基于胆汁酸相关TGR5-cAMP信号通路探讨降脂颗粒对非酒精性脂肪性肝炎的调控机制

Non-alcoholic steatohepatitis (NASH) causes severe hepatic and metabolic risks in patients, but pharmacological strategies are limited. Traditional Chinese medicine is of significant effect in treating NASH, however, the mechanisms are remain unclear. The herbal compounds Jiangzhi granula developed by our group has been confirmed to be safe and effective in treating of fatty liver disease in a Phase II clinical trial. Mechanisms exploration in our previous studies revealed that bile acid G protein-coupled receptor TGR5 is up-regulated with the improvement of metabolic-related inflammation in Jiangzhi Granula treated animals. Therefore, based on the previous studies, we hypothesized that "Jiangzhi granula may treat NASH via activating TGR5". To verify the hypothesis, we intend to investigate the changes of TGR5-cAMP signaling pathway through both in vivo and in vivo experiments, high-throughput analysis, cell transfection and gene knockout technology, and demonstrate the potential mechanisms under the efficacy of Jiangzhi granula in regulating bile acid pool, lipid metabolism, metabolic inflammation, etc. our work are expecting to be valuable in promoting NASH prevention and treatment with Traditional Chinese Medicine.

非酒精性脂肪性肝炎（NASH）引起的肝脏和代谢危害日趋严重，但治疗手段有限。中医药治疗NASH效果显著，但作用机制尚不明确。课题组研制的新药降脂颗粒经II期临床试验证实对脂肪肝治疗安全有效，机制探索发现降脂颗粒抑制肝脏代谢性炎症与胆汁酸G蛋白偶联受体TGR5表达升高有关。因此在前期研究基础之上，我们提出“降脂颗粒活化TGR5治疗NASH”的学术假说。为验证这一假说，本项目拟采用体内外实验、高通量分析、细胞转染、基因敲除等手段，探索TGR5-cAMP信号通路相关分子在NASH相关组织的变化规律，阐明降脂颗粒活化TGR5调节胆汁酸平衡、脂质代谢、炎症反应等多途径治疗NASH的作用机理，预期研究结果对促进中医药防治NASH相关疾病的应用有重要价值。

非酒精性脂肪性肝炎（NASH）引起的肝脏和代谢危害日趋严重，但治疗手段有限。中医药治疗NASH效果显著，但作用机制尚不明确。课题组研制的新药降脂颗粒经II期临床试验证实对脂肪肝治疗安全有效，机制探索发现降脂颗粒抑制肝脏代谢性炎症与胆汁酸G蛋白偶联受体TGR5表达升高有关。因此，本项目聚焦胆汁酸受体TGR5研究降脂颗粒治疗NASH的药效机制。研究分别评价了降脂颗粒治疗高脂联合硫酸葡聚糖（HF-DSS）诱导NASH和蛋氨酸胆碱缺乏饮食诱导的NASH动物模型的药理效应，证实了降脂颗粒干预可改善肝组织脂肪变和炎细胞浸润、纠正血脂紊乱，降低炎性细胞因子表达。通过对NASH小鼠模型血清、肝脏和粪便中胆汁酸组分的分析，证实降脂颗粒可调节胆汁酸谱，影响肠道norDCA、α+ωMCA和LCA水平。次级胆汁酸是肠道菌群代谢产物，肠道中次级胆汁酸组分如LCA、DCA等均可激活胆汁酸受体FXR和TGR5，接下来我们评估了胆汁酸受体FXR和TGR5通路，发现肠道FXR和TGR5在两种小鼠模型中的表达均明显降低，降脂颗粒干预可明显上调MCD模型小鼠胆汁酸受体FXR和TGR5的表达，在HF-DSS小鼠降脂颗粒仅上调了肠道TGR5蛋白表达。降脂颗粒活化MCD诱导的NASH小鼠肠道FXR-FGF15通路促进FGF15分泌进入肝脏，以及活化TGR5通路参与炎症和代谢的调节。我们应用TGR5基因敲除小鼠验证了降脂颗粒作用的特异性。同时，体外建立TGR5过表达质粒也验证了TGR5-cAMP通路促进GLP-1分泌改善代谢以及抑制炎性细胞因子表达的效应。我们的研究从胆汁酸代谢和胆汁酸受体通路的角度系统探索了中药复方降脂颗粒的药效机制，发现中药复方对胆汁酸的活化是其对胆汁酸谱调节的次级效应，从而证实了内源性活化胆汁酸受体是中药复方效应的基础。因此，探索中药复方对NASH形成关键节点的内源性调控，是未来NASH预防和治疗的可行策略。