title: Bronchiolar chemokine expression is different after single versus repeated cigarette smoke exposure.
abstract: BACKGROUND
  Bronchioles are critical zones in cigarette smoke (CS)-induced lung inflammation. However, there have been few studies on the in vivo dynamics of cytokine gene expression in bronchiolar epithelial cells in response to CS.
  
  
  METHODS
  We subjected C57BL/6J mice to CS (whole body exposure, 90 min/day) for various periods, and used laser capture microdissection to isolate bronchiolar epithelial cells for analysis of mRNA by quantitative reverse transcription-polymerase chain reaction.
  
  
  RESULTS
  We detected enhanced expression of keratinocyte-derived chemokine (KC), macrophage inflammatory protein-2 (MIP-2), tumor necrosis factor-alpha (TNF-alpha), and interleukin-1beta (IL-1beta) by bronchial epithelial cells after 10 consecutive days of CS exposure. This was mirrored by increases in neutrophils and KC, MIP-2, TNF-alpha, and IL-1beta proteins in the bronchoalveolar lavage (BAL) fluid. The initial inhalation of CS resulted in rapid and robust upregulation of KC and MIP-2 with concomitant DNA oxidation within 1 hr, followed by a return to control values within 3 hrs. In contrast, after CS exposure for 10 days, this initial surge was not observed. As the CS exposure was extended to 4, 12, 18 and 24 weeks, the bronchiolar KC and MIP-2 expression and their levels in BAL fluid were relatively dampened compared to those at 10 days. However, neutrophils in BAL fluid continuously increased up to 24 weeks, suggesting that neutrophil accumulation as a result of long-term CS exposure became independent of KC and MIP-2.
  
  
  CONCLUSIONS
  These findings indicate variable patterns of bronchiolar epithelial cytokine expression depending on the duration of CS exposure, and that complex mechanisms govern bronchiolar molecular dynamics in vivo.
authors.affiliation: First Department of Medicine, Hokkaido University School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo, 060-8683, Japan. bytomoko@med.hokudai.ac.jp
authors.forename: Tomoko
authors.initials: T
authors.lastname: Betsuyaku
authors.forename: Ichiro
authors.initials: I
authors.lastname: Hamamura
authors.forename: Junko
authors.initials: J
authors.lastname: Hata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takahashi
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Mitsuhashi
authors.forename: Tracy L
authors.initials: TL
authors.lastname: Adair-Kirk
authors.forename: Robert M
authors.initials: RM
authors.lastname: Senior
authors.forename: Masaharu
authors.initials: M
authors.lastname: Nishimura
mesh_terms: D000818:Animals; D001980:Bronchi / Q000187:drug effects / Q000378:metabolism*; D018925:Chemokines / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D019570:Inhalation Exposure; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012906:Smoke; D013638:Tars / Q000494:pharmacology*; D014028:Tobacco Smoke Pollution
chemical_list: D018925:Chemokines; D012906:Smoke; D013638:Tars; D014028:Tobacco Smoke Pollution; C024746:tobacco tar