In HPV-negative oropharyngeal squamous cell carcinoma, elevated toll-like receptor 2 immunoexpression may increase the risk of disease-specific mortality.

Objectives: In oropharyngeal squamous cell carcinoma (OPSCC), toll-like receptors (TLR) 5 and 7 associate with the tumor's human papilloma virus (HPV) status (Jouhi et al., 2017). TLR 2, on the other hand, has been linked to head and neck squamous cell carcinoma (HNSCC), and to oral carcinogenesis (Farnebo et al., 2015; Binder Gallimidi et al., 2015). Here we investigated the presence of TLR 2 and 4 in HPV-positive and HPV-negative OPSCC, and their relationship to opportunistic oral pathogen Treponema denticola chymotrypsin-like protease (Td-CTLP) immunoexpression, clinical parameters, and patient outcome.

Materials And Methods: Clinicopathological data of 198 unselected consecutive OPSCC patients came from hospital registries. Immunoexpression of TLRs 2 and 4 we evaluated by immunohistochemistry, and earlier in this patient series we studied immunoexpression of Td-CTLP and HPV DNA, HPV mRNA, and p16 status.

Results: Immunoexpression of both TLRs 2 and 4 showed a significant association with HPV-status. Strong expression was associated with HPV-positivity and mild expression with HPV-negativity. Patients with strong TLR 2 immunoexpression in the HPV negative subgroup had significantly poorer 5-year DSS (58%) than did patients with mild TLR 2 expression (77%), and strong TLR 2 immunoexpression remained as an independent factor linked to increased disease mortality in the multivariable setting (P = 0.019). No association existed between TLR 2 or 4 and Td-CTLP expression.

Conclusion: Our results support the role of TLR 2 receptor as a possible target for development of therapeutics as earlier proposed (Farnebo et al., 2015). The involvement of Td and other oral pathogens in carcinogenesis of OPSCC, remains open and calls for further study.