Matrix Regulation of Pulmonary Fibrosis

描述(由申请人提供)：控制严重和进行性肺纤维化的机制仍然知之甚少。本项目侧重于阐明细胞外基质在非感染性肺损伤背景下调节肺部炎症和纤维化中的作用。在这一资助期间，我们实验室的工作重点是细胞外糖胺聚糖透明质酸(HA)在调节肺部炎症和纤维化中的作用。我们已经确定了HA的不同功能，这取决于它表达的细胞环境和它被呈现给相互作用的细胞的形式。我们发现，表达在肺上皮细胞表面的HA对非感染性损伤具有保护作用。相反，当肌肉成纤维细胞在α-平滑肌肌动蛋白启动子(ASMA-HAS2)的控制下过度表达透明质酸合成酶2(HAS2)时，结果是损伤后严重的进行性纤维破坏性肺疾病，导致显著死亡。我们已经做了令人兴奋的观察，从ASMA-HAS2小鼠分离的成纤维细胞具有侵袭性表型。我们还产生了第一个间质靶向的HAS2表达缺失，并发现成纤维细胞的纤维化和基质侵袭都是钝化的。基于这些数据，我们提出了一个假设，即严重的进行性肺纤维化需要发展成依赖于HAS2的侵袭性成纤维细胞表型。我们将在以下特定目标中验证这一假说：1.确定HAS2在调节进行性肺纤维化和侵袭性成纤维细胞表型发展中的作用。2.探讨HAS2在转化生长因子-β转基因小鼠肺纤维化形成中的作用。3.通过对肺泡上皮、间皮细胞和肺成纤维细胞的谱系标记，确定侵袭性成纤维细胞表型的来源。4.鉴定重度肺纤维化基质侵袭性成纤维细胞的基因组特征，阐明调控侵袭性的信号通路。

DESCRIPTION (provided by applicant): The mechanisms that control severe and progressive pulmonary fibrosis remain poorly understood. This program has focused on elucidating the roles of the extracellular matrix in regulating lung inflammation and fibrosis in the context of non-infectious lung injury. Work from our laboratory during this period of funding has focused on the role of the extracellular glycosaminoglycan hyaluronan (HA) in regulating lung inflammation and fibrosis. We have identified distinct functions for HA depending on both the cellular context of its expression and the form in which it is presented to interacting cells. We have discovered that HA expressed on the cell surface of lung epithelial cells serves a protective function against non-infectious insults. In contrast, when myofibroblasts are directed to over-express hyaluronan synthase 2 (has2) under control of the alpha-smooth muscle actin promoter (ASMA-HAS2), the result is a severe and progressive fibrodestructive lung disease after injury that causes significant mortality. We have made the exciting observation that fibroblasts isolated from ASMA-HAS2 mice have an invasive phenotype. We have also generated the first mesenchymal-targeted deletion of has2 expression and found that both fibrosis and matrix invasion of fibroblasts is blunted. Based on these data we have generated the hypothesis that severe and progressive lung fibrosis requires the development of an invasive fibroblast phenotype dependent upon has2. We will test this hypothesis in the following Specific Aims: 1. Determine the roles of has2 in regulating progressive lung fibrosis and the development of an invasive fibroblast phenotype. 2. Determine the role of has2 in regulating the development of pulmonary fibrosis in TGF-¿ transgenic mice. 3. Determine the source of the invasive fibroblast phenotype using lineage labeling of alveolar epithelium, mesothelium and resident lung fibroblasts. 4. Identify genomic signatures of matrix-invading fibroblasts from severe pulmonary fibrosis and elucidate the signaling pathways that regulate invasion.