Age-related macular degeneration: genetics and biology coming together

Innovative gene delivery systems for retinal disease therapy

The human retina, a complex and highly specialized structure, includes multiple cell types that work synergistically to generate and transmit visual signals. However, genetic predisposition or age-related degeneration can lead to retinal damage that severely impairs vision or causes blindness. Treatment options for retinal diseases are limited, and there is an urgent need for innovative therapeutic strategies. Cell and gene therapies are promising because of the efficacy of delivery systems that transport therapeutic genes to targeted retinal cells. Gene delivery systems hold great promise for treating retinal diseases by enabling the targeted delivery of therapeutic genes to affected cells or by converting endogenous cells into functional ones to facilitate nerve regeneration, potentially restoring vision. This review focuses on two principal categories of gene delivery vectors used in the treatment of retinal diseases: viral and non-viral systems. Viral vectors, including lentiviruses and adeno-associated viruses, exploit the innate ability of viruses to infiltrate cells, which is followed by the introduction of therapeutic genetic material into target cells for gene correction. Lentiviruses can accommodate exogenous genes up to 8 kb in length, but their mechanism of integration into the host genome presents insertion mutation risks. Conversely, adeno-associated viruses are safer, as they exist as episomes in the nucleus, yet their limited packaging capacity constrains their application to a narrower spectrum of diseases, which necessitates the exploration of alternative delivery methods. In parallel, progress has also occurred in the development of novel non-viral delivery systems, particularly those based on liposomal technology. Manipulation of the ratios of hydrophilic and hydrophobic molecules within liposomes and the development of new lipid formulations have led to the creation of advanced non-viral vectors. These innovative systems include solid lipid nanoparticles, polymer nanoparticles, dendrimers, polymeric micelles, and polymeric nanoparticles. Compared with their viral counterparts, non-viral delivery systems offer markedly enhanced loading capacities that enable the direct delivery of nucleic acids, mRNA, or protein molecules into cells. This bypasses the need for DNA transcription and processing, which significantly enhances therapeutic efficiency. Nevertheless, the immunogenic potential and accumulation toxicity associated with non-viral particulate systems necessitates continued optimization to reduce adverse effects in vivo . This review explores the various delivery systems for retinal therapies and retinal nerve regeneration, and details the characteristics, advantages, limitations, and clinical applications of each vector type. By systematically outlining these factors, our goal is to guide the selection of the optimal delivery tool for a specific retinal disease, which will enhance treatment efficacy and improve patient outcomes while paving the way for more effective and targeted therapeutic interventions.

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.

Evaluating the outcomes of pluripotent stem-cell-derived photoreceptor transplantation in retinal repair

In recent decades, numerous research groups have focused on restoring visual function through the transplantation of stem cells into animal models of retinal neurodegeneration. Significant advancements in surgical techniques, the maturation of donor cells, and the production of cell suspensions, along with ensuring proper synaptic connectivity with the host environment, are key considerations for the potential implementation of this strategy in clinical practice. In this review, we summarize the latest progress in the transplantation of stem cell-derived photoreceptors, emphasizing the outcomes related to visual function observed in the used animal models. Additionally, we analyze the various methods of stem cell differentiation and the surgical techniques selected for transplanting these photoreceptor precursors. Finally, we report on functional assessments from recent studies to highlight the considerable potential of stem cell-derived photoreceptor transplants as a therapeutic approach for retinal degenerative diseases.

Role of alpha-1 antitrypsin in Bruch's membrane integrity

Alpha-1 antitrypsin (AAT) is a serine protease inhibitor that plays a crucial role in maintaining extracellular matrix integrity. Studies suggest that AAT augmentation therapy may benefit multiple eye diseases, including age-related macular degeneration (AMD). However, the function of endogenous AAT in the eye remains unclear. Here we used genetic knockout mice to study the role of AAT in eye health. We show that loss of AAT results in Bruch's membrane (BrM) thickening driven in part by increased laminin deposition with a concomitant decrease in collagen and elastin, which are two other critical BrM components. Interestingly, BrM remodeling due to excess extracellular protease activity reduced the age-related deposition at the BrM of apolipoprotein E, while increasing complement factor H and lowering secretion of the proangiogenic vascular endothelial growth factor. Despite these changes, the phagocytic function of the retinal pigment epithelium was not affected nor was the expression of genes that partake in photoreceptor cell metabolism. Consistent with loss of AAT resulting in changes that should alleviate AMD pathologies, human AMD donor eyes exhibited lower AAT expression levels in the BrM/choroid layer when compared to healthy donor eyes. Together, the study provides insight into AAT's function and its potential involvement in AMD.

A Systematic Review and Meta-Analysis Association Between Periodontitis and Age-Related Macular Degeneration: Potential for Personalized Approach

Background/Objectives: Periodontitis is a chronic inflammatory disease that leads to systemic low-grade inflammation. Systemic low-grade inflammation has been found in patients with age-related macular degeneration (AMD). In this systematic review and meta-analysis, we evaluated the association between periodontitis and AMD. Methods: We searched 11 scientific literature databases on 16th December 2024 for studies of a diagnosis of periodontitis and prevalent or incident AMD. Eligible studies underwent a qualitative review and meta-analysis of the association. Study selection, data extraction, and risk of bias within studies were made in duplicate by two authors and conferred with a senior author. Results: Seven studies eligible for review included in total 149,217 individuals. Across the seven studies, different study designs, diagnoses and definitions of periodontitis, and diagnosis and definitions of AMD were employed. Our meta-analysis showed an association between periodontitis and AMD with an odds ratio of 1.42 (95% CI: 1.12 to 1.78; p = 0.003). Conclusions: Periodontitis is significantly associated with AMD. Unlike genetic predisposition and high age, which are important risk factors of AMD that cannot be modified, periodontitis is a risk factor that can be treated and potentially eliminated, thus allowing for a personalized approach for risk elimination in AMD. Attention should be given to the dental health of patients at risk of AMD.

Life's Essential 8, Genetic Susceptibility, and the Risk of Age-Related Macular Degeneration: A Prospective Cohort Study

Purpose

We determined the association between Life's Essential 8 (LE8) scores and AMD incidence and ascertained whether genetic susceptibility modifies it.

Methods

This prospective cohort study included 268,634 UK Biobank study participants with high, moderate, or low cardiovascular health based on LE8 scores. High and low cardiovascular health corresponded to the lowest and highest cardiovascular disease risks, respectively. The hazard ratios (HRs) and 95% confidence intervals (CIs) for AMD were estimated using Cox proportional hazards models. The dose-response relationships were evaluated using restricted cubic spline analysis. Stratified analyses using the AMD-polygenic risk score categories were used to assess potential modification. A composite variable combined LE8 and AMD-polygenic risk to examine their joint effects.

Results

Over an average of 13.76 years, 5253 participants developed AMD. Compared with the lowest cardiovascular health, moderate and high cardiovascular health had adjusted HRs of 0.86 (95% CI, 0.76, 0.97) and 0.79 (0.69, 0.91), respectively. Each standard deviation increase in the LE8 score corresponded to an HR of 0.93 (0.91, 0.96). The LE8 behavior (HR = 0.94 [0.91, 0.96]) and biological (HR = 0.97 [0.95, 1.00]) subscale scores were inversely associated with AMD, whereas the blood lipids component was positively associated (HR = 1.07 [1.04, 1.10]). The AMD-polygenic risk and LE8 scores showed no significant interaction. The HR for having low AMD-polygenic risk and high cardiovascular health relative to having high AMD-polygenic risk and low cardiovascular health was 0.47 (0.37, 0.58).

Conclusions

Maintaining good cardiovascular health can reduce AMD incidence regardless of genetic background.

Retinal Vasculopathy and Choroiditis after Pegcetacoplan Injection: Clinicopathologic Support for a Drug Hypersensitivity Reaction

PURPOSE

To report the detailed histopathology of 2 enucleated eyes from 2 patients who developed severe visual loss associated with retinal hemorrhages, vessel sheathing, and vascular nonperfusion after administration of an initial dose of intravitreal pegcetacoplan, and propose, with supportive histopathology, the pathogenesis of the clinical syndrome previously termed hemorrhagic occlusive retinal vasculitis.

DESIGN

Case series.

SUBJECTS

Two enucleated eyes from 2 patients treated with intravitreal pegcetacoplan.

METHODS

Retrospective, multicenter, consecutive clinical-pathologic analysis.

MAIN OUTCOME MEASURES

Histopathologic review and immunophenotypic characterization.

RESULTS

Both patients presented with inflammation and significant vision loss 9 days after the initial injection of pegcetacoplan with no subsequent improvement and underwent enucleation for pain control. Histologic examination of the enucleated eyes (patient 1 at 4 months postinjection and patient 2 at 40 days) revealed extensive vascular thrombosis, retinal hemorrhages and necrosis, and a dense inflammatory infiltrate in the uvea and, variably, the optic nerve, episclera, and muscle tendons composed of predominantly of T cells, macrophages, and eosinophils. Notably, the inflammatory infiltrate was absent from the retina. In addition, 1 eye demonstrated multiple foci of glomerular-like vascular proliferations in the uveal tract and thrombosis with focal recanalization of vessels in the optic nerve.

CONCLUSIONS

Drug-induced, immune-mediated, retinal vasculopathy and choroiditis (DIRVAC) is a rare complication after pegcetacoplan injection. Although some limitations arise in interpretation of histopathologic findings because of compensatory changes in the eyes over time (before enucleation), the authors propose that the combined clinical, histopathologic, and immunohistochemical findings suggest a mixed-type, delayed hypersensitivity reaction as the mechanism of initial injury.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Integration and functionality of human iPSC-derived microglia in a chimeric mouse retinal model

INTRODUCTION

Microglia, the resident immune cells of the central nervous system, play a pivotal role in maintaining homeostasis, responding to injury, and modulating neuroinflammation. However, the limitations of rodent models in accurately representing human microglia have posed significant challenges in the study of retinal diseases.

METHODS

PLX5622 was used to eliminate endogenous microglia in mice through oral and intraperitoneal administration, followed by transplantation of human induced pluripotent stem cell-derived microglia (hiPSC-microglia, iMG) into retinal explants to create a novel ex vivo chimeric model containing xenotransplanted microglia (xMG). The number and proportion of xMG in the retina were quantified using retinal flat-mounting and immunostaining. To evaluate the proliferative capacity and synaptic pruning ability of xMG, the expression of Ki-67 and the phagocytosis of synaptic proteins SV2 and PSD95 was assessed. The chimeric model was stimulated with LPS, and single-cell RNA sequencing (scRNA-seq) was used to analyze transcriptomic changes in iMG and xMG. Mouse IL-34 antibody neutralization experiments were performed, and the behavior of xMG in retinal degenerative Pde6b-/- mice was examined.

RESULTS

We demonstrated that xenotransplanted microglia (xMG) successfully migrated to and localized within the mouse retina, adopting homeostatic morphologies. Our approach achieved over 86% integration of human microglia, which maintained key functions including proliferation, immune responsiveness, and synaptic pruning over a 14-day culture period. scRNA-seq of xMG revealed a shift in microglial signatures compared to monoculture iMG, indicating a transition to a more in vivo-like phenotype. In retinal degenerative Pde6b-/- mice, xMG exhibited activation and migrated toward degenerated photoreceptors.

CONCLUSION

This model provides a powerful platform for studying human microglia in the retinal context, offering significant insights for advancing research into retinal degenerative diseases and developing potential therapeutic strategies. Future applications of this model include using patient-derived iPSCs to investigate disease-specific microglial behaviors, thereby enhancing our understanding of microglia-related pathogenesis.

The AMD-associated genetic polymorphism CFH Y402H confers vulnerability to Hydroquinone-induced stress in iPSC-RPE cells

Introduction

Age-related macular degeneration (AMD), a degenerative disease of the macula, is caused by an interplay of diverse risk factors (genetic predisposition, age and lifestyle habits). One of the main genetic risks includes the Y402H polymorphism in complement Factor H (FH), an inhibitor of complement system activation. There has been, and continues to be, much discussion around the functional consequences of this Y402H polymorphism, whether the soluble FH protein confers its risk association, or if the cells expressing the protein themselves are affected by the genetic alteration. In our study, we examined the cell characteristics of the retinal pigment epithelium (RPE) cells, which play a major role in retinal homeostasis and stability and which are synonymously linked to AMD.

Methods

Here, we employ RPE cells derived from induced pluripotent stem cells (iPSC) generated from donors, carrying either homozygous 402Y (low risk) or 402H (high risk) variants of the CFH gene. RPE cells were treated with Hydroquinone (HQ), a component of cigarette smoke, to induce oxidative damage.

Results

Intriguingly, RPE cells carrying high genetic risk proved more vulnerable to oxidative insult when exposed to HQ, as demonstrated by increased cytotoxicity and caspase activation, compared to the low-risk RPE cells. The exposure of RPE cells to RPE conditioned medium, normal human serum (NHS) and inactivated NHS (iNHS) had minimal impact on cell cytotoxicity and caspase activation, nor did the presence of purified soluble FH rescue the observed effects. Considering the known connection of oxidative stress to proteotoxic stress and degrading processes, we investigated the unfolded protein response (UPR) and autophagy. When exposed to HQ, RPE cells showed an increase in autophagy markers; however, iPSC-RPE cells carrying high genetic risk showed an overall reduced autophagic flux.

Discussion

Our findings suggest that the degree of cellular susceptibility to oxidative stress is not conferred by soluble FH protein and other complement sources, but intercellularly because of the corresponding genetic risk predisposition. Our data support the hypothesis that RPE cells carrying high genetic risk are less resilient to oxidative stress.

High Levels of C5a Are Associated With Reduced Macular Sensitivity in Patients With Myeloproliferative Neoplasms

Purpose

Previous findings indicate that patients with myeloproliferative neoplasms (MPN) exhibit elevated levels of inflammatory biomarkers and have a high prevalence of AMD. In this study, we aim to determine whether drusen and systemic inflammation in patients with MPN affect macular sensitivity in the same manner as in patients with AMD.

Methods

The study was conducted as a prospective cross-sectional study. A total of 139 study eyes of 71 patients were included in this study. We measured macular sensitivity using microperimetry and extracted blood samples to evaluate systemic inflammation markers.

Results

Multilevel linear mixed-effect analysis did not show any difference in macular sensitivity when comparing eyes of MPN patients with AMD to those without drusen (β = -0.254, P = 0.657). However, higher levels of the complement system fragment C5a were significantly correlated with decreased total macular sensitivity (β = -0.561, P = 0.027), irrespective of the presence of drusen.

Conclusions

We found that high levels of the systemic inflammation marker C5a are associated with reduced macular sensitivity, regardless of the presence of visible degenerative changes in the macular area. These findings suggest an early contribution of the complement system to macular sensitivity.

Integrative analysis and knowledgebase construction of key candidate genes and pathways in age-related macular degeneration

Age-related macular degeneration is a retinal disease that severely impacts vision in the older population. Its gene-related heterogeneity has not been fully studied, increasing the burden of precise treatment, prevention and prognosis. Genetic variation and related information were collected, annotated and expanded from multiple related websites, and all the data were integrated into the online platform AMDGKB. Users can visit this database via the following link: http://amdgd.bioinf.org.cn/for their personalized applications knowledge-guided modeling and applications. This study also explored the heterogeneity of ethnicity and AMD subtypes via genetic variation, functional enrichment analysis and protein‒protein interactions. These results suggest that VEGFA, MT2A, CCL2 and SERPINF1 play different roles in the development of AMD in different ethnic groups. The enrichment analysis also revealed differences in the pathogenesis pathways of different ethnic groups and AMD subtypes. This study highlights that genetic heterogeneity needs to be considered in the process of diagnosis and treatment. AMDGKB provides information for investigating the transformation of genetic variation during AMD progression, as well as for future personalized applications in the diagnosis and prognosis of AMD.

The effect of molecular chaperone mediated autophagy on ApoE expression in retinal pigment epithelial cells: Molecular structure and protein action mechanism

Chaperone mediated autophagy (CMA) represents a specialized mechanism of lysosomal protein breakdown, playing a crucial role as a metabolic pathway that helps to regulate and sustain cellular and systemic physiological equilibrium. Within the CMA process, proteins that contain sequences similar to KFERQ are specifically identified by the heat shock cognate protein 70. These proteins are then chaperoned to the lysosomes for subsequent degradation, a process facilitated by the lysosome associated membrane protein 2A. This particular research employed bioinformatics techniques to systematically screen for potential substrates of CMA. ApoE has a KFERQ like motif, which may be a substrate for CMA. Under conditions of starvation, hypoxia, H2O2, PA, and NaIO3, the expression of the rate limiting factor LAMP2A in CMA and ApoE increased significantly (P < 0.05). Under conditions of NaIO3, the expression of CMA related gene mRNA increased significantly (P < 0.05). When we use lysosomal blocker CQ to inhibit CMA activity, the expression level of ApoE in retinal pigment epithelial cells increased, and the difference was statistically significant (P < 0.05). When we inhibit CMA, the accumulation of ApoE in retinal pigment epithelial cells increases and cell viability decreases. When we activate CMA, the accumulation of ApoE decreases and cell viability increases. In retinal pigment epithelial cells, the drusen associated protein ApoE can be degraded through the CMA pathway.

Epigallocatechin gallate ameliorates retinal pigment epithelial cell damage via the CYFIP2 /AKT pathway

Age-related macular degeneration (AMD) is a representative age-related ophthalmic disease, and the pathogenesis of AMD remains unclear. This research intended to determine whether epigallocatechin gallate (EGCG) could alleviate the progression of AMD and the possible mechanism. We constructed three groups of mice (young, aged, and EGCG), and HE and TUNEL staining of retinal tissues was performed to observe the structural changes in the retinal pigment epithelial (RPE) layer and the level of apoptosis, respectively. Through RNA-Sequencing analysis of retinal tissues and by RT-qPCR, GO, KEGG, and literature analyses, we identified cytoplasmic fragile X mental retardation 1-interacting protein 2 (CYFIP2) as a possible effector gene for EGCG action and validated its role by immunofluorescent and western blotting experiments. The CCK-8 and Hoechst 33342 apoptosis assays, and western blotting and qRT-PCR assays showed that EGCG reduced hydrogen peroxide (H2O2)-induced apoptosis in adult human RPE (ARPE-19) cells, and the expression of Cyfip2 was changed accordingly. RNA interference analysis indicated that Cyfip2 knockdown alleviated H2O2-induced ARPE apoptosis, while its overexpression weakened EGCG's protective effect. Western blot analysis showed that Cyfip2 mediated the anti-apoptotic effect of EGCG by modulating the level of protein kinase B (Akt) phosphorylation in ARPE cells, and the activation level of phosphorylated AKT (p-AKT Ser473) in retinal tissue of the EGCG-fed group was higher than that of the aged group. Taken together, this study suggests that EGCG plays a protective role in the development of AMD and the apoptosis of ARPE cells through the Cyfip2/AKT pathway.

Disease Activity and Therapeutic Response to Pegcetacoplan for Geographic Atrophy Identified by Deep Learning-Based Analysis of OCT

PURPOSE

To quantify morphological changes of the photoreceptors (PRs) and retinal pigment epithelium (RPE) layers under pegcetacoplan therapy in geographic atrophy (GA) using deep learning-based analysis of OCT images.

DESIGN

Post hoc longitudinal image analysis.

PARTICIPANTS

Patients with GA due to age-related macular degeneration from 2 prospective randomized phase III clinical trials (OAKS and DERBY).

METHODS

Deep learning-based segmentation of RPE loss and PR degeneration, defined as loss of the ellipsoid zone (EZ) layer on OCT, over 24 months.

MAIN OUTCOME MEASURES

Change in the mean area of RPE loss and EZ loss over time in the pooled sham arms and the pegcetacoplan monthly (PM)/pegcetacoplan every other month (PEOM) treatment arms.

RESULTS

A total of 897 eyes of 897 patients were included. There was a therapeutic reduction of RPE loss growth by 22% and 20% in OAKS and 27% and 21% in DERBY for PM and PEOM compared with sham, respectively, at 24 months. The reduction on the EZ level was significantly higher with 53% and 46% in OAKS and 47% and 46% in DERBY for PM and PEOM compared with sham at 24 months. The baseline EZ-RPE difference had an impact on disease activity and therapeutic response. The therapeutic benefit for RPE loss increased with larger EZ-RPE difference quartiles from 21.9%, 23.1%, and 23.9% to 33.6% for PM versus sham (all P < 0.01) and from 13.6% (P = 0.11), 23.8%, and 23.8% to 20.0% for PEOM versus sham (P < 0.01) in quartiles 1, 2, 3, and 4, respectively, at 24 months. The therapeutic reduction of EZ loss increased from 14.8% (P = 0.09), 33.3%, and 46.6% to 77.8% (P < 0.0001) between PM and sham and from 15.9% (P = 0.08), 33.8%, and 52.0% to 64.9% (P < 0.0001) between PEOM and sham for quartiles 1 to 4 at 24 months.

CONCLUSIONS

Deep learning-based OCT analysis objectively identifies and quantifies PR and RPE degeneration in GA. Reductions in further EZ loss on OCT are even higher than the effect on RPE loss in phase 3 trials of pegcetacoplan treatment. The EZ-RPE difference has a strong impact on disease progression and therapeutic response. Identification of patients with higher EZ-RPE loss difference may become an important criterion for the management of GA secondary to AMD.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Loss of paired immunoglobin-like type 2 receptor B gene associated with age-related macular degeneration impairs photoreceptor function in mouse retina

Genome-wide association studies have uncovered mostly non-coding variants at over 60 genetic loci linked to susceptibility for age-related macular degeneration (AMD). To ascertain the causal gene at the PILRB/PILRA locus, we used a CRISPR strategy to produce germline deletions in the mouse paired immunoglobin-like type 2 receptor (Pilr) genes that encode highly related activating (PILRB) and inhibitory (PILRA) receptors. We show that a combined loss of Pilrb1 and Pilrb2, but not Pilra, leads to an early but relatively stationary defect as the electroretinography (ERG) amplitudes of Pilrb1/2-/- mice exhibit a marked reduction as early as postnatal day 15 and do not show additional significant decrease at 3 and 12-months. No alterations are evident in Müller glia, microglia, bipolar, amacrine and horizontal cells based on immunohistochemistry using cell-type specific markers. PILRB immunostaining is specifically detected at the proximal part of photoreceptor outer segment. Reduced expression of select calcium-regulated phototransduction and synapse-associated proteins, including GCAP1 and 2, PDE6b, AIPL1, PSD95, and CTBP1 indicates dysregulation of calcium homeostasis as a possible mechanism of retinal phenotype in Pilrb1/2-/- mice. Our studies suggest a novel function of PILRB in retinal photoreceptors and an association of PILRB, but not PILRA, with AMD pathogenesis.

DNA Methyltransferase Expression (DNMT1, DNMT3a, and DNMT3b) as a Potential Biomarker in Age-Related Macular Degeneration

Background/Objectives: Age-related macular degeneration (AMD) is a global cause of vision loss, with limited therapeutic options highlighting the need for effective biomarkers. This study aimed to characterize plasma DNA methyltransferase expression (DNMT1, DNMT3A, and DNMT3B) in AMD patients and explore divergent expression patterns across different stages of AMD. Methods: Thirty-eight AMD patients were prospectively enrolled and stratified by disease severity: eAMD, iAMD, nAMD, and aAMD. Comprehensive ophthalmological assessments were performed, including best-corrected visual acuity, digital color fundus photographs, and Spectral Domain Optical Coherence Tomography. Peripheral blood samples were collected for RNA extraction and qRT-PCR to access epigenetic effectors' transcriptional expression, namely DNMT1, DNMT3A, and DNMT3B genes. The collected data were analyzed using IBM SPSS 29. Results:DNMT1 expression was significantly downregulated in late AMD (-0.186 ± 0.341) compared to early/intermediate AMD (0.026 ± 0.246). Within late AMD, aAMD exhibited a marked downregulation of DNMT1 (-0.375 ± 0.047) compared to nAMD (0.129 ± 0.392). DNMT3A and DNMT3B showed similar divergent expression patterns, correlating with disease stage. Conclusions: This study identified stage-specific transcriptional differences in DNMT expression, emphasizing its potential as a biomarker for AMD progression and a target for future research into personalized therapeutic strategies.

Steroid-Nitroxide Hybrid Compound Protects the Retina in a Model of CNV

Nitroxide-based drugs have proven effective in modulating radical-induced oxidative stress by modulating antioxidant enzymes and genes that control distinct immune and anti-inflammatory responses. Due to their reasonable chemical stability and ability to shuttle between oxidized and reduced forms at physiologically relevant redox potentials, nitroxide-based radicals have also proven effective as biological probes of redox status. Herein, we investigated the potential of a unique nitroxide-based antioxidant and anti-inflammatory agent to protect the retina from experimentally induced degeneration. An established rat model of retinal degeneration was used viz. laser-induced choroidal neovascularization (CNV) to study the effects of the hybrid steroidal anti-inflammatory-antioxidant prednisolone 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) nitroxide compound. Vascular endothelial cell distribution at the CNV lesion site was investigated using isolectin B4 fluorescence histology, and the inflammatory response of microglia was investigated using IBA-1 immunohistochemistry. The prednisolone-TEMPO (Pred-TEMPO) hybrid reduced the laser-induced CNV lesion area compared to untreated control rats. These findings demonstrate that nitroxide-based compounds are potential therapeutics for retinal degenerative diseases involving inflammatory and oxidative stress-mediated components, including age-related macular degeneration.

Physiology and pathophysiology of the retinal neuroglia

Neuroglia of the retina are represented by Müller glia, parenchymal astrocytes, microglia and oligodendrocytes mainly associated with the optic nerve. Müller glia are the most numerous glia, endowed with multiple homeostatic functions and indispensable for the retinal morphofunctional organization. Müller cells integrate retinal neurons into individual functional units (known as retinal columns) and act as a living light guide, transmitting photons to photoreceptors. In pathology, retinal neuroglia undergo complex changes, which include upregulation of neuroprotection, reactive gliosis, and functional asthenia. The balance between all these changes defines the progression and outcome of retinal disorders.

Cellular Senescence: An Emerging Player in the Pathogenesis of AMD

Age-related macular degeneration (AMD) is the leading cause of blindness in the aged population. The accumulation of abnormal extracellular drusen deposits between the retinal pigment epithelium (RPE) and Bruch's membrane is a significant driver of AMD pathology. Drusen deposition leads to the degeneration of RPE cells and, subsequently, photoreceptors, driving the disease to its advanced stages and ultimately resulting in complete vision loss. Although the exact mechanisms underlying the AMD pathogenesis are not fully understood, it is hypothesized that the disease begins with the dysfunction of the RPE, triggering the complement and pro-inflammatory cascade. Over the last decade, new findings have implicated the involvement of cellular senescence (CS) in the pathology of age-related disorders. Specifically for AMD, evidence suggests that the senescence of RPE cells may play a role in the pathogenesis of the disease. In this review, we discuss the potential role of senescence in the onset and progression of AMD and propose potential therapeutic interventions that could be developed by targeting senescence.

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.

Dry and neovascular "wet" age-related macular degeneration: Upcoming therapies

The age-related macular degeneration (AMD) field is witnessing promising advancements in therapeutic options. Breakthrough drugs such as pegcetacoplan and avacincaptad have been FDA-approved for dry AMD, marking a significant development as there were no treatment options until August 2023. While several antivascular endothelial growth factor (VEGF) inhibitors have been approved for wet AMD, challenges persist with the need for frequent dosing. New treatments such as gene therapy, cell therapy, WNT pathway agonists, complement inhibitors, and anti-VEGF combination drugs are under development to address these issues. These developments are exciting and hold promise for transforming the field of medicine, offering hope for improved outcomes and enhanced patient care in managing AMD.

C-reactive Protein Levels in Prediction of the Development or the Progression of Agerelated Macular Degeneration in Patients Examined at Tuzla Canton

Background

Age-related macular degeneration (ARMD) is a chronic, incurable, progressive, multifactorial, neurodegenerative disease, which is one of the leading causes of visual impairment, among individuals above 60 years of age in developed countries. Over the past decades, the role of inflammation and CRP in the pathogenesis of ARMD has been investigated.

Objective

The study aimed to investigate the association between inflammation or CRP levels in prediction the development or the progression of ARMD.

Methods

This retrospective-prospective, case-control study, was conducted at the Clinic for Eye Diseases, University Clinical Center Tuzla, from 2020. to 2024. Two group of participants were included in this study. The first group (n=100 patients) consisted of patients diagnosed with different stages of ARMD, and second, control group (n=100 patients) consisted of patients without ARMD. The study included subjects of both sexes, divided into three age categories (≤55; 56-66; ≥67 years). Detailed ocular and systemic evaluations were performed, including fundus examination and OCT angiography. A 5mL sample of venous blood was colected to determine serum CRP levels, for the both group of patients, using latex immunoassay method. Statistical analysis, including Student's t-test, Chi square test and posthoc (Turkey) tests, was conducted using SPSS 26 for Windows, with p<0,05 considered significant.

Results

Out of 100 patients, 34 were having early, 18 intermediate and 48 were having advanced stages of ARMD. The mean serum CRP levels in the ARMD group (8.39±27.22mg/L) were significantly higher compared to the control group, (2.52±5.35mg/L), p=0,000. Also, serum CRP values by age category, between ARMD subjects and the control group, showed statistically significant differences in all age groups: ≤55 p=0.032; 56-66 p=0.019; ≥67 p=0.000. The mean serum CRP levels was 6.6±6.9 mg/L, 10±13.3 mg/L and 16±22.7 mg/L, in early, intermediate and advanced ARMD, respectively. Comparing these CRP values and different stages of ARMD, there were found statistically significant differences between the three stages. Furthermore, these results showed that mean CRP values increase with disease severity.

Conclusion

Based on the obtained results serum CRP levels are significant risk factor in predicting the development and the progression of ARMD. Also, these results emphasize the role of systemic inflammation in the development and progression of ARMD.

Analysis of interleukin-6 gene polymorphism and its serum levels in Indian age-related macular degeneration patients

Background

Age-related macular degeneration (AMD) is a complex condition involving multiple factors. The condition is associated with numerous inflammatory indicators, including cytokines. Single-nucleotide polymorphisms in cytokine genes can also modify gene expression, perhaps contributing to the development of the disease. The objective of the present study was to examine the correlation among IL-6 SNPs (rs1800795, rs1800796, and rs1800797) and the serum levels of IL-6 in AMD patients treated at the Regional Institute of Ophthalmology of Pt. B.D. Sharma PGIMS, Rohtak (Haryana), India.

Methods

This case-control study included 131 patients diagnosed with AMD using precise ophthalmic examinations, such as slit lamp examination, fundoscopy, and ocular coherence tomography. To provide a basis for comparison, we also enlisted 100 healthy individuals as controls. Serum IL-6 protein levels were measured in both patients and controls using an enzyme-linked immunosorbent assay kit (ELISA). Genotyping IL-6 SNPs was performed using the PCR and DNA Sanger sequencing technique.

Results

IL-6 serum levels were considerably elevated in individuals with AMD compared to the control group (p < 0.05). Statistically significant differences were seen in the genotype frequencies of rs1800795 (p = 0.027) and rs1800797 (p = 0.0011) among the AMD patients and the healthy controls. Furthermore, strong correlations were observed between rs1800795 and the likelihood of developing AMD based on the heterozygous (OR = 2.04; p = 0.025), dominant (OR = 1.80; p = 0.035), and over-dominant models (OR = 2.10; p = 0.0094). Additionally, there were notable associations between rs1800797 and vulnerability to AMD through heterozygous (OR = 3.21; p = 0.009), dominant (OR = 2.74; p = 0.004), and over-dominant (OR = 3.11; p = 0.002) models. The rs1800795, rs1800796, and rs1800797 haplotypes C-G-A and G-G-A were linked to an elevated risk of AMD (p = 0.005, p = 0.024. respectively).

Conclusions

Our findings indicated a significant elevation in IL-6 serum levels among the AMD patient group compared to the control group. The interleukin-6 gene polymorphisms rs1800795 and rs1800797 were linked to an elevated risk of AMD in our study population.

Analysis of biofluid metabolomic profiles to the discovery of biomarkers in age-related macular degeneration

OBJECTIVE

Age-related macular degeneration (AMD) is one of the leading causes of irreversible visual impairment and blindness in the elderly. As AMD is a multifactorial disease, it is critical to explore useful biomarkers and pathological pathways underlying it. The purpose of this study is to summarise current metabolic profiles and further identify potential metabolic biomarkers and therapeutic targets in AMD, which could facilitate clinical diagnosis and treatment.

METHODS AND ANALYSIS

Relevant metabolomics studies published before 10 December 2021 were generally reviewed from online resources by two investigators. Studies with sufficient information and data were included in this systematic review and repeatedly identified metabolites were extracted. Pathway and Kyoto Encyclopaedia of Genes and Genomes (KEGG) analyses were performed. The public Gene Expression Omnibus (GEO) database was used for coanalysis with differential metabolites to construct a pathway network via MetaboAnalyst V.5.0.

RESULTS

16 studies were included in our analysis. 24 metabolites were repeatedly detected and regarded as potential biomarkers for AMD. Pathway analysis implied a major role of phenylalanine, tyrosine and tryptophan pathways in AMD pathology. 11 KEGG pathways were enriched, meanwhile, 11 metabolic pathway clusters were identified by coanalysing the differential metabolites and gene profiles using the GEO database.

CONCLUSION

In this study, we summarised 16 metabolomic studies on AMD, and 24 metabolites were identified as potential biofluid biomarkers. This provided novel insights into the pathogenic mechanisms underlying AMD. Further studies are warranted to validate and expand an effective pattern for AMD diagnosis and treatment.

The Potential Causal Association of Apolipoprotein A and B and Age-Related Macular Degeneration: A Mendelian Randomisation Study

BACKGROUND/OBJECTIVES

Research has suggested a potential relationship between apolipoproteins A (ApoA) and B (ApoB) and age-related macular degeneration (AMD). This study explored the potential causal relationship between ApoA/ApoB levels and AMD/AMD subtypes using two-sample Mendelian randomisation (MR).

METHODS

We selected 308 single nucleotide polymorphisms (SNPs) for ApoA and 198 SNPs for ApoB from the UK Biobank data. Summary statistics for AMD were collected from the genome-wide association study of the FinnGen project. We performed two-sample MR to assess the causal effects of ApoA/ApoB on AMD and its subtypes. Potential confounders, including body mass index, C-reactive protein level, and smoking status, were assessed using a multivariable MR analysis.

RESULTS

ApoA showed a significant causal association with AMD (odds ratio [OR] = 1.14, 95% confidence interval [CI] = 1.05-1.25, p = 0.003) and was linked to both dry (p = 0.004) and wet (p = 0.025) AMD. ApoB showed a decreasing trend in dry AMD risk (p = 0.074), though not significant, and was not associated with overall or wet AMD. The multivariable MR analysis showed no significant association of ApoA with any AMD subtype (p > 0.05). ApoB decreased dry AMD risk (OR = 0.89, 95% CI = 0.80-0.99, p = 0.039), with trends for overall and wet AMD that were not significant (p = 0.070 and p = 0.091, respectively).

CONCLUSIONS

These findings suggest that ApoB is associated with lower AMD risk, particularly for dry AMD. Further research is needed to clarify lipid biomarker's role as AMD risk factors.

Potential Use of Plasma Rich in Growth Factors in Age-Related Macular Degeneration: Evidence from a Mouse Model

Background and Objectives: Age-related macular degeneration (AMD) is the leading cause of low vision and legal blindness in adults in developed countries. Wet AMD can be successfully treated using vascular endothelial growth factor (VEGF) inhibitors; however, dry AMD currently has no effective treatment. The purpose of this study is to analyze the efficacy of intraocular injection of plasma rich in growth factors (PRGF) in an AMD mouse model induced by intraperitoneal administration of sodium iodate. Materials and Methods: Intravitreal application of PRGF (experimental group) and saline (control group) was performed immediately after intraperitoneal injection of sodium iodate. Retinographies were performed at 2 and 7 days after treatment administration. The eyes were retrieved for histological and immunohistological analysis. Statistical analysis was performed to compare the outcomes between the study groups. Results: In comparison to saline solution, PRGF significantly decreased the depigmentation of the RPE, showing a more reddened retina. PRGF intravitreal treatment significantly reduced the glial fibrillary acidic protein (GFAP) stained processes, suggesting a significant reduction in the risk of scar formation. Moreover, the myofibroblast invasion into the RPE cell layer was significantly reduced in the PRGF-treated group of mice. There was a tendency for better preservation of the photoreceptors in the PRGF group. Conclusions: Within the limitations of this study, intravitreal injection of PRGF provided significant protection against the degeneration of the photoreceptors and the RPE induced by the systemic administration of NaIO3.

Different Therapeutic Approaches for Dry and Wet AMD

Age-related macular degeneration (AMD) is the most common cause of irreversible loss of central vision in elderly subjects, affecting men and women equally. It is a degenerative pathology that causes progressive damage to the macula, the central and most vital part of the retina. There are two forms of AMD depending on how the macula is damaged, dry AMD and wet or neovascular AMD. Dry AMD is the most common form; waste materials accumulate under the retina as old cells die, not being replaced. Wet AMD is less common, but can lead to vision loss much more quickly. Wet AMD is characterized by new abnormal blood vessels developing under the macula, where they do not normally grow. This frequently occurs in patients who already have dry AMD, as new blood vessels are developed to try to solve the problem. It is not known what causes AMD to develop; however, certain risk factors (i.e., age, smoking, genetic factors) can increase the risk of developing AMD. There are currently no treatments for dry AMD. There is evidence that not smoking, exercising regularly, eating nutritious food, and taking certain supplements can reduce the risk of acquiring AMD or slow its development. The main treatment for wet AMD is inhibitors of VEGF (vascular endothelial growth factor), a protein that stimulates the growth of new blood vessels. VEGF inhibitors can stop the growth of new blood vessels, preventing further damage to the macula and vision loss. In most patients, VEGF inhibitors can improve vision if macular degeneration is diagnosed early and treated accordingly. However, VEGF inhibitors cannot repair damage that has already occurred. Current AMD research is trying to find treatments for dry AMD and other options for wet AMD. This review provides a summary of the current evidence regarding the different treatments aimed at both forms of AMD with particular and greater attention to the dry form.

A deep learning approach to explore the association of age-related macular degeneration polygenic risk score with retinal optical coherence tomography: A preliminary study

PURPOSE

Age-related macular degeneration (AMD) is a complex eye disorder affecting millions worldwide. This article uses deep learning techniques to investigate the relationship between AMD, genetics and optical coherence tomography (OCT) scans.

METHODS

The cohort consisted of 332 patients, of which 235 were diagnosed with AMD and 97 were controls with no signs of AMD. The genome-wide association studies summary statistics utilized to establish the polygenic risk score (PRS) in relation to AMD were derived from the GERA European study. A PRS estimation based on OCT volumes for both eyes was performed using a proprietary convolutional neural network (CNN) model supported by machine learning models. The method's performance was assessed using numerical evaluation metrics, and the Grad-CAM technique was used to evaluate the results by visualizing the features learned by the model.

RESULTS

The best results were obtained with the CNN and the Extra Tree regressor (MAE = 0.55, MSE = 0.49, RMSE = 0.70, R2 = 0.34). Extending the feature vector with additional information on AMD diagnosis, age and smoking history improved the results slightly, with mainly AMD diagnosis used by the model (MAE = 0.54, MSE = 0.44, RMSE = 0.66, R2 = 0.42). Grad-CAM heatmap evaluation showed that the model decisions rely on retinal morphology factors relevant to AMD diagnosis.

CONCLUSION

The developed method allows an efficient PRS estimation from OCT images. A new technique for analysing the association of OCT images with PRS of AMD, using a deep learning approach, may provide an opportunity to discover new associations between genotype-based AMD risk and retinal morphology.

Role of inflammation in diabetic macular edema and neovascular age-related macular degeneration

Diabetic macular edema (DME) and neovascular age-related macular degeneration (nAMD) are multifactorial disorders that affect the macula and cause significant vision loss. Although inflammation and neoangiogenesis are hallmarks of DME and nAMD, respectively, they share some biochemical mediators. While inflammation is a trigger for the processes that lead to the development of DME, in nAMD inflammation seems to be the consequence of retinal pigment epithelium and Bruch membrane alterations. These pathophysiologic differences may be the key issue that justifies the difference in treatment strategies. Vascular endothelial growth factor inhibitors have changed the treatment of both diseases, however, many patients with DME fail to achieve the established therapeutic goals. From a clinical perspective, targeting inflammatory pathways with intravitreal corticosteroids has been proven to be effective in patients with DME. On the contrary, the clinical relevance of addressing inflammation in patients with nAMD has not been proven yet. We explore the role and implication of inflammation in the development of nAMD and DME and its therapeutical relevance.

The interactions between ARMS2, CFH, VEGF-A and environmental factors on the risk of age-related macular degeneration

Background

Age related macular degeneration (AMD) is a multifactorial disease caused by a combination of environmental and genetic factors. The prevalence of allele and genotypeof AMD-related genes is varied throughout the world due to racial and ethnic differences. Number of previous studies have shown that the polymorphisms in the ARMS2, CFH and VEGF-A genes are associated with AMD. In Mongolia, there is a lack of sufficient data on AMD development in its population and thus needs more studies on the topic. Therefore, it needs more studies about AMD development in the population. For this reason, we have investigated several specified polymorphisms in CFH, VEGF-A and ARMS2 genes to reveal a relationship with AMD and determine the prevalence of alleles and genotypes of the genes in Mongolian population.

Methods

Totally 161 AMD patients and 223 controls were enrolled in this case-control study. The polymorphisms in CFH, ARMS2 and VEGF-A were detected by using the methods of allele-specific polymerase chain reaction (ASPCR) and PCR based restriction fragment length polymorphism (RFLP). Statistical analysis were performed by STATA 13.0, SNPAlyze 9.0 and MDR 3.0.2.

Results

According to the study result, the characteristics of hypertension, constant-wearing sunglasses and anticoagulant medications in AMD group were significantly different from those in the control group. As for the dominant model, T allele of ARMS2 rs10490924 (cOR=4.45; 95% CI, 2.44-8.13, p<0.001, aOR=5.08; 95% CI, 2.70-9.59, p<0.001) was more frequent among patients with AMD in comparison with the control group. Also, G/G genotype of CFH rs800292 (cOR=11.61; 95% CI, 3.41-39.51, p<0.001, aOR=12.49; 95% CI, 3.47-44.91, p<0.001) and G/G genotype of CFH rs1065489 (cOR=4.19; 95% CI, 2.53-6.93, p<0.001, aOR=4.67; 95% CI, 2.71-8.05, p<0.001) were significantly higher in AMD group after Bonferroni correction. This result suggests that people who carrying the risk genotypes of these polymorphisms had an increased risk for AMD development. As for the models of three or more SNP interactions, the participants with any combinations of risk genotypes have 6 to 106-fold higher risk for AMD development. This result suggests that there is some positive-additive interaction existing between the genetic variants of ARMS2, CFH and VEGF-A genes for AMD development. Our study also revealed that the participants with hypertension and carrying G/G for rs1065489 in CFH gene or non G/G for rs10490924 in ARMS2 gene genotypes had 9 to 14 times higher risk for AMD development (cOR=9.05; 95% CI, 4.38-18.68, p<0.001, RERI=4.546; AP=0.502, S=2.298, cOR=13.98; 95% CI, 3.19-61.1, p<0.001, RERI=5.85; AP=0.419, S=1.821) with high level of significance. Moreover, it was found that the participants who avoided wearing sunglasses and had the G/G genotype of ARMS2 rs10490924 or G/G genotype of CFH rs800292 had an extremely higher risk for AMD development (p<.001).

Conclusions

In conclusion, it was observed that the combination of SNPs in ARMS2, CFH and VEGF-A genes increase the risk for AMD with 6 to 106-fold. Moreover, we found that the participants with hypertension and carrying the non G/G genotype of ARMS2 rs10490924 or the G/G genotype of CFH rs800292 had an extremely higher risk of AMD development.

Role of ARMS2/HTRA1 risk alleles in the pathogenesis of neovascular age-related macular degeneration

Age-related macular degeneration (AMD) is one of the leading causes of severe irreversible blindness worldwide in the elderly population. AMD is a multifactorial disease mainly caused by advanced age, environmental factors, and genetic variations. Genome-wide association studies (GWAS) have strongly supported the link between ARMS2/HTRA1 locus on chromosome 10q26 and AMD development, encompassing multiple variants, rs10490924 (c.205G > T, p.A69S in ARMS2), insertion/deletion (del443/ins54 in ARMS2), and rs11200638 (in HTRA1 promoter region). In this comprehensive review, we provide an overview of the role played by ARMS2/HTRA1 risk alleles in neovascular AMD pathogenesis, covering GWAS, in vitro studies, and animal models, shedding light on their underlying molecular genetic mechanisms. Further extensive research is also imperative, including confirmation of these findings, identifying novel treatment targets, and advancing primary and secondary prevention strategies for AMD.

Retinal Organoid Microenvironment Enhanced Bioactivities of Microglia-Like Cells Derived From HiPSCs

Purpose

Microglia-like cells derived from stem cells (iMG) provide a plentiful cell source for studying the functions of microglia in both normal and pathological conditions. Our goal is to establish a simplified and effective method for generating iMG in a precisely defined system. Additionally, we aim to achieve functional maturation of iMG through coculture with retinal organoids.

Methods

In this study, iMG were produced under precisely defined conditions. They were subjected to LPS and poly IC stimulation. Additionally, we examined distinct phenotypic and functional variances between iMG and HMC3, a commonly used human microglia cell line. To investigate how the retinal cell interaction enhances microglial properties, iMG were cocultured with retinal organoids, producing CC-iMG. We performed RNA sequencing, electrophysiological analysis, and transmission electron microscope (TEM) to examine the maturation of CC-iMG compared to iMG.

Results

Our results demonstrated that iMG performed immune-responsive profiles closely resembling those of primary human microglia. Compared to HMC3, iMG expressed a higher level of typical microglial markers and exhibited enhanced phagocytic activity. The transcriptomic analysis uncovered notable alterations in the ion channel profile of CC-iMG compared to iMG. Electrophysiological examination demonstrated a heightened intensity of inward- and outward-rectifying K+ currents in CC-iMG. Furthermore, CC-iMG displayed elevated numbers of lysosomes and mitochondria, coupled with increased phagocytic activity.

Conclusions

These findings contribute to advancing our understanding of human microglial biology, specifically in characterizing and elucidating the functions of CC-iMG, thereby offering an in vitro microglial model for future scientific research and potential clinical applications in cell therapy.

Aberrant Lipid Metabolism and Complement Activation in Age-Related Macular Degeneration

Age-related macular degeneration (AMD) stands as a leading cause of severe visual impairment and blindness among the elderly globally. As a multifactorial disease, AMD's pathogenesis is influenced by genetic, environmental, and age-related factors, with lipid metabolism abnormalities and complement system dysregulation playing critical roles. This review delves into recent advancements in understanding the intricate interaction between these two crucial pathways, highlighting their contribution to the disease's progression through chronic inflammation, drusen formation, and retinal pigment epithelium dysfunction. Importantly, emerging evidence points to dysregulated lipid profiles, particularly alterations in high-density lipoprotein levels, oxidized lipid deposits, and intracellular lipofuscin accumulation, as exacerbating factors that enhance complement activation and subsequently amplify tissue damage in AMD. Furthermore, genetic studies have revealed significant associations between AMD and specific genes involved in lipid transport and complement regulation, shedding light on disease susceptibility and underlying mechanisms. The review further explores the clinical implications of these findings, advocating for a novel therapeutic approach that integrates lipid metabolism modulators with complement inhibitors. By concurrently targeting these pathways, the dual-targeted approach holds promise in significantly improving outcomes for AMD patients, heralding a new horizon in AMD management and treatment.

Functions of TRPs in retinal tissue in physiological and pathological conditions

The Transient Receptor Potential (TRP) constitutes a family of channels subdivided into seven subfamilies: Ankyrin (TRPA), Canonical (TRPC), Melastatin (TRPM), Mucolipin (TRPML), no-mechano-potential C (TRPN), Polycystic (TRPP), and Vanilloid (TRPV). Although they are structurally similar to one another, the peculiarities of each subfamily are key to the response to stimuli and the signaling pathway that each one triggers. TRPs are non-selective cation channels, most of which are permeable to Ca2+, which is a well-established second messenger that modulates several intracellular signaling pathways and is involved in physiological and pathological conditions in various cell types. TRPs depolarize excitable cells by increasing the influx of Ca2+, Na+, and other cations. Most TRP families are activated by temperature variations, membrane stretching, or chemical agents and, therefore, are defined as polymodal channels. All TPRs are expressed, at some level, in the central nervous system (CNS) and ocular-related structures, such as the retina and optic nerve (ON), except the TRPP in the ON. TRPC, TRPM, TRPV, and TRPML are found in the retinal pigmented cells, whereas only TRPA1 and TRPM are detected in the uvea. Accordingly, several studies have focused on the search to unravel the role of TRPs in physiological and pathological conditions related to the eyes. Thus, this review aims to shed light on endogenous and exogenous modulators, triggered cell signaling pathways, and localization and roles of each subfamily of TRP channels in physiological and pathological conditions in the retina, optic nerve, and retinal pigmented epithelium of vertebrates.

Fundus Image Deep Learning Study to Explore the Association of Retinal Morphology with Age-Related Macular Degeneration Polygenic Risk Score

BACKGROUND

Age-related macular degeneration (AMD) is a complex eye disorder with an environmental and genetic origin, affecting millions worldwide. The study aims to explore the association between retinal morphology and the polygenic risk score (PRS) for AMD using fundus images and deep learning techniques.

METHODS

The study used and pre-processed 23,654 fundus images from 332 subjects (235 patients with AMD and 97 controls), ultimately selecting 558 high-quality images for analysis. The fine-tuned DenseNet121 deep learning model was employed to estimate PRS from single fundus images. After training, deep features were extracted, fused, and used in machine learning regression models to estimate PRS for each subject. The Grad-CAM technique was applied to examine the relationship between areas of increased model activity and the retina's morphological features specific to AMD.

RESULTS

Using the hybrid approach improved the results obtained by DenseNet121 in 5-fold cross-validation. The final evaluation metrics for all predictions from the best model from each fold are MAE = 0.74, MSE = 0.85, RMSE = 0.92, R2 = 0.18, MAPE = 2.41. Grad-CAM heatmap evaluation showed that the model decisions rely on lesion area, focusing mostly on the presence of drusen. The proposed approach was also shown to be sensitive to artifacts present in the image.

CONCLUSIONS

The findings indicate an association between fundus images and AMD PRS, suggesting that deep learning models may effectively estimate genetic risk for AMD from retinal images, potentially aiding in early detection and personalized treatment strategies.

Color Doppler Imaging, Endothelin-1, Corneal Biomechanics and Scleral Rigidity in Asymmetric Age-Related Macular Degeneration

Purpose

Age-related macular degeneration (AMD) presents a multifaceted etiopathogenesis involving ischemic, inflammatory, and genetic components. This study investigates the correlation between ocular hemodynamics, scleral rigidity (SR), and plasma endothelin-1 (ET1) levels in treatment-naive patients with asymmetrical AMD.

Patients and Methods

This study included 20 treatment-naive patients (12 females and 8 males) with an average age of 76.4 ± 3.7 years, who presented with AMD with neovascular membrane formation (nAMD) in one eye, and intermediate grade 2 AMD (iAMD) in the other eye. The control group consisted of 20 healthy subjects (13 females and 7 males) with a mean age of 74.7 ± 3.9 years. All patients and healthy controls underwent color Doppler imaging (i) of the ophthalmic artery (OA), short posterior ciliary arteries (SPCAs), and central retinal artery (CRA); Plasma ET-1 levels were measured for all patients and healthy subjects. Corneal biomechanics were assessed using an Ocular Response Analyzer and two indices were obtained: corneal hysteresis (CH) and corneal resistance factor (CRF).

Results

Results showed reduced blood flow velocities and increased resistance indices in AMD eyes, particularly affecting the short posterior ciliary arteries. According to mechanical theory, ARMD eyes exhibited elevated scleral rigidity and corneal resistance factor compared to controls, with a notable rise in SR in neovascular AMD (nAMD) eyes. As per the chronic subacute inflammation theory, plasma ET-1 levels were significantly higher in AMD patients, correlating with abnormal SPCAs blood flow and increased resistance indices.

Conclusion

Findings suggest a multifactorial etiology of AMD involving an increase of ET-1 plasma levels with biomechanic damages of corneal and scleral tissue in nAMD.

Current developments of gene therapy in human diseases

Gene therapy has witnessed substantial advancements in recent years, becoming a constructive tactic for treating various human diseases. This review presents a comprehensive overview of these developments, with a focus on their diverse applications in different disease contexts. It explores the evolution of gene delivery systems, encompassing viral (like adeno-associated virus; AAV) and nonviral approaches, and evaluates their inherent strengths and limitations. Moreover, the review delves into the progress made in targeting specific tissues and cell types, spanning the eye, liver, muscles, and central nervous system, among others, using these gene technologies. This targeted approach is crucial in addressing a broad spectrum of genetic disorders, such as inherited lysosomal storage diseases, neurodegenerative disorders, and cardiovascular diseases. Recent clinical trials and successful outcomes in gene therapy, particularly those involving AAV and the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated proteins, are highlighted, illuminating the transformative potentials of this approach in disease treatment. The review summarizes the current status of gene therapy, its prospects, and its capacity to significantly ameliorate patient outcomes and quality of life. By offering comprehensive analysis, this review provides invaluable insights for researchers, clinicians, and stakeholders, enriching the ongoing discourse on the trajectory of disease treatment.

Contributions of Lipid-Related Metabolites and Complement Proteins to Early and Intermediate Age-Related Macular Degeneration

Objective

Our objective was to determine the effects of lipids and complement proteins on early and intermediate age-related macular degeneration (AMD) stages using machine learning models by integrating metabolomics and proteomic data.

Design

Nested case-control study.

Subjects and Controls

The analyses were performed in a subset of the Singapore Indian Chinese Cohort (SICC) Eye Study. Among the 6753 participants, we randomly selected 155 Indian and 155 Chinese cases of AMD and matched them with 310 controls on age, sex, and ethnicity.

Methods

We measured 35 complement proteins and 56 lipids using mass spectrometry and nuclear magnetic resonance, respectively. We first selected the most contributing lipids and complement proteins to early and intermediate AMD using random forest models. Then, we estimated their effects using a multinomial model adjusted for potential confounders.

Main Outcome Measures

Age-related macular degeneration was classified using the Beckman classification system.

Results

Among the 310 individuals with AMD, 166 (53.5%) had early AMD, and 144 (46.5%) had intermediate AMD. First, high-density lipoprotein (HDL) particle diameter was positively associated with both early and intermediate AMD (odds ratio [OR]early = 1.69; 95% confidence interval [CI],1.11-2.55 and ORintermediate = 1.72; 95% CI, 1.11-2.66 per 1-standard deviation increase in HDL diameter). Second, complement protein 2 (C2), complement C1 inhibitor (IC1), complement protein 6 (C6), complement protein 1QC (C1QC) and complement factor H-related protein 1 (FHR1), were associated with AMD. C2 was positively associated with both early and intermediate AMD (ORearly = 1.58; 95% CI, 1.08-2.30 and ORintermediate = 1.56; 95% CI, 1.04-2.34). C6 was positively (ORearly = 1.41; 95% CI, 1.03-1.93) associated with early AMD. However, IC1 was negatively associated with early AMD (ORearly = 0.62; 95% CI, 0.38-0.99), whereas C1QC (ORintermediate = 0.63; 95% CI, 0.42-0.93) and FHR1 (ORintermediate = 0.73; 95% CI, 0.54-0.98) were both negatively associated with intermediate AMD.

Conclusions

Although both HDL diameter and C2 levels show associations with both early and intermediate AMD, dysregulations of IC1, C6, C1QC, and FHR1 are only observed at specific stages of AMD. These findings underscore the complexity of complement system dysregulation in AMD, which appears to vary depending on the disease severity.

Financial Disclosures

The authors have no proprietary or commercial interest in any materials discussed in this article.

Decreased Circulating Very Small Low-Density Lipoprotein is Likely Causal for Age-Related Macular Degeneration

Objective

Abnormal changes in metabolite levels in serum or plasma have been highlighted in several studies in age-related macular degeneration (AMD), the leading cause of irreversible vision loss. Specific changes in lipid profiles are associated with an increased risk of AMD. Metabolites could thus be used to investigate AMD disease mechanisms or incorporated into AMD risk prediction models. However, whether particular metabolites causally affect the disease has yet to be established.

Design

A 3-tiered analysis of blood metabolites in the United Kingdom (UK) Biobank cohort to identify metabolites that differ in AMD patients with evidence for a putatively causal role in AMD.

Participants

A total of 72 376 donors from the UK Biobank cohort including participants with AMD (N = 1353) and non-AMD controls (N = 71 023).

Methods

We analyzed 325 directly measured or derived blood metabolites from the UK Biobank for 72 376 donors to identify AMD-associated metabolites. Genome-wide association studies for 325 metabolites in 98 316 European participants from the UK Biobank were performed. The causal effects of these metabolites in AMD were tested using a 2-sample Mendelian randomization approach. The predictive value of these measurements together with sex and age was assessed by developing a machine learning classifier.

Main Outcome Measures

Evaluating metabolic biomarkers associated with AMD susceptibility and investigating their potential causal contribution to the development of the disease.

Results

This study noted age to be the prominent risk factor associated with AMD development. While accounting for age and sex, we identified 84 metabolic markers as significantly (false discovery rate-adjusted P value < 0.05) associated with AMD. Lipoprotein subclasses comprised the majority of the AMD-associated metabolites (39%) followed by several lipoprotein to lipid ratios. Nineteen metabolites showed a likely causative role in AMD etiology. Of these, 6 lipoproteins contain very small, very low-density lipoprotein (VLDL), and phospholipids to total lipid ratio in medium VLDL. Based on this we postulate that depletion of circulating very small VLDLs is likely causal for AMD. The risk prediction model constructed from the metabolites, age and sex, identified age as the primary predictive factor with a much smaller contribution by metabolites to AMD risk prediction.

Conclusions

This study underscores the pronounced role of lipids in AMD susceptibility and the likely causal contribution of particular subclasses of lipoproteins to AMD. Our study provides valuable insights into the metabopathological mechanisms of AMD disease development and progression.

Genetics in neovascular age-related macular degeneration susceptibility and treatment response to anti-VEGF intravitreal injection: A case series study

BACKGROUND

To identify genotypes associated with neovascular age-related macular degeneration (nAMD) and investigate the associations between genotype variations and anti-vascular endothelial growth factor (VEGF) treatment response.

METHODS

This observational, retrospective, case series study enrolled patients diagnosed with nAMD who received anti-VEGF treatment in National Taiwan University Hospital with at least one-year follow-up between 2012 and 2020. A genome-wide association study (GWAS) was conducted on enrolled patients and controls. Correlations between the genotypes identified from GWAS and the treatment response of functional/anatomical biomarkers, including visual acuity (VA), presence of intraretinal or subretinal fluid (SRF), serous or fibrovascular pigmented epithelium detachment (PED), and disruption of the ellipsoid zone (EZ), were analysed.

RESULTS

In total, 182 patients with nAMD and 1748 controls were enrolled. GWAS revealed 16 single nucleotide polymorphisms (SNPs) as risk loci for nAMD, including seven loci in CFH and ARMS2/HTRA1 and nine novel loci, including rs117517872 and rs79835234(COPB2-DT), rs7525578(RAP1A), rs2123738(LOC105376755), rs1374879(CNTN3), rs3812692(SAR1A), rs117501587(PRKCA), rs9965945(CNDP1), and rs189769231(MATK). Our study revealed rs800292(CFH), rs11200638(HTRA1), and rs2123738(LOC105376755) correlated with poor treatment response in VA (P = 0.005), SRF (P = 0.044), and fibrovascular PED (P = 0.007), respectively. Rs9965945(CNDP1) was correlated with poor response in disruption of EZ (P = 0.046) and serous PED (P = 0.049).

CONCLUSIONS

Among the 16 SNPs found in the GWAS, four loci-CFH, ARMS2/HTRA1, and two novel loci-were correlated with the susceptibility of nAMD and anatomical/functional responses after anti-VEGF treatment.

Genetic Insights into Age-Related Macular Degeneration

One of the major causes of vision impairment among elderly people in developed nations is age-related macular degeneration (AMD). The distinctive features of AMD are the accumulation of extracellular deposits called drusen and the gradual deterioration of photoreceptors and nearby tissues in the macula. AMD is a complex and multifaceted disease influenced by several factors such as aging, environmental risk factors, and a person's genetic susceptibility to the condition. The interaction among these factors leads to the initiation and advancement of AMD, where genetic predisposition plays a crucial role. With the advent of high-throughput genotyping technologies, many novel genetic loci associated with AMD have been identified, enhancing our knowledge of its genetic architecture. The common genetic variants linked to AMD are found on chromosome 1q32 (in the complement factor H gene) and 10q26 (age-related maculopathy susceptibility 2 and high-temperature requirement A serine peptidase 1 genes) loci, along with several other risk variants. This review summarizes the common genetic variants of complement pathways, lipid metabolism, and extracellular matrix proteins associated with AMD risk, highlighting the intricate pathways contributing to AMD pathogenesis. Knowledge of the genetic underpinnings of AMD will allow for the future development of personalized diagnostics and targeted therapeutic interventions, paving the way for more effective management of AMD and improved outcomes for affected individuals.

Drug Approval for the Treatment of Geographic Atrophy: How We Got Here and Where We Need to Go

PURPOSE

To discuss the clinical trial results leading to the US Food and Drug Administration (FDA) approval of anti-complement therapies for geographic atrophy (GA), perspectives on functional data from the GA clinical trials, and how lessons from the FDA approval may guide future directions for basic and clinical research in AMD.

DESIGN

Selected literature review with analysis and perspective METHODS: We performed a targeted review of publicly available data from the clinical trials of pegcetacoplan and avacincaptad for the treatment of GA, as well as scientific literature on the natural history of GA and the genetics and basic science of complement in AMD.

RESULTS

The approval of pegcetacoplan and avacincaptad was based on an anatomic endpoint of a reduction in the rate of GA expansion over time. However, functional data from 2 phase 3 clinical trials for each drug demonstrated no visual benefit to patients in the treatment groups. Review of the genetics of AMD and the basic science of the role for complement in AMD provides only modest support for targeting complement as treatment for GA expansion, and alternative molecular targets for GA treatment are therefore discussed. Reasons for the disconnect between anatomic and functional outcomes in the clinical trials of anti-complement therapies are discussed, providing insight to guide the configuration of future clinical studies for GA.

CONCLUSION

Although avacincaptad and pegcetacoplan are our first FDA-approved treatments for GA, results from the clinical trials failed to show any functional improvement after 1 and 2 years, respectively, calling into question whether the drugs represent a "clinically relevant outcome." To improve the chances of more impactful therapies in the future, we provide basic-science rationale for pursuing non-complement targets; emphasize the importance of ongoing clinical research that more closely pins anatomic features of GA to functional outcomes; and provide suggestions for clinical endpoints for future clinical trials on GA.

Association between dietary consumption of fatty acids and age-related macular degeneration in the National Health and Nutrition Examination Survey

The aim of this study is to assess the relationship between dietary intake of fatty acids and the age-related macular degeneration (AMD) in the United States population. Adult participants of the 2005-2008 National Health and Nutrition Examination Survey (NHANES) were included in this nationwide cross-sectional study. Dietary fatty acid intake was obtained from two 24-h dietary recall interviews. The intake of dietary fatty acids was analyzed as a continuous and categorical variable. AMD status was assessed using nonmydriatic fundus photographs. Univariate and multivariate logistic regression analyses were used to assess the association between dietary fatty acid intake and AMD. The unweighted population included 4702 individuals of whom 374 had AMD. After adjusting for relevant variables, each 1 unit increase (1 mg/1000 kcal) intake of EPA (OR: 0.996, 95% CI: 0.993-0.996, P = 0.018), DPA (OR: 0.976, 95% CI: 0.962-0.990, P = 0.002), and DHA (OR: 0.996, 95% CI: 0.994-0.999, P = 0.003) were significantly decreased odds of any AMD. The highest versus lowest quartile of EPA (OR: 0.476, P for trend < 0.001), DPA (OR: 0.467, P for trend = 0.005) and DHA (OR: 0.586, P for trend = 0.008) were negatively associated with the odds of any AMD. Subgroup analysis showed that higher quartiles of EPA (OR: 0.461, P for trend < 0.002), DPA (OR: 0.467, P for trend = 0.006) and DHA (OR: 0.578, P for trend = 0.007) exhibited a negative association with early AMD. The study found no significant association between the intake of dietary fatty acids, including n-3 PUFA, and the odds of late AMD. In the 2005-2008 NHANES population, higher dietary DHA, DPA and EPA intake associated with decreased odds of early AMD. However, no clear association was found between specific types of FAs and late AMD.

Age-Related Macular Degeneration and Extramacular Drusen: Genetic Associations in the Coimbra Eye Study

Purpose

To explore the association between the genetics of age-related macular degeneration (AMD) and extramacular drusen (EMD) in patients with and without AMD.

Methods

We included 1753 eyes (912 subjects) with phenotypic characterization regarding AMD and EMD. Genetic sequencing and the genetic risk score (GRS) for AMD were performed according to the EYE-RISK consortium methodology. To test for differences in the GRS from EMD cases, AMD cases, and controls, a clustered Wilcoxon rank-sum test was used. The association of AMD, EMD, and the GRS was evaluated using logistic regression models adjusted for age and sex. Individual associations of common risk variants for AMD with EMD were explored.

Results

EMD were found in 755 eyes: 252 (14.4%) with AMD and 503 (28.7%) without. In total, 122 eyes (7.0%) had only AMD, and 876 (50.0%) were controls. EMD were strongly associated with AMD (odds ratio [OR], 3.333; 95% confidence interval [CI], 2.356-4.623; P < 0.001). The GRS was associated with an increased risk of AMD (OR, 1.416; 95% CI, 1.218-1.646; P < 0.001) but not with EMD. Individually, the common risk variants ARMS2 rs10490924 (P = 0.042), C3 rs2230199 (P = 0.042), and CETP rs5817082 (P = 0.042) were associated with EMD, after adjustment for AMD, sex, and age.

Conclusions

We found a strong association between EMD and AMD, suggesting a common pathogenesis. The GRS for AMD was not associated with EMD, but a partially overlapping genetic basis was suggested when assessing individual risk variants. We propose that EMD per se do not represent an increase in the global genetic risk for AMD.

Translocator protein (18 kDa) (Tspo) in the retina and implications for ocular diseases

Translocator protein (18 kDa) (Tspo), formerly known as peripheral benzodiazepine receptor is a highly conserved transmembrane protein primarily located in the outer mitochondrial membrane. In the central nervous system (CNS), especially in glia cells, Tspo is upregulated upon inflammation. Consequently, Tspo was used as a tool for diagnostic in vivo imaging of neuroinflammation in the brain and as a potential therapeutic target. Several synthetic Tspo ligands have been explored as immunomodulatory and neuroprotective therapy approaches. Although the function of Tspo and how its ligands exert these beneficial effects is not fully clear, it became a research topic of interest, especially in ocular diseases in the past few years. This review summarizes state-of-the-art knowledge of Tspo expression and its proposed functions in different cells of the retina including microglia, retinal pigment epithelium and Müller cells. Tspo is involved in cytokine signaling, oxidative stress and reactive oxygen species production, calcium signaling, neurosteroid synthesis, energy metabolism, and cholesterol efflux. We also highlight recent developments in preclinical models targeting Tspo and summarize the relevance of Tspo biology for ocular and retinal diseases. We conclude that glial upregulation of Tspo in different ocular pathologies and the use of Tspo ligands as promising therapeutic approaches in preclinical studies underline the importance of Tspo as a potential disease-modifying protein.

Potential Causal Association between C-Reactive Protein Levels in Age-Related Macular Degeneration: A Two-Sample Mendelian Randomization Study

Researchers have proposed a possible correlation between age-related macular degeneration (AMD) and inflammation or C-reactive protein (CRP) levels. We investigated the potential causal relationship between CRP levels and AMD. Single-nucleotide polymorphisms (SNPs) associated with CRP exposure were selected as the instrumental variables (IVs) with significance (p < 5 × 10-8) from the genome-wide association study (GWAS) meta-analysis data of Biobank Japan and the UK Biobank. GWAS data for AMD were obtained from 11 International AMD Genomics Consortium studies. An evaluation of causal estimates, utilizing the inverse-variance-weighted (IVW), weighted-median, MR-Egger, MR-Pleiotropy-Residual-Sum, and Outlier tests, was conducted in a two-sample Mendelian randomization (MR) study. We observed significant causal associations between CRP levels and AMD (odds ratio [OR] = 1.13, 95% CI = [1.02-1.24], and p = 0.014 in IVW; OR = 1.18, 95% CI = [1.00-1.38], and p = 0.044 in weight median; OR = 1.31, 95% CI = [1.13-1.52], and p < 0.001 in MR-Egger). The causal relationship between CRP and AMD warrants further research to address the significance of inflammation as a risk factor for AMD.

Levels of the HtrA1 Protein in Serum and Vitreous Humor Are Independent of Genetic Risk for Age-Related Macular Degeneration at the 10q26 Locus

Purpose

The purpose of this study was to determine if levels of the HtrA1 protein in serum or vitreous humor are influenced by genetic risk for age-related macular degeneration (AMD) at the 10q26 locus, age, sex, AMD status, and/or AMD disease severity, and, therefore, to determine the contribution of systemic and ocular HtrA1 to the AMD disease process.

Methods

A custom-made sandwich ELISA assay (SCTM ELISA) for detection of the HtrA1 protein was designed and compared with three commercial assays (R&D Systems, MyBiosource 1 and MyBiosource 2) using 65 serum samples. Concentrations of HtrA1 were thereafter determined in serum and vitreous samples collected from 248 individuals and 145 human donor eyes, respectively.

Results

The SCTM ELISA demonstrated high specificity, good recovery, and parallelism within its linear detection range and performed comparably to the R&D Systems assay. In contrast, we were unable to demonstrate the specificity of the two assays from MyBioSource using either recombinant or native HtrA1. Analyses of concentrations obtained using the validated SCTM assay revealed that genetic risk at the 10q26 locus, age, sex, or AMD status are not significantly associated with altered levels of the HtrA1 protein in serum or in vitreous humor (P > 0.05).

Conclusions

HtrA1 levels in serum and vitreous do not reflect the risk for AMD associated with the 10q26 locus or disease status. Localized alteration in HTRA1 expression in the retinal pigment epithelium, rather than systemic changes in HtrA1, is the most likely driver of elevated risk for developing AMD among individuals with risk variants at the 10q26 locus.

Evidence for Genetic Causal Relationships Between Multiple Immune-Mediated Inflammatory Diseases and Age-Related Macular Degeneration: A Univariable and Multivariable Mendelian Randomization Study

INTRODUCTION

With the global aging population on the rise, age-related macular degeneration (AMD) poses a growing healthcare burden. Prior research hints at immune-mediated inflammatory diseases (IMIDs) potentially elevating AMD risk via diverse mechanisms. However, causality remains disputed as a result of confounding factors. Hence, our Mendelian randomization (MR) study aims to untangle this link, mitigating confounding effects to explore the IMID-AMD causal relationship. This study aims to investigate the causal relationship between IMIDs and AMD, providing new strategies for the prevention and treatment of AMD in clinical practice.

METHODS

This study was registered with PROSPERO, CRD42023469815. We obtained data on IMIDs and AMD from Genome-Wide Association Studies (GWAS) summary statistics and the FinnGen consortium. Rigorous selection steps were applied to screen for eligible instrumental single nucleotide polymorphisms (SNPs). We conducted univariate Mendelian randomization, inverse variance-weighted (IVW), weighted median, Mendelian randomization-Egger (MR-Egger), and multivariate Mendelian randomization (MVMR) analyses. Various sensitivity analysis methods were employed to assess pleiotropy and heterogeneity. The aim was to explore the causal relationships between IMIDs and AMD.

RESULTS

The MR analysis revealed that Crohn's disease (CD) (IVW: odd ratios (OR) 1.05, 95% CI (confidence interval) 1.01-1.10, p = 0.007), rheumatoid arthritis (RA) (IVW: OR 1.09, 95% CI 1.04-1.15, p = 0.0001), and type 1 diabetes (T1D) (IVW: OR 1.05, 95% CI 1.02-1.09, p = 0.001) were correlated with an elevated risk of AMD, while multiple sclerosis (MS) (IVW: OR 2.78E-18, 95% CI 2.23E-31 to 3.48E-05, p = 0.008) appeared to be protective against AMD. These findings were supported by an array of MR analysis methodologies and the MVMR approach.

CONCLUSION

Our study results, based on MR, provide genetic evidence indicating a causal relationship between specific IMIDs and AMD. CD, RA, and T1D are factors increasing the risk of AMD, while MS may have a protective effect.

Causal Associations of Glaucoma and Age-Related Macular Degeneration with Cataract: A Bidirectional Two-Sample Mendelian Randomisation Study

Common age-related eye disorders include glaucoma, cataract, and age-related macular degeneration (AMD); however, little is known about their relationship with age. This study investigated the potential causal relationship between glaucoma and AMD with cataract using genetic data from multi-ethnic populations. Single-nucleotide polymorphisms (SNPs) associated with exposure to cataract were selected as instrumental variables (IVs) from genome-wide association studies using meta-analysis data from BioBank Japan and UK Biobank. A bidirectional two-sample Mendelian randomisation (MR) study was conducted to assess the causal estimates using inverse variance weighted, MR-Egger, and MR pleiotropy residual sum and outlier tests. SNPs with (p < 5.0 × 10-8) were selected as IVs for cataract, primary open-angle glaucoma, and AMD. We found no causal effects of cataract on glaucoma or AMD (all p > 0.05). Furthermore, there were no causal effects of AMD on cataract (odds ratio [OR] = 1.02, p = 0.400). However, glaucoma had a substantial causal effect on cataract (OR = 1.14, p = 0.020). Our study found no evidence for a causal relationship of cataract on glaucoma or AMD and a casual effect of AMD on cataract. Nonetheless, glaucoma demonstrates a causal link with cataract formation, indicating the need for future investigations of age-related eye diseases.

QTL mapping of human retina DNA methylation identifies 87 gene-epigenome interactions in age-related macular degeneration

DNA methylation provides a crucial epigenetic mark linking genetic variations to environmental influence. We have analyzed array-based DNA methylation profiles of 160 human retinas with co-measured RNA-seq and >8 million genetic variants, uncovering sites of genetic regulation in cis (37,453 methylation quantitative trait loci and 12,505 expression quantitative trait loci) and 13,747 DNA methylation loci affecting gene expression, with over one-third specific to the retina. Methylation and expression quantitative trait loci show non-random distribution and enrichment of biological processes related to synapse, mitochondria, and catabolism. Summary data-based Mendelian randomization and colocalization analyses identify 87 target genes where methylation and gene-expression changes likely mediate the genotype effect on age-related macular degeneration. Integrated pathway analysis reveals epigenetic regulation of immune response and metabolism including the glutathione pathway and glycolysis. Our study thus defines key roles of genetic variations driving methylation changes, prioritizes epigenetic control of gene expression, and suggests frameworks for regulation of macular degeneration pathology by genotype-environment interaction in retina.