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Age-related Macular Degeneration

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Ma J, Sun Y, López FJ, Adamson P, Kurali E, Lashkari K. Blockage of PI3K/mTOR Pathways Inhibits Laser-Induced Choroidal Neovascularization and Improves Outcomes Relative to VEGF-A Suppression Alone. Invest Ophthalmol Vis Sci 2016;57(7):3138-44.Abstract

PURPOSE: Choroidal neovascularization (CNV) is a major cause of visual loss with age-related macular degeneration (AMD). We evaluated whether blockade of phosphatidyl-inositol-3-kinase (PI3K) and the mammalian target of rapamycin (mTOR), by impairing VEGF-A and other growth factor receptors like platelet-derived growth factor (PDGF), would reduce laser-induced CNV in mice. METHODS: Choroidal neovascularization lesions were induced in C57BL/6 mice. Two groups of mice received oral GSK2126458 (3 mg/kg) or vehicle for 14 days following laser, whereas three groups were treated with GSK2126458 (6 μg/eye), aflibercept (2 μL/eye), or vehicle intravitreally on days 0 and 7 after laser. Vascular leakage was measured by fluorescein angiography (FA) on day 14. Choroidal neovascularization membranes were evaluated on choroidal flat mounts following FITC-dextran perfusion, as well as ED1 and isolectin B4 (IB4) immunohistochemistry. RESULTS: Oral and intravitreal (IVT) GSK2126458 reduced leakage and area of CNV lesions. Greater probability of leaking lesions (∼60%; P < 0.05) was observed in both vehicle groups. Fluorescein isothiocyanate-dextran-labeled total CNV burden area (total lesion area/eye) was reduced ∼67% (P < 0.05) and 35% (P = 0.0528) after oral and IVT GSK2126458 administration. GSK2126458 treatment reduced lesion size by ∼80% (P < 0.05) and 50% (P < 0.05) for oral and IVT control groups. Aflibercept did not alter lesion size (∼27% reduction). CONCLUSIONS: Phosphatidyl-inositol-3-kinase/mTOR is involved in laser-induced CNV angiogenic processes. GSK2126458 effectively reduces CNV size and leakage. Choroidal neovascularization size following IVT GSK2126458 was smaller than after oral administration. Therefore, inhibition of PI3K/mTOR pathways may be more effective due to blockade of action of multiple growth factors.

Marques JP, Pires J, Simão J, Marques M, Gil JQ, Laíns I, Alves D, Nunes S, Cachulo ML, Miller JB, Vavvas DG, Miller JW, Husain D, Silva R. Validation of RetmarkerAMD as a semiautomatic grading software for AMD. Eye (Lond) 2020;34(3):600-602.
Maurya M, Bora K, Blomfield AK, Pavlovich MC, Huang S, Liu C-H, Chen J. Oxidative stress in retinal pigment epithelium degeneration: from pathogenesis to therapeutic targets in dry age-related macular degeneration. Neural Regen Res 2023;18(10):2173-2181.Abstract
Age-related macular degeneration is a primary cause of blindness in the older adult population. Past decades of research in the pathophysiology of the disease have resulted in breakthroughs in the form of anti-vascular endothelial growth factor therapies against neovascular age-related macular degeneration; however, effective treatment is not yet available for geographical atrophy in dry age-related macular degeneration or for preventing the progression from early or mid to the late stage of age-related macular degeneration. Both clinical and experimental investigations involving human age-related macular degeneration retinas and animal models point towards the atrophic alterations in retinal pigment epithelium as a key feature in age-related macular degeneration progression. Retinal pigment epithelium cells are primarily responsible for cellular-structural maintenance and nutrition supply to keep photoreceptors healthy and functional. The retinal pigment epithelium constantly endures a highly oxidative environment that is balanced with a cascade of antioxidant enzyme systems regulated by nuclear factor erythroid-2-related factor 2 as a main redox sensing transcription factor. Aging and accumulated oxidative stress triggers retinal pigment epithelium dysfunction and eventually death. Exposure to both environmental and genetic factors aggravates oxidative stress damage in aging retinal pigment epithelium and accelerates retinal pigment epithelium degeneration in age-related macular degeneration pathophysiology. The present review summarizes the role of oxidative stress in retinal pigment epithelium degeneration, with potential impacts from both genetic and environmental factors in age-related macular degeneration development and progression. Potential strategies to counter retinal pigment epithelium damage and protect the retinal pigment epithelium through enhancing its antioxidant capacity are also discussed, focusing on existing antioxidant nutritional supplementation, and exploring nuclear factor erythroid-2-related factor 2 and its regulators including REV-ERBα as therapeutic targets to protect against age-related macular degeneration development and progression.
McHugh KJ, Li D, Wang JC, Kwark L, Loo J, Macha V, Farsiu S, Kim LA, Saint-Geniez M. Computational modeling of retinal hypoxia and photoreceptor degeneration in patients with age-related macular degeneration. PLoS One 2019;14(6):e0216215.Abstract
Although drusen have long been acknowledged as a primary hallmark of dry age-related macular degeneration (AMD) their role in the disease remains unclear. We hypothesize that drusen accumulation increases the barrier to metabolite transport ultimately resulting in photoreceptor cell death. To investigate this hypothesis, a computational model was developed to evaluate steady-state oxygen distribution in the retina. Optical coherence tomography images from fifteen AMD patients and six control subjects were segmented and translated into 3D in silico representations of retinal morphology. A finite element model was then used to determine the steady-state oxygen distribution throughout the retina for both generic and patient-specific retinal morphology. Oxygen levels were compared to the change in retinal thickness at a later time point to observe possible correlations. The generic finite element model of oxygen concentration in the retina agreed closely with both experimental measurements from literature and clinical observations, including the minimal pathological drusen size identified by AREDS (64 μm). Modeling oxygen distribution in the outer retina of AMD patients showed a substantially stronger correlation between hypoxia and future retinal thinning (Pearson correlation coefficient, r = 0.2162) than between drusen height and retinal thinning (r = 0.0303) indicating the potential value of this physiology-based approach. This study presents proof-of-concept for the potential utility of finite element modeling in evaluating retinal health and also suggests a potential link between transport and AMD pathogenesis. This strategy may prove useful as a prognostic tool for predicting the clinical risk of AMD progression.
Menon M, Mohammadi S, Davila-Velderrain J, Goods BA, Cadwell TD, Xing Y, Stemmer-Rachamimov A, Shalek AK, Love JC, Kellis M, Hafler BP. Single-cell transcriptomic atlas of the human retina identifies cell types associated with age-related macular degeneration. Nat Commun 2019;10(1):4902.Abstract
Genome-wide association studies (GWAS) have identified genetic variants associated with age-related macular degeneration (AMD), one of the leading causes of blindness in the elderly. However, it has been challenging to identify the cell types associated with AMD given the genetic complexity of the disease. Here we perform massively parallel single-cell RNA sequencing (scRNA-seq) of human retinas using two independent platforms, and report the first single-cell transcriptomic atlas of the human retina. Using a multi-resolution network-based analysis, we identify all major retinal cell types, and their corresponding gene expression signatures. Heterogeneity is observed within macroglia, suggesting that human retinal glia are more diverse than previously thought. Finally, GWAS-based enrichment analysis identifies glia, vascular cells, and cone photoreceptors to be associated with the risk of AMD. These data provide a detailed analysis of the human retina, and show how scRNA-seq can provide insight into cell types involved in complex, inflammatory genetic diseases.
Miller JW. Developing Therapies for Age-related Macular Degeneration: The Art and Science of Problem-solving: The 2018 Charles L. Schepens, MD, Lecture. Ophthalmol Retina 2019;3(10):900-909.Abstract
PURPOSE: To review the roles of analytic and innovative thought in advancing knowledge, using past examples in ophthalmology, and to explore potential strategies to improve our understanding of age-related macular degeneration (AMD) and develop new therapies. DESIGN: Presented as the 2018 Charles L. Schepens, MD, Lecture at the American Academy of Ophthalmology Retina Subspecialty Day, Chicago, Illinois, on October 26, 2018. PARTICIPANTS: None. METHODS: Review of published literature and sources on creativity and innovation. MAIN OUTCOME MEASURES: Recommendations for future AMD research. RESULTS: Innovative solutions to problems often seem intuitively obvious in hindsight. Yet, some problems seem impossible to solve. In the 1990s, AMD was a significant unmet need, with only destructive therapies for neovascular disease. This changed with the development of 2 therapies: (1) verteporfin photodynamic therapy (PDT) and (2) anti-vascular endothelial growth factor (VEGF) therapies, which are now administered to millions of people annually around the world. Now, we are frustrated by the lack of therapies for early and intermediate AMD and geographic atrophy. Photodynamic therapy and anti-VEGF drug development occurred through a combination of analytic thought and creative disruption through innovation. To get past our current impasse in understanding and treating AMD, we need to harness both analysis and innovation. We have many important building blocks in place-information on genetics, clinical findings, imaging, and histology-and have identified key pathways and potential therapeutic targets. Perhaps we need additional investigation, analysis, and integration to improve our understanding through work on structure/function and genotype/phenotype correlations and development of imaging and systemic biomarkers. We likely also need an innovative disruption. This innovation might be the concept that there are subtypes of early and intermediate AMD characterized by specific clinical phenotypes, genotype, functional characteristics, and biomarkers that are dependent on particular pathways and treatable with a specific agent. We need to encourage innovation in each of us within our research and clinical community. CONCLUSIONS: Although we have accumulated extensive knowledge about AMD, we are currently at an impasse in the development of new treatments. We need to continue the analytic process, but at the same time encourage innovative disruption to develop successful AMD therapies.
Miller JW. Age-related macular degeneration revisited--piecing the puzzle: the LXIX Edward Jackson memorial lecture. Am J Ophthalmol 2013;155(1):1-35.e13.Abstract
PURPOSE: To present the current understanding of age-related macular degeneration (AMD) pathogenesis, based on clinical evidence, epidemiologic data, histopathologic examination, and genetic data; to provide an update on current and emerging therapies; and to propose an integrated model of the pathogenesis of AMD. DESIGN: Review of published clinical and experimental studies. METHODS: Analysis and synthesis of clinical and experimental data. RESULTS: We are closer to a complete understanding of the pathogenesis of AMD, having progressed from clinical observations to epidemiologic observations and clinical pathologic correlation. More recently, modern genetic and genomic studies have facilitated the exploration of molecular pathways. It seems that AMD is a complex disease that results from the interaction of genetic susceptibility with aging and environmental factors. Disease progression also seems to be driven by a combination of genetic and environmental factors. CONCLUSIONS: Therapies based on pathophysiologic features have changed the paradigm for treating neovascular AMD. With improved understanding of the underlying genetic susceptibility, we can identify targets to halt early disease and to prevent progression and vision loss.
Miyake M, Yamashiro K, Tamura H, Kumagai K, Saito M, Sugahara-Kuroda M, Yoshikawa M, Oishi M, Akagi-Kurashige Y, Nakata I, Nakanishi H, Gotoh N, Oishi A, Matsuda F, Yamada R, Khor C-C, Kurimoto Y, Sekiryu T, Tsujikawa A, Yoshimura N. The Contribution of Genetic Architecture to the 10-Year Incidence of Age-Related Macular Degeneration in the Fellow Eye. Invest Ophthalmol Vis Sci 2015;56(9):5353-61.Abstract

PURPOSE: To correlate a genetic risk score based on age-related macular degeneration (AMD) susceptibility genes with the risk of AMD in the second eye. METHODS: This is a retrospective, open cohort study consisting of 891 unilateral AMD patients, who were followed for at least 12 months and recruited from three institutes. DNAs were genotyped using Illumina OmniExpress, HumanOmni2.5-8, and/or HumanExome. Survival analyses and Cox proportional hazard models were used to examine the association between 11 AMD susceptibility genes and the duration until second-eye involvement in 499 samples from Kyoto University, which were replicated in two other cohorts. Genetic risk score (GRS) was also evaluated. RESULTS: The ARMS2 rs10490924 recessive model (hazard ratio [HR]meta = 2.04; Pmeta = 3.4 × 10-3) and CFH rs800292 additive model (HRmeta = 1.77; Pmeta = 0.013) revealed significant associations with second-eye involvement. The dominant model of TNFRSF10A rs13278062, VEGFA rs943080, and CFI rs4698775 showed consistent effects across three datasets (I2 = 0%; HRmeta = 1.46, 1.30, 1.51, respectively). The GRS using these five single nucleotide polymorphisms (SNPs) was also significantly associated (HRmeta [per score] = 2.42; P = 2.2 × 10-5; I2 = 0%). After 10 years from the first visit, the patients within the top 10% by GRS showed a 51% hazard rate, in contrast to 2.3% among patients within the lowest 10% by GRS. CONCLUSIONS: We demonstrated that the GRS using ARMS2, CFH, TNFRSF10A, VEGFA, and CFI was significantly associated with second-eye involvement. Genetic risk has high predictive ability for second-eye involvement of AMD.

Morrison MA, Magalhaes TR, Ramke J, Smith SE, Ennis S, Simpson CL, Portas L, Murgia F, Ahn J, Dardenne C, Mayne K, Robinson R, Morgan DJ, Brian G, Lee L, Woo SJ, Zacharaki F, Tsironi EE, Miller JW, Kim IK, Park KH, Bailey-Wilson JE, Farrer LA, Stambolian D, Deangelis MM. Ancestry of the Timorese: age-related macular degeneration associated genotype and allele sharing among human populations from throughout the world. Front Genet 2015;6:238.Abstract

We observed that the third leading cause of blindness in the world, age-related macular degeneration (AMD), occurs at a very low documented frequency in a population-based cohort from Timor-Leste. Thus, we determined a complete catalog of the ancestry of the Timorese by analysis of whole exome chip data and haplogroup analysis of SNP genotypes determined by sequencing the Hypervariable I and II regions of the mitochondrial genome and 17 genotyped YSTR markers obtained from 535 individuals. We genotyped 20 previously reported AMD-associated SNPs in the Timorese to examine their allele frequencies compared to and between previously documented AMD cohorts of varying ethnicities. For those without AMD (average age > 55 years), genotype and allele frequencies were similar for most SNPs with a few exceptions. The major risk allele of HTRA1 rs11200638 (10q26) was at a significantly higher frequency in the Timorese, as well as 3 of the 5 protective CFH (1q32) SNPs (rs800292, rs2284664, and rs12066959). Additionally, the most commonly associated AMD-risk SNP, CFH rs1061170 (Y402H), was also seen at a much lower frequency in the Korean and Timorese populations than in the assessed Caucasian populations (C ~7 vs. ~40%, respectively). The difference in allele frequencies between the Timorese population and the other genotyped populations, along with the haplogroup analysis, also highlight the genetic diversity of the Timorese. Specifically, the most common ancestry groupings were Oceanic (Melanesian and Papuan) and Eastern Asian (specifically Han Chinese). The low prevalence of AMD in the Timorese population (2 of 535 randomly selected participants) may be due to the enrichment of protective alleles in this population at the 1q32 locus.

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Narayanan D, Rodriguez J, Wallstrom G, Welch D, Chapin M, Arrigg P, Abelson M. An exploratory study to evaluate visual function endpoints in non-advanced age-related macular degeneration. BMC Ophthalmol 2020;20(1):424.Abstract
BACKGROUND: To prevent irreversible vision loss in age-related macular degeneration (AMD), it is critical to detect retinal dysfunction before permanent structural loss occurs. In the current study we evaluated a series of visual function tests to identify potential endpoints to detect visual dysfunction in non-advanced AMD. METHODS: A series of visual function tests were performed on 23 non-advanced AMD subjects (AREDS grade 1-4 on simplified scale) and 34 age-matched normals (AREDS grade 0). Tests included some commonly used endpoints such as ETDRS visual acuity (VA), low luminance (LL) 2.0ND ETDRS VA, MNREAD as well as newly developed tests such as the Ora-VCF™ test, Ora-tablet reading test, color sensitivity etc. Differences between the two groups were compared for each test. Test-retest repeatability and reproducibility was assessed on a subset of subjects and percent agreement was calculated. RESULTS: There was no difference in standard ETDRS VA between non-advanced AMD (0.06 ± 0.02 logMAR) and normal groups (0.04 ± 0.02 logMAR) (p = 0.57). LL 2.0 ETDRS VA and MNREAD showed no difference between the groups (p > 0.05). Ora-VCF™ test was significantly worse in the non-advanced AMD group compared to normals (0.67 ± 0.07 in AMD; 0.45 ± 0.04 in normals, p = 0.005). Non-advanced AMD subjects also had significantly worse reading performance using the Ora-tablet with LL 2.0ND (114.55 ± 11.22 wpm in AMD; 145.17 ± 9.55 wpm in normals p = 0.049). No significant difference between the groups was noted using other tests. Repeatability was 82% for Ora-VCF™ test and 92% for Ora-tablet LL 2.0ND reading. Reproducibility was 89% for both Ora-VCF™ test and Ora-tablet LL 2.0ND reading. CONCLUSION: While there was no significant difference between non-advanced AMD and normal groups using some current common endpoints such as ETDRS VA, LL 2.0 ETDRS VA or MNREAD, Ora-VCF™ test and Ora-tablet LL 2.0ND reading tests were able to identify significant visual dysfunction in non-advanced AMD subjects. These tests show promise as endpoints for AMD studies.
Narayanan D, Wallstrom G, Rodriguez J, Welch D, Chapin M, Arrigg P, Patil R, Abelson M. Early Ophthalmic Changes in Macula Does Not Correlate with Visual Function. Clin Ophthalmol 2020;14:2571-2576.Abstract
Purpose: Early detection and treatment of age-related macular degeneration require a clear understanding of the early progress of the disease. The purpose of this study was to investigate whether minimal macular ophthalmoscopic changes corresponded to changes in visual function. Methods: Color macular photos from a group of older subjects who were classified as grade 0 on AREDS simplified grading were further evaluated by a retinal specialist using 5x magnification for possible minimal macular anomalies. Group 0-A ( = 15) were defined as subjects with no visible macular anomalies while Group 0-B ( = 19) comprised subjects for whom minimal macular mottling, pigment changes or very small drusen (< 63 µm) were observed in the study eye. All subjects had best VA of 20/25 or better and had no evidence of other retinal diseases in the study eye. All subjects underwent a series of visual function tests such as standard ETDRS VA, low luminance ETDRS VA, Pelli-Robson contrast sensitivity, variable contrast flicker (VCF) sensitivity, and reading speed (words per minute, wpm) using both MNRead and low luminance reading on a tablet. Results: There was no significant difference between the mean age between the two groups (74.8 ± 5.2 years for 0-A vs 74.5 ± 4.4 for 0-B, = 0.82). None of the visual function tests identified any significant difference between the two groups. Mean ETDRS VA was 0.0 ± 0.11 for 0-A subjects and 0.08 ± 0.12 for 0-B ( = 0.063). Mean Pelli-Robson log contrast sensitivity was 1.75 ± 0.29 for 0-A and 1.78 ± 0.17 for the 0-B group ( = 0.73). VCF threshold was 0.47 ± 0.25 for 0-A and 0.43 ± 0.22 for 0-B ( = 0.64). Reading speed using MNRead was 214 ± 47.4 wpm for 0-A and 210 ± 64.7 for 0-B ( = 0.85). Low luminance tablet reading speed was 137 ± 71.8 wpm for 0-A and 151 ± 39.4 (0-B) ( = 0.49). Conclusion: A panel of psychophysical tests did not demonstrate significant differences between subjects with and without minimal macular changes.
Nigalye AK, Hess K, Pundlik SJ, Jeffrey BG, Cukras CA, Husain D. Dark Adaptation and Its Role in Age-Related Macular Degeneration. J Clin Med 2022;11(5)Abstract
Dark adaptation (DA) refers to the slow recovery of visual sensitivity in darkness following exposure to intense or prolonged illumination, which bleaches a significant amount of the rhodopsin. This natural process also offers an opportunity to understand cellular function in the outer retina and evaluate for presence of disease. How our eyes adapt to darkness can be a key indicator of retinal health, which can be altered in the presence of certain diseases, such as age-related macular degeneration (AMD). A specific focus on clinical aspects of DA measurement and its significance to furthering our understanding of AMD has revealed essential findings underlying the pathobiology of the disease. The process of dark adaptation involves phototransduction taking place mainly between the photoreceptor outer segments and the retinal pigment epithelial (RPE) layer. DA occurs over a large range of luminance and is modulated by both cone and rod photoreceptors. In the photopic ranges, rods are saturated and cone cells adapt to the high luminance levels. However, under scotopic ranges, cones are unable to respond to the dim luminance and rods modulate the responses to lower levels of light as they can respond to even a single photon. Since the cone visual cycle is also based on the Muller cells, measuring the impairment in rod-based dark adaptation is thought to be particularly relevant to diseases such as AMD, which involves both photoreceptors and RPE. Dark adaptation parameters are metrics derived from curve-fitting dark adaptation sensitivities over time and can represent specific cellular function. Parameters such as the cone-rod break (CRB) and rod intercept time (RIT) are particularly sensitive to changes in the outer retina. There is some structural and functional continuum between normal aging and the AMD pathology. Many studies have shown an increase of the rod intercept time (RIT), i.e., delays in rod-mediated DA in AMD patients with increasing disease severity determined by increased drusen grade, pigment changes and the presence of subretinal drusenoid deposits (SDD) and association with certain morphological features in the peripheral retina. Specifications of spatial testing location, repeatability of the testing, ease and availability of the testing device in clinical settings, and test duration in elderly population are also important. We provide a detailed overview in light of all these factors.
Nunes S, Alves D, Barreto P, Raimundo M, da Luz Cachulo M, Farinha C, Laíns I, Rodrigues J, Almeida C, Ribeiro L, Figueira J, Santos L, Silva R. Adherence to a mediterranean diet and its association with age-related macular degeneration. The Coimbra Eye Study-Report 4. Nutrition 2018;51-52:6-12.Abstract
OBJECTIVES: This study aimed to characterize the association of lifestyle and nutritional risk profiles with age-related macular degeneration (AMD) in two subpopulations with differing AMD prevalence. METHODS: This case-control study (n = 1992) included 768 patients with AMD and 1224 age- and sex-matched participants without AMD with a single visit at a primary health care unit. Enrolled participants completed a validated lifestyle and food frequency questionnaire. A score to measure adherence to the Mediterranean diet (mediSCORE; Range, 0-9) was constructed from individual food intakes, which were further analyzed by conversion to nutrient consumption. RESULTS: Higher adherence to the Mediterranean diet (mediSCORE ≥6) was significantly associated with no AMD (odds ratio [OR] = 0.73; P = 0.009). The subpopulation with lower AMD prevalence presented significantly higher adherence to the Mediterranean diet in relation to all individual food groups that comprised the mediSCORE (P < 0.014) with the exception of cereals. Food group analysis showed significant associations between the increased consumption of vegetables (OR = 0.63; P < 0.001) and fruit and nuts (OR = 0.78; P = 0.010) with no AMD. Nutrient analysis revealed that an increased ingestion of water, fibers, total fat, monounsaturated and polyunsaturated fatty acids, linoleic acid, vitamins A and C, carotene, alpha-tocopherol, folate, magnesium, iron, and zinc were significantly associated with no AMD (P < 0.0013). Finally, regular physical activity was associated with no AMD (P = 0.003). CONCLUSIONS: High adherence to a Mediterranean diet and regular physical activity seem to be protective factors for AMD in a Portuguese population. The effect of the diet is likely driven by the increased consumption of vegetables, fruits, and nuts.
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Orozco LD, Owen LA, Hofmann J, Stockwell AD, Tao J, Haller S, Mukundan VT, Clarke C, Lund J, Sridhar A, Mayba O, Barr JL, Zavala RA, Graves EC, Zhang C, Husami N, Finley R, Au E, Lillvis JH, Farkas MH, Shakoor A, Sherva R, Kim IK, Kaminker JS, Townsend MJ, Farrer LA, Yaspan BL, Chen H-H, Deangelis MM. A systems biology approach uncovers novel disease mechanisms in age-related macular degeneration. Cell Genom 2023;3(6):100302.Abstract
Age-related macular degeneration (AMD) is a leading cause of blindness, affecting 200 million people worldwide. To identify genes that could be targeted for treatment, we created a molecular atlas at different stages of AMD. Our resource is comprised of RNA sequencing (RNA-seq) and DNA methylation microarrays from bulk macular retinal pigment epithelium (RPE)/choroid of clinically phenotyped normal and AMD donor eyes (n = 85), single-nucleus RNA-seq (164,399 cells), and single-nucleus assay for transposase-accessible chromatin (ATAC)-seq (125,822 cells) from the retina, RPE, and choroid of 6 AMD and 7 control donors. We identified 23 genome-wide significant loci differentially methylated in AMD, over 1,000 differentially expressed genes across different disease stages, and an AMD Müller state distinct from normal or gliosis. Chromatin accessibility peaks in genome-wide association study (GWAS) loci revealed putative causal genes for AMD, including HTRA1 and C6orf223. Our systems biology approach uncovered molecular mechanisms underlying AMD, including regulators of WNT signaling, FRZB and TLE2, as mechanistic players in disease.
Owen LA, Shakoor A, Morgan DJ, Hejazi AA, McEntire WM, Brown JJ, Farrer LA, Kim I, Vitale A, Deangelis MM. The Utah Protocol for Postmortem Eye Phenotyping and Molecular Biochemical Analysis. Invest Ophthalmol Vis Sci 2019;60(4):1204-1212.Abstract
Purpose: Current understanding of local disease pathophysiology in AMD is limited. Analysis of the human disease-affected tissue is most informative, as gene expression, expressed quantitative trait loci, microenvironmental, and epigenetic changes can be tissue, cell type, and location specific. Development of a novel translational treatment and prevention strategies particularly for earlier forms of AMD are needed, although access to human ocular tissue analysis is challenging. We present a standardized protocol to study rapidly processed postmortem donor eyes for molecular biochemical and genomic studies. Methods: We partnered with the Utah Lions Eye Bank to obtain donor human eyes, blood, and vitreous, within 6 hours postmortem. Phenotypic analysis was performed using spectral-domain optical coherence tomography (SD-OCT) and color fundus photography. Macular and extramacular tissues were immediately isolated, and the neural retina and retinal pigment epithelium/choroid from each specimen were separated and preserved. Ocular disease phenotype was analyzed using clinically relevant grading criteria by a group of four ophthalmologists incorporating data from SD-OCT retinal images, fundus photographs, and medical records. Results: The use of multimodal imaging leads to greater resolution of retinal pathology, allowing greater phenotypic rigor for both interobserver phenotype and known clinical diagnoses. Further, our analysis resulted in excellent quality RNA, which demonstrated appropriate tissue segregation. Conclusions: The Utah protocol is a standardized methodology for analysis of disease mechanisms in AMD. It uniquely allows for simultaneous rigorous phenotypic, molecular biochemical, and genomic analysis of both systemic and local tissues. This better enables the development of disease biomarkers and therapeutic interventions.
Owen LA, Morrison MA, Ahn J, Woo SJ, Sato H, Robinson R, Morgan DJ, Zacharaki F, Simeonova M, Uehara H, Chakravarthy U, Hogg RE, Ambati BK, Kotoula M, Baehr W, Haider NB, Silvestri G, Miller JW, Tsironi EE, Farrer LA, Kim IK, Park KH, Deangelis MM. FLT1 genetic variation predisposes to neovascular AMD in ethnically diverse populations and alters systemic FLT1 expression. Invest Ophthalmol Vis Sci 2014;55(6):3543-54.Abstract
PURPOSE: Current understanding of the genetic risk factors for age-related macular degeneration (AMD) is not sufficiently predictive of the clinical course. The VEGF pathway is a key therapeutic target for treatment of neovascular AMD; however, risk attributable to genetic variation within pathway genes is unclear. We sought to identify single nucleotide polymorphisms (SNPs) associated with AMD within the VEGF pathway. METHODS: Using a tagSNP, direct sequencing and meta-analysis approach within four ethnically diverse cohorts, we identified genetic risk present in FLT1, though not within other VEGF pathway genes KDR, VEGFA, or VASH1. We used ChIP and ELISA in functional analysis. RESULTS: The FLT1 SNPs rs9943922, rs9508034, rs2281827, rs7324510, and rs9513115 were significantly associated with increased risk of neovascular AMD. Each association was more significant after meta-analysis than in any one of the four cohorts. All associations were novel, within noncoding regions of FLT1 that do not tag for coding variants in linkage disequilibrium. Analysis of soluble FLT1 demonstrated higher expression in unaffected individuals homozygous for the FLT1 risk alleles rs9943922 (P = 0.0086) and rs7324510 (P = 0.0057). In silico analysis suggests that these variants change predicted splice sites and RNA secondary structure, and have been identified in other neovascular pathologies. These data were supported further by murine chromatin immunoprecipitation demonstrating that FLT1 is a target of Nr2e3, a nuclear receptor gene implicated in regulating an AMD pathway. CONCLUSIONS: Although exact variant functions are not known, these data demonstrate relevancy across ethnically diverse genetic backgrounds within our study and, therefore, hold potential for global efficacy.
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Panigrahy D, Adini I, Mamluk R, Levonyak N, Bruns CJ, D'Amore PA, Klagsbrun M, Bielenberg DR. Regulation of soluble neuropilin 1, an endogenous angiogenesis inhibitor, in liver development and regeneration. Pathology 2014;46(5):416-23.Abstract

Neuropilin-1 (NRP1) is a receptor for vascular endothelial growth factor (VEGF). A soluble isoform of Nrp1 (sNrp1) has not been described in the mouse. Our goal was to examine the expression of mouse sNrp1 during liver development and regeneration.sNrp1 was cloned from mouse liver. The expression of sNrp1 and VEGF was examined in mouse liver during post-natal development and regeneration using northern blot, western blot, in situ hybridisation, and immunohistochemical analyses. HGF/NRP1 binding was examined in vitro.A novel 588-amino acid sNrp1 isoform was found to contain the ligand binding regions of Nrp1. The adult liver expressed more sNrp1 than full-length Nrp1. In vivo, hepatocytes constitutively expressed VEGF and sNrp1 in the quiescent state. sNrp1 was highly up-regulated at P20, a time point coinciding with a plateau in liver and body weights. Following hepatectomy, endogenous levels of sNrp1 decreased during the rapid growth phase, and VEGF levels were highest just prior to and during the angiogenic phase. sNrp1 levels again rose 5-10 days post-hepatectomy, presumably to control regeneration. HGF protein bound NRP1 and binding was competed with sNRP1.We cloned a novel mouse sNrp1 isoform from liver and provide evidence that this endogenous angiogenesis inhibitor may regulate VEGF or HGF bioavailability during normal physiological growth and development as well as during liver regeneration.

Papadopoulos Z. Aflibercept: A review of its effect on the treatment of exudative age-related macular degeneration. Eur J Ophthalmol 2019;29(4):368-378.Abstract
Considerable improvement has been achieved in the way in which exudative age-related macular degeneration is conventionally treated and in the associated visual outcomes and prognosis, thanks to the agents with effects against vascular endothelial growth factor (anti-VEGF). By comparison to earlier treatment approaches that involved the use of lasers, the anti-VEGF agents have made it possible to accomplish more positive visual and anatomical outcomes in cases of exudative age-related macular degeneration. Indeed, owing to their positive effects, anti-VEGF agents have quickly come to be considered the gold standard for the treatment of wet age-related macular degeneration. Aflibercept, the most recently approved intravitreally administered anti-VEGF, seems to mark another milestone in the treatment of wet age-related macular degeneration. This anti-VEGF agent presents a series of singular pharmacodynamic and pharmacokinetic attributes that provide it a number of biological benefits in relation to the treatment of choroidal neovascularization compared to other agents. These attributes include high level of affinity for the VEGF-A factor, an intravitreal half-life of great length, as well as the ability to serve as an antagonist for other growth factors besides VEGF. The impact of Aflibercept on the manner in which exudative age-related macular degeneration is managed was demonstrated by thoroughly reviewing the related literature. The present review article highlights the pharmacology, pharmacokinetics, safety and effectiveness of this anti-VEGF agent as well as the landmark clinical studies that have been carried out to establish this drug as a gold standard in the therapy of neovascular age-related macular degeneration. In addition, studies regarding the outcomes and effectiveness of the various dosage regimens, either as monotherapy or in combination with other agents, are also reviewed.
Papadopoulos Z. Recent Developments in the Treatment of Wet Age-related Macular Degeneration. Curr Med Sci 2020;40(5):851-857.Abstract
Age-related macular degeneration (AMD) is the most common cause of irreversible blindness and visual impairment in individuals over the age of 50 years in western societies. More than 25 million people currently suffer from this illness in the world, with an additional 500 000 every year, approximately. It is a multifactorial ocular disease that affects the maculae due to a late-onset progressive neurodegeneration and dysfunction of photoreceptors and retinal pigment epithelium (RPE). There are many subtypes of AMD but basically two broad forms: the nonneovascular (dry, nonexudative) and neovascular (wet, exudative). Exudative AMD is the less common form (about 15%) but tends to progress more rapidly. At the moment, wet AMD is treated primarily on the basis of anti-vascular endothelial growth factor (VEGF) agents, which have led to massive improvement in the prognosis of the disease since they were first introduced. This article focuses on the latest treatment approaches to neovascular AMD. An extensive literature review was performed in order to illustrate the effectiveness of current and future anti-VEGF agents as well as the landmark clinical studies that have been carried out to establish these drugs as a gold standard in the therapy of wet AMD.
Papadopoulos Z. Neovascular age-related macular degeneration and its association with Alzheimer's disease. Curr Aging Sci 2020;Abstract
In developed countries, people of advanced age go permanently blind most often due to age-related macular degeneration, while at global level, this disease is the third major cause of blindness, after cataract and glaucoma, according to the World Health Organisation. The number of individuals believed to suffer from the disease throughout the world has been approximated at 50 million. Age-related macular degeneration is classified as non-neovascular (dry, non-exudative) and neovascular (wet, exudative). The exudative form is less common than the non-exudative as it accounts for approximately 10 percent of the cases of the disease. However, it can be much more aggressive and results in a rapid and severe loss of central vision. Similarly with age-related macular degeneration, Alzheimer's disease is a late-onset, neurodegenerative disease affecting millions of people worldwide. Both of them are associated with age and share several features, including the presence of extracellular abnormal deposits associated with neuronal degeneration, drusen, and plaques, respectively. The present review article highlights the pathogenesis, the clinical features and the imaging modalities used for the diagnosis of neovascular age-related macular degeneration. A thorough overview of the effectiveness of anti-VEGF agents as well as of other treatment modalities that have either lost favour or are rarely used is provided in detail. Additionally, the common histologic, immunologic, and pathogenetic features of Alzheimer's disease and age-related macular degeneration are discussed in depth.

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