Role Of NLRP3Inflammasome In Endothelial Cells Inflammation Induced By High Uric Acid

Objective: High concentration uric acid (HUA) is an independent risk factor forcardiovascular disease and chronic kidney diseases. Recent studies suggest thatcrystals of monosodium urate (MSU) activate NLRP3inflammasome in gout.Inflammasome triggers activation of caspase-1and the release of IL-1β and IL-18serving as an intracellular machinery to initiate inflammatory response to variousdanger signals. The present study tested whether NLRP3inflammasome triggersendothelial cells inflammatory response to HUA.Methods: Mouse were divided into two groups, the model group mouse wereinjected intraperitoneal uric acid and oxonic acid. The expression of NLRP3,caspase-1, NLRP1were detected by Western Blot and fluorescence microscopy.Level of serum IL-1β and IL-18were detected by ELISA. Human umbilical veinendothelia cells (EAHY) were cultured in medial with or without HUA, NLRP3,caspase-1, NLRP1expression and cell supernatant IL-1β and IL-18concentrationwere detected by Western Blot, fluorescence microscopy or ELISA. Then the IL-1βand IL-18level of cell supernatant were assessed by inhibiting NLRP3and caspase-1using siRNA or caspase-1inhibitor.Results: NLRP3inflammasome components were increasing expressed in mouseintraperitoneal injected uric acid and oxonic acid and in cultured human umbilicalvein endothelia cells (EAHY), including NLRP3and caspase-1, as shown byfluorescence microscopy and Western Blot. But the change of NLRP1was notdetected. Correspondingly, HUA significantly increased the concentration of IL-1βand IL-18in serum and cell supernatant. The increased concentration of IL-1β and IL-18were abolished by inhibiting NLRP3or caspase-1using NLRP3siRNA andcaspase-1inhibition Z-VAD-fmk in vitro or in vivo.Conclusion: High concentration uric acid (HUA) lead to the activition of NLRP3inflammasome but not NLRP1inflammasome and stimulated the secretion ofcytokines IL-1β, IL-18. The secretion of IL-1β and IL-18induced by HUA wasdecreased by inhibiting the expression of NLRP3or caspase-1. The formation andactivation of NLRP3inflammasome by HUA may be an important initiatingmechanism to turn on the endothelial inflammatory response.