12-HETrE inhibits platelet reactivity and thrombosis in part through the prostacyclin receptor

Abstract

Key Points• The antiplatelet effects of 12-HETrE in humans and mice are partly dependent on IP in vitro.• The antithrombotic effects of 12-HETrE are partially dependent on IP in vivo in mice.The dihomo-g-linolenic acid (DGLA)-derived metabolite of 12-lipoxygenase, 12-hydroxyeicosatrienoic acid (12-HETrE), was recently shown to potently inhibit thrombus formation without prolonging bleeding in murine models. Although 12-HETrE was found to inhibit platelet activation via the Ga s signaling pathway, the Ga s -coupled receptor by which 12-HETrE mediates its antiplatelet effects has yet to be identified. Defining the receptor by which 12-HETrE exerts its effects is key to determining its therapeutic potential as an antiplatelet drug. Therefore, the goal of this study was to determine the Ga s -coupled platelet receptor through which 12-HETrE exerts its antiplatelet effects. In this study, we showed that pharmacological inhibition of the prostacyclin (IP) receptor in human platelets or genetic ablation of IP in murine platelets prevented 12-HETrE from blocking aggregation in vitro.Furthermore, the antithrombotic effects of 12-HETrE were significantly diminished in IP knockout mice in vivo. Together these data demonstrate that the antiplatelet effects of 12-HETrE are at least partially dependent on IP signaling. Importantly, this work identified 12-HETrE as a novel regulator of IP signaling that may aid in the rationale for design of novel therapeutics to inhibit platelet function. Additionally, this study provides further insight into the mechanism by which DGLA supplementation inhibits platelets function.

Platelet lipidome: Dismantling the “Trojan horse” in the bloodstream

“…12‐LOX catalyzes hydroperoxidation of PUFAs to generate 12‐HpETE (AA‐derived), and 12‐HpETrE (DGLA‐derived), which exert pro‐ and antithrombotic actions, respectively . 12‐HpETE is reduced to 12‐HETE by glutathione reductase and synergistically enhances aggregatory response to collagen, ADP, and PAR activation, but counteracts that of AA .…”

“…Dihomo‐γ‐linolenic acid derived 12‐HETrE acts on a Gsα coupled IP receptor, leads to activation of adenylyl cyclase, generation of cAMP, and PKA activity culminating in vasodilator‐stimulated phospho‐protein (VASP) phosphorylation, a well‐characterized platelet inhibitory track otherwise employed by endothelial PGI2. Therefore, DGLA or 12‐HETrE supplementation checks aggregation in vitro, and retards platelet accumulation at the injured cremaster arterioles and carotid artery in vivo . Platelet 12‐LOX simultaneously metabolizes AA and DGLA, but AA being more abundant, 12‐HETE generation exceeds that of 12‐HETrE.…”

“…However, the DGLA‐12‐HETrE antithrombotic axis operates independently of COX‐1, is not influenced by aspirin, and does not compromise primary hemostasis, making it a promising antiplatelet strategy . Limited amounts of DGLA in platelet membrane might be enhanced by dietary supplementation without altering levels of thrombogenic 12‐LOX (12‐HETE) or COX‐1 (TXA2) derivatives . It would be interesting to validate how antiplatelet therapies might influence the endogenous levels of antiplatelet lipids in CVD patients.…”

“…Therefore, DGLA or 12-HETrE supplementation checks aggregation in vitro, and retards platelet accumulation at the injured cremaster arterioles and carotid artery in vivo. 81,82 Platelet 12-LOX simultaneously metabolizes AA and DGLA, but AA being more abundant, 12-HETE generation exceeds that of 12-HETrE. Dihomo-γ-linolenic acid is also converted to PGD1 and PGE1 by COX-1 oxygenation, while AA generates PGI2.…”

“…However, the DGLA-12-HETrE antithrombotic axis operates independently of COX-1, is not influenced by aspirin, and does not compromise primary hemostasis, making it a promising antiplatelet strategy. 81,82 Limited amounts of DGLA in platelet membrane might be enhanced by dietary supplementation without altering levels of thrombogenic F I G U R E 3 Pro-(in red) and anti-thrombotic (in green) lipid derivatives of AA, DPA, DHA, EPA and DGLA generated in platelets through the enzymatic actions of COX-1 and 12-LOX. CYP450 derived metabolites have been shown in platelets; those from other cellular sources like endothelial cells mostly show antiplatelet properties 12-LOX (12-HETE) or COX-1 (TXA2) derivatives.…”