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Wang Y, Liu W, Xu Y, He X, Yuan Q, Luo P, Fan W, Zhu J, Zhang X, Cheng X, Jiang Y, Xu HE, Zhuang Y. Revealing the signaling of complement receptors C3aR and C5aR1 by anaphylatoxins. Nat Chem Biol 2023; 19:1351-1360. [PMID: 37169960 DOI: 10.1038/s41589-023-01339-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 04/14/2023] [Indexed: 05/13/2023]
Abstract
The complement receptors C3aR and C5aR1, whose signaling is selectively activated by anaphylatoxins C3a and C5a, are important regulators of both innate and adaptive immune responses. Dysregulations of C3aR and C5aR1 signaling lead to multiple inflammatory disorders, including sepsis, asthma and acute respiratory distress syndrome. The mechanism underlying endogenous anaphylatoxin recognition and activation of C3aR and C5aR1 remains elusive. Here we reported the structures of C3a-bound C3aR and C5a-bound C5aR1 as well as an apo-C3aR structure. These structures, combined with mutagenesis analysis, reveal a conserved recognition pattern of anaphylatoxins to the complement receptors that is different from chemokine receptors, unique pocket topologies of C3aR and C5aR1 that mediate ligand selectivity, and a common mechanism of receptor activation. These results provide crucial insights into the molecular understanding of C3aR and C5aR1 signaling and structural templates for rational drug design for treating inflammation disorders.
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Affiliation(s)
- Yue Wang
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Weiyi Liu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Youwei Xu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xinheng He
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qingning Yuan
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Ping Luo
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Wenjia Fan
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing, China
| | - Jingpeng Zhu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xinyue Zhang
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Xi Cheng
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yi Jiang
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
- Lingang Laboratory, Shanghai, China
| | - H Eric Xu
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
- University of Chinese Academy of Sciences, Beijing, China.
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
| | - Youwen Zhuang
- State Key Laboratory of Drug Research, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
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2
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Schanzenbacher J, Hendrika Kähler K, Mesler E, Kleingarn M, Marcel Karsten C, Leonard Seiler D. The role of C5a receptors in autoimmunity. Immunobiology 2023; 228:152413. [PMID: 37598588 DOI: 10.1016/j.imbio.2023.152413] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 06/04/2023] [Accepted: 06/10/2023] [Indexed: 08/22/2023]
Abstract
The complement system is an essential component of the innate immune response and plays a vital role in host defense and inflammation. Dysregulation of the complement system, particularly involving the anaphylatoxin C5a and its receptors (C5aR1 and C5aR2), has been linked to several autoimmune diseases, indicating the potential for targeted therapies. C5aR1 and C5aR2 are seven-transmembrane receptors with distinct signaling mechanisms that play both partially overlapping and opposing roles in immunity. Both receptors are expressed on a broad spectrum of immune and non-immune cells and are involved in cellular functions and physiological processes during homeostasis and inflammation. Dysregulated C5a-mediated inflammation contributes to autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, epidermolysis bullosa acquisita, antiphospholipid syndrome, and others. Therefore, targeting C5a or its receptors may yield therapeutic innovations in these autoimmune diseases by reducing the recruitment and activation of immune cells that lead to tissue inflammation and injury, thereby exacerbating the autoimmune response. Clinical trials focused on the inhibition of C5 cleavage or the C5a/C5aR1-axis using small molecules or monoclonal antibodies hold promise for bringing novel treatments for autoimmune diseases into practice. However, given the heterogeneous nature of (systemic) autoimmune diseases, there are still several challenges, such as patient selection, optimal dosing, and treatment duration, that require further investigation and development to realize the full therapeutic potential of C5a receptor inhibition, ideally in the context of a personalized medicine approach. Here, we aim to provide a brief overview of the current knowledge on the function of C5a receptors, the involvement of C5a receptors in autoimmune disorders, the molecular mechanisms underlying C5a receptor-mediated autoimmunity, and the potential for targeted therapies to modulate their activity.
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Affiliation(s)
- Jovan Schanzenbacher
- Institute for Systemic Inflammation Research (ISEF), University of Lübeck, Lübeck, Germany
| | - Katja Hendrika Kähler
- Institute for Systemic Inflammation Research (ISEF), University of Lübeck, Lübeck, Germany
| | - Evelyn Mesler
- Institute for Systemic Inflammation Research (ISEF), University of Lübeck, Lübeck, Germany
| | - Marie Kleingarn
- Institute for Systemic Inflammation Research (ISEF), University of Lübeck, Lübeck, Germany
| | | | - Daniel Leonard Seiler
- Institute for Systemic Inflammation Research (ISEF), University of Lübeck, Lübeck, Germany.
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3
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Zhu Y, Wang X, Xu Y, Chen L, Ding P, Chen J, Hu W. An Integrated Analysis of C5AR2 Related to Malignant Properties and Immune Infiltration of Breast Cancer. Front Oncol 2021; 11:736725. [PMID: 34595119 PMCID: PMC8476960 DOI: 10.3389/fonc.2021.736725] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 08/27/2021] [Indexed: 12/13/2022] Open
Abstract
Background C5AR2 (GPR77, C5L2) is the second receptor for C5a that is a potent protein generated by complement activation. C5AR2 can mediate its own signaling events and exert significant immunomodulatory effects through those events. However, research of C5AR2 in cancer is limited, and its function remains unclear in breast cancer. Methods The expression of C5AR2 and its correlations with prognosis, immune infiltration, tumor mutation burden (TMB), and microsatellite instability (MSI) in more than thirty types of cancers were described through GTEx, TCGA, PrognoScan, TIMER2.0, CCLE, HPA, and TISIDB database. C5AR2 showed strong relationships to those immune marker sets in breast cancer. Otherwise, CCK8 assay and Transwell assay were conducted to illustrate the role of C5AR2 in migration, invasion, and proliferation of breast cancer cells. Results Generally, C5AR2 expression differed across most cancerous and noncancerous tissues, and high C5AR2 expression significantly related to poor prognosis in BRCA, GBM, KICH, LAML, LGG, LIHC, PAAD, and STAD. Moreover, C5AR2 expression levels were dramatically correlated with recognized immune infiltration, especially the polarization of macrophages in breast cancer. Gene set enrichment analysis confirmed that C5AR2 participates in regulating multiple signaling pathways involved in tumorigenesis as well as tumor immunity. C5AR2 overexpression facilitated the functions such as migration, invasion, and proliferation in breast cancer cells, which is consistent with bioinformatics analysis. Conclusions C5AR2 is involved in immune infiltration and malignant characteristics of breast cancer, which may be a prospective biomarker for breast cancer.
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Affiliation(s)
- Yumeng Zhu
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Xiaochao Wang
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Yanqing Xu
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Lu Chen
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Peipei Ding
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China
| | - Jianfeng Chen
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Sun Yat-sen University Cancer Center, Guangzhou, China.,Guangdong Key Laboratory of Nasopharyngeal Carcinoma Diagnosis and Therapy, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Weiguo Hu
- Fudan University Shanghai Cancer Center and Institutes of Biomedical Sciences, Shanghai Medical College, Fudan University, Shanghai, China.,Key Laboratory of Breast Cancer in Shanghai, Fudan University Shanghai Cancer Center, Fudan University, Shanghai, China
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4
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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: 33] [Impact Index Per Article: 11.0] [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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5
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Zhu H, Yu X, Zhang S, Shu K. Targeting the Complement Pathway in Malignant Glioma Microenvironments. Front Cell Dev Biol 2021; 9:657472. [PMID: 33869223 PMCID: PMC8047198 DOI: 10.3389/fcell.2021.657472] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 03/12/2021] [Indexed: 12/12/2022] Open
Abstract
Malignant glioma is a highly fatal type of brain tumor, and its reoccurrence is largely due to the ordered interactions among the components present in the complex microenvironment. Besides its role in immune surveillance and clearance under physiological conditions, the complement system is expressed in a variety of tumor types and mediates the interactions within the tumor microenvironments. Recent studies have uncovered the broad expression spectrum of complement signaling molecules in the tumor microenvironment and various tumor cells, in particular, malignant glioma cells. Involvement of the complement system in tumor growth, immunosuppression and phenotype transition have also been elucidated. In this review, we enumerate the expression and function of complement molecules in multiple tumor types reported. Moreover, we elaborate the complement pathways in glioma cells and various components of malignant glioma microenvironments. Finally, we summarize the possibility of the complement molecules as prognostic factors and therapeutic targets in the treatment of malignant glioma. Specific targeting of the complement system maybe of great significance and value in the future treatment of multi-type tumors including malignant glioma.
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Affiliation(s)
- Hongtao Zhu
- Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Department of Histology and Embryology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xingjiang Yu
- Department of Histology and Embryology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Suojun Zhang
- Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Kai Shu
- Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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6
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Ma Y, Liu Y, Zhang Z, Yang GY. Significance of Complement System in Ischemic Stroke: A Comprehensive Review. Aging Dis 2019; 10:429-462. [PMID: 31011487 PMCID: PMC6457046 DOI: 10.14336/ad.2019.0119] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 01/19/2019] [Indexed: 12/14/2022] Open
Abstract
The complement system is an essential part of innate immunity, typically conferring protection via eliminating pathogens and accumulating debris. However, the defensive function of the complement system can exacerbate immune, inflammatory, and degenerative responses in various pathological conditions. Cumulative evidence indicates that the complement system plays a critical role in the pathogenesis of ischemic brain injury, as the depletion of certain complement components or the inhibition of complement activation could reduce ischemic brain injury. Although multiple candidates modulating or inhibiting complement activation show massive potential for the treatment of ischemic stroke, the clinical availability of complement inhibitors remains limited. The complement system is also involved in neural plasticity and neurogenesis during cerebral ischemia. Thus, unexpected side effects could be induced if the systemic complement system is inhibited. In this review, we highlighted the recent concepts and discoveries of the roles of different kinds of complement components, such as C3a, C5a, and their receptors, in both normal brain physiology and the pathophysiology of brain ischemia. In addition, we comprehensively reviewed the current development of complement-targeted therapy for ischemic stroke and discussed the challenges of bringing these therapies into the clinic. The design of future experiments was also discussed to better characterize the role of complement in both tissue injury and recovery after cerebral ischemia. More studies are needed to elucidate the molecular and cellular mechanisms of how complement components exert their functions in different stages of ischemic stroke to optimize the intervention of targeting the complement system.
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Affiliation(s)
- Yuanyuan Ma
- 1Department of Neurology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,2Med-X Research Institute and School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Yanqun Liu
- 3Department of Neurology, Changhai Hospital, Second Military Medical University, Shanghai, China
| | - Zhijun Zhang
- 2Med-X Research Institute and School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
| | - Guo-Yuan Yang
- 1Department of Neurology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,2Med-X Research Institute and School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai, China
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7
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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: 142] [Impact Index Per Article: 23.7] [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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8
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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9
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 928] [Impact Index Per Article: 154.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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10
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Karsten CM, Wiese AV, Mey F, Figge J, Woodruff TM, Reuter T, Scurtu O, Kordowski A, Almeida LN, Briukhovetska D, Quell KM, Sun J, Ender F, Schmudde I, Vollbrandt T, Laumonnier Y, Köhl J. Monitoring C5aR2 Expression Using a Floxed tdTomato-C5aR2 Knock-In Mouse. THE JOURNAL OF IMMUNOLOGY 2017; 199:3234-3248. [PMID: 28864475 DOI: 10.4049/jimmunol.1700710] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 08/10/2017] [Indexed: 12/23/2022]
Abstract
The biological significance of C5a receptor [(C5aR)2/C5L2], a seven-transmembrane receptor binding C5a and C5adesArg, remains ill-defined. Specific ligation of C5aR2 inhibits C5a-induced ERK1/2 activation, strengthening the view that C5aR2 regulates C5aR1-mediated effector functions. Although C5aR2 and C5aR1 are often coexpressed, a detailed picture of C5aR2 expression in murine cells and tissues is still lacking. To close this gap, we generated a floxed tandem dye (td)Tomato-C5aR2 knock-in mouse that we used to track C5aR2 expression in tissue-residing and circulating immune cells. We found the strongest C5aR2 expression in the brain, bone marrow, and airways. All myeloid-derived cells expressed C5aR2, although with different intensities. C5aR2 expression in blood and tissue neutrophils was strong and homogeneous. Specific ligation of C5aR2 in neutrophils from tdTomato-C5aR2 mice blocked C5a-driven ERK1/2 phosphorylation, demonstrating functionality of C5aR2 in the reporter mice. In contrast to neutrophils, we found tissue-specific differences in C5aR2 expression in eosinophils, macrophages, and dendritic cell subsets. Naive and activated T cells stained negative for C5aR2, whereas B cells from different tissues homogeneously expressed C5aR2. Also, NK cell subsets in blood and spleen strongly expressed C5aR2. Activation of C5aR2 in NK cells suppressed IL-12/IL-18-induced IFN-γ production. Intratracheal IL-33 challenge resulted in decreased C5aR2 expression in pulmonary eosinophils and monocyte-derived dendritic cells. In summary, we provide a detailed map of murine C5aR2 immune cell expression in different tissues under steady-state conditions and upon pulmonary inflammation. The C5aR2 knock-in mouse will help to reliably track and conditionally delete C5aR2 expression in experimental models of inflammation.
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Affiliation(s)
- Christian M Karsten
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany;
| | - Anna V Wiese
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Fabian Mey
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Julia Figge
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Trent M Woodruff
- School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Tom Reuter
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Olga Scurtu
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Anna Kordowski
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Larissa N Almeida
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Daria Briukhovetska
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Katharina M Quell
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Jing Sun
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Fanny Ender
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Inken Schmudde
- Institute of Anatomy, University of Lübeck, Lübeck 23562, Germany
| | - Tillman Vollbrandt
- Cell Analysis Core Facility, University of Lübeck, Lübeck 23562, Germany; and
| | - Yves Laumonnier
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany
| | - Jörg Köhl
- Institute for Systemic Inflammation Research, University of Lübeck, Lübeck 23562, Germany; .,Division of Immunobiology, Cincinnati Children's Hospital and College of Medicine, University of Cincinnati, Cincinnati, OH 45229
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11
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The Controversial C5a Receptor C5aR2: Its Role in Health and Disease. J Immunol Res 2017; 2017:8193932. [PMID: 28706957 PMCID: PMC5494583 DOI: 10.1155/2017/8193932] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/11/2017] [Indexed: 01/24/2023] Open
Abstract
After the discovery of the C5a receptor C5aR1, C5aR2 is the second receptor found to bind C5a and its des-arginine form. As a heptahelical G protein-coupled receptor but devoid of the intracellular Gα signal, C5aR2 is special and confusing. Ramifications and controversies about C5aR2 are under debate since its identification, from putative ligands and cellular localization to intracellular signals and pathological roles in inflammation and immunity. The ruleless and even conflicting pro- or anti-inflammatory role of C5aR2 in animal models of diverse diseases makes one bewildered. This review summarizes reports on C5aR2, tries to clear up available evidence on these four controversial aspects, and delineates C5aR2 function(s). It also summarizes available toolboxes for C5aR2 study.
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12
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Novel insights into the expression pattern of anaphylatoxin receptors in mice and men. Mol Immunol 2017; 89:44-58. [PMID: 28600003 DOI: 10.1016/j.molimm.2017.05.019] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 05/22/2017] [Accepted: 05/23/2017] [Indexed: 02/06/2023]
Abstract
The anaphylatoxins (AT) C3a and C5a play important roles as mediators of inflammation. Further, they regulate and control multiple innate and adaptive immune responses through binding and activation of their cognate G protein-coupled receptors, i.e. C3a receptor (C3aR), C5a receptor 1 (C5aR1) and C5a receptor 2 (C5aR2), although the latter lacks important sequence motifs for G protein-coupling. Based on their pleiotropic functions, they contribute not only to tissue homeostasis but drive, perpetuate and resolve immune responses in many inflammatory diseases including infections, malignancies, autoimmune as well as allergic diseases. During the past few years, transcriptome expression data provided detailed insights into AT receptor tissue mRNA expression. In contrast, our understanding of cellular AT receptor expression in human and mouse tissues under steady and inflammatory conditions is still sketchy. Ligand binding studies, flow cytometric and immunohistochemical analyses convincingly demonstrated tissue-specific C5aR1 expression in various cells of myeloid origin. However, a detailed map for C3aR or C5aR2 expression in human or mouse tissue cells is still lacking. Also, reports about AT expression in lymphoid cells is still controversial. To understand the multiple roles of the ATs in the innate and adaptive immune networks, a detailed understanding of their receptor expression in health and disease is required. Recent findings obtained with novel GFP or tdTomato AT-receptor knock-in mice provide detailed insights into their expression pattern in tissue immune and stroma cells. Here, we will provide an update about our current knowledge of AT receptor expression pattern in humans and mice.
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Abou-El-Hassan H, Zaraket H. Viral-derived complement inhibitors: current status and potential role in immunomodulation. Exp Biol Med (Maywood) 2016; 242:397-410. [PMID: 27798122 DOI: 10.1177/1535370216675772] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The complement system is one of the body's major innate immune defense mechanisms in vertebrates. Its function is to detect foreign bodies and promote their elimination through opsonisation or lysis. Complement proteins play an important role in the immunopathogenesis of several disorders. However, excessive complement activation does not confer more protection but instead leads to several autoimmune and inflammatory diseases. With inappropriate activation of the complement system, activated complement proteins and glycoproteins may damage both healthy and diseased tissues. Development of complement inhibitors represents an effective approach in controlling dysregulated complement activity and reducing disease severity, yet few studies have investigated the nature and role of novel complement inhibitory proteins of viral origin. Viral complement inhibitors have important implications in understanding the importance of complement inhibition and their role as a promising novel therapeutic approach in diseases caused by dysregulated complement function. In this review, we discuss the role and importance of complement inhibitors derived from several viruses in the scope of human inflammatory and autoimmune diseases.
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Affiliation(s)
- Hadi Abou-El-Hassan
- 1 Faculty of Medicine, American University of Beirut Medical Center, Beirut, Lebanon.,2 Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
| | - Hassan Zaraket
- 2 Center for Infectious Diseases Research, Faculty of Medicine, American University of Beirut, Beirut, Lebanon.,3 Department of Experimental Pathology, Immunology, and Microbiology, Faculty of Medicine, American University of Beirut, Beirut, Lebanon
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Rocha-Ferreira E, Hristova M. Antimicrobial peptides and complement in neonatal hypoxia-ischemia induced brain damage. Front Immunol 2015; 6:56. [PMID: 25729383 PMCID: PMC4325932 DOI: 10.3389/fimmu.2015.00056] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 01/29/2015] [Indexed: 12/22/2022] Open
Abstract
Hypoxic-ischemic encephalopathy (HIE) is a clinical condition in the neonate, resulting from oxygen deprivation around the time of birth. HIE affects 1-5/1000 live births worldwide and is associated with the development of neurological deficits, including cerebral palsy, epilepsy, and cognitive disabilities. Even though the brain is considered as an immune-privileged site, it has innate and adaptive immune response and can produce complement (C) components and antimicrobial peptides (AMPs). Dysregulation of cerebral expression of AMPs and C can exacerbate or ameliorate the inflammatory response within the brain. Brain ischemia triggers a prolonged inflammatory response affecting the progression of injury and secondary energy failure and involves both innate and adaptive immune systems, including immune-competent and non-competent cells. Following injury to the central nervous system (CNS), including neonatal hypoxia-ischemia (HI), resident microglia, and astroglia are the main cells providing immune defense to the brain in a stimulus-dependent manner. They can express and secrete pro-inflammatory cytokines and therefore trigger prolonged inflammation, resulting in neurodegeneration. Microglial cells express and release a wide range of inflammation-associated molecules including several components of the complement system. Complement activation following neonatal HI injury has been reported to contribute to neurodegeneration. Astrocytes can significantly affect the immune response of the CNS under pathological conditions through production and release of pro-inflammatory cytokines and immunomodulatory AMPs. Astrocytes express β-defensins, which can chemoattract and promote maturation of dendritic cells (DC), and can also limit inflammation by controlling the viability of these same DC. This review will focus on the balance of complement components and AMPs within the CNS following neonatal HI injury and the effect of that balance on the subsequent brain damage.
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Affiliation(s)
- Eridan Rocha-Ferreira
- Perinatal Brain Repair Group, Department of Maternal and Fetal Medicine, Institute for Women's Health, University College London , London , UK
| | - Mariya Hristova
- Perinatal Brain Repair Group, Department of Maternal and Fetal Medicine, Institute for Women's Health, University College London , London , UK
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Eadon MT, Jacob A, Cunningham PN, Quigg RJ, Garcia JGN, Alexander JJ. Transcriptional profiling reveals that C5a alters microRNA in brain endothelial cells. Immunology 2014; 143:363-73. [PMID: 24801999 DOI: 10.1111/imm.12314] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Revised: 04/11/2014] [Accepted: 05/01/2014] [Indexed: 01/10/2023] Open
Abstract
Blood-brain barrier (BBB) disturbance is a crucial occurrence in many neurological diseases, including systemic lupus erythematosus (SLE). Our previous studies showed that experimental lupus serum altered the integrity of the mouse brain endothelial layer, an important constituent of the BBB. Complement activation occurs in lupus with increased circulating complement components. Using a genomics approach, we identified the microRNA (miRNA) altered in mouse brain endothelial cells (bEnd3) by lupus serum and the complement protein, C5a. Of the 318 miRNA evaluated, 23 miRNAs were altered by lupus serum and 32 were altered by C5a alone compared with controls. Seven miRNAs (P < 0 · 05) were differentially expressed by both treatments: mmu-miR-133a*, mmu-miR-193*, mmu-miR-26b, mmu-miR-28*, mmu-miR-320a, mmu-miR-423-3p and mmu-miR-509-5p. The microarray results were validated by quantitative RT-PCR. In line with the in vitro results, expression of miR-26b and miR-28* were also significantly up-regulated in lupus mouse brain which was reduced by C5a receptor inhibition. Target prediction analysis revealed miR gene targets encoding components involved in inflammation, matrix arrangement, and apoptosis, pathways known to play important roles in central nervous system lupus. Our findings suggest that the miRNAs reported in this study may represent novel therapeutic targets in central nervous system lupus and other similar neuroinflammatory settings.
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Affiliation(s)
- Michael T Eadon
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN, USA
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: G protein-coupled receptors. Br J Pharmacol 2013; 170:1459-581. [PMID: 24517644 PMCID: PMC3892287 DOI: 10.1111/bph.12445] [Citation(s) in RCA: 505] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. G protein-coupled receptors are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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Hao J, Wang C, Yuan J, Chen M, Zhao MH. A pro-inflammatory role of C5L2 in C5a-primed neutrophils for ANCA-induced activation. PLoS One 2013; 8:e66305. [PMID: 23785491 PMCID: PMC3681967 DOI: 10.1371/journal.pone.0066305] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 05/03/2013] [Indexed: 12/21/2022] Open
Abstract
Background The complement system is crucial for the development of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). In particular, C5a and its receptor on neutrophils, CD88, play a central role. The functional role of the second receptor of C5a, C5L2, remains unclear. In the current study, we investigated the role of C5L2 in C5a-primed neutrophils for ANCA-induced activation. Methods The effect of blocking C5L2 by anti-human C5L2 blocking antibody were tested on respiratory burst and degranulation of C5a-primed neutrophils activated with ANCA, as well as on membrane-bound proteinase 3 (mPR3) and concentration of myeloperoxidase (MPO) in supernatant of C5a-primed neutrophils. An antagonist for CD88 was also employed. Results Blocking C5L2 resulted in a significantly decreased MPO concentration in the supernatant of C5a-primed neutrophils. mPR3 expression increased from 209.0±43.0 in untreated cells to 444.3±60.8 after C5a treatment (P<0.001), and decreased to 375.8±65.44, 342.2±54.3 and 313.7±43.6 by pre-incubating blocking C5L2 antibody at 2.5 µg/ml, 5 µg/ml or 10 µg/ml (compared with C5a-priming group, P<0.001, P<0.001, and P<0.001), respectively. In C5a-primed neutrophils, subsequently activating with MPO-ANCA-positive IgG, the MFI value was 425.8±160.6, which decreased to 292.8±141.2, 289.7±130.0 and 280.3±136.4 upon pre-incubation with mouse anti-human C5L2 blocking antibody at 2.5 µg/ml, 5 µg/ml or 10 µg/ml (compared with C5a-primed neutrophils, for MPO-ANCA-positive IgG-induced activation, P<0.05, P<0.05, and P<0.05), respectively. Blocking C5L2 also resulted in significantly decreased C5a-primed neutrophils for PR3-ANCA-positive IgG-induced activation. Moreover, the lactoferrin concentration in the supernant significantly decreased in pre-incubation with anti-human C5L2 blocking antibody, compared with C5a-primed neutrophils induced by PR3- or MPO-ANCA-positive IgG. Conclusions C5L2 may be implicated in the pro-inflammatory role in C5a-primed neutrophils for ANCA-induced activation.
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MESH Headings
- Antibodies, Antineutrophil Cytoplasmic/immunology
- Antibodies, Antineutrophil Cytoplasmic/metabolism
- Antibodies, Blocking/pharmacology
- Antibodies, Monoclonal/pharmacology
- Cell Degranulation/drug effects
- Cell Degranulation/immunology
- Cell Membrane/metabolism
- Complement C5a/immunology
- Culture Media, Conditioned/metabolism
- Humans
- Neutrophil Activation/drug effects
- Neutrophil Activation/immunology
- Neutrophils/drug effects
- Neutrophils/immunology
- Neutrophils/metabolism
- Peptide Hydrolases/metabolism
- Peroxidase/metabolism
- Protein Transport
- Receptor, Anaphylatoxin C5a/antagonists & inhibitors
- Receptor, Anaphylatoxin C5a/metabolism
- Receptors, Chemokine/antagonists & inhibitors
- Receptors, Chemokine/immunology
- Receptors, Chemokine/metabolism
- Respiratory Burst/drug effects
- Respiratory Burst/immunology
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Affiliation(s)
- Jian Hao
- Renal Division, Department of Medicine, Peking University, First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Peking-Tsinghua Center for Life Sciences, Beijing, China
- Renal Division, Department of Medicine, The Affiliated Hospital of Inner Mongolia Medical College Huhehot, Inner Mongolia, China
| | - Chen Wang
- Renal Division, Department of Medicine, Peking University, First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Peking-Tsinghua Center for Life Sciences, Beijing, China
| | - Jun Yuan
- Renal Division, Department of Medicine, Peking University, First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Peking-Tsinghua Center for Life Sciences, Beijing, China
| | - Min Chen
- Renal Division, Department of Medicine, Peking University, First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Peking-Tsinghua Center for Life Sciences, Beijing, China
- * E-mail:
| | - Ming-Hui Zhao
- Renal Division, Department of Medicine, Peking University, First Hospital, Peking University Institute of Nephrology, Key Laboratory of Renal Disease, Ministry of Health of China, Key Laboratory of Chronic Kidney Disease Prevention and Treatment (Peking University), Ministry of Education, Peking-Tsinghua Center for Life Sciences, Beijing, China
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Järlestedt K, Rousset CI, Ståhlberg A, Sourkova H, Atkins AL, Thornton C, Barnum SR, Wetsel RA, Dragunow M, Pekny M, Mallard C, Hagberg H, Pekna M. Receptor for complement peptide C3a: a therapeutic target for neonatal hypoxic‐ischemic brain injury. FASEB J 2013; 27:3797-804. [DOI: 10.1096/fj.13-230011] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
| | | | - Anders Ståhlberg
- Center for Brain Repair and RehabilitationDepartment of Clinical Neuroscience and RehabilitationInstitute of Neuroscience and PhysiologySahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Hana Sourkova
- Center for Brain Repair and RehabilitationDepartment of Clinical Neuroscience and RehabilitationInstitute of Neuroscience and PhysiologySahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Alison L. Atkins
- Center for Brain Repair and RehabilitationDepartment of Clinical Neuroscience and RehabilitationInstitute of Neuroscience and PhysiologySahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | | | - Scott R. Barnum
- Department of MicrobiologyUniversity of AlabamaBirminghamAlabamaUSA
| | - Rick A. Wetsel
- Research Center for Immunology and Autoimmune DiseasesInstitute of Molecular Medicine for the Prevention of Human DiseasesUniversity of Texas‐HoustonHoustonTexasUSA
| | - Mike Dragunow
- Department of PharmacologyFaculty of Medical and Health SciencesThe University of AucklandAucklandNew Zealand
- The National Research Centre for Growth and DevelopmentFaculty of Medical and Health SciencesThe University of AucklandAucklandNew Zealand
| | - Milos Pekny
- Center for Brain Repair and RehabilitationDepartment of Clinical Neuroscience and RehabilitationInstitute of Neuroscience and PhysiologySahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Carina Mallard
- Perinatal CenterSahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Henrik Hagberg
- Perinatal CenterSahlgrenska AcademyUniversity of GothenburgGothenburgSweden
- Department of Obstetrics and GynecologySahlgrenska AcademyUniversity of GothenburgGothenburgSweden
- Centre for the Developing BrainKing's CollegeLondonUK
| | - Marcela Pekna
- Center for Brain Repair and RehabilitationDepartment of Clinical Neuroscience and RehabilitationInstitute of Neuroscience and PhysiologySahlgrenska AcademyUniversity of GothenburgGothenburgSweden
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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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20
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Roy C, Gupta A, Fisette A, Lapointe M, Poursharifi P, Richard D, Lu H, Lu B, Gerard N, Gerard C, Cianflone K. C5a receptor deficiency alters energy utilization and fat storage. PLoS One 2013; 8:e62531. [PMID: 23667486 PMCID: PMC3646841 DOI: 10.1371/journal.pone.0062531] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2013] [Accepted: 03/22/2013] [Indexed: 01/26/2023] Open
Abstract
OBJECTIVE To investigate the impact of whole body C5a receptor (C5aR) deficiency on energy metabolism and fat storage. DESIGN Male wildtype (WT) and C5aR knockout (C5aRKO) mice were fed a low fat (CHOW) or a high fat high sucrose diet-induced obesity (DIO) diet for 14 weeks. Body weight and food intake were measured weekly. Indirect calorimetry, dietary fatload clearance, insulin and glucose tolerance tests were also evaluated. Liver, muscle and adipose tissue mRNA gene expression were measured by RT-PCR. RESULTS At week one and 12, C5aRKO mice on DIO had increased oxygen consumption. After 12 weeks, although food intake was comparable, C5aRKO mice had lower body weight (-7% CHOW, -12% DIO) as well as smaller gonadal (-38% CHOW, -36% DIO) and inguinal (-29% CHOW, -30% DIO) fat pads than their WT counterparts. Conversely, in WT mice, C5aR was upregulated in DIO vs CHOW diets in gonadal adipose tissue, muscle and liver, while C5L2 mRNA expression was lower in C5aRKO on both diet. Furthermore, blood analysis showed lower plasma triglyceride and non-esterified fatty acid levels in both C5aRKO groups, with faster postprandial triglyceride clearance after a fatload. Additionally, C5aRKO mice showed lower CD36 expression in gonadal and muscle on both diets, while DGAT1 expression was higher in gonadal (CHOW) and liver (CHOW and DIO) and PPARγ was increased in muscle and liver. CONCLUSION These observations point towards a role (either direct or indirect) for C5aR in energy expenditure and fat storage, suggesting a dual role for C5aR in metabolism as well as in immunity.
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Affiliation(s)
- Christian Roy
- Centre de Recherche Institut Universitaire de Cardiologie & Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Abhishek Gupta
- Centre de Recherche Institut Universitaire de Cardiologie & Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Alexandre Fisette
- Centre de Recherche Institut Universitaire de Cardiologie & Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Marc Lapointe
- Centre de Recherche Institut Universitaire de Cardiologie & Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Pegah Poursharifi
- Centre de Recherche Institut Universitaire de Cardiologie & Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Denis Richard
- Centre de Recherche Institut Universitaire de Cardiologie & Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - HuiLing Lu
- Centre de Recherche Institut Universitaire de Cardiologie & Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Bao Lu
- Ina Sue Perlmutter Lab, Children’s Hospital, Harvard Medical School, Boston, Massachusetts United States of America
| | - Norma Gerard
- Ina Sue Perlmutter Lab, Children’s Hospital, Harvard Medical School, Boston, Massachusetts United States of America
| | - Craig Gerard
- Ina Sue Perlmutter Lab, Children’s Hospital, Harvard Medical School, Boston, Massachusetts United States of America
| | - Katherine Cianflone
- Centre de Recherche Institut Universitaire de Cardiologie & Pneumologie de Québec, Université Laval, Québec, Québec, Canada
- * E-mail:
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Fonseca MI, McGuire SO, Counts SE, Tenner AJ. Complement activation fragment C5a receptors, CD88 and C5L2, are associated with neurofibrillary pathology. J Neuroinflammation 2013; 10:25. [PMID: 23394121 PMCID: PMC3605123 DOI: 10.1186/1742-2094-10-25] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 01/28/2013] [Indexed: 12/30/2022] Open
Abstract
Background Alzheimer’s disease (AD) is a neurodegenerative dementia characterized by the decline of cognition and the presence of neuropathological changes including neuronal loss, neurofibrillary pathology and extracellular senile plaques. A neuroinflammatory process is also triggered and complement activation has been hypothesized to have a relevant role in this local inflammatory response. C5a, a proinflammatory anaphylatoxin generated after complement activation, exerts its chemotactic and inflammatory functions through the CD88 receptor while the more recently discovered C5L2 receptor has been postulated to have an anti-inflammatory role. Previously, we reported that a CD88 specific antagonist (PMX205) decreased the pathology and improved cognition in transgenic models of AD suggesting that C5a/C5aR interaction has an important role in the progression of the disease. Methods The present study characterizes the expression of the two receptors for C5a in human brain with confirmed post mortem diagnosis of vascular dementia (VD) or AD as well as age matched controls by immunohistochemistry and Western blot analysis using several antibodies against different epitopes of the human receptors. Results The CD88 and C5L2 antibodies revealed increased expression of both receptors in AD samples as compared to age-matched controls or VD brain tissue by Western blot and immunohistochemistry, using multiple antibodies and distinct cohorts of brain tissue. Immunostaining showed that both the C5L2 and CD88 antibodies similarly labeled abundant neurofibrillary tangles, neuropil threads and dystrophic neurites associated with plaques in the hippocampus and frontal cortex of AD cases. In contrast, little or no neuronal staining, tangles or dystrophic neurites associated with plaques were observed in control or VD brains. CD88 and C5L2 receptors are associated with both early (AT8) and mature (PHF1) neurofibrillary tangles and can be found either independently or colocalized with each other. Conclusions The observed association of CD88 and C5L2 with neurofibrillary pathology suggests a common altered pathway of degradation.
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Affiliation(s)
- Maria I Fonseca
- Dept of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697-3900, USA
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Li R, Coulthard LG, Wu MCL, Taylor SM, Woodruff TM. C5L2: a controversial receptor of complement anaphylatoxin, C5a. FASEB J 2012; 27:855-64. [PMID: 23239822 DOI: 10.1096/fj.12-220509] [Citation(s) in RCA: 147] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
C5a is the paramount proinflammatory mediator of the complement cascade, and has been previously thought to act only through a single, G-protein-coupled, C5a receptor (C5aR; also termed CD88). In 2000, a second C5a receptor, C5L2 (previously known as GPR77), was discovered; yet, despite 12 yr of intensive research, its biological, or pathophysiological, function is both enigmatic and controversial. Unlike C5aR, this receptor does not couple to G proteins, and early studies promoted the hypothesis that C5L2 functions as a decoy receptor. However, recent data have provided other evidence for more complicated and conflicting interactions between C5L2 and other inflammatory mediators. C5L2 has been recently demonstrated to physically interact with both C5aR and β-arrestin to negatively regulate C5aR signaling toward an anti-inflammatory manner, and to reduce pathology, in several disease models in vivo. In direct contrast, other groups have demonstrated that C5L2 stimulation caused release of HMGB1 both in vitro and in vivo, and enhanced pathology in sepsis models, suggesting a clear proinflammatory signaling role. These astoundingly contradictory data challenge our precepts and complicate the foundational bases for the possible targeting of C5L2 as a therapeutic option in inflammatory disease. C5L2 may be the great masquerader in complement biology; its function dependent on the cell type, species, and disease context. Because of these unusual and unforeseen complexities, we present the current state of knowledge on C5L2 structure, expression and, most controversially, its putative functions.-Li, R., Coulthard, L.G., Wu, M. C. L., Taylor, S. M., Woodruff, T. M. C5L2: a controversial receptor of complement anaphylatoxin, C5a.
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Affiliation(s)
- Rui Li
- School of Biomedical Sciences, University of Queensland, St Lucia, QLD, 4072, Australia
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Nesargikar PN, Spiller B, Chavez R. The complement system: history, pathways, cascade and inhibitors. Eur J Microbiol Immunol (Bp) 2012; 2:103-11. [PMID: 24672678 DOI: 10.1556/eujmi.2.2012.2.2] [Citation(s) in RCA: 185] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 03/26/2012] [Indexed: 01/20/2023] Open
Abstract
Since its discovery in the 19th century, the complement system has developed into a clinically significant entity. The complement system has been implicated in a variety of clinical conditions, from autoimmune diseases to ischemia-reperfusion injury in transplantation. This article charts the historical progress of our understanding of the complement system and provides a synopsis on the activation pathways and its inherent regulators.
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Bachmaier K, Guzman E, Kawamura T, Gao X, Malik AB. Sphingosine kinase 1 mediation of expression of the anaphylatoxin receptor C5L2 dampens the inflammatory response to endotoxin. PLoS One 2012; 7:e30742. [PMID: 22355325 PMCID: PMC3280265 DOI: 10.1371/journal.pone.0030742] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 12/27/2011] [Indexed: 11/30/2022] Open
Abstract
The complement anaphylatoxin C5a has a pathogenetic role in endotoxin-induced lung inflammatory injury by regulating phagocytic cell migration and activation. Endotoxin and C5a activate the enzyme sphingosine kinase (Sphk) 1 to generate the signaling lipid sphingosine-1-phosphate (S1P), a critical regulator of phagocyte function. We assessed the function of Sphk1 and S1P in experimental lung inflammatory injury and determined their roles in anaphylatoxin receptor signaling and on the expression of the two C5a receptors, C5aR (CD88) and C5L2, on phagocytes. We report that Sphk1 gene deficient (Sphk1−/−) mice had augmented lung inflammatory response to endotoxin compared to wild type mice. Sphk1 was required for C5a-mediated reduction in cytokine and chemokine production by macrophages. Moreover, neutrophils from Sphk1−/− mice failed to upregulate the anaphylatoxin receptor C5L2 in response to LPS. Exogenous S1P restored C5L2 cell surface expression of Sphk1−/− mouse neutrophils to wild type levels but had no effect on cell surface expression of the other anaphylatoxin receptor, CD88. These results provide the first genetic evidence of the crucial role of Sphk1 in regulating the balance between expression of CD88 and C5L2 in phagocytes. S1P-mediated up-regulation of C5L2 is a novel therapeutic target for mitigating endotoxin-induced lung inflammatory injury.
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Affiliation(s)
- Kurt Bachmaier
- Department of Pharmacology, College of Medicine, Center of Lung and Vascular Biology, University of Illinois, Chicago, Illinois, United States of America.
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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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Laureys G, Clinckers R, Gerlo S, Spooren A, Wilczak N, Kooijman R, Smolders I, Michotte Y, De Keyser J. Astrocytic beta(2)-adrenergic receptors: from physiology to pathology. Prog Neurobiol 2010; 91:189-99. [PMID: 20138112 DOI: 10.1016/j.pneurobio.2010.01.011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 12/07/2009] [Accepted: 01/27/2010] [Indexed: 12/24/2022]
Abstract
Evidence accumulates for a key role of the beta(2)-adrenergic receptors in the many homeostatic and neuroprotective functions of astrocytes, including glycogen metabolism, regulation of immune responses, release of neurotrophic factors, and the astrogliosis that occurs in response to neuronal injury. A dysregulation of the astrocytic beta(2)-adrenergic-pathway is suspected to contribute to the physiopathology of a number of prevalent and devastating neurological conditions such as multiple sclerosis, Alzheimer's disease, human immunodeficiency virus encephalitis, stroke and hepatic encephalopathy. In this review we focus on the physiological functions of astrocytic beta(2)-adrenergic receptors, and their possible impact in disease states.
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Affiliation(s)
- Guy Laureys
- Department of Pharmaceutical Chemistry and Drug Analysis, Vrije Universiteit Brussel, Belgium
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Crane JW, Baiquni GP, Sullivan RK, Lee JD, Sah P, Taylor SM, Noakes PG, Woodruff TM. The C5a anaphylatoxin receptor CD88 is expressed in presynaptic terminals of hippocampal mossy fibres. J Neuroinflammation 2009; 6:34. [PMID: 19917081 PMCID: PMC2780381 DOI: 10.1186/1742-2094-6-34] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2009] [Accepted: 11/16/2009] [Indexed: 12/20/2022] Open
Abstract
Background In the periphery, C5a acts through the G-protein coupled receptor CD88 to enhance/maintain inflammatory responses. In the brain, CD88 can be expressed on astrocytes, microglia and neurons. Previous studies have shown that the hippocampal CA3 region displays CD88-immunolabelling, and CD88 mRNA is present within dentate gyrus granule cells. As granule cells send dense axonal projections (mossy fibres) to CA3 pyramidal neurons, CD88 expression could be expressed on mossy fibres. However, the cellular location of CD88 within the hippocampal CA3 region is unknown. Methods The expression of CD88 within the hippocampal CA3 region was characterized using dual-immunolabelling of hippocampal sections prepared from Wistar rats. Immunolabelling for CD88, using a monoclonal antibody, was combined with immunolabelling for markers of astrocytes (GFAP), microglia (IBA1), presynaptic proteins (synaptophysin and synapsin-1) and preterminal axons (neurofilament). In addition, electron microscopy was performed on peroxidase-visualized CD88-immunolabelling to determine its cellular localisation within the CA3 region. Results Dense CD88-immunolabelling was observed within the stratum lucidum of the CA3, consistent with the presence of CD88 on mossy fibres. Labelling for CD88 rarely co-localized with astrocytes or microglia, but was highly co-localized with presynaptic proteins. Electron microscopy revealed CD88-immunolabelling was localized to large presynaptic terminals within the stratum lucidum. Conclusion These results demonstrate that CD88 is expressed on presynaptic terminals of mossy fibres within the CA3 region of the hippocampus. Although the role of CD88 on mossy fibres remains to be established, their involvement in synaptic/cellular plasticity, and in cognitive disorders such as Alzheimer's disease deserves investigation.
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Affiliation(s)
- James W Crane
- Queensland Brain Institute, The University of Queensland, St, Lucia, Brisbane, Qld, 4072 Australia.
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Anaphylatoxin and formyl peptide. Br J Pharmacol 2009. [DOI: 10.1111/j.1476-5381.2009.00501_10.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Woodruff TM, Ager RR, Tenner AJ, Noakes PG, Taylor SM. The role of the complement system and the activation fragment C5a in the central nervous system. Neuromolecular Med 2009; 12:179-92. [PMID: 19763906 DOI: 10.1007/s12017-009-8085-y] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 08/25/2009] [Indexed: 12/28/2022]
Abstract
The complement system is a pivotal component of the innate immune system which protects the host from infection and injury. Complement proteins can be induced in all cell types within the central nervous system (CNS), where the pathway seems to play similar roles in host defense. Complement activation produces the C5 cleavage fragment C5a, a potent inflammatory mediator, which recruits and activates immune cells. The primary cellular receptor for C5a, the C5a receptor (CD88), has been reported to be on all CNS cells, including neurons and glia, suggesting a functional role for C5a in the CNS. A second receptor for C5a, the C5a-like receptor 2 (C5L2), is also expressed on these cells; however, little is currently known about its potential role in the CNS. The potent immune and inflammatory actions of complement activation are necessary for host defense. However, if over-activated, or left unchecked it promotes tissue injury and contributes to brain disease pathology. Thus, complement activation, and subsequent C5a generation, is thought to play a significant role in the progression of CNS disease. Paradoxically, complement may also exert a neuroprotective role in these diseases by aiding in the elimination of aggregated and toxic proteins and debris which are a principal hallmark of many of these diseases. This review will discuss the expression and known roles for complement in the CNS, with a particular focus on the pro-inflammatory end-product, C5a. The possible overarching role for C5a in diseases of the CNS is reviewed, and the therapeutic potential of blocking C5a/CD88 interaction is evaluated.
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Affiliation(s)
- Trent M Woodruff
- School of Biomedical Sciences, University of Queensland, St. Lucia, Brisbane, 4072, Australia.
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Fonseca MI, Ager RR, Chu SH, Yazan O, Sanderson SD, LaFerla FM, Taylor SM, Woodruff TM, Tenner AJ. Treatment with a C5aR antagonist decreases pathology and enhances behavioral performance in murine models of Alzheimer's disease. THE JOURNAL OF IMMUNOLOGY 2009; 183:1375-83. [PMID: 19561098 DOI: 10.4049/jimmunol.0901005] [Citation(s) in RCA: 207] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Alzheimer's disease (AD) is an age-related dementia, characterized by amyloid plaques, neurofibrillary tangles, neuroinflammation, and neuronal loss in the brain. Components of the complement system, known to produce a local inflammatory reaction, are associated with the plaques and tangles in AD brain, and thus a role for complement-mediated inflammation in the acceleration or progression of disease has been proposed. A complement activation product, C5a, is known to recruit and activate microglia and astrocytes in vitro by activation of a G protein-coupled cell-surface C5aR. Here, oral delivery of a cyclic hexapeptide C5a receptor antagonist (PMX205) for 2-3 mo resulted in substantial reduction of pathological markers such as fibrillar amyloid deposits (49-62%) and activated glia (42-68%) in two mouse models of AD. The reduction in pathology was correlated with improvements in a passive avoidance behavioral task in Tg2576 mice. In 3xTg mice, PMX205 also significantly reduced hyperphosphorylated tau (69%). These data provide the first evidence that inhibition of a proinflammatory receptor-mediated function of the complement cascade (i.e., C5aR) can interfere with neuroinflammation and neurodegeneration in AD rodent models, suggesting a novel therapeutic target for reducing pathology and improving cognitive function in human AD patients.
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Affiliation(s)
- Maria I Fonseca
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
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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: 501] [Impact Index Per Article: 33.4] [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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Arumugam TV, Woodruff TM, Lathia JD, Selvaraj PK, Mattson MP, Taylor SM. Neuroprotection in stroke by complement inhibition and immunoglobulin therapy. Neuroscience 2009; 158:1074-89. [PMID: 18691639 PMCID: PMC2639633 DOI: 10.1016/j.neuroscience.2008.07.015] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 07/08/2008] [Accepted: 07/08/2008] [Indexed: 12/18/2022]
Abstract
Activation of the complement system occurs in a variety of neuroinflammatory diseases and neurodegenerative processes of the CNS. Studies in the last decade have demonstrated that essentially all of the activation components and receptors of the complement system are produced by astrocytes, microglia, and neurons. There is also rapidly growing evidence to indicate an active role of the complement system in cerebral ischemic injury. In addition to direct cell damage, regional cerebral ischemia and reperfusion (I/R) induces an inflammatory response involving complement activation and generation of active fragments, such as C3a and C5a anaphylatoxins, C3b, C4b, and iC3b. The use of specific inhibitors to block complement activation or their mediators such as C5a, can reduce local tissue injury after I/R. Consistent with therapeutic approaches that have been successful in models of autoimmune disorders, many of the same complement inhibition strategies are proving effective in animal models of cerebral I/R injury. One new form of therapy, which is less specific in its targeting of complement than monodrug administration, is the use of immunoglobulins. Intravenous immunoglobulin (IVIG) has the potential to inhibit multiple components of inflammation, including complement fragments, pro-inflammatory cytokine production and leukocyte cell adhesion. Thus, IVIG may directly protect neurons, reduce activation of intrinsic inflammatory cells (microglia) and inhibit transendothelial infiltration of leukocytes into the brain parenchyma following an ischemic stroke. The striking neuroprotective actions of IVIG in animal models of ischemic stroke suggest a potential therapeutic potential that merits consideration for clinical trials in stroke patients.
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Affiliation(s)
- T V Arumugam
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, 1300 Coulter Drive, Amarillo, TX 79106, USA.
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Ward PA. Functions of C5a receptors. J Mol Med (Berl) 2009; 87:375-8. [PMID: 19189071 DOI: 10.1007/s00109-009-0442-7] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2008] [Revised: 01/14/2009] [Accepted: 01/15/2009] [Indexed: 11/30/2022]
Abstract
The split product of the complement protein, C5, is C5a and is an extremely potent pro-inflammatory peptide that interacts with two C5a receptors, C5aR and C5L2, present on surfaces of phagocytes as well as other cell types. The former is a well-established receptor that initiates G-protein-coupled signaling via mitogen-activated protein kinase pathways. Its in vivo blockade greatly reduces inflammatory injury. Much less is known about C5L2, occupancy of which by C5a does not initiate increased intracellular Ca(2+). There are numerous conflicting reports suggesting that C5L2 is a "default receptor" that attenuates C5a-dependent biological responses by competing with C5aR for binding of C5a. However, there are other reports suggesting that C5L2 plays an active, positive role in inflammatory responses. Better definition of C5L2 is needed if its in vivo blockade, along with C5aR, is to be considered in complement-dependent inflammatory diseases.
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Affiliation(s)
- Peter A Ward
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, 48109-0602, USA.
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The human complement fragment receptor, C5L2, is a recycling decoy receptor. Mol Immunol 2008; 46:1149-62. [PMID: 19100624 PMCID: PMC2697321 DOI: 10.1016/j.molimm.2008.11.001] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Revised: 10/31/2008] [Accepted: 11/01/2008] [Indexed: 12/16/2022]
Abstract
C5L2 is a 7 transmembrane domain receptor for complement fragment C5a that, unlike the classical C5a receptor, C5aR, does not couple to G proteins. However, in mice where C5L2 has been deleted, the response to C5a is altered, suggesting that C5L2 may have a signaling function. In order to investigate whether human C5L2 also has some capacity to transduce signals, we have attempted to produce a signaling competent form of human C5L2 by inserting C5aR sequences at three key G protein activation motifs. However, we detected neither an intracellular Ca2+ response nor β-arrestin redistribution in mutated C5L2, suggesting that the potential for G protein coupling is completely absent in this receptor and that, in humans, C5L2 may have functions that are unrelated to signaling. In confirmation of this, we detected constitutive ligand-independent internalization of C5L2 that resulted in the rapid accumulation of C5a and its stable metabolite, C5a des Arg, within the cell with only a small net change in cell surface receptor levels. Internalization was found to be through a clathrin-dependent mechanism that led to the retention and, in cells natively expressing C5L2, the degradation of the ligand within an intracellular compartment. In contrast, the classical C5a receptor, C5aR, internalized ligand much more slowly and a majority of this ligand was released back into the extracellular environment in an apparently undegraded form. These data suggest that a major function of human C5L2 is to remove active complement fragments from the extracellular environment.
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Rittirsch D, Flierl MA, Nadeau BA, Day DE, Huber-Lang M, Mackay CR, Zetoune FS, Gerard NP, Cianflone K, Köhl J, Gerard C, Sarma JV, Ward PA. Functional roles for C5a receptors in sepsis. Nat Med 2008; 14:551-7. [PMID: 18454156 DOI: 10.1038/nm1753] [Citation(s) in RCA: 304] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 03/17/2008] [Indexed: 12/17/2022]
Abstract
The function of the C5a receptors, C5ar (encoded by C5ar) and C5l2 (encoded by Gpr77), especially of C5l2, which was originally termed a 'default receptor', remains a controversial topic. Here we investigated the role of each receptor in the setting of cecal ligation and puncture-induced sepsis by using antibody-induced blockade of C5a receptors and knockout mice. In 'mid-grade' sepsis (30-40% survival), blockade or absence of either C5ar or C5l2 greatly improved survival and attenuated the buildup of proinflammatory mediators in plasma. In vivo appearance or in vitro release of high mobility group box 1 protein (HMGB1) required C5l2 but not C5ar. In 'high-grade' sepsis (100% lethality), the only protective condition was the combined blockade of C5l2 and C5ar. These data suggest that C5ar and C5l2 contribute synergistically to the harmful consequences in sepsis and that C5l2 is required for the release of HMGB1. Thus, contrary to earlier speculation, C5l2 is a functional receptor rather than merely a default receptor.
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Affiliation(s)
- Daniel Rittirsch
- Department of Pathology, University of Michigan Medical School, 1301 Catherine Road, Ann Arbor, Michigan 48109, USA
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Food Intake Regulation by Central Complement System. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008. [DOI: 10.1007/978-0-387-78952-1_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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MacLaren R, Cui W, Cianflone K. Adipokines and the immune system: an adipocentric view. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 632:1-21. [PMID: 19025110 DOI: 10.1007/978-0-387-78952-1_1] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
There is increasing evidence of close interactions between the adipose and the immune systems. Adipocytes secrete multiple factors, including adipokines such as leptin and adiponectin that have both pro- and anti-inflammatory effects, and influence diseases involving the immune system. Further, adipose tissue also secretes various chemokines and cytokines, derived from either the adipocytes themselves, or the neighbouring cells including both resident and infiltrating macrophages. This close physical and paracrine interaction results in reciprocal actions of adipocytes, preadipocytes and macrophages within the microenvironment of the adipose tissue. Adipose tissue is a source of Acylation Stimulating Protein (ASP)/C3adesArg which interacts with the receptor C5L2 to stimulate triglyceride synthesis and glucose transport. C5L2, present on adipocytes, preadipocytes, macrophages, and numerous other myeloid and non-myeloid cells is also postulated to be a decoy receptor for C5a in immune cells. Several reviews within the past year have recently examined the role of C5L2 in C5a-mediated physiology. The present mini-review is an adipocentric view with emphasis on the role of ASP and C5L2 in lipid metabolism. C5L2 may play a role in mediating, on one hand, ASP stimulation of triglyceride synthesis in adipose, and, on the other hand, a role as mediator of C5a immune function. Both roles remain controversial, and will only be resolved with further studies.
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Affiliation(s)
- Robin MacLaren
- Department of Experimental Medicine, McGill University, Montreal, Canada
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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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Monk PN, Scola AM, Madala P, Fairlie DP. Function, structure and therapeutic potential of complement C5a receptors. Br J Pharmacol 2007; 152:429-48. [PMID: 17603557 PMCID: PMC2050825 DOI: 10.1038/sj.bjp.0707332] [Citation(s) in RCA: 297] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Complement fragment (C)5a is a 74 residue pro-inflammatory polypeptide produced during activation of the complement cascade of serum proteins in response to foreign surfaces such as microorganisms and tissue damaged by physical or chemical injury. C5a binds to at least two seven-transmembrane domain receptors, C5aR (C5R1, CD88) and C5L2 (gpr77), expressed ubiquitously on a wide variety of cells but particularly on the surface of immune cells like macrophages, neutrophils and T cells. C5aR is a classical G protein-coupled receptor that signals through G alpha i and G alpha 16, whereas C5L2 does not appear to couple to G proteins and has no known signalling activity. Although C5a was first described as an anaphylatoxin and later as a leukocyte chemoattractant, the widespread expression of C5aR suggested more general functionality. Our understanding of the physiology of C5a has improved significantly in recent years through exploitation of receptor knockout and knocking mice, C5 and C5a antibodies, soluble recombinant C5a and C5a analogues and newly developed receptor antagonists. C5a is now also implicated in non-immunological functions associated with developmental biology, CNS development and neurodegeneration, tissue regeneration, and haematopoiesis. Combined receptor mutagenesis, molecular modelling, structure-activity relationship studies and species dependence for ligand potency on C5aR have been helpful for identifying ligand binding sites on the receptor and for defining mechanisms of receptor activation and inactivation. This review will highlight major developments in C5a receptor research that support C5aR as an important therapeutic target. The intriguing possibilities raised by the existence of a non-signalling C5a receptor are also discussed.
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Affiliation(s)
- P N Monk
- Academic Neurology Unit, School of Medicine and Biomedical Science, University of Sheffield, Sheffield, UK.
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Rabiet MJ, Huet E, Boulay F. The N-formyl peptide receptors and the anaphylatoxin C5a receptors: an overview. Biochimie 2007; 89:1089-106. [PMID: 17428601 PMCID: PMC7115771 DOI: 10.1016/j.biochi.2007.02.015] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2006] [Accepted: 02/23/2007] [Indexed: 12/31/2022]
Abstract
Leukocyte recruitment to sites of inflammation and infection is dependent on the presence of a gradient of locally produced chemotactic factors. This review is focused on current knowledge about the activation and regulation of chemoattractant receptors. Emphasis is placed on the members of the N-formyl peptide receptor family, namely FPR (N-formyl peptide receptor), FPRL1 (FPR like-1) and FPRL2 (FPR like-2), and the complement fragment C5a receptors (C5aR and C5L2). Upon chemoattractant binding, the receptors transduce an activation signal through a G protein-dependent pathway, leading to biochemical responses that contribute to physiological defense against bacterial infection and tissue damage. C5aR, and the members of the FPR family that were previously thought to be restricted to phagocytes proved to have a much broader spectrum of cell expression. In addition to N-formylated peptides, numerous unrelated ligands were recently found to interact with FPR and FPRL1. Novel agonists include both pathogen- and host-derived components, and synthetic peptides. Antagonistic molecules have been identified that exhibit limited receptor specificity. How distinct ligands can both induce different biological responses and produce different modes of receptor activation and unique sets of cellular responses are discussed. Cell responses to chemoattractants are tightly regulated at the level of the receptors. This review describes in detail the regulation of receptor signalling and the multi-step process of receptor inactivation. New concepts, such as receptor oligomerization and receptor clustering, are considered. Although FPR, FPRL1 and C5aR trigger similar biological functions and undergo a rapid chemoattractant-mediated phosphorylation, they appear to be differentially regulated and experience different intracellular fates.
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Affiliation(s)
| | | | - François Boulay
- Corresponding author. Tel.: +33 438 78 31 38; fax: +33 438 78 51 85.
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Chen NJ, Mirtsos C, Suh D, Lu YC, Lin WJ, McKerlie C, Lee T, Baribault H, Tian H, Yeh WC. C5L2 is critical for the biological activities of the anaphylatoxins C5a and C3a. Nature 2007; 446:203-7. [PMID: 17322907 DOI: 10.1038/nature05559] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Accepted: 12/27/2006] [Indexed: 12/13/2022]
Abstract
Complement-derived anaphylatoxins regulate immune and inflammatory responses through G-protein-coupled receptor (GPCR)-mediated signalling. C5L2 (also known as GPR77) is a relatively new GPCR thought to be a non-signalling receptor binding to C5a, on the basis of sequence information and experimental evidence. Here we show, using gene targeting, that C5L2 is required to facilitate C5a signalling in neutrophils, macrophages and fibroblasts in vitro. Deficiency of C5L2 results in reduced inflammatory cell infiltration, suggesting that C5L2 is critical for optimal C5a-mediated cell infiltration in certain in vivo settings. C5L2 is also involved in optimizing C3a-induced signals. Furthermore, like mice incapable of C3a/complement 3a receptor (C3aR) signalling, C5L2-deficient mice are hypersensitive to lipopolysaccharide (LPS)-induced septic shock, show reduced ovalbumin (OVA)-induced airway hyper-responsiveness and inflammation, and are mildly delayed in haematopoietic cell regeneration after gamma-irradiation. Our data indicate that C5L2 can function as a positive modulator for both C5a- and C3a-anaphylatoxin-induced responses.
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Affiliation(s)
- Nien-Jung Chen
- The Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, University Health Network and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2C1, Canada
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43
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Scola AM, Higginbottom A, Partridge LJ, Reid RC, Woodruff T, Taylor SM, Fairlie DP, Monk PN. The role of the N-terminal domain of the complement fragment receptor C5L2 in ligand binding. J Biol Chem 2006; 282:3664-71. [PMID: 17158873 PMCID: PMC2873560 DOI: 10.1074/jbc.m609178200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
C5L2 is a new cellular receptor found to interact with the human anaphylatoxins complement factor C5a and its C-terminal cleavage product C5a des Arg. The classical human C5a receptor (C5aR) preferentially binds C5a, with a 10-100-fold lower affinity for C5a des Arg. In contrast, C5L2 binds both ligands with nearly equal affinity. C5aR presents acidic and tyrosine residues in its N terminus that interact with the core of C5a while a hydrophobic pocket formed by the transmembrane helices interacts with residues in the C terminus of C5a. Here, we have investigated the molecular basis for the increased affinity of C5L2 for C5a des Arg. Rat and mouse C5L2 preferentially bound C5a des Arg, whereas rodent C5aR showed much higher affinity for intact C5a. Effective peptidic and non-peptidic ligands for the transmembrane hydrophobic pocket of C5aR were poor inhibitors of ligand binding to C5L2. An antibody raised against the N terminus of human C5L2 did not affect the binding of C5a to C5L2 but did inhibit C5a des Arg binding. A chimeric C5L2, containing the N terminus of C5aR, had little effect on the affinity for C5a des Arg. Mutation of acidic and tyrosine residues in the N terminus of human C5L2 revealed that 3 residues were critical for C5a des Arg binding but had little involvement in C5a binding. C5L2 thus appears to bind C5a and C5a des Arg by different mechanisms, and, unlike C5aR, C5L2 uses critical residues in its N-terminal domain for binding only to C5a des Arg.
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Affiliation(s)
- Anne-Marie Scola
- Academic Neurology Unit and Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2RX, United Kingdom
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44
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Kalinin S, Feinstein DL, Xu HL, Huesa G, Pelligrino DA, Galea E. Degeneration of noradrenergic fibres from the locus coeruleus causes tight-junction disorganisation in the rat brain. Eur J Neurosci 2006; 24:3393-400. [PMID: 17229089 DOI: 10.1111/j.1460-9568.2006.05223.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Although functional studies demonstrate that noradrenaline controls the permeability of the blood-brain barrier, it has never been determined whether this neurotransmitter regulates the tight junction (TJ) assembly that confers the barrier property to brain microvessels. We thus tested in rats the effect of pharmacological depletion of noradrenaline with the noradrenergic toxin DSP4 (5 mg/kg) on the expression of the TJ proteins zonula occludens-1 (ZO1) and occludin. The effectiveness of the lesion was confirmed by tyrosine hydroxylase immunoreactivity, which showed noradrenergic fibre reduction accompanied by debris and swollen fibres in DSP4-treated brains. Noradrenergic fibre degeneration caused: (i) gliosis; (ii) disappearance of TJ proteins in vascular cell-to-cell contacts (49.9 and 38.3% reductions for occludin and ZO1, respectively); (iii) a 49.2% decrease in total ZO1 protein, measured by Western blot analysis, parallel to a 39.5% decrease in ZO1 mRNA, measured by real-time PCR; and (iv) a relative increase in the beta occludin isoform (62.9%), with no change in total occludin protein or mRNA. The expression of endothelial brain antigen, a marker of a functionally competent brain endothelium, was also reduced. We conclude that damage to the ascending fibres from the locus coeruleus caused TJ disruption and gliosis, a sign of inflammation. These results imply that the locus coeruleus degeneration reported in Alzheimer's and Parkinson's diseases may contribute to these disorders by causing blood-brain barrier dysfunction. Whether the vascular damage is the result of impaired noradrenergic transmission or secondary to the inflammatory reaction remains to be determined.
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Affiliation(s)
- Sergey Kalinin
- Department of Anaesthesiology, University of Illinois at Chicago, Illinois, USA
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45
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Arumugam TV, Magnus T, Woodruff TM, Proctor LM, Shiels IA, Taylor SM. Complement mediators in ischemia–reperfusion injury. Clin Chim Acta 2006; 374:33-45. [PMID: 16872589 DOI: 10.1016/j.cca.2006.06.010] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 06/08/2006] [Accepted: 06/09/2006] [Indexed: 11/28/2022]
Abstract
BACKGROUND Ischemia-reperfusion (I/R) injury occurs when a tissue is temporarily deprived of blood supply and the return of the blood supply triggers an intense inflammatory response. Pathologically, increased complement activity can cause substantial damage to blood vessels, tissues and also facilitate leukocyte activation and recruitment following I/R injury. Herein, previously published studies are reported and critically reviewed. METHODS Medline and the World Wide Web were searched and the relevant literature was classified under the following categories: (1) Complement pathways; (2) The complement system and the inflammatory response; (3) Complement in ischemia-reperfusion injuries; and (4) Therapeutic approaches against complement in I/R injuries. RESULTS AND CONCLUSIONS I/R injury is a common clinical event with the potential to seriously affect, and sometimes kill, the patient and is a potent inducer of complement activation that results in the production of a number of inflammatory mediators. Complement activation leads to the release of biologically active potent inflammatory complement substances including the anaphylatoxins (C3a and C5a) and the cytolytic terminal membrane attack complement complex C5b-9 (MAC). The use of specific complement inhibitors to block complement activation at various levels of the cascade has been shown to prevent or reduce local tissue injury after I/R. Several agents that inhibit all or part of the complement system, such as soluble complement receptor type 1 (sCR1), C1 inhibitor (C1-INH), C5a monoclonal antibodies, a C5a receptor antagonist and soluble CD59 (sCD59) have been shown to reduce I/R injury of various organs. The novel inhibitors of complement products may eventually find wide clinical application because there are no effective drug therapies currently available to treat I/R injuries.
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Affiliation(s)
- Thiruma V Arumugam
- Laboratory of Neurosciences, National Institute on Aging Intramural Research Program, 5600 Nathan Shock Drive, Baltimore, MD 21224, USA
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46
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Woodruff TM, Crane JW, Proctor LM, Buller KM, Shek AB, de Vos K, Pollitt S, Williams HM, Shiels IA, Monk PN, Taylor SM. Therapeutic activity of C5a receptor antagonists in a rat model of neurodegeneration. FASEB J 2006; 20:1407-17. [PMID: 16816116 DOI: 10.1096/fj.05-5814com] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The complement system is thought to be involved in the pathogenesis of numerous neurological diseases, although its precise role remains controversial. In this study we used orally active C5a receptor antagonists (PMX53 and PMX205) developed in our laboratories in a rat model of 3-nitropropionic acid (3-NP) -induced Huntington's disease. Administration of the C5a antagonists (10 mg/kg/day, oral) either 48 h pre- or 48 h post-toxin significantly reduced body weight loss, anorexia, and behavioral and motor deficits associated with 3-NP intoxication. Striatal lesion size, apoptosis, neutrophil infiltration, and hemorrhage were also significantly reduced in C5a antagonist-treated rats. Immunohistochemical analysis demonstrated marked deposition of C3 and C9, and up-regulation of C5a receptors on neuronal cells at the time of lesion formation. Inhibition of prostaglandins or TNF-alpha with ibuprofen or infliximab had no effect in this model. The C5a antagonists did not affect 3-NP-induced cell death when added directly to rat striatal neuronal cultures, indicating a secondary mechanism of action in vivo. Our findings demonstrate for the first time that complement activation in the brain, particularly C5a, is a key event in the pathogenesis of this disease model, and suggest a future role for inhibitors of C5a in the treatment of neurodegenerative diseases.
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Affiliation(s)
- Trent M Woodruff
- Promics Ltd., The University of Queensland, Brisbane, QLD 4072, Australia.
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47
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Alexander SPH, Mathie A, Peters JA. Anaphylatoxin and chemotactic peptide. Br J Pharmacol 2006. [DOI: 10.1038/sj.bjp.0706519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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48
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Barnum SR, Szalai AJ. Complement and demyelinating disease: no MAC needed? ACTA ACUST UNITED AC 2006; 52:58-68. [PMID: 16443278 DOI: 10.1016/j.brainresrev.2005.12.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Revised: 12/09/2005] [Accepted: 12/15/2005] [Indexed: 12/22/2022]
Abstract
It has long been accepted that the complement system participates in the onset, evolution, and exacerbation of demyelinating disease, and it is widely suspected that this is accomplished mainly via destruction of nervous tissue by membrane attack complex (MAC)-mediated lysis of oligodendrocytes and neurons. However, recent studies using mutant mice indicate the MAC may not be so important. For example, mice lacking C5 and mice lacking the C5a receptor both develop experimental autoimmune encephalomyelitis (EAE) with the same frequency and intensity as their wild type counterparts. Also, transgenic mice that express C5a exclusively in the central nervous system (CNS) develop EAE that is not remarkably different from that in non-transgenic littermates. Since C5 is required for formation of the MAC, development of fulminant EAE in the absence of this complement protein demonstrates that non-complement-mediated mechanisms of CNS damage are operating. Paradoxically, mice lacking C3, mice lacking the C3a receptor, and mice lacking the complement receptor type 3 develop attenuated EAE, while mice that express C3a exclusively in the CNS develop severe and often fulminant EAE. Based on these newer data, we posit that C3-derived biologically active fragments, rather than C5 and the MAC, are central players in the pathophysiology of complement in EAE.
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Affiliation(s)
- Scott R Barnum
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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Gerard NP, Lu B, Liu P, Craig S, Fujiwara Y, Okinaga S, Gerard C. An Anti-inflammatory Function for the Complement Anaphylatoxin C5a-binding Protein, C5L2. J Biol Chem 2005; 280:39677-80. [PMID: 16204243 DOI: 10.1074/jbc.c500287200] [Citation(s) in RCA: 162] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
C5L2 is an enigmatic serpentine receptor that is co-expressed with the C5a receptor on many cells including polymorphonuclear neutrophils. The apparent absence of coupling of C5L2 with G proteins suggests that this receptor may modulate the biological activity of C5a, perhaps by acting as a decoy receptor. Alternatively, C5L2 may affect C5a function through formation of a heteromeric complex with the C5aR, or it may utilize a G protein-independent signaling pathway. Here we show that in mice bearing a targeted deletion of C5L2, the biological activity of C5a/C5a(desArg) is enhanced both in vivo and in vitro. The biological role of C5L2 thus appears to be limiting to the pro-inflammatory response to the anaphylatoxin. Accordingly, up-regulation of C5L2 may be of benefit in inflammatory states driven by C5a, including sepsis, asthma, cystic fibrosis, and chronic obstructive lung disease.
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Affiliation(s)
- Norma P Gerard
- Pulmonary Division, Department of Pediatrics, Children's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
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50
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Boos L, Szalai AJ, Barnum SR. C3a expressed in the central nervous system protects against LPS-induced shock. Neurosci Lett 2005; 387:68-71. [PMID: 16085360 DOI: 10.1016/j.neulet.2005.07.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2005] [Revised: 06/28/2005] [Accepted: 07/11/2005] [Indexed: 11/22/2022]
Abstract
Complement is implicated in the pathogenesis of inflammatory disorders of the central nervous system (CNS), like multiple sclerosis, Alzheimer's disease, and trauma. The anaphylatoxins C3a and C5a are thought to be the major contributors to complement-mediated inflammation in the CNS, likely mediating their effects via their ability to attract and activate leukocytes and common capacity to augment inflammation. For example, in experimental autoimmune encephalomyelitis, the animal model of multiple sclerosis, CNS-specific expression of C3a in C3a/GFAP transgenic mice renders them prone to massive cellular infiltration of the CNS and increases their mortality. In contrast, other studies have suggested that C3a can function in an anti-inflammatory fashion in the CNS, by inducing neurotrophin production and preventing NMDA-mediated neurotoxicity. To further investigate the seemingly paradoxical role of C3a in acute inflammation of the brain, we studied the pathogenesis of endotoxin shock in C3a/GFAP transgenic, C3a receptor-deficient (C3aR-/-) and C3a/GFAPxC3aR-/- mutant mice. Here we report that C3a/GFAP mice were significantly more resistant to endotoxin-induced lethality than wild-type and C3aR-/- mice. Surprisingly, C3a/GFAPxC3aR-/- hybrids were also significantly protected, indicating that C3a exerts its protective anti-inflammatory effect either directly or via an as yet unidentified non-canonical C3aR.
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Affiliation(s)
- Laura Boos
- Department of Microbiology, University of Alabama at Birmingham, 845 19th St. S., BBRB/842, Birmingham, AL 35294, USA
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