Background: Programmed death-ligand 1 (PD-L1) is a negative costimulatory molecule, and its main function is widely considered to be in the regulation of T cells. Tumor-associated macrophages (TAMs) are an important part of the tumor microenvironment, and they also play an important role in immunosuppression. However, the relationship between the expression of PD-L1 and TAMs in cervical carcinoma (CC) remains unclear. We detected the expression of PD-L1 and TAMs in tumor tissue to study the correlation between them.
Methods: Immunohistochemical staining of PD-L1, CD68 (pan-macrophage), and CD163 (M2-like macrophage) was performed in 120 cases of cervical squamous cell carcinoma. Logistic regression analysis was used to evaluate the predictors related to positive PD-L1 expression. We also apply the Kaplan–Meier method to study the recurrence-free and overall survival rate of CC patients.
Results: The increase in PD-L1 expression in tumor cells (TC) was significantly correlated with the increase in CD163 density (r =0.8550, p < 0.0001), while PD-L1 in the stroma was also significantly associated with the intratumoral density of CD68- or CD163-positive cells (CD68 p < 0.0001; CD163 p =0.0009). The mean infiltration rates of CD68- and CD163-positive cells in PD-L1-positive TC were significantly higher than in PD-L1-negative TC (CD68 p=0.0095; CD163 p < 0.0001). In multivariate logistic regression analyses, only the density of CD163-positive cells was correlated with the expression of PD-L1 in TC cells (OR 1.52; p =0.032). In prognostic analysis, PD-L1 more than 10% was significantly correlated with short RFS (HR=2.66; p =0.028). For CD163⁺ macrophage evaluation, the density above the median was also significantly correlated with RFS (HR=2.48; p =0.021).
Conclusion: CD163⁺ M2-like macrophage infiltration is highly associated with PD-L1 expression in CC, suggesting that macrophage infiltration can serve as a potential therapeutic target.
Keywords: cervical cancer, programmed death-ligand 1, macrophages, tumor microenvironment