降脂颗粒上调IRISIN信号通路治疗NAFLD的作用及机制研究

Non-alcoholic fatty liver disease (NAFLD) is a type of hepatic injury caused by metabolic stress, and this disease is closely related to insulin resistance and genetic susceptibility. The prevalence of NAFLD is increasing annually and shows low aging tendency. Thus the disease has become one of the world’s important public health problems in 21st century. IRISIN a newly discovered hormone-like myokine, could reduce the synthesis of lipid and cholesterol in NAFLD through AMPK, suggesting it to be a new target for prevention and treatment of NAFLD. Applied in treating NAFLD clinically for a long time, Jiangzhi granule (JZG) has been proved efficient in clearing heat and damp as well as removing phlegm and blood stasis. Our previous experiments confirmed that JZG could dramatically decrease serum lipid and ameliorate liver function in NAFLD rats. These functions may be related to IRISIN. Using animal and cell model of NAFLD, this project plans to observe the role of IRISIN-AMPKα1/ACC1 and IRISIN-AMPKα1/HMGCR on synthesis of fatty acid and cholesterol, as well as study the effect of JZG on IRISIN. This study will provide experimental basis to elucidate the potential mechanism of JZG in treating NAFLD.

非酒精性脂肪性肝病(NAFLD)是一种与胰岛素抵抗和遗传易感性密切相关的代谢应激性肝损伤。近年来，NAFLD患病率逐年上升且呈现低龄化趋势，已成为21世纪全球重要的公共健康问题之一。鸢尾素(IRISIN)是一种新发现的激素样肌因子，通过AMPK的介导，IRISIN可降低NAFLD中脂质与胆固醇的合成，是NAFLD防治的新靶点。降脂颗粒具有清热利湿、化痰消瘀之功效，长期应用于NAFLD的治疗。课题组前期研究提示降脂颗粒能够显著降低NAFLD大鼠的血脂水平、改善肝功能等，其作用机制可能与IRISIN通路有关。本课题通过制备NAFLD大鼠模型及细胞模型，观察信号通路IRISIN-AMPKα1/ACC1与IRISIN-AMPKα1/HMGCR对脂肪酸及胆固醇合成的影响，以及降脂颗粒对IRISIN信号通路的调节作用，为阐明降脂颗粒治疗NAFLD的机制提供实验依据。

目的：研究降脂颗粒治疗高脂饮食诱导的NAFLD动物模型的效应及其基于Irisin信号通路的作用机制与靶点。结果：1.高脂饮食成功制备了NAFLD大小鼠模型，肝脏HE染色及油红O染色显示，NAFLD大小鼠模型肝脏中出现了大量的脂肪沉积，肝脏中TG含量升高；NAFLD大小鼠血清肝功能和血脂的水平显著升高；降脂颗粒可显著改善NAFLD大鼠肝脏中脂肪沉积及血清肝功能、血脂等，其作用机制可能是通过调节NAFLD大小鼠肝脏中Irisin的表达，进而调控NAFLD大小鼠肝脏中脂肪与胆固醇的生成。2. Irisin可抑制3T3-L1前脂肪细胞成脂分化，上调白色脂肪棕色化相关因子与线粒体基因，下调脂肪细胞中脂肪生成相关因子mRAN的表达。3. Irisin可通过调节ACC与HMGCR mRNA与蛋白的表达降低脂肪变性的HepG2和AML12细胞中脂肪与胆固醇的生成，这一作用是通过AMPKα介导的。结论: 1. 降脂颗粒可通过上调NAFLD大小鼠肝脏中Irisin的表达，并通过调节Irisin-AMPKα-ACC与Irisin-AMPKα-HMGCR信号通路改善NAFLD大小鼠肝脏中脂质沉积。 2.Irisin可促进脂肪细胞转化为棕色脂肪细胞、降低脂肪细胞中脂肪生成并增加脂肪氧化，调节脂肪细胞能量代谢。3. Irisin可通过调节AMPKα降低脂肪变性的肝细胞中脂肪与胆固醇的生成，其机制是通过Irisin-AMPKα-ACC与Irisin-AMPKα-HMGCR信号通路实现。