Contribution of Plasma and Platelet Factor XIII to Venous Thrombosis

项目总结/摘要 静脉血栓形成/血栓栓塞（VTE）导致全球约1000万例病例， 每年有10万到30万人死亡即使接受治疗，30-50%的VTE患者也会发生复发性VTE或 患有使人衰弱长期健康并发症，例如血栓形成后综合征和/或肺 高血压普遍存在的临床问题是，目前的抗凝治疗与 出血的显著风险，因此开发了减少血栓形成的靶向抗凝剂 而不增加出血的风险是必要的。我们最近发现，因子XIII（FXIII） 介导血凝块中的红细胞保留并决定血凝块大小。重要的是，我们已经证明，抑制FXIII 活性或阻断FXIII-纤维蛋白原相互作用可降低血凝块RBC含量， 体外和体内血栓尺寸。这一观察结果表明，抑制FXIII活性或阻断FXIII- 纤维蛋白原的相互作用代表了降低静脉血栓栓塞风险的一种新方法。此应用程序的主要目标是 确定FXIII介导VTE的分子机制有三个具体目的：1）确定 血浆和血小板FXIII对体外和体内凝块组成和重量的相对贡献，2） 确定V34 L多态性加速FXIII活化对血凝块组成的贡献， 体外和体内的重量，和3）测定FXIII的水平，其降低血栓重量而不增加 流血了将在血浆和生理相关全血系统中研究凝块形成。本研究 将应用生物化学和遗传学工具的组合来解决FXIII活性对RBC保留的作用 在VTE和止血的体外和体内模型中的全血凝块形成期间。该研究计划将 极大地丰富了我的技术能力，并培养我成为一名独立的调查员。通过支持性 课程，各种研讨会，并参加国家和国际会议，我将扩大我的 科学知识，以解决悬而未决的问题，有关凝血研究。与此同时， 拟议的研究将大大推进我们对FXIII活性和激活作用的理解， 血栓形成和组成的动力学。这项研究是高度创新的，因为它调查了一部小说， 假设阻断FXIII活性将减少血栓大小，从而减少VTE。这种方法 与现有疗法有根本不同，因为它不会干扰凝块上游的因子 纤维蛋白网络形成，因此预期不会像传统抗凝剂那样导致出血风险。最后， 这些发现将通过提供关于FXIII在VTE中的作用的信息来推进该领域， 具有重要意义，有可能产生一种新的靶点，以降低VTE风险。

PROJECT SUMMARY/ABSTRACT Venous thrombosis/thromboembolism (VTE) results in approximately 10 million cases worldwide and between 100,000 and 300,000 deaths yearly. Even with treatment, 30-50% of VTE patients develop recurrent VTE or suffer debilitating long-term health complications such as post-thrombotic syndrome and/or pulmonary hypertension. The prevailing clinical problem is that current anticoagulation therapies are associated with a significant risk of hemorrhage, thus the development of targeted anticoagulant agents which reduce thrombosis without increasing the risk of bleeding is necessary. We have recently discovered that factor XIII (FXIII) mediates RBC retention in clots and determines clot size. Importantly, we have shown that inhibiting FXIII activity or blocking FXIII-fibrinogen interactions reduces clot RBC content, and consequently, decreases thrombus size in vitro and in vivo. This observation suggests that inhibiting FXIII activity or blocking FXIII- fibrinogen interactions represents a new approach to reduce VTE risk. The primary goal of this application is to determine the molecular mechanisms by which FXIII mediates VTE in three Specific Aims: 1) Determine the relative contributions of plasma and platelet FXIII to clot composition and weight in vitro and in vivo, 2) Determine the contribution of accelerated FXIII activation by V34L polymorphism to clot composition and weight in vitro and in vivo, and 3) Determine the level of FXIII that reduces thrombus weight without increasing bleeding. Clot formation will be studied in plasma and physiologically-relevant whole blood systems. This study will apply a combination of biochemical and genetic tools to address the role of FXIII activity on RBC retention during whole blood clot formation in in vitro and in vivo models of VTE and hemostasis. This research plan will greatly enrich my technical abilities and train me to be an independent investigator. Through supportive coursework, diverse seminars, and participation at national and international conferences, I will expand my scientific knowledge to address unanswered questions pertinent to coagulation research. Concurrently, the proposed research will significantly advance our understanding of the role of FXIII activity and activation kinetics in thrombus formation and composition. This study is highly innovative because it investigates a novel hypothesis that blocking FXIII activity will reduce thrombus size, and consequently, VTE. This approach is fundamentally different than existing therapies because it would not interfere with factors upstream of the clot fibrin network formation and thus, is not expected to result in bleeding risk as traditional anticoagulants. Finally, these findings will advance the field by providing information on the role of FXIII in VTE and is clinically significant with the potential to yield a novel target to reduce VTE risk.