title: Neutrophils augment LPS-mediated pro-inflammatory signaling in human lung epithelial cells.
abstract: BACKGROUND
  The role of polymorphonuclear neutrophils in pulmonary host defense is well recognized. The influence of a pre-existing inflammation driven by neutrophils (neutrophilic inflammation) on the airway epithelial response toward pro-inflammatory exogenous triggers, however, is still poorly addressed. Therefore, the aim of the present study is to investigate the effect of neutrophils on lipopolysaccharide (LPS)-induced pro-inflammatory signaling in lung epithelial cells. Additionally, underlying signaling pathways are examined.
  
  
  METHODS
  Human bronchial epithelial cells (BEAS-2B) were co-incubated with human peripheral blood neutrophils or bone-marrow derived neutrophils from either C57BL/6J wild type or nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase deficient (p47(phox-/-)) mice. Upon stimulation with LPS, interleukin (IL)-8 production and reactive oxygen species (ROS) generation were measured. Additionally, activation of the extracellular signal-regulated kinases (ERK) 1/2 and nuclear factor (NF)-κB signaling pathways was analyzed.
  
  
  RESULTS
  Our studies show that the presence of neutrophils synergistically increases LPS-induced IL-8 and ROS production by BEAS-2B cells without inducing cytotoxicity. The observed IL-8 response to endotoxin increases in proportion to time, LPS-concentration and the number of neutrophils present. Moreover, this synergistic IL-8 production strongly correlated with the chemotactic properties of the co-incubations and significantly depended on a functional neutrophilic NADPH oxidase. The presence of neutrophils also augments LPS-induced phosphorylation of ERK1/2 and IκBα as well as NF-κB RelA DNA binding activity in BEAS-2B cells.
  
  
  CONCLUSIONS
  Our results indicate that the pro-inflammatory effects of LPS toward lung epithelial cells are amplified during a pre-existing neutrophilic inflammation. These findings support the concept that patients suffering from pulmonary neutrophilic inflammation are more susceptible toward exogenous pro-inflammatory triggers.
authors.affiliation: IUF-Leibniz Institut für Umweltmedizinische Forschung at the Heinrich Heine University, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.
authors.forename: Agnes W
authors.initials: AW
authors.lastname: Boots
authors.forename: Kirsten
authors.initials: K
authors.lastname: Gerloff
authors.forename: Roger
authors.initials: R
authors.lastname: Bartholomé
authors.forename: Damien
authors.initials: D
authors.lastname: van Berlo
authors.forename: Kirstin
authors.initials: K
authors.lastname: Ledermann
authors.forename: Guido R M M
authors.initials: GR
authors.lastname: Haenen
authors.forename: Aalt
authors.initials: A
authors.lastname: Bast
authors.forename: Frederik-Jan
authors.initials: FJ
authors.lastname: van Schooten
authors.forename: Catrin
authors.initials: C
authors.lastname: Albrecht
authors.forename: Roel P F
authors.initials: RP
authors.lastname: Schins
mesh_terms: D000818:Animals; D002460:Cell Line; D002469:Cell Separation; D002630:Chemotactic Factors / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D007249:Inflammation / Q000473:pathology*; D016209:Interleukin-8 / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008168:Lung / Q000473:pathology*; D051379:Mice; D008954:Models, Biological; D019255:NADPH Oxidases / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology / Q000473:pathology*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D051996:Transcription Factor RelA / Q000378:metabolism
chemical_list: D002630:Chemotactic Factors; D020672:I-kappa B Proteins; D016209:Interleukin-8; D008070:Lipopolysaccharides; C000606204:NFKBIA protein, human; C000606205:Nfkbia protein, mouse; D017382:Reactive Oxygen Species; D051996:Transcription Factor RelA; D000072000:NF-KappaB Inhibitor alpha; D004247:DNA; D019255:NADPH Oxidases; D048049:Extracellular Signal-Regulated MAP Kinases