Abstract Body: 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.