何首乌醇提物对脂多糖诱导大鼠肝TLR4/TRIF/IRF-3信号通路的影响

Effect of ethanol extracts from Polygonum multiflorum Thunb on expressions of signal pathway TLR4/TRIF/IRF-3 in LPS induced rats liver

目的研究大鼠经革兰阴性菌外膜成分脂多糖(LPS)诱导后,何首乌醇提物(PMT)对大鼠的肝毒性,并探讨其肝损伤机制与固有免疫炎症信号通路Toll样受体4(TLR4)-干扰素调节因子3(IRF-3)的关系。方法雄性SD大鼠随机分为正常对照组、对乙酰氨基酚(APAP,625 mg/kg)组、PMT 6 g/kg(PMT-L)和12 g/kg(PMT-H)组、脂多糖(LPS,4 g/L)组、(LPS+APAP)和(LPS+PMT-L/-H)组。后4组经尾静脉注射LPS 4 mg/kg,2 h后各实验组分别灌胃给予相应药物每日1次,连续7 d。观察每日大鼠体质量变化,分别在给药结束后2 h、14 h、5 d和8 d经HE染色检测大鼠组织形态变化,采用实时荧光定量PCR(RT-q PCR)法及Western印迹法检测肝细胞中TLR4信号通路干扰素TIR结构域衔接蛋白(TRIF)、IRF-3的表达情况。结果大鼠尾静脉注射LPS诱导后2 h,肝实质出现微小肉芽肿,其后,LPS组大鼠肝损伤逐渐恢复。诱导第8天时,LPS组大鼠肝组织结构清晰完整,LPS+APAP组和LPS+PMT各剂量组肝细胞灶状坏死,伴炎细胞浸润。RT-q PCR检测法和Western印迹法检测结果显示,单独灌胃何首乌醇提物的大鼠肝细胞中TLR4、TRIF和IRF-3的m RNA和蛋白表达水平与正常组相比无显著差异,而经LPS诱导的大鼠肝细胞TLR4、TRIF和IRF-3 m RNA和蛋白表达水平显著高于正常对照组,与LPS组相比有显著性差异(P<0.05),但PMT各剂量组间相比无显著差异。结论何首乌醇提物经LPS诱导能引起肝损伤,其引起的肝毒性与正性调控TLR4/IRF-3信号通路的表达有关,其肝损伤程度与给药剂量无关,提示TLR4/IRF-3信号通路的激活是LPS诱导何首乌醇提物肝损伤的作用机制之一。

Objective To research the toxicity of ethanol extracts from Poylgonum multiflorum Thunb（PMT）induced by endotoxin of Gram-negative bacteria lipopolysaccharide（LPS）in rat liver,and then investigate the hepatotoxicity mechanisms of PMT on immune inflammatory signal pathway Toll-Like receptor 4（TLR4）-interferon regulated factor3（IRF-3）. Methods SD rats were randomly assigned into normal control,LPS（4 mg/kg）,acetaminophen APAP（625 mg/kg）,PMT 6 g/kg（PMT-L）,PMT 12 g/kg（PMT-H）,LPS＋APAP and LPS＋PMT-L/-H groups. The 4 groups later were injected LPS 4 mg/kg by caudal vein,after 2 h,the corresponding drugs were administered once a day for 7 consecutive days,respectively. The changes of weight of rats were observed every day. The tissue morphology of liver tissue of rats on 2 h,14 h,5 d,8 d after administration were detected by hematoxylin-eosin staining respectively. Real time quantitative PCR（RT-q PCR）method and Western blotting were used to detect the expression of TLR4,TRIF and IRF3 in the TLR4 signaling pathway in liver cells. Results Two hours after the rat tail vein injection of LPS,the liver tiny granulomas of rats could be observed in LPS-induced groups,and then,the liver injury of rats in LPS group was gradually recovered.Eight Days after LPS induction,the liver tissue structure of rats in LPS group was clear and complete,but in LPS ＋ APAP group and LPS ＋ PMT 6 or 12 g/kg groups,the focal necrosis of hepatocytes,with inflammatory cell infiltration could be observed. The results of RT-q PCR and Western blotting showed that in oral administration of PMT groups,the expression of TLR4,TRIF and IRF-3 m RNA and protein in the liver cells had no significant change compared with the normal control group. But in 4 groups induced with LPS,the expression of TLR4,TRIF and IRF-3 m RNA and protein in the liver cells were significantly higher than that of the normal control group and LPS group（P0.05）. Conclusion PMT can cause liver damage induced by LPS,the hepatotoxicity is related to the positive regulation of TLR4/IRF-3 signaling pathways,which is not related to the dosage of PMT. The results show that activating TLR4/IRF3 signaling pathway is one of the mechanisms of liver injury of PMT in rats induced by LPS.