Role of peripheral blood microRNA-181b in acute vascular rejection after renal transplantation

Objective: To investigate the role of peripheral blood microRNA-181b in acute vascular rejection after renal transplantation. Methods: Thirty-four patients admitted to our hospital for initial renal transplantation from January 2013 to December 2016 were enrolled in this study. The patients were assigned to either the acute vascular rejection group (n=14) or the non-acute vascular rejection group (n=20) according to the acute vascular rejection in their transplanted kidneys. The miR-181b levels in peripheral blood of all the patients were detected using real-time polymerase chain reaction (PCR) preoperatively, at 1 week, 2, 3, and 4 weeks postoperatively, respectively. Normal peripheral blood mononuclear cells were stratified into the active subgroup and the inactive subgroup according to phytohemagglutinin stimulation profiles. Expression levels of miR-181b were detected by the real-time PCR and compared between the two subgroups. Patients with acute vascular rejection were stratified into the steroid-sensitive subgroup and the steroid-tolerable subgroup according to their sensitivity to hormone therapy after 2 weeks of hormone pulse therapy. And the real-time PCR was applied to detect and compare the expression levels of peripheral blood miR-181b of both groups. The receiver operating characteristic (ROC) curve was used to analyze and evaluate the predictive value of peripheral blood miR-181b in acute vascular rejection after renal transplantation. Results: Expression levels of peripheral blood miR-181b in the acute vascular rejection group were significantly lower than those of the non-acute vascular rejection group at different time points of 1, 2, 3, and 4 weeks, postoperatively (all P<0.001). The expression level of miR-181b in peripheral blood mononuclear cells activated by phytohemagglutinin was significantly lower than that in the inactive subgroup (1.05 +/- 0.11 vs 0.36 +/- 0.09, P<0.001). As compared with the steroid-tolerable subgroup, the expression level of miR-181b in the steroid-sensitive subgroup was markedly higher (0.48 +/- 0.07 vs 0.64 +/- 0.08, P<0.001). The ROC curve showed that the detection of expression level of miR-181b was a predictor of acute vascular rejection after renal transplantation. Conclusion: The expression level of peripheral blood miR-181b was reduced in the transplanted kidney with acute vascular rejection. Monitoring of the miR-181b levels could be one of the markers for assessment of acute vascular rejection after renal transplantation.