凝血因子XI多肽抑制剂的开发及抗血栓作用研究

Thrombotic diseases are leading causes of death and disability worldwide. Clinically used anticoagulants impair patients’ normal hemostasis and bring about high risk of severe bleeding. In this project, we aim at developing small peptides for mediating the activity of the activated coagulation factor XI (fXIa), which has been recently suggested as a safer antithrombotic target. In our previous study, we developed a strategy for designing and screening peptidic inhibitors of serine proteases. We hereby propose to optimize the development strategy and generate high-affinity and high-specificity peptidic inhibitors of fXIa through rational design and directed evolution. We will also study the inhibitory mechanism of these peptides with multiple biochemical and biophysical approaches. Meanwhile, the antithrombotic efficacy and safety of the inhibitors will be evaluated in different animal models. The purpose of this project is to further improve the strategy of peptidic inhibitor development and to provide high-potency and high-safety candidates of anticoagulants for antithrombotic therapy.

血栓类疾病严重威胁人类生命健康，但目前临床上常用的抗凝剂对患者的正常凝血功能（伤口愈合等）会产生较大损伤，增加严重出血的风险。近年来，许多研究表明凝血因子XI（fXIa）是一种具有较高安全性的血栓类疾病治疗靶标，但靶向fXIa的药物的开发尚处于起步阶段。因此，本项目将致力于开发调控fXIa活性的小型多肽类药物，进而抑制血栓的形成。本项目将基于并优化申请人之前发明的丝氨酸水解酶多肽抑制剂的开发方法，利用理性设计和定向演化等技术筛选高效、专一的fXIa多肽抑制剂，并在分子水平研究其作用机制。另外，本项目还将在动物模型上评估抑制剂的抗血栓效果及安全性。在进一步完善丝氨酸水解酶多肽抑制剂的开发方法的同时，为血栓类疾病的治疗提供更加安全、高效的抗凝剂先导药物。

凝血因子XIa（Coagulation factor XIa, FXIa）近年来被认为是相对于传统抗凝剂靶向的凝血酶和FXa更安全的血栓治疗和预防的靶标，因为抑制FXIa的活性在抑制血栓形成的同时不会带来严重的出血风险。本项目开发了半数抑制浓度在nM级别的小分子和多肽类FXIa抑制剂，并且通过X-射线晶体学和分子动力学模拟解释其抑制机理。在后续工作中，我们用多种动物血栓模型评价了抑制剂的抗血栓效果及出血风险。我们开发的FXIa抑制剂在同剂量表现出和目前临床主流抗凝剂相当的抗血栓效果，并且带来更小的出血风险。同时，我们对本课题进行了拓展，开发了靶向凝血系统调节系统纤溶系统的抗凝小分子先导药物和多肽抑制剂，并建立相关动物疾病模型评价其抑制机理。本项目的完成不但提供了多种新型的抗凝先导药物，同时完善了一套开发丝氨酸蛋白酶多肽抑制剂的普适方法。