IL-17A immune pattern across genetic acantholytic and blistering disorders.

There is a high therapeutic need for acantholytic and blistering genodermatoses. Cutaneous inflammation is a reasonable target, although the patterns are not yet fully elucidated. Here we investigated by immunohistochemistry whether IL-17A is expressed in the inflammatory infiltrate in 34 patients with Hailey-Hailey disease, Darier disease, junctional and dystrophic epidermolysis bullosa. There was a 5-7-fold increase in the number IL-17A positive cells in all patients' samples as compared to the normal skin. IL-17A cells were present in the epidermal acantholytic areas and dermal inflammatory infiltrates in Hailey-Hailey and Darier disease. In epidermolysis bullosa samples positive cells were present at the dermal-epidermal junction zone. The IL-17A inflammatory pattern was validated by upregulation of downstream genes/proteins, S100A7, S100A8 and S100A9. These results suggest that IL-17A contributes to skin inflammation and could be a therapeutic target during inflammatory flares in these disorders.