Sepsis-associated acute kidney injury in mice and humans elicits heterogeneous renal microvascular microRNA responses.

Microvascular endothelial cells play important roles in sepsis-associated acute kidney injury (SA-AKI). In this study, we focused on microvascular microRNAs changes following SA-AKI to identify microRNAs as novel druggable targets and microvasculature-related early biomarkers of SA-AKI. Using small RNA sequencing we identified 40 differentially expressed microRNAs in the renal microvasculature in response to SA-AKI. While the induction of most microRNAs was restricted to a single microvascular compartment, miR-21-5p levels were increased across the renal microvasculature in both mice and humans following SA-AKI. Functional assessment in vitro revealed that inhibition of hsa-miR-21-5p exacerbated endothelial inflammatory activation, suggesting a protective role of this microRNA in endothelial cells. Furthermore, patients with SA-AKI exhibited elevated hsa-miR-21-5p levels in plasma compared with critically ill sepsis patients without AKI. These results highlight the potential of hsa-miR-21-5p and other microRNAs as therapeutic targets and biomarkers in SA-AKI.