Serum Levels of miR-155, miR-326, and miR-133b as Early Diagnostic Biomarkers for the Detection of Human Acute Heart Allograft Rejection in Comparison with Serum Cardiac Troponin T.

BACKGROUND: Acute heart allograft rejection occurs as a result of antibody-mediated rejection that presents during the first month after transplantation. Finding a non-invasive biomarker is essential for diagnosis of heart allograft rejection. In this research, we intended to compare expression levels of several microRNAs across cardiac troponin T levels between rejected patients (who died before one month following transplantation), non-rejected patients (who survived for at least one month after transplantation), and non-transplanted patients (CABG surgery patients). METHODS: Serum levels of miR-155, miR-326, and miR-133b were evaluated by the q-RT-PCR method. Furthermore, cardiac troponin T levels were measured by a highly sensitive electrochemiluminescence assay. Finally, the data were analyzed by independent sample t-test using SPSS 21® computer software. Results: It was observed that miR-326 and miR-155 expression levels increased after 24h and 72h of surgery in rejected patients compared with the two other groups, but these increases were not statistically significant. Moreover, the decrease in miR-133b expression level was non-significant after transplantation in the rejected group compared with the non-rejected group. However, cTnT levels in rejected patients increased significantly compared with the other groups (P < .05). After ROC curve analysis, the cTnT marker with the most area under the curve (AUC = 1.00, 95% confidence interval, 1.00 to 1.00; P = .006), had the best discriminatory power, and among microRNAs, miR-326 had the largest area under curve (AUC = 0.81), and consequently the highest discriminatory power. CONCLUSIONS: We demonstrated that troponin T can be a more efficient biomarker than miRNAs for early prediction of human death caused by acute heart rejection, and the ROC curves analysis verified this finding.