STC1 promotes monosodium urate crystal-induced gouty inflammation via the cAMP-PKA-NF-κB/NLRP3 pathway in mice.

Gouty arthritis (GA) is driven by NLRP3 inflammasome-dependent pyroptosis. Stanniocalcin-1 (STC1) is a secreted glycoprotein implicated in inflammatory regulation, but its role in GA is unclear. This study examined whether STC1 promotes MSU-induced NLRP3 activation and pyroptosis via cAMP-PKA signalling and interaction with NOTCH1. MSU-induced GA was established in wild-type and STC1-knockout mice to assess joint swelling, histopathology, cytokines and NLRP3-pyroptosis markers. In vitro, J774A.1 cells were subjected to MSU stimulation with lentiviral STC1 knockdown and NOTCH1 overexpression. cAMP levels, ROS, mitochondrial membrane potential, NF-κB activation, NLRP3 components and pyroptosis were evaluated by ELISA, fluorescent probes, Western blotting, CCK-8 and caspase-1/PI flow cytometry, with KH7 and H89 used to inhibit cAMP and PKA. STC1-NOTCH1 interaction was analyzed by in silico prediction, co-immunoprecipitation and immunofluorescence. STC1 was upregulated in GA ankles, and STC1 deficiency reduced ankle swelling, tissue damage, neutrophilia, uric acid elevation and NLRP3-dependent pyroptosis. Gene Ontology analysis of STC1-related genes highlighted cAMP-mediated signalling and inflammatory responses, and protein-interaction prediction identified NOTCH1 as a putative STC1-binding partner. In J774A.1 cells, STC1 knockdown increased cell viability and reduced apoptosis and pyroptosis, while decreasing ROS, mitochondrial depolarisation, NF-κB activation, LDH release and expression of NLRP3, ASC, cleaved caspase-1, GSDMD-N, IL-1β and IL-18. STC1 knockdown elevated cAMP in vivo and in vitro, whereas the adenylate cyclase inhibitor KH7 or the PKA inhibitor H89 abolished these antioxidant and anti-pyroptotic effects. STC1 physically interacted and colocalised with NOTCH1, and NOTCH1 overexpression in STC1-silenced cells lowered cAMP, reactivated NF-κB/NLRP3 signalling and restored pyroptosis. In conclusion, STC1 cooperates with NOTCH1 to suppress cAMP-PKA signalling and thereby enhance NF-κB-driven NLRP3 inflammasome activation and pyroptosis in GA.