Transcriptomic analysis of urinary extracellular vesicles in hypertensive patients with primary aldosteronism

Objective: To perform transcriptomic analysis of RNA samples extracted from urinary extracellular vesicles (uEVs) of patients with primary aldosteronism (PA), subtype aldosterone-producing adenoma (APA), before and after adrenalectomy, and patients with essential hypertension (EH). Then, to compare the differentially expressed genes (DEGs) for evaluating gene expression differences between PA and EH, and PA before and after adrenalectomy. Design and method: Urinary extracellular vesicles were isolated using a commercially available precipitating reagent and differential centrifugations. RNA libraries were prepared according to the TruSeq Stranded Total RNA protocol and sequenced by NextSeq System (Illumina). Results: Gene set enrichment analysis on DEGs in 5 patients with PA compared to 8 EH subjects revealed several significantly overrepresented classes of transcripts, including ion binding, sodium ion transmembrane transport and collagen-containing extracellular matrix. Among the more interesting genes, we found some associated to the activity of voltage-dependent ion channels (CACNA2D1, CACNA2D4, CACNG2, SCN3A, SCN5A, SCN9A, SCN11A). Moreover, in order to identify potentially aldosterone-regulated genes, we focused on DEGs in common between the comparisons APA pre-surgery vs EH and APA pre surgery vs APA post-surgery. We found, among DEGs shared across these two groups, some transcripts involved in the regulation of extracellular matrix remodeling and Phosphoinositide 3-kinases pathway (CST3, EPHB2, ITGA5, PIK3R2). Conclusions: This study contributes to a more precise characterization of the molecular mechanisms underlying PA. To our knowledge, this is the first transcriptomic study on uEVs from patients with PA and EH, confirming evidence found in other studies on different tissues (biological fluids and adrenal tissue). Our results suggest that the mRNA content of these vesicles may reflect the pathophysiological processes occurring in the urinary tract and especially in the kidney.