Expression of neuropeptide in psoriasis in relation to aggravation of symptoms

Abstract

Many clinical evidences suggest the components of nervous system including psychological and neurogenic factors can influence the course of psoriasis. However, the nature of the association between stress and psoriasis remains unclear, in part due to the lack of substantial evidence regarding the participation of cutaneous neurogenic factors in the pathogenesis of psoriasis. To examine the role of neurogenic factors such as neuropeptides in aggravation of psoriasis. We used immunohistochemistry to detect the expression of substance P(SP), nerve growth factor(NGF) and a neuropeptide degrading enzyme such as neutral endopeptidase(NEP) in the lesional skin of psoriasis patients(n=10) and compared them with skin of normal control (n=8). The concentrations of SP and calcitonin gene related peptide(CGRP) in psoriasis patients(n=8) were also measured by enzyme-linked immunosorbent assay and were compared with those of normal controls(n=8). When compared with normal skin, lesional skin of psoriasis patients showed the following characteristic features: (I) strong immunoreactivity for SP and nerve growth factor(NGF) throughout the epidermis and papillary dermis; (ii) increased expression of neutral endopeptidase in the papillary dermis. The difference in the serum concentration of SP in the psoriasis group compared with that in the control group was not significant(P=0.13). However, the serum concentration of CGRP in the psoriasis group was significantly lower than that in the control group(P= 0.001). Therefore, the elevated immunoreactivity of SP, NGF and NEP accompanied with the decreased serum levels of CGRP may play important roles in the pathogenesis of psoriasis.