VEGF-targeting drugs for the treatment of retinal neovascularization in diabetic retinopathy

Key genes and regulatory networks for diabetic retinopathy based on hypoxia-related genes: a bioinformatics analysis

AIM

To prevent neovascularization in diabetic retinopathy (DR) patients and partially control disease progression.

METHODS

Hypoxia-related differentially expressed genes (DEGs) were identified from the GSE60436 and GSE102485 datasets, followed by gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. Potential candidate drugs were screened using the CMap database. Subsequently, a protein-protein interaction (PPI) network was constructed to identify hypoxia-related hub genes. A nomogram was generated using the rms R package, and the correlation of hub genes was analyzed using the Hmisc R package. The clinical significance of hub genes was validated by comparing their expression levels between disease and normal groups and constructing receiver operating characteristic curve (ROC) curves. Finally, a hypoxia-related miRNA-transcription factor (TF)-Hub gene network was constructed using the NetworkAnalyst online tool.

RESULTS

Totally 48 hypoxia-related DEGs and screened 10 potential candidate drugs with interaction relationships to upregulated hypoxia-related genes were identified, such as ruxolitinib, meprylcaine, and deferiprone. In addition, 8 hub genes were also identified: glycogen phosphorylase muscle associated (PYGM), glyceraldehyde-3-phosphate dehydrogenase spermatogenic (GAPDHS), enolase 3 (ENO3), aldolase fructose-bisphosphate C (ALDOC), phosphoglucomutase 2 (PGM2), enolase 2 (ENO2), phosphoglycerate mutase 2 (PGAM2), and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3). Based on hub gene predictions, the miRNA-TF-Hub gene network revealed complex interactions between 163 miRNAs, 77 TFs, and hub genes. The results of ROC showed that the except for GAPDHS, the area under curve (AUC) values of the other 7 hub genes were greater than 0.758, indicating their favorable diagnostic performance.

CONCLUSION

PYGM, GAPDHS, ENO3, ALDOC, PGM2, ENO2, PGAM2, and PFKFB3 are hub genes in DR, and hypoxia-related hub genes exhibited favorable diagnostic performance.

Intravitreal Antiangiogenic Treatment for Diabetic Retinopathy: A Mexican Real-Life Scenario Experience

The objective of this study was to analyze the effectiveness of two intravitreal antiangiogenic drugs, ranibizumab and aflibercept, in a Mexican population over a period of 5 years, evaluating the improvement in visual acuity (VA) and central retinal thickness (CRT) in a real-world scenario. This is a retrospective study with subjects diagnosed with diabetic retinopathy (DR), proliferative diabetic retinopathy (PDR), and diabetic macular edema (DME) receiving intravitreal injections of ranibizumab and/or aflibercept. In this study, we analyzed 588 eyes of 294 patients who received intravitreal antiangiogenic injections. The results showed an improvement regardless of antiangiogenic treatment or diagnosis in both VA and CRT. We found that both aflibercept and ranibizumab improved VA, while subjects with DME responded less to antiangiogenic treatment (p < 0.05), and that this difference did not correspond to the CRT measured by OCT. These results support evidence that intravitreal antiangiogenic medications are effective for ophthalmic complications of diabetes in our population; however, damage to visual structures is not reversed in most patients. And that the perception by the patient (VA) and that of the ophthalmologist (CRT) do not completely correlate in our study.

Prime Editing of Vascular Endothelial Growth Factor Receptor 2 Attenuates Angiogenesis In Vitro

Vascular endothelial growth factor receptor (VEGFR)-2 is a key switch for angiogenesis, which is observed in various human diseases. In this study, a novel system for advanced prime editing (PE), termed PE6h, is developed, consisting of dual lentiviral vectors: (1) a clustered regularly interspaced palindromic repeat-associated protein 9 (H840A) nickase fused with reverse transcriptase and an enhanced PE guide RNA and (2) a dominant negative (DN) MutL homolog 1 gene with nicking guide RNA. PE6h was used to edit VEGFR2 (c.18315T>A, 50.8%) to generate a premature stop codon (TAG from AAG), resulting in the production of DN-VEGFR2 (787 aa) in human retinal microvascular endothelial cells (HRECs). DN-VEGFR2 impeded VEGF-induced phosphorylation of VEGFR2, Akt, and extracellular signal-regulated kinase-1/2 and tube formation in PE6h-edited HRECs in vitro. Overall, our results highlight the potential of PE6h to inhibit angiogenesis in vivo.

Microglia in retinal angiogenesis and diabetic retinopathy

Diabetic retinopathy has a high probability of causing visual impairment or blindness throughout the disease progression and is characterized by the growth of new blood vessels in the retina at an advanced, proliferative stage. Microglia are a resident immune population in the central nervous system, known to play a crucial role in regulating retinal angiogenesis in both physiological and pathological conditions, including diabetic retinopathy. Physiologically, they are located close to blood vessels and are essential for forming new blood vessels (neovascularization). In diabetic retinopathy, microglia become widely activated, showing a distinct polarization phenotype that leads to their accumulation around neovascular tufts. These activated microglia induce pathogenic angiogenesis through the secretion of various angiogenic factors and by regulating the status of endothelial cells. Interestingly, some subtypes of microglia simultaneously promote the regression of neovascularization tufts and normal angiogenesis in neovascularization lesions. Modulating the state of microglial activation to ameliorate neovascularization thus appears as a promising potential therapeutic approach for managing diabetic retinopathy.

Exploitation of enhanced prime editing for blocking aberrant angiogenesis

INTRODUCTION

Aberrant angiogenesis plays an important part in the development of a variety of human diseases including proliferative diabetic retinopathy, with which there are still numerous patients remaining a therapeutically challenging condition. Prime editing (PE) is a versatile gene editing approach, which offers a novel opportunity to genetically correct challenging disorders.

OBJECTIVES

The goal of this study was to create a dominant-negative (DN) vascular endothelial growth factor receptor (VEGFR) 2 by editing genomic DNA with an advanced PE system to block aberrant retinal angiogenesis in a mouse model of oxygen-induced retinopathy.

METHODS

An advanced PE system (referred to as PE6x) was established within two lentiviral vectors, with one carrying an enhanced PE guide RNA and a canonical Cas9 nickase fused with an optimized reversal transcriptase, and the other conveying a nicking guide RNA and a DN-MLH1 to improve PE efficiency. Dual non-integrating lentiviruses (NILVs) produced with the two lentiviral PE6x vectors were then employed to create a mutation of VEGFR2 T17967A by editing the Mus musculus VEGFR2 locus in vitro and in vivo, leading to generation of a premature stop codon (TAG, K796stop) to produce DN-VEGFR2, to interfere with the wild type VEGFR2 which is essential for angiogenesis.

RESULTS

NILVs targeting VEGFR2 delivered into cultured murine vascular endothelial cells led to 51.06 % VEGFR2 T17967A in the genome analyzed by next generation sequencing and the production of DN-VEGFR2, which was found to hamper VEGF-induced VEGFR2 phosphorylation, as demonstrated by Western blot analysis. Intravitreally injection of the dual NILVs into postnatal day 12 mice in a model of oxygen-induced retinopathy, led to production of retinal DN-VEGFR2 in postnatal day 17 mice which blocked retinal VEGFR2 expression and activation as well as abnormal retinal angiogenesis without interfering with retinal structure and function, as assessed by electroretinography, optical coherence tomography, fundus fluorescein angiography and histology.

CONCLUSION

DN-VEGFR2 resulted from editing genomic VEGFR2 using the PE6x system can be harnessed to treat intraocular pathological angiogenesis.

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.

Cell and molecular targeted therapies for diabetic retinopathy

Diabetic retinopathy (DR) stands as a prevalent complication in the eye resulting from diabetes mellitus, predominantly associated with high blood sugar levels and hypertension as individuals age. DR is a severe microvascular complication of both type I and type II diabetes mellitus and the leading cause of vision impairment. The critical approach to combatting and halting the advancement of DR lies in effectively managing blood glucose and blood pressure levels in diabetic patients; however, this is seldom achieved. Both human and animal studies have revealed the intricate nature of this condition involving various cell types and molecules. Aside from photocoagulation, the sole therapy targeting VEGF molecules in the retina to prevent abnormal blood vessel growth is intravitreal anti-VEGF therapy. However, a substantial portion of cases, approximately 30-40%, do not respond to this treatment. This review explores distinctive pathophysiological phenomena of DR and identifiable cell types and molecules that could be targeted to mitigate the chronic changes occurring in the retina due to diabetes mellitus. Addressing the significant research gap in this domain is imperative to broaden the treatment options available for managing DR effectively.

Dual anti-angiogenic and anti-inflammatory action of tRNA-Cys-5-0007 in ocular vascular disease

BACKGROUND

Intravitreal injections of angiogenesis inhibitors have proved efficacious in the majority of patients with ocular angiogenesis. However, one-fourth of all treated patients fail to derive benefits from intravitreal injections. tRNA-derived small RNA (tsRNA) emerges as a crucial class of non-coding RNA molecules, orchestrating key roles in the progression of human diseases by modulating multiple targets. Through our prior sequencing analyses and bioinformatics predictions, tRNA-Cys-5-0007 has shown as a potential regulator of ocular angiogenesis. This study endeavors to elucidate the precise role of tRNA-Cys-5-0007 in the context of ocular angiogenesis.

METHODS

Quantitative reverse transcription PCR (qRT-PCR) assays were employed to detect tRNA-Cys-5-0007expression. EdU assays, sprouting assays, transwell assays, and Matrigel assays were conducted to elucidate the involvement of tRNA-Cys-5-0007 in endothelial angiogenic effects. STZ-induced diabetic model, OIR model, and laser-induced CNV model were utilized to replicate the pivotal features of ocular vascular diseases and evaluate the influence of tRNA-Cys-5-0007 on ocular angiogenesis and inflammatory responses. Bioinformatics analysis, luciferase activity assays, RNA pull-down assays, and in vitro studies were employed to elucidate the anti-angiogenic mechanism of tRNA-Cys-5-0007. Exosomal formulation was employed to enhance the synergistic anti-angiogenic and anti-inflammatory efficacy of tRNA-Cys-5-0007.

RESULTS

tRNA-Cys-5-0007 expression was down-regulated under angiogenic conditions. Conversely, tRNA-Cys-5-0007 overexpression exhibited anti-angiogenic effects in retinal endothelial cells, as evidenced by reduced proliferation, sprouting, migration, and tube formation abilities. In diabetic, laser-induced CNV, and OIR models, tRNA-Cys-5-0007 overexpression led to decreased ocular vessel leakage, inhibited angiogenesis, and reduced ocular inflammation. Mechanistically, these effects were attributed to the targeting of vascular endothelial growth factor A (VEGFA) and TGF-β1 by tRNA-Cys-5-0007. The utilization of an exosomal formulation further potentiated the synergistic anti-angiogenic and anti-inflammatory efficacy of tRNA-Cys-5-0007.

CONCLUSIONS

Concurrent targeting of tRNA-Cys-5-0007 for anti-angiogenic and anti-inflammatory therapy holds promise for enhancing the effectiveness of current anti-angiogenic therapy.

Exosomal lncRNA-MIAT promotes neovascularization via the miR-133a-3p/MMP-X1 axis in diabetic retinopathy

Diabetic retinopathy (DR), a most common microangiopathy of diabetes, causes vision loss and even blindness. The mechanisms of exosomal lncRNA remain unclear in the development of DR. Here, we first identifed the pro-angiogenic effect of exosomes derived from vitreous humor of proliferative diabetic retinopathy patients, where lncRNA-MIAT was enriched inside. Secondly, lncRNA-MIAT was demonstrated significantly increased in exosomes from high glucose induced human retinal vascular endothelial cell, and can regulate tube formation, migration and proliferation ability to promote angiogenesis in vitro and in vivo. Mechanistically, the pro-angiogenic effect of lncRNA-MIAT was via the lncRNA-MIAT/miR-133a-3p/MMP-X1 axis. The reduced level of lncRNA-MIAT in this axis mitigated the generation of retinal neovascular in mouse model of oxygen-induced retinopathy (OIR), providing crucial evidence for lncRNA-MIAT as a potential clinical target. These findings enhance our understanding of the role of exosomal lncRNA-MIAT in retinal angiogenesis, and propose a promising therapeutic strategy against diabetic retinopathy.

LncRNA XIST promotes neovascularization in diabetic retinopathy by regulating miR-101-3p/VEGFA

Objective

This study sought to investigate the regulation of long noncoding RNA (lncRNA) XIST on the microRNA (miR)-101-3p/vascular endothelial growth factor A (VEGFA) axis in neovascularization in diabetic retinopathy (DR).

Materials and methods

Serum of patients with DR was extracted for the analysis of XIST, miR-101-3p, and VEGFA expression levels. High glucose (HG)-insulted HRMECs and DR model rats were treated with lentiviral vectors. MTT, transwell, and tube formation assays were performed to evaluate cell viability, migration, and angiogenesis, and ELISA was conducted to detect the levels of inflammatory cytokines. Dual-luciferase reporter, RIP, and RNA pull-down experiments were used to validate the relationships among XIST, miR-101-3p, and VEGFA.

Results

XIST and VEGFA were upregulated and miR-101-3p was downregulated in serum from patients with DR. XIST knockdown inhibited proliferation, migration, vessel tube formation, and inflammatory responsein HG-treated HRMECs, whereas the above effects were nullified by miR-101-3p inhibition or VEGFA overexpression. miR-101-3p could bind to XIST and VEGFA. XIST promoted DR development in rats by regulating the miR-101-3p/VEGFA axis.

Conclusion

LncRNA XIST promotes VEGFA expression by downregulating miR-101-3p, thereby stimulating angiogenesis and inflammatory response in DR.

Eye Diseases: When the Solution Comes from Plant Alkaloids

Plants are an incredible source of metabolites showing a wide range of biological activities. Among these, there are the alkaloids, which have been exploited for medical purposes since ancient times. Nowadays, many plant-derived alkaloids are the main components of drugs used as therapy for different human diseases. This review deals with providing an overview of the alkaloids used to treat eye diseases, describing the historical outline, the plants from which they are extracted, and the clinical and molecular data supporting their therapeutic activity. Among the different alkaloids that have found application in medicine so far, atropine and pilocarpine are the most characterized ones. Conversely, caffeine and berberine have been proposed for the treatment of different eye disorders, but further studies are still necessary to fully understand their clinical value. Lastly, the alkaloid used for managing hypertension, reserpine, has been recently identified as a potential drug for ameliorating retinal disorders. Other important aspects discussed in this review are different solutions for alkaloid production. Given that the industrial production of many of the plant-derived alkaloids still relies on extraction from plants, and the chemical synthesis can be highly expensive and poorly efficient, alternative methods need to be found. Biotechnologies offer a multitude of possibilities to overcome these issues, spanning from genetic engineering to synthetic biology for microorganisms and bioreactors for plant cell cultures. However, further efforts are needed to completely satisfy the pharmaceutical demand.

Recent development of VEGFR small molecule inhibitors as anticancer agents: A patent review (2021-2023)

VEGFR, a receptor tyrosine kinase inhibitor (TKI), is an important regulatory factor that promotes angiogenesis and vascular permeability. It plays a significant role in processes such as tumor angiogenesis, tumor cell invasion, and metastasis. VEGFR is mainly composed of three subtypes: VEGFR-1, VEGFR-2, and VEGFR-3. Among them, VEGFR-2 is the crucial signaling receptor for VEGF, which is involved in various pathological and physiological functions. At present, VEGFR-2 is closely related to a variety of cancers, such as non-small cell lung cancer (NSCLC), Hepatocellular carcinoma, Renal cell carcinoma, breast cancer, gastric cancer, glioma, etc. Consequently, VEGFR-2 serves as a crucial target for various cancer treatments. An increasing number of VEGFR inhibitors have been discovered to treat cancer, and they have achieved tremendous success in the clinic. Nevertheless, VEGFR inhibitors often exhibit severe cytotoxicity, resistance, and limitations in indications, which weaken the clinical therapeutic effect. In recent years, many small molecule inhibitors targeting VEGFR have been identified with anti-drug resistance, lower cytotoxicity, and better affinity. Here, we provide an overview of the structure and physiological functions of VEGFR, as well as some VEGFR inhibitors currently in clinical use. Also, we summarize the in vivo and in vitro activities, selectivity, structure-activity relationship, and therapeutic or preventive use of VEGFR small molecule inhibitors reported in patents in the past three years (2021-2023), thereby presenting the prospects and insights for the future development of targeted VEGFR inhibitors.

Biochemical Changes in Anterior Chamber of the Eye in Diabetic Patients-A Review

This article aims to provide a comprehensive review of the biochemical changes observed in the anterior chamber of the eye in diabetic patients. The increased levels of inflammatory markers, alterations in antioxidant defense mechanisms, and elevated levels of advanced glycation end products (AGEs) in the aqueous humor (AH) are explored. Additionally, the impact of these biochemical changes on diabetic retinopathy progression, increased intraocular pressure, and cataract formation is discussed. Furthermore, the diagnostic and therapeutic implications of these findings are presented. This study explores potential biomarkers for detecting diabetic eye disease at an early stage and monitoring its progression. An investigation of the targeting of inflammatory and angiogenic pathways as a potential treatment approach and the role of antioxidant agents in managing these biochemical changes is performed.

Transcriptional patterns of human retinal pigment epithelial cells under protracted high glucose

BACKGROUND

The retinal pigment epithelium (RPE) is essential for retinal homeostasis. Comprehensively exploring the transcriptional patterns of diabetic human RPE promotes the understanding of diabetic retinopathy (DR).

METHODS AND RESULTS

A total of 4125 differentially expressed genes (DEGs) were screened out from the human primary RPE cells subjected to prolonged high glucose (HG). The subsequent bioinformatics analysis is divided into 3 steps. In Step 1, 21 genes were revealed by intersecting the enriched genes from the KEGG, WIKI, and Reactome databases. In Step 2, WGCNA was applied and intersected with the DEGs. Further intersection based on the enrichments with the GO biological processes, GO cellular components, and GO molecular functions databases screened out 12 candidate genes. In Step 3, 13 genes were found to be simultaneously up-regulated in the DEGs and a GEO dataset involving human diabetic retinal tissues. VEGFA and ERN1 were the 2 starred genes finally screened out by overlapping the 3 Steps.

CONCLUSION

In this study, multiple genes were identified as crucial in the pathological process of RPE under protracted HG, providing potential candidates for future researches on DR. The current study highlights the importance of RPE in DR pathogenesis.

Transcription Factor EGR1 Facilitates Neovascularization in Mice with Retinopathy of Prematurity by Regulating the miR-182-5p/EFNA5 Axis

Neovascularization is the hallmark of retinopathy of prematurity (ROP). Early growth response 1 (EGR1) has been reported as an angiogenic factor. This study was conducted to probe the regulatory mechanism of EGR1 in neovascularization in ROP model mice. The ROP mouse model was established, followed by determination of EGR1 expression and assessment of neovascularization [vascular endothelial growth factor-A (VEGF-A) and pigment epithelium-derived factor (PEDF)]. Retinal vascular endothelial cells were cultured and treated with hypoxia, followed by the tube formation assay. The state of oxygen induction was assessed by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot assay to determine hypoxia-inducible factor 1-alpha (HIF-1A). The levels of microRNA (miRNA)-182-5p and ephrin-A5 (EFNA5) in tissues and cells were determined by RT-qPCR. Chromatin immunoprecipitation and dual-luciferase assay were used to validate gene interaction. EGR1 and EFNA5 were upregulated in the retina of ROP mice while miR-182-5p was downregulated. EGR1 knockdown decreased VEGF-A and HIF-1A expression and increased PEDF expression in the retina of ROP mice. In vitro, EGR1 knockdown also reduced neovascularization. EGR1 binding to the miR-182-5p promoter inhibited miR-182-5p transcription and further promoted EFNA5 transcription. miR-182-5p downregulation or EFNA5 overexpression averted the inhibition of neovascularization caused by EGR1 downregulation. Overall, EGR1 bound to the miR-182-5p promoter to inhibit miR-182-5p transcription and further promoted EFNA5 transcription, thus promoting retinal neovascularization in ROP mice.

Redox Regulation of Immunometabolism in Microglia Underpinning Diabetic Retinopathy

Diabetic retinopathy (DR) is the leading cause of visual impairment and blindness among the working-age population. Microglia, resident immune cells in the retina, are recognized as crucial drivers in the DR process. Microglia activation is a tightly regulated immunometabolic process. In the early stages of DR, the M1 phenotype commonly shifts from oxidative phosphorylation to aerobic glycolysis for energy production. Emerging evidence suggests that microglia in DR not only engage specific metabolic pathways but also rearrange their oxidation-reduction (redox) system. This redox adaptation supports metabolic reprogramming and offers potential therapeutic strategies using antioxidants. Here, we provide an overview of recent insights into the involvement of reactive oxygen species and the distinct roles played by key cellular antioxidant pathways, including the NADPH oxidase 2 system, which promotes glycolysis via enhanced glucose transporter 4 translocation to the cell membrane through the AKT/mTOR pathway, as well as the involvement of the thioredoxin and nuclear factor E2-related factor 2 antioxidant systems, which maintain microglia in an anti-inflammatory state. Therefore, we highlight the potential for targeting the modulation of microglial redox metabolism to offer new concepts for DR treatment.

Ocular pharmacological and biochemical profiles of 6-thioguanine: a drug repurposing study

Introduction

The purine analog 6-thioguanine (6TG), an old drug approved in the 60s to treat acute myeloid leukemia (AML), was tested in the diabetic retinopathy (DR) experimental in vivo setting along with a molecular modeling approach.

Methods

A computational analysis was performed to investigate the interaction of 6TG with MC1R and MC5R. This was confirmed in human umbilical vein endothelial cells (HUVECs) exposed to high glucose (25 mM) for 24 h. Cell viability in HUVECs exposed to high glucose and treated with 6TG (0.05-0.5-5 µM) was performed. To assess tube formation, HUVECs were treated for 24 h with 6TG 5 µM and AGRP (0.5-1-5 µM) or PG20N (0.5-1-5-10 µM), which are MC1R and MC5R antagonists, respectively. For the in vivo DR setting, diabetes was induced in C57BL/6J mice through a single streptozotocin (STZ) injection. After 2, 6, and 10 weeks, diabetic and control mice received 6TG intravitreally (0.5-1-2.5 mg/kg) alone or in combination with AGRP or PG20N. Fluorescein angiography (FA) was performed after 4 and 14 weeks after the onset of diabetes. After 14 weeks, mice were euthanized, and immunohistochemical analysis was performed to assess retinal levels of CD34, a marker of endothelial progenitor cell formation during neo-angiogenesis.

Results

The computational analysis evidenced a more stable binding of 6TG binding at MC5R than MC1R. This was confirmed by the tube formation assay in HUVECs exposed to high glucose. Indeed, the anti-angiogenic activity of 6TG was eradicated by a higher dose of the MC5R antagonist PG20N (10 µM) compared to the MC1R antagonist AGRP (5 µM). The retinal anti-angiogenic effect of 6TG was evident also in diabetic mice, showing a reduction in retinal vascular alterations by FA analysis. This effect was not observed in diabetic mice receiving 6TG in combination with AGRP or PG20N. Accordingly, retinal CD34 staining was reduced in diabetic mice treated with 6TG. Conversely, it was not decreased in diabetic mice receiving 6TG combined with AGRP or PG20N.

Conclusion

6TG evidenced a marked anti-angiogenic activity in HUVECs exposed to high glucose and in mice with DR. This seems to be mediated by MC1R and MC5R retinal receptors.

Thermosensitive In Situ Gelling Poloxamers/Hyaluronic Acid Gels for Hydrocortisone Ocular Delivery

This study endeavored to overcome the physiological barriers hindering optimal bioavailability in ophthalmic therapeutics by devising drug delivery platforms that allow therapeutically effective drug concentrations in ocular tissues for prolonged times. Thermosensitive drug delivery platforms were formulated by blending poloxamers (F68 and F127) with low-molecular-weight hyaluronic acid (HA) in various concentrations and loaded with hydrocortisone (HC). Among the formulations examined, only three were deemed suitable based on their desirable gelling properties at a temperature close to the eye's surface conditions while also ensuring minimal gelation time for swift ocular application. Rheological analyses unveiled the ability of the formulations to develop gels at suitable temperatures, elucidating the gel-like characteristics around the physiological temperature essential for sustained drug release. The differential scanning calorimetry findings elucidated intricate hydrogel-water interactions, indicating that HA affects the water-polymer interactions within the gel by increasing the platform hydrophilicity. Also, in vitro drug release studies demonstrated significant hydrocortisone release within 8 h, governed by an anomalous transport mechanism, prompting further investigation for optimized release kinetics. The produced platforms offer promising prospects for efficacious ocular drug delivery, addressing pivotal challenges in ocular therapeutics and heralding future advancements in the domain.

High Vasohibin-2 expression correlated with autophagy in proliferative diabetic retinopathy

Vasohibin-2 (VASH2) is confirmed to be associated with angiogenesis. To investigate the vitreous levels of VASH2 and how VASH2 induces angiogenesis in proliferative diabetic retinopathy (PDR), a total of 120 eyes were enrolled in this prospective and randomized controlled study and the vitreous level of VASH2 was quantified by Luminex liquid suspension chip. Vector systems were applied in human retinal microvascular endothelial cells (HRMECs) for VASH2 gene overexpression, along with interfering lentiviral vectors (VASH2-shRNA) for VASH2 gene silencing. Cell migration, autophagic flux, as well as the expression of α-tubulin, detyrosinated ⍺-tubulin, LC3 II/LC3 I, P62 were detected under normal, VASH2 overexpression, or interference conditions. The level of VASH2 in PDR patients was significantly higher (218.61 ± 30.14 pg/ml) than that in ERM/MH patients (80.78 ± 2.05 pg/ml) (P = 0.001). The migration ability of HRMECs was significantly increased in VASH2 overexpression group, while in the interfering group, the migration ability decreased. VASH2 increased the detyrosination of ⍺-tubulin. The high fluorescence intensity of autophagic flux showed an activation of autophagy in VASH2 overexpression group, which was also confirmed by the increase of LC3 II/LC3 I ratio and the decrease of P62. Collectively, the present study shows in PDR, vitreous level of VASH2 is higher. VASH2 promotes neovascularization by inducing autophagy, suggesting VASH2 could be a new anti-angiogenic drug target for PDR.

Chondroitin sulfate-modified antiangiogenic peptide conjugate induces cell apoptosis via the mitochondria-mediated pathway to perform antitumor activity

Tumor growth and metastasis heavily rely on angiogenesis, crucial for solid tumor development. Inhibiting angiogenesis associated with tumors emerges as a potent therapeutic approach. Our previous work synthesized the chondroitin sulfate-modified antiangiogenic peptide CS-ES2-AF (CS-EA), which exhibited better antiangiogenic activity, longer half-life, and more robust targeting. In this work, we further evaluated the stability in vitro, cellular uptake mechanism, cell apoptosis mechanism, antitumor activity in vivo, and safety of CS-EA. The stability of CS-EA was consistently superior to that of EA at different temperatures and in different pH ranges. Furthermore, CS-EA mainly entered EAhy926 cells through the clathrin-mediated endocytosis pathway. CS-EA inhibited endothelial cell proliferation, and induced cell apoptosis through downregulating the Bcl-2, reducing mitochondria membrane potential, upregulating cytochrome c, Caspase 3, and reactive oxygen species levels. CS-EA showed better antitumor activity in the B16 xenografted tumor model, with a tumor inhibition rate 1.92 times higher than EA. Simultaneously, it was observed that CS-EA did not cause any harmful effects on the vital organs of the mice. These findings indicate that CS-EA holds significant promise for the treatment of tumors.

Parallelism and non-parallelism in diabetic nephropathy and diabetic retinopathy

Diabetic nephropathy (DN) and diabetic retinopathy (DR), as microvascular complications of diabetes mellitus, are currently the leading causes of end-stage renal disease (ESRD) and blindness, respectively, in the adult working population, and they are major public health problems with social and economic burdens. The parallelism between the two in the process of occurrence and development manifests in the high overlap of disease-causing risk factors and pathogenesis, high rates of comorbidity, mutually predictive effects, and partial concordance in the clinical use of medications. However, since the two organs, the eye and the kidney, have their unique internal environment and physiological processes, each with specific influencing molecules, and the target organs have non-parallelism due to different pathological changes and responses to various influencing factors, this article provides an overview of the parallelism and non-parallelism between DN and DR to further recognize the commonalities and differences between the two diseases and provide references for early diagnosis, clinical guidance on the use of medication, and the development of new drugs.

Serum and Vitreous Levels of Placenta Growth Factor in Diabetic Retinopathy Patients: Correlation With Disease Severity and Optical Coherence Tomographic Parameters

Purpose The primary objective of this study was to compare placenta growth factor (PlGF) levels in the serum and vitreous of diabetic retinopathy (DR) patients to non-diabetic controls. Additionally, the study aimed to establish associations between serum and vitreous PlGF concentrations and to examine the correlation between vitreous PlGF in DR patients and morphological parameters. Methods This study included serum and vitreous samples from 38 patients, including 21 patients with DR and 17 non-diabetic controls. The control group included non-diabetic patients with rhegmatogenous retinal detachment with retinal tears secondary to posterior vitreous detachment or trauma. PlGF levels were quantified in vitreous and serum samples using an enzyme-linked immunosorbent assay (ELISA). Optical coherence tomography (OCT) scans from DR patients were evaluated to measure the central retinal thickness (CRT) and macular volume (MV). Results DR patients had significantly higher mean vitreous PlGF levels compared to non-DR patients (70.0±39.2 vs. 46.47±9.7 pg/mL, p-value=0.004). However, no significant increase in mean serum PlGF levels was observed in DR patients (p-value=0.232). Within the DR group, proliferative DR (PDR) patients presented significantly higher vitreous PlGF levels than non-PDR (NPDR) patients (76.5±41.0 vs. 42.5±5.0 pg/mL, p-value=0.009). There was no association between serum and vitreous PlGF levels. The correlation between vitreous PlGF levels and morphological parameters was rsp=0.175, p-value=0.488 for CRT, and rsp=0.288, p-value=0.262 for MV. Conclusion This study emphasizes the important role of PlGF in neovascularization, specifically highlighting its overexpression exclusively in vitreous from PDR patients. The observed increase in PlGF levels may be indicative of disease severity. The lack of correlation between vitreous and serum PlGF levels suggests a potential dissociation between intravitreal and systemic PlGF synthesis. Consequently, targeting PlGF in therapeutic approaches may offer an additional strategy for ocular pathologies with a neovascular component.

Recent Insights into the Etiopathogenesis of Diabetic Retinopathy and Its Management

Purpose: Diabetic retinopathy (DR) is a microvascular retinal disease associated with chronic diabetes mellitus, characterized by the damage of blood vessels in the eye. It is projected to become the leading cause of blindness, given the increasing burden of the diabetic population worldwide. The diagnosis and management of DR pose significant challenges for physicians because of the involvement of multiple biochemical pathways and the complexity of ocular tissues. This review aims to provide a comprehensive understanding of the molecular pathways implicated in the pathogenesis of DR, including the polyo pathway, hexosamine pathway, protein kinase C (PKC), JAK/STAT signaling pathways, and the renin-angiotensin system (RAS). Methods: Academic databases such as PubMed, Scopus, Google Scholar and Web of Science was systematically searched using a carefully constructed search strategy incorporating keywords like "Diabetic Retinopathy," "Molecular Pathways," "Pharmacological Treatments," and "Clinical Trials" to identify relevant literature for the comprehensive review. Results: In addition to activating other inflammatory cascades, these pathways contribute to the generation of oxidative stress within the retina. Furthermore, it aims to explore the existing pharmacotherapy options available for the treatment of DR. In addition to conventional pharmacological therapies such as corticosteroids, antivascular endothelial growth factors, and nonsteroidal anti-inflammatory drugs (NSAIDs), this review highlights the potential of repurposed drugs, phyto-pharmaceuticals, and novel pipeline drugs currently undergoing various stages of clinical trials. Conclusion: Overall, this review serves as a technical exploration of the complex nature of DR, highlighting both established and emerging molecular pathways implicated in its pathogenesis. Furthermore, it delves into the available pharmacological treatments, as well as the promising repurposed drugs, phyto-pharmaceuticals, and novel drugs currently being evaluated in clinical trials, with a focus on their specific mechanisms of action.

Refining vitrectomy for proliferative diabetic retinopathy

Pars plana vitrectomy (PPV) is the main treatment modality for patients with severe diabetic retinopathy. With the development of systems for microincision, wide-angle viewing, digitally assisted visualization, and intraoperative optical coherence tomography, contemporary PPV for diabetic retinopathy has been performed on a wider range of indications than previously considered. In this article, we reviewed, in conjunction with our collective experiences with Asian patients, the applications of new technologies for PPV in eyes with diabetic retinopathy and highlighted several important procedures and entities not generally reiterated in the literature, in order for vitreoretinal surgeons to optimize their approaches when facing the challenges imposed by the complications in diabetic eyes.

Quantitative response of macular neovascularisation to loading phase of aflibercept in neovascular age-related macular degeneration

PURPOSE

To evaluate quantitative morphological changes in macular neovascularisation (MNV) network after aflibercept therapy in neovascular age-related macular degeneration (nAMD) patients.

METHODS

Consecutive treatment-naïve patients with optical coherence tomography (OCT) angiography confirmed MNV due to nAMD who completed a loading phase of intravitreal aflibercept injections. A quantitative analysis of the vascular network remodelling was performed using a computational software (Angiotool).

RESULTS

A total of 53 eyes of 52 patients were included in the analysis. The total MNV area decreased significantly after three aflibercept injections (p = 0.003). Total vessel area and vessel density decreased respectively of 20% and 12% at V3 (p < 0.001 in both cases). Other parameters that reduced significantly were total vessel length, average vessel length and density of vascular junctions (p = 0.018, p = 0.002, and p = 0.044, respectively). The number of vascular endpoints (p = 0.001) and lacunarity (p = 0.011) increased significantly, whilst the number of vascular junctions did not vary significantly (p = 0.068). Changes in vascular metrics were predominantly driven by MNV type 1 and 2. No clear relationship was observed between any of the vascular metrics and the macular fluid status.

CONCLUSION

Although objective quantification of vascular parameters showed a significant remodelling of the MNV post-loading phase of aflibercept in type 1 and 2 MNV subtypes, none of the quantified vascular metrics correlated to the macular fluid response. These findings highlight a dissociation of anti-angiogenic and anti-permeability properties of aflibercept therapy during the loading phase.

Subconjunctival therapy by cubic liquid crystalline nanoparticles to deliver Triamcinolone acetonide for the management of diabetic Retinopathy: In vivo evidences

The expression of inflammatory markers and vascular endothelial growth factor (VEGF) was found to be upregulated in various posterior ocular disorders, including diabetic retinopathy (DR). Effective delivery of therapeutic agents to the retina poses a significant challenge in ophthalmic drug delivery due to biological ocular barriers. Triamcinolone acetonide (TA) was selected as the model corticosteroid drug targeting cytokines and VEGF in DR. However, despite TA's low molecular weight and hydrophobicity, which enable it to bypass the conjunctival epithelial barrier, it doesn't efficiently exert its effect at the target site. Nanocarriers have emerged as a solution to enhance drug delivery to the retina and improve bioavailability. This study aimed to compare the effects of Triamcinolone-loaded cubic liquid crystalline nanoparticles (TA-cubic LCNPs) and TA-Suspension in an experimental DR model administered via the subconjunctival (SCJ) route. The results demonstrated that TA-cubic LCNPs enhanced TA periocular delivery efficacy by reducing inflammatory and VEGF markers through the advanced glycation end products (AGE)/protein kinase C pathway. They were identified as promising nano-carriers, exhibiting potential for targeted delivery to the retina.

Integration of systematic review, lipidomics with experiment verification reveals abnormal sphingolipids facilitate diabetic retinopathy by inducing oxidative stress on RMECs

OBJECTIVE

This study aims to explore the potential biomarkers in the development of diabetes mellitus (DM) into diabetic retinopathy (DR).

METHODS

Systematic review of diabetic metabolomics was used to screen the differential metabolites and related pathways during the development of DM. Non-targeted lipidomics of rat plasma was performed to explore the differential metabolites in the development of DM into DR in vivo. To verify the effects of differential metabolites in inducing retinal microvascular endothelial cells (RMECs) injury by increasing oxidative stress, high glucose medium containing differential metabolites was used to induce rat RMECs injury and cell viability, malondialdehyde (MDA) contents, superoxide dismutase (SOD) activities, reactive oxygen species (ROS) levels and mitochondrial membrane potential (MMP) were evaluated in vitro. Network pharmacology was performed to explore the potential mechanism of differential metabolites in inducing DR.

RESULTS

Through the systematic review, 148 differential metabolites were obtained and the sphingolipid metabolic pathway attracted our attention. Plasma non-targeted lipidomics found that sphingolipids were accompanied by the development of DM into DR. In vitro experiments showed sphinganine and sphingosine-1-phosphate aggravated rat RMECs injury induced by high glucose, further increased MDA and ROS levels, and further decreased SOD activities and MMP. Network pharmacology revealed sphinganine and sphingosine-1-phosphate may induce DR by regulating the AGE-RAGE and HIF-1 signaling pathways.

CONCLUSIONS

Integrated systematic review, lipidomics and experiment verification reveal that abnormal sphingolipid metabolism facilitates DR by inducing oxidative stress on RMECs. Our study could provide the experimental basis for finding potential biomarkers for the diagnosis and treatment of DR.

The Role of Genetic Polymorphisms in Diabetic Retinopathy: Narrative Review

Diabetic retinopathy (DR) is renowned as a leading cause of visual loss in working-age populations with its etiopathology influenced by the disturbance of biochemical metabolic pathways and genetic factors, including gene polymorphism. Metabolic pathways considered to have an impact on the development of the disease, as well as genes and polymorphisms that can affect the gene expression, modify the quantity and quality of the encoded product (protein), and significantly alter the metabolic pathway and its control, and thus cause changes in the functioning of metabolic pathways. In this article, the screening of chromosomes and the most important genes involved in the etiology of diabetic retinopathy is presented. The common databases with manuscripts published from January 2000 to June 2023 have been taken into consideration and chosen. This article indicates the role of specific genes in the development of diabetic retinopathy, as well as polymorphic changes within the indicated genes that may have an impact on exacerbating the symptoms of the disease. The collected data will allow for a broader look at the disease and help to select candidate genes that can become markers of the disease.

Advances and Perspectives in Relation to the Molecular Basis of Diabetic Retinopathy-A Review

Diabetes mellitus (DM) is a growing problem nowadays, and diabetic retinopathy (DR) is its predominant complication. Currently, DR diagnosis primarily relies on fundoscopic examination; however, novel biomarkers may facilitate that process and make it widely available. In this current review, we delve into the intricate roles of various factors and mechanisms in DR development, progression, prediction, and their association with therapeutic approaches linked to the underlying pathogenic pathways. Specifically, we focus on advanced glycation end products, vascular endothelial growth factor (VEGF), asymmetric dimethylarginine, endothelin-1, and the epigenetic regulation mediated by microRNAs (miRNAs) in the context of DR.

Role of exosome-derived miRNAs in diabetic wound angiogenesis

Chronic wounds with high disability are among the most common and serious complications of diabetes. Angiogenesis dysfunction impair wound healing in patients with diabetes. Compared with traditional therapies that can only provide symptomatic treatment, stem cells-owing to their powerful paracrine properties, can alleviate the pathogenesis of chronic diabetic wounds and even cure them. Exosome-derived microRNAs (miRNAs), important components of stem cell paracrine signaling, have been reported for therapeutic use in various disease models, including diabetic wounds. Exosome-derived miRNAs have been widely reported to be involved in regulating vascular function and have promising applications in the repair and regeneration of skin wounds. Therefore, this article aims to review the current status of the pathophysiology of exosome-derived miRNAs in the diabetes-induced impairment of wound healing, along with current knowledge of the underlying mechanisms, emphasizing the regulatory mechanism of angiogenesis, we hope to document the emerging theoretical basis for improving wound repair by restoring angiogenesis in diabetes.

Transition metals in angiogenesis - A narrative review

The aim of this paper is to offer a narrative review of the literature regarding the influence of transition metals on angiogenesis, excluding lanthanides and actinides. To our knowledge there are not any reviews up to date offering such a summary, which inclined us to write this paper. Angiogenesis describes the process of blood vessel formation, which is an essential requirement for human growth and development. When the complex interplay between pro- and antiangiogenic mediators falls out of balance, angiogenesis can quickly become harmful. As it is so fundamental, both its inhibition and enhancement take part in various diseases, making it a target for therapeutic treatments. Current methods come with limitations, therefore, novel agents are constantly being researched, with metal agents offering promising results. Various transition metals have already been investigated in-depth, with studies indicating both pro- and antiangiogenic properties, respectively. The transition metals are being applied in various formulations, such as nanoparticles, complexes, or scaffold materials. Albeit the increasing attention this field is receiving, there remain many unanswered questions, mostly regarding the molecular mechanisms behind the observed effects. Notably, approximately half of all the transition metals have not yet been investigated regarding potential angiogenic effects. Considering the promising results which have already been established, it should be of great interest to begin investigating the remaining elements whilst also further analyzing the established effects.

USP14 Regulates ATF2/PIK3CD Axis to Promote Microvascular Endothelial Cell Proliferation, Migration, and Angiogenesis in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the leading causes of blindness in diabetic patients. However, the pathogenesis of DR is complex, and no firm conclusions have been drawn so far. It has become a hot spot in ophthalmology research to deeply study the mechanism of DR pathological changes and find effective treatment options. Human retinal microvascular endothelial cells (HRMECs) were induced by high glucose (HG) to construct DR cell model. CCK-8 assay was used to detect the viability of HRMECs. Transwell assay was used to detect the migration ability of HRMECs. Tube formation assay was used to identify the tube formation ability of HRMECs. The expressions of USP14, ATF2 and PIK3CD were detected by Western blot analysis and qRT-PCR assay. Immunoprecipitation (IP) was used to ascertain the relationship of USP14 and ATF2. To explore the regulatory relationship between ATF2 and PIK3CD by dual-luciferase reporter gene assay and Chromatin immunoprecipitation (ChIP) assay. High glucose treatment promoted the proliferation, migration, and tube formation of HRMEC, and the expressions of USP14, ATF2 and PIK3CD were significantly up-regulated. USP14 or ATF2 knockdown inhibited HG-induced HRMECs proliferation, migration, and tube formation. USP14 regulated the expression of ATF2, and ATF2 promoted PIK3CD expression. PIK3CD overexpression attenuated the inhibitory effectiveness of USP14 knockdown on proliferation, migration and tube formation of DR cell model. Here, we revealed that USP14 regulated the ATF2/PIK3CD axis to promote proliferation, migration, and tube formation in HG-induced HRMECs.

Efficacy and safety of pan retinal photocoagulation combined with intravitreal anti-VEGF agents for high-risk proliferative diabetic retinopathy: A systematic review and meta-analysis

BACKGROUND

High-risk proliferative diabetic retinopathy (HR-PDR) is the advanced stage of diabetic retinopathy progression with poor prior treatment efficacy and high rates of blindness. This meta-analysis aims to compare the efficacy and safety of pan retinal photocoagulation (PRP) combined with intravitreal anti-vascular endothelial growth factor (aVEGF) (PRP + aVEGF) versus PRP monotherapy in HR-PDR patients.

METHODS

A thorough search was performed through PubMed, Web of Science, EMBASE, and the Cochran Library from inception to December 18, 2022. Outcome measures included change in central macular thickness, best-corrected visual acuity, fluorescein angiography, incidence of undergoing vitrectomy, and adverse events during the follow-up period.

RESULTS

Eight studies (6 randomized controlled trials and 2 retrospective studies) with 375 eyes were included in this meta-analysis. There were no obvious differences in the changes of best-corrected visual acuity and fluorescein angiography between the PRP + aVEGF and PRP monotherapy groups. However, PRP + aVEGF group had a significant reduction in the change of central macula thickness (standard mean deviations = -1.44, 95%CI = -2.55 to -0.32, P = .01) and the rate of undergoing vitrectomy (odds ratio = 0.20, 95%CI = 0.05-0.83, P = .01). Additionally, the risks of vitreous hemorrhage and other complications were not significantly different between the 2 groups.

CONCLUSION SUBSECTIONS

Our meta-analysis indicated that PRP + aVEGF might have potential benefits in the treatment of HR-PDR patients. However, given several limitations of this study, more research is needed to confirm our findings.

Effects of autophagy inhibitor 3-methyladenine on a diabetic mice model

AIM

To investigate the role of autophagy inhibitor 3-methyladenine (3-MA) on a diabetic mice model (DM) and the potential mechanism.

METHODS

Male C57BL/6J mice were randomly divided into a normal control group (NC group) and an DM group. DM were induced by multiple low-dose intraperitoneal injection of streptozotocin (STZ) 60 mg/kg·d for 5 consecutive days. DM mice were randomly subdivided into untreated group (DM group), 3-MA (10 mg/kg·d by gavage) treated group (DM+3-MA group) and chloroquine (CQ; 50 mg/kg by intraperitoneal injection) treated group (DM+CQ group). The fasting blood glucose (FBG) levels were recorded every week. At the end of experiment, retinal samples were collected. The expression levels of pro-apoptotic proteins cleaved caspase-3, cleaved poly ADP-ribose polymerase 1 (PARP1) and Bax, anti-apoptotic protein Bcl-2, fibrosis-associated proteins Fibronectin and type 1 collagen α1 chain (COL1A1), vascular endothelial growth factor (VEGF), inflammatory factors interleukin (IL)-1β and tumor necrosis factor (TNF)-α, as well as autophagy related proteins LC3, Beclin-1 and P62 were determined by Western blotting. The oxidative stress indicators 8-hydroxydeoxyguanosine (8-OHdG) and malondialdehyde (MDA) were detected by commercial kits.

RESULTS

Both 3-MA and CQ had short-term hypoglycemic effect on FBG and reduced the expression of VEGF and inflammatory factors IL-1β and TNF-α in DM mice. 3-MA also significantly alleviated oxidative stress indicators 8-OHdG and MDA, decreased the expression of fibrosis-related proteins Fibronectin and COL1A1, pro-apoptotic proteins cleaved caspase-3, cleaved PARP1, as well as the ratio of Bax/Bcl-2. CQ had no significant impact on the oxidative stress indicators, fibrosis, and apoptosis related proteins. The results of Western blotting for autophagy related proteins showed that the ratio of LC3 II/LC3 I and the expression of Beclin-1 in the retina of DM mice were decreased by 3-MA treatment, and the expression of P62 was further increased by CQ treatment.

CONCLUSION

3-MA has anti-apoptotic and anti-fibrotic effects on the retina of DM mice, and can attenuate retinal oxidative stress, VEGF expression and the production of inflammatory factors in the retina of DM mice. The underlying mechanism of the above effects of 3-MA may be related to its inhibition of early autophagy and hypoglycemic effect.

TNFAIP8 overexpression aggravates retinal pathophysiological features of diabetic retinopathy

Our previous research shown that tumor necrosis factor-alpha-induced protein 8 (TNFAIP8) is elevated in the plasma extracellular vesicles and vitreous humor in diabetic retinopathy (DR). TNFAIP8 also significantly increases the viability of human retinal microvascular endothelial cells (HRMECs) and promotes cell migration and tube formation in vitro. To comprehensively explore its role in DR, we investigated the effect of TNFAIP8 on DR development using an animal model in this study. A TNFAIP8-overexpressing adeno-associated virus (AAV) vector and streptozotocin-induced mouse model was used. The AAV-TNFAIP8 vector was injected into the mice intravitreally, and the effect was evaluated. The evaluation included analysis of retinal structure and function using electroretinography, optical coherence tomography, and histological assessment. The influence of TNFAIP8 on the avascular area, retinal leukostasis, and the expression levels of inflammatory factors was also determined. TNFAIP8 significantly decreased a/b-wave amplitude and retinal thickness in diabetic mice. Histological assessment showed that TNFAIP8 aggravated pathological abnormalities with distorted organization of the retina. TNFAIP8 also significantly increased the avascular area, leukostasis, and the expression of inflammatory factors, such as TNFα, IL1β, ICAM1, and GFAP, in the retina. The results of this study support the role of TNFAIP8 in DR pathogenesis. A mechanistic understanding of TNFAIP8 may offer novel therapeutic strategies.

ADAMTS5 promotes neovascularization via autophagic degradation of PEDF in proliferative diabetic retinopathy

Proliferative diabetic retinopathy (PDR) adversely affects visual function. Extracellular matrix proteins (ECM) contribute significantly to the development of PDR. A Disintegrin and Metalloproteinase with Thrombospondin motifs 5 (ADAMTS5) is a member of ECM proteins. ADAMTS5 participates in angiogenesis and inflammation in diverse diseases. However, the role of ADAMTS5 in PDR remains elusive. Multiplex beam array technology was used to analyze vitreous humor of PDR patients and normal people. ELISA and Western blot were used to detect the expression of ADAMTS5, PEDF and autophagy related factors. Immunofluorescence assay was used to mark the expression and localization of ADAMTS5 and PEDF. The neovascularization was detected by tube formation test. Our results revealed that ADAMTS5 expression was increased in the vitreous humor of PDR patients and oxygen-induced retinopathy (OIR) mice retinas. Inhibiting ADAMTS5 alleviated pathological angiogenesis and upregulated PEDF expression in the OIR mice. In addition, ADAMTS5 inhibited PEDF secretion in ARPE-19 cells in vitro studies, thereby inhibiting the migration of HMEC-1. Mechanically, ADAMTS5 promoted the autophagic degradation of PEDF. Collectively, inhibition of ADAMTS5 during OIR suppresses pathological angiogenesis. Our study provides a new approach for resolving pathological angiogenesis in PDR.

Comparison of widefield swept-source optical coherence tomographic angiography and fluorescein fundus angiography for detection of retinal neovascularization with diabetic retinopathy

BACKGROUND

To compare vitreous angiomosaic images (VAMIs), obtained by widefield swept-source optical coherence tomographic angiography (wfSS-OCTA) and the image of fluorescein fundus angiography (FFA) in the identification of retinal neovascularization (NV) in patients with diabetic retinopathy (DR).

METHODS

In this prospective observational study, severe non-proliferative diabetic retinopathy (NPDR) or proliferative DR (PDR) patients were included. All patients underwent FFA and wfSS-OCTA. The number of NVs identified by wfSS-OCTA VAMIs using five fixations 12 × 12 mm montage scans and the resembling FFA images were compared.

RESULTS

Fifty-three eyes of 29 patients were enrolled. NVs were detected in 25 eyes by using FFA, including 9 NVs of the disc (NVDs) and 72 NVs elsewhere (NVEs), and in 29 eyes by OCTA, including 11 NVDs and 90 NVEs. The detection rate of NV and NVD of OCTA was comparable to that of FFA (p > 0.05), and the level of agreement was excellent (κ = 0.850, κ = 0.754). Using FFA as the gold standard, the sensitivity for detection of NV by OCTA was 100.0%, specificity was 85.7%, the positive-predictive value was 86.2%, and the negative-predictive value was 100.0%. Compared with FFA, OCTA was superior in terms of the number of NVEs identified (p = 0.024). When we excluded images of patients treated with anti-vascular endothelial growth factor (VEGF) intravitreal therapy for < 3 months, OCTA was comparable to FFA in terms of the number of NVEs discovered (p = 0.203), with excellent agreement (intraclass correlation coefficient = 0.941).

CONCLUSIONS

WfSS-OCTA is an independent non-invasive alternative to FFA for NV discovery, NVD detection, and individual NVE identification, particularly in patients with PDR who have a history of prior treatment with anti-VEGF.

Vison transformer adapter-based hyperbolic embeddings for multi-lesion segmentation in diabetic retinopathy

Diabetic Retinopathy (DR) is a major cause of blindness worldwide. Early detection and treatment are crucial to prevent vision loss, making accurate and timely diagnosis critical. Deep learning technology has shown promise in the automated diagnosis of DR, and in particular, multi-lesion segmentation tasks. In this paper, we propose a novel Transformer-based model for DR segmentation that incorporates hyperbolic embeddings and a spatial prior module. The proposed model is primarily built on a traditional Vision Transformer encoder and further enhanced by incorporating a spatial prior module for image convolution and feature continuity, followed by feature interaction processing using the spatial feature injector and extractor. Hyperbolic embeddings are used to classify feature matrices from the model at the pixel level. We evaluated the proposed model's performance on the publicly available datasets and compared it with other widely used DR segmentation models. The results show that our model outperforms these widely used DR segmentation models. The incorporation of hyperbolic embeddings and a spatial prior module into the Vision Transformer-based model significantly improves the accuracy of DR segmentation. The hyperbolic embeddings enable us to better capture the underlying geometric structure of the feature matrices, which is important for accurate segmentation. The spatial prior module improves the continuity of the features and helps to better distinguish between lesions and normal tissues. Overall, our proposed model has potential for clinical use in automated DR diagnosis, improving accuracy and speed of diagnosis. Our study shows that the integration of hyperbolic embeddings and a spatial prior module with a Vision Transformer-based model improves the performance of DR segmentation models. Future research can explore the application of our model to other medical imaging tasks, as well as further optimization and validation in real-world clinical settings.

Preclinical modeling of intravitreal suspensions

There are a number of obstacles that complicate the development of intravitreal delivered small molecules therapies. One serious complication is the potential need for complex polymer depot formulations early in the drug discovery process. The development of such formulations often requires substantial investment of time and material which may not be readily available in preclinical development. Herein I present a diffusion limited pseudo-steady state model to provide prediction of drug release from an intravitreally administered suspension formulation. By using such a model, a preclinical formulator may be able to more confidently determine if development of a complex formulation is required or if a simple suspension may work to support a study design. In this report, the model is used to predict the intravitreal preformance of two different molecules (triamcinolone acetonide and GNE-947) at multiple dose levels in rabbit eyes as well as provide a prediction for the performance of a marketed formulation of Trimacinolone Acetonide in humans.

Outcomes of 35-year duration of type 1 diabetes and proliferative diabetic retinopathy on functional vision and quality of life: Benefits of good glycemic control

AIMS

To evaluate clinical outcomes, functional vision and quality of life (QoL) after 35-year duration of type 1 diabetes (T1D) and proliferative diabetic retinopathy (PDR).

METHODS

A population-based cohort study of T1D. Data from laboratory tests, ophthalmic examinations, multifunctional vision-test, and 15D-QoL measurements were analysed.

RESULTS

35 % of the original cohort (n = 216) had PDR, and 48 % of them were re-evaluated. They were 41 ± 3 [34-46] years old and 62 % were males. The duration of T1D was 35 ± 4 [29-41] years. 76 % had transdermal glucose monitoring. HbA1c had decreased from 80.1 mmol/mol to 63.6 mmol/mol (p < 0.001). Visual acuity was 73-77 ETDRS-letters. Two patients had visual impairment. Visual field sensitivities were lower in PDR vs. healthy controls (23.2 ± 3.9 dB vs. 26.9 ± 1.0 dB, and 14.9 ± 5.6 dB vs. 21.0 ± 2.0 dB, respectively, p < 0.001). Contrast sensitivity was similar, but the reaction time was longer in the PDR group (490.5 ms vs. 462.8 ms, p = 0.004). QoL-parameters concerning sleeping, usual activities, discomfort and symptoms, and sexual activity had decreased, but improved for mobility and distress.

CONCLUSIONS

Long-term visual prognosis and QoL remained good despite the declined functional vision caused by PDR.

Fluorescence Angiography with Dual Fluorescence for the Early Detection and Longitudinal Quantitation of Vascular Leakage in Retinopathy

BACKGROUND

Diabetic retinopathy (DR) afflicts more than 93 million people worldwide and is a leading cause of vision loss in working adults. While DR therapies are available, early DR development may go undetected without treatment due to the lack of sufficiently sensitive tools. Therefore, early detection is critically important to enable efficient treatment before progression to vision-threatening complications. A major clinical manifestation of early DR is retinal vascular leakage that may progress from diffuse to more localized focal leakage, leading to increased retinal thickness and diabetic macular edema (DME). In preclinical research, a hallmark of DR in mouse models is diffuse retinal leakage without increased thickness or DME, which limits the utility of optical coherence tomography and fluorescein angiography (FA) for early detection. The Evans blue assay detects diffuse leakage but requires euthanasia, which precludes longitudinal studies in the same animals.

METHODS

We developed a new modality of ratiometric fluorescence angiography with dual fluorescence (FA-DF) to reliably detect and longitudinally quantify diffuse retinal vascular leakage in mouse models of induced and spontaneous DR.

RESULTS

These studies demonstrated the feasibility and sensitivity of FA-DF in detecting and quantifying retinal vascular leakage in the same mice over time during DR progression in association with chronic hyperglycemia and age.

CONCLUSIONS

These proof-of-concept studies demonstrated the promise of FA-DF as a minimally invasive method to quantify DR leakage in preclinical mouse models longitudinally.

Proteomics profiling of vitreous humor reveals complement and coagulation components, adhesion factors, and neurodegeneration markers as discriminatory biomarkers of vitreoretinal eye diseases

Introduction

Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are leading causes of visual impairment and blindness in people aged 50 years or older in middle-income and industrialized countries. Anti-VEGF therapies have improved the management of neovascular AMD (nAMD) and proliferative DR (PDR), no treatment options exist for the highly prevalent dry form of AMD.

Methods

To unravel the biological processes underlying these pathologies and to find new potential biomarkers, a label-free quantitative (LFQ) method was applied to analyze the vitreous proteome in PDR (n=4), AMD (n=4) compared to idiopathic epiretinal membranes (ERM) (n=4).

Results and discussion

Post-hoc tests revealed 96 proteins capable of differentiating among the different groups, whereas 118 proteins were found differentially regulated in PDR compared to ERM and 95 proteins in PDR compared to dry AMD. Pathway analysis indicates that mediators of complement, coagulation cascades and acute phase responses are enriched in PDR vitreous, whilst proteins highly correlated to the extracellular matrix (ECM) organization, platelet degranulation, lysosomal degradation, cell adhesion, and central nervous system development were found underexpressed. According to these results, 35 proteins were selected and monitored by MRM (multiple reaction monitoring) in a larger cohort of patients with ERM (n=21), DR/PDR (n=20), AMD (n=11), and retinal detachment (n=13). Of these, 26 proteins could differentiate between these vitreoretinal diseases. Based on Partial least squares discriminant and multivariate exploratory receiver operating characteristic (ROC) analyses, a panel of 15 discriminatory biomarkers was defined, which includes complement and coagulation components (complement C2 and prothrombin), acute-phase mediators (alpha-1-antichymotrypsin), adhesion molecules (e.g., myocilin, galectin-3-binding protein), ECM components (opticin), and neurodegeneration biomarkers (beta-amyloid, amyloid-like protein 2).

Vitreous humor proteome: unraveling the molecular mechanisms underlying proliferative and neovascular vitreoretinal diseases

Proliferative diabetic retinopathy (PDR), proliferative vitreoretinopathy (PVR), and neovascular age-related macular degeneration (nAMD) are among the leading causes of blindness. Due to the multifactorial nature of these vitreoretinal diseases, omics approaches are essential for a deeper understanding of the pathophysiologic processes underlying the evolution to a proliferative or neovascular etiology, in which patients suffer from an abrupt loss of vision. For many years, it was thought that the function of the vitreous was merely structural, supporting and protecting the surrounding ocular tissues. Proteomics studies proved that vitreous is more complex and biologically active than initially thought, and its changes reflect the physiological and pathological state of the eye. The vitreous is the scenario of a complex interplay between inflammation, fibrosis, oxidative stress, neurodegeneration, and extracellular matrix remodeling. Vitreous proteome not only reflects the pathological events that occur in the retina, but the changes in the vitreous itself play a central role in the onset and progression of vitreoretinal diseases. Therefore, this review offers an overview of the studies on the vitreous proteome that could help to elucidate some of the pathological mechanisms underlying proliferative and/or neovascular vitreoretinal diseases and to find new potential pharmaceutical targets.

Integrated Analysis of Metabolomics and Lipidomics in Plasma of T2DM Patients with Diabetic Retinopathy

Diabetic retinopathy (DR) is a major cause of blindness worldwide and may be non-proliferative (NPDR) or proliferative (PDR). To Investig.gate the metabolomic and lipidomic characteristics of plasma in DR patients, plasma samples were collected from patients with type 2 diabetes mellitus (DR group) with PDR (n = 27), NPDR (n = 18), or no retinopathy (controls, n = 21). Levels of 54 and 41 metabolites were significantly altered in the plasma of DR patients under positive and negative ion modes, respectively. By subgroup analysis, 74 and 29 significantly changed plasma metabolites were detected in PDR patients compared with NPDR patients under positive and negative ion modes, respectively. KEGG analysis indicated that pathways such as biosynthesis of amino acids and neuroactive ligand-receptor interaction were among the most enriched pathways in altered metabolites in the DR group and PDR subgroup. Moreover, a total of 26 and 41 lipids were significantly changed in the DR group and the PDR subgroup, respectively. The panel using the 29-item index could discriminate effectively between diabetic patients with and without retinopathy, and the panel of 22 items showed effective discrimination between PDR and NPDR. These results provide a basis for further research into the therapeutic targets associated with these metabolite and lipid alterations.

Selective Activation of the Wnt-Signaling Pathway as a Novel Therapy for the Treatment of Diabetic Retinopathy and Other Retinal Vascular Diseases

Retinal ischemia, often associated with various disorders such as diabetic retinopathy (DR), retinal vein occlusion, glaucoma, optic neuropathies, stroke, and other retinopathies, is a major cause of visual impairment and blindness worldwide. As proper blood supply to the retina is critical to maintain its high metabolic demand, any impediment to blood flow can lead to a decrease in oxygen supply, resulting in retinal ischemia. In the pathogenesis of DR, including diabetic macular edema (DME), elevated blood glucose leads to blood-retina barrier (BRB) disruptions, vascular leakage, and capillary occlusion and dropouts, causing insufficient delivery of oxygen to the retina, and ultimately resulting in visual impairment. Other potential causes of DR include neuronal dysfunction in the absence of vascular defect, genetic, and environmental factors. The exact disease progression remains unclear and varies from patient to patient. Vascular leakage leading to edema clearly links to visual impairment and remains an important target for therapy. Despite recent advances in the treatment of DME and DR with anti-VEGFs, effective therapies with new mechanisms of action to address current treatment limitations regarding vessel regeneration and reperfusion of ischemic retinal areas are still needed. The Wnt signaling pathway plays a critical role in proper vascular development and maintenance in the retina, and thus provides a novel therapeutic approach for the treatment of diabetic and other retinopathies. In this review, we summarize the potential of this pathway to address treatment gaps with current therapies, its promise as a novel and potentially disease modifying therapy for patients with DR and opportunities in other retinal vascular diseases.

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

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

Progress and Challenges of Anti-VEGF Agents and Their Sustained-Release Strategies for Retinal Angiogenesis

Currently, the treatment for ocular neovascular diseases, including diabetic macular edema (DME) and age-related macular degeneration (AMD), mainly involves repeated intravitreal injection of anti-vascular endothelial growth factor (VEGF) drugs. Although it can preserve vision, repeated injections are an invasive treatment modality, leading to serious complications and reducing patient adherence to treatment. To reduce the frequency of administration, prolong the time of drug action, and avoid repeated intravitreal injections, the combination of sustained-release materials with anti-VEGF drug therapy has become an emphasis in ophthalmology. In this review, we highlight the current state of anti-VEGF technology, its challenges, and the sustained-release strategies under investigation or being used in clinical practice. Both continuous release and considerable therapeutic effects can be achieved by encapsulating anti-VEGF drugs in sustained-release materials to minimize the number of intravitreal injections. At present, two sustained-release materials are being tested in clinical research, and although basic research shows the strong therapeutic application prospects of extended-release drugs, its challenges mainly involve the discrepancy between the release rates in vitro and the efficiency of the drugs in vivo. Briefly, sustained release of anti-VEGF agents is an advantageous strategy for treating retinal angiogenesis.

New Insights into Treating Early and Advanced Stage Diabetic Retinopathy

Diabetic retinopathy (DR) is the leading cause of preventable blindness in the working-age population. The disease progresses slowly, and we can roughly differentiate two stages: early-stage (ESDR), in which there are mild retinal lesions and visual acuity is generally preserved, and advanced-stage (ASDR), in which the structural lesions are significant and visual acuity is compromised. At present, there are no specific treatments for ESDR and the current recommended action is to optimize metabolic control and maintain close control of blood pressure. However, in the coming years, it is foreseeable that therapeutic strategies based in neuroprotection will be introduced in the clinical arena. This means that screening aimed at identifying patients in whom neuroprotective treatment might be beneficial will be crucial. Regarding the treatment of ASDR, the current primary course is based on laser photocoagulation and intravitreal injections of anti-angiogenic factors or corticosteroids. Repeated intravitreal injections of anti-VEGF agents as the first-line treatment would be replaced by more cost-effective and personalized treatments based on the results of “liquid biopsies” of aqueous humor. Finally, topical administration (i.e., eye drops) of neuroprotective, anti-inflammatory and anti-angiogenic agents will represent a revolution in the treatment of DR in the coming decade. In this article, all these approaches and others will be critically discussed from a holistic perspective.