Lazaroids U83836E and U74389G are potent, time-dependent inhibitors of caspase-1

Interleukin-1β converting enzyme (ICE): A comprehensive review on discovery and development of caspase-1 inhibitors

Caspase-1 is a critical mediator of the inflammatory process by activating various pro-inflammatory cytokines such as pro-IL-1β, IL-18 and IL-33. Uncontrolled activation of caspase-1 leads to various cytokines-mediated diseases. Thus, inhibition of Caspase-1 is considered therapeutically beneficial to halt the progression of such diseases. Currently, rilonacept, canakinumab and anakinra are in use for caspase-1-mediated autoinflammatory diseases. However, the poor pharmacokinetic profile of these peptides limits their use as therapeutic agents. Therefore, several peptidomimetic inhibitors have been developed, but only a few compounds (VX-740, VX-765) have advanced to clinical trials; because of their toxic profile. Several small molecule inhibitors have also been progressing based on the three-dimensional structure of caspase-1. However there is no successful candidate available clinically. In this perspective, we highlight the mechanism of caspase-1 activation, its therapeutic potential as a disease target and potential therapeutic strategies targeting caspase-1 with their limitations.

Lazaroid U-74389G in liver ischemia-reperfusion injury: A swine model

Reactive oxygen species have a key role in liver ischemia-reperfusion (I/R) injury. In the present study, the effect of the anti-oxidant compound lazaroid U-74389G in preventing liver I/R injury was investigated in a swine model. Ischemia was produced by portal vein occlusion. Two sets of experiments were performed, each with two groups (n=7 per group). In the first group, the potential protective effect of an intracaval injection of U-74389G after a 30-min ischemia, followed by a 60-min reperfusion period was assessed (biopsies at 0, 15, 30 and 90 min experimental time). In the second set, the effect of intracaval U-74389G injection after 30 min of ischemia, followed by a longer reperfusion period of 120 min was determined (biopsies at 0, 15, 30 and 150 min experimental time). Liver malondialdehyde, hepatocyte vacuolation-degeneration, venous congestion, inflammatory cell infiltration, sinus congestion-dilation and Chiu score of intestinal damage were determined at up to 150 min of reperfusion. In the second set of experiments, the Chiu score of intestinal damage was improved by the administration of U-74389G (3.17±0.40 vs. 4.33±0.21; P=0.030). However, in the two sets of experiments, the liver inflammatory reaction was more pronounced in the U-74389G groups (P=0.017 for the first set, P=0.021 for the second set). No significant effect of U-74389G on any other parameters was detected. In conclusion, intestinal damage due to portal venous congestion and reflow appears to be mitigated by the lazaroid U-74389G; however, intracaval administration of U-74389G does not appear to exert any protective effects against liver I/R-induced inflammation.

Variation of the aryl substituent on the piperazine ring within the 4-(piperazin-1-yl)-2,6-di(pyrrolidin-1-yl)pyrimidine scaffold unveils potent, non-competitive inhibitors of the inflammatory caspases

The inflammatory caspases (caspase-1, -4 and -5) are potential therapeutic targets for autoimmune and inflammatory diseases due to their involvement in the immune response upon inflammasome formation. A series of small molecules based on the 4-(piperazin-1-yl)-2,6-di(pyrrolidin-1-yl)pyrimidine scaffold were synthesized with varying substituents on the piperazine ring. Several compounds were pan-selective inhibitors of the inflammatory caspases, caspase-1, -4 and -5, with the ethylbenzene derivative CK-1-41 displaying low nanomolar K_i values across this family of caspases. Three analogs were nearly 10 fold selective for caspase-5 over caspase-1 and -4. The compounds display non-competitive, time dependent inhibition profiles. To our knowledge, this series is the first example of small molecule inhibitors of all three inflammatory caspases.