Daphnetin alleviates inflammation and promotes autophagy via the AMPK/mTOR pathway in gouty arthritis

Gouty arthritis (GA) is an inflammatory disease resulting from monosodium urate (MSU) crystal deposition in joints and surrounding tissues. Daphnetin (DAP) is a coumarin derivative with potent anti-inflammatory activity. Nonetheless, whether DAP can protect against MSU-induced acute GA remains unclarified. In this study, C57BL/6 mice were injected intra-articularly with MSU crystal suspension to induce acute GA. THP-1 cells were stimulated with MSU to mimic the microenvironment of GA in vitro. Hematoxylin-eosin staining was conducted to observe the pathological changes in mouse synovial tissues. ELISA and RT-qPCR were employed for inflammatory cytokine level determination. Immunofluorescence staining was performed to estimate LC3 expression in THP-1 cells. Western blotting was used for protein expression analysis. The results showed that DAP pretreatment mitigated MSU-elicited ankle joint swelling and synovial damage in mice. Moreover, DAP hindered proinflammatory factor expression and promoted autophagy in MSU-stimulated GA mice and THP-1 cells. Mechanistically, DAP induced AMPK activation and mTOR inactivation. Blocking AMPK signaling counteracted DAP-mediated effects on inflammation and autophagy in MSU-stimulated THP-1 cells. In conclusion, DAP prevents MSU-elicited GA by alleviating inflammation and enhancing autophagy via AMPK/mTOR signaling transduction.