Possible Antipruritic Mechanism of Cyclosporine A in Atopic Dermatitis.

Cyclosporine A is an immunosuppressive agent that suppresses pruritus and is currently used in the treatment of patients with severe atopic dermatitis. The aim of this study was to elucidate the antipruritic mechanism of cyclosporine A using a mouse model of atopic dermatitis. Intraperitoneal injection of cyclosporine A (5 mg/kg) significantly reduced epidermal nerve density, number of scratching bouts, dermatitis scores, and transepidermal water loss, as well as decreasing the numbers of inflammatory cells in the dermis and decreasing epidermal thickness. Intraperitoneal injection of cyclosporine A dose-dependently inhibited increased itch-related receptor gene expression, such as interleukin-31 receptor A and neurokinin-1 receptor, in the dorsal root ganglion of atopic dermatitis model mice. Thus, the antipruritic efficacy of cyclosporine A may involve reduced epidermal nerve density and expression levels of itch-related receptor genes in the dorsal root ganglion, as well as improvement in acanthosis and reduction in cutaneous inflammatory cell number.