DSS‐induced colitis resulted in the disruption of the gut mucosal barrier, as evidenced by Alcian blue and Periodic acid Schiff (AB‐PAS) stain, as well as the loss of mucin‐secreting goblet cells and downregulation of tight junction proteins (Occludin and ZO‐1); whereas supplement with L. intestinalis protected gut mucosal barrier against DSS‐induced damage (Figure S1D, Supporting Information). Here, MUC5AC is linked to colitis.