Pathophysiology of Alveolar Epithelial Lung Injury

描述(由申请人提供)： 本项目拨款申请的基础假设是肺泡上皮细胞屏障的损伤和恢复对决定急性呼吸窘迫综合征(ARDS)患者的预后至关重要。在这些患者中，肺泡上皮的不同区域暴露于低氧、高氧、拉伸和机械剪切，所有这些都可能导致肺泡上皮细胞的损伤。我们召集了一个由高级研究人员组成的高度互动的小组，通过五个相关的项目来研究这些模型中的肺泡上皮细胞损伤。在项目1中，我们将确定缺氧通过磷酸化-内吞和泛素化-Na+泵降解抑制Na，K-ATPase，从而损害肺液清除的机制。在项目2中，我们将通过改变组成细胞骨架的主要蛋白质中间丝的结构和功能来确定肺泡上皮细胞暴露在循环拉伸或循环剪切应力下导致损伤的机制。在项目#3中，我们将确定细胞表面的层粘连蛋白和整合素在周期性拉伸过程中作为机械信号分子在肺泡上皮细胞中传递MAPK信号的机制。在项目#4中，我们将研究受体依赖和线粒体依赖的肺泡上皮细胞凋亡在高氧暴露后肺损伤发展中的作用。在项目#5中，我们将确定将上皮细胞暴露于周期性拉伸促进基因转移到肺泡上皮的机制。每个项目都进行了协作研究，初步结果支持这一建议的可行性。该计划项目集中了聚集的研究人员的多学科专业知识，以阐明在临床相关模型中导致肺上皮细胞损伤的机制。这些项目在概念上和实践上都是互动的，项目的总和大于其各部分的总和。这些收集的数据将提供主要肺泡上皮细胞蛋白(Na，K-ATPase和中间丝约占总肺泡上皮细胞蛋白的60%)调节的合成图像，确定上皮细胞凋亡在肺损伤发病机制中的作用，开发新的非病毒向肺传递基因的策略，并确定细胞外基质在肺泡上皮细胞机械信号转导中的作用。从这些研究产生的数据中获得的见解将为开发新的治疗策略来治疗肺损伤患者提供新的分子靶点。

DESCRIPTION (provided by applicant): This Program Project Grant application is founded on the hypothesis that the injury and recovery of the alveolar epithelial cell barrier are of crucial importance in determining the outcome of patients with the acute respiratory distress syndrome (ARDS). In these patients, different regions of the alveolar epithelium are exposed to hypoxia, hyperoxia, stretch and mechanical shear, all of which may contribute to alveolar epithelial cell injury. We have assembled a highly interactive group of senior investigators to study alveolar epithelial cell injury in these models via five interrelated projects. In Project # 1 we will determine the mechanisms by which hypoxia inhibits the Na,K-ATPase via phosphorylation-endocytosis and ubiquitination-degradation of the Na+ pump resulting in impaired lung liquid clearance. In Project # 2 we will determine the mechanisms by which exposure of alveolar epithelial cells to cyclic stretch or cyclic shear stress causes injury by altering the structure and function of intermediate filaments, the major protein comprising the cell cytoskeleton. In Project # 3 we will determine the mechanisms by which laminins and integrins at the cell surface serve as mechanosignaling molecules transducing MAPK signals in alveolar epithelial cells during cyclic stretch. In Project #4 we will investigate the role of receptor-dependent and mitochondrial-dependent alveolar epithelial apoptosis in the development of lung injury following exposure to hyperoxia. In Project # 5 we will determine the mechanisms by which exposure of epithelial cells to cyclic stretch enhances gene transfer to the alveolar epithelium. Collaborative studies have been conducted for each of the projects and the preliminary results support the feasibility of this proposal. This Program Project focuses the multidisciplinary expertise of the assembled investigators on the elucidation of mechanisms contributing to lung epithelial cell injury in clinically relevant models. These projects are interactive conceptually and pragmatically, where the aggregate of the projects is greater than the sum of its parts. The collective data will provide a composite picture of the regulation of the major alveolar epithelial cell proteins (the Na,K-ATPase and intermediate filaments represent about 60% of total alveolar epithelial cell proteins), determine the role of epithelial apoptosis in the pathogenesis of lung injury, develop novel strategies for the non-viral delivery of genes to the lung and define the role of the extracellular matrix in mechanosignaling in the alveolar epithelium. The insights gained from the data generated from these studies will provide novel molecular targets for the development of new therapeutic strategies to treat patients with lung injury.