12(S)-HETrE, a 12-Lipoxygenase Oxylipin of Dihomo-γ-Linolenic Acid, Inhibits Thrombosis via Gαs Signaling in Platelets

Arterioscler Thromb Vasc Biol. 2016 Oct;36(10):2068-77. doi: 10.1161/ATVBAHA.116.308050. Epub 2016 Jul 28.

Abstract

Objective: Dietary supplementation with polyunsaturated fatty acids has been widely used for primary and secondary prevention of cardiovascular disease in individuals at risk; however, the cardioprotective benefits of polyunsaturated fatty acids remain controversial because of lack of mechanistic and in vivo evidence. We present direct evidence that an omega-6 polyunsaturated fatty acid, dihomo-γ-linolenic acid (DGLA), exhibits in vivo cardioprotection through 12-lipoxygenase (12-LOX) oxidation of DGLA to its reduced oxidized lipid form, 12(S)-hydroxy-8Z,10E,14Z-eicosatrienoic acid (12(S)-HETrE), inhibiting platelet activation and thrombosis.

Approach and results: DGLA inhibited ex vivo platelet aggregation and Rap1 activation in wild-type mice, but not in mice lacking 12-LOX expression (12-LOX(-/-)). Similarly, wild-type mice treated with DGLA were able to reduce thrombus growth (platelet and fibrin accumulation) after laser-induced injury of the arteriole of the cremaster muscle, but not 12-LOX(-/-) mice, supporting a 12-LOX requirement for mediating the inhibitory effects of DGLA on platelet-mediated thrombus formation. Platelet activation and thrombus formation were also suppressed when directly treated with 12(S)-HETrE. Importantly, 2 hemostatic models, tail bleeding and arteriole rupture of the cremaster muscle, showed no alteration in hemostasis after 12(S)-HETrE treatment. Finally, the mechanism for 12(S)-HETrE protection was shown to be mediated via a Gαs-linked G-protein-coupled receptor pathway in human platelets.

Conclusions: This study provides the direct evidence that an omega-6 polyunsaturated fatty acid, DGLA, inhibits injury-induced thrombosis through its 12-LOX oxylipin, 12(S)-HETrE, which strongly supports the potential cardioprotective benefits of DGLA supplementation through its regulation of platelet function. Furthermore, this is the first evidence of a 12-LOX oxylipin regulating platelet function in a Gs α subunit-linked G-protein-coupled receptor-dependent manner.

Keywords: blood platelets; eicosanoids; fibrin; lipoxygenase; platelet activation; thrombosis.

Publication types

  • Video-Audio Media

MeSH terms

  • 8,11,14-Eicosatrienoic Acid / analogs & derivatives*
  • 8,11,14-Eicosatrienoic Acid / metabolism
  • 8,11,14-Eicosatrienoic Acid / pharmacology*
  • Animals
  • Arachidonate 12-Lipoxygenase / blood*
  • Arachidonate 12-Lipoxygenase / deficiency
  • Arachidonate 12-Lipoxygenase / genetics
  • Blood Platelets / drug effects*
  • Blood Platelets / metabolism
  • Cell Adhesion Molecules / blood
  • Chromogranins / blood*
  • Cyclic AMP / blood
  • Cyclic AMP-Dependent Protein Kinases / blood
  • Disease Models, Animal
  • Fibrinolytic Agents / metabolism
  • Fibrinolytic Agents / pharmacology*
  • GTP-Binding Protein alpha Subunits, Gs / blood*
  • Humans
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Microfilament Proteins / blood
  • Oxidation-Reduction
  • Phosphoproteins / blood
  • Phosphorylation
  • Platelet Activation / drug effects*
  • Platelet Aggregation / drug effects
  • Platelet Aggregation Inhibitors / pharmacology*
  • Signal Transduction / drug effects
  • Telomere-Binding Proteins / blood
  • Thrombosis / blood
  • Thrombosis / enzymology
  • Thrombosis / genetics
  • Thrombosis / prevention & control*
  • Time Factors

Substances

  • 12-hydroxy-8,10,14-eicosatrienoic acid
  • Cell Adhesion Molecules
  • Chromogranins
  • Fibrinolytic Agents
  • Microfilament Proteins
  • Phosphoproteins
  • Platelet Aggregation Inhibitors
  • TERF2IP protein, mouse
  • Telomere-Binding Proteins
  • vasodilator-stimulated phosphoprotein
  • Cyclic AMP
  • Arachidonate 12-Lipoxygenase
  • ALOX12 protein, human
  • Cyclic AMP-Dependent Protein Kinases
  • GNAS protein, human
  • GTP-Binding Protein alpha Subunits, Gs
  • 8,11,14-Eicosatrienoic Acid