表没食子儿茶素没食子酸酯( EGCG) 对免疫性肝损伤的保护作用及其机制研究

目的:探讨表没食子儿茶素没食子酸酯(EGCG)对雷公藤甲素(TP)诱导的免疫性肝损伤的保护性作用及其作用机制。方法:雌性C57BL/6 小鼠随机分为4 组,即正常对照组、EGCG 对照组、TP 组、EGCG 治疗组。以赖氏法检测血清中ALT 水平,以分光光度法检测肝匀浆中丙二醛(MDA)、超氧化物歧化酶(SOD)和还原型谷胱甘肽(GSH)的变化情况,以HE染色观测小鼠肝脏组织形态学变化,以ELISA 方法检测肝脏中白细胞介素(IL)-17 和IL-6 的表达水平,以Western blot 方法检测肝脏中Toll 样受体4(TLR4)的表达情况。结果:TP 组小鼠血清转氨酶水平明显高于正常对照组(P<0.005),EGCG 对照组与正常对照组比较无变化(P>0.05),而EGCG 治疗组小鼠血清转氨酶水平与TP 组相比下降明显(P<0.005)。TP 组小鼠肝脏病理切片示较多肝细胞坏死和中性粒细胞浸润,EGCG 对照组和正常对照组小鼠肝脏形态学基本正常,EGCG 治疗组示肝细胞炎症坏死程度较TP 组有大幅减轻。TP 组小鼠肝脏中MDA、IL-17 及IL-6 水平明显高于正常对照组(P<0.005),而SOD和GSH 水平明显低于正常对照组(SOD,P<0.05;GSH,P<0.005),EGCG 对照组与正常对照组比较无变化(P>0.05),EGCG 治疗组小鼠肝脏中MDA、IL-17 及IL-6 水平均下降明显(P<0.005),而SOD 和GSH 水平均增高,与TP 组比较有显著性差异(SOD,P<0.05;GSH,P<0.005)。TP 组肝脏TLR4 蛋白表达水平高于正常对照组,EGCG 对照组与正常对照组比较无变化(P>0.05),而EGCG 治疗组TLR4 水平显著降低。结论:EGCG 对TP 所致小鼠肝损伤有明显的保护作用,可能与其抗氧化作用及对炎症因子的调节有关。

Study of protective effect of EGCG on immunological liver injury and relevant mechanism

Objective:To investigate the protective effect of Epigallocatechin-3-gallate (EGCG) on triptolide (TP)-induced immunological liver injuries,and explore the relevant mechanisms of action.Methods: A total of 40 female C57BL/6 mice were randomly divided into four groups: control group,EGCG group,TP group and TP+EGCG group.The ALT levels in serum was examined by Reitman Frankel method.The activity of hepatic MDA,SOD and GSH was examined by spectrophotometry.HE staining was used to observed the changes of the hepatic histopathology.The hepatic IL-17,IL-6 levels was examined by ELISA and the expression of hepatic TLR4 protein was examined by Western blot.Results: The results showed that serum alanine aminotransaminase (ALT) levels of TP group were obviously elevated (P<0.005,vs normal control group) and serum ALT levels were obviously reduced in EGCG treatment group(P<0.005,vs normal TP group).There were no significantly differences between EGCG group and control group (P>0.05). Meanwhile,EGCG could ameliorate hepatic pathological damage.Furthermore,in TP group,the activity of malondialdehyde (MDA),the expression of Toll-like receptor 4 (TLR4) protein and the contentration of hepatic interleukin (IL)-17,IL-6 were higher than normal control group (P < 0.005) .On the contrary,the activity of superoxide dismutase (SOD) and restored glutathione (GSH) were significantly lower than normal control group (SOD,P <0.05;GSH,P <0.005).In EGCG treatment group,the expression of TLR4 protein and the concentration of MDA,hepatic IL-17 and IL-6 were lower than TP group (TLR4,P<0.05;MDA,P<0.005;IL-17,P<0.005;IL-6,P<0.005).On the contrary,SOD and GSH were significantly higher than TP group (SOD,P<0.05;GSH,P<0.005). Conclusion: This study suggests that EGCG possesses hepatoprotective effect against TP-induced immunological liver injury through its anti-inflammatory and anti-oxidant actions.