Oxidative Stress and Microvascular Alterations in Diabetic Retinopathy: Future Therapies.Oxid Med Cell Longev. 2019;2019:4940825. [PMID: 31814880 DOI: 10.1155/2019/4940825]

EfficientNetB0-Based End-to-End Diagnostic System for Diabetic Retinopathy Grading and Macular Edema Detection

Purpose

This study aims to develop and validate a deep learning-based automated diagnostic system that utilizes fluorescein angiography (FFA) images for the rapid and accurate diagnosis of diabetic retinopathy (DR) and its complications.

Methods

We collected 19,031 FFA images from 2753 patients between June 2017 and March 2024 to construct and evaluate our analytical framework. The images were preprocessed and annotated for training and validating the deep learning model. The study employed a two-stage deep learning system: the first stage used EfficientNetB0 for a five-class classification task to differentiate between normal retinal conditions, various stages of DR, and post-laser treatment status; the second stage focused on images classified as abnormal in the first stage, further detecting the presence of diabetic macular edema (DME). Model performance was evaluated using multiple classification metrics, including accuracy, AUC, precision, recall, F1-score, and Cohen's kappa coefficient.

Results

In the first stage, the model achieved an accuracy of 0.7036 and an AUC of 0.9062 on the test set, demonstrating high accuracy and discriminative ability. In the second stage, the model achieved an accuracy of 0.7258 and an AUC of 0.7530, performing well. Additionally, through Grad-CAM (gradient-weighted class activation mapping), we visualized the most influential image regions in the model's decision-making process, enhancing the model's interpretability.

Conclusion

This study successfully developed an end-to-end DR diagnostic system based on the EfficientNetB0 model. The system not only automates the grading of FFA images but also detects DME, significantly reducing the time required for image interpretation by clinicians and providing an effective tool to improve the efficiency and accuracy of DR diagnosis.

Correlations of Thioredoxin and Thioredoxin Interacting Protein with Type 2 Diabetes Mellitus Complicated with Diabetic Retinopathy

PURPOSE

To investigate the relationship between Thioredoxin (Trx), Thioredoxin interacting protein (Txnip), and the severity of diabetic retinopathy (DR).

METHODS

The study involved a total of 101 eyes, comprising of 31 healthy controls, 24 diabetic patients with no clinically detectable retinopathy (NDR group), 26 patients with non-proliferative DR (NPDR group), and 20 patients with proliferative DR (PDR group), including 62 males and 49 females, average aged 61.65 ± 9.4. Retinal morphology was evaluated using spectral domain optical coherence tomography (SD-OCT), while retinal function was assessed using full-field electroretinogram (ffERG) to record the amplitudes and implicit time. The correlation between serum Trx, Txnip, and DR was analyzed using Spearman correlation analysis.

RESULTS

In the early stage of DR, there was no significant difference in macular retinal thickness between groups; in the PDR group, there was a significant increase compared to both the NDR and control groups, particularly in the central fovea (p < 0.0001). Additionally, the amplitude and implicit time of oscillatory potentials exhibited a significant difference between the NDR and control groups at an early stage of DR (p < 0.001). Furthermore, the amplitude of rod and cone ERG decreased significantly in the early stage of DR, while the implicit time began to decline in the NPDR stage. The serum levels of Trx and Txnip exhibited a positive correlation with the progression of DR (r = 0.851, 0.762). Conversely, a negative correlation was observed between the serum levels of Trx and Txnip and the amplitudes of ERG, while a positive correlation was observed with the implicit time of ERG.

CONCLUSIONS

The serum levels of Trx and Txnip exhibit a positive correlation with retinopathy associated with type 2 diabetes mellitus (T2DM), and thus may be utilized as a potential target for the timely diagnosis and treatment of DR.

Natural remedies proposed for the management of diabetic retinopathy (DR): diabetic complications

Diabetic retinopathy (DR) represents a significant and serious complication associated with diabetes mellitus (DM), often resulting in considerable visual impairment or even blindness. The intricate pathological processes underlying DR complicate the effectiveness of current treatment modalities. Studies have highlighted the potential of natural products in the treatment of DR via several beneficial effects including anti-inflammatory, antioxidant, anti-neovascular, and anti-apoptotic properties. Flavonoids, saponins, saccharides, and alkaloids exhibited various beneficial effects in DR in in vivo and in vitro studies. However, the clinical utilization of these natural compounds is hindered by issues such as inadequate specificity, low bioavailability, and potential toxicity. Therefore, there is a pressing need for rigorous clinical studies to confirm the efficacy of natural products in preventing or mitigating the progression of DR.

Gene and phenome-based analysis of the shared genetic architecture of eye diseases

While many eye disorders are linked through defects in vascularization and optic nerve degeneration, genetic correlation studies have yielded variable results despite shared features. For example, glaucoma and myopia both share optic neuropathy as a feature, but genetic correlation studies demonstrated minimal overlap. By leveraging electronic health record (EHR) resources that contain genetic variables such as genetically predicted gene expression (GPGE), researchers have the potential to improve the identification of shared genetic drivers of disease by incorporating knowledge of shared features to identify disease-causing mechanisms. In this study, we examined shared genetic architecture across eye diseases. Our gene-based approach used transcriptome-wide association methods to identify shared transcriptomic profiles across eye diseases within BioVU, Vanderbilt University Medical Center's (VUMC's) EHR-linked biobank. Our phenome-based approach leveraged phenome-wide association studies (PheWASs) to identify eye disease comorbidities. Using the beta estimates from the significantly associated comorbidities, we constructed a phenotypic risk score (PheRS) representing a weighted sum of an individual's eye disease comorbidities. This PheRS is predictive of eye disease status and associated with the altered GPGE of significant genes in an independent population. The implementation of both gene- and phenome-based approaches can expand genetic associations and shed greater insight into the underlying mechanisms of shared genetic architecture across eye diseases.

Study on the mechanism of plant metabolites to intervene oxidative stress in diabetic retinopathy

Diabetic retinopathy is the main microvascular complication of diabetes and the first blinding eye disease in the working-age population. Oxidative stress is an important pathogenesis of diabetic retinopathy. Plant metabolites can be divided into two types: primary metabolites and secondary metabolites, secondary metabolites are the main active components and important sources for developing new drugs. It has unique effect in the treatment of diabetic retinopathy. However, the research on the intervention mechanism of plant metabolites in diabetic retinopathy are still relatively shallow, which limit the application of plant metabolites. With the deepening of research, more and more plant metabolites have been reported to play a role in treating diabetic retinopathy through anti-oxidative stress, including polyphenols, polysaccharides, saponins, alkaloids, etc. Therefore, this article reviewed the potential of plant metabolites in the treatment of diabetic retinopathy in the last 10 years and elucidated their mechanism of action. We hope to provide some references for the application of plant metabolites and provide valuable resources for the research and development of new drugs for diabetic retinopathy.

Positive association of large alcohol intake per occasion with vision-threatening severe diabetic retinopathy or diabetic macular edema in Japanese men with type 2 diabetes

OBJECTIVE

Differing from the overall consumption of alcohol, whether consuming large quantities of alcohol per drinking occasion is associated with higher risk of developing severe diabetic retinopathy remains unknown.

METHODS

We examined whether the quantity per drinking occasion (QPO), including a large QPO, and the combinations of the frequency of alcohol consumption (FAC) and QPO were associated with higher risk of developing severe diabetic retinopathy or diabetic macular edema (DME) using adjusted Cox models. Severe diabetic retinopathy or DME was designated as a vision-threatening treatment-required diabetic eye disease (TRDED). For each man with type 2 diabetes who participated in this longitudinal retrospective cohort study, the date of the earliest health check-up during the inclusion period (April 2008 to August 2016) was set as the start date of follow-up.

RESULTS

A TRDED was observed in 425 of 21,392 Japanese men aged 22-74 years with type 2 diabetes during a mean follow-up of 4.3 years (4.6/1000 person-years). Multivariable Cox analysis showed that a large QPO, defined as drinking three drinks or more per occasion, in low- (hazard ratio [HR], 4.76; 95 % CI, 2.06-10.97), intermediate- (HR, 1.58; 95 %CI, 1.001-2.50), and high-frequency categories (HR, 2.01; 95 % CI, 1.20-3.36) was significantly associated with elevated risks of TRDED.

CONCLUSIONS

In addition to the total amount of ethanol, these findings imply the necessity of avoiding the consumption of large amounts of alcohol on a single occasion to prevent severe diabetic retinopathy or DME.

Capsiate Improves Glucose Metabolism by Improving Insulin Sensitivity in Diabetic Retinopathy Mice

PURPOSE

Capsiate (cap) is a metabolite that affects a number of biological processes, and diabetic retinopathy (DR) is now known to be the primary cause of end-stage eye illness.

METHODS

In order to examine the effects of the cap intervention on body weight, nutritional intake, changes in body weight composition, glucose metabolism levels, retinopathy, and oxidative stress levels, we proposed using a mouse model of diabetic retinopathy caused by STZ.

RESULTS

Our findings demonstrated that, in addition to increasing lean body mass and lowering fat body mass content, cap intervention significantly improved body weight and dietary consumption in STZ mice. Additionally, our results on glucose metabolism revealed that cap had a significant impact on insulin resistance and the stabilization of OGTT levels. In conclusion, we examined the levels of oxidative stress and retinopathy. We discovered that the cap intervention greatly reduced the levels of MDA and significantly improved the levels of VEGF and retinopathy. In contrast, the STZ group's levels of SOD, CAT, and GSH were significantly higher.

CONCLUSIONS

According to our research, the Cap intervention improved the damage caused by diabetic retinopathy by reversing the levels of oxidative stress and the disrupted state of glucose metabolism, which in turn decreased the levels of VEGF.

SIRT3 mitigates high glucose-induced damage in retinal microvascular endothelial cells via OPA1-mediated mitochondrial dynamics

Oxidative stress in endothelial cells is pivotal in diabetic retinopathy (DR), with mitochondrial homeostasis being crucial to mitigate this stress. This study explored the roles of mitochondrial sirtuins (SIRTs) in high glucose (HG)-induced oxidative stress, related endothelial impairment, and mitochondrial homeostasis damage in rat retinal microvascular endothelial cells (RMECs). RMECs were cultured under HG or equivalent osmotic conditions. Cell viability was assessed using the Cell Counting Kit-8 assay, whereas cell death and survival were determined via calcein-AM/propidium iodide double staining. Reactive oxygen species (ROS) levels were measured using 2',7'-dichlorofluorescein fluorescence. Expression of mitochondrial SIRTs3-5 and key mitochondrial homeostasis molecules was quantified by the quantitative real-time polymerase chain reaction and confirmed by western blotting. Mitochondrial morphology was evaluated using electron microscopy and the MitoTracker fluorescent probe. A SIRT3-overexpressing RMEC line was constructed to assess the role of SIRT3 in oxidative stress and mitochondrial dynamics. After 48 h of HG exposure, cell viability was significantly reduced, with a concomitant increase in cell death and ROS levels, alongside a marked decrease in SIRT3 expression and molecules associated with mitochondrial dynamics. SIRT3 overexpression reversed these effects, particularly increasing the mitochondrial fusion-related molecule, optic atrophy 1 (OPA1). However, the OPA1 inhibitor, MYLS22, blocked the protective effect of SIRT3, leading to more dead cells, a higher ROS level, and intensified mitochondrial fragmentation. These results suggest that SIRT3 is involved in HG-induced imbalanced mitochondrial dynamics of endothelial cells in DR, potentially through the OPA1 pathway.

Challenging directions in pediatric diabetes - the place of oxidative stress and antioxidants in systemic decline

Diabetes is a complex condition with a rising global incidence, and its impact is equally evident in pediatric practice. Regardless of whether we are dealing with type 1 or type 2 diabetes, the development of complications following the onset of the disease is inevitable. Consequently, contemporary medicine must concentrate on understanding the pathophysiological mechanisms driving systemic decline and on finding ways to address them. We are particularly interested in the effects of oxidative stress on target cells and organs, such as pancreatic islets, the retina, kidneys, and the neurological or cardiovascular systems. Our goal is to explore, using the latest data from international scientific databases, the relationship between oxidative stress and the development or persistence of systemic damage associated with diabetes in children. Additionally, we highlight the beneficial roles of antioxidants such as vitamins, minerals, polyphenols, and other bioactive molecules; in mitigating the pathogenic cascade, detailing how they intervene and their bioactive properties. As a result, our study provides a comprehensive exploration of the key aspects of the oxidative stress-antioxidants-pediatric diabetes triad, expanding understanding of their significance in various systemic diseases.

Underlying mechanisms of traditional Chinese medicine in the prevention and treatment of diabetic retinopathy: Evidences from molecular and clinical studies

As one of the most serious microvascular complications of diabetes mellitus (DM), diabetic retinopathy (DR) can cause visual impairment and even blindness. With the rapid increase in the prevalence of DM, the incidence of DR is also rising year by year. Preventing and effectively treating DR has become a major focus in the medical field. Traditional Chinese medicine (TCM) has a wealth of experience in treating DR and has achieved significant results with various herbs and TCM prescriptions. Traditional Chinese Medicine (TCM) provides a comprehensive therapeutic strategy for diabetic retinopathy (DR), encompassing anti-inflammatory and antioxidant actions, anti-neovascularization, neuroprotection, regulation of glucose metabolism, and inhibition of apoptosis. This review provides an overview of the current status of TCM treatment for DR in recent years, including experimental studies and clinical researches, to explore the clinical efficacy and the underlying modern mechanisms of herbs and TCM prescriptions. Besides, we also discussed the challenges TCM faces in treating DR, such as drug-drug interactions among TCM components and the lack of high-quality evidence-based medicine practice, which pose significant obstacles to TCM's application in DR.

Role of oxidative stress in diabetes-induced complications and their management with antioxidants

Diabetes mellitus (DM) is a huge global health issue and one of the most studied diseases, with a large global prevalence. Oxidative stress is a cytotoxic consequence of the excessive development of ROS and suppression of the antioxidant defense system for ROS elimination, which accelerates the progression of diabetes complications such as diabetic neuropathy, retinopathy, and nephropathy. Hyperglycaemia induced oxidative stress causes the activation of seven major pathways implicated in the pathogenesis of diabetic complications. These pathways increase the production of ROS and RNS, which contributes to dysregulated autophagy, gene expression changes, and the development of numerous pro-inflammatory mediators which may eventually lead to diabetic complications. This review will illustrate that oxidative stress plays a vital role in the pathogenesis of diabetic complications, and the use of antioxidants will help to reduce oxidative stress and thus may alleviate diabetic complications.

Diabetes and the associated complications: The role of antioxidants in diabetes therapy and care

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by high blood sugar levels (hyperglycemia). Poorly managed diabetes can lead to complications affecting multiple organ systems. Antioxidants play a crucial role in reducing oxidative stress caused by reactive oxygen species (ROS), primarily triggered by uncontrolled high blood sugar levels in diabetes. Antioxidants like vitamin C, E, selenium, and alpha-lipoic acid, when used as supplements, have shown promise in reducing oxidative stress markers and improving antioxidant status in laboratory and animal studies and diabetic patients. Antioxidant supplementation may help reduce the risk of diabetic complications such as neuropathy, nephropathy, retinopathy, and cardiovascular disease. Additionally, antioxidants also have anti-inflammatory properties, which could be beneficial in reducing inflammation associated with diabetes. Antioxidant supplementation has been shown to enhance endothelial function, insulin sensitivity, and glucose metabolism, thereby aiding in glycemic control and overall diabetic management. Combining antioxidants with certain medications may have therapeutic benefits, such as effectively neutralizing free radicals and enhancing the regulation of antioxidant defense systems. This review presents an update on diabetes, the sources of free radical generation, the body's natural defense mechanisms, the clinical evidence regarding using antioxidants in managing diabetic complications, and the potential new therapeutic approaches. Overall, antioxidant supplementation may offer some benefits in managing diabetic complications. However, further studies are needed to understand the mechanisms of action, determine the optimal supplementation, explore potential interactions with other medications, and conduct long-term studies to establish the possible use of antioxidants for optimal benefits in diabetes care.

Impact of fluorosis on molecular predictors in pathogenesis of type 2 diabetes associated microvascular complications

AIM

This review presents specific insights on the molecular underpinnings of the connection between fluorosis, type 2 diabetes, and microvascular complications, along with the novel biomarkers that are available for early detection.

SUMMARY

Fluoride is an essential trace element for the mineralization of teeth and bones in humans. Exposure to higher concentrations of fluoride has harmful effects that significantly outweigh its advantageous ones. Dental fluorosis and skeletal fluorosis are the common side effects of exposure to fluoride, which affect millions of individuals globally. Alongside, it also causes non-skeletal fluorosis, which affects the population suffering from non-communicable diseases like diabetes by impacting the soft tissues and causing diabetic microvascular complications. Previous studies reported the prevalence range of these diabetic complications of neuropathy (3-65 %), nephropathy (1-63 %), and retinopathy (2-33 %). Fluoride contributes to the development of these complications by causing oxidative stress, cellular damage, degrading the functioning capability of mitochondria, and thickening the retinal vein basement.

CONCLUSION

Early diagnosis is a prompt way of prevention, and for that, biomarkers have emerged as an innovative and useful technique. This allows healthcare practitioners and policymakers in endemic areas to comprehend the molecular complexities involved in the advancement of diabetic microvascular problems in the context of high fluoride exposure.

Role of ferroptosis in mitochondrial damage in diabetic retinopathy

Diabetic retinopathy is driven by oxidative stress-mitochondrial damage. Activation of ROS producing cytosolic NADPH oxidase 2 (Nox2) in diabetes precedes retinal mitochondrial damage, initiating a vicious cycle of free radicals. Elevated ROS levels peroxidize membrane lipids increasing damaging lipid peroxides (LPOs). While glutathione peroxidase 4 (GPx4) neutralizes LPOs, an imbalance in its generation-neutralization leads to ferroptosis, which is characterized by increased LPOs, free iron and decreased GPx4 activity. Mitochondria are rich in polyunsaturated fatty acids and iron and have mitochondrial isoform of GPx4. Our aim was to investigate mitochondrial ferroptosis in diabetic retinopathy, focusing on Nox2 mediated ROS production. Using human retinal endothelial cells, incubated in 5 mM or 20 mM D-glucose for 12-96 h, with or without Nox2 inhibitors (100 μM apocynin, 5 μM EHop-016 or 5 μM Gp91 ds-tat), or ferroptosis inhibitors (1 μM ferrostatin-1, 50 μM deferoxamine) or activator (0.1 μM RSL3), cytosolic and mitochondrial ROS, LPOs, iron, GPx4 activity, mitochondrial integrity (membrane permeability, oxygen consumption rate, mtDNA copy numbers) and cell death were quantified. High glucose significantly increased ROS, LPOs and iron levels and inhibited GPx4 activity in cytosol, and while Nox2 and ferroptosis inhibitors prevented glucose-induced increase in ferroptosis markers, mitochondrial damage and cell death, RSL3, further worsened them. Furthermore, high glucose also increased ferroptosis markers in the mitochondria, which followed their increase in the cytosol, suggesting a role of cytosolic ROS in mitochondrial ferroptosis. Thus, targeting Nox2-ferroptosis should help break down the self-perpetuating vicious cycle of free radicals, initiated by the damaged mitochondria, and could provide novel therapeutics to prevent/retard the development of diabetic retinopathy.

Autophagy-dependent ferroptosis may play a critical role in early stages of diabetic retinopathy

Diabetic retinopathy (DR), as one of the most common and significant microvascular complications of diabetes mellitus (DM), continues to elude effective targeted treatment for vision loss despite ongoing enrichment of the understanding of its pathogenic mechanisms from perspectives such as inflammation and oxidative stress. Recent studies have indicated that characteristic neuroglial degeneration induced by DM occurs before the onset of apparent microvascular lesions. In order to comprehensively grasp the early-stage pathological changes of DR, the retinal neurovascular unit (NVU) will become a crucial focal point for future research into the occurrence and progression of DR. Based on existing evidence, ferroptosis, a form of cell death regulated by processes like ferritinophagy and chaperone-mediated autophagy, mediates apoptosis in retinal NVU components, including pericytes and ganglion cells. Autophagy-dependent ferroptosis-related factors, including BECN1 and FABP4, may serve as both biomarkers for DR occurrence and development and potentially crucial targets for future effective DR treatments. The aforementioned findings present novel perspectives for comprehending the mechanisms underlying the early-stage pathological alterations in DR and open up innovative avenues for investigating supplementary therapeutic strategies.

Polysaccharides from Ostrea rivularis alleviate type II diabetes induced-retinopathy and VGEF165-induced angiogenesis via PI3K/AKT signaling pathway

The purpose of this study was to investigate the role of polysaccharides from Ostrea rivularis Gloud (ORPs) in the progression of diabetic retinopathy (DR) and its anti-angiogenic effect on endothelial cell. Transgenic db/db mice with DR model were used to evaluate the protective effect of ORPs on retinal damage. It was found that ORPs could down-regulated levels of random blood glucose and fasting insulin, and further ameliorate retinal structure abnormalities as well as vascular network structure. Moreover, ORPs could reduce the expression of VEGF in retinal tissue and lessen pathological angiogenesis, thus slowing the progression of DR. In vitro, the proliferation, migration and tube formation of VGEF165-induced EA.hy926 cells were inhibited with ORPs administration. Furthermore, the expression of related proteins in the PI3K/AKT pathway and angiogenesis related factors were improved after ORPs intervention. Overall, these findings suggested that ORPs could effectively control the development of DR, and inhibit VGEF165-induced EA.hy926 cells proliferation, migration and tube formation, which effects might work through blocking the activation of PI3K/AKT signaling pathway.

Ets2 Exacerbates Diabetic Retinopathy by Aggravating the Proliferation of Endothelial Cells and Inflammatory Response

Proliferative diabetic retinopathy (PDR), the most common type of diabetic retinopathy, is a main cause of visual and impairment blindness. Abnormal neovascularization, endothelial dysfunction, and vascular inflammation are important mechanisms for the development of PDR. Ets2 regulates angiogenesis-related genes and inflammation, however, the effect of Ets2 in PDR procession has not been clarified. Thus, this study is performed to investigate whether Ets2 exerts key functions in PDR. In this study, 10-week-old mice were used for establishing STZ-induced diabetic mice, and Ets2 expression was analyzed in retina tissues. Besides, newborn mice were applied to construct oxygen-induced retinopathy (OIR) models. The Ets2 expression, oxidative stress, and inflammation were detected in retina tissues. We found that Ets2 was highly expressed in retina tissues both in diabetic mice and OIR mice. Oxidative stress and inflammatory processes are two factors contributing to the pathogenesis of PDR. In retinal tissues of OIR mice, Ets2 knockdown inhibited expression of inflammatory mediators VEGFA, IL-6, and IL-8, and biomarkers of oxidative stress MCP-1, VCAM-1, and iNOS. ROS production was also inhibited by silencing Ets2. Ets2 deficiency inhibited endothelial cell proliferation in the retina. Furthermore, Ets2 knockdown contributed to suppressing the expression of angiogenesis-related genes VEGFA, JUNB, MMP-9, Tie2, Ang-2, and EphB4. Our study highlights that Ets2 accelerates PDR procession by promoting the proliferation of endothelial cells, oxidative stress, and inflammation, which provides a novel target against PDR.

PSAT1 is upregulated by METTL3 to attenuate high glucose-induced retinal pigment epithelial cell apoptosis and oxidative stress

BACKGROUND

Diabetic retinopathy (DR) is a major ocular complication of diabetes mellitus, and a significant cause of visual impairment and blindness in adults. Phosphoserine aminotransferase 1 (PSAT1) is an enzyme participating in serine synthesis, which might improve insulin signaling and insulin sensitivity. Furthermore, it has been reported that the m6A methylation in mRNA controls gene expression under many physiological and pathological conditions. Nevertheless, the influences of m6A methylation on PSAT1 expression and DR progression at the molecular level have not been reported.

METHODS

High-glucose (HG) was used to treat human retinal pigment epithelial cells (ARPE-19) to construct a cell injury model. PSAT1 and Methyltransferase-like 3 (METTL3) levels were detected by real-time quantitative polymerase chain reaction (RT-qPCR). PSAT1, B-cell lymphoma-2 (Bcl-2), Bcl-2 related X protein (Bax), and METTL3 protein levels were examined by western blot assay. Cell viability and apoptosis were detected by Cell Counting Kit-8 (CCK-8) and TUNEL assays. Reactive oxygen species (ROS), malondialdehyde (MDA), and Glutathione peroxidase (GSH-Px) levels were examined using special assay kits. Interaction between METTL3 and PSAT1 was verified using methylated RNA immunoprecipitation (MeRIP) and dual-luciferase reporter assay.

RESULTS

PSAT1 and METTL3 levels were decreased in DR patients and HG-treated ARPE-19 cells. Upregulation of PSAT1 might attenuate HG-induced cell viability inhibition and apoptosis and oxidative stress promotion in ARPE-19 cells. Moreover, PSAT1 was identified as a downstream target of METTL3-mediated m6A modification. METTL3 might improve the stability of PSAT1 mRNA via m6A methylation.

CONCLUSION

METTL3 might mitigate HG-induced ARPE-19 cell damage partly by regulating the stability of PSAT1 mRNA, providing a promising therapeutic target for DR.

Fetuin-B Interacts With Insulin Receptor-β and Promotes Insulin Resistance in Retina Cells

Purpose

The purpose of this study was to investigate the correlation between insulin and Fetuin-B (FETUB) and the influence of FETUB on insulin signaling pathway in diabetic retinopathy (DR).

Methods

Enzyme-linked immunosorbent assay (ELISA) was used to analyze FETUB and insulin levels in the serum and aqueous fluid of patients with DR and healthy controls. Quantitative PCR (q-PCR), Western blotting, and ELISA were used to examine FETUB expression in ARPE-19, BV2, and Müller cells under insulin stimulation. Co-immunoprecipitation was used to investigate the interaction of FETUB with insulin receptor-β (IRβ). Insulin resistance (IR)-BV2 and IR-Müller cells were treated with FETUB recombinant protein or FETUB short hairpin RNA (shRNA) to explore the influence of FETUB on insulin signaling pathway in DR. LY294002 (a PI3K pathway inhibitor) was used to determine whether FETUB affects glucose metabolism via the PI3K/Akt pathway.

Results

In aqueous fluid, FETUB concentrations were positively correlated with insulin levels. FETUB expression increased in Müller and BV2 cells under insulin regulation, and FETUB interacted with IRβ in retinal cells and mice retina. The interaction between IRβ and FETUB increased in BV2 and Müller cells under high-glucose than in controls. Insulin signaling pathway activation was suppressed in FETUB recombinant protein-treated BV2 and Müller cells but increased in FETUB shRNA-transfected cells. FETUB shRNA could not reverse LY294002-mediated inhibition of glucose transporter-4 expression.

Conclusions

Retinal cells are the source of insulin-regulated FETUB. The FETUB interacts with IRβ and affects insulin signaling pathway in BV2 and Müller cells. FETUB may aggravate IR in BV2 and Müller cells via the PI3K/Akt pathway.

Research Progress on the Role of Ubiquitination in Eye Diseases

The occurrence and development of ophthalmic diseases are related to the dysfunction of eye tissues. Ubiquitin is an important form of protein post-translational modification, which plays an essential role in the occurrence and development of diseases through specific modification of target proteins. Ubiquitination governs a variety of intracellular signal transduction processes, including proteasome degradation, DNA damage repair, and cell cycle progression. Studies have found that ubiquitin can play a role in eye diseases such as cataracts, glaucoma, keratopathy, retinopathy, and eye tumors. In this paper, the role of protein ubiquitination in eye diseases was reviewed.

The association between endometrial cancer and subsequent diabetic retinopathy severity: A retrospective nationwide study

OBJECTIVE

The endometrial cancer is a disorder with elevated oxidative stress. The high oxidative stress resulting from hyperglycemia can lead to diabetic retinopathy (DR) development which is a complication of type 2 diabetes mellitus. Accordingly, we aim to evaluate the potential relationship between the endometrial cancer and following DR development.

METHODS

A retrospective cohort study was conducted using the National Health Insurance Research Database (NHIRD) of Taiwan. Individuals diagnosed with endometrial cancer were matched to the non-endometrial cancer patients in a 1:4 ratio. The major outcomes are the presence of DR, diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR) according to diagnostic codes. Cox proportional hazard regression was used to show the adjusted hazard ratio (aHR) with 95% confidence interval (CI) of major outcomes between groups.

RESULTS

There were 99 (2.3%), 20 (0.5%), and 14 (0.3%) cases with DR, DME and PDR in the endometrial cancer group, respectively. Another 303 (1.8%), 35 (0.2%), and 27 (0.2%) with DR, DME and PDR were observed in the control group, respectively. The endometrial cancer group revealed a significantly higher incidence of DR compared with the control group (aHR 1.51, 95% CI 1.20-1.90, P < 0.001). The cumulative probability of DR was also higher in the endometrial cancer group than in the control group (P < 0.001). The relationship between endometrial cancer and DR was significantly higher in patients aged over 70 years (P = 0.008). In addition, a higher incidence of DR was found during the first 5 years after the endometrial cancer diagnosis (P < 0.001).

CONCLUSIONS

The endometrial cancer correlates to a higher incidence of subsequent DR, especially within first 5 years of endometrial cancer diagnosis.

In Vitro and in silico studies to explore potent antidiabetic inhibitor against human pancreatic alpha-amylase from the methanolic extract of the green microalga Chlorella vulgaris

Today's era and lifestyle have led to a quick rise in cases of diabetes. Diabetes mellitus (DM) has risen to the top of the list of serious diseases and stems from different health disorders. Human pancreatic alpha-amylase (HPA) enzyme plays a critical role in the digestion of carbohydrates, and inhibitors of alpha-amylase have been investigated as a way to slow the absorption of carbohydrates and reduce postprandial (after meal) hyperglycemia in patients with diabetes. Recently algal derivatives have been studied for their potential as a new drug against diabetes and other diseases. The study is aimed to find active biochemical compounds from the methanolic extract of Chlorella vulgaris. The in vitro studies were carried out and the results revealed that methanolic extract from C. vulgaris showed abundant inhibition efficacy of the α-amylase (IC50 of about 2.66 µg/mL) compared to acarbose (IC50 of about 2.85 µg/mL), a standard, commercial inhibitor. All the bioactive compounds from the methanolic extract were identified from the GCMS study and considered for in silico evaluation. Out of 14 bioactive compounds from GCMS, compound C3 showed higher docking energy (-8.3 kcal/mol) compared to other compounds. Subsequently, the comparative molecular dynamic simulation of apo and ligand-bound (compound C3 and acarbose) α-amylase complexes showed overall structural stability for compound C3 at the active site of α-amylase from various MD analyses. Hence, we believe, the bioactive compounds identified from GCMS may assist in diabetic therapeutics. Moreover, the compound C3 identified in this study could be a potential antidiabetic therapeutic inhibitor.Communicated by Ramaswamy H. Sarma.

Management of Microcomplications of Diabetes Mellitus: Challenges, Current Trends, and Future Perspectives in Treatment

Diabetes mellitus is a chronic metabolic disorder characterized by high blood sugar levels, which can lead to severe health issues if not managed effectively. Recent statistics indicate a significant global impact, with 463 million adults diagnosed worldwide and this projected to rise to 700 million by 2045. Type 1 diabetes is an autoimmune disorder where the immune system attacks pancreatic beta cells, reducing insulin production. Type 2 diabetes is primarily due to insulin resistance. Both types of diabetes are linked to severe microvascular and macrovascular complications if unmanaged. Microvascular complications, such as diabetic retinopathy, nephropathy, and neuropathy, result from damage to small blood vessels and can lead to organ and tissue dysfunction. Chronic hyperglycemia plays a central role in the onset of these complications, with prolonged high blood sugar levels causing extensive vascular damage. The emerging treatments and current research focus on various aspects, from insulin resistance to the intricate cellular damage induced by glucose toxicity. Understanding and intervening in these pathways are critical for developing effective treatments and managing diabetes long term. Furthermore, ongoing health initiatives, such as increasing awareness, encouraging early detection, and improving treatments, are in place to manage diabetes globally and mitigate its impact on health and society. These initiatives are a testament to the collective effort to combat this global health challenge.

MicroRNA-2861 regulates the proliferation and apoptosis of human retinal vascular endothelial cells treated with high glucose by targeting NDUFB7

Objectives

Although anti-VEGF and retinal laser photocoagulation are two therapeutic modalities that have been used in the clinical treatment of diabetic retinopathy (DR), it is unknown how these modalities target vascular endothelial function in DR.

Methods

We first downloaded and analyzed the differential genes in two DR-related datasets, GSE60436 and GSE53257. The differential gene expression was then verified using RT-qPCR, and the most upregulated gene, NDUFB7, was selected for subsequent experiments. Subsequently, the role of NDUFB7 silencing and enforced expression on the proliferation and apoptosis of HRVECs was explored using CCK-8 assay, EDU proliferation assay and apoptotic TUNEL staining. In addition, the upstream potential miRNAs of NDUFB7 were predicted online using the Targetscan website. RT-qPCR, Western blotting (WB), and dual luciferase gene reporter assay were used to confirm the targeting connection between miR-2861 and NDUFB7. Finally, miR-2861 expression after high glucose (HG) treatment and its effect on proliferation and apoptosis of HRVECs under HG were investigated.

Results

In this study, we first downloaded and analyzed the differential genes in two DR-related datasets, GSE60436 and GSE53257. We found that TUFM, PRELID1, MRPL32, NDUFB7, MRPL4, MRPL40, HSD17B10 and SLC25A13 were upregulated in DR, and RT-qPCR showed that NDUFB7 was most upregulated. Subsequent CCK-8 assay, EDU proliferation assay and TUNEL staining showed that up-picked NDUFB7 promotes proliferation and inhibits apoptosis of HRVECs. In addition, the upstream potential miRNAs of NDUFB7 were predicted online using the Targetscan website. RT-qPCR, Western blotting (WB), and dual luciferase gene reporter assay confirmed the targeting connection between miR-2861 and NDUFB7. Finally, it was observed that miR-2861 can inhibit the proliferation and promote the apoptosis of HRVECs by targeting NDUFB7.

Conclusions

Our findings showed that upregulated NDUFB7 in DR promotes proliferation and inhibits apoptosis of HRVECs, and miR-2861 can rescue the pathogenic effect of NDUFB7 upregulation by targeting NDUFB7.

Interleukin-10 deficiency induces thoracic perivascular adipose tissue whitening and vascular remodeling

Perivascular adipose tissue (PVAT) is an adipose layer, surrounding blood vessels, with a local modulatory role. Interleukin-10 (IL-10) has been shown to modulate vascular tissue. This study aimed to characterize the endogenous role of IL-10 in vascular remodeling, and PVAT phenotyping. Thoracic aortic segments from control (C57BL/6J) and IL-10 knockout (IL-10-/-) male mice were used. Analyzes of aorta/PVAT morphometry, and elastin, collagen and reticulin deposition were performed. Tissue uncoupling protein 1 (UCP1) was accessed by Western blotting. Endogenous absence of IL-10 reduced total PVAT area (p = 0.0310), and wall/lumen ratio (p = 0.0024), whereas increased vascular area and thickness (p < 0.0001). Total collagen deposition was augmented in IL-10-/-, but under polarized light, the reduction of collagen-I (p = 0.0075) and the increase of collagen-III (p = 0.0055) was found, simultaneously with reduced elastic fibers deposition (p = 0.0282) and increased deposition of reticular fibers (p < 0.0001). Adipocyte area was augmented in the IL-10 absence (p = 0.0225), and UCP1 expression was reduced (p = 0.0420). Moreover, relative frequency of white adipose cells and connective tissue was augmented in IL-10-/- (p < 0.0001), added to a reduction in brown adipose cells (p < 0.0001). Altogether, these data characterize aorta PVAT from IL-10-/- as a white-like adipocyte phenotype. Endogenous IL-10 prevents vascular remodeling and favors a brown-like adipocyte phenotype, suggesting a modulatory role for IL-10 in PVAT plasticity.

Innovative Nanotechnology in Drug Delivery Systems for Advanced Treatment of Posterior Segment Ocular Diseases

Funduscopic diseases, including diabetic retinopathy (DR) and age-related macular degeneration (AMD), significantly impact global visual health, leading to impaired vision and irreversible blindness. Delivering drugs to the posterior segment of the eye remains a challenge due to the presence of multiple physiological and anatomical barriers. Conventional drug delivery methods often prove ineffective and may cause side effects. Nanomaterials, characterized by their small size, large surface area, tunable properties, and biocompatibility, enhance the permeability, stability, and targeting of drugs. Ocular nanomaterials encompass a wide range, including lipid nanomaterials, polymer nanomaterials, metal nanomaterials, carbon nanomaterials, quantum dot nanomaterials, and so on. These innovative materials, often combined with hydrogels and exosomes, are engineered to address multiple mechanisms, including macrophage polarization, reactive oxygen species (ROS) scavenging, and anti-vascular endothelial growth factor (VEGF). Compared to conventional modalities, nanomedicines achieve regulated and sustained delivery, reduced administration frequency, prolonged drug action, and minimized side effects. This study delves into the obstacles encountered in drug delivery to the posterior segment and highlights the progress facilitated by nanomedicine. Prospectively, these findings pave the way for next-generation ocular drug delivery systems and deeper clinical research, aiming to refine treatments, alleviate the burden on patients, and ultimately improve visual health globally.

Interleukin-17A in diabetic retinopathy: The crosstalk of inflammation and angiogenesis

Diabetic retinopathy (DR) is a severe ocular complication of diabetes which can leads to irreversible vision loss in its late-stage. Chronic inflammation results from long-term hyperglycemia contributes to the pathogenesis and progression of DR. In recent years, the interleukin-17 (IL-17) family have attracted the interest of researchers. IL-17A is the most widely explored cytokine in IL-17 family, involved in various acute and chronic inflammatory diseases. Growing body of evidence indicate the role of IL-17A in the pathogenesis of DR. However, the pro-inflammatory and pro-angiogenic effect of IL-17A in DR have not hitherto been reviewed. Gaining an understanding of the pro-inflammatory role of IL-17A, and how IL-17A control/impact angiogenesis pathways in the eye will deepen our understanding of how IL-17A contributes to DR pathogenesis. Herein, we aimed to thoroughly review the pro-inflammatory role of IL-17A in DR, with focus in how IL-17A impact inflammation and angiogenesis crosstalk.

USP48 deubiquitination stabilizes SLC1A5 to inhibit retinal pigment epithelium cell inflammation, oxidative stress and ferroptosis in the progression of diabetic retinopathy

BACKGROUND

Diabetic retinopathy is one of the complications of diabetes mellitus. The aim of this study was to explore the effects of ubiquitin-specific protease 48 (USP48) and its underlying mechanisms in the development of diabetic retinopathy.

METHODS

CCK-8 assay, EdU assay, and flow cytometry were used to measure the proliferative ability and the apoptotic rate of ARPE-19 cells, respectively. ELISA kits were utilized to assess the levels of inflammatory cytokines. The levels of Fe2+, ROS and MDA were detected using the corresponding biochemical kits. The protein expression of USP48 and SLC1A5 was examined through western blot. The mRNA level of SLC1A5 was determined using RT-qPCR. The interaction relationship between USP48 and SLC1A5 was evaluated using Co-IP assay.

RESULTS

High glucose (HG) treatment significantly inhibited cell proliferation and elevated cell apoptosis, inflammation, ferroptosis and oxidative stress in ARPE-19 cells. HG treatment-caused cell damage was hindered by USP48 or SLC1A5 overexpression in ARPE-19 cells. Fer-1 treatment improved HG-caused cell damage in ARPE-19 cells, which was blocked by USP48 knockdown. Moreover, USP48 knockdown decreased SLC1A5 expression. SLC1A5 downregulation reversed the improvement effects of USP48 upregulation on cell damage in HG-treated ARPE-19 cells.

CONCLUSION

USP48 overexpression deubiquitinated SLC1A5 to elevate cell proliferation and suppress cell apoptosis, inflammation, ferroptosis and oxidative stress in HG-triggered ARPE-19 cells, thereby inhibiting the progression of diabetic retinopathy.

Possible retinotoxicity of long-term vardenafil treatment

Phosphodiesterase (PDE) inhibitors - such as vardenafil - are used primarily for treating erectile dysfunction via increasing cyclic guanosine monophosphate (cGMP) levels. Recent studies have also demonstrated their significant cardioprotective effects in several diseases, including diabetes, upon long-term, continuous application. However, PDE inhibitors are not specific for PDE5 and also inhibit the retinal isoform. A sustained rise in cGMP in photoreceptors is known to be toxic; therefore, we hypothesized that long-term vardenafil treatment might result in retinotoxicity. The hypothesis was tested in a clinically relevant animal model of type 2 diabetes mellitus. Histological experiments were performed on lean and diabetic Zucker Diabetic Fatty rats. Half of the animals were treated with vardenafil for six months, and the retinal effects were evaluated. Vardenafil treatment alleviated rod outer segment degeneration but decreased rod numbers in some positions and induced changes in the interphotoreceptor matrix, even in control animals. Vardenafil treatment decreased total retinal thickness in the control and diabetic groups and reduced the number of nuclei in the outer nuclear layer. Müller cell activation was detectable even in the vardenafil-treated control animals, and vardenafil did not improve gliosis in the diabetic group. Vardenafil-treated animals showed complex retinal alterations with improvements in some parameters while deterioration in others. Our results point towards the retinotoxicity of vardenafil, even without diabetes, which raises doubts about the retinal safety of long-term continuous vardenafil administration. This effect needs to be considered when approving PDE inhibitors for alternative indications.

Aqueous humor proteomics analyzed by bioinformatics and machine learning in PDR cases versus controls

BACKGROUND

To comprehend the complexities of pathophysiological mechanisms and molecular events that contribute to proliferative diabetic retinopathy (PDR) and evaluate the diagnostic value of aqueous humor (AH) in monitoring the onset of PDR.

METHODS

A cohort containing 16 PDR and 10 cataract patients and another validation cohort containing 8 PDR and 4 cataract patients were studied. AH was collected and subjected to proteomics analyses. Bioinformatics analysis and a machine learning-based pipeline called inference of biomolecular combinations with minimal bias were used to explore the functional relevance, hub proteins, and biomarkers.

RESULTS

Deep profiling of AH proteomes revealed several insights. First, the combination of SIAE, SEMA7A, GNS, and IGKV3D-15 and the combination of ATP6AP1, SPARCL1, and SERPINA7 could serve as surrogate protein biomarkers for monitoring PDR progression. Second, ALB, FN1, ACTB, SERPINA1, C3, and VTN acted as hub proteins in the profiling of AH proteomes. SERPINA1 was the protein with the highest correlation coefficient not only for BCVA but also for the duration of diabetes. Third, "Complement and coagulation cascades" was an important pathway for PDR development.

CONCLUSIONS

AH proteomics provides stable and accurate biomarkers for early warning and diagnosis of PDR. This study provides a deep understanding of the molecular mechanisms of PDR and a rich resource for optimizing PDR management.

Transient but not chronic hyperglycemia accelerates ocular glymphatic transport

Glymphatic transport is vital for the physiological homeostasis of the retina and optic nerve. Pathological alterations of ocular glymphatic fluid transport and enlarged perivascular spaces have been described in glaucomatous mice. It remains to be established how diabetic retinopathy, which impairs vision in about 50% of diabetes patients, impacts ocular glymphatic fluid transport. Here, we examined ocular glymphatic transport in chronic hyperglycemic diabetic mice as well as in healthy mice experiencing a daily transient increase in blood glucose. Mice suffering from severe diabetes for two and four months, induced by streptozotocin, exhibited no alterations in ocular glymphatic fluid transport in the optic nerve compared to age-matched, non-diabetic controls. In contrast, transient increases in blood glucose induced by repeated daily glucose injections in healthy, awake, non-diabetic mice accelerated antero- and retrograde ocular glymphatic transport. Structural analysis showed enlarged perivascular spaces in the optic nerves of glucose-treated mice, which were absent in diabetic mice. Thus, transient repeated hyperglycemic events, but not constant hyperglycemia, ultimately enlarge perivascular spaces in the murine optic nerve. These findings indicate that fluid transport in the mouse eye is vulnerable to fluctuating glycemic levels rather than constant hyperglycemia, suggesting that poor glycemic control drives glymphatic malfunction and perivascular enlargement in the optic nerve.

Red blood cells as biomarkers and mediators in complications of diabetes mellitus: A review

Red blood cells (RBCs), traditionally recognized for their oxygen transport role, have garnered increasing attention for their significance as crucial contributors to the pathophysiology of diabetes mellitus. In this comprehensive review, we elucidate the multifaceted roles of RBCs as both biomarkers and mediators in diabetes mellitus. Amidst the intricate interplay of altered metabolic pathways and the diabetic milieu, RBCs manifest distinct alterations in their structure, function, and lifespan. The chronic exposure to hyperglycemia induces oxidative stress, leading to modifications in RBC physiology and membrane integrity. These modifications, including glycation of hemoglobin (HbA1c), establish RBCs as invaluable biomarkers for assessing glycemic control over extended periods. Moreover, RBCs serve as mediators in the progression of diabetic complications. Their involvement in vascular dysfunction, hemorheological changes, and inflammatory pathways contributes significantly to diabetic microangiopathy and associated complications. Exploring the therapeutic implications, this review addresses potential interventions targeting RBC abnormalities to ameliorate diabetic complications. In conclusion, comprehending the nuanced roles of RBCs as biomarkers and mediators in diabetes mellitus offers promising avenues for enhanced diagnostic precision, therapeutic interventions, and improved patient outcomes. This review consolidates the current understanding and emphasizes the imperative need for further research to harness the full potential of RBC-related insights in the realm of diabetes mellitus.

Recent advances in the treatment and delivery system of diabetic retinopathy

Diabetic retinopathy (DR) is a highly tissue-specific neurovascular complication of type 1 and type 2 diabetes mellitus and is among the leading causes of blindness worldwide. Pathophysiological changes in DR encompass neurodegeneration, inflammation, and oxidative stress. Current treatments for DR, including anti-vascular endothelial growth factor, steroids, laser photocoagulation, and vitrectomy have limitations and adverse reactions, necessitating the exploration of novel treatment strategies. This review aims to summarize the current pathophysiology, therapeutic approaches, and available drug-delivery methods for treating DR, and discuss their respective development potentials. Recent research indicates the efficacy of novel receptor inhibitors and agonists, such as aldose reductase inhibitors, angiotensin-converting enzyme inhibitors, peroxisome proliferator-activated receptor alpha agonists, and novel drugs in delaying DR. Furthermore, with continuous advancements in nanotechnology, a new form of drug delivery has been developed that can address certain limitations of clinical drug therapy, such as low solubility and poor penetration. This review serves as a theoretical foundation for future research on DR treatment. While highlighting promising therapeutic targets, it underscores the need for continuous exploration to enhance our understanding of DR pathogenesis. The limitations of current treatments and the potential for future advancements emphasize the importance of ongoing research in this field.

Advances in Research Related to MicroRNA for Diabetic Retinopathy

Diabetic retinopathy (DR) is a severe microvascular complication of diabetes and is one of the primary causes of blindness in the working-age population in Europe and the United States. At present, no cure is available for DR, but early detection and timely intervention can prevent the rapid progression of the disease. Several treatments for DR are known, primarily ophthalmic treatment based on glycemia, blood pressure, and lipid control, which includes laser photocoagulation, glucocorticoids, vitrectomy, and antivascular endothelial growth factor (anti-VEGF) medications. Despite the clinical efficacy of the aforementioned therapies, none of them can entirely shorten the clinical course of DR or reverse retinopathy. MicroRNAs (miRNAs) are vital regulators of gene expression and participate in cell growth, differentiation, development, and apoptosis. MicroRNAs have been shown to play a significant role in DR, particularly in the molecular mechanisms of inflammation, oxidative stress, and neurodegeneration. The aim of this review is to systematically summarize the signaling pathways and molecular mechanisms of miRNAs involved in the occurrence and development of DR, mainly from the pathogenesis of oxidative stress, inflammation, and neovascularization. Meanwhile, this article also discusses the research progress and application of miRNA-specific therapies for DR.

Syringaresinol Alleviates Early Diabetic Retinopathy by Downregulating HIF-1α/VEGF via Activating Nrf2 Antioxidant Pathway

SCOPE

Early diabetic retinopathy (DR) is characterized by chronic inflammation, excessive oxidative stress, and retinal microvascular damage. Syringaresinol (SYR), as a natural polyphenolic compound, has been proved to inhibit many disease progression due to its antiinflammatory and antioxidant properties. The present study focuses on exploring the effect of SYR on hyperglycemia-induced early DR as well as the underlying mechanisms.

METHODS AND RESULTS

Wild-type (WT) and nuclear factor erythroid 2-related factor 2 (Nrf2)-knockout C57BL/6 mice of type 1 diabetes and high glucose (HG)-induced RF/6A cells are used as in vivo and in vitro models, respectively. This study finds that SYR protects the retinal structure and function in diabetic mice and reduces the permeability and apoptosis of HG-treated RF/6A cells. Meanwhile, SYR distinctly mitigates inflammation and oxidative stress in vivo and vitro. The retinal microvascular damages are suppressed by SYR via downregulating hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) pathway. Whereas, SYR-provided protective effects are diminished in Nrf2-knockout mice, indicating that SYR improves DR progression by activating Nrf2. Similarly, SYR cannot exert protective effects against HG-induced oxidative stress and endothelial injury in small interfering RNA (siRNA)-Nrf2-transfected RF/6A cells.

CONCLUSION

In summary, SYR suppresses oxidative stress via activating Nrf2 antioxidant pathway, which ameliorates retinal microvascular damage by downregulating HIF-1α/VEGF, thereby alleviating early DR progression.

Panax notoginseng saponins alleviate diabetic retinopathy by inhibiting retinal inflammation: Association with the NF-κB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetic retinopathy (DR) is a neurovascular disease that causes blindness in adults and is the most serious and common complication of diabetes mellitus. Retinal inflammation is an early stage of DR, and it is believed to play a crucial role in the development of DR. Panax notoginseng saponins (PNS) are the major active constituent in the main root of P. notoginseng, and they exhibit various biological activities, including anti-inflammatory, antioxidant, neuroprotective, and immunomodulatory functions. However, the protective effects and underlying mechanisms of PNS against DR remain unclear.

AIM OF THE STUDY

This study aimed to investigate the alleviation effects of PNS on DR and the mechanisms involved. Furthermore, it intended to explore the major components that exert efficacy in vivo.

MATERIALS AND METHODS

Streptozotocin (STZ) was administered intraperitoneally to Sprague Dawley rats, and PNS was administered orally for 1 month after 2 months of STZ injection. The morphological structure of the retina and retinal acellular capillaries were assessed via hematoxylin and eosin (H&E) staining assay. The disruption of the blood-retinal barrier (BRB) was detected through Evans blue dye leakage assay, and retinal leukocyte adhesion was achieved via fluorescein isothiocyanate-coupled concanavalin A lectin labeling assay. Immunofluorescence staining and Western blot assays were conducted to detect the expression of tight junction proteins, adhesion molecules, and the ionized calcium-binding adapter molecule-1 (Iba-1) in the retina. Enzyme-linked immunosorbent assay was performed to detect the levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β in serum. In addition, the protein expression levels of nuclear factor (NF)-κB p65, phosphorylated IκB kinase (p-IKK), phosphorylated NF-κB inhibitor (p-IκB), and phosphorylated NF-κB p65 (p-p65) were measured using Western blot assay. The ocular tissue distribution of PNS in normal and diabetic rats was determined through ultra-performance liquid chromatography-tandem mass spectrometry. The in vitro anti-inflammatory effects of PNS, notoginsenoside (NGR1), ginsenoside Rg1, Re, Rb1, and Rd (GRg1, GRe, GRb1, and GRd) were evaluated on human Müller (MIO-M1) cells.

RESULTS

PNS increased the reduction in retinal inner nuclear layer thickness, reduced the increase in retinal acellular capillaries, and attenuated elevated BRB disruption by upregulating the decrease in protein expression of claudin-1 and occludin. Furthermore, PNS significantly abrogated microglial cell activation and reversed the increase in leukocyte adhesion by downregulating the increase in the protein expression of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1. Moreover, PNS reduced the elevated levels of TNF-α, IL-6, and IL-1β in serum and inhibited the increased protein expression of p-IKK, p-IκB, and p-p65, and the nuclear translocation of p65. The tissue distribution results revealed that NGR1, GRg1, GRe, GRb1, and GRd were detected in the ocular tissue, while GRg1 and GRb1 were found at the highest levels compared with the other components. The cellular results showed that PNS, NGR1, GRg1, GRe, GRb1, and GRd suppressed the development of cellular inflammatory responses by inhibiting the activation of the NF-κB signaling pathway in MIO-M1 cells and that their anti-inflammatory effects were comparable.

CONCLUSION

PNS suppressed retinal inflammation by inhibiting the activation of the NF-κB signaling pathway, alleviating DR. GRg1 and GRb1 may be the primary components that exert anti-inflammatory effects in vivo.

Knockdown of ChREBP ameliorates retinal microvascular endothelial cell injury and angiogenic responses in diabetic retinopathy

PURPOSE

To examine whether and how carbohydrate response element-binding protein (ChREBP) plays a role in diabetic retinopathy.

METHODS

Western blotting was used to detect ChREBP expression and location following high glucose stimulation of Human Retinal Microvascular Endothelial Cells (HRMECs). Flow cytometry, TUNEL staining, and western blotting were used to evaluate apoptosis following ChREBP siRNA silencing. Cell scratch, transwell migration, and tube formation assays were used to determine cell migration and angiogenesis. Diabetic models for wild-type (WT) and ChREBP knockout (ChKO) mice were developed. Retinas of WT and ChKO animals were cultivated in vitro with vascular endothelial growth factor + high glucose to assess neovascular development.

RESULTS

ChREBP gene knockdown inhibited thioredoxin-interacting protein and NOD-like receptor family pyrin domain containing protein 3 expression in HRMECs, which was caused by high glucose stimulation, reduced apoptosis, hindered migration, and tube formation, and repressed AKT/mTOR signaling pathway activation. Compared with WT mice, ChKO mice showed suppressed high glucose-induced alterations in retinal structure, alleviated retinal vascular leakage, and reduced retinal neovascularization.

CONCLUSIONS

ChREBP deficiency decreased high glucose-induced apoptosis, migration, and tube formation in HRMECs as well as structural and angiogenic responses in the mouse retina; thus, it is a potential therapeutic target for diabetic retinopathy.

Association of lactate dehydrogenase and diabetic retinopathy in US adults with diabetes mellitus

OBJECTIVES

The purpose of our investigation is to evaluate the level of relationship between lactate dehydrogenase (LDH) and the occurrence of diabetic retinopathy (DR) in adults with diabetes mellitus (DM).

METHODS

The investigation involved an analysis of five sectional data cycles acquired from the National Health and Nutrition Examination Survey from 2009 to 2018. The present study involved the selection of DM samples from a complex multistage probability sample. These samples were subsequently classified into two distinct groups, namely the No DR (NDR) and DR groups. The present study comprehensively investigated the biological and social risk factors associated with DR. The biological factors examined in this investigation included blood pressure, blood routine, hemoglobin A1c, blood glucose, and comorbidities. The social dimensions encompass education and sex.

RESULTS

After considering all factors, multivariate regression models indicated a significant relationship between DR and increased LDH (adjusted odds ratio = 1.007, 95% confidence interval: 1.003-1.011). The subgroup analysis revealed that the effect size of LDH on the existence of DR in the subgroups remained consistent, as indicated by all p values greater than .05. A statistically significant relationship was identified between elevated LDH levels > 134 U/L and a raised risk of DR in people with DM.

CONCLUSION

LDH concentrations were connected with an increased prevalence of DR in participants with DM. Our study highlights that patients with LDH > 134 U/L are distinguishably related to DM complicated by DR. DR is more common in diabetic individuals with coronary heart disease.

Discussing pathologic mechanisms of Diabetic retinopathy & therapeutic potentials of curcumin and β-glucogallin in the management of Diabetic retinopathy

Diabetic retinopathy (DR) is a form of retinal microangiopathy that occurs as a result of long-term Diabetes mellitus (DM). Patients with Diabetes mellitus typically suffer from DR as a progression of the disease that may be due to initiation and dysregulation of pathways like the polyol, hexosamine, the AGE/RAGE, and the PKC pathway, which all have negative impacts on eye health and vision. In this review, various databases, including PubMed, Google Scholar, Web of Science, and Science Direct, were scoured for data relevant to the aforementioned title. The three most common therapies for DR today are retinal photocoagulation, anti-vascular endothelial growth factor (VEGF) therapy, and vitrectomy, however, there are a number of drawbacks and limits to these methods. So, it is of critical importance and profound interest to discover treatments that may successfully address the pathogenesis of DR. Curcumin and β-glucogallin are the two potent compounds of natural origin that are already being used in various nutraceutical formulations for several ailments. They have been shown potent antiapoptotic, anti-inflammatory, antioxidant, anticancer, and pro-vascular function benefits in animal experiments. Their parent plant species have been used for generations by practitioners of traditional herbal medicine for the treatment and prevention of various eye ailments. In this review, we will discuss about pathophysiology of Diabetic retinopathy and the therapeutic potentials of curcumin and β-glucogallin one of the principal compounds from Curcuma longa and Emblica officinalis in Diabetic retinopathy.

The circRNA MKLN1 regulates autophagy in the development of diabetic retinopathy

Diabetic retinopathy (DR) is a common complication in patients with diabetes and has become an important cause of blindness in working-age people. However, the mechanisms involved have not been fully elucidated. Circular RNAs (circRNAs) can play an important role in DR, and they can accurately regulate the expression of target genes through a new regulatory model: the competing endogenous RNA (ceRNA) model. We isolated total RNA from extracellular vesicles in the serum of healthy individuals (Con) and individuals with diabetes mellitus without DR (DM), nonproliferative DR (NPDR), or proliferative DR (PDR) and subjected them to deep sequencing. We found aberrantly high expression of circMKLN1. In a streptozotocin (STZ)-induced mice model of diabetes, the inhibition of circMKLN1 with AAV2 transduction markedly ameliorated retinal acellular vessels and vascular leakage, which was reversed by intravitreal injection of rapamycin, a potent autophagy inducer. In addition, circMKLN1 adsorbs miR-26a-5p as a molecular sponge and mediates high glucose (HG)/methylglyoxal (MG)-induced autophagy in hRMECs. CircMKLN1-silencing treatment reduces HG/MG-related reactive autophagy and inflammation. In addition, miR-26a-5p targeting by circMKLN1 plays an important role in the regulation of Rab11a expression. Thus, either new biomarkers or new therapeutic targets may be identified with the translation of these findings.

Probucol attenuates high glucose-induced Müller cell damage through enhancing the Nrf2/p62 signaling pathway

PURPOSE

This study investigated the protective effect of probucol on Müller cells exposed to high glucose conditions and examined potential mechanisms of action.

METHODS

Primary human retinal Müller cells were incubated with high glucose (HG, 35 mM) in the present or absence of different concentrations of probucol for 24 h. Cell viability was determined using the CCK-8 method. Mitochondrial membrane potential (MMP) was measured using JC-1 staining and cell cycle by flow cytometry. The expression of nuclear factor E2-related factor 2 (Nrf2), glutamate-cysteine ligase catalytic subunit, and p62 was quantified using quantitative polymerase chain reaction and western blot.

RESULTS

We found that HG inhibited cell proliferation, arrested cell cycle, and increased MMP in human Müller cells. Probucol activated the Nrf2/p62 pathway and upregulated the anti-apoptotic protein, Bcl2, and attenuated HG-mediated damage in Müller cells.

CONCLUSIONS

Our results suggest that probucol may protect Müller cells from HG-induced damage through enhancing the Nrf2/p62 signaling pathway.

Oxidative stress in the eye and its role in the pathophysiology of ocular diseases

Oxidative stress occurs through an imbalance between the generation of reactive oxygen species (ROS) and the antioxidant defense mechanisms of cells. The eye is particularly exposed to oxidative stress because of its permanent exposure to light and due to several structures having high metabolic activities. The anterior part of the eye is highly exposed to ultraviolet (UV) radiation and possesses a complex antioxidant defense system to protect the retina from UV radiation. The posterior part of the eye exhibits high metabolic rates and oxygen consumption leading subsequently to a high production rate of ROS. Furthermore, inflammation, aging, genetic factors, and environmental pollution, are all elements promoting ROS generation and impairing antioxidant defense mechanisms and thereby representing risk factors leading to oxidative stress. An abnormal redox status was shown to be involved in the pathophysiology of various ocular diseases in the anterior and posterior segment of the eye. In this review, we aim to summarize the mechanisms of oxidative stress in ocular diseases to provide an updated understanding on the pathogenesis of common diseases affecting the ocular surface, the lens, the retina, and the optic nerve. Moreover, we discuss potential therapeutic approaches aimed at reducing oxidative stress in this context.

The ideal treatment timing for diabetic retinopathy: the molecular pathological mechanisms underlying early-stage diabetic retinopathy are a matter of concern

Diabetic retinopathy (DR) is a prevalent complication of diabetes, significantly impacting patients' quality of life due to vision loss. No pharmacological therapies are currently approved for DR, excepted the drugs to treat diabetic macular edema such as the anti-VEGF agents or steroids administered by intraocular route. Advancements in research have highlighted the crucial role of early intervention in DR for halting or delaying disease progression. This holds immense significance in enhancing patients' quality of life and alleviating the societal burden associated with medical care costs. The non-proliferative stage represents the early phase of DR. In comparison to the proliferative stage, pathological changes primarily manifest as microangiomas and hemorrhages, while at the cellular level, there is a loss of pericytes, neuronal cell death, and disruption of components and functionality within the retinal neuronal vascular unit encompassing pericytes and neurons. Both neurodegenerative and microvascular abnormalities manifest in the early stages of DR. Therefore, our focus lies on the non-proliferative stage of DR and we have initially summarized the mechanisms involved in its development, including pathways such as polyols, that revolve around the pathological changes occurring during this early stage. We also integrate cutting-edge mechanisms, including leukocyte adhesion, neutrophil extracellular traps, multiple RNA regulation, microorganisms, cell death (ferroptosis and pyroptosis), and other related mechanisms. The current status of drug therapy for early-stage DR is also discussed to provide insights for the development of pharmaceutical interventions targeting the early treatment of DR.

GRg1 inhibits the TLR4/NF-kB signaling pathway by upregulating miR-216a-5p to reduce growth factors and inflammatory cytokines in DR

BACKGROUND

Diabetic retinopathy (DR) is a common diabetic neurodegenerative disease that affects vision in severe cases. Current therapeutic drugs are ineffective for some patients with severe side effects, and ginsenoside-Rg1 (GRg1) has been shown to protect against DR and may serve as a new potential drug for DR. This study aimed to confirm the protective effect of GRg1 against DR and its molecular mechanism.

METHODS

Human retinal microvascular endothelial cells (hRMECs) and rats were used to construct DR models in vitro and in vivo. Cell proliferation was detected by BrdU assays, the cell cycle was detected by flow cytometry, and TNF-α, IL-6 and IL-1β levels were detected by ELISA. qRT‒PCR, Western blotting and immunohistochemistry were used to detect the expression of related genes and proteins, and angiogenesis assays were used to assess angiogenesis. RIP and RNA pull down assays were used to determine the relationship between miR-216a-5p and TLR4; retinal structure and changes were observed by HE staining and retinal digestive spread assays.

RESULTS

GRg1 effectively inhibited HG-induced hRMEC proliferation, cell cycle progression and angiogenesis and reduced the levels of intracellular inflammatory cytokines and growth factors. HG downregulated the expression of miR-216a-5p and upregulated the expression of TLR4/NF-kB signaling pathway-related proteins. Importantly, GRg1 inhibited TLR4/NF-kB signaling pathway activation by upregulating miR-216a-5p, thereby inhibiting HG-induced cell proliferation, cell cycle progression, angiogenesis, and the production of inflammatory cytokines and growth factors. In addition, animal experiments confirmed the results of the cell experiments.

CONCLUSIONS

GRg1 inhibits TLR4/NF-kB signaling by upregulating miR-216a-5p to reduce growth factors and inflammatory cytokines in DR, providing a potential therapeutic strategy for DR.

Vascular complications of diabetes: A narrative review

Diabetes mellitus is a complex chronic metabolic disease characterized by hyperglycemia and various complications. According to the different pathophysiological mechanisms, these complications can be classified as microvascular or macrovascular complications, which have long-term negative effects on vital organs such as the eyes, kidneys, heart, and brain, and lead to increased patient mortality. Diabetes mellitus is a major global health issue, and its incidence and prevalence have increased significantly in recent years. Moreover, the incidence is expected to continue to rise as more people adopt a Western lifestyle and diet. Thus, it is essential to understand the epidemiology, pathogenesis, risk factors, and treatment of vascular complications to aid patients in managing the disease effectively. This paper provides a comprehensive review of the literature to clarify the above content. Furthermore, this paper also delves into the correlation between novel risk factors, such as long noncoding RNAs, gut microbiota, and nonalcoholic fatty liver disease, with diabetic vascular complications.

Hu-Zhang Qing-Mai Formulation anti-oxidative stress alleviates diabetic retinopathy: Network pharmacology analysis and in vitro experiment

BACKGROUND

In this study, the potential mechanism of the Hu-Zhang Qing-Mai Formulation (HZQMF) on diabetic retinopathy (DR) in inhibiting oxidative stress was explored through network pharmacology analysis and in vitro experiments.

METHODS

The Traditional Chinese Medicine Systematic Pharmacology Analysis Platform was used to retrieve the active pharmaceutical ingredients and targets of HZQMF. DR-related genes and oxidative stress-related genes were obtained from PharmGKB, TTD, OMIM, GeneCards, and Drugbank. STRING was used to construct a protein-protein interaction network to screen core targets. Gene ontology and Kyoto encyclopedia of genes and genomes enrichment analyses were performed using R 4.0.3. Network topology analysis was carried out using Cytoscape 3.8.2. Finally, we looked into how well the main API protected human retinal pigment epithelial cells from damage brought on by hydrogen peroxide (H2O2).

RESULTS

Quercetin (Que) was identified as the primary API of HZQMF through network pharmacology analysis, while JUN, MAPK1, and STAT3 were identified as the primary hub genes. Kyoto encyclopedia of genes and genomes enrichment analysis showed that the AGE-RAGE signaling pathway may be crucial to the therapeutic process. In vitro experiments confirmed that Que increased cell vitality and inhibited apoptosis.

CONCLUSION

Que might significantly reduce H2O2-induced ARPE-19 cell injury by inhibiting apoptosis-related genes of the AGE-RAGE pathway (JUN, MAPK1, STAT3). This study lays the foundation for further research on HZQMF in treating DR.

Exosome-based drug delivery systems for the treatment of diabetes and its complications: current opinion

Diabetes medication is based on controlling blood glucose and delaying the onset of related complications and is not a complete cure for diabetes. Conventional drug therapy fails to stop progressive islet β cell failure in diabetic patients. Recent studies have shown that "exosome-based therapy" holds great promise in treating diabetes and its complications. Exosomes are small vesicles that are stable in the bloodstream and can effectively deliver therapeutic drugs to specific tissues or organs through intercellular communication. Using exosomes as carriers for drug delivery offers several advantages. This review summarizes the benefits of exosomal drug delivery systems, drug loading methods, and their applications in treating diabetes and its complications. However, there are still challenges to overcome in using exosomal drug delivery systems, such as large-scale production, assessing the contents of exosomes, and monitoring the safety and effectiveness of the treatment in vivo. In conclusion, this review proposes the therapeutical potential of exosomes as drug carriers for developing novel drugs to provide new strategies for treating diabetes and its complications.

Effects of amygdalin on ferroptosis and oxidative stress in diabetic retinopathy progression via the NRF2/ARE signaling pathway

Oxidative stress has been involved in the pathogenesis of diabetic retinopathy (DR). Amygdalin is an effective component of bitter almond that exhibits excellent antioxidant properties. We explored the effects of amygdalin on ferroptosis and oxidative stress in high-glucose (HG)-stimulated human retinal endothelial cells (HRECs) via the NRF2/ARE pathway. HG-stimulated HRECs were used to establish a DR model. Cell viability was evaluated using the MTT assay. The release of lactate dehydrogenase was used to evaluate cell toxicity. The protein levels of NRF2, NQO1, and HO-1 were detected using western blotting. The GSH, GSSG, GPX4, SOD, CAT, MDA, and Fe2+ levels in the HRECs were also detected. Flow cytometry was used to detect reactive oxygen species (ROS) using a fluorescent probe. Immunofluorescence staining was performed to detect NRF2 expression. The results revealed that HG stimulation decreased the levels of GSH, GPX4, SOD, and CAT but increased those of MDA, ROS, GSSG, and Fe2+ in HRECs. Ferrostatin-1 treatment reversed the effects of HG stimulation, whereas erastin aggravated these effects. Amygdalin treatment relieved HG-induced injury in HRECs. Amygdalin treatment promoted the nuclear transport of NRF2 in HG-stimulated HRECs. NQO1 and HO-1 levels were upregulated in HG-stimulated HRECs after amygdalin treatment. An inhibitor of NRF2 reversed the effects of amygdalin. Therefore, amygdalin treatment inhibited ferroptosis and oxidative stress in HG-stimulated HRECs by activating the NRF2/ARE signaling pathway.

The association between circulatory, local pancreatic PCSK9 and type 2 diabetes mellitus: The effects of antidiabetic drugs on PCSK9

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a potent modulator of cholesterol metabolism and plays a crucial role in the normal functioning of pancreatic islets and the progression of diabetes. Islet autocrine PCSK9 deficiency can lead to the enrichment of low-density lipoprotein (LDL) receptor (LDLR) and excessive LDL cholesterol (LDL-C) uptake, subsequently impairing the insulin secretion in β-cells. Circulatory PCSK9 levels are primarily attributed to hepatocyte secretion. Notably, anti-PCSK9 strategies proposed for individuals with hypercholesterolemia chiefly target liver-derived PCSK9; however, these anti-PCSK9 strategies have been associated with the risk of new-onset diabetes mellitus (NODM). In the current review, we highlight a new direction in PCSK9 inhibition therapy strategies: screening candidates for anti-PCSK9 from the drugs used in type 2 diabetes mellitus (T2DM) treatment. We explored the association between circulating, local pancreatic PCSK9 and T2DM, as well as the relationship between PCSK9 monoclonal antibodies and NODM. We discussed the emergence of artificial and natural drugs in recent years, exhibiting dual benefits of antidiabetic activity and PCSK9 reduction, confirming that the diverse effects of these drugs may potentially impact the progression of diabetes and associated disorders, thereby introducing novel avenues and methodologies to enhance disease prognosis.