title: The protective effect of antioxidants on orbital fibroblasts from patients with Graves' ophthalmopathy in response to oxidative stress.
abstract: OBJECTIVE
  To investigate the biphasic effects of hydrogen peroxide (H2O2) on the orbital fibroblasts of patients with Graves' ophthalmopathy (GO) and the relation to antioxidants and proinflammatory cytokines.
  
  
  METHODS
  Proliferation of cultured orbital fibroblasts from patients with GO and normal controls was evaluated in response to various concentrations of H2O2. The effect of low concentrations of H2O2 (6.25 μM) on the cellular proliferation and induction of intracellular proinflammatory cytokines, and reactive oxygen species of orbital fibroblasts were assessed. Protective effects of N-acetylcysteine and vitamin C on GO fibroblasts in response to 6.25 μM H2O2 stimulation were also investigated.
  
  
  RESULTS
  When the GO fibroblasts were exposed to H2O2 at a concentration of 50 μM or above, significant cytotoxicity was observed. In contrast, lower concentrations of H2O2 (3.125-25 μM) increased the survival of GO fibroblasts with the peak cellular proliferation at 6.25 μM H2O2. However, this biphasic effect of H2O2 on the viability of orbital fibroblasts was not found in normal controls. In addition, 6.25 μM H2O2 led to significant elevation of the levels of transforming growth factor, beta 1, interleukin-1β, and superoxide anion in GO fibroblasts, but no significant change in the normal controls. Pretreatment with N-acetylcysteine or vitamin C reversed the enhanced proliferation capacity and the induction of transforming growth factor, beta 1, interleukin-1β and superoxide anion of GO fibroblasts in response to 6.25 μM H2O2.
  
  
  CONCLUSIONS
  These findings revealed the biphasic effect of H2O2 on cellular proliferation of GO orbital fibroblasts. Importantly, a low level of H2O2 can stimulate proliferation of GO orbital fibroblasts and induce the production of proinflammatory cytokines, which can be inhibited by pretreatment with antioxidants. This provides a theoretical basis for the rational use of antioxidant in treating GO at an early stage.
authors.affiliation: Department of Ophthalmology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chieh-Chih
authors.initials: CC
authors.lastname: Tsai
authors.forename: Shi-Bei
authors.initials: SB
authors.lastname: Wu
authors.forename: Shu-Ching
authors.initials: SC
authors.lastname: Kao
authors.forename: Hui-Chuan
authors.initials: HC
authors.lastname: Kau
authors.forename: Fenq-Lih
authors.initials: FL
authors.lastname: Lee
authors.forename: Yau-Huei
authors.initials: YH
authors.lastname: Wei
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology / Q000627:therapeutic use; D000328:Adult; D000975:Antioxidants / Q000494:pharmacology / Q000627:therapeutic use*; D001205:Ascorbic Acid / Q000494:pharmacology / Q000627:therapeutic use; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D049970:Graves Ophthalmopathy / Q000188:drug therapy* / Q000473:pathology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D053583:Interleukin-1beta / Q000378:metabolism; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009915:Orbit / Q000473:pathology*; D018384:Oxidative Stress / Q000187:drug effects; D020011:Protective Agents / Q000494:pharmacology / Q000627:therapeutic use*; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D000975:Antioxidants; D053583:Interleukin-1beta; D020011:Protective Agents; D016212:Transforming Growth Factor beta; D006861:Hydrogen Peroxide; D001205:Ascorbic Acid; D000111:Acetylcysteine