NLRP3 inflammasome inhibitor cucurbitacin B suppresses gout arthritis in mice

Gouty arthritis is a common inflammatory disease characterized by monosodium urate (MSU) crystal-induced nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome activation with upregulated caspase 1 protease and IL-1β in macrophages. Cucurbitacin B (CuB) is a tetracyclic triterpene that possesses a potential anti-inflammatory activity. However, the immunomodulatory and anti-inflammatory effects of CuB on gout have not been well characterized. Therefore, the purpose of the present study was to determine whether CuB exhibits anti-inflammatory effects on gout and to analyze the underlying molecular mechanism. We examined the effects of CuB on various stimuli-activated bone marrow-derived macrophages (BMDMs) and in a mouse model with MSU-induced acute gouty arthritis. Our results demonstrated that CuB effectively suppressed multiple stimuli-activated IL-1β secretion by interrupting NLRP3 inflammasome complex formation, inhibiting NLRP3 inflammasome activation and suppressing key enzymes of glycolysis in macrophages. Consistent with this, CuB pretreatment also ameliorated MSU-induced arthritis in vivo models of gout arthritis, manifested by reduced foot swelling and inflammatory cell infiltration. Taken together, our data provide the evidence that CuB is an NLRP3 inflammasome inhibitor with therapeutic potential for treating NLRP3 inflammasome-mediated diseases, especially gouty arthritis.