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Nimmo J, Byrne R, Daskoulidou N, Watkins L, Carpanini S, Zelek W, Morgan B. The complement system in neurodegenerative diseases. Clin Sci (Lond) 2024; 138:387-412. [PMID: 38505993 PMCID: PMC10958133 DOI: 10.1042/cs20230513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 02/15/2024] [Accepted: 03/01/2024] [Indexed: 03/21/2024]
Abstract
Complement is an important component of innate immune defence against pathogens and crucial for efficient immune complex disposal. These core protective activities are dependent in large part on properly regulated complement-mediated inflammation. Dysregulated complement activation, often driven by persistence of activating triggers, is a cause of pathological inflammation in numerous diseases, including neurological diseases. Increasingly, this has become apparent not only in well-recognized neuroinflammatory diseases like multiple sclerosis but also in neurodegenerative and neuropsychiatric diseases where inflammation was previously either ignored or dismissed as a secondary event. There is now a large and rapidly growing body of evidence implicating complement in neurological diseases that cannot be comprehensively addressed in a brief review. Here, we will focus on neurodegenerative diseases, including not only the 'classical' neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease, but also two other neurological diseases where neurodegeneration is a neglected feature and complement is implicated, namely, schizophrenia, a neurodevelopmental disorder with many mechanistic features of neurodegeneration, and multiple sclerosis, a demyelinating disorder where neurodegeneration is a major cause of progressive decline. We will discuss the evidence implicating complement as a driver of pathology in these diverse diseases and address briefly the potential and pitfalls of anti-complement drug therapy for neurodegenerative diseases.
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Affiliation(s)
- Jacqui Nimmo
- UK Dementia Research Institute Cardiff, Cardiff University, Cardiff CF24 4HQ, U.K
| | - Robert A.J. Byrne
- UK Dementia Research Institute Cardiff, Cardiff University, Cardiff CF24 4HQ, U.K
| | - Nikoleta Daskoulidou
- UK Dementia Research Institute Cardiff, Cardiff University, Cardiff CF24 4HQ, U.K
| | - Lewis M. Watkins
- UK Dementia Research Institute Cardiff, Cardiff University, Cardiff CF24 4HQ, U.K
| | - Sarah M. Carpanini
- UK Dementia Research Institute Cardiff, Cardiff University, Cardiff CF24 4HQ, U.K
| | - Wioleta M. Zelek
- UK Dementia Research Institute Cardiff, Cardiff University, Cardiff CF24 4HQ, U.K
| | - B. Paul Morgan
- UK Dementia Research Institute Cardiff, Cardiff University, Cardiff CF24 4HQ, U.K
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Zelek WM, Morgan BP. Targeting complement in neurodegeneration: challenges, risks, and strategies. Trends Pharmacol Sci 2022; 43:615-628. [DOI: 10.1016/j.tips.2022.02.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 12/13/2022]
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3
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The Complement System in the Central Nervous System: From Neurodevelopment to Neurodegeneration. Biomolecules 2022; 12:biom12020337. [PMID: 35204837 PMCID: PMC8869249 DOI: 10.3390/biom12020337] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/31/2022] [Accepted: 02/13/2022] [Indexed: 12/13/2022] Open
Abstract
The functions of the complement system to both innate and adaptive immunity through opsonization, cell lysis, and inflammatory activities are well known. In contrast, the role of complement in the central nervous system (CNS) which extends beyond immunity, is only beginning to be recognized as important to neurodevelopment and neurodegeneration. In addition to protecting the brain against invasive pathogens, appropriate activation of the complement system is pivotal to the maintenance of normal brain function. Moreover, overactivation or dysregulation may cause synaptic dysfunction and promote excessive pro-inflammatory responses. Recent studies have provided insights into the various responses of complement components in different neurological diseases and the regulatory mechanisms involved in their pathophysiology, as well as a glimpse into targeting complement factors as a potential therapeutic modality. However, there remain significant knowledge gaps in the relationship between the complement system and different brain disorders. This review summarizes recent key findings regarding the role of different components of the complement system in health and pathology of the CNS and discusses the therapeutic potential of anti-complement strategies for the treatment of neurodegenerative conditions.
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4
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Targeting Complement C3a Receptor to Improve Outcome After Ischemic Brain Injury. Neurochem Res 2021; 46:2626-2637. [PMID: 34379293 PMCID: PMC8437837 DOI: 10.1007/s11064-021-03419-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 06/30/2021] [Accepted: 07/19/2021] [Indexed: 02/08/2023]
Abstract
Ischemic stroke is a major cause of disability. No efficient therapy is currently available, except for the removal of the occluding blood clot during the first hours after symptom onset. Loss of function after stroke is due to cell death in the infarcted tissue, cell dysfunction in the peri-infarct region, as well as dysfunction and neurodegeneration in remote brain areas. Plasticity responses in spared brain regions are a major contributor to functional recovery, while secondary neurodegeneration in remote regions is associated with depression and impedes the long-term outcome after stroke. Hypoxic-ischemic encephalopathy due to birth asphyxia is the leading cause of neurological disability resulting from birth complications. Despite major progress in neonatal care, approximately 50% of survivors develop complications such as mental retardation, cerebral palsy or epilepsy. The C3a receptor (C3aR) is expressed by many cell types including neurons and glia. While there is a body of evidence for its deleterious effects in the acute phase after ischemic injury to the adult brain, C3aR signaling contributes to better outcome in the post-acute and chronic phase after ischemic stroke in adults and in the ischemic immature brain. Here we discuss recent insights into the novel roles of C3aR signaling in the ischemic brain with focus on the therapeutic opportunities of modulating C3aR activity to improve the outcome after ischemic stroke and birth asphyxia.
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Fatoba O, Itokazu T, Yamashita T. Complement cascade functions during brain development and neurodegeneration. FEBS J 2021; 289:2085-2109. [PMID: 33599083 DOI: 10.1111/febs.15772] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 02/07/2021] [Accepted: 02/16/2021] [Indexed: 12/12/2022]
Abstract
The complement system, an essential tightly regulated innate immune system, is a key regulator of normal central nervous system (CNS) development and function. However, aberrant complement component expression and activation in the brain may culminate into marked neuroinflammatory response, neurodegenerative processes and cognitive impairment. Over the years, complement-mediated neuroinflammatory responses and complement-driven neurodegeneration have been increasingly implicated in the pathogenesis of a wide spectrum of CNS disorders. This review describes how complement system contributes to normal brain development and function. We also discuss how pathologic insults such as misfolded proteins, lipid droplet/lipid droplet-associated protein or glycosaminoglycan accumulation could trigger complement-mediated neuroinflammatory responses and neurodegenerative process in neurodegenerative proteinopathies, age-related macular degeneration and neurodegenerative lysosomal storage disorders.
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Affiliation(s)
- Oluwaseun Fatoba
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Suita, Japan.,WPI-Immunology Frontier Research Center, Osaka University, Suita, Japan
| | - Takahide Itokazu
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Suita, Japan.,Department of Neuro-Medical Science, Graduate School of Medicine, Osaka University, Suita, Japan
| | - Toshihide Yamashita
- Department of Molecular Neuroscience, Graduate School of Medicine, Osaka University, Suita, Japan.,WPI-Immunology Frontier Research Center, Osaka University, Suita, Japan.,Department of Neuro-Medical Science, Graduate School of Medicine, Osaka University, Suita, Japan
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6
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Morgan BP, Gommerman JL, Ramaglia V. An "Outside-In" and "Inside-Out" Consideration of Complement in the Multiple Sclerosis Brain: Lessons From Development and Neurodegenerative Diseases. Front Cell Neurosci 2021; 14:600656. [PMID: 33488361 PMCID: PMC7817777 DOI: 10.3389/fncel.2020.600656] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 11/24/2020] [Indexed: 12/14/2022] Open
Abstract
The last 15 years have seen an explosion of new findings on the role of complement, a major arm of the immune system, in the central nervous system (CNS) compartment including contributions to cell migration, elimination of synapse during development, aberrant synapse pruning in neurologic disorders, damage to nerve cells in autoimmune diseases, and traumatic injury. Activation of the complement system in multiple sclerosis (MS) is typically thought to occur as part of a primary (auto)immune response from the periphery (the outside) against CNS antigens (the inside). However, evidence of local complement production from CNS-resident cells, intracellular complement functions, and the more recently discovered role of early complement components in shaping synaptic circuits in the absence of inflammation opens up the possibility that complement-related sequelae may start and finish within the brain itself. In this review, the complement system will be introduced, followed by evidence that implicates complement in shaping the developing, adult, and normal aging CNS as well as its contribution to pathology in neurodegenerative conditions. Discussion of data supporting "outside-in" vs. "inside-out" roles of complement in MS will be presented, concluded by thoughts on potential approaches to therapies targeting specific elements of the complement system.
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Affiliation(s)
- B. Paul Morgan
- UK Dementia Research Institute at Cardiff, Cardiff University, Cardiff, United Kingdom
| | | | - Valeria Ramaglia
- Department of Immunology, University of Toronto, Toronto, ON, Canada
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Le Fournis C, Jeanneau C, Roumani S, Giraud T, About I. Pulp Fibroblast Contribution to the Local Control of Pulp Inflammation via Complement Activation. J Endod 2020; 46:S26-S32. [PMID: 32950192 DOI: 10.1016/j.joen.2020.06.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Upon traumatic injuries or carious lesions, the elimination of bacteria infiltrating the pulp is recognized as a prerequisite for initiating the regeneration process. Complement is a major system involved in initiating the inflammatory reaction and the subsequent bacteria elimination. This plasma system of above 35 proteins is synthesized by the liver and some immune cells. It is activated by 3 pathways: the classical, alternative, and lectin pathways that can be triggered by physical injuries, infection, and biomaterials. Recent data have shown that the pulp fibroblast represents a unique nonimmune cell type able to synthesize Complement proteins. Indeed, after physical injuries/bacteria stimulation, the pulp fibroblast has been shown to synthesize and to activate the complement system leading to the production of biologically active molecules such as C5a, C3b, and the membrane attack complex. This local secretion represents a rapid and efficient mechanism for eliminating bacteria invading the pulp, thus supporting complement activation from the plasma. Pulp fibroblast-secreted Complement proteins allow cariogenic bacteria direct lysis via membrane attack complex formation on their surface, phagocytic cell recruitment by producing C5a and cariogenic bacteria opsonization by C3b fixation on their surface, stimulating cariogenic bacteria phagocytosis. Overall, this review highlights that, in addition to initiating the inflammatory reaction, pulp fibroblasts also provide a powerful control of this inflammation via local Complement activation. The pathogen elimination capacity by fibroblast-produced complement demonstrates that this system is a strong local actor in arresting bacterial progression into the dental pulp.
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Affiliation(s)
- Chloé Le Fournis
- Aix-Marseille University, Centre National de la Recherche Scientifique, Institut des Sciences du Mouvement, Marseille, France
| | - Charlotte Jeanneau
- Aix-Marseille University, Centre National de la Recherche Scientifique, Institut des Sciences du Mouvement, Marseille, France
| | - Sandra Roumani
- Aix-Marseille University, Centre National de la Recherche Scientifique, Institut des Sciences du Mouvement, Marseille, France
| | - Thomas Giraud
- Aix-Marseille University, Centre National de la Recherche Scientifique, Institut des Sciences du Mouvement, Marseille, France; Assistance Publique-Hôpitaux de Marseille, Hôpital Timone, Service d'Odontologie, Marseille, France
| | - Imad About
- Aix-Marseille University, Centre National de la Recherche Scientifique, Institut des Sciences du Mouvement, Marseille, France.
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Reichhardt MP, Meri S. Intracellular complement activation-An alarm raising mechanism? Semin Immunol 2018; 38:54-62. [PMID: 29631809 DOI: 10.1016/j.smim.2018.03.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 03/26/2018] [Indexed: 12/20/2022]
Abstract
It has become increasingly apparent that the complement system, being an ancient defense mechanism, is not operative only in the extracellular milieu but also intracellularly. In addition to the known synthetic machinery in the liver and by macrophages, many other cell types, including lymphocytes, adipocytes and epithelial cells produce selected complement components. Activation of e.g. C3 and C5 inside cells may have multiple effects ranging from direct antimicrobial defense to cell differentiation and possible influence on metabolism. Intracellular activation of C3 and C5 in T cells is involved in the maintenance of immunological tolerance and promotes differentiation of T helper cells into Th1-type cells that activate cell-mediated immune responses. Adipocytes are unique in producing many complement sensor proteins (like C1q) and Factor D (adipsin), the key enzyme in promoting alternative pathway amplification. The effects of complement activation products are mediated by intracellular and cell membrane receptors, like C3aR, C5aR1, C5aR2 and the complement regulator MCP/CD46, often jointly with other receptors like the T cell receptor, Toll-like receptors and those of the inflammasomes. These recent observations link complement activation to cellular metabolic processes, intracellular defense reactions and to diverse adaptive immune responses. The complement components may thus be viewed as intracellular alarm molecules involved in the cellular danger response.
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Affiliation(s)
- M P Reichhardt
- Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom.
| | - S Meri
- Department of Bacteriology and Immunology, Haartman Institute, Immunobiology Research Program, University of Helsinki, Helsinki, Finland; Helsinki University Central Hospital Laboratory (HUSLAB), Helsinki, Finland.
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9
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Neuroprotective effect of mesenchymal stem cell through complement component 3 downregulation after transient focal cerebral ischemia in mice. Neurosci Lett 2016; 633:227-234. [DOI: 10.1016/j.neulet.2016.09.032] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Revised: 09/17/2016] [Accepted: 09/20/2016] [Indexed: 12/14/2022]
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10
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Karch CM, Goate AM. Alzheimer's disease risk genes and mechanisms of disease pathogenesis. Biol Psychiatry 2015; 77:43-51. [PMID: 24951455 PMCID: PMC4234692 DOI: 10.1016/j.biopsych.2014.05.006] [Citation(s) in RCA: 839] [Impact Index Per Article: 93.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2013] [Revised: 04/30/2014] [Accepted: 05/05/2014] [Indexed: 01/18/2023]
Abstract
We review the genetic risk factors for late-onset Alzheimer's disease (AD) and their role in AD pathogenesis. More recent advances in understanding of the human genome-technologic advances in methods to analyze millions of polymorphisms in thousands of subjects-have revealed new genes associated with AD risk, including ABCA7, BIN1, CASS4, CD33, CD2AP, CELF1, CLU, CR1, DSG2, EPHA1, FERMT2, HLA-DRB5-DBR1, INPP5D, MS4A, MEF2C, NME8, PICALM, PTK2B, SLC24H4-RIN3, SORL1, and ZCWPW1. Emerging technologies to analyze the entire genome in large data sets have also revealed coding variants that increase AD risk: PLD3 and TREM2. We review the relationship between these AD risk genes and the cellular and neuropathologic features of AD. Understanding the mechanisms underlying the association of these genes with risk for disease will provide the most meaningful targets for therapeutic development to date.
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Affiliation(s)
| | - Alison M. Goate
- Corresponding author Contact information: Department of Psychiatry, Washington University School of Medicine, 425 S. Euclid Ave, Campus Box 8134, St. Louis, MO 63110, phone: 314-362-8691, fax: 314-747-2983,
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11
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Moore RA, Sturdevant DE, Chesebro B, Priola SA. Proteomics analysis of amyloid and nonamyloid prion disease phenotypes reveals both common and divergent mechanisms of neuropathogenesis. J Proteome Res 2014; 13:4620-34. [PMID: 25140793 PMCID: PMC4227561 DOI: 10.1021/pr500329w] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
![]()
Prion
diseases are a heterogeneous group of neurodegenerative disorders
affecting various mammals including humans. Prion diseases are characterized
by a misfolding of the host-encoded prion protein (PrPC) into a pathological isoform termed PrPSc. In wild-type
mice, PrPC is attached to the plasma membrane by a glycosylphosphatidylinositol
(GPI) anchor and PrPSc typically accumulates in diffuse
nonamyloid deposits with gray matter spongiosis. By contrast, when
mice lacking the GPI anchor are infected with the same prion inoculum,
PrPSc accumulates in dense perivascular amyloid plaques
with little or no gray matter spongiosis. In order to evaluate whether
different host biochemical pathways were implicated in these two phenotypically
distinct prion disease models, we utilized a proteomics approach.
In both models, infected mice displayed evidence of a neuroinflammatory
response and complement activation. Proteins involved in cell death
and calcium homeostasis were also identified in both phenotypes. However,
mitochondrial pathways of apoptosis were implicated only in the nonamyloid
form, whereas metal binding and synaptic vesicle transport were more
disrupted in the amyloid phenotype. Thus, following infection with
a single prion strain, PrPC anchoring to the plasma membrane
correlated not only with the type of PrPSc deposition but
also with unique biochemical pathways associated with pathogenesis.
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Affiliation(s)
- Roger A Moore
- Laboratory of Persistent Viral Diseases and ‡Research Technologies Branch, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases , Hamilton, Montana 59840, United States
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12
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Neal JW. Flaviviruses are neurotropic, but how do they invade the CNS? J Infect 2014; 69:203-15. [PMID: 24880028 DOI: 10.1016/j.jinf.2014.05.010] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2014] [Revised: 05/10/2014] [Accepted: 05/19/2014] [Indexed: 12/17/2022]
Abstract
Flaviruses (FV) are RNA viruses carried by mosquitoes. Neurological signs including acute encephalitis, meningitis and acute flaccid paralysis develop in a small percentage of infected individuals; long term sequlae are, Parkinsonism, dystonias and cognitive changes. FV neuroinfection is neurotropic involving subcortical nuclei (substantia nigra and thalamus) anterior horn neurons and neocortex. Glycosylation of the FV E envelope protein is one determinant of neuroinvasion, increasing both axonal and trans-epithelial transportation. Neutralizing antibodies against the E and NS proteins prevents FV uptake into several cell types, including axons. CD8+ T cells are vital for clearance of WNF infected cells from the CNS, whereas TLR-3 and TLR-7 mediated anti-virus response through increased serum inflammatory cytokines to disrupt the BBB providing infected leucocytes and free virus access to the CNS (so called Trojan horse) Cellular virus attachment factors, promoting FV cell entry are widely distributed and include DC-SIGN (that detects complex carbohydrate molecules); Glycosamino glycans (GAG), Heparan sulphate(HSPG) Semaphorin 7A, Low Density Lipid receptors (LDLR); these are not FV specific virus entry receptors. The FV also crosses epithelial and endothelial barriers by disrupting Tight Junction complexes to increase BBB permeability. This review describes the multiple pathways responsible for the neuroinvasive properties of the Flaviviruses.
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Affiliation(s)
- J W Neal
- Institute of Infection and Immunity, Henry Wellcome Building, University Hospital of Wales, Cardiff University, Cardiff CF14 4XN, United Kingdom.
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Shen Y, Yang L, Li R. What does complement do in Alzheimer's disease? Old molecules with new insights. Transl Neurodegener 2013; 2:21. [PMID: 24119446 PMCID: PMC3853043 DOI: 10.1186/2047-9158-2-21] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 10/01/2013] [Indexed: 11/25/2022] Open
Abstract
Increasing evidence suggests that inflammatory and immune components in brain are important in Alzheimer's disease (AD) and anti-inflammatory and immunotherapeutic approaches may be amenable to AD treatment. It is known that complement activation occurs in the brain of patients with AD, and contributes to a local inflammatory state development which is correlated with cognitive impairment. In addition to the complement's critical role in the innate immune system recognizing and killing, or targeting for destruction, complement proteins can also interact with cell surface receptors to promote a local inflammatory response and contributes to the protection and healing of the host. On the other hand, complement activation also causes inflammation and cell damage as an essential immune function to eliminate cell debris and potentially toxic protein aggregates. It is the balance of these seemingly competing events that influences the ultimate state of neuronal function. Our mini review will be focusing on the unique molecular interactions happening in the AD development, the functional outcomes of those interactions, as well as the contribution of each element to AD.
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Affiliation(s)
- Yong Shen
- Center for Advanced Therapeutic Strategies for Brain Disorders, Roskamp Institute, 2040 Whitfield Avenue, Sarasota, USA
- Department of Neurology, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Libang Yang
- Department of Pediatrics, School of Medicine, University of Minnesota, Minneapolis, MN 55455, USA
| | - Rena Li
- Center for Hormones Advanced Science and Education, Roskamp Institute, 2040 Whitfield Avenue, Sarasota, Florida, USA
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14
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How does the brain limit the severity of inflammation and tissue injury during bacterial meningitis? J Neuropathol Exp Neurol 2013; 72:370-85. [PMID: 23584204 DOI: 10.1097/nen.0b013e3182909f2f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The most devastating CNS bacterial infection, bacterial meningitis, has both acute and long-term neurologic consequences. The CNS defends itself against bacterial invasion through a combination of physical barriers (i.e. blood-brain barrier, meninges, and ependyma), which contain macrophages that express a range of pattern-recognition receptors that detect pathogens before they gain access to the CNS and cerebrospinal fluid. This activates an antipathogen response consisting of inflammatory cytokines, complement, and chemoattractants. Regulation of the antipathogen inflammatory response is essential for preventing irreversible brain injury and protecting stem cell populations in the ventricle wall. The severity of brain inflammation is regulated by the clearance of apoptotic inflammatory cells and neurons. Death signaling pathways are expressed by glia to stimulate apoptosis of neutrophils, lymphocytes, and damaged neurons and to regulate in flammation and remove necrotic cells. The emerging group of neuroimmunoregulatory molecules adjusts the balance of the anti-inflammatory and proinflammatory response to provide optimal conditions for effective clearance of pathogens and apoptotic cells but reduce the severity of the inflammatory response to prevent injury to brain cells, including stem cell populations. The neuroimmunoregulatory molecules and other CNS anti-inflammatory pathways represent potential therapeutic targets capable of reducing brain injury caused by bacterial infection.
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Microglia, Alzheimer's disease, and complement. Int J Alzheimers Dis 2012; 2012:983640. [PMID: 22957298 PMCID: PMC3432348 DOI: 10.1155/2012/983640] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 05/01/2012] [Accepted: 05/07/2012] [Indexed: 02/02/2023] Open
Abstract
Microglia, the immune cell of the brain, are implicated in cascades leading to neuronal loss and cognitive decline in Alzheimer's disease (AD). Recent genome-wide association studies have indicated a number of risk factors for the development of late-onset AD. Two of these risk factors are an altered immune response and polymorphisms in complement receptor 1. In view of these findings, we discuss how complement signalling in the AD brain and microglial responses in AD intersect. Dysregulation of the complement cascade, either by changes in receptor expression, enhanced activation of different complement pathways or imbalances between complement factor production and complement cascade inhibitors may all contribute to the involvement of complement in AD. Altered complement signalling may reduce the ability of microglia to phagocytose apoptotic cells and clear amyloid beta peptides, modulate the expression by microglia of complement components and receptors, promote complement factor production by plaque-associated cytokines derived from activated microglia and astrocytes, and disrupt complement inhibitor production. The evidence presented here indicates that microglia in AD are influenced by complement factors to adopt protective or harmful phenotypes and the challenge ahead lies in understanding how this can be manipulated to therapeutic advantage to treat late onset AD.
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Ingram G, Hakobyan S, Hirst CL, Harris CL, Loveless S, Mitchell JP, Pickersgill TP, Robertson NP, Morgan BP. Systemic complement profiling in multiple sclerosis as a biomarker of disease state. Mult Scler 2012; 18:1401-11. [PMID: 22354735 PMCID: PMC3697901 DOI: 10.1177/1352458512438238] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND There is increasing evidence of significant and dynamic systemic activation and upregulation of complement in multiple sclerosis (MS), which may contribute to disease pathogenesis. OBJECTIVE We aimed to investigate the pathological role of complement in MS and the potential role for complement profiling as a biomarker of MS disease state. METHODS Key components of the classical, alternative and terminal pathways of complement were measured in plasma and cerebrospinal fluid (CSF) of patients with MS in different clinical phases of disease and in matched controls. RESULTS Increased plasma levels of C3 (p<0.003), C4 (p<0.001), C4a (p<0.001), C1 inhibitor (p<0.001), and factor H (p<0.001), and reduced levels of C9 (p<0.001) were observed in MS patients compared with controls. Combined profiling of these analytes produced a statistical model with a predictive value of 97% for MS and 73% for clinical relapse when combined with selected demographic data. CSF-plasma correlations suggested that source of synthesis of these components was both systemic and central. CONCLUSION These data provide further evidence of alterations in both local and systemic expression and activation of complement in MS and suggest that complement profiling may be informative as a biomarker of MS disease, although further work is needed to determine its use in distinguishing MS from its differential.
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Affiliation(s)
- G Ingram
- Department of Neurology, University Hospital of Wales, Cardiff, UK
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Fraczek LA, Martin CB, Martin BK. c-Jun and c-Fos regulate the complement factor H promoter in murine astrocytes. Mol Immunol 2011; 49:201-10. [PMID: 21920606 DOI: 10.1016/j.molimm.2011.08.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2011] [Revised: 08/08/2011] [Accepted: 08/18/2011] [Indexed: 11/24/2022]
Abstract
The complement system is a critical component of innate immunity that requires regulation to avoid inappropriate activation. This regulation is provided by many proteins, including complement factor H (CFH), a critical regulator of the alternative pathway of complement activation. Given its regulatory function, mutations in CFH have been implicated in diseases such as age-related macular degeneration and membranoproliferative glomerulonephritis, and central nervous system diseases such as Alzheimer's disease, Parkinson's disease, and a demyelinating murine model, experimental autoimmune encephalomyelitis (EAE). There have been few investigations on the transcriptional regulation of CFH in the brain and CNS. Our studies show that CFH mRNA is present in several CNS cell types. The murine CFH (mCFH) promoter was cloned and examined through truncation constructs and we show that specific regions throughout the promoter contain enhancers and repressors that are positively regulated by inflammatory cytokines in astrocytes. Database mining of these regions indicated transcription factor binding sites conserved between different species, which led to the investigation of specific transcription factor binding interactions in a 241 base pair (bp) region at -416 bp to -175 bp that showed the strongest activity. Through supershift analysis, it was determined that c-Jun and c-Fos interact with the CFH promoter in astrocytes in this region. These results suggest a relationship between cell cycle and complement regulation, and how these transcription factors and CFH affect disease will be a valuable area of investigation.
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Affiliation(s)
- Laura A Fraczek
- Interdisciplinary Program in Immunology, University of Iowa, Iowa City, IA 52242, United States
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Haque R, Hwang BY, Appelboom G, Piazza MA, Guo K, Connolly ES. Alterations in systemic complement component 3a and 5a levels in patients with cerebral arteriovenous malformations. J Clin Neurosci 2011; 18:1235-9. [DOI: 10.1016/j.jocn.2011.02.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 02/27/2011] [Indexed: 10/18/2022]
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Crehan H, Holton P, Wray S, Pocock J, Guerreiro R, Hardy J. Complement receptor 1 (CR1) and Alzheimer's disease. Immunobiology 2011; 217:244-50. [PMID: 21840620 DOI: 10.1016/j.imbio.2011.07.017] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 06/22/2011] [Accepted: 07/17/2011] [Indexed: 01/14/2023]
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disease and it poses an ever-increasing burden to an aging population. Several loci responsible for the rare, autosomal dominant form of AD have been identified (APP, PS1 and PS2), and these have facilitated the development of the amyloid cascade hypothesis of AD aetiology. The late onset form of the disease (LOAD) is poorly defined genetically, and up until recently the only known risk factor was the ε4 allele of APOE. Recent genome-wide association studies (GWAS) have identified common genetic variants that increase risk of LOAD. Two of the genes highlighted in these studies, CLU and CR1, suggest a role for the complement system in the aetiology of AD. In this review we analyse the evidence for an involvement of complement in AD. In particular we focus on one gene, CR1, and its role in the complement cascade. CR1 is a receptor for the complement fragments C3b and C4b and is expressed on many different cell types, particularly in the circulatory system. We look at the evidence for genetic polymorphisms in the gene and the possible physiological effects of these well-documented changes. Finally, we discuss the possible impact of CR1 genetic polymorphisms in relation to the amyloid cascade hypothesis of AD and the way in which CR1 may lead to AD pathogenesis.
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Affiliation(s)
- Helen Crehan
- Reta Lila Weston Laboratories and Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, London, United Kingdom
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20
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Veerhuis R, Nielsen HM, Tenner AJ. Complement in the brain. Mol Immunol 2011; 48:1592-603. [PMID: 21546088 DOI: 10.1016/j.molimm.2011.04.003] [Citation(s) in RCA: 289] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 04/04/2011] [Accepted: 04/04/2011] [Indexed: 01/24/2023]
Abstract
The brain is considered to be an immune privileged site, because the blood-brain barrier limits entry of blood borne cells and proteins into the central nervous system (CNS). As a result, the detection and clearance of invading microorganisms and senescent cells as well as surplus neurotransmitters, aged and glycated proteins, in order to maintain a healthy environment for neuronal and glial cells, is largely confined to the innate immune system. In recent years it has become clear that many factors of innate immunity are expressed throughout the brain. Neuronal and glial cells express Toll like receptors as well as complement receptors, and virtually all complement components can be locally produced in the brain, often in response to injury or developmental cues. However, as inflammatory reactions could interfere with proper functioning of the brain, tight and fine tuned regulatory mechanisms are warranted. In age related diseases, such as Alzheimer's disease (AD), accumulating amyloid proteins elicit complement activation and a local, chronic inflammatory response that leads to attraction and activation of glial cells that, under such activation conditions, can produce neurotoxic substances, including pro-inflammatory cytokines and oxygen radicals. This process may be exacerbated by a disturbed balance between complement activators and complement regulatory proteins such as occurs in AD, as the local synthesis of these proteins is differentially regulated by pro-inflammatory cytokines. Much knowledge about the role of complement in neurodegenerative diseases has been derived from animal studies with transgenic overexpressing or knockout mice for specific complement factors or receptors. These studies have provided insight into the potential therapeutic use of complement regulators and complement receptor antagonists in chronic neurodegenerative diseases as well as in acute conditions, such as stroke. Interestingly, recent animal studies have also indicated that complement activation products are involved in brain development and synapse formation. Not only are these findings important for the understanding of how brain development and neural network formation is organized, it may also give insights into the role of complement in processes of neurodegeneration and neuroprotection in the injured or aged and diseased adult central nervous system, and thus aid in identifying novel and specific targets for therapeutic intervention.
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Affiliation(s)
- Robert Veerhuis
- Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands.
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Griffiths MR, Gasque P, Neal JW. The regulation of the CNS innate immune response is vital for the restoration of tissue homeostasis (repair) after acute brain injury: a brief review. Int J Inflam 2010; 2010:151097. [PMID: 21152121 PMCID: PMC2989866 DOI: 10.4061/2010/151097] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Revised: 01/06/2010] [Accepted: 04/28/2010] [Indexed: 12/12/2022] Open
Abstract
Neurons and glia respond to acute injury by participating in the CNS innate immune response. This involves the recognition and clearance of "not self " pathogens and "altered self " apoptotic cells. Phagocytic receptors (CD14, CD36, TLR-4) clear "not self" pathogens; neurons and glia express "death signals" to initiate apoptosis in T cells.The complement opsonins C1q, C3, and iC3b facilitate the clearance of apoptotic cells by interacting with CR3 and CR4 receptors. Apoptotic cells are also cleared by the scavenger receptors CD14, Prs-R, TREM expressed by glia. Serpins also expressed by glia counter the neurotoxic effects of thrombin and other systemic proteins that gain entry to the CNS following injury. Complement pathway and T cell activation are both regulated by complement regulatory proteins expressed by glia and neurons. CD200 and CD47 are NIRegs expressed by neurons as "don't eat me" signals and they inhibit microglial activity preventing host cell attack. Neural stem cells regulate T cell activation, increase the Treg population, and suppress proinflammatory cytokine expression. Stem cells also interact with the chemoattractants C3a, C5a, SDF-1, and thrombin to promote stem cell migration into damaged tissue to support tissue homeostasis.
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Affiliation(s)
- M. R. Griffiths
- Deptartment of Medical Biochemistry, University Hospital of Wales, Cardiff University Medical School, Cardiff CF14 4XN, UK
| | - P. Gasque
- Deptartment of Medical Biochemistry, University Hospital of Wales, Cardiff University Medical School, Cardiff CF14 4XN, UK
- University Labo. Biochimie et Genetique Moleculaire, Facilities de Science et Technologies, Universite de La Reunion, 15 Avenue Rene Cassin Saint Denis, Ile de la Reunion, BP 7151, 97715, France
| | - J. W. Neal
- Deptartment of Histopathology, University Hospital of Wales, Cardiff University Medical School, Cardiff CF14 4XN, UK
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22
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Abstract
The complement (C) system plays a central role in innate immunity and bridges innate and adaptive immune responses. A fine balance of C activation and regulation mediates the elimination of invading pathogens and the protection of the host from excessive C deposition on healthy tissues. If this delicate balance is disrupted, the C system may cause injury and contribute to the pathogenesis of various diseases, including neurodegenerative disorders and neuropathies. Here we review evidence indicating that C factors and regulators are locally synthesized in the nervous system and we discuss the evidence supporting the protective or detrimental role of C activation in health, injury, and disease of the nerve.
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Affiliation(s)
- V Ramaglia
- Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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23
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Woodruff TM, Ager RR, Tenner AJ, Noakes PG, Taylor SM. The role of the complement system and the activation fragment C5a in the central nervous system. Neuromolecular Med 2009; 12:179-92. [PMID: 19763906 DOI: 10.1007/s12017-009-8085-y] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 08/25/2009] [Indexed: 12/28/2022]
Abstract
The complement system is a pivotal component of the innate immune system which protects the host from infection and injury. Complement proteins can be induced in all cell types within the central nervous system (CNS), where the pathway seems to play similar roles in host defense. Complement activation produces the C5 cleavage fragment C5a, a potent inflammatory mediator, which recruits and activates immune cells. The primary cellular receptor for C5a, the C5a receptor (CD88), has been reported to be on all CNS cells, including neurons and glia, suggesting a functional role for C5a in the CNS. A second receptor for C5a, the C5a-like receptor 2 (C5L2), is also expressed on these cells; however, little is currently known about its potential role in the CNS. The potent immune and inflammatory actions of complement activation are necessary for host defense. However, if over-activated, or left unchecked it promotes tissue injury and contributes to brain disease pathology. Thus, complement activation, and subsequent C5a generation, is thought to play a significant role in the progression of CNS disease. Paradoxically, complement may also exert a neuroprotective role in these diseases by aiding in the elimination of aggregated and toxic proteins and debris which are a principal hallmark of many of these diseases. This review will discuss the expression and known roles for complement in the CNS, with a particular focus on the pro-inflammatory end-product, C5a. The possible overarching role for C5a in diseases of the CNS is reviewed, and the therapeutic potential of blocking C5a/CD88 interaction is evaluated.
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Affiliation(s)
- Trent M Woodruff
- School of Biomedical Sciences, University of Queensland, St. Lucia, Brisbane, 4072, Australia.
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24
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Griffiths MR, Neal JW, Fontaine M, Das T, Gasque P. Complement factor H, a marker of self protects against experimental autoimmune encephalomyelitis. THE JOURNAL OF IMMUNOLOGY 2009; 182:4368-77. [PMID: 19299737 DOI: 10.4049/jimmunol.0800205] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The CNS innate immune response is a "double-edged sword" representing a fine balance between protective antipathogen responses and detrimental neurocytotoxic effects. Hence, it is important to identify the key regulatory mechanisms involved in the control of CNS innate immunity and which could be harnessed to explore novel therapeutic avenues. In analogy to the newly described neuroimmune regulatory proteins also known as "don't eat me" signals (CD200, CD47, CD22, fractalkine, semaphorins), we herein identify the key role of complement regulator factor H (fH) in controlling neuroinflammation initiated in an acute mouse model of Ab-dependent experimental autoimmune encephalomyelitis. Mouse fH was found to be abundantly expressed by primary cultured neurons and neuronal cell lines (N1E115 and Neuro2a) at a level comparable to BV2 microglia and CLTT astrocytes. Mouse neurons expressed other complement regulators crry and low levels of CD55. In the brain, the expression of fH was localized to neuronal bodies and axons, endothelial cells, microglia but not oligodendrocytes and myelin sheaths and was dramatically reduced in inflammatory experimental autoimmune encephalomyelitis settings. When exogenous human fH was administered to disease Ab-dependent experimental autoimmune encephalomyelitis animals, there was a significant decrease in clinical score, inflammation, and demyelination, as compared with PBS-injected animals. We found that the accumulation of human fH in the brain parenchyma protected neurons from complement opsonization, axonal injury, and leukocyte infiltration. Our data argue for a key regulatory activity of fH in neuroprotection and provide novel therapeutic avenues for CNS chronic inflammatory diseases.
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Affiliation(s)
- Mark R Griffiths
- Department of Medical Biochemistry, Cardiff University, United Kingdom
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25
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Färber K, Cheung G, Mitchell D, Wallis R, Weihe E, Schwaeble W, Kettenmann H. C1q, the recognition subcomponent of the classical pathway of complement, drives microglial activation. J Neurosci Res 2009; 87:644-52. [PMID: 18831010 DOI: 10.1002/jnr.21875] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Microglia, central nervous system (CNS) resident phagocytic cells, persistently police the integrity of CNS tissue and respond to any kind of damage or pathophysiological changes. These cells sense and rapidly respond to danger and inflammatory signals by changing their cell morphology; by release of cytokines, chemokines, or nitric oxide; and by changing their MHC expression profile. We have shown previously that microglial biosynthesis of the complement subcomponent C1q may serve as a reliable marker of microglial activation ranging from undetectable levels of C1q biosynthesis in resting microglia to abundant C1q expression in activated, nonramified microglia. In this study, we demonstrate that cultured microglial cells respond to extrinsic C1q with a marked intracellular Ca(2+) increase. A shift toward proinflammatory microglial activation is indicated by the release of interleukin-6, tumor necrosis factor-alpha, and nitric oxide and the oxidative burst in rat primary microglial cells, an activation and differentiation process similar to the proinflammatory response of microglia to exposure to lipopolysaccharide. Our findings indicate 1) that extrinsic plasma C1q is involved in the initiation of microglial activation in the course of CNS diseases with blood-brain barrier impairment and 2) that C1q synthesized and released by activated microglia is likely to contribute in an autocrine/paracrine way to maintain and balance microglial activation in the diseased CNS tissue.
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Affiliation(s)
- Katrin Färber
- Cellular Neuroscience, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
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26
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Trouw LA, Nielsen HM, Minthon L, Londos E, Landberg G, Veerhuis R, Janciauskiene S, Blom AM. C4b-binding protein in Alzheimer's disease: Binding to Aβ1–42 and to dead cells. Mol Immunol 2008; 45:3649-60. [DOI: 10.1016/j.molimm.2008.04.025] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Revised: 04/23/2008] [Accepted: 04/24/2008] [Indexed: 11/16/2022]
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27
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Gaultier A, Arandjelovic S, Niessen S, Overton CD, Linton MF, Fazio S, Campana WM, Cravatt BF, Gonias SL. Regulation of tumor necrosis factor receptor-1 and the IKK-NF-kappaB pathway by LDL receptor-related protein explains the antiinflammatory activity of this receptor. Blood 2008; 111:5316-25. [PMID: 18369152 PMCID: PMC2396725 DOI: 10.1182/blood-2007-12-127613] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2007] [Accepted: 03/18/2008] [Indexed: 12/18/2022] Open
Abstract
Low-density lipoprotein receptor-related protein (LRP-1) functions in endocytosis and in cell signaling directly (by binding signaling adaptor proteins) or indirectly (by regulating levels of other cell-surface receptors). Because recent studies in rodents suggest that LRP-1 inhibits inflammation, we conducted activity-based protein profiling experiments to discover novel proteases, involved in inflammation, that are regulated by LRP-1. We found that activated complement proteases accumulate at increased levels when LRP-1 is absent. Although LRP-1 functions as an endocytic receptor for C1r and C1s, complement protease mRNA expression was increased in LRP-1-deficient cells, as was expression of inducible nitric oxide synthase (iNOS) and interleukin-6. Regulation of expression of inflammatory mediators was explained by the ability of LRP-1 to suppress basal cell signaling through the I kappaB kinase-nuclear factor-kappaB (NF-kappaB) pathway. LRP-1-deficient macrophages, isolated from mice, demonstrated increased expression of iNOS, C1r, and monocyte chemoattractant protein-1 (MCP-1); MCP-1 expression was inhibited by NF-kappaB antagonism. The mechanism by which LRP-1 inhibits NF-kappaB activity involves down-regulating cell-surface tumor necrosis factor receptor-1 (TNFR1) and thus, inhibition of autocrine TNFR1-initiated cell signaling. TNF-alpha-neutralizing antibody inhibited NF-kappaB activity selectively in LRP-1-deficient cells. We propose that LRP-1 suppresses expression of inflammatory mediators indirectly, by regulating TNFR1-dependent cell signaling through the I kappaB kinase-NF-kappaB pathway.
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Affiliation(s)
- Alban Gaultier
- Department of Pathology, University of California San Diego School of Medicine, La Jolla, CA 92093-0612, USA
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28
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29
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Li K, Sacks SH, Zhou W. The relative importance of local and systemic complement production in ischaemia, transplantation and other pathologies. Mol Immunol 2007; 44:3866-74. [PMID: 17768105 DOI: 10.1016/j.molimm.2007.06.006] [Citation(s) in RCA: 122] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2007] [Indexed: 10/22/2022]
Abstract
Besides a critical role in innate host defence, complement activation contributes to inflammatory and immunological responses in a number of pathological conditions. Many tissues outside the liver (the primary source of complement) synthesise a variety of complement proteins, either constitutively or response to noxious stimuli. The significance of this local synthesis of complement has become clearer as a result of functional studies. It revealed that local production not only contributes to the systemic pool of complement but also influences local tissue injury and provides a link with the antigen-specific immune response. Extravascular production of complement seems particularly important at locations with poor access to circulating components and at sites of tissue stress responses, notably portals of entry of invasive microbes, such as interstitial spaces and renal tubular epithelial surfaces. Understanding the relative importance of local and systemic complement production at such locations could help to explain the differential involvement of complement in organ-specific pathology and inform the design of complement-based therapy. Here, we will describe the lessons we have learned over the last decade about the local synthesis of complement and its association with inflammatory and immunological diseases, placing emphasis on the role of local synthesis of complement in organ transplantation.
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Affiliation(s)
- Ke Li
- MRC Centre for Transplantation and Department of Nephrology and Transplantation, King's College London School of Medicine at Guy's Hospital, London, UK
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30
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Henningsson AJ, Ernerudh J, Sandholm K, Carlsson SA, Granlund H, Jansson C, Nyman D, Forsberg P, Nilsson Ekdahl K. Complement activation in Lyme neuroborreliosis — Increased levels of C1q and C3a in cerebrospinal fluid indicate complement activation in the CNS. J Neuroimmunol 2007; 183:200-7. [PMID: 17157926 DOI: 10.1016/j.jneuroim.2006.10.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 10/30/2006] [Accepted: 10/31/2006] [Indexed: 11/25/2022]
Abstract
A strong initial inflammatory response is important in neuroborreliosis. Since complement is a main player in early inflammation, we monitored the concentration and activation of complement in plasma and cerebrospinal fluid from 298 patients, of whom 23 were diagnosed with neuroborreliosis. Using sandwich ELISAs, we found significantly elevated levels of C1q, C4, C3, and C3a in cerebrospinal fluid, but not in plasma, in patients with neuroborreliosis. This finding indicates that complement plays a role in the human immune response in neuroborreliosis, that the immunologic process is compartmentalized to the CNS, and that complement activation may occur via the classical pathway.
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Affiliation(s)
- Anna J Henningsson
- Department of Infectious Diseases, Ryhov County Hospital, 551 85, Jönköping, and Division of Clinical Immunology, Department of Molecular and Clinical Medicine, Linköping University, Sweden.
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31
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Pekny M, Wilhelmsson U, Bogestål YR, Pekna M. The role of astrocytes and complement system in neural plasticity. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2007; 82:95-111. [PMID: 17678957 DOI: 10.1016/s0074-7742(07)82005-8] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In neurotrauma, brain ischemia or neurodegenerative diseases, astrocytes become reactive (which is known as reactive gliosis) and this is accompanied by an altered expression of many genes. Two cellular hallmarks of reactive gliosis are hypertrophy of astrocyte processes and the upregulation of the part of the cytoskeleton known as intermediate filaments, which are composed of nestin, vimentin, and GFAP. Our aim has been to better understand the function of reactive astrocytes in CNS diseases. Using mice deficient for astrocyte intermediate filaments (GFAP(-/-)Vim(-/-)), we were able to attenuate reactive gliosis and slow down the healing process after neurotrauma. We demonstrated the key role of reactive astrocytes in neurotrauma-at an early stage after neurotrauma, reactive astrocytes have a neuroprotective effect; at a later stage, they facilitate the formation of posttraumatic glial scars and inhibit CNS regeneration, specifically, they seem to compromise neural graft survival and integration, reduce the extent of synaptic regeneration, inhibit neurogenesis in the old age, and inhibit regeneration of severed CNS axons. We propose that reactive astrocytes are the future target for the therapeutic strategies promoting regeneration and plasticity in the brain and spinal cord in various disease conditions. Through its involvement in inflammation, opsonization, and cytolysis, complement protects against infectious agents. Although most of the complement proteins are synthesized in CNS, the role of the complement system in the normal or ischemic CNS remains unclear. Complement activiation in the CNS has been generally considered as contributing to tissue damage. However, growing body of evidence suggests that complement may be a physiological neuroprotective mechanism as well as it may participate in maintenance and repair of the adult brain.
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Affiliation(s)
- Milos Pekny
- Center for Brain Repair and Rehabilitation, Department of Clinical Neuroscience and Rehabilitation, Institute for Neuroscience and Physiology at Sahlgrenska Academy Göteborg University, 405 30 Göteborg, Sweden
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32
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Mocco J, Mack WJ, Ducruet AF, Sosunov SA, Sughrue ME, Hassid BG, Nair MN, Laufer I, Komotar RJ, Claire M, Holland H, Pinsky DJ, Connolly ES. Complement component C3 mediates inflammatory injury following focal cerebral ischemia. Circ Res 2006; 99:209-17. [PMID: 16778128 DOI: 10.1161/01.res.0000232544.90675.42] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The complement cascade has been implicated in ischemia/reperfusion injury, and recent studies have shown that complement inhibition is a promising treatment option for acute stroke. The development of clinically useful therapies has been hindered, however, by insufficient understanding of which complement subcomponents contribute to post-ischemic injury. To address this issue, we subjected mice deficient in selected complement proteins (C1q, C3, C5) to transient focal cerebral ischemia. Of the strains investigated, only C3-/- mice were protected, as demonstrated by 34% reductions in both infarct volume (P<0.01) and neurological deficit score (P<0.05). C3-deficient mice also manifested decreased granulocyte infiltration (P<0.02) and reduced oxidative stress (P<0.05). Finally, administration of a C3a-receptor antagonist resulted in commensurate neurological improvement and stroke volume reduction (P<0.05). Together, these results establish C3 activation as the key constituent in complement-related inflammatory tissue injury following stroke and suggest a C3a anaphylatoxin-mediated mechanism.
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Affiliation(s)
- J Mocco
- Department of Neurosurgery, Columbia University, 710 W 168th St, New York, NY 10032, USA
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Mack WJ, Sughrue ME, Ducruet AF, Mocco J, Sosunov SA, Hassid BG, Silverberg JZ, Ten VS, Pinsky DJ, Connolly ES. Temporal pattern of C1q deposition after transient focal cerebral ischemia. J Neurosci Res 2006; 83:883-9. [PMID: 16447284 DOI: 10.1002/jnr.20775] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Recent studies have focused on elucidating the contribution of individual complement proteins to post-ischemic cellular injury. As the timing of complement activation and deposition after cerebral ischemia is not well understood, our study investigates the temporal pattern of C1q accumulation after experimental murine stroke. Brains were harvested from mice subjected to transient focal cerebral ischemia at 3, 6, 12, and 24 hr post reperfusion. Western blotting and light microscopy were employed to determine the temporal course of C1q protein accumulation and correlate this sequence with infarct evolution observed with TTC staining. Confocal microscopy was utilized to further characterize the cellular localization and characteristics of C1q deposition. Western Blot analysis showed that C1q protein begins to accumulate in the ischemic hemisphere between 3 and 6 hr post-ischemia. Light microscopy confirmed these findings, showing concurrent C1q protein staining of neurons. Confocal microscopy demonstrated co-localization of C1q protein with neuronal cell bodies as well as necrotic cellular debris. These experiments demonstrate the accumulation of C1q protein on neurons during the period of greatest infarct evolution. This data provides information regarding the optimal time window during which a potentially neuroprotective anti-C1q strategy is most likely to achieve therapeutic success.
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Affiliation(s)
- William J Mack
- Department of Neurological Surgery, College of Physicians & Surgeons, Columbia University, New York, New York 10032, USA.
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34
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Mocco J, Sughrue ME, Ducruet AF, Komotar RJ, Sosunov SA, Connolly ES. The complement system: a potential target for stroke therapy. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 586:189-201. [PMID: 16893073 DOI: 10.1007/0-387-34134-x_13] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- J Mocco
- Department of Neurological Surgery, Columbia University, College of Physicians & Surgeons, New York, New York 10032, USA
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35
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Gavrilyuk V, Kalinin S, Hilbush BS, Middlecamp A, McGuire S, Pelligrino D, Weinberg G, Feinstein DL. Identification of complement 5a-like receptor (C5L2) from astrocytes: characterization of anti-inflammatory properties. J Neurochem 2005; 92:1140-9. [PMID: 15715664 DOI: 10.1111/j.1471-4159.2004.02942.x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Brain inflammation is regulated by endogenous substances, including neurotransmitters such as noradrenaline (NA), which can increase anti-inflammatory genes. To identify NA-regulated, anti-inflammatory genes, we used TOGA (total gene expression analysis) to screen rat astrocyte-derived RNA. NA-inducible cDNA clone DST11 encodes an isoform of the complement C5a receptor (C5aR), with 39% identity at the amino acid level to the rat C5aR, and 56% identity to a recently described human C5aR variant termed C5L2 (complement 5a-like receptor). Quantitative PCR confirmed that in astrocytes, DST11 mRNA expression is increased by NA, whereas in vivo depletion of cortical NA reduced DST11 levels. Western blot analysis demonstrated basal and NA-induced expression of DST11 as a 45 kDa protein in primary astrocytes cultures. Immunocytochemical staining of adult rat brain revealed DST11-immunoreactivity throughout brain, co-localized to neurons and astrocytes. In astrocytes, induction of nitric oxide synthase type 2 was increased by treatment with antisense oligonucleotides to DST11. Reducing DST11 expression also increased nuclear factor kappaB reporter gene, and decreased cAMP response element reporter gene activation. These results demonstrate that DST11 is a C5aR isoform expressed by glia and neurons, which is regulated by NA, and exerts anti-inflammatory functions. Changes in DST11 levels in diseased brain could therefore contribute to the progression of inflammatory damage.
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Affiliation(s)
- Vitaliy Gavrilyuk
- Department of Anesthesiology, University of Illinois, Chicago, Illinois 60612, USA.
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36
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Speth C, Dierich MP, Sopper S. HIV-infection of the central nervous system: the tightrope walk of innate immunity. Mol Immunol 2005; 42:213-28. [PMID: 15488609 DOI: 10.1016/j.molimm.2004.06.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Infection of the central nervous system (CNS) by HIV is a frequent and sometimes very early event in the course of HIV pathogenesis. Possible consequences are diverse symptoms of neurological dysfunction, but also the establishment of a lifelong latent viral reservoir in the brain. Whereas in the periphery innate and adaptive immunity are equal partners, the blood-brain barrier (BBB) with its restricted access of peripheral immune effectors shifts this balance in favour of the local innate immunity. Four main elements of cerebral innate immunity are discussed in the present article, including two cell types with immunological functions and two soluble immune systems: (1) the stimulation of microglial cells as the predominant brain-resident immune cell and the main local reservoir for the virus; (2) the reaction of astrocytes in response to viral infection; (3) the activation of the local complement system as important soluble immune cascade; and (4) the role of chemokines and cytokines which help to conduct and cross-link the interplay between the different immune elements. These components of the cerebral innate immunity do not act separately from each other but form a functional immunity network. A dual role of these components with both harmful and protective effects further enhances the complexity of the mutual interactions.
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Affiliation(s)
- Cornelia Speth
- Institute of Hygiene and Social Medicine, Medical University Innsbruck and Ludwig-Boltzmann-Institute for AIDS Research, Fritz-Pregl-Str. 3, A-6020 Innsbruck, Austria.
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37
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Bénard M, Gonzalez BJ, Schouft MT, Falluel-Morel A, Vaudry D, Chan P, Vaudry H, Fontaine M. Characterization of C3a and C5a receptors in rat cerebellar granule neurons during maturation. Neuroprotective effect of C5a against apoptotic cell death. J Biol Chem 2004; 279:43487-96. [PMID: 15292245 DOI: 10.1074/jbc.m404124200] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
There is now clear evidence that the Complement anaphylatoxin C3a and C5a receptors (C3aR and C5aR) are expressed in glial cells, notably in astrocytes and microglia. In contrast, very few data are available concerning the possible expression of these receptors in neurons. Here, we show that transient expression of C3aR and C5aR occurs in cerebellar granule neurons in vivo with a maximal density in 12-day-old rat, suggesting a role of these receptors during development of the cerebellum. Expression of C3aR and C5aR mRNAs and proteins was also observed in vitro in cultured cerebellar granule cells. Quantification of the mRNAs by real-time reverse transcription-PCR showed a peak of expression at day 2 in vitro (DIV 2); the C3aR and C5aR proteins were detected by Western blot analysis at DIV 4 and by flow cytometry and immunocytochemistry in differentiating neurons with a maximum density at DIV 4-9. Apoptosis of granule cells plays a crucial role for the harmonious development of the cerebellar cortex. We found that, in cultured granule neurons in which apoptosis was induced by serum deprivation and low potassium concentration, a C5aR agonist promoted cell survival and inhibited caspase-3 activation and DNA fragmentation. The neuroprotective effect of the C5aR agonist was associated with a marked inhibition of caspase-9 activity and partial restoration of mitochondrial integrity. Our results provide the first evidence that C3aR and C5aR are both expressed in cerebellar granule cells during development and that C5a, but not C3a, is a potent inhibitor of apoptotic cell death in cultured granule neurons.
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Affiliation(s)
- Magalie Bénard
- European Institute for Peptide Research (IFRMP 23), INSERM U519, University of Rouen, 76183, France.
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Abstract
The spectrum of inflammatory diseases is nowadays considered to include diverse diseases of the central nervous system (CNS). Current evidence suggests that syndromes such as Alzheimer's disease (AD) have important inflammatory and immune components and may be amenable to treatment by anti-inflammatory and immunotherapeutic approaches. Compelling evidence has been reported that complement activation occurs in the brain with Alzheimer's disease, and that this contributes to the development of a local inflammatory state that is correlated with cognitive dysfunction. The complement system is a critical element of the innate immune system recognizing and killing, or targeting for destruction, otherwise pathogenic organisms. In addition to triggering the generation of a membranolytic complex, complement proteins interact with cell surface receptors to promote a local inflammatory response that contributes to the protection and healing of the host. Complement activation causes inflammation and cell damage, yet it is an essential component in trying to eliminate cell debris and potentially toxic protein aggregates. It is the balance of these seemingly competing events--the "Yin" and the "Yang"--that influences the ultimate state of neuronal function. Knowledge of the unique molecular interactions that occur in the development of Alzheimer's disease, the functional consequences of those interactions, and the proportional contribution of each element to this disorder, should facilitate the design of effective therapeutic strategies for this disease.
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Affiliation(s)
- Yong Shen
- Haldeman Laboratory of Molecular and Cellular Neurobiology, Sun Health Research Institute, 10515 West Santa Fe Drive, Sun City, AZ 85351, USA.
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Hosokawa M, Klegeris A, Maguire J, McGeer PL. Expression of complement messenger RNAs and proteins by human oligodendroglial cells. Glia 2003; 42:417-23. [PMID: 12730962 DOI: 10.1002/glia.10234] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Neurons, astrocytes, microglia, and endothelial cells are capable of synthesizing most, if not all, of the complement proteins. Little is known, however, about the capacity of oligodendroglial cells to generate complement components. This study evaluated expression of complement mRNAs and their protein products by human oligodendrocytes. Cells were isolated and cultured from white matter of seven adult cases that had undergone surgical temporal lobe resection for epilepsy. Oligodendroglial cultures were characterized by the expression of such cell type-specific mRNAs as myelin proteolipid protein (PLP), oligodendrocyte-specific protein (OSP), and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and were further characterized by immunostaining for such differentiation markers as myelin basic protein (MBP), PLP, CNPase, and O4. RT-PCR analysis showed that the oligodendroglial cells expressed detectable levels of complement mRNAs for the C1q B-chain, C1r, C1s, C2, C3, C4, C5, C6, C7, C8 gamma subunit, and C9. Immunostaining was positive for C1q, C1s, C2, C3, C4, C5, C6, C7, C8, and C9. Double immunostaining for the oligodendrocyte marker O4 and the complement protein C3 demonstrated that all O4-positive cells were also positive for C3, indicating constitutive C3 expression. These results indicate that oligodendroglial cells may be a source of complement proteins in human brain and thus could contribute to the pathogenesis of several neurodegenerative and inflammatory diseases of the CNS, such as Alzheimer's disease, multiple sclerosis, and progressive supranuclear palsy, where complement-activated oligodendrocytes are abundant.
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Affiliation(s)
- Masato Hosokawa
- Kinsmen Laboratory of Neurological Research, University of British Columbia, Vancouver, British Columbia, Canada
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40
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Vinci G, Lynch NJ, Duponchel C, Lebastard TM, Milon G, Stover C, Schwaeble W, Tosi M. In vivo biosynthesis of endogenous and of human C1 inhibitor in transgenic mice: tissue distribution and colocalization of their expression. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:5948-54. [PMID: 12421980 DOI: 10.4049/jimmunol.169.10.5948] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We have produced transgenic mice expressing human C1 inhibitor mRNA and protein under the control of the human promoter and regulatory elements. The transgene was generated using a minigene construct in which most of the human C1 inhibitor gene (C1NH) was replaced by C1 inhibitor cDNA. The construct retained the promoter region extending 1.18 kb upstream of the transcription start site, introns 1 and 2 as well as a stretch of 2.5 kb downstream of the polyadenylation site, and therefore carried all known elements involved in transcriptional regulation of the C1NH gene. Mice with high serum levels of human C1 inhibitor, resulting from multiple tandem integrations of the C1 inhibitor transgene, were selected. Immunohistochemistry in combination with in situ hybridization was applied to localize the sites of C1 inhibitor biosynthesis and to demonstrate its local production in brain, spleen, liver, heart, kidney, and lung. The distribution of human C1 inhibitor-expressing cells was qualitatively indistinguishable from that of its mouse counterpart, but expression levels of the transgene were significantly higher. In the spleen, production of C1 inhibitor was colocalized with that of a specific marker for white pulp follicular dendritic cells. This study demonstrates a stringently regulated expression of both the endogenous and the transgenic human C1 inhibitor gene and reveals local biosynthesis of C1 inhibitor at multiple sites in which the components of the macromolecular C1 complex are also produced.
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Affiliation(s)
- Giovanna Vinci
- Institut National de la Santé et de la Recherche Médicale E0021, Département d'Immunologie, Institut Pasteur, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France.
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41
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Nakagawa M, Nakashima S, Banno Y, Yamada J, Sawada M, Yoshimura SI, Kaku Y, Iwama T, Shinoda J, Sakai N. Increased expression and secretion of r-Gsp protein, rat counterpart of complement C1s precursor, during cyclic AMP-induced differentiation in rat C6 glioma cells. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 106:12-21. [PMID: 12393260 DOI: 10.1016/s0169-328x(02)00404-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The gene, termed r-gsp, was originally isolated during identification of differentiation-associated molecules in rat C6 glial cells. Its mRNA expression was markedly increased during cAMP-induced glial cell differentiation. The deduced amino acid sequence of r-gsp was homologous to those of complement C1s precursors of hamsters and humans. In the present study, we raised anti-peptide antibody against r-Gsp protein and analyzed its change during cAMP-induced differentiation. The 90-kDa r-Gsp protein increased time-dependently and reached the maximal level ( approximately 7.6-fold increase) at 24 h in response to dibutyryl cyclic AMP (dbcAMP) and theophylline. Moreover, it was secreted into the medium and then was cleaved to form disulfide-linked fragments, one of which was 30 kDa, similar to C1s, suggesting its processing in the extracellular space. In fact, the partially purified r-Gsp from culture medium was cleaved by active human C1r to form a 30-kDa polypeptide. Moreover, secreted r-Gsp protein cleaved human C4alpha to yield C4alpha' and associated with human serum C1-esterase inhibitor, strongly suggesting that r-Gsp protein is rat C1s. However, in C6 cells overexpressing r-Gsp, their morphology and proliferation rate were similar to those in parent C6 cells. These results suggest that r-Gsp protein could not induce glial differentiation alone, and suggest that r-Gsp protein was secreted as a proenzyme and processed in culture medium. Its possible role in glial cell differentiation will be discussed.
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Affiliation(s)
- Masanori Nakagawa
- Department of Neurosurgery, Gifu University School of Medicine, Tsukasamachi-40, Japan
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42
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Bellander BM, Singhrao SK, Ohlsson M, Mattsson P, Svensson M. Complement activation in the human brain after traumatic head injury. J Neurotrauma 2001; 18:1295-311. [PMID: 11780861 DOI: 10.1089/08977150152725605] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The complement cascade has been suggested to be involved in the development of secondary brain injuries following brain contusions, based on animal experiments. The aim of the present study was to examine the possible involvement of the complement cascade following traumatic head injury in the human brain. Sixteen patients were included in this study, 12-77 years of age, treated at the neurointensive care unit for traumatic brain contusions. All of these patients were operated with frontal or temporal lobe resection due to intractable intracranial hypertension. The resected tissue was analyzed with regard to components related to complement activation. The time interval between accident and operation was 2-82 h. Brain tissue from three patients operated with hippocampectomy due to epilepsy, including temporal lobe resection, were used as controls. We found increased immunoreactivity for complement components C1q, C3b, and C3d and the membrane attack complex (MAC), C5b-9, in the immediate vicinity of neurons in the penumbra area of the contusion. These findings constitute histological evidence for activation of the complement cascade in the penumbra of cortical contusions in the human brain. Using in situ hybridization, we also found C3-mRNA in the penumbra, suggesting a local synthesis of complement. Furthermore, upregulation of the endogenous complement regulator clusterin was found in some neurons in the same area. We suggest that unknown compounds in the debris from injured neurons or myelin breakdown products trigger complement activation, including formation of C5b-9. Activated complement components may stimulate accumulation of inflammatory cells and formation of brain edema, as well as having membrane destructive effects by the end product MAC, thereby being mediators in the development of secondary brain damage.
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Affiliation(s)
- B M Bellander
- Department of Clinical Neuroscience, Section for Neurosurgery, Karolinska Hospital, Stockholm, Sweden.
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43
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Chang JW, Young DA, Coleman PD, O'Banion MK. Two-dimensional gel analysis of secreted proteins induced by interleukin-1 beta in rat astrocytes. Neurochem Int 2001; 39:349-59. [PMID: 11578770 DOI: 10.1016/s0197-0186(01)00042-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Interleukin-1 beta (IL-1 beta) is a pro-inflammatory cytokine produced in the brain by endogenous microglial cells responding to injury. Levels of IL-1 beta are elevated in several neurodegenerative disorders, including Alzheimer's disease. IL-1 beta, which can act as a mitogen for astrocytes, also elicits the expression and secretion of multiple factors and paracrine 'second messengers' such as other cytokines, nerve growth factor, prostaglandins and nitric oxide that may in turn modulate neuronal and glial responses to injury. Utilizing giant, high-resolution two-dimensional gel electrophoresis, we have sought to more fully define the potential range of protein mediators that are secreted by astrocytes treated with IL-1 beta. In cultured rat astrocytes, we observe dramatic increases in the secretion of eight different protein species after 24 h of treatment with human recombinant IL-1 beta (1 U/ml). Seven of the proteins are also induced by tumor necrosis factor-alpha or basic fibroblast growth factor. Based on immunoprecipitation with specific antisera, we have identified three of these proteins as plasminogen activator inhibitor type-1, ceruloplasmin, and complement component C3. The identities of the other proteins, including the IL-1 beta-specific induction, are currently unknown. Characterization of these downstream modulators of IL-1 beta action complements gene-based approaches and will provide a better understanding of astrocyte responses to injury as well as markers for astrocyte activation in neurodegenerative diseases.
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Affiliation(s)
- J W Chang
- Department of Neurobiology and Anatomy, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Box 603, 14642, Rochester, NY, USA
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44
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Byun SJ, Bahk YY, Ryoo ZY, Kim KE, Hwang HY, Lee JW, Yi JY, Kim TY. Identification of cDNA encoding a serine protease homologous to human complement C1r precursor from grafted mouse skin. J Invest Dermatol 2001; 116:374-9. [PMID: 11231310 DOI: 10.1046/j.1523-1747.2001.01257.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We isolated a cDNA clone from grafted mouse skin that encodes a serine protease homologous to human C1r. The C1r protease is involved in the activation of the first component of the classical pathway in the complement system. In order to identify novel transcripts whose expression is regulated in grafted mouse skin, we first performed differential display reverse transcription polymerase chain reaction analysis and obtained 18 partial cDNA clones whose protein products are likely to play an important role in allograft rejection. One of these showed significant sequence homology with human complement C1r precursor. The other clones displayed no homology to any known sequences, however. Northern blot analysis demonstrated that the level of this transcript was upregulated in day 8 postgrafted skin. The full-length cDNA 2121 nucleotides in length obtained from screening a mouse skin cDNA library contained a single open reading frame encoding 707 amino acid residues with a calculated molecular weight of 80,732 Da. Its deduced amino acid sequence revealed an 81% identity and 89% similarity to the human C1r counterpart. In particular, mouse C1r contained His501, Asp559, and Ser656, which were conserved among this group of serine proteases. This protein was thus designated as mouse C1r. We have expressed a truncated fragment of C1r protein without the N-terminal hydrophobic sequence in Escherichia coli and generated a polyclonal antibody against it. Subsequent immunohistochemical analysis confirmed that mouse C1r was significantly expressed 8 d after the skin graft in both allografted and autografted skins, compared with normal skins. These collective data suggest that a component of the complement system, C1r, might contribute to the graft versus host immune responses in mice.
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Affiliation(s)
- S J Byun
- Department of Dermatology-Immunology, Kangnam St. Mary Hospital, College of Medicine, Seoul, Korea
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45
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Singhrao SK, Neal JW, Rushmere NK, Morgan BP, Gasque P. Spontaneous classical pathway activation and deficiency of membrane regulators render human neurons susceptible to complement lysis. THE AMERICAN JOURNAL OF PATHOLOGY 2000; 157:905-18. [PMID: 10980130 PMCID: PMC1885712 DOI: 10.1016/s0002-9440(10)64604-4] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This study investigated the capacity of neurons and astrocytes to spontaneously activate the complement system and control activation by expressing complement regulators. Human fetal neurons spontaneously activated complement through the classical pathway in normal and immunoglobulin-deficient serum and C1q binding was noted on neurons but not on astrocytes. A strong staining for C4, C3b, iC3b neoepitope and C9 neoepitope was also found on neurons. More than 40% of human fetal neurons were lysed when exposed to normal human serum in the presence of a CD59-blocking antibody, whereas astrocytes were unaffected. Significant reduction in neuronal cell lysis was observed after the addition of soluble complement receptor 1 at 10 microg/ml. Fetal neurons were stained for CD59 and CD46 and were negative for CD55 and CD35. In contrast, fetal astrocytes were strongly stained for CD59, CD46, CD55, and were negative for CD35. This study demonstrates that human fetal neurons activate spontaneously the classical pathway of complement in an antibody-independent manner to assemble the cytolytic membrane attack complex on their membranes, whereas astrocytes are unaffected. One reason for the susceptibility of neurons to complement-mediated damage in vivo may reside in their poor capacity to control complement activation.
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MESH Headings
- Antibodies, Blocking/pharmacology
- Antigens, CD/genetics
- Antigens, CD/metabolism
- Astrocytes/cytology
- Astrocytes/drug effects
- Astrocytes/physiology
- Brain/cytology
- Brain/embryology
- Cells, Cultured
- Complement Activation/physiology
- Complement C3-C5 Convertases/physiology
- Complement Inactivator Proteins/deficiency
- Complement Inactivator Proteins/genetics
- Complement Inactivator Proteins/metabolism
- Complement Pathway, Classical/physiology
- Fetus
- Fluorescent Antibody Technique, Indirect
- Humans
- Image Processing, Computer-Assisted
- In Situ Hybridization
- Membrane Cofactor Protein
- Membrane Glycoproteins/deficiency
- Membrane Glycoproteins/genetics
- Membrane Glycoproteins/metabolism
- Neurons/cytology
- Neurons/drug effects
- Neurons/physiology
- RNA/analysis
- RNA, Messenger/metabolism
- Receptors, Complement/deficiency
- Receptors, Complement/genetics
- Receptors, Complement/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
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Affiliation(s)
- S K Singhrao
- Department of Medical Biochemistry, Brain Inflammation and Immunity Group, University of Wales College of Medicine, Heath Park, Cardiff, United Kingdom.
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46
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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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47
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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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48
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Van Beek J, Chan P, Bernaudin M, Petit E, MacKenzie ET, Fontaine M. Glial responses, clusterin, and complement in permanent focal cerebral ischemia in the mouse. Glia 2000; 31:39-50. [PMID: 10816605 DOI: 10.1002/(sici)1098-1136(200007)31:1<39::aid-glia40>3.0.co;2-1] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
There is considerable evidence that complement activation occurs within the CNS in inflammatory and degenerative disorders, but little is known about its involvement in the pathophysiology of cerebral ischemia. Our study sought to characterize the glial response and the expression of complement factors after permanent focal cerebral ischemia in the mouse, using semiquantitative reverse transcription-polymerase chain reaction (RT-PCR), in situ hybridization, and immunohistochemistry. mRNA expression of glial fibrillary acidic protein (GFAP) increased at day 1 and peaked 3 days after middle cerebral artery (MCA) occlusion in the perifocal area. Immunohistochemical staining for GFAP indicated that astroglia were activated the day after MCA occlusion. Microglial activation, as assessed by lectin-binding experiments, increased by 1 day after MCA occlusion in the perifocal area and peaked at 3 days postocclusion. RT-PCR experiments demonstrated an increased expression of clusterin, C1qB, and C4 mRNA in the ischemic cortex, with a peak level at 3 days after MCA occlusion. Clusterin, C1qB, and C4 mRNA were located in the perifocal area, as assessed by in situ hybridization. Reactive astrocytes within the cortex medial to the ischemic lesion were found to be strongly immunoreactive for clusterin. In addition, we observed C1q-positive macrophage-like cells within the infarcted core at 3 days postocclusion. At 7 days after the onset of ischemia, increased C4 immunostaining was restricted to perifocal neurons. We conclude that local expression of complement components may contribute to the inflammation observed in this model, thereby representing an important process in secondary injury mechanisms after focal cerebral ischemia.
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Affiliation(s)
- J Van Beek
- European Institute for Peptide Research (IFRM P23), INSERM U519, Faculté Mixte de Médecine et de Pharmacie, Rouen Cedex, France.
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49
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Sloane JA, Hollander W, Rosene DL, Moss MB, Kemper T, Abraham CR. Astrocytic hypertrophy and altered GFAP degradation with age in subcortical white matter of the rhesus monkey. Brain Res 2000; 862:1-10. [PMID: 10799662 DOI: 10.1016/s0006-8993(00)02059-x] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reactive astrocytosis is a well known phenomenon that occurs in the normal aging process of the brain. While many studies indicate astrocytic hypertrophy and glial fibrillary acidic protein (GFAP) content increase with age in the hippocampal formation of certain animal models, it is unclear whether these findings are generalizable to the primate and to other areas of the brain. In this study, we quantitatively assessed age-related changes in astrocytic cell size and density in a rhesus monkey model of normal aging. By GFAP immunohistochemistry, we observed an increase in GFAP(+) cell size but not density in all subcortical white matter areas of the frontal, temporal, and parietal cortices. No significant increases in astrocyte hypertrophy were observed in any gray matter area examined. In addition, Western blotting experiments showed increases in total and degraded GFAP content with age, suggesting altered degradation and possibly production of GFAP occur with age.
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Affiliation(s)
- J A Sloane
- Department of Pathology, Boston University School of Medicine, 715 Albany, Boston, MA, USA
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50
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Veerhuis R, Janssen I, De Groot CJ, Van Muiswinkel FL, Hack CE, Eikelenboom P. Cytokines associated with amyloid plaques in Alzheimer's disease brain stimulate human glial and neuronal cell cultures to secrete early complement proteins, but not C1-inhibitor. Exp Neurol 1999; 160:289-99. [PMID: 10630213 DOI: 10.1006/exnr.1999.7199] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Complement activation products C1q, C4c/d, and C3c/d in amyloid plaques in Alzheimer's disease probably result from direct binding and activation of C1 by amyloid beta peptides. RT-PCR and in situ hybridization studies have shown that several complement factors are produced in the brain parenchyma. In the present study, cytokines that can be detected in amyloid plaques (i.e., interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-alpha) were found to differentially stimulate the expression of C1 subcomponents, C1-Inhibitor (C1-Inh), C4, and C3, by astrocyte and microglial cell cultures derived from postmortem adult, human brain specimens and by neuroblastoma cell lines in culture. C1r and C1s were secreted at low levels by astrocytes and neuroblastoma cell lines. Exposure of cells to IL-1 alpha, IL-1 beta, TNF-alpha and to a far lesser extent IL-6, markedly upregulated C1r, C1s, and C3 production. C4 synthesis increased in response to interferon (IFN)-gamma and IL-6, whereas that of C1-Inh could be stimulated only by IFN-gamma. Thus, C1-Inh production is refractory to stimulation by plaque-associated cytokines, whereas these cytokines do stimulate C1r, C1s, and also C4 and C3 secretion by astrocytes and neuronal cells in culture. In contrast to the amyloid plaque associated cytokines IL-1 beta, IL-1 alpha, and TNF-alpha, the amyloid peptide A beta 1-42 itself did not stimulate C1r and C1s synthesis by astrocytes, microglial cells, or neuroblastoma cell lines. Microglial cells were the only cell type that constitutively expressed C1q. The ability of C1q to reassociate with newly formed C1r and C1s upon activation of C1 and subsequent inactivation by C1-Inh, may enable ongoing complement activation at sites of amyloid deposition, especially when C1-Inh is consumed and not replaced.
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Affiliation(s)
- R Veerhuis
- Department of Psychiatry, Graduate School Neurosciences, Vrije Universiteit, Amsterdam, The Netherlands
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