title: Regulation of interleukin-6 expression by arecoline in human buccal mucosal fibroblasts is related to intracellular glutathione levels.
abstract: OBJECTIVE
  Cytokines play an important role in regulating fibroblast function and is likely to play a key role in regulating the initiation and progression of scarring in any fibrotic disease. Interleukin-6 (IL-6) has been implicated in the development of a variety of fibrotic diseases. The aim of this study was to compare IL-6 expression in fibroblasts cultured from normal human buccal mucosa and oral submucous fibrosis (OSF) specimens and further explore the potential mechanism that may lead to induce IL-6 expression.
  
  
  METHODS
  mRNA level of IL-6 in fibroblasts from OSF was compared with normal buccal mucosa. The effects of arecoline, the major areca nut alkaloid, on IL-6 expression in normal human buccal mucosa fibroblasts (BMFs) were measured in vitro. mRNA was quantified with AlphaImager 2000. To determine whether glutathione (GSH) levels were important in the induction of IL-6 by arecoline, we pretreated cells with 2-oxothiazolidine-4-carboxylic acid (OTZ) to boost GSH levels or with buthionine sulfoximine (BSO) to deplete GSH.
  
  
  RESULTS
  Fibroblasts derived from OSF exhibited higher IL-6 gene expression than BMF in mRNA levels (P < 0.05). The exposure of quiescent BMF to arecoline resulted in the elevation of IL-6 mRNA expression in a dose-dependent manner (P < 0.05). IL-6 gene regulated by arecoline correlated with intracellular GSH levels in BMF. Arecoline at a concentration of 129 muM induced about 2.7-fold IL-6 mRNA levels over the 6-h incubation period. However, BSO enhanced the IL-6 mRNA levels by 3.9-fold (P < 0.05). In addition, OTZ was found to marginally reduce the arecoline-induced IL-6 expression by about 1.7-fold (P < 0.05).
  
  
  CONCLUSIONS
  Taken together, these results suggest that IL-6 expression is significantly upregulated in OSF fibroblasts in areca quid chewers and arecoline may be responsible for the enhanced IL-6 expression. In addition, the regulation of IL-6 expression induced by arecoline is critically dependent on the intracellular GSH concentrations.
authors.affiliation: Department of Pathology, Chung Shan Medical University Hospital, Taichung, Taiwan.
authors.forename: C-H
authors.initials: CH
authors.lastname: Tsai
authors.forename: S-F
authors.initials: SF
authors.lastname: Yang
authors.forename: Y-J
authors.initials: YJ
authors.lastname: Chen
authors.forename: S-C
authors.initials: SC
authors.lastname: Chu
authors.forename: Y-S
authors.initials: YS
authors.lastname: Hsieh
authors.forename: Y-C
authors.initials: YC
authors.lastname: Chang
mesh_terms: D001114:Areca; D001115:Arecoline / Q000633:toxicity*; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D005978:Glutathione / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism*; D008297:Male; D009914:Oral Submucous Fibrosis / Q000209:etiology / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011761:Pyrrolidonecarboxylic Acid; D012333:RNA, Messenger / Q000378:metabolism; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines; D015854:Up-Regulation
chemical_list: D015850:Interleukin-6; D012333:RNA, Messenger; D013844:Thiazoles; D053778:Thiazolidines; D001115:Arecoline; D019328:Buthionine Sulfoximine; D005978:Glutathione; D011761:Pyrrolidonecarboxylic Acid; C029536:2-oxothiazolidine-4-carboxylic acid