TCDD exposure exacerbates atopic dermatitis-related inflammation in NC/Nga mice

Our previous study showed that 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure of NC/Nga mice, a mouse model of atopic dermatitis, induces no dermal changes. In the present study, to investigate whether TCDD exacerbates atopic dermatitis-like skin lesions elicited in NC/Nga mice, NC/Nga mice were applied with picryl chloride (PC), and then were exposed to a single oral dose of 0 (control), 5, and 20 μg TCDD/kg. Two weeks later, spleens, blood, and skin specimens were collected. TCDD exposure increased the production of Th1-type cytokine IFN-γ, but not Th2-type cytokine IL-4, from spleen cells stimulated with a mitogen. The plasma total IgE antibody levels of the TCDD-exposed mice remained at control levels. On the other hand, TCDD exposure markedly increased the mast cell infiltration and degranulation in PC-sensitized NC/Nga mice histologically, as compared with control mice. These results suggest that TCDD exposure exacerbates atopic dermatitis-related inflammation with no increase of IgE antibody production and that TCDD may be one of the environmental pollutants that induce exacerbations of atopic diseases.