Age-related Macular Degeneration

BACKGROUND: Vision loss due to vascular disease of the retina is a leading cause of blindness in the world. Retinal angiomatous proliferation (RAP) is a subgroup of neovascular age-related macular degeneration (AMD), whereby abnormal blood vessels develop in the retina leading to debilitating vision loss and eventual blindness. The novel mouse strain, neoretinal vascularization 2 (NRV2), shows spontaneous fundus changes associated with abnormal neovascularization. The purpose of this study is to characterize the induction of pathologic angiogenesis in this mouse model. METHODS: The NRV2 mice were examined from postnatal day 12 (p12) to 3 months. The phenotypic changes within the retina were evaluated by fundus photography, fluorescein angiography, optical coherence tomography, and immunohistochemical and electron microscopic analysis. The pathological neovascularization was imaged by confocal microscopy and reconstructed using three-dimensional image analysis software. RESULTS: We found that NRV2 mice develop multifocal retinal depigmentation in the posterior fundus. Depigmented lesions developed vascular leakage observed by fluorescein angiography. The spontaneous angiogenesis arose from the retinal vascular plexus at postnatal day (p)15 and extended toward retinal pigment epithelium (RPE). By three months of age, histological analysis revealed encapsulation of the neovascular lesion by the RPE in the photoreceptor cell layer and subretinal space. CONCLUSIONS: The NRV2 mouse strain develops early neovascular lesions within the retina, which grow downward towards the RPE beginning at p15. This retinal neovascularization model mimics early stages of human retinal angiomatous proliferation (RAP) and will likely be a useful in elucidating targeted therapeutics for patients with ocular neovascular disease.

PURPOSE: Oxidative stress and metabolic dysregulation of the RPE have been implicated in AMD; however, the molecular regulation of RPE metabolism remains unclear. The transcriptional coactivator, peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α) is a powerful mediator of mitochondrial function. This study examines the ability of PGC-1α to regulate RPE metabolic program and oxidative stress response. METHODS: Primary human fetal RPE (hfRPE) and ARPE-19 were matured in vitro using standard culture conditions. Mitochondrial mass of RPE was measured using MitoTracker staining and citrate synthase activity. Expression of PGC-1 isoforms, RPE-specific genes, oxidative metabolism proteins, and antioxidant enzymes was analyzed by quantitative PCR and Western blot. Mitochondrial respiration and fatty-acid oxidation were monitored using the Seahorse extracellular flux analyzer. Expression of PGC-1α was increased using adenoviral delivery. ARPE-19 were exposed to hydrogen peroxide to induce oxidative stress. Reactive oxygen species were measured by CM-H2DCFDA fluorescence. Cell death was analyzed by LDH release. RESULTS: Maturation of ARPE-19 and hfRPE was associated with significant increase in mitochondrial mass, expression of oxidative phosphorylation (OXPHOS) genes, and PGC-1α gene expression. Overexpression of PGC-1α increased expression of OXPHOS and fatty-acid β-oxidation genes, ultimately leading to the potent induction of mitochondrial respiration and fatty-acid oxidation. PGC-1α gain of function also strongly induced numerous antioxidant genes and, importantly, protected RPE from oxidant-mediated cell death without altering RPE functions. CONCLUSIONS: This study provides important insights into the metabolic changes associated with RPE functional maturation and identifies PGC-1α as a potent driver of RPE mitochondrial function and antioxidant capacity.

PURPOSE: To assess the safety and tolerability of E10030 (Fovista; Ophthotech, New York, NY), a platelet-derived growth factor (PDGF) antagonist, when administered in combination with an anti-vascular endothelial growth factor (VEGF) agent, ranibizumab (Lucentis; Genentech, South San Francisco, CA) 0.5 mg, by intravitreal injection in participants with neovascular age-related macular degeneration (NVAMD). DESIGN: Prospective phase 1 clinical trial. PARTICIPANTS: A total of 23 participants diagnosed with NVAMD and aged 50 years or older were enrolled. METHODS: Part 1 included 15 participants. Three participants received a single intravitreal E10030 (0.03 mg) injection and were subsequently given intravitreal ranibizumab (0.5 mg) injections at weeks 2, 6, and 10. Twelve participants (3 per group) received E10030 (0.03, 0.3, 1.5, or 3.0 mg) in combination with ranibizumab (0.5 mg) at day 0, month 1, and month 2 in an ascending manner. In Part 2 (8 participants), E10030 (0.3, 1.5, or 3.0 mg) in combination with ranibizumab (0.5 mg) was injected at day 0, month 1, and month 2. MAIN OUTCOME MEASURES: Safety at week 12 was the primary outcome and included assessment of vital signs, laboratory tests, and serial eye examinations. Other safety metrics included assessment through week 24 of Early Treatment of Diabetic Retinopathy Study (ETDRS) visual acuity (VA) and biomarker changes evaluated by optical coherence tomography (OCT) and fluorescein angiography (FA). RESULTS: All doses of intravitreal E10030 administered in combination with ranibizumab were well tolerated. No dose-limiting toxicities or relevant safety events were noted at any dose level during the study. Investigators did not report adverse events related to E10030 or ranibizumab. Mean VA change was a gain of 14 letters, and 59% of participants gained ≥15 letters from baseline at week 12. On FA at week 12, there was an 85.5% mean reduction from baseline in choroidal neovascularization (CNV) size. On OCT at the week 12 visit, there was a mean decrease in center point thickness and central subfield thickness of 38.9% and 33.7%, respectively. CONCLUSIONS: Intravitreal E10030 administered at doses up to 3 mg in combination with ranibizumab was well tolerated without evidence of systemic or ocular toxicity in participants with NVAMD. The changes in both mean VA and imaging biomarkers suggest a favorable short-term safety profile for the combination therapy of E10030 and ranibizumab.

OBJECTIVES: To review the contribution of the Nurses' Health Study (NHS) to understanding the genetic and lifestyle factors that influence the risk of cataract, age-related macular degeneration, and glaucoma. METHODS: We performed a narrative review of the publications of the NHS between 1976 and 2016. RESULTS: The NHS has helped to elucidate the roles of genetics, lifestyle factors (e.g., cigarette smoking associated with cataract extraction and age-related macular degeneration), medical conditions (e.g., diabetes associated with cataract extraction and glaucoma), and dietary factors (e.g., greater carotenoid intake and lower glycemic diet associated with lower risk of age-related macular degeneration) in the etiology of degree and progression of lens opacities, cataract extraction, age-related macular degeneration, primary open-angle glaucoma, and exfoliation glaucoma. CONCLUSIONS: The findings from the NHS, combined with those of other studies, have provided compelling evidence to support public health recommendations for helping to prevent age-related eye diseases: abstinence from cigarette smoking, maintenance of healthy weight and diabetes prevention, and a healthy diet rich in fruits and vegetables.

PURPOSE: To evaluate the mechanism of tamoxifen-induced cell death in human cultured RPE cells, and to investigate concurrent cell death mechanisms including pyroptosis, apoptosis, and necroptosis. METHODS: Human RPE cells were cultured until confluence and treated with tamoxifen; cell death was measured by detecting LDH release. Tamoxifen-induced cell death was further confirmed by 7-aminoactinomycin D (7-AAD) and annexin V staining. Lysosomal destabilization was assessed using lysosomal-associated membrane protein-1 (LAMP-1) and acridine orange staining. The roles of lysosomal enzymes cathepsin B and L were examined by blocking their activity. Caspase activity was evaluated by caspase-1, -3, -8, and -9 specific inhibition. Cells were primed with IL-1α and treated with tamoxifen; mature IL-1β production was quantified via ELISA. Caspase activity was verified with the fluorochrome-labeled inhibitor of caspases (FLICA) probe specific for each caspase. Regulated cell necrosis or necroptosis was examined with 7-AAD and inhibition of receptor-interacting protein 1 (RIP1) kinase using necrostatin-1 (Nec-1). RESULTS: Cell death occurred within 2 hours of tamoxifen treatment of confluent RPE cells and was accompanied by lysosomal membrane permeabilization. Blockade of cathepsin B and L activity led to a significant decrease in cell death, indicating that lysosomal destabilization and cathepsin release occur prior to regulated cell death. Tamoxifen-induced toxicity was shown to occur through both caspase-dependent and caspase-independent cell death pathways. Treatment of RPE cells with caspase inhibitors and Nec-1 resulted in a near complete rescue from cell death. CONCLUSIONS: Tamoxifen-induced cell death occurs through concurrent regulated cell death mechanisms. Simultaneous inhibition of caspase-dependent and caspase-independent cell death pathways is required to protect cells from tamoxifen. Inhibition of upstream activators, such as the cathepsins, may represent a novel approach to block multiple cell death pathways.