Urinary Exosomal MicroRNAs as New Noninvasive Biomarkers of IgA Nephropathy

Immunoglobulin A nephropathy (IgAN) is the most common type of primary glomerulonephritis. It is very important to find new noninvasive biomarkers for the diagnosis and treatment of IgAN. The purpose of this study was to explore the clinical value of urinary exosomal miRNAs in IgAN. In this study, urinary exosomes were isolated from 29 IgAN patients and 29 healthy controls. The miRNA was analyzed by high-throughput sequencing. The expression of hsa-miR-451a and hsa-let-7d-3p was examined by real-time quantitative polymerase chain reaction (RT-qPCR). The diagnostic value of miRNAs was evaluated using receiver operating characteristic (ROC) curves. Here, hsa-miR-451a and hsa-let-7d-3p were upregulated in IgAN patients compared with healthy controls. We evaluated the diagnostic value of hsa-miR-451a and hsa-let-7d-3p using ROC curves; hsa-miR-451a (AUC = 0.805, p = 0.001), hsa-mir-7d-3p (AUC = 0.76, p = 0.0049), and the combination of hsa-miR-451a and hsa-let-7d-3p (AUC = 0.8125, p = 0.0007). Hsa-miR-451a has correlations with Lee's grades (r = 0.511, p = 0.021), and 24-h urinary protein excretion (UPE; r = 0.557, p = 0.011). Hsa-let-7d-3p showed correlations with Lee's grades (r = 0.6, p = 0.005), UPE (r = 0.518, p = 0.019), serum creatinine (r = 0.564, p = 0.01), and estimated glomerular filtration rate (r = -0.532, p = 0.016). According to the Oxford classification, for hsa-miR-451a, S0 had lower levels than S1 (p = 0.016); for hsa-mir-7d-3p, M0 had lower levels than M1 (p = 0.05). These findings suggest that hsa-miR-451a and hsa-let-7d-3p may serve as noninvasive biomarkers for the evaluation of IgAN.