Increased expression of psoriasin (S100A7) and interleukin 17 (IL-17) in lesional skin in lichen planopilaris

Lichen planopilaris (LPP) is an inflammatory, primary scarring alopecia, however its pathogenesis is not completely elucidated. S100A7 is a multifunctional, antimicrobial protein with proinflammatory properties. Interleukin-17 (IL-17) is implicated in the development of various autoimmune skin diseases. To determine the tissue expression of S100A7, S100A4 and IL-17 in LPP. The immunohistochemical analysis was performed on biopsy specimens obtained from individuals with histologically confirmed lichen planopilaris ( = 23), alopecia areata (AA) ( = 11), and healthy controls ( = 14). The expression was evaluated using Zeiss Axio Imager A2 light microscope. The number of cells showing S100A7 expression was significantly higher in LPP lesional skin compared to AA lesional skin ( = 0.0002) and normal skin of healthy controls ( < 0.0001). The number of cells showing IL-17 expression was significantly higher in LPP lesional skin compared to normal skin of healthy controls ( < 0.0001) and the number of cells showing IL-17 expression was significantly higher in AA lesional skin compared to normal skin of healthy controls ( < 0.0001). The number of cells showing IL-17 expression was not significantly different in LPP lesional skin and in AA lesional skin ( > 0.05). The number of cells showing S100A4 expression was not significantly different in LPP lesional skin, AA lesional skin and in normal skin of healthy controls. The results of our study suggest the possible role of S100A7 and IL-17 in the pathogenesis of LPP.