Abstract: Objective To investigate the mechanism of cigarette smoke extract (CSE) inducing apoptosis of pulmonary artery endothelial cells (HPAECs), especially focus on the role of NLRP3(NLR family pyrin domain protein 3) inflammasome. Methods After transfection with NLRP3 siRNA and NC siRNA, HPAECs from experimental group and control group were stimulated by 10% CSE for 12 h, annexin V/PI flow method was used to detect the apoptosis of the two groups of cells before and after CSE stimulation. Cultured HPAECs were further divided into four groups:control group, CSE group (10% CSE solution was added), NAC+CSE group (10 mmol/L NAC pretreatment for 1 h and then 10% CSE culture solution) and NAC group (10 mmol/L NAC treatment for 1 h). After 12 h culture, intracellular reactive oxygen species(ROS) were detected by DCFH-DA fluorescent probe. The expression of NLRP3 and caspase-1 was determined by Western blot. Results After CSE stimulation, the survival rate of HPAECs in siNC group decreased, and the apoptosis was significantly increased as compared with that before CSE stimulation (P＜0.05). After CSE stimulation, the apoptosis rate of siNLRP3 group decreased compared with that after the same CSE stimulation in siNC group (P＜0.05).The intracellular ROS level in the CSE group was significantly increased as compared with that in the control group, which in the NAC+CSE group was decreased compared with that in the CSE group (P＜0.05). In the CSE group, NLRP3 and caspase-1 were significantly increased compared with the control group, while the expression of NLRP3 and caspase-1 in NAC+CSE group was lower than that in CSE group (P＜0.05). Conclusions CSE could induce apoptosis of HPAECs accompanied by increased NLRP3 inflammatory corpuscle expression. Silencing of NLRP3 protein expression can inhibit the apoptotic effect of CSE on HPAEC.

Key words: NLRP3, inflammasome, cigarette smoke extract, pulmonary artery endothelial cells, apoptosis