MECHANISMS OF PAI1 REGULATION BY LUNG MATRIX MOLECULES

肺纤维化是一种常见的和毁灭性的并发症急性 或惰性肺损伤，目前的治疗仅在 三分之一的案件。 肺损伤后的纤维增生反应是 其特征在于基质纤维蛋白沉积和胶原积聚。 最近的几项体内研究表明，丝氨酸蛋白酶 纤溶酶原激活物抑制剂（派-1）有助于 纤维化反应例如，在博来霉素损伤的小鼠中，派-1升高， 在纤维增生性病变成纤维细胞中调节， 派-1的缺失赋予了对肺损伤诱导的纤维蛋白的保护， 胶原沉积 这些体内数据提供了强有力的证据， 派-1的纤维化作用，然而，参与的调节途径， 成纤维细胞派-1表达尚未阐明。 此外，委员会认为， 派-1的体内作用机制是通过抑制 肺泡纤维蛋白的清除率尚未得到证实。 我们的目标是了解 派-1表达的调控机制及其在肝硬化中的作用 导致肺纤维化的分子事件。 我们最近发现，成纤维细胞上调其表达， 派-1对纤维蛋白D二聚体的反应， 纤维增生性损伤中大量存在的纤维蛋白碎片。 的 本文提出的工作将通过界定机制推动该领域的发展 D二聚体通过其增加成纤维细胞中派-1的表达， 测定肺泡纤维蛋白溶解的体内操作的效果 派-1表达和纤维化过程。 前两 具体目标，我们将确定变化的相对重要性， 派-1转录速率和mRNA半衰期，并确定关键的 基础和D二聚体刺激的派-1中的顺式和反式作用因子 在成纤维细胞中的转录。 在具体目标3中，我们将研究 实验诱导的肺泡纤维蛋白溶解， D二聚体的产生，对肺派-1表达和纤维化的影响 博莱霉素肺损伤的反应。 我们希望， 肺纤维化中的分子事件将导致新的可识别的 治疗方式的目标，旨在减少 肺损伤的纤维增生反应。

Pulmonary fibrosis is a frequent and devastating complication of acute or indolent lung injury for which current therapy is effective in only 1/3 of cases. The fibroproliferative response after lung injury is characterized by matrix fibrin deposition and collagen accumulation. Several recent in vivo studies indicate that the serine protease inhibitor, plasminogen activator inhibitor (PAI-1) contributes to the fibrotic response. For example, in bleomycin-injured mice, PAI-1 is up- regulated in fibroproliferative lesional fibroblasts, and genetic deletion of PAI-1 confers protection from lung injury-induced fibrin and collagen deposition. These in vivo data provide strong evidence of a fibrogenic role for PAI-1, however, the regulatory pathways involved in fibroblast PAI-1 expression have yet to be elucidated. Furthermore, the proposed mechanism of PAI-1's in vivo effect through inhibition of alveolar fibrin clearance remains unproven. Our goal is to understand the mechanism of regulation of PAI-1 expression, and its role in the molecular events that result in pulmonary fibrosis. We have recently shown that fibroblasts up-regulate their expression of PAI-1 in response to fibrin D dimer, a plasmin-generated proteolytic fragment of fibrin that is abundant in fibroproliferative lesions. The work proposed herein will advance the field by defining the mechanism(s) by which D dimer increases PAI-1 expression in fibroblasts, and by determining the effect of in vivo manipulation of alveolar fibrinolysis on PAI-1 expression and on the fibrotic process. In the first two specific aims, we will determine the relative importance of changes in PAI-1 transcription rates and mRNA half-fife, and identify the critical cis and trans acting factors in basal and D dimer-stimulated PAI-1 transcription in fibroblasts. In specific aim 3, we will study effect of experimentally-induced alveolar fibrinolysis, with its attendant generation of D dimer, on lung PAI-1 expression and on the fibrotic response to bleomycin lung injury. We hope the knowledge of the molecular events in pulmonary fibrosis will lead to novel identifiable targets for therapeutic modalities aimed at reducing the fibroproliferative response to lung injury.