title: An environmental contaminant, benzo(a)pyrene, induces oxidative stress-mediated interleukin-8 production in human keratinocytes via the aryl hydrocarbon receptor signaling pathway.
abstract: BACKGROUND
  Benzo(a)pyrene (BaP) is an environmental contaminant found in cigarette smoke. It is well known that cigarette smoking exacerbates interleukin-8 (IL-8)-related inflammatory skin diseases such as psoriasis, palmoplantar pustulosis and acne. Although BaP has been shown to exert its biological effects via the aryl hydrocarbon receptor (AhR) signaling pathway, the mechanism of its inflammatory effects on skin remains unanswered.
  
  
  OBJECTIVE
  To elucidate whether or not BaP cause AhR activation and subsequent oxidative stress leading to IL-8 production in normal human epidermal keratinocytes (NHEKs).
  
  
  METHODS
  NHEKs exposed to BaP were analyzed. Immunofluorescence, real-time PCR, Western blotting, ELISA, reactive oxygen species (ROS) detection using H2DCFDA and RNA interference using si (small interfering) RNA were employed.
  
  
  RESULTS
  Immunofluorescence analysis clearly demonstrated that BaP induced nuclear translocation of AhR from cytoplasm. The AhR activation subsequently induced CYP1A1 mRNA and protein expression in a dose-dependent manner. In addition, ROS and IL-8 production were coordinately augmented by BaP, whereas this was not the case in IL-1α, IL-6, TNF-α or GM-CSF production. Knockdown of AhR expression using siRNA transfection inhibited BaP-induced-ROS and IL-8 production, suggesting that these responses are strongly dependent on the AhR signaling pathway. Furthermore, the addition of N-acetyl cystein or catalase cancelled the IL-8 production by BaP, indicating that ROS production is essential for IL-8 production.
  
  
  RESULTS
  This data highlights AhR-ROS-dependent regulation of IL-8 in NHEKs by BaP, providing a plausible explanation, at least in part, for why cigarette smoking exacerbates IL-8-related skin diseases such as psoriasis, palmoplantar pustulosis and acne.
authors.affiliation: Department of Dermatology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. gakku@dermatol.med.kyushu-u.ac.jp
authors.forename: Gaku
authors.initials: G
authors.lastname: Tsuji
authors.forename: Masakazu
authors.initials: M
authors.lastname: Takahara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Uchi
authors.forename: Satoshi
authors.initials: S
authors.lastname: Takeuchi
authors.forename: Chikage
authors.initials: C
authors.lastname: Mitoma
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Moroi
authors.forename: Masutaka
authors.initials: M
authors.lastname: Furue
mesh_terms: D001564:Benzo(a)pyrene / Q000737:chemistry*; D003593:Cytoplasm / Q000378:metabolism; D004777:Environment; D006801:Humans; D007249:Inflammation; D016209:Interleukin-8 / Q000378:metabolism*; D015603:Keratinocytes / Q000378:metabolism*; D018613:Microscopy, Confocal / Q000379:methods; D008856:Microscopy, Fluorescence / Q000379:methods; D008954:Models, Biological; D018384:Oxidative Stress; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000378:metabolism*; D015398:Signal Transduction; D012867:Skin / Q000378:metabolism
chemical_list: D016209:Interleukin-8; D017382:Reactive Oxygen Species; D018336:Receptors, Aryl Hydrocarbon; D001564:Benzo(a)pyrene