Role of fibrotic extracellular matrix in generating the IPF Fibroblast

描述（由申请人提供）：特发性肺纤维化（IPF）是一种致死性纤维化肺疾病，每年导致4万美国人死亡，全球超过100万人死亡。在IPF中，肺泡间充质细胞群的持续扩张和改变导致病变肌成纤维细胞的产生，介导气体交换表面的进行性瘢痕形成，导致窒息死亡。来源于IPF患者肺部的成纤维细胞具有与正常细胞区分的表型特征。IPF成纤维细胞改变整合素表达，具有高增殖性，产生更多的胶原蛋白，表达更多的平滑肌肌动蛋白（MA），并在模式生物中形成纤维化病变。我们最近发表了病理性肺间充质祖细胞（MPCs）是IPF成纤维细胞的起源细胞；IPF细胞外基质（ECM）重编程成纤维细胞基因表达，建立一个正反馈回路，翻译激活ECM基因及其同源细胞表面受体。在这个项目中，我们总结了我们的范式转换数据。首先，我们发现IPF肺MPCs -而不是控制肺MPCs -产生具有IPF成纤维细胞体外和体内特征的后代。接下来，我们表明，当原代肺成纤维细胞（IPF或对照）与去细胞化的肺ECM （IPF或对照）相互作用时：i) ECM来源主要决定基因表达；ii) IPF肺ECM通过翻译激活ECM基因及其同源整合素受体编码基因；iii) IPF肺ECM，而不是控制ECM，降低成纤维细胞miR29的表达，miR29是ECM和增殖基因的有效负调节因子，创造了一个积极的反馈循环，为无情的疾病进展提供了分子机制。基于此，我们假设去细胞化的IPF肺ECM将引导人肺MPC向IPF表型分化；并通过对miR29表达的表观遗传调控来稳定该表型，从而创建一个正反馈回路，驱动控制IPF成纤维细胞标志的基因。我们提出了两个具体的目标来阐明分子机制。特异性目标1:IPF成纤维细胞的起源-表征MPCs在IPF肺ECM中获得IPF表型特征的机制。特异性目标2：疾病进展-剖析IPF ECM驱动的正反馈回路的分子和细胞机制，该回路增加整合素和ECM基因表达并抑制其负调节因子miR29。如果我们实现了我们的目标，我们的工作将揭示控制IPF成纤维细胞及其病理ECM的发生，维持和繁殖的机制。这些信息是开发针对驱动IPF的ECM -间充质细胞相互作用的治疗方法的基础。

DESCRIPTION (provided by applicant): Idiopathic Pulmonary Fibrosis (IPF) is a lethal fibrotic lung disorder that kills 40,000 Americans each year and over 1 million persons worldwide. In IPF, relentless expansion and alteration of the alveolar mesenchymal cell population leads to production of diseased myofibroblasts that mediate progressive scarring of the gas exchange surface resulting in death by asphyxiation. Fibroblasts derived from the lungs of IPF patients have phenotypic hallmarks that distinguish them from their normal counterparts. IPF fibroblasts have altered integrin expression, are hyperproliferative, produce increased amounts of collagen, express increased amounts of �mooth muscle actin (�MA) and form fibrotic lesions in model organisms. We recently published that pathological lung mesenchymal progenitor cells (MPCs) are a cell-of-origin for the IPF fibroblast; and that IPF extracellular matrix (ECM) reprograms fibroblast gene expression to establish a positive feedback loop that translationally activates ECM genes and their cognate cell surface receptors. In this project we summarize our paradigm-shifting data. First, we show that IPF lungs MPCs - but not control lung MPCs - generate progeny with the in vitro and in vivo hallmarks of IPF fibroblasts. Next, we show that when primary lung fibroblasts (IPF or control) interact with decellularized lung ECM (IPF or control): i) the ECM source predominantly dictates gene expression; ii) IPF lung ECM translationally activates ECM genes and genes encoding their cognate integrin receptors; and iii) IPF lung ECM, but not control ECM, decreases fibroblast expression of miR29 - a potent negative regulator of ECM and proliferation genes - creating a positive feedback loop that provides a molecular mechanism for relentless disease progression. Based on this, we hypothesize that decellularized IPF lung ECM will direct human lung MPC differentiation towards the IPF phenotype; and stabilize that phenotype by epigenetic regulation of miR29 expression to create a positive feedback loop driving genes governing IPF fibroblast hallmarks. We propose 2 specific aims to elucidate the molecular mechanisms. Specific Aim 1: Genesis of the IPF fibroblast - Characterize the mechanisms by which MPCs acquire IPF phenotypic hallmarks on IPF lung ECM. Specific Aim 2: Disease Progression - Dissect the molecular and cellular mechanisms of the IPF ECM-driven positive feedback loop that increases integrin and ECM gene expression and suppresses their negative regulator, miR29. If we achieve our aims, our work will unveil mechanisms governing the genesis, maintenance and propagation of the IPF fibroblast and its pathological ECM. This information is foundational for developing therapies that target those ECM - mesenchymal cell interactions that drive IPF.