LAUSR

Abstract The present research was designed to evaluate the protective effects and underlying mechanisms of different ratios of linoleic acid (LA) and α-linolenic acid (ALA), two essential polyunsaturated fatty acids (PUFAs) fatty acids, on atopic dermatitis (AD)-like skin lesions induced by 2, 4-dinitrofluorobenzene (DNFB). The dorsal flank and ear pinnas of mice were sensitized and challenged with DNFB for four weeks in order to establish AD model. Simultaneously, the mice were orally administered different ratios of LA/ALA (v/v; 4:1 or 1:1), or dexamethasone (Dex; 0.1 mg/kg). Results showed that different LA/ALA ratios, especially a ratio of 4:1 treatment, could effectively ameliorate DNFB-induced skin lesions, ear edema, scratching behavior and skin inflammation, as reflected by the reduced inflammatory blood cells, IgE serum levels, and skin levels of the pro-inflammatory lipid mediators, including PGE2 and LTB4. These findings were further confirmed by skin pathological examination. Moreover, LA/ALA administration markedly suppressed the proliferation and infiltration of T cells, the production of T helper cell type 1 (Th1), Th2 and Th17 cytokines in dorsal skin and serum of DNFB-treated mice. Western blotting and immunohistochemistry staining revealed that LA/ALA downregulated the protein expressions of JAK2 and STAT4, and thus reducing the synthesis of type Th1 cytokine IFN-γ. Taken together, these results suggest that optimal nutrition ratio of LA/ALA has beneficial effects on AD-like symptoms, which provide theoretical basis for its therapeutic potential in the clinical prevention and treatment of AD.