High glucose-associated endothelial cell injury plays an important role in the pathogenesis of diabetic vascular complications. This study was undertaken to explore the role of miR-155 in high glucose-induced endothelial dysfunction and the underlying molecular mechanisms.

Human umbilical vein endothelial cells (HUVECs) were divided into four groups: control group (5.5mmol/L glucose), HG group (33.3mmol/L glucose), HG+miR-155 inhibitor and HG+inhibitor-control group. Gene and protein expression levels were determined by Real-time PCR and Western blot, respectively. Cell viability was measured by MTT assay. Cell apoptosis and production of ROS were determined by flow cytometric analyses. The target relationship of miR-155 and gene mRNA were assessed by Dual-Luciferase reporter assay.

High glucose treatment upregulated the expression of miR-155 significantly. MiR-155 inhibition promoted cell viability and reduced apoptosis, prevented the overexpression of cleaved-Caspase-3, cleaved-Caspase-9 and Bax, promoted the expression of Bcl-2, downregulated the overexpression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), suppressed reactive oxygen species (ROS) production, inhibited the NF-κB signaling, activated nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling, promoted the endothelial NOS (eNOS)/NO expression in the high glucose-treated HUVECs. We subsequently demonstrated that miR-155 targeted the 3′-untranslated region (UTR) of eNOS, but neither Nrf2 nor HO-1.

Taken together, the data suggest that downregulation of miR-155 ameliorates high glucose-associated injury in HUVECs, and it may related with the inhibition of ROS/NF-κB signaling and the upregulation of HO-1 and NO.