Complement and Thrombosis in HIT

HIT 中的补体和血栓形成

• 批准号: 10319182
• 负责人: Gowthami M Arepally
• 金额: $ 59.96万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-12-15 至 2024-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10319182
• 关键词: Address; Affect; Allergic Reaction; Amputation; Antibodies; Anticoagulants; Anticoagulation; Antigen-Antibody Complex; Antigens; Binding; Biological Assay; Blood Platelets; Cell surface; Cells; Cessation of life; Charge; Classical Complement Pathway; Clinical; Clinical Research; Coagulation Process; Complement; Complement 1q; Complement 2; Complement 3a; Complement 5a; Complement Activation; Complement Inactivators; Complement Membrane Attack Complex; Complement Receptor; Data; Deposition; Disease; Effectiveness; Endothelial Cells; Endothelium; Factor Xa; Future; Hemorrhage; Heparin; Heparin Binding; Immunoglobulin G; Impairment; Inflammation; Intervention; Investigation; Knowledge; Laboratory Study; Life; Lytic; Maximum Tolerated Dose; Mediating; Microfluidics; Modeling; Morbidity - disease rate; Mus; Nonlytic; Outcome; PF4 Gene; Pathogenesis; Pathway interactions; Patients; Plasma; Predisposition; Procedures; Publishing; Recurrence; Regulation; Risk; Role; Safety; Signal Transduction; Surface; Testing; Therapeutic; Thrombin; Thromboembolism; Thromboplastin; Thrombosis; Thrombus; Time; Whole Blood; activation product; allergic response; base; cell injury; clinically relevant; complement 1q receptor; complement C3 precursor; complement pathway; design; efficacy evaluation; endothelial cell procoagulant activity; heparin-induced thrombocytopenia; high risk; in vivo; inhibitor; insight; light scattering; monocyte; mortality risk; mouse model; neutrophil; novel; potential biomarker; pre-clinical; prevent; public health relevance; response; seropositive; thrombotic complications; treatment strategy; von Willebrand Factor

ABSTRACT Heparin induced thrombocytopenia (HIT) is a severe thrombotic disorder initiated by ultralarge immune complexes (ULICs) containing IgG antibodies to a multivalent antigen composed of platelet factor 4 (PF4) and heparin (H). Patients with HIT are at risk for death, amputation, recurrent thromboembolism and bleeding while receiving maximally tolerated doses of factor Xa or direct thrombin inhibitors (DTIs). Thus, there is an unmet need for deeper insight into the pathobiology of thrombosis in HIT that will lead to targeted novel non- anticoagulant interventions to supplement contemporary therapy. Our published and pilot data demonstrate that activation of the complement pathway fulfills this gap. Specifically, we show that HIT ULICs: 1) interact and bind complement components and von Willebrand factor (vWF) multimers, 2) generate soluble complement components via the classical pathway, 3) deposit C3 on neutrophils, monocytes and endothelial cells (ECs), 4) trigger complement-dependent neutrophil degranulation, monocyte tissue factor (TF) and procoagulant activity upstream of C5, 5) activate complement even in the presence of DTIs, and 6) promote complement deposition in a murine thrombosis model of HIT. Based on these findings, we hypothesize that complement activation by HIT ULICs contributes to the prothrombotic state in HIT through direct EC injury mediated by surface expressed complement receptors (CRs) and by amplifying signaling by promoting cooperativity with FcRIIA on neutrophils and monocytes. We will address the following specific aims: 1) Examine HIT ULIC-complement interactions and effects of complement activation on ECs We will test the hypothesis that incorporation of complement enlarges and stabilizes assembled ULICs, impairs complement regulatory function, and promotes EC injury leading to release of vWF multimers that further amplify ULIC formation and complement activation. 2) Examine cooperative interactions of HIT ULICs, complement and monocyte/neutrophil FcR. We will test the hypothesis that complement-containing ULICS amplify FcRIIA signaling by promoting cooperativity with cellular CRs on neutrophils and monocytes. We will examine the effects of ULIC composition on cell activation, identify CRs involved in binding HIT ULICs, study soluble and cellular complement regulatory mechanisms, and characterize complement activation in seropositive patients with and without HIT. 3) Examine complement inhibition as a therapeutic strategy for thrombosis in HIT. We will use microfluidic assays and murine thrombosis models to test the hypothesis that activation of the classical complement pathway by HIT ULICs promotes macrovascular thrombosis through release of vWF from activated ECs and amplification of cellular procoagulant activity. We will examine the efficacy of proximal and terminal complement pathway inhibition as a strategy to lower the intensity of antithrombotic therapy needed to treat HIT. Together, these studies will provide new insights into IC- mediated thrombosis broadly and provide a detailed mechanistic pathway for complement inhibition as a rationale, potent and non anticoagulant-dependent strategy for the treatment of HIT.

抽象的 肝素诱导的血小板减少症（HIT）是一种严重的血栓性疾病 含有由血小板因子4（PF4）和 肝素（H）。患有命中的患者有死亡，截肢，复发性血栓栓塞和出血的风险 接受最大耐受剂量的因子Xa或直接凝血酶抑制剂（DTI）。那是一个未满足的 需要更深入地了解HIT中血栓形成的病理学，这将导致有针对性的新型非 - 补充当代疗法的抗凝干预措施。我们已发布和试点数据表明 完成途径的激活达到了这一差距。具体来说，我们显示了命中率：1）互动和绑定 补体组件和von Willebrand因子（VWF）多聚体，2）生成固体完成 通过经典途径的组件，3）将C3沉积在中性粒细胞，单核细胞和内皮细胞（ECS）上，4） 触发补体依赖性嗜中性粒细胞程度，单核细胞组织因子（TF）和促凝活性 C5的上游，5）即使存在DTI，也可以激活完成，6）促进完成沉积 在鼠的鼠血栓形成模型中。基于这些发现，我们假设通过 HIT ULICS通过表达的表面介导的直接EC损伤造成了促血栓形成状态 补体受体（CRS）和通过在中性粒细胞上促进与FCRIIA的协调来扩增信号传导 和单核细胞。我们将解决以下具体目的：1）检查命中ULIC-COMPLENT交互和 完成激活对ECS的影响我们将测试融合增强功能的假设 并稳定组装的ULIC，损害完成调节功能，并促进EC伤害 释放VWF多聚体，以进一步扩大ULIC的形成和完成激活。 2）检查 热门ulics，完成和单核细胞/中性粒细胞FCR的合作相互作用。我们将检验假设 补体含ulics通过促进与细胞CRS的协调来扩大FCRIIA信号传导 中性粒细胞和单核细胞。我们将检查Ulic成分对细胞激活的影响，识别CRS 参与结合命中率，研究固体和细胞补体调节机制，并表征 有或没有命中的血清阳性患者的补体激活。 3）检查完成抑制作用 血栓形成的治疗策略。我们将使用微流体测定和鼠血栓形成模型 检验以下假设，即受到命中的经典补体途径的激活促进了大血管 通过从活化的EC中释放VWF的血栓形成并扩增细胞凝聚活性。我们 将审查近端和末端完成途径抑制的效率，以此作为降低的策略 抗血栓疗法的强度需要治疗命中。这些研究将共同​​提供有关IC-的新见解 介导的血栓形成广泛，并为完成抑制作用提供了详细的机械途径 基本原理，潜在和非抗凝剂依赖性策略用于治疗命中率。