title: Cigarette smoke augments MUC5AC production via the TLR3-EGFR pathway in airway epithelial cells.
abstract: BACKGROUND
  Viral infections are a major cause of chronic obstructive pulmonary disease (COPD) exacerbations. Toll-like receptor 3 (TLR3) reacts with double-stranded RNA (dsRNA) and participates in the immune response after viral infection. In the present study, we examined whether cigarette smoke, which is involved in the pathogenesis of COPD, enhances mucin production via the TLR3-epidermal growth factor receptor (EGFR) pathway in airway epithelial cells.
  
  
  METHODS
  We studied the effects of cigarette smoke extract (CSE) on signal transduction and the production of mucin 5AC (MUC5AC) in NCI-H292 cells and differentiated primary human bronchial epithelial cells stimulated with a synthetic dsRNA analogue, polyinosinic-polycytidylic acid [poly(I:C)], used as a TLR3 ligand.
  
  
  RESULTS
  CSE significantly potentiated the production of MUC5AC in epithelial cells stimulated with poly(I:C). Antibodies to EGFR or EGFR ligands inhibited CSE-augmented MUC5AC release in poly(I:C)-treated cells. Treatment with poly(I:C) or CSE alone increased the phosphorylation of EGFR and extracellular signal-regulated kinase (ERK). However, after poly(I:C) stimulation, CSE did not enhance EGFR phosphorylation, but did augment ERK phosphorylation. EGFR inhibitors and an ERK inhibitor inhibited the augmented release of MUC5AC. In addition, treatment with N-acetylcysteine, an antioxidant, inhibited the CSE-augmented phosphorylation of ERK and MUC5AC.
  
  
  CONCLUSIONS
  These data show that cigarette smoke increases TLR3-stimulated MUC5AC production in airway epithelial cells, mainly via ERK signaling. The effect might be mediated in part by oxidative stress. Modulation of this pathway might be a therapeutic target for viral-induced mucin overproduction in COPD exacerbation.
authors.affiliation: Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan. Electronic address: kanaik@wakayama-med.ac.jp.
authors.forename: Kuninobu
authors.initials: K
authors.lastname: Kanai
authors.affiliation: Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan. Electronic address: koarai@rm.med.tohoku.ac.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Koarai
authors.affiliation: Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan. Electronic address: Yutaka.Sisikura@mc2.seikyou.ne.jp.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Shishikura
authors.affiliation: Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan. Electronic address: sugiura@rm.med.tohoku.ac.jp.
authors.forename: Hisatoshi
authors.initials: H
authors.lastname: Sugiura
authors.affiliation: Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan. Electronic address: 1kawa@wakayama-med.ac.jp.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Ichikawa
authors.affiliation: Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan. Electronic address: kikuchi@wakayama-med.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kikuchi
authors.affiliation: Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan. Electronic address: akamatsu@wakayama-med.ac.jp.
authors.forename: Keiichiro
authors.initials: K
authors.lastname: Akamatsu
authors.affiliation: Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan. Electronic address: tsuna@wakayama-med.ac.jp.
authors.forename: Tsunahiko
authors.initials: T
authors.lastname: Hirano
authors.affiliation: Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan. Electronic address: masa-n@wakayama-med.ac.jp.
authors.forename: Masanori
authors.initials: M
authors.lastname: Nakanishi
authors.affiliation: Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan. Electronic address: kazmatsu@wakayama-med.ac.jp.
authors.forename: Kazuto
authors.initials: K
authors.lastname: Matsunaga
authors.affiliation: Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan. Electronic address: minakaty@wakayama-med.ac.jp.
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Minakata
authors.affiliation: Department of Respiratory Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan. Electronic address: ichinose@rm.med.tohoku.ac.jp.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Ichinose
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000906:Antibodies / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D001980:Bronchi / Q000166:cytology*; D045744:Cell Line, Tumor; D004847:Epithelial Cells / Q000378:metabolism*; D066246:ErbB Receptors / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D008024:Ligands; D058990:Molecular Targeted Therapy; D055271:Mucin 5AC / Q000096:biosynthesis* / Q000378:metabolism; D018384:Oxidative Stress / Q000502:physiology; D010766:Phosphorylation; D011070:Poly I-C / Q000494:pharmacology; D029424:Pulmonary Disease, Chronic Obstructive / Q000209:etiology / Q000628:therapy; D015398:Signal Transduction / Q000502:physiology*; D012906:Smoke / Q000009:adverse effects; D014026:Nicotiana; D051196:Toll-Like Receptor 3 / Q000502:physiology*; D014777:Virus Diseases / Q000150:complications
chemical_list: D000906:Antibodies; D000975:Antioxidants; D008024:Ligands; C524678:MUC5AC protein, human; D055271:Mucin 5AC; D012906:Smoke; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; C512478:EGFR protein, human; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D011070:Poly I-C; D000111:Acetylcysteine
keywords: COPD; Exacerbation; Mucin; Oxidative stress; Toll-like receptor 3