Immunohistochemical Study of Psoriasis-related Gene Expression in Imiquimod-induced Psoriasis-like Mouse Model / 대한피부과학회지

BACKGROUND: Psoriasis is a chronic inflammatory skin disease with an incidence of 0.5~3% of the worldwide population. The pathogenesis of psoriasis is related to dysregulated keratinocyte function and immune reactions. Notably, genetic factors are considered important etiological contributors. Globally, several researchers have recently performed genome-wide association studies (GWAS) to identify the genes related with psoriasis. OBJECTIVE: We aimed to investigate the expression pattern of 2 candidate genes that were identified by GWAS. These include interleukin 28 receptor alpha (IL28RA) and CUB and Sushi multiple domains 1 (CSMD1). METHODS: We applied imiquimod cream to develop a psoriasis-like mouse model and obtained skin tissue. We performed immunohistochemistry to detect the expression of IL-28A and CSMD1. RESULTS: IL28RA expression increased at an early time point such as 1 day after the topical application of 5% imiquimod cream. However, its expression returned to baseline levels 2 weeks after the topical application of imiquimod cream. CSMD1 expression also increased after the topical application of imiquimod, with increased expression particularly observed in the upper epidermal layer. Notably, CSMD1 expression decreased 7 days after imiquimod cream application. CONCLUSION: These results suggest that IL28RA and CSMD1 may play key roles in the pathogenesis of psoriasis.

IL-23-induced macrophage polarization and its pathological roles in mice with imiquimod-induced psoriasis

Macrophages acquire distinct phenotypes during tissue stress and inflammatory responses. Macrophages are roughly categorized into two different subsets named inflammatory M1 and anti-inflammatory M2 macrophages. We herein identified a unique pathogenic macrophage subpopulation driven by IL-23 with a distinct gene expression profile including defined types of cytokines. The freshly isolated resting mouse peritoneal macrophages were stimulated with different cytokines in vitro, the expression of cytokines and chemokines were detected by microarray, real-time PCR, ELISA and multiple colors flow cytometry. Adoptive transfer of macrophages and imiquimod-induced psoriasis mice were used. In contrast to M1- and M2-polarized macrophages, IL-23-treated macrophages produce large amounts of IL-17A, IL-22 and IFN-γ. Biochemical and molecular studies showed that IL-23 induces IL-17A expression in macrophages through the signal transducer and activator of transcription 3 (STAT3)-retinoid related orphan receptor-γ T (RORγT) pathway. T-bet mediates the IFN-γ production in IL-23-treated macrophages. Importantly, IL-23-treated macrophages significantly promote the dermatitis pathogenesis in a psoriasis-like mouse model. IL-23-treated resting macrophages express a distinctive gene expression prolife compared with M1 and M2 macrophages. The identification of IL-23-induced macrophage polarization may help us to understand the contribution of macrophage subpopulation in Th17-cytokines-related pathogenesis.