Dysregulated interleukin-8 secretion and NF-kappaB activity in human cystic fibrosis nasal epithelial cells.
BACKGROUND
It is not clear whether cystic fibrosis (CF) airway inflammation is a consequence of bacterial infection or is intrinsically dysregulated. The aim of this study was to investigate IL-8 secretion and NF-kappaB activity in primary respiratory epithelial cells cultured from nasal polyps obtained from CF and non-CF subjects.


METHODS
NF-kappaB activity was studied by electrophoretic mobility-shift and quantitative colorimetric assays in nuclear extracts. Immunoreactive IL-8 levels were assessed by ELISA in cell culture supernatants. Both parameters were studied at baseline and following challenge with Pseudomonas aeruginosa or stimulation with pro-inflammatory cytokines.


RESULTS
Under basal conditions, CF cells presented a significant higher activity of NF-kappaB than non-CF cells (P=0.0004). P. aeruginosa challenge and IL-1beta/H2O2 co-stimulation caused four and two fold induction of NF-kappaB activity in non-CF and CF cells, respectively. IL-8 levels in unstimulated CF cells were significantly higher than in non-CF cells (P=0.0025). Upon incubation with P. aeruginosa and IL-1beta/H2O2, non-CF cells produced 6.3 times more IL-8 than unstimulated cells, whereas IL-8 secretion increased only of 1.4 times in CF cells.


CONCLUSIONS
CF respiratory epithelial cells exhibit a basal dysregulated production of IL-8 that partially correlates to enhanced NF-kappaB activity. Our data corroborate the hypothesis of a basal exaggerated inflammatory response in the CF respiratory epithelium.
Institute for Experimental Treatment of Cystic Fibrosis, H.S. Raffaele, Via Olgettina 58, 20132 Milano, Italy.
Salvatore
S
Carrabino
Daniela
D
Carpani
Alessandra
A
Livraghi
Maurizio
M
Di Cicco
Diana
D
Costantini
Elena
E
Copreni
Carla
C
Colombo
Massimo
M
Conese
D002478:Cells, Cultured; D003550:Cystic Fibrosis / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D016209:Interleukin-8 / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D009297:Nasal Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000502:physiology
C508606:CXCL8 protein, human; D007375:Interleukin-1; D016209:Interleukin-8; D016328:NF-kappa B; D006861:Hydrogen Peroxide