Increased Serum And Urinary MicroRNAs In Children With Idiopathic Nephrotic Syndrome

BACKGROUND:Childhood nephrotic syndrome (NS) is the most frequent glomerμlar disease that presents during childhood, characterized by alterations in permselectivity at the glomerμlar capillary wall, resμlting in its inability to restrict the urinary loss of protein. The clinical hallmarks of NS are characterized by heavy proteinuria, edema, hypoalbuminemia and hyperlipidemia. The pathogenesis of idiopathic childhood nephrotic syndrome remains unclear. MicroRNAs (miRNAs) are a family of small non-coding RNAs of approximately19-24nucleotides that play important roles in various biological processes through their regμlation of posttranscriptional gene silencing via base pair binding to the3’untranslated region of their target mRNAs. Whether there is unique miRNA expression profiling in serum and urine of NS or miRNA can be as a new disease indicators? There is no research report. In our previous study, we have systematically discovered that miRNAs are stably present in blood and body fluids. The aim of this study was to investigate the profiles of serum and urinary miRNAs to explore their clinical value as novel biomarkers for idiopathic childhood nephrotic syndrome (NS).METHODS:We obtained serum samples from159NS children (24steroid resistant and135steroid sensitive),109age/gender-matched normal controls and44children with other kidney diseases. Serum miRNAs were analyzed by TaqMan Low Density Array followed by validation with a qRT-PCR assay in126individual samples. A TaqMan probe-based stem-loop quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay was employed to confirm the expression of selected miRNAs in serum samples from126patients and79controls, which were arranged in two phases. ROC curve analyses and logistic regression were then conducted to determine the diagnostic usefulness of the5selected miRNAs for NS. Moreover, paired serum samples were collected from50patients before and after treatment to determine the value of these miRNAs for condition assessment. In addition, candidate miRNAs were further examined in the urine samples of these patients.RESMLTS:TaqMan Low Density Array results showed that30were up regμlated in the NS group of the754miRNAs scanned. qRT-PCR identified five serum miR-3Oa-5p, miR-151-3p, miR-150, miR-191, and miR-19b were found to be highly increased in NS compared with controls (P<0.05) in a set of28patients and27controls. This results were further confirmed in another98NS and52controls with the fold change ranged from2.84～4.34(P<.0001). The area under the ROC curve and the odds ratio for the combined5serum miRNAs were0.902(95%CI,0.860-0.944, P<0.0001) and40.695(95%CI,6.056-103.145, P<0.0001), respectively. The concentrations of selected miRNAs were also measured in serum from children with other kidney diseases. Only miR-3Oa-5p, miR-150and miR-19b were found to be significanty increased in HSPN, while no significant difference was found in these serum miRNAs levels among the histological subtypes. All the5selected serum miRNAs declined significantly after treatment (compared with pre-treatment, P<0.0001). The urinary miR-3Oa-5p concentration was also increased in NS (P=0.001). Moreover, the concentrations of the5serum miRNAs and urinary miR-3Oa-5p markedly declined with clinical improvement of the patients.CONCLUSIONS:We determined that five distinct serum miRNAs and urinary miR-3Oa-5p were increased in NS children. These circμlating or urinary miRNAs may represent potential diagnostic and prognostic biomarkers for idiopathic pediatric NS.