Mechanisms of Prostacyclin-Mediated Lung Endothelial Barrier Protection

描述（由申请人提供）：开发治疗急性肺损伤（ALI）和成人呼吸窘迫综合征（ARDS）的有效疗法仍然是一项具有挑战性的任务。许多用于测试新型保护剂的实验模型在ALI诱导期间采用预防性或并发治疗，而治疗后则代表更多临床相关的干预。这种给药时间上的差异可能对治疗效率和特定分子机制的激活产生巨大影响，这些机制指导持续损伤的解决，而不是通过药物预处理阻断ALI的发作。本研究将填补这一空白，并探讨fda批准的前列环素（PC）类似物伊洛前列素在体外和体内感染性ALI模型中的后处理效果。炎症和内皮细胞（EC）通透性增加在ALI的病理生理中起主要作用。在本提案的前一个周期中，我们首次表征了pc介导的呼吸机诱导肺损伤无菌模型中保护的分子机制。我们的初步研究表明，PC预处理对lps诱导的肺部炎症和血管泄漏具有有效的保护作用。本研究拟探讨PC后处理对革兰氏阳性热灭活金黄色葡萄球菌（HKSA）致脓毒性ALI的细胞培养及动物模型的影响。我们假设Rap1 GTPase的信号传导通过促进EC屏障修复和抑制炎症内皮活化在pc诱导的ALI消退加速中起双重作用。Aim-1将评估PC后处理的效果，并确定Rap1在HKSA挑战的EC中加速屏障恢复的作用。Aim-2将定义Rap1下游参与EC屏障恢复的分子机制。我们将研究Rap1效应物KRIT1和RIAM在增强EC粘附结构和外周细胞骨架中的作用，这是重建EC屏障所必需的。Aim-3将研究PC后处理刺激Rap1、KRIT1和RIAM在下调hksa诱导的肺EC激活中的作用。Aim-4将通过“功能丧失”和“功能获得”分子方法和小鼠遗传模型阐明Rap1、KRIT1和Riam在pc促进的ALI体内恢复中的具体作用。这些研究将描述新的保护机制，并为未来治疗确定新的蛋白靶点，旨在预防与急性肺损伤相关的肺血管屏障功能障碍。

DESCRIPTION (provided by applicant): Development of effective therapies for treatment of acute lung injury (ALI) and adult respiratory distress syndrome (ARDS) remains a challenging task. Many experimental models for testing of novel protective agents utilize preventive or concurrent treatment during ALI induction, while post-treatment represents more clinically relevant intervention. Such differences in the timing of drug administration may have dramatic impact on the efficiency of treatment and activation of specific molecular mechanisms directing resolution of ongoing injury in contrast to blocking onset of ALI by drug pretreatment. This proposal will fill this void and explore effects of post-treatment with FDA-approved prostacyclin (PC) analog iloprost in the in vitro and in vivo septic ALI models. Inflammation and increased endothelial cell (EC) permeability play a major role in the pathophysiology of ALI. During the previous cycle of this proposal, we characterized for the first time the molecular mechanisms of PC-mediated protection in aseptic model of ventilator induced lung injury. Our preliminary studies suggest potent protective effects of PC pretreatment against LPS-induced lung inflammation and vascular leak. This proposal will investigate effects of PC post-treatment in cell culture and animal models of septic ALI caused by Gram-positive heat-inactivated Staphylococcus Aureus bacteria (HKSA). We hypothesize that signaling by Rap1 GTPase plays a dual role in PC-induced acceleration of ALI resolution via promotion of EC barrier repair and suppression of inflammatory endothelial activation. Aim-1 will evaluate effects of PC post-treatment and define a role of Rap1 in acceleration of barrier recovery in HKSA challenged EC. Aim-2 will define molecular mechanisms downstream of Rap1 involved in EC barrier recovery. We will study a role of Rap1 effectors KRIT1 and RIAM in enhancement of EC adhesive structures and peripheral cytoskeleton essential for re-establishment of EC barrier. Aim-3 will study a role of Rap1, KRIT1 and RIAM stimulation by PC post-treatment in downregulation of HKSA-induced pulmonary EC activation. Aim-4 will elucidate specific role of Rap1, KRIT1 and Riam in PC-facilitated ALI recovery in vivo using "loss of function" and "gain of function" molecular approaches and mouse genetic models. These studies will characterize novel protective mechanisms and identify new protein targets for future therapies aimed at prevention of the pulmonary vascular barrier dysfunction associated with acute lung injury.