Regulation of the innate immune response in alcoholic liver disease by autophagy

描述(申请人提供)：酒精性肝病(ALD)是美国最常见的肝病之一，也是慢性肝功能衰竭和死亡的主要原因。ALD的肝损伤机制尚不清楚，因此目前还没有针对这种疾病的有效治疗方法。ALD发展的关键是过度活跃的肝脏天然免疫反应。激活的常驻Kupffer细胞和招募的巨噬细胞产生导致脂肪变性、肝细胞损伤和纤维化的可溶性因子。最近的发现表明，酒精促进促炎的M1而不是抗炎的M2巨噬细胞极化。我们先前的研究已经确定了自噬的溶酶体降解途径在调节细胞信号通路和介导M1和M2巨噬细胞极化的脂代谢中的新功能。这项建议的目的是描述自噬调节巨噬细胞极化的机制，以及由于ALD过度活跃的促炎反应而导致的肝损伤。初步研究结果表明，脂肪变性和酒精抑制巨噬细胞自噬，而乙醇和受损的自噬共同作用于阻断M2巨噬细胞极化。此外，我们还产生了巨噬细胞特异性的自噬敲除，并表明它们对内毒素或乙醇引起的促炎反应和肝损伤的发展具有敏感度。基于这些和其他初步研究，我们的中心假设是酒精损害巨噬细胞的自噬，促进促炎巨噬细胞的极化和激活，导致过度活跃的先天免疫反应和ALD。我们将在三个特定目标的研究中检验这一假设，这些研究将描绘酒精减少巨噬细胞自噬的机制，以及这种影响如何改变巨噬细胞极化和肝脏对酒精的先天免疫反应的产生。首先，我们将验证酒精通过抑制AMP激活的蛋白激酶信号而降低巨噬细胞自噬功能的假设。其次，我们将检验酒精诱导的自噬缺陷通过对内质网应激和线粒体�氧化的影响促进M1并抑制M2巨噬细胞极化的假设。第三，我们将检验这一假设，即体内巨噬细胞自噬减少通过导致不受抑制的促炎免疫反应来促进ALD的发展。这些研究的目的是描绘新的范例，通过自噬的溶酶体途径调节肝脏对酒精的促炎性先天免疫反应。这些研究的最终目的是为了更好地了解酒精引起肝损伤的基本细胞机制，以便设计新的策略来预防和治疗人类酒精性肝病。

DESCRIPTION (provided by applicant): Alcoholic liver disease (ALD) is one of the most common liver diseases in the United States and a major cause of chronic liver failure and mortality. The mechanisms of liver injury in ALD remain unclear and as a result there is no proven therapy for this disease. Critical to the development of ALD is an overactive hepatic innate immune response. Activated resident Kupffer cells and recruited macrophages generate soluble factors that lead to steatosis, hepatocellular injury and fibrosis. Recent findings indicat that alcohol promotes proinflammatory M1 rather than anti-inflammatory M2 macrophage polarization. Our prior investigations have identified novel functions for the lysosomal, degradative pathway of autophagy in the regulation of cellular signaling pathways and lipid metabolism that mediate M1 and M2 macrophage polarization. The objective of this proposal is to delineate mechanisms by which autophagy regulates macrophage polarization and the hepatic injury that occurs as the result of the overactive proinflammatory response in ALD. Preliminary findings demonstrate that steatosis and alcohol inhibit macrophage autophagy, and that ethanol and impaired autophagy act in concert to block M2 macrophage polarization. In addition, we have generated macrophage- specific mouse knockouts of autophagy and shown that they are sensitized to the development of a proinflammatory response and liver injury from lipopolysaccharide or ethanol. Based on these and other preliminary studies, our central hypothesis is that alcohol impairs macrophage autophagy which promotes proinflammatory macrophage polarization and activation leading to an overactive innate immune response and ALD. We will test this hypothesis in studies contained in three Specific Aims that will delineate the mechanism by which macrophage autophagy is decreased by alcohol, and how this effect alters macrophage polarization and the generation of a hepatic innate immune response to alcohol. First, we will test the hypothesis that alcohol decreases autophagic function in macrophages by inhibiting AMP-activated protein kinase signaling. Second, we will test the hypothesis that an alcohol-induced defect in autophagy promotes M1 and inhibits M2 macrophage polarization through effects on ER stress and mitochondrial �-oxidation. Third, we will test the hypothesis that decreased autophagy in macrophages in vivo promotes ALD development by leading to an unrestrained proinflammatory immune response. The objective of these studies is to delineate novel paradigms by which the lysosomal pathway of autophagy regulates the hepatic proinflammatory innate immune response to alcohol. The ultimate goal of these investigations is to better understand the basic cellular mechanisms underlying the development of liver injury from alcohol in order to design new strategies to prevent and treat human ALD.