Microglia and multiple sclerosis

1. Aarli JA (2003) Role of cytokines in neurological disorders. Curr.Med.Chem. 10:1931-1937
   Abstract: The balance between cytokines with pro- and anti-inflammatory effects contributes to the course of the Guillain-Barre syndrome and chronic inflammatory demyelinating polyneuropathy. TNFalpha seems to be an important factor in the cascade of events leading to demyelination and even axonal damage. During the acute phase, the serum concentrations of TNFalpha and IL-6 are elevated while anti-inflammatory cytokines are up-regulated in the recovery phase. Cytokines also have a key role in the pathogenesis of multiple sclerosis and most data suggest that this effect is mediated by myelin-specific CD4 T lymphocytes secreting Th type 1 cytokines. However, several different immune cells including B lymphocytes, CD8 T lymphocytes and NK T lymphocytes are also involved in the pathogenesis. Both Th1 and Th2 lymphocytes and cytokines probably participate in the development of myasthenia gravis (MG). The IFNalpha production is probably related to the severity of the disease, with clinical improvement associated with decreased production. The serum levels of IL-18 are significantly elevated in MG, with highest concentrations in patients with generalized disease. The immune system may be involved in the pathogenesis of AD by the effect of Microglia, which can induce Microglial activation with subsequent release of pro-inflammatory cytokines. In parkinsonism, there is evidence of chronic inflammation in the substantia nigra and striatum. Activated Microglia, producing proinflammatory cytokines, surround the degenerating dopaminergic neurons and may contribute to the dopaminergic neuron loss. Studies of patients with epilepsy and animals with experimentally induced seizures indicate that cytokines may also influence the electrophysiological properties of neurons

2. Arevalo-Martin A, Vela JM, Molina-Holgado E, Borrell J, Guaza C (2003) Therapeutic action of cannabinoids in a murine model of multiple sclerosis. J.Neurosci. 23:2511-2516
   Abstract: Theiler's virus infection of the CNS induces an immune-mediated demyelinating disease in susceptible mouse strains and serves as a relevant infection model for human multiple sclerosis (MS). Cannabinoids may act as immunosuppressive compounds that have shown therapeutic potential in chronic inflammatory disorders. Using the Theiler's murine encephalomyelitis virus model, we report here that treatment with the synthetic cannabinoids WIN 55,212-2, ACEA, and JWH-015 during established disease significantly improved the neurological deficits in a long-lasting way. At a histological level, cannabinoids reduced Microglial activation, abrogated major histocompatibility complex class II antigen expression, and decreased the number of CD4+ infiltrating T cells in the spinal cord. Both recovery of motor function and diminution of inflammation paralleled extensive remyelination. Overall, the data presented may have potential therapeutic implications in demyelinating pathologies such as MS; in particular, the possible involvement of cannabinoid receptor CB2 would enable nonpsychoactive therapy suitable for long-term use

3. Chan A, Papadimitriou C, Graf W, Toyka KV, Gold R (2003) Effects of polyclonal immunoglobulins and other immunomodulatory agents on Microglial phagocytosis of apoptotic inflammatory T-cells. J.Neuroimmunol. 135:161-165
   Abstract: T-cell apoptosis in the CNS is an effective mechanism for the noninflammatory resolution of autoimmune T-cell infiltrates. Ingestion of apoptotic leukocytes by Microglia results in an efficient clearance of the inflammatory infiltrate, followed by a profound downregulation of proinflammatory phagocyte immune functions. The effects of different immunomodulatory agents on Lewis rat Microglial phagocytosis of apoptotic autologous thymocytes or myelin-basic protein (MBP)-specific, encephalitogenic T-cells were investigated using a standardized, light microscopical in vitro phagocytosis assay. Pretreatment of Microglia with polyclonal 7S immunoglobulins (IVIg) decreased the phagocytosis of apoptotic thymocytes by 38.2% (p<0.0001). Also, immunoglobulin F(ab')(2) fragments decreased Microglial phagocytosis, suggesting an Fc receptor-independent mechanism. Similar results were obtained using MBP-specific T-cells. Pretreatment of Microglia with IFN-gamma increased the phagocytosis of apoptotic cells by 65.4%, which was to a large extent counteracted by IVIg. Glatiramer acetate (GLAT) did not exert an effect on Microglial phagocytosis, while methylprednisolone (MP) induced Microglial apoptosis in vitro. These results indicate that IVIg has a high potential to inhibit Microglial phagocytosis of apoptotic inflammatory T-cells even under proinflammatory conditions and extend our view of the complex immunomodulatory effects of IVIg

4. Cipriani B, Chen L, Hiromatsu K, Knowles H, Raine CS, Battistini L, Porcelli SA, Brosnan CF (2003) Upregulation of group 1 CD1 antigen presenting molecules in guinea pigs with experimental autoimmune encephalomyelitis: an immunohistochemical study. Brain Pathol. 13:1-9
   Abstract: In humans, group 1 CD1 glycoproteins present foreign and self lipid and glycolipid antigens to T-cells. Homologues of these molecules are not found in mice or rats but are present in guinea pigs (GPs). We examined CD1 and MHC class II expression in the central nervous system (CNS) of GPs sensitized for experimental autoimmune encephalomyelitis (EAE), an animal model of multiple sclerosis. In normal GPs and the uninflamed CNS, low-level MHC class II (MHC II) immunoreactivity occurred on vascular elements, meningeal macrophages and parenchymal Microglial cells, whereas immunoreactivity for CD1 was absent. In the inflamed CNS, the majority of infiltrating cells were MHC II+ and Microglia showed increased expression. CD1 immunoreactivity was detected on astrocytes and subsets of inflammatory cells Including B cells and macrophages. Minimal CD1 and MHC II co-expression was noted on inflammatory cells or glia. We conclude that group 1 CD1 molecules are strongly upregulated in the inflamed CNS on subsets of cells distinct from the majority of MHC II bearing cells. The expression of CD1 proteins in such lesions broadens the potential repertoire of antigens recognized at these sites and highlights the value of the GP as a model for studies of the relevance of CD1 molecules in host defense and autoimmune diseases

5. Columba-Cabezas S, Serafini B, Ambrosini E, Aloisi F (2003) Lymphoid chemokines CCL19 and CCL21 are expressed in the central nervous system during experimental autoimmune encephalomyelitis: implications for the maintenance of chronic neuroinflammation. Brain Pathol. 13:38-51
   Abstract: The simultaneous presence of dendritic, T- and B-cells in the central nervous system (CNS) of mice with experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis, suggests that interactions among these cell types might be instrumental in the local induction and maintenance of autoimmune reactions. In this study, we explored the possibility that such aberrant leukocyte recruitment in the CNS could be sustained by "lymphoid" chemokines which orchestrate dendritic cell and lymphocyte homing to lymphoid organs. Transcripts for CCL19 and CCL21 and their common receptor CCR7 were induced in the CNS of mice undergoing relapsing-remitting and chronic-relapsing EAE. While CCL21 immunoreactivity was confined to the endothelium of some inflamed blood vessels, CCL19 was expressed by many infiltrating leukocytes and some astrocytes and Microglia in the CNS parenchyma. CCR7+ cells accumulated in inflammatory lesions during EAE progression, when abundant infiltration of the CNS by mature dendritic cells, B-cells and cells expressing naive T-cell markers also occurred. These findings suggest that CCL19 and CCL21 produced in the EAE-affected CNS may be critical for the homing of antigen presenting cells and lymphocytes, resulting in continuous local antigenic stimulation and maintenance of chronic neuroinflammation

6. Dasgupta S, Jana M, Liu X, Pahan K (2003) Role of very-late antigen-4 (VLA-4) in myelin basic protein-primed T cell contact-induced expression of proinflammatory cytokines in Microglial cells. J.Biol.Chem. 278:22424-22431
   Abstract: The presence of neuroantigen-primed T cells recognizing self-myelin antigens within the CNS is necessary for the development of demyelinating autoimmune disease like multiple sclerosis. This study was undertaken to investigate the role of myelin basic protein (MBP)-primed T cells in the expression of proinflammatory cytokines in Microglial cells. MBP-primed T cells alone induced specifically the Microglial expression of interleukin (IL)-1beta, IL-1alpha tumor necrosis factor alpha, and IL-6, proinflammatory cytokines that are primarily involved in the pathogenesis of MS. This induction was primarily dependent on the contact between MBP-primed T cells and Microglia. The activation of Microglial NF-kappaB and CCAAT/enhancer-binding protein beta (C/EBPbeta) by MBP-primed T cell contact and inhibition of contact-mediated Microglial expression of proinflammatory cytokines by dominant-negative mutants of p65 and C/EBPbeta suggest that MBP-primed T cells induce Microglial expression of cytokines through the activation of NF-kappaB and C/EBPbeta. In addition, we show that MBP-primed T cells express very late antigen-4 (VLA-4), and functional blocking antibodies to alpha4 chain of VLA-4 (CD49d) inhibited the ability of MBP-primed T cells to induce Microglial proinflammatory cytokines. Interestingly, the blocking of VLA-4 impaired the ability of MBP-primed T cells to induce Microglial activation of only C/EBPbeta but not that of NF-kappaB. This study illustrates a novel role of VLA-4 in regulating neuroantigen-primed T cell-induced activation of Microglia through C/EBPbeta

7. Dasgupta S, Zhou Y, Jana M, Banik NL, Pahan K (2003) Sodium phenylacetate inhibits adoptive transfer of experimental allergic encephalomyelitis in SJL/J mice at multiple steps. J.Immunol. 170:3874-3882
   Abstract: Experimental allergic encephalomyelitis (EAE) is the animal model for multiple sclerosis. The present study underlines the importance of sodium phenylacetate (NaPA), a drug approved for urea cycle disorders, in inhibiting the disease process of adoptively transferred EAE in female SJL/J mice at multiple steps. Myelin basic protein (MBP)-primed T cells alone induced the expression of NO synthase (iNOS) and the activation of NF-kappaB in mouse Microglial cells through cell-cell contact. However, pretreatment of MBP-primed T cells with NaPA markedly inhibited its ability to induce Microglial expression of iNOS and activation of NF-kappaB. Consistently, adoptive transfer of MBP-primed T cells, but not that of NaPA-pretreated MBP-primed T cells, induced the clinical symptoms of EAE in female SJL/J mice. Furthermore, MBP-primed T cells isolated from NaPA-treated donor mice were also less efficient than MBP-primed T cells isolated from normal donor mice in inducing iNOS in Microglial cells and transferring EAE to recipient mice. Interestingly, clinical symptoms of EAE were much less in mice receiving NaPA through drinking water than those without NaPA. Similar to NaPA, sodium phenylbutyrate, a chemically synthesized precursor of NaPA, also inhibited the disease process of EAE. Histological and immunocytochemical analysis showed that NaPA inhibited EAE-induced spinal cord mononuclear cell invasion and normalized iNOS, nitrotyrosine, and p65 (the RelA subunit of NF-kappaB) expression within the spinal cord. Taken together, our results raise the possibility that NaPA or sodium phenylbutyrate taken through drinking water or milk may reduce the observed neuroinflammation and disease process in multiple sclerosis patients

8. De Keyser J, Zeinstra E, Frohman E (2003) Are astrocytes central players in the pathophysiology of multiple sclerosis? Arch.Neurol. 60:132-136
   Abstract: An interaction between antimyelin T cells and antigen-presenting glial cells is a crucial step in the cascade of immune events that lead to the inflammatory lesions in multiple sclerosis (MS). One of the most debated and controversial issues is whether Microglial cells or astrocytes are the key players in initiating the (auto)immune reactions in the central nervous system in MS. Many investigators consider Microglia to be the responsible intrinsic immunoeffector cells. In this review, we speculate that in MS astrocytes may serve as primary (facultative) antigen-presenting cells due to a failure of noradrenergic suppression of class II major histocompatibility complex molecules, which is caused by a loss of beta(2)-adrenergic receptors. If this hypothesis is correct, pharmacologic suppression of the antigen-presenting capacities of astrocytes may be a potential therapy for MS

9. Debruyne JC, Versijpt J, Van Laere KJ, De Vos F, Keppens J, Strijckmans K, Achten E, Slegers G, Dierckx RA, Korf J, De Reuck JL (2003) PET visualization of Microglia in multiple sclerosis patients using [11C]PK11195. Eur.J.Neurol. 10:257-264
   Abstract: Activated Microglia are involved in the immune response of multiple sclerosis (MS). The peripheral benzodiazepine receptor (PBR) is expressed on Microglia and up-regulated after neuronal injury. [11C]PK11195 is a positron emission tomography (PET) radioligand for the PBR. The objective of the present study was to investigate [11C]PK11195 imaging in MS patients and its additional value over magnetic resonance imaging (MRI) concerning the immuno-pathophysiological process. Seven healthy and 22 MS subjects were included. Semiquantitative [11C]PK11195 uptake values were assessed with normalization on cortical grey matter. Uptake in Gadolinium-lesions was significantly increased compared with normal white matter. Uptake in T2-lesions was generally decreased, suggesting a PBR down-regulation. However, uptake values increased whenever a clinical or MR-relapse was present, suggestive for a dynamic process with a transient PBR up-regulation. During disease progression, an increase of normal-appearing white matter (NAWM) uptake was found, propagating NAWM as the possible real burden of disease. In conclusion, [11C]PK11195 and PET are able to demonstrate inflammatory processes with Microglial involvement in MS

10. Delgado M, Ganea D (2003) Vasoactive intestinal peptide prevents activated Microglia-induced neurodegeneration under inflammatory conditions: potential therapeutic role in brain trauma. FASEB J. 17:1922-1924
    Abstract: In most neurodegenerative disorders, including multiple sclerosis, Parkinson's disease, and Alzheimer's disease, a massive neuronal cell death occurs as a consequence of an uncontrolled inflammatory response, where activated Microglia and its cytotoxic agents play a crucial pathologic role. Because current treatments for these diseases are not effective, several regulatory molecules termed "Microglia-deactivating factors" recently have been the focus of considerable research. Vasoactive intestinal peptide (VIP) is a neuropeptide with a potent anti-inflammatory effect, which has been found to protect from other inflammatory disorders, such as endotoxic shock and rheumatoid arthritis. In the present study, we investigate the effect of VIP on inflammation-mediated neurodegeneration in vitro and in vivo as well as on the putative neuroprotective effect of VIP on experimental pathological conditions in which central nervous system (CNS) inflammation is involved, such as brain trauma. The involvement of activated Microglia and their derived cytotoxic products is also studied. VIP has a clear neuroprotective effect on inflammatory conditions by inhibiting the production of Microglia-derived proinflammatory factors (tumor necrosis factor alpha, interleukin-1beta, nitric oxide). In this sense, VIP prevents neuronal cell death following brain trauma by reducing the inflammatory response of neighboring Microglia. Therefore, VIP emerges as a valuable neuroprotective agent for the treatment of pathologic conditions of the CNS where inflammation-induced neurodegeneration occurs

11. Dimayuga FO, Ding Q, Keller JN, Marchionni MA, Seroogy KB, Bruce-Keller AJ (2003) The neuregulin GGF2 attenuates free radical release from activated Microglial cells. J.Neuroimmunol. 136:67-74
    Abstract: The neuregulin glial growth factor 2 (GGF2) is a neural growth factor that is best known for its ability to promote the survival and proliferation of oligodendrocytes and Schwann cells. While it has been shown in recent years that GGF2 is effective in the treatment of autoimmune models of brain injury, it is not known if the beneficial effects of GGF2 are based in part on modulation of brain inflammation. In this report, we document the anti-inflammatory effects of recombinant human GGF2 (rhGGF2) on Microglial free radical production in vitro. The presence of the neuregulin receptors ErbB2, 3, and 4 was confirmed in N9 Microglial cells by Western blot analysis. Pretreatment of N9 cells with 10-100 ng/ml rhGGF2 24 h before either phorbol 12-myristate 3-acetate (PMA) or interferon gamma (IFNgamma) caused dose-dependent decreases in oxidative burst activity and nitrite release, respectively, with 50 and 100 ng/ml causing significant effects. When cells were co-treated with increasing doses of rhGGF2 and PMA or IFNgamma, only concentrations of 50 ng/ml, but not 10 or 100 ng/ml, were able to decrease oxidative burst activity and nitrite release. Finally, when Microglial cell viability following treatment of cells with IFNgamma with or without rhGGF2 was evaluated, it was observed that 50 and 100 ng/ml rhGGF2 conferred significant protection against IFNgamma-induced cell death in Microglial cells. Overall, these results indicate that the neuregulin rhGGF2 may have anti-inflammatory and antioxidant properties in the brain, and may also provide trophic support for brain-resident Microglial cells

12. Filipovic R, Jakovcevski I, Zecevic N (2003) GRO-alpha and CXCR2 in the human fetal brain and multiple sclerosis lesions. Dev.Neurosci. 25:279-290
    Abstract: Chemokines, small proinflammatory cytokines, are involved in migration of inflammatory cells, but also have a role in normal central nervous system development. One chemokine, growth-related oncogene-alpha (GRO-alpha) and its receptor CXCR2, are involved in proliferation and migration of oligodendrocyte progenitors in rats. Here we studied the regional and cell type-specific expression of GRO-alpha and CXCR2 in the human telencephalon at midgestation, the time that oligodendrocytes are being generated in the human brain. Our results showed that both GRO-alpha and CXCR2 are predominately expressed by oligodendrocyte progenitors and activated Microglial cells in the highly proliferative subventricular zone. This cellular and regional localization suggests that GRO-alpha/CXCR2 may play a role in human oligodendrocyte proliferation and subsequent migration. We also studied the expression of GRO-alpha and CXCR2 in brain sections of multiple sclerosis (MS) patients. Consistent with their role in the inflammatory process of MS, both GRO-alpha and CXCR2 were expressed in activated Microglia localized on the border of MS lesions. However, neither GRO-alpha nor CXCR2 were present in early oligodendrocyte progenitors, a finding that may partially explain why remyelination is not more efficient in MS

13. Fukaura H, Kikuchi S (2003) [IL-18 in multiple sclerosis]. Nippon Rinsho 61:1416-1421
    Abstract: IL-18, previously named interferon-gamma inducing factor, is produced by monocytes/macropharges, dendritic cells, B cells and other APC cells as well as by astrocytes, Microglia. IL-18 is a unique cytokine that stimulates both Th1 and Th2 responses depending on its cytokine milieu. Caspase-1 regulates the cellular export of IL-18. Anti IL-18 antibodies prevent EAE. IL-18 directs autoreactive T cells and promotes autodestruction in CNS via induction of IFN-gamma by NK cells in EAE. IL-18 is expressed in MS plaque. Common IL-18 promoter polymorphisms influence the expression on IL-18. IL-18 is linked to raised IFN-gamma in MS and is induced by activated CD4(+) T cells via CD40-CD40 ligand interaction. IL-18 in MS is suppressed by treatments such as GA and IFN-beta

14. Garcion E, Sindji L, Nataf S, Brachet P, Darcy F, Montero-Menei CN (2003) Treatment of experimental autoimmune encephalomyelitis in rat by 1,25-dihydroxyvitamin D3 leads to early effects within the central nervous system. Acta Neuropathol.(Berl) 105:438-448
    Abstract: We report here that curative treatment of the multiple sclerosis paradigm, chronic relapsing experimental autoimmune encephalomyelitis (EAE) of the Lewis rat, by 1,25-dihydroxyvitamin D(3 )(1,25-D3) leads to a rapid clinical improvement accompanied by an inhibition of CD4, MHC class II and type II nitric oxide synthase (NOS II) expression in the posterior areas of the central nervous system (CNS). In contrast, the hormone has no effect on transforming growth factor-beta1 transcripts. Computer analysis of the NOS II promoter, expressed by Microglia and astrocytes, reveals consensus sequence for vitamin D receptor binding, emphasizing the idea that 1,25-D3 may regulate some aspects of EAE by acting directly on CNS constituent cells. We also demonstrate that vitamin D deprivation leads to minimal effects on the kinetic profile of EAE accompanied by a moderate exacerbation of the clinical symptoms. Interestingly, curative treatment of vitamin D-deprived rats with a non-toxic-1,25-D3 analogue (MC1288) strongly inhibited EAE symptoms, thus promulgating the potential interest of such compounds in the management of multiple sclerosis

15. Geurts JJ, Wolswijk G, Bo L, van d, V, Polman CH, Troost D, Aronica E (2003) Altered expression patterns of group I and II metabotropic glutamate receptors in multiple sclerosis. Brain 126:1755-1766
    Abstract: Recent evidence supports a role for glutamate receptors in the pathophysiology of multiple sclerosis. In the present study, we have focused specifically on the expression of metabotropic glutamate receptors (mGluRs) in multiple sclerosis brain tissue. The expression of group I (mGluR1alpha and mGluR5) and group II (mGluR2/3) mGluRs was studied using immunohistochemistry in tissue from 12 multiple sclerosis cases and seven non-neurological controls. The expression patterns of both group I and II mGluRs in multiple sclerosis tissue differed significantly from those in control tissue. Strong mGluR1alpha immunoreactivity was observed in axons of the subcortical white matter, particularly in the centre of actively demyelinating lesions and in the borders of chronic active lesions. mGluR1alpha axonal immunopositivity was also found in normal appearing multiple sclerosis white matter, but axons in control white matter were generally negative. mGluR1alpha axonal labelling was associated with the presence of non-phosphorylated neurofilaments and beta-amyloid precursor protein, which are sensitive markers for axonal injury and disturbed axonal transport. Changes in mGluR immunoreactivity were also observed in glia. A diffuse increase in the expression of mGluR5 and mGluR2/3 was detected in reactive astrocytes in multiple sclerosis lesions. However, only a subpopulation of reactive astroglial cells expressed mGluR1alpha. In addition, labelling with antibodies to mGluR2/3 and, to a lesser extent labelling with antibodies to mGluR1alpha, was detected in a population of cells of the Microglial/macrophage lineage that displayed a macrophage-like morphology. Our data suggest that mGluRs, like ionotropic glutamate receptors, play a role in the complex processes that are associated with the progressive brain damage in multiple sclerosis, including both glial activation and pathological changes in axons

16. Goodman AD, Mock DJ, Powers JM, Baker JV, Blumberg BM (2003) Human herpesvirus 6 genome and antigen in acute multiple sclerosis lesions. J.Infect.Dis. 187:1365-1376
    Abstract: Evidence for a candidate multiple sclerosis (MS) virus, human herpesvirus 6 (HHV-6), was sought in biopsy specimens of acute lesions that presented clinically as cerebral tumors obtained from 5 patients. Histopathology, magnetic resonance imaging, and clinical course confirmed the diagnosis of MS in each case. A sensitive in situ polymerase chain reaction (ISPCR) method was used to detect HHV-6 genome, in conjunction with immunocytochemical staining (ICC) to detect viral and cellular antigens. ISPCR revealed numerous oligodendrocytes, lymphocytes, and Microglia containing HHV-6 genome within all lesions, whereas ICC showed only the HHV-6 glycoprotein 116 antigen in some reactive astrocytes and Microglia. High frequencies of neuroglial and inflammatory cells containing HHV-6 genome were present in acute-phase lesion tissue from patients who were free of the effects of chronic MS and had not been received immunomodulatory therapy for MS. The prevalence of HHV-6 genome-containing cells, including oligodendrocytes, in each lesion suggests that HHV-6 plays a role in the demyelinative pathogenesis of MS; the significance of the discrepant expression of viral antigens remains uncertain

17. Hisahara S, Okano H, Miura M (2003) Caspase-mediated oligodendrocyte cell death in the pathogenesis of autoimmune demyelination. Neurosci.Res. 46:387-397
    Abstract: multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), are inflammatory diseases of the central nervous system (CNS) characterized by localized areas of demyelination. MS is believed to be an autoimmune disorder mediated by activated immune cells such as T- and B-lymphocytes and macrophages/Microglia. Lymphocytes are primed in the peripheral tissues by antigens, and clonally expanded cells infiltrate the CNS. They produce large amounts of inflammatory and cytokines that lead to demyelination and axonal degeneration. Although several studies have shown that oligodendrocytes (OLGs), the myelin-forming glial cells in the CNS, are sensitive to cell death stimuli, such as cytotoxic cytokines, anti-myelin antibodies, nitric oxide, and oxidative stress, in vitro, the mechanisms underlying injury to the OLGs in MS/EAE remain unclear. Transgenic mice that express the anti-apoptotic protein specifically in OLGs and caspase-11-deficient mice are significantly resistant to EAE induction. Histopathological analyses show that the number of caspase-activated OLGs and dead OLGs are reduced in the CNS of these mice. The numbers of infiltrating immune cells and the amounts of cytokines are also markedly reduced in EAE lesions. Therefore, caspase-mediated OLG death leads to the exacerbation of demyelination and the deterioration of neurological manifestations by inducing local inflammatory events

18. Hosokawa M, Klegeris A, Maguire J, McGeer PL (2003) Expression of complement messenger RNAs and proteins by human oligodendroglial cells. Glia 42:417-423
    Abstract: Neurons, astrocytes, Microglia, and endothelial cells are capable of synthesizing most, if not all, of the complement proteins. Little is known, however, about the capacity of oligodendroglial cells to generate complement components. This study evaluated expression of complement mRNAs and their protein products by human oligodendrocytes. Cells were isolated and cultured from white matter of seven adult cases that had undergone surgical temporal lobe resection for epilepsy. Oligodendroglial cultures were characterized by the expression of such cell type-specific mRNAs as myelin proteolipid protein (PLP), oligodendrocyte-specific protein (OSP), and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and were further characterized by immunostaining for such differentiation markers as myelin basic protein (MBP), PLP, CNPase, and O4. RT-PCR analysis showed that the oligodendroglial cells expressed detectable levels of complement mRNAs for the C1q B-chain, C1r, C1s, C2, C3, C4, C5, C6, C7, C8 gamma subunit, and C9. Immunostaining was positive for C1q, C1s, C2, C3, C4, C5, C6, C7, C8, and C9. Double immunostaining for the oligodendrocyte marker O4 and the complement protein C3 demonstrated that all O4-positive cells were also positive for C3, indicating constitutive C3 expression. These results indicate that oligodendroglial cells may be a source of complement proteins in human brain and thus could contribute to the pathogenesis of several neurodegenerative and inflammatory diseases of the CNS, such as Alzheimer's disease, multiple sclerosis, and progressive supranuclear palsy, where complement-activated oligodendrocytes are abundant

19. Hulshof S, van Haastert ES, Kuipers HF, van den Elsen PJ, De Groot CJ, van d, V, Ravid R, Biber K (2003) CX3CL1 and CX3CR1 expression in human brain tissue: noninflammatory control versus multiple sclerosis. J.Neuropathol.Exp.Neurol. 62:899-907
    Abstract: An important role for CX3CL1 in neuroinflammation and neurodegeneration has been suggested in recent publications. In this study, we compared the expression of CX3CL1 and its receptor CX3CR1 in human brain tissue derived from control patients without neurological complications and in multiple sclerosis (MS) patients. Results from this study demonstrate that CX3CL1 is constitutively expressed in human central nervous system (CNS) astrocytes in vivo and under basal conditions in human adult astrocyte cultures. CX3CR1 is expressed on astrocytes and Microglial cells both in vivo and in vitro. Chemotaxis assay shows a functional response upon CX3CR1 signaling in Microglial cells. Although CX3CL1 expression is upregulated in cultured astrocytes in response to proinflammatory cytokines, no evidence for expression differences of CX3CL1 between control patients and MS patients was found. Our data suggest that CX3CL1 has more general physiological functions, which occur also in the absence of proinflammatory conditions

20. Kato H, Suzumura A (2003) [Cytokines in MS lesion]. Nippon Rinsho 61:1428-1434
    Abstract: A variety of cytokines are involved in the pathogenesis of multiple sclerosis(MS), either in induction phase and effector phase. In order to interact with immune cells, the cells in the brain have to express MHC antigens which they do not usually express. Cytokines such as IFN gamma, IL-3 and TNF alpha induce MHC antigen expression on neural cells. IFN gamma also induces costimulatory molecule for antigen presentation and also induce IL-12, a critical cytokine in T helper cell differentiation, in Microglia. Although TNF alpha is a critical cytokines in effector phase, other cytokines and chemokines have also been shown to play roles on the development of inflammatory demyelination and gliosis. In this chapter, we will review the cytokine profile of MS lesions

21. Kielian T, Drew PD (2003) Effects of peroxisome proliferator-activated receptor-gamma agonists on central nervous system inflammation. J.Neurosci.Res. 71:315-325
    Abstract: Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) plays a critical role in glucose and lipid metabolism. More recently, PPAR-gamma ligands have been reported to inhibit the expression of proinflammatory molecules by monocytes/macrophages. Of relevance to CNS disease is that PPAR-gamma agonists have been demonstrated to have similar effects on Microglia. PPAR-gamma agonists also ameliorate experimental autoimmune encephalomyelitis, an animal model of multiple sclerosis. This Mini-Review summarizes the effects of PPAR-gamma agonists in mediating immune responses and the potential of these agonists in the treatment of inflammatory disorders of the CNS

22. Kleine TO, Zwerenz P, Graser C, Zofel P (2003) Approach to discriminate subgroups in multiple sclerosis with cerebrospinal fluid (CSF) basic inflammation indices and TNF-alpha, IL-1beta, IL-6, IL-8. Brain Res.Bull. 61:327-346
    Abstract: Lumbar CSF and serum pairs of untreated multiple sclerosis patients (MS; n=47) were analyzed on admission. On average, higher CSF leukocyte (lymphocyte and monocyte) counts, IgG index, CSF IgG contents, but not of TNF-alpha, IL-1beta, IL-6, IL-8 in CSF and serum, were revealed in all MS or patients with long disease course (LO-MS) compared with controls. In primary progressive MS (PP-MS) cell counts were low, but IgG contents were high, when compared to relapsing-remitting MS (RR-MS). In clinically probable MS (CP-MS) both contents were low, in clinically definite MS (CD-MS) high. Spearman's correlation with the four monokines and the basic indices in CSF revealed activation patterns known for Microglia/macrophages in the four MS subgroups, for astrocytes in CP-MS and RR-MS, for CSF lymphocytes in CP-MS and PP-MS, for cells of blood-brain barrier (BBB) in CP-MS, for intrathecal IgG synthesis in PP-MS and for lymphocyte transfer in CD-MS. Correlations between CSF and serum parameters indicated CNS disease processes to be associated with systemic processes of inflammation (acute, chronic) in CD-MS, RR-MS, and PP-MS in different ways. CSF IgG content, IgG index and systemic markers of inflammation correlated with overall disability scores in LO-MS; increasing levels may indicate a bad outcome

23. Kwidzinski E, Mutlu LK, Kovac AD, Bunse J, Goldmann J, Mahlo J, Aktas O, Zipp F, Kamradt T, Nitsch R, Bechmann I (2003) Self-tolerance in the immune privileged CNS: lessons from the entorhinal cortex lesion model. J.Neural Transm.Suppl29-49
    Abstract: Upon peripheral immunization with myelin epitopes, susceptible rats and mice develop T cell-mediated demyelination similar to that observed in the human autoimmune disease multiple sclerosis (MS). In the same animals, brain injury does not induce autoimmune encephalomyelitis despite massive release of myelin antigens and early expansion of myelin specific T cells in local lymph nodes, indicating that the self-specific T cell clones are kept under control. Using entorhinal cortex lesion (ECL) to induce axonal degeneration in the hippocampus, we identified possible mechanisms of immune tolerance after brain trauma. Following ECL, astrocytes upregulate the death ligand CD95L, allowing apoptotic elimination of infiltrating activated T cells. Myelin-phagocytosing Microglia express MHC-II and the costimulatory molecule CD86, but lack CD80, which is found only on activated antigen presenting cells (APCs). Restimulation of invading T cells by such immature APCs (e.g. CD80 negative Microglia) may lead to T cell anergy and/or differentiation of regulatory/Th3-like cells due to insufficient costimulation and presence of high levels of TGF-beta and IL-10 in the CNS. Thus, T cell -apoptosis, -anergy, and -suppression apparently maintain immune tolerance after initial expansion of myelin-specific T lymphocytes following brain injury. This view is supported by a previous metastatistical analysis which rejected the hypothesis that brain trauma is causative of MS (Goddin et al., 1999). However, concomitant trauma-independent proinflammatory signals, e.g., those evoked by clinically quiescent infections, may trigger maturation of APCs, thus shifting a delicate balance from immune tolerance and protective immune responses to destructive autoimmunity

24. Lampe JB, Schneider-Schaulies S, Aguzzi A (2003) Expression of the interferon-induced MxA protein in viral encephalitis. Neuropathol.Appl.Neurobiol. 29:273-279
    Abstract: MxA protein accumulates cytoplasmically in response to interferon stimulation, and mediates resistance against several viruses. In order to test whether MxA may serve as a diagnostic tool for viral infections of the central nervous system (CNS), we performed MxA immunohistochemistry on biopsies and autopsies of 57 patients with neurological disorders of known viral and nonviral aetiology. MxA was detectable in all HIV patients with proven opportunistic viral encephalitis, in all patients suffering from isolated viral encephalitis, in one of three HIV patients with cerebral toxoplasmosis, and in one case of micronodular encephalitis. No MxA was detectable in HIV patients with isolated HIV encephalitis or HIV infection accompanied by an opportunistic nonviral disorder. We were unable to show MxA expression in a variety of nonviral inflammatory and noninflammatory disorders of the CNS. Several cases of Rasmussen's encephalitis and multiple sclerosis tested negative, arguing against their possible viral aetiology. Two-colour immunohistochemistry identified macrophages and activated Microglia as MxA expressing cells. In all studied cases MxA expression was accompanied by a marked T-cell infiltrate. Therefore, the detection of MxA-protein is a sensitive adjuvant marker for those cases of viral encephalitis which are accompanied by pronounced lymphocytic infiltrates

25. Lassmann H (2003) Hypoxia-like tissue injury as a component of multiple sclerosis lesions. J.Neurol.Sci. 206:187-191
    Abstract: Recent data suggest that the mechanisms of demyelination and tissue damage in multiple sclerosis (MS) are heterogenous. In this review, evidence is discussed, which show that in a subset of multiple sclerosis patients the central nervous system (CNS) lesions show profound similarities to tissue alterations found in acute white matter stroke, thus suggesting that a hypoxia-like metabolic injury is a pathogenetic component in a subset of inflammatory brain lesions. Both, vascular pathology as well as metabolic disturbances induced by toxins of activated macrophages and Microglia may be responsible for such lesions in multiple sclerosis

26. Lieb K, Engels S, Fiebich BL (2003) Inhibition of LPS-induced iNOS and NO synthesis in primary rat Microglial cells. Neurochem.Int. 42:131-137
    Abstract: Nitric oxide (NO) has been implicated in the etiopathology of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), and inhibition of NO synthesis has been proposed to be a possible mechanism of action of drugs to treat MS. In the present study, we investigated the inhibitory effect on NO synthesis of various steroids, cytokines and drugs used or proposed for the treatment of MS. As a model system, we used primary rat Microglial cells which produce NO synthase and subsequently release NO upon stimulation with lipopolysaccharide (LPS). Among the substances tested, the glucocorticoids prednisone, hydrocortisone, dexamethasone and progesterone as well as transforming growth factor-beta (TGF-beta) dose-dependently inhibited LPS-induced nitric oxide synthase (iNOS) and NO synthesis. In contrast, COP-1, the phosphodiesterase inhibitors rolipram and pentoxifylline, the cytokines interleukin-10 (IL-10) and interferon-beta (IFN-beta) as well as the steroids beta-estradiol, testosterone, and dehydroepiandrosterone (DHEA) showed no inhibitory effect. Cholesterol slightly, but not significantly, increased LPS-induced nitric oxide synthesis. We conclude from the present study that with respect to treatment of MS, inhibition of NO synthesis may be an important mechanism of action of glucocorticoids and transforming growth factor-beta, but not of other drugs used or proposed to treat MS

27. Luttichau HR, Clark-Lewis I, Jensen PO, Moser C, Gerstoft J, Schwartz TW (2003) A highly selective CCR2 chemokine agonist encoded by human herpesvirus 6. J.Biol.Chem. 278:10928-10933
    Abstract: The chemokine-like, secreted protein product of the U83 gene from human herpesvirus 6, here named vCCL4, was chemically synthesized to be characterized in a complete library of the 18 known human chemokine receptors expressed individually in stably transfected cell lines. vCCL4 was found to cause calcium mobilization as efficiently as the endogenous chemokine ligand CCL2 through the CCR2 receptor, whereas the virally encoded chemokine did not affect any of the other 17 human chemokine receptors tested. Mutual cross-desensitization between CCL2 and vCCL4 was demonstrated in the CCR2-transfected cells. The affinity of vCCL4 for the CCR2 receptor was 79 nm as determined in competition binding against radioactively labeled CCL2. In the murine pre-B lymphocyte cell line L1.2 stably transfected with the CCR2 receptor, vCCL4 acted as a relatively low potency but highly efficacious chemoattractant being equally or more efficacious in causing cell migration than CCL2 and CCL7 and considerably more efficacious than CCL8 and CCL13. It is concluded that human herpesvirus 6 encodes a highly selective and efficacious CCR2 agonist, which will attract CCR2 expressing cells, for example macrophages and monocytes, conceivably for the virus to infect and to establish latency in. It is suggested that vCCL4 during reactivation of the virus in for example monocyte-derived Microglia could perhaps be involved in the pathogenesis of the CCR2-dependent disease, multiple sclerosis

28. Milicevic I, Pekovic S, Subasic S, Mostarica-Stojkovic M, Stosic-Grujicic S, Medic-Mijacevic L, Pejanovic V, Rakic L, Stojiljkovic M (2003) Ribavirin reduces clinical signs and pathological changes of experimental autoimmune encephalomyelitis in Dark Agouti rats. J.Neurosci.Res. 72:268-278
    Abstract: The effect of ribavirin on development of experimental autoimmune encephalomyelitis (EAE) was investigated. The disease was induced in genetically susceptible Dark Agouti rats with syngeneic spinal cord homogenate in complete Freund's adjuvant (SCH-CFA). Depending on the amount of mycobacteria in CFA, the animals developed either moderate or severe EAE. Ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide) was applied i.p. at a daily dosage of 30 mg/kg in two treatment protocols: from the start of immunization (preventive treatment) or from the onset of the first EAE signs after the induction (therapeutic treatment). Signs of EAE began between 7 and 9 days after induction and peaked at days 11-13. In moderate EAE (mean maximal severity score 3.33 +/- 0.21), the recovery was completed by days 23-26, whereas, in severe EAE (mean maximal severity score 4.5 +/- 0.23), obvious recovery was not detected. Preventive ribavirin treatment significantly decreased clinical signs after both moderate (score 1.75 +/- 0.25, P < 0.05) and severe (score 3.62 +/- 0.31, P < 0.015) immunization. Also, disease manifestations were reduced by therapeutic treatment of ribavirin (mean maximal severity score 2.5 +/- 0.2 vs. 3.33 +/- 0.21 in controls, P < 0.005) but less so in comparison with preventive treatment. Analysis of the effects of ribavirin on histopathologic changes in the spinal cord tissue revealed a reduction of mononuclear cell infiltrates, composed of T cells and macrophages/Microglia, and the absence of demyelination, which were pronounced in control EAE animals. Beneficial effects of preventive and therapeutic treatment with ribavirin on development of EAE suggest this nucleoside analogue as a useful candidate for therapy in multiple sclerosis

29. Mizuno T, Kawanokuchi J, Numata K, Suzumura A (2003) Production and neuroprotective functions of fractalkine in the central nervous system. Brain Res. 979:65-70
    Abstract: The CX3C-chemokine, fractalkine is reportedly to be expressed in the central nervous system, and up-regulated in certain pathological conditions, such as HIV encephalopathy and multiple sclerosis. In the present study, we examined the production of fractalkine and the expression of its receptor, CX3CR1 in murine glial and neuronal cell in vitro, and investigated its neuroprotective functions. Both fractalkine and CX3CR1 were expressed constitutively in neurons, Microglia, and astrocytes. Neither the production of fractalkine nor its receptor expression was up-regulated by lipopolysaccharide (LPS), as measured by mRNA expression and protein synthesis. Fractalkine dose-dependently suppressed the production of nitric oxide (NO), interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha with activated Microglia. It also significantly suppressed neuronal cell death induced by Microglia activated with LPS and interferon-gamma, in a dose-dependent manner. These results suggest the possible functions of fractalkine as an intrinsic inhibitor against neurotoxicity by activated Microglia

30. Mokhtarian F, Huan CM, Roman C, Raine CS (2003) Semliki Forest virus-induced demyelination and remyelination--involvement of B cells and anti-myelin antibodies. J.Neuroimmunol. 137:19-31
    Abstract: Semliki Forest virus (SFV) infection induces a demyelinating encephalomyelitis in the central nervous system (CNS) of mice and serves as a model for multiple sclerosis (MS). This study investigated CNS immune responses at different stages of infection and during SFV-induced demyelination and remyelination. Following the initial CNS inflammation, pathology and viral clearance on days 6-10 post-infection (pi), primary demyelination was observed in cerebellar, brainstem and corpus collosal white matter by days 15-21 pi, with plasma cells and Microglia as main participants, and this was followed by remyelination. By day 35 pi, the tissue appeared almost normal. Fluorescent antibody cell sorter (FACS) analysis showed that brain CD8(+) T cells increased during the initial inflammatory response and gradually decreased thereafter. Brain B cell (B220(+)CD19(+)) numbers did not change significantly during the course of infection; however, from days 14 to 35 pi, they matured and produced antibodies to viral and myelin proteins (and peptides) during the period of demyelination and remyelination. The proportion of CD3(-)B220(-)CD11b(+) cells also progressively increased throughout the periods of de- and remyelination. Our results suggest that CD8(+) T cells are involved in the initial destruction of CNS tissue during the first weeks of SFV infection, while B cells, antibodies and Microglia may contribute to the myelin pathology seen after recovery

31. Molina-Monasterios MC, Molina-Abecia H (2003) [Nasu Hakola disease: a report of the first two cases in Bolivia]. Rev.Neurol. 36:837-840
    Abstract: INTRODUCTION: Nasu Hakola disease (NHD) is a progressive dementia that presents accompanied by bone cysts and, at random, epilepsy. It is an autosomal recessive hereditary disease and its genetic defect is located at the 19q13.1 chromosome. The genetic mutation was identified at DAP 12. It appears that DAP 12 is expressed in the Microglial activation and the differentiation of macrophages in the central nervous system and, at the same time, in the osteoclasts in charge of bone remodelling. This double character consisting of dementia and bone cysts, which contain triglycerides and thin PAS positive membranes in a bone with cortical erosion and medullary hypoplasia, enables us to differentiate this disease from other frontotemporal neurodegenerative disorders, such as Pick s disease. At the same time this also allows it to be distinguished from multiple sclerosis, metachromatic leukodystrophy, Marchafava Bignami disease, and prion diseases (such as new variant Creutzfeldt Jakob). CASE REPORTS: In this paper we describe two cases of NHD, also known as polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy, in which progressive dementia, bone cysts and epilepsy were identified. Serious brain atrophy was found and confirmed by imaging studies and brain biopsies, which were also used to rule out other degenerative diseases of the frontal lobe, as well as Creutzfeldt Jakob disease. CONCLUSIONS: Both cases meet all the necessary criteria to satisfy a diagnosis of NHD. This is a hereditary, little known disease whose genetic alterations (i.e. mutations) are still in need of further study. It mainly affects males, who suffer the onset of dementia in their thirties. The neurological disorders constitute a frontal syndrome, due to predominant prefrontal involvement, and they occur in the dorsolateral area, with disorders affecting the executive and planning functions; in the orbitofrontal area, which is reflected in social maladjustment and clear obsessive compulsive traits; and also in the medial or cingulate area, which manifests itself as apathy and lack of motivation. When dealing with this disease, in addition to symptomatic therapy, genetic counselling is also important

32. Nakanishi H (2003) Microglial functions and proteases. Mol.Neurobiol. 27:163-176
    Abstract: There is accumulating evidence that intracellular and extracellular proteases of Microglia contribute to various events in the central nervous system (CNS) through both nonspecific and limited proteolysis. Cathepsin E and cathepsin S, endosomal/lysosomal proteases, have been shown to play important roles in the major histocompatibility complex (MHC) class II-mediated antigen presentation of Microglia by processing of exogenous antigens and degradation of the invariant chain associated with MHC class II molecules, respectively. Some members of cathepsins are also involved in neuronal death after secreted from Microglia and clearance of phagocytosed amyloid- beta peptides. Tissue-type plasminogen activator, a serine protease, secreted from Microglia participates in neuronal death, enhancement of N-methyl-D-aspartate receptor-mediated neuronal responses, and activation of Microglia via either proteolytic or nonproteolytic activity. Calpain, a calcium-dependent cysteine protease, has been shown to play a pivotal role in the pathogenesis of multiple sclerosis by degrading myelin proteins extracellulary. Furthermore, matrix metalloproteases secreted from Microglia also receive great attention as mediators of inflammation and tissue degradation through processing of pro-inflammatory cytokines and damage to the blood-brain barrier. The growing knowledge about proteolytic events mediated by Microglial proteases will not only contribute to better understanding of Microglial functions in the CNS but also may aid in the development of protease inhibitors as novel neuroprotective agents

33. Neumann H (2003) Molecular mechanisms of axonal damage in inflammatory central nervous system diseases. Curr.Opin.Neurol. 16:267-273
    Abstract: PURPOSE OF REVIEW: Axonal dysfunction and damage is an early pathological sign of autoimmune central nervous system disease, viral and bacterial infections, and brain trauma. Axonal injury has attracted considerable interest during the past few years because the degree of axonal damage appears to determine long-term clinical outcome. RECENT FINDINGS: Advanced magnetic resonance spectroscopic imaging techniques have suggested that axonal loss and dysfunction is responsible for the persistent neurological deficits that occur in patients with multiple sclerosis. Histopathological methods have shown that axonal damage is defined primarily by dysfunction of axonal transport, and finally by complete transection and degeneration of axons. Recent studies have demonstrated that the extent of axonal damage in the primary demyelinating lesion of multiple sclerosis patients is associated with the number of activated Microglia/macrophages and cytotoxic CD8+ T lymphocytes. In addition, diffuse axonal dysfunction independent of demyelination develops in normal appearing white matter, possibly due to indirect effects of inflammation. SUMMARY: The fact that axonal damage in response to overt inflammatory reactions may occur gradually, leaving a window for therapeutical intervention, has important clinical implications. Determination of the exact molecular mechanism might help in finding new therapies for inflammatory axonal damage

34. Olson JK, Zamvil SS, Miller SD (2003) Efficient technique for immortalization of murine Microglial cells relevant for studies in murine models of multiple sclerosis. J.Neurosci.Methods 128:33-43
    Abstract: Microglia are macrophage-like cells that populate the central nervous system (CNS) and become activated upon injury or infection. Microglia have been implicated as playing critical roles in various CNS diseases including multiple sclerosis (MS), a human autoimmune demyelinating disease, as well as in other neurodegenerative diseases. Two well-characterized models of MS, relapsing experimental autoimmune encephalomyelitis (R-EAE) and Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease, are inducible in SJL mice and model the relapsing-remitting and chronic-progressive forms of MS, respectively. These models are useful for the study of the mechanisms of initiation, progression, and therapy of the disease. Currently, a major limitation to studying the functions of Microglia in these murine models of MS is the restricted number of cells capable of being isolated from the CNS of neonatal mice and propagated in culture. The current studies describe the preparation of SV-40 large T antigen-immortalized mouse Microglia lines, M4T.4 and M4T.6, from the SJL/J mice. The immortalization technique was very efficient requiring only 6 weeks to develop long-term, highly replicating cell lines. The resulting Microglia cell lines remain quiescent, but are induced to express various immune cytokines and to function as efficient antigen presenting cells upon activation with IFN-gamma or infection with TMEV. Thus, the SV-40 large T antigen immortalized Microglia lines react to innate and infectious stimuli similar to primary Microglia isolated from neonatal mice, but are more easily maintained in culture. This technique should allow for the efficient cultivation of large numbers of Microglial cells from a variety of disease-relevant mouse strains, including knock-out and transgenic mice

35. Palma JP, Kwon D, Clipstone NA, Kim BS (2003) Infection with Theiler's murine encephalomyelitis virus directly induces proinflammatory cytokines in primary astrocytes via NF-kappaB activation: potential role for the initiation of demyelinating disease. J.Virol. 77:6322-6331
    Abstract: Theiler's virus infection in the central nervous system (CNS) induces a demyelinating disease very similar to human multiple sclerosis. We have assessed cytokine gene activation upon Theiler's murine encephalomyelitis virus (TMEV) infection and potential mechanisms in order to delineate the early events in viral infection that lead to immune-mediated demyelinating disease. Infection of SJL/J primary astrocyte cultures induces selective proinflammatory cytokine genes (interleukin-12p40 [IL-12p40], IL-1, IL-6, tumor necrosis factor alpha, and beta interferon [IFN-beta]) important in the innate immune response to infection. We find that TMEV-induced cytokine gene expression is mediated by the NF-kappaB pathway based on the early nuclear NF-kappaB translocation and suppression of cytokine activation in the presence of specific inhibitors of the NF-kappaB pathway. Further studies show this to be partly independent of dsRNA-dependent protein kinase (PKR) and IFN-alpha/beta pathways. Altogether, these results demonstrate that infection of astrocytes and other CNS-resident cells by TMEV provides the early NF-kappaB-mediated signals that directly activate various proinflammatory cytokine genes involved in the initiation and amplification of inflammatory responses in the CNS known to be critical for the development of immune-mediated demyelination

36. Perry VH, Newman TA, Cunningham C (2003) The impact of systemic infection on the progression of neurodegenerative disease. Nat.Rev.Neurosci. 4:103-112

37. Platten M, Eitel K, Wischhusen J, Dichgans J, Weller M (2003) Involvement of protein kinase Cdelta and extracellular signal-regulated kinase-2 in the suppression of Microglial inducible nitric oxide synthase expression by N-[3,4-dimethoxycinnamoyl]-anthranilic acid (tranilast). Biochem.Pharmacol. 66:1263-1270
    Abstract: Excess nitric oxide (NO) in the brain released by Microglial cells contributes to neuronal damage in various pathologies of the central nervous system (CNS) including neurodegenerative diseases and multiple sclerosis. N-[3,4-Dimethoxycinnamoyl]-anthranilic acid (tranilast, TNL) is an anti-allergic compound which suppresses the activation of monocytes. We show that inducible nitric oxide synthase (iNOS) mRNA and protein expression and the release of NO from N9 Microglial cells stimulated with the bacterial endotoxin lipopolysaccharide (LPS) are inhibited when the cells are exposed to TNL. TNL fails to modulate LPS-stimulated nuclear factor-kappaB (NF-kappaB) reporter gene activity and phosphorylation of inhibitory kappaB (IkappaB), indicating that NF-kappaB is not involved in the TNL-mediated suppression of LPS-induced iNOS expression. Moreover, TNL inhibits LPS-induced phosphorylation of extracellular signal-regulated kinase 2 (ERK-2). Finally, TNL abolishes translocation of protein kinase Cdelta (PKCdelta) to the nucleus and suppresses the phosphorylation of the PKCdelta substrate, myristoylated alanin-rich C kinase substrate (MARCKS). We conclude that the anti-allergic compound TNL suppresses Microglial iNOS induction by LPS via inhibition of a signalling pathway involving PKCdelta and ERK-2

38. Rotshenker S (2003) Microglia and Macrophage Activation and the Regulation of Complement-Receptor-3 (CR3/MAC-1)-Mediated Myelin Phagocytosis in Injury and Disease. J.Mol.Neurosci. 21:65-72
    Abstract: Microglia and macrophages play critical roles in the response of the central and peripheral nervous systems (CNS and PNS, respectively) to injury and disease, one of which is the removal of degenerated myelin by phagocytosis. Myelin removal is efficient during Wallerian degeneration, which follows injury to PNS axons, and in CNS autoimmune demyelinating diseases (e.g., multiple sclerosis) but is inefficient after injury to CNS axons. We suggest that inefficient myelin removal results from deficient Microglia activation, reflected by the failure to up-regulate Galectin-3/MAC-2 expression, which marks a state of activation correlated with efficient myelin phagocytosis. Surprisingly, whether or not executing myelin phagocytosis, CNS Microglia express the alphaM/beta2 integrin complement receptor-3 (CR3/MAC-1), which has the potential of mediating efficient myelin phagocytosis. We hypothesize that CR3/MAC-1 might be present in distinct inactive and active states that determine, respectively, efficient and inefficient CR3/MAC-1-mediated myelin phagocytosis. We present evidence that CR3/MAC-1-mediated myelin phagocytosis is regulated in Microglia and macrophages. First, CR3/MAC-1- mediated myelin phagocytosis has complement-dependent and -independent components. Second, an active complement system augments CR3/MAC-1-mediated myelin phagocytosis. Third, anti-alphaM monoclonal antibodies (MAbs) inhibit and anti-beta2 MAbs augment CR3/MAC-1-mediated myelin phagocytosis in the presence and absence of an active complement system. Fourth, an active complement system modulates MAb-induced regulation of CR3/MAC-1-mediated myelin phagocytosis. Overall, MAb-induced phagocytosis regulation might range three- to sevenfold from inefficient to efficient. We suggest that one of the mechanisms underlying MAbinduced phagocytosis regulation is the induction/stabilization of inactive and active conformational changes. Monoclonal antibody-induced phagocytosis regulation must reveal a mechanism by which native extracellular molecules bind to and regulate CR3/MAC-1-mediated myelin phagocytosis in Microglia and macrophages

39. Schmidt J, Metselaar JM, Wauben MH, Toyka KV, Storm G, Gold R (2003) Drug targeting by long-circulating liposomal glucocorticosteroids increases therapeutic efficacy in a model of multiple sclerosis. Brain 126:1895-1904
    Abstract: High-dose glucocorticosteroid hormones are a mainstay in the treatment of relapses in multiple sclerosis. We searched for a way to deliver ultra high doses of glucocorticosteroids to the CNS of rats with experimental autoimmune encephalomyelitis (EAE) using a novel formulation of polyethylene glycol (PEG)-coated long-circulating liposomes encapsulating prednisolone (predni solone liposomes, PL). 3H-labelled PL showed selective targeting to the inflamed CNS, where up to 4.5-fold higher radioactivity was achieved than in healthy control animals. HPLC revealed much higher and more persistent levels of prednisolone in spinal cord after PL compared with an equal dose of free prednisolone. Gold-labelled liposomes could be detected in the target tissue, mostly taken up by macrophages (Mphi), Microglial cells and astrocytes. Blood-brain barrier disruption was greatly reduced by 10 mg/kg PL, which was superior to a 5-fold higher dose of free methylprednisolone (MP). PL was also superior to MP in diminishing T-cell infiltration by induction of T-cell apoptosis in spinal cord. Mphi infiltration was clearly decreased only by PL. The percentage of tumour necrosis factor-alpha (TNF-alpha)-positive T cells or Mphi was greatly reduced by PL and by MP. No adverse effects on glial cells were detected. A single injection of PL clearly ameliorated the course of adoptive transfer EAE and EAE induced by immunization. In conclusion, PL is a highly effective drug in treatment of EAE, and is superior to a 5-fold higher dose of free MP, possibly by means of drug targeting. These findings may have implications for future therapy of autoimmune disorders such as multiple sclerosis

40. Schroeter M, Stoll G, Weissert R, Hartung HP, Lassmann H, Jander S (2003) CD8+ phagocyte recruitment in rat experimental autoimmune encephalomyelitis: association with inflammatory tissue destruction. Am.J.Pathol. 163:1517-1524
    Abstract: Increasing evidence suggests an important role of CD8(+) cells in the pathogenesis of multiple sclerosis and its animal model experimental autoimmune encephalomyelitis (EAE). In our present study we analyzed the spatiotemporal expression pattern of the CD8 antigen in various rat EAE models characterized by a different extent of inflammation, demyelination, and axonal injury. Unexpectedly, in chronic demyelinating EAE induced by immunization against myelin oligodendrocyte glycoprotein (MOG) the majority of CD8 immunoreactivity was expressed on ED1(+) Microglia/macrophages whereas only limited CD8(+) T-cell infiltration was present. CD8(+) phagocyte recruitment was restricted to sites of severe inflammatory tissue destruction. Contrastingly, macrophages in a perivascular or submeningeal position and in secondarily degenerating fiber tracts were mostly CD8(-). CD8(+) phagocytes were absent in myelin basic protein-induced EAE characterized by a purely inflammatory pathology and lack of demyelination. Our data demonstrate significant heterogeneity of lesion-associated phagocytes in rat models of central nervous system autoimmune disease and suggest a specific role of CD8(+) Microglia/macrophages in the pathogenesis of inflammatory tissue damage

41. Stangel M, Bernard D (2003) Polyclonal IgM influence oligodendrocyte precursor cells in mixed glial cell cultures: implications for remyelination. J.Neuroimmunol. 138:25-30
    Abstract: Polyclonal immunoglobulins for intravenous use (IVIg) are a potent immunomodulator and have been shown to be effective in several immune-mediated diseases. This includes inflammatory demyelinating diseases of the central nervous system (CNS) like multiple sclerosis (MS). Besides their immunomodulatory function, IVIg have been proposed to enhance remyelination based on studies in the animal model of Theiler's murine encephalomyelitis virus (TMEV). Disappointingly, recent treatment trials in patients with MS have failed to demonstrate repair of longstanding deficits. Since the clinical trials have used IVIg that contained nearly exclusively IgG, whereas the most pronounced effect in TMEV was seen with IgM, this could be a possible explanation for the negative outcome in the MS trials. Here we have examined the effects of a new polyclonal IgM preparation (IVIgM) on cultured oligodendrocyte precursor cells (OPCs). To achieve successful remyelination, OPCs proliferate, migrate, and differentiate into mature myelinating oligodendrocytes. IVIgM and commercial IVIg preparations had no influence on proliferation and differentiation of either isolated OPCs or OPCs in coculture with Microglia. In contrast, IVIgM inhibited the proliferation of OPCs in mixed glial cultures containing astrocytes and Microglia. This was not seen in cultures treated with IVIg, albumin, or interferon-gamma (IFN-gamma), suggesting that this is a specific effect of IVIgM. Differentiation was slightly delayed by IVIgM in mixed glial cultures, but this was not statistically significant and interferon-gamma had a similar effect. These results underline the importance of IgM in influencing OPCs and corroborate the in vivo findings that polyclonal IgM are more potent than IgG in their capacity to influence remyelination. The exact mechanism of how this modulation of OPCs is achieved remains unknown, but a complex interaction among all cells present in the CNS has to be postulated

42. Takahashi JL, Giuliani F, Power C, Imai Y, Yong VW (2003) Interleukin-1beta promotes oligodendrocyte death through glutamate excitotoxicity. Ann.Neurol. 53:588-595
    Abstract: Glutamate excitotoxicity is implicated in the progressive loss of oligodendrocytes in multiple sclerosis, but how glutamate metabolism is dysregulated in the disease remains unclear. Because there is Microglia activation in all stages of multiple sclerosis, we determined whether a Microglia product, interleukin-1beta, could provide the mechanism for glutamate excitotoxicity. We found that whereas interleukin-1beta did not kill oligodendrocytes in pure culture, it produced apoptosis of oligodendrocytes in coculture with astrocytes and Microglia. This requirement for a mixed glia environment suggests that interleukin-1beta impairs the well-described glutamate-buffering capacity of astrocytes. In support, antagonists at AMPA/kainate glutamate receptors, NBQX and CNQX, blocked the interleukin-1beta toxicity to oligodendrocytes. Another Microglia/macrophage cytokine, tumor necrosis factor-alpha, also evoked apoptosis of oligodendrocytes in a mixed glia environment in an NBQX-blockable manner. These results provide a mechanistic link between the persistent and insidious Microglia activation that is evident in all stages of multiple sclerosis, with the recent appreciation that glutamate excitotoxicity leads to the destruction of oligodendrocytes in the disease

43. Taylor WR, Rasley A, Bost KL, Marriott I (2003) Murine gammaherpesvirus-68 infects Microglia and induces high levels of pro-inflammatory cytokine production. J.Neuroimmunol. 136:75-83
    Abstract: Murine gammaherpesvirus-68 (MHV-68) has been established as a tractable model for the study of human herpesvirus infections. Recent associations between herpesvirus infections and inflammatory central nervous system (CNS) disorders, including multiple sclerosis (MS), have prompted us to investigate the susceptibility of cultured Microglia and astrocytes to MHV-68 infection. In the present study, we demonstrate that MHV-68 can infect both cell types. Importantly, we show that MHV-68-infected Microglia and astrocytes can produce pro-inflammatory cytokines. Such cytokine production may either contribute to protective host responses to viral challenges or could exacerbate damaging CNS inflammation

44. Teige I, Treschow A, Teige A, Mattsson R, Navikas V, Leanderson T, Holmdahl R, Issazadeh-Navikas S (2003) IFN-beta gene deletion leads to augmented and chronic demyelinating experimental autoimmune encephalomyelitis. J.Immunol. 170:4776-4784
    Abstract: Since the basic mechanisms behind the beneficial effects of IFN-beta in multiple sclerosis (MS) patients are still obscure, here we have investigated the effects of IFN-beta gene disruption on the commonly used animal model for MS, experimental autoimmune encephalomyelitis (EAE). We show that IFN-beta knockout (KO) mice are more susceptible to EAE than their wild-type (wt) littermates; they develop more severe and chronic neurological symptoms with more extensive CNS inflammation and demyelination. However, there was no discrepancy observed between wt and KO mice regarding the capacity of T cells to proliferate or produce IFN-gamma in response to recall Ag. Consequently, we addressed the effect of IFN-beta on encephalitogenic T cell development and the disease initiation phase by passive transfer of autoreactive T cells from KO or wt littermates to both groups of mice. Interestingly, IFN-beta KO mice acquired a higher incidence and augmented EAE regardless of the source of T cells. This shows that the anti-inflammatory effect of endogenous IFN-beta is predominantly exerted on the effector phase of the disease. Histopathological investigations of CNS in the effector phase revealed an extensive Microglia activation and TNF-alpha production in IFN-beta KO mice; this was virtually absent in wt littermates. This coincided with an increase in effector functions of T cells in IFN-beta KO mice, as measured by IFN-gamma and IL-4 production. We suggest that lack of endogenous IFN-beta in CNS leads to augmented Microglia activation, resulting in a sustained inflammation, cytokine production, and tissue damage with consequent chronic neurological deficits

45. Trebst C, Staugaitis SM, Kivisakk P, Mahad D, Cathcart MK, Tucky B, Wei T, Rani MR, Horuk R, Aldape KD, Pardo CA, Lucchinetti CF, Lassmann H, Ransohoff RM (2003) CC chemokine receptor 8 in the central nervous system is associated with phagocytic macrophages. Am.J.Pathol. 162:427-438
    Abstract: CC chemokine receptor 8 (CCR8) has been detected in vitro on type 2 helper and regulatory lymphocytes, which might exert beneficial functions in multiple sclerosis (MS) and on macrophages and Microglia, possibly promoting tissue injury in MS lesions. To discriminate the relevant expression pattern in vivo, we defined the cell types that expressed CCR8 in MS lesions and determined the relationship of CCR8 expression and demyelinating activity. CCR8 was not expressed on T cells but was associated with phagocytic macrophages and activated Microglia in MS lesions and directly correlated with demyelinating activity. To identify factors associated with CCR8 expression, the study was extended to other central nervous system (CNS) pathologies. CCR8 was consistently expressed on phagocytic macrophages and activated Microglia in stroke and progressive multifocal leukoencephalopathy, but not expressed on Microglia in pathologies that lacked phagocytic macrophages such as senile change of the Alzheimer's type. CCR8 was up-regulated by macrophage differentiation and activating stimuli in vitro. In summary CNS CCR8 expression was associated with phagocytic macrophages and activated Microglial cells in human CNS diseases, suggesting that CCR8 may be a feasible target for therapeutic intervention in MS. CCR8 expression may also indicate a selective program of mononuclear phagocyte gene expression

46. Tsunoda I, Kuang LQ, Libbey JE, Fujinami RS (2003) Axonal injury heralds virus-induced demyelination. Am.J.Pathol. 162:1259-1269
    Abstract: Axonal pathology has been highlighted as a cause of neurological disability in multiple sclerosis. The Daniels (DA) strain of Theiler's murine encephalomyelitis virus infects the gray matter of the central nervous system of mice during the acute phase and persistently infects the white matter of the spinal cord during the chronic phase, leading to demyelination. This experimental infection has been used as an animal model for multiple sclerosis. The GDVII strain causes an acute fatal polioencephalomyelitis without demyelination. Injured axons were detected in normal appearing white matter at 1 week after infection with DA virus by immunohistochemistry using antibodies specific for neurofilament protein. The number of damaged axons increased throughout time. By 2 and 3 weeks after infection, injured axons were accompanied by parenchymal infiltration of Ricinus communis agglutinin I(+) Microglia/macrophages, but never associated with perivascular T-cell infiltration or obvious demyelination until the chronic phase. GDVII virus infection resulted in severe axonal injury in normal appearing white matter at 1 week after infection, without the presence of macrophages, T cells, or viral antigen-positive cells. The distribution of axonal injury observed during the early phase corresponded to regions where subsequent demyelination occurs during the chronic phase. The results suggest that axonal injury might herald or trigger demyelination

47. Versijpt J, Van Laere K, Dierckx RA, Dumont F, De Deyn PP, Slegers G, Korf J (2003) Scintigraphic visualization of inflammation in neurodegenerative disorders. Nucl.Med.Commun. 24:209-221
    Abstract: In the past few decades, our understanding of the central nervous system has evolved from one of an immune-privileged site, to one where inflammation is pathognomonic for some of the most prevalent and tragic neurodegenerative diseases. Current research indicates that diseases as diverse as multiple sclerosis, stroke and Alzheimer's disease exhibit inflammatory processes that contribute to cellular dysfunction or loss. Inflammation, whether in the brain or periphery, is almost always a secondary response to a primary pathogen. In head trauma, for example, the blow to the head is the primary event. What typically concerns the neurologist and neurosurgeon more, however, is the secondary inflammatory response that will ensue and likely cause more neuron loss than the initial injury. This paper reviews the basic neuroinflammatory mechanisms, the potential neurotoxic mediators during activation of Microglia, the brain resident macrophages, and their role in neurodegeneration. Alzheimer's disease is taken as a prototype for exploring these mechanisms, as it expresses more than 40 inflammatory mediators, it is the most extensively studied disorder in terms of immune-related pathogenesis, and because of its importance as the most prevalent type of dementia. Tools for the visualization of these neuroinflammatory processes, both structural and mainly functional, are critically reviewed and discussed

48. Vos CM, van Haastert ES, De Groot CJ, van d, V, de Vries HE (2003) Matrix metalloproteinase-12 is expressed in phagocytotic macrophages in active multiple sclerosis lesions. J.Neuroimmunol. 138:106-114
    Abstract: Matrix metalloproteinases (MMPs) are proteases involved in extracellular matrix (ECM) remodeling, leukocyte infiltration into lesions and myelin degradation in the central nervous system (CNS) disease multiple sclerosis (MS). We have investigated whether MMP-12 (macrophage metalloelastase) is expressed in MS lesions at various stages. In control patient tissue and (p)reactive MS lesions, only occasional Microglial and astrocyte staining was detected. In contrast, in active demyelinating lesions, phagocytic macrophages were MMP-12 positive. A lower proportion of phagocytes was positive for MMP-12 in chronic active demyelinating lesions and inactive lesions. This suggests a role for MMP-12 during demyelination in MS

49. Zehntner SP, Brisebois M, Tran E, Owens T, Fournier S (2003) Constitutive expression of a costimulatory ligand on antigen-presenting cells in the nervous system drives demyelinating disease. FASEB J. 17:1910-1912
    Abstract: It has been proposed that the activation status of antigen-presenting cells (APCs) plays a significant role in the development of autoimmune disease. Whether expression of costimulatory ligands on tissue-resident APCs controls organ-specific autoimmune responses has not been tested. We here report that transgenic mice constitutively expressing the costimulatory ligand B7.2/CD86 on Microglia in the central nervous system (CNS) and on related cells in the proximal peripheral nervous tissue spontaneously develop autoimmune demyelinating disease. Disease-affected nervous tissue in transgenic mice showed infiltration characterized by a predominance of CD8+ memory-effector T cells, as well as CD4+ T cells. Transgenic animals lacking alphabeta TCR+ T cells were completely resistant to disease development. Transgenic T cells induced disease when adoptively transferred into T cell-deficient B7.2 transgenic recipients but not into non-transgenic recipients. These data provide evidence that B7/CD28 interactions within the nervous tissue are critical determinants of disease development. Our findings have important implications for understanding the etiology of nervous system autoimmune diseases such as multiple sclerosis (MS) and Guillain-Barre syndrome (GBS)

50. Basu A, Krady JK, O'Malley M, Styren SD, DeKosky ST, Levison SW (2002) The type 1 interleukin-1 receptor is essential for the efficient activation of Microglia and the induction of multiple proinflammatory mediators in response to brain injury. J.Neurosci. 22:6071-6082
    Abstract: Interleukin-1 (IL-1) is induced immediately after insults to the brain, and elevated levels of IL-1 have been strongly implicated in the neurodegeneration that accompanies stroke, Alzheimer's disease, and multiple sclerosis. In animal models, antagonizing IL-1 has been shown to reduce cell death; however, the basis for this protection has not been elucidated. Here we analyzed the response to penetrating brain injury in mice lacking the type 1 IL-1 receptor (IL-1R1) to determine which cellular and molecular mediators of tissue damage require IL-1 signaling. At the cellular level, fewer amoeboid Microglia/macrophages appeared adjacent to the injured brain tissue in IL-1R1 null mice, and those Microglia present at early postinjury intervals retained their resting morphology. Astrogliosis also was mildly abrogated. At the molecular level, cyclooxygenase-2 (Cox-2) and IL-6 expression were depressed and delayed. Interestingly, basal levels of Cox-2, IL-1, and IL-6 were significantly lower in the IL-1R1 null mice. In addition, stimulation of vascular cell adhesion molecule-1 mRNA was depressed in the IL-1R1 null mice, and correspondingly, there was reduced diapedesis of peripheral macrophages in the IL-1R1 null brain after injury. This observation correlated with a reduced number of Cox-2+ amoeboid phagocytes adjacent to the injury. In contrast, several molecular aspects of the injury response were normal, including expression of tumor necrosis factor-alpha and the production of nerve growth factor. Because antagonizing IL-1 protects neural cells in experimental models of stroke and multiple sclerosis, our data suggest that cell preservation is achieved by abrogating Microglial/macrophage activation and the subsequent self-propagating cycle of inflammation

51. Bsibsi M, Ravid R, Gveric D, van Noort JM (2002) Broad expression of Toll-like receptors in the human central nervous system. J.Neuropathol.Exp.Neurol. 61:1013-1021
    Abstract: The family of Toll-like receptors (TLRs) plays a key role in controlling innate immune responses to a wide variety of pathogen-associated molecules. In this study we investigated expression of TLRs in vitro by purified human Microglia, astrocytes, and oligodendrocytes, and in vivo by immunohistochemical examination of brain and spinal cord sections. Cultured primary Microglia were found to express mRNA encoding a wide range of different TLR family members while astrocytes and oligodendrocytes primarily express TLR2 and TLR3. Comparisons between Microglia derived from a series of control subjects and neurodegenerative cases indicate distinct differences in levels of mRNA encoding the different TLRs indifferent Microglia samples. Interestingly, expression of TLR proteins in cultured Microglia as revealed by immunocytochemistry was restricted to intracellular vesicles, whereas in astrocytes they were exclusively localized on the cell surface. Finally, in vivo expression of TLR3 and TLR4 was examined by immunohistochemical analysis of brain and spinal cord sections from both control and multiple sclerosis brains, revealing enhanced expression of either TLR in inflamed CNS tissues. Together, our data reveal broad and regulated expression of TLRs both in vitro and in vivo by human glia cells

52. Cammer W (2002) Apoptosis of oligodendrocytes in secondary cultures from neonatal rat brains. Neurosci.Lett. 327:123-127
    Abstract: The plaques in multiple sclerosis (MS) autopsy tissue contain tumor necrosis factor-alpha (TNF-alpha) at high concentrations. Moreover, Microglia are able to convert L-tryptophan to quinolinic acid. Thus, TNF-alpha and quinolinic acid are endogenous compounds which may compromise oligodendrocytes during inflammatory demyelination. It is also known that cellular functions depend on adequate concentrations of glutathione (GSH). As some apoptotic oligodendrocytes have been observed in MS plaques, it was therefore logical to determine whether oligodendrocyte apoptosis would occur in response to TNF-alpha, quinolinic acid or GSH depletion. Oligodendrocytes were treated in vitro with TNF-alpha, quinolinic acid and the GSH-depleting agent, buthionine sulfoximine (BSO), respectively, and the numbers of intact and apoptotic cells were counted. TNF-alpha reduced the numbers of mature oligodendrocytes, but not immature oligodendrocytes, without producing apoptosis. Quinolinic acid and BSO each caused oligodendrocyte loss via apoptosis, and GSH ethyl ester partly protected the cells against BSO. The data suggest that oligodendrocytes undergo apoptosis under adverse conditions that result from an endogenous toxicant or depletion of GSH

53. Carson MJ (2002) Microglia as liaisons between the immune and central nervous systems: functional implications for multiple sclerosis. Glia 40:218-231
    Abstract: multiple sclerosis is a chronic demyelinating inflammatory disease of the central nervous system (CNS). As the tissue macrophage of the CNS, Microglia have the potential to regulate and be regulated by cells of the CNS and by CNS-infiltrating immune cells. The exquisite sensitivity of Microglia to these signals, coupled with their ability to develop a broad range of effector functions, allows the CNS to tailor Microglial function for specific physiological needs. However, the great plasticity of Microglial responses can also predispose these cells to amplify disproportionately the irrelevant or dysfunctional signals provided by either the CNS or immune systems. The consequences of such an event could be the conversion of self-limiting inflammatory responses into chronic neurodegeneration and may explain in part the heterogeneous nature of multiple sclerosis

54. Chabot S, Yong FP, Le DM, Metz LM, Myles T, Yong VW (2002) Cytokine production in T lymphocyte-Microglia interaction is attenuated by glatiramer acetate: a mechanism for therapeutic efficacy in multiple sclerosis. Mult.Scler. 8:299-306
    Abstract: The efficacy of glatiramer acetate in multiple sclerosis (MS) is thought to involve the production of Th2 regulatory lymphocytes that secrete anti-inflammatory cytokines; however, other mechanisms cannot be excluded Given that activated T lymphocytes infiltrate into the CNS and become in dose proximity to Microglia, we evaluated whether glatiramer acetate affects the potential interaction between T cells and Microglia. We report that the co-culture of activated T lymphocytes with Microglia led to the induction of several cytokines, and that these were reduced by glatiramer acetate treatment Morphological transformation of bipolar/ramified Microglia into an activated ameboid form was attenuated by glatiramer acetate. These results reveal a novel mechanism for glatiramer acetate: the impairment of activated T cells to effectively interact with Microglia to produce cytokines. The net result of a non-inflammatory milieu within the CNS, in spite of T cell infiltration, may help account for the amelioration of disease activity in MS patients on glatiramer acetate therapy

55. Columba-Cabezas S, Serafini B, Ambrosini E, Sanchez M, Penna G, Adorini L, Aloisi F (2002) Induction of macrophage-derived chemokine/CCL22 expression in experimental autoimmune encephalomyelitis and cultured Microglia: implications for disease regulation. J.Neuroimmunol. 130:10-21
    Abstract: Macrophage-derived chemokine (MDC/CCL22) and its receptor CCR4 have been implicated in chronic inflammatory processes and in the homing of monocytes, Th2 cells and regulatory T-cell subsets. Here, we demonstrate that MDC and CCR4 mRNAs are expressed in the central nervous system (CNS) of mice developing relapsing-remitting and chronic-relapsing forms of experimental autoimmune encephalomyelitis (EAE). By immunohistochemistry, we show that MDC is produced by CNS-infiltrating leukocytes and intraparenchymal Microglia, whereas CCR4 is expressed on some invading leukocytes. Upon in vitro activation, mouse Microglia express MDC transcripts and secrete bioactive MDC that induces chemotaxis of Th2, but not Th1 cells. We suggest that MDC produced by Microglia could regulate Th1-mediated CNS inflammation by facilitating the homing of Th2 and, possibly, regulatory T cells into the lesion site

56. Cosenza MA, Zhao ML, Shankar SL, Shafit-Zagardo B, Lee SC (2002) Up-regulation of MAP2e-expressing oligodendrocytes in the white matter of patients with HIV-1 encephalitis. Neuropathol.Appl.Neurobiol. 28:480-488
    Abstract: HIV-1 encephalitis (HIVE) is characterized by infection of macrophages and Microglial cells, diffuse gliosis, and damage to neuronal populations. The nature of the white matter damage in HIVE remains elusive, and little is known about the status of the oligodendrocyte in HIVE. We have recently described a novel isoform of microtubule-associated protein-2 (MAP2e), which is expressed transiently in developing oligodendrocytes during myelination, and in remyelinating oligodendrocytes in multiple sclerosis lesions. In this study, we tested the hypothesis that MAP2e expression would be increased in the white matter of HIVE. We analysed brain sections from patients with HIVE and controls (HIV+ and HIV-) by immunocytochemistry and found that MAP2e+ cells are significantly increased in HIVE (range, 5-167 cells per cm2) compared to controls (range, 1-25 cells per cm2). MAP2e+ cells were negative for GFAP, CD68, LN3, RCA-1, von Willebrand factor and HIV-1 p24, but positive for MBP or Luxol-Fast Blue, supporting their oligodendroglial lineage. A topographical association between MAP2e and HIV-1 p24 expression was noted, but not between MAP2e and beta-APP, a marker of damaged axons. Our results demonstrate that MAP2e can serve as a marker of white matter damage in HIVE and support the notion that oligodendrocyte damage/repair occurs during HIV-1 infection

57. D'Aversa TG, Weidenheim KM, Berman JW (2002) CD40-CD40L interactions induce chemokine expression by human Microglia: implications for human immunodeficiency virus encephalitis and multiple sclerosis. Am.J.Pathol. 160:559-567
    Abstract: CD40 is a protein on Microglia that is up-regulated with interferon (IFN)-gamma and is engaged by CD40L, found on CD4+ T cells, B cells, and monocytes. These interactions may be important in central nervous system inflammatory diseases. Microglia have been shown to be a source of chemokines, whose expression plays a key role in central nervous system pathologies. We examined the expression of CD40 on Microglia in human immunodeficiency virus (HIV) encephalitic brain, and the effects of CD40-CD40L interactions on the expression of chemokines by cultured Microglia. We found significantly increased numbers of CD40-positive Microglia in HIV-infected brain tissue. Treatment of cultured Microglia with IFN-gamma and CD40L increased expression of several chemokines. IFN-gamma- and CD40L-induced MCP-1 protein was mediated by activation of the ERK1/2 MAPK pathway, and Western blot analysis demonstrated phosphorylation of ERK1/2 upon stimulation of Microglia. In contrast, IFN-gamma- and CD40L-induced IP-10 protein production was mediated by the p38 MAPK pathway. Our data suggest a mechanism whereby CD40L+ cells can induce Microglia to secrete chemokines, amplifying inflammatory processes seen in HIV encephalitis and multiple sclerosis, and implicate CD40-CD40L interactions as a target for interventional strategies

58. Dasgupta S, Jana M, Liu X, Pahan K (2002) Myelin basic protein-primed T cells induce nitric oxide synthase in Microglial cells. Implications for multiple sclerosis. J.Biol.Chem. 277:39327-39333
    Abstract: The presence of autoreactive T cells recognizing self myelin antigens is necessary for the development of central nervous system autoimmune diseases such as multiple sclerosis (MS). The present study was undertaken to investigate the role of myelin basic protein (MBP)-primed T cells in the expression of inducible nitric oxide synthase (iNOS) in Microglial cells. MBP-primed T cells alone markedly induced the production of NO and the expression of iNOS protein and mRNA in mouse BV-2 Microglial cells. Similarly, MBP-primed T cells also induced the production of NO in mouse primary Microglia. This induction of NO production was primarily dependent on the contact between MBP-primed T cells and Microglia. The expression of very late antigen-4 (VLA-4) on the surface of MBP-primed T cells and inhibition of MBP-primed T cell-induced Microglial NO production by functional blocking of antibodies to the alpha(4) chain of VLA-4 (CD49d) suggest that VLA-4 integrin on MBP-primed T cells plays an important role in contact-mediated induction of iNOS. Since IFN-beta has been used to treat MS patients, we examined the effect of IFN-beta on MBP-primed T cell-induced the production of NO. Surprisingly, IFN-beta alone induced the production of NO in Microglial cells. However, the pretreatment of MBP-primed T cells with IFN-beta inhibited the expression of VLA-4 integrin on the surface of MBP-primed T cells and thereby inhibited the ability of those T cells to induce the production of NO in Microglial cells. This study illustrates a novel role of neuroantigen-primed T cells in inducing contact-mediated expression of iNOS in Microglial cells that may participate in the pathogenesis of MS

59. Debruyne JC, Van Laere KJ, Versijpt J, De Vos F, Eng JK, Strijckmans K, Santens P, Achten E, Slegers G, Korf J, Dierckx RA, De Reuck JL (2002) Semiquantification of the peripheral-type benzodiazepine ligand [11C]PK11195 in normal human brain and application in multiple sclerosis patients. Acta Neurol.Belg. 102:127-135
    Abstract: OBJECTIVES: [11C]PK11195 is a peripheral-benzodiazepine-receptor radioligand used for detection of Microglial inflammation. Normal uptake by means of semiquantification was measured in order to establish reference data. The applicability of this semiquantitative approach was tested in three multiple sclerosis patients. MATERIALS AND METHODS: Seven controls and three patients underwent MR and PET scanning. Coregistered static scans 40 minutes postinjection of [11C]PK11195 were used for assessment of relative ligand uptake by comparison to whole-brain uptake. RESULTS: For static scans acquired in near steady-state, the relative ligand uptake was significantly higher in gray matter structures as compared to the whole brain (ratio: 1.041 +/- 0.06, p = 0.036) whereas it was comparable in white matter (1.010 +/- 0.035). Intersubject reproducibility was 11.4% and 12.9% for white and grey matter. Intrasubject reproducibility was of the same order: 14.0% and 14.5% respectively. In two clinically active patients with Gadolinium-positive T1-weighted lesions on MRI the focal ligand uptake was significantly increased (1.36 and 1.14, p = 0.001). In one clinically stable patient, the uptake value corresponding with a T2-weighted MR lesion was not different from normal brain measurements. CONCLUSION: The current investigations show that normal brain uptake of [11C]PK11195 is very low and shows the feasibility of a semiquantitative method which can be applied to larger cohorts of patients subgroups

60. Diab A, Deng C, Smith JD, Hussain RZ, Phanavanh B, Lovett-Racke AE, Drew PD, Racke MK (2002) Peroxisome proliferator-activated receptor-gamma agonist 15-deoxy-Delta(12,14)-prostaglandin J(2) ameliorates experimental autoimmune encephalomyelitis. J.Immunol. 168:2508-2515
    Abstract: Peroxisome proliferator-activated receptors (PPAR) are members of a nuclear hormone receptor superfamily that includes receptors for steroids, retinoids, and thyroid hormone, all of which are known to affect the immune response. Previous studies dealing with PPAR-gamma expression in the immune system have been limited. Recently, PPAR-gamma was identified in monocyte/macrophage cells. In this study we examined the role of PPAR-gamma in experimental autoimmune encephalomyelitis (EAE), an animal model for the human disease multiple sclerosis. The hypothesis we are testing is whether PPAR-gamma plays an important role in EAE pathogenesis and whether PPAR-gamma ligands can inhibit the clinical expression of EAE. Initial studies have shown that the presence of the PPAR-gamma ligand 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ2) inhibits the proliferation of Ag-specific T cells from the spleen of myelin basic protein Ac(1-11) TCR-transgenic mice. 15d-PGJ2 suppressed IFN-gamma, IL-10, and IL-4 production by both Con A- and myelin basic protein Ac(1-11) peptide-stimulated lymphocytes as determined by ELISA and ELISPOT assay. Culture of encephalitogenic T cells with 15d-PGJ2 in the presence of Ag reduced the ability of these cells to adoptively transfer EAE. Examination of the target organ, the CNS, during the course of EAE revealed expression of PPAR-gamma in the spinal cord inflammatory infiltrate. Administration of 15d-PGJ2 before and at the onset of clinical signs of EAE significantly reduced the severity of disease. These results suggest that PPAR-gamma ligands may be a novel therapeutic agent for diseases such as multiple sclerosis

61. Dietrich JB (2002) The adhesion molecule ICAM-1 and its regulation in relation with the blood-brain barrier. J.Neuroimmunol. 128:58-68
    Abstract: The blood-brain barrier (BBB) is formed by high resistance tight junctions within the capillary endothelium perfusing the vertebrate brain. Normal BBB maintains a unique microenvironment within the central nervous system (CNS). In neurodegenerative disorders (for example multiple sclerosis, MS), the BBB becomes impaired. Perivascular cells (astrocytes, macrophages and Microglial cells) and brain microvascular endothelial cells (BMEC) produce various inflammatory factors that affect the BBB permeability and the expression of adhesion molecules. Indeed, cytokines can stimulate the expression of several adhesion molecules on brain microvascular endothelial cells. Among these adhesion molecules, the intercellular adhesion molecule-1 (ICAM-1) binds to its leukocyte ligands and allows activated leukocytes entry into the CNS.This review is dealing with the expression and regulation of ICAM-1 in relation with several properties of the BBB. Particularly, the role of ICAM-1 in the control of the leukocyte traffic into the CNS, as well as in cerebral malaria and in CNS infection by viruses, is discussed

62. Feinstein DL, Heneka MT, Gavrilyuk V, Dello RC, Weinberg G, Galea E (2002) Noradrenergic regulation of inflammatory gene expression in brain. Neurochem.Int. 41:357-365
    Abstract: It is now well accepted that inflammatory events contribute to the pathogenesis of numerous neurological disorders, including multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease, and AID's dementia. Whereas inflammation in the periphery is subject to rapid down regulation by increases in anti-inflammatory molecules and the presence of scavenging soluble cytokine receptors, the presence of an intact blood-brain barrier may limit a similar autoregulation from occurring in brain. Mechanisms intrinsic to the brain may provide additional immunomodulatory functions, and whose dysregulation could contribute to increased inflammation in disease. The findings that noradrenaline (NA) reduces cytokine expression in Microglial, astroglial, and brain endothelial cells in vitro, and that modification of the noradrenergic signaling system occurs in some brain diseases having an inflammatory component, suggests that NA could act as an endogenous immunomodulator in brain. Furthermore, accumulating studies indicate that modification of the noradrenergic signaling system occurs in some neurodiseases. In this article, we will briefly review the evidence that NA can modulate inflammatory gene expression in vitro, summarize data supporting a similar immunomodulatory role in brain, and present recent data implicating a role for NA in attenuating the cortical inflammatory response to beta amyloid protein

63. Feng X, Yau D, Holbrook C, Reder AT (2002) Type I interferons inhibit interleukin-10 production in activated human monocytes and stimulate IL-10 in T cells: implications for Th1-mediated diseases. J.Interferon Cytokine Res. 22:311-319
    Abstract: Type I interferons (IFNs) directly induce development of Th1 cells. However, IFN-alpha and IFN-beta should generate Th2 cells because these IFNs induce interleukin-10 (IL-10) and block secretion of IFN-gamma. We hypothesized that paradoxical effects of IFNs on Th1-mediated immunity could be from monocyte-specific and T cell-specific IL-10 regulation. We demonstrate that IFN-alpha and IFN-beta inhibit IL-10 mRNA and protein production by activated monocytes but stimulate IL-10 production by activated T cells from the same healthy donors. Without IFN-beta, Staphylococcus aureus, Cowan strain I (SAC)-activated monocytes secreted 15-fold more IL-10 than phorbol myristate acetate (PMA) anti-CD3-activated T cells. With IFN-beta, the two subsets had nearly equivalent secretion. Prostaglandin (PGE) and other cAMP agonists had subset-specific effects on IL-10 production opposite to IFN-beta. The differential IFN-beta effect on transcriptional regulation of IL-10 in monocytes and T cells was from lineage-specific modification of RNA stability. IFN-beta decreased the half-life of IL-10 mRNA in activated monocytes but prolonged the half-life in activated T cells. Subset-specific IL-10 regulation has important implications for Th1-mediated disease. When activated macrophages and Microglia are in excess, as in rheumatoid joints or possibly in chronic multiple sclerosis brain lesions, IFNs may inhibit overall IL-10 production and worsen disease. When T cells outnumber monocytes, IFN-beta will induce IL-10 and ameliorate Th1-mediated disease

64. Fiebich BL, Lieb K, Engels S, Heinrich M (2002) Inhibition of LPS-induced p42/44 MAP kinase activation and iNOS/NO synthesis by parthenolide in rat primary Microglial cells. J.Neuroimmunol. 132:18-24
    Abstract: Nitric oxide (NO) has been implicated in the etiopathology of central nervous system (CNS) diseases such as multiple sclerosis (MS). Inhibition of NO synthesis has been proposed to be a possible mechanism of action of relevance in the treatment of multiple sclerosis and migraine. Here, we investigated the effect of parthenolide on inducible NO synthase (iNOS) synthesis and NO release using primary rat Microglia. We found parthenolide to be an inhibitor of iNOS/NO synthesis. Investigating the molecular mechanisms by which parthenolide prevents iNOS/NO synthesis, we found that parthenolide inhibits the activation of p42/44 mitogen-activated protein kinase (MAPK), but not IkBalpha (IkappaBalpha) degradation or nuclear factor-kappaB (NF-kappaB) p65 activation. The data suggest that parthenolide might have a potential in the treatment of CNS diseases where NO is part of the pathophysiology

65. Filipovic R, Rakic S, Zecevic N (2002) Expression of Golli proteins in adult human brain and multiple sclerosis lesions. J.Neuroimmunol. 127:1-12
    Abstract: It has been suggested that Golli proteins, structurally related to myelin basic proteins (MBPs), have a role in autoimmune processes. We studied the expression of these proteins in multiple sclerosis (MS) and determined that the number of Golli-immunoreactive (ir) cells was significantly higher around lesions of chronic MS than in control white matter. Golli proteins were expressed in the adult oligodendrocyte precursor cells (OPCs), activated Microglia/macrophages, and some demyelinated axons around MS lesions. Their expression in adult OPCs indicates remyelination attempts, whereas the expression in the subpopulation of Microglia/macrophages suggests roles in the immune processes of MS. In addition, Golli proteins may be markers of axonal transection, which is characteristic for MS

66. Gran B, Zhang GX, Yu S, Li J, Chen XH, Ventura ES, Kamoun M, Rostami A (2002) IL-12p35-deficient mice are susceptible to experimental autoimmune encephalomyelitis: evidence for redundancy in the IL-12 system in the induction of central nervous system autoimmune demyelination. J.Immunol. 169:7104-7110
    Abstract: Experimental autoimmune encephalomyelitis (EAE) serves as a model for multiple sclerosis and is considered a CD4(+), Th1 cell-mediated autoimmune disease. IL-12 is a heterodimeric cytokine, composed of a p40 and a p35 subunit, which is thought to play an important role in the development of Th1 cells and can exacerbate EAE. We induced EAE with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55 (MOG(35-55)) in C57BL/6 mice and found that while IL-12p40-deficient (-/-) mice are resistant to EAE, IL-12p35(-/-) mice are susceptible. Typical spinal cord mononuclear cell infiltration and demyelination were observed in wild-type and IL-12p35(-/-) mice, whereas IL-12p40(-/-) mice had normal spinal cords. A Th1-type response to MOG(35-55) was observed in the draining lymph node and the spleen of wild-type mice. A weaker MOG(35-55)-specific Th1 response was observed in IL-12p35(-/-) mice, with lower production of IFN-gamma. By contrast, a Th2-type response to MOG(35-55) correlated with disease resistance in IL-12p40(-/-) mice. Production of TNF-alpha by Microglia, CNS-infiltrating macrophages, and CD4(+) T cells was detected in wild-type and IL-12p35(-/-), but not in IL-12p40(-/-), mice. In addition, NO production was higher in IL-12p35(-/-) and wild-type mice than in IL-12p40(-/-) mice. These data demonstrate a redundancy of the IL-12 system in the induction of EAE and suggest that p40-related heterodimers, such as the recently cloned IL-23 (p40p19), may play an important role in disease pathogenesis

67. Hulshof S, Montagne L, De Groot CJ, van d, V (2002) Cellular localization and expression patterns of interleukin-10, interleukin-4, and their receptors in multiple sclerosis lesions. Glia 38:24-35
    Abstract: Cytokines have been shown to play a crucial role in the pathogenesis of multiple sclerosis (MS). However, still limited data are available on the expression of anti-inflammatory cytokines within the central nervous system (CNS) during MS lesion development. Therefore, we have examined the expression of the anti-inflammatory cytokines, interleukin-10 (IL-10) and IL-4, and their specific receptors, IL-10R and IL-4R, in postmortem human brain tissue obtained from MS patients. Specific patterns of protein localization and expression for both proteins could be observed within active and chronic MS lesions. Strongest IL-10 immunoreactivity was observed in reactive astrocytes within active demyelinating lesions and the hypercellular rim of chronic active MS lesions. Moreover, perivascular macrophages were immunoreactive for IL-10 in (chronic) active MS lesions. Most intense IL-4 immunoreactivity was detected in reactive fibrillary astrocytes within the hypocellular regions of chronic active and chronic inactive MS lesions. Strong immunoreactivity for IL-10R and IL-4R was detected on macrophages in both parenchymal and perivascular areas and on reactive astrocytes in active and chronic MS lesions. Our results indicate that IL-10 and IL-4 have an active role in CNS immune responses. The specific patterns of protein localization and protein expression for both IL-10 and IL-4 in MS lesions at different stages of development suggest that these anti-inflammatory cytokines and their receptors participate in processes leading to the formation of chronic MS lesions

68. Iribarren P, Cui YH, Le Y, Wang JM (2002) The role of dendritic cells in neurodegenerative diseases. Arch.Immunol.Ther.Exp.(Warsz.) 50:187-196
    Abstract: Dendritic cells (DCs) are the most potent antigen-presenting cells (APCs) involved in the induction of adaptive immune responses. The presence of DCs in the central nervous system (CNS) and the active participation of the immune system in a variety of neurodegenerative diseases have been demonstrated. This review will discuss recent findings pertinent to DCs and other antigen-presenting cells in the CNS in health and disease states

69. Kim MO, Si Q, Zhou JN, Pestell RG, Brosnan CF, Locker J, Lee SC (2002) Interferon-beta activates multiple signaling cascades in primary human Microglia. J.Neurochem. 81:1361-1371
    Abstract: Microglia, the resident brain macrophages, are the principal cells involved in the regulation of inflammatory and antimicrobial responses in the CNS. Interferon-beta (IFNbeta) is an antiviral cytokine induced by viral infection or following non-specific inflammatory challenges of the CNS. Because of the well-known anti-inflammatory properties of IFNbeta, it is also used to treat multiple sclerosis, an inflammatory CNS disease. Despite the importance of IFNbeta signaling in CNS cells, little has been studied, particularly in Microglia. In this report, we investigated the molecular mechanisms underlying IFNbeta-induced beta-chemokine expression in primary human fetal Microglia. Multiple signaling cascades are activated in Microglia by IFNbeta, including nuclear factor-kappaB (NF-kappaB), activator protein-1 (AP-1) and Jak/Stat. IFNbeta induced IkappaBalpha degradation and NF-kappaB (p65:p50) DNA binding. Inhibition of NF-kappaB by either adenoviral transduction of a super repressor IkappaBalpha, or an antioxidant inhibitor of NF-kappaB reduced expression of the beta-chemokines, regulated upon activation, normal T-cell expressed and secreted (RANTES) and macrophage inflammatory protein (MIP)-1beta. IFNbeta also induced phosphorylation of extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase, and the MAP kinase kinase 1 (MEK1) inhibitor PD98059 dose-dependently inhibited beta-chemokine mRNA and protein expression. PD98059 did not inhibit NF-kappaB binding, demonstrating that ERK was not responsible for NF-kappaB activation. Two downstream targets of ERK were identified in Microglia: AP-1 and Stat1. IFNbeta induced AP-1 nuclear binding activity in Microglia and this was suppressed by PD98059. Additionally, IFNbeta induced Stat1 phosphorylation at both tyrosine 701 (Y701) and serine 727 (S727) residues. S727 phosphorylation of Stat1, which is known to be required for maximal transcriptional activation, was inhibited by PD98059. Our results demonstrating multiple signaling cascades initiated by IFNbeta in primary human Microglia are novel and have implications for inflammatory and infectious diseases of the CNS

70. Kuhlmann T, Lingfeld G, Bitsch A, Schuchardt J, Bruck W (2002) Acute axonal damage in multiple sclerosis is most extensive in early disease stages and decreases over time. Brain 125:2202-2212
    Abstract: multiple sclerosis is characterized morphologically by the key features demyelination, inflammation, gliosis and axonal damage. In recent years, it has become more evident that axonal damage is the major morphological substrate of permanent clinical disability. In our study, we investigated the occurrence of acute axonal damage determined by immunocytochemistry for amyloid precursor protein (APP) which is produced in neurones and accumulates at sites of recent axon transection or damage. The numbers of APP-positive axons in multiple sclerosis lesions were correlated with the disease duration and course. Most APP-positive axons were detected within the first year after disease onset, but acute axonal damage was also detected to a minor degree in lesions of patients with a disease duration of 10 years and more. This effect was not due to the lack of active demyelinating lesions in the chronic disease stage. Late remyelinated lesions (so-called shadow plaques) did not show signs of axon destruction. The number of inflammatory cells showed a decrease over time similar to that of the number of APP-positive axons. There was a significant correlation between the extent of axon damage and the numbers of CD8-positive cytotoxic T cells and macrophages/Microglia. Our results indicate that a putative axon-protective treatment should start as early as possible and include strategies preventing T cell/macrophage-mediated axon destruction and leading to remyelination of axons

71. Lehnardt S, Lachance C, Patrizi S, Lefebvre S, Follett PL, Jensen FE, Rosenberg PA, Volpe JJ, Vartanian T (2002) The toll-like receptor TLR4 is necessary for lipopolysaccharide-induced oligodendrocyte injury in the CNS. J.Neurosci. 22:2478-2486
    Abstract: The immediate or innate immune response is the first line of defense against diverse microbial pathogens and requires the expression of recently discovered toll-like receptors (TLRs). TLR4 serves as a specific receptor for lipopolysaccharide (LPS) and is localized on the surface of a subset of mammalian cells. Although innate immunity is a necessary host defense against microbial pathogens, the consequences of its activation in the CNS can be deleterious, as we show here in a developing neural model. We examined the major non-neuronal cell types in the CNS for expression of TLR4 and found that Microglia expressed high levels, whereas astrocytes and oligodendrocytes expressed none. Consistent with TLR4 expression solely in Microglia, we show that Microglia are the only CNS glial cells that bind fluorescently tagged lipopolysaccharide. Lipopolysaccharide led to extensive oligodendrocyte death in culture only under conditions in which Microglia were present. To determine whether TLR4 is necessary for lipopolysaccharide-induced oligodendrocyte death in mixed glial cultures, we studied cultures generated from mice bearing a loss-of-function mutation in the tlr4 gene. Lipopolysaccharide failed to induce oligodendrocyte death in such cultures, in contrast to the death induced in cultures from wild-type mice. Finally, stereotactic intracerebral injection of lipopolysaccharide into the developing pericallosal white matter of immature rodents resulted in loss of oligodendrocytes and hypomyelination and periventricular cysts. Our data provide a general mechanistic link between (1) lipopolysaccharide and similar microbial molecular motifs and (2) injury to oligodendrocytes and myelin as occurs in periventricular leukomalacia and multiple sclerosis

72. Little AR, Benkovic SA, Miller DB, O'Callaghan JP (2002) Chemically induced neuronal damage and gliosis: enhanced expression of the proinflammatory chemokine, monocyte chemoattractant protein (MCP)-1, without a corresponding increase in proinflammatory cytokines(1). Neuroscience 115:307-320
    Abstract: Enhanced expression of proinflammatory cytokines and chemokines has long been linked to neuronal and glial responses to brain injury. Indeed, inflammation in the brain has been associated with damage that stems from conditions as diverse as infection, multiple sclerosis, trauma, and excitotoxicity. In many of these brain injuries, disruption of the blood-brain barrier (BBB) may allow entry of blood-borne factors that contribute to, or serve as the basis of, brain inflammatory responses. Administration of trimethyltin (TMT) to the rat results in loss of hippocampal neurons and an ensuing gliosis without BBB compromise. We used the TMT damage model to discover the proinflammatory cytokines and chemokines that are expressed in response to neuronal injury. TMT caused pyramidal cell damage within 3 days and a substantial loss of these neurons by 21 days post dosing. Marked Microglial activation and astrogliosis were evident over the same time period. The BBB remained intact despite the presence of multiple indicators of TMT-induced neuropathology. TMT caused large increases in whole hippocampal-derived monocyte chemoattractant protein (MCP)-1 mRNA (1,000%) by day 3 and in MCP-1 (300%) by day 7. The mRNA levels for tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-6, cytokines normally expressed during the earliest stage of inflammation, were not increased up to 21 days post dosing. Lipopolysaccharide, used as a positive control, caused large inductions of cytokine mRNA in liver, as well as an increase in IL-1beta in hippocampus, but it did not result in the induction of astrogliosis. The data suggest that enhanced expression of the proinflammatory cytokines, TNF-alpha, IL-1beta and IL-6, is not required for neuronal and glial responses to injury and that MCP-1 may serve a signaling function in the damaged CNS that is distinct from its role in proinflammatory events

73. Liu B, Gao HM, Wang JY, Jeohn GH, Cooper CL, Hong JS (2002) Role of nitric oxide in inflammation-mediated neurodegeneration. Ann.N.Y.Acad.Sci. 962:318-331
    Abstract: Increasing evidence has suggested that inflammation in the brain is closely associated with the pathogenesis of several degenerative neurologic disorders, including Parkinson's disease, Alzheimer's diseases, multiple sclerosis, amyotrophic lateral sclerosis, and AIDS dementia. The hallmark of brain inflammation is the activation of glial cells, especially that of Microglia that produce a variety of proinflammatory and neurotoxic factors, including cytokines, fatty acid metabolites, free radicals--such as nitric oxide (NO) and superoxide. Excessive production of NO, as a consequence of nitric oxide synthase induction in activated glia, has been attributed to participate in neurodegeneration. Using primary mixed neuron-glia cultures and glia-enriched cultures prepared from embryonic rodent brain tissues, we have systemically studied the relationship between the production of NO and neurodegeneration in response to stimulation by the inflammagen lipopolysaccharide. This review summarizes our recent findings on the kinetics of NO generation, the relative contribution of Microglia and astrocytes to NO accumulation, the relationship between NO production and neurodegeneration, and points of intervention along the pathways associated with NO generation to achieve neuroprotection. We also describe our results relating to the effect of several opioid-related agents on Microglial activation and neuroprotection. Among these agents, the opioid receptor antagonist naloxone, especially its non-opioid enantiomer (+)-naloxone, promises to be of potential therapeutic value for the treatment of inflammation-related diseases

74. Lu W, Bhasin M, Tsirka SE (2002) Involvement of tissue plasminogen activator in onset and effector phases of experimental allergic encephalomyelitis. J.Neurosci. 22:10781-10789
    Abstract: Inflammation, demyelination, and neurodegeneration are pathological features of multiple sclerosis (MS). In the brains of MS patients, tissue plasminogen activator (tPA) mRNA and protein are upregulated, and changes in the levels of tPA correlate with progression of the disease. However, the role of tPA in MS is as yet unknown. tPA functions in the CNS in neuronal plasticity and cell death. tPA also mediates the activation of Microglia, the CNS "immune cells." In this study, we establish that tPA activity increases during major oligodendrocyte glycoprotein-induced experimental allergic encephalomyelitis (EAE) in normal mice. To explore the role of tPA in this disease as a model for MS, we have examined the EAE course and expression of histopathological markers in mice lacking tPA (tPA(-/-)). We find that tPA(-/-) mice have a delayed onset of EAE but then exhibit increased severity and delayed recovery from the neurological dysfunction. Demyelination and axon degeneration are delayed, Microglial activation is attenuated, and the production of chemokines is decreased. Our results suggest that tPA and activated Microglia have complex roles in MS/EAE, and that these roles are harmful during the onset of the disease but beneficial in the recovery phase. A temporally restricted attenuation of tPA activity could have therapeutic potential in the management of MS

75. Lucchinetti CF, Mandler RN, McGavern D, Bruck W, Gleich G, Ransohoff RM, Trebst C, Weinshenker B, Wingerchuk D, Parisi JE, Lassmann H (2002) A role for humoral mechanisms in the pathogenesis of Devic's neuromyelitis optica. Brain 125:1450-1461
    Abstract: Devic's disease [neuromyelitis optica (NMO)] is an idiopathic inflammatory demyelinating disease of the CNS, characterized by attacks of optic neuritis and myelitis. The mechanisms that result in selective localization of inflammatory demyelinating lesions to the optic nerves and spinal cord are unknown. Serological and clinical evidence of B cell autoimmunity has been observed in a high proportion of patients with NMO. The purpose of this study was to investigate the importance of humoral mechanisms, including complement activation, in producing the necrotizing demyelination seen in the spinal cord and optic nerves. Eighty-two lesions were examined from nine autopsy cases of clinically confirmed Devic's disease. Demyelinating activity in the lesions was immunocytochemically classified as early active (21 lesions), late active (18 lesions), inactive (35 lesions) or remyelinating (eight lesions) by examining the antigenic profile of myelin degradation products within macrophages. The pathology of the lesions was analysed using a broad spectrum of immunological and neurobiological markers, and lesions were defined on the basis of myelin protein loss, the geography and extension of plaques, the patterns of oligodendrocyte destruction and the immunopathological evidence of complement activation. The pathology was identical in all nine patients. Extensive demyelination was present across multiple spinal cord levels, associated with cavitation, necrosis and acute axonal pathology (spheroids), in both grey and white matter. There was a pronounced loss of oligodendrocytes within the lesions. The inflammatory infiltrates in active lesions were characterized by extensive macrophage infiltration associated with large numbers of perivascular granulocytes and eosinophils and rare CD3(+) and CD8(+) T cells. There was a pronounced perivascular deposition of immunoglobulins (mainly IgM) and complement C9neo antigen in active lesions associated with prominent vascular fibrosis and hyalinization in both active and inactive lesions. The extent of complement activation, eosinophilic infiltration and vascular fibrosis observed in the Devic NMO cases is more prominent compared with that in prototypic multiple sclerosis, and supports a role for humoral immunity in the pathogenesis of NMO. Based on this study, future therapeutic strategies designed to limit the deleterious effects of complement activation, eosinophil degranulation and neutrophil/macrophage/Microglial activation are worthy of further investigation

76. Magnus T, Chan A, Savill J, Toyka KV, Gold R (2002) Phagocytotic removal of apoptotic, inflammatory lymphocytes in the central nervous system by Microglia and its functional implications. J.Neuroimmunol. 130:1-9
    Abstract: Apoptotic cell death of inflammatory T cells is an established mechanism to terminate an autoimmune inflammatory response in the rodent and human central nervous system (CNS). The efficient clearance of apoptotic cells protects the tissue from leakage of potentially harmful substances from secondary necrotic cells. As the resident phagocyte, the Microglial cell is the primary candidate for the clearance of apoptotic lymphocytes. Furthermore, the phagocytosis of apoptotic cells is accompanied by a spectrum of anti-inflammatory effects. In this review, we focus on the mechanisms for removal of apoptotic inflammatory cells by Microglia in the central nervous system and their functional consequences

77. Minagar A, Shapshak P, Fujimura R, Ownby R, Heyes M, Eisdorfer C (2002) The role of macrophage/Microglia and astrocytes in the pathogenesis of three neurologic disorders: HIV-associated dementia, Alzheimer disease, and multiple sclerosis. J.Neurol.Sci. 202:13-23
    Abstract: Macrophage/Microglia (M phi) are the principal immune cells in the central nervous system (CNS) concomitant with inflammatory brain disease and play a significant role in the host defense against invading microorganisms. Astrocytes, as a significant component of the blood-brain barrier, behave as one of the immune effector cells in the CNS as well. However, both cell types may play a dual role, amplifying the effects of inflammation and mediating cellular damage as well as protecting the CNS. Interactions of the immune system, M phi, and astrocytes result in altered production of neurotoxins and neurotrophins by these cells. These effects alter the neuronal structure and function during pathogenesis of HIV-1-associated dementia (HAD), Alzheimer disease (AD), and multiple sclerosis (MS). HAD primarily involves subcortical gray matter, and both HAD and MS affect sub-cortical white matter. AD is a cortical disease. The process of M phi and astrocytes activation leading to neurotoxicity share similarities among the three diseases. Human Immunodeficiency Virus (HIV)-1-infected M phi are involved in the pathogenesis of HAD and produce toxic molecules including cytokines, chemokines, and nitric oxide (NO). In AD, M phis produce these molecules and are activated by beta-amyloid proteins and related oligopeptides. Demyelination in MS involves M phi that become lipid laden, spurred by several possible antigens. In these three diseases, cytokine/chemokine communications between M phi and astrocytes occur and are involved in the balance of protective and destructive actions by these cells. This review describes the role of M phi and astrocytes in the pathogenesis of these three progressive neurological diseases, examining both beneficent and deleterious effects in each disease

78. Ming X, Li W, Maeda Y, Blumberg B, Raval S, Cook SD, Dowling PC (2002) Caspase-1 expression in multiple sclerosis plaques and cultured glial cells. J.Neurol.Sci. 197:9-18
    Abstract: Caspase-1 is responsible for processing inflammatory cytokines and is associated with the induction of apoptosis. Using RT-PCR, we found that caspase-1 mRNA transcripts from frozen brain extracts were significantly elevated in multiple sclerosis (MS) compared to controls. Immunohistochemical staining using a specific antiserum confirmed the marked up regulation of caspase-1 within acute and chronic MS plaques, while little staining was seen in control brains. In addition to the expected caspase-1 expression in Microglia and infiltrating perivascular mononuclear cells, we found that cytoplasmic caspase-1 expression was sharply increased in the resident oligodendrocytes of MS lesions. The TUNEL reaction for fragmented DNA co-localized over an occasional caspase-1-expressing cell and large numbers of caspase-1-positive "corpses" were observed within phagocytic macrophages of an acute evolving MS lesion. Studies using an immortalized human oligodendroglial hybrid cell line exposed to cytokine challenge showed that death induction was blocked by the caspase-1-like inhibitor Z-YVAD-fmk, while the caspase-3-like inhibitor Z-DEVD-fmk was less effective. Cellular levels of procaspase-1 were reduced compared to controls in oligodendroglia induced to die by cytokine challenge, as judged by Western immunoblotting. Our results suggest that caspase-1 may play a role in the inflammatory and apoptotic processes associated with MS pathogenesis

79. Nakamura Y (2002) Regulating factors for Microglial activation. Biol.Pharm.Bull. 25:945-953
    Abstract: Microglia, residential macrophages in the central nervous system, can release a variety of factors including cytokines, chemokines, etc. to regulate the communication among neuronal and other types of glial cells. Microglia play immunological roles in mechanisms underlying the phagocytosis of invading microorganisms and removal of dead or damaged cells. When Microglia are hyperactivated due to a certain pathological imbalance, they may cause neuronal degeneration. Pathological activation of Microglia has been reported in a wide range of conditions such as cerebral ischemia, Alzheimer's disease, prion diseases, multiple sclerosis, AIDS dementia, and others. Nearly 5000 papers on Microglia can be retrieved on the Web site PubMed at present (November 2001) and half of them were published within the past 5 years. Although it is not possible to read each paper in detail, as many factors as possible affecting Microglial functions in in vitro culture systems are presented in this review. The factors are separated into "activators" and "inhibitors," although it is difficult to classify many of them. An overview on these factors may help in the development of a new strategy for the treatment of various neurodegenerative diseases

80. Natarajan C, Bright JJ (2002) Curcumin inhibits experimental allergic encephalomyelitis by blocking IL-12 signaling through Janus kinase-STAT pathway in T lymphocytes. J.Immunol. 168:6506-6513
    Abstract: Experimental allergic encephalomyelitis (EAE) is a CD4(+) Th1 cell-mediated inflammatory demyelinating autoimmune disease of the CNS that serves as an animal model for multiple sclerosis (MS). IL-12 is a proinflammatory cytokine that plays a crucial role in the induction of neural Ag-specific Th1 differentiation and pathogenesis of CNS demyelination in EAE and MS. Curcumin (1,7-Bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione) is a naturally occurring polyphenolic phytochemical isolated from the rhizome of the medicinal plant Curcuma longa. It has profound anti-inflammatory activity and been traditionally used to treat inflammatory disorders. In this study we have examined the effect and mechanism of action of curcumin on the pathogenesis of CNS demyelination in EAE. In vivo treatment of SJL/J mice with curcumin significantly reduced the duration and clinical severity of active immunization and adoptive transfer EAE. Curcumin inhibited EAE in association with a decrease in IL-12 production from macrophage/Microglial cells and differentiation of neural Ag-specific Th1 cells. In vitro treatment of activated T cells with curcumin inhibited IL-12-induced tyrosine phosphorylation of Janus kinase 2, tyrosine kinase 2, and STAT3 and STAT4 transcription factors. The inhibition of Janus kinase-STAT pathway by curcumin resulted in a decrease in IL-12-induced T cell proliferation and Th1 differentiation. These findings highlight the fact that curcumin inhibits EAE by blocking IL-12 signaling in T cells and suggest its use in the treatment of MS and other Th1 cell-mediated inflammatory diseases

81. Natarajan C, Bright JJ (2002) Peroxisome proliferator-activated receptor-gamma agonists inhibit experimental allergic encephalomyelitis by blocking IL-12 production, IL-12 signaling and Th1 differentiation. Genes Immun. 3:59-70
    Abstract: Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a nuclear receptor transcription factor that regulates adipocyte differentiation and glucose homeostasis. PPARgamma agonists are potent therapeutic agents for the treatment of type 2 diabetes and obesity. PPARgamma agonists also prevent inflammation in animal models, suggesting their use for the treatment of human inflammatory diseases. Experimental allergic encephalomyelitis (EAE) is a Th1 cell-mediated inflammatory demyelinating disease model of multiple sclerosis (MS) and IL-12 plays a crucial role in the pathogenesis of EAE and MS. In this study we have examined the effect of PPARgamma agonists on the pathogenesis of EAE. In vivo treatment of SJL/J mice with PPARgamma agonists, 15-deoxydelta(12,14) prostaglandin J2 or Ciglitazone, decreased the duration and clinical severity of active immunization and adoptive transfer models of EAE. PPARgamma agonists inhibited EAE in association with a decrease in IL-12 production and differentiation of neural antigen-specific Th1 cells. In vitro treatment of activated T cells with PPARgamma agonists inhibited IL-12-induced activation of JAK-STAT signaling pathway and Th1 differentiation. These findings highlight the fact that PPARgamma agonists regulate central nervous system inflammation and demyelination by inhibiting IL-12 production, IL-12 signaling and Th1 differentiation in EAE

82. Nelson PT, Soma LA, Lavi E (2002) Microglia in diseases of the central nervous system. Ann.Med. 34:491-500
    Abstract: Microglia (MG) are enigmatic cells of the central nervous system (CNS). MG are morphologically, antigenically and functionally flexible, and have the potential for mobility and proliferation. MG are professional antigen-presenting cells and constitute part of the local CNS innate immune system, communicating with other immune cells via chemokines, cytokines and growth factors. MG contain several antigenic and functional markers similar to macrophages and dendritic cells (DCs), but also present several differences from DCs. The exact role(s) played by MG in the normal human CNS is the topic of lively debate. MG participate in many reactive processes in the CNS and are therefore an integral part of lesions in a variety of pathologic conditions. It is thought that MG may exacerbate diverse neurological conditions, including viral encephalitis, AIDS, multiple sclerosis (MS) and Alzheimer's disease. A recurrent theme is the perpetuation by MG of pathological cycles of monocyte recruitment, activation and cytopathic secretions, and/or auto antigen presentation

83. Nguyen VT, Benveniste EN (2002) Critical role of tumor necrosis factor-alpha and NF-kappa B in interferon-gamma -induced CD40 expression in Microglia/macrophages. J.Biol.Chem. 277:13796-13803
    Abstract: CD40 is a member of the tumor necrosis factor (TNF) receptor superfamily. CD40 expression on antigen-presenting cells (including macrophages and Microglia) is crucial for T-cell activation. Aberrant expression of CD40 has been associated with autoimmune inflammatory diseases such as multiple sclerosis and rheumatoid arthritis. We have recently shown that the cytokine interferon (IFN)-gamma is the most potent inducer of CD40 expression in macrophages and Microglia, and this induction is mediated by the IFN-gamma-activated transcription factor STAT-1alpha and constitutively expressed PU.1 and/or Spi-B. In this study, we have discovered that a major component of IFN-gamma-induced CD40 expression involves the endogenous production of the cytokine TNF-alpha. The inclusion of anti-TNF-alpha-neutralizing antibody significantly inhibits IFN-gamma-induced CD40 mRNA and CD40 promoter activity. IFN-gamma-induced CD40 protein expression is attenuated in TNF-alpha-deficient Microglia and can be restored with exogenous TNF-alpha. Site-directed mutagenesis studies demonstrate that three of the four NF-kappaB elements in the CD40 promoter are required for IFN-gamma-induced CD40 promoter activity. IFN-gamma treatment leads to the activation of NF-kappaB in a time-dependent manner, which is inhibited in the presence of anti-TNF-alpha-neutralizing antibody. These results indicate that IFN-gamma-induced TNF-alpha production and subsequent NF-kappaB activation are integral parts of the mechanism of IFN-gamma-induced CD40 expression

84. O'Keefe GM, Nguyen VT, Benveniste EN (2002) Regulation and function of class II major histocompatibility complex, CD40, and B7 expression in macrophages and Microglia: Implications in neurological diseases. J.Neurovirol. 8:496-512
    Abstract: The ability of Microglia, the brain's resident macrophage, to present antigen through the class II major histocompatibility complex (MHC) to T cells allows these normally quiescent cells to play a critical role in shaping the outcome of many neurological diseases. The expression of class II MHC antigens and the costimulatory molecules CD40 and B7 on Microglia and infiltrating macrophages is regulated through a complex network of cytokines in the inflamed brain. In this review, we describe the molecular mechanisms underlying class II MHC, CD40 and B7 regulation in Microglia and macrophages. Our focus is on the cis-elements in the promoters of their genes and the transcription factors activated by cytokines that bind them. The functional implications of aberrant class II MHC, CD40 and B7 expression by Microglia and macrophages as related to the diseases of multiple sclerosis and Alzheimer's Disease are discussed

85. Owens T (2002) Identification of new therapeutic targets for prevention of CNS inflammation. Expert.Opin.Ther.Targets. 6:203-215
    Abstract: multiple sclerosis (MS) is a disease of complex pathologies, which involves infiltration by CD4(+) and CD8(+) T cells of and response within the central nervous system. Expression in the CNS of cytokines, reactive nitrogen species and costimulator molecules have all been described in MS. Notably, the cytokines IFN-gamma and TNF are strongly expressed. Microglial cells in the CNS express costimulator molecules and it is assumed that they play a role in directing or inducing the T cell response. Transgenic experiments have tested the effects of overexpression of these molecules in mice and have shown that TNF has multiple effects in the CNS. These range from pro-inflammatory effects of soluble TNF signalling through one of its receptors TNF-RI, to protective/regenerative effects of membrane-associated TNF signalling through the other receptor, TNF-RII. Although IFN-gamma induces nitric oxide production via the enzyme inducible nitric oxide synthase, which is immunosuppressive, IFN-gamma is predominantly pro-inflammatory. In CNS disease in mice that involves CD8(+) T cells, IFN-gamma blockade is protective. Finally, Microglial expression of the costimulator ligand B7.2 induces demyelinating pathology. Animal experiments therefore point to IFN-gamma and costimulatory Microglia as logical targets of therapy for MS. IFN-gamma represents a more accessible target and should therefore be pursued at the earliest opportunity

86. Peterson JW, Bo L, Mork S, Chang A, Ransohoff RM, Trapp BD (2002) VCAM-1-positive Microglia target oligodendrocytes at the border of multiple sclerosis lesions. J.Neuropathol.Exp.Neurol. 61:539-546
    Abstract: The distribution and lineage of vascular cell adhesion molecule-1 (VCAM-1)-positive cells was investigated in 43 lesions from the brain tissue of patients with multiple sclerosis (MS). Numerous VCAM-1-positive macrophages/Microglia were detected at the edges of MS lesions. Quantitative analysis of 6 active, 7 chronic active, and 4 chronic inactive MS lesions identified most VCAM-1-positive cells at the actively demyelinating borders of active (102/mm3) and chronic active (29/mm3) lesions, but rarely in chronic inactive lesions (4/mm3). Further, approximately 17% of the VCAM-1-positive cells closely apposed or surrounded oligodendrocyte perikarya at the edges of active and chronic active lesions that were sites of ongoing demyelination. Endothelial cells were VCAM-1-negative in both lesion and non-lesion MS brain tissue. This report is the first to document direct Microglial interaction with oligodendrocytes in MS

87. Plumb J, McQuaid S, Mirakhur M, Kirk J (2002) Abnormal endothelial tight junctions in active lesions and normal-appearing white matter in multiple sclerosis. Brain Pathol. 12:154-169
    Abstract: Blood-brain barrier (BBB) breakdown, demonstrable in vivo by enhanced MRI is characteristic of new and expanding inflammatory lesions in relapsing-remitting and chronic progressive multiple sclerosis (MS). Subtle leakage may also occur in primary progressive MS. However, the anatomical route(s) of BBB leakage have not been demonstrated. We investigated the possible involvement of interendothelial tight junctions (TJ) by examining the expression of TJ proteins (occludin and ZO-1 ) in blood vessels in active MS lesions from 8 cases of MS and in normal-appearing white (NAWM) matter from 6 cases. Blood vessels (10-50 per frozen section) were scanned using confocal laser scanning microscopy to acquire datasets for analysis. TJ abnormalities manifested as beading, interruption, absence or diffuse cytoplasmic localization of fluorescence, or separation of junctions (putative opening) were frequent (affecting 40% of vessels) in oil-red-O-positive active plaques but less frequent in NAWM (15%), and in normal (< 2%) and neurological controls (6%). Putatively "open" junctions were seen in vessels in active lesions and in microscopically inflamed vessels in NAWM. Dual fluorescence revealed abnormal TJs in vessels with pre-mortem serum protein leakage. Abnormal or open TJs, associated with inflammation may contribute to BBB leakage in enhancing MRI lesions and may also be involved in subtle leakage in non-enhancing focal and diffuse lesions in NAWM. BBB disruption due to tight junctional pathology should be regarded as a significant form of tissue injury in MS, alongside demyelination and axonopathy

88. Popovic N, Schubart A, Goetz BD, Zhang SC, Linington C, Duncan ID (2002) Inhibition of autoimmune encephalomyelitis by a tetracycline. Ann.Neurol. 51:215-223
    Abstract: We have explored the use of minocycline, a tetracycline with antiinflammatory properties, to treat chronic relapsing-remitting experimental allergic encephalomyelitis, an animal model of multiple sclerosis. Therapeutic treatment with minocycline dramatically suppresses ongoing disease activity and limits disease progression. Disease suppression is associated with immune deviation in the periphery and with suppression of the inflammatory cascade in the central nervous system. This association is demonstrated by inhibition of Microglial activation and metalloproteinase-2 expression, which results in a concomitant decrease in inflammation and demyelination. As an established antiinflammatory drug with neuroprotective properties, minocycline may provide a novel therapeutic agent for relapsing-remitting multiple sclerosis

89. Pul R, Nguyen D, Schmitz U, Marx P, Stangel M (2002) Comparison of intravenous immunoglobulin preparations on Microglial function in vitro: more potent immunomodulatory capacity of an IgM/IgA-enriched preparation. Clin.Neuropharmacol. 25:254-259
    Abstract: Intravenous immunoglobulins (IVIg) have been used successfully as an immunomodulating treatment for patients with inflammatory diseases of the central nervous system (CNS) including multiple sclerosis (MS). It was shown previously that IVIg could modulate the functions of Microglia, the main immune cell in the CNS. We have compared five commercially available IVIg preparations on their capacity to modulate tumor necrosis factor (TNF)-alpha secretion and nitric oxide production in cultured Microglia. All preparations induced a dose-dependent stimulation of TNF-alpha secretion as measured by ELISA. There were some small differences between preparations consisting of IgG, while the preparation enriched for IgM and IgA induced a considerably higher TNF-alpha production at 1 mg/mL and 10 mg/mL. Similar results were seen for nitric oxide production as measured indirectly by the Griess reaction. These results indicate that IgM/IgA-enriched IVIg may be a more potent immunomodulator than pure IgG preparations on inflammatory reactions in the CNS

90. Reiman R, Gerard C, Campbell IL, Barnum SR (2002) Disruption of the C5a receptor gene fails to protect against experimental allergic encephalomyelitis. Eur.J.Immunol. 32:1157-1163
    Abstract: Activation of the complement system generates the anaphylatoxic peptide C5a, which elicits a broad range of inflammatory activities. The biological activities of C5a are mediated through its binding to the widely expressed C5a receptor (C5aR), a G-protein-coupled seven transmembrane domain receptor. In experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis, the C5aR is expressed on monocytes/macrophages, reactive astrocytes and T cells infiltrating the central nervous system (CNS). To investigate the role of the C5aR in this T cell-driven autoimmune model, we induced EAE in C5aR-deficient mice (C5aR(-/-)) and wild-type mice using a myelin oligodendrocyte glycoprotein (MOG) peptide as the immunogen. We found that C5aR(-/-) mice were fully susceptible to MOG-induced EAE with no difference in disease onset or severity in C5aR(-/-) mice compared to control mice. Cellular infiltrates (macrophages and T cells) were similar in the spinal cords of both animal groups and splenic T cells from C5aR(-/-) mice and control mice responded identically to MOG in T cell proliferation assays. Ribonuclease protection assays demonstrated no significant differences in pro-inflammatory gene expression between receptor-deficient and sufficient mice. These results indicate that the C5aR is not an essential mediator in the induction and progression of EAE

91. Reynolds R, Dawson M, Papadopoulos D, Polito A, Di Bello IC, Pham-Dinh D, Levine J (2002) The response of NG2-expressing oligodendrocyte progenitors to demyelination in MOG-EAE and MS. J.Neurocytol. 31:523-536
    Abstract: Remyelination of primary demyelinated lesions is a common feature of experimental models of multiple sclerosis (MS) and is also suggested to be the normal response to demyelination during the early stages of MS itself. Many lines of evidence have shown that remyelination is preceded by the division of endogenous oligodendrocyte precursor cells (OPCs) in the lesion and its borders. It is suggested that this rapid response of OPCs to repopulate the lesion site and their subsequent differentiation into new oligodendrocytes is the key to the rapid remyelination. Antibodies to the NG2 chondroitin sulphate proteoglycan have proved exceedingly useful in following and quantitating the response of endogenous OPCs to demyelination. Here we review the literature on the response of NG2-expressing OPCs to demyelination and provide some new evidence on their response to the chronic inflammatory demyelinating environment seen in recombinant myelin oligodendrocyte glycoprotein (MOG) induced experimental allergic encephalomyelitis (EAE) in the DA rat. NG2-expressing OPCs responded to the inflammatory demyelination in this model by becoming reactive and increasing in number in a very focal manner. Evidence of NG2+ OPCs in lesioned areas beginning to express the oligodendrocyte marker CNP was also seen. The response of OPCs appeared to occur following successive relapses but did not always lead to remyelination, with areas of chronic demyelination observed in the spinal cord. The presence of OPCs in the adult human CNS is clearly of vital importance for repair in multiple sclerosis (MS). As in rat tissue, the antibody labels an evenly distributed cell population present in both white and grey matter, distinct from HLA-DR+ Microglia. NG2+ cells are sparsely distributed in the centre of chronic MS lesions. These cells apparently survive demyelination and exhibit a multi-processed or bipolar morphology in the very hypocellular environment of the lesion

92. Schaecher K, Rocchini A, Dinkins J, Matzelle DD, Banik NL (2002) Calpain expression and infiltration of activated T cells in experimental allergic encephalomyelitis over time: increased calpain activity begins with onset of disease. J.Neuroimmunol. 129:1-9
    Abstract: Calpain activity and expression at the protein level were examined in inflammatory cells, activated Microglia, and astrocytes prior to or at onset of symptomatic experimental allergic encephalomyelitis (EAE), an animal model for the human demyelinating disease multiple sclerosis (MS). EAE was induced in Lewis rats by injection of guinea pig spinal cord homogenate and myelin basic protein (MBP) emulsified with Complete Freund's Adjuvant (CFA). Calpain translational expression, determined by Western blot and immunocytochemistry, was correlated with calpain activity, infiltration of inflammatory cells, and myelin loss at 2-11 days following challenge with antigen. Controls (CFA only) did not show any changes over time in these parameters and very few changes (CD11+ Microglia/mononuclear phagocytes) were seen in either group from days 2 to 8 post-induction. In contrast, from days 9 to 11, the animals that developed the disease (at least grade 1) demonstrated extensive cellular infiltration (CD4+, CD25+, and CD11+ as well as increased calpain expression (content) and activity. This study demonstrates that cell infiltration and increased calpain activity do not begin in the CNS until the onset of clinical signs

93. Schmid CD, Sautkulis LN, Danielson PE, Cooper J, Hasel KW, Hilbush BS, Sutcliffe JG, Carson MJ (2002) Heterogeneous expression of the triggering receptor expressed on myeloid cells-2 on adult murine Microglia. J.Neurochem. 83:1309-1320
    Abstract: Microglial activation is an early and common feature of almost all neuropathologies, including multiple sclerosis, Alzheimer's disease and mechanical injury. To better understand the relative contributions Microglia make toward neurodegeneration and neuroprotection, we used TOGA(R) to identify molecules expressed by Microglia and regulated by inflammatory signals. Triggering receptor expressed on myeloid cells-2 (TREM-2) was among the mRNAs identified as being expressed by unactivated Microglia, but down-regulated by lipopolysaccharide/interferon gamma. In the healthy CNS, not all Microglia expressed TREM-2. Microglial expression of TREM-2 varied not only between brain regions but also within each brain region. Brain regions with an incomplete blood-brain barrier had the lowest percentages of TREM-2- expressing Microglia, whereas the lateral entorhinal and cingulate cortex had the highest percentages. A novel form of TREM-2b that lacked a transmembrane domain was detected, perhaps indicating a soluble form of the protein. Taken together, these data suggest that (1) subsets of Microglia are specialized to respond to defined extracellular signals; and (2) regional variations in TREM-2 expression may contribute to the varying sensitivities of different brain regions to similar pathological signals

94. Schwab C, McGeer PL (2002) Complement activated C4d immunoreactive oligodendrocytes delineate small cortical plaques in multiple sclerosis. Exp.Neurol. 174:81-88
    Abstract: C4d-immunoreactive complement-activated oligodendrocytes (C4d-CAOs) have been described in several neurodegenerative diseases but have not been studied in multiple sclerosis (MS). Here we report that such CAOs delineate miniature MS plaques of 300-500 mum diameter. They are devoid of myelin and are surrounded by a rim of activated Microglia intermingled with the C4d-CAOs. Although C4d-immunostained periaxonal oligodendroglial processes are often swollen, the axons of passage appear undamaged and extend through the demyelinated plaque area. No immunostaining with other components of the complement cascade (C1q-C9) was observed in association with these miniature plaques. However, in large MS lesions, C1q-C9 immunoreactive fibers were present, indicating complete activation of the complement cascade in these more developed lesions. It is possible that the miniature plaques, bordered by C4d-CAOs, represent the earliest stage of plaque development, preceding even the larger, transient plaques frequently observed in serial MRI studies. The association of CAOs with miniature areas of demyelination suggests a direct attack on oligodendroglial cells by the early complement components as an initiating event in MS. Incomplete complement activation indicates that this step may be reversible, whereas full and persistent activation as observed in large MS lesions may lead to death of oligodendroglia with permanent axonal damage

95. Siao CJ, Tsirka SE (2002) Extracellular proteases and neuronal cell death. Cell Mol.Biol.(Noisy.-le-grand) 48:151-161
    Abstract: Neuronal cell death occurs during development of the central nervous system as well as in pathological situations such as acute injury and progressive degenerative diseases. For instance, granule cells in the developing cerebellum and neuronal precursor cells in the cortex undergo programmed cell death, or apoptosis. There is currently strong debate conceming the mechanism of death in many degenerative events such as ischemia, blunt head trauma, excitotoxicity and neurodegenerative diseases, i.e. Alzheimer's disease. Neurons can die a necrotic death when the initial insult is too great; apoptosis requires "planning." For example, the cell death seen in the core of an ischemic infarct is necrotic, while in the surrounding penumbra region the death is probably apoptotic. Regardless of the degenerative pathway, damaged or dead neurons are a hallmark of many diseases including Alzheimer's, Parkinson's, glaucoma, ischemia and multiple sclerosis. Molecules such as cytokines, chemokines, reactive nitrogen/oxygen species, and proteases play an important role in promoting and/or mediating neurodegeneration. Proteases have been implicated in both physiological and pathological events, suggesting their intervention in key points when things go awry. In this review we will summarize recent findings linking extracellular proteases with neuronal cell death in both human diseases and their animal models

96. Spencer RF, Sismanis A, Kilpatrick JK, Shaia WT (2002) Demyelination of vestibular nerve axons in unilateral Meniere's disease. Ear Nose Throat J. 81:785-789
    Abstract: We conducted a study to determine whether vestibular nerves in patients with unilateral Meniere's disease whose symptoms are refractory to medical management exhibit neuropathologic changes. We also endeavored to determine whether retrocochlear abnormalities are primary or secondary factors in the disease process. To these ends, we obtained vestibular nerve segments from five patients during retrosigmoid (posterior fossa) neurectomy, immediately fixed them, and processed them for light and electron microscopy. We found that all five segments exhibited moderate to severe demyelination with axonal sparing. Moreover, we noted that reactive astrocytes produced an extensive proliferation of fibrous processes and that the Microglia assumed a phagocytic role. We conclude that the possible etiologies of demyelination include viral and/or immune-mediated factors similar to those seen in other demyelinating diseases, such as multiple sclerosis and Guillain-Barre syndrome. Our findings suggest that some forms of Meniere's disease that are refractory to traditional medical management might be the result of retrocochlear pathology that affects the neuroglial portion of the vestibular nerve

97. Stadelmann C, Kerschensteiner M, Misgeld T, Bruck W, Hohlfeld R, Lassmann H (2002) BDNF and gp145trkB in multiple sclerosis brain lesions: neuroprotective interactions between immune and neuronal cells? Brain 125:75-85
    Abstract: Recent immunohistological and imaging studies emphasize the crucial role of axonal injury in determining the extent of permanent neurological deficits in patients with multiple sclerosis. We have recently shown that human immune cells are capable of producing the neurotrophin brain-derived neurotrophic factor (BDNF), which can prevent axonal and neuronal damage after various pathological insults. BDNF imported into the CNS by immune cells would thus be an attractive candidate for mediating neuroprotective effects in multiple sclerosis. The aim of the present study was to perform a detailed immunohistochemical analysis of the expression of BDNF and its receptor truncated trkB tyrosine kinase receptor (gp145trkB) in a series of multiple sclerosis brain lesions. Our data show that various types of neurones throughout the brain are BDNF immunopositive in multiple sclerosis patients as well as in controls. Furthermore, in multiple sclerosis lesions, BDNF is primarily present in immune cells (T cells, macrophages/Microglia) and reactive astrocytes. The number of BDNF immunopositive cells correlates with lesional demyelinating activity. The BDNF receptor gp145trkB is found in neurones in the immediate vicinity of multiple sclerosis plaques as well as in reactive astrocytes within the lesion, but not in immune cells. Our results demonstrate that both BDNF and gp145trkB are expressed in multiple sclerosis lesions. This suggests that BDNF and gp145trkB are involved in immune-mediated neuroprotective interactions in multiple sclerosis, and supports the concept that immune cells produce both damaging and protective factors in multiple sclerosis lesions

98. Stangel M, Hartung HP (2002) [Intravenous immunoglobulins in multiple sclerosis. Studies and mechanisms of action--an update]. Nervenarzt 73:119-124
    Abstract: There is no doubt about the immunomodulatory capacity of intravenous immunoglobulins (IVIg). This also holds true for multiple sclerosis (MS), where clinical trials have shown a reduction in relapse rate and number of active lesions on MRI after IVIg treatment. Experimental data in the model of murine Theiler's virus encephalomyelitis (TMEV) gave rise to the hypothesis that IVIg may also promote remyelination. Unfortunately, recent trials were unable to demonstrate clinically relevant remyelination in MS patients treated with IVIg. A possible explanation could lie in the fact that IVIg do not influence the function of oligodendrogilial cells in vitro. In contrast, IVIg can protect oligodendrocytes against complement-mediated injury and thus provide more cells that could engage in remyelination. In addition, IVIg can modulate Microglial functions in vitro, thus creating a microenvironment permissive for remyelination. Should such mechanisms also be operative in vivo, they would have escaped detection in the treatment protocols used to date. It would appear that IVIg need to be administered while the inflammatory process is still ongoing, whereas the published trials included only patients with a stable deficit when there is probably little or no active inflammation. Despite new studies on IVIg, its role in the management of MS remains elusive

99. Storch MK, Weissert R, Steffer A, Birnbacher R, Wallstrom E, Dahlman I, Ostensson CG, Linington C, Olsson T, Lassmann H (2002) MHC gene related effects on Microglia and macrophages in experimental autoimmune encephalomyelitis determine the extent of axonal injury. Brain Pathol. 12:287-299
    Abstract: Myelin-oligodendrocyte-glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) in rats is a chronic inflammatory demyelinating disease of the central nervous system (CNS) strongly mimicking multiple sclerosis (MS). We determined the involvement of macrophages and Microglia in the lesions of MOG-EAE in relation to different major histocompatibility complex (MHC, RT1 in rat) haplotypes. We used intra-RT1 recombinant rat strains with recombinations between the RT1a and RT1u haplotypes on the disease permissive LEW non-MHC genome. Activated Microglia and macrophages were identified morphologically and by expression of ED1 and allograft inhibitory factor-1 (AIF-1), and differentiated by their morphological phenotype. White matter lesions contained more macrophages and less Microglia compared to grey matter lesions. Similarly active lesions were mainly infiltrated by macrophages, while Microglia were abundant in inactive demyelinated plaques. In addition, we found a highly significant genetic association between a macrophage or Microglia dominated lesional phenotype, which was independent from location and activity of the lesions. This was not only the case in demyelinating plaques of chronic EAE, but also in purely inflammatory lesions of acute passive transfer EAE. Rat strains with an u-haplotype in both the Class II and the telomeric non-classical Class I region revealed inflammatory and demyelinating lesions, which were dominated by activated Microglia. The a-haplotype in any of these regions was associated with macrophage dominated lesions. A comparison of lesions, exactly matched for stages of demyelinating activity in these different rat strains, showed that in spite of a similar extent of demyelination, axonal injury was significantly less in Microglia compared to macrophage dominated lesions. Thus, our studies document a genetic influence of the MHC-region on the relative contribution of macrophages versus Microglia in the pathogenesis of EAE

100. Ure DR, Rodriguez M (2002) Polyreactive antibodies to glatiramer acetate promote myelin repair in murine model of demyelinating disease. FASEB J. 16:1260-1262
     Abstract: Using a murine model of demyelinating disease, we demonstrate that remyelination of spinal cord axons is promoted by antibodies to glatiramer acetate (GA, Copolymer-1, Copaxone), a therapeutic agent for multiple sclerosis (MS). Glatiramer acetate is a mixture of randomly synthesized peptides that induces both T cell activation and antibody production in all treated individuals. These observations prompted us to compare the independent effects of adoptively transferred GA-reactive T cells and antibodies in mice with chronic inflammatory demyelination induced by Theiler's virus. Transferred T cells had no effect on lesion load or the extent of remyelination. Purified polyclonal GA antibodies also did not alter lesion load, which suggests that neither GA T cells or antibodies were pathogenic. On the contrary, GA antibodies enhanced the normally low level of remyelination in chronic lesions. The antibodies, which were primarily immunoglobulin (Ig) G1 and IgG2, cross-reacted with oligodendrocytes, perivascular infiltrating cells, astrocytes, and neurons in spinal cord sections. In glial cultures they bound subsets of early lineage oligodendrocytes and Microglia. Thus, several mechanisms may have contributed to the promotion of remyelination. These results support the hypothesis that the antibody response in GA-treated patients is beneficial by facilitating repair of demyelinated lesions

101. Valdo P, Stegagno C, Mazzucco S, Zuliani E, Zanusso G, Moretto G, Raine CS, Bonetti B (2002) Enhanced expression of NGF receptors in multiple sclerosis lesions. J.Neuropathol.Exp.Neurol. 61:91-98
     Abstract: The receptor for nerve growth factor (NGF) comprises a 75-kDa (NGFRp75) and a tyrosine kinase A (TrkA) subunit. In view of conflicting opinions on the identity of glial targets of NGF in human central nervous system (CNS), we examined the cellular distribution of both NGF receptor subunits in normal CNS and in chronic multiple sclerosis (MS) lesions. For this, we compared the pattern of recognition of 2 monoclonal antibodies (mAbs) and a polyclonal antiserum to NGFRp75. Only the 2 mAbs specifically recognized NGFRp75, while the polyclonal antiserum showed widespread reactivity. In normal CNS and silent MS lesions, immunohistochemistry with anti-NGFRp75 mAbs and for TrkA revealed perivascular cell reactivity. At the edge of chronic active MS lesions, selective NGFRp75 staining was prominent on reactive astrocytes, while throughout the lesion, NGFRp75 was expressed on Microglia/macrophages. The vast majority of mature or precursor oligodendrocytes did not express NGFRp75. Both NGF receptors were co-expressed on a subset of inflammatory cells. Immunoreactivity for NGFRp75 on glial and immune cells did not correlate with the distribution of apoptotic figures, as detected by TUNEL. Thus, expression of NGF receptors in active MS lesions suggests a role for NGF in regulating the autoimmune response at both immune and glial cell levels

102. Visser L, de Vos AF, Hamann J, Melief MJ, van Meurs M, van Lier RA, Laman JD, Hintzen RQ (2002) Expression of the EGF-TM7 receptor CD97 and its ligand CD55 (DAF) in multiple sclerosis. J.Neuroimmunol. 132:156-163
     Abstract: CD97 is a recently identified seven-span transmembrane (7-TM) protein that is expressed by leukocytes early after activation. CD97 binds to its cellular ligand CD55 (decay accelerating factor), which protects several cell types from complement-mediated damage. The functional consequences of CD97-CD55 binding are largely unknown, but previous data imply that CD97-CD55 interactions play a role in cellular activation, migration, and adhesion under inflammatory conditions.Here we examined the expression of CD97 and CD55 by immunohistochemistry in multiple sclerosis (MS). On the basis of established criteria for inflammation and demyelination, different lesion stages were distinguished in MS post-mortem brain tissue. In normal white matter, CD97 expression was not found, but CD55 was expressed with weak staining intensity on endothelial cells. In pre-active lesions, defined by abnormalities of the white matter, many infiltrating T cells, macrophages (MPhi) and Microglia expressed CD97. CD55 was highly expressed by endothelial cells. In active lesions with myelin degradation, MPhi and Microglia expressed both CD55 and CD97. Furthermore, a sandwich ELISA showed significantly (p<0.05) elevated levels of soluble CD97 in serum but not in cerebrospinal fluid of MS patients (37%) compared to healthy controls (8%).Collectively, these data suggest that CD97-CD55 interactions are involved in the inflammatory processes in MS. CD55, which is expressed in lesions by vessels to protect against complement-mediated damage, might bind to CD97 on infiltrating leukocytes. This interaction may facilitate cell activation and migration through the blood-brain barrier. In addition, CD97-CD55 interactions in the parenchyma of the brain may contribute to the inflammation

103. Werner K, Bitsch A, Bunkowski S, Hemmerlein B, Bruck W (2002) The relative number of macrophages/Microglia expressing macrophage colony-stimulating factor and its receptor decreases in multiple sclerosis lesions. Glia 40:121-129
     Abstract: The activation of macrophages/Microglia in multiple sclerosis (MS) lesions plays a central role in the effector phase of myelin breakdown. The precise patterns of macrophage/Microglia activation during demyelination have not yet been defined. The growth and activating factor macrophage-colony stimulating factor (M-CSF) and its specific receptor (M-CSFR) may be involved in this process. The present study investigated the expression of M-CSF and M-CSFR mRNA by in situ hybridization in 60 lesions from 32 MS patients. In the control and periplaque white matter, Microglia was almost completely M-CSFR positive. Irrespective of the demyelinating activity, an increased number of cells expressed M-CSF or M-CSFR mRNA within the lesions. However, despite the tremendous increase in macrophages/Microglia within the lesions, the relative number of these cells expressing M-CSF or M-CSFR decreased. There was no correlation of M-CSF or M-CSFR expression with active myelin breakdown. The correlation between the clinical course and the expression of M-CSF or M-CSFR mRNA revealed significant differences with the lowest expression in primary progressive MS. These results suggest a downregulation of M-CSF and M-CSFR inside the MS plaque probably due to the high amount of macrophage-derived cytokines or mediators. Nevertheless, the differences in the relative number of cells expressing the M-CSF/M-CSFR pathway implicate that this pathway may be an important contributory factor in different forms of MS pathology

104. Wesemann DR, Dong Y, O'Keefe GM, Nguyen VT, Benveniste EN (2002) Suppressor of cytokine signaling 1 inhibits cytokine induction of CD40 expression in macrophages. J.Immunol. 169:2354-2360
     Abstract: CD40 is a type I membrane-bound molecule belonging to the TNFR superfamily that is expressed on various immune cells including macrophages and Microglia. The aberrant expression of CD40 is involved in the initiation and maintenance of various human diseases including multiple sclerosis, arthritis, atherosclerosis, and Alzheimer's disease. Inhibition of CD40 signaling has been shown to provide a significant beneficial effect in a number of animal models of human diseases including the aforementioned examples. We have previously shown that IFN-gamma induces CD40 expression in macrophages and Microglia. IFN-gamma leads to STAT-1alpha activation directly and up-regulation of NF-kappaB activity due to the secretion and subsequent autocrine signaling of TNF-alpha. However, TNF-alpha alone is not capable of inducing CD40 expression in these cells. Suppressor of cytokine signaling 1 protein (SOCS-1) is a cytokine-inducible Src homology 2-containing protein that regulates cytokine receptor signaling by inhibiting STAT-1alpha activation via a specific interaction with activated Janus kinase 2. Given the important role of CD40 in inflammatory events in the CNS as well as other organ systems, it is imperative to understand the molecular mechanisms contributing to both CD40 induction and repression. We show that ectopic expression of SOCS-1 abrogates IFN-gamma-induced CD40 protein expression, mRNA levels, and promoter activity. Additionally, IFN-gamma-induced TNF-alpha secretion, as well as STAT-1alpha and NF-kappaB activation, are inhibited in the presence of SOCS-1. We conclude that SOCS-1 inhibits cytokine-induced CD40 expression by blocking IFN-gamma-mediated STAT-1alpha activation, which also then results in suppression of IFN-gamma-induced TNF-alpha secretion and subsequent NF-kappaB activation

105. Yoshikawa M, Suzumura A, Ito A, Tamaru T, Takayanagi T (2002) Effect of phosphodiesterase inhibitors on nitric oxide production by glial cells. Tohoku J.Exp.Med. 196:167-177
     Abstract: Nitric oxide (NO) is considered to play a crucial role in the development of various pathological processes in the CNS, such as neuronal degeneration, inflammation and demyelination. In order to search for the agents which suppress NO production in the CNS, we examined the effects of one of the agents which elevate cyclic AMP production, phosphodiesterase inhibitors (PDEIs), on NO production by glial cells in vitro. All the types of PDEIs, from type I- to V-specific and non-specific, suppressed the production of NO by mouse Microglia and astrocytes stimulated with lipopolysaccharide, in a dose-dependent manner. Suppression of inducible NO synthase by PDEIs was confirmed by the expression of mRNA by RT-PCR. Although it required 10 microM or higher concentration to effectively suppress NO production in vitro, certain combinations of three different PDEIs synergistically suppressed NO production by astrocytes at 1 microM which could be obtained in vivo at usual therapeutic doses. Similary, combinations of three PDEIs at 1 microM synergistically increased intracellular cAMP in astrocytes. The suppressive effects of PDEIs on NO production were abolished by addition of tumor necrosis factor alpha (TNFalpha). Thus, the main suppression mechanism of NO might be indirect through suppression of TNFalpha. Since some PDEIs are reported to pass through the blood-brain-barrier, the combination of three PDEIs may be worth trying in neurological diseases, such as multiple sclerosis, human immunodeficiency virus-related neurological diseases and other neurodegenerative disorders in which NO may play a crucial role

106. Youssef S, Stuve O, Patarroyo JC, Ruiz PJ, Radosevich JL, Hur EM, Bravo M, Mitchell DJ, Sobel RA, Steinman L, Zamvil SS (2002) The HMG-CoA reductase inhibitor, atorvastatin, promotes a Th2 bias and reverses paralysis in central nervous system autoimmune disease. Nature 420:78-84
     Abstract: Statins, 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, which are approved for cholesterol reduction, may also be beneficial in the treatment of inflammatory diseases. Atorvastatin (Lipitor) was tested in chronic and relapsing experimental autoimmune encephalomyelitis, a CD4(+) Th1-mediated central nervous system (CNS) demyelinating disease model of multiple sclerosis. Here we show that oral atorvastatin prevented or reversed chronic and relapsing paralysis. Atorvastatin induced STAT6 phosphorylation and secretion of Th2 cytokines (interleukin (IL)-4, IL-5 and IL-10) and transforming growth factor (TGF)-beta. Conversely, STAT4 phosphorylation was inhibited and secretion of Th1 cytokines (IL-2, IL-12, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha) was suppressed. Atorvastatin promoted differentiation of Th0 cells into Th2 cells. In adoptive transfer, these Th2 cells protected recipient mice from EAE induction. Atorvastatin reduced CNS infiltration and major histocompatibility complex (MHC) class II expression. Treatment of Microglia inhibited IFN-gamma-inducible transcription at multiple MHC class II transactivator (CIITA) promoters and suppressed class II upregulation. Atorvastatin suppressed IFN-gamma-inducible expression of CD40, CD80 and CD86 co-stimulatory molecules. l-Mevalonate, the product of HMG-CoA reductase, reversed atorvastatin's effects on antigen-presenting cells (APC) and T cells. Atorvastatin treatment of either APC or T cells suppressed antigen-specific T-cell activation. Thus, atorvastatin has pleiotropic immunomodulatory effects involving both APC and T-cell compartments. Statins may be beneficial for multiple sclerosis and other Th1-mediated autoimmune diseases

107. Zaheer A, Mathur SN, Lim R (2002) Overexpression of glia maturation factor in astrocytes leads to immune activation of Microglia through secretion of granulocyte-macrophage-colony stimulating factor. Biochem.Biophys.Res.Commun. 294:238-244
     Abstract: We infected a mixed culture of primary rat astrocytes and Microglia with a replication-defective adenovirus carrying the rat glia maturation factor (GMF) cDNA. Affymetrix microarray analysis showed a big increase in the expression of several major histocompatibility complex (MHC) class II proteins along with interleukin-1beta (IL-1beta). Subsequent study using reverse transcription-polymerase chain reaction (RT-PCR) yielded the same results with the mixed culture, but not with pure astrocytes or pure Microglia. We also noticed that the GMF/virus construct infected only astrocytes but not Microglia. This led us to suspect that overexpression of GMF in astrocytes resulted in the secretion of an active substance that stimulated the Microglia to express MHC II and IL-1beta. We identified this substance as granulocyte-macrophage-colony stimulating factor (GM-CSF). MHC II are unique to antigen-presenting cells such as Microglia and monocytes. The results suggest that GMF in astrocytes can initiate a series of events, leading to immune activation in the nervous system, and implicates its involvement in autoimmune diseases such as multiple sclerosis

108. Zekki H, Feinstein DL, Rivest S (2002) The clinical course of experimental autoimmune encephalomyelitis is associated with a profound and sustained transcriptional activation of the genes encoding toll-like receptor 2 and CD14 in the mouse CNS. Brain Pathol. 12:308-319
     Abstract: Experimental autoimmune encephalomyelitis (EAE) is an autoimmune demyelinating disease commonly used to model the pathogenetic mechanisms involved in multiple sclerosis (MS). In this study, we examined the effects of immunization with the myelin oligodendrocyte glycoprotein MOG(35-55) on the expression of molecules of the innate immune system, namely toll-like receptor 2 (TLR2) and CD14. Expression of the mRNA encoding TLR2 increased in the choroid plexus, the leptomeninges and within few isolated cells in the CNS parenchyma 4 to 8 days after immunization with MOG. At day 10, the signal spread across the meninges, few perivascular regions and over isolated groups of parenchymal cells. Three weeks after the MOG treatment, at which time animals showed severe clinical symptoms, a robust expression of both TLR2 and CD14 transcripts occurred in barrier-associated structures, as well as parenchymal elements of the spinal cord, and within numerous regions of the brain including, the medulla, cerebellum and the cortex. Dual labeling provided the anatomical evidence that Microglia/macrophages were positive for TLR2 in the brain of EAE mice. The regions that exhibited chronic expression of TLR2 and CD14 were also associated with an increase in NF-kappaB activity and transcriptional activation of genes encoding numerous proinflammatory molecules. The present data provide evidence that receptors of the pathogen-associated molecular patterns are strongly induced in the CNS of EAE mice, further reinforcing the concept that the innate immune system plays a determinant role in this autoimmune demyelinating disease

109. Zhang B, Yang L, Konishi Y, Maeda N, Sakanaka M, Tanaka J (2002) Suppressive effects of phosphodiesterase type IV inhibitors on rat cultured Microglial cells: comparison with other types of cAMP-elevating agents. Neuropharmacology 42:262-269
     Abstract: We investigated the effects of inhibitors of cAMP-specific phosphodiesterase type IV (PDE IV) on cultured rat Microglial cells. Microglial cells expressed mRNA encoding PDE IV. Rolipram and RO-20-1724, specific inhibitors of PDE IV, elevated the intracellular cAMP level much higher than the other types of PDE inhibitors. cAMP in astrocytes but not in cerebrocortical neurons was similarly increased in response to treatment with PDE IV inhibitors examined. The PDE IV inhibitors, a beta-adrenergic agonist isoproterenol and an adenylyl cyclase stimulant forskolin suppressed the proliferation of Microglial cells as revealed by PCNA-immunocytochemical staining. The PDE IV inhibitors suppressed release of TNF alpha and nitric oxide (NO) from lipopolysaccharide-activated Microglial cells in pure culture, while they did not affect NO release from Microglial cells in neuron-Microglia coculture. The PDE IV inhibitors also suppressed superoxide anion production by phorbol ester-treated Microglial cells. Isoproterenol and forskolin similarly suppressed the macrophage-like functions of activated Microglial cells. However, the PDE IV inhibitors displayed novel effects distinct from those of isoproterenol, forskolin and 8Br-cAMP, regarding expression of mRNAs encoding PDE IV, metallothionein-1 and hemeoxigenase-1. The present data showed that the PDE IV inhibitors can be available to control Microglial function and that their effects on glial cells should be taken into account when PDE IV inhibitors are used for treatment of brain diseases, such as multiple sclerosis

110. Allen IV, McQuaid S, Mirakhur M, Nevin G (2001) Pathological abnormalities in the normal-appearing white matter in multiple sclerosis. Neurol.Sci. 22:141-144
     Abstract: In established cases of multiple sclerosis (MS), the normal-appearing white matter (NAWM), as defined for magnetic resonance imaging (MRI), is abnormal in the majority of cases. The clinical significance of these NAWM abnormalities is the subject of debate, but there is strong correlation with degree and progression of disability. New lesions form in NAWM before blood-brain barrier breakdown, as evidenced by gadolinium enhancement. The pathological basis of these neuroimaging abnormalities is largely unknown. Definitive pathological studies on the NAWM are few and are often based on small numbers of samples and of cases. Despite a variety of MS NAWM pathological studies, major research questions, of importance to our understanding of basic pathogenetic mechanisms and consequent rational therapies, remain unanswered. These relate to the frequency and extent of oligodendrocyte/myelin and axonal abnormalities in MS NAWM, and to the cellular basis of very early MS lesions detected by neuroimaging. In a pilot study of MS NAWM, Microglial activation was demonstrated in 9 of 10 MS cases. We are currently testing the hypothesis that Microglial activation, as defined by altered phenotype and HLA-DR positivity, will act as a marker for oligodendrocyte/myelin and axonal pathology in MS NAWM

111. Bajetto A, Bonavia R, Barbero S, Florio T, Schettini G (2001) Chemokines and their receptors in the central nervous system. Front Neuroendocrinol. 22:147-184
     Abstract: Chemokines are a family of proteins associated with the trafficking of leukocytes in physiological immune surveillance and inflammatory cell recruitment in host defence. They are classified into four classes based on the positions of key cystiene residues: C, CC, CXC, and CX3C. Chemokines act through both specific and shared receptors that all belong to the superfamily of G-protein-coupled receptors. Besides their well-established role in the immune system, several recent reports have demonstrated that these proteins also play a role in the central nervous system (CNS). In the CNS, chemokines are constitutively expressed by Microglial cells, astrocytes, and neurons, and their expression can be increased after induction with inflammatory mediators. Constitutive expression of chemokines and chemokine receptors has been observed in both developing and adult brains, and the role played by these proteins in the normal brain is the object of intense study by many research groups. Chemokines are involved in brain development and in the maintenance of normal brain homeostasis; these proteins play a role in the migration, differentiation, and proliferation of glial and neuronal cells. The chemokine stromal cell-derived factor 1 and its receptor, CXCR4, are essential for life during development, and this ligand-receptor pair has been shown to have a fundamental role in neuron migration during cerebellar formation. Chemokine and chemokine receptor expression can be increased by inflammatory mediators, and this has in turn been associated with several acute and chronic inflammatory conditions. In the CNS, chemokines play an essential role in neuroinflammation as mediators of leukocyte infiltration. Their overexpression has been implicated in different neurological disorders, such as multiple sclerosis, trauma, stroke, Alzheimer's disease, tumor progression, and acquired immunodeficiency syndrome-associated dementia. An emerging area of interest for chemokine action is represented by the communication between the neuroendocrine and the immune system. Chemokines have hormone-like actions, specifically regulating the key host physiopathological responses of fever and appetite. It is now evident that chemokines and their receptors represent a plurifunctional family of proteins whose actions on the CNS are not restricted to neuroinflammation. These molecules constitute crucial regulators of cellular communication in physiological and developmental processes

112. Chabot S, Charlet D, Wilson TL, Yong VW (2001) Cytokine production consequent to T cell--Microglia interaction: the PMA/IFN gamma-treated U937 cells display similarities to human Microglia. J.Neurosci.Methods 105:111-120
     Abstract: Cognate interactions between human adult Microglia and activated T lymphocytes induce the production of inflammatory cytokines. Since this interaction can occur in a non-antigen-dependent manner, it is relevant to a variety of CNS diseases where activated T cells, regardless of specificities, come into contact with Microglia; these disorders include multiple sclerosis, trauma, stroke and Alzheimer's disease. A model cell line would facilitate studies of the engagement between T cells and human adult Microglia, since the latter are difficult to obtain in substantial quantity or frequency. This study shows that the PMA/IFN gamma-treated U937 cell line shows similarities to Microglia in its interaction with activated T lymphocytes, in that the production of tumor necrosis factor (TNF)-alpha, interleukin (IL)-4, IL-10 and IL-12 is induced. Morphological features and mechanisms of cytokine production resemble those observed in Microglia--T cell co-cultures since CTLA-4 and CD40--CD40L blockades reduce TNF-alpha and IL-10 levels, while anti-CD23 inhibits IL-10 only in U937--T cell interactions. We propose that PMA/IFN gamma-treated U937 cells can serve as a model of human adult Microglia to study cytokine generation in response to interactions with activated T cells

113. Chan A, Magnus T, Gold R (2001) Phagocytosis of apoptotic inflammatory cells by Microglia and modulation by different cytokines: mechanism for removal of apoptotic cells in the inflamed nervous system. Glia 33:87-95
     Abstract: Apoptosis of autoaggressive T cells in the central nervous system (CNS) is an effective, nonphlogistic mechanism for the termination of autoimmune inflammation in experimental autoimmune encephalomyelitis (EAE). The clearance of apoptotic leukocytes by tissue-specific phagocytes is a critical event in the resolution of the inflammatory attack. To investigate the role of Microglia in the removal of apoptotic cells and potential regulatory mechanisms of Microglial phagocytosis, an in vitro phagocytosis assay was established, using Lewis rat Microglia. Microglia exhibited a high capacity for the uptake of apoptotic autologous thymocytes, as well as apoptotic encephalitogenic myelin basic protein (MBP)-specific T cells, in contrast to nonapoptotic target cells. Pretreatment of Microglia with interferon-gamma (IFN-gamma) raised the proportion of Microglia capable of phagocytosing apoptotic cells to 75% above the untreated controls. The increased phagocytic activity was selective for apoptotic target cells and was not dependent on phosphatidylserine-mediated recognition mechanisms. In contrast, preincubation of Microglia with interleukin-4 (IL-4) inhibited the uptake of apoptotic cells, whereas tumor-necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta) did not alter phagocytosis. Phagocytic clearance of apoptotic inflammatory cells by Microglia may be an important mechanism for the termination of autoimmune inflammation in the CNS. Augmentation of Microglial phagocytosis by the Th-1-type cytokine IFN-gamma suggests a feedback mechanism for the accelerated clearance of the inflammatory infiltrate in the CNS

114. Copelman CA, Diemel LT, Gveric D, Gregson NA, Cuzner ML (2001) Myelin phagocytosis and remyelination of macrophage-enriched central nervous system aggregate cultures. J.Neurosci.Res. 66:1173-1178
     Abstract: An increased level of myelin basic protein (MBP) degradation peptide 80-89, representative of myelin breakdown, is detected in myelinating foetal rat brain aggregate cultures supplemented with peritoneal macrophages at a time coinciding with the onset of myelination. During the period of myelination, the proportion of activated macrophages/Microglia in the aggregates decreases, accompanied by a reduction in the content of MBP degradation products. During the recovery period following a demyelinating episode, the rate of MBP synthesis in antibody-treated standard aggregates was greater than in their medium controls. However, the rate of MBP accumulation was not as efficient in macrophage-enriched aggregates and was associated with persistently raised MBP peptide levels. Thus, as occurs in multiple sclerosis lesions, attempts at remyelination appear to be counterbalanced by macrophage-mediated demyelination, with the continued presence of degraded myelin rendering a local environment that is not fully conducive to remyelination

115. de Goer de Herve MG, Delfraissy JF, Taoufik Y (2001) Following direct CD40 activation, human primary Microglial cells produce IL-12 p40 but not bioactive IL-12 p70. Cytokine 14:88-96
     Abstract: There is accumulating evidence that interleukin 12 (IL-12) is involved in the pathogenesis of multiple sclerosis. In the periphery, this cytokine is produced by antigen-presenting cells (APCs) following interaction with activated T cells. CD40 ligation plays a crucial role in this production. Microglial cells are thought to play a major role in antigen presentation in the central nervous system. In this work, we examined IL-12 production by human primary Microglial cells after CD40 ligation. These cells expressed CD40 and MHC class II following interferon-gamma activation. IL-12 p40 mRNA and protein, but not bioactive IL-12 p70, were detected in response to direct CD40 activation. Microglial cells co-cultured with activated allogenic CD4+ T lymphocytes also produced IL-12 p40 but not IL-12 p70. This IL-12 p40 production was inhibited by anti-CD40 ligand. Altogether, these results suggest that CD40-CD40-ligand interaction provides a signal that triggers IL-12 p40 expression. However, other interaction(s) may be required during antigen presentation for bioactive heterodimeric IL-12 p70 to be produced by Microglial cells

116. De Groot CJ, Bergers E, Kamphorst W, Ravid R, Polman CH, Barkhof F, van d, V (2001) Post-mortem MRI-guided sampling of multiple sclerosis brain lesions: increased yield of active demyelinating and (p)reactive lesions. Brain 124:1635-1645
     Abstract: Macroscopic sampling of multiple sclerosis lesions in the brain tends to find chronic lesions. For a better understanding of the dynamics of the multiple sclerosis disease process, research into new and developing lesions is of great interest. As MRI in vivo effectively demonstrates lesions in multiple sclerosis patients, we have applied it to unfixed post-mortem brain slices to identify abnormalities, in order to obtain a higher yield of active lesions. The Netherlands Brain Bank organized the rapid autopsy of 29 multiple sclerosis patients. The brain was cut in 1 cm coronal slices. One or two slices were subjected to T(1)- and T(2)-weighted MRI, and then cut at the plane of the MRI scan into 5 mm thick opposing sections. Areas of interest were identified based on the MRI findings and excised. One half was fixed in 10% formalin and paraffin-embedded, and the corresponding area in the adjacent half was snap-frozen in liquid nitrogen. In total, 136 out of 174 brain tissue samples could be matched with the abnormalities seen on T(2)-weighted MRIs. The stage of lesional development was determined (immuno) histochemically. For 54 MRI-detectable samples, it was recorded whether they were macroscopically detectable, i.e. visible and/or palpable. Histopathological analysis revealed that 48% of the hyperintense areas seen on T(2)-weighted images represented active lesions, including lesions localized in the normal appearing white matter, without apparent loss of myelin but nevertheless showing a variable degree of oedema, small clusters of Microglial cells with enhanced major histocompatibility complex class II antigen, CD45 and CD68 antigen expression and a variable number of perivascular lymphocytes around small blood vessels [designated as (p)reactive lesions]. From the macroscopically not-visible/not-palpable MRI-detected abnormalities, 58% were (p)reactive lesions and 21% contained active demyelinating lesions. In contrast, visible and/or palpable brain tissue samples mainly contained chronic inactive lesions. We conclude that MRI-guided sampling of brain tissue increases the yield of active multiple sclerosis lesions, including active demyelinating and (p)reactive lesions

117. De Groot CJ, Woodroofe MN (2001) The role of chemokines and chemokine receptors in CNS inflammation. Prog.Brain Res. 132:533-544

118. Dorries R (2001) The role of T-cell-mediated mechanisms in virus infections of the nervous system. Curr.Top.Microbiol.Immunol. 253:219-245
     Abstract: T lymphocytes play a decisive role in the course and clinical outcome of viral CNS infection. Summarizing the information presented in this review, the following sequence of events might occur during acute virus infection: After invasion of the host and a few initial rounds of replication, the virus reaches the CNS in most cases by hematogeneous spread. After passage through the BBB, CNS cells are infected and replication of virus in brain cells causes activation of the surrounding Microglia population. Moreover, local production of IFN-alpha/beta induces expression of MHC antigens on CNS cells, and Microglial cells start to phagocytose cellular debris, which accumulates as a result of virus-induced cytopathogenic effects. Upon phagocytosis, Microglia becomes more activated; they up-regulate MHC molecules, acquire antigen presentation capabilities and secrete chemokines. This will initiate up-regulation of adhesion molecules on adjacent endothelial cells of the BBB. Transmigration of activated T lymphocytes through the BBB is followed by interaction with APC, presenting the appropriate peptides in the context of MHC antigens. It appears that CD8+ T lymphocytes are amongst the first mononuclear cells to arrive at the infected tissue. Without a doubt, their induction and attraction is deeply influenced by natural killer cells, which, after virus infection, secrete IFN-gamma, a cytokine that stimulates CD8+ T cells and diverts the immune response to a TH1-type CD4+ T cell-dominated response. Following the CD8+ T lymphocytes, tissue-penetrating, TH1 CD4+ T cells contact local APC. This results in a tremendous up-regulation of MHC molecules and secretion of more chemotactic and toxic substances. Consequently an increasing number of inflammatory cells, including macrophages/Microglia and finally antibody-secreting plasma cells, are attracted to the site of virus infection. All trapped cells are mainly terminally differentiated cells that are going to enter apoptosis during or shortly after exerting their effector functions. The clinical consequences and the influence of the effector phase on the further course of the infection depends on the balance and fine-tuning of the contributing lymphoid cell populations. Generally, any delay in the recruitment of effector lymphocytes to the tissue or an unbalanced combination of lymphocyte subsets allows the virus to spread in the CNS, which in turn will cause severe immune-mediated tissue effects as well as disease. If either too late or partially deficient, the immune system response may contribute to a lethal outcome or cause autosensitization to brain-specific antigens by epitope spreading to the antigen-presenting system in peripheral lymphoid tissue. This could form the basis for subsequent booster reactions of autosensitized CD4+ T cells--a process that finally will end in an inflammatory autoimmune reaction, which in humans we call multiple sclerosis. In contrast, a rapid and specific local response in the brain tissue will result in efficient limitation of viral spread and thereby a subclinical immune system-mediated termination of the infection. After clearance of virus-infected cells, downsizing of the local response probably occurs via self-elimination of the contributing T cell populations and/or by so far unidentified signal pathways. However, much of this is highly speculative, and more data have to be collected to make decisive conclusions regarding this matter. Several strategies have been developed by viruses to escape T cell-mediated eradication, including interference with the MHC class I presentation pathway of the host cell or "hiding" in cells which lack MHC class I expression. This may result in life-long persistence of the virus in the brain, a state which probably is actively controlled by T lymphocytes. Under severe immunosuppression, however, reactivation of viral replication can occur, which is a lethal threat to the host

119. Drew PD, Chavis JA (2001) The cyclopentone prostaglandin 15-deoxy-Delta(12,14) prostaglandin J2 represses nitric oxide, TNF-alpha, and IL-12 production by Microglial cells. J.Neuroimmunol. 115:28-35
     Abstract: Prostaglandins are generally considered pro-inflammatory molecules that contribute to the pathology associated with a variety of immune-mediated diseases including multiple sclerosis. However, recently it has been demonstrated that specific cyclopentone prostaglandin metabolites including 15-deoxy-Delta(12,14) prostaglandin J2 (15d-PGJ2) are capable of repressing the production of pro-inflammatory molecules by cells of the monocyte/macrophage lineage. Activated Microglia produce nitric oxide (NO) and TNF-alpha, molecules which can be toxic to cells including oligodendrocytes, thus potentially contributing to the pathology associated with multiple sclerosis. The current study demonstrates that 15d-PGJ2 inhibits lipopolysachharide (LPS) induction of NO and TNF-alpha production by rat primary Microglia and mouse N9 Microglial cells. 15d-PGJ2 also inhibits NO production by Microglial cells activated in response to IFN-gamma and TNF-alpha, cytokines believed to be important modulators of multiple sclerosis. IL-12 plays a critical role in stimulating the production of Th1 cells, which are believed to contribute to the pathology associated with multiple sclerosis. The current studies demonstrate that 15d-PGJ2 represses the production of IL-12 by Microglial cells. Collectively, these studies demonstrate that the prostaglandin metabolite 15d-PGJ2 represses Microglial production of potentially cytotoxic molecules, as well as molecules capable of altering T-cell phenotype. These in vitro studies suggest the possibility that the prostaglandin 15d-PGJ2 may modulate inflammatory diseases including multiple sclerosis

120. Espejo C, Carrasco J, Hidalgo J, Penkowa M, Garcia A, Saez-Torres I, Martinez-Caceres EM (2001) Differential expression of metallothioneins in the CNS of mice with experimental autoimmune encephalomyelitis. Neuroscience 105:1055-1065
     Abstract: multiple sclerosis is an inflammatory, demyelinating disease of the CNS. Metallothioneins-I+II are antioxidant proteins induced in the CNS by immobilisation stress, trauma or degenerative diseases which have been postulated to play a neuroprotective role, while the CNS isoform metallothionein-III has been related to Alzheimer's disease. We have analysed metallothioneins-I-III expression in the CNS of mice with experimental autoimmune encephalomyelitis. Moreover, we have examined the putative role of interferon-gamma, a pro-inflammatory cytokine, in the control of metallothioneins expression during experimental autoimmune encephalomyelitis in interferon-gamma receptor knockout mice with two different genetic backgrounds: 129/Sv and C57BL/6x129/Sv.Mice with experimental autoimmune encephalomyelitis showed a significant induction of metallothioneins-I+II in the spinal cord white matter, and to a lower extent in the brain. Interferon-gamma receptor knockout mice suffered from a more severe experimental autoimmune encephalomyelitis, and interestingly showed a higher metallothioneins-I+II induction in both white and grey matter of the spinal cord and in the brain. In contrast to the metallothioneins-I+II isoforms, metallothionein-III expression remained essentially unaltered during experimental autoimmune encephalomyelitis; interferon-gamma receptor knockout mice showed an altered metallothionein-III expression (a slight increase in the spinal cord white matter) only in the C57BL/6x129/Sv background. Metallothioneins-I+II proteins were prominent in areas of induced cellular infiltrates. Reactive astrocytes and activated monocytes/macrophages were the sources of metallothioneins-I+II proteins.From these results we suggest that metallothioneins-I+II but not metallothionein-III may play an important role during experimental autoimmune encephalomyelitis, and indicate that the pro-inflammatory cytokine interferon-gamma is unlikely an important factor in this response

121. Flugel A, Bradl M, Kreutzberg GW, Graeber MB (2001) Transformation of donor-derived bone marrow precursors into host Microglia during autoimmune CNS inflammation and during the retrograde response to axotomy. J.Neurosci.Res. 66:74-82
     Abstract: Macrophages in the brain can have a triple source. They may originate from recently blood-derived precursors, from the largely resident perivascular cell population (perivascular macrophages and related cells), and from intrinsic parenchymal as well as perivascular Microglia. Although continuous exchange of part of the perivascular cell population with bone marrow-derived precursors is now accepted, the turnover of adult parenchymal Microglia has remained enigmatic. Using bone-marrow chimeras carrying an unexpressed marker gene and carbon labeling of peripheral monocyte/macrophages in a combined model of facial nerve axotomy and transfer experimental autoimmune encephalitis, we demonstrate for the first time that there is an easy to induce exchange between parenchymal central nervous system (CNS) Microglia and the macrophage precursor cell pool of the bone marrow. Furthermore, very low level infiltration of the CNS parenchyma by recently bone marrow-derived Microglia could be observed after simple peripheral nerve axotomy that is followed by neuronal regeneration. Thus, Microglial cells can be considered wanderers between the peripheral immune system and the CNS where they may act as a "Trojan horse" in infections. The fact that recently bone marrow-derived parenchymal Microglia fully integrate into a regenerating brain nucleus' architecture encourages entirely new approaches for delivering genes into the adult CNS

122. Furlan R, Poliani PL, Marconi PC, Bergami A, Ruffini F, Adorini L, Glorioso JC, Comi G, Martino G (2001) Central nervous system gene therapy with interleukin-4 inhibits progression of ongoing relapsing-remitting autoimmune encephalomyelitis in Biozzi AB/H mice. Gene Ther. 8:13-19
     Abstract: multiple sclerosis (MS) is an immune-mediated inflammatory disease of the central nervous system (CNS) that might benefit from anti-inflammatory therapies. However, systemic delivery of anti-inflammatory drugs in MS patients has so far been disappointing, mostly due to the limited capacity of these molecules to enter the CNS. We injected into the cisterna magna (i.c.) of Biozzi AB/H mice affected by a relapsing-remitting form of experimental autoimmune encephalomyelitis (EAE), the animal model of MS, a non-replicative herpes simplex virus (HSV) type-1-derived vector containing the interleukin (IL)-4 gene (d120:LacZ:IL-4). CNS delivery of the d120:LacZ:IL-4 vector, after EAE onset, induced the in situ production of IL-4 by CNS-resident cells facing the cerebrospinal fluid (CSF) spaces and reduced by 47% (P < 0.02) the disease-related deaths. Compared with mice treated with the control d120:lacZ vector, IL-4-treated mice also showed a shorter duration of the first EAE attack, a longer inter-relapse period, and a reduction in the severity and duration of the first relapse. Protection from EAE progression in IL-4-treated mice was associated with activation of Microglia in spinal cord areas where mRNA content of the pro-inflammatory chemokines, macrophage chemoattractant protein-1 (MCP-1) and Rantes, was reduced and that of the anti-inflammatory cytokine IL-4 was increased. Finally, CNS-infiltrating mononuclear cells from IL-4-treated mice produced lower levels of MCP-1 mRNA compared with control mice. Our results, showing that IL-4 gene delivery using HSV-1 vectors induces protection from EAE by in situ modulating the cytokine/chemokine-mediated circuits sustaining effector cell functions, indicate that the intrathecal 'therapeutic' use of nonreplicative HSV-1-derived vectors containing anti-inflammatory molecules might represent an alternative strategy in inflammatory diseases of the CNS

123. Gebicke-Haerter PJ, Spleiss O, Ren LQ, Li H, Dichmann S, Norgauer J, Boddeke HW (2001) Microglial chemokines and chemokine receptors. Prog.Brain Res. 132:525-532

124. Gebicke-Haerter PJ (2001) Microglia in neurodegeneration: molecular aspects. Microsc.Res.Tech. 54:47-58
     Abstract: Inflammatory events in the CNS are associated with injuries as well as with well-known chronic degenerative diseases, such as multiple sclerosis, Parkinson's, or Alzheimer's disease. Compared to inflammation in peripheral tissues, inflammation in brain appears to follow distinct pathways and time-courses, which likely has to do with a relatively strong immunosuppression in that organ. For this reason, it is of great importance to get insights into the molecular mechanism governing immune reactions in brain tissue. This task is hard to achieve in vivo, but can be approached by studying the major cell type responsible for brain inflammation, the Microglia, in culture. Since these cells are the only professional antigen-presenting cells resident in brain parenchyma, molecular mechanisms of antigen presentation are being discussed first. After covering the expression and regulation of anti- and proinflammatory cytokines, induction and regulation of two key enzymes and their products-COX-2 and iNOS-are summarized. Possibly, pivotal molecular targets for drug therapies of brain disorders will be discovered in intracellular signaling pathways leading to activation of transcription factors. Finally, the impact of growth factors, of neurotrophins in particular, is highlighted. It is concluded that the presently available data on the molecular level is far from being statisfying, but that only from better insights into molecular events will we obtain the information required for more specific therapies

125. Giralt M, Carrasco J, Penkowa M, Morcillo MA, Santamaria J, Campbell IL, Hidalgo J (2001) Astrocyte-targeted expression of interleukin-3 and interferon-alpha causes region-specific changes in metallothionein expression in the brain. Exp.Neurol. 168:334-346
     Abstract: Transgenic mice expressing IL-3 and IFN-alpha under the regulatory control of the GFAP gene promoter (GFAP-IL3 and GFAP-IFNalpha mice) exhibit a cytokine-specific, late-onset chronic-progressive neurological disorder which resemble many of the features of human diseases such as multiple sclerosis, Aicardi-Goutieres syndrome, and some viral encephalopathies including HIV leukoencephalopathy. In this report we show that the metallothionein-I+II (MT-I+II) isoforms were upregulated in the brain of both GFAP-IL3 and GFAP-IFNalpha mice in accordance with the site and amount of expression of the cytokines. In the GFAP-IL3 mice, in situ hybridization analysis for MT-I RNA and radioimmunoassay results for MT-I+II protein revealed that a significant upregulation was observed in the cerebellum and medulla plus pons at the two ages studied, 1-3 and 6-10 months. Increased MT-I RNA levels occurred in the Purkinje and granular layers of the cerebellum, as well as in its white matter tracts. In contrast to the cerebellum and brain stem, MT-I+II were downregulated by IL-3 in the hippocampus and the remaining brain in the older mice. In situ hybridization for MT-III RNA revealed a modest increase in the cerebellum, which was confirmed by immunohistochemistry. MT-III immunoreactivity was present in cells that were mainly round or amoeboid monocytes/macrophages and in astrocytes. MT-I+II induction was more generalized in the GFAP-IFNalpha (GIFN12 and GIFN39 lines) mice, with significant increases in the cerebellum, thalamus, hippocampus, and cortex. In the high expressor line GIFN39, MT-III RNA levels were significantly increased in the cerebellum (Purkinje, granular, and molecular layers), thalamus, and hippocampus (CA2/CA3 and especially lacunosum molecular layers). Reactive astrocytes, activated rod-like Microglia, and macrophages, but not the perivenular infiltrating cells, were identified as the cellular sources of the MT-I+II and MT-III proteins. The pattern of expression of the different MT isoforms in these transgenic mice differed substantially, demonstrating unique effects associated with the expression of each cytokine. The results indicate that the MT expression in the CNS is significantly affected by the cytokine-induced inflammatory response and support a major role of these proteins during CNS injury

126. Gobin SJ, Montagne L, Van Zutphen M, van d, V, van den Elsen PJ, De Groot CJ (2001) Upregulation of transcription factors controlling MHC expression in multiple sclerosis lesions. Glia 36:68-77
     Abstract: The expression of major histocompatibility complex (MHC) class I and class II in the CNS has received considerable interest because of its importance in neurodegenerative or inflammatory diseases, such as multiple sclerosis (MS). However, at the moment nothing is known about the expression patterns of transcription factors controlling MHC expression in MS lesions. Here, we performed an extensive immunohistochemical analysis on MS affected postmortem brain tissue to determine the cellular localization and distribution of different MHC-controlling transcription factors. We show that phagocytic macrophages in active demyelinating MS lesions displayed a moderate to strong immunostaining of the MHC-specific transcription factors RFX and CIITA, as well as the general transcription factors NF-kappaB, IRF1, STAT1, USF, and CREB, which was congruent with a strongly enhanced expression of HLA-DR, HLA-DQ, HLA-DP, and HLA class I. In the normal-appearing white matter (NAWM), clusters of activated Microglial cells forming preactive lesions displayed an overall stronger expression level of these transcription factors, combined with a strong to intense level of MHC class I and class II immunostaining. In general, astrocytes and oligodendrocytes either did not express, or weakly expressed, these transcription factors, correlating with a lack of MHC class II and weak MHC class I expression. Together, the elevated expression level of transcription factors governing expression of MHC class I and class II molecules in activated Microglial cells and phagocytic macrophages strongly suggests a general state of Microglial cell activation in MS lesions

127. Imrich H, Harzer K (2001) On the role of peripheral macrophages during active experimental allergic encephalomyelitis (EAE). J.Neural Transm. 108:379-395
     Abstract: Experimental allergic encephalitis (EAE) is an experimental autoimmune inflammatory condition of the central nervous system (CNS) that serves as a disease model for multiple sclerosis (MS). The primary effector mechanisms of the immune system leading to tissue destruction during EAE remain still controversial. T-cells, Microglia, and macrophages infiltrating the brain parenchyma are suggested to be involved. To clarify the role of these cells during disease Lewis rats were immunised with different immunisation protocols: Immunisation with myelin basic protein (MBP) in complete Freunds adjuvant (CFA) containing high dose of mycobacterial components induced severe disease, whereas immunisation with low dose of mycobacterial components induced only mild disease. Severely and mildly diseased animals were analysed with respect to infiltration of T-cells, macrophages and upregulation of MHC class II molecules on Microglia in the brain. All immunised rats showed high T-cell infiltration accompanied by Microglia activation. The degree of disease and the infiltration of macrophages varied with dose of adjuvant. Lowering the dose of adjuvant prevented the development of disease but also the influx of peripheral macrophages into the brain without affecting the peripheral T-cell response to the autoantigen. Thus, appearance of (autoreactive) T-cells in the brain and Microglia activation were probably not sufficient for development of disease. It can be concluded that peripheral macrophages play an essential or even key role in the pathogenesis of active EAE

128. Langford D, Masliah E (2001) Crosstalk between components of the blood brain barrier and cells of the CNS in Microglial activation in AIDS. Brain Pathol. 11:306-312
     Abstract: During the progression of AIDS, a majority of patients develop cognitive disorders such as HIV encephalitis (HIVE) and AIDS dementia complex (ADC), which correlate closely with macrophage infiltration into the brain and Microglial activation. Microglial activation occurs in response to infection, inflammation and neurological disorders including HIVE, Alzheimer's disease, Parkinson's disease and multiple sclerosis. Microglia can be activated by immunoreactive cells independent of, but enhanced by HIV infection, from at least two routes. Activation may occur from signals originating from activated monocytes and lymphocytes in the blood stream, which initiate a cascade of stimuli that ultimately reach Microglia in the brain or from activated macrophages/Microglia/astrocytes within the brain. Effects of Microglial activation stemming from both systemic and CNS HIV infection act together to commence signaling feedback, leading to HIVE and increased neurodegeneration. Most recent data indicate that in AIDS patients, Microglial activation in the brain with subsequent release of excitotoxins, cytokines and chemokines leads to neurodegeneration and cognitive impairment. Since the presence of HIV in the brain results from migration of infected monocytes and lymphocytes across the vascular boundary, the development of novel therapies aimed at protecting the integrity of the blood brain barrier (BBB) upon systemic HIV infection is critical for controlling CNS infection

129. Magnus T, Chan A, Grauer O, Toyka KV, Gold R (2001) Microglial phagocytosis of apoptotic inflammatory T cells leads to down-regulation of Microglial immune activation. J.Immunol. 167:5004-5010
     Abstract: Apoptotic cell death is an established mechanism to terminate an inflammatory response in rodent or human brains. Microglia, as the resident phagocyte, is a strong candidate for the clearance of apoptotic lymphocytes. Apoptosis was induced in cultured autologous thymocytes and in myelin basic protein (MBP)-specific, encephalitogenic T cells from Lewis rats by the addition of 0.1 microg/ml methylprednisolone. The amount of phagocytosis of apoptotic cells was assessed using an in vitro phagocytosis assay. Supernatants were collected to measure Microglial cytokine secretion. The state of immune activation in Microglia was investigated by a T cell proliferation assay and by flow cytometric analysis of Microglial surface expression of immune molecules. Microglia ingested specifically apoptotic cells (apoptotic thymocytes as well as MBP-specific T cells) in contrast to nonapoptotic control cells (p < 0.0001). Subsequent secretion of the proinflammatory cytokines TNF-alpha and IL-12 was significantly decreased, while the secretion of IL-10 and TGF-beta was not affected. Furthermore, ingestion of apoptotic cells led to increased Microglial MHC class II expression without concomitant increase in MHC class I, costimulatory molecules, and ICAM expression. The Ag-specific activation of MBP-specific T cells in cocultures with Microglia that had ingested apoptotic cells was significantly less than that of identical T cells that interacted with nonphagocytosing Microglia. Together with negative results obtained in a trans-well system, this is in support of a cell contact-mediated effect. Microglia might play an important role in the clearance of apoptotic cells. The uptake of apoptotic cells by Microglia is tolerogenic and results in a reduced proinflammatory cytokine production and a reduced activation of encephalitogenic T cells. This might help to restrict an autoimmune inflammation and minimize damage in the inflamed brain

130. Mason JL, Suzuki K, Chaplin DD, Matsushima GK (2001) Interleukin-1beta promotes repair of the CNS. J.Neurosci. 21:7046-7052
     Abstract: Interleukin-1beta (IL-1beta) is a proinflammatory cytokine associated with the pathophysiology of demyelinating disorders such as multiple sclerosis and viral infections of the CNS. However, we demonstrate here that IL-1beta appears to promote remyelination in the adult CNS. In IL-1beta(-/-) mice, acute demyelination progressed similarly to wild-type mice and showed parallel mature oligodendrocyte depletion, Microglia-macrophage accumulation, and the appearance of oligodendrocyte precursors. In contrast, IL-1beta(-/-) mice failed to remyelinate properly, and this appeared to correlate with a lack of insulin-like growth factor-1 (IGF-1) production by Microglia-macrophages and astrocytes and to a profound delay of precursors to differentiate into mature oligodendrocytes. Thus, IL-1beta may be crucial to the repair of the CNS, presumably through the induction of astrocyte and Microglia-macrophage-derived IGF-1

131. Minagar A, Shapshak P, Heyes M, Sheremata WA, Fujimara R, Ownby R, Goodkin K, Eisdorfer K (2001) Microglia and astrocytes in neuro-AIDS, alzheimers disease, and multiple sclerosis. ScientificWorldJournal. 1:69
     Abstract: The central nervous system (CNS) has traditionally been regarded as an immunologically privileged and isolated organ. This immunoisolation is achieved through the specific structure of the blood brain barrier and CNS immunosuppressive microenvironment. 1,2 However, activated macrophage/Microglia (MO) and astrocytes participate in the pathogenesis of various neurological diseases through expressing of MHC and adhesion molecules and releasing reactive oxygen intermediates, quinolinic acid, chemokines, cytokines, and other components of inflammation. The role of macroglia/macrophages and astrocytes in cellular/molecular mechanisms of pathogenesis of three common dementias; HIV-associated dementia (HAD), Alzheimer's disease (AD), and multiple sclerosis (MS) have been studied. Each disease had its specific clinical course and symptomatology that are well known. At the cellular and molecular levels there are both common and distinct features that are under study and require further elucidation. Recently Link et al. 3 indicated support for roles of both Microglia and astrocytes in regulating demyelination in MS. We have generalized this significant concept of neuropathogenesis to HAD and AD. HIV-1 infection is the original insult in Neuro-AIDS. In fact, our results indicate that there are neurovirulent strains of HIV-1 that invade the brain. Furthermore, we have published preliminary studies showing that there is brain regional heterogeneity of macrophage/Microglia, virus load, and virus strains. At the cellular level, there is a greater virus load in central nervous system (CNS) macrophage/Microglia than in peripheral nervous system (PNS) macrophages. In both tissues, macrophages appear to be involved in pathogenesis and produce toxic molecules including cytokines, chemokines, and nitric oxide (NO). Furthermore, we have demonstrated increased NO synthase in brain interneurons of drug abusers with AIDS associated with increased neuronal death (manuscript under review). The etiologies of AD and MS remain unknown. However, cellular/molecular mechanisms of pathogenesis are specific manifestations of these diseases. For example, it is clear that AD results from production of aberrant eta-amyloid proteins and oligopeptides. Microglia and astrocytes are activated as a result and are associated with further damage. Demyelination in MS involves lipid-laden macrophages perhaps spurred by viral and other antigens. In all three diseases cytokine/chemokine communication between Microglia and astrocytes occur and apoptosis is a mechanism of neuronal death. Also, apoptosis of oligodendrocytes occurs in MS. <?Pub _font AllCap="yes"?

132. Minami M (2001) [Cytokines and chemokines: mediators for intercellular communication in the brain]. Yakugaku Zasshi 121:875-885
     Abstract: The brain includes glial cells (astrocytes, Microglia and oligodendrocytes) and endothelial cells in addition to neurons. Under some pathological conditions, it is invaded by leukocytes such as neutrophils, monocytes/macrophages and lymphocytes. Intercellular communication across these cell species is supposed to play crucial roles both in the brain functions and dysfunctions. However, the molecular basis of such intercellular communication remains unclear. We have studied the roles of cytokines and chemokines, which have been investigated as essential mediators in the immune and inflammatory systems, in intercellular communication across neurons, glial cells, endothelial cells and leukocytes. Messenger RNA expression of cytokines such as interleukin-1 beta was induced in brain Microglia by i.p. injection of excitotoxin and neurostimulant, at least, partly via catecholaminergic systems. Messenger RNA of other cytokines such as leukemia inhibitory factor was induced in astrocytes. This cytokine specifically induced nociceptin mRNA in the cultured cortical neurons. Constitutive expression of some chemokines such as fractalkine and stromal cell derived factor-1 alpha was observed in the brain, suggesting that they play important roles in maintenance of brain homeostasis or determination of the patterning of neurons and/or glial cells in the developing and adult brains. Cytokines such as interleukin-1 beta and chemokines such as monocyte chemoattractant protein-1 and macrophage inflammatory protein-1 alpha were produced in ischemic brain and implicated in ischemic brain injury. In addition to ischemia, cytokines, chemokines and their receptors have been shown to be involved in various neurodegenerative diseases such as multiple sclerosis, Alzheimer's disease and AIDS dementia syndrome. They are potential targets for therapeutic intervention for neurodegenerative diseases

133. Morse RH, Seguin R, McCrea EL, Antel JP (2001) NK cell-mediated lysis of autologous human oligodendrocytes. J.Neuroimmunol. 116:107-115
     Abstract: Although considered an autoimmune disease, the mechanisms underlying oligodendrocyte (OL)/myelin injury in multiple sclerosis (MS) remain to be established. We utilized in vitro assays to demonstrate that human OLs, as well as other glial elements (astrocytes, Microglia), were susceptible to injury mediated by peripheral blood-derived mononuclear cell preparations (MNCs) enriched for natural killer (NK cells) by depleting CD3(+) +/- CD19(+) cells through use of either magnetic beads or cell sorting. Cytotoxic effects of the NK cell-enriched effectors were dependent on pre-exposure of these cells to IL-2. Furthermore, we found that autologous OLs were as susceptible to injury mediated by IL-2 activated NK cells as were heterologous OLs. In context of the tissue injury that occurs in MS, our results suggest that the inflammatory milieu in MS lesions could provide conditions required for NK cell activation and that such effector cells can bypass the putative protective effects of self-MHC class I molecules that may be expressed on OLs

134. Neumann H (2001) Control of glial immune function by neurons. Glia 36:191-199
     Abstract: The immune status of the central nervous system (CNS) is strictly regulated. In the healthy brain, immune responses are kept to a minimum. In contrast, in a variety of inflammatory and neurodegenerative diseases, including multiple sclerosis, infections, trauma, stroke, neoplasia, and Alzheimer's disease, glial cells such as Microglia gain antigen-presenting capacity through the expression of major histocompatibility complex (MHC) molecules. Further, proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF), interleukin-1beta (IL-1beta), and interferon-gamma (IFN-gamma), as well as chemokines, are synthesized by resident brain cells and T lymphocytes invade the affected brain tissue. The proinflammatory cytokines stimulate Microglial MHC expression in the lesioned CNS areas only. However, the induction of brain immunity is strongly counterregulated in intact CNS areas. For instance, recent work demonstrated that Microglia are kept in a quiescent state in the intact CNS by local interactions between the Microglia receptor CD200 and its ligand, which is expressed on neurons. Work done in our laboratory showed that neurons suppressed MHC expression in surrounding glial cells, in particular Microglia and astrocytes. This control of MHC expression by neurons was dependent on their electrical activity. In brain tissue with intact neurons, the MHC class II inducibility of Microglia and astrocytes by the proinflammatory cytokine IFN-gamma was reduced. Paralysis of neuronal electric activity by neurotoxins restored the induction of MHC molecules on Microglia and astrocytes. Loss of neurons or their physiological activity would render the impaired CNS areas recognizable by invading T lymphocytes. Thus, immunity in the CNS is inhibited by the local microenvironment, in particular by physiologically active neurons, to prevent unwanted immune mediated damage of neurons

135. Nguyen D, Stangel M (2001) Expression of the chemokine receptors CXCR1 and CXCR2 in rat oligodendroglial cells. Brain Res.Dev.Brain Res. 128:77-81
     Abstract: Chemokines are small proteins that act as chemoattractants and activators in leukocytes during physiological and inflammatory processes. In the CNS chemokine receptors have been shown to be expressed on neurons, astrocytes and Microglia but their function in the CNS is poorly understood. CXCR1 and CXCR2 are receptors for ELR-positive CXC chemokines which include growth-regulated oncogene alpha (GRO-alpha) and interleukin-8 (IL-8). GRO-alpha is considered to influence proliferation of cultured oligodendrocyte progenitors (OLPs). Using RT-PCR we show here that the oligodendrocyte precursor cell line CG-4 expresses both CXCR1 and CXCR2. Furthermore we demonstrate that both CG-4 cells and primary cultures of rat OLPs are immunoreactive for CXCR2, the potential receptor for GRO-alpha. This finding demonstrates that the chemokine/chemokine receptor system is probably also involved in the regulation of oligodendroglial cells during developmental processes and may even have implications for inflammatory demyelinating diseases like multiple sclerosis

136. Pahan K, Sheikh FG, Liu X, Hilger S, McKinney M, Petro TM (2001) Induction of nitric-oxide synthase and activation of NF-kappaB by interleukin-12 p40 in Microglial cells. J.Biol.Chem. 276:7899-7905
     Abstract: Interleukin-12 (IL-12) is composed of two different subunits, p40 and p35. Expression of p40 mRNA but not that of p35 mRNA in excessive amount in the central nervous system of patients with multiple sclerosis (MS) suggests that IL-12 p40 may have a role in the pathogenesis of the disease. However, the mode of action of p40 is completely unknown. Because nitric oxide produced from the induction of nitric-oxide synthase (iNOS) also plays a vital role in the pathophysiology of MS, the present study was undertaken to explore the role of p40 in the induction of NO production and the expression of iNOS in Microglia. Both IL-12 and p40(2), the p40 homodimer, dose-dependently induced the production of NO in BV-2 Microglial cells. This induction of NO production was accompanied by an induction of iNOS protein and mRNA. Induction of NO production by the expression of mouse p40 cDNA but not that of the mouse p35 cDNA suggests that the p40 but not the p35 subunit of IL-12 is involved in the expression of iNOS. In addition to BV-2 glial cells, p40(2) also induced the production of NO in mouse primary Microglia and peritoneal macrophages. However, both IL-12 and p40(2) were unable to induce the production of NO in mouse primary astrocytes. Because activation of NF-kappaB is important for the expression of iNOS, we investigated the effect of p40(2) on the activation of NF-kappaB. Induction of the DNA binding as well as the transcriptional activity of NF-kappaB by p40(2) and inhibition of p40(2)-induced expression of iNOS by SN50, a cell-permeable peptide carrying the nuclear localization sequence of p50 NF-kappaB, but not by SN50M, a nonfunctional peptide mutant, suggests that p40(2) induces the expression of iNOS through the activation of NF-kappaB. This study delineates a novel role of IL-12 p40 in inducing the expression of iNOS in Microglial cells, which may participate in the pathogenesis of neuroinflammatory diseases

137. Palma JP, Kim BS (2001) Induction of selected chemokines in glial cells infected with Theiler's virus. J.Neuroimmunol. 117:166-170
     Abstract: To elucidate the early events in Theiler's virus-induced demyelination, a model for human multiple sclerosis (MS), chemokine gene activation in the central nervous system (CNS) resident cells upon viral infection was investigated. Viral infection selectively upregulated RANTES and IP-10 gene expression in primary astrocyte cultures and broader chemokine genes in oligodendrocyte and Microglia cultures. Both RANTES and IP-10 were stimulated by proinflammatory cytokine interferon-gamma (IFNgamma), but only RANTES by tumor necrosis factor alpha (TNFalpha), suggesting that virus infection induces chemokines overlapping with those inducible by proinflammatory cytokines. These results suggest that glial cells, astrocytes in particular, may be critical for early recruitment of inflammatory cells in the initiation of virus-induced, immune-mediated demyelination

138. Pender MP, Rist MJ (2001) Apoptosis of inflammatory cells in immune control of the nervous system: role of glia. Glia 36:137-144
     Abstract: The elimination of inflammatory cells within the central nervous system (CNS) by apoptosis plays an important role in protecting the CNS from immune-mediated damage. T cells, B cells, macrophages, and Microglia all undergo apoptosis in the CNS. The apoptotic elimination of CNS-reactive T cells is particularly important, as these cells can recruit and activate other inflammatory cells. T-cell apoptosis contributes to the resolution of CNS inflammation and clinical recovery from attacks of experimental autoimmune encephalomyelitis (EAE), an animal model of the demyelinating disease multiple sclerosis (MS). T-cell apoptosis in the CNS in EAE occurs in both an antigen-specific and an antigen-nonspecific manner. In antigen-specific T-cell apoptosis, it is proposed that T cells that recognize their antigen in the CNS, such as CNS-reactive T cells, are deleted by the process of activation-induced apoptosis after activation of the T-cell receptor. This may result from the ligation of T-cell death receptors (such as CD95 (Fas) or tumor necrosis factor (TNF) receptor 1) by CD95 ligand (CD95L) or TNF expressed by the same T cell or possibly by Microglia, astrocytes or neurons. Inadequate costimulation of the T cell by antigen-presenting glial cells may render T cells susceptible to activation-induced apoptosis. T cells expressing CD95 may also die in an antigen-nonspecific manner after interacting with glial cells expressing CD95L. Other mechanisms for antigen-nonspecific T-cell apoptosis include the endogenous release of glucocorticosteroids, deprivation of interleukin-2, and the release of nitric oxide by macrophages or glia. Apoptosis of autoreactive T cells in the CNS is likely to be important in preventing the development of autoimmune CNS diseases such as MS

139. Penninger JM, Irie-Sasaki J, Sasaki T, Oliveira-dos-Santos AJ (2001) CD45: new jobs for an old acquaintance. Nat.Immunol. 2:389-396
     Abstract: Identified as the first and prototypic transmembrane protein tyrosine phosphatase (PTPase), CD45 has been extensively studied for over two decades and is thought to be important for positively regulating antigen-receptor signaling via the dephosphorylation of Src kinases. However, new evidence indicates that CD45 can function as a Janus kinase PTPase that negatively controls cytokine-receptor signaling. A point mutation in CD45, which appears to affect CD45 dimerization, and a genetic polymorphism that affects alternative CD45 splicing are implicated in autoimmunity in mice and multiple sclerosis in humans. CD45 is expressed in multiple isoforms and the modulation of specific CD45 splice variants with antibodies can prevent transplant rejections. In addition, loss of CD45 can affect Microglia activation in a mouse model for Alzheimer's disease. Thus, CD45 is moving rapidly back into the spotlight as a drug target and central regulator involved in differentiation of multiple hematopoietic cell lineages, autoimmunity and antiviral immunity

140. Peterson JW, Bo L, Mork S, Chang A, Trapp BD (2001) Transected neurites, apoptotic neurons, and reduced inflammation in cortical multiple sclerosis lesions. Ann.Neurol. 50:389-400
     Abstract: multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system that causes motor, sensory, and cognitive deficits. The present study characterized demyelinated lesions in the cerebral cortex of MS patients. One hundred twelve cortical lesions were identified in 110 tissue blocks from 50 MS patients. Three patterns of cortical demyelination were identified: Type I lesions were contiguous with subcortical white matter lesions; Type II lesions were small, confined to the cortex, and often perivascular; Type III lesions extended from the pial surface to cortical layer 3 or 4. Inflammation and neuronal pathology were studied in tissue from 8 and 7 patients, respectively. Compared to white matter lesions, cortical lesions contained 13 times fewer CD3-positive lymphocytes (195 vs 2,596/mm3 of tissue) and 6 times fewer CD68-positive Microglia/macrophages (11,948 vs 67,956/mm3 of tissue). Transected neurites (both axons and dendrites) occurred at a density of 4,119/mm3 in active cortical lesions, 1,107/mm3 in chronic active cortical lesions, 25/mm3 in chronic inactive cortical lesions, 8/mm3 in myelinated MS cortex, and 1/mm3 in control cortex. In active and chronic active cortical lesions, activated Microglia closely apposed and ensheathed apical dendrites, neurites, and neuronal perikarya. In addition, apoptotic neurons were increased significantly in demyelinated cortex compared to myelinated cortex. These data support the hypothesis that demyelination, axonal transection, dendritic transection, and apoptotic loss of neurons in the cerebral cortex contribute to neurological dysfunction in MS patients

141. Portis JL (2001) Genetic determinants of neurovirulence of murine oncornaviruses. Adv.Virus Res. 56:3-38

142. Prineas JW, Kwon EE, Cho ES, Sharer LR, Barnett MH, Oleszak EL, Hoffman B, Morgan BP (2001) Immunopathology of secondary-progressive multiple sclerosis. Ann.Neurol. 50:646-657
     Abstract: Twenty-three plaques obtained at early autopsy from 2 patients with secondary-progressive multiple sclerosis were examined immunohistochemically for Microglia/macrophages, and for immunoglobulins and components of activated complement. Most of the lesions examined in both cases exhibited evidence of low-grade active demyelination of an unusual type (frustrated phagocytosis) in periplaque white matter. This included linear groups of Microglia engaging short segments of disrupted myelin that were associated with deposits of C3d, an opsonin formed during complement activation. Similar Microglia/C3d/myelin profiles were not observed in newly forming lesions in cases of acute multiple sclerosis or other central white matter diseases. As C3d coupling is known to increase the immunogenicity of potential antigens enormously, present findings point to disrupted myelin close to plaques as a possible source of the putative multiple sclerosis antigen. Ongoing myelin destruction found in a high proportion of old, established plaques was surprising. It suggests that slowly expanding lesions (progressive plaques), in which ongoing myelin breakdown occurs in the absence of florid perivascular cell cuffing or other histological signs of acute inflammation, contribute to disease progression in cases of secondary-progressive multiple sclerosis

143. Redwine JM, Buchmeier MJ, Evans CF (2001) In vivo expression of major histocompatibility complex molecules on oligodendrocytes and neurons during viral infection. Am.J.Pathol. 159:1219-1224
     Abstract: Demyelination in multiple sclerosis and in animal models is associated with infiltrating CD8+ and CD4+ T cells. Although oligodendrocytes and axons are damaged in these diseases, the roles T cells play in the demyelination process are not completely understood. Antigen-specific CD8+ T cell lysis of target cells is dependent on interactions between the T cell receptor and major histocompatibility complex (MHC) class I-peptide complexes on the target cell. In the normal central nervous system, expression of MHC molecules is very low but often increases during inflammation. We set out to precisely define which central nervous system cells express MHC molecules in vivo during infection with a strain of murine hepatitis virus that causes a chronic, inflammatory demyelinating disease. Using double immunofluorescence labeling, we show that during acute infection with murine hepatitis virus, MHC class I is expressed in vivo by oligodendrocytes, neurons, Microglia, and endothelia, and MHC class II is expressed only by Microglia. These data indicate that oligodendrocytes and neurons have the potential to present antigen to T cells and thus be damaged by direct antigen-specific interactions with CD8+ T lymphocytes

144. Reynolds R, Cenci dB, I, Dawson M, Levine J (2001) The response of adult oligodendrocyte progenitors to demyelination in EAE. Prog.Brain Res. 132:165-174
     Abstract: Cells with the phenotypic characteristics of oligodendrocyte progenitors (NG2+/PDGF alpha R+/O4+) are found throughout the adult mammalian CNS in numbers similar to Microglia. They are a reactive glial cell population and respond to demyelination by increasing in number, thereby repopulating the lesion site with cells capable of differentiating into remyelinating oligodendrocytes. Direct evidence that they differentiate into remyelinating cells is missing, although this is the most likely scenario. Cells with the same phenotype are found in normal human CNS tissue and also in chronic MS lesions. Further studies on this intriguing cell type are necessary in order to understand the molecular signals involved in their reaction to injury, particularly in multiple sclerosis

145. Ruprecht K, Kuhlmann T, Seif F, Hummel V, Kruse N, Bruck W, Rieckmann P (2001) Effects of oncostatin M on human cerebral endothelial cells and expression in inflammatory brain lesions. J.Neuropathol.Exp.Neurol. 60:1087-1098
     Abstract: Oncostatin M (OSM) is a member of the interleukin (IL)-6 cytokine family and modulates inflammatory responses. Here we investigated the role of OSM as an immunoregulatory factor for human cerebral endothelial cells (HCEC). Using RT-PCR we detected transcripts of the receptor components involved in OSM signaling, gp130, OSM receptor (OSMR)-beta, and leukemia inhibitory factor receptor (LIFR), in HCEC. A parallel FACS analysis revealed surface expression of gp130 and OSMR-beta, but not of LIFR on these cells. Functionally, OSM upregulated intercellular adhesion molecule-1, but did not induce vascular cell adhesion molecule-1 in HCEC. Further, OSM upregulated IL-6 and monocyte chemoattractant protein (MCP)-1, whereas IL-8 was unaffected. Combined application of tumor necrosis factor (TNF)-alpha and OSM synergistically enhanced IL-6 and MCP-1 production, but downregulated TNF-alpha-induced IL-8. As OSM regulated molecules relevant in inflammatory brain diseases, we investigated its expression in normal and pathological human brains. OSM was detected by immunohistochemistry in brains from multiple sclerosis patients in Microglia, reactive astrocytes, and infiltrating leukocytes, whereas in normal brains and noninflammatory neurological diseases. immunoreactivity was absent from the parenchyma. These data suggest that immunoregulatory functions in human cerebral endothelial cells may be a mechanism by which OSM participates in the pathophysiology of inflammatory brain disease

146. Smith ME (2001) Phagocytic properties of Microglia in vitro: implications for a role in multiple sclerosis and EAE. Microsc.Res.Tech. 54:81-94
     Abstract: The Microglial cell, after many years of neglect, has become recognized as the sole representative cell of the immune system that resides in the normal central nervous system. While normally dormant, Microglia can be activated by secretory substances or signals associated with disease or injury, and becomes a phagocytic cell, which also produces its own injurious molecules. In the activating process, its morphology is changed from a resting process-bearing cell, into a rounded amoebic form, and displays new or increased amounts of functional markers, such as receptors and Class I and Class II MHC molecules. Microglia prepared from newborn mice or rats for tissue culture are already activated, and can be used for studies of their phagocytic properties. Although they can phagocytize foreign substances, their uptake and metabolism of myelin are emphasized here, in keeping with their role in demyelinating diseases. A number of receptors have been implicated and appear to be important in the attachment to, and ingestion of, myelin particles in vitro, including the Fc, complement, macrophage scavenger, and the Galectin-3/MAC-2 receptors, although the alpha2-macroglobulin/low-density lipoprotein receptor and mannose receptors have also been suggested as participants in myelin phagocytosis. Certain cytokines and adhesion molecules also regulate the phagocytic activity of Microglia. Comparative in vitro studies of phagocytosis by peritoneal macrophages and Microglia have shown that the two kinds of cells respond differently to regulatory molecules, and it is concluded that they have different innate properties. The role of Microglia in the demyelinative diseases experimental autoimmune encephalomyelitis and multiple sclerosis is emphasized here, and the possible means of intervention in the process leading to myelin destruction is discussed. Published 2001 Wiley-Liss, Inc

147. Solanky M, Maeda Y, Ming X, Husar W, Li W, Cook S, Dowling P (2001) Proliferating oligodendrocytes are present in both active and chronic inactive multiple sclerosis plaques. J.Neurosci.Res. 65:308-317
     Abstract: The proliferation marker Ki-67 labels cell nuclei in the G(1), S, M, and G(2) phases of the cell cycle. We used Ki-67 immunohistochemistry to quantify proliferating glial cells in brain tissue sections from twenty-four patients, comprised of multiple sclerosis, normal brains, and other neurological disease controls. Glial proliferation was greatly increased in MS lesions when compared with control brain white matter. Both actively demyelinating/early remyelinating plaques and chronic inactive plaques of long standing often displayed large numbers of glial cells in the proliferative cycle. The bulk of these proliferating cells were of oligodendroglial lineage in the MS plaques. Ki-67 positive macrophage/Microglial lineage cells were largely restricted to acute lesions. The finding of increased numbers of proliferating oligodendroglia in most MS plaques, regardless of disease duration or activity state, indicates that the MS brain is capable of recruiting unexpectedly large numbers of new oligodendrocytes over long periods of time. The factors within the MS plaque microenvironment that provoke new oligodendrocyte generation and their subsequent loss still need to be identified

148. Stangel M, Compston A (2001) Polyclonal immunoglobulins (IVIg) modulate nitric oxide production and Microglial functions in vitro via Fc receptors. J.Neuroimmunol. 112:63-71
     Abstract: Controlled trials in multiple sclerosis (MS) and case reports in acute demyelinating encephalomyelitis (ADEM) have shown that intravenous immunoglobulins (IVIg) are of therapeutic benefit in central nervous system (CNS) inflammatory diseases. Studies in experimental autoimmune encephalomyelitis (EAE) have suggested these effects are mediated by modulation of the cytokine network and T cell responses. However, there are no data on the influence of IVIg on the local immune reaction in the CNS, the site of inflammation in EAE. We have therefore studied the effect of IVIg on cultured rat Microglia, the main immune cell in the CNS. IVIg increased nitric oxide (NO) production in a dose-dependent manner in Microglia stimulated with IFNgamma. The increase was only marginal in LPS-treated cells, and no effect was seen in untreated Microglia or after stimulation with TNFalpha or PMA. This enhancement of NO production depended on the Fc portion of IVIg and could be abrogated by the pharmacological inhibition of Syk and phosphatidylinositol 3-kinase, two enzymes involved in the signalling cascade of Fc receptors. TNFalpha secretion was dose-dependently stimulated by IVIg in both untreated Microglia and after stimulation with LPS or IFNgamma. Again, this effect was mediated through the Fc portion. Finally, we showed that Fc receptor-mediated phagocytosis was inhibited by IVIg, presumably by blockade of the Fc receptor. These different effects may protect oligodendrocytes from antibody mediated phagocytosis and on the other hand could terminate the immune reaction by induction of apoptosis in infiltrating T cells via NO and TNFalpha. We propose that IVIg, in addition to known effects on the peripheral immune system, may also modulate the local immune reaction in CNS inflammatory disease

149. Subramanian S, Bourdette DN, Corless C, Vandenbark AA, Offner H, Jones RE (2001) T lymphocytes promote the development of bone marrow-derived APC in the central nervous system. J.Immunol. 166:370-376
     Abstract: Certain cells within the CNS, Microglial cells and perivascular macrophages, develop from hemopoietic myelomonocytic lineage progenitors in the bone marrow (BM). Such BM-derived cells function as CNS APC during the development of T cell-mediated paralytic inflammation in diseases such as experimental autoimmune encephalomyelitis and multiple sclerosis. We used a novel, interspecies, rat-into-mouse T cell and/or BM cell-transfer method to examine the development and function of BM-derived APC in the CNS. Activated rat T cells, specific for either myelin or nonmyelin Ag, entered the SCID mouse CNS within 3-5 days of cell transfer and caused an accelerated recruitment of BM-derived APC into the CNS. Rat APC in the mouse CNS developed from transferred rat BM within an 8-day period and were entirely sufficient for induction of CNS inflammation and paralysis mediated by myelin-specific rat T cells. The results demonstrate that T cells modulate the development of BM-derived CNS APC in an Ag-independent fashion. This previously unrecognized regulatory pathway, governing the presence of functional APC in the CNS, may be relevant to pathogenesis in experimental autoimmune encephalomyelitis, multiple sclerosis, and/or other CNS diseases involving myelomonocytic lineage cells

150. Talbot PJ, Arnold D, Antel JP (2001) Virus-induced autoimmune reactions in the CNS. Curr.Top.Microbiol.Immunol. 253:247-271

151. Tilgner J, Volk B, Kaltschmidt C (2001) Continuous interleukin-6 application in vivo via macroencapsulation of interleukin-6-expressing COS-7 cells induces massive gliosis. Glia 35:234-245
     Abstract: The inflammatory cytokine interleukin-6 (IL-6) was found in senile plaques of Alzheimer's patients and might be involved in the pathology of Parkinson's disease and multiple sclerosis. Interestingly, an astocytosis is also found in these neurodegenerative disorders. To evaluate the direct effects of IL-6 in vivo on glial cells, we created a new in vivo model. IL-6 and mock-transfected (control group) COS-7 cells were encapsulated in a poly-acryl-nitril membrane for implantation into the rat striatum. Afterward, the host immune reaction to the membrane without encapsulated cells and the biological action of IL-6-producing capsules was evaluated. Animals with an implanted membrane without cells showed a moderate astrocytosis 5 days after the operation. Furthermore, Microglia and T-cells could be detected and after 30 days the astrocytosis decreased to a small layer around the membrane. In comparison to the control group, which received a sham operation, our results demonstrate that the response of glial cells is caused by the mechanical damage of the surgical procedure itself rather than due to the introduced membrane material. In contrast, we found a massive proliferation and activation of astrocytes and Microglia after 10 days by IL-6-secreting capsules, indicating that IL-6 is involved in the induction of gliosis. Control animals that received encapsulated mock-transfected COS-7 cells showed only a weak response. These data point to an involvement of IL-6 in the proliferation and activation of glial cells as seen in neurodegenerative disorders

152. Trebst C, Sorensen TL, Kivisakk P, Cathcart MK, Hesselgesser J, Horuk R, Sellebjerg F, Lassmann H, Ransohoff RM (2001) CCR1+/CCR5+ mononuclear phagocytes accumulate in the central nervous system of patients with multiple sclerosis. Am.J.Pathol. 159:1701-1710
     Abstract: Mononuclear phagocytes (monocytes, macrophages, and Microglia) are considered central to multiple sclerosis (MS) pathogenesis. Molecular cues that mediate mononuclear phagocyte accumulation and activation in the central nervous system (CNS) of MS patients may include chemokines RANTES/CCL5 and macrophage inflammatory protein-1alpha/CCL3. We analyzed expression of CCR1 and CCR5, the monocyte receptors for these chemokines, on circulating and cerebrospinal fluid CD14+ cells, and in MS brain lesions. Approximately 70% of cerebrospinal fluid monocytes were CCR1+/CCR5+, regardless of the presence of CNS pathology, compared to less than 20% of circulating monocytes. In active MS lesions CCR1+/CCR5+ monocytes were found in perivascular cell cuffs and at the demyelinating edges of evolving lesions. Mononuclear phagocytes in early demyelinating stages comprised CCR1+/CCR5+ hematogenous monocytes and CCR1-/CCR5- resident Microglial cells. In later stages, phagocytic macrophages were uniformly CCR1-/CCR5+. Cultured in vitro, adherent monocytes/macrophages up-regulated CCR5 and down-regulated CCR1 expression, compared to freshly-isolated monocytes. Taken together, these findings suggest that monocytes competent to enter the CNS compartment derive from a minority CCR1+/CCR5+ population in the circulating pool. In the presence of ligand, these cells will be retained in the CNS. During further activation in lesions, infiltrating monocytes down-regulate CCR1 but not CCR5, whereas Microglia up-regulate CCR5

153. Werner P, Pitt D, Raine CS (2001) multiple sclerosis: altered glutamate homeostasis in lesions correlates with oligodendrocyte and axonal damage. Ann.Neurol. 50:169-180
     Abstract: Glutamate excitotoxicity, recently demonstrated in an animal model of multiple sclerosis (MS), is evoked by altered glutamate homeostasis. In the present study, we investigated the major regulating factors in glutamate excitotoxicity by immunohistochemistry in MS and control white matter with markers for glutamate production (glutaminase), glutamate transport (GLAST, GLT-1 and EAAT-1), glutamate metabolism (glutamate dehydrogenase [GDH] and glutamine synthetase [GS]), axonal damage (SMI 32) and CNS cell types. Active MS lesions showed high-level glutaminase expression in macrophages and Microglia in close proximity to dystrophic axons. Correlation between glutaminase expression and axonal damage was confirmed experimentally in animals. White matter from other inflammatory neurologic diseases displayed glutaminase reactivity, whereas normals and noninflammatory conditions showed none. All three glutamate transporters were expressed robustly, mainly on oligodendrocytes, in normal, control and MS white matter, except for GLT-1, which showed low-level expression around active MS lesions. GS and GDH were present in oligodendrocytes in normal and non-MS white matter but were absent from both active and chronic silent MS lesions, suggesting lasting metabolic impediments. Thus, imbalanced glutamate homeostasis contributes to axonal and oligodendroglial pathology in MS. Manipulation of this imbalance may have therapeutic import

154. Wilms H, Rosenstiel P, Sievers J, Deuschl G, Lucius R (2001) Cerebrospinal fluid from patients with neurodegenerative and neuroinflammatory diseases: no evidence for rat glial activation in vitro. Neurosci.Lett. 314:107-110
     Abstract: To determine the possible contribution of glial cells via oxidative stress/cytokine secretion in the pathogenesis of Parkinson's disease (PD), Alzheimer disease (AD), amyotrophic lateral sclerosis (ALS) or multiple sclerosis (MS) the concentration of nitric oxide (NO) (by the Griess method) and Interleukin-6 (IL-6) (by enzyme-linked immunosorbent assay) were measured in resting rat Microglial and astrocytic cell culture supernatants stimulated by cerebrospinal fluid (CSF) (dilution 1:4, 1:10) from patients with the aforementioned diseases. Neither the concentration of NO (optical density at 450 nm: control, 0.036+/-0.006; MS, 0.034+/-0.008; AD, 0.031+/-0.006; PD, 0.02+/-0.01; lipopolysaccharide (LPS), 0.26+/-0.018) nor the amount of IL-6 (ng/ml: control, 0.112+/-0.026; PD, 0.12+/-0.027; MS, 0.123+/-0.008; ALS, 0.137+/-0.01; LPS, 1.81+/-0.11) differed in any disease group from those of unaffected controls. These findings suggest that the stimuli for inflammatory activation of glia are quite localized and not present in sufficient concentrations in the CSF of affected patients

155. Wolf SA, Gimsa U, Bechmann I, Nitsch R (2001) Differential expression of costimulatory molecules B7-1 and B7-2 on Microglial cells induced by Th1 and Th2 cells in organotypic brain tissue. Glia 36:414-420
     Abstract: Autoreactive T-cells are involved in demyelination, neurodegeneration, and the recruitment of peripheral macrophages and nonspecific activated T-cells in autoimmune diseases such as multiple sclerosis (MS). The ligation of costimulatory B7 molecules on Microglia with CD28/CTLA-4 on T-cells is thought to be crucial to the onset and course of MS and its rodent model experimental autoimmune encephalomyelitis (EAE). It is currently unclear as to how far the nature of infiltrating T-cells has an impact on the expression of the B7 molecules on Microglia, the resident antigen-presenting cells (APCs) of the brain. We studied the expression of B7-1 and B7-2 on Microglia after encounter with preactivated Th1 and Th2 cells from transgenic mice whose T-cells express a receptor (TCR) either specific to myelin basic protein (MBP) or ovalbumin (OVA) using murine organotypic entorhinal-hippocampal slice cultures (OEHSC). Our main finding was that Th1 cells downregulate the constitutive expression of B7-2 and induce B7-1 expression while Th2 cells do not induce this B7-1 upregulation. The main difference between MBP- and OVA-specific cells was seen in experiments were Th1 cells had direct contact to APCs but not to brain tissue. In contrast to MBP-specific Th1 cells, OVA-specific Th1 cells required the addition of antigen to upregulate B7-1 and downregulate B7-2. When the cells were allowed to have contact to brain tissue, no difference was seen in the pattern of B7 regulation between OVA- and MBP-specific T-cells. Our data suggest that T-cells are able to modulate B7 expression on Microglial cells in the brain independent of antigen presentation through TCR/MHC-II ligation but presumably by soluble mediators

156. Zavalishin IA, Zhuchenko TD, Peresedova AV (2001) [Pathogenesis and treatment of multiple sclerosis (state of the art in 2000)]. Vestn.Ross.Akad.Med.Nauk18-22
     Abstract: multiple sclerosis is universally accepted to be a multifactorial disease whose pathogenesis is due to a complex of immunopathological and pathochemical reactions. The key assumption is that only early stages of immunopathological chain reactions involve specific recognition of antigens by autoreactive T cells and antibodies. These early events trigger a demyelinating process at whose later stages of importance are macrophages and glial cells, particularly those of Microglia, which produce a great deal of biologically active substances and inflammatory mediators. A deeper insight into the pathogenesis of multiple sclerosis has provided new therapeutical approaches to treating this disease. In addition to that there are effective IFN-beta drugs (Betaferon, Rebif, Avonex) and Copaxone, other pathogenetically justified approaches are still under search. The next step of further studies is to identify subtypes of multiple sclerosis and to choose a therapy in accordance with its pathogenetical mechanisms

157. Zheng L, Calenoff MA, Dal Canto MC (2001) Astrocytes, not Microglia, are the main cells responsible for viral persistence in Theiler's murine encephalomyelitis virus infection leading to demyelination. J.Neuroimmunol. 118:256-267
     Abstract: The BeAn strain of Theiler's murine encephalomyelitis virus (TMEV) persists in the CNS and produces a chronic inflammatory demyelinating disease that is an animal model for human multiple sclerosis (MS). The mechanisms leading to TMEV-induced demyelination are still under study but most likely involve both immune-mediated and virus induced damage to cells in the CNS, both depending on viral persistence. It is therefore important to identify the cells in which continued virus production is permitted. In this study, we looked at virus infection in primary astrocytes, Microglia and oligodendrocytes, derived from brains of neonatal susceptible SJL/J mice. As evidenced by Western blots and immunocytochemistry, we were able to detect viral antigens in all these brain-derived cells. In addition, we extended the study to spinal cord tissues from mice suffering TMEV-induced disease. Immunohistochemistry staining with anti-TMEV sera and antibodies to specific cell markers detected viral antigens in all these cells. We then asked the question whether viral antigen present in these cells, particularly in Microglia/macrophages, represented true viral replication or not. By using different techniques, including immunoprecipitation experiments and the very sensitive method of negative RNA detection through RNase protection assay, we show that both astrocytes and oligodendroglia permit de novo viral replication and viral protein synthesis but with only minimal cytopathic effects. Of these two cell types, astrocytes carry the brunt of viral replication. In Microglia, on the other hand, viral replication is restricted since only minimal amounts of negative RNA copies can be demonstrated, while there are clear signs that some of these cells undergo apoptosis. These findings show that the main cell for viral replication is the astrocyte, rather than the Microglia/macrophage. Most of the viral antigen present in macrophages, therefore, is probably the result of phagocytosis, rather than actual viral replication. In view of the demonstrated presence of viral replication in astrocytes and of great amounts of viral antigens in Microglia/macrophages, it is possible that both types of cells act as antigen presenting cells during this immunopathological disease

158. Aldskogius H (2000) [Microglia--new target cells for neurological therapy]. Lakartidningen 97:3358-3362
     Abstract: Disturbances in the normal homeostasis of the central nervous system induce a localized activation of Microglia. This activation serves to isolate pathological processes from surrounding, intact nervous tissue. Concomitantly, healthy or minimally damaged nerve cells nearby may be negatively influenced by potent molecules released by activated Microglia. This situation appears to exist e.g. in ischemia, multiple sclerosis and Alzheimer's disease. Pharmacologic regulation of Microglial activity is therefore a rational approach to treatment of many central nervous system disorders

159. Alldinger S, Fonfara S, Kremmer E, Baumgartner W (2000) Up-regulation of the hyaluronate receptor CD44 in canine distemper demyelinated plaques. Acta Neuropathol.(Berl) 99:138-146
     Abstract: CD44 antigen (CD44), the principle cell surface receptor for hyaluronate, is up-regulated in the human demyelinating disease multiple sclerosis on fibrous astrocytes. As astrocytes are the main target cell of canine distemper virus (CDV), the consequences of a CDV infection on the CD44 expression and distribution in brains with spontaneous demyelinating canine distemper encephalitis (CDE) were of interest. Thirteen acute, 35 subacute, and 11 chronic plaques of nine dogs with immunohistologically confirmed CDE and brains of control dogs were included in the study. For light microscopy, 5-micron-thick serial sections were stained with H&E and incubated with monoclonal antibodies (mAbs) against CD44 and canine distemper virus nucleoprotein and polyclonal antibodies (pAbs) against glial fibrillary acidic protein (GFAP) and myelin basic protein (MBP). For immunoelectron microscopy, 90-nm-thick sections were double stained with anti-GFAP and anti-CD44 mAbs to specify CD44-expressing structures. In controls, CD44 was diffusely distributed in the white matter and single meningeal cells exhibited a marginal expression of the antigen. In acute and more prominently in subacute demyelinating encephalitis, there was a plaque-associated up-regulation of CD44 which paralleled GFAP. In chronic demyelinating lesions, a reduction of CD44 associated with a loss of GFAP-positive astrocytes was noted. Additionally, in chronic plaques, CD44 was expressed on the cell membrane of perivascular mononuclear cells. Immunoelectron microscopically, in controls, CD44 was rarely demonstrated on astrocytic cell processes. In contrast, in brains with CDE CD44 was found on the cell membrane of broadened astrocytic cell processes. In summary, CD44 is up-regulated on astrocytes in the early phase of CDE and seems to represent a marker for the activation of immune cells in the late phase of the infection

160. Bacon KB, Harrison JK (2000) Chemokines and their receptors in neurobiology: perspectives in physiology and homeostasis. J.Neuroimmunol. 104:92-97
     Abstract: Chemokines are a large family of small secreted proteins (8-14 kDa) associated with the trafficking of leukocytes in physiological immunosurveillance as well as inflammatory cell recruitment in different disease processes. A limited repertoire of chemokines and their specific cognate receptors are detectable in cells of the CNS such as Microglia, astrocytes and neurons under physiological conditions. Coupled with distinct patterns of ligand and receptor expression in various pathologies including multiple sclerosis, trauma, neuro-AIDS, Alzheimer's disease, stroke, neuro- and glioblastomas, such phenomena have fueled the strong belief that chemokines must fulfill significant and potentially diverse functional roles in the CNS

161. Banati RB, Newcombe J, Gunn RN, Cagnin A, Turkheimer F, Heppner F, Price G, Wegner F, Giovannoni G, Miller DH, Perkin GD, Smith T, Hewson AK, Bydder G, Kreutzberg GW, Jones T, Cuzner ML, Myers R (2000) The peripheral benzodiazepine binding site in the brain in multiple sclerosis: quantitative in vivo imaging of Microglia as a measure of disease activity. Brain 123 ( Pt 11):2321-2337
     Abstract: This study identifies by microautoradiography activated Microglia/macrophages as the main cell type expressing the peripheral benzodiazepine binding site (PBBS) at sites of active CNS pathology. Quantitative measurements of PBBS expression in vivo obtained by PET and [(11)C](R)-PK11195 are shown to correspond to animal experimental and human post-mortem data on the distribution pattern of activated Microglia in inflammatory brain disease. Film autoradiography with [(3)H](R)-PK11195, a specific ligand for the PBBS, showed minimal binding in normal control CNS, whereas maximal binding to mononuclear cells was found in multiple sclerosis plaques. However, there was also significantly increased [(3)H](R)-PK11195 binding on activated Microglia outside the histopathologically defined borders of multiple sclerosis plaques and in areas, such as the cerebral central grey matter, that are not normally reported as sites of pathology in multiple sclerosis. A similar pattern of [(3)H](R)-PK11195 binding in areas containing activated Microglia was seen in the CNS of animals with experimental allergic encephalomyelitis (EAE). In areas without identifiable focal pathology, immunocytochemical staining combined with high-resolution emulsion autoradiography demonstrated that the cellular source of [(3)H](R)-PK11195 binding is activated Microglia, which frequently retains a ramified morphology. Furthermore, in vitro radioligand binding studies confirmed that Microglial activation leads to a rise in the number of PBBS and not a change in binding affinity. Quantitative [(11)C](R)-PK11195 PET in multiple sclerosis patients demonstrated increased PBBS expression in areas of focal pathology identified by T(1)- and T(2)-weighted MRI and, importantly, also in normal-appearing anatomical structures, including cerebral central grey matter. The additional binding frequently delineated neuronal projection areas, such as the lateral geniculate bodies in patients with a history of optic neuritis. In summary, [(11)C](R)-PK11195 PET provides a cellular marker of disease activity in vivo in the human brain

162. Becher B, Prat A, Antel JP (2000) Brain-immune connection: immuno-regulatory properties of CNS-resident cells. Glia 29:293-304
     Abstract: Even though the immune privileged status of the central nervous system (CNS) limits access of systemic immune cells through the blood brain barrier (BBB), an immune response can occur in this compartment with or without major breach of the BBB. In this review, we consider properties of resident cells of the CNS, that participate in regulating the neural antigen (Ag)-directed immune responses implicated in autoimmune diseases such as multiple sclerosis (MS). Under such conditions, the CNS is usually viewed as the target or victim of the immune assault, because such immune responses are thought to be initiated and regulated within the systemic immune compartment. The CNS-endogenous cells may themselves, however, initiate, regulate and sustain an immune response. We consider the immune regulatory functions within the CNS in terms of events occurring within the CNS parenchyma (Microglia, astroglia) and at the vascular interface. These regulatory functions involve antigen presentation to T cells and polarization of the cytokine response of these cells. Such responses may contribute not only to the overall tissue injury in primary immune disorders but also in a wide range of traumatic, ischemic and degenerative processes

163. Beyer M, Gimsa U, Eyupoglu IY, Hailer NP, Nitsch R (2000) Phagocytosis of neuronal or glial debris by Microglial cells: upregulation of MHC class II expression and multinuclear giant cell formation in vitro. Glia 31:262-266
     Abstract: Most CNS pathologies are accompanied by the occurrence of activated, phagocytic Microglial cells. We intended to investigate whether (1) isolated Microglial cells removed from the CNS cytokine network sustain their capacity to acquire an activated phenotype when challenged with cellular or noncellular debris; and (2) different substrates lead to different patterns of Microglial activation. It was observed that although removed from their usual surroundings Microglial cells preserve their ability to transform to an amoeboid morphology, form multinucleated giant cells, and enhance their expression of MHC class II when exposed to membranes of neuronal or glial origin. Furthermore, cellular substrates derived from primary hippocampal neuronal cultures, neuroblastic cells (B50), or glial cells were all able to induce similar morphological changes and enhanced expression of MHC class II. In contrast, phagocytosis of Latex beads induced an amoeboid morphology but no increase in the expression of immunologically relevant molecules. Interferon-beta (IFN-beta), a substance clinically used in the treatment of the relapsing-remitting form of multiple sclerosis, was shown to inhibit the phagocytosis-induced upregulation of MHC-class II. In summary, phagocytic Microglial cells are independent from the CNS cytokine network in their transition from a resting to an activated phenotype; and different cellular substrates, regardless whether they are of neuronal, glial, or even malignant origin, result in similar morphological and functional changes

164. Boven LA, Montagne L, Nottet HS, De Groot CJ (2000) Macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and RANTES mRNA semiquantification and protein expression in active demyelinating multiple sclerosis (MS) lesions. Clin.Exp.Immunol. 122:257-263
     Abstract: MS is a demyelinating disease characterized by infiltration of monocytes and lymphocytes into the brain parenchyma, destruction of oligodendrocytes and loss of myelin. Since chemokines play a major role in the migration of monocytes and T cells, we here investigated the expression of the CC chemokines MIP-1alpha, MIP-1beta, and RANTES in brain tissue from MS patients using reverse transcriptase-polymerase chain reaction techniques. Both MIP-1beta as well as RANTES were found to be significantly elevated in brain tissue of MS patients. In addition, MIP-1alpha was also increased, although not significantly. Immunohistochemistry revealed that, whereas RANTES was mainly localized in reactive astrocytes, MIP-1alpha and MIP-1beta immunoreactivity was predominantly found in perivascular and parenchymal macrophages, containing myelin degradation products. Thus, chemokines appear to be associated with MS and an increased chemokine expression may further enhance disease progression by attracting more leucocytes into the brain parenchyma and by activation of effector functions of astrocytes and Microglial cells

165. Cammer W (2000) Effects of TNFalpha on immature and mature oligodendrocytes and their progenitors in vitro. Brain Res. 864:213-219
     Abstract: Tumor necrosis factor alpha (TNFalpha) appears to take part in the pathogenesis of multiple sclerosis and to contribute to the degeneration of oligodendrocytes as well as neurons. TNFalpha is produced by Microglia and astrocytes, which also produce hormones and cytokines that influence its biological activity. Thus, in mixed cultures the effects of exogenous TNFalpha might be modified by products of astrocytes and Microglia. The effects of TNFalpha in oligodendrocyte-enriched cultures are reported below. We prepared the cultures by shaking oligodendrocytes off primary mixed glial-cell cultures from brains of 2-day-old rats at 7 days in vitro and plating them (0 days post-shake, DPS). Platelet-derived growth factor and fibroblast growth factor were included in the media at 1-5 DPS in order to encourage proliferation. At 2 DPS media were added with no TNFalpha (controls) or 1000, 2000 or 5000 U/ml of TNFalpha, and at 5 DPS media were replaced with fresh serum-free media. Cultures were fixed with 4% paraformaldehyde at 5, 7, 9 and 12 DPS and immunostained. Oligodendrocyte progenitors were not reduced in numbers immediately after the incubation with TNFalpha (i. e. at 5 DPS). However, after an additional 4 days in culture fewer progenitors remained in the cultures that had been treated with TNFalpha than in the untreated cultures. In the absence of the growth factors there were fewer progenitors, but their numbers also were reduced by TNFalpha. Maturation to the myelin basic protein (MBP)-positive stage was inhibited by about 36% at 9 DPS by 1000-2000 U/ml of TNFalpha, while numbers of O4+/MBP- precursors were unaffected. It is interesting that the steady-state number of O4-positive precursors was unchanged by TNFalpha at 9 DPS, when there were reductions in the numbers of A2B5-positive progenitors and MBP-positive mature oligodendrocytes. That observation suggests that the rates of proliferation, death and maturation are controlled by multiple factors, with a particularly vulnerable time at the maturation to the MBP-positive stage. At 5000 U/ml TNFalpha the specific effect on maturation was overtaken cytotoxicity. These data and a summary of the literature suggest that inhibition of MBP expression is sensitive to lower TNFalpha concentrations and incubation times than is cell survival. Specific effects on numbers of MBP-positive cells, morphology and MBP expression occur at 1000-2000 U/ml for 48-72 h or at up to 10000 U/ml for</=24 h, and the deficits remain after removal of the TNFalpha

166. Chabot S, Yong VW (2000) Interferon beta-1b increases interleukin-10 in a model of T cell-Microglia interaction: relevance to MS. Neurology 55:1497-1505
     Abstract: BACKGROUND: The modes of action of interferon beta (IFN-beta) in MS remain unclear, but enhanced levels of the anti-inflammatory cytokine interleukin-10 (IL-10) in the CSF of patients with MS may be a marker of its prognostic efficacy. OBJECTIVE: To examine potential mechanisms by which IL-10 may be increased by IFN-ss in the milieu of the CNS. METHODS: A model of T cell interaction with Microglia in vitro was used. Production of cytokines was monitored by measuring the levels of various cytokine proteins, using ELISA. RESULTS: Pretreatment of T cells with IFN-beta potentiates the production of IL-10 when they interact with adult human Microglia, human fetal Microglia, or U937 cells treated with phorbol-12-myristate-13-acetate (PMA) and IFN-gamma. The enhancing effect of IFN-beta on IL-10 requires cell-cell contact, but does not seem to depend on pathways implicated in Microglia-T cell interactions, involving CD40, CD23, and B7. In contrast to IL-10, IFN-beta inhibits the production of other cytokines, including tumor necrosis factor-alpha (TNF-alpha), IL-1beta, IL-4, IL-12, and IL-13. CONCLUSIONS: The increase of IL-10 in Microglia-T cell interaction by IFN-beta together with a decrease of other cytokines may lead to a noninflammatory milieu in the CNS. This mechanism could contribute to the efficacy of IFN-beta in MS

167. Chang A, Nishiyama A, Peterson J, Prineas J, Trapp BD (2000) NG2-positive oligodendrocyte progenitor cells in adult human brain and multiple sclerosis lesions. J.Neurosci. 20:6404-6412
     Abstract: multiple sclerosis (MS) is characterized by multifocal loss of myelin, oligodendrocytes, and axons. Potential MS therapies include enhancement of remyelination by transplantation or manipulation of endogenous oligodendrocyte progenitor cells. Characteristics of endogenous oligodendrocyte progenitors in normal human brain and in MS lesions have not been studied extensively. This report describes the distribution of cells in sections from normal adult human brain and MS lesions by using antibodies directed against NG2, an integral membrane chondroitin sulfate proteoglycan expressed by oligodendrocyte progenitor cells. Stellate-shaped NG2-positive cells were detected in the white and gray matter of normal adult human brain and appeared as abundant as, but distinct from, astrocytes, oligodendrocytes, and Microglia. Stellate-shaped or elongated NG2-positive cells also were detected in chronic MS lesions. A subpopulation of the elongated NG2-positive cells expressed the putative apoptotic signaling molecule p75(NTR). TUNEL-positive cells in three active, nine chronic active, and four chronic inactive lesions, however, were p75(NTR)-negative. These studies identify cells with phenotypic markers of endogenous oligodendrocyte progenitors in the mature human CNS and suggest that functional subpopulations of NG2-positive cells exist in MS lesions. Endogenous oligodendrocyte progenitor cells may represent a viable target for future therapies intended to enhance remyelination in MS patients

168. Deininger MH, Kremsner PG, Meyermann R, Schluesener HJ (2000) Differential cellular accumulation of transforming growth factor-beta1, -beta2, and -beta3 in brains of patients who died with cerebral malaria. J.Infect.Dis. 181:2111-2115
     Abstract: In cerebral malaria (CM), pathologic cytokine expression patterns are thought to contribute to disruption of the blood-brain barrier, inflammation, and astrocytic scar formation. Expression of transforming growth factor (TGF)-beta1, -beta2, and -beta3 was analyzed in the brains of 7 patients who died with CM and in 8 control patients. In the brains of patients with CM, there were significantly (P=.0003) more TGF-beta1-immunoreactive astrocytes adjacent to brain vessels with deposition of malarial pigment, significantly (P=.0081) more TGF-beta2-expressing macrophages/Microglial cells in glioses of ring hemorrhages and Durck's granulomas, and significantly (P=.0022) more TGF-beta3-expressing smooth-muscle cells and endothelial cells of brain vessels with sequestration. It is concluded that focal accumulation of TGF-beta1, -beta2, and -beta3 provides evidence for their involvement in the reorganization process of the brain parenchyma, immunologic dysfunction, and endothelial cell activation in patients with CM

169. Dittel BN (2000) Evidence that Fas and FasL contribute to the pathogenesis of experimental autoimmune encephalomyelitis. Arch.Immunol.Ther.Exp.(Warsz.) 48:381-388
     Abstract: The well established and characterized animal model for the human demyelinating autoimmune disease multiple sclerosis (MS) is known as experimental autoimmune encephalomyelitis (EAE). EAE is clinically characterized by focal areas of inflammation and demyelination and an infiltrate composed of large numbers of lymphocytes and macrophages, often found in a perivascular localization but also throughout the central nervous system (CNS). Active immunization of mice with several different protein components of myelin, including myelin basic protein (MBP), proteolipid protein (PLP) and myelin oligodendrocyte glycoprotein (MOG), are capable of eliciting an immune response resulting in the quintessential symptoms of EAE: ascending paralysis involving the tail and then the limbs. Depending on the mouse strain and myelin antigen utilized, the disease course can be acute or chronic relapsing, characterized by a rapid onset of hind limb weakness that commonly progresses to paralysis, followed by spontaneous remission starting 7-10 days after the initial appearance of symptoms. EAE can also be induced passively by the adoptive transfer of in vitro activated CD4+ T cell clones or lines, typically of the Th1 phenotype, into irradiated susceptible recipients. The mechanisms involved in the cellular pathogenesis leading to paralysis and demyelination have been extensively studied and are primarily mediated by CD4+ T cells of the Th1 phenotype, with specificity for myelin antigens. Following activation, Th1 CD4 T cells produce in abundance the inflammatory cytokines TNF-alpha, IFN-gamma and lymphotoxin alpha (LT-alpha, also know as TNF-beta). IFN-gamma production is highly correlated with encephalitogenicity and may contribute to disease by up-regulation of adhesion molecules on endothelial cells, facilitating migration of lymphocytes into the CNS; by induction of major histocompatibility complex (MHC) class I and MHC class II molecules on astrocytes, Microglial cells and brain endothelium, facilitating antigen (Ag) presentation in the CNS; and by activation of macrophages, leading to production of nitric oxide, a potent cytotoxic molecule. TNF-alpha and LT-alpha are both members of the TNF family of molecules and cause cell death by apoptosis following interaction with their counter-receptors, the TNFR1 and TNFR2, leading to a cascade of proteolytic events culminating in the blebbing of the cytoplasmic membrane, nuclear condensation and DNA fragmentation. Consequently, the production of TNF-alpha and LT-alpha by Th1 clones has been correlated with encephalitogenic potential and antibodies (Abs) to both prevents EAE upon transfer of encephalitogenic clones. Even though substantial evidence exists for the role of inflammatory cytokines in the pathogenesis of EAE, other mechanisms of myelin destruction are thought to exist. To date, many reports have implicated a role for the cell death-inducing ligand pair Fas and Fas-ligand (FasL)

170. Drew PD, Chavis JA (2000) Female sex steroids: effects upon Microglial cell activation. J.Neuroimmunol. 111:77-85
     Abstract: multiple sclerosis occurs more commonly in females than males. However, the mechanisms resulting in gender differences in multiple sclerosis are unknown. Activated Microglia are believed to contribute to multiple sclerosis pathology, perhaps in part due to production of nitric oxide (NO) and TNF-alpha, molecules which can be toxic to cells including oligodendrocytes. The current study demonstrates that the female sex steroids estriol, beta-estradiol and progesterone inhibit lipopolysaccharide (LPS) induction of nitric oxide (NO) production by primary rat Microglia and by the mouse N9 Microglial cell line. These hormones act by inhibiting the production of inducible nitric oxide synthase (iNOS) which catalyses the synthesis of NO. Estriol likely inhibits iNOS gene expression since the hormone blocks LPS induction of iNOS RNA levels. The pro-inflammatory cytokines IFN-gamma and TNF-alpha are believed to be important modulators of multiple sclerosis. Here, we demonstrate that estrogens and progesterone also inhibit NO production by Microglial cells activated in response to these cytokines. Activated Microglia elicit TNF-alpha in addition to NO and we further demonstrate that estrogens and progesterone repress TNF-alpha production by these cells. Finally, estriol and progesterone, at concentrations consistent with late pregnancy, inhibit NO and TNF-alpha production by activated Microglia, suggesting that hormone inhibition of Microglial cell activation may contribute to the decreased severity of multiple sclerosis symptoms commonly associated with pregnancy

171. Edwards JA, Denis F, Talbot PJ (2000) Activation of glial cells by human coronavirus OC43 infection. J.Neuroimmunol. 108:73-81
     Abstract: multiple sclerosis (MS) is an immune-mediated demyelinating disease that could be triggered by a viral infection. Coronaviruses induce an MS-like disease in rodents, are neuroinvasive in humans and can infect primary cultures of human astrocytes and Microglia. Infection of the human astrocytic cell line U-373MG by the OC43 strain of human coronavirus caused an upregulation of IL-6, TNF-alpha, and MCP-1 mRNA expression. This virus also modulated the activity of matrix metalloproteinases-2 and -9 and augmented nitric oxide production in both U-373MG cells and the human Microglial cell line CHME-5. Thus, a coronaviral infection of glial cells could lead to the production of inflammatory molecules that have been associated with central nervous system pathologies such as MS

172. Emerson MR, LeVine SM (2000) Heme oxygenase-1 and NADPH cytochrome P450 reductase expression in experimental allergic encephalomyelitis: an expanded view of the stress response. J.Neurochem. 75:2555-2562
     Abstract: Oxidative stress is implicated in the pathogenesis of experimental allergic encephalomyelitis (EAE), a model for multiple sclerosis. Heme oxygenase-1 (HO-1) is a heat shock protein induced by oxidative stress. HO-1 metabolizes the pro-oxidant heme to the antioxidant biliverdin and CO. HO-1 requires electrons, donated by NADPH cytochrome P450 reductase (henceforth, reductase), for catalytic activity. EAE was induced with a peptide of proteolipid protein in SJL mice, and the expression of HO-1 and reductase in the hindbrain was analyzed. HO-1 protein levels were significantly increased in EAE animals compared with control mice. HO-1 expression was present in ameboid macrophages, reactive Microglia, and astrocytes in white matter tracks. Bergmann glia and ameboid macrophages also were occasionally stained in the molecular layer of the cerebellum. Unlike HO-1, reductase protein levels decreased with disease severity. HO-1 and reductase were associated with each other in endoplasmic reticulum micelles, suggesting that the decrease in reductase does not interfere with its association with HO-1. In cells that express HO-1, the association of reductase with HO-1 should competitively inhibit the interaction of reductase with cytochrome P450 isozymes and thereby limit free radical production as the latter two enzymes act cooperatively to produce superoxide. The increase in HO-1 together with the decrease in reductase may be part of a common defense mechanism attempting to minimize tissue damage in several neurological conditions

173. Frigerio S, Silei V, Ciusani E, Massa G, Lauro GM, Salmaggi A (2000) Modulation of fas-ligand (Fas-L) on human Microglial cells: an in vitro study. J.Neuroimmunol. 105:109-114
     Abstract: The expression of Fas-Ligand (Fas-L) on Microglia could be relevant in multiple sclerosis immunopathology. The present study was performed to evaluate in vitro the expression of Fas-L in human Microglial cells both unstimulated and after stimulation with IFN-gamma, beta-IFN-1b and beta-IFN-1b+IFN-gamma. Cells were stimulated for 6,12, 24 and 48 h. Surface Fas-L was evaluated by flow cytometry, total Fas-L by Western blot, whereas mRNA for Fas-L was measured by RT-PCR. We also evaluated the capacity of Microglial cells to induce, in vitro, apoptosis on Fas-positive T leukemia Jurkat cells. Our results showed a constitutive expression of Fas-L on Microglia. IFN-gamma downregulated the expression of the molecule, while beta-IFN-1b and beta-IFN-1b+IFN- gamma did not. The amount of surface Fas-L was related to the ability of Microglial cells to induce apoptosis in Fas-positive target cells, which was partly inhibited by blockade of the Fas-Fas-L pathway

174. Gao X, Gillig TA, Ye P, D'Ercole AJ, Matsushima GK, Popko B (2000) Interferon-gamma protects against cuprizone-induced demyelination. Mol.Cell Neurosci. 16:338-349
     Abstract: Evidence suggests that interferon-gamma (IFN-gamma), a proinflammatory cytokine secreted by activated T lymphocytes, contributes a deleterious effect to immune-mediated demyelinating disorders such as multiple sclerosis and experimental autoimmune encephalomyelitis (EAE). Nevertheless, mouse strains that are normally resistant to EAE induction become susceptible when the gene encoding either IFN-gamma or its receptor is mutated, demonstrating that the role that this cytokine plays in demyelinating disorders is complex. We have examined the effect of IFN-gamma in a chemically induced model of CNS demyelination. Mice that receive through their diet the copper chelator cuprizone display extensive demyelination of the corpus callosum. Remarkably, transgenic mice that ectopically express low levels of IFN-gamma in the CNS did not display evidence of demyelination when treated with cuprizone, nor did they shows signs of oligodendroglial death, astrogliosis, or microgliosis, which are typically seen in treated animals. Myelin protein gene expression was, however, dramatically reduced in both the treated control and the transgenic animals, indicating that demyelination is not an obligatory consequence of a large diminution of myelin protein synthesis. Interestingly, the CNS of the IFN-gamma-expressing mice contained elevated levels of insulin-like growth factor I, which has been demonstrated to have a protective effect against the demyelinating action of cuprizone

175. Gimsa U, Peter SV, Lehmann K, Bechmann I, Nitsch R (2000) Axonal damage induced by invading T cells in organotypic central nervous system tissue in vitro: involvement of Microglial cells. Brain Pathol. 10:365-377
     Abstract: Neuroinflammation in the course of multiple sclerosis and experimental autoimmune encephalomyelitis results in demyelination and, recently demonstrated, axonal loss. Invading neuroantigen specific T cells are the crucial cellular elements in these processes. Here we demonstrate that invasion of activated T cells induces a massive Microglial attack on myelinated axons in entorhinal-hippocampal slice cultures. Flow cytometry analysis of activation markers revealed that the activation state of invading MBP-specific T cells was significantly lower in comparison to PMA-activated T cells. Moreover, MBP-specific T cells showed a significantly lower secretion of IFN-gamma. Conversely, MBP-specific T cells displayed a significantly higher potential to trigger activation of Microglial cells, i.e. upregulation of MHC class II and ICAM-1 expression, and, most importantly, Microglial phagocytosis of pre-traced axons. Our data suggest that this was mediated via specific cellular interactions of T cells and Microglial cells since IFN-gamma alone was not sufficient to induce axonal damage while such damage was apparent in response to TNF-alpha which is released by activated Microglial cells. TNF-alpha secretion by both T cell populations was negligible. Thus, MBP-specific T cells which invade nervous tissue in the course of neuroinflammation are more effective in axon-damaging recruiting Microglial cells than activated T cells of other specificities

176. Hisahara S, Araki T, Sugiyama F, Yagami K, Suzuki M, Abe K, Yamamura K, Miyazaki J, Momoi T, Saruta T, Bernard CC, Okano H, Miura M (2000) Targeted expression of baculovirus p35 caspase inhibitor in oligodendrocytes protects mice against autoimmune-mediated demyelination. EMBO J. 19:341-348
     Abstract: The mechanisms underlying oligodendrocyte (OLG) loss and the precise roles played by OLG death in human demyelinating diseases such as multiple sclerosis (MS), and in the rodent model of MS, experimental autoimmune encephalomyelitis (EAE), remain to be elucidated. To clarify the involvement of OLG death in EAE, we have generated transgenic mice that express the baculovirus anti-apoptotic protein p35 in OLGs through the Cre-loxP system. OLGs from cre/p35 transgenic mice were resistant to tumor necrosis factor-alpha-, anti-Fas antibody- and interferon-gamma-induced cell death. cre/p35 transgenic mice were resistant to EAE induction by immunization with the myelin oligodendrocyte glycoprotein. The numbers of infiltrating T cells and macrophages/Microglia in the EAE lesions were significantly reduced, as were the numbers of apoptotic OLGs expressing the activated form of caspase-3. Thus, inhibition of apoptosis in OLGs by p35 expression alleviated the severity of the neurological manifestations observed in autoimmune demyelinating diseases

177. Holz A, Bielekova B, Martin R, Oldstone MB (2000) Myelin-associated oligodendrocytic basic protein: identification of an encephalitogenic epitope and association with multiple sclerosis. J.Immunol. 164:1103-1109
     Abstract: Myelin-associated oligodendrocytic basic protein (MOBP) is an abundant myelin constituent expressed exclusively by oligodendrocytes, the myelin-forming cells of the CNS. We report that MOBP causes experimental allergic encephalomyelitis and is associated with multiple sclerosis. First, we note that purified recombinant MOBP inoculated into SJL/J mice produces CNS disease. Tests of overlapping peptides spanning the murine MOBP molecule map the encephalitogenic site to amino acids 37-60. MOBP-induced experimental allergic encephalomyelitis shows a severe clinical course and is characterized by a prominent CD4+ T lymphocyte infiltration and a lesser presence of CD8+ T cells and Microglia/macrophages around vessels and in the white matter of the CNS. Second, PBL obtained from patients with relapsing/remitting multiple sclerosis mount a proliferative response to human MOBP, especially at amino acids 21-39. This response equals or exceeds the response to myelin basic protein and an influenza virus hemagglutinin peptide, both serving as internal controls. Thus, a novel myelin Ag, MOBP aa 37-60, plays a role in rodent autoimmune CNS disease, and its human MOBP counterpart is associated with the human demyelinating disease multiple sclerosis

178. Kantarci OH, Atkinson EJ, Hebrink DD, McMurray CT, Weinshenker BG (2000) Association of a myeloperoxidase promoter polymorphism with multiple sclerosis. J.Neuroimmunol. 105:189-194
     Abstract: Myeloperoxidase (MPO) generates hypochlorous acid and other reactive oxygen intermediates leading to tissue damage. MPO is expressed in macrophages-Microglia in multiple sclerosis (MS) lesions. A G-->A substitution that abolishes an SP1 transcription factor consensus sequence in the promoter reduces gene expression. We studied the association of the genetic variant with MS. We did not find an association with gender, age at onset, susceptibility to, or the course and severity of MS in a population-based sample of 122 patients from Olmsted County

179. Krogsgaard M, Wucherpfennig KW, Cannella B, Hansen BE, Svejgaard A, Pyrdol J, Ditzel H, Raine C, Engberg J, Fugger L, Canella B (2000) Visualization of myelin basic protein (MBP) T cell epitopes in multiple sclerosis lesions using a monoclonal antibody specific for the human histocompatibility leukocyte antigen (HLA)-DR2-MBP 85-99 complex. J.Exp.Med. 191:1395-1412
     Abstract: Susceptibility to multiple sclerosis (MS) is associated with the human histocompatibility leukocyte antigen (HLA)-DR2 haplotype, suggesting that major histocompatibility complex class II-restricted presentation of central nervous system-derived antigens is important in the disease process. Antibodies specific for defined HLA-DR2-peptide complexes may therefore be valuable tools for studying antigen presentation in MS. We have used phage display technology to select HLA-DR2-peptide-specific antibodies from HLA-DR2-transgenic mice immunized with HLA-DR2 molecules complexed with an immunodominant myelin basic protein (MBP) peptide (residues 85-99). Detailed characterization of one clone (MK16) demonstrated that both DR2 and the MBP peptide were required for recognition. Furthermore, MK16 labeled intra- and extracellular HLA-DR2-MBP peptide complexes when antigen-presenting cells (APCs) were pulsed with recombinant MBP. In addition, MK16 inhibited interleukin 2 secretion by two transfectants that expressed human MBP-specific T cell receptors. Analysis of the structural requirement for MK16 binding demonstrated that the two major HLA-DR2 anchor residues of MBP 85-99 and the COOH-terminal part of the peptide, in particular residues Val-96, Pro-98, and Arg-99, were important for binding. Based on these results, the antibody was used to determine if the HLA-DR2-MBP peptide complex is presented in MS lesions. The antibody stained APCs in MS lesions, in particular Microglia/macrophages but also in some cases hypertrophic astrocytes. Staining of APCs was only observed in MS cases with the HLA-DR2 haplotype but not in cases that carried other haplotypes. These results demonstrate that HLA-DR2 molecules in MS lesions present a myelin-derived self-peptide and suggest that Microglia/macrophages rather than astrocytes are the predominant APCs in these lesions

180. Lane TE, Liu MT, Chen BP, Asensio VC, Samawi RM, Paoletti AD, Campbell IL, Kunkel SL, Fox HS, Buchmeier MJ (2000) A central role for CD4(+) T cells and RANTES in virus-induced central nervous system inflammation and demyelination. J.Virol. 74:1415-1424
     Abstract: Infection of C57BL/6 mice with mouse hepatitis virus (MHV) results in a demyelinating encephalomyelitis characterized by mononuclear cell infiltration and white matter destruction similar to the pathology of the human demyelinating disease multiple sclerosis. The contributions of CD4(+) and CD8(+) T cells in the pathogenesis of the disease were investigated. Significantly less severe inflammation and demyelination were observed in CD4(-/-) mice than in CD8(-/-) and C57BL/6 mice (P < or = 0.002 and P < or = 0.001, respectively). Immunophenotyping of central nervous system (CNS) infiltrates revealed that CD4(-/-) mice had a significant reduction in numbers of activated macrophages/Microglial cells in the brain compared to the numbers in CD8(-/-) and C57BL/6 mice, indicating a role for these cells in myelin destruction. Furthermore, CD4(-/-) mice displayed lower levels of RANTES (a C-C chemokine) mRNA transcripts and protein, suggesting a role for this molecule in the pathogenesis of MHV-induced neurologic disease. Administration of RANTES antisera to MHV-infected C57BL/6 mice resulted in a significant reduction in macrophage infiltration and demyelination (P < or = 0.001) compared to those in control mice. These data indicate that CD4(+) T cells have a pivotal role in accelerating CNS inflammation and demyelination within infected mice, possibly by regulating RANTES expression, which in turn coordinates the trafficking of macrophages into the CNS, leading to myelin destruction

181. Luo Y, Fischer FR, Hancock WW, Dorf ME (2000) Macrophage inflammatory protein-2 and KC induce chemokine production by mouse astrocytes. J.Immunol. 165:4015-4023
     Abstract: Astrocytes are specialized cells of the CNS that are implicated in the pathogenesis of multiple sclerosis and experimental allergic encephalomyelitis. In acute and relapsing-remitting experimental allergic encephalomyelitis, the neutrophil chemoattractant CXC chemokines macrophage-inflammatory protein (MIP)-2 and KC are associated with reactive astrocytes in the parenchyma. In vitro treatment of primary astrocyte cultures with nanomolar concentrations of MIP-2 or KC markedly up-regulated expression of the monocyte/T cell chemoattractants monocyte chemoattractant protein-1, inflammatory protein-10, and RANTES by a mechanism that includes stabilization of mRNA. Production of TNF-alpha and IL-6 transcripts were also noted, as was autocrine induction of MIP-2 and KC message. In addition, low levels of MIP-1alpha and MIP-1beta were induced following treatment with MIP-2 or KC. These effects are specific to astrocytes as MIP-2 treatment of Microglial cells failed to elicit chemokine production. The astrocyte chemokine receptor for MIP-2 has 2.5 nM affinity for ligand. Astrocytes from CXCR2-deficient mice still respond to KC and MIP-2, indicating the presence of an alternative or novel high affinity receptor for these ligands. We propose that this KC/MIP-2 chemokine cascade may contribute to the persistence of mononuclear cell infiltration in demyelinating autoimmune diseases

182. McManus CM, Liu JS, Hahn MT, Hua LL, Brosnan CF, Berman JW, Lee SC (2000) Differential induction of chemokines in human Microglia by type I and II interferons. Glia 29:273-280
     Abstract: Chemokines are secreted proteins that function as chemoattractants, mediating the recruitment of specific subsets of leukocytes to sites of tissue damage and immunological reactions. Chemokines may also function as antiviral agents, since viruses such as human immunodeficiency virus type 1 (HIV-1) use chemokine receptors as co-receptors for viral entry. This study examines whether virus-induced interferon, IFNbeta, or immune-related interferon, IFNgamma, affects the production of beta-chemokines by CNS Microglia and peripheral monocytes. When IFNbeta was used as the stimulus, induction of MIP-1alpha, MIP-1beta, MCP-1, and RANTES mRNA and protein was observed within 12 h of stimulation in Microglia. By contrast, when IFNgamma was used as the stimulus, only MCP-1 was induced. IFNbeta stimulation of blood monocytes resulted in upregulation of MIP-1alpha, MIP-1beta, and MCP-1. Thus, type I and II interferons differentially regulate beta-chemokines in human fetal Microglia and peripheral blood monocytes. These observations may have relevance for the therapeutic activity of IFNbeta in multiple sclerosis and for the antiviral effects of IFNbeta for HIV-1 infection of monocytes and Microglia

183. Merodio M, Irache JM, Eclancher F, Mirshahi M, Villarroya H (2000) Distribution of albumin nanoparticles in animals induced with the experimental allergic encephalomyelitis. J.Drug Target 8:289-303
     Abstract: Experimental allergic encephalomyelitis (EAE) is an autoimmune disease characterised by a disruption of the blood-brain barrier (BBB), demyelination and a relevant inflammatory reaction with an intense infiltration of macrophages. These neurological disorders are similar to those observed in the multiple sclerosis (MS) disease. The use of different liposomes and adeno-associated virus has been proposed for improving the treatment of this pathogenesis. The aim of this work was to evaluate the potential and capacity of albumin nanoparticles to reach the central nervous system (CNS) in EAE-induced rats. For this purpose, the distribution of biotinylated nanoparticles within the CNS was studied. Albumin carriers were mainly found in the lumbar portion of the spinal cord, overlying the meningeal and perivascular areas. The optic chiasma, iris and the area of the Purkinje cells of the cerebellum revealed also an intense presence of these carriers. Finally, immunohistochemical studies also revealed that circulating macrophages (ED1), which migrate to damaged sites, and resident activated Microglial cells (OX42) were involved in the distribution of albumin nanoparticles. In summary, the use of nanoparticles may be useful for the design of new pharmaceutical dosage forms able to target the lesions associated with alterations of the BBB

184. Minami M, Satoh M (2000) [Chemokines as mediators for intercellular communication in the brain]. Nippon Yakurigaku Zasshi 115:193-200
     Abstract: Chemokines constitute a large and still growing family of structurally-related small (8-10 kDa) cytokines that have chemotactic activity for leukocytes. Recently, some receptors for chemokines were reported to be used as a co-receptor by HIV at infection. In addition to their well-established role in inflammatory response and recently-reported role as a co-receptor for HIV, recent data suggest that chemokines and their receptors physiologically and pathologically play crucial roles as the mediators for intercellular communication among the cells intrinsic to and recruited into the brain; i.e., neurons, astrocytes, Microglia, endothelial cells and leukocytes. Some chemokines such as SDF-1 and fractalkine are constitutively produced in the brain, implicating that they have an important role in maintenance of CNS homeostasis or determination of the patterning of neurons and/or glial cells in developing brain and normal adult brain. Chemokines such as MCP-1, MIP-1 alpha and CINC were shown to be induced by various neuroinflammatory stimuli, suggesting that they are involved in various neurodegenerative diseases such as multiple sclerosis, Alzheimer's disease, stroke and AIDS dementia syndrome. Chemokines and their receptors are potential targets for therapeutic intervention in neurodegenerative diseases

185. Olsson T, Lundberg C, Lidman O, Piehl F (2000) Genetic regulation of nerve avulsion-induced spinal cord inflammation. Ann.N.Y.Acad.Sci. 917:186-196
     Abstract: In the animal model for multiple sclerosis (MS), experimental autoimmune encephalitis (EAE), genetic loci correlating with incidence or severity of disease are located both within and outside of the major histocompatibility complex (MHC). Whereas polymorphisms within MHC class I and II molecules are likely to be a major determinant of MHC gene influence in rat EAE, it is still unclear how non-MHC gene regions influence disease. Genetic control of inflammation can hypothetically be either general or specific for a particular target tissue. For the latter, gene regulation of pathomechanisms in the CNS could affect reactivity of Microglia or astrocytes, local cytokine/chemokine production, or even neuronal vulnerability. We have obtained strong support for this notion by observations of rat strain-dependent variation in the inflammatory response after ventral root avulsion, a model in which mainly non-antigen-specific elements of the immune system promote inflammation. A comparison of strains with similar MHC haplotypes on different backgrounds and strains with different MHC haplotypes on the same background, respectively, demonstrates that the inflammatory phenotype is regulated mainly by non-MHC genes. Interestingly, different features of the inflammatory response, such as induction of MHC class II expression, glial activation, cytokine expression, and neuronal vulnerability, varied between rat strains and were largely independent of each other. The genetic control of several basic features of inflammation in the CNS is of great relevance not only for MS/EAE, but also for several other neurological conditions with inflammatory components such as cerebrovascular and neurogenerative dieases and trauma

186. Penkowa M, Hidalgo J (2000) Metallothionein I+II expression and their role in experimental autoimmune encephalomyelitis. Glia 32:247-263
     Abstract: We examined the expression and roles of neuroprotective metallothionein-I+II (MT-I+II) in the rat CNS in experimental autoimmune encephalomyelitis (EAE), an animal model for the human autoimmune disease, multiple sclerosis (MS). EAE caused significant macrophage activation, T-lymphocyte infiltration, and astrogliosis in spinal cord, brain stem, and cerebellum, which peaked 14-18 days after immunization. The remission of symptoms and histopathological changes began at days 19-21 and were completed by days 30-40. MT-I+II expression was increased significantly in EAE infiltrates. In order to study the effects of increased MT levels, we administered Zn-MT-II intraperitoneally (i.p.) to rats during EAE. Clinically, Zn-MT-II treatment reduced the severity of EAE symptoms and mortality in a time- and dose-dependent manner. Histopathologically, Zn-MT-II increased reactive astrogliosis and decreased macrophages and T lymphocytes significantly in the CNS. In spleen sections, the number of macrophages both in control and EAE-sensitized rats was reduced by Zn-MT-II, while the number of lymphocytes remained unaltered by Zn-MT-II. Therefore, we suggest that MT-II has peripheral mechanisms of action on macrophages, while T lymphocytes are affected locally in the CNS. During EAE, oxidative stress was decreased by Zn-MT-II, which could contribute to the diminished clinical scores observed. None of the effects caused by Zn-MT-II could be attributable to the zinc content. These results suggest MT-I+II as potentially useful factors for the treatment of EAE/MS

187. Pouly S, Antel JP, Ladiwala U, Nalbantoglu J, Becher B (2000) Mechanisms of tissue injury in multiple sclerosis: opportunities for neuroprotective therapy. J.Neural Transm.Suppl193-203
     Abstract: Development of neuroprotective therapies for multiple sclerosis is dependent on defining the precise mechanisms whereby immune effector cells and molecules are able to induce relatively selective injury of oligodendrocytes (OLs) and their myelin membranes. The selectivity of this injury could be conferred either by the properties of the effectors or the targets. The former would involve antigen specific recognition by either antibody or T cell receptor of the adaptive immune system. OLs are also susceptible to non antigen restricted injury mediated by components of the innate immune system including macrophages/Microglia and NK cells. Target related selectivity could reflect the expression of death inducing surface receptors (such as Fas or TNFR-1) required for interaction with effector mediators and subsequent intracellular signaling pathways, including the caspase cascade. Development of therapeutic delivery systems, which would reach the site of disease activity within the CNS, will permit the administration of inhibitors either of the cell death pathway or of effector target interaction and opens new avenues to neuroprotection approach

188. Rottman JB, Slavin AJ, Silva R, Weiner HL, Gerard CG, Hancock WW (2000) Leukocyte recruitment during onset of experimental allergic encephalomyelitis is CCR1 dependent. Eur.J.Immunol. 30:2372-2377
     Abstract: We have shown that macrophages and Microglia present within demyelinating plaques of patients with multiple sclerosis (MS) are immunoreactive for the chemokine receptor CCR1 and its ligand, macrophage inflammatory protein-1alpha. To test the importance of CCR1 to the pathogenesis of MS, we studied the progression of experimental allergic encephalomyelitis (EAE) in CCR1(+/+) vs. CCR1(-/-) mice. After immunization with myelin oligodendrocyte glycoprotein (MOG) 35-55 peptide, nearly all CCR1(+/+) mice developed EAE (95% incidence, severity 2.5+/-0.1), whereas CCR1(-/-) mice had less severe disease (55% incidence, p<0.001; severity 1. 2+/-0.2, p<0.001). CCR1(+/+) mice showed elevated brain mRNA for the chemokines immune protein (IP)-10, RANTES and monocyte chemoattractant protein-1 prior to disease onset, whereas only IP-10 mRNA was elevated in CCR1(-/-) mice. Both groups of mice had comparable in vitro lymphocyte proliferation and cytokine production upon stimulation with MOG peptide, and similar cutaneous hypersensitivity responses to 2,4-dinitrofluorobenzene, suggesting that CCR1(-/-) mice were not systemically immunosuppressed. These data demonstrate that deletion of a chemokine receptor is at least partially protective in EAE, and suggest that targeting of CCR1 may be of therapeutic significance clinically

189. Shoham S, Youdim MB (2000) Iron involvement in neural damage and microgliosis in models of neurodegenerative diseases. Cell Mol.Biol.(Noisy.-le-grand) 46:743-760
     Abstract: In several neurodegenerative diseases, iron accumulates at sites of brain pathology. Since post-mortem examination cannot distinguish whether iron accumulation caused the damage or resulted from damage, it is necessary to manipulate iron in animal and tissue culture models to assess its causal role(s). However, only in models of Parkinson's disease and of global ischemia, iron deprivation (ID) or iron-chelators have been used to protect from damage. In these studies, documentation of microgliosis was not performed even though several lines of evidence converge to suggest that activation of Microglia is an important source of oxidative stress. In the kainate model of epilepsy, we found that ID protected the olfactory cortex, thalamus and hippocampus and attenuated microgliosis, whereas iron supplementation to ID rats increased damage and microgliosis in the above regions. In the hilus of the hippocampal dentate gyrus, even though no cell loss was observed, ID attenuated microgliosis and iron-supplementation increased it. Thus there is a tight relationship between iron and microgliosis. In addition, iron+zinc supplementation dramatically increased damage to hippocampal CA1 whereas zinc supplementation alone had no effect. This study demonstrates an anatomically unique interaction of iron and zinc, which may lead to new insights to neurodegeneration in epilepsy

190. Simpson J, Rezaie P, Newcombe J, Cuzner ML, Male D, Woodroofe MN (2000) Expression of the beta-chemokine receptors CCR2, CCR3 and CCR5 in multiple sclerosis central nervous system tissue. J.Neuroimmunol. 108:192-200
     Abstract: multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS) characterised by perivascular inflammatory cell infiltrates and plaques of demyelination. Chemokines have been shown to play an important role in the activation and directional migration of cells to sites of CNS inflammation. The action of chemokines requires the expression of their complementary chemokine receptors by their target cells. We have examined the expression of the beta-chemokine receptors CCR2, CCR3 and CCR5 in post-mortem MS CNS tissue using single- and double-labelling immunocytochemistry techniques. Low levels of CCR2, CCR3 and CCR5 were expressed by Microglial cells throughout control CNS tissue. In chronic active MS lesions CCR2, CCR3 and CCR5 were associated with foamy macrophages and activated Microglia. CCR2 and CCR5 were also present on large numbers of infiltrating lymphocytes. A smaller number of CCR3-positive lymphocytes were present, but we also noted CCR3 and CCR5 on astrocytes in five of the 14 cases of MS investigated, particularly associated with processes around vessels and at the glia limitans. Ligands for CCR2 and CCR3 include MCP-1 and MCP-3 which were co-localised around vessels with the infiltrating leukocytes, but were also present in unaffected areas of cortex. The elevated expression of CCR2, CCR3 and CCR5 in the CNS in MS suggests these beta-chemokine receptors and their ligands play a role in the pathogenesis of MS

191. Stangel M, Joly E, Scolding NJ, Compston DA (2000) Normal polyclonal immunoglobulins ('IVIg') inhibit Microglial phagocytosis in vitro. J.Neuroimmunol. 106:137-144
     Abstract: Phagocytosis removes pathogens and tissue debris during inflammatory reactions, but also plays an important role in autoimmune reactions. The main phagocytes in the central nervous system (CNS) are Microglial cells that are activated during CNS inflammation. In the treatment of inflammatory demyelinating diseases like multiple sclerosis (MS), administration of intravenous immunoglobulins (IVIg) has become a promising immunomodulatory therapy. Although a large number of potential mechanisms for the effects of IVIg has been suggested, the precise mode of action in CNS inflammation is unknown. We assessed the influence of IVIg on phagocytosis and endocytosis in Microglia in vitro. IVIg had little effect on non-specific phagocytosis of latex particles in untreated Microglia, while there was a dose-dependent inhibition in Microglia activated with LPS and IFNgamma. Endocytosis of soluble myelin basic protein (MBP) was downregulated by IVIg in both untreated and activated Microglia. The effect was mediated by an F(ab')(2) preparation of immunoglobulins, suggesting that Fc receptor-mediated phagocytosis is not involved. Intact IVIg, but not F(ab')(2) fragments also suppressed Fc receptor-mediated phagocytosis of opsonised erythrocytes in both untreated and activated Microglia. These results show that IVIg can inhibit the phagocytic activity of Microglia via different mechanisms. Such an effect could contribute to the immunomodulatory capacity of IVIg in inflammatory CNS diseases

192. Sun D, Tani M, Newman TA, Krivacic K, Phillips M, Chernosky A, Gill P, Wei T, Griswold KJ, Ransohoff RM, Weller RO (2000) Role of chemokines, neuronal projections, and the blood-brain barrier in the enhancement of cerebral EAE following focal brain damage. J.Neuropathol.Exp.Neurol. 59:1031-1043
     Abstract: The role of focal brain damage as a trigger for autoimmune inflammation in multiple sclerosis (MS) is unclear. In this study we examine mechanisms by which experimental autoimmune encephalomyelitis (EAE) is enhanced by focal brain damage. EAE was produced in Lewis rats by footpad inoculation; focal brain damage, in the form of a cortical cryolesion (cryolesion-EAE), was induced 8 days post-inoculation (d.p.i.). The distribution of inflammation and chemokine production in cryolesion-EAE and EAE-only were compared. Inflammation in the brain, measured by immunocytochemistry for T lymphocytes (W3/13) and Microglial activation (MHC class II -OX6), was significantly enhanced in cryolesion-EAE 11-15 d.p.i. (p < 0.01-0.05) but by 20-40 d.p.i., equated with EAE-only. Inflammation in cryolesion-EAE related to breakdown of the blood-brain barrier (BBB) at the site of the cryolesion and also to the corticospinal tracts and thalamus, reflecting the afferent and efferent neuronal connections with the cryolesioned cortex. Semiquantitative RT/PCR dot-blot hybridization assay showed a 6-fold increase in mRNA for specific chemokines in the brain in cryolesion-EAE at 9 d.p.i. (MCP-1) and 11 d.p.i. (MCP-1 and MCP-5) with no significant increase in RANTES, GRO-alpha, or MIP-1alpha. By 14 d.p.i., the levels of MCP-1 and MCP-5 mRNA equated with EAE-only animals. These results suggest that enhancement and location of autoimmune inflammation in the brain following focal cortical injury initially involve chemokines such as the macrophage chemoattractants MCP-1 and MCP-5, and the activities of afferent and efferent neuronal connections with the site of damage. By analogy, similar factors may modulate or reactivate autoimmune inflammation in MS

193. Tan J, Town T, Mullan M (2000) CD45 inhibits CD40L-induced Microglial activation via negative regulation of the Src/p44/42 MAPK pathway. J.Biol.Chem. 275:37224-37231
     Abstract: It has been reported that ligation of CD40 with CD40 ligand (CD40L) results in Microglial activation as evidenced by p44/42 mitogen-activated protein kinase (MAPK) dependent tumor necrosis factor alpha (TNF-alpha) production. Previous studies have shown that CD45, a functional transmembrane protein-tyrosine phosphatase, is constitutively expressed at moderate levels on Microglial cells and this expression is greatly elevated on activated Microglia. To investigate the possibility that CD45 might modulate CD40L-induced Microglial activation, we treated primary cultured Microglial cells with CD40L and anti-CD45 antibody. Data show that cross-linking of CD45 markedly inhibits CD40L-induced activity of the Src family kinases Lck and Lyn. Further, co-treatment of Microglia with CD40L and anti-CD45 antibody results in significant inhibition of Microglial TNF-alpha production through inhibition of p44/42 MAPK activity, a downstream signaling event resulting from Src activation. Accordingly, primary cultured Microglial cells from mice deficient in CD45 demonstrate hyper-responsiveness to ligation of CD40, as evidenced by increased p44/42 MAPK activation and TNF-alpha production. Taken together, these results show that CD45 plays a novel role in suppressing CD40L-induced Microglial activation via negative regulation of the Src/p44/42 MAPK cascade

194. Williams KC, Zhao W, Politopoulou G, Male D, Hickey WF (2000) Inhibition of experimental allergic encephalomyelitis with an antibody that recognizes a novel antigen expressed on lymphocytes, endothelial cells, and Microglia. Lab Invest 80:313-326
     Abstract: Experimental allergic encephalomyelitis (EAE) is a frequently employed animal model of the human disease multiple sclerosis. EAE can be induced by adoptive transfer of CD4+ T cells that are specific for central nervous system (CNS) antigens, typically myelin proteins. Although the pathogenic mechanism or mechanisms responsible for the clinical signs and histological changes in EAE and multiple sclerosis are not fully defined, the entry of T lymphocytes and antigen recognition within the CNS are required. The present study describes the participation of a novel cell surface molecule with properties suggesting a role in cell-cell adhesion or co-stimulation, or both, in the development of EAE in the rat. The molecule is defined by the unique monoclonal antibody (mAb) TLD-4A2. The TLD-4A2 antigen is present on resting and activated T lymphocytes, activated CNS endothelial cells, and Microglia. The antigen is normally distributed in many tissues including lymph node, thymus, and spleen, as well as in the inflamed CNS. Both its pattern of tissue distribution and immunoprecipitation and immunoblotting studies suggest that the TLD-4A2 antigen is a novel molecule. Treatment of rats with the purified 4A2 mAb resulted in the inhibition of the clinical signs of EAE and also decreased the number T cells and macrophages accumulating in the CNS parenchyma. TLD-4A2 antibody did not seem to directly interfere with T cell viability in vivo, as demonstrated by the ability to recover and stimulate CD4+ encephalitogenic T cells from cervical lymph nodes of 4A2-treated animals. In vitro, the antibody partially blocked T cell proliferation assays. These data suggest that the TLD-4A2 mAb recognizes a novel molecule expressed on lymphocytes, endothelial cells, and macrophages that may play a role in hematogenous cell traffic and the initiation of CNS inflammation

195. Zhang GX, Baker CM, Kolson DL, Rostami AM (2000) Chemokines and chemokine receptors in the pathogenesis of multiple sclerosis. Mult.Scler. 6:3-13
     Abstract: In recent years we have seen growing evidence for the role of chemokines in the pathogenesis of several infectious and non-infectious inflammatory CNS disease states, including multiple sclerosis (MS) and its animal model, experimental allergic encephalomyelitis (EAE). An increase in proinflammatory chemokines has been associated with demyelinating lesions and clinical neurological dysfunction in patients with MS; these chemokines could be potential targets for MS therapy. Besides a clearly defined role in mediating leukocyte migration, these and other chemokines may act as immunoregulatory molecules in the driving to Th1/Th2 responses, switch of cytokine profiles, and the induction of tolerance. Since chemokine receptors have now been identified on macrophages, Microglia, astrocytes, and endothelial cells as well as neurons in the CNS, chemokine/receptor interactions may mediate functional responses in a variety of CNS cell types during the course of inflammatory disease states. Therefore, clarification of the roles of chemokines and their receptors in the pathogenesis of EAE and MS will be useful in establishing immunotherapeutic strategies for these neurological autoimmune disorders

196. Zujovic V, Benavides J, Vige X, Carter C, Taupin V (2000) Fractalkine modulates TNF-alpha secretion and neurotoxicity induced by Microglial activation. Glia 29:305-315
     Abstract: Among the chemokine family, fractalkine shows unusual properties: it exists as a membrane-bound and soluble protein, and both fractalkine and its receptor CX(3)CR1 are expressed predominantly in the central nervous system. In rat cell culture models, the chemokine fractalkine was expressed in neurons and Microglia, but not in astrocytes and its receptor exclusively localized to Microglial cells, where its expression was downregulated by treatment with the bacterial endotoxin (LPS). In Microglial cultures, LPS (10 ng/ml) induced a marked increase in the release of the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha). The effects of LPS on TNF-alpha secretion were partially blocked (30%) by fractalkine and the effects of fractalkine were reversed by a polyclonal anti-fractalkine antibody. When Microglial-associated fractalkine was neutralized by anti-fractalkine antibody, the LPS response was increased by 80%, suggesting tonic activation of Microglial fractalkine receptors by endogenous fractalkine. The effects of the antibody were antagonized by the addition of fractalkine. LPS-activated Microglia were neurotoxic when added to neuronal hippocampal culture, producing 20% neuronal death, as measured by NeuN-positive cell counting. An anti-fractalkine antibody produced neurotoxic effects of similar magnitude in this co-culture system and also markedly potentiated the neurotoxic effects of LPS-activated Microglia (40% neuronal death). These results suggest that endogenous fractalkine might act tonically as an anti-inflammatory chemokine in cerebral tissue through its ability to control and suppress certain aspects of Microglial activation. These data may have relevance to degenerative conditions such as multiple sclerosis, in which cerebral inflammatory processes may be activated

197. Balashov KE, Rottman JB, Weiner HL, Hancock WW (1999) CCR5(+) and CXCR3(+) T cells are increased in multiple sclerosis and their ligands MIP-1alpha and IP-10 are expressed in demyelinating brain lesions. Proc.Natl.Acad.Sci.U.S.A 96:6873-6878
     Abstract: multiple sclerosis (MS) is a T cell-dependent chronic inflammatory disease of the central nervous system. The role of chemokines in MS and its different stages is uncertain. Recent data suggest a bias in expression of chemokine receptors by Th1 vs. Th2 cells; human Th1 clones express CXCR3 and CCR5 and Th2 clones express CCR3 and CCR4. Chemokine receptors expressed by Th1 cells may be important in MS, as increased interferon-gamma (IFN-gamma) precedes clinical attacks, and IFN-gamma injection induces disease exacerbations. We found CXCR3(+) T cells increased in blood of relapsing-remitting MS, and both CCR5(+) and CXCR3(+) T cells increased in progressive MS compared with controls. Furthermore, peripheral blood CCR5(+) T cells secreted high levels of IFN-gamma. In the brain, the CCR5 ligand, MIP-1alpha, was strongly associated with Microglia/macrophages, and the CXCR3 ligand, IP-10, was expressed by astrocytes in MS lesions but not unaffected white matter of control or MS subjects. Areas of plaque formation were infiltrated by CCR5-expressing and, to a lesser extent, CXCR3-expressing cells; Interleukin (IL)-18 and IFN-gamma were expressed in demyelinating lesions. No leukocyte expression of CCR3, CCR4, or six other chemokines, or anti-inflammatory cytokines IL-5, IL-10, IL-13, and transforming growth factor-beta was observed. Thus, chemokine receptor expression may be used for immunologic staging of MS and potentially for other chronic autoimmune/inflammatory processes such as rheumatoid arthritis, autoimmune diabetes, or chronic transplant rejection. Furthermore, these results provide a rationale for the use of agents that block CCR5 and/or CXCR3 as a therapeutic approach in the treatment of MS

198. Becher B, Blain M, Giacomini PS, Antel JP (1999) Inhibition of Th1 polarization by soluble TNF receptor is dependent on antigen-presenting cell-derived IL-12. J.Immunol. 162:684-688
     Abstract: Th1-polarized CD4+ T cells are considered central to the development of a number of target-directed autoimmune disorders including multiple sclerosis. The APC-derived cytokine IL-12 is a potent inducer of Th1 polarization in T cells. Inhibition of IL-12 in vivo blocks the development of experimental allergic encephalomyelitis, the animal model for multiple sclerosis. Based on previous work that suggests that the production of IL-12 by activated human central nervous system-derived Microglia is regulated by autocrine TNF-alpha, we wanted to determine whether inhibition of TNF could induce a reduction of Th1 responses by its impact on systemic APCs. We found that soluble TNFR p75-IgG fusion protein (TNFR:Fc) inhibited production of IFN-gamma by allo-Ag-activated blood-derived human CD4 T cells. We documented reduced IL-12 p70 production by APCs in the MLR. By adding back recombinant IL-12, we could rescue IFN-gamma production, indicating that TNFR:Fc acts on APC-derived IL-12. Consistent with an inhibition of the Th1 polarization, we found a decreased expression of IL-12R-beta2 subunit on the T cells. Furthermore, the capacity of T cells to secrete IFN-gamma upon restimulation when previously treated with TNFR:Fc is impaired, whereas IL-2 secretion was not altered. Our results define a TNF-dependent cytokine network that favors development of Th1 immune responses

199. Bonetti B, Stegagno C, Cannella B, Rizzuto N, Moretto G, Raine CS (1999) Activation of NF-kappaB and c-jun transcription factors in multiple sclerosis lesions. Implications for oligodendrocyte pathology. Am.J.Pathol. 155:1433-1438
     Abstract: Oligodendrocytes are a major target of the purported autoimmune response in multiple sclerosis (MS) lesions, but little is known about the mechanisms underlying their demise. Despite the expression of proapoptotic receptors, these cells are rarely seen to undergo apoptosis in situ. On the other hand, cytotoxic mediators present in MS lesions, such as tumor necrosis factor-alpha, are known to generate survival signals through the activation of the transcription factors NF-kappaB and c-jun. The aim of this study was to investigate in chronic active and silent MS lesions and control white matter the expression of c-jun, its activating molecule, JNK, as well as NF-kappaB complex and its inhibitor, IkappaB. By immunohistochemistry we found negligible reactivity for these molecules in control white matter and silent MS plaques. In active MS lesions, double-label immunohistochemistry with oligodendrocyte markers showed up-regulation of the nuclear staining for both NF-kappaB and JNK on a large proportion of oligodendrocytes located at the edge of active lesions and on Microglia/macrophages throughout plaques. Oligodendrocytes showed no reactivity for IkappaB, which was predominantly confined to the cytoplasm of Microglia/macrophages. We hypothesize that activation of these transcriptional pathways may be one mechanism accounting for the paucity of oligodendrocyte apoptosis reported in MS

200. Cannella B, Pitt D, Marchionni M, Raine CS (1999) Neuregulin and erbB receptor expression in normal and diseased human white matter. J.Neuroimmunol. 100:233-242
     Abstract: Human white matter from non-neurologic cases, multiple sclerosis (MS) and other neurologic diseases (OND, inflammatory and non-inflammatory), was subjected to immunocytochemistry and Western blotting for expression of the neuregulin, glial growth factor-2 (GGF2), and its receptors, erbB2, erbB3 and erbB4. GGF2 has previously been shown to have mitogenic effects upon oligodendrocytes in vitro and an enhancing effect upon remyelination in animals with autoimmune demyelination. In all types of human white matter examined, expression of the ligand GGF2 and its three receptors was consistently found on oligodendrocytes, with higher levels being seen in cases of MS. Expression was also seen, albeit at lower levels, on astrocytes and Microglial cells, the latter most commonly in MS and OND. In human lymph node tissue, some lymphocytes were positive for erbB2, erbB3 and erbB4. Western blots confirmed the presence of all three receptors in normal, MS and OND white matter. GGF2 and erbB receptor expression did not correlate with areas of remyelination and reactivity occurred throughout the tissue, with some increase in intensity at the edge of MS lesions. Examination of precursor oligodendrocyte immunoreactivity (with anti-PDGF-Ralpha and NG2), revealed widespread expression throughout both normal and diseased white matter. The presence of GGF2 and its receptors on oligodendrocytes and lymphocytes render this cell type a candidate for functional signaling via this pathway, perhaps in relationship to myelinating activity

201. Carson MJ, Sutcliffe JG, Campbell IL (1999) Microglia stimulate naive T-cell differentiation without stimulating T-cell proliferation. J.Neurosci.Res. 55:127-134
     Abstract: A major question relevant to the initiation and progression of inflammation and autoimmune processes within the central nervous system (CNS) is whether resident Microglia or only infiltrating macrophage can productively interact with T-cells that enter the CNS either actively through extravasation or passively through defects in the blood brain barrier (BBB). We isolated Microglia and macrophage from the brains of healthy adult mice and transgenic mice that displayed many features of multiple sclerosis and HIV leukoencephalopathy due to the astrocytic expression of interleukin (IL)-3 and compared their antigen-presenting cell (APC) functions. We found that unactivated Microglia isolated from healthy nontransgenic mice and activated Microglia isolated from transgenic siblings are relatively weak stimulators of naive T-cell proliferation compared to macrophage populations. The APC function of activated, but not unactivated, Microglia could be increased by treatment acutely with lipopolysaccharide (LPS)/interferon gamma (IFN-gamma). However, this treatment also induced the apparent production of prostaglandins, which reduced T-cell proliferation when indomethacin was absent from the assay cultures. Strikingly, even in the absence of stimulated T-cell proliferation, both unactivated and activated Microglia stimulated the differentiation of naive T-cells into Th1 effector cells, although neither Microglial population was a more effective inducer than macrophages or splenic APCs. Thus, while Microglia are clearly capable of productively interacting with naive T-cells, macrophages have a more robust APC function

202. Cross AK, Woodroofe MN (1999) Chemokines induce migration and changes in actin polymerization in adult rat brain Microglia and a human fetal Microglial cell line in vitro. J.Neurosci.Res. 55:17-23
     Abstract: Microglia, the resident macrophages of the central nervous system, are the primary cells to respond to injury in the brain, both in inflammation, e.g., in multiple sclerosis, and trauma. Chemokines are potential mediators of Microglial cell recruitment to sites of injury; thus, the ability of Microglia to migrate in response to a number of chemokines was assessed. The chemokines monocyte chemoattractant protein 1, macrophage inflammatory protein 1alpha, macrophage inflammatory protein 1beta, RANTES (regulated upon activation normal T cell expressed and secreted), interleukin 8, and IP-10 (interferon gamma inducible protein-10), induce migration and changes in the distribution of f-actin in adult rat Microglia and a human Microglial cell line, CHME3, in vitro. Both cell types show a significant migration response, above control levels, to all the chemokines tested in a typical dose-dependent manner. These chemokines also induced a reorganization of the actin cytoskeleton of the cells. This study indicates that chemokines play an important role in the recruitment of Microglia to areas of central nervous system inflammation

203. Cross AK, Woodroofe MN (1999) Chemokine modulation of matrix metalloproteinase and TIMP production in adult rat brain Microglia and a human Microglial cell line in vitro. Glia 28:183-189
     Abstract: Matrix metalloproteinases (MMPs) are a family of zinc-dependent enzymes, capable of degrading proteins found in the extracellular matrix. MMPs 2 and 9 are known to be produced by Microglia, the resident macrophages of the central nervous system. The control of the secretion of these proteases and the activation of proenzymes by other proteases such as plasmin, as well as the balance between MMP secretion and the secretion of their natural inhibitors (TIMPs), have an important relevance in the pathogenesis of multiple sclerosis (MS). The in vitro control of MMPs 2 and 9, TIMPs 1 and 2, and urokinase-type plasminogen activator by Microglia was examined in response to a panel of chemokines (chemotactic cytokines), using ELISA and zymography techniques. The chemokines MCP1, MIP1beta, RANTES, IL-8, and Fractalkine were all found significantly to increase the secretion of MMPs and TIMPs by a human foetal Microglial cell line, CHME3, after 24 h stimulation. The chemokines tested, MCP1, MIP1beta, and Fractalkine, were also shown to increase MMP9 secretion by primary isolated rat brain Microglia in vitro. MCP1, MIP1alpha/beta, and RANTES significantly decreased the secretion of uPA into culture supernatants in ELISA experiments. These findings suggest an important potential role for the involvement of chemokines in the breakdown of the blood-brain barrier and also the destruction of myelin basic protein in MS

204. De Groot CJ, Montagne L, Barten AD, Sminia P, van d, V (1999) Expression of transforming growth factor (TGF)-beta1, -beta2, and -beta3 isoforms and TGF-beta type I and type II receptors in multiple sclerosis lesions and human adult astrocyte cultures. J.Neuropathol.Exp.Neurol. 58:174-187
     Abstract: It is known that the pleiotropic cytokine transforming growth factor beta (TGF-beta) has a regulatory role in the process of tissue repair and remodelling following injury. As reports on these molecules in multiple sclerosis (MS) lesion with different lesional activity are rare, we studied the cellular localization of TGF-beta1, -beta2, and -beta3 isoforms, and TGF-beta receptor type I (TGF-betaR-I) and TGF-betaR-II expression by immunohistochemistry on postmortem brain tissue from MS and normal control cases. To validate the TGF-beta staining results we demonstrated that cultured human adult astrocytes that produce biological active TGF-beta2, and to a lesser extent TGF-beta1, were immunoreactive for all 3 TGF-beta isoforms. Moreover, at mRNA level TGF-beta1 was detected in MS and normal control brain tissue. In normal control brain tissue, TGF-beta isoforms were expressed in ramified Microglia and TGF-beta2, and -beta3 on neuronal cells in the gray matter TGF-betaR-I and TGF-betaR-II expression was found on endothelial cells, astrocytes, Microglia, and neurons. In active demyelinating MS lesions a strong to intense immunoreactivity was detected for all 3 TGF-beta isoforms in perivascular and parenchymal (foamy) macrophages and in hypertrophic astrocytes. Strong immunoreactivity for TGF-betaR-I and TGF-betaR-II was found on macrophages in both parenchymal and perivascular areas and on hypertrophic astrocytes and endothelial cells in active demyelinating MS lesions. In chronic active and inactive MS lesions, all 3 TGF-beta isoforms and their receptors were strongly expressed in hypertrophic astrocytes. Our findings strongly suggest that the expression of the various TGF-beta isoforms and their receptor types found in MS lesions with different cellular activity participate in reactive processes leading to the formation of chronic MS lesions

205. De Keyser J, Wilczak N, Leta R, Streetland C (1999) Astrocytes in multiple sclerosis lack beta-2 adrenergic receptors. Neurology 53:1628-1633
     Abstract: BACKGROUND: In MS, T cells reactive to myelin proteins can cross the blood-brain barrier and release proinflammatory cytokines, such as interferon gamma. These can induce glial cells to express class II major histocompatibility complex (MHC) molecules, which are required to present myelin antigens to the T cells in order to mount a proper autoimmune response. Both Microglia and astrocytes can function as antigen-presenting cells. In contrast to Microglia, endogenous suppressors, including norepinephrine, regulate astrocytic class II MHC expression. The effects of norepinephrine are mediated through activation of P2 adrenergic receptors. OBJECTIVE: To investigate P, adrenergic receptors in astrocytes in MS. METHODS: Immunocytochemical techniques were applied in postmortem brain tissue from 10 patients with MS, three patients with a cerebral infarction, and six controls, and in spinal cord from three patients with ALS. RESULTS: beta2 adrenergic receptors were visualized on astrocytes in white matter of controls, and they were prominently expressed in reactive astrocytes at the boundary of cerebral infarctions and in the lateral corticospinal tract in ALS. In MS, beta2 adrenergic receptors could neither be visualized on astrocytes in normal-appearing white matter nor in reactive astrocytes in chronic active and inactive plaques, whereas they were normally present on neurons. MHC class II-positive astrocytes were only visualized in chronic active plaques. CONCLUSIONS: Because astrocytic beta2 adrenergic receptors are involved in suppressing inducibility of MHC class II molecules, we suggest that their lack of expression may play an important role in the induction or perpetuation of autoimmune reactions in MS

206. Di Bello IC, Dawson MR, Levine JM, Reynolds R (1999) Generation of oligodendroglial progenitors in acute inflammatory demyelinating lesions of the rat brain stem is associated with demyelination rather than inflammation. J.Neurocytol. 28:365-381
     Abstract: Remyelination is an extremely efficient process in the adult rodent central nervous system yet the source of new oligodendroglia that appear following primary demyelination is still subject to much debate. Using a reliable marker for oligodendroglial progenitor cells in vivo, the NG2 chondroitin sulphate proteoglycan, we have evaluated the response of endogenous NG2(+) cells in the adult rat brain stem and cerebellum to inflammatory demyelinating lesions in an experimentally induced animal model of multiple sclerosis (MS), antibody augmented experimental allergic encephalomyelitis (ADEAE). We have manipulated T-cell mediated EAE in Lewis rats by injecting in addition, either anti-myelin/oligodendroglial glycoprotein (MOG) antibodies to induce inflammatory demyelination, or non-specific mouse immunoglobulins to induce an inflammatory response without demyelination. We have examined the relationship of NG2(+) progenitor cells to Microglia (OX-42(+)), astrocytes (GFAP(+)) and mature oligodendroglia (CNP(+)), in the normal and demyelinated CNS. In the normal CNS NG2-expressing cells are closely intermingled with other glia but represent a distinct cell population. A prominent inflammatory response, identified by the presence of large perivascular and periventricular accumulations of reactive OX42(+) macrophages/Microglia, occurred in animals with ADEAE at 7-9 days post injection (DPI), coinciding with severe clinical symptoms. In animals injected with anti-MOG antibodies inflammation was followed by the appearance of large areas of demyelination at 11-14 DPI, at which point the animals had recovered clinically. The response of NG2(+) cells was different depending on whether the inflammation was accompanied by demyelination. In the presence of inflammation, NG2(+) cells responded by an increase in immunoreactivity and an alteration in their morphology, exhibiting enlarged cell bodies and an increased number of intensely stained processes. In areas of demyelination NG2(+) cells had fewer intensely stained processes reminiscent of progenitor cells seen during development. Quantitative analysis revealed a 3-fold increase in the number of NG2(+) cells in demyelinated lesions at 11 DPI, whereas no change was observed in areas of inflammation in the absence of demyelination. Mitotic figures were only seen in NG2(+) cells in areas of demyelination. NG2(+) cell numbers appeared to return to control levels following remyelination. These results suggest that endogenous oligodendroglial progenitors divide and/or migrate, in response to signals triggered by demyelinating rather than inflammatory events, to generate a large progenitor population sufficient to promote the rapid and successful remyelination observed in this model

207. Dowling P, Ming X, Raval S, Husar W, Casaccia-Bonnefil P, Chao M, Cook S, Blumberg B (1999) Up-regulated p75NTR neurotrophin receptor on glial cells in MS plaques. Neurology 53:1676-1682
     Abstract: OBJECTIVE: To investigate the expression of the neurotrophin receptor p75NTR on glial cells within MS plaques. BACKGROUND: In recent studies on the pathogenesis of MS white matter plaques, we found large populations of inflammatory and resident glial cells, including oligodendrocytes undergoing cell death, and identified increased expression of Fas receptor and ligand death pathway signaling molecules on the same glial cell types. In another study, the p75NTR was shown to induce apoptotic death of maturing oligodendrocytes when exposed to NGF in vitro. METHODS: We used immunohistochemistry and in situ reverse-transcription PCR to detect p75NTR expression on inflammatory and resident glial cells in MS plaques and used TUNEL staining for fragmented DNA to detect cell death. RESULTS: Up-regulated p75NTR messenger RNA and protein were demonstrated in both oligodendrocytes and Microglia/macrophages in MS plaques but not in control white matter. However, only a fraction of p75NTR expressing oligodendrocytes was also stained by TUNEL. CONCLUSIONS: Glial cell expression of p75NTR receptor is up-regulated during MS plaque formation. The exact role of this receptor in glial cell death and/or survival in MS remains to be elucidated

208. Fawcett JW, Asher RA (1999) The glial scar and central nervous system repair. Brain Res.Bull. 49:377-391
     Abstract: Damage to the central nervous system (CNS) results in a glial reaction, leading eventually to the formation of a glial scar. In this environment, axon regeneration fails, and remyelination may also be unsuccessful. The glial reaction to injury recruits Microglia, oligodendrocyte precursors, meningeal cells, astrocytes and stem cells. Damaged CNS also contains oligodendrocytes and myelin debris. Most of these cell types produce molecules that have been shown to be inhibitory to axon regeneration. Oligodendrocytes produce NI250, myelin-associated glycoprotein (MAG), and tenascin-R, oligodendrocyte precursors produce NG2 DSD-1/phosphacan and versican, astrocytes produce tenascin, brevican, and neurocan, and can be stimulated to produce NG2, meningeal cells produce NG2 and other proteoglycans, and activated Microglia produce free radicals, nitric oxide, and arachidonic acid derivatives. Many of these molecules must participate in rendering the damaged CNS inhibitory for axon regeneration. Demyelinated plaques in multiple sclerosis consists mostly of scar-type astrocytes and naked axons. The extent to which the astrocytosis is responsible for blocking remyelination is not established, but astrocytes inhibit the migration of both oligodendrocyte precursors and Schwann cells which must restrict their access to demyelinated axons

209. Gonzalez-Scarano F, Baltuch G (1999) Microglia as mediators of inflammatory and degenerative diseases. Annu.Rev.Neurosci. 22:219-240
     Abstract: Microglia are the principal immune cells in the central nervous system (CNS) and have a critical role in host defense against invading microorganisms and neoplastic cells. However, as with immune cells in other organs, Microglia may play a dual role, amplifying the effects of inflammation and mediating cellular degeneration as well as protecting the CNS. In entities like human immunodeficiency virus (HIV) infection of the nervous system, Microglia are also critical to viral persistence. In this review we discuss the role of Microglia in three diseases in which their activity is at least partially deleterious: HIV, multiple sclerosis, and Alzheimer's disease

210. Gveric D, Cuzner ML, Newcombe J (1999) Insulin-like growth factors and binding proteins in multiple sclerosis plaques. Neuropathol.Appl.Neurobiol. 25:215-225
     Abstract: Insulin-like growth factors (IGFs) play an important role in development and myelination in the central nervous system (CNS) as well as in the proliferation and differentiation of cells of the immune system. To assess the influence of this growth factor family on demyelination and repair in multiple sclerosis (MS), the expression of IGF-I, IGF-II, insulin, IGF binding proteins (IGFBP) 1-3 and IGF-I receptor (IGF-IR) in CNS tissue from MS and normal control cases was studied by immunocytochemistry. In active MS lesions, the expression of IGF-I, insulin and IGFBP1 was detected in hypertrophic astrocytes while that of IGF-II and IGFBP2 and 3 was confined to foamy macrophages within lesions and activated Microglia in adjacent white matter. IGF-IR, the major IGF receptor, was immunolocalized in macrophages and an astrocyte subpopulation in plaques. Oligodendrocytes in normal-appearing white matter expressed only IGFBP1, not IGFs or IGF-IR. As the remyelinating capacity of oligodendrocytes could be impaired owing to the absence of IGF-IR, the prevailing role of IGFs in inflammatory demyelination may be to promote phagocytosis of myelin and astrogliosis

211. Hafler DA (1999) The distinction blurs between an autoimmune versus microbial hypothesis in multiple sclerosis. J.Clin.Invest 104:527-529

212. Hesselgesser J, Horuk R (1999) Chemokine and chemokine receptor expression in the central nervous system. J.Neurovirol. 5:13-26
     Abstract: A decade ago several new cytokines were described that orchestrated the activation and migration of immune cells. These newly described cytokines, of which interleukin-8 (IL-8) was a representative member, defined a novel group of molecules called chemokines (chemotactic cytokines). Chemokines are low molecular weight, 8-12 kDa, basic proteins that have been classified into four distinct families, CXC, CC, C and CX3C, based on the position of their first two conserved cysteine residues. The expression and biological function of chemokines along with their cognate receptors have been well described on various subsets of leukocytes. Only more recently have these molecules been described on various cells within the central nervous system. These pro-inflammatory proteins have been implicated in a variety of diseases within the central nervous system from multiple sclerosis to AIDS dementia. While chemokines are likely to enhance the evolution of central nervous system inflammatory disorders they also have other roles in normal brain function and development. This review summarizes the role of chemokines and their receptors in the normal and pathophysiological brain

213. Hickey WF (1999) The pathology of multiple sclerosis: a historical perspective. J.Neuroimmunol. 98:37-44
     Abstract: In the century and a half since multiple sclerosis (MS) was first recognized, the pathology of the condition has been defined with increasing detail. From the recognition and definition of MS as a clinical phenomenon, studies of the diseased brain tissue have progressed in a manner dependent on the science of the time. Through multiple generations, the increasingly detailed analysis of the MS lesion itself has lead to an increasingly sophisticated understanding of a complex, apparently diverse, immunopathological process. During this evolution, many hypotheses concerning the pathogenesis of MS have been overturned, and the interpretation of some clearly delineated gross and histological findings have been reversed. This review plots the progress and highlights current theories and emerging concepts regarding one of the most enigmatic of neurological diseases

214. Howard LM, Miga AJ, Vanderlugt CL, Dal Canto MC, Laman JD, Noelle RJ, Miller SD (1999) Mechanisms of immunotherapeutic intervention by anti-CD40L (CD154) antibody in an animal model of multiple sclerosis. J.Clin.Invest 103:281-290
     Abstract: Relapsing experimental autoimmune encephalomyelitis (R-EAE) in the SJL mouse is a Th1-mediated autoimmune demyelinating disease model for human multiple sclerosis and is characterized by infiltration of the central nervous system (CNS) by Th1 cells and macrophages. Disease relapses are mediated by T cells specific for endogenous myelin epitopes released during acute disease, reflecting a critical role for epitope spreading in the perpetuation of chronic central CNS pathology. We asked whether blockade of the CD40-CD154 (CD40L) costimulatory pathway could suppress relapses in mice with established R-EAE. Anti-CD154 antibody treatment at either the peak of acute disease or during remission effectively blocked clinical disease progression and CNS inflammation. This treatment blocked Th1 differentiation and effector function rather than expansion of myelin-specific T cells. Although T-cell proliferation and production of interleukin (IL)-2, IL-4, IL-5, and IL-10 were normal, antibody treatment severely inhibited interferon-gamma production, myelin peptide-specific delayed-type hypersensitivity responses, and induction of encephalitogenic effector cells. Anti-CD154 antibody treatment also impaired the expression of clinical disease in adoptive recipients of encephalitogenic T cells, suggesting that CD40-CD154 interactions may be involved in directing the CNS migration of these cells and/or in their effector ability to activate CNS macrophages/Microglia. Thus, blockade of CD154-CD40 interactions is a promising immunotherapeutic strategy for treatment of ongoing T cell-mediated autoimmune diseases

215. Jiang H, Bielekova B, Okazaki H, Clarence-Smith K, Johnson KP, Bergey G, Martin R, Dhib-Jalbut S (1999) The effect of vesnarinone on TNF alpha production in human peripheral blood mononuclear cells and Microglia: a preclinical study for the treatment of multiple sclerosis. J.Neuroimmunol. 97:134-145
     Abstract: Vesnarinone (OPC-8212) is a synthetic quinolinone derivative with inotropic and immunomodulatory effects. Vesnarinone has been shown to inhibit tumor necrosis factor-alpha (TNF alpha) produced by mitogen stimulated macrophages, and to inhibit phosphodiesterase (PDE) type III in cardiac muscle. TNF alpha and interferon-gamma (IFNgamma) have been implicated in the pathogenesis of autoimmune diseases, and both cytokines are targets for therapeutic intervention. IFNgamma can enhance autoimmune disease through direct effects, and indirectly by priming macrophages to produce TNF alpha. In this study, we demonstrate that while vesnarinone enhances basal TNF alpha levels, it inhibits TNF alpha production in peripheral blood mononuclear cells from multiple sclerosis (MS) patients and healthy donors stimulated with lipopolysaccharide (LPS) or primed with IFNgamma and stimulated with suboptimal doses of LPS. In addition, vesnarinone inhibited TNF alpha production in primary adult human Microglial cultures. However, in contrast to rolipram, another TNF alpha inhibiting agent, vesnarinone failed to inhibit TNF alpha production by myelin basic protein specific T-cell lines. As oral TNF inhibitors are currently being considered in the USA for clinical application in MS, the implications of our findings on the development of vesnarinone for treatment of MS are discussed

216. Katz-Levy Y, Neville KL, Girvin AM, Vanderlugt CL, Pope JG, Tan LJ, Miller SD (1999) Endogenous presentation of self myelin epitopes by CNS-resident APCs in Theiler's virus-infected mice. J.Clin.Invest 104:599-610
     Abstract: The mechanisms underlying the initiation of virus-induced autoimmune disease are not well understood. Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD), a mouse model of multiple sclerosis, is initiated by TMEV-specific CD4(+) T cells targeting virally infected central nervous system-resident (CNS-resident) antigen-presenting cells (APCs), leading to chronic activation of myelin epitope-specific CD4(+) T cells via epitope spreading. Here we show that F4/80(+), I-A(s+), CD45(+) macrophages/Microglia isolated from the CNS of TMEV-infected SJL mice have the ability to endogenously process and present virus epitopes at both acute and chronic stages of the disease. Relevant to the initiation of virus-induced autoimmune disease, only CNS APCs isolated from TMEV-infected mice with preexisting myelin damage, not those isolated from naive mice or mice with acute disease, were able to endogenously present a variety of proteolipid protein epitopes to specific Th1 lines. These results offer a mechanism by which localized virus-induced, T cell-mediated inflammatory myelin destruction leads to the recruitment/activation of CNS-resident APCs that can process and present endogenous self epitopes to autoantigen-specific T cells, and thus provide a mechanistic basis by which epitope spreading occurs

217. Lake J, Weller RO, Phillips MJ, Needham M (1999) Lymphocyte targeting of the brain in adoptive transfer cryolesion-EAE. J.Pathol. 187:259-265
     Abstract: Lymphocyte infiltration and Microglial activation in experimental autoimmune encephalomyelitis (EAE) are mainly centred on the spinal cord. However, a cryolesion to one cerebral hemisphere (cryolesion-EAE) induces six-fold enhancement of EAE in the cerebral hemispheres and removal of the cervical lymph nodes reduces such enhancement by 40 per cent. This study tests the hypothesis that lymphocytes from donor rats with cryolesion-EAE will selectively target the brain rather than the spinal cord when transferred to naive recipients. Acute EAE was induced in 15 Lewis rats (donors); ten donors received a cryolesion to the left cerebral hemisphere 8 days post-inoculation of antigen and adjuvant. Five rats with EAE received no cryolesion. Lymphocytes from cryolesion-EAE donors or from EAE-only donors were cultured for 72 h in medium containing myelin basic protein and then injected into a total of 21 naive recipients, which were killed 8 days later. The severity of EAE in brains and spinal cords was assessed in immunocytochemically stained sections by quantifying the number of vessels showing lymphocyte cuffs (W3/13 antibody) and the level of MHC class II antigen expression by Microglia (OX6 antibody). When compared with recipients of EAE-only donor lymphocytes, the severity of cerebral EAE was increased 2- to 2.6-fold in the recipients of crylesion-EAE donor lymphocytes (p < 0.01); EAE in the spinal cord was reduced. These results suggest that lymphocytes from cryolesion-EAE donors preferentially target the brain in recipient animals in preference to the spinal cord. By analogy with cryolesion-EAE, focal central nervous system (CNS) damage with drainage of auto-antigens to regional lymph nodes in man may play a role in determining the site and timing of initial and recurrent multiple sclerosis lesions

218. Lavi E, Das SJ, Weiss SR (1999) Cellular reservoirs for coronavirus infection of the brain in beta2-microglobulin knockout mice. Pathobiology 67:75-83
     Abstract: Mouse hepatitis virus (MHV) A59 infection which causes acute encephalitis, hepatitis, and chronic demyelination, is one of the experimental models for multiple sclerosis. Previous studies showed that lethal infection of beta2-microglobulin 'knockout' (beta2M(-/-)) mice required 500-fold less virus and viral clearance was delayed as compared to infection of immunocompetent C57Bl/6 (B6) mice. To investigate the mechanism of the increased susceptibility of beta2M(-/-) mice to MHV-A59, we studied organ pathology and the distribution of viral antigen and RNA during acute and chronic infection. A59-infected beta2M(-/-) mice were more susceptible to acute encephalitis and hepatitis, but did not have increased susceptibility to demyelination. Viral antigen and RNA distribution in the brain was increased in Microglia, lymphocytes, and small vessel endothelial cells while the distribution in neurons and glia was similar in beta2M(-/-) mice and B6 mice. Acute hepatitis and thymus cortical hypoplasia in beta2M(-/-) mice were delayed in onset but pathologic changes in these organs were similar to those in B6 mice. The low rate of demyelination in beta2M(-/-) mice was consistent with the low dose of the virus given. A less neurotropic virus MHV-2, caused increased parenchymal inflammation in beta2M(-/-) mice, but without demyelination. Thus, CD8+ cells were important for viral clearance from endothelial cells, Microglia and inflammatory cells, but not from neuronal and glial cells. In addition, CD8+ cells played a role in preventing the spread of encephalitis

219. Lee SJ, Benveniste EN (1999) Adhesion molecule expression and regulation on cells of the central nervous system. J.Neuroimmunol. 98:77-88
     Abstract: Cellular adhesion molecules were initially defined as cell surface structures mediating cell-cell and cell-extracellular matrix (ECM) interactions. Adhesion molecules involved in immune responses have been classified into three families according to their structure: selectins, immunoglobulin (Ig) superfamily, and integrins. It has been well documented that adhesion molecules of these family members (E-selectin, ICAM-1, and VCAM-1) are expressed on brain microvessel endothelial cells in active lesions of multiple sclerosis (MS) brain. In addition, accumulating data show that glial cells can express some of these adhesion molecules upon activation: astrocytes can express ICAM-1, VCAM-1, and E-selectin, and Microglia express ICAM-1 and VCAM-1. In vitro studies show that these adhesion molecules are actively regulated by several cytokines which have relevance to MS or experimental autoimmune encephalomyelitis (EAE). In addition, soluble forms of adhesion molecules have been found in the serum and cerebrospinal fluid (CSF) of MS patients, and may be useful diagnostically. Experimental therapy of EAE using antibodies against several adhesion molecules clearly shows that adhesion molecules are critical for the pathogenesis of EAE. Thus far, the function of adhesion molecule expression on brain endothelial and glial cells has not been clearly elucidated. Studies on the possible role of adhesion molecules on brain endothelial and glial cells will be helpful in understanding their involvement in immune responses in the central nervous system (CNS)

220. Parra B, Hinton DR, Marten NW, Bergmann CC, Lin MT, Yang CS, Stohlman SA (1999) IFN-gamma is required for viral clearance from central nervous system oligodendroglia. J.Immunol. 162:1641-1647
     Abstract: Infection of the central nervous system (CNS) by the JHM strain of mouse hepatitis virus (JHMV) is a rodent model of the human demyelinating disease multiple sclerosis. The inability of effective host immune responses to eliminate virus from the CNS results in a chronic infection associated with ongoing recurrent demyelination. JHMV infects a variety of CNS cell types during the acute phase of infection including ependymal cells, astrocytes, Microglia, oligodendroglia, and rarely in neurons. Replication within the majority of CNS cell types is controlled by perforin-dependent virus-specific CTL. However, inhibition of viral replication in oligodendroglia occurs via a perforin-independent mechanism(s). The potential role for IFN-gamma as mediator controlling JHMV replication in oligodendroglia was examined in mice deficient in IFN-gamma secretion (IFN-gamma0/0 mice). IFN-gamma0/0 mice exhibited increased clinical symptoms and mortality associated with persistent virus, demonstrating an inability to control replication. Neither antiviral Ab nor CTL responses were diminished in the absence of IFN-gamma, although increased IgG1 was detected in IFN-gamma0/0 mice. Increased virus Ag in the absence of IFN-gamma localized almost exclusively to oligodendroglia and was associated with increased CD8+ T cells localized within white matter. These data suggest that although perforin-dependent CTL control virus replication within astrocytes and Microglia, which constitute the majority of infected CNS cells, IFN-gamma is critical for control of viral replication in oligodendroglia. Therefore, different mechanisms are used by the host defenses to control virus replication within the CNS, dependent upon the phenotype of the targets of virus replication

221. Persidsky Y (1999) Model systems for studies of leukocyte migration across the blood - brain barrier. J.Neurovirol. 5:579-590
     Abstract: The blood - brain barrier (BBB) plays a crucial role in central nervous system (CNS) homeostasis. Serving as the brain's protective shield it regulates soluble factor and cellular exchanges from blood to brain. Critical to its function, the BBB is composed of brain microvascular endothelial cells (BMVEC), a collagen matrix, and astrocytes. Astrocytic endfeet surround the BMVEC abluminal surface and influence the 'tightness' and trafficking role of the barrier. In neurodegenerative disorders (for example stroke, multiple sclerosis and HIV encephalitis) the BBB becomes compromised. This is, in part, immune mediated. An accumulating body of evidence demonstrates that the cellular components of the BBB are themselves immunocompetent. Perivascular cells (astrocytes, macrophages and Microglial cells) and BMVEC produce inflammatory factors that affect BBB permeability and expression of adhesion molecules. These affect cell trafficking into the CNS. Leukocyte BBB migration can be influenced by cytokines and chemokines produced by glia. Astrocytes and macrophages secrete a multitude of factors that affect brain immune responses. Interactions between BMVEC, leukocytes and/or glia, immunological activation and noxious (infectious, toxic and immune-mediated) brain insults all appear to play important roles in this BBB cell trafficking. New information gained into the mechanisms of leukocyte-brain penetration may provide novel insights in the pathogenesis and treatment strategies of neurodegenerative disorders

222. Phillips LM, Simon PJ, Lampson LA (1999) Site-specific immune regulation in the brain: differential modulation of major histocompatibility complex (MHC) proteins in brainstem vs. hippocampus. J.Comp Neurol. 405:322-333
     Abstract: Although neurotransmitters and neuropeptides are known to affect immune function in vitro and in non-neural tissues, little is known about how the local mix of neurochemicals affects immune function in the brain. Here, we study local modulation of the class II major histocompatibility complex (MHC) proteins, which present antigen to T cells in a key pathway for cell-mediated immune activity. Two sites that are well-separated anatomically and have very different neuroregulatory environments, the brainstem and hippocampus, were compared. The class II-upregulating cytokine, gamma interferon (IFN-gamma, 0.1 to 10,000 U/site), was injected stereotaxically into the hippocampus and contralateral brainstem of adult Charles-derived Fischer rats. Four days later, monoclonal antibody staining was used to detect class II MHC proteins on cryostat sections, followed by computer-assisted image analysis. As compared to hippocampus, the brainstem showed enhanced class II expression at lower IFN-gamma doses, and reached a higher plateau. Site-specific class II modulation was also seen within the layers of the hippocampus, and among other brain sites. Injection of marker protein to visualize the spread of injected protein, plus injection of IFN-gamma into alternative sites, suggested that preferential flow cannot explain all of the site-specific effects. We suggest that the local neuroregulatory environment and/or intrinsic differences among target Microglia are likely to play a role. Implications for the distribution of pathological changes, such as multiple sclerosis plaques, and for local immunotherapy are discussed

223. Popko B, Baerwald KD (1999) Oligodendroglial response to the immune cytokine interferon gamma. Neurochem.Res. 24:331-338
     Abstract: In the human demyelinating disorder multiple sclerosis, and its animal model experimental allergic encephalomyelitis, there is a breakdown of the blood-brain barrier and an infiltration of immune cells into the CNS. Infiltrating T lymphocytes and macrophages are believed to be key mediators of the disease process. Considerable circumstantial and experimental evidence has suggested that the pleiotropic cytokine interferon gamma (IFN-gamma), which is exclusively expressed by T cells and natural killer cells, is a deleterious component of the immune response in these disorders. When experimentally introduced into the CNS IFN-gamma promotes many of the pathological changes that occur in immune-mediated demyelinating disorders. In vitro, this cytokine elicits a number of effects on oligodendrocytes, including cell death. The harmful actions of IFN-gamma on CNS myelin are likely mediated through direct effects on the myelinating cells, as well as through the activation of macrophages and Microglia. In this review we summarize relevant studies concerning the action of IFN-gamma in demyelinating disorders and discuss possible mechanisms for the observed effects

224. Reynolds WF, Rhees J, Maciejewski D, Paladino T, Sieburg H, Maki RA, Masliah E (1999) Myeloperoxidase polymorphism is associated with gender specific risk for Alzheimer's disease. Exp.Neurol. 155:31-41
     Abstract: Myeloperoxidase (MPO) is a myeloid-specific enzyme that generates hypochlorous acid and other reactive oxygen species. MPO is present at high levels in circulating neutrophils and monocytes but is not detectable in Microglia, brain-specific macrophages, in normal brain tissue. However, an earlier study indicated that MPO is present in macrophage-Microglia at multiple sclerosis lesions, suggesting that reactivation of MPO gene expression may play a role in neurodegenerative diseases involving macrophage-Microglia. In the present study, MPO is shown to colocalize with amyloid beta (Abeta) in senile plaques in cerebral cortex sections from Alzheimer's disease (AD) brain tissue. Microglia costaining for MPO and CD68 are closely associated with plaques, suggesting that plaque components induce MPO expression in Microglia. In support of this interpretation, treatment of rodent Microglia with aggregated Abeta(1-42) was shown to induce MPO mRNA expression. Also, the ApoE4 allele, the major AD risk factor associated with increased Abeta deposition, was shown to correlate with increased MPO deposition in plaques (P = 0.01, ANOVA). Finally, a genetic polymorphism links MPO expression to Alzheimer's risk, in that a higher expressing SpSp MPO genotype was associated with increased incidence of AD in females, and decreased incidence in males (P = 0.006). These findings suggest that the MPO polymorphism is a gender-specific risk factor for Alzheimer's disease

225. Satoh J, Kurohara K, Yukitake M, Kuroda Y (1999) The 14-3-3 protein detectable in the cerebrospinal fluid of patients with prion-unrelated neurological diseases is expressed constitutively in neurons and glial cells in culture. Eur.Neurol. 41:216-225
     Abstract: The 14-3-3 protein belongs to a family of 30-kD proteins originally identified by two-dimensional analysis of brain protein extracts. Recently, the detection of the 14-3-3 protein in the cerebrospinal fluid (CSF) is utilized as a highly reliable test for the premortem diagnosis of prion diseases such as Creutzfeldt-Jakob disease. For the initial step, to clarify the biological implication of the CSF 14-3-3 protein in these diseases, its expression was investigated in neural tissues and cultures and CSF samples from patients with a variety of neurological diseases by Western blot analysis and immunocytochemistry. The constitutive expression of the 14-3-3 protein was identified in all neural and nonneural tissues examined. It was expressed in all neurons, astrocytes, oligodendrocytes, and Microglia in culture with its location in both cytoplasmic and nuclear regions. The 14-3-3 protein was detected in the CSF of 8 out of 71 patients, including 1 Gerstmann-Straussler-Scheinker disease patient and 7 patients with prion-unrelated neurological diseases, such as meningoencephalitis of viral, bacterial, or tuberculous origin, multiple sclerosis, and mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes. These results suggest that the 14-3-3 protein expressed constitutively at substantial levels in both neurons and glial cells might be released into the CSF as a disease-nonspecific consequence of the extensive brain damage and indicate that the analysis of the 14-3-3 protein in the CSF is not useful as a screening test for prion diseases

226. Smith KJ, Kapoor R, Felts PA (1999) Demyelination: the role of reactive oxygen and nitrogen species. Brain Pathol. 9:69-92
     Abstract: This review summarises the role that reactive oxygen and nitrogen species play in demyelination, such as that occurring in the inflammatory demyelinating disorders multiple sclerosis and Guillain-Barre syndrome. The concentrations of reactive oxygen and nitrogen species (e.g. superoxide, nitric oxide and peroxynitrite) can increase dramatically under conditions such as inflammation, and this can overwhelm the inherent antioxidant defences within lesions. Such oxidative and/or nitrative stress can damage the lipids, proteins and nucleic acids of cells and mitochondria, potentially causing cell death. Oligodendrocytes are more sensitive to oxidative and nitrative stress in vitro than are astrocytes and Microglia, seemingly due to a diminished capacity for antioxidant defence, and the presence of raised risk factors, including a high iron content. Oxidative and nitrative stress might therefore result in vivo in selective oligodendrocyte death, and thereby demyelination. The reactive species may also damage the myelin sheath, promoting its attack by macrophages. Damage can occur directly by lipid peroxidation, and indirectly by the activation of proteases and phospholipase A2. Evidence for the existence of oxidative and nitrative stress within inflammatory demyelinating lesions includes the presence of both lipid and protein peroxides, and nitrotyrosine (a marker for peroxynitrite formation). The neurological deficit resulting from experimental autoimmune demyelinating disease has generally been reduced by trial therapies intended to diminish the concentration of reactive oxygen species. However, therapies aimed at diminishing reactive nitrogen species have had a more variable outcome, sometimes exacerbating disease

227. Smith ME (1999) Phagocytosis of myelin in demyelinative disease: a review. Neurochem.Res. 24:261-268
     Abstract: In the cell-mediated demyelinating diseases such as experimental allergic encephalomyelitis and multiple sclerosis, as well as their peripheral nerve counterparts, the phagocytic cells are the agent of myelin destruction. Both resident Microglia and peripheral macrophages invading the nervous system have been shown to phagocytize myelin, although Microglia appear to be more active, especially at early stages of disease. Several different receptors on these cells have been implicated as myelin receptors, with the Fc- and complement receptors receiving the most attention. Other receptors, especially the macrophage scavenger receptor with its broad specificity deserves further exploration, especially in view of its affinity for phosphatidylserine, which becomes externalized with membrane disruption. Evidence is shown for cytokine regulation of phagocytic activity in both macrophages and Microglia. Further investigation of the pathways of cytokine action on myelin phagocytosis through signal transduction molecules will be important for a further understanding of the events leading to myelin destruction in demyelinating diseases

228. Sorensen TL, Tani M, Jensen J, Pierce V, Lucchinetti C, Folcik VA, Qin S, Rottman J, Sellebjerg F, Strieter RM, Frederiksen JL, Ransohoff RM (1999) Expression of specific chemokines and chemokine receptors in the central nervous system of multiple sclerosis patients. J.Clin.Invest 103:807-815
     Abstract: Chemokines direct tissue invasion by specific leukocyte populations. Thus, chemokines may play a role in multiple sclerosis (MS), an idiopathic disorder in which the central nervous system (CNS) inflammatory reaction is largely restricted to mononuclear phagocytes and T cells. We asked whether specific chemokines were expressed in the CNS during acute demyelinating events by analyzing cerebrospinal fluid (CSF), whose composition reflects the CNS extracellular space. During MS attacks, we found elevated CSF levels of three chemokines that act toward T cells and mononuclear phagocytes: interferon-gamma-inducible protein of 10 kDa (IP-10); monokine induced by interferon-gamma (Mig); and regulated on activation, normal T-cell expressed and secreted (RANTES). We then investigated whether specific chemokine receptors were expressed by infiltrating cells in demyelinating MS brain lesions and in CSF. CXCR3, an IP-10/Mig receptor, was expressed on lymphocytic cells in virtually every perivascular inflammatory infiltrate in active MS lesions. CCR5, a RANTES receptor, was detected on lymphocytic cells, macrophages, and Microglia in actively demyelinating MS brain lesions. Compared with circulating T cells, CSF T cells were significantly enriched for cells expressing CXCR3 or CCR5. Our results imply pathogenic roles for specific chemokine-chemokine receptor interactions in MS and suggest new molecular targets for therapeutic intervention

229. Stanislaus R, Pahan K, Singh AK, Singh I (1999) Amelioration of experimental allergic encephalomyelitis in Lewis rats by lovastatin. Neurosci.Lett. 269:71-74
     Abstract: Proinflammatory cytokines and inducible nitric oxide synthase (iNOS) are involved in the pathogenesis of experimental allergic encephalomyelitis (EAE), an animal model of multiple sclerosis (MS). We have previously reported that lovastatin (Pahan, K., Sheikh., F.G., Namboodiri, A. and Singh, I., Lovastatin and Phenylacetate inhibit the induction of nitric oxide synthase and cytokines in rat primary astrocytes, Microglia and macrophages. J. Clin. Invest., 100 (1997) 2671-2679.), an inhibitor of the mevalonate pathway, inhibits the expression of iNOS and proinflammatory cytokines in rat primary glial cells (astroglia and Microglia) and macrophages. The present study underlines the therapeutic importance of lovastatin in ameliorating the neuroinflammatory disease process in the central nervous system of EAE rats. Immunohistochemical results show a higher degree of expression of iNOS, tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in brains of rats with acute monophasic EAE relative to the control animals. Administration of lovastatin inhibited the expression of iNOS, TNF-alpha and IFN-gamma in the CNS of EAE rats and improved the clinical signs of EAE suggesting that this compound may have therapeutic potential in the treatment of neuroinflammatory diseases like MS

230. Suzumura A, Sawada M (1999) Effects of vesnarinone on cytokine production and activation of murine Microglia. Life Sci. 64:1197-1203
     Abstract: Tumor necrosis factor alpha (TNF alpha) is considered to play a critical role in the development of various pathological processes in the central nervous system (CNS), such as neuronal degeneration, demyelination and gliosis. In order to search for agents which suppress TNF alpha production in the CNS for future treatment of these pathological conditions, the effects of a synthetic oral inotropic agent, vesnarinone, on murine Microglia were examined. Vesnarinone significantly suppressed TNF alpha production by Microglia in a dose-dependent manner, without affecting their viability, enzyme activity or expression of the major histocompatibility complex. Since the reported maximum serum concentration is high enough to suppress TNF alpha production in vitro (about 20 microM) after oral administration of the therapeutic dose of vesnarinone, this drug will be useful to treat intractable neurological diseases such as neurodegenerative disorders, multiple sclerosis or HIV-related neurological disorders

231. Tan J, Town T, Paris D, Placzek A, Parker T, Crawford F, Yu H, Humphrey J, Mullan M (1999) Activation of Microglial cells by the CD40 pathway: relevance to multiple sclerosis. J.Neuroimmunol. 97:77-85
     Abstract: It is well known that Microglial cells perform a key role in mediating inflammatory processes, which are associated with neurodegenerative diseases such as multiple sclerosis (MS). In this study, we report that CD40 expression on Microglia is greatly enhanced by a low dose (10 U/ml) of IFN-gamma. We also find that ligation of Microglial CD40 by CD40L triggers a significant production of TNF-alpha. Activation of Microglia by ligation of CD40 in the presence of IFN-gamma results in cultured cortical neuronal injury, which is markedly attenuated by blockade of the CD40 pathway or neutralization of TNF-alpha. Finally, we find significant levels of IFN-gamma and TNF-alpha in the medium of co-cultured activated CD4+ T cells and Microglial cells, showing that Microglia can supply the CD40 receptor to activated CD4+ T cells and suggesting that this cellular interaction is a key event in MS pathophysiology

232. Torreilles F, Salman-Tabcheh S, Guerin M, Torreilles J (1999) Neurodegenerative disorders: the role of peroxynitrite. Brain Res.Brain Res.Rev. 30:153-163
     Abstract: Inflammatory reaction is thought to be an important contributor to neuronal damage in neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS), amyotrophic lateral sclerosis (ALS) and the parkinsonism dementia complex of Guam. Among the toxic agents released in brain tissues by activated cells, we focus attention in this review on peroxynitrite, the product of the reaction between nitric oxide (NO) and superoxide. Peroxynitrite is a strong oxidizing and nitrating agent which can react with all classes of biomolecules. In the CNS it can be generated by Microglial cells activated by pro-inflammatory cytokines or beta-amyloid peptide (beta-A) and by neurons in three different situations: hyperactivity of glutamate neurotransmission, mitochondrial dysfunction and depletion of L-arginine or tetrahydrobiopterin. The first two situations correspond to cellular responses to an initial neuronal injury and the peroxynitrite formed only exacerbates the inflammatory process, whereas in the third situation the peroxynitrite generated directly contributes to the initiation of the neurodegenerative process

233. Trapp BD, Bo L, Mork S, Chang A (1999) Pathogenesis of tissue injury in MS lesions. J.Neuroimmunol. 98:49-56
     Abstract: multiple sclerosis (MS) is an inflammatory disease of the central nervous system. The primary pathological target in multiple sclerosis is myelin. Most MS patients follow a relapsing-remitting (RR-MS) course for 10 to 15 years that transforms into a chronic or secondary progressive disease (SP-MS). This review summarizes studies from our laboratory that implicate activated Microglia and astrocytes in early stages of myelin destruction in MS brain. In addition, we review evidence that indicates that axonal transection is a major pathological process in multiple sclerosis. Our data support the hypothesis that neurological disability in RR-MS is due to inflammatory demyelination while axonal loss plays a significant role in the irreversible neurological decline in SP-MS. Further elucidation of the pathological targets and pathological mechanisms of tissue destruction in MS brain will help identify new therapeutics

234. van der MK, Hinojoza JR, Sobel RA (1999) Endothelial cell class II major histocompatibility complex molecule expression in stereotactic brain biopsies of patients with acute inflammatory/demyelinating conditions. J.Neuropathol.Exp.Neurol. 58:346-358
     Abstract: To determine if central nervous system (CNS) microvessel endothelial cells express class II major histocompatibility complex (MHC) molecules in early demyelinating lesions in humans, cerebral white matter (WM) biopsies from patients with acute inflammatory/demyelinating conditions, including 4 with multiple sclerosis (MS), were immunostained for class II MHC and other antigens. Eight of 9 biopsies showed focal MHC class II-positive endothelial cells; there were none in the CNS of 1 of the MS patients at autopsy. There were more vessels with class II-positive endothelial cells in areas with intact WM and gliosis than in areas with active demyelination or control WM; class II-positive endothelial cells in small venules and capillaries were adjacent to transmigrating and perivascular CD4-positive cells. By immunoelectron microscopy, class II molecules were localized to vesicles in endothelial cell cytoplasm, suggesting the potential for antigen processing. Perivascular cells, parenchymal Microglia, mononuclear cells and the perinuclear cytoplasm but not the processes of astrocytes were also class II-positive. These data indicate that in acute CNS inflammatory/demyelinating lesions, endothelial cells focally and apparently transiently express class II MHC molecules. This expression implies potential antigen-specific interactions, immunoregulatory or signalling functions in endothelial cells, or it may render them susceptible to CD4-positive cell-mediated cytotoxicity. Thus, class II-positive endothelial cells may have pivotal immunologic roles in initial stages of T cell responses in human CNS WM, particularly in acute MS lesions

235. Woodroofe N, Cross AK, Harkness K, Simpson JE (1999) The role of chemokines in the pathogenesis of multiple sclerosis. Adv.Exp.Med.Biol. 468:135-150

236. Yoshikawa M, Suzumura A, Tamaru T, Takayanagi T, Sawada M (1999) Effects of phosphodiesterase inhibitors on cytokine production by Microglia. Mult.Scler. 5:126-133
     Abstract: Type III and IV phosphodiesterase inhibitors (PDEIs) have recently been shown to suppress the production of TNF-alpha in several types of cells. In the present study, we have shown that all the types of PDEIs, from type I- to V-specific and non-specific, suppress the production of TNF-alpha by mouse Microglia stimulated with lipopolysaccharide (LPS) in a dose-dependent manner. Certain combinations of three different types of PDEIs synergistically suppressed TNF-alpha production by Microglia at a very low concentration (1 microM). Since some PDEIs reportedly pass through the blood-brain barrier (BBB), the combination of three PDEIs may be worth trying in neurological diseases, such as multiple sclerosis and HIV-related neurological diseases in which TNF-alpha may play a critical role. Some PDEIs also suppressed interleukin-I (IL-I) and IL-6 production by mouse Microglia stimulated with LPS. In contrast, the production of IL-10, which is known to be an inhibitory cytokine, was upregulated by certain PDEIs. The suppression of TNF-alpha and induction of IL-10 were confirmed at the mRNA level by RT-PCR. PDEIs may be useful anti-inflammatory agents by downregulating inflammatory cytokines and upregulating inhibitory cytokines in the central nervous system. (CNS)

237. Zipp F, Krammer PH, Weller M (1999) Immune (dys)regulation in multiple sclerosis: role of the CD95-CD95 ligand system. Immunol.Today 20:550-554

238. Aikawa Y, Tanuma N, Shin T, Makino S, Tanaka K, Matsumoto Y (1998) A new anti-rheumatic drug, T-614, effectively suppresses the development of autoimmune encephalomyelitis. J.Neuroimmunol. 89:35-42
     Abstract: In the present study, we examined the therapeutic effects of T-614 (3-formylamino-7-methylsulfonylaminoxy-4H-1-benzopyran-4-one), a new anti-rheumatic drug, on a T cell-mediated autoimmune disease, experimental autoimmune encephalomyelitis (EAE). T-614 dose-dependently suppressed the development of active EAE induced in Lewis rats by immunization with myelin basic protein (MBP) when administered for 2 weeks starting on the day of immunization (day 0 to 14). Amelioration of clinical signs was also obtained by the treatment at the effector phase (day 7 to 14) of the disease. Furthermore, T-614 treatment of recipient rats that had received MBP-sensitized lymphoid cells resulted in suppression of the clinical severity of EAE. Immunohistological examination revealed that the number of TCR alpha beta-expressing T cells and the extent of MHC class II expression in the spinal cord of rats treated with T-614 was markedly reduced. In vitro study using MBP-specific T cells showed that the addition of T-614 inhibited the proliferative responses of T cells and the production of pro-inflammatory cytokines such as IFN-gamma, IL-6 and TNF produced by T and accessory cells. Taken together, these findings imply that T-614 suppresses the development of EAE by inhibiting the proliferation of autoreactive T cells and pro-inflammatory cytokine production not only by T cells but also by macrophages/Microglia. This may be attributable to the result that T-614 is more effective at the effector phase rather than the induction phase. Thus, this drug has a potential value for the treatment of various T cell-mediated autoimmune diseases including multiple sclerosis (MS) as well as rheumatoid arthritis

239. Albright AV, Lavi E, Black JB, Goldberg S, O'Connor MJ, Gonzalez-Scarano F (1998) The effect of human herpesvirus-6 (HHV-6) on cultured human neural cells: oligodendrocytes and Microglia. J.Neurovirol. 4:486-494
     Abstract: Human herpesvirus-6 (HHV-6) is a betaherpesvirus that has been frequently associated with pediatric encephalitis. In 1995 Challoner et al reported that HHV-6 variant B (HHV-6B) was linked to multiple sclerosis (MS) due to the presence of viral DNA and antigen in the oligodendrocytes surrounding MS plaques. These findings led us to examine HHV-6B's in vitro tropism for primary neural cells. HIV-6B mediated cell-to-cell fusion in cultured adult oligodendroglia. Infection of oligodendrocytes was further confirmed by transmission electron microscopy (EM), which showed the presence of intracellular HHV-6 particles, and by PCR for HHV-6 DNA. However, the release of infectious virus was low or undetectable in multiple experiments. Microglia were also susceptible to infection by HHV-6B, as demonstrated by an antigen capture assay. We did not detect infection of a differentiated neuronal cell line (NT2D). Our findings suggest that HHV-6B infection of oligodendrocytes and/or Microglia could potentially play a role in neuropathogenesis

240. Cotman CW, Hailer NP, Pfister KK, Soltesz I, Schachner M (1998) Cell adhesion molecules in neural plasticity and pathology: similar mechanisms, distinct organizations? Prog.Neurobiol. 55:659-669
     Abstract: Brain plasticity and the mechanisms controlling plasticity are central to learning and memory as well as the recovery of function after brain injury. While it is clear that neurotrophic factors are one of the molecular classes that continue to regulate brain plasticity in the adult central nervous system (CNS), less appreciated but equally profound is the role of cell adhesion molecules (CAMs) in plasticity mechanisms such as long term potentiation, preservation of neurons and regeneration. Ironically, however, CAMs can also reorganize the extra-cellular space and cause disturbances that drive the development of brain pathology in conditions such as Alzheimer's disease and multiple sclerosis. Candidate molecules include the amyloid precursor protein which shares many properties of a classical CAM and beta-amyloid which can masquerade as a pseudo CAM. Beta-Amyloid serves as a nidus for the formation of senile plaques in Alzheimer's disease and like CAMs provides an environment for organizing neurotrophic factors and other CAMs. Inflammatory responses evolve in this environment and can initiate a vicious cycle of perpetuated neuronal damage that is medicated by Microglia, complement and other factors. Certain CAMs may converge on common signal transduction pathways involving focal adhesion kinases. Thus a breakdown in the organization of key CAMs and activation of their signal transduction mechanisms may serve as a new principle for the generation of brain pathology

241. Couraud PO (1998) Infiltration of inflammatory cells through brain endothelium. Pathol.Biol.(Paris) 46:176-180
     Abstract: The blood-brain barrier (BBB) restricts exchanges of soluble factors and cells between the blood and the brain, thus playing a crucial role in maintenance of cerebral homeostasis. It is composed of the endothelial cells that line the cerebral capillaries. Cerebral capillaries have a number of distinctive morphological characteristics, including the presence of tight intercellular junctions. Also, the cerebral capillaries are surrounded by astrocytic projections that exert a positive regulatory effect on BBB tightness. One effect of the BBB is that the number of leukocytes that patrol the central nervous system is far lower than in peripheral organs. Nevertheless, massive leukocyte infiltration occurs in some disease states: for instance, numerous activated leukocytes are found in the cerebral parenchyma in patients with multiple sclerosis, and HIV encephalitis is probably due to passage of HIV-infected monocytes through the BBB. Compelling evidence has been obtained that the perivascular astrocytes and Microglial cells, as well as the cerebral endothelial cells, locally produce inflammatory cytokines that increase BBB permeability. Advances have also been made in the identification of leukocyte adhesion molecules expressed at the surface of cerebral endothelial cells. Expression of these molecules is induced by inflammatory cytokines. Interactions between these adhesion molecules and their leukocyte ligands may induce modifications within endothelial cells, including cytoskeleton reorganization and opening of intercellular junctions, which may allow leukocytes to cross the BBB. It is to be hoped that the new insights gained into the mechanisms of leukocyte penetration through the BBB may help to develop novel treatment strategies for neuroinflammatory disorders

242. Diemel LT, Copelman CA, Cuzner ML (1998) Macrophages in CNS remyelination: friend or foe? Neurochem.Res. 23:341-347
     Abstract: Hematogenous macrophages and resident brain Microglia are agents of demyelination in multiple sclerosis (MS) and paradoxically may also participate in remyelination. In vitro studies have shown that macrophage enrichment of aggregate brain cultures promotes myelination per se and enhances the capacity to remyelinate following a demyelinating episode. It has been hypothesized that remyelination in MS is implemented by surviving dedifferentiated oligodendrocytes or by newly recruited progenitors that migrate, proliferate and synthesize myelin in response to signalling molecules in the local environment. We postulate that macrophage-derived cytokines or growth factors may directly or indirectly promote oligodendroglial proliferation and differentiation, contributing to myelin repair in inflammatory demyelinating disease

243. Gasque P, Singhrao SK, Neal JW, Wang P, Sayah S, Fontaine M, Morgan BP (1998) The receptor for complement anaphylatoxin C3a is expressed by myeloid cells and nonmyeloid cells in inflamed human central nervous system: analysis in multiple sclerosis and bacterial meningitis. J.Immunol. 160:3543-3554
     Abstract: The complement anaphylatoxins C5a and C3a are released at the inflammatory site, where they contribute to the recruitment and activation of leukocytes and the activation of resident cells. The distribution of the receptor for C5a (C5aR) has been well studied; however, the receptor for C3a (C3aR) has only recently been cloned, and its distribution is uncharacterized. Using a specific affinity-purified anti-C3aR peptide Ab and oligonucleotides for reverse transcriptase-PCR analysis, C3aR expression was characterized in vitro on myeloid and nonmyeloid cells and in vivo in the brain. C3aR was expressed by adult astrocytes, astrocyte cell lines, monocyte lines THP1 and U937, neutrophils, and monocytes, but not by K562 or Ramos. C3aR staining was confirmed by flow cytometry, confocal imaging, and electron microscopy analysis. A 65-kDa protein was immunoprecipitated by the anti-C3aR from astrocyte and monocyte cell lysates. Our results at the protein level were confirmed at the mRNA level. Using reverse transcriptase-PCR, Southern blot, and sequencing we found that C3aR mRNA was expressed by fetal astrocytes, astrocyte cell lines, and THP1, but not by K562 or Ramos. The astrocyte C3aR cDNA was identical with the reported C3aR cDNA. C3aR expression was not detected in normal brain sections. However, a strong C3aR staining was evident in areas of inflammation in multiple sclerosis and bacterial meningitis. In meningitis, C3aR was abundantly expressed by reactive astrocytes, Microglia, and infiltrating cells (macrophages and neutrophils). In multiple sclerosis, infiltrating lymphocytes did not express C3aR, but a strong staining was detected on smooth muscle cells (pericytes) surrounding blood vessels

244. Gasque P, Jones J, Singhrao SK, Morgan B (1998) Identification of an astrocyte cell population from human brain that expresses perforin, a cytotoxic protein implicated in immune defense. J.Exp.Med. 187:451-460
     Abstract: The brain is an immunoprivileged organ isolated from the peripheral immune system. However, it has been shown that resident cells, notably astrocytes and Microglia, can express numerous innate immune molecules, providing the capacity to generate a local antipathogen system. Perforin is a cytolytic protein present in the granules of cytotoxic T lymphocytes and natural killer cells. Expression in cells other than those of the hemopoetic lineage has not been described. We report here that fetal astrocytes in culture (passages 2 to 15), astrocytoma, and adult astrocytes expressed perforin. Reverse transcriptase polymerase chain reaction followed by Southern blot was carried out using multiple specific primers and all cDNAs were cloned and sequenced. Human fetal astrocyte perforin cDNA sequence was approximately 100% identical to the reported perforin cDNA cloned from T cells. Western blot analysis using monoclonal and polyclonal antiperforin peptide antibodies revealed a protein of 65 kD in both human fetal astrocyte and rat natural killer cell lysates (n = 4). Immunostaining followed by FACS(R) and confocal and electron microscopy analysis revealed that perforin was expressed by 40-50% of glial fibrillary acidic protein positive cells present in the fetal brain culture (n = 11). Perforin was not localized to granules in astrocytes but was present throughout the cytoplasm, probably in association with the endoplasmic reticulum. Perforin was not detected in normal adult brain tissue but was present in and around areas of inflammation (white and grey matter) in multiple sclerosis and neurodegenerative brains. Perforin-positive cells were identified as reactive astrocytes. These findings demonstrate that perforin expression is not unique to lymphoid cells and suggest that perforin produced by a subpopulation of astrocytes plays a role in inflammation in the brain

245. Gebicke-Haerter PJ, Lieb K, Illes P, Berger M (1998) [Microglia: mechanisms of activation and significance in pathogenesis of neuropsychiatric illnesses]. Nervenarzt 69:752-762
     Abstract: Microglia are the resident macrophages of the brain. They are the central cellular element to initiate defense mechanisms against destructive environmental influences and to facilitate regenerative processes. No other cell type of the brain is endowed with a comparably comprehensive, immunocompetent machinery like Microglia. It encompasses cell proliferation, migration and differentiation into full-blown macrophages able to present antigen and to phagocytose cell debris. Relatively little is known about these stages of Microglia activation on the cellular and molecular level, although Microglia have been described as a separate cell type of the brain as early as in the 30ies of this century by P.del Rio Hortega. This review summarizes the data that have accumulated until now in this respect and tries to embed them into a clinical framework. Special focus has been given to the role of this cell type in the development and progression of multiple sclerosis, HIV-associated dementia and Alzheimer's disease

246. Gveric D, Kaltschmidt C, Cuzner ML, Newcombe J (1998) Transcription factor NF-kappaB and inhibitor I kappaBalpha are localized in macrophages in active multiple sclerosis lesions. J.Neuropathol.Exp.Neurol. 57:168-178
     Abstract: NF-kappaB is a transcription factor family which on translocation to the nucleus regulates gene expression during cell activation. As such, NF-kappaB may play a role in the Microglial response to myelin damage in multiple sclerosis (MS) lesions. Here the cellular localization of NF-kappaB and expression of the inhibitory I kappaBalpha were examined by immunocytochemistry on central nervous system (CNS) tissue from MS and control cases. In normal control white matter, the active form of the NF-kappaB subunit RelA (p65) was localized in Microglial nuclei, while the c-Rel and p50 subunits and the inhibitory I kappaBalpha were restricted to the cytoplasm. In contrast, in actively demyelinating plaques, the RelA, c-Rel, and p50 subunits of NF-kappaB and I kappaBalpha were all present in macrophage nuclei in both parenchymal and perivascular areas. RelA was also found in the nuclei of a subset of hypertrophic astrocytes. Only c-Rel had a nuclear localization in lymphocytes in perivascular inflammatory cuffs. Our results suggest that constitutive activation of the RelA subunit in the nuclei of resting Microglia may facilitate a rapid response to pathological stimuli in the CNS. Activation of the inducible NF-kappaB pool in macrophages in MS lesions could amplify the inflammatory reaction through upregulation of NF-kappaB-controlled adhesion molecules and cytokines

247. Hays SJ (1998) Therapeutic approaches to the treatment of neuroinflammatory diseases. Curr.Pharm.Des 4:335-348
     Abstract: Microglia cells are present in the central nervous system and respond quickly to pathogenic stimuli in order to protect the brain. When these immunological responses activate inappropriately or are prolonged, they can contribute to the neuronal damage observed in many neurodegenerative diseases. A variety of immune system modulators including complement proteins, inflammatory cytokines such IL-1 alpha, IL-1 beta, IL-3, IL-6, TNF-alpha, and S100 beta, colony-stimulating factor-1, coagulation proteins and matrix metalloproteases are made by both Microglia and astrocytes. Additionally astrocytes, the predominant glial component of the brain, express cell-adhesion molecules, cytokine receptors and induce nitric oxide synthease. The pathophysiology of Alzheimer's disease, stroke, traumatic brain injury, and multiple sclerosis suggest that a large portion of the irreversible damage observed can be attributed to a neuroinflammatory mechanism. The immunomodulators of these diseases are reviewed and new agents within specific molecular mechanisms are presented and discussed

248. Hu P, Pollard J, Hunt N, Taylor J, Chan-Ling T (1998) Microvascular and cellular responses in the optic nerve of rats with acute experimental allergic encephalomyelitis (EAE). Brain Pathol. 8:475-486
     Abstract: The optic nerve of rats with EAE was examined at various times to determine the integrity of the blood-brain barrier (BBB) and to assess monocyte-macrophage, T cell, and Microglial responses. In naive control animals, leakage of horseradish peroxidase (HRP) and the presence of cells expressing major histocompatibility complex (MHC) class II antigen were evident in the meninges of the retrobulbar optic nerve. In rats with EAE, Microglia in the region of the lamina cribrosa and in the regions adjacent to the meninges became activated from day 7 to 8 postinduction (pi). HRP leakage was also evident in the region of the lamina cribrosa from day 7 to 8 pi. On day 8 pi, infiltration of inflammatory cells and Monastral blue leakage were apparent in the myelinated region of the optic nerve. The intensity of these cellular and vascular changes peaked at day 12 pi, when signs of clinical disease became manifest. Monocytes-macrophages expressing MHC class II and the ED1 antigen, together with lymphocytes expressing the alphabetaT cell receptor, constituted the major proportion of cells associated with inflammatory lesions. Thus: (i) the inherent weakness of the BBB as well as the presence of both antigen (myelin) and MHC class II+ cells in the retrobulbar optic nerve are likely susceptibility factors for the frequent involvement of this region in EAE and multiple sclerosis; and (ii) activation of Microglia occurs early in the pathogenesis of experimental optic neuritis

249. Khan OA, Jiang H, Subramaniam PS, Johnson HM, Dhib-Jalbut SS (1998) Immunomodulating functions of recombinant ovine interferon tau: potential for therapy in multiple sclerosis and autoimmune disorders. Mult.Scler. 4:63-69
     Abstract: The interferons (IFN) are a family of complex proteins possessing antiviral, antiproliferative, and immunomodulatory activities. Two type I recombinant human IFN have been recently approved for the treatment of multiple sclerosis (MS). However, use of high dose type I IFN treatment in MS patients has been limited by dose-related toxicity. Ovine IFN tau is a unique type I interferon discovered for its role in the animal reproductive cycle. It differs from other type I IFNs in that it is remarkably less toxic even at high concentrations, is able to cross species barriers, and is not inducible by viral infection. Ovine IFN tau has been shown to be very effective in the treatment of animal models of MS. In this study, we examined the toxicity of OvIFN tau on human T-cells at high doses and its immunregulatory properties at equivalent doses. Our experiments confirmed the remarkably non-toxic nature of OvIFN tau on human cells at high concentrations as well as immunomodulating properties consistent with other type I IFNs including an antilymphoproliferative effect and inhibition of IFN gamma-induced HLA class II expression. These results suggest that OvIFN tau could be developed into a potentially less toxic therapeutic option for immune-mediated disorders including MS

250. Kiefer R, Schweitzer T, Jung S, Toyka KV, Hartung HP (1998) Sequential expression of transforming growth factor-beta1 by T-cells, macrophages, and Microglia in rat spinal cord during autoimmune inflammation. J.Neuropathol.Exp.Neurol. 57:385-395
     Abstract: Transforming growth factor-beta1 (TGF-beta1) is crucially involved in regulating inflammatory events during experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis. Despite accumulating evidence for local expression of TGF-beta1 in the inflamed nervous system, uncertainty remains regarding its cellular source. We have investigated the temporospatial distribution of TGF-beta1 gene expression in rat spinal cord during EAE. In actively induced EAE, in situ hybridization revealed strong expression of TGF-beta1 in meningeal and perivascular mononuclear infiltrates at onset of the disease, continued expression in perivascular infiltrates and scattered mononuclear cells at maximal disease severity, and expression in scattered parenchymal cells during recovery. Double labeling studies revealed subpopulations of infiltrating T-cells to be the major source of TGF-beta1 early in the disease, followed by macrophages at peak severity and Microglial cells during the recovery phase of EAE. Astrocytes and neurons did not express TGF-beta1. Quantification of mRNA by Northern blot analysis revealed that cellular expression of TGF-beta1 by T-cells, macrophages, and Microglia sums up to a long-lasting elevation of TGF-beta1 mRNA extending well into the recovery phase. Our data indicate cellular diversity and suggest functional diversity of TGF-beta1 gene expression during EAE. While TGF-beta1 expressed early in the disease by T-cells may contribute to inflammatory lesion development, Microglial cells may potentially contribute to recovery by expressing immunosuppressive TGF-beta1 during remission

251. Liedtke W, Cannella B, Mazzaccaro RJ, Clements JM, Miller KM, Wucherpfennig KW, Gearing AJ, Raine CS (1998) Effective treatment of models of multiple sclerosis by matrix metalloproteinase inhibitors. Ann.Neurol. 44:35-46
     Abstract: The proinflammatory Th1 cytokine, tumor necrosis factor-alpha (TNF alpha), the cell death signaling molecule FasL, and several extracellular matrix degrading metalloproteinases have been implicated in the pathogenesis of multiple sclerosis (MS). The latter enzymes, as well as TNF alpha-converting enzyme and FasL-converting enzyme, can be blocked by matrix metalloproteinase inhibitors (MMPIs). In this study, we show that a potent MMPI was clinically effective in an animal model for MS, experimental autoimmune encephalomyelitis (EAE) in the SJL/J mouse. Efficacy was remarkable, as indicated by blocking and reversal of acute disease and reduced number of relapses and diminished mean cumulative disease score in chronic relapsing animals. Also, demyelination and glial scarring were significantly decreased in MMPI-treated mice with chronic relapsing EAE, as was central nervous system gene expression for TNF alpha and fasL. It is interesting that expression of the beneficial cytokine interleukin-4 (IL-4) was increased, and IL-4 was expressed on glial cells. The relevance of these compounds for MS was underscored by their ability to specifically inhibit TNF alpha shedding and cytotoxicity of myelin-autoreactive human cytotoxic CD4+ T-cell clones. This is the first report to show a positive effect by MMPIs on chronic relapsing EAE, its central nervous system cytokine profile, and on TNF alpha shedding by human myelin-autoreactive T cells

252. Link H (1998) The cytokine storm in multiple sclerosis. Mult.Scler. 4:12-15
     Abstract: MS is associated with a cytokine storm characterized by the parallel upregulation of proinflammatory (IFN-gamma, TNF-alpha, and beta, and IL-12) and immune response-down-regulating (TGF-beta, IL-10) cytokines. Also IL-6 and the cytolytic molecule perforin are upregulated. Even when evaluated in individual MS patients over the disease course, no Th1/Th2 dichotomy is obvious but, instead, upregulation of Th1 + Th2 + Th3 cytokines simultaneously, probably reflecting the complex pathology of MS in lesion size, time and distribution in the individual patient. Few correlations have been observed between cytokines and clinical MS variables, though upregulation of TGF-beta seems to correlate with benign course and minor disability. Both pro- and antiinflammatory cytokines are also produced by Microglia and astrocytes, constituting a CNS-cytokine network that interacts with the cytokine network of the immune system. This complexity is to be kept in mind when searching for cytokine abnormalities in MS

253. Liu JS, Amaral TD, Brosnan CF, Lee SC (1998) IFNs are critical regulators of IL-1 receptor antagonist and IL-1 expression in human Microglia. J.Immunol. 161:1989-1996
     Abstract: Because IL-1 is implicated in the pathogenesis of multiple sclerosis, and IFNs are known to alter disease course, we sought to determine whether IFNs can regulate the expression of IL-1 and IL-1R antagonist (IL-1Ra) in primary cultures of human Microglia and astrocytes. We found that IL-1 and IL-1Ra are products of Microglia but not astrocytes, and IFN-beta and IFN-gamma differentially modulate LPS- and cytokine-induced IL-1 and IL-1Ra. IFN-beta induces IL-1Ra and augments LPS- and IL-4-induced IL-1Ra, but suppresses LPS- and IL-1-induced IL-1, shifting the balance toward the expression of the IL-1Ra. Like IFN-beta, IFN-gamma suppresses the expression of both LPS and IL-1-induced IL-1beta. However, IFN-gamma also suppresses the expression of IFN-beta- and IL-4-induced IL-1Ra so that IFN-gamma may enhance or suppress IL-1 activity depending on the other cytokines present. IL-4 has similar effects to IFN-beta; however, other anti-inflammatory cytokines, did not regulate IL-1 or IL-1Ra in human Microglia. Our data demonstrate a novel suppressive effect of IFN-beta and IL-4 on IL-1 activity in human Microglia, suggesting that IFN-beta, a therapeutic agent used for multiple sclerosis, could have wider applications in the treatment of other central nervous system disorders in which IL-1 activity has been implicated in the pathogenesis

254. Liu X, Mashour GA, Webster HF, Kurtz A (1998) Basic FGF and FGF receptor 1 are expressed in Microglia during experimental autoimmune encephalomyelitis: temporally distinct expression of midkine and pleiotrophin. Glia 24:390-397
     Abstract: Heparin-binding growth factors have been implicated in central nervous system development, regeneration and pathology. To assess the expression pattern and possible function in multiple sclerosis, the heparin-binding growth factors pleiotrophin (PTN), midkine (MK), basic fibroblast growth factor (FGF-2) and one of its receptors (FGFR1/flg) mRNA and protein levels were examined in an experimental autoimmune encephalomyelitis (EAE) model in the Lewis rat. We assessed the time course of expression of PTN, MK and FGF-2 during EAE and determined the cellular origin of FGF-2 and FGFR1 in normal spinal cord and during inflammatory demyelination. Basal expression of PTN and MK mRNAs in normal spinal cords was significantly upregulated after induction of EAE. MK expression was upregulated two to threefold correlating with disease progression, whereas PTN expression reached peak levels threefold above basal levels during the clinical recovery period. FGF-2 mRNA expression was low in normal spinal cord and dramatically increased in correlation with progressive demyelination. FGF-2 was confined to neurons in normal tissue and shifted dramatically to Microglia, paralleling their activation during EAE. Double immunohistochemistry revealed colocalization of FGF-2 to activated Microglia/macrophages with strongest expression in the macrophage-rich perivascular core area and Microglial expression at the edges of white and gray matter perivascular regions. FGFR1, like its ligand, was induced in activated macrophages/Microglia. Growth factor expression in demyelinating diseases could serve several functions, e.g., to modulate the activity of Microglia/macrophage in an autocrine fashion, to induce the expression of other factors like insulin-like growth factor 1 or plasminogen activator, which can effect regeneration or degeneration, respectively, and finally to stimulate directly localized proliferation and/or regeneration of oligodendrocytes within the lesion area

255. Maatta JA, Sjoholm UR, Nygardas PT, Salmi AA, Hinkkanen AE (1998) Neutrophils secreting tumor necrosis factor alpha infiltrate the central nervous system of BALB/c mice with experimental autoimmune encephalomyelitis. J.Neuroimmunol. 90:162-175
     Abstract: Experimental autoimmune encephalomyelitis (EAE) can be induced in resistant BALB/c mice by ultrasound-formed adjuvant emulsion. In contrast to susceptible mouse strains large numbers of neutrophils secreting TNF-alpha occupied the central nervous system (CNS) of BALB/c mice with severe EAE, whereas only small numbers of macrophages and CD4+ T-cells could be detected. CNS infiltration was preceded with activation of Microglial cells. Ultrasound formed adjuvant induced early IFN-gamma expression in popliteal lymph nodes of BALB/c mice, whereas conventional adjuvant induced delayed IFN-gamma production. Although the clinical outcome of EAE was similar to that seen in susceptible mice, the pathogenesis was distinct having possible implications on the different forms seen in multiple sclerosis

256. Matyszak MK (1998) Inflammation in the CNS: balance between immunological privilege and immune responses. Prog.Neurobiol. 56:19-35
     Abstract: Inflammatory components play an important part in many diseases of the central nervous system (CNS). Recent evidence suggests that this may also be true of diseases which were previously considered as purely neuro-degenerative. However, it is also clear that inflammatory responses in the CNS differ in many ways from responses in non-CNS tissues. Some of these differences have been demonstrated by the use of animal models. For example, when bacteria are injected into the brain parenchyma, they induce a typical acute inflammatory response. However, unlike in other tissues, bacteria which are not cleared from the brain parenchyma remain undetected by the immune system. Some bacteria, such as bacillus Calmette-Guerin, can persist in the brain parenchyma for months sequestered in Microglia and perivascular macrophages. When an animal with an intraparenchymal bacteria deposit is later sensitised peripherally, an immune response is evoked at the site of the deposits. The lesions induced in the CNS parenchyma are T-cell mediated and show characteristics typical of a delayed-type hypersensitivity response. The lesions produce a breakdown of the blood-brain barrier and demyelination. These immune responses are similar to those described for multiple sclerosis lesions. The responses to bacteria are unique to the brain parenchyma. Pathogens injected into the ventricles induce inflammatory responses similar to those in other non-CNS tissues: there is an acute inflammatory response which develops spontaneously into an immune mediated response within the first week

257. Mayer AM (1998) Therapeutic implications of Microglia activation by lipopolysaccharide and reactive oxygen species generation in septic shock and central nervous system pathologies: a review. Medicina (B Aires) 58:377-385
     Abstract: The pathophysiology of organ system failure in sepsis, in particular the effects of septic shock on the central nervous system, are still incompletely understood. Lipopolysaccharide (LPS) from Gram-negative bacteria affects the permeability of the blood-brain barrier and causes the activation of brain Microglia. A growing body of research supports involvement of activated brain Microglia in brain pathologies caused by infectious diseases, trauma, tumors, ischemia, Alzheimer's disease, Parkinson's disease, Down's syndrome, multiple sclerosis and AIDS. Those seminal studies that have contributed to the characterization of the in vivo and in vitro effects of LPS on Microglia function, mediator generation and receptor expression are presented within a historical perspective. In particular, all those in vitro studies on O2-, H2O2 and NO. generation by either unprimed or primed Microglia have been extensively reviewed. The apparent controversial effect of LPS on Microglia O2- is discussed. Because treatment modalities for septic shock have not significantly affected the current high mortality, alternative strategies with antioxidants are currently being investigated. Reduction of Microglia O2- generation is proposed as a possible complementary strategy to antioxidative therapy for septic shock and CNS pathologies that involve activated Microglia

258. McManus CM, Brosnan CF, Berman JW (1998) Cytokine induction of MIP-1 alpha and MIP-1 beta in human fetal Microglia. J.Immunol. 160:1449-1455
     Abstract: Leukocyte infiltration into the central nervous system (CNS) is a key event in the inflammatory processes of neuroimmunologic diseases. Microglia, resident macrophages of the CNS, may contribute to this process by elaborating chemoattractants that are capable of recruiting leukocytes across the blood-brain barrier. Such factors have been detected in the CNS of animal models of multiple sclerosis and in the brains of human and nonhuman primates with AIDS encephalitis. As the expression of these chemoattractants may play an important role in the initiation and progression of neuroimmunologic diseases, we analyzed expression of the chemokines MIP-1 alpha, MIP-1 beta, MCP-1, and RANTES in human fetal Microglial cultures. Unstimulated Microglia expressed minimal levels of MIP-1 alpha, MIP-1 beta, and MCP-1, while RANTES was undetectable. In response to LPS, TNF-alpha, or IL-1 beta, both MIP-1 alpha and MIP-1 beta were induced at the mRNA and protein levels in a dose- and time-dependent manner. IFN-gamma did not significantly induce chemokine expression. MCP-1 was detectable in LPS- and cytokine-treated Microglia. TGF-beta, a cytokine with down-modulatory effects on other cell types, had little effect on chemokine expression in Microglia when used concomitantly before or during treatment with LPS. These results illustrate the ability of certain inflammatory stimuli to induce expression of MIP-1 alpha, MIP-1 beta, and MCP-1 by human fetal Microglia. The expression of these chemoattractants may function to recruit inflammatory cells into the CNS during the course of neuroimmunologic diseases and may modulate the ability of HIV to infect the CNS

259. Minghetti L, Polazzi E, Nicolini A, Levi G (1998) Opposite regulation of prostaglandin E2 synthesis by transforming growth factor-beta1 and interleukin 10 in activated Microglial cultures. J.Neuroimmunol. 82:31-39
     Abstract: We have recently shown that prostaglandin E2 (PGE2) synthesis in activated Microglia is tightly regulated by several substances (NO, neurotransmitters, pro-inflammatory cytokines), that might originate from intrinsic brain cells or from hematogenous cells infiltrating the brain in the course of inflammatory diseases. In view of the important immunoregulatory and neuroprotective functions recently attributed to PGE2, in the present study we extended our analysis of factors regulating PGE2 synthesis in rat Microglial cultures to two anti-inflammatory and immunosuppressive cytokines, transforming growth factor beta1 (TGF-beta1) and interleukin 10 (IL-10), which share with PGE2 the ability to strongly deactivate peripheral macrophages and Microglial cells. Moreover, we looked at the effect of the two cytokines on nitric oxide (NO) synthesis, another important Microglial effector, whose synthesis is linked to that of PGE2 by complex feed-back mechanisms. We found that while both cytokines inhibited LPS-induced NO release, they had distinct and opposite regulatory activities on PGE2 production. In fact, while TGF-beta1 enhanced LPS-induced PGE2 synthesis, IL-10 showed an inhibitory effect. The two cytokines acted mainly by regulating the LPS-induced expression of the rate limiting enzymes of the two metabolic pathways, cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS). Moreover, TGF-beta1 counteracted the effect of the pro-inflammatory cytokine interferon-gamma, which in the same cultures has been shown to downregulate PGE2 and to upregulate NO synthesis. Although the present in vitro observations cannot be directly extrapolated to the in vivo situation, they may provide a novel clue for understanding the specific role of TGF-beta1 and IL-10 in several neurological diseases such as multiple sclerosis, in which their cerebral level was found to be elevated

260. Morris CS, Esiri MM (1998) The expression of cytokines and their receptors in normal and mildly reactive human brain. J.Neuroimmunol. 92:85-97
     Abstract: There are many inflammatory diseases of the brain such as AIDS, other viral encephalitides and multiple sclerosis all of which are probably influenced by both systemic and focal CNS cytokine release. We have studied the expression of a wide range of pro- and anti-inflammatory cytokines and their receptors, beta2-microglobulin, and MHC Class II, using immunocytochemistry on cryostat sections of normal and mildly reactive human brain. The aim was to try to determine the cytokine 'baseline' expression in normal human brain and the results obtained indicated very low expression of various cytokines and their receptors, mainly by Microglia and macrophages with some endothelial expression

261. Mujtaba MG, Streit WJ, Johnson HM (1998) IFN-tau suppresses both the autoreactive humoral and cellular immune responses and induces stable remission in mice with chronic experimental allergic encephalomyelitis. Cell Immunol. 186:94-102
     Abstract: We have previously shown that interferon-tau (IFN-tau) pretreatment inhibits the development of both acute and chronic mouse experimental allergic encephalomyelitis (EAE), an animal model for the human demyelinating disease multiple sclerosis (MS). IFN-tau is a type I IFN that has pregnancy recognition hormone activity in ruminants. Here we show that IFN-tau induced remission in SJL/J mice that had ongoing chronic active EAE disease and protected mice against secondary relapses. IFN-tau treatment reversed lymphocyte infiltration and Microglial activation in the central nervous system. Mice that were treated with IFN-tau had lower levels of anti-MBP antibodies than untreated mice in both chronic and acute forms of EAE. MBP induced proliferation in B cells from EAE mice, but treatment with IFN-tau either in vivo or in vitro blocked activation. Furthermore, IFN-tau inhibited MBP activation of T cells from EAE mice. Thus, IFN-tau inhibits the humoral arm as well as the cellular arm of the autoimmune disease EAE. The data presented here show that IFN-tau inhibits both B cell and T cell responses in EAE as well as active, chronic EAE, and this may help explain the effectiveness of type I IFNs in treatment of MS

262. Nakajima K, Kohsaka S (1998) [Microglia: function in the pathological state]. No To Shinkei 50:5-16

263. Nataf S, Davoust N, Barnum SR (1998) Kinetics of anaphylatoxin C5a receptor expression during experimental allergic encephalomyelitis. J.Neuroimmunol. 91:147-155
     Abstract: In this study, we investigated the expression of the C5aR in spinal cords of Lewis rats with experimental allergic encephalomyelitis (EAE). Using in situ hybridization (ISH) we analyzed the kinetics of C5aR at different time points of EAE (preclinical stage, clinical peak, remission phase). We observed that C5aR mRNA was readily detected in the CNS of EAE rats at all the stages of the disease. Using a combination of ISH and immunohistochemistry, we formally demonstrated that C5aR is strongly expressed on Microglial cells and hypertrophic astrocytes during EAE. The potential involvement of C5a receptor in EAE physiopathology is discussed

264. Raine CS, Bonetti B, Cannella B (1998) multiple sclerosis: expression of molecules of the tumor necrosis factor ligand and receptor families in relationship to the demyelinated plaque. Rev.Neurol.(Paris) 154:577-585
     Abstract: The molecules that comprise the tumor necrosis factor ligand and receptor (TNF-L and TNF-R) families play important roles in tissue homeostasis and in multiple sclerosis (MS). For example, levels of the TNF ligand (TNF alpha; cachectin) correlate with disease progression and lymphotoxin (LT, TNF beta) has been localized in MS lesions. Members of the TNF-R family are typical signal sensors which upon binding with ligand aggregate and recruit signal transducers. To date, no TNF-R molecules have been reported in MS although TNF-RI and RII have been localized to oligodendrocytes in culture. In the present study, the expression of TNF, LT alpha (the soluble form of LT), LT beta (the beta chain of LT alpha beta, the membrane-bound form of LT), TNF-RI, TNF-RII, LT beta-R, FasL, and Fas receptor in MS lesions has been examined by immunohistochemistry for protein and by RT-PCR for mRNA. In addition, the TUNEL technique for DNA fragmentation was applied to detect apoptosis. The results have shown that contrarily to predictions, oligodendrocytes around active MS lesions frequently expressed TNF-R molecules belonging to the apoptotic cascade. However, these cells did not undergo apoptosis, as judged by TUNEL. On the other hand, lymphocytes (and a few Microglial cells) in the same tissue displayed apoptosis. Microglial cells were the major effector cells in the CNS and expressed TNF, LT alpha and FasL. LT beta expression was seen on astrocytes and oligodendrocytes, and LT beta-R on astrocytes. We conclude that TNF-L and TNF-R molecules are extensively expressed in MS, that their expression occurs at high levels but is not specific for MS, and that oligodendrocytes are depleted by a cytolytic mechanism, not by apoptosis

265. Reder AT, Genc K, Byskosh PV, Porrini AM (1998) Monocyte activation in multiple sclerosis. Mult.Scler. 4:162-168
     Abstract: Monocytes, macrophages, and Microglia have a central role in the CNS inflammation of MS. Monocytes are important in the earliest events in MS. Peripheral blood monocytes secrete prostaglandins before MS attacks. During clinical activity monocyte activation markers increase and IL-1 and TNF-alpha levels are elevated. Other monocyte products such as IL-10 reduce inflammation. IL-10 mRNA in MNC is increased during stable disease. Manipulation of monokine secretion and expression of monocyte surface proteins are reasonable approaches for immune therapy of MS

266. Schonrock LM, Kuhlmann T, Adler S, Bitsch A, Bruck W (1998) Identification of glial cell proliferation in early multiple sclerosis lesions. Neuropathol.Appl.Neurobiol. 24:320-330
     Abstract: multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system which leads to destruction of myelin sheaths. The patterns of cell proliferation in the early course of the disease are largely unknown. The present study used immunohistochemical identification of proliferating glial cells in stereotactic brain biopsy material of eight patients with early chronic MS. Double-labelling with the proliferation marker MIB-1 detected proliferating oligodendrocytes (MOG), astrocytes (GFAP) and Microglia/macrophages (Ki-M1P). The majority of proliferating cells were macrophages/Microglia when compared with oligodendrocytes (P > 0.005) or astrocytes (P > 0.0005); only a minor proportion of Microglia/macrophages, however, proliferated in situ. Astrocytic and oligodendroglial proliferation was sparse to absent and showed significant variations between different patients. There were statistically significant differences when comparing the amount of proliferation between lesions of different demyelinating activity: highest numbers of proliferating cells were found in early active lesions compared with demyelinated and early remyelinated lesions (P > 0.05) or the periplaque white matter (P > 0.01). MOG-positive oligodendrocytes proliferated occasionally in the early stages of lesion formation; this proliferation occurred in four cases but was independent of the stage of the disease. Since MOG is expressed by mature oligodendrocytes, and not by immature precursors, this might suggest a potential role for the proliferation of mature surviving oligodendrocytes with subsequent remyelination

267. Scolding NJ, Morgan BP, Compston DA (1998) The expression of complement regulatory proteins by adult human oligodendrocytes. J.Neuroimmunol. 84:69-75
     Abstract: In multiple sclerosis, infiltrating T lymphocytes and perivascular Microglia may initiate demyelinating lesions, but a role for antibody and complement in the ensuing inflammatory damage to myelin and oligodendrocytes is likely. In most tissues, ubiquitously expressed complement regulatory proteins prevent autologous destruction, protecting host cells from the powerful cytolytic activity of activated complement. We have studied the surface expression of a comprehensive range of complement regulatory proteins by live adult human oligodendrocytes in vitro. Only DAF of the activation pathway regulators was expressed, not CR1 or MCP. Of the membrane attack pathway regulatory proteins, HRF was not expressed, while substantial heterogeneity of CD59 expression by oligodendrocytes was found. Clusterin expression was not found. A relative deficiency of protective complement regulatory proteins on human oligodendrocytes may contribute to their selective damage in multiple sclerosis

268. Shields DC, Tyor WR, Deibler GE, Banik NL (1998) Increased calpain expression in experimental demyelinating optic neuritis: an immunocytochemical study. Brain Res. 784:299-304
     Abstract: Since calcium activated neutral proteinase (calpain) is present in the central nervous system (CNS) and degrades myelin proteins, this endopeptidase has been suggested to play a role in myelin destruction in demyelinating diseases such as multiple sclerosis (MS). In the present study, calpain immunocytochemical expression was examined in Lewis rats with acute experimental allergic encephalomyelitis (EAE), an animal model for MS and optic neuritis. To identify cells expressing calpain, we labeled rat optic nerve sections for calpain with a polyclonal myelin calpain antibody and with monoclonal antibodies for glial (GFAP, OX42) and inflammatory (CD2, ED2, ED1, IFN-gamma) cell-specific markers. The results showed increased calpain expression in Microglia (OX42) and infiltrating macrophages (ED1,2) in EAE compared to normal controls. Astrocytes constitutively expressed calpain in controls and acute EAE. Reactive astrocytes in EAE located in or near inflammatory foci, exhibited markedly increased calpain expression. Most T cells in acute EAE showed low level calpain expression while activated IFN-gamma-producing lymphocytes in inflammatory foci exhibited elevated levels of calpain expression. Thus, our results demonstrate increased calpain expression (at transcriptional and/or translational levels) in a rat model of optic neuritis. A role for calpain in myelin destruction during optic neuritis may be relevant to the pathogenesis of this disorder

269. Shields DC, Tyor WR, Deibler GE, Hogan EL, Banik NL (1998) Increased calpain expression in activated glial and inflammatory cells in experimental allergic encephalomyelitis. Proc.Natl.Acad.Sci.U.S.A 95:5768-5772
     Abstract: In demyelinating diseases such as multiple sclerosis (MS), myelin membrane structure is destabilized as myelin proteins are lost. Calcium-activated neutral proteinase (calpain) is believed to participate in myelin protein degradation because known calpain substrates [myelin basic protein (MBP); myelin-associated glycoprotein] are degraded in this disease. In exploring the role of calpain in demyelinating diseases, we examined calpain expression in Lewis rats with acute experimental allergic encephalomyelitis (EAE), an animal model for MS. Using double-immunofluorescence labeling to identify cells expressing calpain, we labeled rat spinal cord sections for calpain with a polyclonal millicalpain antibody and with mAbs for glial (GFAP, OX42, GalC) and inflammatory (CD2, ED2, interferon gamma) cell-specific markers. Calpain expression was increased in activated Microglia (OX42) and infiltrating macrophages (ED2) compared with controls. Oligodendrocytes (galactocerebroside) and astrocytes (GFAP) had constitutive calpain expression in normal spinal cords whereas reactive astrocytes in spinal cords from animals with EAE exhibited markedly increased calpain levels compared with astrocytes in adjuvant controls. Oligodendrocytes in spinal cords from rats with EAE expressed increased calpain levels in some areas, but overall the increases in calpain expression were small. Most T cells in grade 4 EAE expressed low levels of calpain, but interferon gamma-positive cells demonstrated markedly increased calpain expression. These findings suggest that increased levels of calpain in activated glial and inflammatory cells in EAE may contribute to myelin destruction in demyelinating diseases such as MS

270. Simpson JE, Newcombe J, Cuzner ML, Woodroofe MN (1998) Expression of monocyte chemoattractant protein-1 and other beta-chemokines by resident glia and inflammatory cells in multiple sclerosis lesions. J.Neuroimmunol. 84:238-249
     Abstract: Beta-chemokines induce the directional migration of monocytes and T lymphocytes and are thus associated with chronic inflammation. Using immunocytochemistry and in situ hybridisation (ISH) techniques, we have examined the expression of the beta-chemokines monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein (MIP)-1alpha, MIP-1beta, and RANTES (regulated upon activation, normal T cell expressed and secreted) in post-mortem human brain from multiple sclerosis (MS) cases, at different stages of lesion development. In actively demyelinating MS plaques RANTES expression was restricted to the blood vessel endothelium, perivascular cells and surrounding astrocytes, suggesting a role in the recruitment of inflammatory cells from the circulation. MCP-1 was expressed by astrocytes and macrophages within acute MS lesions, but was restricted to reactive astrocytes in the parenchyma surrounding the lesion. MIP-1alpha was expressed by astrocytes and macrophages within the plaque, while MIP-1beta was expressed by macrophages and Microglia within the lesion, and by Microglia in surrounding white matter. Glial cells may be stimulated to produce chemokines and continue the local inflammatory response by forming chemotactic gradients to attract T cells and mononuclear phagocytes from the circulation and surrounding tissue

271. Singh I, Pahan K, Khan M, Singh AK (1998) Cytokine-mediated induction of ceramide production is redox-sensitive. Implications to proinflammatory cytokine-mediated apoptosis in demyelinating diseases. J.Biol.Chem. 273:20354-20362
     Abstract: The present study underlines the importance of reactive oxygen species in cytokine-mediated degradation of sphingomyelin (SM) to ceramide. Treatment of rat primary astrocytes with tumor necrosis factor-alpha (TNF-alpha) or interleukin-1beta led to marked alteration in cellular redox (decrease in intracellular GSH) and rapid degradation of SM to ceramide. Interestingly, pretreatment of astrocytes with N-acetylcysteine (NAC), an antioxidant and efficient thiol source for glutathione, prevented cytokine-induced decrease in GSH and degradation of sphingomyelin to ceramide, whereas treatment of astrocytes with diamide, a thiol-depleting agent, alone caused degradation of SM to ceramide. Moreover, potent activation of SM hydrolysis and ceramide generation were observed by direct addition of an oxidant like hydrogen peroxide or a prooxidant like aminotriazole. Similar to NAC, pyrrolidinedithiocarbamate, another antioxidant, was also found to be a potent inhibitor of cytokine-induced degradation of SM to ceramide indicating that cytokine-induced hydrolysis of sphingomyelin is redox-sensitive. Besides astrocytes, NAC also blocked cytokine-mediated ceramide production in rat primary oligodendrocytes, Microglia, and C6 glial cells. Inhibition of TNF-alpha- and diamide-mediated depletion of GSH, elevation of ceramide level, and DNA fragmentation (apoptosis) in primary oligodendrocytes by NAC, and observed depletion of GSH, elevation of ceramide level, and apoptosis in banked human brains from patients with neuroinflammatory diseases (e.g. X-adrenoleukodystrophy and multiple sclerosis) suggest that the intracellular level of GSH may play a critical role in the regulation of cytokine-induced generation of ceramid