Effects of HPV16 E6/E7 oncoproteins on the response of epithelial cells to toll-like receptors (TLRS) ligands

OLIVERA, CAROLINA; MOSSMAN, JESSICA; FERREYRA, FERNANDO NICOLAS; PAIRA, DANIELA A.; MARTINEZ, MARIA SOL; MOTRICH, RUBEN D.; CUFFINI, CECILIA G.; RIVERO, VIRGINIA E.

Barcelona

Congreso; 34th International Papillomavirus Conference & Basic Science, Clinical and Public Health Workshops. International Papillomavirus Society. USA.; 2021

Introduction Persistent infections by human papillomaviruses (HPVs), directly contribute to carcinogenesis through the expression of oncogene proteins, such as E6 and E7 proteins, which regulate multiple pathways such as cellcycle checkpoints and host immune response. It has been suggested that Toll like receptors (TLRs) activation is involved in the pathogenesis of HPV infection and is associated with the carcinogenic processes though a mechanism not yet clear. Methods C33-A carcinoma cervical cells expressing or not e6/e7 genes from high-risk HPV 16 were cultured in the presence of medium or activated with TLR2 or TLR4 agonists (Pam3CSK4 and LPS, respectively) for 24hs. Subsequently, the expression of TLRs, E6 and E7 proteins together with different co-inhibitory molecules were measured using Flow Cytometry and cytokines secreted were measured by ELISA. Results We detected a low TLR4 and TLR2 expression in both cell lines, with no significant differences between C33-A and C33E6E7 cells in either basal or stimulated condition. However, the presence of TLRs agonists induced a significant increase in oncoproteins expression in C33E6E7 cell line. Moreover, a higher PD-L1 expression was observed in C33E6E7 cells compared to C33A cells. This PD-L1 overexpression was even more marked after the stimulation with TLRs ligands. While no differences were detected for IL-8, IL-6, IL-10, INFγ or Il-1β in both cell lines, an increase in TNF was observed during stimulation with TLR2 ligand. Conclusions Cervix is often exposed to the presence of HPV and other numerous microorganisms that could potentially cause inflammation. HPV presence could affect innate activation of epithelial cells locally inducing a high expression of oncoproteins and also co-inhibitory molecules, such as PD-L1, closely related to reduced immune response in both infectious diseases and progression of cervical cancer.