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Yin Z, Guerrero J, Melendez R, Andrews B, Peng K. Development of a Cell-based Neutralizing Antibody Assay for Zinpentraxin Alfa: Challenges and Mitigation Strategies. AAPS J 2023; 25:75. [PMID: 37468730 DOI: 10.1208/s12248-023-00841-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 07/01/2023] [Indexed: 07/21/2023] Open
Abstract
Therapeutic protein drugs can potentially induce immune responses in patients and result in the production of anti-drug antibodies (ADAs), including a subset of ADAs called neutralizing antibodies (NAbs) that might cause loss of efficacy by inhibiting clinical activities of the drug. Herein, we describe the unique challenges encountered during the development of a fit-for-purpose cell-based NAb assay for a new protein modality, zinpentraxin alfa, including our strategies for assay design to overcome various matrix interferences and improve assay drug tolerance. We demonstrated that a typical biotin-drug extraction with acid dissociation (BEAD) approach alone was not sufficient to eliminate matrix interferences in this assay. Instead, the combination of the BEAD and ZebaTM spin size exclusion plate (SEP) was required to achieve the desirable assay performance. We also demonstrated that appropriate acidic buffers were critical in sample pretreatment to improve assay drug tolerance, which not only dissociated the drug/NAb immune complex but also effectively and irreversibly denatured the free drug. The final assay performed well with confirmed assay robustness and suitability for the clinical applications.
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Affiliation(s)
- Zhaojun Yin
- BioAnalytical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA, 94080, USA.
| | - Joyce Guerrero
- BioAnalytical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Rachel Melendez
- BioAnalytical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Ben Andrews
- BioAnalytical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Kun Peng
- BioAnalytical Sciences, Genentech, Inc., 1 DNA Way, South San Francisco, CA, 94080, USA
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2
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Pilely K, Fumagalli S, Rosbjerg A, Genster N, Skjoedt MO, Perego C, Ferrante AMR, De Simoni MG, Garred P. C-Reactive Protein Binds to Cholesterol Crystals and Co-Localizes with the Terminal Complement Complex in Human Atherosclerotic Plaques. Front Immunol 2017; 8:1040. [PMID: 28900428 PMCID: PMC5581807 DOI: 10.3389/fimmu.2017.01040] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 08/11/2017] [Indexed: 12/24/2022] Open
Abstract
Inflammation is a part of the initial process leading to atherosclerosis and cholesterol crystals (CC), found in atherosclerotic plaques, which are known to induce complement activation. The pentraxins C-reactive protein (CRP), long pentraxin 3 (PTX3), and serum amyloid P component (SAP) are serum proteins associated with increased risk of cardiovascular events and these proteins have been shown to interact with the complement system. Whether the pentraxins binds to CC and mediate downstream complement-dependent inflammatory processes remains unknown. Binding of CRP, PTX3, and SAP to CC was investigated in vitro by flow cytometry and fluorescence microscopy. CRP, PTX3, and SAP bound to CC in a concentration-dependent manner. CRP and PTX3 interacted with the complement pattern recognition molecule C1q on CC by increasing the binding of both purified C1q and C1q in plasma. However, CRP was the strongest mediator of C1q binding and also the pentraxin that most potently elevated C1q-mediated complement activation. In a phagocytic assay using whole blood, we confirmed that phagocytosis of CC is complement dependent and initiated by C1q-mediated activation. The pathophysiological relevance of the in vitro observations was examined in vivo in human atherosclerotic plaques. CRP, PTX3, and SAP were all found in atherosclerotic plaques and were located mainly in the cholesterol-rich necrotic core, but co-localization with the terminal C5b-9 complement complex was only found for CRP. In conclusion, this study identifies CRP as a strong C1q recruiter and complement facilitator on CC, which may be highly relevant for the development of atherosclerosis.
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Affiliation(s)
- Katrine Pilely
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Faculty of Health and Medical Sciences, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Stefano Fumagalli
- Istituto di Ricerche Farmacologiche Mario Negri, Department of Neuroscience, IRCCS, Milan, Italy
| | - Anne Rosbjerg
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Faculty of Health and Medical Sciences, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Ninette Genster
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Faculty of Health and Medical Sciences, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel-Ole Skjoedt
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Faculty of Health and Medical Sciences, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Carlo Perego
- Istituto di Ricerche Farmacologiche Mario Negri, Department of Neuroscience, IRCCS, Milan, Italy
| | - Angela M R Ferrante
- Università Cattolica del S.Cuore, Istituto di Patologia Chirurgica, Fondazione "Policlinico Universitario A. Gemelli", Polo Scienze cardiovascolari e toraciche, Roma, Italy
| | - Maria-Grazia De Simoni
- Istituto di Ricerche Farmacologiche Mario Negri, Department of Neuroscience, IRCCS, Milan, Italy
| | - Peter Garred
- Laboratory of Molecular Medicine, Department of Clinical Immunology, Section 7631, Faculty of Health and Medical Sciences, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
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3
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Daigo K, Inforzato A, Barajon I, Garlanda C, Bottazzi B, Meri S, Mantovani A. Pentraxins in the activation and regulation of innate immunity. Immunol Rev 2017; 274:202-217. [PMID: 27782337 DOI: 10.1111/imr.12476] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Humoral fluid phase pattern recognition molecules (PRMs) are a key component of the activation and regulation of innate immunity. Humoral PRMs are diverse. We focused on the long pentraxin PTX3 as a paradigmatic example of fluid phase PRMs. PTX3 acts as a functional ancestor of antibodies and plays a non-redundant role in resistance against selected microbes in mouse and man and in the regulation of inflammation. This molecule interacts with complement components, thus modulating complement activation. In particular, PTX3 regulates complement-driven macrophage-mediated tumor progression, acting as an extrinsic oncosuppressor in preclinical models and selected human tumors. Evidence collected over the years suggests that PTX3 is a biomarker and potential therapeutic agent in humans, and pave the way to translation of this molecule into the clinic.
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Affiliation(s)
- Kenji Daigo
- Department of Inflammation and Immunology, Humanitas Clinical and Research Center, Rozzano (Milan), Italy
| | - Antonio Inforzato
- Department of Inflammation and Immunology, Humanitas Clinical and Research Center, Rozzano (Milan), Italy.,Department of Medical Biotechnologies and Translational Medicine, University of Milan, Italy
| | | | - Cecilia Garlanda
- Department of Inflammation and Immunology, Humanitas Clinical and Research Center, Rozzano (Milan), Italy
| | - Barbara Bottazzi
- Department of Inflammation and Immunology, Humanitas Clinical and Research Center, Rozzano (Milan), Italy
| | - Seppo Meri
- Immunobiology Research Program, Research Programs Unit, Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki , Helsinki , Finland
| | - Alberto Mantovani
- Department of Inflammation and Immunology, Humanitas Clinical and Research Center, Rozzano (Milan), Italy.,Humanitas University, Rozzano, Italy
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4
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Abstract
Recognition and removal of apoptotic and necrotic cells must be efficient and highly controlled to avoid excessive inflammation and autoimmune responses to self. The complement system, a crucial part of innate immunity, plays an important role in this process. Thus, apoptotic and necrotic cells are recognized by complement initiators such as C1q, mannose binding lectin, ficolins, and properdin. This triggers complement activation and opsonization of cells with fragments of C3b, which enhances phagocytosis and thus ensures silent removal. Importantly, the process is tightly controlled by the binding of complement inhibitors C4b-binding protein and factor H, which attenuates late steps of complement activation and inflammation. Furthermore, factor H becomes actively internalized by apoptotic cells, where it catalyzes the cleavage of intracellular C3 to C3b. The intracellularly derived C3b additionally opsonizes the cell surface further supporting safe and fast clearance and thereby aids to prevent autoimmunity. Internalized factor H also binds nucleosomes and directs monocytes into production of anti-inflammatory cytokines upon phagocytosis of such complexes. Disturbances in the complement-mediated clearance of dying cells result in persistence of autoantigens and development of autoimmune diseases like systemic lupus erythematosus, and may also be involved in development of age-related macula degeneration.
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Affiliation(s)
- Myriam Martin
- Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, Malmö, Sweden
| | - Anna M Blom
- Division of Medical Protein Chemistry, Department of Translational Medicine, Lund University, Malmö, Sweden.
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5
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Williams KR, Colangelo CM, Hou L, Chung L, Belcher JM, Abbott T, Hall IE, Zhao H, Cantley LG, Parikh CR. Use of a Targeted Urine Proteome Assay (TUPA) to identify protein biomarkers of delayed recovery after kidney transplant. Proteomics Clin Appl 2017; 11. [PMID: 28261998 DOI: 10.1002/prca.201600132] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Revised: 01/17/2017] [Accepted: 03/01/2017] [Indexed: 11/07/2022]
Abstract
PURPOSE Development of delayed graft function (DGF) following kidney transplant is associated with poor outcomes. An ability to rapidly identify patients with DGF versus those with immediate graft function (IGF) may facilitate the treatment of DGF and the research needed to improve prognosis. The purpose of this study was to use a Targeted Urine Proteome Assay to identify protein biomarkers of delayed recovery from kidney transplant. EXPERIMENTAL DESIGN Potential biomarkers were identified using the Targeted Urine Proteome (MRM) Assay to interrogate the relative DGF/IGF levels of expression of 167 proteins in urine taken 12-18 h after kidney implantation from 21 DGF, 15 SGF (slow graft function), and 16 IGF patients. An iterative Random Forest analysis approach evaluated the relative importance of each biomarker, which was then used to identify an optimum biomarker panel that provided the maximum sensitivity and specificity with the least number of biomarkers. CONCLUSIONS AND CLINICAL RELEVANCE Four proteins were identified that together distinguished DGF with a sensitivity of 77.4%, specificity of 82.6%, and AUC of 0.891. This panel represents an important step toward identifying DGF at an early stage so that more effective treatments can be developed to improve long-term graft outcomes.
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Affiliation(s)
- Kenneth R Williams
- W.M. Keck Foundation Biotechnology Laboratory, Yale University School of Medicine, New Haven, USA
- Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, USA
| | | | - Lin Hou
- Center for Statistical Science, Tsinghua University, Beijing, China
| | - Lisa Chung
- W.M. Keck Foundation Biotechnology Laboratory, Yale University School of Medicine, New Haven, USA
| | - Justin M Belcher
- Internal Medicine, Yale University School of Medicine, New Haven, USA
| | - Thomas Abbott
- W.M. Keck Foundation Biotechnology Laboratory, Yale University School of Medicine, New Haven, USA
| | - Isaac E Hall
- Division of Nephrology, Hypertension & Renal Transplantation, Department of Internal Medicine, University of Utah School of Medicine, Salt Lake City, USA
| | - Hongyu Zhao
- Epidemiology & Public Health, Yale University School of Medicine, New Haven, USA
| | - Lloyd G Cantley
- Internal Medicine, Yale University School of Medicine, New Haven, USA
| | - Chirag R Parikh
- Internal Medicine, Yale University School of Medicine, New Haven, USA
- Program of Applied Translational Research, Yale University School of Medicine, New Haven, USA
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6
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Nonaka MI, Zsigmond E, Kudo A, Kawakami H, Yoshida K, Yoshida M, Kawano N, Miyado K, Nonaka M, Wetsel RA. Epididymal C4b-binding protein is processed and degraded during transit through the duct and is not essential for fertility. Immunobiology 2014; 220:467-75. [PMID: 25468721 DOI: 10.1016/j.imbio.2014.11.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Revised: 10/31/2014] [Accepted: 11/01/2014] [Indexed: 11/18/2022]
Abstract
C4b-binding protein (C4BP) is known as one of the circulating complement regulators that prevents excessive activation of the host-defense complement system. We have reported previously that C4BP is expressed abundantly in the rodent epididymis, one of the male reproductive organs connecting the testis and vas deferens, where immature spermatozoa acquire their motility and fertilizing ability during their transit through the duct. Epididymal C4BP (EpC4BP) is synthesized androgen-dependently by the epithelial cells, secreted into the lumen, and bound to the outer membrane of the passing spermatozoa. In this study, we found that EpC4BP is secreted as a large oligomer, similar to the serum C4BP, but is digested during the epididymal transit and is almost lost from both the luminal fluid and the sperm surface in the vas deferens. Such a processing pattern is not known in serum C4BP, suggesting that EpC4BP and serum C4BP might have different functional mechanisms, and that there is a novel function of EpC4BP in reproduction. In addition, the disappearance of EpC4BP from the sperm surface prior to ejaculation suggests that EpC4BP works only in the epididymis and would not work in the female reproductive tract to protect spermatozoa from complement attack. Next, we generated C4BP-deficient (C4BP-/-) mice to examine the possible role of EpC4BP in reproduction. However, the C4BP-/- mice were fertile and no significant differences were observed between the C4BP-/- and wild-type mouse spermatozoa in terms of morphology, motility, and rate of the spontaneous acrosome reaction. These results suggest that EpC4BP is involved in male reproduction, but not essential for sperm maturation.
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Affiliation(s)
- Mayumi I Nonaka
- Department of Biological Sciences, The University of Tokyo, Tokyo, Japan.
| | - Eva Zsigmond
- The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, USA
| | - Akihiko Kudo
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Japan
| | - Hayato Kawakami
- Department of Anatomy, Kyorin University School of Medicine, Mitaka, Japan
| | - Kaoru Yoshida
- Biomedical Engineering Center, Toin University of Yokohama, Yokohama, Japan
| | - Manabu Yoshida
- Misaki Marine Biological Station, The University of Tokyo, Miura, Japan
| | - Natsuko Kawano
- Department of Reproductive Biology, National Center for Child Health and Development, Tokyo, Japan
| | - Kenji Miyado
- Department of Reproductive Biology, National Center for Child Health and Development, Tokyo, Japan
| | - Masaru Nonaka
- Department of Biological Sciences, The University of Tokyo, Tokyo, Japan
| | - Rick A Wetsel
- The Brown Foundation Institute of Molecular Medicine, University of Texas Health Science Center at Houston, USA
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7
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Grosskinsky S, Schott M, Brenner C, Cutler SJ, Simon MM, Wallich R. Human complement regulators C4b-binding protein and C1 esterase inhibitor interact with a novel outer surface protein of Borrelia recurrentis. PLoS Negl Trop Dis 2010; 4:e698. [PMID: 20532227 PMCID: PMC2879370 DOI: 10.1371/journal.pntd.0000698] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Accepted: 04/06/2010] [Indexed: 11/23/2022] Open
Abstract
The spirochete Borrelia recurrentis is the causal agent of louse-borne relapsing fever and is transmitted to humans by the infected body louse Pediculus humanus. We have recently demonstrated that the B. recurrentis surface receptor, HcpA, specifically binds factor H, the regulator of the alternative pathway of complement activation, thereby inhibiting complement mediated bacteriolysis. Here, we show that B. recurrentis spirochetes express another potential outer membrane lipoprotein, termed CihC, and acquire C4b-binding protein (C4bp) and human C1 esterase inhibitor (C1-Inh), the major inhibitors of the classical and lectin pathway of complement activation. A highly homologous receptor for C4bp was also found in the African tick-borne relapsing fever spirochete B. duttonii. Upon its binding to B. recurrentis or recombinant CihC, C4bp retains its functional potential, i.e. facilitating the factor I-mediated degradation of C4b. The additional finding that ectopic expression of CihC in serum sensitive B. burgdorferi significantly increased spirochetal resistance against human complement suggests this receptor to substantially contribute, together with other known strategies, to immune evasion of B. recurrentis. Borrelia recurrentis, the causal agent of louse-borne relapsing fever is transmitted to humans via infected body lice. Infection with B. recurrentis has been achieved only in humans and is accompanied by a systemic inflammatory disease, multiple relapses of fever and massive spirochetemia. A key virulence factor of B. recurrentis is their potential to undergo antigenic variation. However, for survival in the blood during the early phase of infection and for persistence in human tissues, spirochetes must be endowed with robust tools to escape innate immunity. We have recently shown that B. recurrentis acquires the serum-derived regulator factor H, thereby blocking the alternative complement pathway. Here, we show that B. recurrentis expresses in addition a novel outer surface lipoprotein that selectively binds serum-derived C4b-binding protein and C1 esterase inhibitor, two endogenous regulators of the classical and lectin pathway of complement activation. The combined data underscore the versatility of B. recurrentis to effectively evade innate and adaptive immunity, including serum resistance. Thus, the present study elucidates a new mechanism of B. recurrentis important for its evasion from complement attack and will be helpful for the development of new drugs against this fatal infection.
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Affiliation(s)
- Sonja Grosskinsky
- Infectious Immunology Group, Institute for Immunology, University of Heidelberg, Heidelberg, Germany
| | - Melanie Schott
- Infectious Immunology Group, Institute for Immunology, University of Heidelberg, Heidelberg, Germany
| | - Christiane Brenner
- Infectious Immunology Group, Institute for Immunology, University of Heidelberg, Heidelberg, Germany
| | - Sally J. Cutler
- School of Health and Bioscience, University of East London, Stratford, London, United Kingdom
| | - Markus M. Simon
- Infectious Immunology Group, Institute for Immunology, University of Heidelberg, Heidelberg, Germany
| | - Reinhard Wallich
- Infectious Immunology Group, Institute for Immunology, University of Heidelberg, Heidelberg, Germany
- * E-mail:
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8
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Bergsma D, Chen S, Buchweitz J, Gerszten R, Haab BB. Antibody-array interaction mapping, a new method to detect protein complexes applied to the discovery and study of serum amyloid P interactions with kininogen in human plasma. Mol Cell Proteomics 2009; 9:446-56. [PMID: 20023212 DOI: 10.1074/mcp.m900418-mcp200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein-protein interactions are fundamentally important in biological processes, but the existing analytical tools have limited ability to sensitively and precisely measure the dynamic composition of protein complexes in biological samples. We report here the development of antibody-array interaction mapping (AAIM) to address that need. We used AAIM to probe interactions among a set of 48 proteins in serum and found several known interactions as well potentially novel interactions, including multiprotein clusters of interactions. A novel interaction initially identified between the innate immune system protein C-reactive protein and the inflammatory protein kininogen (KNG) was confirmed in subsequent experiments to involve serum amyloid P instead of its highly related family member, C-reactive protein. AAIM was used in a variety of formats to further study this interaction. In vitro studies confirmed the ability of the purified proteins to interact and revealed a zinc dependence of the interaction. Studies using plasma samples collected longitudinally following a controlled myocardial infarction revealed no consistent changes in the serum amyloid P-KNG interaction levels but consistent changes in KNG activation and interactions with plasma prekallikrein. These results demonstrate a versatile platform for measuring the dynamic composition of protein complexes in biological samples that should have value for studies of normal and disease-related signaling networks, multiprotein clusters, or enzymatic cascades.
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Affiliation(s)
- Derek Bergsma
- Van Andel Research Institute, Grand Rapids, Michigan 49503, USA
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9
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Abstract
Adsorption of serum proteins to the liposomal surface plays a critical role in the clearance of liposomes from the blood circulation. In this review, we will discuss the role of the liposomal opsonins proposed so far in liposome clearance. Additional, related topics that will be addressed are the cell-surface receptors that might be involved in liposome elimination from the blood compartment and the effect of poly(ethylene glycol) (PEG) modification on prevention of liposome opsonization.
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Affiliation(s)
- Xuedong Yan
- Department of Cell Biology, Section Liposome Research, Groningen University Institute for Drug Exploration (GUIDE), Groningen, The Netherlands
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10
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Abstract
The adaptive component of innate immunity occurs during the course of infection when antigen presenting cells alter expression of soluble or surface associated pattern recognition receptors. This results in increased recognition of a broad spectrum of pathogens, enhancement of effector functions and altered regulation of the inflammatory response.
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11
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Tambourgi DV, Pedrosa MFF, de Andrade RMG, Billington SJ, Griffiths M, van den Berg CW. Sphingomyelinases D induce direct association of C1q to the erythrocyte membrane causing complement mediated autologous haemolysis. Mol Immunol 2007; 44:576-82. [PMID: 16540172 DOI: 10.1016/j.molimm.2006.02.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Revised: 01/31/2006] [Accepted: 02/07/2006] [Indexed: 10/24/2022]
Abstract
Bites by Loxosceles spiders can induce severe clinical symptoms, including dermonecrosis, thrombosis, vascular leakage, haemolysis and persistent inflammation. The causative toxin is a sphingomyelinase D (SMase D) that cleaves sphingomyelin into choline and ceramide-1-phosphate. A similar enzyme, showing comparable bioactivity, is secreted by certain pathogenic corynebacteria and acts as a potent virulence factor. We have previously found that SMase D toxins led to an increased susceptibility of human erythrocytes (E) to activation of complement (C) via the classical pathway (CP) in the absence of antibodies. In the present study we have investigated the CP initiating components involved in the haemolysis induced by SMases from Corynebacterium pseudotuberculosis (PLD) and from Loxosceles intermedia venom (P1). When P1 or PLD treated E were incubated with C8-depleted human serum, an increase in C1q, serum amyloid protein (SAP) and C-reactive protein (CRP) binding was observed. While purified C1q, SAP and CRP were found to bind to P1 or PLD treated E, depletion of SAP or CRP from human serum did not prevent C-mediated lysis, suggesting that pentraxins are not involved in the initiation of C-activation. However depletion of C1 lead to a greatly reduced haemolysis, demonstrating that the activation of the CP is caused by direct binding of C1q to the SMase treated cells. Binding of fluid phase C-regulators C4b-binding protein and factor H was also observed, however these C-regulators in conjunction with the membrane bound C-regulators were unable to prevent haemolysis, demonstrating the potency of SMase D facilitated binding of C1 and activation of C.
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Affiliation(s)
- D V Tambourgi
- Laboratório de Imunoquímica, Instituto Butantan, São Paulo, Brazil.
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12
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Persson J, Lindahl G. Single-step purification of human C4b-binding protein (C4BP) by affinity chromatography on a peptide derived from a streptococcal surface protein. J Immunol Methods 2005; 297:83-95. [PMID: 15777933 DOI: 10.1016/j.jim.2004.11.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2004] [Revised: 11/10/2004] [Accepted: 11/30/2004] [Indexed: 01/06/2023]
Abstract
Many Gram-positive bacteria express surface proteins that bind human plasma proteins. These bacterial proteins, and derivatives of them, are of interest for analysis of bacterial pathogenesis and as immunochemical tools. Well-characterized examples include the IgG-binding reagents staphylococcal protein A and streptococcal protein G, and the recently described streptococcal IgA-binding peptide Sap. Here, we show that a peptide derived from the streptococcal M22 protein can be used for single-step affinity purification of the human complement regulator C4b-binding protein (C4BP). Binding of C4BP was strongly enhanced by dimerization of the peptide via a C-terminal cysteine residue not present in the intact M22 protein. The purified C4BP had the expected binding characteristics, and acted as a cofactor for factor I in the degradation of C4b. Passage of serum through a peptide column under non-saturating conditions resulted in binding of >99.5% of serum C4BP, implying that such a column can be used to deplete serum of C4BP. These data indicate that the C4BP-binding peptide is a versatile tool that can be used for simple and rapid purification of biologically active human C4BP or for removal of C4BP from serum.
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Affiliation(s)
- Jenny Persson
- Department of Medical Microbiology, Dermatology and Infection, Sölvegatan 23, 223 62 Lund, Sweden
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13
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Heeb MJ, Koenen RR, Fernández JA, Hackeng TM. Direct anticoagulant activity of protein S-C4b binding protein complex in Heerlen heterozygotes and normals. J Thromb Haemost 2004; 2:1766-73. [PMID: 15456488 DOI: 10.1111/j.1538-7836.2004.00901.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Plasma protein S normally circulates free (40%) or complexed with C4b-binding protein (PS-C4BP); only free protein S is a cofactor for activated protein C during factor (F) Va inactivation. Protein S-Heerlen lacks a carbohydrate group, leading to low plasma free protein S levels, but normal levels of PS-C4BP. OBJECTIVES Because protein S-Heerlen is not associated with thrombosis, we investigated whether PS-C4BP is directly anticoagulant in plasma and whether PS-Heerlen-C4BP has enhanced direct anticoagulant activity. METHODS An assay for protein S direct activity was applied to Heerlen-heterozygous plasmas. Free and complexed protein S were repeatedly isolated from normal and Heerlen-heterozygous plasmas and tested for direct anticoagulant activity in prothrombinase assays and in plasma. RESULTS Heerlen-heterozygous plasmas were deficient in free and total protein S antigen but had normal to high protein S direct anticoagulant activity. Purified Heerlen-heterozygous PS-C4BP was 7-fold more potent than normal PS-C4BP in inhibiting full prothrombinase activity, and 22-fold more potent in inhibiting prothrombin activation in the absence of FVa; it also specifically prolonged plasma clotting times 14-fold more than normal PS-C4BP. Heerlen-heterozygous PS-C4BP did not compete for limiting phospholipids any better than normal PS-C4BP. However, ligand blots and surface plasmon resonance studies showed that Heerlen-heterozygous PS-C4BP bound more avidly to FXa than did normal PS-C4BP (apparent Kd = 4.3 nm vs. 82 nm). CONCLUSIONS Plasma-derived PS-C4BP has direct anticoagulant activity in plasma and in purified systems. Enhanced direct activity of PS-Heerlen-C4BP may compensate for low free protein S levels and low cofactor activity in individuals with protein S-Heerlen.
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Affiliation(s)
- M J Heeb
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA.
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14
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Blom AM, Villoutreix BO, Dahlbäck B. Complement inhibitor C4b-binding protein-friend or foe in the innate immune system? Mol Immunol 2004; 40:1333-46. [PMID: 15072852 DOI: 10.1016/j.molimm.2003.12.002] [Citation(s) in RCA: 130] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Revised: 12/09/2003] [Accepted: 12/11/2003] [Indexed: 01/15/2023]
Abstract
The complement system constitutes an important component of the defence against foreign organisms, functioning both in innate and adaptive immune systems. It is potentially harmful also to the own organism and is therefore tightly regulated by a number of membrane-bound and soluble factors. C4b-binding protein (C4BP) is a potent circulating soluble inhibitor of the classical and lectin pathways of complement. In recent years, the relationships between the structure of C4BP and its functions have been elucidated using a combination of computer-based molecular analysis and recombinant DNA technologies. Moreover, two novel functions have recently been ascribed to C4BP. One is the ability of C4BP to localize complement regulatory activity to the surface of apoptotic cells via its interaction with the membrane-binding vitamin K-dependent protein S. The other is the ability of C4BP to act as a survival factor for B cells due to an interaction with CD40. The complement regulatory activity of C4BP is not only beneficial because it is also explored by pathogens such as Neisseria gonorrhoeae, Bordetella pertussis, Streptococcus pyogenes, Escherichia coli K1, and Candida albicans, that bind C4BP to their surfaces. This contributes to the serum resistance and the pathogenicity of these bacteria. In this review, the structural requirements and functional importance of the interactions between C4BP and its various ligands are discussed.
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Affiliation(s)
- Anna M Blom
- The Wallenberg Laboratory, Department of Clinical Chemistry, University Hospital Malmö, Lund University, S-205 02 Malmö, Sweden.
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15
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Pilling D, Buckley CD, Salmon M, Gomer RH. Inhibition of fibrocyte differentiation by serum amyloid P. THE JOURNAL OF IMMUNOLOGY 2004; 171:5537-46. [PMID: 14607961 PMCID: PMC4482350 DOI: 10.4049/jimmunol.171.10.5537] [Citation(s) in RCA: 237] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Wound healing and the dysregulated events leading to fibrosis both involve the proliferation and differentiation of fibroblasts and the deposition of extracellular matrix. Whether these fibroblasts are locally derived or from a circulating precursor population is unclear. Fibrocytes are a distinct population of fibroblast-like cells derived from peripheral blood monocytes that enter sites of tissue injury to promote angiogenesis and wound healing. We have found that CD14(+) peripheral blood monocytes cultured in the absence of serum or plasma differentiate into fibrocytes within 72 h. We purified the factor in serum and plasma that prevents the rapid appearance of fibrocytes, and identified it as serum amyloid P (SAP). Purified SAP inhibits fibrocyte differentiation at levels similar to those found in plasma, while depleting SAP reduces the ability of plasma to inhibit fibrocyte differentiation. Compared with sera from healthy individuals and patients with rheumatoid arthritis, sera from patients with scleroderma and mixed connective tissue disease, two systemic fibrotic diseases, were less able to inhibit fibrocyte differentiation in vitro and had correspondingly lower serum levels of SAP. These results suggest that low levels of SAP may thus augment pathological processes leading to fibrosis. These data also suggest mechanisms to inhibit fibrosis in chronic inflammatory conditions, or conversely to promote wound healing.
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Affiliation(s)
- Darrell Pilling
- Howard Hughes Medical Institute, Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005
| | - Christopher D. Buckley
- Department of Rheumatology, Rheumatology Research Group, University of Birmingham/Medical Research Council Centre for Immune Regulation, Medical School, University of Birmingham, Birmingham, West Midlands, United Kingdom
| | - Mike Salmon
- Department of Rheumatology, Rheumatology Research Group, University of Birmingham/Medical Research Council Centre for Immune Regulation, Medical School, University of Birmingham, Birmingham, West Midlands, United Kingdom
| | - Richard H. Gomer
- Howard Hughes Medical Institute, Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005
- Address correspondence and reprint requests to: Dr. Richard H. Gomer, Department of Biochemistry and Cell Biology, MS-140, Rice University, Houston, TX 77005-1892.
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16
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Nonaka MI, Hishikawa Y, Moriyama N, Koji T, Ogata RT, Kudo A, Kawakami H, Nonaka M. Complement C4b-binding protein as a novel murine epididymal secretory protein. Biol Reprod 2003; 69:1931-9. [PMID: 12930719 DOI: 10.1095/biolreprod.103.020289] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Complement C4b-binding protein (C4BP) is a plasma protein synthesized in the liver and plays a regulatory role in the host defense complement system. We have previously reported that mRNAs of the C4BP alpha chain (C4BPalpha) are expressed at significant levels in the guinea pig and mouse epididymis in an androgen-dependent manner. Here, we analyze the murine C4bpa gene and show that epididymal and liver C4BPalpha mRNAs are generated from a single-copy gene and that the epididymal C4BPalpha mRNAs are transcribed from novel transcription start sites located approximately 100 base pairs downstream from those used in the liver. Furthermore, in an immunohistochemical study using rabbit anti-mouse C4BP antiserum, we demonstrated that C4BP is localized in the stereocilia and Golgi apparatus of the epididymal epithelial cells and the surfaces of spermatozoa in the lumen in the region from the distal caput to the cauda but not in the proximal caput region. Indirect immunofluorescence of the isolated spermatozoa demonstrated that C4BP is localized preferentially on the head region of the spermatozoa, and immunoelectron microscopy located C4BP on the plasma membrane and the outer acrosomal membrane. These results indicate that epididymal C4BP is synthesized in the epithelial cells and secreted into the lumen in a region-restricted manner and is taken up to the sperm membranes on passage through the epididymis. Many epididymal proteins are secreted from the epithelial cells in a region-specific and androgen-dependent manner and are considered to contribute to sperm maturation. Our findings suggest a novel function of C4BP as one such epididymal secretory protein.
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Affiliation(s)
- Mayumi I Nonaka
- Department of Biological Sciences, University of Tokyo, Tokyo 133-0033, Japan.
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17
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Blom AM, Villoutreix BO, Dahlbäck B. Mutations in alpha-chain of C4BP that selectively affect its factor I cofactor function. J Biol Chem 2003; 278:43437-42. [PMID: 12893820 DOI: 10.1074/jbc.m306620200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
C4b-binding protein (C4BP) inhibits all pathways of complement activation, acting as a cofactor to the serine protease factor I (FI) in the degradation of activated complement factors C4b and C3b. C4BP is a disulfide-linked polymer of seven alpha-chains and a unique beta-chain, the alpha- and beta-chains being composed of eight and three complement control protein (CCP) domains, respectively. In previous studies we have localized cofactor activity and binding of C4b to alpha-chain CCP1-3 of C4BP, whereas the binding of C3b required additionally CCP4. Likewise, introduced point mutations that decreased binding of C4b/C3b caused a decrease in cofactor activity. In the present study, we describe two mutants of C4BP, K126Q/K128Q and F144S/F149S, clustered on alpha-chain CCP3, which selectively lost their ability to act as cofactors in the cleavage of both C4b and C3b. Both mutants show the same binding affinity for C4b/C3b as measured by surface plasmon resonance and have the same inhibitory effect on formation and decay of the classical pathway C3-convertase as the wild type C4BP. It appears that C4b and C3b do not undergo the same conformational changes upon binding to the C4BP mutants as during the interaction with the wild type C4BP, which then results in the observed loss of the cofactor activity.
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Affiliation(s)
- Anna M Blom
- Lund University Department of Clinical Chemistry, University Hospital Malmö, The Wallenberg Laboratory, S-205 02 Malmö, Sweden and INSERM U428, Université Paris V, Paris 75006, France.
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18
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Brodeur SR, Angelini F, Bacharier LB, Blom AM, Mizoguchi E, Fujiwara H, Plebani A, Notarangelo LD, Dahlback B, Tsitsikov E, Geha RS. C4b-binding protein (C4BP) activates B cells through the CD40 receptor. Immunity 2003; 18:837-48. [PMID: 12818164 DOI: 10.1016/s1074-7613(03)00149-3] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We demonstrate that the alpha chain of human C4b binding protein (C4BP) binds directly to CD40 on human B cells at a site that differs from that used by CD40 ligand. C4BP induces proliferation, upregulation of CD54 and CD86 expression, and IL4-dependent IgE isotype switching in normal B cells but not in B cells from patients with CD40 or IKKgamma/NEMO deficiencies. Furthermore, C4BP colocalized with B cells in the germinal centers of human tonsils. These observations suggest that C4BP is an activating ligand for CD40 and establish a novel interface between complement and B cell activation.
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Affiliation(s)
- Scott R Brodeur
- Division of Immunology, Children's Hospital and Department of Pediatrics, Harvard Medical School, Boston, MA, USA
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19
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Webb JH, Blom AM, Dahlbäck B. Vitamin K-dependent protein S localizing complement regulator C4b-binding protein to the surface of apoptotic cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:2580-6. [PMID: 12193728 DOI: 10.4049/jimmunol.169.5.2580] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Apoptosis is characterized by a lack of inflammatory reaction in surrounding tissues, suggesting local control of complement activation. During the initial stage of apoptosis, cells expose negatively charged phospholipid phosphatidylserine on their surfaces. The vitamin K-dependent protein S has a high affinity for this type of phospholipid. In human plasma, 60-70% of protein S circulates in complex with C4b-binding protein (C4BP). The reason why protein S and C4BP form a high-affinity complex in plasma is not known. However, C4BP is an important regulator of the classical pathway of the complement system where it acts as a cofactor in degradation of complement protein C4b. Using Jurkat cells as a model system for apoptosis, we now show protein S to bind to apoptotic cells. We further demonstrate protein S-mediated binding of C4BP to apoptotic cells. Binding of the C4BP-protein S complex to apoptotic cells was calcium-dependent and could be blocked with Abs directed against the phospholipid-binding domain in protein S. Annexin V, which binds to exposed phosphatidylserine on the apoptotic cell surface, could inhibit the binding of protein S. The C4BP that was bound via protein S to the apoptotic cells was able to interact with the complement protein C4b, supporting a physiological role of the C4BP/protein S complex in regulation of complement on the surface of apoptotic cells.
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Affiliation(s)
- Joanna H Webb
- Division of Clinical Chemistry, Department of Laboratory Medicine, University Hospital Malmö, Lund University, Sweden
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20
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Sen JW, Heegaard NHH. Serum amyloid p component does not circulate in complex with C4-binding protein, fibronectin or any other major protein ligand. Scand J Immunol 2002; 56:85-93. [PMID: 12100475 DOI: 10.1046/j.1365-3083.2002.01109.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Serum amyloid P component (SAP) is a pentameric plasma protein associated with all known kinds of amyloid. The normal physiological function of the protein has not been fully elucidated but it may be involved in clearance of cellular debris and in innate immunity. An important clue to its normal function is the identity of ligands bound to SAP in the circulation. It has been reported that all SAP is complexed with C4-binding protein (C4bp) but other studies have not been able to confirm this. We here study this issue by a combination of crossed immunoelectrophoresis (CIE), size exclusion chromatography, and native polyacrylamide electrophoresis and we show that SAP in serum - analysed under native analysis conditions and free of immobilizing antibodies - does not have any major protein ligand. However, when the protein is aggregated by immobilized antibodies, C4bp and fibronectin clearly bind to SAP. If circulating SAP under normal circumstances bind any protein ligand in vivo, our results strongly suggest that this only occurs to a minor extent.
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Affiliation(s)
- J W Sen
- Department of Autoimmunology, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen, Denmark
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21
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Westein E, Denis CV, Bouma BN, Lenting PJ. The alpha -chains of C4b-binding protein mediate complex formation with low density lipoprotein receptor-related protein. J Biol Chem 2002; 277:2511-6. [PMID: 11705989 DOI: 10.1074/jbc.m102293200] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
C4b-binding protein (C4BP) is a heparin-binding protein that participates in both the complement and hemostatic system. We investigated the interaction between C4BP and low density lipoprotein receptor-related protein (LRP), an endocytic receptor involved in the catabolism of various heparin-binding proteins. Both plasma-derived C4BP and recombinant C4BP consisting of only its alpha-chains (rC4BPalpha) bound efficiently to immobilized LRP, as determined by surface plasmon resonance analysis. Complementary, two distinct fragments of LRP, i.e. clusters II and IV, both associated to immobilized rC4BPalpha, and binding could be inhibited by the LRP antagonist receptor-associated protein. Further analysis showed that association of rC4BPalpha to LRP was inhibited by heparin or by anti-C4BP antibody RU-3B9, which recognizes the heparin-binding region of the C4BP alpha-chains. In cellular degradation experiments, LRP-expressing fibroblasts effectively degraded (125)I-labeled rC4BPalpha, whereas their LRP-deficient counterparts displayed a 4-fold diminished capacity of degrading (125)I-rC4BPalpha. Finally, initial clearance of C4BP in mice was significantly delayed upon co-injection with receptor-associated protein. In conclusion, our data demonstrate that the alpha-chains of C4BP comprise a binding site for LRP. We propose that LRP mediates at least in part the catabolism of C4BP and, as such, may regulate C4BP participation in complement and hemostatic processes.
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Affiliation(s)
- Erik Westein
- Laboratory for Thrombosis and Haemostasis, Department of Haematology, University Medical Center Utrecht, 3584 CX Utrecht, The Netherlands
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22
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Kimura T, Tani S, Matsumoto Yi Y, Takeda T. Serum amyloid P component is the Shiga toxin 2-neutralizing factor in human blood. J Biol Chem 2001; 276:41576-9. [PMID: 11533067 DOI: 10.1074/jbc.m107819200] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
It has been suggested that some factor present in human plasma binds to Shiga toxin 2 (Stx2) and neutralizes it in vitro (Bitzan, M., Klemt, M., Steffens, R., and Muller-Wiefel, D. E. (1993) Infection 21, 140-145). This factor does not exist in other species (Caprioli, A., Luzzi, I., Seganti, L., Marchetti, M., Karmali, M., Clarke, I., and Boyd, B. (1994) Recent Adv. VTEC Infect. 353-356). Because analysis of this factor is important to understanding the pathology induced by Shiga toxin-producing Escherichia coli, we purified this factor from human plasma and identified it. Purification was carried out by serially subjecting human plasma to Con A-Sepharose, DEAE-Sepharose, hydroxyapatite, and gel-filtration high performance liquid chromatography (HPLC), using Stx2-neutralizing activity as the indicator. The gel-filtration HPLC fraction yielded a single band on SDS-polyacrylamide gel electrophoresis. Twenty N-terminal amino acid residues of this fraction were analyzed and found to correspond perfectly to human serum amyloid P component (HuSAP). Because commercially available HuSAP also showed Stx2 binding and neutralizing activity, we identified this factor as HuSAP.
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Affiliation(s)
- T Kimura
- Teijin Institute for Biomedical Research, Teijin Ltd., 4-3-2, Asahigaoka, Hino City, Tokyo 191-8512, Japan.
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23
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Bharadwaj D, Mold C, Markham E, Du Clos TW. Serum amyloid P component binds to Fc gamma receptors and opsonizes particles for phagocytosis. THE JOURNAL OF IMMUNOLOGY 2001; 166:6735-41. [PMID: 11359830 DOI: 10.4049/jimmunol.166.11.6735] [Citation(s) in RCA: 133] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Serum amyloid P component (SAP) is a member of the pentraxin family of proteins. These proteins are characterized by cyclic pentameric structure, calcium-dependent ligand binding, and frequent regulation as acute-phase serum proteins. SAP is the serum precursor of the P component of amyloid. It binds to a broad group of molecules, including autoantigens, through a pattern recognition binding site. The related pentraxin, C-reactive protein (CRP), is a strong acute-phase reactant in man and an opsonin. We previously determined that the binding of CRP to leukocytes occurs through Fc receptors for IgG (FcgammaR). We now report that SAP also binds to FcgammaR and opsonizes particles for phagocytosis by human polymorphonuclear leukocytes (PMN). Specific, saturable binding of SAP to FcgammaRI, FcgammaRIIa, and FcgammaRIIIb expressed on transfected COS cells was detected using SAP-biotin and PE-streptavidin. Zymosan was used to test the functional consequences of SAP and CRP binding to FcgammaR. Both SAP and CRP bound to zymosan and enhanced its uptake by PMN. This enhanced phagocytosis was abrogated by treatment of PMN with wortmannin, a phosphatidylinositol-3 kinase inhibitor, or with piceatannol, a Syk inhibitor, consistent with uptake through FcgammaR. Treatment of PMN with phosphatidylinositol-specific phospholipase C to remove FcgammaRIIIb also decreased phagocytosis of SAP-opsonized zymosan, but not CRP-opsonized zymosan. These results suggest that SAP may function in host defense. In addition, as SAP binds to chromatin, a major immunogen in systemic lupus erythematosus, it may provide a clearance mechanism for this Ag through FcgammaR bearing cells.
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Affiliation(s)
- D Bharadwaj
- Veterans Affairs Medical Center, 1501 San Pedro Southeast, Albuquerque, NM 87108, USA
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24
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Familian A, Zwart B, Huisman HG, Rensink I, Roem D, Hordijk PL, Aarden LA, Hack CE. Chromatin-independent binding of serum amyloid P component to apoptotic cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:647-54. [PMID: 11441067 DOI: 10.4049/jimmunol.167.2.647] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Human serum amyloid P component (SAP) is a glycoprotein structurally belonging to the pentraxin family of proteins, which has a characteristic pentameric organization. Mice with a targeted deletion of the SAP gene develop antinuclear Abs, which was interpreted as evidence for a role of SAP in controlling the degradation of chromatin. However, in vitro SAP also can bind to phosphatidylethanolamine, a phospholipid which in normal cells is located mainly in the inner leaflet of the cell membrane, to be translocated to the outer leaflet of the cell membrane during a membrane flip-flop. We hypothesized that SAP, because of its specificity for phosphatidylethanolamine, may bind to apoptotic cells independent of its nuclear binding. Calcium-dependent binding of SAP to early, nonpermeable apoptotic Jurkat, SKW, and Raji cells was indeed observed. Experiments with flip-flopped erythrocytes confirmed that SAP bound to early apoptotic cells via exposed phosphatidylethanolamine. Binding of SAP was stronger to late, permeable apoptotic cells. Experiments with enucleated neutrophils, with DNase/RNase treatment of late apoptotic Jurkat cells, and competition experiments with histones suggested that binding of SAP to late apoptotic cells was largely independent of chromatin. Confocal laser microscopic studies indeed suggested that SAP bound to these apoptotic cells mainly via the blebs. Thus, this study shows that SAP binds to apoptotic cells already at an early stage, which raises the possibility that SAP is involved in dealing with apoptotic cells in vivo.
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Affiliation(s)
- A Familian
- CLB, Sanquin Blood Supply Foundation and Laboratory for Experimental and Clinical Immunology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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25
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Nonaka MI, Wang G, Mori T, Okada H, Nonaka M. Novel androgen-dependent promoters direct expression of the C4b-binding protein alpha-chain gene in epididymis. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:4570-7. [PMID: 11254714 DOI: 10.4049/jimmunol.166.7.4570] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
C4b-binding protein (C4BP) is a large plasma protein composed of seven alpha-chains and one beta-chain and is involved in the fluid phase regulation of the classical pathway of the complement system. Complement inhibitory activity is located in the alpha-chain, and its mRNA has been detected only in liver to date. Here, we have isolated cDNA clones encoding the alpha-chain of guinea pig C4BP (C4BP alpha) and have demonstrated significant C4BP alpha mRNA expression in epididymis as well as liver. The level of C4BP alpha transcripts increased in the epididymis after birth, while it remained constant in the liver. C4BP alpha mRNA was also detected in the normal murine epididymis at a significant level, but it decreased drastically after castration, suggesting that epididymal expression of the C4BP alpha gene is regulated by androgen. Gene analysis of guinea pig C4BP alpha indicated that liver and epididymis C4BP alpha mRNA share the coding region and 3'-untranslated region, but are transcribed from independent promoters on a single-copy gene. Two novel epididymis-specific promoters were identified in the region corresponding to the first intron of liver transcripts. The binding motif for hepatocyte NF-1 occurs in the promoter used for transcription of liver C4BP alpha, whereas androgen-responsive elements occur in both promoters used in the epididymis. These findings present a novel link between complement regulators and reproduction. Furthermore, variation in the 5'-untranslated regions, arising from alternative splicing of the newly identified exons, is demonstrable in the guinea pig C4BP alpha transcripts.
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Affiliation(s)
- M I Nonaka
- Department of Biological Sciences, University of Tokyo, Tokyo, Japan.
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26
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Webb JH, Villoutreix BO, Dahlback B, Blom AM. Localization of a hydrophobic binding site for anticoagulant protein S on the beta -chain of complement regulator C4b-binding protein. J Biol Chem 2001; 276:4330-7. [PMID: 11050085 DOI: 10.1074/jbc.m006541200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
C4b-binding protein (C4BP) is a plasma glycoprotein involved in regulation of the complement system. C4BP consists of seven alpha-chains and one unique beta-chain, all constructed of repeating complement control protein (CCP) modules. The beta-chain, made up of three CCPs, binds tightly to vitamin K-dependent protein S, a cofactor to anticoagulant activated protein C. When bound to C4BP, protein S loses its activated protein C cofactor function. In this study, we have mutated potentially important amino acids located at the surface of CCP1 of the beta-chain to probe the protein S-C4BP interaction. The substitutions were designed after analysis of a homology-based three-dimensional structure of the beta-chain and were L27T/F45Q, I16S/V18S, V31T/I33N, I16S/V18S/V31T/I33N, L38S/V39S, and K41E/K42E. The mutants were expressed in a prokaryotic system, purified using an N-terminal His-tag, refolded using an oxido-shuffling system, and tested in several assays for their ability to bind protein S. Our data define Ile(16), Val(18), Val(31), and Ile(33) as crucial for protein S binding, with secondary effects from Leu(38) and Val(39). In addition, Lys(41) and Lys(42) contribute slightly to the interaction. Our results further confirm that surface hydrophobicity analysis may be used to identify ligand recognition sites.
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Affiliation(s)
- J H Webb
- Division of Clinical Chemistry, Department of Laboratory Medicine, Lund University, University Hospital Malmö, Malmö S-205 02, Sweden
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27
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28
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Blom AM, Zadura AF, Villoutreix BO, Dahlbäck B. Positively charged amino acids at the interface between alpha-chain CCP1 and CCP2 of C4BP are required for regulation of the classical C3-convertase. Mol Immunol 2000; 37:445-53. [PMID: 11090879 DOI: 10.1016/s0161-5890(00)00059-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
C4b-binding protein (C4BP) is an abundant and potent down-regulator of complement activation. In its presence, the assembly of the classical pathway C3-convertase is prevented and its natural decay is accelerated. C4BP also acts as a cofactor to the serine proteinase factor I in the cleavage of C4b. C4BP contains repeats of small structural domains: complement control protein (CCP) modules. Previously, we constructed and purified nine recombinant C4BP molecules in which solvent exposed positively charged amino acids at the interface between CCP1 and CCP2 were mutated to polar glutamines. Several of these mutants showed lower binding ability for C4b. In the present investigation, the collection of mutants was tested with functional assays and we found a correlation between changes in the apparent affinity of C4BP mutants for C4b and their ability to down regulate the C3-convertase. Mutagenesis of R(39), K(63), R(64) and particularly H(67) resulted in impaired C4b binding paralleled by lost ability of the C4BP mutants to prevent C3-convertase assembly and to increase the decay rate of the C3-convertase. Furthermore, these amino acids were found to be crucial for the factor I cofactor activity of C4BP in fluid phase degradation of C4b. In conclusion, a cluster of positively charged amino acid residues at the CCP1-CCP2 interface is identified as functionally important in the regulation of the C3-convertase by C4BP.
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Affiliation(s)
- A M Blom
- Department of Clinical Chemistry, The Wallenberg Laboratory, Lund University, University Hospital Malmö, S-205 02 Malmö, Sweden.
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29
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de Haas CJ, van Leeuwen EM, van Bommel T, Verhoef J, van Kessel KP, van Strijp JA. Serum amyloid P component bound to gram-negative bacteria prevents lipopolysaccharide-mediated classical pathway complement activation. Infect Immun 2000; 68:1753-9. [PMID: 10722560 PMCID: PMC97344 DOI: 10.1128/iai.68.4.1753-1759.2000] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although serum amyloid P component (SAP) is known to bind many ligands, its biological function is not yet clear. Recently, it was demonstrated that SAP binds to lipopolysaccharide (LPS). In the present study, SAP was shown to bind to gram-negative bacteria expressing short types of LPS or lipo-oligosaccharide (LOS), such as Salmonella enterica serovar Copenhagen Re and Escherichia coli J5, and also to clinical isolates of Haemophilus influenzae. It was hypothesized that SAP binds to the bacteria via the lipid A part of LPS or LOS, since the htrB mutant of the nontypeable H. influenzae strain NTHi 2019-B29-3, which expresses a nonacetylated lipid A, did not bind SAP. This was in contrast to the parental strain NTHi 2019. The binding of SAP resulted in a clear inhibition of the deposition of complement component C3 on the bacteria. SAP inhibited only the activation of the classical complement pathway; the alternative route remained unaffected. In the classical route, SAP prevented the deposition of the first complement component, Clq, probably by interfering with the binding of Clq to LPS. Since antibody-mediated Clq activation was not inhibited by SAP, SAP seems to inhibit only the LPS-induced classical complement pathway activation. The SAP-induced inhibition of C3 deposition strongly diminished the complement-mediated lysis as well as the phagocytosis of the bacteria. The binding of SAP to gram-negative bacteria, therefore, might influence the pathophysiology of an infection with such bacteria.
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Affiliation(s)
- C J de Haas
- Department of Inflammation, Eijkman Winkler Institute, University Medical Center, 3584 CX Utrecht, The Netherlands.
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Blom AM, Webb J, Villoutreix BO, Dahlbäck B. A cluster of positively charged amino acids in the C4BP alpha-chain is crucial for C4b binding and factor I cofactor function. J Biol Chem 1999; 274:19237-45. [PMID: 10383431 DOI: 10.1074/jbc.274.27.19237] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
C4b-binding protein (C4BP) is a regulator of the classical complement pathway, acting as a cofactor to factor I in the degradation of C4b. Computer modeling and structural analysis predicted a cluster of positively charged amino acids at the interface between complement control protein modules 1 and 2 of the C4BP alpha-chain to be involved in C4b binding. Three C4BP mutants, R39Q, R64Q/R66Q, and R39Q/R64Q/R66Q, were expressed and assayed for their ability to bind C4b and to function as factor I cofactors. The apparent affinities of R39Q, R64Q/R66Q, and R39Q/R64Q/R66Q for immobilized C4b were 15-, 50-, and 140-fold lower, respectively, than that of recombinant wild type C4BP. The C4b binding site demonstrated herein was also found to be a specific heparin binding site. In C4b degradation, the mutants demonstrated decreased ability to serve as factor I cofactors. In particular, the R39Q/R64Q/R66Q mutant was inefficient as cofactor for cleavage of the Arg937-Thr938 peptide bond in C4b. In contrast, the factor I mediated cleavage of Arg1317-Asn1318 bond was less affected by the C4BP mutations. In conclusion, we identify a cluster of amino acids that is part of a C4b binding site involved in the regulation of the complement system.
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Affiliation(s)
- A M Blom
- The Wallenberg Laboratory, Department of Clinical Chemistry, Lund University, University Hospital Malmö, S-205 02 Malmö, Sweden
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Some Anticardiolipin Antibodies Recognize a Combination of Phospholipids With Thrombin-Modified Antithrombin, Complement C4b-Binding Protein, and Lipopolysaccharide Binding Protein. Blood 1999. [DOI: 10.1182/blood.v93.12.4248.412k24_4248_4255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The standard enzyme-linked immunosorbent assay (ELISA) for anticardiolipin antibodies (ACA) detects a heterogenous group of antibodies against cardiolipin on its own, β2-glycoprotein I (β2GPI), and, potentially, other phospholipid-binding plasma proteins from bovine or human origin. In an attempt to identify new proteic targets of ACA, we selected 6 patients who possessed cofactor-dependent ACA but no antibody to human or bovine β2GPI detectable in the β2GPI-ELISA. Three of these samples proved to recognize β2GPI in combination with cardiolipin, but not β2GPI directly immobilized on γ-irradiated polystyrene or agarose beads. In the other cases, the component required for ACA binding was purified from adult bovine serum or plasma by means of ammonium sulfate precipitation and chromatography on Phenyl-Sepharose, diethyl aminoethyl (DEAE)-cellulose, heparin-Ultrogel, and Sephacryl S-300 columns. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis coupled to N-terminal amino acid microsequencing identified the cofactors of patients no. 4, 5, and 6 ACA as lipopolysaccharide binding protein (LBP), complement C4b-binding protein (C4BP), and the thrombin-antithrombin (AT) complex, respectively. Adsorption of each of these cofactor preparations with cardiolipin liposomes led to suppression of ACA reactivity, concomitant with the loss of bands from SDS gels corresponding to sequenced material. Bacterial lipopolysaccharide (which forms high-affinity complexes with LBP) specifically neutralized the cofactor activity of the LBP preparation in a concentration-dependent manner. Bovine serum and plasma, as well as the C4BP preparation, optimally supported the binding of a rabbit anti-C4BP antiserum to immobilized cardiolipin. The binding of a rabbit anti-AT antiserum to solid-phase cardiolipin was sustained by the thrombin-AT preparation and bovine serum, but neither by bovine plasma nor by native AT, thus reproducing the behavior of patient no. 6 ACA. Taking advantage of the restricted recognition by the latter ACA of a cofactor from bovine origin appearing upon clotting, we studied the generation of such activity in human plasma supplemented with bovine AT or bovine prothrombin before clotting. In these conditions, patient no. 6 antibody binding to cardiolipin required the addition of bovine AT, whereas addition of bovine prothrombin alone was ineffective. We therefore concluded that those ACA targeted bovine AT once it has been modified/cleaved by thrombin. These findings underline the wide heterogeneity of ACA and the links that may exist between various coagulation pathways, inflammation and the complement system.
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Some Anticardiolipin Antibodies Recognize a Combination of Phospholipids With Thrombin-Modified Antithrombin, Complement C4b-Binding Protein, and Lipopolysaccharide Binding Protein. Blood 1999. [DOI: 10.1182/blood.v93.12.4248] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractThe standard enzyme-linked immunosorbent assay (ELISA) for anticardiolipin antibodies (ACA) detects a heterogenous group of antibodies against cardiolipin on its own, β2-glycoprotein I (β2GPI), and, potentially, other phospholipid-binding plasma proteins from bovine or human origin. In an attempt to identify new proteic targets of ACA, we selected 6 patients who possessed cofactor-dependent ACA but no antibody to human or bovine β2GPI detectable in the β2GPI-ELISA. Three of these samples proved to recognize β2GPI in combination with cardiolipin, but not β2GPI directly immobilized on γ-irradiated polystyrene or agarose beads. In the other cases, the component required for ACA binding was purified from adult bovine serum or plasma by means of ammonium sulfate precipitation and chromatography on Phenyl-Sepharose, diethyl aminoethyl (DEAE)-cellulose, heparin-Ultrogel, and Sephacryl S-300 columns. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis coupled to N-terminal amino acid microsequencing identified the cofactors of patients no. 4, 5, and 6 ACA as lipopolysaccharide binding protein (LBP), complement C4b-binding protein (C4BP), and the thrombin-antithrombin (AT) complex, respectively. Adsorption of each of these cofactor preparations with cardiolipin liposomes led to suppression of ACA reactivity, concomitant with the loss of bands from SDS gels corresponding to sequenced material. Bacterial lipopolysaccharide (which forms high-affinity complexes with LBP) specifically neutralized the cofactor activity of the LBP preparation in a concentration-dependent manner. Bovine serum and plasma, as well as the C4BP preparation, optimally supported the binding of a rabbit anti-C4BP antiserum to immobilized cardiolipin. The binding of a rabbit anti-AT antiserum to solid-phase cardiolipin was sustained by the thrombin-AT preparation and bovine serum, but neither by bovine plasma nor by native AT, thus reproducing the behavior of patient no. 6 ACA. Taking advantage of the restricted recognition by the latter ACA of a cofactor from bovine origin appearing upon clotting, we studied the generation of such activity in human plasma supplemented with bovine AT or bovine prothrombin before clotting. In these conditions, patient no. 6 antibody binding to cardiolipin required the addition of bovine AT, whereas addition of bovine prothrombin alone was ineffective. We therefore concluded that those ACA targeted bovine AT once it has been modified/cleaved by thrombin. These findings underline the wide heterogeneity of ACA and the links that may exist between various coagulation pathways, inflammation and the complement system.
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Villoutreix BO, Blom AM, Webb J, Dahlbäck B. The complement regulator C4b-binding protein analyzed by molecular modeling, bioinformatics and computer-aided experimental design. IMMUNOPHARMACOLOGY 1999; 42:121-34. [PMID: 10408373 DOI: 10.1016/s0162-3109(99)00022-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Molecular modeling and bioinformatics have gained recognition as scientific disciplines of importance in the field of biomedical research. Molecular modeling not only allows to predict the three-dimensional structure of a protein but also helps to define its function. Careful incorporation of the experimental findings in the structural/theoretical data provides means to understand molecular mechanisms for highly complex biological systems. C4b-binding protein (C4BP) is composed of one beta-chain and seven alpha-chains essentially built from three- and eight-complement control protein (CCP) modules, respectively, followed by a non-repeat carboxy-terminal region involved in polymerization of the chains. C4BP is involved in the regulation of the complement system and interacts with many molecules such as C4b, Arp, protein S and heparin. Here, we report experimental and computer data obtained for C4BP. Protein modeling together with site directed mutagenesis indicate that R39, R64 and R66 from the C4BP alpha-chain form a key binding site for heparin, suggesting that this region could be of major importance for interaction with C4b. We also propose that the first CCP of the C4BP beta-chain displays a key hydrophobic surface of major importance for the interaction with the coagulation cofactor protein S.
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Affiliation(s)
- B O Villoutreix
- Lund University, The Wallenberg Laboratory, Department of Clinical Chemistry, University Hospital, Malmö, Sweden.
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Li XA, Yutani C, Shimokado K. Serum amyloid P component associates with high density lipoprotein as well as very low density lipoprotein but not with low density lipoprotein. Biochem Biophys Res Commun 1998; 244:249-52. [PMID: 9514915 DOI: 10.1006/bbrc.1998.8248] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Serum amyloid P component (SAP) is a glycoprotein in human plasma. We previously showed that SAP is specifically localized in human atherosclerotic lesions, suggesting that SAP may play a role in atherogenesis. In this study, the interactions between human SAP and high density lipoprotein (HDL), low density lipoprotein (LDL) and very low density lipoprotein (VLDL) were investigated by using a solid phase plate assay. Biotinylated SAP bound to immobilized HDL and VLDL in a calcium-dependent, saturable manner. The SAP-HDL and SAP-VLDL bindings reached saturation at 4 nM and 16 nM of SAP, respectively. The bindings were inhibited by native SAP in a dose-dependent manner. No binding between SAP and LDL was found in the presence of calcium or EDTA, which indicates the specificity of SAP-lipoproteins interactions. These results suggest that the function of SAP is related to its capability to interact with lipoproteins and this may have important implications in atherosclerosis and in amyloidosis.
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Affiliation(s)
- X A Li
- Department of Biochemistry, Taishan Medical College, Taian, Shandong, P. R. China.
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35
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Yoshidome H, Kuriyama M, Fujiyama J, Osame M. Serum amyloid A and P protein levels are lowered by dextran sulfate cellulose low-density lipoprotein apheresis. Artif Organs 1998; 22:144-8. [PMID: 9491906 DOI: 10.1046/j.1525-1594.1998.05065.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The present study describes the short-term effect of dextran sulfate cellulose (DSC) low-density lipoprotein (LDL) apheresis using a plasma separator equipped with a polysulfone (PS) membrane filter (PS/DSC-LDL apheresis) on the serum amyloid A (SAA) and P (SAP) protein levels during treatment in a patient with familial hypercholesterolemia (type IIa, heterozygote). PS/DSC-LDL apheresis markedly lowered both the SAA (reduction percentage, 84.1+/-8.2%) and SAP (91.4+/-5%) levels, which returned to their respective initial levels within 4 days. Experimentally, the levels of both proteins also decreased on passage through the DSC minicolumn without a PS membrane, indicating that the DSC resin had an affinity to both proteins. These results suggest that PS/DSC-LDL apheresis may be advantageous for amyloid protein accumulating disorders, including amyloidosis and atherosclerosis.
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Affiliation(s)
- H Yoshidome
- The Third Department of Internal Medicine, Kagoshima University School of Medicine, Sakuragaoka, Japan
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36
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Joseph DR. Sequence and functional relationships between androgen-binding protein/sex hormone-binding globulin and its homologs protein S, Gas6, laminin, and agrin. Steroids 1997; 62:578-88. [PMID: 9292933 DOI: 10.1016/s0039-128x(97)00045-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Androgen-binding protein/sex hormone-binding globulin (ABP/SHBG) is an extracellular binding protein that regulates the bioavailability of sex steroids. ABP/SHBG is closely related to the globular (G) domain of vitamin K-dependent protein S family of proteins and more distantly related to the G domains of several extracellular matrix proteins. ABP/SHBG appears to have evolved from the fusion of two ancestral G domains. Expanding evidence suggests that ABP/SHBG has other functions that are mediated through membrane binding, including signal transduction; however, the types of binding proteins (receptors) have not been identified. Sequence comparisons of ABP/SHBG with G domains of its homologs protein S, Gas6, laminin, and agrin have identified regions of ABP/SHBG that may bind receptors related to homolog receptors. These membrane receptors include beta-integrins, alpha-dystroglycan, and receptor tyrosine kinases. The G domains of laminin and related proteins have clearly evolved from a common ancestor to interact with specific receptors and binding proteins. It remains to be determined if ABP/SHBG followed this evolutionary pathway.
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Affiliation(s)
- D R Joseph
- Applied Genetics Laboratories, Inc., University of Florida, Alachua 32615, USA
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37
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Kasuno K, Tsuzuki D, Tanaka A, Ueda S, Sugawara A, Senzaki H, Kuwahara T. A 41-year-old woman with protein S deficiency and diffuse proliferative lupus nephritis: is protein S deficiency associated with a hyperinflammatory response? Am J Kidney Dis 1997; 29:931-5. [PMID: 9186080 DOI: 10.1016/s0272-6386(97)90468-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A 41-year-old woman with complete protein S (PS) deficiency who developed diffuse proliferative lupus nephritis is reported. She was referred to our hospital with nephrotic syndrome and thrombocytopenia. Her medical history included colorectostomy and amputation of the extremities because of repeated thrombotic episodes during her teens without any evidence of systemic lupus erythematosus. The diagnosis of PS deficiency was made from the patient's clinical course, undetectable serum PS in either the active or inactive form, normal protein C activity, and no evidence of the antiphospholipid syndrome. However, there was no definitive family history. A depressed level of complements and a positive antinuclear acid antibody suggested a diagnosis of systemic lupus erythematosus. The patient had a rapidly progressive course and died of disseminated intravascular coagulation. An autopsy showed generalized thrombotic lesions and diffuse proliferative lupus nephritis on both ordinal light and immunoperoxidase microscopy. Our observations suggest that PS-deficient patients may have a hyperinflammatory response.
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Affiliation(s)
- K Kasuno
- Department of Nephrology, Saiseikai Nakatsu Hospital, Osaka, Japan
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38
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Foster JA, Friday BB, Maulit MT, Blobel C, Winfrey VP, Olson GE, Kim KS, Gerton GL. AM67, a secretory component of the guinea pig sperm acrosomal matrix, is related to mouse sperm protein sp56 and the complement component 4-binding proteins. J Biol Chem 1997; 272:12714-22. [PMID: 9139729 DOI: 10.1074/jbc.272.19.12714] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The guinea pig sperm acrosomal matrix is the dense core of the acrosome and is likely to be important in acrosome biogenesis and fertilization. Isolated acrosomal matrices are composed of a limited number of major bands when analyzed by SDS-polyacrylamide gel electrophoresis, among which is a Mr 67,000 protein that we have termed AM67. Indirect immunofluorescence demonstrated that AM67 is localized to the apical segment of the cauda epididymal sperm acrosome. Immunoelectron microscopy further refined the localization of AM67 to the M1 (dorsal bulge) domain within the acrosome. Using a polymerase chain reaction product based upon tryptic peptide sequences from AM67, a lambdagt11 guinea pig testis cDNA library was screened to yield two cDNA clones that encode the AM67 peptides. Northern analysis revealed that AM67 is transcribed as a 1. 9-kilobase testis-specific mRNA. The complete AM67 sequence encodes a prepropolypeptide of 533 amino acids with a calculated Mr of 59, 768. Following cleavage of a probable signal sequence, the polypeptide was predicted to have a Mr of 56,851 and seven consensus sites for asparagine-linked glycosylation. The deduced amino acid sequence of AM67 is most similar to those of the mouse sperm protein sp56 and the alpha-subunits of complement component 4-binding proteins from various mammalian species. Although mouse sp56 has been reported to be a cell-surface receptor for the murine zona pellucida glycoprotein ZP3, standard immunoelectron microscopy using the anti-sp56 monoclonal antibody 7C5 detected sp56 within the mouse sperm acrosome, but failed to detect sp56 on the surface of acrosome-intact mouse sperm. Furthermore, acrosomal labeling was detected in mouse sperm prepared for immunofluorescence using paraformaldehyde fixation, but was not observed with live unfixed sperm. Thus, the finding that sp56 is present within the acrosome provides further support that sp56 and AM67 are orthologues and suggests that sp56 may function in acrosomal matrix-zona pellucida interactions during and immediately following the acrosome reaction in the mouse.
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Affiliation(s)
- J A Foster
- Center for Research on Reproduction and Women's Health, Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia, Pennsylvania 19104-6080, USA
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39
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40
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Goodman AR, Cardozo T, Abagyan R, Altmeyer A, Wisniewski HG, Vilcek J. Long pentraxins: an emerging group of proteins with diverse functions. Cytokine Growth Factor Rev 1996; 7:191-202. [PMID: 8899296 DOI: 10.1016/1359-6101(96)00019-6] [Citation(s) in RCA: 100] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The earliest described pentraxins, C reactive protein (CRP) and serum amyloid P component (SAP), are cytokine-inducible acute phase proteins implicated in innate immunity whose concentrations in the blood increase dramatically upon infection or trauma. The highly conserved family of pentraxins was thought to consist solely of approximately 25 kDa proteins. Recently, several distinct larger proteins have been identified in which only the C-terminal halves show characteristic features of the pentraxin family. One of the recently described "long" pentraxins (TSG-14/PTX3) is inducible by TNF or IL-1 and is produced during the acute phase response. Other newly identified long pentraxins are constitutively expressed proteins associated with sperm-egg fusion (apexin/p50), may function at the neuronal synapse (neuronal pentraxin I, NPI), or may serve yet other, unknown functions (NPII and XL-PXN1). Evidence obtained by molecular modeling and by direct physicochemical analysis suggests that TSG-14 protein retains some characteristic structural features of the pentraxins, including the formation of pentameric complexes.
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Affiliation(s)
- A R Goodman
- Department of Microbiology, Kaplan Cancer Center, New York University Medical Center, NY 10016, USA
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41
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Kinnunen PK. On the molecular-level mechanisms of peripheral protein-membrane interactions induced by lipids forming inverted non-lamellar phases. Chem Phys Lipids 1996. [DOI: 10.1016/0009-3084(96)02579-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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42
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Abstract
The complement system has developed a remarkably simple but elegant manner of regulating itself. It has faced and successfully dealt with how to facilitate activation on a microbe while preventing the same on host tissue. It solved this problem primarily by creating a series of secreted and membrane-regulatory proteins that prevent two highly undesirable events: activation in the fluid phase (no target) and on host tissue (inappropriate target). Also, if not checked, even on an appropriate target, the system would go to exhaustion and have nothing left for the next microbe. Therefore, the complement enzymes have an intrinsic instability and the fluid-phase control proteins play a major role in limiting activation in time. The symmetry of the regulatory process between fluid phase and membrane inhibitors at the C4/C3 step of amplification and convertase formation as well as at the MAC steps are particularly striking features of the self/nonself discrimination system. The use of glycolipid anchored proteins on membranes to decay enzymes and block membrane insertion events is unlikely to be by chance. Finally, it is economical for the cofactor regulatory activity to produce derivatives of C3b that now specifically engage additional receptors. Likewise, C1-Inh leads to C1q remaining on the immune complex to interact with the C1q receptor. Thus the complement system is designed to allow rapid, efficient, unimpeded activation on an appropriate foreign target while regulatory proteins intervene to prevent three undesirable consequences of complement activation: excessive activation on a single target, fluid phase activation, and activation on self.
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Affiliation(s)
- M K Liszewski
- Department of Medicine, Washington University School of Medicine, St Louis, Missouri 63110, USA
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43
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García de Frutos P, Härdig Y, Dahlbäck B. Serum amyloid P component binding to C4b-binding protein. J Biol Chem 1995; 270:26950-5. [PMID: 7592941 DOI: 10.1074/jbc.270.45.26950] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Human C4b-binding protein (C4BP), which is a regulator of the classical complement pathway C3 convertase, forms high affinity complexes with anticoagulant protein S and with the pentraxin serum amyloid P component (SAP). SAP is a plasma protein present in all amyloid deposits. Recently, SAP was shown to inhibit the complement regulatory functions of C4BP. In this investigation, we have studied the structural requirements for the C4BP-SAP interaction. C4BP was subjected to chymotrypsin digestion, which yielded two major fragments corresponding to the central core (160 kDa) and to the cleaved-off tentacles (48 kDa). SAP-Sepharose specifically bound the 160-kDa fragment, suggesting that the central core of C4BP contains the binding site for SAP. In a quantitative affinity chromatography assay, the dissociation constants for binding of intact C4BP and of the 160-kDa central core fragment to SAP were found to be 30 and 70 nM, respectively. Recombinant C4BP composed of only alpha-chains bound SAP with similar affinity (Kd = 22 nM), whereas nonglycosylated recombinant alpha-chain C4BP (synthesized in the presence of tunicamycin) bound SAP with lower affinity (Kd = 126 nM). This suggests that the carbohydrate moiety of the central core of C4BP is important for binding of C4BP to SAP in contrast to the C4BP beta-chain, which is not required. EDTA, heparin, and phosphorylethanolamine as well as a peptide comprising amino acids 27-39 of SAP were found to completely displace C4BP from the SAP matrix. Moreover, the immobilized SAP peptide bound C4BP in a reaction that, in contrast to the C4BP-SAP interaction, was not dependent on calcium.
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Affiliation(s)
- P García de Frutos
- Department of Clinical Chemistry, Lund University, University Hospital Malmö, Sweden
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44
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Janciauskiene S, García de Frutos P, Carlemalm E, Dahlbäck B, Eriksson S. Inhibition of Alzheimer beta-peptide fibril formation by serum amyloid P component. J Biol Chem 1995; 270:26041-4. [PMID: 7592799 DOI: 10.1074/jbc.270.44.26041] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A 39-43-amino acid residue-long fragment (beta-peptide) from the amyloid precursor protein is the predominant component of amyloid deposits in the brain of individuals with Alzheimer's disease. Serum amyloid P component (SAP) is present in all types of amyloid, including that of Alzheimer's disease. We have used an in vitro model to study the effects of purified SAP on the fibril formation of synthetic Alzheimer beta-peptide 1-42. SAP was found to inhibit fibril formation and to increase the solubility of the peptide in a dose-dependent manner. At a 5:1 molar ratio of A beta 1-42 peptide to SAP, fibril formation was completely inhibited, and approximately 80% of the peptide remained in solution even after 4 days of incubation. At lower SAP concentrations, e.g. at peptide to SAP ratio of 1000:1, short fibrillar like structures, lacking amyloid characteristics, were formed. These structures frequently contained associated SAP molecules, suggesting that SAP binds to the polymerizing peptide in a reaction which prevented further fibril formation.
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Affiliation(s)
- S Janciauskiene
- Department of Medicine, Lund University, University Hospital, Malmö, Sweden
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45
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Schwalbe RA, Coe JE, Nelsestuen GL. Association of rat C-reactive protein and other pentraxins with rat lipoproteins containing apolipoproteins E and A1. Biochemistry 1995; 34:10432-9. [PMID: 7544614 DOI: 10.1021/bi00033a015] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
C-Reactive protein (CRP) is a member of the pentraxin family of proteins, ubiquitous components of animal serum. This study suggests that, in serum, rat CRP is complexed with lipoprotein and may interact directly with apolipoprotein E. When mixed with diluted rat serum, radiolabeled rat CRP showed a slightly higher sedimentation coefficient (about 15%) than that of the free protein. Elimination of calcium or addition of O-phosphorylethanolamine (O-PE), a low molecular weight compound that binds tightly to rat CRP in a calcium-dependent manner, abolished this difference. Adsorption of rat serum on a rat CRP affinity gel and elution with PE resulted in the isolation of material containing high levels of apolipoproteins E and A1. The affinity-purified preparation interacted with rat CRP and altered the sedimentation coefficient of the latter to the value observed in whole serum. Conversely, rat CRP increased the sedimentation coefficient of the major component of the affinity-purified material or to diluted rat serum, human serum amyloid P (SAP) and hamster female protein (FP), two other members of the pentraxin protein family, also had slightly higher sedimentation coefficients. In contrast, human CRP showed no evidence of an interaction in rat serum or with the affinity-purified proteins. This selectivity coincided with the ability of these pentraxins to bind to O-PE with high affinity. The sedimentation properties of serum lipoproteins, radiolabeled with [3H]cholesterol, also suggested an interaction with rat CRP.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- R A Schwalbe
- Department of Biochemistry, University of Minnesota, St. Paul 55108, USA
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46
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Coppola R, Tombesi S, Cristilli P, Bergamaschini L, Mannucci PM. Comparison of two immunoassays for the complement protein C4b-binding protein in health and disease. INTERNATIONAL JOURNAL OF CLINICAL & LABORATORY RESEARCH 1995; 25:88-92. [PMID: 7663011 DOI: 10.1007/bf02592363] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
An enzyme-linked immunoassay for human C4b-binding protein (concentration range 25-400 ng/ml) was developed using two monoclonal antibodies; the intra- and interassay coefficients of variation were less than 7.2%. In 50 normal subjects, 20 patients with liver cirrhosis and 34 full-term newborns, the plasma levels of C4b-binding protein were very similar to those measured by Laurell electroimmunoassay; in 24 patients with elevated erythrocyte sedimentation rates, levels measured by enzyme-linked immunoassay were higher then those measured by the Laurell method (270 +/- 70% vs. 223 +/- 67%). In these patients crossed immunoelectrophoresis showed a pattern different from that of normal individuals, which may explain the lower values found with the Laurell method.
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Affiliation(s)
- R Coppola
- Angelo Bianchi Bonomi Haemophilia and Thrombosis Centre, IRCCS Maggiore Hospital, Milan, Italy
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47
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Sørensen IJ, Andersen O, Nielsen EH, Svehag SE. Native human serum amyloid P component is a single pentamer. Scand J Immunol 1995; 41:263-7. [PMID: 7871385 DOI: 10.1111/j.1365-3083.1995.tb03562.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Serum amyloid P component (SAP) and C-reactive protein (CRP) are members of the pentraxin protein family. SAP is the precursor protein to amyloid P component present in all forms of amyloidosis. The prevailing notion is that SAP in circulation has the form of a double pentameric molecule (decamer) whereas CRP is a single pentameric molecule. We have investigated by gel permeation chromatography the M(r) of SAP in freshly collected human serum and of SAP purified by carbohydrate affinity chromatography and anion exchange chromatography. SAP was monitored by quantitative immunoelectrophoresis and ELISA, and SAP peak fractions were analysed by use of SDS-PAGE, Western blotting, and electron microscopy. The results indicate that native SAP circulates as a single pentamer, a part of which forms complexes with C4b-binding protein. The properties of SAP changed during purification as indicated by rocket immunoelectrophoresis and electron microscopy. Thus, electron micrographs of purified SAP showed a predominance of decamers. However, the decamer form of SAP reversed to single pentamers when purified SAP was incorporated into SAP-depleted serum.
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Affiliation(s)
- I J Sørensen
- Department of Medical Microbiology, Odense University, Denmark
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Li XA, Hatanaka K, Ishibashi-Ueda H, Yutani C, Yamamoto A. Characterization of serum amyloid P component from human aortic atherosclerotic lesions. Arterioscler Thromb Vasc Biol 1995; 15:252-7. [PMID: 7749834 DOI: 10.1161/01.atv.15.2.252] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Serum amyloid P component (SAP) is a glycoprotein in human plasma. We recently showed the localization of SAP in human atherosclerotic lesions by immunohistochemical staining. In this study, the presence of SAP in atherosclerotic lesions was confirmed, and the biochemical character of SAP in atherosclerotic intima was investigated and compared with that of native SAP. Atherosclerotic intima was sequentially extracted with 2 mmol/L CaCl2-Tris-buffered saline (TBS), 10 mmol/L EDTA-TBS, 3 mol/L guanidine-TBS, and collagenase digestion. The character of SAP in each extract was studied with double immunodiffusion, electroimmunoassay, crossed immunoelectrophoresis, and Western immunoblotting. The total amount of SAP in atherosclerotic intima was 190 +/- 64 micrograms/g wet tissue with an SAP-albumin ratio of 1:22.7, which is 44 times higher than the relative plasma ratio of 1:1000. This suggests that SAP is specifically localized in atherosclerotic lesions. SAP from the intima was indistinguishable from plasma or purified SAP with respect to immunological character and molecular weight. However, electrophoretic mobility and the binding of SAP to atherosclerotic intima appeared heterogeneous. Of total extractable SAP, about 43% appeared in the CaCl2-TBS fraction, 25% in the EDTA-TBS fraction, and 32% in the collagenase digestion fraction. SAP is one of the two pentraxins in human plasma; the other is C-reactive protein, which has also been reported to locate in atherosclerotic lesions. Our findings suggest a role for SAP in atherogenesis and encourage efforts to determine more precisely the physiological contributions of the pentraxin family to the development of atherosclerosis.
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Affiliation(s)
- X A Li
- Department of Etiology/Pathophysiology, National Cardiovascular Center, Osaka, Japan
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Perlmutter LS, Barrón E, Myers M, Saperia D, Chui HC. Localization of amyloid P component in human brain: vascular staining patterns and association with Alzheimer's disease lesions. J Comp Neurol 1995; 352:92-105. [PMID: 7714241 DOI: 10.1002/cne.903520107] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Amyloid P component is a normal serum protein that is highly conserved across phylogeny. Although it resembles the classic acute-phase reactant C-reactive protein, and is considered to be a normal extracellular matrix component, its physiologic role in humans is unknown. Amyloid P component is also colocalized with accumulations of all recognized forms of amyloid. The present study uses light and electron microscopy to compare the cerebral localization of amyloid P component in cases with (n = 19) and without (n = 15) Alzheimer's disease (AD). In non-AD cases, amyloid P component was predominantly localized to the cerebrovasculature. Perivascular staining was observed in most cases, more so in the white than in the gray matter. In AD cases, amyloid P component was localized to all three characteristics histopathologic lesions, namely, neurofibrillary tangles, senile plaques, and amyloid angiopathy. Furthermore, in cases with prominent staining of gray matter parenchymal lesions, intravascular staining was decreased. Given the fixation and processing methods used, amyloid P component was never seen to be localized to the cerebrovascular basement membrane. These data argue against amyloid P component's postulated role as the anchor for vascular beta-amyloid deposition. Because there is no evidence for intrinsic amyloid P component production in brain, its perivascular and parenchymal distributions suggest either compromise of the blood-brain barrier or transport across vascular endothelium.
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Affiliation(s)
- L S Perlmutter
- Department of Neurology, University of Southern California School of Medicine, Los Angeles 90033
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Affiliation(s)
- B Dahlbäck
- Department of Clinical Chemistry, University of Lund, Malmö General Hospital, Sweden
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