title: Upregulation of DAF (CD55) on orbital fibroblasts by cytokines. Differential effects of TNF-beta and TNF-alpha.
abstract: OBJECTIVE
  Decay accelerating factor (DAF) and membrane cofactor protein (MCP) are membrane complement regulators that protect self cells from deposition of autologous C3b on their surfaces. CD59, a third downstream regulator of the cascade, prevents the assembly on self cells of autologous membrane-attack complexes. All three proteins are highly expressed on corneal and conjunctival epithelia, and are present in lower levels on multiple intraocular and adnexal cell types. The purpose of this study was to determine whether, and if so, how DAF, MCP and CD59 expression by ocular and adnexyl cells is modulated by cytokines.
  
  
  METHODS
  Primary cultures of orbital fibroblasts and corneal epithelial cells were incubated with TNF-alpha, TNF-beta, TGF-beta1, IFN-gamma, MIF or blocking anti-MIF mABs and extracts of the cells quantitated for DAF, MCP and CD59 by two-site immunoradiometric assays. Where inductions occurred, the kinetics of the increases, the effect of combining cytokines, and the effect of protein kinase-C inhibition were studied.
  
  
  RESULTS
  DAF expression on orbital fibroblasts was upregulated 6.3-, 3.7- and 4.2-fold by TGF-beta1, TNF-beta and IFN-gamma, respectively, but that its expression on corneal epithelial cells was minimally affected. These same (or other) cytokines did not significantly upregulate MCP or CD59. The cytokine-induced upregulation of DAF expression on orbital fibroblasts requires 24 hr for IFN-gamma or 48 hr for TGF-beta1 or TNF-beta, is dependent on new protein synthesis, and does not involve protein kinase-C activation.
  
  
  CONCLUSIONS
  TGF-beta1-, TNF-beta- and IFN-gamma-mediated upregulation of DAF should serve to prevent complement-mediated injury to orbital fibroblasts in the course of ocular inflammation. The induction by TNF-beta rather than TNF-alpha contrasts with that on all other cell types studied.
authors.affiliation: Pathology Department, Case Western Reserve University, Cleveland, Ohio 44106, USA.
authors.forename: E T
authors.initials: ET
authors.lastname: Cocuzzi
authors.forename: D S
authors.initials: DS
authors.lastname: Bardenstein
authors.forename: A
authors.initials: A
authors.lastname: Stavitsky
authors.forename: N
authors.initials: N
authors.lastname: Sundarraj
authors.forename: M E
authors.initials: ME
authors.lastname: Medof
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D018958:CD55 Antigens / Q000378:metabolism*; D018957:CD59 Antigens / Q000378:metabolism; D002478:Cells, Cultured; D019573:Epithelium, Corneal / Q000187:drug effects / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D008233:Lymphotoxin-alpha / Q000494:pharmacology*; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins / Q000378:metabolism; D009915:Orbit / Q000166:cytology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D015703:Antigens, CD; C497857:CD46 protein, human; D018958:CD55 Antigens; D018957:CD59 Antigens; D008233:Lymphotoxin-alpha; D051916:Membrane Cofactor Protein; D008562:Membrane Glycoproteins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma