title: Factor Xa and thrombin stimulate proinflammatory and profibrotic mediator production by retinal pigment epithelial cells: a role in vitreoretinal disorders?
abstract: BACKGROUND
  Vitreoretinal disorders, including proliferative vitreoretinopathy (PVR), proliferative diabetic retinopathy (PDR) and exudative age-related macular degeneration (AMD), are a major cause of visual impairment worldwide and can lead to blindness when untreated. Loss of blood-retinal barrier (BRB) integrity associated with vitreoretinal fibrin deposition, inflammation, fibrosis and neovascularization contribute to the pathophysiological processes in these disorders. Retinal pigment epithelial (RPE) cells are well recognized to contribute to vitreoretinal inflammation/fibrosis and are likely to encounter contact with coagulation factor upon loss of BRB integrity.
  
  
  METHODS
  An extensive study was performed in which we examined the effect of factor Xa and thrombin on the production of a broad panel of cytokines/chemokines and growth factors by RPE cells. For this purpose we used the ARPE-19 cell line as well as primary RPE cells, a glass slide based array that allows simultaneous detection of 120 cytokines/chemokines and growth factors, ELISA and real-time-quantitative PCR. The involved signaling cascade was examined using specific inhibitors for protease activated receptor (PAR)1, PAR2 and nuclear factor kappa-B (NF-κB).
  
  
  RESULTS
  Factor Xa and thrombin regulated the production of cytokines and growth factors (including GM-CSF, IL-6, IL-8, MCP-3, PDGF-AA, PDGF-BB, TIMP-1 and TGF-α) that fit well in the pathobiology of vitreoretinal disease. Blocking studies revealed that the effects were mediated via PAR1 induced NF-κB activation.
  
  
  CONCLUSIONS
  Our findings suggest that factor Xa and thrombin can drive vitreoretinal inflammation and fibrosis and should be considered as treatment targets in vitreoretinal disorders such as PVR, PDR and AMD.
authors.affiliation: The Rotterdam Eye Hospital, Rotterdam, The Netherlands. j.bastiaans@erasmusmc.nl
authors.forename: Jeroen
authors.initials: J
authors.lastname: Bastiaans
authors.forename: Jan C
authors.initials: JC
authors.lastname: van Meurs
authors.forename: Conny
authors.initials: C
authors.lastname: van Holten-Neelen
authors.forename: Marja Smits-Te
authors.initials: MS
authors.lastname: Nijenhuis
authors.forename: Marion J
authors.initials: MJ
authors.lastname: Kolijn-Couwenberg
authors.forename: P Martin
authors.initials: PM
authors.lastname: van Hagen
authors.forename: Robert W A M
authors.initials: RW
authors.lastname: Kuijpers
authors.forename: Herbert
authors.initials: H
authors.lastname: Hooijkaas
authors.forename: Willem A
authors.initials: WA
authors.lastname: Dik
mesh_terms: D002460:Cell Line; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D003930:Diabetic Retinopathy / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D015951:Factor Xa / Q000494:pharmacology*; D005355:Fibrosis; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008268:Macular Degeneration / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D044463:Receptor, PAR-1 / Q000378:metabolism; D012164:Retinal Diseases / Q000378:metabolism*; D055213:Retinal Pigment Epithelium / Q000187:drug effects* / Q000378:metabolism; D013917:Thrombin / Q000494:pharmacology*; D018630:Vitreoretinopathy, Proliferative / Q000378:metabolism; D010975:Platelet Aggregation Inhibitors
chemical_list: D016207:Cytokines; D004791:Enzyme Inhibitors; D036341:Intercellular Signaling Peptides and Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; D044463:Receptor, PAR-1; D013917:Thrombin; D015951:Factor Xa; D010975:Platelet Aggregation Inhibitors