Identification of Common Blood Gene Signatures for the Diagnosis of Renal and Cardiac Acute Allograft Rejection

Li Li,Helen Luikart,Silke Roedder,Andrew Yang,Minnie M Sarwal,Lihua Ying,Tara Sigdel,Hannah Valantine,Kiran Khush,Szu-Chuan Hsieh,Christian Schönbach

doi:10.1371/journal.pone.0082153

Abstract

To test, whether 10 genes, diagnostic of renal allograft rejection in blood, are able to diagnose and predict cardiac allograft rejection, we analyzed 250 blood samples from heart transplant recipients with and without acute rejection (AR) and with cytomegalovirus (CMV) infection by QPCR. A QPCR-based logistic regression model was built on 5 of these 10 genes (AR threshold composite score>37% = AR) and tested for AR prediction in an independent set of 109 samples, where it correctly diagnosed AR with 89% accuracy, with no misclassifications for AR ISHLT grade 1b. CMV infection did not confound the AR score. The genes correctly diagnosed AR in a blood sample within 6 months prior to biopsy diagnosis with 80% sensitivity and untreated grade 1b AR episodes had persistently elevated scores until 6 months after biopsy diagnosis. The gene score was also correlated with presence or absence of cardiac allograft vasculopathy (CAV) irrespective of rejection grade. In conclusion, there is a common transcriptional axis of immunological trafficking in peripheral blood in both renal and cardiac organ transplant rejection, across a diverse recipient age range. A common gene signature, initially identified in the setting of renal transplant rejection, can be utilized serially after cardiac transplantation, to diagnose and predict biopsy confirmed acute heart transplant rejection.

Highlights

Despite improvements in immunosuppressive therapy over the years, approximately 30–40% of heart transplant recipients require treatment for acute rejection (AR) in the first year after transplantation [1]
These genes were indicative of histological acute rejection in both children and adults, as our study in renal AR [11] was performed in pediatric and young adult renal allograft recipients and the present study in cardiac AR was performed in adult heart transplant recipients
It was possible to narrow the original 10-gene panel to an even smaller set of 5-genes that were not confounded by clinical variables, such as transplant recipient age and sex, time posttransplant, or innate immune activation, discriminating AR from concomitant CMV infection

Summary

Introduction

Despite improvements in immunosuppressive therapy over the years, approximately 30–40% of heart transplant recipients require treatment for acute rejection (AR) in the first year after transplantation [1]. Most heart transplant recipients undergo routine EMB procedures up to 15 times in the first year, and more frequently if rejection is detected. This procedure is limited by sampling error and inter-observer variability [3,4]. Correlation studies of gene expression profiles in peripheral blood samples of pediatric and young adult renal transplant patients with biopsy-proven acute rejection identified a highly regulated set of 10 genes by microarray analysis (CFLAR, DUSP1, IFNGR1, ITGAX, PBEF1, PSEN1, RNF130, RYBP, MAPK9, and NKTR), which was subsequently validated by QPCR, and which by logistic regression analysis yielded a probability score for noninvasive diagnosis of biopsy confirmed renal AR in pediatric and young adult patients [11]

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