The Role of the Gut Microbiota in Sustained Weight Loss Following Roux-en-Y Gastric Bypass Surgery
The aim of the study was to investigate the role of the gut microbiota in weight regain or suboptimal weight loss following Roux-en-Y gastric bypass (RYGB).
Materials and Methods
The gut microbiota composition in post-RYGB patients who experienced successful weight loss (SWL, n = 6), post-RYGB patients who experienced poor weight loss (PWL, n = 6), and non-surgical controls (NSC, n = 6) who were age- and BMI-matched to the SWL group (NSC, n = 6) were characterized through 16S rRNA gene sequencing. To further investigate the impact of the gut microbiota on weight profile, human fecal samples were transplanted into antibiotic-treated mice.
Orders of Micrococcales and Lactobacillales were enriched in SWL and PWL groups compared to the NSC group. No significant difference was observed in the gut microbiota composition between PWL and SWL patients. However, transfer of the gut microbiota from human patients into antibiotic-treated mice resulted in significantly greater weight gain in PWL recipient mice compared to SWL recipient mice. A few genera that were effectively transferred from humans to mice were associated with weight gain in mice. Among them, Barnesiella was significantly higher in PWL recipient mice compared to SWL and NSC recipient mice.
These results indicate that the gut microbiota are at least functionally, if not compositionally, different between PWL and SWL patients. Some taxa may contribute to weight gain after surgery. Future studies will need to determine the molecular mechanisms behind the effects of the gut bacteria on weight regain after RYGB.
KeywordsGastric bypass surgery Weight regain Gut microbiota Poor weight loss RYGB surgery
We would like to acknowledge Ross Crosby, Ph.D., Carrie Nelson, RN, and Jacob Shreffler for their input and help with study design, coordination, and execution.
This study is funded by the Neuropsychiatric Research Institute (Fargo, North Dakota) and from the Core Synthesis and Analytical Services Facility which was made possible by NIH Grant Number P30GM103332 from the National Institute of General Medicine (NIGMS).
Compliance with Ethical Standards
Conflict of Interest
Ian M. Carroll reports personal fees from Vivelix and Salix pharmaceuticals for being consultant outside the submitted work. Kristine J. Steffen reports grants from the Center for Protease Research - NIH COBRE Pilot Grant through NDSU during the conduct of the study; grants from NIH, grants from Sanford Profile/NDSU, grants from Shire Pharmaceuticals, outside the submitted work. Amanda E. Brooks reports grants from NIH IDEA Center, during the conduct of the study. Anthony A. Fodor reports grants from NIH during the conduct of the study; personal fees from Second Genome, Salix Corporation, and the NKarta corporation outside the submitted work. Farnaz Fouladi, Emily C. Bulik-Sullivan, Matthew C. B. Tsilimigras, and Michael Sioda have no conflict of interest.
Ethical Approval Statement
All procedures performed in studies involving human participants were in accordance with the ethical standards of the University of North Dakota and North Dakota State University (NDSU) Institutional Review Boards. The study was registered at www.clinicaltrials.gov (NCT02654496). All Institutional Animal Care and Use Committee of North Dakota State University guidelines for the care and use of animals were followed.
Informed Consent Statement
Informed consent was obtained from all individual participants included in the study.
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