Inhibition of lipopolysaccharide-induced apoptosis by cilostazol in human umbilical vein endothelial cells

This work describes the pharmacological inhibition by cilostazol and its metabolites, OPC-13015 and OPC-13213, of the apoptosis in the human umbilical vein endothelial cells (HUVECs) damaged by lipopolysaccharide (LPS) in comparison with its analog, cilostamide. Cilostazol and OPC-31213 caused a significant suppression of cell death induced by LPS (1 mug/ml) in a concentration-dependent manner but a modest suppression by cilostamide and OPC-13015. These compounds potently inhibited the 5,5-dimethyl-1-pyrroline-1-oxide (DMPO)/ (OH)-O-. adduct formation and significantly reduced the increased intracellular reactive oxygen species (ROS) and tumor necrosis factor-alpha (TNF-alpha) production induced by LPS (1 mug/ml). An apoptotic death of HUVECs by 1 mug/ml LPS (DNA ladders on electrophoresis) was strongly suppressed by all these compounds. Incubation with LPS caused a marked decrease in Bcl-2 protein, which was significantly reversed by cilostazol and its analogs. The greatly increased Bax protein expression and cytochrome c release by LPS were, in contrast, suppressed by cilostazol and, to a lesser degree, by others. In conclusion, cilostazol and its analogs exert a strong protection against apoptotic cell death by scavenging hydroxyl radicals and intracellular ROS with reduction in TNF-alpha formation and by increasing Bcl-2 protein expression and decreasing Bax protein and cytochrome c release.