New Diagnostic and Therapeutic Approaches for Preventing the Progression of Diabetic Retinopathy

Nimbolide: promising agent for prevention and treatment of chronic diseases (recent update)

Background

Nimbolide, a bioactive compound derived from the neem tree, has garnered attention as a potential breakthrough in the prevention and treatment of chronic diseases. Recent updates in research highlight its multifaceted pharmacological properties, demonstrating anti-inflammatory, antioxidant, and anticancer effects. With a rich history in traditional medicine, nimbolide efficacy in addressing the molecular complexities of conditions such as cardiovascular diseases, diabetes, and cancer positions it as a promising candidate for further exploration. As studies progress, the recent update underscores the growing optimism surrounding nimbolide as a valuable tool in the ongoing pursuit of innovative therapeutic strategies for chronic diseases.

Methods

The comprehensive search of the literature was done until September 2020 on the MEDLINE, Embase, Scopus and Web of Knowledge databases.

Results

Most studies have shown the Nimbolide is one of the most potent limonoids derived from the flowers and leaves of neem (Azadirachta indica), which is widely used to treat a variety of human diseases. In chronic diseases, nimbolide reported to modulate the key signaling pathways, such as Mitogen-activated protein kinases (MAPKs), Wingless-related integration site-β (Wnt-β)/catenin, NF-κB, PI3K/AKT, and signaling molecules, such as transforming growth factor (TGF-β), Matrix metalloproteinases (MMPs), Vascular Endothelial Growth Factor (VEGF), inflammatory cytokines, and epithelial-mesenchymal transition (EMT) proteins. Nimbolide has anti-inflammatory, anti-microbial, and anti-cancer properties, which make it an intriguing compound for research. Nimbolide demonstrated therapeutic potential for osteoarthritis, rheumatoid arthritis, cardiovascular, inflammation and cancer.

Conclusion

The current review mainly focused on understanding the molecular mechanisms underlying the therapecutic effects of nimbolide in chronic diseases.

Lens epithelial cell-derived exosome inhibits angiogenesis in ocular pathological neovascularization through its delivery of miR-146a-5p

Abnormal ocular neovascularization, a major pathology of eye diseases, leads to severe visual loss. The role of lens epithelial cell (LEC)-derived exosomes (Lec-exo) is largely unknown. Thus, we aimed to investigate whether Lec-exo can inhibit abnormal ocular neovascularization and explore the possible mechanisms. In our study, we proved the first evidence that exosomes derived from LECs attenuated angiogenesis in both oxygen-induced retinopathy and laser-induced choroidal neovascularization mice models. Further in vitro experiments proved that Lec-exo inhibited proliferation, migration, and tube formation capability of human umbilical vein endothelial cells in high glucose condition. Further high-throughput miRNAs sequencing analysis detected that miR-146a-5p was enriched in Lec-exo. Mechanistically, exosomal miR-146a-5p was delivered to endothelial cells and bound to the NRAS coding sequence, which subsequently inactivated AKT/ERK signaling pathway. We successfully elucidated the function of Lec-exo in inhibiting abnormal ocular neovascularization, which may offer a promising strategy for treatment of abnormal ocular neovascularization.

Therapeutic effects of herbal medicines in different types of retinopathies: A systematic review

Objective

Retinopathy is an ocular manifestation of systemic diseases such as diabetes and vascular diseases. Herbal drugs have been considered as an effective therapeutic option with minimal side effects for the treatment of retinopathy by reducing the symptoms and improving visual acuity. The purpose of this systematic review was to collect studies on the effectiveness of medicinal plants in the treatment or prevention of retinopathy.

Materials and Methods

A systematic literature search was performed in PubMed, Scopus, Google Scholar, and other databases in April 2021 using "herbal products" and "Retinopathy" with all their equivalent and similar terms. For this purpose, human clinical trials with the English language were included and articles with subject irrelevancy were excluded from further evaluation.

Results

Overall, 30 articles with 2324 patients were studied for possible effects of herbal therapy on retinopathy. From 30 included articles, different herbal products had been evaluated. Out of 30 selected articles, 11 articles were for the treatment of age-related macular degeneration (AMD), 14 articles covered patients with diabetic retinopathy, and the other five studies were for other retinal disorders. The outcomes in majority of the studies include changes in visual acuity (VA), fundus performance, best-corrected visual acuity (BCVA), central macular thickness (CMT), focal electroretinogram (fERG), supplements and adjuvant medications appeared to be more beneficial in patients with AMD and diabetic maculopathy.

Conclusion

Herbal therapy can be considered as a potential candidate in the adjuvant and complementary therapies of retinopathy. However, further studies are required to verify such efficiency.

Exploring various novel diagnostic and therapeutic approaches in treating diabetic retinopathy

Diabetic retinopathy is regarded as a common manifestation of diabetes mellitus, being a prominent cause of visual impairment and blindness. This microvascular complication is marked by the appearance of microaneurysms, elevated vascular permeability, capillary blockage, and proliferation of neovasculature. The etiology behind retinopathy is ambiguous and the efficacy of current treatment strategies is minimal. Early diagnosis of this complication using a biomarker with high sensitivity and specificity is very essential for providing better therapeutic strategies. The current available therapeutic options are limited with various adverse effects. Laser treatment is not beneficial in all the situations, economic constraints being the major challenge. Surgical interventions are employed when pharmacotherapy and laser treatment fail. New pharmacological treatments are becoming a necessity for treating the condition. This review highlights the use of various diagnostic tools, emerging biomarkers for early detection of diabetic retinopathy, pathological mechanisms associated with the disease, current therapeutic approaches used and future strategies for more enhanced treatment options and more potent pharmacological actions.

Role of acyl-coenzyme A: cholesterol transferase 1 (ACAT1) in retinal neovascularization

BACKGROUND

We have investigated the efficacy of a new strategy to limit pathological retinal neovascularization (RNV) during ischemic retinopathy by targeting the cholesterol metabolizing enzyme acyl-coenzyme A: cholesterol transferase 1 (ACAT1). Dyslipidemia and cholesterol accumulation have been strongly implicated in promoting subretinal NV. However, little is known about the role of cholesterol metabolism in RNV. Here, we tested the effects of inhibiting ACAT1 on pathological RNV in the mouse model of oxygen-induced retinopathy (OIR).

METHODS

In vivo studies used knockout mice that lack the receptor for LDL cholesterol (LDLR^-/-) and wild-type mice. The wild-type mice were treated with a specific inhibitor of ACAT1, K604 (10 mg/kg, i.p) or vehicle (PBS) during OIR. In vitro studies used human microglia exposed to oxygen-glucose deprivation (OGD) and treated with the ACAT1 inhibitor (1 μM) or PBS.

RESULTS

Analysis of OIR retinas showed that increased expression of inflammatory mediators and pathological RNV were associated with significant increases in expression of the LDLR, increased accumulation of neutral lipids, and formation of toxic levels of cholesterol ester (CE). Deletion of the LDLR completely blocked OIR-induced RNV and significantly reduced the AVA. The OIR-induced increase in CE formation was accompanied by significant increases in expression of ACAT1, VEGF and inflammatory factors (TREM1 and MCSF) (p < 0.05). ACAT1 was co-localized with TREM1, MCSF, and macrophage/microglia makers (F4/80 and Iba1) in areas of RNV. Treatment with K604 prevented retinal accumulation of neutral lipids and CE formation, inhibited RNV, and decreased the AVA as compared to controls (p < 0.05). The treatment also blocked upregulation of LDLR, ACAT1, TREM1, MCSF, and inflammatory cytokines but did not alter VEGF expression. K604 treatment of microglia cells also blocked the effects of OGD in increasing expression of ACAT1, TREM1, and MCSF without altering VEGF expression.

CONCLUSIONS

OIR-induced RNV is closely associated with increases in lipid accumulation and CE formation along with increased expression of LDLR, ACAT1, TREM1, and MCSF. Inhibiting ACAT1 blocked these effects and limited RNV independently of alterations in VEGF expression. This pathway offers a novel strategy to limit vascular injury during ischemic retinopathy.

Diabetic Retinopathy Detection from Fundus Images of the Eye Using Hybrid Deep Learning Features

Diabetic Retinopathy (DR) is a medical condition present in patients suffering from long-term diabetes. If a diagnosis is not carried out at an early stage, it can lead to vision impairment. High blood sugar in diabetic patients is the main source of DR. This affects the blood vessels within the retina. Manual detection of DR is a difficult task since it can affect the retina, causing structural changes such as Microaneurysms (MAs), Exudates (EXs), Hemorrhages (HMs), and extra blood vessel growth. In this work, a hybrid technique for the detection and classification of Diabetic Retinopathy in fundus images of the eye is proposed. Transfer learning (TL) is used on pre-trained Convolutional Neural Network (CNN) models to extract features that are combined to generate a hybrid feature vector. This feature vector is passed on to various classifiers for binary and multiclass classification of fundus images. System performance is measured using various metrics and results are compared with recent approaches for DR detection. The proposed method provides significant performance improvement in DR detection for fundus images. For binary classification, the proposed modified method achieved the highest accuracy of 97.8% and 89.29% for multiclass classification.

Nimbolide ameliorates the streptozotocin-induced diabetic retinopathy in rats through the inhibition of TLR4/NF-κB signaling pathway

BACKGROUND

Diabetic retinopathy (DR) is a common problem in the diabetic patients due to the high blood glucose level. DR affects more number of diabetic patients worldwide with irreversible vision loss.

OBJECTIVE

The current investigation was focused to reveal the therapeutic actions of nimbolide against the streptozotocin (STZ)-provoked DR in rats through inhibition of TLR4/NF-κB pathway.

METHODOLOGY

DR was provoked to the rats through administering a single dose of STZ (60 mg/kg) intraperitoneally. The DR rats were then supplemented with the 50 mg/kg of nimbolide for 60 days. The bodyweight and blood glucose level was measured using standard methods. The lipid profiles (cholesterol, TG, LDL, and HDL), inflammatory markers, and antioxidants level was detected using respective kits. The level of MCP-1, VEGF, and MMP-9 was quantified using kits. The morphometric analysis of retinal tissues were done. The mRNA expressions of target genes were studied using RT-PCR assay.

RESULTS

Nimbolide treatment effective decreased the food intake and blood glucose, and improved the bodyweight of STZ-provoked animals. The levels of pro-inflammatory mediators, cholesterol, TG, LDL, and HDL, MCP-1, VEGF, and MMP-9 was remarkably suppressed by the nimbolide treatment. Nimbolide also improved the antioxidants, retinal thickness and cell numbers. The TLR4/NF-κB pathway was appreciably inhibited by the nimbolide.

CONCLUSION

Overall, our findings demonstrated that the nimbolide attenuated the STZ-provoked DR in rats through inhibiting the TLR4/NF-κB pathway.

Diabetic retinopathy detection through convolutional neural networks with synaptic metaplasticity

BACKGROUND AND OBJECTIVES

Diabetic retinopathy is a type of diabetes that causes vascular changes that can lead to blindness. The ravages of this disease cannot be reversed, so early detection is essential. This work presents an automated method for early detection of this disease using fundus colored images.

METHODS

A bio-inspired approach is proposed on synaptic metaplasticity in convolutional neural networks. This biological phenomenon is known to directly interfere in both learning and memory by reinforcing less common occurrences during the learning process. Synaptic metaplasticity has been included in the backpropagation stage of a convolution operation for every convolutional layer.

RESULTS

The proposed method has been evaluated by using a public small diabetic retinopathy dataset from Kaggle with four award-winning convolutional neural network architectures. Results show that convolutional neural network architectures including synaptic metaplasticity improve both learning rate and accuracy. Furthermore, obtained results outperform other methods in current literature, even using smaller datasets for training. Best results have been obtained for the InceptionV3 architecture with synaptic metaplasticity with a 95.56% accuracy, 94.24% F1-score, 98.9% precision and 90% recall, using 3662 images for training.

CONCLUSIONS

Convolutional neural networks with synaptic metaplasticity are suitable for early detection of diabetic retinopathy due to their fast convergence rate, training simplicity and high performance.

A Real-World Single-Centre Study of Patients with Diabetic Macular Oedema Who Wore a Home-Use Sleep Mask (Noctura 400) for One Year

A “Real-World” single-centre observational study was carried out to analyse the effects of enhanced patient interaction with the use of the Noctura 400 sleep mask on a group of 26 diabetics displaying diabetic retinopathy (DR) and diabetic macular oedema (DMO), of which 24 completed the study. We hoped to find if patient compliance could be maintained and to determine the anatomical and functional consequences of consistent mask wear. While this study was ongoing, COVID-19 impacted on normal eye clinic practice, allowing an unexpected analysis of the effects of this disruption to the clinical system on mask wear and disease progress. Throughout the whole study, outcomes were positive, with a high level of consistent patient use of the mask, above 74% up to and beyond 1 year. Even during the COVID-19 1st lockdown in England, the patients maintained a 65% nightly light mask compliance. Statistically significant improvements in maculopathy, including cyst reduction (56.4% of eyes with cysts exhibited cyst shrinkage), and visual acuity (VA) improvement (42/48 eyes gained 5 letters or more) were observed and maintained to the end of the study. Anatomical improvement or stability was recorded in all but one study eye. This investigation shows that given that there is appropriate interaction with patients who are self-treating in home environment, a high level of patient compliance can be maintained, even while there are disruptions to the normal hospital clinic setup.

Blocking the interaction between interleukin-17A and endoplasmic reticulum stress in macrophage attenuates retinal neovascularization in oxygen-induced retinopathy

BACKGROUND

Neovascularization is a leading cause of visual loss typically associated with diabetic retinopathy (DR) and retinopathy of prematurity (ROP). Interleukin-17A (IL-17A) and endoplasmic reticulum (ER) stress both have been demonstrated to play a proangiogenic role in ischemic retinopathies. However, the relationship between IL-17A and ER stress in retinal neovascularization (RNV) under hypoxic conditions and its underlying mechanisms remain unclear.

METHODS

In this study, oxygen-induced retinopathy (OIR) mice model was established and intravitreal injections were conducted. Changes of IL-17A and ER stress markers in retinas and cultured primary bone marrow derived macrophage (BMDM) under normoxic or hypoxic conditions were detected. Western blotting, Real-Time RT-PCR, Immunofluorescence assays were conducted to explore the roles and relationship of IL-17A and ER stress in RNV, as well as its underlying mechanisms.

RESULTS

Compared to that in normal controls, IL-17A and ER stress markers were all remarkably increased under hypoxic conditions both in vivo and in vitro. Neutralization or knock out of IL-17A decreased ER stress. ER stress inhibitor 4-phenylbutyrate (4-PBA), attenuated the production of IL-17A, suggesting a positive feedback loop between IL-17A and ER stress. Inhibition of IL-17A or ER stress decreased areas of nonperfusion and neovascularization in OIR retinas. As TXNIP/NLRP3 pathway activation has been demonstrated to be involved in increased retinal vascular permeability of ischemic retinopathy, we observed that TXNIP/NLRP3 pathway mediated in the interaction between IL-17A and ER stress under hypoxic conditions.

CONCLUSION

The interplay between IL-17A and ER stress contributes to RNV in macrophages via modulation of TXNIP/NLRP3 signaling pathway under hypoxic conditions. The feedback loops may become an innovative and multiple pharmacological therapeutic target for ischemic retinopathy.

Efficacy of intravitreal injection of conbercept on non-proliferative diabetic retinopathy: a retrospective study

Objective

This study assessed the efficacy of conbercept for patients with non-proliferative diabetic retinopathy (NPDR).

Methods

In this retrospective clinical study, 54 patients with NPDR (54 eyes) were treated with intravitreal injection of conbercept using a 3+ pro re nata regimen and followed up for 12 months. Best corrected visual acuity (BCVA), central foveal thickness (CFT), area of hard exudate (HE), and number of microaneurysms (MAs) were used as indicators of therapeutic effects. Systemic adverse reactions were recorded to assess safety.

Results

During the 12-month follow-up period, the mean number of injections was 6.12 ± 1.89 on demand. From baseline to the 12-month follow-up, the BCVA of patients with NPDR increased from 0.71 ± 0.20 logMAR to 0.43 ± 0.16 logMAR, CFT decreased from 424.26 ± 64.89 μm to 269.27 ± 44.79 μm, and the number of MAs declined from 79.53 ± 27.18 to 33.34 ± 16.53. Moreover, the area of HE was significantly reduced after 9 months of treatment. There were no serious systemic adverse events during the follow-up.

Conclusions

Intravitreal injection of conbercept has a stable and robust effect on patients with NPDR over a 12-month follow-up period. Thus, conbercept is an effective and feasible treatment for NPDR.

An evidence map of clinical practice guideline recommendations and quality on diabetic retinopathy

To present an evidence map for explicating research trends and gaps, we systematically review clinical practice guidelines (CPGs) on diabetic retinopathy (DR) and assess the quality of CPGs and consistency of recommendations. A literature search was performed in PubMed, Embase, Web of Science, CPG databases, and website of diabetes society to include the CPGs. The basic information, methodological quality, and reporting quality of CPGs, recommendations for DR were exacted by the Excel 2013. Methodological and reporting quality of DR CPGs were evaluated by AGREE II instrument and RIGHT checklist. The bubble plot format of evidence map was made by Excel 2013. Nineteen CPGs proved eligible, which included eight DR CPGs and 11 comprehensive diabetic CPGs. The identified CPGs were of mixed quality and they scored poorly in the rigor of development, applicability domains by AGREE II. Field two (background) had the highest reporting rate (86.31%) and field five (review and quality assurance) obtained the lowest reporting rate (31.58%) among the seven domains of RIGHT checklist. According to the recommendations of CPGs, there were three inconsistencies in the screening of DR, and CPGs recommendations for treatment were consistent on the whole. At the same time, recommendations for laser therapy were not accurate. Some recommendations were not specific and clear in some DR CPGs. This evidence map could collect and evaluate the characteristics of published CPGs, add to our knowledge and promote the development of trustworthy CPGs for DR.

Trace Biomolecule Detection with Functionalized Janus Particles by Rotational Diffusion

Cytokines are small proteins secreted by cells in innate and adaptive immune systems. Abnormal cytokine secretion is often regarded as an early cue of dysregulation of homeostasis due to diseases or infections. Early detection allows early medical intervention. In this study, a natural phenomenon called rotational Brownian motion was characterized by Janus particles and its potential use in detection of trace biomolecules explored. Through the functionalization of the Janus particles with an antibody, the target cytokine, that is, tumor necrosis factor-α, was measured in terms of rotational diffusion. Rotational diffusion is highly sensitive to the particle volume change according to the Stokes-Einstein-Debye relation and can be quantified by blinking signal. Accordingly, 1 μm half-gold and half-fluorescent microbeads were conjugated with 200 nm nanobeads through sandwiched immunocomplexes. The light source, lead time for stabilization, and purification were investigated for optimization. Particle images can be captured with green light at 5 Hz within 300 s. Under such conditions, the functionalized Janus particles eventually achieved a limit of detection of 1 pg/mL. The rotational diffusometry realized by Janus particles was power-free and feasible for ultrasensitive detection, such as early disease detection.

Deep learning algorithms for detection of diabetic retinopathy in retinal fundus photographs: A systematic review and meta-analysis

BACKGROUND

Diabetic retinopathy (DR) is one of the leading causes of blindness globally. Earlier detection and timely treatment of DR are desirable to reduce the incidence and progression of vision loss. Currently, deep learning (DL) approaches have offered better performance in detecting DR from retinal fundus images. We, therefore, performed a systematic review with a meta-analysis of relevant studies to quantify the performance of DL algorithms for detecting DR.

METHODS

A systematic literature search on EMBASE, PubMed, Google Scholar, Scopus was performed between January 1, 2000, and March 31, 2019. The search strategy was based on the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guidelines, and DL-based study design was mandatory for articles inclusion. Two independent authors screened abstracts and titles against inclusion and exclusion criteria. Data were extracted by two authors independently using a standard form and the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool was used for the risk of bias and applicability assessment.

RESULTS

Twenty-three studies were included in the systematic review; 20 studies met inclusion criteria for the meta-analysis. The pooled area under the receiving operating curve (AUROC) of DR was 0.97 (95%CI: 0.95-0.98), sensitivity was 0.83 (95%CI: 0.83-0.83), and specificity was 0.92 (95%CI: 0.92-0.92). The positive- and negative-likelihood ratio were 14.11 (95%CI: 9.91-20.07), and 0.10 (95%CI: 0.07-0.16), respectively. Moreover, the diagnostic odds ratio for DL models was 136.83 (95%CI: 79.03-236.93). All the studies provided a DR-grading scale, a human grader (e.g. trained caregivers, ophthalmologists) as a reference standard.

CONCLUSION

The findings of our study showed that DL algorithms had high sensitivity and specificity for detecting referable DR from retinal fundus photographs. Applying a DL-based automated tool of assessing DR from color fundus images could provide an alternative solution to reduce misdiagnosis and improve workflow. A DL-based automated tool offers substantial benefits to reduce screening costs, accessibility to healthcare and ameliorate earlier treatments.

Novel Cell-Based and Tissue Engineering Approaches for Induction of Angiogenesis as an Alternative Therapy for Diabetic Retinopathy

Diabetic retinopathy (DR) is the most frequent microvascular complication of long-term diabetes and the most common cause of blindness, increasing morbidity in the working-age population. The most effective therapies for these complications include laser photocoagulation and anti-vascular endothelial growth factor (VEGF) intravitreal injections. However, laser and anti-VEGF drugs are untenable as a final solution as they fail to address the underlying neurovascular degeneration and ischemia. Regenerative medicine may be a more promising approach, aimed at the repair of blood vessels and reversal of retinal ischemia. Stem cell therapy has introduced a novel way to reverse the underlying ischemia present in microvascular complications in diseases such as diabetes. The present review discusses current treatments, their side effects, and novel cell-based and tissue engineering approaches as a potential alternative therapeutic approach.

Vascular Regeneration for Ischemic Retinopathies: Hope from Cell Therapies

Retinal vascular diseases, such as diabetic retinopathy, retinopathy of prematurity, retinal vein occlusion, ocular ischemic syndrome and ischemic optic neuropathy, are leading causes of vision impairment and blindness. Whilst drug, laser or surgery-based treatments for the late stage complications of many of these diseases are available, interventions that target the early vasodegenerative stages are lacking. Progressive vasculopathy and ensuing ischemia is an underpinning pathology in many of these diseases, leading to hypoperfusion, hypoxia, and ultimately pathological neovascularization and/or edema in the retina and other ocular tissues, such as the optic nerve and iris. Therefore, repairing the retinal vasculature may prevent progression of ischemic retinopathies into late stage vascular complications. Various cell types have been explored for their vascular repair potential. Endothelial progenitor cells, mesenchymal stem cells and induced pluripotent stem cells are studied for their potential to integrate with the damaged retinal vasculature and limit ischemic injury. Clinical trials for some of these cell types have confirmed safety and feasibility in the treatment of ischemic diseases, including some retinopathies. Another promising avenue is mobilization of endogenous endothelial progenitors, whereby reparative cells are moved from their niche to circulating blood to target and home into ischemic tissues. Several aspects and properties of these cell types have yet to be elucidated. Nevertheless, we foresee that cell therapy, whether through delivery of exogenous or enhancement of endogenous reparative cells, will become a valuable and beneficial treatment for ischemic retinopathies.

Elevated serum OxLDL is associated with progression of type 2 Diabetes Mellitus to diabetic retinopathy

Hyperlipidemia is associated with the progression of diabetic retinopathy (DR). Paraoxonase 1 (PON1), an esterase is known to prevent systemic LDL oxidation. This study assessed if serum oxLDL is associated with the progression of Type 2 DM to DR. This study is part of a three-year hospital based prospective study where 87 subjects were recruited. This included T2DM without DR (n = 22); Non-Proliferative (NPDR) (n = 21) and Proliferative DR (PDR) (n = 22) along with age/sex matched controls (n = 22). Serum oxLDL-Ab was estimated by ELISA. Serum PON esterase activity and plasma Malondialdehyde (MDA) level were estimated by spectrophotometry and the serum Advanced Glycation End products (AGE) level by spectroflourimetry. The systemic levels of oxLDL, AGE and MDA were increased with the progression of T2DM without DR to DR as seen by ANOVA (P < 0.05). Serum oxLDL-Ab levels showed a positive correlation to total cholesterol (P = 0.04) as evaluated in the DR group. Statin intake was found to lower PON esterase activity (P < 0.05). Based on this pilot study, it is proposed that elevated serum oxLDL should be validated in larger cohort studies to ensure it could be potential risk factor for the progression of T2DM to DR.

Apocynin ameliorates diabetic retinopathy in rats: Involvement of TLR4/NF-κB signaling pathway

Diabetic retinopathy is a diabetes complication. During diabetic retinopathy development, the TLR4/NF-κB pathway is up-regulated. Apocynin is a nicotinamide adenine dinucleotide phosphate oxidase blocker which can reduce the superoxide radicals. It is demonstrated that apocynin can inhibit TLR4/NF-κB pathway in rats. We aim to figure out whether apocynin treatment is benefit for the diabetic retinopathy in rat model. The diabetes in rats was induced by streptozotocin. The treatment of apocynin (16 mg/kg/day) or vehicle in diabetic rat model was maintained for 12 weeks. The expression levels of relative genes in this research were shown through Western blot and qRT-PCR. Morphology of the retinas was shown by Hematoxylin-Eosin staining. The treatment of apocynin ameliorated biochemical indexes in diabetic rats and rescued the morphology of the retinas. After a 12 weeks apocynin treatment, the cell apoptosis, oxidative stress, and inflammatory in retina was reduced in diabetic rats. TLR4/NF-κB signaling pathway activity in diabetic rat retina was inhibited by apocynin. Based on our study, the treatment of apocynin ameliorates diabetic retinopathy in rats. The TLR4/NF-κB signaling pathway inhibition by apocynin is involved in this process. This result indicated a great therapeutic potential of apocynin in diabetic retinopathy treatment.

Prevalence and association of clinical characteristics and biochemical factors with complications of diabetes mellitus in Palestinians treated in primary healthcare practice

AIMS

The current study was carried out to examine prevalence of complications related to diabetes mellitus (DM) and to investigate association between clinical variables and biochemical factors with complications of DM in patients treated in primary healthcare settings in the West Bank of Palestine.

MATERIALS AND METHODS

Sociodemographic, clinical, and biochemical variables were collected from 385 patients visiting 17 primary healthcare settings in the West Bank. Patients provided blood and urine samples, responded to a questionnaire interview, and were subjected to ophthalmic examination.

RESULTS

HbA_1c levels were predicted by duration of DM (p < 0.001), HDL (p = 0.011), alkaline phosphatase (p = 0.001), blood urea (p = 0.006), and LDL (p = 0.008). Triglycerides levels were predicted by blood urea (p = 0.002), HDL (p < 0.001), and total cholesterol (p < 0.001). GOT levels were predicted by LDL (p = 0.002) and GPT (p < 0.001). GPT levels were predicted by HDL (p = 0.003) and blood urea (p = 0.025). Urine albumin were predicted by total cholesterol (p = 0.001), LDL (p = 0.005), and blood urea (p = 0.036). CD ratio was predicted by the IOP and the IOP was predicted by the CD ratio (p = 0.001).

CONCLUSIONS

Prevalence of complications related to DM was high among patients with DM treated in primary healthcare practice. These complications and risk factors were predicted by certain clinical characteristics and biochemical factors. Policies and programs are needed to manage these modifiable risk factors.

Bone Marrow CD133+ Stem Cells Ameliorate Visual Dysfunction in Streptozotocin-induced Diabetic Mice with Early Diabetic Retinopathy

Diabetic retinopathy (DR), one of the leading causes of vision loss worldwide, is characterized by neurovascular disorders. Emerging evidence has demonstrated retinal neurodegeneration in the early pathogenesis of DR, and no treatment has been developed to prevent the early neurodegenerative changes that precede detectable microvascular disorders. Bone marrow CD133+ stem cells with revascularization properties exhibit neuroregenerative potential. However, whether CD133+ cells can ameliorate the neurodegeneration at the early stage of DR remains unclear. In this study, mouse bone marrow CD133+ stem cells were immunomagnetically isolated and analyzed for the phenotypic characteristics, capacity for neural differentiation, and gene expression of neurotrophic factors. After being labeled with enhanced green fluorescent protein, CD133+ cells were intravitreally transplanted into streptozotocin (STZ)-induced diabetic mice to assess the outcomes of visual function and retina structure and the mechanism underlying the therapeutic effect. We found that CD133+ cells co-expressed typical hematopoietic/endothelial stem/progenitor phenotypes, could differentiate to neural lineage cells, and expressed genes of robust neurotrophic factors in vitro. Functional analysis demonstrated that the transplantation of CD133+ cells prevented visual dysfunction for 56 days. Histological analysis confirmed such a functional improvement and showed that transplanted CD133+ cells survived, migrated into the inner retina (IR) over time and preserved IR degeneration, including retina ganglion cells (RGCs) and rod-on bipolar cells. In addition, a subset of transplanted CD133+ cells in the ganglion cell layer differentiated to express RGC markers in STZ-induced diabetic retina. Moreover, transplanted CD133+ cells expressed brain-derived neurotrophic factors (BDNFs) in vivo and increased the BDNF level in STZ-induced diabetic retina to support the survival of retinal cells. Based on these findings, we suggest that transplantation of bone marrow CD133+ stem cells represents a novel approach to ameliorate visual dysfunction and the underlying IR neurodegeneration at the early stage of DR.

Clinical and Biochemical Associations with Diabetic Retinopathy in Male Patients in the Gaza Strip

BACKGROUND

There are limited data on the prevalence and risk factors for diabetic retinopathy (DR) in the Gaza Strip.

OBJECTIVE

To assesses clinical and biochemical associated with DR in males with type 2 diabetes mellitus (T2DM) in the Gaza Strip.

METHODS

One hundred and fifty males with T2DM from the Gaza Strip underwent a questionnaire interview, serum biochemical analysis, and assessment of their previous urine and blood results.

RESULTS

The prevalence of DR was 24.7%. The duration of diabetes and prevalence of neuropathy, nephropathy, cardiovascular disease, and recurrent infections were significantly higher among patients with DR compared with those without DR (p < 0.05). Serum urea, creatinine, glucose, cholesterol, and low-density lipoprotein cholesterol were significantly elevated, whilst eGFR and high-density lipoprotein cholesterol were significantly lower in patients with DR compared with patients without DR (p < 0.05). Urinary albumin concentration and albumin creatinine ratio (ACR) was higher in patients with DR. ACR correlated significantly with the duration of T2DM (r = 0.311, p < 0.001), glucose (r = 0.479, p < 0.001), urea (r = 0.337, p < 0.001), creatinine (r = 0.275, p = 0.001), and GFR (r = -0.275, p < 0.001).

CONCLUSION

These data show a high prevalence of DR in an unselected cohort of patients with T2DM and relationships to modifiable risk factors in Gaza.

Vision-Related Functional Burden of Diabetic Retinopathy Across Severity Levels in the United States

Importance

Among adults with diabetes in the United States, severe forms of diabetic retinopathy (DR) are significantly associated with a greater vision-related functional burden.

Objective

To assess the functional burden of DR across severity levels in the United States.

Design, Setting, and Participants

This cross-sectional study was based on 1004 participants 40 years or older with diabetes and valid ocular and sociodemographic outcomes in the National Health and Nutrition Examination Surveys (NHANES) (2005-2006 and 2007-2008). Diabetic retinopathy was based on fundus photograph grading, using the Early Treatment Diabetic Retinopathy Study severity scale. The analysis was performed from October 15, 2016, to June 15, 2017.

Main Outcomes and Measures

Functional difficulties secondary to vision were assessed during a household questionnaire in which participants self-reported difficulty with reading, visuospatial tasks (ie, close-up work or finding things on a crowded shelf), mobility (ie, walking down steps, stairs, or curbs), and driving. The main outcome measure was vision-related functional burden, which was defined as present for individuals reporting moderate or greater difficulty in any of the aforementioned tasks.

Results

Of the 1004 persons with diabetes analyzed for this study (mean age, 65.7 years [95% CI, 64.0-67.3 years]; 51.1% male [95% CI, 47.1-55.2] and 48.9% female [95% CI, 44.8-52.9]), the prevalence was 72.3% for no retinopathy, 25.4% for mild and moderate nonproliferative diabetic retinopathy (NPDR), and 2.3% for severe NPDR or proliferative diabetic retinopathy (PDR). The prevalence of vision-related functional burden was 20.2% (95% CI, 16.3%-24.1%) for those with no retinopathy, 20.4% (95% CI, 15.3%-27.8%) for those with mild and moderate NPDR, and 48.5% (95% CI, 25.6%-71.5%) for those with severe NPDR or PDR (P = .02). In multivariable analysis, the odds of vision-related functional burden were significantly greater among those with severe NPDR or PDR relative to those with no retinopathy (adjusted odds ratio [aOR], 3.59; 95% CI, 1.29-10.05; P = .02). Those with severe NPDR or PDR did not have a statistically significant greater odds of vision-related functional burden than did those with mild or moderate NPDR (aOR, 2.70; 95% CI, 0.93-7.78; P = .07).

Conclusions and Relevance

Among US adults with diabetes, approximately half of those with severe NPDR or PDR had difficulty with at least one visual function task. Moreover, vision-related functional burden was significantly greater among those with severe NPDR or PDR than among those with no retinopathy. These data suggest the importance of preventing severe forms of DR to mitigate the vision-related functional burden among US adults with diabetes. Future studies should complement our study by assessing the association of worsening retinopathy with objectively measured functional outcomes.

Effect of three-dimensional reconstruction-assisted 23G micro-invasive vitrectomy in patients with proliferative diabetic retinopathy

In the present study, we investigated the effect of optical coherence tomography (OCT) three-dimensional reconstruction-assisted 23G micro-invasive vitrectomy (abbreviated to'23G') in patients with proliferative diabetic retinopathy (PDR). A total of 66 PDR patients (66 eyes) were continuously selected and randomly divided into the control and observation groups with 33 patients in each group. Patients in the control group were treated with routine OCT examination while the patients in the observation group were treated with OCT three-dimensional retinal reconstruction. The 23G surgical method was applied to the two groups, and a comparison was made on the clinical effects in the two groups. The follow-up visits lasted for approximately 6 months, and it was found that the operative time, occurrence rate of intraoperative complications and postoperative complications as shown in the observation group were significantly less than those in the control group (P<0.05). The best corrected visual acuity (BCVA) was improved, the intraocular pressure was increased and retinal thickness was decreased after the treatment. The BCVA of patients in the observation group was significantly greater than that of patients in the control group while the intraocular pressure and retinal thickness of patients in the observation group were significantly less than those of patients in the control group (P<0.05). In conclusion, the effect of 23G surgical method in PDR patients can be improved and corresponding complications can be reduced under the assistance of OCT three-dimensional reconstruction.

MiR-126 overexpression inhibits high glucose-induced migration and tube formation of rhesus macaque choroid-retinal endothelial cells by obstructing VEGFA and PIK3R2

AIM

The aims of this study are to investigate the relative regulation between miR-126 and VEGF/PI3K/AKT signaling pathway in retinal vascular endothelial cells.

METHODS

Rhesus macaque choroid-retinal endothelial cell line (RF/6A) cells were cultured in high glucose to imitate the conditions occurring in DR. First, we detected the expression of miR-126, VEGFA and PIK3R2 in RF/6A cells on the condition of high glucose by q-PCR and western blot. Then, after addition of miR-126 mimics and miR-126 inhibitor, we investigated the function of miR-126 in RF/6A cells by scratch wound, Transwell migration and tube formation assays, and the effect of miR-126 on the expression of VEGFA, PIK3R2 and AKT. Moreover, bioinformatics analysis and luciferase array were used to confirm the direct or specific regulation of miR-126 to VEGFA or PIK3R2.

RESULTS

Here, first, we found that high glucose could induce the decrease of miR-126 and the increase of VEGFA and PIK3R2 in RF/6A. Then, by scratch wound, Transwell migration and tube formation assays, we found that miR-126 overexpression could inhibit the migration and sprouting of RF/6A cells induced by high glucose, while knockdown of miR-126 led to the opposite results. Moreover, overexpression of miR-126 inhibited the increased expression of VEGFA, PIK3R2, SDF-1α, VCAM-1, and SPRED1, and the activation of AKT1 induced by high glucose and miR-126 inhibitor caused the opposite results which were determined by q-PCR and western blot. In addition, by luciferase assay, we found that miR-126 could directly negatively regulate VEGFA and PIK3R2.

CONCLUSION

Our results suggest that miR-126 overexpression inhibits the migration and sprouting of RF/6A cells induced by high glucose which might possibly be by blocking VEGFA and PIK3R2 in the VEGF/PI3K/AKT signaling pathway.

Dietary Compound Chrysin Inhibits Retinal Neovascularization with Abnormal Capillaries in db/db Mice

Diabetic retinopathy (DR) develops in a significant proportion of patients with chronic diabetes, characterized by retinal macular edema and abnormal retinal vessel outgrowth leading to vision loss. Chrysin, a naturally-occurring flavonoid found in herb and honeycomb, has anti-inflammatory, antioxidant, and anti-cancer properties. This study sought to determine the protective effects of chrysin on retinal neovascularization with abnormal vessels and blood-retinal barrier (BRB) breakdown in 33 mM glucose-exposed human retinal endothelial cells and in db/db mouse eyes. High glucose caused retinal endothelial apoptotic injury, which was inhibited by submicromolar chrysin. This compound diminished the enhanced induction of HIF-1α, vascular endothelial growth factor (VEGF), and VEGF receptor-2 (VEGFR2) in high glucose-exposed retinal endothelial cells. Consistently, oral administration of 10 mg/kg chrysin reduced the induction of these proteins in db/db mouse eye tissues. In addition, chrysin restored the decrement of VE-cadherin and ZO-1 junction proteins and PECAM-1 in hyperglycemia-stimulated retinal endothelial cells and diabetic mouse retina, possibly maintaining tight cell-cell interactions of endothelial cells and pericytes. Anti-apoptotic chrysin reduced the up-regulation of Ang-1, Ang-2, and Tie-2 crucial to retinal capillary occlusion and BRB permeability. Furthermore, orally treating chrysin inhibited acellular capillary formation, neovascularization, and vascular leakage observed in diabetic retinas. These observations demonstrate, for the first time, that chrysin had a capability to encumber diabetes-associated retinal neovascularization with microvascular abnormalities and BRB breakdown.

Angiogenesis and Inflammation Crosstalk in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most prevalent microvascular complications of diabetes and one of the most frequent causes of blindness in active age. Etiopathogenesis behind this important complication is related to several biochemical, hemodynamic and endocrine mechanisms with a preponderant initial role assumed by polyol pathways, increment of growth factors, accumulation of advanced glycation end products (AGE), activation of protein kinase C (PKC), activation of the renin-angiotensin-aldosterone system (RAAS), and leukostasis. Chronic and sustained hyperglycemia works as a trigger to the early alterations that culminate in vascular dysfunction. Hypoxia also plays an essential role in disease progression with promotion of neovascularization and vascular dystrophies with vitreous hemorrhages induction. Thus, the accumulation of fluids and protein exudates in ocular cavities leads to an opacity augmentation of the cornea that associated to neurodegeneration results in vision loss, being this a devastating characteristic of the disease final stage. During disease progression, inflammatory molecules are produced and angiogenesis occur. Furthermore, VEGF is overexpressed by the maintained hyperglycemic environment and up-regulated by tissue hypoxia. Also pro-inflammatory mediators regulated by cytokines, such as tumor necrosis factor (TNF-α) and interleukin-1 beta (IL-1β), and growth factors leads to the progression of these processes, culminating in vasopermeability (diabetes macular edema) and/or pathological angiogenesis (proliferative diabetic retinopathy). It was found a mutual contribution between inflammation and angiogenesis along the process. J. Cell. Biochem. 117: 2443-2453, 2016. © 2016 Wiley Periodicals, Inc.

Advances in Gene Therapy for Diseases of the Eye

Over the last few years, huge progress has been made with regard to the understanding of molecular mechanisms underlying the pathogenesis of neurodegenerative diseases of the eye. Such knowledge has led to the development of gene therapy approaches to treat these devastating disorders. Challenges regarding the efficacy and efficiency of therapeutic gene delivery have driven the development of novel therapeutic approaches, which continue to evolve the field of ocular gene therapy. In this review article, we will discuss the evolution of preclinical and clinical strategies that have improved gene therapy in the eye, showing that treatment of vision loss has a bright future.