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.

BACKGROUND: Ageing 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. PURPOSE: To 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). METHODS: Middle-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 ß-galactosidase activity (SA-ß-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. RESULTS: The 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. CONCLUSION: Ingestion 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.

Studies of circulating microparticle release in peripheral blood after pancreatic islet transplantation.

The loss of graft function after intraportal islet transplantation is likely multifactorial involving allogeneic rejection, recurrent autoimmunity, graft exhaustion due to a marginally implanted islet mass, immunosuppressant toxicity, and impaired ß-cell regeneration. Because early markers of the loss of ß-cell mass or function are lacking, monitoring of islet function remains a challenging issue. We have reported herein monitoring of membrane procoagulant microparticles (MPs) as markers of cell stress in the plasma of three recipients with various clinical histories. Early kinetics of C-peptide and MPs followed identical patterns during the first weeks after transplantation; a major increase probably reflected processes related to cell infusion and islet engraftment. Importantly in the case of rejection, MPs and C-peptide showed opposite patterns. A fall in C-peptide was associated with enhanced insulin needs. Our results suggested that a peak in MP levels might indicate rejection with prognotic value. Treatment of the loss of islet function by a new islet infusion or steroid therapy returned MP and C-peptide levels to their baselines with concomitant restoration of islet function. In the patient with suspected acute cellular rejection, MPs also appeared to be sensors of immunosuppressive steroid therapy.

Evidence for heterogeneity of the obstetric antiphospholipid syndrome: thrombosis can be critical for antiphospholipid-induced pregnancy loss.

BACKGROUND: Antiphospholipid antibodies are associated with thrombosis and repeated pregnancy losses during the antiphospholipid syndrome. Several experimental findings indicate that purified antiphospholipid antibodies are directly responsible for inflammation-induced pregnancy losses, or for disruption of the annexin A5 shield at the trophoblastic interface. We previously showed that passive transfer of CIC15, a monoclonal antiphospholipid antibody binding to cardiolipin and annexin A5 that was isolated from a patient with primary antiphospholipid syndrome, induces fetal resorption in pregnant mice. OBJECTIVES: To investigate the mechanisms of CIC15-induced pregnancy loss. METHODS/RESULTS: We show that CIC15 induces fetal loss through a new mechanism that is probably related to procoagulant activity. The time course is different from those of previously described models, and histologic analysis shows that the placentas are devoid of any sign of inflammation but display some signs of thrombotic events. Despite these differences, the CIC15 and 'inflammatory' models share some similarities: lack of FcγRI/III dependency, and the efficacy of heparin in preventing fetal losses. However, this latter observation is here mostly attributable to anticoagulation rather than complement inhibition, because fondaparinux sodium and hirudin show similar efficiency. In vitro, CIC15 enhances cardiolipin-induced thrombin generation. Finally, using a combination of surface-sensitive methods, we show that, although it binds complexes of cardiolipin-annexin A5, CIC15 is not able to disrupt the two-dimensional ordered arrays of annexin A5. CONCLUSIONS: This human monoclonal antibody is responsible for pregnancy loss through a new mechanism involving thrombosis. This mechanism adds to the heterogeneity of the obstetric antiphospholipid syndrome.

[Procoagulant membranous microparticles and atherothrombotic complications in diabetics]. / Microparticules membranaires procoagulantes et complications athérothrombotiques chez le patient diabétique.

Endothelial apoptosis and platelet activation play a key role in atherothrombotic event. These two mechanisms resulting membrane thickening leading to procoagulant microparticle (MP) liberation into the blood stream. In the vascular compartment, MP contribute to increased thrombin formation, to platelet activation, and prolong inflammation of the arterial wall by inducing the synthesis of cytokines and adhesion of glycoproteins by the endothelial cells. In diabetic patients, increased endothelial apoptosis associated with intense platelet and monocytic activation could contribute to accelerated atherothrombosis. Endothelial, platelet and monocytic derived MP, found in high concentrations in these patients, induce a prothrombotic, proadhesive and proinflammatory tendency in the vascular comportment which could directly impact on the vascular prognosis. In diabetes, increased platelet or monocytic MP is a marker for microvascular disease. Likewise, in acute coronary syndromes of diabetic patients, high concentrations of procoagulant MP could be associated with a poor cardiovascular prognosis. In these diabetic patients, many treatments (antioxidant, antiplatelet, lipid lowering, antihypertensive) significantly reduce the levels of MP and parameters associated with inflammation. MP are one of the key factors linking inflammation, oxidative stress, apoptosis and thrombosis in accelerated atherothrombotic disease of the diabetic. In future, the measurement of MP should help evaluate the efficacy of antioxidant and antiplatelet therapy, especially in diabetic patients.