Neutrophils augment LPS-mediated pro-inflammatory signaling in human lung epithelial cells

A.W. Boots, K. Gerloff, R. Bartholomé, D. van Berlo, K. Ledermann, G.R.M.M. Haenen, A. Bast, F.J. van Schooten, C. Albrecht, R.P. Schins

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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)-kappaB 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 IkappaBalpha as well as NF-kappaB 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.
Original languageEnglish
Pages (from-to)1151-1162
Number of pages12
JournalBiochimica et Biophysica Acta-Molecular Cell Research
Volume1823
Issue number7
DOIs
Publication statusPublished - Jul 2012

Keywords

  • BEAS-2B cell
  • Interleukin 8
  • NADPH oxidase
  • Reactive oxygen species
  • Synergism
  • NF-KAPPA-B
  • NADPH-OXIDASE
  • DEPENDENT REGULATION
  • ACTIVATOR PROTEIN-1
  • INTERLEUKIN-8 IL-8
  • GENE-EXPRESSION
  • HOST-DEFENSE
  • DNA-DAMAGE
  • RESPONSES
  • DISEASE

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