Circulating microparticles released during dyslipidemia may exert deleterious effects on blood vessels and endothelial function.

AIMS: To compare the bioactivity of circulating microparticles (MPs) isolated from dyslipidemic Psammomys obesus (P. obesus) fed a high-energy diet (HED) with those released from healthy P. obesus fed a normal diet (ND). METHODS: Vascular reactivity of aortic rings was evaluated by myography, after 24 h incubation in the absence or in the presence of circulating MPs isolated, by differential centrifugations, from the plasma of animals subjected to HED (MPsHED) or ND (MPsND) for 12 weeks. Human umbilical vein endothelial cells (HUVECs) were treated for 24 h with MPsHED or MPsND animals and subjected to immunofluorescence staining of caveolin-1 (cav-1), intercellular adhesion molecule-1 (ICAM-1), endothelial nitric oxide synthase (eNOS), F-actin and reactive oxygen species (ROS) detection. RESULTS: The HED exerted a distinctly pronounced hyperlipidemic effect marked by plasmatic increase of total cholesterol, low-density lipoprotein-cholesterol (LDL-C) and triglyceride (TG). Both MPsND and MPsHED induced a significant reduction of maximal relaxation induced by acetylcholine (ACh). Interestingly, MPsHED significantly decreased eNOS expression up to ~25% and increased ROS production up to ~75% on in vitro treated HUVECs. Moreover, in HUVECs, MPsHED significantly decreased cav-1 expression up to ~50% whereas significant increase of ICAM-1 expression by about 2-fold approximately was observed. CONCLUSION: Our experimental study demonstrated the dual role of MPs on vascular function by modulating endothelial cell function. Furthermore, MPs may be considered as vectors of a bioactive information contributing to inflammation and vascular damage.