Normal CFTR Inhibits Epidermal Growth Factor Receptor-Dependent Pro-Inflammatory Chemokine Production in Human Airway Epithelial Cells

Abstract

Mutations in cystic fibrosis transmembrane conductance regulator (CFTR) protein cause cystic fibrosis, a disease characterized by exaggerated airway epithelial production of the neutrophil chemokine interleukin (IL)-8, which results in exuberant neutrophilic inflammation. Because activation of an epidermal growth factor receptor (EGFR) signaling cascade induces airway epithelial IL-8 production, we hypothesized that normal CFTR suppresses EGFR-dependent IL-8 production and that loss of CFTR at the surface exaggerates IL-8 production via activation of a pro-inflammatory EGFR cascade. We examined this hypothesis in human airway epithelial (NCI-H292) cells and in normal human bronchial epithelial (NHBE) cells containing normal CFTR treated with a CFTR-selective inhibitor (CFTR-172), and in human airway epithelial (IB3) cells containing mutant CFTR versus isogenic (C38) cells containing wild-type CFTR. In NCI-H292 cells, CFTR-172 induced IL-8 production EGFR-dependently. Pretreatment with an EGFR neutralizing antibody or the metalloprotease TACE inhibitor TAPI-1, or TACE siRNA knockdown prevented CFTR-172-induced EGFR phosphorylation (EGFR-P) and IL-8 production, implicating TACE-dependent EGFR pro-ligand cleavage in these responses. Pretreatment with neutralizing antibodies to IL-1R or to IL-1alpha, but not to IL-1beta, markedly suppressed CFTR-172-induced EGFR-P and IL-8 production, suggesting that binding of IL-1alpha to IL-1R stimulates a TACE-EGFR-IL-8 cascade. Similarly, in NHBE cells, CFTR-172 increased IL-8 production EGFR-, TACE-, and IL-1alpha/IL-1R-dependently. In IB3 cells, constitutive IL-8 production was markedly increased compared to C38 cells. EGFR-P was increased in IB3 cells compared to C38 cells, and exaggerated IL-8 production in the IB3 cells was EGFR-dependent. Activation of TACE and binding of IL-1alpha to IL-1R contributed to EGFR-P and IL-8 production in IB3 cells but not in C38 cells. Thus, we conclude that normal CFTR suppresses airway epithelial IL-8 production that occurs via a stimulatory EGFR cascade, and that loss of normal CFTR activity exaggerates IL-8 production via activation of a pro-inflammatory EGFR cascade.

Esculentin-1a-Derived Peptides Promote Clearance of Pseudomonas aeruginosa Internalized in Bronchial Cells of Cystic Fibrosis Patients and Lung Cell Migration: Biochemical Properties and a Plausible Mode of Action

“…This would impair the binding of ligands to EGFR with a resulting weaker EGFR activation (36). However, the discrepancy between the two peptides in the wound-healing activity may also be related to a difference in the binding affinity of the two AMPs to the target receptor (presumably EGFR or membrane-bound metalloproteases [42,66]). Furthermore, we cannot rule out the participation of alternative processes in controlling migration of bronchial cells.…”

“…Furthermore, the implication of epidermal growth factor receptor (EGFR) in peptide-induced cell migration was analyzed by pretreating cells for 30 min with 5 M tyrosine phosphorylation inhibitor tyrphostin (AG1478) (42).…”

“…The airways of healthy or CF human subjects express EGFR (42), which is involved in the repair of damaged airway epithelium (51). Hence, we examined whether the peptide-promoted cell migration was a process mediated by the EGFR signaling pathway.…”

Airway Epithelium and Mucous Secretion

“…It is known that activation of the EGFR is responsible for the production of IL-8, which is a potent neutrophil chemokine. 45 Kim and associates 46 recently hypothesized that normal CFTR sup- conspicuous. A correlation was found between the presence of bronchitis and the presence of submucosal gland hypertrophy in the central airways of smokers.…”

“…Because IL-8 production in airway epithelial cells depends on activation of EGFR, 45 Kim and coworkers hypothesized that CFTR normally suppresses EGFRdependent IL-8 production and that the loss of CFTR exaggerates EGFR-dependent IL-8 production via an exaggerated EGFR cascade. 46 In cultured airway epithelial cells containing CFTR, treatment with the CFTR(inh)-172 induced increased IL-8 production dependent on EGFR, which led to the production and release of IL-1α. The secreted IL-1α, bound to its receptor (IL-1R), caused EGFR activation and downstream exaggerated IL-8 production (in excess of constitutive IL-8 production).…”