Bariatric Surgery Gut Microbiome

Metabolic and bariatric surgery (MBS) improves metabolic health through multiple mechanisms. Apart from altered bile acid and gut hormone signaling, significant changes in the gut microbiome composition contribute to the beneficial metabolic effects of MBS. The latter can reverse elevated circulating lipopolysaccharide (LPS) levels, termed metabolic endotoxemia, typical for obesity and metabolic association steatotic liver disease (MASLD). Nevertheless, MBS can also negatively affect intestinal wall integrity, thereby promoting bacterial translocation and LPS delivery to the liver. Indeed, post-MBS liver failure was hypothesized to result from increased bacterial translocation resulting in sepsis, from toxic bile acid signaling, or from severe malnutrition. However, mechanistic evidence to substantiate these hypotheses is lacking. There is equally a paucity of data on how biliary limb length variation modulates the gut-liver axis. This lack of insights prevents standardization of MBS limb lengths to balance the risk of liver failure and maximization of weight loss.