Mechanobiology of Lung Fibrosis

描述(申请人提供)：进行性纤维化是间质性肺疾病的标志，如特发性肺纤维化。纤维化使肺实质变硬。这项建议提供的初步数据显示，正常肺实质组织比先前预测的更具顺应性，而纤维化病变的高度局限性僵硬增加比先前所认识的要大得多。生长在像纤维化病变一样坚硬的基质上的成纤维细胞从事快速增殖和丰富的基质合成；与之形成鲜明对比的是，这些行为在与正常肺组织一样顺应的基质上受到很大程度的抑制。基于这些数据，我们提出的中心假设是，肺纤维化中存在的机械环境触发了常驻成纤维细胞的“纤维化形成程序”，促进了疾病的反馈放大。我们提出了四个具体的目标：(1)量化正常肺组织以及正在发展和建立的纤维化病变中实质的硬度；(2)测试基质硬度从正常到纤维化水平的转变是否是肺成纤维细胞增殖和纤维化激活的必要前提；(3)测试细胞骨架动力学和血清反应因子激活在驱动僵硬依赖的成纤维细胞生物学中所起的作用；以及(4)确定在顺应性基质和僵硬基质之间转移时协调成纤维细胞在静止和纤维化状态之间转变的关键转录因子。这些目标将在新的2D和3D模型中实现，这些模型可以清楚地描绘肺基质硬度对肺成纤维细胞关键纤维化行为的影响。在整个实验计划中，我们将检查基质硬度和纤维化中存在的可溶性环境之间的相互作用，因为它影响成纤维细胞生物学。这项研究将对纤维化肺中僵硬依赖的成纤维细胞激活的分子机制产生新的见解，并确定适合于治疗靶点的纤维化形成的关键调节因子。公共卫生相关性：肺纤维化使受影响的组织变得僵硬。这里提出的实验将测试僵硬的病理生理变化是否通过刺激肺成纤维细胞促进纤维化。了解机械因素在成纤维细胞激活中所起的作用可能会导致治疗纤维化的新策略。

DESCRIPTION (provided by applicant): Progressive fibrosis is a hallmark of interstitial lung diseases such as idiopathic pulmonary fibrosis. Fibrosis stiffens the lung parenchyma. Preliminary data provided in this proposal demonstrate that normal lung parenchymal tissue is more compliant than previously predicted, and that highly localized increases in the stiffness of fibrotic lesions are much greater than previously recognized. Fibroblasts grown on substrates as stiff as fibrotic lesions engage in rapid proliferation and abundant matrix synthesis; in marked contrast these behaviors are largely suppressed on substrates as compliant as normal lung tissue. The central hypothesis that we pose based on these data is that the mechanical environment present in lung fibrosis triggers a "fibrogenesis program" in resident fibroblasts that promotes feedback amplification of the disease. We propose four specific aims: (1) quantify the stiffness of the parenchyma in normal lung tissue and developing and established fibrotic lesions; (2) test whether the transition in matrix stiffness from normal to fibrotic levels is a necessary precondition for lung fibroblast proliferation and fibrogenic activation; (3) test the role played by cytoskeletal dynamics and serum response factor activation in driving stiffness-dependent fibroblast biology; and (4) identify key transcription factors coordinating fibroblast transitions between quiescent and fibrogenic states when transferred between compliant and stiff matrices. These aims will be carried out in novel 2D and 3D models that allow clear delineation of the effects of lung matrix stiffness on key fibrogenic behaviors of lung fibroblasts. Throughout the experimental plan we will examine the interplay between matrix stiffness and the soluble environment present in fibrosis as it impacts on fibroblast biology. This research will generate novel insights into the molecular mechanisms of stiffness-dependent fibroblast activation in fibrotic lungs, and identify critical regulators of fibrogenesis suitable for therapeutic targeting. PUBLIC HEALTH RELEVANCE: Lung fibrosis stiffens affected tissue. The experiments proposed here will test whether pathophysiological changes in stiffness promote fibrosis by stimulating lung fibroblasts. Understanding the role mechanical factors play in fibroblast activation could lead to new strategies to treat fibrosis.