Differential proteomic expression profiles in vulvar lichen planus as compared to normal vulvar tissue, vulvar lichen sclerosus, or oral lichen planus: An exploratory study

Vulvar lichen planus (VLP) is a chronic inflammatory disease which adversely affects patients' quality of life. The pathogenesis of VLP is unknown although Th1 immune response has been implicated. We aimed to discover specific tissue-based protein biomarkers in VLP compared to normal vulvar tissue (NVT), vulvar lichen sclerosus (VLS) and oral lichen planus (OLP). We used laser capture microdissection-liquid chromatography- tandem mass spectrometry to assess protein expression in fixed lesional mucosal specimens from patients with VLP (n = 5). We then compared proteomic profiles against those of NVT (n = 4), VLS (n = 5), OLP (n = 6) and normal oral mucosa (n = 5), previously published by our group. IL16, PTPRC, PTPRCAP, TAP1 and ITGB2 and were significantly overexpressed in VLP compared to NVT. Ingenuity pathway analysis identified antigen presentation and integrin signalling pathways. Proteins overexpressed in both VLP versus NVT and OLP versus NOM included IL16, PTPRC, PTPRCAP, TAP1, HLA-DPB1, HLA-B and HLA-DRA. This proteomic analysis revealed several overexpressed proteins in VLP that relate to Th1 autoimmunity, including IL16. Overlapping pathways, including those involving IFNγ and Th1 signalling, were observed between VLP, VLS, and OLP.