Increased expression of heat shock protein 90 in keratinocytes and mast cells in patients with psoriasis

Background: Psoriasis is a chronic inflammatory skin disease and various stress factors mediate inflammation. Heat shock protein (HSP) 90 plays an important role in cell survival; cytokine signaling, such as interleukin-17 receptor signaling; and immune responses. Objective: We sought to elucidate protein expression and distribution of HSP90 in psoriasis. Methods: HSP90 expression and its cellular source were analyzed on normal-appearing, nonlesional, lesional, and ustekinumab-treated psoriatic skin using immunohistochemistry and double immunofluorescence. Results: HSP90 alpha, the inducible isoform of HSP90, was significantly up-regulated in epidermal keratinocytes and mast cells of lesional skin and down-regulated after ustekinumab therapy. Limitations: There was a limited sample size. Conclusions: HSP90 from keratinocytes and mast cells is a key regulator of psoriatic inflammation and HSP90 inhibitors may represent a novel therapeutic approach to the disease.