Background: Decrease of ocular blood flow has been linked to the pathogenesis of ocular diseases such as glaucoma and age-related macular degeneration. Current methods that measure the pulsatile blood flow have major limitations, including the assumption that ocular rigidity is the same in all eyes. Our group has recently developed a new method to measure the pulsatile choroidal volume change by direct visualization of the choroid with OCT imaging and automated segmentation. Our goal in this study is to describe the distribution of PCBF in a healthy Caucasian population.
Methods: Fifty-one subjects were recruited from the Maisonneuve-Rosemont Hospital Ophthalmology Clinic and underwent PCBF measurement in one eye. The distribution of PCBF in healthy eyes was assessed.
Results: The distribution of PCBF among the healthy eyes was found to be 3.94±1.70 μL with this technique.
Conclusions: This study demonstrates the normal range of PCBF values obtained in a healthy Caucasian population. This technique could be used for further investigation of choroid pulsatility and to study glaucoma pathophysiology.
Background: Retinal pigment epithelium (RPE) is vital for the homeostasis of the subretina including photoreceptors and choroid. Interestingly, our previous results suggested that the recently discovered lactate receptor GPR81 is abundantly expressed in RPE. To date, only one previous study has shown that activating GPR81 could enhance DNA repair by activating HDAC1. Consequently, we investigated whether GPR81 exhibits epigenetic modification in the subretina by using GPR81?/? mice.
Methods: GPR81?/? mice and wide type littermates were generated on a background of C57BL/6J mice. The thicknesses of their choroid were evaluated by immunohistochemistry. Meanwhile, Q-PCR, western blot and choroid sprout assay were performed. In vitro, primary retinal pigment epithelium (pRPE) cells were isolated from mice, and cultured for treatments.
Results: The thickness of choroid was reduced in GPR81?/? mice compared to GPR81+/+ mice, suggesting that GPR81 is important for the integrity of choroid. In the choroid sprout assay, lactate treated RPE/choroid complex showed a significant increase in angiogenesis compared to controls while lactate treated KO RPE/choroid complex showed no difference compared to their controls. For Q-PCR, most of the genes screened elevated their expression in GPR81?/? mice compared to WT mice, suggesting epigenetic modification may exist, which were confirmed by histone acetylation and HDACs activity assay.
Conclusions: Taking together, the lactate receptor GPR81 in RPE is very important for maintaining homeostasis of the subretina. This novel discovery sheds new light on the relationship between metabolism and epigenetic modification.
Background: We investigated the role of beta-adrenergic receptor (B-AR) on choroidal neovascularization (CNV) in an animal model of age-related macular degeneration in mice.
Methods: The angiogenic effect of the B-AR was evaluated in retinal pigment epithelium (RPE)-choroid explants from C57Bl6 mice stimulated with propranolol or isoproterenol (10 μM) (respectively antagonist and agonist of the B-AR) during 24 h. Conversely, a classic choroidal neovascularization (CNV) model induced by laser burn in C57Bl6 mice (8 weeks) was used to assess the anti-angiogenic effect of propranolol. In this experiment, mice were treated with intraperitoneal propranolol (6 mg/kg/d) or vehicle (saline solution) daily for 10 days, starting on day 4 after laser burn and until sacrifice (day 14). Immunostaining analysis on retinal flatmounts and cryosections were performed to determine the surface of CNV, the distribution of B-AR and the number and morphology of microglia/macrophages associated with CNV. To explore if the antiangiogenic effect of propranolol involved the modulation of the inflammatory microenvironment associated with CNV, we used RPE primary cells, J774 macrophages cell line and polarized M1 and M2 bone marrow-derived macrophage (BMDM). Choroidal explants treated with conditioned media (CM) from J774 or polarized M1/M2 BMDM pre-treated with propranolol to confirm the anti-angiogenic effect of propranolol. Expression of angiogenic factors was evaluated by RT PCR and Elisa.
Results: The expression and distribution of the B-1, B-2 and B-3 adrenergic receptors were localized in the choroid and RPE cells. The stimulation of RPE-choroid explants with isoproterenol increased CNV compared to vehicle, while propranolol decreased CNV. In vivo, propranolol inhibited significantly the levels of VEGF and CNV growth in laser burn model compared to the vehicle. Additionally, the treatment with propranolol decremented the number of activated (amoeboid shape) microglia/macrophages but surprisingly, the number of non-activated microglia/macrophages around the CNV was higher than with the vehicle treatment. In vitro, propranolol modulated the angiogenic balance in macrophages promoting anti-angiogenic factors expression, especially with M2 BMDM. CM from macrophages pre-treated with propranolol reduced CNV on choroidal explants.
Background: The neovascular aged-related macular degeneration (AMD) is the leading cause of legal blindness in the elderly. It is presently treated by anti-VEGF intravitreal injection in order to stop the neovascularization. In seeking of more efficient treatments to prevent retinal damage, it has been proposed that the kinin-kallikrein system (KKS), a key player in inflammation, could be involved in AMD etiology. However, the role of kinin receptors and their interaction with VEGF in AMD is poorly understood.
Methods: In order to address this question, choroidal neovascularization (CNV) was induced in the left eye of Long-Evans rat. After laser induction, anti-VEGF or IgG control were injected into the vitreal cavity. Gene expression was measured by qRT-PCR, retinal adherent leukocytes were labelled with FITC-Concanavalin A lectin, vascular leakage by the method of Evans blue and cellular localisation by immunohistochemistry.
Results: The number of labelled adherent leucocytes was significantly increased in laser-induced CNV compared to the control eye. This was significantly reversed by one single injection of anti-VEGF. Extravasation of Evans blue dye was significantly increased in laser-induced CNV eyes compared to control eyes and partially reversed by one single injection of anti-VEGF or by R954 treatment. The mRNA expression of inflammatory mediators was significantly increased in the retina of CNV rats. Immunodetection of B1R was significantly increased in CNV eyes. B1R immunolabeling was detected on endothelial and ganglion cells.
Conclusions: This study is the first to highlight an effect of the kinin/kallikrein system in a model of CNV that could be reduced by both anti-VEGF therapy and topically administered B1R antagonist R-954.
Background: Retinopathy of prematurity (ROP) is the major cause of blindness in children, mainly caused by the retinal neovascularization (NV). Mounting of evidences shown that macrophage plays a pivotal role in the regulation of angiogenesis in ROP. Numerous studies confirmed that the deletion of macrophage significantly reduce the neovascularized areas in the oxygen-induced retinopathy (OIR) model. We have been studied the effect of lymphocyte derived-microparticles (LMPs) over ten years. LMPs are extracellular vesicles derived from apoptotic human CEM T lymphocytes. Our previous studies demonstrated that LMPs possess strong anti-angiogenic effect. Recently we observed that LMPs are capable to switch the phenotype of macrophage, thus to suppress the choroidal neovascularization (CNV). However, the role of LMPs on macrophage in ROP has not been clarified. Thus, my project is to disclose the relationship between LMPs and macrophage in ROP using the OIR model. Hypothesis: LMPs may inhibit retinal NV in the OIR model through targeting at macrophage by affecting the migration of macrophage, thus to inhibit pathological angiogenesis in ROP.
Methods: Cell culture [RAW 264.7 and bone marrow-derived macrophage (BMDM)] for cell migration and viability assay. Generate the OIR model for in vivo detection of macrophage recruitment. Quantification of retinal NV, immunohistostaining of the macrophage in vivo, ex vivo retinal explants for cell migration and qPCR.
Results: LMPs do not affect RAW 264.7 and BMDM cell viability (P>0.05). LMPs significantly decrease the BMDM cell migration indirectly (P<0.05). I successfully generate the OIR model and confirm that more macrophages infiltrate during retinal angiogenesis with counting the F4/80 immunostaining in the retinal flat mount. LMPs exert inhibiting effect on retinal angiogenesis through decreasing the migration of macrophages in vivo.
Conclusions: LMPs have the negative effect on retinal angiogenesis via reducing the infiltrated macrophages to the neovascularized areas in the OIR model.
Background: The goal of this study was to engineer an epithelialized and endothelialized pigmented choroidal substitute using the self-assembly approach of tissue engineering.
Methods: Cells from human choroids were isolated and cultured. Culture purity was assessed using immunostaining (CD31, HMB45, vimentin, keratins 8/18). To engineer the choroid, fibroblasts were cultured in the presence of serum and ascorbic acid to promote extracellular matrix (ECM) assembly. Endothelial cells, melanocytes or RPE cells were separately seeded on the stromal substitutes. Choroidal substitutes were further characterized by histology, mass spectrometry, immunostaining, and compared to native human choroids.
Results: The technique used to isolate choroidal cells yielded pure cultures of fibroblasts, melanocytes and vascular endothelial cells. The stromal substitutes engineered using the self-assembly approach were composed of collagen (types I, VI, XII and XIV), proteoglycans (decorin, lumican) and other ECM proteins. Protein expression was confirmed using immunostaining. Endothelial cells spontaneously assembled into capillary-like structures and vascular networks when cocultured with fibroblast-containing ECM sheets.
Conclusions: This study shows that the self-assembly approach of tissue engineering can be used to reconstruct a choroid using native cells. This model represents a unique tool to better understand the crosstalk between the different choroidal cell types and cell-ECM interactions.
Abstract: Genetic studies have revealed that variants in genes that encode regulators of the complement system are major risk factors for the development of age-related macular degeneration (AMD). The biochemical consequences of the common polymorphism in complement factor H (Tyr402His) include increased formation of the membrane attack complex (MAC), which is deposited at the level of the inner choroid and choriocapillaris. Whereas the MAC is normally protective against foreign pathogens, it can also damage resident bystander cells when it is insufficiently regulated. Indeed, human maculas with early AMD show loss of endothelial cells in the choriocapillaris, the principal site of MAC activation. Modeling of MAC injury of choroidal endothelial cells in vitro reveals that these cells are susceptible to cell lysis by the MAC, and that unlysed cells alter their gene expression profile to undergo a pro-angiogenic phenotype that includes increased expression of matrix metalloproteinase-9. Strategies for protecting choriocapillaris endothelial cells from MAC-mediated lysis and for replacing lysed endothelial cells will be discussed.
Abstract: Pediatric neuro-ophthalmology is a subspecialty within neuro-ophthalmology. Pediatric neuro-ophthalmic diseases must be considered separate from their adult counterparts, due to the distinctive nature of the examination, clinical presentations, and management choices. This manuscript will highlight four common pediatric neuro-ophthalmic disorders by describing common clinical presentations, recommended management, and highlighting recent developments. Diseases discussed include pediatric idiopathic intracranial hypertension (IIH), pseudopapilledema, optic neuritis (ON) and optic pathway gliomas (OPG). The demographics, diagnosis and management of common pediatric neuro-ophthalmic disease require a working knowledge of the current research presented herein. Special attention should be placed on the differences between pediatric and adult entities such that children can be appropriately diagnosed and treated.
