Experimental Study On The Role Of Gut Microbiota And Proximal Jejunum In The Improvement Of Glucolipid Metabolism After Roux-en-Y Gastric Bypass

Part Ⅰ Experimental study on the role of gut microbiota in the improvement of glucolipid metabolism after Roux-en-Y gastric bypassBackground:Bariatric surgery is one of the most effective treatments for obesity combined with type 2 diabetes(T2D),but the mechanism remains unclear.Changes in gut microbiota induced by bariatric surgery have been associated with metabolic benefits.Objective:Our aim was to identify specific gut microbiota that may contribute to the improvement of glucolipid metabolism after Roux-en-Y gastric bypass(RYGB).Methods:Diabetic rats induced via a high-fat diet and low-dose streptozotocin administration were randomized to RYGB and sham surgery(SHAM)groups,and stool samples were collected at baseline and at postoperative week 8.The faecal microbiota was profiled using 16S ribosomal RNA(rRNA)gene sequencing.Additionally,we performed a case-control study of the gut microbial community profiles of T2D patients compared to those of healthy individuals(CONT)via 16S rRNA gene sequencing of mucosal-luminal interface samples collected from the ascending colon during colonoscopy.Results:RYGB significantly reduced the body weight and improved glucose tolerance and insulin sensitivity in diabetic rats.The RYGB group was postoperatively enriched for Bacteroidetes,Proteobacteria,Fusobacteria and Actinobacteria;whereas the SHAM group was enriched for Firmicutes and Verrucomicrobia.Based on the gut microbial patterns in the T2D patients,we found that the family Coriobacteriaceae within Actinobacteria might contribute to the beneficial effects of RYGB on T2D.Conclusions:RYGB significantly improves glucose metabolism and alters the gut microbiota.Moreover,the family Coiobacteriaceae may partly mediate the beneficial effects of RYGB on glucolipid metabolism and thus possibly contribute to the development of novel bacteria-based therapeutic approaches.PartⅡ I Experimental study on the role of proximal jejunum in the improvement of glucolipid metabolism after Roux-en-Y gastric bypassBackground:Epigenetic changes may play an important role in the development of obesity and diabetes mellitus.Studies show that RYGB has a remodeling effect on DNA methylation.The foregut theory suggests that the proximal intestinal tract plays an important role in the improvement of T2D after RYGB.Objective:Our aim was to study the possible role of proximal jejunum in the treatment of T2D rats in RYGB via the analysis of DNA methylation and transcriptome.Methods:The first batch of T2D rat models were established and divided into RYGB and SHAM groups.The analysis of DNA methylation and transcriptome were performed using methylated DNA immunoprecipitation sequencing(MeDIP-seq)and transcriptome sequencing(RNA-seq).The second batch of T2D rat model was established and the MassARRAY platform for DNA methylation analysis and real-time quantitative PCR(qPCR)were used to verify the results of high-throughput sequencing analysis.Results:The RNA-seq results showed that the genes differentially expressed in the two groups were significantly enriched in the GO biological processes associated with fatty acid metabolism and lipid transport.The results of MeDIP-seq showed that there were 1973 genes with a significant difference in the methylation of the known genes in the DNA promoter region(P<0.05 and the Foldchange>2).The Mogat3 in the proximal jejunum after RYGB was obviously hypermethylated in the promoter region and its transcription level was significantly reduced.The results of the high-throughput sequencing were validated via methylation quantitative analysis and qPCR in new set of samples.Conclusions:The highly methylated gene promoter region of Mogat3 in the proximal jejunum of rats after RYGB may inhibit transcription and play a role in the improvement of lipid and glucose metabolism after operation.