Les microparticules circulantes : un nouvel acteur dans le sepsis ?

During sepsis, inflammation and thrombosis can be both orchestrated by the interactions between circulating cells, such as leukocytes and platelets with endothelial and smooth muscle cells, which, during activation or apoptosis, can release circulating microparticles (MP). Microparticles are a disseminated storage pool of bioeffectors, circulating ubiquitous, involved in healthy individuals and in several diseases and they take part in vascular function, strengthening the notion that they may play a role in both organ functions and dysfunctions. Indeed, MP have been identified as vectors of the intercellular exchange of biologic information, such induction of vascular dysfunction. Indeed, microparticles are membrane vesicles with procoagulant and pro-inflammatory properties which are present during sepsis, and strengthening the concept that they may play a role in this syndrome. Circulating microparticles display deleterious effects on endothelial and/or vasomotor function. Indeed, they induce NO release dysfunction and increase production of reactive oxygen species. Phosphatidylserine, one of the specificity of microparticles is considered as a starter of coagulation cascade. Furthermore, microparticles can provide tissular factor, the initial activator of the blood coagulation pathway that ultimately lead to the generation of a fibrin clot and disseminated coagulopathy during sepsis. Procoagulant and pro-inflammatory properties of microparticles could participate to hemodynamic and multiorgan failures that feature septic shock.