Background: Preeclampsia (PE) is characterised by endothelial dysfunction and renal injury. Urinary extracellular vesicles (uEVs) provide a non-invasive source of kidney-derived microRNAs (miRNAs), which regulate biological pathways. However, the uEV miRNA profile remains poorly characterised in PE. This exploratory study aimed to characterise the uEV miRNA profile in PE using unbiased small RNA (miRNA) sequencing and validation.
Methods: In a prospective case-control study, uEVs were isolated from urine samples collected from women with PE and gestation-matched normotensive pregnant (NP) controls. A discovery cohort (30 NP, 30 PE) underwent small RNA sequencing. Differentially expressed miRNAs (fold change >1.5, P <0.05) were validated by quantitative polymerase chain reaction (qPCR) in an independent cohort (40 NP, 40 PE). uEVs were characterised with Western blot and nanoparticle tracking analysis (NTA).
Results: Small RNA sequencing identified six differentially expressed miRNAs (miR-1-3p, miR-95-3p, miR-143-3p, miR-199a-3p, miR-203a-3p, miR-513a-3p; P<0.05) in PE versus NP. Upon validation, miR-203a-3p was downregulated in PE (fold change 0.6, P=0.037). miR-203a-3p is associated with angiogenic, endothelial and inflammatory pathways. Western blotting confirmed the presence of EV proteins (TSG101 and CD9), kidney-associated protein NCC, and more frequent detection of placental alkaline phosphatase-positive vesicles in PE. NTA showed no differences in uEV size or concentration between groups.
Conclusions: uEV miR-203a-3p is downregulated in PE and may reflect dysregulation of molecular pathways involved in inflammation, endothelial dysfunction, and renal injury. This study provides novel insights into renal molecular alterations in PE and supports further investigation of uEV miRNAs as non-invasive biomarkers of kidney dysfunction in PE.