Omega-3 fatty acids suppress Th2-associated cytokine gene expressions and GATA transcription factors in mast cells

Because the interaction between omega-3 fatty acids and mast cells has remained largely unknown in allergies, we investigated whether omega-3 fatty acids affect the activation of mast cells by examining Th2-associated cytokine production and possible molecular mechanisms. Alpha-linolenic acid and its metabolites including eicosapentaenoic acid and decosahexaenoic acid induced a dramatic decrease in the production of interleukin (IL)-4, IL-5 and IL-13 in a dose-dependent manner, as well as mRNA expression of their genes, in activated MC/9 mast cells and bone marrow-derived mast cells. The effects were comparable to those of cyclosporin A (1 μM), a well-known immunosuppressive agent. Nuclear expression of GATA binding protein-1 (GATA-1) and GATA binding protein-2 (GATA-2), essential transcription factors for mast cell activation, was also greatly suppressed. However, their mRNA expressions were not affected. In P815 mast cells, which do not express GATA-1, the suppressive effects on cytokines were abolished. On the contrary, omega-3 fatty acids had less significant effects on IL-4 and IL-5 and resulted in a slight decrease in IL-13 production in EL-4 T cells. Finally, oral administration of fish oil containing high level of omega-3 fatty acids significantly reduced the severity of dermatitis and the thickening of epidermis/dermis in a NC/Nga murine atopic model. The number of cells expressing CD117⁺ and FcεRIα⁺ was greatly decreased and GATA-1 expression in the cells was also diminished. Taken together, omega-3 fatty acids might target mast cells to a greater extent than T cells to suppress Th2 cytokine expression by inhibiting GATAs for alleviation of allergic disease.