Molecular and Genetic Analysis of Murine Steatohepatitis

描述（由申请人提供）：非酒精性脂肪性肝炎（NASH）是美国最常见的肝病原因之一，占隐源性肝硬化的大多数。NASH与包括胰岛素抵抗、肥胖和血脂异常的“代谢综合征”相关。此外，最近的证据表明，脂肪性肝炎的易感性和进展有很强的遗传成分。不幸的是，对NASH发病机制的遗传因素仍然知之甚少。NASH是一种多基因疾病，定量性状基因座（QTL）分析是一种广泛使用的遗传技术，其可应用于鼠模型以确定负责复杂性状和多基因疾病表达的染色体基因座。给小鼠喂食蛋氨酸-胆碱缺乏（MCD）饲料可作为进行性纤维化脂肪性肝炎的动物模型。因此，具体目标1将采用甲硫氨酸-胆碱缺乏（MCD）饲料来鉴定脂肪肝炎易感和脂肪肝炎抗性小鼠品系;并利用QTL分析来鉴定与脂肪肝炎相关的遗传基因座。NASH还与代谢综合征相关，并且给小鼠喂食高脂肪、高热量（HFHC）饮食是肥胖、代谢综合征和肝脂肪变性的充分表征的模型。然而，在喂食HFHC饮食的小鼠中肝损伤的分子机制仍然知之甚少。因此，特定目标2将采用高脂肪、高热量（HFHC）饮食来确定导致肝病易感性的遗传基因座和信号通路。对于非酒精性脂肪肝疾病的发病机制很重要的候选基因可以从肝脏炎症和代谢信号通路中鉴定出来;特别是如果它们在疾病敏感和疾病抗性小鼠中差异表达。类似地，人类遗传学研究中与NASH相关的基因也可以作为候选基因。因此，具体目标3将采用候选基因方法来鉴定在脂肪性肝炎和脂肪变性发病机制中重要的致病基因。本申请利用了两种互补的肝脂肪变性和脂肪性肝炎模型，以及最先进的遗传和分子生物学技术，以提高我们对脂肪性肝炎发病机制的理解。这种对脂肪性肝炎病理生理机制的深入了解将有助于设计合理的治疗方法来治疗这种影响数百万美国人的肝病。公共卫生相关性：非酒精性脂肪性肝炎（NASH）是美国肝脏疾病最常见的原因之一，尽管其发病机制仍然知之甚少。这些具体目标将采用脂肪变性和脂肪性肝炎的两种互补模型，并利用最先进的遗传和分子生物学技术，以增强我们对脂肪性肝炎发病机制和NASH易感性的理解。对NASH发展和进展的病理生理机制的理解将允许设计这种影响数百万美国人的常见肝病的合理治疗。

DESCRIPTION (provided by applicant): Non-alcoholic steatohepatitis (NASH) is one of the most common causes of liver disease in the United States, and accounts for the majority of cryptogenic cirrhosis. NASH is associated with the "metabolic syndrome", which includes insulin-resistance, obesity, and dyslipidemia. In addition, recent evidence indicates that there is a strong genetic component for the susceptibility and progression of steatohepatitis. Unfortunately, the genetic factors responsible for the pathogenesis of NASH remain poorly understood. NASH is a polygenic disease, and Quantitative Trait Loci (QTL) analysis is a widely utilized genetic technique that can be applied to murine models in order to determine the chromosomal loci responsible for the expression of complex traits and polygenic diseases. Feeding mice a methionine- choline deficient (MCD) diet serves as an animal model for progressive, fibrosing steatohepatitis. Thus, Specific Aim 1 will employ a methionine-choline deficient (MCD) diet to identify steatohepatitis-susceptible and steatohepatitis-resistant strains of mice; and utilize QTL analysis to identify the genetic loci associated with steatohepatitis. NASH is also associated with the metabolic syndrome, and feeding mice a High Fat, High Calorie (HFHC) diet is a well-characterized model for obesity, the metabolic syndrome, and hepatic steatosis. However, the molecular mechanisms of hepatic injury in mice fed a HFHC diet remain poorly understood. Thus, Specific Aim 2 will employ a High Fat, High Calorie (HFHC) diet to determine the genetic loci and signaling pathways that account for the hepatic disease susceptibility. Candidate genes that are important for the pathogenesis of nonalcoholic fatty liver disorders can be identified from hepatic inflammatory and metabolic signaling pathways; particularly if they are differentially expressed in disease-sensitive and disease-resistant mice. Similarly, genes associated with NASH in human genetic studies can also serve as candidate genes. Therefore, Specific Aim 3 will employ a candidate gene approach to identify causative genes that are important in the pathogenesis of steatohepatitis and steatosis. This application utilizes two complementary models of hepatic steatosis and steatohepatitis, and state-of-the-art genetic and molecular biological techniques, in order to enhance our understanding of the pathogenesis of steatohepatitis. This enhanced understanding of the pathophysiologic mechanisms responsible for steatohepatitis will allow for the design of rational therapies for this hepatic disease that affects millions of Americans. PUBLIC HEALTH RELEVANCE: Non-alcoholic steatohepatitis (NASH) is one of the most common causes of liver disease in the United States, although the pathogenesis remains poorly understood. These specific aims will employ two complementary models of steatosis and steatohepatitis, and utilize state-of-the-art genetic and molecular biological techniques, in order to enhance our understanding of the pathogenesis of steatohepatitis and susceptibility to NASH. An understanding of the pathophysiologic mechanisms responsible for the development and progression of NASH will allow for the design of rational therapies of this common hepatic disease that affects millions of Americans.