Toll-like receptor 2: a possible role in the pathogenesis of oral lichen planus and hepatitis C virus infection, a case–control study

Background Toll-like receptor 2 (TLR2) is a pathogen recognition pattern that may play a role in the pathogenesis of both oral lichen planus (OLP) and hepatitis C virus (HCV) infection. Objective To investigate a potential role of TLR2 in the pathogenesis of OLP with or without HCV infection and in HCV infection ‘without OLP’. Patients and methods This case–control study included three groups: OLP group (20 patients: 12 HCV positive and eight HCV negative patients), HCV positive group ‘without OLP’ (20 patients) and healthy control group (20 subjects). TLR2 expression levels on peripheral blood monocytes (PBMCs) were measured in all participants by flow cytometric analysis. Results TLR2 expression on PBMCs was significantly higher in both the OLP group and the HCV positive group ‘without OLP’ than in healthy controls (P ≤0.001) but was nearly equal in both the OLP and HCV group ‘without OLP’. Although TLR2 expression was higher in HCV positive than in HCV negative OLP cases, the difference did not reach statistical significance. Conclusion The increased TLR2 expression on PBMCs is probably involved in the pathogenesis of OLP with or without HCV infection, as well as in the pathogenesis of HCV infection ‘without OLP’. The idea that TLR2 can be the gate by which HCV induces OLP cannot be verified by this study.