Trillin alleviates rheumatoid arthritis by inhibiting TXNIP-mediated mitochondrial damage and NLRP3-dependent pyroptosis.

Macrophage pyroptosis in the synovial tissue of patients with rheumatoid arthritis (RA) releases large amounts of inflammatory cytokines, which further exacerbate the pathological progression of RA. Trillin, a natural steroidal saponin in Trillium tschonoskii Maxim and other medicinal plants, exhibits potent antioxidant and anti-inflammatory activities; however, its activity and mechanism of action in the treatment of RA remain unclear. To investigate the therapeutic effects of Trillin on RA and elucidate its underlying mechanism, we established in vitro macrophage pyroptosis models using Nigericin stimulation. Live cell imaging results indicate that Trillin significantly alleviated macrophage pyroptosis. Consistently, Trillin downregulated the protein expression levels of NOD-like receptor family pyrin domain-containing 3 (NLRP3), cleaved cysteine-dependent aspartate-directed protease-1 (caspase-1), and cleaved N-terminal Gasdermin D (GSDMD-N); and suppressed the secretion of the inflammatory cytokines interleukin-1β (IL-1β) and interleukin-18 (IL-18). In a collagen-induced arthritis (CIA) mouse model, Trillin effectively ameliorated joint inflammation, inhibited macrophage pyroptosis in articular tissues, and prevented disease-related weight loss. Transcriptomic profiling analysis verified that Trillin suppressed the NOD-like and Toll-like receptor signaling pathways, with the oxidative stress mediator TXNIP selectively regulated by Trillin but not methotrexate. Mechanistically, Trillin alleviated macrophage pyroptosis by suppressing Thioredoxin-interacting protein (TXNIP) expression and cytoplasmic translocation. Consistently, TXNIP knockdown delayed the disease onset and reduced macrophage pyroptosis in CIA mice. Collectively, these results indicate that Trillin effectively alleviates the pathological progression of RA by targeting TXNIP to inhibit NLRP3/GSDMD-mediated macrophage pyroptosis, suggesting that Trillin may serve as a potential candidate drug for the treatment of RA.