Correlation of IL-31 mRNA expression in PBMCs with the severity of disease and pruritus in children with atopic dermatitis

To investigate the expression of IL-31 in children with intrinsic or extrinsic form of atopic dermatitis(AD) and to explore its correlation with the severity of disease and pruritus as well as its possible mechanisms,28 children with AD and 24 age mached healthy controls were recruited in this study.Various parameters,such as SCORAD,scores of pruritus and sleep loss,total serum IgE,blood eosinophil count,were assessed.Expression of IL-31 mRNA in PBMCs was evaluated by means of quantitative real-time PCR and IL-31RA level and distribution were also detected in skin biopsy specimens by using immunohistochemistry.It was found that the IL-31 mRNA expression in AD children was significantly upregulated,which was much higher than that of in normal controls(P0.05).However,there was no statistical difference in terms of IL-31 expression between intrinsic AD(IAD) and extrinsic AD(EAD).In AD children,the IL-31 expression levels correlated positively with the severity of disease and the degree of pruritus(r=0.495,P0.05;r=0.584,P0.05 respectively).IL-31RA positive staining was found mainly in cytoplasm of keratinocytes and was more pronounced in AD skin compared with that in heathy controls(P0.001).IL-31RA positive staining was also observed in nerve fiber bundle,tunic of Meissner's corpuscles and Pacinian corpuscle in the dermis of AD skin lesion.It is concluded that IL-31 may not be the major immunologic differences between IAD and EAD.However,it contributes to the development of prutitus in AD and could serve as a marker of disease severity in AD.