Exploratory circulating miRNA profile associated with cardiac allograft antibody-mediated rejection: A pilot single-center study

BACKGROUNDHeart transplantation remains the definitive treatment for patients with end-stage heart failure.However, long-term outcomes are compromised by acute cellular rejection (ACR), antibody-mediated rejection (AMR), and cardiac allograft vasculopathy (CAV), a chronic form of transplant vasculopathy.Current post-transplant allograft surveillance relies primarily on endomyocardial biopsy and coronary angiography, both of which are invasive, associated with procedural risks, costly, and complicated for frequent monitoring.Circulating microRNAs (miRNAs) have emerged as promising liquid biopsy candidate markers for the non-invasive assessment of transplant injury.Nevertheless, reliable molecular markers capable of discriminating between the distinct pathological phenotypes of rejection and graft injury remain unavailable.AIM To evaluate circulating miRNAs as candidate biomarkers for detecting rejection in heart transplant recipients within the first five years post-transplantation. METHODS Plasma samples were collected from 20 heart transplant recipients, including three with ACR (R1/Grade 2), four with severe AMR (one pAMR2, three pAMR3), five with CAV (moderate CAV2), and eight non-rejection (NR).Circulating miRNA profiles were generated by next-generation sequencing using the TruSeq Small RNA Library Prep Kit (Illumina, United States).Differential expression and bioinformatic analysis, including functional enrichment, were performed using miRge3.0,DESeq2, miRBaseConverter, and clusterProfiler.Statistical analyses were conducted in R (version 4.4.2). RESULTSAfter filtering low-abundance transcripts, a total of 642 miRNAs were detected across all samples.Following apeglm shrinkage, hsa-miR-193b-5p, hsa-miR-125b-5p, and hsa-miR-5588-5p were significantly upregulated in AMR group compared to NR, CAV, and ACR groups (p adj < 0.05).No significant differentially expressed (DE) miRNAs were identified betwee ACR and CAV, ACR and NR, or CAV and NR groups after shrinkage correction.Notably, hsa-miR-193b-5p retained a significant association with AMR after exploratory adjustment for contemporaneous anti-human leukocyte antigen antibody status, demonstrating a large effect size (shrunken log 2 fold change > 2.5).DE miRNAs targeted biological processes related to cellular stress responses, cell adhesion, immune activation, and tissue remodeling. CONCLUSIONOur study highlights hsa-miR-193b-5p, hsa-miR-125b-5p, and hsa-miR-5588-5p as exploratory candidate biomarkers associated with AMR.Validation in larger independent cohorts is required before any clinical application.