Microbiome and intestinal innate immune response in alcoholic liver disease

描述（由申请人提供）：酒精相关的健康问题是工业化国家的主要医疗负担。酒精性肝病以脂肪变性为特征，可发展为酒精性肝炎、纤维化或肝硬化。酒精性肝病患者表现为肠道细菌过度生长和生态失调。它们还表明肠道通透性增加，疾病严重程度与全身细菌产物水平相关。尽管实验性酒精性肝病依赖于肠道衍生的细菌产物，但尚不清楚酒精如何破坏粘膜屏障并介导肠道微生物群的变化。我们实验室的结果表明，肠道微生物组的定性和定量变化是通过抑制粘膜先天免疫系统，特别是抑菌分子如再生胰岛衍生的3- γ (Reg3g)而促进的。抗菌分子表达的减少开辟了一个空间生态位，使某些具有致病活性的细菌菌株能够生长，从而增强细菌易位。本应用的重点是进一步表征酒精、肠道先天免疫系统和肠道菌群变化之间的关系。我们的实验方法是使用灌胃酒精喂养的小鼠模型来研究抗菌蛋白对与肝脏疾病相关的肠道生态失调和细菌过度生长的贡献（目的1）。然后，我们将评估微生物组变化的后果及其对细菌易位的贡献。重点将放在嗜粘阿克曼氏菌上，这种细菌是在酒精喂养后诱导的。我们将测试嗜黏液Akkermansia muciniphila通过降解肠道黏液层促进细菌易位的新概念（Aim 2）。然后，我们将通过使用益生元改变肠内营养的可用性来控制酒精诱导的生态失调。系统生物学方法与新的和强大的焦磷酸测序方法将用于监测宿主转录组和肠道微生物组的变化，在给予益生元后（目标3）。我们相信这些研究将为酒精介导的肠道先天免疫系统的变化提供重要的见解，这些变化导致肠道微生物群和细菌易位的变化。最终，这种方法可能会为酒精性肝病患者带来新的治疗靶点。

DESCRIPTION (provided by applicant): Alcohol associated health problems are a major medical burden in industrialized countries. Alcoholic liver disease is characterized by steatosis and may progress to alcoholic hepatitis, fibrosis, or cirrhosis. Patients with alcoholic liver disease show intestinal bacterial overgrowth and dysbiosis. They also demonstrate increased intestinal permeability, and disease severity correlates with systemic levels of bacterial products. Although experimental alcoholic liver disease is dependent on gut derived bacterial products, yet it is unknown how alcohol disrupts the mucosal barrier and mediates changes in the enteric microbiome. Results from our laboratory suggest that qualitative and quantitative changes in the intestinal microbiome are facilitated by suppression of the mucosal innate immune system and in particular of antimicrobial molecules such as regenerating-islet derived 3-gamma (Reg3g). Reduced expression of antimicrobial molecules opens up a spatial niche that enables the growth of certain bacterial strains with pathogenic activity enhancing bacterial translocation. The focus of this application is to further characterize the relationship between alcohol, the intestinal innate immune system and changes in the intestinal microflora. Our experimental approach is to use a mouse model of intragastric alcohol feeding to investigate the contribution of antimicrobial proteins to intestinal dysbiosis and bacterial overgrowth associated with liver disease (Aim 1). We will then assess the consequences of microbiome changes and their contribution to bacterial translocation. The focus will be on the bacterial species Akkermansia muciniphila that is induced following alcohol feeding. We will test the new concept that Akkermansia muciniphila facilitates bacterial translocation by degrading the intestinal mucus layer (Aim 2). We will then manipulate alcohol-induced dysbiosis by altering enteral nutrient availability using prebiotics. A system biology approach with new and powerful methods for pyrosequencing will be used for monitoring changes in the host transcriptome and the enteric microbiome, following administration of prebiotics (Aim 3). We believe these studies will provide important insights into alcohol-mediated changes of the intestinal innate immune system that result in changes in the intestinal microbiome and bacterial translocation. Eventually this approach might lead to new therapeutic targets for patients with alcoholic liver disease. PUBLIC HEALTH RELEVANCE: Alcoholic liver disease affects several million people in the United States, and alcohol abuse is the most important cause of liver cirrhosis in industrialized countries. Gut-derived bacterial products are necessary for progression of alcoholic liver disease, but the exact mechanisms of intestinal bacterial overgrowth and translocation are poorly understood. Understanding the mechanisms by which alcohol results in intestinal bacterial overgrowth and promotes bacterial translocation by increasing intestinal permeability would greatly enhance our ability to design preventive and therapeutic interventions for patients with chronic alcohol abuse.