Defining the role of 12-lipoxygenase in regulating platelet-derived extracellular vesicles.

Platelets are traditionally recognized for their role in hemostasis and wound repair, yet they also play a pivotal role in intercellular communication through the release of platelet-derived extracellular vesicles (PMVs). These vesicles contribute to diverse physiological and pathological processes, but the mechanisms governing their biogenesis remain incompletely understood. One candidate regulator is 12-lipoxygenase (12-LO), an enzyme that metabolizes arachidonic acid into the lipid mediator 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE). While 12-LO has been linked to coagulation and neutrophil interactions, its involvement in PMV production has not been clearly defined. In this study, we investigated the role of 12-LO in PMV biogenesis using both human and murine platelet models. Pharmacological inhibition of 12-LO significantly reduced 12(S)-HETE levels and PMV release in activated human platelets. Similarly, platelets from 12-LO-deficient (Alox12-/-) mice exhibited markedly impaired PMV production upon stimulation. Subpopulation analyses revealed agonist-specific effects of 12-LO deficiency on distinct PMV subsets, including mitochondrial-containing vesicles. Importantly, supplementation with exogenous 12(S)-HETE partially restored PMV production in Alox12-/- platelets, confirming the functional relevance of this lipid mediator. Together, these findings identify 12-LO as a critical regulator of PMV biogenesis and suggest that the 12-LO/12(S)-HETE axis represents a novel therapeutic target in inflammatory and thrombotic disorders.