IL-1β hyperproduction is mediated by NLRP3 through a RIPK3-independent mechanism. (A) Control and XIAP-KO THP-1 cells were stimulated with LPS under standard (10% FCS) and serum starvation (1% FCS) conditions for 4 hours, followed by harvesting for RNA isolation and quantitative real-time PCR for IL-1β transcript levels. Results are normalized to GAPDH transcript levels. (B) Control and XIAP-knockout THP-1 cells were stimulated as indicated in panel A followed by protein extraction for western blotting using anti-IL-1β. Anti-GAPDH was used as loading control. (C) XIAP-KO THP-1 cells were stimulated as indicated under standard (10% FCS) or serum starvation (1% FCS) conditions with or without the addition of NLRP3 inhibitor MCC950. Supernatants were harvested at 4 hours for IL-1β measurement using ELISA. (D) XIAP-KO THP-1 cells were stimulated as indicated under standard (10% FCS) or serum starvation (1% FCS) conditions with or without the addition of RIPK3 inhibitor GSK872. Supernatants were harvested at 4 hours for IL-1β measurements by ELISA. All results are representative of 3 independent experiments. Graphs indicate the mean with standard deviation.