Naringin Inhibits Monocyte Adhesion to High Glucose-Induced Human Umbilical Vein Endothelial Cells

OBJECTIVE:To investigate the inhibitory effect of naringin on monocyte adhesion to high glucose-induced human umbilical vein endothelial cells (HUVECs).METHODS:Cultured HUVECs isolated from human umbilical cords were pretreated with or without naringin and induced with high glucose (33 mmol/L) for 48 h. Human monocyte THP-1 cells, after labeling with BCECF-AM, were co-cultured with the HUVECs for 30 min. The labeled THP-1 cells adhering to HUVECs were observed under fluoroscence microscope, and the inhibitory effect of naringin on the cell adhesion was evaluated by measuring the adhering cell density. Western blot analysis was used to detect the expressions of the adhesion molecules in the HUVECs, and reactive oxygen species (ROS) production in the HUVECs was measured using an oxidation-sensitive fluorescent probe (DCFH-DA). The nuclear extracts of the HUVECs were prepared to examine the expression of nuclear factor-kappa B (NF-kappaB) in the cell nuclei by Western blotting.RESULTS:HUVECs in high-glucose culture showed increased adhesion to THP-1 cells and enhanced expressions of the cell adhesion molecules, which were significantly attenuated by pretreatment with naringin (10-50 microg/ml). High glucose induced DCF-sensitive intracellular ROS production in the HUVECs, and this effect was inhibited by naringin pretreatment of the cells. Naringin also suppressed high glucose-induced increment of NF-kappaB expression in the cell nuclei of HUVECs.CONCLUSION:Naringin can suppress high glucose-induced vascular inflammation possibly by inhibiting ROS production and NF-kappaB activation in HUVECs.