In vitro and in vivo studies of ICE inhibitors.

Interleukin-1 beta-converting enzyme (ICE) is a cysteine protease responsible for proteolytic activation of the biologically inactive interleukin-1 beta precursor to the proinflammatory cytokine. ICE and homologous proteases also appear to mediate intracellular protein degradation during programmed cell death. Inhibition of ICE is a new antiinflammatory strategy being explored by the design of both reversible inhibitors and irreversible inactivators of the enzyme. Such compounds are capable of blocking release of interleukin-1 beta from human monocytes. ICE inhibitors that cross react against multiple ICE homologs can also block apoptosis in diverse cell types. ICE inhibitors impart protection in vivo from endotoxin-induced sepsis and collagen-induced polyarthritis in rodent models. Further optimization of the current generation of peptidyl ICE inhibitors will be required to produce agents suitable for administration in chronic inflammatory and neurodegenerative diseases.