Quantitative analysis of nerve growth factor (NGF) in the atopic dermatitis and psoriasis horny layer and effect of treatment on NGF in atopic dermatitis

Summary Background and objective The expression of nerve growth factor (NGF) is known to increase in the skin of patients with atopic dermatitis (AD) and is related to disease aggravation. In the present study, we measured skin NGF levels in AD patients and determined whether they correlate to AD severity as well as treatment effects. Methods NGF in the horny layer (horn NGF) of skin lesions found on the cubital fossa of AD patients was collected via tape stripping and measured using ELISA before and after 2 and 4 weeks following initiation of treatments. Itching and eruptions on the lesions were also evaluated. Peripheral blood eosinophil count, serum LDH level and total serum IgE level were also examined. Results The level of NGF was significantly higher in AD patients than in healthy controls, and correlated with the severity of itch, erythema, scale/xerosis, eosinophil count, and LDH level. The NGF level decreased significantly at 2 and 4 weeks of treatment with olopatadine, a histamine H1 receptor antagonist, and/or topical steroid. The reduction in NGF correlated with the decrease in the severity of itching and erythema, papule, scale/xerosis and lichenification of the lesion, eosinophil count, and LDH level. In psoriatic lesional skin with itch, the horn NGF was significantly higher than in non-lesional skin of psoriasis, but the value was lower than NGF in atopic skin. Conclusions The level of horn NGF was found to reflect the severity of itching and eruptions in AD. Therefore, quantification of NGF in the samples collected directly from the horny layer appears to be useful in assessing severity and therapeutic effects in AD.