Docosahexaenoic acid (DHA, C22:6) is highly enriched in brain, synapses, and retina and is a major -3 fatty acid. Deficiencies in this essential fatty acid are reportedly associated with neuronal function, cancer, and inflammation. Here, using new lipidomic analyses employing high performance liquid chromatography coupled with a photodiode-array detector and a tandem mass spectrometer, a novel series of endogenous mediators was identified in blood, leukocytes, brain, and glial cells as 17S-hydroxy-containing docosanoids denoted as docosatrienes (the main bioactive member of the series was 10,17S-docosatriene) and 17S series resolvins. These novel mediators were biosynthesized via epoxide-containing intermediates and proved potent (pico-to nanomolar range) regulators of both leukocytes reducing infiltration in vivo and glial cells blocking their cytokine production. These results indicate that DHA is the precursor to potent protective mediators generated via enzymatic oxygenations to novel docosatrienes and 17S series resolvins that each regulate events of interest in inflammation and resolution.

Aspirin (ASA) is unique among current therapies because it acetylates cyclooxygenase (COX)-2 enabling the biosynthesis of R-containing precursors of endogenous antiinflammatory mediators. Here, we report that lipidomic analysis of exudates obtained in the resolution phase from mice treated with ASA and docosahexaenoic acid (DHA) (C22:6) produce a novel family of bioactive 17R-hydroxy-containing di- and tri-hydroxy-docosanoids termed resolvins. Murine brain treated with aspirin produced endogenous 17R-hydroxydocosahexaenoic acid as did human microglial cells. Human COX-2 converted DHA to 13-hydroxy-DHA that switched with ASA to 17R-HDHA that also proved a major route in hypoxic endothelial cells. Human neutrophils transformed COX-2-ASA–derived 17R-hydroxy-DHA into two sets of novel di- and trihydroxy products; one initiated via oxygenation at carbon 7 and the other at carbon 4. These compounds inhibited (IC50 ∼50 pM) microglial cell cytokine expression and in vivo dermal inflammation and peritonitis at ng doses, reducing 40–80% leukocytic exudates. These results indicate that exudates, vascular, leukocytes and neural cells treated with aspirin convert DHA to novel 17R-hydroxy series of docosanoids that are potent regulators. These biosynthetic pathways utilize omega-3 DHA and EPA during multicellular events in resolution to produce a family of protective compounds, i.e., resolvins, that enhance proresolution status.

1 Lipoxins (LX) and aspirin-triggered 15-epi-lipoxins (ATL) exert potent anti-inflammatory actions. In the present study, we determined the anti-inflammatory efficacy of endogenous LXA 4 and LXB 4 , the stable ATL analog ATLa2, and a series of novel 3-oxa-ATL analogs (ZK-996, ZK-990, ZK-994, and ZK-142) after intravenous, oral, and topical administration in mice. 2 LXA 4 , LXB 4 , ATLa2, and ZK-994 were orally active, exhibiting potent systemic inhibition of zymosan A-induced peritonitis at very low doses (50 ng kg À1-50 mg kg À1 ). 3 Intravenous ZK-994 and ZK-142 (500 mg kg À1) potently attenuated hind limb ischemia/ reperfusion-induced lung injury, with 32712 and 5375% inhibition (Po0.05), respectively, of neutrophil accumulation in lungs. The same dose of ATLa2 had no significant protective action. 4 Topical application of ATLa2, ZK-994, and ZK-142 (B20 mg cm À2) prevented vascular leakage and neutrophil infiltration in LTB 4 /PGE 2 -stimulated ear skin inflammation. While ATLa2 and ZK-142 displayed approximately equal anti-inflammatory efficacy in this model, ZK-994 displayed a slower onset of action. 5 In summary, native LXA 4 and LXB 4 , and analogs ATLa2, ZK-142, and ZK-994 retain broad antiinflammatory effects after intravenous, oral, and topical administration. The 3-oxa-ATL analogs, which have enhanced metabolic and chemical stability and a superior pharmacokinetic profile, provide new opportunities to explore the actions and therapeutic potential for LX and ATL.