RC#3: Fibroblast Activation and Abnormal Matrix Remodelling

埃默里酒精和肺生物学中心的成员揭示了乙醇和肺之间的强烈联系。 滥用和易患急性肺损伤。我们假设乙醇的一种机制 促进急性肺损伤与组织重塑的激活有关，其特征在于两者的增加 肺细胞外基质的表达和降解。我们开始调查这一点， 研究表明，啮齿动物长期暴露于乙醇会导致肺部激活 基质金属蛋白酶和胶原断裂增加，转化蛋白表达增加， 生长因子-β 1（TGF β）和纤连蛋白（一种与损伤有关的基质糖蛋白）表达增加 和修复。我们还发现，在其他“健康”的人中， 酗酒者更重要的是，这些研究揭示了肺成纤维细胞是乙醇的靶点。因此我们 现在建议探索乙醇影响成纤维细胞功能的机制， 触发的途径，以及细胞外基质作为这些事件的调节剂的潜在作用。 有趣的是，我们发现乙醇诱导的氧化应激通过氧化硫醇二硫键对， 激活非神经元烟碱乙酰胆碱受体（nAChR）并触发TGF| 31/Smad 3信号通路 随后诱导参与控制基质表达和肌成纤维细胞的基因， 转分化我们还发现，这一途径导致富含纤维连接蛋白的基质沉积 这有助于维持“酒精表型”，而过氧化物酶体增殖物激活受体-γ （PPARy）下调这些反应。这些新的观察结果使我们假设，在肺中， 乙醇诱导的氧化应激通过nAChR触发氧化还原信号传导， TGF β 1/Smad 3信号转导。反过来，TGF β 1/Smad 3信号促进成纤维细胞表型的改变， 产生富含纤连蛋白的细胞外基质，使肺易于纤维增生 在急性肺损伤的情况下。这些事件被PPARy抵消。这一假设将是 测试的目的是：1）确定负责介导肺中乙醇作用的nAChR 成纤维细胞2)研究TGF β 1/Smad 3信号在乙醇诱导的急性肺损伤易感性中的作用 损伤3)探索成纤维细胞来源的富含纤维连接蛋白的基质促进细胞凋亡的机制。 乙醇诱导的效应。4)确定PPARy在下调乙醇诱导的成纤维细胞中的作用 激活和基质表达，并检查如何操纵这一途径在体内影响乙醇相关的 后果本项目将研究长期暴露于酒精如何激活 肺成纤维细胞和促进急性肺损伤。

Members of the Emory Alcohol and Lung Biology Center unveiled a strong association between ethanol abuse and susceptibility to acute lung injury. We hypothesized that one mechanism by which ethanol promotes acute lung injury relates to the activation of tissue remodeling characterized by both increased expression and degradation of lung extracellular matrices. We set out to investigate this during the prior funding period and showed that chronic exposure to ethanol in rodents leads to the activation in lung of matrix metalloproteinases and increased collagen fragmentation, increased expression of Transforming Growth Factor-pi (TGFp), and increased expression of fibronectin, a matrix glycoprotein implicated in injury and repair. We also showed evidence of activation of lung tissue remodeling in otherwise 'healthy' alcoholics. More importantly, these studies unveiled the lung fibroblast as a target for ethanol. Thus, we now propose to explore the mechanisms by which ethanol affects fibroblast functions, the signaling pathways triggered, and the potential role of extracellular matrices as modulators of these events. Interestingly, we found that ethanol-induced oxidative stress via oxidation of thiol disulfide couples activates non-neuronal nicotinic acetylcholine receptors (nAChRs) and triggers TGF|31/Smad3 signaling followed by the induction of genes involved in control of matrix expression and myofibroblast transdifferentiation. We also found that this pathway results in the deposition of fibronectin-rich matrices that help sustain the 'alcoholic phenotype', whereas peroxisome proliferator activated receptors-gamma (PPARy) downregulate these responses. These novel observations led us to postulate that in lung fibroblasts, ethanol-induced oxidative stress triggers redox signaling via nAChRs that leads to TGFp1/Smad3 signaling. In turn, TGFp1/Smad3 signaling promotes alterations in fibroblast phenotype and the production of fibronectin-rich extracellular matrices that render the lung susceptible to fibroproliferation in the setting of acute lung injury. These events are counterbalanced by PPARy. This hypothesis will be tested in aims designed to: 1) Identify the nAChRs responsible for mediating the effects of ethanol in lung fibroblasts. 2) Examine the role of TGFp1/Smad3 signaling in ethanol-induced susceptibility to acute lung injury. 3) Explore the mechanisms by which fibroblast-derived fibronectin-rich matrices contribute to the ethanol-induced effects. 4) Determine the role of PPARy in downregulating ethanol-induced fibroblast activation and matrix expression, and examine how manipulation of this pathway in vivo affects ethanolrelated consequences. Lav summary: This project will examine how chronic exposure to alcohol activates lung fibroblasts and promotes acute lung injury.