Small-RNA sequencing of human urinary extracellular vesicles reveals association of high sodium diet with renal pro-inflammatory 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 pro-inflammatory 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 (uEVs). Methods Fourteen high-risk normotensive subjects with normal kidney function were prospectively enrolled to undergo a low sodium diet (LSD) followed by high sodium diet (HSD). The uEVs were isolated from a 24h urine collection at the end of each diet phase and profiled by small RNA sequencing. Selected differentially expressed microRNAs (miRNAs) were validated in human proximal tubular cell line (HK-2 cells) to assess miRNA-mRNA target interactions. Results We identified 111 small RNA species of which 30 were significantly different between LSD and HSD. Bioinformatic network analysis showed that pathways related to the innate and adaptive immune system, interleukin and interferon signalling were enriched in HSD, whereas pathways related to peroxisome proliferator-activated receptor alpha (PPARa) regulation were enriched in LSD. In HK-2 cells, the inhibition of miR-320b, down-regulated in HSD, increased intercellular adhesion molecule 1 (ICAM-1), with renal pro-inflammatory effects. The inhibition of miR-10b-5p, down-regulated in LSD, increased PPARa, which has an anti-fibrotic and anti-inflammatory role in the kidney. Conclusions Small RNA characterization from uEVs revealed that HSD is associated with pro-inflammatory changes, potentially contributing to sodium-induced low-grade renal inflammation. Overall design: Fourteen high-risk normotensive subjects with normal kidney function were prospectively enrolled to undergo a low sodium diet (LSD) followed by high sodium diet (HSD). The uEVs were isolated from a 24h urine collection at the end of each diet phase and profiled by small RNA sequencing.