Caveolin-1 and NO Regulate PMN-mediated Increases in Vascular Permeability

通过ICAM-1激活附着在内皮细胞上的多形核白细胞（PMNs），诱导肺血管内皮通透性增加，导致富蛋白肺水肿形成和急性肺损伤。然而，pmn诱导内皮细胞通透性增加的机制尚不完全清楚。我们的支持数据表明，增加的小泡介导的白蛋白的跨细胞转运可能有助于增加内皮通透性，因此可能是导致肺微血管渗漏的一个因素。在这个更新的应用中，我们将讨论PMNs在诱导小囊泡依赖性白蛋白胞吞激活和促进水肿形成中的作用。这些研究将验证以下假设：(i) PMNs的fMLP激活刺激内皮细胞中小泡介导的白蛋白胞吞作用，并介导内皮通透性增加和肺损伤；（ii）内皮细胞中PMN活化Src激酶通过pi3激酶和Akt信号调节enos介导的NO产生，PMN-内皮相互作用产生的NO调节跨细胞和连接通透性途径，增加肺微血管通透性。我们将描述负责内皮通透性激活的信号通路及其在肺水肿形成机制中的后果。使用的方法包括敲除小鼠，sirna诱导的蛋白表达抑制，跨细胞和细胞旁通路的内皮通透性评估，活内皮细胞中小泡介导的运输的成像分析，以及相关信号通路的生化评估。对完整小鼠肺的研究将辅以对小鼠肺内皮细胞的研究，以提供对pmn激活的内皮通透性增加的信号传导基础的更详细和机制的理解。这些研究将为PMN活化诱导肺内皮通透性增加的机制提供一个新的视角，并希望发现新的分子靶点和更好的设计策略，以治疗富含蛋白质的肺水肿和急性肺损伤。

Increased lung vascular endothelial permeability induced by activation of polymorphonuclear leukocytes (PMNs) adherent to endothelial cells via ICAM-1 leads to protein-rich pulmonary edema formation and acute lung injury. However, the mechanisms responsible for PMN-induced increased endothelial permeability are incompletely understood. Our supporting data demonstrate that increased caveolae- mediated transcellular transport of albumin may contribute to increased endothelial permeability, and thus may be a factor leading to leaky lung microvessels. In this renewal application, we will address the role of PMNs in inducing the activation of caveolae-dependent transcytosis of albumin and promoting edema formation. The studies will test the hypotheses that (i) fMLP activation of PMNs stimulates caveolae- mediated albumin transcytosis in endothelial cells and mediates the increase in endothelial permeability and lung injury, and (ii) PMN activation of Src kinase in endothelial cells regulates eNOS-mediated NO production via PI3-kinase and Akt signaling and that the NO derived from PMN-endothelial interaction regulates transcellular and junctional permeability pathways to increase lung microvessel permeability. We will delineate the signaling pathways responsible for the activation of endothelial permeability and its consequences in the mechanism of lung edema formation. The approaches to be used include knockout mice, siRNA-induced suppression of protein expression, endothelial permeability assessment of transcellular and paracellular pathways, imaging analysis of caveolae mediated trafficking in live endothelial cells, and biochemical assessments of relevant signaling pathways. Studies in intact mouse lungs will be complemented by studies utilizing mouse lung endothelial cells to provide a more detailed and mechanistic understanding of the signaling basis of PMN-activated increase in endothelial permeability. These studies will provide a novel perspective into the mechanism of increased transendothelial permeability in lungs induced by PMN activation, with the hope of identifying novel molecular targets and better designing strategies directed at treating protein-rich pulmonary edemagenesis and acute lung injury.