The Correlation Between Gut Microbiota-bile Acid-liver Metabolism Axis And NAFLD And The Intervention Effect Of Qingzhuan Tea

Background With the global prevalence of obesity and metabolic syndrome,non-alcoholic fatty liver disease(NAFLD)has become one of the global chronic liver diseases,and the incidence is increasing year by year,seriously affecting the healthy life of human beings.Objective To study the effect of Qingzhuan tea(QZT)on NAFLD through the correlation between gut microbiota-bile acid-liver metabolism axis and NAFLD.Methods C57BL/6 mice were randomly divided into 5 groups,normal control group(NC),model control group(MC),positive drug control group(PC),low-dose group(LD)and high-dose group(HD)of QZT water extract.A NAFLD model was established by feeding mice with high-fat diet for 14 weeks,and supplemented with low and high doses of QZT water extract and positive drug(Xuezhikang)preventively.(1)Routine indicators including the body weight,food intake,food utilization efficiency,liver weight and liver index of mice were determined.(2)Liver tissue pathological sections were observed by HE staining and Oil Red O staining.(3)Biochemical analysis indicators including TC,LDL-C,HDL-C,ALT content were detected.(4)The changes of gut microbiota were analyzed by high-throughput sequencing in 16 S rDNA V3-V4 region of mice feces.(5)The changes of serum bile acid were determined by LC/MS-MS targeted metabolomics method.(6)Spearman's correlation analysis was used to analyze the correlation between gut microbiota,bile acid and NAFLD.(7)The expression of liver tissue TGR5,NLRP3,Pro-caspase-1,Caspase-1 p10 protein were detected by Western blot.(8)ELISA method was used to detect changes in liver tissue IL-1?and IL-18.Results(1)There was no significant difference in the average food intake of mice in each group.Compared with normal control group,the body weight,food utilization efficiency,liver weight and liver index of model group increased significantly.Compared with model group,the above indicators of QZT water extract intervention groups were significantly reduced.(2)The liver tissue pathological section results showed that the liver tissues of mice in model group had fat accumulation and inflammation,and the degree of liver disease in QZT water extract intervention groups was improved.(3)The results of biochemical analysis showed that compared with normal control group,the contents of TC,LDL-C/HDL-C and ALT in model group were significantly increased.Compared with model group,the above indicators of QZT water extract intervention groups were significantly reduced.(4)The results of the gut microbiota analysis showed that the overall structure and abundance of the gut microbiota of model group were significantly different from those of the normal control group.LEf Se result showed five different floras.Among them,compared with normal control group,the abundance of Bacteroides in model group increased,and the abundance of Lactobacillus,Alloprevotella,Saccharibacteria?genera?incertae?sedis,and Ruminococcaceae in model group decreased.Compared with model group,the abundance of Bacteroides in QZT water extract intervention groups decreased,and the abundance of Lactobacillus,Alloprevotella,and Saccharibacteria?genera?incertae?sedis in QZT water extract intervention groups increased.(5)The results of bile acids analysis showed that a total of 23 bile acids were identified,including 10 primary bile acids and 13 secondary bile acids.17 differential bile acids were screened.Compared with normal control group,the differential bile acids abundance of model group relatively decrease,compared with model group,the abundance of the differential bile acids in QZT water extract intervention groups increased to varying degrees.(6)Correlation analysis results showed that the gut microbiota and bile acids were related to NAFLD,among which the most correlated floras were Bacteroides and Lactobacillus,and the most correlated metabolites were DCA and ?MCA.(7)Western blot results showed that compared with normal control group,the expression of TGR5 protein in the liver tissue of model group was significantly reduced,and the expression of NLRP3,Pro-caspase-1,and Caspase-1 p10 protein were significantly increased;compared with model group,the expression of TGR5 protein of QZT water extract intervention groups increased significantly,and the expression of NLRP3,Pro-caspase-1,and Caspase-1 p10 protein of QZT water extract intervention groups decreased significantly.(8)ELISA results showed that compared with normal control group,IL-1? and IL-18 in model group were significantly increased;compared with model group,IL-1? and IL-18 in QZT water extract intervention groups were significantly decreased.Conclusion(1)After 14 weeks of high-fat diet and QZT water extract intervention,the results of conventional indicators,histomorphology and biochemical analysis indicate that QZT has curative effect on the mouse NAFLD model.(2)Gut microbiota and its metabolites bile acids are related to NAFLD.Among them,the most correlated gut microbiota are Bacteroides and Lactobacillus,and the most correlated metabolites are DCA and ?MCA.Bile acids negatively regulate the NLRP3 inflammasome by binding to its liver receptor TGR5,so as to achieve the effect of reducing NAFLD.(3)QZT has an anti-NAFLD effect by regulating the gut microbiota-bile acid-liver axis.