Systemic and Ocular Adverse Events with Intravitreal Anti-VEGF Therapy Used in the Treatment of Diabetic Retinopathy: a Review

Evaluating anti-VEGF responses in diabetic macular edema: A systematic review with AI-powered treatment insights

Recent advances in deep learning and machine learning have greatly increased the capabilities of extracting features for evaluating the response to anti VEGF treatment in patients with Diabetic Macular Edema (DME). In this review, we explore how these algorithms can be used for discriminating between responders and non-responders to anti vascular endothelial growth factor (VEGF) injections. Electronic databases, including PubMed, IEEE Xplore, BioMed, JAMA, and Google Scholar, were searched, and reference lists from relevant publications were also considered from inception till August 31, 2023, based on the inclusion and exclusion criteria. Data extraction was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The results focus on keywords such as DME, OCT, anti VEGF, and patient responses after anti VEGF injections. The article measures the effectiveness of different machine learning and deep learning algorithms, including linear discriminant analysis (LDA), ResNet-50, CNN with attention, quadratic discriminant analysis (QDA), random forest (RF), and support vector machines (SVM), in analyzing eyes that could tolerate extended interval dosing. According to a review of 50 relevant papers published between 2016 and 2023, the algorithms achieved an average automated sensitivity of 74% (95% CI: 0.55-0.92) in detecting treatment responses.

Revolutionizing drug delivery strategies with probucol to combat oxidative stress in retinal degeneration: A comprehensive review

Localized oxidative stress plays a key role in the development of retinal degenerative diseases, with diabetic retinopathy (DR) being one of them, contributing significantly to this vision-threatening complication of diabetes. Increased oxidative burden leads to dysfunction across various retinal cell types, including vascular endothelial cells, neurons, glial cells and pericytes. Importantly, even after achieving normalized glycemia, the detrimental effects of oxidative stress persist. Nonetheless, growing data highlights the therapeutic potential of antioxidants in safeguarding vision. However, extensive clinical trials using traditional antioxidants have produced mixed results. Therefore, probucol, known for its ability to limit vascular oxidative stress, decrease superoxide generation, and improve endogenous antioxidant activity, is a promising candidate explored in this review. In addition to describing probucol, this review will explore novel therapeutic formulation strategies by incorporating bile acid into probucol-loaded nanoparticles to enhance drug delivery to the posterior segment of the eye for more effective management of DR. The integration of bio-nanotechnology with probucol and bile acids represents a promising avenue for developing effective therapies for DR, addressing the limitations of traditional antioxidant treatments.

Uncovering the potential mechanism and bioactive compounds of Salviae Miltiorrhizae Radix et Rhizoma in attenuating diabetic retinopathy

BACKGROUND

Diabetic retinopathy (DR) is a serious microangiopathy resulting from diabetes. Salviae Miltiorrhizae Radix et Rhizoma (Danshen) is commonly used to treat cardiovascular diseases in clinics in China. However, whether it can also be used for DR treatment, along with its primary active compounds and underlying mechanisms of action, remains unclear.

PURPOSE

To evaluate the alleviation of water extract of Salvia miltiorrhiza Radix et Rhizoma (SWE) on DR, elucidate the underlying mechanisms, and identify the primary active compounds.

METHODS

Mice were intraperitoneally injected with streptozotocin (STZ) to induce diabetes. Blood-retina barrier (BRB) breakdown was detected. The potential underlying mechanisms were predicted by network pharmacology and further validated by Western blot, leukostasis assay and real-time polymerase chain reaction (PCR). The primary active compounds in SWE were identified by integrating in vitro activity analysis and molecular docking.

RESULTS

SWE attenuated BRB breakdown in STZ-induced DR mice. Results of network pharmacology and further experimental validation implied that inhibiting retinal inflammation and angiogenesis, and reversing endothelial barrier dysfunction were involved in the SWE-provided alleviation of DR, and the key involved signaling pathways were PI3K-AKT, VEGF, TNF, and NFκB pathways. Further results in vitro demonstrated that salvianolic acid A (SalA), salvianolic acid B (SalB), salvianolic acid C (SalC), and Tanshinone IIA (TanIIA) not only reduced the expression of pro-inflammatory cytokines but also inhibited the adhesion of inflammatory cells. However, danshensu (DSS), cryptotanshinone (CTS), and tanshinone I (TanI) only downregulated the expression of pro-inflammatory cytokines. SalA, SalB, and CTS reversed endothelial barrier dysfunction in vitro. SalA, SalB, SalC, CTS, DSS, and TanIIA decreased VEGF mRNA expression, and TanIIA also inhibited VEGF-induced angiogenesis in vitro. Molecular docking predicted potential interactions between these active compounds and several key molecules involved in regulating inflammation, angiogenesis, and cell-cell junctions. These compounds abrogated hyperglycemia-induced phosphorylation of AKT1 and PI3 K in vitro. Furthermore, the interactions of SalA, SalB, SalC, and TanIIA with TNFR1 were further validated using cellular thermal shift assay (CETSA).

CONCLUSION

SWE alleviated DR via reversing BRB breakdown and suppressing retinal inflammation and angiogenesis. SalA, SalB, SalC, TanIIA, and CTS might be primary active compounds in SWE, and they contributed greatly to the improvement of SWE against DR via reversing endothelial barrier injury, inhibiting inflammation and angiogenesis.

Pharmacovigilance in intraocular antiangiogenic therapy

INTRODUCTION/OBJECTIVE

Anti-VEGF (Vascular endothelial growth factor) agents have revolutionized ophthalmotherapy and are vital for various retinal disease treatment in ophthalmic practice. Ophthalmology has witnessed an explosion in the number of intravitreal injections delivered to patients over the past years. The rising popularity of anti-VEGF drugs came along with concerns about its safety in clinical use. The aim of this focused review is to critically analyze currently available findings on systemic safety.

MATERIALS AND METHODS

A literature search was conducted using PubMed, Web of Science, and Google Scholar databases for studies published from January 2012 to February 2025. The reference lists of meta-analyses and selected studies were also reviewed. Eighty four articles of high or medium clinical relevance were selected for review. The exclusion criteria included non-English language publications, articles directly unrelated to the review topic, commentaries, conference abstracts.

RESULTS

Systemic safety concern in intraocular pharmacotherapy by antiangiogenic agents has a strong body of clinical evidence, resulting in plenty of peer reviewed clinical articles. It is certainly becoming recognized that anti-VEGF agents, despite given intraocularly, have the potential to cause systemic adverse events, such as cardiovascular, renal, neurological.

CONCLUSIONS

Accumulating evidence obviate the need to raise medical professionals' awareness about systemic risk profile in patients with eye diseases treated by anti-VEGF, paying a special attention on patients with diabetes and older patients with multimorbidity. Early identification and prompt management of patients with undesirable systemic side effects secondary to intraocular pharmacotherapy by angiogenics can lessen disease severity, and help achieve earlier resolution.

Efficacy and Safety of Efdamrofusp Alfa versus Aflibercept in Participants with Neovascular Age-Related Macular Degeneration: A Randomized, Double-Masked, Active-Controlled, Noninferiority, Phase II Trial

PURPOSE

To evaluate efficacy and safety of efdamrofusp alfa compared with aflibercept in neovascular age-related macular degeneration (nAMD).

DESIGN

Randomized, double-masked, multicenter, active-controlled, noninferiority phase II study.

PARTICIPANTS

A total of 231 treatment-naive and previously treated participants with active choroidal neovascularization secondary to nAMD were enrolled.

METHODS

Eligible participants were randomized (1:1:1) to 2 mg efdamrofusp alfa, 4 mg efdamrofusp alfa, or 2 mg aflibercept groups. Participants in all groups received 3 initial monthly loading doses, followed by treatment every 8 weeks, with assessment every 4 weeks up to week 52.

MAIN OUTCOME MEASURES

The primary end point was the mean best-corrected visual acuity (BCVA) change from baseline to week 36. The prespecified noninferiority margin was set as -5 letters (80% confidence interval [CI]).

RESULTS

Each treatment group included 77 participants. The mean BCVA changes from baseline to week 36 for 2 mg efdamrofusp alfa, 4 mg efdamrofusp alfa and aflibercept groups were +10.6, +11.4, and +12.0 letters, respectively; least squares mean difference were -1.4 (80% CI: -3.5 to 0.7) between 2 mg efdamrofusp alfa and aflibercept, and -0.6 (80% CI: -2.7 to 1.6) between 4 mg efdamrofusp alfa and aflibercept. Mean central retinal thickness changes were consistent across groups. Adverse event rate was comparable among the groups.

CONCLUSIONS

Efdamrofusp alfa demonstrated noninferiority to aflibercept in BCVA improvement, accompanied by a similar safety profile.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Anti-Syndecan 2 Antibody Treatment Reduces Edema Formation and Inflammation of Murine Laser-Induced CNV

Purpose

Alteration of visual acuity in wet age-related macular degeneration (AMD) is mostly driven by vascular endothelial growth factor A (VEGF-A)-induced edema from leaky newly forming blood vessels below the retina layers. To date, all therapies aimed at alleviation of this process have relied on inhibition of VEGF-A activity. Although effective in preventing vascular leak and edema, this approach also leads to the loss of normal vasculature and multiple related side effects.

Methods

We have developed an alternative strategy that uses anti-syndecan-2 polyclonal antibody (anti-Sdc2 pAb) to block VEGF-A-induced permeability without interfering with other VEGF-A activities. The effect of anti-Sdc2 pAb therapy was assessed in vitro using a transendothelial electrical resistance (TEER) assay, as well as staining of the endothelial cell junction, and in vivo in the laser-induced choroidal neovascularization (CNV) model.

Results

Anti-Sdc2 pAb blocked VEGF-A-induced permeability in vitro, and both local intravitreal injections and systemic intravenous treatments with anti-Sdc2 pAb were as effective as intravitreal anti-VEGF therapy in reducing edema, size of retinal lesions, and local inflammation in this model. Post-injury neovascularization was not affected by treatment with anti-Sdc2 pAb.

Conclusions

These findings indicate that anti-Sdc2 pAb therapy can be an effective alternative to anti-VEGF-A approaches for suppression of edema and to prevent retinal lesions in wet neovascular AMD (nAMD).

Translational Relevance

Intravitreal anti-Sdc2 treatment may avoid side effects observed with the long-term anti-VEGF therapy, and systemic treatment with an anti-Sdc2 pAb antibody can address the issues associated with repeated intravitreal injections.

Repeated treatment with VEGF receptor inhibitors induces phenotypic changes in endothelial cells and pericytes in the rat retina

Abnormal ocular angiogenesis is a major cause of visual impairment and vision loss in neovascularization-related diseases. Currently, anti-vascular endothelial growth factor (VEGF) drugs are used to treat ocular neovascularization, but repeated injections are needed to maintain their therapeutic effects. However, repeated injection of anti-VEGF drugs may affect the retinal blood vessel phenotype and diminish therapeutic effects. In this study, we aimed to investigate the phenotypic changes in endothelial cells and pericytes caused by the repeated interruption of the VEGF receptor signaling pathway in neonatal rats. KRN633 (10 mg/kg), a VEGF receptor tyrosine kinase inhibitor, was subcutaneously administered on postnatal day (P)-7 and P8 (first round), P14 and P15 (second round), and P21 and P22 (third round). The rat eyes were collected on P7, P9, P14, P16, P21, P23, P28, and P35. Using retinal flat-mount specimens stained with specific markers for vascular endothelial cells, basement membranes, and pericytes, the arteriolar tortuosity, capillary area density, and distribution of pericytes were evaluated. Significant loss of capillaries was observed the day after the first round of KRN633 treatment, after which aggressive angiogenesis occurred, leading to the formation of tortuous arterioles. Rats that completed second and third rounds of KRN633 treatment showed more severe abnormalities in the retinal vasculature than those that only completed first round treatment. Repeated treatment with KRN633 decreased the anti-angiogenic effects but increased the immunoreactivity of α-smooth muscle actin in the pericytes on veins and capillaries. α-Smooth muscle actin expression was inversely correlated to anti-angiogenic effects. Overall, these results revealed that repeated interruption of VEGF receptor signaling pathway altered the phenotypes of endothelial cells and pericytes and induced anti-VEGF drug resistance. Therefore, careful follow-up is necessary when using anti-VEGF drugs to treat abnormal angiogenesis-associated ocular diseases.

Subconjunctival Administration of an Adeno-Associated Virus Expressing Stanniocalcin-1 Provides Sustained Intraocular Pressure Reduction in Mice

Purpose

To investigate subconjunctival administration of a single-stranded, adeno-associated virus, serotype 2, engineered to express stanniocalcin-1 with a FLAG tag (ssAAV2-STC-1-FLAG) as a novel sustained (IOP) lowering agent with a reduced ocular surface side effect profile.

Design

In vivo preclinical investigation in mice.

Subjects

C57BL/6J, DBA/2J, prostaglandin F (FP) receptor knockout mice.

Methods

Normotensive C57BL/6J mice were treated with a subconjunctival injection of ssAAV2-STC-1-FLAG (2 μL; 6 × 109 viral genomes [VGs]) in 1 eye and the same volume and concentration of ssAAV2-green fluorescent protein (GFP) or the same volume of phosphate-buffered saline in the fellow eye. Ocular hypertensive DBA/2J mice were subconjunctivally injected with 6 × 109 VGs of ssAAV2-STC-1-FLAG or ssAAV2-GFP. Steroid-mediated ocular hypertension was induced in C57BL/6J mice with weekly injections of dexamethasone into the conjunctival fornix, and mice were then injected subconjunctivally with 6 × 109 VGs of ssAAV2-STC-1-FLAG or ssAAV2-GFP. Prostaglandin F receptor knockout mice were injected subconjunctivally with 6 × 109 VGs of ssAAV2-STC-1-FLAG or phosphate-buffered saline. An identical vector was constructed without the FLAG tag (ssAAV2-STC-1) and evaluated in normotensive C57BL/6J mice. Intraocular pressure was assessed using the Tonolab tonometer for all experiments. Tumor necrosis factor alpha (TNFα), a marker of ocular surface inflammation, was compared between subconjunctivally delivered ssAAV2-STC-1-FLAG and other treatments including daily topical latanoprost.

Main Outcome Measures

Intraocular pressure assessment.

Results

Subconjunctival delivery of ssAAV2-STC-1-FLAG significantly reduced IOP for 10 weeks post injection in normotensive mice. Maximal IOP reduction was seen at week 3 postinjection (17.4%; 17.1 ± 0.8 vs. 14.1 ± 0.8 mmHg, P < 0.001). After the IOP-lowering effect had waned, a second injection restored the ocular hypotensive effect. Subconjunctivally delivered ssAAV2-STC-1-FLAG lowered IOP in DBA/2J mice (16.9%; 17.8 ± 2.0 vs. 14.8 ± 0.9 mmHg, P < 0.001) and steroid-mediated ocular hypertensive mice (20.0%; 19.0 ± 0.6 vs. 15.2 ± 0.7 mmHg, P < 0.001) over the experimental period. This construct also reduced IOP to a similar extent in wild-type (15.9%) and FP receptor knockout (15.7%) mice compared with the fellow eye. A related construct also lowered IOP without the FLAG tag in a similar manner. Reduction in conjunctival TNFα was seen when comparing subconjunctivally delivered ssAAV2-STC-1-FLAG to daily topical latanoprost.

Conclusions

Subconjunctival delivery of the STC-1 transgene with a vector system may represent a novel treatment strategy for sustained IOP reduction and improved ocular tolerability that also avoids the daily dosing requirements of currently available medications.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Novel strategies in systemic and local administration of therapeutic monoclonal antibodies

Monoclonal antibodies (mAbs) are an evolving class of biopharmaceuticals, with advancements evident across various stages of their development. While discovery, mAb chemical optimization, production and purification processes have been thoroughly reviewed, this paper aims to offer a summary of novel strategies in administration of mAbs. At present, systemic delivery of mAbs is available through parenteral administration routes with focus on subcutaneous administration. In addition, oriented toward patient-friendly therapy, other less invasive administration routes of mAbs, such as inhalation, nasal, transdermal, and oral administration, are explored. Literature data reveals the potential for local delivery of mAbs via inhalation, nasal, transdermal, intratumoral, intravitreal and vaginal administration, offering high efficacy with fewer systemic adverse effects. However, to date, only mAb medicines are available for intravitreal administration, mainly due to higher bioavailability, and an intranasal spray is authorised as a medical device. The review highlights the promising data in approval of novel administration routes, likely through inhalation, but further intensive research considering the current obstacles, is essential.

Advanced drug delivery strategies for diabetic retinopathy: current therapeutic advancement, and delivery methods overcoming barriers, and experimental modalities

INTRODUCTION

Diabetic retinopathy, a significant trigger for blindness among working age individuals with diabetes, poses a substantial global health challenge. Understanding its underlying mechanisms is pivotal for developing effective treatments. Current treatment options, such as anti-VEGF agents, corticosteroids, laser photocoagulation, and vitreous surgery, have their limitations, prompting the exploration of innovative approaches like nanocapsules based drug-delivery systems. Nanoparticles provide promising solutions to improve drug delivery in ocular medicine, overcoming the complexities of ocular anatomy and existing treatment constraints.

AREAS COVERED

This review explored advanced therapeutic strategies for diabetic retinopathy, focusing on current medications with their limitations, drug delivery methods, device innovations, and overcoming associated barriers. Through comprehensive review, it aimed to contribute to the discovery of more efficient management strategies for diabetic retinopathy in the future.

EXPERT OPINION

In the next five to ten years, we expect a revolutionary shift in how diabetic retinopathy is treated. As we deepen our understanding of oxidative stress and metabolic dysfunction, antioxidants with specialised delivery matrices are poised to take center stage in prevention and treatment strategies. Our vision is to create a more integrated approach to diabetic retinopathy management that not only improves patient outcomes but also reduces the risks associated to traditional therapies.

Anti-Vascular Endothelial Growth Factor Combined with Ocular Steroid Therapy for Persistent Diabetic Macular Edema: A Systematic Review and Meta-Analysis

Purpose: Our purpose was to appraise the efficacy and safety of intravitreous vascular endothelial growth factor inhibitor (anti-VEGF) therapy combined with steroids for persistent diabetic macular edema. Methods: A systematic review was conducted of the research evaluating the combination therapy of anti-VEGF and steroids for persistent diabetic macular edema compared to anti-VEGF alone. A meta-analysis was performed using a protocol registered in PROSPERO (CRD42023476333). Continuous and binary variables were extracted. Results were expressed as the mean difference (MD) and risk ratio (RR). Results: A total of 9 trials with 537 eyes were included. The MDs of improvement in best-corrected visual acuity (BCVA) at 1/2/3/6/9/12 months between the combined and monotherapy groups were 1.33 (95% CI [-1.31,3.96]), 3.03 (95% CI [0.01, 6.06]), -0.37 (95% CI [-4.74, 4.00]), -1.37 (95% CI [-4.65, 1.91]), 1.05 (95% CI [-3.68, 5.77]), and 1.70 (95% CI [-3.52, 6.93]). The MDs concerned with a central retinal thickness (CMT) decline in at 1/2/3/6/9/12 months between the two groups were -47.33, 95% CI [-94.35, -0.32]), -89.19 (95% CI [-114.38, -64.00]), -58.84 (95% CI [-96.93, -20.74]), -57.23 (95% CI [-102.62, -11.84]), -40.59 (95% CI [-80.59, -0.58]), and -38.89 (95% CI [-77.38, -0.40]), respectively. Furthermore, the combined group obtained higher relative risks of experiencing events with high intraocular pressure and progressed cataracts. Conclusions: Anti-VEGF combined with ocular steroids showed a significant advantage in improving the retinal anatomical structure compared to anti-VEGF monotherapy for persistent diabetic macular edema. However, as the treatment period extended, the combination treatment was no more effective than monotherapy after 2 months, with more severe side effects.

Timed topical dexamethasone eye drops improve mitochondrial function to prevent severe retinopathy of prematurity

Pathological neovascularization in retinopathy of prematurity (ROP) can cause visual impairment in preterm infants. Current ROP treatments which are not preventative and only address late neovascular ROP, are costly and can lead to severe complications. We showed that topical 0.1% dexamethasone eye drops administered prior to peak neovessel formation prevented neovascularization in five extremely preterm infants at high risk for ROP and suppressed neovascularization by 30% in mouse oxygen-induced retinopathy (OIR) modeling ROP. In contrast, in OIR, topical dexamethasone treatment before any neovessel formation had limited efficacy in preventing later neovascularization, while treatment after peak neovessel formation had a non-statistically significant trend to exacerbating disease. Optimally timed topical dexamethasone suppression of neovascularization in OIR was associated with increased retinal mitochondrial gene expression and decreased inflammatory marker expression, predominantly found in immune cells. Blocking mitochondrial ATP synthetase reversed the inhibitory effect of dexamethasone on neovascularization in OIR. This study provides new insights into topical steroid effects in retinal neovascularization and into mitochondrial function in phase II ROP, and suggests a simple clinical approach to prevent severe ROP.

Mitochondrial control of hypoxia-induced pathological retinal angiogenesis

OBJECTIVE

Pathological retinal neovascularization is vision-threatening. In mouse oxygen-induced retinopathy (OIR) we sought to define mitochondrial respiration changes longitudinally during hyperoxia-induced vessel loss and hypoxia-induced neovascularization, and to test interventions addressing those changes to prevent neovascularization.

METHODS

OIR was induced in C57BL/6J mice and retinal vasculature was examined at maximum neovessel formation. We assessed total proteome changes and the ratio of mitochondrial to nuclear DNA copy numbers (mtDNA/nDNA) of OIR vs. control retinas, and mitochondrial oxygen consumption rates (OCR) in ex vivo OIR vs. control retinas (BaroFuse). Pyruvate vs. vehicle control was supplemented to OIR mice either prior to or during neovessel formation.

RESULTS

In OIR vs. control retinas, global proteomics showed decreased retinal mitochondrial respiration at peak neovascularization. OCR and mtDNA/nDNA were also decreased at peak neovascularization suggesting impaired mitochondrial respiration. In vivo pyruvate administration during but not prior to neovessel formation (in line with mitochondrial activity time course) suppressed NV.

CONCLUSIONS

Mitochondrial energetics were suppressed during retinal NV in OIR. Appropriately timed supplementation of pyruvate may be a novel approach in neovascular retinal diseases.

Corilagin alleviates ferroptosis in diabetic retinopathy by activating the Nrf2 signaling pathway

BACKGROUND AND PURPOSE

Diabetic retinopathy (DR) is a prevalent complication of diabetes, with a rising global incidence, and can result in significant vision impairment and potential blindness in adults. Corilagin (COR) has been shown to regulate several pathological processes. However, the specific protective role and mechanism of action of COR in DR remain unknown.

EXPERIMENTAL APPROACH

The protective effects and mechanisms of COR in DR were examined using the ARPE-19 cell line and C57BL/6 mice. Intraretinal tissue damage and molecular markers were evaluated to investigate the impact of COR on oxidative stress and cell death pathways.

KEY RESULTS

In vitro, COR significantly reduced the cytotoxic effects of high glucose (HG) on ARPE-19 cells. Furthermore, COR also effectively decreased HG-induced lipid peroxidation, iron deposition, and ferroptosis and reduced damage to retinal tight junction proteins. Similarly, an in vivo study of streptozotocin (STZ)-induced DM mice showed that the daily gavage of COR for eight weeks notably alleviated DR. Mechanistically, COR activated the Nrf2 antioxidant signaling pathway both in vivo and in vitro, preventing HG-induced alterations in morphological and biochemical parameters. Notably, our study demonstrated that compared with controls, Nrf2 knockout mice and siNrf2-treated cells were more vulnerable to ferroptosis under HG conditions, and the protective effect of COR on DR was substantially diminished in these models.

CONCLUSION AND IMPLICATIONS

These data indicate that COR has a protective effect against HG-induced retinal injury via a mechanism associated with the Nrf2-dependent antioxidant pathway and ferroptosis regulation.

Heme: A link between hemorrhage and retinopathy of prematurity progression

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

Enhanced Ocular Delivery of Beva via Ultra-Small Polymeric Micelles for Noninvasive Anti-VEGF Therapy

Pathological ocular neovascularization resulting from retinal ischemia constitutes a major cause of vision loss. Current anti-VEGF therapies rely on burdensome intravitreal injections of Bevacizumab (Beva). Herein ultrasmall polymeric micelles encapsulating Beva (P@Beva) are developed for noninvasive topical delivery to posterior eye tissues. Beva is efficiently loaded into 11 nm micelles fabricated via self-assembly of hyperbranched amphiphilic copolymers. The neutral, brush-like micelles demonstrate excellent drug encapsulation and colloidal stability. In vitro, P@Beva enhances intracellular delivery of Beva in ocular cells versus free drug. Ex vivo corneal and conjunctival-sclera-choroidal tissues transport after eye drops are improved 23-fold and 7.9-fold, respectively. Anti-angiogenic bioactivity is retained with P@Beva eliciting greater inhibition of endothelial tube formation and choroid sprouting over Beva alone. Remarkably, in an oxygen-induced retinopathy (OIR) model, topical P@Beva matching efficacy of intravitreal Beva injection, is the clinical standard. Comprehensive biocompatibility verifies safety. Overall, this pioneering protein delivery platform holds promise to shift paradigms from invasive intravitreal injections toward simplified, noninvasive administration of biotherapeutics targeting posterior eye diseases.

Timed topical dexamethasone eye drops improve mitochondrial function to prevent severe retinopathy of prematurity

Pathological neovascularization in retinopathy of prematurity (ROP) can cause visual impairment in preterm infants. Current ROP treatments which are not preventative and only address late neovascular ROP, are costly and can lead to severe complications. We showed that topical 0.1% dexamethasone eye drops administered prior to peak neovessel formation prevented neovascularization in five extremely preterm infants at high risk for ROP and suppressed neovascularization by 30% in mouse oxygen-induced retinopathy (OIR) modeling ROP. In contrast, in OIR, topical dexamethasone treatment before any neovessel formation had limited efficacy in preventing later neovascularization, while treatment after peak neovessel formation had a non-statistically significant trend to exacerbating disease. Optimally timed topical dexamethasone suppression of neovascularization in OIR was associated with increased retinal mitochondrial gene expression and decreased inflammatory marker expression, predominantly found in immune cells. Blocking mitochondrial ATP synthetase reversed the inhibitory effect of dexamethasone on neovascularization in OIR. This study provides new insights into topical steroid effects in retinal neovascularization and into mitochondrial function in phase II ROP, and suggests a simple clinical approach to prevent severe ROP.

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.

Systemic Arterial and Venous Thrombotic Events Associated With Anti-Vascular Endothelial Growth Factor Injections: A Meta-Analysis

PURPOSE

To compare the risk of systemic arteriovenous thrombotic events between intravitreal anti-vascular endothelial growth factor (anti-VEGF) and sham injections.

DESIGN

Random-effects meta-analysis.

METHODS

A systematic search was performed on OVID MEDLINE, Embase, and Cochrane Library from January 2005 to August 2023. Our inclusion criteria were randomized controlled trials (RCTs) reporting on systemic arteriovenous events for standard dose intravitreal anti-VEGF agents for any indication.

RESULTS

A total of 20 RCTs reporting on 12,833 eyes were included. There was no significant difference in the risk of any thrombotic event between bevacizumab 1.25 mg and ranibizumab 0.5 mg (Risk ratio (RR) = 0.96, 95% CI = 0.52-1.75, P = .89). There was no significant difference between bevacizumab and ranibizumab when restricting to arterial thrombotic events (RR= 0.88, 95% CI = 0.60-1.30, P = .53) or venous thrombotic events (RR = 1.99, 95% CI =86 0.68-5.82], P = .21). The risk of arterial thrombotic events was similar between aflibercept and bevacizumab (RR = 1.11, 95% CI = 0.60-2.07, P = .74), between aflibercept and ranibizumab (RR= 0.77, 95% CI = 0.49-1.21, P = .26), between brolucizumab and aflibercept (RR= 0.67, 95% CI = 0.32-1.38, P = .27), and between aflibercept and faricimab (RR = 0.96, 95% CI = 0.43-2.17, P = .93). Compared to sham, neither dose of ranibizumab (0.5 mg or 0.3 mg) showed a higher risk of arterial thrombotic events.

CONCLUSIONS

There was a similar risk of systemic arteriovenous thrombotic adverse events between anti-VEGF agents and between ranibizumab and sham injections.

Posterior eye delivery of angiogenesis-inhibiting RNA nanoparticles via subconjunctival injection

Neovascularization contributes to various posterior eye segment diseases such as age-related macular degeneration and diabetic retinopathy. RNA nanoparticles were demonstrated previously to enter the corneal and retinal cells after subconjunctival injection for ocular delivery. In the present study, antiangiogenic aptamers (anti-vascular endothelial growth factor (VEGF) and anti-angiopoietin-2 (Ang2) aptamers) were conjugated to RNA nanoparticles. The objectives were to investigate the clearance and distribution of these angiogenesis-inhibiting RNA nanoparticles after subconjunctival injection in vivo and their antiangiogenic effects for inhibiting ocular neovascularization in vitro. The results in the whole-body fluorescence imaging study showed that the clearance of RNA nanoparticles was size-dependent with no significant differences between RNA nanoparticles with and without the aptamers except for pRNA-3WJ. The distribution study of RNA nanoparticles by confocal microscopy of the dissected eye tissues in vivo indicated cell internalization of the larger RNA nanoparticles in the retina and retinal pigment epithelium after subconjunctival injection, and the larger nanoparticles with aptamers showed higher levels of cell internalization than those without. In the cell proliferation assay in vitro, RNA nanoparticles with multiple aptamers had higher antiangiogenic effects. With both longer retention time and high antiangiogenic effect, SQR-VEGF-Ang2 could be a promising RNA nanoparticle for posterior eye delivery.

Exploration of potential novel drug targets for diabetic retinopathy by plasma proteome screening

The aim of this study is to identify novel potential drug targets for diabetic retinopathy (DR). A bidirectional two-sample Mendelian randomization (MR) analysis was performed using protein quantitative trait loci (pQTL) of 734 plasma proteins as the exposures and clinically diagnosed DR as the outcome. Genetic instruments for 734 plasma proteins were obtained from recently published genome-wide association studies (GWAS), and external plasma proteome data was retrieved from the Icelandic Decoding Genetics Study and UK Biobank Pharma Proteomics Project. Summary-level data of GWAS for DR were obtained from the Finngen Consortium, comprising 14,584 cases and 202,082 population controls. Steiger filtering, Bayesian co-localization, and phenotype scanning were used to further verify the causal relationships calculated by MR. Three significant (p < 6.81 × 10-5) plasma protein-DR pairs were identified during the primary MR analysis, including CFH (OR = 0.8; 95% CI 0.75-0.86; p = 1.29 × 10-9), B3GNT8 (OR = 1.09; 95% CI 1.05-1.12; p = 5.9 × 10-6) and CFHR4 (OR = 1.11; 95% CI 1.06-1.16; p = 1.95 × 10-6). None of the three proteins showed reverse causation. According to Bayesian colocalization analysis, CFH (coloc.abf-PPH4 = 0.534) and B3GNT8 (coloc.abf-PPH4 = 0.638) in plasma shared the same variant with DR. All three identified proteins were validated in external replication cohorts. Our research shows a cause-and-effect connection between genetically determined levels of CFH, B3GNT8 and CFHR4 plasma proteins and DR. The discovery implies that these proteins hold potential as drug target in the process of developing drugs to treat DR.

The Role of Natural Products in Diabetic Retinopathy

Diabetic retinopathy (DR) is one of the most severe complications of diabetes mellitus and potentially leads to significant visual impairment and blindness. The complex mechanisms involved in the pathological changes in DR make it challenging to achieve satisfactory outcomes with existing treatments. Diets conducive to glycemic control have been shown to improve outcomes in diabetic patients, thus positioning dietary interventions as promising avenues for DR treatment. Investigations have demonstrated that natural products (NPs) may effectively manage DR. Many types of natural compounds, including saponins, phenols, terpenoids, flavonoids, saccharides, alkaloids, and vitamins, have been shown to exert anti-inflammatory, antioxidant, anti-neovascular, and antiapoptotic effects in vivo and in vitro. Nevertheless, the clinical application of NPs still faces challenges, such as suboptimal specificity, poor bioavailability, and a risk of toxicity. Prospective clinical studies are imperative to validate the therapeutic potential of NPs in delaying or preventing DR.

Therapeutic Effects of Anti-Inflammatory and Anti-Oxidant Nutritional Supplementation in Retinal Ischemic Diseases

Appropriate nutrients are essential for cellular function. Dietary components can alter the risk of systemic metabolic diseases, including cardiovascular diseases, cancer, diabetes, and obesity, and can also affect retinal diseases, including age-related macular degeneration, diabetic retinopathy, and glaucoma. Dietary nutrients have been assessed for the prevention or treatment of retinal ischemic diseases and the diseases of aging. In this article, we review clinical and experimental evidence concerning the potential of some nutritional supplements to prevent or treat retinal ischemic diseases and provide further insights into the therapeutic effects of nutritional supplementation on retinopathies. We will review the roles of nutrients in preventing or protecting against retinal ischemic diseases.

Influence of serial intravitreal injections on measures of dry eye: A systemic review and meta-analysis

PURPOSE

The aim of this study was to evaluate the long-term effects of serial intravitreal injections (IVI) on measures of dry eye.

METHODS

The PubMed, EMBASE, and Cochrane databases were searched according to the PROSPERO protocol (CRD42023455727). Studies evaluating the influence of serial IVI on the ocular surface compared with untreated fellow eyes were included. The measures of dry eye after IVI were used as outcome variables. The results are presented as mean difference (MD) with a corresponding 95% confidence interval (CI).

RESULTS

A total of 4 studies with 259 participants were included in this meta-analysis. Significant increases in ocular surface disease index (OSDI) scores (MD 10.26, 95 % CI 5.05 to 15.46, p ＜ 0.01) and tear film osmolarity (TOsm; MD 4.40, 95 % CI 0.87 to 7.92, p = 0.01) were observed in the IVI treated eyes compared to the untreated fellow eyes. There was no significant difference between the groups with respect to fluorescein tear film break-up time (TBUT; p = 0.05), average non-invasive tear film break-up time (NITBUT; p = 0.94), first NITBUT (p = 0.78) and Schirmer test (p = 0.94).

CONCLUSION

Repeated IVI of anti-VEGF agents with preoperative povidone-iodine application was associated with increased OSDI scores and TOsm, while no significant difference was found in fluorescein TBUT, average NITBUT, first NITBUT and Schirmer test. The ocular surface may partially recover after the procedures, but IVI still has deleterious effects on the ocular surface.

Dose-Related Side Effects of Intravitreal Injections of Humanized Anti-Vascular Endothelial Growth Factor in Rats: Glial Cell Reactivity and Retinal Ganglion Cell Loss

Purpose

In a previous study, we documented that the Intravitreal injections (IVIs) of bevacizumab in rats caused a retinal inflammatory response. We now study whether the IVI of other humanized anti-VEGF: ranibizumab and aflibercept also cause an inflammatory reaction in the rat retina and if it depends on the dose administered. Finally, we study whether this reaction affects retinal ganglion cell (RGC) survival.

Methods

Albino Sprague-Dawley rats received a single IVI of 5 µL of PBS or ranibizumab or aflibercept at the concentration used in clinical practice (10 µg/µL or 40 µg/µL) or at a lower concentration (0.38 µg/µL and 1.5 µg/µL) calculated to obtain within the rat eye the same concentration as in the human eye in clinical practice. Others received a single 5 µL IVI of a polyclonal goat anti-rat VEGF (0.015 µg/µL) or of vehicle (PBS). Animals were processed 7 days or 1 month later. Retinal whole mounts were immunolabeled for the detection of microglial, macroglial, RGCs, and intrinsically photosensitive RGCs (ipRGCs). Fluorescence and confocal microscopy were used to examine retinal changes, and RGCs and ipRGCs were quantified automatically or semiautomatically, respectively.

Results

All the injected substances including the PBS induced detectable side effects, namely, retinal microglial cell activation and retinal astrocyte hypertrophy. However, there was a greater microglial and macroglial response when the higher concentrations of ranibizumab and aflibercept were injected than when PBS, the antibody anti-rat VEGF and the lower concentrations of ranibizumab or aflibercept were injected. The higher concentration of ranibizumab and aflibercept resulted also in significant RGC death, but did not cause appreciable ipRGC death.

Conclusions

The IVI of all the substances had some retinal inflammatory effects. The IVI of humanized anti-VEGF to rats at high doses cause important side effects: severe inflammation and RGC death, but not ipRGC death.

Exosomal noncoding RNA: A potential therapy for retinal vascular diseases

Exosomes are extracellular vesicles that can contain DNA, RNA, proteins, and metabolites. They are secreted by cells and play a regulatory role in various biological responses by mediating cell-to-cell communication. Moreover, exosomes are of interest in developing therapies for retinal vascular disorders because they can deliver various substances to cellular targets. According to recent research, exosomes can be used as a strategy for managing retinal vascular diseases, and they are being investigated for therapeutic purposes in eye conditions, including glaucoma, dry eye syndrome, retinal ischemia, diabetic retinopathy, and age-related macular degeneration. However, the role of exosomal noncoding RNA in retinal vascular diseases is not fully understood. Here, we reviewed the latest research on the biological role of exosomal noncoding RNA in treating retinal vascular diseases. Research has shown that noncoding RNAs, including microRNAs, circular RNAs, and long noncoding RNAs play a significant role in the regulation of retinal vascular diseases. Furthermore, through exosome engineering, the expression of relevant noncoding RNAs in exosomes can be controlled to regulate retinal vascular diseases. Therefore, this review suggests that exosomal noncoding RNA could be considered as a biomarker for diagnosis and as a therapeutic target for treating retinal vascular disease.

A real-world disproportionality analysis of anti-VEGF drugs from the FDA Adverse Event Reporting System

BACKGROUND

The association between anti-vascular endothelial growth factor (VEGF) drugs and ocular adverse events (AEs) has been reported, but large real-world studies of their association with systemic AEs are still lacking.

METHODS

A disproportionality analysis of reports from the FDA Adverse Event Reporting System from January 2004 to September 2021 was conducted to detect the significant ADR signals with anti-VEGF drugs (including aflibercept, bevacizumab, brolucizumab, pegaptanib, and ranibizumab).

RESULTS

A total of 2980 reported cases with 7125 drug-AEs were included. Five drugs were all associated with eye disorders, and pegaptanib and ranibizumab were also associated with cardiac disorders. For ranibizumab, pegaptanib, bevacizumab and aflibercept, the proportions of cardiac AEs were 8.57%, 5.62%, 3.43% and 3.20%, respectively, and the proportions of central nervous AEs were 8.81%, 7.41, 5.86% and 5.68%, respectively. In multiple comparisons, ranibizumab was significantly higher than bevacizumab and aflibercept in the proportion of cardiac AEs (P < 0.001), and ranibizumab was significantly higher than aflibercept in central nervous AEs (P < 0.001).

CONCLUSIONS

Our findings support the associations between anti-VEGF drugs and ocular AEs, cardiac AEs, and central nervous AEs. After intravitreal injection, attention should not only be paid to ocular symptoms, but also to systemic symptoms.

The Treatment of Diabetic Retinal Edema with Intravitreal Steroids: How and When

Diabetic macular edema (DME) is a common complication of diabetes mellitus and a leading cause of visual impairment worldwide. It is defined as the diabetes-related accumulation of fluid, proteins, and lipids, with retinal thickening, within the macular area. DME affects a significant proportion of individuals with diabetes, with the prevalence increasing with disease duration and severity. It is estimated that approximately 25-30% of diabetic patients will develop DME during their lifetime. Poor glycemic control, hypertension, hyperlipidemia, diabetes duration, and genetic predisposition are recognized as risk factors for the development and progression of DME. Although the exact pathophysiology is still not completely understood, it has been demonstrated that chronic hyperglycemia triggers a cascade of biochemical processes, including increased oxidative stress, inflammation, activation of vascular endothelial growth factor (VEGF), cellular dysfunction, and apoptosis, with breakdown of the blood-retinal barriers and fluid accumulation within the macular area. Early diagnosis and appropriate management of DME are crucial for improving visual outcomes. Although the control of systemic risk factors still remains the most important strategy in DME treatment, intravitreal pharmacotherapy with anti-VEGF molecules or steroids is currently considered the first-line approach in DME patients, whereas macular laser photocoagulation and pars plana vitrectomy may be useful in selected cases. Available intravitreal steroids, including triamcinolone acetonide injections and dexamethasone and fluocinolone acetonide implants, exert their therapeutic effect by reducing inflammation, inhibiting VEGF expression, stabilizing the blood-retinal barrier and thus reducing vascular permeability. They have been demonstrated to be effective in reducing macular edema and improving visual outcomes in DME patients but are associated with a high risk of intraocular pressure elevation and cataract development, so their use requires an accurate patient selection. This manuscript aims to provide a comprehensive overview of the pathology, epidemiology, risk factors, physiopathology, clinical features, treatment mechanisms of actions, treatment options, prognosis, and ongoing clinical studies related to the treatment of DME, with particular consideration of intravitreal steroids therapy.

PFKFB3 in neovascular eye disease: unraveling mechanisms and exploring therapeutic strategies

BACKGROUND

Neovascular eye disease is characterized by pathological neovascularization, with clinical manifestations such as intraocular exudation, bleeding, and scar formation, ultimately leading to blindness in millions of individuals worldwide. Pathologic ocular angiogenesis often occurs in common fundus diseases including proliferative diabetic retinopathy (PDR), age-related macular degeneration (AMD), and retinopathy of prematurity (ROP). Anti-vascular endothelial growth factor (VEGF) targets the core pathology of ocular angiogenesis.

MAIN BODY

In recent years, therapies targeting metabolism to prevent angiogenesis have also rapidly developed, offering assistance to patients with a poor prognosis while receiving anti-VEGF therapy and reducing the side effects associated with long-term VEGF usage. Phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), a key enzyme in targeted metabolism, has been shown to have great potential, with antiangiogenic effects and multiple protective effects in the treatment of neovascular eye disease. In this review, we summarize the mechanisms of common types of neovascular eye diseases; discuss the protective effect and potential mechanism of targeting PFKFB3, including the related inhibitors of PFKFB3; and look forward to the future exploration directions and therapeutic prospects of PFKFB3 in neovascular eye disease.

CONCLUSION

Neovascular eye disease, the most common and severely debilitating retinal disease, is largely incurable, necessitating the exploration of new treatment methods. PFKFB3 has been shown to possess various potential protective mechanisms in treating neovascular eye disease. With the development of several drugs targeting PFKFB3 and their gradual entry into clinical research, targeting PFKFB3-mediated glycolysis has emerged as a promising therapeutic approach for the future of neovascular eye disease.

Clinical efficacy of subthreshold micropulse laser combined with anti-VEGF drugs in the treatment of diabetic macular edema: A meta-analysis

BACKGROUND

To systematically evaluate the efficacy and safety of subthreshold micropulse laser (SML) combined with anti-vascular endothelial growth factor (VEGF) drugs for the treatment of diabetic macular edema (DME).

METHODS

The randomized controlled trials on SML combined with anti-VEGF drugs for DME were retrieved from China National Knowledge Infrastructure, Wan Fang Data, VIP Data, Sino Med (China Biomedical Literature Database), PubMed, Web of Science, The Cochrane Library, and Embase by computer from inception to April 19, 2022. The observation group was treated with SML combined with anti-VEGF drugs, while the control group was treated with anti-VEGF agents alone or SML. And the references of the included literature were manually searched. The Meta-analysis was performed using Revman 5.4 and STATA SE 15.

RESULTS

This study finally included 15 randomized controlled trials involving 891 eyes for Meta-analysis. The results showed that there was no statistically significant difference between the 2 groups in best-corrected visual acuity at 1, 3, 6, 9, and 12 months after treatment. There was no statistical difference between the 2 groups in central macular thickness (CMT) at 1, 3, and 6 months after treatment (P > .05). CMT in the observation group was lower than that in the control group at 9 and 12 months (P < .05). There was no statistical difference between the 2 groups in total macular volume at 3, 6, 9, and 12 months in CMT (P > .05). The number of anti-VEGF drugs injections in the observation was lower than that in the control group (P < .05). The occurrence of complications between the 2 groups was not statistically significant difference (P > .05).

CONCLUSION

SML in combination with anti-VEGF drugs in patients with DME are comparable in reducing the number of anti-VEGF drugs injections and CMT, thereby reducing the financial burden on patients. It does not differ in best-corrected visual acuity and total macular volume.

New concepts drive the development of delivery tools for sustainable treatment of diabetic complications

Diabetic complications, especially diabetic retinopathy, diabetic nephropathy and painful diabetic neuropathy, account for a large portion of patients with diabetes and display rising global prevalence. They are the leading causes of blindness, kidney failure and hypersensitivity to pain caused by diabetes. Current approved therapeutics against the diabetic complications are few and exhibit limited efficacy. The enhanced cell-specificity, stability, biocompatibility, and loading capacity of drugs are essential for the mitigation of diabetic complications. In the article, we have critically discussed the recent studies over the past two years in material sciences and biochemistry. The insightful concepts in these studies drive the development of novel nanoparticles and mesenchymal stem cells-derived extracellular vesicles to meet the need for treatment of diabetic complications. Their underlying biochemical principles, advantages and limitations have been in-depth analyzed. The nanoparticles discussed in the article include double-headed nanodelivery system, nanozyme, ESC-HCM-B system, soft polymer nanostars, tetrahedral DNA nanostructures and hydrogels. They ameliorate the diabetic complication through attenuation of inflammation, apoptosis and restoration of metabolic homeostasis. Moreover, mesenchymal stem cell-derived extracellular vesicles efficiently deliver therapeutic proteins to the retinal cells to suppress the angiogenesis, inflammation, apoptosis and oxidative stress to reverse diabetic retinopathy. Collectively, we provide a critical discussion on the concept, mechanism and therapeutic applicability of new delivery tools to treat these three devastating diabetic complications.

Regression of Neovascularization after Panretinal Photocoagulation Combined with Anti-VEGF Injection for Proliferative Diabetic Retinopathy-A Review

Proliferative diabetic retinopathy (PDR) poses a significant therapeutic problem that often results in severe visual loss. Panretinal photocoagulation (PRP) has long been a mainstay treatment for this condition. Conversely, intravitreal anti-VEGF therapy has served as an alternative treatment for PDR. This review aimed to evaluate the effects of PRP combined with anti-VEGF therapy on the regression of neovascularization (NV), including functional outcomes and incidence of complications. The MEDLINE database was searched for articles evaluating regression of NV using a combination of the following terms: "proliferative diabetic retinopathy", "anti-VEGF", "panretinal photocoagulation", and "combined treatment". The search yielded a total of 22 articles. The analysis of their results indicated PRP combined with ant-VEGF therapy as superior over PRP alone in the management of PDR. Combination treatment yields better and faster regression of NV and a lower incidence of serious complications, such as vitreous hemorrhage and the need for pars plana vitrectomy. Nevertheless, complete regression of NV is not achieved in a significant proportion of patients. Further research is needed to establish the most effective schedule for intravitreal injections as an adjunct to PRP. The current literature shows that in some cases, cessation of anti-VEGF injection in combination treatment for PDR can lead to relapse of NV.

PACAP-ADNP axis prevents outer retinal barrier breakdown and choroidal neovascularization by interfering with VEGF secreted from retinal pigmented epitelium cells

During diabetic retinopathy (DR) progression, the retina undergoes various metabolic changes, including hypoxia-signalling cascade induction in the cells of retinal pigmented epithelium (RPE). The overexpression of hypoxic inducible factors causes transcription of many target genes including vascular endothelial growth factor (VEGF). The RPE cells form the outer blood retinal barrier (oBRB), a specialized structure that regulates ions and metabolites flux into the retina to maintain a suitable quality of its extracellular microenvironment. VEGF worsens retinal condition since its secretion from the basolateral compartment of RPE cells compromises the barrier's integrity and induces choroidal neovascularization. In this work, we hypothesized that PACAP prevents the damage to oBRB and controls choroidal neovascularization through the induction of ADNP. Firstly, we demonstrated that ADNP is expressed in Streptozotocin (STZ)-induced diabetic animals. To validate our hypothesis, we cultured endothelial cells (H5V) forming vessels-like structures, in a conditioned medium (CM) derived from ARPE-19 cells exposed to hyperglycaemic/hypoxic insult, containing a known VEGF concentration. The involvement of PACAP-ADNP axis on oBRB integrity was evaluated through the measurement of trans-epithelial-electrical resistance and permeability assay performed on ARPE cell monolayer cultured in CM and by analysing the expression of two tight junction forming proteins, ZO1 and occludin. By culturing H5V in CM, we demonstrated that PACAP-ADNP axis counteracted vessels-like structures formation promoted by VEGF. In conclusion, the results suggested a primary role of PACAP/ADNP axis in preventing oBRB damage and in controlling aberrant choroidal neovascularization induced by VEGF secreted from RPE cells exposed to hyperglycaemia/hypoxic insult in DR.

1,8-Cineole ameliorates diabetic retinopathy by inhibiting retinal pigment epithelium ferroptosis via PPAR-γ/TXNIP pathways

1,8-Cineole, the main component of volatile oil in aromatic plants, has diverse pharmacological properties, including antioxidant, anti-inflammatory, and anti-cancer properties. Diabetic retinopathy (DR) is a common microvascular complication of diabetes mellitus (DM). Here, we investigated the protective effect of 1,8-cineole on DR and found that 1,8-cineole treatment could alter the expression of several genes in both high glucose (HG)-induced ARPE-19 cells and retinal tissues of DM mice, as well as inhibit ferroptosis. Subsequent investigations into the molecular mechanisms underlying this inhibition revealed that expression of thioredoxin-interacting protein (TXNIP) was significantly upregulated while that of peroxisome proliferator-activated receptor γ (PPAR-γ) was significantly downregulated in HG-induced ARPE-19 cells, and treatment with 1,8-cineole could effectively reverse these changes. Treatment with a PPAR-γ pharmacological agonist (rosiglitazone), alone or combined with 1,8-cineole, significantly inhibited the transcription of TXNIP and ferroptosis in HG-induced ARPE-19 cells. Conversely, pretreatment with GW9662, a PPAR-γ inhibitor, upregulated the transcription and expression of TXNIP in HG-induced ARPE-19 cells; 1,8-cineole failed to reverse this upregulated expression. To explore these relationships, we constructed a PPAR-γ adenovirus shRNA to elucidate the effect of 1,8-cineole on the negative regulation of TXNIP by PPAR-γ. Taken together, the present findings indicate that HG-induced ferroptosis in retinal tissue plays an essential role in the pathogenesis of DR, which can be ameliorated by 1,8-cineole.

Vaccinium as Potential Therapy for Diabetes and Microvascular Complications

Diabetes mellitus is one of the most critical global health concerns, with a fast-growing prevalence. The incidence of diabetic vascular complications is also rapidly increasing, exacerbating the burden on individuals with diabetes and the consumption of public medical resources. Despite the overall improvements in the prevention, diagnosis, and treatment of diabetic microvascular complications in recent years, safe and effective alternative or adjunctive therapies are urgently needed. The mechanisms underlying diabetic vascular complications are complex, with hyperglycemia-induced oxidative stress and inflammation being the leading causes. Therefore, glycemic control, antioxidation, and anti-inflammation are considered the main targets for the treatment of diabetes and its vascular comorbidities. Vaccinium L. (Ericaceae) is a genus of plants enriched with polyphenolic compounds in their leaves and fruits. Vaccinium and its extracts have demonstrated good bioactivity in reducing blood glucose, oxidative stress, and inflammation, making them excellent candidates for the management of diabetes and diabetic vascular complications. Here, we review recent preclinical and clinical studies on the potential effect of Vaccinium on ameliorating diabetes and diabetic complications, particularly diabetic kidney disease and diabetic retinopathy.

Antioxidant Phytochemicals as Potential Therapy for Diabetic Complications

The global prevalence of diabetes continues to increase partly due to rapid urbanization and an increase in the aging population. Consequently, this is associated with a parallel increase in the prevalence of diabetic vascular complications which significantly worsen the burden of diabetes. For these diabetic vascular complications, there is still an unmet need for safe and effective alternative/adjuvant therapeutic interventions. There is also an increasing urge for therapeutic options to come from natural products such as plants. Hyperglycemia-induced oxidative stress is central to the development of diabetes and diabetic complications. Furthermore, oxidative stress-induced inflammation and insulin resistance are central to endothelial damage and the progression of diabetic complications. Human and animal studies have shown that polyphenols could reduce oxidative stress, hyperglycemia, and prevent diabetic complications including diabetic retinopathy, diabetic nephropathy, and diabetic peripheral neuropathy. Part of the therapeutic effects of polyphenols is attributed to their modulatory effect on endogenous antioxidant systems. This review attempts to summarize the established effects of polyphenols on endogenous antioxidant systems from the literature. Moreover, potential therapeutic strategies for harnessing the potential benefits of polyphenols for diabetic vascular complications are also discussed.

The role of aldosterone in the pathogenesis of diabetic retinopathy

Aldosterone, as a mineralocorticoid of adrenal origin, has effects that are not limited to the urinary tract. As an important regulator in Vasoactive hormone pathways, aldosterone may play an effect in the pathogenesis of diabetic retinopathy (DR) through the regulation of oxidative stress, vascular regulation, and inflammatory mechanisms. This implies that mineralocorticoids, including aldosterone, have great potential and value for the diagnosis and treatment of DR. Because early studies did not focus on the intrinsic association between mineralocorticoids and DR, targeted research is still in its infancy and there are still many obstacles to its application in the clinical setting. Recent studies have improved the understanding of the effects of aldosterone on DR, and we review them with the aim of exploring possible mechanisms for the treatment and prevention of DR.