RC#3: Fibroblast Activation and Abnormal Matrix Remodelling

埃默里酒精和肺部生物学中心的成员揭示了乙醇与 滥用和对急性肺损伤的易感性。我们假设乙醇的一种机制是 促进急性肺损伤与激活组织重塑有关，其特点是两者均升高 肺细胞外基质的表达和降解。我们开始在上一次调查中调查这一点 结果表明，长期暴露于乙醇可导致肺组织中乙醇的激活。 基质金属蛋白酶与胶原断裂增加，转化基因表达增加 生长因子-β(TGFp)和参与损伤的基质糖蛋白纤维连接蛋白的表达增加 并进行修复。我们还展示了肺组织重塑激活的证据，在其他情况下是健康的。 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标。因此，我们 现在建议探索乙醇影响成纤维细胞功能的机制，即信号转导 触发的通路，以及细胞外基质作为这些事件的调节器的潜在作用。 有趣的是，我们发现乙醇通过氧化硫醇二硫键对来诱导氧化应激。 激活非神经性烟碱型乙酰胆碱受体(NAChRs)并触发转化生长因子|31/SMAD3信号转导 然后诱导参与基质表达和肌成纤维细胞调控的基因 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。 帮助维持酒精表型，而过氧化物体增殖物激活受体-伽马 (PPARy)下调这些反应。这些新奇的观察结果使我们假设，在肺中 成纤维细胞，乙醇诱导的氧化应激通过nAChRs触发氧化还原信号，导致 TGFp1/Smad3信号转导通路。反过来，TGFp1/SMAD3信号促进成纤维细胞表型和 富含纤维连接蛋白的细胞外基质的产生使肺对纤维增殖易感 在急性肺损伤的背景下。这些事件被PPARy抵消了。这一假设将是 测试的目的是：1)确定负责调节酒精对肺的影响的nAChRs 成纤维细胞。2)研究TGFp1/Smad3信号在乙醇诱导的急性肺易感性中的作用 受伤。3)探讨成纤维细胞来源的富含纤维粘连蛋白的基质促进血管生成的机制。 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，并研究体内对这一途径的操纵如何影响乙醇相关 后果。LAV总结：这个项目将研究长期接触酒精如何激活 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.