Biomarkers of acute and chronic human heart allograft rejection

Background: Cardiac transplantation is considered the primary therapy for patients with end-stage heart failure. However, the detection of chronic cardiac allograft rejection (expressed as cardiac allograft vasculopathy; CAV) remains an important unsettled issue in cardiac transplantation. The current gold standards for the diagnosis and monitoring of acute rejection and CAV are invasive in nature with risk for complications. From a clinical perspective, more accurate, minimally-invasive alternatives are clearly desirable. The goal of my thesis is to identify biomarkers of human heart allograft rejection, and assess their potential clinical utility and biological implications in the respective disease contexts. Central hypothesis: Peripheral blood-derived molecular biomarker panels provide a means for sensitive and specific diagnosis of acute and chronic cardiac allograft rejection, as well as helping to gain insight into the underlying mechanisms of rejection. Methods: Genomic biomarkers of acute cardiac allograft rejection (AR) and proteomic biomarkers of cardiac allograft vasculopathy (CAV) were identified via Affymetrix microarray analysis of whole blood samples and iTRAQ proteomic analysis of plasma samples, respectively, from cardiac transplant patients. From the genes differentially expressed between AR vs. Non-rejectors (NR), and differentially expressed proteins between CAV and Non-significant CAV (Non-CAV) subjects, biomarkers panels for AR and CAV were generated using classification methods. AR and CAV biomarkers were further analyzed for their biological implications using bioinformatical tools. Results: Microarray comparison between the AR and NR subjects revealed over 1000 differentially expressed genes, many of which that were associated with cellular functions involved in innate and humoral immunity. The 12-gene biomarker panel generated based on the differentially expressed candidates demonstrated 83% sensitivity and 100% specificity. Proteomic analysis of CAV versus Non-CAV plasma samples ultimately lead to the generation of an 18-protein biomarker panel which demonstrated 80% sensitivity and 89% specificity for CAV.Medicine, Faculty ofPathology and Laboratory Medicine, Department ofGraduat