MiRNA-486-5p Protects Against Kidney Ischemic Injury and Modifies the Transcriptome in Proximal Tubule and Endothelium

Background: Acute kidney injury (AKI) is a common clinical event with high morbidity and mortality. We previously demonstrated that injection of cord blood endothelial colony forming cell (ECFC)-derived exosomes, highly enriched in miRNA(miR)-486-5p, prevented ischemic kidney injury in mice. While preclinical models support involvement of several miRs in AKI, the direct effects of miR-486-5p on injury and the kidney transcriptome are unknown. Objective: We studied effects of miR-486-5p in mice with kidney ischemia-reperfusion (IR) injury, and compared the impact of miR-486-5p and ECFC-derived exosomes on the transcriptome of proximal tubules (PTs) and renal endothelial cells. Methods: Adult male mice were subjected to bilateral kidney ischemia (30 min), and injected via tail vein with or without vehicle, miR-486-5p mimic, ECFC-derived exosomes, or scramble miR at the start of reperfusion. Plasma and tissues were collected 24 hrs after reperfusion, and proximal tubular and endothelial cells were isolated for mRNA analysis by RNA-Seq. Results: In mice with kidney IR, injection of miR-486-5p mimic increased levels of miR-486-5p in proximal tubules and endothelial cells, and significantly improved plasma creatinine, histological injury, neutrophil infiltration, and apoptosis, compared to vehicle treatment. MiR-486-5p inhibited expression of phosphatase and tensin homolog (PTEN), and activated AKT. Similar results were observed with exosomes, but scramble miR had no effect. In proximal tubules, miR-486-5p or exosomes reduced expression of several AKI genes (e.g. Lcn2, Havcr1 and Krt20) and caused alterations in apoptotic genes compared to IR alone. In endothelium, miR-486-5p or exosomes caused milder effect than in PTs but still impacting on expression of injury-related genes. Conclusion: MiR-486-5p protects mice against ischemic kidney injury. Both miR-486-5p and exosomes reduce expression of apoptotic genes in PTs and endothelium. The results suggest that systemic delivery of miR-486-5p has therapeutic potential in ischemic AKI. Transcriptomic profile of endothelial cells from control (sham), acute kidney injury (AKI), acute kidney injury treated with miR-486-5p mimic (AKI+mimic),acute kidney injury treated with exosomes (AKI+ EXO) and acute kidney injury treated with scrambled miRNA (AKI+SCB) FVB male mice (n=3 except for AKI+ mimic n=2) The experiment also includes the same experimental groups with samples of proximal tubular cells from sham male mice (n=3), AKI male mice(n=3), AKI+ mimic male mice(n=2) , AKI+ EXO male mice (n=3), and AKI+ SCB male mice (n=3).