Mechanisms of age-related macular degeneration and therapeutic opportunities

A narrative review on dietary components and patterns and age-related macular degeneration

Age-related macular degeneration (AMD) is one of the most prevalent eye diseases among the ageing population worldwide. It is a leading cause of blindness in individuals over 55, particularly in industrialised Western countries. The prevalence of AMD increases with age, and genetic factors and environmental influences are believed to contribute to its development. Among the environmental factors, diet plays a significant role in AMD. This review explores the association between dietary components, dietary patterns and AMD. Various nutrients, non-nutrient substances and dietary models that have the potential to counteract oxidative stress and inflammation, which are underlying mechanisms of AMD, are discussed. Consuming fruits, vegetables, fish and seafood, whole grains, olive oil, nuts and low-glycaemic-index foods has been highlighted as beneficial for reducing the risk of AMD. Adhering to the Mediterranean diet, which encompasses these elements, can be recommended as a dietary pattern for AMD. Furthermore, the modulation of the gut microbiota through dietary interventions and probiotics has shown promise in managing AMD.

PRL3-zumab as an anti-angiogenic therapy in neovascular eye diseases

Neovascular eye diseases represent a major cause of irreversible blindness. Here, we report the specific upregulation of endogenous PRL3 protein in diseased choroid-RPE in choroidal neovascularization (CNV) mouse model (male), and diseased retina in oxygen-induced retinopathy (OIR) mouse model (mixed gender), indicating PRL3's role in neovascularization. Intravenous (IV) delivery of anti-PRL3 antibody in CNV model demonstrates superior efficacy in reducing vascular leakage compared to intravitreal (IVT) route due to larger dose permitted by IV. VEGF treatment upregulates endogenous PRL3 protein in human retinal microvascular endothelial cells (HRMECs). Retroviral PRL3 overexpression in HRMECs promotes endothelial proliferation, migration and permeability by facilitating the phosphorylation of ERK1/2, AKT, Paxillin and SRC. However, VEGF-induced proliferation is absent in PRL3-knockout HRMECs. PRL3-zumab, an anti-PRL3 humanized monoclonal antibody, has shown a strong safety profile in ongoing multi-national Phase II trials as an intravenous-administered cancer immunotherapeutic. PRL3's involvement in ocular pathological angiogenesis suggests the potential of repurposing PRL3-zumab to treat neovascular eye diseases.

Immune Checkpoint PD-L1 Modulates Retinal Microglial Activation to Alleviate Vascular Leakage in Choroidal Neovascularization via ERK

Neovascular age-related macular degeneration (NVAMD) is a common retinal disease causing vision loss in the elderly. Neuroinflammation significantly contributes to NVAMD's etiology. This study explores the role of Programmed cell death ligand 1 (PD-L1), an immune checkpoint (ICP) in microglia, known for limiting neuroinflammation in neurodegenerative diseases, and its potential function in NVAMD. This work finds increased PD-L1 expression in retinal microglia following laser injury. PD-L1 knockout (KO) or inhibitory PD-L1 antibody treatment worsens vascular leakage and neoangiogenesis in a laser-induced NVAMD mouse model, effects reversible by microglia depletion with PLX5622. This study underscores that choroidal neovascularization (CNV) may be regulated by multiple mechanisms, with PD-L1 modulation representing one of these pathways. Blocking PD-L1 elevated proinflammatory factors and p-ERK levels, indicating microglial overactivation in NVAMD. Conversely, enhancing PD-L1 signaling reduced neuroinflammation and neovascularization via ERK. These findings highlight PD-L1's role in neoangiogenesis and neuroinflammation in NVAMD, suggesting its potential as a target for immunomodulatory treatment in NVAMD.

Cathepsins and age-related macular degeneration: A Mendelian randomization study unveiling causal relationships

Age-related macular degeneration (AMD) is a leading cause of vision impairment and blindness in older adults, profoundly affecting millions of individuals worldwide. Cathepsins are a crucial class of proteolytic enzymes that participates in multiple biological process. However, the role of cathepsins in AMD still remains unclear. This study aims to probe into the causal relationship between cathepsins and AMD using a 2-sample Mendelian randomization (MR). Instrumental variables associated with exposure (cathepsins) and the outcome (AMD) were sourced from published genome-wide association studies. To estimate the causal effects, methodologies such as inverse variance weighted, MR-Egger, and weighted median estimation (WM) were employed. Reverse MR and multivariate MR analyses were also performed. The elevated levels of cathepsin B significantly increased the risk of dry AMD, with an odds ratio (OR) of 1.068 (95% CI = 1.007-1.133) and a P-value of .029). Sensitivity analyses confirmed the robustness of these findings, with no evidence of heterogeneity or pleiotropy. Reverse MR analyses indicated that total AMD might elevate levels of cathepsin E (OR = 1.04, P = .029). Multivariate MR analysis showed significant associations between specific cathepsins and AMD subtypes, including cathepsin G and cathepsin O with significantly increasing risk. The study revealed a potential causal effect of cathepsin B on AMD, especially dry AMD. These findings provide potential therapeutic targets for AMD, and further research is needed to understand the underlying mechanisms.

Animal models for the evaluation of retinal stem cell therapies

Retinal degeneration (RD) diseases leading to severe vision loss can affect photoreceptors (PRs) that are responsible for phototransduction, or retinal pigmented epithelium (RPE) providing support for PRs. Human pluripotent stem cell (hPSC)-based therapies are a potential approach for restoration of retinal structure in patients with currently incurable RD diseases. Currently, there are two targeted hPSC therapeutics: PR rescue and PR replacement. PR rescue involves the transplantation of RPE or other neural progenitors into the subretinal space to slow down or prevent further RD. RPE transplantation plays a critical role in preserving photoreceptors by providing trophic support and maintaining retinal integrity, particularly in diseases like age-related macular degeneration (AMD). Advances in RPE transplantation methods, such as polarized monolayer cultures and scaffold-based approaches, have shown promise in enhancing graft survival and integration. However, limitations include inconsistent integration, variable neurotrophic factor secretion, and immune rejection risks in non-autologous transplants. In PR replacement, stem cell-derived photoreceptor-like cells or photoreceptor progenitors (PRP) obtained are transplanted into the eye. While PRPs are commonly obtained from retinal organoids (ROs), alternative sources, such as early differentiation stages or direct differentiation protocols, are also utilized to enhance the efficiency and scalability of PRP generation. Challenges include achieving proper integration, forming outer segments, rosette formation, and avoiding immune rejection or tumorigenicity. Various animal models that simulate human RD diseases are being used for establishing surgical feasibility, graft survival and visual functional recovery but fail to replicate clinical immune challenges. Rodent models lack macula-like structures and have limited reliability in detecting subtle functional changes, while larger animal models pose ethical, logistical, and financial challenges. Immunocompromised models have been developed for minimizing xenograft issues. Visual functional testing for efficacy includes optokinetic testing (OKN), electroretinography (ERG), and electrophysiological recordings from the retina and brain. These tests often fail to capture the complexity of human visual recovery, highlighting the need for advanced models and improved functional testing techniques. This review aims to aggregate current knowledge about approaches to stem cell transplantation, requirements of animal models chosen for validating vision benefits of transplantation studies, advantages of using specific disease models and their limitations. While promising strides have been made, addressing these limitations remains essential for translating stem cell-based therapies into clinical success.

Therapeutic potential of adult stem cells-derived mitochondria transfer combined with curcumin administration into ARPE-19 cells in age-related macular degeneration model

OBJECTIVE

Mitochondria transfer from human Wharton's Jelly-derived mesenchymal stem cells (hWJ-MSCs-mt) and human endometrium-derived mesenchymal stem cells (hE-MSCs-mt), along with curcumin, were explored as potential treatments for age-related macular degeneration (AMD) caused by mitochondrial inefficiency, using a retinal model to assess impacts of curcumin and hWJ-MSCs-mt or hE-MSCs-mt on AMD.

METHODS

ARPE-19 cells established an in vitro AMD model. Cells were exposed to 0-50 μM curcumin for 24 hours to determine optimal concentration by assessing their viability. Immunofluorescence examined SOD1, TNF-α, and TGF-β levels at optimal hydrogen peroxide (H2O2) concentration. β-galactosidase staining and DCFH analysis evaluated H2O2-induced cellular senescence. Immunofluorescence assessed REP65, CRALBP1 (RLBP1), Pink1, and Parkin expression, whereas qRT-PCR analyzed Nrf2, Ire1a, ARMS2, HTRA1, RPE65, RLBP1, NOX4, and TOMM20 expression following co-treatment with curcumin and hWJ-MSCs-mt or hE-MSCs-mt.

RESULTS

Curcumin improved ARPE-19 cell survival under H2O2-induced oxidative stress by regulating SOD1, TNF-α, TGF-β, DCFH, and MDA levels. hWJ-MSCs-mt transfer increased RLBP1 and Parkin expression, whereas curcumin reduced Parkin expression. hE-MSCs-mt transfer upregulated Parkin, RPE65, Pink1, and RLBP1 expressions, with curcumin enhancing RPE65 expression. hWJ-MSCs-mt and curcumin combined more effectively downregulated expressions of stress-related genes (Nrf2, Ire1α, NOX4) and improved expression of mitochondrial function gene (TOMM20). hE-MSCs-mt transfer with curcumin synergistically enhanced expression of retinal health markers (RPE65, RLBP1) and downregulated expression of damage-associated genes (HTRA1, ARMS2) in AMD models.

CONCLUSION

Curcumin combined with hWJ-MSCs-mt or hE-MSCs-mt is a potential AMD therapy owing to its anti-inflammatory properties; however, further in vivo and human studies are needed to confirm its efficacy and safety.

Diagnostic testing in the genetically complex age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of visual impairment with the risk of developing the disease influenced by a combination of genetic and environmental factors. With the recent expansion of treatment options, enhancing diagnostic accuracy and improving access to treatment are increasingly becoming the focus of interest. By using data from genome-wide association studies (GWAS) to generate polygenic risk scores (PRS), an assessment of an individual's genetic risk for AMD is feasible. While the predictive accuracy of the AMD-PRS is most robust for individuals at very high genetic risk, genetic diagnostic testing is warranted due to the large number of affected individuals resulting from the high prevalence of AMD. Early genetic confirmation of AMD-related pathology can facilitate timely treatment initiation, potentially improving patient outcomes.

Variation of Structures and Blood Vessels of Visual Nervous System With Age

Aging is a process of progressive functional decline associated with increasing age. The process and mechanism of aging have long been widely concerned, but long-term in vivo evaluations of the visual nervous system have not been previously reported. In this study, naturally aging mouse models were used for long-term serial evaluation, and the changes in structure and blood flow of the retina and cerebral cortex were systematically analyzed. Optical Coherence Tomography (OCT) and Optical Coherence Tomography Angiography (OCTA) were performed on mice at 3, 6, 9, and 12 months of age, respectively. Structural and vascular changes with age were quantitatively evaluated. Results show that the reduction of structural thickness and vascular density of the retinal and cerebral cortex is observed. A significant correlation is also found between structural and vascular changes in the retina and cerebral cortex, indicating a consistent impact of aging on the visual nervous system.

Treat-And-Extend Versus Pro Re Nata Regimen of Intravitreal Conbercept Injection for Neovascular Age-Related Macular Degeneration: Results from COCOA, a Prospective, Open-Label, Multicenter, Randomized Phase IV Clinical Trial

PURPOSE

To evaluate and contrast the effectiveness and safety of two conbercept treatment protocols-a three-dose treat-and-extend (3+T&E) regimen and a three-dose pro re nata (3+PRN) regimen-in Chinese patients diagnosed with neovascular age-related macular degeneration (nAMD).

METHODS

Eligible patients, who had not undergone anti-VEGF intraocular injections within 3 months prior to enrollment, were randomly assigned to either the 3+T&E or 3+PRN regimen. The 3+T&E group received at least three monthly injections, with subsequent visit intervals extended based on disease activity assessment. The primary endpoint was the mean change in best-corrected visual acuity (BCVA) from baseline to week 48, using a predefined noninferiority threshold.

RESULTS

Among 501 participants (249 in 3+T&E, 252 in 3+PRN), approximately half had prior anti-VEGF treatment. At 48 weeks, both regimens showed significant BCVA improvements (+9.9 for 3+PRN, +8.6 for 3+T&E; p = .208), with comparable rates of ≥15-letter gains (32.12% for 3+PRN, 30.77% for 3+T&E; p = .827). The 3+PRN group received fewer injections (mean 6.4 vs. 6.9 in 3+T&E; p = .028) but had shorter intervals between injections (6.93 weeks vs. 7.46 weeks in 3+T&E; p = .010). Drug-related adverse events occurred in 5% of patients, with ocular events evenly distributed and minimal cardiovascular events reported.

CONCLUSION

Both 3+T&E and 3+PRN conbercept regimens effectively improved visual and anatomical outcomes in Chinese nAMD patients. The 3+T&E regimen was noninferior to 3+PRN in improving BCVA from baseline to week 48. The 3+T&E regimen enabled longer injection intervals while 3+PRN regimen with less injections is more cost-effective while maintaining a comparable safety profile. Treatment plan tailored to an individual patient's situation appears necessary.

Rac1 overexpression promotes Treg-derived cytokines to mediate choroidal neovascularization in wet age-related macular degeneration

Age-related macular degeneration (AMD), particularly the wet form characterized by choroidal neovascularization, is a leading cause of vision loss. Dysregulation of regulatory T cells (Tregs), key modulators of inflammatory responses, may contribute to wet AMD pathogenesis. This study explored the involvement of Tregs and the Rac1 signaling pathway in modulating Treg-derived cytokine expression and their role in choroidal neovascularization during wet AMD progression. Peripheral blood samples from healthy controls, dry AMD patients, and wet AMD patients were collected. An in vitro transmembrane co-culture system of Tregs and human choroidal endothelial cells (HCECs) was employed to investigate the impact of Tregs (with or without Rac1 silencing) on the angiogenic phenotype of HCECs. A mouse model of AMD was established to evaluate the effects of a Rac1 inhibitor and IL-10/TGF-β neutralization on Tregs and choroidal neovascularization. An increased Treg percentage in the CD4+ T lymphocyte population was found in the peripheral blood samples of wet AMD patients. Tregs from wet AMD patients showed an increased expression of Rac1 and an elevated production of IL-10 and TGF-β1. Rac1 silencing suppressed Treg stability and differentiation, and impaired the pro-angiogenic effect of Tregs on HCECs. In the animal model of AMD, the administration of a Rac1 inhibitor or neutralizing antibodies against IL-10/TGF-β1 reduced Treg abundance and attenuated choroidal neovascularization. Rac1 upregulation in Tregs promoted IL-10 and TGF-β1 production to mediate choroidal neovascularization in wet AMD. Targeting Rac1 and Treg-derived IL-10/TGF-β1 production in Tregs may serve as a strategy to ameliorate AMD progression.

Efficacy and safety of brolucizumab every 6 weeks induction therapy for neovascular age-related macular degeneration

This retrospective study aims to evaluate the short-term efficacy and safety of brolucizumab every 6 weeks induction therapy for neovascular age-related macular degeneration (nAMD) cases. This study included 140 eyes from 140 patients (101 males and 39 females, with a mean age of 77.7 ± 8.7 years) with nAMD who received brolucizumab injections every 6 weeks as part of induction therapy across four participating centers between June 2020 and March 2024. Follow-up lasted for at least 20-24 weeks. Data collected included age, sex, history of nAMD treatment, best-corrected visual acuity (BCVA), central retinal thickness (CRT), presence or absence of exudation, and occurrence of intraocular inflammation (IOI). Sixty-one eyes had prior nAMD treatment. Mean BCVA (logMAR) was 0.40 ± 0.43 before brolucizumab therapy, improving to 0.38 ± 0.42, 0.33 ± 0.41, and 0.34 ± 0.44 after the first, second, and third injections, respectively. Significant improvements in BCVA were observed from the second injection onward (p < 0.05). CRT decreased significantly from baseline of 341.6 ± 151.0 to 219.1 ± 119.8, 204.0 ± 112.9, and 200.8 ± 96.0 after the first, second, and third injections, respectively (p < 1.0 × 10-20). Exudative findings, present in all cases before treatment, resolved in 64.3%, 82.1%, and 79.3% of cases after the first, second, and third injections, respectively. IOI was observed in five, three, and four eyes after the first, second, and third injections, respectively, accounting for 8.6% of all cases. No cases had retinal vasculitis or occlusion. In conclusion, brolucizumab administered every 6 weeks as induction therapy for nAMD showed favorable efficacy and safety outcomes during a 6-month follow-up.

Exploring ocular disorders in Parkinson's disease: A comprehensive review and future perspectives

Parkinson's disease (PD) is a multifaceted neurodegenerative disorder characterized by predominantly motor symptoms. However, recent research has broadened our understanding of PD by revealing its impact on non-motor functions, including ocular manifestations. This review explored the intricate relationship between PD and ocular health, shedding light on the mechanisms underlying common ocular diseases such as dry eye disease, cataract, glaucoma, age-related macular degeneration, and diabetic retinopathy. It also underscores the importance of recognizing ocular manifestations as potential early markers of PD, as well as their impact on patients' daily activities, necessitating prompt identification and intervention to prevent complications and enhance the overall quality of life. Furthermore, future research should prioritize unraveling the potential association between PD and other prevalent ocular diseases, such as myopia, to formulate effective treatment strategies.

Signaling Pathways in Retinal Pigment Epithelium (RPE) Cells in Response to Stress Conditions of Age-Related Macular Degeneration (AMD)

Age-related macular degeneration (AMD), affecting circa 200 million people worldwide, is a debilitating disease leading to visual loss in the elderly population. The main risk for AMD is advanced age. Genetic predisposition as well as modern lifestyle habits, such as smoking or unhealthy diets, increase this risk. On the molecular level, these risks convert into complex systemic changes at the interface of the choriocapillaris, Bruch's membrane, RPE, and neuroretina, affecting the functional integrity and survival of RPE and photoreceptors cells. To date, therapeutic options for AMD patients are limited. Pathway identification and a detailed understanding of the molecular mechanisms driving AMD are prerequisites to defining potential novel druggable targets. This review aims to give a short overview of the known cell signaling pathways focusing on RPE cells in response to stress conditions occurring in AMD.

Eye on the horizon: The metabolic landscape of the RPE in aging and disease

To meet the prodigious bioenergetic demands of the photoreceptors, glucose and other nutrients must traverse the retinal pigment epithelium (RPE), a polarised monolayer of cells that lie at the interface between the outer retina and the choroid, the principal vascular layer of the eye. Recent investigations have revealed a metabolic ecosystem in the outer retina where the photoreceptors and RPE engage in a complex exchange of sugars, amino acids, and other metabolites. Perturbation of this delicate metabolic balance has been identified in the aging retina, as well as in age-related macular degeneration (AMD), the leading cause of blindness in the Western world. Also common in the aging and diseased retina are elevated levels of cytokines, oxidative stress, advanced glycation end-products, increased growth factor signalling, and biomechanical stress - all of which have been associated with metabolic dysregulation in non-retinal cell types and tissues. Herein, we outline the role of these factors in retinal homeostasis, aging, and disease. We discuss their effects on glucose, mitochondrial, lipid, and amino acid metabolism in tissues and cell types outside the retina, highlighting the signalling pathways through which they induce these changes. Lastly, we discuss promising avenues for future research investigating the roles of these pathological conditions on retinal metabolism, potentially offering novel therapeutic approaches to combat age-related retinal disease.

CYLD Maintains Retinal Homeostasis by Deubiquitinating ENKD1 and Promoting the Phagocytosis of Photoreceptor Outer Segments

Phagocytosis of shed photoreceptor outer segments by the retinal pigment epithelium (RPE) is essential for retinal homeostasis. Dysregulation of the phagocytotic process is associated with irreversible retinal degenerative diseases. However, the molecular mechanisms underlying the phagocytic activity of RPE cells remain elusive. In an effort to uncover proteins orchestrating retinal function, the cylindromatosis (CYLD) deubiquitinase is identified as a critical regulator of photoreceptor outer segment phagocytosis. CYLD-deficient mice exhibit abnormal retinal structure and function. Mechanistically, CYLD interacts with enkurin domain containing protein 1 (ENKD1) and deubiquitinates ENKD1 at lysine residues K141 and K242. Deubiquitinated ENKD1 interacts with Ezrin, a membrane-cytoskeleton linker, and stimulates the microvillar localization of Ezrin, which is essential for the phagocytic activity of RPE cells. These findings thus reveal a crucial role for the CYLD-ENKD1-Ezrin axis in regulating retinal homeostasis and may have important implications for the prevention and treatment of retinal degenerative diseases.

Targeting glutamine synthetase with AS1411-modified exosome-liposome hybrid nanoparticles for inhibition of choroidal neovascularization

Choroidal neovascularization (CNV) is a leading cause of visual impairment in wet age-related macular degeneration (wAMD). Recent investigations have validated the potential of reducing glutamine synthetase (GS) to inhibit neovascularization formation, offering prospects for treating various neovascularization-related diseases. In this study, we devised a CRISPR/Cas9 delivery system employing the nucleic acid aptamer AS1411 as a targeting moiety and exosome-liposome hybrid nanoparticles as carriers (CAELN). Exploiting the binding affinity between AS1411 and nucleolin on endothelial cell surfaces, the delivery system was engineered to specifically target the glutamine synthetase gene (GLUL), thereby attenuating GS levels and continuously suppressing CNV. CAELN exhibited spherical and uniform dispersion. In vitro cellular investigations demonstrated gene editing efficiencies of CAELN ranging from 42.05 to 55.02% and its capacity to inhibit neovascularization in HUVEC cells. Moreover, in vivo pharmacodynamic studies conducted in CNV rabbits revealed efficacy of CAELN in restoring the thickness of intra- and extranuclear tissues. The findings suggest that GS is a novel target for the inhibition of pathological CNV, while the development of AS1411-modified exosome-liposome hybrid nanoparticles represents a novel delivery method for the treatment of neovascular-related diseases.

The impact of NF-κB on inflammatory and angiogenic processes in age-related macular degeneration

Age-related macular degeneration (AMD) is a prominent cause of vision loss, characterized by two different types, dry (atrophic) and wet (neovascular). Dry AMD is distinguished by the progressive deterioration of retinal cells, which ultimately causes a decline in vision. In contrast, wet AMD is defined by the abnormal development of blood vessels underneath the retina, leading to a sudden and severe vision impairment. The course of AMD is primarily driven by chronic inflammation and pathological angiogenesis, in which the NF-κB signaling pathway plays a crucial role. The activation of NF-κB results in the generation of pro-inflammatory cytokines, chemokines, and angiogenic factors like VEGF, which contribute to inflammation and the formation of new blood vessels in AMD. This review analyzes the intricate relationship between NF-κB signaling, inflammation, and angiogenesis in AMD and assesses the possibility of using NF-κB as a target for therapy. The evaluation involves a comprehensive examination of preclinical and clinical evidence that substantiates the effectiveness of NF-κB inhibitors in treating AMD by diminishing inflammation and pathological angiogenesis.

Revolutionizing Eye Care: Exploring the Potential of Microneedle Drug Delivery

Microneedle technology revolutionizes ocular drug delivery by addressing challenges in treating ocular diseases. This review explores its potential impact, recent advancements, and clinical uses. This minimally invasive technique offers precise control of drug delivery to the eye, with various microneedle types showing the potential to penetrate barriers in the cornea and sclera, ensuring effective drug delivery. Recent advancements have improved safety and efficacy, offering sustained and controlled drug delivery for conditions like age-related macular degeneration and glaucoma. While promising, challenges such as regulatory barriers and long-term biocompatibility persist. Overcoming these through interdisciplinary research is crucial. Ultimately, microneedle drug delivery presents a revolutionary method with the potential to significantly enhance ocular disease treatment, marking a new era in eye care.

SLC16A8 is a causal contributor to age-related macular degeneration risk

Age-related macular degeneration (AMD), a complex neurodegenerative disease, is a leading cause of visual impairment worldwide with a strong genetic component. Genetic studies have identified several loci, but few causal genes with functional characterization. Here we highlight multiple lines of evidence which show a causal role in AMD for SLC16A8, which encodes MCT3, a retinal pigment epithelium (RPE) specific lactate transporter. First, in an unbiased, genome-wide analysis of rare coding variants we show multiple SLC16A8 rare variants are associated with AMD risk, corroborating previous borderline significant reports from AMD rare variant studies. Second, we report a novel SLC16A8 mutation in a three-generation family with early onset macular degeneration. Finally, mis-expression in multiple model organisms shows functional and anatomic retinal consequences. This study highlights the important role for SLC16A8 and lactate regulation towards outer retina/RPE health and highlights a potential new therapeutic opportunity for the treatment of AMD.

Artificial intelligence for diagnosing exudative age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is a retinal disorder characterized by central retinal (macular) damage. Approximately 10% to 20% of non-exudative AMD cases progress to the exudative form, which may result in rapid deterioration of central vision. Individuals with exudative AMD (eAMD) need prompt consultation with retinal specialists to minimize the risk and extent of vision loss. Traditional methods of diagnosing ophthalmic disease rely on clinical evaluation and multiple imaging techniques, which can be resource-consuming. Tests leveraging artificial intelligence (AI) hold the promise of automatically identifying and categorizing pathological features, enabling the timely diagnosis and treatment of eAMD.

OBJECTIVES

To determine the diagnostic accuracy of artificial intelligence (AI) as a triaging tool for exudative age-related macular degeneration (eAMD).

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, three clinical trials registries, and Data Archiving and Networked Services (DANS) for gray literature. We did not restrict searches by language or publication date. The date of the last search was April 2024.

SELECTION CRITERIA

Included studies compared the test performance of algorithms with that of human readers to detect eAMD on retinal images collected from people with AMD who were evaluated at eye clinics in community or academic medical centers, and who were not receiving treatment for eAMD when the images were taken. We included algorithms that were either internally or externally validated or both.

DATA COLLECTION AND ANALYSIS

Pairs of review authors independently extracted data and assessed study quality using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool with revised signaling questions. For studies that reported more than one set of performance results, we extracted only one set of diagnostic accuracy data per study based on the last development stage or the optimal algorithm as indicated by the study authors. For two-class algorithms, we collected data from the 2x2 table whenever feasible. For multi-class algorithms, we first consolidated data from all classes other than eAMD before constructing the corresponding 2x2 tables. Assuming a common positivity threshold applied by the included studies, we chose random-effects, bivariate logistic models to estimate summary sensitivity and specificity as the primary performance metrics.

MAIN RESULTS

We identified 36 eligible studies that reported 40 sets of algorithm performance data, encompassing over 16,000 participants and 62,000 images. We included 28 studies (78%) that reported 31 algorithms with performance data in the meta-analysis. The remaining nine studies (25%) reported eight algorithms that lacked usable performance data; we reported them in the qualitative synthesis. Study characteristics and risk of bias Most studies were conducted in Asia, followed by Europe, the USA, and collaborative efforts spanning multiple countries. Most studies identified study participants from the hospital setting, while others used retinal images from public repositories; a few studies did not specify image sources. Based on four of the 36 studies reporting demographic information, the age of the study participants ranged from 62 to 82 years. The included algorithms used various retinal image types as model input, such as optical coherence tomography (OCT) images (N = 15), fundus images (N = 6), and multi-modal imaging (N = 7). The predominant core method used was deep neural networks. All studies that reported externally validated algorithms were at high risk of bias mainly due to potential selection bias from either a two-gate design or the inappropriate exclusion of potentially eligible retinal images (or participants). Findings Only three of the 40 included algorithms were externally validated (7.5%, 3/40). The summary sensitivity and specificity were 0.94 (95% confidence interval (CI) 0.90 to 0.97) and 0.99 (95% CI 0.76 to 1.00), respectively, when compared to human graders (3 studies; 27,872 images; low-certainty evidence). The prevalence of images with eAMD ranged from 0.3% to 49%. Twenty-eight algorithms were reportedly either internally validated (20%, 8/40) or tested on a development set (50%, 20/40); the pooled sensitivity and specificity were 0.93 (95% CI 0.89 to 0.96) and 0.96 (95% CI 0.94 to 0.98), respectively, when compared to human graders (28 studies; 33,409 images; low-certainty evidence). We did not identify significant sources of heterogeneity among these 28 algorithms. Although algorithms using OCT images appeared more homogeneous and had the highest summary specificity (0.97, 95% CI 0.93 to 0.98), they were not superior to algorithms using fundus images alone (0.94, 95% CI 0.89 to 0.97) or multimodal imaging (0.96, 95% CI 0.88 to 0.99; P for meta-regression = 0.239). The median prevalence of images with eAMD was 30% (interquartile range [IQR] 22% to 39%). We did not include eight studies that described nine algorithms (one study reported two sets of algorithm results) to distinguish eAMD from normal images, images of other AMD, or other non-AMD retinal lesions in the meta-analysis. Five of these algorithms were generally based on smaller datasets (range 21 to 218 participants per study) yet with a higher prevalence of eAMD images (range 33% to 66%). Relative to human graders, the reported sensitivity in these studies ranged from 0.95 and 0.97, while the specificity ranged from 0.94 to 0.99. Similarly, using small datasets (range 46 to 106), an additional four algorithms for detecting eAMD from other retinal lesions showed high sensitivity (range 0.96 to 1.00) and specificity (range 0.77 to 1.00).

AUTHORS' CONCLUSIONS

Low- to very low-certainty evidence suggests that an algorithm-based test may correctly identify most individuals with eAMD without increasing unnecessary referrals (false positives) in either the primary or the specialty care settings. There were significant concerns for applying the review findings due to variations in the eAMD prevalence in the included studies. In addition, among the included algorithm-based tests, diagnostic accuracy estimates were at risk of bias due to study participants not reflecting real-world characteristics, inadequate model validation, and the likelihood of selective results reporting. Limited quality and quantity of externally validated algorithms highlighted the need for high-certainty evidence. This evidence will require a standardized definition for eAMD on different imaging modalities and external validation of the algorithm to assess generalizability.

Exploring the protective effects of Qiju Granule in a rat model of dry age-related macular degeneration

AIM

The aim of this study was to evaluate the potential protective effect of Qiju Granule in a rat model of age-related macular degeneration (AMD) and investigate the underlying mechanisms involved.

METHODS

Rats were injected intravenously with 40 mg/kg of sodium iodate (SI) to induce a dry AMD model. The rats in the treatment group received three different doses of Qiju Granule once a day via gavage, while the rats in the control group were given an equal volume of physiological saline. On day 14 and day 28 following the intervention, various methods were employed to evaluate retinal function and structure, including electroretinography (ERG), optical coherence tomography (OCT), and histological examination. The expression of glial fibrillary acidic protein (GFAP), basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF), and ciliary neurotrophic factor (CNTF) was assessed via immunofluorescence. Beyond immunofluorescence, the mRNA levels of bFGF, BDNF, and CNTF were quantitatively determined using real-time polymerase chain reaction (qRT-PCR).

RESULTS

Rats treated with Qiju Granule exhibited significant improvements in both retinal function and structure compared to the model group. The most noteworthy effects were observed at a high dose of Qiju Granule. Furthermore, the expression levels of bFGF, BDNF, and CNTF were significantly unregulated in the treated groups compared to the model group.

CONCLUSIONS

Qiju Granule demonstrated a protective effect on the retina in the SI-induced rat model of AMD. The protective mechanism may be attributed to the upregulation of retinal neurotrophic factors expression.

Baseline characteristics associated with the first year treatment interval of intravitreal faricimab in neovascular age-related macular degeneration (nAMD)

AIMS

To identify baseline characteristics that best correlate to treatment interval for naive neovascular age-related macular degeneration patients treated with faricimab in the first year (Y1) of the TENAYA and LUCERNE phase 3 trials, and to further understand how these characteristics may impact treatment intervals.

METHODS

This post-hoc analysis of Y1 data from the TENAYA and LUCERNE trials evaluated ocular baseline characteristics associated with Y1 treatment intervals. Patients were categorised into three subgroups based on their Y1 treatment interval: Q16W, Q12W or Q8W. Baseline characteristics (central subfield thickness (CST), best-corrected visual acuity, presence of subretinal fluid in centre 1 mm, presence of retinal fluid in centre 1 mm, macular neovascularisation (MNV) location and MNV type) were inputted into an R package 'rpart' to create a classification tree model. A data-driven tree model based on CST was fitted, producing CST subgroups of low, middle and high ranges. Within each CST subgroup, the model identified the most impactful variables and associated thresholds.

RESULTS

After fitting the data to produce data-driven CST ranges, the model chose MNV location, followed by MNV lesion type as the most impactful baseline characteristics with these factors having a p value <0.05 in a multivariate analysis.

CONCLUSIONS

Among the selected ocular baseline characteristics from TENAYA and LUCERNE trial, CST, MNV type and MNV location were seen as the most relevant variables to enable extension of treatment intervals during Y1. While this analysis provides insights for treatment intervals during the first year, further analysis incorporating Y2 data from the TENAYA and LUCERNE studies will be needed to assess factors influencing treatment intervals over a longer period.

Protective Effects of Purple Corn (Zea mays L.) Byproduct Extract on Blue Light-Induced Retinal Damage in A2E-Accumulated ARPE-19 Cells

This study investigated the antioxidative characteristics of Zea mays L. purple corn cob and husk extract (PCHE) and its potential protective effects against blue light (BL)-induced damage in N-retinylidene-N-retinylethanolamine (A2E)-accumulated ARPE-19 retinal pigment epithelial cells. PCHE had a 2,2-diphenyl-1-picrylhydrazyl radical-scavenging capacity and Trolox equivalent antioxidant capacity of 1.28±0.43 mM Trolox equivalents (TE)/g and 2,545.41±34.13 mM TE/g, respectively. Total content of anthocyanins, polyphenols, and flavonoids in the PCHE was 11.13±0.10 mg cyanidin-3-glucoside equivalents/100 g, 227.90±7.38 mg gallic acid equivalents/g, and 117.75±2.46 mg catechin equivalents/g, respectively. PCHE suppressed the accumulation of A2E and the photooxidation caused by BL in a dose-dependent manner. After initial treatment with 25 µM/mL A2E and BL, ARPE-19 cells showed increased cell viability following additional treatment with 15 µg/mL PCHE while the expression of the p62 sequestosome 1 decreased, whereas that of heme oxygenase-1 protein increased compared with that in cells without PCHE treatment. This suggests that PCHE may slow the autophagy induced by BL exposure in A2E-accumulated retinal cells and protect them against oxidative stress.

Exploring retinal degenerative diseases through CRISPR-based screening

The CRISPR (Clustered regularly interspaced short palindromic repeats)/Cas9 (CRISPR-associated protein9) system has emerged as a powerful genetic tool, gaining global recognition as a versatile and efficient gene-editing technique. Its transformation into a high-throughput research platform, CRISPR Screening, has demonstrated wide applicability across various fields such as cancer biology, virology, and drug target discovery, resulting in significant advances. However, its potential in studying retinal degenerative diseases remains largely unexplored, despite the urgent need for effective treatments arising from an incomplete understanding of disease mechanisms. This review aims to present a comprehensive overview of the evolution and current state of CRISPR tools and CRISPR screening methodologies. Noteworthy pioneering studies utilizing these technologies are discussed, alongside experimental design guidelines, including positive and negative selection strategies and delivery methods for sgRNAs (single guide RNAs) and Cas proteins. Furthermore, we explore existing in vitro models appropriate for CRISPR screening in retinal research and identify relevant research questions that could be addressed through this approach. It is anticipated that this review will stimulate innovation in retinal research, facilitating a deeper comprehension of retinal pathophysiology and paving the way for groundbreaking therapeutic interventions and enhanced patient outcomes in the management of retinal degenerative disorders.

Clustered ARPE-19 cells distinct in mitochondrial membrane potential may play a pivotal role in cell differentiation

Age-related macular degeneration (AMD) is associated with the dysfunction and degeneration of retinal pigment epithelium (RPE) cells. Here, we examined how the formation and expansions of cell clusters are regulated by the differentiation of the RPE　cells. In this study, ARPE-19 cells were cultivated in standard or differentiation media, i.e., without or with nicotinamide, to evaluate the spreading of cell clusters specified with differentiated cell phenotypes. Mitochondria membrane potential (MMP) and the distribution of the RPE cell clusters was also monitored with or without rotenone, a mitochondrial electron transport chain (ETC) complex I inhibitor. Cultured ARPE-19 cells generated scattered cell clusters composed mostly of smaller size cells expressing the differentiation markers mouse anti-cellular retinaldehyde-binding protein (CRALBP) and Bestrophin only in differentiation medium. After the increase of the number of clusters, the clusters appeared to paracellularly merge, resulting in expansion of the area occupied by the clusters. Of note, the cells within the clusters selectively had high MMP and were in accordance with the expression of RPE differentiation markers. Rotenone repressed the formation of the clusters and decreased intracellular MMP. The above results suggest that clustering of RPE cells with functional mitochondria plays a pivotal role in RPE cell differentiation process and the ETC complex I inhibition greatly influences the composition of RPE cells that are degenerated or differentiation disposed.

RNASeq profiling of retinal pigment epithelial cells derived from induced pluripotent stem cells revealed 3 genes involved in lipid homeostasis in age-related macular degeneration

Age-related macular degeneration (AMD) is characterized by visual impairment observed in elderly population. Two forms of the disease are generally described, the atrophic (AMDa) and exudative forms (AMDe). Up until now, no curative treatment is available for this disease. The retinal pigment epithelium (RPE) plays a central role in the pathogenesis of age-related macular degeneration. Here, involvement of RPE dysfunction in AMD onset and progression was analyzed by a comparison of transcriptome profiles of hiPSC-RPE derived from healthy individuals or individuals affected by AMDa or AMDe. The analysis highlighted almost 1000 genes differentially expressed between the three comparison groups. Among these genes, 33 genes were already known to be involved in AMD pathogenesis. To establish an AMD genetic signature, we focused on genes differentially expressed in both AMDa/e cell lines compared to control cells and focused on the three genes (ABCA1, RPN2, RB1CC1) that were related to lipidic homeostasis. Differences in level expression of these three genes are found not only in control and AMDa/e cell lines, but also between AMDa and AMDe populations.

Single-cell RNA Sequencing Identifies Natural Kill Cell-Related Transcription Factors Associated With Age-Related Macular Degeneration

Background

Age-related Macular Degeneration (AMD) poses a growing global health concern as the leading cause of central vision loss in elderly people.

Objection

This study focuses on unraveling the intricate involvement of Natural Killer (NK) cells in AMD, shedding light on their immune responses and cytokine regulatory roles.

Methods

Transcriptomic data from the Gene Expression Omnibus database were utilized, employing single-cell RNA-seq analysis. High-dimensional weighted gene co-expression network analysis (hdWGCNA) and single-cell regulatory network inference and clustering (SCENIC) analysis were applied to reveal the regulatory mechanisms of NK cells in early-stage AMD patients. Machine learning models, such as random forests and decision trees, were employed to screen hub genes and key transcription factors (TFs) associated with AMD.

Results

Distinct cell clusters were identified in the present study, especially the T/NK cluster, with a notable increase in NK cell abundance observed in AMD. Cell-cell communication analyses revealed altered interactions, particularly in NK cells, indicating their potential role in AMD pathogenesis. HdWGCNA highlighted the turquoise module, enriched in inflammation-related pathways, as significantly associated with AMD in NK cells. The SCENIC analysis identified key TFs in NK cell regulatory networks. The integration of hub genes and TFs identified CREM, FOXP1, IRF1, NFKB2, and USF2 as potential predictors for AMD through machine learning.

Conclusion

This comprehensive approach enhances our understanding of NK cell dynamics, signaling alterations, and potential predictive models for AMD. The identified TFs provide new avenues for molecular interventions and highlight the intricate relationship between NK cells and AMD pathogenesis. Overall, this study contributes valuable insights for advancing our understanding and management of AMD.

Granzyme B degrades extracellular matrix and promotes inflammation and choroidal neovascularization

Age-related macular degeneration (AMD) is a common retinal neurodegenerative disease among the elderly. Neovascular AMD (nAMD), a leading cause of AMD-related blindness, involves choroidal neovascularization (CNV), which can be suppressed by anti-angiogenic treatments. However, current CNV treatments do not work in all nAMD patients. Here we investigate a novel target for AMD. Granzyme B (GzmB) is a serine protease that promotes aging, chronic inflammation and vascular permeability through the degradation of the extracellular matrix (ECM) and tight junctions. Extracellular GzmB is increased in retina pigment epithelium (RPE) and mast cells in the choroid of the healthy aging outer retina. It is further increased in donor eyes exhibiting features of nAMD and CNV. Here, we show in RPE-choroidal explant cultures that exogenous GzmB degrades the RPE-choroid ECM, promotes retinal/choroidal inflammation and angiogenesis while diminishing anti-angiogenic factor, thrombospondin-1 (TSP-1). The pharmacological inhibition of either GzmB or mast-cell degranulation significantly reduces choroidal angiogenesis. In line with our in vitro data, GzmB-deficiency reduces the extent of laser-induced CNV lesions and the age-related deterioration of electroretinogram (ERG) responses in mice. These findings suggest that targeting GzmB, a serine protease with no known endogenous inhibitors, may be a potential novel therapeutic approach to suppress CNV in nAMD.

Recent Updates on the Diagnosis and Management of Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of irreversible blindness in the Western world, with a higher prevalence among Europeans and North Americans than that in Africans, Hispanics, and Asians. Advanced AMD is categorized as atrophic (dry) or exudative (wet/neovascular age-related macular degeneration [nAMD]). Dry AMD is characterized by progressive geographic atrophy of the retinal pigment epithelium and outer retinal layers, whereas nAMD is characterized by new vessels that invade the subretinal and/or subretinal pigment epithelium spaces. Existing treatments delay the onset of advanced AMD and reverses vision loss for a couple of years before atrophy usually decreases central visual acuity. We searched PubMed and Medline databases from January 1, 1980, to December 1, 2023, using the following search terms: macular degeneration, choroidal neovascularization, geographic atrophy, drusen, age-related maculopathy, AMD, ARMD, and anti-VEGF. Relevant articles in English (or English translations) were retrieved and reviewed. Bibliographies of the identified manuscripts were also reviewed to identify relevant studies. Age-related macular degeneration most commonly affects people older than 55 years. Visual prognosis varies, with advanced lesions (nAMD and geographic atrophy) leading to rapid, progressive loss of central vision and contrast sensitivity. Although AMD is not a life-threatening disease, reduced vision profoundly compromises quality of life and necessitates living assistance for many patients. Over the past 2 decades, advances in prevention (vitamin supplementation) and therapy (antivascular endothelial growth factor and complement inhibitor drugs) have reduced vision loss and blindness. Further research is needed to decrease the incidence of blindness in patients with advanced disease.

Switching to Intravitreal Brolucizumab after Ranibizumab or Aflibercept Using Treat and Extend Regimen for Neovascular Age-Related Macular Degeneration in Japanese Patients: 1-Year Results and Factors Associated with Treatment Responsiveness

Objective: To purpose of this study was to retrospectively evaluate the 1-year outcomes and factors associated with the treatment responsiveness of switching to intravitreal brolucizumab (IVBR) for neovascular age-related macular degeneration (nAMD) in Japanese patients refractory to ranibizumab or aflibercept using a treat and extend (TAE) regimen. Methods: A total of 48 eyes of 47 nAMD patients were switched to IVBR, and 36 eyes of 35 patients (27 males and 8 females) underwent 1-year treatment after the switch. Results: The rate of dry macula was significantly higher 12 months after the switch to IVBR (p < 0.001), with a significant decrease in the mean central macular thickness (CMT) and the mean central choroidal thickness (CCT) (p < 0.01 and p < 0.01, respectively). The injection interval was significantly extended from 7.0 ± 1.7 weeks to 10.3 ± 2.5 weeks 12 months after the switch (p < 0.001). In the multivariate analysis, a smaller number of prior anti-VEGF injections (p = 0.025; odds ratio: 0.947; 95% confidence interval: 0.903-0.994) and a pre-switching CCT of less than 250 µm (p = 0.023; odds ratio: 0.099; 95% confidence interval: 0.013-0.731) were associated with the good response group. Conclusions: These results suggest that IVBR may suppress disease activity and prolong the injection interval by switching for AMD patients with an insufficient response to treatment with ranibizumab and aflibercept.

Identification of the CDH18 gene associated with age-related macular degeneration using weighted gene co-expression network analysis

Purpose: Age-related macular degeneration (AMD) is a chronic and progressive macular degenerative disease that culminates in a gradual deterioration of central vision. Despite its prevalence, the key biomarkers for AMD have not yet been fully elucidated. In this study, we aimed to efficiently identify biomarkers crucial for diagnosing AMD. Methods: Three datasets pertaining to retinal pigment epithelium (RPE)/choroid tissues associated with AMD were selected from the GEO database. The GSE50195 dataset was utilized to conduct weighted gene co-expression network analysis (WGCNA) for identifying module genes linked to AMD. KEGG and GO enrichment analyses were subsequently conducted on these module genes. GSE29801 and GSE135092 datasets were subjected to differential expression analysis to pinpoint the DEGs intersecting with the module genes. Subsequently, wet AMD (wAMD) and dry AMD (dAMD) mouse models were developed, from which RPE/choroid tissues were harvested to validate the hub genes via RT-qPCR and Western blot. Results: Using the WGCNA, we selected the "antiquewhite4" module (r = 0.91 and p = 7e-07), which contains a total of 325 genes. Through the intersection of module genes with DEGs, nine hub genes were identified. Pathways involved in complement and coagulation cascades, ECM-receptor interactions, unsaturated fatty acid biosynthesis, and fatty acid elongation play important roles in AMD. Notably, CDH18 demonstrated notable variance across all three datasets. Post validation using RT-qPCR experiments revealed a significant downregulation of CDH18 in both dAMD and wAMD. EGLN3 was expressed at low levels in wAMD. In dAMD, EYA2, LTB, and PODXL were significantly downregulated, whereas APOC1 was notably upregulated. Western blot confirmed that CDH18 was lowly expressed in dAMD and wAMD mouse models. Conclusion: CDH18 was identified as the key gene involved in the pathogenesis of AMD. An imbalance of the complement and coagulation cascades is a potential mechanism of AMD. This study provides a novel idea for diagnosing and treating AMD in the future.

Olink Profiling of Aqueous Humor Identifies Novel Biomarkers for Wet Age-Related Macular Degeneration

Metabolic dysfunction is recognized as a contributing factor in the pathogenesis of wet age-related macular degeneration (wAMD). However, the specific metabolism-related proteins implicated in wAMD remain elusive. In this study, we assessed the expression profiles of 92 metabolism-related proteins in aqueous humor (AH) samples obtained from 44 wAMD patients and 44 cataract control patients. Our findings revealed significant alterations in the expression of 60 metabolism-related proteins between the two groups. Notably, ANGPTL7 and METRNL displayed promising diagnostic potential for wAMD, as evidenced by area under the curve values of 0.88 and 0.85, respectively. Subsequent validation studies confirmed the upregulation of ANGPTL7 and METRNL in the AH of wAMD patients and in choroidal neovascularization (CNV) models. Functional assays revealed that increased ANGPTL7 and METRNL played a pro-angiogenic role in endothelial biology by promoting endothelial cell proliferation, migration, tube formation, and spouting in vitro. Moreover, in vivo studies revealed the pro-angiogenic effects of ANGPTL7 and METRNL in CNV formation. In conclusion, our findings highlight the association between elevated ANGPTL7 and METRNL levels and wAMD, suggesting their potential as novel predictive and diagnostic biomarkers for this condition. These results underscore the significance of ANGPTL7 and METRNL in the context of wAMD pathogenesis and offer new avenues for future research and therapeutic interventions.

Human amniotic mesenchymal stem cells-derived conditioned medium and exosomes alleviate oxidative stress-induced retinal degeneration by activating PI3K/Akt/FoxO3 pathway

Age-related macular degeneration (AMD) is the leading cause of vision loss among the elderly, which is primarily attributed to oxidative stress-induced damage to the retinal pigment epithelium (RPE). Human amniotic mesenchymal stem cells (hAMSC) were considered to be one of the most promising stem cells for clinical application due to their low immunogenicity, tissue repair ability, pluripotent potential and potent paracrine effects. The conditional medium (hAMSC-CM) and exosomes (hAMSC-exo) derived from hAMSC, as mediators of intercellular communication, play an important role in the treatment of retinal diseases, but their effect and mechanism on oxidative stress-induced retinal degeneration are not explored. Here, we reported that hAMSC-CM alleviated H2O2-induced ARPE-19 cell death through inhibiting mitochondrial-mediated apoptosis pathway in vitro. The overproduction of reactive oxygen species (ROS), alteration in mitochondrial morphology, loss of mitochondrial membrane potential and elevation of Bax/Bcl2 ratio in ARPE-19 cells under oxidative stress were efficiently reversed by hAMSC-CM. Moreover, it was found that hAMSC-CM protected cells against oxidative injury via PI3K/Akt/FoxO3 signaling. Intriguingly, exosome inhibitor GW4869 alleviated the inhibitory effect of hAMSC-CM on H2O2-induced decrease in cell viability of ARPE-19 cells. We further demonstrated that hAMSC-exo exerted the similar protective effect on ARPE-19 cells against oxidative damage as hAMSC-CM. Additionally, both hAMSC-CM and hAMSC-exo ameliorated sodium iodate-induced deterioration of RPE and retinal damage in vivo. These results first indicate that hAMSC-CM and hAMSC-exo protect RPE cells from oxidative damage by regulating PI3K/Akt/FoxO3 pathway, suggesting hAMSC-CM and hAMSC-exo will be a promising cell-free therapy for the treatment of AMD in the future.

CYTOR-NFAT1 feedback loop regulates epithelial-mesenchymal transition of retinal pigment epithelial cells

Epithelial mesenchymal transition (EMT) occurring in retinal pigment epithelial cells (RPE) is a crucial mechanism that contributes to the development of age-related macular degeneration (AMD), a pivotal factor leading to permanent vision impairment. Long non-coding RNAs (lncRNAs) have emerged as critical regulators orchestrating EMT in RPE cells. In this study, we explored the function of the lncRNA CYTOR (cytoskeleton regulator RNA) in EMT of RPE cells and its underlying mechanisms. Through weighted correlation network analysis, we identified CYTOR as an EMT-related lncRNA associated with AMD. Experimental validation revealed that CYTOR orchestrates TGF-β1-induced EMT, as well as proliferation and migration of ARPE-19 cells. Further investigation demonstrated the involvement of CYTOR in regulating the WNT5A/NFAT1 pathway and NFAT1 intranuclear translocation in the ARPE-19 cell EMT model. Mechanistically, CHIP, EMSA and dual luciferase reporter assays confirmed NFAT1's direct binding to CYTOR's promoter, promoting transcription. Reciprocally, CYTOR overexpression promoted NFAT1 expression, while NFAT1 overexpression increased CYTOR transcription. These findings highlight a mutual promotion between CYTOR and NFAT1, forming a positive feedback loop that triggers the EMT phenotype in ARPE-19 cells. These discoveries provide valuable insights into the molecular mechanisms of EMT and its association with AMD, offering potential avenues for targeted therapies in EMT-related conditions, including AMD.

Exudative Age-Related Macular Degeneration: Association between Treatment Efficacy and Single-Nucleotide Variants in RAD51B, TRIB1, COL8A1, COL10A1, IL-9, IL-10, and VEGFA Genes

Age-related macular degeneration (AMD) is a progressive neurodegenerative condition leading to vision loss and eventual blindness, with exudative AMD posing a heightened risk due to choroidal neovascularization and localized edema. Therapies targeting the VEGF pathway aim to address this mechanism for treatment effectiveness. Our study aimed to evaluate associations between specific genetic variants (RAD51B rs8017304, rs2588809; TRIB1 rs6987702, rs4351379; COL8A1 rs13095226; COL10A1 rs1064583; IL-9 rs1859430, rs2069870, rs11741137, rs2069885, rs2069884; IL-10 rs1800871, rs1800872, rs1800896; VEGFA rs1570360, rs699947, rs3025033, rs2146323) and the response to anti-VEGF treatment for exudative AMD. We enrolled 119 patients with exudative AMD categorized as responders or non-responders based on their response to anti-VEGF treatment. Statistical analysis revealed that RAD51B rs8017304 heterozygous and homozygous minor allele carriers had increased CMT before treatment compared to wild-type genotype carriers (p = 0.004). Additionally, TRIB1 rs4351379 heterozygous and homozygous minor allele carriers exhibited a greater decrease in central macular thickness (CMT) after 6 months of treatment than wild-type genotype carriers (p = 0.030). IL-9 rs1859430, rs2069870, and rs2069884 heterozygous and homozygous minor allele carriers had worse BCVA before treatment than wild-type genotype carriers (p = 0.018, p = 0.012, p = 0.041, respectively). Conversely, IL-9 rs2069885 heterozygous and homozygous minor allele carriers showed greater improvement in BCVA after 6 months compared to wild-type genotype carriers (p = 0.032). Furthermore, VEGFA rs699947 heterozygous and homozygous minor allele carriers had better BCVA before treatment and after 3 and 6 months of treatment than wild-type genotype carriers (p = 0.003, p = 0.022, respectively), with these carriers also exhibiting higher CMT after 6 months of anti-VEGF treatment (p = 0.032). Not all results remained statistically significant under this stringent correction for multiple comparisons. The comparisons of the serum concentrations of IL-10, VEGF-A, and VEGF-R2/KDR between non-responders and responders did not yield statistically significant differences. Our study identified significant associations between genetic variants, including RAD51B rs8017304, TRIB1 rs4351379, IL-9 rs1859430, rs2069870, rs2069884, rs2069885, and VEGFA rs699947, and parameters related to the efficacy of exudative AMD treatment, such as BCVA and CMT.

Application of mendelian randomization in ocular diseases: a review

Ocular disorders can significantly lower patients' quality of life and impose an economic burden on families and society. However, for the majority of these diseases, their prevalence and mechanisms are yet unknown, making prevention, management, and therapy challenging. Although connections between exposure factors and diseases can be drawn through observational research, it is challenging to rule out the interference of confounding variables and reverse causation. Mendelian Randomization (MR), a method of research that combines genetics and epidemiology, has its advantage to solve this problem and thus has been extensively utilized in the etiological study of ophthalmic diseases. This paper reviews the implementation of MR in the research of ocular diseases and provides approaches for the investigation of related mechanisms as well as the intervention strategies.

Challenges and opportunities of developing small-molecule therapies for age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of vision loss in senior adults. The disease can be categorized into two types: wet AMD and dry AMD. Wet AMD, also known as exudative or neovascular AMD, is less common but more severe than dry AMD and is responsible for 90% of the visual impairment caused by AMD and affects 20 million people worldwide. Current treatment options mainly involve biologics that inhibit the vascular endothelial growth factor or complement pathways. However, these treatments have limitations such as high cost, injection-related risks, and limited efficacy. Therefore, new therapeutic targets and strategies have been explored to improve the outcomes of patients with AMD. A promising approach is the use of small-molecule drugs that modulate different factors involved in AMD pathogenesis, such as tyrosine kinases and integrins. Small-molecule drugs offer advantages, such as oral administration, low cost, good penetration, and increased specificity for the treatment of wet and dry AMD. This review summarizes the current status and prospects of small-molecule drugs for the treatment of wet AMD. These advances are expected to support the development of effective and targeted treatments for patients with AMD.

Potential in exosome-based targeted nano-drugs and delivery vehicles for posterior ocular disease treatment: from barriers to therapeutic application

Posterior ocular disease, a disease that accounts for 55% of all ocular diseases, can contribute to permanent vision loss if left without treatment. Due to the special structure of the eye, various obstacles make it difficult for drugs to reach lesions in the posterior ocular segment. Therefore, the development of highly permeable targeted drugs and delivery systems is particularly important. Exosomes are a class of extracellular vesicles at 30-150 nm, which are secreted by various cells, tissues, and body fluids. They carry various signaling molecules, thus endowing them with certain physiological functions. In this review, we describe the ocular barriers and the biogenesis, isolation, and engineering of exosomes, as exosomes not only have pharmacological effects but also are good nanocarriers with targeted properties. Moreover, their biocompatibility and immunogenicity are better than synthetic nanocarriers. Most importantly, they may have the ability to pass through the blood-eye barrier. Thus, they may be developed as both targeted nano-drugs and nano-delivery vehicles for the treatment of posterior ocular diseases. We focus on the current status and potential application of exosomes as targeted nano-drugs and nano-delivery vehicles in posterior ocular diseases.

Novel CCR3-targeted cyclic peptides as potential therapeutic agents for age-related macular degeneration via inhibiting angiogenesis and reducing retinal photoreceptor damage

The prolonged intravitreal administration of anti-vascular endothelial growth factor (VEGF) drugs is prone to inducing aberrant retinal vascular development and causing damage to retinal neurons. Hence, we have taken an alternative approach by designing and synthesizing a series of cyclic peptides targeting CC motif chemokine receptor 3 (CCR3). Based on the binding mode of the N-terminal region in CCR3 protein to CCL11, we used computer-aided identification of key amino acid sequence, conformational restriction through different cyclization methods, designed and synthesized a series of target cyclic peptides, and screened the preferred compound IB-2 through affinity. IB-2 exhibits excellent anti-angiogenic activity in HRECs. The apoptosis level of 661W cells demonstrated a significant decrease with the escalating concentration of IB-2. This suggests that IB-2 may have a protective effect on photoreceptor cells. In vivo experiments have shown that IB-2 significantly reduces retinal vascular leakage and choroidal neovascularization (CNV) area in a laser-induced mouse model of CNV. These findings indicate the potential of IB-2 as a safe and effective therapeutic agent for AMD, warranting further development.

Potential therapeutic effects of green tea (Camellia sinensis) in eye diseases, a review

This review aims to evaluate the therapeutic potential of green tea (GT), scientifically named Camellia sinensis, in treating eye diseases. We provide an overview of the ingredients and traditional use of Camellia sinensis, followed by a detailed discussion of its therapeutic uses in various eye diseases, including ocular surface diseases (allergic diseases, dry eye, pterygium, and infections), cataract, glaucoma, uveitis, retinal diseases, and optic nerve diseases. The pharmacologic activities related to ocular diseases, such as anti-vascular endothelial growth factor, aldose reductase inhibitor activity, anti-bacterial, anti-inflammatory, and antioxidant effects are also explored in this review. The dose and route of administration of GT in various studies are discussed. Safety issues related to the use of GT, such as the side effects associated with high doses and long-term use, are also addressed. The review highlights the potential of GT as a natural therapeutic agent for a variety of ocular diseases. Its various pharmacologic activities make it a promising treatment option. However, more well-designed studies are needed to determine the optimal dose and route of administration and to assess its long-term safety and efficacy. Overall, GT appears to be a promising adjunct therapy for various ocular diseases.

Understanding the Impact of Polyunsaturated Fatty Acids on Age-Related Macular Degeneration: A Review

Age-related Macular Degeneration (AMD) is a multifactorial ocular pathology that destroys the photoreceptors of the macula. Two forms are distinguished, dry and wet AMD, with different pathophysiological mechanisms. Although treatments were shown to be effective in wet AMD, they remain a heavy burden for patients and caregivers, resulting in a lack of patient compliance. For dry AMD, no real effective treatment is available in Europe. It is, therefore, essential to look for new approaches. Recently, the use of long-chain and very long-chain polyunsaturated fatty acids was identified as an interesting new therapeutic alternative. Indeed, the levels of these fatty acids, core components of photoreceptors, are significantly decreased in AMD patients. To better understand this pathology and to evaluate the efficacy of various molecules, in vitro and in vivo models reproducing the mechanisms of both types of AMD were developed. This article reviews the anatomy and the physiological aging of the retina and summarizes the clinical aspects, pathophysiological mechanisms of AMD and potential treatment strategies. In vitro and in vivo models of AMD are also presented. Finally, this manuscript focuses on the application of omega-3 fatty acids for the prevention and treatment of both types of AMD.

Understanding the Impact of the Sirtuin 1 (SIRT1) Gene on Age-related Macular Degeneration: A Comprehensive Study

Age-related macular degeneration (AMD) is a prevalent and incurable condition affecting the central retina and posing a significant risk to vision, particularly in individuals over the age of 60. As the global population ages, the prevalence of AMD is expected to rise, leading to substantial socioeconomic impacts and increased healthcare costs. The disease manifests primarily in two forms, neovascular and non-neovascular, with genetic, environmental and lifestyle factors playing a pivotal role in disease susceptibility and progression. This review article involved conducting an extensive search across various databases, including Google Scholar, PubMed, Web of Science, ScienceDirect, Scopus and EMBASE, to compile relevant case-control studies and literature reviews from online published articles extracted using search terms related to the work. SIRT1, a key member of the sirtuin family, influences cellular processes such as ageing, metabolism, DNA repair and stress response. Its dysregulation is linked to retinal ageing and ocular conditions like AMD. This review discusses the role of SIRT1 in AMD pathology, its association with genetic variants and its potential as a biomarker, paving the way for targeted interventions and personalised treatment strategies. In addition, it highlights the findings of case-control studies investigating the relationship between SIRT1 gene polymorphisms and AMD risk. These studies collectively revealed a significant association between certain SIRT1 gene variants and AMD risk. Further studies with larger sample sizes are required to validate these findings. As the prevalence of AMD grows, understanding the role of SIRT1 and other biomarkers becomes increasingly vital for improving diagnosis, treatment and, ultimately, patient outcomes.

Psychophysical, electrofunctional, and morphological evaluation in naïve neovascular AMD patients treated with intravitreal anti-VEGF

Objectives

The aim of this study was to investigate the retinal morpho-functional characteristics of patients with neovascular wet age-related macular degeneration (nAMD) treated with intravitreal injection (IV) of aflibercept (AFL).

Methods

The study was conducted on 35 patients previously diagnosed with type 1 nAMD who received a fixed-dosing regimen of aflibercept injections over 12 months. The goal was to assess trends in visual abilities over time by measuring visual acuity (VA), contrast sensitivity (CS), visual evoked potentials (VEPs), and spectral domain-optical coherence tomography (SD-OCT). The same psychophysical, electro-functional, and morphological tests administered at baseline (T0) were repeated 4 to 8 weeks after the last aflibercept injection (Tn), resulting in a total of six examinations.

Results

At Tn, all subjects exhibited improved VA for both far and near distances compared to values detected at T0. Similarly, VEP amplitude and latency values at Tn showed a greater P100 improvement than those observed at T0. Additionally, the CS examination at Tn demonstrated improvement, particularly at high spatial stimulation frequencies. The Tn SD-OCT results highlighted a reduction in macular thickness compared to T0 values.

Conclusions

This exploratory research indicates that intravitreal injections of AFL, following a fixed-dosing regimen, represent a valuable therapeutic approach for enhancing visual performance. This conclusion is supported by comprehensive statistical analysis of psychophysical, electro-functional, and morphological examinations within the same group of patients with nAMD, as demonstrated for the first time.

The impact of substrate stiffness on morphological, transcriptional and functional aspects in RPE

Alterations in the structure and composition of Bruch's membrane (BrM) and loss of retinal pigment epithelial (RPE) cells are associated with various ocular diseases, notably age-related macular degeneration (AMD) as well as several inherited retinal diseases (IRDs). We explored the influence of stiffness as a major BrM characteristic on the RPE transcriptome and morphology. ARPE-19 cells were plated on soft ( E = 30 kPa ) or stiff ( E = 80 kPa ) polyacrylamide gels (PA gels) or standard tissue culture plastic (TCP). Next-generation sequencing (NGS) data on differentially expressed small RNAs (sRNAs) and messenger RNAs (mRNAs) were validated by qPCR, immunofluorescence or western blotting. The microRNA (miRNA) fraction of sRNAs grew with substrate stiffness and distinct miRNAs such as miR-204 or miR-222 were differentially expressed. mRNA targets of differentially expressed miRNAs were stably expressed, suggesting a homeostatic effect of miRNAs. mRNA transcription patterns were substrate stiffness-dependent, including components of Wnt/beta-catenin signaling, Microphthalmia-Associated Transcription Factor (MITF) and Dicer. These findings highlight the relevance of mechanical properties of the extracellular matrix (ECM) in cell culture experiments, especially those focusing on ECM-related diseases, such as AMD.

Next generation therapeutics for retinal neurodegenerative diseases

Neurodegenerative diseases affecting the visual system encompass glaucoma, macular degeneration, retinopathies, and inherited genetic disorders such as retinitis pigmentosa. These ocular pathologies pose a serious burden of visual impairment and blindness worldwide. Current treatment modalities include small molecule drugs, biologics, or gene therapies, most of which are administered topically as eye drops or as injectables. However, the topical route of administration faces challenges in effectively reaching the posterior segment and achieving desired concentrations at the target site, while injections and implants risk severe complications, such as retinal detachment and endophthalmitis. This necessitates the development of innovative therapeutic strategies that can prolong drug release, deliver effective concentrations to the back of the eye with minimal systemic exposure, and improve patient compliance and safety. In this review, we introduce retinal degenerative diseases, followed by a discussion of the existing clinical standard of care. We then delve into detail about drug and gene delivery systems currently in preclinical and clinical development, including formulation and delivery advantages/drawbacks, with a special emphasis on potential for clinical translation.

Protective effects of triptolide against oxidative stress in retinal pigment epithelium cells via the PI3K/AKT/Nrf2 pathway: a network pharmacological method and experimental validation

PURPOSE

Among aging adults, age-related macular degeneration (AMD), is a prevalent cause of blindness. Nevertheless, its progression may be halted by antioxidation in retinal pigment epithelium (RPE). The primary effective constituent of Tripterygium wilfordii Hook. F., triptolide (TP), has demonstrated anti-inflammatory, antiproliferative, and antioxidant properties. The mechanics of the protective effect of triptolide against the oxidative damage in retinal pigment epithelial (RPE) were assessed in this study.

METHODS

ARPE-19 cells were pretreated with TP, and then exposed to sodium iodate (SI). First, cell viability was assessed using CCK-8. Subsequently, we measured indicators for cell oxidation including reactive oxygen species (ROS), catalase (CAT), superoxide dismutase (SOD), and malondialdehyde (MDA). Then, we used network pharmacological analysis and molecular docking to explore the signaling pathway of TP. Last, we used western blot, ELISA, and immunofluorescence assays to clarify the potential mechanistic pathways.

RESULTS

The network pharmacology data suggested that TP may inhibit AMD by regulating the PI3K/Akt signaling pathway. Experimental results showed that the potential mechanism is that it regulates the PI3K/Akt pathway and promotes Nrf2 phosphorylation and activation, thereby raising the level of antioxidant factors (HO-1, NQO1) and reducing the generation of ROS, which inhibit oxidative damage.

CONCLUSION

Our findings suggested that the effect of TP on SI-exposed RPE cells principally relies on the regulation of oxidative stress through the PI3K/Akt/Nrf2 signaling pathway.

N6-methyladenosine methylation in ophthalmic diseases: From mechanisms to potential applications

N6-methyladenosine (m6A) modification, as the most common modification method in eukaryotes, is widely involved in numerous physiological and pathological processes, such as embryonic development, malignancy, immune regulation, and premature aging. Under pathological conditions of ocular diseases, changes in m6A modification and its metabolism can be detected in aqueous and vitreous humor. At the same time, an increasing number of studies showed that m6A modification is involved in the normal development of eye structures and the occurrence and progress of many ophthalmic diseases, especially ocular neovascular diseases, such as diabetic retinopathy, age-related macular degeneration, and melanoma. In this review, we summarized the latest progress regarding m6A modification in ophthalmic diseases, changes in m6A modification-related enzymes in various pathological states and their upstream and downstream regulatory networks, provided new prospects for m6A modification in ophthalmic diseases and new ideas for clinical diagnosis and treatment.

Wild and cultivated olive trees: Nutraceutical insights of extra virgin olive oils in cardiovascular and ocular diseases

Extra virgin olive oil (EVOO) from Olea europaea (cultivated olive tree) and the oil obtained from the wild olive variety or acebuche (ACE oil from Olea oleaster) contain an extraordinary number of bioactive molecules. These include oleic acid, sterols, tocopherols, triterpene compounds, and polyphenols. Both oils are known for their healthy properties and are considered to be a nutraceutical tool against cardiovascular diseases, including arterial hypertension, preeclampsia, and ocular diseases such as glaucoma or diabetic retinopathy. The benefits of EVOO and ACE oil stem from their anti-inflammatory, antioxidant, and anti-cancer properties. They also have potential as prebiotic compounds. In this update, we synthesise and illustrate the various characteristics and beneficial effects of olive oils from different varieties of olive trees, with special emphasis on Olea oleaster, also known as Olea europaea, L. var. sylvestris.

Multi-Wavelength Photobiomodulation Ameliorates Sodium Iodate-Induced Age-Related Macular Degeneration in Rats

Age-related macular degeneration (AMD) is a global health challenge. AMD causes visual impairment and blindness, particularly in older individuals. This multifaceted disease progresses through various stages, from asymptomatic dry to advanced wet AMD, driven by various factors including inflammation and oxidative stress. Current treatments are effective mainly for wet AMD; the therapeutic options for dry AMD are limited. Photobiomodulation (PBM) using low-energy light in the red-to-near-infrared range is a promising treatment for retinal diseases. This study investigated the effects of multi-wavelength PBM (680, 780, and 830 nm) on sodium iodate-induced oxidatively damaged retinal tissue. In an in vivo rat model of AMD induced by sodium iodate, multi-wavelength PBM effectively protected the retinal layers, reduced retinal apoptosis, and prevented rod bipolar cell depletion. Furthermore, PBM inhibited photoreceptor degeneration and reduced retinal pigment epithelium toxicity. These results suggest that multi-wavelength PBM may be a useful therapeutic strategy for AMD, mitigating oxidative stress, preserving retinal integrity, and preventing apoptosis.

Advancements in the treatment of geographic atrophy: focus on pegcetacoplan in age-related macular degeneration

Geographic atrophy (GA) is a progressive form of age-related macular degeneration characterized by the degeneration of retinal pigment epithelial cells and photoreceptor death. The dysregulation of the complement cascade has been implicated in GA progression. This review provides a comprehensive overview of the pathophysiology of age-related macular degeneration and GA, discusses current therapeutic options, and focuses on the recent breakthrough drug, pegcetacoplan (SYFOVRE). Pegcetacoplan is a complement inhibitor that selectively targets the C3 complement protein, effectively modulating complement activation. Clinical trials, including the OAKS and DERBY studies, have demonstrated the efficacy of SYFOVRE in reducing the growth of GA lesions compared to placebo. The FDA approval of SYFOVRE as the first and only definitive therapy for GA marks a significant milestone in the management of this debilitating condition. The review also explores potential future treatment strategies, including immune-modulating agents and ocular gene therapy. While SYFOVRE offers new hope for GA patients, further research is needed to evaluate its long-term benefits, safety profile, and optimal treatment regimens.