title: The role of thrombin in proliferative vitreoretinopathy.
abstract: OBJECTIVE
  To determine the role of thrombin in the development of proliferative vitreoretinopathy (PVR).
  
  
  METHODS
  Vitreous was collected from patients undergoing a vitrectomy (macular holes and puckers, n = 11 [controls]; retinal detachment without PVR development following vitrectomy, n = 15 [RRD1]; retinal detachment with PVR development within 6 months after vitrectomy, n = 11 [RRD2]; and established PVR, n = 14 [PVR]). Thrombin activity in vitreous was determined using a thrombin-specific chromogenic substrate. ARPE-19 cells were stimulated with 8× diluted vitreous samples in the presence and absence of hirudin. The samples were analyzed at t = 0 and t = 24 hours for the presence of 27 cytokines/chemokines and growth factors using a multiplex approach. In comparable studies, ARPE-19 cells were stimulated for 2 hours, and mRNA expression levels for CCL2, CXCL8, GMCSF, IL6, and PDGFB were determined by real-time quantitative (RQ)-PCR.
  
  
  RESULTS
  Thrombin activity was significantly (P < 0.05) higher in vitreous of the PVR group compared to the other groups. Proliferative vitreoretinopathy vitreous stimulated the production of chemokine (C-C motif) ligand (CCL)2, chemokine (C-X-C motif) ligand (CXCL)8, granulocyte-macrophage colony-stimulating factor (GM-CSF), IL-6, and platelet-derived growth factor (PDGF)-BB by ARPE-19 to significantly (P < 0.05) higher levels than vitreous from the RRD1 and RRD2 groups. These effects of PVR vitreous were significantly (P < 0.05) reduced by hirudin. These data were confirmed by mRNA studies.
  
  
  CONCLUSIONS
  Thrombin activity is increased in vitreous of patients with established PVR and is involved in the activation of proinflammatory and profibrotic pathways in RPE cells. Inhibition of thrombin activity may therefore represent a potential treatment option for proliferative vitreoretinopathy.
authors.affiliation: Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Bastiaans
authors.affiliation: Department of Ophthalmology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands The Rotterdam Eye Hospital, Rotterdam, The Netherlands.
authors.forename: Jan C
authors.initials: JC
authors.lastname: van Meurs
authors.affiliation: The Rotterdam Eye Hospital, Rotterdam, The Netherlands.
authors.forename: Verena C
authors.initials: VC
authors.lastname: Mulder
authors.affiliation: Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
authors.forename: Nicole M A
authors.initials: NM
authors.lastname: Nagtzaam
authors.affiliation: Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
authors.forename: Marja
authors.initials: M
authors.lastname: Smits-te Nijenhuis
authors.affiliation: Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
authors.forename: Diana C M
authors.initials: DC
authors.lastname: Dufour-van den Goorbergh
authors.affiliation: Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands Department of Internal Medicine, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
authors.forename: P Martin
authors.initials: PM
authors.lastname: van Hagen
authors.affiliation: Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
authors.forename: Herbert
authors.initials: H
authors.lastname: Hooijkaas
authors.affiliation: Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands.
authors.forename: Willem A
authors.initials: WA
authors.lastname: Dik
mesh_terms: D000368:Aged; D002460:Cell Line; D016207:Cytokines / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012163:Retinal Detachment / Q000601:surgery; D012167:Retinal Perforations / Q000601:surgery; D055213:Retinal Pigment Epithelium / Q000378:metabolism; D013917:Thrombin / Q000502:physiology*; D014821:Vitrectomy; D018630:Vitreoretinopathy, Proliferative / Q000378:metabolism* / Q000601:surgery; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: D016207:Cytokines; D012333:RNA, Messenger; D013917:Thrombin
keywords: chemokines; cytokines; fibrosis; growth factors; inflammation; proliferative vitreoretinopathy (PVR); retinal pigment epithelium (RPE); rhegmatogenous retinal detachment (RRD); thrombin; vitreous