Search Results (233)

Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss in older adults and is characterized by progressive dysfunction of the retinal pigment epithelium (RPE). Although genetic susceptibility and environmental exposure both contribute to disease risk, the mechanisms through which chronic metabolic and oxidative stress are integrated into sustained RPE dysfunction remain incompletely understood. Increasing evidence from human AMD donor tissue and experimental RPE models indicates that epigenetic regulation operates at the interface between mitochondrial dysfunction, redox imbalance, and transcriptional remodeling. This review synthesizes current findings on DNA methylation, chromatin accessibility, histone modification, and RNA-based regulation in AMD, with emphasis on their metabolic and mitochondrial context. Studies in human AMD-RPE demonstrate that epigenetic alterations are generally selective rather than global and frequently involve pathways related to mitochondrial maintenance, lipid metabolism, oxidative stress responses, and cellular homeostasis. Mechanistically, mitochondrial dysfunction and reactive oxygen species (ROS) may influence epigenetic regulation through altered Nicotinamide adenine dinucleotide (NAD⁺) availability, acetyl-CoA metabolism, redox-sensitive chromatin regulation, and modulation of DNA methyltransferase and histone deacetylase activity. Redox-sensitive pathways, including antioxidant signaling, further connect mitochondrial stress to adaptive or maladaptive transcriptional responses in the RPE. Importantly, while several interactions discussed are supported by findings in human AMD tissue, other components of the proposed epigenetic–mitochondrial–redox framework remain inferential or model-based and require further validation. Rather than acting as isolated disease triggers, epigenetic changes are more likely to function as stress-responsive regulatory layers that stabilize transcriptional states over time in a long-lived post-mitotic tissue. We further discuss unresolved questions regarding causality, reversibility, therapeutic feasibility, and stage-specific intervention strategies. Collectively, this framework positions the epigenetic–mitochondrial–redox axis as a unifying model for understanding RPE vulnerability and AMD progression. Full article

Background: The retinal pigment epithelium (RPE) plays a pivotal role in the visual process by maintaining the blood–retina barrier, protecting the retina from oxidative stress, and regulating immune responses. Consequently, dysfunction or degeneration of the RPE is implicated in a broad spectrum of retinal disorders that lead to progressive and irreversible vision loss. In this context, inflammation of the RPE has emerged as a critical factor in the pathogenesis of retinal degenerative diseases, underscoring its dual role as both a target and mediator of retinal inflammatory processes within the retina. Objectives: This study aims to preliminarily investigate, mainly by assessment of proinflammatory cytokine gene expression and immunoblotting, the molecular mechanisms underlying RPE inflammation induced by interactions between the RPE and microglia of the central nervous system. Methods/Results: Using in vitro models of human RPE cells, the ARPE 19 cell line was exposed to conditioned media from microglia (CHME-5 cell line) under basal and proinflammatory conditions. We observed increased activation of the MAPK signaling pathway, (evidenced by a 4-fold increase in the phosphorylation ratio of MEK and ERK) alongside elevated expression of proinflammatory cytokines, assessed by RT-PCR and immunoblotting, and a 2-fold increase in reactive oxygen species levels in RPE cells, evaluated by colorimetric assays, after exposure with conditioned media. Specifically, IL-1β and IL-8 levels increased more than 40-fold, while IL-6 expression showed a 4-fold increase compared to controls. Conclusions: These findings emphasize the central role of the RPE in retinal inflammation and suggest potential therapeutic targets to modulate immune responses and preserve retinal function. Full article

Gene editing, particularly CRISPR/Cas technology, represents a promising approach for the treatment of rare genetic diseases, including inherited retinal dystrophies, for which effective therapies are largely unavailable. Despite extensive research investigating gene editing across a wide range of cell types, transient delivery of CRISPR/Cas components and efficient homology-directed repair (HDR) in differentiated cells remain challenging. In this study, we employed hiPSCs derived from patients with Stargardt disease or Best disease, carrying pathogenic variants in ABCA4 or BEST1, respectively, to explore gene editing in human models. CRISPR/Cas9 and Cas12 nucleases were delivered into hiPS-derived retinal pigment epithelium (RPE) and retinal organoids using lipoplexes and compared with electroporation. We evaluated transfection efficiency, sgRNA-mediated DNA cleavage, and HDR-based correction. Precise repair of the pathogenic BEST1 variant was successfully achieved in hiPS-derived RPE cells using both nucleases, with Cas12 yielding the highest efficiency, exceeding 10% of HDR correction. Edited RPE cells preserved normal morphology and expressed specific maturity markers. In contrast, retinal organoids exhibited moderate transfection efficiency but showed no detectable CRISPR/Cas-induced DNA cleavage, highlighting the need for further optimization of gene editing in more complex cellular tissues. This study demonstrates, for the first time, precise correction of a single-nucleotide mutation in patient-derived RPE using CRISPR/Cas9 and Cas12 delivered using lipoplexes. These findings underscore the therapeutic potential of CRISPR/Cas-based strategies for inherited retinal dystrophies and provide a proof of concept for future clinical approximations. Full article

Cancer is the second leading cause of death worldwide, requiring more effective treatments. By-products from the white shrimp (Penaeus vannamei) are a promising source of bioactive compounds. Compounds with antiproliferative activity were isolated and identified in exoskeleton and cephalothorax extracts. The hexane extract of the exoskeleton reduced the viability of Human Prostate Carcinoma cell line (22Rv1) to 40.6% without toxicity in Adult Retinal Pigment Epithelium-19 (ARPE-19). Among the 19 fractions obtained, H3 reduced cell viability to 20.78%. Spectroscopic analysis identified bis(2-ethylhexyl) terephthalate, neoxanthin, and violaxanthin. Fluorescence microscopy showed morphological alterations. These findings demonstrate in vitro antiproliferative activity of compounds derived from shrimp by-products and support further studies to elucidate their mechanisms of action and evaluate their potential relevance in cancer prevention or therapeutic research. Full article

Experimental autoimmune uveitis (EAU) in rats is a pivotal model for understanding the immunological mechanisms of human uveitis and developing therapies. In humans, optical coherence tomography (OCT) allows for the in vivo detection of characteristic findings in active uveitis, as well as sequelae of inflammation. The objective of this study was to correlate OCT findings in patients with uveitis with retinal histologies from two rat models of EAU caused by T cells with different autoantigen specificities and well-known underlying immunological pathomechanisms. Patients with various noninfectious uveitis subtypes underwent imaging using an ultra-widefield swept source or conventional OCT. Histological cryosections from rat eyes with experimental autoimmune uveitis were stained for T cell and/or macrophage markers. Typical human OCT findings were reproduced in the experimental animal model. Hyperreflective signals observed on OCT corresponded to lymphocyte infiltration in histological sections. This infiltration was typically found as vasculitis in the perivascular regions and snowballs in the posterior hyaloid. There was lymphocyte and macrophage infiltration of the retina through the retinal vessels and the retinal pigment epithelium. Comparing in vivo OCT imaging of human uveitis with corresponding histologies from rat models improves our understanding of the type of inflammation, extent of tissue destruction, and immunopathogenesis. Full article

Fucoidans are natural compounds that exhibit bioactivity against age-related macular degeneration (AMD), the leading cause of central vision loss in industrialized nations. Pathological factors like oxidative stress and lipid peroxidation play vital roles in AMD pathogenesis. Lipid-induced alterations in the retinal pigment epithelium (RPE) contribute to AMD development. In this study, a commercial fucoidan from Fucus vesiculosus (FVs) was tested for its activity regarding lipid-peroxidation-related effects. The human RPE cell line ARPE-19, primary porcine RPE, and RPE/choroid explants were stimulated with erastin, acting as an inducer of lipid peroxidation, and treated with fucoidan. Effects on cell viability (tetrazolium bromide (MTT) or calcein staining), vascular endothelial growth factor (VEGF) and interleukin 8 (IL8) secretion (ELISA), reactive oxygen species (ROS), protein expression (glutathione peroxidase 4 (GPX4), CD59, and retinoid isomerohydrolase (RPE65), analyzed via Western blot), and gene expression (RT-qPCR) were investigated. FVs showed protective effects against erastin-induced reduction in viability (with a 12.7% increase in viability compared to erastin), RPE65 expression (with a 4.2-fold increase compared to erastin), and GPX4 expression (with a 2.3-fold increase compared to erastin) in primary RPE. Erastin-induced VEGF secretion was attenuated by FVs in ARPE-19 and primary RPE (with an up to 1.7-fold reduction compared to erastin). Elevated IL8 levels were reduced by FV treatment in primary RPE (with a 9.1-fold reduction compared to erastin). Induced VEGF in RPE/choroid explants was reduced by FVs (with an up to 2.9-fold reduction compared to erastin), and this reduction was correlated with slight improvements in viability. In conclusion, FVs exerted protective effects against lipid-induced stress. This study reveals further effects of fucoidans against AMD-related pathologies. Full article

Background/Objectives: Hydroxychloroquine (HCQ) is widely used in the treatment of autoimmune rheumatologic diseases due to its immunomodulatory and anti-inflammatory properties. However, long-term HCQ therapy carries a risk of irreversible retinal toxicity caused by drug accumulation in the retinal pigment epithelium. The early identification of preclinical retinal changes is essential to prevent permanent visual impairment. Optical coherence tomography (OCT) and OCT-angiography (OCT-A) have emerged as key imaging modalities for the detection of structural and microvascular biomarkers of HCQ retinopathy. A narrative review of the literature was conducted using the PubMed database, focusing on studies published between January 2017 and February 2025. Search terms included “hydroxychloroquine” and “optical coherence tomography.” Eligible studies evaluated HCQ-related retinal toxicity using OCT and/or OCT-A in human subjects. Data were extracted regarding study population characteristics, treatment duration, cumulative HCQ dose, daily dose normalized to real body weight, and reported imaging findings. Results: We identified 223 scientific papers of which 88 studies met the inclusion criteria. Structural OCT parameters—particularly alterations in the ellipsoid zone, outer nuclear layer, and retinal pigment epithelium—were consistently associated with early HCQ toxicity, often preceding functional impairment. OCT-A studies demonstrated microvascular alterations, including reduced vessel density and foveal avascular zone enlargement, though interpretation may be confounded by underlying autoimmune-disease-related vasculopathy. Conclusions: HCQ retinopathy is a potentially vision-threatening condition associated with the cumulative dose, treatment duration, and patient-specific risk factors. OCT and OCT-A provide complementary structural and vascular biomarkers that aid in the detection of subclinical retinal toxicity. The integration of quantitative and automated OCT-derived metrics may improve screening strategies, facilitate early diagnosis, and support personalized care in patients receiving long-term HCQ therapy. Full article

Age-related macular degeneration (AMD) is driven in part by the accumulation of reactive metabolites like glyoxal (GO), which induces retinal pigment epithelium (RPE) degeneration. Here, we demonstrate that GO triggers ferroptosis in human ARPE-19 cells, as characterized by iron-dependent lipid peroxidation, glutathione depletion, and reactive oxygen species (ROS) accumulation. This ferroptotic cell death is coupled with profound mitochondrial dysfunction, featuring network fragmentation and the downregulation of the key regulators MFN2, PGC-1α, and SIRT1. We identify hepatoma-derived growth factor (HDGF) as a potent protector against GO-induced damage. HDGF operates through a dual mechanism: it activates the p38 MAPK/AKT and SIRT1/PGC-1α axes to restore mitochondrial biogenesis and homeostasis, while concurrently enhancing the glutathione/GPX4 antioxidant system to suppress ferroptosis. This cytoprotective action is mediated via the PGC-1α/Nrf2 pathway, which integrates the enhancement of antioxidant defenses with the preservation of mitochondrial integrity. Our findings establish HDGF as a novel therapeutic agent for AMD, uniquely capable of concurrently targeting the interconnected pathways of ferroptosis and mitochondrial dysfunction, thereby addressing a critical unmet need in retinal disease treatment. Full article

Pathogenic variants in Crumbs homolog 1 (CRB1) cause a wide range of severe ocular diseases, most commonly Leber congenital amaurosis and other forms of adult-onset macular dystrophy that lead to vision loss. Despite this broad clinical spectrum, the expression and function of CRB1 in retinal cells remains underexplored. In this study, we show a comprehensive characterization of CRB1 isoforms in several human retinal models like retinal organoids. Although CRB1 is predominantly expressed in photoreceptors and Müller glial cells, we also detected its expression in the human retinal pigment epithelium (RPE). Moreover, we observed defined expression patterns of CRB1 isoforms depending on the maturation stage of retinal cells, suggesting a role for this protein in development and differentiation. In this context, the less abundant and less studied isoform CRB1-C was the most highly expressed in early undifferentiated stages of photoreceptors and in RPE. Additionally, clinical and genetic evaluation of a cohort of 25 probands carrying pathogenic CRB1 variants allowed us to propose a genotype–phenotype correlation between isoforms involvement and disease severity, and to the identification of four novel pathogenic variants: p.Met70ArgfsTer17, p.Cys136Phe, p.Cys248Ser and p.Gln1094Ter. Collectively, our data elucidate previously undescribed expression patterns of CRB1 isoforms during retinal cell differentiation and highlight key aspects of CRB1-associated inherited retinal dystrophies. Full article

To address the shortcomings of existing anti-VEGF monotherapy in neovascular age-related macular degeneration (nAMD), we investigated the therapeutic capabilities of exosomes obtained from human induced pluripotent stem cell (hiPSC)-derived retinal organoids in a mouse model of laser-induced choroidal neovascularization (CNV). To evaluate Retinal Organoid-derived exosome (RO-Exo) distribution after intravitreal (IVT) injection, calcein-labeled RO-Exo was observed using confocal microscopy. CNV was induced in C57BL/6 J mice by laser photocoagulation. RO-Exo was isolated from retinal organoids (differentiation days 55–65) and injected 5 days post-laser. Therapeutic efficacy was evaluated on day 12. Vascular leakage and CNV size were assessed by angiography and CD31 immunostaining. We also examined HIF-1α/VEGF-A expression (Western blotting), Retinal Pigment Epithelium (RPE) integrity markers (immunofluorescence staining for α-SMA, fibronectin, and ZO-1), and the activation of the Mitogen-Activated Protein Kinase (MAPK) pathway (phospho-ERK, -p38, -JNK) in CNV lesions. After IVT injection, RO-Exo migrated to the RPE layer, showing high retinotropic distribution. In the CNV model, RO-Exo significantly reduced vascular leakage and CNV size, with greater suppression of HIF-1α and VEGFA expression than aflibercept, the standard-of-care anti-VEGF drug. CD31-positive vasculature was decreased, accompanied by downregulation of fibronectin (a fibrotic marker) and restoration of RPE hexagonality and integrity. Furthermore, RO-Exo inhibited the activation of ERK, P38, and JNK in CNV lesions. Our study results demonstrate that RO-Exo exhibits multi-target therapeutic effects—including anti-angiogenic, anti-fibrotic, and neuroprotective actions—offering a promising alternative to conventional anti-VEGF therapy for nAMD. Full article

American Staffordshire Terriers (ASTs) with a c.296G>A variant in ARSG develop progressive ataxia, cerebellar atrophy, and neuronal accumulation of autofluorescent storage material. Human subjects with ARSG variants exhibit hearing loss and rod–cone dystrophy without apparent other neurological involvement and arsg knockout mice exhibit progressive ataxia, lysosomal storage, and photoreceptor loss. Owners of 8 of 11 affected ASTs evaluated for the ARSG risk variant reported observing visual impairment in their dogs, suggesting that the canine disease may involve retinal dysfunction consistent with human subjects and mice with ARSG variants. To assess whether this might be the case, electroretinography was performed on four affected and three unaffected ASTs. Three affected dogs that were exhibiting signs of ataxia had attenuated electroretinogram (ERG) amplitudes indicative of rod and cone photoreceptor dysfunction, while ERG responses were not attenuated in a younger dog that had not yet shown signs of ataxia or visual impairment. Autofluorescent inclusions were observed in the retinal pigment epithelium and retinal ganglion cell layer of two affected dogs that were euthanized due to neurological disease progression. The results from these cases indicate that standardized electroretinography can be used to detect retinal dysfunction in dogs with the ARSG-related disorder and in other disorders in which dogs exhibit apparent impairment in visually mediated behavior. Full article

Oxidative stress destabilizes microRNA homeostasis in the retinal pigment epithelium (RPE), driving apoptosis and the epithelial-to-mesenchymal transition, which contribute to age-related macular degeneration. We investigated whether Quantum Molecular Resonance (QMR^®) electrostimulation, alone or combined with Patient Blood-Derived (PBD) secretoma, can reprogram the RPE miRNome and mitigate stress-induced damage. Human ARPE-19 cells were exposed to tert-butyl-hydroperoxide and treated with QMR^®, PBD secretome, or their combination. The deep sequencing of small RNAs at 24 h and 72 h, followed by differential expression and pathway enrichment analyses, delineated treatment-driven miRNA signatures. Oxidative stress deregulated > 50 miRNAs, enriching pro-apoptotic, fibrotic, and inflammatory pathways. QMR^® restored roughly 40% of these miRNAs and upregulated additional cytoprotective species such as miR-590-3p, a known regulator of the NF-κB and NLRP3 pathways according to validated target databases. While these observations suggest the potential involvement of inflammatory and stress-related cascades, functional assays will be required to directly confirm such effects. Secretome treatment preferentially increased anti-inflammatory miR-146a-5p and regenerative miR-204-5p while suppressing pro-fibrotic let-7f-5p. Combined QMR^® + secretome triggered the broadest miRNA response, normalizing over two-thirds of stress-altered miRNAs. These changes are predicted to influence antioxidant, anti-apoptotic, and anti-fibrotic pathways, although they did not translate into additional short-term cytoprotection compared with QMR^® alone. These data indicate that QMR^® and PBD secretome modulate complementary miRNA programs that converge on stress response networks. This broader molecular reprogramming may reflect regulatory complementarity, but functional validation is needed to determine whether it provides benefits beyond those observed with QMR^® alone. These findings offer molecular insights into potential non-invasive, cell-free strategies for retinal degeneration, although in vivo validation will be required before any clinical translation to Age-Related Macular Degeneration (AMD) therapy. Full article

Retinal Pigment Epithelium (RPE), a component of the blood–retinal barrier, plays a pivotal role in maintaining retinal homeostasis and visual function. Dysfunction of the RPE is an early event that triggers photoreceptor death, in Age-related Macular Degeneration (AMD), a multifactorial disorder primarily caused by an imbalance between endogenous antioxidant defenses and reactive oxygen species production. Our in vitro study investigated the hormetic effects of curcumin in human RPE cells (ARPE-19), focusing on its capability to modulate two enzymes related to the onset of AMD: Sirtuin 1 (SIRT1), a NAD+-dependent deacetylase enzyme involved in cellular metabolism, aging, and stress response, and caspase-3, a crucial enzyme in programmed cell death. Curcumin exhibited classic hormetic doseresponses, with low concentrations (5–10 μM) providing cytoprotection while at high doses (≥20 μM) inducing toxicity. Under moderate oxidative stress, acetylated p53 was significantly reduced, indicating SIRT1 activation; curcumin 10 μM restored basal SIRT1 activity, while 5 µM did not. Both concentrations significantly decreased cleaved caspase-3 levels, demonstrating the anti-apoptotic effects of curcumin. Our results reveal curcumin’s hormetic mechanisms of RPE protection and emphasize the critical importance of dose optimization within the hormetic window for AMD therapeutic development. Full article

Replacement of the retinal pigment epithelium (RPE) is emerging as a promising approach to treat degenerative retinal diseases, including age-related macular degeneration and Stargardt disease, in which RPE function cannot otherwise be restored. Despite the limitations of existing treatments, advances in cell sourcing and surgical methods have enabled initial human trials of RPE transplantation, with early results indicating potential efficacy. This review comprehensively examines the evolution of RPE transplantation in recent decades, highlighting the advantages and limitations of different cell sources and delivery methods. Current clinical trial data are analyzed with a particular focus on immune rejection risks, surgical complications, and long-term safety. Despite encouraging safety profiles, achieving consistent and sustained visual improvement remains a challenge, as vision outcomes might be influenced by factors such as disease stage at intervention, transplantation site, number of cells transplanted, and duration of follow-up. Key challenges, such as cell or graft survival and integration with the host retina, are discussed in depth, as overcoming these obstacles is essential for achieving stable and effective RPE replacement. Future research directions, including innovations in biomaterials, molecular modification strategies, and personalized approaches, hold promise for enhancing the efficacy and durability of RPE transplantation for retinal disease. Full article

Geographic atrophy or late-stage dry age-related macular degeneration (AMD) is characterized by drusen deposition and progressive retinal pigment epithelium (RPE) degeneration, leading to irreversible vision loss. The formation of drusen leads to dyshomeostasis, oxidative stress, and irreversible damage to the RPE. In this study, we used an in vitro model of oxidized low-density lipoprotein (ox-LDL)-induced human RPE damage/death to investigate the mechanism through which a sterically hindered phenol antioxidant compound, PMC (2,2,5,7,8-pentamethyl-6-chromanol), protects the RPE against ox-LDL-induced damage. We show that PMC exerts its protective effect by preventing the upregulation of stress-responsive heme oxygenase-1 (HMOX1/HO-1) and NAD(P)H: quinone oxidoreductase (NQO1) at the mRNA and protein levels. This effect was due to PMC’s blockade of ROS generation, which in turn blocked nuclear translocation of the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor, ultimately preventing the upregulation of antioxidant response elements (AREs), including HMOX1 and NQO1. The key role of HO-1 was demonstrated when the protective effect of PMC was inhibited by the knockdown of HMOX1. Additionally, PMC treatment under different experimental conditions and at different time points revealed that the continuous presence of PMC is required for the optimal protection against ox-LDL-induced cytotoxicity, defining the cellular pharmacokinetics of this molecule. Our data demonstrate the involvement of a key antioxidant pathway through which PMC mitigates the oxidative stress induced by ox-LDL and provides a potential therapeutic strategy for suppressing RPE degeneration/damage during AMD progression. Full article