Non-Invasive Diagnosis for Acute Rejection Using Urinary mRNA Signature Reflecting Allograft Status in Kidney Transplantation

Abstract

Urine has been regarded as a good resource based on the assumption that urine can directly reflect the state of the allograft or ongoing injury in kidney transplantation. Previous studies, suggesting the usefulness of urinary mRNA as a biomarker of acute rejection, imply that urinary mRNA mirrors the transcriptional activity of the kidneys. We selected 14 data-driven candidate genes through a meta-analysis and measured the candidate genes using quantitative PCR without pre-amplification in the cross-sectional specimens from Korean kidney transplant patients. Expression of 9/14 genes (CXCL9, CD3ϵ, IP-10, LCK, C1QB, PSMB9, Tim-3, Foxp3, and FAM26F) was significantly different between acute rejection and stable graft function with normal pathology and long-term graft survival in 103 training samples. CXCL9 was also distinctly expressed in allografts with acute rejection in in situ hybridization analysis. This result, consistent with the qPCR result, implies that urinary mRNA could reflect the magnitude of allograft injury. We developed an AR prediction model with the urinary mRNAs by a binary logistic regression and the AUC of the model was 0.89 in the training set. The model was validated in 391 independent samples, and the AUC value yielded 0.84 with a fixed manner. In addition, the decision curve analysis indicated a range of reasonable threshold probabilities for biopsy. Therefore, we suggest the urine mRNA signature could be used as a non-invasive monitoring tool of acute rejection for clinical application and could help determine whether to perform a biopsy in a recipient with increased creatinine.

Development and validation of urinary exosomal microRNA biomarkers for the diagnosis of acute rejection in kidney transplant recipients

“…Majority of the studies that have investigated biomarkers for rejection with respect to kidney transplantation have used different threshold values for the discovery and validation stages, thereby limiting their application in clinical practice ( 54 ). In fact, we have recently demonstrated that fixed cut-off values can be useful in urinary mRNA-based non-invasive diagnosis of AR ( 55 ). Hence, an important consideration of our study is the application of a fixed cut-off value during the assessment of the validation cohort.…”

Urinary mRNA Signatures as Predictors of Renal Function Decline in Patients With Biopsy-Proven Diabetic Kidney Disease

“…Urine is a valuable source for identifying relevant biomarkers associated with kidney diseases as it is generated directly from the kidneys and can be collected non-invasively. We have previously demonstrated the utility of urinary mRNAs and proteins as diagnostic and prognostic biomarkers in various renal conditions such as transplant rejection, primary glomerular diseases, and DKD (18,(22)(23)(24)(25)(26)(27)(28). Recent (29).…”

“…Normalization of urinary mRNA expression data is a critical issue in biomarker research; however, optimal normalization strategies for mRNA remain controversial ( 41 ). In this study, we used 18S rRNA rather than urine creatinine for the normalization of urinary mRNAs expression data as we have previously demonstrated this strategy to be useful in identifying urinary mRNA biomarkers ( 22 , 28 ). Further investigations are required to determine whether urine creatinine may be better for normalization of urinary mRNA expression data.…”

Identification and detection of microRNA kidney disease biomarkers in liquid biopsies

“…These probes then facilitate surface immobilisation, and the output is quantified using a fluorescence spectrophotometer. A recent study by Seo et al [24] used a combination of online meta-analysis, nCounter-based detection and RT-qPCR of urinary exosomal miRNAs to identify novel biomarkers of acute rejection following kidney transplant, in which screening highlighted upregulated miR-21, miR-31, miR-155, miR-210, miR-223-3, miR-373 and downregulation of miR-4488 and miR-4532.…”