Effect of Alcohol on Obesity Related Liver Disease

描述（由申请人提供）：肥胖和酒精相关疾病是两个非常普遍和重要的公共卫生问题。经常饮酒的肥胖者患脂肪肝（FLD）的风险很高。尽管肥胖和饮酒具有共性；不同酒精摄入量对肥胖个体FLD发展和严重程度的影响机制尚不清楚。本研究的目的是阐明不同饮酒量（0- 60克/天）影响肥胖受试者脂肪肝疾病发生和进展的机制。要验证的中心假设是：在肥胖受试者中，饮酒改变了肠道微生物来源的代谢物的循环特征，这些代谢物激活了循环巨噬细胞，导致脂氧合酶（LOX）的全身活性增加，超过肥胖单独出现的情况。LOX激活通过促进胰岛素抵抗、氧化应激、炎症和细胞凋亡来驱动FLD的严重程度。提出了两个具体目标：（目标1）通过(a)将酒精诱导的循环肠道微生物衍生代谢物和类二十烷类物质的变化与驱动脂肪肝疾病的途径以及肥胖受试者肠道通透性的变化联系起来，(b)评估酒精诱导的肠道微生物衍生代谢物和类二十烷类物质的系统性变化在成功完成戒酒计划后的可复性，确定酒精如何增加肥胖受试者FLD的发展和严重程度。(c)确定特定肠道微生物衍生代谢物对循环分离的巨噬细胞体内和体外LOX表达的影响（目的2）：在两种互补的脂肪性肝病小鼠模型中验证LOX活性与FLD表型的相关性，这些模型将通过胃内途径给予等热量酒精喂养（Tsukamoto方法）。动物酒精喂养将在niaaa资助的南加州大学酒精研究中心进行。将采用系统生物学方法来定义饮酒对全身暴露于肠道微生物衍生代谢物的影响，这些代谢物对循环巨噬细胞中LOX表达的影响，改变的类二十烷和肠道微生物衍生代谢物对肝脏转录组和组织学的影响，以及停止饮酒的人这些变化的可逆性。特异性微生物代谢物对LOX活性的影响将通过直接测试其对研究对象循环中分离的巨噬细胞特异性LOX表达的影响来证实。单个LOX的作用将通过使用药理学和遗传学方法来降低5-LOX和12/15 LOX的活性来确定（目的2）。由于他们的专业知识、环境和获得试剂的途径，研究人员非常适合进行拟议的研究。当这些研究完成后，将获得关于酒精摄入如何改变系统性LOX活性以及这种变化在驱动肝脏疾病中的作用的新信息。

DESCRIPTION (provided by applicant): Obesity- and alcohol-related diseases are two highly prevalent and important public health problems. Obese individuals who consume alcohol regularly are at high risk of developing fatty liver disease (FLD). Despite the commonality of obesity and alcohol consumption; the mechanisms by which varying amounts of alcohol consumption affect the development and severity of FLD in obese individuals remain poorly understood. The objective of this proposal is to elucidate the mechanisms by which varying amounts (0->60 gm/day) of alcohol consumption affect the development and progression of fatty liver disease in obese subjects. The central hypothesis to be tested is: In obese subjects, alcohol consumption alters the circulating profile of metabolites of intestinal microbial origin which activate circulating macrophages resulting in increased systemic activity of lipoxygenases (LOX) over and above that seen in obesity alone. LOX activation drives the severity of FLD by promoting insulin resistance, oxidative stress, inflammation and apoptosis. Two specific aims are proposed: (Aim 1) Define how alcohol increases the development and severity of FLD in obese subjects by (a) relating alcohol-induced changes in circulating gut microbiome-derived metabolites and eicosanoids to pathways driving fatty liver disease, and changes in intestinal permeability in obese subjects, (b) evaluation of the reversibility of alcohol-induced changes in the systemic profile of gut microbiome-derived metabolites and eicosanoids after successful completion of an alcohol cessation program, and (c) determining the effects of specific intestinal microbiome derived metabolites on LOX expression in vivo and in vitro in macrophages isolated from circulation and (Aim 2): To validate the relevance of LOX activity on the phenotype of FLD in two complementary mouse models of fatty liver disease that will be given isocaloric alcohol feeding via an intragastric route (Tsukamoto method). The animal alcohol feeding will be performed at the NIAAA-funded alcohol research center at the Univ. of Southern California. A systems biology approach will be taken to define the effects of alcohol consumption on systemic exposure to gut microbiome-derived metabolites, impact of such metabolites on LOX expression in circulating macrophages, impact of altered eicosanoid and intestinal microbiome-derived metabolite profile on the hepatic transcriptome and histology and the reversibility of these changes in those who cease to consume alcohol. The effects of specific microbial metabolites on LOX activity will be corroborated by directly testing their effects on specific LOX expression in macrophages isolated from circulation of the study subjects. The role of individual LOX will be determined by a loss of function approach using both pharmacologic and genetic methods to knock down the activity of 5-LOX and 12/15 LOX (aim 2). The investigators are uniquely suited to perform the proposed studies because of their expertise, environment and access to reagents. When these studies are completed, novel information on how alcohol intake modifies systemic LOX activity and the role of such changes in driving liver disease will be obtained. PUBLIC HEALTH RELEVANCE: This proposal will test the hypothesis that alcohol consumption enhances the development of fatty liver disease in obese individuals by increasing systemic lipoxygenase activity by increased levels of circulating metabolites of intestinal bacterial origin that activate macrophages to express lipoxygenases. This will be tested by: (1) linking alcohol-induced changes in circulating metabolome to eicosanoids and to the activation status of pathways, and (2) defining the role of specific lipoxygenases by their suppression using pharmacologic and genetic knockdown methods in two complementary diet-induced mouse models of liver disease. When these studies are completed, novel information on how alcohol consumption modifies systemic LOX activity and the role of such changes in driving liver disease will be obtained.