title: The up-regulation of heme oxygenase-1 expression in human gingival fibroblasts stimulated with nicotine.
abstract: BACKGROUND
  Cigarette smoking is a major risk factor in the development and further progression of periodontal diseases. Heme oxygenase-1 (HO-1) is known as a stress-inducible protein and functions as an antioxidant enzyme. There is limited information on the expression of HO-1 in smoking-associated periodontal disease.
  
  
  OBJECTIVE
  The aim of the present study was to investigate the effects of nicotine on the expression of HO-1 protein in cultured human gingival fibroblasts in vitro and further to compare HO-1 expression in gingival tissues obtained from cigarette smokers and non-smokers in vivo.
  
  
  METHODS
  Western blot assay was used to investigate the effects on human gingival fibroblasts exposed to nicotine. In addition, antioxidants catalase, superoxide dismutase (SOD), and N-acetyl-l-cysteine (NAC) were added to test how they modulated the effects on nicotine-induced HO-1 expression. Gingival biopsies taken from the flap surgery of 20 male patients with periodontal disease (10 cigarette smokers and 10 non-smokers) were examined by immunohistochemistry.
  
  
  RESULTS
  The exposure of quiescent human gingival fibroblasts to 10 mm nicotine resulted in the induction of HO-1 protein expression in a time-dependent manner (p < 0.05). The addition of glutathione (GSH) precursor NAC inhibited the nicotine-induced HO-1 protein expression (p < 0.05). However, SOD and catalase did not decrease the nicotine-induced HO-1 protein expression (p > 0.05). The results from immunohistochemistry demonstrated that HO-1 expression was significantly higher in cigarette smokers (p < 0.05). HO-1 was noted in the basal layers of epithelium, inflammatory cells, and fibroblasts in specimens from cigarette smoking.
  
  
  CONCLUSIONS
  Taken together, these results suggest that HO-1 expression is significantly up-regulated in gingival tissues from cigarette smokers, and nicotine may, among other constituents, be responsible for the enhanced HO-1 expression in vivo. The regulation of HO-1 expression induced by nicotine is critically dependent on the intracellular GSH concentration.
authors.affiliation: Institute of Stomatology, College of Oral Medicine, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Yu-Chao
authors.initials: YC
authors.lastname: Chang
authors.forename: Chung-Chih
authors.initials: CC
authors.lastname: Lai
authors.forename: Li-Fen
authors.initials: LF
authors.lastname: Lin
authors.forename: Wei-Fen
authors.initials: WF
authors.lastname: Ni
authors.forename: Chung-Hung
authors.initials: CH
authors.lastname: Tsai
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002374:Catalase / Q000494:pharmacology; D002417:Cattle; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D005731:Ganglionic Stimulants / Q000009:adverse effects*; D005881:Gingiva / Q000187:drug effects* / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051547:Heme Oxygenase-1; D006801:Humans; D008297:Male; D008565:Membrane Proteins; D009538:Nicotine / Q000009:adverse effects*; D012907:Smoking / Q000009:adverse effects; D013482:Superoxide Dismutase / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: D000975:Antioxidants; D005731:Ganglionic Stimulants; D008565:Membrane Proteins; D009538:Nicotine; D002374:Catalase; C496541:HMOX1 protein, human; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D013482:Superoxide Dismutase; D000111:Acetylcysteine