YDZG inhibits NLRP3 inflammasome activation.
The NLRP3 inflammasome is important for macrophage activation and the formation of the inflammasome complex during inflammatory process (Elliott & Sutterwala, 2015). In addition, IL-1β is an important pro-inflammatory cytokine and must be cleaved from its inactive form (pro-IL-1β) to the mature form by caspase 1 (He et al., 2016). To test whether YDZG can block NLRP3 activation, the impact of YDZG on NLRP3 inflammasome complex formation, caspase-1 activation, and IL-1β secretion was examined. YDZG (40 µM) significantly blocked the formation of the NLRP3 inflammasome induced by LPS and ATP (Figure 1B) and showed no significant cytotoxicity (Figure S1). Immunofluorescence staining results revealed that YDZG decreased caspase-1 p20 activation (Figure 1C), resulting in the decrease of mature IL-1β and cleaved caspase-1 release into supernatants (Figures 1D-E). Corresponding with IL-1β release, YDZG suppressed LPS- plus ATP-induced IL-1β gene expression (Figure 1F). In summary, these results suggested that YDZG blocked NLRP3 inflammasome. The mechanism of how YDZG blocks NLRP3 inflammasome activation was then studied.