MCC950/CRID3 potently targets the NACHT domain of wildtype NLRP3 but not disease-associated mutants for inflammasome inhibition
The NLRP3 inflammasome drives pathological inflammation in a suite of autoimmune, metabolic, malignant and neurodegenerative diseases. Additionally, NLRP3 gain-of-function point mutations cause systemic periodic fever syndromes that are collectively known as cryopyrin-associated periodic syndromes (CAPS). There is significant interest in the discovery and development of diarylsulfonylurea Cytokine Release Inhibitory Drugs (CRIDs) such as MCC950/CRID3, a potent and selective inhibitor of the NLRP3 inflammasome, for the treatment of CAPS and other diseases. However, drug discovery efforts have been constrained by the lack of insight in the molecular target and mechanism by which these CRIDs inhibit the NLRP3 inflammasome. Here, we show that the NACHT domain of NLRP3 is the molecular target of diarylsulfonylurea inhibitors. Interestingly, we find photoaffinity labelling of the NACHT domain requires an intact (d)ATP-binding pocket and is substantially reduced for most CAPS-associated NLRP3 mutants. In concordance, MCC950/CRID3 failed to inhibit NLRP3- driven inflammatory pathology in two mouse models of CAPS. Moreover, it abolished circulating levels of interleukin (IL)-1{beta} and IL-18 in LPS-challenged wildtype mice but not in Nlrp3L351P knock-in mice and ex vivo-stimulated mutant macrophages. These results identify wildtype NLRP3 as the molecular target of MCC950/CRID3, and show that CAPS-related NLRP3 mutants escape efficient MCC950/CRID3 inhibition. Collectively, this work suggests that MCC950/CRID3-based therapies may effectively treat inflammation driven by wildtype NLRP3, but not CAPS-associated mutants.