Differential expression of urinary exosomal microRNAs in IgA nephropathy

Background Immunoglobulin A nephropathy (IgAN) is the most common type of primary glomerulonephritis in the world. Reliable biomarkers are required for the non-invasive diagnosis and monitoring of IgAN. This study aims to investigate the difference in urinary exosomal microRNA (miRNA) expression profiles between patients with IgA nephropathy (IgAN) and healthy controls, which may provide clues to identify novel potential non-invasive miRNA biomarkers for renal diseases. Methods Urine samples were collected from eighteen healthy controls and eighteen patients with IgAN. Differential centrifugation was performed to isolate exosomes from urine samples. High-throughput sequencing and real-time quantitative polymerase chain reaction (RT-qPCR) were sequentially used to screen and further validate miRNA expression profiles in urinary exosomes of patients with IgAN in two independent cohorts. Results Urinary exosomes were successfully isolated to obtain exosomal miRNAs. MiR-215-5p and miR-378i were significantly upregulated in urinary exosomes of patients with IgAN compared with healthy controls (P<.01), while miR-29c and miR-205-5p were significantly downregulated (P<.05). MiR-215-5p, miR-378i, miR-365b-3p and miR-135b-5p were found to have altered expression in patients with IgAN from validation cohorts, which was consistent with the high-throughput sequencing analysis. Conclusion This study suggests that there is a significant difference in urinary exosomal miRNA profiles between patients with IgAN and healthy controls. These exosomal miRNAs, such as miR-29c, miR-146a and miR-205 may potentially serve as novel non-invasive biomarkers for IgAN.