Gut Microbiota Changes In Patients With Nonalcoholic Fatty Liver Disease

Objectives With the improvement of living standards,nonalcoholic fatty liver disease(NAFLD)has become one of the major chronic liver diseases in the world.NAFLD patients are often accompanied by obesity,metabolic syndrome,T2 DM,cardiovascular disease,the main cause of death is cardiovascular disease and metabolic syndrome-related tumors.Patients with nonalcoholic simple-fat hepatitis have a higher prevalence of cardiovascular disease than non-alcoholic simple fatty liver.Metabolic syndrome and T2 DM,on the other hand,are two major risk factors for NAFLD.Some even suggest that NAFLD is a manifestation of metabolic syndrome in the liver.Currently,it is generally believed that unhealthy lifestyles can lead to obesity and NAFLD,which is related to the disorder of intestinal flora caused by various environmental factors such as poor diet and habits.A growing number of related studies have found intestinal flora dysfunction by analyzing faeces of NAFLD patients.In addition,insulin resistance and inflammation often coexist with these conditions.Some scholars believe that the "second strike theory" is the main pathogenesis of NAFLD,eventually leading to chronic inflammation of the body state.More and more studies confirm that some gut flora have anti-inflammatory and anti-IR effects.However,limited to the sample size and individual heterogeneity,there is no clear and unanimous conclusion.Therefore,in this study,serum and stool specimens from NAFLD group,NAFLD combined with T2 DM group and healthy group were collected for clinical and biochemical detection and 16 S rDNA high-throughput illumina sequencing of intestinal flora,and to explore the relationship between intestinal microflora structure and biochemical changes in the relevance of NAFLD for the clinical diagnosis and prevention provide the basis.Methods Forty-eight NAFLD patients,forty NAFLD patients with T2 DM and thirty healthy subjects were enrolled in this study.All subjects were enrolled into the group by measuring the height,weight,waist circumference and other basic indicators,and calculate the BMI.Serum samples were collected from 5ml fresh fasting venous blood.The serum levels of FG,UA,TBIL,ALT,AST,TG,TC,HDL and LDL in all groups were detected by automatic biochemical analyzer.As well as FIns levels and calculate HOMA-IR values.Approximately 1 g of fresh stool samples were collected from each subject.DNA was extracted and the purity of DNA was detected by agarose gel electrophoresis.After PCR amplification,16 S rDNA high-throughput Illumina sequencing was used to sequence the diversity of intestinal flora.OTU clustering analysis and species taxonomy analysis were performed after comparing the optimized sequences.Results 1.Analysis of clinical biochemical indicators showed that the levels of BMI,AST,TG,TC,LDL,UA,TNF-?,FIns and HOMA-IR in NAFLD group were higher than those in healthy group,and the HDL level was lower than that in healthy group.The difference was statistically significant.(P<0.05).Compared with NAFLD group,NAFLD combined with T2 DM group had higher levels of age,FG,HOMA-IR,BMI,AST,TC and HDL levels,and the difference was statistically significant(P<0.05).2.The analysis of intestinal microflora diversity showed that compared with healthy group,the decrease of alpha diversity and the decrease of Firmicutes abundance in intestinal microflora of NAFLD patients.At genus level,the abundance of bacteria in Roseburia and Subdoligranulum genus in Firmicutes was decreased,with significant difference(P<0.05).At Phylum level,there was no significant difference in intestinal microflora between NAFLD patients with T2 DM and NAFLD(P>0.05),but the abundance of Firmicutes decreased and the abundance of Bacteroidetes increased.At genus level,the abundance of Faecalibacterium,Blautia and Roseburia genus in the Firmicutes gate of NAFLD combined T2 DM group were lower than that of NAFLD group and healthy group.3.According to Genus level,spearman correlation analysis showed that Fusicatenibacter,Blautia,Anaerostipes,Faecalibacterium,Roseburia all had negative correlation with FG and HOMA-IR(r<0,P<0.05);Fusicatenibacter was negatively correlated with TNF-?(P<0.05);Lachnoclostridium was positively correlated with BMI,ALT,AST(r> 0,P<0.05);Fusobacterium was positively correlated with AST(r> 0,P<0.05);Escherichia-shigella was positively correlated with the levels of FG,LDL,ALT and AST(r> 0,P<0.05).Conclusions1.NAFLD patients and NAFLD with T2 DM patients have chronic low-grade inflammation and insulin resistance,accompanied by obesity,hyperlipidemia and liver damage.2.NAFLD patients with intestinal flora disorder,manifested as reduced alpha diversity and decreased Firmicutes abundance.At genus level,abundances of the genera Roseburia and Subdoligranulum decreased.Fusicatenibacter,Blautia,Anaerostipes,Faecalibacterium,Roseburia and Lachnospiraceae are related to inflammation and insulin resistance.3.NAFLD interacts with gut flora and various environmental factors,and improving the IR and inflammatory response by regulating gut flora may serve as a new "target" for the prevention and treatment of NAFLD.