Pathology Of Diabetic Retinopathy Research Articles

Heme: A link between hemorrhage and retinopathy of prematurity progression

Neovascularization is implicated in the pathology of retinopathy of prematurity (ROP), diabetic retinopathy (DR), and age-related macular degeneration (AMD), which are the leading causes of blindness worldwide. In our work, we analyzed how heme released during hemorrhage affects hypoxic response and neovascularization. Our retrospective clinical analysis demonstrated, that hemorrhage was associated with more severe retinal neovascularization in ROP patients. Our heme-stimulated human retinal pigment epithelial (ARPE-19) cell studies demonstrated increased expression of positive regulators of angiogenesis, including vascular endothelial growth factor-A (VEGFA), a key player of ROP, DR and AMD, and highlighted the activation of the PI3K/AKT/mTOR/VEGFA pathway involved in angiogenesis in response to heme. Furthermore, heme decreased oxidative phosphorylation in the mitochondria, augmented glycolysis, facilitated HIF-1α nuclear translocation, and increased VEGFA/GLUT1/PDK1 expression suggesting HIF-1α-driven hypoxic response in ARPE-19 cells without effecting the metabolism of reactive oxygen species. Inhibitors of HIF-1α, PI3K and suppression of mTOR pathway by clinically promising drug, rapamycin, mitigated heme-provoked cellular response. Our data proved that oxidatively modified forms of hemoglobin can be sources of heme to induce VEGFA during retinal hemorrhage. We propose that hemorrhage is involved in the pathology of ROP, DR, and AMD.

Prospects and limitations of cumate-inducible lentivirus as a tool for investigating VEGF-A-mediated pathology in diabetic retinopathy

Diabetic retinopathy (DR) is a multifactorial disease displaying vascular-associated pathologies, including vascular leakage and neovascularization, ultimately leading to visual impairment. However, animal models accurately reflecting these pathologies are lacking. Vascular endothelial growth factor A (VEGF-A) is an important factor in the development of micro- and macro-vascular pathology in DR. In this study, we evaluated the feasibility of using a cumate-inducible lentivirus (LV) mediated expression of vegf-a to understand DR pathology in vitro and in vivo. Retinal pigment epithelial cells (ARPE-19) were transduced with cumate-inducible LV expressing vegf-a, with subsequent analysis of vegf-a expression and its impact on cell proliferation, viability, motility, and permeability. Cumate tolerability in adult Wistar rat eyes was assessed as an initial step towards a potential DR animal model development, by administering cumate via intravitreal injections (IVT) and evaluating consequent effects by spectral domain optical coherence tomography (SD-OCT), flash electroretinography (fERG), ophthalmic examination (OE), and immunohistochemistry. Transduction of ARPE-19 cells with cumate-inducible LV resulted in ~ 2.5-fold increase in vegf-a mRNA and ~ threefold increase in VEGF-A protein secretion. Transduced cells displayed enhanced cell proliferation, viability, permeability, and migration in tube-like structures. However, IVT cumate injections led to apparent retinal toxicity, manifesting as retinal layer abnormalities, haemorrhage, vitreous opacities, and significant reductions in a- and b-wave amplitudes, along with increased microglial activation and reactive gliosis. In summary, while cumate-inducible LV-mediated vegf-a expression is valuable for in vitro mechanistic studies in cellular drug discovery, its use is not a feasible approach to model DR in in vivo studies due to cumate-induced retinal toxicity.

Astrogliosis in the GFAP-CreERT2:Rosa26iDTR Mouse Model Does Not Exacerbate Retinal Microglia Activation or Müller Cell Gliosis under Hypoxic Conditions.

Diabetic retinopathy (DR) affects over 140 million people globally. The mechanisms that lead to blindness are still enigmatic but there is evidence that sustained inflammation and hypoxia contribute to vascular damage. Despite efforts to understand the role of inflammation and microglia in DR's pathology, the contribution of astrocytes to hypoxic responses is less clear. To investigate the role of astrocytes in hypoxia-induced retinopathy, we utilized a 7-day systemic hypoxia model using the GFAP-CreERT2:Rosa26iDTR transgenic mouse line. This allows for the induction of inflammatory reactive astrogliosis following tamoxifen and diphtheria toxin administration. We hypothesize that DTx-induced astrogliosis is neuroprotective during hypoxia-induced retinopathy. Glial, neuronal, and vascular responses were quantified using immunostaining, with antibodies against GFAP, vimentin, IBA-1, NeuN, fibrinogen, and CD31. Cytokine responses were measured in both the brain and serum. We report that while both DTx and hypoxia induced a phenotype of reduced microglia morphological activation, DTx, but not hypoxia, induced an increase in the Müller glia marker vimentin. We did not observe that the combination of DTx and hypoxic treatments exacerbated the signs of reactive glial cells, nor did we observe a significant change in the expression immunomodulatory mediators IL-1β, IL2, IL-4, IL-5, IL-6, IL-10, IL-18, CCL17, TGF-β1, GM-CSF, TNF-α, and IFN-γ. Overall, our results suggest that, in this hypoxia model, reactive astrogliosis does not alter the inflammatory responses or cause vascular damage in the retina.

Computational and Experimental Approaches Exploring the Role of Hesperetin in Improving Autophagy in Rat Diabetic Retinopathy.

Diabetic retinopathy (DR) is a debilitating diabetic disorder of the retinal microvasculature and the main cause of avoidable blindness in old people. Hesperetin is a plant flavanone largely abundant in citrus species with neuroprotective properties in animal models. This study aimed to explore the neuroprotective and autophagy-enhancing effect of hesperetin in rats with DR. Twenty-four male rats were utilized and allocated to groups: (i) the vehicle group, (ii) DR group and (iii-iv) the DR + hesperetin (50 and 100 mg/kg) groups. Treatment with hesperetin continued for 6 weeks. After the rats were euthanized, their eyes were dissected to detect the biochemical and histological changes in the retinas. Quantification of autophagy markers, beclin 1/LC3/p62, and inflammation markers was performed. Histopathologic changes were investigated after staining with hematoxylin and eosin and periodic acid-Schiff (PAS). Results demonstrated that hesperetin decreased the PAS staining in diabetic rats and attenuated histopathological changes and restored retinal organization and thickness of layers in hematoxylin and eosin staining. Moreover, hesperetin reduced the level of mRNA expression for TNF-α (4.9-fold), IL-1β (4.15-fold), IL-6 (4.6-fold) and NFκB (5.2-fold), as well as the protein level. This was accompanied by induction of autophagy proteins, beclin 1 and LC3-II. Our results afford evidence that hesperetin is effective in alleviating the pathology of DR via suppressing the inflammatory burden and induction of autophagy. After extensive clinical examinations, hesperetin may prove to be a useful option for treatment of DR.

TNFSF15 inhibits progression of diabetic retinopathy by blocking pyroptosis via interacting with GSDME

Diabetic retinopathy is a common microvascular complication of diabetes and a leading cause of blindness. Pyroptosis has emerged as a mechanism of cell death involved in diabetic retinopathy pathology. This study explored the role of GSDME-mediated pyroptosis and its regulation by TNFSF15 in diabetic retinopathy. We found GSDME was upregulated in the progression of diabetic retinopathy. High glucose promoted GSDME-induced pyroptosis in retinal endothelial cells and retinal pigment epithelial cells, attributed to the activation of caspase-3 which cleaves GSDME to generate the pyroptosis-executing N-terminal fragment. TNFSF15 was identified as a binding partner and inhibitor of GSDME-mediated pyroptosis. TNFSF15 expression was increased by high glucose but suppressed by the caspase-3 activator Raptinal. Moreover, TNFSF15 protein inhibited high glucose- and Raptinal-induced pyroptosis by interacting with GSDME in retinal cells. Collectively, our results demonstrate TNFSF15 inhibits diabetic retinopathy progression by blocking GSDME-dependent pyroptosis of retinal cells, suggesting the TNFSF15-GSDME interaction as a promising therapeutic target for diabetic retinopathy.

HAGLR, stabilized by m6A modification, triggers PTEN-Akt signaling cascade-mediated RPE cell pyroptosis via sponging miR-106b-5p.

Consistent hyperglycaemia on retinal microvascular tissues is recognized as a vital inducer of diabetic retinopathy (DR) pathogenesis. In view of the essential functionality of long noncoding RNAs (lncRNAs) in multiple human diseases, we aim to figure out the exact role and underlying mechanisms of lncRNA HOXD Cluster Antisense RNA 1 (HAGLR) in DR pathogenesis. Serum specimens from patients with proliferative DR and healthy volunteers were collected for measuring HAGLR levels. Human primary retinal pigment epithelium (HRPE) cells kept in high glucose (HG) condition were applied to simulating hyperglycaemia of DR pathology in vitro. Cell proliferation, apoptosis, either pyroptosis was assess using Cell Counting Kit-8 TUNEL, flow cytometry, and enzyme-linked immunoassay assays. Bioinformatics analysis was subjected to examine the interaction between HAGLR and N6-methyladenosine (m6A)-bind protein IGF2BP2, as determined using RNA immunoprecipitation and RNA pull-down. Luciferase reporter assay was performed to assess the HAGLR-miR-106b-5p-PTEN axis. Levels of pyroptosis-associated biomarkers were detected using western blotting. Aberrantly overexpressed HAGLR was uncovered in the serum samples of DR patients and HG-induced HRPE cells, of which knockdown attenuated HG-induced cytotoxic impacts on cell apoptosis and pyroptosis. Whereas, reinforced HAGLR further aggravated these effects. IGF2BP2 positively regulated HAGLR in a m6A-dependent manner. HAGLR served as a sponge for miR-106b-5p to upregulate PTEN, thereby activating Akt signaling cascade. Rescue assays demonstrated that PTEN overexpression abolished the inhibition of silenced HAGLR on pyroptosis in HRPE cells. HAGLR, epigenetically modified by IGF2BP2 in an m6A-dependent manner, functioned as a sponge for miR-106b-5p, thereby activating PTEN/Akt signaling cascade to accelerate DR pathology.

Diabetic Müller-Glial-Cell-Specific Il6ra Knockout Mice Exhibit Accelerated Retinal Functional Decline and Thinning of the Inner Nuclear Layer.

Interleukin-6 (IL-6) is implicated in the pathology of diabetic retinopathy (DR). IL-6 trans-signaling via soluble IL-6 receptor (IL-6R) is primarily responsible for its pro-inflammatory functions, whereas cis-signaling via membrane-bound IL-6R is anti-inflammatory. Using a Müller-glial-cell-specific Il6ra-/- mouse, we examined how loss of IL-6 cis-signaling in Müller glial cells (MGCs) affected retinal thinning and electroretinography (ERG) response over 9months of diabetes. Diabetes was induced in wildtype and knockout mice with streptozotocin (40mg/kg, daily for 5days). Spectral domain optical coherence tomography (SD-OCT), ERG, and fundoscopy/fluorescein angiography (FA) were assessed at 2, 6, and 9months of diabetes. MGCs and bipolar neurons were examined in retinal tissue sections by immunofluorescence. Diabetic MGC Il6ra-/- mice had significantly thinner retinas than diabetic wildtype mice at 2 (-7.6µm), 6 (-12.0µm), and 9months (-5.0µm) of diabetes, as well as significant thinning of the inner nuclear layer (INL). Diabetic MGC Il6ra-/- mice also showed a reduction in scotopic B-wave amplitude and B-wave/A-wave ratio earlier than wildtype diabetic mice. In retinal sections, we found a decrease in bipolar neuronal marker PKCα only in diabetic MGC Il6ra-/- mice, which was significantly lower than both controls and diabetic wildtype mice. Glutamine synthetase, a Müller cell marker, was reduced in both wildtype and MGC Il6ra-/- diabetic mice compared to their respective controls. IL-6 cis-signaling in MGCs contributes to maintenance of the INL in diabetes, and loss of the IL-6 receptor reduces MGC-mediated neuroprotection of bipolar neurons in the diabetic retina.

Competing risks analysis for neutrophil to lymphocyte ratio as a predictor of diabetic retinopathy incidence in the Scottish population

BackgroundDiabetic retinopathy (DR) is a major sight-threatening microvascular complication in individuals with diabetes. Systemic inflammation combined with oxidative stress is thought to capture most of the complexities involved in the pathology of diabetic retinopathy. A high level of neutrophil–lymphocyte ratio (NLR) is an indicator of abnormal immune system activity. Current estimates of the association of NLR with diabetes and its complications are almost entirely derived from cross-sectional studies, suggesting that the nature of the reported association may be more diagnostic than prognostic. Therefore, in the present study, we examined the utility of NLR as a biomarker to predict the incidence of DR in the Scottish population.MethodsThe incidence of DR was defined as the time to the first diagnosis of R1 or above grade in the Scottish retinopathy grading scheme from type 2 diabetes diagnosis. The effect of NLR and its interactions were explored using a competing risks survival model adjusting for other risk factors and accounting for deaths. The Fine and Gray subdistribution hazard model (FGR) was used to predict the effect of NLR on the incidence of DR.ResultsWe analysed data from 23,531 individuals with complete covariate information. At 10 years, 8416 (35.8%) had developed DR and 2989 (12.7%) were lost to competing events (death) without developing DR and 12,126 individuals did not have DR. The median (interquartile range) level of NLR was 2.04 (1.5 to 2.7). The optimal NLR cut-off value to predict retinopathy incidence was 3.04. After accounting for competing risks at 10 years, the cumulative incidence of DR and deaths without DR were 50.7% and 21.9%, respectively. NLR was associated with incident DR in both Cause-specific hazard (CSH = 1.63; 95% CI: 1.28–2.07) and FGR models the subdistribution hazard (sHR = 2.24; 95% CI: 1.70–2.94). Both age and HbA1c were found to modulate the association between NLR and the risk of DR.ConclusionsThe current study suggests that NLR has a promising potential to predict DR incidence in the Scottish population, especially in individuals less than 65 years and in those with well-controlled glycaemic status.

Implications of Caspase 1/ Interleukin-1 Beta (IL-1β) Signaling and Hypoxia-Inducible Factor 1-Alpha (HIF-1α) on Diabetic Retinopathy Pathology.

Diabetic retinopathy (DR) is the leading cause of adult blindness and partial vision loss in modern society for hyperglycemic patients. Accordingly, new treatment options are imperative to the overall reduction of DR prevalence and the ongoing progression of already affected candidates. There are many diseases that are the direct result of specific inflammatory processes. In this literature, DR is looked at as a potential disease that can be alleviated by targeting caspase 1/ interleukin-1 beta (IL-1β), and hypoxia-inducible factor 1-alpha (HIF-1α) signaling pathways and reducing cytokine mobilization within retinal tissues. Caspase-1 is thought to be upregulated during retinal capillary degeneration and other ocular complications. Hypoxia-inducible factor 1-alpha(HIF-1α) is implicated in its role in neovascularization and cell apoptosis within a retinal cell line. Both of these proteins are shown to be significantly elevated in hyperglycemic and galactosemic mice and, when knocked out, seem to have the reverse effect, showing that there is room for potential non-invasive therapy involving these proteins in the future. Vascular endothelial growth factor-alpha (VEGF-A) is also examined as a main signaling protein involved in the manifestation of DR.

Research progress on the mechanism of ferroptosis and its role in diabetic retinopathy.

Ferroptosis is iron-dependent regulatory cell death (RCD). Morphologically, ferroptosis is manifested as mitochondrial atrophy and increased mitochondrial membrane density. Biochemically, ferroptosis is characterized by the depletion of glutathione (GSH), the inactivation of glutathione peroxidase 4 (GPX4), and an increase in lipid peroxides (LPO)and divalent iron ions. Ferroptosis is associated with various diseases, but the relationship with diabetic retinopathy(DR) is less studied. DR is one of the complications of diabetes mellitus and has a severe impact on visual function. The pathology of DR is complex, and the current treatment is unsatisfactory. Therefore, exploring pathogenesis is helpful for the clinical treatment of DR. This paper reviews the pathological mechanism of ferroptosis and DR in recent years and the involvement of ferroptosis in the pathology of DR. In addition, we propose problems that need to be addressed in this research field. It is expected to provide new ideas for treating DR by analyzing the role of ferroptosis in DR.

The role of lutein-rich purple sweet potato leaf extract on the amelioration of diabetic retinopathy in streptozotocin-induced Sprague-Dawley rats.

The objective of this study is to access the effect of purple sweet potato leaf (PSPL) extract on diabetic retinopathy (DR) of streptozotocin (STZ)-induced male Sprague-Dawley (SD) rats. In this study, rats were injected intraperitoneally with a single dose of 60mg/kg STZ, and diabetes was confirmed on day 7. Rats were further divided into a few groups, which were then orally administered with one of the following treatments: 25mg/kg of gliclazide (D25G), 200mg/kg of PSPL extract (DT 200), and 400mg/kg of PSPL extract (DT 400). However, the normal control (NS) and control group for diabetic (DNS) were given normal saline (NS) for 12weeks. The results show that the treated group demonstrated a reduction in serum oral glucose tolerance test (OGTT) levels of DT 200 and DT 400, and an increase in the serum and retinal insulin levels, and restored oxidative stress markers in serum and retina on week 12. The PSPL extract exhibited protective effects in maintaining the kidney, liver, retina, and pancreas architecture in 400mg/kg compared to the 200mg/kg treated group and D25G, thereby restoring fully transparent lenses in diabetes-induced rats. In conclusion, 400mg/kg PSPL is the most effective dose for the amelioration of STZ-induced DR pathology in male SD rats.

Diabetes, Diabetic Retinopathy, and Inflammatory Disorders

ABSTRACT This review summarizes the impact of systemic and ocular inflammatory disorders on diabetes mellitus (DM) and diabetic retinopathy (DR). Local inflammation is a key pathology in diabetic retinopathy (DR) and is also an evolving target for clinical therapy. The legacy effects of local inflammation at the intracellular level make DR a persistent self-driven vicious process. Ocular inflammation is accompanied as well as incited by systemic inflammation due to diabetes mellitus (DM) itself. Over the years, a multitude of studies have evaluated the impact of systemic inflammatory disorders (SIDs, like rheumatoid arthritis, lupus, psoriasis, etc.) and anti-inflammatory drugs prescribed for managing them on manifestations of DM. Recent studies have indicated increased insulin resistance to be a result of chronic inflammation, and the anti-inflammatory drugs to have a protective effect towards DM. Very few studies have evaluated the impact of SIDs on DR. Furthermore, the evidence from these studies is conflicting, and while local anti-inflammatory therapy has shown a lot of clinical potential for use in DR, the results of systemic anti-inflammatory therapies have been inconsistent. The impact of local ocular inflammation due to uveitis on DR is a crucial aspect that has not been evaluated well at present. Initial pre-clinical studies and small-sized clinical reports have shown a strong and positive relationship between the presence of uveitis and the severity of DR as well as its progression, while larger cross-sectional patient surveys have refuted the same. The long term impact of ocular inflammation due to uveitis on DR needs to be studied while adjusting for confounders.

Diosgenin, a Natural Steroidal Sapogenin, Alleviates the Progression of Diabetic Retinopathy in Diabetic Mice.

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and a major cause of blindness in working-age adults. Diosgenin (DG), a natural steroidal sapogenin extracted from fenugreek seeds and wild yam roots, has hypolipidemic, hypoglycemic, anticancer, and anti-inflammatory properties. Given its pharmacological effects, we speculated that DG may be a promising treatment for DR. Therefore, this study was aimed at evaluating the effectiveness of DG in preventing or slowing DR progression in a mouse model (+Leprdb/+Leprdb strain) of type 2 diabetes (T2D). DG (5.0 mg/kg body weight) or phosphate-buffered saline (PBS) was administered to 8-week-old T2D mice via oral gavage daily for 24 weeks. Paraffin-embedded eye tissues from the mice were collected and stained with hematoxylin and eosin to evaluate retinal histopathology. Apoptosis-related proteins BCL2-associated X (Bax), B-cell lymphoma 2 (Bcl-2), and cleaved caspase-3 were evaluated by western blotting of mouse retinas. Body weight was slightly reduced in the DG-treated group; however, glucose levels were not markedly different between the DG- and PBS-treated groups. Total retinal thickness, thickness of the photoreceptor and outer nuclear layers, and loss of ganglion cells significantly improved in the retina of the DG-treated T2D mice compared with those in the PBS-treated T2D mice. Cleaved caspase-3 level significantly decreased in the retina of the DG-treated T2D mice. Conclusion: DG alleviates DR pathology and exerts a protective effect on the T2D mouse retina. The inhibitory effects of DG on DR may involve mechanisms of the anti-apoptotic pathway.

VEGF promotes diabetic retinopathy by upregulating the PKC/ET/NF-κB/ICAM-1 signaling pathway.

Diabetic retinopathy (DR) is a common microvascular complication in patients with diabetes mellitus. DR is caused by chronic hyperglycemia and is characterized by progressive loss of vision because of damage to the retinal microvasculature. In this study, we investigated the regulatory role and clinical significance of the vascular endothelial growth factor (VEGF)/protein kinase C (PKC)/endothelin (ET)/nuclear factor-κB (NF-κB)/intercellular adhesion molecule 1 (ICAM-1) signaling pathway in DR using a rat model. Intraperitoneal injections of the VEGF agonist, streptozotocin (STZ) were used to generate the DR model rats. DR rats treated with the VEGF inhibitor (DR+VEGF inhibitor) were used to study the specific effects of VEGF on DR pathology and the underlying mechanisms. DR and DR+VEGF agonist rats were injected with the PKCβ2 inhibitor, GF109203X to determine the therapeutic potential of blocking the VEGF/PKC/ET/NF-κB/ICAM-1 signaling pathway. The body weights and blood glucose levels of the rats in all groups were evaluated at 16 weeks. DR-related retinal histopathology was analyzed by hematoxylin and eosin staining. ELISA assay was used to estimate the PKC activity in the retinal tissues. Western blotting and RT-qPCR assays were used to analyze the expression levels of PKC-β2, VEGF, ETs, NF-κB, and ICAM-1 in the retinal tissues. Immunohistochemistry was used to analyze VEGF and ICAM-1 expression in the rat retinal tissues. Our results showed that VEGF, ICAM-1, PKCβ2, ET, and NF-κB expression levels as well as PKC activity were significantly increased in the retinal tissues of the DR and DR+VEGF agonist rat groups compared to the control and DR+VEGF inhibitor rat groups. DR and DR+VEGF agonist rats showed significantly lower body weight and significantly higher retinal histopathology scores and blood glucose levels compared to the control and DR+VEGF inhibitor group rats. However, treatment of DR and DR+VEGF agonist rats with GF109203X partially alleviated DR pathology by inhibiting the VEGF/ PKC/ET/NF-κB/ICAM-1 signaling pathway. In summary, our data demonstrated that inhibition of the VEGF/ PKC/ET/NF-κB/ICAM-1 signaling pathway significantly alleviated DR-related pathology in the rat model. Therefore, VEGF/PKC/ET/NF-κB/ICAM-1 signaling axis is a promising therapeutic target for DR.

Transforming Confocal Microscopy Imaging Data of Retinal Vasculature into 3D Animation.

This research study presents a methodology for creation of 3D models from confocal microscopy, specifically the retinal trilaminar capillary network, that can be used in 3D biomedical animation. Biomedical visualization professionals regularly use CT and MRI imaging data to create 3D models and other visuals. Adding confocal microscopy to this toolkit using ImageJ FIJI1 and Materialise Mimics® allows for a wider range of options to create data-driven 3D models of microscopic structures. Understanding the interactions of the neurovascular unit through visualization may be a key to advancing understanding of normal function of the retina and diabetic retinopathy pathology. This Vesalius Trust research poster was presented at the Association of Medical Illustrators' 2021 virtual annual meeting.

Ophthalmic Telemedicine in the Pandemic–Endemic World: Present and Future Perspectives

COVID-19 restrictions have increased the need and use of telemedicine in ophthalmology but this approach requires remote data collection and reliable technologies to ensure accurate and safe examination and diagnosis. This article reviews the existing telemedicine technologies for age-related macular degeneration (AMD), diabetic retinopathy (DR) and paediatric ophthalmology, and discusses their applicability in the COVID-19 era. We conducted a literature search of PubMed using telemedicine keywords for all relevant pathologies (AMD, DR and paediatric ophthalmology) to identify English-language articles published between 2001 and 2021. We assessed whether existing telemedicine technologies would meet the needs of patients under COVID-19 restrictions. Our findings showed that there are reliable existing home-monitoring technologies. However, self-operated home optical coherence tomography is still an investigational technology for AMD monitoring and is not yet available for routine use. Computerized algorithms aimed at identifying DR pathology and or deterioration in relevant parameters under investigation have shown excellent results. In paediatric ophthalmology, parents can conduct basic testing of their child's ophthalmic parameters; improvements in parental testing will require the development of quick and reliable automatic instruments. In conclusion, current technologies lend themselves to remote use for ophthalmic examination by non-professional individuals, which is particularly relevant for ophthalmic care provision in the pandemic setting. Further investigative effort is needed in order to improve home monitoring and computerized data processing.

670nm photobiomodulation modulates bioenergetics and oxidative stress, in rat Müller cells challenged with high glucose.

Diabetic retinopathy (DR), the most common complication of diabetes mellitus, is associated with oxidative stress, nuclear factor-κB (NFκB) activation, and excess production of vascular endothelial growth factor (VEGF) and intracellular adhesion molecule-1 (ICAM-1). Muller glial cells, spanning the entirety of the retina, are involved in DR inflammation. Mitigation of DR pathology currently occurs via invasive, frequently ineffective therapies which can cause adverse effects. The application of far-red to near-infrared (NIR) light (630-1000nm) reduces oxidative stress and inflammation in vitro and in vivo. Thus, we hypothesize that 670nm light treatment will diminish oxidative stress preventing downstream inflammatory mechanisms associated with DR initiated by Muller cells. In this study, we used an in vitro model system of rat Müller glial cells grown under normal (5 mM) or high (25 mM) glucose conditions and treated with a 670 nm light emitting diode array (LED) (4.5 J/cm2) or no light (sham) daily. We report that a single 670 nm light treatment diminished reactive oxygen species (ROS) production and preserved mitochondrial integrity in this in vitro model of early DR. Furthermore, treatment for 3 days in culture reduced NFκB activity to levels observed in normal glucose and prevented the subsequent increase in ICAM-1. The ability of 670nm light treatment to prevent early molecular changes in this in vitro high glucose model system suggests light treatment could mitigate early deleterious effects modulating inflammatory signaling and diminishing oxidative stress.

Segmentation in Diabetic Retinopathy using Deeply-Supervised Multiscalar Attention.

Diabetic Retinopathy (DR) is a progressive chronic eye disease that leads to irreversible blindness. Detection of DR at an early stage of the disease is crucial and requires proper detection of minute DR pathologies. A novel Deeply-Supervised Multiscale Attention U-Net (Mult-Attn-U-Net) is proposed for segmentation of different DR pathologies viz. Microaneurysms (MA), Hemorrhages (HE), Soft and Hard Exudates (SE and EX). A publicly available dataset (IDRiD) is used to evaluate the performance. Comparative study with four state-of-the-art models establishes its superiority. The best segmentation accuracy obtained by the model for MA, HE, SE are 0.65, 0.70, 0.72, respectively.

Dissecting the Pathogenesis of Diabetic Retinopathy Based on the Biological ceRNA Network and Genome Variation Disturbance.

Background Diabetic retinopathy (DR) is the most important manifestation of diabetic microangiopathy. It is essential to explore the gene regulatory relationship and genomic variation disturbance of biological networks in DR progression. Methods In this study, we constructed a comprehensive lncRNA-mRNA ceRNA network of DR procession (CLMN) and explored its topological characteristics. Results Modular and functional analysis indicated that the organization of CLMN performed fundamental and specific functions in diabetes and DR pathology. The differential expression of hub ceRNA nodes and positive correlation reveals the highly connected ceRNA regulation and important roles in the regulating of DR pathology. A large proportion of SNPs in the TFBS, DHS, and enhancer regions of lncRNAs will affect lncRNA transcription and further cause expression variation. Some SNPs were found to disrupt the lncRNA functional elements such as miRNA target binding sites. These results indicate the complex nature of genotypic effects in the disturbing of CLMN and further contribute to gene expression variation and different disease phenotypes. Conclusion The identification of individual genomic variations and analysis of biological network disturbance by these genomic variations will help provide more personalized treatment plans and promote the development of precision medicine for DR.

TRIM46 contributes to high glucose-induced ferroptosis and cell growth inhibition in human retinal capillary endothelial cells by facilitating GPX4 ubiquitination

PurposeIncreased permeability of retinal capillary endothelial cells is a key feature in the progression of diabetic retinopathy (DR). Precisely why and how diabetes causes dysfunction in retinal capillary endothelial cells is not well understood, making it challenging to explore more advanced therapeutics. MethodsCell proliferation was assessed by the Cell Counting Kit-8 assay. Ferroptosis was evaluated by measuring lipid reactive oxygen species levels by flow cytometry and determining malondialdehyde, superoxide dismutase, and glutathione peroxidase levels through biochemical assays. Western blot analysis and quantitative PCR were respectively used to check the expression of proteins and RNAs. Co-immunoprecipitation assays were used to confirm the interaction between TRIM46 and GPX4. ResultsHigh glucose (HG, 25 mM glucose) significantly suppressed cell growth, which could be reversed by the ferroptosis inhibitor, ferrostatin-1. HG treatment time-dependently induced ferroptosis in human retinal capillary endothelial cells (HRCECs) and induced TRIM46 expression. Lentiviral-mediated overexpression of TRIM46 decreased cell resistance against HG-induced ferroptosis, whereas knockdown showed the opposite effect. Administration of RSL3, a ferroptosis agonist, was able to reverse the protective effects of TRIM46 silencing. TRIM46 interacted with GPX4, an important enzyme that suppresses ferroptosis, and promoted GPX4 ubiquitination. Furthermore, lentiviral-mediated overexpression ofGPX4 ameliorated the effects of TRIM46 overexpression and conferred protection to cells against HG-induced ferroptosis. ConclusionTRIM46 and GPX4 form a regulatory pathway that controls HG-induced ferroptosis of HRCECs. Inhibiting this pathway or sustaining the expression of GPX4 enables cells to resist damage caused by HG. We provide new mechanistic insight into the pathology of DR and identified TRIM46 and GPX4 as two molecular targets for the development of effective drugs for DR treatment.