Cigarette smoke extract induces pyroptosis in human bronchial epithelial cells through the ROS/NLRP3/caspase-1 pathway

AIMS: Pyroptosis and inflammation are involved in the development of chronic obstructive pulmonary disease (COPD). However, the cigarette smoke-mediated mechanism of COPD remains unclear. In this study, we aimed to investigate the role of nucleotide-binding domain-like receptor protein-3 (NLRP3) inflammasome-mediated pyroptosis in the death of human bronchial epithelial (HBE) cells after cigarette smoke extract (CSE) exposure. MAIN METHODS: The protein level of NLRP3 in lung tissue was measured after cigarette smoke exposure in vivo. In vitro, HBE cells were treated with CSE. Subsequently, the activity of caspase-1, lactate dehydrogenase (LDH) release, release of interleukin (IL)-1β and NLRP3 expression levels were measured. The involvement of reactive oxygen species (ROS) was also explored. KEY FINDINGS: After exposure to CSE, increased release of LDH, the transcriptional and translational upregulation of NLRP3, the caspase-1 activity levels, and enhanced IL-1β and IL-18 release were observed in 16HBE cells. In addition, NLRP3 was required to activate the caspase-1. Our results suggested that pre-stimulated of 16HBE with a caspase-1 inhibitor, or using NLRP3 siRNA to silence NLRP3 expression, also caused the decrease of IL-1β release and pyroptosis. SIGNIFICANCES: CSE induced inflammation and contributed to pyroptosis through the ROS/NLRP3/caspase-1 pathway in 16HBE cells. The NLRP3 inflammasome participates in CSE-induced HBE cell damage and pyroptosis, which could provide new insights into COPD.