MicroRNA Profiling as a Novel Predictive Tool for Operational Tolerance in Pediatric Liver Transplantation: A Single-center Study

Background: This study aimed to identify serum microRNAs (miRNA) as a predictive tool for operational tolerance in pediatric liver transplantation (LT). Methods: Pediatric LT recipients were included in an immunosuppressant (IS) minimization protocol in our institution. Blood samples were collected at 2 stages: pre-protocol and post-completion. Ninety miRNAs expression was analyzed from blood samples using the NextAmp Analysis System and mirSCAN PanelChip (Quark Biosciences, Inc.). Participants were categorized into 3 groups: IS-free (complete withdrawal), IS-high (serum tacrolimus level > 2 ng/mL), and IS-low (serum tacrolimus level ≤ 2 ng/mL). Results: Between 2011 and 2019, 37 patients were enrolled in the IS minimization protocol at Taipei Veterans General Hospital. Of these, 13 patients (35.1%) successfully achieved IS-free status, whereas 24 (64.8%) remained non-IS-free. Eighteen patients with blood samples at pre-protocol and post-completion stage were included in the analysis. A total of 27 miRNAs exhibited significant differences in expression between the IS-free and IS-high groups at the pre-protocol stage. Additionally, 13 miRNAs showed significant changes in expression between the pre-protocol and post-completion stages in the IS-free group. miRNAs associated with immune suppression were expressed at higher levels in the IS-high group and at lower levels in the IS-free group at the pre-protocol stage. Conclusions: In this study, we identified 6 miRNAs-hsa-miR-21-5p, hsa-miR-22-3p, hsa-miR-30c-5p, hsa-miR-181b-5p, hsa-miR-20a-5p, and hsa-miR-125b-5p-that predict operational tolerance in pediatric LT at both the pre-protocol stage and during the minimization period. Notably, hsa-miR-125b-5p demonstrated perfect discriminative performance at the pre-protocol stage (area under the curve 1.00; sensitivity 100%; and specificity 100%) and showed significant changes in ΔCq between the pre-protocol and post-completion stages in the IS-free group. To our knowledge, this is the first report of miRNA biomarkers exhibiting such high accuracy for identifying operational tolerance in pediatric LT.