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Won KD, Gil Gonzalez L, Cruz-Leal Y, Pavon Oro A, Lazarus AH. Antagonism of the Platelet-Activating Factor Pathway Mitigates Inflammatory Adverse Events Driven by Anti-erythrocyte Antibody Therapy in Mice. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2024; 212:1531-1539. [PMID: 38506555 DOI: 10.4049/jimmunol.2300638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 02/26/2024] [Indexed: 03/21/2024]
Abstract
Immune thrombocytopenia (ITP) is an autoimmune disease characterized by low platelet counts primarily due to antiplatelet autoantibodies. Anti-D is a donor-derived polyclonal Ab against the rhesus D Ag on erythrocytes used to treat ITP. Unfortunately, adverse inflammatory/hypersensitivity reactions and a Food and Drug Administration-issued black box warning have limited its clinical use. This underscores the imperative to understand the inflammatory pathway associated with anti-erythrocyte Ab-based therapies. TER119 is an erythrocyte-specific Ab with anti-D-like therapeutic activity in murine ITP, while also exhibiting a distinct inflammatory signature involving production of CCL2, CCL5, and CXCL9 but not IFN-γ. Therefore, TER119 has been used to elucidate the potential mechanism underlying the adverse inflammatory activity associated with anti-erythrocyte Ab therapy in murine ITP. Prior work has demonstrated that TER119 administration is associated with a dramatic decrease in body temperature and inflammatory cytokine/chemokine production. The work presented in the current study demonstrates that inhibiting the highly inflammatory platelet-activating factor (PAF) pathway with PAF receptor antagonists prevents TER119-driven changes in body temperature and inhibits the production of the CCL2, CCL5, and CXCL9 inflammatory cytokines in CD-1 mice. Phagocytic cells and a functional TER119 Fc region were found to be necessary for TER119-induced body temperature changes and increases in CXCL9 and CCL2. Taken together, this work reveals the novel requirement of the PAF pathway in causing adverse inflammatory activity associated with anti-erythrocyte Ab therapy in a murine model and provides a strategy of mitigating these potential reactions without altering therapeutic activity.
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Affiliation(s)
- Kevin Doyoon Won
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
- Department of Medicine and Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
| | - Lazaro Gil Gonzalez
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
| | - Yoelys Cruz-Leal
- Innovation and Portfolio Management, Canadian Blood Services, Ottawa, Ontario, Canada
| | - Alequis Pavon Oro
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
| | - Alan H Lazarus
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, Ontario, Canada
- Department of Medicine and Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada
- Innovation and Portfolio Management, Canadian Blood Services, Ottawa, Ontario, Canada
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Gil Gonzalez L, Won KD, Tawhidi Z, Cummins E, Cruz-Leal Y, Tundidor Cabado Y, Sachs UJ, Norris PAA, Shan Y, Bhakta V, Li J, Samudio I, Silva-Moreno B, Cerna-Portillo L, Pavon Oro A, Bergqvist P, Chan P, Moorehead A, Sholzberg M, Sheffield WP, Lazarus AH. Human Fc gamma receptor IIIA blockade inhibits platelet destruction in a humanized murine model of ITP. Blood Adv 2024; 8:1869-1879. [PMID: 38330193 PMCID: PMC11007428 DOI: 10.1182/bloodadvances.2023012155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 01/08/2024] [Accepted: 01/22/2024] [Indexed: 02/10/2024] Open
Abstract
ABSTRACT Fc gamma receptor (FcγR) IIIA is an important receptor for immunoglobulin G (IgG) and is involved in immune defense mechanisms as well as tissue destruction in some autoimmune diseases including immune thrombocytopenia (ITP). FcγRIIIA on macrophages can trigger phagocytosis of IgG-sensitized platelets, and prior pilot studies observed blockade of FcγRIIIA increased platelet counts in patients with ITP. Unfortunately, although blockade of FcγRIIIA in patients with ITP increased platelet counts, its engagement by the blocking antibody drove serious adverse inflammatory reactions. These adverse events were postulated to originate from the antibody's Fc and/or bivalent nature. The blockade of human FcγRIIIA in vivo with a monovalent construct lacking an active Fc region has not yet been achieved. To effectively block FcγRIIIA in vivo, we developed a high affinity monovalent single-chain variable fragment (scFv) that can bind and block human FcγRIIIA. This scFv (17C02) was expressed in 3 formats: a monovalent fusion protein with albumin, a 1-armed human IgG1 antibody, and a standard bivalent mouse (IgG2a) antibody. Both monovalent formats were effective in preventing phagocytosis of ITP serum-sensitized human platelets. In vivo studies using FcγR-humanized mice demonstrated that both monovalent therapeutics were also able to increase platelet counts. The monovalent albumin fusion protein did not have adverse event activity as assessed by changes in body temperature, whereas the 1-armed antibody induced some changes in body temperature even though the Fc region function was impaired by the Leu234Ala and Leu235Ala mutations. These data demonstrate that monovalent blockade of human FcγRIIIA in vivo can potentially be a therapeutic strategy for patients with ITP.
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Affiliation(s)
- Lazaro Gil Gonzalez
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Kevin D. Won
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - Zoya Tawhidi
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | | | - Yoelys Cruz-Leal
- Innovation and Portfolio Management, Canadian Blood Services, Ottawa, ON, Canada
| | - Yaima Tundidor Cabado
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Ulrich J. Sachs
- Institute for Clinical Immunology, Transfusion Medicine, and Haemostasis, Justus Liebig University, Giessen, Germany
- Department of Thrombosis and Haemostasis, Giessen University Hospital, Giessen, Germany
| | - Peter A. A. Norris
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Yuexin Shan
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Varsha Bhakta
- Innovation and Portfolio Management, Canadian Blood Services, Ottawa, ON, Canada
| | - Janessa Li
- adMare BioInnovations, Vancouver, BC, Canada
| | | | | | | | - Alequis Pavon Oro
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
| | | | | | - Amy Moorehead
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Michelle Sholzberg
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
| | - William P. Sheffield
- Innovation and Portfolio Management, Canadian Blood Services, Ottawa, ON, Canada
| | - Alan H. Lazarus
- Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Temerty Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Innovation and Portfolio Management, Canadian Blood Services, Ottawa, ON, Canada
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Cruz-Leal Y, Norris PAA, Gil Gonzalez L, Marjoram D, Wabnitz H, Shan Y, Lazarus AH. Trogocytosis drives red blood cell antigen loss in association with antibody-mediated immune suppression. Blood 2024; 143:807-821. [PMID: 37946269 DOI: 10.1182/blood.2023020860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 09/27/2023] [Accepted: 10/20/2023] [Indexed: 11/12/2023] Open
Abstract
ABSTRACT Red blood cell (RBC) alloimmunization to paternal antigens during pregnancy can cause hemolytic disease of the fetus and newborn (HDFN). This severe and potentially fatal neonatal disorder can be prevented by the administration of polyclonal anti-D through a mechanism referred to as antibody-mediated immune suppression (AMIS). Although anti-D prophylaxis effectively prevents HDFN, a lack of mechanistic clarity has hampered its replacement with recombinant agents. The major theories behind AMIS induction in the hematologic literature have classically centered around RBC clearance; however, antigen modulation/loss has recently been proposed as a potential mechanism of AMIS. To explore the primary mechanisms of AMIS, we studied the ability of 11 different antibodies to induce AMIS, RBC clearance, antigen loss, and RBC membrane loss in the HOD (hen egg lysozyme-ovalbumin-human Duffy) murine model. Antibodies targeting different portions of the HOD molecule could induce AMIS independent of their ability to clear RBCs; however, all antibodies capable of inducing a strong AMIS effect also caused significant in vivo loss of the HOD antigen in conjunction with RBC membrane loss. In vitro studies of AMIS-inducing antibodies demonstrated simultaneous RBC antigen and membrane loss, which was mediated by macrophages. Confocal live-cell microscopy revealed that AMIS-inducing antibodies triggered RBC membrane transfer to macrophages, consistent with trogocytosis. Furthermore, anti-D itself can induce trogocytosis even at low concentrations, when phagocytosis is minimal or absent. In view of these findings, we propose trogocytosis as a mechanism of AMIS induction.
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Affiliation(s)
- Yoelys Cruz-Leal
- Innovation and Portfolio Management, Canadian Blood Services, Ottawa, ON, Canada
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Peter A A Norris
- Innovation and Portfolio Management, Canadian Blood Services, Ottawa, ON, Canada
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Medicine Huddinge, Center for Hematology and Regenerative Medicine, Karolinska Institute, Stockholm, Sweden
| | - Lazaro Gil Gonzalez
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Danielle Marjoram
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Hanna Wabnitz
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
| | - Yuexin Shan
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Alan H Lazarus
- Innovation and Portfolio Management, Canadian Blood Services, Ottawa, ON, Canada
- Keenan Research Centre for Biomedical Science, St Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Medicine, University of Toronto, Toronto, ON, Canada
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Jiang X, Sun Y, Yang S, Wu Y, Wang L, Zou W, Jiang N, Chen J, Han Y, Huang C, Wu A, Zhang C, Wu J. Novel chemical-structure TPOR agonist, TMEA, promotes megakaryocytes differentiation and thrombopoiesis via mTOR and ERK signalings. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2023; 110:154637. [PMID: 36610353 DOI: 10.1016/j.phymed.2022.154637] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 12/12/2022] [Accepted: 12/28/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND Non-peptide thrombopoietin receptor (TPOR) agonists are promising therapies for the mitigation and treatment of thrombocytopenia. However, only few agents are available as safe and effective for stimulating platelet production for thrombocytopenic patients in the clinic. PURPOSE This study aimed to develop a novel small molecule TPOR agonist and investigate its underlying regulation of function in megakaryocytes (MKs) differentiation and thrombopoiesis. METHODS A potential active compound that promotes MKs differentiation and thrombopoiesis was obtained by machine learning (ML). Meanwhile, the effect was verified in zebrafish model, HEL and Meg-01 cells. Next, the key regulatory target was identified by Drug Affinity Responsive Target Stabilization Assay (DARTS), Cellular Thermal Shift Assay (CETSA), and molecular simulation experiments. After that, RNA-sequencing (RNA-seq) was used to further confirm the associated pathways and evaluate the gene expression induced during MK differentiation. In vivo, irradiation (IR) mice, C57BL/6N-TPORem1cyagen (Tpor-/-) mice were constructed by CRISPR/Cas9 technology to examine the therapeutic effect of TMEA on thrombocytopenia. RESULTS A natural chemical-structure small molecule TMEA was predicted to be a potential active compound based on ML. Obvious phenotypes of MKs differentiation were observed by TMEA induction in zebrafish model and TMEA could increase co-expression of CD41/CD42b, DNA content, and promote polyploidization and maturation of MKs in HEL and Meg-01 cells. Mechanically, TMEA could bind with TPOR protein and further regulate the PI3K/AKT/mTOR/P70S6K and MEK/ERK signal pathways. In vivo, TMEA evidently promoted platelet regeneration in mice with radiation-induced thrombocytopenia but had no effect on Tpor-/- and C57BL/6 (WT) mice. CONCLUSION TMEA could serve as a novel TPOR agonist to promote MKs differentiation and thrombopoiesis via mTOR and ERK signaling and could potentially be created as a promising new drug to treat thrombocytopenia.
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Affiliation(s)
- Xueqin Jiang
- State Key Laboratory of Biotherapy and Cancer Center, West China Medical School, Sichuan University, Chengdu, Sichuan 610041, China
| | - Yueshan Sun
- The Third People's Hospital of Chengdu, Chengdu, Sichuan 610031, China
| | - Shuo Yang
- Key Laboratory of Medical Electrophysiology of Ministry of Education of China, Medical Key Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Yuesong Wu
- Key Laboratory of Medical Electrophysiology of Ministry of Education of China, Medical Key Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Long Wang
- Key Laboratory of Medical Electrophysiology of Ministry of Education of China, Medical Key Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Wenjun Zou
- School of Pharmacy, Chengdu University of Traditional Chinese Medicine, Chengdu, Sichuan 611137, China
| | - Nan Jiang
- Key Laboratory of Medical Electrophysiology of Ministry of Education of China, Medical Key Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Jianping Chen
- School of Chinese Medicine, The University of Hong Kong, Hong Kong, China
| | - Yunwei Han
- The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Chunlan Huang
- The Affiliated Hospital of Southwest Medical University, Luzhou, Sichuan 646000, China
| | - Anguo Wu
- Key Laboratory of Medical Electrophysiology of Ministry of Education of China, Medical Key Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China.
| | - Chunxiang Zhang
- Key Laboratory of Medical Electrophysiology of Ministry of Education of China, Medical Key Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China.
| | - Jianming Wu
- Key Laboratory of Medical Electrophysiology of Ministry of Education of China, Medical Key Laboratory for Drug Discovery and Druggability Evaluation of Sichuan Province, School of Pharmacy, Southwest Medical University, Luzhou, Sichuan 646000, China; School of Basic Medical Sciences, Southwest Medical University, Luzhou, China.
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MacKeigan DT, Ni T, Shen C, Stratton TW, Ma W, Zhu G, Bhoria P, Ni H. Updated Understanding of Platelets in Thrombosis and Hemostasis: The Roles of Integrin PSI Domains and their Potential as Therapeutic Targets. Cardiovasc Hematol Disord Drug Targets 2021; 20:260-273. [PMID: 33001021 DOI: 10.2174/1871529x20666201001144541] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/20/2020] [Accepted: 07/26/2020] [Indexed: 11/22/2022]
Abstract
Platelets are small blood cells known primarily for their ability to adhere and aggregate at injured vessels to arrest bleeding. However, when triggered under pathological conditions, the same adaptive mechanism of platelet adhesion and aggregation may cause thrombosis, a primary cause of heart attack and stroke. Over recent decades, research has made considerable progress in uncovering the intricate and dynamic interactions that regulate these processes. Integrins are heterodimeric cell surface receptors expressed on all metazoan cells that facilitate cell adhesion, movement, and signaling, to drive biological and pathological processes such as thrombosis and hemostasis. Recently, our group discovered that the plexin-semaphorin-integrin (PSI) domains of the integrin β subunits exert endogenous thiol isomerase activity derived from their two highly conserved CXXC active site motifs. Given the importance of redox reactions in integrin activation and its location in the knee region, this PSI domain activity may be critically involved in facilitating the interconversions between integrin conformations. Our monoclonal antibodies against the β3 PSI domain inhibited its thiol isomerase activity and proportionally attenuated fibrinogen binding and platelet aggregation. Notably, these antibodies inhibited thrombosis without significantly impairing hemostasis or causing platelet clearance. In this review, we will update mechanisms of thrombosis and hemostasis, including platelet versatilities and immune-mediated thrombocytopenia, discuss critical contributions of the newly discovered PSI domain thiol isomerase activity, and its potential as a novel target for anti-thrombotic therapies and beyond.
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Affiliation(s)
- Daniel T MacKeigan
- Department of Physiology, University of Toronto, Toronto, ON M5S, Canada
| | - Tiffany Ni
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Chuanbin Shen
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Tyler W Stratton
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Wenjing Ma
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Guangheng Zhu
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Preeti Bhoria
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Canada
| | - Heyu Ni
- Department of Physiology, University of Toronto, Toronto, ON M5S, Canada
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Semple JW, Rebetz J, Maouia A, Kapur R. An update on the pathophysiology of immune thrombocytopenia. Curr Opin Hematol 2021; 27:423-429. [PMID: 32868673 DOI: 10.1097/moh.0000000000000612] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
: Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder mediated by antiplatelet autoantibodies and antigen-specific T cells that either destroy platelets peripherally in the spleen or impair platelet production in the bone marrow. There have been a plethora of publications relating to the pathophysiology of ITP and since January of 2019, at least 50 papers have been published on ITP pathophysiology. PURPOSE OF REVIEW To summarize the literature relating to the pathophysiology of ITP including the working mechanisms of therapies, T-cell and B-cell physiology, protein/RNA/DNA biochemistry, and animal models in an attempt to unify the perceived abnormal immune processes. RECENT FINDINGS The most recent pathophysiologic irregularities associated with ITP relate to abnormal T-cell responses, particularly, defective T regulatory cell activity and how therapeutics can restore these responses. The robust literature on T cells in ITP points to the notion that ITP is a disease initiated by faulty self-tolerance mechanisms very much like that of other organ-specific autoimmune diseases. There is also a large literature on new and existing animal models of ITP and these will be discussed. It appears that understanding how to specifically modulate T cells in patients with ITP will undoubtedly lead to effective antigen-specific therapeutics. CONCLUSIONS ITP is predominately a T cell disorder which leads to a breakdown in self tolerance mechanisms and allows for the generation of anti-platelet autoantibodies and T cells. Novel therapeutics that target T cells may be the most effective way to perhaps cure this disorder.
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Affiliation(s)
- John W Semple
- Division of Hematology and Transfusion Medicine, Lund University.,Clinical Immunology and Transfusion Medicine, Office of Medical Services, Region Skåne, Lund, Sweden
| | - Johan Rebetz
- Division of Hematology and Transfusion Medicine, Lund University
| | - Amal Maouia
- Division of Hematology and Transfusion Medicine, Lund University
| | - Rick Kapur
- Sanquin Research, Department of Experimental Immunohematology, Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
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Antihuman CD44 antibody BJ18 inhibits platelet phagocytosis by correcting aberrant FcɣR expression and M1 polarization in immune thrombocytopenia. Int Immunopharmacol 2021; 95:107502. [PMID: 33690000 DOI: 10.1016/j.intimp.2021.107502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 11/24/2022]
Abstract
BACKGROUND Immune thrombocytopenia (ITP) is an autoimmune hemorrhagic disease with a low platelet count. CD44 is a pivotal component involved in phagocytosis and inflammation, and monoclonal antibodies (mAbs) against CD44 have been shown to be beneficial in several autoimmune diseases. In the present study, we investigated the correlation between CD44 levels and disease severity in patients with ITP and explored the immunomodulatory mechanisms of the antihuman CD44 mAb BJ18 on platelet phagocytosis mediated by monocytes/macrophages. METHODS Plasma was collected from 45 participants to measure the circulating concentration of CD44 using ELISA. Peripheral blood mononuclear cells from patients and controls were isolated and induced to differentiate into monocytes/macrophages utilizing cytokines and drugs. CD44 expression on circulating cells and the effects of BJ18 on platelet phagocytosis, Fcɣ receptor (FcɣR) expression and M1/M2 polarization of macrophages were evaluated using flow cytometry and qPCR. RESULTS CD44 levels of both the soluble form found in plasma and the form expressed on the surface of circulating monocytes/macrophages were significantly elevated in ITP patients. Linear correlations were verified between the CD44 levels and major clinical characteristics. In an in vitro study, BJ18 successfully inhibited platelet phagocytosis by monocytes/macrophages obtained from ITP patients. Further studies indicated that BJ18 corrected abnormal FcγR expression on monocytes/macrophages. Moreover, the polarization of proinflammatory M1 macrophages could also be regulated by BJ18. CONCLUSIONS Our data indicated that the CD44 level has potential predictive value for disease severity and that the antihuman CD44 mAb BJ18 may be a promising therapy for ITP patients.
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