Omega‐3 Fatty Acids Cause Dramatic Changes in TLR‐4 and Purinergic Eicosanoid Signaling in Macrophages

Abstract

Dietary fish oil omega‐3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), elicit cardioprotective and anti‐inflammatory effects through unresolved mechanisms. EPA and DHA may reduce arachidonic acid (AA) metabolism and pro‐inflammatory effects by competition and inhibition at multiple levels. Here, we report the effects of AA, EPA, and DHA supplementation on membrane incorporation, phospholipase A2 release, and eicosanoid production in RAW264.7 macrophages. Each PUFA supplemented increased by similar amounts in membrane phospholipids, while half of the increased AA and EPA were elongated to adrenic acid (AdA) and docosapentaenoic acid (DPA), respectively; and were subsequently released by PLA2 at levels comparable to AA. TLR‐4 stimulated COX‐2 AA production did not increase with AA supplementation and was inhibited by 20% and 50% after EPA and DHA supplementation, respectively. ATP stimulated COX‐1 AA production was inhibited to a greater extent by EPA and DHA; 5‐LOX AA metabolites increased 2‐fold with EPA and DHA supplementation, and 5‐LOX metabolized EPA and DHA to a greater extent than COX‐1/COX‐2. Altogether, AA, EPA and DHA supplementation decreased TLR‐4 stimulated AA COX‐2 prostanoid metabolism; increased the purinergic stimulated AA 5‐LOX/COX‐1 ratio; and significantly increased elongated PUFA levels that may be converted to novel mediators.