MiR-21 Participates in the PD-1/PD-L1 Pathway-Mediated Imbalance of Th17/Treg Cells in Patients After Gastric Cancer Resection.

Abstract

The programmed cell death-1/programmed cell death-ligand 1 (PD-1/PD-L1) pathway has been shown to be involved in trauma-induced immunosuppression and to influence CD4⁺ T cell differentiation. MicroRNA (miR)-21 is a critical player in immune responses. However, it remains largely unknown whether miR-21 is regulated by PD-1 and influences CD4⁺ T-cell lineage choice after gastric cancer resection. In the present study, we analyzed the percentages of T-helper (Th)-17/regulatory T (Treg) cells and PD-1/PD-L1 expression on peripheral blood mononuclear cells (PBMCs) during the perioperative period. We also detected the secretion of interleukin (IL)-17 and transforming growth factor (TGF)-β1 using enzyme-linked immunosorbent assays (ELISAs). Furthermore, PBMCs isolated from patients were transfected with or without adenovirus-short hairpin-PD-1 (Ad-sh-PD1), pre-miR-21 or adenovirus-green fluorescent protein (Ad-GFP), and the percentages of Th17/Treg cells and related transcription factors were measured. In patients who underwent gastric cancer resection, the number of Th17 cells decreased, whereas the number of Treg cells increased, accompanied by an increased expression of PD-1/PD-L1. In addition, the expression of RORγt and IL-17 decreased, whereas the expression of Foxp3 and TGF-β1 increased. In vitro, silencing PD-1 via Ad-sh-PD1 promoted the expression of miR-21 and increased the percentage of Th17 cells, but decreased the percentage of Treg cells. The overexpression of miR-21 increased the percentage of Th17 cells but decreased the percentage of Treg cells. Our study demonstrated that gastric cancer resection altered the balance of Th17/Treg cells and increased PD-1/PD-L1 expression. In the in vitro experiments, the transfection of Ad-sh-PD1 ameliorated Th17/Treg cell imbalance partially by increasing the expression of miR-21.