The NLRP3 inflammasome is a critical component of the innate immune response to sterile inflammation. Its regulation involves a priming step, required for up-regulation of inflammasome protagonists and an activation step leading to NLRP3 inflammasome complex assembly, which triggers caspase-1 activity. The IkK8 kinase regulates canonical NF-kappa B, a key pathway involved in transcriptional priming. We found that IkK8 also regulates the activation and function of the NLRP3 inflammasome beyond the priming step. Two unrelated I kappa K beta inhibitors, AFN700 and TPCA-1, when applied after priming, fully blocked IL-beta secretion triggered by nigericin in THP-1 cells. Both inhibitors prevented neither inflammasome assembly, as monitored by measuring the formation of ASC specks, nor the generation of caspase-1 p20, a hallmark of caspase-1 activity, but they impaired the initial cleavage and activation of procaspase-1. These data thus indicate that IkK8 activity is required for efficient activation of NLRP3, suggesting that IkK8 may fulfill a dual role in coupling priming and activation of the NLRP3 inflammasome. (C) 2021 Elsevier Inc. All rights reserved.