Characterization of the caspase inhibitor IDN-1965 in a model of apoptosis-associated liver injury.
Previous studies have shown that caspase inhibitors are effective at protecting against anti-Fas antibody (alpha-Fas)-mediated liver injury/lethality. The purpose of these experiments was to characterize more fully the efficacy of a broad-spectrum, irreversible caspase inhibitor, IDN-1965 (N-[(1,3-dimethylindole-2-carbonyl)valinyl]-3-amino-4-oxo-5-fluoropentanoic acid), in this model and the role of caspase inhibition in long-term protection. The ED(50) for IDN-1965 by i.p. administration, based on alanine aminotransferase activities, was 0.14 mg/kg. The caspase inhibitor was also efficacious when administered intravenously and orally (ED(50) values of 0.04 and 1.2 mg/kg, respectively). Histologically, marked reduction in Fas-induced apoptosis with IDN-1965 (1 mg/kg, i.p.) was apparent at 6 h. Also, caspase 3-like activities were decreased in a dose-dependent manner, but the inhibition of caspase activity was transient. Immunohistochemical studies demonstrated that IDN-1965 greatly reduced the activation of caspase 3. In survival studies, a single i.p. treatment of 1 mg/kg IDN-1965 or continuous i.p. infusion via osmotic pumps completely blocked lethality measured up to 7 days after alpha-Fas administration. IDN-1965 was also effective in inhibiting liver injury when administered as long as 3 h after or 1 h before alpha-Fas administration. Lastly, Western blot analysis demonstrated that processing of caspases 3, 6, and 8, as well as Bid (a protein responsible for the release of mitochondrial cytochrome C and amplification of the apoptotic cascade) was inhibited by IDN-1965. In conclusion, the broad-spectrum caspase inhibitor IDN-1965 is markedly effective at inhibiting Fas-mediated apoptosis by multiple routes of administration. The therapeutic potential of caspase inhibitors appears promising for the treatment of apoptosis-mediated liver injury based on potency and postinsult efficacy.
Hoglen
N C
NC
Department of Pharmacology, Idun Pharmaceuticals, Inc., La Jolla, California 92121, USA. nhoglen@idun.com
Hirakawa
B P
BP
Fisher
C D
CD
Weeks
S
S
Srinivasan
A
A
Wong
A M
AM
Valentino
K L
KL
Tomaselli
K J
KJ
Bai
X
X
Karanewsky
D S
DS
Contreras
P C
PC
D000410:Alanine Transaminase / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D061945:Caspase Inhibitors; D056486:Chemical and Drug Induced Liver Injury / Q000473:pathology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D007150:Immunohistochemistry; D007211:Indoles / Q000494:pharmacology*; D008099:Liver / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009842:Oligopeptides / Q000494:pharmacology*; D019014:fas Receptor / Q000235:genetics
D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D007211:Indoles; C118798:N-((1,3-dimethylindole-2-carbonyl)-valinyl)-3-amino-4-oxo-5-fluoropentanoic acid; D009842:Oligopeptides; D019014:fas Receptor; D000410:Alanine Transaminase