Proteomic profiling of NASH: disease mechanisms and novel treatment

描述（由申请方提供）：非酒精性脂肪性肝病（NAFLD）是一种多因素临床病理学疾病，其特征为肝细胞中显著的脂质蓄积。在一系列人群中，患病率范围为10-24%，高达58%的肥胖成年人和53%的肥胖儿童受这种疾病的影响。这种疾病向更晚期阶段（NASH）转变的潜在机制仍有待阐明，其特征在于脂肪肝、肝细胞死亡和纤维化，尽管氧化应激被认为在这种进展中起核心作用。氧化应激的特征在于产生活性氧（ROS），其引发脂质过氧化，产生脂质过氧化的生物活性代谢产物，包括4-羟基-2-壬烯醛（4-HNE）和4-氧代壬烯醛（4-ONE）。我们的工作假设是，4-HNE和4-ONE的特异性蛋白质修饰在NASH的发病机制中起重要作用。这一假设将通过三个具体目标提出的系统实验进行测试，使用饮食诱导的脂肪肝小鼠模型。目的1中的实验将建立NAFLD和NASH的记录的生物化学和代谢标志与肝氧化应激的机制关系，以描述4-HNE和4-ONE协调“第二次打击”的能力。在NAFLD和NASH的进展期间出现的待表征的参数包括肝组织病理学、胰岛素敏感性、脂质体内平衡失调、TNF-α产生增加、脂联素减少、促炎细胞因子过度产生以及炎症和纤维化。目的2中的实验将鉴定由4-HNE和4-ONE修饰的肝蛋白，目的是鉴定与NASH的起始和进展的机制联系。实验提出使用候选蛋白质，长链酰基CoA脱氢酶和ER应激调节剂GRP 78来评估与NASH相关产生的4-HNE和4-ONE对蛋白质修饰的功能后果。目标3中的新研究将采用蛋白质组学方法，通过恢复ER应激反应和保护TNF-α诱导的细胞死亡来评估牛磺酸补充剂在阻止NAFLD和NASH中的保肝机制。这些拟议的实验将为NAFLD的病理机制和治疗这种肝病的潜在治疗方法提供新的见解。

DESCRIPTION (provided by applicant): Nonalcoholic fatty liver disease (NAFLD) is a multifactorial clinicopathologic condition characterized by marked lipid accumulation in hepatocytes. The prevalence ranges from 10-24% across a spectrum of populations with upwards to 58% of obese adults and 53% of obese children affected by this disorder. The mechanisms underlying the transition of this disease to the more advanced stage, (NASH), characterized by hepatosteatosis, hepatocyte death and fibrosis remain to be elucidated although oxidative stress is proposed to play a central role in this progression. Oxidative stress is characterized by the production of reactive oxygen species (ROS) which initiate lipid peroxidation giving rise to bioactive aldehydic products of lipid peroxidation including 4-hydroxy-2-nonenal (4-HNE) and 4-oxononenal (4-ONE). It is our working hypothesis that specific protein modifications by 4-HNE and 4-ONE play important roles in the pathogenesis of NASH. This hypothesis will be tested by systematic experiments proposed in three specific aims using a mouse model of dietary-induced fatty liver. Experiments in Aim 1 will establish mechanistic relationships of documented biochemical and metabolic hallmarks of NAFLD and NASH with hepatic oxidative stress to delineate the ability of 4-HNE and 4-ONE to orchestrate the "second hit". Parameters to be characterized which emerge during the progression of NAFLD and NASH include hepatic histopathology, insulin sensitivity, dysregulation of lipid homoeostasis, increased production of TNF-a, decreases in adiponectin, the overproduction of proinflammatory cytokines as well as inflammation and fibrosis. Experiments in Aim 2 will identify hepatic proteins modified by 4-HNE and 4-ONE with the goal of identifying mechanistic links with initiation and progression of NASH. Experiments are proposed using the candidate proteins, long-chain acyl CoA dehydrogenase and the ER stress modulator GRP78 to evaluate the functional consequences of protein modification by 4-HNE and 4-ONE produced in association with NASH. Novel studies in Aim 3 will employ proteomic approaches to evaluate the hepatoprotective mechanisms of taurine supplementation in arresting NAFLD and NASH by restoration of ER stress response and protection against TNF-alpha-induced cell death. These proposed experiments will provide new insight into the pathomechanisms of NAFLD and potential therapeutic approaches to the treatment of this liver disease.