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Mukherjee A, Gentille C, Patel A, Ensor J, Rice L. Heparin-induced thrombocytopenia with very high antibody titer is associated with slower platelet recovery and higher risk of thrombosis. Int J Hematol 2024; 120:290-296. [PMID: 38976179 DOI: 10.1007/s12185-024-03811-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Revised: 06/06/2024] [Accepted: 06/24/2024] [Indexed: 07/09/2024]
Abstract
Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder mediated by platelet-activating antibodies targeting platelet factor 4 (PF4) and heparin complex. A higher antibody titer is reflected in a higher optical density (OD) by enzyme-linked immunosorbent assay for heparin-PF4 antibodies. This single-institution retrospective study of 116 HIT patients examined the effect of heparin-PF4 OD on time to platelet recovery, vascular thrombosis, and in-hospital mortality. Patients were divided into 3 cohorts based on heparin-PF4 OD: cohort 1 had an OD ≥ 2 and ≤ 2.4, cohort 2 had an OD > 2.4 and ≤ 2.8, and cohort 3 had an OD > 2.8. A higher OD titer was associated with significantly increased time to platelet recovery when compared between cohorts 1 versus 2 (HR = 0.599, p = 0.0221) and 1 versus 3 (HR = 0.515, p = 0.0014), as well as an increased risk of thrombosis (79.4%-cohort 3 vs 53.8%-cohort 2 vs 46.1%-cohort 1, p = 0.04), but had no impact on mortality (2.62-alive vs 2.65-deceased, p = 0.7432). A higher OD titer can inform risk assessment and support decision-making in HIT patients; however, prospective studies are needed to further clarify the impact of heparin-PF4 OD on outcomes.
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Affiliation(s)
- Akash Mukherjee
- Department of Hematology and Oncology, Houston Methodist Hospital, Houston, TX, USA
| | - Cesar Gentille
- Department of Hematology and Oncology, Houston Methodist Hospital, Houston, TX, USA.
| | - Asmita Patel
- Department of Hematology and Oncology, Global Cancer Research Institute, San Jose, CA, USA
| | - Joe Ensor
- Department of Hematology and Oncology, Houston Methodist Hospital, Houston, TX, USA
| | - Lawrence Rice
- Department of Hematology and Oncology, Houston Methodist Hospital, Houston, TX, USA
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2
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Abrams ST, Du M, Shaw RJ, Johnson C, McGuinness D, Schofield J, Yong J, Turtle L, Nicolson PLR, Moxon C, Wang G, Toh CH. Damage-associated cellular markers in the clinical and pathogenic profile of vaccine-induced immune thrombotic thrombocytopenia. J Thromb Haemost 2024; 22:1145-1153. [PMID: 38103733 DOI: 10.1016/j.jtha.2023.12.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Revised: 12/01/2023] [Accepted: 12/02/2023] [Indexed: 12/19/2023]
Abstract
BACKGROUND Adenoviral vector-based COVID-19 vaccine-induced immune thrombotic thrombocytopenia (VITT) is rare but carries significant risks of mortality and long-term morbidity. The underlying pathophysiology of severe disease is still not fully understood. The objectives were to explore the pathophysiological profile and examine for clinically informative biomarkers in patients with severe VITT. METHODS Twenty-two hospitalized patients with VITT, 9 pre- and 21 post-ChAdOx1 vaccine controls, were recruited across England, United Kingdom. Admission blood samples were analyzed for cytokine profiles, cell death markers (lactate dehydrogenase and circulating histones), neutrophil extracellular traps, and coagulation parameters. Tissue specimens from deceased patients were analyzed. RESULTS There were strong immune responses characterized by significant elevations in proinflammatory cytokines and T helper 1 and 2 cell activation in patients with VITT. Markers of systemic endothelial activation and coagulation activation in both circulation and organ sections were also significantly elevated. About 70% (n = 15/22) of patients met the International Society for Thrombosis and Haemostasis criteria for disseminated intravascular coagulation despite negligible changes in the prothrombin time. The increased neutrophil extracellular trap formation, in conjunction with marked lymphopenia, elevated lactate dehydrogenase, and circulating histone levels, indicates systemic immune cell injury or death. Both lymphopenia and circulating histone levels independently predicted 28-day mortality in patients with VITT. CONCLUSION The coupling of systemic cell damage and death with strong immune-inflammatory and coagulant responses are pathophysiologically dominant and clinically relevant in severe VITT.
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Affiliation(s)
- Simon T Abrams
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, United Kingdom; Haematology Department, Liverpool University Hospitals National Health Service Foundation Trust, Liverpool, United Kingdom
| | - Min Du
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, United Kingdom
| | - Rebecca J Shaw
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, United Kingdom; Roald Dahl Haemostasis and Thrombosis Centre, Liverpool University Hospitals National Health Service Foundation Trust, Liverpool, United Kingdom
| | - Carla Johnson
- School of Infection and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland
| | - Dagmara McGuinness
- School of Infection and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland
| | - Jeremy Schofield
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, United Kingdom; Roald Dahl Haemostasis and Thrombosis Centre, Liverpool University Hospitals National Health Service Foundation Trust, Liverpool, United Kingdom
| | - Jun Yong
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, United Kingdom; Roald Dahl Haemostasis and Thrombosis Centre, Liverpool University Hospitals National Health Service Foundation Trust, Liverpool, United Kingdom
| | - Lance Turtle
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, United Kingdom
| | - Phillip L R Nicolson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom; Haemophilia Comprehensive Care Centre, Queen Elizabeth Hospital, University Hospitals Birmingham National Health Service Foundation Trust, Birmingham, United Kingdom
| | - Christopher Moxon
- School of Infection and Immunity, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland
| | - Guozheng Wang
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, United Kingdom; Haematology Department, Liverpool University Hospitals National Health Service Foundation Trust, Liverpool, United Kingdom.
| | - Cheng-Hock Toh
- Department of Clinical Infection, Microbiology and Immunology, University of Liverpool, Liverpool, United Kingdom; Haematology Department, Liverpool University Hospitals National Health Service Foundation Trust, Liverpool, United Kingdom; Roald Dahl Haemostasis and Thrombosis Centre, Liverpool University Hospitals National Health Service Foundation Trust, Liverpool, United Kingdom.
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3
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Liu Z, Li L, Zhang H, Pang X, Qiu Z, Xiang Q, Cui Y. Platelet factor 4(PF4) and its multiple roles in diseases. Blood Rev 2024; 64:101155. [PMID: 38008700 DOI: 10.1016/j.blre.2023.101155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 10/24/2023] [Accepted: 11/19/2023] [Indexed: 11/28/2023]
Abstract
Platelet factor 4 (PF4) combines with heparin to form an antigen that could produce IgG antibodies and participate in heparin-induced thrombocytopenia (HIT). PF4 has attracted wide attention due to its role in novel coronavirus vaccine-19 (COVID-9)-induced immune thrombotic thrombocytopenia (VITT) and cognitive impairments. The electrostatic interaction between PF4 and negatively charged molecules is vital in the progression of VITT, which is similar to HIT. Emerging evidence suggests its multiple roles in hematopoietic and angiogenic inhibition, platelet coagulation interference, host inflammatory response promotion, vascular inhibition, and antitumor properties. The emerging pharmacological effects of PF4 may help deepen the exploration of its mechanism, thus accelerating the development of targeted therapies. However, due to its pleiotropic properties, the development of drugs targeting PF4 is at an early stage and faces many challenges. Herein, we discussed the characteristics and biological functions of PF4, summarized PF4-mediated signaling pathways, and discussed its multiple roles in diseases to inform novel approaches for successful clinical translational research.
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Affiliation(s)
- Zhiyan Liu
- Department of Pharmacy, Peking University First Hospital, China; Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Sciences, Peking University, Beijing, China; Institute of Clinical Pharmacology, Peking University First Hospital, China.
| | - Longtu Li
- Department of Pharmacy, Peking University First Hospital, China; Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Sciences, Peking University, Beijing, China.
| | - Hanxu Zhang
- Department of Pharmacy, Peking University First Hospital, China; Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Sciences, Peking University, Beijing, China
| | - Xiaocong Pang
- Department of Pharmacy, Peking University First Hospital, China; Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Sciences, Peking University, Beijing, China; Institute of Clinical Pharmacology, Peking University First Hospital, China
| | - Zhiwei Qiu
- Department of Pharmacy, Peking University First Hospital, China; Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Sciences, Peking University, Beijing, China; Institute of Clinical Pharmacology, Peking University First Hospital, China
| | - Qian Xiang
- Department of Pharmacy, Peking University First Hospital, China; Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Sciences, Peking University, Beijing, China; Institute of Clinical Pharmacology, Peking University First Hospital, China.
| | - Yimin Cui
- Department of Pharmacy, Peking University First Hospital, China; Department of Pharmacy Administration and Clinical Pharmacy, School of Pharmaceutical Sciences, Peking University, Beijing, China; Institute of Clinical Pharmacology, Peking University First Hospital, China.
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4
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Hussein HR, Chang CY, Zheng Y, Yang CY, Li LH, Lee YT, Chen JY, Liang YC, Lin CJ, Chang YC, Geo HN, Noor SM, Kiew LV, Chen FR, Chang CC. Immune-stealth VP28-conjugated heparin nanoparticles for enhanced and reversible anticoagulation. NANOTECHNOLOGY 2024; 35:175102. [PMID: 38262054 DOI: 10.1088/1361-6528/ad21a2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 01/23/2024] [Indexed: 01/25/2024]
Abstract
Heparins are a family of sulfated linear negatively charged polysaccharides that have been widely used for their anticoagulant, antithrombotic, antitumor, anti-inflammatory, and antiviral properties. Additionally, it has been used for acute cerebral infarction relief as well as other pharmacological actions. However, heparin's self-aggregated macrocomplex may reduce blood circulation time and induce life-threatening thrombocytopenia (HIT) complicating the use of heparins. Nonetheless, the conjugation of heparin to immuno-stealth biomolecules may overcome these obstacles. An immunostealth recombinant viral capsid protein (VP28) was expressed and conjugated with heparin to form a novel nanoparticle (VP28-heparin). VP28-heparin was characterized and tested to determine its immunogenicity, anticoagulation properties, effects on total platelet count, and risk of inducing HIT in animal models. The synthesized VP28-heparin trimeric nanoparticle was non-immunogenic, possessed an average hydrodynamic size (8.81 ± 0.58 nm) optimal for the evasion renal filtration and reticuloendothelial system uptake (hence prolonging circulating half-life). Additionally, VP28-heparin did not induce mouse death or reduce blood platelet count when administered at a high dosein vivo(hence reducing HIT risks). The VP28-heparin nanoparticle also exhibited superior anticoagulation properties (2.2× higher prothrombin time) and comparable activated partial thromboplastin time, but longer anticoagulation period when compared to unfractionated heparin. The anticoagulative effects of the VP28-heparin can also be reversed using protamine sulfate. Thus, VP28-heparin may be an effective and safe heparin derivative for therapeutic use.
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Affiliation(s)
- Hussein Reda Hussein
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, 30068 Hsinchu, Taiwan
- Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Assiut branch 71524, Egypt
| | - Chia-Yu Chang
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, 30068 Hsinchu, Taiwan
| | - Yini Zheng
- Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong
| | - Chih-Yu Yang
- Institute of Clinical Medicine, School of Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan
- Division of Nephrology, Department of Medicine, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - Li-Hua Li
- Department of Pathology and laboratory medicine, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - Yi-Tzu Lee
- Department of Emergency, Taipei Veterans General Hospital, Taipei 11217, Taiwan
| | - Jun-Yi Chen
- Institute of Clinical Medicine, National Yang Ming Chiao Tung University, Taipei 11221, Taiwan
| | - Yu-Chaun Liang
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Chuan-Ju Lin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Yu-Chia Chang
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Hui Nee Geo
- Department of Pharmacology, Faculty of Medicine, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - Suzita Mohd Noor
- Department of Biomedical Science, Faculty of Medicine, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - Lik Voon Kiew
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, 30068 Hsinchu, Taiwan
- Department of Pharmacology, Faculty of Medicine, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - Fu-Rong Chen
- Department of Materials Science and Engineering, City University of Hong Kong, Hong Kong
| | - Chia-Ching Chang
- Department of Biological Science and Technology, National Yang Ming Chiao Tung University, 30068 Hsinchu, Taiwan
- Department of Electrophysics, National Yang Ming Chiao Tung University, Hsinchu 30010, Taiwan
- Center for Intelligent Drug Systems and Smart Bio-devices (IDS2B), National Yang Ming Chiao Tung University, Hsinchu 30068, Taiwan
- International College of Semiconductor Technology, National Yang Ming Chiao Tung University, 30010 Hsinchu, Taiwan
- Institute of Physics, Academia Sinica, Taipei 10529, Taiwan
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5
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Warkentin TE. Autoimmune Heparin-Induced Thrombocytopenia. J Clin Med 2023; 12:6921. [PMID: 37959386 PMCID: PMC10649402 DOI: 10.3390/jcm12216921] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 10/27/2023] [Accepted: 11/01/2023] [Indexed: 11/15/2023] Open
Abstract
Autoimmune thrombocytopenia (aHIT) is a severe subtype of heparin-induced thrombocytopenia (HIT) with atypical clinical features caused by highly pathological IgG antibodies ("aHIT antibodies") that activate platelets even in the absence of heparin. The clinical features of aHIT include: the onset or worsening of thrombocytopenia despite stopping heparin ("delayed-onset HIT"), thrombocytopenia persistence despite stopping heparin ("persisting" or "refractory HIT"), or triggered by small amounts of heparin (heparin "flush" HIT), most cases of fondaparinux-induced HIT, and patients with unusually severe HIT (e.g., multi-site or microvascular thrombosis, overt disseminated intravascular coagulation [DIC]). Special treatment approaches are required. For example, unlike classic HIT, heparin cessation does not result in de-escalation of antibody-induced hemostasis activation, and thus high-dose intravenous immunoglobulin (IVIG) may be indicated to interrupt aHIT-induced platelet activation; therapeutic plasma exchange may be required if high-dose IVIG is ineffective. Also, aHIT patients are at risk for treatment failure with (activated partial thromboplastin time [APTT]-adjusted) direct thrombin inhibitor (DTI) therapy (argatroban, bivalirudin), either because of APTT confounding (where aHIT-associated DIC and resulting APTT prolongation lead to systematic underdosing/interruption of DTI therapy) or because DTI inhibits thrombin-induced protein C activation. Most HIT laboratories do not test for aHIT antibodies, contributing to aHIT under-recognition.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular Medicine and Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada; ; Tel.: +1-(905)-527-0271 (ext. 46139)
- Service of Benign Hematology, Hamilton Health Sciences (General Site), Hamilton, ON L8L 2X2, Canada
- Transfusion Medicine, Hamilton Regional Laboratory Medicine Program, Hamilton, ON L8L 2X2, Canada
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6
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Bonnez Q, Sakai K, Vanhoorelbeke K. ADAMTS13 and Non-ADAMTS13 Biomarkers in Immune-Mediated Thrombotic Thrombocytopenic Purpura. J Clin Med 2023; 12:6169. [PMID: 37834813 PMCID: PMC10573396 DOI: 10.3390/jcm12196169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 09/20/2023] [Accepted: 09/21/2023] [Indexed: 10/15/2023] Open
Abstract
Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a rare medical emergency for which a correct and early diagnosis is essential. As a severe deficiency in A Disintegrin And Metalloproteinase with ThromboSpondin type 1 repeats, member 13 (ADAMTS13) is the underlying pathophysiology, diagnostic strategies require timely monitoring of ADAMTS13 parameters to differentiate TTP from alternative thrombotic microangiopathies (TMAs) and to guide initial patient management. Assays for conventional ADAMTS13 testing focus on the enzyme activity and presence of (inhibitory) anti-ADAMTS13 antibodies to discriminate immune-mediated TTP (iTTP) from congenital TTP and guide patient management. However, diagnosis of iTTP remains challenging when patients present borderline ADAMTS13 activity. Therefore, additional biomarkers would be helpful to support correct clinical judgment. Over the last few years, the evaluation of ADAMTS13 conformation has proven to be a valuable tool to confirm the diagnosis of acute iTTP when ADAMST13 activity is between 10 and 20%. Screening of ADAMTS13 conformation during long-term patient follow-up suggests it is a surrogate marker for undetectable antibodies. Moreover, some non-ADAMTS13 parameters gained notable interest in predicting disease outcome, proposing meticulous follow-up of iTTP patients. This review summarizes non-ADAMTS13 biomarkers for which inclusion in routine clinical testing could largely benefit differential diagnosis and follow-up of iTTP patients.
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Affiliation(s)
- Quintijn Bonnez
- Department of Chemistry, KU Leuven Campus Kulak Kortrijk, 8500 Kortrijk, Belgium
| | - Kazuya Sakai
- Department of Chemistry, KU Leuven Campus Kulak Kortrijk, 8500 Kortrijk, Belgium
- Department of Blood Transfusion Medicine, Nara Medical University, Kashihara 634-8522, Japan
| | - Karen Vanhoorelbeke
- Department of Chemistry, KU Leuven Campus Kulak Kortrijk, 8500 Kortrijk, Belgium
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7
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Huang WC, Mailer RK, Renné T. In-vivo functions and regulation of polyphosphate in the vascular system. Curr Opin Hematol 2023; 30:159-166. [PMID: 37459301 DOI: 10.1097/moh.0000000000000771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/01/2023]
Abstract
PURPOSE OF REVIEW Polyphosphate, an inorganic polymer consisting of linearly linked phosphate subunits, is ubiquitously found in living organisms. Functions and regulation of the polymer have been analyzed in plants, bacteria and yeast; however, the roles of polyphosphate in mammals are still emerging. RECENT FINDINGS In contrast to synthetic polyphosphate that has been extensively utilized in ex-vivo studies, natural polyphosphate is complexed with bivalent cations (mostly Ca 2+ ) and regardless of chain length, forms microparticles that are retained on the surface of procoagulant platelets, platelet-derived microparticles and cancer extracellular vesicles. On cell surfaces, these Ca 2+ /polyphosphate aggregates initiate the factor XII-driven contact system, triggering proinflammatory and procoagulant reactions through the kallikrein kinin system and intrinsic pathway of coagulation, respectively. Polyphosphate inhibitors interfere with thrombosis while sparing hemostasis, replicating the effect of factor XII neutralizing agents. Furthermore, polyphosphate binds to platelet factor 4, which has implications for autoimmune thrombotic diseases, such as heparin-induced thrombocytopenia (HIT) and vaccine-induced thrombotic thrombocytopenia (VITT), potentially contributing to their pathogenesis. The metabolism and organ-specific distribution of the polymer remain incompletely defined and is the topic of ongoing research. SUMMARY Polyphosphate acts as a procoagulant and proinflammatory mediator. Neutralizing polyphosphate provides well tolerated thromboprotection, mimicking the effects of factor XII deficiency.
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Affiliation(s)
- Wen-Chan Huang
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Reiner K Mailer
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas Renné
- Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Irish Centre for Vascular Biology, School of Pharmacy and Biomolecular Sciences, Royal College of Surgeons in Ireland, Dublin, Ireland
- Center for Thrombosis and Hemostasis (CTH), Johannes Gutenberg University Medical Center, Mainz, Germany
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Zhang Z, Zhou XH, Cheng ZP, Hu Y. [Research on immunological function of platelet receptor FcγRⅡA]. ZHONGHUA XUE YE XUE ZA ZHI = ZHONGHUA XUEYEXUE ZAZHI 2023; 44:609-614. [PMID: 37749049 PMCID: PMC10509618 DOI: 10.3760/cma.j.issn.0253-2727.2023.07.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Indexed: 09/27/2023]
Affiliation(s)
- Z Zhang
- Department of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - X H Zhou
- Department of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Z P Cheng
- Department of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Y Hu
- Department of Hematology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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Zhu W, Zheng Y, Yu M, Wu Y, Wei J, Zhou L, Fu G, Schneider N, Jones C, Irani M, Padmanabhan A, Aster R, Wang D, Wen R. Cloned antibodies from patients with HIT provide new clues to HIT pathogenesis. Blood 2023; 141:1060-1069. [PMID: 36493339 PMCID: PMC10023725 DOI: 10.1182/blood.2022017612] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 11/01/2022] [Accepted: 11/17/2022] [Indexed: 12/14/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a serious adverse drug reaction characterized by antibodies that recognize platelet factor 4/heparin complexes (PF4/H) and activate platelets to create a prothrombotic state. Although a high percentage of heparin-treated patients produce antibodies to PF4/H, only a subset also makes antibodies that are platelet activating (PA). A close correlation between PA antibodies and the likelihood of experiencing HIT has been demonstrated in clinical studies, but how PA (presumptively pathogenic) and nonactivating (NA) (presumptively benign) antibodies differ from each other at the molecular level is unknown. To address this issue, we cloned 7 PA and 47 NA PF4/H-binding antibodies from 6 patients with HIT and characterized their structural and functional properties. Findings showed that PA clones differed significantly from NA clones in possessing 1 of 2 heavy chain complementarity-determining region 3 (HCDR3) motifs, RX1-2R/KX1-2R/H (RKH) and YYYYY (Y5), in an unusually long complementarity-determining region 3 (≥20 residues). Mutagenic studies showed that modification of either motif in PA clones reduced or abolished their PA activity and that appropriate amino acid substitutions in HCDR3 of NA clones can cause them to become PA. Repertoire sequencing showed that the frequency of peripheral blood IgG+ B cells possessing RKH or Y5 was significantly higher in patients with HIT than in patients without HIT given heparin, indicating expansion of B cells possessing RKH or Y5 in HIT. These findings imply that antibodies possessing RKH or Y5 are relevant to HIT pathogenesis and suggest new approaches to diagnosis and treatment of this condition.
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Affiliation(s)
- Wen Zhu
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI
| | | | - Mei Yu
- Versiti Blood Research Institute, Milwaukee, WI
| | - Yaling Wu
- Versiti Blood Research Institute, Milwaukee, WI
- Biomedical Research Center of South China, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian, China
| | - Jianhui Wei
- Versiti Blood Research Institute, Milwaukee, WI
- Biomedical Research Center of South China, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian, China
| | - Lu Zhou
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI
| | - Guoping Fu
- Versiti Blood Research Institute, Milwaukee, WI
| | | | | | - Mehraboon Irani
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI
| | - Anand Padmanabhan
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Laboratory Medicine & Pathology, Mayo Clinic, Rochester, MN
| | - Richard Aster
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI
| | - Demin Wang
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI
| | - Renren Wen
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI
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10
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Venier LM, Clerici B, Bissola AL, Modi D, Jevtic SD, Radford M, Mahamad S, Nazy I, Arnold DM. Unique features of vaccine-induced immune thrombotic thrombocytopenia; a new anti-platelet factor 4 antibody-mediated disorder. Int J Hematol 2023; 117:341-348. [PMID: 36574172 PMCID: PMC9793819 DOI: 10.1007/s12185-022-03516-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/02/2022] [Accepted: 12/12/2022] [Indexed: 12/29/2022]
Abstract
Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a highly prothrombotic disorder caused by anti-PF4 antibodies that activate platelets and neutrophils, leading to thrombosis. Heparin-induced thrombocytopenia (HIT) is a related anti-PF4 mediated disorder, with similar pathophysiology and clinical manifestations but different triggers (i.e., heparin vs adenoviral vector vaccine). Clinically, both HIT and VITT typically present with thrombocytopenia and thrombosis, although the risk of thrombosis is significantly higher in VITT, and the thromboses occur in unusual anatomical sites (e.g., cerebral venous sinus thrombosis and hepatic vein thrombosis). The diagnostic accuracy of available laboratory testing differs between HIT and VITT; for VITT, ELISAs have better specificity compared to HIT and platelet activation assays require the addition of PF4. Treatment of VITT and HIT is anticoagulation non-heparin anticoagulants; however, heparin may be considered for VITT if no other option is available.
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Affiliation(s)
- Laura M. Venier
- Faculty of Health Sciences, McMaster University, Hamilton, ON Canada
| | - Bianca Clerici
- Divisione di Medicina Generale II, ASST Santi Paolo e Carlo, Dipartimento di Scienze della Salute, Università degli Studi di Milano, Milan, Italy ,McMaster Centre for Transfusion Research, McMaster University, 1280 Main Street West, Room HSC 3H50, Hamilton, ON L8S 4K1 Canada
| | - Anna-Lise Bissola
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON Canada ,Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON Canada
| | - Dimpy Modi
- McMaster Centre for Transfusion Research, McMaster University, 1280 Main Street West, Room HSC 3H50, Hamilton, ON L8S 4K1 Canada
| | - Stefan D. Jevtic
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON Canada
| | - Michael Radford
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON Canada
| | - Syed Mahamad
- McMaster Centre for Transfusion Research, McMaster University, 1280 Main Street West, Room HSC 3H50, Hamilton, ON L8S 4K1 Canada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON Canada ,McMaster Centre for Transfusion Research, McMaster University, 1280 Main Street West, Room HSC 3H50, Hamilton, ON L8S 4K1 Canada
| | - Donald M. Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON Canada ,McMaster Centre for Transfusion Research, McMaster University, 1280 Main Street West, Room HSC 3H50, Hamilton, ON L8S 4K1 Canada
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11
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Jevtic SD, Arnold DM, Modi D, Ivetic N, Bissola AL, Nazy I. Vaccine-induced immune thrombotic thrombocytopenia: Updates in pathobiology and diagnosis. Front Cardiovasc Med 2022; 9:1040196. [PMID: 36352844 PMCID: PMC9637757 DOI: 10.3389/fcvm.2022.1040196] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 10/04/2022] [Indexed: 11/12/2023] Open
Abstract
Coronavirus disease 2019 (COVID-19) is a viral respiratory infection caused by the severe acute respiratory syndrome virus (SARS-CoV-2). Vaccines that protect against SARS-CoV-2 infection have been widely employed to reduce the incidence of symptomatic and severe disease. However, adenovirus-based SARS-CoV-2 vaccines can cause a rare, thrombotic disorder termed vaccine-induced immune thrombotic thrombocytopenia (VITT). VITT often develops in the first 5 to 30 days following vaccination and is characterized by thrombocytopenia and thrombosis in unusual locations (e.g., cerebral venous sinus thrombosis). The diagnosis is confirmed by testing for anti-PF4 antibodies, as these antibodies are capable of platelet activation without any cofactor. It can be clinically challenging to differentiate VITT from a similar disorder called heparin-induced thrombocytopenia (HIT), since heparin is commonly used in hospitalized patients. VITT and HIT have similar pathobiology and clinical manifestations but important differences in testing including the need for PF4-enhanced functional assays and the poor reliability of rapid immunoassays for the detection of anti-platelet factor 4 (PF4) antibodies. In this review we summarize the epidemiology of VITT; highlight similarities and differences between HIT and VITT; and provide an update on the clinical diagnosis of VITT.
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Affiliation(s)
- Stefan D. Jevtic
- 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
- McMaster Centre for Transfusion Research, McMaster University, Hamilton, ON, Canada
- Canadian Blood Services, Hamilton, ON, Canada
| | - Dimpy Modi
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, McMaster University, Hamilton, ON, Canada
| | - Nikola Ivetic
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
| | - Anna-Lise Bissola
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, McMaster University, Hamilton, ON, Canada
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12
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Chen LY, Khan N, Lindenbauer A, Nguyen TH. When Will Fondaparinux Induce Thrombocytopenia? Bioconjug Chem 2022; 33:1574-1583. [PMID: 35878320 PMCID: PMC9390334 DOI: 10.1021/acs.bioconjchem.2c00316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The pentasaccharide Fondaparinux, a synthetic selective factor Xa inhibitor, is one of the safest anticoagulants in the heparin family that is recommended as an alternative drug for patients with hypersensitivity to other drugs such as heparin-induced thrombocytopenia (HIT). However, some observations of Fondaparinux-induced thrombocytopenia (FIT) have been reported while others claimed that FIT does not occur in patients with fondaparinux therapy, indicating that the mechanism of FIT remains controversial. Here, we utilized different methodologies including dynamic light scattering, immunosorbent and platelet aggregation assays, confocal laser scanning microscopy, and flow cytometry to gain insights into FIT. We found that at a certain concentration, Fondaparinux formed sufficient large and stable complexes with PF4 that facilitated binding of the HIT-like monoclonal KKO antibody and enhanced platelet aggregation and activation. We proposed a model to describe the role of Fondaparinux concentration in the formation of complexes with platelet factor 4 and how it promotes the binding of KKO. Our results clarify controversial observations of FIT in patients as each contains a dissimilar PF4:Fondaparinux concentration ratio.
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Affiliation(s)
- Li-Yu Chen
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany.,Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, 07745 Jena, Germany
| | - Nida Khan
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany.,Faculty of Mathematics and Natural Sciences, Technische Universität Ilmenau, 98694 Ilmenau, Germany
| | - Annerose Lindenbauer
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany
| | - Thi-Huong Nguyen
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany.,Faculty of Mathematics and Natural Sciences, Technische Universität Ilmenau, 98694 Ilmenau, Germany
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13
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The interaction between anti-PF4 antibodies and anticoagulants in vaccine-induced thrombotic thrombocytopenia. Blood 2022; 139:3430-3438. [PMID: 35679071 PMCID: PMC8949646 DOI: 10.1182/blood.2021013839] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 03/18/2022] [Indexed: 02/08/2023] Open
Abstract
Life-threatening thrombotic events at unusual sites have been reported after vector-based vaccinations against severe acute respiratory syndrome coronavirus 2. This phenomenon is now termed vaccine-induced immune thrombotic thrombocytopenia (VITT). The pathophysiology of VITT is similar to that of heparin-induced thrombocytopenia (HIT) and is associated with platelet-activating antibodies (Abs) against platelet factor 4 (PF4). Therefore, current guidelines suggest nonheparin anticoagulants to treat VITT patients. In this study, we investigated the interactions of heparin, danaparoid, fondaparinux, and argatroban with VITT-Ab/PF4 complexes using an ex vivo model for thrombus formation as well as in vitro assays to analyze Ab binding and platelet activation. We found that immunoglobulin Gs (IgGs) from VITT patients induce increased adherent platelets/thrombus formation in comparison with IgGs from healthy controls. In this ex vivo flow-based model, the procoagulant activity of VITT IgGs was effectively inhibited with danaparoid and argatroban but also by heparin. Interestingly, heparin and danaparoid not only inhibited IgG binding to PF4 but were also able to effectively dissociate the preformed PF4/IgG complexes. Fondaparinux reduced the in vitro generation of procoagulant platelets and thrombus formation; however, it did not affect platelet aggregation. In contrast, argatroban showed no effect on procoagulant platelets and aggregation but significantly inhibited VITT-mediated thrombus formation. Taken together, our data indicate that negatively charged anticoagulants can disrupt VITT-Ab/PF4 interactions, which might serve as an approach to reduce Ab-mediated complications in VITT. Our results should be confirmed, however, in a clinical setting before a recommendation regarding the selection of anticoagulants in VITT patients could be made.
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14
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Miller E, Norwood C, Giles JB, Huddart R, Karnes JH, Whirl-Carrillo M, Klein TE. PharmGKB summary: heparin-induced thrombocytopenia pathway, adverse drug reaction. Pharmacogenet Genomics 2022; 32:117-124. [PMID: 35102073 PMCID: PMC8988468 DOI: 10.1097/fpc.0000000000000465] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Elise Miller
- Department of Pharmacy Practice and Science, University of Arizona College of Pharmacy, Tucson, Arizona
| | - Charles Norwood
- Department of Pharmacy Practice and Science, University of Arizona College of Pharmacy, Tucson, Arizona
| | - Jason B. Giles
- Department of Pharmacy Practice and Science, University of Arizona College of Pharmacy, Tucson, Arizona
| | - Rachel Huddart
- Department of Biomedical Data Science, Stanford University, Stanford, CA
| | - Jason H. Karnes
- Department of Pharmacy Practice and Science, University of Arizona College of Pharmacy, Tucson, Arizona
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN
| | | | - Teri E. Klein
- Department of Biomedical Data Science, Stanford University, Stanford, CA
- Department of Biomedical Informatics Research, Stanford University, Stanford, CA
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15
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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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16
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Khan NZ, Chen LY, Lindenbauer A, Pliquett U, Rothe H, Nguyen TH. Label-Free Detection and Characterization of Heparin-Induced Thrombocytopenia (HIT)-like Antibodies. ACS OMEGA 2021; 6:25926-25939. [PMID: 34660955 PMCID: PMC8515375 DOI: 10.1021/acsomega.1c02496] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 09/16/2021] [Indexed: 05/04/2023]
Abstract
Heparin-induced thrombocytopenia (HIT) antibodies (Abs) can mediate and activate blood cells, forming blood clots. To detect HIT Abs, immunological assays with high sensitivity (≥95%) and fast response are widely used, but only about 50% of these tests are accurate as non-HIT Abs also bind to the same antigens. We aim to develop biosensor-based electrical detection to better differentiate HIT-like from non-HIT-like Abs. As a proof of principle, we tested with two types of commercially available monoclonal Abs including KKO (inducing HIT) and RTO (noninducing HIT). Platelet factor 4/Heparin antigens were immobilized on gold electrodes, and binding of antibodies on the chips was detected based on the change in the charge transfer resistance (R ct). Binding of KKO on sensors yielded a significantly lower charge transfer resistance than that of RTO. Bound antibodies and their binding characteristics on the sensors were confirmed and characterized by complementary techniques. Analysis of thermal kinetics showed that RTO bonds are more stable than those of KKO, whereas KKO exhibited a higher negative ζ potential than RTO. These different characteristics made it possible to electrically differentiate these two types of antibodies. Our study opens a new avenue for the development of sensors for better detection of pathogenic Abs in HIT patients.
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Affiliation(s)
- Nida Zaman Khan
- Institute
for Bioprocessing and Analytical Measurement Techniques (iba), 37308 Heiligenstadt, Germany
- Institute
for Chemistry and Biotechnology, Faculty of Mathematics and Natural
Sciences, Technische Universität
Ilmenau, 98694 Ilmenau, Germany
| | - Li-Yu Chen
- Institute
for Bioprocessing and Analytical Measurement Techniques (iba), 37308 Heiligenstadt, Germany
- Institute
of Microbiology, Friedrich Schiller University, 07745 Jena, Germany
| | - Annerose Lindenbauer
- Institute
for Bioprocessing and Analytical Measurement Techniques (iba), 37308 Heiligenstadt, Germany
| | - Uwe Pliquett
- Institute
for Bioprocessing and Analytical Measurement Techniques (iba), 37308 Heiligenstadt, Germany
| | - Holger Rothe
- Institute
for Bioprocessing and Analytical Measurement Techniques (iba), 37308 Heiligenstadt, Germany
| | - Thi-Huong Nguyen
- Institute
for Bioprocessing and Analytical Measurement Techniques (iba), 37308 Heiligenstadt, Germany
- Institute
for Chemistry and Biotechnology, Faculty of Mathematics and Natural
Sciences, Technische Universität
Ilmenau, 98694 Ilmenau, Germany
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17
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Abstract
Anticoagulant and antiplatelet drugs target a specific portion of the coagulation cascade or the platelet activation and aggregation pathway. The primary toxicity associated with these agents is hemorrhage. Understanding the pharmacology of these drugs allows the treating clinician to choose the correct antidotal therapy. Reversal agents exist for some of these drugs; however, not all have proven patient-centered outcomes. The anticoagulants covered in this review are vitamin K antagonists, heparins, fondaparinux, hirudin derivatives, argatroban, oral factor Xa antagonists, and dabigatran. The antiplatelet agents reviewed are aspirin, adenosine diphosphate antagonists, dipyridamole, and glycoprotein IIb/IIIa antagonists. Additional notable toxicities are also reviewed.
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Affiliation(s)
- David B Liss
- Department of Emergency Medicine, Division of Medical Toxicology, Washington University in St. Louis, 660 South Euclid Avenue, CB 8072, St Louis, MO 63110, USA.
| | - Michael E Mullins
- Department of Emergency Medicine, Division of Medical Toxicology, Washington University in St. Louis, 660 South Euclid Avenue, CB 8072, St Louis, MO 63110, USA
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18
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Chen LY, Apte G, Lindenbauer A, Frant M, Nguyen TH. Effect of HIT Components on the Development of Breast Cancer Cells. Life (Basel) 2021; 11:life11080832. [PMID: 34440575 PMCID: PMC8399975 DOI: 10.3390/life11080832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 07/30/2021] [Accepted: 08/05/2021] [Indexed: 12/12/2022] Open
Abstract
Cancer cells circulating in blood vessels activate platelets, forming a cancer cell encircling platelet cloak which facilitates cancer metastasis. Heparin (H) is frequently used as an anticoagulant in cancer patients but up to 5% of patients have a side effect, heparin-induced thrombocytopenia (HIT) that can be life-threatening. HIT is developed due to a complex interaction among multiple components including heparin, platelet factor 4 (PF4), HIT antibodies, and platelets. However, available information regarding the effect of HIT components on cancers is limited. Here, we investigated the effect of these materials on the mechanical property of breast cancer cells using atomic force microscopy (AFM) while cell spreading was quantified by confocal laser scanning microscopy (CLSM), and cell proliferation rate was determined. Over time, we found a clear effect of each component on cell elasticity and cell spreading. In the absence of platelets, HIT antibodies inhibited cell proliferation but they promoted cell proliferation in the presence of platelets. Our results indicate that HIT complexes influenced the development of breast cancer cells.
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Affiliation(s)
- Li-Yu Chen
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany; (L.-Y.C.); (G.A.); (A.L.); (M.F.)
- Department of Infection Biology, Leibniz Institute for Natural Product Research and Infection Biology, 07745 Jena, Germany
| | - Gurunath Apte
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany; (L.-Y.C.); (G.A.); (A.L.); (M.F.)
- Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Annerose Lindenbauer
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany; (L.-Y.C.); (G.A.); (A.L.); (M.F.)
| | - Marion Frant
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany; (L.-Y.C.); (G.A.); (A.L.); (M.F.)
| | - Thi-Huong Nguyen
- Institute for Bioprocessing and Analytical Measurement Techniques, 37308 Heiligenstadt, Germany; (L.-Y.C.); (G.A.); (A.L.); (M.F.)
- Faculty of Mathematics and Natural Sciences, Technische Universität Ilmenau, 98694 Ilmenau, Germany
- Correspondence:
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19
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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: 62] [Impact Index Per Article: 20.7] [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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20
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Chong BH. Evolving concepts of pathogenesis of heparin-induced thrombocytopenia: Diagnostic and therapeutic implications. Int J Lab Hematol 2021; 42 Suppl 1:25-32. [PMID: 32543064 DOI: 10.1111/ijlh.13223] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Revised: 04/08/2020] [Accepted: 04/10/2020] [Indexed: 01/09/2023]
Abstract
Heparin-induced thrombocytopenia (HIT) is an immune reaction to heparin. It often causes severe thrombosis which may lead to limb gangrene and thrombosis-associated death. The concept of its pathogenesis has been evolving during the past five decades. Initially, HIT was thought to be caused by disseminated intravascular coagulation. Later it became clear that HIT was mediated by an immune mechanism whereby an IgG antibody induced platelet aggregation, release of procoagulant materials and consequently thrombus formation. The antigen comprises Platelet Factor 4 (PF4) and heparin which have a tendency to form ultralarge complexes. The HIT immune response has atypical features. IgG antibody appears early without IgM precedence and lasts transiently. One explanation is that there is prior priming by bacterial infection. Another unique characteristic is that it is processed as if it is a particulate antigen involving complement activation and B cells. Antigen-presenting cells/monocytes are also involved but the role of T cells is controversial. Recent advances have provided new insights into the underlying mechanisms of HIT-related thrombosis. Previously, platelets were believed to play a central role; their activation and consequently the induction of blood coagulation was the basis of the hypercoagulability in HIT. More recently, several studies have provided clear evidence that neutrophil and NETosis, monocytes and endothelial cells contribute significantly to the thrombosis in HIT. These new insights may result in development of better diagnostic laboratory assays and more effective treatments for HIT.
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Affiliation(s)
- Beng H Chong
- Heamatology Department, New South Wales Health Pathology, Kogarah and Sutherland Campuses, Sydney, NSW, Australia.,Heamatolgy Department, St George and Sutherland Hospitals, Sydney, NSW, Australia.,St George Clinical School, University of New South Wales, Sydney, NSW, Australia
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21
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Vayne C, Guéry EA, Rollin J, Baglo T, Petermann R, Gruel Y. Pathophysiology and Diagnosis of Drug-Induced Immune Thrombocytopenia. J Clin Med 2020; 9:E2212. [PMID: 32668640 PMCID: PMC7408966 DOI: 10.3390/jcm9072212] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 07/09/2020] [Accepted: 07/10/2020] [Indexed: 12/12/2022] Open
Abstract
Drug-induced immune thrombocytopenia (DITP) is a life-threatening clinical syndrome that is under-recognized and difficult to diagnose. Many drugs can cause immune-mediated thrombocytopenia, but the most commonly implicated are abciximab, carbamazepine, ceftriaxone, eptifibatide, heparin, ibuprofen, mirtazapine, oxaliplatin, penicillin, quinine, quinidine, rifampicin, suramin, tirofiban, trimethoprim-sulfamethoxazole, and vancomycin. Several different mechanisms have been identified in typical DITP, which is most commonly characterized by severe thrombocytopenia due to clearance and/or destruction of platelets sensitized by a drug-dependent antibody. Patients with typical DITP usually bleed when symptomatic, and biological confirmation of the diagnosis is often difficult because detection of drug-dependent antibodies (DDabs) in the patient's serum or plasma is frequently not possible. This is in contrast to heparin-induced thrombocytopenia (HIT), which is a particular DITP caused in most cases by heparin-dependent antibodies specific for platelet factor 4, which can strongly activate platelets in vitro and in vivo, explaining why affected patients usually have thrombotic complications but do not bleed. In addition, laboratory tests are readily available to diagnose HIT, unlike the methods used to detect DDabs associated with other DITP that are mostly reserved for laboratories specialized in platelet immunology.
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Affiliation(s)
- Caroline Vayne
- EA 7501-Groupe Innovation et Ciblage Cellulaire (GICC), Université François Rabelais, CEDEX 01, 37032 Tours, France; (C.V.); (J.R.)
- Laboratoire d’Hématologie-Hémostase, Hôpital Trousseau, CHRU Tours, CEDEX 09, 37044 Tours, France; (E.-A.G.); (T.B.)
| | - Eve-Anne Guéry
- Laboratoire d’Hématologie-Hémostase, Hôpital Trousseau, CHRU Tours, CEDEX 09, 37044 Tours, France; (E.-A.G.); (T.B.)
| | - Jérôme Rollin
- EA 7501-Groupe Innovation et Ciblage Cellulaire (GICC), Université François Rabelais, CEDEX 01, 37032 Tours, France; (C.V.); (J.R.)
- Laboratoire d’Hématologie-Hémostase, Hôpital Trousseau, CHRU Tours, CEDEX 09, 37044 Tours, France; (E.-A.G.); (T.B.)
| | - Tatiana Baglo
- Laboratoire d’Hématologie-Hémostase, Hôpital Trousseau, CHRU Tours, CEDEX 09, 37044 Tours, France; (E.-A.G.); (T.B.)
- Laboratoire d’Hématologie, CNHU de Cotonou, Cotonou 01 BP 386, Benin
| | - Rachel Petermann
- Département d’Immunologie plaquettaire, Institut National de la Transfusion Sanguine (INTS), 75015 Paris, France;
- Equipe ETRES (Ethics, Research, Translations), Centre de Recherche des Cordeliers, UMRS 1138, INSERM, Sorbonne Université, Université de Paris, 75006 Paris, France
| | - Yves Gruel
- EA 7501-Groupe Innovation et Ciblage Cellulaire (GICC), Université François Rabelais, CEDEX 01, 37032 Tours, France; (C.V.); (J.R.)
- Laboratoire d’Hématologie-Hémostase, Hôpital Trousseau, CHRU Tours, CEDEX 09, 37044 Tours, France; (E.-A.G.); (T.B.)
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22
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Singh N, Singh Lubana S, Tsai HM. Myocardial Infarction with Limb Arterial and Venous Thrombosis in a Patient with Enoxaparin-Induced Thrombocytopenia. AMERICAN JOURNAL OF CASE REPORTS 2020; 21:e922498. [PMID: 32469847 PMCID: PMC7286187 DOI: 10.12659/ajcr.922498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Patient: Female, 67-year-old Final Diagnosis: Enoxaparin induced thrombocytopenia with life threatening thrombosis Symptoms: Chest discomfort Medication:— Clinical Procedure: — Specialty: Hematology
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Affiliation(s)
- Navdeep Singh
- Department of Medicine, Division of Hospice and Palliative Care, North Shore University Hospital, Manhasset, NY, USA
| | - Sandeep Singh Lubana
- Department of Medicine, Division of Hematology and Oncology, State University New York (SUNY) Downstate Medical Center, Brooklyn, NY, USA
| | - Han-Mou Tsai
- Department of Medicine, Division of Hematology and Oncology, State University New York (SUNY) Downstate Medical Center, Brooklyn, NY, USA
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23
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Nguyen TH, Xu Y, Brandt S, Mandelkow M, Raschke R, Strobel U, Delcea M, Zhou W, Liu J, Greinacher A. Characterization of the interaction between platelet factor 4 and homogeneous synthetic low molecular weight heparins. J Thromb Haemost 2020; 18:390-398. [PMID: 31573759 PMCID: PMC7236814 DOI: 10.1111/jth.14657] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 09/25/2019] [Indexed: 01/03/2023]
Abstract
BACKGROUND Heparins are usually produced from animal tissues. It is now possible to synthesize heparins. This provides the abilities to overcome shortages of heparin, to optimize biological effects, and to reduce adverse drug effects. Heparins interact with platelet factor 4 (PF4), which can induce an immune response causing thrombocytopenia. This side effect is called heparin-induced thrombocytopenia (HIT). We characterized the interaction of PF4 and HIT antibodies with oligosaccharides of 6-, 8-, 10-, and 12-mer size and a hypersulfated 12-mer (S12-mer). METHODS We utilized multiple methodologies including isothermal calorimetry, circular dichroism spectroscopy, single molecule force spectroscopy (SMFS), enzyme immunosorbent assay (EIA), and platelet aggregation test to characterize the interaction of synthetic heparin analogs with PF4 and anti-PF4/heparin antibodies. RESULTS The synthetic heparin-like compounds display stronger binding characteristics to PF4 than animal-derived heparins of corresponding lengths. Upon complexation with PF4, 6-mer and S12-mer heparins showed much lower enthalpy, induced less conformational changes in PF4, and interacted with weaker forces than 8-, 10-, and 12-mer heparins. Anti-PF4/heparin antibodies bind more weakly to complexes formed between PF4 and heparins ≤ 8-mer than with complexes formed between PF4 and heparins ≥ 10-mer. Addition of one sulfate group to the 12-mer resulted in a S12-mer, which showed substantial changes in its binding characteristics to PF4. CONCLUSIONS We provide a template for characterizing interactions of newly developed heparin-based anticoagulant drugs with proteins, especially PF4 and the resulting potential antigenicity.
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Affiliation(s)
- Thi-Huong Nguyen
- institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
- Institute for Bioprocessing and Analytical Measurement Techniques, Heiligenstadt, Germany
- ZIK HIKE—Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University Greifswald, Greifswald, Germany
| | - Yongmei Xu
- Division of Chemical Biology and Medicinal Chemistry, School of Pharmacy, University of North Carolina, Eshelman, Chapel Hill, NC, USA
| | - Sven Brandt
- ZIK HIKE—Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University Greifswald, Greifswald, Germany
| | - Martin Mandelkow
- ZIK HIKE—Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University Greifswald, Greifswald, Germany
| | - Ricarda Raschke
- institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Ulrike Strobel
- institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Mihaela Delcea
- ZIK HIKE—Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University Greifswald, Greifswald, Germany
- Division of Chemical Biology and Medicinal Chemistry, School of Pharmacy, University of North Carolina, Eshelman, Chapel Hill, NC, USA
| | - Wen Zhou
- Institute of Biochemistry, University Greifswald, Greifswald, Germany
| | - Jian Liu
- Institute of Biochemistry, University Greifswald, Greifswald, Germany
| | - Andreas Greinacher
- institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
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The impact of physiological stress conditions on protein structure and trypsin inhibition of serine protease inhibitor Kazal type 1 (SPINK1) and its N34S variant. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1868:140281. [PMID: 31525466 PMCID: PMC6905150 DOI: 10.1016/j.bbapap.2019.140281] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 08/27/2019] [Accepted: 09/11/2019] [Indexed: 12/14/2022]
Abstract
One of the most common mutations in the serine protease inhibitor Kazal type 1 (SPINK1) gene is the N34S variant which is strongly associated with chronic pancreatitis. Although it is assumed that N34S mutation constitutes a high-risk factor, the underlying pathologic mechanism is still unknown. In the present study, we investigated the impact of physiological stress factors on SPINK1 protein structure and trypsin inhibitor function using biophysical methods. Our circular dichroism spectroscopy data revealed differences in the secondary structure of SPINK1 and N34S mutant suggesting protein structural changes induced by the mutation as an impairment that could be disease-relevant. We further confirmed that both SPINK1 (KD of 0.15 ± 0.06 nM) and its N34S variant (KD of 0.08 ± 0.02 nM) have similar binding affinity and inhibitory effect towards trypsin as shown by surface plasmon resonance and trypsin inhibition assay studies, respectively. We found that stress conditions such as altered ion concentrations (i.e. potassium, calcium), temperature shifts, as well as environmental pH lead to insignificant differences in trypsin inhibition between SPINK1 and N34S mutant. However, we have shown that the environmental pH induces structural changes in both SPINK1 constructs in a different manner. Our findings suggest protein structural changes in the N34S variant as an impairment of SPINK1 and environmental pH shift as a trigger that could play a role in disease progression of pancreatitis.
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25
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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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26
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Buchholz I, Nestler P, Köppen S, Delcea M. Lysine residues control the conformational dynamics of beta 2-glycoprotein I. Phys Chem Chem Phys 2018; 20:26819-26829. [PMID: 30176030 DOI: 10.1039/c8cp03234c] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
One of the major problems in the study of the dynamics of proteins is the visualization of changing conformations that are important for processes ranging from enzyme catalysis to signaling. A protein exhibiting conformational dynamics is the soluble blood protein beta 2-glycoprotein I (beta2GPI), which exists in two conformations: the closed (circular) form and the open (linear) form. It is hypothesized that an increased proportion of the open conformation leads to the autoimmune disease antiphospholipid syndrome (APS). A characteristic feature of beta2GPI is the high content of lysine residues. However, the potential role of lysine in the conformational dynamics of beta2GPI has been poorly investigated. Here, we report on a strategy to permanently open up the closed protein conformation by chemical acetylation of lysine residues using acetic acid N-hydroxysuccinimide ester (NHS-Ac). Specific and complete acetylation was demonstrated by the quantification of primary amino groups with fluoraldehyde o-phthalaldehyde (OPA) reagent, as well as western blot analysis with an anti-acetylated lysine antibody. Our results demonstrate that acetylated beta2GPI preserves its secondary and tertiary structures, as shown by circular dichroism spectroscopy. We found that after lysine acetylation, the majority of proteins are in the open conformation as revealed by atomic force microscopy high-resolution images. Using this strategy, we proved that the electrostatic interaction of lysine residues plays a major role in stabilizing the beta2GPI closed conformation, as confirmed by lysine charge distribution calculations. We foresee that our approach will be applied to other lysine-rich proteins (e.g. histones) undergoing conformational transitions. For instance, conformational dynamics can be triggered by environmental conditions (e.g. pH, ion concentration, post-translational modifications, and binding of ligands). Therefore, our study may be relevant for investigating the equilibrium of protein conformations causing diseases.
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Affiliation(s)
- Ina Buchholz
- Institute of Biochemistry, Ernst-Moritz-Arndt University Greifswald, 17489 Greifswald, Germany.
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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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Jindal V, Singh A, Siddiqui AD, Leb L. The Appropriateness of Testing Platelet Factor 4/Heparin Antibody in Patients Suspected of Heparin-induced Thrombocytopenia. Cureus 2018; 10:e3532. [PMID: 30648066 PMCID: PMC6318092 DOI: 10.7759/cureus.3532] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is an adverse reaction to the administration of heparin due to the activation of the platelets by the immunoglobulin G (IgG) antibody-platelet factor 4 (PF4)/heparin immune complex. Since the clinical outcome is uncertain (as it could be associated with significant morbidity and sometimes death), an early diagnosis and appropriate treatment are necessary. The 4Ts pretest clinical scoring system and testing for all anti-PF4/heparin antibodies can markedly improve the diagnosis and prompt adequate treatment. Our study was undertaken to retrospectively evaluate the appropriateness of ordering the PF4 enzyme-linked immunosorbent assay (ELISA) test by using the 4Ts scoring system in a tertiary institution. We examined a database of 118 patients who had the PF4 ELISA test and calculated their 4Ts scores retrospectively. A total of 107 patients were evaluated; 95 patients (88.79%) had a negative PF4 ELISA assay and 12 patients tested positive (11.21%). Only one patient tested weakly positive in the low probability group (negative predictive value 98%). In the intermediate group, six patients were strongly positive (optical density (OD) > 1.0). In this latter group, further confirmatory testing using serotonin release assays (SRAs) could have been done. We also evaluated the setting where the tests were performed and found that the majority of patients (63.55%) were tested in the intensive care unit (ICU) where thrombocytopenia is multifactorial. We concluded that the large majority of patients were not appropriately evaluated prior to testing, which incurred unnecessary expense and patient distress. For the proper identification of patients suspected of HIT who should undergo PF4/heparin antibody testing, further education of the ordering physicians is recommended.
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Affiliation(s)
- Vishal Jindal
- Internal Medicine, St. Vincent Hospital, Worcester, USA
| | - Aditi Singh
- Internal Medicine, St. Vincent Hospital, Worcester, USA
| | | | - Laszlo Leb
- Hematology and Oncology, St. Vincent Hospital, Worcester, 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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Palankar R, Kohler TP, Krauel K, Wesche J, Hammerschmidt S, Greinacher A. Platelets kill bacteria by bridging innate and adaptive immunity via platelet factor 4 and FcγRIIA. J Thromb Haemost 2018; 16:1187-1197. [PMID: 29350833 DOI: 10.1111/jth.13955] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Indexed: 12/15/2022]
Abstract
Essentials Human platelets specifically interact with IgG opsonized bacteria through FcγRIIA. Platelet factor 4 (PF4) binds to polyanions (P) and undergoes a conformational change. Anti-PF4/P IgG opsonizes PF4-coated Gram-positive and Gram-negative bacteria. Platelets specifically kill E.coli opsonized with PF4 and human anti-PF4/P IgG. SUMMARY Background Activated platelets release the chemokine platelet factor 4 (PF4) stored in their granules. PF4 binds to polyanions (P) on bacteria, undergoes a conformational change and exposes neoepitopes. These neoepitopes induce production of anti-PF4/P antibodies. As PF4 binds to a variety of bacteria, anti-PF4/P IgG can bind and opsonize several bacterial species. Objective Here we investigated whether platelets are able to kill bacteria directly after recognizing anti-PF4/P IgG opsonized bacteria in the presence of PF4 via their FcγRIIA. Methods Using platelet-bacteria suspension co-culture experiments and micropatterns with immobilized viable bacteria, in combination with pharmacological inhibitors and human anti- PF4/P IgG we analyzed the role of platelet-mediated killing of bacteria. Results In the presence of PF4, human anti-PF4/P IgG and platelets, E. coli killing (> 50%) with colony forming units (CFU mL-1 ) 0.71 × 104 ± 0.19 was observed compared with controls incubated only with anti-PF4/P IgG (CFU mL-1 3.4 × 104 ± 0.38). Blocking of platelet FcγRIIA using mAb IV.3 (CFU mL-1 2.5 × 104 ± 0.45), or integrin αIIbβ3 (CFU mL-1 2.26 × 104 ± 0.31), or disruption of cytoskeletal functions (CFU mL-1 2.7 × 104 ± 0.4) markedly reduced E. coli killing by this mechanism. Our observation of E. coli killing by platelets on micropatterned arrays is compatible with the model that platelets kill bacteria by covering them, actively concentrating them into the area under their granulomere and then releasing antimicrobial substances of platelet α-granules site directed towards bacteria. Conclusion These findings collectively indicate that by bridging of innate and adaptive immune mechanisms, platelets and anti-PF4/polyanion antibodies cooperate in an antibacterial host response.
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Affiliation(s)
- R Palankar
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - T P Kohler
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - K Krauel
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - J Wesche
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
| | - S Hammerschmidt
- Department of Molecular Genetics and Infection Biology, Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - A Greinacher
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
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Bui VC, Nguyen TH. The Role of Single-Molecule Force Spectroscopy in Unraveling Typical and Autoimmune Heparin-induced Thrombocytopenia. Int J Mol Sci 2018; 19:E1054. [PMID: 29614814 PMCID: PMC5979551 DOI: 10.3390/ijms19041054] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 03/26/2018] [Accepted: 03/31/2018] [Indexed: 02/07/2023] Open
Abstract
For the last two decades, heparins have been widely used as anticoagulants. Besides numerous advantages, up to 5% patients with heparin administration suffer from a major adverse drug effect known as heparin-induced thrombocytopenia (HIT). This typical HIT can result in deep vein thrombosis, pulmonary embolism, occlusion of a limb artery, acute myocardial infarct, stroke, and a systemic reaction or skin necrosis. The basis of HIT may lead to clinical insights. Recent studies using single-molecule force spectroscopy (SMFS)-based atomic force microscopy revealed detailed binding mechanisms of the interactions between platelet factor 4 (PF4) and heparins of different lengths in typical HIT. Especially, SMFS results allowed identifying a new mechanism of the autoimmune HIT caused by a subset of human-derived antibodies in patients without heparin exposure. The findings proved that not only heparin but also a subset of antibodies induce thrombocytopenia. In this review, the role of SMFS in unraveling a major adverse drug effect and insights into molecular mechanisms inducing thrombocytopenia by both heparins and antibodies will be discussed.
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Affiliation(s)
- Van-Chien Bui
- Institute for Immunology and Transfusion Medicine, University Medicine of Greifswald, 17475 Greifswald, Germany.
| | - Thi-Huong Nguyen
- Institute for Immunology and Transfusion Medicine, University Medicine of Greifswald, 17475 Greifswald, Germany.
- ZIK HIKE-Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular, 17489 Greifswald, Germany.
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Roose E, Schelpe AS, Joly BS, Peetermans M, Verhamme P, Voorberg J, Greinacher A, Deckmyn H, De Meyer SF, Coppo P, Veyradier A, Vanhoorelbeke K. An open conformation of ADAMTS-13 is a hallmark of acute acquired thrombotic thrombocytopenic purpura. J Thromb Haemost 2018; 16:378-388. [PMID: 29222940 DOI: 10.1111/jth.13922] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Indexed: 12/20/2022]
Abstract
Essentials Conformational changes in ADAMTS-13 are part of its mode-of-action. The murine anti-ADAMTS-13 antibody 1C4 discriminates between folded and open ADAMTS-13. ADAMTS-13 conformation is open in acute acquired thrombotic thrombocytopenic purpura (TTP). Our study forms an important basis to fully elucidate the pathophysiology of TTP. SUMMARY Background Acquired thrombotic thrombocytopenic purpura (aTTP) is an autoimmune disorder characterized by absent ADAMTS-13 activity and the presence of anti-ADAMTS-13 autoantibodies. Recently, it was shown that ADAMTS-13 adopts a folded or an open conformation. Objectives As conformational changes in self-antigens play a role in the pathophysiology of different autoimmune diseases, we hypothesized that the conformation of ADAMTS-13 changes during acute aTTP. Methods Antibodies recognizing cryptic epitopes in the spacer domain were generated. Next, the conformation of ADAMTS-13 in 40 healthy donors (HDs), 99 aTTP patients (63 in the acute phase versus 36 in remission), 12 hemolytic-uremic syndrome (HUS) patients and 63 sepsis patients was determined with ELISA. Results The antibody 1C4 recognizes a cryptic epitope in ADAMTS-13. Therefore, we were able to discriminate between a folded and an open ADAMTS-13 conformation. We showed that ADAMTS-13 in HDs does not bind to 1C4, indicating that ADAMTS-13 circulates in a folded conformation. Similar results were obtained for HUS and sepsis patients. In contrast, ADAMTS-13 of acute aTTP patients bound to 1C4 in 92% of the cases, whereas, in most cases, this binding was abolished during remission, showing that the conformation of ADAMTS-13 is open during an acute aTTP episode. Conclusions Our study shows that, besides absent ADAMTS-13 activity and the presence of anti-ADAMTS-13 autoantibodies, an open ADAMTS-13 conformation is also a hallmark of acute aTTP. Demonstrating this altered ADAMTS-13 conformation in acute aTTP will help to further unravel the pathophysiology of aTTP and lead to improved therapy and diagnosis.
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Affiliation(s)
- E Roose
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
| | - A S Schelpe
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
| | - B S Joly
- Service d'Hématologie biologique, Hôpital Lariboisière, Assistance Publique-Hôpitaux de Paris and EA3518, Institut Universitaire d'Hématologie, Hôpital Saint Louis, Université Paris Diderot, Paris, France
| | - M Peetermans
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - P Verhamme
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - J Voorberg
- Department of Plasma Proteins, Sanquin-Academic Medical Center Landsteiner Laboratory, Amsterdam, the Netherlands
| | - A Greinacher
- Institute for Immunology and Transfusion Medicine, University Medical Center, Greifswald, Germany
| | - H Deckmyn
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
| | - S F De Meyer
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
| | - P Coppo
- Département d'hématologie clinique, Hôpital Saint Antoine, AP-HP and Université Pierre et Marie Curie, Paris, France
| | - A Veyradier
- Service d'Hématologie biologique, Hôpital Lariboisière, Assistance Publique-Hôpitaux de Paris and EA3518, Institut Universitaire d'Hématologie, Hôpital Saint Louis, Université Paris Diderot, Paris, France
| | - K Vanhoorelbeke
- Laboratory for Thrombosis Research, IRF Life Sciences, KU Leuven Campus Kulak Kortrijk, Kortrijk, Belgium
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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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Delcea M, Greinacher A. Biophysical tools to assess the interaction of PF4 with polyanions. Thromb Haemost 2017; 116:783-791. [DOI: 10.1160/th16-04-0258] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 09/07/2016] [Indexed: 11/05/2022]
Abstract
SummaryThe antigen in heparin-induced thrombocytopenia (HIT) is expressed on platelet factor 4 (PF4) when PF4 complexes with polyanions. In recent years, biophysical tools (e. g. circular dichroism spectroscopy, atomic force microscopy, isothermal titration calorimetry, x-ray crystallography, electron microscopy) have gained an important role to complement immunological and functional assays for better understanding the interaction of heparin with PF4. This allowed identification of those features that make PF4 immunogenic (e. g. a certain conformational change induced by the polyanion, a threshold energy of the complexes, the existence of multimeric complexes, a certain number of bonds formed by PF4 with the polyanion) and to characterize the morphology and thermal stability of complexes formed by the protein with polyanions. These findings and methods can now be applied to test new drugs for their potential to induce the HIT-like adverse drug effect by preclinical in vitro testing. The methods and techniques applied to characterize the antigen in HIT may also be helpful to better understand the mechanisms underlying other antibody-mediated disorders in thrombosis and hemostasis (e. g. acquired hemophilia, thrombotic thrombocytopenic purpura). Furthermore, understanding the mechanisms making the endogenous protein PF4 immunogenic may help to understand the mechanisms underlying other autoimmune disorders.
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Brandt S, Krauel K, Jaax M, Renné T, Helm CA, Hammerschmidt S, Delcea M, Greinacher A. Polyphosphates form antigenic complexes with platelet factor 4 (PF4) and enhance PF4-binding to bacteria. Thromb Haemost 2017. [DOI: 10.1160/th15-01-0062] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
SummaryShort chain polyphosphates (polyP) are pro-coagulant and pro-inflammatory platelet released inorganic polymers. The platelet chemokine platelet factor 4 (PF4) binds to lipid A on bacteria, inducing an antibody mediated host defense mechanism, which can be misdirected against PF4/heparin complexes leading to the adverse drug reaction heparin-induced thrombocytopenia (HIT). Here, we demonstrate that PF4 complex formation with soluble short chain polyP contributes to host defense mechanisms. Circular dichroism spectroscopy and isothermal titration calorimetry revealed that PF4 changed its structure upon binding to polyP in a similar way as seen in PF4/heparin complexes. Consequently, PF4/polyP complexes exposed neoepitopes to which human anti-PF4/heparin antibodies bound. PolyP enhanced binding of PF4 to Escherichia coli, hereby facilitating bacterial opsonisation and, in the presence of human anti-PF4/polyanion antibodies, phagocytosis. Our study indicates a role of polyP in enhancing PF4-mediated defense mechanisms of innate immunity.
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Huynh A, Arnold DM, Moore JC, Smith JW, Kelton JG, Nazy I. Development of a high-yield expression and purification system for platelet factor 4. Platelets 2017; 29:249-256. [DOI: 10.1080/09537104.2017.1378808] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Angela Huynh
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Donald M. Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
- McMaster Centre for Transfusion Research, Hamilton, Ontario, Canada
- Canadian Blood Services, Hamilton, Ontario
| | - Jane C. Moore
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - James W. Smith
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - John G. Kelton
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
- McMaster Centre for Transfusion Research, Hamilton, Ontario, Canada
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Sewing S, Roth AB, Winter M, Dieckmann A, Bertinetti-Lapatki C, Tessier Y, McGinnis C, Huber S, Koller E, Ploix C, Reed JC, Singer T, Rothfuss A. Assessing single-stranded oligonucleotide drug-induced effects in vitro reveals key risk factors for thrombocytopenia. PLoS One 2017; 12:e0187574. [PMID: 29107969 PMCID: PMC5673186 DOI: 10.1371/journal.pone.0187574] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 10/23/2017] [Indexed: 12/26/2022] Open
Abstract
Single-stranded oligonucleotides (ON) comprise a promising therapeutic platform that enables selective modulation of currently undruggable targets. The development of novel ON drug candidates has demonstrated excellent efficacy, but in certain cases also some safety liabilities were reported. Among them are events of thrombocytopenia, which have recently been evident in late stage trials with ON drugs. The underlying mechanisms are poorly understood and the risk for ON candidates causing such events cannot be sufficiently assessed pre-clinically. We investigated potential thrombocytopenia risk factors of ONs and implemented a set of in vitro assays to assess these risks. Our findings support previous observations that phosphorothioate (PS)-ONs can bind to platelet proteins such as platelet collagen receptor glycoprotein VI (GPVI) and activate human platelets in vitro to various extents. We also show that these PS-ONs can bind to platelet factor 4 (PF4). Binding to platelet proteins and subsequent activation correlates with ON length and connected to this, the number of PS in the backbone of the molecule. Moreover, we demonstrate that locked nucleic acid (LNA) ribosyl modifications in the wings of the PS-ONs strongly suppress binding to GPVI and PF4, paralleled by markedly reduced platelet activation. In addition, we provide evidence that PS-ONs do not directly affect hematopoietic cell differentiation in culture but at higher concentrations show a pro-inflammatory potential, which might contribute to platelet activation. Overall, our data confirm that certain molecular attributes of ONs are associated with a higher risk for thrombocytopenia. We propose that applying the in vitro assays discussed here during the lead optimization phase may aid in deprioritizing ONs with a potential to induce thrombocytopenia.
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Affiliation(s)
- Sabine Sewing
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
- * E-mail:
| | - Adrian B. Roth
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Michael Winter
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Andreas Dieckmann
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | | | - Yann Tessier
- Roche Pharma Research and Early Development, Roche Innovation Center Copenhagen A/S, Hørsholm, Denmark
| | - Claudia McGinnis
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Sylwia Huber
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Erich Koller
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Corinne Ploix
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - John C. Reed
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Thomas Singer
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
| | - Andreas Rothfuss
- Roche Pharma Research and Early Development, Roche Innovation Center Basel, Basel, Switzerland
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Greinacher A, Selleng K, Warkentin TE. Autoimmune heparin-induced thrombocytopenia. J Thromb Haemost 2017; 15:2099-2114. [PMID: 28846826 DOI: 10.1111/jth.13813] [Citation(s) in RCA: 280] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Indexed: 01/18/2023]
Abstract
Autoimmune heparin-induced thrombocytopenia (aHIT) indicates the presence in patients of anti-platelet factor 4 (PF4)-polyanion antibodies that are able to activate platelets strongly even in the absence of heparin (heparin-independent platelet activation). Nevertheless, as seen with serum obtained from patients with otherwise typical heparin-induced thrombocytopenia (HIT), serum-induced platelet activation is inhibited at high heparin concentrations (10-100 IU mL-1 heparin). Furthermore, upon serial dilution, aHIT serum will usually show heparin-dependent platelet activation. Clinical syndromes associated with aHIT include: delayed-onset HIT, persisting HIT, spontaneous HIT syndrome, fondaparinux-associated HIT, heparin 'flush'-induced HIT, and severe HIT (platelet count of < 20 × 109 L-1 ) with associated disseminated intravascular coagulation (DIC). Recent studies have implicated anti-PF4 antibodies that are able to bridge two PF4 tetramers even in the absence of heparin, probably facilitated by non-heparin platelet-associated polyanions (chondroitin sulfate and polyphosphates); nascent PF4-aHIT-IgG complexes recruit additional heparin-dependent HIT antibodies, leading to the formation of large multimolecular immune complexes and marked platelet activation. aHIT can persist for several weeks, and serial fibrin, D-dimer, and fibrinogen levels, rather than the platelet count, may be helpful for monitoring treatment response. Although standard anticoagulant therapy for HIT ought to be effective, published experience indicates frequent failure of activated partial thromboplastin time (APTT)-adjusted anticoagulants (argatroban, bivalirudin), probably because of underdosing in the setting of HIT-associated DIC, known as 'APTT confounding'. Thus, non-APTT-adjusted therapies with drugs such as danaparoid and fondaparinux, or even direct oral anticoagulants, such as rivaroxaban or apixaban, are suggested therapies, especially for long-term management of persisting HIT. In addition, emerging data indicate that high-dose intravenous immunoglobulin can interrupt HIT antibody-induced platelet activation, leading to rapid platelet count recovery.
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MESH Headings
- Administration, Oral
- Animals
- Anticoagulants/administration & dosage
- Anticoagulants/adverse effects
- Anticoagulants/immunology
- Autoantibodies/blood
- Autoimmunity/drug effects
- Blood Coagulation/drug effects
- Blood Platelets/drug effects
- Blood Platelets/immunology
- Blood Platelets/metabolism
- Heparin/adverse effects
- Heparin/immunology
- Humans
- Immunoglobulins, Intravenous/administration & dosage
- Immunologic Factors/administration & dosage
- Partial Thromboplastin Time
- Platelet Activation/drug effects
- Platelet Factor 4/immunology
- Purpura, Thrombocytopenic, Idiopathic/blood
- Purpura, Thrombocytopenic, Idiopathic/chemically induced
- Purpura, Thrombocytopenic, Idiopathic/drug therapy
- Purpura, Thrombocytopenic, Idiopathic/immunology
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Affiliation(s)
- A Greinacher
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - K Selleng
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - T E Warkentin
- Department of Pathology and Molecular Medicine, Department of Medicine, and McMaster Centre for Transfusion Research, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
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Kizlik-Masson C, Vayne C, McKenzie SE, Poupon A, Zhou Y, Champier G, Pouplard C, Gruel Y, Rollin J. 5B9, a monoclonal antiplatelet factor 4/heparin IgG with a human Fc fragment that mimics heparin-induced thrombocytopenia antibodies. J Thromb Haemost 2017; 15:2065-2075. [PMID: 28771917 DOI: 10.1111/jth.13786] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Indexed: 01/12/2023]
Abstract
Essentials No humanized monoclonal antibody was available to study heparin-induced thrombocytopenia (HIT). We developed the first anti-platelet factor 4 (PF4)/heparin antibody with a human Fc fragment. This antibody (5B9) fully mimics the effects of human HIT antibodies. 5B9 binds two regions within PF4 that may be critical for the pathogenicity of HIT antibodies. SUMMARY Background The diagnosis of heparin-induced thrombocytopenia (HIT) is based on clinical and biological criteria, but a standard is lacking for laboratory assays. Moreover, no humanized HIT antibody is available for pathophysiological studies. Objective To characterise 5B9, a chimeric monoclonal antibody, which fully mimics the effects of human HIT antibodies. Methods/Results 5B9, a chimeric anti-platelet factor 4/heparin complexes IgG1 antibody, was obtained after immunizing specific transgenic mice. 5B9 induced heparin FcγRIIA-dependent platelet aggregation and tissue factor mRNA synthesis in monocytes. It also induced significant thrombocytopenia and thrombin generation in mice expressing human PF4 and FcγRIIA receptors. The binding of 5B9 to PF4/H complexes was inhibited by 15 of 25 HIT plasma samples and only three of 25 samples containing non-pathogenic anti-PF4/H antibodies. KKO, a murine IgG2b HIT antibody, also inhibited the binding of 5B9 to PF4/H, suggesting that epitopes recognized by both antibodies are close. A docking analysis based on VH and VL sequences of 5B9 showed that binding of 5B9 Fab to PF4 involved 12 and 12 residues in B and D monomers, respectively, including seven previously identified as critical to the formation of a PF4/KKO complex. Two regions (Asp-7 to Thr-15 and Ala-32 to Thr-38) therefore appeared important for the binding of 5B9 and KKO on PF4 modified by heparin. Conclusions 5B9 is the first anti-PF4/H monoclonal antibody with a human Fc fragment, which induces similar cellular activation as HIT antibodies. Moreover, 5B9 binds epitopes within PF4 that are likely to be critical for the pathogenicity of HIT antibodies.
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Affiliation(s)
- C Kizlik-Masson
- UMR CNRS 7292 and Université François Rabelais, Tours, France
| | - C Vayne
- UMR CNRS 7292 and Université François Rabelais, Tours, France
- Laboratoire d'Hématologie-Hémostase, CHU Tours, Tours, France
| | - S E McKenzie
- Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA, USA
| | - A Poupon
- PRC, INRA, CNRS, IFCE, Université de Tours, Nouzilly, France
| | - Y Zhou
- Department of Medicine, Cardeza Foundation for Hematologic Research, Thomas Jefferson University, Philadelphia, PA, USA
| | | | - C Pouplard
- UMR CNRS 7292 and Université François Rabelais, Tours, France
- Laboratoire d'Hématologie-Hémostase, CHU Tours, Tours, France
| | - Y Gruel
- UMR CNRS 7292 and Université François Rabelais, Tours, France
- Laboratoire d'Hématologie-Hémostase, CHU Tours, Tours, France
| | - J Rollin
- UMR CNRS 7292 and Université François Rabelais, Tours, France
- Laboratoire d'Hématologie-Hémostase, CHU Tours, Tours, France
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Kim HS, Kim H, Jeong YJ, Lee H, Yim HW, Kim JI, Moon IS, Kim JY. Comparative Analysis of the Suspected Heparin-Induced Thrombocytopenia Level in Korea. Basic Clin Pharmacol Toxicol 2017; 121:360-367. [PMID: 28374942 DOI: 10.1111/bcpt.12791] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/27/2017] [Indexed: 11/28/2022]
Abstract
The primary objective of our study was to evaluate the frequency of suspected heparin-induced thrombocytopenia (HIT) among patients treated with different formulations of heparin and investigate the factors that affect the incidence of HIT. This study is an electronic medical record (EMR)-based large-scale retrospective cohort study conducted from 2009 to 2014 in Korea. After hospitalization, patient platelet count was determined before heparin was prescribed, and all platelet count values obtained during hospitalization were extracted. Suspected HIT was estimated by three 4Ts scores (acute thrombocytopenia, timing onset and other possible causes), which when combined yielded a high probability of HIT. Among 6046 patients enrolled in this study, HIT was suspected in 641 cases (10.6%) and a statistically significant increase in HIT incidence rate was observed for three heparins used (p < 0.001). Dalteparin (HR = 0.55, p = 0.036) and enoxaparin (HR = 0.40, p < 0.001) showed a relatively low HIT incidence rate, compared to unfractionated heparin. Majority of suspected HIT cases (76.9 and 66.7%) occurred in days 8-10 and 5-7 of dalteparin and enoxaparin treatments, respectively. Most of the patients medicated with dalteparin were cancer patients; however, no statistically significant relationship was observed between HIT occurrence and cancer. HIT can cause serious complications, making early diagnosis crucial. Clinical practitioners first prescribing heparin should focus on preventing and detecting complications early by conducting frequent, regular platelet counts before and after heparin administration.
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Affiliation(s)
- Hun-Sung Kim
- Department of Medical Informatics, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Division of Endocrinology and Metabolism, Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Hyunah Kim
- College of Pharmacy, Sookmyung Women's University, Seoul, Korea
| | - Yoo Jin Jeong
- Department of Medical Informatics, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Hyunyong Lee
- Clinical Research Coordinating Center, Catholic Medical Center, The Catholic University of Korea, Seoul, Korea
| | - Hyeon Woo Yim
- Department of Preventive Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Ji Il Kim
- Division of Vascular and Transplant Surgery, Department of Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - In Sung Moon
- Division of Vascular and Transplant Surgery, Department of Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Jang-Yong Kim
- Division of Vascular and Transplant Surgery, Department of Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea
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Anti-platelet factor 4/polyanion antibodies mediate a new mechanism of autoimmunity. Nat Commun 2017; 8:14945. [PMID: 28530237 PMCID: PMC5458132 DOI: 10.1038/ncomms14945] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 02/15/2017] [Indexed: 01/07/2023] Open
Abstract
Antibodies recognizing complexes of the chemokine platelet factor 4 (PF4/CXCL4) and polyanions (P) opsonize PF4-coated bacteria hereby mediating bacterial host defense. A subset of these antibodies may activate platelets after binding to PF4/heparin complexes, causing the prothrombotic adverse drug reaction heparin-induced thrombocytopenia (HIT). In autoimmune-HIT, anti-PF4/P-antibodies activate platelets in the absence of heparin. Here we show that antibodies with binding forces of approximately 60–100 pN activate platelets in the presence of polyanions, while a subset of antibodies from autoimmune-HIT patients with binding forces ≥100 pN binds to PF4 alone in the absence of polyanions. These antibodies with high binding forces cluster PF4-molecules forming antigenic complexes which allow binding of polyanion-dependent anti-PF4/P-antibodies. The resulting immunocomplexes induce massive platelet activation in the absence of heparin. Antibody-mediated changes in endogenous proteins that trigger binding of otherwise non-pathogenic (or cofactor-dependent) antibodies may also be relevant in other antibody-mediated autoimmune disorders. Antibodies against the platelet factor 4 (PF4) support bacterial host defence but in some cases may lead to heparin-induced thrombocytopenia (HIT). Nguyen et al. show that in autoimmune HIT a subset of antibodies binds strongly to PF4 causing its conformational change that leads to association of non-pathogenic PF4 antibodies and thrombotic platelet activation.
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Junqueira DR, Zorzela LM, Perini E. Unfractionated heparin versus low molecular weight heparins for avoiding heparin-induced thrombocytopenia in postoperative patients. Cochrane Database Syst Rev 2017; 4:CD007557. [PMID: 28431186 PMCID: PMC6478064 DOI: 10.1002/14651858.cd007557.pub3] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is an adverse drug reaction presenting as a prothrombotic disorder related to antibody-mediated platelet activation. It is a paradoxical immune reaction resulting in thrombin generation in vivo, which leads to a hypercoagulable state and the potential to initiate venous or arterial thrombosis. A number of factors are thought to influence the incidence of HIT including the type and preparation of heparin (unfractionated heparin (UFH) or low molecular weight heparin (LMWH)) and the heparin-exposed patient population, with the postoperative patient population at higher risk.Although LMWH has largely replaced UFH as a front-line therapy, there is evidence supporting a lack of superiority of LMWH compared with UFH regarding prevention of deep vein thrombosis and pulmonary embolism following surgery, and similar frequencies of bleeding have been described with LMWH and UFH. The decision as to which of these two preparations of heparin to use may thus be influenced by harmful effects such as HIT. We therefore sought to determine the relative impact of UFH and LMWH on HIT in postoperative patients receiving thromboembolism prophylaxis. This is an update of a review first published in 2012. OBJECTIVES The objective of this review was to compare the incidence of heparin-induced thrombocytopenia (HIT) and HIT complicated by venous thromboembolism in postoperative patients exposed to unfractionated heparin (UFH) versus low molecular weight heparin (LMWH). SEARCH METHODS For this update, the Cochrane Vascular Information Specialist searched the Specialised Register (May 2016), CENTRAL (2016, Issue 4) and trials registries. The authors searched Lilacs (June 2016) and additional trials were sought from reference lists of relevant publications. SELECTION CRITERIA We included randomised controlled trials (RCTs) in which participants were postoperative patients allocated to receive prophylaxis with UFH or LMWH, in a blinded or unblinded fashion. Studies were excluded if they did not use the accepted definition of HIT. This was defined as a relative reduction in the platelet count of 50% or greater from the postoperative peak (even if the platelet count at its lowest remained greater than 150 x 109/L) occurring within five to 14 days after the surgery, with or without a thrombotic event occurring in this timeframe. Additionally, we required circulating antibodies associated with the syndrome to have been investigated through laboratory assays. DATA COLLECTION AND ANALYSIS Two review authors independently extracted data and assessed the risk of bias. Disagreements were resolved by consensus with participation of a third author. MAIN RESULTS In this update, we included three trials involving 1398 postoperative participants. Participants were submitted to general surgical procedures, minor and major, and the minimum mean age was 49 years. Pooled analysis showed a significant reduction in the risk of HIT with LMWH compared with UFH (risk ratio (RR) 0.23, 95% confidence interval (CI) 0.07 to 0.73); low-quality evidence. The number needed to treat for an additional beneficial outcome (NNTB) was 59. The risk of HIT was consistently reduced comparing participants undergoing major surgical procedures exposed to LMWH or UFH (RR 0.22, 95% CI 0.06 to 0.75); low-quality evidence. The occurrence of HIT complicated by venous thromboembolism was significantly lower in participants receiving LMWH compared with UFH (RR 0.22, 95% CI 0.06 to 0.84); low-quality evidence. The NNTB was 75. Arterial thrombosis occurred in only one participant who received UFH. There were no amputations or deaths documented. Although limited evidence is available, it appears that HIT induced by both types of heparins is common in people undergoing major surgical procedures (incidence greater than 1% and less than 10%). AUTHORS' CONCLUSIONS This updated review demonstrated low-quality evidence of a lower incidence of HIT, and HIT complicated by venous thromboembolism, in postoperative patients undergoing thromboprophylaxis with LMWH compared with UFH. Similarily, the risk of HIT in people undergoing major surgical procedures was lower when treated with LMWH compared to UFH (low-quality evidence). The quality of the evidence was downgraded due to concerns about the risk of bias in the included studies and imprecision of the study results. These findings may support current clinical use of LMWH over UFH as front-line heparin therapy. However, our conclusions are limited and there was an unexpected paucity of RCTs including HIT as an outcome. To address the scarcity of clinically-relevant information on HIT, HIT must be included as a core harmful outcome in future RCTs of heparin.
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Affiliation(s)
- Daniela R Junqueira
- Evidências em Saúde Publish Company (Brazil); The University of Sydney (Australia)Rua Santa Catarina 760 apto 601, CentroBelo HorizonteMinas Gerais (MG)Brazil30170‐080
| | - Liliane M Zorzela
- University of AlbertaDepartment of Pediatrics8727‐118 streetEdmontonABCanadaT6G 1T4
| | - Edson Perini
- Faculty of Pharmacy, Universidade Federal de Minas Gerais (UFMG)Centro de Estudos do Medicamento (Cemed), Department of Social PharmacyAv Antonia Carlos 6627‐sala 1050‐B2‐Campus PampulhaBelo HorizonteMinas Gerais(MG)Brazil31270‐901
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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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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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Nagler M, Cuker A. Profile of Instrumentation Laboratory's HemosIL® AcuStar HIT-Ab(PF4-H) assay for diagnosis of heparin-induced thrombocytopenia. Expert Rev Mol Diagn 2017; 17:419-426. [PMID: 28271738 DOI: 10.1080/14737159.2017.1304213] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
INTRODUCTION Immunoassays play an essential role in the diagnosis of heparin-induced thrombocytopenia (HIT). The objective of this article is to review HemosIL® AcuStar HIT-Ab(PF4-H) (Instrumentation Laboratory, Bedford, MA, USA), a new chemiluminescent immunoassay for HIT. Areas covered: The authors searched the published literature for evaluation studies of HemosIL® AcuStar HIT-Ab(PF4-H) and sought information from the manufacturer. In this paper, the authors discuss the analytical principle and technical aspects of the assay; describe its diagnostic performance in validation studies; report on its reproducibility, cost-effectiveness, and regulatory status; and discuss the implications of the assay on clinical practice and means of integrating it in diagnostic pathways. HemosIL® AcuStar HIT-Ab(PF4-H) is compared with other rapid assays and widely used enzyme-linked immunoassays for the diagnosis of HIT. Expert commentary: HemosIL® AcuStar HIT-Ab(PF4-H) is automatable, can be performed 24 h per day, offers a rapid turnaround time, and appears to have favorable diagnostic accuracy, particularly at thresholds above that listed in the label. These advantages could lead to improved patient outcomes through rapid provision of results at the point of care, enhancing the accuracy of initial diagnosis.
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Affiliation(s)
- Michael Nagler
- a Department of Haematology and Central Haematology Laboratory , University of Bern , Bern , Switzerland
| | - Adam Cuker
- b Departments of Medicine and Pathology & Laboratory Medicine , University of Pennsylvania , Philadelphia , PA , USA
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Bertini S, Fareed J, Madaschi L, Risi G, Torri G, Naggi A. Characterization of PF4-Heparin Complexes by Photon Correlation Spectroscopy and Zeta Potential. Clin Appl Thromb Hemost 2017; 23:725-734. [PMID: 28118750 DOI: 10.1177/1076029616685430] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is associated with antibodies to complexes between heparin and platelet factor 4 (PF4), a basic protein usually found in platelet alpha granules. Heparin-induced thrombocytopenia antibodies preferentially recognize macromolecular complexes formed between positively charged PF4 and polyanionic heparins over a narrow range of molar ratios. The aim of this work was to study the complexes that human PF4 forms with heparins from various species, such as porcine, bovine, and ovine; heparins from various organs, such as mucosa and lung; and different low-molecular-weight heparins (LMWHs) at several stoichiometric ratios to evaluate their sizes and charges by photo correlation spectroscopy and zeta potential measurements. The resulting data of the PF4 complexes with unfractionated heparins (UFHs), LMWHs and their fractions, and oligosaccharide components suggest that the size of aggregates is not only a simple function of average molecular weight but also of the molecular weight distribution of the sample. Moreover, it was found that lower concentrations of the tested ovine-derived mucosal heparin are required to form the large PF4/heparin complexes as compared to mucosal porcine and bovine heparin.
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Affiliation(s)
- Sabrina Bertini
- 1 G. Ronzoni Institute for Chemical and Biochemical Research, Milan, Italy
| | - Jawed Fareed
- 2 Department of Pathology, Cardiovascular Institute, Loyola University Chicago, Stritch School of Medicine, Maywood, IL, USA
| | - Laura Madaschi
- 1 G. Ronzoni Institute for Chemical and Biochemical Research, Milan, Italy
| | - Giulia Risi
- 1 G. Ronzoni Institute for Chemical and Biochemical Research, Milan, Italy
| | - Giangiacomo Torri
- 1 G. Ronzoni Institute for Chemical and Biochemical Research, Milan, Italy
| | - Annamaria Naggi
- 1 G. Ronzoni Institute for Chemical and Biochemical Research, Milan, Italy
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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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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: 50] [Impact Index Per Article: 6.3] [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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49
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Nguyen TH. Single-molecule force spectroscopy applied to heparin-induced thrombocytopenia. J Mol Recognit 2016; 30. [PMID: 27790761 DOI: 10.1002/jmr.2585] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/13/2016] [Accepted: 09/19/2016] [Indexed: 01/01/2023]
Abstract
Heparin-induced thrombocytopenia (HIT), occurring up to approximately 1% to 5% of patients receiving the antithrombotic drug heparins, has a complex pathogenesis involving multiple partners ranging from small molecules to cells/platelets. Recently, insights into the mechanism of HIT have been achieved by using single-molecule force spectroscopy (SMFS), a methodology that allows direct measurements of interactions among HIT partners. Here, the potential of SMFS in unraveling the mechanism of the initial steps in the pathogenesis of HIT at single-molecule resolution is highlighted. The new findings ranging from the molecular binding strengths and kinetics to the determination of the boundary between risk and non-risk heparin drugs or platelet-surface and platelet-platelet interactions will be reviewed. These novel results together have contributed to elucidate the mechanisms underlying HIT and demonstrate how SMFS can be applied to develop safer drugs with a reduced risk profile.
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Affiliation(s)
- Thi-Huong Nguyen
- Institute for Immunology and Transfusion Medicine, University Medicine Greifswald, 17475, Greifswald, Germany.,ZIK HIKE - Center for Innovation Competence, Humoral Immune Reactions in Cardiovascular Diseases, University of Greifswald, 17489, Greifswald, Germany
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50
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Samhouri Y, Telfah M, Kouides R, Woodlock T. Utilization of 4T score to determine the pretest probability of heparin-induced thrombocytopenia in a community hospital in upstate New York. J Community Hosp Intern Med Perspect 2016; 6:32522. [PMID: 27609736 PMCID: PMC5016743 DOI: 10.3402/jchimp.v6.32522] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/01/2016] [Indexed: 11/14/2022] Open
Abstract
Background Thrombocytopenia is common in hospitalized patients. Heparin-induced thrombocytopenia (HIT) is a life-threatening condition which can lead to extensive thrombosis. Diagnosis of HIT relies on clinical suspicion determined by 4T score and immunoassays through testing for anti-PF4/heparin antibodies. Clinical practice guidelines published by the American Society of Hematology in 2013 recommended use of the 4T score before ordering the immunoassays as a measure of pretest probability. The purpose of this study was to evaluate the utilization of 4T score before ordering anti-PF4/heparin antibodies at Unity Hospital. Methods We did a retrospective chart review for patients who are 18 years or older, admitted to Unity Hospital between July 1, 2013, and December 31, 2014, and had anti-PF4/heparin antibodies ordered. Subjects who had prior history of HIT or had end-stage renal disease on hemodialysis were excluded. After calculating 4T score retrospectively, we calculated the proportion of patients who had 4T score documented prior to ELISA testing and proportion of ELISA tests, which were not indicated due to a 4T score less than or equal to 3 using Minitab 16. Results Review of 123 patients, with an average age of 69.4 years, showed that testing was indicated in 18 patients. Six subjects had positive results, and testing was indicated in all of them. 4T score was documented in three patients. This quality improvement study showed that 4T score documentation rate at Unity Hospital is 2.4%. Anti-PF4/heparin antibody testing was indicated in 14.6%. This test is being overused in thrombocytopenia work up at Unity Hospital, costing $9,345. The topic was reviewed for residents. A prompt and calculator for 4T score were added to electronic medical records before ordering the test as a step to improve high value care.
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Affiliation(s)
- Yazan Samhouri
- Department of Medicine, Rochester Regional Health-Unity Hospital, Rochester, NY, USA;
| | - Mohammad Telfah
- Department of Medicine, Rochester Regional Health-Unity Hospital, Rochester, NY, USA
| | - Ruth Kouides
- Department of Medicine, Rochester Regional Health-Unity Hospital, Rochester, NY, USA
| | - Timothy Woodlock
- Department of Medicine, Rochester Regional Health-Unity Hospital, Rochester, NY, USA.,Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY, USA
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