Gut microbiota more altered after gastric bypass than sleeve gastrectomy

More alterations in gut microbiota are found after gastric bypass surgery compared with sleeve gastrectomy, according to study findings presented at the 51st European Association for the Study of Diabetes Annual Meeting.

“There are striking differences between gut microbiota response to sleeve gastrectomy and gastric bypass surgery despite similar changes in food intake and medication use afterward, with increased functional capacity to produce more short-chain fatty acids after gastric bypass, but not sleeve gastrectomy, which may contribute to the superior metabolic benefits seen,” Rinki Murphy, MBChB, FRACP, PhD, of the department of medicine and Maurice Wilkins Centre for Molecular Biodiscovery at the University of Auckland in New Zealand, told Endocrine Today.

Murphy and colleagues evaluated 14 patients with obesity and type 2 diabetes before and 1 year after sleeve gastrectomy (n = 7) or gastric bypass (n = 7) procedures to determine the differences in gut microbiota after both surgeries.

Rinki Murphy

Researchers used Illumina HiSeq 2000 to obtain whole-metagenome shotgun sequencing of genomic DNA fragments from stool samples. Metabolic outcomes and food diaries also were collected. Patients were considered in partial remission of diabetes if HbA1c was 48 mmol/mol or less, and complete remission was defined as 38 mmol/mol or less. Patients also had to be off glucose-lowering therapies to be considered as having complete or partial remission.

Both surgeries resulted in similar weight reductions and estimated caloric intake and dietary components.

There was greater remission of diabetes after gastric bypass (four complete remission; one partial remission) compared with sleeve gastrectomy (one complete remission; four partial remission).

Compared with sleeve gastrectomy, in which there were no major changes in phyla and increase in only the Bacteroides species, gastric bypass revealed greater changes in taxonomy of gut microbiota with three major phyla differences.

Significant increases in the Roseburia species were observed among participants who achieved remission, regardless of surgery type.

Among patients who achieved diabetes remission after gastric bypass, there were more significant changes in Kyoto Encyclopedia of Genes and Genomes (KEGG) gene function compared with patients who underwent sleeve gastrectomy. These results were similar for KEGG pathways. However, no common KEGG gene functions or pathways were significantly altered after either surgery for patients who achieved diabetes remission.

“Gastric bypass and sleeve gastrectomy type of bariatric surgery, despite having similar changes in food intake, medications and body weight reductions, are associated with very different and often opposite gut microbiota changes in people who have type 2 diabetes prior to surgery,” Murphy said. “The changes in gut microbiota and their functional genetic capacity following gastric bypass are linked with more favorable host metabolic outcomes than the changes observed after sleeve gastrectomy due to the increased capacity of such bacteria to produce more short-chain fatty acids and be more motile after the bypass.”

Murphy added that validation of the results with the remaining samples collected is planned.

“Future work with fecal transplant experiments would help clarify whether the gut microbiota communities after either type of surgery are causally effective in achieving metabolic improvements in recipients with type 2 diabetes, and could potentially lead to the development of beneficial probiotics,” she said. – by Amber Cox

Reference:

Murphy R, et al. Abstract #221. Presented at: 51st EASD Annual Meeting; Sept. 14-18, 2015; Stockholm.

Disclosure: The study was funded in part by the Maurice Wilkins Centre.