Apremilast downregulates interleukin-17 production and induces splenic regulatory B cells and regulatory T cells in imiquimod-induced psoriasiform dermatitis

•Apremilast alleviated imiquimod-induced psoriasiform dermatitis.•Apremilast inhibited infiltration of IL-17A-positive cells into the skin.•Apremilast increased infiltration of Foxp3-postive cells.•Apremilast reduced mRNA expression of IL-17A, IL-17 F, and IL-22 in the skin.•Apremilast induced regulatory T cells and regulatory B cells in the spleen.