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Micro RNAs in urine as potential biomarkers for severity of hemorrhagic fever with renal syndrome

Objective: Micro RNAs (miRNAs) are a class of small RNAs, 18 – 25 nucleotides in length, that represent a way of posttranscriptional regulation of gene expression by binding to mRNAs and facilitating there inhibition or degradation depending on the degree of similarity. Besides intracellularly they have been detected in several bodily fluids, implicating a possible regulation of selected tissues or organs. Certain miRNAs found in urine can be predictors of disease outcome in various renal pathologies, e.g. glomerulonephritis, IgA or diabetic nephropathy. We measured, for the first time, levels of selected miRNAs in urinary samples of patients with hemorrhagic fever with renal syndrome (HFRS) after Puumala virus infection and compared them to patients with pyelonephritis and healthy controls. Methods: Midstream urinary samples were obtained upon hospitalization and before discharge from 30 patients with HFRS after Puumala virus infection and 15 patients with pyelonephritis. The control group consisted of 15 sex and age matched individuals. Urinary miRNA and a spike-in control RNA were isolated and transcribed into cDNA. A custom real-time PCR Array was designed for the detection of seven selected miRNAs (miR-21-5p, miR-24-3p, miR-27a-3p, miR-127-3p, miR-146a-5p, miR-155-5p, let-7e-5p). Laboratory and clinical parameters were correlated by descriptive statistics. Differences between two independent groups were calculated using non-parametric statistics, e.g. Mann-Whitney U test. Differences between more than two groups of numeric variables were determined through Kruskal-Wallis and ANOVA & Median test. The calculated correlations were evaluated with the Spearman rank correlation. Results: Except miR-146a-5p and miR-155-5p all have been readily detected in patients urine albeit low concentrations. In urinary samples of HFRS patients and patients with acute pyelonephritis, miR-21 and miR-27a were more abundant, while let-7e could be HFRS specific. In mild patients with HFRS only miR-21 and let-7e were deregulated, whereas in severe patients miR-24, miR-27a, and miR-127 were also altered. Conclusions: Here we show for the first time a distinct profile of miRNA abundance in urine of HFRS patients and patients with acute pyelonephritis, which could serve as HFRS biomarkers as they correlate significantly with urea and creatinine levels, which in turn are hallmarks of HFRS progression and severity.

HFRS; hantavirus; miRNA; urine

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