Biosynthesis of the Novel Endogenous 15-Lipoxygenase Metabolites N-13-Hydroxy-octodecadienoyl-ethanolamine and 13-Hydroxy-octodecadienoyl-glycerol by Human Neutrophils and Eosinophils

Abstract

The endocannabinoids 2-arachidonoyl-glycerol and N-arachidonoyl-ethanolamine are lipids regulating many physiological processes, notably inflammation. Endocannabinoid hydrolysis inhibitors are now being investigated as potential anti-inflammatory agents. In addition to 2-arachidonoyl-glycerol and N-arachidonoyl-ethanolamine, the endocannabinoidome also includes other monoacylglycerols and N-acyl-ethanolamines such as 1-linoleoyl-glycerol (1-LG) and N-linoleoyl-ethanolamine (LEA). By increasing monoacylglycerols and/or N-acyl-ethanolamine levels, endocannabinoid hydrolysis inhibitors will likely increase the levels of their metabolites. Herein, we investigated whether 1-LG and LEA were substrates for the 15-lipoxygenase pathway, given that both possess a 1Z,4Z-pentadiene motif, near their omega end. We thus assessed how human eosinophils and neutrophils biosynthesized the 15-lipoxygenase metabolites of 1-LG and LEA. Linoleic acid (LA), a well-documented substrate of 15-lipoxygenases, was used as positive control. N-13-hydroxy-octodecadienoyl-ethanolamine (13-HODE-EA) and 13-hydroxy-octodecadienoyl-glycerol (13-HODE-G), the 15-lipoxygenase metabolites of LEA and 1-LG, were synthesized using Novozym 435 and soybean lipoxygenase. Eosinophils, which express the 15-lipoxygenase-1, metabolized LA, 1-LG, and LEA into their 13-hydroxy derivatives. This was almost complete after five minutes. Substrate preference of eosinophils was LA > LEA > 1-LG in presence of 13-HODE-G hydrolysis with methyl-arachidonoyl-fluorophosphonate. Human neutrophils also metabolized LA, 1-LG, and LEA into their 13-hydroxy derivatives. This was maximal after 15–30 s. Substrate preference was LA ≫ 1-LG > LEA. Importantly, 13-HODE-G was found in humans and mouse tissue samples. In conclusion, our data show that human eosinophils and neutrophils metabolize 1-LG and LEA into the novel endogenous 15-lipoxygenase metabolites 13-HODE-G and 13-HODE-EA. The full biological importance of 13-HODE-G and 13-HODE-EA remains to be explored.

Dysregulation of Bile Acids, Lipids, and Nucleotides in Psoriatic Arthritis Revealed by Unbiased Profiling of Serum Metabolites

“…Levels of cysteinyl‐glycine, guanine, and linoleoyl‐linoleoyl glycerol significantly decreased (>50%; P < 0.001) after the onset of PsA (Figures 6A and B). Linoleoyl glycerol is an endocannabinoid that is transformed by neutrophils and eosinophils to novel lipoxygenase metabolites (21), and cysteinyl‐glycine is a dipeptide intermediate in glutathione metabolism (22). In contrast, multiple inflammatory lipid metabolites (4‐hydroxydocosahexaenoic acid [4‐HDoHE], 12‐hydroxyeicosatetraenoic acid [12‐HETE], 12‐HHTrE) were elevated (>2‐fold; P < 0.01) in the PsP‐A patients.…”

Exploring the endocannabinoidome in genetically obese (ob/ob) and diabetic (db/db) mice: Links with inflammation and gut microbiota

“…We identified the presence of a possible inflammation-related molecular profile, since some of the observed alterations were characteristic of all tissues showing the most pronounced inflammatory response, i.e. : 1) 2-LG and its 12-lipoxygenase metabolite 13-HODE-G [30] were present in reduced concentrations, and 2) Trpv2 showed increased expression, in both the liver of ob/ ob mice and the adipose tissue depots of db/db mice. While still little is known about the receptors of 13-HODE-G, the levels of the established targets for 2-LG, i.e.…”

“…Conversely, we observed a statistically significant decrease of the 2-acylglycerol derivative (i.e., 2-LG) and the ethanolamine derivative (i.e., LEA) of linoleic acid (LA), in ob/ob mice with respect to db/db mice. 13-HODE-G, which is a novel endogenous molecule derived from the 12-lipoxygenase-catalysed oxygenation of 2-LG [30], displayed also significantly lower levels in ob/ob compared to db/db mice. The levels of the omega-3 fatty acid, eicosapentaenoic acid (EPA), and its derivative 2-EPG were also decreased in ob/ob mice with respect to the diabetic group, although the latter difference did not reach statistical significance (P = 0.072).…”

Marine Natural and Nature-Inspired Compounds Targeting Peroxisome Proliferator Activated Receptors (PPARs)

“…These PUFAs are ligands of all the three PPAR isoforms in the micromolar range [ 6 , 52 ]. Moreover, linoleate and arachidonate can be oxidated to 13-HODE and 15-HETE [ 53 ], respectively, globally functioning as dual PPARα/γ agonists, since 15-HETE is a PPARγ ligand, while 13-HODE is a dual PPARα/γ agonist [ 53 , 54 ]. Other PPARα/γ dual agonists have been identified with a bioassay-guided screening of organic extracts from the Norwegian Biobank of Arctic Marine Organisms.…”