Evaluation of Immune Profiles and MicroRNA Expression Profiles in Peripheral Blood Mononuclear Cells of Long-Term Stable Liver Transplant Recipients and Recipients with Acute Rejection Episodes

Objective This study aimed to document the difference of immunophenotypes in peripheral blood mononuclear cells (PBMCs) between long-term stable liver transplant recipients and recipients with acute rejection. We also sought to identify whether there is any correlation between microRNA (miRNA) expression profile and the differential immunoprofile in these 2 groups to establish a specific miRNA biomarker to identify potential liver transplant recipients. Methods PBMCs were isolated from 53 stable liver transplant recipients (STA group) and 15 liver transplant recipients with repeated biopsy-proven rejection episodes admitted to our hospital. Immunoprofiles were analyzed by means of flow cytometry. Analysis of miRNA expression in the PBMCs was performed by means of real-time polymerase chain reaction. Results The immune profiling analysis showed increased frequency of peripheral natural killer cells and regulatory T cells in stable liver transplant recipients compared with the acute rejection recipients and healthy volunteers (P <.05). There was no significant difference in the immune cell levels (CD19⁺ B cells, CD4⁺ T cells, and CD8⁺ T cells) in PBMCs among the transplant recipient groups and healthy control subjects. Three miRNAs, miR-18b, miR-340, and miR-106b, were up-regulated in the PBMCs of the STA recipients compared with recipients with acute rejection. Conclusions These results suggest that miR-18b, miR-340, and miR-106b, which regulate the expression of specific immunophenotypes, can be used as potential biomarkers to identify long-term stable liver transplant recipients from recipients with acute rejection.