Since this study primarily focuses on analyzing the impact of gut microbiota changes on colitis, we observed that the PD-L1 knockout mice showed marked depletion of mucin-protective species (Akkermansia muciniphila) and SCFA-producers (L. murinus), while harboring increased mucolytic bacteria (Bacteroides thetaiotaomicron). The gene discussed is MUC5AC; the disease is colitis.