51
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Gasque P, Dean YD, McGreal EP, VanBeek J, Morgan BP. Complement components of the innate immune system in health and disease in the CNS. IMMUNOPHARMACOLOGY 2000; 49:171-86. [PMID: 10904116 DOI: 10.1016/s0162-3109(00)80302-1] [Citation(s) in RCA: 253] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The innate immune system and notably the complement (C) system play important roles in host defense to recognise and kill deleterious invaders or toxic entities, but activation at inappropriate sites or to an excessive degree can cause severe tissue damage. C has been implicated as a factor in the exacerbation and propagation of tissue injury in numerous diseases including neurodegenerative disorders. In this article, we review the evidence indicating that brain cells can synthesise a full lytic C system and also express specific C inhibitors (to protect from C activation and C lysis) and C receptors (involved in cell activation, chemotaxis and phagocytosis). We also summarise the mechanisms involved in the antibody-independent activation of the classical pathway of C in Alzheimer's disease, Huntington's disease and Pick's disease. Although the primary role of C activation on a target cell is to induce cell lysis (particularly of neurons), we present evidence indicating that C (C3a, C5a, sublytic level of C5b-9) may also be involved in pro- as well as anti-inflammatory activities. Moreover, we discuss evidence suggesting that local C activation may contribute to tissue remodelling activities during repair in the CNS.
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Affiliation(s)
- P Gasque
- Department of Medical Biochemistry, University of Wales College of Medicine, Cardiff, UK.
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52
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Emmerling MR, Watson MD, Raby CA, Spiegel K. The role of complement in Alzheimer's disease pathology. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1502:158-71. [PMID: 10899441 DOI: 10.1016/s0925-4439(00)00042-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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.
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Affiliation(s)
- M R Emmerling
- Neuroscience Therapeutics, Parke-Davis Pharmaceutical Research Division, Warner-Lambert Company, Ann Arbor, MI 48106, USA.
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53
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Hüll M, Lieb K, Fiebich BL. Anti-inflammatory drugs: a hope for Alzheimer's disease? Expert Opin Investig Drugs 2000; 9:671-83. [PMID: 11060701 DOI: 10.1517/13543784.9.4.671] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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.
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Affiliation(s)
- M Hüll
- Department of Psychiatry, University of Freiburg Medical School, Hauptstr. 5, D - 79104 Freiburg, Germany.
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54
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Abstract
Studies of the molecular basis of Alzheimer's disease exemplify the increasingly blurred distinction between basic and applied biomedical research. The four genes so far implicated in familial Alzheimer's disease have each been shown to elevate brain levels of the self-aggregating amyloid-beta protein, leading gradually to profound neuronal and glial alteration, synaptic loss and dementia. Progress in understanding this cascade has helped to identify specific therapeutic targets and provides a model for elucidating other neurodegenerative disorders.
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Affiliation(s)
- D J Selkoe
- Center for Neurologic Diseases, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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55
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Abstract
Among several pathogenetic elements underlying Alzheimer's disease (AD), a brain-specific inflammatory response has recently attracted attention as a cause of neurodegeneration and progressive cognitive decline. Markers of inflammation in AD are activated microglial cells, synthesis of cytokines, acute-phase proteins and complement proteins in areas of brain destruction. Epidemiological studies point to a reduced risk of AD among users of anti-inflammatory drugs. Influencing inflammatory parameters has become the focus of several new treatment strategies and a clinical trial with indomethacin shows promising results. The results from current clinical trials with steroidal and non-steroidal anti-inflammatory drugs will be available in the near future.
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56
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Bergamaschini L, Canziani S, Bottasso B, Cugno M, Braidotti P, Agostoni A. Alzheimer's beta-amyloid peptides can activate the early components of complement classical pathway in a C1q-independent manner. Clin Exp Immunol 1999; 115:526-33. [PMID: 10193429 PMCID: PMC1905247 DOI: 10.1046/j.1365-2249.1999.00835.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
beta-Amyloid (beta-A) accumulates in the brain of patients with Alzheimer's disease (AD) and is presumably involved in the pathogenesis of this disease, on account of its neurotoxicity and complement-activating ability. Although assembly of beta-A in particular aggregates seems to be crucial, soluble non-fibrillar beta-A may also be involved. Non-fibrillar beta-A does not bind C1q, so we investigated alternative mechanisms of beta-A-dependent complement activation in vitro. On incubation with normal human plasma, non-fibrillar beta-A 1-42, and truncated peptide 1-28, induced dose-dependent activation of C1s and C4, sparing C3, as assessed by densitometric analysis of immunostained membrane after SDS-PAGE and Western blotting. The mechanism of C4 activation was not dependent on C1q, because non-fibrillar beta-A can still activate C1s and C4 in plasma genetically deficient in C1q (C1qd). In Factor XII-deficient plasma (F.XIId) the amount of cleaved C4 was about 5-10% less that in C1qd and in normal EDTA plasma; the reconstitution of F.XIId plasma with physiologic concentrations of F.XII resulted in an increased (8-15%) beta-A-dependent cleavage of C4. Thus our results indicate that the C1q-independent activation of C1 and C4 can be partially mediated by the activation products of contact system. Since the activation of contact system and of C4 leads to generation of several humoral inflammatory peptides, non-fibrillar beta-A might play a role in initiating the early inflammatory reactions leading to a multistep cascade contributing to neuronal and clinical dysfunction of AD brain.
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Affiliation(s)
- L Bergamaschini
- Department of Internal Medicine, Maggiore Hospital, IRCCS, Milan, Italy.
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57
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Marx F, Blasko I, Pavelka M, Grubeck-Loebenstein B. The possible role of the immune system in Alzheimer's disease. Exp Gerontol 1998; 33:871-81. [PMID: 9951630 DOI: 10.1016/s0531-5565(98)00028-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Currently, there is little doubt that the immune system plays a role in the neurodegenerative process in Alzheimer's disease (AD). Inflammatory proteins such as complement components, enzymes, eicosanoids, and cytokines are found in association with cerebral amyloid plaques and may exacerbate the fundamental pathology of AD, by stimulating Amyloid beta (A beta) production, supporting its aggregation and increasing its cytotoxicity. Activated microglia and astrocytes are the main source of these proteins, and A beta may trigger their release. Interestingly, there are also indications that the immune system may play a protective role against the development of AD. Microglial cells have been shown to degrade A beta, and recent evidence suggests that autoreactive A beta-specific T cells may be relevant to the elimination of the peptide. This mechanism seems, however, impaired in the majority of patients with AD. The immune system seems thus to represent a natural line of defense against the accumulation of dangerous amyloidogenic substances. Impairment of this specific immunological defense mechanism and the failure to eliminate a toxic metabolite can be the basis for a chronic nonspecific inflammatory process in the brain, as described above. AD is a good example how an immune response initially aiming at maintaining the integrity of the body may fail and consequently lead to tissue destruction and neuronal loss.
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Affiliation(s)
- F Marx
- Institute for Biomedical Aging Research of the Austrian Academy of Sciences, Innsbruck, Austria
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58
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Terryberry JW, Thor G, Peter JB. Autoantibodies in neurodegenerative diseases: antigen-specific frequencies and intrathecal analysis. Neurobiol Aging 1998; 19:205-16. [PMID: 9661995 DOI: 10.1016/s0197-4580(98)00049-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The frequency of autoantibodies (AAbs) was surveyed in several neurodegenerative diseases, other neurological diseases, and controls using antigen-specific EIAs for neurofilament heavy subunit, tubulin, glial fibrillary acidic protein, S100 protein, tau, beta-amyloid peptide, myelin basic protein, and heparan sulfate proteoglycan. High frequencies of sera and cerebrospinal fluid tubulin AAbs were found in Alzheimer disease (62% and 69%, respectively), Parkinson disease (27% and 70%), amyotrophic lateral sclerosis (54% and 67%), and in sera from multiple sclerosis (50% and 67%), optic neuritis (85%), Guillain-Barré syndrome (88%), and vascular dementia (52%). High frequencies of neurofilament heavy subunit AAbs were detected in Guillain-Barré syndrome, chronic peripheral neuropathy (88%) and optic neuritis (62%); whereas, some Alzheimer's disease (33%) and vascular dementia (44%) patients had glial fibrillary acidic protein AAbs. Lower frequencies of other AAbs were found in patient groups. AAb results were also compared to functional assessment of blood-brain barrier integrity in Parkinson's disease and Alzheimer's disease. The relevance of these AAbs to pathogenesis and/or course of neurologic diseases merits further study with particular reference to subgrouping and prognosis.
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59
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Wick G, Grubeck-Loebenstein B. Primary and secondary alterations of immune reactivity in the elderly: impact of dietary factors and disease. Immunol Rev 1997; 160:171-84. [PMID: 9476675 DOI: 10.1111/j.1600-065x.1997.tb01037.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The function of the immune system declines with age. It is the aim of the present review to demonstrate that it makes sense to distinguish between primary and secondary alterations of immune reactivity in the elderly. Primary changes occur as the result of an age-dependent intrinsic decline of immune responsiveness. They also occur in healthy persons, i.e. persons selected according to the criteria of the SENIEUR protocol of the European Community's Concerted Action Program on Aging (EURAGE). T lymphocytes are hereby more severely affected than B cells or antigen presenting cells, possibly due to the involution of the thymus, which is almost complete at the age of 60. Secondary immunological changes occur as the result of environmental factors including diet, drug intake, physical activity etc. or are alternatively due to underlying diseases. In this article, the effects of high lipid intake as well as the impact of diseases, such as for instance Alzheimer's disease and atherosclerosis, will be addressed. The results underline the complexity of immunological alterations to be expected in old age. Changes in the aging immune system represent an opportunity for increased frequency and severity of disease and endanger the protective effect of vaccination.
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Affiliation(s)
- G Wick
- Institute for Biomedical Aging Research, Austrian Academy of Sciences, Innsbruck, Austria.
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60
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Cadman ED, Puttfarcken PS. Beta-amyloid peptides initiate the complement cascade without producing a comparable effect on the terminal pathway in vitro. Exp Neurol 1997; 146:388-94. [PMID: 9270049 DOI: 10.1006/exnr.1997.6540] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Activation of the classical complement cascade by beta-amyloid peptides has been hypothesized to underlie the neurodegeneration observed in Alzheimer's diseased brains. In this study, various lots of synthetic beta-amyloid peptides, A beta(1-40), A beta(1-42), and A beta(25-35), were tested for their ability to activate both early complement cascade events and formation of the membrane attack complex through terminal pathway activation. Unlike recent reports which did not assess activation of complement terminal pathway, we found that concentrations of beta-amyloid which activated early cascade events, to an extent comparable to aggregated IgG, failed to elicit formation of comparable levels of membrane attack complex.
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Affiliation(s)
- E D Cadman
- Neurological and Urological Diseases Research, Pharmaceutical Products Division, Abbott Laboratories, Abbott Park, Illinois 60064-3500, USA
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61
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Webster S, Lue LF, Brachova L, Tenner AJ, McGeer PL, Terai K, Walker DG, Bradt B, Cooper NR, Rogers J. Molecular and cellular characterization of the membrane attack complex, C5b-9, in Alzheimer's disease. Neurobiol Aging 1997; 18:415-21. [PMID: 9330973 DOI: 10.1016/s0197-4580(97)00042-0] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The membrane attack complex, C5b-9, is of considerable importance in many inflammatory reactions. It is the terminal, cytolytic component of both classical and alternative pathway activation, and its presence presupposes other potentially destructive complement constituents, including anaphylotoxins and opsonins. We have characterized C5b-9 and its C9 constituent in the Alzheimer's disease (AD) and nondemented elderly (ND) brain using immunohistochemistry at the light and electron microscopic levels, Western blot analysis, and the reverse transcriptase polymerase chain reaction. We have also conducted in vitro ELISA assays of amyloid beta-peptide-stimulated SC5b-9 production. C5b-9 is abundantly present in Alzheimer's disease cortex, associated with neurofibrillary tangle containing neurons, dystrophic neurites within neuritic plaques, and neuropil threads, but is weakly detected, if at all, in nondemented elderly cortex under the same conditions. Staining of Alzheimer's disease sections is abolished both by deletion of primary antibody or preabsorption with purified SC5b-9.
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Affiliation(s)
- S Webster
- Department of Molecular Biology and Biochemistry, University of California, Irvine 92697, USA
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62
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Rogers J, Webster S, Lue LF, Brachova L, Civin WH, Emmerling M, Shivers B, Walker D, McGeer P. Inflammation and Alzheimer's disease pathogenesis. Neurobiol Aging 1996; 17:681-6. [PMID: 8892340 DOI: 10.1016/0197-4580(96)00115-7] [Citation(s) in RCA: 299] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Appreciation of the role that inflammatory mediators play in Alzheimer's disease (AD) pathogenesis continues to be hampered by two related misconceptions. The first is that to be pathogenically significant a neurodegenerative mechanism must be primary. The second is that inflammation merely occurs to clear the detritis of already existent pathology. The present review addresses these issues by showing that 1) inflammatory molecules and mechanisms are uniquely present or significantly elevated in the AD brain, 2) inflammation may be a necessary component of AD pathogenesis, 3) inflammation may be sufficient to cause AD neurodegeneration, and 4) retrospective and direct clinical trials suggest a therapeutic benefit of conventional antiinflammatory medications in slowing the progress or even delaying the onset of AD.
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Affiliation(s)
- J Rogers
- Sun Health Research Institute, Sun City, AZ 85372, USA
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63
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Törnqvist E, Liu L, Aldskogius H, Holst HV, Svensson M. Complement and clusterin in the injured nervous system. Neurobiol Aging 1996; 17:695-705. [PMID: 8892342 DOI: 10.1016/0197-4580(96)00120-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Peripheral nerve injury and neuronal degeneration resulting from toxic ricin induce activation of the classical pathway of complement close to the injured motorneuron perikarya or sensory terminals. In contrast, degeneration of central myelinated fibers is not accompanied by complement expression. The main source of complement in peripheral nerve injury and toxic ricin degeneration appears to be microglia. Brain contusion is associated with complement activation. Some of the complement in this situation may derive from plasma, because the blood-brain barrier is disrupted. Clusterin expression is increased in astrocytes along with their activation in the vicinity of lesioned neurons. In addition, axotomized motorneurons show a marked clusterin upregulation. A relationship between clusterin and cell death is suggested by the prominent aggregation of clusterin in neuronal perikarya destroyed by the effects of toxic ricin, as well as by the neosynthesis of clusterin in apparently degenerating nonneuronal cells, presumed to be oligodendrocytes. Our findings indicate that the expression of complement and clusterin are prominent features of neural degeneration and regeneration, as it is in Alzheimer's disease brains as well. The nerve injury conditions described, therefore, offer attractive experimental models to elucidate the roles of these molecular components in neurodegenerative disorders, thereby providing useful insights into potentially new therapeutic approaches in these conditions.
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Affiliation(s)
- E Törnqvist
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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64
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Hüll M, Fiebich BL, Lieb K, Strauss S, Berger SS, Volk B, Bauer J. Interleukin-6-associated inflammatory processes in Alzheimer's disease: new therapeutic options. Neurobiol Aging 1996; 17:795-800. [PMID: 8892354 DOI: 10.1016/0197-4580(96)00107-8] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The cytokine interleukin-6 is consistently detected in the brains of Alzheimer's disease patients but not in the brains of nondemented elderly persons. Until recently it was unclear whether an interleukin-6-associated inflammatory mechanism is an early or late event in the pathological cascade of Alzheimer's disease. We investigated whether interleukin-6 could be detected in plaques of Alzheimer's disease patients prior to the onset of neuritic degeneration. We found interleukin-6 mostly in plaques where neuritic pathology has not yet developed. This indicates that the appearance of interleukin-6 may precede neuritic changes and is not just a consequence of neuritic degeneration. Therefore, one may hypothesize that activation of inflammatory mechanisms may cause neuritic degeneration in plaques. A suppression of interleukin-6 synthesis could, therefore, be of therapeutic value. Upon screening a number of substances, we found that a small number of nonsteroidal antiinflammatory drugs, including tenidap, were able to inhibit interleukin-6 synthesis in cultured human astrocytoma cells. These substances may be therapeutically useful in Alzheimer's disease and should be evaluated in clinical studies.
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Affiliation(s)
- M Hüll
- Department of Psychiatry, Freiburg University Medical School, Germany
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65
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Chen S, Frederickson RC, Brunden KR. Neuroglial-mediated immunoinflammatory responses in Alzheimer's disease: complement activation and therapeutic approaches. Neurobiol Aging 1996; 17:781-7. [PMID: 8892352 DOI: 10.1016/0197-4580(96)00103-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Increasing evidence points to A beta-containing senile plaques as primary etiological agents in Alzheimer's disease (AD). The mechanism by which these deposits cause neurotoxicity is unresolved, but there are compelling data suggesting that the activated glia found associated with senile plaques contribute to the pathology of AD. These cells appear to release a variety of immunoinflammatory molecules, including complement proteins whose activation products colocalize with senile plaques and dystrophic neurites. Previous studies showed that A beta can bind and activate complement protein C1q, providing a plausible explanation for the initiation of the complement cascade in AD. Data presented here further define the nature of A beta-C1q association, revealing key aspects of the C1q domain involved in binding the amyloid peptide. Moreover, we show that it is possible to inhibit A beta-induced complement activation without affecting the normal immunoglobulin-mediated complement pathway. This indicates that it should be feasible to develop drugs to reduce complement damage in AD without compromising this important immune-defense mechanism throughout the body.
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Affiliation(s)
- S Chen
- Gliatech Incorporated, Cleveland, OH 44122, USA
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66
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Eikelenboom P, Veerhuis R. The role of complement and activated microglia in the pathogenesis of Alzheimer's disease. Neurobiol Aging 1996; 17:673-80. [PMID: 8892339 DOI: 10.1016/0197-4580(96)00108-x] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A variety of inflammatory mediators including complement activation products, protease inhibitors, and cytokines are colocalized with beta-amyloid (A beta) deposits in the Alzeimer's disease (AD) brain. Activation products of the early complement components C1, C4, and C3 are always found in neuritic plaques and to a lesser extent in varying numbers of diffuse plaques. In contrast to these findings, no immunohistochemical evidence was obtained for the presence of the late complement components C7 and C9 and the complement membrane attack complex in the neuropathological lesions in AD brains. The mRNA encoding the late complement components C7 and C9 appears to be hardly or not detectable. These findings indicate that in AD the complement system does not act as an inflammatory mediator through membrane attack complex formation, but through the actions of the early complement products. In this review we focus on the role of complement in the pathological amyloid cascade in AD. In our opinion, the early complement activation products play a crucial role as mediators between the A beta deposits and the inflammatory responses leading to neurotoxicity.
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Affiliation(s)
- P Eikelenboom
- Graduate School Neurosciences Amsterdam, Research Institute Neurosciences Vrije Universiteit, Department of Psychiatry, Amsterdam, The Netherlands
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67
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Kalaria RN, Harshbarger-Kelly M, Cohen DL, Premkumar DR. Molecular aspects of inflammatory and immune responses in Alzheimer's disease. Neurobiol Aging 1996; 17:687-93. [PMID: 8892341 DOI: 10.1016/0197-4580(96)00114-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Recent advances indicate numerous molecular and cellular elements of the immune system are involved in the pathogenesis of Alzheimer's disease. Amyloid beta protein deposition induces many molecules associated with a predominantly local inflammatory response within the brain parenchyma. These responses also provoke the release of immune system mediators including cytokines, which all seem largely to be produced by reactive cells such as astrocytes and microglia. Classical acute phase proteins of the pentraxin and serine protease inhibitor (serpin) families as well as a host of complement proteins and some coagulation factor seem the most intrinsically involved. These secreted molecules display variable binding with the amyloidotic lesions. Although our understanding of the molecular specificity and significance of the interaction of these proteins within the lesions is not replete, the development of unique inhibitors of the inflammatory reactions could provide therapeutic strategies to impede the pathogenetic process. Currently, this appears a more viable option than to inhibit amyloid beta production or modify amyloid beta precursor protein processing, an approach which seems more complex.
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Affiliation(s)
- R N Kalaria
- Department of Neurology, Case Western Reserve University School of Medicine, Cleveland, OH 44106-4938, USA
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68
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Hüll M, Strauss S, Berger M, Volk B, Bauer J. The participation of interleukin-6, a stress-inducible cytokine, in the pathogenesis of Alzheimer's disease. Behav Brain Res 1996; 78:37-41. [PMID: 8793035 DOI: 10.1016/0166-4328(95)00213-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A loss of synapses in the cortices of demented persons appears to be the primary correlate of Alzheimer's disease (AD). However, it is still unclear how synaptic pathology is connected to other pathological findings such as neurofibrillary and neuritic degeneration or inflammatory markers in AD. Interleukin-6 (IL-6) immunoreactivity has previously been detected in plaques in the brains of AD patients. In addition, elevated IL-6 concentrations have been measured biochemically in the brains of AD patients. Since transgenic mice bearing additional copies of the IL-6 gene under the control of a brain-specific promoter develop a marked cortical pathology including severe alterations of the dendritic arborization of cortical neurons, an IL-6 related inflammatory event could well be connected to the synaptic pathology in AD. In this study, we investigated whether IL-6 immunoreactivity in plaques could already be found prior to the onset of neuritic changes, or whether the presence of this cytokine is restricted to the later stages of plaque formation. While diffuse plaques represent an early stage of plaque formation, primitive and classic plaques (displaying neuritic pathology) are thought to reflect later stages of plaque pathology. Using a silver-staining method, we classified plaque stages in serial sections of paraffin-embedded cortices of clinically diagnosed and histopathologically confirmed AD patients and of control persons with no clinical history of dementia. Adjacent sections were stained with an antibody directed against IL-6. IL-6 was detectable in a significant proportion of plaques, but only in the brains of demented patients. In the AD cases, IL-6 was found in diffuse plaques in a significantly higher ratio as would have been expected from a random distribution of IL-6 among all plaque types. This observation suggests that IL-6 expression may precede neuritic changes and that in AD an immunological mechanism may be involved both in the transformation from diffuse to primitive plaques and in the development of dementia. The reasons for the increased expression of IL-6 in the brains of AD patients are still unknown. Basal IL-6 levels were found to be slightly elevated along normal aging. Based on several studies indicating that IL-6 expression is inducible also by psychological stress, one could speculate whether long-lasting stressful experiences may contribute to the pathological process underlying Alzheimer's disease.
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Affiliation(s)
- M Hüll
- Department of Psychiatry, Freiburg University Medical School, Germany
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69
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McGeer PL, McGeer EG. The inflammatory response system of brain: implications for therapy of Alzheimer and other neurodegenerative diseases. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1995; 21:195-218. [PMID: 8866675 DOI: 10.1016/0165-0173(95)00011-9] [Citation(s) in RCA: 947] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Cultured brain cells are capable of generating many molecules associated with inflammatory and immune functions. They constitute the endogenous immune response system of brain. They include complement proteins and their regulators, inflammatory cytokines, acute phase reactants and many proteases and protease inhibitors. Most of the proteins are made by microglia and astrocytes, but even neurons are producers. Many appear in association with Alzheimer disease lesions, indicating a state of chronic inflammation in Alzheimer disease brain. Such a state can apparently exist without stimulation by peripheral inflammatory mediators or the peripheral immune system. A strong inflammatory response may be autotoxic to neurons, exacerbating the fundamental pathology in Alzheimer disease and perhaps other neurological disorders. Autotoxic processes may contribute to cellular death in chronic inflammatory diseases affecting other parts of the body, suggesting the general therapeutic value of anti-inflammatory agents. With respect to Alzheimer disease, multiple epidemiological studies indicate that patients taking anti-inflammatory drugs or suffering from conditions in which such drugs are routinely used, have a decreased risk of developing Alzheimer disease. In one very preliminary clinical trial, the anti-inflammatory drug indomethacin arrested progress of the disease. New agents directed against the inflammatory processes revealed in studies of Alzheimer disease lesions may have broad therapeutic applications.
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Affiliation(s)
- P L McGeer
- Kinsmen Laboratory of Neurological Research, University of British Columbia, Vancouver, Canada
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70
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Veerhuis R, van der Valk P, Janssen I, Zhan SS, Van Nostrand WE, Eikelenboom P. Complement activation in amyloid plaques in Alzheimer's disease brains does not proceed further than C3. Virchows Arch 1995; 426:603-10. [PMID: 7655742 DOI: 10.1007/bf00192116] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In Alzheimer's disease (AD) patients, the complement components Clq, C4 and C3 can be detected in different types of beta/A4 plaques, one of the hallmarks of AD. Contradictory findings on the presence of late complement components in AD brains have been reported. Nevertheless, it was suggested in recent studies that in AD brain complement activation results in complement membrane attack complex (MAC) formation and that complement activation may act as an intermediate between beta/A4 deposits and the neurotoxicity observed in AD. In the present study the presence of a number of complement components and regulatory proteins in AD temporal cortex and, for comparison, in glomerulonephritis (GN) was analysed. In GN kidneys, besides Clq, Clr, Cls and C3, the late components and the C5b-9 complex are also associated with capillary basement membrane and mesangial immune complex deposits. In AD temporal cortex Clq, C4 and C3 are co-localized with beta/A4 deposits. However, in contrast to the GN kidney, the late complement components C5, C7 and C9, as well as the C5b-9 membrane attack complex cannot be detected in beta/A4 positive plaques. The absence of the cytolytic C5b-9 complex in AD brain suggests that in AD, the complement MAC does not function as the proposed inflammatory mediator between beta/A4 deposits and the neurofibrillary changes.
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Affiliation(s)
- R Veerhuis
- Department of Neuropathology, Free University Hospital, Amsterdam, The Netherlands
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Oken RJ, McGeer PL. Pick's disease: possible new directions in prophylaxis and therapy. Ann Pharmacother 1995; 29:538. [PMID: 7655140 DOI: 10.1177/106002809502900515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
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72
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Yasuhara O, Matsuo A, Tooyama I, Kimura H, McGeer EG, McGeer PL. Pick's disease immunohistochemistry: new alterations and Alzheimer's disease comparisons. Acta Neuropathol 1995; 89:322-30. [PMID: 7610763 DOI: 10.1007/bf00309625] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Pick's disease (PD) brains were examined immunohistochemically for the expression of antigens known to be associated with Alzheimer's disease (AD) lesions. Most antibodies which label intracellular neurofibrillary tangles (NFTs) in AD were found to stain Pick bodies (PBs). Among them was the monoclonal antibody A2B5, which is known to recognize neuronal surface gangliosides. This result indicates that membrane proteins are probably incorporated into PBs as into NFTs. However, PBs, in contrast to NFTs, showed a paucity of staining for heparan sulfate glycosaminoglycan and basic fibroblast growth factor (bFGF). Staining for midkine, seen in senile plaques in AD, was not seen in PD. The relative lack of staining for these two neurotrophic factors in PD brain may reflect underlying mechanisms which are distinct from those in AD. We also describe two glial abnormalities in PD: glial fibrillary tangles and clusters of granules positive for the complement protein C4d in the hippocampal dentate fascia. These are presumably related to complement-activated oligodendroglia, and both pathological structures are more abundant in advanced cases, suggesting that they may be hallmarks of the disease progression.
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Affiliation(s)
- O Yasuhara
- Kinsmen Laboratory of Neurological Research, University of British Columbia, Vancouver, Canada
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