Platelet TSP1 Mediates Vascular Disease and pulmonary hypertension in Sickle Cell

描述（由申请人提供）：这是一份K23奖的申请，申请人是血液学家Enrico Novelli博士，医学系终身教职助理教授，匹兹堡大学成人镰状细胞性贫血项目主任。Novelli博士正在将自己确立为良性血液学领域的学术领导者，特别关注镰状细胞病和止血的转化研究。Novelli博士在血液学方面有着丰富的研究经验，并因其SCD研究而成功获得研究奖项。他组建了一支由导师和顾问组成的多学科团队，以指导他的职业生涯走向独立，并协助完成本申请中提出的研究。该补助金将是实现以下职业目标的关键：（1）发展对SCD转化研究至关重要的实验室方法学方面的专业知识;（2）进一步深入了解临床试验设计和生物统计学在人类疾病调查中的基础;（3）成为SCD血管生物学专家。他计划通过完成匹兹堡大学赞助的临床研究理学硕士学位来补充他的研究活动，并参加有关赠款写作和负责任的研究行为的预定培训活动，并参加他感兴趣的领域的国际会议。到K23奖的资助期结束时，他将拥有几篇第一作者的同行评审出版物和大量数据，这些数据将构成RO 1或其他同等资助的核心。本申请的重点是SCD的血管生物学。在SCD中，突变血红蛋白S在脱氧时聚合，驱动红细胞（RBC）依赖性血管闭塞和溶血。这些过程导致血小板和止血剂活化、肺动脉高压和血管疾病。转基因敲除镰状（BERK）小鼠，只表达人类基因？S-球蛋白通过显示降低的NO生物利用度、受损的NO介导的血管反应性和肺动脉高压来模拟人类SCD。最近，血小板发现α-颗粒蛋白血小板反应蛋白-1（TSP 1）通过与细胞表面受体CD 47结合而有效地抑制生理NO信号传导。Novelli博士的初步数据现在表明，SCD患者血浆中的循环TSP 1水平升高。支持这一建议的临床前研究也表明，特异性TSP 1-CD 47配体受体相互作用不仅抑制内皮细胞中的NO信号传导，而且增加了内皮细胞中的NO信号传导。 平滑肌中活性氧（ROS）的产生和内皮素A（ETA）受体的表达，这两种典型的血管收缩和促有丝分裂病理信号传导途径均导致肺动脉高压。使用嵌合体交叉移植系统的大量初步数据证实，CD 47在转基因镰状细胞小鼠PH的发展中是至关重要的。这些发现为格兰特的总体假设提供了信息，即在SCD患者的血小板活化过程中，循环血浆中TSP 1水平的增加，通过与血小板结合， CD 47受体，破坏肺血管内皮NO产生并刺激平滑肌ROS产生和内皮素1信号传导，这导致患有SCD的小鼠模型和人类受试者中的肺动脉高压。该基金还将探索TSP 1-CD 47配体-受体相互作用的治疗性破坏将预防和逆转SCD中的肺动脉高压的假设。（1）第一次检验来自SCD患者血浆中具有SCD TSP 1水平的人类受试者的血浆是否通过抑制NO信号传导和增加ROS和ETA水平而破坏内皮和平滑肌中的血管舒张剂/血管收缩剂平衡;（2）采用独特的突变小鼠模型来确定循环TSP 1和CD 47在SCD相关血管病变和肺动脉高压中的作用，检测阻断TSP 1-CD 47对预防/减轻SCD相关肺动脉高压的疗效;（3）检测几组SCD患者血清TSP 1水平，探讨TSP 1与血小板活化、肺动脉高压及血管病变的关系。这一提议得到了用于调查假设的互补和丰富的工具集的加强，血管医学研究所内的大量资源， 匹兹堡大学致力于血管生物学的研究，并捕捉了Novelli博士的导师在SCD的病理生理学中定义溶血（Mark Gladwin博士的实验室）和TSP 1-CD 47关系作为NO信号传导的上游调节因子（Jeff Isenberg博士的实验室）的开创性工作。因此，该通路的定义将为SCD的血管并发症提供新的治疗靶点。

DESCRIPTION (provided by applicant): This is an application for a K23 award for Dr. Enrico Novelli, a Hematologist, Assistant Professor in the Tenure Stream in the Department of Medicine and Director of the University of Pittsburgh Adult Sickle Cell Anemia Program. Dr. Novelli is establishing himself as an academic leader in the field of benign hematology with a specific focus on translational research in sickle cell disease and hemostasis. Dr. Novelli has prior extensive research experiences in hematology and has been successful in obtaining research awards for his studies on SCD. He has assembled a multidisciplinary team of mentors and advisors to guide his career towards independence and to assist with the completion of the research proposed in this application. This grant will be critical to achieve the following career objectives: (1) to develop expertise in laboratory methodologies crucial to the conduct of translational research in SCD; (2) to gain further in-depth knowledge of clinical trial design and biostatistics fundamental in the investigation of human disease; and (3) to become an expert in the vascular biology of SCD. He plans to complement his research activity with the completion of a Master of Science in Clinical Research sponsored by the University of Pittsburgh, with participation in scheduled training activities on grant writing and responsible conduct of research, and with attendance to international meetings in his areas of interest. By the end of the funding period of this K23 award, he will have several first-authored peer-reviewed publications and a critical mass of data that will form the core of an RO1 or other equivalent grant. The focus of this application is on the vascular biology of SCD. In SCD, mutant hemoglobin S polymerizes when deoxygenated, driving red blood cell (RBC)-dependent vaso-occlusion and hemolysis. These processes lead to platelet and hemostatic activation, pulmonary hypertension and vascular disease. Transgenic-knockout sickle (BERK) mice that express exclusively human ¿- and ?S-globins mimic SCD in humans by displaying reduced NO bioavailability, impaired NO-mediated vascular reactivity and pulmonary hypertension. Recently, the platelet ¿-granule protein thrombospondin-1 (TSP1) was found to potently inhibits physiologic NO signaling, via binding to the cell surface receptor CD47. Preliminary data from Dr. Novelli now demonstrate that circulating TSP1 levels are increased in the plasma of patients with SCD. Preclinical studies supporting this proposal also show that the specific TSP1-CD47 ligand receptor interaction not only inhibits NO signaling in endothelial cells, but also increases reactive oxygen species (ROS) production and endothelin A (ETA) receptor expression in smooth muscle, both canonical vasoconstrictive and mitogenic pathological signaling pathways contributing to pulmonary hypertension. Extensive preliminary data using chimera cross transplantation systems confirm that CD47 is critical in the development of PH in the transgenic sickle cell mouse. These findings inform the grant's overarching hypothesis that during platelet activation in patients with SCD, increases in circulating plasma levels of TSP1, via binding to the CD47 receptor, disrupt pulmonary vascular endothelial NO production and stimulate smooth muscle ROS production and endothelin 1 signaling, which lead to pulmonary hypertension in murine models and human subjects with SCD. This grant will also explore the hypothesis that therapeutic disruption of the TSP1-CD47 ligand-receptor interaction will both prevent and reverse pulmonary hypertension in SCD. This hypothesis will be tested via the following aims: (1) to examine for the first time whether plasma from human subjects with SCD TSP1 levels in the plasma of patients with SCD disrupt the vasodilator/vasoconstrictor balance in endothelium and smooth muscle by inhibition of NO signaling and increasing ROS and ETA levels; (2) to employ unique mutant murine models to determine the role of circulating TSP1 and CD47 in SCD-associated vasculopathy and pulmonary hypertension, and test the therapeutic efficacy of blocking TSP1-CD47 to prevent/mitigate SCD-based pulmonary hypertension; and (3) to test TSP1 levels in several large cohorts of patients with SCD and explore the correlation of TSP1 with platelet activation, pulmonary hypertension and vascular disease. This proposal is strengthened by the complementary and rich tool set used to investigate the hypothesis, the vast resources available within the Vascular Medicine Institute, a state of the art facility within the University of Pittsburgh devoted to the study of vascular biology, and captures the pioneering work of Dr. Novelli's mentors in defining hemolysis in the pathophysiology of SCD (Dr. Mark Gladwin's lab) and the TSP1-CD47 nexus as an upstream regulator of NO signaling (Dr. Jeff Isenberg's lab). Definition of this pathway will therefore present a novel therapeutic target for the vascular complications of SCD.