The mediation of the AHR/IL-22/STAT3/IL-6 axis by soft-shelled turtle () peptide and Chinese pond turtle () peptide contributed to their amelioration effects on intestinal mucosal immunity in immunosuppressed mice.

This study investigated the immunomodulatory effects of soft-shelled turtle () peptide (TP) and Chinese pond turtle () peptide (TMP) on the intestinal mucosal immune system (IMIS). The results demonstrated that TP and TMP improved holistic immunity by restoring the vital immune organ atrophy and proliferation capacity of spleen immune cells. Moreover, TP and TMP significantly increased the serum content of IgA and cytokines that are responsible for immune cell activation and antigen clearance. TP and TMP promoted intestinal B cell activation, class switching recombination, and antibody secreting processes in a T cell-independent manner to increase the SIgA content. Furthermore, TP and TMP enhanced the intestinal barrier by increasing the protein expression of tight junctions (TJs) and adhesion junctions (AJs) and ameliorating the intestinal morphology. Mechanistically, TP and TMP activated the AHR/IL-22/STAT3/IL-6 axis to enhance the IgA response and improve the intestinal barrier, indicating their potential in intestinal health modulation.