Small RNA Sequencing of Human Urinary Extracellular Vesicles Reveals Association of High‐Sodium Diet With Renal Proinflammatory Pathways

Background: High sodium intake is associated with arterial hypertension and cardiovascular disease, through mechanisms that go beyond hemodynamic changes, including endothelial dysfunction, oxidative stress, and induction of a proinflammatory milieu. The aim of this study was to assess the role of dietary sodium modulation on renal pathophysiology through evaluation of small RNA cargos on urinary extracellular vesicles. Methods: Fourteen high-risk normotensive subjects with normal kidney function were prospectively enrolled to undergo a low-sodium diet followed by a high-sodium diet (HSD). The urinary extracellular vesicles were isolated from a 24-hour urine collection at the end of each diet phase and profiled by small RNA sequencing. Selected differentially expressed miRNAs were validated in human proximal tubular cell line (human kidney 2 cells) to assess miRNA-mRNA target interactions. Results: We identified 111 small RNA species, of which 30 were significantly different between the low-sodium diet and HSD. Bioinformatic network analysis showed that pathways related to the innate and adaptive immune system, interleukin and interferon signaling were enriched in the HSD, whereas pathways related to PPARα (peroxisome proliferator-activated receptor α) regulation were enriched in the low-sodium diet. In human kidney 2 cells, the inhibition of miR-320b, downregulated in the HSD, increased ICAM-1 (intercellular adhesion molecule 1), with renal proinflammatory effects. The inhibition of miR-10b-5p, downregulated in the low-sodium diet, increased PPARα, which has an antifibrotic and anti-inflammatory role in the kidney. Conclusions: Small RNA characterization from extracellular vesicles revealed that an HSD is associated with proinflammatory changes, potentially contributing to sodium-induced low-grade renal inflammation.