The role of HMGB-1 and innate immunity in promoting angiogenesis after ischemia

描述（由申请人提供）：本提案描述了Ulka Sachdev博士的职业目标和研究计划，他是匹兹堡大学血管外科系的外科助理教授。Sachdev博士在纽约西奈山医学院完成了普通外科和血管外科培训，并在她的培训和早期教师生涯中一直积极从事基础科学研究。她的目标是成为一名独立资助的外科医生-科学家，并最终进行转化研究以帮助患者。这项提案是对缺血诱导的血管生成以及HMGB-1在该现象中的作用进行了四年研究的结果。外周动脉疾病是导致严重功能障碍和发病的原因。随着腿部动脉闭塞性疾病的严重程度增加，可能发生严重肢体缺血，导致高达40%的不可重建疾病患者截肢。需要进一步的研究来评估在肢体缺血的情况下促进血管生成的机制，以优化不能接受手术血运重建的患者的药物治疗。炎症是血管生成的一个组成部分，最近的证据表明，已知在介导炎症的全身效应中起作用的核蛋白HMGB-1也可能是促血管生成的。HMGB-1激活先天免疫受体，包括Toll样受体（TLR）2和4，以及晚期糖基化终产物受体（TLR）。本研究的目的是评估HMGB-1和TLR在促进缺血后血管生成中的作用。此外，Sachdev博士已经表明，HMGB-1增强内皮细胞（EC）管形成，这是一种血管生成表型，当与缺氧刺激结合时增加EC增殖，并且可能由自噬介导。她还表明，HMGB-1的抗体阻断内皮管的形成，并导致更大的肌肉坏死时，已经经历了股动脉结扎，这是一个公认的模型血管生成的小鼠。自噬的抑制也破坏了内皮管的形成。TLR 4缺陷的小鼠也表现出比对照组更大的肌肉坏死面积，TLR 2KO小鼠也是如此。最后，她已经表明，与含氧量正常的肌细胞相比，缺血性肌细胞显示HMGB-1从细胞核中丢失，这表明组织缺血可能导致HMGB-1释放到周围环境中，使其可用于介导血管生成事件。该提案有三个主要目的，旨在了解HMGB-1对体外血管细胞和体内缺血诱导的血管生成的影响。第一个目的是确定EC血管生成行为中自噬和HMGB 1释放之间的时间关系。第二个目的是确定HMGB-1和自噬在体内骨骼肌血管生成中的功能。第三个目的是确定TLR在介导HMGB 1的血管生成作用中的作用。

DESCRIPTION (provided by applicant): This proposal describes the career goals and research plan for Dr. Ulka Sachdev, who is an Assistant Professor of Surgery in the Division of Vascular Surgery at the University of Pittsburgh. Dr. Sachdev completed her General Surgery and Vascular Surgery training at Mount Sinai School of Medicine in New York, and has been active in basic science research throughout her training and early faculty career. Her goal is to become an independently funded surgeon-scientist, and eventually perform translational research to assist patients. This proposal culminates from four years of research on ischemia-induced angiogenesis, and the role of HMGB-1 within that phenomenon. Peripheral artery disease is a cause of significant functional disability and morbidity. With increasing severity of arterial occlusive disease in the leg, critical limb ischemia can occur resulting in amputation in up to 40% of patients with non-reconstructable disease. Further study is required to evaluate the mechanisms that promote angiogenesis in the setting of limb ischemia, in order to optimize medical treatments for patients who can not undergo surgical revascularization. Inflammation is a component of angiogenesis, and recent evidence suggests that the nuclear protein HMGB-1 which is known to play a role in mediating systemic effects of inflammation, may also be pro-angiogenic. HMGB-1 activates receptors of innate immunity, including Toll-like Receptors (TLR) 2 and 4, as well as the Receptor for Advanced Glycation End-products (RAGE). The purpose of this proposal is to evaluate the role of HMGB-1 and TLRs in promoting angiogenesis in response to ischemia. Preliminarily, Dr. Sachdev has shown that HMGB-1 enhances endothelial cell (EC) tube formation, which is an angiogenic phenotype, increases EC proliferation when coupled with hypoxic stimulus, and may be mediated by autophagy. She has also shown that antibody to HMGB-1 blocks endothelial tube formation, and results in greater muscle necrosis when given to mice that have undergone femoral artery ligation, which is a recognized model of angiogenesis. Inhibition of autophagy also disrupts endothelial tube formation. Mice deficient in TLR4 also demonstrate greater areas of muscle necrosis than controls, as do TLR2KO mice. Finally, she has shown that ischemic myocytes demonstrate loss of HMGB-1 from nuclei compared to normoxic myocytes, suggesting that tissue ischemia may lead to release of HMGB-1 into the surrounding milieu, rendering it available to mediate angiogenic events. There are three main aims of this proposal, directed at understanding the effect of HMGB-1 on both vascular cells in vitro, and ischemia-induced angiogenesis in vivo. The first aim is to determine the temporal relationship between autophagy and HMGB1 release during EC angiogenic behavior. The second aim is to determine the function of HMGB-1 and autophagy in skeletal muscle angiogenesis in vivo. The third aim is to identify a role for the TLRs in mediating the angiogenic actions of HMGB1.