To Örebro University

Respiratory Epithelium. Örebro Studies in Medicine 99. Cystic fibrosis (CF) is caused by a mutation in a cAMP-activated chloride (Cl-) channel (CFTR). Mortality and morbidity in CF is mainly due to the deregulated responses of the airway epithelial cells. The purpose of the thesis was to investigate the behaviour of the airway epithelial cells that are involved in maintaining the homeostasis in the airways.

Nasal brush biopsies obtained from anesthetized human nasal mucosa can be an easy source to establish primary epithelial cell lines (Paper I). We found that CF and non CF cellular models cannot fully show the relation between CFTR and the phenotypic differences between CF and healthy cells (Paper II). The possibility to correct the Cl- transport defect in CF by the use of stable NOdonors, and ambroxol was investigated. NO-donors stimulated Cl- efflux, and decreased ENaC mRNA expression in CFBE cells (Paper III), while ambroxol increased Cl- efflux from CFBE cells, and showed a positive effect on the biosynthesis of CFTR (Paper IV). This suggests that these substances may be a potentially interesting group of compounds for the treatment of CF. Increased levels of IL-6 and IL-8 upon infection in CF cells can increase the susceptibility of P. aeruginosa infected CF cells to apoptosis and/or internalization of these bacteria in CF cells and hence, may have important roles in the pathology of P. aeruginosa infection in CF airways. If internalization is beneficial for the host then glucocorticoids (GCs) are not beneficial for the treatment of CF patients. However, GCs may improve airway hydration. Whether the benefits of GC treatment outweigh the negative effects is questionable, and further clinical studies need to be carried out (Paper V). The neonatal isolates S. epidermidis 94B080 and S. aureus 90B083 can modulate CFTR and ENaC expression in airway epithelial cells, which may disturb the ion transport in the respiratory epithelium upon bacterial exposure. Airway epithelial cells also show excessive inflammatory responses to these bacteria, which means that these bacteria may induce pulmonary inflammation (Paper VI).