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Jeroen Bastiaans, Jan C. van Meurs, Conny van Holten, Martin van Hagen, Hans Vingerling, Robert W. Kuijpers, Herbert Hooijkaas, Wim A. Dik; Factor Xa And Thrombin May Be Involved In The Regulation Of Inflammation And Fibrosis In Proliferative Vitreoretinopathy. Invest. Ophthalmol. Vis. Sci. 2012;53(14):896.
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© ARVO (1962-2015); The Authors (2016-present)
Proliferative vitreoretinopathy (PVR) is a difficult to treat inflammatory fibrotic disorder complicating retinal detachment. Understanding of the processes involved in PVR is incomplete. However, proliferation and secretion of cytokines and collagen by RPE cells are considered to be central in PVR development. Because breakdown of the outer blood-retinal barrier is one of the first events in PVR development we hypothesize that coagulation proteins induce pro-inflammatory and fibrotic changes in RPE and as such play an important role in PVR development.
ARPE-19 cells were stimulated with factor Xa (1 U/ml) or thrombin (5 U/ml). Supernatants were analyzed for the presence of 120 cytokines/chemokines/growth factors using a quantitative cytokine array. Changes observed for several of these factors were confirmed by RQ-PCR or ELISA. Involvement of protease-activated receptor (PAR) subtypes as well as NF-ΚB signaling was examined using specific antagonists and inhibitors. Migration and proliferation were measured in scratch and methylene blue based assays. Collagen and α-smooth muscle actin (αSMA) expression was detected via fluorescence microscopy.
Factor Xa and thrombin both dose-dependently induced IL-6 and IL-8 expression by RPE cells. Cytokine array results showed that factor Xa and thrombin induced expression of pro-inflammatory as well as pro-fibrotic mediators by RPE. Factor Xa or thrombin induced enhancement of pro-inflammatory (IL-6, IL-8, MCP-3, GM-CSF) or pro-fibrotic mediator (PDGF-AA, PDGF-BB, TGF-α and TIMP-1) production was confirmed by ELISA. Blocking studies revealed that these effects were mediated via PAR1 induced NF-ΚB activation. Scratch and proliferation assays showed induced migration and proliferation. Collagen and αSMA expression was also induced.
The coagulation cascade proteins factor Xa and thrombin stimulate the production of pro-inflammatory and pro-fibrotic mediators by RPE cells via PAR1 induced NF-ΚB activation. Additionally, migration, proliferation, myo-fibroblastic differentiation and collagen production were induced. These data demonstrate that factor Xa and thrombin may contribute to PVR-associated chamges in RPE cell behaviour.
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