NLRP3 inflammasome dependent loss of mitochondrial and cell membrane integrity in bone marrow derived macrophages (114.3)

Abstract

Abstract The NLRP3 inflammasome is a multiprotein complex that includes the adaptor protein ASC (apoptosis-associated speck-like protein containing a CARD), which binds with caspase-1 via CARD-CARD interactions and is involved with caspase-1 activation. Pore forming toxins, such as tetanolysin O (TLO), as well as the potassium ionophore nigericin, stimulate the NLRP3 inflammasome. We have observed that NLRP3 knockout macrophages are more resistant to the loss of membrane integrity compared to wild type macrophages exposed to nigericin or TLO, as assessed by a dye uptake assay. Furthermore, this NLRP3 dependent loss of membrane integrity corresponds to the loss of mitochondrial membrane integrity as demonstrated via live cell microscopy. The loss of mitochondrial membrane integrity, but not mitochondrial depolarization was found to be dependent on the presence of NLRP3. Furthermore, the loss of mitochondrial integrity and the loss of cell membrane integrity suggest a potential mechanistic pathway for the effects of NLRP3 inflammasome activation in BMDM. These results further our understanding of how NLRP3 functions in macrophages exposed to stressful stimuli such as bacterial toxins.