Aim: The programmed death 1/programmed death 1 ligand (PD-1/PD-L1) pathway can decrease the immune clearance effects of antigen-presenting cells and T lymphocytes to promote immune evasion of cervical cancer cells. However, the effects of this pathway on cervical intraepithelial neoplasia (CIN) progression and squamous cell carcinoma (SCC) metastasis are not clear. We herein investigated whether human papillomavirus infection could affect PD-1 and PD-L1 expression in CIN, and whether their expression is associated with CIN progression and SCC metastasis.
Methods: We collected paraffin-embedded samples from two cohorts of patients: (i) CIN samples from cohort I (40 women who tested positive or negative for high-risk human papillomavirus [HR-HPV] with grades 0, I, and II-III CIN); and (ii) paired primary and metastatic tumor samples from cohort II (20 SCC patients with or without metastasis). Immunohistochemistry was used to detect expressions of PD-L1 in tumor cells and PD-1 in tumor-associated macrophages and tumor-infiltrating lymphocytes. We also measured P16INK4a expression and interferon-γ levels in the cervical tissues.
Results: The most common HPV type seen in both cohorts of patients was HPV16, followed by HPV18. Increase in PD-L1 and PD-1 expression was positively correlated with HPV-positivity, increase in CIN grade, and tumor metastasis. Furthermore, upregulation of the PD-1/PD-L1 pathway was associated with decreased expression of the pro-inflammatory cytokine, interferon-γ and increased expression of P16INK4a .
Conclusion: Expression of PD-L1 and PD-1 could be used as clinical prognostic biomarkers for evaluating CIN and cervical cancer because of its positive correlation with CIN progression and tumor metastasis.
Keywords: cervical carcinoma; cervical intraepithelial neoplasia; human papillomavirus; programmed death 1; programmed death 1 ligand.
© 2017 Japan Society of Obstetrics and Gynecology.