Oral lichen planus: A chronic inflammatory model to study the regulation of the Toll-like receptor signaling in oral keratinocytes

Background: Oral lichen planus (OLP) is a chronic inflammatory disease with a strong immune mechanism involved. Although no causal factor is identified in OLP, a cellular hypersensitivity has been associated with its pathophysiology. Furthermore, the chronicity of the disease could cause its malignant transformation. Highlight: Herein, we present a literature review focusing on the interrelationship of Toll-like receptors (TLRs) and OLP, mainly on the molecular behavior of oral keratinocytes once TLR signals are activated. A family of transcription factors, the Interferon Regulatory Factor (IRF) family, could be having a novel role in the prognosis of OLP. Specifically, Interferon Regulatory Factor 6 (IRF6) as a key component of the TLR signaling could impart specificity to downstream responses in oral keratinocytes. Conclusion: We propose a hypothetical model after TLR2 activation in which a plausible TLR2-IRF6 regulatory mechanism could be a key factor to be evaluated in OLP as a convenient chronic inflammatory model. Further molecular studies are required to fully understand the role of oral keratinocytes in the initiation of OLP. (C) 2020 Japanese Association for Oral Biology. Published by Elsevier B.V. All rights reserved.