Fig. 7.

Neutrophil elastase (NE) in neutrophil extracellular traps (NETs) contributes to cytokine changes in human bronchial epithelial cells (HBEs). A: neutrophil elastase activity was measured in NETs in the absence and presence of HBE, both with and without the NE inhibitor sivelestat 100 μg/mL for 18 h. B–E: HBEs grown at air-liquid interface were exposed to PBS, NETs, or NETs + 100 μg/mL sivelestat for 18 h. Cytokine concentrations in apical supernatant of HBEs were measured by Luminex, and IL-8 concentration was confirmed by ELISA and analyzed by Student’s t test. F: RNA expression of cytokine genes was measured by RT-PCR, and fold changes were calculated relative to HBEs exposed to PBS and analyzed by one-way ANOVA. (HBE donors = 2, NET donors = 2.) *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.