Vascular endothelial growth factor biology: clinical implications for ocular treatments

45S5 Bioactive Glass-Ointment Positively Effects on Wound Healing in Rats by Regulating TNFα, Il-10, VEGF, and TGFβ

AIM

This study aimed to investigate the effects of 45S5 bioactive glass-ointment (BG) on cutaneous wound healing in rats at the molecular, biochemical, and histopathological levels.

MATERIALS AND METHODS

Thirty-two rats were divided into four groups (n = 8): Control, Sham, BG, and DEX (Dexpanthenol). While no wound treatment was applied to the CONTROL, a wound model was created in the Sham, and no treatment was applied. A wound model was created for other groups, and BG and DEX were applied locally for 21 days. During the 21-day experiment period, feed and water consumption and weight changes were observed. Wound areas were calculated on days 0, 3, 7, 4, and 21. Following treatment, the rats were euthanized and tissues from the wound area and blood samples were collected. While the expression levels of tumor necrosis factor-alpha (TNFα), Interleukin 6 (IL6), Interleukin 10 (IL10), transforming growth factor-beta (TGFβ), and vascular endothelial growth factor (VEGF) genes were determined by qPCR, the levels of TNFα, IL6, and IL10 proteins were measured by ELISA.

RESULTS

It was observed that the BG group showed anti-inflammatory activity by suppressing TNFα levels and stimulating IL-10. In addition, it was determined that BG increased fibroblast activity and vascularization.

CONCLUSION

Current findings showed that topical application of BG has anti-inflammatory effects, while also accelerating healing by increasing vascularity and making positive contributions to tissue healing.

An Ensemble Docking Approach for Analyzing and Designing Aptamer Heterodimers Targeting VEGF165

Vascular endothelial growth factor 165 (VEGF165) is a prominent isoform of the VEGF-A protein that plays a crucial role in various angiogenesis-related diseases. It is homodimeric, and each of its monomers is composed of two domains connected by a flexible linker. DNA aptamers, which have emerged as potent therapeutic molecules for many proteins with high specificity and affinity, can also work for VEGF165. A DNA aptamer heterodimer composed of monomers of V7t1 and del5-1 connected by a flexible linker (V7t1:del5-1) exhibits a greater binding affinity with VEGF165 compared to either of the two monomers alone. Although the structure of the complex formed between the aptamer heterodimer and VEGF165 is unknown due to the highly flexible linkers, gaining structural information will still be valuable for future developments. Toward this end of accessing structural information, we adopt an ensemble docking approach here. We first obtain an ensemble of structures for both VEGF165 and the aptamer heterodimer by considering both small- and large-scale motions. We then proceed through an extraction process based on ensemble docking, molecular dynamics simulations, and binding free energy calculations to predict the structures of the VEGF165/V7t1:del5-1 complex. Through the same procedures, we reach a new aptamer heterodimer that bears a locked nucleic acid-modified counterpart of V7t1, namely RNV66:del5-1, which also binds well with VEGF165. We apply the same protocol to the monomeric units V7t1, RNV66, and del5-1 to target VEGF165. We observe that V7t1:del5-1 and RNV66:del5-1 show higher binding affinities with VEGF165 than any of the monomers, consistent with experiments that support the notion that aptamer heterodimers are more effective anti-VEGF165 aptamers than monomeric aptamers. Among the five different aptamers studied here, the newly designed RNV66:del5-1 shows the highest binding affinity with VEGF165. We expect that our ensemble docking approach can help in de novo designs of homo/heterodimeric anti-angiogenic drugs to target the homodimeric VEGF165.

Short Term Effect of Pre-Operative Anti-VEGF on Angiogenic and Fibrotic Profile of Fibrovascular Membranes of Proliferative Diabetic Retinopathy

Purpose

Adjuvant, pre-operative intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections have been used to reduce peri-operative bleeding in eyes undergoing pars-plana vitrectomy for complications of proliferative diabetic retinopathy (PDR). To address the concern over their potential off-target effects of progressive fibrous contraction, we sought to dissect the transcriptional changes in the surgically extracted fibrovascular membranes (FVMs).

Methods

We analyzed surgically extracted FVMs from 10 eyes: 4 eyes pretreated with intravitreal bevacizumab (IVB) and 6 untreated eyes. FVMs were digested into single cells, mRNA was extracted from endothelial cell-enriched (microbead selection with CD31) and non-endothelial cell compartments, followed by RT-qPCR quantification. We then compared the relative expression of genes involved in angiogenesis, endothelial cell integrity, and myofibroblastic processes between treated and untreated FVMs.

Results

Endothelial cells from IVB pretreated FVMs showed significant reduction of VEGFA, VEGF receptors (FLT1 and KDR), and angiopoietin 2 expression as well as increased vascular endothelial cadherin and endothelin, suggesting reduced angiogenesis and enhanced vascular integrity. The non-endothelial cell fraction showed decreased expression of VEGFA and fibronectin, without significant difference in the expression of other profibrotic factors.

Conclusions

Our findings confirm that adjuvant pre-operative IVB decreased fibronectin and increase endothelin-1 expression without affecting other profibrotic gene expression, uncovering an important interaction between IVB and endothelin-1 that deserves further study.

Kaempferol protects gut-vascular barrier from high glucose-induced disorder via NF-κB pathway

Kaempferol is a natural edible flavonoid reported to treat high-fat diet-induced intestinal inflammation; however, the underlying molecular mechanisms remain unclear. This research aims to investigate the protective effect of kaempferol on the gut-vascular barrier (GVB) induced by high glucose and elucidate the underlying mechanism. Evans blue albumin efflux assay was used to test endothelial cell permeability. The results showed that kaempferol (50 μM) significantly reversed the high glucose-induced monolayer barrier permeability of rat intestinal microvascular endothelial cells (RIMVECs), while kaempferol significantly alleviated the high glucose-induced rarefication of the tight junction protein Claudin-5. Moreover, kaempferol also reduced high glucose-induced angiogenesis and cell migration via inhibiting the VEGFR2/p38 pathway. Kaempferol also protected against high glucose-induced overproduction of intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 by inhibiting NF-κB p65 nuclear translocation. In addition, kaempferol had similar effects to the NF-κB inhibitor SN50 in reducing high glucose-induced ICAM-1 expression and endothelial barrier permeabilization. Our findings in part reveal the pathological mechanism of hyperglycemia-related gastrointestinal diseases and underlie the molecular mechanism of kaempferol in inhibiting bowel inflammation from a novel perspective.

Intravitreal Anti-Vascular Endothelial Growth Factor Therapies for Retinal Disorders

Vascular endothelial growth factors (VEGFs) are key mediator of retinal and choroidal neovascularization as well as retinal vascular leakage leading to macular edema. As such, VEGF plays an important role in mediating visually significant complications associated with common retinal disorders such as diabetic retinopathy, retinal vein occlusion, and age-related macular degeneration. Various drugs that inhibit vascular endothelial growth factors (anti-VEGF therapies) have been developed to minimize vision loss associated with these disorders. These drugs are injected into the vitreous cavity in a clinic setting at regular intervals. This article provides an overview of the various anti-VEGF drugs used in ophthalmology and the common retinal conditions that benefit from this therapy.

High VEGF Concentrations Accelerate Human Trabecular Meshwork Fibrosis in a TAZ-Dependent Manner

We aimed to investigate the effects of different concentrations of vascular endothelial growth factor (VEGF) on the extracellular matrix (ECM) and fibrotic proteins in human trabecular meshwork (TM) cells. We also explored how the Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ) signaling pathway modulates VEGF-induced fibrosis. We determined cross-linked actin network (CLAN) formation using TM cells. Changes in fibrotic and ECM protein expression were determined. High VEGF concentrations (10 and 30 ng/mL) increased TAZ and decreased p-TAZ/TAZ expression in TM cells. Western blotting and real-time PCR revealed no YAP expression changes. Fibrotic and ECM protein expression decreased at low VEGF concentrations (1 and 10 ρg/mL) and significantly increased at high VEGF concentrations (10 and 30 ng/mL). CLAN formation increased in TM cells treated with high VEGF concentrations. Moreover, TAZ inhibition by verteporfin (1 μM) rescued TM cells from high-VEGF-concentration-induced fibrosis. Low VEGF concentrations reduced fibrotic changes, whereas high VEGF concentrations accelerated fibrosis and CLAN formations in TM cells in a TAZ-dependent manner. These findings reflect the dose-dependent influences of VEGF on TM cells. Moreover, TAZ inhibition might be a therapeutic target for VEGF-induced TM dysfunction.

Association between Systemic Factors and Vitreous Fluid Cytokines in Proliferative Diabetic Retinopathy

Proliferative diabetic retinopathy (PDR) is a vision-threatening complication of diabetes mellitus (DM). Systemic and intraocular factors are intricately related to PDR, and vitreous fluid (VF) cytokines are representative intraocular biomarkers. However, the associations between systemic factors and VF cytokines and their influence on PDR pathology are unclear. This study aimed to examine the correlation between systemic factors and VF cytokines and analyze their contributions to the pathology of PDR using multivariate analyses. We conducted a retrospective observational study on 26 PDR eyes of 25 patients with type 2 DM, and 30 eyes of 30 patients with idiopathic macular hole or epiretinal membrane as controls. Fifteen systemic and laboratory tests including blood pressure (BP) and body mass index (BMI), and 27 cytokines in VF were analyzed. BP and BMI correlated positively with VF levels of IL-6 and IP-10 in PDR patients, while no significant correlation was found between systemic factors and VF cytokines in controls. MCP-1 and VEGF-A in VF separately clustered with different systemic factors in controls, but these cytokines lost the property similarity with systemic factors and acquired property similarity with each other in PDR. Systemic factors contributed to only 10.4%, whereas VF cytokines contributed to 42.3% out of 52.7% variance of the whole PDR dataset. Our results suggest that intraocular factors play a major role in the pathology of PDR, whereas systemic factors may have limited effects, and that BP and BMI control in PDR could be useful interventions to improve intraocular immune condition.

Application and mechanism of anti-VEGF drugs in age-related macular degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly. The incidence rate increases with age in people over 50 years of age. With the advent of China’s aging society, the number of patients is increasing year by year. Although researchers have done a lot of basic research and clinical research on the pathogenesis and treatment of AMD in recent years, the pathogenesis of AMD is still controversialdue to the complexity of the disease itself. AMD is the primary cause of blindness in the elderly over 50 years old. It is characterized by the formation of choroidal neovascularization (CNV) and the over secretion of vascular endothelial growth factor (VEGF) as its main mechanism, which can eventually lead to vision loss or blindness. The occurrence and development of AMD is an extremely complex process, in which a large number of regulatory factors and cytokines are involved. Most of the existing treatments are for its concomitant CNV. Targeted VEGF drugs for neovascularization, such as Lucentis and Aflibercept, are the first-line drugs for AMD. Their application has greatly reduced the blinding rate of patients. However, there are still some patients who have no response to treatment or cannot maintain their vision after long-term treatment. Frequent injection also increases the risk of complications and economic burden. In order to further improve the quality of life and long-term prognosis of AMD patients, a variety of new treatmentshave been or will be applied in clinic, including combined treatment with the same or different targets to improve the curative effect, change or simplify the mode of medication, inhibit VEGF receptor tyrosine protein kinase and so on. This article provides a brief review of the research progress of anti-VEGF drugs and their mechanisms for the treatment of AMD, it is expected to provide a better treatment plan for AMD treatment.

Protein and polypeptide mediated delivery to the eye

Hybrid or recombinant protein-polymers, peptide-based biomaterials, and antibody-targeted therapeutics are widely explored for various ocular conditions and vision correction. They have been noted for their potential biocompatibility, potency, adaptability, and opportunities for sustained drug delivery. Unique to peptide and protein therapeutics, their production by cellular translation allows their precise modification through genetic engineering. To a greater extent than drug delivery to other systems, delivery to the eye can benefit from the combination of locally-targeted administration and protein-based specificity. Consequently, a range of delivery platforms and administration methods have been exploited to address the ocular delivery of peptide and protein biomaterials. This review discusses a sample of preclinical and clinical opportunities for peptide-based drug delivery to the eye.

The Influence of COVID-19 on the Stability of Patients with Neovascular Age-Related Macular Degeneration with Different Treatment Regimens

Introduction

To explore the impact of coronavirus disease 2019 (COVID-19) on the stability of patients with neovascular age-related macular degeneration (nAMD) receiving the treat and extend (T&E) or the pro re nata (PRN) treatment regimen and to identify indicators that may predict the disease stability of nAMD.

Methods

This is a retrospective study of patients with nAMD treated at the Second Affiliated Hospital of Harbin Medical University whose treatment schedule was interrupted at least once between 1 February and 31 May 2020. The demographic and clinical characteristics, including the best corrected visual acuity (BCVA), optical coherence tomography (OCT) features, subfoveal choroidal thickness (SFCT), interval between the last injection and the beginning of the pandemic, and the number of anti-vascular endothelial growth factor (VEGF) injections, were analyzed.

Results

A total of 209 stable patients with nAMD (122 eyes received the T&E regimen; 87 eyes received the PRN regimen) were identified. Compared to those who received the PRN regimen, the patients who received the T&E regimen were more stable during the first visit after COVID-19 (53.3% vs. 33.3%, P = 0.004), the BCVA was significantly better (58.5 letters vs. 56 letters, P = 0.006), and the CRT fluctuated only slightly (15 μm vs. 35 μm, P = 0.001). Furthermore, a multivariate logistic regression analysis showed that stable patients with nAMD with type 1 choroidal neovascularization (CNV) (OR 2.493 [95% CI 1.179–5.272], compared with type 2 CNV; P = 0.017; OR 2.912 [95% CI 1.133–7.485], compared with retinal angiomatous proliferation; P = 0.026) or with pigment epithelial detachment (PED) were more likely to remain stable when treatment was interrupted (OR 0.392 [95% CI 0.181–0.852], compared with no PED; P = 0.018).

Conclusion

Compared to patients who received the PRN treatment regimen, stable patients with nAMD who received the T&E treatment regimen could better maintain stability when the treatments were suddenly interrupted by the COVID-19 pandemic. In addition, patients with type 1 CNV or patients with PED were more likely to remain stable. At present, the COVID-19 pandemic is becoming increasingly normalized, and the T&E regimen can become a more advanced treatment option for patients undergoing therapy.

Effects of the Presence of Pseudoexfoliation on Intraocular Pressure and Retinal Nerve Fiber Layer Thickness in Patients with Macular Degeneration Receiving Intravitreal Ranibizumab

Aims: In the present study, we aimed to compare the effect of intravitreal ranibizumab (IVR) treatment on intraocular pressure (IOP) and retinal nerve fiber layer (RNFL) thickness in patients with age-related macular degeneration (AMD) with and without pseudoexfoliation (PEX). Materials and Methods: A total of 24 patients, 12 with PEX (12 eyes) and 12 without PEX (12 eyes), receiving IVR treatment for neovascular AMD between June 2017 and June 2019, were included in the study. Exclusion criteria were composed of the history of glaucoma, uveitis, intravitreal steroid administration, pars plana vitrectomy surgery, and less than three IVR injections. Such criteria as age, gender, follow-up times, number of injections administered, IOP, and RNFL thickness before the first injection and one month after the last injection were also recorded. Results: Age, gender, follow-up time, and the number of injections were similar in groups with and without PEX (p > 0.05). While mean post-treatment IOP values were not significantly higher in the PEX group (14.50 ± 3.06 vs. 12.91 ± 1.83 mmHg, p = 0.065), the values were significant for the non-PEX group (13.25 ± 2.76 vs. 11.83 ± 2.69 mmHg, p = 0.01), and these values were within normal IOP limits. Additionally, RNFL thickness was significantly thinner after treatment in both groups (91.41 ± 7.14 vs. 94.00 ± 6.76 in those with PEX; 95.58 ± 5.91 vs. 97.66 ± 6.89 in those without PEX; p < 0.05). The decrease in RNFL thickness in the PEX group was 2.58 ± 1.62 µ and in the non-PEX group was 2.08 ± 1.98 µ. However, there was no statistically significant difference between the two groups in terms of RNFL thinning (p = 0.505). Discussion: Ranibizumab may reduce RNFL thickness in patients with PEX. Longer-term studies including larger populations are necessary for understanding IOP and RNFL changes after anti-vascular endothelial growth factor (anti-VEGF) injection.

The effects of loading ranibizumab on vision-related quality of life in the treatment of low-risk neovascular age-related macular degeneration

Background:

The loss of central vision plays a major role in the quality of life (QoL). This study evaluates the changes in QoL in the treatment of low-risk neovascular age-related macular degeneration (AMD).

Objectives:

The aim of this study was to evaluate the changes in vision-related QoL in patients receiving intravitreal ranibizumab loading dose for low-risk neovascular AMD.

Design:

A prospective study.

Methods:

Forty-two eyes of 42 patients receiving ranibizumab injections for neovascular AMD were included in this prospective study. The changes in best-corrected visual acuity (BCVA), central macular thickness (CMT) of the patients before the treatment, and 1 month after three loading doses were evaluated. Turkish version of the National Eye Institute 25-Item Vision Function Questionnaire (NEI VFQ-25 TR) was conducted. The changes of QoL scores through the NEI VFQ-25 TR questionnaire were compared with visual acuity (VA) and CMT measurements before the injections and 1 month after the loading dose.

Results:

Forty-two patients (19 females and 23 males) were included in the study, and the mean age was 72.69 ± 7.12 years. After the treatment, a statistically significant improvement in BCVA (0.98 ± 0.44, 0.76 ± 0.42 logMAR, p < 0.001) and a significant decrease in CMT (357.90 ± 71.71, 274.50 ± 58.35 μm, p < 0.001) was observed. The QoL composite score was found to be statistically significantly higher after the treatment (64.27 ± 11.47, 68.56 ± 11.39, p < 0.001). General vision (p < 0.001), ocular pain (p = 0.025), near activities (p < 0.001), distance activities (p = 0.027), vision-specific mental health (p = 0.014), vision-specific role difficulties (p < 0.001), and peripheral vision (p = 0.046) were significantly higher after the treatment.

Conclusion:

NEI VFQ-25 TR is a useful questionnaire for evaluating changes in visual functions and psychosocial characteristics of low-risk neovascular AMD patients before and after the injections.

Profiles of Cytokines Secreted by ARPE-19 Cells Exposed to Light and Incubated with Anti-VEGF Antibody

The retinal pigment epithelium (RPE) is the major source of cytokines in the retina regulating the intraocular immune environment, and a primary target of photodamage. Here, we examined 27 types of cytokines secreted by ARPE-19 cells exposed to visible light and incubated with aflibercept or ranibizumab, which are two anti-vascular endothelial growth factor (VEGF) antibodies. The cells were cultured for 24 h in the dark or under 2000 lux irradiation from a daylight-colored fluorescent lamp, and cytokine levels in the culture supernatant were measured. In the light-irradiated culture, the levels of IL-9, IL-17A and bFGF were higher, and the levels of IL-6, IL-7, IL-8 and MCP-1 were lower than those in the dark culture, while there was no significant difference with the VEGF-A level. In subgroup analyses of the light-irradiated culture, the bFGF level under 250 to 2000 lux irradiation was elevated in a light intensity-dependent manner. In culture exposed to blue, green or red light, the bFGF level was elevated by blue light and was high compared to that by green or red light. In culture with aflibercept or ranibizumab in the dark, the levels of IL-6, IL-8, bFGF and MCP-1 were increased, and the IL-12 level decreased synchronously with a reduction in the VEGF-A level. Our findings indicate that continuous irradiation of visible light and VEGF suppression may be an influential factor in expression patterns of inflammatory cytokines secreted by human RPE cells.

The Effect of Ranibizumab Loading Treatment on Vision-Related Quality of Life in Diabetic Macular Edema

AIMS

To investigate the changes in vision-related quality of life after a loading dose of three consecutive intravitreal ranibizumab (IVR) injections in patients with unilateral diabetic macular edema (DME).

MATERIALS AND METHODS

Fifty-two eyes of 52 patients who received IVR injections in only one eye with DME were included in our study. The following characteristics of the patients were recorded: gender, education status, marital status, work status, presence of chronic disease. The changes in best-corrected visual acuity (BCVA) and central macular thickness (CMT) were evaluated at baseline (before treatment) and 1 month after the third intravitreal injection (after treatment). Patients were administered the Turkish form of the National Eye Institute 25-Item Visual Functions Questionnaire (NEI VFQ-25 TR). The quality of life scores assessed by the NEI VFQ-25 TR, the BCVA, intraocular pressure (IOP), and CMT measurements were compared at baseline (before treatment) and 1 month after the third intravitreal injection (after treatment).

RESULTS

We enrolled 52 patients (25 females, 27 males) in our study; mean age was 64.35 ± 9.26 years. After treatment, BCVA improved significantly (p = 0.001), and macular thickness decreased significantly (p < 0.001). All NEI VFQ-25 TR subscale scores were significantly higher after treatment (p < 0.05). However, no significant correlation was found between the change in BCVA and CMT and the change in NEI VFQ-25 TR subscale and composite scores. The increase in near activities scores was significantly higher in males (p = 0.020) and in the retired group (p = 0.022). There were no significant differences in the changes in NEI VFQ-25 TR subscale and composite scores in relation to educational status.

DISCUSSION

Significant improvements in BCVA, macular edema, and vision-related quality of life were found in DME patients who received IVR injections with a loading dose, as shown by the NEI VFQ-25 TR. Interestingly, a significant improvement in quality of life was observed even though the patients could see well with the fellow eye. In conclusion, the NEI VFQ-25 TR is a useful scale to evaluate the changes in visual function and psychosocial characteristics of DME patients after treatment.

KSI-301: antibody biopolymer conjugate in retinal disorders

KSI-301 is a new intravitreal anti-vascular endothelial growth factor (VEGF) antibody biopolymer conjugate under investigation for the treatment of age-related macular degeneration (AMD), diabetic macular oedema (DME) and retinal vein occlusion (RVO). Preclinical and early clinical trials so far have shown promising results in retinal vascular diseases. When using anti-VEGF agents for treatment of retinal disorders, the frequency of injections and follow-up visits has increased the treatment burden, greatly affecting the treatment outcome. There are new anti-VEGF agents in the horizon with extended duration of action, durability, safety profile and efficacy, which seem to address the above issues. PubMed search and Medline search were performed on newer anti-VEGF agents, KSI-301, antibody biopolymer conjugate in retina, KODIAK KSI-301, DAZZLE study, GLEAM study, GLIMMER study, GLOW study and BEACON study. This review article showcases the biophysical properties and ongoing trials related to KSI-301. Moreover, we discuss the efficacy and safety profile of KSI-301 on the basis of the results of available trials.

PHARMACOKINETIC STUDY OF INTRAVITREAL AFLIBERCEPT IN HUMANS WITH NEOVASCULAR AGE-RELATED MACULAR DEGENERATION

PURPOSE

To investigate the half-life of aflibercept in aqueous humor after a single intravitreal injection in patients with neovascular age-related macular degeneration.

METHODS

Prospective, noncomparative, interventional case series of five eyes with neovascular age-related macular degeneration naive to anti-vascular endothelial growth factor therapy were enrolled and treated with intravitreal aflibercept. At baseline, best-corrected visual acuity, optical coherence tomography imaging, and aqueous humor (treatment eye) and blood/plasma samples were taken. Patients underwent best-corrected visual acuity, optical coherence tomography imaging, and sampling of aqueous humor from the eye and blood/plasma at six additional post-treatment time points of 4 hours and Days 1, 3, 7, 14, and 28. Concentrations of aflibercept were quantified using an enzyme-linked immunosorbent assay.

RESULTS

Median peak concentration (Cmax) of free aflibercept in the aqueous was 122 mg/L. The median half-life of free aflibercept was 11 days in the eye. In plasma, the concentrations of free aflibercept were low and transient, reaching undetectable levels during the first week after injection, and undetectable in all patients at time points beyond 7 days.

CONCLUSION

The pharmacokinetic profile in the aqueous humor described here together with the previously reported affinity of aflibercept for vascular endothelial growth factor is consistent with and adds to our understanding for the duration of its clinical efficacy.

Pluripotent Stem Cell-Based Organoid Technologies for Developing Next-Generation Vision Restoration Therapies of Blindness

Blindness, associated with death of retinal cells at the back of the eye, is caused by a number of conditions with high prevalence such as glaucoma, age-related macular degeneration, and diabetic retinopathy. In addition, a large number of orphan inherited (mostly monogenic) conditions, such as retinitis pigmentosa and Leber Congenital Amaurosis, add to the overall number of patients with blinding retinal degenerative diseases. Blindness caused by deterioration and loss of retina is so far incurable. Modern biomedical research leveraging molecular and regenerative medicine approaches had a number of groundbreaking discoveries and proof-of-principle treatments of blindness in animals. However, these methods are slow to be standardized and commercialized as therapies to benefit people losing their eyesight due to retinal degenerative conditions. In this review, we will outline major regenerative medicine approaches, which are emerging as promising for preserving or/and restoring vision. We discuss the potential of each of these approaches to reach commercialization step and be converted to treatments, which could at least ameliorate blindness caused by retinal cell death.

Neovascularization of angle following trabeculectomy augmented with mitomycin-C

The purpose of this study was to report a case of neovascularization of angle (NVA) following trabeculectomy with mitomycin-c (MMC) in a patient with primary open-angle glaucoma. This case report describes a 68-year-old woman who developed NVA and hyphema 2 weeks following an uneventful trabeculectomy with MMC. Trabeculectomy may be associated with serious and vision-threatening complications such as hypotony, suprachoroidal hemorrhage, endophthalmitis, and bleb-related complications. However, neovascularization of the anterior segment is not a commonly reported complication. Neovascularization of the anterior segment is a rare postoperative complication that usually occurs following strabismus or retinal detachment surgeries. The underlying ischemic trigger for anterior segment neovascularization is usually a posterior segment pathology or carotid artery insufficiency. These causative factors were excluded in our patient by lack of any abnormal finding in fundus fluorescein angiography and carotid Doppler ultrasonography. The patient received three subconjunctival bevacizumab injections (1.25 mg/0.1 ml) with frequent topical steroids and showed marked regression of the neovessels. The bleb was functional, and intraocular pressure remained at low teen afterward. NVA following trabeculectomy without any posterior segment or carotid pathologies responded well to subconjunctival bevacizumab and topical steroids.

Growth Factors VEGF-A165 and FGF-2 as Multifunctional Biomolecules Governing Cell Adhesion and Proliferation

Vascular endothelial growth factor-A165 (VEGF-A165) and fibroblast growth factor-2 (FGF-2) are currently used for the functionalization of biomaterials designed for tissue engineering. We have developed a new simple method for heterologous expression and purification of VEGF-A165 and FGF-2 in the yeast expression system of Pichia pastoris. The biological activity of the growth factors was assessed in cultures of human and porcine adipose tissue-derived stem cells (ADSCs) and human umbilical vein endothelial cells (HUVECs). When added into the culture medium, VEGF-A165 stimulated proliferation only in HUVECs, while FGF-2 stimulated the proliferation of both cell types. A similar effect was achieved when the growth factors were pre-adsorbed to polystyrene wells. The effect of our recombinant growth factors was slightly lower than that of commercially available factors, which was attributed to the presence of some impurities. The stimulatory effect of the VEGF-A165 on cell adhesion was rather weak, especially in ADSCs. FGF-2 was a potent stimulator of the adhesion of ADSCs but had no to negative effect on the adhesion of HUVECs. In sum, FGF-2 and VEGF-A165 have diverse effects on the behavior of different cell types, which maybe utilized in tissue engineering.

Exploring the molecular role of endostatin in diabetic neuropathy

For over a decade, diabetic neuropathy has exhibited great emergence in diabetic patients. Though there are numerous impediments in understanding the underlying pathology it is not that enough to conclude. Initially, there was no intricate protocol for diagnosis as its symptoms mimic most of the neurodegenerative disorders and demyelinating diseases. Continuous research on this, reveals many pathological correlates which are also detectable clinically. The most important pathologic manifestation is imbalanced angiogenesis/neo-vascularization. This review is completely focused on established pathogenesis and anti-angiogenic agents which are physiological signal molecules by the origin. Those agents can also be used externally to inhibit those pathogenic pathways. Pathologically DN demonstrates the misbalanced expression of many knotty factors like VEGF, FGF2, TGFb, NF-kb, TNF-a, MMP, TIMP, and many minor factors. Their pathway towards the incidence of DN is quite interrelated. Many anti-angiogenic agents inhibit neovascularization to many extents, but out of them predominantly inhibition of angiogenic activity is shared by endostatin which is now in clinical trial phase II. It inhibits almost all angiogenic factors and it is possible because they share interrelated pathogenesis towards imbalanced angiogenesis. Endostatin is a physiological signal molecule produced by the proteolytic cleavage of collagen XVIII. It has also a broad research profile in the field of medical research and further investigation can show promising therapeutic effects for benefit of mankind.

TOPOGRAPHIC CHANGES IN CHOROIDAL THICKNESS IN AGE-RELATED MACULAR DEGENERATION DURING THE DEVELOPMENT OF ACTIVE CHOROIDAL NEOVASCULARIZATION

PURPOSE

To evaluate topographic changes in choroidal thickness during development of choroidal neovascularization (CNV) in treatment-naive age-related macular degeneration (AMD) and to test the value of such changes as a predictive tool of CNV development.

METHODS

This retrospective cohort included 86 eyes that developed CNV from intermediate AMD, 43 eyes with intermediate AMD, and 36 eyes without AMD. Patients with intermediate AMD underwent spectral domain optical coherence tomography using enhanced depth imaging mode every 6 months until CNV was detected. Choroidal neovascularization was localized to one of the subfields of Early Treatment of Diabetic Retinopathy Study grid on fluorescein angiography. Average choroidal thickness of each subfield was calculated.

RESULTS

Choroidal thickness of the subfield where CNV developed at first clinical detection significantly increased compared with that 6 months before (P = 0.000 for central, P = 0.001 for superior parafoveal, P = 0.002 for temporal parafoveal, P = 0.002 for inferior parafoveal, and P = 0.001 for nasal parafoveal subfield). In eight patients who visited unexpectedly 3 months before CNV development in central subfield, choroidal thickness of central subfield increased significantly compared with that 6 months before CNV development (P = 0.001).

CONCLUSION

Choroidal neovascularization development accompanied choroidal thickening of the corresponding subfield. Regular measurement of choroidal thickness may assist in prediction of CNV.

Binding of Gtf2i-β/δ transcription factors to the ARMS2 gene leads to increased circulating HTRA1 in AMD patients and in vitro

The disease-initiating molecular events for age-related macular degeneration (AMD), a multifactorial retinal disease affecting many millions of elderly individuals worldwide, are still unknown. Of the over 30 risk and protective loci so far associated with AMD through whole genome-wide association studies (GWAS), the Age-Related Maculopathy Susceptibility 2 (ARMS2) gene locus represents one of the most highly associated risk regions for AMD. A unique insertion/deletion (in/del) sequence located immediately upstream of the High Temperature Requirement A1 (HTRA1) gene in this region confers high risk for AMD. Using electrophoretic mobility shift assay (EMSA), we identified that two Gtf2i-β/δ transcription factor isoforms bind to the cis-element 5'- ATTAATAACC-3' contained in this in/del sequence. The binding of these transcription factors leads to enhanced upregulation of transcription of the secretory serine protease HTRA1 in transfected cells and AMD patient-derived induced pluripotent stem cells (iPSCs). Overexpression of Htra1 in mice using a CAG-promoter demonstrated increased blood concentration of Htra1 protein, caused upregulation of vascular endothelial growth factor (VEGF), and produced a choroidal neovascularization (CNV)-like phenotype. Finally, a comparison of 478 AMD patients to 481 healthy, age-matched controls from Japan, India, Australia, and the USA showed a statistically increased level of secreted HTRA1 blood concentration in AMD patients compared with age-matched controls. Taken together, these results suggest a common mechanism across ethnicities whereby increased systemic blood circulation of secreted serine protease HTRA1 leads to subsequent degradation of Bruch's membrane and eventual CNV in AMD.

The Effect of Autogenous Bone Graft Mixed With Recombinant Human Vascular Endothelial Growth Factor on Bone Regeneration

INTRODUCTION

Bone regeneration depends on vascularization in the pertaining site. This study aims to investigate autogenous bone grafts mixed with recombinant human vascular endothelial growth factor (rhVEGF) effect on bone regeneration in rat mandibular bone defect.

MATERIAL METHODS

Using 32 Wistar Albino rats, our experimental study consists of 4 groups: Group1 (control group), the defect was empty; Group 2, autogenous bone graft only; Group 3, gelatin sponge plus rhVEGF applications; Group 4, autogenous bone graft plus rhVEGF applications. The rats were sacrificed on the 28th day after the operation. New bone regeneration was analyzed histologically and immunohistochemically.

RESULTS

Our histological analyses revealed that new bone regeneration in Group 3 was enhanced in comparison to Group 1 and Group 2. However, autogenous bone grafts combined with rhVEGF provided the best outcome in conjunction with the increased remodeling of the new bone.

CONCLUSIONS

In the light of our results, it can be concluded that autogenous bone grafts in combination with rhVEGF can, potentially, enhance neovascularization and bone regeneration.

Role of VEGF-A and LRG1 in Abnormal Angiogenesis Associated With Diabetic Nephropathy

Diabetic nephropathy (DN) is an important public health concern of increasing proportions and the leading cause of end-stage renal disease (ESRD) in diabetic patients. It is one of the most common long-term microvascular complications of diabetes mellitus that is characterized by proteinuria and glomerular structural changes. Angiogenesis has long been considered to contribute to the pathogenesis of DN, whereas the molecular mechanisms of which are barely known. Angiogenic factors associated with angiogenesis are the major candidates to explain the microvascular and pathologic finds of DN. Vascular endothelial growth factor A (VEGF-A), leucine-rich α-2-glycoprotein 1, angiopoietins and vasohibin family signal between the podocytes, endothelium, and mesangium have important roles in the maintenance of renal functions. An appropriate amount of VEGF-A is beneficial to maintaining glomerular structure, while excessive VEGF-A can lead to abnormal angiogenesis. LRG1 is a novel pro-angiogenic factors involved in the abnormal angiogenesis and renal fibrosis in DN. The imbalance of Ang1/Ang2 ratio has a role in leading to glomerular disease. Vasohibin-2 is recently shown to be in diabetes-induced glomerular alterations. This review will focus on current understanding of these angiogenic factors in angiogenesis and pathogenesis associated with the development of DN, with the aim of evaluating the potential of anti-angiogenesis therapy in patients with DN.

Thymosin‑β 4 induces angiogenesis in critical limb ischemia mice via regulating Notch/NF‑κB pathway

Thymosin‑β 4 (Tβ4) has been reported to exert a pro‑angogenic effect on endothelial cells. However, little is known on the role and underlying mechanisms of Tβ4 on critical limb ischemia (CLI). The present study aimed therefore to investigate the mechanisms and pro‑angiogenic effects of Tβ4 in CLI mice. Tβ4 overexpression lentiviral vector was first transfected into HUVEC and CLI mice model, and inhibitors of Notch pathway (DAPT) and NF‑κB pathway (BMS) were also applied to HUVEC and CLI mice. Subsequently, MTT, tube formation and wound healing assays were used to determine the cell viability, angiogenesis and migratory ablity of HUVEC, respectively. Western blotting, reverse transcription, quantitative PCR, immunofluorescence and immunohistochemistry were used to detect the expression of the angiogenesis‑related factors angiopoietin‑2 (Ang2), TEK receptor tyrosine kinase 2 (tie2), vascular endothelial growth factor A (VEGFA), CD31 and α‑smooth muscle actin (α‑SMA) and the Notch/NF‑κB pathways‑related factors NOTCH1 intracellular domain (N1ICD), Notch receptor 3 (Notch3), NF‑κB and p65 in HUVEC or CLI mice muscle tissues. The results demonstrated that Tβ4 not only enhanced the cell viability, angiogenesis and migratory ability of HUVEC but also promoted the expression of Ang2, tie2, VEGFA, N1ICD, Notch3, NF‑κB, and phosphorylated (p)‑p65 in HUVEC. In addition, Tβ4 promoted the expression of CD31, α‑SMA Ang2, tie2, VEGFA, N1ICD and p‑p65 in CLI mice muscle tissues. Treatment with DAPT and BMS had opposite effects of Tβ4, whereas Tβ4 reversed the effect of DAPT and BMS. The findings from the present study suggested that Tβ4 may promote angiogenesis in CLI mice via regulation of Notch/NF‑κB pathways.

Gene expression profile analysis of the rabbit retinal vein occlusion model

The rabbit retinal vein occlusion (RVO) model is an experimental system that mimics retinal ischemic diseases in humans. The rabbit RVO model is widely used to assess the therapeutic efficacy of various experimental surgical procedures. In the present study, we measured temporal retinal expression of Vegfa, which is known as an ischemic response gene, in rabbit RVO. This analysis revealed that the retinal Vegfa transcriptional response began 7 days after generation of RVO, rather than immediately after induction of ischemia. Next, in order to analyze ischemia-induced changes in gene expression profiles, we performed microarray analysis of day 7 RVO retina versus control retina. The angiogenic regulators Dcn and Mmp1 and pro-inflammatory factors Mmp12 and Cxcl13 were significantly upregulated in RVO retinas. Further, we suggest that epigenetic regulation via the REST/cofactor-complex could contribute to RVO pathology. Among human homologous genes in rabbits, genes associated with hypoxia, angiogenesis, and inflammation were significantly upregulated in RVO retinas. Components of the Tumor necrosis factor-alpha (TNFα) and Nuclear factor-kappa B (NF-κB) pathways, which play regulatory roles in angiogenesis and inflammation, were significantly upregulated in RVO, and the expression levels of downstream factors, such as the transcription factor AP-1 and chemokines, were increased. Further, connectivity map analyses suggested that inhibitors of the NF-κB pathway are potential therapeutic agents for retinal ischemic disease. The present study revealed new insights into the pathology of retinal ischemia using the rabbit RVO model, which accurately recapitulates human disease.

Identifying Genetic Risk Factors for Diabetic Macular Edema and the Response to Treatment

Diabetic retinopathy (DR) is the most common microvascular complication of diabetes mellitus (DM). DR is complex and the term encompasses several clinical subtypes of diabetic eye disease, including diabetic macular edema (DME), the most frequent cause of central vision loss in DR patients. Both genetic and environmental factors contribute to the pathophysiology of DR and its subtypes. While numerous studies have identified several susceptibility genes for DR, few have investigated the impact of genetics on DME susceptibility. This review will focus on the current literature surrounding genetic risk factors associated with DME. We will also highlight the small number of studies investigating the genetics of response to antivascular endothelial growth factor (anti-VEGF) injection, which is used to treat DME.

Hydrophobic Interactions Drive Binding between Vascular Endothelial Growth Factor-A (VEGFA) and Polyphenolic Inhibitors

Some polyphenols have been shown to inhibit, at physiological levels, the VEGF-induced VEGF receptor-2 signaling that causes angiogenesis, allegedly by direct interaction with VEGF and reducing the binding to its receptor VEGFR2. Surface plasmon resonance was used to measure the parameters of binding between VEGF and polyphenols as well as the nature of the interactions by assessing the effect of physico-chemical changes in the solution. CD spectrometry was used to determine any change in the secondary structure of the protein upon binding. The kinetic parameters (k_a, k_d, and K_D) that characterise the binding to VEGF were measured for both inhibitor and non-inhibitor polyphenolic molecules. The effect of changes in the physico-chemical conditions of the solution where the binding occurred indicated that the nature of the interactions between VEGF and EGCG was predominantly of a hydrophobic nature. CD studies suggested that a change in the secondary structure of the protein occurred upon binding. Direct interaction and binding between VEGF and polyphenol molecules acting as inhibitors of the signaling of VEGFR2 has been measured for the first time. The binding between VEGF and EGCG seemed to be based on hydrophobic interactions and caused a change in the secondary structure of the protein.

Circulating endothelial and progenitor cells in age-related macular degeneration

PURPOSE

To evaluate circulating endothelial and circulating progenitor cells as biomarkers in age-related macular degeneration patients (both exudative and atrophic forms) in order to establish the possible clinical implication of their assessment.

METHODS

We have enrolled 44 age-related macular degeneration patients: 22 patients with a recently diagnosed exudative (neovascular) form (Group A) and 22 patients with an atrophic (dry) form (Group B). The control group consisted of 22 age and sex-matched healthy subjects (Group C). The number of circulating endothelial progenitor cells (CD34+/KDR+, CD133+/KDR+, and CD34+/KDR+/CD133+), circulating progenitor cells (CD34+, CD133+, and CD34+/CD133+), and circulating endothelial cells were determined in the peripheral venous blood samples by flow cytometry. Neovascular age-related macular degeneration patients were evaluated at baseline and 4 weeks after a loading phase of three consequent intravitreal injections of ranibizumab.

RESULTS

Comparing age-related macular degeneration patients with the control group, endothelial progenitor cell and circulating progenitor cell levels were not significantly different, while age-related macular degeneration patients showed significantly higher levels of circulating endothelial cells (p = 0.001). Anti-vascular endothelial growth factor treatment with intravitreal ranibizumab was associated with a significant reduction of endothelial progenitor cell levels, with no significant influence on circulating progenitor cells and circulating endothelial cells.

CONCLUSION

We reported higher levels of circulating endothelial cells in age-related macular degeneration patients in comparison with the control group, thereby supporting the hypothesis of an involvement of endothelial dysregulation in the age-related macular degeneration and a reduction of the endothelial progenitor cell level in neovascular age-related macular degeneration patients after three intravitreal injections of ranibizumab.

Choroidal Structural Changes Correlate With Neovascular Activity in Neovascular Age Related Macular Degeneration

Purpose

To correlate changes in choroidal thickness and vascularity index with disease activity in patients with neovascular age-related macular degeneration (nAMD).

Methods

Eyes diagnosed with AMD that had two sequential visits within 12 months and that had no choroidal neovascularization (CNV) or had inactive CNV at the first visit were included. Those that had active CNV at follow-up were enrolled as cases. Eyes that did not developed a CNV or that were still inactive at the second visit were enrolled as controls. Disease activity was based on optical coherence tomography (OCT) and fluorescein angiography findings. Subfoveal choroidal thickness (SCT), mean choroidal thickness (MCT), and choroidal vascularity index (CVI) were assessed on enhanced depth imaging OCT and compared between the baseline and follow-up visit. Subgroup analysis accounting for lesion type and previous treatment, if any, were performed.

Results

Sixty-five eyes from 60 patients (35 females) and 50 age- and sex-matched controls were included. At the active visit, cases had an increase from 164 ± 67 μm to 175 ± 70 μm in mean ± SD SCT and from 144 ± 45 μm to 152 ± 45 μm in MCT (both P < 0.0001). The mean CVI also increased at from 54.5% ± 3.3% to 55.4% ± 3.8% (P = 0.04). Controls did not show significant changes in choroidal measurements between the two visits. Mean SCT, MCT, and CVI values were similar for previously treated and treatment-naive eyes.

Conclusions

Choroidal thickness and CVI significantly increased with active disease in nAMD eyes. Changes in choroidal thickness may predict CNV development or recurrence before they are otherwise evident clinically.

Therapeutic Inhibition of VEGF Signaling and Associated Nephrotoxicities

Inhibition of vascular endothelial growth factor A (VEGFA)/vascular endothelial growth factor receptor 2 (VEGFR2) signaling is a common therapeutic strategy in oncology, with new drugs continuously in development. In this review, we consider the experimental and clinical evidence behind the diverse nephrotoxicities associated with the inhibition of this pathway. We also review the renal effects of VEGF inhibition's mediation of key downstream signaling pathways, specifically MAPK/ERK1/2, endothelial nitric oxide synthase, and mammalian target of rapamycin (mTOR). Direct VEGFA inhibition via antibody binding or VEGF trap (a soluble decoy receptor) is associated with renal-specific thrombotic microangiopathy (TMA). Reports also indicate that tyrosine kinase inhibition of the VEGF receptors is preferentially associated with glomerulopathies such as minimal change disease and FSGS. Inhibition of the downstream pathway RAF/MAPK/ERK has largely been associated with tubulointerstitial injury. Inhibition of mTOR is most commonly associated with albuminuria and podocyte injury, but has also been linked to renal-specific TMA. In all, we review the experimentally validated mechanisms by which VEGFA-VEGFR2 inhibitors contribute to nephrotoxicity, as well as the wide range of clinical manifestations that have been reported with their use. We also highlight potential avenues for future research to elucidate mechanisms for minimizing nephrotoxicity while maintaining therapeutic efficacy.

Pharmaceutical Development of AAV-Based Gene Therapy Products for the Eye

A resurgence of interest and investment in the field of gene therapy, driven in large part by advances in viral vector technology, has recently culminated in United States Food and Drug Administration approval of the first gene therapy product targeting a disease caused by mutations in a single gene. This product, LUXTURNA™ (voretigene neparvovec-rzyl; Spark Therapeutics, Inc., Philadelphia, PA), delivers a normal copy of the RPE65 gene to retinal cells for the treatment of biallelic RPE65 mutation–associated retinal dystrophy, a blinding disease. Many additional gene therapy programs targeting both inherited retinal diseases and other ocular diseases are in development, owing to an improved understanding of the genetic basis of ocular disease and the unique properties of the ocular compartment that make it amenable to local gene therapy. Here we review the growing body of literature that describes both the design and development of ocular gene therapy products, with a particular emphasis on target and vector selection, and chemistry, manufacturing, and controls.

Intraocular inflammatory cytokines in patients with neovascular age-related macular degeneration before and after initiation of intravitreal injection of anti-VEGF inhibitor

Age-related macular degeneration (AMD) is a cause of blindness in people older than 50 years. Accumulating evidence indicates the involvement of systemic and local inflammation in the pathogenesis and progression of AMD. Aflibercept is an anti-vascular endothelial growth factor (VEGF) inhibitor, and intravitreal injection of aflibercept (IVA) is the approved treatments of neovascular AMD (nAMD), but the effect on inflammatory response remains unclear. The aim of our study was to investigate the profiles of inflammatory cytokines in the aqueous humor of nAMD patients before and after initiation of IVA. In nAMD patients, IP-10 level was significantly higher and IL-6 level was significantly lower compared with those of cataract patients as controls. Logistic regression analysis identified IP-10 as a positive factor and IL-6 a negative factor associated with the pathogenesis of nAMD. In addition, IP-10 level correlated positively with the mean thickness of macula in the central 1-mm diameter circle. After initiation of IVA, IP-10 level was further elevated, and correlated negatively with VEGF level. These data suggest that IP-10 plays a critical role as an antiangiogenic factor and at the same time an inflammatory factor in the pathogenesis and pathophysiology of nAMD eyes at onset and after IVA initiation.

Comparison of treatment response to intravitreal injection of triamcinolone, bevacizumab and combined form in patients with central retinal vein occlusion: A randomized clinical trial

BACKGROUND

Central retinal vein occlusion (CRVO), is the second-most common disorder after diabetic retinopathy that threatens the vision related to retinal vessels. One of the main reasons of vision loss is CRVO in acute and chronic forms.

OBJECTIVE

The aim of this study was to investigate the response to intravitreal injection of triamcinolone, bevacizumab, and a combined form in patients with CRVO.

METHODS

This study was a double-blinded randomized clinical trial conducted on patients with CRVO who were referred to the ophthalmology clinic of Urmia Imam Khomeini Hospital from May 2015 to May 2016. In total, ninety patients were divided into three groups using random numbers table. The first group received intravitreal triamcinolone acetonide (IVT) for treatment of macular edema due to CRVO, the second group received intravitreal bevacizumab (IVB) and the third group received a combination of IVT and IVB. The best corrected visual acuity (BCVA) and central macular thickness (CMT) were recorded and analyzed using optical coherence tomography system.

RESULTS

In this study a total of 90 eyes were studied, 41 case (45.55%) were male and 49 cases (54.44%) were female. The mean age of patients was 68.41±8.32 years. The mean score of final visual acuity was 0.293±0.11 in the IVT group, 0.25±0.10 in the IVB group and 0.48±0.15 in the IVB+IVT group. The differences between groups considering final visual acuity was significant (p<0.001). The mean thickness of final macular was 383.33±97.70 micrometer in IVT group, 386.33±136.79 micrometers in IVB group and 307.33±110.79 micrometers in IVT+IVB group which were significant (p=0.014).

CONCLUSION

Using a combination of bevacizumab and triamcinolone in the treatment of central retinal vein occlusion compared with using each of them separately, had a better result and can be used as a solution in this disease.

TRIAL REGISTRATION

The trial was registered at the Thai Registry of Clinical Trials (http://www.clinicaltrials.in.th) with the TCTR ID: TCTR20170612005.

FUNDING

The authors received no financial support for the research, authorship, and/or publication of this article.

Oxalomalate reduces expression and secretion of vascular endothelial growth factor in the retinal pigment epithelium and inhibits angiogenesis: Implications for age-related macular degeneration

Clinical and experimental observations indicate a critical role for vascular endothelial growth factor (VEGF), secreted by the retinal pigment epithelium (RPE), in pathological angiogenesis and the development of choroidal neovascularization (CNV) in age-related macular degeneration (AMD). RPE-mediated VEGF expression, leading to angiogenesis, is a major signaling mechanism underlying ocular neovascular disease. Inhibiting this signaling pathway with a therapeutic molecule is a promising anti-angiogenic strategy to treat this disease with potentially fewer side effects. Oxalomalate (OMA) is a competitive inhibitor of NADP⁺-dependent isocitrate dehydrogenase (IDH), which plays an important role in cellular signaling pathways regulated by reactive oxygen species (ROS). Here, we have investigated the inhibitory effect of OMA on the expression of VEGF, and the associated underlying mechanism of action, using in vitro and in vivo RPE cell models of AMD. We found that OMA reduced the expression and secretion of VEGF in RPE cells, and consequently inhibited CNV formation. This function of OMA was linked to its capacity to activate the pVHL-mediated HIF-1α degradation in these cells, partly via a ROS-dependent ATM signaling axis, through inhibition of IDH enzymes. These findings reveal a novel role for OMA in inhibiting RPE-derived VEGF expression and angiogenesis, and suggest unique therapeutic strategies for treating pathological angiogenesis and AMD development.

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Oxalomalate reduces VEGF expression in RPE cells by promoting HIF-1α degradation.

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Oxalomalate activates pVHL-mediated HIF-1α degradation by regulation of ATM-Chk2-E2F1 axis.

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Inhibition of IDH enzymes by oxalomalate activates ROS-mediated ATM signaling axis.

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Oxalomalate inhibits CNV-related angiogenesis in in vivo mouse model of AMD.

Aflibercept as First-Line Therapy in Patients with Treatment-Naïve Neovascular Age-Related Macular Degeneration: Prospective Case Series Analysis in Real-Life Clinical Practice

PURPOSE

To assess the 13-month effectiveness and safety of aflibercept in naïve patients with neovascular age-related macular degeneration (nvAMD) in a real-life clinical setting.

METHODS

Thirty-two treatment-naïve patients with nvAMD participated in a prospective two-center study. Patients received intravitreal injections of aflibercept (Eylea®), a loading dose of three monthly injections (2 mg/0.05 ml) every 4 weeks for the first 3 months, followed by intravitreal injections every 2 months.

RESULTS

At 3 and 13 months, the mean best-corrected visual acuity improved significantly as compared with baseline (logMAR 0.53 ± 0.30 and 0.55 ± 0.32 vs. 0.30 ± 0.24, respectively, p < 0.001). At 3 and 13 months, 46.8% of patients (15/32) gained ≥15 ETDRS letters. The mean decrease in central macular thickness was also significant at 3 months (252 ± 35 µm) and at 13 months (249 ± 38 µm) as compared with pretreatment values (383 ± 76 µm) (p < 0.01). Also, 50% resolution of pigment epithelial detachment (PED) was observed in 8 out of 9 eyes (88.9%) with PED at baseline. Intravitreal injections were well tolerated and no adverse events were recorded.

CONCLUSION

Aflibercept was effective and safe for treating nvAMD in naïve patients in routine daily practice.

Subfoveal choroidal thickness changes after intravitreal bevacizumab injection for neovascular age-related macular degeneration and diabetic macular edema

The purpose of this study was to investigate the changes in subfoveal choroidal thickness (SFCT) after intravitreal injection of bevacizumab (IVB) for neovascular age-related macular degeneration (AMD) and diabetic macular edema (DME). This retrospective, consecutive, interventional case series study included 43 eyes [21 affected eyes with neovascular AMD (AMD group) and 22 affected eyes with DME (DME group)] which were treated with 1.25 mg/0.5 ml IVB and 43 untreated fellow eyes of 43 patients. SFCT was measured in all 86 eyes at baseline before IVB injection and at day 1, week 1, and month 1 after injection by use of enhanced depth imaging optical coherence tomography (EDI OCT). Central foveal thickness (CFT) and best-corrected visual acuity were analyzed at baseline and during follow-up visits. Main outcome measure was change in SFCT in 1 month after treatment. All 43 eyes treated with IVB showed a significant reduction in SFCT. Mean SFCT in treated eyes decreased from 237.1 ± 75.3 µm at baseline to 214.0 ± 65.7 µm at day 1, 205.4 ± 59.7 at week 1, and 222.7 ± 73.3 at month 1, whereas SFCT in fellow eyes changed from 228.4 ± 63.6 at baseline to 224.5 ± 68.5 at day 1, 220.4 ± 72.1 at week 1, and 226.9 ± 74.0 at month 1. SFCT demonstrated a similar trend toward decrease in both groups. CFT decreased significantly and visual acuity improved significantly. SFCT decreased significantly in AMD and DME eyes following injection. The decreasing effect of bevacizumab on choroidal thickness was highest at first week and continued to the end of first month after injection.

[Vascular endothelial growth factors (VEGF): role in pathological processes]

Russian and foreign literature sources on vascular endothelial growth factors (VEGF) from different parts of the human body, their prevalence and involvement in pathological processes were analyzed. A conclusion has been drawn that further research on different types of VEGF is needed.

Spectral domain optical coherence tomographic analysis of healthy retina in branch retinal vein occlusion and its response to antiangiogenic therapy

PURPOSE

To propose a model that measures the effect of intravitreal bevacizumab (IVB) on relatively healthy retina. The purpose is to analyze the remote effect of a branch retinal vein occlusion in the healthy retina, to determine the response it may have to IVB, and to determine if IVB has an atrophic effect on the healthy retina.

METHODS

Retrospective, longitudinal comparative analysis of patients with branch retinal vein occlusion treated with IVB. Eyes were divided into experimental (branch retinal vein occlusion eye) and control (contralateral eye) groups. Each eye was analyzed for thickness and area. Thickness measurements were performed for total retinal thickness, inner retina thickness, and outer retina thickness. Area was measured for photoreceptors, choroid, and total retina.

RESULTS

Eighteen eyes of 9 patients. For thickness analysis, 1,050 scans were studied, and 126 measurements were performed on 42 scans for area analysis. No difference was observed for thickness, except for inner retina thickness. No difference was observed for area. No difference was observed when analyzing a cumulative exposure to IVB.

CONCLUSION

There is no evidence to suggest an atrophic effect caused by IVB when analyzing thickness or area in this experiment. This model could be used to analyze the long-term safety of IVB in larger studies.

Induction of VEGFA mRNA translation by CoCl2 mediated by HuR

Vascular endothelial growth factor (VEGF) A is a master regulator of neovascularization and angiogenesis. VEGFA is potently induced by hypoxia and by pathological conditions including diabetic retinopathy and tumorigenesis. Fine-tuning of VEGFA expression by different stimuli is important for maintaining tissue vascularization and organ homeostasis. Here, we tested the effect of the hypoxia mimetic cobalt chloride (CoCl2) on VEGFA expression in human cervical carcinoma HeLa cells. We found that CoCl2 increased the levels of VEGFA mRNA and VEGFA protein without affecting VEGFA mRNA stability. Biotin pulldown analysis to capture the RNA-binding proteins (RBPs) bound to VEGFA mRNA followed by mass spectrometry analysis revealed that the RBP HuR [human antigen R, a member of the embryonic lethal abnormal vision (ELAV) family of proteins], interacts with VEGFA mRNA. VEGFA mRNA-tagging experiments showed that exposure to CoCl2 increases the interaction of HuR with VEGFA mRNA and promoted the colocalization of HuR and the distal part of the VEGFA 3'-untranslated region (UTR) in the cytoplasm. We propose that under hypoxia-like conditions, HuR enhances VEGFA mRNA translation.

Complications of intravitreal injections in patients with diabetes

Intravitreal injections for the treatment of retinal disorders and intraocular infection have become a common ophthalmic procedure, and injections of anti-vascular endothelial growth factor agents or steroids are frequently performed for the treatment of diabetic macular edema or other diabetic vascular pathology. Diabetic patients may be at higher risk of adverse events than non-diabetic individuals given frequent systemic co-morbidities, such as cardiovascular and renal disease, susceptibility to infection, and unique ocular pathology that includes fibrovascular proliferation. Fortunately, many associated complications, including endophthalmitis, are related to the injection procedure and can therefore be circumvented by careful attention to injection techniques. This review highlights the safety profile of intravitreal injections in patients with diabetes. Although diabetic patients may theoretically be at higher risk than non-diabetic patients for complications, a comprehensive review of the literature does not demonstrate substantial increased risk of intravitreal injections in patients with diabetes.

Oxidative stress, insulin resistance, dyslipidemia and type 2 diabetes mellitus

Oxidative stress is increased in metabolic syndrome and type 2 diabetes mellitus (T2DM) and this appears to underlie the development of cardiovascular disease, T2DM and diabetic complications. Increased oxidative stress appears to be a deleterious factor leading to insulin resistance, dyslipidemia, β-cell dysfunction, impaired glucose tolerance and ultimately leading to T2DM. Chronic oxidative stress, hyperglycemia and dyslipidemia are particularly dangerous for β-cells from lowest levels of antioxidant, have high oxidative energy requirements, decrease the gene expression of key β-cell genes and induce cell death. If β-cell functioning is impaired, it results in an under production of insulin, impairs glucose stimulated insulin secretion, fasting hyperglycemia and eventually the development of T2DM.

Intraoperative fluorescein angiography-guided treatment in children with early Coats' disease

PURPOSE

To review the anatomic and visual outcomes of a series of children diagnosed with Coats' disease and treated on the basis of intraoperative fluorescein angiography (FA) findings.

DESIGN

Retrospective case series.

PARTICIPANTS

Twenty-five children 2 to 15 years of age diagnosed with early Coats' disease and treated after intraoperative FA.

METHODS

Retrospective review of patients who underwent treatment for stage 2 Coats' disease in a tertiary center in the United Kingdom between 2007 and 2012. The children underwent treatment to the telangiectatic vessels and associated areas of retinal nonperfusion identified on intraoperative FA performed with a wide-angle retinal camera (RetCam II).

MAIN OUTCOME MEASURES

Anatomic and structural assessment of the retina after treatment, visual acuity (VA), and complications related to treatment.

RESULTS

Twenty children with Coats' disease who underwent intraoperative RetCam FA and retinal ablative treatment and who had more than 3 months of follow-up were identified from clinical records. All had unilateral disease. Six eyes were classified as stage 2a, and 14 eyes were classified as stage 2b. The median duration of follow-up was 21 months (mean, 26 months). Fifteen eyes needed 1 treatment to stabilize the disease, and 5 eyes needed a second treatment. None of the patients demonstrated progression of the disease to a more severe stage. Twelve eyes had a final VA of 0.4 logarithm of the minimum angle of resolution (logMAR) or better, 6 patients had VA between 0.4 and 1.0 logMAR, and 2 patients had VA worse than 1.0 logMAR.

CONCLUSIONS

The treatment of retinal telangiectasia and areas of retinal nonperfusion identified by wide-angle intraoperative FA in children with stage 2 Coats' disease led to good anatomic outcome, with preservation of VA in most cases.