Direct effect of sodium iodate on neurosensory retina

Sodium-iodate injection can replicate retinal and choroid degeneration in pigmented mice: Using multimodal imaging and label-free quantitative proteomics analysis

Age-related macular degeneration (AMD) is the leading cause of irreversible visual loss in the elderly population. Sodium iodate (NaIO3), a stable oxidizing agent, has been injected to establish a reproducible model of oxidative stress-induced RPE and photoreceptor death. The aim of our study was to evaluate the morphological and molecular changes of retina and retinal pigment epithelium (RPE)-choroid in NaIO3-treated mouse using multimodal fundus imaging and label-free quantitative proteomics analysis. Here, we found that following NaIO3 injection, retinal degeneration was evident. Fundus photographs showed numerous scattered yellow-white speckled deposits. Optical coherence tomography (OCT) images indicated disruption of the retinal layers, damage of the RPE layer and accumulation of hyper-reflective matter in multiple layers of the outer retina. Widespread foci of a high fundus autofluorescence (FAF) signal were noticed. Fundus fluorescein angiography (FFA) revealed diffuse intense transmitted fluorescence mixed with scattered spot-like blocked fluorescence. Indocyanine green angiography (ICGA) presented punctate hyperfluorescence. Due to the atrophy of the RPE and Bruch's membrane and choroidal capillary complex, the larger choroidal vessels become more prominent in ICGA and optical coherence tomography angiography (OCTA). Transmission electron microscope (TEM) illustrated abnormal material accumulation and damaged mitochondria. Bioinformatics analysis of proteomics revealed that the differentially expressed proteins participated in diverse biological processes, encompassing phototransduction, NOD-like receptor signaling pathway, phagosome, necroptosis, and cell adhesion molecules. In conclusion, by multimodal imaging, we described the phenotype of NaIO3-treated mouse model mimicking oxidative stress-induced RPE and photoreceptor death in detail. In addition, proteomics analysis identified differentially expressed proteins and significant enrichment pathways, providing insights for future research, although the exact mechanism of oxidative stress-induced RPE and photoreceptor death remains incompletely understood.

Small molecule SIRT1 activators counteract oxidative stress-induced inflammasome activation and nucleolar stress in retinal degeneration

BACKGROUND

The nicotinamide adenosine dinucleotide-dependent deacetylase Sirtuin 1 (SIRT1) has been identified as a protective factor that inhibits the activation of nucleotide-binding and oligomerization domain-, leucine-rich repeat-, and pyrin domain-containing protein 3 (NLRP3) inflammasome. However, whether pharmacological SIRT1 activators can protect retinal pigment epithelial (RPE) cells against oxidative and inflammatory injuries related to age-related macular degeneration remains to be explored.

METHODS

Two small molecule specific SIRT1 activators (SRT2104 and CAY10602) were tested, with resveratrol being used as a positive control. Mouse models with sodium iodate-induced retinal degeneration were constructed. ARPE-19 cells in culture were used for in vitro experiments. The effects of SIRT1 activators on H2O2-induced ARPE-19 cell injury were determined by reactive oxygen species quantification, western blotting, flow cytometry and immunofluorescence staining. In vivo, the severity of retinal damage was assessed using flash electroretinography and histopathological analysis.

RESULTS

In vitro, SRT2104, CAY10602 and resveratrol significantly attenuated H2O2-induced cell death, nucleolar stress response, and reactive oxygen species accumulation. In H2O2-stimulated cells, SIRT1 activators reduced the level of NLRP3, inhibited the activation of caspase-1, and decreased the production of interleukin (IL)-1β and IL-18. The inhibitory effects of SIRT1 activators on caspase-1 activation and IL-1β production were blunted by SIRT1 gene silencing. In vivo, treatment with SRT2104 or CAY10602 in mice with sodium iodate-induced retinal degeneration markedly improved the retinal functions and reduced the loss of RPE cells.

CONCLUSION

Our study suggests that small molecule SIRT1 activators are effective for protection of RPE cells against oxidative stress-induced NLRP3 inflammasome activation, highlighting potential applications in the treatment of macular degeneration associated RPE dysfunctions.

Leading edge of the a-wave of the electroretinogram and sodium iodate-induced age-related macular degeneration: A model

BACKGROUND

Iron-induced oxidative stress was thought to be the reason why the a-wave amplitude of the electroretinogram (ERG) dropped when iron ions were present. It is assumed that reactive oxygen species (ROS) are generated in the presence of iron ions, and this leads to a decrease in hyperpolarization of the photoreceptor. It is known that in age-related macular degeneration (AMD), sodium iodate can induce oxidative stress, apoptosis, and retinal damage, which mimic the effects of clinical AMD. Here, the reduction of the a-wave amplitude in mice with sodium iodate-induced age-related macular degeneration is explained.

METHODS

The leading edge of the a-wave is divided into voltages developed by cones and rods. The same oxidative stress model is applied here since sodium iodate causes the creation of ROS in a manner similar to that caused by iron ions, with the exception that the retina is treated as a circuit of various resistances when computing the photoresponse. Moreover, sodium iodate also leads to apoptosis and, hence, may cause misalignment in cones (not in rods) during the initial stage of apoptosis in AMD. To include the effects of apoptosis and shortening in cones and rods, we have used a factor representing the fraction of total cones and rods that are alive. To include the effect of misalignment of cones on the reduction of the a-wave amplitude, we have used the Stiles-Crawford function to calculate the number of photoisomerizations occurring in a photoreceptor misaligned at an angle θ. The results are compared with experimental data.

RESULTS

In sodium iodate-treated eyes, the ROS produced can attract calcium ions in the photoreceptor, which increases the calcium influx. In the case of the cones, the inclusion of the misalignment angle in the phototransduction process helps in determining the voltage and slope of the voltage vs. time graph.The smaller the fraction of active photoreceptors, the smaller the amplitude of the a-wave. The calcium influx, misaligned photoreceptors, and total photoreceptor loss all cause the amplitude of the a-wave to decrease, and at any time from the beginning of phototransduction cascade, the calcium influx causes the slope of the a-wave to increase.

CONCLUSION

The reduction in the a-wave amplitude in the eyes of sodium iodate-treated mice is attributed to oxidative stress in both cones and rods and cone misalignment, which ultimately lead to apoptosis and vision loss in AMD.

Retinal debris triggers cytotoxic damage in cocultivated primary porcine RPE cells

Introduction

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

Methods

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

Results

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

Discussion

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

Lemon Peel Water Extract: A Novel Material for Retinal Health, Protecting Retinal Pigment Epithelial Cells against Dynamin-Related Protein 1-Mediated Mitochondrial Fission by Blocking ROS-Stimulated Mitogen-Activated Protein Kinase/Extracellular Signal-Regulated Kinase Pathway

Previous studies showed that NaIO3 can induce oxidative stress-mediated retinal pigment epithelium (RPE) damage to simulate age-related macular degeneration (AMD). Lemon peel is rich in antioxidants and components that can penetrate the blood-retinal barrier, but their role in retinal oxidative damage remains unexplored. Here, we explore the protection of lemon peel ultrasonic-assisted water extract (LUWE), containing large amounts of flavonoids and polyphenols, against NaIO3-induced retinal degeneration. We initially demonstrated that LUWE, orally administered, prevented retinal distortion and thinning on the inner and outer nuclei layers, downregulating cleaved caspase-3 protein expression in RPE cells in NaIO3-induced mice. The effect of LUWE was achieved through the suppression of apoptosis and the associated proteins, such as cleaved PARP and cleaved caspase-3, as suggested by NaIO3-induced ARPE-19 cell models. This is because LUWE reduced reactive oxygen species-mediated mitochondrial fission via regulating p-Drp-1 and Fis1 expression. We further confirmed that LUWE suppresses the expression of p-MEK-1/2 and p-ERK-1/2 in NaIO3-induced ARPE-19 cells, thereby providing the protection described above, which was confirmed using PD98059 and U0126. These results indicated that LUWE prevents mitochondrial oxidative stress-mediated RPE damage via the MEK/ERK pathway. Elucidation of the molecular mechanism may provide a new protective strategy against retinal degeneration.

Targeting ZIP8 mediated ferroptosis as a novel strategy to protect against the retinal pigment epithelial degeneration

The degeneration of retinal pigment epithelium (RPE) plays an important role in the development of age-related macular degeneration (AMD). However, the underlying mechanism remains elusive. In this study, we identified that ZIP8, a metal-ion transporter, plays a crucial role in the degeneration of RPE cells mediated by ferroptosis. ZIP8 was found to be upregulated in patients with AMD through transcriptome analysis. Upregulated ZIP8 was also observed in both oxidative-stressed RPE cells and AMD mouse model. Importantly, knockdown of ZIP8 significantly inhibited ferroptosis in RPE cells induced by sodium iodate-induced oxidative stress. Blocking ZIP8 with specific antibodies reversed RPE degeneration and restored retinal function, improving visual loss in a mouse model of NaIO3-induced. Interestingly, the modification of the N-glycosylation sites N40, N72 and N88, but not N273, was essential for the intracellular iron accumulation mediated by ZIP8, which further led to increased lipid peroxidation and RPE death. These findings highlight the critical role of ZIP8 in RPE ferroptosis and provide a potential target for the treatment of diseases associated with retinal degeneration, including AMD.

Optimizing the sodium iodate model: Effects of dose, gender, and age

Sodium iodate (NaIO3) is a commonly used model for age-related macular degeneration (AMD), but its rapid and severe induction of retinal pigment epithelial (RPE) and photoreceptor degeneration can lead to the premature dismissal of potentially effective therapeutics. Additionally, little is known about how sex and age affect the retinal response to NaIO3. This study aims to establish a less severe yet reproducible regimen by testing low doses of NaIO3 while considering age- and sex-related effects, enabling a broader range of therapeutic evaluations. In this study, young (3-5 months) and old (18-24 months) male and female C57Bl/6J mice were given an intraperitoneal (IP) injection of 15, 20, or 25 mg/kg NaIO3. Damage assessment one week post-injection included in vivo imaging, histological examination, and qRT-PCR analysis. The results revealed that young mice showed no damage at 15 mg/kg IP NaIO3, with varying degrees of damage observed at 20 mg/kg. At 25 mg/kg, most young mice displayed widespread retinal damage, with females exhibiting less retinal thinning than males. In contrast, older mice at 20 and 25 mg/kg displayed a more patchy degeneration pattern, outer retinal undulations, and greater variability in degeneration than the young mice. The most effective model for minimizing damage while maintaining consistency utilizes young female mice injected with 25 mg/kg NaIO3. The observed sex- and age-related differences underscore the importance of considering these variables in research, aligning with the National Institutes of Health's guidance. While the model does not fully replicate the complexity of AMD, these findings enhance its utility as a valuable tool for testing RPE/photoreceptor protective or replacement therapies.

CX3CL1/CX3CR1 Signaling Mediated Neuroglia Activation Is Implicated in the Retinal Degeneration: A Potential Therapeutic Target to Prevent Photoreceptor Death

Purpose

Retinal degeneration (RD) is a large cluster of retinopathies that is characterized by the progressive photoreceptor death and visual impairments. CX3CL1/CX3CR1 signaling has been documented to mediate the microglia activation and gliosis reaction during neurodegeneration. We intend to verify whether the CX3CL1/CX3CR1 signaling is involved in the RD pathology.

Methods

A pharmacologically induced RD mice model was established. AZD8797, a CX3CR1 antagonist, was injected into the vitreous cavity of an RD model to modulate the neuroglia activation. Then, the experimental animals were subjected to functional, morphological, and behavioral analysis.

Results

The CX3CL1/CX3CR1 signaling mediated neuroglia activation was implicated in the photoreceptor demise of an RD model. Intravitreal injection of AZD8797 preserved the retinal structure and enhanced the photoreceptor survival through inhibiting the CX3CL1/CX3CR1 expressions. Fundus photography showed that the distribution of retinal vessel was clear, and the severity of lesions was alleviated by AZD8797. In particular, these morphological benefits could be translated into remarkable functional improvements, as evidenced by the behavioral test and electroretinogram (mf-ERG) examination. A mechanism study showed that AZD8797 mitigated the microglia activation and migration in the degenerative retinas. The Müller cell hyper-reaction and secondary gliosis response were also suppressed by AZD8797.

Conclusions

The neuroinflammation is implicated in the photoreceptor loss of RD pathology. Targeting the CX3CL1/CX3CR1 signaling may serve as an effective therapeutic strategy. Future refinements of these findings may cast light into the discovery of new medications for RD.

Potassium Iodate Retinotoxicity after an Overdose of Anti-Radiation Pills: A Case of Apocalyptic Retinopathy

PURPOSE

To report a case of severe retinal toxicity after an attempted suicidal overdose of anti-radiation pills containing a well-known retinal pigment epithelial toxin, potassium iodate.

METHODS

Clinical examination and multimodal imaging are provided from a clinic visit eleven years after the suicide attempt.

RESULTS

The 42-year-old patient had widespread retinal atrophy in both eyes with near complete absence of the retinal pigment epithelium and severe retinal thinning. A few remaining areas of preserved photoreceptors provided her with 20/60 and 20/200 vision in her right and left eyes, respectively, with very constricted visual fields.

CONCLUSION

Despite being first described over 100 years ago, few cases of iodate retinotoxicity have been reported in the published literature, and most are related to accidental or intentional ingestion of iodate salts used to iodize table salt. This unique case of iodate retinotoxicity secondary to anti-radiation tablets highlights the risks of unregulated sale of these agents marketed in the United States as essential components of nuclear apocalypse "go bags" because they have a poor margin-of-safety and no specific warnings of the risk of permanent blindness with overdosage.

Protective Effect and Related Mechanism of Modified Danggui Buxue Decoction on Retinal Oxidative Damage in Mice based on Network Pharmacology

INTRODUCTION

Age-related macular degeneration (AMD) is one of the common diseases that cause vision loss in the elderly, and oxidative stress has been considered a major pathogenic factor for AMD. Modified Danggui Buxue Decoction (RRP) has a good therapeutic effect on non-proliferatic diabetic retinopathy and can improve the clinical symptoms of patients.

METHODS

The key ingredients and core targets of RRP protecting retinal oxidative damage were obtained by Network pharmacology analysis. A mouse retinal oxidative damage model induced by tail vein injection of 1% NaIO3 solution (25 mg/kg) was treated with RRP for 4 weeks and used to verify the pharmacodynamics and related mechanism.

AIM

This study aimed to predict and verify the protective effect and mechanism of RRP on retinal oxidative damage in mice based on network pharmacology and animal experiments.

RESULTS

A total of 15 key active components included in RRP interacted with 57 core targets related to retinal oxidative damage (such as AKT1, NFE2L2, HMOX1), mainly involved in the AGE-RAGE signaling pathway in diabetic complications, PI3K-AKT signaling pathway and so on. Further studies in vivo found that RRP improved the retinal oxidative damage, increased the content of SOD and GSH, decreased the content of MDA in mouse serum, promoted the expression of p-PI3K, p-AKT, Nrf2, HO-1 and NQO1 proteins in the mouse retina, and inhibited the expression of Nrf2 in the cytoplasm.

CONCLUSION

This study revealed that RRP had a protective effect on oxidative damage of the retina in mice, and might exert anti-oxidative effect by activating the PI3K/Akt/Nrf2 signal pathway. This study provided scientific data for the further development of hospital preparations of RRP, and a good theoretical basis for the clinical application of RRP.

Regulated cell death pathways in the sodium iodate model: Insights and implications for AMD

The sodium iodate (NaIO3) model of increased oxidative stress recapitulates dry AMD features such as patchy RPE loss, secondary photoreceptors, and underlying choriocapillaris death, allowing longitudinal evaluation of the retinal structure. Due to the time- and dose-dependent degeneration observed in diverse animal models, this preclinical model has become one of the most studied models. The events leading to RPE cell death post- NaIO3 injection have been extensively studied, and here we have reviewed different modalities of cell death, including apoptosis, necroptosis, ferroptosis, and pyroptosis with a particular focus on findings associated with in vivo and in vitro NaIO3 studies on RPE cell death. Because the fundamental cause of vision loss in patients with dry AMD is the death of these same cells affected by NaIO3, studies using NaIO3 can provide valuable insights into RPE and photoreceptor cell death mechanisms and can help understand mechanisms behind RPE degeneration in AMD.

Interleukin-17-mediated protective cytokine signaling against degeneration of the retinal pigment epithelium

Injuries to the retinal pigment epithelium (RPE) and outer retina often result in the accumulation of retinal microglia within the subretinal space. These subretinal microglia play crucial roles in inflammation and resolution, but the mechanisms governing their functions are still largely unknown. Our previous research highlighted the protective functions of choroidal γδ T cells in response to RPE injury. In the current study, we employed single-cell RNA sequencing approach to characterize the profiles of immune cells in mouse choroid. We found that γδ T cells were the primary producer of interleukin-17 (IL-17) in the choroid. IL-17 signaled through its receptor on the RPE, subsequently triggering the production of interleukin-6. This cascade of cytokines initiated a metabolic reprogramming of subretinal microglia, enhancing their capacity for lipid metabolism. RPE-specific knockout of IL-17 receptor A led to the dysfunction of subretinal microglia and RPE pathology. Collectively, our findings suggest that responding to RPE injury, the choroidal γδ T cells can initiate a protective signaling cascade that ensures the proper functioning of subretinal microglia.

Multi-Wavelength Photobiomodulation Ameliorates Sodium Iodate-Induced Age-Related Macular Degeneration in Rats

Age-related macular degeneration (AMD) is a global health challenge. AMD causes visual impairment and blindness, particularly in older individuals. This multifaceted disease progresses through various stages, from asymptomatic dry to advanced wet AMD, driven by various factors including inflammation and oxidative stress. Current treatments are effective mainly for wet AMD; the therapeutic options for dry AMD are limited. Photobiomodulation (PBM) using low-energy light in the red-to-near-infrared range is a promising treatment for retinal diseases. This study investigated the effects of multi-wavelength PBM (680, 780, and 830 nm) on sodium iodate-induced oxidatively damaged retinal tissue. In an in vivo rat model of AMD induced by sodium iodate, multi-wavelength PBM effectively protected the retinal layers, reduced retinal apoptosis, and prevented rod bipolar cell depletion. Furthermore, PBM inhibited photoreceptor degeneration and reduced retinal pigment epithelium toxicity. These results suggest that multi-wavelength PBM may be a useful therapeutic strategy for AMD, mitigating oxidative stress, preserving retinal integrity, and preventing apoptosis.

Oxidative Stress-Involved Mitophagy of Retinal Pigment Epithelium and Retinal Degenerative Diseases

The retinal pigment epithelium (RPE) is a highly specialized and polarized epithelial cell layer that plays an important role in sustaining the structural and functional integrity of photoreceptors. However, the death of RPE is a common pathological feature in various retinal diseases, especially in age-related macular degeneration (AMD) and diabetic retinopathy (DR). Mitophagy, as a programmed self-degradation of dysfunctional mitochondria, is crucial for maintaining cellular homeostasis and cell survival under stress. RPE contains a high density of mitochondria necessary for it to meet energy demands, so severe stimuli can cause mitochondrial dysfunction and the excess generation of intracellular reactive oxygen species (ROS), which can further trigger oxidative stress-involved mitophagy. In this review, we summarize the classical pathways of oxidative stress-involved mitophagy in RPE and investigate its role in the progression of retinal diseases, aiming to provide a new therapeutic strategy for treating retinal degenerative diseases. The role of mitophagy in AMD and DR. In AMD, excessive ROS production promotes mitophagy in the RPE by activating the Nrf2/p62 pathway, while in DR, ROS may suppress mitophagy by the FOXO3-PINK1/parkin signaling pathway or the TXNIP-mitochondria-lysosome-mediated mitophagy.

Excessive Thyroid Hormone Signaling Induces Photoreceptor Degeneration in Mice

Rod and cone photoreceptors degenerate in inherited and age-related retinal degenerative diseases, ultimately leading to loss of vision. Thyroid hormone (TH) signaling regulates cell proliferation, differentiation, and metabolism. Recent studies have shown a link between TH signaling and retinal degeneration. This work investigates the effects of excessive TH signaling on photoreceptor function and survival in mice. C57BL/6, Thra1 -/-, Thrb2 -/-, Thrb -/-, and the cone dominant Nrl -/- mice received triiodothyronine (T3) treatment (5-20 μg/ml in drinking water) for 30 d, followed by evaluations of retinal function, photoreceptor survival/death, and retinal stress/damage. Treatment with T3 reduced light responses of rods and cones by 50-60%, compared with untreated controls. Outer nuclear layer thickness and cone density were reduced by ∼18% and 75%, respectively, after T3 treatment. Retinal sections prepared from T3-treated mice showed significantly increased numbers of TUNEL-positive, p-γH2AX-positive, and 8-OHdG-positive cells, and activation of Müller glial cells. Gene expression analysis revealed upregulation of the genes involved in oxidative stress, necroptosis, and inflammation after T3 treatment. Deletion of Thra1 prevented T3-induced degeneration of rods but not cones, whereas deletion of Thrb2 preserved both rods and cones. Treatment with an antioxidant partially preserved photoreceptors and reduced retinal stress responses. This study demonstrates that excessive TH signaling induces oxidative stress/damage and necroptosis, induces photoreceptor degeneration, and impairs retinal function. The findings provide insights into the role of TH signaling in retinal degeneration and support the view of targeting TH signaling for photoreceptor protection.

Oxidative Model of Retinal Neurodegeneration Induced by Sodium Iodate: Morphofunctional Assessment of the Visual Pathway

Sodium iodate (NaIO3) has been shown to cause severe oxidative stress damage to retinal pigment epithelium cells. This results in the indirect death of photoreceptors, leading to a loss of visual capabilities. The aim of this work is the morphological and functional characterization of the retina and the visual pathway of an animal model of retinal neurodegeneration induced by oxidative stress. Following a single intraperitoneal dose of NaIO3 (65 mg/kg) to C57BL/6J mice with a mutation in the Opn4 gene (Opn4-/-), behavioral and electroretinographic tests were performed up to 42 days after administration, as well as retinal immunohistochemistry at day 57. A near total loss of the pupillary reflex was observed at 3 days, as well as an early deterioration of visual acuity. Behavioral tests showed a late loss of light sensitivity. Full-field electroretinogram recordings displayed a progressive and marked decrease in wave amplitude, disappearing completely at 14 days. A reduction in the amplitude of the visual evoked potentials was observed, but not their total disappearance. Immunohistochemistry showed structural alterations in the outer retinal layers. Our results show that NaIO3 causes severe structural and functional damage to the retina. Therefore, the current model can be presented as a powerful tool for the study of new therapies for the prevention or treatment of retinal pathologies mediated by oxidative stress.

Oxidative Stress and Antioxidants in Age-Related Macular Degeneration

Oxidative stress plays a crucial role in aging-related eye diseases, including age-related macular degeneration (AMD), cataracts, and glaucoma. With age, antioxidant reparative capacity decreases, and excess levels of reactive oxygen species produce oxidative damage in many ocular cell types underling age-related pathologies. In AMD, loss of central vision in the elderly is caused primarily by retinal pigment epithelium (RPE) dysfunction and degeneration and/or choroidal neovascularization that trigger malfunction and loss of photo-sensing photoreceptor cells. Along with various genetic and environmental factors that contribute to AMD, aging and age-related oxidative damage have critical involvement in AMD pathogenesis. To this end, dietary intake of antioxidants is a proven way to scavenge free radicals and to prevent or slow AMD progression. This review focuses on AMD and highlights the pathogenic role of oxidative stress in AMD from both clinical and experimental studies. The beneficial roles of antioxidants and dietary micronutrients in AMD are also summarized.

Inhibiting HIF-1 signaling alleviates HTRA1-induced RPE senescence in retinal degeneration

BACKGROUND

Age-related macular degeneration (AMD), characterized by the degeneration of retinal pigment epithelium (RPE) and photoreceptors, is the leading cause of irreversible vision impairment among the elderly. RPE senescence is an important contributor to AMD and has become a potential target for AMD therapy. HTRA1 is one of the most significant susceptibility genes in AMD, however, the correlation between HTRA1 and RPE senescence hasn't been investigated in the pathogenesis of AMD.

METHODS

Western blotting and immunohistochemistry were used to detect HTRA1 expression in WT and transgenic mice overexpressing human HTRA1 (hHTRA1-Tg mice). RT-qPCR was used to detect the SASP in hHTRA1-Tg mice and ARPE-19 cells infected with HTRA1. TEM, SA-β-gal was used to detect the mitochondria and senescence in RPE. Retinal degeneration of mice was investigated by fundus photography, FFA, SD-OCT and ERG. The RNA-Seq dataset of ARPE-19 cells treated with adv-HTRA1 versus adv-NC were analyzed. Mitochondrial respiration and glycolytic capacity in ARPE-19 cells were measured using OCR and ECAR. Hypoxia of ARPE-19 cells was detected using EF5 Hypoxia Detection Kit. KC7F2 was used to reduce the HIF1α expression both in vitro and in vivo.

RESULTS

In our study, we found that RPE senescence was facilitated in hHTRA1-Tg mice. And hHTRA1-Tg mice became more susceptible to NaIO₃ in the development of oxidative stress-induced retinal degeneration. Similarly, overexpression of HTRA1 in ARPE-19 cells accelerated cellular senescence. Our RNA-seq revealed an overlap between HTRA1-induced differentially expressed genes associated with aging and those involved in mitochondrial function and hypoxia response in ARPE-19 cells. HTRA1 overexpression in ARPE-19 cells impaired mitochondrial function and augmented glycolytic capacity. Importantly, upregulation of HTRA1 remarkably activated HIF-1 signaling, shown as promoting HIF1α expression which mainly located in the nucleus. HIF1α translation inhibitor KC7F2 significantly prevented HTRA1-induced cellular senescence in ARPE-19 cells, as well as improved the visual function in hHTRA1-Tg mice treated with NaIO₃.

CONCLUSIONS

Our study showed elevated HTRA1 contributes to the pathogenesis of AMD by promoting cellular senescence in RPE through damaging mitochondrial function and activating HIF-1 signaling. It also pointed out that inhibition of HIF-1 signaling might serve as a potential therapeutic strategy for AMD. Video Abstract.

Role of flavonoids in age-related macular degeneration

A common eye disorder known as age-related macular degeneration (AMD) eventually results in blindness and vision loss. AMD has a complicated and poorly understood aetiology. The main pathological processes associated with AMD include oxidative damage, inflammation, and neovascularization. Flavonoids are naturally occurring bioactive substances with extensive distribution and antioxidant, anti-inflammatory, and neovascularization inhibitory properties. Several in vitro and in vivo AMD-related models pertinent to vision and this ocular ailment have been used to assess the mechanisms of action of various flavonoids. This article will discuss the research progress of flavonoids in AMD, especially the characteristics and mechanism of flavonoids in treating AMD.

Qihuang Granule protects the retinal pigment epithelium from oxidative stress via regulation of the alternative complement pathway

BACKGROUND

Age-related macular degeneration (AMD) is a leading cause of vision loss in elderly people, and dry AMD is the most common type of AMD. Oxidative stress and alternative complement pathway activation may play essential roles in the pathogenesis of dry AMD. There are no available drugs for dry AMD. Qihuang Granule (QHG) is an herbal formula for the treatment of dry AMD, and it achieves a good clinical effect in our hospital. However, its potential mechanism is unclear. Our study investigated the effects of QHG on oxidative stress-associated retinal damage to reveal its underlying mechanism.

METHODS

Oxidative stress models were established using H₂O₂ and NaIO₃ in ARPE-19 cells and C57BL/6 mice. Cell apoptosis and viability were assessed using phase contrast microscopy and flow cytometry, respectively. Alterations in the mouse retinal structure were evaluated using Masson staining and transmission electron microscopy (TEM). The expression of complement factor H (CFH), complement component 3a (C3a) and complement component 5a (C5a) in retinal pigment epithelium (RPE) cells and mice was measured using RT‒PCR, Western blot analysis and ELISA.

RESULTS

Pretreatment with QHG significantly prevented cell apoptosis and disorder of the RPE and inner segment/outer segment (IS/OS) in H₂O₂-treated RPE cells and NaIO₃-injected mice. QHG alleviated mitochondrial damage in mouse RPE cells, as shown by TEM. QHG also promoted CFH expression and inhibited the expression of C3a and C5a.

CONCLUSIONS

The results suggest that QHG protects the retinal pigment epithelium from oxidative stress, likely by regulating the alternative complement pathway.

P2X7 Is Involved in the Mouse Retinal Degeneration via the Coordinated Actions in Different Retinal Cell Types

Adenosine triphosphate (ATP) released from dying cells with high concentrations is sensed as a danger signal by the P2X7 receptor. Sodium iodate (NaIO3) is an oxidative toxic agent, and its retinal toxicity has been used as the model of dry age-related macular degeneration (AMD). In this study, we used NaIO3-treated mice and cultured retinal cells, including BV-2 microglia, 661W photoreceptors, rMC1 Müller cells and ARPE-19 retinal epithelial cells, to understand the pathological action of P2X7 in retinal degeneration. We found that NaIO3 can significantly decrease the photoreceptor function by reducing a-wave and b-wave amplitudes in electroretinogram (ERG) analysis. Optical coherence tomography (OCT) analysis revealed the degeneration of retinal epithelium and ganglion cell layers. Interestingly, P2X7-/- mice were protected from the NaIO3-induced retinopathy and inflammatory NLRP3, IL-1β and IL-6 gene expression in the retina. Hematoxylin and eosin staining indicated that the retinal epithelium was less deteriorated in P2X7-/- mice compared to the WT group. Although P2X7 was barely detected in 661W, rMC1 and ARPE-19 cells, its gene and protein levels can be increased after NaIO3 treatment, leading to a synergistic cytotoxicity of BzATP [2'(3')-O-(4-benzoylbenzoyl)adenosine-5'-triphosphate tri(triethyleneammonium)salt] and NaIO3 administration in ARPE-19 cells. In conclusion, the paracrine action of the ATP/P2X7 axis via cell-cell communication is involved in NaIO3-induced retinal injury. Our results show that P2X7 antagonist might be a potential therapy in inflammation-related retinal degeneration.

Complement C3a receptor inactivation attenuates retinal degeneration induced by oxidative damage

Retinal degeneration causes vision loss and threatens the health of elderly individuals worldwide. Evidence indicates that the activation of the complement system is associated with retinal degeneration. However, the mechanism of complement signaling in retinal degeneration needs to be further studied. In this study, we show that the expression of C3 and C3a receptor (C3ar1) is positively associated with the inflammatory response and retinal degeneration. Genetic deletion of C3 and pharmacological inhibition of C3ar1 resulted in the alleviation of neuroinflammation, prevention of photoreceptor cell apoptosis and restoration of visual function. RNA sequencing (RNA-seq) identified a C3ar1-dependent network shown to regulate microglial activation and astrocyte gliosis formation. Mechanistically, we found that STAT3 functioned downstream of the C3-C3ar1 pathway and that the C3ar1-STAT3 pathway functionally mediated the immune response and photoreceptor cell degeneration in response to oxidative stress. These findings reveal an important role of C3ar1 in oxidative-induced retinal degeneration and suggest that intervention of the C3ar1 pathway may alleviate retinal degeneration.

Sensitivity of the Dorsal-Central Retinal Pigment Epithelium to Sodium Iodate-Induced Damage Is Associated With Overlying M-Cone Photoreceptors in Mice

Purpose

Retinal pigment epithelium (RPE) degeneration is a leading cause of blindness in retinal degenerative diseases, but the mechanism of RPE regional degeneration remains largely unknown. This study aims to investigate the sensitivity of RPE to sodium iodate (SI) injury in the dorsal and ventral visual fields in mice and analyze whether overlaying cone photoreceptors regulate the sensitivity of RPE to SI-induced damage.

Methods

SI was used to induce RPE degeneration in mice. Hematoxylin-eosin staining, immunostaining, and TUNEL assay were used to evaluate retinal degeneration along the dorsal-ventral axis. Flat-mounted and sectional retinal immunostaining were used to analyze the distribution of cones along the dorsoventral axis in C57BL/6, albino, and 129 mice. Electroretinography was used to examine the retinal function.

Results

Dorsal-central RPE was more sensitive to SI-mediated injury along the dorsal-ventral axis in C57BL/6 mice. Compared with the ventral RPE, the dorsal-central RPE was dominantly covered by M cone photoreceptors in these mice. Interestingly, M cone photoreceptor degeneration was followed by dorsal RPE degeneration under a low dose of SI. Furthermore, the sensitivity of dorsal RPE to a low dose of SI was reduced in both albino and 129 mouse strains with dominant mixed cones instead of M cones in the dorsal visual field.

Conclusions

These findings suggest that dorsal-central RPE is more sensitive to SI injury and that SI-induced RPE degeneration could be controlled by modifying the dominant overlying cone population in the mouse dorsal retina, thereby highlighting a potential role of M cones in RPE regional degeneration.

Dependence of Retinal Pigment Epithelium Integrity on the NRF2-Heme Oxygenase-1 Axis

Purpose

Tight junctions (TJs) form the structural basis of retinal pigment epithelium (RPE) barrier functions. Although oxidative stress contributes to age-related macular degeneration, it is unclear how RPE TJ integrity is controlled by redox balance. In this study, we investigated the protective roles of nuclear factor erythroid 2–related factor 2 (NRF2), a transcription factor, and heme oxygenase-1 (HO1), a heme-degrading enzyme encoded by the NRF2 target gene HMOX1.

Methods

ARPE19 cell cultures and mice, including wild-type, Nrf2^−/−, and RPE-specific NRF2-deficient mice, were treated with chemicals that impose oxidative stress or impact heme metabolism. In addition, NRF2 and HO1 expression in ARPE19 cells was knocked down by siRNA. TJ integrity was examined by anti–zonula occludens-1 staining of cultured cells or flatmount RPE tissues from mice. RPE barrier functions were evaluated by transepithelium electrical resistance in ARPE19 cells and immunofluorescence staining for albumin or dextran in eye histological sections.

Results

TJ structures and RPE barrier functions were compromised due to oxidant exposure and NRF2 deficiency but were rescued by HO1 inducer. Furthermore, treatment with HO1 inhibitor or heme precursor is destructive to TJ structures and RPE barrier properties. Interestingly, both NRF2 and HO1 were upregulated under oxidative stress, probably as an adaptive response to mitigate oxidant-inflicted damages.

Conclusions

Our data indicate that the NRF2–HO1 axis protects TJ integrity and RPE barrier functions by driving heme degradation.

Systemic Candida albicans Infection in Mice Causes Endogenous Endophthalmitis via Breaching the Outer Blood-Retinal Barrier

Candida albicans is the leading cause of endogenous fungal endophthalmitis; however, its pathobiology studies are limited. Moreover, the contribution of host factors in the pathogenesis of Candida endophthalmitis remains unclear. In the present study, we developed a murine model of C. albicans endogenous endophthalmitis and investigated the molecular pathobiology of ocular candidiasis and blood-retinal barrier permeability. Our data show that intravenous injection of C. albicans in immunocompetent C57BL/6 mice led to endogenous endophthalmitis without causing mortality, and C. albicans was detected in the eyes at 3 days postinfection and persisted for up to 10 days. The intraocular presence of C. albicans coincided with a decrease in retinal function and increased expression of inflammatory mediators (tumor necrosis factor alpha [TNF-α], interleukin 1β [IL-1β], MIP2, and KC) and antimicrobial peptides (human β-defensins [hBDs] and LL37) in mouse retinal tissue. C. albicans infection disrupted the blood-retinal barrier (BRB) by decreasing the expression of tight junction (ZO-1) and adherens junction (E-cadherin, N/R-cadherin) proteins. In vitro studies using human retinal pigment epithelial (ARPE-19) cells showed time-dependent activation of eIF2α, extracellular signal-related kinase (ERK), and NF-κB signaling and decreased activity of AMP-activated protein kinase (AMPK) leading to the induction of an inflammatory response upon C. albicans infection. Moreover, C. albicans-infected cells exhibited increased cellular permeability coinciding with a reduction in cellular junction proteins. Overall, our study provides new insight into the molecular pathogenesis of C. albicans endogenous endophthalmitis. Furthermore, the experimental models developed in the study can be used to identify newer therapeutic targets or test the efficacy of drugs to treat and prevent fungal endophthalmitis. IMPORTANCE Patients with candidemia often experience endophthalmitis, a blinding infectious eye disease. However, the pathogenesis of Candida endophthalmitis is not well understood. Here, using in vivo and in vitro experimental models, we describe events leading to the invasion of Candida into the eye. We show that Candida from the systemic circulation disrupts the protective blood-retinal barrier and causes endogenous endophthalmitis. Our study highlights an important role of retinal pigment epithelial cells in evoking innate inflammatory and antimicrobial responses toward C. albicans infection. This study allows a better understanding of the pathobiology of fungal endophthalmitis, which can lead to the discovery of novel therapeutic targets to treat ocular fungal infections.

(–)-Epicatechin Provides Neuroprotection in Sodium Iodate-Induced Retinal Degeneration

Oxidative stress, mitochondrial impairment, and pathological amyloid beta (Aβ) deposition are involved in the pathogenesis of dry age-related macular degeneration (AMD). The natural flavonoid (–)-epicatechin (EC) is known to be an antioxidant and neuroprotective compound. Whether EC plays a therapeutic role in AMD is unknown. In this work, we aimed to assess the efficacy and molecular mechanisms of EC against sodium iodate (NaIO₃)-induced retinal degeneration in C57BL/6 mice via bioinformatic, morphological, and functional methods. We demonstrated that EC had no toxic effects on the retina and could ameliorate retinal deformation and thinning. EC treatment prevented outer retinal degeneration, reduced drusen-like deposits, increased b-wave amplitude in electroretinography, blocked retinal gliosis, and increased the number and quality of mitochondria. Importantly, EC increased the protein expression of OPA1 and decreased the expression of PINK1, indicating the role of EC in mitochondrial fusion that impaired by NaIO₃. Moreover, EC downregulated APP and TMEM97 levels, upregulated PGRMC1 levels, and reduced subretinal Aβ accumulation. This study illustrated that EC, which may become a promising therapeutic strategy for AMD, prevented NaIO₃-induced retinal degeneration, and this improvement may be associated with the mitochondrial quality control and the TMEM97/PGRMC1/Aβ signaling pathway.

Complement C3 deficiency alleviates alkylation-induced retinal degeneration in mice

BACKGROUND

It has been found that the extensive use of anticancer drugs containing DNA-alkylating agents not only target cancer cells but also cause retinal inflammation through toxic intermediates. Complement C3 (C3) is a core component of the complement activation pathway, and dysregulation of the complement pathway is involved in several retinal degenerative diseases. However, whether C3 plays a critical role in alkylation-induced retinal degeneration is unclear.

METHODS

Following treatment with the alkylating agent methyl methane sulfonate (MMS), the C3 mRNA and protein level was measured, DNA damage and photoreceptor cell death were assessed in both wild-type (WT) C57BL/6J and C3 knockout (KO) mice.

RESULTS

We determined that complement pathway is activated following MMS treatment, and C3 knockout (KO) increased the rate of photoreceptor cell survival and preserved visual function. The mRNA levels of nuclear erythroid-related factor 2 (Nrf2) and related genes were higher after MMS application in C3 KO mice.

CONCLUSION

In summary, our study found that C3 KO promotes photoreceptor cell survival and activates the Nrf2 signaling pathway in the context of alkylation-induced retinal degeneration.

Ilex paraguariensis Extracts Prevent Oxidative Damage in a Mouse Model of Age-Related Macular Degeneration

Age-related macular degeneration (AMD), a chronic disease of the retina, leads to severe visual loss. AMD affects the retinal pigment epithelium (RPE) and the visual cells (photoreceptors). RPE failure, the first step of this disease, is associated with oxidative stress. Since antioxidants can slow down AMD progression, the intake of foods and drinks rich in antioxidant compounds may reduce retinal damage. Ilex paraguariensis (yerba mate, YM) extracts reduce oxidative damage of RPE cells in vitro as shown in previous study. Here, the effects of YM drinking on RPE and photoreceptor survival after oxidative damage with sodium iodate (NaIO3; SI) in a murine AMD model are described. Funduscopy and histology show that YM treatment prevents RPE and photoreceptor damage. YM also increases the expression of NRF2, the master antioxidant gene, and its effectors HO-1 and SOD2. In mice receiving YM and SI, the antioxidant response is larger than in mice receiving YM or SI alone. The YM drink also increases expression of RPE65, a gene that is involved in the functionality and survival of photoreceptors and RPE cells. The results suggest YM can play an important role in the prevention of retinal damage associated with oxidative stress, such as AMD.

SARM1 Promotes Photoreceptor Degeneration in an Oxidative Stress Model of Retinal Degeneration

SARM1 (sterile alpha and armadillo motif-containing protein) is a highly conserved Toll/IL-1 Receptor (TIR) adaptor with important roles in mediating immune responses. Studies in the brain have shown that SARM1 plays a role in induction of neuronal axon degeneration in response to a variety of injuries. We recently demonstrated that SARM1 is pro-degenerative in a genetic model of inherited retinopathy. This current study aimed to characterise the effect of SARM1 deletion in an alternative model of retinal degeneration (RD) in which the retinal pigment epithelium (RPE) fragments following administration of oxidising agent, sodium iodate (NaIO3), leading to subsequent photoreceptor cell death. Following administration of NaIO3, we observed no apparent difference in rate of loss of RPE integrity in SARM1 deficient mice compared to WT counterparts. However, despite no differences in RPE degeneration, photoreceptor cell number and retinal thickness were increased in Sarm1–/– mice compared to WT counterparts. This apparent protection of the photoreceptors in SARM1 deficient mice is supported by an observed decrease in pro-apoptotic caspase-3 in the photoreceptor layer of Sarm1–/– mice compared to WT. Together these data indicate a pro-degenerative role for SARM1 in the photoreceptors, but not in the RPE, in an oxidative stress induced model of retinal degeneration consistent with its known degenerative role in neurons in a range of neurodegenerative settings.

Comparison between sodium iodate and lipid peroxide murine models of age-related macular degeneration for drug evaluation-a narrative review

Objective

In this review, non-transgenic models of age-related macular degeneration (AMD) are discussed, with focuses on murine retinal degeneration induced by sodium iodate and lipid peroxide (HpODE) as preclinical study platforms.

Background

AMD is the most common cause of vision loss in a world with an increasingly aging population. The major phenotypes of early and intermediate AMD are increased drusen and autofluorescence, Müller glia activation, infiltrated subretinal microglia and inward moving retinal pigment epithelium cells. Intermediate AMD may progress to advanced AMD, characterized by geography atrophy and/or choroidal neovascularization. Various transgenic and non-transgenic animal models related to retinal degeneration have been generated to investigate AMD pathogenesis and pathobiology, and have been widely used as potential therapeutic evaluation platforms.

Methods

Two retinal degeneration murine models induced by sodium iodate and HpODE are described. Distinct pathological features and procedures of these two models are compared. In addition, practical protocol and material preparation and assessment methods are elaborated.

Conclusion

Retina degeneration induced by sodium iodate and HpODE in mouse eye resembles many clinical aspects of human AMD and complimentary to the existent other animal models. However, standardization of procedure and assessment protocols is needed for preclinical studies. Further studies of HpODE on different routes, doses and species will be valuable for the future extensive use. Despite many merits of murine studies, differences between murine and human should be always considered.

Sodium-Iodate Injection Can Replicate Retinal Degenerative Disease Stages in Pigmented Mice and Rats: Non-Invasive Follow-Up Using OCT and ERG

Purpose: The lack of suitable animal models for (dry) age-related macular degeneration (AMD) has hampered therapeutic research into the disease, so far. In this study, pigmented rats and mice were systematically injected with various doses of sodium iodate (SI). After injection, the retinal structure and visual function were non-invasively characterized over time to obtain in-depth data on the suitability of these models for studying experimental therapies for retinal degenerative diseases, such as dry AMD. Methods: SI was injected into the tail vein (i.v.) using a series of doses (0–70 mg/kg) in adolescent C57BL/6J mice and Brown Norway rats. The retinal structure and function were assessed non-invasively at baseline (day 1) and at several time points (1–3, 5, and 10-weeks) post-injection by scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT), and electroretinography (ERG). Results: After the SI injection, retinal degeneration in mice and rats yielded similar results. The lowest dose (10 mg/kg) resulted in non-detectable structural or functional effects. An injection with 20 mg/kg SI did not result in an evident retinal degeneration as judged from the OCT data. In contrast, the ERG responses were temporarily decreased but returned to baseline within two-weeks. Higher doses (30, 40, 50, and 70 mg/kg) resulted in moderate to severe structural RPE and retinal injury and decreased the ERG amplitudes, indicating visual impairment in both mice and rat strains. Conclusions: After the SI injections, we observed dose-dependent structural and functional pathological effects on the retinal pigment epithelium (RPE) and retina in the pigmented mouse and rat strains that were used in this study. Similar effects were observed in both species. In particular, a dose of 30 mg/kg seems to be suitable for future studies on developing experimental therapies. These relatively easily induced non-inherited models may serve as useful tools for evaluating novel therapies for RPE-related retinal degenerations, such as AMD.

Deficiency of thyroid hormone receptor protects retinal pigment epithelium and photoreceptors from cell death in a mouse model of age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of vision loss in the elderly. Progressive dystrophy of the retinal pigment epithelium (RPE) and photoreceptors is the characteristic of dry AMD, and oxidative stress/damage plays a central role in the pathogenic lesion of the disease. Thyroid hormone (TH) regulates cell growth, differentiation, and metabolism, and regulates development/function of photoreceptors and RPE in the retina. Population-/patient-based studies suggest an association of high free-serum TH levels with increased risk of AMD. We recently showed that suppressing TH signaling by antithyroid treatment reduces cell damage/death of the RPE and photoreceptors in an oxidative-stress/sodium iodate (NaIO₃)-induced mouse model of AMD. This work investigated the effects of TH receptor (THR) deficiency on cell damage/death of the RPE and photoreceptors and the contribution of the receptor subtypes. Treatment with NaIO₃ induced RPE and photoreceptor cell death/necroptosis, destruction, and oxidative damage. The phenotypes were significantly diminished in Thrα1^−/−, Thrb^−/−, and Thrb2^−/− mice, compared with that in the wild-type (C57BL/6 J) mice. The involvement of the receptor subtypes varies in the RPE and retina. Deletion of Thrα1 or Thrb protected RPE, rods, and cones, whereas deletion of Thrb2 protected RPE and cones but not rods. Gene-expression analysis showed that deletion of Thrα1 or Thrb abolished/suppressed the NaIO₃-induced upregulation of the genes involved in cellular oxidative-stress responses, necroptosis/apoptosis signaling, and inflammatory responses. In addition, THR antagonist effectively protected ARPE-19 cells and hRPE cells from NaIO₃-induced cell death. This work demonstrates the involvement of THR signaling in cell damage/death of the RPE and photoreceptors after oxidative-stress challenge and the receptor-subtype contribution. Findings from this work support a role of THR signaling in the pathogenesis of AMD and the strategy of suppressing THR signaling locally in the retina for protection of the RPE/retina in dry AMD.

Rescue of photoreceptor with human mesenchyme stem cell and human mesenchyme stem cell expressing erythropoietin in total degeneration of retina animal model

Purpose:

This study aimed to investigate the efficacy of human-derived umbilical cord mesenchymal stem cells (HDUMSC) and human-derived umbilical cord mesenchymal stem cells expressing erythropoietin (HDUMSC-EPO) to rescue total degenerated retina in a rat model.

Methods:

The study included four treatment groups, namely negative control using normal saline (HBSS) injection, positive control using sodium iodide 60 mg/kg (SI), SI treated with HDUMSC, and SI treated with HDUMSC-EPO given via subretinal and intravenous routes, to test the efficacy of retinal regeneration following SI-induced retinal degeneration. Retinal function in both phases was tested via electroretinography (ERG) and histological staining examining the outer nuclear layer (ONL).

Results:

There was a statistically significant result (P < 0.05) in the SI treated with HDUMSC-EPO only when comparing day 11 (mean = 23.6 μv), day 18 (mean = 25.2 μv), day 26 (mean = 26.3 μv), and day 32 (mean = 28.2 μv) to the b-wave ERG on day 4 rescue injection day (mean = 12.5 μv). The SI treated with HDUMSC-EPO showed significant improvement in b-wave ERG readings in the Sprague–Dawley (SD) rat but did not restore baseline readings prior to degeneration (day 0). Both treated groups’ ONL thicknesses did not show significant changes compared to the negative control group (HBSS) following rescue therapy.

Conclusion:

Total retinal degeneration following intravenous SI injection was observed at 60 mg/kg. SI treated with HDUMSC and HDUMSC-EPO showed no regenerative potential compared to baseline in SI-induced total retina degeneration on ERG or histology, whereas SI treated with HDUMSC-EPO group showed a substantial increase in b-wave ERG amplitude over time.

Inhibition of DUSP6 Activates Autophagy and Rescues the Retinal Pigment Epithelium in Sodium Iodate-Induced Retinal Degeneration Models In Vivo and In Vitro

Autophagy plays a protective role in the retinal pigment epithelium (RPE) by eliminating damaged organelles in response to reactive oxygen species (ROS). Dual-specificity protein phosphatase 6 (DUSP6), which belongs to the DUSP subfamily, works as a negative-feedback regulator of the extracellular signal-regulated kinase (ERK) pathway. However, the complex interplay between DUSP6 and autophagy induced by ROS in RPE is yet to be investigated. To investigate the relationship between DUSP6 and autophagy, we exposed the ARPE-19 cell line and C57BL/6N mice to sodium iodate (NaIO₃) as an oxidative stress inducer. Our data showed that the inhibition of DUSP6 activity promotes autophagy flux through the ERK pathway via the upregulation of immunoblotting expression in ARPE-19 cells. Live imaging showed a significant increase in autophagic flux activities, which suggested the restoration autophagy after treatment with the DUSP6 inhibitor. Furthermore, the mouse RPE layer exhibited an irregular structure and abnormal deposits following NaIO₃ injection. The retina layer was recovered after being treated with DUSP6 inhibitor; this suggests that DUSP6 inhibitor can rescue retinal damage by restoring the mouse retina’s autophagy flux. This study suggests that the upregulation of DUSP6 can cause autophagy flux malfunctions in the RPE. The DUSP6 inhibitor can restore autophagy induction, which may serve as a potential therapeutic approach for retinal degeneration disease.

Heterochromatin inhibits cGAS and STING during oxidative stress-induced retinal pigment epithelium and retina degeneration

Age-related macular degeneration (AMD) is a leading cause of blindness characterized by degeneration of retina pigment epithelium (RPE) and photoreceptors in the macular region. Activation of the innate immune cGAS-STING signaling has been detected in RPE of dry AMD patients, but the regulatory basis is largely unexplored. Heterochromatin is a highly compact, transcription inert chromatin status. We have recently shown that heterochromatin is required for RPE survival through epigenetically silencing p53-mediated apoptosis signaling. Here, we found that cGAS and STING were dose-dependently upregulated in mouse RPE and retina during oxidative injury, correlated with decreased chromatin compaction in their gene loci. Genetic or pharmaceutical disruption of heterochromatin leads to elevated cGAS and STING expression and enhanced inflammatory response in oxidative stress-induced RPE and retina degeneration. In contrast, application of methotrexate (MTX), a recently identified heterochromatin-promoting drug, inhibits cGAS and STING in both RPE and retina, attenuates RPE/retina degeneration and inflammation. Further, we show that intact heterochromatin is required for MTX to repress cGAS and STING. Together, we demonstrated an unrevealed regulatory function of heterochromatin on cGAS and STING expression and provide potential new therapeutic strategy for AMD treatment.

Fine Tuning of an Oxidative Stress Model with Sodium Iodate Revealed Protective Effect of NF-κB Inhibition and Sex-Specific Difference in Susceptibility of the Retinal Pigment Epithelium

Oxidative stress of the retinal pigment epithelium (RPE) is a major risk factor for age-related macular degeneration (AMD). As a dry AMD model via oxidative stress, sodium iodate (NaIO₃), which is primarily toxic to the RPE, has often been used at a high dose to cause RPE death for studying photoreceptor degeneration. Thus, characterization of RPE damage by a low dose of NaIO₃ is still limited. To quantify RPE damage caused by NaIO₃ in mice, we recently developed a morphometric method using RPE flat-mounts. Here, we report that NaIO₃ has a narrow range of dose–effect correlation at 11–18 mg/kg body weight in male C57BL/6J mice. We evaluated the usefulness of our quantification method in two experimental settings. First, we tested the effect of NF-κB inhibition on NaIO₃-induced RPE damage in male C57BL/6J mice. IKKβ inhibitor BAY 651942 suppressed upregulation of NF-κB targets and protected the RPE from oxidative stress. Second, we tested sex-specific differences in NaIO₃-induced RPE damage in C57BL/6J mice using a low dose near the threshold. NaIO₃ caused more severe RPE damage in female mice than in male mice. These results demonstrate the usefulness of the quantification method and the importance of fine-tuning of the NaIO₃ dose. The results also show the therapeutic potential of IKKβ inhibition for oxidative stress-related RPE diseases, and reveal previously-unrecognized sex-specific differences in RPE susceptibility to oxidative stress.

TMEM97 ablation aggravates oxidant-induced retinal degeneration

The retinal pigment epithelium (RPE) is critical to the survival of the overlying photoreceptors. Subject to light exposure and active metabolism, the RPE and photoreceptors are particularly susceptible to oxidative damage that plays an important part in age-related macular degeneration (AMD). Recent meta-analyses identified TMEM97 as a new putative AMD risk locus, though it is yet to be functionally verified. The role of TMEM97 in the retina and RPE is not known. Here we investigated TMEM97 function using the sodium iodate model of oxidant-induced retinal degeneration in TMEM97 knockout (KO) mice. We found markedly increased reactive oxygen species (ROS) and loss of photoreceptos in TMEM97 KO mouse retinas relative to wild type (WT) controls. In vitro, sodium iodate treatment of CRISPR-mediated TMEM97 KO RPE cells resulted in diminished abundance of the master antioxidant transcription factor NRF2 and its target gene product SOD2, the mitochondrial superoxide dismutase, as well as elevated ROS and apoptosis markers. Moreover, TMEM97 KO affected proteins key to mitochondrial and lysosomal stability and impeded autophagy flux. These findings suggest that the absence of TMEM97 in RPE cells disturbs redox-balancing systems, thereby heightening oxidative stress. As TMEM97 is a druggable target, this study may inspire interest in basic and translational research in the context of retinal degeneration.

Release of Iron-Loaded Ferritin in Sodium Iodate-Induced Model of Age Related Macular Degeneration: An In-Vitro and In-Vivo Study

To evaluate the role of iron in sodium iodate (NaIO3)-induced model of age-related macular degeneration (AMD) in ARPE-19 cells in-vitro and in mouse models in-vivo. ARPE-19 cells, a human retinal pigment epithelial cell line, was exposed to 10 mM NaIO3 for 24 h, and the expression and localization of major iron modulating proteins was evaluated by Western blotting (WB) and immunostaining. Synthesis and maturation of cathepsin-D (cat-D), a lysosomal enzyme, was evaluated by quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR) and WB, respectively. For in-vivo studies, C57BL/6 mice were injected with 40 mg/kg mouse body weight of NaIO3 intraperitoneally, and their retina was evaluated after 3 weeks as above. NaIO3 induced a 10-fold increase in ferritin in ARPE-19 cells, which co-localized with LC3II, an autophagosomal marker, and LAMP-1, a lysosomal marker. A similar increase in ferritin was noted in retinal lysates and retinal sections of NaIO3-injected mice by WB and immunostaining. Impaired synthesis and maturation of cat-D was also noted. Accumulated ferritin was loaded with iron, and released from retinal pigmented epithelial (RPE) cells in Perls' and LAMP-1 positive vesicles. NaIO3 impairs lysosomal degradation of ferritin by decreasing the transcription and maturation of cat-D in RPE cells. Iron-loaded ferritin accumulates in lysosomes and is released in lysosomal membrane-enclosed vesicles to the extracellular milieu. Accumulation of ferritin in RPE cells and fusion of ferritin-containing vesicles with adjacent photoreceptor cells is likely to create an iron overload, compromising their viability. Moreover, reduced activity of cat-D is likely to promote accumulation of other cellular debris in lysosomal vesicles, contributing to AMD-like pathology.

Electrophysiologic and Morphologic Strain Differences in a Low-Dose NaIO3-Induced Retinal Pigment Epithelium Damage Model

Purpose

We aimed to explore differences in the NaIO₃-elicited responses of retinal pigment epithelium (RPE) and other retinal cells associated with mouse strains and dosing regimens.

Methods

One dose of NaIO₃ at 10 or 15 mg/kg was given intravenously to adult male C57BL/6J and 129/SV-E mice. Control animals were injected with PBS. Morphologic and functional changes were characterized by spectral domain optical coherence tomography, electroretinography, histologic, and immunofluorescence techniques.

Results

Injection with 10 mg/kg of NaIO₃ did not cause consistent RPE or retinal changes in either strain. Administration of 15 mg/kg of NaIO₃ initially induced a large transient increase in scotopic electroretinography a-, b-, and c-wave amplitudes within 12 hours of injection, followed by progressive structural and functional degradation at 3 days after injection in C57BL/6J mice and at 1 week after injection in 129/SV-E mice. RPE cell loss occurred in a large posterior-central lesion with a ring-like transition zone of abnormally shaped cells starting 12 hours after NaIO₃ treatment.

Conclusions

NaIO₃ effects depended on the timing, dosage, and mouse strain. The RPE in the periphery was spared from damage compared with the central RPE. The large transient increase in the electroretinography was remarkable.

Translational Relevance

This study is a phase T1 translational research study focusing on the development and validation of a mouse model of RPE damage. It provides a detailed foundation for future research, informing choices of mouse strain, dosage, and time points to establish NaIO₃-induced RPE damage.

Quercetin Alleviates the Accumulation of Superoxide in Sodium Iodate-Induced Retinal Autophagy by Regulating Mitochondrial Reactive Oxygen Species Homeostasis through Enhanced Deacetyl-SOD2 via the Nrf2-PGC-1α-Sirt1 Pathway

Oxidative damage of retinal pigment epithelium (RPE) cells plays an important role in the pathogenesis of blindness-related diseases, such as age-related macular degeneration (AMD). Quercetin, a bioactive flavonoid compound, has been shown to have a protective effect against oxidative stress-induced cell apoptosis and inflammation in RPE cells; however, the detailed mechanism underlying this protective effect is unclear. Therefore, the aim of this study was to investigate the regulatory mechanism of quercetin in a sodium iodate (NaIO₃)-induced retinal damage. The clinical features of the mice, the production of oxidative stress, and the activity of autophagy and mitochondrial biogenesis were examined. In the mouse model, NaIO₃ treatment caused changes in the retinal structure and reduced pupil constriction, and quercetin treatment reversed the oxidative stress-related pathology by decreasing the level of superoxide dismutase 2 (SOD2) while enhancing the serum levels of catalase and glutathione. The increased level of reactive oxygen species in the NaIO₃-treated ARPE19 cells was improved by treatment with quercetin, accompanied by a reduction in autophagy and mitochondrial biogenesis. Our findings indicated that the effects of quercetin on regulating the generation of mtROS were dependent on increased levels of deacetyl-SOD2 through the Nrf2-PGC-1α-Sirt1 signaling pathway. These results demonstrated that quercetin may have potential therapeutic efficacy for the treatment of AMD through the regulation of mtROS homeostasis.

Protective effect of rapamycin in models of retinal degeneration

Age-related macular degeneration (AMD) is a complex retinal disease with no viable treatment strategy. The causative mechanistic pathway for this disease is not yet clear. Therefore, it is highly warranted to screen effective drugs to treat AMD. Rapamycin are known to inhibit inflammation and has been widely used in the clinic as an immunosuppressant. This study aimed to investigate the protective effect of rapamycin on the AMD retinal degeneration model. The AMD models were established by injection of 35 mg/kg sodium iodate (NaIO₃) into the tail vein. Then the treated mice intraperitoneally received rapamycin (2 mg/kg) once a day. The histomorphological analysis showed that rapamycin could inhibit retinal structure damage and apoptosis. Experiments revealed that rapamycin significantly attenuated inflammatory response and oxidative stress. Our experimental results demonstrated that rapamycin has protected the retinal against degeneration induced by NaIO₃. The therapeutic effect was more significant after 7 days of treatment. Therefore, our study potentially provides a powerful experimental support for the treatment of AMD.

The retinal pigment epithelium: Development, injury responses, and regenerative potential in mammalian and non-mammalian systems

Diseases that result in retinal pigment epithelium (RPE) degeneration, such as age-related macular degeneration (AMD), are among the leading causes of blindness worldwide. Atrophic (dry) AMD is the most prevalent form of AMD and there are currently no effective therapies to prevent RPE cell death or restore RPE cells lost from AMD. An intriguing approach to treat AMD and other RPE degenerative diseases is to develop therapies focused on stimulating endogenous RPE regeneration. For this to become feasible, a deeper understanding of the mechanisms underlying RPE development, injury responses and regenerative potential is needed. In mammals, RPE regeneration is extremely limited; small lesions can be repaired by the expansion of adjacent RPE cells, but large lesions cannot be repaired as remaining RPE cells are unable to functionally replace lost RPE tissue. In some injury paradigms, RPE cells proliferate but do not regenerate a morphologically normal monolayer, while in others, proliferation is pathogenic and results in further disruption to the retina. This is in contrast to non-mammalian vertebrates, which possess tremendous RPE regenerative potential. Here, we discuss what is known about RPE formation during development in mammalian and non-mammalian vertebrates, we detail the processes by which RPE cells respond to injury, and we describe examples of RPE-to-retina and RPE-to-RPE regeneration in non-mammalian vertebrates. Finally, we outline barriers to RPE-dependent regeneration in mammals that could potentially be overcome to stimulate a regenerative response from the RPE.

HO-1-mediated ferroptosis as a target for protection against retinal pigment epithelium degeneration

Oxidative stress-mediated retinal pigment epithelium (RPE) degeneration plays a vital role in retinal degeneration with irreversible visual impairment, most notably in age-related macular degeneration (AMD), but a key pathogenic factor and the targeted medical control remain controversial and unclear. In this work, by sophisticated high-throughput sequencing and biochemistry investigations, the major pathologic processes during RPE degeneration in the sodium iodate-induced oxidative stress model has been identified to be heme oxygenase-1 (HO-1)-regulated ferroptosis, which is controlled by the Nrf2–SLC7A11–HO-1 hierarchy, through which ferrous ion accumulation and lethal oxidative stress cause RPE death and subsequently photoreceptor degeneration. By direct knockdown of HO-1 or using HO-1 inhibitor ZnPP, the specific inhibition of HO-1 overexpression has been determined to significantly block RPE ferroptosis. In mice, treatment with ZnPP effectively rescued RPE degeneration and achieved superior therapeutic effects: substantial recovery of the retinal structure and visual function. These findings highlight that targeting HO-1-mediated RPE ferroptosis could serve as an effectively retinal-protective strategy for retinal degenerative diseases prevention, including AMD.

Protective Effect of Quercetin on Sodium Iodate-Induced Retinal Apoptosis through the Reactive Oxygen Species-Mediated Mitochondrion-Dependent Pathway

Age-related macular degeneration (AMD) leads to gradual central vision loss and is the third leading cause of irreversible blindness worldwide. The underlying mechanisms for this progressive neurodegenerative disease remain unclear and there is currently no preventive treatment for dry AMD. Sodium iodate (NaIO₃) has been reported to induce AMD-like retinal pathology in mice. We established a mouse model for AMD to evaluate the effects of quercetin on NaIO₃-induced retinal apoptosis, and to investigate the pertinent underlying mechanisms. Our in vitro results indicated that quercetin protected human retinal pigment epithelium (ARPE-19) cells from NaIO₃-induced apoptosis by inhibiting reactive oxygen species production and loss of mitochondrial membrane potential as detected by Annexin V-FITC/PI flow cytometry. We also evaluated the relative expression of proteins in the apoptosis pathway. Quercetin downregulated the protein expressions of Bax, cleaved caspase-3, and cleaved PARP and upregulated the expression of Bcl-2 through reduced PI3K and pAKT expressions. Furthermore, our in vivo results indicated that quercetin improved retinal deformation and increased the thickness of both the outer nuclear layer and inner nuclear layer, whereas the expression of caspase-3 was inhibited. Taken together, these results demonstrate that quercetin could protect retinal pigment epithelium and the retina from NaIO₃-induced cell apoptosis via reactive oxygen species-mediated mitochondrial dysfunction, involving the PI3K/AKT signaling pathway. This suggests that quercetin has the potential to prevent and delay AMD and other retinal diseases involving NaIO₃-mediated apoptosis.

Human Dental Pulp Stem Cells (DPSCs) Therapy in Rescuing Photoreceptors and Establishing a Sodium Iodate-Induced Retinal Degeneration Rat Model

BACKGROUND

Different methods have been used to inject stem cells into the eye for research. We previously explored the intravitreal route. Here, we investigate the efficacy of intravenous and subretinal-transplanted human dental pulp stem cells (DPSCs) in rescuing the photoreceptors of a sodium iodate-induced retinal degeneration model.

METHODS

Three groups of Sprague Dawley rats were used: intervention, vehicle group and negative control groups (n = 6 in each). Intravenous injection of 60 mg/kg sodium iodate (day 0) induced retinal degeneration. On day 4 post-injection of sodium iodate, the rats in the intervention group received intravenous DPSC and subretinal DPSC in the right eye; rats in the vehicle group received subretinal Hank's balance salt solution and intravenous normal saline; while negative control group received nothing. Electroretinogram (ERG) was performed to assess the retinal function at day 0 (baseline), day 4, day 11, day 18, day 26, and day 32. By the end of the study at day 32, the rats were euthanized, and both their enucleated eyes were sent for histology.

RESULTS

No significant difference in maximal ERG a-wave (p = 0.107) and b-wave, (p = 0.153) amplitude was seen amongst the experimental groups. However, photopic 30 Hz flicker amplitude of the study eye showed significant differences in the 3 groups (p = 0.032). Within the intervention group, there was an improvement in 30 Hz flicker ERG response of all 6 treated right eyes, which was injected with subretinal DPSC; while the 30 Hz flicker ERG of the non-treated left eyes remained flat. Histology showed improved outer nuclear layer thickness in intervention group; however, findings were not significant compared to the negative and vehicle groups.

CONCLUSION

Combination of subretinal and intravenous injection of DPSCs may have potential to rescue cone function from a NaIO₃-induced retinal injury model.

Naringenin protects RPE cells from NaIO3-induced oxidative damage in vivo and in vitro through up-regulation of SIRT1

BACKGROUND

Dry age-related macular degeneration (dAMD) leads to serious burden of visual impairment and there is no definitive treatment. Previous studies have showed that naringenin (NAR) significantly increased electroretinography (ERG) c-wave in sodium iodate (NaIO₃)-treated rats and viability of NaIO₃-treated ARPE-19 cells. But the underlying mechanism is still unknown.

PURPOSE

We tested the hypothesis that anti-oxidation mediated by Sirtuin 1 (SIRT1) was important to the protective effect of NAR on dAMD.

STUDY DESIGN/METHODS

NaIO₃-induced mice retinopathy and ARPE-19 cells injury models were established. In vivo, the protective effect of NAR eye drops on retina was evaluated by flash ERG (FERG) recording and histopathological examination. In vitro, viability of ARPE-19 cells, and the levels of lactic dehydrogenase (LDH), reactive oxygen species (ROS) and carbonyl protein were detected. Protein expression of SIRT1 was analyzed by immunochemical staining, immunofluorescence and western blotting.

RESULTS

NAR eye drops improved retinal function and morphology and normalized the protein expression of SIRT1 in mice exposed to NaIO₃. NAR promoted the survival of ARPE-19 cells in a concentration-dependent manner. NAR up-regulated SIRT1 protein expression, and decreased levels of ROS and carbonyl protein. Moreover, EX527, a selective inhibitor of SIRT1, abolished the effects of NAR on the cell viability and ROS. In addition, SRT1720, a selective agonist of SIRT1, improved the viability of cells and suppressed the production of ROS.

CONCLUSION

Our findings indicate that SIRT1-mediated anti-oxidation contributes to the protective effect of NAR eye drops on dAMD.

Mammalian Retinal Cell Quantification

Normal retina and its cell layers are essential for processing visual stimuli, and loss of its integrity has been documented in many disease processes. The numbers and the axonal processes of retinal ganglion cells are reduced substantially in glaucoma, leading to vision loss and blindness. Similarly, selective loss of photoreceptors in age-related macular degeneration and hereditary retinal dystrophies also results in the compromise of visual acuity. Development of genetically modified mice has led to increased understanding of the pathogenesis of many retinal diseases. Similarly, in this digital era, usage of modalities to quantify the retinal cell loss has grown exponentially leading to a better understanding of the suitability of animal models to study human retinal diseases. These quantification modalities provide valuable quantifiable data in studying pathogenesis and disease progression. This review will discuss the immunohistochemical markers for various retinal cells, available automated tools to quantify retinal cells, and present an example of retinal ganglion cell quantification using HALO image analysis platform. Additionally, we briefly review retinal cell types and subtypes, salient features of retina in various laboratory animal species, and a few of the main disease processes that affect retinal cell numbers in humans.

Protective Effects of Fermented Paprika (Capsicum annuum L.) on Sodium Iodate-Induced Retinal Damage

Diseases of the outer retina, including age-related macular degeneration (AMD), are major cause of permanent visual damage. The pathogenesis of AMD involves oxidative stress and damage of the retinal pigment epithelium. Capsicum annuum L. (paprika) fruits have been known as a source of vitamins, carotenoids, phenolic compounds, and metabolites with a well-known antioxidant activity, which have positive effects on human health and protection against AMD and cataracts. In this study, we investigated whether paprika (fermented (FP), yellow, and orange colored) fermented with Lactobacillus (L.) plantarum could increase the protective effect of retinal degeneration using in vitro and in vivo models. FP significantly increased cell survival and reduced levels of lactate dehydrogenase as well as intracellular reactive oxygen species (ROS) increase in SI (sodium iodate, NaIO₃)-treated human retinal pigment epithelial (ARPE-19) cells. We developed a model of retinal damage in C57BL/6 mice using SI (30 mg/kg) via intraperitoneal injection. Seven days after SI administration, deformation and a decrease in thickness were observed in the outer nuclear layer, but improved by FP treatment. FP administration protected the SI-mediated reduction of superoxide dismutase and glutathione levels in the serum and ocular tissues of mice. The overproduction of cleaved poly(ADP-Ribose) Polymerase (PARP)1, caspase-3 and -8 proteins were significantly protected by FP in SI-treated cells and ocular tissues. In addition, we evaluated the potentiating effects of FP on antioxidants and their underlying mechanisms in RAW 264.7 cells. Lipopolysaccharide (LPS)-induced nitrite increase was markedly blocked by FP treatment in RAW 264.7 cells. Furthermore, FP reduced LPS-induced inducible nitric oxide synthase and cyclooxygenase-2 activation. The FP also enhanced the inhibitory effects on mitogen activated kinase signaling protein activation in ARPE-19 and RAW 264.7 cells and ocular tissues. There was no significant difference in total phenol and flavonoid content in paprika by fermentation, but the vitamin C content was increased in orange colored paprika, and protective effect against oxidative stress-mediated retinal damage was enhanced after fermentation. These results suggest that FP may be a potential candidate to protect against retinal degenerative diseases through the regulation of oxidative stress.

Effect of autologous growth factors on apoptosis and thickness of the outer nuclear layer in an experimental retinal degeneration model

Retinal pigment epithelium and photoreceptor cells are a microenvironment where 90 different peptides are synthesized for transduction, visual cycle, intracellular electron transport chain, and removal of metabolic wastes. Depending on the inheritance pattern, either mutant proteins accumulate inside the cells or the energy cycle is disrupted. Disruption of homeostasis causes the cells to switch to the dormant phase; if the improper conditions last longer, then apoptosis eventually develops resulting in a loss of visual function. In neural tissues, growth factors such as neural growth factor, brain-derived neurotrophic factor, ciliary neurotrophic factor, and insulin-like growth factor are regulatory peptides for intracellular energy cycle and intracellular digestion. In this study, it has been shown histopathologically that autologous growth factors can prevent apoptosis and prevent loss of outer retinal thickness in the retinal degeneration model created with sodium iodate.