Regulatory T-cells and IL17A+ cells infiltrate oral lichen planus lesions

Oral lichen planus (OLP) is a complex immunological disorder, mediated in part by the release of cytokines from activated T-cells. Of late, two closely related T-helper (Th) cell subsets; regulatory T-cells (Tregs; FoxP3(+)) and Th17 cells (IL17(+)) have been described in various chronic inflammatory diseases. The aim of this study was to determine the expression of FoxP3 and IL17 in OLP using immunohistochemistry (IHC) and quantitative real-time reverse transcriptase polymerase chain reaction (qPCR). For IHC, formalin fixed, paraffin embedded archival specimens, an OLP group (n=10) and a non-specific inflammatory (NSI) control group (n=9) were used. In addition, 12 fresh tissue samples were used to determine gene expression of FoxP3 and IL17. Significantly more FoxP3(+) cells were present in OLP than in NSI. IL17(+) cells were significantly more frequent in the control tissues than in OLP. The gene expression experiments revealed a significantly higher expression of FoxP3 in OLP when compared to the controls. IL17 gene expression was not different between the groups. Double labelling immunofluorescence indicated co-localisation of IL17 with tryptase(+) mast cells. These findings suggest FoxP3(+) Tregs have a more prominent role in the pathogenesis of OLP when compared to IL17(+)cells.