Nitrosonisoldipine is a selective inhibitor of inflammatory caspases and protects against pyroptosis and related septic shock

Pyroptosis is a type of acute cell death that mainly occurs in immune cells. It is characterized with robust release of inflammatory cytokines and has emerged to play a critical role in the pathogenesis of sepsis-associated immune disorders. In this study, we screened for pyroptotic inhibitors with the ultimate goal to benefit sepsis treatments. Accidentally, we identified that nitrosonisoldipine (NTS), a photodegradation product of Calcium Channel Inhibitor nisoldipine, inhibits noncanonical Pyroptosis. Using murine immortalized BM-derived macrophage and human THP-1 cell line, we further discovered that NTS not only inhibits noncanonical Pyroptosis mediated by caspase-11 or caspase-4 but also canonical Pyroptosis mediated by Caspase-1. Mechanistically, NTS directly inhibits the Enzyme activities of these inflammatory caspases, and these inhibitory effects persist despite extensive washout of the drug. By contrast, Apoptosis mediated by Caspase-3/-7 was not affected by NTS. Mice pretreated with NTS intraperitoneally displayed improved survival rate and extended survival time in LPS- and polymicrobe-induced septic models, respectively. In conclusion, NTS is a selective inhibitor of inflammatory caspases that blocks both the noncanonical and canonical pyroptotic pathways. It is safe for intraperitoneal administration and might be used as a prototype to develop drugs for sepsis treatments.