title: Pro-inflammatory and anti-angiogenic effects of bisphosphonates on human cultured retinal pigment epithelial cells.
abstract: OBJECTIVE
  Bisphosphonates have been shown to induce ocular inflammatory diseases such as uveitis and scleritis, while being protective against angiogenic diseases like neovascular age-related macular degeneration (AMD). Therefore, we studied the effects of bisphosphonates on primary culture of human fetal retinal pigment epithelium (hRPE), a cell type known to secrete both inflammatory and angiogenic factors. Alendronate and etidronate were selected for this experiment as they are members of the two structurally different classes of bisphosphonates.
  
  
  METHODS
  Primary cultures of hRPE were serum-starved for 24 h and then treated for 24 h with alendronate (0.0001, 0.1, 100 µM) or etidronate (0.01, 1 µM). Cell viability was measured using the MTT assay. Investigation of secreted cytokines induced by bisphosphonates was performed using a human cytokine 29-Plex Panel (Bio-Plex) array and the results were analysed with an analysis of variance (ANOVA).
  
  
  RESULTS
  Etidronate, at the lower concentration, significantly increased the expression of interleukin (IL)-6 (p=0.03) and IL-8 (p=0.04). At the higher concentration, etidronate significantly decreased the expression of granulocyte macrophage colony-stimulating factor (p=0.02) and basic fibroblast growth factor (bFGF) (p=0.02). Alendronate, at the highest concentration, significantly increased the expression of IL-8 (p=0.02) and decreased the expression of eotaxin (p=0.02). Alendronate also significantly decreased the expression of bFGF at all concentrations (p<0.05) and demonstrated a trend towards decreasing vascular endothelial growth factor expression at low concentration.
  
  
  CONCLUSIONS
  Alendronate and etidronate display dose dependent effects in hRPE cells. Alendronate and etidronate administration resulted in concentration dependent elevations in inflammatory cytokines. Furthermore, alendronate and etidronate administration resulted in reduced expression of a number of angiogenic factors. These findings may explain the increased incidence of ocular inflammation as well as the therapeutic effect on neovascular AMD which have been described with bisphosphonates.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Chris
authors.initials: C
authors.lastname: Or
authors.forename: Jing
authors.initials: J
authors.lastname: Cui
authors.forename: Joanne
authors.initials: J
authors.lastname: Matsubara
authors.forename: Farzin
authors.initials: F
authors.lastname: Forooghian
mesh_terms: D019386:Alendronate / Q000494:pharmacology*; D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D050071:Bone Density Conservation Agents / Q000494:pharmacology*; D002470:Cell Survival; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D012968:Etidronic Acid / Q000494:pharmacology*; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D015850:Interleukin-6 / Q000378:metabolism; D016209:Interleukin-8 / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000378:metabolism
chemical_list: D020533:Angiogenesis Inhibitors; D050071:Bone Density Conservation Agents; D016207:Cytokines; C508600:IL6 protein, human; D018836:Inflammation Mediators; D015850:Interleukin-6; D016209:Interleukin-8; D016222:Fibroblast Growth Factor 2; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D012968:Etidronic Acid; D019386:Alendronate
keywords: Angiogenesis; Biochemistry; Macula; Pharmacology; Retina