LAUSR

Mucosal Immunology Commensal intestinal bacteria respond to dietary changes by modifying gene expression, leading to shifts in the amounts of bacterial antigens encountered by the intestinal immune system. Wegorzewska et al. developed a mouse model system to investigate whether CD4+ T cell recognition of antigens of the gut symbiont Bacteroides thetaiotaomicron is subject to dietary modulation. T cell receptor–transgenic T cells that recognized a bacterial outer-membrane vesicle protein differentiated into both regulatory and effector T cells, and colitis emerged after selective depletion of the regulatory T cells. Dietary glucose strongly repressed the T cell–detected antigen. Thus, dietary modifications that reduce bacterial expression of immunodominant antigens targeted by T cells could ameliorate some forms of human inflammatory bowel disease. Sci. Immunol. 4 , eaau9079 (2019).