Hepatocyte growth factor and other fibroblast secretions modulate the phenotype of human bronchial epithelial cells

Abstract
The luminal airway surface is lined with epithelial cells that provide a protective barrier from the external environment and clear inhaled pathogens from the lung. To accomplish this important function, human bronchial epithelial (HBE) cells must be able to rapidly regenerate a mucociliary layer of cells following epithelial injury. Whereas epithelial-fibroblast interactions are known to modulate the airway architecture during lung development and repair, little is known about how these two cells interact. Using a primary HBE and lung fibroblast coculture system, we demonstrate that 1 ) subepithelial fibroblasts provide a suitable environment for differentiation of HBE cells into a polarized ciliated phenotype despite being cultured in media that induces terminal squamous differentiation and growth arrest in the absence of fibroblasts, 2 ) HBE cells cocultured with subepithelial fibroblasts exhibit augmented ciliogenesis, accelerated wound repair, and diminished polarized ion transport compared with cells grown in control conditions, and 3 ) hepatocyte growth factor (HGF) is important for subepithelial fibroblast modulation of HBE cell differentiation. These results provide a model to study fibroblast modulation of epithelial phenotype and indicate that HGF secreted by subepithelial fibroblasts contributes to HBE cell differentiation.