Interleukin-8 production by cystic fibrosis nasal epithelial cells after tumor necrosis factor-α and respiratory syncytial virus stimulation

High levels of neutrophils and the neutropil-attracting chemokine interleukin (IL)-8 have been observed in the airways of patients with cystic fibrosis (CF). We hypothesized that CF respiratory epithelium produces excessive amounts of IL-8 either at baseline or after stimulation. To test this hypothesis we compared immunoreactive IL-8 release by primary nasal epithelial cell (NEC) cultures established from young children with or without CF, at several time points after stimulation of cultures with tumor necrosis factor-alpha (TNF-alpha) or infection with respiratory syncytial virus (RSV). Both stimuli induced significantly increased IL-8 release by both CF and control cultures. However, there was no difference between CF and control cells in either the magnitude or duration of the IL-8 response. The effect of transduction of CF cells with Ad5-CBCFTR, an adenovirus vector mediating expression of cystic fibrosis transmembrane regulator (CFTR), on IL-8 production was also determined. TNF-alpha stimulated IL-8 production was not different in Ad5-CBCFTR-transduced, -untransduced, or Ad5-CMVLacZ-transduced control cells. Lastly, immortalized CF tracheal epithelial cell lines, both uncorrected and retrovirally corrected with CFTR, were compared. Again, TNF-alpha-stimulated IL-8 production did not differ significantly between cell lines with and without functioning CFTR. Our data suggest that isolated CF NECs cultured under these conditions do not produce more IL-8 than do non-CF control cultures, either at baseline or after incubation with the nonspecific stimuli TNF-alpha and RSV. We conclude that the absence of functioning CFTR alone is not sufficient to cause excessive production of IL-8.