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Wilhelm G, Mertowska P, Mertowski S, Przysucha A, Strużyna J, Grywalska E, Torres K. The Crossroads of the Coagulation System and the Immune System: Interactions and Connections. Int J Mol Sci 2023; 24:12563. [PMID: 37628744 PMCID: PMC10454528 DOI: 10.3390/ijms241612563] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/31/2023] [Accepted: 08/05/2023] [Indexed: 08/27/2023] Open
Abstract
The coagulation and immune systems, two vital systems in the human body, share intimate connections that fundamentally determine patient health. These systems work together through several common regulatory pathways, including the Tissue Factor (TF) Pathway. Immune cells expressing TF and producing pro-inflammatory cytokines can influence coagulation, while coagulation factors and processes reciprocally impact immune responses by activating immune cells and controlling their functions. These shared pathways contribute to maintaining health and are also involved in various pathological conditions. Dysregulated coagulation, triggered by infection, inflammation, or tissue damage, can result in conditions such as disseminated intravascular coagulation (DIC). Concurrently, immune dysregulation may lead to coagulation disorders and thrombotic complications. This review elucidates these intricate interactions, emphasizing their roles in the pathogenesis of autoimmune diseases and cancer. Understanding the complex interplay between these systems is critical for disease management and the development of effective treatments. By exploring these common regulatory mechanisms, we can uncover innovative therapeutic strategies targeting these intricate disorders. Thus, this paper presents a comprehensive overview of the mutual interaction between the coagulation and immune systems, highlighting its significance in health maintenance and disease pathology.
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Affiliation(s)
- Grzegorz Wilhelm
- Department of Plastic and Reconstructive Surgery and Microsurgery, Medical University of Lublin, 20-059 Lublin, Poland; (G.W.); (K.T.)
| | - Paulina Mertowska
- Department of Experimental Immunology, Medical University of Lublin, 20-093 Lublin, Poland; (S.M.); (E.G.)
| | - Sebastian Mertowski
- Department of Experimental Immunology, Medical University of Lublin, 20-093 Lublin, Poland; (S.M.); (E.G.)
| | - Anna Przysucha
- Chair and Department of Didactics and Medical Simulation, Medical University of Lublin, 20-093 Lublin, Poland;
| | - Jerzy Strużyna
- East Center of Burns Treatment and Reconstructive Surgery, Medical University of Lublin, 20-059 Lublin, Poland;
| | - Ewelina Grywalska
- Department of Experimental Immunology, Medical University of Lublin, 20-093 Lublin, Poland; (S.M.); (E.G.)
| | - Kamil Torres
- Department of Plastic and Reconstructive Surgery and Microsurgery, Medical University of Lublin, 20-059 Lublin, Poland; (G.W.); (K.T.)
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2
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Sarkar A, Khandelwal S, Koma GT, Kim H, Gruel Y, Rollin J, Passam F, Wool GD, Arepally GM, Cines DB, Rauova L, Poncz M. Treatment of thrombocytopenia and thrombosis in HIT in mice using deglycosylated KKO: a novel therapeutic? Blood Adv 2023; 7:4112-4123. [PMID: 37196641 PMCID: PMC10388731 DOI: 10.1182/bloodadvances.2023009661] [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: 01/03/2023] [Revised: 05/09/2023] [Accepted: 05/10/2023] [Indexed: 05/19/2023] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is characterized by thrombocytopenia associated with a highly prothrombotic state due to the development of pathogenic antibodies that recognize human platelet factor 4 (hPF4) complexed with various polyanions. Although nonheparin anticoagulants are the mainstay of care in HIT, subsequent bleeding may develop, and the risk of developing new thromboembolic events remain. We previously described a mouse immunoglobulin G2bκ (IgG2bκ) antibody KKO that mimics the sentinel features of pathogenic HIT antibodies, including binding to the same neoepitope on hPF4-polyanion complexes. KKO, like HIT IgGs, activates platelets through FcγRIIA and induces complement activation. We then questioned whether Fc-modified KKO could be used as a novel therapeutic to prevent or treat HIT. Using the endoglycosidase EndoS, we created deglycosylated KKO (DGKKO). Although DGKKO retained binding to PF4-polyanion complexes, it inhibited FcγRIIA-dependent activation of PF4-treated platelets triggered by unmodified KKO, 5B9 (another HIT-like monoclonal antibody), and IgGs isolated from patients with HIT. DGKKO also decreased complement activation and deposition of C3c on platelets. Unlike the anticoagulant fondaparinux, injection of DGKKO into HIT mice lacking mouse PF4, but transgenic for hPF4 and FcγRIIA, prevented and reversed thrombocytopenia when injected before or after unmodified KKO, 5B9, or HIT IgG. DGKKO also reversed antibody-induced thrombus growth in HIT mice. In contrast, DGKKO was ineffective in preventing thrombosis induced by IgG from patients with the HIT-related anti-PF4 prothrombotic disorder, vaccine-induced immune thrombotic thrombocytopenia. Thus, DGKKO may represent a new class of therapeutics for targeted treatment of patients with HIT.
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Affiliation(s)
- Amrita Sarkar
- Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | | | - Gavin T. Koma
- Department of Bioengineering, Temple University, Philadelphia, PA
| | - Hyunjun Kim
- Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Yves Gruel
- Department of Hemostasis, University Hospital Center of Tours, and EA4245 T2i, University of Tours, Tours, France
| | - Jerome Rollin
- Department of Hemostasis, University Hospital Center of Tours, and EA4245 T2i, University of Tours, Tours, France
| | - Freda Passam
- Central Clinical School, Faculty Medicine Health, University of Sydney, Sydney, Australia
| | | | | | - Douglas B. Cines
- Department of Pathology and Clinical Laboratories, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Lubica Rauova
- Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA
- Department of Pediatrics, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Mortimer Poncz
- Department of Pediatrics, The Children’s Hospital of Philadelphia, Philadelphia, PA
- Department of Pediatrics, The Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
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3
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Liang Z, Zheng X, Wang Y, Chu K, Gao Y. Using system biology and bioinformatics to identify the influences of COVID-19 co-infection with influenza virus on COPD. Funct Integr Genomics 2023; 23:175. [PMID: 37221323 DOI: 10.1007/s10142-023-01091-3] [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: 04/10/2023] [Revised: 05/07/2023] [Accepted: 05/09/2023] [Indexed: 05/25/2023]
Abstract
Coronavirus disease 2019 (COVID-19) has speedily increased mortality globally. Although they are risk factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), less is known about the common molecular mechanisms behind COVID-19, influenza virus A (IAV), and chronic obstructive pulmonary disease (COPD). This research used bioinformatics and systems biology to find possible medications for treating COVID-19, IAV, and COPD via identifying differentially expressed genes (DEGs) from gene expression datasets (GSE171110, GSE76925, GSE106986, and GSE185576). A total of 78 DEGs were subjected to functional enrichment, pathway analysis, protein-protein interaction (PPI) network construct, hub gene extraction, and other potentially relevant disorders. Then, DEGs were discovered in networks including transcription factor (TF)-gene connections, protein-drug interactions, and DEG-microRNA (miRNA) coregulatory networks by using NetworkAnalyst. The top 12 hub genes were MPO, MMP9, CD8A, HP, ELANE, CD5, CR2, PLA2G7, PIK3R1, SLAMF1, PEX3, and TNFRSF17. We found that 44 TFs-genes, as well as 118 miRNAs, are directly linked to hub genes. Additionally, we searched the Drug Signatures Database (DSigDB) and identified 10 drugs that could potentially treat COVID-19, IAV, and COPD. Therefore, we evaluated the top 12 hub genes that could be promising DEGs for targeted therapy for SARS-CoV-2 and identified several prospective medications that may benefit COPD patients with COVID-19 and IAV co-infection.
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Affiliation(s)
- Zihao Liang
- Clinical Research Center, the Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Xudong Zheng
- Department of Immunology, School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Yuan Wang
- Clinical Research Center, the Second Hospital of Nanjing, Nanjing University of Chinese Medicine, Nanjing, 210023, China
| | - Kai Chu
- Department of Vaccine Clinical Evaluation, Jiangsu Provincial Center for Disease Control and Prevention, Nanjing, 210009, China.
| | - Yanan Gao
- Department of Immunology, School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing, 210023, China.
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4
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Mongirdienė A, Liuizė A, Kašauskas A. Novel Knowledge about Molecular Mechanisms of Heparin-Induced Thrombocytopenia Type II and Treatment Targets. Int J Mol Sci 2023; 24:ijms24098217. [PMID: 37175923 PMCID: PMC10179321 DOI: 10.3390/ijms24098217] [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: 02/28/2023] [Revised: 04/04/2023] [Accepted: 04/07/2023] [Indexed: 05/15/2023] Open
Abstract
Heparin-induced thrombocytopenia type II (HIT II), as stated in the literature, occurs in about 3% of all patients and in 0.1-5% of surgical patients. Thrombosis develops in 20-64% of patients with HIT. The mortality rate in HIT II has not decreased using non-heparin treatment with anticoagulants such as argatroban and lepirudin. An improved understanding of the pathophysiology of HIT may help identify targeted therapies to prevent thrombosis without subjecting patients to the risk of intense anticoagulation. The review will summarize the current knowledge about the pathogenesis of HIT II, potential new therapeutic targets related to it, and new treatments being developed. HIT II pathogenesis involves multi-step immune-mediated pathways dependent on the ratio of PF4/heparin and platelet, monocyte, neutrophil, and endothelium activation. For years, only platelets were known to take part in HIT II development. A few years ago, specific receptors and signal-induced pathways in monocytes, neutrophils and endothelium were revealed. It had been shown that the cells that had become active realised different newly formed compounds (platelet-released TF, TNFα, NAP2, CXCL-7, ENA-78, platelet-derived microparticles; monocytes-TF-MPs; neutrophils-NETs), leading to additional cell activation and consequently thrombin generation, resulting in thrombosis. Knowledge about FcγIIa receptors on platelets, monocytes, neutrophils and FcγIIIa on endothelium, chemokine (CXCR-2), and PSGL-1 receptors on neutrophils could allow for the development of a new non-anticoagulant treatment for HIT II. IgG degradation, Syk kinase and NETosis inhibition are in the field of developing new treatment possibilities too. Accordingly, IdeS and DNases-related pathways should be investigated for better understanding of HIT pathogenesis and the possibilities of being the HIT II treatment targets.
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Affiliation(s)
- Aušra Mongirdienė
- Department of Biochemistry, Medical Academy, Lithuanian University of Health Sciences, LT-50161 Kaunas, Lithuania
| | - Agnė Liuizė
- Medicine Academy, Lithuanian University of Health Sciences, Eiveniu Str. 4, LT-50103 Kaunas, Lithuania
| | - Artūras Kašauskas
- Department of Biochemistry, Medical Academy, Lithuanian University of Health Sciences, LT-50161 Kaunas, Lithuania
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Revelly E, Scala E, Rosner L, Rancati V, Gunga Z, Kirsch M, Ltaief Z, Rusca M, Bechtold X, Alberio L, Marcucci C. How to Solve the Conundrum of Heparin-Induced Thrombocytopenia during Cardiopulmonary Bypass. J Clin Med 2023; 12:jcm12030786. [PMID: 36769435 PMCID: PMC9918281 DOI: 10.3390/jcm12030786] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 01/13/2023] [Accepted: 01/16/2023] [Indexed: 01/20/2023] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a major issue in cardiac surgery requiring cardiopulmonary bypass (CPB). HIT represents a severe adverse drug reaction after heparin administration. It consists of immune-mediated thrombocytopenia paradoxically leading to thrombotic events. Detection of antibodies against platelets factor 4/heparin (anti-PF4/H) and aggregation of platelets in the presence of heparin in functional in vitro tests confirm the diagnosis. Patients suffering from HIT and requiring cardiac surgery are at high risk of lethal complications and present specific challenges. Four distinct phases are described in the usual HIT timeline, and the anticoagulation strategy chosen for CPB depends on the phase in which the patient is categorized. In this sense, we developed an institutional protocol covering each phase. It consisted of the use of a non-heparin anticoagulant such as bivalirudin, or the association of unfractionated heparin (UFH) with a potent antiplatelet drug such as tirofiban or cangrelor. Temporary reduction of anti-PF4 with intravenous immunoglobulins (IvIg) has recently been described as a complementary strategy. In this article, we briefly described the pathophysiology of HIT and focused on the various strategies that can be applied to safely manage CPB in these patients.
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Affiliation(s)
- Etienne Revelly
- Department of Anesthesiology, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
- Correspondence:
| | - Emmanuelle Scala
- Department of Anesthesiology, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
- Faculty of Biology and Medicine, University of Lausanne (UNIL), Rue du Bugnon 21, 1011 Lausanne, Switzerland
| | - Lorenzo Rosner
- Department of Anesthesiology, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
| | - Valentina Rancati
- Department of Anesthesiology, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
| | - Ziyad Gunga
- Department of Cardiac Surgery, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
| | - Matthias Kirsch
- Faculty of Biology and Medicine, University of Lausanne (UNIL), Rue du Bugnon 21, 1011 Lausanne, Switzerland
- Department of Cardiac Surgery, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
| | - Zied Ltaief
- Department of Intensive Care Medicine, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
| | - Marco Rusca
- Department of Intensive Care Medicine, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
| | - Xavier Bechtold
- Department of Cardiac Surgery, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
| | - Lorenzo Alberio
- Faculty of Biology and Medicine, University of Lausanne (UNIL), Rue du Bugnon 21, 1011 Lausanne, Switzerland
- Division of Hematology and Central Hematology Laboratory, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
| | - Carlo Marcucci
- Department of Anesthesiology, Lausanne University Hospital (CHUV), 1011 Lausanne, Switzerland
- Faculty of Biology and Medicine, University of Lausanne (UNIL), Rue du Bugnon 21, 1011 Lausanne, Switzerland
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Genome-wide association study of platelet factor 4/heparin antibodies in heparin-induced thrombocytopenia. Blood Adv 2022; 6:4137-4146. [PMID: 35533259 PMCID: PMC9327558 DOI: 10.1182/bloodadvances.2022007673] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 05/02/2022] [Indexed: 11/20/2022] Open
Abstract
Heparin, a widely used anticoagulant, carries the risk of an antibody mediated adverse drug reaction, heparin-induced thrombocytopenia (HIT). A subset of heparin-treated patients produces detectable levels of antibodies against complexes of heparin bound to circulating platelet factor 4 (PF4). Using a genome-wide association study (GWAS) approach, we aimed to identify genetic variants associated with anti-PF4/heparin antibodies that account for the variable antibody response seen in HIT. We performed a GWAS on anti-PF4/heparin antibody levels determined via polyclonal enzyme-linked immunosorbent assays (ELISA). Our discovery cohort (n=4237) and replication cohort (n=807) constituted patients with European ancestry and clinical suspicion of HIT with cases confirmed via functional assay. Genome-wide significance was considered at α=5x10-8. No variants were significantly associated with anti-PF4/heparin antibody levels in the discovery cohort at a genome-wide significant level. Secondary GWAS analyses included identification of variants with suggestive associations in the discovery cohort (α=1x10-4). The top variant in both cohorts was rs1555175145 (discovery β=-0.112[0.018], p=2.50x10-5; replication β=-0.104[0.051], p=0.041). In gene set enrichment analysis (GSEA), three gene sets reached false discovery rate-adjusted significance (q<0.05) in both discovery and replication cohorts: "Leukocyte Transendothelial Migration," "Innate Immune Response," and "Lyase Activity." Our results indicate that genomic variation is not significantly associated with anti-PF4/heparin antibody levels. Given our power to identify variants with moderate frequencies and effect sizes, this evidence suggests genetic variation is not a primary driver of variable antibody response in heparin-treated patients with European ancestry.
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7
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Bolliger D, Santer D, Tanaka KA. Heparin-Induced Thrombocytopenia in Patients with Mechanical Circulatory Support. J Cardiothorac Vasc Anesth 2022; 36:1880-1882. [DOI: 10.1053/j.jvca.2022.03.043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 11/11/2022]
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8
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Warkentin TE. Platelet-activating anti-PF4 disorders: an overview. Semin Hematol 2022; 59:59-71. [DOI: 10.1053/j.seminhematol.2022.02.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 11/11/2022]
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9
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Giles JB, Miller EC, Steiner HE, Karnes JH. Elucidation of Cellular Contributions to Heparin-Induced Thrombocytopenia Using Omic Approaches. Front Pharmacol 2022; 12:812830. [PMID: 35126147 PMCID: PMC8814424 DOI: 10.3389/fphar.2021.812830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 12/31/2021] [Indexed: 11/23/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is an unpredictable, complex, immune-mediated adverse drug reaction associated with a high mortality. Despite decades of research into HIT, fundamental knowledge gaps persist regarding HIT likely due to the complex and unusual nature of the HIT immune response. Such knowledge gaps include the identity of a HIT immunogen, the intrinsic roles of various cell types and their interactions, and the molecular basis that distinguishes pathogenic and non-pathogenic PF4/heparin antibodies. While a key feature of HIT, thrombocytopenia, implicates platelets as a seminal cell fragment in HIT pathogenesis, strong evidence exists for critical roles of multiple cell types. The rise in omic technologies over the last decade has resulted in a number of agnostic, whole system approaches for biological research that may be especially informative for complex phenotypes. Applying multi-omics techniques to HIT has the potential to bring new insights into HIT pathophysiology and identify biomarkers with clinical utility. In this review, we review the clinical, immunological, and molecular features of HIT with emphasis on key cell types and their roles. We then address the applicability of several omic techniques underutilized in HIT, which have the potential to fill knowledge gaps related to HIT biology.
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Affiliation(s)
- Jason B. Giles
- Department of Pharmacy Practice and Science, University of Arizona College of Pharmacy, Tucson, AZ, United States
| | - Elise C. Miller
- Department of Pharmacy Practice and Science, University of Arizona College of Pharmacy, Tucson, AZ, United States
| | - Heidi E. Steiner
- Department of Pharmacy Practice and Science, University of Arizona College of Pharmacy, Tucson, AZ, United States
| | - Jason H. Karnes
- Department of Pharmacy Practice and Science, University of Arizona College of Pharmacy, Tucson, AZ, United States,Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, United States,*Correspondence: Jason H. Karnes,
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10
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HLA and PF4 antibody production after adenoviral vector SARS-CoV-2 vaccination. Curr Res Transl Med 2021; 69:103312. [PMID: 34563798 PMCID: PMC8445795 DOI: 10.1016/j.retram.2021.103312] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 09/13/2021] [Indexed: 11/29/2022]
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Islam A, Bashir MS, Joyce K, Rashid H, Laher I, Elshazly S. An Update on COVID-19 Vaccine Induced Thrombotic Thrombocytopenia Syndrome and Some Management Recommendations. Molecules 2021; 26:5004. [PMID: 34443589 PMCID: PMC8400504 DOI: 10.3390/molecules26165004] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/08/2021] [Accepted: 08/13/2021] [Indexed: 12/25/2022] Open
Abstract
The thrombotic thrombocytopenia syndrome (TTS), a complication of COVID-19 vaccines, involves thrombosis (often cerebral venous sinus thrombosis) and thrombocytopenia with occasional pulmonary embolism and arterial ischemia. TTS appears to mostly affect females aged between 20 and 50 years old, with no predisposing risk factors conclusively identified so far. Cases are characterized by thrombocytopenia, higher levels of D-dimers than commonly observed in venous thromboembolic events, inexplicably low fibrinogen levels and worsening thrombosis. Hyper fibrinolysis associated with bleeding can also occur. Antibodies that bind platelet factor 4, similar to those associated with heparin-induced thrombocytopenia, have also been identified but in the absence of patient exposure to heparin treatment. A number of countries have now suspended the use of adenovirus-vectored vaccines for younger individuals. The prevailing opinion of most experts is that the risk of developing COVID-19 disease, including thrombosis, far exceeds the extremely low risk of TTS associated with highly efficacious vaccines. Mass vaccination should continue but with caution. Vaccines that are more likely to cause TTS (e.g., Vaxzevria manufactured by AstraZeneca) should be avoided in younger patients for whom an alternative vaccine is available.
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Affiliation(s)
- Amin Islam
- Department of Haematology, Mid & South Essex University Hospital NHS Foundation Trust, Prittlewell Chase, Westcliff-on-Sea SS0 0RY, UK; (M.S.B.); (K.J.); (S.E.)
- Department of Haematology, Queen Mary University of London, Mile End Road, London E1 3NS, UK
| | - Mohammed Sheraz Bashir
- Department of Haematology, Mid & South Essex University Hospital NHS Foundation Trust, Prittlewell Chase, Westcliff-on-Sea SS0 0RY, UK; (M.S.B.); (K.J.); (S.E.)
| | - Kevin Joyce
- Department of Haematology, Mid & South Essex University Hospital NHS Foundation Trust, Prittlewell Chase, Westcliff-on-Sea SS0 0RY, UK; (M.S.B.); (K.J.); (S.E.)
| | - Harunor Rashid
- National Centre for Immunisation Research and Surveillance(NCIRS) Kids Research, The Children’s Hospital at Westmead, Westmead, NSW 2145, Australia;
- The Discipline of Child and Adolescent Health, Faculty of Medicine and Health, The University of Sydney, Camperdown, NSW 2145, Australia
| | - Ismail Laher
- Department of Anesthesiology, Pharmacology & Therapeutics, Faculty of Medicine, The University of British Colombia, Vancouver, BC V6T 1Z3, Canada;
| | - Shereen Elshazly
- Department of Haematology, Mid & South Essex University Hospital NHS Foundation Trust, Prittlewell Chase, Westcliff-on-Sea SS0 0RY, UK; (M.S.B.); (K.J.); (S.E.)
- Adult Haemato-Oncology Unit, Faculty of Medicne, Ainshams University, Cairo 11566, Egypt
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12
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Warkentin TE, Greinacher A. Spontaneous HIT syndrome: Knee replacement, infection, and parallels with vaccine-induced immune thrombotic thrombocytopenia. Thromb Res 2021; 204:40-51. [PMID: 34144250 DOI: 10.1016/j.thromres.2021.05.018] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/26/2021] [Accepted: 05/28/2021] [Indexed: 12/21/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is characterized clinically by thrombocytopenia, hypercoagulability, and increased thrombosis risk, and serologically by platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies. Heparin-"induced" acknowledges that HIT is usually triggered by a proximate immunizing exposure to heparin. However, certain non-heparin medications (pentosan polysulfate, hypersulfated chondroitin sulfate, fondaparinux) can trigger "HIT". Further, naturally-occurring polyanions (bacterial lipopolysaccharide, DNA/RNA) can interact with PF4 to recapitulate HIT antigens. Indeed, immunologic presensitization to naturally-occurring polyanions could explain why HIT more closely resembles a secondary, rather than a primary, immune response. In 2008 it was first reported that a HIT-mimicking disorder can occur without any preceding exposure to heparin or polyanionic medications. Termed "spontaneous HIT syndrome", two subtypes are recognized: (a) surgical (post-orthopedic, especially post-total knee arthroplasty, and (b) medical (usually post-infectious). Recently, COVID-19 adenoviral vector vaccination has been associated with a thrombotic thrombocytopenic disorder associated with positive PF4-dependent enzyme-immunoassays and serum-induced platelet activation that is maximal when PF4 is added. Vaccine-induced immune thrombotic thrombocytopenia (VITT) features unusual thromboses (cerebral venous thrombosis, splanchnic vein thrombosis) similar to those seen in spontaneous HIT syndrome. The emerging concept is that classic HIT reflects platelet-activating anti-PF4/heparin antibodies whereas spontaneous HIT syndrome and other atypical "autoimmune HIT" presentations (delayed-onset HIT, persisting HIT, heparin "flush" HIT) reflect heparin-independent platelet-activating anti-PF4 antibodies-although the precise relationships between PF4 epitope targets and the clinical syndromes remain to be determined. Treatment of spontaneous HIT syndrome includes non-heparin anticoagulation (direct oral Xa inhibitors favored over direct thrombin inhibitors) and high-dose immunoglobulin.
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Affiliation(s)
- Theodore E Warkentin
- Department of Pathology and Molecular Medicine, and Department of Medicine, McMaster University, Hamilton, Ontario, Canada; Hamilton Regional Laboratory Medicine Program (Transfusion Medicine), Hamilton, Ontario, Canada; Service of Benign Hematology, Hamilton Health Sciences (Hamilton General Hospital), Canada.
| | - Andreas Greinacher
- From Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
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Zhang P, Zhang Y, Pan M, Liu Z, Li J, Peng L, Zhou J, Hu C, Liu S, Zeng X, Ge W, Zhang W. Proteomic analyses of plasma-derived exosomes in immunoglobulin (Ig) G4-related disease and their potential roles in B cell differentiation and tissue damage. J Autoimmun 2021; 122:102650. [PMID: 34107438 DOI: 10.1016/j.jaut.2021.102650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/28/2021] [Accepted: 04/29/2021] [Indexed: 01/06/2023]
Abstract
OBJECTIVE To investigate the proteomic profiles of plasma exosomes isolated from patients with immunoglobulin (Ig) G4-related disease (IgG4-RD) and to determine their potential roles in B cell differentiation and tissue damage. METHODS One hundred untreated IgG4-RD patients and 135 sex- and age-matched healthy controls (HCs) were enrolled in this study. A combination of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and tandem mass tag (TMT)-label quantitation was used for proteomic profiling. Differentially expressed proteins were validated by Western blot, enzyme-linked immunosorbent assay (ELISA) and real-time quantitative PCR (RT-qPCR) analyses. B cell activation, apoptosis, differentiation and reactive oxygen species (ROS) production were analyzed by flow cytometry. We also analyzed the correlations between differentially expressed complement proteins and laboratory parameters. RESULTS A total of 178 differentially expressed proteins were identified in plasma exosomes in IgG4-RD patients compared with HCs, and these proteins were enriched predominantly in the complement cascade pathway. Furthermore, reduced expression levels of complement components C3 and C5 in IgG4-RD were correlated with clinical parameters. Following stimulation with IgG4-RD plasma exosomes, the percentages of naïve B cells decreased, while those of memory B cells and plasmablasts increased; the levels of cytochrome c, somatic (CYCS) and downstream complement system activation also increased. Moreover, ROS production was greater in B cells of IgG4-RD patients than in those of HCs. In affected submandibular glands, the BCR signalling pathway was activated, and exosomes were enriched. CONCLUSION Proteomic profiling revealed that plasma exosome proteins may participate in the pathogenesis of IgG4-RD through complement activation and may be involved in B cell differentiation and activation of the B cell auto-oxidative damage pathway.
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Affiliation(s)
- Panpan Zhang
- Department of Rheumatology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, National Clinical Research Center for Dermatologic and Immunologic Diseases, State Key Laboratory of Complex Severe and Rare Diseases, Beijing, China; Department of Rheumatology and Immunology, The First Affiliated Hospital of Zhengzhou University, No. 1, Jianshe East Road, Zhengzhou, Henan Province, China
| | - Yusheng Zhang
- State Key Laboratory of Medical Molecular Biology & Department of Immunology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Meng Pan
- State Key Laboratory of Medical Molecular Biology & Department of Immunology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China
| | - Zheng Liu
- Department of Rheumatology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, National Clinical Research Center for Dermatologic and Immunologic Diseases, State Key Laboratory of Complex Severe and Rare Diseases, Beijing, China
| | - Jieqiong Li
- Department of Rheumatology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, National Clinical Research Center for Dermatologic and Immunologic Diseases, State Key Laboratory of Complex Severe and Rare Diseases, Beijing, China
| | - Linyi Peng
- Department of Rheumatology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, National Clinical Research Center for Dermatologic and Immunologic Diseases, State Key Laboratory of Complex Severe and Rare Diseases, Beijing, China
| | - Jiaxin Zhou
- Department of Rheumatology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, National Clinical Research Center for Dermatologic and Immunologic Diseases, State Key Laboratory of Complex Severe and Rare Diseases, Beijing, China
| | - Chaojun Hu
- Department of Rheumatology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, National Clinical Research Center for Dermatologic and Immunologic Diseases, State Key Laboratory of Complex Severe and Rare Diseases, Beijing, China
| | - Shengyun Liu
- Department of Rheumatology and Immunology, The First Affiliated Hospital of Zhengzhou University, No. 1, Jianshe East Road, Zhengzhou, Henan Province, China
| | - Xiaofeng Zeng
- Department of Rheumatology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, National Clinical Research Center for Dermatologic and Immunologic Diseases, State Key Laboratory of Complex Severe and Rare Diseases, Beijing, China
| | - Wei Ge
- State Key Laboratory of Medical Molecular Biology & Department of Immunology, Institute of Basic Medical Sciences Chinese Academy of Medical Sciences, School of Basic Medicine Peking Union Medical College, Beijing, China.
| | - Wen Zhang
- Department of Rheumatology, Peking Union Medical College Hospital, Chinese Academy of Medical Science & Peking Union Medical College, National Clinical Research Center for Dermatologic and Immunologic Diseases, State Key Laboratory of Complex Severe and Rare Diseases, Beijing, China.
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Goldman M, Hermans C. Thrombotic thrombocytopenia associated with COVID-19 infection or vaccination: Possible paths to platelet factor 4 autoimmunity. PLoS Med 2021; 18:e1003648. [PMID: 34029337 PMCID: PMC8153497 DOI: 10.1371/journal.pmed.1003648] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Revised: 05/26/2021] [Indexed: 12/13/2022] Open
Abstract
Michel Goldman and Cédric Hermans discuss thrombotic mechanisms in COVID-19 and rare adverse reactions to SARS-CoV-2 vaccinations.
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Affiliation(s)
- Michel Goldman
- Institute for Interdisciplinary Innovation in Healthcare, Université libre de Bruxelles (ULB), Brussels, Belgium
| | - Cédric Hermans
- Division of Hematology, Hemostasis and Thrombosis Unit, Saint-Luc University Hospital, Université catholique de Louvain (UCLouvain), Brussels, Belgium
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15
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Heparin-Induced Thrombocytopenia: A Review of New Concepts in Pathogenesis, Diagnosis, and Management. J Clin Med 2021; 10:jcm10040683. [PMID: 33578859 PMCID: PMC7916628 DOI: 10.3390/jcm10040683] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/29/2021] [Accepted: 01/30/2021] [Indexed: 12/17/2022] Open
Abstract
Knowledge on heparin-induced thrombocytopenia keeps increasing. Recent progress on diagnosis and management as well as several discoveries concerning its pathogenesis have been made. However, many aspects of heparin-induced thrombocytopenia remain partly unknown, and exact application of these new insights still need to be addressed. This article reviews the main new concepts in pathogenesis, diagnosis, and management of heparin-induced thrombocytopenia.
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16
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Gaunt ER, Mabbott NA. The clinical correlates of vaccine-induced immune thrombotic thrombocytopenia after immunisation with adenovirus vector-based SARS-CoV-2 vaccines. IMMUNOTHERAPY ADVANCES 2021; 1:ltab019. [PMID: 34557868 PMCID: PMC8385946 DOI: 10.1093/immadv/ltab019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/04/2021] [Accepted: 08/16/2021] [Indexed: 12/13/2022] Open
Abstract
We are at a critical stage in the COVID-19 pandemic where vaccinations are being rolled out globally, in a race against time to get ahead of the SARS-CoV-2 coronavirus and the emergence of more highly transmissible variants. A range of vaccines have been created and received either emergency approval or full licensure. To attain the upper hand, maximum vaccine synthesis, deployment, and uptake as rapidly as possible is essential. However, vaccine uptake, particularly in younger adults is dropping, at least in part fuelled by reports of rare complications associated with specific vaccines. This review considers how vaccination with adenovirus vector-based vaccines against the SARS-CoV-2 coronavirus might cause rare cases of thrombosis and thrombocytopenia in some recipients. A thorough understanding of the underlying cellular and molecular mechanisms that mediate this syndrome may help to identify methods to prevent these very rare, but serious side effects. This will also help facilitate the identification of those at highest risk from these outcomes, so that we can work towards a stratified approach to vaccine deployment to mitigate these risks.
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Affiliation(s)
- Eleanor R Gaunt
- The Roslin Institute & Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Neil A Mabbott
- The Roslin Institute & Royal (Dick) School of Veterinary Studies, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
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17
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Arepally GM, Cines DB. Pathogenesis of heparin-induced thrombocytopenia. Transl Res 2020; 225:131-140. [PMID: 32417430 PMCID: PMC7487042 DOI: 10.1016/j.trsl.2020.04.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/15/2020] [Accepted: 04/21/2020] [Indexed: 01/19/2023]
Abstract
There are currently no effective substitutes for high intensity therapy with unfractionated heparin (UFH) for cardiovascular procedures based on its rapid onset of action, ease of monitoring and reversibility. The continued use of UFH in these and other settings requires vigilance for its most serious nonhemorrhagic complication, heparin induced thrombocytopenia (HIT). HIT is an immune prothrombotic disorder caused by antibodies that recognize complexes between platelet factor 4 (PF4) and polyanions such as heparin (H).The pathogenicity of anti-PF4/H antibodies is likely due to the formation of immune complexes that initiate intense procoagulant responses by vascular and hematopoietic cells that lead to the generation of platelet microparticles, monocyte and endothelial cell procoagulant activity, and neutrophil extracellular traps, among other outcomes. The development of anti-PF4/H antibodies after exposure to UFH greatly exceeds the incidence of clinical disease, but the biochemical features that distinguish pathogenic from nonpathogenic antibodies have not been identified. Diagnosis relies on pretest clinical probability, screening for anti-PF4/H antibodies and documentation of their platelet activating capacity. However, both clinical algorithms and test modalities have limited predictive values making diagnosis and management challenging. Given the unacceptable rates of recurrent thromboembolism and bleeding associated with current therapies, there is an unmet need for novel rational nonanticoagulant therapeutics based on the pathogenesis of HIT. We will review recent developments in our understanding of the pathogenesis of HIT and its implications for future approaches to diagnosis and management.
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Affiliation(s)
- Gowthami M Arepally
- Division of Hematology, Duke University Medical Center, Durham, North Carolina.
| | - Douglas B Cines
- Department of Pathology and Laboratory Medicine, Perelman-University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania
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18
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Zhou P, Yin JX, Tao HL, Zhang HW. Pathogenesis and management of heparin-induced thrombocytopenia and thrombosis. Clin Chim Acta 2020; 504:73-80. [DOI: 10.1016/j.cca.2020.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 01/30/2020] [Accepted: 02/03/2020] [Indexed: 01/19/2023]
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19
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Gollomp K, Sarkar A, Harikumar S, Seeholzer SH, Arepally GM, Hudock K, Rauova L, Kowalska MA, Poncz M. Fc-modified HIT-like monoclonal antibody as a novel treatment for sepsis. Blood 2020; 135:743-754. [PMID: 31722003 PMCID: PMC7059515 DOI: 10.1182/blood.2019002329] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 11/03/2019] [Indexed: 12/19/2022] Open
Abstract
Sepsis is characterized by multiorgan system dysfunction that occurs because of infection. It is associated with high morbidity and mortality and is in need of improved therapeutic interventions. Neutrophils play a crucial role in sepsis, releasing neutrophil extracellular traps (NETs) composed of DNA complexed with histones and toxic antimicrobial proteins that ensnare pathogens, but also damage host tissues. At presentation, patients often have a significant NET burden contributing to the multiorgan damage. Therefore, interventions that inhibit NET release would likely be ineffective at preventing NET-based injury. Treatments that enhance NET degradation may liberate captured bacteria and toxic NET degradation products (NDPs) and likely be of limited therapeutic benefit as well. We propose that interventions that stabilize NETs and sequester NDPs may be protective in sepsis. We showed that platelet factor 4 (PF4), a platelet-associated chemokine, binds and compacts NETs, increasing their resistance to DNase I. We now show that PF4 increases NET-mediated bacterial capture, reduces the release of NDPs, and improves outcome in murine models of sepsis. A monoclonal antibody KKO which binds to PF4-NET complexes, further enhances DNase resistance. However, the Fc portion of this antibody activates the immune response and increases thrombotic risk, negating any protective effects in sepsis. Therefore, we developed an Fc-modified KKO that does not induce these negative outcomes. Treatment with this antibody augmented the effects of PF4, decreasing NDP release and bacterial dissemination and increasing survival in murine sepsis models, supporting a novel NET-targeting approach to improve outcomes in sepsis.
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Affiliation(s)
- Kandace Gollomp
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Amrita Sarkar
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Sanjiv Harikumar
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA
| | - Steven H Seeholzer
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | | | - Kristin Hudock
- Department of Internal Medicine, University of Cincinnati School of Medicine, Cincinnati, OH; and
| | - Lubica Rauova
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - M Anna Kowalska
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA
- Institute of Medical Biology, Polish Academy of Science, Lodz, Poland
| | - Mortimer Poncz
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA
- Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
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20
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Complement Signals Determine Opposite Effects of B Cells in Chemotherapy-Induced Immunity. Cell 2020; 180:1081-1097.e24. [PMID: 32142650 DOI: 10.1016/j.cell.2020.02.015] [Citation(s) in RCA: 134] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 12/16/2019] [Accepted: 02/05/2020] [Indexed: 12/21/2022]
Abstract
Understanding molecular mechanisms that dictate B cell diversity is important for targeting B cells as anti-cancer treatment. Through the single-cell dissection of B cell heterogeneity in longitudinal samples of patients with breast cancer before and after neoadjuvant chemotherapy, we revealed that an ICOSL+ B cell subset emerges after chemotherapy. Using three immunocompetent mouse models, we recapitulated the subset switch of human tumor-infiltrating B cells during chemotherapy. By employing B-cell-specific deletion mice, we showed that ICOSL in B cells boosts anti-tumor immunity by enhancing the effector to regulatory T cell ratio. The signature of ICOSL+ B cells is imprinted by complement-CR2 signaling, which is triggered by immunogenic cell death. Moreover, we identified that CD55, a complement inhibitory protein, determines the opposite roles of B cells in chemotherapy. Collectively, we demonstrated a critical role of the B cell subset switch in chemotherapy response, which has implications in designing novel anti-cancer therapies. VIDEO ABSTRACT.
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21
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Maličev E. The use of flow cytometry in the diagnosis of heparin-induced thrombocytopenia (HIT). Transfus Med Rev 2019; 34:34-41. [PMID: 31575433 DOI: 10.1016/j.tmrv.2019.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/21/2019] [Accepted: 08/07/2019] [Indexed: 11/25/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) affects some of the patients exposed to heparin. It is mediated by antibodies that recognize neoepitopes on platelet factor 4 (PF4)/heparin complexes. A HIT diagnosis requires both clinical and laboratory evaluation and remains a challenge. Since many patients develop antibodies in response to heparin, but only a few of them generate anti-PF4/heparin antibodies capable of activating platelets which consequently cause clinical complications, the performance of serologic assays is not enough to diagnose HIT. Functional assays can identify pathogenic antibodies capable of platelet activation, but they are more demanding and their limited availability contributes to the problem of diagnosing HIT. Restricted laboratories usually collect sera of multiple patients to perform functional assays only once or twice a week; hence, a HIT diagnosis can take several days. The use of flow cytometry appears to be a promising alternative in the confirmation of pathogenic anti-PF4/heparin antibodies. Flow cytometric assays detect either activation markers on a healthy donor's platelet surfaces or platelet derived microparticles formed after platelet incubation with a patient's serum. Flow cytometers are readily available in many clinical laboratories, so this technology introduces the possibility of an earlier HIT diagnosis. The objective of this review was to collect findings on flow cytometric HIT confirmations to the present date, and to review the currently available flow cytometric assays used in the diagnosis of HIT.
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Affiliation(s)
- Elvira Maličev
- Blood Transfusion Center of Slovenia, Ljubljana, Slovenia.
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22
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Cipok M, Tomer A, Elalamy I, Kirgner I, Dror N, Kay S, Deutsch VR. Pathogenic heparin-induced thrombocytopenia and thrombosis (HIT) antibodies determined by rapid functional flow cytometry. Eur J Haematol 2019; 103:225-233. [PMID: 31206215 DOI: 10.1111/ejh.13277] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 06/05/2019] [Accepted: 06/06/2019] [Indexed: 11/27/2022]
Abstract
OBJECTIVES Reliable diagnosis of heparin-induced thrombocytopenia and thrombosis (HIT) is mandatory for patient management, yet prompt determination of pathogenic antibodies remains an unmet clinical challenge. Common immunoassays carry inherent limitations and functional assays which detect antibody-mediated platelet activation are not usually readily available to routine laboratories, especially the serotonin release assay (SRA), being technically demanding, time consuming, and requires high level expertise. To overcome some of these limitations, we have developed a practical functional flow cytometric assay (FCA) for routine clinical use. METHODS A simple FCA is described which avoids platelet manipulation, is highly specific and sensitive compared with SRA, and provides rapid results. RESULTS Of the 650 consecutive samples, from HIT-suspected patients, 99 (15.3%) were positive by the PaGIA Heparin/PF4 immunoassay and 31 (4.8%) by FCA. Average platelet activation was 11-fold higher in PaGIA+/FCA+ vs PaGIA-/FCA- samples. Of 21 SRA-positive samples, 19 were FCA-positive (relative sensitivity 90.5%), and of 42 SRA-negative samples, 40 were FCA-negative (relative specificity 95.2%). The FCA showed significantly higher correlation with the clinical presentation of HIT (4Ts score) performed on 182 patients, compared with PaGIA Heparin/PF4 (ROC-plot analysis, AUC 0.93 vs 0.63, P < 0.001). At a 92% sensitivity, the assay specificity was 96%. CONCLUSIONS The present FCA is practical for routine testing, providing prompt reliable results for initial diagnosis and confirmation, to effectively assist in HIT patient management.
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Affiliation(s)
- Michal Cipok
- The Hematology Institute, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Aaron Tomer
- The Hematology Institute, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Ismail Elalamy
- Hematology and Thrombosis Center, Tenon University Hospital, INSERM UMRS 938, Sorbonne University, Paris, France.,Department of Obstetrics and Gynecology, I.M. Sechenov First Moscow State Medical University, Moscow, Russia
| | - Ilya Kirgner
- The Hematology Institute, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Naama Dror
- The Hematology Institute, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Sigi Kay
- The Hematology Institute, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Varda R Deutsch
- The Hematology Institute, Tel Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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23
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Fibronectin: a “double hit” modulator in HIT? Blood 2019; 133:891-892. [DOI: 10.1182/blood-2019-01-894295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
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24
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Heparin-Induced Thrombocytopenia. Platelets 2019. [DOI: 10.1016/b978-0-12-813456-6.00041-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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25
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Khandelwal S, Ravi J, Rauova L, Johnson A, Lee GM, Gilner JB, Gunti S, Notkins AL, Kuchibhatla M, Frank M, Poncz M, Cines DB, Arepally GM. Polyreactive IgM initiates complement activation by PF4/heparin complexes through the classical pathway. Blood 2018; 132:2431-2440. [PMID: 30309891 PMCID: PMC6284214 DOI: 10.1182/blood-2018-03-834598] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 10/06/2018] [Indexed: 11/20/2022] Open
Abstract
The mechanisms by which exposure to heparin initiates antibody responses in many, if not most, recipients are poorly understood. We recently demonstrated that antigenic platelet factor 4 (PF4)/heparin complexes activate complement in plasma and bind to B cells. Here, we describe how this process is initiated. We observed wide stable variation in complement activation when PF4/heparin was added to plasma of healthy donors, indicating a responder "phenotype" (high, intermediate, or low). Proteomic analysis of plasma from these healthy donors showed a strong correlation between complement activation and plasma immunoglobulin M (IgM) levels (r = 0.898; P < .005), but not other Ig isotypes. Complement activation response to PF4/heparin in plasma displaying the low donor phenotype was enhanced by adding pooled IgM from healthy donors, but not monoclonal IgM. Depletion of IgM from plasma abrogated C3c generation by PF4/heparin. The complement-activating features of IgM are likely mediated by nonimmune, or natural, IgM, as cord blood and a monoclonal polyreactive IgM generate C3c in the presence of PF4/heparin. IgM facilitates complement and antigen deposition on B cells in vitro and in patients receiving heparin. Anti-C1q antibody prevents IgM-mediated complement activation by PF4/heparin complexes, indicating classical pathway involvement. These studies demonstrate that variability in plasma IgM levels correlates with functional complement responses to PF4/heparin. Polyreactive IgM binds PF4/heparin, triggers activation of the classical complement pathway, and promotes antigen and complement deposition on B cells. These studies provide new insights into the evolution of the heparin-induced thrombocytopenia immune response and may provide a biomarker of risk.
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Affiliation(s)
| | - Joann Ravi
- Division of Hematology, Duke University Medical Center, Durham, NC
| | - Lubica Rauova
- Children's Hospital of Philadelphia, Philadelphia, PA
| | | | - Grace M Lee
- Division of Hematology, Duke University Medical Center, Durham, NC
| | | | - Sreenivasulu Gunti
- Experimental Medicine Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD
| | - Abner L Notkins
- Experimental Medicine Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD
| | | | - Michael Frank
- Department of Pediatrics, Duke University Medical Center, Durham, NC; and
| | | | - Douglas B Cines
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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26
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Natural, not immune; classical, not alternative. Blood 2018; 132:2421-2422. [PMID: 30523121 DOI: 10.1182/blood-2018-10-880799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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27
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Karnes JH. Pharmacogenetics to prevent heparin-induced thrombocytopenia: what do we know? Pharmacogenomics 2018; 19:1413-1422. [PMID: 30398086 DOI: 10.2217/pgs-2018-0147] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a life-threatening, immune-mediated adverse reaction to heparin anticoagulants. The inability to predict HIT represents a considerable liability associated with heparin administration. Genetic studies of HIT are challenging due to the scarcity of true HIT cases, potential for misclassification, and many environmental risk factors. Genetic studies have not consistently identified risk alleles for HIT, the production of platelet factor 4/heparin antibodies or the thromboembolic complications of HIT. Genes implicated in HIT and platelet factor 4/heparin antibody levels include FCGR2A, TDAG8, HLA-DR and others. Compelling evidence also suggests that the FCGR2A H131R polymorphism is associated with HIT-related thrombosis. There is a need for well-powered, multiethnic studies with laboratory confirmation of HIT, detailed patient- and drug-specific data, and inclusion of both serologic and thromboembolic outcomes. Genomic biomarkers identified from such studies offer the possibility of shifting current clinical practice paradigms from early detection and treatment to prevention.
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Affiliation(s)
- Jason H Karnes
- Department of Pharmacy Practice & Science, University of Arizona College of Pharmacy, Tucson, AZ 85721, USA.,Sarver Heart Center, Department of Medicine, University of Arizona College of Medicine - Tucson, Tucson, AZ 85721, USA.,Division of Pharmacogenomics, Center for Applied Genetics & Genomic Medicine (TCAG2M), Department of Medicine, University of Arizona College of Medicine - Tucson, Tucson, AZ 85721, USA
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28
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Maharaj S, Chang S, Seegobin K, Morales J, Aysola A, Rana F, Shaikh M. Temporality of heparin-induced antibodies: a retrospective study in outpatients undergoing hemodialysis on unfractionated heparin. Exp Hematol Oncol 2018; 7:23. [PMID: 30221035 PMCID: PMC6137914 DOI: 10.1186/s40164-018-0115-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 09/06/2018] [Indexed: 01/27/2023] Open
Abstract
Background Heparin-induced antibodies (HIA) are responsible for causing heparin-induced thrombocytopenia and thrombosis. Research has shown that the temporality of heparin-induced antibodies does not follow the classic immunologic response. The immunobiology of HIA generation remains unclear with varying in vitro and in vivo data. Outpatients undergoing hemodialysis (HD) are exposed to heparin chronically. The HIA immune response can therefore be investigated in vivo in this population. Methods We examined the time between the start of HD using unfractionated heparin and HIA levels in 212 outpatients during a 6-year period. Antibodies were detected on enzyme-linked immunosorbent assay. HIA levels were analyzed to determine significance of the trend over time. HIA subgroups were also analyzed for correlation with subsequent thrombotic events and platelet count during follow up. Results Overall, the HIA response in HD was found to peak early with waning antibody response despite continued exposure to heparin. The peak prevalence of a strong immune response (optical density > 1.000) was early and short lived, while weaker immune response (optical density 0.400–1.000) persisted for the first 6 months then declined. The mean follow-up time per patient was 2.3 ± 1.4 years. Despite circulating HIA, including high titers, no patients developed HIT in this sample. There was no association between HIA and thrombocytopenia. There was increased incidence of thrombosis in patients with strong HIA compared to other groups, but this did not achieve statistical significance. Conclusions The data suggest a significant temporal pattern of HIA in outpatients undergoing HD using unfractionated heparin. Positive HIA was not found to be significantly associated with thrombocytopenia or thrombosis risk in these patients. However, while not achieving statistical significance, subsequent thrombotic events occurred most frequently in the strong positive HIA group (optical density > 1.000). Further research into HIA and risk of thrombosis in this population is needed.
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Affiliation(s)
- Satish Maharaj
- 1Division of Hematology and Medical Oncology, Department of Internal Medicine, University of Florida College of Medicine-Jacksonville, UF Health Jacksonville, 653 W 8th St, Jacksonville, FL 32209 USA
| | - Simone Chang
- 2University of Miami Health System, Miami, FL USA
| | - Karan Seegobin
- 1Division of Hematology and Medical Oncology, Department of Internal Medicine, University of Florida College of Medicine-Jacksonville, UF Health Jacksonville, 653 W 8th St, Jacksonville, FL 32209 USA
| | - James Morales
- 1Division of Hematology and Medical Oncology, Department of Internal Medicine, University of Florida College of Medicine-Jacksonville, UF Health Jacksonville, 653 W 8th St, Jacksonville, FL 32209 USA
| | - Agnes Aysola
- 1Division of Hematology and Medical Oncology, Department of Internal Medicine, University of Florida College of Medicine-Jacksonville, UF Health Jacksonville, 653 W 8th St, Jacksonville, FL 32209 USA
| | - Fauzia Rana
- 1Division of Hematology and Medical Oncology, Department of Internal Medicine, University of Florida College of Medicine-Jacksonville, UF Health Jacksonville, 653 W 8th St, Jacksonville, FL 32209 USA
| | - Marwan Shaikh
- 1Division of Hematology and Medical Oncology, Department of Internal Medicine, University of Florida College of Medicine-Jacksonville, UF Health Jacksonville, 653 W 8th St, Jacksonville, FL 32209 USA
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Rauova L, Arepally G, Poncz M, Cines DB. Molecular and cellular pathogenesis of heparin-induced thrombocytopenia (HIT). Autoimmun Rev 2018; 17:1046-1052. [PMID: 30103043 DOI: 10.1016/j.autrev.2018.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 05/09/2018] [Indexed: 01/19/2023]
Affiliation(s)
- Lubica Rauova
- Division of Hematology, Department of Pediatrics, Childrens Hospital of Philadelphia, USA; Department of Pediatrics, University of Pennsylvania, Perelman School of Medicine, USA
| | - Gowthami Arepally
- Division of Hematology, Department of Medicine, Duke University School of Medicine, USA
| | - Mortimer Poncz
- Division of Hematology, Department of Pediatrics, Childrens Hospital of Philadelphia, USA; Department of Pediatrics, University of Pennsylvania, Perelman School of Medicine, USA
| | - Douglas B Cines
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Perelman School of Medicine, USA; Department of Medicine, University of Pennsylvania, Perelman School of Medicine, USA.
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30
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Khandelwal S, Johnson AM, Liu J, Keire D, Sommers C, Ravi J, Lee GM, Lambris JD, Reis ES, Arepally GM. Novel Immunoassay for Complement Activation by PF4/Heparin Complexes. Thromb Haemost 2018; 118:1484-1487. [PMID: 29960275 DOI: 10.1055/s-0038-1660858] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Sanjay Khandelwal
- Division of Hematology, Duke University Medical Center, Duke University, Durham, North Carolina, United States
| | - Alexandra M Johnson
- Division of Hematology, Duke University Medical Center, Duke University, Durham, North Carolina, United States
| | - Jian Liu
- Division of Chemical Biology & Medicinal Chemistry, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, North Carolina, United States
| | - David Keire
- Division of Pharmaceutical Analysis, CDER, Food and Drug Administration, St Louis, Missouri, United States
| | - Cynthia Sommers
- Division of Pharmaceutical Analysis, CDER, Food and Drug Administration, St Louis, Missouri, United States
| | - Joann Ravi
- Division of Hematology, Duke University Medical Center, Duke University, Durham, North Carolina, United States
| | - Grace M Lee
- Division of Hematology, Duke University Medical Center, Duke University, Durham, North Carolina, United States
| | - John D Lambris
- Department of Pathology & Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Edimara S Reis
- Department of Pathology & Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States
| | - Gowthami M Arepally
- Division of Hematology, Duke University Medical Center, Duke University, Durham, North Carolina, United States
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31
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Complement links platelets to innate immunity. Semin Immunol 2018; 37:43-52. [DOI: 10.1016/j.smim.2018.01.003] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 01/30/2018] [Accepted: 01/31/2018] [Indexed: 12/11/2022]
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Abstract
There are numerous congenital and acquired causes of thrombocytopenia. Thrombocytopenia could be a result of decreased bone marrow production, increased consumption, increased destruction, splenic sequestration or a combination of these causes. In this review, we have focused on some of the serious acquired causes of thrombocytopenia. There have been some significant advances in our understanding of the pathophysiology, diagnostic testing, and treatment of immune thrombocytopenia, heparin-induced thrombocytopenia, thrombotic thrombocytopenic purpura, and atypical hemolytic uremic syndrome over the past five years. These advances have resulted in a significant decrease in mortality and morbidity of patients with these disorders. Despite these advances, we are still faced with numerous unanswered questions in the pathophysiology and management of these complex thrombocytopenic disorders.
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Affiliation(s)
- Srikanth Nagalla
- Division of Hematology/Oncology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Ravindra Sarode
- Division of Transfusion Medicine and Hemostasis, Department of Pathology, UT Southwestern Medical Center, Dallas, TX, USA
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33
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Rice L. HITs and misses in 100 years of heparin. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2017; 2017:667-673. [PMID: 29222319 PMCID: PMC6142618 DOI: 10.1182/asheducation-2017.1.667] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Heparin was discovered 100 years ago, and the heparin-induced thrombocytopenia syndrome was described 40 years ago. That the most powerful anticoagulant of the last century can also produce the most extreme prothrombotic diathesis is but one of the paradoxes that surround heparin-induced thrombocytopenia. Standard treatment is alternative anticoagulation. Advances continue to be made regarding pathophysiology, prevention, and treatment. Currently, an epidemic of overdiagnosis threatens the well-being of patients, so efforts to educate clinicians on when and how to make this diagnosis are pressing.
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Affiliation(s)
- Lawrence Rice
- Hematology Division, Department of Medicine, Houston Methodist Hospital, Weill Cornell Medical College, Houston, TX
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34
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Abstract
Heparin-induced thrombocytopenia (HIT) is an immune complication of heparin therapy caused by antibodies to complexes of platelet factor 4 (PF4) and heparin. Pathogenic antibodies to PF4/heparin bind and activate cellular FcγRIIA on platelets and monocytes to propagate a hypercoagulable state culminating in life-threatening thrombosis. It is now recognized that anti-PF4/heparin antibodies develop commonly after heparin exposure, but only a subset of sensitized patients progress to life-threatening complications of thrombocytopenia and thrombosis. Recent scientific developments have clarified mechanisms underlying PF4/heparin immunogenicity, disease susceptibility, and clinical manifestations of disease. Insights from clinical and laboratory findings have also been recently harnessed for disease prevention. This review will summarize our current understanding of HIT by reviewing pathogenesis, essential clinical and laboratory features, and management.
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35
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Staibano P, Arnold DM, Bowdish DME, Nazy I. The unique immunological features of heparin-induced thrombocytopenia. Br J Haematol 2017; 177:198-207. [DOI: 10.1111/bjh.14603] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Phillip Staibano
- Department of Medicine; Michael G. DeGroote School of Medicine; McMaster University; Hamilton ON Canada
| | - Donald M. Arnold
- Department of Medicine; Michael G. DeGroote School of Medicine; McMaster University; Hamilton ON Canada
- Canadian Blood Services; Hamilton ON Canada
| | - Dawn M. E. Bowdish
- McMaster Immunology Research Centre; McMaster University; Hamilton ON Canada
| | - Ishac Nazy
- Department of Medicine; Michael G. DeGroote School of Medicine; McMaster University; Hamilton ON Canada
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36
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Hayes V, Johnston I, Arepally GM, McKenzie SE, Cines DB, Rauova L, Poncz M. Endothelial antigen assembly leads to thrombotic complications in heparin-induced thrombocytopenia. J Clin Invest 2017; 127:1090-1098. [PMID: 28218620 DOI: 10.1172/jci90958] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 12/06/2016] [Indexed: 01/27/2023] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder initiated by antibodies against complexes between human platelet factor 4 (hPF4) and heparin. A better understanding of the events that initiate the prothrombotic state may improve approaches to antithrombotic management. Here, we visualized thrombus formation in an in vivo murine model and an endothelialized microfluidic system that simulate the pathogenesis of HIT. hPF4 released from platelets predominantly bound to peri-injury endothelium and formed HIT antigenic complexes that were dissociated by heparin. In mice expressing both hPF4+ and human platelet IgG Fc receptor IIA (FcγRIIA), infusion of the HIT-like monoclonal antibody KKO increased fibrin and platelet deposition at sites of injury, followed immediately by antigen formation on proximate endothelial cells. After a few minutes, HIT antigen was detected within the thrombus itself at the interface between the platelet core and the surrounding shell. We observed similar results in the humanized, endothelialized microfluidic system. hPF4 and KKO selectively bound to photochemically injured endothelium at sites where surface glycocalyx was reduced. These studies support the concept that the perithrombus endothelium is the predominant site of HIT antigen assembly. This suggests that disrupting antigen formation along the endothelium or protecting the endothelium may provide a therapeutic opportunity to prevent thrombotic complications of HIT, while sparing systemic hemostatic pathways.
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37
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Onwuemene O, Arepally GM. Heparin-induced thrombocytopenia: research and clinical updates. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2016; 2016:262-268. [PMID: 27913490 PMCID: PMC6142447 DOI: 10.1182/asheducation-2016.1.262] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Heparin-induced thrombocytopenia (HIT) remains an important diagnosis to consider in hospitalized patients developing thrombocytopenia. HIT is an immune-mediated prothrombotic disorder caused by antibodies to platelet factor 4 (PF4) and heparin. Recent basic scientific studies have advanced our understanding of disease pathogenesis through studies of the PF4/heparin structure, immune mechanisms, and cellular basis of thrombosis. Clinical advances have also occurred in areas of HIT prevention, description of disease variants, and diagnostic strategies. Emerging anticoagulants with the potential to change HIT treatment are evolving, although with limited data. This review will provide a current perspective on HIT pathogenesis, disease features, diagnostic strategies, and role of emerging therapies for the management of HIT.
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Affiliation(s)
- Oluwatoyosi Onwuemene
- Division of Hematology, Department of Medicine, Duke University Medical Center, Durham, NC
| | - Gowthami M Arepally
- Division of Hematology, Department of Medicine, Duke University Medical Center, Durham, NC
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38
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Polyphosphate/platelet factor 4 complexes can mediate heparin-independent platelet activation in heparin-induced thrombocytopenia. Blood Adv 2016; 1:62-74. [PMID: 29296696 DOI: 10.1182/bloodadvances.2016000877] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 10/03/2016] [Indexed: 01/01/2023] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a thrombotic disorder initiated by antibodies to complexes between platelet factor 4 (PF4) and heparin. The risk of recurrent thromboembolism persists after heparin is cleared and platelet activation leading to release of PF4 has dissipated. We asked whether antigenic complexes between polyphosphates and PF4 released from activated platelets might intensify or sustain the prothrombotic phenotype of HIT. PF4 forms stable, ultralarge complexes with polyphosphates of various sizes, including those released from platelets, which are recognized by the HIT-like monoclonal KKO, an immunoglobulin G2bκ monoclonal heparin/PF4 binding antibody, and by human HIT antibodies. KKO helps to protect PF4/polyphosphate complexes from degradation by phosphatases. Complement is activated when HIT antibodies bind to PF4/polyphosphate complexes and PF4 reverses the inhibition of complement by polyphosphates. Polyphosphates and PF4 are stored primarily in separate granules in resting platelets, but they colocalize when the cells are activated. Platelets activated by subaggregating doses of thrombin receptor activating peptide release polyphosphates and PF4, which form antigenic complexes that allow KKO to further activate platelets in the absence of heparin and exogenous PF4. These studies suggest that thrombin- or immune complex-mediated release of endogenous antigenic PF4/polyphosphate complexes from platelets may augment the prothrombotic risk of HIT and perpetuate the risk of thrombosis after heparin has been discontinued.
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B cells, PF4/heparin complexes, and complement. Blood 2016; 128:1781-1782. [PMID: 28832327 DOI: 10.1182/blood-2016-08-729517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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