IDO1 and infectious otitis media: Li et al. [267] found that PNS had significant preventive and immunomodulatory effects on AOM/DSS-induced CAC mice, and was able to alleviate the immunosuppression of Treg cells in the colonic tissue microenvironment of CAC mice by inhibiting signal transduction and direct mediation of indoleamine 2,3-dioxygenase 1 (IDO1) expression by transcription 1 (STAT1), reducing macrophage aggregation, and reshaping the CAC immune microenvironment.