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Fei X, Li JF, Fang YD, Liu LP, Liu KJ, Zeng WW, Wang WH. Distribution characteristics of FcμR positive cells in small intestinal lymph nodes of Bactrian camel. PLoS One 2023; 18:e0287329. [PMID: 37471384 PMCID: PMC10358951 DOI: 10.1371/journal.pone.0287329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 06/02/2023] [Indexed: 07/22/2023] Open
Abstract
Exploring the expression characteristics of FcμR in small intestinal lymph nodes of bactrian camels can lay the foundation for further revealing the function of FcμR. The FcμR expression characteristics were systematically analysed by using prokaryotic expression, antibody preparation, immunohistochemical staining and statistical analysis. FcμR positive cells were mainly located in the lymphoid follicles and their numbers decreased in the order of duodenal lymph nodes, jejunal lymph nodes and ileal lymph nodes, and the number of positive cells was statistically significant between different intestinal segments (P<0.05). The FcμR is expressed in lymphoid follicular B cells, which not only facilitates the body's ability to regulate secretory IgM levels, but also acts as a local immune defence barrier. The small intestine has dual functions of immune tolerance and immune response, the proximal part mainly focuses on immune tolerance, and the distal part mainly focuses on immune response. This distribution ensures the unity of the duodenal absorption and immune defence, and also significantly increases the efficiency of the entire small intestine, which is why the number of FcμR positive cells decreases in the order of duodenal lymph nodes, jejunal lymph nodes and ileal lymph nodes.
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Affiliation(s)
- Xie Fei
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Jian fei Li
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Ying dong Fang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Li ping Liu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Ke Jiang Liu
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Wei wei Zeng
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
| | - Wen hui Wang
- College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, China
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2
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Kubagawa H, Clark C, Skopnik CM, Mahmoudi Aliabadi P, Al-Qaisi K, Teuber R, Jani PK, Radbruch A, Melchers F, Engels N, Wienands J. Physiological and Pathophysiological Roles of IgM Fc Receptor (FcµR) Isoforms. Int J Mol Sci 2023; 24:ijms24065728. [PMID: 36982860 PMCID: PMC10058298 DOI: 10.3390/ijms24065728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 03/14/2023] [Accepted: 03/14/2023] [Indexed: 03/30/2023] Open
Abstract
IgM is the first antibody to emerge during phylogeny, ontogeny, and immune responses and serves as a first line of defense. Effector proteins interacting with the Fc portion of IgM, such as complement and its receptors, have been extensively studied for their functions. IgM Fc receptor (FcµR), identified in 2009, is the newest member of the FcR family and is intriguingly expressed by lymphocytes only, suggesting the existence of distinct functions as compared to the FcRs for switched Ig isotypes, which are expressed by various immune and non-hematopoietic cells as central mediators of antibody-triggered responses by coupling the adaptive and innate immune responses. Results from FcµR-deficient mice suggest a regulatory function of FcµR in B cell tolerance, as evidenced by their propensity to produce autoantibodies of both IgM and IgG isotypes. In this article, we discuss conflicting views about the cellular distribution and potential functions of FcµR. The signaling function of the Ig-tail tyrosine-like motif in the FcµR cytoplasmic domain is now formally shown by substitutional experiments with the IgG2 B cell receptor. The potential adaptor protein associating with FcµR and the potential cleavage of its C-terminal cytoplasmic tail after IgM binding are still enigmatic. Critical amino acid residues in the Ig-like domain of FcµR for interacting with the IgM Cµ4 domain and the mode of interaction are now defined by crystallographic and cryo-electron microscopic analyses. Some discrepancies on these interactions are discussed. Finally, elevated levels of a soluble FcµR isoform in serum samples are described as the consequence of persistent B cell receptor stimulation, as seen in chronic lymphocytic leukemia and probably in antibody-mediated autoimmune disorders.
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Affiliation(s)
| | - Caren Clark
- Institute of Cellular & Molecular Immunology, University Medical Center, 37073 Göttingen, Germany
| | | | | | | | - Ruth Teuber
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany
| | - Peter K Jani
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany
| | | | - Fritz Melchers
- Deutsches Rheuma-Forschungszentrum, 10117 Berlin, Germany
| | - Niklas Engels
- Institute of Cellular & Molecular Immunology, University Medical Center, 37073 Göttingen, Germany
| | - Jürgen Wienands
- Institute of Cellular & Molecular Immunology, University Medical Center, 37073 Göttingen, Germany
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3
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Sun S, Qiao B, Han Y, Wang B, Wei S, Chen Y. Posttranslational modifications of platelet adhesion receptors. Pharmacol Res 2022; 183:106413. [PMID: 36007773 DOI: 10.1016/j.phrs.2022.106413] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/11/2022] [Accepted: 08/19/2022] [Indexed: 10/15/2022]
Abstract
Platelets play a key role in normal hemostasis, whereas pathological platelet adhesion is involved in various cardiovascular events. The underlying cause in cardiovascular events involves plaque rupture leading to subsequent platelet adhesion, activation, release, and eventual thrombosis. Traditional antithrombotic drugs often target the signal transduction process of platelet adhesion receptors by influencing the synthesis of some key molecules, and their effects are limited. Posttranslational modifications (PTMs) of platelet adhesion receptors increase the functional diversity of the receptors and affect platelet physiological and pathological processes. Antithrombotic drugs targeting PTMs of platelet adhesion receptors may represent a new therapeutic idea. In this review, various PTMs, including phosphorylation, glycosylation, ubiquitination, nitrosylation, methylation, lipidation, and proteolysis, of three platelet adhesion receptors, glycoprotein Ib-IX-V (GPIb-IX-V), glycoprotein VI (GPVI), and integrin αIIbβ3, are reviewed. It is important to comprehensively understand the PTMs process of platelet adhesion receptors.
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Affiliation(s)
- Shukun Sun
- Department of Emergency and Chest Pain Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Clinical Research Center for Emergency and Critical Care Medicine of Shandong Province, Institute of Emergency and Critical Care Medicine of Shandong University, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Bao Qiao
- Department of Emergency and Chest Pain Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Clinical Research Center for Emergency and Critical Care Medicine of Shandong Province, Institute of Emergency and Critical Care Medicine of Shandong University, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Yu Han
- Department of Emergency and Chest Pain Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Clinical Research Center for Emergency and Critical Care Medicine of Shandong Province, Institute of Emergency and Critical Care Medicine of Shandong University, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Bailu Wang
- Clinical Trial Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Shujian Wei
- Department of Emergency and Chest Pain Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Clinical Research Center for Emergency and Critical Care Medicine of Shandong Province, Institute of Emergency and Critical Care Medicine of Shandong University, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China.
| | - Yuguo Chen
- Department of Emergency and Chest Pain Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Clinical Research Center for Emergency and Critical Care Medicine of Shandong Province, Institute of Emergency and Critical Care Medicine of Shandong University, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China.
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4
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Upregulation of cAMP prevents antibody-mediated thrombus formation in COVID-19. Blood Adv 2021; 6:248-258. [PMID: 34753174 PMCID: PMC8580563 DOI: 10.1182/bloodadvances.2021005210] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 10/21/2021] [Indexed: 11/20/2022] Open
Abstract
Thromboembolic events are frequently reported in patients infected with the SARS-CoV-2 virus. The exact mechanisms of COVID-19 associated hypercoagulopathy, however, remain elusive. Recently, we observed that platelets (PLTs) from patients with severe COVID-19 infection express high levels of procoagulant markers, which were found to be associated with increased risk for thrombosis. In the current study, we investigated the time course as well as the mechanisms leading to procoagulant PLTs in COVID-19. Our study demonstrates the presence of PLT-reactive IgG antibodies that induce marked changes in PLTs in terms of increased inner-mitochondrial-transmembrane potential (Δψ) depolarization, phosphatidylserine (PS) externalization and P-selectin expression. The IgG-induced procoagulant PLTs and increased thrombus formation was mediated by ligation of PLT Fc gamma RIIA (FcγRIIA). In addition, PLTs´ contents of calcium and cyclic-adenosine-monophosphate (cAMP) were identified to play central role in antibody-induced procoagulant PLT formation. Most importantly, antibody-induced procoagulant events as well as increased thrombus formation in severe COVID-19 were inhibited by Iloprost a clinically approved therapeutic agent that increases the intracellular cAMP levels in PLTs. Our data indicate that upregulation of cAMP could be a potential therapeutic target to prevent antibody-mediated coagulopathy in COVID-19 disease.
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5
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Patel P, Michael JV, Naik UP, McKenzie SE. Platelet FcγRIIA in immunity and thrombosis: Adaptive immunothrombosis. J Thromb Haemost 2021; 19:1149-1160. [PMID: 33587783 DOI: 10.1111/jth.15265] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 01/14/2021] [Accepted: 02/09/2021] [Indexed: 12/16/2022]
Abstract
Sepsis and autoimmune diseases remain major causes of morbidity and mortality. The last decade has seen a new appreciation of platelets in host defense, in both immunity and thrombosis. Platelets are first responders in the blood to microbes or non-microbial antigens. The role of platelets in physiologic immunity is counterbalanced by their role in pathology, for example, microvascular thrombosis. Platelets encounter microbes and antigens via both innate and adaptive immune processes; platelets also help to shape the subsequent adaptive response. FcγRIIA is a receptor for immune complexes opsonized by IgG or pentraxins, and expressed in humans by platelets, granulocytes, monocytes and macrophages. With consideration of the roles of IgG and Fc receptors, the host response to microbes and autoantigens can be called adaptive immunothrombosis. Here we review newer developments involving platelet FcγRIIA in humans and humanized mice in immunity and thrombosis, with special attention to heparin-induced thrombocytopenia, systemic lupus erythematosus, and bacterial sepsis. Human genetic diversity in platelet receptors and the utility of humanized mouse models are highlighted.
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Affiliation(s)
- Pravin Patel
- Department of Medicine, Cardeza Foundation for Hematological Research, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - James V Michael
- Department of Medicine, Cardeza Foundation for Hematological Research, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Ulhas P Naik
- Department of Medicine, Cardeza Foundation for Hematological Research, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Steven E McKenzie
- Department of Medicine, Cardeza Foundation for Hematological Research, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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6
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The molecular basis of immune-based platelet disorders. Clin Sci (Lond) 2021; 134:2807-2822. [PMID: 33140828 DOI: 10.1042/cs20191101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/12/2020] [Accepted: 10/23/2020] [Indexed: 12/17/2022]
Abstract
Platelets have a predominant role in haemostasis, the maintenance of blood volume and emerging roles as innate immune cells, in wound healing and in inflammatory responses. Platelets express receptors that are important for platelet adhesion, aggregation, participation in inflammatory responses, and for triggering degranulation and enhancing thrombin generation. They carry a cargo of granules bearing enzymes, adhesion molecules, growth factors and cytokines, and have the ability to generate reactive oxygen species. The platelet is at the frontline of a host of cellular responses to invading pathogens, injury, and infection. Perhaps because of this intrinsic responsibility of a platelet to rapidly respond to thrombotic, pathological and immunological factors as part of their infantry role; platelets are susceptible to targeted attack by the adaptive immune system. Such attacks are often transitory but result in aberrant platelet activation as well as significant loss of platelet numbers and platelet function, paradoxically leading to elevated risks of both thrombosis and bleeding. Here, we discuss the main molecular events underlying immune-based platelet disorders with specific focus on events occurring at the platelet surface leading to activation and clearance.
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7
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Léopold V, Pereverzeva L, Schuurman AR, Reijnders TDY, Saris A, de Brabander J, van Linge CCA, Douma RA, Chouchane O, Nieuwland R, Wiersinga WJ, van 't Veer C, van der Poll T. Platelets are Hyperactivated but Show Reduced Glycoprotein VI Reactivity in COVID-19 Patients. Thromb Haemost 2021; 121:1258-1262. [PMID: 33412595 DOI: 10.1055/a-1347-5555] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Valentine Léopold
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Department of Anesthesiology and Critical Care, Paris University, Lariboisière Hospital, Paris, France.,Inserm UMR-S 942, Cardiovascular Markers in Stress Conditions (MASCOT), University of Paris, Paris, France
| | - Liza Pereverzeva
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Alex R Schuurman
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Tom D Y Reijnders
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Anno Saris
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Justin de Brabander
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Christine C A van Linge
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Renée A Douma
- Department of Internal Medicine, Flevo Hospital, Almere, The Netherlands
| | - Osoul Chouchane
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Rienk Nieuwland
- Laboratory of Experimental Clinical Chemistry, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - W Joost Wiersinga
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Division of Infectious Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Cornelis van 't Veer
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Tom van der Poll
- Center of Experimental and Molecular Medicine, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.,Division of Infectious Diseases, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
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8
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Borst O, Gawaz M. Glycoprotein VI - novel target in antiplatelet medication. Pharmacol Ther 2021; 217:107630. [DOI: 10.1016/j.pharmthera.2020.107630] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 07/11/2020] [Indexed: 02/07/2023]
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9
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Melki I, Allaeys I, Tessandier N, Mailhot B, Cloutier N, Campbell RA, Rowley JW, Salem D, Zufferey A, Laroche A, Lévesque T, Patey N, Rauch J, Lood C, Droit A, McKenzie SE, Machlus KR, Rondina MT, Lacroix S, Fortin PR, Boilard E. FcγRIIA expression accelerates nephritis and increases platelet activation in systemic lupus erythematosus. Blood 2020; 136:2933-2945. [PMID: 33331924 PMCID: PMC7751357 DOI: 10.1182/blood.2020004974] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 07/11/2020] [Indexed: 02/06/2023] Open
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune inflammatory disease characterized by deposits of immune complexes (ICs) in organs and tissues. The expression of FcγRIIA by human platelets, which is their unique receptor for immunoglobulin G antibodies, positions them to ideally respond to circulating ICs. Whereas chronic platelet activation and thrombosis are well-recognized features of human SLE, the exact mechanisms underlying platelet activation in SLE remain unknown. Here, we evaluated the involvement of FcγRIIA in the course of SLE and platelet activation. In patients with SLE, levels of ICs are associated with platelet activation. Because FcγRIIA is absent in mice, and murine platelets do not respond to ICs in any existing mouse model of SLE, we introduced the FcγRIIA (FCGR2A) transgene into the NZB/NZWF1 mouse model of SLE. In mice, FcγRIIA expression by bone marrow cells severely aggravated lupus nephritis and accelerated death. Lupus onset initiated major changes to the platelet transcriptome, both in FcγRIIA-expressing and nonexpressing mice, but enrichment for type I interferon response gene changes was specifically observed in the FcγRIIA mice. Moreover, circulating platelets were degranulated and were found to interact with neutrophils in FcγRIIA-expressing lupus mice. FcγRIIA expression in lupus mice also led to thrombosis in lungs and kidneys. The model recapitulates hallmarks of human SLE and can be used to identify contributions of different cellular lineages in the manifestations of SLE. The study further reveals a role for FcγRIIA in nephritis and in platelet activation in SLE.
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Affiliation(s)
- Imene Melki
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- Centre de Recherche Arthrite, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
| | - Isabelle Allaeys
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- Centre de Recherche Arthrite, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
| | - Nicolas Tessandier
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- Centre de Recherche Arthrite, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
| | - Benoit Mailhot
- Département de Médecine Moléculaire, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
- Axe Neurosciences, Université Laval, Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
| | - Nathalie Cloutier
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- Centre de Recherche Arthrite, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
| | - Robert A Campbell
- Department of Internal Medicine and Pathology, University of Utah, Salt Lake City, UT
- University of Utah Molecular Medicine Program, Eccles Institute of Human Genetics, Salt Lake City, UT
| | - Jesse W Rowley
- Department of Internal Medicine and Pathology, University of Utah, Salt Lake City, UT
- University of Utah Molecular Medicine Program, Eccles Institute of Human Genetics, Salt Lake City, UT
| | - David Salem
- Division of Rheumatology, Department of Medicine, McGill University, Montreal, QC, Canada
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Anne Zufferey
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- Centre de Recherche Arthrite, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
| | - Audrée Laroche
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- Centre de Recherche Arthrite, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
| | - Tania Lévesque
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- Centre de Recherche Arthrite, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
| | - Natalie Patey
- Centre Hospitalier Universitaire de Sainte-Justine, Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montreal, Montreal, QC, Canada
| | - Joyce Rauch
- Division of Rheumatology, Department of Medicine, McGill University, Montreal, QC, Canada
- Research Institute of the McGill University Health Centre, Montreal, QC, Canada
| | - Christian Lood
- Division of Rheumatology, Department of Medicine, University of Washington, Seattle, WA
| | - Arnaud Droit
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- Département de Médecine Moléculaire, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
| | - Steven E McKenzie
- Cardeza Foundation for Hematological Research, Thomas Jefferson University, Philadelphia, PA
| | - Kellie R Machlus
- Division of Hematology, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; and
| | - Matthew T Rondina
- Axe Neurosciences, Université Laval, Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- University of Utah Molecular Medicine Program, Eccles Institute of Human Genetics, Salt Lake City, UT
- Department of Internal Medicine-Geriatric Research Education and Clinical Center (GRECC), George E. Wahlen Veterans Affairs Medical Center (VAMC), Salt Lake City, UT
| | - Steve Lacroix
- Centre de Recherche Arthrite, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
- Département de Médecine Moléculaire, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
| | - Paul R Fortin
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- Centre de Recherche Arthrite, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
| | - Eric Boilard
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Québec, QC, Canada
- Centre de Recherche Arthrite, Faculté de Médecine de l'Université Laval, Québec, QC, Canada
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10
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Shedding of soluble glycoprotein VI is neither affected by animal-derived antibeta-2-glycoprotein 1 antibodies nor IgG fractions from patients with systemic lupus erythematosus. Blood Coagul Fibrinolysis 2020; 31:258-263. [DOI: 10.1097/mbc.0000000000000909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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11
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Hosseini E, Mohtashami M, Ghasemzadeh M. Down-regulation of platelet adhesion receptors is a controlling mechanism of thrombosis, while also affecting post-transfusion efficacy of stored platelets. Thromb J 2019; 17:20. [PMID: 31660046 PMCID: PMC6806620 DOI: 10.1186/s12959-019-0209-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 09/10/2019] [Indexed: 12/14/2022] Open
Abstract
Physiologically, upon platelet activation, uncontrolled propagation of thrombosis is prevented by regulating mechanisms which affect the expression and function of either platelet adhesion receptors or integrins. Receptor ectodomain shedding is an elective mechanism which is mainly involved in down-regulation of adhesion receptors GPIbα and GPVI. Platelet integrin αIIbβ3 can also be modulated with a calpain-dependent proteolytic cleavage. In addition, activating signals may induce the internalization of expressed receptors to selectively down-regulate their intensity. Alternatively, further activation of platelets is associated with microvesiculation as a none-selective mechanism which leads to the loss of membrane- bearing receptors. In a non-physiological condition, the storage of therapeutic platelets has also shown to be associated with the unwilling activation of platelets which triggers receptors down-regulation via aforementioned different mechanisms. Notably, herein the changes are time-dependent and not controllable. While the expression and shedding of pro-inflammatory molecules can induce post-transfusion adverse effects, stored-dependent loss of adhesion receptors by ectodomain shedding or microvesiculation may attenuate post-transfusion adhesive functions of platelets causing their premature clearance from circulation. In its first part, the review presented here aims to describe the mechanisms involved in down-regulation of platelet adhesion receptors. It then highlights the crucial role of ectodomain shedding and microvesiculation in the propagation of "platelet storage lesion" which may affect the post-transfusion efficacy of platelet components.
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Affiliation(s)
- Ehteramolsadat Hosseini
- 1Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Iranian Blood Transfusion Organization Building, Hemmat Exp. Way, Next to the Milad Tower, PO Box: 14665-1157, Tehran, Iran
| | - Maryam Mohtashami
- 1Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Iranian Blood Transfusion Organization Building, Hemmat Exp. Way, Next to the Milad Tower, PO Box: 14665-1157, Tehran, Iran
| | - Mehran Ghasemzadeh
- 1Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Iranian Blood Transfusion Organization Building, Hemmat Exp. Way, Next to the Milad Tower, PO Box: 14665-1157, Tehran, Iran.,2Australian Center for Blood Diseases, Monash University, Melbourne, Victoria 3004 Australia
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12
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Qiao J, Dunne E, Wines B, Kenny D, McCarthy GM, Hogarth PM, Xu K, Andrews RK, Gardiner EE. Plasma levels of the soluble form of the FcγRIIa receptor vary with receptor polymorphisms and are elevated in rheumatoid arthritis. Platelets 2019; 31:392-398. [DOI: 10.1080/09537104.2019.1647527] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Jianlin Qiao
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
- Blood Disease Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Eimear Dunne
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Bruce Wines
- Centre for Biomedical Research, Burnet Institute, Melbourne, Australia
| | - Dermot Kenny
- Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | | | - P. Mark Hogarth
- Centre for Biomedical Research, Burnet Institute, Melbourne, Australia
| | - Kailin Xu
- Blood Disease Institute, Xuzhou Medical University, Xuzhou, China
- Department of Hematology, the Affiliated Hospital of Xuzhou Medical University, Xuzhou, China
| | - Robert K. Andrews
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
| | - Elizabeth E. Gardiner
- ACRF Department of Cancer Biology and Therapeutics, John Curtin School of Medical Research, The Australian National University, Canberra, Australia
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13
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Nevzorova TA, Mordakhanova ER, Daminova AG, Ponomareva AA, Andrianova IA, Le Minh G, Rauova L, Litvinov RI, Weisel JW. Platelet factor 4-containing immune complexes induce platelet activation followed by calpain-dependent platelet death. Cell Death Discov 2019; 5:106. [PMID: 31263574 PMCID: PMC6591288 DOI: 10.1038/s41420-019-0188-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/29/2019] [Accepted: 06/05/2019] [Indexed: 01/23/2023] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a complication of heparin therapy sometimes associated with thrombosis. The hallmark of HIT is antibodies to the heparin/platelet factor 4 (PF4) complex that cause thrombocytopenia and thrombosis through platelet activation. Despite the clinical importance, the molecular mechanisms and late consequences of immune platelet activation are not fully understood. Here, we studied immediate and delayed effects of the complexes formed by human PF4 and HIT-like monoclonal mouse anti-human-PF4/heparin IgG antibodies (named KKO) on isolated human platelets in vitro. Direct platelet-activating effect of the KKO/PF4 complexes was corroborated by the overexpression of phosphatidylserine (PS) and P-selectin on the platelet surface. The immune platelet activation was accompanied by a decrease of the mitochondrial transmembrane potential (ΔΨm), concurrent with a significant gradual reduction of the ATP content in platelets, indicating disruption of energy metabolism. A combination of PS expression and mitochondrial depolarization induced by the PF4-containing immune complexes observed in a substantial fraction of platelets was considered as a sign of ongoing platelet death, as opposed to a subpopulation of activated live platelets with PS on the plasma membrane but normal ΔΨm. Both activated and dying platelets treated with KKO/PF4 formed procoagulant extracellular microvesicles bearing PS on their surface. Scanning and transmission electron microscopy revealed dramatic morphological changes of KKO/PF4-treated platelets, including their fragmentation, another indicator of cell death. Most of the effects of KKO/PF4 were prevented by an anti-FcγRII monoclonal antibody IV.3. The adverse functional and structural changes in platelets induced by the KKO/PF4 complexes were associated with strong time-dependent activation of calpain, but only trace cleavage of caspase 3. The results indicate that the pathogenic PF4-containing HIT-like immune complexes induce direct prothrombotic platelet activation via FcγRIIA receptors followed by non-apoptotic calpain-dependent death of platelets, which can be an important mechanism of thrombocytopenia during HIT development.
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Affiliation(s)
- Tatiana A. Nevzorova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 18 Kremlyovskaya St., Kazan, Russian Federation 420008 Russia
| | - Elmira R. Mordakhanova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 18 Kremlyovskaya St., Kazan, Russian Federation 420008 Russia
| | - Amina G. Daminova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 18 Kremlyovskaya St., Kazan, Russian Federation 420008 Russia
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky str., Kazan, Russian Federation 420111 Russia
| | - Anastasia A. Ponomareva
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 18 Kremlyovskaya St., Kazan, Russian Federation 420008 Russia
- Kazan Institute of Biochemistry and Biophysics, FRC Kazan Scientific Center of RAS, 2/31 Lobachevsky str., Kazan, Russian Federation 420111 Russia
| | - Izabella A. Andrianova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 18 Kremlyovskaya St., Kazan, Russian Federation 420008 Russia
| | - Giang Le Minh
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 18 Kremlyovskaya St., Kazan, Russian Federation 420008 Russia
| | - Lubica Rauova
- Children’s Hospital of Philadelphia, 3401 Civic Center Blvd, Philadelphia, PA 19104 USA
- Department of Pediatrics, University of Pennsylvania Perelman School of Medicine, 3401 Civic Center Blvd, Philadelphia, PA 19104 USA
| | - Rustem I. Litvinov
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 18 Kremlyovskaya St., Kazan, Russian Federation 420008 Russia
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, 421 Curie Boulevard, Philadelphia, PA 19104 USA
| | - John W. Weisel
- Institute of Fundamental Medicine and Biology, Kazan Federal University, 18 Kremlyovskaya St., Kazan, Russian Federation 420008 Russia
- Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, 421 Curie Boulevard, Philadelphia, PA 19104 USA
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14
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Anania JC, Chenoweth AM, Wines BD, Hogarth PM. The Human FcγRII (CD32) Family of Leukocyte FcR in Health and Disease. Front Immunol 2019; 10:464. [PMID: 30941127 PMCID: PMC6433993 DOI: 10.3389/fimmu.2019.00464] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 02/21/2019] [Indexed: 12/15/2022] Open
Abstract
FcγRs have been the focus of extensive research due to their key role linking innate and humoral immunity and their implication in both inflammatory and infectious disease. Within the human FcγR family FcγRII (activatory FcγRIIa and FcγRIIc, and inhibitory FcγRIIb) are unique in their ability to signal independent of the common γ chain. Through improved understanding of the structure of these receptors and how this affects their function we may be able to better understand how to target FcγR specific immune activation or inhibition, which will facilitate in the development of therapeutic monoclonal antibodies in patients where FcγRII activity may be desirable for efficacy. This review is focused on roles of the human FcγRII family members and their link to immunoregulation in healthy individuals and infection, autoimmunity and cancer.
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Affiliation(s)
- Jessica C Anania
- Centre for Biomedical Research, Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Alicia M Chenoweth
- Centre for Biomedical Research, Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | - Bruce D Wines
- Centre for Biomedical Research, Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Pathology, The University of Melbourne, Melbourne, VIC, Australia
| | - P Mark Hogarth
- Centre for Biomedical Research, Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology and Pathology, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Pathology, The University of Melbourne, Melbourne, VIC, Australia
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15
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Soluble GPVI is elevated in injured patients: shedding is mediated by fibrin activation of GPVI. Blood Adv 2019; 2:240-251. [PMID: 29437639 DOI: 10.1182/bloodadvances.2017011171] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 12/13/2017] [Indexed: 12/18/2022] Open
Abstract
Soluble glycoprotein VI (sGPVI) is shed from the platelet surface and is a marker of platelet activation in thrombotic conditions. We assessed sGPVI levels together with patient and clinical parameters in acute and chronic inflammatory conditions, including patients with thermal injury and inflammatory bowel disease and patients admitted to the intensive care unit (ICU) for elective cardiac surgery, trauma, acute brain injury, or prolonged ventilation. Plasma sGPVI was measured by enzyme-linked immunosorbent assay and was elevated on day 14 after thermal injury, and was higher in patients who developed sepsis. sGPVI levels were associated with sepsis, and the value for predicting sepsis was increased in combination with platelet count and Abbreviated Burn Severity Index. sGPVI levels positively correlated with levels of D-dimer (a fibrin degradation product) in ICU patients and patients with thermal injury. sGPVI levels in ICU patients at admission were significantly associated with 28- and 90-day mortality independent of platelet count. sGPVI levels in patients with thermal injury were associated with 28-day mortality at days 1, 14, and 21 when adjusting for platelet count. In both cohorts, sGPVI associations with mortality were stronger than D-dimer levels. Mechanistically, release of GPVI was triggered by exposure of platelets to polymerized fibrin, but not by engagement of G protein-coupled receptors by thrombin, adenosine 5'-diphosphate, or thromboxane mimetics. Enhanced fibrin production in these patients may therefore contribute to the observed elevated sGPVI levels. sGPVI is an important platelet-specific marker for platelet activation that predicts sepsis progression and mortality in injured patients.
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16
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Mechanisms of receptor shedding in platelets. Blood 2018; 132:2535-2545. [DOI: 10.1182/blood-2018-03-742668] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 10/12/2018] [Indexed: 02/07/2023] Open
Abstract
Abstract
The ability to upregulate and downregulate surface-exposed proteins and receptors is a powerful process that allows a cell to instantly respond to its microenvironment. In particular, mobile cells in the bloodstream must rapidly react to conditions where infection or inflammation are detected, and become proadhesive, phagocytic, and/or procoagulant. Platelets are one such blood cell that must rapidly acquire and manage proadhesive and procoagulant properties in order to execute their primary function in hemostasis. The regulation of platelet membrane properties is achieved via several mechanisms, one of which involves the controlled metalloproteolytic release of adhesion receptors and other proteins from the platelet surface. Proteolysis effectively lowers receptor density and reduces the reactivity of platelets, and is a mechanism to control robust platelet activation. Recent research has also established clear links between levels of platelet receptors and platelet lifespan. In this review, we will discuss the current knowledge of metalloproteolytic receptor regulation in the vasculature with emphasis on the platelet receptor system to highlight how receptor density can influence both platelet function and platelet survival.
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17
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Gardiner EE. Proteolytic processing of platelet receptors. Res Pract Thromb Haemost 2018; 2:240-250. [PMID: 30046726 PMCID: PMC6055504 DOI: 10.1002/rth2.12096] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Accepted: 03/01/2018] [Indexed: 12/17/2022] Open
Abstract
Platelets have a major role in hemostasis and an emerging role in biological processes including inflammation and immunity. Many of these processes require platelet adhesion and localization at sites of tissue damage or infection and regulated platelet activation, mediated by platelet adheso-signalling receptors, glycoprotein (GP) Ib-IX-V and GPVI. Work from a number of laboratories has demonstrated that levels of these receptors are closely regulated by metalloproteinases of the A Disintegrin And Metalloproteinase (ADAM) family, primarily ADAM17 and ADAM10. It is becoming increasingly evident that platelets have important roles in innate immunity, inflammation, and in combating infection that extends beyond processes of hemostasis. This overview will examine the molecular events that regulate levels of platelet receptors and then assess ramifications for these events in settings where hemostasis, inflammation, and infection processes are triggered.
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Affiliation(s)
- Elizabeth E. Gardiner
- ACRF Department of Cancer Biology and TherapeuticsJohn Curtin School of Medical ResearchThe Australian National UniversityCanberraACTAustralia
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18
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19
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Montague SJ. Soluble fibrin going for six. J Thromb Haemost 2017; 15:2393-2395. [PMID: 28981184 DOI: 10.1111/jth.13862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Indexed: 12/01/2022]
Affiliation(s)
- S J Montague
- The ACRF Department of Cancer Biology and Therapeutics, John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
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20
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Arthur JF, Gardiner EE, Andrews RK, Al-Tamimi M. Focusing on plasma glycoprotein VI. Thromb Haemost 2017; 107:648-55. [DOI: 10.1160/th11-10-0745] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 12/10/2011] [Indexed: 12/18/2022]
Abstract
SummaryNew methods for analysing both platelet and plasma forms of the platelet-specific collagen receptor, glycoprotein VI (GPVI) in experimental models or human clinical samples, and the development of the first therapeutic compounds based on dimeric soluble GPVI-Fc or anti-GPVI antibody-based constructs, coincide with increased understanding of the potential pathophysiological role of GPVI ligand binding and shedding. Platelet GPVI not only mediates platelet activation at the site of vascular injury where collagen is exposed, but is also implicated in the pathogenesis of other diseases, such as atherosclerosis and coagulopathy, rheumatoid arthritis and tumour metastasis. Here, we describe some of the critical mechanisms for generating soluble GPVI from platelets, and future avenues for exploiting this unique platelet-specific receptor for diagnosis and/or disease prevention.
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21
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Soluble glycoprotein VI, a specific marker of platelet activation is increased in the plasma of subjects with seropositive rheumatoid arthritis. PLoS One 2017; 12:e0188027. [PMID: 29141000 PMCID: PMC5687752 DOI: 10.1371/journal.pone.0188027] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 10/29/2017] [Indexed: 11/29/2022] Open
Abstract
Objectives Anti-citrullinated protein antibodies (ACPA) have been shown to cause platelet activation in vitro, through the low-affinity immunoglobulin G (IgG) receptor (FcγRIIa) on platelets. Platelet activation via engagement of FcγRIIa results in proteolytic cleavage and shedding of platelet specific glycoprotein VI (GPVI) which can be detected in the plasma as soluble GPVI (sGPVI). We hypothesized that plasma levels of sGPVI would be increased among patients with seropositive RA as a consequence of antibody-induced platelet activation and GPVI shedding. Methods Samples from 84 patients with RA (65 seropositive and 19 seronegative) and 67 healthy controls were collected prospectively and analysed for sGPVI using a standardised ELISA. Results Patients with seropositive RA had significantly higher levels of sGPVI compared to seronegative RA and controls. Median (IQR) sGPVI levels were 4.2 ng/ml (3.2, 8.0) in seropositve RA, 2.2 ng/ml (1.5, 3.5) in seronegative RA and 2.2 ng/ml (1.6, 3.4) in controls (p<0.0001). sGPVI levels correlated with ACPA titres (r = 0.32, p = 0.0026) and with RF titres (r = 0.48, p<0.0001). Conclusion Plasma sGPVI, a specific marker of platelet activation is increased among patients with seropositive RA.
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22
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Conway R, Murphy CL, Madigan A, Kavanagh P, Geraghty L, Redmond N, Helbert L, Carey JJ, Dunne E, Kenny D, McCarthy GM. Increased platelet reactivity as measured by plasma glycoprotein VI in gout. Platelets 2017; 29:821-826. [PMID: 29090618 DOI: 10.1080/09537104.2017.1366974] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Patients with gout have an increased risk of cardiovascular events. The glycoprotein VI (GPVI) receptor is found exclusively on platelets and megakaryocytes, is proteolytically cleaved upon platelet activation, and detectable in plasma as soluble GPVI (sGPVI). Therefore, elevated sGPVI is a marker of platelet activation and a risk marker for cardiovascular events. The aim of this study was to assess platelet activation, as measured by plasma sGPVI level in gout. Blood samples were taken from patients with gout or osteoarthritis, and from healthy volunteers. Demographic and clinical data were collected for all participants. Blood samples were processed as double-spun platelet-poor plasma. Plasma sGPVI levels were measured using enzyme-linked immunosorbent assay. Mann-Whitney U test was used to compare groups. In total, 91 patients were included, 27 during gout flare, 41 with intercritical gout, 23 with osteoarthritis, and 53 healthy controls. Median (interquartile range) sGPVI levels were 6.51 ng/mL (4.52, 8.41) in gout flare, 3.58 ng/mL (2.11, 5.55) in intercritical gout, 2.73 ng/mL (2.17, 3.72) in osteoarthritis, and 2.19 ng/mL (1.72, 3.31) in healthy controls. Plasma sGPVI levels in both gout groups were significantly increased compared to healthy controls (p < 0.005 for each), in gout flare compared to osteoarthritis (p < 0.005), and in gout flare compared to intercritical gout (p = 0.001). There was no significant difference in sGPVI levels in gout patients with and without tophi or in those prescribed colchicine. We conclude that patients with gout exhibit platelet hyperactivity as demonstrated by elevated sGPVI levels. Platelet activation is exacerbated in gout, especially during gout flares.
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Affiliation(s)
- Richard Conway
- a Department of Rheumatology , Mater Misericordiae University Hospital, Dublin Academic Medical Centre , Dublin , Ireland.,b CARD Newman Research Fellow, University College Dublin , Dublin , Ireland
| | - Claire-Louise Murphy
- c Centre for Rheumatology Research , University College London Division of Medicine , London , United Kingdom
| | - Anne Madigan
- a Department of Rheumatology , Mater Misericordiae University Hospital, Dublin Academic Medical Centre , Dublin , Ireland
| | - Patricia Kavanagh
- a Department of Rheumatology , Mater Misericordiae University Hospital, Dublin Academic Medical Centre , Dublin , Ireland
| | - Liz Geraghty
- a Department of Rheumatology , Mater Misericordiae University Hospital, Dublin Academic Medical Centre , Dublin , Ireland
| | - Niamh Redmond
- d Clinical Research Centre, Mater Misericordiae University Hospital, Dublin Academic Medical Centre , Dublin , Ireland
| | - Laura Helbert
- a Department of Rheumatology , Mater Misericordiae University Hospital, Dublin Academic Medical Centre , Dublin , Ireland
| | - John J Carey
- e Department of Rheumatology , Galway University Hospitals , Galway , Ireland
| | - Eimear Dunne
- f Cardiovascular Biology and Clinical Research Centre, Royal College of Surgeons in Ireland , Dublin , Ireland
| | - Dermot Kenny
- f Cardiovascular Biology and Clinical Research Centre, Royal College of Surgeons in Ireland , Dublin , Ireland
| | - Geraldine M McCarthy
- a Department of Rheumatology , Mater Misericordiae University Hospital, Dublin Academic Medical Centre , Dublin , Ireland
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23
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Rabbolini DJ, Gardiner EE, Morel‐Kopp M, Dunkley S, Jahangiri A, Lee CS, Stevenson WS, Ward CM. Anti-glycoprotein VI mediated immune thrombocytopenia: An under-recognized and significant entity? Res Pract Thromb Haemost 2017; 1:291-295. [PMID: 30046699 PMCID: PMC6058269 DOI: 10.1002/rth2.12033] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 06/27/2017] [Indexed: 11/05/2022] Open
Abstract
Idiopathic immune thrombocytopenia (ITP) is an autoimmune disorder characterized by relapsing/ remitting thrombocytopenia. Bleeding complications are infrequent with platelet counts above 30×109/L, and this level is commonly used as a threshold for treatment. The question of another/ co-existent diagnosis or an alternate mechanism of platelet destruction arises when bleeding is experienced with platelet counts above this threshold. We report a case of anti-GPVI mediated ITP that was diagnosed following investigations performed to address this key clinical question. A patient with ITP experienced exaggerated bruising symptoms despite a platelet count of 91×109/L. Platelet functional testing showed an isolated platelet defect of collagen-induced aggregation. Next generation sequencing excluded a pathogenic variant of GP6, and anti-GPVI antibodies that curtailed GPVI function were confirmed by extended platelet phenotyping. We propose that anti-GPVI mediated ITP may be under-recognized, and that inclusion of GPVI in antibody detection assays may improve their diagnostic utility and in turn, facilitate a better understanding of ITP pathophysiology and aid individualized treatment approaches.
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Affiliation(s)
- David J. Rabbolini
- Department of Haematology and Transfusion MedicineRoyal North Shore HospitalSydneyNSWAustralia
- Northern Blood Research CentreKolling Institute of Medical ResearchUniversity of SydneySydneyNSWAustralia
| | - Elizabeth E. Gardiner
- ACRF Department of Cancer Biology and TherapeuticsJohn Curtin School of Medical ResearchAustralian National UniversityCanberraACTAustralia
| | - Marie‐Christine Morel‐Kopp
- Department of Haematology and Transfusion MedicineRoyal North Shore HospitalSydneyNSWAustralia
- Northern Blood Research CentreKolling Institute of Medical ResearchUniversity of SydneySydneyNSWAustralia
| | | | - Anila Jahangiri
- ACRF Department of Cancer Biology and TherapeuticsJohn Curtin School of Medical ResearchAustralian National UniversityCanberraACTAustralia
| | - Christine S‐M. Lee
- ACRF Department of Cancer Biology and TherapeuticsJohn Curtin School of Medical ResearchAustralian National UniversityCanberraACTAustralia
| | - William S. Stevenson
- Department of Haematology and Transfusion MedicineRoyal North Shore HospitalSydneyNSWAustralia
- Northern Blood Research CentreKolling Institute of Medical ResearchUniversity of SydneySydneyNSWAustralia
| | - Christopher M. Ward
- Department of Haematology and Transfusion MedicineRoyal North Shore HospitalSydneyNSWAustralia
- Northern Blood Research CentreKolling Institute of Medical ResearchUniversity of SydneySydneyNSWAustralia
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24
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Minet V, Dogné JM, Mullier F. Functional Assays in the Diagnosis of Heparin-Induced Thrombocytopenia: A Review. Molecules 2017; 22:molecules22040617. [PMID: 28398258 PMCID: PMC6153750 DOI: 10.3390/molecules22040617] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 04/05/2017] [Accepted: 04/08/2017] [Indexed: 01/09/2023] Open
Abstract
A rapid and accurate diagnosis in patients with suspected heparin-induced thrombocytopenia (HIT) is essential for patient management but remains challenging. Current HIT diagnosis ideally relies on a combination of clinical information, immunoassay and functional assay results. Platelet activation assays or functional assays detect HIT antibodies that are more clinically significant. Several functional assays have been developed and evaluated in the literature. They differ in the activation endpoint studied; the technique or technology used; the platelet donor selection; the platelet suspension (washed platelets, platelet rich plasma or whole blood); the patient sample (serum or plasma); and the heparin used (type and concentrations). Inconsistencies in controls performed and associated results interpretation are common. Thresholds and performances are determined differently among papers. Functional assays suffer from interlaboratory variability. This lack of standardization limits the evaluation and the accessibility of functional assays in laboratories. In the present article, we review all the current activation endpoints, techniques and methodologies of functional assays developed for HIT diagnosis.
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Affiliation(s)
- Valentine Minet
- Department of Pharmacy, Namur Thrombosis and Hemostasis Center (NTHC), Namur Research Institute for LIfe Sciences (NARILIS), University of Namur, Namur 5000, Belgium.
| | - Jean-Michel Dogné
- Department of Pharmacy, Namur Thrombosis and Hemostasis Center (NTHC), Namur Research Institute for LIfe Sciences (NARILIS), University of Namur, Namur 5000, Belgium.
| | - François Mullier
- CHU UCL Namur, Namur Thrombosis and Hemostasis Center (NTHC), Hematology Laboratory, Université catholique de Louvain, Yvoir 5530, Belgium.
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25
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Kubagawa H, Skopnik CM, Zimmermann J, Durek P, Chang HD, Yoo E, Bertoli LF, Honjo K, Radbruch A. Authentic IgM Fc Receptor (FcμR). Curr Top Microbiol Immunol 2017; 408:25-45. [PMID: 28702710 DOI: 10.1007/82_2017_23] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Since the bona fide Fc receptor for IgM antibody (FcµR) was identified eight years ago, much progress has been made in defining its biochemical nature, cellular distribution, and effector function. However, there are clearly conflicting results, especially about the cellular distribution and function of murine FcµR. In this short article, we will discuss recent findings from us and other investigators along with our interpretations and comments that may help to resolve the existing puzzles and should open new avenues of investigation.
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Affiliation(s)
- Hiromi Kubagawa
- Deutsches Rheuma-Forschungszentrum in Berlin, 10117, Berlin, Germany.
| | | | - Jakob Zimmermann
- Deutsches Rheuma-Forschungszentrum in Berlin, 10117, Berlin, Germany
| | - Pawel Durek
- Deutsches Rheuma-Forschungszentrum in Berlin, 10117, Berlin, Germany
| | - Hyun-Dong Chang
- Deutsches Rheuma-Forschungszentrum in Berlin, 10117, Berlin, Germany
| | - Esther Yoo
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, 90095, USA
| | | | - Kazuhito Honjo
- Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, 35209, USA
| | - Andreas Radbruch
- Deutsches Rheuma-Forschungszentrum in Berlin, 10117, Berlin, Germany
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26
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Abstract
Proteolytic shedding of the extracellular ectodomain of platelet receptors provides a key mechanism for irreversible loss of ligand-binding capacity, and for regulating platelet function in health and disease. Platelets derived from megakaryocytes are small anucleate cells in peripheral blood, with the ability to rapidly adhere, become activated, and secrete an array of procoagulant and proinflammatory factors at sites of vascular injury or disease, and to form a platelet aggregate (thrombus) which is not only critical in normal hemostasis and wound healing, but in atherothrombotic diseases including myocardial infarction and ischemic stroke. Basic mechanisms of receptor shedding on platelets have important distinctions from how receptors on other cell types might be shed, in that shedding is rapidly initiated (within seconds to minutes) and occurs under altered shear conditions encountered in flowing blood or experimentally ex vivo. This review will consider the key components of platelet receptor shedding, that is, the receptor with relevant cleavage site, the (metallo)proteinase or sheddase and how its activity is regulated, and the range of known regulatory factors that control platelet receptor shedding including receptor-associated molecules such as calmodulin, factors controlling sheddase surface expression and activity, and other elements such as shear stress, plasma membrane properties, cellular activation status or age. Understanding these basic mechanisms of platelet receptor shedding is significant in terms of utilizing receptor surface expression or soluble proteolytic fragments as platelet-specific biomarkers and/or ultimately therapeutic targeting of these mechanisms to control platelet reactivity and function.
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Affiliation(s)
- Robert K Andrews
- a Australian Centre for Blood Diseases , Monash University , Melbourne , Australia 3004.,b Department of Cancer Biology and Therapeutics, the John Curtin School of Medical Research , Australian National University , Canberra , Australia 2600
| | - Elizabeth E Gardiner
- a Australian Centre for Blood Diseases , Monash University , Melbourne , Australia 3004.,b Department of Cancer Biology and Therapeutics, the John Curtin School of Medical Research , Australian National University , Canberra , Australia 2600
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27
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Chatterjee M, Gawaz M. Clinical significance of receptor shedding-platelet GPVI as an emerging diagnostic and therapeutic tool. Platelets 2016; 28:362-371. [PMID: 27753514 DOI: 10.1080/09537104.2016.1227062] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Platelet membrane bedecked with a wide array of receptors offers a platform to regulate platelet responsiveness, thrombotic propensity, inflammatory disposition, and immune reactivity under diverse pathophysiological conditions. Ectopic proteolytic cleavage of such receptors irreversibly inactivates receptor-mediated intracellular signaling governing cellular functions, further releases soluble fragments into circulation which might modulate functions of target cells. Glycoprotein VI-(GPVI) is a membrane glycoprotein expressed in platelets and megakaryocytes. Platelet GPVI surface expression is enhanced following acute ischemic events like myocardial infarction and cerebral stroke, serves as an imminent diagnostic tool independent of markers of tissue necrosis, and is associated with poor prognosis. Platelets undergo GPVI shedding and thereby contribute to soluble plasma levels of sGPVI, with distinct diagnostic and prognostic attributes. This review summarizes the functional significance and mechanistic basis whereby GPVI surface availability is up- or downregulated on platelets and the impact of GPVI in diagnostic, prognostic, and therapeutic strategies in diseases where platelets play a regulatory role. Further, we also highlight how novel non-invasive platelet-based diagnostic and therapeutic strategies have evolved utilizing GPVI for lesion-directed antithrombotic therapy or to counteract atherosclerotic disposition to ameliorate care of patients particularly in the context of cardio-cerebro-vascular medicine.
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Affiliation(s)
- Madhumita Chatterjee
- a Innere Medizin III, Kardiologie und Kreislauferkrankungen , Eberhard Karls Universität , Tübingen , Germany
| | - Meinrad Gawaz
- a Innere Medizin III, Kardiologie und Kreislauferkrankungen , Eberhard Karls Universität , Tübingen , Germany
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Qiao J, Al-Tamimi M, Baker RI, Andrews RK, Gardiner EE. The platelet Fc receptor, FcγRIIa. Immunol Rev 2016; 268:241-52. [PMID: 26497525 DOI: 10.1111/imr.12370] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Human platelets express FcγRIIa, the low-affinity receptor for the constant fragment (Fc) of immunoglobulin (Ig) G that is also found on neutrophils, monocytes, and macrophages. Engagement of this receptor on platelets by immune complexes triggers intracellular signaling events that lead to platelet activation and aggregation. Importantly these events occur in vivo, particularly in response to pathological immune complexes, and engagement of this receptor on platelets has been causally linked to disease pathology. In this review, we will highlight some of the key features of this receptor in the context of the platelet surface, and examine the functions of platelet FcγRIIa in normal hemostasis and in response to injury and infection. This review will also highlight pathological consequences of engagement of this receptor in platelet-based autoimmune disorders. Finally, we present some new data investigating whether levels of the extracellular ligand-binding region of platelet glycoprotein VI which is rapidly shed upon engagement of platelet FcγRIIa by autoantibodies, can report on the presence of pathological anti-heparin/platelet factor 4 immune complexes and thus identify patients with pathological autoantibodies who are at the greatest risk of developing life-threatening thrombosis in the setting of heparin-induced thrombocytopenia.
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Affiliation(s)
- Jianlin Qiao
- The Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia
| | - Mohammad Al-Tamimi
- Department of Basic Medical Sciences, Hashemite University, Zarqa, Jordan
| | - Ross I Baker
- Western Australian Centre for Thrombosis and Haemostasis, Murdoch University, Perth, WA, Australia
| | - Robert K Andrews
- The Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia
| | - Elizabeth E Gardiner
- The Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia
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29
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Au AE, Josefsson EC. Regulation of platelet membrane protein shedding in health and disease. Platelets 2016; 28:342-353. [PMID: 27494300 DOI: 10.1080/09537104.2016.1203401] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Extracellular proteolysis of platelet plasma membrane proteins is an event that ensues platelet activation. Shedding of surface receptors such as glycoprotein (GP) Ibα, GPV and GPVI as well as externalized proteins P-selectin and CD40L releases soluble ectodomain fragments that are subsequently detectable in plasma. This results in the irreversible functional downregulation of platelet receptor-mediated adhesive interactions and the generation of biologically active fragments. In this review, we describe molecular insights into the regulation of platelet receptor and ligand shedding in health and disease. The scope of this review is specially focused on GPIbα, GPV, GPVI, P-selectin and CD40L where we: (1) describe the basic physiological regulation of expression and shedding of these proteins in hemostasis illustrate alterations in receptor expression during (2) apoptosis and (3) ex vivo storage relevant for blood banking purposes; (4) discuss considerations to be made when analyzing and interpreting shedding of platelet membrane proteins and finally; (5) collate clinical evidence that quantify these platelet proteins during disease.
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Affiliation(s)
- Amanda E Au
- a The Walter and Eliza Hall Institute of Medical Research, Cancer & Haematology Division , 1G Royal Parade, Melbourne , Australia.,b Department of Medical Biology , The University of Melbourne , Melbourne , Australia
| | - Emma C Josefsson
- a The Walter and Eliza Hall Institute of Medical Research, Cancer & Haematology Division , 1G Royal Parade, Melbourne , Australia.,b Department of Medical Biology , The University of Melbourne , Melbourne , Australia
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30
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Abstract
Whilst significant effort has been focused on development of tools and approaches to clinically modulate activation processes that consume platelets, the platelet receptors that initiate activation processes remain untargeted. The modulation of receptor levels is also linked to underlying platelet aging processes which influence normal platelet lifespan and also the functionality and survival of stored platelets that are used in transfusion. In this review, we will focus on platelet adhesion receptors initiating thrombus formation, and discuss how regulation of levels of these receptors impact platelet function and platelet survival.
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Affiliation(s)
- Robert K Andrews
- a Australian Centre for Blood Diseases , Monash University , Melbourne , Australia
| | - Elizabeth E Gardiner
- b Department of Cancer Biology and Therapeutics, John Curtin School of Medical Research , Australian National University , Canberra , Australia
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31
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Rollin J, Pouplard C, Gruel Y. Risk factors for heparin-induced thrombocytopenia: Focus on Fcγ receptors. Thromb Haemost 2016; 116:799-805. [PMID: 27358188 DOI: 10.1160/th16-02-0109] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 05/28/2016] [Indexed: 02/06/2023]
Abstract
Fcγ receptors have critical roles in the pathophysiology of heparin-induced thrombocytopenia (HIT), a severe immune-mediated complication of heparin treatment. Activation of platelets, monocytes and neutrophils by platelet-activating anti-PF4/heparin IgG antibodies results in thrombocytopenia, hypercoagulability and thrombosis in susceptible patients, effects that depend on FcγRIIA. In addition, FcγRIIIA receptors probably contribute to clearance of platelets sensitised by HIT immune complexes. FcγRI has also been reported to be involved in monocyte activation by HIT IgG antibodies and synthesis of tissue factor. This review focuses on the role of these FcγRs in HIT pathophysiology, including the potential influence of several gene variations associated with variable risk of HIT and related thrombosis. In particular, the 276P and 326Q alleles of CD148, a protein tyrosine phosphatase that regulates FcγRIIA signalling, are associated with a lower risk of HIT, and platelets from healthy donors expressing these alleles are hyporesponsive to anti-PF4/H antibodies. It was also recently demonstrated that the risk of thrombosis is higher in HIT patients expressing the R isoform of the FcγRIIA H131R polymorphism, with HIT antibodies shown to activate RR platelets more efficiently, mainly explained by an inhibitory effect of normal IgG2, which bound to the FcγRIIA 131H isoform more efficiently. Environmental risk factors probably interact with these gene polymorphisms affecting FcγRs, thereby increasing thrombosis risk in HIT.
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Affiliation(s)
| | | | - Yves Gruel
- Yves Gruel, Service d'Hématologie-Hémostase, Hôpital Trousseau, CHU de Tours, 37044 Tours Cedex, France, Tel.: +33 02 47 47 46 72, E-mail:
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32
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Affiliation(s)
- Markus Bender
- Department of Experimental Biomedicine, University of Würzburg, University Hospital and Rudolf Virchow Center, Würzburg, Germany
| | - David Stegner
- Department of Experimental Biomedicine, University of Würzburg, University Hospital and Rudolf Virchow Center, Würzburg, Germany
| | - Bernhard Nieswandt
- Department of Experimental Biomedicine, University of Würzburg, University Hospital and Rudolf Virchow Center, Würzburg, Germany
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33
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Arman M, Krauel K. Human platelet IgG Fc receptor FcγRIIA in immunity and thrombosis. J Thromb Haemost 2015; 13:893-908. [PMID: 25900780 DOI: 10.1111/jth.12905] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 03/10/2015] [Indexed: 01/23/2023]
Abstract
Beyond their prominent role in hemostasis and thrombosis, platelets are increasingly recognized as having immunologic functions. Supporting this, human platelets express FcγRIIA (CD32a), a low-affinity Fc receptor (FcR) for the constant region of IgG that recognizes immune complexes (ICs) and IgG-opsonized cells with high avidity. In leukocytes, FcγRIIA engagement initiates strong effector functions that are key for immune and inflammatory responses, including cytokine release, antibody-dependent cell-mediated killing of pathogens, and internalization of ICs. However, the physiologic relevance of platelet-expressed FcγRIIA has received little attention in previous reviews on FcRs. This article summarizes and discusses the available information on human platelet FcγRIIA. The importance of this receptor in heparin-induced thrombocytopenia, a prothrombotic adverse drug effect, is well documented. However, studies demonstrating platelet activation by IgG-opsonized bacteria point to the physiologic relevance of platelet FcγRIIA in immunity. In this context, platelet activation and secretion may facilitate both a direct antimicrobial function of platelets and crosstalk with other immune cells. Additionally, a role for platelet FcγRIIA in IgG-independent hemostasis and physiologic thrombosis, by means of amplifying integrin αII b β3 outside-in signaling, has also been proposed. Nonetheless, the thrombotic complications found in some infective and autoimmune diseases may result from unbalanced FcγRIIA-mediated platelet aggregation. Moreover, FcγRIIA is not expressed in mice, and thrombocytopenia and/or thrombotic events found after drug administration can only be recapitulated by the use of human FcγRIIA-transgenic mice. Altogether, the available data support a functional role for platelet FcγRIIA in health and disease, and emphasize the need for further investigation of this receptor.
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Affiliation(s)
- M Arman
- Centre for Cardiovascular Sciences, Institute of Biomedical Research, School of Clinical and Experimental Medicine, College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK
| | - K Krauel
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
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34
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Abstract
PURPOSE OF REVIEW To review the recent developments in understanding the pathophysiology of heparin-induced thrombocytopenia (HIT) and in applying this knowledge to the treatment of patients with suspected and proven HIT. RECENT FINDINGS HIT pathophysiology is dynamic and complex. HIT pathophysiology is initiated by four essential components--heparin (Hep), platelet factor 4 (PF4), IgG antibodies against the Hep-PF4 complex, and platelet FcγRIIa. HIT is propagated by activated platelets, monocytes, endothelial cells, and coagulation proteins. Insights into the unique HIT antibody response continue to emerge, but without consensus as to the relative roles of B cells, T cells, and antigen-presenting cells. Platelet activation via FcγRIIa, the sine qua non of HIT, has become much better appreciated. Therapy remains challenging for several reasons. Suspected HIT is more frequent than proven HIT, because of the widespread use of Hep and the inadequacies of current diagnostic tests and scoring systems. In proven HIT, approved treatments reduce but do not eliminate thrombosis, and have substantial bleeding risk. Rational novel therapeutic strategies, directed at the initiating steps in HIT pathophysiology and with potential combinations staged over time, are in various phases of development. SUMMARY Progress continues in understanding the breadth of molecular and cellular players in HIT. Translation to improved diagnosis and treatment is needed.
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35
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Berndt MC, Metharom P, Andrews RK. Primary haemostasis: newer insights. Haemophilia 2014; 20 Suppl 4:15-22. [PMID: 24762270 DOI: 10.1111/hae.12427] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2014] [Indexed: 12/18/2022]
Abstract
At the same time as biophysical and omics approaches are drilling deeper into the molecular details of platelets and other blood cells, as well as their receptors and mechanisms of regulation, there is also an increasing awareness of the functional overlap between human vascular systems. Together, these studies are redefining the intricate networks linking haemostasis and thrombosis with inflammation, infectious disease, cancer/metastasis and other vascular pathophysiology. The focus of this state-of-the-art review is some of the newer advances relevant to primary haemostasis. Of particular interest, platelet-specific primary adhesion-signalling receptors and associated activation pathways control platelet function in flowing blood and provide molecular links to other systems. Platelet glycoprotein (GP)Ibα of the GPIb-IX-V complex and GPVI not only initiate platelet aggregation and thrombus formation by primary interactions with von Willebrand factor and collagen, respectively, but are also involved in coagulation, leucocyte engagement, bacterial or viral interactions, and are relevant as potential risk markers in a range of human diseases. Understanding these systems in unprecedented detail promises significant advances in evaluation of individual risk, in new diagnostic or therapeutic possibilities and in monitoring the response to drugs or other treatment.
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Affiliation(s)
- M C Berndt
- Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia
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36
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Abstract
The C-type lectin-like receptor CLEC-2 mediates platelet activation through a hem-immunoreceptor tyrosine-based activation motif (hemITAM). CLEC-2 initiates a Src- and Syk-dependent signaling cascade that is closely related to that of the 2 platelet ITAM receptors: glycoprotein (GP)VI and FcγRIIa. Activation of either of the ITAM receptors induces shedding of GPVI and proteolysis of the ITAM domain in FcγRIIa. In the present study, we generated monoclonal antibodies against human CLEC-2 and used these to measure CLEC-2 expression on resting and stimulated platelets and on other hematopoietic cells. We show that CLEC-2 is restricted to platelets with an average copy number of ∼2000 per cell and that activation of CLEC-2 induces proteolytic cleavage of GPVI and FcγRIIa but not of itself. We further show that CLEC-2 and GPVI are expressed on CD41+ microparticles in megakaryocyte cultures and in platelet-rich plasma, which are predominantly derived from megakaryocytes in healthy donors, whereas microparticles derived from activated platelets only express CLEC-2. Patients with rheumatoid arthritis, an inflammatory disease associated with increased microparticle production, had raised plasma levels of microparticles that expressed CLEC-2 but not GPVI. Thus, CLEC-2, unlike platelet ITAM receptors, is not regulated by proteolysis and can be used to monitor platelet-derived microparticles.
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37
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Abstract
While platelet activation is essential to maintain blood vessel patency and minimize loss of blood upon injury, untimely or excessive activity can lead to unwanted platelet activation and aggregation. Resultant thrombosis has the potential to block blood vessels, causing myocardial infarction or stroke. To tackle this major cause of mortality, clinical therapies that target platelet responsiveness (antiplatelet therapy) can successfully reduce cardiovascular events, especially in people at higher risk; however, all current antiplatelet therapies carry an increased probability of bleeding. This review will evaluate new and emerging targets for antithrombotics, focusing particularly on platelet glycoprotein VI, as blockade or depletion of this platelet-specific receptor conveys benefits in experimental models of thrombosis and thromboinflammation without causing major bleeding complications.
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Affiliation(s)
- Robert K Andrews
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia
| | - Jane F Arthur
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia
| | - Elizabeth E Gardiner
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia
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38
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Gardiner EE, Andrews RK, Cuker A. DiagnoSTic assays for heparin-induced thrombocytopenia. Br J Haematol 2014; 166:631-3. [PMID: 24824208 DOI: 10.1111/bjh.12940] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Elizabeth E Gardiner
- Australian Centre for Blood Diseases, Monash University, Melbourne, Vic., Australia
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39
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Platelet receptor expression and shedding: glycoprotein Ib-IX-V and glycoprotein VI. Transfus Med Rev 2014; 28:56-60. [PMID: 24674813 DOI: 10.1016/j.tmrv.2014.03.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 03/04/2014] [Accepted: 03/04/2014] [Indexed: 01/13/2023]
Abstract
Quantity, quality, and lifespan are 3 important factors in the physiology, pathology, and transfusion of human blood platelets. The aim of this review is to discuss the proteolytic regulation of key platelet-specific receptors, glycoprotein(GP)Ib and GPVI, involved in the function of platelets in hemostasis and thrombosis, and nonimmune or immune thrombocytopenia. The scope of the review encompasses the basic science of platelet receptor shedding, practical aspects related to laboratory analysis of platelet receptor expression/shedding, and clinical implications of using the proteolytic fragments as platelet-specific biomarkers in vivo in terms of platelet function and clearance. These topics can be relevant to platelet transfusion regarding both changes in platelet receptor expression occurring ex vivo during platelet storage and/or clinical use of platelets for transfusion. In this regard, quantitative analysis of platelet receptor profiles on blood samples from individuals could ultimately enable stratification of bleeding risk, discrimination between causes of thrombocytopenia due to impaired production vs enhanced clearance, and monitoring of response to treatment prior to change in platelet count.
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40
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Kubagawa H, Kubagawa Y, Jones D, Nasti TH, Walter MR, Honjo K. The old but new IgM Fc receptor (FcμR). Curr Top Microbiol Immunol 2014; 382:3-28. [PMID: 25116093 DOI: 10.1007/978-3-319-07911-0_1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
IgM is the first Ig isotype to appear during phylogeny, ontogeny and the immune response. The importance of both pre-immune "natural" and antigen-induced "immune" IgM antibodies in immune responses to pathogens and self-antigens has been established by studies of mutant mice deficient in IgM secretion. Effector proteins interacting with the Fc portion of IgM, such as complement and complement receptors, have thus far been proposed, but fail to fully account for the IgM-mediated immune protection and regulation of immune responses. Particularly, the role of the Fc receptor for IgM (FcμR) in such effector functions has not been explored until recently. We have identified an authentic FcμR in humans using a functional cloning strategy and subsequently in mice by RT-PCR and describe here its salient features and the immunological consequences of FcμR deficiency in mice. Since the FcμR we cloned was identical to Toso or Fas inhibitory molecule 3 (FAIM3), there have been spirited debates regarding the real function of FcμR/Toso/FAIM3 and we will also comment on this topic.
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Affiliation(s)
- Hiromi Kubagawa
- Division of Laboratory Medicine, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, 35209, USA,
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41
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Gardiner EE, Andrews RK. Structure and function of platelet receptors initiating blood clotting. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 844:263-75. [PMID: 25480646 DOI: 10.1007/978-1-4939-2095-2_13] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
At the clinical level, recent studies reveal the link between coagulation and other pathophysiological processes, including platelet activation, inflammation, cancer, the immune response, and/or infectious diseases. These links are likely to underpin the coagulopathy associated with risk factors for venous thromboembolic (VTE) and deep vein thrombosis (DVT). At the molecular level, the interactions between platelet-specific receptors and coagulation factors could help explain coagulopathy associated with aberrant platelet function, as well as revealing new approaches targeting platelet receptors in diagnosis or treatment of VTE or DVT. Glycoprotein (GP)Ibα, the major ligand-binding subunit of the platelet GPIb-IX-V complex, that binds the adhesive ligand, von Willebrand factor (VWF), is co-associated with the platelet-specific collagen receptor, GPVI. The GPIb-IX-V/GPVI adheso-signaling complex not only initiates platelet activation and aggregation (thrombus formation) in response to vascular injury or disease but GPIbα also regulates coagulation through a specific interaction with thrombin and other coagulation factors. Here, we discuss the structure and function of key platelet receptors involved in thrombus formation and coagulation in health and disease, with a particular focus on platelet GPIbα.
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Affiliation(s)
- Elizabeth E Gardiner
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia
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42
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Gardiner EE, Andrews RK. Plasma sGPVI: Changing levels in human disease. Thromb Res 2013; 133:306-7. [PMID: 24411101 DOI: 10.1016/j.thromres.2013.12.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 12/18/2013] [Accepted: 12/19/2013] [Indexed: 01/20/2023]
Affiliation(s)
- Elizabeth E Gardiner
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research & Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, 3004.
| | - Robert K Andrews
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research & Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, 3004.
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43
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Nazi I, Arnold DM, Smith JW, Horsewood P, Moore JC, Warkentin TE, Crowther MA, Kelton JG. FcγRIIa proteolysis as a diagnostic biomarker for heparin-induced thrombocytopenia. J Thromb Haemost 2013; 11:1146-53. [PMID: 23551961 DOI: 10.1111/jth.12208] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Indexed: 11/28/2022]
Abstract
BACKGROUND A significant challenge in the management of heparin-induced thrombocytopenia (HIT) patients is making a timely and accurate diagnosis. The readily available enzyme immunoassays (EIAs) have low specificities. In contrast, platelet activation assays have higher specificities, but they are technically demanding and not widely available. In addition, ~ 10% of samples referred for HIT testing are initially classified as indeterminate by the serotonin release assay (SRA), which further delays accurate diagnosis. HIT is characterized by platelet activation, which leads to FcγRIIa proteolysis. This raises the possibility that identification of the proteolytic fragment of FcγRIIa could serve as a surrogate marker for HIT. OBJECTIVES To determine the specificity of platelet FcγRIIa proteolysis induced by sera from patients with HIT, and to correlate the results with those of the SRA. METHODS/PATIENTS Sera from HIT patients and control patients with other thrombocytopenic/prothrombotic disorders were tested for their ability to proteolyse FcγRIIa. The results were correlated with anti-platelet factor 4 (PF4)/heparin antibodies (EIA), and heparin-dependent platelet activation (SRA). RESULTS Only HIT patient samples (20/20) caused heparin-dependent FcγRIIa proteolysis, similar to what was shown by the SRA. None of the samples from the other patient groups or hospital controls caused FcγRIIa proteolysis. Among nine additional samples that tested indeterminate in the SRA, FcγRIIa proteolysis resolved five samples that had a positive anti-PF4/heparin EIA result; three had no FcγRIIa proteolysis, and two were shown to have heparin-dependent FcγRIIa proteolysis CONCLUSIONS This study suggests that heparin-dependent FcγRIIa proteolysis is at least as specific as the SRA for the diagnosis of HIT.
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Affiliation(s)
- I Nazi
- Department of Medicine, Michael G DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.
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44
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Berndt MC, Andrews RK. Platelet hem-Immunoreceptor Tyrosine–Based Activation Motif Receptors. Arterioscler Thromb Vasc Biol 2013; 33:884-5. [DOI: 10.1161/atvbaha.113.301400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Michael C. Berndt
- From the Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia (M.C.B.); and Systems Haematology Laboratory, Australian Centre for Blood Diseases, Department of Clinical Haematology, Monash University, Melbourne, Australia (R.K.A.)
| | - Robert K. Andrews
- From the Faculty of Health Sciences, Curtin University, Perth, Western Australia, Australia (M.C.B.); and Systems Haematology Laboratory, Australian Centre for Blood Diseases, Department of Clinical Haematology, Monash University, Melbourne, Australia (R.K.A.)
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45
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Bender M, May F, Lorenz V, Thielmann I, Hagedorn I, Finney BA, Vögtle T, Remer K, Braun A, Bösl M, Watson SP, Nieswandt B. Combined in vivo depletion of glycoprotein VI and C-type lectin-like receptor 2 severely compromises hemostasis and abrogates arterial thrombosis in mice. Arterioscler Thromb Vasc Biol 2013; 33:926-34. [PMID: 23448972 DOI: 10.1161/atvbaha.112.300672] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Platelet inhibition is a major strategy to prevent acute ischemic cardiovascular and cerebrovascular events, which may, however, be associated with an increased bleeding risk. The (hem)immunoreceptor tyrosine activation motif-bearing platelet receptors, glycoprotein VI (GPVI) and C-type lectin-like receptor 2 (CLEC-2), might be promising antithrombotic targets because they can be depleted from circulating platelets by antibody treatment, leading to sustained antithrombotic protection, but only moderately increased bleeding times in mice. APPROACH AND RESULTS We investigated whether both (hem)immunoreceptor tyrosine activation motif-bearing receptors can be targeted simultaneously and what the in vivo consequences of such a combined therapeutic GPVI/CLEC-2 deficiency are. We demonstrate that isolated targeting of either GPVI or CLEC-2 in vivo does not affect expression or function of the respective other receptor. Moreover, simultaneous treatment with both antibodies resulted in the sustained loss of both GPVI and CLEC-2, while leaving other activation pathways intact. However, GPVI/CLEC-2-depleted mice displayed a dramatic hemostatic defect and profound impairment of arterial thrombus formation. Furthermore, a strongly diminished hemostatic response could also be reproduced in mice genetically lacking GPVI and CLEC-2. CONCLUSIONS These results demonstrate that GPVI and CLEC-2 can be simultaneously downregulated in platelets in vivo and reveal an unexpected functional redundancy of the 2 receptors in hemostasis and thrombosis. These findings may have important implications of the potential use of anti-GPVI and anti-CLEC-2-based agents in the prevention of thrombotic diseases.
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Affiliation(s)
- Markus Bender
- University Hospital Würzburg and Rudolf Virchow Center, DFG Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
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46
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Arthur JF, Shen Y, Chen Y, Qiao J, Ni R, Lu Y, Andrews RK, Gardiner EE, Cheng J. Exacerbation of glycoprotein VI-dependent platelet responses in a rhesus monkey model of Type 1 diabetes. J Diabetes Res 2013; 2013:370212. [PMID: 23841102 PMCID: PMC3690249 DOI: 10.1155/2013/370212] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 05/07/2013] [Indexed: 11/17/2022] Open
Abstract
Thrombosis is a life-threatening complication of diabetes. Platelet reactivity is crucial to thrombus formation, particularly in arterial vessels and in thrombotic complications causing myocardial infarction or ischaemic stroke, but diabetic patients often respond poorly to current antiplatelet medication. In this study, we used a nonhuman primate model of Type 1 diabetes to measure early downstream signalling events following engagement of the major platelet collagen receptor, glycoprotein (GP)VI. Diabetic monkeys were given enough insulin to maintain their blood glucose levels either at ~8 mM (well-controlled diabetes) or ~15 mM (poorly controlled diabetes). Flow cytometric analysis was used to measure platelet reactive oxygen species (ROS) generation, calcium mobilisation, receptor surface expression, and immature platelet fraction. We observed exacerbated intracellular ROS and calcium flux associated with engagement of GPVI in monkeys with poorly controlled diabetes. GPVI surface levels did not differ between healthy monkeys or the two diabetic groups. Treatment of platelets with the specific Syk inhibitor BAY61-3606 inhibited GPVI-dependent ROS and, importantly, reduced ROS generation in the poorly controlled diabetes group to that observed in healthy monkeys. These data indicate that glycaemic control is important in reducing GPVI-dependent platelet hyperreactivity and point to a potential antithrombotic therapeutic benefit of Syk inhibition in hyperglycaemic diabetes.
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Affiliation(s)
- J. F. Arthur
- Australian Centre for Blood Diseases, Alfred Medical Research & Education Precinct (AMREP), Monash University, Melbourne, VIC 3004, Australia
- *J. F. Arthur: and
| | - Y. Shen
- Australian Centre for Blood Diseases, Alfred Medical Research & Education Precinct (AMREP), Monash University, Melbourne, VIC 3004, Australia
| | - Y. Chen
- Key Laboratory of Transplant Engineering and Immunology, West China Hospital, Ministry of Health, Sichuan University, Chengdu 610041, China
| | - J. Qiao
- Australian Centre for Blood Diseases, Alfred Medical Research & Education Precinct (AMREP), Monash University, Melbourne, VIC 3004, Australia
| | - R. Ni
- Key Laboratory of Transplant Engineering and Immunology, West China Hospital, Ministry of Health, Sichuan University, Chengdu 610041, China
| | - Y. Lu
- Key Laboratory of Transplant Engineering and Immunology, West China Hospital, Ministry of Health, Sichuan University, Chengdu 610041, China
- *Y. Lu:
| | - R. K. Andrews
- Australian Centre for Blood Diseases, Alfred Medical Research & Education Precinct (AMREP), Monash University, Melbourne, VIC 3004, Australia
| | - E. E. Gardiner
- Australian Centre for Blood Diseases, Alfred Medical Research & Education Precinct (AMREP), Monash University, Melbourne, VIC 3004, Australia
| | - J. Cheng
- Key Laboratory of Transplant Engineering and Immunology, West China Hospital, Ministry of Health, Sichuan University, Chengdu 610041, China
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Wurster T, Poetz O, Stellos K, Kremmer E, Melms A, Schuster A, Nagel E, Joos T, Gawaz M, Bigalke B. Plasma levels of soluble glycoprotein VI (sGPVI) are associated with ischemic stroke. Platelets 2012; 24:560-5. [DOI: 10.3109/09537104.2012.746455] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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48
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Hofmann S, Vögtle T, Bender M, Rose-John S, Nieswandt B. The SLAM family member CD84 is regulated by ADAM10 and calpain in platelets. J Thromb Haemost 2012; 10:2581-92. [PMID: 23025437 DOI: 10.1111/jth.12013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND AND OBJECTIVE Ectodomain shedding is a major mechanism to modulate platelet receptor signaling and to downregulate platelet reactivity. Proteins of the a disintegrin and metalloproteinase (ADAM) family are implicated in the shedding of various platelet receptors. The signaling lymphocyte activation molecule (SLAM) family receptor CD84 is highly expressed in platelets and immune cells, but its role in platelet physiology is not well explored. Because of its ability to form homodimers, CD84 has been suggested to mediate contact-dependent signaling and contribute to thrombus stability. However, nothing is known about the cellular regulation of CD84. METHODS We studied the regulation of CD84 in murine platelets by biochemical approaches and use of three different genetically modified mouse lines. Regulation of CD84 in human platelets was studied using inhibitors and biochemical approaches. RESULTS We show that CD84 is cleaved from the surface of human and murine platelets in response to different shedding inducing agents and platelet receptor agonists. CD84 downregulation occurs through ectodomain-shedding and intracellular cleavage. Studies in transgenic mice identified ADAM10 as the principal sheddase responsible for CD84 cleavage, whereas ADAM17 was dispensable. Western blot analyses revealed calpain-mediated intracellular cleavage of the CD84 C-terminus, occurring simultaneously with, but independently of, ectodomain shedding. Furthermore, analysis of plasma and serum samples from transgenic mice demonstrated that CD84 is constitutively shed from the platelet surface by ADAM10 in vivo. CONCLUSIONS These results reveal a dual regulation mechanism for platelet CD84 by simultaneous extra- and intracellular cleavage that may modulate platelet-platelet and platelet-immune cell interactions.
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Affiliation(s)
- S Hofmann
- Chair of Vascular Medicine, University of Würzburg, University Hospital and Rudolf Virchow Center for Experimental Biomedicine, Würzburg, Germany
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Arthur JF, Qiao J, Shen Y, Davis AK, Dunne E, Berndt MC, Gardiner EE, Andrews RK. ITAM receptor-mediated generation of reactive oxygen species in human platelets occurs via Syk-dependent and Syk-independent pathways. J Thromb Haemost 2012; 10:1133-41. [PMID: 22489915 DOI: 10.1111/j.1538-7836.2012.04734.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
BACKGROUND Ligation of the platelet-specific collagen receptor, GPVI/FcRγ, causes rapid, transient disulfide-dependent homodimerization, and the production of intracellular reactive oxygen species (ROS) generated by the NADPH oxidase, linked to GPVI via TRAF4. OBJECTIVES The aim of this study was to evaluate the role of early signaling events in ROS generation following engagement of either GPVI/FcRγ or a second immunoreceptor tyrosine-based activation motif (ITAM)-containing receptor on platelets, FcγRIIa. METHODS AND RESULTS Using an H(2) DCF-DA-based flow cytometric assay to measure intracellular ROS, we show that treatment of platelets with either the GPVI agonists, collagen-related peptide (CRP) or convulxin (Cvx), or the FcγRIIa agonist 14A2, increased intraplatelet ROS; other platelet agonists such as ADP and TRAP did not. Basal ROS in platelet-rich plasma from 14 healthy donors displayed little inter-individual variability. CRP, Cvx or 14A2 induced an initial burst of ROS within 2 min followed by additional ROS reaching a plateau after 15-20 min. The Syk inhibitor BAY61-3606, which blocks ITAM-dependent signaling, had no effect on the initial ROS burst, but completely inhibited the second phase. CONCLUSIONS Together, these results show for the first time that ROS generation downstream of GPVI or FcγRIIa consists of two distinct phases: an initial Syk-independent burst followed by additional Syk-dependent generation.
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Affiliation(s)
- J F Arthur
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria, Australia.
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50
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Pathologic shear triggers shedding of vascular receptors: a novel mechanism for down-regulation of platelet glycoprotein VI in stenosed coronary vessels. Blood 2012; 119:4311-20. [PMID: 22431567 DOI: 10.1182/blood-2011-10-386607] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Ligand-induced ectodomain shedding of glycoprotein VI (GPVI) is a metalloproteinase-dependent event. We examined whether shear force, in the absence of GPVI ligand, was sufficient to induce shedding of GPVI. Human-citrated platelet-rich plasma or washed platelets were subjected to increasing shear rates in a cone-plate viscometer, and levels of intact and cleaved GPVI were examined by Western blot and ELISA. Pathophysiologic shear rates (3000-10 000 seconds(-1)) induced platelet aggregation and metalloproteinase-dependent appearance of soluble GPVI ectodomain, and GPVI platelet remnant. Shedding of GPVI continued after transient exposure to shear. Blockade of α(IIb)β(3), GPIbα, or intracellular signaling inhibited shear-induced platelet aggregation but minimally affected shear-induced shedding of GPVI. Shear-induced GPVI shedding also occurred in platelet-rich plasma or washed platelets isolated from a von Willebrand disease type 3 patient with no detectable VWF, implying that shear-induced activation of platelet metalloproteinases can occur in the absence of GPVI and GPIbα ligands. Significantly elevated levels of sGPVI were observed in 10 patients with stable angina pectoris, with well-defined single vessel coronary artery disease and mean intracoronary shear estimates at 2935 seconds(-1) (peak shear, 19 224 seconds(-1)). Loss of GPVI in platelets exposed to shear has potential implications for the stability of a forming thrombus at arterial shear rates.
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