Bile Acids and Gut Microbiome in the Pathogenesis of Inflammation in Cirrhosis

描述（由申请人提供）： 酒精性肝病和肝硬化是美国以及VA卫生系统发病率和死亡率的主要原因之一。然而，尽管有几个预防和治疗酒精滥用的计划，仍有相当一部分受影响的退伍军人继续饮酒，即使是在肝硬化的情况下。这可能导致大量的负担，这些负担源于未经检查的炎性环境和内毒素血症，这些内毒素血症是由于细菌移位引起的，从而加速感染、多器官衰竭和死亡。这些患者是禁欲药物治疗的不良候选人，通常不依从，并且由于他们持续饮酒而不能提供肝移植。因此，预防这种未经检查的炎症和细菌易位至关重要;然而，这些背后的确切机制尚不清楚，这是我们知识中的一个主要空白。胆汁酸（BA）和肠道微生物群是肠道环境的关键组成部分，它们的相互作用影响细菌移位和炎症。我们的小组已经专注于使用非培养物依赖性分析来描绘微生物群与炎症的作用及其由BA（特别是膜不稳定的继发性BA）在肝硬化中的调节。我们还发现，积极饮用抗凝血剂具有粪便继发性BA和肠道炎性细胞因子表达的高度显着增加，这可能介导这些患者的肠道损伤并增强炎症。因此，在肠道微生物群改变或生态失调的背景下，与戒酒的酒精性酒精性肝病和非酒精性肝病的酒精性肝病相比，在主动饮用酒精性肝病的情况下，研究继发性BA在肠道和全身性炎症发病机制中的作用对于阐明肠道环境在肝病进展中的作用至关重要。我们的中心假设：肝硬化患者，特别是持续饮酒的酒精性肝硬化患者， 由于与改变的肠道微生物群相关的次级胆汁酸增加，发展增强的肠道和全身炎症。将使用这两个特定目的来检验该中心假设：特定目的1：使用系统生物学方法，与戒酒的酒精性戒酒者和非酒精性戒酒者相比，确定继发胆汁酸对持续酒精滥用的戒酒患者的全身和肠道炎症、肠道微生物组和内毒素血症的影响。我们将在100名受试者中使用系统生物学方法研究BA与十二指肠、回肠、结肠和粪便来源的微生物组与年龄和水肿严重程度匹配的主动饮酒者的全身性和肠壁炎症的相互作用，并与戒酒酒精性饮酒者、NAFLD患者和健康对照者进行比较。具体目标二：在无菌小鼠模型中，确定胆汁酸和肠道微生物群在酒精中毒患者粪便定植后肠道和全身炎症增加、内毒素血症和细菌移位发病机制中的作用。我们将利用无菌小鼠来阐明胆汁酸和微生物群对内毒素血症、炎症和细菌移位的个体贡献。将使用六组无菌小鼠：1）无干预，2）仅喂食脱氧胆酸，3）用健康人粪便定殖，4）用酒精性腹泻粪便定殖。将评价每组的肠道和全身炎症、内毒素血症、BA特征（血清、胆囊、肝脏、粪便、肠内容物），并在定植后进行微生物组变化（第3-4组），并在组间进行比较。这些研究将提供一个新的综合平台，使用尖端的转化和系统生物学方法研究次级胆汁酸和肠道微生物群在所有腹泻患者肠道和全身炎症发展中的作用。我们希望这项提案的结果能增加我们对发展重点治疗方法的洞察力，使这一服务不足的退伍军人群体受益。

DESCRIPTION (provided by applicant): Alcoholic liver disease and cirrhosis are one of the leading causes of morbidity and mortality in the US, as well as in the VA Health System. However, despite several programs to prevent and treat alcohol abuse, a significant proportion of affected Veterans continue to drink, even in the setting of cirrhosis. This can lead to a substantial burden that stems from an unchecked inflammatory milieu and endotoxemia due to bacterial translocation that precipitates infections, multi-organ failure and death. These patients are poor candidates for abstinence pharmacological therapy, are often non-adherent and cannot be offered liver transplant due to their continued drinking. Therefore prevention of this unchecked inflammation and bacterial translocation is critical; however, the exact mechanisms behind these are unclear, which is a major gap in our knowledge. Bile acids (BAs) and gut microbiota are key components of the intestinal milieu, whose interaction impacts bacterial translocation and inflammation. Our group has focused on delineating the role of microbiota, using culture- independent analyses, with inflammation and their modulation by BAs, especially the membrane-destabilizing secondary BAs in cirrhosis. We also discovered that actively drinking cirrhotics have a highly significant increase in fecal secondary BAs and intestinal inflammatory cytokine expression that may mediate intestinal injury and potentiate inflammation in these patients. Therefore, the study of the role of secondary BAs in the pathogenesis of intestinal and systemic inflammation in the context of altered gut microbiota or dysbiosis, in actively drinking cirrhotics compared to abstinent alcoholic cirrhotics and cirrhotics with non-alcoholic liver disease is critical in delineating the role of the intestinal milieu in the progression of liver disease. Our central hypothesis: Patients with cirrhosis, especially alcoholic cirrhotic patients who continue to drink, develop enhanced intestinal and systemic inflammation due to an increase in secondary bile acids associated with altered gut microbiota. This central hypothesis will be tested using these two specific aims: Specific aim 1: To define the effect of secondary bile acids on systemic and gut inflammation, gut microbiome and endotoxemia in cirrhotic patients with continued alcohol abuse compared to abstinent alcoholic cirrhotics and non-alcoholic cirrhotics using a systems biology approach. We will study the interaction of BAs with microbiome of the duodenal, ileal, colonic and fecal origin with systemic and intestinal wall inflammation in age- and cirrhosis-severity matched actively drinking cirrhotics compared to abstinent alcoholic cirrhotics, cirrhotic with NAFLD and healthy controls using a systems biology approach in 100 subjects. Specific Aim 2: To define the role of bile acids and gut microbiota in the pathogenesis of the increased intestinal and systemic inflammation, endotoxemia and bacterial translocation in a germ-free mouse model after colonization with stool from alcoholic cirrhotic patients. We will be utilizing germ-free mice to elucidate the individual contributions of bile acids and microbiota on endotoxemia, inflammation and bacterial translocation. Six groups of germ-free mice will be used: 1) without intervention 2) fed deoxycholic acid alone 3) colonized with healthy human stool 4) colonized with alcoholic cirrhotic stool. Each group will be evaluated for intestinal and systemic inflammation, endotoxemia, BA profile (serum, gallbladder, liver, fecal, intestinal contents) and microbiome changes (Groups 3-4) will be performed after colonization and compared between groups. The studies will provide a novel integrative platform to study the role of secondary bile acids and gut microbiota in the development of intestinal and systemic inflammation in all cirrhotic patients using cutting-edge translational and systems biology approaches. We expect the results of this proposal to increase our insight into the development of focused therapeutic approaches that benefit this underserved population of Veterans.