Inhibition of COX-2-mediated eicosanoid production plays a major role in the anti-inflammatory effects of the endocannabinoid N-docosahexaenoylethanolamine (DHEA) in macrophages.
OBJECTIVE
N-docosahexaenoylethanolamine (DHEA) is the ethanolamine conjugate of the long-chain polyunsaturated n-3 fatty acid docosahexaenoic (DHA; 22: 6n-3). Its concentration in animal tissues and human plasma increases when diets rich in fish or krill oil are consumed. DHEA displays anti-inflammatory properties in vitro and was found to be released during an inflammatory response in mice. Here, we further examine possible targets involved in the immune-modulating effects of DHEA.


METHODS
Antagonists for cannabinoid (CB)1 and CB2 receptors and PPARγ were used to explore effects of DHEA on NO release by LPS-stimulated RAW264.7 cells. The possible involvement of CB2 receptors was studied by comparing effects in LPS-stimulated peritoneal macrophages obtained from CB2 (-/-) and CB2 (+/+) mice. Effects on NF-κB activation were determined using a reporter cell line. To study DHEA effects on COX-2 and lipoxygenase activity, 21 different eicosanoids produced by LPS-stimulated RAW264.7 cells were quantified by LC-MS/MS. Finally, effects on mRNA expression profiles were analysed using gene arrays followed by Ingenuity(®) Pathways Analysis.


RESULTS
CB1 and CB2 receptors or PPARs were not involved in the effects of DHEA on NO release. NF-κB and IFN-β, key elements of the myeloid differentiation primary response protein D88 (MyD88)-dependent and MyD88-independent pathways were not decreased. By contrast, DHEA significantly reduced levels of several COX-2-derived eicosanoids. Gene expression analysis provided support for an effect on COX-2-mediated pathways.


CONCLUSIONS
Our findings suggest that the anti-inflammatory effects of DHEA in macrophages predominantly take place via inhibition of eicosanoids produced through COX-2.


BACKGROUND
This article is part of a themed section on Cannabinoids 2013 published in volume 171 issue 6. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.2014.171.issue-6/issuetoc.
Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
Jocelijn
J
Meijerink
Mieke
M
Poland
Michiel G J
MG
Balvers
Pierluigi
P
Plastina
Carolien
C
Lute
Jvalini
J
Dwarkasing
Klaske
K
van Norren
Renger F
RF
Witkamp
D000813:Anilides / Q000494:pharmacology; D000818:Animals; D001095:Arachidonic Acids / Q000494:pharmacology; D001892:Camphanes / Q000494:pharmacology; D002460:Cell Line; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology*; D003687:Dehydroepiandrosterone / Q000494:pharmacology*; D015232:Dinoprostone / Q000378:metabolism; D063388:Endocannabinoids / Q000378:metabolism; D007192:Indenes / Q000494:pharmacology; D016899:Interferon-beta / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D047495:PPAR gamma / Q000037:antagonists & inhibitors / Q000378:metabolism; D010880:Piperidines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D043885:Receptor, Cannabinoid, CB2 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000077285:Rimonabant; D000077154:Rosiglitazone; D045162:Thiazolidinediones / Q000494:pharmacology; D051196:Toll-Like Receptor 3 / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000378:metabolism
C457499:2-chloro-5-nitrobenzanilide; D000813:Anilides; D001095:Arachidonic Acids; D001892:Camphanes; D052246:Cyclooxygenase 2 Inhibitors; D063388:Endocannabinoids; D007192:Indenes; D008070:Lipopolysaccharides; C507780:Myd88 protein, mouse; D053594:Myeloid Differentiation Factor 88; C553580:N-(piperidin-1-yl)-1-(2,4-dichlorophenyl)-1,4-dihydro-6-methylindeno(1,2-c)pyrazole-3-carboxamide; D016328:NF-kappa B; D047495:PPAR gamma; D010880:Piperidines; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D043885:Receptor, Cannabinoid, CB2; C110630:SR 144528; C519703:TLR3 protein, mouse; D045162:Thiazolidinediones; C493487:Tlr4 protein, mouse; D051196:Toll-Like Receptor 3; D051197:Toll-Like Receptor 4; C119325:arachidonyl-2-chloroethylamide; D000077154:Rosiglitazone; D009569:Nitric Oxide; D003687:Dehydroepiandrosterone; D016899:Interferon-beta; C077623:Ptgs2 protein, mouse; D051546:Cyclooxygenase 2; D015232:Dinoprostone; D000077285:Rimonabant