Ileal microbial shifts after Roux-en-Y gastric bypass orchestrate changes in glucose metabolism through modulation of bile acids and L-cell adaptation

• Published in: Scientific reports Vol. 11; no. 1; p. 23813
• Main Authors: Dang, Jerry T., Mocanu, Valentin, Park, Heekuk, Laffin, Michael, Tran, Caroline, Hotte, Naomi, Karmali, Shahzeer, Birch, Daniel W., Madsen, Karen
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 10.12.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 631/326/41; 692/163/2743/137; 692/163/2743/2037; 692/163/2743/393; 692/4020/198; Acids; Animals; Bile; Bile acids; Bile Acids and Salts - metabolism; Biomarkers; Blood Glucose; Cell Count; Cell density; Cell proliferation; Disease Susceptibility; Escherichia; Gastric bypass; Gastric Bypass - adverse effects; Gastric Bypass - methods; Gastrointestinal Microbiome; Gastrointestinal surgery; Glucagon; Glucagon-Like Peptide 1 - metabolism; Glucose; Glucose - metabolism; Glucose tolerance; Homeostasis; Humanities and Social Sciences; Ileal bypass; Ileum - metabolism; Ileum - microbiology; Intestinal Mucosa - metabolism; Intestinal Mucosa - microbiology; L Cells - metabolism; Lactobacillus; Mice; multidisciplinary; Rats; Science; Science (multidisciplinary); Shigella
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-021-03396-4

Roux-en-Y gastric bypass (RYGB)-induced glycemic improvement is associated with increases in glucagon-like-peptide-1 (GLP-1) secreted from ileal L-cells. We analyzed changes in ileal bile acids and ileal microbial composition in diet-induced-obesity rats after RYGB or sham surgery to elucidate the early and late effects on L-cells and glucose homeostasis. In early cohorts, there were no significant changes in L-cell density, GLP-1 or glucose tolerance. In late cohorts, RYGB demonstrated less weight regain, improved glucose tolerance, increased L-cell density, and increased villi height. No difference in the expression of GLP-1 genes was observed. There were lower concentrations of ileal bile acids in the late RYGB cohort. Microbial analysis demonstrated decreased alpha diversity in early RYGB cohorts which normalized in the late group. The early RYGB cohorts had higher abundances of Escherichia–Shigella but lower abundances of Lactobacillus , Adlercreutzia , and Proteus while the late cohorts demonstrated higher abundances of Escherichia–Shigella and lower abundances of Lactobacillus . Shifts in Lactobacillus and Escherichia–Shigella correlated with decreases in multiple conjugated bile acids. In conclusion, RYGB caused a late and substantial increase in L-cell quantity with associated changes in bile acids which correlated to shifts in Escherichia–Shigella and Lactobacillus . This proliferation of L-cells contributed to improved glucose homeostasis.