Cigarette smoke alters respiratory syncytial virus-induced apoptosis and replication

Dayna J. Groskreutz, Martha M. Monick, Ellen C. Babor, Toru Nyunoya, Steven M. Varga, Dwight C. Look, Gary W. Hunninghake

Research output: Contribution to journalArticlepeer-review

31 Scopus citations

Abstract

Individuals exposed to cigarette smoke have a greater number and severity of viral infections, including respiratory syncytial virus (RSV) infections, than do nonsmokers, but the cellular mechanism is unknown. Our objective was to determine the mechanism by which cigarette smoke augments viral infection. We hypothesize that cigarette smoke causes necrosis and prevents virus-induced cellular apoptosis, and that this is associated with increased inflammation and viral replication. Primary airway epithelial cells were exposed to cigarette smoke extract for 2 days, followed by 1 day of RSV exposure. Western blot detection of cleaved caspases 3 and 7 showed less apoptosis when cells were treated with cigarette smoke before viral infection. This finding was confirmed with ELISA and TUNEL detection of apoptosis. Measures of cell viability, including propidium iodide staining, ATP assay, and cell counts, indicated that cigarettesmokecauses necrosis rather than virus-induced apoptosis. Using plaque assay and fluorescently-labeled RSV, we showed that although there were less live cells in the cigarette smoke-pretreated group, viral load was increased. The effect was inhibited by pretreatment of cells with N-acetylcysteine and aldehyde dehydrogenase, suggesting that the effect was primarily mediated by reactive aldehydes. Cigarette smoke causes necrosis rather than apoptosis in viral infection, resulting in increased inflammation and enhanced viral replication.

Original languageEnglish
Pages (from-to)189-198
Number of pages10
JournalAmerican Journal of Respiratory Cell and Molecular Biology
Volume41
Issue number2
DOIs
StatePublished - Aug 1 2009

Keywords

  • Apoptosis
  • Cigarette smoke
  • Necrosis
  • Respiratory syncytial virus

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