CD8ααT cells exert a pro-inflammatory role in patients with psoriasis.

Background: Psoriasis is a common chronic inflammatory disease caused by excessive activation of CD4T cells, including Th17, Th1 and Th22. The role of CD8T cells in psoriasis pathogenesis remains poorly understood.

Aim: To identify the phenotype of CD8T cells in patients with psoriasis and to investigate its role in the formation of lesions.

Methods: The phenotype of CD8T cells in psoriatic lesions was detected by immunofluorescence staining. Flow cytometry was performed to detect their phenotype in peripheral blood. Thereafter, coculture of CD8ααT cells with autogenous CD4T cells was performed to investigate the function of CD8ααT cells in patients with psoriasis. Finally, pro-inflammatory factors produced by CD8ααT cells were examined by immunofluorescence staining and flow cytometry.

Results: Compared to the CD8αβT cells, CD8ααT cell infiltration in psoriatic lesions markedly increased. Moreover, epidermal CD8ααT cells exhibited tissue-resident memory T cells (T) phenotypes and dermal CD8ααT cells exhibited effector memory (T) phenotypes in psoriatic lesions. Additionally, we found that CD8ααT cells from patients with psoriasis did not express the markers of regulatory T cells and could promote the proliferation of CD4T effector cells and produce interleukin-17 and interferon-γ.

Conclusions: Our findings demonstrate that CD8ααT cells contribute to the pathogenesis of psoriasis by producing pro-inflammatory factors.