Factor VIIa interaction with Endothelial Cell Protein C Receptor

因子 VIIa 与内皮细胞蛋白 C 受体的相互作用

• 批准号: 9328143
• 负责人: Vijaya Mohan Rao Lella
• 金额: $ 36.78万
• 依托单位: UNIVERSITY OF TEXAS HLTH CTR AT TYLER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-01-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9328143
• 关键词: Acute; Adult; Anti-Inflammatory Agents; Anti-inflammatory; Antibodies; Anticoagulants; Binding; Biodistribution; Biological; Biological Models; Blood Circulation; Blood Coagulation Disorders; Blood Coagulation Factor; Blood Vessels; Bypass; Childhood; Clinical Treatment; Coagulation Process; Data; Development; Dimensions; Down-Regulation; Emergency Situation; Endothelial Cells; Endothelium; Extravasation; F8 gene; Factor VIIa; Factor Va; Fc Receptor; Funding; Generations; Hemophilia A; Hemorrhage; Hemostatic Agents; Hemostatic function; In Vitro; Inflammation; Injury; Joints; Knee Injuries; Knowledge; Laboratories; Lead; Ligands; Ligation; Mediating; Mus; Needles; Outcome; PAR-1 Receptor; Pathway interactions; Patients; Pharmacology; Phospholipids; Play; Positioning Attribute; Prevention; Prophylactic treatment; Protein C; Prothrombin; Puncture procedure; Recombinants; Role; Saphenous Vein; Signal Transduction; Site; Testing; Therapeutic; Thrombin; Thromboplastin; Time; Tissues; Transgenic Mice; Variant; Work; activated Protein C; activated protein C receptor; arthropathies; base; bone loss; clinical efficacy; cofactor; cost; cost effective; design; improved; in vivo; in vivo Model; inhibitor/antagonist; joint destruction; joint injury; novel; novel therapeutics; prevent; prophylactic; protective effect; protein activation; public health relevance; receptor; recombinant FVIIa

 DESCRIPTION (provided by applicant): Recent studies showed that clotting factor FVIIa (FVIIa), which initiates the coagulation cascade upon binding to procoagulant cofactor tissue factor (TF) following vascular injury, also binds to anticoagulant cofactor endothelial cell protei C receptor (EPCR). EPCR plays a critical role in the protein C anticoagulant pathway by promoting the activation of protein C. EPCR also promotes activated protein C (APC)-induced cytoprotective signaling. Studies conducted in the last funding cycle revealed that FVIIa binding to EPCR on the endothelium facilitates the transport of FVII/FVIIa from the circulation to extravascular sites and FVIIa bound to EPCR activates the protease-activated receptor 1 (PAR1)-mediated cell signaling and provides the barrier protective effect. Pharmacological concentrations of rFVIIa were found to displace endogenous protein C from EPCR. rFVIIa is routinely used to treat hemophilia patients with inhibitory antibodies against FVIII and FIX. It is also being used as an emergency hemostatic agent in both pediatric and adult patients. Despite its widespread and successful use, the understanding of the mechanism of rFVIIa action in bleeding disorders is incomplete. A clear understanding of the mechanistic action of rFVIIa in therapy is essential to improve the clinical efficacy of rFVIIa, and to better manage patients and develop a new generation of FVIIa-based therapeutics. We hypothesize that pharmacological concentrations of rFVIIa compete with endogenous protein C for the limited EPCR sites on the endothelium, which diminishes EPCR-dependent APC generation, and thus the down-regulation of the APC anticoagulant pathway. The down-regulation of the APC anticoagulant pathway would enhance FVIIa-induced thrombin generation as factor Va is not readily inhibited by the reduced APC levels. We also hypothesize that EPCR-mediated FVIIa transport and FVIIa-EPCR-mediated barrier protective and anti-inflammatory effects play crucial roles in preventing the joint damage and bone loss in rFVIIa prophylaxis. The following aims will test the above hypotheses. Aim 1: Investigate the importance of FVIIa:EPCR interaction in the hemostatic effect of rFVIIa in treating bleeding disorders and elucidate its mode of action; Aim 2: Characterize FVIIa bio-distribution and tissue retention in prophylaxis and evaluate the contribution of FVIIa-EPCR-mediated hemostatic, barrier protective and anti-inflammatory effects to the prophylactic effect of preventing hemophilic arthropathy; and Aim 3: Elucidate the mechanism by which EPCR ligation with EPCR mAb, in the absence of rFVIIa treatment, provides the vascular barrier protective effect in hemophilia. To perform these studies, we will generate novel mFVIIa variants and unique transgenic mice and employ saphenous vein bleeding, the needle puncture knee injury, and VEGF-and LPS- induced vascular leakage model systems. The outcome of the proposed studies will introduce a paradigm shift in our understanding of how the pharmacological concentration of rFVIIa provides the hemostatic effect in hemophilia patients and patient with other bleeding disorders.

 描述（由申请方提供）：最近的研究表明，凝血因子FVIIa（FVIIa）在血管损伤后与促凝血辅因子组织因子（TF）结合后启动凝血级联反应，也与抗凝辅因子内皮细胞蛋白C受体（EPCR）结合。EPCR通过促进蛋白C的活化在蛋白C抗凝途径中起关键作用。EPCR还促进活化蛋白C（APC）诱导的细胞保护信号传导。在上一个资助周期中进行的研究显示，FVIIa与内皮上的EPCR结合促进FVII/FVIIa从循环转运至血管外部位，与EPCR结合的FVIIa激活蛋白酶激活受体1（PAR 1）介导的细胞信号传导并提供屏障保护作用。发现药理学浓度的rFVIIa可取代EPCR中的内源性蛋白C。rFVIIa通常用于治疗具有FVIII和FIX抑制性抗体的血友病患者。是 也用作儿科和成人患者的紧急止血剂。尽管其广泛和成功的使用，了解的机制rFVIIa的作用在出血性疾病是不完整的。清楚地了解rFVIIa在治疗中的机制作用对于改善rFVIIa的临床疗效、更好地管理患者和开发新一代基于FVIIa的治疗药物至关重要。我们假设rFVIIa的药理浓度与内源性蛋白C竞争内皮上有限的EPCR位点，从而减少EPCR依赖性APC的产生，从而下调APC抗凝途径。APC抗凝剂途径的下调将增强FVIIa诱导的凝血酶生成，因为因子Va不容易被降低的APC水平抑制。我们还假设EPCR介导的FVIIa转运和FVIIa-EPCR介导的屏障保护和抗炎作用在rFVIIa预防中预防关节损伤和骨丢失中起关键作用。以下目标将检验上述假设。目标1：研究FVIIa：EPCR相互作用在rFVIIa治疗出血性疾病的止血作用中的重要性，并阐明其作用模式;目的2：表征预防中的FVIIa生物分布和组织保留，并评价FVIIa-EPCR介导的止血、屏障保护和抗炎作用对预防血友病性关节病的预防作用的贡献;以及目的3：阐明EPCR与EPCR mAb连接在不存在rFVIIa治疗的情况下提供血友病血管屏障保护作用的机制。为了进行这些研究，我们将产生新的mFVIIa变体和独特的转基因小鼠，并采用隐静脉出血，针刺膝关节损伤，VEGF和LPS诱导的血管渗漏模型系统。拟定研究的结果将为我们理解rFVIIa的药理学浓度如何在血友病患者和其他出血性疾病患者中提供止血作用带来范式转变。