The concept and study are novel and deserve to do further mechanistic investigations, such as the following: (1) how vitamin D and butyrate influence each other in upregulating AhR; (2) how molecules/cytokines (such as VD3, BU, AhR, IL-22, and IL-17a) can ameliorate Salmonella-induced colitis by modulating mucosal immunocytes (T cells, B cells, and monocytes/macrophages); (3) the role of AhR-mediated autophagy on cross talk between IECs and macrophage to promote intestinal barrier function. The gene discussed is IL17A; the disease is colitis.