New approaches to the pathophysiology, diagnosis and management of heparin-induced thrombocytopenia

肝素诱导的血小板减少症的病理生理学、诊断和治疗的新方法

• 批准号: 10276062
• 负责人: Anand Padmanabhan
• 金额: $ 39.75万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2026-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10276062
• 关键词: Affect; Alpha Granule; American Society of Hematology; Antibodies; Anticoagulant therapy; Anticoagulants; Anticoagulation; Antigens; Area; Benign; Binding; Biochemical; Biological Assay; Blood Platelets; Blood specimen; Cessation of life; Characteristics; Chondroitin Sulfate A; Chondroitin Sulfates; Chromatography; Coagulation Process; Complex; Dangerousness; Data; Development; Diagnosis; Diagnostic; Diagnostic Procedure; Diagnostic tests; Disease; Early Diagnosis; Environment; Enzyme-Linked Immunosorbent Assay; Epidemic; Evaluation; Event; Functional disorder; Generations; Goals; Gold; Hemorrhage; Heparin; Heparin Binding; Heterogeneity; Hospitals; In Vitro; Institution; Laboratories; Lead; Length; Life; Mediating; Methods; Monoclonal Antibodies; Morbidity - disease rate; Outcome; P-Selectin; PF4 Gene; Pathogenesis; Pathogenicity; Pathway interactions; Patient Isolation; Patients; Platelet Activation; Proteins; Research; Research Infrastructure; Research Personnel; Risk; Sampling; Serology; Serotonin; Specificity; Sulfate; Surface; Syndrome; Testing; Therapeutic; Thrombin; Thrombocytopenia; Thrombosis; Time; Whole Blood; Work; accurate diagnosis; base; drug candidate; heparin-induced thrombocytopenia; improved; in vivo; inhibitor/antagonist; innovation; insight; mortality; mouse model; murine monoclonal antibody; new therapeutic target; novel; novel strategies; prevent; rapid diagnosis

PROJECT SUMMARY/ABSTRACT Heparin-induced thrombocytopenia (HIT) is a severe, antibody (ab)-mediated prothrombotic syndrome with high morbidity and mortality. The biochemical basis of the distinction between “pathogenic” platelet-activating antibodies and “benign” non-activating HIT antibodies is not well understood. This results in significant diagnostic challenges and in excessive use of non-heparin alternative anticoagulation that have worse bleeding profiles than heparin. Outcomes in HIT are suboptimal despite current therapy with direct thrombin inhibitors: One-third of affected patients develop thrombosis and one in ten patients dies. The proposed studies will explore key unanswered questions in areas of HIT pathophysiology, diagnosis and treatment. For Aim 1, we hypothesize the existence of multiple functional classes of HIT antibodies: (1) Pathogenic antibodies that recognize PF4-treated platelets with or without reactivity to PF4-heparin complexes, and (2) Benign abs that recognize PF4-heparin but not platelets treated with PF4. We will identify and characterize these antibody classes by chromatography-based isolation from patient samples and will generate novel HIT monoclonal antibodies in each of these functional classes. Generated monoclonal antibodies will be tested for pathogenicity in a HIT mouse model and results will be correlated with their serologic characteristics. Obtaining and processing normal donor platelets is a major challenge that limits the availability of functional “gold standard” testing in HIT. In Aim 2, we will develop a rapid HIT diagnostic test using the patient’s own platelets treated with PF4/heparin. This will facilitate “in-hospital” HIT diagnosis leading to early detection of this condition. Currently used non-heparin alternative anticoagulants do not address the most proximal event in HIT: Activation of platelets by HIT antibodies. Given this, breakthrough thrombosis is frequently seen in patients under treatment and so is unintended bleeding caused by the potent non-heparin anticoagulants used. In Aim 3, we will use platelet-derived and synthetic chondroitin sulfates of various sulfation levels and saccharide lengths to evaluate their ability to inhibit HIT-antibody mediated platelet activation in vitro and to ameliorate thrombocytopenia in a HIT murine model. In Aim 1, we expect to successfully separate and characterize multiple functional classes of HIT antibodies which will suggest new ways to selectively detect only the pathogenic ones. Developing and optimizing a diagnostic method using the patient’s own platelets in Aim 2 will transform platelet-activation based HIT testing by moving it from the reference laboratory environment to the in-hospital setting. Finally, studies described in Aim 3 will introduce a new class of therapeutics in HIT, chondroitin sulfates, that will prevent thrombosis, but unlike current therapies, will not increase the risk of bleeding. In summary, we anticipate that all three aims of this proposal will lead to a significant impact on pathophysiology, diagnosis and treatment of HIT.

项目概要/摘要 肝素诱导的血小板减少症 (HIT) 是一种严重的抗体 (ab) 介导的血栓前综合征 发病率和死亡率高。区分“致病性”血小板激活剂和血小板激活剂的生化基础 抗体和“良性”非激活 HIT 抗体尚不清楚。这导致显着 诊断挑战和过度使用非肝素替代抗凝药物会导致病情恶化 出血情况优于肝素。尽管目前使用直接凝血酶治疗，HIT 的结果仍不理想 抑制剂：三分之一受影响的患者出现血栓，十分之一的患者死亡。拟议的研究 将探讨 HIT 病理生理学、诊断和治疗领域尚未解答的关键问题。对于目标 1， 我们假设存在多种功能类别的 HIT 抗体：(1) 致病性抗体 识别 PF4 处理的血小板，对 PF4-肝素复合物有或没有反应性，以及 (2) 良性腹肌 识别 PF4-肝素，但不识别经 PF4 处理的血小板。我们将鉴定并表征这些抗体 通过基于色谱法从患者样本中分离来进行分类，并将生成新型 HIT 单克隆抗体 每个功能类别的抗体。生成的单克隆抗体将进行测试 HIT 小鼠模型中的致病性和结果将与其血清学特征相关。获取 处理正常供体血小板是一个重大挑战，限制了功能性“黄金”的可用性 HIT 中的“标准”测试。在目标 2 中，我们将使用患者自身的血小板开发快速 HIT 诊断测试 用PF4/肝素治疗。这将有助于“院内”HIT 诊断，从而及早发现这种情况 健康）状况。目前使用的非肝素替代抗凝剂不能解决最近发生的事件 HIT：HIT 抗体激活血小板。鉴于此，突破性血栓形成常见于 正在接受治疗的患者等是由使用强效非肝素抗凝剂引起的意外出血。 在目标 3 中，我们将使用各种硫酸化水平的血小板衍生的和合成的硫酸软骨素， 糖长度来评估其在体外抑制 HIT 抗体介导的血小板活化的能力，并 改善 HIT 小鼠模型中的血小板减少症。在目标 1 中，我们期望成功分离并 表征 HIT 抗体的多种功能类别，这将提出选择性检测的新方法 只有致病的。使用患者自身的血小板开发和优化诊断方法 目标 2 将改变基于血小板激活的 HIT 测试，将其从参考实验室移出 环境与医院内的环境相适应。最后，目标 3 中描述的研究将引入一类新的 HIT 疗法，硫酸软骨素，可以预防血栓形成，但与目前的疗法不同，不会 增加出血风险。总之，我们预计该提案的所有三个目标都将导致 对HIT的病理生理学、诊断和治疗产生重大影响。