Calcitonin gene-related peptide in Langerhans cells in psoriatic plaque lesions

Objective To study the mechanism of stress exacerbating psoriasis and the involvement effect of neuropeptides in psoriatic pathogenesis, we investigated the expression and secretion of calcitonin gene-related peptide (CGRP) in psoriatic lesions, then identified the target cells of CGRP , the characters of CGRP positive dendrite cells and the source of CGRP in psoriatic plaque lesions.
Methods Specific radioimmunoassay (RIA) and immunohistochemistry staining methods were used to determine CGRP secretive content and the target cells of CGRP in psoriatic plaque lesion tissue of vulgaris psoriasis. Double immunofluorenscence staining was done on psoriatic plaque lesion sections by first using rabbit anti-human CGRP antibody and mouse anti-human CD1a antibody, second using PE-conjugated anti-mouse immunoglobulin and FITC-conjugated anti-rabbit immunoglobulin. Confocal laser microscope showed the psoriatic lesion sections. Then both digoxigenin labelled anti-sense and sense RNA probe of CGRP were synthesized to make sure the source of CGRP on the dendrite cells. The psoriatic lesion sections were studied by in situ hybridization.
Results The content of CGRP in vulgaris psoriatic plaque lesions was higher than that of normal controls (P<0.01). CGRP was also found on the dermal microvascular endothelial cells and the epidermal dendrite cells in psoriatic plague lesions. Further study showed that CGRP existed on the surface of epidermal CD1a + Langerhans cell in psoriatic plaque lesion. The CGRP mRNA expressed around the nucleus of the Langerhans cells in psoriatic lesion.
Conclusions The pathogenesis of psoriatic plaque lesions was closely related to the overexpression of neuropeptide CGRP. The CGRP contacted with the dermal microvascular endothelial cells and epidermal dendrite cells in psoriatic plaque lesion. The CGRP positive epidermal dendrite cell was CD1a + Langerhans cell. The Langerhans cell itself expressed CGRP mRNA.