RA is a ligand binding to RARs, which activate or repress transcription of numerous genes important for physiological events.[42] In addition to suppressing inflammation in autoimmunity.[43, 44] RA exhibits more comprehensive benefits, such as enhancing defense responses.[45] Our findings suggested that in colitis, RA mediated the protective effect of L. intestinalis by altering the C/EBPA‐SAA1/2‐Th17 axis. This evidence concerns the gene SAA1 and colitis.