SUN-236 CIRCULATING EXTRACELLULAR VESICLES FROM PATIENTS WITH PRIMARY ALDOSTERONISM INCREASE CELL STRESS-RELATED PROTEINS AND PROMOTE ENDOTHELIAL DYSFUNCTION

Abstract Disclosure: J.A. Pérez: None. A. Tapia-Castillo: None. A. Martinez-Garcia: None. P. Carrion: None. M.P. Hernandez: None. R. Pinilla-Quinteros: None. R. Baudrand: None. C.E. Fardella: None. C.A. Carvajal: None. Primary Aldosteronism (PA) is the most common cause of secondary arterial hypertension, with a prevalence of 6-10%. Patients with PA exhibit cardiovascular (CV) damage, including endothelial dysfunction, primarily driven by aldosterone-MR activation. Recently, extracellular vesicles (EVs) have been suggested as potential mediators of this damage. Therefore, determining the protein cargo of EVs from PA patients and assessing their effects in ex vivo models is encouraged to better understand their role in PA-associated CV damage. Objective: To characterize the protein cargo of circulating EVs from PA subjects and evaluate their role in the expression of endothelial dysfunction markers in vitro. Methods: We performed a cross-sectional and experimental study including 30 adults of both sexes with similar age and BMI, classified as either essential hypertensive (EH) patient, or PA patient (aldosterone >9 ng/dL and PRA <1 ng/mL*h). Circulating EVs were isolated from all subjects using ultracentrifugation, and characterized by NTA and w-blot, and their cargo was assayed by LC-MS/MS proteomics. Afterwards, human endothelial cells (EA.hy926) were incubated with circulating EVs from both study groups for 24 hours and stimulated with 100 nM of aldosterone during the last 6 hours of incubation. Gene expression of endothelial dysfunction markers as ICAM-1 and NOS3 was assessed by RT-qPCR. Results were expressed as fold change (FC) and standard deviation (±SD). Data were analyzed using the Mann-Whitney test (GraphPad Prism v10). Results: The proteomic analysis identified 387 proteins in circulating EVs. Of these, 9 were significantly upregulated (>1.5-fold), and 3 were downregulated (<1.5-fold) in the PA group compared to the EH group. EVs from PA subjects were enriched in ATP5A1 (p<0.01), CAT (p=0.01), and CASP14 (p=0.04), proteins implicated in cellular stress response (p<0.01) endothelial cell migration regulation (p<0.01). Furthermore, we observed an increase in ICAM-1 expression (FC=10.7±1.5; p<0.01) and a decrease in NOS3 expression (FC=0.42±0.18; p=0.02) exclusively when endothelial cells were stimulated with circulating EVs from PA subjects in the presence of aldosterone. Conclusion: Proteomic analysis of circulating EVs from PA subjects revealed its enrichment in ATP5A1, CAT, and CASP14 proteins, which are related to the adaptive responses to cellular stress. Additionally, EVs from PA subjects modulate the expression of endothelial dysfunction markers ICAM-1 and NOS3 ex vivo. These findings suggest that circulating EVs from PA patients are loaded with stress-related proteins and its cargo could affect the normal endothelium function in aldosteronism. Presentation: Sunday, July 13, 2025