| Objective:To explore the changes of abundance,diversity and function of intestinal flora in rats with type 2 diabetes mellitus（T2DM）and diabetic nephropathy（DN）,and further analyze the correlation between the changes of intestinal flora and immune inflammation in order to comprehensively explore the imbalance pattern of intestinal flora in the two disease states.Methods:（1）The serum samples and colonic feces samples in this study were all from the model rats in the normal control group,type 2 diabetes group and diabetic nephropathy group previously constructed by the research team[1].（2）ELISA was used to detect the levels of lipopolysaccharide（LPS）,tumor necrosis factor-α（TNF-α）and monocyte chemoattractant protein-1（MCP-1）in the serum of rats in the three groups.（3）Amplicon sequencing was performed on the bacterial 16Sr DNA-V4 region of three groups of rat feces samples on the Ion S5TMXL platform,and biological information analysis was performed on the sequencing results.Results:（1）The results of serum inflammation indexes showed that the levels of serum LPS,TNF-αand MCP-1 of rats in the T2DM group and the DN group were higher than those of rats in the normal control group.The levels of serum LPS,TNF-αand MCP-1 in the DN group were significantly higher than those in the normal control group（P<0.05,P<0.01,P<0.01）,and the serum TNF-αlevel in the DN group was significantly higher than that in the T2DM group（P<0.01）.（2）α-diversity analysis showed that the intestinal flora diversity of rats in the T2DM group and the DN group was significantly higher than that in the normal control group（P<0.05）,but the difference in the measured number of species among the three groups was not statistically significant（P>0.05）.β-diversity analysis based on the weighted Unifrac distance showed that the difference in community structure of intestinal bacteria was low and there was significant similarity between the T2DM group and the DN group.（3）Compared with the normal control group,the abundance of Lachnospiraceae and Ruminococcaceae in the intestinal tract of rats in the T2DM group and the DN group was significantly increased（P<0.05）,while the abundance of Peptostreptococcaceae and Romboutsia was significantly decreased（P<0.05）.In addition,that abundance of Coriobacteriia and Coriobacteriales in the intestinal tract of rat in the T2DM group was significantly reduced as compare with that in the normal control group（P<0.05）,The abundance of Saccharimonadia,Saccharimonadales,[Eubacterium]＿coprostanoligenes＿group,Saccharimonadaceae,and Candidatus＿Saccharimonas was significantly increased（P<0.05）.The abundance of Firmicutes in the DN group was significantly lower than that in the normal control group（P<0.05）,while the abundance of Proteobacteria,Bacteroidetes,Enterobacteriae,Escherichia-Shigella and Ruminococcus was significantly increased（P<0.05）.Compared with the T2DM group,the abundance of Ruminococcus and Faecalibaculum in the intestinal tract of rats in the DN group was significantly increased（P<0.05）.（4）Spearman correlation analysis showed that Romboutsia had a significant negative correlation with LPS and MCP-1（P<0.05）,while Ruminococcus and Escherichia-Shigella had a significant positive correlation with LPS,TNF-αand MCP-1（P<0.05）.（5）Tax4Fun function prediction showed that compared with the normal control group,the number of intestinal flora involved in glycine and serine and threonine metabolism,biofilm formation Vibrio cholerae was increased in rats of T2DM group and DN group（P<0.05）,and the intestinal flora in the starch and sucrose metabolism,messenger RNA biosynthesis,photosynthetic protein,and photosynthesis was significantly decreased（P<0.05）.At the same time,the number of intestinal flora participating in lipid biosynthesis protein in rats of T2DM group was higher than that of the normal control group（P<0.05）,and the number of intestinal flora participating in glycerophospholipid metabolism was decreased（P<0.05）.The number of intestinal microflora participating in pyruvate metabolism in the DN group was larger than that in the normal control group（P<0.01）.Conclusion:（1）In two disease states of T2DM and DN,the imbalanced pattern of intestinal flora has the consistency and respective specificity.The composition of rat intestinal flora in the T2DM and DN model groups shifted to harmful bacteria,and more pathogenic changes were observed in the DN group than in the T2DM group.（2）Inflammation existed in the blood circulation of rats in the T2DM group and DN group,and the degree of inflammation in the blood of rats in the DN group was higher.The elevated serum inflammatory indices may be related to the decreased abundance of Romboutsia in the intestine.（3）The abundance of[Eubacterium]＿coprostanogens＿group and Candidatus＿Saccharimonas in the intestinal tract of rats in the T2DM group was increased,suggesting that intestinal fungal imbalance might also be one of the pathogenic mechanisms for the occurrence of T2DM.（4）The renal injury in T2DM and DN may be related to the presence of Faecalibaculum in the intestine and up-regulation of TNF-α-related signaling pathway.（5）The gene pathways of intestinal flora to glucose metabolism,amino acid metabolism and lipid metabolism were changed in rats of T2DM group and DN group. |
