title: Cigarette smoke causes caspase-independent apoptosis of bronchial epithelial cells from asthmatic donors.
abstract: BACKGROUND
  Epidemiologic studies have demonstrated important links between air pollution and asthma. Amongst these pollutants, environmental cigarette smoke is a risk factor both for asthma pathogenesis and exacerbation. As the barrier to the inhaled environment, the bronchial epithelium is a key structure that is exposed to cigarette smoke.
  
  
  OBJECTIVE
  Since primary bronchial epithelial cells (PBECs) from asthmatic donors are more susceptible to oxidant-induced apoptosis, we hypothesized that they would be susceptible to cigarette smoke-induced cell death.
  
  
  METHODS
  PBECs from normal and asthmatic donors were exposed to cigarette smoke extract (CSE); cell survival and apoptosis were assessed by fluorescence-activated cell sorting, and protective effects of antioxidants evaluated. The mechanism of cell death was evaluated using caspase inhibitors and immunofluorescent staining for apoptosis-inducing factor (AIF).
  
  
  RESULTS
  Exposure of PBEC cultures to CSE resulted in a dose-dependent increase in cell death. At 20% CSE, PBECs from asthmatic donors exhibited significantly more apoptosis than cells from non-asthmatic controls. Reduced glutathione (GSH), but not ascorbic acid (AA), protected against CSE-induced apoptosis. To investigate mechanisms of CSE-induced apoptosis, caspase-3 or -9 inhibitors were tested, but these failed to prevent apoptosis; in contrast, CSE promoted nuclear translocation of AIF from the mitochondria. GSH reduced the number of nuclear-AIF positive cells whereas AA was ineffective.
  
  
  CONCLUSIONS
  Our results show that PBECs from asthmatic donors are more susceptible to CSE-induced apoptosis. This response involves AIF, which has been implicated in DNA damage and ROS-mediated cell-death. Epithelial susceptibility to CSE may contribute to the impact of environmental tobacco smoke in asthma.
authors: Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton Faculty of Medicine, University Hospital Southampton, Southampton, United Kingdom; Dipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche (BIONEC), University of Palermo, Palermo, Italy; Istituto Euro-Mediterraneo di Scienza e Tecnologia (IEMEST), Palermo, Italy; Institute of Biomedicine and Molecular Immunology (IBIM), Italian National Research Council (CNR), Palermo, Italy.
authors: Fabio
authors: F
authors: Bucchieri
authors: Dipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche (BIONEC), University of Palermo, Palermo, Italy; Istituto Euro-Mediterraneo di Scienza e Tecnologia (IEMEST), Palermo, Italy.
authors: Antonella
authors: A
authors: Marino Gammazza
authors: Dipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche (BIONEC), University of Palermo, Palermo, Italy; Istituto Euro-Mediterraneo di Scienza e Tecnologia (IEMEST), Palermo, Italy.
authors: Alessandro
authors: A
authors: Pitruzzella
authors: Dipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche (BIONEC), University of Palermo, Palermo, Italy; Istituto Euro-Mediterraneo di Scienza e Tecnologia (IEMEST), Palermo, Italy.
authors: Alberto
authors: A
authors: Fucarino
authors: Dipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche (BIONEC), University of Palermo, Palermo, Italy.
authors: Felicia
authors: F
authors: Farina
authors: Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton Faculty of Medicine, University Hospital Southampton, Southampton, United Kingdom; Southampton National Institute for Health Research (NIHR) Respiratory Biomedical Research Unit, Sir Henry Wellcome Laboratories, University of Southampton Faculty of Medicine, University Hospital Southampton, Southampton, United Kingdom.
authors: Peter
authors: P
authors: Howarth
authors: Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton Faculty of Medicine, University Hospital Southampton, Southampton, United Kingdom; Southampton National Institute for Health Research (NIHR) Respiratory Biomedical Research Unit, Sir Henry Wellcome Laboratories, University of Southampton Faculty of Medicine, University Hospital Southampton, Southampton, United Kingdom.
authors: Stephen T
authors: ST
authors: Holgate
authors: Dipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche (BIONEC), University of Palermo, Palermo, Italy.
authors: Giovanni
authors: G
authors: Zummo
authors: Academic Unit of Clinical and Experimental Sciences, Sir Henry Wellcome Laboratories, University of Southampton Faculty of Medicine, University Hospital Southampton, Southampton, United Kingdom; Southampton National Institute for Health Research (NIHR) Respiratory Biomedical Research Unit, Sir Henry Wellcome Laboratories, University of Southampton Faculty of Medicine, University Hospital Southampton, Southampton, United Kingdom.
authors: Donna E
authors: DE
authors: Davies
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D001980:Bronchi / Q000166:cytology*; D053148:Caspase 3; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012907:Smoking / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D000975:Antioxidants; D053148:Caspase 3