CHAC1 Is Differentially Expressed in Normal and Cystic Fibrosis Bronchial Epithelial Cells and Regulates the Inflammatory Response Induced by Pseudomonas aeruginosa

Perra, Léa; Balloy, Viviane; Foussignière, Tobias; Moissenet, Didier; Petat, Hortense; Mungrue, Imran N.; Touqui, Lhousseine; Corvol, Harriet; Chignard, Michel; Guillot, Loic

To determine whether regulation of these inflammatory parameters involved NF-κB, we studied its phosphorylation by western blot in NCI-H292 cells. We observed that LPS induced a significant increase in NF-κB p65 phosphorylation in CHAC1-knockdown cells after 1 h of stimulation ( Figure 6A ). To confirm these data, we used A549-NF-κB luciferase cells. As in NCI-H292 cells, 60% inhibition of CHAC1 mRNA expression was observed after siRNA transfection (data not shown). Similar to NCI-H292 cells, we observed that 1 µg/mL LPS, 50 ng/mL flagellin, and the combination of both (LPS+flagellin) induced a significant increase in IL-8 secretion when A549 cells were transfected with CHAC1 siRNA compared with that in cells transfected with siRNA control (Figure 6B) . Additionally, as expected, we observed that 1 µg/mL LPS, 50 ng/mL flagellin, and the combination of both (LPS+flagellin) induced significant increases in NF-κB activity (Figure 6C ). Under these experimental conditions, when we decreased CHAC1 mRNA expression, we observed an even greater increase in NF-κB activity when cells were stimulated with LPS and/or flagellin ( Figure 6C) . IL-6 and CCL-2 were not detectable by ELISA (data not shown).