Regulation of lung epithelial injury by plasminogen activator inhibitor-1

描述（由申请人提供）：我们的假设是烟草烟雾（TS）暴露（TSE）通过新发现的调节途径促进气道上皮细胞凋亡，该途径涉及通过p53转录后稳定PAI-1 mRNA诱导纤溶酶原激活物抑制剂(PAI) -1。我们的初步数据支持了这一假设，并扩展了成熟的文献体系，这些文献表明上皮细胞损伤和纤溶途径参与了多种肺损伤的发病机制，包括由TSE引起的COPD和气道重塑。虽然先前的研究提示p53蛋白参与气道上皮细胞损伤，并强烈提示PAI-1在气道反应性增加的发病机制中起关键作用，但PAI-1在tse诱导的气道损伤中的作用目前尚不清楚。我们的目的是确定PAI-1的表达如何受到tse诱导的p53的控制，并阐明该途径影响气道上皮细胞凋亡的机制。然后，我们将阻断TSE介导的PAI-1诱导，以逆转由TSE引起的气道和肺泡上皮细胞凋亡。我们将采用体外和体内两种方法来实现这些目标。我们将在体外确定人小气道上皮或肺泡型（AT） II细胞原代培养物对TSE的反应，并在平行研究中测试反应的特异性，在平行研究中，我们将测试从小鼠肺分离的原代ATII细胞的反应。接下来，我们将在WT、p53-/-和PAI-1-/-小鼠中测定TSE的作用，以阐明p53介导的PAI-1表达对体内肺上皮细胞凋亡的影响。我们的具体目标是：1。探讨p53诱导PAI-1及抑制PAI-1表达调控体外气道和肺泡上皮细胞凋亡的机制。2. 探讨p53诱导的PAI-1及抑制PAI-1表达对tse诱导的肺损伤LEC凋亡的影响。这些研究解决了目前关于纤维蛋白溶解系统如何通过PAI-1 mRNA与p53的相互作用调节tse诱导的气道损伤的知识中的一个关键空白。这个项目将我们实验室正在进行的翻译工作扩展到一个重要的临床新领域。我们将利用我们在转录后机制领域的专业知识，阐明p53介导的气道上皮PAI-1表达如何调节上皮细胞凋亡，而上皮细胞凋亡是TSE诱导的气道重塑的特征。这些研究将加速新的治疗干预措施的发展，以减轻肺上皮损伤。

DESCRIPTION (provided by applicant): Our hypothesis is that tobacco smoke (TS) exposure (TSE) promotes apoptosis of airway epithelial cells through a newly identified regulatory pathway that involves induction of plasminogen activator inhibitor (PAI) -1 through posttranscriptional stabilization of PAI-1 mRNA by p53. This hypothesis is supported by our preliminary data and extends a mature body of literature that implicates epithelial cell injury and the participation of the fibrinolytic pathway in the pathogenesis of a wide range of lung injuries, including COPD and airway remodeling induced by TSE. While prior studies implicate p53 protein in airway epithelial cell damage and strongly suggest that the PAI-1 plays a key role in the pathogenesis of increased airway reactivity, the role of PAI-1 in TSE-induced airway injury remains unclear at the present time. Our objectives are to determine how PAI-1 expression is controlled by TSE-induced p53 and elucidate the mechanism by which this pathway affects airway epithelial cell apoptosis. We will then block TSE-mediated induction of PAI-1 to reverse airway and alveolar epithelial cell apoptosis due to TSE. We will apply both in vitro and in vivo approaches to achieve these objectives. We will determine the responses of primary cultures of human small airway epithelial or alveolar type (AT) II cells to TSE in vitro and test the specificity of the responses in parallel studies in which we will test the responses of primary ATII cells isolated from mouse lungs. We will next determine the effects of TSE in WT, p53-/- and PAI-1-/- mice to elucidate the effect of p53-mediated expression of PAI-1 on lung epithelial cell apoptosis in vivo. Our specific aims are: 1. To determine the mechanism by which p53-induced PAI-1, and inhibition of PAI-1 expression, modulate airway and alveolar epithelial cell apoptosis in vitro. 2. To determine how p53-induced PAI-1 and inhibition of PAI-1 expression contribute to LEC apoptosis during TSE-induced lung injury in vivo. These studies address a critical gap in current knowledge about how the fibrinolytic system regulates TSE-induced airway damage via interaction of PAI-1 mRNA with p53. This project extends the ongoing translational work of our laboratory to a clinically important new area. We will deploy our expertise in the area of posttranscriptional mechanisms to now elucidate how p53-mediated PAI-1 expression by the airway epithelium regulates epithelial apoptosis that characterizes airway remodeling induced by TSE. These studies will accelerate the development of novel therapeutic interventions to mitigate lung epithelial injury. PUBLIC HEALTH RELEVANCE: Tobacco smoke exposure (TSE) damages the airway lining otherwise called the lung epithelium. TSE-induced damage to the lining of the lungs characterizes chronic obstructive lung disease (COPD) which is the fourth leading cause of death in the United States. Our findings and those of the literature suggest that TSE-induced airway injury involves programmed airway epithelial cell death, airway inflammation and abnormal fibrin turnover. In this project, we will determine how p53, a protein causing epithelial cell death, regulates PAI-1, an inhibitor of the blood clot dissolution system, to influence the viability of the airway epithelium. These studies will enable us to understand the role of newly identified interactions between p53 and PAI-1 in the pathogenesis of lung epithelial cell injury and airway remodeling and will accelerate the development of new strategies to protect the airways against TSE-mediated damage.