NF-kappaB activation and sustained IL-8 gene expression in primary cultures of cystic fibrosis airway epithelial cells stimulated with Pseudomonas aeruginosa.
The progression of lung disease in cystic fibrosis (CF) is characterized by an exuberant inflammatory response mounted by the respiratory epithelium that is further exacerbated by bacterial infection. Recent studies have demonstrated upregulation of nuclear factor-kappaB (NF-kappaB) in response to infection in genetically modified cell culture models, which is associated with expression of interleukin (IL)-8. Using human airway epithelial cells grown in primary culture, we examined in vitro activation of NF-kappaB in cells isolated from five CF (DeltaF508/DeltaF508) and three non-CF (NCF) patients in response to Pseudomonas aeruginosa. Immunofluorescence, gel-shift, and immunoblot assays demonstrated a rapid translocation of NF-kappaB subunits (p50 and p65) to the nucleus in both CF and NCF cell cultures. However, nuclear extracts from CF cells both before and following P. aeruginosa stimulation revealed elevated NF-kappaB activation compared with NCF cells. Additionally, elevated nuclear levels of the NF-kappaB inhibitor IkappaBalpha were detected in nuclei of CF cells after P. aeruginosa stimulation, but this increase was transient. There was no difference in IL-8 mRNA levels between CF and NCF cells early after stimulation, whereas expression was higher and sustained in CF cells at later times. Our results also demonstrated increased baseline translocation of NF-kappaB to nuclei of primary CF epithelial cell cultures, but intranuclear IkappaBalpha may initially block its effects following P. aeruginosa stimulation. Thus, IL-8 mRNA expression was prolonged after P. aeruginosa stimulation in CF epithelial cells, and this sustained IL-8 expression may contribute to the excessive inflammatory response in CF.
Joseph
Theresa
T
Department of Pediatrics, Washington University School of Medcine, St. Louis, Missouri 63110, USA.
Look
Dwight
D
Ferkol
Thomas
T
D001692:Biological Transport; D002457:Cell Extracts / Q000737:chemistry; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D003550:Cystic Fibrosis / Q000378:metabolism* / Q000473:pathology; D004847:Epithelial Cells / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology; D015870:Gene Expression; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D008168:Lung / Q000737:chemistry / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D016328:NF-kappa B / Q000378:metabolism*; D020033:Protein Isoforms / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051996:Transcription Factor RelA
D002457:Cell Extracts; D020672:I-kappa B Proteins; D016209:Interleukin-8; D016328:NF-kappa B; D020033:Protein Isoforms; D012333:RNA, Messenger; D051996:Transcription Factor RelA