Macrophages participate in the immunosuppression of condyloma acuminatum through the PD-1/PD-L1 signaling pathway

Abstract

BACKGROUND: The aim of this study was to investigate whether macrophages can participate in the immunosuppression of condyloma acuminatum (CA) by expressing PD-1/PD-L1. METHODS: The infiltration of macrophages and expression of programmed death-1 (PD-1) and PD-1 ligand 1 (PD-L1) on wart lesions and in normal skin tissues were detected by immunohistochemistry assay. The amounts of M1- and M2-type macrophages derived from THP-1 cells were measured by flow cytometry. The expression of cytokines on macrophages was examined by using enzyme-linked immunosorbent assay (ELISA). The protein expression of PD-1 and PD-L1 on macrophages was detected by western blotting. RESULTS: The macrophages were significantly increased, while PD-1 and PD-L1 were highly expressed on wart lesions compared to normal controls. More M2-like macrophages than M1-type macrophages were present on wart lesions. The M2-like macrophages in the CA groups showed high expression of interleukin-10 (IL-10), transforming growth factor (TGF-β), PD-1, and PD-L1 compared to normal controls. CONCLUSION: Macrophages participate in the immunosuppression of CA by expressing PD-1/PD-L1.