Lysates ofMethylococcus capsulatusBath induce a lean-like microbiota, intestinal FoxP3⁺RORγt⁺IL-17⁺Tregs and improve metabolism

AbstractInteractions between host and gut microbial communities may be modulated by diets and play pivotal roles in securing immunological homeostasis and health. Here we show that intake of feed based on whole-cell lysates of the non-commensal bacteriumMethylococcus capsulatusBath (McB) as protein source reversed high fat high sucrose-induced changes in the gut microbiota to a state resembling that of lean, low fat diet-fed mice, both under mild thermal stress (T22°C) and at thermoneutrality (T30°C). McB feeding selectively upregulated triple positive (Foxp3+RORγt+IL-17+) regulatory T cells in the small intestine and colon, and enhanced mucus production and glycosylation status suggesting improved gut health. Mice receiving McB lysates further exhibited improved glucose regulation, reduced body and liver fat along with diminished hepatic immune infiltration. Collectively, these data points towards profound whole-body effects elicited by the McB lysate suggesting that it may serve as a potent modulator of immunometabolic homeostasis.