Estimation of Circulating Micrornas As Biomarkers in Early Stages of Chronic Kidney Disease

Background. Chronic kidney disease (CKD) is a progressive disorder that affects 10–13% of the worldwide population. The conventional biomarkers, like serum creatinine and estimated glomerular filtration rate (eGFR), have poor sensitivity in detecting early stage CKD, especially as it relates to Type 2 Diabetes Mellitus (T2DM). Recent studies suggest that circulating microRNAs (miRNAs) are sensitive molecular markers of renal pathology. Objectives. This study quantified the serum levels of miR-21, miR-155 and miR-192 in early-stage CKD patients with or without co-existing T2DM and determined the diagnostic performance of these microRNAs compared to cystatin C and eGFR. Methods. A case-control study was conducted with a total of 100 participants classified into three groups; healthy controls (n = 30), CKD patients with T2DM (n = 35) and CKD patients without T2DM (n = 35). The expression of serum miRNA was measured with real-time quantitative PCR using the 2⁻ΔΔCt method, U6 snRNA as internal reference. Cystatin C was determined by particle-enhanced immunonephelometry; eGFR was calculated using the CKD-EPI equation. Statistical analyses were performed using Kruskal-Wallis test, Spearman partial correlations, receiver operating characteristic (ROC) analysis, and multivariate logistic regression. Results. Significant upregulation of all three miRNAs in both CKD groups (P < 0.001) with a differing magnitude of fold-change compared with controls and the highest amplification for miR-192 was detected. ROC analysis identified miR-192 to be the best performing single biomarker (AUC = 0.937; 95% CI: 0.880–0.978). Spearman partial correlation networks showed strong positive relations of miRNAs with cystatin C (ρ = 0.74–0.80) and stronger negative associations with eGFR (ρ = −0.69 to −0.78). Conclusions. Circulating miR-21, miR-155 and miR-192 are promising minimally invasive biomarkers better than conventional markers for early CKD detection. Cystatin C was co-measured with it, yielding a highly accurate diagnostic panel especially in the diabetic nephropathy sub-phenotype. Clinical applicability requires validation in large multicentre cohorts. Keywords: biochemical markers, chronic kidney disease, cystatin C, eGFR, microRNA, ROC analysis