Title. Circadian clock at the interface of mucosal immunity, gut microbiota, and epithelial barrier in inflammatory bowel disease. The authors point out increasing evidence linking circadian disruptions, such as shift work, jet lag, sleep loss, light misalignment, and irregular eating patterns, to the risk of IBD and associated symptoms and inflammatory activity. They elaborate that the intestinal circadian system is coordinated by the central clock and peripheral clocks in epithelial and immune cells. These oscillators stimulate innate and adaptive immune responses; diurnal microbial rhythms and metabolite production; and regulate epithelial tight junctions, mucus production, antimicrobial peptides, and regenerative programs. Microbial metabolites (short-chain fatty acids, bile acids, and tryptophan derivatives) can entrain host clocks, creating a bidirectional immunity-microbiota barrier network. This is a very interesting article that summarizes mechanistic and clinical data on circadian clock gene networks in IBD.