Urinary Exosomal microRNA-451-5p Is a Potential Early Biomarker of Diabetic Nephropathy in Rats

Abstract

Non-invasive renal signatures can help in serial monitoring of diabetic patients. We tested whether urinary exosomal (UE) microRNA (miR) analysis could non-invasively predict renal pathology in diabetic rats during the course of diabetes. Diabetes mellitus (DM) was induced in male Wistar rats by a single intraperitoneal injection of streptozotocin (STZ, 50 mg/kg body weight). Non-diabetic control (CTRL) rats were injected with vehicle. Insulin (INS) treatment (5U/d, s.c.) was provided to 50% of the DM rats. Urine samples were collected at weeks 3, 6, and 9 following injections and UE prepared. An increase in miR-451-5p and miR-16, observed by pilot small RNA sequencing of UE RNA, was confirmed by quantitative real-time polymerase chain reaction (qPCR) and selected for further study. Subsets of rats were euthanized after 3, 6, and 9 weeks of diabetes for renal pathology analysis, including determination of the tubulointerstitial fibrotic index (TFI) and glomerulosclerotic index (GI) scores. qPCR showed a substantial rise in miR-451-5p in UE from DM rats during the course of diabetes, with a significant rise (median fold change >1000) between 3 and 6 weeks. Moreover, UE miR-451-5p at 6 weeks predicted urine albumin at 9 weeks (r = 0.76). A delayed but significant rise was also observed for miR-16. In contrast, mean urine albumin only increased 21% between 3 and 6 weeks (non-significant rise), and renal TFI and GI were unchanged till 9 weeks. Renal expression of miR-451-5p and miR-16 (at 10 weeks) did not correlate with urine levels, and moreover, was negatively associated with indices of renal pathology (r≥-0.70, p = 0.005 for TFI and r≥-0.6, p≤0.02 for GI). Overall, a relative elevation in renal miR-451-5p and miR-16 in diabetes appeared protective against diabetes-induced kidney fibrosis; while UE miR-451-5p may hold prognostic value as an early and sensitive non-invasive indicator of renal disease.

Epigenetic Regulations in Diabetic Nephropathy

“…Thirdly, in some cases, miRNA changes expression level in the early stage of DN, which related to fibrosis [62]. For example, Mohan et al reported that miR-451-5p and miR-16 in diabetes appeared to be protective against diabetes-induced kidney fibrosis, while UE miR-451-5p may hold prognostic value as an early and sensitive noninvasive indicator of renal disease [63]. Similar to miRNA, lncRNA also can help in serial monitoring of diabetic patients.…”

miR-451 Loaded Exosomes Are Released by the Renal Cells in Response to Injury and Associated With Reduced Kidney Function in Human

“…Urinary exosomes were isolated from rat and human urine samples by ultracentrifugation and characterized as previously described by us (Kalani et al, 2013;Mohan et al, 2016).…”

“…Besides its widely known dysregulation in malignancies, its overexpression in human coronary artery disease is now well appreciated (Zhang et al, 2010). With regards to kidney disease, dysregulation of miR-451 has been reported in human patients with DN and in mouse models of DN associated with mesangial hypertrophy (Wei et al, 2013;Mohan et al, 2016;Sun et al, 2016). In the previous study from our laboratory, we found a rise in miR-451 expression in uEs from diabetic rats as early as 6 weeks postdiabetes induction, and its levels continued to increase with disease progression.…”

MicroRNA as novel biomarkers and therapeutic targets in diabetic kidney disease: An update

“…miRNA‑29 levels in urine exosomes have been proposed as a biomarker of kidney fibrosis but their expression can be dynamic. In a recent study, Mohan et al reported that urinary exosomal miRNA‐451‐5p level was increased in diabetic rats 3 weeks prior to significant albuminuria and 3 weeks before histological changes of kidney fibrosis. In contrast, renal expression of miRNA‐451‐5p declined and was negatively associated with the indices of renal pathology during the progression of DKD.…”