The complement system in age-related macular degeneration

The gut-eye axis: from brain neurodegenerative diseases to age-related macular degeneration

Age-related macular degeneration is a serious neurodegenerative disease of the retina that significantly impacts vision. Unfortunately, the specific pathogenesis remains unclear, and effective early treatment options are consequently lacking. The microbiome is defined as a large ecosystem of microorganisms living within and coexisting with a host. The intestinal microbiome undergoes dynamic changes owing to age, diet, genetics, and other factors. Such dysregulation of the intestinal flora can disrupt the microecological balance, resulting in immunological and metabolic dysfunction in the host, and affecting the development of many diseases. In recent decades, significant evidence has indicated that the intestinal flora also influences systems outside of the digestive tract, including the brain. Indeed, several studies have demonstrated the critical role of the gut-brain axis in the development of brain neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease. Similarly, the role of the "gut-eye axis" has been confirmed to play a role in the pathogenesis of many ocular disorders. Moreover, age-related macular degeneration and many brain neurodegenerative diseases have been shown to share several risk factors and to exhibit comparable etiologies. As such, the intestinal flora may play an important role in age-related macular degeneration. Given the above context, the present review aims to clarify the gut-brain and gut-eye connections, assess the effect of intestinal flora and metabolites on age-related macular degeneration, and identify potential diagnostic markers and therapeutic strategies. Currently, direct research on the role of intestinal flora in age-related macular degeneration is still relatively limited, while studies focusing solely on intestinal flora are insufficient to fully elucidate its functional role in age-related macular degeneration. Organ-on-a-chip technology has shown promise in clarifying the gut-eye interactions, while integrating analysis of the intestinal flora with research on metabolites through metabolomics and other techniques is crucial for understanding their potential mechanisms.

Autoantibodies and therapeutic antibodies against complement factor H

The complement system is a crucial part of our immune defense as, upon recognition, it can kill pathogens fast and effectively. However, misguided complement activation could cause damage to host tissues. Therefore, a well-controlled regulation of the complement system is a necessity to prevent collateral damage. Regulation is achieved by several complement inhibitory proteins, acting at different levels of the complement system. One of these complement regulators is factor H, the main regulator of the alternative complement activation pathway. Factor H can regulate the complement system both in fluid-phase and on the host cell surface by, for example, acting as co-factor for factor I, inactivating C3b. The functional properties of factor H are located within different regions of the protein. Functional impairment of factor H, either because of genetic variants, competing proteins such as the factor H-related proteins and proteins from certain pathogens, but also the presence of autoantibodies will impact on complement activation. However, exact consequences are dependent on the region within factor H that is affected. Autoantibodies binding to factor H have been shown to inhibit several regulatory functions of factor H, which is observed in diseases such as membranoproliferative glomerulonephritis and atypical hemolytic uremic syndrome. As more recently the presence of anti-factor H autoantibodies has also been discovered in several other diseases, ranging from autoimmune diseases to cancer, this review provides an overview of the presence of factor H autoantibodies described in these diseases. Factor H autoantibodies are reported to have inhibitory, or enhancing, effects on factor H, depending on the epitopes that are recognized. Formal conclusions about the pathogenicity of the factor H autoantibodies in some of these diseases cannot be drawn yet. Importantly, understanding the binding and functional impact of anti-factor H (auto)antibodies will allow targeted interventions to diminish pathological consequences of anti-factor H autoantibodies but may also open up additional avenues for the use of anti-factor H antibodies as therapeutic agents.

Dysregulated lipid metabolism in a retinal pigment epithelial cell model and serum of patients with age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is a leading cause of blindness, characterized by retinal pigment epithelium (RPE) dysfunction, extracellular deposit formation, and disrupted lipid metabolism. Understanding the molecular changes underlying AMD is essential for identifying diagnostic markers and therapeutic targets.

RESULTS

This multiomic study employed a primary RPE culture model to investigate age-related changes associated with AMD. Over 25 weeks, RPE cells exhibited phenotypic deterioration, including depigmentation, cell shape deformation, and barrier integrity loss, accompanied by extracellular deposit formation. Transcriptomic analysis revealed dysregulation of genes involved in lipid metabolism, including pathways for cholesterol transport, glycerophospholipids, and ceramide biosynthesis. Metabolomic profiling further identified significant changes in glycerophospholipid and sphingolipid metabolism, highlighting a decline in phospholipid species and ceramide accumulation. Serum analysis of AMD patients revealed altered levels of 18 lipids identified in RPE cultures. Four lipids showed significant differences compared to controls: GlcCer(d16:1/18:0) (1.23-fold increase, adj. p value < 0.001), PE(19:1(9Z)/22:2(13Z,16Z)) (0.34-fold decrease, adj. p value < 0.001), PE(15:0/20:3(5Z,8Z,11Z)) (0.66-fold decrease, adj. p value < 0.05), and PC(22:2(13Z,16Z)/13:0) (0.71-fold decrease, adj. p value < 0.05). These findings underscore the systemic nature of lipid dysregulation in AMD and the translational relevance of the RPE model.

CONCLUSIONS

This study highlights the significant role of lipid metabolism dysregulation in AMD pathogenesis. The consistent lipidomic alterations observed in RPE cultures and AMD patient serum reinforce their potential as biomarkers for disease progression and therapeutic targets. These findings provide a robust framework for understanding AMD-associated lipid metabolism changes and their systemic impact.

Plasma extracellular vesicles carry immune system-related peptides that predict human longevity

Extracellular vesicles (EVs) play crucial roles in aging. In this National Institutes on Aging-funded study, we sought to identify circulating extracellular vesicle (EV) biomarkers indicative of longevity. The plasma EV proteome of 48 older adults (mean age 77.2 ± 1.7 years [range 72-80]; 50% female, 50% Black, 50% < 2-year survival, 50% ≥ 10-year survival) was analyzed by high-resolution mass spectrometry and flow cytometry. The ability of EV peptides to predict longevity was evaluated in discovery (n = 32) and validation (n = 16) datasets with areas under receiver operating characteristic curves (AUCs). Longevity-associated large EV (LEV) plasma subpopulations were mainly related to immune cells (HLA-ABC+, CD9+, and CD31+) and muscle cells (MCAD+ and RyR2+). Of 7960 identified plasma EV peptides (519 proteins), 46.4% were related to the immune system and 10.1% to muscle. Compared with short-lived older adults, 756 EV peptides (131 proteins) had a higher abundance, and 130 EV peptides (78 proteins) had a lower abundance in long-lived adults. Among longevity-associated peptides, 437 (58 proteins) were immune system related, and 12 (2 proteins) were muscle related. Using just three to five plasma EV peptides (mainly complement components C2-C6), we achieved high predictive accuracy for longevity (AUC range 0.91-1 in a hold-out validation dataset). Our findings suggest that immune cells produce longevity-associated plasma EVs and elucidate fundamental mechanisms regulating aging and longevity. EV longevity predictors suggest there may be merit in targeting complement pathways to extend lifespan, for instance, with any one of the multiple complement inhibitors currently available or in clinical development.

Roles of MASP-1 and MASP-3 in the development of retinal degeneration in a murine model of dry age-related macular degeneration

Complement is activated through the three different pathways, which are the classical (CP), lectin (LP), and alternative pathways (AP). Complement activation functions to eliminate invading pathogens, whereas dysregulation of complement activation can induce inflammatory disorders such as age-related macular degeneration (AMD). In retinal degeneration induced by sodium iodate (NaIO3), a murine model of dry AMD (also called atrophic AMD), it has been suggested that the AP and CP are involved in the disease development. On the other hand, the role of the LP in the development of AMD remains unclear. In the current study, we generated murine dry AMD model with NaIO3 using mice deficient for mannose-binding lectin-associated serine protease (MASP)-1 and/or MASP-3, which are required for the LP and AP activation, respectively. Wild-type (WT) C57BL/6J mice showed retinal degeneration, including depigmentation and disruption of the retinal pigment epithelium (RPE), atrophy of the photoreceptor layer (PL), and thinning of the outer nuclear layer (ONL) after NaIO3 injection. In contrast, those pathological changes after NaIO3 injection were significantly attenuated in MASP-1-deficient (MASP-1-/-), MASP-3-deficient (MASP-3-/-), and MASP-1/3-double deficient (MASP-1/3-/-) mice. These results indicate that both MASP-1 and MASP-3 play a role in photoreceptor degeneration in the NaIO3-induced murine dry AMD model. In addition, photoreceptor cell death and retinal C3 activation were observed in NaIO3-injected WT mice, whereas those pathological changes were significantly attenuated in NaIO3-injected MASP-3-/- and MASP-1/3-/- mice. On the other hand, those pathological changes in NaIO3-injected MASP-1-/- mice were comparable to those in NaIO3-injected WT mice. Taken together, our results indicate that MASP-3 plays a pivotal role in C3 activation in the retina most likely via activation of the AP leading to the development of retinal degeneration in the NaIO3-induced murine dry AMD model. Our results also indicate that MASP-1 plays a role in the development of NaIO3-induced retinal degeneration in this murine model, although it remains unclear whether its role in the retinal degeneration is through the LP activation.

Potentiating CD20 monoclonal antibody therapy by targeting complement C3 fragments covalently deposited on lymphoma cells

ABSTRACT

Monoclonal antibodies (mAbs) improve survival of patients with mature B-cell malignancies. Fcγ receptor-dependent effector mechanisms kill tumor cells but can promote antigen loss through trogocytosis, contributing to treatment failures. Cell-bound mAbs trigger the complement cascade to deposit C3 activation fragments and lyse cells. Within 24 hours after ofatumumab administration to patients with chronic lymphocytic leukemia (CLL), circulating tumor cells had lost CD20 and were opsonized with C3d, the terminal covalently bound form of complement protein C3. We hypothesized that C3d provides a target to eliminate residual CD20- tumor cells. To test this hypothesis, we generated C8xi, a mouse/human chimeric immunoglobulin G1 (IgG1) that reacts with human but not mouse C3d. C8xi was effective in a patient-derived xenograft model against CD20-, C3d opsonized CLL cells from patients treated with ofatumumab. We also generated rabbit mAbs, 2 of which were chosen because they bound mouse and human C3d with low nanomolar affinity but were minimally cross-reactive with full-length C3. Anti-C3d rabbit/human chimeric IgG1 in combination with ofatumumab or rituximab prolonged survival of xenografted mice that model 3 different types of non-Hodgkin lymphoma (NHL). For example, in a diffuse large B-cell lymphoma model (SU-DHL-6), median survival with single-agent CD20 mAb was 114 days but was not reached for mAb combination treatment (P = .008). In another NHL model (SU-DHL-4), single-agent and combination mAb therapy eradicated lymphoma in most mice. In long-term survivors from both cohorts, there was no evidence of adverse effects. We propose that C3d mAbs combined with complement-fixing CD20 mAbs can overcome antigen-loss escape and increase efficacy of mAb-based therapy.

Decreased complement 4 and interleukin-10 as biomarkers in aqueous humour for non-exudative age-related macular degeneration: a case control study

BACKGROUND

The development of age-related macular degeneration (AMD) is influenced by risk factors that contribute to inflammatory processes, cellular stress responses, and a dysregulation of the complement system. Given the incomplete understanding of the pathogenesis of AMD and the necessity for novel therapeutics, biomarker studies investigating aqueous humour from the anterior chamber of the eye serve as a valuable tool. This pilot study aimed to assess inflammatory mediators and complement components in aqueous humour of non-exudative AMD patients in comparison with a control group.

METHODS

The aqueous humour of 12 non-exudative AMD patients and 21 control subjects was collected during cataract surgery. Levels of 78 inflammatory proteins and complement components were measured using multiplex immunoassays. The influence of sex or smoking on the AMD status was assessed using Pearson's chi-square test. Biomarker levels between AMD patients vs. controls, smokers vs. non-smokers, and females vs. males were compared. Parametric datasets were analysed using independent-means t-test, while non-parametric data analysis was conducted utilising Wilcoxon's rank-sum test. Spearman's correlation investigated associations between drusen volume and biomarker levels, as well as biomarker levels and subject age.

RESULTS

All examined 78 immunological factors were detectable in aqueous humour. The proteins were categorised into high, medium, and low level groups. Aqueous humour contained high levels of complement proteins, including iC3b, FH/FHL-1, C4B, and FI. Non-exudative AMD patients exhibited decreased levels of C4 (P = 0.020), IL-10 (P = 0.033), and FI (P = 0.082). A positive correlation was observed between drusen volume and CCL4 levels (rS = 0.78, P = 0.013). Furthermore, smokers demonstrated significantly increased levels of pro-inflammatory proteins (CCL7, IL-7; P = 0.027, P = 0.030). MMP-1 was positively correlated with age (rS = 0.44, P = 0.010), while sex differences were observed in FB (P = 0.027) and C4B (P = 0.036) levels.

CONCLUSIONS

This pilot study presents an initial overview of inflammation-associated biomarkers in the aqueous humour, highlighting potential roles for C4 and IL-10 in the development of non-exudative AMD. A larger, more-focused follow-up study is in progress to further investigate biomarkers localised to the eye and refine our understanding of AMD.

Porcine Sub-Retinal Pigment Epithelium Deposits: A Model for Dry Age-Related Macular Degeneration With Comparison to Human Drusen

Purpose

Due to the slowly progressing nature of age-related macular degeneration (AMD) and critical differences in ocular anatomy between humans and animals, it has been difficult to model disease progression, hampering the development of novel therapeutics aimed at impacting drusen biogenesis. To determine whether "drusen-in-a-dish" model systems are of utility in screening potential therapeutics aimed at early-intermediate dry AMD, we developed a detailed characterization of the protein, glycoprotein, and lipid composition of sub-retinal pigment epithelium (RPE) deposits grown by monolayers of ex vivo porcine RPE with human drusen in AMD globes.

Methods

Immunohistochemistry and imaging mass spectrometry (IMS) were performed on 20-week aged monolayers of porcine RPE and human donor globes recovered from an 81-year-old non-transplant donor with confirmed diagnosis of bilateral dry AMD. The presence of major protein, glycoprotein, and lipid species was compared between porcine sub-RPE deposits and human drusen with reference to macular/peripheral eccentricity.

Results

The protein and glycoprotein composition of porcine sub-RPE deposits closely mimics human drusen identified in donor globes with dry AMD, including the presence of major complement components (C9, CFH, CHI), apolipoproteins (ApoE, ApoJ), extracellular matrix proteins (vitronectin, collagen VI), and calcification (hydroxyapatite). Sub-RPE deposits were additionally rich in long-chain ceramide species (Cer, CerPE, PI), which have only recently been described in human drusen.

Conclusions

Due to their compositional similarity to human drusen, ex vivo "drusen-in-a-dish" systems represent a potentially robust and cost-effective model for both studying the pathobiology of drusen biogenesis and screening novel therapeutics aimed at limiting drusen formation.

Differential Roles of Macrophages and Microglia in Subretinal Fibrosis Secondary to Neovascular Age-Related Macular Degeneration

Purpose

To investigate the differential role of infiltrating CCR2+ macrophages and CX3CR1+ microglia in neovascular AMD (nAMD)-mediated subretinal fibrosis.

Methods

Subretinal fibrosis was induced using the two-stage laser protocol in C57BL/6J or CX3CR1gfp/+ mice. The fibrotic lesion was detected using collagen-1 staining in retinal pigment epithelial /choroidal flatmounts. Infiltrating macrophages and microglial were identified using F4/80, CCR2, and CX3CR1 markers at one, three, six, and 10 days after the second laser. Circulating CCR2+ monocytes were depleted using the MC-21 antibody, whereas CX3CR1+ microglia were depleted using PLX5622. BV2 microglia were treated with TGF-β1 for 96 hours, and their profibrotic potential was examined by quantitative PCR and immunocytochemistry.

Results

Subretinal fibrosis lesions developed three days after the second laser, accompanied by persistent CCR2+F4/80+ macrophage and CX3CR1+ cell infiltration. Inflammation in the first three days after the second laser was dominated by filtrating CX3CR1+ cells, and the number increased until day (D) 10 post-second laser. Depletion of CCR2+ monocytes from D5-10 significantly reduced the vascular and fibrotic components of the lesion, while CX3CR1+ cell depletion reduced Isolectin B4+ but not collagen-1+ lesion size. Bone marrow-derived macrophages from D6 and D10 mice expressed significantly higher levels of α-smooth muscle actin (α-SMA) and collagen-1 compared to cells from D1 and D3. TGFβ1 treatment increased TMEM119, CX3CR1, IL1b and iNOS gene expression but did not affect Acta2 and Col1a1 gene expression in BV2 cells.

Conclusions

CCR2+ monocytes, but not CX3CR1+ microglia, critically contribute to the development of subretinal fibrosis in nAMD.

2024 White Paper on Recent Issues in Bioanalysis: Three Way-Cross Validation; Urine Clinical Analysis; Automated Methods; Regulatory Queries on Plasma Protein Binding; Automated Biospecimen Management; ELN Migration; Ultra-Sensitivity Mass Spectrometry (Part 1A - Recommendations on Advanced Strategies for Mass Spectrometry Assays, Chromatography, Sample Preparation and BMV/Regulated Bioanalysis Part 1B - Regulatory Agencies' Inputs on Regulated Bioanalysis/BMV)

The 18th Workshop on Recent Issues in Bioanalysis (18th WRIB) took place in San Antonio, TX, USA on May 6-10, 2024. Over 1100 professionals representing pharma/biotech companies, CROs, and multiple regulatory agencies convened to actively discuss the most current topics of interest in bioanalysis. The 18th WRIB included 3 Main Workshops and 7 Specialized Workshops that together spanned 1 week to allow an exhaustive and thorough coverage of all major issues in bioanalysis of biomarkers, immunogenicity, gene therapy, cell therapy and vaccines.Moreover, in-depth workshops on "IVDR Implementation in EU & Changes for LDT in the US" and on "Harmonization of Vaccine Clinical Assays Validation" were the special features of the 18th edition.As in previous years, WRIB continued to gather a wide diversity of international, industry opinion leaders and regulatory authority experts working on both small and large molecules as well as gene, cell therapies and vaccines to facilitate sharing and discussions focused on improving quality, increasing regulatory compliance, and achieving scientific excellence on bioanalytical issues.This 2024 White Paper encompasses recommendations emerging from the extensive discussions held during the workshop and is aimed to provide the bioanalytical community with key information and practical solutions on topics and issues addressed, in an effort to enable advances in scientific excellence, improved quality and better regulatory compliance. Due to its length, the 2024 edition of this comprehensive White Paper has been divided into three parts for editorial reasons.This publication (Part 1) covers in Part 1A the Recommendations on Mass Spectrometry Assays and Regulated Bioanalysis/BMV and in Part 1B the Regulatory Inputs on these topics. Part 3 (Gene Therapy, Cell therapy, Vaccines and Biotherapeutics Immunogenicity) and Part 2 (Biomarkers/BAV, IVD/CDx, LBA and Cell-Based Assays) are published in volume 17 of Bioanalysis, issues 3 and 4 (2025), respectively.

Ovarian Aging: The Silent Catalyst of Age-Related Disorders in Female Body

Age-related diseases have emerged as a global concern as the population ages. Consequently, understanding the underlying causes of aging and exploring potential anti-aging interventions is imperative. In females, the ovaries serve as the principal organs responsible for ovulation and the production of female hormones. The aging ovaries are related to infertility, menopause, and associated menopausal syndromes, with menopause representing the culmination of ovarian aging. Current evidence indicates that ovarian aging may contribute to dysfunction across multiple organ systems, including, but not limited to, cognitive impairment, osteoporosis, and cardiovascular disease. Nevertheless, due to the widespread distribution of sex hormone receptors throughout the body, ovarian aging affects not only these specific organs but also influences a broader spectrum of age-related diseases in women. Despite this, the impact of ovarian aging on overall age-related diseases has been largely neglected. This review provides a thorough summary of the impact of ovarian aging on age-related diseases, encompassing the nervous, circulatory, locomotor, urinary, digestive, respiratory, and endocrine systems. Additionally, we have outlined prospective therapeutic approaches for addressing both ovarian aging and age-related diseases, with the aim of mitigating their impacts and preserving women's fertility, physical health, and psychological well-being.

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.

Metabolomic and transcriptomic analysis reveals metabolic-immune interactions in choroid neovascularization

Choroid neovascularization (CNV) is a distinct type of age-related macular degeneration (AMD) with a poor prognosis and responsible for the majority of vision loss in the elderly population. The laser-induced CNV model is a well-established animal model frequently used to study CNV. In this study, we performed an integrated analysis of metabolomic and transcriptomic data from CNV samples, utilizing multiple approaches including single-sample gene set enrichment analysis (ssGSEA), correlation analysis, and weighted gene co-expression network analysis (WGCNA), alongside various bioinformatics platforms, to identify key metabolic and immune signatures and to investigate their interplay during angiogenesis. Dominant infiltration of macrophages and monocytes was detected and a positive correlation between dysregulated riboflavin metabolism and angiogenesis pathways was characterized. Hub genes such as ectonucleotide pyrophosphatase/phosphodiesterase 1 (Enpp1) and acid phosphatase 5, tartrate resistant (ACP5) emerged as potential central regulators of immune-metabolic crosstalk in CNV. The classification of the immune and metabolic landscape and their critical interactions in CNV models will enhance the understanding of the pathogenesis of neovascular AMD and other neovascular eye diseases, contributing to the development of multi-targeted therapeutic strategies with better efficacy.

Association of dietary inflammatory index with ocular diseases: a population-based cross-sectional study

BACKGROUND

Our research was designed to investigate the relationship between dietary inflammatory index (DII) and risk of ocular diseases, including glaucoma, cataract, age-related macular degeneration (ARMD), and diabetic retinopathy.

METHODS

We used the National Health and Nutrition Examination Survey (NHANES) data from 2005 to 2008 to conduct this study. The correlation between DII and risk of ocular diseases was examined using weighted multivariable logistic regression analysis, restricted cubic spline (RCS) plots, and subgroup analysis.

RESULTS

In total, 2885 participants from the NHANES database were included. The DII scores were divided into four group: Q1 (- 4.438-0.386), Q2 (0.387-1.848), Q3 (1.849-3.073), and Q4 (3.074-4.970). RCS shown that there was a U-shaped correlation between DII and prevalence of glaucoma, cataract, ARMD, and diabetic retinopathy. After adjusting for underlying confounding variables, compared to Q1 group, the odd ratios (ORs) with 95 percent confidence intervals (CIs) for glaucoma, cataract, ARMD, and diabetic retinopathy across the quartiles were [0.97 (0.54, 1.75), 1.20 (0.68, 2.11), and 1.29 (0.73, 2.30)], [0.87 (0.56, 1.35), 1.12 (0.73, 1.73), and 1.16 (0.75, 1.80)], [0.85 (0.53, 1.36), 0.66 (0.40, 1.09), and 0.97 (0.61, 1.56)] and [0.86 (0.63, 1.18), 0.89 (0.65, 1.22), and 1.04 (0.75, 1.45)] for DII, respectively.

CONCLUSIONS

Reducing the intake of pro-inflammatory foods may be an effective measure to prevent the onset of ocular disease, including glaucoma, cataract, ARMD, and diabetic retinopathy. However, eating only anti-inflammatory foods is not the best choice.

Dynamic Complement Protein Changes in Aqueous Humor and Plasma of Patients With Retinal Vein Occlusion During Ranibizumab Treatment

Purpose

To assess dynamic changes of complement protein in aqueous humor (AH) and plasma of retinal vein occlusion (RVO) patients during ranibizumab treatment, and to explore the differential expression of complement proteins in branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO).

Patients and Methods

This prospective, consecutive case series study collected AH and plasma samples from 27 RVO patients at baseline, 1 and 2 months after ranibizumab treatment, including 19 BRVO and 8 CRVO patients. The concentrations of 13 complement proteins and vascular endothelial growth factor A (VEGF-A) were measured using Luminex® × MAP® technology.

Results

During ranibizumab treatment, a reduction in the levels of C1q (p < 0.001), C2 (p = 0.030), C4 (p = 0.001), C4b (p = 0.026), C3b/iC3b (p < 0.001), C5 (p = 0.007), C5a (p = 0.005), CFD (p = 0.022), CFH (p < 0.001), and CFI (p < 0.001) in AH was observed. No significant changes were observed in the plasma levels of all measured factors. At baseline, CRVO had higher levels of C4 (p = 0.003), C4b (p < 0.001), C3b/iC3b (p < 0.001), C5 (p = 0.020), C5a (p = 0.007), CFD (p = 0.002), CFH (p < 0.001), and CFI (p < 0.001) in AH compared to BRVO.

Conclusion

Ranibizumab treatment reduced the intraocular but not circulating activation of classical and alternative complement pathways in RVO patients. Differences in intraocular complement proteins were observed between BRVO and CRVO patients, which may reflect different pathogenesis.

CAMK2D and Complement Factor I-Involved Calcium/Calmodulin Signaling Modulates Sodium Iodate-Induced Mouse Retinal Degeneration

Purpose

To investigate the effect of Ca2+/calmodulin-dependent protein kinase II (CAMKII) δ subtypes (CAMK2D) on sodium iodate (NaIO3)-induced retinal degeneration in mice.

Methods

Bioinformatics analysis and Western blot experiments were used to screen the significantly differentially expressed genes in age-related macular degeneration (AMD) disease. CAMK2D knockdown and overexpression models were constructed by lentivirus (LV) infection of adult retinal pigment epithelial cell line-19 (ARPE-19) cells in vitro. Flow cytometry was used to detect ARPE-19 cell apoptosis induced by NaIO3. In vivo, CAMK2D knockdown and overexpression mouse models were generated by infecting mouse retinal pigment epithelium (RPE) with adeno-associated virus (AAV). Retinography, optical coherence tomography (OCT), and histological analysis (hematoxylin and eosin staining) were used to detect NaIO3-induced retinal structural changes in mice. Electroretinography (ERG) was used to detect NaIO3-induced retinal function changes in mice. TdT-mediated dUTP nick-end labeling (TUNEL) staining was used to detect the apoptosis of retinal cells induced by NaIO3. RNA sequencing (RNA-Seq) and bioinformatics analysis were used to screen for target genes affected by CAMK2D in CAMK2D-overexpressing ARPE-19 cells. And flow cytometry, OCT, and ERG were used to evaluate the regulatory effect of CAMK2D on target genes.

Results

Bioinformatics analysis found the expression of genes related to Ca2+ signal was significantly reduced in AMD patients. Western blot showed that in a mouse model of dry AMD induced by NaIO3, CAMK2D expression in RPE-Choroid tissue significantly lower than normal mice. In vitro, our results showed that overexpression of CAMK2D in ARPE-19 cells decreased apoptosis induced by NaIO3 and knockdown increased apoptosis. In vivo, CAMK2D overexpression in RPE cells can attenuate the retina degeneration induced by NaIO3 and CAMK2D knockdown aggravated degeneration. The bioinformatics analysis indicated that CAMK2D might affect AMD pathology through complement factor I (CFI). In vitro, knockdown of CFI in ARPE-19 cells increased apoptosis induced by NaIO3. In knockdown CFI ARPE-19 cells, overexpression of CAMK2D reduced the above apoptosis. In mice retina, CFI knockdown can aggravate the retina degeneration induced by NaIO3. In knockdown CFI mice, overexpression of CAMK2D in RPE can attenuate the above retina degeneration. Western blot confirmed that CAMK2D regulated the expression of CFI in mice.

Conclusions

CAMK2D can attenuate the retinal degeneration induced by NaIO3, which was achieved by regulating the CFI.

Multiple gene therapy as a tool for regulating the expression of molecules involved in neovascular age-related macular degeneration

Anti-vascular endothelial growth factor (VEGF) therapies have revolutionized the treatment of neovascular age-related macular degeneration (nAMD) and other retinal diseases. However, the necessity for repeated intravitreal injections and the observation of variable treatment responses calls for new treatment modalities where fewer and more effective interventions can result in a clinical effect. Gene therapy might be such an alternative, and therefore the development and clinical application of gene therapy aimed at modifying gene expression has received considerable attention. The article reviews current knowledge of the background, pathophysiological mechanisms, technologies, limitations, and future directions for gene therapy aimed at modifying the synthesis of compounds involved in acquired and senescent retinal disease. The authors have contributed to the field by developing gene therapy to reduce the expression of vascular endothelial growth factor (VEGF), as well as multiple gene therapy for simultaneous downregulation of the synthesis of VEGF and upregulation of pigment epithelium-derived factor (PEDF) using adeno-associated virus (AAV) vectors. It is suggested that such multi-target gene therapy might be included in future treatments of retinal diseases where the underlying mechanisms are complex and cannot be attributed to one specific mediator. Such diseases might include dry AMD (dAMD) with geographic atrophy, but also diabetic macular edema (DME) and retinal vein occlusion (RVO). Gene therapy can be expected to be most beneficial for the patients in need of multiple intra-vitreal injections and in whom the therapeutic response is insufficient. It is concluded, that in parallel with basic research, there is a need for clinical studies aimed at identifying factors that can be used to identify patients who will benefit from gene therapy already at the time of diagnosis of the retinal disease.

Retinopathy in Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a multisystemic disease, i.e., influencing various organ systems beyond the liver and, thus, contributing to comorbidities. Characterized by excessive fat accumulation in the hepatocytes, MASLD is frequently linked to metabolic syndrome components, such as obesity, insulin resistance, dyslipidemia, and hypertension. Therefore, exploring the intricate connection between MASLD and other organ systems, including the eyes, seems to be essential. In this context, retinopathy has been investigated for its potential association with MASLD, since both conditions share common pathogenetic pathways. Chronic low-grade inflammation, oxidative stress, insulin resistance, and endothelial dysfunction are only some of those mechanisms contributing to disease progression and, possibly, determining the bidirectional interplay between the liver and retinal pathology. This narrative review aims to summarize data concerning the multisystemicity of MASLD, primarily focusing on its potential association with the eyes and, particularly, retinopathy. Identifying this possible association may emphasize the need for early screening and integrated management approaches that address the liver and eyes as interconnected components within the framework of a systemic disease. Further research is necessary to delineate the precise mechanisms and develop targeted interventions to mitigate the bidirectional impact between the liver and eyes, aiming to reduce the overall burden of disease and improve patient outcomes.

Productive infection of the retinal pigment epithelium by SARS-CoV-2: Initial effects and consideration of long-term consequences

As the SARS-CoV-2 coronavirus continues to evolve and infect the global population, many individuals are likely to suffer from post-acute sequelae of SARS-CoV-2 infection (PASC). Manifestations of PASC include vision symptoms, but little is known about the ability of SARS-CoV-2 to infect and impact the retinal cells. Here, we demonstrate that SARS-CoV-2 can infect and perturb the retinal pigment epithelium (RPE) in vivo, after intranasal inoculation of a transgenic mouse model of SARS-CoV-2 infection, and in cell culture. Separate lentiviral studies showed that SARS-CoV-2 Spike protein mediates viral entry and replication in RPE cells, while the Envelope and ORF3a proteins induce morphological changes. Infection with major variants of SARS-CoV-2 compromised the RPE barrier function and phagocytic capacity. It also caused complement activation and production of cytokines and chemokines, resulting in an inflammatory response that spread across the RPE layer. This inflammatory signature has similarities to that associated with the onset of age-related macular degeneration (AMD), a major cause of human blindness, resulting from RPE pathology that eventually leads to photoreceptor cell loss. Thus, our findings suggest that post-acute sequelae of SARS-CoV-2 infection of the RPE may have long-term implications for vision, perhaps comparable to the increased occurrence of AMD found among individuals infected by HIV, but with greater public health consequences due to the much larger number of SARS-CoV-2 infections.

The Complement Factor H (Y402H) risk polymorphism for age-related macular degeneration affects metabolism and response to oxidative stress in the retinal pigment epithelium

Age-related macular degeneration (AMD), the leading cause of central vision loss in the elderly, involves death of the retinal pigment epithelium (RPE) and light-sensing photoreceptors. This multifactorial disease includes contributions from both genetic and environmental risk factors. The current study examined the effect of the Y402H polymorphism of Complement Factor H (CFH, rs1061170) and cigarette smoke, predominant genetic and environmental risk factors associated with AMD. We used targeted and discovery-based approaches to identify genotype-dependent responses to chronic oxidative stress induced by cigarette smoke extract (CSE) in RPE differentiated from induced pluripotent stem cells (iPSC) derived from human donors harboring either the low risk (LR) or high risk (HR) CFH genotype. Chronic CSE altered the metabolic profile in both LR and HR iPSC-RPE and caused a dose-dependent reduction in mitochondrial function despite an increase in mitochondrial content. Notably, cells with the HR CFH SNP showed a greater reduction in maximal respiration and ATP production. Significant genotype-dependent changes in the proteome were observed for HR RPE at baseline (cytoskeleton, MAPK signaling) and after CSE exposure, where a less robust upregulation of the antioxidants and significant downregulation in proteins involved in nucleic acid metabolism and membrane trafficking were noted compared to LR cells. In LR cells, uniquely upregulated proteins were involved in lipid metabolism and chemical detoxification. These genotype-dependent differences at baseline and in response to chronic CSE exposure suggest a broader role for CFH in modulating the response to oxidative stress in RPE and provides insight into the interaction between environmental and genetic factors in AMD pathogenesis.

The complement system in lipid-mediated pathologies

The complement system, a coordinator and facilitator of the innate immune response, plays an essential role in maintaining host homeostasis. It promotes clearance of pathogen- and danger-associated molecular patterns, regulates adaptive immunity, and can modify various metabolic processes such as energy expenditure, lipid metabolism, and glucose homeostasis. In this review, we will focus on the intricate interplay between complement components and lipid metabolism. More precisely, we will display how alterations in the activation and regulation of the complement system affect pathological outcome in lipid-associated diseases, such as atherosclerosis, obesity, metabolic syndrome, age-related macular degeneration, and metabolic dysfunction-associated steatotic liver disease. In addition to that, we will present and evaluate underlying complement-mediated physiological mechanisms, observed both in vitro and in vivo. Our manuscript will demonstrate the clinical significance of the complement system as a bridging figure between innate immunity and lipid homeostasis.

Complement proteins and complement regulatory proteins are associated with age-related macular degeneration stage and treatment response

BACKGROUND

Dysregulation of the complement system is involved in development of age-related macular degeneration (AMD). The complement cascade is regulated by membrane bound complement regulatory proteins (Cregs) on mononuclear leukocytes among others. This study aims to investigate systemic complement proteins and Cregs in AMD stages and their association with treatment response in neovascular AMD (nAMD).

METHODS

In this clinical prospective study, treatment-naïve patients with nAMD, intermediate AMD (iAMD) and healthy controls were recruited and systemic complement proteins C3, C3a and C5a were investigated with electrochemiluminescence immunoassays, and Creg expression (CD35, CD46 and CD59) on T cells (CD4 + and CD8+) and monocytes (classical, intermediate and non-classical) investigated with flow cytometry. Treatment response in nAMD patients was evaluated after loading dose and after one year, and categorized as good, partial or poor. Complement proteins and Creg expression levels were compared between healthy controls, iAMD and nAMD, as well as between good, partial and poor nAMD treatment response groups. Polymorphisms in the CFH and ARMS2 genes were analyzed and compared to complement proteins and Creg expression levels in nAMD patients.

RESULTS

One hundred patients with nAMD, 34 patients with iAMD and 61 healthy controls were included. 94 nAMD patients completed the 1-year follow-up. Distribution of treatment response in nAMD was 61 (65%) good, 26 (28%) partial, and 7 (7%) poor responders. The distribution of 1-year treatment response was 50 (53%) good, 33 (36%) partial, and 11 (11%) poor responders. The concentrations of systemic C3, C3a, and the C3a/C3-ratio were significantly increased in patients with nAMD compared to healthy controls (P < 0.001, P = 0.002, and P = 0.035, respectively). Systemic C3 was also increased in iAMD compared to healthy controls (P = 0.031). The proportion of CD46 + CD4 + T cells and CD59 + intermediate monocytes were significantly decreased in patients with nAMD compared to healthy controls (P = 0.018 and P = 0.042, respectively). The post-loading dose partial treatment response group had significantly lower concentrations of C3a and C5a compared to the good response group (P = 0.005 and P = 0.042, respectively). The proportion of CD35 + monocytes was significantly lower in the 1-year partial response group compared to the 1-year good response group (P = 0.039). High-risk CFH genotypes in nAMD patients was associated with increased C3a, C3a/C3-ratio, and expression levels of CD35 + CD8 + T cells and CD46 + classical monocytes, while expression level of CD46 + non-classical monocytes was decreased.

CONCLUSION

Elevated concentrations of systemic complement proteins were found in patients with iAMD and nAMD. Decreased Creg expression levels were found in patients with nAMD. Partially responding nAMD patients had a dysregulated complement system and Cregs compared to good responders.

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.

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.

A high-fat plus high-sucrose diet induces age-related macular degeneration in an experimental rabbit model

Age-related macular degeneration (AMD) is a leading cause of blindness. Metabolic disorders and diets are risk factors. We compared lipid profiles and retinal phenotypes with long-term feeding of four diets in male Chinchilla rabbits. Animals were fed a normal diet (ND), high-fat diet (HFD), high-sucrose diet (HSD) or a high-fat plus high-sucrose diet (HFSD) for 6 months. Eyes were examined using multimodal imaging modalities and electroretinograms. Retinal sections were analyzed using H&E staining, Toluidine Blue staining, immunostaining and transmission electron microscopy. Lipids and complement C3 protein (C3) in serum or aqueous humor were measured. RNA sequencing was performed to evaluate the retinal transcriptomes. HFD and HSD had minor effects on lipid profiles but, when fed concomitantly, synergistically induced severe dyslipidemia. None of the four diets caused obesity. HFSD induced retinal lesions, such as reticular pseudodrusen (RPDs) and other pigmentary abnormalities. RPD-like lesions were mainly lipid droplets around cells of the retinal pigment epithelium. HFSD also induced elevated levels of ocular C3 and reduced the density of retinal vessels. In conclusion, HFD and HSD can - when combined - induce normal-weight dyslipidemia and RPD-like retinal lesions. HFSD-fed male Chinchilla rabbits are a good model of early AMD.

Retinal pigment epithelium-specific ablation of GPx4 in adult mice recapitulates key features of geographic atrophy in age-related macular degeneration

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss in the elderly population, particularly the late-stage of dry AMD known as geographic atrophy (GA), lacks effective treatment options. Genetic mouse models of AMD have revealed the significance of impaired lipid metabolism and anti-oxidative capacity in early/intermediate stage of AMD, but remains unclear in GA that severely damages visual function. Here, to investigate the potential relevance of peroxidized lipids in RPE for late-stage dry AMD, GPx4fl/fl mice underwent subretinal injections of RPE-specific AAV-Cre vector or control AAV vector. RPE-specific GPx4 deficiency led to rapid RPE degeneration resembling key features of late-stage dry AMD, including preceding loss of RPE cell polarity, accumulation of acrolein, malondialdehyde, and 4-hydroxynonenal, photoreceptor loss, lipofuscin-laden subretinal melanophage infiltration, and complement activation. Treatment with α-tocopherol and ferrostatin-1 mitigated RPE degeneration, and shrunk mitochondria were observed in GPx4 deficient mice, suggesting involvement of ferroptosis. Unexpectedly, necrostatin-1s, an inhibitor of necroptosis, also ameliorated RPE degeneration, and activation of RIP3 and MLKL along with inactivation of caspase-8 was observed, indicating crosstalk between ferroptosis and necroptosis pathways. Our findings shed light on the intricate mechanisms underlying RPE degeneration in AMD and highlight GPx4/lipid peroxidation as potential therapeutic targets. RPE-specific ablation of GPx4 in mice provides a valuable tool for further elucidating the interplay between lipid peroxidation, cell death pathways, and AMD pathogenesis, offering new insights for preclinical research and therapeutic development targeting GA.

Age-Related Macular Degeneration (AMD): Pathophysiology, Drug Targeting Approaches, and Recent Developments in Nanotherapeutics

The most prevalent reason for vision impairment in aging inhabitants is age-related macular degeneration (AMD), a posterior ocular disease with a poor understanding of the anatomic, genetic, and pathophysiological progression of the disease. Recently, new insights exploring the role of atrophic changes in the retinal pigment epithelium, extracellular drusen deposits, lysosomal lipofuscin, and various genes have been investigated in the progression of AMD. Hence, this review explores the incidence and risk factors for AMD, such as oxidative stress, inflammation, the complement system, and the involvement of bioactive lipids and their role in angiogenesis. In addition to intravitreal anti-vascular endothelial growth factor (VEGF) therapy and other therapeutic interventions such as oral kinase inhibitors, photodynamic, gene, and antioxidant therapy, as well as their benefits and drawbacks as AMD treatment options, strategic drug delivery methods, including drug delivery routes with a focus on intravitreal pharmacokinetics, are investigated. Further, the recent advancements in nanoformulations such as polymeric and lipid nanocarriers, liposomes, etc., intended for ocular drug delivery with pros and cons are too summarized. Therefore, the purpose of this review is to give new researchers an understanding of AMD pathophysiology, with an emphasis on angiogenesis, inflammation, the function of bioactive lipids, and therapy options. Additionally, drug delivery options that focus on the development of drug delivery system(s) via several routes of delivery can aid in the advancement of therapeutic choices.

Pinpointing Novel Plasma and Brain Proteins for Common Ocular Diseases: A Comprehensive Cross-Omics Integration Analysis

The pathogenesis of ocular diseases (ODs) remains unclear, although genome-wide association studies (GWAS) have identified numerous associated genetic risk loci. We integrated protein quantitative trait loci (pQTL) datasets and five large-scale GWAS summary statistics of ODs under a cutting-edge systematic analytic framework. Proteome-wide association studies (PWAS) identified plasma and brain proteins associated with ODs, and 11 plasma proteins were identified by Mendelian randomization (MR) and colocalization (COLOC) analyses as being potentially causally associated with ODs. Five of these proteins (protein-coding genes ECI1, LCT, and NPTXR for glaucoma, WARS1 for age-related macular degeneration (AMD), and SIGLEC14 for diabetic retinopathy (DR)) are newly reported. Twenty brain-protein-OD pairs were identified by COLOC analysis. Eight pairs (protein-coding genes TOM1L2, MXRA7, RHPN2, and HINT1 for senile cataract, WARS1 and TDRD7 for AMD, STAT6 for myopia, and TPPP3 for DR) are newly reported in this study. Phenotype-disease mapping analysis revealed 10 genes related to the eye/vision phenotype or ODs. Combined with a drug exploration analysis, we found that the drugs related to C3 and TXN have been used for the treatment of ODs, and another eight genes (GSTM3 for senile cataract, IGFBP7 and CFHR1 for AMD, PTPMT1 for glaucoma, EFEMP1 and ACP1 for myopia, SIRPG and CTSH for DR) are promising targets for pharmacological interventions. Our study highlights the role played by proteins in ODs, in which brain proteins were taken into account due to the deepening of eye-brain connection studies. The potential pathogenic proteins finally identified provide a more reliable reference range for subsequent medical studies.

Complement Inhibitors for Geographic Atrophy in Age-Related Macular Degeneration-A Systematic Review

BACKGROUND/OBJECTIVES

Age-related macular degeneration (AMD) is one of the main causes of blindness and visual impairment worldwide. Intravitreal complement inhibitors are an emergent approach in the treatment of AMD, which have had encouraging results. This systematic review analyzes the outcomes and safety of complement inhibitor therapies for GA in AMD cases.

METHODS

A comprehensive search on the PubMed and Web of Science databases returned 18 studies involving various complement inhibitor agents, with a total of 4272 patients and a mean follow-up of 68.2 ± 20.4 weeks.

RESULTS

Most treated patients were white (96.8%) and female (55.8%), with a mean age of 78.3 ± 7.8 years and a mean GA area of 8.0 ± 3.9 mm2. There were no differences in visual function change between treated and control participants. The mean GA area change was 2.4 ± 0.7 mm2 in treated participants vs. 2.7 ± 0.8 mm2 in control groups (p < 0.001). The ocular and systemic side effects were similar to those of intravitreal anti-VEGF. A less-understood effect was that of the onset of choroidal neovascularization (CNV) in 1.1-13% of patients; this effect was found to be more frequent in patients with neovascular AMD in the fellow eye or nonexudative CNV in the study eye at baseline.

CONCLUSIONS

Complement inhibitors may represent a useful therapy for GA in AMD, but a personalized approach to patient selection is necessary to optimize the outcomes.

HIF Stabilizer Desidustat Protects against Complement-Mediated Diseases

Complement cascade is a defence mechanism useful for eliminating pathogenic microorganisms and damaged cells. However, activation of alternative complement system can also cause inflammation and promote kidney and retinal disease progression. Inflammation causes tissue hypoxia, which induces hypoxia-inducible factor (HIF) and HIF helps the body to adapt to inflammation. In this study, we investigated the effect of HIF stabilizer desidustat in complement-mediated diseases. Oral administration of desidustat (15 mg/kg) was effective to reduce the kidney injury in mice that was induced by either lipopolysaccharide (LPS), doxorubicin or bovine serum albumin (BSA)-overload. Complement activation-induced membrane attack complex (MAC) formation and factor B activity were also reduced by desidustat treatment. In addition, desidustat was effective against membranous nephropathy caused by cationic BSA and retinal degeneration induced by sodium iodate in mice. C3-deposition, proteinuria, malondialdehyde, and interleukin-1ß were decreased and superoxide dismutase was increased by desidustat treatment in cBSA-induced membranous nephropathy. Desidustat specifically inhibited alternative complement system, without affecting the lectin-, or classical complement pathway. This effect appears to be mediated by inhibition of factor B. These data demonstrate the potential therapeutic value of HIF stabilization by desidustat in treatment of complement-mediated diseases.

Exposure to per- and polyfluoroalkyl substances and age-related macular degeneration in U.S. middle-aged and older adults

Despite various health effects of per- and polyfluoroalkyl substances (PFAS) exposure, the association between PFAS exposure and age-related macular degeneration (AMD) has not been investigated. We aimed to assess associations of PFAS exposure with AMD, using data from 1722 U.S. adults aged 40 years or more participating in the National Health and Nutrition Examination Survey 2005-2008 with complete data on PFAS measurement, AMD diagnosis, and covariates. Serum concentrations of PFAS, including perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), and perfluorooctane sulfonic acid (PFOS), were measured. An overall PFAS burden score was calculated using item response theory scoring. Individual PFAS concentration and overall PFAS burden score were categorized into low (reference), medium, and high groups. Diagnosis of AMD was based on retinal image examination. Any AMD was defined as the presence of early or late AMD. Survey-weighted logistic regression adjusted for potential confounders was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for presence of AMD according to PFAS exposure. Overall, 132 (6.5%) individuals were diagnosed as any AMD, including 115 (5.7%) individuals with early AMD. A significant dose-response association was observed between serum PFOS concentration and any AMD (p-trend = 0.03), with a significant OR of 1.99 (95% CI: 1.05, 3.79) for the high group compared to the reference. Overall PFAS burden showed a non-monotonic association with any AMD, with a significant OR of 2.18 (95% CI: 1.18, 4.04) for the medium. Inverted U-shaped associations were observed by restricted cubic spline analyses. Also, early AMD showed similar patterns in PFOS and overall PFAS burden and additionally an inverted U-shape association in PFNA. Our findings suggest that exposure to PFAS estimated by serum PFOS and PFNA as well as overall PFAS burden might be a risk factor for AMD in middle-aged and older population.

Gene Therapies in Clinical Development to Treat Retinal Disorders

Gene therapies have emerged as promising treatments in clinical development for various retinal disorders, offering hope to patients with inherited degenerative eye conditions. Several gene therapies have already shown remarkable success in clinical trials, with significant improvements observed in visual acuity and the preservation of retinal function. A multitude of gene therapies have now been delivered safely in human clinical trials for a wide range of inherited retinal disorders but there are some gaps in the reported trial data. Some of the most exciting treatment options are not under peer review and information is only available in press release form. Whilst many trials appear to have delivered good outcomes of safety, others have failed to meet primary endpoints and therefore not proceeded to phase III. Despite this, such trials have enabled researchers to learn how best to assess and monitor patient outcomes, which will guide future trials to greater success. In this review, we consider recent and ongoing clinical trials for a variety of potential retinal gene therapy treatments and discuss the positive and negative issues related to these trials. We discuss the treatment potential following clinical trials as well as the potential risks of some treatments under investigation. As these therapies continue to advance through rigorous testing and regulatory approval processes, they hold the potential to revolutionise the landscape of retinal disorder treatments, providing renewed vision and enhancing the quality of life for countless individuals worldwide.

Gene and cell therapy for age-related macular degeneration: A review

Age-related macular degeneration (AMD) is the most common cause of irreversible vision loss among the elderly in Western communities, with an estimated global prevalence of 10 - 20% in people older than 65 years. AMD leads to central vision loss due to degeneration of the photoreceptors, retinal pigment epithelium and the choriocapillaris. Beckman's classification for AMD, based upon color fundus photographs, divides the disease into early, intermediate, and late forms. The late, vision-threatening stage includes both neovascular AMD and geographic atrophy. Despite its high prevalence and impact on patients' quality of life, treatment options for AMD are limited. While neovascular AMD can be medically managed with anti-VEGF intravitreal injections, until very recently there has been no approved treatment options for atrophic AMD; however, in February 2023 the first treatment for geographic atrophy - pegcetacoplan - was approved by the US FDA. We describe the current landscape of potential gene and cell therapeutic strategies for late-stage AMD, with an emphasis on the therapeutic options that might become available in the next few years.

Association between age-related macular degeneration and risk of incident cancer

BACKGROUND/AIMS

Age-related macular degeneration (AMD) and cancer may share similar risk factors, indicating possible common pathogenic pathways. We aimed to describe the site-specific cancer risk based on the relationship of AMD with visual disability (VD) status.

METHODS

This was a population-based cohort study using data from the Korean National Health Insurance Service database (2009-2019) including patients who participated in a national health screening programme in 2009. The subjects were categorised based on the presence of AMD and VD. The occurrence of cancer was identified using principal diagnosis according to the International Classification of Disease, 10th revision codes in claims data. The Cox regression hazard model was used to compare HRs of site-specific cancer.

RESULTS

Among 4 088 814 participants, 51 596 had AMD of which 3683 subjects had VD. The mean follow-up period was 9.6 years. The overall cancer risk was generally null, but the risk of hypervascular cancer such as thyroid cancer (adjusted HR (aHR) 1.10, 95% CI 1.00 to 1.20) and renal cancer (aHR 1.16, 95% CI 1.00 to 1.33) was higher and the risk of stomach cancer (aHR 0.89, 95% CI 0.84 to 0.94) was lower in the AMD group than in the non-AMD group.

CONCLUSION

This study demonstrated a possible association between AMD and several cancers. Increased renal and thyroid cancer risk among patients with AMD could indicate that AMD is associated with hypervascular cancer. Further studies in which additional databases are used and the underlying detailed mechanisms evaluated are needed to validate our results.

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.

RPE melanin and its influence on the progression of AMD

OBJECTIVE

The aim of this review article is to summarize the latest findings and current understanding of the origin of melanin in the retinal pigment epithelium (RPE), its function within the RPE, its role in the pathogenesis of age-related macular degeneration (AMD), its effect on retinal development, and its potential therapeutic benefit in the treatment of AMD.

METHODS

A comprehensive search of peer-reviewed journals was conducted using various combinations of key terms such as "melanin," "retinal pigment epithelium" or "RPE," "age-related macular degeneration" or AMD," "lipofuscin," "oxidative stress," and "albinism." Databases searched include PubMed, Scopus, Science Direct, and Google Scholar. 147 papers published between the years of 1957 and 2023 were considered with an emphasis on recent findings.

SUMMARY OF FINDINGS

AMD is thought to result from chronic oxidative stress within the RPE that results in cellular dysfunction, metabolic dysregulation, inflammation, and lipofuscin accumulation. Melanin functions as a photoscreener, free radical scavenger, and metal cation binding reservoir within the RPE. RPE melanin does not regenerate, and it undergoes degradation over time in response to chronic light exposure and oxidative stress. RPE melanin is important for retinal development and RPE function, and in the aging eye, melanin loss is associated with increased lipid peroxidation, inflammation, and the accumulation of toxic oxidized cellular products. Therefore, melanin-based treatments may serve to preserve RPE and retinal function in AMD.

CONCLUSIONS

The pathogenesis of AMD is not fully understood, but RPE dysfunction and melanin loss in response to chronic oxidative stress and inflammation are thought to be primary drivers of the disease. Due to melanin's antioxidative effects, melanin-based nanotechnology represents a promising avenue for the treatment of AMD.

Potential role of CTSS in AMDImmune modulatory and anti-angiogenic effects of cathepsin S knockdown in ARPE-19 cells

We aimed to determine the role of cathepsin S (CTSS) in modulating oxidative stress-induced immune and inflammatory reactions and angiogenesis in age-related macular degeneration. Human retinal pigment epithelium cells line ARPE-19 (immature) were maintained and treated with H2O2. The expression of CTSS, inflammatory cytokines, and complement factors induced by oxidative stress was compared between cells incubated without (control) and with CTSS knockdown (using small interfering ribonucleic acid; siRNA). To evaluate the role of CTSS in angiogenesis, we assayed tube formation using human umbilical vein endothelial cells and conditioned medium from ARPE-19 cells. We also used a mouse model of laser-induced choroidal neovascularization. CTSS levels were higher in ARPE-19 cells treated with H2O2 than in control cells. Oxidative stress-induced CTSS resulted in significantly elevated transcription of nuclear factor kappa B-dependent inflammatory cytokines, complement factors C3a and C5a, membrane attack complex (C5b-9), and C3a and C5a receptors. siRNA-mediated knockdown of CTSS reduced the number of inflammatory signals. Furthermore, oxidative stress-induced CTSS regulated the expression of peroxisome proliferator-activated receptor γ and vascular endothelial growth factor A/Akt serine/threonine kinase family signaling, which led to angiogenesis. Tube formation assays and mouse models of choroidal neovascularization revealed that CTSS knockdown ameliorated angiogenesis in vitro and in vivo. The present findings suggest that CTSS modulates the complement pathway, inflammatory reactions, and neovascularization, and that CTSS knockdown induces potent immunomodulatory effects. Hence, it could be a promising target for the prevention and treatment of early- and late-stage age-related macular degeneration.

Pre-Clinical Studies of a Novel Bispecific Fusion Protein Targeting C3b and VEGF in Neovascular and Nonexudative AMD Models

INTRODUCTION

KNP-301 is a bi-specific fragment crystallizable region (Fc) fusion protein, which inhibits both C3b and vascular endothelial growth factor (VEGF) simultaneously for patients with late-stage age-related macular degeneration (AMD). The present study evaluated in vitro potency, in vivo efficacy, intravitreal pharmacokinetics (IVT PK), and injectability of KNP-301.

METHODS

C3b and VEGF binding of KNP-301 were assessed by surface plasmon resonance (SPR) and enzyme-linked immunosorbent assay (ELISA), and cellular bioassays. A laser-induced choroidal neovascularization (CNV) model and a sodium iodate-induced nonexudative AMD model were used to test the in vivo efficacy of mouse surrogate of KNP-301. Utilizing fluorescein angiography (FA) and spectral-domain optical coherence tomography (SD-OCT) scans, the reduction in disease lesions were analyzed in a CNV mouse model. In the nonexudative AMD mouse model, outer nuclear layer (ONL) was assessed by immunofluorescence staining. Lastly, intravitreal pharmacokinetic study was conducted with New Zealand white rabbits via IVT administration of KNP-301 and injectability of KNP-301 was examined by a viscosity test at high concentrations.

RESULTS

KNP-301 bound C3b selectively, which resulted in a blockade of the alternative pathway, not the classical pathway. KNP-301 also acted as a VEGF trap, impeding VEGF-mediate signaling. Our dual-blockade strategy was effective in both neovascular and nonexudative AMD models. Moreover, KNP-301 had an advantage of potentially less frequent dosing due to the long half-life in the intravitreal chamber. Our viscosity assessment confirmed that KNP-301 meets the criteria of the IVT injection.

CONCLUSIONS

Unlike current therapies, KNP-301 is expected to cover patients with late-stage AMD of both neovascular and nonexudative AMD, and its long-term PK profile at the intravitreal chamber would allow convenience in the dosing interval of patients.

Propensity-Matched Analysis of the Risk of Age-Related Macular Degeneration with Systemic Immune-Mediated Inflammatory Disease

PURPOSE

The pathogenesis of age-related macular degeneration (AMD) involves aberrant complement activation and is a leading cause of vision loss worldwide. Complement aberrations are also implicated in many systemic immune-mediated inflammatory diseases (IMIDs), but the relationship between AMD and these conditions remains undescribed. The aim of this study is to first assess the association between AMD and IMIDs, and then assess the risk of AMD in patients with specific IMIDs associated with AMD.

DESIGN

Cross-sectional study and cohort study.

SUBJECTS AND CONTROLS

Patients with AMD were compared with control patients with cataracts and no AMD to ensure evaluation by an ophthalmologist. Patients with IMIDs were compared with patients without IMIDs but with cataracts.

METHODS

This study used deidentified data from a national database (2006-2023), using International Classification of Diseases 10 codes to select for IMIDs. Propensity score matching was based on patients on age, sex, race, ethnicity, and smoking. Odds ratios were generated for IMIDs and compared between AMD and control patients. For IMIDs associated with AMD, the risk of AMD in patients with the IMID versus patients without IMIDs was determined utilizing a cohort study design.

MAIN OUTCOME MEASURES

Odds ratio of IMID, risk ratios (RRs), and 95% confidence intervals (CIs) of AMD diagnosis, given an IMID.

RESULTS

After propensity score matching, AMD and control cohorts (n = 217 197 each) had a mean ± standard deviation age of 74.7 ± 10.4 years, were 56% female, and 9% of patients smoked. Age-related macular degeneration showed associations with systemic lupus erythematosus (SLE), Crohn's disease, ulcerative colitis, rheumatoid arthritis (RA), psoriasis, sarcoidosis, scleroderma, giant cell arteritis, and vasculitis. Cohorts for each positively associated IMID were created and matched to control cohorts with no IMID history. Patients with RA (RR, 1.40; 95% CI, 1.30-1.49), SLE (RR, 1.73; 95% CI, 1.37-2.18), Crohn's disease (RR, 1.42; 95% CI, 1.20-1.71), ulcerative colitis (RR, 1.45; 95% CI, 1.29-1.63), psoriasis (RR, 1.48; 95% CI, 1.37-1.60), vasculitis (RR, 1.48; 95% CI, 1.33-1.64), scleroderma (RR, 1.65; 95% CI, 1.35-2.02), and sarcoidosis (RR, 1.42; 95% CI, 1.24-1.62) showed a higher risk of developing AMD compared with controls.

CONCLUSIONS

The results suggest that there is an increased risk of developing AMD in patients with RA, SLE, Crohn's disease, ulcerative colitis, psoriasis, vasculitis, scleroderma, and sarcoidosis compared with patients with no IMIDs.

FINANCIAL DISCLOSURE(S)

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

The ABCs of Stargardt disease: the latest advances in precision medicine

Stargardt disease (STGD) is the most common form of inherited juvenile macular dystrophy and is caused by sequence variants in the ABCA4 gene. Due to its genetic complexity and phenotypic variability, STGD poses significant therapeutic challenges. In the past decade, a lot of progress has been made regarding our understanding of the molecular and clinical aspects of STGD, along with its mechanisms. This has led to the development of new therapies, and there are human clinical trials currently ongoing. This paper evaluates the emergence of pharmacological approaches targeting the visual cycle to mitigate retinal damage, the role of gene therapy in correcting specific genetic defects, and the use of stem cell therapies aimed at retinal regeneration by showcasing the latest clinical trials and precision medicine approaches.

Retinal debris triggers cytotoxic damage in cocultivated primary porcine RPE cells

Introduction

One of the most common causes of vision loss in the elderly population worldwide is age-related macular degeneration (AMD). Subsequently, the number of people affected by AMD is estimated to reach approximately 288 million by the year 2040. The aim of this study was to develop an ex vivo model that simulates various aspects of the complex AMD pathogenesis.

Methods

For this purpose, primary porcine retinal pigment epithelial cells (ppRPE) were isolated and cultured. One group was exposed to medium containing sodium iodate (NaIO3) to induce degeneration. The others were exposed to different supplemented media, such as bovine serum albumin (BSA), homogenized porcine retinas (HPR), or rod outer segments (ROOS) for eight days to promote retinal deposits. Then, these ppRPE cells were cocultured with porcine neuroretina explants for another eight days. To assess the viability of ppRPE cells, live/dead assay was performed at the end of the study. The positive RPE65 and ZO1 area was evaluated by immunocytochemistry and the expression of RLBP1, RPE65, and TJP1 was analyzed by RT-qPCR. Additionally, drusen (APOE), inflammation (ITGAM, IL6, IL8, NLRP3, TNF), oxidative stress (NFE2L2, SOD1, SOD2), and hypoxia (HIF1A) markers were investigated. The concentration of the inflammatory cytokines IL-6 and IL-8 was determined in medium supernatants from day 16 and 24 via ELISA.

Results

Live/dead assay suggests that especially exposure to NaIO3 and HPR induced damage to ppRPE cells, leading in a significant ppRPE cell loss. All supplemented media resulted in decreased RPE-characteristic markers (RPE65; ZO-1) and gene expression like RLBP1 and RPE65 in the cultured ppRPE cells. Besides, some inflammatory, oxidative as well as hypoxic stress markers were altered in ppRPE cells cultivated with NaIO3. The application of HPR induced an enhanced APOE expression. Pre-exposure of the ppRPE cells led to a diminished number of cones in all supplemented media groups compared to controls.

Discussion

Overall, this novel coculture model represents an interesting initial approach to incorporating deposits into coculture to mimic AMD pathogenesis. Nevertheless, the effects of the media used need to be investigated in further studies.

Corneal application of SOCS1/3 peptides for the treatment of eye diseases mediated by inflammation and oxidative stress

Several blinding diseases affecting the retina and optic nerve are exacerbated by or caused by dysregulated inflammation and oxidative stress. These diseases include uveitis, age related macular degeneration, diabetic retinopathy and glaucoma. Consequently, despite their divergent symptoms, treatments that reduce oxidative stress and suppress inflammation may be therapeutic. The production of inflammatory cytokines and their activities are regulated by a class of proteins termed Suppressors of Cytokine Signaling (SOCS). SOCS1 and SOCS3 are known to dampen signaling via pathways employing Janus kinases and signal transducer and activator of transcription proteins (JAK/STAT), Toll-like Receptors (TLR), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), mitogen activated kinase (MAPK) and NLR family pyrin domain containing 3 (NLRP3). We have developed cell-penetrating peptides from the kinase inhibitory region of the SOCS1 and SOCS3 (denoted as R9-SOCS1-KIR and R9-SOCS3-KIR) and tested them in retinal pigment epithelium (RPE) cells and in macrophage cell lines. SOCS-KIR peptides exhibited anti-inflammatory, anti-oxidant and anti-angiogenic properties. In cell culture, both Th1 and Th17 cells were suppressed together with the inhibition of other inflammatory markers. We also observed a decrease in oxidants and a simultaneous rise in neuroprotective and anti-oxidant effectors. In addition, treatment prevented the loss of gap junction proteins and the ensuing drop in transepithelial electrical resistance in RPE cells. When tested in mouse models by eye drop instillation, they showed protection against autoimmune uveitis, as a prophylactic as well as a therapeutic. Mice with endotoxin-induced uveitis were protected by eye drop administration as well. R9-SOCS3-KIR was particularly effective against the pathways acting through STAT3, e.g. IL-6 and VEGF-A mediated responses that lead to macular degeneration. Eye drop administration of R9-SOCS3-KIR stimulated production of antioxidant effectors and reduced clinical symptoms in mouse model of oxidative stress that replicates the RPE injury occurring in AMD. Because these peptides suppress multiple pathogenic stimuli and because they can be delivered topically to the cornea, they are attractive candidates for therapeutics for uveitis, macular degeneration, diabetic retinopathy and glaucoma.

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.

Polyunsaturated Fatty Acid - mediated Cellular Rejuvenation for Reversing Age-related Vision Decline

The retina is uniquely enriched in polyunsaturated fatty acids (PUFAs), which are primarily localized in cell membranes, where they govern membrane biophysical properties such as diffusion, permeability, domain formation, and curvature generation. During aging, alterations in lipid metabolism lead to reduced content of very long-chain PUFAs (VLC-PUFAs) in the retina, and this decline is associated with normal age-related visual decline and pathological age-related macular degeneration (AMD). ELOVL2 (Elongation of very-long-chain fatty acids-like 2) encodes a transmembrane protein that produces precursors to docosahexaenoic acid (DHA) and VLC-PUFAs, and methylation level of its promoter is currently the best predictor of chronological age. Here, we show that mice lacking ELOVL2-specific enzymatic activity (Elovl2 C234W ) have impaired contrast sensitivity and slower rod response recovery following bright light exposure. Intravitreal supplementation with the direct product of ELOVL2, 24:5n-3, in aged animals significantly improved visual function and reduced accumulation of ApoE, HTRA1 and complement proteins in sub-RPE deposits. At the molecular level, the gene expression pattern observed in retinas supplemented with 24:5n-3 exhibited a partial rejuvenation profile, including decreased expression of aging-related genes and a transcriptomic signature of younger retina. Finally, we present the first human genetic data showing significant association of several variants in the human ELOVL2 locus with the onset of intermediate AMD, underlying the translational significance of our findings. In sum, our study identifies novel therapeutic opportunities and defines ELOVL2 as a promising target for interventions aimed at preventing age-related vision loss.

Clinical exome analysis and targeted gene repair of the c.1354dupT variant in iPSC lines from patients with PROM1-related retinopathies exhibiting diverse phenotypes

BACKGROUND

Inherited retinal dystrophies (IRD) are one of the main causes of incurable blindness worldwide. IRD are caused by mutations in genes that encode essential proteins for the retina, leading to photoreceptor degeneration and loss of visual function. IRD generates an enormous global financial burden due to the lack of understanding of a significant part of its pathophysiology, molecular diagnosis, and the near absence of non-palliative treatment options. Patient-derived induced pluripotent stem cells (iPSC) for IRD seem to be an excellent option for addressing these questions, serving as exceptional tools for in-depth studies of IRD pathophysiology and testing new therapeutic approaches.

METHODS

From a cohort of 8 patients with PROM1-related IRD, we identified 3 patients carrying the same variant (c.1354dupT) but expressing three different IRD phenotypes: Cone and rod dystrophy (CORD), Retinitis pigmentosa (RP), and Stargardt disease type 4 (STGD4). These three target patients, along with one healthy relative from each, underwent comprehensive ophthalmic examinations and their genetic panel study was expanded through clinical exome sequencing (CES). Subsequently, non-integrative patient-derived iPSC were generated and fully characterized. Correction of the c.1354dupT mutation was performed using CRISPR/Cas9, and the genetic restoration of the PROM1 gene was confirmed through flow cytometry and western blotting in the patient-derived iPSC lines.

RESULTS

CES revealed that 2 target patients with the c.1354dupT mutation presented monoallelic variants in genes associated with the complement system or photoreceptor differentiation and peroxisome biogenesis disorders, respectively. The pluripotency and functionality of the patient-derived iPSC lines were confirmed, and the correction of the target mutation fully restored the capability of encoding Prominin-1 (CD133) in the genetically repaired patient-derived iPSC lines.

CONCLUSIONS

The c.1354dupT mutation in the PROM1 gene is associated to three distinct AR phenotypes of IRD. This pleotropic effect might be related to the influence of monoallelic variants in other genes associated with retinal dystrophies. However, further evidence needs to be provided. Future experiments should include gene-edited patient-derived iPSC due to its potential as disease modelling tools to elucidate this matter in question.

Complement C3 is downregulated following ranibizumab intervention in experimental central retinal vein occlusion

Purpose

Ranibizumab is a frequently used inhibitor of vascular endothelial growth factor (VEGF) in the treatment of macular edema following central retinal vein occlusion (CRVO). Studying proteins that mediate the beneficial effects of ranibizumab in CRVO can potentially lead to the improved management of macular edema.

Methods

In 14 Danish Landrace pigs, experimental CRVO was induced in the right eyes and treated with either intravitreal ranibizumab (n = 6) or an intravitreal sodium chloride 9 mg/mL solution as a sham injection (n = 8). Successful CRVO was confirmed by fluorescein angiography. Retinal samples were collected 15 days after induced CRVO and analyzed with label-free, quantification, nano-liquid chromatography-tandem mass spectrometry. Validation was performed with western blotting and immunohistochemistry.

Results

CRVO was successfully induced and confirmed by fluorescein angiography. A total of 28 proteins were upregulated, and 31 proteins were downregulated following ranibizumab treatment. A high concentration of the ranibizumab component immunoglobulin kappa chain C region was observed in retinas treated with ranibizumab. Complement C3, the Ig lambda chain C region, and nucleobindin-2 were downregulated following ranibizumab intervention. The downregulation of complement C3 was confirmed by western blotting. Modest changes were observed in the remaining significantly regulated proteins.

Conclusions

Retinal complement C3 was downregulated following ranibizumab intervention in CRVO. The decrease in complement C3 may potentially downregulate the inflammatory response in CRVO. A high retinal concentration of ranibizumab was reached 15 days after injection of the compound.

Construction of a screening system for lipid-derived radical inhibitors and validation of hit compounds to target retinal and cerebrovascular diseases

Recent studies have highlighted the indispensable role of oxidized lipids in inflammatory responses, cell death, and disease pathogenesis. Consequently, inhibitors targeting oxidized lipids, particularly lipid-derived radicals critical in lipid peroxidation, which are known as radical-trapping antioxidants (RTAs), have been actively pursued. We focused our investigation on nitroxide compounds that have rapid second-order reaction rate constants for reaction with lipid-derived radicals. A novel screening system was developed by employing competitive reactions between library compounds and a newly developed profluorescence nitroxide probe with lipid-derived radicals to identify RTA compounds. A PubMed search of the top hit compounds revealed their wide application as repositioned drugs. Notably, the inhibitory efficacy of methyldopa, selected from these compounds, against retinal damage and bilateral common carotid artery stenosis was confirmed in animal models. These findings underscore the efficacy of our screening system and suggest that it is an effective approach for the discovery of RTA compounds.

Comprehensive functional characterization of complement factor I rare variant genotypes identified in the SCOPE geographic atrophy cohort

Rare variants (RVs) in the gene encoding the regulatory enzyme complement factor I (CFI; FI) that reduce protein function or levels increase age-related macular degeneration risk. A total of 3357 subjects underwent screening in the SCOPE natural history study for geographic atrophy secondary to age-related macular degeneration, including CFI sequencing and serum FI measurement. Eleven CFI RV genotypes that were challenging to categorize as type I (low serum level) or type II (normal serum level, reduced enzymatic function) were characterized in the context of pure FI protein in C3b and C4b fluid phase cleavage assays and a novel bead-based functional assay (BBFA) of C3b cleavage. Four variants predicted or previously characterized as benign were analyzed by BBFA for comparison. In all, three variants (W51S, C67R, and I370T) resulted in low expression. Furthermore, four variants (P64L, R339Q, G527V, and P528T) were identified as being highly deleterious with IC50s for C3b breakdown >1 log increased versus the WT protein, while two variants (K476E and R474Q) were ∼1 log reduced in function. Meanwhile, six variants (P50A, T203I, K441R, E548Q, P553S, and S570T) had IC50s similar to WT. Odds ratios and BBFA IC50s were positively correlated (r = 0.76, p < 0.01), while odds ratios versus combined annotation dependent depletion (CADD) scores were not (r = 0.43, p = 0.16). Overall, 15 CFI RVs were functionally characterized which may aid future patient stratification for complement-targeted therapies. Pure protein in vitro analysis remains the gold standard for determining the functional consequence of CFI RVs.

The Complement System as a Therapeutic Target in Retinal Disease

The complement cascade is a vital system in the human body's defense against pathogens. During the natural aging process, it has been observed that this system is imperative for ensuring the integrity and homeostasis of the retina. While this system is critical for proper host defense and retinal integrity, it has also been found that dysregulation of this system may lead to certain retinal pathologies, including geographic atrophy and diabetic retinopathy. Targeting components of the complement system for retinal diseases has been an area of interest, and in vivo, ex vivo, and clinical trials have been conducted in this area. Following clinical trials, medications targeting the complement system for retinal disease have also become available. In this manuscript, we discuss the pathophysiology of complement dysfunction in the retina and specific pathologies. We then describe the results of cellular, animal, and clinical studies targeting the complement system for retinal diseases. We then provide an overview of complement inhibitors that have been approved by the Food and Drug Administration (FDA) for geographic atrophy. The complement system in retinal diseases continues to serve as an emerging therapeutic target, and further research in this field will provide additional insights into the mechanisms and considerations for treatment of retinal pathologies.