Tetrachlorobenzoquinone Stimulates NLRP3 Inflammasome-Mediated Post-Translational Activation and Secretion of IL-1β in the HUVEC Endothelial Cell Line

Our previous studies suggested that tetrachlorobenzoquinone (TCBQ) elicits pro-inflammatory activities; however, the mechanism of its toxicity toward vascular endothelial cell has not been characterized. Although TCBQ has been shown to stimulate interleukin-1 beta (IL-1β) expression, it is unknown whether TCBQ regulates post-translational IL-1β activation. Using human umbilical vein endothelial cells, we discovered that TCBQ not only promotes the expression of NOD-like receptor family, pyrin domain-containing protein 3 (NLRP3) components [composed of NLRP3, adaptor molecule apoptosis-associated speck like protein containing a caspase activation and recruitment domain (ASC), and pro-caspase 1] but also participates in priming the NLRP3 inflammasome. Activation of the NLRP3 inflammasome results in the maturation and release of IL-1β. Further experiments showed that K+ efflux, reactive oxygen species (ROS) production, and mitochondrial DNA damage may be involved in NLRP3 inflammasome activation mediated by TCBQ. Moreover, TCBQ downregulates the ubiquitination of NLRP3, further facilitating the activation of the NLRP3 inflammasome. These results suggest that the NLRP3/IL-1β signaling pathway plays an important role in TCBQ-induced endothelial cell pro-inflammatory responses, which may point to potential therapeutic approaches against TCBQ-mediated toxicity.