Effects of Gentiopicroside on activation of NLRP3 inflammasome in acute gouty arthritis mice induced by MSU

Acute gouty arthritis is a self-limiting inflammatory disease resulting from the deposition of monosodium urate (MSU) crystals. It has been shown that Gentiopicroside (GPS) possesses anti-inflammatory and analgesic functions. The aim of this study was to parse out whether GPS has an effect on acute gouty arthritis. We established an acute gouty arthritis model by the injection of MSU into the paw, and found that GPS relieves MSU-induced mechanical, thermal hyperalgesia, and paw swelling. Furthermore, GPS down-regulated the release of pro-inflammatory cytokines in paw tissues, including IL-1β, IL-6, IL-18, and TNF-α. The results of H&E staining and MPO activity measurement showed that GPS inhibits neutrophil infiltration. And the over-expressions of NOD-like receptor protein 3 (NLRP3), apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), and Caspase-1 induced by MSU were inhibited by treatment with GPS. These results revealed that GPS can treat acute gouty arthritis based on anti-inflammatory and analgesic properties in vivo, which might be ascribed to the inhibition on NLRP3 inflammasome. Furthermore, we performed in vitro study to confirm the results of in vivo study. Consistently, the results proved that GPS could inhibit the activation of NLRP3 inflammasome in RAW264.7 macrophages stimulated by LPS-MSU. In conclusion, this study provides an experimental basis for the application of GPS and expands the potential value of GPS in the therapy of acute gouty arthritis.