Selected miRNAs in Urinary Extracellular Vesicles Show Promise for Early and Specific Diagnostics of Diabetic Kidney...

Diabetic kidney disease (DKD) is a health burden that lacks specific and early diagnostic biomarkers. For their discovery, we sequenced urinary extracellular vesicle miRNAs in a type 1 diabetes cohort of males with and without DKD. The results were replicated by sequencing or qPCR in two independent cohorts and six published datasets, including type 1 and 2 diabetes, and both sexes. We also validated stable reference gene candidate miRNAs. Chronic kidney disease, hypertensive nephropathy, IgA nephropathy, polycystic kidney disease, kidney stones, prostate cancer and non-diabetic cohorts served as additional controls. MiRNAs changed due to urine collection type or centrifugation before storage were excluded. We analyzed differentially expressed miRNAs and their correlations with clinical measurements, receiver operating characteristic curves and target mRNAs, proteins and pathways, incorporating single-cell data and circulating proteins of type 1 and 2 diabetes cohorts. By studying the uEV miRNAs (N = 490 individuals total) and plasma proteins (N = 4335), we pinpointed 6 stable miRNAs, 11 differentially expressed miRNAs, 9 target proteins and 16 DKD-associated pathways. Differentially expressed miRNAs overlapped between diabetes subtypes and sexes, with strongest evidence for miR-192-5p, miR-146a-5p, miR-486-5p and miR-574-5p. The miRNAs alone or combined with clinical measurements classified individuals with the fastest kidney function decline (sensitivity 0.75-1.00, specificity 0.83-1.00) even in the normoalbuminuria group. The differentially expressed miRNAs did not cluster the control cohorts except for the chronic kidney disease cohort, which showed some clustering based on proteinuria status. Altogether, the miRNAs showed potential to identify early kidney function decline and may target key kidney cells, mRNAs, proteins and pathogenic mechanisms in DKD.