KCS

Bariatric surgery is one of the most effective treatments for obesity and its complications. However, metabolic changes in bariatric surgery are not clear. In this study, we performed metabolic profiling of serum from 38 morbid obese patients who underwent bariatric surgery using nuclear magnetic resonance spectroscopy (NMR) and liquid chromatography/ mass spectrometry (LC/MS). We integrated metabolic profiling and gut microbiota profiling data to observe changes in human metabolism and intestinal environment after bariatric surgery. Samples were collected before surgery and 6 months after surgery. In global profiling using NMR, metabolites including amino acids, organic acids, carbohydrates, and short chain fatty acids were identified in serum of patients. Principal component analysis (PCA) score plot showed a clear separation between before surgery and after surgery group. We found that serum metabolites associated with obesity metabolism (branched-chain amino acids (BCAAs) and aromatic amino acids) and metabolites related to energy metabolism (glucose, glutamate, lactate, and mannose) were significantly decreased after surgery. Interestingly, BCAAs, glucose, and mannose were positively correlated with total cholesterol, LDL cholesterol, triglyceride, which are clinical indicators related to lipid metabolism. In correlation analysis of metabolome and gut microbiome, BCAA metabolites were positively correlated with Roseburia faecis. Glycine and dimethyl sulfone were related to Streptococcus infantis and Rothia dentocariosa. In addition, we performed a quantitative analysis of serum bile acids (BAs) using LC/ triple quadrupole MS (LC/TQ-MS) to measure the level of circulating bile acids reabsorbed in the intestine. After surgery, the total level of BAs increased compared to before surgery. Particularly, GDCA, TDCA, LCA, GLCA, and TLCA, which are secondary BAs, significantly increased after surgery, while primary BAs had little change. This study demonstrates that NMR/MS-based metabolic profiling analysis and it’s integration with microbiome data provides insight into the metabolic changes after bariatric surgery.