Effect of Alcohol on Obesity Related Liver Disease

描述(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。经常饮酒的肥胖个人患脂肪肝(FLD)的风险很高。尽管肥胖和饮酒有共同之处，但不同程度的饮酒对肥胖者FLD的发展和严重程度的影响机制仍然知之甚少。这项建议的目的是阐明不同饮酒量(0-gt；60克/天)影响肥胖者脂肪肝的发生和发展的机制。需要检验的中心假设是：在肥胖者中，饮酒改变了肠道微生物来源的代谢物的循环图谱，这些代谢物激活了循环中的巨噬细胞，导致脂氧合酶(LOX)的系统活性比肥胖患者更高。LOX激活通过促进胰岛素抵抗、氧化应激、炎症和细胞凋亡来加重FLD的严重程度。提出了两个具体目标：(目标1)确定酒精如何通过以下方式增加肥胖者FLD的发展和严重程度：(A)将酒精引起的循环肠道微生物衍生代谢物和二十烷类化合物的变化与导致脂肪肝的途径联系起来，以及肥胖者肠道通透性的变化，(B)在成功完成戒酒计划后，评估酒精诱导的肠道微生物衍生代谢物和二十烷类化合物系统特征变化的可逆性，以及(C)确定特定肠道微生物组衍生代谢产物对体内和体外循环分离巨噬细胞LOX表达的影响以及(目标2)：验证LOX活性与两种互补的脂肪肝小鼠模型FLD表型的相关性，这两种模型将通过胃内给予等热量酒精(Tsukamoto方法)。动物酒精喂养将在NIAAA资助的大学酒精研究中心进行。位于南加州。将采用系统生物学的方法来确定饮酒对全身暴露于肠道微生物衍生代谢物的影响，此类代谢物对循环巨噬细胞LOX表达的影响，二十烷类化合物和肠道微生物衍生代谢物变化对肝脏转录组和组织学的影响，以及停止饮酒者这些变化的可逆性。特定微生物代谢物对LOX活性的影响将通过直接测试它们对从研究对象的循环中分离的巨噬细胞中特定LOX表达的影响来证实。个体LOX的作用将通过使用药理学和遗传学方法来抑制5-LOX和12/15 LOX的活性的功能丧失方法来确定(目标2)。由于他们的专业知识、环境和试剂的可获得性，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全身LOX活性以及这种变化在驱动肝病中的作用的新信息。 公共卫生相关性：这项提案将检验这样一种假设，即酒精消费通过增加肠道细菌来源的循环代谢产物的水平来增加全身脂氧合酶活性，从而促进肥胖者脂肪性肝病的发生。这将通过以下方法进行测试：(1)将酒精诱导的循环代谢物的变化与二十烷基类化合物和通路的激活状态联系起来，以及(2)在两种互补的饮食诱导的肝病小鼠模型中，通过使用药理学和基因敲除方法来确定特定脂肪氧合酶通过抑制它们的作用。当这些研究完成后，将获得关于酒精消费如何改变全身LOX活性以及这种变化在驱动肝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.