三氯生暴露加剧高脂饮食诱导的小鼠肠道和肝脏功能损伤

Triclosan Exposure Exaggerates Injury of Intestine and Liver Function In-duced by High Fat Diet in Mice

三氯生(triclosan,TCS)在环境中被广泛检出,已成为重要的环境污染物,且TCS暴露能够影响机体的肠道菌群组成和脂类物质代谢过程。为了探讨TCS暴露对高脂饮食(high fat diet,HFD)诱导的肝脏功能损伤的影响及其机制,C57BL/6J小鼠随机分为正常饮食对照组、TCS组、HFD组和HFD+TCS组;首先对TCS组和HFD+TCS组小鼠进行提前一周TCS(10μg·g-1饲料)暴露,然后再同时进行6周的TCS暴露和HFD喂养。实验结束后,利用细菌特征序列对肠道菌群进行绝对定量分析,利用苏木精-伊红染色、实时荧光定量PCR、酶联免疫吸附测定、蛋白免疫印迹和流式细胞术等试验技术检测小鼠肠道和肝脏等生理变化状况。与对照组相比,TCS暴露和高脂饮食均能明显引起肠道菌群中厚壁菌门和拟杆菌门含量降低,同时引起小鼠脾脏中CD8+和CD4+T细胞比例失调,但未导致显著的肠道屏障损伤和脂多糖(lipopolysaccharide,LPS)异位;高脂饮食能够显著提高小鼠血清中丙氨酸氨基转移酶(alanine aminotransferase,ALT)、天门冬氨酸氨基转移酶(aspartate aminotransferase,AST)和甘油三酯(triglyceride,TG)的水平,而单独TCS暴露并没有引起明显的肝脏功能紊乱。与HFD组相比,HFD和TCS协同作用激活了小鼠肝脏中Toll样受体4(toll-like receptor 4,TLR4)炎症通路,造成小鼠肝脏炎症反应,并显著提高了小鼠ALT和AST水平,加剧了高脂饮食对小鼠肝脏功能的损伤。由此可知,TCS暴露通过引起小鼠肠道菌群紊乱和机体免疫响应,加剧高脂饮食诱导的小鼠肠道损伤和肝脏功能紊乱。

Triclosan(TCS)as an antimicrobial ingredient,is commonly added into the consumer products,such as soaps,toothpastes,cosmetics and other daily necessities.Due to the massive usage in daily life,TCS has been widely detected in the environment especially rivers and lakes.TCS exposure affected the composition of gut microbiota and disturbed the lipid metabolism process in aquatic organisms and murine models.In order to investigate the effect of TCS exposure on liver function injury induced by high fat diet(HFD),we constructed a mice model fed with HFD.After adaptation to the specific pathogen free(SPF)environment for one week,these C57BL/6J mice were randomly divided into 4 groups,the control group fed with normal chow,TCS group fed with normal chow containing TCS(10μg·g-1 diet),HFD group fed with HFD,HFD+TCS group fed with HFD containing TCS.The group of TCS and HFD+TCS were firstly exposed to TCS by feeding normal chow with TCS for one week,then the group of HFD was fed with HFD and HFD+TCS group was fed with HFD containing TCS,and the whole experiment last for another 6 weeks.At the end of the experiment,the abundance of Firmicutes,Bacteroidetes and Enterobacteriaceae were quantitated by real-time quantitative PCR(RT-qPCR)based on the bacterial characteristic sequences.Physiological changes in the murine intestine and liver tissues were characterized by H&E staining,RT-qPCR,ELISA,Western blotting and flow cytometry.Compared with the control group,the treatment of TCS and HFD significantly reduced the contents of Firmicutes and Bacteroidetes and increased the abundance of Enterobacteriaceae in the gut microbiota,but caused no significant intestinal barrier damage and could not promote the lipopolysaccharide(LPS)translocation from the intestinal tract into the circulatory system.In addition,TCS exposure and HFD also caused the imbalance of CD8+and CD4+T cells in the spleen of mice.Moreover,the HFD treatment significantly increased alanine aminotransferase(ALT),aspartate aminotransferase(AST)and triglyceride(TG)levels in mice,while single TCS exposure did not cause significant liver dysfunction.Compared with the HFD group,the combination of HFD and TCS activated the Toll-like receptor 4(TLR4)protein and promoted the inflammatory responses in the liver of mice,which significantly increased the levels of ALT and AST and aggravated the injury of the liver function caused by the HFD.In conclusion,TCS exposure can exacerbate intestine and liver dysfunction induced by HFD via disordering the gut microbiota and body immunity,and promoting liver inflammation.