Urokinase, Neutrophil Activation and Acute Lung Injury.

描述（由申请人提供）：几乎所有急性肺损伤（ALI）患者都存在凝血和纤溶途径的改变，与尿激酶（uPA）、纤溶酶原激活物抑制剂1 （PAI-1）和玻璃体粘连蛋白循环和肺部浓度升高相关。我们最近的研究结果表明，uPA、PAI-1和玻璃体连接蛋白可以独立于其对凝血和纤溶途径的影响之外，促进ALI的发展：1)通过增强中性粒细胞激活，2)通过减少肺部中性粒细胞的吞噬和清除。我们的假设是：uPA、PAI-1和玻璃连接蛋白通过直接影响肺中中性粒细胞的激活、积累和清除的作用，在决定ALI的发展、持续和严重程度中起主要作用。我们的具体目标是：1)通过识别所涉及的受体和配体，确定uPA和PAI-1增强中性粒细胞活化的机制，研究uPA、PAI-1和玻璃质连接蛋白之间的相互作用如何调节uPA和PAI-1的促炎特性，并确定通过TLR4和整个细菌刺激的中性粒细胞中uPA、PAI-1和玻璃质连接蛋白组合影响的细胞内信号通路；2)通过描述中性粒细胞和巨噬细胞相关PAI-1和玻璃连接蛋白的作用，确定PAI-1和玻璃连接蛋白在中性粒细胞和巨噬细胞上参与调节活中性粒细胞和凋亡中性粒细胞吞噬的受体，确定PAI-1和玻璃连接蛋白调节中性粒细胞吞噬和清除的机制。并描述PAI-1和玻璃质连接蛋白在调节中性粒细胞吞噬过程中受体和配体的表达方面的作用，这些受体和配体包括钙网蛋白（CRT）、CD47、CD31、整合素、mer、axl和LRP，以及影响调理素与PtdSer的结合以及收集素与CRT和CD91的结合；3)通过描述ALI期间PAI-1和vitronectin在调节肺中凋亡中性粒细胞吞噬中的体内作用，以及PAI-1和vitronectin相互作用在ALI严重程度中的重要性，确定PAI-1和vitronectin促进ALI发展和严重程度的机制。拟议的研究不仅应该提高对导致ALI的细胞机制的理解，而且还可能提出旨在降低ALI发病率和/或严重程度的新型治疗干预措施。

DESCRIPTION (provided by applicant): Alterations in coagulation and fibrinolytic pathways, associated with increases in circulating and pulmonary concentrations of urokinase (uPA), plasminogen activator inhibitor 1 (PAI-1), and vitronectin, are present in almost all patients with acute lung injury (ALI). Our recent findings suggest two novel mechanisms through which uPA, PAI-1, and vitronectin can contribute to the development of ALI independently of their effects on coagulation and fibrinolytic pathways: 1) by enhancing neutrophil activation and 2) by decreasing phagocytosis and clearance of neutrophils in the lungs. Our hypothesis is that: uPA, PAI-1, and vitronectin, through actions that directly affect neutrophil activation, accumulation, and clearance in the lungs, are centrally involved in determining the development, perpetuation, and severity of ALI. Our specific aims are: 1) To define the mechanisms through which uPA and PAI-1 potentiate neutrophil activation by identifying the receptors and ligands involved, examining how interactions between uPA, PAI-1, and vitronectin modulate the proinflammatory properties of uPA and PAI-1, and determining the intracellular signaling pathways that are affected by combinations of uPA, PAI-1, and vitronectin in neutrophils stimulated through TLR4 and by whole bacteria; 2) To determine the mechanisms through which PAI-1 and vitronectin modulate phagocytosis and clearance of neutrophils by delineating the roles of neutrophil and macrophage associated PAI-1 and vitronectin, identifying the receptors engaged by PAI-1 and vitronectin on neutrophils and macrophages that participate in modulating phagocytosis of viable and apoptotic neutrophils, and delineating the effects of PAI-1 and vitronectin in modifying the expression of receptors and ligands involved in phagocytosis of neutrophils, including calreticulin (CRT), CD47, CD31, integrins, mer, axl, and LRP, as well as in affecting the binding of opsonins to PtdSer and of collectins to CRT and CD91; and 3) To determine the mechanisms through which PAI-1 and vitronectin contribute to the development and severity of ALI by delineating the in vivo roles of PAI-1 and vitronectin in modulating phagocytosis of apoptotic neutrophils in the lungs during ALI, and examining the importance of interactions between PAI-1 and vitronectin in contributing to the severity of ALI. The proposed studies should not only improve understanding of cellular mechanisms leading to ALI, but also are likely to suggest novel therapeutic interventions aimed at decreasing the incidence and/or severity of ALI.