title: Carbon nanoparticles induce ceramide- and lipid raft-dependent signalling in lung epithelial cells: a target for a preventive strategy against environmentally-induced lung inflammation.
abstract: BACKGROUND
  Particulate air pollution in lung epithelial cells induces pathogenic endpoints like proliferation, apoptosis, and pro-inflammatory reactions. The activation of the epidermal growth factor receptor (EGFR) is a key event responsible for signalling events involving mitogen activated protein kinases specific for these endpoints. The molecular events leading to receptor activation however are not well understood. These events are relevant for the toxicological evaluation of inhalable particles as well as for potential preventive strategies in situations when particulate air pollution cannot be avoided. The current study therefore had the objective to elucidate membrane-coupled events leading to EGFR activation and the subsequent signalling cascade in lung epithelial cells. Furthermore, we aimed to identify the molecular target of ectoine, a biophysical active substance which we described to prevent carbon nanoparticle-induced lung inflammation.
  
  
  METHODS
  Membrane signalling events were investigated in isolated lipid rafts from lung epithelial cells with regard to lipid and protein content of the signalling platforms. Using positive and negative intervention approaches, lipid raft changes, subsequent signalling events, and lung inflammation were investigated in vitro in lung epithelial cells (RLE-6TN) and in vivo in exposed animals.
  
  
  RESULTS
  Carbon nanoparticle treatment specifically led to an accumulation of ceramides in lipid rafts. Detailed analyses demonstrated a causal link of ceramides and subsequent EGFR activation coupled with a loss of the receptor in the lipid raft fractions. In vitro and in vivo investigations demonstrate the relevance of these events for carbon nanoparticle-induced lung inflammation. Moreover, the compatible solute ectoine was able to prevent ceramide-mediated EGFR phosphorylation and subsequent signalling as well as lung inflammation in vivo.
  
  
  CONCLUSIONS
  The data identify a so far unknown event in pro-inflammatory signalling and contribute to the understanding of particle cell interaction and therefore to risk identification and risk assessment of inhalable xenobiotics. Moreover, as this cellular reaction can be prevented by the well tolerated substance ectoine, a molecular preventive strategy for susceptible persons against airway inflammation is proposed.
authors.affiliation: IUF Leibniz-Institut für Umweltmedizinische Forschung, Auf'm Hennekamp 50, 40225 Düsseldorf, Germany.
authors.forename: Henrike
authors.initials: H
authors.lastname: Peuschel
authors.forename: Ulrich
authors.initials: U
authors.lastname: Sydlik
authors.forename: Susanne
authors.initials: S
authors.lastname: Grether-Beck
authors.forename: Ingo
authors.initials: I
authors.lastname: Felsner
authors.forename: Daniel
authors.initials: D
authors.lastname: Stöckmann
authors.forename: Sascha
authors.initials: S
authors.lastname: Jakob
authors.forename: Matthias
authors.initials: M
authors.lastname: Kroker
authors.forename: Judith
authors.initials: J
authors.lastname: Haendeler
authors.forename: Marijan
authors.initials: M
authors.lastname: Gotić
authors.forename: Christiane
authors.initials: C
authors.lastname: Bieschke
authors.forename: Jean
authors.initials: J
authors.lastname: Krutmann
authors.forename: Klaus
authors.initials: K
authors.lastname: Unfried
mesh_terms: D000599:Amino Acids, Diamino / Q000494:pharmacology*; D000818:Animals; D002244:Carbon / Q000633:toxicity*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002518:Ceramides / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D008168:Lung / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D021962:Membrane Microdomains / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D053758:Nanoparticles / Q000633:toxicity*; D052638:Particulate Matter / Q000633:toxicity*; D011014:Pneumonia / Q000473:pathology / Q000517:prevention & control*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000599:Amino Acids, Diamino; D002518:Ceramides; D052638:Particulate Matter; D017382:Reactive Oxygen Species; D002244:Carbon; C045628:ectoine; D066246:ErbB Receptors; C504327:N-(alpha-hydroxyoctadecanoyl)phytosphingosine