Involvement of IL‐31 on scratching behavior in NC/Nga mice with atopic‐like dermatitis

Publisher Website
Google Scholar
Abstract
Abstract:  Pruritus is an important symptom in atopic dermatitis (AD), but the major pruritogen have not been identified. NC/Nga mice, spontaneously develop an eczematous AD‐like skin lesion when kept under conventional conditions, but not under specific pathogen‐free (SPF) conditions, have been thought to be an animal model for AD. In this study, to determine whether newly identified cytokine, IL‐31, may be involved in pruritus of AD, we examined the IL‐31 expression in spontaneous dermatitis model which showed itch‐associated long‐lasting (over 1.5 s duration) scratching behavior and compared with that of hapten‐induced contact dermatitis model without itch‐associated long‐lasting scratching behavior, using NC/Nga mice. In NC/Nga mice cohabited with NC/Nga mice which developed severe dermatitis for 2 weeks (conventional NC/Nga mice), the numbers of long‐lasting scratching counts were significantly increased. Yet in 2,4,6‐trinitrochlorobenzene (TNCB)‐sensitized and challenged mice (TNCB‐applied NC/Nga mice), no significant increase in long‐lasting scratching counts was observed. In conventional NC/Nga mice with long‐lasting scratching behavior, expression of IL‐31 mRNA was increased, while in TNCB‐applied NC/Nga mice without long‐lasting scratching behavior, the expression of IL‐31 mRNA were unchanged. There was a good correlation between the scratching counts and expression of IL‐31 mRNA in conventional NC/Nga mice, but not so in TNCB‐applied NC/Nga mice. These results suggest that IL‐31 causes the itch‐associated scratching behavior in conventional NC/Nga mice, an experimental animal model for AD.