Expression of Neuropeptides, Neurotrophins, and Neurotransmitters in the Skin of Patients with Atopic Dermatitis and Psoriasis.

Expression of neural marker PGP9.5, amphiregulin, semaphorin-3A, calcitonin gene-related peptide and its receptor, nerve growth factor and its receptor, substance P and its receptor, and expression frequency were analyzed in biopsy specimens from patients with atopic dermatitis and psoriasis and healthy volunteers by immunohistochemical method. Nerve fibers penetrated into the epidermis more frequently, and amphiregulin expression was significantly higher in patients with atopic dermatitis and psoriasis comparing to the control. Expression of semaphorin-3A in patients with atopic dermatitis was less frequent than in the control. These findings reflect the involvement of amphiregulin and semaphorin-3A in the improvement of skin innervations and penetration of nerve fibers into the epidermis, and due of which these proteins mediate the development of itch.