Identification of novel exosomal miRNAs associated with HBV reactivation after liver transplantation

Abstract

Background: HBV reactivation after liver transplantation (LT) is a significant problem leading to graft failure and worse survival of patients. However, post-LT HBV reactivation is hard to predict. Exosomal microRNAs (miRNAs) play pivotal roles in gene regulations and are useful prognostic and therapeutic targets for disease recurrence after surgery. We aimed to identify novel exosomal miRNAs for predicting and preventing HBV reactivation after LT. Methods: Serum RNAs were extracted from the HBV-reactivated LT patients at the first time of HBV reactivation (HBVreactive) and the latest follow-up time before HBV reactivation (HBVinactive). Low density array (LDA) consisting of 754 human microRNAs was conducted to compare the miRNA profiles in matched HBVreactive and HBVinactive samples of 8 patients. Differential expressed miRNAs were identified and validated in serum exosomes in 22 patients with post-LT HBV reactivation by quantitative RT-PCR. The correlations between exosomal miRNAs and HBV reactivation and pathogenesis in LT patients were characterized. Results: From the LDA analysis, we identified numerous miRNAs differentially expressed after HBVreactive samples (ranged from 67 to 215 miRNAs) compared to HBVinactive samples, with the number of upregulated miRNAs were significantly larger than the number of downregulated miRNAs. From clustering analysis, 15 significantly upregulated miRNAs in HBVreactive were identified (Fig.1). In the validation study, 3 novel exosomal miRNAs, miR-151-3P, miR-625-3p and miR-766, were identified to be significantly upregulated during HBV reactivation (Fig.2). The expression level of miR-766-3p was significantly correlated with miR-151-3P and miR-625-3p during HBV reactivation (Fig.3A). Importantly, the deregulation of exosomal miR-766 was significantly associated with HBV DNA copy number at the time of HBV reactivation (Fig.3B), suggesting that exosomal miR-766 may play functional roles in HBV reactivation. Conclusion: Exosomal miR-766 may be a promising prognostic biomarker and a potential therapeutic target for HBV reactivation.