Microglia and Alzheimer

1. Asanuma M, Miyazaki I, Tsuji T, Ogawa N (2003) [New aspects of neuroprotective effects of nonsteroidal anti-inflammatory drugs]. Nihon Shinkei Seishin Yakurigaku Zasshi 23:111-119
   Abstract: Nonsteroidal anti-inflammatory drugs (NSAIDs) exert anti-inflammatory, analgesic and antipyretic activities and are involved in the suppression of prostaglandin synthesis by inhibiting cyclooxygenase (COX), a prostaglandin synthesizing enzyme. It has been recently revealed that NSAIDs also possess inhibitory effects on the generating system of nitric oxide radicals and modulating effects on transcription factors and nuclear receptors which are related to inflammatory reactions. Since it has been reported that inflammatory processes are associated with the pathophysiology of several neurodegenerative diseases and that NSAIDs inhibit amyloid beta-protein-induced neurotoxicity to reduce the risk for Alzheimer's disease, a number of studies have been conducted focusing on the neuroprotective effects of NSAIDs. It has been clarified that the drugs exert neuroprotective effects, which are not related to their COX-inhibiting property, on pathophysiology of various neurological disorders. In this article, new aspects of neuroprotective effects of NSAIDs have been reviewed, especially, in Alzheimer's disease and Parkinson's disease, discussing various pharmacological effects of NSAIDs other than their inhibitory action on COX

2. Bard F, Barbour R, Cannon C, Carretto R, Fox M, Games D, Guido T, Hoenow K, Hu K, Johnson-Wood K, Khan K, Kholodenko D, Lee C, Lee M, Motter R, Nguyen M, Reed A, Schenk D, Tang P, Vasquez N, Seubert P, Yednock T (2003) Epitope and isotype specificities of antibodies to beta -amyloid peptide for protection against Alzheimer's disease-like neuropathology. Proc.Natl.Acad.Sci.U.S.A 100:2023-2028
   Abstract: Transgenic PDAPP mice, which express a disease-linked isoform of the human amyloid precursor protein, exhibit CNS pathology that is similar to Alzheimer's disease. In an age-dependent fashion, the mice develop plaques containing beta-amyloid peptide (Abeta) and exhibit neuronal dystrophy and synaptic loss. It has been shown in previous studies that pathology can be prevented and even reversed by immunization of the mice with the Abeta peptide. Similar protection could be achieved by passive administration of some but not all monoclonal antibodies against Abeta. In the current studies we sought to define the optimal antibody response for reducing neuropathology. Immune sera with reactivity against different Abeta epitopes and monoclonal antibodies with different isotypes were examined for efficacy both ex vivo and in vivo. The studies showed that: (i) of the purified or elicited antibodies tested, only antibodies against the N-terminal regions of Abeta were able to invoke plaque clearance; (ii) plaque binding correlated with a clearance response and neuronal protection, whereas the ability of antibodies to capture soluble Abeta was not necessarily correlated with efficacy; (iii) the isotype of the antibody dramatically influenced the degree of plaque clearance and neuronal protection; (iv) high affinity of the antibody for Fc receptors on Microglial cells seemed more important than high affinity for Abeta itself; and (v) complement activation was not required for plaque clearance. These results indicate that antibody Fc-mediated plaque clearance is a highly efficient and effective process for protection against neuropathology in an animal model of Alzheimer's disease

3. Blasko I, Grubeck-Loebenstein B (2003) Role of the immune system in the pathogenesis, prevention and treatment of Alzheimer's disease. Drugs Aging 20:101-113
   Abstract: The dysregulation in the metabolism of beta-amyloid precursor protein and consequent deposition of amyloid-beta (Abeta) has been envisaged as crucial for the development of neurodegeneration in Alzheimer's disease (AD). Amyloid deposition begins 10-20 years before the appearance of clinical dementia. During this time, the brain is confronted with increasing amounts of toxic Abeta peptides and data from the last decade intriguingly suggest that both the innate and the adaptive immune systems may play an important role in the disorder. Innate immunity in the brain is mainly represented by Microglial cells, which phagocytose and degrade Abeta. As the catabolism of Abeta decreases, glial cells become overstimulated and start to produce substances that are toxic to neurons, such as nitric oxide and inflammatory proteins. Pro-inflammatory cytokines can be directly toxic or stimulate Abeta production and increase its cytotoxicity. A therapeutic possibility arises from clinical studies, which demonstrate that nonsteroidal anti-inflammatory drugs (NSAIDs) may delay the onset and slow the progression of AD. Recent data show that in addition to the suppression of inflammatory processes in the brain NSAIDs may decrease the production of Abeta peptides. The role of adaptive immunity lies mainly in the fact that Abeta can be recognised as an antigen. Immunisation with Abeta peptides and peripheral administration of Abeta-specific antibodies both decrease senile plaques and cognitive dysfunction in murine models of AD. A recent trial in humans seems still to be hampered by adverse effects. As adaptive immunity decreases with aging while innate immunity remains intact, immunotherapy for AD will have to be adapted to this situation. Strategies that combine vaccination and inflammatory drug treatment could be considered

4. Chaney MO, Baudry J, Esh C, Childress J, Luehrs DC, Kokjohn TA, Roher AE (2003) A beta, aging, and Alzheimer's disease: a tale, models, and hypotheses. Neurol.Res. 25:581-589
   Abstract: In this paper we explore the potential functional role of the A beta peptides in the context of Alzheimer's disease (AD). We begin by defining the morphology of the amyloid deposits in relation to surrounding glial cells and, more importantly, in relation to the brain vasculature. Amyloid accumulation in the brain's microvasculature causes disturbances in the blood-brain barrier (BBB), and in larger arteries, impairment in control of regional cerebral blood flow due to myocyte degeneration. We postulate that the deposition of vascular amyloid may represent a hydrophobic protein plaster to seal leaks in the BBB, occasionally observed in aging and catastrophically common in AD. The vasoconstrictive activity of A beta may also be related to leaky vessels whereby decreasing the arterial diameter may also help to control breaches in the BBB. The admission of plasma neurotoxic proteins into the brain may be controlled by activation of Microglia elicited by soluble A beta peptides creating a subtle, but permanent brain inflammatory reaction. We also delve into the influence that cholesterol metabolism may have in membrane topology and A beta production, and the close correlations that exist between cardiovascular disease and AD. Finally, we speculate about the possibility of a peripheral source of A beta that may, by crossing the BBB, contribute to the vascular and parenchymal deposits of A beta in the AD brain

5. Chaudhury AR, Gerecke KM, Wyss JM, Morgan DG, Gordon MN, Carroll SL (2003) Neuregulin-1 and erbB4 immunoreactivity is associated with neuritic plaques in Alzheimer disease brain and in a transgenic model of Alzheimer disease. J.Neuropathol.Exp.Neurol. 62:42-54
   Abstract: Neuregulin-1 (NRG-1) regulates developmental neuronal survival and synaptogenesis, astrocytic differentiation, and Microglial activation. Given these NRG-1 actions, we hypothesized that the synaptic loss, gliosis, inflammation, and neuronal death occurring in Alzheimer disease (AD) is associated with altered expression of NRG-1 and its receptors (the erbB2, erbB3, and erbB4 membrane tyrosine kinases). We examined the expression and distribution of NRG-1 and the erbB kinases in the hippocampus of AD patients and cognitively normal controls and in transgenic mice that coexpress AD-associated mutations of the beta amyloid precursor protein (APP(K670N,M671L)) and presenilin-1 (PS1(M146L)). In the hippocampi of both control humans and wild type mice, NRG-1 and the 3 erbB receptors are expressed in distinct cellular compartments of hippocampal neurons. All 4 molecules are associated with neuronal cell bodies, but only NRG-1, erbB2, and erbB4 are present in synapse-rich regions. In AD and in the doubly transgenic mouse, erbB4 is expressed by reactive astrocytes and Microglia surrounding neuritic plaques. In AD brains, Microglia and, to a lesser extent, dystrophic neurites, also upregulate NRG-1 in neuritic plaques, suggesting that autocrine and/or paracrine interactions regulate NRG-1 action within these lesions. NRG-1 and erbB4, as well as erbB2, are similarly associated with neuritic plaques in the doubly transgenic mice. Thus, in AD the hippocampal distribution of NRG-1 and erbB4 is altered. The similarities between the alterations in the expression of NRG-1 and its receptors in human AD and in APP(K670N;M671L)/PS1(M146L) mutant mice suggests that this animal model may be very informative in deciphering the potential role of these molecules in AD

6. Chauhan NB, Siegel GJ (2003) Intracerebroventricular passive immunization with anti-Abeta antibody in Tg2576. J.Neurosci.Res. 74:142-147
   Abstract: Current Alzheimer's disease (AD) research has established the fact that excessive genesis of Abeta derived from amyloidogenic processing of beta-amyloid (Abeta) precursor protein is fundamental to AD pathogenesis. There has been considerable interest in using immunization strategies for clearing excessive Abeta. Studies in animal models of AD have shown that active immunizations or systemic passive immunizations reduced cerebral plaque load and improved behavioral deficits. However, clinical translation of an active immunization strategy was interrupted because of evidence for meningoencephalitis produced in some patients who received Abeta vaccine. Studies in animal models have shown perimicrovascular hemorrhages and inflammation after sustained systemic immunizations in animals with vascular amyloid. In this light, our data showing the effects of a single intracerebroventricular (ICV) injection of anti-Abeta in the Alzheimer's Swedish mutant model Tg2576 are intriguing. We have previously demonstrated that a single ICV injection of anti-Abeta into the third ventricle of 10-month-old Tg2576 mice reduced cerebral plaques, reversed Abeta-induced depletion of presynaptic SNAP-25, and abolished astroglial activation as seen 1 month post-injection (Chauhan and Siegel [2002] J. Neurosci. Res. 69:10-23). The present report demonstrates that a single ICV injection of 10 microg anti-Abeta in 10-month-old Tg2576 mice reduced cerebral plaques, with decreased inflammation at this stage as evidenced by a reduced number of interleukin-1beta-positive Microglia surrounding Congophilic plaques. Moreover, at this particular age, no microhemorrhage was discernible, as evidenced by the absence of hemosiderin deposition after a single ICV injection of anti-Abeta. This is the first report demonstrating absence of microhemorrhage and reduced inflammation after the ICV introduction of anti-Abeta in Tg2576 mice at 10 months of age. These facts indicate that, although invasive, ICV injection of anti-Abeta may be a safer method of vaccination in AD, possibly through reducing the vascular exposure to antibody. Further studies are warranted to determine the lasting effects of a single ICV anti-Abeta injection in animals with and without abundant plaque burden and at older ages

7. Check E (2003) Battle of the mind. Nature 422:370-372

8. Czapiga M, Colton CA (2003) Microglial function in human APOE3 and APOE4 transgenic mice: altered arginine transport. J.Neuroimmunol. 134:44-51
   Abstract: The APOE4 genotype is a known risk factor for Alzheimer's disease (AD) and is associated with poorer outcomes after neuropathological insults. To understand APOE's function, we have examined Microglia, the CNS specific macrophage, in transgenic mice expressing the human APOE3 and APOE4 gene allele. Our data demonstrate that arginine uptake is enhanced in APOE4 Microglia compared to APOE3 Microglia. The increased arginine uptake in APOE4 Tg Microglia is associated with an increased expression of mRNA for cationic amino acid transporter-1 (Cat1), a constuitively expressed member of the arginine selective transport system (the y+ transport system) found in most cells. The macrophage-associated transporter, cationic amino acid transporter 2B (Cat2B) did not demonstrate a change in mRNA expression. This change in Microglial arginine transport suggests a potential impact of the APOE4 gene allele on those biochemical pathways such as NO production or cell proliferation to which arginine contributes

9. Das P, Howard V, Loosbrock N, Dickson D, Murphy MP, Golde TE (2003) Amyloid-beta immunization effectively reduces amyloid deposition in FcRgamma-/- knock-out mice. J.Neurosci. 23:8532-8538
   Abstract: Direct immunization with amyloid beta protein (Abeta) and passive transfer of anti-Abeta antibodies reduce Abeta accumulation and attenuate cognitive deficits in transgenic models of Alzheimer's disease (AD). The reduction in Abeta deposition has been proposed to involve Microglial phagocytosis of Abeta immune complexes via Fc receptors (FcRs). We have examined the efficacy of Abeta immunization in amyloid precursor protein (APP) transgenic mice crossed into FcR-gamma chain knock-out mice (FcRgamma-/-). As might be expected from previous studies on macrophages, phagocytosis of Abeta immune complexes via FcR was completely impaired in Microglia cells isolated from FcRgamma-/- mice. Thus, we immunized APP Tg2576 transgenic mice that were crossed in the FcRgamma-/- background with Abeta1-42 and then analyzed the effect on Abeta accumulation. In APP Tg2576 transgenic mice crossed to FcRgamma-/-, Abeta1-42 immunization significantly attenuated Abeta deposition, as assessed by both biochemical and immunohistological methods. The reduction in Abeta accumulation was equivalent to the reduction in deposition seen in Abeta1-42 immunized, age-matched, FcR-sufficient Tg2576 mice. We conclude that after Abeta immunization, the effects of anti-Abeta antibodies on Abeta deposition in APP Tg2576 transgenic mice are not dependent on FcR-mediated phagocytic events

10. Dodel RC, Hampel H, Du Y (2003) Immunotherapy for Alzheimer's disease. Lancet Neurol. 2:215-220
    Abstract: Recent studies in murine models of Alzheimer's disease (AD) have found that active immunisation with amyloid-beta peptide (Abeta) or passive immunisation with Abeta antibodies can lessen the severity of Abeta-induced neuritic plaque pathology through the activation of Microglia. These antibodies can be detected in the serum and CSF. Whether they slow down or speed up the development and progression of AD has not been determined. Furthermore, the conditions that induce formation of such antibodies are unknown, or how specific they are to AD. However, the evidence suggests at least a potential beneficial role for some features of neuroinflammation in AD. A clinical phase II study of an active immunisation approach with AN1792 was started in 2001, but was recently suspended after some patients developed serious adverse events. These were most likely caused by the activation of the proinflammatory cascade. Immunotherapy approaches represent fascinating ways to test the amyloid hypothesis and may offer genuine opportunities to modify disease progression. This review focuses on immunisation strategies and details of the pathways involved in antibody clearance of Abeta

11. El Khoury JB, Moore KJ, Means TK, Leung J, Terada K, Toft M, Freeman MW, Luster AD (2003) CD36 mediates the innate host response to beta-amyloid. J.Exp.Med. 197:1657-1666
    Abstract: Accumulation of inflammatory Microglia in Alzheimer's senile plaques is a hallmark of the innate response to beta-amyloid fibrils and can initiate and propagate neurodegeneration characteristic of Alzheimer's disease (AD). The molecular mechanism whereby fibrillar beta-amyloid activates the inflammatory response has not been elucidated. CD36, a class B scavenger receptor, is expressed on Microglia in normal and AD brains and binds to beta-amyloid fibrils in vitro. We report here that Microglia and macrophages, isolated from CD36 null mice, had marked reductions in fibrillar beta-amyloid-induced secretion of cytokines, chemokines, and reactive oxygen species. Intraperitoneal and stereotaxic intracerebral injection of fibrillar beta-amyloid in CD36 null mice induced significantly less macrophage and Microglial recruitment into the peritoneum and brain, respectively, than in wild-type mice. Our data reveal that CD36, a major pattern recognition receptor, mediates Microglial and macrophage response to beta-amyloid, and imply that CD36 plays a key role in the proinflammatory events associated with AD

12. Farris W, Mansourian S, Chang Y, Lindsley L, Eckman EA, Frosch MP, Eckman CB, Tanzi RE, Selkoe DJ, Guenette S (2003) Insulin-degrading enzyme regulates the levels of insulin, amyloid beta-protein, and the beta-amyloid precursor protein intracellular domain in vivo. Proc.Natl.Acad.Sci.U.S.A 100:4162-4167
    Abstract: Two substrates of insulin-degrading enzyme (IDE), amyloid beta-protein (Abeta) and insulin, are critically important in the pathogenesis of Alzheimer's disease (AD) and type 2 diabetes mellitus (DM2), respectively. We previously identified IDE as a principal regulator of Abeta levels in neuronal and Microglial cells. A small chromosomal region containing a mutant IDE allele has been associated with hyperinsulinemia and glucose intolerance in a rat model of DM2. Human genetic studies have implicated the IDE region of chromosome 10 in both AD and DM2. To establish whether IDE hypofunction decreases Abeta and insulin degradation in vivo and chronically increases their levels, we characterized mice with homozygous deletions of the IDE gene (IDE --). IDE deficiency resulted in a >50% decrease in Abeta degradation in both brain membrane fractions and primary neuronal cultures and a similar deficit in insulin degradation in liver. The IDE -- mice showed increased cerebral accumulation of endogenous Abeta, a hallmark of AD, and had hyperinsulinemia and glucose intolerance, hallmarks of DM2. Moreover, the mice had elevated levels of the intracellular signaling domain of the beta-amyloid precursor protein, which was recently found to be degraded by IDE in vitro. Together with emerging genetic evidence, our in vivo findings suggest that IDE hypofunction may underlie or contribute to some forms of AD and DM2 and provide a mechanism for the recently recognized association among hyperinsulinemia, diabetes, and AD

13. Frampton M, Harvey RJ, Kirchner V (2003) Propentofylline for dementia. Cochrane.Database.Syst.Rev.CD002853
    Abstract: BACKGROUND: Propentofylline is a novel therapeutic agent for dementia that readily crosses the blood-brain barrier and acts by blocking the uptake of adenosine and inhibiting the enzyme phosphodiesterase. In vitro and in vivo its mechanism of action appears to be twofold; it inhibits the production of free radicals and reduces the activation of Microglial cells. It therefore interacts with the inflammatory processes that are thought to contribute to dementia, and given its mechanism of action is a possible disease modifying agent rather than a purely symptomatic treatment. OBJECTIVES: To determine the clinical efficacy and safety of propentofylline for people with dementia. SEARCH STRATEGY: The trials were identified from a search of the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group on 5 February 2003. Aventis, the manufacturing pharmaceutical company, was asked for data from unpublished studies but declined to enter into correspondence. SELECTION CRITERIA: Unconfounded double-blind randomized controlled trials of propentofylline compared with a placebo or another treatment group. DATA COLLECTION AND ANALYSIS: There were detailed reports of only four of the nine included studies. The efficacy of propentofylline was reviewed for undifferentiated dementia as there were not enough data to attempt a subgroup analysis for the types of dementia. MAIN RESULTS: The following statistically significant treatment effects in favour of propentofylline are reported. Cognition at 3, 6 and 12 months including MMSE at 12 months. [MD 1.2, 95%CI 0.12 to 2.28, P=0.03] Severity of dementia at 3, 6 and 12 months including CGI at 12 months [MD -0.21, 95%CI -0.39 to -0.03, P=0.03]. Activities of Daily Living (NAB) at 6 and 12 months [MD -1.20, 95%CI -2.22 to -0.18, P=0.02]. Global Assessment (CGI) at 3 months [MD -0.48, 95% CI -0.75 to -0.21, P=0.0006], but not at later times. Tolerability There were minimal data on adverse effects and drop-outs. There were a statistically significant treatment effects in favour of placebo at 12 months, for the number of dropouts, [OR=1.43, 95%CI 1.04 to 1.90, P=0.03]. REVIEWER'S CONCLUSIONS: There is limited evidence that propentofylline might benefit cognition, global function and activities of daily living of people with Alzheimer's disease and/or vascular dementia. The meta-analyses reported here are far from satisfactory as a summary of the efficacy of propentofylline, considering the unpublished information on another 1200 patients in randomized trials that exists. Unfortunately Aventis has been unwilling to correspond with the authors, significantly limiting the scope of this review

14. Gomez-Tortosa E, Gonzalo I, Fanjul S, Sainz MJ, Cantarero S, Cemillan C, Yebenes JG, del Ser T (2003) Cerebrospinal fluid markers in dementia with lewy bodies compared with Alzheimer disease. Arch.Neurol. 60:1218-1222
    Abstract: BACKGROUND: Most patients with dementia with Lewy bodies (DLB) exhibit diffuse plaque-only pathology with rare neocortical neurofibrillary tangles (NFTs), as opposed to the widespread cortical neurofibrillary-tau involvement in Alzheimer disease (AD). Another pathological difference is the astrocytic and Microglial inflammatory responses, including release of interleukins (ILs), around the neuritic plaques and NFTs in AD brains that are absent or much lower in DLB. We analyzed cerebrospinal fluid (CSF) markers that reflect the pathological differences between AD and DLB. OBJECTIVE: To determine CSF concentrations of tau, beta-amyloid, IL-1beta, and IL-6 as potential diagnostic clues to distinguish between AD and DLB. METHODS: We measured total tau, beta-amyloid1-42, IL-1beta, and IL-6 levels in CSF samples of 33 patients with probable AD without parkinsonism, 25 patients with all the core features of DLB, and 46 age-matched controls. RESULTS: Patients with AD had significantly higher levels of tau protein than patients with DLB and controls (P<.001). The most efficient cutoff value provided 76% specificity to distinguish AD and DLB cases. Patients with AD and DLB had lower, but not significantly so, beta-amyloid levels than controls. The combination of tau and beta-amyloid levels provided the best sensitivity (84%) and specificity (79%) to differentiate AD vs controls but was worse than tau values alone in discriminating between AD and DLB. Beta-amyloid levels had the best correlation with disease progression in both AD and DLB (P =.01). There were no significant differences in IL-1beta levels among patients with AD, patients with DLB, and controls. Patients with AD and DLB showed slightly, but not significantly, higher IL-6 levels than controls. CONCLUSIONS: The tau levels in CSF may contribute to the clinical distinction between AD and DLB. Beta-amyloid CSF levels are similar in both dementia disorders and reflect disease progression better than tau levels. Interleukin CSF concentrations do not distinguish between AD and DLB

15. Hartig W, Paulke BR, Varga C, Seeger J, Harkany T, Kacza J (2003) Electron microscopic analysis of nanoparticles delivering thioflavin-T after intrahippocampal injection in mouse: implications for targeting beta-amyloid in Alzheimer's disease. Neurosci.Lett. 338:174-176
    Abstract: Prevention of beta-amyloid (Abeta) production, aggregation and formation of Abeta deposits is a key pharmacological target in Alzheimer's disease. The passage of Abeta-binding compounds through the blood-brain barrier is often hampered for free ligands, whereas it is enhanced by drug encapsulation in nanoparticles. Here, we describe the preparation and characterization of polymeric carriers containing thioflavin-T as a marker for fibrillar Abeta. This study is then focused on electron microscopic analyses of thioflavin-T after injection of thioflavin-T-containing nanoparticles into the mouse hippocampus. Therefore, the photoconversion of fluorescent thioflavin-T as model drug was performed in tissues fixed 3 days post-injection. Thioflavin-T delivered from nanospheres was predominantly found in neurons and Microglia. Our data suggest that drugs delivered by nanoparticles might target Abeta in the brain

16. Hartlage-Rubsamen M, Zeitschel U, Apelt J, Gartner U, Franke H, Stahl T, Gunther A, Schliebs R, Penkowa M, Bigl V, Rossner S (2003) Astrocytic expression of the Alzheimer's disease beta-secretase (BACE1) is stimulus-dependent. Glia 41:169-179
    Abstract: The beta-site APP-cleaving enzyme (BACE1) is a prerequisite for the generation of beta-amyloid peptides, which give rise to cerebrovascular and parenchymal beta-amyloid deposits in the brain of Alzheimer's disease patients. BACE1 is neuronally expressed in the brains of humans and experimental animals such as mice and rats. In addition, we have recently shown that BACE1 protein is expressed by reactive astrocytes in close proximity to beta-amyloid plaques in the brains of aged transgenic Tg2576 mice that overexpress human amyloid precursor protein carrying the double mutation K670N-M671L. To address the question whether astrocytic BACE1 expression is an event specifically triggered by beta-amyloid plaques or whether glial cell activation by other mechanisms also induces BACE1 expression, we used six different experimental strategies to activate brain glial cells acutely or chronically. Brain sections were processed for the expression of BACE1 and glial markers by double immunofluorescence labeling and evaluated by confocal laser scanning microscopy. There was no detectable expression of BACE1 protein by activated Microglial cells of the ameboid or ramified phenotype in any of the lesion paradigms studied. In contrast, BACE1 expression by reactive astrocytes was evident in chronic but not in acute models of gliosis. Additionally, we observed BACE1-immunoreactive astrocytes in proximity to beta-amyloid plaques in the brains of aged Tg2576 mice and Alzheimer's disease patients

17. Holmes C, El Okl M, Williams AL, Cunningham C, Wilcockson D, Perry VH (2003) Systemic infection, interleukin 1beta, and cognitive decline in Alzheimer's disease. J.Neurol.Neurosurg.Psychiatry 74:788-789
    Abstract: Activated Microglia, the resident macrophages of the brain, are a feature of Alzheimer's disease. Animal models suggest that when activated Microglia are further activated by a subsequent systemic infection this results in significantly raised levels of interleukin 1beta within the CNS, which may in turn potentiate neurodegeneration. This prospective pilot study in Alzheimer's disease subjects showed that cognitive function can be impaired for at least two months after the resolution of a systemic infection and that cognitive impairment is preceded by raised serum levels of interleukin 1beta. These relations were not confounded by the presence of any subsequent systemic infection or by baseline cognitive scores. Further research is needed to determine whether recurrent systemic infections drive cognitive decline in Alzheimer's disease subjects through a cytokine mediated pathway

18. Jayakumar R, Kusiak JW, Chrest FJ, Demehin AA, Murali J, Wersto RP, Nagababu E, Ravi L, Rifkind JM (2003) Red cell perturbations by amyloid beta-protein. Biochim.Biophys.Acta 1622:20-28
    Abstract: Amyloid beta-protein (A beta) accumulation in brain is thought to be important in causing the neuropathology of Alzheimer's disease (AD). A beta interactions with both neurons and Microglial cells play key roles in AD. Since vascular deposition of A beta is also implicated in AD, the interaction of red cells with these toxic aggregates gains importance. However, the effects of A beta interactions with red blood cells are less well understood. Synthetic amyloid beta-protein (1-40) was labeled with biotin and preincubated at 37 degrees C for 4, 14 and 72 h to produce fibrils. Flow cytometry was used to study the binding of these fibrils to red cells. The amyloid fibrils had a high affinity for the red cell with increased binding for the larger fibrils produced by longer preincubation. Bovine serum albumin (BSA) did not reverse the binding, but actually resulted in a more efficient binding of the A beta fibrils to the red cells. The interaction of A beta with red cells increased the mean cell volume and caused the cells to become more spherical. This effect was greater for the longer fibrils. At the same time the interaction of A beta with red cells produced an increase in their fluorescence measured after 16-h incubation at 37 degrees C. This increase in fluorescence is attributed to the formation of fluorescent heme degradation products. The effect of prior hemoglobin oxidation, catalase inhibition and glutathione peroxidase inhibition indicated that the amyloid-induced oxidative damage to the red cell involved hydrogen peroxide-induced heme degradation. These results suggest that amyloid interactions with the red cell may contribute to the pathology of AD

19. Katsuse O, Iseki E, Kosaka K (2003) Immunohistochemical study of the expression of cytokines and nitric oxide synthases in brains of patients with dementia with Lewy bodies. Neuropathology. 23:9-15
    Abstract: Regional expression of cytokines (IL-1alpha, TNF-alpha), inducible nitric oxide synthase (iNOS) and neuronal NOS (nNOS) was immunohistochemically investigated in the brains of patients with dementia with Lewy bodies (DLB), compared with those of patients with Alzheimer's disease (AD) and non-demented elderly persons. It has been reported that inflammatory responses by cytokines and oxygen free radicals such as nitric oxide (NO) are associated with damaged neurons, degenerative neurites or amyloid deposits in AD brains. In the present study, overexpression of IL-1alpha, TNF-alpha and iNOS was demonstrated in the amygdala, hippocampus, entorhinal and insular cortices of DLB brains, which are pathologically the most vulnerable regions in DLB brains as well as AD brains. In addition, some Lewy body (LB)-bearing neurons were involved by the processes of IL-1alpha- and TNF-alpha-positive Microglia, and most extracellular LB were associated with the processes of TNF-alpha- and iNOS-positive astroglia. Glial involvement was also found around neuritic plaques and extracellular neurofibrillary tangles. In contrast, the expression of nNOS was reduced in the amygdala of DLB brains showing severe Lewy pathology. These findings suggest that cytokines and NO are significantly implicated in neuronal damage and death including LB formation in DLB brains

20. Kitamura Y, Nomura Y (2003) Stress proteins and glial functions: possible therapeutic targets for neurodegenerative disorders. Pharmacol.Ther. 97:35-53
    Abstract: Recent findings suggest that unfolded or misfolded proteins participate in the pathology of several neurodegenerative disorders, such as Alzheimer's disease and Parkinson's disease. Usually, several stress proteins and glial cells act as intracellular molecular chaperones and show chaperoning neuronal function, respectively. In the brains of patients with neurodegenerative disorders, however, stress proteins are expressed and frequently associated with protein aggregates, and glial cells are activated around degenerative regions. In addition, several stress proteins and glial cells may also regulate neuronal cell death and loss. Therefore, some types of stress proteins and glial cells are considered to be neuroprotective targets. We summarize the current findings regarding the neuroprotective effects of stress proteins and glial cells, and discuss the possibility of using this knowledge to develop new therapeutic strategies to treat neurodegeneration

21. Lambert JC, Luedecking-Zimmer E, Merrot S, Hayes A, Thaker U, Desai P, Houzet A, Hermant X, Cottel D, Pritchard A, Iwatsubo T, Pasquier F, Frigard B, Conneally PM, Chartier-Harlin MC, DeKosky ST, Lendon C, Mann D, Kamboh MI, Amouyel P (2003) Association of 3'-UTR polymorphisms of the oxidised LDL receptor 1 (OLR1) gene with Alzheimer's disease. J.Med.Genet. 40:424-430
    Abstract: Although possession of the epsilon 4 allele of the apolipoprotein E gene appears to be an important biological marker for Alzheimer's disease (AD) susceptibility, strong evidence indicates that at least one additional risk gene exists on chromosome 12. Here, we describe an association of the 3'-UTR +1073 C/T polymorphism of the OLR1 (oxidised LDL receptor 1) on chromosome 12 with AD in French sporadic (589 cases and 663 controls) and American familial (230 affected sibs and 143 unaffected sibs) populations. The age and sex adjusted odds ratio between the CC+CT genotypes versus the TT genotypes was 1.56 (p=0.001) in the French sample and 1.92 (p=0.02) in the American sample. Furthermore, we have discovered a new T/A polymorphism two bases upstream of the +1073 C/T polymorphism. This +1071 T/A polymorphism was not associated with the disease, although it may weakly modulate the impact of the +1073 C/T polymorphism. Using 3'-UTR sequence probes, we have observed specific DNA protein binding with nuclear proteins from lymphocyte, astrocytoma, and neuroblastoma cell lines, but not from the Microglia cell line. This binding was modified by both the +1071 T/A and +1073 C/T polymorphisms. In addition, a trend was observed between the presence or absence of the +1073 C allele and the level of astrocytic activation in the brain of AD cases. However, Abeta(40), Abeta(42), Abeta total, and Tau loads or the level of Microglial cell activation were not modulated by the 3'-UTR OLR1 polymorphisms. Finally, we assessed the impact of these polymorphisms on the level of OLR1 expression in lymphocytes from AD cases compared with controls. The OLR1 expression was significantly lower in AD cases bearing the CC and CT genotypes compared with controls with the same genotypes. In conclusion, our data suggest that genetic variation in the OLR1 gene may modify the risk of AD

22. Lesne S, Docagne F, Gabriel C, Liot G, Lahiri DK, Buee L, Plawinski L, Delacourte A, MacKenzie ET, Buisson A, Vivien D (2003) Transforming growth factor-beta 1 potentiates amyloid-beta generation in astrocytes and in transgenic mice. J.Biol.Chem. 278:18408-18418
    Abstract: Accumulation of the amyloid-beta peptide (Abeta) in the brain is crucial for development of Alzheimer's disease. Expression of transforming growth factor-beta1 (TGF-beta1), an immunosuppressive cytokine, has been correlated in vivo with Abeta accumulation in transgenic mice and recently with Abeta clearance by activated Microglia. Here, we demonstrate that TGF-beta1 drives the production of Abeta40/42 by astrocytes leading to Abeta production in TGF-beta1 transgenic mice. First, TGF-beta1 induces the overexpression of the amyloid precursor protein (APP) in astrocytes but not in neurons, involving a highly conserved TGF-beta1-responsive element in the 5'-untranslated region (+54/+74) of the APP promoter. Second, we demonstrated an increased release of soluble APP-beta which led to TGF-beta1-induced Abeta generation in both murine and human astrocytes. These results demonstrate that TGF-beta1 potentiates Abeta production in human astrocytes and may enhance the formation of plaques burden in the brain of Alzheimer's disease patients

23. Lorenzl S, Albers DS, Relkin N, Ngyuen T, Hilgenberg SL, Chirichigno J, Cudkowicz ME, Beal MF (2003) Increased plasma levels of matrix metalloproteinase-9 in patients with Alzheimer's disease. Neurochem.Int. 43:191-196
    Abstract: Matrix metalloproteinases (MMPs) may play a role in the pathophysiology of Alzheimer's disease (AD). MMP-9 and tissue inhibitors of metalloproteinases (TIMPs) are elevated in postmortem brain tissue of AD patients. MMPs and TIMPs are found in neurons, Microglia, vascular endothelial cells and leukocytes. The aim of this study was to determine whether circulating levels of MMP-2, MMP-9, TIMP-1 and TIMP-2 are elevated in the plasma of AD patients. We compared AD patients to age- and gender-matched controls as well as to Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS) patients. There was constitutive expression of gelatinase A (MMP-2), and gelatinase B (MMP-9), in all the samples as shown by zymographic analysis. Levels of MMP-9 were significantly (P=0.003) elevated in the plasma of AD patients as compared to controls. Plasma levels of MMP-2, TIMP-1 and TIMP-2 were unchanged. There were no significant changes of MMP-2, MMP-9, TIMP-1 and TIMP-2 levels in PD and ALS samples. TIMP-1 and TIMP-2 were significantly correlated with MMP-9 in the AD patients. ApoE genotyping of plasma samples showed that levels of MMP-2, TIMP-1 and TIMP-2 and MMP-9 were not significantly different between the ApoE subgroups. These findings indicate that circulating levels of MMP-9 are increased in AD and may contribute to disease pathology

24. Luca M, Chavez-Ross A, Edelstein-Keshet L, Mogilner A (2003) Chemotactic signaling, Microglia, and Alzheimer's disease senile plaques: is there a connection? Bull.Math.Biol. 65:693-730
    Abstract: Chemotactic cells known as Microglia are involved in the inflammation associated with pathology in Alzheimer's disease (AD). We investigate conditions that lead to aggregation of Microglia and formation of local accumulations of chemicals observed in AD senile plaques. We develop a model for chemotaxis in response to a combination of chemoattractant and chemorepellent signaling chemicals. Linear stability analysis and numerical simulations of the model predict that periodic patterns in cell and chemical distributions can evolve under local attraction, long-ranged repulsion, and other constraints on concentrations and diffusion coefficients of the chemotactic signals. Using biological parameters from the literature, we compare and discuss the applicability of this model to actual processes in AD

25. Luth HJ, Apelt J, Ihunwo AO, Arendt T, Schliebs R (2003) Degeneration of beta-amyloid-associated cholinergic structures in transgenic APP SW mice. Brain Res. 977:16-22
    Abstract: Cholinergic dysfunction is a consistent feature of Alzheimer's disease, and the interrelationship between beta-amyloid deposits, inflammation and early cholinergic cell loss is still not fully understood. To characterize the mechanisms by which beta-amyloid and pro-inflammatory cytokines may exert specific degenerating actions on cholinergic cells ultrastructural investigations by electron microscopy were performed in brain sections from transgenic Tg2576 mice that express the Swedish double mutation of the human amyloid precursor protein and progressively develop beta-amyloid plaques during aging. Both light and electron microscopical investigations of the cerebral cortex of 19-month-old transgenic mice revealed a number of pathological tissue responses in close proximity of beta-amyloid plaques, such as activated Microglia, astroglial proliferation, increased number of fibrous astrocytes, brain edema, degeneration of nerve cells, dendrites and axon terminals. Ultrastructural detection of choline acetyl transferase (ChAT)-immunostaining in cerebral cortical sections of transgenic mice clearly demonstrated degeneration of ChAT-immunoreactive fibres in the environment of beta-amyloid plaques and activated glial cells suggesting a role of beta-amyloid and/or inflammation in specific degeneration of cholinergic synaptic structures

26. McGeer EG, McGeer PL (2003) Inflammatory processes in Alzheimer's disease. Prog.Neuropsychopharmacol.Biol.Psychiatry 27:741-749
    Abstract: Neuroinflammation is a characteristic of pathologically affected tissue in several neurodegenerative disorders. These changes are particularly observed in affected brain areas of Alzheimer's disease (AD) cases. They include an accumulation of large numbers of activated Microglia and astrocytes as well as small numbers of T-cells, mostly adhering to postcapillary venules. Accompanying biochemical alterations include the appearance or up-regulation of numerous molecules characteristic of inflammation and free radical attack. Particularly important may be the complement proteins, acute phase reactants and inflammatory cytokines. These brain phenomena combined with epidemiological evidence of a protective effect of antiinflammatory agents suggest that such agents may have a role to play in treating the disease

27. Melchor JP, Pawlak R, Strickland S (2003) The tissue plasminogen activator-plasminogen proteolytic cascade accelerates amyloid-beta (Abeta) degradation and inhibits Abeta-induced neurodegeneration. J.Neurosci. 23:8867-8871
    Abstract: Accumulation of the amyloid-beta (Abeta) peptide depends on both its generation and clearance. To better define clearance pathways, we have evaluated the role of the tissue plasminogen activator (tPA)-plasmin system in Abeta degradation in vivo. In two different mouse models of Alzheimer's disease, chronically elevated Abeta peptide in the brain correlates with the upregulation of plasminogen activator inhibitor-1 (PAI-1) and inhibition of the tPA-plasmin system. In addition, Abeta injected into the hippocampus of mice lacking either tPA or plasminogen persists, inducing PAI-1 expression and causing activation of Microglial cells and neuronal damage. Conversely, Abeta injected into wild-type mice is rapidly cleared and does not cause neuronal degeneration. Thus, the tPA-plasmin proteolytic cascade aids in the clearance of Abeta, and reduced activity of this system may contribute to the progression of Alzheimer's disease

28. Minnasch P, Yamamoto Y, Ohkubo I, Nishi K (2003) Demonstration of puromycin-sensitive alanyl aminopeptidase in Alzheimer disease brain. Leg.Med.(Tokyo) 5 Suppl 1:S285-S287
    Abstract: Puromycin-sensitive alanyl aminopeptidase (PSA, EC 3.4.11.14) is a member of the ubiquitous aminopeptidase family, which cleaves N-terminal amino acids from proteins. PSA is suggested to function as a trimming protease in the MHC class I pathway, which is activated in brains of Alzheimer disease (AD). We examined the immunohistochemical localization of PSA in brains of AD and control cases using a rabbit anti-PSA. In the control cases, the antiserum revealed staining in a few glial cells and blood vessels. In AD brain, however, intensely stained cells were found richly in the cerebral cortex. Double immunofluorescence studies confirmed that PSA-positive cells were reactive Microglia. Such PSA-positive reactive Microglia tended to locate in and around senile plaques and were sometimes observed to associate with neurons containing neurofibillary tangles. The present result indicates that reactive Microglia express PSA-immunoreactive molecules, probably in association with the pathological conditions of AD

29. Monsonego A, Weiner HL (2003) Immunotherapeutic approaches to Alzheimer's disease. Science 302:834-838
    Abstract: Although neurodegenerative diseases such as Alzheimer's disease are not classically considered mediated by inflammation or the immune system, in some instances the immune system may play an important role in the degenerative process. Furthermore, it has become clear that the immune system itself may have beneficial effects in nervous system diseases considered neurodegenerative. Immunotherapeutic approaches designed to induce a humoral immune response have recently been developed for the treatment of Alzheimer's disease. These studies have led to human trials that resulted in both beneficial and adverse effects. In animal models, it has also been shown that immunotherapy designed to induce a cellular immune response may be of benefit in central nervous system injury, although T cells may have either a beneficial or detrimental effect depending on the type of T cell response induced. These areas provide a new avenue for exploring immune system-based therapy of neurodegenerative diseases and will be discussed here with a primary focus on Alzheimer's disease. We will also discuss how these approaches affect Microglia activation, which plays a key role in therapy of such diseases

30. Morgan D (2003) Antibody therapy for Alzheimer's disease. Expert.Rev.Vaccines. 2:53-59
    Abstract: The economic, social and emotional impact of Alzheimer's dementia is increasing dramatically as greater numbers live to advanced ages. The dearth of effective therapies has led to innovative approaches to treat the disease. This review summarizes the rationale, progress and setbacks regarding the use of antibody-based therapies to treat Alzheimer's disease and discusses future directions for this approach in Alzheimer's and other disorders

31. Munch G, Gasic-Milenkovic J, Dukic-Stefanovic S, Kuhla B, Heinrich K, Riederer P, Huttunen HJ, Founds H, Sajithlal G (2003) Microglial activation induces cell death, inhibits neurite outgrowth and causes neurite retraction of differentiated neuroblastoma cells. Exp.Brain Res. 150:1-8
    Abstract: Activation of glial cells has been proposed to contribute to neuronal dysfunction and neuronal cell death in Alzheimer's disease. In this study, we attempt to determine some of the effects of secreted factors from activated murine N-11 Microglia on viability and morphology of neurons using the differentiated neuroblastoma cell line Neuro2a. Microglia were activated either by lipopolysaccharide (LPS), bacterial cell wall proteoglycans, or advanced glycation endproducts (AGEs), protein-bound sugar oxidation products. At high LPS or AGE concentrations, conditioned medium from Microglia caused neuronal cell death in a dose-dependent manner. At sublethal LPS or AGE concentrations, conditioned media inhibited retinoic acid-induced neurite outgrowth and stimulated retraction of already extended neurites. Among the many possible secreted factors, the contribution of NO or NO metabolites in the cytotoxicity of conditioned medium was investigated. Cell death and changes in neurite morphology were partly reduced when NO production was inhibited by nitric oxide synthase inhibitors. The results suggest that even in the absence of significant cell death, inflammatory processes, which are partly transmitted via NO metabolites, may affect intrinsic functions of neurons such as neurite extension that are essential components of neuronal morphology and thus may contribute to degenerative changes in Alzheimer's disease

32. Murphy A, Sunohara JR, Sundaram M, Ridgway ND, McMaster CR, Cook HW, Byers DM (2003) Induction of protein kinase C substrates, Myristoylated alanine-rich C kinase substrate (MARCKS) and MARCKS-related protein (MRP), by amyloid beta-protein in mouse BV-2 Microglial cells. Neurosci.Lett. 347:9-12
    Abstract: Microglial activation by amyloid beta-protein in senile plaques contributes to neurodegeneration in Alzheimer disease. In BV-2 Microglial cells, amyloid beta-protein 1-40 (Abeta 1-40) elicited a dose-dependent increase (3-4 fold) of Myristoylated alanine-rich C kinase substrate (MARCKS) and MARCKS-related protein (MRP), two protein kinase C substrates implicated in membrane-cytoskeletal alterations underlying Microglial adhesion, migration, secretion, and phagocytosis. Neither MARCKS nor MRP was induced by the amyloid fragment Abeta 25-35, although both Abeta 1-40 and Abeta 25-35 caused extensive aggregation of BV-2 cells. Interferon-gamma synergistically enhanced the induction by Abeta 1-40 of inducible nitric oxide synthase, but not MARCKS or MRP. Our results suggest that MARCKS and MRP may play important roles in Microglia activated by amyloid peptides

33. Nicoll JA, Wilkinson D, Holmes C, Steart P, Markham H, Weller RO (2003) Neuropathology of human Alzheimer disease after immunization with amyloid-beta peptide: a case report. Nat.Med. 9:448-452
    Abstract: Amyloid-beta peptide (Abeta) has a key role in the pathogenesis of Alzheimer disease (AD). Immunization with Abeta in a transgenic mouse model of AD reduces both age-related accumulation of Abeta in the brain and associated cognitive impairment. Here we present the first analysis of human neuropathology after immunization with Abeta (AN-1792). Comparison with unimmunized cases of AD (n = 7) revealed the following unusual features in the immunized case, despite diagnostic neuropathological features of AD: (i) there were extensive areas of neocortex with very few Abeta plaques; (ii) those areas of cortex that were devoid of Abeta plaques contained densities of tangles, neuropil threads and cerebral amyloid angiopathy (CAA) similar to unimmunized AD, but lacked plaque-associated dystrophic neurites and astrocyte clusters; (iii) in some regions devoid of plaques, Abeta-immunoreactivity was associated with Microglia; (iv) T-lymphocyte meningoencephalitis was present; and (v) cerebral white matter showed infiltration by macrophages. Findings (i)-(iii) strongly resemble the changes seen after Abeta immunotherapy in mouse models of AD and suggest that the immune response generated against the peptide elicited clearance of Abeta plaques in this patient. The T-lymphocyte meningoencephalitis is likely to correspond to the side effect seen in some other patients who received AN-1792 (refs. 7-9)

34. Ophir G, Meilin S, Efrati M, Chapman J, Karussis D, Roses A, Michaelson DM (2003) Human apoE3 but not apoE4 rescues impaired astrocyte activation in apoE null mice. Neurobiol.Dis. 12:56-64
    Abstract: The allele E4 of apolipoprotein E (apoE) is an important risk factor for Alzheimer's disease (AD) and the chronic brain inflammation which is associated with AD is more pronounced in subjects who carry this allele. In the present study, we employed mice transgenic for the human apoE isoforms apoE3 or apoE4 on a null mouse apoE background and intracerebroventricular injection of LPS to investigate the possibility that the regulation of brain inflammation is affected by the apoE genotype. LPS treatment of control mice resulted in activation of brain astrocytes and Microglia whose extent decreased with age. LPS treatment of 6-month-old apoE transgenic and control mice resulted in marked activation of brain astrocytes in the control and apoE3 transgenic mice but had no effect on astrogliosis of age-matched apoE-deficient and apoE4 transgenic mice. In contrast, there were no significant differences between the levels of activated Microglia of the apoE3 and apoE4 transgenic mice following LPS treatment. Immunoblot assays revealed that the apoE4 and apoE3 transgenic mice had the same levels of brain apoE, which were similarly increased following LPS treatment. These results show that LPS-induced astrogliosis in apoE transgenic mice is regulated isoform-specifically by apoE3 and not by apoE4 and suggest that similar mechanisms may mediate the phenotypic expression of the apoE4 genotype in AD and in other neurodegenerative diseases

35. Pahnke J, Walker LC, Schroeder E, Vogelgesang S, Stausske D, Walther R, Warzok RW (2003) Cerebral beta-amyloid deposition is augmented by the -491AA promoter polymorphism in non-demented elderly individuals bearing the apolipoprotein E epsilon4 allele. Acta Neuropathol.(Berl) 105:25-29
    Abstract: The apolipoprotein E epsilon4 allele (APOE, gene; apoE, protein) is widely accepted as a risk factor for Alzheimer's disease (AD). Our previous studies found that APOEepsilon4 promotes AD pathogenesis by fostering the early deposition of the amyloidogenic peptide Abeta in the aging brain. Recent reports suggest that polymorphisms in the upstream promoter region of APOE differentially affect the production of apoE and also may have an important influence on the probability of developing AD. In this study, we asked whether APOE promoter -491 (A/T) variants interact with APOE polymorphisms to modulate the degree of beta-amyloid- and tau-related pathology in the medial temporal lobe of the non-demented elderly. Our results confirm that APOEepsilon4 is associated with increased formation of senile plaques, cerebrovascular amyloid, and neurofibrillary tangles in the medial temporal lobe. We also found that homozygosity for A at position -491 of the APOE promoter (-491AA) correlates with increased Abeta17-24 and Abeta42 deposition in APOEepsilon4-positive cases, but not in cases lacking the epsilon4 allele. In comparison, Abeta burden is significantly less in epsilon4 carriers with the -491AT and -491TT promoter allelotypes. There was no effect of -491 polymorphisms on Abeta40 deposition (which is relatively sparse in the non-demented elderly), on the number of activated Microglia, or on the amount of neurofibrillary tangles. We conclude that the amyloidogenic effects of apoE4 are exacerbated by polymorphisms in the APOE promoter that enhance apoE production

36. Parvathenani LK, Tertyshnikova S, Greco CR, Roberts SB, Robertson B, Posmantur R (2003) P2X7 mediates superoxide production in primary Microglia and is up-regulated in a transgenic mouse model of Alzheimer's disease. J.Biol.Chem. 278:13309-13317
    Abstract: Primary rat Microglia stimulated with either ATP or 2'- and 3'-O-(4-benzoylbenzoyl)-ATP (BzATP) release copious amounts of superoxide (O(2)(-)*). ATP and BzATP stimulate O(2)(-)* production through purinergic receptors, primarily the P2X(7) receptor. O(2)(-)* is produced through the activation of the NADPH oxidase. Although both p42/44 MAPK and p38 MAPK were activated rapidly in cells stimulated with BzATP, only pharmacological inhibition of p38 MAPK attenuated O(2)(-)* production. Furthermore, an inhibitor of phosphatidylinositol 3-kinase attenuated O(2)(-)* production to a greater extent than an inhibitor of p38 MAPK. Both ATP and BzATP stimulated Microglia-induced cortical cell death indicating this pathway may contribute to neurodegeneration. Consistent with this hypothesis, P2X(7) receptor was specifically up-regulated around beta-amyloid plaques in a mouse model of Alzheimer's disease (Tg2576)

37. Qiu Z, Gruol DL (2003) Interleukin-6, beta-amyloid peptide and NMDA interactions in rat cortical neurons. J.Neuroimmunol. 139:51-57
    Abstract: Neuronal damage in Alzheimer's disease (AD) is thought to involve direct toxicity of beta-amyloid peptide (Abeta) and excitotoxicity involving NMDA receptors (NMDARs) and altered Ca(2+) dynamics. Inflammation agents produced by Microglia or astrocytes and associated with senile plaques such as the cytokine interleukin-6 (IL-6) could also contribute. To investigate this possibility, neuronal damage (lactate dehydrogenase assay, LDH, assay) was measured in cultures of rodent cortical neurons chronically treated with IL-6, Abeta or Abeta plus IL-6 and acutely treated with NMDA. Both Abeta and NMDA produced neuronal damage and this effect was larger with combined treatment. IL-6 did not produce significant neuronal damage but the largest neuronal damage was observed in cultures exposed to all three factors. IL-6 and Abeta enhanced Ca(2+) responses to NMDA and combined treatment produced the largest effect. These results are consistent with a role for interactions between Abeta, NMDA and IL-6 in the neuronal loss in AD

38. Rangon CM, Haik S, Faucheux BA, Metz-Boutigue MH, Fierville F, Fuchs JP, Hauw JJ, Aunis D (2003) Different chromogranin immunoreactivity between prion and a-beta amyloid plaque. Neuroreport 14:755-758
    Abstract: Brain lesions in Creutzfeldt-Jakob disease (CJD) include spongiform change, neuronal loss, amyloid plaques, astrogliosis and Microglial activation. Microglia are thought to play a key role in prion-induced neurodegeneration. However, the intermediate molecules supporting relationships between neurons and Microglia are still unknown. Chromogranins (Cg) are soluble glycophosphoproteins that can activate Microglial cells leading to a neurotoxic phenotype. The immunoreactive patterns of CgA and CgB were investigated in CJD and compared to those observed in Alzheimer's disease. We found that CgB, but not CgA, immunoreactivity was selectively associated with prion protein deposits, whereas CgA was only seen in Abeta plaques. This suggests a specific influence of the constitutive amyloid protein on chromogranin secretion and a role of CgB in the CJD neurodegenerative process

39. Scali C, Giovannini MG, Prosperi C, Bellucci A, Pepeu G, Casamenti F (2003) The selective cyclooxygenase-2 inhibitor rofecoxib suppresses brain inflammation and protects cholinergic neurons from excitotoxic degeneration in vivo. Neuroscience 117:909-919
    Abstract: Brain inflammatory processes underlie the pathogenesis of Alzheimer's disease, and non-steroidal anti-inflammatory drugs have a protective effect in the disease. The aim of this work was to study in vivo whether attenuation of brain inflammatory response to excitotoxic insult by the selective cyclooxygenase-2 inhibitor, rofecoxib, may prevent neurodegeneration, as a contribution to a better understanding of the role inflammation plays in the pathology of Alzheimer's disease. We investigated, by immunohistochemical methods, glia reaction, the activation of p38 mitogen-activated protein kinase (p38MAPK) pathway with an antibody selective for the phosphorylated form of the enzyme and the number of choline acetyltransferase-positive neurons and, by in vivo microdialysis, cortical extracellular levels of acetylcholine following the injection of quisqualic acid into the right nucleus basalis of adult rats. Seven days after injection, a marked reduction in the number of choline acetyltransferase-positive neurons was found, along with an intense glia reaction, selective activation of p38MAPK at the injection site and a significant decrease in the extracellular levels of acetylcholine in the cortex ipsilateral to the injection site. The loss of cholinergic neurons persisted for at least up to 28 days. Rofecoxib (3 mg/kg/day, starting 1 h prior to injection of quisqualic acid) treatment for 7 days significantly attenuated glia activation and prevented the loss of choline acetyltransferase-positive cells and a decrease in cortical acetylcholine release. The prevention of cholinergic cell loss by rofecoxib occurred concomitantly with the inhibition of p38MAPK phosphorylation. Our findings suggest an important role of brain inflammatory reaction in cholinergic degeneration and demonstrate a neuroprotective effect of rofecoxib, presumably mediated through the inhibition of p38MAPK phosphorylation

40. Sheng JG, Bora SH, Xu G, Borchelt DR, Price DL, Koliatsos VE (2003) Lipopolysaccharide-induced-neuroinflammation increases intracellular accumulation of amyloid precursor protein and amyloid beta peptide in APPswe transgenic mice. Neurobiol.Dis. 14:133-145
    Abstract: The present study was designed to examine whether brain inflammation caused by systemic administration of lipopolysaccharides (LPS) alters the expression/processing of amyloid precursor protein (APP) and increases the generation of amyloid beta peptide (Abeta). APPswe transgenic (Tg) mice were treated with either LPS or phosphate-buffered saline (PBS). In LPS-treated APPswe mice, Abeta1-40/42 was 3-fold and APP was 1.8-fold higher than those in PBS-treated mice (P < 0.05) by ELISA, Western blots and immunoprecipitation-mass spectrometry (IP-MS) ProteinChip analysis. Numbers of Abeta- and APP-immunoreactive neurons (Abeta(+) and APP(+) neurons) increased significantly in LPS-treated APPswe mice; APP(+) and Abeta(+) neurons in neocortex were associated with an increased number of F4/80-immunoreactive Microglia (F4/80(+) Microglia) in their anatomical environment. Our findings demonstrate that experimental neuroinflammation increases APP expression/processing and causes intracellular accumulation of Abeta. It remains to be seen whether such events can cause neuronal dysfunction/degeneration and, with time, lead to extracellular Abeta deposits, as they occur in Alzheimer's disease

41. Su Y, Ganea D, Peng X, Jonakait GM (2003) Galanin down-regulates Microglial tumor necrosis factor-alpha production by a post-transcriptional mechanism. J.Neuroimmunol. 134:52-60
    Abstract: The neuropeptide galanin (GAL) is up-regulated following neuronal axotomy or inflammation. Since other neuropeptides act as immunomodulatory agents, we sought to determine whether GAL might affect the murine Microglial cell line BV2, which expresses the GAL2 receptor. Even at very low concentrations, GAL inhibited tumor necrosis factor-alpha (TNF alpha) release but not TNF alpha mRNA levels in LPS-stimulated BV2 cells. Northern blot analysis showed that GAL inhibited the addition of a poly(A) tail, and stability assays showed that it also destabilized TNF alpha mRNA. Thus, GAL inhibits TNF alpha production by a post-transcriptional mechanism that both prevents the efficient addition of the poly(A) tail and accelerates TNF alpha mRNA degradation

42. Takata K, Kitamura Y, Kakimura J, Shibagaki K, Tsuchiya D, Taniguchi T, Smith MA, Perry G, Shimohama S (2003) Role of high mobility group protein-1 (HMG1) in amyloid-beta homeostasis. Biochem.Biophys.Res.Commun. 301:699-703
    Abstract: In Alzheimer's disease (AD), fibrillar amyloid-beta (Abeta) peptides form senile plaques associated with activated Microglia. Recent studies have indicated that Microglial Abeta clearance is facilitated by several activators such as transforming growth factor-beta1 (TGF-beta1). The relationship between Microglia and Abeta formation and deposition is still unclear. In the present study, high mobility group protein-1 (HMG1) inhibited the Microglial uptake of Abeta (1-42) in the presence and absence of TGF-beta1. In addition, HMG1 bound to Abeta (1-42) and stabilized the oligomerization. In AD brains, protein levels of HMG1 were significantly increased in both the cytosolic and particulate fractions, and HMG1 and Abeta were colocalized in senile plaques associated with Microglia. These results suggest that HMG1 may regulate the homeostasis of extracellular Abeta (1-42) and Abeta oligomerization

43. Thaker U, McDonagh AM, Iwatsubo T, Lendon CL, Pickering-Brown SM, Mann DM (2003) Tau load is associated with apolipoprotein E genotype and the amount of amyloid beta protein, Abeta40, in sporadic and familial Alzheimer's disease. Neuropathol.Appl.Neurobiol. 29:35-44
    Abstract: The total amount of hyperphosphorylated tau protein (p-tau load), present as neurofibrillary tangles (NFTs), neuropil threads or plaque neurites, was quantified in the frontal cortex of 109 cases of sporadic Alzheimer's disease (AD) and 35 cases of familial AD due to missense mutations in the presenilin-1, presenilin-2 and amyloid precursor protein genes. p-tau load was inversely correlated with age at onset of illness in both sporadic and familial AD but not with duration of disease. There was no difference in p-tau load between cases of familial AD and others with sporadic AD, matching the familial cases for apolipoprotein E (APO E) genotype. However, p-tau was greater in cases of familial and sporadic AD in the presence of APO E epsilon4 allele and increased with gene dose. Conversely, p-tau load tended to be lower when epsilon2 allele was present. In sporadic AD, tau load was highly significantly correlated with amyloid beta40 (Abeta40), but not Abeta42(43), load. These data indicate that the burden of pathological tau deposited in the brain in both familial and sporadic AD is favoured in the presence of APO E epsilon4 allele and also related to the amount of Abeta40, this also being higher when epsilon4 allele is present. Abeta40 plaques are rich in Microglial cells and it is possible that p-tau pathology in AD is triggered by reaction of Microglial cells to the presence of Abeta40 and not this peptide directly

44. Uryu S, Tokuhiro S, Oda T (2003) beta-Amyloid-specific upregulation of stearoyl coenzyme A desaturase-1 in macrophages. Biochem.Biophys.Res.Commun. 303:302-305
    Abstract: beta-Amyloid peptide (A beta), a major component of senile plaques, the formation of which is characteristic of Alzheimer's disease (AD), is believed to induce inflammation of the brain mediated by Microglia, leading to neuronal cell loss. In this study, we performed an oligonucleotide microarray analysis to investigate the molecular events underlying the A beta-induced activation of macrophages and its specific suppression by the A beta-specific-macrophage-activation inhibitor, RS-1178. Of the approximately 36,000 genes and expressed sequence tags analyzed, eight genes were specifically and significantly upregulated by a treatment with interferon gamma (IFN gamma) and A beta compared to a treatment with IFN gamma alone (p<0.002). We found that the gene for a well-characterized lipogenetic enzyme, stearoyl coenzyme A desaturase-1 (SCD-1), was specifically upregulated by A beta treatment and was suppressed to basal levels by RS-1178. Although the underlying mechanisms remain unknown, our results suggest the presence of a link between AD and SCD-1

45. Veerhuis R, Van Breemen MJ, Hoozemans JM, Morbin M, Ouladhadj J, Tagliavini F, Eikelenboom P (2003) Amyloid beta plaque-associated proteins C1q and SAP enhance the Abeta1-42 peptide-induced cytokine secretion by adult human Microglia in vitro. Acta Neuropathol.(Berl) 105:135-144
    Abstract: Pro-inflammatory cytokines released by activated Microglia could be a driving force in Alzheimer's disease (AD) pathology. We evaluated whether the presence of complement factor C1q and serum amyloid P component (SAP) in Abeta deposits is related to Microglial activation. Activated Microglia accumulate in SAP- and C1q-immunoreactive fibrillar amyloid beta (Abeta) plaques in AD temporal cortex. No clustered Microglia are seen in SAP- and C1q-positive circumscript, non-fibrillar, tau-negative Abeta plaques in AD caudate nucleus and non-demented control temporal cortex. In addition, no clustered Microglia were observed in C1q- and SAP-negative, irregular shaped, diffuse plaques in AD caudate nucleus and in non-demented control temporal cortex, which suggests that Microglia are attracted and activated in Abeta deposits of certain fibrillarity that, in addition, have fixed SAP and C1q. Therefore, the effects of Abeta(1-42), SAP and C1q on cytokine secretion by human postmortem Microglia in vitro were assessed. Abeta(1-42) alone had little to no effect. Abeta(1-42) peptides in combination with C1q or C1q and SAP increased Microglial interleukin (IL)-6 secretion four- and eightfold, respectively. Tumor necrosis factor (TNF)-alpha, as well as intracellular IL-1alpha and IL-1beta levels, also increased upon exposure of Microglia to Abeta(1-42)-SAP-C1q complexes. Combined with earlier findings, that amyloid and activated Microglia accumulate at a relatively early stage of cognitive decline in AD patients, this suggests that clustering of activated, cytokine-secreting Microglia in SAP- and C1q-containing Abeta deposits precedes neurodegenerative changes in AD, and thus may provide a "therapeutic window"

46. Vehmas AK, Kawas CH, Stewart WF, Troncoso JC (2003) Immune reactive cells in senile plaques and cognitive decline in Alzheimer's disease. Neurobiol.Aging 24:321-331
    Abstract: We examined the associations of postmortem neocortical immunoreactivities for Microglia, astrocytes, Abeta and Tau with cognitive changes in clinically characterized subjects with pathological diagnoses (CERAD classification) of definite AD (9), possible AD (15) and age-matched controls (11). By measuring the fractional area (FA) of immunoreactivity, we found that Abeta deposits appear early in the pathogenesis of Abeta, but cannot account for cognitive decline. We found a significant increases in FA for Microglia in possible AD cases (nondemented) compared to controls (P<0.05) and in FA for astrocytes in definite AD (demented) compared to possible AD (P<0.01). Tau immunoreactivity was observed only in the neuropil of definite AD cases (P<0.001). The significant increase in Microglia between controls and AD possible cases suggests that activation of Microglia occurs in the early pathogenesis of AD, whereas the significant association between astrocytic reaction and dementia, suggests that these cells play a role in the late stage of the disease, when dementia develops. Tau immunoreactivity appears as the strongest morphological correlate of dementia

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. Versijpt JJ, Dumont F, Van Laere KJ, Decoo D, Santens P, Audenaert K, Achten E, Slegers G, Dierckx RA, Korf J (2003) Assessment of neuroinflammation and Microglial activation in Alzheimer's disease with radiolabelled PK11195 and single photon emission computed tomography. A pilot study. Eur.Neurol. 50:39-47
    Abstract: OBJECTIVES: Inflammation contributes to degeneration in Alzheimer's disease (AD), not simply as a secondary phenomenon, but primarily as a significant source of pathology. [(123)I]iodo-PK11195 is a single photon emission computed tomography (SPECT) ligand for the peripheral benzodiazepine receptor, the latter being expressed on Microglia (brain resident macrophages) and upregulated under inflammatory circumstances. The objectives were to assess AD inflammation by detecting [(123)I]iodo-PK11195 uptake changes and investigate how uptake values relate with perfusion SPECT and neuropsychological findings. METHODS: Ten AD and 9 control subjects were included. [(123)I]iodo-PK11195 SPECT images were realigned into stereotactic space where binding indices, normalized on cerebellar uptake, were calculated. RESULTS: The mean [(123)I]iodo-PK11195 uptake was increased in AD patients compared with controls in nearly all neocortical regions; however, statistical significance was only reached in the frontal and right mesotemporal regions. Significant correlations were found between regional increased [(123)I]iodo-PK11195 uptake and cognitive deficits. CONCLUSIONS: [(123)I]iodo-PK11195 is a cellular disease activity marker and allows in vivo assessment of Microglial inflammation in AD

49. Watkins D (2003) Brain not inflamed? Alzheimer's may not be an inflammation after all. Sci.Am. 289:24-26

50. Wegiel J, Imaki H, Wang KC, Wegiel J, Wronska A, Osuchowski M, Rubenstein R (2003) Origin and turnover of Microglial cells in fibrillar plaques of APPsw transgenic mice. Acta Neuropathol.(Berl) 105:393-402
    Abstract: Activated Microglial cells are an integral component of fibrillar plaques in brains of subjects with Alzheimer's disease (AD) and in brains of transgenic mice overexpressing amyloidogenic fragments of human amyloid precursor protein (APP). The aim of this ultrastructural study of fibrillar plaques was to characterize the origin of Microglial cells involved in cored plaque formation. Computer-aided three-dimensional reconstruction of plaques and microvessels in APPsw transgenic mice shows perivascular development of cored plaques. Perivascular location of almost all examined plaques and the infiltration at the interface between vessels and plaques with cells of monocyte/Microglia lineage indicates that plaques are formed by inflammatory cells of blood origin. The increase in the number of Microglial cells from 1 or 2 in an early plaque to more than 100 in a several-month-old plaque does not result in plaque degradation, but is associated with amyloid core growth and progression of neuronal degeneration, and suggests that recruitment of inflammatory cells of blood origin sustains plaque growth. Infiltration of the plaque with cells of blood origin and degeneration of 10-46% of inflammatory cells in large plaques, which is especially frequent at the interface between capillary wall and plaque, suggest their accelerated turnover

51. White AR, Maher F, Brazier MW, Jobling MF, Thyer J, Stewart LR, Thompson A, Gibson R, Masters CL, Multhaup G, Beyreuther K, Barrow CJ, Collins SJ, Cappai R (2003) Diverse fibrillar peptides directly bind the Alzheimer's amyloid precursor protein and amyloid precursor-like protein 2 resulting in cellular accumulation. Brain Res. 966:231-244
    Abstract: The Alzheimer's disease Abeta peptide can increase the levels of cell-associated amyloid precursor protein (APP) in vitro. To determine the specificity of this response for Abeta and whether it is related to cytotoxicity, we tested a diverse range of fibrillar peptides including amyloid-beta (Abeta), the fibrillar prion peptides PrP106-126 and PrP178-193 and human islet-cell amylin. All these peptides increased the levels of APP and amyloid precursor-like protein 2 (APLP2) in primary cultures of astrocytes and neurons. Specificity was shown by a lack of change to amyloid precursor-like protein 1, tau-1 and cellular prion protein (PrP(c)) levels. APP and APLP2 levels were elevated only in cultures exposed to fibrillar peptides as assessed by electron microscopy and not in cultures treated with non-fibrillogenic peptide variants or aggregated lipoprotein. We found that PrP106-126 and the non-toxic but fibril-forming PrP178-193 increased APP levels in cultures derived from both wild-type and PrP(c)-deficient mice indicating that fibrillar peptides up-regulate APP through a non-cytotoxic mechanism and irrespective of parental protein expression. Fibrillar PrP106-126 and Abeta peptides bound recombinant APP and APLP2 suggesting the accumulation of these proteins was mediated by direct binding to the fibrillated peptide. This was supported by decreased APP accumulation following extensive washing of the cultures to remove fibrillar aggregates. Pre-incubation of fibrillar peptide with recombinant APP18-146, the putative fibril binding site, also abrogated the accumulation of APP. These findings show that diverse fibrillogenic peptides can induce accumulation of APP and APLP2 and this mechanism could contribute to pathogenesis in neurodegenerative disorders

52. Wilcock DM, DiCarlo G, Henderson D, Jackson J, Clarke K, Ugen KE, Gordon MN, Morgan D (2003) Intracranially administered anti-Abeta antibodies reduce beta-amyloid deposition by mechanisms both independent of and associated with Microglial activation. J.Neurosci. 23:3745-3751
    Abstract: Active immunization against the beta-amyloid peptide (Alphabeta) with vaccines or passive immunization with systemic monoclonal anti-Abeta antibodies reduces amyloid deposition and improves cognition in APP transgenic mice. In this report, intracranial administration of anti-Alphabeta antibodies into frontal cortex and hippocampus of Tg2576 transgenic APP mice is described. The antibody injection resulted initially in a broad distribution of staining for the antibody, which diminished over 7 d. Although no loss of immunostaining for deposited Abeta was apparent at 4 hr, a dramatic reduction in the Alphabeta load was discernible at 24 hr and was maintained at 3 and 7 d. A reduction in the thioflavine-S-positive compact plaque load was delayed until 3 d, at which time Microglial activation also became apparent. At 1 week after the injection, Microglial activation returned to control levels, whereas Alphabeta and thioflavine-S staining remained reduced. The results from this study suggest a two-phase mechanism of anti-Alphabeta antibody action. The first phase occurs between 4 and 24 hr, clears primarily diffuse Alphabeta deposits, and is not associated with observable Microglial activation. The second phase occurs between 1 and 3 d, is responsible for clearance of compact amyloid deposits, and is associated with Microglial activation. The results are discussed in the context of other studies identifying coincident Microglial activation and amyloid removal in APP transgenic animals

53. Yan Q, Zhang J, Liu H, Babu-Khan S, Vassar R, Biere AL, Citron M, Landreth G (2003) Anti-inflammatory drug therapy alters beta-amyloid processing and deposition in an animal model of Alzheimer's disease. J.Neurosci. 23:7504-7509
    Abstract: Alzheimer's disease (AD) is characterized by a Microglial-mediated inflammatory response elicited by extensive amyloid deposition in the brain. Nonsteroidal anti-inflammatory drug (NSAID) treatment reduces AD risk, slows disease progression, and reduces Microglial activation; however, the basis of these effects is unknown. We report that treatment of 11-month-old Tg2576 mice overexpressing human amyloid precursor protein (APP) with the NSAID ibuprofen for 16 weeks resulted in the dramatic and selective reduction of SDS-soluble beta-amyloid (Abeta)42, whereas it had smaller effects on SDS-soluble Abeta40 levels. Ibuprofen treatment resulted in 60% reduction of amyloid plaque load in the cortex of these animals. In vitro studies using APP-expressing 293 cells showed that ibuprofen directly affected APP processing, specifically reducing the production of Abeta42. Ibuprofen treatment resulted in a significant reduction in Microglial activation in the Tg2576 mice, as measured by CD45 and CD11b expression. NSAIDs activate the nuclear hormone receptor peroxisome proliferator-activated receptor gamma (PPARgamma); however, a potent agonist of this receptor, pioglitazone, only modestly reduced SDS-soluble Abeta levels and did not affect amyloid plaque burden or Microglia activation, indicating that PPARgamma activation is not involved in the Abeta lowering effect of NSAIDs. These data show that chronic NSAID treatment can reduce brain Abeta levels, amyloid plaque burden, and Microglial activation in an animal model of Alzheimer's disease

54. Aisen PS (2002) The potential of anti-inflammatory drugs for the treatment of Alzheimer's disease. Lancet Neurol. 1:279-284
    Abstract: Genetic evidence suggests that generation of amyloid beta peptide is the pivotal step in the pathophysiology of Alzheimer's disease (AD). The mechanism by which this peptide induces neurodegeneration may involve inflammatory processes. Pharmacological suppression of inflammation may therefore ameliorate the neuropathology. Basic research studies provide substantial evidence that inflammatory processes present in the brains of patients with AD are destructive, and that anti-inflammatory drugs can provide protection. Furthermore, epidemiological studies suggest that anti-inflammatory drugs reduce the risk of AD. However, there is not yet any strong evidence from completed randomised controlled trials that anti-inflammatory treatment is beneficial. Large trials of glucocorticoid therapy, hydroxychloroquine, and non-steroidal anti-inflammatory drugs (NSAIDs) in the treatment of AD have so far been disappointing. Several studies, including a large primary prevention trial with NSAIDs, are still in progress. Major issues of selection of patients, drug regimen, and duration of treatment remain unresolved

55. Ali-Khan Z (2002) Searching for an in vivo site for nascent amyloid fibril formation. J.Alzheimers.Dis. 4:105-114

56. Apelt J, Lessig J, Schliebs R (2002) Beta-amyloid-associated expression of intercellular adhesion molecule-1 in brain cortical tissue of transgenic Tg2576 mice. Neurosci.Lett. 329:111-115
    Abstract: To study the relationship of beta-amyloid-mediated micro- and astrogliosis and inflammation-induced proteins including intercellular adhesion molecule (ICAM-1), brain tissue from transgenic Tg2576 mice expressing the Swedish mutation of the human amyloid precursor protein were examined for ICAM-1 expression. Immunocytochemistry demonstrated a diffuse immunostaining of ICAM-1 in the corona around fibrillary beta-amyloid plaques and an upregulation of ICAM-1 in activated Microglial cells located in close proximity to the plaques, an ICAM-1 distribution pattern that partly mimics the situation in the brain of Alzheimer patients. The developmental time course revealed that the rate of cortical ICAM-1 induction was somewhat behind that of the progression of beta-amyloid plaque deposition. The Microglial expression of ICAM-1 is a further indicator of the presence of inflammatory reactions in aged transgenic Tg2576 mouse brain, and may be a result of plaque-mediated astrocytic interleukin-1beta upregulation

57. Arelin K, Kinoshita A, Whelan CM, Irizarry MC, Rebeck GW, Strickland DK, Hyman BT (2002) LRP and senile plaques in Alzheimer's disease: colocalization with apolipoprotein E and with activated astrocytes. Brain Res.Mol.Brain Res. 104:38-46
    Abstract: The low density lipoprotein receptor-related protein (LRP) is a multifunctional receptor which is present on senile plaques in Alzheimer's disease (AD). It is suggested to play an important role in the balance between amyloid beta (Abeta) synthesis and clearance mechanisms. One of its ligands, apolipoprotein E (apoE), is also present on senile plaques and has been implicated as a risk factor for AD, potentially affecting the deposition, fibrillogenesis and clearance of Abeta. Using immunohistochemistry we show that LRP was present only on cored, apoE-containing senile plaques, in both PDAPP transgenic mice and human AD brains. We detected strong LRP staining in neurons and in reactive astrocytes, and immunostaining of membrane-bound LRP showed colocalization with fine astrocytic processes surrounding senile plaques. LRP was not present in plaques in young transgenic mice or in plaques of APOE-knockout mice. As LRP ligands associated with Abeta deposits in AD brain may play an important role in inducing levels of LRP in both neurons and astrocytes, our findings support the idea that apoE might be involved in upregulation of LRP (present in fine astrocytic processes) and act as a local scaffolding protein for LRP and Abeta. The upregulation of LRP would allow increased clearance of LRP ligands as well as clearance of Abeta/ApoE complexes

58. Bacskai BJ, Kajdasz ST, McLellan ME, Games D, Seubert P, Schenk D, Hyman BT (2002) Non-Fc-mediated mechanisms are involved in clearance of amyloid-beta in vivo by immunotherapy. J.Neurosci. 22:7873-7878
    Abstract: Transgenic (Tg) mouse models overexpressing amyloid precursor protein (APP) develop senile plaques similar to those found in Alzheimer's disease in an age-dependent manner. Recent reports demonstrated that immunotherapy is effective at preventing or removing amyloid-beta deposits in the mouse models. To characterize the mechanisms involved in clearance, we used antibodies of either IgG1 (10d5) or IgG2b (3d6) applied directly to the brains of 18-month-old Tg2576 or 20-month-old PDAPP mice. Both 10d5 and 3d6 led to clearance of 50% of diffuse amyloid deposits in both animal models within 3 d. Fc receptor-mediated clearance has been shown to be important in an ex vivo assay showing antibody-mediated clearance of plaques by Microglia. We now show, using in vivo multiphoton microscopy, that FITC-labeled F(ab')2 fragments of 3d6 (which lack the Fc region of the antibody) also led to clearance of 45% of the deposits within 3 d, similar to the results obtained with full-length 3d6 antibody. This result suggests that direct disruption of plaques, in addition to Fc-dependent phagocytosis, is involved in the antibody-mediated clearance of amyloid-beta deposits in vivo. Dense-core deposits that were not cleared were reduced in size by approximately 30% with full-length antibodies and F(ab')2 fragments 3 d after a topical treatment. Together, these results indicate that clearance of amyloid deposits in vivo may involve, in addition to Fc-dependent clearance, a non-Fc-mediated disruption of plaque structure

59. Bamberger ME, Landreth GE (2002) Inflammation, apoptosis, and Alzheimer's disease. Neuroscientist. 8:276-283
    Abstract: The pathophysiology of Alzheimer's disease (AD) involves the deposition of amyloid in the brain and the extensive loss of neurons. The mechanisms subserving neuronal death in the disease remain unclear, although it has been postulated that this is due to apoptosis. There is compelling evidence that inflammatory processes play a role in disease progression and pathology. Amyloid plaque deposition is accompanied by the association of Microglia with the senile plaque, and this interaction stimulates these cells to undergo phenotypic activation and the subsequent elaboration of proinflammatory and neurotoxic products. This review focuses on the mechanisms by which neurons are lost in AD and the role Microglial proinflammatory products play in neuronal death

60. Bi X, Gall CM, Zhou J, Lynch G (2002) Uptake and pathogenic effects of amyloid beta peptide 1-42 are enhanced by integrin antagonists and blocked by NMDA receptor antagonists. Neuroscience 112:827-840
    Abstract: Many synapses contain two types of receptors - integrins and N-methyl-D-aspartate (NMDA) receptors - that have been implicated in peptide internalization. The present studies tested if either class is involved in the uptake of the 42-residue form of amyloid beta peptide (Abeta1-42), an event hypothesized to be of importance in the development of Alzheimer's disease. Cultured hippocampal slices were exposed to Abeta1-42 for 6 days in the presence or absence of soluble Gly-Arg-Gly-Asp-Ser-Pro, a peptide antagonist of Arg-Gly-Asp (RGD)-binding integrins, or the disintegrin echistatin. Abeta uptake, as assessed with immunocytochemistry, occurred in 42% of the slices incubated with Abeta peptide alone but in more than 80% of the slices co-treated with integrin antagonists. Uptake was also found in a broader range of hippocampal subfields in RGD-treated slices. Increased sequestration was accompanied by two characteristics of early stage Alzheimer's disease: elevated concentrations of cathepsin D immunoreactivity and activation of Microglia. The selective NMDA receptor antagonist D-(-)-2-amino-5-phosphonovalerate completely blocked internalization of Abeta, up-regulation of cathepsin D, and activation of Microglia. Our results identify two classes of receptors that cooperatively regulate the internalization of Abeta1-42 and support the hypothesis that characteristic pathologies of Alzheimer's disease occur once critical intraneuronal Abeta concentrations are reached

61. Bondolfi L, Calhoun M, Ermini F, Kuhn HG, Wiederhold KH, Walker L, Staufenbiel M, Jucker M (2002) Amyloid-associated neuron loss and gliogenesis in the neocortex of amyloid precursor protein transgenic mice. J.Neurosci. 22:515-522
    Abstract: APP23 transgenic mice express mutant human amyloid precursor protein and develop amyloid plaques predominantly in neocortex and hippocampus progressively with age, similar to Alzheimer's disease. We have previously reported neuron loss in the hippocampal CA1 region of 14- to 18-month-old APP23 mice. In contrast, no neuron loss was found in neocortex. In the present study we have reinvestigated neocortical neuron numbers in adult and aged APP23 mice. Surprisingly, results revealed that 8-month-old APP23 mice have 13 and 14% more neocortical neurons compared with 8-month-old wild-type and 27-month-old APP23 mice, respectively. In 27-month-old APP23 mice we found an inverse correlation between amyloid load and neuron number. These results suggest that APP23 mice have more neurons until they develop amyloid plaques but then lose neurons in the process of cerebral amyloidogenesis. Supporting this notion, we found more neurons with a necrotic-apoptotic phenotype in the neocortex of 24-month-old APP23 mice compared with age-matched wild-type mice. Stimulated by recent reports that demonstrated neurogenesis after targeted neuron death in the mouse neocortex, we have also examined neurogenesis in APP23 mice. Strikingly, we found a fourfold to sixfold increase in newly produced cells in 24-month-old APP23 mice compared with both age-matched wild-type mice and young APP23 transgenic mice. However, subsequent cellular phenotyping revealed that none of the newly generated cells in neocortex had a neuronal phenotype. The majority were Microglial and to a lesser extent astroglial cells. We conclude that cerebral amyloidosis in APP23 mice causes a modest neuron loss in neocortex and induces marked gliogenesis

62. Brown CM, Wright E, Colton CA, Sullivan PM, Laskowitz DT, Vitek MP (2002) Apolipoprotein E isoform mediated regulation of nitric oxide release. Free Radic.Biol.Med. 32:1071-1075
    Abstract: Progressive dysfunction and death of neurons in Alzheimer's dementia is enhanced in patients carrying one or more APOE4 alleles who also display increased presence of oxidative stress markers. Modulation of oxidative stress is a nontraditional and physiologically relevant immunomodulatory function of apolipoprotein E (apoE). Stimulated peritoneal macrophages from APOE-transgenic replacement (APOE-TR) mice expressing only human apoE3 or human apoE4 protein isoforms were utilized as mouse models to investigate the role of apoE protein isoforms and gender in the regulation of oxidative stress. Macrophages from male APOE4/4-TR mice produced significantly higher levels of nitric oxide than from male APOE3/3-TR mice, while macrophages from female APOE3/3-TR and female APOE4/4-TR mice produced the similar levels of nitric oxide. Primary cultures of Microglial cells of APOE4 transgenic mice also produced significantly more nitric oxide than Microglia from APOE3 transgenic mice. These data suggest a potentially novel mechanism for gender-dependent and apoE isoform-dependent immune responses that parallel the genetic susceptibility of APOE4 carriers for the development of Alzheimer's disease

63. Butterfield DA, Griffin S, Munch G, Pasinetti GM (2002) Amyloid beta-peptide and amyloid pathology are central to the oxidative stress and inflammatory cascades under which Alzheimer's disease brain exists. J.Alzheimers.Dis. 4:193-201
    Abstract: Alzheimer's disease (AD) brain is characterized by excess deposition of amyloid beta-peptide (Abeta), particularly the 42-amino acid peptide [Abeta(1-42)] and by extensive oxidative stress. Several sources of the oxidative stress and inflammatory cascades are likely, including that induced by advanced glycation end products, Microglial activation, and by Abeta(1-42) and its sequelae. This review briefly examines each of these sources of oxidative stress and inflammation in AD brain and discusses their potential roles in the clinical progression of AD dementia

64. Calingasan NY, Erdely HA, Anthony AC (2002) Identification of CD40 ligand in Alzheimer's disease and in animal models of Alzheimer's disease and brain injury. Neurobiol.Aging 23:31-39
    Abstract: Chronic neuroinflammatory processes including glial activation may play a role in the pathogenesis of Alzheimer's disease (AD). The immune and inflammatory mediator CD40 ligand (CD40L) can augment the activation of cultured Microglia by amyloid beta-protein (Abeta) and promote neuron death. We investigated whether CD40L is increased in AD and in animal models of AD and neuroinflammation. In the frontal cortex of elderly, non-AD controls, CD40L immunoreactivity was found in the glial limiting membrane, astrocytes, and vascular profiles in gray and white matter. In AD, intense CD40L immunoreactivity occurred in hypertrophied astrocytes throughout the frontal cortex. The majority of CD40L-immunoreactive astrocytes in the gray matter occurred within, or at the periphery of, Abeta(1-42)-immunoreactive plaques. A semiquantitative analysis revealed a three-fold elevation in the number of CD40L-immunoreactive astrocytes in AD compared to controls. The cortex and hippocampus from 6 and 12 month-old amyloid precursor protein/presenilin 1 transgenic mice exhibited numerous neuritic plaques and CD40L-positive astrocytes, which were not detected in non-transgenic controls. In adult rats, little or no CD40L staining occurred in astrocytes of the intact brain, whereas intrastriatal excitotoxic or stab wound lesions produced a strong CD40L immunoreactivity that was more segregated than glial fibrillary acidic protein. These findings indicate that astrocytes are the predominant source of CD40L in brain, and are consistent with the proposed role of CD40L-mediated neurotoxic inflammation in AD

65. Casal C, Serratosa J, Tusell JM (2002) Relationship between beta-AP peptide aggregation and Microglial activation. Brain Res. 928:76-84
    Abstract: We compared the relationship between the state of aggregation of two peptides (beta-AP 25-35 and beta-AP 1-42) and Microglial activation. After 7 days at 37 degrees C beta-AP 25-35 was in an amorphous state and did not activate Microglial cells. In the same conditions, aggregated beta-AP 1-42 activated these cells and caused changes in Microglial ramification, increasing the proliferation index and inducing tumor necrosis factor alpha (TNF alpha) release. Neither peptide induced a release of nitric oxide (NO). As the toxicity of beta-AP peptides in cell culture is associated with the formation of amyloid fibrils, we also examined the toxicity of both peptides in Microglial cell cultures and in PC 12 cell cultures. The results suggest that the two beta-AP fragments studied have similar neurotoxic effects but different pro-inflammatory activities

66. Colton CA, Brown CM, Cook D, Needham LK, Xu Q, Czapiga M, Saunders AM, Schmechel DE, Rasheed K, Vitek MP (2002) APOE and the regulation of Microglial nitric oxide production: a link between genetic risk and oxidative stress. Neurobiol.Aging 23:777-785
    Abstract: The mechanism linking the APOE4 gene with increased susceptibility for Alzheimer's disease (AD) and poorer outcomes following closed head injury and stroke is unknown. One potential link is activation of the innate immune system in the CNS. Our previously published data demonstrated that apolipoprotein E regulates production of nitric oxide, a critical cytoactive factor released by immune active macrophages. To determine if immune regulation is different in the presence of apolipoprotein E4 compared to apolipoprotein E3, we have measured NO production by peritoneal and CNS macrophages (Microglia) cultured from transgenic mice that only express the human apoE4 or apoE3 protein isoform. Significantly more NO was produced in APOE4 mice compared to APOE3 transgenic mice that only express human apoE3 protein. Similarly, monocyte derived macrophages from humans carrying APOE4 gene alleles also produce significantly greater NO than those individuals with APOE3. The mechanism for this isoform-specific difference in NO production is not known and multiple sites in the NO production pathway may be affected. Expression of inducible nitric oxide synthase (iNOS) mRNA and protein are not significantly different between the APOE3 and APOE4 mice, suggesting that induction of iNOS is not a primary cause of the increased NO production in APOE4 animals. One alternative regulatory mechanism that demonstrates isoform specificity is arginine transport, which is greater in Microglia from APOE4 transgenic mice compared to Microglia from APOE3 mice. Increased transport is consistent with an increased production of NO and may reflect a direct or indirect effect of the APOE genotype on Microglial arginine uptake and Microglial activation in general. Overall, greater NO production in APOE4 carriers where characteristically high levels of oxidative/nitrosative stress are found in diseases such as AD provides a mechanism that potentially explains the genetic association between APOE4 and human diseases

67. Colton CA, Brown CM, Czapiga M, Vitek MP (2002) Apolipoprotein-E allele-specific regulation of nitric oxide production. Ann.N.Y.Acad.Sci. 962:212-225
    Abstract: Cognitive decline and dementia are key features of Alzheimer's disease (AD) that result from failure of neuronal function. Affected neurons demonstrate indices of nitrosative stress resulting from changes in nitric oxide (NO) mediated redox balance. Neurofibrillary tangles, a characteristic neuropathologic feature of AD, and dysfunctional neurons frequently display 3-nitrotyrosine or other markers of nitrosative stress and immunoreactive nitric oxide synthase (NOS), suggesting that NOS-containing neurons are affected in AD. Our previous studies showed that apolipoprotein E treatment of macrophages increased NO production. Using transgenic mouse models expressing human apoE2, apoE3, or apoE4 protein isoforms and no mouse apoE, we now report an isoform specific difference in Microglial NO production. Mice expressing the apoE4 protein isoform have a greater NO production than mice expressing the apoE3 protein isoform. The supply of arginine, the sole substrate for NOS, is dependent on cationic amino acid transporters (CATs) that also demonstrate a similar pattern of apoE isoform dependency. Although arginine transport is greater in APOE4 Microglia, this effect is not limited to tissue macrophages. Cortical neurons in primary culture from APOE4 transgenic mice exhibit a similar increase in arginine uptake over neurons cultured from APOE3 mice. The inappropriate levels of arginine transport and of NO in the presence of the APOE4 compared to the APOE3 gene and its products are likely to have significant impact in the CNS

68. Combarros O, Infante J, Llorca J, Pena N, Fernandez-Viadero C, Berciano J (2002) The myeloperoxidase gene in Alzheimer's disease: a case-control study and meta-analysis. Neurosci.Lett. 326:33-36
    Abstract: Myeloperoxidase (MPO) presence has been demonstrated in Microglia associated with senile plaques, and contributes to Alzheimer's disease (AD) pathology through oxidation-induced damage. Recently, a functional biallelic (G/A) polymorphism in the promotor region (-463) of the MPO gene has been associated with susceptibility to AD, but the reports of this association have been inconsistent. A case-control study utilizing a clinically well-defined group of 315 sporadic AD patients and 327 control subjects was performed to test this association. The current study does not demonstrate any significant difference in MPO genotype or allele frequencies between AD patients and controls. A meta-analysis of all studies available gave a non-significant (P=0.83) odds ratio of 1.02 for the MPO GG genotype. Our study in the Spanish population as well as the meta-analysis argue against the hypothesis that the MPO gene is causally related to AD

69. Coraci IS, Husemann J, Berman JW, Hulette C, Dufour JH, Campanella GK, Luster AD, Silverstein SC, El Khoury JB (2002) CD36, a class B scavenger receptor, is expressed on Microglia in Alzheimer's disease brains and can mediate production of reactive oxygen species in response to beta-amyloid fibrils. Am.J.Pathol. 160:101-112
    Abstract: A pathological hallmark of Alzheimer's disease is the senile plaque, composed of beta-amyloid fibrils, Microglia, astrocytes, and dystrophic neurites. We reported previously that class A scavenger receptors mediate adhesion of Microglia and macrophages to beta-amyloid fibrils and oxidized low-density lipoprotein (oxLDL)-coated surfaces. We also showed that CD36, a class B scavenger receptor and an oxLDL receptor, promotes H(2)O(2) secretion by macrophages adherent to oxLDL-coated surfaces. Whether CD36 is expressed on Microglia, and whether it plays a role in secretion of H(2)O(2) by Microglia interacting with fibrillar beta-amyloid is not known. Using fluorescence-activated cell sorting analysis and immunohistochemistry, we found that CD36 is expressed on human fetal Microglia, and N9-immortalized mouse Microglia. We also found that CD36 is expressed on Microglia and on vascular endothelial cells in the brains of Alzheimer's disease patients. Bowes human melanoma cells, which normally do not express CD36, gained the ability to specifically bind to surfaces coated with fibrillar beta-amyloid when transfected with a cDNA encoding human CD36, suggesting that CD36 is a receptor for fibrillar beta-amyloid. Furthermore, two different monoclonal antibodies to CD36 inhibited H(2)O(2) production by N9 Microglia and human macrophages adherent to fibrillar beta-amyloid by approximately 50%. Our data identify a role for CD36 in fibrillar beta-amyloid-induced H(2)O(2) production by Microglia, and imply that CD36 can mediate binding to fibrillar beta-amyloid. We propose that similar to their role in the interaction of macrophages with oxLDL, class A scavenger receptors and CD36 play complimentary roles in the interactions of Microglia with fibrillar beta-amyloid

70. Cui Y, Le Y, Yazawa H, Gong W, Wang JM (2002) Potential role of the formyl peptide receptor-like 1 (FPRL1) in inflammatory aspects of Alzheimer's disease. J.Leukoc.Biol. 72:628-635
    Abstract: Alzheimer's disease (AD) is a progressive, neurodegenerative disease characterized by the presence of multiple senile plaques in the brain tissue, which are also associated with considerable inflammatory infiltrates. Although the precise mechanisms of the pathogenesis of AD remain to be determined, the overproduction and precipitation of a 42 amino acid form of beta amyloid (Abeta(42)) in plaques have implicated Abeta in neurodegeneration and proinflammatory responses seen in the AD brain. Our recent studies revealed that the activation of formyl peptide receptor-like 1 (FPRL1), a seven-transmembrane, G-protein-coupled receptor, by Abeta(42) may be responsible for accumulation and activation of mononuclear phagocytes (monocytes and Microglia). We further found that upon binding FPRL1, Abeta(42) was rapidly internalized into the cytoplasmic compartment in the form of Abeta(42)/FPRL1 complexes. Persistent exposure of FPRL1-expressing cells to Abeta(42) resulted in intracellular retention of Abeta(42)/FPRL1 complexes and the formation of Congo-red-positive fibrils in mononuclear phagocytes. Our observations suggest that FPRL1 may not only mediate the proinflammatory activity of Abeta(42) but also actively participate in Abeta(42) uptake and the resultant fibrillar formation. Therefore, FPRL1 may constitute an additional molecular target for the development of therapeutic agents for AD

71. Czlonkowska A, Kurkowska-Jastrzebska I (2002) [The role of inflammatory reaction in Alzheimer's disease and neurodegenerative processes]. Neurol.Neurochir.Pol. 36:15-23
    Abstract: Recent studies state that specific inflammatory mechanisms contribute to neurodegeneration. The theory is based on laboratory evidence of local upregulation of inflammatory cytokines (ex. IL-1, IL-6), acute phase proteins (ex. alpha 1-antitrypsin), activation of the complement cascade and accumulation of Microglia in damaged regions in AD. In addition epidemiologic studies suggest that anti-inflammatory treatment provides some protection from AD. The first trials with prednisone fail to show any positive influence in AD patients. The alternative therapies are now considered with nonsteroid anti-inflammatory drugs, colchicine, cyclophosphamide. The anti-inflammatory treatment gives hope for slowing progression of the disease and decline of AD incidence

72. DeGiorgio LA, Manuelidis L, Bernstein JJ (2002) Transient appearance of amyloid precursor protein plaques in the brain of thymectomized rats after human leptomeningeal cell grafts. Neurosci.Lett. 322:62-66
    Abstract: Cells cultured from Alzheimer disease leptomeninges or skin were grafted into the cortex of adult thymectomized rats. At 3 days post-implant, plaque-like aggregates were found in the cortex, corpus callosum, septum and caudate nucleus. These structures were immunopositive for human amyloid precursor protein (APP), human amyloid beta peptide (Abeta), cathepsin D, apolipoprotein E and ubiquitin. Aberrant tau+ neurites, reactive astrocytes and Microglia were associated with many aggregates. Although birefringent amyloid occupied the central area of most aggregates, these structures had disappeared by l month post-implant. Abeta and APP produced by grafted non-neural human cells can penetrate rat brain and form plaque-like structures, which can be effectively cleared by the rat

73. Eikelenboom P, Hoogendijk WJ, Jonker C, van Tilburg W (2002) Immunological mechanisms and the spectrum of psychiatric syndromes in Alzheimer's disease. J.Psychiatr.Res. 36:269-280
    Abstract: Pathological, genetic and epidemiological studies support the opinion that inflammatory mechanisms are involved in the pathogenesis of Alzheimer's disease (AD). Recent pathological and neuroradiological (PET) data show that activation of Microglia is an early pathogenic event that precedes the process of severe neuropil destruction in AD brains. In this paper we review the evidence that inflammatory mediators can play a pathogenic role in some behavioural disorders frequently encountered during the clinical course in AD patients. Motivational disturbances are the most striking of the depressive symptoms in AD and can be present in a preclinical stage of the disease. Experimental animal studies and clinical trials in humans have shown that cytokines can induce similar symptoms which were described as 'sickness behaviour' or 'depressive-like' state. Delirious states are frequently observed in more advanced stages of dementia. Delirium is generally considered the result of an imbalance in neurotransmitter systems with severe deficits of the cholinergic systems. Animal studies show that pro-inflammatory cytokines, such as interleukin-1, induce a reduced activity of the cholinergic system. In AD, the release of cytokines would exacerbate any already existing disturbances in the cholinergic neurotransmission. This could explain the susceptibility of demented patients to delirium provoked by a wide variety of trivial incidents that are accompanied by an acute phase response. The data reviewed in this paper suggest that it could be worthwhile employing a neuroimmunological approach to study at molecular level the pathogenesis of a broad spectrum of behavioural disturbances common in the clinical course of AD patients

74. Eikelenboom P, Bate C, Van Gool WA, Hoozemans JJ, Rozemuller JM, Veerhuis R, Williams A (2002) Neuroinflammation in Alzheimer's disease and prion disease. Glia 40:232-239
    Abstract: Alzheimer's disease (AD) and prion disease are characterized neuropathologically by extracellular deposits of Abeta and PrP amyloid fibrils, respectively. In both disorders, these cerebral amyloid deposits are co-localized with a broad variety of inflammation-related proteins (complement factors, acute-phase protein, pro-inflammatory cytokines) and clusters of activated Microglia. The present data suggest that the cerebral Abeta and PrP deposits are closely associated with a locally induced, non-immune-mediated chronic inflammatory response. Epidemiological studies indicate that polymorphisms of certain cytokines and acute-phase proteins, which are associated with Abeta plaques, are genetic risk factors for AD. Transgenic mice studies have established the role of amyloid associated acute-phase proteins in Alzheimer amyloid formation. In contrast to AD, there is a lack of evidence that cytokines and acute-phase proteins can influence disease progression in prion disease. Clinicopathological and neuroradiological studies have shown that activation of Microglia is a relatively early pathogenetic event that precedes the process of neuropil destruction in AD patients. It has also been found that the onset of Microglial activation coincided in mouse models of prion disease with the earliest changes in neuronal morphology, many weeks before neuronal loss and subsequent clinical signs of disease. In the present work, we review the similarities and differences between the involvement of inflammatory mechanisms in AD and prion disease. We also discuss the concept that the demonstration of a chronic inflammatory-like process relatively early in the pathological cascade of both diseases suggests potential therapeutic strategies to prevent or to retard these chronic neurodegenerative disorders

75. Fiala M, Liu QN, Sayre J, Pop V, Brahmandam V, Graves MC, Vinters HV (2002) Cyclooxygenase-2-positive macrophages infiltrate the Alzheimer's disease brain and damage the blood-brain barrier. Eur.J.Clin.Invest 32:360-371
    Abstract: BACKGROUND: Monocyte/macrophages are known to infiltrate the brain of patients with HIV-1 encephalitis (HIVE). In Alzheimer's disease brain, the origin of activated Microglia has not been determined. MATERIALS AND METHODS: We employed the antigen retrieval technique, immunocytochemistry, immunofluorescense, and confocal microscopy to identify macrophages and Microglia in relation to amyloid-beta plaques and the blood-brain barrier in autopsy brain tissues from patients with Alzheimer's disease (AD) and HIVE. RESULTS: In both conditions, cyclooxygenase-2 positive macrophages and, to a lesser degree, T and B cells infiltrate brain perivascular spaces and neuropil. The macrophages are distinguishable from ramified Microglia, and decorate the vessels at the sites of apparent of endothelial tight junction protein ZO-1 disruption. The macrophages also infiltrate amyloid-beta plaques, display intracellular amyloid-beta and are surrounded by amyloid-beta-free lacunae. Furthermore, the macrophages partially encircle the walls of amyloid-beta-containing vessels in amyloid angiopathy, and exhibit intracellular amyloid-beta but not paracellular lacunae. Significantly larger zones of fibrinogen leakage surround the microvessels in HIVE brain tissues compared with AD tissues (P = 0.034), and AD tissues have significantly greater leakage than control tissues (P = 0.0339). The AD group differs from a normal control age-matched group with respect to both the area occupied by CD68 (P = 0.03) and cyclooxygenase-2 immunoreactive cells (P = 0.004). CONCLUSION: In both HIVE and AD, blood-borne activated monocyte/macrophages and lymphocytes appear to migrate through a disrupted blood-brain barrier. The lacunae around macrophages in amyloid-beta plaques but not in vessel walls are consistent with the ability of macrophages to phagocytize and clear amyloid-beta deposits in vitro

76. Giovannini MG, Scali C, Prosperi C, Bellucci A, Vannucchi MG, Rosi S, Pepeu G, Casamenti F (2002) Beta-amyloid-induced inflammation and cholinergic hypofunction in the rat brain in vivo: involvement of the p38MAPK pathway. Neurobiol.Dis. 11:257-274
    Abstract: Injection into the nucleus basalis of the rat of preaggregated Abeta(1-42) produced a congophylic deposit and Microglial and astrocyte activation and infiltration and caused a strong inflammatory reaction characterized by IL-1beta production, increased inducible cyclooxygenase (COX-2), and inducible nitric oxide synthase (iNOS) expression. Many phospho-p38MAPK-positive cells were observed around the deposit at 7 days after Abeta injection. Phospho-p38MAPK colocalized with activated Microglial cells, but not astrocytes. The inflammatory reaction was accompanied by cholinergic hypofunction. We investigated the protective effect of the selective COX-2 inhibitor rofecoxib in attenuating the inflammatory response and neurodegeneration evoked by Abeta(1-42). Rofecoxib (3 mg/kg/day, 7 days) reduced Microglia and astrocyte activation, iNOS induction, and p38MAPK activation to control levels. Cholinergic hypofunction was also significantly attenuated by treatment with rofecoxib. We show here for the first time in vivo the pivotal role played by the p38MAPK Microglial signal transduction pathway in the inflammatory response to the Abeta(1-42) deposit

77. Giri R, Selvaraj S, Miller CA, Hofman F, Yan SD, Stern D, Zlokovic BV, Kalra VK (2002) Effect of endothelial cell polarity on beta-amyloid-induced migration of monocytes across normal and AD endothelium. Am.J.Physiol Cell Physiol 283:C895-C904
    Abstract: During normal aging and amyloid beta-peptide (Abeta) disorders such as Alzheimer's disease (AD), one finds increased deposition of Abeta and activated monocytes/Microglial cells in the brain. Our previous studies show that Abeta interaction with a monolayer of normal human brain microvascular endothelial cells results in increased adherence and transmigration of monocytes. Relatively little is known of the role of Abeta accumulated in the AD brain in mediating trafficking of peripheral blood monocytes (PBM) across the blood-brain barrier (BBB) and concomitant accumulation of monocytes/Microglia in the AD brain. In this study, we showed that interaction of Abeta(1--40) with apical surface of monolayer of brain endothelial cells (BEC), derived either from normal or AD individuals, resulted in increased transendothelial migration of monocytic cells (HL-60 and THP-1) and PBM. However, transmigration of monocytes across the BEC monolayer cultivated in a Transwell chamber was increased 2.5-fold when Abeta was added to the basolateral side of AD compared with normal individual BEC. The Abeta-induced transmigration of monocytes was inhibited in both normal and AD-BEC by antibodies to the putative Abeta receptor, receptor for advanced glycation end products (RAGE), and to the endothelial cell junction molecule, platelet-endothelial cell adhesion molecule-1 (PECAM-1). We conclude that interaction of Abeta with the basolateral surface of AD-BEC induces cellular signaling, promoting transmigration of monocytes from the apical to basolateral direction. We suggest that Abeta in the AD brain parenchyma or cerebrovasculature initiates cellular signaling that induces PBM to transmigrate across the BBB and accumulate in the brain

78. Gordon MN, Holcomb LA, Jantzen PT, DiCarlo G, Wilcock D, Boyett KW, Connor K, Melachrino J, O'Callaghan JP, Morgan D (2002) Time course of the development of Alzheimer-like pathology in the doubly transgenic PS1+APP mouse. Exp.Neurol. 173:183-195
    Abstract: Doubly transgenic mice expressing both a mutated amyloid precursor protein and a mutated presenilin-1 protein accumulate A(beta) deposits as they age. The early A(beta) deposits were found to be primarily composed of fibrillar A(beta) and resembled compact amyloid plaques. As the mice aged, nonfibrillar A(beta) deposits increased in number and spread to regions not typically associated with amyloid plaques in Alzheimer's disease. The fibrillar, amyloid-containing deposits remained restricted to cortical and hippocampal structures and did not increase substantially beyond the 12-month time point. Even at early time points, the fibrillar deposits were associated with dystrophic neurites and activated astrocytes expressing elevated levels of glial fibrillary acidic protein. Microglia similarly demonstrated increased staining for complement receptor-3 in the vicinity of A(beta) deposits at early time points. However, when MHC-II staining was used to assess the degree of Microglial activation, full activation was not detected until mice were 12 months or older. Overall, the regional pattern of A(beta) staining resembles that found in Alzheimer disease; however, a progression from diffuse A(beta) to more compact amyloid deposits is not observed in the mouse model. It is noted that the activation of Microglia at 12 months is coincident with the apparent stabilization of fibrillar A(beta) deposits, raising the possibility that activated Microglia might clear fibrillar A(beta) deposits at a rate similar to their rate of formation, thereby establishing a relatively steady-state level of amyloid-containing deposits

79. Griffin WS, Mrak RE (2002) Interleukin-1 in the genesis and progression of and risk for development of neuronal degeneration in Alzheimer's disease. J.Leukoc.Biol. 72:233-238
    Abstract: Interleukin-1 (IL-1), a key molecule in systemic immune responses in health and disease, has analogous roles in the brain where it may contribute to neuronal degeneration. Numerous findings suggest that this is the case. For example, IL-1 overexpression in the brain of Alzheimer patients relates directly to the development and progression of the cardinal neuropathological changes of Alzheimer's disease, i.e., the genesis and accumulation of beta-amyloid (Abeta) plaques and the formation and accumulation of neurofibrillary tangles in neurons, both of which contribute to neuronal dysfunction and demise. Several genetic studies show that inheritance of a specific IL-1A gene polymorphism increases risk for development of Alzheimer's disease by as much as sixfold. Moreover, this increased risk is associated with earlier age of onset of the disease. Homozygosity for this polymorphism in combination with another in the IL-1B gene further increases risk

80. Guillemin GJ, Brew BJ (2002) Implications of the kynurenine pathway and quinolinic acid in Alzheimer's disease. Redox.Rep. 7:199-206
    Abstract: The kynurenine pathway (KP) is a major route of L-tryptophan catabolism leading to production of a number of biologically active molecules. Among them, the neurotoxin quinolinic acid (QUIN), is considered to be involved in the pathogenesis of a number of inflammatory neurological diseases. Alzheimer's disease is the major dementing disorder of the elderly that affects over 20 million peoples world-wide. Most of the approaches to explain the pathogenesis of Alzheimer's disease focus on the accumulation of amyloid beta peptide (A beta), in the form of insoluble deposits leading to formation of senile plaques, and on the formation of neurofibrillary tangles composed of hyperphosphorylated Tau protein. Accumulation of A beta is believed to be an early and critical step in the neuropathogenesis of Alzheimer's disease. There is now evidence for the KP being associated with Alzheimer's disease. Disturbances of the KP have already been described in Alzheimer's disease. Recently, we demonstrated that A beta 1-42, a cleavage product of amyloid precursor protein, induces production of QUIN, in neurotoxic concentrations, by macrophages and, more importantly, Microglia. Senile plaques in Alzheimer's disease are associated with evidence of chronic local inflammation (especially activated Microglia) A major aspect of QUIN toxicity is lipid peroxidation and markers of lipid peroxidation are found in Alzheimer's disease. Together, these data imply that QUIN may be one of the critical factors in the pathogenesis of neuronal damage in Alzheimer's disease. This review describes the multiple correlations between the KP and the neuropathogenesis of Alzheimer's disease and highlights more particularly the aspects of QUIN neurotoxicity, emphasizing its roles in lipid peroxidation and the amplification of the local inflammation

81. Haas J, Storch-Hagenlocher B, Biessmann A, Wildemann B (2002) Inducible nitric oxide synthase and argininosuccinate synthetase: co-induction in brain tissue of patients with Alzheimer's dementia and following stimulation with beta-amyloid 1-42 in vitro. Neurosci.Lett. 322:121-125
    Abstract: In Alzheimer's disease (AD), amyloid plaques within the brain are surrounded by activated glial cells (Microglia and astrocytes). The mechanisms of glial activation and its effect on disease progression are not fully understood. Growing evidence suggests that beta-amyloid (Abeta) peptide, a major constituent of the amyloid plaque, is critically involved in the induction of an inflammatory response. The goal of this study was to examine the role of Abeta in the pathogenesis of local inflammation and neuronal cell death. We found increased mRNA levels of inducible nitric oxide synthase (iNOS) and the arginine regenerating enzyme argininosuccinate synthetase (ASS) within cortices of AD patients suggesting high output NO production. In vitro, synthetic Abeta1-42 and to a lesser extent Abeta1-40 induced iNOS and ASS transcription with consecutive NO overproduction in mixed rat neuronal-glial cultures. Furthermore, Abeta-stimulation lead to an increased release of inflammatory cytokines interleukin (IL)-1beta, IL-6 and tumor necrosis factor-alpha. Again, Abeta1-42 had a much more pronounced effect as compared to Abeta1-40. Our data suggest that Abeta1-42 is a key mediator of glial activation and via the induction of inflammatory mediators may be a critical component of the neurodegenerative process in AD

82. Harman D (2002) Alzheimer's disease: role of aging in pathogenesis. Ann.N.Y.Acad.Sci. 959:384-395
    Abstract: Alzheimer's disease (AD) is characterized by intraneuronal fibrillary tangles, plaques, and cell loss. Brain lesions in both sporadic AD (SAD) and familial AD (FAD) are the same, and in the same distribution pattern, as those in individuals with Down syndrome (DS) and in smaller numbers in nondemented older individuals. Dementia onset is around 40 years for DS, 40-60 years for FAD, and usually over 60 years for SAD. The different categories of AD may be due to processes that augment to different degrees the innate cellular aging rate, that is, mitochondrial superoxide radical (SO) formation. Thus, they increase the rate of accumulation of AD lesions. This lowers the age of onset into the dementia ranges associated with DS, FAD, and SAD, and concomitantly shortens life spans. Faster aging lowers AD onset age by decreasing the onset age for neurofibrillary tangle formation and neuronal loss, and the age when brain intercellular H2O2 can activate Microglial cells. The early AD onset in DS is attributed to a defective mitochondrial complex 1. The proteins associated with FAD and their normal counterparts undergo proteolytic processing in the endoplasmic reticulum (ER). The mutated compounds increase the ratio of betaA42 to betaA40 and likely also down-regulate the ER calcium (Ca2+) buffering activity. Decreases in ER Ca2+ content should increase the mitochondrial Ca2+ pool, thus enhancing SO formation. SAD may be due to increased SO formation caused by mutations in the approximately 1000 genes involved in mitochondrial biogenesis and function. The hypothesis suggests measures to prevent and treat

83. Hayes A, Thaker U, Iwatsubo T, Pickering-Brown SM, Mann DM (2002) Pathological relationships between Microglial cell activity and tau and amyloid beta protein in patients with Alzheimer's disease. Neurosci.Lett. 331:171-174
    Abstract: The extent of Microglial cell activation (Microglial cell load) was estimated by image analysis of ferritin-immunostained sections of frontal cortex from 72 patients with pathologically confirmed Alzheimer's disease (AD), and correlated with the amount of pathological tau and amyloid beta protein (Abeta), as both Abeta(40) and Abeta(42) load, in adjacent sections of the same cases. Microglial cell load did not correlate with either Abeta(40) or Abeta(42) load but was significantly correlated with pathological tau load. Microglial cell load was unrelated to age at onset of disease or duration of illness. It is possible that because the presence of Microglial cells predates that of pathological tau proteins within the cerebral cortex in AD, neurofibrillary damage to nerve cells may stem from the release of proinflammatory and other potentially neurotoxic molecules from Microglial cells

84. Heneka MT, Galea E, Gavriluyk V, Dumitrescu-Ozimek L, Daeschner J, O'Banion MK, Weinberg G, Klockgether T, Feinstein DL (2002) Noradrenergic depletion potentiates beta -amyloid-induced cortical inflammation: implications for Alzheimer's disease. J.Neurosci. 22:2434-2442
    Abstract: Degeneration of locus ceruleus (LC) neurons and reduced levels of norepinephrine (NE) in LC projection areas are well known features of Alzheimer's disease (AD); however, the consequences of those losses are not clear. Because inflammatory mediators contribute to AD pathogenesis and because NE can suppress inflammatory gene expression, we tested whether LC loss influenced the brain inflammatory gene expression elicited by amyloid beta (Abeta). Adult rats were injected with the selective neurotoxin N-(2-chloroethyl)-N-ethyl-2 bromobenzylamine (DSP4) to induce LC death and subsequently injected in the cortex with Abeta (aggregated 1-42 peptide). DSP4 treatment potentiated the Abeta-dependent induction of inflammatory nitric oxide synthase (iNOS), interleukin (IL)-1beta, and IL-6 expression compared with control animals. In contrast, the induction of cyclooxygenase-2 expression was not modified by DSP4 treatment. In control animals, injection of Abeta induced iNOS primarily in Microglial cells, whereas in DSP4-treated animals, iNOS was localized to neurons, as is observed in AD brains. Injection of Abeta increased IL-1beta expression initially in Microglia and at later times in astrocytes, and expression levels were greater in DSP4-treated animals than in controls. The potentiating effects of DSP4 treatment on iNOS and IL-1beta expression were attenuated by coinjection with NE or the beta-adrenergic receptor agonist isoproterenol. These data demonstrate that LC loss and NE depletion augment inflammatory responses to Abeta and suggest that LC loss in AD is permissive for increased inflammation and neuronal cell death

85. Hoozemans JJ, Veerhuis R, Janssen I, van Elk EJ, Rozemuller AJ, Eikelenboom P (2002) The role of cyclo-oxygenase 1 and 2 activity in prostaglandin E(2) secretion by cultured human adult Microglia: implications for Alzheimer's disease. Brain Res. 951:218-226
    Abstract: Microglial cyclo-oxygenase (COX) expression is considered to be important in the pathogenesis of Alzheimer's disease (AD) and, therefore, constitutes a key target for therapeutic intervention. We investigated the influence of AD plaque associated factors on COX-1 and COX-2 expression and activity in adult human Microglial cells in vitro. COX-2 immunoreactivity and mRNA were induced by lipopolysaccharide (LPS), not by AD plaque associated cytokines interleukin (IL)-1alpha, IL-1beta, IL-6, tumor necrosis factor (TNF)-alpha, or amyloid (A)beta(1-42). To assess functional COX activity, the release of PGE(2) into the culture medium was determined. LPS and also arachidonic acid (AA) dose-dependently stimulated PGE(2) release. The effects of AA are independent from induction of COX mRNA expression, or of de novo protein synthesis. No effects of either plaque-associated cytokines or Abeta(1-42) on PGE(2) secretion were seen, even when cells were co-stimulated with AA, to provide enough substrate. COX isotype selective inhibitors were used to discern relative contributions of COX-1 and COX-2 activities to Microglial PGE(2) secretion. COX-2 and in part COX-1-selective inhibitors inhibited LPS-induced PGE(2) secretion, whereas the AA-induced PGE(2) secretion was reduced by COX-1-selective inhibitors only. Apparently, adult human Microglia in vitro (1) constitutively express COX-1, and (2) do not express COX-2 upon exposure to either Abeta or plaque associated cytokines. In the light of Microglial COX activity as a potential therapeutical target in AD, the data presented in this study suggest that classical NSAIDs, rather than selective COX-2 inhibitors, are more potent in reducing Microglial prostaglandin secretion

86. Hull M, Hampel H (2002) Neuroinflammation in Alzheimer's disease: potential targets for disease-modifying drugs. Ernst.Schering.Res.Found.Workshop159-178

87. Hull M, Lieb K, Fiebich BL (2002) Pathways of inflammatory activation in Alzheimer's disease: potential targets for disease modifying drugs. Curr.Med.Chem. 9:83-88
    Abstract: In the human brain several cell types are capable of initiating and amplifying a brain specific inflammatory response involving the synthesis of cytokines, prostaglandins and oxygen free radicals. In Alzheimer's disease (AD), signs of an inflammatory activation of Microglia and astroglia are present inside and outside amyloid deposits. Cell culture and animal models suggest an interactive relationship between inflammatory activation, reduced neuronal functioning and deposition of amyloid. The activation of inflammation-associated enzymes such as p38 mitogen-activated protein kinase (p38 MAPK) and cycloxygenase-2 (COX-2) is not restricted to glial cells but also found in neurons and may contribute to intraneuronal damage. Epidemiological studies have shown a reduced risk of AD among users of anti-inflammatory drugs. Therefore, anti-inflammatory drugs have become the focus of several new treatment strategies. Small clinical trials with non-steroidal anti-inflammatory drugs (NSAIDs) such as indomethacin and diclofenac showed a trend for a disease modifying effect, while clinical trials with steroids did not show a beneficial effect. NSAIDs may not only act on COX-2 but also inhibit COX-1 activity or activate peroxisome proliferator-activated receptor gamma (PPAR gamma). Among promising new strategies to reduce the inflammatory activation in the CNS interfering with intracellular pro-inflammatory pathways has been shown to be effective in various cell culture and animal models. Inhibitors of p38MAPK and PPAR gamma agonists may be suitable agents to suppress inflammatory activation in AD

88. Infante J, Llorca J, Berciano J, Combarros O (2002) No synergistic effect between -850 tumor necrosis factor-alpha promoter polymorphism and apolipoprotein E epsilon 4 allele in Alzheimer's disease. Neurosci.Lett. 328:71-73
    Abstract: In the brains of Alzheimer's disease (AD) patients, Microglia cells are activated and produce inflammatory mediators such as tumor necrosis factor-alpha (TNF-alpha). A recent study conducted in Northern Ireland showed that a polymorphism in the promotor region (-850) of the TNF-alpha gene increased the risk of AD associated with carriage of the apolipoprotein E (APOE) epsilon 4 allele. In a case-control study restricted to a population from Northern Spain and utilizing 321 sporadic AD patients and 312 control subjects, we have found that the -850 TNF-alpha polymorphism does not interact with the APOE gene to increase the risk associated with the epsilon 4 allele

89. 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

90. Jantzen PT, Connor KE, DiCarlo G, Wenk GL, Wallace JL, Rojiani AM, Coppola D, Morgan D, Gordon MN (2002) Microglial activation and beta -amyloid deposit reduction caused by a nitric oxide-releasing nonsteroidal anti-inflammatory drug in amyloid precursor protein plus presenilin-1 transgenic mice. J.Neurosci. 22:2246-2254
    Abstract: 3-4-(2-Fluoro-alpha-methyl-[1,1'-biphenyl]-4-acetyloxy)-3-methoxyphenyl]-2 -propenoic acid 4-nitrooxy butyl ester (NCX-2216), a nitric oxide (NO)-releasing derivative of the cyclooxygenase-1-preferring nonsteroidal anti-inflammatory drug (NSAID) flurbiprofen, dramatically reduced both beta-amyloid (Abeta) loads and Congo red staining in doubly transgenic (Tg) amyloid precursor protein plus presenilin-1 mice when administered at 375 ppm in diet between 7 and 12 months of age. This reduction was associated with a dramatic increase in the number of Microglia expressing major histocompatibility complex-II antigen, a marker for Microglial activation. In contrast, ibuprofen at 375 ppm in diet caused modest reductions in Abeta load but not Congo red staining, suggesting that the effects of this nonselective NSAID were restricted primarily to nonfibrillar deposits. We detected no effects of the cyclooxygenase-2-selective NSAID celecoxib at 175 ppm on amyloid deposition. In short-term studies of 12-month-old Tg mice, we found that the Microglia-activating properties of NCX-2216 (7.5 mg small middle dot kg(-1) small middle dot d(-1), s.c.) were present after 2 weeks of treatment. Microglia were not activated by NCX-2216 in non-Tg mice lacking Abeta deposits, nor were Microglia activated in Tg animals by flurbiprofen (5 mg small middle dot kg(-1) small middle dot d(-1)) alone. These data are consistent with the argument that activated Microglia can clear Abeta deposits. We conclude that the NO-generating component of NCX-2216 confers biological actions that go beyond those of typical NSAIDs. In conclusion, NCX-2216 is more efficacious than ibuprofen or celecoxib in clearing Abeta deposits from the brains of Tg mice, implying potential benefit in the treatment of Alzheimer's dementia

91. Jordan-Sciutto KL, Malaiyandi LM, Bowser R (2002) Altered distribution of cell cycle transcriptional regulators during Alzheimer disease. J.Neuropathol.Exp.Neurol. 61:358-367
    Abstract: A number of mechanisms have been proposed to contribute to the selective neuronal cell loss observed during Alzheimer disease (AD). These include the formation and accumulation of amyloid-beta (Abeta)-containing plaques, neurofibrillary tangles (NFTs), and inflammatory processes mediated by astrocytes and Microglia. Neuronal responses to such insults in AD brain include increased protein levels and immunoreactivity for kinases known to regulate cell cycle progression. One down-stream target of these cell cycle regulatory proteins, the Retinoblastoma susceptibility gene product (pRb), has been shown to exhibit altered expression patterns in AD. Furthermore, in vitro studies have implicated pRb and one of the transcription factors it regulates, E2F1, in Abeta-induced cell death. To further explore the role of these proteins in AD, we examined the distribution of the E2F1 transcription factor and the hyperphosphorylated form of pRb (ppRb), which is unable to bind and regulate E2F activity, in the cortex of patients with AD and in non-demented controls. We observed increased ppRb and E2FI immunoreactivity in AD brain, with ppRb predominately located in the nucleus and E2F1 in the cytoplasm. Although neither of these proteins significantly co-localized with NFTs, both ppRb and E2F1 were found in cells surrounding a subset of Abeta-containing plaques. These results support a role for G1 to S phase cell cycle regulators in AD

92. Kakimura J, Kitamura Y, Takata K, Umeki M, Suzuki S, Shibagaki K, Taniguchi T, Nomura Y, Gebicke-Haerter PJ, Smith MA, Perry G, Shimohama S (2002) Microglial activation and amyloid-beta clearance induced by exogenous heat-shock proteins. FASEB J. 16:601-603
    Abstract: Alzheimer's disease (AD) is characterized by the accumulation of fibrillar amyloid-beta (Abeta) peptides to form amyloid plaques. Understanding the balance of production and clearance of Abeta peptides is the key to elucidating amyloid plaque homeostasis. Microglia in the brain, associated with senile plaques, are likely to play a major role in maintaining this balance. Here, we show that heat-shock proteins (HSPs), such as HSP90, HSP70, and HSP32, induce the production of interleukin 6 and tumor necrosis factor alpha and increase the phagocytosis and clearance of Abeta peptides. This suggests that Microglial interaction with Abeta peptides is highly regulated by HSPs. The mechanism of Microglial activation by exogenous HSPs involves the nuclear factor kB and p38 mitogen-activated protein kinase pathways mediated by Toll-like receptor 4 activation. In AD brains, levels of HSP90 were increased in both the cytosolic and membranous fractions, and HSP90 was colocalized with amyloid plaques. These observations suggest that HSP-induced Microglial activation may serve a neuroprotective role by facilitating Abeta clearance and cytokine production

93. Klegeris A, McGeer PL (2002) Cyclooxygenase and 5-lipoxygenase inhibitors protect against mononuclear phagocyte neurotoxicity. Neurobiol.Aging 23:787-794
    Abstract: Neuroinflammation and oxidative stress are believed to be contributing factors to neurodegeneration in normal aging, as well as in age-related neurological disorders. Reactive Microglia are found in increased numbers in aging brain and are prominently associated with lesions in such age-related degenerative conditions as Alzheimer's disease (AD), Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS). In vitro, stimulated Microglia or Microglial-like cells secrete neurotoxic materials and are generators of free radicals through their respiratory burst system. Agents that suppress Microglial activation are therefore candidates for neuroprotection. We have developed quantitative in vitro assays for measuring neurotoxicity of Microglia or other mononuclear phagocytes. Neuronal like SH-SY5Y cells are cultured in supernatants from activated cells of the human monocytic THP-1 line and their survival is followed. Respiratory burst is directly measured on the activated cells. We tested inhibitors of the cyclooxygenase (COX) or the 5-lipoxygenase (5-LOX) pathways as possible neuroprotective agents. The COX pathway generates inflammatory prostaglandins, while the 5-LOX pathway generates inflammatory leukotrienes. We found that inhibitors of both these pathways suppressed neurotoxicity in a dose-dependent fashion. They included the COX-1 inhibitor indomethacin; the COX-2 inhibitor NS-398; the mixed COX-1/COX-2 inhibitor ibuprofen; the nitric oxide (NO) derivatives of indomethacin, ibuprofen and flurbiprofen; the 5-LOX inhibitor REV 5901; and the 5-LOX activating protein (FLAP) inhibitor MK-886. The FLAP inhibitor also reduced respiratory burst activity in a more potent manner than indomethacin. Combinations of COX and 5-LOX inhibitors were more effective than single inhibitors. The data suggest that both COX inhibitors and 5-LOX inhibitors may be neuroprotective in vivo by suppressing toxic actions of Microglia/macrophages, and that combinations of the two might have greater therapeutic potential than single inhibitors of either class

94. Koistinaho M, Kettunen MI, Goldsteins G, Keinanen R, Salminen A, Ort M, Bures J, Liu D, Kauppinen RA, Higgins LS, Koistinaho J (2002) Beta-amyloid precursor protein transgenic mice that harbor diffuse A beta deposits but do not form plaques show increased ischemic vulnerability: role of inflammation. Proc.Natl.Acad.Sci.U.S.A 99:1610-1615
    Abstract: beta-amyloid (A beta), derived form the beta-amyloid precursor protein (APP), is important for the pathogenesis of Alzheimer's disease (AD), which is characterized by progressive decline of cognitive functions, formation of A beta plaques and neurofibrillary tangles, and loss of neurons. However, introducing a human wild-type or mutant APP gene to rodent models of AD does not result in clear neurodegeneration, suggesting that contributory factors lowering the threshold of neuronal death may be present in AD. Because brain ischemia has recently been recognized to contribute to the pathogenesis of AD, we studied the effect of focal brain ischemia in 8- and 20-month-old mice overexpressing the 751-amino acid isoform of human APP. We found that APP751 mice have higher activity of p38 mitogen-activated protein kinase (p38 MAPK) in Microglia, the main immune effector cells within the brain, and increased vulnerability to brain ischemia when compared with age-matched wild-type mice. These characteristics are associated with enhanced Microglial activation and inflammation but not with altered regulation of cerebral blood flow, as assessed by MRI and laser Doppler flowmetry. Suppression of inflammation with aspirin or inhibition of p38 MAPK with a selective inhibitor, SD-282, abolishes the increased neuronal vulnerability in APP751 transgenic mice. SD-282 also suppresses the expression of inducible nitric-oxide synthase and the binding activity of activator protein 1. These findings elucidate molecular mechanisms of neuronal injury in AD and suggest that antiinflammatory compounds preventing activation of p38 MAPK in Microglia may reduce neuronal vulnerability in AD

95. Kubo T, Nishimura S, Kumagae Y, Kaneko I (2002) In vivo conversion of racemized beta-amyloid ([D-Ser 26]A beta 1-40) to truncated and toxic fragments ([D-Ser 26]A beta 25-35/40) and fragment presence in the brains of Alzheimer's patients. J.Neurosci.Res. 70:474-483
    Abstract: The lag between beta-amyloid (A beta) deposition and neurodegeneration in Alzheimer's disease (AD) suggests that age-dependent factors are involved in the pathogenesis. Racemization of Ser and Asp in A beta is a typical age-dependent modification in AD. We have shown recently that A beta1-40 racemized at Ser(26) ([D-Ser(26)]A beta 1-40) is soluble and non-toxic to neuronal cells, but is easily converted by brain proteases to truncated toxic fragments, [D-Ser(26)]A beta 25-35/40. Furthermore, [D-Ser(26)]A beta1-40 in vivo, produced a drastic and synergistic neuronal loss by enhancing the excitotoxicity when co-injected into rat hippocampus with ibotenic acid, an excitatory amino acid, suggesting an in vivo conversion of non-toxic [D-Ser(26)]A beta1-40 to toxic fragments including [D-Ser(26)]A beta 25-35/40. In this study, we further investigated the mechanism behind the in vivo neuronal loss by [D-Ser(26)]A beta1-40 and ibotenic acid in rats, and also searched for the presence of [D-Ser(26)]A beta 25-35/40 antigens in AD brains. Quantitative analyses of the damaged area indicate clearly that non-toxic [D-Ser(26)]A beta 1-40 caused as much neurodegeneration as toxic [D-Ser(26)]A beta 25-35/40. MK-801, an NMDA receptor antagonist, completely inhibited the neurodegeneration. The immunohistochemical analyses using anti-[D-Ser(26)]A beta 25-35/40-specific antibodies demonstrated the presence of [D-Ser(26)]A beta 25-35/40 antigens in senile plaques and in degenerating hippocampal CA1 neurons in AD brains, but not in age-matched control brains. These results strengthen our hypothesis that soluble [D-Ser(26)]A beta1-40, possibly produced during aging, is released from plaques and converted by proteolysis to toxic [D-Ser(26)]A beta 25-35/40, which damage hippocampal CA1 neurons by enhancing excitotoxicity in AD. This may account for the lag between A beta deposition and neurodegeneration in AD

96. Lee J, Chan SL, Mattson MP (2002) Adverse effect of a presenilin-1 mutation in Microglia results in enhanced nitric oxide and inflammatory cytokine responses to immune challenge in the brain. Neuromolecular.Med. 2:29-45
    Abstract: Inflammatory processes involving glial cell activation are associated with amyloid plaques and neurofibrillary tangles, the cardinal neuropathological lesions in the brains of Alzheimer's disease (AD) patients, However, it is unclear whether these inflammatory processes occur as a response to neuronal degeneration or might represent more seminal events in the disease process. Some cases of AD are caused by mutations in presenilin-1 (PS1), and it has been shown that PS1 mutations perturb neuronal calcium homeostasis, promote increased production of amyloid beta-peptide (Abeta), and render neurons vulnerable to synaptic dysfunction, excitotoxicity, and apoptosis. Although glial cells express PS1, it is not known if PS1 mutations alter glial cell functions. We now report on studies of glial cells in PS1 mutant knockin mice that demonstrate an adverse effect PS1 mutations in Microglial cells. Specifically, PS1 mutant mice exhibit an enhanced inflammatory cytokine response to immune challenge with bacterial lipopolysaccharide (LPS). LPS-induced levels of mRNAs encoding tumor necrosis fctor-alpha (TNFalpha), interleukin (IL)-1alpha, IL-1beta, IL-1 receptor antagonist, and IL-6 are significantly greater in the hippocampus and cerebral cortex of PS1 mutant mice as compared to wild-type mice. In contrast, the cytokine responses to LPS in the spleen is unaffected by the PS1 mutation. Studies of cultured Microglia from PS1 mutant and wild-type mice reveal that PS1 is expressed in Microglia and that the PS1 mutation confers a heightened sensitivity to LPS, as indicated by superinduction of inducible nitric oxide synthase (NOS) and activation of mitogen-activated protein kinase (MAPK). These findings demonstrate an adverse effect of PS1 mutations on Microglial cells that results in their hyperactivation under pro-inflammatory conditions, which may, together with direct effects of mutant PS1 in neurons, contribute to the neurodegenerative process in AD. These findings also have important implications for development of a "vaccine" for the prevention or treatment of AD

97. Lee YB, Nagai A, Kim SU (2002) Cytokines, chemokines, and cytokine receptors in human Microglia. J.Neurosci.Res. 69:94-103
    Abstract: Enriched populations of human Microglial cells were isolated from mixed cell cultures prepared from embryonic human telencephalon tissues. Human Microglial cells exhibited cell type-specific antigens for macrophage-Microglia lineage cells including CD11b (Mac-1), CD68, B7-2 (CD86), HLA-ABC, HLA-DR and ricinus communis aggulutinin lectin-1 (RCA-1), and actively phagocytosed latex beads. Gene expression and protein production of cytokines, chemokines and cytokine/chemokine receptors were investigated in the purified populations of human Microglia. Normal unstimulated human Microglia expressed constitutively mRNA transcripts for interleukin- 1beta (IL-1beta) -6, -8, -10, -12, -15, tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-1alpha (MIP-1alpha), MIP-1beta, and monocyte chemoattractant protein-1 (MCP-1), while treatment with lipopolysaccharide (LPS) or amyloid beta peptides (Abeta) led to increased expression of mRNA levels of IL-8, IL-10, IL-12, TNF-alpha, MIP-1alpha, MIP-1beta, and MCP-1. Human Microglia, in addition, expressed mRNA transcripts for IL-1RI, IL-1RII, IL-5R, IL-6R, IL-8R, IL-9R, IL-10R, IL-12R, IL-13R, and IL-15R. Enzyme-linked immunosorbent assays (ELISA) showed increased protein levels in culture media of IL-1beta, IL-8, TNF-alpha, and MIP-1alpha in human Microglia following treatment with LPS or Abeta. Increased TNF-alpha release from human Microglia following LPS treatment was completely inhibited with IL-10 pretreatment, but not with IL-6, IL-9, IL-12, IL-13, or transforming growth factor-beta (TGF-beta). Present results should help in understanding the basic Microglial biology, but also the pathophysiology of activated Microglia in neurological diseases such as Alzheimer disease, Parkinson disease, Huntington disease, amyotrophic lateral sclerosis, stroke, and neurotrauma

98. Lue LF, Walker DG (2002) Modeling Alzheimer's disease immune therapy mechanisms: interactions of human postmortem Microglia with antibody-opsonized amyloid beta peptide. J.Neurosci.Res. 70:599-610
    Abstract: The induction of an antibody response to amyloid beta (Abeta) peptide has become a strategy for the treatment of Alzheimer's disease (AD). This has proven effective in reducing the plaque burden in transgenic mice that develop Abeta plaques similar to human AD patients. The mechanism for enhanced clearance of Abeta is partly due to the interaction of immunoglobulin Fcgamma receptor-expressing Microglia and specific antibody-opsonized Abeta deposits. This interaction can stimulate Fcgamma receptor-mediated phagocytosis, but also results in inflammatory activation of these cells. Consequently, interaction of Microglia with antibody-antigen complexes could exacerbate the existing inflammation in the brains of AD patients. In this study, we used substrate-bound Abeta and cultured human Microglia from AD and non-demented cases to model interaction of Microglia and antibody-opsonized plaques in AD brains. Enhanced production of tumor necrosis factor-alpha, macrophage colony stimulating factor, interleukin-10, and superoxide ions was detected. We also demonstrated enhanced uptake of opsonized Abeta by Microglia, which was reduced significantly in the presence of excess IgG, indicative of the involvement of Fcgamma receptor-mediated mechanisms. Human Microglia were shown in this study to express mRNA for Fcgamma receptors I, IIa, IIb, and III. The expression of Fcgamma receptor II was augmented by proinflammatory stimulation. These results suggest that initial interactions of human Microglia with antibody-opsonized amyloid could result in increased inflammation. The consequence of this on inflammatory pathology in AD brains needs to be considered before immunization is used as a strategy for treating AD

99. Mattson MP (2002) Oxidative stress, perturbed calcium homeostasis, and immune dysfunction in Alzheimer's disease. J.Neurovirol. 8:539-550
    Abstract: Although Alzheimer's disease (AD) may not involve a transmissible agent, it does involve a pathogenic process similar to that of transmissible prion disorders (both involve a protein that adopts an abnormal pathogenic conformation in which it self-aggregates, forming amyloid deposits in and surrounding neurons) and viral dementias such as human immunodeficiency virus (HIV) encephalitis. The clinical presentation of patients with AD is dominated by cognitive deficits and emotional disturbances that result from dysfunction and degeneration of neurons in the limbic system and cerebral cortex. The pathogenic process in the brain involves deposition of insoluble aggregates of amyloid beta-peptide, oxidative stress and calcium dysregulation in neurons, and activation of inflammatory cytokine cascades involving Microglia. However, AD patients also exhibit alterations in immune function. Studies of lymphocytes and lymphoblast cell lines from AD patients and age-matched normal control patients have documented alterations in cytokine and calcium signaling and increased levels of oxidative stress in immune cells from the AD patients. Studies of the pathogenic actions of mutations in presenilins and amyloid precursor protein that cause early-onset familial AD have established central roles for perturbed cellular calcium homeostasis and oxidative stress in the neurodegenerative process. Presenilin and amyloid precursor protein (APP) mutations also increase oxidative stress and perturb calcium signaling in lymphocytes in ways that alter their production of cytokines that are critical for proper immune responses. Immune dysfunction occurs prior to clinical symptoms in mouse models of AD, and brain cytokine responses to immune challenge are altered in presenilin mutant mice, suggesting a causal role for altered immune function in the disease process. Interestingly, immunization of AD mice with amyloid beta-peptide can stimulate the immune system to remove amyloid from the brain and can ameliorate memory deficits, suggesting that it may be possible to prevent AD by bolstering immune function

100. McGeer PL, McGeer EG (2002) Local neuroinflammation and the progression of Alzheimer's disease. J.Neurovirol. 8:529-538
     Abstract: Postmortem immunohistochemical studies have revealed a state of chronic inflammation limited to lesioned areas of brain in Alzheimer's disease. Some key actors in this inflammation are activated Microglia (brain macrophages), proteins of the classical complement cascade, the pentraxins, cytokines, and chemokines. The inflammation does not involve the adaptive immune system or peripheral organs, but is rather due to the phylogenetically much older innate immune system, which appears to operate in most tissues of the body. Chronic inflammation can damage host tissue and the brain may be particularly vulnerable because of the postmitotic nature of neurons. Many of the inflammatory mediators have been shown to be locally produced and selectively elevated in affected regions of Alzheimer's brain. Moreover, studies of tissue in such degenerative processes as atherosclerosis and infarcted heart suggest a similar local innate immune reaction may be important in such conditions. Much epidemiological and limited clinical evidence suggests that nonsteroidal anti-inflammatory drugs may impede the onset and slow the progression of Alzheimer's disease. But these drugs strike at the periphery of the inflammatory reaction. Much better results might be obtained if drugs were found that could inhibit the activation of Microglia or the complement system in brain, and combinations of drugs aimed at different inflammatory targets might be much more effective than single agents

101. McGeer PL, McGeer EG (2002) The possible role of complement activation in Alzheimer disease. Trends Mol.Med. 8:519-523
     Abstract: Molecular pathological studies of Alzheimer disease (AD) brain have revealed the presence of a spectrum of inflammatory mediators. Epidemiological studies have indicated that the use of anti-inflammatory agents, especially non-steroidal anti-inflammatory drugs (NSAIDs), results in a substantially reduced risk of contracting the disease. It is possible that well targeted anti-inflammatory agents will also be useful in treating established AD. Inhibitors of cyclooxygenase-2 have been unsuccessful in this regard, and traditional NSAIDs have produced mixed results. The complement system, which is strongly activated in AD brain, is an attractive target for therapeutic intervention, particularly through inhibition of the autodestructive action of the membrane attack complex. The complement system works in conjunction with activated Microglia, which express high levels of complement receptors. Overactive Microglia secrete many toxic materials. Inhibition of Microglial activation is another potential therapeutic target

102. Miguel-Hidalgo JJ, Alvarez XA, Cacabelos R, Quack G (2002) Neuroprotection by memantine against neurodegeneration induced by beta-amyloid(1-40). Brain Res. 958:210-221
     Abstract: Progressive neuronal loss and cognitive decline in Alzheimer's disease (AD) might be aggravated by beta-amyloid-enhanced excitotoxicity. Memantine is an uncompetitive NMDA receptor antagonist under clinical development for the treatment of AD. Memantine has neuroprotective actions in several in vitro and in vivo models. In the present study, we determined whether memantine protected against beta-amyloid induced neurotoxicity and learning impairment in rats. Twenty Sprague-Dawley rats received vehicle or vehicle plus memantine (steady-state plasma concentrations of 2.34+/-0.23 microM, n=10) s.c. by osmotic pump for 9 days. After 2 days of treatment, 2 microl of water containing beta-amyloid 1-40 [Abeta(1-40)] were injected into the hippocampal fissure. On the ninth day of treatment, animals were sacrificed, and morphological and immunohistochemical techniques were used to determine the extent of neuronal degeneration and astrocytic and Microglial activation in the hippocampus. Psychomotor activity and spatial discrimination were tested on the eighth day of treatment. Abeta(1-40), but not water, injections into hippocampus led to neuronal loss in the CA1 subfield, evidence of widespread apoptosis, and astrocytic and Microglial activation and hypertrophy. Memantine treated animals had significant reductions in the amount of neuronal degeneration, pyknotic nuclei, and GFAP immunostaining as compared with vehicle treated animals. These data suggest that memantine, at therapeutically relevant concentrations, can protect against neuronal degeneration induced by beta-amyloid

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

104. Munch G, Robinson SR (2002) Potential neurotoxic inflammatory responses to Abeta vaccination in humans. J.Neural Transm. 109:1081-1087
     Abstract: Studies in transgenic mouse models of Alzheimer's disease suggested the development of a vaccine that would induce the production of antibodies against amyloid-beta (Abeta) peptide, which in turn would stimulate Microglia to phagocytose and remove senile plaques. However, some patients in the human clinical trials developed symptoms of brain inflammation, demonstrated by lymphocyte infiltration and elevated protein levels. These parameters are indicative of a breakdown of the blood-brain-barrier and entry of T-cells into the brain. Abeta-specific activated T-helper cells have the potential to amplify the existing pro-inflammatory conditions that are present in the brains of Alzheimer's disease patients. Cytotoxic T-cells might even attack the amyloid precursor protein which is present on the surface of many cells, including neurons. Before undertaking further vaccination trials there is a need to re-assess the risks associated with Abeta vaccination and with the therapeutic containment of a neuroinflammatory response. These risks may not be justified in the light of recent studies which have shown the efficacy of conventional, low-risk treatments in slowing the progress of AD

105. Naidu A, Xu Q, Catalano R, Cordell B (2002) Secretion of apolipoprotein E by brain glia requires protein prenylation and is suppressed by statins. Brain Res. 958:100-111
     Abstract: Apolipoprotein E (ApoE) genotype modulates the risk of Alzheimer's disease. ApoE has been shown essential for amyloid beta-peptide fibrillogenesis and deposition, a defining pathological feature of this disease. Because astrocytes and Microglia represent the major source of extracellular apoE in brain, we investigated apoE secretion by glia. We determined that protein prenylation is required for apoE release from a continuous Microglial cell line, primary mixed glia, and from organotypic hippocampal cultures. Using selective protein prenylation inhibitors, apoE secretion was found to require protein geranylgeranylation. This prenylation involved a protein critical to apoE secretion, not apoE proper. ApoE secretion could also be suppressed by inhibiting synthesis of mevalonate, the precursor to both types of protein prenylation, using hydroxyl-3-methylglutaryl coenzyme A reductase inhibitors (statins). Recent reports have described the beneficial effects of statins on the risk of dementia. Our finding that protein geranylgeranylation is required for apoE secretion in the brain parenchyma provides another contributing mechanism to explain the effective properties of statins against the development of dementia. In this model, statin-mediated inhibition of mevalonate synthesis, an essential reaction in forming geranylgeranyl lipid, would lower extracellular levels of parenchymal apoE. Because apoE has been found necessary for plaque development in transgenic models of Alzheimer's disease, suppressing apoE secretion by statins could reduce plaques and, in turn, improve cognitive function

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

107. Pocock JM, Liddle AC, Hooper C, Taylor DL, Davenport CM, Morgan SC (2002) Activated Microglia in Alzheimer's disease and stroke. Ernst.Schering.Res.Found.Workshop105-132

108. Rogers J, Lue LF, Walker DG, Yan SD, Stern D, Strohmeyer R, Kovelowski CJ (2002) Elucidating molecular mechanisms of Alzheimer's disease in Microglial cultures. Ernst.Schering.Res.Found.Workshop25-44

109. Rogers J, Strohmeyer R, Kovelowski CJ, Li R (2002) Microglia and inflammatory mechanisms in the clearance of amyloid beta peptide. Glia 40:260-269
     Abstract: There is now abundant evidence that brain Microglia, when activated, have the lineage, receptors, and synthetic capacity to participate in both potentially neurotoxic inflammatory responses and potentially beneficial phagocytic responses. Amyloid beta peptide (Abeta) forms highly insoluble, beta-pleated aggregates that are widely deposited in the Alzheimer's disease (AD) cortex and limbic system. Aggregated Abeta also activates the classical and alternative complement cascades. These properties make Abeta an excellent target for Microglial phagocytosis, a view supported by multiple reports, through well established mechanisms of phagocyte clearance

110. Sai X, Kawamura Y, Kokame K, Yamaguchi H, Shiraishi H, Suzuki R, Suzuki T, Kawaichi M, Miyata T, Kitamura T, De Strooper B, Yanagisawa K, Komano H (2002) Endoplasmic reticulum stress-inducible protein, Herp, enhances presenilin-mediated generation of amyloid beta-protein. J.Biol.Chem. 277:12915-12920
     Abstract: Presenilin (PS) is essential for the gamma-cleavage required for the generation of the C terminus of amyloid beta-protein (Abeta). However, the mechanism underlying PS-mediated gamma-cleavage remains unclear. We have identified Herp cDNA by our newly developed screening method for the isolation of cDNAs that increase the degree of gamma-cleavage. Herp was originally identified as a homocysteine-responsive protein, and its expression is up-regulated by endoplasmic reticulum stress. Herp is an endoplasmic reticulum-localized membrane protein that has a ubiquitin-like domain. Here, we report that a high expression of Herp in cells increases the level of Abeta generation, although not in PS-deficient cells. We found that Herp interacts with both PS1 and PS2. Thus, Herp regulates PS-mediated Abeta generation, possibly through its binding to PS. Immunohistochemical analysis of a normal human brain section with an anti-Herp antibody revealed the exclusive staining of neurons and vascular smooth muscle cells. Moreover, the antibody strongly stained activated Microglia in senile plaques in the brain of patients with Alzheimer disease. Taken together, Herp could be involved in Abeta accumulation, including the formation of senile plaques and vascular Abeta deposits

111. Sasaki A, Shoji M, Harigaya Y, Kawarabayashi T, Ikeda M, Naito M, Matsubara E, Abe K, Nakazato Y (2002) Amyloid cored plaques in Tg2576 transgenic mice are characterized by giant plaques, slightly activated Microglia, and the lack of paired helical filament-typed, dystrophic neurites. Virchows Arch. 441:358-367
     Abstract: We examined the brains of Tg2576 transgenic mice carrying human amyloid precursor protein with the Swedish mutation and Alzheimer's disease (AD) by means of immunohistochemistry and electron microscopy to clarify the characteristics of amyloid-associated pathology in the transgenic mice. In 12- to 29-month-old Tg2576 mice, congophilic cored plaques in the neocortex and hippocampus were labeled by all of the Abeta1-, Abeta40- and 42-specific antibodies, as seen in the classical plaques in AD. However, large-sized (>50 micro m in core diameter) plaques were seen more frequently in the older mice (18-29 months) than in those with AD (approximately 20% vs 2% in total cored plaques), and Tg2576 mice contained giant plaques (>75 micro m in core diameter), which were almost never seen in the brain of those with AD. Neither thread-like structures nor peripheral coronas were observed in the cored plaques of the transgenic mice in the silver impregnations. Immunohistochemically, plaque-accompanied Microglia showed a slight enlargement of the cytoplasm with consistent labeling of Mac-1 and macrosialin (murine CD68), and with partial labeling of Ia antigen and macrophage-colony stimulating factor receptor. Ultrastructurally, the Microglia surrounding the extracellular amyloid fibrils in the large, cored plaques showed some organella with phagocytic activity, such as secondary lysosomal, dense bodies, but intracellular amyloid fibrils were not evident. Dystrophic neurites in the plaques of the transgenic mice contained many dense multilaminar bodies, but no paired helical filaments. Our results suggest that giant cored plaques without coronas or paired helical filament-typed, dystrophic neurites are characteristic in Tg2576 mice, and that plaque-associated Microglia in transgenic mice are activated to be in phagocytic function but not sufficient enough to digest extracellularly deposited amyloid fibrils

112. Schenk DB, Yednock T (2002) The role of Microglia in Alzheimer's disease: friend or foe? Neurobiol.Aging 23:677-679

113. Seiler N (2002) Ammonia and Alzheimer's disease. Neurochem.Int. 41:189-207
     Abstract: Alzheimer's disease (AD) is the most common age-related neurodegenerative disorder. Behavioural, cognitive and memory dysfunctions are characteristic symptoms of AD. The formation of amyloid plaques is currently considered as the key event of AD. Other histological hallmarks of the disease are the formation of fibrillary tangles, astrocytosis, and loss of certain neuronal systems in cortical areas of the brain. A great number of possible aetiologic and pathogenetic factors of AD have been published in the course of the last two decades. Among the toxic factors, which have been considered to contribute to the symptoms and progression of AD, ammonia deserves special interest for the following reasons: (a) Ammonia is formed in nearly all tissues and organs of the vertebrate organism; it is the most common endogenous neurotoxic compounds. Its effects on glutamatergic and GABAergic neuronal systems, the two prevailing neuronal systems of the cortical structures, are known for many years. (b) The impairment of ammonia detoxification invariably leads to severe pathology. Several symptoms and histologic aberrations of hepatic encephalopathy (HE), of which ammonia has been recognised as a pathogenetic factor, resemble those of AD. (c) The excessive formation of ammonia in the brains of AD patients has been demonstrated, and it has been shown that some AD patients exhibit elevated blood ammonia concentrations. (d) There is evidence for the involvement of aberrant lysosomal processing of beta-amyloid precursor protein (beta-APP) in the formation of amyloid deposits. Ammonia is the most important natural modulator of lysosomal protein processing. (e) Inflammatory processes and activation of Microglia are widely believed to be implicated in the pathology of AD. Ammonia is able to affect the characteristic functions of Microglia, such as endocytosis, and cytokine production. Based on these facts, an ammonia hypothesis of AD has first been suggested in 1993. In the present review old and new observations are discussed, which are in support of the notion that ammonia is a factor able to produce symptoms of AD and to affect the progression of the disease

114. Shirabe T, Irie K, Uchida M (2002) Autopsy case of aluminum encephalopathy. Neuropathology. 22:206-210
     Abstract: We report the case of a 59-year-old female aluminum encephalopathy patient who had chronic renal failure and took 3.0 g hydroxy-aluminum gel per day for the control of serum phosphorus level during a 15-year period. Nine months before her death she developed disorientation, memory disturbance, emotional incontinence, general convulsions and consciousness disturbance. Neuropathologically, the brain showed nerve cell atrophy and mild loss with stromal spongiosis, proliferation of astrocytes and Microglia in the cerebral cortex, basal ganglia and thalamus. Some nerve cells were stained immunohistochemically by phosphorylated neurofilament, but apparent neurofibrillary tangles were not observed. Aluminum was detected in the nerve cells of the cerebral cortex by X-ray microanalysis. Despite the long-term intake of aluminum, there were no neuropathological findings of Alzheimer's disease. The findings in our case suggested that aluminum alone might not develop Alzheimer's disease

115. Sinigaglia-Coimbra R, Cavalheiro EA, Coimbra CG (2002) Postischemic hyperthermia induces Alzheimer-like pathology in the rat brain. Acta Neuropathol.(Berl) 103:444-452
     Abstract: This study addresses the effects of induced hyperthermia on post-ischemic rat brain evaluated histologically and/or immunohistochemically after 7-day, 2-month or 6-month survival. Hyperthermia (38.5 degrees - 40 degrees C) maintained (by heating the cage environment to 34-35 degrees C) for two consecutive periods of 5 and 9 h timed, respectively, from 4- and 21-h recirculation following 10-min global ischemia (two-vessel occlusion + hypotension) induced chronic neuronal death that became apparent in the rat forebrain from 7-day to 2-month survival. Associated immunohistochemical findings after 2 or 6 months of recovery included: (1) complement activation (membrane attack complex formation); (2) generalized overexpression of ubiquitin in surviving forebrain neurons; (3) persistent activation of macrophages; (4) presence of gemistocytic astrocytes in the hippocampus; (5) maturation of amyloid plaques (identified by immunohistochemistry using anti-human beta-A4 primary antibody) in cerebral cortex; and (6) intracellular deposits identified by anti-human hyperphosphorylated tau protein antibodies. This novel non-transgenic, self-sustained model of neurodegeneration triggered by the association of two prevalent insults to the aging human brain (ischemia and hyperthermia) presents morphological features similar to those of Alzheimer's disease. This finding raises the possibility that febrile complications of acute brain injuries may similarly impair human cognitive function in the long run

116. Streit WJ (2002) Microglia and the response to brain injury. Ernst.Schering.Res.Found.Workshop11-24

117. Strohmeyer R, Ramirez M, Cole GJ, Mueller K, Rogers J (2002) Association of factor H of the alternative pathway of complement with agrin and complement receptor 3 in the Alzheimer's disease brain. J.Neuroimmunol. 131:135-146
     Abstract: Factor H, a regulatory protein of the alternative pathway of complement (APC), is present in amyloid-beta (Abeta) plaques in Alzheimer's disease (AD). Abeta plaques also contain significant amounts of heparan sulfate proteoglycans (HSPGs), such as agrin, as well as numerous activated Microglia expressing increased levels complement receptor 3 (CR3). Here, we show the colocalization of each of these molecules in the AD brain and the functional capacity for these molecules to bind to one another in vitro. We propose that CR3 receptors expressed by Microglia are used for ligand binding to factor H bound to HSPGs and Abeta in plaques in the AD brain

118. Takata K, Kitamura Y, Kakimura J, Shibagaki K, Taniguchi T, Gebicke-Haerter PJ, Smith MA, Perry G, Shimohama S (2002) Possible protective mechanisms of heme oxygenase-1 in the brain. Ann.N.Y.Acad.Sci. 977:501-506

119. Tan J, Town T, Mullan M (2002) CD40-CD40L interaction in Alzheimer's disease. Curr.Opin.Pharmacol. 2:445-451
     Abstract: Increasing evidence supports a role of the CD40 receptor-CD40 ligand (CD40-CD40L) interaction in the pathogenesis of Alzheimer's disease (AD). It has previously been shown that this dyad acts synergistically with the Alzheimer amyloid-beta peptide to promote Microglial activation. Reactive Microglia produce potentially neurotoxic substances such as tumor necrosis factor alpha and the reactive oxygen species nitric oxide, which can induce bystander neuronal injury at high levels. When a transgenic mouse model of AD is crossed with an animal deficient in CD40L, the resulting phenotype is deficient in the gliosis observed in a mouse model of AD in which CD40L is present. Additionally, these crossed animals have complete absence of AD-like neuronal Tau hyperphosphorylation, a marker of the preneuronal tangle pathology in AD patients. This suggests that the CD40-CD40L system is a critical enhancer of Microglial activation in an AD transgenic mouse model and that such activation is associated with an increase in a key indicator of neuronal stress. Conversely, the finding that reduced CD40-CD40L interaction is associated with reduced chronic microgliosis and Tau hyperphosphorylation supports the view that, in general, mechanisms that reduce microgliosis will be beneficial in AD

120. Tan J, Town T, Crawford F, Mori T, DelleDonne A, Crescentini R, Obregon D, Flavell RA, Mullan MJ (2002) Role of CD40 ligand in amyloidosis in transgenic Alzheimer's mice. Nat.Neurosci. 5:1288-1293
     Abstract: We have shown that interaction of CD40 with CD40L enables Microglial activation in response to amyloid-beta peptide (Abeta), which is associated with Alzheimer's disease (AD)-like neuronal tau hyperphosphorylation in vivo. Here we report that transgenic mice overproducing Abeta, but deficient in CD40L, showed decreased astrocytosis and microgliosis associated with diminished Abeta levels and beta-amyloid plaque load. Furthermore, in the PSAPP transgenic mouse model of AD, a depleting antibody against CD40L caused marked attenuation of Abeta/beta-amyloid pathology, which was associated with decreased amyloidogenic processing of amyloid precursor protein (APP) and increased circulating levels of Abeta. Conversely, in neuroblastoma cells overexpressing wild-type human APP, the CD40-CD40L interaction resulted in amyloidogenic APP processing. These findings suggest several possible mechanisms underlying mitigation of AD pathology in response to CD40L depletion, and validate the CD40-CD40L interaction as a target for therapeutic intervention in AD

121. Taylor DL, Diemel LT, Cuzner ML, Pocock JM (2002) Activation of group II metabotropic glutamate receptors underlies Microglial reactivity and neurotoxicity following stimulation with chromogranin A, a peptide up-regulated in Alzheimer's disease. J.Neurochem. 82:1179-1191
     Abstract: Regulation of Microglial reactivity and neurotoxicity is critical for neuroprotection in neurodegenerative diseases. Here we report that Microglia possess functional group II metabotropic glutamate receptors, expressing mRNA and receptor protein for mGlu2 and mGlu3, negatively coupled to adenylate cyclase. Two different agonists of these receptors were able to induce a neurotoxic Microglial phenotype which was attenuated by a specific antagonist. Chromogranin A, a secretory peptide expressed in amyloid plaques in Alzheimer's disease, activates Microglia to a reactive neurotoxic phenotype. Chromogranin A-induced Microglial activation and subsequent neurotoxicity may also involve an underlying stimulation of group II metabotropic glutamate receptors since their inhibition reduced chromogranin A-induced Microglial reactivity and neurotoxicity. These results show that selective inhibition of Microglial group II metabotropic glutamate receptors has a positive impact on neuronal survival, and may prove a therapeutic target in Alzheimer's disease

122. Ujiie M, Dickstein DL, Jefferies WA (2002) p97 as a biomarker for Alzheimer disease. Front Biosci. 7:e42-e47
     Abstract: The search is ongoing for a reliable serum biomarker for AD. The level of iron is elevated in the brain of Alzheimer's disease (AD) patients. Our studies have demonstrated that the level of the iron transport protein, p97, is increased in the serum of AD patients but not in various control groups. These results have recently been confirmed by another laboratory who extended our findings by demonstrating that p97 is not elevated in other neurodegenerative diseases. This qualifies p97 as a potentially powerful biomarker specific for AD. Although the relationship between increased level of iron and p97 in the AD brain is not well understood, our research supports the hypothesis that p97 over-expressed by senile plaque associated reactive Microglia is exocytosed and appears in blood. The relationship between elevated levels of serum p97 and AD, together with the possible future clinical application of p97 are considered in this report

123. Van Everbroeck B, Dewulf E, Pals P, Lubke U, Martin JJ, Cras P (2002) The role of cytokines, astrocytes, Microglia and apoptosis in Creutzfeldt-Jakob disease. Neurobiol.Aging 23:59-64
     Abstract: In order to investigate inflammation and apoptosis in Creutzfeldt-Jakob disease (CJD) patients, we analyzed astrocytes, Microglia and apoptotic neurons in brain and IL-1beta in cerebrospinal fluid (CSF). Our results showed increased numbers of astrocytes in CJD and increased numbers of Microglia and apoptotic neurons both in CJD and Alzheimer's disease (AD) as compared to controls. All these markers correlated (P < 0.001) with the severity of the neuropathological lesions. An increased IL-1beta concentration was found in AD and CJD CSF that correlated with the number of Microglia and which did not change in the disease course of CJD.In conclusion, apoptotic neurons in CJD correlates to the neuropathological lesions and are probably related to the presence of inflammatory cells and cytokines which are present during the whole CJD disease process

124. Walker DG, Lue LF, Beach TG (2002) Increased expression of the urokinase plasminogen-activator receptor in amyloid beta peptide-treated human brain Microglia and in AD brains. Brain Res. 926:69-79
     Abstract: The urokinase plasminogen-activator receptor (uPAR) is involved in many processes in inflammation including the migration of inflammatory-associated cells to sites of tissue damage. This receptor, also designated as CD87, is induced in response to a range of stimuli and is a marker of macrophage activation. Its role in inflammatory responses of Microglia in Alzheimer's disease (AD) has not been previously investigated. In this study we demonstrate that uPAR mRNA and protein expression is induced following incubation of human post-mortem brain-derived Microglia with fibrillar amyloid beta (Abeta) peptide. This response was stronger with Abeta peptide than with other tested pro-inflammatory agents. Induction of uPAR surface expression by Microglia was inhibited by the antioxidant N-acetyl-cysteine, indicating that this gene may be induced as a result of oxidative stress-related mechanisms. The significance of these findings to AD was investigated. UPAR protein levels were significantly increased in human brain tissues from the hippocampus, superior frontal gyrus and inferior temporal gyrus of AD cases compared with similar tissues from non-demented cases. Increased uPAR expression was not demonstrated in AD cerebellum. Finally, increased uPAR immunoreactivity was demonstrated in activated Microglia in AD brain samples using two different antibodies to uPAR. These results provide a connection between the induction of oxidative stress in AD and Microglial activation, and establish a possible involvement of uPAR in AD pathogenesis

125. Wierzba-Bobrowicz T, Gwiazda E, Kosno-Kruszewska E, Lewandowska E, Lechowicz W, Bertrand E, Szpak GM, Schmidt-Sidor B (2002) Morphological analysis of active Microglia--rod and ramified Microglia in human brains affected by some neurological diseases (SSPE, Alzheimer's disease and Wilson's disease). Folia Neuropathol. 40:125-131
     Abstract: The activation of Microglial cells in pathological conditions is manifested primarily by their proliferation, as well as by the occurrence of a new morphological form--rod Microglia. In the present study immunohistochemical identification of rod Microglial phenotype against ramified Microglia was performed on segments of 17 brains derived from 7 cases of encephalitis of viral aetiology (including 5 SSPE cases), 6 cases of Wilson's disease and 4 cases of Alzheimer's disease. Segments from frontal, temporal and occipital lobes, cerebellum and brainstem were subjected to histological, histochemical and immunohistochemical reactions. The presence of activated rod and ramified Microglia was observed in sections derived from all structures of the brains under study. Both morphological forms of activated Microglia reacted to antibodies: HLA II, CD68, HAM56 and lectin RCA-1. Expression of HLA II molecules was less intensive on the surface of Microglial rod cells. A positive reaction to PCNA antibody was mainly observed in rod/elongated/cylinder-shaped nuclei, which is a characteristic feature of rod Microglia. In the study material, the localisation of Microglial processes seemed to depend rather on the structural topography of the cell in the brain than on the nuclear shape of the activated Microglial cell. Our observations revealed a strong similarity between immunohistochemical phenotypes of both morphological forms of Microglia with the indication that rod Microglia is a first developmental form of activated Microglia

126. Wyss-Coray T, Yan F, Lin AH, Lambris JD, Alexander JJ, Quigg RJ, Masliah E (2002) Prominent neurodegeneration and increased plaque formation in complement-inhibited Alzheimer's mice. Proc.Natl.Acad.Sci.U.S.A 99:10837-10842
     Abstract: Abnormal accumulation of beta-amyloid (Abeta) in Alzheimer's disease (AD) is associated with prominent brain inflammation. Whereas earlier studies concluded that this inflammation is detrimental, more recent animal data suggest that at least some inflammatory processes may be beneficial and promote Abeta clearance. Consistent with these observations, overproduction of transforming growth factor (TGF)-beta1 resulted in a vigorous Microglial activation that was accompanied by at least a 50% reduction in Abeta accumulation in human amyloid precursor protein (hAPP) transgenic mice. In a search for inflammatory mediators associated with this reduced pathology, we found that brain levels of C3, the central component of complement and a key inflammatory protein activated in AD, were markedly higher in hAPP/TGF-beta1 mice than in hAPP mice. To assess the importance of complement in the pathogenesis of AD-like disease in mice, we inhibited C3 activation by expressing soluble complement receptor-related protein y (sCrry), a complement inhibitor, in the brains of hAPP mice. Abeta deposition was 2- to 3-fold higher in 1-year-old hAPP/sCrry mice than in age-matched hAPP mice and was accompanied by a prominent accumulation of degenerating neurons. These results indicate that complement activation products can protect against Abeta-induced neurotoxicity and may reduce the accumulation or promote the clearance of amyloid and degenerating neurons. These findings provide evidence for a role of complement and innate immune responses in AD-like disease in mice and support the concept that certain inflammatory defense mechanisms in the brain may be beneficial in neurodegenerative disease

127. Zatta P, Zambenedetti P, Stella MP, Licastro F (2002) Astrocytosis, microgliosis, metallothionein-I-II and amyloid expression in high cholesterol-fed rabbits. J.Alzheimers.Dis. 4:1-9
     Abstract: Cholesterol is considered a risk factor in vascular dementia as well as in Alzheimer's disease. Several biochemical, epidemiological and genetic aspects established a correlation between cholesterol concentration and Alzheimer's disease. Microglia activation, astrocytosis with metallothionein-I-II overexpression, amyloid beta intraneuronal accumulation and a rare formation of amyloid beta extracellular positive deposits were the major immunohistochemical features observed in the brain of high cholesterol-fed animals. The relevance on the cholesterol metabolism in Alzheimer's disease pathogenesis is also discussed

128. Allison AC, Cacabelos R, Lombardi VR, Alvarez XA, Vigo C (2001) Celastrol, a potent antioxidant and anti-inflammatory drug, as a possible treatment for Alzheimer's disease. Prog.Neuropsychopharmacol.Biol.Psychiatry 25:1341-1357
     Abstract: In the brains of patients with Alzheimer's disease (AD) signs of neuronal degeneration are accompanied by markers of Microglial activation, inflammation, and oxidant damage. The presence of nitrotyrosine in the cell bodies of neurons in AD suggests that peroxynitrite contributes to the pathogenesis of the disease. A drug with antioxidant and anti-inflammatory activity may prevent neuronal degeneration in AD. Celastrol, a plant-derived triterpene, has these effects. In low nanomolar concentrations celastrol was found to suppress the production by human monocytes and macrophages of the pro-inflammatory cytokines TNF-alpha and IL-1beta. Celastrol also decreased the induced expression of class II MHC molecules by Microglia. In macrophage lineage cells and endothelial cells celastrol decreased induced but not constitutive NO production. Celastrol suppressed adjuvant arthritis in the rat, demonstrating in vivo anti-inflammatory activity. Low doses of celastrol administered to rats significantly improved their performance in memory, learning and psychomotor activity tests. The potent antioxidant and anti-inflammatory activities of celastrol, and its effects on cognitive functions, suggest that the drug may be useful to treat neurodegenerative diseases accompanied by inflammation, such as AD

129. Anderson I, Adinolfi C, Doctrow S, Huffman K, Joy KA, Malfroy B, Soden P, Rupniak HT, Barnes JC (2001) Oxidative signalling and inflammatory pathways in Alzheimer's disease. Biochem.Soc.Symp.141-149
     Abstract: It is well established that inflammation and oxidative stress are key components of the pathology of Alzheimer's disease (AD), but how early in the pathological cascade these processes are involved or which specific molecular components are key, has not been fully elucidated. This paper describes the pharmacological approach to understand the molecular components of inflammation and oxidative stress on the activation of Microglial cells and neuronal cell viability. We have shown that activation of Microglia with the 42-amino-acid form of the beta-amyloid peptide (A beta 42) activates the production of cyclooxygenase-2, the inducible form of nitric oxide synthase and tumour necrosis factor-alpha and there appears to be little interactive feedback between these three mediators. Moreover, we explore the effects of a series of salen-manganese complexes, EUK-8, -134 and -189, which are known to possess both superoxide and catalase activity. These compounds are able to protect cells from insults produced by hydrogen peroxide or peroxynitrite. Moreover, EUK-134 was also able to limit the output of prostaglandin E2 from activated Microglial cells. The mechanisms underlying these effects are discussed. Together, these data support a pivotal role for oxidative stress and inflammation as key mediators of the pathological cascade in AD and provide some ideas about possible therapeutic targets

130. Apelt J, Schliebs R (2001) Beta-amyloid-induced glial expression of both pro- and anti-inflammatory cytokines in cerebral cortex of aged transgenic Tg2576 mice with Alzheimer plaque pathology. Brain Res. 894:21-30
     Abstract: To elucidate the mechanisms involved in beta-amyloid-mediated inflammation in Alzheimer's disease, transgenic Tg2576 mice containing as transgene the Swedish double mutation of human amyloid precursor protein 695, were examined for the expression pattern of various cytokines using double immunocytochemistry and laser scanning microscopy. Tg2576 mice studied at postnatal ages of 13, 16 and 19 months demonstrated an age-related accumulation of both senile and diffuse beta-amyloid plaques in neocortex and hippocampus. Reactive interleukin (IL)-1beta-immunoreactive astrocytes were found in close proximity to both fibrillary and diffuse beta-amyloid deposits detectable at very early stages of plaque development, while activated Microglia appeared in and around fibrillary beta-amyloid plaques only. Subpopulations of reactive astrocytes also demonstrated immunolabeling for transforming growth factor (TGF)-beta1, TGF-beta3, and IL-10, already detectable in 13-month-old transgenic mouse brain, while a few IL-6-immunoreactive astrocytes were observed only at later stages of plaque development. The early beta-amyloid-mediated upregulation of IL-1beta, TGF-beta, and IL-10 in surrounding reactive astrocytes indicates the induction of both pro- and anti-inflammatory mechanisms. The transgenic approach used in this study may thus provide a useful tool to further disclose the in vivo mechanisms by which pro- and anti-inflammatory cytokines interact and/or contribute to the progression of Alzheimer's disease

131. Bacskai BJ, Kajdasz ST, Christie RH, Carter C, Games D, Seubert P, Schenk D, Hyman BT (2001) Imaging of amyloid-beta deposits in brains of living mice permits direct observation of clearance of plaques with immunotherapy. Nat.Med. 7:369-372

132. Bamberger ME, Landreth GE (2001) Microglial interaction with beta-amyloid: implications for the pathogenesis of Alzheimer's disease. Microsc.Res.Tech. 54:59-70
     Abstract: The etiology of Alzheimer's disease (AD) involves a significant inflammatory component as evidenced by the presence of elevated levels of a diverse range of proinflammatory molecules in the AD brain. These inflammatory molecules are produced principally by activated Microglia, which are found to be clustered within and adjacent to the senile plaque. Moreover, long-term treatment of patients with non-steroidal anti-inflammatory drugs has been shown to reduce risk and incidence of AD and delay disease progression. The Microglia respond to beta-amyloid (Abeta) deposition in the brain through the interaction of fibrillar forms of amyloid with cell surface receptors, leading to the activation of intracellular signal transduction cascades. The activation of multiple independent signaling pathways ultimately leads to the induction of proinflammatory gene expression and production of reactive oxygen and nitrogen species. These Microglial inflammatory products act in concert to produce neuronal toxicity and death. Therapeutic approaches focused on inhibition of the Microglial-mediated local inflammatory response in the AD brain offer new opportunities to intervene in the disease

133. Bayer TA, Wirths O, Majtenyi K, Hartmann T, Multhaup G, Beyreuther K, Czech C (2001) Key factors in Alzheimer's disease: beta-amyloid precursor protein processing, metabolism and intraneuronal transport. Brain Pathol. 11:1-11
     Abstract: During the last years it has become evident that the beta-amyloid (Abeta) component of senile plaques may be the key molecule in the pathology of Alzheimer's disease (AD). The source and place of the neurotoxic action of Abeta, however, is still a matter of controversy. The precursor of the beta-amyloid peptide is the predominantly neuronal beta-amyloid precursor protein. We, and others, hypothesize that intraneuronal misregulation of APP leads to an accumulation of Abeta peptides in intracellular compartments. This accumulation impairs APP trafficking, which starts a cascade of pathological changes and causes the pyramidal neurons to degenerate. Enhanced Abeta secretion as a function of stressed neurons and remnants of degenerated neurons provide seeds for extracellular Abeta aggregates, which induce secondary degenerative events involving neighboring cells such as neurons, astroglia and macrophages/Microglia. Beta-amyloid precursor protein has a pivotal role in Alzheimer's disease

134. Benveniste EN, Nguyen VT, O'Keefe GM (2001) Immunological aspects of Microglia: relevance to Alzheimer's disease. Neurochem.Int. 39:381-391
     Abstract: Alzheimer's disease (AD) is a progressive dementing neurologic illness, and the most frequent cause of dementia in the elderly. Neuritic plaques are one of the main neuropathological findings in AD, and the major protein component is the beta-amyloid protein (A beta). Another striking feature of neuritic plaques is the presence of activated Microglia, cytokines, and complement components, suggestive of "inflammatory foci" within AD brain. In this review, we will examine the mechanisms by which Microglia become activated in AD, emphasizing the role in the A beta protein and proinflammatory cytokines. As well, pathways for suppression of Microglial activation by immunosuppressive cytokines will be described. Inflammation mediated by activated Microglia is an important component of AD pathophysiology, and strategies to control this response could provide new therapeutic approaches for the treatment of AD

135. Blasko I, Apochal A, Boeck G, Hartmann T, Grubeck-Loebenstein B, Ransmayr G (2001) Ibuprofen decreases cytokine-induced amyloid beta production in neuronal cells. Neurobiol.Dis. 8:1094-1101
     Abstract: Trying to decrease the production of Amyloid beta (Abeta) has been envisaged as a promising approach to prevent neurodegeneration in Alzheimer's disease (AD). A chronic inflammatory reaction with activated Microglia cells and astrocytes is a constant feature of AD. The participation of the immune system in the disease process is further documented in several retrospective clinical studies showing an inverse relationship between the prevalence of AD and nonsteroidal anti-inflammatory drug (NSAID) therapy. Previously, we demonstrated that the combination of the proinflammatory cytokines TNFalpha with IFNgamma induces the production of Abeta-42 and Abeta-40 in human neuronal cells. In the present study, the neuronal cell line Sk-n-sh was incubated for 12 h with the cyclooxygenase inhibitor ibuprofen and subsequently stimulated with the cytokines TNFalpha and IFNgamma. Ibuprofen treatment decreased the secretion of total Abeta in the conditioned media of cytokine stimulated cells by 50% and prevented the accumulation of Abeta-42 and Abeta-40 in detergent soluble cell extracts. Viability of neuronal cells measured by detection of apoptosis was neither influenced by ibuprofen nor by cytokine treatment. The reduction in the production of Abeta by ibuprofen was presumably due to a decreased production of betaAPP, which in contrast to the control proteins M2 pyruvate kinase, beta-tubulin and the cytokine inducible ICAM-1 was detected at low concentration in ibuprofen treated cells. The data demonstrate a possible mechanism how ibuprofen may decrease the risk and delay the onset of AD

136. Cagnin A, Brooks DJ, Kennedy AM, Gunn RN, Myers R, Turkheimer FE, Jones T, Banati RB (2001) In-vivo measurement of activated Microglia in dementia. Lancet 358:461-467
     Abstract: BACKGROUND: Activated Microglia have a key role in the brain's immune response to neuronal degeneration. The transition of Microglia from the normal resting state to the activated state is associated with an increased expression of receptors known as peripheral benzodiazepine binding sites, which are abundant on cells of mononuclear phagocyte lineage. We used brain imaging to study expression of these sites in healthy individuals and patients with Alzheimer's disease. METHODS: We studied 15 normal individuals (age 32-80 years), eight patients with Alzheimer's disease, and one patient with minimal cognitive impairment. Quantitative in-vivo measurements of glial activation were obtained with positron emission tomography (PET) and carbon-11-labelled (R)-PK11195, a specific ligand for the peripheral benzodiazepine binding site. FINDINGS: In normal individuals, regional [11C](R)-PK11195 binding did not significantly change with age, except in the thalamus, where an age-dependent increase was found. By contrast, patients with Alzheimer's disease showed significantly increased regional [11C](R)-PK11195 binding in the entorhinal, temporoparietal, and cingulate cortex. INTERPRETATION: In-vivo detection of increased [11C](R)-PK11195 binding in Alzheimer-type dementia, including mild and early forms, suggests that Microglial activation is an early event in the pathogenesis of the disease

137. Chung S, Lee J, Joe EH, Uhm DY (2001) Beta-amyloid peptide induces the expression of voltage dependent outward rectifying K+ channels in rat Microglia. Neurosci.Lett. 300:67-70
     Abstract: Upregulation of voltage-dependent outward rectifying K+ (Kv) channels has been reported in activated Microglia. Since beta-amyloid peptide (A beta) is known to activate Microglia, we tested whether the exposure of cultured rat Microglia to A beta fragment 25-35 (A beta 25-35) induced the Kv current. A beta 25-35 in 5-200 nM concentration range significantly increased Kv current density, while there was small change in inward rectifying K+ current density. The full length A beta peptide (A beta 1-42) also increased Kv current. However, the control peptide, A beta 35-25, did not induce Kv current. Most of the Kv current induced by A beta was specifically blocked by the presence of antisense deoxyoligonucleotides against Kv1.3, and Kv1.5. Thus, it is concluded that we have identified Kv1.3 and Kv1.5 as the channel types expressed in A beta-treated Microglia

138. Clapp-Lilly KL, Smith MA, Perry G, Duffy LK (2001) Melatonin reduces interleukin secretion in amyloid-beta stressed mouse brain slices. Chem.Biol.Interact. 134:101-107
     Abstract: Neurodegeneration in Alzheimer's disease (AD) is associated with many features of the immune system. For example, cytokines such as IL-6, synthesized by Microglia and astrocytes, are associated with senile plaques. To further study the role of cytokines in early stage AD neurodegeneration, an organotypic mouse brain slice culture system with Microglia and astrocytes was developed. Amyloid-beta(Abeta1-40) induced the secretion of both IL-1beta and IL-6. Melatonin, an antioxidant and pineal hormone, reduced interleukin secretion in a concentration dependent manner. We also observed that melatonin, alone, had no effect on IL-1beta secretion but at a concentration of 500 microM induced the secretion of IL-6. This organotypic slice system can be used to study the early role of immune system molecules on neurodegeneration

139. Combs CK, Karlo JC, Kao SC, Landreth GE (2001) beta-Amyloid stimulation of Microglia and monocytes results in TNFalpha-dependent expression of inducible nitric oxide synthase and neuronal apoptosis. J.Neurosci. 21:1179-1188
     Abstract: Reactive Microglia associated with the beta-amyloid plaques in Alzheimer's disease (AD) brains initiate a sequence of inflammatory events integral to the disease process. We have observed that fibrillar beta-amyloid peptides activate a tyrosine kinase-based signaling response in primary mouse Microglia and the human monocytic cell line, THP-1, resulting in production of neurotoxic secretory products, proinflammatory cytokines, and reactive oxygen species. We report that most of the amyloid-induced tyrosine kinase activity was stimulated after activation of Src family members such as Lyn. However, transduction of the signaling response required for increased production of the cytokines TNFalpha and IL1-beta was mediated by the nonreceptor tyrosine kinase, Syk. Additionally, beta-amyloid stimulated an NFkappaB-dependent pathway in parallel that was required for cytokine production. Importantly, TNFalpha generated by the monocytes and Microglia was responsible for the majority of the neuorotoxic activity secreted by these cells after beta-amyloid stimulation but must act in concert with other factors elaborated by Microglia to elicit neuronal death. Moreover, we observed that the neuronal loss was apoptotic in nature and involved increased neuronal expression of inducible nitric oxide synthase and subsequent peroxynitrite production. Selective inhibitors of inducible nitric oxide synthase effectively protected cells from toxicity associated with the Microglial and monocytic secretory products. This study demonstrates a functional linkage between beta-amyloid-dependent activation of Microglia and several characteristic markers of neuronal death occurring in Alzheimer's disease brains

140. Dandrea MR, Reiser PA, Gumula NA, Hertzog BM, Andrade-Gordon P (2001) Application of triple immunohistochemistry to characterize amyloid plaque-associated inflammation in brains with Alzheimer's disease. Biotech.Histochem. 76:97-106
     Abstract: Inflammation, characterized by the presence of activated Microglia and reactive astrocytes (gliosis), has been described in Alzheimer's disease (AD). We used our routine single immunohistochemical (IHC) labeling protocol to label amyloid plaques, an AD neuropathological hallmark, activated Microglia, and reactive astrocytes in serial sections of AD hippocampus and entorhinal cortex of brain. Although most amyloid plaques were associated with inflammation throughout the serial sections, the extent of Microglial and astrocytic activation varied among the amyloid plaques. We also observed a population of amyloid plaques that did not appear to coincide with immunolabeled Microglia and astrocytes in serial sections, leading us to speculate that some amyloid plaques are not associated with inflammation. Because serial sectioning limited our ability to confirm these findings, we developed a triple IHC protocol to investigate the association of activated Microglia and reactive astrocytes simultaneously with amyloid plaques in sections of AD brain entorhinal cortex and hippocampus. Unlike the potential errors of extrapolating descriptive information from routine IHC or histochemical staining methods on sectioned tissues, triple IHC allowed direct characterization of three differently colored antigens in situ. The success of the protocol depended on selection of distinguishable color schemes and resolution of other critical technical elements including the compatibility of the reagents and the sensitivity and sequence of the detection systems. The results of the triple IHC protocol clarified the spatial relation of Microglia and astrocytes with amyloid plaques and provoked novel interpretations about the roles of inflammation in AD brain tissues. We categorized three distinct populations of amyloid plaques related to of inflammation: 1) Abeta42 immunoreactive (a marker of amyloid plaques) amyloid plaques without activated Microglia or reactive astrocytes, 2) Abeta42-positive amyloid plaques with HLA-DR (a marker of Microglia)-positive Microglia and no astrocytes, 3) Abeta42-positive amyloid plaques among HLA-DR and GFAP (a marker of astrocytes) immunoreactive astrocytes. Most amyloid plaques had varying degrees of activated Microglia and reactive astrocytes. Some of the amyloid plaques were not associated with inflammation while others were associated only with activated Microglia. These findings suggest that amyloid plaques without associated inflammation may represent recently formed plaques and that the presence of amyloid plaques in AD brains may activate Microglia prior to gliosis. Furthermore, the shape of the amyloid plaques may be altered subsequently from its typical spherical to an aspherical shape by the inflammatory cells

141. De Groot CJ, Hulshof S, Hoozemans JJ, Veerhuis R (2001) Establishment of Microglial cell cultures derived from postmortem human adult brain tissue: immunophenotypical and functional characterization. Microsc.Res.Tech. 54:34-39
     Abstract: Cell cultures have become an integral part of the daily routine in most biological research laboratories. Because they are very dynamic and highly accessible, cell cultures permit direct experimental manipulations where cause-effect relations can be more definitely assayed. We have developed cultures of Microglial cells from rapid autopsies (range 3-10 hours) of nondemented elderly patients and Alzheimer's disease patients. Cultures were derived from the subcortical white matter, corpus callosum, and frontal, temporal, and occipital cortex. The adherent Microglial cells were immunoreactive for CD68, CD45, CD11c, and major histocompatibility complex (MHC) class II markers, and were not immunoreactive for astrocyte or oligodendrocyte markers. In addition, some functional characteristics of the isolated Microglial cells were also studied. Upon stimulation with lipopolysaccharide (LPS), Microglial cells secreted pro- and antiinflammatory mediators, i.e., interleukin- (IL)-6, prostaglandin E2 (PGE2), and IL-10, indicating the functional capacity of cultured Microglia

142. Ferencik M, Novak M, Rovensky J, Rybar I (2001) Alzheimer's disease, inflammation and non-steroidal anti-inflammatory drugs. Bratisl.Lek.Listy 102:123-132
     Abstract: Alzheimer's disease (AD) is a degenerative disease of the brain, which causes dementia. The disease is characterised by three main pathogenic factors: senile plaques, neurofibrillary tangles and inflammation. the participation of the local inflammatory reaction is confirmed especially by the results of studies dealing with activated Microglia, reactive astrocytes, complement system, cytokines, reactive mediators of oxygen and nitrogen (free radicals), all of which participate significantly in inflammatory processes. These inflammatory markers are locally produced by brain cells, and occur in close proximity of beta-amyloid and tau protein deposits. Moreover, some epidemiologic and pilot clinical studies have proven that long-term administration of anti-inflammatory drugs have a protective effect on the onset of AD. Out of them, non-steroidal anti-inflammatory drugs (NSAIDs) are most extensively investigated medicaments. Despite some contradictory findings, the prevalent majority of these studies prove that long-term application of anti-inflammatory treatment can delay the onset, or at least slow down the progression of AD, namely in people between 65 and 75 years of age. The most appropriate prophylactic effect seems to be achieved by specific inhibitors of cyclooxygenase-2 (COX-2), namely celecoxib and rofecoxib. These preparations protect the gastrointestinal tract better than classical NSAIDs which inhibit both isoenzymes--COX-1 and COX-2. COX-2 is expressed in higher concentrations in the degenerating cells of the brain and this excessive expression can be decreased by selective inhibitors. The latter decrease also the excessive activation of some transcription factors (PPARgama and the nuclear factor kapa-B), which are responsible for the initiation of transcription of a number of pro-inflammatory genes. The selective inhibitors COX-2 can thereby have an anti-inflammatory effect operating on several levels. (Tab. 1, Fig. 1, Ref. 75.)

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

144. Glabe C (2001) Intracellular mechanisms of amyloid accumulation and pathogenesis in Alzheimer's disease. J.Mol.Neurosci. 17:137-145
     Abstract: Cell-culture studies have revealed some of the fundamental features of the interaction of amyloid Abeta with cells and the mechanism of amyloid accumulation and pathogenesis in vitro. A(beta)1-42, the longer isoform of amyloid that is preferentially concentrated in senile plaque (SP) amyloid deposits in Alzheimer's disease (AD), is resistant to degradation and accumulates as insoluble aggregates in late endosomes or lysosomes. Once these aggregates have nucleated inside the cell, they grow by the addition of aberrantly folded APP and amyloidgenic fragments of APP, that would otherwise be degraded, onto the amyloid lattice in a fashion analogous to prion replication. This accumulation of heterogeneous aggregated APP fragments and Abeta appears to mimic the pathophysiologyof dystrophic neurites, where the same spectrum of components has been identified by immunohistochemistry. In the brain, this residue appears to be released into the extracellular space, possibly by a partially apoptotic mechanism that is restricted to the distal compartments of the neuron. Ultimately, this insoluble residue may be further digested to the protease-resistant A(beta)n-42 core, perhaps by Microglia, where it accumulates as senile plaques. Thus, the dystrophic neurites are likely to be the source of the immediate precursors of amyloid in the senile plaques. This is the opposite of the commonly held view that extracellular accumulation of amyloid induces dystrophic neurites. Many of the key pathological events of AD may also be directly related to the intracellular accumulation of this insoluble amyloid. The aggregated, intracellular amyloid induces the production of reactive oxygen species (ROS) and lipid peroxidation products and ultimately results in the leakage of the lysosomal membrane. The breakdown of the lysosomal membrane may be a key pathogenic event, leading to the release of heparan sulfate and lysosomal hydrolases into the cytosol. Together, these observations provide the novel view that amyloid deposits and some of the early events of amyloid pathogenesis initiate randomly within single cells in AD. This pathogenic mechanism can explain some of the more enigmatic features of Alzheimer's pathogenesis, like the focal nature of amyloid plaques, the relationship between amyloid, dystrophic neurites and neurofibrillary-tangle pathology, and the miscompartmentalization of extracellular and cytosolic components observed in AD brain

145. Gyure KA, Durham R, Stewart WF, Smialek JE, Troncoso JC (2001) Intraneuronal abeta-amyloid precedes development of amyloid plaques in Down syndrome. Arch.Pathol.Lab Med. 125:489-492
     Abstract: CONTEXT: Down syndrome patients who live to middle age invariably develop the neuropathologic features of Alzheimer disease, providing a unique situation in which to study the early and sequential development of these changes. OBJECTIVE: To study the development of amyloid deposits, senile plaques, astrocytic and Microglial reactions, and neurofibrillary tangles in the brains of young individuals (<30 years of age) with Down syndrome. METHODS: Histologic and immunocytochemical study of a series of autopsy brains (n = 14, from subjects aged 11 months to 56 years, with 9 subjects <30 years) examined at the Office of the Chief Medical Examiner of the State of Maryland and The Johns Hopkins Hospital. RESULTS: The principal observations included the presence of intraneuronal Abeta immunostaining in the hippocampus and cerebral cortex of very young Down syndrome patients (preceding the extracellular deposition of Abeta) and the formation of senile plaques and neurofibrillary tangles. CONCLUSIONS: We propose the following sequence of events in the development of neuropathologic changes of Alzheimer disease in Down syndrome: (1) intracellular accumulation of Abeta in neurons and astrocytes, (2) deposition of extracellular Abeta and formation of diffuse plaques, and (3) development of neuritic plaques and neurofibrillary tangles with activation of Microglial cells

146. Hasegawa H, Nakai M, Tanimukai S, Taniguchi T, Terashima A, Kawamata T, Fukunaga K, Miyamoto E, Misaki K, Mukai H, Tanaka C (2001) Microglial signaling by amyloid beta protein through mitogen-activated protein kinase mediating phosphorylation of MARCKS. Neuroreport 12:2567-2571
     Abstract: Myristoylated alanine-rich C kinase substrate (MARCKS), an acidic protein associated with cell motility and phagocytosis, is activated upon phosphorylation by protein kinase C (PKC) and proline-directed protein kinases. In Alzheimer disease (AD), activated Microglia expressing MARCKS migrates around senile plaques. We reported that amyloid beta protein (A beta), a major component of senile plaques, activated MARCKS through a tyrosine kinase and PKC-delta. We have now identified another A beta signaling pathway through a mitogen-activated protein kinase (MAPK) involved in the phosphorylation of MARCKS and analysed cross-talk between PKC and MAPK pathways in primary cultured rat Microglia. A selective inhibitor for MAPK kinase, PD098059, significantly inhibited the phosphorylation of MARCKS induced by A beta. Extracellulary regulated kinases, the activities of which were induced by A beta, directly phosphorylated a recombinant MARCKS in vitro. The MAPK pathway was sensitive to wortmannin, but not to a PKC inhibitor or to tyrosine kinase inhibitors. The activation of PKC by A beta was not sensitive to wortmannin. Our findings suggest involvement of the MAPK pathway through phosphoinositol 3-kinase in the phosphorylation of MARCKS in rat cultured Microglia, an event may be associated with mechanisms activating Microglia in AD

147. Hass S, Weidemann A, Utermann G, Baier G (2001) Intracellular apolipoprotein E affects Amyloid Precursor Protein processing and amyloid Abeta production in COS-1 cells. Mol.Genet.Genomics 265:791-800
     Abstract: The apoE gene has been identified as a major susceptibility locus for late-onset Alzheimer's disease (LOAD). The epsilon4 allele greatly reduces age of onset of LOAD as compared to the wild-type 3 allele. The molecular mechanism(s) underlying the association has not yet been fully elucidated. The apoE protein has been shown to physically interact with the Abeta region of the Amyloid Precursor Protein (APP), but also with the ectodomain of the APP holoprotein itself. In this study we have used apoE fusion proteins containing either the ER retention sequence KDEL or trans-Golgi network (TGN) signal sequence in order to define potential apoE-mediated alterations in APP protein processing. Co-expression and pulse-chase experiments showed that a functional apoE:APP interaction occurs intracellularly which directly affects maturation and subsequently the secretion kinetics of APP. In addition, an epsilon4 allele-specific induction of Abeta production has been demonstrated. apoE3 resulted in increased Abeta production only when targeted to the ER, as observed in cells transfected with an apoE3KDEL fusion protein as well as following treatment with brefeldin A. The findings suggest that in cells that express both apoE and APP, such as astrocytes and Microglia, a functional apoE:APP interaction may occur which modulates APP processing and Abeta production

148. Head E, Azizeh BY, Lott IT, Tenner AJ, Cotman CW, Cribbs DH (2001) Complement association with neurons and beta-amyloid deposition in the brains of aged individuals with Down Syndrome. Neurobiol.Dis. 8:252-265
     Abstract: To study the link between beta-amyloid (Abeta) and neuroinflammation, we examined the levels of complement as a function of age and extent of Abeta deposition in Down Syndrome (DS) brain. C1q, the first component of the complement cascade, was visualized using immunohistochemistry in the frontal, entorhinal cortex, and hippocampus of 12 DS ranging from 31 to 69 years of age. C1q was consistently associated with thioflavine-S positive Abeta plaques in DS brain and increased with more extensive age-dependent Abeta deposition. In contrast, little or no C1q labeling was associated with diffuse or thioflavine-S negative Abeta deposits. Neurons in the hippocampus and entorhinal cortex, but less frequently in frontal cortex, were C1q positive in DS cases with sufficient neuropathology to have a diagnosis of Alzheimer's disease. C1q-positive neurons were associated with activated Microglia. These results provide evidence for Abeta-mediated inflammatory factors contributing to the rapid accumulation of neuropathology in DS brain

149. Head E, Garzon-Rodriguez W, Johnson JK, Lott IT, Cotman CW, Glabe C (2001) Oxidation of Abeta and plaque biogenesis in Alzheimer's disease and Down syndrome. Neurobiol.Dis. 8:792-806
     Abstract: The processes involved with beta-amyloid (Abeta) degradation and clearance in human brain are not well understood. We hypothesized that the distribution of oxidatively modified Abeta, as determined by an affinity-purified antibody in the entorhinal and frontal cortices of Alzheimer's disease (AD), Down syndrome (DS), nondemented elderly control cases, and canine brain, would provide insight into the mechanisms of Abeta accumulation. Based upon plaque counts, oxidized Abeta was present within 46-48% of diffuse and primitive plaques and 98% of cored plaques. Dense punctate deposits of oxidized Abeta were distributed throughout the neuropil in AD and DS brains but were also present within controls with mild neuropathology and isolated cognitive impairments. Confocal studies indicate that punctate oxidized Abeta deposits were within activated Microglia. Oxidatively modified Abeta may reflect the efforts of Microglial cells to take up and degrade Abeta. Oxidative modification of Abeta may be an early event in Abeta pathogenesis and may be important for plaque biogenesis

150. Heneka MT, Wiesinger H, Dumitrescu-Ozimek L, Riederer P, Feinstein DL, Klockgether T (2001) Neuronal and glial coexpression of argininosuccinate synthetase and inducible nitric oxide synthase in Alzheimer disease. J.Neuropathol.Exp.Neurol. 60:906-916
     Abstract: The enzyme argininosuccinate synthetase (ASS) is the rate limiting enzyme in the metabolic pathway leading from L-citrulline to L-arginine, the physiological substrate of all isoforms of nitric oxide synthases (NOS). ASS and inducible NOS (iNOS) expression in neurons and glia was investigated by immunohistochemistry in brains of Alzheimer disease (AD) patients and nondemented, age-matched controls. In 3 areas examined (hippocampus, frontal, and entorhinal cortex), a marked increase in neuronal ASS and iNOS expression was observed in AD brains. GFAP-positive astrocytes expressing ASS were not increased in AD brains versus controls, whereas the number of iNOS expressing GFAP-positive astrocytes was significantly higher in AD brains. Density measurements revealed that ASS expression levels were significantly higher in glial cells of AD brains. Colocalization of ASS and iNOS immunoreactivity was detectable in neurons and glia. Occasionally, both ASS-and iNOS expression was detectable in CD 68-positive activated Microglia cells in close proximity to senile plaques. These results suggest that neurons and astrocytes express ASS in human brain constitutively, whereas neuronal and glial ASS expression increases parallel to iNOS expression in AD. Because an adequate supply of L-arginine is indispensable for prolonged NO generation, coinduction of ASS enables cells to sustain NO generation during AD by replenishing necessary supply of L-arginine

151. Hoozemans JJ, Rozemuller AJ, Janssen I, De Groot CJ, Veerhuis R, Eikelenboom P (2001) Cyclooxygenase expression in Microglia and neurons in Alzheimer's disease and control brain. Acta Neuropathol.(Berl) 101:2-8
     Abstract: Epidemiological studies suggest that non-steroidal anti-inflammatory drugs (NSAIDs) lower the risk of developing Alzheimer's disease (AD). Most NSAIDs act upon local inflammatory events by inhibiting the expression or activation of cylooxygenase (COX). In the present study the expression of COX-1 and COX-2 in AD and non-demented control temporal and frontal cortex was investigated using immunohistochemistry. COX-1 expression was detected in Microglial cells, while COX-2 expression was found in neuronal cells. In AD brains, COX-1-positive Microglial cells were primarily associated with amyloid beta plaques, while the number of COX-2-positive neurons was increased compared to that in control brains. No COX expression was detected in astrocytes. In vitro, primary human Microglial and astrocyte cultures, and human neuroblastoma cells (SK-N-SH) were found to secrete prostaglandin E2 (PGE2), especially when stimulated. PGE2 synthesis by astrocytes and SK-N-SH cells was stimulated by interleukin-1beta. Microglial cell PGE2 synthesis was stimulated by lipopolysaccharide only. Although astrocytes are used in studies in vitro to investigate the role of COX in AD, there are no indications that these cells express COX-1 or COX-2 in vivo. The different distribution patterns of COX-1 and COX-2 in AD could implicate that these enzymes are involved in different cellular processes in the pathogenesis of AD

152. Hoozemans JJ, Rozemuller AJ, Veerhuis R, Eikelenboom P (2001) Immunological aspects of Alzheimer's disease: therapeutic implications. BioDrugs. 15:325-337
     Abstract: Alzheimer's disease (AD) is a chronic neurodegenerative disease causing progressive impairment of memory and cognitive function. The amyloid cascade hypothesis suggests that mismetabolism of the beta-amyloid (A beta) precursor protein (APP) followed by subsequent formation of non-fibrillar and fibrillar A beta deposits leads to glial activation and eventually to neurotoxicity, causing cognitive impairment. Several lines of evidence indicate that an inflammatory process contributes to the pathology of AD. First, inflammatory proteins have been identified as being associated with neuritic plaques and in glial cells surrounding these plaques. Second, certain polymorphisms of acute-phase proteins and cytokines associated with AD plaques increase the risk or predispose for earlier onset of developing AD. Third, epidemiological studies indicate that anti-inflammatory drugs can retard the development of AD. Several steps in the pathological cascade of AD have been identified as possible targets for actions of nonsteroidal anti-inflammatory drugs. For instance, Microglia are considered a target because this cell type is closely involved in AD pathology through secretion of neurotoxic substances and by modulating a positive feedback loop of the inflammatory mechanism that may be involved in the pathological cascade in AD. On the basis of studies in APP transgenic mice, immunisation with A beta was recently suggested as a novel immunological approach for the treatment of AD. Immunisation elicits A beta-specific antibodies that could affect several early steps of the amyloid-driven cascade. Antibodies could prevent A beta from aggregating into fibrils and accelerate clearance of A beta by stimulating its removal by Microglial cells. This review outlines the pathological and genetic evidence that an inflammatory mechanism is involved in AD and the therapeutic approaches based on inhibition or mediation of inflammation

153. Husemann J, Silverstein SC (2001) Expression of scavenger receptor class B, type I, by astrocytes and vascular smooth muscle cells in normal adult mouse and human brain and in Alzheimer's disease brain. Am.J.Pathol. 158:825-832
     Abstract: In Alzheimer's disease (AD), fibrillar beta-amyloid protein (fAbeta) accumulates in the walls of cerebral vessels associated with vascular smooth muscle cells (SMCs), endothelium, and pericytes, and with Microglia and astrocytes in plaques in the brain parenchyma. Scavenger receptor class A (SR-A) and class B, type I (SR-BI) mediate binding and ingestion of fAbeta by cultured human fetal Microglia, Microglia from newborn mice, and by cultured SMCs. Our findings that SR-BI participates in the adhesion of cultured Microglia from newborn SR-A knock-out mice to fAbeta-coated surfaces, and that Microglia secrete reactive oxygen species when they adhere to these surfaces prompted us to explore expression of SR-BI in vivo. We report here that astrocytes and SMCs in normal adult mouse and human brains and in AD brains express SR-BI. In contrast, Microglia in normal adult mouse and human brains and in AD brains do not express SR-BI. These findings indicate that SR-BI may mediate interactions between astrocytes or SMCs and fAbeta, but not of Microglia and fAbeta, in AD, and that expression of SR-BI by rodent Microglia is developmentally regulated. They suggest that SR-BI expression also is developmentally regulated in human Microglia

154. Husemann J, Loike JD, Kodama T, Silverstein SC (2001) Scavenger receptor class B type I (SR-BI) mediates adhesion of neonatal murine Microglia to fibrillar beta-amyloid. J.Neuroimmunol. 114:142-150
     Abstract: Class A scavenger receptors (SR-A) mediate Microglial interaction with fibrillar beta-amyloid (fAbeta). We report here that neonatal Microglia from SR-A knockout mice (SR-A-/-) adhere to surface-bound fAbeta, and produce reactive oxygen species (ROS) as efficiently as wildtype Microglia; that both wildtype and SR-A-/- Microglia express SR-BI; that antibodies against SR-BI do not affect adhesion or ROS production by wildtype Microglia, but inhibit adhesion and ROS production of SR-A-/- Microglia to immobilized fAbeta by approximately 40%. Adhesion to fAbeta-coated surfaces, and uptake of fAbeta by both wildtype and SR-A-/- Microglia was almost completely inhibited by incubation with fucoidan. Thus SR-BI and SR-A mediate similar effector functions in neonatal Microglia, which suggests that SR-BI plays as important a role as SR-A, and can maintain the wildtype phenotype in SR-A-/- Microglia

155. Imamura K, Sawada M, Ozaki N, Naito H, Iwata N, Ishihara R, Takeuchi T, Shibayama H (2001) Activation mechanism of brain Microglia in patients with diffuse neurofibrillary tangles with calcification: a comparison with Alzheimer disease. Alzheimer Dis.Assoc.Disord. 15:45-50
     Abstract: Diffuse neurofibrillary tangles with calcification (DNTC) is an atypical dementia and is characterized pathologically by diffuse neurofibrillary tangles (NFTs) without senile plaques (SPs). In this study, we investigated the distribution of human leukocyte antigen (HLA)-DR-positive activated Microglia in postmortem brain tissue of six patients with DNTC and six patients with Alzheimer disease (AD). HLA-DR-positive activated Microglia were observed to associate with SPs in AD. In the DNTC brain, which lacks SPs, HLA-DR-positive Microglia were mainly accumulated around weakly tau-positive NFTs, which were also positive for anti-amyloid-P and anti-C3d antibodies. The results of this study suggest that the complement pathway is also activated in the DNTC brain and that immune and inflammatory responses, including Microglia activation, may occur around extracellular NFTs in DNTC patients

156. Jellinger KA, Stadelmann C (2001) Problems of cell death in neurodegeneration and Alzheimer's Disease. J.Alzheimers.Dis. 3:31-40
     Abstract: Progressive cell loss in specific neuronal populations is a pathological hallmark of neurodegenerative diseases, but its mechanisms remain unresolved. Apoptosis or alternative pathways of neuronal death have been discussed in Alzheimer disease (AD) and other disorders. However, DNA fragmentation in human brain as a sign of neuronal injury is too frequent to account for the continuous loss in these slowly progressive diseases. In autopsy cases of AD, Parkinson's disease (PD), related disorders, and age-matched controls, DNA fragmentation using the TUNEL method and an array of apoptosis-related proteins (ARP), proto-oncogenes, and activated caspase 3, the key enzyme of late-stage apoptosis, were examined. In AD, a considerable number of hippocampal neurons and glial cells showed DNA fragmentation with a 3- to 6-fold increase related to amyloid deposits and neurofibrillary tangles, but only one in 2.600 to 5.650 neurons displayed apoptotic morphology and cytoplasmic immunoreactivity for activated caspase~3, whereas no neurons were labeled in age-matched controls. Caspase~3 immunoreactivity was seen in granules of cells with granulovacuolar degeneration, in around 25% In progressive supranuclear palsy, only single neurons but oligodendrocytes in brainstem, around 25% TUNEL-positive and expressed both ARPs and activated caspase 3. In PD, dementia with Lewy bodies, and multisystem atrophy (MSA), TUNEL-positivity and expression of ARPs or activated caspase~3 were only seen in Microglia and oligodendrocytes with cytoplasmic inclusions in MSA, but not in neurons. These data provide evidence for extremely rare apoptotic neuronal death in AD and PSP compatible with the progression of neuronal degeneration in these chronic diseases. Apoptosis mainly involves reactive Microglia and oligodendroglia, the latter occasionally involved by deposits of insoluble fibrillary proteins, while alternative mechanisms of neuronal death may occur. Susceptible cell populations in a proapoptotic environment, particularly in AD, show increased vulnerability towards metabolic or other noxious factors, with autophagy as a possible protective mechanism in early stages of programmed cell death. The intracellular cascade leading to cell death still awaits elucidation

157. Johnson S (2001) Gradual micronutrient accumulation and depletion in Alzheimer's disease. Med.Hypotheses 56:595-597
     Abstract: Cadmium is a carcinogen that accumulates relentlessly with age, reaching high levels in the liver and kidneys. It is known to hyperactivate the Kupffer cells (hepatic macrophages). On the other hand, the risk of developing Alzheimer's disease increases considerably with age and it involves neuronal damage by hyperactive Microglia (brain macrophages). Moreover, many of the metals that accumulate in the liver and kidneys, also accumulate in the brain (Fe, Cu, Zn, Mn, etc.). Therefore, it is possible that Cd also hyperactivates the Microglia, playing a role in Alzheimer's disease (AD).Fe also accumulates in the brain as we age and catalyzes super oxide (O2-) formation, which reacts with nitric oxide (NO) to form the very harmful peroxynitrite (ONOO-)

158. Jones RW (2001) Inflammation and Alzheimer's disease. Lancet 358:436-437

159. Kang J, Park EJ, Jou I, Kim JH, Joe EH (2001) Reactive oxygen species mediate A beta(25-35)-induced activation of BV-2 Microglia. Neuroreport 12:1449-1452
     Abstract: Microglial activation induced by beta-amyloid (A beta) is an important cellular response in the pathogenesis of Alzheimer's disease (AD). In this study, we show that reactive oxygen species (ROS) play a role as signaling molecules for the activation of NF-kappaB and induction of IL-1beta mRNA expression in A beta(25-35)-treated murine Microglia BV-2 cells. ROS scavengers such catalase and superoxide dismutase (SOD) mimetics obviously reduced activation of NF-kappaB and the elevated level of IL-1beta transcripts induced by A beta(25-35). In addition, the A beta(25-35)-induced NF-kappaB activation and IL-1beta expression were suppressed by blockers of the ROS generating enzymes such as NADPH oxidase, cyclooxygenase, and lipoxygenase. These data suggest that ROS mediate A beta-induced Microglial activation

160. Krause KH, Clark RA (2001) Geneva Biology of Ageing Workshop 2000: phagocytes, inflammation, and ageing. Exp.Gerontol. 36:373-381

161. Landreth GE, Heneka MT (2001) Anti-inflammatory actions of peroxisome proliferator-activated receptor gamma agonists in Alzheimer's disease. Neurobiol.Aging 22:937-944
     Abstract: The role of inflammatory processes in the brains of Alzheimer's Disease (AD) patients has recently attracted considerable interest. Indeed, the only demonstrated effective therapy for AD patients is long-term treatment with non-steroidal anti-inflammatory drugs (NSAIDs). The mechanistic basis of the efficacy of NSAIDs in AD remains unclear. However, the recent recognition that NSAIDs can bind to and activate the nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma), has offered an explanation for the action of these drugs in AD. PPARgamma activation leads to the inhibition of Microglial activation and the expression of a broad range of proinflammatory molecules. The newly appreciated anti-inflammatory actions of PPARgamma agonists may allow novel therapies for AD and other CNS indications with an inflammatory component

162. Le TV, Crook R, Hardy J, Dickson DW (2001) Cotton wool plaques in non-familial late-onset Alzheimer disease. J.Neuropathol.Exp.Neurol. 60:1051-1061
     Abstract: Cotton wool plaques (CWP) are large, ball-like plaques lacking dense amyloid cores that displace adjacent structures. They were first described in a Finnish kindred with early-onset Alzheimer disease (AD) with spastic paraparesis due to a presenilin-1 delta9 mutation. We describe a case of sporadic late-onset AD with numerous neocortical CWP as well as severe amyloid angiopathy and marked leukoencephalopathy, compared with 16 cases of late-onset AD with similar degrees of amyloid angiopathy and leukoencephalopathy. The cases were studied with histologic methods and with single and double immunostaining for beta-amyloid (Abeta), paired helical filaments-tau (PHF-tau), neurofilament (NF), glial fibrillary acidic protein (GFAP), HLA-DR, and amyloid precursor protein (APP). We found that CWP were well-circumscribed amyloid deposits infiltrated by ramified Microglia and surrounded by dystrophic neurites that were immunopositive for APP, but only weakly for NF and PHF-tau. Abeta1-12 was diffuse throughout the CWP, while Abeta37-42 was peripherally located and Abeta20-40 more centrally located. Two of the 16 late-onset AD cases also had CWP, but they were also admixed with diffuse plaques and plaques with dense amyloid cores. Pyramidal tract degeneration was not a consistent finding or a prominent feature in any case. The results suggest that CWP are not specific for early-onset familial AD with spastic paraparesis

163. Le Y, Gong W, Tiffany HL, Tumanov A, Nedospasov S, Shen W, Dunlop NM, Gao JL, Murphy PM, Oppenheim JJ, Wang JM (2001) Amyloid (beta)42 activates a G-protein-coupled chemoattractant receptor, FPR-like-1. J.Neurosci. 21:RC123
     Abstract: Amyloid beta (Abeta) is a major contributor to the pathogenesis of Alzheimer's disease (AD). Although Abeta has been reported to be directly neurotoxic, it also causes indirect neuronal damage by activating mononuclear phagocytes (Microglia) that accumulate in and around senile plaques. In this study, we show that the 42 amino acid form of beta amyloid peptide, Abeta(42), is a chemotactic agonist for a seven-transmembrane, G-protein-coupled receptor named FPR-Like-1 (FPRL1), which is expressed on human mononuclear phagocytes. Moreover, FPRL1 is expressed at high levels by inflammatory cells infiltrating senile plaques in brain tissues from AD patients. Thus, FPRL1 may mediate inflammation seen in AD and is a potential target for developing therapeutic agents

164. Lim GP, Chu T, Yang F, Beech W, Frautschy SA, Cole GM (2001) The curry spice curcumin reduces oxidative damage and amyloid pathology in an Alzheimer transgenic mouse. J.Neurosci. 21:8370-8377
     Abstract: Inflammation in Alzheimer's disease (AD) patients is characterized by increased cytokines and activated Microglia. Epidemiological studies suggest reduced AD risk associates with long-term use of nonsteroidal anti-inflammatory drugs (NSAIDs). Whereas chronic ibuprofen suppressed inflammation and plaque-related pathology in an Alzheimer transgenic APPSw mouse model (Tg2576), excessive use of NSAIDs targeting cyclooxygenase I can cause gastrointestinal, liver, and renal toxicity. One alternative NSAID is curcumin, derived from the curry spice turmeric. Curcumin has an extensive history as a food additive and herbal medicine in India and is also a potent polyphenolic antioxidant. To evaluate whether it could affect Alzheimer-like pathology in the APPSw mice, we tested a low (160 ppm) and a high dose of dietary curcumin (5000 ppm) on inflammation, oxidative damage, and plaque pathology. Low and high doses of curcumin significantly lowered oxidized proteins and interleukin-1beta, a proinflammatory cytokine elevated in the brains of these mice. With low-dose but not high-dose curcumin treatment, the astrocytic marker GFAP was reduced, and insoluble beta-amyloid (Abeta), soluble Abeta, and plaque burden were significantly decreased by 43-50%. However, levels of amyloid precursor (APP) in the membrane fraction were not reduced. Microgliosis was also suppressed in neuronal layers but not adjacent to plaques. In view of its efficacy and apparent low toxicity, this Indian spice component shows promise for the prevention of Alzheimer's disease

165. Lue LF, Walker DG, Rogers J (2001) Modeling Microglial activation in Alzheimer's disease with human postmortem Microglial cultures. Neurobiol.Aging 22:945-956
     Abstract: Alzheimer's disease (AD) is a uniquely human disorder. Despite intense research, the lack of availability of model systems has hindered AD studies though in recent years transgenic mouse models have been produced, which develop AD-like amyloid beta peptide (Abeta) plaques. For the study of inflammatory changes in AD brains, these transgenic mice may have limitations due to differences in the innate immune system of humans and rodents. Many studies of inflammatory processes in AD have focused on the role of activated Microglia. Over the last 8 years, our research has focused on the properties of human Microglia cultured from brain tissues of AD and non-demented (ND) individuals. As these are the cells observed to be activated in AD tissues, they represent a useful system for modeling the inflammatory components of AD.In this review, we summarize data by our group and others on the use of Microglia for AD-related inflammatory research, with emphasis on results using human postmortem brain Microglia. A range of products have been shown to be produced by human postmortem Microglia, both constitutively and in response to treatment with Abeta, including proinflammatory cytokines such as interleukin (IL)-1beta, IL-6, tumor necrosis factor (TNF) alpha, and macrophage colony stimulating factor (M-CSF), along with complement proteins, especially C1q, superoxide radicals and neurotoxic factors. In our studies, we have demonstrated that there was a significant difference between AD and ND Microglia in terms of their secretion of M-CSF and C1q. We also discuss the role of putative Abeta Microglial receptors, particular recent data showing a role for the receptor for advanced glycation endproducts (RAGE) in mediating the responses of human Microglia to Abeta. Finally, our studies on the use of an Abeta spot paradigm to model Microglia interactions with plaques demonstrated that many of the features of AD inflammation can be modeled with postmortem brain derived Microglia

166. Lue LF, Rydel R, Brigham EF, Yang LB, Hampel H, Murphy GM, Jr., Brachova L, Yan SD, Walker DG, Shen Y, Rogers J (2001) Inflammatory repertoire of Alzheimer's disease and nondemented elderly Microglia in vitro. Glia 35:72-79
     Abstract: We have previously developed and characterized isolated Microglia and astrocyte cultures from rapid (<4 h) brain autopsies of Alzheimer's disease (AD) and nondemented elderly control (ND) patients. In the present study, we evaluate the inflammatory repertoire of AD and ND Microglia cultured from white matter (corpus callosum) and gray matter (superior frontal gyrus) with respect to three major proinflammatory cytokines, three chemokines, a classical pathway complement component, a scavenger cell growth factor, and a reactive nitrogen intermediate. Significant, dose-dependent increases in the production of pro-interleukin-1beta (pro-IL-1beta), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha), monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory peptide-1alpha (MIP-1alpha), IL-8, and macrophage colony-stimulating factor (M-CSF) were observed after exposure to pre-aggregated amyloid beta peptide (1-42) (Abeta1-42). Across constitutive and Abeta-stimulated conditions, secretion of complement component C1q, a reactive nitrogen intermediate, and M-CSF was significantly higher in AD compared with ND Microglia. Taken together with previous in situ hybridization findings, these results demonstrate unequivocally that elderly human Microglia provide a brain endogenous source for a wide range of inflammatory mediators

167. Lue LF, Walker DG, Brachova L, Beach TG, Rogers J, Schmidt AM, Stern DM, Yan SD (2001) Involvement of Microglial receptor for advanced glycation endproducts (RAGE) in Alzheimer's disease: identification of a cellular activation mechanism. Exp.Neurol. 171:29-45
     Abstract: Receptor-mediated interactions with amyloid beta-peptide (Abeta) could be important in the evolution of the inflammatory processes and cellular dysfunction that are prominent in Alzheimer's disease (AD) pathology. One candidate receptor is the receptor for advanced glycation endproducts (RAGE), which can bind Abeta and transduce signals leading to cellular activation. Data are presented showing a potential mechanism for Abeta activation of Microglia that could be mediated by RAGE and macrophage colony-stimulating factor (M-CSF). Using brain tissue from AD and nondemented (ND) individuals, RAGE expression was shown to be present on Microglia and neurons of the hippocampus, entorhinal cortex, and superior frontal gyrus. The presence of increased numbers of RAGE-immunoreactive Microglia in AD led us to further analyze RAGE-related properties of these cells cultured from AD and ND brains. Direct addition of Abeta(1-42) to the Microglia increased their expression of M-CSF. This effect was significantly greater in Microglia derived from AD brains compared to those from ND brains. Increased M-CSF secretion was also demonstrated using a cell culture model of plaques whereby Microglia were cultured in wells containing focal deposits of immobilized Abeta(1-42). In each case, the Abeta stimulation of M-CSF secretion was significantly blocked by treatment of cultures with anti-RAGE F(ab')2. Treatment of Microglia with anti-RAGE F(ab')2 also inhibited the chemotactic response of Microglia toward Abeta(1-42). Finally, incubation of Microglia with M-CSF and Abeta increased expression of RAGE mRNA. These Microglia also expressed M-CSF receptor mRNA. These data suggest a positive feedback loop in which Abeta-RAGE-mediated Microglial activation enhances expression of M-CSF and RAGE, possibly initiating an ascending spiral of cellular activation

168. Malchiodi-Albedi F, Domenici MR, Paradisi S, Bernardo A, Ajmone-Cat MA, Minghetti L (2001) Astrocytes contribute to neuronal impairment in beta A toxicity increasing apoptosis in rat hippocampal neurons. Glia 34:68-72
     Abstract: Astrocytosis is a common feature of amyloid plaques, the hallmark of Alzheimer's disease (AD), along with activated Microglia, neurofibrillary tangles, and beta-amyloid (beta A) deposition. However, the relationship between astrocytosis and neurodegeneration remains unclear. To assess whether beta A-stimulated astrocytes can damage neurons and contribute to beta A neurotoxicity, we studied the effects of beta A treatment in astrocytic/neuronal co-cultures, obtained from rat embryonic brain tissue. We found that in neuronal cultures conditioned by beta A-treated astrocytes, but not directly in contact with beta A, the number of apoptotic cells increased, doubling the values of controls. In astrocytes, beta A did not cause astrocytic cell death, nor did produce changes in nitric oxide or prostaglandin E(2) levels. In contrast, S-100 beta expression was remarkably increased. Our data show for the first time that beta A--astrocytic interaction produces a detrimental effect on neurons, which may contribute to neurodegeneration in AD

169. Martins RN, Taddei K, Kendall C, Evin G, Bates KA, Harvey AR (2001) Altered expression of apolipoprotein E, amyloid precursor protein and presenilin-1 is associated with chronic reactive gliosis in rat cortical tissue. Neuroscience 106:557-569
     Abstract: A major characteristic feature of Alzheimer's disease is the formation of compact, extracellular deposits of beta-amyloid (senile plaques). These deposits are surrounded by reactive astrocytes, Microglia and dystrophic neurites. Mutations in three genes have been implicated in early-onset familial Alzheimer's disease. However, inflammatory changes and astrogliosis are also believed to play a role in Alzheimer's pathology. What is unclear is the extent to which these factors initiate or contribute to the disease progression. Previous rat studies demonstrated that heterotopic transplantation of foetal cortical tissue onto the midbrain of neonatal hosts resulted in sustained glial reactivity for many months. Similar changes were not seen in cortex-to-cortex grafts. Using this model of chronic cortical gliosis, we have now measured reactive changes in the levels of the key Alzheimer's disease proteins, namely the amyloid precursor protein, apolipoprotein E and presenilin-1. These changes were visualised immunohistochemically and were quantified by western blot analysis. We report here that chronic cortical gliosis in the rat results in a sustained increase in the levels of apolipoprotein E and total amyloid precursor protein. Reactive astrocytes in heterotopic cortical grafts were immunopositive for both of these proteins. Using a panel of amyloid precursor protein antibodies we demonstrate that chronic reactive gliosis is associated with alternative cleavage of the peptide. No significant changes in apolipoprotein E or amyloid precursor protein expression were seen in non-gliotic cortex-to-cortex transplants. Compared to host cortex, the levels of both N-terminal and C-terminal fragments of presenilin-1 were significantly lower in gliotic heterotopic grafts.The changes described here largely mirror those seen in the cerebral cortex of humans with Alzheimer's disease and are consistent with the proposal that astrogliosis may be an important factor in the pathogenesis of this disease

170. Masliah E, Ho G, Wyss-Coray T (2001) Functional role of TGF beta in Alzheimer's disease microvascular injury: lessons from transgenic mice. Neurochem.Int. 39:393-400
     Abstract: Recent studies have implicated pro- and anti-inflammatory cytokines as integral to Alzheimer's disease (AD) pathogenesis. Among them, transforming growth factor-beta (TGF-beta) is emerging as an important factor in regulating inflammatory responses. This multifunctional cytokine might be centrally involved in several aspects of AD pathogenesis by regulating beta-amyloid precursor protein synthesis and processing, plaque formation, astroglial and Microglial response and neuronal cell death. Among all of these potential roles, studies in transgenic and infusion animal models have shown that TGF-beta may primarily contribute to AD pathogenesis by influencing A beta production and deposition, which in turn might result in damage to the brain microvasculature. The lessons learned from these models are of great interest not only for understanding of the role of TGF-beta in AD, but also for future treatments where testing of anti-inflammatory agents such as ibuprofen and an amyloid vaccine hold great promise. In this regard, further elucidation of the signal pathways by which TGF-beta exerts its effect in AD might lead to specific targets for further therapeutic intervention

171. Matsuoka Y, Picciano M, Malester B, LaFrancois J, Zehr C, Daeschner JM, Olschowka JA, Fonseca MI, O'Banion MK, Tenner AJ, Lemere CA, Duff K (2001) Inflammatory responses to amyloidosis in a transgenic mouse model of Alzheimer's disease. Am.J.Pathol. 158:1345-1354
     Abstract: Mutations in the amyloid precursor protein (APP) and presenilin-1 and -2 genes (PS-1, -2) cause Alzheimer's disease (AD). Mice carrying both mutant genes (PS/APP) develop AD-like deposits composed of beta-amyloid (Abeta) at an early age. In this study, we have examined how Abeta deposition is associated with immune responses. Both fibrillar and nonfibrillar Abeta (diffuse) deposits were visible in the frontal cortex by 3 months, and the amyloid load increased dramatically with age. The number of fibrillar Abeta deposits increased up to the oldest age studied (2.5 years old), whereas there were less marked changes in the number of diffuse deposits in mice over 1 year old. Activated Microglia and astrocytes increased synchronously with amyloid burden and were, in general, closely associated with deposits. Cyclooxygenase-2, an inflammatory response molecule involved in the prostaglandin pathway, was up-regulated in astrocytes associated with some fibrillar deposits. Complement component 1q, an immune response component, strongly colocalized with fibrillar Abeta, but was also up-regulated in some plaque-associated Microglia. These results show: i) an increasing proportion of amyloid is composed of fibrillar Abeta in the aging PS/APP mouse brain; ii) Microglia and astrocytes are activated by both fibrillar and diffuse Abeta; and iii) cyclooxygenase-2 and complement component 1q levels increase in response to the formation of fibrillar Abeta in PS/APP mice

172. Mattson MP, Camandola S (2001) NF-kappaB in neuronal plasticity and neurodegenerative disorders. J.Clin.Invest 107:247-254

173. Meda L, Baron P, Scarlato G (2001) Glial activation in Alzheimer's disease: the role of Abeta and its associated proteins. Neurobiol.Aging 22:885-893
     Abstract: A common feature of Alzheimer's disease (AD) pathology is the abundance of reactive astrocytes and activated Microglia in close proximity to neuritic plaques containing amyloid-beta protein (Abeta). The relationship between glial activation and neurodegeneration remains unclear, although several cytokines and inflammatory mediators produced by activated glia have the potential to initiate or exacerbate the progression of neuropathology. Assuming that glial activation plays a central role in the development and progression of AD, a prominent feature is to understand which stimuli drive this activation in senile plaques and to define their effects in vitro. There is a growing body of evidence to suggest that deposition of Abeta and expression of its associated molecules represent important trigger factors in glial activation leading to an inflammatory reaction in the brain. Thus, unraveling the mechanisms by which these proteins exert their effect on glial cells may provide significant insight into the pathophysiology of AD, and may lead to the identification of new strategies for AD treatment

174. Moreno-Flores MT, Martin-Aparicio E, Salinero O, Wandosell F (2001) Fibronectin modulation by A beta amyloid peptide (25-35) in cultured astrocytes of newborn rat cortex. Neurosci.Lett. 314:87-91
     Abstract: Fibronectin appears to be present in Senile Plaques of Alzheimer's disease brains. These senile or neuritic plaques are surrounded by dystrophic neurites, activated Microglia and reactive astrocytes. The purpose of this work was to establish if a direct correlation exists between the production of Fibronectin (FN) by astrocytes and the presence of amyloid, analysing the modification of this protein produced after the treatment of cultured astrocytes with amyloid peptide (25-35). Our data showed that the addition of previously polymerised A beta-peptide to cultured astrocytes induced a marked increase in FN immunoreactivity that is in part dependent on phosphatases 2A or phosphatase 1, since was partially inhibited by okadaic acid. The increased amount of FN did not appear to be associated to any specific single isoform of which are mainly present in the rat brain. Our data suggest that in vivo FN accumulated in senile plaques may be the result, at least in part, of the response of reactive astrocyte to the presence of amyloid peptide. The importance of FN up-regulation in vivo, as part of a 'positive' response of the astrocytes to produce molecules that favours neurite outgrowth, is discussed

175. Mrak RE, Griffinbc WS (2001) The role of activated astrocytes and of the neurotrophic cytokine S100B in the pathogenesis of Alzheimer's disease. Neurobiol.Aging 22:915-922
     Abstract: Activated astrocytes, overexpressing the neurotrophic signaling molecule S100beta, are invariant components of the Abeta plaques of Alzheimer's disease. Even early, nonfibrillar amyloid deposits in Alzheimer's disease contain such astrocytes, and the numbers and degree of activation of these wax and wane with the subsequent neuritic pathology of plaque evolution. Astrocytic overexpression of S100B in the neuritic plaques of Alzheimer's disease correlates with the degree of neuritic pathology in Abeta plaques in this disease, suggesting a pathogenic role for S100B's neurotrophic properties in the evolution of these lesions. Astrocytic overexpression of S100B, in turn, is promoted by high levels of interleukin-1 (IL-1), originating from activated Microglia that are also constant components of Abeta plaques in Alzheimer's disease. Similar patterns of astrocyte activation, S100B overexpression, Microglial activation, and IL-1 overexpression are seen in conditions that confer risk for Alzheimer's disease (aging, head trauma, Down's syndrome), in conditions that predispose to accelerated appearance of Alzheimer-like neuropathologic changes (chronic epilepsy, HIV infection), and in animal models of Alzheimer's disease. These cells and molecules are an important components of a cytokine cycle of molecular and cellular cascades that may drive disease progression in Alzheimer's disease

176. Muehlhauser F, Liebl U, Kuehl S, Walter S, Bertsch T, Fassbender K (2001) Aggregation-Dependent interaction of the Alzheimer's beta-amyloid and Microglia. Clin.Chem.Lab Med. 39:313-316
     Abstract: Chronic glial activation possibly plays a role in chronic neurodegeneration in Alzheimer's disease (AD). It has been shown that amyloid peptide is capable of activating Microglial cells in vitro. The aim of this study was to further characterize the structural preconditions for amyloid peptide in order to activate glial cells and to investigate whether this peptide is also able to induce glial activation in the living brain. We observed that amyloid peptide induced strong cellular activation in primary Microglial cell culture as detected by the release of stable metabolites of nitric oxide (NO), when the peptide was fibrillar. For this activation, co-stimulation with interferon-gamma was a precondition. Using microdialysis of the living brain in a rat we observed pronounced NO generation when fibrillar amyloid peptide was stereotaxically injected. Non-fibrillar amyloid peptide did not induce such a glial reaction. No administration of interferon-gamma or any other co-stimulatory factor was necessary in vivo. Thus, we show that fibrillar, but not non-fibrillar amyloid peptide induced glial activation also in vivo. In the case of the living brain, the presence of deposits of fibrillar amyloid peptide could maintain a chronic Microglial activation, ultimately leading to the progressive neurodegeneration associated with Alzheimer's disease

177. Nilsson LN, Das S, Potter H (2001) Effect of cytokines, dexamethasone and the A/T-signal peptide polymorphism on the expression of alpha(1)-antichymotrypsin in astrocytes: significance for Alzheimer's disease. Neurochem.Int. 39:361-370
     Abstract: Proinflammatory cytokines and acute phase proteins, such as alpha(1)-antichymotrypsin, are over expressed in Microglia and astrocytes in brain regions with abundant mature amyloid plaques, suggesting a glial cell-led brain acute phase response in the Alzheimer neuropathology. In this paper, we show that alpha(1)-antichymotrypsin gene expression in human astrocytes is elevated by interleukin-1 and interleukin-6, and further enhanced by glucocorticoid, while the homologous contrapsin gene in rat astrocytes is unaffected by these cytokines. These distinct gene regulation mechanisms might help to explain the differential susceptibility of humans and rodents to amyloid formation of the Alzheimer's type. In addition, we demonstrate that the alpha(1)-antichymotrypsin A-allele that encodes a different signal peptide and is a suggested risk factor for Alzheimer's disease gives rise to a reduced level of immature alpha(1)-antichymotrypsin in transfected cells. The physiological result would be an enhanced ability of the A-encoded alpha(1)-antichymotrypsin protein to become secreted and promote extracellular amyloid formation. We discuss our findings in terms of a model in which cytokine-induced alpha(1)-antichymotrypsin synthesis in astrocytes constitutes a specific inflammatory pathway that accelerates the development of Alzheimer's disease and could at least partly underlie the regional specificity and species restriction of the neuropathology

178. Petegnief V, Saura J, Gregorio-Rocasolano N, Paul SM (2001) Neuronal injury-induced expression and release of apolipoprotein E in mixed neuron/glia co-cultures: nuclear factor kappaB inhibitors reduce basal and lesion-induced secretion of apolipoprotein E. Neuroscience 104:223-234
     Abstract: In order to better delineate the intracellular signaling pathways underlying glial apolipoprotein E (apoE) expression and release, we have characterized an in vitro model of induction of glial apoE production induced by neuronal death. Exposure of mixed fetal cortical neuron/glia co-cultures to the neurotoxin N-methyl-D-aspartate results in increased apoE expression and release in a time- and concentration-dependent manner. Increased expression of apoE messenger RNA precedes the increase in intracellular apoE, followed by accumulation of the holoprotein in the culture medium. Neuronal injury induced by N-methyl-D-aspartate is accompanied by a reactive astrogliosis as measured by an increase in glial fibrillary acidic protein messenger RNA and protein at 48 and 72h post-lesion, respectively. A similar microgliosis was observed using the Microglial marker ED-1. Neuronal injury-induced glial apoE secretion is attenuated by the nuclear factor kappaB inhibitors, aspirin, Bay 11-7082 and MG-132, suggesting that this transcription factor is involved in both constitutive and induced glial apoE expression.The present data show that up-regulation of apoE is an early event in the glial activation triggered by neurodegeneration in vitro and that activation of nuclear factor kappaB directly or indirectly mediates the increase in apoE expression

179. Picklo MJ, Sr., Olson SJ, Hayes JD, Markesbery WR, Montine TJ (2001) Elevation of AKR7A2 (succinic semialdehyde reductase) in neurodegenerative disease. Brain Res. 916:229-238
     Abstract: Elevated levels of oxidative stress or decreased antioxidant defense mechanisms may underlie the regionally increased oxidative damage to brain observed in many neurodegenerative disorders. Phase I detoxification pathways for reactive aldehydes generated from lipid peroxidation include aldehyde dehydrogenases, alcohol dehydrogenases and aldo-keto reductases (AKR). In the present study, we examined the cellular expression of AKR family member, succinic semialdehyde reductase (AKR7A2) that reduces toxic aldehydes as well as catalyzing the biosynthesis of the neuromodulator gamma-hydroxybutyrate (GHB). Our results show that in the cerebral cortex and hippocampus, AKR7A2 is primarily localized to glial cells, astrocytes and Microglia. In the midbrain, AKR7A2 was found in glia and neuromelanin-containing neurons of the substantia nigra, and the periaqueductal gray. In sections of cerebral cortex and hippocampus from patients with AD and DLB, AKR7A2 immunoreactivity was elevated in reactive astrocytes and Microglial cells. Furthermore, total AKR7A2 protein levels were elevated in the cerebral cortex of patients with AD versus control individuals. Our data suggest that reactive gliosis, as a response to injury, may affect GHB neuromodulatory pathways in neurodegenerative disease and elevate aldehyde detoxification pathways

180. Platt B, Fiddler G, Riedel G, Henderson Z (2001) Aluminium toxicity in the rat brain: histochemical and immunocytochemical evidence. Brain Res.Bull. 55:257-267
     Abstract: Although the neurotoxic actions of aluminium (Al) have been well documented, its contribution to neurodegenerative diseases such as Alzheimer's disease remains controversial. In the present study, we applied histochemical techniques to identify changes induced by intracerebroventricular Al injections (5.4 microg in 5.5 microl, daily over a period of 5 successive days) in the adult rat brain after survival periods of either 1 or 6 weeks. For both Al- and saline-infused controls, no major signs of gross histological changes were evident in cresyl violet-stained sections. Al (as indicated by the fluorescent Morin staining) was concentrated in white matter of the medial striatum, corpus callosum, and cingulate bundle. Immunoreactivity of astrocytes and phagocytic Microglia based on glial fibrillary acidic protein and ED1 markers, respectively, revealed a greater inflammatory response in Al-injected animals compared to controls. Damage of the cingulate bundle in Al-treated animals led to a severe anterograde degeneration of cholinergic terminals in cortex and hippocampus, as indicated by acetylcholinesterase labelling. Our data suggest that the enhancement of inflammation and the interference with cholinergic projections may be the modes of action through which Al may cause learning and memory deficits, and contribute to pathological processes in Alzheimer's disease

181. Pocock JM, Liddle AC (2001) Microglial signalling cascades in neurodegenerative disease. Prog.Brain Res. 132:555-565
     Abstract: Activated Microglia release a number of substances, the specific cocktail released depending on the stimulus. Many of the substances released by Microglia also serve to activate them, suggesting the presence of a number of autocrine/paracrine loops. Because of the low density of Microglia present in the normal brain, such autocrine/paracrine loops may not be significant but during the initiation and ongoing states of neurodegeneration, the increased concentrations of Microglia may allow the activation and escalated stimulation of these feedback pathways. The activation of p38 MAPK by A beta and cytokines may be part of a Microglial autocrine loop which results in the fueling of the Microglial inflammatory response. A novel class of cytokine suppressive anti-inflammatory drugs (CSAIDs) inhibit the activation of p38 kinase (Bhat et al., 1998) suggesting this kinase plays a key role in transducing Microglial responses to activation stimuli (Badger et al., 1996)

182. Potter H, Wefes IM, Nilsson LN (2001) The inflammation-induced pathological chaperones ACT and apo-E are necessary catalysts of Alzheimer amyloid formation. Neurobiol.Aging 22:923-930
     Abstract: Biochemical, genetic, and epidemiological evidence indicates that inflammation is an essential part of the pathogenesis of Alzheimer's disease. Over the last decade, we and others have focused on the mechanism by which specific inflammatory molecules contribute to the Alzheimer pathogenic pathway. In particular, we have learned that several acute phase/inflammatory molecules, specifically alpha(1)-antichymotrypsin (ACT) and apolipoprotein E (apoE) that are overproduced in the AD brain can promote the formation of, and are associated with, the neurotoxic amyloid deposits that are a key pathological hallmark of the disease. Because both of these proteins bind to the Abeta peptide and catalyze its polymerization into amyloid filaments, they have been termed "pathological chaperones".ACT, and, to a lesser extent, apoE are greatly overproduced only in areas of the AD brain that are prone to amyloid formation. This restriction suggests a local inflammatory reaction may underlie the regional specificity of amyloid deposition by inducing the production of pathological chaperones. The data that will be discussed indicate that ACT over-expression is caused by the activation of ACT mRNA synthesis in astrocytes in response to increased production of the inflammatory cytokine IL-1. IL-1 is released from Microglia that become activated by pre-amyloid seeds of Abeta. Recently, this inflammatory cascade has been extended to include the amyloid precursor protein (APP), for IL-1 also upregulates the production of APP in astrocytes, but at the translational rather that the transcriptional level. Thus many of the key elements of the Alzheimer's disease pathogenic pathway are products of a local inflammatory reaction in the brain.Further support for a mechanistic role of inflammation in the Alzheimer's disease pathogenic pathway has been provided by genetic studies, which have associated an increased risk of developing AD with specific polymorphisms in the apoE, ACT, and the IL-1 genes. Most recently, transgenic mouse models of AD have demonstrated that ACT and apoE are amyloid promoters/pathological chaperones in vivo whose contribution is necessary for both amyloid formation and for amyloid-associated cognitive decline and memory loss.The importance of these findings is that they help to place inflammation at the center of the pathogenic pathway to Alzheimer's disease and identify specific steps in the pathway that may be amenable to therapeutic intervention

183. Rempel H, Kusdra L, Pulliam L (2001) Interleukin-1beta up-regulates expression of neurofilament light in human neuronal cells. J.Neurochem. 78:640-645
     Abstract: Elevated expression of interleukin-1 (IL-1beta), a pro-inflammatory cytokine secreted by activated Microglia, is a pathogenic marker of numerous neurodegenerative processes including Alzheimer's disease (AD). We have characterized a link between IL-1beta and the 68-kDa neurofilament light (NF-L) protein, which is a major component of the neuronal cytoskeleton. Using human brain aggregate cultures, we found that IL-1beta treatment significantly increased NF-L expression in primary neurons. Analysis of mRNA levels demonstrated elevated NF-L expression within 72 h while imaging of neurons by immunofluorescent staining for NF-L confirmed IL-1beta-induced NF-L protein expression. These observations suggest a potential inflammatory-induced mechanism for deregulation of an important cytoskeletal protein, NF-L, possibly leading to neuronal dysfunction

184. Rogers J, Lue LF (2001) Microglial chemotaxis, activation, and phagocytosis of amyloid beta-peptide as linked phenomena in Alzheimer's disease. Neurochem.Int. 39:333-340
     Abstract: Microglia are widely held to play important pathophysiologic roles in Alzheimer's disease (AD). On exposure to amyloid beta peptide (A beta) they exhibit chemotactic, phagocytic, phenotypic and secretory responses consistent with scavenger cell activity in a localized inflammatory setting. Because AD Microglial chemotaxis, phagocytosis, and secretory activity have common, tightly linked soluble intermediaries (e.g., cytokines, chemokines), cell surface intermediaries (e.g., receptors, opsonins), and stimuli (e.g., highly inert A beta deposits and exposed neurofibrilly tangles), the mechanisms for Microglial clearance of A beta are necessarily coupled to localized inflammatory mechanisms that can be cytotoxic to nearby tissue. This presents a critical dilemma for strategies to remove A beta by enhancing micoglial activation--a dilemma that warrants substantial further investigation

185. Schubert P, Ogata T, Marchini C, Ferroni S (2001) Glia-related pathomechanisms in Alzheimer's disease: a therapeutic target? Mech.Ageing Dev. 123:47-57
     Abstract: Reactive glial cell properties could contribute to pathomechanisms underlying Alzheimer's disease by favoring oxidative neuronal damage and beta-amyloid toxicity. A critical step is apparently reached when pathological glia activation is no longer restricted to Microglia and includes astrocytes. By giving up their differentiated state, astrocytes may lose their physiological negative feed-back control on Microglial NO production and even contribute to neurotoxic peroxynitrate formation. Another consequence is the impairment of the astrocyte-maintained extracellular ion homeostasis favoring excitotoxic damage. By the production of apolipoprotein-E, triggered by the Microglial cytokine interleukine-1beta, reactive astrocytes could promote the transformation of beta-amyloid into the toxic form. A pharmacologically reinforced cAMP signaling in rat glial cell cultures depressed oxygen radical formation in Microglia and their release of TNF-alpha and interleukine-1beta, feed-forward signals which mediate oxidative damage and secondary astrocyte activation. Cyclic AMP also favored differentiation and expression of a mature ion channel pattern in astrocytes improving their glutamate buffering. A deficient cholinergic signaling that increases the risk of pathological APP processing was compensated by an adenosine-mediated reinforcement of the second messenger calcium. A combination therapy with acetylcholine-esterase inhibitors together with adenosine raising pharmaca, therefore, may be used to treat cholinergic deficiency in Alzheimer's disease

186. Sheng JG, Jones RA, Zhou XQ, McGinness JM, Van Eldik LJ, Mrak RE, Griffin WS (2001) Interleukin-1 promotion of MAPK-p38 overexpression in experimental animals and in Alzheimer's disease: potential significance for tau protein phosphorylation. Neurochem.Int. 39:341-348
     Abstract: Activated (phosphorylated) mitogen-activated protein kinase p38 (MAPK-p38) and interleukin-1 (IL-1) have both been implicated in the hyperphosphorylation of tau, a major component of the neurofibrillary tangles in Alzheimer's disease. This, together with findings showing that IL-1 activates MAPK-p38 in vitro and is markedly overexpressed in Alzheimer brain, suggest a role for IL-1-induced MAPK-p38 activation in the genesis of neurofibrillary pathology in Alzheimer's disease. We found frequent colocalization of hyperphosphorylated tau protein (AT8 antibody) and activated MAPK-p38 in neurons and in dystrophic neurites in Alzheimer brain, and frequent association of these structures with activated Microglia overexpressing IL-1. Tissue levels of IL-1 mRNA as well as of both phosphorylated and non-phosphorylated isoforms of tau were elevated in these brains. Significant correlations were found between the numbers of AT8- and MAPK-p38-immunoreactive neurons, and between the numbers of activated Microglia overexpressing IL-1 and the numbers of both AT8- and MAPK-p38-immunoreactive neurons. Furthermore, rats bearing IL-1-impregnated pellets showed a six- to seven-fold increase in the levels of MAPK-p38 mRNA, compared with rats with vehicle-only pellets (P<0.0001). These results suggest that Microglial activation and IL-1 overexpression are part of a feedback cascade in which MAPK-p38 overexpression and activation leads to tau hyperphosphorylation and neurofibrillary pathology in Alzheimer's disease

187. Sigurdsson EM, Scholtzova H, Mehta PD, Frangione B, Wisniewski T (2001) Immunization with a nontoxic/nonfibrillar amyloid-beta homologous peptide reduces Alzheimer's disease-associated pathology in transgenic mice. Am.J.Pathol. 159:439-447
     Abstract: Transgenic mice with brain amyloid-beta (Abeta) plaques immunized with aggregated Abeta1-42 have reduced cerebral amyloid burden. However, the use of Abeta1-42 in humans may not be appropriate because it crosses the blood brain barrier, forms toxic fibrils, and can seed fibril formation. We report that immunization in transgenic APP mice (Tg2576) for 7 months with a soluble nonamyloidogenic, nontoxic Abeta homologous peptide reduced cortical and hippocampal brain amyloid burden by 89% (P = 0.0002) and 81% (P = 0.0001), respectively. Concurrently, brain levels of soluble Abeta1-42 were reduced by 57% (P = 0.0019). Ramified Microglia expressing interleukin-1beta associated with the Abeta plaques were absent in the immunized mice indicating reduced inflammation in these animals. These promising findings suggest that immunization with nonamyloidogenic Abeta derivatives represents a potentially safer therapeutic approach to reduce amyloid burden in Alzheimer's disease, instead of using toxic Abeta fibrils

188. Silva I, Mor G, Naftolin F (2001) Estrogen and the aging brain. Maturitas 38:95-100
     Abstract: Evidence is presented indicating a role for estrogen in the function and maintenance of the aging brain. Based on complementary data that estrogen regulates the function of the immune--brain barrier, the hypothesis is presented that estrogen contributes to brain homeostasis via regulation of Microglial activation, enabling immune-privileged status in the brain. Diminished estrogen levels during the menopause compromise the immune--brain barrier fostering inflammatory processes in the brain. This has potentially lethal consequences for brain cells, and may contribute to brain pathologies such as Alzheimer's disease

189. Skovronsky DM, Fath S, Lee VM, Milla ME (2001) Neuronal localization of the TNFalpha converting enzyme (TACE) in brain tissue and its correlation to amyloid plaques. J.Neurobiol. 49:40-46
     Abstract: The tumor necrosis factor (TNF)-alpha converting enzyme (TACE) can cleave the cell-surface ectodomain of the amyloid-beta precursor protein (APP), thus decreasing the generation of amyloid-beta (Abeta) by cultured non-neuronal cells. While the amyloidogenic processing of APP in neurons is linked to the pathogenesis of Alzheimer's disease (AD), the expression of TACE in neurons has not yet been examined. Thus, we assessed TACE expression in a series of neuronal and non-neuronal cell types by Western blots. We found that TACE was present in neurons and was only faintly detectable in lysates of astrocytes, oligodendrocytes, and Microglial cells. Immunohistochemical analysis was used to determine the cellular localization of TACE in the human brain, and its expression was detected in distinct neuronal populations, including pyramidal neurons of the cerebral cortex and granular cell layer neurons in the hippocampus. Very low levels of TACE were seen in the cerebellum, with Purkinje cells at the granular-molecular boundary staining faintly. Because TACE was localized predominantly in areas of the brain that are affected by amyloid plaques in AD, we examined its expression in a series of AD brains. We found that AD and control brains showed similar levels of TACE staining, as well as similar patterns of TACE expression. By double labeling for Abeta plaques and TACE, we found that TACE-positive neurons often colocalized with amyloid plaques in AD brains. These observations support a neuronal role for TACE and suggest a mechanism for its involvement in AD pathogenesis as an antagonist of Abeta formation

190. Stalder M, Deller T, Staufenbiel M, Jucker M (2001) 3D-Reconstruction of Microglia and amyloid in APP23 transgenic mice: no evidence of intracellular amyloid. Neurobiol.Aging 22:427-434
     Abstract: Microglia cells are closely associated with compact amyloid plaques in Alzheimer's disease (AD) brains. Although activated Microglia seem to play a central role in the pathogenesis of AD, mechanisms of Microglial activation by beta-amyloid as well as the nature of interaction between amyloid and Microglia remain poorly understood. We previously reported a close morphological association between activated Microglia and congophilic amyloid plaques in the brains of APP23 transgenic mice at both the light and electron microscopic levels [25]. In the present study, we have further examined the structural relationship between Microglia and amyloid deposits by using postembedding immunogold labeling, serial ultrathin sectioning, and 3-dimensional reconstruction. Although bundles of immunogold-labeled amyloid fibrils were completely engulfed by Microglial cytoplasm on single sections, serial ultrathin sectioning and three-dimensional reconstruction revealed that these amyloid fibrils are connected to extracellular amyloid deposits. These data demonstrate that extracellular amyloid fibrils form a myriad of finger-like channels with the widely branched Microglial cytoplasm. We conclude that in APP23 mice a role of Microglia in amyloid phagocytosis and intracellular production of amyloid is unlikely

191. Streit WJ, Conde JR, Harrison JK (2001) Chemokines and Alzheimer's disease. Neurobiol.Aging 22:909-913
     Abstract: In recent years, increasing attention has been focused on chemokines as inflammatory mediators in the CNS. The limited number of studies that have investigated chemokine and chemokine receptor expression in Alzheimer's disease (AD) brain and in cell culture models seem to support a role for inflammation in AD pathogenesis. Here we provide a review of these studies, but in addition, point out the possible role of chemokines as communication molecules between neurons and Microglia. Understanding neuron-Microglia interactions is essential for understanding AD pathogenesis, and disturbances in chemokine-mediated intercellular communication may contribute toward a generalized impairment of Microglial cell function

192. Szczepanik AM, Funes S, Petko W, Ringheim GE (2001) IL-4, IL-10 and IL-13 modulate A beta(1--42)-induced cytokine and chemokine production in primary murine Microglia and a human monocyte cell line. J.Neuroimmunol. 113:49-62
     Abstract: A hallmark of the immunopathology associated with Alzheimer's disease (AD) is the presence of activated Microglia surrounding senile plaque deposits of beta-amyloid (A beta) peptides. A beta peptides have been shown to be potent activators of Microglia and macrophages, but little is known about endogenous factors that may modulate their responses to amyloid. We investigated whether the 'anti-inflammatory' cytokines IL-4, IL-10 and IL-13 could regulate A beta-induced production of the inflammatory cytokines IL-1 alpha, IL-1 beta, TNF-alpha, IL-6 and the chemokine MCP-1. A beta(1-42) time- and dose-dependently induced the production and secretion of these inflammatory proteins in the human THP-1 monocyte cell line and in primary murine Microglia, similar to what was observed for lipopolysaccharide (LPS) stimulated cells. IL-10 was found to suppress all A beta and LPS-induced inflammatory proteins measured (IL-1 alpha, IL-1 beta, IL-6, TNF-alpha and MCP-1) in both cell types with the exception of LPS-induced MCP-1 in THP-1 cells where no change was observed. In contrast to the inhibition observed for IL-10, both IL-4 and IL-13 enhanced MCP-1 secretion. IL-4 and IL-13 reduced IL-6 secretion, but effects on IL-1 alpha, IL-1 beta or TNF-alpha were dependent on cell type and stimulus conditions. Additional experiments using RT-PCR showed that IL-4, IL-10 and IL-13 mRNA is found to be present in human brain tissue. These results show that IL-4, IL-10, and IL-13 differentially regulate Microglial responses to A beta and may play a role in the inflammation pathology observed surrounding senile plaques

193. Szpak GM, Lechowicz W, Lewandowska E, Bertrand E, Wierzba-Bobrowicz T, Gwiazda E, Schmidt-Sidor B, Dymecki J (2001) Neurones and Microglia in central nervous system immune response to degenerative processes. Part 1: Alzheimer's disease and Lewy body variant of Alzheimer's disease. Quantitative study. Folia Neuropathol. 39:181-192
     Abstract: The quantitative correlation between neurone loss and brain immune response, assessed by intensity of Microglia inflammatory reaction in cortical association area and limbic cortex, was investigated and compared in previously immunohistochemistry (IHC) and ultrastructural confirmed 11 cases of Alzheimer's disease (AD), 7 cases mixed form of Dementia with AD findings and Lewy bodies (AD/DLB) reported, in accordance with Consortium on Dementia, as Lewy body variant of AD (LBV) and 6 non-demented autopsy control cases from 63 to 86 years old. In the present work we investigated association and limbic cortical areas linked with memory mechanisms; there are regions characterised by early distribution of IHC confirmed AD and DLB/AD (LBV) markers, as well as a substantial physiological stability of neurone pool regardless of age. The results indicated that AD and LBV differ in their neurone loss intensity and inflammatory reaction, with much higher intensity in AD. In Alzheimer's disease, neurone loss in association temporal cortex made up 51% of control values with simultaneous 8-fold increase in the density of MHC II-positive activated Microglia, whereas in LBV, both the loss of neurone density and the increase in activated Microglia density, was not so high (up to 41% and 4-5-fold, respectively). Changes in the limbic cortex were less pronounced. A strong correlation in the clinical material between neurone loss and Microglia activation in both processes, especially in AD (r = 0.73), speaks in favour of the hypothesis on the neuronal immune surveillance and arousal of immune brain response in conditions of declining control, due to significant neurone loss in the neurodegenerative process. The inflammatory reaction of MHC II-immunoreactive Microglia, concomitant with neurodegenerative process, seems to be a consequence of increased immune response due to loss of neurones and weakening of their control upon immunosurveillance in central nervous system

194. Takeda A, Wakai M, Niwa H, Dei R, Yamamoto M, Li M, Goto Y, Yasuda T, Nakagomi Y, Watanabe M, Inagaki T, Yasuda Y, Miyata T, Sobue G (2001) Neuronal and glial advanced glycation end product [Nepsilon-(carboxymethyl)lysine]] in Alzheimer's disease brains. Acta Neuropathol.(Berl) 101:27-35
     Abstract: The cellular distribution of an advanced glycation end product [Nepsilon-(carboxymethyl)lysine (CML)] in aged and Alzheimer's disease (AD) brains was assessed immunohistochemically. CML was localized in the cytoplasm of neurons, astrocytes, and Microglia in both aged and AD brains. Glial deposition was far more marked in AD brains than in aged brains, and neuronal deposition was also increased. On electron microscopic immunohistochemistry, neuronal CML formed granular or linear deposits associated with lipofuscin, and glial deposits formed lines around the vacuoles. Neuronal and glial deposits were prominent throughout the cerebral cortex and hippocampus, but were sparse in the putamen, globus pallidus, substantia nigra, and cerebellum, with glial deposits being far more prominent in AD brains. The distribution of neuronal and glial deposits did not correspond with the distribution of AD pathology. The extent of CML deposits was inversely correlated with neurofibrillary tangle formation, particularly in the hippocampus. Most hippocampal pyramidal neurons with neurofibrillary tangles did not have CML, and most of the neurons with heavy CML deposits did not have neurofibrillary tangles. In the hippocampus, neuronal CML was prominent in the region where neuronal loss was mild. These observations suggest that CML deposition does not directly cause neurofibrillary tangle formation or neuronal loss in AD

195. Tarkowski E, Wallin A, Regland B, Blennow K, Tarkowski A (2001) Local and systemic GM-CSF increase in Alzheimer's disease and vascular dementia. Acta Neurol.Scand. 103:166-174
     Abstract: A growing body of evidence points out the potential role of inflammatory mechanisms in the pathophysiology of brain damage in dementia. The aim of the present study was to investigate patterns of local and systemic cytokine release in patients with Alzheimer's disease (AD) and vascular dementia (VAD). The intrathecal levels of cytokines were related to neuronal damage and cerebral apoptosis. Twenty patients with early AD and 26 patients with VAD were analyzed with respect to cerebrospinal fluid (CSF) and serum levels of pro- and anti-inflammatory cytokines. In addition, CSF levels of Fas/APO-1 and bcl-2, a measure for apoptosis, and Tau protein, a marker for neuronal degradation, were studied. Significantly increased CSF levels of GM-CSF but not of other cytokines were observed in both dementia groups. These patients displayed a significant correlation between the GM-CSF levels and the levels of Fas/APO-1 and Tau protein in CSF. Our study demonstrates an intrathecal production of GM-CSF, a cytokine stimulating Microglial cell growth and exerting inflammatogenic properties. It is suggested that GM-CSF once secreted induces programmed cell death in the brain tissue of patients with dementia

196. Town T, Tan J, Mullan M (2001) CD40 signaling and Alzheimer's disease pathogenesis. Neurochem.Int. 39:371-380
     Abstract: The interaction between CD40 and its cognate ligand, CD40 ligand, is a primary regulator of the peripheral immune response, including modulation of T lymphocyte activation, B lymphocyte differentiation and antibody secretion, and innate immune cell activation, maturation, and survival. Recently, we and others have identified CD40 expression on a variety of CNS cells, including endothelial cells, smooth muscle cells, astroglia and Microglia, and have found that, on many of these cells, CD40 expression is enhanced by pro-inflammatory stimuli. Importantly, the CD40-CD40 ligand interaction on Microglia triggers a series of intracellular signaling events that are discussed, beginning with Src-family kinase activation and culminating in Microglial activation as evidenced by tumor necrosis factor-alpha secretion. Based on the involvement of Microglial activation and brain inflammation in Alzheimer's disease pathogenesis, we have investigated co-stimulation of Microglia, smooth muscle, and endothelial cells with CD40 ligand in the presence of low doses of freshly solubilized amyloid-beta peptides. Data reviewed herein show that CD40 ligand and amyloid-beta act synergistically to promote pro-inflammatory responses by these cells, including secretion of interleukin-1 beta by endothelial cells and tumor necrosis factor-alpha by Microglia. As these cytokines have been implicated in neuronal injury, a comprehensive model of pro-inflammatory CD40 ligand and amyloid-beta initiated Alzheimer's disease pathogenesis (mediated by multiple CNS cells) is proposed

197. Viel JJ, McManus DQ, Smith SS, Brewer GJ (2001) Age- and concentration-dependent neuroprotection and toxicity by TNF in cortical neurons from beta-amyloid. J.Neurosci.Res. 64:454-465
     Abstract: The induction of an inflammatory response and release of cytokines such as TNF may be involved in the age-related etiology of Alzheimer disease (AD). In the brain, Microglia have been shown to produce a wide variety of immune mediators, including the pro-inflammatory cytokine tumor necrosis factor (TNF). We hypothesize that with age there is increased ability of Microglia to produce TNF or that age decreases the neuroprotective effect of TNF against beta-amyloid (Abeta) toxicity in neurons. We investigated the effects of Abeta(1-40) on TNF secretion from forebrain cultures of Microglia from embryonic, middle-age (9-month) and old (36-month) rats. Over the first 12 hr of exposure to 10 microM Abeta (1-40), Microglia from embryonic and old rats increase TNF secretion, although Microglia from middle-age rats did not produce detectable levels of TNF. When low concentrations of TNF are added to neurons together with Abeta (1-40) in the absence of exogenous antioxidants, neuroprotection for old neurons is significantly less than neuroprotection for middle-age neurons. In neurons from old rats, high levels of TNF together with Abeta are more toxic than in neurons from middle-age or embryonic rats. These results are discussed in relation to neuroprotection and toxicity of the age-related pathology of AD

198. von Bernhardi R, Ramirez G (2001) Microglia-astrocyte interaction in Alzheimer's disease: friends or foes for the nervous system? Biol.Res. 34:123-128
     Abstract: Brain glial cells secrete several molecules that can modulate the survival of neurons after various types of damage to the CNS. Activated Microglia and astrocytes closely associate to amyloid plaques in Alzheimer Disease (AD). They could have a role in the neurotoxicity observed in AD because of the inflammatory reaction they generate. There is controversy regarding the individual part played by the different glial cells, and the interrelationships between them. Both astrocytes and Microglia produce several cytokines involved in the inflammatory reaction. Moreover, the same cytokines may have different effects, depending on their concentration and the type of cells in the vicinity. In turn, the events occurring in response to injury may lead to changes in the nature and relative concentration of the various factors involved. To learn about these putative glial interrelationships, we examined some effects of astrocytes on Microglial activation

199. Walker DG, Lue LF, Beach TG (2001) Gene expression profiling of amyloid beta peptide-stimulated human post-mortem brain Microglia. Neurobiol.Aging 22:957-966
     Abstract: Activation of Microglia is a central part of the chronic inflammatory processes in Alzheimer's disease (AD). In the brains of AD patients, activated Microglia are associated with amyloid beta (Abeta) peptide plaques. A number of previous studies have shown that aggregated synthetic Abeta peptide activates cultured Microglia to produce a range inflammatory products. The full extent of the inflammatory response still remains to be determined. In this study, gene array technology was employed to investigate in a more extensive manner the consequences of Microglial activation by Abeta peptide. RNA was prepared from pooled samples of cortical human Microglia isolated from post-mortem cases and incubated with a low dose (2.5 microM) of Abeta1-42 (or peptide solvent) for 24 h. This material was used to prepare cDNA probes, which were used to detect the differential pattern of expressed genes on a 1,176 Clontech membrane gene array. Results obtained showed that 104 genes were either upregulated or downregulated by 1.67 fold or greater. The most highly induced genes belonged to the chemokine family with interleukin-8 (IL-8) expression being increased by 11.7 fold. Interestingly, many of the highly induced genes had been identified as being responsive to activation by the transcription factor NF-kappaB. A number of genes were downregulated. Thymosin beta, prothymosin alpha and parathymosin, all belonging to the same gene family, were downregulated. To validate these semi-quantitative results, the expression of intercellular adhesion molecule-1 (ICAM-1) and rhoB were measured by RT-PCR in samples of cDNA derived from Abeta and control stimulated human cortical Microglia. These results confirm the usefulness of the gene array approach for studying Abeta-mediated inflammatory processes

200. Wegiel J, Wang KC, Imaki H, Rubenstein R, Wronska A, Osuchowski M, Lipinski WJ, Walker LC, LeVine H (2001) The role of Microglial cells and astrocytes in fibrillar plaque evolution in transgenic APP(SW) mice. Neurobiol.Aging 22:49-61
     Abstract: Ultrastructural reconstruction of 27 fibrillar plaques in different stages of formation and maturation was undertaken to characterize the development of fibrillar plaques in the brains of human APP(SW) transgenic mice (Tg2576). The study suggests that Microglial cells are not engaged in Abeta removal and plaque degradation, but in contrast, are a driving force in plaque formation and development. Fibrillar Abeta deposition at the amyloid pole of Microglial cells appears to initiate three types of neuropil response: degeneration of neurons, protective activation of astrocytes, and attraction and activation of Microglial cells sustaining plaque growth. Enlargement of neuronal processes and synapses with accumulation of degenerated mitochondria, dense bodies, and Hirano-type bodies is the marker of toxic injury of neurons by fibrillar Abeta. Separation of amyloid cores from neurons and degradation of amyloid cores by cytoplasmic processes of hypertrophic astrocytes suggest the protective and defensive character of astrocytic response to fibrillar Abeta. The growth of cored plaque from a small plaque with one Microglial cell with an amyloid star and a few dystrophic neurites to a large plaque formed by several dozen Microglial cells seen in old mice is the effect of attraction and activation of Microglial cells residing outside of the plaque perimeter. This mechanism of growth of plaques appears to be characteristic of cored plaques in transgenic mice. Other features in mouse Microglial cells that are absent in human brain are clusters of vacuoles, probably of lysosomal origin. They evolve into circular cisternae and finally into large vacuoles filled with osmiophilic, amorphous material and bundles of fibrils that are poorly labeled with antibody to Abeta. Microglial cells appear to release large amounts of fibrillar Abeta and accumulate traces of fibrillar Abeta in a lysosomal pathway

201. Wilcock DM, Gordon MN, Ugen KE, Gottschall PE, DiCarlo G, Dickey C, Boyett KW, Jantzen PT, Connor KE, Melachrino J, Hardy J, Morgan D (2001) Number of Abeta inoculations in APP+PS1 transgenic mice influences antibody titers, Microglial activation, and congophilic plaque levels. DNA Cell Biol. 20:731-736
     Abstract: There have been several reports on the use of beta-amyloid (Abeta ) vaccination in different mouse models of Alzheimer's disease (AD) and its effects on pathology and cognitive function. In this report, the histopathologic findings in the APP+PS1 doubly transgenic mouse were compared after three, five, or nine Abeta inoculations. The number of inoculations influenced the effects of vaccination on Congo red levels, Microglia activation, and anti-Abeta antibody titers. After three inoculations, the antibody titer of transgenic mice was substantially lower than that found in nontransgenic animals. However, after nine inoculations, the levels were considerably higher in both genotypes and no longer distinguishable statistically. The number of inoculations influenced CD45 expression, an indicator of Microglial activation. There was an initial upregulation, which was significant after five inoculations, but by nine inoculations, the extent of Microglial activation was equivalent to that in mice given control vaccinations. Along with this increased CD45 expression, there was a correlative reduction in staining by Congo red, which stains compact plaques. When data from the mice from all groups were combined, there was a significant correlation between activation of Microglia and Congo red levels, suggesting that Microglia play a role in the clearance of compact plaque

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

203. Wong A, Luth HJ, Deuther-Conrad W, Dukic-Stefanovic S, Gasic-Milenkovic J, Arendt T, Munch G (2001) Advanced glycation endproducts co-localize with inducible nitric oxide synthase in Alzheimer's disease. Brain Res. 920:32-40
     Abstract: Advanced glycation endproducts (AGEs), protein-bound oxidation products of sugars, have been shown to be involved in the pathophysiological processes of Alzheimer's disease (AD). AGEs induce the expression of various pro-inflammatory cytokines and the inducible nitric oxide synthase (iNOS) leading to a state of oxidative stress. AGE modification and resulting crosslinking of protein deposits such as amyloid plaques may contribute to the oxidative stress occurring in AD. The aim of this study was to immunohistochemically compare the localization of AGEs and beta-amyloid (Abeta) with iNOS in the temporal cortex (Area 22) of normal and AD brains. In aged normal individuals as well as early stage AD brains (i.e. no pathological findings in isocortical areas), a few astrocytes showed co-localization of AGE and iNOS in the upper neuronal layers, compared with no astrocytes detected in young controls. In late AD brains, there was a much denser accumulation of astrocytes co-localized with AGE and iNOS in the deeper and particularly upper neuronal layers. Also, numerous neurons with diffuse AGE but not iNOS reactivity and some AGE and iNOS-positive Microglia were demonstrated, compared with only a few AGE-reactive neurons and no Microglia in controls. Finally, astrocytes co-localized with AGE and iNOS as well as AGE and were found surrounding mature but not diffuse amyloid plaques in the AD brain. Our results show that AGE-positive astrocytes and Microglia in the AD brain express iNOS and support the evidence of an AGE-induced oxidative stress occurring in the vicinity of the characteristic lesions of AD. Hence activation of Microglia and astrocytes by AGEs with subsequent oxidative stress and cytokine release may be an important progression factor in AD

204. Wong A, Dukic-Stefanovic S, Gasic-Milenkovic J, Schinzel R, Wiesinger H, Riederer P, Munch G (2001) Anti-inflammatory antioxidants attenuate the expression of inducible nitric oxide synthase mediated by advanced glycation endproducts in murine Microglia. Eur.J.Neurosci. 14:1961-1967
     Abstract: Advanced glycation endproducts (AGEs) accumulate on long-lived protein deposits including beta-amyloid plaques in Alzheimer's disease (AD). AGE-modified amyloid deposits contain oxidized and nitrated proteins as markers of a chronic neuroinflammatory condition and are surrounded by activated Microglial and astroglial cells. We show in this study that AGEs increase nitric oxide production by induction of the inducible nitric oxide synthase (iNOS) on the mRNA and protein level in the murine Microglial cell line N-11. Membrane permeable antioxidants including oestrogen derivatives (e.g. 17beta-oestradiol) thiol antioxidants (e.g. (R+)-alpha-lipoic acid) and Gingko biloba extract EGb 761, but not phosphodiesterase inhibitors such as propentophylline, prevent the up-regulation of AGE-induced iNOS expression and NO production. These results indicate that oxygen free radicals serve as second messengers in AGE-induced pro-inflammatory signal transduction pathways. As this pharmacological mechanism is not only relevant for Alzheimer's disease, but also for many chronic inflammatory conditions, such membrane-permeable antioxidants could be regarded not only as antioxidant, but also as potent therapeutic anti-inflammatory drugs

205. Wyss-Coray T, Lin C, Yan F, Yu GQ, Rohde M, McConlogue L, Masliah E, Mucke L (2001) TGF-beta1 promotes Microglial amyloid-beta clearance and reduces plaque burden in transgenic mice. Nat.Med. 7:612-618
     Abstract: Abnormal accumulation of the amyloid-beta peptide (Abeta) in the brain appears crucial to pathogenesis in all forms of Alzheimer disease (AD), but the underlying mechanisms in the sporadic forms of AD remain unknown. Transforming growth factor beta1 (TGF-beta1), a key regulator of the brain's responses to injury and inflammation, has been implicated in Abeta deposition in vivo. Here we demonstrate that a modest increase in astroglial TGF-beta1 production in aged transgenic mice expressing the human beta-amyloid precursor protein (hAPP) results in a three-fold reduction in the number of parenchymal amyloid plaques, a 50% reduction in the overall Abeta load in the hippocampus and neocortex, and a decrease in the number of dystrophic neurites. In mice expressing hAPP and TGF-beta1, Abeta accumulated substantially in cerebral blood vessels, but not in parenchymal plaques. In human cases of AD, Abeta immunoreactivity associated with parenchymal plaques was inversely correlated with Abeta in blood vessels and cortical TGF-beta1 mRNA levels. The reduction of parenchymal plaques in hAPP/TGF-beta1 mice was associated with a strong activation of Microglia and an increase in inflammatory mediators. Recombinant TGF-beta1 stimulated Abeta clearance in Microglial cell cultures. These results demonstrate that TGF-beta1 is an important modifier of amyloid deposition in vivo and indicate that TGF-beta1 might promote Microglial processes that inhibit the accumulation of Abeta in the brain parenchyma

206. Yamada M, Itoh Y, Sodeyama N, Suematsu N, Otomo E, Matsushita M, Mizusawa H (2001) Senile dementia of the neurofibrillary tangle type: a comparison with Alzheimer's disease. Dement.Geriatr.Cogn Disord. 12:117-126
     Abstract: A subset of senile dementia, 'senile dementia (SD) of the neurofibrillary tangle (NFT) type' (SD-NFT), is characterized by numerous NFTs in the hippocampal region and absence or scarcity of senile plaques throughout the brain. To elucidate the pathogenesis of SD-NFT in comparison with Alzheimer's disease (AD), we investigated the hippocampal lesions and analyzed the tau gene. The hippocampal regions from 5 patients with SD-NFT were neuropathologically evaluated in comparison with AD and nondemented control subjects. The tau gene was analyzed in 3 patients with SD-NFT. The densities of NFTs in the CA1/subiculum and entorhinal cortex of SD-NFT were significantly higher than those in AD. However, hippocampal atrophy, neuronal and synaptic loss, and astrocytic and Microglial proliferation in SD-NFT were significantly mild compared with AD. There was no significant difference between SD-NFT and AD in the immunoreactivities of NFTs with different anti-tau antibodies. No mutation was found in the tau gene from the SD-NFT patients. Our results indicate that the neurodegenerative process with NFT formation of the hippocampal region in SD-NFT would be different from that in AD

207. Yasojima K, Tourtellotte WW, McGeer EG, McGeer PL (2001) Marked increase in cyclooxygenase-2 in ALS spinal cord: implications for therapy. Neurology 57:952-956
     Abstract: OBJECTIVE: To evaluate the hypothesis that cyclooxygenase-2 (COX-2) is linked to the pathology of ALS by determining whether COX-2 mRNA levels are upregulated in ALS spinal cord. METHODS: Spinal cord from 11 ALS cases and 27 controls consisting of 15 cases of Alzheimer disease (AD), six cases of Parkinson disease (PD), three cases of cerebrovascular disease, and three control cases were analyzed. Total RNA was extracted and reverse transcriptase-PCR analysis performed for the mRNA of COX-2, COX-1, the Microglial marker CD11b, and the housekeeping gene cyclophilin. RESULTS: In ALS compared with non-ALS spinal cord, COX-2 mRNA was upregulated 7.09-fold (p < 0.0001), COX-1 1.14-fold (p = 0.05), and CD11b 1.85-fold (p = 0.0012). COX-2 mRNA levels in AD, PD, cerebrovascular disease, and control cases were each significantly lower than in ALS and were not significantly different from each other. Western blots of the protein products were in general accord with the mRNA data, with COX-2 protein levels being upregulated 3.79-fold compared with non-ALS cases (p = 0.015). CONCLUSIONS: The strong upregulation of COX-2 mRNA in ALS is in accord with studies in the superoxide dismutase transgenic mouse model in which COX-2 upregulation occurs. Taken in conjunction with evidence of a neuroprotective effect of COX-2 inhibitors in certain animal models and in organotypic cultures, the data are supportive of a possible future role for COX-2 inhibitors in the treatment of ALS

208. Akiyama H, Arai T, Kondo H, Tanno E, Haga C, Ikeda K (2000) Cell mediators of inflammation in the Alzheimer disease brain. Alzheimer Dis.Assoc.Disord. 14 Suppl 1:S47-S53
     Abstract: Lesions of Alzheimer disease are associated with low-grade but sustained inflammatory responses. Activated Microglia agglomerate in the center of senile plaques. Reactive astrocytes marginate the amyloid beta-protein (A beta) deposits and extend their processes toward the center of plaques. Both Microglia and astrocytes are known to secrete a wide variety of molecules involved in inflammation and are potential sources of proinflammatory elements in the brain. Dystrophic neurites occur in senile plaques with such glial reactions, suggesting the relevance of inflammatory responses to the neuronal degeneration in Alzheimer disease. Activated glial cells are, therefore, targets of anti-inflammatory therapy of Alzheimer disease. However, evidence also indicates that these cells eliminate A beta from the brain. A beta is produced continuously in both the normal and the AD brain. Under normal conditions, A beta is removed successfully before it accumulates as extracellular amyloid fibrils. Even in Alzheimer disease, a large portion of A beta may be cleared from the brain with a small portion being left and deposited as neurotoxic senile plaques. Both in vivo and in vitro studies showed the effective uptake of A beta by Microglia. Before clinical application, it must be determined whether the treatment that suppresses glial activation and inflammatory responses inhibits A beta removal by glial cells

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

210. Arends YM, Duyckaerts C, Rozemuller JM, Eikelenboom P, Hauw JJ (2000) Microglia, amyloid and dementia in Alzheimer disease. A correlative study. Neurobiol.Aging 21:39-47
     Abstract: To elucidate the role of Microglia in Alzheimer's disease, a clinicopathological study was performed involving 26 cases, the mental status of which had been studied pre mortem by the Blessed test score (BTS). We measured the volume density of CD 68 immunoreactive (IR) Microglia, congophilic plaques and Abeta deposits, and the numerical density of neurofibrillary tangles (NFT) in a sample of Area 9 (middle frontal gyrus). Dementia was significantly correlated only with the volume density of Abeta deposits and the numerical density of NFT. The volume densities of Microglia and congophilic plaques were strongly correlated. With the intellectual status used as a time scale, IR Microglia and amyloid deposits appeared almost simultaneously at an early stage in the pathological cascade and decreased, whereas Abeta and NFT were still accumulating. The intellectual deficit seemed to be more significantly related to the latter two lesions than to the Microglia-amyloid complex, that was visible at an earlier stage (around BTS = 15)

211. Arnold SE, Han LY, Clark CM, Grossman M, Trojanowski JQ (2000) Quantitative neurohistological features of frontotemporal degeneration. Neurobiol.Aging 21:913-919
     Abstract: Frontotemporal degeneration (FTD) is a neurodegenerative condition that has been principally associated with frontal lobe dementia. In this study, we compared neuropathological abnormalities in frontal, hippocampal, and calcarine cortices from patients assigned a diagnosis of FTD, normal elderly and Alzheimer's disease (AD). Densities of Nissl-stained neurons and lesions which were immunolabeled for tau, beta-amyloid (Abeta), alpha- and beta-synuclein, ubiquitin, glial fibrillary acidic protein (GFAP) and CD68 antigen were determined using computer-assisted, non-biased quantitative microscopy. We found that FTD frontal and hippocampal regions exhibited marked neuron loss, abundant ubiquitin-immunoreactive (ir) dystrophic neurites, GFAP-ir astrocytes, and CD68-ir Microglia, while calcarine cortex was spared. No alpha- or beta-synuclein-ir lesions were observed, and neither the density of tau-ir neurofibrillary tangles nor that of Abeta-ir plaques in FTD exceeded normal controls. In addition, there were no neuropathological differences between FTD subjects who presented clinically with a frontal lobe dementia versus an AD-like dementia. These findings indicate that FTD is a category of neurodegnerative dementias with varying clinical presentations that is characterized by the progressive degeneration of select populations of cortical neurons. The molecular neurodegenerative mechanisms that lead to FTD remain to be elucidated

212. Bard F, Cannon C, Barbour R, Burke RL, Games D, Grajeda H, Guido T, Hu K, Huang J, Johnson-Wood K, Khan K, Kholodenko D, Lee M, Lieberburg I, Motter R, Nguyen M, Soriano F, Vasquez N, Weiss K, Welch B, Seubert P, Schenk D, Yednock T (2000) Peripherally administered antibodies against amyloid beta-peptide enter the central nervous system and reduce pathology in a mouse model of Alzheimer disease. Nat.Med. 6:916-919
     Abstract: One hallmark of Alzheimer disease is the accumulation of amyloid beta-peptide in the brain and its deposition as plaques. Mice transgenic for an amyloid beta precursor protein (APP) mini-gene driven by a platelet-derived (PD) growth factor promoter (PDAPP mice), which overexpress one of the disease-linked mutant forms of the human amyloid precursor protein, show many of the pathological features of Alzheimer disease, including extensive deposition of extracellular amyloid plaques, astrocytosis and neuritic dystrophy. Active immunization of PDAPP mice with human amyloid beta-peptide reduces plaque burden and its associated pathologies. Several hypotheses have been proposed regarding the mechanism of this response. Here we report that peripheral administration of antibodies against amyloid beta-peptide, was sufficient to reduce amyloid burden. Despite their relatively modest serum levels, the passively administered antibodies were able to enter the central nervous system, decorate plaques and induce clearance of preexisting amyloid. When examined in an ex vivo assay with sections of PDAPP or Alzheimer disease brain tissue, antibodies against amyloid beta-peptide triggered Microglial cells to clear plaques through Fc receptor-mediated phagocytosis and subsequent peptide degradation. These results indicate that antibodies can cross the blood-brain barrier to act directly in the central nervous system and should be considered as a therapeutic approach for the treatment of Alzheimer disease and other neurological disorders

213. Barger SW, Chavis JA, Drew PD (2000) Dehydroepiandrosterone inhibits Microglial nitric oxide production in a stimulus-specific manner. J.Neurosci.Res. 62:503-509
     Abstract: Dehydroepiandrosterone (DHEA) is a steroid that circulates in abundance in the form of a sulfated reserve (DHEA-S). The levels of DHEA decline with age and further in age-related neuropathologies, including Alzheimer disease. Because of their reported anti-inflammatory effects, we tested the actions of these compounds on Microglia. At concentrations of 3(-9) to 1(-6) M, DHEA and DHEA-S inhibited the production of nitrite and morphological changes stimulated by lipopolysaccharide. DHEA and DHEA-S also inhibited LPS induction of iNOS protein, but neither inhibited LPS-induced iNOS mRNA or the activation of NF-kappaB. These data suggest that the hormone regulates nitrite production through a post-transcriptional mechanism. Interestingly, Microglial nitrite production in response to a secreted form of the beta-amyloid precursor protein (sAPP) was unaffected by DHEA. Another Alzheimer-related factor, amyloid beta-peptide, also stimulated Microglial nitrite production but in a manner dependent on the co-stimulus interferon-gamma. DHEA was found to inhibit only the interferon-gamma component of the Microglial response. These data add to a growing body of evidence for differences in the profiles of mononuclear phagocytes activated by distinct stimuli

214. Bertram L, Blacker D, Mullin K, Keeney D, Jones J, Basu S, Yhu S, McInnis MG, Go RC, Vekrellis K, Selkoe DJ, Saunders AJ, Tanzi RE (2000) Evidence for genetic linkage of Alzheimer's disease to chromosome 10q. Science 290:2302-2303
     Abstract: Recent studies suggest that insulin-degrading enzyme (IDE) in neurons and Microglia degrades Abeta, the principal component of beta-amyloid and one of the neuropathological hallmarks of Alzheimer's disease (AD). We performed parametric and nonparametric linkage analyses of seven genetic markers on chromosome 10q, six of which map near the IDE gene, in 435 multiplex AD families. These analyses revealed significant evidence of linkage for adjacent markers (D10S1671, D10S583, D10S1710, and D10S566), which was most pronounced in late-onset families. Furthermore, we found evidence for allele-specific association between the putative disease locus and marker D10S583, which has recently been located within 195 kilobases of the IDE gene

215. Blain H, Jouzeau JY, Blain A, Terlain B, Trechot P, Touchon J, Netter P, Jeandel C (2000) [Non-steroidal anti-inflammatory drugs with selectivity for cyclooxygenase-2 in Alzheimer's disease. Rationale and perspectives]. Presse Med. 29:267-273
     Abstract: POSSIBLE INFLAMMATORY MECHANISMS: Alzheimer's disease (AD) is a degenerative disease of the brain including possibly inflammatory mechanisms, as illustrated by the presence of activated Microglial cells in the periphery of senile plaques and neurofibrillary tangles and the subsequent release of proinflammatory mediators with neurotoxic potency. RATIONALE FOR NSAID USE: Although not firmly demonstrated, the rationale for the prescription of non steroidal anti-inflammatory drugs (NSAIDS) as neuroprotective agents in AD lies on epidemiological data having shown a reduced risk of developing AD in patients on long-term therapy with NSAIDs (non selective cyclo-oxygenase [COX] inhibitors). RATIONALE FOR THE USE OF SELECTIVE COX-2 INHIBITORS: The rationale for the prescription of selective COX-2 inhibitors as neuroprotective drugs in AD lies on: Epidemiological data having shown a reduced risk of developing AD in patients treated with anti-inflammatory doses of classical NSAIDs (inhibition of COX-1 and COX-2) but not with antithrombotic doses of aspirin (selective inhibition of COX-1), Cellular experiments, Demonstration of a better gastro-intestinal (GI) safety profile with selective COX-2 inhibitors than with classical NSAIDs in short-term studies, allowing a possible long-term use in AD. BEFORE PRESCRIBING: COX-2 may have an ambivalent functionality in the brain since the basal production of prostaglandins through COX-2 may participate in neuronal homeostasis whereas the expression of COX-2 is associated with brain development. Classical NSAIDs are ineffective in reducing the formation of senile plaque and neurofibrillary tangles in AD, which is consistent with an ability to reduce inflammation associated with activation of Microglia but illustrates their failure to suppress the degenerative process. Prophylactic use of selective COX-2 NSAIDs can be considered on the basis of their good GI safety after 6 months of marketing in United States but need to be confirmed for a longer time. CURRENT TRIALS: Clinical studies focusing on both the prevention and the slowing down of early AD are under way with two recently launched selective COX-2 inhibitors, celecoxib and rofecoxib

216. Bornemann KD, Staufenbiel M (2000) Transgenic mouse models of Alzheimer's disease. Ann.N.Y.Acad.Sci. 908:260-266
     Abstract: Alzheimer's disease (AD) pathology is characterized by A beta peptide-containing plaques, neurofibrillary tangles consisting of hyperphosphorylated tau, extensive neuritic degeneration, and distinct neuron loss. We generated several transgenic mouse lines expressing the human amyloid precursor protein (APP751) containing the AD-linked KM670/671NL double mutation (Swedish mutation) under the control of a neuron-specific Thy-1 promoter fragment. In the best APP-expressing line (APP23), compact A beta deposits can be detected at 6 months of age. These plaques dramatically increase with age, are mostly Congo Red positive, and accumulate typical plaque-associated proteins such as heparansulfate proteoglycan and apolipoprotein E. Activated astrocytes and Microglia indicative of inflammatory processes reminiscent of AD accumulate around the deposits. Furthermore, plaques are surrounded by enlarged dystrophic neurites as visualized by neurofilament or Holmes-Luxol staining. Strong staining for acetylcholinesterase activity is found throughout the plaques and is accompanied by local distortion of the cholinergic fiber network. All congophilic plaques contain hyperphosphorylated tau reminiscent of early tau pathology. Modern stereologic methods demonstrate a significant loss of neurons in the hippocampal CA1 region, correlating with an increasing A beta plaque load. Interestingly, APP23 mice develop cerebral amyloid angiopathy in addition to amyloid plaques even though the APP transgene is only expressed in neurons. Crossbreeding of APP23 mice with transgenic mice carrying AD-linked presenilin mutations but not wild-type presenilin resulted in enhanced formation of pathology. In conclusion, our APP transgenic mice present many pathologic features, similar to those observed in AD and therefore offer excellent tools for studying the contribution of A beta to AD pathogenesis

217. Brazil MI, Chung H, Maxfield FR (2000) Effects of incorporation of immunoglobulin G and complement component C1q on uptake and degradation of Alzheimer's disease amyloid fibrils by Microglia. J.Biol.Chem. 275:16941-16947
     Abstract: Microglia are macrophage-like immune system cells found in the brain. They are associated with Alzheimer's Disease plaques, which contain fibrillar beta-amyloid (fAbeta) and other components such as complement proteins. We have shown previously that murine Microglia bind and internalize fAbeta microaggregates via the type A scavenger receptor, but degradation of internalized fAbeta is significantly slower than normal degradation. In this study, we compared internalization by Microglia of fAbeta microaggregates to that of anti-Abeta-antibody-coated fAbeta (IgG-fAbeta) microaggregates and found that the uptake of the latter is increased by about 1.5-fold versus unmodified fAbeta. The endocytic trafficking of IgG-fAbeta is similar to that of fAbeta microaggregates, following an endosomal/lysosomal pathway. We also compared the internalization of fAbeta microaggregates to that of complement protein, C1q-coated fAbeta microaggregates, and found that the levels of uptake are also increased by about 1.5-fold. Rates of degradation of both types of modified fAbeta microaggregates are unchanged compared with unmodified fAbeta microaggregates. We demonstrated by blocking studies that internalization of IgG-fAbeta is mediated by Fc receptors. These data suggest that, in vivo, several different Microglial receptors may play a part in internalizing fAbeta, but the involvement of other receptors may not increase the degradation of fAbeta

218. Calingasan NY, Gibson GE (2000) Vascular endothelium is a site of free radical production and inflammation in areas of neuronal loss in thiamine-deficient brain. Ann.N.Y.Acad.Sci. 903:353-356
     Abstract: Free radical production in vascular endothelial cells and inflammatory responses in perivascular Microglia accompany the selective neuronal death induced by TD. Lipid peroxidation and tyrosine nitration occur in neurons within susceptible areas. Thus, region- and cell-specific oxidative stress contributes to selective neurodegeneration during TD. These data are consistent with the hypothesis that in TD, vascular factors constitute a critical part of a cascade of events leading to increases in blood-brain barrier permeability to nonneuronal proteins and iron, leading to inflammation and oxidative stress. Inflammatory cells may release deleterious compounds or cytokines that exacerbate the oxidative damage to metabolically compromised neurons. Similar mechanisms may operate in the pathophysiology of neurodegenerative diseases in which vascular factors, inflammation and oxidative stress are implicated including AD

219. Cole GM, Ard MD (2000) Influence of lipoproteins on Microglial degradation of Alzheimer's amyloid beta-protein. Microsc.Res.Tech. 50:316-324
     Abstract: Amyloid beta-protein (Abeta), the major component of plaques in Alzheimer's disease, is a small hydrophobic protein that is carried on apolipoprotein E (ApoE)- and ApoJ-containing lipoprotein particles in plasma and cerebrospinal fluid (CSF). Microglia, the scavenger cells of the CNS, take up and degrade Abeta via lipoprotein receptors including scavenger receptors A and B, and possibly via other receptors. Lipoproteins, ApoE, and ApoJ influence the uptake and degradation of Abeta in vitro and in vivo. Differences in ApoE-E4, -E3, and -E2 isoforms with respect to Abeta binding to lipoproteins and delivery to cells, including Microglia, may contribute to the increased risk of Alzheimer's disease for people with an APOE4 genotype and to risk reduction with APOE2

220. Colton CA, Chernyshev ON, Gilbert DL, Vitek MP (2000) Microglial contribution to oxidative stress in Alzheimer's disease. Ann.N.Y.Acad.Sci. 899:292-307
     Abstract: Microglia are the CNS macrophage and are a primary cellular component of plaques in Alzheimer's disease (AD) that may contribute to the oxidative stress associated with chronic neurodegeneration. We now report that superoxide anion production in Microglia or macrophages from 3 different species is increased by long term exposure (24 hours) to A beta peptides. Since A beta competes for the uptake of opsonized latex beads and for the production of superoxide anion by opsonized zymosan, a likely site of action are membrane receptors associated with the uptake of opsonized particles or fibers. The neurotoxic fibrillar peptides A beta (1-42) and human amylin increase radical production whereas a non-toxic, non-fibrillar peptide, rat amylin, does not. We also report that the effect of A beta peptides on superoxide anion production is not associated with a concomitant increase in nitric oxide (NO) production in either human monocyte derived macrophages (MDM) or hamster Microglia from primary cultures. Since NO is known to protect membrane lipids and scavenge superoxide anion, the lack of A beta-mediated induction of NO production in human Microglia and macrophages may be as deleterious as the over-production of superoxide anion induced by chronic exposure to A beta peptides

221. Combs CK, Johnson DE, Karlo JC, Cannady SB, Landreth GE (2000) Inflammatory mechanisms in Alzheimer's disease: inhibition of beta-amyloid-stimulated proinflammatory responses and neurotoxicity by PPARgamma agonists. J.Neurosci. 20:558-567
     Abstract: Alzheimer's disease (AD) is characterized by the extracellular deposition of beta-amyloid fibrils within the brain and the subsequent association and phenotypic activation of Microglial cells associated with the amyloid plaque. The activated Microglia mount a complex local proinflammatory response with the secretion of a diverse range of inflammatory products. Nonsteroidal anti-inflammatory drugs (NSAIDs) are efficacious in reducing the incidence and risk of AD and significantly delaying disease progression. A recently appreciated target of NSAIDs is the ligand-activated nuclear receptor peroxisome proliferator-activated receptor gamma (PPARgamma). PPARgamma is a DNA-binding transcription factor whose transcriptional regulatory actions are activated after agonist binding. We report that NSAIDs, drugs of the thiazolidinedione class, and the natural ligand prostaglandin J2 act as agonists for PPARgamma and inhibit the beta-amyloid-stimulated secretion of proinflammatory products by Microglia and monocytes responsible for neurotoxicity and astrocyte activation. The activation of PPARgamma also arrested the differentiation of monocytes into activated macrophages. PPARgamma agonists were shown to inhibit the beta-amyloid-stimulated expression of the cytokine genes interleukin-6 and tumor necrosis factor alpha. Furthermore, PPARgamma agonists inhibited the expression of cyclooxygenase-2. These data provide direct evidence that PPARgamma plays a critical role in regulating the inflammatory responses of Microglia and monocytes to beta-amyloid. We argue that the efficacy of NSAIDs in the treatment of AD may be a consequence of their actions on PPARgamma rather than on their canonical targets the cyclooxygenases. Importantly, the efficacy of these agents in inhibiting a broad range of inflammatory responses suggests PPARgamma agonists may provide a novel therapeutic approach to AD

222. De Groot CJ, Montagne L, Janssen I, Ravid R, van d, V, Veerhuis R (2000) Isolation and characterization of adult Microglial cells and oligodendrocytes derived from postmortem human brain tissue. Brain Res.Brain Res.Protoc. 5:85-94
     Abstract: The present study provides a detailed description of the simultaneous establishment and immunocytochemical characterization of highly enriched human adult Microglial cell cultures as well as of oligodendrocyte cultures. For this study, brain tissue specimens were collected at autopsy with relatively short postmortem times (3-9 h) from various regions of the CNS of Alzheimer's disease, Pick's disease and non-demented control cases. Although methods to isolate viable glial cells from human adult brain tissue have been described, these human brain specimens were often derived from surgical resections, i.e., in order to treat intractable epilepsy, brain tumors or cardiovascular diseases involving the brain. However, for the study of many neurological disorders, surgical material is not available. Furthermore, for obvious reasons, there is a limit to the number of central nervous system (CNS) regions from which (enough) tissue can be obtained at surgery. The adherent primary Microglial cells, isolated according to the here described procedures consisted of proliferating, phagocytotic cells that expressed various Microglia/macrophage-specific markers as judged by immunocytochemical analysis. Non-adherent cells isolated from the same brain tissue samples expressed oligodendrocyte-specific markers. The current described culture system may provide a valuable tool in studying human CNS biology and disease

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

224. Diez M, Koistinaho J, Kahn K, Games D, Hokfelt T (2000) Neuropeptides in hippocampus and cortex in transgenic mice overexpressing V717F beta-amyloid precursor protein--initial observations. Neuroscience 100:259-286
     Abstract: Immunohistochemistry was used to analyse 18- and 26-month-old transgenic mice overexpressing the human beta-amyloid precursor protein under the platelet-derived growth factor-beta promoter with regard to presence and distribution of neuropeptides. In addition, antisera/antibodies to tyrosine hydroxylase, acetylcholinesterase, amyloid peptide, glial fibrillary acidic protein and Microglial marker OX42 were used. These mice have been reported to exhibit extensive amyloid plaques in the hippocampus and cortex [Masliah et al. (1996) J. Neurosci. 16, 5795-5811].The most pronounced changes were related to neuropeptides, whereas differences between wild-type and transgenic mice were less prominent with regard to tyrosine hydroxylase and acetylcholinesterase. The main findings were of two types; (i) involvement of peptide-containing neurites in amyloid beta-peptide positive plaques, and (ii) more generalized changes in peptide levels in specific layers, neuron populations and/or subregions in the hippocampal formation and ventral cortices. In contrast, the parietal and auditory cortices were comparatively less affected. The peptide immunoreactivities most strongly involved, both in plaques and in the generalized changes, were galanin, neuropeptide Y, cholecystokinin and enkephalin.This study shows that there is considerable variation both with regard to plaque load and peptide expression even among homozygotes of the same age. The most pronounced changes, predominantly increased peptide levels, were observed in two 26-month-old homozygous mice, for example, galanin-, enkephalin- and cholecystokinin-like immunoreactivities in stratum lacunosum moleculare, and galanin, neuropeptide Y, enkephalin and dynorphin in mossy fibers. Many peptides also showed elevated levels in the ventral cortices. However, decreases were also observed. Thus, galanin-like immunoreactivity could not any longer be detected in the diffusely distributed (presumably noradrenergic) fiber network in all hippocampal and cortical layers, and dynorphin-like immunoreactivity was decreased in stratum moleculare, cholecystokinin-like immunoreactivity in mossy fibers and substance P-like immunoreactivity in fibers around granule cells.The significance of generalized peptide changes is at present unclear. For example, the increase in the mainly inhibitory peptides galanin, neuropeptide Y, enkephalin and dynorphin and the decrease in the mainly excitatory peptide cholecystokinin in mossy fibers (and of substance P fibers around granule cells) indicate a shift in balance towards inhibition of the input to the CA3 pyramidal cell layer. Moreover, it may be speculated that the increase in levels of some of the peptides represents a reaction to nerve injury with the aim to counteract, in different ways, the consequences of injury, for example by exerting trophic actions. Further studies will be needed to establish to what extent these changes are typical for Alzheimer mouse models in general or are associated with the V717F mutation and/or the platelet-derived growth factor-beta promoter

225. Eikelenboom P, Rozemuller AJ, Hoozemans JJ, Veerhuis R, Van Gool WA (2000) Neuroinflammation and Alzheimer disease: clinical and therapeutic implications. Alzheimer Dis.Assoc.Disord. 14 Suppl 1:S54-S61
     Abstract: In Alzheimer disease brains, the amyloid plaques are closely associated with a locally induced, nonimmune-mediated, chronic inflammatory response without any apparent influx of leukocytes from the blood. The present findings indicate that in cerebral A beta diseases (Alzheimer disease, Down syndrome, hereditary cerebral hemorrhage with amyloidosis-Dutch type), the clinical symptoms are determined to a great extent by the site of inflammatory response. It was found that the formation of the amyloid-Microglia complex seems to be a relatively early pathogenic event that precedes the process of severe destruction of the neuropil. The idea that inflammation is implicated in Alzheimer pathology has received support from the epidemiologic studies indicating that the use of anti-inflammatory drugs can prevent or retard the Alzheimer disease process. In this contribution, we review the relationship between inflammation and clinical manifestation and the opportunities for anti-inflammatory treatments in Alzheimer disease

226. Emilien G, Beyreuther K, Masters CL, Maloteaux JM (2000) Prospects for pharmacological intervention in Alzheimer disease. Arch.Neurol. 57:454-459
     Abstract: Alzheimer disease (AD) involves neuronal degeneration with impaired cholinergic transmission in the cerebral cortex and hippocampus in areas of the brain particularly associated with memory and higher intellectual functioning. Other neurotransmitter deficits also occur, but the mechanisms underlying the widespread impairment of synaptic functions remain uncertain. Research on the molecular basis of AD has elucidated a pathogenic pathway from which a range of rational pharmacological interventions has emerged. Although at least 3 cholinesterase inhibitors (tacrine hydrochloride, donepezil, and rivastigmine tartrate) are now available and provide patients with modest relief, the most promising strategy involves approaches to retarding, halting, or preventing the formation or accumulation of beta-amyloid (Abeta) plaques. Estrogen is believed to have antioxidant or other anti-Abeta effects, as hormonal replacement therapy in women with menopause is associated with a reduced risk or delayed onset of AD. The association between nonsteroidal anti-inflammatory drugs and a reduced risk of AD has not yet been confirmed, but these agents may protect the brain from the reactive glial and Microglial responses associated with Abeta deposition. Also, recent studies suggested that antioxidants, such as vitamin E taken alone or in combination with selegiline hydrochloride, can delay the progression of AD. Despite these encouraging results, no current therapy has been shown to halt or reverse the underlying disease process. The proof of the principle that anti-Abeta drugs will work in the transgenic models of AD is eagerly awaited with the expectation that they will eventually prove successful in humans

227. Emmerling MR, Watson MD, Raby CA, Spiegel K (2000) The role of complement in Alzheimer's disease pathology. Biochim.Biophys.Acta 1502:158-171
     Abstract: Complement proteins are integral components of amyloid plaques and cerebral vascular amyloid in Alzheimer brains. They can be found at the earliest stages of amyloid deposition and their activation coincides with the clinical expression of Alzheimer's dementia. This review will examine the origins of complement in the brain and the role of beta-amyloid peptide (Abeta) in complement activation in Alzheimer's disease, an event that might serve as a nidus of chronic inflammation. Pharmacology therapies that may serve to inhibit Abeta-mediated complement activation will also be discussed

228. Engelhardt JI, Le WD, Siklos L, Obal I, Boda K, Appel SH (2000) Stereotaxic injection of IgG from patients with Alzheimer disease initiates injury of cholinergic neurons of the basal forebrain. Arch.Neurol. 57:681-686
     Abstract: CONTEXT: The participation of an immune/inflammatory process in the pathomechanism of sporadic Alzheimer disease (AD) has been suggested by evidence for activated Microglia and the potential therapeutic benefit of anti-inflammatory medication. OBJECTIVE: To define a possible role for IgG in the immune/inflammatory process of AD in humans, we assayed the ability of IgG samples from patients with AD to target the injury to cholinergic neurons in rat basal forebrain in vivo. DESIGN: IgG purified from the serum or plasma from patients with AD and patients with other neurological disease who were used as control (DC) patients was injected stereotaxically into the medial septum of adult rats. Four weeks later coronal sections of the whole medial septum-diagonal bands of Broca region were immunostained for choline acetyltransferase (ChAT) to identify cholinergic neuronal cells. SETTING: University medical centers. PATIENTS: Blood samples were collected from 8 patients with probable and definite AD and from 6 age-matched DC patients. MAIN OUTCOME MEASURE: Detection of changes in the number of ChAT immunopositive cell profiles in sections and statistical evaluation. RESULTS: Four weeks after the injections, IgG samples from patients with AD significantly reduced the number of ChAT-immunostained cell profiles in the whole medial septum-diagonal bands of Broca region compared with IgGs from DC patients. Neither DC IgGs nor saline solution significantly decreased the number of ChAT-immunopositive neuronal cell profiles. CONCLUSION: Data document that IgG from patients with AD can target a stereotaxically induced immune/inflammatory injury to cholinergic neurons in the rat basal forebrain in vivo

229. Gilbert DL (2000) Fifty years of radical ideas. Ann.N.Y.Acad.Sci. 899:1-14
     Abstract: My role in the free radical theory of oxygen toxicity is discussed. Rebeca Gerschman and I published several papers on this subject. This sparked my interest in geochemistry and I developed the idea that oxygen was the best qualified biological potential energy source for the following reasons: great abundance, easily accessible, possession of a high thermodynamic potential, and its slow reaction rate. Ionization radiation can be viewed as a catalyst for reactive oxygen species since a killing dose imparts an infinitesimal small amount of energy. Next, Carol A. Colton and I showed that in the mammalian brain that stimulated Microglia produce the superoxide radical anion and its implications in Alzheimer's disease is discussed. More recently, I have become interested in the role of sulfhydryl groups in transcription factors

230. Grimaldi LM, Casadei VM, Ferri C, Veglia F, Licastro F, Annoni G, Biunno I, De Bellis G, Sorbi S, Mariani C, Canal N, Griffin WS, Franceschi M (2000) Association of early-onset Alzheimer's disease with an interleukin-1alpha gene polymorphism. Ann.Neurol. 47:361-365
     Abstract: Overexpression of the pluripotent cytokine interleukin-1 (IL-1) by Microglial cells correlates with formation of neuritic beta-amyloid plaques in Alzheimer's disease (AD). We evaluated polymorphisms in the genes coding for the IL-1alpha, IL-1beta, and IL-1 receptor antagonist cytokines, and tested their association with the occurrence and age at onset of sporadic AD. We found a strong association between the IL-1A T/T genotype and AD onset before 65 years of age (odds ratio, 4.86), with carriers of this genotype showing an onset of disease 9 years earlier than IL-1A C/C carriers. A weaker association with the age at onset was also shown for the IL-1B and IL-1RN genes. These data suggest either a direct effect of the IL-1 gene family, mainly IL-1A, on the clinical onset of AD, or a linkage dysequilibrium with an unknown locus relevant to AD on chromosome 2

231. Halliday G, Robinson SR, Shepherd C, Kril J (2000) Alzheimer's disease and inflammation: a review of cellular and therapeutic mechanisms. Clin.Exp.Pharmacol.Physiol 27:1-8
     Abstract: 1. Of the neurodegenerative diseases that cause dementia, Alzheimer's disease (AD) is the most common. Three major pathologies characterize the disease: senile plaques, neurofibrillary tangles and inflammation. We review the literature on events contributing to the inflammation and the treatments thought to target this pathology. 2. The senile plaques of AD consist primarily of complexes of the beta-amyloid protein. This protein is central to the pathogenesis of the disease. 3. Inflammatory Microglia are consistently associated with senile plaques in AD, although the classic inflammatory response (immunoglobulin and leucocyte infiltration) is absent. beta-Amyloid fragments appear to mediate such inflammatory mechanisms by activating the complement pathway in a similar fashion to immunoglobulin. 4. Epidemiological studies have identified a reduced risk of AD in patients with arthritis and in leprosy patients treated with anti-inflammatory drugs. Longitudinal studies have shown that the consumption of anti-inflammatory medications reduces the risk of AD only in younger patients (< 75 years). 5. There is a considerable body of in vitro evidence indicating that the inflammatory response of Microglial cells is reduced by non-steroidal anti-inflammatory drugs (NSAID). However, no published data are available concerning the effects of these medications on brain pathology in AD. 6. Cyclo-oxygenase 2 enzyme is constitutively expressed in neurons and is up-regulated in degenerative brain regions in AD. Non-steroidal anti-inflammatory drugs may reduce this expression. 7. Platelets are a source of beta-amyloid and increased platelet activation and increased circulating beta-amyloid have been identified in AD. Anti-platelet medication (including NSAID) would prevent such activation and its potentially harmful consequences. 8. Increased levels of luminal beta-amyloid permeabilizes the blood-brain barrier (BBB) and increases vasoconstriction of arterial vessels, paralleling the alterations observed with infection and inflammation. Cerebral amyloidosis is highly prevalent in AD, compromising the BBB and vasoactivity. Anti-inflammatory medications may alleviate these problems

232. Heemels MT (2000) Alzheimer's disease. Plaque removers and shakers. Nature 406:465

233. Hull M, Lieb K, Fiebich BL (2000) Anti-inflammatory drugs: a hope for Alzheimer's disease? Expert.Opin.Investig.Drugs 9:671-683
     Abstract: Human brain cells are capable of initiating and amplifying a brain specific inflammatory response involving the synthesis of cytokines, acute-phase proteins, complement proteins, prostaglandins and oxygen radicals. In Alzheimer's disease (AD), all signs of an inflammatory Microglial and astroglial activation are present inside and outside amyloid depositions and along axons of neurones with neurofibrillary tangles. Cell culture and animal models suggest a bidirectional relationship between inflammatory activation of glial cells and the deposition of amyloid. Although it remains unclear which of the different pathophysiological processes in AD may be the driving force in an individual case, the inflammatory activation may increase the speed of cognitive decline. Epidemiological studies point to a reduced risk of AD among users of anti-inflammatory drugs. Therefore, anti-inflammatory drugs have become the focus of several new treatment strategies. A clinical trial with the non-steroidal anti-inflammatory drug (NSAID) indomethacin showed promising results, while a clinical trial with steroids did not show a beneficial effect. Further trials with NSAIDs such as unselective cyclooxygenase (COX) and selective cyclooxygenase-2 (COX-2) inhibitors are on their way. COX inhibitors may not only act on Microglial and astroglial cells but also reduce neuronal prostaglandin production. New data suggest that prostaglandins enhance neurotoxicity or induce pro-inflammatory cytokine synthesis in astroglial cells. Amongst these promising new strategies to reduce Microglial or monocyte activation, interfering with intracellular pathways has been shown to be effective in various cell culture and animal models but clinical studies have not yet been performed

234. Hull MH, Fiebich BL, Lieb K (2000) Strategies to delay the onset of Alzheimer's disease. EXS 89:211-225
     Abstract: Several processes are implicated in the neuropathology of Alzheimer's disease (AD), such as the deposition of amyloid, the formation of paired helical filaments and the proinflammatory activation of Microglial and astroglial cells. Proinflammatory activation of glial cells has been a focus of research for a mere ten years now. However, the availability of and broad experience with anti-inflammatory drugs has led to several ongoing clinical trials to verify the capacity of anti-inflammatory drugs to ameliorate the deterioration in AD. The enzymatic cleavage of the amyloid-precursor-protein or the hyperphosphorylation of tau as well as the subsequent aggregation of the resulting products are further targets for drugs intended to delay the neuropathological destruction observed in AD

235. Jellinger KA, Stadelmann C (2000) Mechanisms of cell death in neurodegenerative disorders. J.Neural Transm.Suppl 59:95-114
     Abstract: OBJECTIVE: Progressive cell loss in specific neuronal populations is the prominent pathological hallmark of neurodegenerative diseases, but its molecular basis remains unresolved. Apoptotic cell death has been implicated as a general mechanism in Alzheimer disease (AD) and other neurodegenerative disorders. However, DNA fragmention in neurons is too frequent to account for the continuous loss in these slowly progressive diseases. MATERIAL AND METHODS: In 9 cases of morphologically confirmed AD (CERAD criteria, Braak stages 5 or 6), 5 cases of Parkinson disease (PD) and 3 cases each of Dementia with Lewy bodies (DLB), Progressive Supranuclear Palsy (PSP), and Multiple System Atrophy (MSA), and 7 age-matched controls, the TUNEL method was used to detect DNA fragmentation, and immunohistochemistry for an array of apoptosis-related proteins (ARP), protooncogenes, and activated caspase-3 were performed. RESULTS: In AD, a considerable number of hippocampal neurons showed DNA fragmentation with a 3 to 5.7 fold increase related to neurofibrillary tangles and amyloid deposits, but only exceptional neurons displayed apoptotic morphology (1 in 1100-5000) and cytoplasmic immunoreactivity for ARPs and activated caspase-3 (1 in 2600 to 5650 hippocampal neurons), whereas no neurons were labeled in age-matched controls. Caspase-3 immunoreactivity was seen in granules of granulovacuolar degeneration, only rarely colocalized with tau-immunoreactivity. In PD, DLB, and MSA, TUNEL positivity and expression of ARPs or activated caspase-3 was only seen in Microglia, rare astrocytes and in oligodendroglia with cytoplasmic inclusions in MSA, but not in nigral or other neurons with or without Lewy bodies. In PSP, only single neurons but oligodendrocytes, some with tau deposits, in brainstem tegmentum and pontine nuclei were TUNEL-positive and expressed both ARPs and activated caspase-3. CONCLUSIONS: These data provide evidence for extremely rare apoptotic neuronal death in AD compatible with the progression of neuronal degeneration in this chronic disease. In other neurodegenerative disorders, apoptosis mainly involves Microglia and oligodendroglia, while alternative mechanisms of neuronal death may occur. Susceptible cell populations in a proapoptotic environment show increased vulnerability towards metabolic and other pathogenic factors, with autophagy as a possible protective mechanism in early stages of programmed cell death. The intracellular cascade leading to cell death still awaits elucidation

236. Jellinger KA, Stadelmann CH (2000) The enigma of cell death in neurodegenerative disorders. J.Neural Transm.Suppl21-36
     Abstract: Progressive cell loss in specific neuronal populations is the pathological hallmark of neurodegenerative diseases, but its mechanisms remain unresolved. Apoptotic cell death has been implicated as a major mechanism in Alzheimer disease (AD), Parkinson disease (PD) and other neurodegenerative disorders. However, DNA fragmentation in human brain as a sign of neuronal cell injury is too frequent to account for the continuous loss in these slowly progressive diseases. In a series of autopsy confirmed cases of AD, PD, related disorders, and age-matched controls, DNA fragmentation using the TUNEL method, an array of apoptosis-related proteins (ARP), proto-oncogenes, and activated caspase-3, the key enzyme of late-stage apoptosis, were examined. In AD, a considerable number of hippocampal neurons and glial cells showed DNA fragmentation with a 3- to 6-fold increase related to neurofibrillary tangles and amyloid deposits, but only 1 in 2.600 to 5.600 neurons displayed apoptotic morphology and cytoplasmic immunoreactivity for activated caspase-3, whereas no neurons were labeled in age-matched controls. caspase-3 immunoreactivity was seen in granules of cells with granulovacuolar degeneration, in around 25% co-localized with early cytoplasmic deposition of tau-protein. In progressive supranuclear palsy, only single neurons and several oligodendrocytes in brainstem, some with tau-deposits, were TUNEL-positive and expressed both ARPs and activated caspase-3. In PD, dementia with Lewy bodies, multisystem atrophy (MSA), and corticobasal degeneration, TUNEL-positivity and expression of ARPs or activated caspase-3 were only seen in Microglia and oligodendrocytes with cytoplasmic inclusions, but not in neurons. These data provide evidence for extremely rare apoptotic neuronal death in AD and PSP compatible with the progression of neuronal degeneration in these chronic diseases. Apoptosis mainly involves reactive Microglia and oligodendroglia, the latter often involved by deposits of insoluble fibrillary proteins, while alternative mechanisms of neuronal death may occur. Susceptible cell populations in a proapoptotic environment show increased vulnerability towards metabolic or other noxious factors, with autophagy as a possible protective mechanism in early stages of programmed cell death. The intracellular cascade leading to cell death still awaits elucidation

237. Kimura T, Yamamoto H, Takamatsu J, Yuzuriha T, Miyamoto E, Miyakawa T (2000) Phosphorylation of MARCKS in Alzheimer disease brains. Neuroreport 11:869-873
     Abstract: Activation of the amyloid beta-protein precursor, secretary pathway through alpha-secretase has been reported to increase the secretion of neuroprotective amyloid precursor protein and preclude the formation of amyloid beta-protein. Activation of protein kinase C has been shown to accelerate this secretory pathway. These results prompted us to focus on a potential links between protein kinase C and the amyloid beta-protein-related pathology of Alzheimer disease (AD). Although protein kinase C is reported to occur in senile plaques, its catalytic activity has not been investigated. As the phosphorylation of myristoylated alanine-rich C kinase substrate (MARCKS) has been used as a marker for activation of protein kinase C in vivo, we examined its phosphorylation in brain tissues obtained from seven AD patients and five non-demented subjects using an antibody that specifically recognized MARCKS phosphorylated by protein kinase C. Phosphorylation of MARCKS in cortical neurons in AD brains was weaker than that in control brains. Interestingly, however, phosphorylation of MARCKS was detected in Microglia and dystrophic neurites within neuritic plaques, a mature form of amyloid beta-protein deposits. These results suggest that protein kinase C alteration is associated with AD pathology and that protein kinase C is activated in Microglia and dystrophic neurites by amyloid beta-protein in AD brains

238. Lee CK, Weindruch R, Prolla TA (2000) Gene-expression profile of the ageing brain in mice. Nat.Genet. 25:294-297
     Abstract: Ageing of the brain leads to impairments in cognitive and motor skills, and is the major risk factor for several common neurological disorders such as Alzheimer disease (AD) and Parkinson disease (PD). Recent studies suggest that normal brain ageing is associated with subtle morphological and functional alterations in specific neuronal circuits, as opposed to large-scale neuronal loss. In fact, ageing of the central nervous system in diverse mammalian species shares many features, such as atrophy of pyramidal neurons, synaptic atrophy, decrease of striatal dopamine receptors, accumulation of fluorescent pigments, cytoskeletal abnormalities, and reactive astrocytes and Microglia. To provide the first global analysis of brain ageing at the molecular level, we used oligonucleotide arrays representing 6,347 genes to determine the gene-expression profile of the ageing neocortex and cerebellum in mice. Ageing resulted in a gene-expression profile indicative of an inflammatory response, oxidative stress and reduced neurotrophic support in both brain regions. At the transcriptional level, brain ageing in mice displays parallels with human neurodegenerative disorders. Caloric restriction, which retards the ageing process in mammals, selectively attenuated the age-associated induction of genes encoding inflammatory and stress responses

239. Li Y, Liu L, Kang J, Sheng JG, Barger SW, Mrak RE, Griffin WS (2000) Neuronal-glial interactions mediated by interleukin-1 enhance neuronal acetylcholinesterase activity and mRNA expression. J.Neurosci. 20:149-155
     Abstract: Cholinergic dysfunction in Alzheimer's disease has been attributed to stress-induced increases in acetylcholinesterase (AChE) activity. Interleukin-1 (IL-1) is overexpressed in Alzheimer's disease, and stress-related changes in long-term potentiation, an ACh-related cerebral function, are triggered by interleukin-1. Microglial cultures (N9) synthesized and released IL-1 in response to conditioned media obtained from glutamate-treated primary neuron cultures or PC12 cells. This conditioned media contained elevated levels of secreted beta-amyloid precursor protein (sAPP). Naive PC12 cells cocultured with stimulated N9 cultures showed increased AChE activity and mRNA expression. These effects on AChE expression and activity could be blocked by either preincubating the glutamate-treated PC12 supernatants with anti-sAPP antibodies or preincubating naive PC12 cells with IL-1 receptor antagonist. These findings were confirmed in vivo; IL-1-containing pellets implanted into rat cortex also increased AChE mRNA levels. Neuronal stress in Alzheimer's disease may induce increases in AChE expression and activity through a molecular cascade that is mediated by sAPP-induced Microglial activation and consequent overexpression of IL-1

240. Liberski PP, Ironside J, McCardle L, Sherring A (2000) Ultrastructural analysis of the florid plaque in variant Creutzfeldt-Jakob disease. Folia Neuropathol. 38:167-170
     Abstract: We report here the first description of florid plaques--the hallmark of variant Creutzfeldt-Jakob disease (vCJD). These plaques are composed of broad bundles of amyloid, are highly neuritic and exhibited astrocytes and Microglial cells. Collectively, they are more similar to neuritic plaques of Alzheimer's disease than to kuru plaques of kuru--Creutzfeldt-Jakob disease--Gerstmann-Straussler-Sheinker disease

241. Lim GP, Yang F, Chu T, Chen P, Beech W, Teter B, Tran T, Ubeda O, Ashe KH, Frautschy SA, Cole GM (2000) Ibuprofen suppresses plaque pathology and inflammation in a mouse model for Alzheimer's disease. J.Neurosci. 20:5709-5714
     Abstract: The brain in Alzheimer's disease (AD) shows a chronic inflammatory response characterized by activated glial cells and increased expression of cytokines and complement factors surrounding amyloid deposits. Several epidemiological studies have demonstrated a reduced risk for AD in patients using nonsteroidal anti-inflammatory drugs (NSAIDs), prompting further inquiries about how NSAIDs might influence the development of AD pathology and inflammation in the CNS. We tested the impact of chronic orally administered ibuprofen, the most commonly used NSAID, in a transgenic model of AD displaying widespread Microglial activation, age-related amyloid deposits, and dystrophic neurites. These mice were created by overexpressing a variant of the amyloid precursor protein found in familial AD. Transgene-positive (Tg+) and negative (Tg-) mice began receiving chow containing 375 ppm ibuprofen at 10 months of age, when amyloid plaques first appear, and were fed continuously for 6 months. This treatment produced significant reductions in final interleukin-1beta and glial fibrillary acidic protein levels, as well as a significant diminution in the ultimate number and total area of beta-amyloid deposits. Reductions in amyloid deposition were supported by ELISA measurements showing significantly decreased SDS-insoluble Abeta. Ibuprofen also decreased the numbers of ubiquitin-labeled dystrophic neurites and the percentage area per plaque of anti-phosphotyrosine-labeled Microglia. Thus, the anti-inflammatory drug ibuprofen, which has been associated with reduced AD risk in human epidemiological studies, can significantly delay some forms of AD pathology, including amyloid deposition, when administered early in the disease course of a transgenic mouse model of AD

242. Lorton D, Schaller J, Lala A, De Nardin E (2000) Chemotactic-like receptors and Abeta peptide induced responses in Alzheimer's disease. Neurobiol.Aging 21:463-473
     Abstract: Evidence suggests that beta-amyloid (Abeta) has chemokine-like properties and may act through formyl chemotactic receptors (FPR) to induce pathophysiologically important functional changes in Alzheimer's disease (AD) Microglia. We have shown that Abeta 1-42, fibrillar Abeta 1-40, and Abeta 25-35 potentiate the release of interleukin-1beta (IL-1beta) from LPS activated human THP-1 monocytes [26] and LPS primed rat Microglia. Moreover, Abeta-stimulated IL-1beta secretion seems to be receptor mediated because it is calcium dependent and requires activation of specific G-proteins [27]. Thus, we have evaluated the ability of Abeta 1-42 to mimic formyl chemotactic peptides in stimulating IL-1beta release from THP-1 monocytes. Several of the formyl chemotactic peptides and Abeta 1-42 significantly enhanced IL-1beta production in THP-1 monocytes. In contrast, a formyl chemotactic receptor antagonist inhibited Abeta 1-42-induced IL-1beta release from both human THP-1 monocytes and primary rat Microglia. Further, primary rat Microglia grown in culture expressed FPR as demonstrated by immunocytochemistry. Given the multiple pathophysiologic roles IL-1beta may play in AD, agents that block Abeta interactions with formyl chemotactic receptors on Microglia might be important antiinflammatory therapeutic targets

243. Lukiw WJ, Bazan NG (2000) Neuroinflammatory signaling upregulation in Alzheimer's disease. Neurochem.Res. 25:1173-1184
     Abstract: Alzheimer's disease (AD) is a progressive, neurodestructive process of the human neocortex, characterized by the deterioration of memory and higher cognitive function. A progressive and irreversible brain disorder, AD is characterized by three major pathogenic episodes involving (a) an aberrant processing and deposition of beta-amyloid precursor protein (betaAPP) to form neurotoxic beta-amyloid (betaA) peptides and an aggregated insoluble polymer of betaA that forms the senile plaque, (b) the establishment of intraneuronal neuritic tau pathology yielding widespread deposits of agyrophilic neurofibrillary tangles (NFT) and (c) the initiation and proliferation of a brain-specific inflammatory response. These three seemingly disperse attributes of AD etiopathogenesis are linked by the fact that proinflammatory Microglia, reactive astrocytes and their associated cytokines and chemokines are associated with the biology of the microtubule associated protein tau, betaA speciation and aggregation. Missense mutations in the presenilin genes PS1 and PS2, implicated in early onset familial AD, cause abnormal betaAPP processing with resultant overproduction of betaA42 and related neurotoxic peptides. Specific betaA fragments such as betaA42 can further potentiate proinflammatory mechanisms. Expression of the inducible oxidoreductase cyclooxygenase-2 and cytosolic phospholipase A2 (cPLA2) are strongly activated during cerebral ischemia and trauma, epilepsy and AD, indicating the induction of proinflammatory gene pathways as a response to brain injury. Neurotoxic metals such as aluminum and zinc, both implicated in AD etiopathogenesis, and arachidonic acid, a major metabolite of brain cPLA2 activity, each polymerize hyperphosphorylated tau to form NFT-like bundles. Further, epidemiological and longitudinal studies have identified a reduced risk for AD in patients (<70 yrs) previously treated with non-steroidal anti-inflammatory drugs for non-CNS afflictions that include arthritis. This review will focus on the interrelationships between the mechanisms of PS1, PS2 and betaAPP gene expression, tau and betaA deposition and the induction, regulation and proliferation in AD of the neuroinflammatory response. Novel therapeutic interventions in AD are discussed

244. Mackenzie IR (2000) Anti-inflammatory drugs and Alzheimer-type pathology in aging. Neurology 54:732-734
     Abstract: Anti-inflammatory drugs have been suggested as a treatment for AD. The authors examined the AD-type pathology in postmortem brain tissue from elderly nondemented individuals who were chronically exposed to anti-inflammatory drugs. The results suggest that 1) these drugs do not affect the formation of either senile plaques or neurofibrillary tangles and 2) nonsteroidal anti-inflammatory drugs may be more effective than steroids in treating AD because of their ability to suppress the Microglial activation associated with senile plaques

245. Mackenzie IR (2000) Activated Microglia in dementia with Lewy bodies. Neurology 55:132-134
     Abstract: To investigate the role of cerebral inflammation in dementia with Lewy bodies (DLB), activated Microglial cells were quantified in postmortem brain tissue. Patients with pure DLB (LB but no AD pathology) had significantly greater numbers of cells than nondemented control subjects, but fewer than patients with either pure AD or DLB combined with AD. There was a positive correlation between the numbers of activated Microglia and LB in different brain regions. This study demonstrates the presence of significant inflammation in DLB, even in the absence of AD pathology

246. Marzolo MP, von Bernhardi R, Bu G, Inestrosa NC (2000) Expression of alpha(2)-macroglobulin receptor/low density lipoprotein receptor-related protein (LRP) in rat Microglial cells. J.Neurosci.Res. 60:401-411
     Abstract: Low density lipoprotein receptor-related protein (LRP) participates in the uptake and degradation of several ligands implicated in neuronal pathophysiology including apolipoprotein E (apoE), activated alpha(2) -macroglobulin (alpha(2)M*) and beta-amyloid precursor protein (APP). The receptor is expressed in a variety of tissues. In the brain LRP is present in pyramidal-type neurons in cortical and hippocampal regions and in astrocytes that are activated as a result of injury or neoplasmic transformation. As LRP is expressed in the monocyte/macrophage cell system, we were interested in examining whether LRP is expressed in Microglia. We isolated glial cells from the brain of neonatal rats and LRP was immunodetected both in Microglial cells and in astrocytes expressing glial fibrillar acidic protein (GFAP). Microglial cells were able to bind and internalize LRP-specific ligand, alpha(2)M*. The internalization was inhibitable by RAP, with a Kd of 1.7 nM. The expression of LRP was up-regulated by dexamethasone, and down-regulated by lipopolysaccharide (LPS), gamma interferon (IFN-gamma) or a combination of both. LRP was less sensitive to dexamethasone in activated astrocytes than in Microglia. We provided the first analysis of LRP expression and regulation in Microglia. Our results open the possibility that Microglial cells could be related to the participation of LRP and its ligands in different pathophysiological states in brain

247. Masliah E, Rockenstein E (2000) Genetically altered transgenic models of Alzheimer's disease. J.Neural Transm.Suppl 59:175-183
     Abstract: Abnormal processing and aggregation of synaptic proteins might play an important role in the pathogenesis of neurodegenerative disorders. Among them, amyloid precursor protein (APP) has been clearly associated with Alzheimer's disease (AD) and various transgenic (tg) animal models have been developed where mutant APP is overexpressed under the regulatory control of neuronal promoters. These studies have shown that AD-like pathology (namely plaques and synapse damage) begins to develop at 6-8 months of age in mice expressing human APP under Thy1, platelet-derived growth factor (B-chain) or protease-resistant prion protein promoters, provided that levels of APP are higher than 5-7 fold of endogenous levels. None of these models have shown the presence of tangles; however, tau-immunoreactive neurites in plaques and astroglial/Microglial activation are observed after 12 months of age. Neuronal loss and alterations of synaptic function and connectivity are found in the CA1 region in the PDAPP tg mice lacking the Swiss Webster background. Co-expression of other genes associated with AD modify this phenotype, for example, mutant presenilin 1 accelerates the onset of plaque formation, transforming growth factor beta enhances vascular amyloidosis, and apolipoprotein E decreases amyloid deposition. In conclusion, tg mice which are capable of mimicking some aspects of AD (provided that high enough levels of expression are achieved) can potentially be used to test novel drugs for the treatment of neurodegenerative disorders

248. Masumura M, Hata R, Nishimura I, Uetsuki T, Sawada T, Yoshikawa K (2000) Caspase-3 activation and inflammatory responses in rat hippocampus inoculated with a recombinant adenovirus expressing the Alzheimer amyloid precursor protein. Brain Res.Mol.Brain Res. 80:219-227
     Abstract: To elucidate the mechanism of neuronal death in Alzheimer's disease, we investigated the effects of overexpression of wild-type Alzheimer amyloid precursor protein (APP) on neuronal cells and glial cells in vivo. When an APP695-expressing adenovirus was injected into the dorsal hippocampal region, a number of neurons in remote areas were positively stained with anti-APP monoclonal antibody, and underwent severe degeneration from 3 to 7 days after viral inoculation. Most degenerating neurons were immunopositive with both APP and activated caspase-3, but some neurons that expressed activated caspase-3 were not expressing APP from 7 to 14 days after virus injection. In the neighborhood of the degenerating neurons, activated Microglia/macrophages, which were identified by the phenotypic marker C3bi receptor (CD11b/c; OX-42), were observed, and some of them appeared to phagocytose the caspase-3-immunopositive degenerating neurons. In addition to Microglia/macrophages, infiltrating leukocytes expressing CD45 or CD4 were also detected. These results suggest that the increased accumulation of APP induced not only caspase-3-mediated death machinery, but also inflammatory responses including Microglial activation. These inflammatory responses might cause further neurodegeneration through the alternative pathway that might activate the caspase-3-mediated death machinery without APP expression

249. Matsumoto A, Itoh K, Matsumoto R (2000) A novel carboxypeptidase B that processes native beta-amyloid precursor protein is present in human hippocampus. Eur.J.Neurosci. 12:227-238
     Abstract: The processing of beta-amyloid precursor protein (APP) and generation of beta-amyloid (Abeta) are associated with the pathophysiology of Alzheimer's disease (AD). As the proteases responsible for the process in the human brain have yet to be clarified, we have searched for activities capable of cleaving native brain APP in the human hippocampus. A 40-kDa protein with proteolytic activity that degrades native brain APP in vitro was purified and characterized; molecular analysis identified it as a novel protease belonging to the carboxypeptidase B (CPB) family. PC12 cells overexpressing the cDNA encoding this protease generate a major 12-kDa beta-amyloid-bearing peptide in cytosol, a peptide which has also been detected in a cell-free system using purified brain APP as substrate. Although the protease is homologous to plasma CPB synthesized in liver, it has specific domains such as C-terminal 14 amino acid residues. Western analysis, cDNA-cloning process and Northern analysis suggested a brain-specific expression of this protease. An immunohistochemical study showed that the protease is expressed in various neuronal perikarya, including those of pyramidal neurons of the hippocampus and ependymal-choroid plexus cells, and in a portion of the Microglia of normal brains. In brains of patients with sporadic AD, there is decreased neuronal expression of the protease, and clusters of Microglia with protease immunoreactivity associated with its extracellular deposition are detected. These findings suggest that brain CPB has a physiological function in APP processing and may have significance in AD pathophysiology

250. McGeer PL, McGeer EG, Yasojima K (2000) Alzheimer disease and neuroinflammation. J.Neural Transm.Suppl 59:53-57
     Abstract: It is now generally accepted that the lesions of Alzheimer disease (AD) are associated with a host of inflammatory molecules, including complement proteins, as well as with many activated Microglia. Most inflammatory components are synthesized by brain cells. In order to estimate the intensity of the inflammatory reaction, we have measured the levels of the mRNAs for complement proteins, two complement regulators (CD59 and C1 inhibitors), an acute phase reactant (C-reactive protein, CRP) and two Microglial markers, (HLA-DR and CD11b), in normal and AD brain. The mRNAs for inflammatory mediators are markedly upregulated in AD tissue while those of the complement inhibitors are almost unchanged. The upregulations for CRP and CD11b in AD hippocampus are comparable to those in osteoarthritic joints. This lends further support to the hypothesis that chronic inflammation may be causing neuronal death in AD

251. McGeer PL, McGeer EG (2000) Autotoxicity and Alzheimer disease. Arch.Neurol. 57:789-790
     Abstract: I mmunological responses are considered to be either humoral, resulting from cloning of B lymphocytes, or cell mediated, resulting from cloning of T lymphocytes. Autoimmune diseases occur when the cloned products attack host tissue. Inflammation is considered a nonspecific response to injury, characterized by exudation of serum into damaged tissue, and identified by the cardinal signs of rubor, calor, dolor, and tumor. However, these classic mechanisms do not fit pathological observations of Alzheimer disease (AD)-affected brain tissue. Although many of the components prominently associated with peripheral immunological and inflammatory states are present in AD lesions, there are no identifiable B lymphocytes or antibodies, and T cells are sparse. Furthermore, the blood-brain barrier is intact, excluding exudation of exogenous serum proteins. Although "neuroinflammation" is the term commonly used to describe the pathological changes, it fails to define adequately the process that is taking place. The reaction is neither a nonspecific response to injury, as classically implied for inflammatory reactions, nor an autoimmune reaction, despite the directed attack against plaques and extracellular tangles. It is most appropriately defined as an innate immunoreaction. The fact that such a reaction can be mounted by brain, an organ frequently described as being immunologically privileged, suggests that a reevaluation is required of the dimensions of the innate immune system, including how it operates at the tissue level. The innate immune system is primitive, while the adaptive immune system, which is directed by peripheral immune organs, is an invention of vertebrates. Even in vertebrates, however, the innate immune system is the first line of defense. Much more needs to be learned about the operation of the innate immune system in health and disease. Arch Neurol. 2000

252. Mehlhorn G, Hollborn M, Schliebs R (2000) Induction of cytokines in glial cells surrounding cortical beta-amyloid plaques in transgenic Tg2576 mice with Alzheimer pathology. Int.J.Dev.Neurosci. 18:423-431
     Abstract: beta-Amyloid plaque deposition observed in brains from Alzheimer patients, might function as immune stimulus for glial/macrophages activation, which is supported by observations of activated Microglia expressing interleukin (IL)-1beta and elevated IL-6 immunoreactivity in close proximity to amyloid plaques. To elucidate the mechanisms involved in beta-amyloid-mediated inflammation, transgenic mice (Tg2576) expressing high levels of the Swedish double mutation of human amyloid precursor protein and progressively developing typical beta-amyloid plaques in cortical brain regions including gliosis and astrocytosis, were examined for the expression pattern of a number of cytokines.Using ribonuclease protection assay, interleukin (IL)-1alpha,-beta, IL-1 receptor antagonist, IL-6, IL-10, IL-12, IL-18, interferon-gamma, and macrophage migration inhibitory factor (MIF) mRNA were not induced in a number of cortical areas of Tg2576 mice regardless of the postnatal ages studied ranging between 2 and 13 months. Using immunocytochemistry for IL-1alpha,beta, IL-6, tumor necrosis factor (TNF)-alpha, and macrophage chemotactic protein (MCP)-1, only IL-1beta was found to be induced in reactive astrocytes surrounding beta-amyloid deposits detected in 14-month-old Tg2576 mice. Using non-radioactive in situ hybridization glial fibrillary acidic protein (GFAP) mRNA was detected to be expressed by reactive astrocytes in close proximity to beta-amyloid plaques. The local immune response detected around cortical beta-amyloid deposits in transgenic Tg2576 mouse brain is seemingly different to that observed in brains from Alzheimer patients but may represent an initial event of chronic neuroinflammation at later stages of the disease

253. Morgan TE, Rozovsky I, Sarkar DK, Young-Chan CS, Nichols NR, Laping NJ, Finch CE (2000) Transforming growth factor-beta1 induces transforming growth factor-beta1 and transforming growth factor-beta receptor messenger RNAs and reduces complement C1qB messenger RNA in rat brain Microglia. Neuroscience 101:313-321
     Abstract: Transforming growth factor-beta1 is a multifunctional peptide with increased expression during Alzheimer's disease and other neurodegenerative conditions which involve inflammatory mechanisms. We examined the autoregulation of transforming growth factor-beta1 and transforming growth factor-beta receptors and the effects of transforming growth factor-beta1 on complement C1q in brains of adult Fischer 344 male rats and in primary glial cultures. Perforant path transection by entorhinal cortex lesioning was used as a model for the hippocampal deafferentation of Alzheimer's disease. In the hippocampus ipsilateral to the lesion, transforming growth factor-beta1 peptide was increased >100-fold; the messenger RNAs encoding transforming growth factor-beta1, transforming growth factor-beta type I and type II receptors were also increased, but to a smaller degree. In this acute lesion paradigm, Microglia are the main cell type containing transforming growth factor-beta1, transforming growth factor-beta type I and II receptor messenger RNAs, shown by immunocytochemistry in combination with in situ hybridization. Autoregulation of the transforming growth factor-beta1 system was examined by intraventricular infusion of transforming growth factor-beta1 peptide, which increased hippocampal transforming growth factor-beta1 messenger RNA levels in a dose-dependent fashion. Similarly, transforming growth factor-beta1 increased levels of transforming growth factor-beta1 messenger RNA and transforming growth factor-beta type II receptor messenger RNA (IC(50), 5pM) and increased release of transforming growth factor-beta1 peptide from primary Microglia cultures. Interactions of transforming growth factor-beta1 with complement system gene expression are also indicated, because transforming growth factor-beta1 decreased C1qB messenger RNA in the cortex and hippocampus, after intraventricular infusion, and in cultured glia. These indications of autocrine regulation of transforming growth factor-beta1 in the rodent brain support a major role of Microglia in neural activities of transforming growth factor-beta1 and give a new link between transforming growth factor-beta1 and the complement system. The auto-induction of the transforming growth factor-beta1 system has implications for transgenic mice that overexpress transforming growth factor-beta1 in brain cells and for its potential role in amyloidogenesis

254. Murphy GM, Jr., Zhao F, Yang L, Cordell B (2000) Expression of macrophage colony-stimulating factor receptor is increased in the AbetaPP(V717F) transgenic mouse model of Alzheimer's disease. Am.J.Pathol. 157:895-904
     Abstract: Inflammation is an important neuropathological change in Alzheimer's disease (AD). However, the pathophysiological factors that initiate and maintain the inflammatory response in AD are unknown. We examined AbetaPP(V717F) transgenic mice, which show numerous brain amyloid-beta (Abeta) deposits, for expression of the macrophage colony-stimulating factor (M-CSF) and its receptor (M-CSFR). M-CSF is increased in the brain in AD and dramatically augments the effects of Abeta on cultured Microglia. AbetaPP(V717F) animals 12 months of age showed large numbers of Microglia strongly labeled with an M-CSFR antibody near Abeta deposits. M-CSFR mRNA and protein levels were also increased in brain homogenates from AbetaPP(V717F) animals. Dystrophic neurites and astroglia showed no M-CSFR labeling in the transgenic animals. A M-CSF antibody decorated neuritic structures near hippocampal Abeta deposits in transgenic animals. M-CSF mRNA was also increased in AbetaPP(V717F) animals in comparison with wild-type controls. Simultaneous overexpression of M-CSFR and its ligand in AbetaPP(V717F) animals could result in augmentation of Abeta-induced activation of Microglia. Because chronic activation of Microglia is thought to result in neuronal injury, the M-CSF system may be a potential target for therapeutic intervention in AD

255. O'Barr S, Cooper NR (2000) The C5a complement activation peptide increases IL-1beta and IL-6 release from amyloid-beta primed human monocytes: implications for Alzheimer's disease. J.Neuroimmunol. 109:87-94
     Abstract: Alzheimer's disease (AD) brains contain large numbers of amyloid-beta peptide (Abeta) deposits associated with activated Microglia, astrocytes and dystrophic neurites. Activated complement components and pro-inflammatory cytokines are also present, indicative of focal inflammation. However, neither Abeta, nor the chemokine-like mediator, C5a, which is generated by Abeta-mediated complement activation, significantly activates Microglia, as assessed by pro-inflammatory cytokine release. We evaluated the possibility that both together would co-stimulate such release using the THP-1 human monocytic cell line as a Microglial surrogate, and found this to be the case. These studies support the hypothesis that Abeta and C5a induce a chronic Microglia-mediated focal inflammatory response in AD

256. Ogawa K, Yamada T, Tsujioka Y, Taguchi J, Takahashi M, Tsuboi Y, Fujino Y, Nakajima M, Yamamoto T, Akatsu H, Mitsui S, Yamaguchi N (2000) Localization of a novel type trypsin-like serine protease, neurosin, in brain tissues of Alzheimer's disease and Parkinson's disease. Psychiatry Clin.Neurosci. 54:419-426
     Abstract: Neurosin, a novel type of trypsin-like serine protease, has been shown to be preferentially expressed in human brain by northern blotting. We examined neurosin immunolabeling in the brains of neurologically normal persons and patients with Alzheimer's disease (AD) and with Parkinson's disease. We also identified the expression of the mRNA for neurosin by in situ hybridization histochemistry and reverse transcription-polymerase chain reaction (RT-PCR). The neurosin antibody stained all of the nuclei of various cell types. In neurons, there was also staining of neuronal cytoplasm, nucleoli and their processes. In AD, staining of neurons with processes was rare in the damaged areas. Some senile plaques, extracellular tangles and Lewy bodies were also positive for neurosin. Expression of the mRNA for neurosin was seen in neurons in the gray matter, and in Microglial cells in the white matter. In AD, the intensity of the signal for neurosin mRNA in the gray matter was decreased compared with normal control brains. The relative levels of neurosin mRNA in AD brains, measured by RT-PCR, were lower than those in controls. These results suggest that in human brain neurosin plays various physiological roles, and that in AD this molecule, like other serine proteases, may have a role in the degradation of such substances as beta-amyloid protein

257. Ogawa O, Umegaki H, Sumi D, Hayashi T, Nakamura A, Thakur NK, Yoshimura J, Endo H, Iguchi A (2000) Inhibition of inducible nitric oxide synthase gene expression by indomethacin or ibuprofen in beta-amyloid protein-stimulated J774 cells. Eur.J.Pharmacol. 408:137-141
     Abstract: Recent studies show that a mononuclear phagocyte lineage, including Microglia, plays a possible role in the pathogenesis of Alzheimer's disease through nitric oxide (NO)-mediated neurotoxicity. Epidemiological studies show that nonsteroidal anti-inflammatory drugs (NSAIDs) have a protective effect against Alzheimer's disease. Based on these observations, it has been hypothesized that an anti-Alzheimer's disease effect of NSAIDs could result from the inhibition of NO synthesis. We report here that indomethacin or ibuprofen dose-dependently reduce beta-amyloid protein and interferon-gamma-induced NO production, accompanied by an inhibition of inducible nitric oxide synthase mRNA expression in J774 cells, a murine macrophage cell line. Aspirin, however, does not produce such an effect, suggesting that the cyclooxygenases pathway is not involved in the inhibitory effects of NSAIDs on beta-amyloid protein and interferon-gamma-induced NO production in J774 cells

258. Overmyer M, Kraszpulski M, Helisalmi S, Soininen H, Alafuzoff I (2000) DNA fragmentation, gliosis and histological hallmarks of Alzheimer's disease. Acta Neuropathol.(Berl) 100:681-687
     Abstract: The extent of DNA fragmentation analysed using the TUNEL technique was evaluated in post-mortem human brain tissue. Twenty-four patients with clinical and histopathological diagnosis of Alzheimer's disease (AD) and a short post-mortem delay were analysed. We report an increase in the count of TUNEL-labelled cells as the pathology of AD intensifies. Our results point out a significant correlation between neurofibrillary tangle and senile/neuritic plaque score and TUNEL-labelled cells. Patients with two copies of apolipoprotein (Apo) Eepsilon4 allele had highest number of histopathological hallmarks lesions of AD, whereas the ApoE genotype did not significantly influence the density of TUNEL-positive cells. No significant correlation was found between beta-amyloid protein load and TUNEL-labelled cells. There was no relationship between the age at death, age at onset, extent of astrogliosis or microgliosis and TUNEL-labelled cells in our material

259. Reynolds WF, Hiltunen M, Pirskanen M, Mannermaa A, Helisalmi S, Lehtovirta M, Alafuzoff I, Soininen H (2000) MPO and APOEepsilon4 polymorphisms interact to increase risk for AD in Finnish males. Neurology 55:1284-1290
     Abstract: BACKGROUND: Myeloperoxidase (MPO) is present in senile plaques and surrounding reactive Microglia, but not in normal brain parenchyma. MPO in plaques is highest in APOE epsilon4 carriers, suggesting a functional interaction. An MPO promoter polymorphism (-463G/A) linked to increased MPO expression has been associated with increased risk of AD. METHODS: To further define the possible interaction of MPO and APOE epsilon4, we examined 127 patients with AD and 174 controls from a genetically homogeneous Finnish population. RESULTS: A significantly higher percentage of male patients with AD carried the MPO A and APOE epsilon4 alleles relative to men carrying neither allele (p < 0.001; OR, 11.4; 95% CI, 3.6 to 6.7). Male APOE epsilon4 carriers lacking the MPO A allele had an OR of 3.0 (p = 0.01; 95% CI, 1.3 to 6.9), indicating that MPO A enhances AD risk by 3.8-fold. Age at onset was lower in men carrying the MPO A and APOE epsilon4 alleles (Kaplan-Meier survival analysis; p = 0.01). Also, the MPO AA genotype was associated with selective mortality in men, but not in women. AA genotypes were absent from 159 male patients with AD and controls, representing the expected 5% to 6% in women and male controls younger than age 20. The -463A creates an estrogen receptor binding site that may contribute to these gender differences. CONCLUSIONS: MPO A and APOE epsilon4 alleles interact to increase the risk of AD in men but not in women in this Finnish cohort

260. Rozemuller AJ, Eikelenboom P, Theeuwes JW, Jansen Steur EN, de Vos RA (2000) Activated Microglial cells and complement factors are unrelated to cortical Lewy bodies. Acta Neuropathol.(Berl) 100:701-708
     Abstract: Inflammatory mechanisms have been demonstrated in Alzheimer's disease (AD) but their presence in other neurodegenerative disorders is not well documented. Complement factors and activated Microglia have been reported in the substantia nigra of Parkinson's disease (PD). In the present study we investigated the cingulate gyrus of 25 autopsied patients with clinically and neuropathologically well-documented PD, with or without dementia, for the presence of (activated) Microglial cells and their relation with Lewy body (LB)-bearing neurons. In addition, we studied the presence of complement factors in LBs. Of the 25 patient, 15 were clinically demented, fulfilling criteria for dementia with LBs (DLB); 7 also fulfilled CERAD morphological criteria for probable or definite Alzheimer type of dementia. Microglia clustering was seen around congophilic plaques with or without tau pathology. Microglial cells were not associated with LB-bearing neurons or noncongophilic plaques. The cortex of DLB patients without AD plaques did not show more Microglial cells than the cortex of non-demented controls. The number of Microglia was the lowest in young control patients who died immediately after trauma. Complement factor C3d was occasionally seen in diffusely ubiquinated neurons but late complement factors were not detected in these neurons. Double staining for complement and alpha-synuclein was negative, suggesting the absence of complement in LBs. In contrast, AD plaques in the same sections showed complement factors C3c, C3d, C1q and C5-9. In conclusion, we have found no evidence that inflammatory mechanism are involved in LB formation in cerebral cortex

261. Samatovicz RA (2000) Genetics and brain injury: apolipoprotein E. J.Head Trauma Rehabil. 15:869-874
     Abstract: Apolipoprotein E (apo E) is a lipoprotein produced by astrocytes and Microglia and has a proposed role in transporting lipids to injured neurons. There are three known isoforms of apo E, coded for by the APOE epsilon2, APOE epsilon3, and APOE epsilon4 genes. The APOE epsilon4 genotype has been implicated as a risk factor for Alzheimer's disease. Recent studies have suggested that APOE epsilon4 may influence the central nervous system's response to injury. This article presents an overview of the relationship between apo E, Alzheimer's disease, and head injury and reviews recent studies implicating APOE epsilon4 as a possible genetic determinant in recovery from head injury

262. Satoh J, Kuroda Y (2000) Amyloid precursor protein beta-secretase (BACE) mRNA expression in human neural cell lines following induction of neuronal differentiation and exposure to cytokines and growth factors. Neuropathology. 20:289-296
     Abstract: Recently, a novel amyloid precursor protein beta-secretase (designated BACE) was identified. Because activated Microglia and astrocytes play a role in amyloidogenesis in Alzheimer's disease, the constitutive and glial cytokine/growth factor-regulated expression of BACE was studied in human neural cell lines. By reverse transcription-polymerase chain reaction (RT-PCR) analysis, BACE mRNA expression was identified in various human neural and non-neural cell lines. By northern blot analysis, the expression of BACE mRNA composed of five distinct transcripts (>8.0, 7.0, 6.0, 4.4 and 2.6 kb) was elevated markedly in NTera2 teratocarcinoma cells following retinoic acid-induced neuronal differentiation. But the levels of three major BACE mRNA species (7.0, 6.0 and 4.4 kb) were not significantly altered in NTera2-derived neurons, SK-N-SH neuroblastoma or U-373MG astrocytoma following exposure to tumor necrosis factor-alpha, interleukin (IL)-1beta, IL-6, interferon-gamma, transforming growth factor-beta1, epidermal growth factor, basic fibroblast growth factor, brain-derived neurotrophic factor, dibutyryl cyclic adenosine monophosphate or phorbol 12-myristate 13-acetate. These results indicate that BACE mRNA is expressed constitutively in human neural cells and its expression is upregulated during neuronal differentiation, but it is unlikely to be regulated by activated glia-derived cytokines and growth factors

263. Scali C, Prosperi C, Vannucchi MG, Pepeu G, Casamenti F (2000) Brain inflammatory reaction in an animal model of neuronal degeneration and its modulation by an anti-inflammatory drug: implication in Alzheimer's disease. Eur.J.Neurosci. 12:1900-1912
     Abstract: Brain inflammatory processes underlie the pathogenesis of Alzheimer's disease, and nonsteroidal anti-inflammatory drugs have a protective effect in the disease. The aim of this study was to characterize in vivo in the rat brain the inflammatory reaction in response to excitotoxic insult and to investigate the efficacy of nimesulide treatment. Quisqualic acid was injected into the right nucleus basalis of rats. The excitotoxin induced cholinergic degeneration, an intense glial reaction and the production of inflammatory mediators. Three hours after injection, a five-fold elevation in the concentration of interleukin-1beta in the injected area was observed. This elevation was reduced by 50% by nimesulide (10 mg/kg, i.m.) pretreatment. Electron microscope examination and immunocytochemical staining revealed an intense activation of Microglia and astrocytes at both 24 h and 7 days after injection. Cyclooxygenase-2-immunoreactivity was induced in the blood vessels of the injected hemisphere in perivascular Microglial and endothelial cells 24 h after injection. Seven days postinjection, a cyclooxygenase-2-positive signal was induced in the parenchymal Microglia and large amounts of prostaglandin-E2 were measured in the injected area. Twenty-four hours and 7 days after injection, many inducible nitric oxide synthase-positive cells and a high level of nitrite were detected at the injection site. Seven days of nimesulide (10 mg/kg/day, i.m.) treatment strongly attenuated the Microglial reaction, reduced the number of inducible nitric oxide synthase-positive cells and completely abolished the increase in prostaglandin-E2 formation. These data provide valuable support in vivo for the potential efficacy of cyclooxygenase-2 inhibitors in Alzheimer's disease therapy

264. Schubert P, Morino T, Miyazaki H, Ogata T, Nakamura Y, Marchini C, Ferroni S (2000) Cascading glia reactions: a common pathomechanism and its differentiated control by cyclic nucleotide signaling. Ann.N.Y.Acad.Sci. 903:24-33
     Abstract: A pathological glia activation, stimulated by inflammatory proteins, beta-amyloid, or brain ischemia, is discussed as a common pathogenic factor for progressive nerve cell damage in vascular and Alzheimer dementia. A critical point seems to be reached, if the cytokine-controlled Microglial upregulation causes a secondary activation of astrocytes which loose the negative feedback control, are forced to give up their physiological buffering function, and may add to neuronal damage by the release of nitric oxide (NO) and by promoting toxic beta-amyloid formation. A strengthening of the cyclic adenosine-5',3'-monophosphate (cAMP) signaling exerted a differential inhibition of the stimulatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) released from cultured rat Microglia, but maintained the negative feedback signal IL-6; cAMP inhibited also the release of free oxygen radicals (OR) but not of NO. Reinforcement of the NO-induced cyclic guanosine monophosphate (cGMP) increase by blockade of the phosphodiesterase (PDE) subtype-5 with propentofylline counterbalanced the toxic NO action that causes with OR neuronal damage by peroxynitrate formation. In rat cultured astrocytes, a prolonged cAMP elevation favored cell differentiation, the expression of a mature ion channel patter, and an improvement of the extracellular glutamate uptake. Cyclic AMP signaling could be strengthened by PDE blockade and by raising extracellular adenosine, which stimulates A2 receptor-mediated cAMP synthesis. Via an A1 receptor-mediated effect, elevated adenosine was found to overcome a deficient intracellular calcium mobilization resulting from an impaired muscarinic signaling at pathologically decreased acetylcholine concentrations. We suggest that pharmaca, which elevate extracellular adenosine and/or block the degradation of cyclic nucleotides, may be used to counteract glia-related neuronal damage in dementing processes

265. Sheffield LG, Marquis JG, Berman NE (2000) Regional distribution of cortical Microglia parallels that of neurofibrillary tangles in Alzheimer's disease. Neurosci.Lett. 285:165-168
     Abstract: It has been postulated that Microglia contribute to the development of neurofibrillary tangles (NFT) in Alzheimer's disease (AD). We compared the distribution of Microglia with that of NFT in both AD and non-AD cases. In AD cases, we found that the extent of area covered by Ricinus communic agglutinin-1 labeled Microglia generally paralleled NFT frequency and distribution. Microglia occupied the greatest area in tangle-rich periallocortex/allocortex, a lesser area in association cortex, and the smallest area in tangle-poor primary cortex. Interestingly, this pattern was also present in non-AD cases where there were few to no NFT. These findings suggest that regional variations in Microglial distribution may constitute, at least in part, a template for the development of NFT

266. Shepherd CE, Thiel E, McCann H, Harding AJ, Halliday GM (2000) Cortical inflammation in Alzheimer disease but not dementia with Lewy bodies. Arch.Neurol. 57:817-822
     Abstract: BACKGROUND: There have been no previous studies on the role of inflammation in the brain for the second most common dementing disorder, dementia with Lewy bodies. OBJECTIVE: To investigate the degree of cortical inflammation in dementia with Lewy bodies (DLB) compared with Alzheimer disease (AD) and control brains. DESIGN AND MAIN OUTCOME MEASURES: Post-mortem tissue collection from a brain donor program using standardized diagnostic criteria. Brains collected from January 1, 1993, through December 31, 1996, were screened and selected only for the presence or absence of tau neuritic plaques. Results of immunohistochemistry for HLA-DR were quantified using area fraction counts. Counts were performed by investigators who were unaware of the diagnosis. Results were compared across groups using analysis of variance and posthoc testing. SETTING: A medical research institute in Sydney, Australia. PATIENTS: Eight brains with DLB and without the tau neuritic plaques typical of AD, 10 brains with AD and no Lewy bodies, and 11 nondemented controls without significant neuropathological features were selected from a consecutive sample. RESULTS: Compared with AD, DLB demonstrated significantly less inflammation in the form of HLA-DR-reactive Microglia in all cortical regions (P<.001, posthoc). The level of inflammation in DLB was comparable to that seen in controls (P=.54, post hoc). CONCLUSIONS: Inflammation appears related to the tau neuritic plaques of AD. Despite similar clinical presentations, therapeutic anti-inflammatory strategies are not likely to be effective for pure DLB. Arch Neurol. 2000

267. Shimohama S, Tanino H, Kawakami N, Okamura N, Kodama H, Yamaguchi T, Hayakawa T, Nunomura A, Chiba S, Perry G, Smith MA, Fujimoto S (2000) Activation of NADPH oxidase in Alzheimer's disease brains. Biochem.Biophys.Res.Commun. 273:5-9
     Abstract: The present study is the first to show that superoxide (O(-)(2)) forming NADPH oxidase is activated in Alzheimer's disease (AD) brains by demonstrating the marked translocation of the cytosolic factors p47-phox and p67-phox to the membrane. In conjunction with a recent in vitro study showing that amyloid beta activates O(-)(2) forming NADPH oxidase in Microglia, where these phox proteins are localized in this study, the present results suggest that, in AD, NADPH oxidase is activated in Microglia, resulting in the formation of reactive oxygen species which can be toxic to neighboring neurons in AD

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

269. Sigurdsson EM, Permanne B, Soto C, Wisniewski T, Frangione B (2000) In vivo reversal of amyloid-beta lesions in rat brain. J.Neuropathol.Exp.Neurol. 59:11-17
     Abstract: Cerebral amyloid-beta (Abeta) deposition is central to the neuropathological definition of Alzheimer disease (AD) with Abeta related toxicity being linked to its beta-sheet conformation and/or aggregation. We show that a beta-sheet breaker peptide (iAbeta5) dose-dependently and reproducibly induced in vivo disassembly of fibrillar amyloid deposits, with control peptides having no effect. The iAbeta5-induced disassembly prevented and/or reversed neuronal shrinkage caused by Abeta and reduced the extent of interleukin-1beta positive Microglia-like cells that surround the Abeta deposits. These findings suggest that beta-sheet breakers, such as iAbeta5 or similar peptidomimetic compounds, may be useful for reducing the size and/or number of cerebral amyloid plaques in AD, and subsequently diminishing Abeta-related histopathology

270. Simic G, Lucassen PJ, Krsnik Z, Kruslin B, Kostovic I, Winblad B, Bogdanovi (2000) nNOS expression in reactive astrocytes correlates with increased cell death related DNA damage in the hippocampus and entorhinal cortex in Alzheimer's disease. Exp.Neurol. 165:12-26
     Abstract: The immunocytochemical distribution of the neuronal form of nitric oxide synthase (nNOS) was compared with neuropathological changes and with cell death related DNA damage (as revealed by in situ end labeling, ISEL) in the hippocampal formation and entorhinal cortex of 12 age-matched control subjects and 12 Alzheimer's disease (AD) patients. Unlike controls, numerous nNOS-positive reactive astrocytes were found in AD patients around beta-amyloid plaques in CA1 and subiculum and at the places of clear and overt neuron loss, particularly in the entorhinal cortex layer II and CA4. This is the first evidence of nNOS-like immunoreactivity in reactive astrocytes in AD. In contrast to controls, in all but one AD subject, large numbers of ISEL-positive neuronal nuclei and Microglial cells were found in the CA1 and CA4 regions and subiculum. Semiquantitative analysis showed that neuronal DNA fragmentation in AD match with the distribution of nNOS-expressing reactive astroglial cells in CA1 (r = 0.74, P < 0.01) and CA4 (r = 0.58, P < 0.05). A portion of the nNOS-positive CA2/CA3 pyramidal neurons was found to be spared even in the most affected hippocampi. A significant inverse correlation between nNOS expression and immunoreactivity to abnormally phosphorylated tau proteins (as revealed by AT8 monoclonal antibody) in perikarya of these CA2/3 neurons (r = -0.85, P < 0.01) suggests that nNOS expression may provide selective resistance to neuronal degeneration in AD. In conclusion, our results imply that an upregulated production of NO by reactive astrocytes may play a key role in the pathogenesis of AD

271. Stoltzner SE, Grenfell TJ, Mori C, Wisniewski KE, Wisniewski TM, Selkoe DJ, Lemere CA (2000) Temporal accrual of complement proteins in amyloid plaques in Down's syndrome with Alzheimer's disease. Am.J.Pathol. 156:489-499
     Abstract: The complement system constitutes a series of enzymatic steps involved in the inflammatory response and is activated in Alzheimer's disease (AD). Using Down's syndrome (DS) brains as a temporal model for the progression of AD, we examined components of the complement cascade and their relationship to other principal events in AD pathology: Abeta42 deposition, neuritic changes, neurofibrillary tangles (NFTs), and gliosis (reactive astrocytes, activated Microglia). Adjacent sections of frontal cortex from 24 DS subjects ranging in age from 12 to 73 years were immunohistochemically examined for immunoreactivity (IR) of classical complement proteins (Clq and C3), markers indicating activation of complement (C4d and C5b-9), the complement inhibitor apolipoprotein J (apo J), and markers of AD neuropathology. Abeta42-labeled diffuse plaques were first detected in a 12-year-old DS subject and were not labeled by any of the complement antibodies. Colocalization of Abeta42 with Clq, C3, C4d, and/or apo J was first detected in compacted plaques in the brain of a 15-year-old DS patient with features of mature AD pathology, such as reactive astrocytes, activated Microglia, dystrophic neurites, and a few NFTs. IR for C4d and C5b-9 (membrane attack complex, MAC) was observed in small numbers of plaque-associated dystrophic neurites and in focal regions of pyramidal neurons in this 15-year-old. The only other young (</=30 years) DS brain to show extensive complement IR was that of a 29-year-old DS subject who also displayed the full range of AD neuropathological features. All middle-aged and old DS brains showed IR for Clq and C3, primarily in compacted plaques. In these cases, C4d IR was found in a subset of Abeta42 plaques and, along with C5b-9 IR, was localized to dystrophic neurites in a subset of neuritic plaques, neurons, and some NFTs. Our data suggest that in AD and DS, the classical complement cascade is activated after compaction of Abeta42 deposits and, in some instances, can progress to the local neuronal expression of the MAC as a response to Abeta plaque maturation

272. Taguchi J, Fujii A, Fujino Y, Tsujioka Y, Takahashi M, Tsuboi Y, Wada I, Yamada T (2000) Different expression of calreticulin and immunoglobulin binding protein in Alzheimer's disease brain. Acta Neuropathol.(Berl) 100:153-160
     Abstract: Both calreticulin (CRT) and immunoglobulin binding protein (Bip) have a role in the folding and assembly of oligomeric membrane proteins in the endoplasmic reticulum (ER). Recent studies have demonstrated the generation of beta-amyloid protein (Abeta) 1-42, a key peptide for amyloid deposits, in the ER. We, therefore, examined the localization and expression of CRT, Bip and their mRNA by immunohistochemistry, Western blot, in situ hybridization and semiquantitative reverse transcription polymerase chain reaction (RT-PCR) in both neurologically normal and Alzheimer's disease (AD) brains. Two polyclonal anti-CRT antibodies gave similar positive staining of CRT in neurons and glia. In neuronal cells, the cytoplasm, nucleoli and their processes were positive for CRT. In glial cells, perinuclear staining was frequently seen and the processes of some glial cells were also stained. In AD, these antibodies stained clearly damaged neurons but the number and the intensity of positive cells were decreased compared to controls. Processes of Microglial cells were markedly positive in the AD white matter. Western blots using an anti-CRT antibody showed significantly lower immunoreactive bands in AD than control brains. By in situ hybridization, the number of neurons which express the CRT mRNA was less in AD than in controls. Using RT-PCR, the relative levels of the CRT mRNA in AD brains were also found to be significantly lower than those in controls. On the other hand, the number of Bip-positive cell, the production of Bip and the expression of mRNA for Bip did not differ between control and AD brains. These results suggest that CRT may be a multifunctional protein in human brain, and that the weak expression of CRT and the positive staining of Microglial processes in AD brain may be part of the pathological processes in AD

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

274. Tan J, Town T, Mori T, Wu Y, Saxe M, Crawford F, Mullan M (2000) CD45 opposes beta-amyloid peptide-induced Microglial activation via inhibition of p44/42 mitogen-activated protein kinase. J.Neurosci. 20:7587-7594
     Abstract: Reactive Microglia have been suggested to play a role in the Alzheimer's disease (AD) process, and previous studies have shown that expression of CD45, a membrane-bound protein-tyrosine phosphatase (PTP), is elevated in Microglia in AD brain compared with controls. To investigate the possible role of CD45 in Microglial responsiveness to beta-amyloid (Abeta) peptides, we first co-treated primary cultured Microglia with a tyrosine phosphatase inhibitor [potassium bisperoxo (1,10-phenanthroline) oxovanadate (phen), 5 micrometer] and freshly solubilized Abeta peptides (1000 nm). Data show synergistic induction of Microglial activation as evidenced by tumor necrosis factor alpha (TNF-alpha) production and nitric oxide (NO) release, both of which we show to be dependent on activation of p44/42 mitogen-activated protein kinase (MAPK). Furthermore, co-treatment with phen and Abeta peptides results in Microglia-induced neuronal cell injury. Stimulation of Microglial CD45 by anti-CD45 antibody markedly inhibits these effects via inhibition of p44/42 MAPK, suggesting that CD45 is a negative regulator of Microglial activation. Accordingly, primary cultured Microglia from CD45-deficient mice demonstrate hyper-responsiveness to Abeta, as evidenced by TNF-alpha release, NO production, and neuronal injury after stimulation with Abeta peptides. As a validation of these findings in vivo, brains from a transgenic mouse model of AD [transgenic Swedish APP-overexpressing (Tg APP(sw)) mice] deficient for CD45 demonstrate markedly increased production of TNF-alpha compared with Tg APP(sw) mice. Taken together, these results suggest that therapeutic agents that stimulate the CD45 PTP signaling pathway may be effective in suppressing Microglial activation associated with AD

275. Terry RD (2000) Cell death or synaptic loss in Alzheimer disease. J.Neuropathol.Exp.Neurol. 59:1118-1119
     Abstract: It is an erroneous but common assumption that loss of neuronal perikarya causes the cognitive change in Alzheimer disease. Neither are senile plaques nor neurofibrillary tangles primarily to blame. In fact, it is the loss of synaptic contact that leads directly to the personal devastation. The death of neocortical synapses in the neuropil between plaques is probably the factor that activates the Microglia

276. Togo T, Akiyama H, Kondo H, Ikeda K, Kato M, Iseki E, Kosaka K (2000) Expression of CD40 in the brain of Alzheimer's disease and other neurological diseases. Brain Res. 885:117-121
     Abstract: We have investigated immunohistochemically the expression of CD40 in post-mortem human brain tissues. In control brain, the blood vessels were stained weakly for CD40. Vascular expression of CD40 was enhanced in the lesions of Alzheimer's disease and some other neurological diseases. In such diseases, reactive Microglia were also positive for CD40. The results of this study suggest that CD40 expression by Microglia is up-regulated upon a variety of brain insults and is not limited to lesions with amyloid beta-protein deposits

277. Trieu VN, Uckun FM (2000) Apolipoprotein E and apolipoprotein D expression in a murine model of singlet oxygen-induced cerebral stroke. Biochem.Biophys.Res.Commun. 268:835-841
     Abstract: Apolipoprotein E (apoE)-deficient mice exhibit neuronal abnormalities similar to those in Alzheimer's disease and enhanced sensitivity to stroke-associated injuries. Here, we show that apoE deficiency results in impaired Microglia/macrophage recruitment and accumulation after cerebral infarct. Astrogliosis and apolipoprotein D (apoD) expression are unaffected, suggesting that the neurological abnormalities of apoE-deficient mice could be due to impaired Microglia/macrophage recruitment/accumulation, which is important for the clearance of neurodegenerative products via reverse cholesterol transport. To our knowledge, the results presented herein provide the first experimental evidence that brain Microglia/macrophage recruitment/accumulation is affected by apoE deficiency. The insights gained from this study should facilitate the elucidation of the role of apoE in neurological disorders such as dementia with stroke and Alzheimer's disease

278. Vekrellis K, Ye Z, Qiu WQ, Walsh D, Hartley D, Chesneau V, Rosner MR, Selkoe DJ (2000) Neurons regulate extracellular levels of amyloid beta-protein via proteolysis by insulin-degrading enzyme. J.Neurosci. 20:1657-1665
     Abstract: Progressive cerebral accumulation of amyloid beta-protein (Abeta) is an early and invariant feature of Alzheimer's disease. Little is known about how Abeta, after being secreted, is degraded and cleared from the extracellular space of the brain. Defective Abeta degradation could be a risk factor for the development of Alzheimer's disease in some subjects. We reported previously that Microglial cells release substantial amounts of an Abeta-degrading protease that, after purification, is indistinguishable from insulin-degrading enzyme (IDE). Here we searched for and characterized a role for IDE in Abeta degradation by neurons, the principal cell type that produces Abeta. Whole cultures of differentiated pheochromocytoma (PC12) cells and primary rat cortical neurons actively degraded endogenously secreted Abeta via IDE. However, unlike that in Microglia, IDE in differentiated neurons was not released but localized to the cell surface, as demonstrated by biotinylation. Undifferentiated PC12 cells released IDE into their medium, whereas after differentiation, IDE was cell associated but still degraded Abeta in the medium. Overexpression of IDE in mammalian cells markedly reduced the steady-state levels of extracellular Abeta(40) and Abeta(42), and the catalytic site mutation (E111Q) abolished this effect. We observed a novel membrane-associated form of IDE that is approximately 5 kDa larger than the known cytosolic form in a variety of cells, including differentiated PC12 cells. Our results support a principal role for membrane-associated and secreted IDE isoforms in the degradation and clearance of naturally secreted Abeta by neurons and Microglia

279. Webster SD, Yang AJ, Margol L, Garzon-Rodriguez W, Glabe CG, Tenner AJ (2000) Complement component C1q modulates the phagocytosis of Abeta by Microglia. Exp.Neurol. 161:127-138
     Abstract: Recent studies showing that Microglia internalize the amyloid beta-peptide (Abeta) suggest that these cells have the potential for clearing Abeta deposits in Alzheimer's disease, and mechanisms that regulate the removal of Abeta may therefore be of clinical interest. Previous studies from this laboratory showing that C1q enhances phagocytosis of cellular targets by rat Microglia prompted the current investigations characterizing the effects of C1q on Microglial phagocytosis of Abeta. Microglia were shown to phagocytose Abeta1-42, in agreement with observations of other investigators. Uptake of Abeta1-42 was observed for concentrations of 5-50 microM, and phagocytosis of peptides containing (14)C or fluorescein (FM) labels was not affected by the interaction of Microglia with C1q-coated surfaces. However, inclusion of C1q (125 nM-1.4 microM) in solutions of 50 microM Abeta1-42 inhibited the uptake of (14)C-Abeta1-42 and FM-Abeta1-42, suggesting that C1q blocks the interaction of Abeta with Microglia. Uptake of Abeta was partially blocked by the scavenger receptor ligands polyinosinic acid and maleylated BSA. Inhibition of Abeta uptake by C1q may contribute to the accumulation of fibrillar, C1q-containing plaques that occurs in parallel with disease progression. These data suggest that mechanisms which interfere with the binding of C1q to Abeta may be of therapeutic value both through inhibition of the inflammatory events resulting from complement activation and via altered access of Abeta sites necessary for ingestion by Microglia

280. Wegiel J, Wang KC, Tarnawski M, Lach B (2000) Microglia cells are the driving force in fibrillar plaque formation, whereas astrocytes are a leading factor in plague degradation. Acta Neuropathol.(Berl) 100:356-364
     Abstract: Ultrastructural three-dimensional reconstruction of human classical plaques in different stages of development shows that Microglial cells are the major factor driving plaque formation by fibrillar amyloid-beta (Abeta) deposition. The amount of fibrillar Abeta released by Microglial cells and the area of direct contact between amyloid and neuron determine the extent of dystrophic changes in neuronal processes and synapses. The volume of hypertrophic astrocytic processes separating fibrillar amyloid from neuron is a measure of the protective activation of astrocytes. On the bases of the volume of amyloid star, Microglial cells, dystrophic neurites, and hypertrophic astrocytic processes, and spatial relationships between plaque components, three stages in classical plaque development have been distinguished: early, mature, and late. In early plaque, the leading pathology is fibrillar Abeta deposition by Microglial cells with amyloid star formation. The mature plaque is characterized by a balance between amyloid production, neuronal dystrophy, and astrocyte hypertrophy. In late classical plaque, Microglial cells retract and expose neuropil on direct contact with amyloid star, enhancing both dystrophic changes in neurons and hypertrophic changes in astrocytes. In late plaques, activation of astrocytes predominates. They degrade amyloid star and peripheral amyloid wisps. The effect of these changes is classical plaque degradation to fibrillar primitive and finally to nonfibrillar, diffuse-like plaques

281. Weiner HL, Lemere CA, Maron R, Spooner ET, Grenfell TJ, Mori C, Issazadeh S, Hancock WW, Selkoe DJ (2000) Nasal administration of amyloid-beta peptide decreases cerebral amyloid burden in a mouse model of Alzheimer's disease. Ann.Neurol. 48:567-579
     Abstract: Progressive cerebral deposition of amyloid-beta (Abeta) peptide, an early and essential feature of Alzheimer's disease (AD), is accompanied by an inflammatory reaction marked by microgliosis, astrocytosis, and the release of proinflammatory cytokines. Mucosal administration of disease-implicated proteins can induce antigen-specific anti-inflammatory immune responses in mucosal lymphoid tissue which then act systemically. We hypothesized that chronic mucosal administration of Abeta peptide might induce an anti-inflammatory process in AD brain tissue that could beneficially affect the neuropathological findings. To test this hypothesis, we treated PDAPP mice, a transgenic line displaying numerous neuropathological features of AD, between the ages of approximately 5 and approximately 12 months with human Abeta synthetic peptide mucosally each week. We found significant decreases in the cerebral Abeta plaque burden and Abeta42 levels in mice treated intranasally with Abeta peptide versus controls treated with myelin basic protein or left untreated. This lower Abeta burden was associated with decreased local Microglial and astrocytic activation, decreased neuritic dystrophy, serum anti-Abeta antibodies of the IgG1 and IgG2b classes, and mononuclear cells in the brain expressing the anti-inflammatory cytokines interleukin-4, interleukin-10, and tumor growth factor-beta. Our results demonstrate that chronic nasal administration of Abeta peptide can induce an immune response to Abeta that decreases cerebral Abeta deposition, suggesting a novel mucosal immunological approach for the treatment and prevention of AD

282. Wisniewski HM, Wegiel J, Vorbrodt AW, Mazur-Kolecka B, Frackowiak J (2000) Role of perivascular cells and myocytes in vascular amyloidosis. Ann.N.Y.Acad.Sci. 903:6-18
     Abstract: Amyloidogenic processing of amyloid-beta precursor protein (APP) by cells of the brain is the major pathologic component of Alzheimer's disease. Amyloid-beta (A beta) is of heterogeneous origin. Perivascular cells of monocyte-macrophage-Microglial cell lineage produce fibrillar A beta in the wall of capillaries, whereas parenchymal Microglial cells produce fibri