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Passarelli JP, Nimjee SM, Townsend KL. Stroke and Neurogenesis: Bridging Clinical Observations to New Mechanistic Insights from Animal Models. Transl Stroke Res 2024; 15:53-68. [PMID: 36462099 DOI: 10.1007/s12975-022-01109-1] [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: 10/13/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 12/04/2022]
Abstract
Stroke was the 2nd leading cause of death and a major cause of morbidity. Unfortunately, there are limited means to promote neurological recovery post-stroke, but research has unearthed potential targets for therapies to encourage post-stroke neurogenesis and neuroplasticity. The occurrence of neurogenesis in adult mammalian brains, including humans, was not widely accepted until the 1990s. Now, adult neurogenesis has been extensively studied in human and mouse neurogenic brain niches, of which the subventricular zone of the lateral ventricles and subgranular zone of the dentate gyrus are best studied. Numerous other niches are under investigation for neurogenic potential. This review offers a basic overview to stroke in the clinical setting, a focused summary of recent and foundational research literature on cortical neurogenesis and post-stroke brain plasticity, and insights regarding how the meninges and choroid plexus have emerged as key players in neurogenesis and neuroplasticity in the context of focal cerebral ischemia disrupting the anterior circulation. The choroid plexus and meninges are vital as they are integral sites for neuroimmune interactions, glymphatic perfusion, and niche signaling pertinent to neural stem cells and neurogenesis. Modulating neuroimmune interactions with a focus on astrocyte activity, potentially through manipulation of the choroid plexus and meningeal niches, may reduce the exacerbation of stroke by inflammatory mediators and create an environment conducive to neurorecovery. Furthermore, addressing impaired glymphatic perfusion after ischemic stroke likely supports a neurogenic environment by clearing out inflammatory mediators, neurotoxic metabolites, and other accumulated waste. The meninges and choroid plexus also contribute more directly to promoting neurogenesis: the meninges are thought to harbor neural stem cells and are a niche amenable to neural stem/progenitor cell migration. Additionally, the choroid plexus has secretory functions that directly influences stem cells through signaling mechanisms and growth factor actions. More research to better understand the functions of the meninges and choroid plexus may lead to novel approaches for stimulating neuronal recovery after ischemic stroke.
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Affiliation(s)
| | - Shahid M Nimjee
- Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Biomedical Research Tower, 460 W 12th Avenue, Columbus, OH, 43210, USA
| | - Kristy L Townsend
- Department of Neurological Surgery, The Ohio State University Wexner Medical Center, Biomedical Research Tower, 460 W 12th Avenue, Columbus, OH, 43210, USA.
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2
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Gong Z, Guo J, Liu B, Guo Y, Cheng C, Jiang Y, Liang N, Hu M, Song T, Yang L, Li H, Zhang H, Zong X, Che Q, Shi N. Mechanisms of immune response and cell death in ischemic stroke and their regulation by natural compounds. Front Immunol 2024; 14:1287857. [PMID: 38274789 PMCID: PMC10808662 DOI: 10.3389/fimmu.2023.1287857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2023] [Accepted: 12/26/2023] [Indexed: 01/27/2024] Open
Abstract
Ischemic stroke (IS), which is the third foremost cause of disability and death worldwide, has inflammation and cell death as its main pathological features. IS can lead to neuronal cell death and release factors such as damage-related molecular patterns, stimulating the immune system to release inflammatory mediators, thereby resulting in inflammation and exacerbating brain damage. Currently, there are a limited number of treatment methods for IS, which is a fact necessitating the discovery of new treatment targets. For this review, current research on inflammation and cell death in ischemic stroke was summarized. The complex roles and pathways of the principal immune cells (microglia, astrocyte, neutrophils, T lymphocytes, and monocytes/macrophage) in the immune system after IS in inflammation are discussed. The mechanisms of immune cell interactions and the cytokines involved in these interactions are summarized. Moreover, the cell death mechanisms (pyroptosis, apoptosis, necroptosis, PANoptosis, and ferroptosis) and pathways after IS are explored. Finally, a summary is provided of the mechanism of action of natural pharmacological active ingredients in the treatment of IS. Despite significant recent progress in research on IS, there remain many challenges that need to be overcome.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | - Qianzi Che
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China
| | - Nannan Shi
- Institute of Basic Research in Clinical Medicine, China Academy of Chinese Medical Sciences, Beijing, China
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3
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Ghosh M, Rana S. The anaphylatoxin C5a: Structure, function, signaling, physiology, disease, and therapeutics. Int Immunopharmacol 2023; 118:110081. [PMID: 36989901 DOI: 10.1016/j.intimp.2023.110081] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Revised: 03/06/2023] [Accepted: 03/21/2023] [Indexed: 03/30/2023]
Abstract
The complement system is one of the oldest known tightly regulated host defense systems evolved for efficiently functioning cell-based immune systems and antibodies. Essentially, the complement system acts as a pivot between the innate and adaptive arms of the immune system. The complement system collectively represents a cocktail of ∼50 cell-bound/soluble glycoproteins directly involved in controlling infection and inflammation. Activation of the complement cascade generates complement fragments like C3a, C4a, and C5a as anaphylatoxins. C5a is the most potent proinflammatory anaphylatoxin, which is involved in inflammatory signaling in a myriad of tissues. This review provides a comprehensive overview of human C5a in the context of its structure and signaling under several pathophysiological conditions, including the current and future therapeutic applications targeting C5a.
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Affiliation(s)
- Manaswini Ghosh
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Odisha 752050, India
| | - Soumendra Rana
- Chemical Biology Laboratory, School of Basic Sciences, Indian Institute of Technology Bhubaneswar, Odisha 752050, India.
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4
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C3aR in astrocytes mediates post-thoracotomy pain by inducing A1 astrocytes in male rats. Biochim Biophys Acta Mol Basis Dis 2023; 1869:166672. [PMID: 36871753 DOI: 10.1016/j.bbadis.2023.166672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 02/21/2023] [Accepted: 02/21/2023] [Indexed: 03/07/2023]
Abstract
BACKGROUND Astrocyte activation, which is polarized into classical neurotoxic A1, neuroprotective A2, A-pan, etc., is thought to be involved in the transition from acute to chronic post-thoracotomy pain. The C3aR receptor associated with astrocyte-neuron and -microglia interactions is necessary for A1 astrocytes polarization. This study aimed to determine whether C3aR in astrocytes mediates post-thoracotomy pain by inducing A1 expression in a rat thoracotomy pain model. METHODS A rat thoracotomy pain model was employed. The mechanical withdraw threshold was measured to evaluate pain behavior. Lipopolysaccharide (LPS) was injected intraperitoneally to induce A1. Intrathecal injection of AAV2/9-rC3ar1 shRNA-GFAP was used to knock down in vivo C3aR expression in astrocytes. The expression of associated phenotypic markers before and after intervention was assessed by RT-PCR, western blot, co-immunofluorescence, and single-cell RNA sequencing. RESULTS C3aR downregulation was found to inhibit LPS-induced A1 astrocytes activation, decrease the expression of C3aR, C3, and GFAP, which were activated from acute to chronic pain, and alleviate the mechanical withdrawal threshold and chronic pain incidence. In addition, more A2 astrocytes were activated in the model group that did not develop chronic pain. C3aR downregulation increased the number of A2 astrocytes upon LPS exposure. Knockdown of C3aR also decreased the activation of M1 microglia induced by LPS or thoracotomy. CONCLUSIONS Our study confirmed that C3aR-induced A1 polarization contributes to chronic post-thoracotomy pain. Inhibition of A1 activation via C3aR downregulation increases anti-inflammatory A2 and decreases pro-inflammatory M1 activation, which may also be involved in the mechanism of chronic post-thoracotomy pain.
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5
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Westacott LJ, Wilkinson LS. Complement Dependent Synaptic Reorganisation During Critical Periods of Brain Development and Risk for Psychiatric Disorder. Front Neurosci 2022; 16:840266. [PMID: 35600620 PMCID: PMC9120629 DOI: 10.3389/fnins.2022.840266] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 03/09/2022] [Indexed: 12/12/2022] Open
Abstract
We now know that the immune system plays a major role in the complex processes underlying brain development throughout the lifespan, carrying out a number of important homeostatic functions under physiological conditions in the absence of pathological inflammation or infection. In particular, complement-mediated synaptic pruning during critical periods of early life may play a key role in shaping brain development and subsequent risk for psychopathology, including neurodevelopmental disorders such as schizophrenia and autism spectrum disorders. However, these disorders vary greatly in their onset, disease course, and prevalence amongst sexes suggesting complex interactions between the immune system, sex and the unique developmental trajectories of circuitries underlying different brain functions which are yet to be fully understood. Perturbations of homeostatic neuroimmune interactions during different critical periods in which regional circuits mature may have a plethora of long-term consequences for psychiatric phenotypes, but at present there is a gap in our understanding of how these mechanisms may impact on the structural and functional changes occurring in the brain at different developmental stages. In this article we will consider the latest developments in the field of complement mediated synaptic pruning where our understanding is beginning to move beyond the visual system where this process was first described, to brain areas and developmental periods of potential relevance to psychiatric disorders.
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Affiliation(s)
- Laura J. Westacott
- Neuroscience and Mental Health Innovation Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Cardiff University, Cardiff, United Kingdom
- Hodge Centre for Neuropsychiatric Immunology, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - Lawrence S. Wilkinson
- Neuroscience and Mental Health Innovation Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Cardiff University, Cardiff, United Kingdom
- Hodge Centre for Neuropsychiatric Immunology, School of Medicine, Cardiff University, Cardiff, United Kingdom
- Behavioural Genetics Group, Schools of Psychology and Medicine, Cardiff University, Cardiff, United Kingdom
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6
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Devasani K, Yao Y. Expression and functions of adenylyl cyclases in the CNS. Fluids Barriers CNS 2022; 19:23. [PMID: 35307032 PMCID: PMC8935726 DOI: 10.1186/s12987-022-00322-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Accepted: 03/07/2022] [Indexed: 12/27/2022] Open
Abstract
Adenylyl cyclases (ADCYs), by generating second messenger cAMP, play important roles in various cellular processes. Their expression, regulation and functions in the CNS, however, remain largely unknown. In this review, we first introduce the classification and structure of ADCYs, followed by a discussion of the regulation of mammalian ADCYs (ADCY1-10). Next, the expression and function of each mammalian ADCY isoform are summarized in a region/cell-specific manner. Furthermore, the effects of GPCR-ADCY signaling on blood-brain barrier (BBB) integrity are reviewed. Last, current challenges and future directions are discussed. We aim to provide a succinct review on ADCYs to foster new research in the future.
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Affiliation(s)
- Karan Devasani
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., MDC 8, Tampa, FL, 33612, USA
| | - Yao Yao
- Department of Molecular Pharmacology and Physiology, Morsani College of Medicine, University of South Florida, 12901 Bruce B. Downs Blvd., MDC 8, Tampa, FL, 33612, USA.
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7
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Westacott LJ, Humby T, Haan N, Brain SA, Bush EL, Toneva M, Baloc AI, Moon AL, Reddaway J, Owen MJ, Hall J, Hughes TR, Morgan BP, Gray WP, Wilkinson LS. Complement C3 and C3aR mediate different aspects of emotional behaviours; relevance to risk for psychiatric disorder. Brain Behav Immun 2022; 99:70-82. [PMID: 34543680 DOI: 10.1016/j.bbi.2021.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Revised: 09/03/2021] [Accepted: 09/13/2021] [Indexed: 12/18/2022] Open
Abstract
Complement is a key component of the immune system with roles in inflammation and host-defence. Here we reveal novel functions of complement pathways impacting on emotional reactivity of potential relevance to the emerging links between complement and risk for psychiatric disorder. We used mouse models to assess the effects of manipulating components of the complement system on emotionality. Mice lacking the complement C3a Receptor (C3aR-/-) demonstrated a selective increase in unconditioned (innate) anxiety whilst mice deficient in the central complement component C3 (C3-/-) showed a selective increase in conditioned (learned) fear. The dissociable behavioural phenotypes were linked to different signalling mechanisms. Effects on innate anxiety were independent of C3a, the canonical ligand for C3aR, consistent with the existence of an alternative ligand mediating innate anxiety, whereas effects on learned fear were due to loss of iC3b/CR3 signalling. Our findings show that specific elements of the complement system and associated signalling pathways contribute differentially to heightened states of anxiety and fear commonly seen in psychopathology.
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Affiliation(s)
- Laura J Westacott
- Neuroscience and Mental Health Research Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Hadyn Ellis Building, Cardiff University, Cardiff CF24 4HQ, UK; Hodge Centre for Neuropsychiatric Immunology, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Trevor Humby
- Neuroscience and Mental Health Research Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Hadyn Ellis Building, Cardiff University, Cardiff CF24 4HQ, UK; Behavioural Genetics Group, Schools of Psychology and Medicine, Cardiff University, Cardiff CF10 3AT, UK
| | - Niels Haan
- Neuroscience and Mental Health Research Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Hadyn Ellis Building, Cardiff University, Cardiff CF24 4HQ, UK
| | - Sophie A Brain
- Behavioural Genetics Group, Schools of Psychology and Medicine, Cardiff University, Cardiff CF10 3AT, UK
| | - Emma-Louise Bush
- Behavioural Genetics Group, Schools of Psychology and Medicine, Cardiff University, Cardiff CF10 3AT, UK
| | - Margarita Toneva
- Institute of Psychiatry, Psychology and Neuroscience, King's College London, London SE5 8AF, UK
| | - Andreea-Ingrid Baloc
- Behavioural Genetics Group, Schools of Psychology and Medicine, Cardiff University, Cardiff CF10 3AT, UK
| | - Anna L Moon
- Neuroscience and Mental Health Research Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Hadyn Ellis Building, Cardiff University, Cardiff CF24 4HQ, UK
| | - Jack Reddaway
- Neuroscience and Mental Health Research Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Hadyn Ellis Building, Cardiff University, Cardiff CF24 4HQ, UK; Hodge Centre for Neuropsychiatric Immunology, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Michael J Owen
- Neuroscience and Mental Health Research Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Hadyn Ellis Building, Cardiff University, Cardiff CF24 4HQ, UK
| | - Jeremy Hall
- Neuroscience and Mental Health Research Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Hadyn Ellis Building, Cardiff University, Cardiff CF24 4HQ, UK; Hodge Centre for Neuropsychiatric Immunology, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - Timothy R Hughes
- Complement Biology Group, Systems Immunity Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XW, UK; Hodge Centre for Neuropsychiatric Immunology, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK
| | - B Paul Morgan
- Complement Biology Group, Systems Immunity Research Institute, School of Medicine, Cardiff University, Cardiff CF14 4XW, UK; Hodge Centre for Neuropsychiatric Immunology, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK; UK Dementia Research Institute, Cardiff University, Cardiff CF24 4HQ, UK
| | - William P Gray
- Neuroscience and Mental Health Research Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Hadyn Ellis Building, Cardiff University, Cardiff CF24 4HQ, UK; Hodge Centre for Neuropsychiatric Immunology, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK; Brain Repair and Intracranial Therapeutics (BRAIN) Unit, School of Medicine, Cardiff University, CF24 4HQ, UK
| | - Lawrence S Wilkinson
- Neuroscience and Mental Health Research Institute, MRC Centre for Neuropsychiatric Genetic and Genomics, School of Medicine, Hadyn Ellis Building, Cardiff University, Cardiff CF24 4HQ, UK; Behavioural Genetics Group, Schools of Psychology and Medicine, Cardiff University, Cardiff CF10 3AT, UK; Hodge Centre for Neuropsychiatric Immunology, School of Medicine, Cardiff University, Cardiff CF24 4HQ, UK.
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8
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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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9
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Han J, Zhang X. Complement Component C3: A Novel Biomarker Participating in the Pathogenesis of Non-alcoholic Fatty Liver Disease. Front Med (Lausanne) 2021; 8:653293. [PMID: 34395461 PMCID: PMC8358116 DOI: 10.3389/fmed.2021.653293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 07/07/2021] [Indexed: 12/16/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is currently the most common cause of chronic liver disorder worldwide. The pathological spectrum of NAFLD ranges from simple steatosis to non-alcoholic steatohepatitis (NASH) that induces progressive liver cirrhosis and eventually hepatocellular carcinoma (HCC). However, the molecular mechanisms driving the transformation of NASH are obscure. There is a compelling need for understanding the pathogenic mechanisms of NASH, and thereby providing new insight into mechanism-based therapy. Currently, several studies reported that complement system, an innate immune system, played an important role in the pathogenesis of NAFLD, which was also proved by our recent study. Complement component 3 (C3), a protein of the innate immune system, plays a hub role in the complement system. Herein, we present a review on the role and molecular mechanism of C3 in NASH as well as its implication in NASH diagnosis and treatment.
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Affiliation(s)
- Juqiang Han
- Institute of Liver Disease, The 7th Medical Centre of Chinese People Liberation Army General Hospital, Beijing, China.,The Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Institute of Digestive Disease, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China
| | - Xiang Zhang
- The Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Institute of Digestive Disease, Li Ka Shing Institute of Health Sciences, Chinese University of Hong Kong Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong, China
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10
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Pekna M, Pekny M. The Complement System: A Powerful Modulator and Effector of Astrocyte Function in the Healthy and Diseased Central Nervous System. Cells 2021; 10:cells10071812. [PMID: 34359981 PMCID: PMC8303424 DOI: 10.3390/cells10071812] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 07/08/2021] [Accepted: 07/14/2021] [Indexed: 12/11/2022] Open
Abstract
The complement system, an effector arm of the innate immune system that plays a critical role in tissue inflammation, the elimination of pathogens and the clearance of dead cells and cell debris, has emerged as a regulator of many processes in the central nervous system, including neural cell genesis and migration, control of synapse number and function, and modulation of glial cell responses. Complement dysfunction has also been put forward as a major contributor to neurological disease. Astrocytes are neuroectoderm-derived glial cells that maintain water and ionic homeostasis, and control cerebral blood flow and multiple aspects of neuronal functioning. By virtue of their expression of soluble as well as membrane-bound complement proteins and receptors, astrocytes are able to both send and receive complement-related signals. Here we review the current understanding of the multiple functions of the complement system in the central nervous system as they pertain to the modulation of astrocyte activity, and how astrocytes use the complement system to affect their environment in the healthy brain and in the context of neurological disease.
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Affiliation(s)
- Marcela Pekna
- Laboratory of Regenerative Neuroimmunology, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, 40530 Gothenburg, Sweden
- Florey Institute of Neuroscience and Mental Health, Parkville, Melbourne 3010, Australia
- School of Medicine and Public Health, University of Newcastle, Newcastle 2308, Australia
- Correspondence: ; Tel.: +46-31-786-3581
| | - Milos Pekny
- Laboratory of Astrocyte Biology and CNS Regeneration, Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, 40530 Gothenburg, Sweden;
- Florey Institute of Neuroscience and Mental Health, Parkville, Melbourne 3010, Australia
- School of Medicine and Public Health, University of Newcastle, Newcastle 2308, Australia
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11
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Propson NE, Gedam M, Zheng H. Complement in Neurologic Disease. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2020; 16:277-298. [PMID: 33234021 DOI: 10.1146/annurev-pathol-031620-113409] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Classic innate immune signaling pathways provide most of the immune response in the brain. This response activates many of the canonical signaling mechanisms identified in peripheral immune cells, despite their relative absence in this immune-privileged tissue. Studies over the past decade have strongly linked complement protein production and activation to age-related functional changes and neurodegeneration. The reactivation of the complement signaling pathway in aging and disease has opened new avenues for understanding brain aging and neurological disease pathogenesis and has implicated cell types such as astrocytes, microglia, endothelial cells, oligodendrocytes, neurons, and even peripheral immune cells in these processes. In this review, we aim to unravel the past decade of research related to complement activation and its numerous consequences in aging and neurological disease.
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Affiliation(s)
- Nicholas E Propson
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Manasee Gedam
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas 77030, USA.,Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Hui Zheng
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas 77030, USA.,Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, Texas 77030, USA.,Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA;
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12
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Laumonnier Y, Karsten CM, Köhl G, Köhl J. Characterization of Anaphylatoxin Receptor Expression and C3a/C5a Functions in Anaphylatoxin Receptor Reporter Mice. ACTA ACUST UNITED AC 2020; 130:e100. [PMID: 32710701 DOI: 10.1002/cpim.100] [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: 12/28/2022]
Abstract
The anaphylatoxins (AT) C3a and C5a are effector molecules of C3 and C5 exerting multiple biologic functions through binding and activation of their cognate G protein-coupled receptors. C3a interacts with the C3a receptor (C3aR), whereas C5a and its primary degradation product C5a-desArg engage C5aR1 and C5aR2. In the past, analysis of AT expression has been hampered by cross reaction of antibodies designed to recognize the different AT receptors. Furthermore, assessment of effects mediated by cell-specific activation has been difficult. Here, floxed AT receptor reporter mice are described as tools to monitor AT receptor expression in cells and tissues and to study the functions of C3a and C5a by cell-specific deletion of their cognate AT receptors. © 2020 The Authors. Basic Protocol 1: Genotyping of floxed GFP-C5aR1 knockin mice Support Protocol 1: Genotyping of LysMcre-C5ar1-/- mice Basic Protocol 2: Genotyping of floxed tdTomato-C3aR and -tdTomato-C5aR2 knockin mice Support Protocol 2: Preparation of genomic DNA Basic Protocol 3: Determination of C5aR1, C5aR2, and C3aR expression using floxed AT receptor reporter mice Support Protocol 3: Determination of C3aR expression using a C3aR-specific antibody Support Protocol 4: Determination of C5aR1, C5aR2, and C3aR mRNA expression in floxed GFP-C5aR1, floxed tdTomato-C5aR2 or -tdTomato C3aR positive cells Basic Protocol 4: Analysis of C5aR1-driven ERK1/2 phosphorylation in GFP-C5aR1+ cells Basic Protocol 5: Assessment of C3aR functions in cells obtained from floxed tdTomato-C3aR knockin mice- Determination of C3aR internalization Alternate Protocol: C3a-induced increase in intracellular Ca2+ Basic Protocol 6: C5aR2-driven IFN-γ production from NK cells Support Protocol 5: Isolation of splenic NK cells by FACS.
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Affiliation(s)
- Yves Laumonnier
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck, Germany
| | - Christian M Karsten
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck, Germany
| | - Gabriele Köhl
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck, Germany
| | - Jörg Köhl
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck, Germany.,Division of Immunobiology, Cincinnati Children's Hospital and University of Cincinnati College of Medicine, Cincinnati, Ohio
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13
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Pekny M, Wilhelmsson U, Tatlisumak T, Pekna M. Astrocyte activation and reactive gliosis-A new target in stroke? Neurosci Lett 2018; 689:45-55. [PMID: 30025833 DOI: 10.1016/j.neulet.2018.07.021] [Citation(s) in RCA: 133] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 07/03/2018] [Accepted: 07/14/2018] [Indexed: 11/27/2022]
Abstract
Stroke is an acute insult to the central nervous system (CNS) that triggers a sequence of responses in the acute, subacute as well as later stages, with prominent involvement of astrocytes. Astrocyte activation and reactive gliosis in the acute stage of stroke limit the tissue damage and contribute to the restoration of homeostasis. Astrocytes also control many aspects of neural plasticity that is the basis for functional recovery. Here, we discuss the concept of intermediate filaments (nanofilaments) and the complement system as two handles on the astrocyte responses to injury that both present attractive opportunities for novel treatment strategies modulating astrocyte functions and reactive gliosis.
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Affiliation(s)
- Milos Pekny
- Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Box 440, 40530 Gothenburg, Sweden; Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia; University of Newcastle, Newcastle, NSW, Australia.
| | - Ulrika Wilhelmsson
- Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Box 440, 40530 Gothenburg, Sweden
| | - Turgut Tatlisumak
- Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Box 440, 40530 Gothenburg, Sweden; Department of Neurology, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Marcela Pekna
- Center for Brain Repair, Department of Clinical Neuroscience, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, Box 440, 40530 Gothenburg, Sweden; Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia; University of Newcastle, Newcastle, NSW, Australia
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14
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Esen F, Orhun G, Ozcan PE, Senturk E, Kucukerden M, Giris M, Akcan U, Yilmaz CU, Orhan N, Arican N, Kaya M, Gazioglu SB, Tuzun E. Neuroprotective effects of intravenous immunoglobulin are mediated through inhibition of complement activation and apoptosis in a rat model of sepsis. Intensive Care Med Exp 2017; 5:1. [PMID: 28058672 PMCID: PMC5215999 DOI: 10.1186/s40635-016-0114-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 12/08/2016] [Indexed: 12/25/2022] Open
Abstract
Background Intravenous (IV) immunoglobulin (Ig) treatment is known to alleviate behavioral deficits and increase survival in the experimentally induced model of sepsis. To delineate the mechanisms by which IVIg treatment prevents neuronal dysfunction, an array of immunological and apoptosis markers was investigated. Methods Sepsis was induced by cecal ligation perforation (CLP) in rats. The animals were divided into five groups: sham, control, CLP + saline, CLP + immunoglobulin G (IgG) (250 mg/kg, iv), and CLP + immunoglobulins enriched with immunoglobulin M (IgGAM) (250 mg/kg, iv). Blood and brain samples were taken in two sets of experiments to see the early (24 h) and late (10 days) effects of treatment. Total complement activity, complement 3 (C3), and soluble complement C5b-9 levels were measured in the sera of rats using ELISA-based methods. Cerebral complement, complement receptor, NF-κB, Bax, and Bcl-2 expressions were analyzed by western blot and/or RT-PCR methods. Immune cell infiltration and gliosis were examined by immunohistochemistry using CD3, CD4, CD8, CD11b, CD19, and glial fibrillary acidic protein antibodies. Apoptotic neuronal death was investigated by TUNEL staining. Results IVIgG and IgGAM administration significantly reduced systemic complement activity and cerebral C5a and C5a receptor expression. Likewise, both treatment methods reduced proapoptotic NF-κB and Bax expressions in the brain. IVIgG and IgGAM treatment induced considerable amelioration in glial cell proliferation and neuronal apoptosis which were increased in non-treated septic rats. Conclusions We suggest that IVIgG and IgGAM administration ameliorates neuronal dysfunction and behavioral deficits by reducing apoptotic cell death and glial cell proliferation. In both treatment methods, these beneficial effects might be mediated through reduction of anaphylatoxic C5a activity and subsequent inhibition of inflammation and apoptosis pathways. Electronic supplementary material The online version of this article (doi:10.1186/s40635-016-0114-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Figen Esen
- Department of Anesthesiology, Istanbul Faculty of Medicine, Istanbul University, Capa-Fatih, 34039, Istanbul, Turkey
| | - Gunseli Orhun
- Department of Anesthesiology, Istanbul Faculty of Medicine, Istanbul University, Capa-Fatih, 34039, Istanbul, Turkey
| | - Perihan Ergin Ozcan
- Department of Anesthesiology, Istanbul Faculty of Medicine, Istanbul University, Capa-Fatih, 34039, Istanbul, Turkey.
| | - Evren Senturk
- Department of Anesthesiology, Istanbul Faculty of Medicine, Istanbul University, Capa-Fatih, 34039, Istanbul, Turkey
| | - Melike Kucukerden
- Neuroscience, Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Murat Giris
- Neuroscience, Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Ugur Akcan
- Neuroscience, Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Canan Ugur Yilmaz
- Department of Physiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Nurcan Orhan
- Neuroscience, Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Nadir Arican
- Department of Forensic Medicine, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Mehmet Kaya
- Department of Physiology, Istanbul Faculty of Medicine, Istanbul University, Istanbul, Turkey
| | - Sema Bilgic Gazioglu
- Immunology, Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Erdem Tuzun
- Neuroscience, Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey
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15
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Triantafilou M, Hughes TR, Morgan BP, Triantafilou K. Complementing the inflammasome. Immunology 2016; 147:152-64. [PMID: 26572245 DOI: 10.1111/imm.12556] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 11/03/2015] [Accepted: 11/06/2015] [Indexed: 01/02/2023] Open
Abstract
The innate immune system is an ancient surveillance system able to sense microbial invaders as well as aberrations in normal cell function. No longer viewed as a static and non-specific part of immunity, the innate immune system employs a plethora of specialized pattern recognition sensors to monitor and achieve homeostasis; these include the Toll-like receptors, the retinoic acid-inducible gene-like receptors, the nucleotide-binding oligomerization domain receptors (NLRs), the C-type lectins and the complement system. In order to increase specificity and diversity, innate immunity uses homotypic and heterotypic associations among these different components. Multi-molecular assemblies are formed both on the cell surface and in the cytosol to respond to pathogen and danger signals. Diverse, but tailored, responses to a changing environment are orchestrated depending on the the nature of the challenge and the repertoire of interacting receptors and components available in the sensing cell. It is now emerging that innate immunity operates a system of 'checks and balances' where interaction among the sensors is key in maintaining normal cell function. Complement sits at the heart of this alarm system and it is becoming apparent that it is capable of interacting with all the other pathways to effect a tailored immune response. In this review, we will focus on complement interactions with NLRs, the so-called 'inflammasomes', describing the molecular mechanisms that have been revealed so far and discussing the circumstantial evidence that exists for these interactions in disease states.
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Affiliation(s)
- Martha Triantafilou
- Institute of Infection and Immunity, School of Medicine, University Hospital of Wales, Cardiff University, Cardiff, UK
| | - Timothy R Hughes
- Institute of Infection and Immunity, School of Medicine, University Hospital of Wales, Cardiff University, Cardiff, UK
| | - Bryan Paul Morgan
- Institute of Infection and Immunity, School of Medicine, University Hospital of Wales, Cardiff University, Cardiff, UK
| | - Kathy Triantafilou
- Institute of Infection and Immunity, School of Medicine, University Hospital of Wales, Cardiff University, Cardiff, UK
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16
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Hawksworth OA, Coulthard LG, Taylor SM, Wolvetang EJ, Woodruff TM. Brief report: complement C5a promotes human embryonic stem cell pluripotency in the absence of FGF2. Stem Cells 2015; 32:3278-84. [PMID: 25132103 DOI: 10.1002/stem.1801] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 07/09/2014] [Indexed: 12/12/2022]
Abstract
The complement activation product, C5a, is a pivotal member of the innate immune response; however, a diverse number of nonimmune functions are now being ascribed to C5a signaling, including roles during embryonic development. Here, we identify the expression of the C5a precursor protein, C5, as well as the C5a receptors, C5aR and C5L2, in both human embryonic stem cells and human-induced pluripotent stem cells. We show that administration of a physiologically relevant dose of purified human C5a (1 nM) stimulates activation of ERK1/2 and AKT signaling pathways, and is able to promote maintenance of the pluripotent state in the absence of FGF2. C5a also reduced cell loss following dissociation of human pluripotent stem cells. Our results reveal that complement C5a signaling supports human stem cell pluripotency and survival, and thus may play a key role in shaping early human embryonic development.
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17
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Lian H, Zheng H. Signaling pathways regulating neuron-glia interaction and their implications in Alzheimer's disease. J Neurochem 2015; 136:475-91. [PMID: 26546579 DOI: 10.1111/jnc.13424] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 10/23/2015] [Accepted: 10/28/2015] [Indexed: 12/11/2022]
Abstract
Astrocytes are the most abundant cells in the central nervous system. They play critical roles in neuronal homeostasis through their physical properties and neuron-glia signaling pathways. Astrocytes become reactive in response to neuronal injury and this process, referred to as reactive astrogliosis, is a common feature accompanying neurodegenerative conditions, particularly Alzheimer's disease. Reactive astrogliosis represents a continuum of pathobiological processes and is associated with morphological, functional, and gene expression changes of varying degrees. There has been a substantial growth of knowledge regarding the signaling pathways regulating glial biology and pathophysiology in recent years. Here, we attempt to provide an unbiased review of some of the well-known players, namely calcium, proteoglycan, transforming growth factor β, NFκB, and complement, in mediating neuron-glia interaction under physiological conditions as well as in Alzheimer's disease. This review discusses the role of astrocytic NFκB and calcium as well as astroglial secreted factors, including proteoglycans, TGFβ, and complement in mediating neuronal function and AD pathogenesis through direct interaction with neurons and through cooperation with microglia.
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Affiliation(s)
- Hong Lian
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, USA
| | - Hui Zheng
- Huffington Center on Aging, Baylor College of Medicine, Houston, Texas, USA.,Institute of Neuroscience, Xiamen University College of Medicine, Xiamen, Fujian, China
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18
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Bajic G, Degn SE, Thiel S, Andersen GR. Complement activation, regulation, and molecular basis for complement-related diseases. EMBO J 2015; 34:2735-57. [PMID: 26489954 DOI: 10.15252/embj.201591881] [Citation(s) in RCA: 243] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 09/28/2015] [Indexed: 01/13/2023] Open
Abstract
The complement system is an essential element of the innate immune response that becomes activated upon recognition of molecular patterns associated with microorganisms, abnormal host cells, and modified molecules in the extracellular environment. The resulting proteolytic cascade tags the complement activator for elimination and elicits a pro-inflammatory response leading to recruitment and activation of immune cells from both the innate and adaptive branches of the immune system. Through these activities, complement functions in the first line of defense against pathogens but also contributes significantly to the maintenance of homeostasis and prevention of autoimmunity. Activation of complement and the subsequent biological responses occur primarily in the extracellular environment. However, recent studies have demonstrated autocrine signaling by complement activation in intracellular vesicles, while the presence of a cytoplasmic receptor serves to detect complement-opsonized intracellular pathogens. Furthermore, breakthroughs in both functional and structural studies now make it possible to describe many of the intricate molecular mechanisms underlying complement activation and the subsequent downstream events, as well as its cross talk with, for example, signaling pathways, the coagulation system, and adaptive immunity. We present an integrated and updated view of complement based on structural and functional data and describe the new roles attributed to complement. Finally, we discuss how the structural and mechanistic understanding of the complement system rationalizes the genetic defects conferring uncontrolled activation or other undesirable effects of complement.
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Affiliation(s)
- Goran Bajic
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
| | - Søren E Degn
- Department of Biomedicine, Aarhus University, Aarhus, Denmark Program in Cellular and Molecular Medicine, Children's Hospital, Boston, MA, USA
| | - Steffen Thiel
- Department of Biomedicine, Aarhus University, Aarhus, Denmark
| | - Gregers R Andersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark
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19
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Mahajan SD, Parikh NU, Woodruff TM, Jarvis JN, Lopez M, Hennon T, Cunningham P, Quigg RJ, Schwartz SA, Alexander JJ. C5a alters blood-brain barrier integrity in a human in vitro model of systemic lupus erythematosus. Immunology 2015; 146:130-43. [PMID: 26059553 DOI: 10.1111/imm.12489] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2015] [Revised: 05/27/2015] [Accepted: 06/01/2015] [Indexed: 12/23/2022] Open
Abstract
The blood-brain barrier (BBB) plays a crucial role in brain homeostasis, thereby maintaining the brain environment precise for optimal neuronal function. Its dysfunction is an intriguing complication of systemic lupus erythematosus (SLE). SLE is a systemic autoimmune disorder where neurological complications occur in 5-50% of cases and is associated with impaired BBB integrity. Complement activation occurs in SLE and is an important part of the clinical profile. Our earlier studies demonstrated that C5a generated by complement activation caused the loss of brain endothelial layer integrity in rodents. The goal of the current study was to determine the translational potential of these studies to a human system. To assess this, we used a two dimensional in vitro BBB model constructed using primary human brain microvascular endothelial cells and astroglial cells, which closely emulates the in vivo BBB allowing the assessment of BBB integrity. Increased permeability monitored by changes in transendothelial electrical resistance and cytoskeletal remodelling caused by actin fiber rearrangement were observed when the cells were exposed to lupus serum and C5a, similar to the observations in mice. In addition, our data show that C5a/C5aR1 signalling alters nuclear factor-κB translocation into nucleus and regulates the expression of the tight junction proteins, claudin-5 and zonula occludens 1 in this setting. Our results demonstrate for the first time that C5a regulates BBB integrity in a neuroinflammatory setting where it affects both endothelial and astroglial cells. In addition, we also demonstrate that our previous findings in a mouse model, were emulated in human cells in vitro, bringing the studies one step closer to understanding the translational potential of C5a/C5aR1 blockade as a promising therapeutic strategy in SLE and other neurodegenerative diseases.
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Affiliation(s)
| | - Neil U Parikh
- Department of Medicine, University at Buffalo, Buffalo, NY, USA
| | - Trent M Woodruff
- School of Biomedical Sciences, University of Queensland, St. Lucia, QLD, Australia
| | - James N Jarvis
- Department of Pediatrics, University at Buffalo, Buffalo, NY, USA
| | - Molly Lopez
- Department of Pediatrics, University at Buffalo, Buffalo, NY, USA
| | - Teresa Hennon
- Department of Medicine, University at Buffalo, Buffalo, NY, USA
| | | | - Richard J Quigg
- Department of Medicine, University at Buffalo, Buffalo, NY, USA
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20
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Coulthard LG, Woodruff TM. Is the complement activation product C3a a proinflammatory molecule? Re-evaluating the evidence and the myth. THE JOURNAL OF IMMUNOLOGY 2015; 194:3542-8. [PMID: 25848071 DOI: 10.4049/jimmunol.1403068] [Citation(s) in RCA: 188] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The complement activation product C3a is often described as a proinflammatory mediator, alongside its downstream cousin, C5a. However, emerging studies show that C3a has several anti-inflammatory facets in vivo. For example, in the acute inflammatory response, C3a acts in direct opposition to C5a, through preventing the accumulation of neutrophils in inflamed tissues by independently regulating their mobilization. This acute, protective, and opposing activity of C3a to C5a is also illustrated in models of septicemia. In this article, we reinvestigate the discovery and original classification of C3a as a proinflammatory mediator and highlight the emerging studies demonstrating anti-inflammatory effects for C3a in the immune response. It is our hope that this review illuminates these apparently contradictory roles for C3a and challenges the general dogma surrounding C3a, which, historically, has ubiquitously been described as a proinflammatory mediator. In light of this, we urge investigators to use "inflammatory modulator" as the descriptor for C3a.
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Affiliation(s)
- Liam G Coulthard
- School of Biomedical Sciences, University of Queensland, St. Lucia 4072, Queensland, Australia
| | - Trent M Woodruff
- School of Biomedical Sciences, University of Queensland, St. Lucia 4072, Queensland, Australia
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21
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Merle NS, Church SE, Fremeaux-Bacchi V, Roumenina LT. Complement System Part I - Molecular Mechanisms of Activation and Regulation. Front Immunol 2015; 6:262. [PMID: 26082779 PMCID: PMC4451739 DOI: 10.3389/fimmu.2015.00262] [Citation(s) in RCA: 952] [Impact Index Per Article: 105.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 05/11/2015] [Indexed: 12/12/2022] Open
Abstract
Complement is a complex innate immune surveillance system, playing a key role in defense against pathogens and in host homeostasis. The complement system is initiated by conformational changes in recognition molecular complexes upon sensing danger signals. The subsequent cascade of enzymatic reactions is tightly regulated to assure that complement is activated only at specific locations requiring defense against pathogens, thus avoiding host tissue damage. Here, we discuss the recent advances describing the molecular and structural basis of activation and regulation of the complement pathways and their implication on physiology and pathology. This article will review the mechanisms of activation of alternative, classical, and lectin pathways, the formation of C3 and C5 convertases, the action of anaphylatoxins, and the membrane-attack-complex. We will also discuss the importance of structure-function relationships using the example of atypical hemolytic uremic syndrome. Lastly, we will discuss the development and benefits of therapies using complement inhibitors.
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Affiliation(s)
- Nicolas S Merle
- UMR_S 1138, Cordeliers Research Center, Complement and Diseases Team, INSERM , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France
| | - Sarah Elizabeth Church
- UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France ; UMR_S 1138, Cordeliers Research Center, Integrative Cancer Immunology Team, INSERM , Paris , France
| | - Veronique Fremeaux-Bacchi
- UMR_S 1138, Cordeliers Research Center, Complement and Diseases Team, INSERM , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France ; Service d'Immunologie Biologique, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges-Pompidou , Paris , France
| | - Lubka T Roumenina
- UMR_S 1138, Cordeliers Research Center, Complement and Diseases Team, INSERM , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMR_S 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, Université Pierre et Marie Curie-Paris , Paris , France
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22
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Merle NS, Noe R, Halbwachs-Mecarelli L, Fremeaux-Bacchi V, Roumenina LT. Complement System Part II: Role in Immunity. Front Immunol 2015; 6:257. [PMID: 26074922 PMCID: PMC4443744 DOI: 10.3389/fimmu.2015.00257] [Citation(s) in RCA: 628] [Impact Index Per Article: 69.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Accepted: 05/09/2015] [Indexed: 12/14/2022] Open
Abstract
The complement system has been considered for a long time as a simple lytic cascade, aimed to kill bacteria infecting the host organism. Nowadays, this vision has changed and it is well accepted that complement is a complex innate immune surveillance system, playing a key role in host homeostasis, inflammation, and in the defense against pathogens. This review discusses recent advances in the understanding of the role of complement in physiology and pathology. It starts with a description of complement contribution to the normal physiology (homeostasis) of a healthy organism, including the silent clearance of apoptotic cells and maintenance of cell survival. In pathology, complement can be a friend or a foe. It acts as a friend in the defense against pathogens, by inducing opsonization and a direct killing by C5b–9 membrane attack complex and by triggering inflammatory responses with the anaphylatoxins C3a and C5a. Opsonization plays also a major role in the mounting of an adaptive immune response, involving antigen presenting cells, T-, and B-lymphocytes. Nevertheless, it can be also an enemy, when pathogens hijack complement regulators to protect themselves from the immune system. Inadequate complement activation becomes a disease cause, as in atypical hemolytic uremic syndrome, C3 glomerulopathies, and systemic lupus erythematosus. Age-related macular degeneration and cancer will be described as examples showing that complement contributes to a large variety of conditions, far exceeding the classical examples of diseases associated with complement deficiencies. Finally, we discuss complement as a therapeutic target.
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Affiliation(s)
- Nicolas S Merle
- UMRS 1138, Centre de Recherche des Cordeliers, INSERM , Paris , France ; UMRS 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMRS 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, UPMC Université Paris 06 , Paris , France
| | - Remi Noe
- UMRS 1138, Centre de Recherche des Cordeliers, INSERM , Paris , France ; UMRS 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMRS 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, UPMC Université Paris 06 , Paris , France ; Ecole Pratique des Hautes Études (EPHE) , Paris , France
| | - Lise Halbwachs-Mecarelli
- UMRS 1138, Centre de Recherche des Cordeliers, INSERM , Paris , France ; UMRS 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMRS 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, UPMC Université Paris 06 , Paris , France
| | - Veronique Fremeaux-Bacchi
- UMRS 1138, Centre de Recherche des Cordeliers, INSERM , Paris , France ; UMRS 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMRS 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, UPMC Université Paris 06 , Paris , France ; Service d'Immunologie Biologique, Assistance Publique-Hôpitaux de Paris, Hôpital Européen Georges-Pompidou , Paris , France
| | - Lubka T Roumenina
- UMRS 1138, Centre de Recherche des Cordeliers, INSERM , Paris , France ; UMRS 1138, Centre de Recherche des Cordeliers, Sorbonne Paris Cité, Université Paris Descartes , Paris , France ; UMRS 1138, Centre de Recherche des Cordeliers, Sorbonne Universités, UPMC Université Paris 06 , Paris , France
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23
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Shinjyo N, de Pablo Y, Pekny M, Pekna M. Complement Peptide C3a Promotes Astrocyte Survival in Response to Ischemic Stress. Mol Neurobiol 2015; 53:3076-3087. [DOI: 10.1007/s12035-015-9204-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 04/29/2015] [Indexed: 01/04/2023]
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24
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Lian H, Yang L, Cole A, Sun L, Chiang ACA, Fowler SW, Shim DJ, Rodriguez-Rivera J, Taglialatela G, Jankowsky JL, Lu HC, Zheng H. NFκB-activated astroglial release of complement C3 compromises neuronal morphology and function associated with Alzheimer's disease. Neuron 2014; 85:101-115. [PMID: 25533482 DOI: 10.1016/j.neuron.2014.11.018] [Citation(s) in RCA: 391] [Impact Index Per Article: 39.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/10/2014] [Indexed: 11/26/2022]
Abstract
Abnormal NFκB activation has been implicated in Alzheimer's disease (AD). However, the signaling pathways governing NFκB regulation and function in the brain are poorly understood. We identify complement protein C3 as an astroglial target of NFκB and show that C3 release acts through neuronal C3aR to disrupt dendritic morphology and network function. Exposure to Aβ activates astroglial NFκB and C3 release, consistent with the high levels of C3 expression in brain tissue from AD patients and APP transgenic mice, where C3aR antagonist treatment rescues cognitive impairment. Therefore, dysregulation of neuron-glia interaction through NFκB/C3/C3aR signaling may contribute to synaptic dysfunction in AD, and C3aR antagonists may be therapeutically beneficial.
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Affiliation(s)
- Hong Lian
- Huffington Center on Aging, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Houston, TX 77030, USA
| | - Li Yang
- Huffington Center on Aging, Houston, TX 77030, USA
| | - Allysa Cole
- Huffington Center on Aging, Houston, TX 77030, USA
| | - Lu Sun
- Huffington Center on Aging, Houston, TX 77030, USA
| | - Angie C-A Chiang
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Stephanie W Fowler
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - David J Shim
- Huffington Center on Aging, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Giulio Taglialatela
- Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Joanna L Jankowsky
- Huffington Center on Aging, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Hui-Chen Lu
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Department of Pediatrics, Baylor College of Medicine and the Cain Foundation Laboratories, Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA
| | - Hui Zheng
- Huffington Center on Aging, Houston, TX 77030, USA; Department of Molecular and Human Genetics, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA.
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25
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Neisseria meningitidis NalP cleaves human complement C3, facilitating degradation of C3b and survival in human serum. Proc Natl Acad Sci U S A 2013; 111:427-32. [PMID: 24367091 DOI: 10.1073/pnas.1321556111] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The complement system is a crucial component of the innate immune response against invading bacterial pathogens. The human pathogen Neisseria meningitidis (Nm) is known to possess several mechanisms to evade the complement system, including binding to complement inhibitors. In this study, we describe an additional mechanism used by Nm to evade the complement system and survive in human blood. Using an isogenic NalP deletion mutant and NalP complementing strains, we show that the autotransporter protease NalP cleaves C3, the central component of the complement cascade. The cleavage occurs 4 aa upstream from the natural C3 cleavage site and produces shorter C3a-like and longer C3b-like fragments. The C3b-like fragment is degraded in the presence of the complement regulators (factors H and I), and this degradation results in lower deposition of C3b on the bacterial surface. We conclude that NalP is an important factor to increase the survival of Nm in human serum.
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26
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Liu L, Zhang Y, Duan X, Peng Q, Liu Q, Zhou Y, Quan S, Xing G. C3a, C5a renal expression and their receptors are correlated to severity of IgA nephropathy. J Clin Immunol 2013; 34:224-32. [PMID: 24327134 DOI: 10.1007/s10875-013-9970-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2013] [Accepted: 11/11/2013] [Indexed: 10/25/2022]
Abstract
BACKGROUND IgA nephropathy (IgAN) is the most common primary kidney disease, often leading to chronic renal failure. Complement activation products C3a and C5a have broad pro-inflammatory potential through their receptors, C3aR and C5aR, and contribute to the pathogenesis of several inflammatory and autoimmune diseases, but their roles in IgAN are poorly defined. PURPOSE This study aimed to establish correlations between renal C3a, C5a, C3aR, C5aR, or serum/urinary C3a, C5a with clinical features and renal histopathology in patients with IgAN. METHODS Eighty-three patients with renal biopsy proven IgAN were investigated. Thirty patients fulfilled Haas's II, 30 fulfilled Haas's III and 23 fulfilled Haas's IV criteria. Deposition of C3a and C5a was assessed by immunohistochemistry. C3aR and C5aR mRNAs and proteins in kidney tissue were examined by real-time quantitative PCR (RT-qPCR) and immunohistochemical staining, respectively. C3a and C5a levels were quantified by ELISA in serum and urine samples of 30 IgAN patients, 10 control subjects and 10 septic patients. RESULTS Renal C3a and C5a deposition and C3aR and C5aR expression increased with increasing grades of renal pathology in IgAN patients. They positively correlated with proteinuria and serum creatinine (SCr), but not serum C-reactive protein (CRP) or complement 3 (C3). Serum C3a and C5a increased to levels comparable to septic patients but did not differ among IgAN sub-groups. In contrast, urinary C3a and C5a increased significantly and correlated positively with renal pathological grades. CONCLUSIONS In patients with IgAN, urinary and renal C3a and C5a and renal expression of C3aR and C5aR are significantly correlated with the activity and severity of renal injury. This observation warrants further study into the roles of C3a, C5a and their receptors in the pathogenesis of IgAN and as potential therapeutic targets.
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Affiliation(s)
- Lu Liu
- Department of Nephrology, First Affiliated Hospital of Zhengzhou University, Zhengzhou University Institute of Nephrology, Zhengzhou, 450052, China
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Gong B, Pan Y, Zhao W, Knable L, Vempati P, Begum S, Ho L, Wang J, Yemul S, Barnum S, Bilski A, Gong BY, Pasinetti GM. IVIG immunotherapy protects against synaptic dysfunction in Alzheimer's disease through complement anaphylatoxin C5a-mediated AMPA-CREB-C/EBP signaling pathway. Mol Immunol 2013; 56:619-29. [DOI: 10.1016/j.molimm.2013.06.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 06/21/2013] [Indexed: 01/05/2023]
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Klos A, Wende E, Wareham KJ, Monk PN. International Union of Basic and Clinical Pharmacology. [corrected]. LXXXVII. Complement peptide C5a, C4a, and C3a receptors. Pharmacol Rev 2013; 65:500-43. [PMID: 23383423 DOI: 10.1124/pr.111.005223] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The activation of the complement cascade, a cornerstone of the innate immune response, produces a number of small (74-77 amino acid) fragments, originally termed anaphylatoxins, that are potent chemoattractants and secretagogues that act on a wide variety of cell types. These fragments, C5a, C4a, and C3a, participate at all levels of the immune response and are also involved in other processes such as neural development and organ regeneration. Their primary function, however, is in inflammation, so they are important targets for the development of antiinflammatory therapies. Only three receptors for complement peptides have been found, but there are no satisfactory antagonists as yet, despite intensive investigation. In humans, there is a single receptor for C3a (C3a receptor), no known receptor for C4a, and two receptors for C5a (C5a₁ receptor and C5a₂ receptor). The most recently characterized receptor, the C5a₂ receptor (previously known as C5L2 or GPR77), has been regarded as a passive binding protein, but signaling activities are now ascribed to it, so we propose that it be formally identified as a receptor and be given a name to reflect this. Here, we describe the complex biology of the complement peptides, introduce a new suggested nomenclature, and review our current knowledge of receptor pharmacology.
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Affiliation(s)
- Andreas Klos
- Department for Medical Microbiology, Medical School Hannover, Hannover, Germany
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The role of complement component 3 (C3) in differentiation of myeloid-derived suppressor cells. Blood 2013; 121:1760-8. [PMID: 23299310 DOI: 10.1182/blood-2012-06-440214] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Myeloid-derived suppressor cells (MDSCs) play an important role in the regulation of the immune response. MDSC expansion occurs in many circumstances, including cancer, inflammation, stresses, and transplant tolerance. Liver transplants in mice are spontaneously accepted, but hepatocyte transplants are acutely rejected, suggesting the immunoregulatory activities of liver nonparenchymal cells. We have reported that hepatic stellate cells (HpSCs), the stromal cells in the liver, are immensely immunosuppressive and can effectively protect islet transplants via induction of MDSCs. The present study shows that the addition of HpSCs into dendritic cell (DC) culture promoted development of MDSCs, instead of DCs, which was highly dependent on complement component 3 (C3) from HpSCs. The C3(-/-) HpSCs lost their ability to induce MDSCs and, consequently, failed to protect the cotransplanted islet allografts. HpSCs produced complement activation factor B and factor D which then enhanced C3 cleavage to activation products iC3b and C3d. Addition of exogenous iC3b, but not C3d, into the DC culture led to the differentiation of MDSCs with potent immune-inhibitory function. These findings provide novel mechanistic insights into the differentiation of myeloid cells mediated by local tissue cells, and may assist in the development of MDSC-based therapy in clinical settings.
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Bajic G, Yatime L, Klos A, Andersen GR. Human C3a and C3a desArg anaphylatoxins have conserved structures, in contrast to C5a and C5a desArg. Protein Sci 2012. [PMID: 23184394 DOI: 10.1002/pro.2200] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Complement is a part of innate immunity that has a critical role in the protection against microbial infections, bridges the innate with the adaptive immunity and initiates inflammation. Activation of the complement, by specific recognition of molecular patterns presented by an activator, for example, a pathogen cell, in the classical and lectin pathways or spontaneously in the alternative pathway, leads to the opsonization of the activator and the production of pro-inflammatory molecules such as the C3a anaphylatoxin. The biological function of this anaphylatoxin is regulated by carboxypeptidase B, a plasma protease that cleaves off the C-terminal arginine yielding C3a desArg, an inactive form. While functional assays demonstrate strikingly different physiological effects between C3a and C3a desArg, no structural information is available on the possible conformational differences between the two proteins. Here, we report a novel and simple expression and purification protocol for recombinant human C3a and C3a desArg anaphylatoxins, as well as their crystal structures at 2.3 and 2.6 Å, respectively. Structural analysis revealed no significant conformational differences between the two anaphylatoxins in contrast to what has been reported for C5a and C5a desArg. We compare the structures of different anaphylatoxins and discuss the relevance of their observed conformations to complement activation and binding of the anaphylatoxins to their cognate receptors.
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Affiliation(s)
- Goran Bajic
- Department of Molecular Biology and Genetics, Aarhus University, Gustav Wieds Vej 10C, DK-8000 Aarhus, Denmark
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Schoengraf P, Lambris JD, Recknagel S, Kreja L, Liedert A, Brenner RE, Huber-Lang M, Ignatius A. Does complement play a role in bone development and regeneration? Immunobiology 2012; 218:1-9. [PMID: 22464814 DOI: 10.1016/j.imbio.2012.01.020] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 01/27/2012] [Accepted: 01/27/2012] [Indexed: 12/16/2022]
Abstract
The skeletal and the immune system are not two independent systems, rather, there are multifaceted and complex interactions between the different cell types of both systems and there are several shared cytokines. As a part of the innate immunity, the complement system was found to be an important link between bone and immunity. Complement proteins appear to be involved in bone development and homeostasis, and specifically influence osteoblast and osteoclast activity. This review describes the complex mutual regulation of the two systems, and indicates some of the negative side effects as a result of inappropriate or excessive complement activation.
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Affiliation(s)
- Philipp Schoengraf
- Institute of Orthopaedic Research and Biomechanics, Centre of Muskuloskelettal Research, University of Ulm, Helmholtzstrasse 14, 89081 Ulm, Germany
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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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Han G, Geng S, Li Y, Chen G, Wang R, Li X, Ma Y, Shen B, Li Y. γδT-cell function in sepsis is modulated by C5a receptor signalling. Immunology 2011; 133:340-9. [PMID: 21501163 DOI: 10.1111/j.1365-2567.2011.03445.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
We previously showed that γδT cells are involved in the pathogenesis of sepsis, but, the underlying mechanisms remained unclear. The present study demonstrates, for the first time, that γδT cells express the complement C5a receptor (C5aR, CD88) and that CD88 expression in γδT cells was up-regulated in mice following sepsis both at protein and mRNA levels. Complement C5a itself contributed to the regulation of C5aR expression on γδT cells, as (i) neutralization of C5a in vivo prevented the expression of C5aR on γδT cells in septic mice and (ii) incubation of mouse spleen cells or purified γδT cells with recombinant C5a in vitro increased CD88 expression by γδT cells at both protein and mRNA levels. C5a receptor on γδT cells also mediates increased interleukin-17 (IL-17) expression as incubation of mouse spleen cells or purified γδT cells with recombinant C5a promotes the IL-17 expression by γδT cells. Ligation of the C5aR on γδT cells activated the phosphoinositide 3-kinase (PI3K)/Akt signalling pathway, which enhances CD88 expression and promotes IL-17 secretion. These results demonstrate that C5a acts directly on the C5aR expressed on γδT cells, resulting in cell activation, and subsequently enhances their capacity for IL-17 production. The up-regulation of the PI3K/Akt pathway following C5a stimulation contributes to up-regulation of γδT-cell function.
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Affiliation(s)
- Gencheng Han
- Department of Molecular Immunology, Institute of Basic Medical Sciences, Beijing, China.
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CNS-specific expression of C3a and C5a exacerbate demyelination severity in the cuprizone model. Mol Immunol 2010; 48:219-30. [PMID: 20813409 DOI: 10.1016/j.molimm.2010.08.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Revised: 08/03/2010] [Accepted: 08/10/2010] [Indexed: 12/18/2022]
Abstract
Demyelination in the central nervous system (CNS) is known to involve several immune effector mechanisms, including complement proteins. Local production of complement by glial cells in the brain can be both harmful and protective. To investigate the roles of C3a and C5a in demyelination and remyelination pathology we utilized the cuprizone model. Transgenic mice expressing C3a or C5a under the control of the glial fibrillary acidic protein (GFAP) promoter had exacerbated demyelination and slightly delayed remyelination in the corpus callosum compared to WT mice. C3a and C5a transgenic mice had increased cellularity in the corpus callosum due to increase activation and/or migration of microglia. Oligodendrocytes migrated to the corpus callosum in higher numbers during early remyelination events in C3a and C5a transgenic mice, thus enabling these mice to remyelinate as effectively as WT mice by the end of the 10 week study. To determine the effects of C3a and/or C5a on individual glial subsets, we created murine recombinant C3a and C5a proteins. When microglia and mixed glial cultures were stimulated with C3a and/or C5a, we observed an increase in the production of proinflammatory cytokines and chemokines. In contrast, astrocytes had decreased cytokine and chemokine production in the presence of C3a and/or C5a. We also found that the MAPK pathway proteins JNK and ERK1/2 were activated in glia upon stimulation with C3a and C5a. Overall, our findings show that although C3a and C5a production in the brain play a negative role during demyelination, these proteins may aid in remyelination.
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Jacob A, Hack B, Chiang E, Garcia JGN, Quigg RJ, Alexander JJ. C5a alters blood-brain barrier integrity in experimental lupus. FASEB J 2010; 24:1682-8. [PMID: 20065106 DOI: 10.1096/fj.09-138834] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The blood-brain barrier (BBB) is a crucial anatomic location in the brain. Its dysfunction complicates many neurodegenerative diseases, from acute conditions, such as sepsis, to chronic diseases, such as systemic lupus erythematosus (SLE). Several studies suggest an altered BBB in lupus, but the underlying mechanism remains unknown. In the current study, we observed a definite loss of BBB integrity in MRL/MpJ-Tnfrsf6(lpr) (MRL/lpr) lupus mice by IgG infiltration into brain parenchyma. In line with this result, we examined the role of complement activation, a key event in this setting, in maintenance of BBB integrity. Complement activation generates C5a, a molecule with multiple functions. Because the expression of the C5a receptor (C5aR) is significantly increased in brain endothelial cells treated with lupus serum, the study focused on the role of C5a signaling through its G-protein-coupled receptor C5aR in brain endothelial cells, in a lupus setting. Reactive oxygen species production increased significantly in endothelial cells, in both primary cells and the bEnd3 cell line treated with lupus serum from MRL/lpr mice, compared with those treated with control serum from MRL(+/+) mice. In addition, increased permeability monitored by changes in transendothelial electrical resistance, cytoskeletal remodeling caused by actin fiber rearrangement, and increased iNOS mRNA expression were observed in bEnd3 cells. These disruptive effects were alleviated by pretreating cells with a C5a receptor antagonist (C5aRant) or a C5a antibody. Furthermore, the structural integrity of the vasculature in MRL/lpr brain was maintained by C5aR inhibition. These results demonstrate the regulation of BBB integrity by the complement system in a neuroinflammatory setting. For the first time, a novel role of C5a in the maintenance of BBB integrity is identified and the potential of C5a/C5aR blockade highlighted as a promising therapeutic strategy in SLE and other neurodegenerative diseases.
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Affiliation(s)
- Alexander Jacob
- Department of Medicine, University of Chicago, Chicago, IL 60637, USA
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Peng Q, Li K, Wang N, Li Q, Asgari E, Lu B, Woodruff TM, Sacks SH, Zhou W. Dendritic cell function in allostimulation is modulated by C5aR signaling. THE JOURNAL OF IMMUNOLOGY 2009; 183:6058-68. [PMID: 19864610 DOI: 10.4049/jimmunol.0804186] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Regulation of T cell immunity by C5a has been suggested from recent studies. However, the underlying mechanisms, particularly the involved cells and biochemical basis, are not well defined. In this study, the direct modulation of dendritic cell (DC) activation and its function in T cell stimulation by C5a-C5aR interaction and the involved signaling pathways were investigated. We show that DCs from C5aR(-/-) mice and normal DCs treated with C5aR antagonist have less-activated phenotype characterized with increased IL-10 and decreased IL-12p70 production in response to LPS stimulation, lowered surface expression of MHC class II, B7.2, and consequently have reduced capacity to stimulate allospecific T cells. Conversely, C5a stimulation up-regulates DC activation and its function in allostimulation. Furthermore, stimulation of C5aR mediates the inhibition of cAMP production and protein kinase A activity and is involved in activation of PI3K/AKT and NF-kappaB signaling in DCs. These results demonstrate that C5a acts directly on C5aR expressed on DCs resulting in the cell activation and subsequently enhances its capacity for allospecific T cell stimulation. It also suggests that NF-kappaB signaling induced by down-regulation of cAMP/ protein kinase A pathway and up-regulation of PI3K/AKT pathway following C5a stimulation may contribute to up-regulation of DC function.
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Affiliation(s)
- Qi Peng
- Complement Laboratory, MRC Centre for Transplantation, King's College London, School of Medicine at Guy's Hospital, London, UK
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Shinjyo N, Ståhlberg A, Dragunow M, Pekny M, Pekna M. Complement-Derived Anaphylatoxin C3a Regulates In Vitro Differentiation and Migration of Neural Progenitor Cells. Stem Cells 2009; 27:2824-32. [DOI: 10.1002/stem.225] [Citation(s) in RCA: 127] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Klos A, Tenner AJ, Johswich KO, Ager RR, Reis ES, Köhl J. The role of the anaphylatoxins in health and disease. Mol Immunol 2009; 46:2753-66. [PMID: 19477527 DOI: 10.1016/j.molimm.2009.04.027] [Citation(s) in RCA: 484] [Impact Index Per Article: 32.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2009] [Accepted: 04/28/2009] [Indexed: 12/16/2022]
Abstract
The anaphylatoxin (AT) C3a, C5a and C5a-desArg are generally considered pro-inflammatory polypeptides generated after proteolytic cleavage of C3 and C5 in response to complement activation. Their well-appreciated effector functions include chemotaxis and activation of granulocytes, mast cells and macrophages. Recent evidence suggests that ATs are also generated locally within tissues by pathogen-, cell-, or contact system-derived proteases. This local generation of ATs is important for their pleiotropic biologic effects beyond inflammation. The ATs exert most of the biologic activities through ligation of three cognate receptors, i.e. the C3a receptor, the C5a receptor and the C5a receptor-like, C5L2. Here, we will discuss recent findings suggesting that ATs regulate cell apoptosis, lipid metabolism as well as innate and adaptive immune responses through their impact on antigen-presenting cells and T cells. As we will outline, such regulatory functions of ATs and their receptors play important roles in the pathogenesis of allergy, autoimmunity, neurodegenerative diseases, cancer and infections with intracellular pathogens.
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Affiliation(s)
- Andreas Klos
- Institute of Medical Microbiology and Hospital Epidemiology, Medical School Hannover, MHH, Germany
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Wenderfer SE, Wang H, Ke B, Wetsel RA, Braun MC. C3a receptor deficiency accelerates the onset of renal injury in the MRL/lpr mouse. Mol Immunol 2009; 46:1397-404. [PMID: 19167760 DOI: 10.1016/j.molimm.2008.12.004] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2008] [Revised: 12/04/2008] [Accepted: 12/07/2008] [Indexed: 12/23/2022]
Abstract
The development and progression of systemic lupus erythematosus (SLE) is strongly associated with complement activation and deposition. The anaphylatoxin C3a is a product of complement activation with immunomodulatory properties, and the receptor for C3a (C3aR) is not only expressed by granulocytes and antigen presenting cell populations, but it is also strongly up-regulated in lupus prone mice with active nephritis. In order to characterize the role of the C3aR in inflammatory nephritis, we bred C3aR knock out mice onto the MRL/lpr genetic background (C3aR KO MRL). Compared to control MRL/lpr mice, C3aR KO MRL mice had elevated auto-antibody titers and an earlier onset of renal injury. At 8 weeks, renal expression of a wide range of chemokines and chemokine receptors was increased in C3aR KO MRL kidneys compared to controls. Only the expression of MCP-1 was significantly decreased in the C3aR KO MRL mice. The increased chemokine and chemokine receptor expression seen in the C3aR KO MRL mice was associated with a more rapid rise in serum creatinine and the acceleration of renal fibrosis. However, loss of the C3aR had little impact on long-term kidney injury and did not alter survival. These findings suggest that activation of the C3aR plays a protective, not pathologic, role in the early phase of inflammatory nephritis in the MRL/lpr model of SLE.
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Affiliation(s)
- Scott E Wenderfer
- The Center for Immunology and Autoimmune Diseases, Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, University of Texas Health Science Center-Houston, Houston, TX 77030, USA
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Cyclic AMP plays a critical role in C3a-receptor-mediated regulation of dendritic cells in antigen uptake and T-cell stimulation. Blood 2008; 112:5084-94. [PMID: 18812470 DOI: 10.1182/blood-2008-05-156646] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The biochemical basis for complement acting directly on antigen-presenting cells to enhance their function in T-cell stimulation has been unclear. Here we present evidence that engagement of C3a receptor (C3aR) on the surface of dendritic cells (DCs) leads to alterations in the level of intracellular cyclic adenosine monophosphate (cAMP), a potent negative regulator of inflammatory cytokines. C3aR activation-induced depression of cAMP was associated with enhanced capacity of DCs for antigen uptake and T-cell stimulation. Conversely, C3aR-deficient DCs showed elevation of cAMP and impaired properties for antigen uptake and immune stimulation. Similarities in the phenotype of C3-deficient and C3aR-deficient DCs suggest that local production of C3 with extracellular metabolism to C3a is an important driver of DC alterations in cAMP. The finding of a link between complement and adaptive immune stimulation through cAMP offers new insight into how innate and adaptive immunity combine to generate efficient effector and memory responses.
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Bogestål YR, Barnum SR, Smith PLP, Mattisson V, Pekny M, Pekna M. Signaling through C5aR is not involved in basal neurogenesis. J Neurosci Res 2008; 85:2892-7. [PMID: 17551982 DOI: 10.1002/jnr.21401] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The complement system, an important part of the innate immune system, provides protection against invading pathogens, in part through its proinflammatory activities. Although most complement proteins are synthesized locally in the brain and the relevant complement receptors are expressed on resident brain cells, little is known about brain-specific role(s) of the complement system. C3a and C5a, complement-derived peptides with anaphylatoxic properties, have been implicated in noninflammatory functions, such as tissue regeneration and neuroprotection. Recently, we have shown that signaling through C3a receptor (C3aR) is involved in the regulation of neurogenesis. In the present study, we assessed basal neurogenesis in mice lacking C5a receptor (C5aR(-/-)) and mice expressing C3a and C5a, respectively in the CNS under the control of glial fibrillary acidic protein (GFAP) promoter (C3a/GFAP and C5a/GFAP, respectively) and thus without the requirement for complement activation. We did not observe any difference among C5aR(-/-), C3a/GFAP and C5a/GFAP mice and their respective controls in the number of newly formed neuroblasts and newly formed neurons in the subventricular zone (SVZ) of lateral ventricles and hippocampal dentate gyrus, the two neurogenic niches in the adult brain, or the olfactory bulb, the final destination of new neurons formed in the SVZ. Our results indicate that signaling through C5aR is not involved in basal neurogenesis in adult mice and that basal neurogenesis in adult C3a/GFAP and C5a/GFAP mice is not altered.
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Affiliation(s)
- Yalda Rahpeymai Bogestål
- Department of Medical Chemistry and Cell Biology, Institute of Biomedicine, Sahlgrenska Academy at Göteborg University, Göteborg, Sweden
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Yao EH, Fukuda N, Ueno T, Tsunemi A, Endo M, Matsumoto K. Complement 3 activates the KLF5 gene in rat vascular smooth muscle cells. Biochem Biophys Res Commun 2008; 367:468-73. [PMID: 18178156 DOI: 10.1016/j.bbrc.2007.12.160] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2007] [Accepted: 12/22/2007] [Indexed: 11/30/2022]
Abstract
We have shown that spontaneously hypertensive rat (SHR)-derived vascular smooth muscle cells (VSMCs) change to the synthetic phenotype and show increased expression of complement 3 (C3) and that C3 plays a role in the change to the synthetic phenotype. To determine the mechanisms underlying the effects of C3 on this phenotypic change, we examined the effects of C3a on transcription factors involved in VSMC phenotype and found that C3a increased the expression of Krüppel-like zinc-finger transcription factor 5 (KLF5) mRNA. C3a increased KLF5 promoter activity in a concentration-dependent manner. Deletion analysis of the promoter region of the KLF5 gene revealed that the region between nucleotides-991 and -699 contains the transcriptional regulatory element stimulated by C3a. C3a induced extracellular signal-regulated kinase (ERK) phosphorylation, and C3a-increased KLF5 promoter activity was completely inhibited by the MEK inhibitor U0126. These findings suggest that C3 increases KLF5 promoter activity and gene expression via ERK signaling.
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Affiliation(s)
- En-Hui Yao
- Division of Nephrology, Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Ooyaguchi-kami 30-1, Itabashi-ku, Tokyo 173-8610, Japan
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Johswich K, Klos A. C5L2--an anti-inflammatory molecule or a receptor for acylation stimulating protein (C3a-desArg)? ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 598:159-80. [PMID: 17892211 DOI: 10.1007/978-0-387-71767-8_12] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Kay Johswich
- Medical School Hannover, Department of Medical Microbiology, 30625 Hannover, Germany.
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Dillard P, Wetsel RA, Drouin SM. Complement C3a regulates Muc5ac expression by airway Clara cells independently of Th2 responses. Am J Respir Crit Care Med 2007; 175:1250-8. [PMID: 17400733 PMCID: PMC2176092 DOI: 10.1164/rccm.200701-049oc] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
RATIONALE The factors that control the secretion of epithelial mucins are essential to understanding obstructive airway diseases such as asthma. Although the complement anaphylatoxin C3a and its receptor have been shown to promote many features of allergic lung inflammation, the contribution to mucin expression has not been elucidated. OBJECTIVES To determine if the C3a receptor with its ligand regulates airway epithelial mucin production. METHODS Mice deficient in the C3a receptor were examined in a model of allergic airway disease for the presence of goblet cells and the gel-forming secreted mucin Muc5ac. MEASUREMENTS AND MAIN RESULTS Lungs from antigen-challenged C3a receptor-deficient mice revealed a dramatic decrease in goblet cells and Muc5ac compared with challenged wild-type control animals. These differences were dependent on C3a binding to its receptor since intranasal challenge with C3a induced the formation of goblet cells only in wild-type but not C3a receptor-deficient mice. Increased numbers of goblet cells were also found in C3a-stimulated RAG-1-deficient mice demonstrating a mechanism independent of T lymphocytes and Th2 cytokines, mediators which have been shown to regulate mucin expression. A direct physiological role for C3a in these models was further demonstrated in cultures of airway epithelial Clara cells, which not only express the C3a receptor but also produce Muc5ac in response to C3a. CONCLUSIONS These studies identify a novel C3a receptor-dependent mechanism in the development of airway epithelial goblet cells and regulation of Muc5ac production and implicate C3a as a mediator of airway obstruction in asthma.
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Affiliation(s)
- Patricia Dillard
- The Brown Foundation Institute of Molecular Medicine for the Prevention of Human Diseases, The University of Texas Health Science Center at Houston, 1825 Pressler Street, Houston, TX 77030, USA
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Martin CB, Martin BK. Characterization of the Murine C3a Receptor Enhancer-Promoter: Expression Control by an Activator Protein 1 Sequence and an Ets-Like Site. THE JOURNAL OF IMMUNOLOGY 2005; 175:3123-32. [PMID: 16116202 DOI: 10.4049/jimmunol.175.5.3123] [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
The complement anaphylatoxins, C3a and C5a, exert their effects by binding to their respective receptors. A number of studies have implicated these proteins in human disease, yet little is known about anaphylatoxin receptor gene regulation. In this report, we demonstrate that most of the regulatory functions in the murine C3aR gene lie within 50 bp of the transcription start site. This region is critical for macrophage expression but does not have activity in a non-expressing melanoma cell line. Within this small region are putative consensus binding sites for AP-1, NF-kappaB, Ets, and GATA transcription factors. Lack of a corresponding NF-kappaB site in the human sequence and lack of DNA binding activity in macrophage nuclear extracts suggests that the NF-kappaB site is nonfunctional. Luciferase data demonstrate that the GATA site functions as a negative regulatory element in RAW 264.7 macrophages. The AP-1 and Ets sites are critical for C3aR reporter gene expression, such that when each is mutated, a significant loss of activity is observed. Furthermore, we demonstrate that these sequences cooperate to mediate both basal and LPS-induced expression of C3aR. Interestingly, EMSA analyses demonstrate that the AP-1 site binds to c-Jun, and in vivo footprinting shows a typical footprint in this site, but the Ets site does not have a "typical" Ets footprint and does not bind to Ets-1/2 proteins in RAW 264.7 extracts. These data suggest that, although the control region for C3aR is small, interaction of several transcription factors can lead to complex patterns of gene regulation.
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Affiliation(s)
- Carol B Martin
- Department of Microbiology, University of Iowa, Iowa City 52242, USA
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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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Twining CM, Sloane EM, Schoeniger DK, Milligan ED, Martin D, Marsh H, Maier SF, Watkins LR. Activation of the spinal cord complement cascade might contribute to mechanical allodynia induced by three animal models of spinal sensitization. THE JOURNAL OF PAIN 2005; 6:174-83. [PMID: 15772911 DOI: 10.1016/j.jpain.2004.11.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The present series of experiments examined whether the complement cascade might play a key role in the expression of mechanical allodynia. Soluble complement receptor 1 (sCR1) was used to block the activation of the membrane attack pathway of the complement cascade. In doing so, sCR1 prevents the formation of the biologically active end products C3a, C5a, and membrane attack complexes (MACs). Intrathecal sCR1 had no effect on the behavioral responses of control groups. In contrast, blockade of this pathway abolished the expression of mechanical allodynia induced by peripheral nerve inflammation (sciatic inflammatory neuropathy model), partial sciatic nerve injury (chronic constriction injury model), and intrathecal injection of human immunodeficiency virus type 1 gp120, a viral envelope protein that activates glia. The fact that enhanced nociception was prevented or reversed in all 3 paradigms suggests that complement might be broadly involved in spinally mediated pain enhancement. The mechanisms whereby complement activation might potentially affect the functioning of microglia, astrocytes, and neurons are discussed. The complement cascade has not been previously implicated in spinal sensitization. These data suggest that complement activation within the spinal cord might contribute to enhanced pain states and provide additional evidence for immune regulation of pain transmission.
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Affiliation(s)
- Carin M Twining
- Department of Psychology and the Center of Neuroscience, University of Colorado at Boulder, 80309, USA
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Boos L, Campbell IL, Ames R, Wetsel RA, Barnum SR. Deletion of the complement anaphylatoxin C3a receptor attenuates, whereas ectopic expression of C3a in the brain exacerbates, experimental autoimmune encephalomyelitis. THE JOURNAL OF IMMUNOLOGY 2004; 173:4708-14. [PMID: 15383607 DOI: 10.4049/jimmunol.173.7.4708] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The C3aR is expressed throughout the CNS and is increased in expression on glial cells during CNS inflammation. However, the role that C3a and the C3aR play in chronic inflammation, such as in the demyelinating disease experimental autoimmune encephalomyelitis (EAE), remains unclear. We show in this study that deletion of the C3aR is protective in myelin oligodendrocyte glycoprotein-induced EAE in C57BL/6 mice. C3aR-deficient (C3aR(-/-)) mice had a significantly attenuated course of EAE compared with control mice during the chronic phase of the disease. Immunohistochemical analysis demonstrated modestly reduced macrophage and T cell infiltration in the spinal cords of C3aR(-/-) mice. To examine the role of C3a in EAE, we developed a transgenic mouse that expresses C3a exclusively in the CNS using the glial fibrillary acidic protein (GFAP) promoter. We observed that C3a/GFAP mice had exacerbated EAE during the chronic phase of the disease, with significant mortality compared with nontransgenic littermates. C3a/GFAP mice had massive meningeal and perivascular infiltration of macrophages and CD4(+) T cells. These studies indicate that C3a may contribute to the pathogenesis of demyelinating disease by directly or indirectly chemoattracting encephalitogenic cells to the CNS.
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MESH Headings
- Animals
- Brain/immunology
- Brain/metabolism
- Cell Movement/genetics
- Cell Movement/immunology
- Cells, Cultured
- Complement C3a/biosynthesis
- Complement C3a/genetics
- Complement C3a/metabolism
- Encephalomyelitis, Autoimmune, Experimental/genetics
- Encephalomyelitis, Autoimmune, Experimental/immunology
- Encephalomyelitis, Autoimmune, Experimental/pathology
- Encephalomyelitis, Autoimmune, Experimental/prevention & control
- Gene Deletion
- Glial Fibrillary Acidic Protein/genetics
- Glycoproteins/administration & dosage
- Humans
- Membrane Proteins/biosynthesis
- Membrane Proteins/deficiency
- Membrane Proteins/genetics
- Membrane Proteins/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Myelin Sheath/pathology
- Myelin-Oligodendrocyte Glycoprotein
- Peptide Fragments/administration & dosage
- Receptors, Complement/biosynthesis
- Receptors, Complement/deficiency
- Receptors, Complement/genetics
- Receptors, Complement/physiology
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Affiliation(s)
- Laura Boos
- Department of Microbiology, University of Alabama, Birmingham, AL 35294, USA
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