title: Cigarette smoke extract suppresses the RIG-I-initiated innate immune response to influenza virus in the human lung.
abstract: Cigarette smoking is the major cause of chronic obstructive pulmonary disease (COPD) and predisposes subjects to severe respiratory tract infections. Epidemiological studies have shown that cigarette smokers are seven times more likely to contract influenza infection than nonsmokers. The mechanisms underlying this increased susceptibility are poorly characterized. Retinoic acid-inducible gene (RIG)-I is believed to play an important role in the recognition of, and response to, influenza virus and other RNA viruses. Our study focused on how cigarette smoke extract (CSE) alters the influenza-induced proinflammatory response and suppresses host antiviral activity in the human lung using a unique lung organ culture model. We first determined that treatment with 2-20% CSE did not induce cytotoxicity as assessed by LDH release. However, CSE treatment inhibited influenza-induced IFN-inducible protein 10 protein and mRNA expression. Induction of the major antiviral cytokine IFN-β mRNA was also decreased by CSE. CSE also blunted viral-mediated RIG-I mRNA and protein expression. Inhibition of viral-mediated RIG-I induction by CSE was prevented by the antioxidants N-acetyl-cysteine and glutathione. These findings show that CSE suppresses antiviral and innate immune responses in influenza virus-infected human lungs through oxidative inhibition of viral-mediated induction of the pattern recognition receptor RIG-I. This immunosuppressive effect of CSE may play a role in the enhanced susceptibility of smokers to serious influenza infection in the lung.
authors.affiliation: Pulmonary and Critical Care Division, Department of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, USA.
authors.forename: Wenxin
authors.initials: W
authors.lastname: Wu
authors.forename: Krupa B
authors.initials: KB
authors.lastname: Patel
authors.forename: J Leland
authors.initials: JL
authors.lastname: Booth
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Jordan P
authors.initials: JP
authors.lastname: Metcalf
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D015153:Blotting, Western; D016207:Cytokines / Q000378:metabolism; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007113:Immunity, Innate / Q000187:drug effects*; D007124:Immunoenzyme Techniques; D007165:Immunosuppression Therapy; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000378:metabolism*; D016899:Interferon-beta / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008168:Lung / Q000821:virology*; D012333:RNA, Messenger / Q000235:genetics; D011971:Receptors, Immunologic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012907:Smoking / Q000009:adverse effects*
chemical_list: D000975:Antioxidants; D016207:Cytokines; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D016899:Interferon-beta; D007770:L-Lactate Dehydrogenase; C452820:RIGI protein, human; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases