Kinetics of NLRP3 inflammasome independent and dependent mitochondrial damage during inflammasome activation (P1276)

Abstract The NLRP3 inflammasome is a protein complex that plays a central role in innate immunity and is involved with caspase-1 activation. In murine bone marrow derived macrophages (BMDM), NLRP3 inflammasome activation can lead to the processing and secretion of IL-1 beta, as well as pyroptotic cell death. Pore forming toxins, such as tetanolysin O (TLO), as well as the potassium ionophore nigericin, stimulate the NLRP3 inflammasome. In response to treatment with nigericin, we have observed that mitochondrial depolarization occurs independent of the presence of the NLRP3 inflammasome, however the loss of mitochondrial membrane integrity is NLRP3 dependent. This loss of mitochondrial integrity is preceded by NLRP3 dependent lysosomal membrane permeability. Hence, we have shown kinetically that NLRP3 inflammasome independent damage to the mitochondria precedes NLRP3 inflammasome dependent organelle damage and eventual cell death. The kinetic information provided via these data suggests a multi-step process involving both NLRP3 dependent and independent events during inflammasome activation.