Circulating microRNA Biomarkers in Cellular and Antibody-Mediated Heart Transplant Rejection

Abstract

<h3>Purpose</h3> Non-invasive monitoring of heart allograft health is an important clinical goal and circulating microRNAs (miRs) have been associated with acute rejection in limited studies. <h3>Methods</h3> The Genomic Research Alliance for Transplantation (GRAfT) is a multicenter prospective study. Patients with no history of rejection after transplant were selected as controls. Cases were patients with acute cellular rejection (ACR) or antibody-mediated rejection (AMR). Small RNA sequencing was performed on plasma samples collected at the time of an endomyocardial biopsy. Differential miR expression analysis and LASSO regression was used to develop ACR and AMR miR panels while adjusting for clinical covariates. The panels were validated in an independent sample from GRAfT and Stanford University. Receiver operating characteristic curves were generated and area under the curve (AUC) statistics are reported. Distinct ACR and AMR clinical scores were developed to translate gene expression data for clinical use. <h3>Results</h3> The GRAfT cohort had a median age of 52 years, with 35% females and 45% Blacks. We included 85 controls and 34 patients with rejection (20 ACR, 14 AMR). In ACR and AMR, using differential gene expression and regression analysis, we identified 11 and 15 miRs that accurately discriminated ACR and AMR (p<0.05). Independent validation of the miR panels within GRAfT led to excellent diagnostic accuracy for ACR AUC 0.92 (95% CI: 0.86-0.98) and AMR AUC 0.82 (95% CI: 0.74-0.90). The externally validated ACR AUC was 0.91 (95% CI: 0.82-0.99). Distinct ACR and AMR miR clinical scores were developed ranging from 0-100; using a threshold of 65 identified ACR with a sensitivity of 86%, specificity of 78% and negative predictive value of 98%, for AMR the respective performance was 82%, 84% and 97% (Figure). <h3>Conclusion</h3> The unique clinical ACR and AMR scores usher in an era whereby genomic biomarkers are used not only for rejection surveillance but permit accurate, non-invasive diagnosis of ACR and AMR.