: The bone morphogenetic protein (BMP) family of proteins has a multitude of roles throughout the body. It plays important roles in development and in the adult vascular endothelium, by modulating the angiogenic response. The endothelial-specific receptor BMP receptor Alk1 is of particular importance in the proper remodeling of the vasculature and its ligand BMP9 has been shown to be a potent inhibitor of neovascularization. Dysregulated BMP signaling has been linked to multiple vascular diseases and can lead to the abnormal angiogenesis. We therefore investigated the role of BMP9/Alk1 signaling in retinal angiogenesis, and its therapeutic implications for vascular pathologies of the eye.

Background: Sight-threatening diabetic macular edema (DME) is caused by increased microvascular permeability. While few direct vascular targeting strategies are available, VEGF pathway inhibition has shown to be effective in reducing retinal vascular leakage but is associated with non-negligible side effects. Thus, more options are needed. Vascular specific Activin-like kinase receptor type I (ALK1) pathway and its circulating ligand Bone morphogenetic protein-9 (BMP9) is known for its potent quiescent and stabilizing effect on the vasculature. However, little is known about this pathway in the context of microvascular permeability associated with diabetes. We hypothesize that BMP9/ALK1 pathway is inhibited in diabetic (DB) retinas leading to vascular destabilization and leakage and that its activation could re-establish proper vascular endothelial barrier functions (EBF).

Background: To determine patient-reported vision-related quality of life (VR-QoL) following Boston type I keratoprosthesis (BI-KPro) surgery and its association with postoperative best-corrected visual acuity (BCVA).

Background: Metabolic stress has been proposed to contribute to neuronal damage in glaucoma, but the mechanism driving this response is not understood. The adenosine monophosphate-activated protein kinase (AMPK) is a master regulator of energy homeostasis that becomes active at the onset of energy stress. AMPK is a potent inhibitor of the mammalian target of rapamycin complex 1 (mTORC1), which we showed is essential for the maintenance of retinal ganglion cell (RGC) dendrites, synapses, and survival. Here, we tested the hypothesis that AMPK is an early mediator of metabolic stress in glaucoma.

Background: Age-related macular degeneration (AMD) is the most suspected cause of vision loss in the elderly. Given the considerable evidence, oxidative stress is thought to be a primary contributing factor to AMD. Retinal pigment epithelium (RPE) could be detrimentally compromised by oxidative stress along which blebs called retinal microparticles (RMPs) start to shed. In continue these particles would be taken by retina, causing RPE senescence, dysfunction and ultimately cell death. Along with the intracellular damages, accumulative deposit of microparticles in subretinal region can cause most known histological hallmark of dry AMD namely drusen. Based on our preliminary study, of 20 present miRNAs, Let-7f is the most abundant microRNAs in RMPs. As the accused substrate of RMPs through which retina function is compromised has yet to be well understood, we aimed to investigate pathophysiological role of let-7f and specific signaling triggered in RPE dysfunction. In brief, the principal objective is to further understand how RMPs implicate in RPE dysfunction. Methods: By oxidative stress inducing, RMPs were isolated from cultured ARPE-19 cells. We considered the effect of RMPs on ARPE-19 cells viability using MTT assay. In addition, to see whether RMPs effect could be ascribed to let-7f, ARPE-19 cells were transfected by carrier containing miRNA Let-7f. These transfected cells were then subjected senescence (β-galactosidase) and cell cycle assay to explore the molecular events responsible for Let-7f induced RPE cell dysfunction. Results: Regarding result we found that RMPs adversely affected RPE cell growth and resulted in significant decrease (≥30%) in cell viability. Let-7f-treated cells also revealed considerable increases of the senescence-associated β-galactosidase activity. Alongside RMPs impact, let-7f treatment group also showed similar result in cell growth. Conclusions: To the best of our knowledge, RPE cells uptake microparticles derived from oxidative-injured retinal cells, deteriorating integrity of vision compartments. Not only these finding would suggest that RMP’s impression likely corresponds to the miRNA let-7f, but introduce Let-7f as a mediator exacerbating the oxidative damages to RPE cells. This undesirable interplay is followed probably by dry AMD. Taken together, it seems by finding involved downstream pathways under RMPs pathogenesis, we can inhibit AMD disease in the early stage as well. In this line, we plan to investigate consecutive effect of RMP-associated miRNA inhibition in oxidative damage of retinal pigment epithelium.

: Disorders of lipid metabolism and macrophage function have been implicated in tissue aging and in diseases such as age-related macular degeneration (AMD). Genetic studies and expression profiling have identified widespread abnormalities in cholesterol metabolism in the aging macrophage. In addition, the molecular pathways that regulate the transition from aging to disease have not been elucidated. The current status regarding the mechanisms that regulate macrophage aging and the molecular mechanisms of transition to disease in the context of AMD will be presented with a special focus on factors that influence pathologic angiogenesis and neurodegeneration.

Background: In glaucoma and after an ischemic injury of the retina, excessive activation of N-Methyl-D-Aspartate receptors, a type of glutamatergic receptors, induces the death of retinal ganglion cells and an irreversible vision loss. The painless loss of retinal cells does not allow for a swift diagnostic and treatment of retinal damages. There is no efficient therapy to improve retinal functions in this case. In order to develop new therapeutic approaches for retinal injury, we propose, in this study, to stimulate neuronal plasticity of the visual system by neutralising the glial protein, Nogo-A. The inhibitory action of this protein on axonal regeneration is well known in spinal cord injuries but not in the visual system. We thus studied the function of Nogo-A in vision recovery in mice. Methods: Nogo-A activities were chronically blocked by deleting its gene in KO mice and acutely, by intravitreal injections of an antibody known as 11C7. Inner retina lesions were done by injection of 0.5 or 5 nmol of NMDA in the vitreous humor. A PBS buffer was administered in control animals. The visual system functions were accessed with an optokinetic test in awake mice, by electroretinography (ERG) in the eye and visual evoked potentials in the visual cortex. Cell survival of retinal ganglion cells, amacrine and bipolar cells was evaluated on histological sections by immunofluorescence. Changes in expression of Nogo-A, its receptors and neuronal plasticity associated molecules were observed by Western blot and q-PCR. Results: At NMDA doses of ≤0.5 nmol, Nogo-A KO mice show a recovery of optokinetic responses much faster than in WT mice. Surprisingly, a single injection of the antibody, 11C7 was sufficient to improve VEPs of NMDA injured animals as compared to control antibody. Furthermore, ERGs showed that a dose of 0.5 nmol induced retinal lesions limited to the ganglion cell layer, with significant changes to the VEPs but without influencing photoreceptors and inner nuclear layer cells functions. However, 5 nmol of NMDA affected the survival of inner nuclear layer cells and reduced by ~50% their activity. Conclusions: Our results show that the neutralisation of Nogo-A can improve visual functions after injury to the inner retina. Inhibition of Nogo-A could thus be an efficient way to treat pathologies like glaucoma.

Background: A transient reduction in intraocular pressure (IOP) after an aerobic exercise is found time and again across studies in literature. It has been suggested that systemic dehydration could be a possible mechanism driving these hypotensive effects of exercise. However, IOP reduction never had been examine in hyper versus hypo-hydration conditions for a same group of participants. The purpose of this study is to examine the influence of hyper and hypo hydration conditions on exercise-induced fluctuations in intraocular pressure.

Background: Overexpression of inducible nitric oxide synthase (iNOS) has been reported in diabetic retinopathy (DR). The kinin B1 receptor (B1R) is also overexpressed in DR, and can stimulate iNOS via Gαi/ERK/MAPK pathway. We previously showed that the topical administration of a B1R antagonist, LF22-0542, significantly reduces leukocyte infiltration, increased vascular permeability and overexpression of several inflammatory mediators, including iNOS in DR. Thus, the aim of this study was to determine whether the pro-inflammatory effects of B1R are attributed to oxidative stress caused by the activation of iNOS pathway in order to identify new therapeutic targets for the treatment of DR. iNOS and B1R being absent in the normal retina, their inhibition is unlikely to result in undesirable side effects. The approach will be no invasive by eye application of drops. Methods: Diabetes was induced in male Wistar rats (200–230 g) by a single intraperitoneal injection of streptozotocin (STZ, 65 mg/kg b.w). One week later, rats were randomly divided into four groups (N=5) and treated for one week as follows: Gr 1: control rats treated with the selective iNOS inhibitor (1,400 W, 0.06 µM twice a day by eye-drops ×7 days), Gr 2, STZ-diabetic rats treated with 1,400 W, Gr 3: control rats received a selective B1R agonist [Sar (D-Phe8)-des-Arg9-BK, 100 µg twice a week] by intravitreal injections (itrv) and treated with 1,400 W, Gr 4: STZ-diabetic rats + B1R agonist +1,400 W. At the end of treatment and two weeks post-STZ, three series of experiments were carried out to measure vascular permeability (by Evans blue dye method) and the expression of vasoactive and inflammatory mediators, including iNOS, VEGF-A, VEGF-R2, IL-1β, Cox-2, TNF-α, bradykinin 1 and 2 receptors and carboxypeptidase M/kininase 1 (by Western Blotting and qRT-PCR). The nitrosative stress (nitrosylation of proteins) was also assessed by Western Blotting. One-way Anova test with Bonferroni post hoc was used for statistical analysis. Results: STZ-diabetic rats showed a significant increase in retinal vascular permeability (22.8 µg/g Evans blue dye per g of fresh retinas, P=0.016) compared with control rats and control treated rats (17.2 and 16.8 µg/g respectively). The injections of B1R agonist amplified the increase of vascular permeability which was normalized by the 1,400 W. The overexpression of inflammatory markers was also normalized by the 1,400 W in STZ-diabetic rats received or not the B1R agonist. Conclusions: These results support a contribution of iNOS in the deleterious effects of B1R in this model of diabetic retinopathy. Hence, iNOS inhibition by ocular application of 1,400 W may represent a promising and non-invasive therapeutic approach in the treatment of diabetic retinopathy.

Abstract: Ocular vessel networks develop in a highly stereotyped fashion. Abnormal ocular angiogenesis is associated with major diseases including age-related macular degeneration and diabetic retinopathy. Better understanding of mechanisms driving angiogenesis is expected to uncover novel targets to prevent vision loss. Capillary growth is driven by endothelial tip cells, which are selected by dynamic interplay between VEGF, Notch and BMP signaling, with VEGF acting as a positive regulator, and Notch and the BMP receptor Alk1 acting as negative regulators of tip cell formation. The concerted interplay between these molecules ensures that appropriate tip cell numbers leading new vessel branches are formed. In addition, guidance receptors including Neuropilins and Roundabout receptors contribute to vascular patterning by regulating VEGF and BMP signaling. Possibilities to target these pathways during pathological ocular neovascularization will be discussed.