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Wang Y, Chen W, Ding S, Wang W, Wang C. Pentraxins in invertebrates and vertebrates: From structure, function and evolution to clinical applications. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2023; 149:105064. [PMID: 37734429 DOI: 10.1016/j.dci.2023.105064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Revised: 09/18/2023] [Accepted: 09/18/2023] [Indexed: 09/23/2023]
Abstract
The immune system is divided into two broad categories, consisting of innate and adaptive immunity. As recognition and effector factors of innate immunity and regulators of adaptive immune responses, lectins are considered to be important defense chemicals against microbial pathogens, cell trafficking, immune regulation, and prevention of autoimmunity. Pentraxins, important members of animal lectins, play a significant role in protecting the body from pathogen infection and regulating inflammatory reactions. They can recognize and bind to a variety of ligands, including carbohydrates, lipids, proteins, nucleic acids and their complexes, and protect the host from pathogen invasion by activating the complement cascade and Fcγ receptor pathways. Based on the primary structure of the subunit, pentraxins are divided into short and long pentraxins. The short pentraxins are comprised of C-reactive protein (CRP) and serum amyloid P (SAP), and the most important member of the long pentraxins is pentraxin 3 (PTX3). The CRP and SAP exist in both vertebrates and invertebrates, while the PTX3 may be present only in vertebrates. The major ligands and functions of CRP, SAP and PTX3 and three activation pathways involved in the complement system are summarized in this review. Their different characteristics in various animals including humans, and their evolutionary trees are analyzed. The clinical applications of CRP, SAP and PTX3 in human are reviewed. Some questions that remain to be understood are also highlighted.
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Affiliation(s)
- Yuying Wang
- School of Life Sciences, Ludong University, Yantai, 264025, People's Republic of China
| | - Wei Chen
- School of Life Sciences, Ludong University, Yantai, 264025, People's Republic of China; Yantai Productivity Promotion Center, Yantai, 264003, People's Republic of China
| | - Shuo Ding
- School of Life Sciences, Ludong University, Yantai, 264025, People's Republic of China
| | - Wenjun Wang
- School of Life Sciences, Ludong University, Yantai, 264025, People's Republic of China
| | - Changliu Wang
- School of Life Sciences, Ludong University, Yantai, 264025, People's Republic of China.
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Xing Y, Zhang D, Fang L, Wang J, Liu C, Wu D, Liu X, Wang X, Min W. Complement in Human Brain Health: Potential of Dietary Food in Relation to Neurodegenerative Diseases. Foods 2023; 12:3580. [PMID: 37835232 PMCID: PMC10572247 DOI: 10.3390/foods12193580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 09/21/2023] [Accepted: 09/25/2023] [Indexed: 10/15/2023] Open
Abstract
The complement pathway is a major component of the innate immune system, which is critical for recognizing and clearing pathogens that rapidly react to defend the body against external pathogens. Many components of this pathway are expressed throughout the brain and play a beneficial role in synaptic pruning in the developing central nervous system (CNS). However, excessive complement-mediated synaptic pruning in the aging or injured brain may play a contributing role in a wide range of neurodegenerative diseases. Complement Component 1q (C1q), an initiating recognition molecule of the classical complement pathway, can interact with a variety of ligands and perform a range of functions in physiological and pathophysiological conditions of the CNS. This review considers the function and immunomodulatory mechanisms of C1q; the emerging role of C1q on synaptic pruning in developing, aging, or pathological CNS; the relevance of C1q; the complement pathway to neurodegenerative diseases; and, finally, it summarizes the foods with beneficial effects in neurodegenerative diseases via C1q and complement pathway and highlights the need for further research to clarify these roles. This paper aims to provide references for the subsequent study of food functions related to C1q, complement, neurodegenerative diseases, and human health.
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Affiliation(s)
- Yihang Xing
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, China; (Y.X.); (D.Z.); (L.F.); (J.W.); (C.L.); (D.W.); (X.L.)
| | - Dingwen Zhang
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, China; (Y.X.); (D.Z.); (L.F.); (J.W.); (C.L.); (D.W.); (X.L.)
| | - Li Fang
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, China; (Y.X.); (D.Z.); (L.F.); (J.W.); (C.L.); (D.W.); (X.L.)
| | - Ji Wang
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, China; (Y.X.); (D.Z.); (L.F.); (J.W.); (C.L.); (D.W.); (X.L.)
| | - Chunlei Liu
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, China; (Y.X.); (D.Z.); (L.F.); (J.W.); (C.L.); (D.W.); (X.L.)
| | - Dan Wu
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, China; (Y.X.); (D.Z.); (L.F.); (J.W.); (C.L.); (D.W.); (X.L.)
| | - Xiaoting Liu
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, China; (Y.X.); (D.Z.); (L.F.); (J.W.); (C.L.); (D.W.); (X.L.)
| | - Xiyan Wang
- College of Food Science and Engineering, Jilin Agricultural University, Changchun 130118, China; (Y.X.); (D.Z.); (L.F.); (J.W.); (C.L.); (D.W.); (X.L.)
| | - Weihong Min
- College of Food and Health, Zhejiang A&F University, Hangzhou 311300, China
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3
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Zhong L, Sheng X, Wang W, Li Y, Zhuo R, Wang K, Zhang L, Hu DD, Hong Y, Chen L, Rao H, Li T, Chen M, Lin Z, Zhang YW, Wang X, Yan XX, Chen X, Bu G, Chen XF. TREM2 receptor protects against complement-mediated synaptic loss by binding to complement C1q during neurodegeneration. Immunity 2023; 56:1794-1808.e8. [PMID: 37442133 DOI: 10.1016/j.immuni.2023.06.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 10/22/2022] [Accepted: 06/19/2023] [Indexed: 07/15/2023]
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is strongly linked to Alzheimer's disease (AD) risk, but its functions are not fully understood. Here, we found that TREM2 specifically attenuated the activation of classical complement cascade via high-affinity binding to its initiator C1q. In the human AD brains, the formation of TREM2-C1q complexes was detected, and the increased density of the complexes was associated with lower deposition of C3 but higher amounts of synaptic proteins. In mice expressing mutant human tau, Trem2 haploinsufficiency increased complement-mediated microglial engulfment of synapses and accelerated synaptic loss. Administration of a 41-amino-acid TREM2 peptide, which we identified to be responsible for TREM2 binding to C1q, rescued synaptic impairments in AD mouse models. We thus demonstrate a critical role for microglial TREM2 in restricting complement-mediated synaptic elimination during neurodegeneration, providing mechanistic insights into the protective roles of TREM2 against AD pathogenesis.
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Affiliation(s)
- Li Zhong
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China.
| | - Xuan Sheng
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Wanbing Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Yanzhong Li
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Rengong Zhuo
- Xiamen Key Laboratory of Chiral Drugs, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China; Shenzhen Research Institute of Xiamen University, Shenzhen 518063, Guangdong, China
| | - Kai Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Lianshuai Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Dan-Dan Hu
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Yujuan Hong
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Linting Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Hengjun Rao
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Tingting Li
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Muyang Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Zhihao Lin
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Yun-Wu Zhang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China
| | - Xin Wang
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China; Shenzhen Research Institute of Xiamen University, Shenzhen 518063, Guangdong, China
| | - Xiao-Xin Yan
- Department of Anatomy and Neurobiology, Central South University Xiangya Medical School, Changsha 410013, Hunan, China
| | - Xiaochun Chen
- Department of Neurology, Fujian Medical University Union Hospital, Fuzhou 350001, Fujian, China; Fujian Key Laboratory of Molecular Neurology, Institute of Neuroscience, Fujian Medical University, Fuzhou 350001, Fujian, China
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Xiao-Fen Chen
- Fujian Provincial Key Laboratory of Neurodegenerative Disease and Aging Research, Institute of Neuroscience, School of Medicine, Xiamen University, Xiamen 361102, Fujian, China; Shenzhen Research Institute of Xiamen University, Shenzhen 518063, Guangdong, China.
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Ullah N, Wu Y. Regulation of Conformational Changes in C-reactive Protein Alters its Bioactivity. Cell Biochem Biophys 2022; 80:595-608. [PMID: 35997934 DOI: 10.1007/s12013-022-01089-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 08/09/2022] [Indexed: 01/08/2023]
Abstract
The acute phase C-reactive protein (CRP) is mainly synthesized and secreted by the liver in a cytokine-mediated response to infection or inflammation and circulates as a pentamer (pCRP) in plasma. Recent studies indicate that CRP is not only a marker but is directly involved in inflammation. CRP has a vital role in host defense and inflammation, metabolic function and scavenging through its ability for calcium depended binding to exogenous and endogenous molecules having phosphocholine followed by activation of the classical complement pathway. Accumulating evidence indicates that pCRP dissociates into monomeric CRP (mCRP) and most proinflammatory actions of CRP are only expressed following dissociation of its native pentameric assembly into mCRP. The dissociation of CRP into mCRP altogether promotes the ligand-binding capability. mCRP emerges to be the main conformation of CRP that participates in the regulation of local inflammation, however, little is identified concerning what triggers the significantly enhanced actions of mCRP and their binding to diverse ligands. The separation of mCRP from pCRP may be a direct relationship between CRP and inflammation. Here we review the current literature on CRP dissociation and its interaction with different ligands. The possibility to avoid the generation of the proinflammatory potential of mCRP has driven therapeutic approaches by targeting the dissociation mechanism of pCRP or inhibition of mCRP itself during inflammation.
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Affiliation(s)
- Naeem Ullah
- MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, 710061, China
| | - Yi Wu
- MOE Key Laboratory of Environment and Genes Related to Diseases, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an, 710061, China.
- Key Laboratory of Precision Medicine to Pediatric Diseases of Shaanxi Province, the Affiliated Children's Hospital, Xi'an Jiaotong University, Xi'an, China.
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Trendelenburg M. Autoantibodies against complement component C1q in systemic lupus erythematosus. Clin Transl Immunology 2021; 10:e1279. [PMID: 33968409 PMCID: PMC8082710 DOI: 10.1002/cti2.1279] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/30/2021] [Accepted: 04/01/2021] [Indexed: 12/19/2022] Open
Abstract
Systemic lupus erythematosus (SLE) is the archetype of a systemic autoimmune disease, but the multifaceted pathogenic mechanisms leading to inflammation and organ damage are not fully understood. Homozygous deficiency of complement C1q, the first component of the classical pathway of complement, is strongly associated with the development of SLE, thus pointing at a primarily protective role of C1q. However, while most SLE patients do not have hereditary C1q deficiency, there is indirect evidence for the importance of C1q in the inflammatory processes of the disease, including hypocomplementemia as a result of activation via the classical pathway, deposition of C1q in affected tissues and the occurrence of autoantibodies against C1q (anti‐C1q). The growing body of knowledge on anti‐C1q led to the establishment of a biomarker that is used in the routine clinical care of SLE patients. Exploring the binding characteristics of anti‐C1q allows to understand the mechanisms, that lead to the expression of relevant autoantigenic structures and the role of genetic as well as environmental factors. Lastly, the analysis of the pathophysiological consequences of anti‐C1q is of importance because C1q, the target of anti‐C1q, is a highly functional molecule whose downstream effects are altered by the binding of the autoantibody. This review summarises current study data on anti‐C1q and their implications for the understanding of SLE.
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Affiliation(s)
- Marten Trendelenburg
- Division of Internal Medicine University Hospital Basel Basel Switzerland.,Clinical Immunology Department of Biomedicine University of Basel Basel Switzerland
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Beulaja Manikandan S, Manikandan R, Arumugam M, Mullainadhan P. An overview on human serum lectins. Heliyon 2020; 6:e04623. [PMID: 32923708 PMCID: PMC7475231 DOI: 10.1016/j.heliyon.2020.e04623] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 07/16/2020] [Accepted: 07/31/2020] [Indexed: 01/25/2023] Open
Abstract
An extensive literature survey done on the various naturally occurring lectins in human serum upon its salient features such as methods of detection, level and sites of synthesis, binding specificity, cation dependency, modes of isolation, molecular and functional characterization way back from 1930s to till date was presented in a tabulated section. In addition, the generation of lectin and other immune molecules in vertebrates upon treatment with exogenous elicitors has also been framed in a tabular form. Furthermore, ANEW lectin induced in human serum for the very first time by an exogenous elicitor was detected, isolated and characterized by us whose features are also tabulated explicitly.
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Affiliation(s)
- S. Beulaja Manikandan
- Department of Biochemistry, Annai Veilankanni's College for Women, Saidapet, Chennai, Tamilnadu, 600015, India
| | - R. Manikandan
- Department of Zoology, University of Madras, Guindy Campus, Chennai, Tamilnadu, 600025, India
| | - M. Arumugam
- Department of Zoology, University of Madras, Guindy Campus, Chennai, Tamilnadu, 600025, India
| | - P. Mullainadhan
- Department of Zoology, University of Madras, Guindy Campus, Chennai, Tamilnadu, 600025, India
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Wu WJ, Tan Y, Liu XL, Yu F, Zhao MH. C1q A08 Is a Half-Cryptic Epitope of Anti-C1q A08 Antibodies in Lupus Nephritis and Important for the Activation of Complement Classical Pathway. Front Immunol 2020; 11:848. [PMID: 32536911 PMCID: PMC7267003 DOI: 10.3389/fimmu.2020.00848] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 04/14/2020] [Indexed: 11/21/2022] Open
Abstract
To investigate the fine epitope(s) of anti-C1q A08 antibodies and their roles in complement activation in lupus nephritis, C1q A08 and related peptides with various amino acid sequences around A08 were synthesized. Anti-C1q A08 antibodies from 10 lupus nephritis patients were purified from plasmapheresis samples, and four monoclonal antibodies against C1q A08 were screened and identified from mouse hybridoma cells, to study the fine epitope(s) of C1q A08 using ELISA and Biolayer Interferometry (BLI). The biofunction of anti-C1q A08 antibodies for complement classical pathway activation was investigated by C3 activation assay. Anti-C1q A08 antibodies and anti-C1q antibodies were also detected in the sera of female BALB/C mice immunized by C1q A08 peptides. None of the anti-C1q A08 antibodies, which were affinity purified from the 10 lupus nephritis patients, could bind intact C1q coated on microtitre plates, neither could the anti-C1q antibodies bind to C1q A08 peptides coupled on resin, indicating that the human anti-C1q antibodies and anti-C1q A08 antibodies may recognize different epitopes of C1q. One of the four C1q A08 mAbs (32-4) bound to the six amino acids of N-terminus of C1q A08, while another C1q A08 mAb (17-9) bound to eight or 10 amino acids of C-terminus of A08. The third and fourth C1q A08 mAb (1A12 and 4B11) bound to the whole sequence of A08. Only 32-4 mAb bound to the intact C1q coating on an ELISA plate, whereas 17-9 mAb, 1A12 mAb, and 4B11 mAb could not. However, using a BLI assay, 17-9 mAb, 1A12 mAb, and 4B11 mAb, but not 32-4 mAb, could bind to intact C1q. Furthermore, 1A12 mAb and 4B11 mAb, but not 32-4 and 17-9 mAb, could inhibit the activation of complement classical pathway. Anti-C1q A08 antibodies were detected in all the female BALB/C mice in the experimental group but not in the control group. Two out of six in the experimental group developed anti-C1q antibodies. C1q A08 is a half-cryptic epitope of C1q involving N-terminal six amino acids of C1q A08, and this is important to the activation of a complement classical pathway, and some anti-C1q A08 antibodies were able to prevent this process. Epitope spreading of C1q occurred in the mice immunized with C1q A08 peptides.
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Affiliation(s)
- Wen-Jun Wu
- School of Life Science, Tsinghua University, Beijing, China.,Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China.,Tsinghua-Peking Center for Life Sciences, Beijing, China
| | - Ying Tan
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China
| | - Xiao-Ling Liu
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China
| | - Feng Yu
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China.,Department of Nephrology, Peking University International Hospital, Beijing, China
| | - Ming-Hui Zhao
- Renal Division, Department of Medicine, Peking University First Hospital, Beijing, China.,Institute of Nephrology, Peking University, Beijing, China.,Key Laboratory of Renal Disease, Ministry of Health of China, Beijing, China.,Key Laboratory of Chronic Kidney Disease Prevention and Treatment, Ministry of Education of China, Beijing, China.,Tsinghua-Peking Center for Life Sciences, Beijing, China
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Ghebrehiwet B, Kandov E, Kishore U, Peerschke EIB. Is the A-Chain the Engine That Drives the Diversity of C1q Functions? Revisiting Its Unique Structure. Front Immunol 2018; 9:162. [PMID: 29459870 PMCID: PMC5807628 DOI: 10.3389/fimmu.2018.00162] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 01/18/2018] [Indexed: 12/27/2022] Open
Abstract
The immunopathological functions associated with human C1q are still growing in terms of novelty, diversity, and pathologic relevance. It is, therefore, not surprising that C1q is being recognized as an important molecular bridge between innate and adaptive immunity. The secret of this functional diversity, in turn, resides in the elegant but complex structure of the C1q molecule, which is assembled from three distinct gene products: A, B, and C, each of which has evolved from a separate and unique ancestral gene template. The C1q molecule is made up of 6A, 6B, and 6C polypeptide chains, which are held together through strong covalent and non-covalent bonds to form the 18-chain, bouquet-of-flower-like protein that we know today. The assembled C1q protein displays at least two distinct structural and functional regions: the collagen-like region (cC1q) and the globular head region (gC1q), each being capable of driving a diverse range of ligand- or receptor-mediated biological functions. What is most intriguing, however, is the observation that most of the functions appear to be predominantly driven by the A-chain of the molecule, which begs the question: what are the evolutionary modifications or rearrangements that singularly shaped the primordial A-chain gene to become a pluripotent and versatile component of the intact C1q molecule? Here, we revisit and discuss some of the known unique structural and functional features of the A-chain, which may have contributed to its versatility.
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Affiliation(s)
- Berhane Ghebrehiwet
- Departments of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Evelyn Kandov
- Departments of Medicine, Stony Brook University, Stony Brook, NY, United States
| | - Uday Kishore
- Biosciences, College of Health and Life Sciences, Brunel University London, Uxbridge, United Kingdom
| | - Ellinor I B Peerschke
- Department of Laboratory Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY, United States
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Stumpf C, Sheriff A, Zimmermann S, Schaefauer L, Schlundt C, Raaz D, Garlichs CD, Achenbach S. C-reactive protein levels predict systolic heart failure and outcome in patients with first ST-elevation myocardial infarction treated with coronary angioplasty. Arch Med Sci 2017; 13:1086-1093. [PMID: 28883850 PMCID: PMC5575231 DOI: 10.5114/aoms.2017.69327] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 02/15/2017] [Indexed: 01/14/2023] Open
Abstract
INTRODUCTION There is growing evidence that inflammation plays a pivotal role in the etiology and progression of atherosclerosis. High C-reactive protein (CRP) levels have been associated with high mortality in patients with acute myocardial infarction (AMI). Furthermore, in animal models CRP has been found to significantly increase infarct size. So there is growing evidence that CRP is not only a marker for cardiovascular disease but also might be pathogenic. The aim of our study was to test the hypothesis that peak CRP levels could predict heart failure (HF) in ST-elevation myocardial infarction (STEMI) patients. MATERIAL AND METHODS Eighty-one consecutive patients with STEMI were prospectively enrolled in the study. C-reactive protein concentrations were measured on admission and after 6, 12, 24, 30, 48, 72 and 96 h. We assessed the association between the elevation of CRP, heart failure and cardiovascular mortality following the first 12 months after STEMI. RESULTS C-reactive protein levels reached a peak after 48 h. Patients with STEMI and signs of HF showed significantly higher peak CRP levels. We found a positive correlation between maximum CK levels and peak CRP and a negative correlation between left ventricular ejection fraction (EF) and peak CRP. One year total mortality and HF mortality rates were found to be higher in patients with peak CRP > 47.5 mg/l than in those with CRP below that level (p < 0.001). CONCLUSIONS Peak CRP levels in STEMI patients predict emergence of HF. Peak CRP is also a strong predictor of global and cardiovascular mortality during the following year after STEMI.
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Affiliation(s)
- Christian Stumpf
- Department of Cardiology, University of Erlangen-Nuremberg, Erlangen, Germany
- Department of Cardiology, Klinikum Bayreuth, Germany
| | - Ahmed Sheriff
- Department of Nephrology and Intensive Care Medicine, Charité Berlin, Germany
| | | | - Liane Schaefauer
- Department of Cardiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Christian Schlundt
- Department of Cardiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Dorette Raaz
- Department of Cardiology, University of Erlangen-Nuremberg, Erlangen, Germany
| | | | - Stephan Achenbach
- Department of Cardiology, University of Erlangen-Nuremberg, Erlangen, Germany
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10
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Chen Y, Sha Z, Wu S, Chen S, Zeng Y. Does the different domain in sghC1q protein from Cynoglossus semilaevis perform functions independent? GENE REPORTS 2017. [DOI: 10.1016/j.genrep.2017.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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11
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Serum A08 C1q antibodies are associated with disease activity and prognosis in Chinese patients with lupus nephritis. Kidney Int 2016; 90:1357-1367. [PMID: 27745701 DOI: 10.1016/j.kint.2016.08.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 07/20/2016] [Accepted: 08/11/2016] [Indexed: 12/16/2022]
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by overproduction of numerous autoantibodies. Many studies have sought to identify such biomarkers to distinguish patients with active lupus nephritis from SLE patients without renal involvement. Because antibodies to complement C1q appear to be prevalent in patients with active lupus nephritis, we analyzed the frequency of antigenic epitopes of C1q and their clinical significance in a large multicenter study of Chinese patients. The lupus cohort consisted of 210 patients with active lupus nephritis as a discovery cohort, 130 active patients as a validation cohort along with 130 SLE patients without clinical renal involvement, and 100 healthy controls. Serum antibodies to intact C1q, the collagen-like region, the globular head region, and the new linear A08 epitope to C1q were screened by specific ELISA. The frequency of antibodies to intact C1q, the C1q-collagen-like region, and the A08 antibodies in the discovery cohort were significantly higher than that in patients without renal involvement or healthy controls. Antibodies to the globular head region were not prevalent enough for further study. The results were confirmed in the validation cohort. The area under the curve for anti-A08 antibodies was significantly greater than those for both the intact and collagen-like region antibodies to discriminate between active lupus nephritis and active SLE without clinical renal involvement. The A08 antibodies were all negative at remission. The serum A08 antibody level correlated better with disease relapse than that of antibodies to either the intact or the collagen-like region, significantly predicting renal prognosis. Thus, serum levels of A08 C1q antibodies are closely associated with disease activity and prognosis in lupus nephritis.
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Pednekar L, Valentino A, Ji Y, Tumma N, Valentino C, Kadoor A, Hosszu KK, Ramadass M, Kew RR, Kishore U, Peerschke EIB, Ghebrehiwet B. Identification of the gC1qR sites for the HIV-1 viral envelope protein gp41 and the HCV core protein: Implications in viral-specific pathogenesis and therapy. Mol Immunol 2016; 74:18-26. [PMID: 27111569 DOI: 10.1016/j.molimm.2016.03.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/25/2016] [Accepted: 03/30/2016] [Indexed: 12/27/2022]
Abstract
A substantial body of evidence accumulated over the past 20 years supports the concept that gC1qR is a major pathogen-associated pattern recognition receptor (PRR). This conclusion is based on the fact that, a wide range of bacterial and viral ligands are able to exploit gC1qR to either suppress the host's immune response and thus enhance their survival, or to gain access into cells to initiate disease. Of the extensive array of viral ligands that have affinity for gC1qR, the HIV-1 envelope glycoprotein gp41, and the core protein of hepatitis C virus (HCV) are of major interest as they are known to contribute to the high morbidity and mortality caused by these pathogens. While the HCV core protein binds gC1qR and suppresses T cell proliferation resulting in a significantly diminished immune response, the gp41 employs gC1qR to induce the surface expression of the NK cell ligand, NKp44L, on uninfected CD4(+) T cells, thereby rendering them susceptible to autologous destruction by NKp44 receptor expressing NK cells. Because of the potential for the design of peptide-based or antibody-based therapeutic options, the present studies were undertaken to define the gC1qR interaction sites for these pathogen-associated molecular ligands. Employing a solid phase microplate-binding assay, we examined the binding of each viral ligand to wild type gC1qR and 11 gC1qR deletion mutants. The results obtained from these studies have identified two major HCV core protein sites on a domain of gC1qR comprising of residues 144-148 and 196-202. Domain 196-202 in turn, is located in the last half of the larger gC1qR segment encoded by exons IV-VI (residues 159-282), which was proposed previously to contain the site for HCV core protein. The major gC1qR site for gp41 on the other hand, was found to be in a highly conserved region encoded by exon IV and comprises of residues 174-180. Interestingly, gC1qR residues 174-180 also constitute the cell surface-binding site for soluble gC1qR (sgC1qR), which can bind to the cell surface in an autocrine/paracrine manner via surface expressed fibrinogen or other membrane molecules. The identification of the sites for these viral ligands should therefore provide additional targets for the design of peptide-based or antigen-based therapeutic strategies.
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Affiliation(s)
- Lina Pednekar
- Center for Infection, Immunity and Disease Mechanisms, Biosciences, Brunel University, Uxbridge, UB8 3PH London, UK; The Departments of Medicine, Stony Brook University, Stony Brook, NY 11794, United States
| | - Alisa Valentino
- The Departments of Medicine, Stony Brook University, Stony Brook, NY 11794, United States
| | - Yan Ji
- The Departments of Medicine, Stony Brook University, Stony Brook, NY 11794, United States
| | - Nithin Tumma
- The Departments of Pathology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Christopher Valentino
- The Departments of Medicine, Stony Brook University, Stony Brook, NY 11794, United States
| | - Adarsh Kadoor
- Center for Infection, Immunity and Disease Mechanisms, Biosciences, Brunel University, Uxbridge, UB8 3PH London, UK; The Departments of Medicine, Stony Brook University, Stony Brook, NY 11794, United States; The Departments of Pathology, Stony Brook University, Stony Brook, NY 11794, United States; The Department of Laboratory Medicine, Memorial Sloan-Kettering Cancer Center (MSKCC), United States; The Department of Pathology, Weill-Cornell Medical College, NY, NY 10065, United States
| | - Kinga K Hosszu
- The Departments of Medicine, Stony Brook University, Stony Brook, NY 11794, United States
| | - Mahalakshmi Ramadass
- The Departments of Pathology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Richard R Kew
- The Departments of Pathology, Stony Brook University, Stony Brook, NY 11794, United States
| | - Uday Kishore
- Center for Infection, Immunity and Disease Mechanisms, Biosciences, Brunel University, Uxbridge, UB8 3PH London, UK
| | - Ellinor I B Peerschke
- The Department of Laboratory Medicine, Memorial Sloan-Kettering Cancer Center (MSKCC), United States; The Department of Pathology, Weill-Cornell Medical College, NY, NY 10065, United States
| | - Berhane Ghebrehiwet
- The Departments of Medicine, Stony Brook University, Stony Brook, NY 11794, United States; The Departments of Pathology, Stony Brook University, Stony Brook, NY 11794, United States.
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Chikazawa M, Shibata T, Hatasa Y, Hirose S, Otaki N, Nakashima F, Ito M, Machida S, Maruyama S, Uchida K. Identification of C1q as a Binding Protein for Advanced Glycation End Products. Biochemistry 2016; 55:435-46. [PMID: 26731343 DOI: 10.1021/acs.biochem.5b00777] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Advanced glycation end products (AGEs) make up a heterogeneous group of molecules formed from the nonenzymatic reaction of reducing sugars with the free amino groups of proteins. The abundance of AGEs in a variety of age-related diseases, including diabetic complications and atherosclerosis, and their pathophysiological effects suggest the existence of innate defense mechanisms. Here we examined the presence of serum proteins that are capable of binding glycated bovine serum albumin (AGEs-BSA), prepared upon incubation of BSA with dehydroascorbate, and identified complement component C1q subcomponent subunit A as a novel AGE-binding protein in human serum. A molecular interaction analysis showed the specific binding of C1q to the AGEs-BSA. In addition, we identified DNA-binding regions of C1q, including a collagen-like domain, as the AGE-binding site and established that the amount of positive charge on the binding site was the determining factor. C1q indeed recognized several other modified proteins, including acylated proteins, suggesting that the binding specificity of C1q might be ascribed, at least in part, to the electronegative potential of the ligand proteins. We also observed that C1q was involved in the AGEs-BSA-activated deposition of complement proteins, C3b and C4b. In addition, the AGEs-BSA mediated the proteolytic cleavage of complement protein 5 to release C5a. These findings provide the first evidence of AGEs as a new ligand recognized by C1q, stimulating the C1q-dependent classical complement pathway.
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Affiliation(s)
- Miho Chikazawa
- Graduate School of Bioagricultural Sciences, Nagoya University , Nagoya 464-8601, Japan
| | - Takahiro Shibata
- Graduate School of Bioagricultural Sciences, Nagoya University , Nagoya 464-8601, Japan.,PRESTO, Japan Science and Technology Agency (JST) , Kawaguchi, Saitama 332-0012, Japan
| | - Yukinori Hatasa
- Graduate School of Bioagricultural Sciences, Nagoya University , Nagoya 464-8601, Japan
| | - Sayumi Hirose
- Graduate School of Bioagricultural Sciences, Nagoya University , Nagoya 464-8601, Japan
| | - Natsuki Otaki
- Graduate School of Bioagricultural Sciences, Nagoya University , Nagoya 464-8601, Japan
| | - Fumie Nakashima
- Graduate School of Bioagricultural Sciences, Nagoya University , Nagoya 464-8601, Japan
| | - Mika Ito
- Graduate School of Bioagricultural Sciences, Nagoya University , Nagoya 464-8601, Japan
| | - Sachiko Machida
- National Food Research Institute , 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan
| | - Shoichi Maruyama
- Department of Nephrology, Graduate School of Medical Sciences, Nagoya University , Nagoya 464-8601, Japan
| | - Koji Uchida
- Graduate School of Bioagricultural Sciences, Nagoya University , Nagoya 464-8601, Japan
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Hwang SD, Bae JS, Jo DH, Kim KI, Cho MY, Jee BY, Park MA, Park CI. Gene expression and functional characterization of serum amyloid P component 2 in rock bream, Oplegnathus fasciatus. FISH & SHELLFISH IMMUNOLOGY 2015; 47:521-527. [PMID: 26455663 DOI: 10.1016/j.fsi.2015.09.048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 09/21/2015] [Accepted: 09/29/2015] [Indexed: 06/05/2023]
Abstract
Mammalian serum amyloid P component (SAP) recognizes a wide range of exogenous pathogenic substances and activates a complementary pathway leading to pathogen clearance. To determine the potential roles of SAP in the fish immune system, SAP (RbSAP2) gene was cloned from ESTs analysis of rock bream (Oplegnathus fasciatus), which consisted of a signal peptide and pentraxin domain. Phylogenetic analysis revealed that the RbSAP2 gene was classified with other known fish SAPs. RbSAP2 was highly expressed in the liver of healthy rock bream. Overall, pathogen exposure led to an induction of RbSAP2 in the liver and spleen, although this effect was not observed in the spleen following infection with Edwardsiella tarda. A high concentration of recombinant RbSAP2 (rRbSAP2) showed lower growth Streptococcus iniae than control in the absence of Ca(2+), whereas E. tarda growth was decreased by high concentration of rRbSAP in the presence of the Ca(2+). These results suggest that RbSAP plays an important role in the immune response against invading pathogens.
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Affiliation(s)
- Seong Don Hwang
- Aquatic Life Disease Control Division, National Fisheries Research & Development Institute, 216 Gijanghaean-Ro, Gijang-Eup, Gijang-Gun, Busan, 619-705, Republic of Korea
| | - Jin-Sol Bae
- Department of Marine Biology and Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 38 Cheondaegukchi-Gil, Tongyeong, Gyeongnam 650-160, Republic of Korea
| | - Dong Hee Jo
- Department of Marine Biology and Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 38 Cheondaegukchi-Gil, Tongyeong, Gyeongnam 650-160, Republic of Korea
| | - Kwang Il Kim
- Aquaculture Industry Division, East Sea Fisheries Research Institute, National Fisheries Research & Development Institute, 482 Sacheonhaean-Ro Yeongok-Myeon, Gangneung, Gangwon, 210-861, Republic of Korea
| | - Mi Young Cho
- Aquatic Life Disease Control Division, National Fisheries Research & Development Institute, 216 Gijanghaean-Ro, Gijang-Eup, Gijang-Gun, Busan, 619-705, Republic of Korea
| | - Bo Young Jee
- Aquatic Life Disease Control Division, National Fisheries Research & Development Institute, 216 Gijanghaean-Ro, Gijang-Eup, Gijang-Gun, Busan, 619-705, Republic of Korea
| | - Myoung-Ae Park
- Aquatic Life Disease Control Division, National Fisheries Research & Development Institute, 216 Gijanghaean-Ro, Gijang-Eup, Gijang-Gun, Busan, 619-705, Republic of Korea
| | - Chan-Il Park
- Department of Marine Biology and Aquaculture, Institute of Marine Industry, College of Marine Science, Gyeongsang National University, 38 Cheondaegukchi-Gil, Tongyeong, Gyeongnam 650-160, Republic of Korea.
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15
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Mediation of a non-proteolytic activation of complement component C3 by phospholipid vesicles. Biomaterials 2014; 35:3688-96. [DOI: 10.1016/j.biomaterials.2013.12.085] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 12/22/2013] [Indexed: 11/21/2022]
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16
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Du Clos TW. Pentraxins: structure, function, and role in inflammation. ISRN INFLAMMATION 2013; 2013:379040. [PMID: 24167754 PMCID: PMC3791837 DOI: 10.1155/2013/379040] [Citation(s) in RCA: 152] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 08/19/2013] [Indexed: 12/03/2022]
Abstract
The pentraxins are an ancient family of proteins with a unique architecture found as far back in evolution as the Horseshoe crab. In humans the two members of this family are C-reactive protein and serum amyloid P. Pentraxins are defined by their sequence homology, their pentameric structure and their calcium-dependent binding to their ligands. Pentraxins function as soluble pattern recognition molecules and one of the earliest and most important roles for these proteins is host defense primarily against pathogenic bacteria. They function as opsonins for pathogens through activation of the complement pathway and through binding to Fc gamma receptors. Pentraxins also recognize membrane phospholipids and nuclear components exposed on or released by damaged cells. CRP has a specific interaction with small nuclear ribonucleoproteins whereas SAP is a major recognition molecule for DNA, two nuclear autoantigens. Studies in autoimmune and inflammatory disease models suggest that pentraxins interact with macrophage Fc receptors to regulate the inflammatory response. Because CRP is a strong acute phase reactant it is widely used as a marker of inflammation and infection.
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Affiliation(s)
- Terry W. Du Clos
- The Department of Veterans Affairs Medical Center, Research Service 151, 1501 San Pedro SE, Albuquerque, NM 87108, USA
- Department of Internal Medicine, The University of New Mexico School of Medicine, Albuquerque, NM 87108, USA
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17
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Vanhecke D, Roumenina LT, Wan H, Osthoff M, Schaller M, Trendelenburg M. Identification of a major linear C1q epitope allows detection of systemic lupus erythematosus anti-C1q antibodies by a specific peptide-based enzyme-linked immunosorbent assay. ACTA ACUST UNITED AC 2013; 64:3706-14. [PMID: 22740328 DOI: 10.1002/art.34605] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Autoantibodies against C1q strongly correlate with the occurrence of severe nephritis in patients with systemic lupus erythematosus (SLE). We undertook this study to determine whether identification of the C1q epitope(s) recognized by these autoantibodies might lead to a better diagnostic assay and help elucidate the putative role of C1q and anti-C1q in SLE. METHODS SLE patient-derived anti-C1q Fab were used in a microarray-based peptide scan to identify the peptide sequence recognized by anti-C1q. Anti-C1q Fab binding to the target peptide was further analyzed using real-time interaction measurements (surface plasmon resonance) and peptide-based enzyme-linked immunosorbent assays (ELISAs). RESULTS A peptide scan of the collagen-like region of C1q identified 2 regions, 1 on the A chain and 1 on the B chain, that were the targets of the anti-C1q Fab. Binding was confirmed by surface plasmon resonance and showed nanomolar affinity. The A chain-derived peptide could specifically be detected in a peptide-based ELISA by SLE patient sera. Competition experiments suggested that this peptide represented one of the major linear epitopes of C1q that is the target of anti-C1q in SLE. Serum antibodies from most SLE patients but not from healthy individuals specifically bound to this epitope. Binding to the peptide correlated with binding of the same sera to native C1q but was found to be more sensitive for the detection of lupus nephritis. CONCLUSION We identified a major linear epitope of C1q that is the target of anti-C1q in SLE. The ELISA using this peptide was more specific and more sensitive than a conventional anti-C1q assay for the detection of active nephritis in SLE patients.
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18
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Li Y, Robins JH, Ye J, Huang Z, Wen Q, Zhang G. Adaptive diversity of innate immune receptor family short pentraxins in Murinae. FEBS Lett 2012; 586:798-803. [PMID: 22306119 DOI: 10.1016/j.febslet.2012.01.048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 01/20/2012] [Accepted: 01/23/2012] [Indexed: 10/14/2022]
Abstract
The short pentraxins C-reactive protein (CRP) and serum amyloid P component (SAP) constitute a group of innate immune receptors that trigger immune activation by detecting molecules of the microbial cell wall. Here, we examined the evolution of short pentraxins in Murinae lineages. By molecular evolutionary analysis, CRP and SAP have been experiencing rapid diversification, driven by adaptive selection. Further, our protein modeling demonstrates that adaptively selected amino acids lie in the ligand-binding region and contact region between subunits. Our findings suggest that rapid diversification of these regions could contribute to the determinants of recognizing specificity and the interaction between subunits.
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Affiliation(s)
- Yan Li
- College of Animal Science and Technology, Sichuan Agriculture University, Yaan, Sichuan, PR China.
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19
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Abstract
The complement system is an important part of innate immunity; however, as with other parts of the immune system, the complement system can become pathologically activated and create or worsen disease. Anticomplement reagents have been studied for several years, but only recently have they emerged as a viable therapeutic tool. Here, we describe the role of the complement system in a wide array of diseases, as well as the use of anticomplement therapy as treatment for these diseases in animal models and in human clinical trials. Specifically, we will discuss the role of anticomplement therapy in paroxysmal nocturnal hemoglobinuria, glomerulonephritis, and heart disease, including coronary artery disease, myocardial infarction, and coronary revascularization procedures such as percutaneous coronary angioplasty and coronary artery bypass graft surgery.
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20
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Fay WP. Linking inflammation and thrombosis: Role of C-reactive protein. World J Cardiol 2010; 2:365-9. [PMID: 21179303 PMCID: PMC3006472 DOI: 10.4330/wjc.v2.i11.365] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 09/18/2010] [Accepted: 09/23/2010] [Indexed: 02/06/2023] Open
Abstract
C-reactive protein (CRP) is a biomarker of inflammation. Increased plasma levels of CRP are associated with an increased risk of myocardial infarction. However, the correlation between plasma CRP concentration and atherosclerotic plaque burden is poor. Based on these observations, it has been hypothesized that CRP increases the risk of myocardial infarction by promoting thrombosis. This article reviews available data that link enhanced CRP expression to increased risk of thrombosis, with a focus on the effects of CRP on hemostasis, platelet function, and fibrinolysis. Overall, the available data support the hypothesis that CRP is an important mechanistic link between inflammation and thrombosis.
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Affiliation(s)
- William P Fay
- William P Fay, Department of Internal Medicine and Medical Pharmacology and Physiology, University of Missouri, School of Medicine, and the Research Service, Harry S. Truman Memorial Veterans Affairs Hospital, Columbia, MO 65212, United States
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21
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Silver KL, Higgins SJ, McDonald CR, Kain KC. Complement driven innate immune response to malaria: fuelling severe malarial diseases. Cell Microbiol 2010; 12:1036-45. [PMID: 20545944 DOI: 10.1111/j.1462-5822.2010.01492.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Severe malaria remains a major cause of global mortality. The innate immune response to infection is a key determinant of malaria severity and outcome. The complement system plays a key role in initiating and augmenting innate immune responses, including inflammation, endothelial activation, opsonization and coagulation, processes which have been implicated in malaria pathogenesis. In this review, we discuss the evidence supporting a role for excessive complement activation in the pathogenesis of severe malaria.
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Affiliation(s)
- Karlee L Silver
- McLaughlin-Rotman Centre for Global Health, University Health Network-Toronto General Hospital, University of Toronto, Toronto, ON, Canada
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22
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Duvall MR, Hwang HY, Boackle RJ. Specific inhibition of the classical complement pathway with an engineered single-chain Fv to C1q globular heads decreases complement activation by apoptotic cells. Immunobiology 2009; 215:395-405. [PMID: 19586684 DOI: 10.1016/j.imbio.2009.05.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 05/26/2009] [Accepted: 05/30/2009] [Indexed: 11/28/2022]
Abstract
Apoptotic cells are potent complement activators; and proposed mechanisms include IgM-mediated classical pathway activation, C-reactive protein (CRP)-mediated classical pathway activation, and IgM-mediated lectin pathway activation. While complement activation is beneficial in clearing apoptotic cells, the resulting complement-mediated inflammation may extend damage to the surrounding cells and tissues, as observed in ischemia/reperfusion injury. We previously engineered and characterized a single-chain Fv against C1q globular heads (scFv(QuVHVL)) that blocked C1q binding to immobilized IgG and to IgG-sensitized cells, and thereby inhibited IgG-mediated classical pathway activation [Hwang H.Y., Duvall M.R., Tomlinson S., Boackle R.J., 2008. Highly specific inhibition of C1q globular-head binding to human IgG: a novel approach to control and regulate the classical complement pathway using an engineered single-chain antibody variable fragment. Molecular Immunology 45, 2570-2580]. In the present study, this scFv(QuVHVL) was examined for its ability to restrict complement deposition on apoptotic cells in the presence of fresh normal human serum (NHS). Interestingly, the addition of scFv(QuVHVL) to NHS decreased C1-mediated C4b deposition on apoptotic cells by 60% as compared to appropriate buffer-treated control serum. By inhibiting initiation of the early complement components, the subsequent C3b and membrane attack complex depositions were inhibited by 70%. Apoptotic cells may acquire serum CRP, a known classical complement pathway activator. It was observed that scFv(QuVHVL) blocked C1 binding to CRP and blocked CRP-mediated classical pathway activation using an ELISA format. However, under the experimental conditions used, the addition of exogenous CRP to apoptotic cells did not further increase the levels of C4b, C3b, or MAC deposition significantly, suggesting predominance by other activation mechanisms, such as antibody-C1-mediated complement activation. In summary, the results indicated that C1-mediated classical pathway activation was a highly significant mechanism for complement activation by apoptotic cells. In the future, specific inhibition of classical complement pathway activation by a humanized form of scFv(QuVHVL) may be useful in reducing inadvertent damage to healthy bystander tissue in a variety of acute, complement-mediated inflammatory conditions, including ischemia/reperfusion injury.
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Affiliation(s)
- Marcus R Duvall
- Department of Microbiology and Immunology, Medical University of South Carolina, 171 Ashley Avenue, Charleston, SC 29464, USA
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Deban L, Bottazzi B, Garlanda C, de la Torre YM, Mantovani A. Pentraxins: multifunctional proteins at the interface of innate immunity and inflammation. Biofactors 2009; 35:138-45. [PMID: 19449441 DOI: 10.1002/biof.21] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Pentraxins are a family of multimeric pattern recognition proteins highly conserved in evolution. On the basis of the primary structure of the protomer, pentraxins are divided into two groups: short pentraxins and long pentraxins. C reactive protein, the first pattern recognition receptor identified, and serum amyloid P component are classic short pentraxins produced in the liver in response to IL-6. Long pentraxins, including the prototype PTX3, are expressed in a variety of tissues. PTX3 is produced by a variety of cells and tissues, most notably dendritic cells and macrophages, in response to Toll-like receptor (TLR) engagement and inflammatory cytokines. Through interaction with several ligands, including selected pathogens and apoptotic cells, pentraxins play a role in complement activation, pathogen recognition and apoptotic cell clearance. In addition, PTX3 is involved in the deposition of extracellular matrix and female fertility. Unlike the classic short pentraxins CRP and SAP, PTX3 primary sequence and regulation are highly conserved in man and mouse. Thus, gene targeting identified PTX3 (and presumably other members of the family) as multifunctional soluble pattern recognition receptors acting as a nonredundant component of the humoral arm of innate immunity and involved in tuning inflammation, matrix deposition, and female fertility. (c) 2009 International Union of Biochemistry and Molecular Biology, Inc.
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Affiliation(s)
- Livija Deban
- Laboratory for Immunology and Inflammation, Istituto Clinico Humanitas IRCCS, Rozzano, Milan, Italy
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24
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Trouw LA, Okroj M, Kupreishvili K, Landberg G, Johansson B, Niessen HWM, Blom AM. C4b-binding protein is present in affected areas of myocardial infarction during the acute inflammatory phase and covers a larger area than C3. PLoS One 2008; 3:e2886. [PMID: 18682851 PMCID: PMC2483938 DOI: 10.1371/journal.pone.0002886] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 07/16/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND During myocardial infarction reduced blood flow in the heart muscle results in cell death. These dying/dead cells have been reported to bind several plasma proteins such as IgM and C-reactive protein (CRP). In the present study we investigated whether fluid-phase complement inhibitor C4b-binding protein (C4BP) would also bind to the infarcted heart tissue. METHODS AND FINDINGS Initial studies using immunohistochemistry on tissue arrays for several cardiovascular disorders indicated that C4BP can be found in heart tissue in several cardiac diseases but that it is most abundantly found in acute myocardial infarction (AMI). This condition was studied in more detail by analyzing the time window and extent of C4BP positivity. The binding of C4BP correlates to the same locations as C3b, a marker known to correlate to the patterns of IgM and CRP staining. Based on criteria that describe the time after infarction we were able to pinpoint that C4BP binding is a relatively early marker of tissue damage in myocardial infarction with a peak of binding between 12 hours and 5 days subsequent to AMI, the phase in which infiltration of neutrophilic granulocytes in the heart is the most extensive. CONCLUSIONS C4BP, an important fluid-phase inhibitor of the classical and lectin pathway of complement activation binds to jeopardized cardiomyocytes early after AMI and co-localizes to other well known markers such as C3b.
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Affiliation(s)
- Leendert A. Trouw
- Department of Laboratory Medicine, Medical Protein Chemistry, Lund University, Malmö, Sweden
| | - Marcin Okroj
- Department of Laboratory Medicine, Medical Protein Chemistry, Lund University, Malmö, Sweden
| | - Koba Kupreishvili
- Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
| | | | - Bengt Johansson
- Department of Cardiology, Umeå University, Norrlands University Hospital, Umeå, Sweden
| | - Hans W. M. Niessen
- Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands
- Department of Pathology and Cardiac Surgery, VU University Medial Center, Amsterdam, The Netherlands
| | - Anna M. Blom
- Department of Laboratory Medicine, Medical Protein Chemistry, Lund University, Malmö, Sweden
- * E-mail:
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Roumenina LT, Popov KT, Bureeva SV, Kojouharova M, Gadjeva M, Rabheru S, Thakrar R, Kaplun A, Kishore U. Interaction of the globular domain of human C1q with Salmonella typhimurium lipopolysaccharide. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2008; 1784:1271-6. [PMID: 18513495 DOI: 10.1016/j.bbapap.2008.04.029] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 04/25/2008] [Accepted: 04/29/2008] [Indexed: 12/29/2022]
Abstract
Gram-negative bacteria can bind complement protein C1q in an antibody-independent manner and activate classical pathway via their lipopolysaccharides (LPS). Earlier studies have implicated the collagen-like region of human C1q in binding LPS. In recent years, a number of C1q target molecules, previously considered to interact with collagen-like region of C1q, have been shown to bind via the globular domain (gC1q). Here we report, using recombinant forms of the globular head regions of C1q A, B and C chains, that LPS derived from Salmonella typhimurium interact specifically with the B-chain of the gC1q domain in a calcium-dependent manner. LPS and IgG-binding sites on the gC1q domain appear to be overlapping and this interaction can be inhibited by a synthetic C1q inhibitor, suggesting common interacting mechanisms.
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Affiliation(s)
- Lubka T Roumenina
- Department of Biochemistry, Sofia University, St. Kliment Ohridski, 8 Dragan Tsankov St., Sofia 1164, Bulgaria
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26
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Development of a humanized C1q A chain knock-in mouse: assessment of antibody independent beta-amyloid induced complement activation. Mol Immunol 2008; 45:3244-52. [PMID: 18400300 DOI: 10.1016/j.molimm.2008.02.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 02/20/2008] [Accepted: 02/26/2008] [Indexed: 11/22/2022]
Abstract
Evidence has been accumulating for a role of inflammation in the development of Alzheimer's disease (AD), a progressive neurodegenerative disorder causing a common form of dementia in the elderly. C1q, part of the initiation component of the classical complement pathway (CCP), is associated with beta-sheet, fibrillar amyloid plaques in AD brain. In vitro, beta-amyloid peptide in fibrillar beta-sheet conformation (fAbeta) can activate CCP via interaction of specific negatively charged amino acids of the beta-amyloid fibril with human C1q. Previous results using peptide inhibitors led to the hypothesis that a highly positively charged domain consisting of three arginine residues, such as that present in the N-terminal collagen-like region of the human C1q A chain, may be critical for the activation event. However, mouse C1q A chain lacks two of the three arginines in the corresponding C1q A chain collagen-like region. To test the hypothesis that this divergent activation domain results in a weaker C' activation and thus may contribute to the lower neuronal loss observed in transgenic mouse models of AD, a partially humanized C1q A chain knock-in mouse was generated. The mouse C1q A chain gene was modified by homologous recombination to replace 4 residues in the 13-20 amino acid region to mimic the corresponding sequence from human A chain. No significant differences in the expression of C1q were found in sera from mice homozygous for the humanized C1q A chain compared to littermate wild type mice. Two distinct C1 activation assays demonstrated that activation by fAbeta was not significantly different in the homozygous humanized C1q A chain mice. Activation of C1 by DNA, previously hypothesized to interact with this C1q A chain arginine-rich sequence was also not significantly different in the knock-in mouse. Molecular modeling based on the published crystal structure of human C1q B chain globular head and a beta-sheet model for fibrillar amyloid suggests an alternative arginine ladder in the globular head domain may provide the functional C1 activating interaction domains. The humanized C1q mouse generated here should provide a better animal model for assessing the mechanisms of C1 activation and the contribution of C1q to human health and disease.
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27
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Trouw LA, Bengtsson AA, Gelderman KA, Dahlbäck B, Sturfelt G, Blom AM. C4b-binding Protein and Factor H Compensate for the Loss of Membrane-bound Complement Inhibitors to Protect Apoptotic Cells against Excessive Complement Attack. J Biol Chem 2007; 282:28540-28548. [PMID: 17699521 DOI: 10.1074/jbc.m704354200] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Apoptotic cells have been reported to down-regulate membrane-bound complement regulatory proteins (m-C-Reg) and to activate complement. Nonetheless, most apoptotic cells do not undergo complement-mediated lysis. Therefore, we hypothesized that fluid phase complement inhibitors would bind to apoptotic cells and compensate functionally for the loss of m-C-Reg. We observed that m-C-Reg are down-regulated rapidly upon apoptosis but that complement activation follows only after a gap of several hours. Coinciding with, but independent from, complement activation, fluid phase complement inhibitors C4b-binding protein (C4BP) and factor H (fH) bind to the cells. C4BP and fH do not entirely prevent complement activation but strongly limit C3 and C9 deposition. Late apoptotic cells, present in blood of healthy controls and systemic lupus erythematosus patients, are also positive for C4BP and fH. Upon culture, the percentage of late apoptotic cells increases, paralleled by increased C4BP binding. C4BP binds to dead cells mainly via phosphatidylserine, whereas fH binds via multiple interactions with CRP playing no major role for binding of C4BP or fH. In conclusion, during late apoptosis, cells acquire fluid phase complement inhibitors that compensate for the down-regulation of m-C-Reg and protect against excessive complement activation and lysis.
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Affiliation(s)
- Leendert A Trouw
- Department of Laboratory Medicine, University Hospital Malmö, 5-20502 Malmö, Sweden
| | - Anders A Bengtsson
- Department of Clinical Science, Rheumatology, Lund University, 5-22184 Lund, Sweden
| | - Kyra A Gelderman
- Unit for Medical Inflammation Research, Lund University, 5-22184 Lund, Sweden
| | - Björn Dahlbäck
- Department of Laboratory Medicine, University Hospital Malmö, 5-20502 Malmö, Sweden
| | - Gunnar Sturfelt
- Department of Clinical Science, Rheumatology, Lund University, 5-22184 Lund, Sweden
| | - Anna M Blom
- Department of Laboratory Medicine, University Hospital Malmö, 5-20502 Malmö, Sweden.
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28
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Bureeva S, Andia-Pravdivy J, Symon A, Bichucher A, Moskaleva V, Popenko V, Shpak A, Shvets V, Kozlov L, Kaplun A. Selective inhibition of the interaction of C1q with immunoglobulins and the classical pathway of complement activation by steroids and triterpenoids sulfates. Bioorg Med Chem 2007; 15:3489-98. [PMID: 17383882 DOI: 10.1016/j.bmc.2007.03.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2006] [Revised: 02/17/2007] [Accepted: 03/02/2007] [Indexed: 11/30/2022]
Abstract
Since undesirable activation of the complement system through the classical pathway is associated with tissue damage and other pathologic proinflammatory consequences at ischemia/reperfusion injury, autoimmune diseases, and rejection of allo- and xenografts, creation of selective inhibitors of the classical pathway leaving the alternative pathway intact is of great importance. Classical pathway is triggered by binding of its recognizing unit, protein C1q, to a number of targets like antibodies, pentraxins, apoptotic cells, and others. In order to obtain inhibitors blocking the first step of the classical cascade, synthesis of sulfates of steroids (Delta(5)-3beta-hydroxycholenic, Delta(5)-3beta-hydroxyetiocholenic, deoxycholic, and cholic acids) and triterpenoids (betulin, 20,29-dihydro-20,29-dichloromethylenbetulin, betulinic, ursolic, and oleanolic acids) has been performed. Testing of the compounds in classical pathway inhibition assay has displayed derivatives of triterpenoid betulin (betulin disulfate and betulinic acid sulfate) to be the most potent inhibitors. Further studies of the two compounds established that their activity to inhibit the classical pathway had been due to their capability to block the interaction of C1q with antibodies. Betulin disulfate and betulinic acid sulfate have shown weak inhibition of the alternative route of activation, what makes them promising inhibitors for the selective suppression of the classical complement pathway at the earliest possible level as well as perspective agents for blocking the interaction of C1q with its other targets.
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Affiliation(s)
- Svetlana Bureeva
- M.V. Lomonosov State Academy of Fine Chemical Technology, Biotechnology Department, Vernadskogo str., 86, 119571 Moscow, Russia.
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29
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Rhodes DCJ. Importance of carbohydrate in the interaction of Tamm‐Horsfall protein with complement 1q and inhibition of classical complement activation. Immunol Cell Biol 2006; 84:357-65. [PMID: 16594900 DOI: 10.1111/j.1440-1711.2006.01434.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tamm-Horsfall protein (THP) binds strongly to complement 1q (C1q), a key component of the classical complement pathway. The goals of this study were to determine whether THP altered the activation of the classical complement pathway and whether the carbohydrate portion of THP was involved in this glycoprotein's binding to C1q and alteration of complement activation. The ability of THP to prevent complement activation in diluted serum or plasma incubated at 37 degrees C was assessed using both a haemolytic assay with antibody-sensitized sheep RBC and a C4d ELISA. Both these methods showed that THP inhibited activation of the classical complement pathway in a dose-dependent manner. Glycosidases were used to remove most of the carbohydrate from THP. This partially deglycosylated THP bound human IgG with a higher affinity (KD1 = 1.4 nmol/L; KD2 = 0.31 micromol/L) than did intact THP (KD1 = 33.4 nmol/L; KD2 = 31.0 micromol/L). An ELISA showed that removal of carbohydrate from THP reduced, but did not eliminate, the ability of this protein to inhibit binding of C1q to intact THP. Haemolysis assays using antibody-sensitized sheep RBC showed that removal of THP carbohydrate eliminated the ability of THP to protect against complement activation. In conclusion, THP inhibited the activation of the classical complement pathway that occurred in diluted serum or plasma. The carbohydrate moieties of THP appeared to be important in this inhibitory activity.
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Affiliation(s)
- Diana C J Rhodes
- Department of Anatomy, A.T. Still University of Health Sciences, Kirksville College of Osteopathic Medicine, Kirksville, Missouri 63501, USA.
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30
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McGrath FDG, Brouwer MC, Arlaud GJ, Daha MR, Hack CE, Roos A. Evidence That Complement Protein C1q Interacts with C-Reactive Protein through Its Globular Head Region. THE JOURNAL OF IMMUNOLOGY 2006; 176:2950-7. [PMID: 16493053 DOI: 10.4049/jimmunol.176.5.2950] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
C1q acts as the recognition unit of the first complement component, C1, and binds to immunoglobulins IgG and IgM, as well as to non-Ig ligands, such as C-reactive protein (CRP). IgG and IgM are recognized via the globular head regions of C1q (C1qGR), whereas CRP has been postulated to interact with the collagen-like region (C1qCLR). In the present study, we used a series of nine mAbs to C1q, five directed against C1qGR and four against C1qCLR, to inhibit the interaction of C1q with CRP. The F(ab')(2) of each of the five mAbs directed against C1qGR inhibited binding of C1q to polymerized IgG. These five mAbs also successfully inhibited the interaction of C1q with CRP. Moreover, these five mAbs inhibited C1 activation by CRP as well as by polymerized IgG in vitro. In contrast, none of the four mAbs against C1qCLR inhibited C1q interaction with CRP or IgG, or could reduce activation of complement by CRP or polymerized IgG. These results provide the first evidence that the interaction of C1q with CRP or IgG involves sites located in the C1qGR, whereas sites in the CLR do not seem to be involved in the physiological interaction of C1q with CRP.
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Affiliation(s)
- Fabian D G McGrath
- Department of Immunopathology, Sanquin Research, Amsterdam, The Netherlands
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31
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Garlanda C, Bottazzi B, Bastone A, Mantovani A. Pentraxins at the crossroads between innate immunity, inflammation, matrix deposition, and female fertility. Annu Rev Immunol 2005; 23:337-66. [PMID: 15771574 DOI: 10.1146/annurev.immunol.23.021704.115756] [Citation(s) in RCA: 641] [Impact Index Per Article: 33.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
C reactive protein, the first innate immunity receptor identified, and serum amyloid P component are classic short pentraxins produced in the liver. Long pentraxins, including the prototype PTX3, are expressed in a variety of tissues. Some long pentraxins are expressed in the brain and some are involved in neuronal plasticity and degeneration. PTX3 is produced by a variety of cells and tissues, most notably dendritic cells and macrophages, in response to Toll-like receptor (TLR) engagement and inflammatory cytokines. PTX3 acts as a functional ancestor of antibodies, recognizing microbes, activating complement, and facilitating pathogen recognition by phagocytes, hence playing a nonredundant role in resistance against selected pathogens. In addition, PTX3 is essential in female fertility because it acts as a nodal point for the assembly of the cumulus oophorus hyaluronan-rich extracellular matrix. Thus, the prototypic long pentraxin PTX3 is a multifunctional soluble pattern recognition receptor at the crossroads between innate immunity, inflammation, matrix deposition, and female fertility.
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Affiliation(s)
- Cecilia Garlanda
- Istituto di Ricerche Farmacologiche Mario Negri, 20157 Milan, Italy.
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32
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Tissot B, Gonnet F, Iborra A, Berthou C, Thielens N, Arlaud GJ, Daniel R. Mass spectrometry analysis of the oligomeric C1q protein reveals the B chain as the target of trypsin cleavage and interaction with fucoidan. Biochemistry 2005; 44:2602-9. [PMID: 15709773 DOI: 10.1021/bi047802h] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
C1q is a subunit of the C1 complex that triggers activation of the complement classical pathway through recognition and binding of immune complexes. C1q also binds to nonimmune ligands such as the sulfated polysaccharide fucoidan, a potent anticomplementary agent. C1q was submitted for the first time to mass spectrometry analysis, yielding insights into its assembly and its interaction with fucoidan. The MALDI-TOF mass spectrometry technique on membrane allowed partial preservation of noncovalent interactions, allowing precise analysis of its substructure and estimation of the C1q molecular weight at 459520-461883, with an average mass of 460793 g x mol(-1). The disulfide-linked A-B and C-C dimers as well as the noncovalent structural unit (A-B:C)-(C:B-A) were detected, providing experimental support to the C1q model based on covalent and noncovalent associations of six heterotrimers. Trypsin treatment of native C1q led to proteolysis of the B chain only, at a single cleavage site (Arg(109)) located in the globular region. Unlike DNA, fucoidan protected C1q from trypsin cleavage, indicating that this polysaccharide binds to the B moiety of the globular head. Given the involvement of the C1q globular heads in the recognition of IgG, this interaction may account for the observed anticomplementary activity of fucoidan.
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Affiliation(s)
- Bérangère Tissot
- Laboratoire de Thérapie Cellulaire, CHU Morvan, 5 Avenue Foch, 29200 Brest, France
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33
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Mantovani A, Garlanda C, Otero K, Peri G, Vecchi A, Bottazzi B. Membrane and soluble pattern recognition receptors: the unique functions of the long pentraxin PTX3. ACTA ACUST UNITED AC 2004. [DOI: 10.1111/j.1472-9725.2004.00048.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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34
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Thordardottir S, Traustadottir KH, Erlendsson K. A discrepancy between liquid phase and gel phase assays for evaluation of total complement activity and some possible explanations. Scand J Immunol 2004; 59:574-81. [PMID: 15182253 DOI: 10.1111/j.0300-9475.2004.01438.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
This study was conducted to investigate the frequency and origin of discrepant assay results between two haemolytic assays which both measure activity of the classical pathway of complement (CH50) by haemolysis of sheep red blood cells (SRBCs). One is conducted in gel phase using undiluted sera and the other in liquid phase with sera in 1/100 dilution. The majority of discrepant readings are observed as low or absent haemolysis in the gel phase, with values within or above the normal range in the liquid phase. The incidence of discrepant assay readings was evaluated in 300 samples. Furthermore, 28 samples showing the most discrepant readings were investigated further for disturbing factors. Factors evaluated in the test sera were mannose-binding lectin, C-reactive protein (CRP), immune complexes, antibodies to SRBCs, rheumatoid factor and immunoglobulin A (IgA) and IgG anti-C1q antibodies. The results showed that discrepant readings are present in 10% of the 300 samples and false low gel assay readings account for 6.3%. The majority (68%) of the discrepant samples contained a heat-stable-inhibiting factor, and the main mediators found were elevated levels of IgA anti-C1q antibodies and antibodies to SRBCs. This could indicate a clinically relevant factor in the test sera but can also result from the difference in assay design.
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Affiliation(s)
- S Thordardottir
- Department of Immunology, Landspitali University Hospital, Reykjavik, Iceland
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35
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Tissot B, Daniel R, Place C. Interaction of the C1 complex of complement with sulfated polysaccharide and DNA probed by single molecule fluorescence microscopy. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:4714-20. [PMID: 14622259 DOI: 10.1046/j.1432-1033.2003.03870.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The complex C1 triggers the activation of the Complement classical pathway through the recognition and binding of antigen-antibody complex by its subunit C1q. The globular region of C1q is responsible for C1 binding to the immune complex. C1q can also bind nonimmune molecules such as DNA and sulfated polysaccharides, leading either to the activation or inhibition of Complement. The binding site of these nonimmune ligands is debated in the literature, and it has been proposed to be located either in the globular region or in the collagen-like region of C1q, or in both. Using single molecule fluorescence microscopy and DNA molecular combing as reporters of interactions, we have probed the C1q binding properties of T4 DNA and of fucoidan, an algal sulfated fucose-based polysaccharide endowed with potent anticomplementary activity. We have been able to visualize the binding of C1q as well as of C1 and of the isolated collagen-like region to individual DNA strands, indicating that the collagen-like region is the main binding site of DNA. From binding assays with C1r, one of the protease components of C1, we concluded that the DNA binding site on the collagen-like region is located within the stalk part. Competition experiments between fucoidan and DNA for the binding of C1q showed that fucoidan binds also to the collagen-like region part of C1q. Unlike DNA, the binding of fucoidan to collagen-like region involves interactions with the hinge region that accommodate the catalytic tetramer C1r2-C1s2 of C1. This binding property of fucoidan to C1q provides a mechanistic basis for the anticomplementary activity of the sulfated polysaccharide.
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36
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Tissot B, Montdargent B, Chevolot L, Varenne A, Descroix S, Gareil P, Daniel R. Interaction of fucoidan with the proteins of the complement classical pathway. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1651:5-16. [PMID: 14499584 DOI: 10.1016/s1570-9639(03)00230-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Fucoidan inhibits complement by mechanisms that so far remain to be unraveled, and the objective of this work was to delineate the mode of inhibition by this sulfated polysaccharide. For that purpose, low molecular weight fractions of algal (Ascophyllum nodosum) fucoidan containing the disaccharide unit [-->3)-alpha-L-Fuc(2SO3(-))-(1-->4)-alpha-L-Fuc(2,3diSO3(-))-(1-->](n) have been studied. Gel co-affinity electrophoresis and a new affinity capillary electrophoresis (ACE) method have been implemented to characterize fucoidan-complement protein complexes. Fucoidan binds C1q, likely to its collagen-like region through interactions involving lysine residues, and then prevents the association of the C1r(2)-C1s(2) subunit, required to form the fully active C1. In addition to C1q, fucoidan forms a complex with the protein C4 as observed by ACE. The fucoidan inhibits the first steps of the classical pathway activation that is of relevance in view of the proinflammatory effects of the subsequent products of the cascade. This study shows that a high level of inhibitory activity can be achieved with low molecular weight carbohydrate molecules and that the potential applicability of fucoidan oligosaccharides for therapeutic complement inhibition is worthy of consideration.
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Affiliation(s)
- Bérangère Tissot
- Laboratoire Analyse et Environnement, Université d'Evry Val-d'Essonne, Bd. François Mitterrand, 91025 Cedex, Evry, France
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Abstract
Neuroinflammation is a characteristic of pathologically affected tissue in several neurodegenerative disorders. These changes are particularly observed in affected brain areas of Alzheimer's disease (AD) cases. They include an accumulation of large numbers of activated microglia and astrocytes as well as small numbers of T-cells, mostly adhering to postcapillary venules. Accompanying biochemical alterations include the appearance or up-regulation of numerous molecules characteristic of inflammation and free radical attack. Particularly important may be the complement proteins, acute phase reactants and inflammatory cytokines. These brain phenomena combined with epidemiological evidence of a protective effect of antiinflammatory agents suggest that such agents may have a role to play in treating the disease.
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Affiliation(s)
- Edith G McGeer
- Kinsmen Laboratory of Neurological Research, Department of Psychiatry, University of British Columbia, 2255 Wesbrook Mall, Vancouver, BC, Canada V6T 1Z3.
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38
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Mantovani A, Garlanda C, Bottazzi B. Pentraxin 3, a non-redundant soluble pattern recognition receptor involved in innate immunity. Vaccine 2003; 21 Suppl 2:S43-7. [PMID: 12763682 DOI: 10.1016/s0264-410x(03)00199-3] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Pentraxin 3 (PTX3) is the first long pentraxin identified. Long pentraxins consist of a C-terminal pentraxin domain, which has sequence similarity to C-reactive protein (CRP) and serum amyloid P (SAP) component (the classic short pentraxins), and of an unrelated N-terminal portion. PTX3 is made by diverse cell types, most prominently endothelial cells, macrophages and dendritic cells, in response to primary inflammatory signals (e.g. interleukin-1 (IL-1), tumour necrosis factor (TNF), lipopolysaccharide (LPS)). It binds diverse ligands, including microbial moieties, C1q and apoptotic cells. Evidence suggests that PTX3 plays a role in the regulation of innate resistance to pathogens, inflammatory reactions, possibly clearance of self-components and female fertility.
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Affiliation(s)
- Alberto Mantovani
- Department of Immunology and Cell Biology, Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy.
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39
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Rostagno A, Revesz T, Lashley T, Tomidokoro Y, Magnotti L, Braendgaard H, Plant G, Bojsen-Møller M, Holton J, Frangione B, Ghiso J. Complement activation in chromosome 13 dementias. Similarities with Alzheimer's disease. J Biol Chem 2002; 277:49782-90. [PMID: 12388551 DOI: 10.1074/jbc.m206448200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chromosome 13 dementias, familial British dementia (FBD) and familial Danish dementia (FDD), are associated with neurodegeneration and cerebrovascular amyloidosis, with striking neuropathological similarities to Alzheimer's disease (AD). Despite the structural differences among the amyloid subunits (ABri in FBD, ADan in FDD, and Abeta in AD), these disorders are all characterized by the presence of neurofibrillary tangles and parenchymal and vascular amyloid deposits co-localizing with markers of glial activation, suggestive of local inflammation. Proteins of the complement system and their pro-inflammatory activation products are among the inflammation markers associated with AD lesions. Immunohistochemistry of FBD and FDD brain sections demonstrated the presence of complement activation components of the classical and alternative pathways as well as the neo-epitope of the membrane attack complex. Hemolytic experiments and enzyme-linked immunosorbent assays specific for the activation products iC3b, C4d, Bb, and C5b-9 indicated that ABri and ADan are able to fully activate the complement cascade at levels comparable to those generated by Abeta1-42. ABri and ADan specifically bound C1q with high affinity and formed stable complexes in physiological conditions. Activation proceeds approximately 70-75% through the classical pathway while only approximately 25-30% seems to occur through the alternative pathway. The data suggest that the chronic inflammatory response generated by the amyloid peptides in vivo might be a contributing factor for the pathogenesis of FBD and FDD and, in more general terms, to other neurodegenerative conditions.
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Affiliation(s)
- Agueda Rostagno
- Department of Pathology, School of Medicine, New York University, 550 First Avenue, New York, NY 10016, USA.
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40
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Rhodes DCJ. Binding of Tamm-Horsfall protein to complement 1q and complement 1, including influence of hydrogen-ion concentration. Immunol Cell Biol 2002; 80:558-66. [PMID: 12406390 DOI: 10.1046/j.1440-1711.2002.01125.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The goal of this study was to further characterize the interaction between an abundant urinary glycoprotein, Tamm-Horsfall protein, and complement 1q to determine the robustness of this reaction under different environmental conditions (particularly pH) and to begin to determine the specificity of this reaction. The influence of pH coupled with ionic strength was evaluated with an ELISA that demonstrated immobilized Tamm-Horsfall protein bound complement 1q strongly with a KD in the nmol/L range from pH 9 to pH 5.5. Increasing the ionic strength from 10 mmol/L sodium chloride (NaCl) to 154 mmol/L NaCl decreased the affinity of Tamm-Horsfall protein for complement 1q slightly (2-7-fold) at pH 9 to pH 6.5. A resonant mirror biosensor was also utilized to evaluate the binding of Tamm-Horsfall protein to complement 1q at different pH values (pH 8.2-5.8). These studies indicated that, compared to at pH 8.2, Tamm-Horsfall protein bound complement 1q at pH 5.8 with an almost two-fold higher affinity (pH 8.2, KD = 5.1 nmol/L vs at pH 5.8, KD = 2.8 nmol/L) due to a faster association rate (pH 8.2 kass = 1.6 x 106 L/mol per s vs pH 5.8 kass = 2.9 x 106 L/mol per s). Surprisingly, the capacity of Tamm-Horsfall protein for complement 1q decreased significantly at pH 5.8, suggesting that a site for complement 1q binding to Tamm-Horsfall protein may be lost at the acidic pH. Biosensor studies also showed that Tamm-Horsfall protein bound the entire complement 1 complex with binding affinities and association rates similar to those obtained for complement 1q individually. This suggested that Tamm-Horsfall protein bound complement 1q at a site other than the region of its collagenous tail where C1r2 and C1s2 bind. By western blot analysis, it was demonstrated that Tamm-Horsfall protein bound preferentially to the C chain of complement 1q.
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Affiliation(s)
- Diana C J Rhodes
- Department of Anatomy, Kirksville College of Osteopathic Medicine, Missouri 63501, USA.
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41
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Abstract
Postmortem immunohistochemical studies have revealed a state of chronic inflammation limited to lesioned areas of brain in Alzheimer's disease. Some key actors in this inflammation are activated microglia (brain macrophages), proteins of the classical complement cascade, the pentraxins, cytokines, and chemokines. The inflammation does not involve the adaptive immune system or peripheral organs, but is rather due to the phylogenetically much older innate immune system, which appears to operate in most tissues of the body. Chronic inflammation can damage host tissue and the brain may be particularly vulnerable because of the postmitotic nature of neurons. Many of the inflammatory mediators have been shown to be locally produced and selectively elevated in affected regions of Alzheimer's brain. Moreover, studies of tissue in such degenerative processes as atherosclerosis and infarcted heart suggest a similar local innate immune reaction may be important in such conditions. Much epidemiological and limited clinical evidence suggests that nonsteroidal anti-inflammatory drugs may impede the onset and slow the progression of Alzheimer's disease. But these drugs strike at the periphery of the inflammatory reaction. Much better results might be obtained if drugs were found that could inhibit the activation of microglia or the complement system in brain, and combinations of drugs aimed at different inflammatory targets might be much more effective than single agents.
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Affiliation(s)
- Patrick L McGeer
- Kinsmen Laboratory of Neurological Research, Department of Psychiatry, University of British Columbia, Vancouver, British Columbia, Canada.
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42
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McGeer PL, McGeer EG. Innate immunity, local inflammation, and degenerative disease. SCIENCE OF AGING KNOWLEDGE ENVIRONMENT : SAGE KE 2002; 2002:re3. [PMID: 14602998 DOI: 10.1126/sageke.2002.29.re3] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Abstract
The brain lesions associated with Alzheimer's disease (AD), which are referred to as neurofibrillary tangles and senile plaques, are characterized by the presence of a broad spectrum of inflammatory mediators. Surprisingly, these mediators, which include complement proteins, inflammatory cytokines, prostaglandins, and acute phase reactants such as C-reactive protein and amyloid P, are produced by resident brain cells, including neurons. Although secondary to the fundamental pathology caused by the presence of tangles and plaques, there is strong evidence that inflammation exacerbates the neuronal loss. In particular, AD lesions show evidence of self-attack by the complement system--a part of the immune system that normally functions to rid the body of invading pathogens. However, the lesions are devoid of significant T cell infiltration, a hallmark of an inflammatory immune response, and antibodies. We define this phenomenon as autotoxicity to distinguish it from classical autoimmunity, in which the body raises antibodies to normal endogenous macromolecules. Locally produced inflammatory mediators have also been identified in atherosclerotic plaques, along with evidence of complement self-attack. As was previously shown for heart attacks, epidemiological evidence indicates that extended use of nonsteroidal anti-inflammatory drugs (NSAIDs) results in a reduced risk of AD. NSAIDs inhibit the production of prostaglandin inflammatory mediators, but powerful new therapeutic agents might be developed by targeting more critical inflammatory mechanisms, especially the complement system.
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Affiliation(s)
- Patrick L McGeer
- Kinsmen Laboratory of Neurological Research at the University of British Columbia, Vancouver, BC, V6T 1Z3, Canada.
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43
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Lagrand WK, Nijmeijer R, Niessen HWM, Visser CA, Hermens WT, Hack CE. C-reactive protein as a pro-inflammatory mediator in cardiovascular disease by its ability to activate complement: additional proof and hypothetical mechanisms. Neth Heart J 2002; 10:189-197. [PMID: 25696089 PMCID: PMC2499743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023] Open
Abstract
This study was financially supported by the Netherlands Heart Foundation, grant numbers 93-119 and 97-088. Dr. Niessen is a recipient of the Dr. E. Dekker programme of the Netherlands Heart Foundation (D99025).
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Agrawal A, Shrive AK, Greenhough TJ, Volanakis JE. Topology and structure of the C1q-binding site on C-reactive protein. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:3998-4004. [PMID: 11238646 DOI: 10.4049/jimmunol.166.6.3998] [Citation(s) in RCA: 127] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The host defense functions of human C-reactive protein (CRP) depend to a great extent on its ability to activate the classical complement pathway. The aim of this study was to define the topology and structure of the CRP site that binds C1q, the recognition protein of the classical pathway. We have previously reported that residue Asp(112) of CRP plays a major role in the formation of the C1q-binding site, while the neighboring Lys(114) hinders C1q binding. The three-dimensional structure of CRP shows the presence of a deep, extended cleft in each protomer on the face of the pentamer opposite that containing the phosphocholine-binding sites. Asp(112) is part of this marked cleft that is deep at its origin but becomes wider and shallower close to the inner edge of the protomer and the central pore of the pentamer. The shallow end of the pocket is bounded by the 112-114 loop, residues 86-92 (the inner loop), the C terminus of the protomer, and the C terminus of the pentraxin alpha-helix 169-176, particularly Tyr(175). Mutational analysis of residues participating in the formation of this pocket demonstrates that Asp(112) and Tyr(175) are important contact residues for C1q binding, that Glu(88) influences the conformational change in C1q necessary for complement activation, and that Asn(158) and His(38) probably contribute to the correct geometry of the binding site. Thus, it appears that the pocket at the open end of the cleft is the C1q-binding site of CRP.
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Affiliation(s)
- A Agrawal
- Division of Clinical Immunology and Rheumatology, Department of Medicine, University of Alabama, Birmingham, AL 35294, USA
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45
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McGeer PL, McGeer EG, Yasojima K. Alzheimer disease and neuroinflammation. JOURNAL OF NEURAL TRANSMISSION. SUPPLEMENTUM 2001; 59:53-7. [PMID: 10961418 DOI: 10.1007/978-3-7091-6781-6_8] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
It is now generally accepted that the lesions of Alzheimer disease (AD) are associated with a host of inflammatory molecules, including complement proteins, as well as with many activated microglia. Most inflammatory components are synthesized by brain cells. In order to estimate the intensity of the inflammatory reaction, we have measured the levels of the mRNAs for complement proteins, two complement regulators (CD59 and C1 inhibitors), an acute phase reactant (C-reactive protein, CRP) and two microglial markers, (HLA-DR and CD11b), in normal and AD brain. The mRNAs for inflammatory mediators are markedly upregulated in AD tissue while those of the complement inhibitors are almost unchanged. The upregulations for CRP and CD11b in AD hippocampus are comparable to those in osteoarthritic joints. This lends further support to the hypothesis that chronic inflammation may be causing neuronal death in AD.
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Affiliation(s)
- P L McGeer
- Department of Psychiatry, University of British Columbia, Vancouver, Canada
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46
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Abstract
C1q is the first subcomponent of the C1 complex of the classical pathway of complement activation. Several functions have been assigned to C1q, which include antibody-dependent and independent immune functions, and are considered to be mediated by C1q receptors present on the effector cell surface. There remains some uncertainty about the identities of the receptors that mediate C1q functions. Some of the previously described C1q receptor molecules, such as gC1qR and cC1qR, now appear to have less of a role in C1q functions than in functions unrelated to C1q. The problem of identifying receptor proteins with complementary binding sites for C1q has been compounded by the highly charged nature of the different domains in C1q. Although newer candidate receptors like C1qR(p) and CR1 have emerged, full analysis of the C1q-C1q receptor interactions is still at an early stage. In view of the diverse functions that C1q is considered to perform, it has been speculated that several C1q-binding proteins may act in concert, as a C1q receptor complex, to bring about C1q mediated functions. Some major advances have been made in last few years. Experiments with gene targeted homozygous C1q-deficient mice have suggested a role for C1q in modulation of the humoral immune response, and also in protection against development of autoimmunity. The recently described crystal structure of Acrp-30, which is a serum protein secreted from adipocytes, has revealed a new C1q/TNF superfamily of proteins. Although the members of this superfamily may have diverse functions, there may be a common theme in their phylogeny and modular organisation of their distinctive globular domains.
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Affiliation(s)
- U Kishore
- Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, UK
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47
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Messmer BT, Thaler DS. C1q-binding peptides share sequence similarity with C4 and induce complement activation. Mol Immunol 2000; 37:343-50. [PMID: 11074252 DOI: 10.1016/s0161-5890(00)00063-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Two peptide motifs that bind to C1q have been identified from phage displayed libraries. A first panning cycle recovered phage that displayed a [N/S]PFxL motif. A synthetic peptide with that motif blocked those phage from binding to C1q. A second panning cycle was conducted with the [N/S]PFxL motif peptide present, leading to recovery of phage displaying a different motif, SHY. The two motifs are specific for C1q and are competed by DNA and the cognate synthetic peptide but not by immunoglobulins. Phage displayed peptide sequences containing the [N/S]PFxL have significant sequence similarity to a region of complement component C4, suggesting a possible site of interaction between C4, or one of its processed forms, and C1q. The SHY motif peptide induces C4 consumption in a hemolytic assay, suggesting that it activates C1 independent of immune complexes. This peptide may activate C1 by a mechanism similar to the beta-amyloid peptides found in Alzheimer's disease.
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Affiliation(s)
- B T Messmer
- Sackler Laboratory for Molecular Genetics and Informatics, Rockefeller University, 1230 York Ave, New York, NY 10021-6399, USA.
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48
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Griselli M, Herbert J, Hutchinson W, Taylor K, Sohail M, Krausz T, Pepys M. C-reactive protein and complement are important mediators of tissue damage in acute myocardial infarction. J Exp Med 1999; 190:1733-40. [PMID: 10601349 PMCID: PMC2195725 DOI: 10.1084/jem.190.12.1733] [Citation(s) in RCA: 367] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Myocardial infarction in humans provokes an acute phase response, and C-reactive protein (CRP), the classical acute phase plasma protein, is deposited together with complement within the infarct. The peak plasma CRP value is strongly associated with postinfarct morbidity and mortality. Human CRP binds to damaged cells and activates complement, but rat CRP does not activate complement. Here we show that injection of human CRP into rats after ligation of the coronary artery reproducibly enhanced infarct size by approximately 40%. In vivo complement depletion, produced by cobra venom factor, completely abrogated this effect. Complement depletion also markedly reduced infarct size, even when initiated up to 2 h after coronary ligation. These observations demonstrate that human CRP and complement activation are major mediators of ischemic myocardial injury and identify them as therapeutic targets in coronary heart disease.
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Affiliation(s)
- M. Griselli
- Immunological Medicine Unit, Division of Medicine
- Cardiothoracic Unit, Department of Surgery
| | - J. Herbert
- Immunological Medicine Unit, Division of Medicine
| | | | | | - M. Sohail
- Department of Histopathology, Imperial College School of Medicine, Hammersmith Hospital, London W12 0NN, United Kingdom
| | - T. Krausz
- Department of Histopathology, Imperial College School of Medicine, Hammersmith Hospital, London W12 0NN, United Kingdom
| | - M.B. Pepys
- Immunological Medicine Unit, Division of Medicine
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49
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Webster SD, Tenner AJ, Poulos TL, Cribbs DH. The mouse C1q A-chain sequence alters beta-amyloid-induced complement activation. Neurobiol Aging 1999; 20:297-304. [PMID: 10588577 DOI: 10.1016/s0197-4580(99)00020-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In transgenic models of Alzheimer's disease (AD) neuronal loss has not been widely observed. The loss of neurons in AD may be due to chronic activation of complement (C') by beta-amyloid (A beta). A beta has been shown to activate C' by binding to a site on the C1q A-chain. The mouse A-chain sequence differs significantly from human, and a peptide based on the mouse A-chain sequence was ineffective at blocking activation of C' by A beta in contrast to the inhibition seen with the human peptide. Comparison of mouse and human serum showed that human C' was activated more effectively by A beta than was mouse C'. Therefore, additional genetic manipulations may be necessary to replicate in the murine model the inflammation and neurodegeneration that occur in AD.
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Affiliation(s)
- S D Webster
- Department of Molecular Biology and Biochemistry, University of California Irvine, 92697-3900, USA
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50
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Bradley AJ, Brooks DE, Norris-Jones R, Devine DV. C1q binding to liposomes is surface charge dependent and is inhibited by peptides consisting of residues 14-26 of the human C1qA chain in a sequence independent manner. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1418:19-30. [PMID: 10209207 DOI: 10.1016/s0005-2736(99)00013-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Complement activation by anionic liposomes proceeds by antibody-independent, C1q-initiated activation of the classical pathway. Purified C1q bound to anionic liposomes in an acidic lipid concentration-dependent manner. Saturation binding, but not the apparent association constant, was enhanced by increasing the cardiolipin content of the liposomes or decreasing either the pH or ionic strength of the reaction mixture. These observations indicate the involvement of electrostatic factors in the binding. A highly cationic region in the collagen-like domain of C1q comprised of residues 14-26 of the C1qA polypeptide chain was assessed for involvement in liposome binding. This region has previously been shown to mediate C1q binding to other immunoglobulin-independent activators of the classical pathway of complement. Peptides containing residues 14-26 of C1qA, denoted C1qA14-26, inhibited C1q binding to and complement activation by anionic liposomes. The inhibitory capacity of these cationic peptides had no sequence or conformation specificity. Rather, the amount of positive charge on the peptides was the determining factor. When present in excess, peptides with five cationic residues inhibited C1q binding and complement activation; however, C1q peptides with only two cationic residues did not. In addition to the C1qA14-26 region, other parts of C1q that contain cationic residues may also be involved in C1q binding to anionic liposomes.
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Affiliation(s)
- A J Bradley
- Department of Pathology and Laboratory Medicine, University of British Columbia, 2211 Wesbrook Mall, Vancouver, BC V6T 2B5, Canada
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