Molecular and Genetic Analysis of Murine Steatohepatitis

描述(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，也是隐源性肝硬变的主要原因。NASH与“代谢综合征”有关，包括胰岛素抵抗、肥胖和血脂异常。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，导致NASH发病的遗传因素仍然知之甚少。NASH是一种多基因疾病，数量性状基因座(QTL)分析是一种广泛应用的遗传技术，可应用于小鼠模型，以确定负责复杂性状和多基因疾病表达的染色体基因座。以蛋氨酸-胆碱缺乏(MCD)饮食喂养小鼠是进行性、纤维性脂肪性肝炎的动物模型。因此，特定目标1将使用蛋氨酸-胆碱缺乏(MCD)饮食来识别脂肪性肝炎易感和抗脂性肝炎小鼠品系；并利用QTL分析来识别与脂肪性肝炎相关的遗传位点。NASH也与代谢综合征有关，给小鼠喂食高脂肪、高热量(HFHC)饮食是肥胖、代谢综合征和肝脏脂肪变性的典型模型。然而，喂食HFHC饮食的小鼠肝脏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位点和信号通路。对于非酒精性脂肪性肝病的发病机制至关重要的候选基因可以从肝脏炎症和代谢信号通路中识别出来；特别是如果它们在疾病敏感和抗病小鼠中差异表达的话。同样，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，特定目标3将使用候选基因方法来识别在脂肪性肝炎和脂肪变性的发病机制中重要的致病基因。这一应用利用了肝脏脂肪变性和脂肪性肝炎两种相辅相成的模型，以及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的理解。对脂肪性肝炎的病理生理机制的进一步了解将有助于为这种影响数百万美国人的肝病设计合理的治疗方法。公共卫生相关性：非酒精性脂肪性肝炎(NASH)是美国最常见的肝病原因之一，尽管其发病机制仍然知之甚少。这些特定的目标将采用脂肪变性和脂肪性肝炎两种互补的模型，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的发病机制和NASH易感性的理解。对NASH发生和发展的病理生理机制的了解将有助于为这种影响数百万美国人的常见肝病设计合理的治疗方法。

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.