Hypoxia-induced Endothelial Barrier Dysfunction

描述（由申请人提供）：非心源性肺水肿是肺内科常见的疾病，由内皮屏障功能障碍引起。现在认识到，这种功能障碍可能是由程序化细胞信号传导引发的，而不是血管屏障的非特异性破坏。由于内皮屏障是已知的改变暴露于缺氧导致肺水肿，我们已经利用大鼠肺动脉微血管内皮细胞（EC）单层培养模型来研究缺氧对EC屏障功能的影响。初步研究提出了这样的假设：缺氧暴露通过涉及MK 2和HSP 27激活的p38 MAP激酶途径启动细胞信号传导，从而导致肌动蛋白细胞骨架和hic-5重新分布。这些信号事件与EC单层的生物力学“束缚”和“刚度”的改变以及增强的渗透性相关。“栓系”可能受p38 MAP激酶途径调节，而“刚度”受Rho/Rho激酶和肌球蛋白轻链磷酸化调节。我们计划在本提案中更彻底地研究这些反应，在大鼠肺动脉微血管EC单层，并在类似的细胞从人类肺微血管进行验证性研究。此外，我们将研究这些信号通路在小鼠体内使用药理学抑制剂，以及小鼠中的MK2，在p38通路中的关键激酶的表达，已被“敲除”。具体而言，我们计划：目标1：定义对介导暴露于缺氧的内皮细胞单层中细胞骨架变化重要的信号传导途径;目的2：确定生物力学终点“刚度”和“束缚”（随暴露于缺氧而增加）与内皮屏障功能的生理决定因素的相关性;目的3：评价导致体内缺氧中肺内皮通透性增加的信号传导事件。这项研究的结果，预计将进一步我们了解的机制，参与发展的内皮屏障功能障碍，一般，并建议治疗肺水肿的目标。

DESCRIPTION (provided by applicant): Non-cardiac pulmonary edema is a frequent affliction in pulmonary medicine and is caused by endothelial barrier dysfunction. It is now recognized that this dysfunction may be initiated by programmed cell signaling as opposed to non-specific disruption of the vascular barrier. Since the endothelial barrier is known to be altered by exposure to hypoxia leading to pulmonary edema, we have utilized a rat pulmonary artery microvascular endothelial cell (EC) monolayer culture model to study the effects of hypoxia on EC barrier function. Preliminary studies have led to the hypothesis that exposure to hypoxia initiates cell signaling through the p38 MAP kinase pathway involving MK2 and HSP27 activation that leads to actin cytoskeleton and hic-5 redistribution. These signaling events are associated with an alteration in biomechanical "tethering" and "stiffness" and enhanced permeability of the EC monolayer. "Tethering" may be regulated by the p38 MAP kinase pathway while "stiffness" is regulated by Rho/Rho kinase and myosin light chain phosphorylation. We plan in the present proposal to study these responses more thoroughly in the rat pulmonary artery microvascular EC monolayer and to perform confirmatory studies in similar cells from human pulmonary microvasculature. In addition, we will investigate these signaling pathways in mice in vivo using pharmacological inhibitors, as well as mice in which the expression of MK2, a key kinase in the p38 pathway, has been "knocked-out". Specifically, we plan to: Aim 1: Define signaling pathways important for mediating cytoskeletal changes in endothelial cell monolayers exposed to hypoxia; Aim 2: Determine the relevance of the biomechanical endpoints "stiffness" and "tethering", which increase with exposure to hypoxia, to physiological determinants of endothelial barrier function; and Aim 3: Evaluate the signaling events that lead to increased pulmonary endothelial permeability in hypoxia in vivo. The findings of this study are expected to further our understanding of mechanisms involved in the development of endothelial barrier dysfunction, in general, and to suggest targets for treatment of pulmonary edema.