| Objective To investigate the mechanism by which icariin inhibits immune escape in nasopharyngeal carcinoma by modulating the regulatory T cell/helper T cell(Treg/Th) balance and the programmed cell death protein 1/programmed death-ligand 1(PD-1/PD-L1)pathway.Methods A rat NPC model was established by subcutaneous injection of dinitrosopiperazine into the axilla.A total of 30 successfully modeled rats were selected and randomly divided into the model group(n=10),the low-dose icariin group(20 mg/kg,n=10),and the high-dose icariin group(50 mg/kg,n=10).A normal control group(n=10) was also established separately.HE staining was employed to observe the pathological morphology of nasopharyngeal tissue in each group.Western blot was used to detect the expression of vascular endothelial growth factor(VEGF),matrix metalloproteinase-9(MMP-9),and PD-1/PD-L1 on monocytes in the nasopharyngeal tissue of each group.ELISA and flow cytometry were employed to analyze the levels of interleukin-10(IL-10) and transforming growth factor-β(TGF-β) in peripheral blood,the percentages of CD4+T and CD8+T cells,and the proportion of Treg(CD4+CD25+T) cells after the last administration.Results Compared with the control group,the model group exhibited squamous epithelial hyperplasia,nuclear atypia,and inflammatory infiltration.The tumor microenvironment showed upregulation of pro-carcinogenic factors(VEGF,MMP-9) and immunosuppressive indicators(Treg cells,IL-10,TGF-β,PD-1/PD-L1)(P<0.05),while the proportion of effector T cells(CD4+T,CD8+T) decreased(P<0.05).Icariin intervention dose-dependently reversed these pathological features and immune imbalances in both the high-and low-dose groups(P<0.05).Notably,the high-dose group significantly suppressed PD-1/PD-L1 expression and restored the proportion of effector T cells(P<0.05).Conclusion Icariin may block the immune escape process in nasopharyngeal carcinoma by synergistically inhibiting Treg cell expansion and the PD-1/PD-L1 signaling axis,thereby reshaping Th immune homeostasis and reversing the tumor immunosuppressive microenvironment. |