Ageing enhances the shedding of splenocyte microvesicles with endothelial pro-senescent effect that is prevented by a short-term intake of omega-3 PUFA EPA:DHA 6:1

Abstract

BackgroundAgeing is associated with progressive endothelial senescence and dysfunction, and cardiovascular risk. Circulating endothelial microvesicles (MVs) are pro-senescent and pro-inflammatory endothelial effectors in acute coronary syndrome. Omega-3 PUFA intake was claimed beneficial in cardiovascular prevention. PurposeTo investigate whether the intake of the omega-3 formulation EPA:DHA 6:1 by middle-aged and old rats reduces the shedding of pro-senescent microvesicles from cultured spleen leukocytes (SMVs) and clarify the underlying mechanisms in target coronary primary endothelial cells (ECs). MethodsMiddle-aged male Wistar rats (M, 48-week old) received 500 mg/kg/d of either EPA:DHA 6:1, EPA:DHA 1:1, or vehicle (CTL) for 7 days, old rats (72-week old) for 14 days. Spleen-derived leukocytes were prepared and cultured for 24 h and MVs collected from supernatants (SMVs). Cultured ECs were prepared from freshly isolated porcine coronary arteries. Senescence-associated β-galactosidase activity (SA-β-gal) was assessed by C12FDG, protein expression by Western blot analysis, oxidative stress by dihydroethidium using confocal microscopy, and procoagulant MVs by prothrombinase assay. The pro-senescent potential of SMVs from middle-aged rats (M−SMVs) was analyzed by comparison with young (Y, 12-week) and old (O) rats. ResultsThe shedding of SMVs significantly increased with age and was inhibited by EPA:DHA 6:1 intake that also prevented ROS accumulation in spleen. Incubation of ECs with 10 nM SMVs from middle-aged and old but not those from young rats induced premature senescence after 48 h. The pro-senescent effect of M−SMVs was prevented by Losartan and associated with endothelial oxidative stress. M−SMVs induced an up-regulation of senescence markers (p16, p21, p53), pro-atherothrombotic (VCAM-1, ICAM-1, tissue factor) and pro-inflammatory markers (pNF-κB, COX-2) and proteins of the angiotensin system (ACE, AT1-R). Conversely, endothelial NO synthase was down-regulated. Intake of EPA:DHA 1:1 and 6:1 by middle-aged rats decreased SMV shedding by 14% and 24%, respectively. Only EPA:DHA 6:1 intake abolished the M−SMVs−induced endothelial senescence and reduced the pro-senescent action of O-SMVs by 45%. Protection of ECs was not observed in response to SMVs from EPA:DHA 1:1 treated rats. ConclusionIngestion of EPA:DHA 6:1 by middle-aged or old rats, respectively abolished or limited both the shedding of SMVs and their pro-senescent, pro-thrombotic and pro-inflammatory effects in ECs, most likely by triggering the local angiotensin system. EPA:DHA 6:1 may help to delay ageing-related endothelial dysfunction.