Uromodulin mRNA from Urinary Extracellular Vesicles Correlate to Kidney Function Decline in Type 2 Diabetes Mellitus

Abstract

Background: Extracellular vesicles (EVs) enclose mRNA derived from their cell of origin and are considered a source of potential biomarkers. We examined urinary EV mRNA from individuals with diabetic kidney disease (DKD), chronic kidney disease, type 2 diabetes (T2DM), and obese and healthy controls to determine if such biomarkers had the potential to classify kidney disease and predict patients at higher risk of renal function decline. Methods: A total of 242 participants enrolled in this study. Urinary EV mRNA from all subjects were isolated by a filter-based platform, and the expression of 8 target genes were determined by quantitative polymerase chain reaction (qPCR). Changes in estimated glomerular filtration rate (eGFR) in 161 T2DM patients were evaluated for 2 consecutive years and compared with EV RNA profiles at baseline. Results: We observe that mild and severe DKD groups show a significant 3.2- and ­4.4-fold increase in UMOD compared to healthy controls and expression increases linearly from healthy, diabetic, and DKD subjects. UMOD expression is significantly correlated to albumin creatinine ratio (ACR), eGFR, and HbA1c. Using linear discriminant analyses with mRNA from severe DKD and T2DM as training data, a multi-gene signature classified DKD and ­non-DKD with a sensitivity of 93% and specificity of 73% with area under the receiver operating characteristic (ROC) curve (AUC) = 0.90. Although 6% of T2DM were determined to have a > 80% posterior probability of developing DKD based on this mRNA profile, eGFR changes observed within the 2-year follow-up did not reveal a decline in kidney function. Conclusion: Urinary EV UMOD mRNA levels are progressively elevated from T2DM to DKD groups and correlate with widely used eGFR and ACR diagnostic criteria. An EV mRNA signature could identify DKD with greater than 90% sensitivity and 70% specificity.

Bladder cancer detection by urinary extracellular vesicle mRNA analysis

“…Our previous studies employed an EV mRNA assay to conduct biomarker screenings for hematologic, kidney and ovarian disorders, where the assay performance such as sensitivity, linearity, and reproducibility was optimized and characterized [ 9 – 12 ]. In this retrospective feasibility study for bladder cancer, our objectives were to conduct a biomarker screening of bladder cancer using urine samples from urothelial cancer patients with various grades and stages and to evaluate diagnostic accuracy of the marker candidates compared to the conventional urine cytology and other assays.…”

New insight into the role of extracellular vesicles in kidney disease

“…For example, urinary EV UMOD mRNA levels are progressively elevated from T2DM to DKD groups and correlate with eGFR and ACR levels . We have recently isolated exosome released from podocyte in the urine, the vesicle structure was positive for the markers of both exosome and podocyte, CD9, AQP2 and nephrin.…”

Extracellular vesicles in type 2 diabetes mellitus: key roles in pathogenesis, complications, and therapy

“…EVs exist in various body fluids, such as blood, urine, saliva, and spinal fluid [27]. The commonly used methods for EVs isolation include ultracentrifugation, density gradients, precipitation, immuno‐affinity capture, size exclusion chromatography, and ultrafiltration [28–34]. (a) Currently, the “gold standard” for purification of EVs is ultracentrifugation, which typically consists of low‐speed centrifugation to remove cells and large vesicles and high‐speed ultracentrifugation to pellet EVs.…”