EXPRESSION OF NERVE GROWTH-FACTOR RECEPTORS IN CUTANEOUS INFLAMMATION

Evidence indicates that the neurotrophin nerve growth factor (NGF) is a mediator of cutaneous inflammatory responses, Cellular responses to NGF are facilitated by two receptors called trk A and p75 neurotrophin receptor (p75(NTR)), In the current study we have investigated the ex pression of these receptors in lesional and non-lesional skin from pat ients with plaque psoriasis and in normal skin exposed to three times the minimal erythema dose of ultraviolet (UV) B radiation, Trk a immun ostaining was confined to the basal keratinocytes in normal skin. Ther e was a significant reduction in trk A immunostaining in both non-lesi onal and lesional psoriatic skin compared with control skin. In UVB-ir radiated normal skin, there was a significant reduction in trk A immun ostaining at 4 h after irradiation, which was still evident at 48 h, I n normal skin, p75(NTR) immunopositive fine nerve fibres were present throughout the dermis and occasionally seen in the epidermis. Thick ne rve fibres were evident in the deep dermis and in the middle region of the dermis, p75(NTR) immunopositive basal keratinocytes were occasion ally seen. There was a statistically significant loss of p75(NTR) immu nopositive fine nerve fibres in the epidermis of lesional psoriatic sk in and a statistically significant loss of p75(NTR) immunopositive fin e nerve fibres in the dermis in both nonlesional and lesional psoriati c skin. p75(NTR) immunopositive thick nerve fibres were reduced in les ional psoriatic skin compared with normal skin. UVB irradiation of nor mal skin led to a statistically significant decrease in the p75(NTR) i mmunopositive fine nerve fibres in the epidermis at 48 h after irradia tion. There was no significant reduction in the dermal p75(NTR) immuno reactivity. These results demonstrated that expression of both NGF rec eptors is decreased following an acute inflammatory stimulus and also in association with a chronic inflammatory dermatosis.