Retinal Apoptosis Research Articles

Engineered mesenchymal stem cell-derived small extracellular vesicles for diabetic retinopathy therapy through HIF-1α/EZH2/PGC-1α pathway

Diabetic retinopathy (DR) is a leading cause of blindness worldwide with limited treatment options. Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) hold promise as a cell-free therapy for retinal diseases. In this study, we present evidence that the intravitreal injection of MSC-sEVs improved retinal function and alleviated retinal apoptosis, inflammation, and angiogenesis in both db/db mice and streptozotocin-induced diabetic rats. Mechanistically, hyperglycemia-induced activation of hypoxia-inducible factor-1α (HIF-1α) inhibited the tripartite motif 21 (TRIM21)-mediated ubiquitination and degradation of enhancer of zeste homologue 2 (EZH2), ultimately resulting in the downregulation of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) through EZH2-induced methylation modification. The presence of miR-5068 and miR-10228 in MSC-sEVs targeted the HIF-1α/EZH2/PGC-1α pathway. The blockade of miR-5068 and miR-10228 abolished the retinal therapeutic effects of MSC-sEVs. Additionally, we engineered MSC-sEVs with elevated levels of miR-5068 and miR-10228 to enhance retinal repair efficiency. Together, our findings provide novel insights into the mechanism underlying DR progress and highlight the potential of MSC-sEVs, especially engineered MSC-sEVs, as a therapeutic option for DR.

Combination Therapy with N-Acetylserotonin and Aflibercept Activated the Akt/Nrf2 Pathway to Inhibit Apoptosis and Oxidative Stress in Rats with Retinal Ischemia–Reperfusion Injury

Purpose N-acetylserotonin (NAS) can reduce retinal ischemia–reperfusion injury (RIRI) by inhibiting the TLR4/NF-κB/NLRP3 signaling pathway. Aflibercept is an anti-VEGF drug used to treat a variety of eye diseases. This study was performed to investigate the effect of combination therapy with N-acetylserotonin and aflibercept on RIRI and its mechanism. Methods The RIRI model was established by elevating the intraocular pressure. H&E staining was used to observe the pathological changes in the retinal tissue. Cell apoptosis was evaluated by TUNEL. The expression of cleaved caspase-3 in the retina was detected by immunofluorescence and western blotting. The levels of SOD, GSH-Px, and MDA in retinal tissue were measured by ELISA. The protein expression of cytoplasmic Nrf2, nuclear Nrf2, HO-1, Akt, and p-Akt was determined by western blotting. Results The results showed that combination therapy with NAS and aflibercept significantly alleviated retinal histopathological damage, decreased retinal thickness (from 335.49 ± 30.50 µm to 226.16 ± 17.20 µm, p < 0.001) and the rate of retinal apoptosis (from 28.27 ± 0.39% to 7.87 ± 0.19%, p < 0.001), and downregulated protein expression (from 2.42 ± 0.03 to 1.39 ± 0.03, p < 0.001) and positive expression (from 31.88 ± 0.52 to 25.36 ± 0.58, p < 0.001) of cleaved caspase-3. In addition, combination therapy with NAS and aflibercept also upregulated the levels of SOD (from 20.31 ± 0.18 to 29.66 ± 0.83, p < 0.001) and GSH-Px (from 13.62 ± 0.36 to 19.31 ± 0.82, p < 0.001) and downregulated the level of MDA (from 0.51 ± 0.01 to 0.41 ± 0.01, p < 0.001) to inhibit oxidative stress. Finally, combination therapy with NAS and aflibercept increased the protein expression of cytoplasmic Nrf2 (from 0.10 ± 0.002 to 0.85 ± 0.01, p < 0.001), nuclear Nrf2 (from 0.43 ± 0.01 to 0.88 ± 0.04, p < 0.001), and HO-1 (from 0.45 ± 0.03 to 0.91 ± 0.04, p < 0.001) and the p-Akt/Akt ratio (from 0.45 ± 0.02 to 0.81 ± 0.07, p < 0.001). Conclusions Overall, combination therapy with NAS and aflibercept attenuated RIRI, and its mechanism may be related to inhibiting apoptosis and oxidative stress and activating the Akt/Nrf2 pathway.

Retinal apoptosis and the effect of tyrosine kinase inhibition in experimental diabetes

Background: It is important to develop orbital hydrogel implants capable of depositing drugs (particularly, antimicrobial and anticancer drugs). Purpose: To assess antimicrobial effects of hybrid hydrogel implants containing gold nanoparticles and albucide and developed for reconstructive surgery in the orbit and periorbital area. Material and Methods: A 30% aqueous solution of albucide was used in the study. Antimicrobial activity of synthesized hydrogels was determined using Escherichia coli ATCC 25922, Enterococcus faecalis ATCC 29213, Staphylococcus aureus ATCC 25923 and Pseudomonasa eruginosa ATCC 27853 strains. Results: All the synthesized samples of orbital hydrogel implants were sterile. The synthesized hydrogels and hydrogel nanocomposites with incorporated Au nanoparticles demonstrated bacteriostatic effects against E. Coli ATCC 25922, E. Faecalis ATCC 29213, and S. Aureus ATCC 25923 strains, and bactericidal effects against P. Aeruginosa ATCC 27853 strain. This study also demonstrated marked bactericidal effects of hybrid hydrogel implants incorporating both Au nanoparticles and albucide. Conclusion: Orbital hydrogel implants were found to be sterile after being sealed into polypropylene bags and steam sterilized at 121 °C for 20 minutes. Our findings of bacteriostatic and bactericidal effects of the synthesized hydrogels and hydrogel nanocomposites containing Au nanoparticles and albucide against bacterial strains of interest will allow for the absence of, or low probability of bacterial contamination in applications of these hydrogels in implants.

Protective effects and mechanisms of Momordica charantia polysaccharide on early-stage diabetic retinopathy in type 1 diabetes

Momordica charantia polysaccharide (MCP) is a potential drug for the prevention and alleviation of diabetes mellitus (DM) and diabetic retinopathy (DR). This study aimed to investigate the potential protective effects of MCP on early-stage DR and explore the underlying mechanisms. The model group (DM group) and treatment group (D+H group) were established by inducing type 1 DM using a single dose of streptozotocin (STZ) at 60 mg/kg. After modeling, the D+H group was orally administered a 500 mg/kg dose of MCP solution once daily for 12 weeks. Monitoring of systemic indicators (FBG, body weight, general condition) and retinal tissue inflammation and apoptosis (HE staining, IL-6, MCP-1, TNF-α, VEGF, NF-κB, Caspase-3) in this study demonstrated that MCP intervention alleviated both DM and DR. MCP improved the body weight and general condition of DM rats by reducing FBG levels. It also enhanced the anti-inflammatory and anti-apoptotic capabilities of retinal neurons and microvessels by modulating the actions of cytokines, thereby further regulating the inflammation and apoptosis of retinal neurons and microvessels. The underlying mechanisms may be associated with the downregulation of NF-κB and Caspase-3 pathway protein expression, as well as the downregulation of mRNA expression of NF-κB and Caspase-3 pathway genes. Further research is needed to elucidate the potential mechanisms underlying the protective effects of MCP on DR. MCP may emerge as a selective medication for the prevention and alleviation of DM and a novel natural medicine for the prevention and alleviation of DR.

COG1410 regulates microglial states and protects retinal ganglion cells in retinal ischemia-reperfusion injury

Progressive loss of retinal ganglion cells (RGCs) caused by retinal ischemia-reperfusion (IR) injury can lead to irreversible vision impairment, with neuroinflammatory responses playing an important role in this process. COG1410, a mimetic peptide of apolipoprotein E, has demonstrated protective potential in the central nervous system, but its effects on retinal IR injury remain unexplored. In this study, we established a mouse model of retinal IR injury to investigate the effects of COG1410 on retinal microglia and RGCs. We observed CD16/32-marked and CD206-marked microglia and RGCs using immunofluorescence staining, detected the expression of inflammatory factors by PCR, and evaluated retinal apoptosis with TUNEL staining. We further investigated the potential mechanism by detecting the expression of key proteins via Western blot. The results reveal that COG1410 decreased the number of CD16/32-marked microglia and increased the number of CD206-marked microglia, alleviated the expression of IL-1β and TNF-α, and reduced the loss of RGCs by inhibiting the mitochondrial-related apoptotic pathway. COG1410 was found to increase the expression of ERK1/2 and Nr4a1 but decrease the expression of NF-κB. The expression of TREM2 showed an increasing trend after COG1410 administration, but it was not statistically significant. In conclusion, COG1410 regulates microglial states and protects RGCs in retinal IR injury, showing promising potential for the treatment of eye diseases.

TGR5 supresses cGAS/STING pathway by inhibiting GRP75-mediated endoplasmic reticulum-mitochondrial coupling in diabetic retinopathy

Diabetic retinopathy (DR) is a serious and relatively under-recognized complication of diabetes. Müller glial cells extend throughout the retina and play vital roles in maintaining retinal homeostasis. Previous studies have demonstrated that TGR5, a member of the bile acid-activated GPCR family, could ameliorate DR. However, the role of TGR5 in regulating Müller cell function and the underlying mechanism remains to be ascertained. To address this, high glucose (HG)-treated human Müller cells and streptozotocin-treated Sprague-Dawley rats were used in the study. The IP3R1-GRP75-VDAC1 axis and mitochondrial function were assessed after TGR5 ablation or agonism. Cytosolic mitochondrial DNA (mtDNA)-mediated cGAS-STING activation was performed. The key markers of retinal vascular leakage, apoptosis, and inflammation were examined. We found that mitochondrial Ca2+ overload and mitochondrial dysfunction were alleviated by TGR5 agonist. Mechanically, TGR5 blocked the IP3R1-GRP75-VDAC1 axis mediated Ca2+ efflux from the endoplasmic reticulum into mitochondria under diabetic condition. Mitochondrial Ca2+ overload led to the opening of the mitochondrial permeability transition pore and the release of mitochondrial DNA (mtDNA) into the cytosol. Cytoplasmic mtDNA bound to cGAS and upregulated 2’3’ cyclic GMP-AMP. Consequently, STING-mediated inflammatory responses were activated. TGR5 agonist prevented retinal injury, whereas knockdown of TGR5 exacerbated retinal damage in DR rats, which was rescued by the STING inhibitor. Based on the above results, we propose that TGR5 might be a novel therapeutic target for the treatment of DR.

Taurine: a promising nutraceutic in the prevention of retinal degeneration.

Taurine is considered a non-essential amino acid because it is synthesized by most mammals. However, dietary intake of taurine may be necessary to achieve the physiological levels required for the development, maintenance, and function of certain tissues. Taurine may be especially important for the retina. The concentration of taurine in the retina is higher than that in any other tissue in the body and taurine deficiency causes retinal oxidative stress, apoptosis, and degeneration of photoreceptors and retinal ganglion cells. Low plasma taurine levels may also underlie retinal degeneration in humans and therefore, taurine administration could exert retinal neuroprotective effects. Taurine has antioxidant, anti-apoptotic, immunomodulatory, and calcium homeostasis-regulatory properties. This review summarizes the role of taurine in retinal health and disease, where it appears that taurine may be a promising nutraceutical.

CREG Protects Retinal Ganglion Cells loss and Retinal Function Impairment Against ischemia-reperfusion Injury in mice via Akt Signaling Pathway.

The irreversible death of retinal ganglion cells (RGCs) plays an important role in the pathogenesis of glaucoma. Cellular repressor of E1A-stimulated genes (CREG), a secreted glycoprotein involved in cellular proliferation and differentiation, has been shown to protect against myocardial and renal ischemia-reperfusion damage. However, the role of CREG in retinal ischemia-reperfusion injury (RIRI) remains unknown. In this study, we aimed to explore the effect of CREG on RGCs apoptosis after RIRI. We used male C57BL/6J mice to establish the RIRI model. Recombinant CREG was injected at 1day before RIRI. The expression and distribution of CREG were examined by immunofluorescence staining and western blotting. RGCs survival was assessed by immunofluorescence staining of flat-mounted retinas. Retinal apoptosis was measured by the staining of TdT-mediated dUTP nick-end labeling and cleaved caspase-3. Electroretinogram (ERG)analysis and optomotor response were conducted to evaluate retinal function and visual acuity. The expressions of Akt, phospho-Akt (p-Akt), Bax, and Bcl-2 were analyzed by western blotting to determine the signaling pathways of CREG. We found that CREG expression was decreased after RIRI, and intravitreal injection of CREG attenuated RGCs loss and retinal apoptosis. Besides, the amplitudes of a-wave, b-wave, and photopic negative response (PhNR) in ERG, as well as visual function, were significantly restored after treatment with CERG. Furthermore, intravitreal injection of CREG upregulated p-Akt and Bcl-2 expression and downregulated Bax expression. Our results demonstrated that CREG protected RGCs from RIRI and alleviated retinal apoptosis by activating Akt signaling. In addition, CREG also improved retinal function and visual acuity.

Inhibition of NOX4 with GLX351322 alleviates acute ocular hypertension-induced retinal inflammation and injury by suppressing ROS mediated redox-sensitive factors activation

Reactive oxygen species (ROS) overproduction plays an essential role in the etiology of ischemic/hypoxic retinopathy caused by acute glaucoma. NADPH oxidase (NOX) 4 was discovered as one of the main sources of ROS in glaucoma. However, the role and potential mechanisms of NOX4 in acute glaucoma have not been fully elucidated. Therefore, the current study aims to investigate the NOX4 inhibitor GLX351322 that targets NOX4 inhibition in acute ocular hypertension (AOH)-induced retinal ischemia/hypoxia injury in mice. Herein, NOX4 was highly expressed in AOH retinas, particularly the retinal ganglion cell layer (GCL). Importantly, the NOX4 inhibitor GLX351322 reduced ROS overproduction, inhibited inflammatory factor release, suppressed glial cell activation and hyperplasia, inhibited leukocyte infiltration, reduced retinal cell senescence and apoptosis in damaged areas, reduced retinal degeneration and improved retinal function. This neuroprotective effect is at least partially associated with mediated redox-sensitive factor (HIF-1α, NF-κB, and MAPKs) pathways by NOX4-derived ROS overproduction. These results suggest that inhibition of NOX4 with GLX351322 attenuated AOH-induced retinal inflammation, cellular senescence, and apoptosis by inhibiting the activation of the redox-sensitive factor pathway mediated by ROS overproduction, thereby protecting retinal structure and function. Targeted inhibition of NOX4 is expected to be a new idea in the treatment of acute glaucoma.

MiR-93-5p inhibits retinal neurons apoptosis by regulating PDCD4 in acute ocular hypertension model.

The present study focused on the effect of miR-93-5p on apoptosis of retinal neurons in acute ocular hypertension (AOH) model by regulating PDCD4 and explored its related mechanism. We detected that miR-93-5p expression was decreased and PDCD4 expression was increased in the AOH retina by qRT-PCR. Therefore, we explored the role of miR-93-5p and PDCD4. MiR-93-5p overexpression inhibited the apoptosis of retinal neurons and the expression of PDCD4 in vivo and in vitro. Inhibiting the expression of PDCD4 via transfected interfering RNA decreased the apoptosis of retinal cells and increased the expression of PI3K/Akt pathway-related proteins in vitro. However, the addition of PI3K protein inhibitor LY294002 reversed this effect, leading to a decrease of PI3K/Akt pathway protein expression and an increase of apoptosis-related protein Bax/Bcl-2 expression ratio. Finally, up-regulating miR-93-5p or down-regulating PDCD4 increased the expression of PI3K/Akt pathway protein in vivo. In conclusion, under the condition of AOH injury, miR-93-5p-inhibiting PDCD4 expression reduced the apoptosis of retinal neurons by activating PI3K/Akt pathway.

Effects of fresh bone marrow mononuclear cell therapy in rat model of retinopathy of prematurity

IntroductionRetinopathy of prematurity (ROP) is a vasoproliferative disease that alters retinal vascular patterns in preterm neonates with immature retinal vasculature. This study was conducted to investigate the effects of cell therapy by bone marrow mononuclear cells (BMMNC) on neurological and vascular damages in a rat model of ROP. MethodsTen newborn Wistar rats were divided randomly into the control and the oxygen-induced retinopathy (OIR) groups. Animals in the OIR group were incubated in an oxygen chamber to induce retinopathy. One eye of animals in the OIR group received BMMNC suspension (treated eyes), and the contralateral eye received the same volume of saline injection. Then, all animals underwent funduscopy, angiography, electroretinography, histopathology and immunohistochemical assessments. ResultsCompared to the saline injection group, eyes treated with BMMNC had less vascular tortuosity while veins and arteries had relatively the same caliber, as revealed by fundus examinations. Eyes in the treatment group showed significantly elevated photopic and scotopic B waves amplitude. Neovascularization in the inner retinal layer and apoptosis of neural retina cells in the treatment group was significantly lower compared to untreated eyes. Also, BMMNC transplantation decreased glial cell activation and VEGF expression in ischemic retina. ConclusionsOur results indicate that intravitreal injection of BMMNC reduces neural and vascular damages and results in recovered retinal function in rat model of ROP. Ease of extraction without in vitro processing, besides the therapeutic effects of BMMNCs, make this source of cells as a new choice of therapy for ROP or other retinal ischemic diseases.

Curcumin attenuates hydroxychloroquine-mediated apoptosis and oxidative stress via the inhibition of TRPM2 channel signalling pathways in a retinal pigment epithelium cell line.

Hydroxychloroquine (HCQ) is used in the treatment of several diseases, such as malaria, Sjögren's disease, Covid-19, and rheumatoid arthritis. However, HCQ induces retinal pigment epithelium death via the excessive increase of cytosolic (cROS) and mitochondrial (mROS) free oxygen radical production. The transient receptor potential melastatin 2 (TRPM2) cation channel is stimulated by ADP-ribose (ADPR), cROS, and mROS, although it is inhibited by curcumin (CRC). We aimed to investigate the modulating action of CRC on HCQ-induced TRPM2 stimulation, cROS, mROS, apoptosis, and death in an adult retinal pigment epithelial 19 (ARPE19) cell line model. ARPE19 cells were divided into four groups: control (CNT), CRC (5µM for 24h), HCQ (60µM for 48h), and CRC + HCQ groups. The levels of cell death (propidium iodide positive cell numbers), apoptosis markers (caspases -3, -8, and -9), oxidative stress (cROS and mROS), mitochondria membrane depolarization, TRPM2 current density, and intracellular free Ca2+ and Zn2+ fluorescence intensity were upregulated in the HCQ group after stimulation with hydrogen peroxide and ADPR, but their levels were downregulated by treatments with CRC and TRPM2 blockers (ACA and carvacrol). The HCQ-induced decrease in retinal live cell count and cell viability was counteracted by treatment with CRC. HCQ-mediated overload Ca2+ influx and retinal oxidative toxicity were induced in an ARPE19 cell line through the stimulation of TRPM2, although they were attenuated by treatment with CRC. Hence, CRC may be a potential therapeutic antioxidant for TRPM2 activation and HCQ treatment-induced retinal oxidative injury and apoptosis.

Translocator protein 18 kDa regulates retinal neuron apoptosis and pyroptosis in glaucoma

Glaucoma is the leading cause of blindness worldwide. However, our insufficient understanding of the pathogenesis of glaucoma has limited the development of effective treatments. Because recent research has highlighted the importance of non-coding RNAs (ncRNAs) in various diseases, we investigated their roles in glaucoma. Specifically, we detected expression changes of ncRNAs in cell and animal models of acute glaucoma. Further analysis revealed that the Ier2/miR-1839/TSPO axis was critical to cell loss and retinal damage. The knockdown of Ier2, the overexpression of miR-1839, and the silencing of TSPO effectively prevented retinal damage and cell loss. Furthermore, we found that the Ier2/miR-1839/TSPO axis regulated the pyroptosis and apoptosis of retinal neurons through the NLRP3/caspase1/GSDMD, cleaved-caspase3 pathways. In addition to high expression in the retina, TSPO expression was found to be significantly higher in the dorsal lateral geniculate nucleus (DLG) of the brain in the pathologically high intraocular pressure (ph-IOP) rat model, as well as in the peripheral blood mononuclear cells (PBMCs) of glaucoma patients with high IOP. These results indicate that TSPO, which is regulated by Ier2/miR-1839, plays an important role in the pathogenesis of glaucoma, and this study provides a theoretical basis and a new target for the diagnosis and treatment of glaucoma.

EIF2α incites photoreceptor cell and retina damage by all-trans-retinal

Dry age-related macular degeneration (AMD) and recessive Stargardt's disease (STGD1) lead to irreversible blindness in humans. The accumulation of all-trans-retinal (atRAL) induced by chaos in visual cycle is closely associated with retinal atrophy in dry AMD and STGD1 but its critical downstream signaling molecules remain ambiguous. Here, we reported that activation of eukaryotic translation initiation factor 2α (eIF2α) by atRAL promoted retinal degeneration and photoreceptor loss through activating c-Jun N-terminal kinase (JNK) signaling-dependent apoptosis and gasdermin E (GSDME)-mediated pyroptosis. We determined that eIF2α activation by atRAL in photoreceptor cells resulted from endoplasmic reticulum homeostasis disruption caused at least in part by reactive oxygen species production, and it activated JNK signaling independent of and dependent on activating transcription factor 4 and the activating transcription factor 4/transcription factor C/EBP homologous protein (CHOP) axis. CHOP overexpression induced apoptosis of atRAL-loaded photoreceptor cells through activating JNK signaling rather than inhibiting the expression of antiapoptotic gene Bcl2. JNK activation by eIF2α facilitated photoreceptor cell apoptosis caused by atRAL via caspase-3 activation and DNA damage. Additionally, we demonstrated that eIF2α was activated in neural retina of light-exposed Abca4-/-Rdh8-/- mice, a model that shows severe defects in atRAL clearance and displays primary features of human dry AMD and STGD1. Of note, inhibition of eIF2α activation by salubrinal effectively ameliorated retinal degeneration and photoreceptor apoptosis in Abca4-/-Rdh8-/- mice upon light exposure. The results of this study suggest that eIF2α is an important target to develop drug therapies for the treatment of dry AMD and STGD1.

Long-term blue light exposure impairs mitochondrial dynamics in the retina in light-induced retinal degeneration in vivo and in vitro.

Long-term light exposure, especially in the spectrum of blue light, frequently causes excessive oxidative stress in dry age-related macular degeneration (AMD). Here, to gain insight into the underlying mechanism, we focused on mitochondrial dynamics alterations under long-term exposure to blue light in mouse and retinal cells. Six-month-old C57BL/6 mice were exposed to blue light (450nm, 800lx) for 2weeks. The phenotypic changes in the retina were assayed using haematoxylin-eosin staining and transmission electron microscopy. Long-term blue light exposure significantly thinned each retinal layer in mice, induced retinal apoptosis and impaired retinal mitochondria. A retinal pigment epithelial cell line (ARPE-19) was used to verify the phototoxicity of blue light. Flow cytometry, immunofluorescence and MitoSox Red probe experiments confirmed that more total and mitochondria-specific ROS were generated in the blue light group than in the control group. Mito-Tracker Green probe showed fragmented mitochondrial morphology. The western blotting results indicated a significant increase in DRP1, OMA1, and BAX and a decrease in OPA1 and Bcl-2. In conclusion, long-term exposure to blue light damaged the retinas of mice, especially the ONL and RPE cells. There was destruction and dysfunction of mitochondria in RPE cells in vivo and in vitro. Mitochondrial dynamics were disrupted with characteristics of fusion-related obstruction after blue-light irradiation.

Stem cells and diabetic retinopathy: From models to treatment.

Diabetic retinopathy is a common yet complex microvascular disease, caused as a complication of diabetes mellitus. Associated with hyperglycemia and subsequent metabolic abnormalities, advanced stages of the disease lead to fibrosis, subsequent visual impairment and blindness. Though clinical postmortems, animal and cell models provide information about the progression and prognosis of diabetic retinopathy, its underlying pathophysiology still needs a better understanding. In addition to it, the loss of pericytes, immature retinal angiogenesis and neuronal apoptosis portray the disease treatment to be challenging. Indulged with cell loss of both vascular and neuronal type cells, novel therapies like cell replacement strategies by various types of stem cells have been sightseen as a possible treatment of the disease. This review provides insight into the pathophysiology of diabetic retinopathy, current models used in modelling the disease, as well as the varied aspects of stem cells in generating three-dimensional retinal models. Further outlook on stem cell therapy and the future directions of stem cell treatment in diabetic retinopathy have also been contemplated.

Effects of acute exposure to amisulbrom on retinal development in zebrafish (Danio rerio) embryos.

Amisulbrom is an oomycete-specific fungicide that was developed by Nissan Chemical Industries Limited. The exposure of developing zebrafish embryo to amisulbrom caused disorders in the visual phototransduction system. However, the potential toxic mechanisms of amisulbrom on retinal development remains unclear. The research purpose of this study was to evaluate the adverse effects of amisulbrom on retinal development in a model organism, the zebrafish. Zebrafish embryos were treated with 0, 0.0075, 0.075, or 0.75μM amisulbrom from 3h post-fertilization (hpf) to 72 hpf. Compared with the control group, amisulbrom-treated zebrafish embryos displayed phenotypic microphthalmia, dysregulation of gene transcription levels (alcama, prox1a, sox2, vsx1, rho, bluops, rdops, uvops, and grops) related to the retinal cell layer differentiation, and increased retinal apoptosis. In addition, the content of glutathione and malondialdehyde increased significantly after exposure to amisulbrom. Overall, our data demonstrate the toxicity of amisulbrom to eye development, which will help to assess the potential ecotoxicological impacts posed by amisulbrom to aquatic species.

Lactate protects against oxidative stress-induced retinal degeneration by activating autophagy.

Age-related macular degeneration is a common cause of blindless among the aged, which can mainly be attributed to oxidative stress and dysregulated autophagy in retinal pigment epithelium cells. Lactate was reported to act as a signaling molecule and exerted beneficial effect against oxidative stress. This study aims to investigate the protective effect of lactate against oxidative stress-induced retinal degeneration. Here, H2O2-induced oxidative stress cell model and sodium iodate-induced mice retinal degeneration model were established. It was found that H2O2 inhibited cell viability in ARPE-19cells and sodium iodate induced deterioration of retinal pigment epithelium as well as apoptosis in retina. Pretreatment with lactate alleviated oxidative stress-induced cell death and retinal degeneration. Molecularly, lactate activated autophagy by up-regulating the ratio of LC3II/I, increased formation of LC3 puncta and autophagic vacuole. Further, lactate prevented H2O2-induced mitochondrial fission and maintained mitochondrial function by alleviating H2O2-induced mitochondrial membrane potential disruption and intracellular ROS generation. In contrast, application of 3-methyladenine, an inhibitor of autophagy, effectively weakened the protective effect of lactate against oxidative stress in vivo and in vitro. Taken together, all data in this study indicate that lactate protects against oxidative stress-induced retinal degeneration and preserves mitochondrial function by activating autophagy.

The protective effects of beta-mangostin against sodium iodate-induced retinal ROS-mediated apoptosis through MEK/ERK and p53 signaling pathways.

Previous studies have indicated that NaIO3 induces intracellular reactive oxygen species (ROS) production and has been used as a model for age-related macular degeneration (AMD) due to the selective retinal pigment epithelium (RPE) cell damage it induces. Beta-mangostin (BM) is a xanthone-type natural compound isolated from Cratoxylum arborescens. The influence of BM on NaIO3-induced oxidative stress damage in ARPE-19 cells has not yet been elucidated. In this study, we investigated how BM protects ARPE-19 cells from NaIO3-induced ROS-mediated apoptosis. Our results revealed that BM notably improved cell viability and prevented ARPE-19 cell mitochondrial dysfunction mediated-apoptosis induced by NaIO3; it was mediated by significantly reduced NaIO3-upregulated ROS, cellular H2O2 production and improved downregulated glutathione and catalase activities. Furthermore, we found that BM could suppress the expression of Bax, cleaved PARP, and cleaved caspase-3 by decreasing phosphorylation of MEK/ERK and p53 expression in NaIO3-induced ARPE-19 cells. At the same time, we also used MEK inhibitors (PD98059) to confirm the above phenomenon. Moreover, our animal experiments revealed that BM prevented NaIO3 from causing retinal deformation; it led to thicker outer and inner nuclear layers and downregulated cleaved caspase-3 expression compared to the group receiving NaIO3 only. Collectively, these results suggest that BM can protect the RPE and retina from NaIO3-induced apoptosis through ROS-mediated mitochondrial dysfunction involving the MEK/ERK and p53 signaling pathways.

In Vivo Detection of Retinal Ganglion Cell Stress in Rodents with DARC.

DARC (detection of apoptosing retinal cells) uses fluorescently tagged Annexin A5 to identify retinal apoptosis non-invasively in vivo using a confocal laser scanning ophthalmoscope (cSLO). This can provide insights into the presence and progression of disease pathology and the efficacy of neuroprotective intervention. The methods of administration, imaging, and quantification of DARC, including the operation of the cSLO, are described here.