Forkhead box p3 controls progression of oral lichen planus by regulating microRNA-146a

Oral lichen planus (OLP) is a severe T cell-mediated disorder of the mucosa, which causes chronic inflammation. Forkhead box P3 (Foxp3) regulates the immune response and plays an important role in immunological diseases. The current study aimed to determine the role of Foxp3 and microRNA (miR)-146a in OLP. Western blot analysis and a quantitative real-time polymerase chain reaction assay showed that the expression of Foxp3 and miR-146a was upregulated in OLP tissues and in lipopolysaccharide (LPS)-incubated HaCaT cells, compared with controls. Foxp3 inhibition significantly decreased miR-146a expression, ameliorated LPS stimulation by decreased cell proliferation, and apoptosis in LPS-incubated HaCaT cells as compared with the LPS group. Cotransfection of Foxp3 small interfering RNA and miR-146a mimics elevated cell proliferation and apoptosis compared with the Foxp3 small interfering RNA group. In addition, miR-146a overexpression upregulated, whereas miR-146a inhibition downregulated, the proliferation and apoptosis of LPS-incubated HaCaT cells. The target gene of miR--146a, tumor necrosis factor receptor-associated factor 6 (TRAF6), was predicted by bioinformatics software and identified by the luciferase reporter assay. Furthermore, Foxp3/miR-146a elevated T regulatory cells and regulated TRAF6 expression in CD4⁺ T cells that were isolated from peripheral blood of patients with OLP. In conclusion, our study suggests that Foxp3 and miR-146a regulate the progression of OLP by negatively regulating TRAF6, which may provide a promising therapeutic target for OLP treatment.