Susceptibility of primary human airway epithelial cells to Bordetella pertussis adenylate cyclase toxin in two- and three-dimensional culture conditions

Abstract

The human pathogen Bordetella pertussis targets the respiratory epithelium and causes whooping cough. Its virulence factor adenylate cyclase toxin (CyaA) plays an important role in the course of infection. Previous studies on the impact of CyaA on human epithelial cells have been carried out using cell lines derived from the airways or the intestinal tract. Here, we investigated the interaction of CyaA and its enzymatically inactive but fully pore-forming toxoid CyaA-AC– with primary human airway epithelial cells (hAEC) derived from different anatomical sites (nose and tracheo-bronchial region) in two-dimensional culture conditions. To assess possible differences between the response of primary hAEC and respiratory cell lines directly, we included HBEC3-KT in our studies. In comparative analyses, we studied the impact of both the toxin and the toxoid on cell viability, intracellular cAMP concentration and IL-6 secretion. We found that the selected hAEC, which lack CD11b, were differentially susceptible to both CyaA and CyaA-AC–. HBEC3-KT appeared not to be suitable for subsequent analyses. Since the nasal epithelium first gets in contact with airborne pathogens, we further studied the effect of CyaA and its toxoid on the innate immunity of three-dimensional tissue models of the human nasal mucosa. The present study reveals first insights in toxin–cell interaction using primary hAEC.