Gastrointestinal Hormones, Intestinal Microbiota and Metabolic Homeostasis in Obese Patients: Effect of Bariatric Surgery.

Background/Aim: Bariatric surgery has proven efficacy in the modulation of a number of gut peptides that can contribute to improvement of diabetes and its associated metabolic changes. In order to evaluate dietary intake, nutritional assessment and plasma levels of gastrointestinal peptides, we enrolled severely obese patients before and after bariatric surgery. Patients and Methods: We evaluated food intake, plasma levels of peptide YY (PYY), glucagon-like peptide-1/2 (GLP-1/2), ghrelin (GHR), orexin (ORE) and cholecystokinin (CCK), body composition and fecal microbiota in 28 severely obese patients and 28 healthy normal-weight controls. All parameters were evaluated at 0 time and 6 months after bariatric surgery. Results: In obese patients we found a higher intake of nutrients, a decrease of free fat mass and an increase of BMI (body mass index), a significant decrease of GLP-1 and an increase of GLP-2, GHR and PYY with respect to controls, further increase in GLP-2, GHR and PYY, as well as increase over control values of GLP-1 after bariatric surgery. Obese individuals were found to harbor a community dominated by members of the Clostridial clusters XIVa and IV, whereas prominent bands after surgery were identified as Lactobacillus crispatus and Megasphaera elsdenii-related phylotype. Conclusion: The beneficial effects of bariatric surgery may at least in part be accounted for changes in circulating gastrointestinal (GI) peptides and fecal microbiota.