"Omics" Prospective Monitoring of Bariatric Surgery: Roux-En-Y Gastric Bypass Outcomes Using Mixed-Meal Tolerance Test and Time-Resolved (1)H NMR-Based Metabolomics.

Roux-en-Y gastric bypass (RYGB) surgery goes beyond weight loss to induce early beneficial hormonal changes that favor glycemic control. In this prospective study, ten obese subjects diagnosed with type 2 diabetes underwent bariatric surgery. Mixed-meal tolerance test was performed before and 12 months after RYGB, and the outcomes were investigated by a time-resolved hydrogen nuclear magnetic resonance ((1)H NMR)-based metabolomics. To the best of our knowledge, no previous omics-driven study has used time-resolved (1)H NMR-based metabolomics to investigate bariatric surgery outcomes. Our results presented here show a significant decrease in glucose levels after bariatric surgery (from 159.80 ± 61.43 to 100.00 ± 22.94 mg/dL), demonstrating type 2 diabetes remission (p < 0.05). The metabolic profile indicated lower levels of lactate, alanine, and branched chain amino acids for the operated subject at fasting state after the surgery. However, soon after food ingestion, the levels of these metabolites increased faster in operated than in nonoperated subjects. The lipoprotein profile achieved before and after RYGB at fasting was also significantly different, but converging 180 min after food ingestion. For example, the very low-density lipoprotein, low-density lipoprotein, N-acetyl-glycoproteins, and unsaturated lipid levels decreased after RYGB, while phosphatidylcholine and high-density lipoprotein increased. This study provides important insights on RYGB surgery and attendant type 2 diabetes outcomes using an "omics" systems science approach. Further research on metabolomic correlates of RYGB surgery in larger study samples is called for.

Blood Metabolome Changes Before and After Bariatric Surgery: A (1)H NMR-Based Clinical Investigation.

Excessive body fat and obesity have adverse health effects and result in significant morbidity such as type 2 diabetes mellitus. The health burden of obesity can be reduced with the Roux-en-Y gastric bypass (RYGB) weight-loss bariatric surgery. Little is known on the molecular changes that occur at the metabolome level before and after bariatric surgery, with a view to clinical biomarker development. Hence, we employed a metabolomics approach in 10 obese diabetic patients who underwent bariatric surgery. Metabolomics data were obtained by T2- and diffusion-edited hydrogen nuclear magnetic resonance ((1)H NMR) spectra to monitor the metabolic and lipoprotein profiles, and gas chromatography-mass spectrometry (CG-MS) to access the fatty acid profile before and 12 months after RYGB. Using hierarchical partial least squares discriminant analysis, we found that RYGB induces several key metabolic alterations associated with glucose homeostasis, as well as fatty acid and amino acid metabolism. The levels of lactate (Krebs' intermediate cycle) decreased after RYGB. The leucine, isoleucine, valine, lactate, and glucose levels were higher in the samples before RYGB (p<0.05). Additionally, the levels of very low-density lipoprotein, unsaturated lipids, and N-acetyl-glycoprotein were higher before RYGB. By contrast, levels of the high-density lipoprotein and phosphatidylcholine were higher after bariatric surgery. These results collectively offer important holistic integrative biology data to develop future clinically relevant metabolomics biomarkers related to bariatric surgery in connection with obesity.