Role of GPIba Receptor Shedding in Platelet Dysfunction Following Trauma

GPIba 受体脱落在创伤后血小板功能障碍中的作用

• 批准号: 8782926
• 负责人: Jessica Cardenas
• 金额: $ 5.33万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2016-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8782926
• 关键词: Accounting; Adhesions; Admission activity; Agonist; Animals; Binding; Blood; Blood Coagulation Disorders; Blood Platelets; Blood Transfusion; Blood specimen; Cause of Death; Cessation of life; Clinical; Coagulation Process; Data; Endothelium; Enzyme Inhibition; Enzyme Inhibitor Drugs; Enzyme Inhibitors; Enzyme-Linked Immunosorbent Assay; Enzymes; Fellowship; Fibrin; Flow Cytometry; Functional disorder; Glycoproteins; Goals; Hemorrhage; Hemorrhagic Shock; Hemostatic Agents; Hemostatic function; Human; Injury; Intervention; Knockout Mice; Life; Liquid substance; Measures; Mediating; Mission; Morbidity - disease rate; Mus; Nature; Outcome; Patients; Peptide Hydrolases; Phospholipids; Plasma; Platelet Activation; Platelet aggregation; Process; Proteolysis; Public Health; Research; Resuscitation; Ristocetin; Role; Surface; Testing; Therapeutic; Time; Transfusion; Trauma; Tumor Necrosis Factor Receptor; Tumor Necrosis Factor-alpha; United States; United States National Institutes of Health; Wild Type Mouse; blood product; combat; enzyme activity; experience; improved; injured; innovation; mortality; mouse model; patient population; public health relevance; receptor; receptor expression; response; scaffold; therapeutic target; von Willebrand Factor; von Willebrand factor receptor

DESCRIPTION (provided by applicant): Traumatic injury is the third leading cause of death in the US and about 40% of these deaths are due to hemorrhage. One quarter of all trauma patients experience prolonged hemorrhage due to impaired blood clotting (coagulopathy). These patients suffer from excessive bleeding disproportionate to their injuries, a phenomenon that is poorly understood. Achieving hemostasis following injury is crucial to controlling blood loss and platelets are critical regulators of this process. Platelet adhesion to damaged endothelium is mediated by von Willebrand factor (vWF) binding to the GPIb¿ receptor on activated platelets. Preliminary data show that platelet adhesion to vWF was significantly reduced following injury. In addition, these patients displayed reduced platelet GPIb¿ receptor expression and increased shedding of GPIb¿ into the plasma, suggesting a possible mechanism behind defective platelet-vWF adhesion. The long-term goal is to understand the contribution of platelet receptor shedding to platelet dysfunction and bleeding in trauma patients. Shedding of GPIb¿ is proteolytically regulated by tumor necrosis factor-¿ converting enzyme (TACE), which modulates platelet-vWF adhesion through cleavage of GPIb¿. Preliminary clinical results show a substantial increase in TACE expression on platelets following injury. Therefore, the objective of this application is to determine the contribution of TACE-mediated GPIb¿ receptor shedding to the defective platelet-vWF adhesion observed following traumatic injury. The central hypotheses are: 1) Excessive hemorrhage in trauma patients results from defective platelet-vWF adhesion due to inappropriate shedding of GPIb¿; 2) This shedding is mediated by elevated TACE, and can be corrected through TACE inhibition. The rationale for this research is that understanding the effects of injury on platelet-vWF binding will allow identification of the mechanisms behind life-threatening hemorrhage and develop pharmacologic interventions to alleviate bleeding. These hypotheses will be tested by pursuing two specific aims: 1) Identify the mechanisms behind defective platelet-vWF adhesion following traumatic injury; and 2) Characterize the effect of TACE absence and inhibition on platelet GPIb¿ receptor expression and hemostasis in a mouse model of trauma and hemorrhage. Under the first aim, serial blood samples will be collected from severely injured patients to measure effects of injury and resuscitation fluids on expression of platelet GPIb¿ and TACE by flow cytometry and shedding of GPIb¿ by ELISA. Under the second aim, TACE absence and inhibition will be tested in a mouse model using both platelet-specific TACE knock-out mice and TACE inhibitors in wild-type mice to determine the effects of TACE absence and inhibition on preserving GPIb¿ receptor expression. This approach is innovative because it utilizes both human and animal subjects and a unique patient population rarely studied in the lab setting. The proposed research is significant because the results will identify strategies to facilitate more effective platelet- vWF binding, which could subsequently improve primary hemostasis in hemorrhaging trauma patients.

描述（由申请人提供）：创伤性损伤是美国第三大死亡原因，其中约 40% 的死亡是由于出血造成的。四分之一的创伤患者因凝血功能受损（凝血病）而经历长时间出血。这些患者的出血量与其所受的伤害不成比例，但人们对这种现象知之甚少。受伤后实现止血对于控制失血至关重要，而血小板是该过程的关键调节剂。血小板与受损内皮的粘附是通过与活化血小板上的 GPIb 受体结合的冯维勒布兰德因子 (vWF) 介导的。初步数据表明，损伤后血小板对 vWF 的粘附显着减少。此外，这些患者表现出血小板 GPIb 受体表达减少，并且 GPIb 进入血浆的量增加，这表明血小板-vWF 粘附缺陷背后的可能机制。长期目标是了解血小板受体脱落对创伤患者血小板功能障碍和出血的影响。 GPIb 的脱落受到肿瘤坏死因子转换酶 (TACE) 的蛋白水解调节，该酶通过 GPIb 的裂解调节血小板-vWF 粘附。初步临床结果显示损伤后血小板上 TACE 表达大幅增加。因此，本申请的目的是确定 TACE 介导的 GPIb 受体脱落对创伤性损伤后观察到的血小板-vWF 粘附缺陷的影响。中心假设是： 1) 创伤患者的过度出血是由于 GPIb 不适当脱落导致血小板与 vWF 粘附缺陷所致； 2) 这种脱落是由 TACE 升高介导的，可以通过 TACE 抑制来纠正。这项研究的基本原理是，了解损伤对血小板-vWF 结合的影响将有助于识别危及生命的出血背后的机制，并开发药物干预措施来减轻出血。这些假设将通过追求两个具体目标来检验：1）确定创伤性损伤后血小板-vWF 粘附缺陷背后的机制； 2) 表征创伤和出血小鼠模型中 TACE 缺失和抑制对血小板 GPIb 受体表达和止血的影响。第一个目标是从严重受伤的患者身上采集连续的血液样本，通过流式细胞术测量损伤和复苏液对血小板 GPIb 和 TACE 表达的影响，并通过 ELISA 测量 GPIb 脱落的影响。在第二个目标下，将使用血小板特异性 TACE 敲除小鼠和野生型小鼠中的 TACE 抑制剂在小鼠模型中测试 TACE 缺失和抑制，以确定 TACE 缺失和抑制对保留 GPIb 受体表达的影响。这种方法具有创新性，因为它同时利用了人类和动物受试者以及实验室环境中很少研究的独特患者群体。拟议的研究意义重大，因为结果将确定促进更有效的血小板-vWF结合的策略，从而随后改善出血性创伤患者的初步止血。