IL-13 and Epidermal Growth Factor Receptor Have Critical but Distinct Roles in Epithelial Cell Mucin Production

Abstract

Overproduction of mucus is a central feature of asthma. The cytokine, IL-13, epidermal growth factor receptor (EGFR), and transcription factor, FOXA2, have each been implicated in mucus production, but the mechanistic relationships between these molecules are not yet well understood. To address this, we established a primary normal human bronchial epithelial cell culture system with IL-13–induced mucus production and gene transcript expression changes similar to those seen in vivo in mice. IL-13 did not stimulate release of the EGFR ligand, transforming growth factor (TGF)-α. However, there was constitutive release of TGF-α from normal human bronchial epithelial cells, and inhibition of TGF-α or EGFR reduced both constitutive and IL-13–induced mucin production. Microarray analysis revealed that IL-13 and the EGFR pathway appear to have almost completely independent effects on transcript expression. IL-13 induced a relatively small set of transcripts, including several novel transcripts that might play a r...