茶黄素双没食子酸酯对高脂饮食诱导小鼠肝脏损伤的影响及机制探讨

Effects of theaflavin-3,3'-digallate on high-fat diet-induced liver injury in mice and its mechanism

目的探讨茶黄素-3,3’-双没食子酸酯(theaflavin-3,3’-digallate,TFDG)膳食干预对高脂饮食诱导小鼠肝脏损伤的保护效应及相关机制。方法将C57BL/6小鼠按随机数字表法分为对照组(NC)、模型组(MC)、TFDG干预组(TF5和TF10),NC组喂食普通饲料,其余3组喂食高脂饲料,TF5和TF10组分别以5 mg/kg和10 mg/kg TFDG灌胃,NC和MC组以生理盐水灌胃,分组处理12周;检测小鼠肝指数、血清谷丙转氨酶(ALT)和谷草转氨酶(AST)水平,观察肝组织病理形态学变化,ELISA检测肝组织炎症因子水平,Western blot检测蛋白表达水平,qRT-PCR检测miR-223水平。结果高脂饮食诱导小鼠肝指数显著升高,血清ALT和AST水平明显上升,TFDG膳食干预可有效降低以上肝功指标(P<0.05);病理学观察表明,TFDG干预减少肝组织脂滴形成,脂含量检测结果也表明,TFDG干预显著降低肝组织TG和TC的含量(P<0.05);ELISA结果显示,高脂饮食诱导小鼠肝脏IL-1β、IL-6和TNF-α水平显著升高,TFDG干预可显著抑制肝脏炎症反应(P<0.05);Western blot检测结果显示,高脂饮食小鼠肝脏NLRP3、caspase-1和IL-1β的表达明显升高,TFDG干预可显著抑制NLRP3炎症通路激活(P<0.05)。TFDG干预可显著上调高脂条件下肝细胞miR-223的表达,以miR-223寡核苷酸抑制物阻断TFDG对miR-223表达的影响后,其对炎症反应的抑制作用显著降低(P<0.05)。结论TFDG可有效减轻高脂饮食诱导的肝脏损伤及炎症反应,其机制可能是通过上调miR-223抑制NLRP3通路实现的。

Objective To investigate the protective effects of dietary intervention with theaflavin-3,3'-digallate(TFDG)on liver injury induced by high-fat diet(HFD)in mice and its underlying mechanism.Methods Forty C57BL/6 mice were randomly and equally divided into normal control(NC),model control(MC)and TFDG administration(TF5 and TF10)groups.The mice of the NC group were fed with normal diet,and those of the other 3 groups were given HFD.Then the TF5 and TF10 groups were intragastrically given 5 mg/kg and 10 mg/kg TFDG respectively,while the NC and MC groups were treated with normal saline.After 12 weeks of intervention,the liver index,serum ALT and AST levels were detected,and the pathological changes of liver tissues were observed in the mice.The contents of inflammatory factors and the expression levels of related proteins in liver tissue were determined by ELISA and Western blotting respectively,and the mRNA level of miR-233 was measured by qRT-PCR.Results HFD significantly increased the liver index as well as serum ALT and AST levels,while these changes were effectively reversed by TFDG administration(P<0.05).Pathological observation displayed that TFDG intervention reduced the formation of lipid droplets in liver tissue,and lipid content detection also suggested that TFDG remarkably declined the levels of triglyceride(TG)and total cholesterol(TC)in liver tissue(P<0.05).ELISA indicated that the levels of IL-1β,IL-6 and TNF-αwere elevated notably in the liver of HFD-fed mice,and Western blotting confirmed higher protein levels of NLRP3,caspase-1 and IL-1β,whereas TFDG inhibited the inflammatory response of liver(P<0.05)and the activation of NLRP3/IL-1βpathway(P<0.05).In addition,TFDG intervention greatly up-regulated the expression of miR-223 in the hepatocytes under high-fat condition.After oligonucleotide inhibitor blocked the effect of TFDG on miR-223 expression,its inhibitory effect on inflammatory response was weakened as well(P<0.05).Conclusion TFDG can effectively alleviate liver injury and inflammatory response induced by HFD,which may be through up-regulation of miR-223 to inhibiting NLRP3 pathway.