Oxidant Regulation of Proteolysis in Acute Lung Injury

描述（由申请方提供）：急性肺损伤是危重患者呼吸衰竭的主要原因，其特征为嗜中性粒细胞为主的炎症反应。炎症损害气道上皮和支持结缔组织，导致微血管渗漏，然后肺组织纤维化，这是该疾病的临床标志。因此，中性粒细胞和上皮细胞之间的相互作用的调节可能控制组织修复的基本机制，并且破坏调节可能导致肺损伤。最近的研究表明，在急性肺损伤模型中，中性粒细胞的募集关键取决于基质金属蛋白酶（MMPs）。MMPs通过在体外和体内肺损伤模型中从上皮细胞释放有效的化学引诱物来募集中性粒细胞。中性粒细胞是活性中间体的主要来源，氧化剂是体外MMPs的有效激活剂。此外，许多证据表明，当人类发生急性肺损伤时，氧化应激会增加。这些观察结果表明，活性中间体可能有助于中性粒细胞的招聘，MMP激活，肺损伤的发病机制，通过多种机制。本提案的总体目标是检验肺的炎性细胞产生的反应性物质对于调节MMP活性和介导急性肺损伤至关重要的假设。我们将探讨这个问题，通过研究MMP的氧化和激活在体外，分析MMP在人肺样本的氧化损伤的证据，并使用小鼠模型来研究急性肺损伤中的氧化损伤和MMP激活。这些补充研究将使我们能够确定我们在体外发现的MMP激活机制是否也在体内起作用。

DESCRIPTION (provided by applicant): Acute lung injury is a major cause of respiratory failure in critically ill patients, and it is characterized by a neutrophil-dominated inflammatory response. Inflammation damages the airway epithelium and supporting connective tissue, leading to microvascular leak and then lung tissue fibrosis, the clinical hallmarks of the disorder. Thus, regulation of interactions between neutrophils and epithelial cells likely control fundamental mechanisms of tissue repair, and disrupted regulation may lead to lung injury. Recent studies demonstrate that neutrophil recruitment in a model of acute lung injury depends critically on matrix metalloproteinases (MMPs). MMPs recruit neutrophils by releasing potent chemoattractants from epithelial cells in vitro and in lung injury models in vivo. Neutrophils are a major source of reactive intermediates, and oxidants are potent activators of MMPs in vitro. Also, many lines of evidence suggest that oxidative stress increases when humans develop acute lung injury. These observations indicate that reactive intermediates may contribute to neutrophil recruitment, MMP activation, and the pathogenesis of lung injury by a variety of mechanisms. The overall goal of this proposal is to test the hypothesis that reactive species generated by inflammatory cells of the lung are critical for regulating MMP activity and mediating acute lung injury. We will approach this issue by investigating MMP oxidation and activation in vitro, analyzing MMPs in human lung samples for evidence of oxidative damage, and using mouse models to investigate oxidative damage and MMP activation in acute lung injury. These complementary studies will enable us to determine whether mechanisms of MMP activation that we uncover in vitro also operate in vivo.