Inflammation in Vascular Injury and Repair

描述（由申请人提供）：炎症在动脉粥样硬化和再狭窄的血管损伤中起重要作用。血管细胞之间的粘附相互作用协调了这种炎症反应。在该资助期间（6-10年），我们继续关注白细胞整合素Mac-1（aM <$2，CD 11b/CD 18），将这种粘附受体确定为白细胞募集和信号传导的关键分子决定因素。我们的实验室首先报道了Mac-1与其血小板反受体GP Iba之间的相互作用，并且我们现在已经确定了GP Iba识别的分子基础，鉴定了aMl结构域内的P201-K217序列作为GP Iba的结合位点。我们确定，白细胞通过Mac-1参与血小板GP Iba对于血管损伤和修复至关重要，并进行了一项初步研究，表明Mac-1-GP Iba的破坏可预防Dahl盐敏感性转基因大鼠的心肌梗死和心肌存活。此外，Mac-1的信号能力进行了探讨，我们发现，Mac-1招聘IL-1受体样信号级联诱导NF-？B活性。利用差异显示策略，我们克隆了一个新的叉头转录因子，Foxp 1，这是由Mac-1信号调节和控制单核细胞分化。这些观察结果共同揭示了有关白细胞如何在血管损伤部位募集以及整合素如何调节并启动“由外向内”信号的新信息，这表明在体内操纵整合素功能的新机会。这些调查结果是本次更新申请的基础。该建议的中心假设是白细胞Mac-1与血小板GP Iba的相互作用介导血管损伤后白细胞的募集，并且Mac-1促进促炎和促血栓形成信号，其促进动脉粥样硬化形成、斑块破裂、血栓形成和心肌梗死。本提案的总体目标是确定Mac-1介导的炎症在动脉粥样硬化血栓形成中的作用。我们的具体目标是：（1）确定Mac-1-GP Iba之间相互作用的物理决定因素和这种相互作用产生的“由外而内”信号的性质;（2）研究Mac-1-GP Iba在血小板信号传导和血栓形成中的作用;（3）确定破坏Mac-1-GP Iba对斑块破裂、血栓形成和存活的影响。本提案中概述的实验应阐明Mac-1-GP Iba在动脉粥样硬化血栓形成中的作用。由于白细胞-血小板相互作用代表了炎症、动脉粥样硬化和血栓形成之间的重要联系，因此了解这种细胞复合物的分子机制将为制定在动脉粥样硬化的起始、进展和临床并发症中调节血管损伤的策略提供必要的见解。

DESCRIPTION (provided by applicant): Inflammation plays an essential role in vascular injury in atherosclerosis and restenosis. Adhesive interactions between vascular cells orchestrate this inflammatory response. During the period of this grant (years 6-10), we have continued to focus on the leukocyte integrin Mac-1 (aM¿2, CD11b/CD18), identifying this adhesive receptor as a critical molecular determinant of leukocyte recruitment and signaling. Our laboratory first reported the interaction between Mac-1 and its platelet counter-receptor GP Iba and we have now determined the molecular basis of GP Iba recognition, identifying the P201-K217 sequence within the aMl-domain as the binding site for GP Iba. We established that leukocyte engagement of platelet GP Iba via Mac-1 is critical for vascular injury and repair, and have performed a pilot study indicating that disruption of Mac-1-GP Iba prevents myocardial infarction and prolongs survival in Dahl salt-sensitive rats transgenic for human CETP. Further, the signaling capacity of Mac-1 was explored and we found that Mac-1 recruits an IL-1 receptor-like signaling cascade to induce NF-?B activity. Using a differential display strategy, we cloned a novel forkhead transcription factor, Foxp1, which is regulated by Mac-1 signaling and controls monocyte differentiation. Together these observations reveal novel information as to how leukocytes are recruited at sites of vascular injury and how integrins are regulated and initiate "outside-in" signals, suggesting new opportunities for manipulation of integrin function in vivo. These findings are the basis for this renewal application. The central hypotheses of this proposal are that the interaction of leukocyte Mac-1 with platelet GP Iba mediates leukocyte recruitment after vascular injury, and that Mac-1 promotes pro-inflammatory and pro-thrombotic signals that promote atherogenesis, plaque rupture, thrombosis, and myocardial infarction. The overall objective of this proposal is to define the role of Mac-1-mediated inflammation in atherothrombosis. Our specific aims are:(1) To define the physical determinants of the interactions between Mac-1-GP Iba and the nature of "outside-in" signals generated by this interaction; (2) To investigate the role of Mac-1-GP Iba in platelet signaling and thrombosis; and (3) To determine the effect of disrupting Mac-1-GP Iba on plaque rupture, thrombosis, and survival. The experiments outlined in this proposal should clarify the role of Mac-1-GP Iba in atherothrombosis. Because leukocyte-platelet interactions represent an important linkage between inflammation, atherogenesis, and thrombosis, understanding the molecular machinery of this cellular complex will provide insights necessary to develop strategies for modulating vascular injury in the initiation, progression, and clinical complications of atherosclerosis.