Inflammatory mediators and angiogenic factors in choroidal neovascularization: pathogenetic interactions and therapeutic implications

Natural products for the treatment of age-related macular degeneration

BACKGROUND

Age-related macular degeneration (AMD) is a chronic retinal disease that significantly influences the vision of the elderly.

PURPOSE

There is no effective treatment and prevention method. The pathogenic process behind AMD is complex, including oxidative stress, inflammation, and neovascularization. It has been demonstrated that several natural products can be used to manage AMD, but systematic summaries are lacking.

STUDY DESIGN AND METHODS

PubMed, Web of Science, and ClinicalTrials.gov were searched using the keywords "Biological Products" AND "Macular Degeneration" for studies published within the last decade until May 2023 to summarize the latest findings on the prevention and treatment of age-related macular degeneration through the herbal medicines and functional foods.

RESULTS

The eligible studies were screened, and the relevant information about the therapeutic action and mechanism of natural products used to treat AMD was extracted. Our findings demonstrate that natural substances, including retinol, phenols, and other natural products, prevent the development of new blood vessels and protect the retina from oxidative stress in cells and animal models. However, they have barely been examined in clinical studies.

CONCLUSION

Natural products could be highly prospective candidate drugs used to treat AMD, and further preclinical and clinical research is required to validate it to control the disease.

The matricellular protein CCN5 prevents anti-VEGF drug-induced epithelial-mesenchymal transition of retinal pigment epithelium

Age-related macular degeneration (AMD) is one of the major causes of blindness in the elderly worldwide. Anti-vascular endothelial growth factor (VEGF) drugs have been widely used to treat the neovascular type of AMD (nAMD). However, VEGF acts not only as a pro-angiogenic factor but also as an anti-apoptotic factor in the eyes. In this study, we found that anti-VEGF drugs, including bevacizumab (Bev), ranibizumab (Ran), and aflibercept (Afl), induced epithelial-mesenchymal transition (EMT) in ARPE-19 cells in vitro, accompanied by the induction of CCN2, a potent pro-fibrotic factor. Similarly, intravitreal injection of Afl into mouse eyes resulted in EMT in the retinal pigmented epithelium (RPE). Co-treatment with CCN5, an anti-fibrotic factor that down-regulates CCN2 expression, significantly attenuated the adverse effects of the anti-VEGF drugs both in vitro and in vivo. Inhibition of the VEGF signaling pathway with antagonists of VEGF receptors, SU5416 and ZM323881, induced EMT and up-regulated CCN2 in ARPE-19 cells. Additionally, knock-down of CCN2 with siRNA abolished the adverse effects of the anti-VEGF drugs in ARPE-19 cells. Collectively, these results suggest that anti-VEGF drugs induce EMT in RPE through the induction of CCN2 and that co-treatment with CCN5 attenuates the adverse effects of anti-VEGF drugs in mouse eyes.

The structure and function of the human choroid

In this manuscript, the structure of the human choroid is reviewed with emphasis of the macro- and microscopic anatomy including Bruch's membrane, choriocapillaris, Sattler's and Haller's layer, and the suprachoroid. We here discuss the development of the choroid, as well as the question of choroidal lymphatics, and further the neuronal control of this tissue, as well as the pathologic angiogenesis. Wherever possible, functional aspects of the various structures are included and reviewed.

Pirfenidone: A Promising Drug in Ocular Therapeutics

Pirfenidone, initially indicated for lung fibrosis, has gone beyond its original purpose, and shown promise in eye care. This detailed review tracks its evolution from lung treatment to aiding eye healing as evidenced by published literature. Pirfenidone's multifaceted attributes extend to mitigating corneal fibrosis, inflammation, and trauma. Through rigorous investigations, its efficacy emerges in diabetic retinopathy, macular degeneration, and postoperative glaucoma interventions. As an unheralded protagonist, pirfenidone reshapes ocular care paradigms, inviting renewed research opportunities.

Treatment Strategies for Anti-VEGF Resistance in Neovascular Age-Related Macular Degeneration by Targeting Arteriolar Choroidal Neovascularization

Despite extensive use of intravitreal anti-vascular endothelial growth factor (anti-VEGF) biologics for over a decade, neovascular age-related macular degeneration (nAMD) or choroidal neovascularization (CNV) continues to be a major cause of irreversible vision loss in developed countries. Many nAMD patients demonstrate persistent disease activity or experience declining responses over time despite anti-VEGF treatment. The underlying mechanisms of anti-VEGF resistance are poorly understood, and no effective treatment strategies are available to date. Here we review evidence from animal models and clinical studies that supports the roles of neovascular remodeling and arteriolar CNV formation in anti-VEGF resistance. Cholesterol dysregulation, inflammation, and ensuing macrophage activation are critically involved in arteriolar CNV formation and anti-VEGF resistance. Combination therapy by neutralizing VEGF and enhancing cholesterol removal from macrophages is a promising strategy to combat anti-VEGF resistance in CNV.

Use of Optical Coherence Tomography and Optical Coherence Tomography Angiography in the Diagnosis and Follow-Up of Endogenous Candida Endophthalmitis: A Case Report

Background: Endogenous Candida endophthalmitis (ECE) is a rare but sight-threatening disease. Patients with ECE present with various clinical signs and symptoms, which can complicate the diagnosis. The aim of this report was to demonstrate the outcomes of treatment and to diagnose macular complications caused by intraocular inflammation. Case presentation: A 41-year-old woman with a history of acute intermittent porphyria presented with a progressive vision loss in her left eye. Left-eye OCT revealed findings consistent with a fungal etiology, which was confirmed by the culture of swabs collected from a central vein catheter. The outcomes of intravenous fluconazole treatment were not satisfactory, and the patient developed recurrent attacks of porphyria, suggesting a porphyrogenic effect of systemic antifungal therapy. Repeated intravitreal injections with amphotericin B led to a gradual regression of inflammatory lesions. However, follow-up examinations revealed active macular neovascularization (MNV) on both OCT and OCTA scans. The patient was administered intravitreal bevacizumab. At the 11th month of follow-up, OCT and OCTA scans showed significant inflammatory lesions regression with macula scarring, and no MNV activity was detected. Conclusions: This case highlights the importance of OCT and OCTA as valuable noninvasive imaging techniques for the identification of ECE, the monitoring of its clinical course, and the diagnosis of macular complications.

Analysis of ocular fluid in patients with ranibizumab-recalcitrant neovascular age-related macular degeneration who have serum anti-ranibizumab antibodies

PURPOSE

To evaluate whether anti-drug antibodies (ADAs) are present in the ocular fluid of patients with ranibizumab-recalcitrant neovascular age-related macular degeneration (nAMD).

METHODS

Two serum ADA-positive ranibizumab-recalcitrant patients and two serum ADA-negative controls were recruited from patients with nAMD treated with ranibizumab monotherapy. Recalcitrance was defined as persistent fluid after ≥6 monthly ranibizumab injections. Serum and aqueous humor ADAs were detected by enzyme-linked immunosorbent assay and immunoprecipitation, respectively.

RESULTS

Two of 156 ranibizumab-treated patients were ADA-positive. The patients received six and 14 ranibizumab injections, respectively, up to 4 weeks prior to blood collection. The serum ADA concentration was estimated to be approximately 50,000 ng/mL. Neutralizing ADAs were confirmed in both samples. A specific band was detected by immunoprecipitation only in ADA-positive samples, consistent with the results of enzyme-linked immunosorbent assay. Based on an assessment of the degree of sensitivity of commercially available anti-ranibizumab antibodies, it was estimated that the immunoprecipitation method could detect ADA levels >30 ng. Nevertheless, ADAs were not detected in the aqueous humor of either the experimental or control group.

CONCLUSION

In the aqueous humor, ADAs are either not present or are present at a lower concentration than that which can be detected by immunoprecipitation. This presumably reflects the fact that blood ADA is the product of systemic circulation clearance through anterior elimination of intravitreal ranibizumab. Based on our results, ADAs do not return to the eye in sufficient quantities to interfere with the action of ranibizumab in the vitreous cavity.

Pharmacological Modulation of β-Catenin Preserves Endothelial Barrier Integrity and Mitigates Retinal Vascular Permeability and Inflammation

Compromised blood-retinal barrier (BRB) integrity is a significant factor in ocular diseases like uveitis and retinopathies, leading to pathological vascular permeability and retinal edema. Adherens and tight junction (AJ and TJ) dysregulation due to retinal inflammation plays a pivotal role in BRB disruption. We investigated the potential of ICG001, which inhibits β-catenin-mediated transcription, in stabilizing cell junctions and preventing BRB leakage. In vitro studies using human retinal endothelial cells (HRECs) showed that ICG001 treatment improved β-Catenin distribution within AJs post lipopolysaccharide (LPS) treatment and enhanced monolayer barrier resistance. The in vivo experiments involved a mouse model of LPS-induced ocular inflammation. LPS treatment resulted in increased albumin leakage from retinal vessels, elevated vascular endothelial growth factor (VEGF) and Plasmalemmal Vesicle-Associated Protein (PLVAP) expression, as well as microglia and macroglia activation. ICG001 treatment (i.p.) effectively mitigated albumin leakage, reduced VEGF and PLVAP expression, and reduced the number of activated microglia/macrophages. Furthermore, ICG001 treatment suppressed the surge in inflammatory cytokine synthesis induced by LPS. These findings highlight the potential of interventions targeting β-Catenin to enhance cell junction stability and improve compromised barrier integrity in various ocular inflammatory diseases, offering hope for better management and treatment options.

Apolipoprotein ε in Brain and Retinal Neurodegenerative Diseases

Alzheimer's disease (AD) is the most common form of dementia that remains incurable and has become a major medical, social, and economic challenge worldwide. AD is characterized by pathological hallmarks of senile plaques (SP) and neurofibrillary tangles (NFTs) that damage the brain up to twenty years before a clinical diagnosis is made. Interestingly these pathological features have also been observed in retinal neurodegenerative diseases including age related macular degeneration (ARMD), glaucoma and diabetic retinopathy (DR). An association of AD with these diseases has been suggested in epidemiological studies and several common pathological events and risk factors have been identified between these diseases. The E4 allele of Apolipoprotein E (APOE) is a well-established genetic risk factor for late onset AD. The ApoE ε4 allele is also associated with retinal neurodegenerative diseases however in contrast to AD, it is considered protective in AMD, likewise ApoE E2 allele, which is a protective factor for AD, has been implicated as a risk factor for AMD and glaucoma. This review summarizes the evidence on the effects of ApoE in retinal neurodegenerative diseases and discusses the overlapping molecular pathways in AD. The involvement of ApoE in regulating amyloid beta (Aβ) and tau pathology, inflammation, vascular integrity, glucose metabolism and vascular endothelial growth factor (VEGF) signaling is also discussed.

Roles of Histone Acetyltransferases and Deacetylases in the Retinal Development and Diseases

The critical role of epigenetic modification of histones in maintaining the normal function of the nervous system has attracted increasing attention. Among these modifications, the level of histone acetylation, modulated by histone acetyltransferases (HATs) and histone deacetylases (HDACs), is essential in regulating gene expression. In recent years, the research progress on the function of HDACs in retinal development and disease has advanced remarkably, while that regarding HATs remains to be investigated. Here, we overview the roles of HATs and HDACs in regulating the development of diverse retinal cells, including retinal progenitor cells, photoreceptor cells, bipolar cells, ganglion cells, and Müller glial cells. The effects of HATs and HDACs on the progression of various retinal diseases are also discussed with the highlight of the proof-of-concept research regarding the application of available HDAC inhibitors in treating retinal diseases.

Choroidal Structural Alterations and Choroidal Vascularity Index in Bipolar Disorder Patients

PURPOSE

The aim of this study was to compare bipolar disorder (BD) patients with age- and sex-matched healthy individuals in order to assess the choroidal structural alterations, retinal nerve fiber layer (RNFL) thickness, and retinal changes in BD patients using encanhed depth imaging optic coherence tomography (EDI-OCT).

METHOD

For this research, 39 eyes of BD patients and 36 eyes of age-matched healthy volunteers were used. Five locations were used to assess the choroidal thickness (CT): subfoveal, 500 µm nasal and 1500 µm nasal to the fovea, 500 µm temporal and 1500 µm temporal to the fovea. Image-J was used to determine the total choroidal area (TCA), luminal area (LA), and choroidal vascularity index (CVI). The Spectralis-OCT device was used to evaluate the central macular thickness (CMT), retinal nerve fiber layer (RNFL), and ganglion cell layer (GCL). The data were statistically compared.

RESULTS

BD patients had significantly decreased subfoveal, nasal, and temporal CTs than controls (for all three, p = 0.0001). The results of CMT and GCL were found to be thinner than controls. (for all p=0.0001) In comparison to the controls, the mean TCA and LA were decreased in the BD group. (p=0.0001, p=0.0001  respectively,).  Between the RNFL and CVI values in the BD and control groups, there was no statistically significant difference (p>0.05).

CONCLUSION

The results of this investigation showed that the retina and choroid of patients with BD had considerable anatomical changes.

Genetic deficiency and pharmacological modulation of RORα regulate laser-induced choroidal neovascularization

Choroidal neovascularization (CNV) causes acute vision loss in neovascular age-related macular degeneration (AMD). Genetic variations of the nuclear receptor RAR-related orphan receptor alpha (RORα) have been linked with neovascular AMD, yet its specific role in pathological CNV development is not entirely clear. In this study, we showed that Rora was highly expressed in the mouse choroid compared with the retina, and genetic loss of RORα in Staggerer mice (Rorasg/sg) led to increased expression levels of Vegfr2 and Tnfa in the choroid and retinal pigment epithelium (RPE) complex. In a mouse model of laser-induced CNV, RORα expression was highly increased in the choroidal/RPE complex post-laser, and loss of RORα in Rorasg/sg eyes significantly worsened CNV with increased lesion size and vascular leakage, associated with increased levels of VEGFR2 and TNFα proteins. Pharmacological inhibition of RORα also worsened CNV. In addition, both genetic deficiency and inhibition of RORα substantially increased vascular growth in isolated mouse choroidal explants ex vivo. RORα inhibition also promoted angiogenic function of human choroidal endothelial cell culture. Together, our results suggest that RORα negatively regulates pathological CNV development in part by modulating angiogenic response of the choroidal endothelium and inflammatory environment in the choroid/RPE complex.

Decreased Expression of Soluble Epoxide Hydrolase Suppresses Murine Choroidal Neovascularization

Neovascular or "wet" age-related macular degeneration (nAMD) is a leading cause of blindness among older adults. Choroidal neovascularization (CNV) is a major pathological feature of nAMD, in which abnormal new blood vessel growth from the choroid leads to irreversible vision loss. There is a critical need to develop novel therapeutic strategies to address limitations of the current anti-vascular endothelial growth factor biologics. Previously, we identified soluble epoxide hydrolase (sEH) as a possible therapeutic target for CNV through a forward chemical genetic approach. The purpose of this study was to validate sEH as a target by examining retinal expression of sEH protein and mRNA by immunohistochemistry and RNAscope in situ hybridization, respectively, and to assess the efficacy of an adeno-associated virus (AAV) vector designed to knock down the sEH gene, Ephx2, in the murine laser-induced (L-) CNV model. nAMD patient postmortem eye tissue and murine L-CNV showed overexpression of sEH in photoreceptors and retinal pigment epithelial cells. Ephx2 knockdown significantly reduced CNV and normalized mRNA expression levels of CNV-related inflammatory markers. Thus, this study further establishes sEH as a promising therapeutic target against CNV associated with nAMD.

Effect of Nintedanib Nanothermoreversible Hydrogel on Neovascularization in an Ocular Alkali Burn Rat Model

PURPOSE

To compare the therapeutic effects of different forms of nintedanib ophthalmic preparations on neovascularization corneal alkali burns in rats.

METHODS

Forty rat models of left eye corneal alkali burns were constructed, and the five groups (N = 8) were treated with normal saline, dexamethasone ointment (dexamethasone), 0.2% nintedanib aqueous solution and nintedanib nano thermoreversible hydrogel (NNTH). A slit lamp microscope was used to observe the area of neovascularization. The levels of the inflammatory factors were detected by ELISA. HE staining was performed on the rat corneas. Vascular endothelial growth factor (VEGFA) was detected by immunohistochemistry, and the expression of corneal VEGFA and CD31 was detected by western blotting. An MTT assay was performed to detect the cytotoxicity of nintedanib on human corneal epithelial cells (HCECs) and human umbilical vein vascular endothelial cells (HUVECs). Cell migration was detected by a cell scratch assay, and the proportion of apoptotic cells was detected by Annexin/PI double staining. Immunofluorescence and western blotting were performed to detect the protein expression of VEGFA and CD31.

RESULTS

NNTH had a stronger inhibitory effect on corneal neovascularization (CNV) in alkali-burned rats while reducing the level of inflammatory factors. NNTH had a longer drug duration of release than nanoformulations in vitro. Nintedanib at low concentrations (<8 μM) had no significant cytotoxicity to HCECs but significantly induced apoptosis and inhibited the expression of VEGFA and CD31 and the migration of HUVECs.

CONCLUSIONS

Nanomorphic thermoreversible hydrogel is superior among the nintedanib ophthalmic preparations, showing better inhibition of CNV in alkali-burned eyeballs and it blocked the migration and proangiogenic ability of HUVECs.

Absence of Gut Microbiota Is Associated with RPE/Choroid Transcriptomic Changes Related to Age-Related Macular Degeneration Pathobiology and Decreased Choroidal Neovascularization

Studies have begun to reveal significant connections between the gut microbiome and various retinal diseases, including age-related macular degeneration (AMD). As critical supporting tissues of the retina, the retinal pigment epithelium (RPE) and underlying choroid play a critical role in retinal homeostasis and degeneration. However, the relationship between the microbiome and RPE/choroid remains poorly understood, particularly in animal models of AMD. In order to better elucidate this role, we performed high-throughput RNA sequencing of RPE/choroid tissue in germ-free (GF) and specific pathogen-free (SPF) mice. Furthermore, utilizing a specialized laser-induced choroidal neovascularization (CNV) model that we developed, we compared CNV size and inflammatory response between GF and SPF mice. After correction of raw data, 660 differentially expressed genes (DEGs) were identified, including those involved in angiogenesis regulation, scavenger and cytokine receptor activity, and inflammatory response-all of which have been implicated in AMD pathogenesis. Among lasered mice, the GF group showed significantly decreased CNV lesion size and microglial infiltration around CNV compared to the SPF group. Together, these findings provide evidence for a potential gut-RPE/choroidal axis as well as a correlation with neovascular features of AMD.

Sex-Specific Changes in Choroid Vasculature Among Patients with Schizophrenia and Bipolar Disorder

Purpose

While structural changes within the retina of psychosis patients have been established, no detailed studies of choroidal microvasculature in these patients have been performed. Given evidence of microvascular disruption in psychosis patients, this study sought to determine whether there exists evidence of microvascular disruption in the choroids in these patients.

Methods

Fifty-six subjects (20 controls and 36 psychosis patients) were recruited from April 2018 to February 2020. Five were excluded due to imaging artifact or missing demographic information. Swept-source optical coherence tomography angiography (SS-OCTA) images were obtained. Choroid vascular enface images (12 mm × 9mm) were exported every 2.6 μm from Bruch’s membrane to the choroid–scleral interface from Topcon to ImageJ. The images were binarized using Otsu’s method, signal from the optic disk and retinal vasculature was removed, and average choroid vascular density (CVD) was calculated as the average of percent area occupied by choroidal vasculature across images in the stack. Choroid vascular volume (CVV) was calculated as the CVD multiplied by maximum CT and image area. During image analysis, study staff were blinded to the phenotype of the study subjects.

Results

Compared with same-sex controls, male psychiatric patients had significantly lower CVD. Compared with same-sex controls, female psychiatric patients had significantly lower maximum CT with correspondingly decreased CVV, after adjusting for age. When all psychiatric patients were compared with all healthy controls, no significant differences in CT, CVD, or CVV were noted.

Conclusion

These results suggest that the pathogenesis of psychotic illness affects choroidal microvasculature in a sex-specific manner.

The Anti-Inflammatory Effect of Hydrogen Gas Inhalation and Its Influence on Laser-Induced Choroidal Neovascularization in a Mouse Model of Neovascular Age-Related Macular Degeneration

Background: Age-related macular degeneration (AMD) is a leading cause of blindness in the elderly. Choroidal neovascularization (CNV) is the major pathologic feature of neovascular AMD. Oxidative damages and the ensuing chronic inflammation are representative of trigger events. Hydrogen gas (H₂) has been demonstrated as an antioxidant and plays a role in the regulation of oxidative stress and inflammation. This experiment aimed to investigate the influence of H₂ inhalation on a mouse model of CNV. Methods: Laser was used to induce CNV formation. C57BL/6J mice were divided into five groups: the control group; the laser-only group; and the 2 h, 5 h, and 2.5 h/2.5 h groups that received laser and H₂ inhalation (21% oxygen, 42% hydrogen, and 37% nitrogen mixture) for 2 h, 5 h, and 2.5 h twice every day, respectively. Results: The severity of CNV leakage on fluorescence angiography showed a significant decrease in the H₂ inhalation groups. The mRNA expression of hypoxia-inducible factor 1 alpha and its immediate downstream target vascular endothelial growth factor (VEGF) showed significant elevation after laser, and this elevation was suppressed in the H₂ inhalation groups in an inhalation period length-related manner. The mRNA expression of cytokines, including tumor necrosis factor alpha and interlukin-6, also represented similar results. Conclusion: H₂ inhalation could alleviate CNV leakage in a laser-induced mouse CNV model, and the potential mechanism might be related to the suppression of the inflammatory process and VEGF-driven CNV formation.

Inflammatory Choroidal Neovascular Membranes: Clinical Profile, Treatment Effectiveness, and Visual Prognosis

Purpose

To characterise a sample of patients with inflammatory choroidal neovascularization (I-CNV), including clinical profile, underlying aetiology and its course, treatments performed, associated clinical response, and visual prognosis.

Methods

Retrospective analysis of patients with a diagnosis of I-CNV followed at the Ophthalmology Department of Centro Hospitalar Universitário de São João (CHUSJ). Clinical and visual outcomes were classified according to the difference in visual acuity after treatment.

Results

Twenty eyes from 17 patients were analysed (11 female and 6 male patients, mean age 41.90 ± 16.457 years at CNV diagnosis). Punctate inner choroidopathy/multifocal choroiditis was the predominant inflammatory aetiology (10 patients, 58.82%). Median follow-up time was 46 months (range 10 to 188 months). Neovascularization was treated with intravitreal anti-VEGF injections (bevacizumab, aflibercept, and ranibizumab), and inflammation with anti-inflammatory/immunosuppressive therapy (oral, intravenous, and/or intravitreal corticosteroids; oral cyclosporine or methotrexate). Intravitreal anti-VEGF agents had a median number of 7.00 injections (IQR, 4.25 to 29.00). Visual acuity among 20 eyes had a mean gain of 15.10 ± 12.998 ETDRS letters after anti-VEGF treatment (p=0.000051). According to our classification, 16 had an improved outcome (80.00%), 3 had a stable outcome (15.00%), and 1 had a worsened visual outcome (5.00%). In addition, 13 eyes (65.00%) had a final VA equal to or greater than 65 letters. Recurrence was seen in 3 eyes (15.00%). Complications included cataract (6 patients) and ocular hypertension (4 patients).

Conclusion

A combined approach with anti-VEGF agents and anti-inflammatory therapy was effective in I-CNV treatment, and an overall good visual prognosis was attainable. Intensive follow-up was fundamental in the management of both the primary inflammatory and secondary neovascular conditions.

Nonsteroidal anti-inflammatory drugs for retinal neurodegenerative diseases

Nonsteroidal anti-inflammatory drugs (NSAIDs) are among the most common prescription drugs for inflammation, and topical NSAIDs are often used in ophthalmology to reduce pain, photophobia, inflammation, and edema. In recent years, many published reports have found that NSAIDs play an important role in the treatment of retinal neurodegenerative diseases, such as age-related macular degeneration (AMD), diabetic retinopathy (DR), glaucoma, pathological myopia, and retinitis pigmentosa (RP). The aim of the current review is to provide an overview of the role of various NSAIDs in the treatment of retinal neurodegenerative diseases and the corresponding mechanisms of action. This review highlighted that the topical application of NSAIDs for the treatment of retinal degenerative diseases has been studied to a remarkable extent and that its beneficial effects in many diseases have been proven. In the future, prospective studies with large study populations are required to extend these effects to clinical settings.

Anti-VEGF-Resistant Retinal Diseases: A Review of the Latest Treatment Options

Anti-vascular endothelial growth factor (anti-VEGF) therapy currently plays a central role in the treatment of numerous retinal diseases, most notably exudative age-related macular degeneration (eAMD), diabetic retinopathy and retinal vein occlusions. While offering significant functional and anatomic benefits in most patients, there exists a subset of 15–40% of eyes that fail to respond or only partially respond. For these cases, various treatment options have been explored with a range of outcomes. These options include steroid injections, laser treatment (both thermal therapy for retinal vascular diseases and photodynamic therapy for eAMD), abbreviated anti-VEGF treatment intervals, switching anti-VEGF agents and topical medications. In this article, we review the effectiveness of these treatment options along with a discussion of the current research into future directions for anti-VEGF-resistant eyes.

Results of Intravitreal Anti-Vascular Endothelial Growth Factor Therapy in Inflammatory Choroidal Neovascularization

Purpose:

To report the visual outcomes of intravitreal (IVT) anti-vascular endothelial growth factor (anti-VEGF) in inflammatory choroidal neovascularization (iCNV).

Methods:

A retrospective study of 43 eyes of 38 patients with active choroidal neovascularization (CNV) related to ocular inflammatory disease, treated with IVT injections of anti-VEGF (bevacizumab, ranibizumab, or aflibercept), with or without associated systemic anti-inflammatory therapy, at Fattouma Bourguiba University Hospital, Monastir, Tunisia (24 eyes of 23 patients) and at Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico, Milan, Italy (19 eyes of 15 patients) from January 1, 2013, to December 31, 2018.

Results:

The mean age was 35.5 ± 16.4 years. The sex ratio male:female was 0.27. Seventeen eyes (39.5%) of 17 patients (44.7%) had only anti-VEGF injections, and 26 eyes (60.5%) of 21 patients (45.3%) had anti-VEGF injections and associated systemic anti-inflammatory therapy. Bevacizumab was injected in 36 eyes (83.7%), ranibizumab in six eyes (14%), and aflibercept in one eye (2.3%). Mean follow-up was 20.3 ± 19.2 months (range, 6–106 months). Mean visual acuity improved from 0.8 ± 0.37 logMAR (approximate Snellen equivalent 20/125) to 0.51 ± 0.42 logMAR (approximate Snellen equivalent 20/63) (P < 0.001). Mean central macular thickness on optical coherence tomography decreased from 403.7 ± 121.9 to 293.7 ± 82.8 μm (P < 0.001). Mean gain of vision was 2.9 ± 3.1 lines. The mean number of injections was 2.5. Twenty eyes (46.5%) received a single injection. There were no side effects related to the IVT injections of anti-VEGF.

Conclusions:

CNV is a sight-threatening complication of uveitis. IVT anti-VEGF seems to be an effective and safe treatment for iCNV when inflammation is controlled.

Associations between the Complement System and Choroidal Neovascularization in Wet Age-Related Macular Degeneration

Age-related macular degeneration (AMD) is the leading cause of blindness affecting the elderly in the Western world. The most severe form of AMD, wet AMD (wAMD), is characterized by choroidal neovascularization (CNV) and acute vision loss. The current treatment for these patients comprises monthly intravitreal injections of anti-vascular endothelial growth factor (VEGF) antibodies, but this treatment is expensive, uncomfortable for the patient, and only effective in some individuals. AMD is a complex disease that has strong associations with the complement system. All three initiating complement pathways may be relevant in CNV formation, but most evidence indicates a major role for the alternative pathway (AP) and for the terminal complement complex, as well as certain complement peptides generated upon complement activation. Since the complement system is associated with AMD and CNV, a complement inhibitor may be a therapeutic option for patients with wAMD. The aim of this review is to (i) reflect on the possible complement targets in the context of wAMD pathology, (ii) investigate the results of prior clinical trials with complement inhibitors for wAMD patients, and (iii) outline important considerations when developing a future strategy for the treatment of wAMD.

Importance of continuous treatment with intravitreal aflibercept injections in patients with neovascular age-related macular degeneration-12-month post hoc analysis of the PERSEUS real-world evidence study

PURPOSE

To investigate the influence of treatment regularity with intravitreal aflibercept injections (IVT-AFL injections) on visual acuity (VA) outcomes in patients with neovascular age-related macular degeneration (nAMD) enrolled in the PERSEUS trial who received at least 7 IVT-AFL injections during the first year.

METHODS

This was a post hoc analysis of the PERSEUS trial, a prospective, non-interventional, multicenter cohort study, and included 370 patients with nAMD who had received ≥ 7 IVT-AFL injections during year 1. In addition to the prespecified subgroups of treatment-naïve and previously treated patients, results were compared between patients with regular (n = 209) and irregular (n = 161) treatment. Regular treatment was defined as initial dosing with monthly IVT-AFL injections for 3 months, then bimonthly IVT-AFL injections until month 12. Irregular treatment was defined as any deviation from regular treatment (provided ≥ 7 injections were received). The outcome of primary interest was the mean change in VA from baseline after 12 months. Further outcomes of interest included VA gain or loss, proportion of patients achieving reading vision, and percentage of patients with fluid.

RESULTS

At month 12, the mean (± standard deviation, SD) VA improvement from baseline was 6.1 ± 15.6 Early Treatment Diabetic Retinopathy Study letters in the regular cohort and 2.5 ± 16.7 letters in the irregular cohort with ≥ 7 IVT-AFL injections (P = 0.0514). Best results were obtained in the treatment-naïve regular sub-cohort with a mean ± SD VA improvement of 8.0 ± 17.7 letters, whereas treatment-naïve patients with irregular treatment experienced a considerably lower VA gain (2.8 ± 20.0 letters). Irregular treatment consistently correlated with inferior results in treatment-naïve patients. At month 12, the proportion of treatment-naïve patients who had experienced a worsening of ≥ 5 letters was 29.6% in the irregular sub-cohort versus 13.6% in the regular sub-cohort (P = 0.0049). However, among the treatment-naïve patients, the mean number of injections was significantly higher in the irregular than in the regular sub-cohort (8.0 ± 1.2 vs. 7.4 ± 0.6; P = 0.0001). Furthermore, compared with the treatment-naïve, regular sub-cohort, patients in the irregular sub-cohort had more visits (19.1 ± 8.6 vs. 16.1 ± 5.7), VA tests (14.2 ± 6.9 vs. 12.0 ± 4.6), and optical coherence tomography examinations (5.1 ± 3.7 vs. 3.4.0 ± 3.0).

CONCLUSIONS

Although irregularly treated patients received more injections and more monitoring visits during the first year of IVT-AFL treatment, they experienced worse VA outcomes than regularly treated patients.

Suppression of Ocular Vascular Inflammation through Peptide-Mediated Activation of Angiopoietin-Tie2 Signaling

Persistent inflammation is a complication associated with many ocular diseases. Changes in ocular vessels can amplify disease responses and contribute to vision loss by influencing the delivery of leukocytes to the eye, vascular leakage, and perfusion. Here, we report the anti-inflammatory activity for AXT107, a non-RGD, 20-mer αvβ3 and α5β1 integrin-binding peptide that blocks vascular endothelial growth factor (VEGF)-signaling and activates tyrosine kinase with immunoglobulin and EGF-like domains 2 (Tie2) using the normally inhibitory ligand angiopoietin 2 (Ang2). Tumor necrosis factor α (TNFα), a central inflammation mediator, induces Ang2 release from endothelial cells to enhance its stimulation of inflammation and vascular leakage. AXT107 resolves TNFα-induced vascular inflammation in endothelial cells by converting the endogenously released Ang2 into an agonist of Tie2 signaling, thereby disrupting both the synergism between TNFα and Ang2 while also preventing inhibitor of nuclear factor-κB α (IκBα) degradation directly through Tie2 signaling. This recovery of IκBα prevents nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) nuclear localization, thereby blocking NF-κB-induced inflammatory responses, including the production of VCAM-1 and ICAM-1, leukostasis, and vascular leakage in cell and mouse models. AXT107 also decreased the levels of pro-inflammatory TNF receptor 1 (TNFR1) without affecting levels of the more protective TNFR2. These data suggest that AXT107 may provide multiple benefits in the treatment of retinal/choroidal and other vascular diseases by suppressing inflammation and promoting vascular stabilization.

Combination of apolipoprotein-A-I/apolipoprotein-A-I binding protein and anti-VEGF treatment overcomes anti-VEGF resistance in choroidal neovascularization in mice

Many patients of choroidal neovascularization (CNV) are unresponsive to the current anti-VEGF treatment. The mechanisms for anti-VEGF resistance are poorly understood. We explore the unique property of the apolipoprotein A-I (apoA-I) binding protein (AIBP) that enhances cholesterol efflux from endothelial cells and macrophages to thereby limit angiogenesis and inflammation to tackle anti-VEGF resistance in CNV. We show that laser-induced CNV in mice with increased age showed increased resistance to anti-VEGF treatment, which correlates with increased lipid accumulation in macrophages. The combination of AIBP/apoA-I and anti-VEGF treatment overcomes anti-VEGF resistance and effectively suppresses CNV. Furthermore, macrophage depletion in old mice restores CNV sensitivity to anti-VEGF treatment and blunts the synergistic effect of combination therapy. These results suggest that cholesterol-laden macrophages play a critical role in inducing anti-VEGF resistance in CNV. Combination therapy by neutralizing VEGF and enhancing cholesterol removal from macrophages is a promising strategy to combat anti-VEGF resistance in CNV.

Triptolide attenuates laser-induced choroidal neovascularization via M2 macrophage in a mouse model

PURPOSE

To investigate whether triptolide has inhibitory effects on the development of choroidal neovascularization (CNV), together with its underlying anti-angiogenic mechanisms.

METHODS

CNV was induced in C57BL/6 J mice using laser photocoagulation. Triptolide at concentrations of 0.035 and 0.07 mg/kg body weight (BW) or the same volume of phosphate-buffered saline (PBS) was intraperitoneally injected into mice 2 days before laser photocoagulation, which was continued daily till the end of the experiment. CNV areas were measured on day 7. The numbers of M1, M2, and F4/80⁺ macrophages were detected on day 1, 3, and 7 in each group. The levels of vascular endothelial growth factor (VEGF) and inflammatory molecules,including intercellular adhesion molecule (ICAM)-1,tumor necrosis factor (TNF)-α, and interleukin 6 (IL-6) were determined by enzyme-linked immunosorbent assay. Cell proliferation, migration, and tube-formation assays were performed in vitro.

RESULTS

Triptolide at doses of 0.035 mg/kg BW (66,562 ± 39,253 μm², n = 5, P＜0.05) and 0.07 mg/kg BW (37,271 ± 25,182 μm², n = 5, P＜0.001) significantly reduced CNV areas by 54.9 and 74.8 %, respectively, compared with PBS control (147,699 ± 112,900 μm², n = 5) in a dose-dependent manner. Protein levels of VEGF, ICAM-1, TNF-α, and IL-6 in the RPE-choroid-sclera complex were significantly downregulated by triptolide treatment on day 3, which was in accordance with the reduced number of infiltrated F4/80⁺ macrophages and the reduced ratio of M2/F4/80⁺ macrophages. However, no toxic effects of triptolide on the retina or other systemic organs were observed. In addition, triptolide treatment exerted inhibitory effects on cell proliferation, migration, and tube formation in vitro in a concentration-dependent manner.

CONCLUSIONS

Triptolide has therapeutic potential in CNV owing to its anti-angiogenic effect.

Effects of FTMT Expression by Retinal Pigment Epithelial Cells on Features of Angiogenesis

Aberrant angiogenesis is a pathological feature of a number of diseases and arises from the uncoordinated expression of angiogenic factors as response to different cellular stresses. Age-related macular degeneration (AMD), a leading cause of vision loss, can result from pathological angiogenesis. As a mutation in the mitochondrial ferritin (FTMT) gene has been associated with AMD, its possible role in modulating angiogenic factors and angiogenesis was investigated. FTMT is an iron-sequestering protein primarily expressed in metabolically active cells and tissues with high oxygen demand, including retina. In this study, we utilized the human retinal pigment epithelial cell line ARPE-19, both as undifferentiated and differentiated cells. The effects of proinflammatory cytokines, FTMT knockdown, and transient and stable overexpression of FTMT were investigated on expression of pro-angiogenic vascular endothelial growth factor (VEGF) and anti-angiogenic pigment epithelial-derived factor (PEDF). Proinflammatory cytokines induced FTMT and VEGF expression, while NF-κB inhibition significantly reduced FTMT expression. VEGF protein and mRNA expression were significantly increased in FTMT-silenced ARPE-19 cells. Using an in vitro angiogenesis assay with endothelial cells, we showed that conditioned media from FTMT-overexpressing cells had significant antiangiogenic effects. Collectively, our findings indicate that increased levels of FTMT inhibit angiogenesis, possibly by reducing levels of VEGF and increasing PEDF expression. The cellular models developed can be used to investigate if increased FTMT may be protective in angiogenic diseases, such as AMD.

Leveraging Nuclear Receptors as Targets for Pathological Ocular Vascular Diseases

Vasculogenesis and angiogenesis are physiological mechanisms occurring throughout the body. Any disruption to the precise balance of blood vessel growth necessary to support healthy tissue, and the inhibition of abnormal vessel sprouting has the potential to negatively impact stages of development and/or healing. Therefore, the identification of key regulators of these vascular processes is critical to identifying therapeutic means by which to target vascular-associated compromises and complications. Nuclear receptors are a family of transcription factors that have been shown to be involved in modulating different aspects of vascular biology in many tissues systems. Most recently, the role of nuclear receptors in ocular biology and vasculopathies has garnered interest. Herein, we review studies that have used in vitro assays and in vivo models to investigate nuclear receptor-driven pathways in two ocular vascular diseases associated with blindness, wet or exudative age-related macular degeneration, and proliferative diabetic retinopathy. The potential therapeutic targeting of nuclear receptors for ocular diseases is also discussed.

SARI prevents ocular angiogenesis and inflammation in mice

SARI (Suppressor of AP‐1, regulated by IFN‐β) is known to play an important role in some systemic disease processes such an inflammatory conditions and cancer. We hypothesize that SARI may also play a role in ocular diseases involving inflammation and neovascularization. To explore our hypothesis, further, we investigated an endotoxin‐induced uveitis (EIU) and experimental argon laser‐induced choroidal neovascularization (CNV) model in SARI wild‐type (SARI^WT) and SARI‐deficient (SARI^−/−) mice. Through imaging, morphological and immunohistochemical (IHC) studies, we found that SARI deficiency exacerbated the growth of CNV. More VEGF‐positive cells were presented in the retina of SARI^−/− mice with CNV. Compared to SARI^WT mice, more inflammatory cells infiltrated the ocular anterior segment and posterior segments in SARI^−/− mice with EIU. Collectively, the results point to a potential dual functional role of SARI in inflammatory ocular diseases, suggesting that SARI could be a potential therapy target for ocular inflammation and neovascularization.

Pirfenidone ameliorates the formation of choroidal neovascularization in mice

The formation and development of choroidal neovascularization (CNV) is accompanied by inflammation and fibrosis. Existing treatments are expensive and can cause irreversible complications. Pirfenidone (PFD) exerts anti‑inflammatory and anti‑fibrotic effects; however, its applications in the eye remain unclear. Male C57BL/6J mice (aged 6‑8 weeks) were used to explore whether PFD can inhibit the formation of laser‑induced CNV. The localization of transforming growth factor β2 (TGFβ2) was determined through immunofluorescent staining. After laser photocoagulation, the vehicle and PFD groups were intravitreally injected with 1 µl PBS and 1 µl 0.5% PFD, respectively. At day 7 after intravitreal injection, the expression of TGFβ2 and vascular endothelial growth factor (VEGF) was assessed. Fundus fluorescein angiography was performed to investigate the extent of fluorescence leakage, and the CNV areas were analyzed using a choroidal flat mount. The results demonstrated that, on day 7 after photocoagulation, the expression of TGFβ2 and VEGF was reduced in the experimental group. In addition, fluorescein angiography showed that the leakage area of CNV was significantly smaller in the PFD injection group than those observed in the control and vehicle groups. Moreover, the areas of CNV in the PFD injection group were smaller compared with those reported in the other two injection groups. Histopathological and TUNEL analyses performed on day 28 revealed that there were no notable abnormalities on the layers of the neural retina of PFD‑treated mice. In conclusion, intravitreal injection of PFD inhibited the formation of CNV in mice, likely via the downregulation of VEGF and TGFβ2, which did not cause damage to the mouse retina after 28 days of treatment.

Central Role of Oxidative Stress in Age-Related Macular Degeneration: Evidence from a Review of the Molecular Mechanisms and Animal Models

Age-related macular degeneration (AMD) is a common cause of visual impairment in the elderly. There are very limited therapeutic options for AMD with the predominant therapies targeting vascular endothelial growth factor (VEGF) in the retina of patients afflicted with wet AMD. Hence, it is important to remind readers, especially those interested in AMD, about current studies that may help to develop novel therapies for other stages of AMD. This study, therefore, provides a comprehensive review of studies on human specimens as well as rodent models of the disease, to identify and analyze the molecular mechanisms behind AMD development and progression. The evaluation of this information highlights the central role that oxidative damage in the retina plays in contributing to major pathways, including inflammation and angiogenesis, found in the AMD phenotype. Following on the debate of oxidative stress as the earliest injury in the AMD pathogenesis, we demonstrated how the targeting of oxidative stress-associated pathways, such as autophagy and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling, might be the futuristic direction to explore in the search of an effective treatment for AMD, as the dysregulation of these mechanisms is crucial to oxidative injury in the retina. In addition, animal models of AMD have been discussed in great detail, with their strengths and pitfalls included, to assist inform in the selection of suitable models for investigating any of the molecular mechanisms.

mTORC1 and mTORC2 are differentially engaged in the development of laser-induced CNV

Background

The mechanistic target of rapamycin (mTOR) pathway is a potential target to inhibit pathologic processes in choroidal neovascularization. However, the exact role of mTOR signaling in the development of CNV remains obscure. In this study, we assessed the role of mTORC1 and mTORC2 as well as the effect of rapamycin (sirolimus) on choroidal neovascularization (CNV) in a laser-induced mouse model.

Methods

In experiment A, we observed the natural course of CNV development and the dynamics of mTOR-related proteins during the 12 days after the laser injury. The expression of mTOR-related proteins was evaluated using Western blot (WB). Cryosections of CNV-induced mice were immunostained for the visualization of the vascular and extravascular components of the CNV. Experiment B was performed to confirm the critical period of mTOR signaling in the development of laser-induced CNV, we administered rapamycin before and/or during the active period of mTOR complexes. WB and immunofluorescence staining was performed to evaluate the mode of action and the effect of mTOR inhibition on CNV development.

Results

In experiment A, we detected high levels of p-mTOR S2448 and p-mTOR S2481 from the 5th to 12th day of laser injury. Immunofluorescence imaging of cryosections of mice sacrificed on day 7 revealed greater co-immunoreactivity of p-mTOR S2448 positive cells with CD11b and F4/80, while p-mTOR S2481 positive cells showed colocalization with CD31, α-SMA, and cytokeratin. In experiment B, rapamycin injection during the active period of mTOR signaling demonstrated near-complete inhibition of CNV lesion as well as significant induction of autophagy.

Conclusion

Our study suggests the mTOR as a critical player during CNV development in laser-induced mouse model through differentially acting with the mTORC1 and mTORC2. mTORC1 activity was high predominantly in inflammatory cells in CNV lesion, while mTORC2 activity was higher in vascular components and the RPE.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0380-0) contains supplementary material, which is available to authorized users.

Impact of methylenetetrahydrofolate reductase C677T polymorphism on the efficacy of photodynamic therapy in patients with neovascular age-related macular degeneration

The most severe visual impairments due to age-related macular degeneration (AMD) are frequently caused by the occurrence of choroidal neovascularization (CNV). Although photodynamic therapy with verteporfin (PDT-V) is currently a second-line treatment for neovascular AMD, it can be conveniently combined with drugs acting against vascular endothelial growth factor (anti-VEGF) to reduce the healthcare burden associated with the growing necessity of anti-VEGF intravitreal re-injection. Because the common 677 C > T polymorphism of the methylenetetrahydrofolate reductase gene (MTHFR-C677T; rs1801133) has been described as predictor of satisfactory short-term responsiveness of AMD-related CNV to PDT-V, we retrospectively examined the outcomes of 371 Caucasian patients treated with standardized, pro-re-nata, photodynamic regimen for 24 months. Responder (R) and non-responder (NR) patients were distinguished on the basis of the total number of scheduled PDT-V (TN-PDT-V) and change of best-corrected visual acuity (∆-BCVA). The risk for both TN-PDT-V and ∆-BCVA to pass from R to NR group was strongly correlated with CT and TT genotypes of MTHFR-C677T variant resulting, respectively, in odd ratios of 0.19 [95% CI, 0.12-0.32] and 0.09 [95% CI, 0.04-0.21] (P < 0.001), and odd ratios of 0.24 [95% CI, 0.15-0.39] and 0.03 [95% CI, 0.01-0.11] (P < 0.001). These pharmacogenetic findings indicate a rational basis to optimize the future clinical application of PDT-V during the combined treatments of AMD-related CNV, highlighting the role of thrombophilia to be aware of the efficacy profile of photodynamic therapy.

Complement factor and T-cell interactions during alloimmune inflammation in transplantation

Complement factor and T-cell signaling during an effective alloimmune response plays a key role in transplant-associated injury, which leads to the progression of chronic rejection (CR). During an alloimmune response, activated complement factors (C3a and C5a) bind to their corresponding receptors (C3aR and C5aR) on a number of lymphocytes, including T-regulatory cells (Tregs), and these cell-molecular interactions have been vital to modulate an effective immune response to/from Th1-effector cell and Treg activities, which result in massive inflammation, microvascular impairments, and fibrotic remodeling. Involvement of the complement-mediated cell signaling during transplantation signifies a crucial role of complement components as a key therapeutic switch to regulate ongoing inflammatory state, and further to avoid the progression of CR of the transplanted organ. This review highlights the role of complement-T cell interactions, and how these interactions shunt the effector immune response during alloimmune inflammation in transplantation, which could be a novel therapeutic tool to protect a transplanted organ and avoid progression of CR.

[Anti-VEGF therapy resistance in neovascular age-related macular degeneration]

With account to the increase in the elderly population in most of the developed countries, the WHO defines age-related macular degeneration (AMD) as one of the main causes of blindness in the world. A large percentage of disability is accounted for by exudative, or neovascular, form of AMD. Today, a total of 5 anti-VEGF drugs exist that are recommended for treatment of exudative AMD: pegaptanib, ranibizumab, bevacizumab, aflibercept, and conbercept. Despite significant progress in the treatment of neovascular AMD yielded by the introduction into clinical practice of anti-VEGF drugs, some patients report a lack (down to complete lack) of response with standard treatment patterns and even a decrease in treatment efficacy after repeated intravitreal injections.

Theme trends and knowledge structure on choroidal neovascularization: a quantitative and co-word analysis

Background

The distribution pattern and knowledge structure of choroidal neovascularization (CNV) was surveyed based on literatures in PubMed.

Methods

Published scientific papers about CNV were retrieved from Jan 1st, 2012 to May 31st, 2017. Extracted MeSH terms were analyzed quantitatively by using Bibliographic Item Co-Occurrence Matrix Builder (BICOMB) and high-frequency MeSH terms were identified. Hierarchical cluster analysis was conducted by SPSS 19.0 according to the MeSH term-source article matrix. High-frequency MeSH terms co-occurrence matrix was constructed to support strategic diagram and social network analysis (SNA).

Results

According to the searching strategy, all together 2366 papers were included, and the number of annual papers changed slightly from Jan 1st, 2012 to May 31st, 2017. Among all the extracted MeSH terms, 44 high-frequency MeSH terms were identified and hotspots were clustered into 6 categories. In the strategic diagram, clinical drug therapy, pathology and diagnosis related researches of CNV were well developed. In contrast, the metabolism, etiology, complications, prevention and control of CNV in animal models, and genetics related researches of CNV were relatively immature, which offers potential research space for future study. As for the SNA result, the position status of each component was described by the centrality values.

Conclusions

The studies on CNV are relatively divergent and the 6 research categories concluded from this study could reflect the publication trends on CNV to some extent. By providing a quantitative bibliometric research across a 5-year span, it could help to depict an overall command of the latest topics and provide some hints for researchers when launching new projects.

Inhibition of integrin α5β1 ameliorates VEGF-induced retinal neovascularization and leakage by suppressing NLRP3 inflammasome signaling in a mouse model

PURPOSE

To assess the effect of inhibiting integrin α5β1 by ATN-161 on vascular endothelial growth factor (VEGF)-induced neovascularization (NV) and leakage causing retinal detachment in adult Tet/opsin/VEGF transgenic mice, and characterize the underlying mechanism of its function.

METHOD

Retinas from adult Tet/opsin/VEGF transgenic mice and human retinal endothelial cells (HRECs) exposed to VEGF (treated with ATN-161 or PBS) were used to carry out immunofluorescence, RT-PCR and western blot to examine expression levels of integrin α5β1 and the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome. Retinal frozen section analysis was used to assess NV and leakage causing retinal detachment.

RESULTS

In comparison to normal-treated mice, doxycycline-treated Tet/opsin/VEGF transgenic mice showed severe retinal detachment and higher integrin α5β1 expression. Furthermore, the retinal detachment was inhibited significantly by ATN-161. Additionally, ATN-161 treatment was associated with a conspicuous reduction in NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), cleaved caspase-1, and mature interleukin-1β expression levels in the retinas of Tet/opsin/VEGF transgenic mice treated with doxycycline as well as in HRECs exposed to VEGF.

CONCLUSION

ATN-161, an antagonist of integrin α5β1, is a promising treatment for retinal neovascularization (RNV), and its retinal protection role appears to take effect through inhibition of NLRP3 inflammasome activity.

A case of choroidal neovascular membrane in 6-year-old boy with juvenile idiopathic arthritis

Purpose

The purpose of this study is to report a case of choroidal neovascular membrane (CNVM) in a patient of juvenile idiopathic arthritis (JIA).

Design

The design of this study is an interventional case report.

Methods

A 6-year-old boy, a known patient of JIA, presented with a complaint of redness and ocular pain with mild diminution of vision in his left eye. Fundus examination revealed a CNVM with retinal thickening and subretinal fluid which was confirmed on OCT. Treatment with intravitreal injection of anti-VEGF (ranibizumab) and oral immunosuppressive showed resolution of the CNVM.

Results

The result of this study is a successful treatment of CNVM with a single anti-VEGF injection and systemic immunosuppression.

Conclusions

Although a rare complication, CNVM can occur in patients with JIA.

Visible-Light Optical Coherence Tomography Angiography for Monitoring Laser-Induced Choroidal Neovascularization in Mice

Purpose

This study sought to determine the earliest time-point at which evidence of choroidal neovascularization (CNV) could be detected with visible-light optical coherence tomography angiography (vis-OCTA) in a mouse model of laser-induced CNV.

Methods

Visible light-OCTA was used to study laser-induced CNV at different time-points after laser injury to monitor CNV development and measure CNV lesion size. Measurements obtained from vis-OCTA angiograms were compared with histopathologic measurements from isolectin-stained choroidal flatmounts.

Results

Choroidal neovascularization area measurements between the vis-OCTA system and isolectin-stained choroidal flatmounts were significantly different in area for days 2 to 4 postlaser injury, and were not significantly different in area for days 5, 7, and 14. Choroidal neovascularization area measurements taken from the stained flatmounts were larger than their vis-OCTA counterparts for all time-points. Both modalities showed a similar trend of CNV size increasing from the day of laser injury until a peak of day 7 postlaser injury and subsequently decreasing by day 14.

Conclusions

The earliest vis-OCTA can detect the presence of aberrant vessels in a mouse laser-induced CNV model is 5 days after laser injury. Visible light-OCTA was able to visualize the maximum of the CNV network 7 days postlaser injury, in accordance with choroidal flatmount immunostaining. Visible light-OCTA is a reliable tool in both detecting the presence of CNV development, as well as accurately determining the size of the lesion in a mouse laser-induced CNV model.

Inflammatory choroidal neovascular membrane after healed tuberculous choroidal granuloma

Objective: To present a case of choroidal granuloma masquerading as intraocular tumor that healed on anti-tuberculous treatment but led to the development of inflammatory choroidal neovascular membrane (CNVM). Method: A 42-year-old female patient with past history of hysterectomy presented with diminution of vision in the right eye. Fundus examination in the right eye showed a yellowish white choroidal mass with associated bullous retinal detachment superotemporal to fovea. Left eye fundus was normal. Fundus flourescein angiography showed early and late hyperflourescence with late pooling in serous detachments. Complete systemic evaluation did not yield a clue to diagnosis. Positron emission tomography scan (PET scan) showed enlarged lymph nodes in cervical, mediastinal and peritoneal regions. Lymph node biopsy showed caseating granulomas. Results: The granuloma subsided and a scar formed 5 months after starting anti-tuberculous treatment with improvement in vision. Six months later, the vision deteriorated again with the development of a choroidal neovascular membrane (CNVM) at the margin of the scar. The CNVM resolved and all the signs of activity subsided after giving intravitreal antivascular endothelial growth factor (anti-VEGF) injections. Conclusions: Making a diagnosis of tuberculous granuloma in a case of choroidal mass lesion is a challenge. PET scan helps in identifying metabolically active lymph nodes appropriate for biopsy. Healed scars of tuberculous choroid lesions should be followed closely to detect the development of CNVM.

SYSTEMIC BETA-BLOCKERS IN NEOVASCULAR AGE-RELATED MACULAR DEGENERATION

PURPOSE

To evaluate whether oral beta-blockers (BBs) are associated with a decreased number of intravitreal injections in patients with incident neovascular age-related macular degeneration.

METHODS

A retrospective cohort study of subjects with a new diagnosis of neovascular age-related macular degeneration was conducted using a medical claims database from a large national US insurer. Two cohorts were created for comparison consisting of patients with regular use of BBs or calcium channel blockers. The main outcome measured was the difference in the mean number of intravitreal injections administered between the two cohorts.

RESULTS

After inclusion and exclusion criteria, 239 BB and 155 calcium channel blocker subjects remained for analysis. Univariate analysis revealed that the mean number of injections in the BB cohort was 6.43 (95% confidence interval [CI] 5.90-6.95) versus 6.55 (95% CI 5.85-7.25) in the calcium channel blocker cohort (P = 0.78). After multivariate adjustment, the mean number of injections in the BB group was 6.32 (95% CI 5.77-6.87) versus 6.71 (95% CI 6.02-7.40) in the calcium channel blocker group. The overall difference between the 2 groups was -0.39 (95% CI difference -1.29 to 0.51; P = 0.40).

CONCLUSION

The use of oral BBs is not associated with a decreased number of intravitreal injections in incident neovascular age-related macular degeneration patients.

Myeloid-Specific Blockade of Notch Signaling Attenuates Choroidal Neovascularization through Compromised Macrophage Infiltration and Polarization in Mice

Macrophages have been recognized as an important inflammatory component in choroidal neovascularization (CNV). However, it is unclear how these cells are activated and polarized, how they affect angiogenesis and what the underlining mechanisms are during CNV. Notch signaling has been implicated in macrophage activation. Previously we have shown that inducible disruption of RBP-J, the critical transcription factor of Notch signaling, in adult mice results in enhanced CNV, but it is unclear what is the role of macrophage-specific Notch signaling in the development of CNV. In the current study, by using the myeloid specific RBP-J knockout mouse model combined with the laser-induced CNV model, we show that disruption of Notch signaling in macrophages displayed attenuated CNV growth, reduced macrophage infiltration and activation, and alleviated angiogenic response after laser induction. The inhibition of CNV occurred with reduced expression of VEGF and TNF-α in infiltrating inflammatory macrophages in myeloid specific RBP-J knockout mice. These changes might result in direct inhibition of EC lumen formation, as shown in an in vitro study. Therefore, clinical intervention of Notch signaling in CNV needs to pinpoint myeloid lineage to avoid the counteractive effects of global inhibition.

Resistance to anti-VEGF therapy in neovascular age-related macular degeneration: a comprehensive review

As a progressive chronic disease, age-related macular degeneration (AMD) is the leading cause of irreversible vision impairment worldwide. Experimental and clinical evidence has demonstrated that vascular endothelial growth factor (VEGF) plays a vital role in the formation of choroidal neovascularization. Intravitreal injections of anti-VEGF agents have been recommended as a first-line treatment for neovascular AMD. However, persistent fluid or recurrent exudation still occurs despite standardized anti-VEGF therapy. Patients suffering from refractory or recurrent neovascular AMD may develop mechanisms of resistance to anti-VEGF therapy, which results in a diminished therapeutic effect. Until now, there has been no consensus on the definitions of refractory neovascular AMD and recurrent neovascular AMD. This article aims at clarifying these concepts to evaluate the efficacy of switching drugs, which contributes to making clinical decision more scientifically. Furthermore, insight into the causes of resistance to anti-VEGF therapy would be helpful for developing possible therapeutic approaches, such as combination therapy and multi-target treatment that can overcome this resistance.

EFFECT OF SYSTEMIC BETA-BLOCKERS, ACE INHIBITORS, AND ANGIOTENSIN RECEPTOR BLOCKERS ON DEVELOPMENT OF CHOROIDAL NEOVASCULARIZATION IN PATIENTS WITH AGE-RELATED MACULAR DEGENERATION

PURPOSE

Recent studies have suggested that the use of systemic beta-blockers, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers can induce regression of choroidal neovascularization in rodent models. The purpose of this study is to evaluate if these agents have a protective effect against the development of choroidal neovascularization in patients with age-related macular degeneration.

METHODS

In this single-center retrospective case-control study, the charts of 250 patients with neovascular age-related macular degeneration were compared with those of 250 controls with dry age-related macular degeneration. Charts were reviewed for current and past use of beta-blockers, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers. Frequency tables were generated, and associations were examined using chi-square tests, t-tests, and multivariate logistic regression.

RESULTS

There was no statistically significant difference between rates of beta-blocker use (P = 0.57), angiotensin-converting enzyme inhibitors use (P = 0.20), or angiotensin receptor blockers use (P = 0.61) between the 2 groups. Additionally, there was no statistically significant difference between rates of use of combinations of the above drugs between the two groups.

CONCLUSION

Although there is growing evidence that beta-blockers, angiotensin-converting enzyme inhibitors, and angiotensin receptor blockers can induce regression of choroidal neovascularization in rodent models, these medications do not seem to confer a protective effect against the development of choroidal neovascularization in patients with age-related macular degeneration.

Inhibition of RACK1 ameliorates choroidal neovascularization formation in vitro and in vivo

Choroidal neovascularization (CNV) occurs as a result of age-related macular degeneration (AMD) and causes severe vision loss among elderly patients. The receptor for activated C-kinase 1 (RACK1) serves as a scaffold protein which is recently found to promote angiogenesis. However, the impact of RACK1 on the vascular endothelial growth factor (VEGF) expression in endothelial cells and subsequent choroidal angiogenesis formation remains to be elucidated. In this study, we found that RACK1 and VEGF expression increased, and reached the peak at 7d in mouse CNV model by laser application. Furthermore, on RPE/choroid cryosections, RACK1 co-localized with CD31, suggesting that RACK1 was expressed in endothelial cells. In vitro, RF/6A cell hypoxia model showed that RACK1 expression was up-regulated in parallel with hypoxia-induced factor 1 (HIF-1α) and VEGF expression, reaching the peak at 6h. Silencing of RACK1 suppressed the invasion and tube formation activity of RF/6A cells in ARPE-19 and RF/6A co-culture system, possibly through VEGF signal pathway. Overexpression of RACK1 showed the opposite effect. Intravitreal injection of anti-RACK1 monoclonal antibody predominantly decreased RACK1 and VEGF expression in mouse laser-induced CNV model. Meanwhile, anti-RACK1 monoclonal antibody intravitreal injection also decreased incidence of CNV and leakage area. These data indicated that RACK1 promoted CNV formation via VEGF pathway. Additionally, anti-RACK1 monoclonal antibody significantly decreased CNV in mouse model and may have therapeutic potential in human CNV.

Aflibercept efficacy in refractory choroidal neovascularization

The aim of the report is to evaluate the short-term efficacy and safety of aflibercept (EYLEA®) in patients with choroidal neovascularization (CNV) transformed into refractory during treatment with bevacizumab (AVASTIN ®).

METHODS

Clinical, morphological, and functional changes were retrospectively evaluated in cases with refractory CNVs to monthly 1.25 mg bevacizumab intravitreal injections (AVASTIN ®) and switched to 3 monthly 2.0 mg intravitreal injections of aflibercept (EYLEA ®).

RESULTS

In this pilot evaluation, 8 cases of CNVs that become refractory to intravitreal treatment with 1.25 mg intravitreal bevacizumab (AVASTIN ®), were switched to 2.0 mg intravitreal aflibercept (EYLEA ®) and evaluated. The mean age of patients was 67.6 years (54-74 years). In 7 cases, CNV was associated to age related macular degeneration and in 1 case to angioid streaks. The mean number of previous intravitreal bevacizumab (AVASTIN®) administrations was 9.32 (7-12). In all cases, the last 3 intravitreal injections of bevacizumab were performed at an interval of maximum 6 weeks. The refractory status was confirmed by the lack of improvement or worsening of the clinical features as revealed by SD-OCT. A slowly anatomical improvement was noticed in 5 out of 8 cases (62.5%) since the first aflibercept administration. The anatomical improvement was stable after 3 monthly administrations. During the treatment, only 3 out of 5 cases (60%) showing anatomical improvement had a minor visual benefit (one line of VA gain). In 3 cases, the treatment change was unremarkable. No side effects were noticed.

CONCLUSIONS

The anatomical improvement confirms previous reports regarding the efficacy and safety of aflibercept (EYLEA®) in some cases of CNV that became refractory during conventional anti-VEGF therapy. The improvement can be, at least partially, explained by the more complex features of aflibercept. Unfortunately, a minor visual benefit was noticed in a limited number of cases.

Angiopoietin-like Protein 2 Is a Multistep Regulator of Inflammatory Neovascularization in a Murine Model of Age-related Macular Degeneration

Choroidal neovascularization (CNV) is a pathogenic process of age-related macular degeneration, a vision-threatening disease. The retinal pigment epithelium and macrophages both influence CNV development. However, the underlying mechanisms remain obscure. Here, we focus on Angptl2 (angiopoietin-like protein 2), a cytokine involved in age-related systemic diseases. Angptl2 was originally identified as an adipocytokine and is also expressed in the eye. Using a laser-induced CNV model, we found thatAngptl2KO mice exhibited suppressed CNV development with reduced macrophage recruitment and inflammatory mediator induction. The mediators monocyte chemotactic protein-1, interleukin-1β (Il-1β),Il-6, matrix metalloprotease-9 (Mmp-9), and transforming growth factor-β1 (Tgf-β1) that were up-regulated during CNV development were all suppressed in the retinal pigment epithelium-choroid of CNV models generated in theAngptl2KO mice. Bone marrow transplantation using wild-type and KO mice suggested that both bone marrow-derived and host-derived Angptl2 were responsible for macrophage recruitment and CNV development. Peritoneal macrophages derived fromAngptl2KO mice expressed lower levels of the inflammatory mediators. In the wild-type peritoneal macrophages and RAW264.7 cells, Angptl2 induced the mediators via integrins α4 and β2, followed by the downstream activation of NF-κB and ERK. The activation of NF-κB and ERK by Angptl2 also promoted macrophage migration. Therefore, Angptl2 from focal tissue might trigger macrophage recruitment, and that from recruited macrophages might promote expression of inflammatory mediators including Angptl2 in an autocrine and/or paracrine fashion to facilitate CNV development. Angptl2 might therefore represent a multistep regulator of CNV pathogenesis and serve as a new therapeutic target for age-related macular degeneration.

Antiangiogenic and Neurogenic Activities of Sleeping Beauty-Mediated PEDF-Transfected RPE Cells In Vitro and In Vivo

Pigment epithelium-derived factor (PEDF) is a potent multifunctional protein that inhibits angiogenesis and has neurogenic and neuroprotective properties. Since the wet form of age-related macular degeneration is characterized by choroidal neovascularization (CNV), PEDF would be an ideal candidate to inhibit CNV and support retinal pigment epithelial (RPE) cells. However, its short half-life has precluded its clinical use. To deliver PEDF to the subretinal space, we transfected RPE cells with the PEDF gene using the Sleeping Beauty transposon system. Transfected cells expressed and secreted biologically active recombinant PEDF (rPEDF). In cultures of human umbilical vein endothelial cells, rPEDF reduced VEGF-induced cumulative sprouting by ≥47%, decreased migration by 77%, and increased rate of apoptosis at least 3.4 times. rPEDF induced neurite outgrowth in neuroblastoma cells and protected ganglion and photoreceptor cells in organotypic retinal cultures. In a rat model of CNV, subretinal transplantation of PEDF-transfected cells led to a reduction of the CNV area by 48% 14 days after transplantation and decreased clinical significant lesions by 55% and 40% after 7 and 14 days, respectively. We showed that transplantation of pigment epithelial cells overexpressing PEDF can restore a permissive subretinal environment for RPE and photoreceptor maintenance, while inhibiting choroidal blood vessel growth.