Roseburia intestinalis is a Firmicute that typically increases after bariatric surgery. It’s also found to be deficient in people who have diabetes. Dr. Seeley coauthored an article showing that Roseburia and other beneficial firmicutes increased significantly in mice that underwent vertical sleeve gastrectomy (Nature 2014;509:183-8). These mice lost weight after surgery, as would be expected, but then showed a preference for the high-protein and carbohydrate-rich foods that Firmicutes need. Their microbiome also showed decreases in the concentration of fat-loving Bacteroides species.
But interestingly, weight loss and microbiome improvement happened only in mice that had a normal bile acid–signaling system. Immediately after surgery, mice engineered to lack bile acid receptors did eat less and lose weight. But a week later, their appetites came back full force, and they actually seemed driven to eat fat. They quickly returned to their presurgical weight. Their microbiome didn’t show the same improvement as their cousins with normal signaling pathways, suggesting that a complex interaction between bacteria and the gut’s physical alteration may be driving weight loss.
“Is weight-loss surgery, then, fixing this ‘broken’ component of the microbiome?” Dr. Seeley asked. “Is Roseburia the causal agent of improvement? Or is it a marker of improvement in an entire community? I would say it’s probably the entire community changing, and changing its interaction with its host organism.”
Dr. Seeley disclosed that he has received financial support from Johnson & Johnson, Novo Nordisk, and Eisai.
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