Novel electrophilic omega‐3 fatty acid derivatives are produced by activated macrophages

Abstract

Docosahexaenoic acid (DHA) is an ω‐3 fatty acid that reduces the risk of heart disease, colon cancer and neurocognitive disorders, with mechanisms of action including the enzymatic and free radical induced oxidation of DHA to signaling mediators. We report a new LC‐MS/MS‐based analysis that identifies the formation of novel electrophilic fatty acid derivatives (EFADs) using β‐mercaptoethanol (BME) trapping and monitoring for the neutral loss of BME (m/z 78). MS analysis of IFNγ and LPS‐activated macrophages (RAW264.7 and THP‐1) reveals that EFADs are mono‐oxidized products of DHA and docosapentaenoic acid. DHA constitutes less than 3 mol % of total fatty acid content and accounts for 90% of detected electrophilic lipids. EFAD production is dependent on the activation of prostaglandin‐H synthase‐2 and independent of phospholipase‐A2 and 5‐lipoxygenase. The formation of electrophilic fatty acids plays an important role in cell signaling by adducting to nucleophilic residues, thus modulating protein function (e.g. NFκB, Keap1/Nrf2 pathways). Here, we report previously undescribed electrophilic metabolites of ω‐3 fatty acids formed by activated macrophages that can be important as autocrine and paracrine signaling mediators during inflammation.