Molecular Mechanism of Atopic Dermatitis Induction Following Sensitization and Challenge with 2,4-Dinitrochlorobenzene in Mouse Skin Tissue

Laboratory animal models have been developed to investigate preventive or therapeutic effect of medicinal products, or occurrence or progression mechanism of atopic dermatitis (AD), a pruritic and persistent inflammatory skin disease. The murine model with immunologic phenomena resembling human AD was introduced, which demonstrated skewedness toward predominance of type-2 helper T cell reactivity and pathophysiological changes similar as human AD following 2,4-dinitrochlorobenzene (DNCB) sensitization and challenge. Molecular mechanism on the DNCB-mediated AD was further evaluated. Skin tissues were collected from mice treated with DNCB, and each tissue was equally divided into two sections; one for protein and the other for mRNA analysis. Expression of filaggrin, an important protein for keratinocyte integrity, was evaluated through SDS-PAGE. Level of mRNA expression for cytokines was determined through semi-quantitative reverse transcriptase polymerase chain reaction. Expression of filaggrin protein was significantly enhanced in the mice treated with DNCB compared with the vehicle (acetone : olive oil = 4 : 1 mixture) treatment group or the normal group without any treatment. Level of tumor necrosis factor-alpha and interleukin-18 mRNA expression, cytokines involved in activity of type-1 helper T (T(H)1) cell, was significantly downregulated in the AD group compared with other control groups. These results suggest that suppression of T(H)1 cell-mediated immune response could be reflected into the skin tissue of mice treated with DNCB for AD induction, and disturbance of keratinocyte integrity might evoke a compensatory mechanism.