Deregulation of miR-21 Contributes to Differential Macrophage Activation in Acute Kidney Injury in Aged Mice

Age-dependent renal changes increase the risk for acute kidney injury (AKI). The recruitment and activation of macrophages (M) is a prominent feature in this pathology wherein, distinct subsets of macrophages contribute to inflammation (M1) and tissue remodeling (M2). Recent studies suggest that microRNAs (miRs) play a significant role in AKI and functional recovery. The miRs are small non-coding RNA's which inhibit mRNA transcripts or block protein translation thus affecting the microenvironment a vital factor in the differentiation of macrophages to M1 and M2 phenotype. In this study, we determined whether deregulation of miR-21 contributes to macrophage polarization in renal ischemia reperfusion injury in aged mice. Young (12-14 wks) and aged (72-75 wks) wild type mice underwent bilateral renal ischemia for 25 minutes followed by 7 days reperfusion. Plasma creatinine and kidney injury molecule-1 measurement revealed severe renal dysfunction in aged mice vs. young. The level of miR-21 was increased in a...