The Antithrombotic Effects of 12‐LOX Derived Metabolites of DPA, ω‐6

Abstract

IntroductionPlatelet‐mediated thrombosis is the primary underlying mechanism leading to cardiovascular life‐threatening clinical events. Regulating excessive platelet reactivity is an essential aspect of antithrombotic therapy. A number of anti‐platelet drugs have been developed to target specific signaling pathways or endpoints involved in platelet activation. Despite the effectiveness of current anti‐platelet therapies, uncontrolled thrombosis or bleeding complications still persist, warranting the development of novel anti‐thrombotic strategies. Previously, we had presented that 12‐HETrE, an oxylipin generated by 12‐lipoxygenase (12‐LOX) oxidation of ω‐6 polyunsaturated fatty acid (PUFA), dihomo‐g‐linolenic acid (DGLA), could be an approach to modulate platelet reactivity through the prostacyclin receptor. Here, we demonstrate that the elongated form of DGLA, docosapentaenoic acid (DPA; 22:5n‐6) can also be endogenously oxidized by platelet 12‐LOX to generate two distinct oxylipins, 11‐oxy‐DPA and 14‐oxy‐DPA, to regulate platelet reactivity.ObjectiveTo determine the efficacy of and the mechanistic target of 12‐LOX derived metabolites of DPA 11‐ and 14‐oxy‐DPA, ω‐6 in the regulation of platelet function.ResultsBoth 11‐ and 14‐oxy‐DPA potently inhibited platelet aggregation in an aggregometer measuring optical density. Treatment of whole blood with 11‐ and 14‐oxy‐DPA, ω‐6 also significantly reduced platelet adhesion as well as thrombus growth on an ex vivo collagen‐coated perfusion chamber under arterial shear. In support of these findings, using flow cytometry, calcium mobilization was attenuated in platelets treated with 11‐ and 14‐oxy‐DPA, ω‐6. Interestingly, both 11‐ and 14‐oxy‐DPA inhibited platelet activation in a Gas independent manner. Instead, 11‐oxy‐DPA and 14‐oxy‐DPA exerted their anti‐platelet effects through a peroxisome proliferated‐activated receptor (PPAR), by which pharmacological antagonism of the PPARα isoform reversed the ability of the metabolites to inhibit platelet aggregation. In supplement of these ex vivo findings, ongoing experiments are being performed to measure laser‐induced thrombus formation (platelet and fibrin) in the cremaster vessel of wild‐type mice intravenously administered with either 11‐ and 14‐oxy‐DPA.ConclusionThis is the first study to demonstrate the novel metabolites of DPA, ω‐6 generated by 12‐LOX also have a role in regulating platelet activation through the PPAR pathway. Our findings suggest that 11‐ and 14‐oxy‐DPA, ω‐6 shows great promise as a potential anti‐platelet therapeutic for the treatment for cardiovascular‐related diseases.Support or Funding InformationThis work was funded in part through the National Institutes of Health grants R01 GM105671 (MH), R01 HL114405 (MH), R01 MD007880 (MH).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.