title: TNF-α-induced ICAM-1 expression and monocyte adhesion in human RPE cells is mediated in part through autocrine VEGF stimulation.
abstract: OBJECTIVE
  Local inflammation at the RPE cell layer is associated with inflammatory cell migration and secretion of proinflammatory cytokines such as tumor necrosis factor (TNF)-α. TNF-α upregulates intercellular adhesion molecule (ICAM)-1 expression on the RPE, which allows lymphocyte function-associated antigen-1 (LFA-1) to bind on leukocytes that contribute to leukocyte adhesion at sites of inflammation. Vascular endothelial growth factor (VEGF)-A(165)b is generated by alternative splicing of VEGF-A in the terminal exon, exon 8. VEGF-A(165)b is cytoprotective and antiangiogenic, but its effects on inflammation have not yet been elucidated. Therefore, we tested the hypothesis that VEGF-A(165)b regulates TNF-α-induced ICAM-1 expression and monocyte adhesion in RPE cells.
  
  
  METHODS
  Primary RPE cells were pretreated with TNF-α alone, VEGF-A(165)b alone, VEGF-A(165)b with anti-VEGF-A(165)b, or the VEGFR-2 inhibitor ZM323881 before exposure to TNF-α for 24 h. Western blotting and monocyte adhesion assays were performed.
  
  
  RESULTS
  VEGF-A(165)b and ZM323881 inhibited TNF-α-induced upregulation of ICAM-1 in RPE cells. The effect of VEGF-A(165)b was neutralized by an antibody to VEGF-A(165)b. VEGF-A(165)b ameliorated TNF-α-induced monocyte-RPE adhesion.
  
  
  CONCLUSIONS
  These findings indicate that VEGF-A(165)b inhibits TNF-α-mediated upregulation of ICAM-1 expression and increases monocyte-RPE cell adhesion, suggesting an anti-inflammatory property of VEGF-A(165)b in the eye.
authors.affiliation: Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand ; Microvascular Research Laboratories, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Bristol, UK.
authors.forename: Peeradech
authors.initials: P
authors.lastname: Thichanpiang
authors.affiliation: Microvascular Research Laboratories, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Bristol, UK.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Harper
authors.affiliation: Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Kanokpan
authors.initials: K
authors.lastname: Wongprasert
authors.affiliation: Microvascular Research Laboratories, Department of Physiology and Pharmacology, School of Veterinary Sciences, University of Bristol, Bristol, UK ; Cancer Biology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Queen's Medical Centre, Nottingham, UK.
authors.forename: David O
authors.initials: DO
authors.lastname: Bates
mesh_terms: D019898:Autocrine Communication / Q000187:drug effects*; D002448:Cell Adhesion / Q000187:drug effects; D002452:Cell Count; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D018919:Neovascularization, Physiologic / Q000187:drug effects; D020033:Protein Isoforms / Q000378:metabolism; D055213:Retinal Pigment Epithelium / Q000166:cytology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism*
chemical_list: D020033:Protein Isoforms; D014409:Tumor Necrosis Factor-alpha; D042461:Vascular Endothelial Growth Factor A; D018799:Intercellular Adhesion Molecule-1