Apilimod activates the NLRP3 inflammasome through lysosome-mediated mitochondrial damage

NLRP3 is a key innate immune sensor that responds to various signals and forms the inflammasome complex, driving IL-1β secretion and pyroptosis. Lysosomal damage has been implicated in NLRP3 inflammasome activation in response to crystals or particulates, but the underlying mechanism remains unclear. Through small molecule library screening, we identified apilimod, a lysosomal disruptor, as a selective and potent NLRP3 agonist. Apilimod effectively promotes NLRP3 inflammasome activation, IL-1β secretion, and pyroptosis.

Mechanistically, apilimod activates NLRP3 independent of potassium efflux and direct binding. Instead, apilimod induces mitochondrial damage and lysosomal dysfunction. Further investigation revealed that apilimod triggers a TRPML1-dependent calcium flux in lysosomes, which leads to mitochondrial damage and subsequent NLRP3 inflammasome activation.

Our findings uncover the pro-inflammasome activity of apilimod and the calcium-dependent lysosome-mediated mechanism underlying NLRP3 inflammasome activation.