MECHANISMS OF PAI1 REGULATION BY LUNG MATRIX MOLECULES

肺纤维化是急性呼吸窘迫综合征的常见和破坏性并发症。 或惰性肺损伤，目前的治疗方法仅对 1/3的病例。肺损伤后的纤维增殖性反应 以基质纤维蛋白沉积和胶原沉积为特征。 最近的几项体内研究表明，丝氨酸蛋白酶 抑制物、纤溶酶原激活物抑制物(PAI-1)参与 纤维化反应。例如，在博莱霉素损伤的小鼠中，PAI-1上调- 在纤维增生性皮损成纤维细胞中的调控，以及基因 PAI-1的缺失对肺损伤诱导的纤维蛋白和 胶原蛋白沉积。这些活体数据提供了强有力的证据表明 然而，PAI-1的致纤维化作用涉及的调节通路 成纤维细胞PAI-1的表达尚不清楚。此外， 纤溶酶原激活物-1‘S抑制纤溶酶原激活剂的体内作用机制 肺泡纤维蛋白清除仍未得到证实。我们的目标是了解 纤溶酶原激活物-1的表达调控机制及其在血管紧张素转换酶中的作用 导致肺纤维化的分子事件。 我们最近发现成纤维细胞上调了它们的蛋白表达 纤溶酶产生的蛋白水解物纤维蛋白D二聚体对PAI-1的影响 纤维增生性病变中丰富的纤维蛋白片段。这个 本文提出的工作将通过定义机制来推进该领域(S) 通过D-二聚体增加成纤维细胞PAI-1的表达，以及通过 活体推拿治疗肺泡纤溶的效果观察 对纤溶酶原激活物-1表达和纤维化过程的影响。在前两个 具体目标，我们将确定变化的相对重要性 PAI-1转录速率和mRNA半衰期，并鉴定关键 基础和D-二聚体刺激的PAI-1顺式和反式作用因子 成纤维细胞中的转录。在具体目标3中，我们将研究效果 实验诱导的肺泡纤溶及其伴随的 D-二聚体的产生对肺组织PAI-1表达和纤维化的影响 对博莱霉素肺损伤的反应。我们希望这方面的知识 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 肺损伤后的纤维增生性反应。

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.