Proteomic profiling of NASH: disease mechanisms and novel treatment

描述（由申请人提供）：非酒精性脂肪性肝病（NAFLD）是一种多因素的临床病理疾病，以肝细胞显著的脂质积累为特征。在人群中，患病率在10-24%之间，高达58%的肥胖成人和53%的肥胖儿童患有这种疾病。尽管氧化应激被认为在这一进展中起核心作用，但这种疾病向以肝骨坏死、肝细胞死亡和纤维化为特征的更晚期阶段（NASH）过渡的机制仍有待阐明。氧化应激的特征是产生活性氧（ROS），引发脂质过氧化，产生脂质过氧化的生物活性醛产物，包括4-羟基-2-壬烯醛（4-HNE）和4-氧壬烯醛（4-ONE）。我们的工作假设是，4-HNE和4-ONE的特异性蛋白修饰在NASH的发病机制中起重要作用。这一假设将通过在三个特定目的下提出的系统实验来验证，实验采用小鼠饮食性脂肪肝模型。目的1的实验将建立NAFLD和NASH的生化和代谢特征与肝脏氧化应激之间的机制关系，以描述4-HNE和4-ONE协调“第二次打击”的能力。在NAFLD和NASH进展过程中出现的特征参数包括肝脏组织病理学、胰岛素敏感性、脂质平衡失调、TNF-a的产生增加、脂联素的减少、促炎细胞因子的过度产生以及炎症和纤维化。Aim 2的实验将鉴定由4-HNE和4-ONE修饰的肝脏蛋白，目的是确定与NASH发生和进展的机制联系。研究人员建议使用候选蛋白、长链酰基辅酶a脱氢酶和内质网应激调节剂GRP78来评估与NASH相关的4-HNE和4-ONE对蛋白质进行修饰的功能后果。Aim 3的新研究将采用蛋白质组学方法来评估补充牛磺酸通过恢复内质网应激反应和保护tnf - α诱导的细胞死亡来抑制NAFLD和NASH的肝保护机制。这些拟议的实验将为NAFLD的病理机制和治疗这种肝脏疾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.