Mitochondrial calcium uptake drives organelle remodeling to promote inflammasome-dependent cytokine release.

Mitochondrial Ca2+ uptake shapes cellular signaling by modulating metabolism, cell death and cytosolic Ca2+ dynamics, yet its pathological and therapeutic relevance remains undefined. Here, we show that Ca2+ entry through the mitochondrial Ca2+ uniporter (MCU) is required for mitochondrial fragmentation and subsequent NLRP3 inflammasome-mediated IL-1β release in lipopolysaccharide-primed, stimulated macrophages. This fragmentation occurs independently of the mitochondrial permeability transition pore but depends on activation of the organelle fission machinery. In an inflammatory disease model, MCU deficiency attenuated IL-1β secretion and reduced monosodium urate (MSU) crystal-induced joint inflammation in vivo. Collectively, our findings establish mitochondrial Ca2+ uptake as a key upstream signal that promotes organelle fragmentation to license inflammasome activation, positioning MCU as a potential therapeutic target in inflammatory diseases.