ABSTRACT
Objective@#To investigate the relationship between gut microbiota structure and biochemical changes in patients with different types of nonalcoholic fatty liver disease (NAFLD), in order to provide evidence for clinical diagnosis and prevention of NAFLD.@*Methods@#Forty-eight NAFLD cases (NAFLD group), 40 NAFLD cases with type 2 diabetes mellitus (NAFLD combined with type 2 diabetes mellitus group) and 30 healthy cases (healthy group) were randomly enrolled, and their body mass index, serum alanine aminotransferase, aspartate aminotransferase, total bilirubin, total cholesterol, triglyceride, high density lipoprotein, low density lipoprotein and uric acid were measured. Serum levels of TNF-alpha and fasting insulin were measured using ELISA, and then insulin resistance index was calculated. The gut microbiota of three groups of subjects was detected using 16S rDNA-based high-throughput sequencing. Lastly, the correlations between the various factors were analyzed. The comparison among groups was conducted by 2 test, and one-way ANOVA was used for comparison among groups with normal distribution and homogeneity of variance. Furthermore, the LSD method was used to compare the two groups. K-W rank sum test was used for comparison among groups without normal distribution or homogeneity of variance.@*Results@#Body mass index, aspartate aminotransferase, triglyceride, total cholesterol, low density lipoprotein, uric acid, tumor necrosis factor-alpha, fasting insulin and insulin resistance index of NAFLD group were higher than healthy group, while the high-density lipoprotein was lower in the healthy group, and the difference was statistically significant (P< 0.05). Compared with NAFLD group, the life expectancy, fasting blood glucose and insulin resistance index of NAFLD combined with type 2 diabetes mellitus group were higher, while the body mass index, aspartic acid aminotransferase, total cholesterol and HDL levels were decreased, and the difference was statistically significant (P< 0.05). NAFLD group (P= 0.016) had decreased abundance of firmicutes than healthy group, and the abundancy of the firmicutes in the NAFLD combined with type 2 diabetes group was significantly lower (P< 0.001). The abundance of bacteroidetes in NAFLD combined with type 2 diabetes group was higher than healthy group, and the difference was statistically significant (P= 0.006). At the "genus level," the abundance of Roseburia and Subdoligranulum in the NAFLD group was decreased, while the Roseburia in the NAFLD group with type 2 diabetes group was significantly lower (P< 0.05). In addition, the abundance of Faecalibacterium, Blautia, Anaerostipes and Fusicatenibacter in NAFLD combined with type 2 diabetes group was lower than healthy group, and the difference was statistically significant (P< 0.001). Fusicatenibacter, Blautia, Anaerostipes, Faecalibacterium, and Roseburia were negatively correlated with fasting blood glucose and insulin resistance index levels (r< 0,P< 0.05), and positively correlated with high-density lipoprotein levels (r> 0,P< 0.05). Fusicatenibacter was negatively correlated with tumor necrosis factor-alpha (r= -0.211,P= 0.044), and Lachnoclostridium was positively correlated with body mass index, alanine aminotransferase, aspartate aminotransferase levels (r> 0,P< 0.05). Fusobacterium was positively correlated with aspartate aminotransferase level (r= 0.245,P= 0.019). Escherichia-shigella was positively correlated with fasting blood glucose, low-density lipoprotein, alanine aminotransferase, aspartate aminotransferase levels (r > 0,P< 0.05). Megamonas was negatively correlated with high-density lipoprotein levels (r= -0.231,P= 0.027).@*Conclusion@#A structural change of gut microbiota had occurred in patients with NAFLD, suggesting changes in some of these bacterial genuses had relation to insulin resistance and inflammatory response, which may become a new target for the treatment of NAFLD.
ABSTRACT
Objective To investigate the effects of cholesterol-lowering probiotics, DM9054 com-bined with 86066, on the intestinal mucosal barrier and gut microbiota in mice with nonalcoholic fatty liver disease ( NAFLD) induced by high-fat diet and the possible mechanisms. Methods Twenty-four male mice deficient in the low-density lipoprotein receptor gene ( Ldlr- / - mice ) were randomly divided into three groups including control, NAFLD model and probiotic intervention groups. Mice in the three groups were given normal chow diet+normal saline, high-fat diet ( HFD)+normal saline, and HFD+cholesterol-lowering probiotics, respectively. The mouse model of NAFLD was established by feeding mice with high-fat diet (45％ of calories derived from fat diet) for 12 weeks. qPCR was performed to measure the expression of liv-er and intestinal inflammatory genes and liver cholesterol synthesis genes. Western blot assay was used to de-tect the expression of intestinal tight junction proteins and HMG-CoA reductase ( HMGCR ) . Pathological changes in tissues were evaluated by HE staining. Features of gut microbiota were analyzed by 16S rRNA gene sequencing. Results Cholesterol-lowering probiotics intervention attenuated HFD-induced hepatic steatosis, inflammatory responses and obesity and decreased the synthesis of liver cholesterol (P<0. 05). Moreover, inhibited gut inflammatory responses and improved intestinal barrier function were detected in the probiotic intervention group (P<0. 05). The composition of gut microbiota in mice of the probiotic intervention group was different from that of the model group, but similar to that of the control group. Con-clusions Cholesterol-lowering probiotics might attenuate NAFLD in mice through reducing liver cholesterol synthesis, alleviating liver and intestinal inflammation, improving intestinal mucosal barrier function and reg-ulating intestinal microbiota.