Cigarette Smoke Extract and Lipopolysaccharide Induce Pyroptosis in Pulmonary Microvascular Endothelial Cells of Rats.

Abstract

We studied the effect of cigarette smoke extract (CSE), LPS, or their combination on the activity and pyroptosis of pulmonary microvascular endothelial cells (PMVEC) in rats. PMVEC were cultured without treatment, with CSE in different concentrations (1-25%), with 20 ng/ml LPS, or with 20% CSE+20 ng/ml LPS. Cell viability was determined using the CCK8 kit, apoptosis was evaluated by flow cytometry, and cell morphology was evaluated using light microscopy. The content of IL-1β and IL-18 was measured by ELISA. CSE decreased cell viability in a dose-dependent manner. The morphology of cells in the CSE+LPS group showed the most significant cytomorphological changes and the highest pyroptosis rate. Flow cytometry showed that the apoptosis rates in the CSE and LPS groups were higher than in the control group, but the highest rate of apoptosis was revealed in the CSE+LPS group (p<0.01). The levels of IL-18 and IL-1β in the cell supernatant of the CSE, LPS, and CSE+LPS groups were significantly (p<0.01) increased in comparison with the control. These levels in the CSE+LPS group were higher (p<0.01) than in other groups. There were no differences between the CSE and LPS groups. Thus, the effect of CSE on cell viability is dose-dependent. Combined treatment with CSE+LPS can induce cell pyroptosis and increase the levels of inflammatory cytokines in PMVEC. These observations demonstrated that pyroptosis caused by CSE and LPS can play an important role in pulmonary vascular remodeling.