基于STAT3-SOCS3通路研究新型PPARγ调控剂GVS-12对非酒精性脂肪肝炎的保护作用与机制

Nonalcoholic steatohepatitis (NASH) is a chronic hepatitis which is induced by insulin resistance and characterized by diffuse hepatic inflammation. PPARγ agonist rosiglitazone is the most effective drugs to improve insulin resistance and inhibit NASH, but it is limited to apply for clinical because of its many side effects. As the result of combining the advantage of structure features of rosiglitazone and SR1664, a modulating ligand of Peroxisome proliferator-activated receptors(PPARγ), and also avoiding the structure feature about side effect, we designed and synthetised a new type of modulating ligand of PPARγ, GVS-12. Preliminary results showed that GVS-12 has a significant role in suppressing NASH. So, GVS-12 how to suppress NASH, what is the molecular mechanism behind GVS-12? In the study, these methods of dual-luciferase reporter assay, western blot, Si RNA and so on will be used on NASH in vitro and vivo models in order to get the reliable evidences on inhibiting NASH, suppressing JAK-STAT3 inflammatory signaling pathway and explore its molecular mechanism. Furthermore, we confirm that SOCS3 is a negative regulatory protein of JAK-STAT3 signaling pathway that may become a new target toward treating NASH effectively. Our study is promising to reveal the mechanism of GVS-12 on inhibiting NASH and support to developing a new therapeutic intervention for NASH.

非酒精性脂肪肝炎（NASH）是一种以胰岛素抵抗为诱因，弥漫性肝脏炎症为主要特征的慢性肝脏炎症。PPARγ激动剂罗格列酮是改善胰岛素抵抗、抑制NASH的有效药物，但因诸多不良反应限制了临床应用。我们结合罗格列酮及PPARγ调控剂SR1664的结构特点，规避副作用产生位点，设计合成新型PPARγ调控剂GVS-12。前期结果表明，GVS-12具有改善NASH肝脏炎症作用。那么，GVS-12如何抑制NASH，其分子机制是什么？本项目中，我们拟以NASH体内外模型为研究对象，采用双荧光素酶报告基因、免疫印迹和Si RNA等方法，旨在获得GVS-12对NASH保护作用的可靠证据，探索其抑制炎症信号通路JAK-STAT3的分子机制;并进一步明确STAT3信号通路的负性调控蛋白SOCS3是否是治疗NASH的靶标。本项目有望揭示GVS-12对NASH的保护作用及机制，为开发治疗NASH的新药提供更充分依据。

非酒精性脂肪性肝炎（Non-alcoholic steatohepatitis, NASH）是一种脂肪肝疾病，其特征是肝脏过度发炎和脂肪堆积。核受体过氧化物酶增殖体受体-γ（Peroxosomal proliferator activated receptor γ, PPARγ）激动剂罗格列酮（Rosiglitazone）在改善NASH发生方面具有巨大潜力。但是，罗格列酮长期使用可能会导致许多不良反应，从而限制了其临床应用。本研究结合罗格列酮及PPARγ调控剂SR1664的结构特点，根据它们与PPARγ LBD晶体复合物作用形式，规避副作用的产生，设计合成新型PPARγ调控剂GVS-12，增加了PPARγ报告基因的活性和促进分化簇36（Cluster of differentiation 36, CD36）（PPARγ的靶基因）的mRNA表达。GVS-12可下调高脂饮食（high fat diet, HFD）诱导的NASH大鼠肝脏和棕榈酸（palmitic acid, PA）诱导的HepG2细胞中白细胞介素-1β（interleukin-1β, IL-1β），白细胞介素-6（interleukin-1β, IL-6）和肿瘤坏死因子-α（tumor necrosis factor-α, TNF-α）的mRNA表达，从而改善肝功能障碍和脂质蓄积。此外，PPARγ siRNA（siPPARγ）明显降低了GVS-12对PA刺激的HepG2细胞中IL-1β、IL-6和TNF-α mRNA表达的抑制作用。siPPARγ逆转了GVS-12降低信号传导及转录激活蛋白3（Signal transducer and activator of transcription 3, STAT3）的磷酸化水平和提高细胞因子信号转导抑制蛋白3（Suppressor of Cytokine Signaling 3, SOCS3）的蛋白表达。并且SOCS3 siRNA（siSOCS3）减弱了GVS-12对IL-1β、IL-6和TNF-α mRNA表达的抑制作用。综上所述，确定了GVS-12通过PPARγ/STAT3信号通路下调IL-1β、IL-6和TNF-α的mRNA表达来抑制NASH的发展。本研究有望为开发NASH的新药提供更充分的科学依据。