INDUCTION OF APOPTOTIC CELL-DEATH IN HUMAN ENDOTHELIAL-CELLS TREATED WITH SNAKE-VENOM - IMPLICATION OF INTRACELLULAR REACTIVE OXYGEN SPECIES AND PROTECTIVE EFFECTS OF GLUTATHIONE AND SUPEROXIDE DISMUTASES

Human vascular endothelial cells play a pivotal role in atheroscleroti c changes but are resistant to apoptotic inducers such as Fas ligand a nd it has been difficult to induce apoptosis. We developed an experime ntal model for the apoptosis in the endothelial cells by using snake v enom treatment. Snake venom was found to generate intracellular reacti ve oxygen species (ROS) in the endothelial cells, which leads to apopt osis as judged by electron microscopy as well as by DNA cleavage, Buth ionine sulfoximine (BSO) and diethyldithiocarbamate (DDC) accelerated the apoptosis, indicating intracellular glutathione and superoxide lev els play a critical role. Pretreatment with tumor necrosis factor (TNF ) or phorbol ester (TPA), which increases the Mn-SOD level, prevented the apoptosis. These data suggest that intracellular ROS enhances apop tosis whereas several anti-oxidants are protective in human endothelia l cells. The induction of apoptosis by ROS of endothelial cells may be related to initiation of atherosclerotic changes.