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.