PLCd4 signaling-mediated PI4P synthesis drives macrophage NLRP3 inflammasome activation to promote heat stroke-induced tissue injury

Heat stroke causes life-threatening systemic inflammation and multiorgan injury, but the intracellular mechanisms that sustain inflammatory amplification after heat exposure remain unclear. Here, using heat stroke mouse models, genetic NLRP3 deletion, pharmacological inhibition, myeloid-specific NLRP3 deficiency, macrophage depletion, and heat-stressed macrophage systems, we show that tissue macrophage NLRP3 inflammasome activation is a central driver of interleukin-1β/interleukin-18 release, organ injury, and mortality. Mechanistically, heat stroke enhances phospholipase C delta 4 signaling, promotes diacylglycerol accumulation at trans-Golgi network/Golgi-associated membranes, recruits protein kinase D1, and increases phosphatidylinositol 4-kinase β-dependent phosphatidylinositol 4-phosphate production. This lipid remodeling supports NLRP3 recruitment, ASC speck formation, caspase-1 activation, and inflammatory cytokine release. Phospholipase C delta 4 knockdown preferentially suppresses NLRP3 activation induced by heat stroke, but not by canonical stimuli. These findings link heat stroke to membrane lipid remodeling and spatial inflammasome assembly, identifying a potential organ-protective pathway in heat stroke.