Chronic mouse model of TMA-induced contact hypersensitivity.

Due to the steadily increasing incidence of atopic dermatitis (AD), especially in children, there is a high medical need for new therapies and improved animal models. In mice, trimellitic anhydride (TMA) is routinely used to trigger T-cell-dependent contact hypersensitivity (CHS) reactions. In this study, we compared the standard acute TMA-induced CHS in Balb/c mice with subacute and chronic models of TMA-induced ear inflammation. Compared to the acute model, the chronic CHS model more closely reflects characteristics of AD, such as typical morphological changes of the inflamed skin, strong infiltration with T cells, major histocompatibility complex II-positive cells, eosinophils, and mast cells, a T-helper cell-type (Th) 2 cytokine profile and a strong increase of serum IgE levels. Moreover, a strong lymph node involvement with T-helper cell dominance and a mixed Th1/Th2 T-cell differentiation and activation pattern was demonstrated. Importantly, as demonstrated by successful therapy with prednisolone, the chronic TMA-induced CHS model, in contrast to acute and subacute models, made prolonged therapeutic treatment of a pre-established skin inflammation possible. Altogether, we present an improved model of mouse T-cell-dependent skin inflammation for AD. We hope this model will enhance the predictive value of animal models for therapeutic treatment of atopic eczema.