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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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2
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Guo Y, Endmayr V, Zekeridou A, McKeon A, Leypoldt F, Hess K, Kalinowska-Lyszczarz A, Klang A, Pakozdy A, Höftberger E, Hametner S, Haider C, De Simoni D, Peters S, Gelpi E, Röcken C, Oberndorfer S, Lassmann H, Lucchinetti CF, Höftberger R. New insights into neuropathology and pathogenesis of autoimmune glial fibrillary acidic protein meningoencephalomyelitis. Acta Neuropathol 2024; 147:31. [PMID: 38310187 PMCID: PMC10838242 DOI: 10.1007/s00401-023-02678-7] [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: 09/05/2023] [Revised: 12/06/2023] [Accepted: 12/24/2023] [Indexed: 02/05/2024]
Abstract
Anti-glial fibrillary acidic protein (GFAP) meningoencephalomyelitis (autoimmune GFAP astrocytopathy) is a new autoimmune central nervous system (CNS) disease diagnosable by the presence of anti-GFAP autoantibodies in the cerebrospinal fluid and presents as meningoencephalomyelitis in the majority of patients. Only few neuropathological reports are available and little is known about the pathogenic mechanisms. We performed a histopathological study of two autopsies and nine CNS biopsies of patients with anti-GFAP autoantibodies and found predominantly a lymphocytic and in one autopsy case a granulomatous inflammatory phenotype. Inflammatory infiltrates were composed of B and T cells, including tissue-resident memory T cells. Although obvious astrocytic damage was absent in the GFAP-staining, we found cytotoxic T cell-mediated reactions reflected by the presence of CD8+/perforin+/granzyme A/B+ cells, polarized towards astrocytes. MHC-class-I was upregulated in reactive astrocytes of all biopsies and two autopsies but not in healthy controls. Importantly, we observed a prominent immunoreactivity of astrocytes with the complement factor C4d. Finally, we provided insight into an early phase of GFAP autoimmunity in an autopsy of a pug dog encephalitis that was characterized by marked meningoencephalitis with selective astrocytic damage with loss of GFAP and AQP4 in the lesions.Our histopathological findings indicate that a cytotoxic T cell-mediated immune reaction is present in GFAP autoimmunity. Complement C4d deposition on astrocytes could either represent the cause or consequence of astrocytic reactivity. Selective astrocytic damage is prominent in the early phase of GFAP autoimmunity in a canine autopsy case, but mild or absent in subacute and chronic stages in human disease, probably due to the high regeneration potential of astrocytes. The lymphocytic and granulomatous phenotypes might reflect different stages of lesion development or patient-specific modifications of the immune response. Future studies will be necessary to investigate possible implications of pathological subtypes for clinical disease course and therapeutic strategies.
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Affiliation(s)
- Yong Guo
- Department of Neurology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Verena Endmayr
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Anastasia Zekeridou
- Department of Neurology, Mayo Clinic, Rochester, MN, 55905, USA
- Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Andrew McKeon
- Department of Neurology, Mayo Clinic, Rochester, MN, 55905, USA
- Laboratory Medicine and Pathology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | - Frank Leypoldt
- Institute of Clinical Chemistry, University Medical Center Schleswig-Holstein Kiel, Lübeck, Germany
- Department of Neurology, University Medical Center Schleswig-Holstein and Kiel University, Kiel, Germany
| | - Katharina Hess
- Institute of Neuropathology, University Hospital Muenster, Muenster, North Rhine Westphalia, Germany
- Department of Pathology, University Medical Center Schleswig-Holstein, Kiel, Germany
| | - Alicja Kalinowska-Lyszczarz
- Department of Neurology, Division of Neurochemistry and Neuropathology, Poznan University of Medical Sciences, Poznań, Poland
| | - Andrea Klang
- Institute of Pathology, University of Veterinary Medicine, Vienna, Austria
| | - Akos Pakozdy
- Internal Medicine, University Clinic for Small Animals, University of Veterinary Medicine, Vienna, Austria
| | - Elisabeth Höftberger
- Internal Medicine, University Clinic for Small Animals, University of Veterinary Medicine, Vienna, Austria
| | - Simon Hametner
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Carmen Haider
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Désirée De Simoni
- Division of Neurology, Karl Landsteiner University of Health Sciences, University Hospital, St. Pölten, Austria
| | - Sönke Peters
- Clinic for Radiology and Neuroradiology, University Hospital Schleswig-Holstein Campus Kiel, Kiel, Germany
| | - Ellen Gelpi
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria
| | - Christoph Röcken
- Department of Pathology, University Medical Center Schleswig-Holstein, Kiel, Germany
| | - Stefan Oberndorfer
- Division of Neurology, Karl Landsteiner University of Health Sciences, University Hospital, St. Pölten, Austria
| | - Hans Lassmann
- Center for Brain Research, Medical University of Vienna, Vienna, Austria
| | | | - Romana Höftberger
- Division of Neuropathology and Neurochemistry, Department of Neurology, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
- Comprehensive Center for Clinical Neurosciences and Mental Health, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria.
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Marin WM, Augusto DG, Wade KJ, Hollenbach JA. High-throughput complement component 4 genomic sequence analysis with C4Investigator. HLA 2024; 103:e15273. [PMID: 37899688 PMCID: PMC11099535 DOI: 10.1111/tan.15273] [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: 05/30/2023] [Revised: 09/01/2023] [Accepted: 10/13/2023] [Indexed: 10/31/2023]
Abstract
The complement component 4 gene loci, composed of the C4A and C4B genes and located on chromosome 6, encodes for complement component 4 (C4) proteins, a key intermediate in the classical and lectin pathways of the complement system. The complement system is an important modulator of immune system activity and is also involved in the clearance of immune complexes and cellular debris. C4A and C4B gene loci exhibit copy number variation, with each composite gene varying between 0 and 5 copies per haplotype. C4A and C4B genes also vary in size depending on the presence of the human endogenous retrovirus (HERV) in intron 9, denoted by C4(L) for long-form and C4(S) for short-form, which affects expression and is found in both C4A and C4B. Additionally, human blood group antigens Rodgers and Chido are located on the C4 protein, with the Rodger epitope generally found on C4A protein, and the Chido epitope generally found on C4B protein. C4A and C4B copy number variation has been implicated in numerous autoimmune and pathogenic diseases. Despite the central role of C4 in immune function and regulation, high-throughput genomic sequence analysis of C4A and C4B variants has been impeded by the high degree of sequence similarity and complex genetic variation exhibited by these genes. To investigate C4 variation using genomic sequencing data, we have developed a novel bioinformatic pipeline for comprehensive, high-throughput characterization of human C4A and C4B sequences from short-read sequencing data, named C4Investigator. Using paired-end targeted or whole genome sequence data as input, C4Investigator determines the overall gene copy numbers, as well as C4A, C4B, C4(Rodger), C4(Ch), C4(L), and C4(S). Additionally, C4Ivestigator reports the full overall C4A and C4B aligned sequence, enabling nucleotide level analysis. To demonstrate the utility of this workflow we have analyzed C4A and C4B variation in the 1000 Genomes Project Data set, showing that these genes are highly poly-allelic with many variants that have the potential to impact C4 protein function.
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Affiliation(s)
- Wesley M. Marin
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, San Francisco, CA, United States
| | - Danillo G. Augusto
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, San Francisco, CA, United States
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, United States
- Programa de Pós-Graduação em Genética, Universidade Federal do Paraná, Curitiba, Brazil
| | - Kristen J. Wade
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, San Francisco, CA, United States
| | - Jill A. Hollenbach
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, San Francisco, CA, United States
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, United States
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4
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Marin WM, Augusto DG, Wade KJ, Hollenbach JA. High-throughput complement component 4 genomic sequence analysis with C4Investigator. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.18.549551. [PMID: 37503256 PMCID: PMC10370142 DOI: 10.1101/2023.07.18.549551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
The complement component 4 gene locus, composed of the C4A and C4B genes and located on chromosome 6, encodes for C4 protein, a key intermediate in the classical and lectin pathways of the complement system. The complement system is an important modulator of immune system activity and is also involved in the clearance of immune complexes and cellular debris. The C4 gene locus exhibits copy number variation, with each composite gene varying between 0-5 copies per haplotype, C4 genes also vary in size depending on the presence of the HERV retrovirus in intron 9, denoted by C4(L) for long-form and C4(S) for short-form, which modulates expression and is found in both C4A and C4B. Additionally, human blood group antigens Rodgers and Chido are located on the C4 protein, with the Rodger epitope generally found on C4A protein, and the Chido epitope generally found on C4B protein. C4 copy number variation has been implicated in numerous autoimmune and pathogenic diseases. Despite the central role of C4 in immune function and regulation, high-throughput genomic sequence analysis of C4 variants has been impeded by the high degree of sequence similarity and complex genetic variation exhibited by these genes. To investigate C4 variation using genomic sequencing data, we have developed a novel bioinformatic pipeline for comprehensive, high-throughput characterization of human C4 sequence from short-read sequencing data, named C4Investigator. Using paired-end targeted or whole genome sequence data as input, C4Investigator determines gene copy number for overall C4, C4A, C4B, C4(Rodger), C4(Ch), C4(L), and C4(S), additionally, C4Ivestigator reports the full overall C4 aligned sequence, enabling nucleotide level analysis of C4. To demonstrate the utility of this workflow we have analyzed C4 variation in the 1000 Genomes Project Dataset, showing that the C4 genes are highly poly-allelic with many variants that have the potential to impact C4 protein function.
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Affiliation(s)
- Wesley M. Marin
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, San Francisco, CA, United States
| | - Danillo G. Augusto
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, San Francisco, CA, United States
- Department of Biological Sciences, University of North Carolina Charlotte, Charlotte, NC, United States
- Programa de Pós-Graduação em Genética, Universidade Federal do Paraná, Curitiba, Brazil
| | - Kristen J. Wade
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, San Francisco, CA, United States
| | - Jill A. Hollenbach
- Weill Institute for Neurosciences, Department of Neurology, University of California San Francisco, San Francisco, CA, United States
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, United States
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5
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Rapino F, Natoli T, Limone F, O'Connor E, Blank J, Tegtmeyer M, Chen W, Norabuena E, Narula J, Hazelbaker D, Angelini G, Barrett L, O'Neil A, Beattie UK, Thanos JM, de Rivera H, Sheridan SD, Perlis RH, McCarroll SA, Stevens B, Subramanian A, Nehme R, Rubin LL. Small-molecule screen reveals pathways that regulate C4 secretion in stem cell-derived astrocytes. Stem Cell Reports 2023; 18:237-253. [PMID: 36563689 PMCID: PMC9860128 DOI: 10.1016/j.stemcr.2022.11.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 11/17/2022] [Accepted: 11/19/2022] [Indexed: 12/24/2022] Open
Abstract
In the brain, the complement system plays a crucial role in the immune response and in synaptic elimination during normal development and disease. Here, we sought to identify pathways that modulate the production of complement component 4 (C4), recently associated with an increased risk of schizophrenia. To design a disease-relevant assay, we first developed a rapid and robust 3D protocol capable of producing large numbers of astrocytes from pluripotent cells. Transcriptional profiling of these astrocytes confirmed the homogeneity of this population of dorsal fetal-like astrocytes. Using a novel ELISA-based small-molecule screen, we identified epigenetic regulators, as well as inhibitors of intracellular signaling pathways, able to modulate C4 secretion from astrocytes. We then built a connectivity map to predict and validate additional key regulatory pathways, including one involving c-Jun-kinase. This work provides a foundation for developing therapies for CNS diseases involving the complement cascade.
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Affiliation(s)
- Francesca Rapino
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
| | - Ted Natoli
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Francesco Limone
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Leiden University Medical Center, LUMC, 2333 ZA Leiden, the Netherlands
| | - Erin O'Connor
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Jack Blank
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Matthew Tegtmeyer
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - William Chen
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Erika Norabuena
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Juhi Narula
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Dane Hazelbaker
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Gabriella Angelini
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Lindy Barrett
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Alison O'Neil
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Ursula K Beattie
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
| | - Jessica M Thanos
- Center for Quantitative Health, Center for Genomic Medicine and Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Heather de Rivera
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Steven D Sheridan
- Center for Quantitative Health, Center for Genomic Medicine and Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Roy H Perlis
- Center for Quantitative Health, Center for Genomic Medicine and Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA; Department of Psychiatry, Harvard Medical School, Boston, MA, USA
| | - Steven A McCarroll
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Beth Stevens
- Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Ralda Nehme
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Lee L Rubin
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA 02138, USA; Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA; Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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6
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Cable DM, Murray E, Shanmugam V, Zhang S, Zou LS, Diao M, Chen H, Macosko EZ, Irizarry RA, Chen F. Cell type-specific inference of differential expression in spatial transcriptomics. Nat Methods 2022; 19:1076-1087. [PMID: 36050488 PMCID: PMC10463137 DOI: 10.1038/s41592-022-01575-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Accepted: 07/15/2022] [Indexed: 12/13/2022]
Abstract
A central problem in spatial transcriptomics is detecting differentially expressed (DE) genes within cell types across tissue context. Challenges to learning DE include changing cell type composition across space and measurement pixels detecting transcripts from multiple cell types. Here, we introduce a statistical method, cell type-specific inference of differential expression (C-SIDE), that identifies cell type-specific DE in spatial transcriptomics, accounting for localization of other cell types. We model gene expression as an additive mixture across cell types of log-linear cell type-specific expression functions. C-SIDE's framework applies to many contexts: DE due to pathology, anatomical regions, cell-to-cell interactions and cellular microenvironment. Furthermore, C-SIDE enables statistical inference across multiple/replicates. Simulations and validation experiments on Slide-seq, MERFISH and Visium datasets demonstrate that C-SIDE accurately identifies DE with valid uncertainty quantification. Last, we apply C-SIDE to identify plaque-dependent immune activity in Alzheimer's disease and cellular interactions between tumor and immune cells. We distribute C-SIDE within the R package https://github.com/dmcable/spacexr .
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Affiliation(s)
- Dylan M Cable
- Department of Electrical Engineering and Computer Science, MIT, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Data Sciences, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Evan Murray
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Vignesh Shanmugam
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA
| | - Simon Zhang
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Luli S Zou
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Data Sciences, Dana-Farber Cancer Institute, Boston, MA, USA
- Department of Biostatistics, Harvard University, Boston, MA, USA
| | - Michael Diao
- Department of Electrical Engineering and Computer Science, MIT, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Haiqi Chen
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Cecil H. and Ida Green Center for Reproductive Biology Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Evan Z Macosko
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA, USA
| | - Rafael A Irizarry
- Department of Data Sciences, Dana-Farber Cancer Institute, Boston, MA, USA.
- Department of Biostatistics, Harvard University, Boston, MA, USA.
| | - Fei Chen
- Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, USA.
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7
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Association of complement component 4 with neuroimmune abnormalities in the subventricular zone in schizophrenia and autism spectrum disorders. Neurobiol Dis 2022; 173:105840. [PMID: 35995342 PMCID: PMC9582995 DOI: 10.1016/j.nbd.2022.105840] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 08/12/2022] [Accepted: 08/14/2022] [Indexed: 02/06/2023] Open
Abstract
An early inflammatory insult is the most recognized risk factor associated with neurodevelopmental psychiatric disorders, even more so than genetic variants. Notably, complement component 4 (C4), a molecule involved in inflammatory responses, has been strongly associated with schizophrenia (SZ) and its role in other neurodevelopmental disorders, such as autism (ASD), is an area of active investigation. However, while C4 in SZ has been implicated in the context of synaptic pruning, little is known about its neuroinflammatory role. The subventricular zone (SVZ) is a region heavily involved in neurodevelopment and neuroimmune interactions through the lifespan; thus, it is a region wherein C4 may play a vital role in disease pathology. Using in situ hybridization with radioactive riboprobes and RNAscope, we identified robust astrocytic expression of C4 in the SVZ and in the septum pellucidum. C4 was also expressed in ependyma, neurons, and Ki67+ progenitor cells. Examination of mRNA levels showed elevated C4 in both ASD and SZ, with higher expression in SZ compared to controls. Targeted transcriptomic analysis of inflammatory pathways revealed a strong association of complement system genes with SZ, and to a lesser extent, ASD, as well as generalized immune dysregulation without a strong association with known infectious pathways. Analysis of differentially expressed genes (DEGs) showed that ASD DEGs were enriched in adaptive immune system functions such as Th cell differentiation, while SZ DEGs were enriched in innate immune system functions, including NF-κB and toll like receptor signaling. Moreover, the number of Ki67+ cells was significantly higher in ASD compared to SZ and controls. Taken together, these results support a role for C4 into inflammatory-neuroimmune dysregulation observed in SZ and ASD pathology.
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8
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The Role of Complement C3a Receptor in Stroke. Neuromolecular Med 2019; 21:467-473. [PMID: 31102134 DOI: 10.1007/s12017-019-08545-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 05/12/2019] [Indexed: 12/20/2022]
Abstract
The complement system is a key regulator of the innate immune response against diseased tissue that functions across multiple organ systems. Dysregulation of complement contributes to the pathogenesis of a number of neurological diseases including stroke. The C3a anaphylatoxin, via its cognate C3a receptor (C3aR), mediates inflammation by promoting breakdown of the blood-brain barrier and the massive infiltration of leukocytes into ischemic brain in experimental stroke models. Studies utilizing complement deficient mice as well as pharmacologic C3aR antagonists have shown a reduction in tissue injury and mortality in murine stroke models. The development of tissue-specific C3aR knockout mice and more specific C3aR antagonists is warranted to facilitate our understanding of the role of the C3aR in brain ischemia with the ultimate goal of clinical translation of therapies targeting C3aR in stroke patients.
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9
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Astrocyte-Microglia Cross Talk through Complement Activation Modulates Amyloid Pathology in Mouse Models of Alzheimer's Disease. J Neurosci 2016; 36:577-89. [PMID: 26758846 DOI: 10.1523/jneurosci.2117-15.2016] [Citation(s) in RCA: 349] [Impact Index Per Article: 43.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
UNLABELLED Increasing evidence supports a role of neuroinflammation in the pathogenesis of Alzheimer's disease (AD). Previously, we identified a neuron-glia signaling pathway whereby Aβ acts as an upstream activator of astroglial nuclear factor kappa B (NF-κB), leading to the release of complement C3, which acts on the neuronal C3a receptor (C3aR) to influence dendritic morphology and cognitive function. Here we report that astrocytic complement activation also regulates Aβ dynamics in vitro and amyloid pathology in AD mouse models through microglial C3aR. We show that in primary microglial cultures, acute C3 or C3a activation promotes, whereas chronic C3/C3a treatment attenuates, microglial phagocytosis and that the effect of chronic C3 exposure can be blocked by cotreatment with a C3aR antagonist and by genetic deletion of C3aR. We further demonstrate that Aβ pathology and neuroinflammation in amyloid precursor protein (APP) transgenic mice are worsened by astroglial NF-κB hyperactivation and resulting C3 elevation, whereas treatment with the C3aR antagonist (C3aRA) ameliorates plaque load and microgliosis. Our studies define a complement-dependent intercellular cross talk in which neuronal overproduction of Aβ activates astroglial NF-κB to elicit extracellular release of C3. This promotes a pathogenic cycle by which C3 in turn interacts with neuronal and microglial C3aR to alter cognitive function and impair Aβ phagocytosis. This feedforward loop can be effectively blocked by C3aR inhibition, supporting the therapeutic potential of C3aR antagonists under chronic neuroinflammation conditions. SIGNIFICANCE STATEMENT The complement pathway is activated in Alzheimer's disease. Here we show that the central complement factor C3 secreted from astrocytes interacts with microglial C3a receptor (C3aR) to mediate β-amyloid pathology and neuroinflammation in AD mouse models. Our study provides support for targeting C3aR as a potential therapy for Alzheimer's disease.
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Switching from astrocytic neuroprotection to neurodegeneration by cytokine stimulation. Arch Toxicol 2016; 91:231-246. [PMID: 27052459 DOI: 10.1007/s00204-016-1702-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 03/21/2016] [Indexed: 12/12/2022]
Abstract
Astrocytes, the largest cell population in the human brain, are powerful inflammatory effectors. Several studies have examined the interaction of activated astrocytes with neurons, but little is known yet about human neurotoxicity under such situations and about strategies of neuronal rescue. To address this question, immortalized murine astrocytes (IMA) were combined with human LUHMES neurons and stimulated with an inflammatory (TNF, IL-1) cytokine mix (CM). Neurotoxicity was studied both in co-cultures and in monocultures after transfer of conditioned medium from activated IMA. Interventions with >20 drugs were used to profile the model system. Control IMA supported neurons and protected them from neurotoxicants. Inflammatory activation reduced this protection, and prolonged exposure of co-cultures to CM triggered neurotoxicity. Neither the added cytokines nor the release of NO from astrocytes were involved in this neurodegeneration. The neurotoxicity-mediating effect of IMA was faithfully reproduced by human astrocytes. Moreover, glia-dependent toxicity was also observed, when IMA cultures were stimulated with CM, and the culture medium was transferred to neurons. Such neurotoxicity was prevented when astrocytes were treated by p38 kinase inhibitors or dexamethasone, whereas such compounds had no effect when added to neurons. Conversely, treatment of neurons with five different drugs, including resveratrol and CEP1347, prevented toxicity of astrocyte supernatants. Thus, the sequential IMA-LUHMES neuroinflammation model is suitable for separate profiling of both glial-directed and directly neuroprotective strategies. Moreover, direct evaluation in co-cultures of the same cells allows for testing of therapeutic effectiveness in more complex settings, in which astrocytes affect pharmacological properties of neurons.
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Huang Z, Cheng C, Jiang L, Yu Z, Cao F, Zhong J, Guo Z, Sun X. Intraventricular apolipoprotein ApoJ infusion acts protectively in Traumatic Brain Injury. J Neurochem 2016; 136:1017-25. [PMID: 26670094 DOI: 10.1111/jnc.13491] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Revised: 11/24/2015] [Accepted: 12/04/2015] [Indexed: 11/29/2022]
Affiliation(s)
- Zhijian Huang
- Department of Neurosurgery; the First Affiliated Hospital of Chongqing Medical University; Chongqing China
| | - Chongjie Cheng
- Department of Neurosurgery; the First Affiliated Hospital of Chongqing Medical University; Chongqing China
| | - Li Jiang
- Department of Neurosurgery; the First Affiliated Hospital of Chongqing Medical University; Chongqing China
| | - Zhanyang Yu
- Department of Neurology and Radiology; Neuroprotection Research Laboratory; Harvard Medical School; Cambridge MA USA
| | - Fang Cao
- Department of Cerebrovascular; the Affiliated Hospital of Zunyi Medical College; Guizhou China
| | - Jianjun Zhong
- Department of Neurosurgery; the First Affiliated Hospital of Chongqing Medical University; Chongqing China
| | - Zongduo Guo
- Department of Neurosurgery; the First Affiliated Hospital of Chongqing Medical University; Chongqing China
| | - Xiaochuan Sun
- Department of Neurosurgery; the First Affiliated Hospital of Chongqing Medical University; Chongqing China
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Benedet AL, Labbe A, Lemay P, Zimmer ER, Pascoal TA, Leuzy A, Mathotaarachchi S, Mohades S, Shin M, Dionne-Laporte A, Beaudry T, Picard C, Gauthier S, Poirier J, Rouleau G, Rosa-Neto P. Epistasis analysis links immune cascades and cerebral amyloidosis. J Neuroinflammation 2015; 12:227. [PMID: 26626881 PMCID: PMC4666175 DOI: 10.1186/s12974-015-0436-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 11/16/2015] [Indexed: 12/21/2022] Open
Abstract
Background Several lines of evidence suggest the involvement of neuroinflammatory changes in Alzheimer’s disease (AD) pathophysiology such as amyloidosis and neurodegeneration. In fact, genome-wide association studies (GWAS) have shown a link between genes involved in neuroinflammation and AD. In order to further investigate whether interactions between candidate genetic variances coding for neuroinflammatory molecules are associated with brain amyloid β (Aβ) fibrillary accumulation, we conducted an epistasis analysis on a pool of genes associated with molecular mediators of inflammation. Methods [18F]Florbetapir positron emission tomography (PET) imaging was employed to assess brain Aβ levels in 417 participants from ADNI-GO/2 and posteriorly 174 from ADNI-1. IL-1β, IL4, IL6, IL6r, IL10, IL12, IL18, C5, and C9 genes were chosen based on previous studies conducted in AD patients. Using the [18F]florbetapir standardized uptake value ratio (SUVR) as a quantitative measure of fibrillary Aβ, epistasis analyses were performed between two sets of markers of immune-related genes using gender, diagnosis, and apolipoprotein E (APOE) as covariates. Voxel-based analyses were also conducted. The results were corrected for multiple comparison tests. Cerebrospinal fluid (CSF) Aβ1-42/phosphorylated tau (p-tau) ratio concentrations were used to confirm such associations. Results Epistasis analysis unveiled two significant single nucleotide polymorphism (SNP)-SNP interactions (false discovery rate (FDR) threshold 0.1), both interactions between C9 gene (rs261752) and IL6r gene (rs4240872, rs7514452). In a combined sample, the interactions were confirmed (p ≤ 10–5) and associated with amyloid accumulation within cognitively normal and AD spectrum groups. Voxel-based analysis corroborated initial findings. CSF biomarker (Aβ1-42/p-tau) confirmed the genetic interaction. Additionally, rs4240872 and rs7514452 SNPs were shown to be associated with CSF and plasma concentrations of IL6r protein. Conclusions Certain allele combinations involving IL6r and C9 genes are associated with Aβ burden in the brain. Hypothesis-driven search for epistasis is a valuable strategy for investigating imaging endophenotypes in complex neurodegenerative diseases. Electronic supplementary material The online version of this article (doi:10.1186/s12974-015-0436-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andréa L Benedet
- Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, 6825 LaSalle Blvd, H4H 1R3, Montreal, QC, Canada. .,CAPES Foundation, Ministry of Education of Brazil, Brasília, Brazil.
| | - Aurélie Labbe
- Douglas Hospital Research Centre, McGill University, Montreal, Canada. .,Department of Epidemiology, Biostatistics & Occupational Health, McGill University, Montreal, Canada. .,Department of Psychiatry, McGill University, Montreal, Canada.
| | - Philippe Lemay
- Department of Biochemistry, Université de Montréal, Montréal, Canada.
| | - Eduardo R Zimmer
- Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, 6825 LaSalle Blvd, H4H 1R3, Montreal, QC, Canada. .,Department of Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil. .,Brain Institute of Rio Grande do Sul (BraIns), Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Brazil.
| | - Tharick A Pascoal
- Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, 6825 LaSalle Blvd, H4H 1R3, Montreal, QC, Canada.
| | - Antoine Leuzy
- Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, 6825 LaSalle Blvd, H4H 1R3, Montreal, QC, Canada. .,Department of NVS, Center for Alzheimer Research, Translational Alzheimer Neurobiology, Karolinska Institutet, Stockholm, Sweden. .,Alzheimer's Disease Research Unit, McGill University Research Centre for Studies in Aging, McGill University, Montreal, Canada.
| | - Sulantha Mathotaarachchi
- Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, 6825 LaSalle Blvd, H4H 1R3, Montreal, QC, Canada.
| | - Sara Mohades
- Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, 6825 LaSalle Blvd, H4H 1R3, Montreal, QC, Canada.
| | - Monica Shin
- Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, 6825 LaSalle Blvd, H4H 1R3, Montreal, QC, Canada.
| | - Alexandre Dionne-Laporte
- Department of Neurology and Neurosurgery, McGill University, Montreal, Canada. .,Montreal Neurological Institute, Montreal, Canada.
| | - Thomas Beaudry
- Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, 6825 LaSalle Blvd, H4H 1R3, Montreal, QC, Canada.
| | - Cynthia Picard
- Douglas Hospital Research Centre, McGill University, Montreal, Canada.
| | - Serge Gauthier
- Department of Neurology and Neurosurgery, McGill University, Montreal, Canada.
| | - Judes Poirier
- Douglas Hospital Research Centre, McGill University, Montreal, Canada. .,Alzheimer's Disease Research Unit, McGill University Research Centre for Studies in Aging, McGill University, Montreal, Canada. .,Department of Neurology and Neurosurgery, McGill University, Montreal, Canada.
| | - Guy Rouleau
- Department of Neurology and Neurosurgery, McGill University, Montreal, Canada. .,Montreal Neurological Institute, Montreal, Canada.
| | - Pedro Rosa-Neto
- Translational Neuroimaging Laboratory, McGill University Research Centre for Studies in Aging, 6825 LaSalle Blvd, H4H 1R3, Montreal, QC, Canada. .,Alzheimer's Disease Research Unit, McGill University Research Centre for Studies in Aging, McGill University, Montreal, Canada. .,Department of Neurology and Neurosurgery, McGill University, Montreal, Canada. .,Montreal Neurological Institute, Montreal, Canada.
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Needleman LA, McAllister AK. The major histocompatibility complex and autism spectrum disorder. Dev Neurobiol 2012; 72:1288-301. [PMID: 22760919 PMCID: PMC4365477 DOI: 10.1002/dneu.22046] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 06/22/2012] [Indexed: 01/02/2023]
Abstract
Autism spectrum disorder (ASD) is a complex disorder that appears to be caused by interactions between genetic changes and environmental insults during early development. A wide range of factors have been linked to the onset of ASD, but recently both genetic associations and environmental factors point to a central role for immune-related genes and immune responses to environmental stimuli. Specifically, many of the proteins encoded by the major histocompatibility complex (MHC) play a vital role in the formation, refinement, maintenance, and plasticity of the brain. Manipulations of levels of MHC molecules have illustrated how disrupted MHC signaling can significantly alter brain connectivity and function. Thus, an emerging hypothesis in our field is that disruptions in MHC expression in the developing brain caused by mutations and/or immune dysregulation may contribute to the altered brain connectivity and function characteristic of ASD. This review provides an overview of the structure and function of the three classes of MHC molecules in the immune system, healthy brain, and their possible involvement in ASD.
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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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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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Fuller S, Steele M, Münch G. Activated astroglia during chronic inflammation in Alzheimer's disease--do they neglect their neurosupportive roles? Mutat Res 2010; 690:40-49. [PMID: 19748514 DOI: 10.1016/j.mrfmmm.2009.08.016] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 08/08/2009] [Accepted: 08/15/2009] [Indexed: 05/28/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder, characterized histopathologically by the extracellular deposition of beta-amyloid peptide in senile plaques, as well as intracellular neurofibrillary tangles (NFT) of hyperphosphorylated tau protein, extensive neuronal loss and synaptic changes in the hippocampus and cerebral cortex. In addition, the AD brain shows chronic inflammation characterized by an abundance of reactive astrocytes and activated microglia. In the healthy brain, astrocytes provide essential services for brain homeostasis and neuronal function, including metabolic support for neurons in the form of lactate, glutamate uptake and conversion into glutamine, and synthesis of glutathione and its precursors. In AD, a large body of evidence now suggests that by transforming from a basal to a reactive state, astrocytes neglect their neurosupportive functions, thus rendering neurons vulnerable to neurotoxins including pro-inflammatory cytokines and reactive oxygen species. This review will explain the normal functions of astrocytes, and how these cells might be activated to turn into inflammatory cells, actively contributing to neurodegeneration and neglecting their neurosupportive roles ("neuro-neglect hypothesis"). Furthermore, it is proposed that astrocytes might be promising target of therapeutic intervention for Alzheimer's disease, if these compromised functions can be normalized with pharmacological agents that are specifically designed to return astrocytes to a quiescent phenotype or supplement factors which activated astrocytes lack to produce.
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Affiliation(s)
- Stacey Fuller
- Department of Pharmacology, School of Medicine, University of Western Sydney, Campbelltown, Australia
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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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18
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Nguyen HX, Galvan MD, Anderson AJ. Characterization of early and terminal complement proteins associated with polymorphonuclear leukocytes in vitro and in vivo after spinal cord injury. J Neuroinflammation 2008; 5:26. [PMID: 18578885 PMCID: PMC2443364 DOI: 10.1186/1742-2094-5-26] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2008] [Accepted: 06/25/2008] [Indexed: 02/01/2023] Open
Abstract
Background The complement system has been suggested to affect injury or disease of the central nervous system (CNS) by regulating numerous physiological events and pathways. The activation of complement following traumatic CNS injury can also result in the formation and deposition of C5b-9 membrane attack complex (C5b-9/MAC), causing cell lysis or sublytic effects on vital CNS cells. Although complement proteins derived from serum/blood-brain barrier breakdown can contribute to injury or disease, infiltrating immune cells may represent an important local source of complement after injury. As the first immune cells to infiltrate the CNS within hours post-injury, polymorphonuclear leukocytes (PMNs) may affect injury through mechanisms associated with complement-mediated events. However, the expression/association of both early and terminal complement proteins by PMNs has not been fully characterized in vitro, and has not observed previously in vivo after traumatic spinal cord injury (SCI). Method We investigated the expression of complement mRNAs using rt-PCR and the presence of complement proteins associated with PMNs using immunofluroescence and quantitative flow cytometry. Results Stimulated or unstimulated PMNs expressed mRNAs encoding for C1q, C3, and C4, but not C5, C6, C7 or C9 in culture. Complement protein C1q or C3 was also detected in less than 30% of cultured PMNs. In contrast, over 70% of PMNs that infiltrated the injured spinal cord were associated with C1q, C3, C7 and C5b-9/MAC 3 days post-SCI. The localization/association of C7 or C5b-9/MAC with infiltrating PMNs in the injured spinal cord suggests the incorporation or internalization of C7 or C5b-9/MAC bound cellular debris by infiltrating PMNs because C7 and C5b-9/MAC were mostly localized to granular vesicles within PMNs at the spinal cord epicenter region. Furthermore, PMN presence in the injured spinal cord was observed for many weeks post-SCI, suggesting that this infiltrating cell population could chronically affect complement-mediated events and SCI pathogenesis after trauma. Conclusion Data presented here provide the first characterization of early and terminal complement proteins associated with PMNs in vitro and in vivo after SCI. Data also suggest a role for PMNs in the local internalization or deliverance of complement and complement activation in the post-SCI environment.
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Affiliation(s)
- Hal X Nguyen
- Physical Medicine & Rehabilitation, 1105 Gillespie Neuroscience Research Facility, University of California, Irvine, CA 92697-4292, USA.
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Walker DG, Dalsing-Hernandez JE, Lue LF. Human postmortem brain-derived cerebrovascular smooth muscle cells express all genes of the classical complement pathway: a potential mechanism for vascular damage in cerebral amyloid angiopathy and Alzheimer's disease. Microvasc Res 2007; 75:411-9. [PMID: 18048067 DOI: 10.1016/j.mvr.2007.10.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2006] [Revised: 09/27/2007] [Accepted: 10/12/2007] [Indexed: 10/22/2022]
Abstract
Deposition of amyloid around blood vessels, known as cerebral amyloid angiopathy (CAA), is a major pathological feature found in the majority of Alzheimer's disease (AD) cases, and activated complement fragments have been detected on CAA deposits in AD brains. In this study, we demonstrate for the first time that human cerebrovascular smooth muscle cells (HCSMC) isolated from cortical vessels derived from postmortem brains can express mRNAs for complement genes C1qB, C1r, C1s, C2, C3, C4, C5, C6, C7, C8 and C9, the components of the classical complement pathway. Secretion of the corresponding complement proteins for these genes was also demonstrated, except for C1q and C5. Of particular significance was the observation that treatment of HCSMC with aggregated amyloid beta (Abeta) 1-42 increased expression of complement C3 mRNA and increased release of C3 protein. Abeta treatment of HCSMC also increased expression of C6 mRNA. Interferon-gamma induced expression and release of complement C1r, C1s, C2 and C4. As HCSMC are closely associated with Abeta deposits in vessels in the brain, their production of complement proteins could amplify the proinflammatory effects of amyloid in the perivascular environment, further compromising brain vascular integrity.
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MESH Headings
- Aged, 80 and over
- Alzheimer Disease/metabolism
- Alzheimer Disease/pathology
- Amyloid beta-Peptides/pharmacology
- Brain/blood supply
- Cadaver
- Cells, Cultured
- Cerebral Amyloid Angiopathy/metabolism
- Cerebral Amyloid Angiopathy/pathology
- Complement System Proteins/genetics
- Complement System Proteins/metabolism
- Culture Media, Conditioned/chemistry
- Culture Media, Conditioned/metabolism
- Gene Expression
- Humans
- Interferon-gamma/pharmacology
- Muscle, Smooth, Vascular/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Myocytes, Smooth Muscle/pathology
- Postmortem Changes
- RNA, Messenger/metabolism
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Affiliation(s)
- Douglas G Walker
- Laboratory of Neuroinflammation, Sun Health Research Institute, Sun City, Arizona, USA.
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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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Timár KK, Dallos A, Kiss M, Husz S, Bos JD, Asghar SS. Expression of terminal complement components by human keratinocytes. Mol Immunol 2007; 44:2578-86. [PMID: 17267037 DOI: 10.1016/j.molimm.2006.12.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 12/10/2006] [Accepted: 12/14/2006] [Indexed: 11/16/2022]
Abstract
Human keratinocytes are important constituents of the skin immune system. They produce several cytokines, chemokines as well as some complement proteins. As regards soluble complement proteins, so far keratinocytes have been shown to synthesize only C3, factor B, factor H and factor I. Synthesis and regulation of synthesis of other complement proteins has not yet been studied. Here we studied the synthesis of terminal complement components, C5-C9 by human keratinocytes. We also studied the regulation of terminal complement synthesis in keratinocytes by several cytokines, namely, IL-1alpha, IL-2, IL-6, TGF-beta1, TNF-alpha, and IFN-gamma. Human keratinocytes constitutively expressed C5, C7, C8gamma and C9 mRNA but not C6, C8alpha and C8beta mRNA. They released C7 and C9, but not C5, C6 and C8. None of the cytokines tested had any influence on the synthesis of terminal components except TNF-alpha, which strongly upregulated C9 production. In conclusion, we demonstrate that keratinocytes are capable of synthesizing some of the terminal complement components and that the synthesis of C9 is regulated by TNF-alpha.
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Affiliation(s)
- Krisztina K Timár
- Department of Dermatology, Academic Medical Center, University of Amsterdam, P.O. Box 22700, 1100 DE Amsterdam, The Netherlands.
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Hosokawa M, Klegeris A, McGeer PL. Human oligodendroglial cells express low levels of C1 inhibitor and membrane cofactor protein mRNAs. J Neuroinflammation 2004; 1:17. [PMID: 15327690 PMCID: PMC516791 DOI: 10.1186/1742-2094-1-17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2004] [Accepted: 08/24/2004] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND: Oligodendrocytes, neurons, astrocytes, microglia, and endothelial cells are capable of synthesizing complement inhibitor proteins. Oligodendrocytes are vulnerable to complement attack, which is particularly observed in multiple sclerosis. This vulnerability may be related to a deficiency in their ability to express complement regulatory proteins. METHODS: This study compared the expression level of complement inhibitor mRNAs by human oligodendrocytes, astrocytes and microglia using semi-quantitative RT-PCR. RESULTS: Semi-quantitative RT-PCR analysis showed that C1 inhibitor (C1-inh) mRNA expression was dramatically lower in oligodendroglial cells compared with astrocytes and microglia. The mRNA expression level of membrane cofactor protein (MCP) by oligodendrocytes was also significantly lower than for other cell types. CONCLUSION: The lower mRNA expression of C1-inh and MCP by oligodendrocytes could contribute to their vulnerability in several neurodegenerative and inflammatory diseases of the central nervous system.
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Affiliation(s)
- Masato Hosokawa
- Kinsmen Laboratory of Neurological Research, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Andis Klegeris
- Kinsmen Laboratory of Neurological Research, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Patrick L McGeer
- Kinsmen Laboratory of Neurological Research, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, V6T 1Z3, Canada
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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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Xu X, Joh HD, Pin S, Schiller NI, Prange C, Burger PC, Schiller MR. Expression of multiple larger-sized transcripts for several genes in oligodendrogliomas: potential markers for glioma subtype. Cancer Lett 2001; 171:67-77. [PMID: 11485829 DOI: 10.1016/s0304-3835(01)00573-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Astrocytomas and oligodendrogliomas are two brain tumors that follow different clinical courses. Although many of these tumors can be identified based on standard histopathological criteria, a significant percentage present notable problems in diagnosis. To identify markers that might prove useful in distinguishing glioma subtypes, we prepared and analyzed cDNA libraries for differential expression of genes in an astrocytoma (grade II), an oligodendroglioma (grade II), and a meningioma (benign). The tumor libraries were compared by sequencing randomly selected clones and tabulating the expression frequency of each gene. In addition to identifying several genes previously reported or expected to be differentially expressed among these tumors, several potential new brain tumor markers were identified and confirmed by Northern blot analysis of a panel of brain tumors. A surprising result of this analysis was the observation that several larger-sized transcripts for various genes were predominantly expressed in the oligodendroglioma tumors, when compared to the other brain tumors or in non-tumor gray matter. These findings are consistent with different pre-mRNA splicing patterns observed between oligodendrogliomas and astrocytomas. In support of this hypothesis, our screen revealed significantly higher levels of two hnRNP A1 transcripts in oligodendrogliomas. hnRNP A1 is a component of the spliceosome whose expression levels affect splice site selection in vivo. The preferential expression of larger-sized transcripts for several genes in oligodendrogliomas may be useful for distinguishing astrocytic and oligodendroglial gliomas.
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Affiliation(s)
- X Xu
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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25
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Klegeris A, Schwab C, Bissonnette CJ, McGeer PL. Induction of complement C9 messenger RNAs in human neuronal cells by inflammatory stimuli: relevance to neurodegenerative disorders. Exp Gerontol 2001; 36:1179-88. [PMID: 11404058 DOI: 10.1016/s0531-5565(00)00265-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Neurons express proteins of the classical complement pathway, including C9. Both the mRNA and protein levels for C9 are sharply upregulated in brain areas affected by Alzheimer's disease (AD). Since little is known about the signals that are responsible for this upregulation, we evaluated in human SH-SY5Y neuroblastoma cells the factors which stimulate C9 production. Interferon-gamma, phorbol myristate acetate and interleukin-6 all stimulated C9 mRNA expression but the inflammatory cytokines tumor necrosis factor-alpha, interleukin-1 beta, as well as the anaphylatoxin C5a and the bacterial lipopolysaccharide, were ineffective. Immunohistochemical analysis of postmortem human brains for C9 protein demonstrated its presence in many cortical pyramidal neurons in AD, Down's syndrome, the parkinsonism dementia complex of Guam and pallido-ponto-nigral degeneration, as well as in thalamic neurons of progressive supranuclear palsy and ballooned neurons of Pick's disease. Since C9 is required for the membrane attack complex of complement to become functional, interfering with signaling pathways that stimulate its production could offer new therapeutic strategies for treating various neurodegenerative disorders.
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Affiliation(s)
- A Klegeris
- Department of Psychiatry, Kinsmen Laboratory of Neurological Research, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, Canada V6T 1Z3
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26
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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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27
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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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Lee YB, Schrader JW, Kim SU. p38 map kinase regulates TNF-alpha production in human astrocytes and microglia by multiple mechanisms. Cytokine 2000; 12:874-80. [PMID: 10880231 DOI: 10.1006/cyto.2000.0688] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In the vertebrate central nervous system (CNS), tumour necrosis factor-alpha (TNF-alpha) is produced by astrocytes and microglia and mediates cell injury in nerve cells and oligodendrocytes. In the present study, we have used a specific inhibitor of p38 MAP kinase, SB203580 to examine the role of p38 MAP kinase in regulation of TNF-alpha production in human astrocytes and microglia in terms of levels of mRNA and secreted protein. A reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed that increased levels of TNF-alpha mRNA were induced in astrocytes by IL-1beta treatment, and in microglia by bacterial lipopolysaccharide (LPS). In microglia, treatment with SB203580 reduced the level of TNF-alpha mRNA, but in astrocytes it did not. However, the secretion of TNF-alpha by both astrocytes and microglia was markedly inhibited by SB203580 at a low concentration. TNF-alpha secretion was reduced approximately 80% in astrocytes and 85% in microglia. The results demonstrate a key role played by p38 MAP kinase in upregulation of TNF-alpha mRNA levels in LPS-activated human microglia, whereas p38 MAP kinase is involved in post-transcriptional regulation of TNF-alpha production at translational level in IL-1beta-activated human astrocytes.
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Affiliation(s)
- Y B Lee
- Division of Neurology, University of British Columbia, Vancouver, Canada
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