The concept of stomach surgery to help patients lose weight is well understood – a smaller stomach will feel fuller, after less food. However, University of Auckland research shows there is more to the surgery than simple physics.
Lead investigator Dr Rinki Murphy says post-surgery changes in the gut microbial community appear to be linked to type 2 diabetes remission. If researchers can understand these gut microbial changes, they may be able to isolate and synthesise the positive gut bacteria and use them as a treatment for type 2 diabetes. For example, as next-generation probiotics, faecal transplants via colonoscopy, or other medications.
Dr Murphy studied 14 patients – all obese and all with type 2 diabetes – and monitored the gut microbiota (mainly bacteria) in their fecal samples immediately before surgery and 12 months later.
Half of the patients underwent gastric bypass surgery, whereby the stomach and first part of the small bowel is disconnected (bypassed) from the passage of food. The other half underwent a sleeve gastrectomy, where a large portion of the stomach is removed. Gastric bypass is the most common, although more expensive and complex, surgical option.
“In both groups selected for the gut microbiota analysis, five out of the seven patients’ type 2 diabetes was in remission one year after surgery, with similar weight loss and eating habits. We wanted to test whether diabetes remission was associated with a particular shift in gut microbiota.”
Dr Murphy discovered that both surgeries resulted in substantial changes to the gut microbial community, with more dramatic changes after gastric bypass.
“The predicted function of the gut microbiota after gastric bypass was more favourable for maintaining weight loss and diabetes remission, than after sleeve gastrectomy.”
Dr Murphy used NZGL’s bioinformatics service to analyse whole genome sequencing data, to help pinpoint the types of bacteria found in the gut and begin to understand which may be associated with type 2 diabetes remission.
“The next step is to analyse the gut microbiota from a larger sample of patients who took part in the study – comparing gastric bypass and sleeve gastrectomy – to see whether these changes are confirmed and to see if we can predict those who will respond best to each type of bariatric surgery by their baseline gut microbiota.”
NZGL Services:20 hours bioinformatics
Peter Tsai, Bioinformatician, The University of Auckland Bioinformatics Institute
“The bioinformatics analysis included quality assessment of data, following extensive taxonomy classification of millions of sequences against known human gut bacteria. The process helped us to identify the key difference pre and post different types of surgical procedures. The project is unique and aimed to provide direct benefits towards patients with type 2 diabetes.”