Characterization of Circulating Extracellular Vesicle Surface Antigens in Patients With Primary Aldosteronism

Primary aldosteronism (PA) is characterized by inappropriate aldosterone production. Chronic aldosterone excess has detrimental effects on cardiovascular system, including endothelial dysfunction and vascular inflammation. Circulating extracellular vesicles (EVs) are central players in the crosstalk between endothelium, vascular structures, and inflammatory cells. The aim of the study was to assess the potential role of EVs in aldosterone-related vascular damage by evaluating a comprehensive panel of 37 EV surface antigens. Serum EVs were isolated by immunocapture from 32 patients with PA, 29 patients with essential hypertension and from 22 normotensive controls. EVs were characterized by Western blotting, nanoparticle tracking analysis, transmission electron microscopy, and flow cytometry. Particle concentration was higher and diameter lower in patients with PA compared with controls and the number of particles decreased after unilateral adrenalectomy. Nineteen EV surface antigens were differentially expressed in patients with PA compared with patients with essential hypertension or normotensive controls, including markers of activated platelets, endothelial and immune/inflammatory cells. The specific EV surface signature discriminated patients with PA from controls, whereas after specific PA treatment the profile became similar to essential hypertension. Stimulation of human endothelial cells with PA-derived EVs resulted in the overexpression of 5 selected genes (AKT1-CALR-CSNK2A1-FN1-PIK3R1), previously identified by bioinformatic analysis as targets of differentially expressed EV antigens. Overexpression of CALR and FN1 was confirmed also at protein level. Our data suggest that EVs represent biomarkers of vascular inflammation and endothelial dysfunction in patients with PA and also potential biovectors contributing to accelerated organ damage by multiple signaling processes.