Role Of p120 Catenin In Sepsis-Induced Lung Injury

描述(申请人提供)：细菌内毒素(脂多糖)可引发全身性炎症反应，继而导致多器官功能障碍综合征。内毒素与Toll样受体4(TLR4)结合可诱导丝裂原活化蛋白激酶(MAPK)和核因子B(NF-B)活化，从而产生促炎细胞因子。当这种产生变得不受控制和过度时，就会导致感染性休克的发生。P120-catenin是内皮细胞和其他极化黏附细胞中黏附连接的一种成分，最近被认为与炎症的内在调节有关。P120-连环蛋白缺失的表皮细胞表现出较高的核因子-B活性和促炎核因子-(B靶标)。在初步实验中，我们进行了耐人寻味的观察，发现带有特定siRNA的肺血管中p120的缺失使小鼠对内毒素高度敏感，这表明p120是宿主对脓毒症反应的关键元件。我们的支持数据进一步表明，在脂多糖攻击后，小鼠肺组织中p120-catenin的表达迅速减少。此外，肺血管内皮细胞和培养的肺微血管内皮细胞中p120-catenin的缺失显著增加了内毒素诱导的细胞间黏附分子-1(ICAM-1)的表达、中性粒细胞的黏附，以及通过激活NF-B和MAPK信号通路使中性粒细胞跨内皮细胞迁移。总而言之，这些数据表明，p120-catenin有助于抑制内毒素诱导的肺部炎症反应。本研究的目的是明确p120-catenin的抗炎作用，确定内毒素诱导p120-catenin降解的机制，并探讨p120-catenin干扰TLR4激活的信号通路减轻肺炎性损伤的可能性。该提案将针对以下具体目标：1.确定内毒素诱导的肺损伤时肺内皮细胞p120-catenin表达的调节机制。在这里，我们将剖析导致内毒素攻击后肺微血管中p120丢失的信号通路。2.明确内皮细胞p120-连环蛋白表达在内毒素诱导的肺炎性损伤中的调节作用。3.明确内皮细胞p120调节TLR4信号介导的肺炎症的信号通路。识别p120-连环蛋白激活的通路调节脂多糖诱导的脓毒症将在设计治疗或预防急性肺损伤的治疗策略方面具有重要意义。 公共卫生相关性：由广泛的细菌感染引起的急性肺损伤是一种严重的危及生命的疾病，需要在医院重症监护病房使用机械呼吸机和其他支持性护理。我们已经证明，肺中的蛋白p120-catenin在预防引起急性肺损伤的严重肺部炎症方面起着至关重要的作用。本研究的目的是明确p120-catenin调节肺部炎症的基本分子机制，以设计新的有效的治疗或预防急性肺损伤的策略。

DESCRIPTION (provided by applicant): The bacterial endotoxin (lipopolysaccharide, LPS) can trigger systemic hyper-inflammatory response that subsequently leads to multiple organ dysfunction syndrome. LPS binding to toll-like receptor 4 (TLR4) induces the activation of mitogen-activated protein kinase (MAPK) and nuclear factor (B (NF-(B) resulting in production of pro-inflammatory cytokines. When this production becomes uncontrolled and excessive, it leads to the development of septic shock. p120-catenin, a component of adherens junctions in endothelial cells and other polarized adherent cells, has recently been implicated in the intrinsic regulation of inflammation. p120-catenin null epidermal cells exhibited increased activity of NF-(B and proinflammatory NF-(B targets. In preliminary experiments, we made the intriguing observation that deletion of p120 in the lung vasculature with specific siRNA rendered the mice highly susceptible to LPS, suggesting that p120 is a crucial element of the host response to sepsis. Our supporting data further demonstrate that p120-catenin expression in the mouse lung is rapidly reduced after LPS challenge. Also, deletion of p120-catenin in pulmonary vasculature endothelium and cultured pulmonary microvascular endothelial cells significantly increased LPS-induced expression of intercellular adhesion molecule-1 (ICAM-1), neutrophil adhesion, and transendothelial neutrophil migration via activation of NF-(B and MAPK signaling. Collectively, these data suggest that p120-catenin serves to dampen the LPS-induced inflammatory response in lungs. The objectives of the proposed studies are to define the anti-inflammatory role of p120-catenin, determine the mechanism of p120-catenin degradation induced by LPS, and to explore the possibility that p120-catenin interferes with the TLR4-activated signaling pathway to mitigate lung inflammatory injury. The proposal will address the following Specific Aims: 1. To determine the mechanisms of regulation of pulmonary endothelial p120-catenin expression in response to LPS-induced lung injury. Here we will dissect the signaling pathways that cause the loss of p120 in the pulmonary microvasculature following LPS challenge. 2. To define the role of endothelial p120-catenin expression in the regulation of LPS-induced lung inflammatory injury. 3. To identify the signaling pathways by which endothelial p120 regulates TLR4 signaling-mediated lung inflammation. The identification of p120-catenin-activated pathways modulating LPS-induced sepsis will be of great interest in the design of therapeutic strategies for the treatment or prevention of acute lung injury. PUBLIC HEALTH RELEVANCE: Acute lung injury caused by widespread bacterial infection is a severe and life threatening condition that requires a mechanical breathing machine and other supportive care in hospital intensive care units. We have shown that protein p120-catenin in the lung plays an essential role in preventing severe lung inflammation that causes acute lung injury. The purpose of this research is to define the basic molecular mechanisms by which p120-catenin regulates lung inflammation in order to design new and effective strategies for the treatment or prevention of acute lung injury.