IL-32γ suppressed atopic dermatitis through inhibition of miR-205 expression via inactivation of nuclear factor-kappa B.

ABSTRACT

BACKGROUND: IL-32 is a novel cytokine involved in many inflammatory diseases. However, the role of IL-32γ, an isotype of IL-32, in atopic dermatitis (AD) has not been reported. OBJECTIVE: We investigated the effects of IL-32γ on development of AD and its action mechanisms. METHODS: We used phthalic anhydride (PA) and an MC903-induced AD model using wild-type and IL-32γ transgenic mice. We conducted the therapy experiments by using recombinant IL-32γ protein in a reconstructed human skin model and PA-induced model. We conducted a receiver operating characteristic analysis of IL-32γ with new AD biomarkers, IL-31 and IL-33, in serum from patients with AD. RESULTS: Dermatitis severity and epidermal thickness were significantly reduced in PA- and MC903-induced IL-32γ transgenic mice compared with in wild-type mice. The concentration of AD-related cytokines was reduced in PA- and MC903-induced IL-32γ transgenic mice compared with in wild-type mice. Subsequent analysis showed that IL-32γ inhibits miR-205 expression in PA- and MC903-induced skin tissue samples and TNF-α/IFN-γ-treated HaCaT cells. IL-32γ reduced NF-κB activity in skin tissue samples from PA- and MC903-induced mice and TNF-α/IFN-γ-treated HaCaT cells. NF-κB inhibitor treatment with IL-32γ expression further suppressed expression of inflammatory mediators as well as miR-205 in TNF-α/IFN-γ-treated HaCaT cells. Furthermore, recombinant IL-32γ protein alleviated AD-like inflammation in in vivo and reconstructed human skin models. Spearman correlation analysis showed that serum levels of IL-32γ and miR-205 were significantly concordant in patients with AD. CONCLUSION: Our results indicate that IL-32γ reduces AD through the inhibition of miR-205 expression via inactivation of NF-κB.