Regulation of Collagen Formation in Pulmonary Fibrosis

肌成纤维细胞的激活是间质性肺纤维化的主要特征。这项建议的目的是研究肺肌成纤维细胞表型的调节，重点是这些细胞用来增加基质沉积的信号转导途径。活体肺损伤后，间质壁成纤维细胞表现为肌成纤维细胞表型，α-平滑肌肌动蛋白和α1(I)胶原基因表达增加。我们已经证明，前列腺素E2(PGE2)下调α1(I)胶原、结缔组织生长因子和α-平滑肌肌动蛋白mRNA的稳态水平。PGE2还可激活钙激活的钾通道，使细胞体积减小，并使细胞对死亡受体介导的细胞凋亡敏感。这些结果表明，PGE2抑制肌成纤维细胞表型的表达，具有显著的抗纤维化作用。初步数据表明，用PGE2处理成纤维细胞会导致磷脂酰肌醇3-激酶(PI-3K)减少，这是通过磷酸化蛋白激酶B/Akt的水平来评估的。使用PI-3K和突变Akt结构的抑制剂，我们发现PI-3K系统的活性调节α1(I)胶原mRNA的稳定性。我们假设成纤维细胞的激活和肌成纤维细胞表型的发展涉及PI-3K信号转导通路的活性上调，进而上调α1(I)胶原和α-平滑肌肌动蛋白的mRNA表达。PGE2通过影响PI-3K活性和减少细胞水合作用而下调这些过程。我们计划使用细胞和分子方法在体外和体内验证我们的假设。我们的研究将为肌成纤维细胞的调控提供新的见解，并为肺纤维化的治疗提供新的治疗方案。

The activation of myofibroblast is a central feature of interstitial pulmonary fibrosis. The objective of this proposal is to examine the regulation of the lung myofibroblast phenotype with an emphasis on the signal transduction pathways utilized by these cells to increase matrix deposition. Following lung injury in vivo, fibroblasts in the interstitial wall display a myofibroblast phenotype with increased expression of alpha-smooth muscle actin and alpha1(I) collagen mRNA. We have shown that prostaglandin E2 (PGE2) down-regulated steady state levels for alpha1(I) collagen, connective tissue growth factor and alpha- smooth muscle actin mRNA. PGE2 also stimulated Ca2+ activated K+ channels that decrease cell volume, and sensitized the cells to death receptor mediated apoptosis. These results indicate that PGE2 inhibits expression of the myofibroblast phenotype and has significant anti-fibrogenic properties. Preliminary data indicate that treatment of fibroblasts with PGE2 causes decreases in phosphatidylinositiol 3-kinase (PI-3K) as assessed by levels of phosphorylated protein kinase B/Akt. Employing inhibitors to PI-3K and mutant Akt constructs, we find that the activity of the PI-3K system regulates the stability of the alpha1(I) collagen mRNA. We hypothesize that fibroblast activation and the development of the myofibroblast phenotype involves an up- regulation in the activity of the PI-3K signal transduction pathways which in turn up-regulates alpha1(I) collagen and alpha- smooth muscle actin mRNA expression. PGE2 down-regulates these processes by affecting PI-3K activity and decreasing cell hydration. We plan to use cellular and molecular approaches to test our hypothesis in vitro and in vivo. Our studies will provide new insights into the regulation of the myofibroblast and suggest new therapeutic options for the treatment of pulmonary fibrosis.