Characterization Of Gut Microbiota And Gut Inflammation In Nonalcoholic Fatty Liver Disease Patients

BackgroundNonalcoholic fatty liver disease(NAFLD)is a kind of metabolic liver injury characterized by the excessive infiltration of liver fat.NAFLD has become the most common chronic liver disease.Recent studies showed that gut dysbiosis is associated with the occurrence and development in NAFLD.The gut dysbiosis is an important factor leading to gut inflammation,and gut inflammatory state in NAFLD has been rarely reported.The pathogenesis of dysbiosis and gut inflammation in NAFLD is worthy of further discussion.ObjectiveThis study is to identify the characterization of gut microbiota and gut inflammation in NAFLD.MethodsEighty-one NAFLD patients were enrolled at the outpatient of Nanjing General Hospital of Nanjing Military Region from May 2015 to August 2016,91 cases from Physical Examination Center were enrolled as healthy controls.Their serum and fecal samples were collected for biochemistry test and fecal calprotectin measurement by ELISA,respectively.Besides,among the fecal samples of participants,24 from NAFLD patients and 18 from healthy persons were used for 16SrRNA sequencing.Comparisons between two groups were tested with the independent samples T-test or X2 test for the enumeration data.Correlations between two continuous variables were performed by Spearman's correlation.Logistic regression was used in multivariate analyses.The statistical analyses were conducted using the SPSS 20 software.A P value<0.05 was regarded as statistically significant.Results1.Participant characteristics A significant increase was found in the body mass index(BMI),waist circumference,uric acid,fasting blood glucose,AST,ALT,GGT,TC,TG,and LDL in the NAFLD group compared with healthy controls.The NAFLD group had a lower concentration of HDL.Multivariate analysis showed that TG,HDL,BMI,and TC were independently associated with NAFLD.2.The composition of gut microbiota At phylum levels,Firmicutes,Bacteroides,Proteobacteria,and Actinobacteria represented more than 95%of gut microbiota in the two groups.A decrease in Bacteroidetes(30.46%VS 46.43%)and an increase in Proteobacteria(23.21%VS 7.99%)was observed in the NAFLD group,and the ratio of Proteobacteria to Bacteroidetes was higher in the NAFLD group than that in the control group(P<0.01).The abundance of Firmicutes and Actinobacteria were similar between the two groups.At family and genus levels,the abundance of Bacteroidaceae and Bacteroides decreased in the NAFLD group,and the abundance of Enterobacteriaceae and Escherichia,and the ratio of Escherichia to Bacteroides increased in the NAFLD group.3.Measurement of FC The average concentration of FC in the NAFLD group(43(18.8-87.0)?g/g)is higher than that in the control group 11.4(4.6-24.4)?g/g),P<0.001.There were correlations between FC and BMI,TC and GGT,and the correlation coefficients were 0.725(P<0.001),0.292(P = 0.010)and 0.400(P<0.01),respectively.4.Correlations analysis between FC concentrations and abundances of gut microbiota FC concentrations were positively correlated with the abundance of Escherichia(r = 0.644,P<0.001),and FC concentrations were negatively correlated with Bacteroides abundance(r = 0.426,P =0.038).Besides,FC concentrations were positively correlated with the ratio of Escherichia to Bacteroides(r = 0.810,P<0.001).ConclusionGut inflammation and gut dysbiosis were both present in the NAFLD patients.Gut inflammation might be related to gut dysbiosis characterized by increasing the ratio of Escherichia to Bacteroides.Gut dysbiosis and gut inflammation may be associated with the onset and development of NAFLD.