OBJECTIVE-Leukocyte adhesion in retinal microvasuculature substantially contributes to diabetic retinopathy. Involvement of the Rho/Rho kinase (ROCK) pathway in diabetic microvasculopathy and therapeutic potential of fasudil, a selective ROCK inhibitor, are investigated. RESEARCH DESIGN AND METHODS-Localization ofRhoA/ROCK and Rho activity were examined in retinal tissues of rats. Impact of intravitreal fasudil administration on retinal endothelial nitric oxide synthase (eNOS) and myosin phosphatase target protein (MYPT)-1 phosphorylation, intercellular adhesion molecule-1 (ICAM-1) expression, leukocyte adhesion, and endothelial damage in rat eyes were investigated. Adhesion of neutrophils from diabetic retinopathy patients or nondiabetic control subjects to cultured microvascular endothelial cells was quantified. The potential of fasudil for endothelial protection was investigated by measuring the number of adherent neutrophils and terminal transferase-mediated dUTP nick-end labeling-positive endothelial cells.RESULTS-RhoA and ROCK colocalized predominantly in retinal microvessels. Significant Rho activation was observed in retinas of diabetic rats. Intravitreal fasudil significantly increased eNOS phosphorylation, whereas it reduced MYPT-1 phosphorylation, ICAM-1 expression, leukocyte adhesion, and the number of damaged endothelium in retinas of diabetic rats. Neutrophils from diabetic retinopathy patients showed significantly higher adhesion to cultured endothelium and caused endothelial apoptosis, which was significantly reduced by fasudil. Blockade of the Fas-FasL interaction prevented endothelial apoptosis. The protective effect of fasudil on endothelial apoptosis was significantly reversed by N-nitro-L-arginine methyl ester, a NOS inhibitor, whereas neutrophil adhesion remained unaffected. CONCLUSIONS-The

Cicatricial contraction of preretinal fibrous membrane is a cause of severe vision loss in proliferative vitreoretinal diseases such as proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). TGF-␤ is overexpressed in the vitreous of patients with proliferative vitreoretinal diseases and is also detectable in the contractile membranes. Therefore, TGF-␤ is presumed to contribute to the cicatricial contraction of the membranes, however, the underlying mechanisms and TGF-␤'s importance among various other factors remain to be elucidated. Vitreous samples from PDR or PVR patients caused significantly larger contraction of hyalocyte-containing collagen gels, compared with nonproliferative controls. The contractile effect was strongly correlated with the vitreal concentration of activated TGF-␤2 (r ‫؍‬ 0.82, P < 0.0001). proliferative diabetic retinopathy ͉ proliferative vitreoretinopathy ͉ fibrosis ͉ wound healing

Hyalocytes might be one of the critical components of ERM mediating its contractile property through the effect of TGF-beta2 in the vitreous fluid.

OBJECTIVE-Despite tremendous progress in vitreoretinal surgery, certain postsurgical complications limit the success in the treatment of proliferative vitreoretinal diseases (PVDs), such as proliferative diabetic retinopathy (PDR) and proliferative vitreoretinopathy (PVR). One of the most significant complications is the cicatricial contraction of proliferative membranes, resulting in tractional retinal detachment and severe vision loss. Novel pharmaceutical approaches are thus urgently needed for the management of these vision-threatening diseases. In the current study, we investigated the inhibitory effects of statins on the progression of PVDs.RESEARCH DESIGN AND METHODS-Human vitreous concentrations of transforming growth factor-␤2 (TGF-␤2) were measured by enzyme-linked immunosorbent assay. TGF-␤2-and vitreous-dependent phosphorylation of myosin light chain (MLC), a downstream mediator of Rho-kinase pathway, and collagen gel contraction simulating cicatrical contraction were analyzed using cultured hyalocytes. Inhibitory effects of simvastatin on cicatrical contraction were assessed both in vitro and in vivo.RESULTS-Human vitreous concentrations of TGF-␤2 were significantly higher in the samples from patients with PVD compared with those without PVD. Simvastatin inhibited TGF-␤2-dependent MLC phosphorylation and gel contraction in a dose-and time-dependent manner and was capable of inhibiting translocation of Rho protein to the plasma membrane in the presence of TGF-␤2. Vitreous samples from patients with PVD enhanced MLC phosphorylation and gel contraction, whereas simvastatin almost completely inhibited these phenomena. Finally, intravitreal injection of simvastatin dose-dependently prevented the progression of diseased states in an in vivo model of PVR.CONCLUSIONS-Statins might have therapeutic potential in the prevention of PVDs.

ICG is toxic to retinal glial cells because it induces apoptosis, involving induction of the caspase cascade through p38 MAPK phosphorylation. In contrast, BBG does not cause apoptosis and thus could be a safer adjuvant during vitreoretinal surgery.