Function of miR-24 and miR-27 in Pediatric Patients With Idiopathic Nephrotic Syndrome

Abstract Background: The specific etiology and mechanism of idiopathic nephrotic syndrome (INS) in children remain unclear, so we investigated the pathogenesis of INS by measuring the effects two specific miRNAs on Th2 cells in children with this disease. Methods: Flow cytometry was used to measure the levels of Th2 cells and a cytometric bead array was used to measure the levels of IgE, interleukin (IL) -4, and IL-13. RT-PCR was used to measure the levels of miR-24 and miR-27 in CD4+TCD25− cells. PBMCs were isolated using Ficoll density gradient centrifugation, and transfected with different mimic or inhibitor miRNAs. RT-PCR was used to measure the expression of different RNAs, and flow cytometry was used to determine the percentages of Th2 cells. Results: Children with active INS had higher percentages of Th2 cells than healthy controls (P<0.05), but there was no significant difference for children in remission. The plasma levels of IgE, IL-4, and IL-13 were significantly increased in children with active INS (P<0.05). miR-24 and miR-27 were at lower levels in children with active non-atopic INS (P<0.05). Transfection experiments indicated that upregulation of each miRNA decreased the percentage of Th2 cells and the level of IL-4 (P<0.05), and down-regulation of each miRNA had the opposite effects (P<0.05). Conclusion: Children with active INS, with or without atopy, had higher levels of IgE, possibly related to their higher levels of IL-13 and IL-4 due to drift toward Th2 cells. miR-24 and miR-27 suppress the expression of Th2 cells and have a critical function in Th2 expression in INS.