Reduced EZH2 Expression in Circulating CD8-Positive T Cells and Monocytes in Psoriasis

Enhancer of Zeste Homologue 2 (EZH2) is an epigenetic regulator involved in immune cell differentiation and function; however, its role in psoriasis remains unknown. This study aimed to evaluate EZH2 expression in peripheral blood mononuclear cells from patients with psoriasis and explore its potential functional relevance to disease pathogenesis. Peripheral blood samples were obtained from 40 psoriasis patients and 18 healthy controls, and EZH2 expression in T cell and monocyte subsets was analysed by flow cytometry. EZH2 expression was significantly reduced in circulating CD8+ naïve and memory T cells, as well as in monocyte subsets from psoriasis patients compared to healthy controls. EZH2 levels in CD8+ naïve T cells showed a significant inverse correlation with disease severity scores. Functional analyses revealed that pharmacological EZH2 inhibition suppressed IL-17A expression in peripheral blood mononuclear cells under IL-23/IL-1β stimulation. In addition, immunofluorescence staining identified EZH2-positive T cells and monocytes within psoriatic skin lesions. Collectively, these findings suggest that EZH2 may be involved in the regulation of type 3 inflammatory responses and may therefore represent an epigenetic regulator contributing to psoriasis pathogenesis.