Metabolic enzymes participate in reciprocal interactions with metabolites derived from microbiota; HK2, a regulator of glycolysis, is inhibited by butyrate, produced by commensals such as Faecalibacterium, and the deletion of epithelial HK2 confers protection against colitis (67), elucidating a feedback loop where microbial metabolites attenuate host glycolysis to mitigate inflammation. Here, HK2 is linked to colitis.