Caspase-1-inhibitor ac-YVAD-cmk reduces LPS-lethality in rats without affecting haematology or cytokine responses

Abstract

The effect of acetyl-tyrosyl-valyl-alanyl-aspartyl-chloromethylketone (ac-YVAD-cmk), an irreversible caspase-1 (IL-1 β converting enzyme, ICE) inhibitor on mortality, leukocyte and platelet counts and cytokine levels was investigated in a double-blind rat model of endotoxaemia. Intravenous (i.v.) bolus administration of lipopolysaccharide (LPS) (25-75 mg kg-1, n=12 per group) to anaesthetized rats induced a dose dependent increase in mortality over 8 h (LD50 = 48 mg kg-1). During this period, animals became leukopenic and thrombocytopenic. Serum levels of IL-β, IL-6, and TNF-α were highly elevated. Pretreatment of rats with ac-YVAD-cmk at a dose of 12.5 μmol kg-1 significantly reduced mortality from 83 to 33% using Log Rank analysis. However, ac-YVAD-cmk did not modify blood cell counts or cytokine profiles as compared with the LPS-drug vehicle group. These data lay credence to the potential importance of caspase-1-inhibition in modifying the inflammatory response to endotoxin. Further investigations are warranted in understanding the relationship between caspase-1 inhibition, cytokine production and animal survival in different experimental paradigms of sepsis.