Mast cells promote choroidal neovascularization in a model of age-related macular degeneration.

'Wet' age-related macular degeneration (AMD) is characterized by pathologic choroidal neovascularization (CNV) that destroys central vision. Abundant evidence points to inflammation and immune cell dysfunction in the progression of CNV in AMD. Mast cells are resident immune cells that control the inflammatory response. Mast cells accumulate and degranulate in the choroid of patients with AMD, suggesting they play a role in CNV. Activated mast cells secrete various biologically active mediators, including inflammatory cytokines and proteolytic enzymes such as tryptase. We investigated the role of mast cells in AMD using a model of CNV. Conditioned media from activated mast cells exerts proangiogenic effects on choroidal endothelial cells and choroidal explants. Laser-induced CNV in vivo was markedly attenuated in mice genetically depleted of mast cells (KitW-sh/W-sh) and in wild-type mice treated with mast cell stabilizer, ketotifen fumarate. Tryptase was found to elicit pronounced choroidal endothelial cell sprouting, migration and tubulogenesis; while tryptase inhibition diminished CNV. Transcriptomic analysis of laser-treated RPE/choroid complex revealed collagen catabolism and extracellular matrix (ECM) reorganization as significant events correlated in clusters of mast cell activation. Consistent with these analyses, compared to wildtype mice choroids of laser-treated mast cell-deficient mice displayed less ECM remodelling evaluated using collagen hybridizing peptide tissue binding. Findings herein provide strong support for mast cells as key players in the progression of pathologic choroidal angiogenesis and as potential therapeutic targets to prevent pathological neovascularization in 'wet' AMD.

YTHDF1-regulated ALOX5 in retinal pigment epithelial cells under hypoxia enhances VEGF expression and promotes viability, migration, and angiogenesis of vascular endothelial cells.

Upregulation of vascular endothelial growth factor (VEGF) and enhanced angiogenesis have been implicated in the severe progression of age-related macular degeneration (AMD). Abnormal arachidonate 5-lipoxygenase (ALOX5) is associated with AMD pathogenesis. However, no reports have shown the causal role of ALOX5 in angiogenesis during AMD. In the present study, ARPE-19 cells were exposed to hypoxia, an inducer of VEGF expression. Potential proteins implicated in AMD progression were predicted using bioinformatics. RNA affinity antisense purification-mass spectrometry (RAP-MS) was applied to identify the binding proteins of ALOX5 3'UTR. Expression of ALOX5 and YTH N6-methyladenosine RNA-binding protein 1 (YTHDF1) was detected by qRT-PCR and western blotting. VEGF expression and secretion were assessed by immunofluorescence and ELISA, respectively. The chicken embryo chorioallantoic membrane (CAM) was used to analyze the effect of ALOX5 on angiogenesis. RNA stability was assayed using the Actinomycin D assay. The results show that hypoxia promoted cell growth and increased VEGF expression in ARPE-19 cells. ALOX5 was associated with AMD progression, and hypoxia upregulated ALOX5 expression in ARPE-19 cells. ALOX5 silencing reduced VEGF expression induced by hypoxia in ARPE-19 cells. Moreover, the conditioned medium of ALOX5-silenced ARPE-19 cells could suppress the viability and migration of HUVECs and diminish angiogenesis in the CAM. Furthermore, YTHDF1 was validated to bind to ALOX5 3'UTR, and YTHDF1 promoted ALOX5 expression by elevating the stability of ALOX5 mRNA. In conclusion, our findings demonstrate that YTHDF1-regulated ALOX5 increases VEGF expression in hypoxia-exposed ARPE-19 cells and enhances the viability, migration, and angiogenesis of vascular endothelial cells.

Genome-wide association study of subfoveal choroidal thickness in a longitudinal cohort of older adults.

To identify genetic influences on subfoveal choroidal thickness of older adults using a genome-wide association study (GWAS). We recruited 300 participants from the population-based Korean Longitudinal Study on Health and Aging (KLoSHA) and Korean Longitudinal Study on Cognitive Aging and Dementia (KLOSCAD) cohort studies and 500 participants from the Bundang age-related macular degeneration (AMD) cohort study dataset. We conducted a GWAS on older adult populations in the KLoSHA and KLOSCAD cohorts. Single nucleotide polymorphisms (SNPs) associated with choroidal thickness were identified with P values < 1.0 × 10-4 in both the right and left eyes, followed by validation using the Bundang AMD cohort dataset. This association was further confirmed by a functional in vitro study using human umbilical vein endothelial cells (HUVECs). The ages of the cohort participants in the discovery and validation datasets were 73.5 ± 3.3 and 71.3 ± 7.9 years, respectively. In the discovery dataset, three SNPs (rs1916762, rs7587019, and rs13320098) were significantly associated with choroidal thickness in both eyes. This association was confirmed for rs1916762 (genotypes GG, GA, and AA) and rs7587019 (genotypes GG, GA, and AA), but not for rs13320098. The mean choroidal thickness decreased by 56.7 µm (AA, 73.8%) and 31.1 µm (GA, 85.6%) compared with that of the GG genotype of rs1916762, and by 55.4 µm (AA, 74.2%) and 28.2 µm (GA, 86.7%) compared with that of the GG genotype of rs7587019. The SNPs rs1916762 and rs7587019 were located close to the FAM124B gene near its cis-regulatory region. Moreover, FAM124B was highly expressed in vascular endothelial cells. In vitro HUVEC experiments showed that the inhibition of FAM124B was associated with decreased vascular endothelial proliferation, suggesting a potential mechanism of choroidal thinning. FAM124B was identified as a susceptibility gene affecting subfoveal choroidal thickness in older adults. This gene may be involved in mechanisms underlying retinal diseases associated with altered choroidal thickness, such as age-related macular degeneration.

Adaptive optics scanning laser ophthalmoscopy in a heterogenous cohort with Stargardt disease.

Image based cell-specific biomarkers will play an important role in monitoring treatment outcomes of novel therapies in patients with Stargardt (STGD1) disease and may provide information on the exact mechanism of retinal degeneration. This study reports retinal image features from conventional clinical imaging and from corresponding high-resolution imaging with a confocal adaptive optics scanning laser ophthalmoscope (AOSLO) in a heterogenous cohort of patients with Stargardt (STGD1) disease. This is a prospective observational study in which 16 participants with clinically and molecularly confirmed STGD1, and 7 healthy controls underwent clinical assessment and confocal AOSLO imaging. Clinical assessment included short-wavelength and near-infrared fundus autofluorescence, spectral-domain optical coherence tomography, and macular microperimetry. AOSLO images were acquired over a range of retinal eccentricities (0°-20°) and mapped to areas of interest from the clinical images. A regular photoreceptor mosaic was identified in areas of normal or near normal retinal structure on clinical images. Where clinical imaging indicated areas of retinal degeneration, the photoreceptor mosaic was disorganised and lacked unambiguous cones. Discrete hyper-reflective foci were identified in 9 participants with STGD1 within areas of retinal degeneration. A continuous RPE cell mosaic at the fovea was identified in one participant with an optical gap phenotype. The clinical heterogeneity observed in STGD1 is reflected in the findings on confocal AOSLO imaging.

A new texture-based labeling framework for hyper-reflective foci identification in retinal optical coherence tomography images.

An important abnormality in Optical Coherence Tomography (OCT) images is Hyper-Reflective Foci (HRF). This anomaly can be interpreted as a biomarker of serious retinal diseases such as Age-related Macular Degeneration (AMD) and Diabetic Macular Edema (DME) or the progression of disease from an early stage to a late one. In this paper, a new method is proposed for the identification of HRFs. The new method divides the OCT B-scan into patches and separately verifies each patch to determine whether or not the patch contains an HRF. The procedure of patch verification contains a texture-based framework which assigns appropriate labels according to intensity changes to each column and row. Then, a feature vector is extracted for each patch based on the assigned labels. The feature vectors are utilized in the training step of well-known classifiers like Support Vector Machine (SVM). Then, the classifiers are used to produce the labels for the test OCT images. The new method is evaluated on a public dataset including HRF labels. The experimental results show that the new method is capable of providing outstanding results in terms of speed and accuracy.

Hyperspectral retinal imaging in Alzheimer's disease and age-related macular degeneration: a review.

While Alzheimer's disease and other neurodegenerative diseases have traditionally been viewed as brain disorders, there is growing evidence indicating their manifestation in the eyes as well. The retina, being a developmental extension of the brain, represents the only part of the central nervous system that can be noninvasively imaged at a high spatial resolution. The discovery of the specific pathological hallmarks of Alzheimer's disease in the retina of patients holds great promise for disease diagnosis and monitoring, particularly in the early stages where disease progression can potentially be slowed. Among various retinal imaging methods, hyperspectral imaging has garnered significant attention in this field. It offers a label-free approach to detect disease biomarkers, making it especially valuable for large-scale population screening efforts. In this review, we discuss recent advances in the field and outline the current bottlenecks and enabling technologies that could propel this field toward clinical translation.

Serum-deprivation response of ARPE-19 cells; expression patterns relevant to age-related macular degeneration.

ARPE-19 cells are derived from adult human retinal pigment epithelium (RPE). The response of these cells to the stress of serum deprivation mimics some important processes relevant to age-related macular degeneration (AMD). Here we extend the characterization of this response using RNASeq and EGSEA gene set analysis of ARPE-19 cells over nine days of serum deprivation. This experiment confirmed the up-regulation of cholesterol and lipid-associated pathways that increase cholesterol levels in these cells. The gene expression analysis also identified other pathways relevant to AMD progression. There were significant changes in extracellular matrix gene expression, notably a switch from expression of collagen IV, a key component of Bruch's membrane (part of the blood-retina barrier), to expression of a fibrosis-like collagen type I matrix. Changes in the expression profile of the extracellular matrix led to the discovery that amelotin is induced in AMD and is associated with the development of the calcium deposits seen in late-stage geographic atrophy. The transcriptional profiles of other pathways, including inflammation, complement, and coagulation, were also modified, consistent with immune response patterns seen in AMD. As previously noted, the cells resist apoptosis and autophagy but instead initiate a gene expression pattern characteristic of senescence, consistent with the maintenance of barrier function even as other aspects of RPE function are compromised. Other differentially regulated genes were identified that open new avenues for investigation. Our results suggest that ARPE-19 cells maintain significant stress responses characteristic of native RPE that are informative for AMD. As such, they provide a convenient system for discovery and for testing potential therapeutic interventions.

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

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

Salidroside alleviates ferroptosis in FAC-induced Age-related macular degeneration models by activating Nrf2/SLC7A11/GPX4 axis.

INTRODUCTION: Age-related macular degeneration (AMD) is a significant contributor to irreversible impairment in visual capability, particularly in its non-neovascular (dry) form. Ferroptosis, an emerging form of programmed necrosis, involves generating lipid peroxidation (LOS) through free iron and reactive oxygen species (ROS). Salidroside, a glycoside from Rhodiola rosea, known for anti-inflammatory and antioxidant properties. The research aim was exploring whether ferroptosis exists in dry AMD pathogenesis and elucidate salidroside's protective mechanisms against ferroptosis in AMD murine models and ARPE-19 cells. METHODS: ARPE-19 cells were treated with varying concentrations of ferrous ammonium citrate (FAC) and salidroside. In an in vivo model, C57BL/6 mice were administered intraperitoneal injections of salidroside for 7 consecutive days, followed by an intravitreal injection (IVT) of FAC. After 7 days, the eyeballs were harvested for subsequent analyses. Ferroptosis markers were assessed using western blotting, immunofluorescence staining, and flow cytometry. To further elucidate the modulatory role of Nrf2 in ferroptosis, ARPE-19 cells were transfected with si-Nrf2. RESULTS: In vitro, FAC-treated ARPE-19 cells exhibited reduced viability, decreased mitochondrial membrane potential (MMP), and accumulation of iron and lipid peroxidation (LOS) products. In vivo, FAC administration by IVT led to outer nuclear layer thinning and compromised tight junctions in RPE cells. The GPX4, Nrf2, and SLC7A11 expressions were downregulated both in vitro and in vivo. Salidroside upregulated Nrf2 and ameliorated these outcomes, but its effects were attenuated in ARPE-19 cells transfected with si-Nrf2. CONCLUSION: Our study establishes that FAC induces RPE cell ferroptosis within dry AMD, and salidroside exerts therapeutic effects by triggering Nrf2/SLC7A11/GPX4 signaling axis.

The Impact of ARMS2 (rs10490924), VEGFA (rs3024997), TNFRSF1B (rs1061622), TNFRSF1A (rs4149576), and IL1B1 (rs1143623) Polymorphisms and Serum Levels on Age-Related Macular Degeneration Development and Therapeutic Responses.

Age-related macular degeneration (AMD) is a major global health problem as it is the leading cause of irreversible loss of central vision in the aging population. Anti-vascular endothelial growth factor (anti-VEGF) therapies are effective but do not respond optimally in all patients. This study investigates the genetic factors associated with susceptibility to AMD and response to treatment, focusing on key polymorphisms in the ARMS2 (rs10490924), IL1B1 (rs1143623), TNFRSF1B (rs1061622), TNFRSF1A (rs4149576), VEGFA (rs3024997), ARMS2, IL1B1, TNFRSF1B, TNFRSF1A, and VEGFA serum levels in AMD development and treatment efficacy. This study examined the associations of specific genetic polymorphisms and serum protein levels with exudative and early AMD and the response to anti-VEGF treatment. The AA genotype of VEGFA (rs3024997) was significantly associated with a 20-fold reduction in the odds of exudative AMD compared to the GG + GA genotypes. Conversely, the TT genotype of ARMS2 (rs10490924) was linked to a 4.2-fold increase in the odds of exudative AMD compared to GG + GT genotypes. In females, each T allele of ARMS2 increased the odds by 2.3-fold, while in males, the TT genotype was associated with a 5-fold increase. Lower serum IL1B levels were observed in the exudative AMD group compared to the controls. Early AMD patients had higher serum TNFRSF1B levels than controls, particularly those with the GG genotype of TNFRSF1B rs1061622. Exudative AMD patients with the CC genotype of TNFRSF1A rs4149576 had lower serum TNFRSF1A levels compared to the controls. Visual acuity (VA) analysis showed that non-responders had better baseline VA than responders but experienced decreased VA after treatment, whereas responders showed improvement. Central retinal thickness (CRT) reduced significantly in responders after treatment and was lower in responders compared to non-responders after treatment. The T allele of TNFRSF1B rs1061622 was associated with a better response to anti-VEGF treatment under both dominant and additive genetic models. These findings highlight significant genetic and biochemical markers associated with AMD and treatment response. This study found that the VEGFA rs3024997 AA genotype reduces the odds of exudative AMD, while the ARMS2 rs10490924 TT genotype increases it. Lower serum IL1B levels and variations in TNFRSF1B and TNFRSF1A levels were linked to AMD. The TNFRSF1B rs1061622 T allele was associated with better anti-VEGF treatment response. These markers could potentially guide risk assessment and personalized treatment for AMD.

Differential Expression of Mitogen-Activated Protein Kinase Signaling Pathways in the Human Choroid-Retinal Pigment Epithelial Complex Indicates Regional Predisposition to Disease.

The retina is composed of neuronal layers that include several types of interneurons and photoreceptor cells, and separate underlying retinal pigment epithelium (RPE), Bruch's membrane, and choroid. Different regions of the human retina include the fovea, macula, and periphery, which have unique physiological functions and anatomical features. These regions are also unique in their protein expression, and corresponding cellular and molecular responses to physiological and pathophysiological stimuli. Skeie and Mahajan analyzed regional protein expression in the human choroid-RPE complex. Mitogen-Activated Protein Kinase (MAPK) signaling pathways have been implicated in responses to stimuli such as oxidative stress and inflammation, which are critical factors in retina diseases including age-related macular degeneration. We, therefore, analyzed the Skeie and Mahajan, 2014, dataset for regional differences in the expression of MAPK-related proteins and discussed the potential implications in retinal diseases presenting with regional signs and symptoms. Regional protein expression data from the Skeie and Mahajan, 2014, study were analyzed for members of signaling networks involving MAPK and MAPK-related proteins, categorized by specific MAPK cascades, such as p38, ERK1/2, and JNK1/2, both upstream or downstream of the respective MAPK and MAPK-related proteins. We were able to identify 207 MAPK and MAPK-related proteins, 187 of which belonging to specific MAPK cascades. A total of 31 of these had been identified in the retina with two proteins, DLG2 and FLG downstream, and the other 29 upstream, of MAPK proteins. Our findings provide evidence for potential molecular substrates of retina region-specific disease manifestation and potential new targets for therapeutics development.

Crocin Protects the 661W Murine Photoreceptor Cell Line against the Toxic Effects of All-Trans-Retinal.

Age-related macular degeneration (AMD) is a common disease contributing to vision loss in the elderly. All-trans-retinal (atRAL) is a retinoid in the retina, and its abnormal accumulation exhibits toxicity to the retina and promotes oxidative stress-induced photoreceptor degeneration, which plays a crucial role in AMD progression. Crocin is a natural product extracted from saffron, which displays significant antioxidant and anti-inflammatory effects. The present study elucidates the protective effects of crocin on photoreceptor cell damage by atRAL and its potential mechanisms. The results revealed that crocin significantly attenuated cytotoxicity by repressing oxidative stress, mitochondrial injury, and DNA damage in atRAL-loaded photoreceptor cells. Moreover, crocin visibly inhibited DNA damage-induced apoptosis and gasdermin E (GSDME)-mediated pyroptosis in photoreceptor cells after exposure to atRAL. It was also observed that crocin distinctly prevented an increase in Fe2+ levels and lipid peroxidation caused by atRAL via suppressing the Kelch-like ECH-associated protein 1 (KEAP1)/nuclear factor-erythroid 2-related factor 2 (NRF2)/heme oxygenase-1 (HO-1) signaling pathway, thereby ameliorating photoreceptor cell ferroptosis. In short, these findings provide new insights that crocin mitigates atRAL-induced toxicity to photoreceptor cells by inhibiting oxidative stress, apoptosis, pyroptosis, and ferroptosis.

Deficient RPE mitochondrial energetics leads to subretinal fibrosis in age-related neovascular macular degeneration.

Subretinal fibrosis permanently impairs the vision of patients with neovascular age-related macular degeneration. Despite emerging evidence revealing the association between disturbed metabolism in retinal pigment epithelium (RPE) and subretinal fibrosis, the underlying mechanism remains unclear. In the present study, single-cell RNA sequencing revealed, prior to subretinal fibrosis, genes in mitochondrial fatty acid oxidation are downregulated in the RPE lacking very low-density lipoprotein receptor (VLDLR), especially the rate-limiting enzyme carnitine palmitoyltransferase 1A (CPT1A). We found that overexpression of CPT1A in the RPE of Vldlr-/- mice suppresses epithelial-to-mesenchymal transition and fibrosis. Mechanistically, TGFß2 induces fibrosis by activating a Warburg-like effect, i.e. increased glycolysis and decreased mitochondrial respiration through ERK-dependent CPT1A degradation. Moreover, VLDLR blocks the formation of the TGFß receptor I/II complex by interacting with unglycosylated TGFß receptor II. In conclusion, VLDLR suppresses fibrosis by attenuating TGFß2-induced metabolic reprogramming, and CPT1A is a potential target for treating subretinal fibrosis.

Quantitative comparison of automated OCT and conventional FAF-based geographic atrophy measurements in the phase 3 OAKS/DERBY trials.

With the approval of the first two substances for the treatment of geographic atrophy (GA) secondary to age-related macular degeneration (AMD), a standardized monitoring of patients treated with complement inhibitors in clinical practice is needed. Optical coherence tomography (OCT) provides high-resolution access to the retinal pigment epithelium (RPE) and neurosensory layers, such as the ellipsoid zone (EZ), which further enhances the understanding of disease progression and therapeutic effects in GA compared to conventional fundus autofluorescence (FAF). In addition, artificial intelligence-based methodology allows the identification and quantification of GA-related pathology on OCT in an objective and standardized manner. The purpose of this study was to comprehensively evaluate automated OCT monitoring for GA compared to reading center-based manual FAF measurements in the largest successful phase 3 clinical trial data of complement inhibitor therapy to date. Automated OCT analysis of RPE loss showed a high and consistent correlation to manual GA measurements on conventional FAF. EZ loss on OCT was generally larger than areas of RPE loss, supporting the hypothesis that EZ loss exceeds underlying RPE loss as a fundamental pathophysiology in GA progression. Automated OCT analysis is well suited to monitor disease progression in GA patients treated in clinical practice and clinical trials.

Generalizable Deep Learning for the Detection of Incomplete and Complete Retinal Pigment Epithelium and Outer Retinal Atrophy: A MACUSTAR Report.

Purpose: The purpose of this study was to develop a deep learning algorithm for detecting and quantifying incomplete retinal pigment epithelium and outer retinal atrophy (iRORA) and complete retinal pigment epithelium and outer retinal atrophy (cRORA) in optical coherence tomography (OCT) that generalizes well to data from different devices and to validate in an intermediate age-related macular degeneration (iAMD) cohort. Methods: The algorithm comprised a domain adaptation (DA) model, promoting generalization across devices, and a segmentation model for detecting granular biomarkers defining iRORA/cRORA, which are combined into iRORA/cRORA segmentations. Manual annotations of iRORA/cRORA in OCTs from different devices in the MACUSTAR study (168 patients with iAMD) were compared to the algorithm's output. Eye level classification metrics included sensitivity, specificity, and quadratic weighted Cohen's κ score (κw). Segmentation performance was assessed quantitatively using Bland-Altman plots and qualitatively. Results: For ZEISS OCTs, sensitivity and specificity for iRORA/cRORA classification were 38.5% and 93.1%, respectively, and 60.0% and 96.4% for cRORA. For Spectralis OCTs, these were 84.0% and 93.7% for iRORA/cRORA, and 62.5% and 97.4% for cRORA. The κw scores for 3-way classification (none, iRORA, and cRORA) were 0.37 and 0.73 for ZEISS and Spectralis, respectively. Removing DA reduced κw from 0.73 to 0.63 for Spectralis. Conclusions: The DA-enabled iRORA/cRORA segmentation algorithm showed superior consistency compared to human annotations, and good generalization across OCT devices. Translational Relevance: The application of this algorithm may help toward precise and automated tracking of iAMD-related lesion changes, which is crucial in clinical settings and multicenter longitudinal studies on iAMD.

A Novel Artificial Intelligence-Based Classification of Highly Myopic Eyes Based on Visual Function and Fundus Features.

Purpose: To develop a novel classification of highly myopic eyes using artificial intelligence (AI) and investigate its relationship with contrast sensitivity function (CSF) and fundus features. Methods: We enrolled 616 highly myopic eyes of 616 patients. CSF was measured using the quantitative CSF method. Myopic macular degeneration (MMD) was graded according to the International META-PM Classification. Thickness of the macula and peripapillary retinal nerve fiber layer (p-RNFL) were assessed by fundus photography and optical coherence tomography, respectively. Classification was performed by combining CSF and fundus features with principal component analysis and k-means clustering. Results: With 83.35% total variance explained, highly myopic eyes were classified into four AI categories. The percentages of AI categories 1 to 4 were 14.9%, 37.5%, 36.2%, and 11.4%, respectively. Contrast acuity of the eyes in AI category 1 was the highest, which decreased by half in AI category 2. For AI categories 2 to 4, every increase in category led to a decrease of 0.23 logarithm of the minimum angle of resolution in contrast acuity. Compared with those in AI category 1, eyes in AI category 2 presented a higher percentage of MMD2 and thinner temporal p-RNFL. Eyes in AI categories 3 and 4 presented significantly higher percentage of MMD ≥ 3, thinner nasal macular thickness and p-RNFL (P < 0.05). Multivariate regression showed AI category 4 had higher MMD grades and thinner macular compared with AI category 3. Conclusions: We proposed an AI-based classification of highly myopic eyes with clear relevance to visual function and fundus features. Translational Relevance: This classification helps to discover the early hidden visual deficits of highly myopic patients, becoming a useful tool to evaluate the disease comprehensively.

Metformin Alleviates Inflammation and Induces Mitophagy in Human Retinal Pigment Epithelium Cells Suffering from Mitochondrial Damage.

Mitochondrial malfunction, excessive production of reactive oxygen species (ROS), deficient autophagy/mitophagy, and chronic inflammation are hallmarks of age-related macular degeneration (AMD). Metformin has been shown to activate mitophagy, alleviate inflammation, and lower the odds of developing AMD. Here, we explored the ability of metformin to activate mitophagy and alleviate inflammation in retinal pigment epithelium (RPE) cells. Human ARPE-19 cells were pre-treated with metformin for 1 h prior to exposure to antimycin A (10 µM), which induced mitochondrial damage. Cell viability, ROS production, and inflammatory cytokine production were measured, while autophagy/mitophagy proteins were studied using Western blotting and immunocytochemistry. Metformin pre-treatment reduced the levels of proinflammatory cytokines IL-6 and IL-8 to 42% and 65% compared to ARPE-19 cells exposed to antimycin A alone. Metformin reduced the accumulation of the autophagy substrate SQSTM1/p62 (43.9%) and the levels of LC3 I and II (51.6% and 48.6%, respectively) after antimycin A exposure. Metformin also increased the colocalization of LC3 with TOM20 1.5-fold, suggesting active mitophagy. Antimycin A exposure increased the production of mitochondrial ROS (226%), which was reduced by the metformin pre-treatment (84.5%). Collectively, metformin showed anti-inflammatory and antioxidative potential with mitophagy induction in human RPE cells suffering from mitochondrial damage.

Structural and functional characterization of the nucleotide-binding domains of ABCA4 and their role in Stargardt disease.

ABCA4 is an ATP-binding cassette (ABC) transporter that prevents the buildup of toxic retinoid compounds by facilitating the transport of N-retinylidene-phosphatidylethanolamine across membranes of rod and cone photoreceptor cells. Over 1500 missense mutations in ABCA4, many in the nucleotide-binding domains (NBDs), have been genetically linked to Stargardt disease. Here, we show by cryo-EM that ABCA4 is converted from an open outward conformation to a closed conformation upon the binding of adenylyl-imidodiphosphate. Structural information and biochemical studies were used to further define the role of the NBDs in the functional properties of ABCA4 and the mechanisms by which mutations lead to the loss in activity. We show that ATPase activity in both NBDs is required for the functional activity of ABCA4. Mutations in Walker A asparagine residues cause a severe reduction in substrate-activated ATPase activity due to the loss in polar interactions with residues within the D-loops of the opposing NBD. The structural basis for how disease mutations in other NBD residues, including the R1108C, R2077W, R2107H, and L2027F, affect the structure and function of ABCA4 is described. Collectively, our studies provide insight into the structure and function of ABCA4 and mechanisms underlying Stargardt disease.

VEGF and ELAVL1/HuR protein levels are increased in dry and wet AMD patients. A new tile in the pathophysiologic mechanisms underlying RPE degeneration?

Age-related macular degeneration (AMD) is a common retinal pathology characterized by degeneration of macula's retinal pigment epithelium (RPE) and photoreceptors, visual impairment, or loss. Compared to wet AMD, dry AMD is more common, but lacks cures; therefore, identification of new potential therapeutic targets and treatments is urgent. Increased oxidative stress and declining antioxidant, detoxifying systems contribute to the pathophysiologic mechanisms underlying AMD. The present work shows that the Embryonic Lethal Abnormal Vision-Like 1/Human antigen R (ELAVL1/HuR) and the Vascular Endothelial Growth Factor (VEGF) protein levels are higher in the RPE of both dry and wet AMD patients compared to healthy subjects. Moreover, increased HuR protein levels are detected in the retina, and especially in the RPE layer, of a dry AMD model, the nuclear factor erythroid 2-related factor 2 (Nrf2) / peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) double knock-out mouse. The crosstalk among Nrf2, HuR and VEGF has been also studied in ARPE-19 cells in basal and stressful conditions related to the AMD context (i.e., oxidative stress, autophagy impairment, Nrf2 deficit), offering new evidence of the mutual influence between Nrf2 and HuR, of the dependence of VEGF expression and secretion by these two factors, and of the increased susceptibility of cells to stressful conditions in Nrf2- or HuR-impaired contexts. Overall, this study shows evidence of the interplay among Nrf2, HuR and VEGF, essential factors for RPE homeostasis, and represents an additional piece in the understanding of the complex pathophysiologic mechanisms underlying AMD.

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

AIM: The aim of this study was to evaluate the potential protective effect of Qiju Granule in a rat model of age-related macular degeneration (AMD) and investigate the underlying mechanisms involved. METHODS: Rats were injected intravenously with 40 mg/kg of sodium iodate (SI) to induce a dry AMD model. The rats in the treatment group received three different doses of Qiju Granule once a day via gavage, while the rats in the control group were given an equal volume of physiological saline. On day 14 and day 28 following the intervention, various methods were employed to evaluate retinal function and structure, including electroretinography (ERG), optical coherence tomography (OCT), and histological examination. The expression of glial fibrillary acidic protein (GFAP), basic fibroblast growth factor (bFGF), brain-derived neurotrophic factor (BDNF), and ciliary neurotrophic factor (CNTF) was assessed via immunofluorescence. Beyond immunofluorescence, the mRNA levels of bFGF, BDNF, and CNTF were quantitatively determined using real-time polymerase chain reaction (qRT-PCR). RESULTS: Rats treated with Qiju Granule exhibited significant improvements in both retinal function and structure compared to the model group. The most noteworthy effects were observed at a high dose of Qiju Granule. Furthermore, the expression levels of bFGF, BDNF, and CNTF were significantly unregulated in the treated groups compared to the model group. CONCLUSIONS: Qiju Granule demonstrated a protective effect on the retina in the SI-induced rat model of AMD. The protective mechanism may be attributed to the upregulation of retinal neurotrophic factors expression.