Ponicidin Inhibits NLRP3 Inflammasome Activation via Alleviating Mitochondrial Damage in LPS-Primed Macrophages

The NLRP3 inflammasome is a cytosolic pattern-recognition complex that senses sterile and infectious insults and drives innate immune responses. Herein, we identify ponicidin (PON), a natural diterpenoid isolated from Rabdosia rubescens, as an inhibitor of NLRP3 inflammasome activation. In LPS-primed macrophages, PON suppressed IL-1β secretion by inhibiting caspase-1 activation and attenuated nigericin- or ATP-induced pyroptosis, as indicated by reduced LDH release and GSDMD cleavage. Meanwhile, AIM2 inflammasome-mediated IL-1β production was not affected by PON. Mechanistically, PON inhibited ASC oligomerization and speck formation, critical steps in NLRP3 inflammasome assembly. It could reduce mitochondria-derived danger signals related to NLRP3 activation, such as mtROS, mtDNA and ox-mtDNA, without affecting ion fluxes (e.g., K+, Ca2+, Cl−). Consistently, PON preserved the mitochondrial membrane potential and intracellular ATP levels, indicating comprehensive protection of mitochondrial function. In vivo, PON markedly reduced IL-1β levels in peritoneal lavage fluid of MSU-induced peritonitis mice and lowered serum IL-1β, TNF-α, and MCP-1 levels in endotoxemia mice. Collectively, PON alleviates mitochondrial dysfunction to prevent ASC oligomerization and NLRP3 inflammasome assembly, thereby reducing the cleavage of pro-IL-1β and GSDMD. Our findings suggest that PON may be a potential candidate for treating NLRP3 inflammasomopathies.