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Kim SJ, Schneidman-Duhovny D, de Groot PG, Urbanus RT, Carter L, de Laat-Kremers R, Weiss TM, Chan MK, Sali A, Rand JH, de Laat B. Identification of thrombosis-related conformational binding epitopes on domain I of β2-glycoprotein I. Thromb Res 2024; 237:145-147. [PMID: 38593525 DOI: 10.1016/j.thromres.2024.03.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 03/15/2024] [Accepted: 03/25/2024] [Indexed: 04/11/2024]
Affiliation(s)
- Seung Joong Kim
- Department of Bioengineering and Therapeutic Sciences, University of California at San Francisco, United States of America; Departments of Physics and Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea
| | - Dina Schneidman-Duhovny
- Department of Bioengineering and Therapeutic Sciences, University of California at San Francisco, United States of America; School of Computer Science and Engineering, Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Philip G de Groot
- Department of Functional Coagulation, Synapse Research Institute, Maastricht, the Netherlands; Department of Clinical Chemistry and Hematology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Rolf T Urbanus
- Department of Clinical Chemistry and Hematology, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Lester Carter
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, United States of America
| | - Romy de Laat-Kremers
- Department of Data Analysis and Artificial Intelligence, Synapse Research Institute, Maastricht, the Netherlands
| | - Thomas M Weiss
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA, United States of America
| | - Man K Chan
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, United States of America
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, University of California at San Francisco, United States of America
| | - Jacob H Rand
- Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, United States of America
| | - Bas de Laat
- Department of Functional Coagulation, Synapse Research Institute, Maastricht, the Netherlands; Department of Data Analysis and Artificial Intelligence, Synapse Research Institute, Maastricht, the Netherlands.
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2
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Lancellotti S, Sacco M, De Cristofaro R. Commentary on "Structural analyses of β2-glycoprotein I: is there a circular conformation?". J Thromb Haemost 2023; 21:3354-3356. [PMID: 38000852 DOI: 10.1016/j.jtha.2023.07.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Accepted: 07/26/2023] [Indexed: 11/26/2023]
Affiliation(s)
- Stefano Lancellotti
- Dipartimento di Diagnostica per Immagini, radioterapia oncologica d Ematologia, Servizio Malattie Emorragiche e Trombotiche, Fondazione Policlinico Universitario "A. Gemell" IRCCS, Roma, Italy
| | - Monica Sacco
- Dipartimento di Diagnostica per Immagini, radioterapia oncologica d Ematologia, Servizio Malattie Emorragiche e Trombotiche, Fondazione Policlinico Universitario "A. Gemell" IRCCS, Roma, Italy; Dipartimento di Medicina e Chirurgia Traslazionale, Università Cattolica S. Cuore, Facoltà di Medicina e Chirurgia "Agostino Gemelli," Roma, Italy
| | - Raimondo De Cristofaro
- Dipartimento di Diagnostica per Immagini, radioterapia oncologica d Ematologia, Servizio Malattie Emorragiche e Trombotiche, Fondazione Policlinico Universitario "A. Gemell" IRCCS, Roma, Italy; Dipartimento di Medicina e Chirurgia Traslazionale, Università Cattolica S. Cuore, Facoltà di Medicina e Chirurgia "Agostino Gemelli," Roma, Italy.
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Buchholz I, McDonnell T, Nestler P, Tharad S, Kulke M, Radziszewska A, Ripoll VM, Schmidt F, Hammer E, Toca-Herrera JL, Rahman A, Delcea M. Specific domain V reduction of beta-2-glycoprotein I induces protein flexibility and alters pathogenic antibody binding. Sci Rep 2021; 11:4542. [PMID: 33633190 PMCID: PMC7907366 DOI: 10.1038/s41598-021-84021-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2020] [Accepted: 02/10/2021] [Indexed: 01/31/2023] Open
Abstract
Beta-2-glycoprotein I (β2GPI) is a blood protein and the major antigen in the autoimmune disorder antiphospholipid syndrome (APS). β2GPI exists mainly in closed or open conformations and comprises of 11 disulfides distributed across five domains. The terminal Cys288/Cys326 disulfide bond at domain V has been associated with different cysteine redox states. The role of this disulfide bond in conformational dynamics of this protein has not been investigated so far. Here, we report on the enzymatic driven reduction by thioredoxin-1 (recycled by Tris(2-carboxyethyl)phosphine; TCEP) of β2GPI. Specific reduction was demonstrated by Western blot and mass spectrometry analyses confirming majority targeting to the fifth domain of β2GPI. Atomic force microscopy images suggested that reduced β2GPI shows a slightly higher proportion of open conformation and is more flexible compared to the untreated protein as confirmed by modelling studies. We have determined a strong increase in the binding of pathogenic APS autoantibodies to reduced β2GPI as demonstrated by ELISA. Our study is relevant for understanding the effect of β2GPI reduction on the protein structure and its implications for antibody binding in APS patients.
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Affiliation(s)
- Ina Buchholz
- Institute of Biochemistry, University of Greifswald, Greifswald, Germany
- ZIK HIKE, University of Greifswald, Greifswald, Germany
| | - Thomas McDonnell
- Division of Biochemical Engineering, Bernard Katz Institute, University College London, London, UK
| | - Peter Nestler
- Institute of Physics, University of Greifswald, Greifswald, Germany
| | - Sudarat Tharad
- Institute for Biophysics, University of Natural Resources and Life Sciences Vienna, Vienna, Austria
| | - Martin Kulke
- Institute of Biochemistry, University of Greifswald, Greifswald, Germany
| | - Anna Radziszewska
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, GOSH, London, UK
- Division of Medicine, Centre for Rheumatology, University College London, London, UK
| | - Vera M Ripoll
- Division of Medicine, Centre for Rheumatology, University College London, London, UK
| | - Frank Schmidt
- Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
- Proteomics Core, Weill Cornell Medicine-Qatar, Doha, Qatar
| | - Elke Hammer
- Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
- DZHK (German Centre for Cardiovascular Research), Partner Site Greifswald, Greifswald, Germany
| | - Jose L Toca-Herrera
- Institute for Biophysics, University of Natural Resources and Life Sciences Vienna, Vienna, Austria
| | - Anisur Rahman
- Division of Medicine, Centre for Rheumatology, University College London, London, UK.
| | - Mihaela Delcea
- Institute of Biochemistry, University of Greifswald, Greifswald, Germany.
- ZIK HIKE, University of Greifswald, Greifswald, Germany.
- DZHK (German Centre for Cardiovascular Research), Partner Site Greifswald, Greifswald, Germany.
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Smalley H, Rowe JM, Nieto F, Zeledon J, Pollard K, Tomich JM, Fleming SD. Beta2 glycoprotein I-derived therapeutic peptides induce sFlt-1 secretion to reduce melanoma vascularity and growth. Cancer Lett 2020; 495:66-75. [PMID: 32891714 PMCID: PMC7899169 DOI: 10.1016/j.canlet.2020.08.039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Revised: 07/11/2020] [Accepted: 08/31/2020] [Indexed: 12/15/2022]
Abstract
Melanoma, a form of skin cancer, is one of the most common cancers in young men and women. Tumors require angiogenesis to provide oxygen and nutrients for growth. Pro-angiogenic molecules such as VEGF and anti-angiogenic molecules such as sFlt-1 control angiogenesis. In addition, the serum protein, Beta2 Glycoprotein I (β2-GPI) induces or inhibits angiogenesis depending on conformation and concentration. β2-GPI binds to proteins and negatively charged phospholipids on hypoxic endothelial cells present in the tumor microenvironment. We hypothesized that peptides derived from the binding domain of β2-GPI would regulate angiogenesis and melanoma growth. In vitro analyses determined the peptides reduced endothelial cell migration and sFlt-1 secretion. In a syngeneic, immunocompetent mouse melanoma model, β2-GPI-derived peptides also reduced melanoma growth in a dose-dependent response with increased sFlt-1 and attenuated vascular markers compared to negative controls. Importantly, administration of peptide with sFlt-1 antibody resulted in tumor growth. These data demonstrate the therapeutic potential of novel β2-GPI-derived peptides to attenuate tumor growth and endothelial migration is sFlt-1 dependent.
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Affiliation(s)
- Haley Smalley
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Jennifer M Rowe
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Fernando Nieto
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Jazmin Zeledon
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - Kellyn Pollard
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - John M Tomich
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS, 66506, USA
| | - Sherry D Fleming
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA.
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5
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Yin D, Chayoua W, Kelchtermans H, de Groot PG, Moore GW, Gris JC, Zuily S, Musial J, de Laat B, Devreese KMJ. Detection of anti-domain I antibodies by chemiluminescence enables the identification of high-risk antiphospholipid syndrome patients: A multicenter multiplatform study. J Thromb Haemost 2020; 18:463-478. [PMID: 31749277 DOI: 10.1111/jth.14682] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 11/06/2019] [Accepted: 11/08/2019] [Indexed: 12/22/2022]
Abstract
BACKGROUND Classification of the antiphospholipid syndrome (APS) relies predominantly on detecting antiphospholipid antibodies (aPLs). Antibodies against a domain I (DI) epitope of anti-β2glycoprotein I (β2GPI) proved to be pathogenic, but are not included in the current classification criteria. OBJECTIVES Investigate the clinical value of detecting anti-DI IgG in APS. PATIENTS/METHODS From eight European centers 1005 patients were enrolled. Anti-cardiolipin (CL) and anti-β2GPI were detected by four commercially available solid phase assays; anti-DI IgG by the QUANTA Flash® β2GPI domain I assay. RESULTS Odds ratios (ORs) of anti-DI IgG for thrombosis and pregnancy morbidity proved to be higher than those of the conventional assays. Upon restriction to patients positive for anti-β2GPI IgG, anti-DI IgG positivity still resulted in significant ORs. When anti-DI IgG was added to the criteria aPLs or used as a substitute for anti-β2GPI IgG/anti-CL IgG, ORs for clinical symptoms hardly improved. Upon removing anti-DI positive patients, lupus anticoagulant remained significantly correlated with clinical complications. Anti-DI IgG are mainly present in high-risk triple positive patients, showing higher levels. Combined anti-DI and triple positivity confers a higher risk for clinical symptoms compared to only triple positivity. CONCLUSIONS Detection of anti-DI IgG resulted in higher ORs for clinical manifestations than the current APS classification criteria. Regardless of the platform used to detect anti-β2GPI/anti-CL, addition of anti-DI IgG measured by QUANTA Flash® did not improve the clinical associations, possibly due to reduced exposure of the pathogenic epitope of DI. Our results demonstrate that anti-DI IgG potentially helps in identifying high-risk patients.
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Affiliation(s)
- Dongmei Yin
- Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, the Netherlands
- Synapse Research Institute, Maastricht, the Netherlands
| | - Walid Chayoua
- Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, the Netherlands
- Synapse Research Institute, Maastricht, the Netherlands
| | - Hilde Kelchtermans
- Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, the Netherlands
- Synapse Research Institute, Maastricht, the Netherlands
| | | | - Gary W Moore
- Viapath Analytics, Department of Haemostasis and Thrombosis, Guy's and St Thomas' Hospitals, London, UK
| | - Jean-Christophe Gris
- Department of Haematology, University Hospital of Nîmes and University of Montpellier, Montpellier, France
- Ivan Sechenov First Moscow State Medical University, Moscow, Russia
| | - Stéphane Zuily
- Inserm, DCAC, Vascular Medicine Division and Regional Competence Center for Rare Vascular and Systemic Autoimmune Diseases, Centre Hospitalier Regional Universitaire de Nancy, Université de Lorraine, Nancy, France
| | - Jacek Musial
- Department of Internal Medicine, Allergy and Immunology, Jagiellonian University Medical College, Kraków, Poland
| | - Bas de Laat
- Cardiovascular Research Institute Maastricht, Maastricht University Medical Center, Maastricht, the Netherlands
- Synapse Research Institute, Maastricht, the Netherlands
| | - Katrien M J Devreese
- Coagulation Laboratory, Department of Laboratory Medicine, Ghent University Hospital, Department of Diagnostic Sciences, Ghent University, Ghent, Belgium
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6
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McDonnell T, Wincup C, Buchholz I, Pericleous C, Giles I, Ripoll V, Cohen H, Delcea M, Rahman A. The role of beta-2-glycoprotein I in health and disease associating structure with function: More than just APS. Blood Rev 2020; 39:100610. [PMID: 31471128 PMCID: PMC7014586 DOI: 10.1016/j.blre.2019.100610] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 08/09/2019] [Accepted: 08/15/2019] [Indexed: 12/22/2022]
Abstract
Beta-2-Glycoprotein I (β2GPI) plays a number of essential roles throughout the body. β2GPI, C-reactive protein and thrombomodulin are the only three proteins that possess the dual capability to up and down regulate the complement and coagulation systems depending upon external stimulus. Clinically, β2GPI is the primary antigen in the autoimmune condition antiphospholipid syndrome (APS), which is typically characterised by pregnancy morbidity and vascular thrombosis. This protein is also capable of adopting at least two distinct structural forms, but it has been argued that several other intermediate forms may exist. Thus, β2GPI is a unique protein with a key role in haemostasis, homeostasis and immunity. In this review, we examine the genetics, structure and function of β2GPI in the body and how these factors may influence its contribution to disease pathogenesis. We also consider the clinical implications of β2GPI in the diagnosis of APS and as a potentially novel therapeutic target.
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Affiliation(s)
- Thomas McDonnell
- Rheumatology, Division of Medicine, Rayne Institute, University College London, UK.
| | - Chris Wincup
- Rheumatology, Division of Medicine, Rayne Institute, University College London, UK
| | - Ina Buchholz
- Nanostructure Group, Institute of Biochemistry, University of Greifswald, Germany
| | - Charis Pericleous
- Imperial College London, Imperial College Vascular Sciences, National Heart & Lung Institute, ICTEM, Hammersmith Campus, Du Cane Road, London, UK
| | - Ian Giles
- Rheumatology, Division of Medicine, Rayne Institute, University College London, UK
| | - Vera Ripoll
- Rheumatology, Division of Medicine, Rayne Institute, University College London, UK
| | - Hannah Cohen
- Department of Haematology, University College London Hospitals NHS Foundation Trust, London, UK
| | - Mihaela Delcea
- Nanostructure Group, Institute of Biochemistry, University of Greifswald, Germany
| | - Anisur Rahman
- Rheumatology, Division of Medicine, Rayne Institute, University College London, UK
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Serrano M, Martinez-Flores JA, Norman GL, Naranjo L, Morales JM, Serrano A. The IgA Isotype of Anti-β2 Glycoprotein I Antibodies Recognizes Epitopes in Domains 3, 4, and 5 That Are Located in a Lateral Zone of the Molecule (L-Shaped). Front Immunol 2019; 10:1031. [PMID: 31134087 PMCID: PMC6515947 DOI: 10.3389/fimmu.2019.01031] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 04/23/2019] [Indexed: 12/21/2022] Open
Abstract
Background: Antiphospholipid syndrome (APS) is characterized by thrombosis and/or pregnancy morbidity with presence of anti-phospholipid antibodies (aPL). The APS classification criteria only consider the aPL of IgG/IgM isotype, however testing of aPL of IgA isotype is recommended when APS is suspected and consensus aPL are negative. IgA anti-βeta-2 glycoprotein-I (B2GP1) has been clearly related with occurrence of thrombotic events. Antibodies anti-B2GP1 of IgG/M isotypes recognize an epitope in Domain 1 (R39-G43), the epitopes that recognize IgA anti-B2GP1 antibodies are not well-identified. Aim: To determine the zones of B2GP1 recognized by antibodies of IgA isotype from patients with APS symptomatology and positive for IgA anti-B2GP1. Methods: IgA antibodies to Domain-1(D1) and Domain-4/5(D4/5) of B2GP1 (ELISA) and epitope mapping on oligopeptide arrays of B2GP1 were evaluated in sera from a group of 93 patients with at least one thrombotic and with isolated positivity for IgA anti-B2GP1 antibodies (negative for other aPL). Results: A total of 47 patients (50.5%) were positive for anti-D4/5 and 23(25%) were positive for anti-D1. When peptide arrays were analyzed, three zones of B2GP1 reactivity were identified for more than 50% of patients. The center of these zones corresponds to amino acids 140(D3), 204(D4), and 264(D5). The peptides recognized on D3 and D4 contain amino acid sequences sharing high homology with proteins of microorganism that were previously related with a possible APS infectious etiology. In the three-dimensional structure of B2GP1, the three peptides, as the R39-G43 epitope, are located on the right side of the molecule (L-shape). The left side (J-shape) does not bind the antibodies. Conclusions: Patients with thrombotic APS clinical-criteria, and isolated IgA anti-B2GP1 positivity appear to preferentially bind, not to the D1 or D4/5 domains of B2GP1, but rather to three sites in D3, D4, and D5. The sites on D3 and D4 were previously described as the target identified by human monoclonal antibodies derived from patients that were capable of inducing APS in animal models. The localization of these epitopes opens a new route to explore to increase understanding of the patholophysiology of the APS and to propose new alternatives and therapeutic targets.
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Affiliation(s)
- Manuel Serrano
- Healthcare Research Institute of Hospital 12 de Octubre, Madrid, Spain
| | | | | | - Laura Naranjo
- Healthcare Research Institute of Hospital 12 de Octubre, Madrid, Spain
| | | | - Antonio Serrano
- Healthcare Research Institute of Hospital 12 de Octubre, Madrid, Spain
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8
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McDonnell TCR, Willis R, Pericleous C, Ripoll VM, Giles IP, Isenberg DA, Brasier AR, Gonzalez EB, Papalardo E, Romay-Penabad Z, Jamaluddin M, Ioannou Y, Rahman A. PEGylated Domain I of Beta-2-Glycoprotein I Inhibits the Binding, Coagulopathic, and Thrombogenic Properties of IgG From Patients With the Antiphospholipid Syndrome. Front Immunol 2018; 9:2413. [PMID: 30405613 PMCID: PMC6204385 DOI: 10.3389/fimmu.2018.02413] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 09/28/2018] [Indexed: 01/08/2023] Open
Abstract
APS is an autoimmune disease in which antiphospholipid antibodies (aPL) cause vascular thrombosis and pregnancy morbidity. In patients with APS, aPL exert pathogenic actions by binding serum beta-2-glycoprotein I (β2GPI) via its N-terminal domain I (DI). We previously showed that bacterially-expressed recombinant DI inhibits biological actions of IgG derived from serum of patients with APS (APS-IgG). DI is too small (7 kDa) to be a viable therapeutic agent. Addition of polyethylene glycol (PEGylation) to small molecules enhances the serum half-life, reduces proteolytic targeting and can decrease immunogenicity. It is a common method of tailoring pharmacokinetic parameters and has been used in the production of many therapies in the clinic. However, PEGylation of molecules may reduce their biological activity, and the size of the PEG group can alter the balance between activity and half-life extension. Here we achieve production of site-specific PEGylation of recombinant DI (PEG-DI) and describe the activities in vitro and in vivo of three variants with different size PEG groups. All variants were able to inhibit APS-IgG from: binding to whole β2GPI in ELISA, altering the clotting properties of human plasma and promoting thrombosis and tissue factor expression in mice. These findings provide an important step on the path to developing DI into a first-in-class therapeutic in APS.
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Affiliation(s)
- Thomas C. R. McDonnell
- Division of Medicine, Centre for Rheumatology Research, University College London, London, United Kingdom
| | - Rohan Willis
- Internal Medicine, University of Texas Medical Branch, Galveston, TX, United States
| | - Charis Pericleous
- Division of Medicine, Centre for Rheumatology Research, University College London, London, United Kingdom
| | - Vera M. Ripoll
- Division of Medicine, Centre for Rheumatology Research, University College London, London, United Kingdom
| | - Ian P. Giles
- Division of Medicine, Centre for Rheumatology Research, University College London, London, United Kingdom
| | - David. A. Isenberg
- Division of Medicine, Centre for Rheumatology Research, University College London, London, United Kingdom
- Arthritis Research UK Centre for Adolescent Rheumatology, UCL/UCLH/Great Ormond Street Hospital, London, United Kingdom
| | - Allan R. Brasier
- Internal Medicine, University of Texas Medical Branch, Galveston, TX, United States
| | - Emilio B. Gonzalez
- Internal Medicine, University of Texas Medical Branch, Galveston, TX, United States
| | - Elizabeth Papalardo
- Internal Medicine, University of Texas Medical Branch, Galveston, TX, United States
| | - Zurina Romay-Penabad
- Internal Medicine, University of Texas Medical Branch, Galveston, TX, United States
| | - Mohammad Jamaluddin
- Internal Medicine, University of Texas Medical Branch, Galveston, TX, United States
| | - Yiannis Ioannou
- Division of Medicine, Centre for Rheumatology Research, University College London, London, United Kingdom
- Arthritis Research UK Centre for Adolescent Rheumatology, UCL/UCLH/Great Ormond Street Hospital, London, United Kingdom
| | - Anisur Rahman
- Division of Medicine, Centre for Rheumatology Research, University College London, London, United Kingdom
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9
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Weaver JC, Krilis SA, Giannakopoulos B. Oxidative post-translational modification of βeta 2-glycoprotein I in the pathophysiology of the anti-phospholipid syndrome. Free Radic Biol Med 2018; 125:98-103. [PMID: 29604397 DOI: 10.1016/j.freeradbiomed.2018.03.048] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Revised: 03/23/2018] [Accepted: 03/28/2018] [Indexed: 12/13/2022]
Abstract
The anti-phospholipid syndrome (APS) is a prothrombotic autoimmune disorder characterized by either thrombosis or pregnancy complications in the setting of persistent anti-phospholipid antibodies (aPL). βeta 2-glycoprotein I (β2-GPI) is the major autoantigen in APS that binds anionic phospholipids as well as specific receptors on platelets and endothelial cells resulting in activation of prothrombotic pathways. β2-GPI consists of 5 Domains that exist in a circular or linear form, with the latter occurring after binding to anionic phospholipids. β2-GPI also undergoes dynamic posttranslational modification between oxidized and free thiol forms. The relationship between posttranslational modification and structural conformation is yet to be definitively clarified. Compared with controls, patients with the APS have higher levels of total β2-GPI and lower levels of free thiol β2-GPI. This raises the possibility of using quantification of β2-GPI posttranslational modification as a redox biomarker in the management and diagnosis of the APS.
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Affiliation(s)
- James C Weaver
- Department of Cardiology, St George Hospital, Sydney, Australia; Department of Medicine, University of NSW, Sydney, Australia
| | - Steven A Krilis
- Department of Medicine, University of NSW, Sydney, Australia; Department of Infectious Diseases, Immunology and Sexual Health, St George Hospital, Sydney, Australia
| | - Bill Giannakopoulos
- Department of Medicine, University of NSW, Sydney, Australia; Department of Infectious Diseases, Immunology and Sexual Health, St George Hospital, Sydney, Australia; Department of Rheumatology, St George Hospital, Sydney, Australia.
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10
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Abstract
Antiphospholipid (aPL) antibodies bind to 2glycoprotein I (2GPI) and cause endothelial cell (EC) activation and thrombosis in mice. 2GPI binds to EC through its Vth domain and induces their activation. TIFI is a 20 amino acid synthetic peptide that shares similarity with the Vth domain of 2GPI. Our objectives were to examine the ability of TIFI to affect aPL-mediated thrombosis in mice and the interactions of TIFI, 2GPI with phospholipid surfaces and target cells. CD1 mice were injected with IgG from a patient with antiphospholipid syndrome (IgG-APS) or with control IgGNHS and with either TIFI or with control peptide (VITT). Size of induced thrombi was determined. Inhibition and competition studies were done using aPL antibodies, cardiolipin (CL) liposomes in the presence of varying amounts of TIFI and 2GPI. Binding of fluorescinated 2GPI to human ECs and to murine macrophages in the presence or absence of TIFI, was also examined. TIFI significantly decreased thrombus size in mice injected with IgG-APS. TIFI reverted the 2GPI-dependent binding of aPL antibodies to CL liposomes in a dose-dependent fashion. This effect was abrogated by addition of 2GPI, suggesting that TIFI displaces the binding of 2GPI to phospholipids. TIFI inhibited the binding of fluorescinated 2GPI to human EC and to murine macrophages. The data indicate that TIFI abrogates thrombogenic properties of aPL in mice by competing with 2GPI and preventing its binding to target cells. This may be important in designing new modalities for the treatment of thrombosis in APS.
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Affiliation(s)
- M Vega Ostertag
- Department of Microbiology, Biochemistry, and Immunology, Morehouse School of Medicine, Atlanta, GA 30310-1495, USA
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11
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Marchetti T, de Moerloose P, Gris JC. Antiphospholipid antibodies and the risk of severe and non-severe pre-eclampsia: the NOHA case-control study. J Thromb Haemost 2016; 14:675-84. [PMID: 26782635 DOI: 10.1111/jth.13257] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 11/25/2015] [Indexed: 12/13/2022]
Abstract
BACKGROUND pre-eclampsia (PEecl) can be defined as non-severe (NS-PEecl) or severe (S-PEecl). Our study aimed to determine the incidence of antiphospholipid antibodies (aPLs) in women with a past history of NS-PEecl or S-PEecl. PATIENTS AND METHODS This case-control study includes 195 control women, 199 NS-PEecl patients and 143 S-PEecl patients whose plasma samples were collected 6 months after their first delivery. Each plasma was tested for lupus anticoagulant (LA), anticardiolipin (aCL) and antiβ2GP1 antibodies, as well as antibodies against phosphatidylserine/prothrombin complex (aPS/PT) and domain I of the β2GP1. RESULTS When compared with the control group no significant associations were found for the NS-PEecl group after adjustment of confounding variables. For the S-PEecl group, there was an association with antiβ2GP1 immunoglobulin G (IgG) (OR 16.91, 95% CI 3.71-77.06), as well as age, obesity, smoking and multiparity. Antiβ2GP1-domain I IgG was associated with aCL, antiβ2GP1 and aPS/PT IgG in the three groups. aPS/PT IgG was associated with aCL IgG, and aPS/PT IgM was associated with aCL and antiβ2GP1 IgM in the three groups. CONCLUSION S-PEecl is a distinct entity from NS-PEecl and is mainly associated with the presence of antiβ2GP1 IgG. Antiβ2GP1 domain I correlates with other aPL IgG tests, and aPS/PT may be promising in patients for whom LA tests cannot be interpreted.
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Affiliation(s)
- T Marchetti
- Haemostasis Unit, University Hospitals and Faculty of Medicine of Geneva, Geneva, Switzerland
| | - P de Moerloose
- Haemostasis Unit, University Hospitals and Faculty of Medicine of Geneva, Geneva, Switzerland
| | - J C Gris
- Laboratoire et Consultations d'Hématologie, CHU Nîmes, Nîmes, France
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12
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Artenjak A, Locatelli I, Brelih H, Simonič DM, Ulcova-Gallova Z, Swadzba J, Musial J, Iwaniec T, Stojanovich L, Conti F, Valesini G, Avčin T, Cohen Tervaert JW, Shoenfeld Y, Blank M, Ambrožič A, Sodin-Semrl S, Božič B, Čučnik S. Immunoreactivity and avidity of IgG anti-β2-glycoprotein I antibodies from patients with autoimmune diseases to different peptide clusters of β2-glycoprotein I. Immunol Res 2015; 61:35-44. [PMID: 25395339 DOI: 10.1007/s12026-014-8578-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The pathogenicity of antibodies against β2-glycoprotein I (anti-β2GPI) depends on multiple factors such as subclass type, epitope binding and avidity. Due to their large heterogeneity, their impact on antiphospholipid syndrome (APS) onset is still not fully clarified. We studied the binding characteristics of IgG anti-β2GPI with known avidity from sera of 201 autoimmune patients (87 with APS, 67 with APS associated with systemic lupus erythematosus (SLE), 47 with only SLE) to six β2GPI peptides corresponding to amino acid clusters on domains I-II, II, III and III-IV by indirect ELISA and evaluated their association with clinical features of APS. Peptides A (LKTPRV; domain I-II), B (KDKATF; domain IV) and C (TLRVYK; domain III) were derived from a hexapeptide phage display library previously shown to react with pathogenic monoclonal anti-β2GPI. Peptides D (NGPANSK; domain III), E (YNPLWFV; domain II) and F (KMDGNHP; domain III-IV) represent surface amino acid clusters on β2GPI. The percentage of patients positive for peptides were observed as follows: 30.3% for peptide D, 28.90% for B, 25.9% for C, 24.9% for E, 24.4% for F and 10.0% for A. The anti-peptide antibodies in studied serum samples were predominantly of heterogeneous avidity, followed by law avidity anti-peptide antibodies, whereas only a few were of high avidity. Positive and negative correlations were found between several anti-peptide antibodies and the rate of thrombosis. Our results indicated diverse reactivity of IgG anti-β2GPI to different epitopes on β2GPI. Classification of IgG anti-β2GPI into subgroups regarding epitope specificity and avidity could represent an additional tool in understanding their pathogenicity in APS.
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Affiliation(s)
- A Artenjak
- Lek Pharmaceuticals d.d., Sandoz Biopharmaceuticals Mengeš, Kolodvorska 27, 1234, Menges, Slovenia
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13
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Maity A, Macaubas C, Mellins E, Astakhova K. Synthesis of Phospholipid-Protein Conjugates as New Antigens for Autoimmune Antibodies. Molecules 2015; 20:10253-63. [PMID: 26046322 PMCID: PMC6272759 DOI: 10.3390/molecules200610253] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 05/27/2015] [Accepted: 05/28/2015] [Indexed: 12/24/2022] Open
Abstract
Copper(I)-catalyzed azide-alkyne cycloaddition, or CuAAC click chemistry, is an efficient method for bioconjugation aiming at chemical and biological applications. Herein, we demonstrate how the CuAAC method can provide novel phospholipid-protein conjugates with a high potential for the diagnostics and therapy of autoimmune conditions. In doing this, we, for the first time, covalently bind via 1,2,3-triazole linker biologically complementary molecules, namely phosphoethanol amine with human β2-glycoprotein I and prothrombin. The resulting phospholipid-protein conjugates show high binding affinity and specificity for the autoimmune antibodies against autoimmune complexes. Thus, the development of this work might become a milestone in further diagnostics and therapy of autoimmune diseases that involve the production of autoantibodies against the aforementioned phospholipids and proteins, such as antiphospholipid syndrome and systemic lupus erythematosus.
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Affiliation(s)
- Arindam Maity
- Nucleic Acid Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, Odense 5230, Denmark.
- Dr. B C Roy College of Pharmacy and AHS, Durgapur, West Bengal 713212, India.
| | - Claudia Macaubas
- Divisions of Human Gene Therapy and Pediatric Rheumatology, Program in Immunology, Stanford University School of Medicine, 269 Campus Drive, Stanford, MC 5164, USA.
| | - Elizabeth Mellins
- Divisions of Human Gene Therapy and Pediatric Rheumatology, Program in Immunology, Stanford University School of Medicine, 269 Campus Drive, Stanford, MC 5164, USA.
| | - Kira Astakhova
- Nucleic Acid Center, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, Odense 5230, Denmark.
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14
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Pelkmans L, Kelchtermans H, de Groot PG, Zuily S, Regnault V, Wahl D, Pengo V, de Laat B. Variability in exposure of epitope G40-R43 of domain i in commercial anti-beta2-glycoprotein I IgG ELISAs. PLoS One 2013; 8:e71402. [PMID: 23951154 PMCID: PMC3741166 DOI: 10.1371/journal.pone.0071402] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 06/27/2013] [Indexed: 01/22/2023] Open
Abstract
Background A major problem for diagnosing the antiphospholipid syndrome (APS) is the high variability between commercial anti-β2glycoprotein I (β2GPI) assays. Predominantly antibodies reactive against cryptic epitope Glycine40-Arginine43 (G40-R43) in domain I are associated with an increased risk for thrombosis. Upon interaction with anionic surfaces β2GPI opens up, thereby exposing G40-R43. Objectives To examine whether suboptimal exposure of epitope G40-R43 explains the variations in results observed between commercial assays. Methods Two patient-derived monoclonal antibodies were tested on neutral versus anionic plates. Antibody P1-117 reacts with G40-R43 in the open conformation while P2-6 recognizes β2GPI irrespective of its conformation. These antibodies were tested in commercial anti-β2GPI assays (A–E). Results In assay A, both antibodies showed equal reactivity towards β2GPI, indicating that all the β2GPI exposes G40-R43. In other assays P1-117 displayed lower reactivity than P2-6, demonstrating reduced G40-R43 availability. To exclude influences of other assay features, reactivity was re-examined on plates of assay A and B using the protocol/reagents from each assay. In all combinations, reactivity of both antibodies on a plate was comparable to results obtained with its own protocol/reagents, suggesting that the coating, rather than other assay components, accounts for the observed differences. In two patient cohorts we demonstrated that a number of domain I-reactive samples are missed in assays characterized by a decreased exposure of epitope G40-R43. Conclusions Exposure of epitope G40-R43 on β2GPI is highly variable between commercial anti-β2GPI assays. As a consequence, patients can be falsely assigned negative in assays characterized by a reduced exposure of G40-R43.
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Affiliation(s)
- Leonie Pelkmans
- Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, The Netherlands
- Synapse BV, Maastricht, The Netherlands
| | - Hilde Kelchtermans
- Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, The Netherlands
- Synapse BV, Maastricht, The Netherlands
- * E-mail:
| | - Philip G. de Groot
- Department of Clinical Chemistry and Haematology, University Medical Centre Utrecht, Utrecht, The Netherlands
| | - Stephane Zuily
- Vascular Medicine Division, Regional Competence Centre for Rare Vascular Diseases, CHU de Nancy, Nancy, France
- INSERM U1116, Université de Lorraine, Nancy, France
| | | | - Denis Wahl
- Vascular Medicine Division, Regional Competence Centre for Rare Vascular Diseases, CHU de Nancy, Nancy, France
- INSERM U1116, Université de Lorraine, Nancy, France
| | - Vittorio Pengo
- Clinical Cardiology, Department of Cardiothoracic and Vascular Sciences, Thrombosis Centre, University of Padua, Padua, Italy
| | - Bas de Laat
- Cardiovascular Research Institute Maastricht, Maastricht University Medical Centre, Maastricht, The Netherlands
- Synapse BV, Maastricht, The Netherlands
- Department of Clinical Chemistry and Haematology, University Medical Centre Utrecht, Utrecht, The Netherlands
- Sanquin Research, Amsterdam, The Netherlands
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15
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Pengo V, Ruffatti A, Del Ross T, Tonello M, Cuffaro S, Hoxha A, Banzato A, Bison E, Denas G, Bracco A, Padayattil Jose S. Confirmation of initial antiphospholipid antibody positivity depends on the antiphospholipid antibody profile. J Thromb Haemost 2013; 11:1527-31. [PMID: 23601766 DOI: 10.1111/jth.12264] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Indexed: 11/27/2022]
Abstract
BACKGROUND The revised classification criteria for the antiphospholipid syndrome state that antiphospholipid (aPL) antibodies (lupus anticoagulant [LAC] and/or anticardiolipin [aCL] and/or anti-β2 -glycoprotein I [aβ2 GPI] antibodies) should be detected on two or more occasions at least 12 weeks apart. Consequently, classification of patient risk and adequacy of treatment may be deferred by 3 months. OBJECTIVES In order to early classify patient risk, we evaluated whether aPL positivity confirmation is related to aPL antibody profiles. PATIENTS AND METHODS Consecutive patients referred to our center who were initially positive in one or more tests exploring the presence of aPL were tested after 3 months. During a 4-year period, 225 patients were initially positive in one or more tests, and 161 were available for confirmation after 3 months. Patients were classified as triple-positive (n = 54: LAC(+) , aCL(+) , aβ2 GPI(+) , same isotype), double-positive (n = 50: LAC(-) , aCL(+) , aβ2 GPI(+) , same isotype) and single-positive (n = 53: LAC or aCL or aβ2 GPI antibodies as the sole positive test). RESULTS Among subjects with triple positivity at initial testing, 98% (53 of 54) had their aPL profile confirmed after 12 weeks. The double-positive and single-positive groups had data confirmed in 42 of 50 (84%) and 23 of 57 (40%) subjects, respectively. CONCLUSIONS Our results show that high-risk subjects with triple-positive aPL profiles are identified early, at the time of the initial screening tests.
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Affiliation(s)
- V Pengo
- Clinical Cardiology, Thrombosis Center, Department of Cardiac Thoracic and Vascular Sciences, University of Padua, Padua, Italy.
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16
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Kolyada A, De Biasio A, Beglova N. Identification of the binding site for fondaparinux on Beta2-glycoprotein I. Biochim Biophys Acta 2013; 1834:2080-8. [PMID: 23811002 DOI: 10.1016/j.bbapap.2013.06.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 06/06/2013] [Accepted: 06/15/2013] [Indexed: 11/17/2022]
Abstract
Antiphospholipid syndrome (APS) is an autoimmune disease with clinical manifestations of thrombosis and pregnancy complications. Beta2-glycoprotein I (β2GPI) is the major antigen for the APS-related antibodies. Heparin, low-molecular weight heparin and the synthetic pentasaccharide fondaparinux are commonly used for prophylaxis and treatment of thrombosis in patients with antiphospholipid syndrome. These antithrombotic drugs bind and activate antithrombin III to inactivate blood clotting proteases. Heparin and heparin derivatives might have a direct beneficial effect in APS via binding to β2GPI and interfering with prothrombotic properties of β2GPI/antibody complexes. We compared fondaparinux to heparin regarding its ability to bind β2GPI and inhibit the binding of β2GPI/antibody complexes to negatively charged phospholipids and endothelial cells. Although heparin and fondaparinux bind β2GPI at therapeutically relevant doses, neither fondaparinux nor heparin was efficient in inhibition of the binding of β2GPI/antibody complexes to negatively charged phospholipids and endothelial cells. Our studies suggest that these drugs do not act on pathological properties of β2GPI/antibody complexes, emphasizing the need for a new treatment specific for β2GPI-related thrombosis in APS. We observed that the binding interface of fondaparinux on β2GPI does not include the lysine residues known to be critical for binding of heparin. The docking model of the β2GPI complex with fondaparinux is in agreement with multiple experimental observations.
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Affiliation(s)
- Alexey Kolyada
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
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17
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Pozzi N, Acquasaliente L, Frasson R, Cristiani A, Moro S, Banzato A, Pengo V, Scaglione GL, Arcovito A, De Cristofaro R, De Filippis V. β2 -Glycoprotein I binds to thrombin and selectively inhibits the enzyme procoagulant functions. J Thromb Haemost 2013; 11:1093-102. [PMID: 23578283 DOI: 10.1111/jth.12238] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Indexed: 08/31/2023]
Abstract
BACKGROUND This work was aimed at characterizing the interaction of β(2)-glycoprotein I (β(2)GPI), an abundant plasma protein of unknown function, with human thrombin, the final effector protease in the coagulation cascade. METHODS The β(2)GPI-thrombin interaction was studied by surface plasmon resonance (SPR), fluorescence, and molecular modeling. The effect of β(2)GPI on the procoagulant (fibrin generation and platelet aggregation) and anticoagulant (protein C activation) functions of thrombin were investigated with turbidimetric, immunocytofluorimetric and enzymatic assays. RESULTS SPR and fluorescence data indicated that β(2)GPI tightly bound thrombin (K(d) = 34 nM) by interacting with both protease exosites, while leaving the active site accessible. This picture is fully consistent with the theoretical model of the β(2)GPI-thrombin complex. In particular, blockage of thrombin exosites with binders specific for exosite-1 (hirugen and HD1 aptamer) or exosite-2 (fibrinogen γ'-peptide and HD22 aptamer) impaired the β2 GPI-thrombin interaction. Identical results were obtained with thrombin mutants having one of the two exosites selectively compromised by mutation (Arg73Ala and Arg101Ala). Fluorescence measurements indicated that β(2)GPI did not affect the affinity of the enzyme for active site inhibitors, such as p-aminobenzamidine and the hirudin(1-47) domain, in agreement with the structural model. β(2)GPI dose-dependently prolonged the thrombin clotting time and ecarin clotting time in β(2)GPI-deficient plasma. β(2)GPI inhibited thrombin-induced platelet aggregation (IC50 = 0.36 μM) by impairing thrombin cleavage of protease-activated receptor 1 (PAR1) (IC50 = 0.32 μM), both on gel-filtered platelets and in whole blood. Strikingly, β(2) GPI did not affect thrombin-mediated generation of the anticoagulant protein C. CONCLUSIONS β(2) GPI functions as a physiologic anticoagulant by inhibiting the key procoagulant activities of thrombin without affecting its unique anticoagulant function.
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Affiliation(s)
- N Pozzi
- Laboratory of Protein Chemistry, School of Medicine, University of Padua, Padova, Italy
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18
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Abstract
The information covered in this chapter will present a model homogenous membrane preparation technique and dynamic imaging procedure that can be successfully applied to more than one type of lipid study and atomic force microscope (AFM) instrument setup. The basic procedural steps have been used with an Asylum Research MFP-3D BIO and the Bruker (formerly, Veeco) BioScope. The AFM imaging protocol has been supplemented by procedures (not to be presented in this chapter) of ellipsometry, standardized western blotting, and dot-blots to verify appropriate purity and activity of all experimental molecular components; excellent purity and activity level of the lipids, proteins, and drug(s) greatly influence the success of imaging experiments in the scanning probe microscopy field. The major goal of the chapter is to provide detailed procedures for sample preparation and operation of the Asylum Research MFP-3D BIO AFM. In addition, one should be cognizant that our comprehensive description in the use of the MFP-3D BIO's functions for successful image acquisitions and analyses is greatly enhanced by Asylum Research's (AR's) accompanying extensive manual(s), technical notes, and AR's users forum. Ultimately, the stepwise protocol and information will allow novice personnel to begin acquiring quality images for processing and analysis with minimal supervision.
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Affiliation(s)
- Anthony S Quinn
- Department of Pathology and Microscopy Imaging Center, College of Medicine, University of Vermont, Burlington, VT, USA.
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19
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Schlichtiger A, Baier C, Yin MX, Holmes AB, Maruyama M, Strasser R, Rant U, Thaler M, Luppa PB. Covalent attachment of functionalized cardiolipin on a biosensor gold surface allows repetitive measurements of anticardiolipin antibodies in serum. Anal Bioanal Chem 2012; 405:275-85. [PMID: 23090649 DOI: 10.1007/s00216-012-6467-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 09/18/2012] [Accepted: 09/28/2012] [Indexed: 11/26/2022]
Abstract
Antiphospholipid antibodies (aPL) are a relevant serological indicator of antiphospholipid syndrome (APS). A solid-state surface with covalently bound ω-amine-functionalized cardiolipin was established and the binding of β2-glycoprotein I (β2-GPI) was investigated either by use of surface plasmon resonance (SPR) biosensor, by electrically switchable DNA interfaces (switchSENSE) and by scanning tunneling microscopy (STM). STM could clearly visualize the attachment of β2-GPI to the cardiolipin surface. Using the switchSENSE sensor, β2-GPI as specific ligand could be identified by increased hydrodynamic friction. The binding of anti-cardiolipin antibodies (aCL) was detected against the ω-amine-functionalized cardiolipin-modified SPR biosensor (aCL biosensor) using sera from healthy donors, APS patients and syphilis patients. Our results showed that the aCL biosensor is a much more sensitive diagnostic device for APS patients compared to previous methods. The specificity between β2-GPI-dependent autoimmune- and β2-GPI-independent infection-associated types of aPLs was also studied and they can be distinguished by the different binding kinetics and patterns.
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Affiliation(s)
- Alice Schlichtiger
- Institut für Klinische Chemie und Pathobiochemie, Klinikum rechts der Isar der Technischen Universität München, Ismaninger Strasse 22, 81675 Munich, Germany.
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20
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de la Torre YM, Pregnolato F, D’Amelio F, Grossi C, DiSimone N, Pasqualini F, Nebuloni M, Chen P, Pierangeli S, Bassani N, Ambrogi F, Borghi MO, Vecchi A, Locati M, Meroni PL. Anti-phospholipid induced murine fetal loss: novel protective effect of a peptide targeting the β2 glycoprotein I phospholipid-binding site. Implications for human fetal loss. J Autoimmun 2012; 38:J209-15. [PMID: 22196923 PMCID: PMC3313005 DOI: 10.1016/j.jaut.2011.11.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Revised: 11/21/2011] [Accepted: 11/22/2011] [Indexed: 10/14/2022]
Abstract
β2 glycoprotein I (β2GPI)-dependent anti-phospholipid antibodies (aPL) induce thrombosis and affect pregnancy. The CMV-derived synthetic peptide TIFI mimics the PL-binding site of β2GPI and inhibits β2GPI cell-binding in vitro and aPL-mediated thrombosis in vivo. Here we investigated the effect of TIFI on aPL-induced fetal loss in mice. TIFI inhibitory effect on in vitro aPL binding to human trophoblasts was evaluated by indirect immunofluorescence and ELISA. TIFI effect on aPL-induced fetal loss was investigated in pregnant C57BL/6 mice treated with aPL or normal IgG (NHS). Placenta/fetus weight and histology and RNA expression were analyzed. TIFI, but not the control peptide VITT, displayed a dose-dependent inhibition of aPL binding to trophoblasts in vitro. Injection of low doses of aPL at day 0 of pregnancy caused growth retardation and increased fetal loss rate, both significantly reduced by TIFI but not VITT. Consistent with observations in humans, histological analysis showed no evidence of inflammation in this model, as confirmed by the absence of an inflammatory signature in gene expression analysis, which in turn revealed a TIFI-dependent modulation of molecules involved in differentiation and development processes. These findings support the non-inflammatory pathogenic role of aPL and suggest innovative therapeutic approaches to aPL-dependent fetal loss.
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Affiliation(s)
| | | | - Fabio D’Amelio
- Department of Internal Medicine, University of Milan, Italy
| | | | | | | | - Manuela Nebuloni
- L. Sacco Department of Medical Science, University of Milan, Italy
| | - Pojen Chen
- Department of Medicine, University of Los Angeles, CA -USA
| | - Silvia Pierangeli
- Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX - USA
| | | | | | - Maria-Orietta Borghi
- Istituto Auxologico Italiano, Milan, Italy
- Department of Internal Medicine, University of Milan, Italy
| | | | - Massimo Locati
- Istituto Clinico Humanitas, Rozzano, Italy
- Department of Translational Medicine, University of Milan, Italy
| | - Pier-Luigi Meroni
- Istituto Auxologico Italiano, Milan, Italy
- Department of Internal Medicine, University of Milan, Italy
- Istituto G. Pini, Milan, Italy
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21
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Pericleous C, Miles J, Esposito D, Garza-Garcia A, Driscoll PC, Lambrianides A, Latchman D, Isenberg D, Rahman A, Ioannou Y, Giles I. Evaluating the conformation of recombinant domain I of β(2)-glycoprotein I and its interaction with human monoclonal antibodies. Mol Immunol 2011; 49:56-63. [PMID: 21899894 PMCID: PMC3268385 DOI: 10.1016/j.molimm.2011.07.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 07/27/2011] [Accepted: 07/27/2011] [Indexed: 11/29/2022]
Abstract
Pathogenic antiphospholipid antibodies (aPL) cause the antiphospholipid syndrome (APS) by interacting with domain I (DI) of beta-2-glycoprotein I (β2GPI). The aPL/β2GPI complex then exerts pathogenic effects on target cells. We previously described periplasmic bacterial expression of native and mutated variants of DI, and reported the presence of immunodominant epitopes at positions 8–9 (D8/D9) and position 39 (R39). Mutations at these positions strongly influenced the ability of recombinant DI to bind patient-derived IgG aPL and to inhibit pathogenic effects of these aPL in a mouse model of APS. We now describe an improved cytoplasmic bacterial expression system allowing higher yield of DI. We demonstrate that the nuclear magnetic resonance (NMR) spectra of a 15N,13C-isotope-labelled sample of the recombinant DI protein exhibit properties consistent with the structure of DI in crystal structure of intact β2GPI. Mutations at D8/D9 and R39 had limited impact on the NMR spectrum of DI indicating maintenance of the overall fold of the DI domain. We investigated interactions between five variants of DI and ten monoclonal human IgG antibodies, all derived from the IgG aPL antibody IS4 by sequence manipulation and in vitro expression. Arginine residues at positions 100 and 100g in IS4VH CDR3 play a particularly important role in binding to DI, but this is unlikely to be due to electrostatic interactions with negatively charged amino acids on DI. Both the strength of binding to DI and the ability to discriminate different DI variants varies between the different IgG antibodies tested. There was no simple relationship between these binding properties and antibody pathogenicity.
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Affiliation(s)
- Charis Pericleous
- Centre for Rheumatology, Division of Medicine, University College London, London WC1E 6JF, UK.
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22
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Abstract
β(2) -Glycoprotein I (β(2) -GPI) is a protein that circulates in blood at high concentrations. The function of β(2) -GPI has long been an enigma. More than 20 years ago, it was discovered that β(2) -GPI is the major antigen for the circulating antibodies in the antiphospholipid syndrome. However, this knowledge has not advanced our understanding of the physiologic role of the protein. In recent years, new insights have suggested an important function of this protein in innate immunity. β(2) -GPI was found to scavenge lipopolysaccharide and was able to clear unwanted anionic cellular remnants such as microparticles from the circulation. The function of β(2) -GPI seems to depend on the structural conformation of the protein, and it has been established that β(2) -GPI can exist in at least two conformations. In this review, we will highlight and summarize the current knowledge on this protein.
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Affiliation(s)
- P G de Groot
- Department of Clinical Chemistry and Hematology, University Medical Center, Utrecht, the Netherlands.
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Kolyada A, Lee CJ, De Biasio A, Beglova N. A novel dimeric inhibitor targeting Beta2GPI in Beta2GPI/antibody complexes implicated in antiphospholipid syndrome. PLoS One 2010; 5:e15345. [PMID: 21179511 PMCID: PMC3002267 DOI: 10.1371/journal.pone.0015345] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 11/10/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND β2GPI is a major antigen for autoantibodies associated with antiphospholipid syndrome (APS), an autoimmune disease characterized by thrombosis and recurrent pregnancy loss. Only the dimeric form of β2GPI generated by anti-β2GPI antibodies is pathologically important, in contrast to monomeric β2GPI which is abundant in plasma. PRINCIPAL FINDINGS We created a dimeric inhibitor, A1-A1, to selectively target β2GPI in β2GPI/antibody complexes. To make this inhibitor, we isolated the first ligand-binding module from ApoER2 (A1) and connected two A1 modules with a flexible linker. A1-A1 interferes with two pathologically important interactions in APS, the binding of β2GPI/antibody complexes with anionic phospholipids and ApoER2. We compared the efficiency of A1-A1 to monomeric A1 for inhibition of the binding of β2GPI/antibody complexes to anionic phospholipids. We tested the inhibition of β2GPI present in human serum, β2GPI purified from human plasma and the individual domain V of β2GPI. We demonstrated that when β2GPI/antibody complexes are formed, A1-A1 is much more effective than A1 in inhibition of the binding of β2GPI to cardiolipin, regardless of the source of β2GPI. Similarly, A1-A1 strongly inhibits the binding of dimerized domain V of β2GPI to cardiolipin compared to the monomeric A1 inhibitor. In the absence of anti-β2GPI antibodies, both A1-A1 and A1 only weakly inhibit the binding of pathologically inactive monomeric β2GPI to cardiolipin. CONCLUSIONS Our results suggest that the approach of using a dimeric inhibitor to block β2GPI in the pathological multivalent β2GPI/antibody complexes holds significant promise. The novel inhibitor A1-A1 may be a starting point in the development of an effective therapeutic for antiphospholipid syndrome.
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Affiliation(s)
- Alexey Kolyada
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chang-Jin Lee
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Alfredo De Biasio
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Natalia Beglova
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Müller C, Thaler M, Schlichtiger A, Schreiegg A, Balling G, Steigerwald U, Luppa PB. β2-glycoprotein I-derived peptides as antigenic structures for the detection of antiphospholipid antibodies. J Thromb Haemost 2010; 8:2073-5. [PMID: 20629942 DOI: 10.1111/j.1538-7836.2010.03987.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Pozzi N, Banzato A, Bettin S, Bison E, Pengo V, De Filippis V. Chemical synthesis and characterization of wild-type and biotinylated N-terminal domain 1-64 of beta2-glycoprotein I. Protein Sci 2010; 19:1065-78. [PMID: 20440842 PMCID: PMC2868248 DOI: 10.1002/pro.387] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 03/04/2010] [Indexed: 11/08/2022]
Abstract
The antiphospholipid syndrome (APS) is a severe autoimmune disease associated with recurrent thrombosis and fetal loss and characterized by the presence of circulating autoantibodies (aAbs) mainly recognizing the N-terminal domain (DmI) of beta2-glycoprotein I (beta2GpI). To possibly block anti-beta2GpI Abs activity, we synthesized the entire DmI comprising residues 1-64 of beta2GpI by chemical methods. Oxidative disulfide renaturation of DmI was achieved in the presence of reduced and oxidized glutathione. The folded DmI (N-DmI) was purified by RP-HPLC, and its chemical identity and correct disulfide pairing (Cys4-Cys47 and Cys32-Cys60) were established by enzymatic peptide mass fingerprint analysis. The results of the conformational characterization, conducted by far- and near-UV CD and fluorescence spectroscopy, provided strong evidence for the native-like structure of DmI, which is also quite resistant to both Gdn-HCl and thermal denaturation. However, the thermodynamic stability of N-DmI at 37 degrees C was remarkably low, in agreement with the unfolding energetics of small proteins. Of note, aAbs failed to bind to plates coated with N-DmI in direct binding experiments. From ELISA competition experiments with plate-immobilized beta2GpI, a mean IC(50) value of 8.8 microM could be estimated for N-DmI, similar to that of the full-length protein, IC(50)(beta2GpI) = 6.4 microM, whereas the cysteine-reduced and carboxamidomethylated DmI, RC-DmI, failed to bind to anti-beta2GpI Abs. The versatility of chemical synthesis was also exploited to produce an N-terminally biotin-(PEG)(2)-derivative of N-DmI (Biotin-N-DmI) to be possibly used as a new tool in APS diagnosis. Strikingly, Biotin-N-DmI loaded onto a streptavidin-coated plate selectively recognized aAbs from APS patients.
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Affiliation(s)
- Nicola Pozzi
- Department of Pharmaceutical Sciences, University of Padova35131 Padova, Italy
| | - Alessandra Banzato
- Cardiology Unit, Department of Cardiologic, Thoracic and Vascular Sciences, University of PadovaPadova, Italy
| | - Samuele Bettin
- Department of Pharmaceutical Sciences, University of Padova35131 Padova, Italy
| | - Elisa Bison
- Cardiology Unit, Department of Cardiologic, Thoracic and Vascular Sciences, University of PadovaPadova, Italy
| | - Vittorio Pengo
- Cardiology Unit, Department of Cardiologic, Thoracic and Vascular Sciences, University of PadovaPadova, Italy
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Ioannou Y, Romay-Penabad Z, Pericleous C, Giles I, Papalardo E, Vargas G, Shilagard T, Latchman DS, Isenberg DA, Rahman A, Pierangeli S. In vivo inhibition of antiphospholipid antibody-induced pathogenicity utilizing the antigenic target peptide domain I of beta2-glycoprotein I: proof of concept. J Thromb Haemost 2009; 7:833-42. [PMID: 19220729 DOI: 10.1111/j.1538-7836.2009.03316.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
SUMMARY OBJECTIVES In the antiphospholipid syndrome (APS), the immunodominant epitope for the majority of circulating pathogenic antiphospholipid antibodies (aPLs) is the N-terminal domain I (DI) of beta(2)-glycoprotein I. We have previously shown that recombinant DI inhibits the binding of aPLs in fluid phase to immobilized native antigen, and that this inhibition is greater with the DI(D8S/D9G) mutant and absent with the DI(R39S) mutant. Hence, we hypothesized that DI and DI(D8S/D9G) would inhibit aPL-induced pathogenicity in vivo. METHODS C57BL/6 mice (n = 5, each group) were injected with purified IgG derived from APS patients (IgG-APS, 500 microg) or IgG from normal healthy serum (IgG-NHS) and either recombinant DI, DI(R39S), DI(D8S/D9G), or an irrelevant control peptide (at 10-40 microg). Outcome variables measured were femoral vein thrombus dynamics in treated and control groups following standardized vessel injury, expression of vascular cell adhesion molecule-1 (VCAM-1) on the aortic endothelial surface, and tissue factor (TF) activity in murine macrophages. RESULTS IgG-APS significantly increased thrombus size as compared with IgG-NHS. The IgG-APS thrombus enhancement effect was abolished in mice pretreated with recombinant DI (P CONCLUSION Our findings in this proof-of-concept study support the development of recombinant DI or the novel variant DI(D8S/D9G) as a potential future therapeutic agent for APS.
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Affiliation(s)
- Y Ioannou
- Centre for Rheumatology Research, Windeyer Building, University College London, London, UK.
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Urbanus RT, Pennings MTT, Derksen RHWM, de Groot PG. Platelet activation by dimeric beta2-glycoprotein I requires signaling via both glycoprotein Ibalpha and apolipoprotein E receptor 2'. J Thromb Haemost 2008; 6:1405-12. [PMID: 18485085 DOI: 10.1111/j.1538-7836.2008.03021.x] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Dimerization of beta(2)-glycoprotein I (beta(2)-GPI) by autoantibodies is thought to trigger the clinical manifestations observed in the antiphospholipid syndrome. Arterial thrombosis, a frequently occurring clinical manifestation of the antiphospholipid syndrome, is a process in which platelets play a crucial role. Previous work has shown that binding of dimeric beta(2)-GPI to the platelet receptors apolipoprotein E receptor 2' (ApoER2') and glycoprotein Ibalpha (GPIbalpha) mediates increased platelet activation in an in vitro thrombosis model. OBJECTIVE The individual roles of ApoER2' and GPIbalpha in mediating platelet activation by dimeric beta(2)-GPI has hitherto been unclear. In this study, we have determined the roles of either receptor in platelet activation by dimeric beta(2)-GPI. METHODS Platelet activation by dimeric beta(2)-GPI was studied under conditions of flow. Intracellular signaling induced by dimeric beta(2)-GPI was subsequently analyzed by means of sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) and western blot analysis. RESULTS The increase in platelet deposition onto a fibronectin surface under conditions of flow by dimeric beta(2)-GPI was completely abolished by inhibition of the interaction of dimeric beta(2)-GPI with either GPIbalpha or ApoER2'. Upon platelet stimulation with dimeric beta(2)-GPI, GPIbalpha translocated to the cytoskeleton via the scaffold protein 14-3-3zeta. Concomitantly, ApoER2' dissociated from the adapter protein Disabled1, presumably through phosphorylation of the cytoplasmic tail. Inhibition of one process could not inhibit the other. CONCLUSION We show that dimeric beta(2)-GPI signals via two distinct pathways in platelets, both of which are required for platelet activation. Abrogation of either signal results in loss of activation.
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Affiliation(s)
- R T Urbanus
- Department of Clinical Chemistry and Haematology, University Medical Centre Utrecht, Utrecht, The Netherlands
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Hamdan R, Maiti SN, Schroit AJ. Interaction of beta2-glycoprotein 1 with phosphatidylserine-containing membranes: ligand-dependent conformational alterations initiate bivalent binding. Biochemistry 2007; 46:10612-20. [PMID: 17715943 DOI: 10.1021/bi700621j] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Beta2-glycoprotein 1 (beta2GP1), a 50 kDa serum glycoprotein that binds anionic phospholipid-containing membranes, plays a regulatory role in physiology and pathology. The protein is a member of the short consensus repeat (SCR) superfamily containing four typical repeating domains and an aberrant fifth domain constructed into an SCR-like core at the C-terminus. To investigate the contribution of the individual domains to the binding of beta2GP1, a series of sequential domain-deleted recombinant protein fragments were generated and assessed for their interaction with PS-containing vesicles. Spectral analyses of lipid binding-dependent alterations in tryptophan emission spectra revealed that the (single) tryptophan residues of the individual domains underwent binding-dependent conformational alterations. Depending on the ionic strength, some domains moved from polar to nonpolar environments, while others moved from less polar to more polar environments. Analysis of a series of acrylamide quenching and resonance energy transfer experiments indicated that the binding of N-terminal domain 1 to PS membranes exists in two, ionic strength-dependent, conformations. At low ionic strengths, domain 1 bound to the vesicles and induced their precipitation and/or aggregation. At physiologic ionic strengths, domain 1 detached from the membrane surface while the remaining domains maintained their association with the membrane. Under these conditions, membrane-bound conformationally altered domain 1 projects away from the membrane surface, enabling it to interact with other proteins and/or cell surface ligands or receptors.
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Affiliation(s)
- Randala Hamdan
- Department of Cancer Biology, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4095, USA
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Pennings MTT, Derksen RHWM, Urbanus RT, Tekelenburg WL, Hemrika W, de Groot PG. Platelets express three different splice variants of ApoER2 that are all involved in signaling. J Thromb Haemost 2007; 5:1538-44. [PMID: 17470198 DOI: 10.1111/j.1538-7836.2007.02605.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND beta2-Glycoprotein I is the most relevant antigen in antiphospholipid syndrome. We have shown that binding of dimerized beta2-GPI to platelets via ApoER2' sensitizes platelets for second activating stimuli. OBJECTIVE Determine the region of ApoER2 involved in the binding of dimeric beta2-GPI. METHODS Cultured human megakaryocytes (MK) and three different human megakaryocytic cell lines were used for mRNA isolation to clone and express recombinant soluble platelet ApoER2. Domain deletion mutants of ApoER2 were constructed to identify the binding site for dimeric beta2-GPI. The presence of ApoER2 splice variants in platelets was demonstrated by immuno-blotting. RESULTS Three different mRNA splice variants were isolated from all four types of megakaryocytic cells used. Sequence analysis identified the splice variants: (i) shApoER2Delta5 lacking low-density lipoprotein (LDL) binding domains 4, 5 and 6; (ii) shApoER2Delta4-5 lacking LDL binding domains 3, 4, 5, 6 and (iii) shApoER2Delta3-4-5 lacking LDL binding domains 3, 4, 5, 6 and 7. The presence of three splice variants of ApoER2 on platelets was confirmed by immuno-blotting, with ApoER2Delta4-5 being the most abundantly expressed splice variant. Upon stimulation with dimeric beta2-GPI, all three splice variants were translocated to the cytosol; however, ApoER2Delta4-5 translocation was most prominent. Dimeric beta2-GPI binds platelet ApoER2 variants via LDL-binding domain 1. CONCLUSIONS Three different ApoER2 mRNA splice variants were isolated from MK and platelets express all three splice variants. All splice variants were shown to be functional by translocation upon stimulation with dimeric beta2-GPI. All three splice variants express LDL-binding domain 1.
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Affiliation(s)
- M T T Pennings
- Laboratory of Thrombosis and Haemostasis, Department of Clinical Chemistry and Hematology, UMCU Utrecht, Utrecht, The Netherlands
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Rahgozar S, Yang Q, Giannakopoulos B, Yan X, Miyakis S, Krilis SA. Beta2-glycoprotein I binds thrombin via exosite I and exosite II: anti-beta2-glycoprotein I antibodies potentiate the inhibitory effect of beta2-glycoprotein I on thrombin-mediated factor XIa generation. ACTA ACUST UNITED AC 2007; 56:605-13. [PMID: 17265495 DOI: 10.1002/art.22367] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
OBJECTIVE Beta(2)-glycoprotein I (beta(2)GPI) is a dominant antigenic target in antiphospholipid syndrome (APS). Beta(2)-glycoprotein I may bind to factor XI and serve a physiologic function as a regulator of factor XI activation by thrombin. We undertook this study to investigate the possible interactions of beta(2)GPI with thrombin in beta(2)GPI-regulated factor XI activation by thrombin and to evaluate the effect of anti-beta(2)GPI antibodies on this system. METHODS The beta(2)GPI interaction with thrombin was investigated in direct and competitive assays using beta(2)GPI domain mutants and thrombin-binding exosite oligonucleotides. Beta(2)-glycoprotein I inhibition of thrombin-mediated factor XI activation was assessed in the presence of 8 anti-beta(2)GPI monoclonal antibodies (mAb) directed against domain I. RESULTS Domain V of beta(2)GPI was involved in direct binding to thrombin, and exosite I and exosite II on thrombin took part in this interaction. Anti-beta(2)GPI mAb produced a >70% inhibition of thrombin-mediated factor XI activation in the presence of beta(2)GPI. CONCLUSION We demonstrate that beta(2)GPI interacts with thrombin exosites I and II. This novel finding necessitates a reinterpretation of previous studies from which the detection of anti-human thrombin antibodies in APS has been reported. We also show that anti-beta(2)GPI antibodies potentiate the inhibitory effect of beta(2)GPI on thrombin-mediated factor XIa generation.
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Affiliation(s)
- Soheila Rahgozar
- St George Hospital, University of New South Wales, Sydney, New South Wales, Australia
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Pennings MTT, van Lummel M, Derksen RHWM, Urbanus RT, Romijn RA, Lenting PJ, de Groot PG. Interaction of beta2-glycoprotein I with members of the low density lipoprotein receptor family. J Thromb Haemost 2006; 4:1680-90. [PMID: 16879209 DOI: 10.1111/j.1538-7836.2006.02036.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The antiphospholipid syndrome (APS) is a non-inflammatory autoimmune disease characterized by arterial and/or venous thrombosis and/or pregnancy morbidity in the presence of autoantibodies that recognize beta2-glycoprotein I (beta2GPI) bound to phospholipids. We have previously demonstrated that dimerization of beta2GPI by autoantibodies induces platelet activation, involving the platelet receptor apolipoprotein E receptor 2' (apoER2') a receptor belonging to the low-density lipoprotein receptor (LDL-R) family. Here, we show that dimeric beta2GPI, but not monomeric beta2GPI, interacts with four other LDL-R family members: the LDL-R related protein (LRP), megalin, the LDL-R and the very-low density lipoprotein receptor (VLDL-R). Interaction between dimeric beta2GPI and LDL-R, apoER2' and VLDL-R was best described with a one-site binding model (half-maximal binding; approximately 20 nm for apoER2' and VLDL-R and approximately 300 nm for LDL-R), whereas the interaction between dimeric beta2GPI and LRP or megalin was best described with a two-site binding model, representing a high- (approximately 3 nm) and a low-affinity site (approximately 0.2 microm). Binding to all receptors tested was unaffected by a tryptophane to serine (W316S) substitution in domain V of beta2GPI, which is known to disrupt the phospholipid binding site of beta2GPI. Also deletion of domain I or II left the interaction with the receptors unaffected. Deletion of domain V, however, significantly decreased the affinity for the receptors. In conclusion, our data show that dimeric beta2GPI can interact with different LDL-R family members. This interaction is dependent on a binding site within domain V of beta2GPI, which does not overlap with the phospholipid-binding site within domain V.
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Affiliation(s)
- M T T Pennings
- Department of Haematology, University Medical Center, Utrecht University, Utrecht, the Netherlands
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