Mitochondrial depolarization, mitophagy, and mitochondrial DAMPs in ALD

酒精性肝病(ALD)占因肝硬变死亡的约50%，占所有与肝脏相关的死亡的约30% 美国的死亡人数。乙醇如何损害肝脏仍然知之甚少，也缺乏治疗方法或 未经证实。我们的目标是了解ALD的发病机制。我们观察到广泛的、可逆的肝脏 线粒体去极化(MtDepo)、线粒体负荷增加和血清线粒体DNA升高 (线粒体DNA)在乙醇处理后的小鼠。我们建议检验乙醇新陈代谢的新假说 诱导mtDepo，进而刺激有丝分裂。显著增加的丝裂原细胞负担 使溶酶体处理自噬小体的能力不堪重负，尤其在处理 去极化的线粒体进入有丝噬菌体，然后进入溶酶体，在 慢性酒精暴露，导致受损线粒体、线粒体胞外释放 和/或含有线粒体损伤相关分子模式的自溶酶体(MtDAMP) 导致促纤维化炎症反应和肝脏损伤的分子。在具体目标1中使用 活体多光子显微镜，我们将探索mtDepo是否发生在慢性乙醇后的活小鼠中，并 在一种独特的导致肝纤维化的酒精/胆固醇模型中，我们 发展起来的。我们将确定mtDepo与肝损伤、炎症和纤维化的关系。我们还将 探讨乙醇脱氢酶和细胞色素P450_2E_1缺乏对乙醛形成的抑制作用， ALDA-1和FK506(去极化阻滞剂)加速乳酸氧化降低线粒体深度和肝脏 慢性酒精后的损伤/炎症/纤维化。在目标2中，我们将确定mtDepo与 有丝分裂。结合活体和电子技术使用遗传和药物干预 显微镜和分子指示剂的分析，我们将阐明乙醇是否诱导 MtDepo引发有丝分裂，或者如果有丝分裂导致mtDepo。我们将确定是否有丝分裂/有丝分裂小体 慢性、慢性加胆固醇和慢性加酗酒使加工变钝，并进一步探索 抑制自噬过程会加剧慢性酒精中毒后的肝脏损伤/炎症/纤维化。在AIM 3，我们将表征mtDepo和受损的有丝分裂吞噬/加工如何促进mtDAMP的释放 在乙醇之后。我们将表征急性乙醇和慢性、慢性后mtDAMPs在血清中的释放。 加胆固醇和慢性加酗酒确定mtDAMP释放与肝脏的关系 损伤/炎症/纤维化。我们还将确定mtDepo的上调和下调、有丝分裂和 线粒体的处理改变了乙醇后线粒体DAMP的释放。这项研究将阐明一种新的联系 与酒精代谢相关的早期线粒体改变与肝脏后期发育之间的关系 损伤/炎症/纤维化，从而填补了理解ALD发病机制的关键空白。这项研究应该 同时确定ALD的新治疗靶点和用于监测ALD严重程度/进展的新生物标记物。

Alcoholic liver disease (ALD) accounts for ~50% of deaths due to cirrhosis and ~30% of all liver-related deaths in the US. How ethanol damages the liver remains poorly understood, and therapies are lacking or unproven. Our goal is to understand the pathogenesis of ALD. We observed widespread, reversible hepatic mitochondrial depolarization (mtDepo), increased mitophagic burden and elevated serum mitochondrial DNA (mtDNA) in mice after ethanol treatment. We propose to test the novel hypothesis that ethanol metabolism induces mtDepo, which in turn stimulates mitophagy. Markedly increased mitophagic burden overwhelms the capacity of lysosomes to process autophagosomes, particularly when processing of depolarized mitochondria into mitophagosomes and then into lysosomes is compromised after chronic ethanol exposure, leading to extracellular release of damaged mitochondria, mitophagosomes and/or autolysosomes containing mitochondrial damage-associated molecular pattern (mtDAMP) molecules to cause a profibrotic inflammatory response and liver injury. In Specific Aim 1 using intravital multiphoton microscopy, we will explore if mtDepo occurs in living mice after chronic ethanol and is exacerbated by superimposed binge drinking and in an unique fibrosis-inducing ethanol/cholesterol model we developed. We will determine the relation of mtDepo to hepatic injury, inflammation and fibrosis. We will also explore if inhibition of acetaldehyde (AcAld) formation by alcohol dehydrogenase and CYP2E1 deficiency, accelerated AcAld oxidation by Alda-1, and FK506 (blocker of depolarization) decrease mtDepo and liver injury/inflammation/fibrosis after chronic ethanol. In Aim 2, we will determine the relation of mtDepo to mitophagy. Using genetic and pharmacological interventions in combination with intravital and electron microscopy and analyses of molecular indicators of mitophagic flux, we will elucidate if ethanol-induced mtDepo initiates mitophagy or if mitophagy causes mtDepo. We will determine if mitophagy/mitophagosome processing is blunted by chronic, chronic plus cholesterol and chronic plus binge ethanol and further explore if inhibition of autophagic processing exacerbates liver injury/inflammation/fibrosis after chronic ethanol. In Aim 3, we will characterize how mtDepo and compromised mitophagy/processing contribute to mtDAMP release after ethanol. We will characterize release into serum of mtDAMPs after acute ethanol and chronic, chronic plus cholesterol and chronic plus binge ethanol to determine the relationship of mtDAMP release to liver injury/inflammation/fibrosis. We will also determine how up and down-modulation of mtDepo, mitophagy and processing of mitophagosomes alters mtDAMP release after ethanol. This study will elucidate a novel link between early mitochondrial changes associated with ethanol metabolism and the later development of liver injury/inflammation/fibrosis and thus fill a critical gap in understanding ALD pathogenesis. This study should also identify new therapeutic targets of ALD and novel biomarkers for monitoring ALD severity/progression.