title: Inflammatory cytokines protect retinal pigment epithelial cells from oxidative stress-induced death.
abstract: OBJECTIVE
  To investigate the effects of inflammatory factors and oxidative stress on cell survival of the human retinal pigment epithelial (RPE) cell line, ARPE-19.
  
  
  METHODS
  Confluent RPE cells were treated with peripheral blood mononuclear cells-conditioned medium (PCM), H2O2, NaIO3, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, or combinations of these. Cell viability was determined by viability assays and by light microscopy. Effector molecules of cell death were investigated by immunofluorescence microscopy and flow cytometry. Microarrays were performed to screen for differential expression of anti-oxidative enzymes, and protein expression was validated by immunoblotting.
  
  
  RESULTS
  Viability of RPE cells was reduced by exposure to inflammatory agents (PCM, IFNγ+/-TNFα) or to oxidative agents (H2O2 or NaIO3). Unexpectedly, cells treated with either H2O2 or NaIO3 were partially protected from cell death by the addition of PCM. This protection was conferred, at least in part, by IFNγ and TNFα. Cell death induced by H2O2 or NaIO3 was preceded by mitochondrial dysfunction and by p62 upregulation, both of which were attenuated by PCM and/or by IFNγ+TNFα. RPE cells co-cultured with activated T cells, or treated with cytokines showed increased expression of anti-oxidative genes, with upregulation of superoxide dismutase 2 protein following PCM treatment.
  
  
  CONCLUSIONS
  Oxidative stress-induced cell death was reduced by concomitant inflammatory stress. This is likely due to the cytokine-mediated induction of the anti-oxidative stress response, upregulating protective anti-oxidant pathway(s). These findings suggest caution for the clinical use of anti-inflammatory agents in the management of immune-associated eye diseases such as age-related macular degeneration.
authors.affiliation: Eye Research Unit, Department of International Health, Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark. hjuel@sund.ku.dk
authors.forename: Helene B
authors.initials: HB
authors.lastname: Juel
authors.forename: Carsten
authors.initials: C
authors.lastname: Faber
authors.forename: Signe G
authors.initials: SG
authors.lastname: Svendsen
authors.forename: Abbe N
authors.initials: AN
authors.lastname: Vallejo
authors.forename: Mogens H
authors.initials: MH
authors.lastname: Nissen
mesh_terms: D000328:Adult; D001343:Autophagy / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D018920:Coculture Techniques; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016207:Cytokines / Q000494:pharmacology*; D019610:Cytoprotection / Q000187:drug effects*; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D018836:Inflammation Mediators / Q000494:pharmacology*; D007371:Interferon-gamma / Q000494:pharmacology; D007452:Iodates / Q000494:pharmacology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects*; D055213:Retinal Pigment Epithelium / Q000473:pathology*; D013482:Superoxide Dismutase / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics
chemical_list: D017077:Culture Media, Conditioned; D016207:Cytokines; D018836:Inflammation Mediators; D007452:Iodates; D016877:Oxidants; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; C032285:sodium iodate