Non-Coding RNAs as Potential Targets for Diagnosis and Treatment of Oral Lichen Planus: A Narrative Review

Abstract

Oral lichen planus (OLP) is a chronic inflammatory disease that is characterized by the infiltration of T cells into the oral mucosa, causing the apoptosis of basal keratinocytes. OLP is a multifactorial disease of unknown etiology and is not solely caused by the malfunction of a single key gene but rather by various intracellular and extracellular factors. Non-coding RNAs play a critical role in immunological homeostasis and inflammatory response and are found in all cell types and bodily fluids, and their expression is closely regulated to preserve normal physiologies. The dysregulation of non-coding RNAs may be highly implicated in the onset and progression of diverse inflammatory disorders, including OLP. This narrative review summarizes the role of non-coding RNAs in molecular and cellular changes in the oral epithelium during OLP pathogenesis.

Keywords: T lymphocyte; circular RNA; inflammation; long non-coding RNA; microRNA; oral lichen planus.

Figure 1

T cells–keratinocyte interaction in OLP. Upon stimulation, CD4+ T cells differentiate into Th1, Th2, Th17, and Treg subtypes. Th1-dominant imbalance of Th1/Th2 cytokine activates cytotoxic CD8+ T cells. Keratinocyte apoptosis can be stimulated in various ways, including antigen presentation, FAS-FASL interaction, T cell-derived cytotoxic substances, and exosomes.

Figure 2

Underlying molecular mechanisms of miR-146a in the microenvironment of OLP. Foxp3 can induce the expression of miR-146a in both Tregs and keratinocytes. miR-146a mediates inflammatory response, proliferation, and apoptosis by targeting IRAK1 and TRAF6.

Figure 3

Sequence and expression analysis of FABP5P3. (A) Sequence comparison between FABP5P3 and FABP5, generated using Multalin [155]. (B) Predicted RNA secondary structures for the lncRNA FABP5P3 and FABP5 mRNA, based on free energy calculations via mfold program. (C) Expression of FABP5P3 across tissues, taken from the GTEx Portal. TPM, transcripts per million. (D) FABP5P3 and FABP5 expression in normal oral and OLP epithelium. Data were extracted and analyzed from the NCBI GEO profile database (GEO accession: GSE52130). Expression was normalized with that of ACTB. Statistical significance was determined by unpaired t-test. * p < 0.05 and ** p < 0.01.

Figure 4

PRINS, G1P3, and NPM1 expression in normal oral and OLP epithelium. Expression of PRINS, G1P3, and NPM1 was analyzed. Data were extracted and analyzed from the NCBI GEO profile database (GEO accession: GSE52130). Expression was normalized with that of ACTB. Statistical significance was determined by unpaired t-test. * p < 0.05. n.s., not significant.