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Previous clinical trials have addressed the beneficial effects of fish oil supplementation on atopic dermatitis. Recently, we reported that fat-1 mice, which can convert n-6 to n-3 polyunsaturated fatty acids (PUFAs), are protected against allergic airway inflammation because their Th2 immune responses are suppressed. Here, we examined the effects of endogenously synthesized n-3 PUFAs on atopic dermatitis, a representative Th2-dominant allergic inflammatory disease. Mouse models of atopic dermatitis-like skin lesions were prepared by epicutaneous application of 2,4-dinitrochlorobenzene (DNCB) or house dust mite (HDM) extract to the ears. DNCB-treated fat-1 mice exhibited markedly reduced epidermal thickening, lower mast cell infiltration, and lower serum IgE and histamine compared with wild-type mice. The draining lymph nodes of fat-1 mice were substantially smaller and contained significantly smaller proportions of activated CD4+ T cells and IL-4-producing Th2 cells than those of wild-type mice. Consistent with these findings, the mRNA levels of Th2 cytokines were significantly decreased in DNCB-sensitized skin lesions of fat-1 mice. Lastly, inflammasome activation, IL-1β production, and pyroptotic cell injury were suppressed in fat-1 mice. Similar results were observed in HDM-challenged fat-1 mice. This study confirms the results of previous clinical studies and suggests fish oil supplementation as a therapeutic strategy for atopic dermatitis-like skin lesions.
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