Abstract P3121: Temporal Changes in Blood and Fecal Metabolites and Fecal Microbiome After Bariatric Surgery

Background: Temporal changes in blood and fecal metabolites and fecal microbiome following bariatric surgery remain unclear. This study thus aimed to explore those intra-individual changes after bariatric surgery. Methods: Plasma and stool samples were collected from 62 patients who underwent first-time Roux-en-Y gastric bypass or sleeve gastrectomy at pre- and 3- and 12-month post-surgery. Global metabolite profiling and targeted short-chain fatty acid profiling were performed using LC-MS/MS. The microbiome was profiled by shotgun metagenomic sequencing. Paired Wilcoxon signed-rank tests and fold change (FC) were applied. Significant changes (FDR<0.05 and FC>1.5 or <0.67) were categorized into three patterns: early changed, late sustained (i.e., significant when comparing 3-month post- to pre-surgery, which sustained comparing 12- to 3-month post-surgery); early changed, late reversed (significant opposite changes in both periods); early unchanged, late changed (only significant when comparing 12- to 3-month post-surgery). Results: Significant changes were observed in 274 plasma metabolites,143 fecal metabolites, and 102 microbial species. Major plasma metabolite changes involved sustained increases in primary bile acids and hemoglobin-related metabolites, and a decrease in tryptophan; reverses in ketone bodies, secondary bile acids, and fatty acids; late increases in lysophospholipids, benzoate, and energy-related metabolites, and a late decrease in long-chain fatty acids. Major fecal metabolite changes included sustained increases in medium- and long-chain fatty acids, and decreases in secondary bile acids and dipeptides; late increases in energy-related metabolites, and decreases in primary bile acids and sterols. Major microbial species changes were sustained increases in Streptococcus parasanguinis , S. salivarius , S. thermophilus , E. coli , and Klebsiella pneumoniae, and decreases in Agathobacter rectalis , Anaerobutyricum hallii , Dorea_A longicatena, Fusicatenibacter saccharivorans, and Roseburia inulinivorans ; reversed changes in Copromonas sp900066785 and Ruminococcus_D bicirculans ; and late increases in Agathobaculum butyriciproducens and Dysosmobacter butyriciproducens . Most changes did not differ significantly by surgical type or patient gender. Conclusions: Our findings indicate temporal changes in metabolites and microbiome following bariatric surgery, warranting further research on these changes and their link to long-term health outcomes.