title: Inflammatory and cytotoxic effects of acrolein, nicotine, acetylaldehyde and cigarette smoke extract on human nasal epithelial cells.
abstract: BACKGROUND
  Cigarette smoke induces a pro-inflammatory response in airway epithelial cells but it is not clear which of the various chemicals contained within cigarette smoke (CS) should be regarded as predominantly responsible for these effects. We hypothesised that acrolein, nicotine and acetylaldehyde, important chemicals contained within volatile cigarette smoke in terms of inducing inflammation and causing addiction, have immunomodulatory effects in primary nasal epithelial cell cultures (PNECs).
  
  
  METHODS
  PNECs from 19 healthy subjects were grown in submerged cultures and were incubated with acrolein, nicotine or acetylaldehyde prior to stimulation with Pseudomonas aeruginosa lipopolysaccharide (PA LPS). Experiments were repeated using cigarette smoke extract (CSE) for comparison. IL-8 was measured by ELISA, activation of NF-κB by ELISA and Western blotting, and caspase-3 activity by Western blotting. Apoptosis was evaluated using Annexin-V staining and the terminal transferase-mediated dUTP nick end-labeling (TUNEL) method.
  
  
  RESULTS
  CSE was pro-inflammatory after a 24 h exposure and 42% of cells were apoptotic or necrotic after this exposure time. Acrolein was pro-inflammatory for the PNEC cultures (30 μM exposure for 4 h inducing a 2.0 fold increase in IL-8 release) and also increased IL-8 release after stimulation with PA LPS. In contrast, nicotine had anti-inflammatory properties (0.6 fold IL-8 release after 50 μM exposure to nicotine for 24 h), and acetylaldehyde was without effect. Acrolein and nicotine had cellular stimulatory and anti-inflammatory effects respectively, as determined by NF-κB activation. Both chemicals increased levels of cleaved caspase 3 and induced cell death.
  
  
  CONCLUSIONS
  Acrolein is pro-inflammatory and nicotine anti-inflammatory in PNEC cultures. CSE induces cell death predominantly by apoptotic mechanisms.
authors.forename: David M
authors.initials: DM
authors.lastname: Comer
authors.forename: Joseph Stuart
authors.initials: JS
authors.lastname: Elborn
authors.affiliation: Centre for Infection and Immunity, Health Sciences Building, School of Medicine, Dentistry and Biomedical Sciences, Queen's University of Belfast, 97 Lisburn Road, Belfast BT9 7BL, UK. m.ennis@qub.ac.uk.
authors.forename: Madeleine
authors.initials: M
authors.lastname: Ennis
mesh_terms: D000079:Acetaldehyde / Q000009:adverse effects*; D000171:Acrolein / Q000009:adverse effects*; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced*; D009297:Nasal Mucosa / Q000166:cytology* / Q000187:drug effects*; D009538:Nicotine / Q000009:adverse effects*; D012906:Smoke / Q000009:adverse effects*; D014026:Nicotiana / Q000009:adverse effects*
chemical_list: D012906:Smoke; D009538:Nicotine; D000171:Acrolein; D000079:Acetaldehyde