Epithelial-Mesenchymal Interactions in Fibrosis Resolution

项目摘要 肺纤维化（PF）仍然是一个主要的和日益增长的医疗负担，治疗选择不令人满意 无法逆转已确立的疾病。我们先前的工作已经确定成纤维细胞中的雅普/TAZ激活是一个重要的因素。 传播PF进展的病理反馈回路的中心特征。在先前的资助周期中， 我们确定多巴胺D1受体（D1 R）激动是选择性抑制肺内雅普/TAZ的策略 成纤维细胞，导致小鼠实验性肺纤维化的加速解决，部分是通过转换 肺成纤维细胞从基质沉积到基质降解状态。此外，我们还证明， 患有PF的个体表现出多巴脱羧酶（DDC）表达的缺陷， L-DOPA转化为生物活性多巴胺。这些研究使我们提出， 肺中的内源性局部多巴胺水平是基质降解和纤维化的重要触发因素 清除是肺成功修复所必需的，但在PF中受损。我们的初步数据显示 博来霉素损伤后幼鼠肺组织中Ddc转录物被短暂抑制， 在纤维化消退期间，而老年小鼠表现出Ddc的持续降低， 纤维化此外，从注射后第21天至第42天，Ddc酶活性或D1 R的小分子抑制作用也被证实。 博来霉素在年轻小鼠中消除肺纤维化的自发消退，证明了其重要作用 多巴胺信号在纤维化消退中的作用。此外，我们发现，多巴胺是检测上清液中的 精确切割的肺切片，在从纤维化肺培养的切片中减少，证实了局部合成 肺内的多巴胺。基于这些发现，我们建议测试中心假设，上皮 多巴胺合成对于纤维化消退和PF肺中正常多巴胺水平的恢复至关重要 组织可以促进胶原蛋白的再吸收和肺的修复。我们将从三个方面来检验这一假设 跨越肺纤维化的非分辨小鼠模型以及小鼠和人的离体模型 肺组织为了确定多巴胺信号传导的功能作用，我们将利用细胞特异性条件反射和细胞特异性条件反射。 遗传模型以及充分表征的小分子抑制剂和多巴胺激动剂， 系统.我们的研究将共同确定控制多巴胺的细胞来源和调节系统 本研究旨在评估正常肺修复过程中的生物利用度，并将描述这种修复系统如何在人类PF中失败。 研究可能揭示促进纤维化消退和肺修复的新治疗方法。

Project Summary Pulmonary fibrosis (PF) remains a major and growing medical burden with unsatisfactory therapeutic options that fail to reverse established disease. Our prior work has identified that YAP/TAZ activation in fibroblasts is a central feature of the pathological feedback loop that propagates progression of PF. In the prior funding cycle, we identified Dopamine D1 receptor (D1R) agonism as a strategy to inactivate YAP/TAZ selectively in lung fibroblasts, leading to accelerated resolution of experimental pulmonary fibrosis in mice in part by switching lung fibroblasts from matrix depositing to matrix degrading state. Moreover, we demonstrated that the lungs of individuals with PF exhibit a deficit in expression of DOPA decarboxylase (DDC), the enzyme that catalyzes conversion of L-DOPA into bioactive dopamine. These studies lead us to propose that restoration of endogenous local dopamine levels in the lung is an essential trigger for the matrix degradation and fibrosis clearance that is essential to successful repair of the lung, but is impaired in PF. Our preliminary data show that Ddc transcripts are transiently depressed in lung tissue of young mice following bleomycin injury and rise during fibrosis resolution, whereas aged mice exhibited sustained reductions in Ddc that parallel persistent fibrosis. Moreover, small molecule inhibition of Ddc enzymatic activity or the D1R from day 21 to 42 post- bleomycin in young mice ablates the spontaneous resolution of lung fibrosis, demonstrating the essential role for dopamine signaling in fibrosis resolution. In addition, we find that dopamine is detectable in supernatants of precision cut lung slices and is diminished in slices cultured from fibrotic lungs, confirming the local synthesis of dopamine within the lung. Based on these findings, we propose to test the central hypothesis that epithelial dopamine synthesis is essential to fibrosis resolution and that restoration of normal dopamine levels in PF lung tissue can promote collagen resorption and repair of the lung. We will test this hypothesis in three aims spanning non-resolving mouse models of pulmonary fibrosis as well as ex vivo models of mouse and human lung tissues. To define the functional roles of dopamine signaling we will leverage both cell-specific conditional genetic models as well as well-characterized small molecule inhibitors and dopamine agonists in these systems. Together our studies will define the cellular sources and regulatory systems that control dopamine bioavailability during normal lung repair, and will delineate how this repair system fails in human PF. These studies may reveal new therapeutic approaches to promote fibrosis resolution and lung repair.