Atopic dermatitis (AD) is caused by both dysregulated immune responses and an impaired skin barrier. Although
leukotriene B4 (
LTB4) is involved in tissue
inflammation that occurs in several disorders, including AD, therapeutic strategies based on
LTB4 inhibition have not been explored. Here we demonstrate that progression of an AD-like
skin disease in NC/Nga mice is inhibited when
docosahexaenoic acid (DHA)/
eicosapentaenoic acid (EPA) is administered together with
FK506. Treatment with DHA/EPA and
FK506 decreases the clinical score of
dermatitis in NC/Nga mice and lowers local
LTB4 concentrations. The treatment also suppressed the infiltration of T cells, B cells, eosinophils and neutrophils, and promoted reduced serum
IgE levels. Secretion of
IL-13 and
IL-17A in CD4(+) T cells was lower in DHA/EPA- and FK506-treated mice than in mice treated with
FK506 alone. The inhibition of
disease progression induced by DHA/EPA was reversed by local injection of
LTB4, suggesting that the
therapeutic effect of DHA/EPA is LTB4-dependent. Our results demonstrate that treatment of AD with DHA/EPA is effective for allergic skin
inflammation and acts by suppressing
LTB4 production. J. Med. Invest. 63: 187-191, August, 2016.