Discovery of Potent, Specific, and Orally Available NLRP3 Inflammasome Inhibitors Based on Pyridazine Scaffolds for the Treatment of Septic Shock and Peritonitis

The NLRP3 inflammasome is a multiprotein complex that
is a component
of the innate immune system, involved in the production of pro-inflammatory
cytokines. Its abnormal activation is associated with many inflammatory
diseases. In this study, we designed and synthesized a series of NLRP3
inflammasome inhibitors based on pyridazine scaffolds. Among them, P33 exhibited significant inhibitory effects against nigericin-induced
IL-1β release in THP-1 cells, BMDMs, and PBMCs, with IC50 values of 2.7, 15.3, and 2.9 nM, respectively. Mechanism
studies indicated that P33 directly binds to NLRP3 protein
(KD = 17.5 nM), inhibiting NLRP3 inflammasome
activation and pyroptosis by suppressing ASC oligomerization during
NLRP3 assembly. Additionally, P33 displayed excellent
pharmacokinetic properties, with an oral bioavailability of 62%. In vivo efficacy studies revealed that P33 significantly
ameliorated LPS-induced septic shock and MSU crystal-induced peritonitis
in mice. These results indicate that P33 has great potential
for further development as a candidate for treating NLRP3 inflammasome-mediated
diseases.