Gastric bypass surgery in a rat model alters the community structure and functional composition of the intestinal microbiota independently of weight loss.
Obesity is a serious health problem worldwide leading to estimated costs of about $ 150 billion in the Unites States alone1. To treat morbid obesity (defined by BMI > 40), but also to alleviate associated diseases such as type-2 diabetes, Roux-en-Y gastric bypass (RYGB) surgery can be applied.
The study by Haage et al. at hand deals with a RYGB rat model used to study the effect of this surgery on the gut microbiota and its metabolism. The advantage of performing the experiment in an animal model is that it is possible to have matched controls caloric restriction (since the weight loss alone has an impact on the microbial communities residing in the gut).
Bringing methodologies such as 16S rRNA sequencing (to study microbial diversity), metaproteomics, and metabolomics together, drew a very comprehensive picture of the mechanisms associated with severe weight loss. In the study, changes in microbial community were observed in different sections of the gut as well as metabolomic alterations in the plasma (most notably a decrease in several sphingomyelins in the RYGB group, which did not appear in the weight matched control group).
The authors discussed the functional readout of the observed metabolomic changes. Several examples were given where alterations in the relative abundance of microorganisms were associated with metabolic changes. One such example is the higher abundance of Proteobacteria linked to elevated amounts of histamine (a conversion product of the amino acid histidine) in the colon. Bile acids are also extensively discussed for their high relevance to gastro-intestinal research and gut microbiota.
Sven-Bastiaan Haange, Nico Jehmlich, Ute Krügel, Constantin Hintschich, Dorothee Wehrmann, Mohammed Hankir, Florian Seyfried, Jean Froment, Thomas Hübschmann, Susann Müller, Dirk K. Wissenbach, Kang Kang, Christian Buettner, Gianni Panagiotou, Matthias Noll, Ulrike Rolle-Kampczyk, Wiebke Fenske & Martin von Bergen: Gastric bypass surgery in a rat model alters the community structure and functional composition of the intestinal microbiota independently of weight loss. Microbiome 2020