Molecular mechanisms of subretinal fibrosis in age-related macular degeneration

Hyperreflective Foci Along the Retinal Pigment Epithelium Predict the Onset of Large Choroidal Hypertransmission Defects in Age-Related Macular Degeneration

PURPOSE

In eyes with intermediate age-related macular degeneration (iAMD), we separately quantified the hyperreflective foci (HRF) along the retinal pigment epithelium (rpeHRF) and the intraretinal HRF (iHRF) to determine if the location of the HRF predicted the progression from iAMD to the onset of large persistent choroidal hypertransmission defects (hyperTDs).

DESIGN

Post hoc subgroup cohort analysis of a prospective study.

METHODS

A retrospective analysis was performed on a prospective natural history database of eyes with AMD imaged using swept-source optical coherence tomography (SS-OCT). En face images derived from choroidal slabs positioned 64 to 400 µm beneath Bruch membrane were used with a semiautomated algorithm to identify and quantify hypotransmission defects (hypoTDs) attributable to either iHRF or rpeHRF within a 5-mm fovea-centered circle. iHRF were identified on corresponding B-scans as hyperreflective lesions within the neurosensory retina, and rpeHRF were identified as areas of retinal pigment epithelium thickening. Multivariable survival analysis was performed to determine if the area measurements of either iHRF or rpeHRF were more likely to predict the onset of the first large persistent hyperTD.

RESULTS

Of the 171 eyes with iAMD included in this study, 82 (48%) developed at least 1 large hyperTD during a median follow-up of 59.1 months. Univariable Cox regression analyses showed that rpeHRF area (P < .001), iHRF area (P = .003), and drusen volume (P < .001) were all significantly associated with the onset of the first large persistent hyperTD. However, a multivariable Cox regression model showed that only the rpeHRF area remained a significant predictor of disease progression (P < .001).

CONCLUSIONS

In iAMD eyes, the area of rpeHRF was more predictive of disease progression than either the drusen volume or iHRF, which suggests that these rpeHRF serve as harbingers of focal atrophy formation and may predict where hyperTDs form.

JAM-C prevents ocular fibrosis by suppressing the TAZ/KLF6 pathway

INTRODUCTION

Ocular fibrosis is one of the leading causes of irreversible visual impairment or blindness. Currently, there is no effective drug available for such diseases. Therefore, understanding the underlying mechanisms is a prerequisite for finding better therapeutic strategies.

OBJECTIVES

This study aims to investigate the role of the junctional adhesion molecule C (JAM-C) in ocular fibrosis.

METHODS

The protein levels of JAM-C were determined in the vitreous humor samples of patients with ocular fibrosis using ELISA. Jam-c genetic deletion mice and ocular fibrosis mouse models were generated to study the role of JAM-C in vivo. EMT, proliferation, migration, and gel contraction capacities in RPE cells were examined after JAM-C knockdown by siRNAs. RNA sequencing, co-IP, ChIP-qPCR, and luciferase reporter assay were performed to investigate the underlying mechanisms. Subretinal injection of adeno-associated virus, immunofluorescence, western blot were performed to evaluate the potential of JAM-C in preventing ocular fibrosis in different mouse models.

RESULTS

Markedly reduced JAM-C expression was found in patients with ocular fibrosis. Genetic deletion of Jam-c in mice exacerbated ocular fibrosis, and JAM-C knockdown triggered the EMT process in RPE cells. Mechanistically, we reveal that JAM-C inhibits ocular fibrosis by suppressing the nuclear localization and function of TAZ, which otherwise binds to KLF6 to promote its expression and activity to initiate the EMT cascade. Importantly, AAV-mediated JAM-C augmentation alleviated ocular fibrosis in different mouse models.

CONCLUSION

Our findings unveil a novel function of JAM-C in preventing ocular fibrosis by inhibiting the TAZ/KLF6 pathway, and suggest new therapeutic possibilities for the treatment of fibrotic diseases.

Artemisinin and Its Derivatives: Promising Therapeutic Agents for Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is a leading cause of visual impairment and blindness in older adults. Its pathogenesis involves multiple factors, including aging, environmental influences, genetic predisposition, oxidative stress, metabolic dysfunction, and immune dysregulation. Currently, AMD treatment focuses primarily on wet AMD, managed through repeated intravitreal injections of anti-vascular endothelial growth factor (VEGF) therapies. While anti-VEGF agents represent a major breakthrough in wet AMD care, repeated injections may lead to incomplete responses or resistance in some patients, and carry a risk of progressive fibrosis. Artemisinin (ART) and its derivatives, originally developed as antimalarial drugs, exhibit a broad spectrum of pleiotropic activities beyond their established use, including anti-inflammatory, anti-angiogenic, antioxidant, anti-fibrotic, mitochondrial regulatory, lipid metabolic, and immunosuppressive effects. These properties position ART as a promising therapeutic candidate for AMD. A growing interest in ART-based therapies for AMD has emerged in recent years, with numerous studies demonstrating their potential benefits. However, no comprehensive review has systematically summarized the specific roles of ART and its derivatives in AMD pathogenesis and treatment. This paper aims to fill the knowledge gap by synthesizing the therapeutic efficacy and molecular mechanisms of ART and its derivatives in AMD, thereby providing a foundation for future investigations.

Klotho attenuates epithelial‑mesenchymal transition of retinal pigment epithelial cells in subretinal fibrosis by suppressing the ERK1/2 and Wnt/β‑catenin signaling pathways

Retinal pigment epithelial (RPE) cells undergoing epithelial‑mesenchymal transition (EMT) are a key factor in promoting the progression of subretinal fibrosis. The klotho protein and gene exert anti‑fibrotic effects in multiple fibrotic diseases. However, the mechanisms involved in the role of klotho are unclear in subretinal fibrosis. The aim of the present study was to explore the effects of klotho on subretinal fibrosis induced by laser photocoagulation in mice and EMT induced by TGF‑β1 in RPE cells and the underlying molecular mechanisms. In vitro, klotho overexpression or knockdown was performed in ARPE‑19 cells (adult retinal Pigment Epithelial‑19), then TGF‑β1 treatment was applied. Using western blotting, expression of epithelial markers (zonula occludens‑1), mesenchymal signs (α‑smooth muscle actin, α‑SMA, N‑cadherin, N‑cad and collagen I), and the ERK1/2 and Wnt/β‑catenin signaling pathways were assessed. The proliferative ability of ARPE‑19 cells was examined by CCK‑8 and EdU test, and the migratory ability was examined by wound healing and Transwell assays. Furthermore, to explore the underlying molecular pathway of klotho overexpression, RNA‑sequencing (seq) was performed. In vivo, photocoagulation was used to induce subretinal fibrosis in mice, which occurs as a result of choroidal neovascularization (CNV), then recombinant mouse klotho protein was administered intravitreally. Upregulation of epithelial and downregulation of mesenchymal markers demonstrated that klotho overexpression prevented TGF‑β1‑induced EMT; klotho knockdown resulted in the opposite effects. Additionally, klotho overexpression suppressed cell proliferation and migration and attenuated ERK1/2 and Wnt/β‑catenin signaling activated by TGF‑β1. RNA‑seq results demonstrated that several signaling pathways, including cellular senescence and the TNF signaling pathway, were associated with anti‑fibrotic effects of klotho overexpression. In vivo, subretinal fibrotic areas were attenuated following klotho treatment in laser‑induced CNV lesions, as illustrated by immunofluorescence and Masson staining of the mouse eyes. Western blotting results that the protein levels of mesenchymal markers were significantly downregulated and those of epithelial markers were upregulated. In summary, the present study suggested that klotho may have therapeutic value in management of fibrotic vitreoretinal disorders such as subretinal fibrosis.

Subretinal fibrosis occurrence according to macular neovascularisation subtypes in neovascular age-related macular degeneration

PURPOSE

To assess subretinal fibrosis (SF) occurrence in neovascular age-related macular degeneration (nAMD), according to macular neovascularisation (MNV) subtypes.

METHODS

A Retrospective national multi centre cohort study included eyes with naive nAMD. Main outcome measures were, according to MNV subtypes, cumulative incidence for SF, risk factors, and best corrected visual acuity (BCVA) for 36 months.

RESULTS

Four hundred and twenty eyes were included. Cumulative incidence of SF was 34.3% at 1 year, 39.0% at 2 years and 50.6% at 3 years. In multivariable analysis, Type 2 and mixed type 1 and 2 MNV were associated (p < 0.001) with a more frequent and rapid development of SF (respectively 85.5% and 81.0% at 1 year, then 95.8% and 93.1% at 3 years) than Types 1 and 3 (respectively 11.3% and 3.6% at 1 year, then 22.9% and 12.7% at 3 years). In Type 2 and mixed type 1 and 2 MNV combined, at baseline a worse BCVA (p = 0.02) and a higher maximal subretinal hyperreflective material (SHRM) thickness (p = 0.005) were associated with SF development at 3 years. In Type 1 MNV, the presence at baseline of intraretinal fluid (IRF) (p = 0.007) or SHRM (p < 0.001) and a higher percentage of visits with IRF (p < 0.001) or with SHRM (p < 0.001) were associated with SF occurrence. For Type 3 MNV, only a higher percentage of visits with SHRM (p = 0.001) was associated with SF. Including all MNV subtypes, eyes with a worse BCVA at baseline were associated with SF development (p < 0.001). Conversely, presence of SF at 3 years was associated with a worse baseline BCVA (p < 0.001).

CONCLUSION

Occurrence of SF differs when considering apart MNV subtypes.

RNA methylation homeostasis in ocular diseases: All eyes on Me

RNA methylation is a pivotal epigenetic modification that adjusts various aspects of RNA biology, including nuclear transport, stability, and the efficiency of translation for specific RNA candidates. The methylation of RNA involves the addition of methyl groups to specific bases and can occur at different sites, resulting in distinct forms, such as N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), and 7-methylguanosine (m7G). Maintaining an optimal equilibrium of RNA methylation is crucial for fundamental cellular activities such as cell survival, proliferation, and migration. The balance of RNA methylation is linked to various pathophysiological conditions, including senescence, cancer development, stress responses, and blood vessel formation, all of which are pivotal for comprehending a spectrum of eye diseases. Recent findings have highlighted the significant role of diverse RNA methylation patterns in ophthalmological conditions such as age-related macular degeneration, diabetic retinopathy, cataracts, glaucoma, uveitis, retinoblastoma, uveal melanoma, thyroid eye disease, and myopia, which are critical for vision health. This thorough review endeavors to dissect the influence of RNA methylation on common and vision-impairing ocular disorders. It explores the nuanced roles that RNA methylation plays in key pathophysiological mechanisms, such as oxidative stress and angiogenesis, which are integral to the onset and progression of these diseases. By synthesizing the latest research, this review offers valuable insights into how RNA methylation could be harnessed for therapeutic interventions in the field of ophthalmology.

Preclinical Retinal Disease Models: Applications in Drug Development and Translational Research

Retinal models play a pivotal role in translational drug development, bridging preclinical research and therapeutic applications for both ocular and systemic diseases. This review highlights the retina as an ideal organ for studying advanced therapies, thanks to its immune privilege, vascular and neuronal networks, accessibility, and advanced imaging capabilities. Preclinical retinal disease models offer unparalleled insights into inflammation, angiogenesis, fibrosis, and hypoxia, utilizing clinically translatable bioimaging tools like fundoscopy, optical coherence tomography, confocal scanning laser ophthalmoscopy, fluorescein angiography, optokinetic tracking, and electroretinography. These models have driven innovations in anti-inflammatory, anti-angiogenic, and neuroprotective strategies, with broader implications for systemic diseases such as rheumatoid arthritis, Alzheimer's, and fibrosis-related conditions. By emphasizing the integration of the 3Rs principles and novel imaging modalities, this review highlights how retinal research not only enhances therapeutic precision but also minimizes ethical concerns, paving the way for more predictive and human-relevant approaches in drug development.

Subretinal fibrosis secondary to neovascular age-related macular degeneration: mechanisms and potential therapeutic targets

Subretinal fibrosis is the end-stage sequelae of neovascular age-related macular degeneration. It causes local damage to photoreceptors, retinal pigment epithelium, and choroidal vessels, which leads to permanent central vision loss of patients with neovascular age-related macular degeneration. The pathogenesis of subretinal fibrosis is complex, and the underlying mechanisms are largely unknown. Therefore, there are no effective treatment options. A thorough understanding of the pathogenesis of subretinal fibrosis and its related mechanisms is important to elucidate its complications and explore potential treatments. The current article reviews several aspects of subretinal fibrosis, including the current understanding on the relationship between neovascular age-related macular degeneration and subretinal fibrosis; multimodal imaging techniques for subretinal fibrosis; animal models for studying subretinal fibrosis; cellular and non-cellular constituents of subretinal fibrosis; pathophysiological mechanisms involved in subretinal fibrosis, such as aging, infiltration of macrophages, different sources of mesenchymal transition to myofibroblast, and activation of complement system and immune cells; and several key molecules and signaling pathways participating in the pathogenesis of subretinal fibrosis, such as vascular endothelial growth factor, connective tissue growth factor, fibroblast growth factor 2, platelet-derived growth factor and platelet-derived growth factor receptor-β, transforming growth factor-β signaling pathway, Wnt signaling pathway, and the axis of heat shock protein 70-Toll-like receptors 2/4-interleukin-10. This review will improve the understanding of the pathogenesis of subretinal fibrosis, allow the discovery of molecular targets, and explore potential treatments for the management of subretinal fibrosis.

Resveratrol Supplementation in Wet AMD: Association With Fewer Intravitreal Injections and Reduced Macular Fibrosis

Purpose

To evaluate the 2-year outcomes of resveratrol oral supplement given as an adjunctive treatment in patients with wet age-related macular degeneration (AMD) that were treated with intravitreal injections of aflibercept.

Patients and Methods

In our retrospective study, 50 treatment-naïve patients suffering from wet-AMD were included. They were assigned to two subgroups of 25 patients each. Every participant was treated according to "Pro Re Nata" protocol; 3 monthly intravitreal injections of 2.0 mg aflibercept were applied followed by injections according to need. The patients in the second group also consumed daily two tablets of resveratrol enriched oral supplement (60 mg of resveratrol in total). For 2 years, the patients were monthly assessed with best corrected visual acuity (BCVA) measurement, fundus autofluorescence, optical coherence tomography (OCT) scans and OCT-angiography. The main endpoints were the change of BCVA, the number of anti-VEGF injections, the change of central foveal thickness values, and the expansion or new development of fibrosis.

Results

Between the studied groups, no significant differences were detected in the baseline demographic and clinical data (p>0.05 for all). Over the 24-month study period, both BCVA and central foveal thickness values did not differ significantly between the two groups. As for the number of applied injections, they were significantly fewer in the group of patients that were treated with the resveratrol supplement (9.32±1.37 vs 7.40±1.88, p<0.001). Notably, the frequency of fibrosis progression was significantly lower in the resveratrol group (p=0.04).

Conclusion

In conclusion, our findings suggest that resveratrol oral supplement could be considered as a useful adjunctive aid to the established treatment in cases suffering from wet AMD, highlighting the superiority of the combination treatment regimen, since it was accompanied by lower rates of both intravitreal aflibercept injections and progression of macular fibrosis.

Neutrophils promote laser-induced choroidal neovascularization by increasing pro-inflammatory cytokines secretion and cell cycle arrest in retinal pigment epithelium

Inflammation is hypothesized to have essential functions in the development of wet age-related macular degeneration (AMD). Polymorphonuclear neutrophils (PMNs), recognized as major players in inflammation, are typically the first leukocytes to be recruited to an inflammatory site. Previous studies have identified neutrophil aggregates in the lesion site of the choroidal neovascularization model, and systemic depletion of neutrophils in adult mice is associated with reduced choroidal neovascularization (CNV) area, suggesting a pivotal role of PMNs in CNV pathogenesis. Here, we investigate the role of neutrophils in promoting CNV, a key feature of wet AMD. The malfunction and demise of retinal pigment epithelium cells are essential elements in CNV pathogenesis. Our hypothesis posits that neutrophils exacerbate CNV by influencing pro-inflammatory cytokines secreted by retinal pigment epithelium (RPE) cells. Using in vivo laser-induced CNV models with mice and in vitro experiments with the human ARPE-19 cell line, we demonstrated that co-culturing neutrophils with ARPE-19 cells induces an increase in pro-inflammatory cytokines and leads to S-phase cell cycle arrest, potentially through the induction of double-strand breaks (DSBs). Further exploration of this interaction revealed a potential pathway involving reactive oxygen species (ROS) and microRNA-23a, wherein PMNs induce DSBs by initiating the downregulation of LB1 via microRNA-23a. Additionally, we found that dHL-60 cell line could serve as a substitute for primary PMNs, highlighting its potential as a valuable tool in experimental models involving interactions with retinal cells. Our findings underscore the significant role of neutrophils in CNV pathogenesis, providing insights into potential therapeutic targets for wet AMD.

Systemic inflammatory regulators and age-related macular degeneration: a bidirectional Mendelian randomization study

Introduction

We investigated the relationship between systematic regulators of inflammation and the risk of age-related macular degeneration (AMD), both wet and dry forms, by using bidirectional, two-sample Mendelian randomization (MR).

Methods

We performed bidirectional two-sample Mendelian randomization analysis using genome-wide study (GWAS) data for 91 plasma proteins from 14,824 individuals of European descent across 11 study groups. Next, we utilized data from the FinnGen consortium to study AMD using the inverse- variance-weighted approach for Mendelian randomization. Additional analyses involved MR-Egger, Weighted median, Weighted mode, MR-PRESSO, and MR- Steiger filtering techniques.

Results

We identified 16 cytokines associated AMD outcomes and post FDR correction, higher levels of fibroblast growth factor 19 and leukemia inhibitory factor receptor were associated with decreased risk for AMD, while higher levels of tumour necrosis factor ligand superfamily member 14 were associated with increased risk for AMD. Additionally, higher levels of interleukin-10 receptor subunit alpha were associated with decreased risk for wet AMD, higher levels of leukemia inhibitory factor receptor were associated with decreased risk for dry AMD, and higher levels of signaling lymphocytic activation molecule were associated with increased risk for dry AMD. Genetic susceptibility to AMD was associated with elevated levels of TNF-related activation-induced cytokines (TNFSF11), and genetic susceptibility to wet AMD was associated with elevated levels of TNFSF11, interleukin-18 receptor 1 (IL18R1), and CUB domain-containing protein 1 (CDCP1).

Discussion

This research enhances our understanding of systemic inflammation in AMD, providing insights into etiology, diagnosis, and treatment of AMD and its forms.

Fibrosis in age-related neovascular macular degeneration in the anti-VEGF era

The natural history of neovascular age-related macular degeneration (nAMD) leads to scarring and loss of vision. Since the advent of anti-VEGF therapies, which are very effective for controlling exudation, large disciform scars are rarely encountered in the clinic. However long term studies show that smaller and less severe fibrotic scars are not uncommon and develop over time despite optimal treatment. This means that additional mechanisms of action may be required to completely address this condition. To permit new treatments, a proper understanding of the clinical impact of fibrosis is required. This review is focused on clinical aspects of fibrosis and summarises recent data on biomarkers, prevalence, causes, consequences, and therapies, highlighting the most important and urgent topics to tackle in order to advance in the treatment of fibrosis.

The Total Macular Burden of Hyperreflective Foci and the Onset of Persistent Choroidal Hypertransmission Defects in Intermediate AMD

PURPOSE

The association between the total macular burden of hyperreflective foci (HRF) in eyes with intermediate AMD (iAMD) and the onset of persistent choroidal hypertransmission defects (hyperTDs) was studied using swept-source optical coherence tomography (SS-OCT).

DESIGN

Post hoc subgroup analysis of a prospective study.

METHODS

A retrospective review of iAMD eyes from subjects enrolled in a prospective SS-OCT study was performed. All eyes underwent 6×6 mm SS-OCT angiography (SS-OCTA) imaging at baseline and follow-up visits. En face sub-retinal pigment epithelium (subRPE) slabs with segmentation boundaries positioned 64 to 400 µm beneath Bruch's membrane (BM) were used to identify persistent choroidal hyperTDs. None of the eyes had persistent hyperTDs at baseline. The same subRPE slab was used to identify choroidal hypotransmission defects (hypoTDs) attributable to HRF located either intraretinally (iHRF) or along the RPE (rpeHRF) based on corresponding B-scans. A semiautomated algorithm was used by 2 independent graders to validate and refine the HRF outlines. The HRF area and the drusen volume within a 5 mm fovea-centered circle were measured at each visit.

RESULTS

The median follow-up time for the 171 eyes from 121 patients included in this study was 59.1 months (95% CI: 52.0-67.8 months). Of these, 149 eyes (87%) had HRF, and 82 (48%) developed at least one persistent hyperTD during the follow-up. Although univariable Cox regression analyses showed that both drusen volume and total HRF area were associated with the onset of the first persistent hyperTD, multivariable analysis showed that the area of total HRF was the sole significant predictor for the onset of hyperTDs (P < .001). ROC analysis identified an HRF area ≥ 0.07 mm² to predict the onset of persistent hyperTDs within 1 year with an area under the curve (AUC) of 0.661 (0.570-0.753), corresponding to a sensitivity of 55% and a specificity of 74% (P < .001).

CONCLUSIONS

The total macular burden of HRF, which includes both the HRF along the RPE and within the retina, is an important predictor of disease progression from iAMD to the onset of persistent hyperTDs and should serve as a key OCT biomarker to select iAMD patients at high risk for disease progression in future clinical trials.

Targeting the VEGFR2 signaling pathway for angiogenesis and fibrosis regulation in neovascular age-related macular degeneration

Neovascular age-related macular degeneration (nAMD) is characterized by abnormal blood vessel growth from the choroid, leading to complications and eventual blindness. Despite anti-VEGF therapy, subretinal fibrosis remains a major concern, as VEGF/VEGF receptor-2 (VEGFR2) signaling can contribute to both angiogenesis and fibrosis. For the identification of the aqueous humor proteome, we performed liquid chromatography with tandem mass spectrometry analysis. To investigate the potential therapeutic effects of targeting the VEGF signaling pathway using apatinib, a highly selective VEGFR2 tyrosine kinase inhibitor, this study employed in vitro (THP-1 conditioned media-treated ARPE-19 cells) and in vivo (laser-induced choroidal neovascularization mouse) models of nAMD. This study revealed elevated VEGFR2 protein levels in the aqueous humor of nAMD patients, suggesting a potential target to mitigate neovascularization and fibrosis in nAMD. Apatinib effectively reduced VEGFA and αSMA levels in both in vitro and in vivo models. Moreover, apatinib showed improvement in laser-induced subretinal hyper-reflective lesions. The action mechanism was linked to the inhibition of VEGFR2 activation, leading to the suppression of both angiogenesis and fibrosis through the downregulation of STAT3 phosphorylation. Therefore, the VEGFR2 signaling pathway appears to play a central role in the development of nAMD by regulating both angiogenesis and fibrosis.

Recent Insights into Roles of Hypoxia-Inducible Factors in Retinal Diseases

Hypoxia-inducible factors (HIFs) are transcriptional factors that function as strong regulators of oxygen homeostasis and cellular metabolisms. The maintenance of cellular oxygen levels is critical as either insufficient or excessive oxygen affects development and physiologic and pathologic conditions. In the eye, retinas have a high metabolic demand for oxygen. Retinal ischemia can cause visual impairment in various sight-threating disorders including age-related macular degeneration, diabetic retinopathy, and some types of glaucoma. Therefore, understanding the potential roles of HIFs in the retina is highly important for managing disease development and progression. This review focuses on the physiologic and pathologic roles of HIFs as regulators of oxygen homeostasis and cellular metabolism in the retina, drawing on recent evidence. Our summary will promote comprehensive approaches to targeting HIFs for therapeutic purposes in retinal diseases.

MicroRNA expression profiling in tears and blood as predictive biomarkers for anti-VEGF treatment response in wet age-related macular degeneration

PURPOSE

This study aimed to investigate the potential of microRNAs (miRNAs) in tears, blood, and aqueous humor as biomarkers for predicting treatment response in wet age-related macular degeneration (AMD) patients undergoing anti-vascular endothelial growth factor (anti-VEGF) therapy.

METHODS

In a single-center prospective cohort study, treatment-naïve wet AMD patients and age-matched controls were enrolled. Clinical data and miRNA levels (miR-199a-3p, miR-365-3p, miR-200b-3p, miR-195-5p, miR-335-5p, and miR-185-5p) in tears, blood, and aqueous humor were collected. Treatment response was categorized into responders and non-responders based on visual acuity and central subfield thickness. MiRNA levels were quantified using reverse-transcription PCR. Statistical analyses were performed, including ROC analysis, to evaluate predictive accuracy.

RESULTS

Dysregulated miRNA profiles were observed in wet AMD tears and blood compared to controls. Specifically, miR-199a-3p, miR-195-5p, and miR-185-5p were upregulated, while miR-200b-3p was downregulated in tears. All six miRNAs were elevated in wet AMD blood samples. Notably, responders showed higher tear expression of miR-195-5p and miR-185-5p. Combining these miRNAs yielded the highest predictive power (AUC = 0.878, p = 0.006) for anti-VEGF responders.

CONCLUSIONS

Dysregulated miRNA profiles in tears and blood suggest their potential as biomarkers for wet AMD. MiR-195-5p and miR-185-5p in tears demonstrate predictive value for anti-VEGF treatment responders. This study underscores the non-invasive prediction potential of miRNA tear analysis in wet AMD treatment responses.

Stable inhibition of choroidal neovascularization by adeno-associated virus 2/8-vectored bispecific molecules

Neovascular age-related macular degeneration (nAMD) causes severe visual impairment. Pigment epithelium-derived factor (PEDF), soluble CD59 (sCD59), and soluble fms-like tyrosine kinase-1 (sFLT-1) are potential therapeutic agents for nAMD, which target angiogenesis and the complement system. Using the AAV2/8 vector, two bi-target gene therapy agents, AAV2/8-PEDF-P2A-sCD59 and AAV2/8-sFLT-1-P2A-sCD59, were generated, and their therapeutic efficacy was investigated in laser-induced choroidal neovascularization (CNV) and Vldlr-/- mouse models. After a single injection, AAV2/8-mediated gene expression was maintained at high levels in the retina for two months. Both AAV2/8-PEDF-P2A-sCD59 and AAV2/8-sFLT-1-P2A-sCD59 significantly reduced CNV development for an extended period without side effects and provided efficacy similar to two injections of current anti-vascular endothelial growth factor monotherapy. Mechanistically, these agents suppressed the extracellular signal-regulated kinase and nuclear factor-κB pathways, resulting in anti-angiogenic activity. This study demonstrated the safety and long-lasting effects of AAV2/8-PEDF-P2A-sCD59 and AAV2/8-sFLT-1-P2A-sCD59 in CNV treatment, providing a promising therapeutic strategy for nAMD.

The benzoylphenylurea derivative BPU17 acts as an inhibitor of prohibitin and exhibits antifibrotic activity

Inflammation-induced choroidal neovascularization followed by the epithelial-mesenchymal transition (EMT) of retinal pigment epithelial cells (RPEs) is a cause of neovascular age-related macular degeneration (nAMD). RPE-derived myofibroblasts overproduce extracellular matrix, leading to subretinal fibrosis. We already have demonstrated that benzylphenylurea (BPU) derivatives inhibit the function of cancer-associated fibroblasts. Here, we investigated the anti-myofibroblast effects of BPU derivatives and examined such BPU activity on subretinal fibrosis. A BPU derivative, BPU17, exhibits the most potent anti-myofibroblast activity among dozens of BPU derivatives and inhibits subretinal fibrosis in a mouse model of retinal degeneration. Investigations with primary cultured RPEs reveal that BPU17 suppresses cell motility and collagen synthesis in RPE-derived myofibroblasts. These effects depend on repressing the serum response factor (SRF)/CArG-box-dependent transcription. BPU17 inhibits the expression of SRF cofactor, cysteine and glycine-rich protein 2 (CRP2), which activates the SRF function. Proteomics analysis reveals that BPU17 binds to prohibitin 1 (PHB1) and inhibits the PHB1-PHB2 interaction, resulting in mild defects in mitochondrial function. This impairment causes a decrease in the expression of CRP2 and suppresses collagen synthesis. Our findings suggest that BPU17 is a promising agent against nAMD and the close relationship between PHB function and EMT.

JR5558 mice are a reliable model to investigate subretinal fibrosis

Subretinal fibrosis is a major untreatable cause of poor outcomes in neovascular age-related macular degeneration. Mouse models of subretinal fibrosis all possess a degree of invasiveness and tissue damage not typical of fibrosis progression. This project characterises JR5558 mice as a model to study subretinal fibrosis. Fundus and optical coherence tomography (OCT) imaging was used to non-invasively track lesions. Lesion number and area were quantified with ImageJ. Retinal sections, wholemounts and Western blots were used to characterise alterations. Subretinal lesions expand between 4 and 8 weeks and become established in size and location around 12 weeks. Subretinal lesions were confirmed to be fibrotic, including various cell populations involved in fibrosis development. Müller cell processes extended from superficial retina into subretinal lesions at 8 weeks. Western blotting revealed increases in fibronectin (4 wk and 8 wk, p < 0.001), CTGF (20 wks, p < 0.001), MMP2 (12 wks and 20 wks p < 0.05), αSMA (12 wks and 20 wks p < 0.05) and GFAP (8 wk and 12 wk, p ≤ 0.01), consistent with our immunofluorescence results. Intravitreal injection of Aflibercept reduced subretinal lesion growth. Our study provides evidence JR5558 mice have subretinal fibrotic lesions that grow between 4 and 8 weeks and confirms this line to be a good model to study subretinal fibrosis development and assess treatment options.

Aqueous humor cytokine levels in patients with subretinal fibrosis in neovascular age-related macular degeneration

PURPOSE

To investigate aqueous humor cytokine levels in neovascular age-related macular degeneration (nAMD) patients with subretinal fibrosis and to explore the relationship between cytokine levels and disease severity.

METHODS

The aqueous humor samples were collected from 16 eyes with subretinal fibrosis due to nAMD (SRFi group), 33 eyes with nAMD without subretinal fibrosis (nAMD group) and 28 eyes with cataract patients (control group). Clinical samples were analyzed for 5 cytokines,including vascular endothelial growth factor (VEGF), interleukin-6 (IL-6), basic fibroblast growth factor (bFGF), transforming growth factor-α (TGF-α), platelet-derived growth factor-BB (PDGF-BB).

RESULTS

Aqueous humor cytokines VEGF and bFGF were significantly higher in nAMD patients than controls (all P < 0.05), and VEGF, bFGF and TGF-α levels were significantly higher in SRFi patients than controls (all P < 0.05). No significant differences in 4 cytokine levels were observed between nAMD and SRFi patients in aqueous humor. We also identified a positive correlation between the aqueous humor levels of IL-6 and VEGF in the SRFi group, while bFGF and TGF-α in the nAMD group. Moreover, VEGF levels were strongly related to BCVA, and bFGF levels were positively related to the maximum thickness of subretinal hyperreflective material (SHRM) in fibrosis due to nAMD.

CONCLUSION

VEGF and bFGF levels in aqueous humor were elevated in macular neovascularization with and without subretinal fibrosis. TGF-α levels exclusively differed in neovascular AMD with fibrosis. Cytokines are distributed differently and play a synergistic role in different stages (angiogenesis and fibrogenesis) of nAMD. The bFGF levels could predict the negative prognosis in fibrosis due to nAMD.

In vivo monitoring of active subretinal fibrosis in mice using collagen hybridizing peptides

Subretinal fibrosis is associated with worse visual outcomes in patients with neovascular age-related macular degeneration. As there is a lack of optimal biomarkers and no method that directly detects collagen in the back of the eye, novel tools that monitor fibrosis-related changes in neovascular age-related macular degeneration are needed. Here, using two mouse models (the laser-induced choroidal neovascularization model, and the JR5558 mouse presenting with spontaneous subretinal neovascularization with fibrosis), we imaged active fibrotic lesions using fluorescently labeled collagen hybridizing peptides (CHPs), short peptides that bind to single α-chain collagen structures during collagen remodeling. JR5558 retinal pigment epithelium/choroid flat mounts showed CHP co-staining with fibrosis and epithelial mesenchymal transition-related markers; additionally, CHP histopathology staining correlated with in vivo CHP imaging. After laser-induced choroidal neovascularization, in vivo CHP binding correlated with laser intensity, histopathology CHP and fibronectin staining. Laser-induced choroidal neovascularization showed decreased CHP intensity over time in healing/regressing versus active scars in vivo, whereas increased CHP binding correlated with elevated fibrosis in JR5558 mouse eyes with age. In bispecific angiopoietin 2/vascular endothelial growth factor antibody-treated JR5558 mice, CHPs detected significantly decreased collagen remodeling versus immunoglobulin G control. These results demonstrate the first use of CHPs to directly image remodeling collagen in the eye and as a potential clinical optical biomarker of active subretinal fibrosis associated with ocular neovascularization.

Suitability of machine learning for atrophy and fibrosis development in neovascular age-related macular degeneration

PURPOSE

To assess the suitability of machine learning (ML) techniques in predicting the development of fibrosis and atrophy in patients with neovascular age-related macular degeneration (nAMD), receiving anti-VEGF treatment over a 36-month period.

METHODS

An extensive analysis was conducted on the use of ML to predict fibrosis and atrophy development on nAMD patients at 36 months from start of anti-VEGF treatment, using only data from the first 12 months. We use data collected according to real-world practice, which includes clinical and genetic factors.

RESULTS

The ML analysis consistently identified ETDRS as a relevant factor for predicting the development of atrophy and fibrosis, confirming previous statistical analyses. Also, it was shown that genetic variables did not demonstrate statistical relevance in the prediction. Despite the complexity of predicting macular degeneration, our model was able to obtain a balance accuracy of 63% and an AUC of 0.72 when predicting the development of atrophy or fibrosis at 36 months.

CONCLUSION

This study demonstrates the potential of ML techniques in predicting the development of fibrosis and atrophy in nAMD patients receiving long-term anti-VEGF treatment. The findings highlight the importance of clinical factors, particularly ETDRS (early treatment diabetic retinopathy study) visual acuity test, in predicting these outcomes. The lessons learned from this research can guide future ML-based prediction tasks in the field of ophthalmology and contribute to the design of data collection processes.

Exploring the role of granzyme B in subretinal fibrosis of age-related macular degeneration

Age-related macular degeneration (AMD), a prevalent and progressive degenerative disease of the macula, is the leading cause of blindness in elderly individuals in developed countries. The advanced stages include neovascular AMD (nAMD), characterized by choroidal neovascularization (CNV), leading to subretinal fibrosis and permanent vision loss. Despite the efficacy of anti-vascular endothelial growth factor (VEGF) therapy in stabilizing or improving vision in nAMD, the development of subretinal fibrosis following CNV remains a significant concern. In this review, we explore multifaceted aspects of subretinal fibrosis in nAMD, focusing on its clinical manifestations, risk factors, and underlying pathophysiology. We also outline the potential sources of myofibroblast precursors and inflammatory mechanisms underlying their recruitment and transdifferentiation. Special attention is given to the potential role of mast cells in CNV and subretinal fibrosis, with a focus on putative mast cell mediators, tryptase and granzyme B. We summarize our findings on the role of GzmB in CNV and speculate how GzmB may be involved in the pathological transition from CNV to subretinal fibrosis in nAMD. Finally, we discuss the advantages and drawbacks of animal models of subretinal fibrosis and pinpoint potential therapeutic targets for subretinal fibrosis.

Inhibition of hypoxia-inducible factors suppresses subretinal fibrosis

Age-related macular degeneration (AMD) is a common cause of vision loss. The aggressive form of AMD is associated with ocular neovascularization and subretinal fibrosis, representing a responsive outcome against neovascularization mediated by epithelial-mesenchymal transition of retinal pigment epithelium (RPE) cells. A failure of the current treatment (anti-vascular endothelial growth factor therapy) has also been attributed to the progression of subretinal fibrosis. Hypoxia-inducible factors (HIFs) increase gene expressions to promote fibrosis and neovascularization. HIFs act as a central pathway in the pathogenesis of AMD. HIF inhibitors may suppress ocular neovascularization. Nonetheless, further investigation is required to unravel the aspects of subretinal fibrosis. In this study, we used RPE-specific HIFs or von Hippel-Lindau (VHL, a regulator of HIFs) conditional knockout (cKO) mice, along with pharmacological HIF inhibitors, to demonstrate the suppression of subretinal fibrosis. Fibrosis was suppressed by treatments of HIF inhibitors, and similar suppressive effects were detected in RPE-specific Hif1a/Hif2a- and Hif1a-cKO mice. Promotive effects were observed in RPE-specific Vhl-cKO mice, where fibrosis-mediated pathologic processes were evident. Marine products' extracts and their component taurine suppressed fibrosis as HIF inhibitors. Our study shows critical roles of HIFs in the progression of fibrosis, linking them to the potential development of therapeutics for AMD.

Kavain Alleviates Choroidal Neovascularization Via Decreasing the Activity of the HIF-1α/VEGF-A/VEGFR2 Signaling Pathway and Inhibiting Inflammation

Purpose

Neovascular age-related macular degeneration (nAMD) is a prevalent cause of blindness in the elderly. Standard treatment includes anti-vascular endothelial growth factor (anti-VEGF) drugs, such as aflibercept. However, anti-VEGF drugs may have limited efficacy and cause drug resistance. This study explores whether Kavain, an anti-inflammatory molecule from Piper methysticum, can treat choroidal neovascularization (CNV).

Methods

Various experiments were conducted to assess the Kavain's toxicity. The impact of Kavain on in vitro cultured endothelial cells was examined through 5-ethynyl-20-deoxyuridine (EdU) assays, transwell migration assays, and tube formation assays. The therapeutic effects of Kavain on CNV were investigated using a laser-induced CNV mice model. To elucidate the mechanism of Kavain, network pharmacology analysis, molecular docking, and western blots were performed.

Results

Kavain exhibited no apparent toxicity both in vitro and in vivo. Kavain significantly decreased endothelial cell viability, proliferation, migration, and tube formation ability in a dose-dependent manner compared to the hypoxia groups (P<0.05). Kavain alleviated CNV in the laser-induced CNV mouse model compared to the control groups (P<0.05). These effects were statistically significantly enhanced in the Kavain plus aflibercept groups (P<0.05). Following Kavain administration, the expression levels of various inflammatory factors were markedly reduced in retinal pigment epithelium (RPE)/choroid complexes (P<0.05). Mechanistically, Kavain decreased the activity of the hypoxia-inducible factor 1α (HIF-1α)/VEGF-A/ VEGF receptor 2 (VEGFR2) signaling pathway.

Conclusion

Our study is the first to demonstrate Kavain's potential as a promising treatment for nAMD, owing to its dual effects of anti-inflammation and anti-angiogenesis.

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

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

The matricellular protein CCN5 prevents anti-VEGF drug-induced epithelial-mesenchymal transition of retinal pigment epithelium

Age-related macular degeneration (AMD) is one of the major causes of blindness in the elderly worldwide. Anti-vascular endothelial growth factor (VEGF) drugs have been widely used to treat the neovascular type of AMD (nAMD). However, VEGF acts not only as a pro-angiogenic factor but also as an anti-apoptotic factor in the eyes. In this study, we found that anti-VEGF drugs, including bevacizumab (Bev), ranibizumab (Ran), and aflibercept (Afl), induced epithelial-mesenchymal transition (EMT) in ARPE-19 cells in vitro, accompanied by the induction of CCN2, a potent pro-fibrotic factor. Similarly, intravitreal injection of Afl into mouse eyes resulted in EMT in the retinal pigmented epithelium (RPE). Co-treatment with CCN5, an anti-fibrotic factor that down-regulates CCN2 expression, significantly attenuated the adverse effects of the anti-VEGF drugs both in vitro and in vivo. Inhibition of the VEGF signaling pathway with antagonists of VEGF receptors, SU5416 and ZM323881, induced EMT and up-regulated CCN2 in ARPE-19 cells. Additionally, knock-down of CCN2 with siRNA abolished the adverse effects of the anti-VEGF drugs in ARPE-19 cells. Collectively, these results suggest that anti-VEGF drugs induce EMT in RPE through the induction of CCN2 and that co-treatment with CCN5 attenuates the adverse effects of anti-VEGF drugs in mouse eyes.

Features Associated With Vision in Eyes With Subfoveal Fibrosis From Neovascular Age-Related Macular Degeneration

PURPOSE

To report the characteristics and correlation of visual acuity in eyes treated for neovascular age-related macular degeneration (nAMD) and developed fibrosis.

DESIGN

Case-control study.

METHODS

Three hundred fifty-six treatment-naive nAMD eyes that were treated for 12 months were included. Fibrosis was defined as present if well-defined hyperreflective material (HRM) were present between the neurosensory retina and the Bruch membrane on optical coherence tomography (OCT) that correlated with well-defined regions of yellowish pallor on fundus photography and/or staining on fluorescence angiography. OCT features of subfoveal fibrosis and the overlying retina were correlated with visual acuity at month 12.

RESULTS

Sixty-three eyes (20.3%) developed incident fibrosis at month 12. Compared with eyes that did not develop fibrosis, these eyes had lower baseline vision (49 vs 54 letters, P = .02) and more of them had type 2 macular neovascularization (15.0 vs 8.8%, P = .03), larger lesion area (29.6 vs 15.1 mm2, P = .02), and subretinal hemorrhage ≥4 disc diameters (44.4% vs 19.8%, P < .01). Visual acuity was worse in the incident fibrosis compared with the group that never developed fibrosis by month 12. (-1.4±17.1 versus +6.0±17.4 letters, P < .01). In 83 eyes that had subfoveal fibrosis, better vision was associated with intact ellipsoid zone-external limiting membrane complex (β coefficient 29.4, 95% CI 14.2-44.6, P < .01), whereas worse vision was associated with retinal pigment epithelium (RPE)-involving HRM, HRM above the RPE, and width of HRM (β coefficients -25.4 [95% CI -36.3 to -14.6], P < .01; -23.5 [95% CI -39.0 to -7.9], P < .01; and -3.8 [95% CI -7.2 to -0.4], P = .03, respectively).

CONCLUSION

Although fibrosis is associated with poorer visual outcome, preservation of external limiting membrane and level of fibrosis relative to the RPE are associated with visual outcomes.

Role of microglia/macrophage polarisation in intraocular diseases (Review)

Macrophages form a crucial component of the innate immune system, and their activation is indispensable for various aspects of immune and inflammatory processes, tissue repair, and maintenance of the balance of the body's state. Macrophages are found in all ocular tissues, spanning from the front surface, including the cornea, to the posterior pole, represented by the choroid/sclera. The neural retina is also populated by specialised resident macrophages called microglia. The plasticity of microglia/macrophages allows them to adopt different activation states in response to changes in the tissue microenvironment. When exposed to various factors, microglia/macrophages polarise into distinct phenotypes, each exhibiting unique characteristics and roles. Furthermore, extensive research has indicated a close association between microglia/macrophage polarisation and the development and reversal of various intraocular diseases. The present article provides a review of the recent findings on the association between microglia/macrophage polarisation and ocular pathological processes (including autoimmune uveitis, optic neuritis, sympathetic ophthalmia, retinitis pigmentosa, glaucoma, proliferative vitreoretinopathy, subretinal fibrosis, uveal melanoma, ischaemic optic neuropathy, retinopathy of prematurity and choroidal neovascularization). The paradoxical role of microglia/macrophage polarisation in retinopathy of prematurity is also discussed. Several studies have shown that microglia/macrophages are involved in the pathology of ocular diseases. However, it is required to further explore the relevant mechanisms and regulatory processes. The relationship between the functional diversity displayed by microglia/macrophage polarisation and intraocular diseases may provide a new direction for the treatment of intraocular diseases.

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

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

Wnt5a/β-catenin-mediated epithelial-mesenchymal transition: a key driver of subretinal fibrosis in neovascular age-related macular degeneration

BACKGROUND

Neovascular age-related macular degeneration (nAMD), accounts for up to 90% of AMD-associated vision loss, ultimately resulting in the formation of fibrotic scar in the macular region. The pathogenesis of subretinal fibrosis in nAMD involves the process of epithelial-mesenchymal transition (EMT) occurring in retinal pigment epithelium (RPE). Here, we aim to investigate the underlying mechanisms involved in the Wnt signaling during the EMT of RPE cells and in the pathological process of subretinal fibrosis secondary to nAMD.

METHODS

In vivo, the induction of subretinal fibrosis was performed in male C57BL/6J mice through laser photocoagulation. Either FH535 (a β-catenin inhibitor) or Box5 (a Wnt5a inhibitor) was intravitreally administered on the same day or 14 days following laser induction. The RPE-Bruch's membrane-choriocapillaris complex (RBCC) tissues were collected and subjected to Western blot analysis and immunofluorescence to examine fibrovascular and Wnt-related markers. In vitro, transforming growth factor beta 1 (TGFβ1)-treated ARPE-19 cells were co-incubated with or without FH535, Foxy-5 (a Wnt5a-mimicking peptide), Box5, or Wnt5a shRNA, respectively. The changes in EMT- and Wnt-related signaling molecules, as well as cell functions were assessed using qRT-PCR, nuclear-cytoplasmic fractionation assay, Western blot, immunofluorescence, scratch assay or transwell migration assay. The cell viability of ARPE-19 cells was determined using Cell Counting Kit (CCK)-8.

RESULTS

The in vivo analysis demonstrated Wnt5a/ROR1, but not Wnt3a, was upregulated in the RBCCs of the laser-induced CNV mice compared to the normal control group. Intravitreal injection of FH535 effectively reduced Wnt5a protein expression. Both FH535 and Box5 effectively attenuated subretinal fibrosis and EMT, as well as the activation of β-catenin in laser-induced CNV mice, as evidenced by the significant reduction in areas positive for fibronectin, alpha-smooth muscle actin (α-SMA), collagen I, and active β-catenin labeling. In vitro, Wnt5a/ROR1, active β-catenin, and some other Wnt signaling molecules were upregulated in the TGFβ1-induced EMT cell model using ARPE-19 cells. Co-treatment with FH535, Box5, or Wnt5a shRNA markedly suppressed the activation of Wnt5a, nuclear translocation of active β-catenin, as well as the EMT in TGFβ1-treated ARPE-19 cells. Conversely, treatment with Foxy-5 independently resulted in the activation of abovementioned molecules and subsequent induction of EMT in ARPE-19 cells.

CONCLUSIONS

Our study reveals a reciprocal activation between Wnt5a and β-catenin to mediate EMT as a pivotal driver of subretinal fibrosis in nAMD. This positive feedback loop provides valuable insights into potential therapeutic strategies to treat subretinal fibrosis in nAMD patients.

Inactivation of adenosine receptor 2A suppresses endothelial-to-mesenchymal transition and inhibits subretinal fibrosis in mice

Anti-vascular endothelial growth factor therapy has had a substantial impact on the treatment of choroidal neovascularization (CNV) in patients with neovascular age-related macular degeneration (nAMD), the leading cause of vision loss in older adults. Despite treatment, many patients with nAMD still develop severe and irreversible visual impairment because of the development of subretinal fibrosis. We recently reported the anti-inflammatory and antiangiogenic effects of inhibiting the gene encoding adenosine receptor 2A (Adora2a), which has been implicated in cardiovascular disease. Here, using two mouse models of subretinal fibrosis (mice with laser injury-induced CNV or mice with a deficiency in the very low-density lipoprotein receptor), we found that deletion of Adora2a either globally or specifically in endothelial cells reduced subretinal fibrosis independently of angiogenesis. We showed that Adora2a-dependent endothelial-to-mesenchymal transition contributed to the development of subretinal fibrosis in mice with laser injury-induced CNV. Deficiency of Adora2a in cultured mouse and human choroidal endothelial cells suppressed induction of the endothelial-to-mesenchymal transition. A metabolomics analysis of cultured human choroidal endothelial cells showed that ADORA2A knockdown with an siRNA reversed the increase in succinate because of decreased succinate dehydrogenase B expression under fibrotic conditions. Pharmacological inhibition of ADORA2A with a small-molecule KW6002 in both mouse models recapitulated the reduction in subretinal fibrosis observed in mice with genetic deletion of Adora2a. ADORA2A inhibition may be a therapeutic approach to treat subretinal fibrosis associated with nAMD.

Structure-Function Correlation of Retinal Fibrosis in Eyes with Neovascular Age-Related Macular Degeneration

Purpose: To assess retinal function in areas of presumed fibrosis due to neovascular age-related macular degeneration (nAMD), using multimodal imaging and structure-function correlation. Design: Cross-sectional observational study. Methods: 30 eyes of 30 consecutive patients with nAMD with a minimum history of one year of anti-vascular endothelial growth factor therapy were included. Each patient underwent microperimetry (MP), color fundus photography (CFP), standard spectral-domain-based OCT (SD-OCT), and polarization sensitive-OCT (PS-OCT) imaging. PS-OCT technology can depict retinal fibrosis based on its birefringence. CFP, SD-OCT, and PS-OCT were evaluated independently for the presence of fibrosis at the corresponding MP stimuli locations. MP results and morphologic findings in CFP, SD-OCT, and PS-OCT were co-registered and analyzed using mixed linear models. Results: In total, 1350 MP locations were evaluated to assess the functional impact of fibrosis according to a standardized protocol. The estimated means of retinal areas with signs of fibrosis were 12.60 db (95% confidence interval: 10.44-14.76) in CFP, 11.60 db (95% COI: 8.84-14.36) in OCT, and 11.02 db (95% COI 8.10-13.94) in PS-OCT. Areas evaluated as subretinal fibrosis in three (7.2 db) or two (10.1 db) modalities were significantly correlated with a lower retinal sensitivity than a subretinal fibrosis observed in only one (15.3 db) or none (23.3 db) modality (p < 0.001). Conclusions: CFP, SD-OCT and PS-OCT are all suited to detect areas of reduced retinal sensitivity related to fibrosis, however, a multimodal imaging approach provides higher accuracy in the identification of areas with low sensitivity in MP (i.e., impaired retinal function), and thereby improves the detection rate of subretinal fibrosis in nAMD.

Role of immune inflammation regulated by macrophage in the pathogenesis of age-related macular degeneration

Age-related macular degeneration (AMD) can lead to irreversible impairment of visual function, and the number of patients with AMD has been increasing globally. The immunoinflammatory theory is an important pathogenic mechanism of AMD, with macrophages serving as the primary inflammatory infiltrating cells in AMD lesions. Its powerful immunoinflammatory regulatory function has attracted considerable attention. Herein, we provide an overview of the involvement of macrophage-regulated immunoinflammation in different stages of AMD. Additionally, we summarize novel therapeutic approaches for AMD, focusing on targeting macrophages, such as macrophage/microglia modulators, reduction of macrophage aggregation in the subretinal space, modulation of macrophage effector function, macrophage phenotypic alterations, and novel biomimetic nanocomposites development based on macrophage-associated functional properties. We aimed to provide a basis and reference for the further exploration of AMD pathogenesis, developmental influences, and new therapeutic approaches.

Modulation of Extracellular Matrix Composition and Chronic Inflammation with Pirfenidone Promotes Scar Reduction in Retinal Wound Repair

Wound repair in the retina is a complex mechanism, and a deeper understanding of it is necessary for the development of effective treatments to slow down or even prevent degenerative processes leading to photoreceptor loss. In this study, we harnessed a laser-induced retinal degeneration model (532-nm laser photocoagulation with 300 μm spot size, 60 ms duration and 60 mV pulse), enabling a profound molecular elucidation and a comprehensive, prolonged observation of the wound healing sequence in a murine laser-induced degeneration model (C57BL/6J mice, 6-12 weeks) until day 49 post-laser. Our observations included the expression of specific extracellular matrix proteins and myofibroblast activity, along with an analysis of gene expression related to extracellular matrix and adhesion molecules through RNA measurements. Furthermore, the administration of pirfenidone (10 mg/kg via drinking water), an anti-inflammatory and anti-fibrotic compound, was used to modulate scar formation after laser treatment. Our data revealed upregulated collagen expression in late regenerative phases and sustained inflammation in the damaged tissue. Notably, treatment with pirfenidone was found to mitigate scar tissue formation, effectively downregulating collagen production and diminishing the presence of inflammatory markers. However, it did not lead to the regeneration of the photoreceptor layer.

Engineered Knockout of TRPA1 Inhibits Laser-Induced Choroidal Neovascularization Along With Associated TGFβ1 Expression and Neutrophil Infiltration

We examined the effects of gene ablation and chemical inhibition of transient receptor potential ankyrin 1 (TRPA1) on the growth of experimental argon laser-induced choroidal neovascularization (CNV) in mice. CNV was induced in the eyes of 6- to 8-week-old TRPA1-null (knockout [KO]) and wild-type (WT) mice by argon laser irradiation. Gene expression analysis was performed in laser-injured tissues at days 1 and 3. CNV growth was evaluated at day 14. Reciprocal bone marrow transplantation was performed between each genotype to identify the components responsible for either recipient tissue or bone marrow-derived inflammatory cells. Our results show that laser irradiation successfully induced CNV growth at the site of laser injury. The size of induced CNV was significantly smaller in KO mice than in WT mice at day 14, as determined by angiography with fluorescein isothiocyanate-dextran. Invasion of neutrophils, but not macrophages, was suppressed in association with suppression of the expression of transforming growth factor β1 and interleukin 6 in laser-irradiated KO tissue. Bone marrow transplantation indicated that the genotype of the recipient mouse, but not of inflammatory cells, is attributable to the KO phenotype. Systemic administration of a TRPA1 antagonist also reduced the CNV in a WT mouse. In conclusion, TRPA1 signaling in local cells is involved in growth of laser-induced CNV. The phenotype was not attributable to vascular endothelial cells and inflammatory cells. Blocking TRPA1 signal may therefore be a potential treatment strategy for CNV-related ocular diseases.

Metformin regulates the LIN28B‑mediated JNK/STAT3 signaling pathway through miR‑140‑3p in subretinal fibrosis

Subretinal fibrosis (SF) is an important cause of submacular neovascularization that leads to permanent vision loss, but has no effective clinical treatment. The present study examined the influence of metformin on SF, and investigated whether the mechanism involves the microRNA (miR)-140-3p/LIN28B/JNK/STAT3-mediated regulation of oxidative stress, angiogenesis and fibrosis-associated indicators. A mouse model of laser-induced SF was established. In addition, an ARPE-19 fibrotic cell model was established using TGF-β1. A Cell Counting Kit-8 assay was used to examine cell viability. Flow cytometry was used to measure reactive oxygen species levels, and western blotting was used to detect the levels of proteins associated with epithelial-mesenchymal transition (EMT), signaling and fibrosis. The levels of superoxide dismutase, malondialdehyde, glutathione-peroxidase and catalase were measured using kits. Scratch assays and Transwell assays were used to assess cell migration and invasion, respectively, and reverse transcription-quantitative PCR was used to determine the levels of miR-140-3p and LIN28B. Dual-luciferase assays were used to verify the targeting relationship between miR-140-3p and LIN28B, and coimmunoprecipitation was used to confirm the interaction between LIN28B and JNK. Masson staining and hematoxylin and eosin staining were used to examine collagenous fibers and the histopathology of eye tissue. In ARPE-19 cells induced by TGF-β1, metformin promoted miR-140-3p expression and inhibited LIN28B expression and JNK/STAT3 pathway activation, thereby inhibiting oxidative stress, EMT and fibrosis in ARPE-19 cells. The overexpression of LIN28B or treatment with the JNK/STAT3 agonist anisomycin partially reversed the inhibitory effect of metformin on oxidative stress and fibrosis in ARPE-19 cells. The dual-luciferase reporter assay and coimmunoprecipitation assay showed that miR-140-3p targeted the 3' untranslated region of LIN28B mRNA and inhibited LIN28B expression. LIN28B targeted and bound to JNK and regulated the JNK/STAT3 pathway. Therefore, it may be concluded that metformin can promote miR-140-3p expression, inhibit LIN28B and then inhibit the JNK/STAT3 pathway to alleviate SF.

Roles and mechanisms of long non-coding RNAs in age-related macular degeneration

Worldwide, age-related macular degeneration (AMD) is a multifactorial progressive fundus disorder that can cause vision impairment and severe central blindness in older adults. Currently, there are no approved prevention or treatment strategies for non-exudative AMD. While targeting VEGF is the main therapeutic approach to delay the degeneration process in exudative AMD, a significant number of patients show insensitivity or ineffectiveness to anti-VEGF therapy. Despite years of research, the exact mechanism underlying drusen formation and macular atrophy in AMD remains unknown. In the pathogenesis of AMD, lncRNAs play crucial roles, as discussed in this paper. This review focuses on the function of dysregulated lncRNAs and the mechanisms by which specific molecules target these lncRNAs in AMD. The analysis reveals that lncRNAs primarily regulate the progression of AMD by mediating apoptosis, epithelial-mesenchymal transition (EMT), dedifferentiation, and oxidative stress in choroidal vascular endothelial cells, retinal pigment epithelium (RPE) cells, and photoreceptors. Consequently, the regulation of apoptosis, dedifferentiation, EMT, and other processes by lncRNAs has emerged as a crucial focus in AMD research.These findings contribute to our understanding of the role of lncRNAs in AMD and their potential as valuable biomarkers. Furthermore, they highlight the need for further basic and clinical studies to explore the value of lncRNAs as biomarkers and potential therapeutic targets for AMD.

MiR-21 Participates in Anti-VEGF-Induced Epithelial Mesenchymal Transformation in RPE Cells

Background

To explore the role and possible mechanism of miR-21 in anti-VEGF drug-induced epithelial-mesenchymal transformation (EMT) in human retinal pigment epithelium (ARPE-19) cells, and to seek more therapeutic targets to improve prognosis vision.

Methods

ARPE-19 cells were exposed to clinical dosage of bevacizumab and miR-21 expression was measured by real-time polymerase chain reaction (RT-PCR) assay. MiR-21 mimic and inhibitor were transfected into bevacizumab-induced ARPE-19, the expression of α-smooth muscle actin (α-SMA), E-cadherin, and SNAI1 were detected by cell immunofluorescence and Western blotting.

Results

Clinical dosage of bevacizumab caused EMT and enhanced miR-21 expression in ARPE-19 cells (P<0.05). The inhibition of miR-21 attenuated the EMT effect of bevacizumab, while overexpression of miR-21 promoted this activity (P<0.05). The SNAI1 was up-regulated by bevacizumab and promotion was partially suppressed by the miR-21 inhibitor and aggravated by the miR-21 mimic (P<0.05).

Conclusion

MiR-21 promotes bevacizumab-induced EMT in ARPE cells which is significantly positively correlated with SNAI1. MiR-21 might be a potential miRNA-based therapeutic target for reducing bevacizumab-induced subretinal fibrosis.

Extracellular vesicles from retinal pigment epithelial cells expressing R345W-Fibulin-3 induce epithelial-mesenchymal transition in recipient cells

We have shown previously that expression of R345W-Fibulin-3 induces epithelial-mesenchymal transition (EMT) in retinal pigment epithelial (RPE) cells. The purpose of the current study was to determine if extracellular vesicles (EVs) derived from RPE cells expressing R345W-Fibulin-3 mutation are sufficient to induce EMT in recipient cells. ARPE-19 cells were infected with luciferase-tagged wild-type (WT)- Fibulin-3 or luciferase-tagged R345W-Fibulin-3 (R345W) using lentiviruses. EVs were isolated from the media by ultracentrifugation or density gradient ultracentrifugation. Transmission electron microscopy and cryogenic electron microscopy were performed to study the morphology of the EVs. The size distribution of EVs were determined by nanoparticle tracking analysis (NTA). EV cargo was analysed using LC-MS/MS based proteomics. EV-associated transforming growth factor beta 1 (TGFβ1) protein was measured by enzyme-linked immunosorbent assay. The capacity of EVs to stimulate RPE migration was evaluated by treating recipient cells with WT- or R345W-EVs. The role of EV-bound TGFβ was determined by pre-incubation of EVs with a pan-TGFβ blocking antibody or IgG control. EM imaging revealed spherical vesicles with two subpopulations of EVs: a group with diameters around 30 nm and a group with diameters over 100 nm, confirmed by NTA analysis. Pathway analysis revealed that members of the sonic hedgehog pathway were less abundant in R345W- EVs, while EMT drivers were enriched. Additionally, R345W-EVs had higher concentrations of TGFβ1 compared to control. Critically, treatment with R345W-EVs was sufficient to increase EMT marker expression, as well as cell migration in recipient cells. This EV-increased cell migration was significantly inhibited by pre-incubation of EVs with pan-TGFβ-neutralising antibody. In conclusion, the expression of R345W-Fibulin-3 alters the size and cargo of EVs, which are sufficient to enhance the rate of cell migration in a TGFβ dependent manner. These results suggest that EV-bound TGFβ plays a critical role in the induction of EMT in RPE cells.

Contribution of common and rare variants to Asian neovascular age-related macular degeneration subtypes

Neovascular age-related macular degeneration (nAMD), along with its clinical subtype known as polypoidal choroidal vasculopathy (PCV), are among the leading causes of vision loss in elderly Asians. In a genome-wide association study (GWAS) comprising 3,128 nAMD (1,555 PCV and 1,573 typical nAMD), and 5,493 controls of East Asian ancestry, we identify twelve loci, of which four are novel ([Formula: see text]). Substantial genetic sharing between PCV and typical nAMD is noted (rg = 0.666), whereas collagen extracellular matrix and fibrosis-related pathways are more pronounced for PCV. Whole-exome sequencing in 259 PCV patients revealed functional rare variants burden in collagen type I alpha 1 chain gene (COL1A1; [Formula: see text]) and potential enrichment of functional rare mutations at AMD-associated loci. At the GATA binding protein 5 (GATA5) locus, the most significant GWAS novel loci, the expressions of genes including laminin subunit alpha 5 (Lama5), mitochondrial ribosome associated GTPase 2 (Mtg2), and collagen type IX alpha 3 chain (Col9A3), are significantly induced during retinal angiogenesis and subretinal fibrosis in murine models. Furthermore, retinoic acid increased the expression of LAMA5 and MTG2 in vitro. Taken together, our data provide insights into the genetic basis of AMD pathogenesis in the Asian population.

Dasatinib Plus Quercetin Alleviates Choroid Neovascularization by Reducing the Cellular Senescence Burden in the RPE-Choroid

Purpose

Wet AMD (wAMD) is associated with cellular senescence. However, senescent cell-targeted therapies for wAMD have rarely been comprehensively studied. This study aimed to explore the therapeutic effects of senolytic agents on choroidal neovascularization (CNV).

Methods

RNA sequencing datasets were obtained from the Gene Expression Omnibus database and used to explore the association between senescence and wAMD. We explored the effects of senescent adult RPE cell line-19 cells on the proliferation, migration, invasion, and tube formation of human umbilical vein endothelial cells. A laser-induced CNV animal model was used to study wAMD. We studied a senescent cell elimination therapy for CNV progression using two types of senolytics and a transgenic method.

Results

Cells in the retinal pigment epithelium-choroid of the CNV model were enriched in senescence, inflammation, and angiogenesis gene sets. AP20187 was used to specifically eliminate senescent cells and proven to alleviate CNV progression in INK-ATTAC transgenic mice. Senescent adult RPE cell line-1 cells produced elevated levels of senescence-associated secretory phenotypes, including VEGFs; they also demonstrated increased proliferation, migration, invasion, and tube formation in human umbilical vein endothelial cells. The number of senescent cells increased in the laser-induced CNV rat model, and intravitreal injections of dasatinib with quercetin reduced the expression of p16 in CNV and alleviated neovascularization.

Conclusions

Senescent RPE cells can accelerate pathological neovascularization; thus, senescent cell-targeting therapy has great clinical potential for wAMD.

Fibrosis in neovascular age-related macular degeneration: A review of definitions based on clinical imaging

Despite the success of antiangiogenic therapy in controlling exudation in neovascular age-related macular degeneration (nAMD), the involvement of the outer retina in fibrosis results in gradual vision loss over time. The development of drugs that prevent or ameliorate fibrosis in nAMD requires that it is accurately detected and quantified with reliable endpoints and identification of robust biomarkers. Achievement of such an aim is currently challenging due to the lack of a consensus definition of fibrosis in nAMD. As a first step towards the establishment of a clear definition of fibrosis, we provide an extensive overview of the imaging modalities and criteria used to characterize fibrosis in nAMD. We observed variety in the selection of individual and combinations of imaging modalities, and criteria for detection. We also observed heterogeneity in classification systems and severity scales for fibrosis. The most commonly used imaging modalities were color fundus photography, fluorescein angiography and optical coherence tomography (OCT). A multimodal approach was frequently utilized. Our review suggests that OCT offers a more detailed, objective and sensitive characterization than color fundus photography/fluorescein angiography. Thus, we recommend it as a primary modality for fibrosis evaluation. This review provides a basis for future discussions to reach a consensus definition using standardized terms based on a detailed characterization of fibrosis, its presence and evolution, and taking into consideration impact on visual function. Achieving this goal is of paramount importance for the development of antifibrotic therapies.

Molecular pathogenesis of subretinal fibrosis in neovascular AMD focusing on epithelial-mesenchymal transformation of retinal pigment epithelium

Age-related macular degeneration (AMD) is a leading cause of vision loss among elderly people in developed countries. Neovascular AMD (nAMD) accounts for more than 90% of AMD-related vision loss. At present, intravitreal injection of anti-vascular endothelial growth factor (anti-VEGF) is widely used as the first-line therapy to decrease the choroidal and retinal neovascularizations, and thus to improve or maintain the visual acuity of the patients with nAMD. However, about 1/3 patients still progress to irreversible visual impairment due to subretinal fibrosis even with adequate anti-VEGF treatment. Extensive literatures support the critical role of epithelial-mesenchymal transformation (EMT) of retinal pigment epithelium (RPE) in the pathogenesis of subretinal fibrosis in nAMD, but the underlying mechanisms still remain largely unknown. This review summarized the molecular pathogenesis of subretinal fibrosis in nAMD, especially focusing on the transforming growth factor-β (TGF-β)-induced EMT pathways. It was also discussed how these pathways crosstalk and respond to signals from the microenvironment to mediate EMT and contribute to the progression of nAMD-related subretinal fibrosis. Targeting EMT signaling pathways might provide a promising and effective therapeutic strategy to treat subretinal fibrosis secondary to nAMD.

METTL3-mediated m6A modification of HMGA2 mRNA promotes subretinal fibrosis and epithelial-mesenchymal transition

Subretinal fibrosis is a major cause of the poor visual prognosis for patients with neovascular age-related macular degeneration (nAMD). Myofibroblasts originated from retinal pigment epithelial (RPE) cells through epithelial-mesenchymal transition (EMT) contribute to the fibrosis formation. N6-Methyladenosine (m6A) modification has been implicated in the EMT process and multiple fibrotic diseases. The role of m6A modification in EMT-related subretinal fibrosis has not yet been elucidated. In this study, we found that during subretinal fibrosis in the mouse model of laser-induced choroidal neovascularization, METTL3 was upregulated in RPE cells. Through m6A epitranscriptomic microarray and further verification, high-mobility group AT-hook 2 (HMGA2) was identified as the key downstream target of METTL3, subsequently activating potent EMT-inducing transcription factor SNAIL. Finally, by subretinal injections of adeno-associated virus vectors, we confirmed that METTL3 deficiency in RPE cells could efficiently attenuate subretinal fibrosis in vivo. In conclusion, our present research identified an epigenetic mechanism of METTL3-m6A-HMGA2 in subretinal fibrosis and EMT of RPE cells, providing a novel therapeutic target for subretinal fibrosis secondary to nAMD.

Ten-Year Incidence of Fibrosis and Risk Factors for Its Development in Neovascular Age-Related Macular Degeneration

PURPOSE

To report the incidence and risk factors for fibrosis at 10 years in a large cohort of persons with neovascular age-related macular degeneration (nAMD).

DESIGN

Retrospective, multicenter, cohort study.

METHODS

We included 225 naive nAMD eyes that underwent intravitreal anti-vascular endothelial growth factor treatment over 10 years of follow-up at two Italian referral centers. Demographic and clinical data were reviewed at baseline and on an annual basis. Onset of fibrosis was defined by clinically assessing photographs, fundus descriptions, or fluorescein angiograms. Optical coherence tomography (OCT) scans of fibrosis were inspected by an external reading center and graded as subretinal pigment epithelium (RPE), mixed, or subretinal.

RESULTS

The mean age at baseline was of 72.1 ± 6.9 years. The incidence rate of fibrosis was estimated to be 8.9 per 100 person-years, with a cumulative incidence of 62.7% at 10 years. Fibrotic lesions were sub-RPE in 46.1%, mixed in 29.8%, and subretinal in 22.7%. Independent factors associated with fibrosis included the following: larger central subfield thickness variation (P < .001), submacular hemorrhages (P = .008), higher number of injections (P = .01), and worse baseline visual acuity (VA) (P = .03). Type 2 macular neovascularization was significantly associated with mixed and subretinal fibrosis. VA significantly declined over 10 years (-16.4 Early Treatment Diabetic Retinopathy Study [ETDRS] letters), particularly in eyes with mixed and subretinal fibrosis (P < .001).

CONCLUSIONS

We identified a 62.7% cumulative incidence of fibrosis in a large nAMD cohort at 10 years. Fibrosis was more common with frequent reactivations and lower baseline VA; its onset had a significant impact on final VA. This supports the hypothesis that nAMD patients should be promptly treated with proactive regimens.

Advances in development of exosomes for ophthalmic therapeutics

Exosomes contain multiple bioactive molecules and maintain the connection between cells. Recent advances in exosome-based therapeutics have witnessed unprecedented opportunities in treating ophthalmic diseases, including traumatic diseases, autoimmune diseases, chorioretinal diseases and others. Utilization of exosomes as delivery vectors to encapsulate both drugs and therapeutic genes could yield higher efficacy and avoid the unnecessary immune responses. However, exosome-based therapies also come with some potential ocular risks. In this review, we first present a general introduction to exosomes. Then we provide an overview of available applications and discuss their potential risks. Moreover, we review recently reported exosomes as delivery vectors for ophthalmic diseases. Finally, we put forward future perspectives to grapple with its translation and underlying issues.

Strategic outline of interventions targeting extracellular matrix for promoting healthy longevity

The extracellular matrix (ECM), composed of interlinked proteins outside of cells, is an important component of the human body that helps maintain tissue architecture and cellular homeostasis. As people age, the ECM undergoes changes that can lead to age-related morbidity and mortality. Despite its importance, ECM aging remains understudied in the field of geroscience. In this review, we discuss the core concepts of ECM integrity, outline the age-related challenges and subsequent pathologies and diseases, summarize diagnostic methods detecting a faulty ECM, and provide strategies targeting ECM homeostasis. To conceptualize this, we built a technology research tree to hierarchically visualize possible research sequences for studying ECM aging. This strategic framework will hopefully facilitate the development of future research on interventions to restore ECM integrity, which could potentially lead to the development of new drugs or therapeutic interventions promoting health during aging.

7-Ketocholesterol Promotes Retinal Pigment Epithelium Senescence and Fibrosis of Choroidal Neovascularization via IQGAP1 Phosphorylation-Dependent Signaling

Accumulation of 7-ketocholesterol (7KC) occurs in age-related macular degeneration (AMD) and was found previously to promote fibrosis, an untreatable cause of vision loss, partly through induction of endothelial-mesenchymal transition. To address the hypothesis that 7KC causes mesenchymal transition of retinal pigment epithelial cells (RPE), we exposed human primary RPE (hRPE) to 7KC or a control. 7KC-treated hRPE did not manifest increased mesenchymal markers, but instead maintained RPE-specific proteins and exhibited signs of senescence with increased serine phosphorylation of histone H3, serine/threonine phosphorylation of mammalian target of rapamycin (p-mTOR), p16 and p21, β-galactosidase labeling, and reduced LaminB1, suggesting senescence. The cells also developed senescence-associated secretory phenotype (SASP) determined by increased IL-1β, IL-6, and VEGF through mTOR-mediated NF-κB signaling, and reduced barrier integrity that was restored by the mTOR inhibitor, rapamycin. 7KC-induced p21, VEGF, and IL-1β were inhibited by an inhibitor of protein kinase C. The kinase regulates IQGAP1 serine phosphorylation. Furthermore, after 7KC injection and laser-induced injury, mice with an IQGAP1 serine 1441-point mutation had significantly reduced fibrosis compared to littermate control mice. Our results provide evidence that age-related accumulation of 7KC in drusen mediates senescence and SASP in RPE, and IQGAP1 serine phosphorylation is important in causing fibrosis in AMD.