CD8αα(+)T cells exert a pro‐inflammatory role in patients with psoriasis

BACKGROUND: Psoriasis is a common chronic inflammatory disease caused by excessive activation of CD4(+)T cells, including Th17, Th1 and Th22. The role of CD8(+)T cells in psoriasis pathogenesis remains poorly understood. AIM: To identify the phenotype of CD8(+)T cells in patients with psoriasis and to investigate its role in the formation of lesions. METHODS: The phenotype of CD8(+)T cells in psoriatic lesions was detected by immunofluorescence staining. Flow cytometry was performed to detect their phenotype in peripheral blood. Thereafter, coculture of CD8αα(+)T cells with autogenous CD4(+)T cells was performed to investigate the function of CD8αα(+)T cells in patients with psoriasis. Finally, pro‐inflammatory factors produced by CD8αα(+)T cells were examined by immunofluorescence staining and flow cytometry. RESULTS: Compared to the CD8αβ(+)T cells, CD8αα(+)T cell infiltration in psoriatic lesions markedly increased. Moreover, epidermal CD8αα(+)T cells exhibited tissue‐resident memory T cells (T(RM)) phenotypes and dermal CD8αα(+)T cells exhibited effector memory (T(EM)) phenotypes in psoriatic lesions. Additionally, we found that CD8αα(+)T cells from patients with psoriasis did not express the markers of regulatory T cells and could promote the proliferation of CD4(+)T effector cells and produce interleukin‐17 and interferon‐γ. CONCLUSIONS: Our findings demonstrate that CD8αα(+)T cells contribute to the pathogenesis of psoriasis by producing pro‐inflammatory factors.