<p>Rheumatoid arthritis (RA) is a chronic autoimmune disorder marked by synovial inflammation and joint damage, with fibroblast-like synoviocytes (FLS) acting as key drivers of RA pathogenesis. Pyroptosis, a form of inflammatory programmed cell death, contributes to RA synovial pathology. Although aquaporin-1 (AQP1) has been implicated in RA progression, its role in pyroptosis and the underlying mechanisms remain unclear. Through bioinformatics analyses of multiple transcriptomic datasets and experimental validation in adjuvant-induced arthritis (AIA) rats, we identified AQP1 as a pyroptosis-related gene elevated in RA synovium. Functional assays revealed that AQP1 promotes pyroptotic cell death and induces the release of IL-1β and IL-18 in RA-FLS. Pathway enrichment analyses and experimental evidence identified β-catenin as a crucial downstream mediator of AQP1 in regulating pyroptosis in RA-FLS. Mechanistically, AQP1 binds to β-catenin via its C-terminal domain, disrupting the interaction between β-catenin and GSK-3β, thereby preventing GSK-3β-mediated phosphorylation and degradation of β-catenin. As a result, cytoplasmic β-catenin is stabilized and accumulates, which then interacts with NLRP3 to facilitate NLRP3-ASC complex formation and NLRP3 inflammasome assembly, thereby activating caspase-1 and triggering pyroptosis in RA-FLS. In AIA rats, intra-articular injection of adeno-associated virus to knock down AQP1 relieved paw swelling, synovial lesions, cartilage damage, and systemic inflammation, accompanied by reduced expression of β-catenin and pyroptosis-related markers within the synovium. Collectively, this study demonstrates a novel AQP1/β-catenin/NLRP3 axis driving pyroptosis in RA-FLS and highlights targeting AQP1-induced pyroptosis as a potential strategy for RA treatment.</p>