白藜芦醇通过SREBPs调节肝细胞脂代谢及其对非酒精性脂肪性肝病干预研究

Non-alcoholic fatty liver disease (NAFLD) is now the most common liver disease in China and possibly worldwide. Furthermore, the number of affected patients is growing rapidly, and the disease has reached epidemic proportions. Nonalcoholic steatohepatitis (NASH), a more serious form of NAFLD, can proceed to cirrhosis and even hepatocellular carcinoma. There are insufficient high-quality studies to precisely determine the proper treatment of NAFLD. The US Food and Drug Administration has not approved any medications for use specifically in NAFLD, and all medications should be considered experimental. Based on knowledge of the pathogenesis of the disease, multiple smaller human trials of reasonably good quality have suggested the effectiveness of multiple treatments. These include lifestyle modifications and nutritional supplements. However, there are no ideal measurements for prevention and treatment of patients with NAFLD. Resveratrol, a polyphenol found in plant products, has been shown to regulate many cellular processes and to display multiple protective and therapeutic effects. Several in vitro and in vivo studies have demonstrated the influence of resveratrol on multiple intracellular targets that may regulate metabolic homeostasis.Resveratrol exerts beneficial effects in the prevention and treatment of NAFLD through the modulation of lipid metabolism-related genes, such as sterol regulatory element-binding proteins (SREBPs),which is probably linked to resveratrol dependent SIRT1 or/and AMPK activation.We focus on lipid metabolism in patients with NAFLD, since resveratrol exerts an effect that mimics calorie restriction.Our hypotheses is that resveratrol treatment may improve biochemical and ultrasonographic features of liver steatosis in patients with NAFLD, and this improvement may be associated with modifications in lipid metabolism via SREBPs.The aim of this study is to investigate whether resveratrol improves the liver steatosis in vivo and in vitro through regulating lipid metabolism via SREBPs.Furthermore, this project will be conducted as a randomized controlled trail designed to evaluate whether resveratrol treatment improves biochemical and ultrasonographic features of liver steatosis in patients with NAFLD.

非酒精性脂肪性肝病（NAFLD）已成为全球主要公共卫生问题之一，我国成年人患病率约20%，且有发展成肝硬化甚至肝癌的风险，目前尚未发现防治NAFLD的理想措施。白藜芦醇是多酚类植物化合物，具有抗氧化、抗炎症、调节血脂、改善脂代谢和胰岛素敏感性等生物学作用。白藜芦醇是SIRT1和AMPK的激活剂，而SIRT1可使SREBPs去乙酰化、AMPK可使SREBPs磷酸化，导致SREBPs转录活性降低，从而抑制肝细胞脂肪合成，结合课题组前期研究发现SREBPs在NAFLD的发生发展过程中发挥重要作用，我们认为白藜芦醇将成为防治NAFLD的理想植物化合物。本项目通过建立大鼠NAFLD模型和肝细胞脂肪变模型，深入探讨白藜芦醇通过SREBPs调节肝细胞脂代谢而影响NAFLD发生发展的分子机制，同时采用随机对照试验研究白藜芦醇对NAFLD患者的人群干预效应，为防治NAFLD提供新的思路和科学依据。

非酒精性脂肪性肝病（NAFLD）已成为全球主要公共卫生问题之一，然而，至今尚未发现有效防治NAFLD的理想药物。已有报道认为白藜芦醇（RSV）具有缓解NAFLD的作用，但是其机制尚不清楚。本研究运用棕榈酸（PA）处理HepG2细胞建立肝细胞脂肪变性模型，用高脂膳食诱导建立小鼠NAFLD模型，应用油红O染色、TG含量分析、激光共聚焦、透射电镜等技术，结合使用自噬激动剂、自噬抑制剂和质粒转染，研究发现RSV可诱导肝细胞自噬而改善肝细胞脂肪蓄积；应用免疫印迹和PCR分析发现RSV能上调SIRT1、PRKA和pAMPK的表达，而使用PRKA、AMPK或SIRT1的抑制剂或者siRNA处理时，RSV介导的自噬被抑制，提示RSV能通过调控SIRT1相关信号通路而诱导自噬抑制肝细胞脂肪变性。RSV对高脂诱导的NAFLD大鼠的干预研究表明，RSV可能通过上调pAMPK和SIRT1表达，下调SREBP-1c、FAS等基因的表达与活性，减少肝脏TG含量，从而发挥其预防高脂膳食诱导大鼠NAFLD发生发展的作用。采用随机对照试验，发现每天600mg RSV干预三个月能改善NAFLD患者的炎症、胰岛素抵抗、脂代谢等，但对肝脏B超的影像学指标并无明显影响。从NAFLD人群干预、NAFLD动物模型和体外HepG2细胞培养三个层面研究证实RSV能够有效改善肝细胞脂肪变性，而Sirt1/SREBP-1c信号通路在RSV改善NAFLD方面发挥重要作用，为防治NAFLD提供了新的思路和科学依据。