AIMS: The NLRP3 inflammasome is a multiprotein complex that protects hosts 
against a variety of pathogens. However, the molecular mechanisms of modulating 
NLRP3 inflammasome activation, especially at the priming step, are still poorly 
understood. This study was designed to elucidate the negative regulation of 
nuclear factor E2-related factor-2 (Nrf2) on the activation of NLRP3 
inflammasome.
RESULTS: We reported that Nrf2 activation inhibited NLRP3 expression, caspase-1 
cleavage, and subsequent IL-1β generation. Compared with normal cells, 
Nrf2-deficient cells showed upregulated cleaved caspase-1, which were attributed 
to the increased transcription of NLRP3 caused by excess reactive oxygen species 
(ROS). Furthermore, priming of the NLRP3 inflammasome was sensitive to the 
exogenous ROS levels induced by H2O2 or rotenone. Combined with adenosine 
triphosphate, rotenone triggered higher activity of the NLRP3 inflammasome 
compared with lipopolysaccharide, suggesting that ROS promoted the priming step. 
In addition, Nrf2-induced NQO1 was involved in the inhibition of the NLRP3 
inflammasome. In an in vivo alum-induced peritonitis mouse model, Nrf2 
activation suppressed typical IL-1 signaling-dependent inflammation, whereas 
Nrf2-/- mice exhibited a significant increase in the recruitment of immune cell 
and the generation of IL-1β compared with wild-type mice.
INNOVATION: We elucidated the effects and possible mechanisms of Nrf2 
activation-induced NQO1 expression on NLRP3 inflammasome inactivation and 
established a novel regulatory role of the Nrf2 pathway in ROS-induced NLRP3 
priming.
CONCLUSIONS: We demonstrated Nrf2 negatively regulating NLRP3 inflammasome 
activity by inhibiting the priming step and suggested that Nrf2 could be a 
potential target for some uncontrolled inflammasome activation-associated 
diseases. Antioxid. Redox Signal. 26, 28-43.