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）是美国最常见的肝脏疾病之一，占隐源性肝硬化的大部分。NASH与“代谢综合征”有关，代谢综合征包括胰岛素抵抗、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，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，定量性状位点（QTL）分析是一种广泛应用的遗传技术，可以应用于小鼠模型，以确定负责复杂性状和多基因疾病表达的染色体位点。给小鼠喂食蛋氨酸-胆碱缺乏（MCD）饮食可作为进行性纤维化脂肪性肝炎的动物模型。因此，特异性目标1将采用蛋氨酸-胆碱缺乏（MCD）饮食来鉴定脂肪性肝炎易感和脂肪性肝炎抗性小鼠菌株；并利用QTL分析确定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、代谢综合征和肝脂肪变性的典型模型。然而，HFHC饮食对小鼠肝损伤的分子机制仍然知之甚少。因此，Specific Aim 2将采用高脂肪、高热量（HFHC）饮食来确定导致肝脏疾病易感性的基因位点和信号通路。非酒精性脂肪肝发病机制的重要候选基因可以从肝脏炎症和代谢信号通路中确定；特别是如果它们在疾病敏感型和抗病型小鼠中表达不同。同样，在人类遗传学研究中，与NASH相关的基因也可以作为候选基因。因此，Specific Aim 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。本应用程序利用肝脂肪变性和脂肪性肝炎的两种互补模型，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。对脂肪性肝炎病理生理机制的进一步了解将有助于设计合理的治疗方法，治疗这种影响数百万美国人的肝脏疾病。公共卫生相关性：非酒精性脂肪性肝炎（NASH）是美国最常见的肝脏疾病之一，尽管其发病机制尚不清楚。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。了解NASH发生和发展的病理生理机制将有助于设计合理的治疗方法，治疗这种影响数百万美国人的常见肝脏疾病。

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.