Comparison of eight 15-lipoxygenase (LO) inhibitors on the biosynthesis of 15-LO metabolites by human neutrophils and eosinophils

PLoS One. 2018 Aug 17;13(8):e0202424. doi: 10.1371/journal.pone.0202424. eCollection 2018.

Abstract

Neutrophils and eosinophils are important sources of bioactive lipids from the 5- and the 15-lipoxygenase (LO) pathways. Herein, we compared the effectiveness of humans eosinophils and eosinophil-depleted neutrophils to synthesize 15-LO metabolites using a cocktail of different 15-LO substrates as well as their sensitivities to eight documented 15-lipoxygenase inhibitors. The treatment of neutrophils and eosinophils with linoleic acid, dihomo-γ-linolenic acid, arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid and arachidonyl-ethanolamide, led to the synthesis of 13-HODE, 15-HETrE, 15-HETE, 15-HEPE, 14-HDHA/17-HDHA, and 15-hydroxy-AEA. Neutrophils and eosinophils also metabolized the endocannabinoid 2-arachidonoyl-glycerol into 15-HETE-glycerol, although this required 2-arachidonoyl-glycerol hydrolysis inhibition. Neutrophils and eosinophils differed in regard to dihomo-γ-linolenic acid and linoleic acid utilization with 15-HETrE/13-HODE ratios of 0.014 ± 0.0008 and 0.474 ± 0.114 for neutrophils and eosinophils respectively. 15-LO metabolite synthesis by neutrophils and eosinophils also differed in regard to their relative production of 17-HDHA and 14-HDHA.The synthesis of 15-LO metabolites by neutrophils was concentration-dependent and rapid, reaching a plateau after one minute. While investigating the biosynthetic routes involved, we found that eosinophil-depleted neutrophils express the 15-lipoxygenase-2 but not the 15-LO-1, in contrast to eosinophils which express the 15-LO-1 but not the 15-LO-2. Moreover, 15-LO metabolite synthesis by neutrophils was not inhibited by the 15-LO-1 inhibitors BLX769, BLX3887, and ML351. However, 15-LO product synthesis was partially inhibited by 100 μM NDGA. Altogether, our data indicate that the best 15-LO-1 inhibitors in eosinophils are BLX3887, BLX769, NDGA and ML351 and that the synthesis of 15-LO metabolites by neutrophils does not involve the 15-LO-1 nor the phosphorylation of 5-LO on Ser-663 but is rather the consequence of 15-LO-2 or another unidentified 15-LO.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arachidonate 15-Lipoxygenase / metabolism*
  • Dose-Response Relationship, Drug
  • Eicosapentaenoic Acid / analogs & derivatives*
  • Eicosapentaenoic Acid / metabolism*
  • Eosinophils / metabolism*
  • Female
  • Humans
  • Lipoxygenase Inhibitors / pharmacology*
  • Male
  • Neutrophils / metabolism*
  • Time Factors

Substances

  • Lipoxygenase Inhibitors
  • Eicosapentaenoic Acid
  • Arachidonate 15-Lipoxygenase

Grant support

This work was supported by grants to NF from the Natural Sciences and Engineering Research Council of Canada, and the Respiratory Health Network of the Fonds de recherche du Québec-Santé. CL, JC, EB, ML, YB and NF are members of the inflammation group of the Respiratory Health Network of the Fonds de recherche du Québec-Santé. CT and MCL are the recipients of a doctoral award from the Canadian Institutes of Health Research. ASA is the recipient of a doctoral award from the Fonds de Recherche du Québec-Santé. CL is chair holder of the Canada Research Chair in the Environment and Genetics of Respiratory Disorders and Allergies. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.