Differential Effect of Omega-3 Fatty Acids on Platelet Inhibition by Antiplatelet Drugs In Vitro

The omega-3 polyunsaturated fatty acids (PUFAs) Docosahexaenoic acid (DHA) and Eicosapentaenoic acid (EPA) exert multiple cardioprotective effects, influencing inflammation, platelet activation, endothelial function and lipid metabolism, besides their well-established triglyceride lowering properties. It is not uncommon for omega-3 PUFAs to be prescribed for hypertriglyceridemia, alongside antiplatelet therapy in cardiovascular disease (CVD) patients. In this regard, we studied the effect of EPA and DHA, in combination with antiplatelet drugs, in platelet aggregation and P-selectin and α_IIbβ₃ membrane expression. The antiplatelet drugs aspirin and triflusal, inhibitors of cyclooxygenase-1 (COX-1); ticagrelor, an inhibitor of the receptor P2Y₁₂; vorapaxar, an inhibitor of the PAR-1 receptor, were combined with DHA or EPA and evaluated against in vitro platelet aggregation induced by agonists arachidonic acid (AA), adenosine diphosphate (ADP) and TRAP-6. We further investigated procaspase-activating compound 1 (PAC-1) binding and P-selectin membrane expression in platelets stimulated with ADP and TRAP-6. Both DHA and EPA displayed a dose-dependent inhibitory effect on platelet aggregation induced by AA, ADP and TRAP-6. In platelet aggregation induced by AA, DHA significantly improved acetylsalicylic acid (ASA) and triflusal's inhibitory activity, while EPA enhanced the inhibitory effect of ASA. In combination with EPA, ASA and ticagrelor expressed an increased inhibitory effect towards ADP-induced platelet activation. Both fatty acids could not improve the inhibitory effect of vorapaxar on AA- and ADP-induced platelet aggregation. In the presence of EPA, all antiplatelet drugs displayed a stronger inhibitory effect towards TRAP-6-induced platelet activation. Both omega-3 PUFAs inhibited the membrane expression of α_IIbβ₃, though they had no effect on P-selectin expression induced by ADP or TRAP-6. The antiplatelet drugs exhibited heterogeneity regarding their effect on P-selectin and α_IIbβ₃ membrane expression, while both omega-3 PUFAs inhibited the membrane expression of α_IIbβ₃, though had no effect on P-selectin expression induced by ADP or TRAP-6. The combinatory effect of DHA and EPA with the antiplatelet drugs did not result in enhanced inhibitory activity compared to the sum of the individual effects of each component.