Inhibition of NLRP3 oligomerization (active conformation) mediated by RACK1 ameliorates acute respiratory distress syndrome

Aberrant activation of the NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasome contributes to the pathogenesis of fatal and perplexing pulmonary diseases. Although pharmacologically inhibiting NLRP3 inflammasome brings potent therapeutic effects in several clinical trials and preclinical models, the molecular chaperones and transition detail in the formation of active oligomer from an auto-suppressed state remain controversial. Here, we showed that sesquiterpene bigelovin inhibited NLRP3 inflammasome activation and release of the downstreaming pro-inflammatory cytokines by canonical, noncanonical, and alternative pathways at nanomolar ranges. Chemoproteomic target identification disclosed that bigelovin covalently bound to the cysteine 168 of RACK1 and blocked the interaction between RACK1 and NLRP3 monomer, thereby interfering NLRP3 inflammasome oligomerization in vitro and in vivo . Treatment by bigelovin significantly alleviated the severity of NLRP3-related pulmonary disorders in murine models, such as LPS-induced ARDS and silicosis. These results consolidated the intricate role of RACK1 in transiting the NLRP3 state and provided a new anti-inflammatory lead and therapy for NLRP3-driven diseases.