Valeur pronostique des microparticules et de la balance coagulolytique au cours des états septiques graves

Le rôle des microparticules (MP) dans la pathogénèse du sepsis n'est pas complètement élucidé. Leur implication, en tant que bioeffecteurs paracrines dans l'inflammation, e stress oxydatif et les mécanismes de coagulation a été mise en évidence. Leur effet procoagulant est bien documenté et elles sont incriminées dans l'évolution vers la coagulation intravasculaire disséminée. En effet, elles offrent une surface catalytique permettant l'assemblage des facteurs de coagulation et la génération de thrombine. A contrario, leur activité profibrinolytique et ses conséquences cliniques demeurent méconnues. Notre étude a pour objet d'évaluer l'impact de la balance coagulolytique microparticulaire, sur la mortalité, les troubles de la perfusion tissulaire et les défaillances d'organe observées dans le choc septique. Trente-sept patients en sepsis sévère ou choc septique ont été inclus. Les données clinico-biologiques, les scores de morbimortalité et les défaillances d'organe ont été recueillies à J1 et J2. A ces dates, la balance coagulolytique a été évaluée sur l'activité microparticulaire du facteur tissulaire et de la plasmine. Elles sont appréciées par un test original de capture des MP pour un par text fonctionnel, et corrélées au dosage Plasminogen Activator Inhibitor de type 1 plasmatique (PAI-1) [ ]AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocSudocFranceF

Evaluation de l'activité ADAMTS 13 et des anticorps anti-ADAMTS au décours de la transplantation hépatique

AIX-MARSEILLE2-BU Méd/Odontol. (130552103) / SudocSudocFranceF

Two-Dimensional-Strain Echocardiography in Intensive Care Unit Patients: ă A Prospective, Observational Study

International audiencePurpose. Two-dimensional-strain echocardiography (2D-strain) is a ă promising technique for the early detection of myocardial dysfunction. ă Our study was aimed to assess its feasibility in the intensive care unit ă (ICU). Our secondary goal was to determine if 2D-strain could predict ă the patient's outcome. ă Methods. Conventional echocardiography and 2D-strain were performed on ă 64 consecutive patients admitted to our ICU. Using 2D-strain, the ă longitudinal deformation of the left ventricle was assessed. Feasibility ă of 2D-strain, diagnosis performance, and 28-day mortality prediction ă were determined. ă Results. 2D-strain measurements could be performed in 77% of our ă patients. All 2D-strain variables related to ventricular performance ă were significantly impaired in the patients who died compared with those ă who survived. Strain global medium was the only independent ă echocardiographic variable predictor of 28-day mortality rate (odds ă ratio 0.60; 95% confidence interval 0.43-0.80, p = 0.002). ă Conclusions. 2D-strain measurement is feasible in ICU patients, enabling ă identifying early left ventricle dysfunction. Strain global medium is an ă independent predictor of 28-day mortality. (C) 2016 Wiley Periodicals, ă Inc

A new assay to evaluate microvesicle plasmin generation capacity: validation in disease with fibrinolysis imbalance

International audienceAmong extracellular vesicles, leukocyte-derived microvesicles (LMVs) have emerged as complex vesicular structures. Primarily identified as procoagulant entities, they were more recently ascribed to plasmin generation capacity (MV-PGC). The objectives of this work were (1) to develop a new hybrid bio-assay combining the specific isolation of LMVs and measurement of their PGC, and compare its performance to the original method based on centrifugation, (2) to validate MV-PGC in septic shock, combining increased levels of LMVs and fibrinolytic imbalance. Using plasma sample spiked with LMVs featuring different levels of PGC, we demonstrated that CD15-beads specifically extracted LMVs. The MV dependency of the test was demonstrated using electron microscopy, high speed centrifugation, nanofiltration and detergent-mediated solubilization and the MV-PGC specificity using plasmin-specific inhibitors, or antibodies blocking elastase or uPA. Thanks to a reaction booster (epsilon-ACA), we showed that the assay was more sensitive and reproducible than the original method. Moreover, it exhibited a good repeatability, inter-operator and inter-experiment reproducibility. The new immunomagnetic bio-assay was further validated in patients with septic shock. As a result, we showed that MV-PGC values were significantly lower in septic shock patients who died compared to patients who survived, both at inclusion and 24 h later (1.4 [0.8-3.0] vs 3.1 [1.7-18] A(405) x 10(-3)/min, p = 0.02; 1.4 [1-1.6] vs 5.2 [2.2-16] A(405) x 10(-3)/min, p = 0.004). Interestingly, combining both MV-PGC and PAI-1 in a ratio significantly improved the predictive value of PAI-1. This strategy, a hybrid capture bioassay to specifically measure LMV-PGC using for the first time, opens new perspectives for measuring subcellular fibrinolytic potential in clinical settings with fibrinolytic imbalance

Granulocyte microvesicles with a high plasmin generation capacity promote clot lysis and improve outcome in septic shock

International audienceAbstract Microvesicles (MVs) have previously been shown to exert profibrinolytic capacity, which is increased in patients with septic shock (SS) with a favorable outcome. We, therefore, hypothesized that the plasmin generation capacity (PGC) could confer to MVs a protective effect supported by their capacity to lyse a thrombus, and we investigated the mechanisms involved. Using an MV-PGC kinetic assay, ELISA, and flow cytometry, we found that granulocyte MVs (Gran-MVs) from SS patients display a heterogeneous PGC profile driven by the uPA (urokinase)/uPAR system. In vitro, these MVs lyse a thrombus according to their MV-PGC levels in a uPA/uPAR-dependent manner, as shown in a fluorescent clot lysis test and a lysis front retraction assay. Fibrinolytic activators conveyed by MVs contribute to approximately 30% of the plasma plasminogenolytic capacity of SS patients. In a murine model of SS, the injection of high PGC Gran-MVs significantly improved mouse survival and reduced the number of thrombi in vital organs. This was associated with a modification of the mouse coagulation and fibrinolysis properties toward a more fibrinolytic profile. Interestingly, mouse survival was not improved when soluble uPA was injected. Finally, using a multiplex array on plasma from SS patients, we found that neutrophil elastase correlates with the effect of high-PGC-capacity plasma and modulates the Gran-MV plasmin generation capacity by cleaving uPA-PAI-1 complexes. In conclusion, we show that the high PGC level displayed by Gran-MVs reduces thrombus formation and improves survival, conferring to Gran-MVs a protective role in a murine model of sepsis