DHA 12-LOX-derived oxylipins regulate platelet activation and thrombus formation through a PKA-dependent signaling pathway.

The effects of the docosahexaenoic acid (DHA) on cardiovascular disease are controversial and a mechanistic understanding of how this ω-3 polyunsaturated fatty (ω-3 PUFA) regulates platelet reactivity and the subsequent risk of a thrombotic event is warranted. In platelets, DHA is oxidized by 12-lipoxygenase (12-LOX) producing the oxidized lipids (oxylipins) 11-HDHA and 14-HDHA. We hypothesized that 12-LOX DHA-oxylipins may be involved in the beneficial effects observed in dietary supplemental treatment with ω-3 PUFAs or DHA itself. To determine the effects of DHA, 11-HDHA and 14-HDHA on platelet function and thrombus formation, and to elucidate the mechanism by which these ω-3 PUFAs regulate platelet activation. DHA, 11-HDHA and 14-HDHA attenuated collagen-induced human platelet aggregation, but only the oxylipins inhibited αIIbβ3 activation and decreased α-granule secretion. Furthermore, treatment of whole blood with DHA and its oxylipins impaired platelet adhesion and accumulation to a collagen-coated surface. Interestingly, thrombus formation was only diminished in mice treated with 11-HDHA or 14-HDHA, and mouse platelet activation was inhibited following acute treatment with these oxylipins or chronic treatment with DHA, suggesting that under physiologic conditions, the effects of DHA are mediated through its oxylipins. Finally, the protective mechanism of DHA oxylipins was shown to be mediated via activation of protein kinase A. This study provides the first mechanistic evidence of how DHA and its 12-LOX oxylipins inhibit platelet activity and thrombus formation. These findings support the beneficial effects of DHA as therapeutic intervention in atherothrombotic diseases.

二十二碳六烯酸（DHA）对心血管疾病的影响存在争议，因此有必要从机制上理解这种ω - 3多不饱和脂肪酸（ω - 3 PUFA）是如何调节血小板反应性以及随后的血栓形成风险的。在血小板中，DHA被12 - 脂氧合酶（12 - LOX）氧化，产生氧化脂质（氧脂素）11 - HDHA和14 - HDHA。我们假设12 - LOX DHA - 氧脂素可能参与了在膳食补充ω - 3 PUFA或DHA本身治疗中所观察到的有益效果。 为了确定DHA、11 - HDHA和14 - HDHA对血小板功能和血栓形成的影响，并阐明这些ω - 3 PUFA调节血小板活化的机制。 DHA、11 - HDHA和14 - HDHA减弱了胶原蛋白诱导的人血小板聚集，但只有氧脂素抑制了αIIbβ3的活化并减少了α - 颗粒的分泌。此外，用DHA及其氧脂素处理全血会损害血小板在胶原蛋白包被表面的黏附和聚集。有趣的是，只有用11 - HDHA或14 - HDHA处理的小鼠血栓形成减少，并且在对这些氧脂素进行急性处理或对DHA进行慢性处理后，小鼠血小板活化受到抑制，这表明在生理条件下，DHA的作用是通过其氧脂素来介导的。最后，显示DHA氧脂素的保护机制是通过蛋白激酶A的激活来介导的。 这项研究首次从机制上证明了DHA及其12 - LOX氧脂素是如何抑制血小板活性和血栓形成的。这些发现支持了DHA作为动脉粥样硬化血栓性疾病的治疗干预措施的有益效果。