Session Time: 2:15pm-3:45pm
Presentation Time: 3:03pm-3:15pm
Location: Room 120-ABC
Monitoring of kidney allograft status is important for the graft longevity. Conventional urinary markers are not sensitive and specific enough to diagnose graft injuries so far. Kidney biopsy is the current gold standard, however; not an ideal solution due to the invasive nature and the financial burdens to patients. Exosomes and microvesicles (EMV) are released into the urine from all the areas of the nephrons by encapsulating the functional cytoplasmic molecules of the cell of origin. EMV mRNA profiles of urine samples from kidney transplant patients were analyzed in order to predict kidney biopsy results in a non-invasive manner.
Material & Methods
Urine samples were collected from post-transplant patients (N=205) at multiple post-operative days. Post-transplant complications were diagnosed based on eGFR, urinary protein and kidney biopsy with Banff criteria. After urinary cells and casts were removed by low speed centrifugation, urine supernatants containing EMV were applied to EMV collection tubes (Hitachi Chemical Research Center, Inc. (HCR)), followed by mRNA isolation and cDNA synthesis using oligo (dT)-immobilized microplate (HCR) and real-time PCR. The obtained mRNA data were analyzed based on the diagnosis of post-transplant complications and Banff codes of kidney biopsy.
mRNA biomarker candidates were selected from literatures as well as the following criteria: 1. differentially expressed in kidney biopsy samples of post-transplant patients (NCBI GEO GSE36059), 2. highly expressed in urinary EMV of a healthy subject (unpublished data) and optionally 3. kidney or immune specific (NCBI UniGene). Among 68 mRNAs we analyzed, AQP1 and CXCL10 were dysregulated in T-cell mediated rejection (TCMR) (N=7) and ANXA1 and SLC12A1 were dysregulated in antibody-mediated rejection patients (ABMR) (N=20). Logistic regression analysis suggested that combinations of up to 7 genes including the above genes diagnose TCMR with 100% sensitivity and >95% specificity (AUC 0.9995), and ABMR with 100% sensitivity and >80% specificity (AUC 0.8906).
We discovered differentially expressed genes in TCMR and ABMR patients comparing to those with stable recovery. We further developed preliminary diagnostic formulas to identify these injuries using logistic regression analysis. Such formula will be a candidate of future diagnostics of TCMR and ABMR instead of kidney biopsy.
To cite this abstract in AMA style:Harada H, Murakami T, Yamamoto C, Mitsuhashi M. Non-Invasive Diagnosis of Post Kidney Transplant Complications by Urinary Exosomal mRNA Analysis [abstract]. Am J Transplant. 2015; 15 (suppl 3). https://atcmeetingabstracts.com/abstract/non-invasive-diagnosis-of-post-kidney-transplant-complications-by-urinary-exosomal-mrna-analysis/. Accessed May 5, 2021.
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