Dabigatran inhibits intravitreal thrombin activity

PURPOSE: Proliferative vitreoretinopathy (PVR) is a vitreoretinal disorder in which retinal pigment epithelial (RPE) cell activation contributes to both formation of fibrotic retinal membranes and inflammation. Vitreous of patients with PVR contains increased thrombin activity which induces profibrotic and proinflammatory programs in RPE cells. Inhibition of intravitreal thrombin activity may thus represent a therapeutic option for PVR. In this study, we examined the capacity of the clinically available direct thrombin inhibitor dabigatran to inhibit thrombin activity in vitreous fluids.

METHODS: ARPE-19 cells were cultured with the following: (i) thrombin, (ii) vitreous without thrombin activity and (iii) vitreous with elevated thrombin activity (PVR samples and thrombin spiked vitreous) either in the presence or absence of dabigatran (range: 10-5 to 10-7 M). Subsequently, CCL2, CXCL8, GMCSF, IL6 and PDGFB mRNA expression levels were determined by RQ-PCR and protein levels of 27 cytokines, chemokines and growth factors were detected in culture supernatants using a multiplex approach. In addition, the capacity of vitreous fluids obtained from patients after oral dabigatran intake was tested in an in vitro thrombin activity assay.

RESULTS: Thrombin and vitreous fluids containing thrombin activity induced CCL2, CXCL8, GM-CSF, IL-6 and PDGF-BB expression by ARPE-19 cells, which was inhibited by dabigatran. In addition, dabigatran that reached the vitreous after repeated oral intake did inhibit thrombin activity in the in vitro activity assay.

CONCLUSION: Proliferative vitreoretinopathy (PVR) is associated with increased intravitreal thrombin activity that activates profibrotic and proinflammatory pathways in RPE cells. Our findings provide evidence that this activation pathway can potentially be inhibited by dabigatran.