In vitro activity: MCC950 sodium, the sodium salt of MCC950 (also known as MCC-950, CP-456773 or CRID3), is a potent, selective, small-molecule inhibitor of NLRP3 that has the potential for the treatment of inflammatory diseases and diabetic encephalopathy (DEP). MCC950 blocked canonical and noncanonical NLRP3 activation at nanomolar concentrations. MCC950 specifically inhibited activation of NLRP3 but not the AIM2, NLRC4 or NLRP1 inflammasomes. MCC950 reduced interleukin-1β (IL-1β) production in vivo and attenuated the severity of experimental autoimmune encephalomyelitis (EAE), a disease model of multiple sclerosis. Furthermore, MCC950 treatment rescued neonatal lethality in a mouse model of CAPS and was active in ex vivo samples from individuals with Muckle-Wells syndrome. MCC950 is thus a potential therapeutic for NLRP3-associated syndromes, including autoinflammatory and autoimmune diseases, and a tool for further study of the NLRP3 inflammasome in human health and disease. In addition, inhibiting the NLRP3 Inflammasome sctivation with MCC950 may ameliorate diabetic encephalopathy (DEP) in db/db mice.

Kinase Assay: MCC950 inhibits canonical and noncanonical NLRP3 activation in BMDM and HMDM cells at IC50 of 7.5 and 8.1nM. MCC950 specifically inhibits activation of NLRP3 but not the AIM2, NLRC4 or NLRP1 inflammasomes. MCC950 also dose dependently inhibit IL-1β but not TNF-α secretion.MCC950 specifically blocks caspase-11-directed NLRP3 activation and IL-1β secretion upon stimulation of the non-canonical pathway. NLRC4-stimulated IL-1β and TNF-α secretion (as activated by Salmonella typhimurium) are not inhibited by MCC950 even at a concentration of 10 μM. MCC950 does not inhibit caspase-1 activation or IL-1β processing in response to S. typhimurium. The expression of pro-caspase-1 and pro-IL-1β in cell lysates is not substantially affected by MCC950 treatment

Cell Assay: BMDM are seeded at 5×105/mL or 1×106/mL, HMDM at 5×105/mL and PBMC at 2×106/mL or 5×106/mL in 96 well plates. The following day the overnight medium is replaced and cells are stimulated with 10 ng/mL LPS from Escherichia coli serotype EH100 (ra) TLRgrad for 3 h. Medium is removed and replaced with serum free medium (SFM) containing DMSO (1:1,000), MCC950 (0.001-10 μM), glyburide (200 μM), Parthenolide (10 μM) or Bayer cysteinyl leukotriene receptor antagonist 1-(5-carboxy-2{3-[4-(3-cyclohexylpropoxy)phenyl]propoxy}benzoyl)piperidine-4-carboxylic acid (40 μM) for 30 min. Cells are then stimulated with inflammasome activators: 5 mM adenosine 5’-triphosphate disodium salt hydrate (ATP) (1 h), 1 μg/mL Poly(deoxyadenylic-thymidylic) acid sodium salt (Poly dA:dT) transfected with Lipofectamine 200 (3-4 h), 200 μg/mL MSU (overnight) and 10 μM nigericin (1 h) or S. typhimurium UK-1 strain. Cells are also stimulated with 25 μg/mL Polyadenylic-polyuridylic acid (4 h). For non-canonical inflammasome activation cells are primed with 100 ng/mL Pam3CSK4 for 4 h, medium is removed and replaced with SFM containing DMSO or MCC950 and 2 μg/mL LPS is transfected using 0.25% FuGENE for 16 h. Supernatants are removed and analysed using ELISA kits. LDH release is measured using the CytoTox96 non-radioactive cytotoxicity assay.