Olfactomedin 4在非酒精性脂肪性肝病中的作用及机制研究

Nonalcoholic fatty liver disease (NAFLD) is characterized by hepatic steatosis in the absence of a history of significant alcohol use or other known liver disease.The pathogenesis of NAFLD has not been fully understood. Our previous study observed that olfactomedin 4 (Olfm4) is up-regualted in both cellular and mouse model of NAFLD, whereas siRNA-mediated knocking down of Olfm4 significantly attenuates free fatty acids-induced fat accumulation in HepG2 cells. These results suggest that Olfm4 may play an important role in the pathogenesis of NAFLD. Current study aims to further investigate the regulatory role and mechanism of Olfm4 in NAFLD. The expression of Olfm4 will be manipulated both in vivo and in vitro, and the functional consequences of these manipulations on the degree of hepatic steatosis, expression level of molecules involved in hepatic lipid metabolism and inflammatory response will be analyzed. The regulatory mechanisms of Olfm4 in NAFLD will also be investigated by microarray analysis, followed by qPCR validation and functional analysis. As the increasing prevalence of NAFLD, the results of this study will not only expand our understanding of the mechanisms of NAFLD, but also assist in the eventual development of new therapeutic targets for the disease.

非酒精性脂肪性肝病（NAFLD）是一种以肝细胞脂肪变性为特征的临床病理综合征，其发病机制目前尚未明确。Olfm4是近年来发现的一种具有多种生物学功能的糖蛋白。前期研究发现Olfm4与肥胖有关，且其表达水平在NAFLD细胞和小鼠模型肝脏中均显著上调，而敲低Olfm4表达则显著减轻软脂酸诱导的肝细胞脂肪变性程度，提示Olfm4对NAFLD具有调节作用，但其调节机制尚不清楚。本项目拟在已有基础上，建立NAFLD细胞及小鼠模型并结合Olfm4 基因敲除小鼠，运用siRNA和重组腺病毒技术抑制或增强Olfm4表达，在观察Olfm4表达变化对肝脏脂变和炎症影响的同时，通过Western Blot、qPCR等方法检测Olfm4表达改变对肝脏脂质代谢、炎症反应等相关分子的影响，并运用表达谱芯片筛选和验证Olfm4调节新靶点，以期明确Olfm4在NAFLD中的具体作用及机制，为NAFLD防治提供新线索。

本项目旨在探讨嗅素蛋白4(Olfm4)在非酒精性脂肪性肝病(NAFLD)中的作用及其机制。本项目采用游离脂肪酸刺激肝细胞建立NAFLD细胞模型，采用高脂饮食、胆碱和蛋氨酸缺乏饮食建立两种不同NAFLD小鼠模型。在构建Olfm4(-/-)小鼠的基础上，发现敲除Olfm4显著加重游离脂肪酸诱导的原代肝细胞脂质沉积，敲除Olfm4也显著加重高脂饮食、胆碱和蛋氨酸缺乏饮食诱导的小鼠肝脏脂肪变性和炎症程度。进一步研究发现，Olfm4可以通过影响肝脏巨噬细胞浸润、诱导内质网应激等途径调节肝脏糖脂代谢并影响NAFLD。本项目的实施，揭示了NAFLD发病新机制并为疾病防治提供了潜在新靶点。