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