de Bus I, Zuilhof H, Witkamp R, Balvers M, Albada B. Novel COX-2 products of
n-3 polyunsaturated fatty acid-ethanolamine-conjugates identified in RAW264.7 macrophages.
J Lipid Res 2019;
60:1829-1840. [PMID:
31455615 PMCID:
PMC6824491 DOI:
10.1194/jlr.m094235]
[Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 08/09/2019] [Indexed: 12/28/2022] Open
Abstract
Cyclooxygenase 2 (COX-2) plays a key role in the regulation of inflammation by catalyzing the oxygenation of PUFAs to prostaglandins (PGs) and hydroperoxides. Next to this, COX-2 can metabolize neutral lipids, including endocannabinoid-like esters and amides. We developed an LC-HRMS-based human recombinant (h)COX-2 screening assay to examine its ability to also convert n-3 PUFA-derived N-acylethanolamines. Our assay yields known hCOX-2-derived products from established PUFAs and anandamide. Subsequently, we proved that eicosapentaenoylethanolamide (EPEA), the N-acylethanolamine derivative of EPA, is converted into PGE3-ethanolamide (PGE3-EA), and into 11-, 14-, and 18-hydroxyeicosapentaenoyl-EA (11-, 14-, and 18-HEPE-EA, respectively). Interestingly, we demonstrated that docosahexaenoylethanolamide (DHEA) is converted by hCOX-2 into the previously unknown metabolites, 13- and 16-hydroxy-DHEA (13- and 16-HDHEA, respectively). These products were also produced by lipopolysaccharide-stimulated RAW267.4 macrophages incubated with DHEA. No oxygenated DHEA metabolites were detected when the selective COX-2 inhibitor, celecoxib, was added to the cells, further underlining the role of COX-2 in the formation of the novel hydroxylated products. This work demonstrates for the first time that DHEA and EPEA are converted by COX-2 into previously unknown hydroxylated metabolites and invites future studies toward the biological effects of these metabolites.
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