Protection against TNF-induced liver parenchymal cell apoptosis during endotoxemia by a novel caspase inhibitor in mice

Excessive apoptotic cell death is implicated in a growing number of acute a nd chronic disease states. Caspases are critical for the intracellular sign aling pathway leading to apoptosis. The aim of this investigation was to ev aluate the efficacy and the mechanism of action of the novel caspase inhibi tor CV1013 in a well-characterized model of TNF-induced apoptosis. Administ ration of 700 mg/kg galactosamine/100 mug/kg endotoxin (GallET) induced hep atocellular apoptosis in C3Heb/FeJ mice as indicated by increased caspase-3 activity (706% above controls) and enhanced DNA fragmentation (3400% above controls) at 6 h. In addition, apoptosis was aggravated by the neutrophil- induced injury at 7 h (ALT activities: 4220 +/- 960 Un and 48 +/- 4% necros is). All animals died 8-12 h after Gal/ET treatment from shock and liver fa ilure. A dose of 10 or 1 mg/kg of CV1013 administered three times (3, 4.5, and 5.5 h after Gal/ET) effectively prevented caspase-3 activation and pare nchymal cell apoptosis at 6 h as well as the subsequent neutrophil-induced aggravation of the injury at 7 h after Gal/ET treatment. Animals treated wi th 10 mg/kg CV1013 survived for 24 h without liver injury. CV1013 reduced t he processing of caspase-3 and caspase-8. This suggests that CV1013 may hav e inhibited the small amount of active caspase-8 generated at the receptor level. Because of the multiple amplification loops used to activate the ent ire caspase cascade, blocking the initial intracellular signal by CV1013 wa s highly effective in preventing apoptotic cell death. CV1013 has therapeut ic potential for disease states with excessive apoptosis. (C) 2000 Academic Press.