Role of microRNAs in the treatment of type 2 diabetes mellitus with Roux-en-Y gastric bypass

The aim of this study was to investigate the effect of Roux-en-Y gastric bypass (RYGB) on the peripheral blood microRNAs (miRNAs) of patients with type 2 diabetes mellitus (T2DM). miRNAs are small 20- to 22-nucleotide (nt) noncoding RNAs. They constitute a novel class of gene regulators that negatively regulate gene expression at the post-transcriptional level. miRNAs play an important role in several biological processes. Twelve patients with T2DM who were scheduled to undergo laparoscopic RYGB surgery were separated into two groups, using a body mass index of 30 kg/m2 as a cut-off point. Venous blood was collected before operation and 12 months after operation. A significant change was observed in the peripheral blood miRNA expression profile of both groups after RYGB surgery compared with those before operation. The expression levels of hsa-miR-29a-3p, hsa-miR-122-5p, hsa-miR-124-3p, and hsa-miR-320a were downregulated. The methylation state of the CpG sites within an approximately 400-bp genomic DNA fragment of each of the four miRNA genes, including about 200 bp upstream and 100 bp downstream of the pre-miRNA, did not vary after RYGB surgery. With remission of T2DM in both groups, RYGB could modulate the expression level of many peripheral blood miRNAs associated with lipid metabolism, insulin secretion, beta-cell function, and insulin resistance. The expression level of peripheral blood diabetes-related miRNA varied in patients with T2DM after receiving RYGB surgery, laying a strong foundation for future studies on this subject. The molecular mechanisms underlying RYGB surgery that can cause aberrant expression of miRNA remains to be determined.