Bifidobacterium alleviates spontaneous and chemical-induced colitis by regulating cytokines or inducing specific immunomodulatory mechanisms (for example, Bifidobacterium infantis can accelerate the expression of Foxp3 in the intestine by activating the PD-1/PD-L1 signaling pathway. It can also promote the expression of IL-10 and TGF-β1 to reduce intestinal inflammation and has a therapeutic effect in IBD mouse models). The gene discussed is FOXP3; the disease is colitis.