ADAM9 Is Involved in Pathological Retinal Neovascularization

ABSTRACT Pathological ocular neovascularization, caused by diabetic retinopathy, age-related macular degeneration, or retinopathy of prematurity, is a leading cause of blindness, yet much remains to be learned about its underlying causes. Here we used oxygen-induced retinopathy (OIR) and laser-induced choroidal neovascularization (CNV) to assess the contribution of the metalloprotease-disintegrin ADAM9 to ocular neovascularization in mice. Pathological neovascularization in both the OIR and CNV models was significantly reduced in Adam9 − / − mice compared to wild-type controls. In addition, the level of ADAM9 expression was strongly increased in endothelial cells in pathological vascular tufts in the OIR model. Moreover, tumor growth from heterotopically injected B16F0 melanoma cells was reduced in Adam9 − / − mice compared to controls. In cell-based assays, the overexpression of ADAM9 enhanced the ectodomain shedding of EphB4, Tie-2, Flk-1, CD40, VCAM, and VE-cadherin, so the enhanced expression of ADAM9 could potentially affect pathological neovascularization by increasing the shedding of these and other membrane proteins from endothelial cells. Finally, we provide the first evidence for the upregulation of ADAM9-dependent shedding by reactive oxygen species, which in turn are known to play a critical role in OIR. Collectively, these results suggest that ADAM9 could be an attractive target for the prevention of proliferative retinopathies, CNV, and cancer.

Download Full-text

SCF (Stem Cell Factor) and cKIT Modulate Pathological Ocular Neovascularization

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvbaha.119.313179 ◽

2019 ◽

Vol 39 (10) ◽

pp. 2120-2131 ◽

Cited By ~ 4

Author(s):

Koung Li Kim ◽

Songyi Seo ◽

Jee Taek Kim ◽

Jaetaek Kim ◽

Won Kim ◽

...

Keyword(s):

Endothelial Cells ◽

Stem Cell ◽

Stem Cell Factor ◽

Nuclear Translocation ◽

Glycogen Synthase ◽

Mutant Mice ◽

Age Related Macular Degeneration ◽

Ocular Neovascularization ◽

Oxygen Induced Retinopathy ◽

Age Related

Objective: Aberrant neovascularization is a leading cause of blindness in several eye diseases, including age-related macular degeneration and proliferative diabetic retinopathy. The identification of key regulators of pathological ocular neovascularization has been a subject of extensive research and great therapeutic interest. Here, we explored the previously unrecognized role of cKIT and its ligand, SCF (stem cell factor), in the pathological ocular neovascularization process. Approach and Results: Compared with normoxia, hypoxia, a crucial driver of neovascularization, caused cKIT to be highly upregulated in endothelial cells, which significantly enhanced the angiogenic response of endothelial cells to SCF. In murine models of pathological ocular neovascularization, such as oxygen-induced retinopathy and laser-induced choroidal neovascularization models, cKIT and SCF expression was significantly increased in ocular tissues, and blockade of cKIT and SCF using cKit mutant mice and anti-SCF neutralizing IgG substantially suppressed pathological ocular neovascularization. Mechanistically, SCF/cKIT signaling induced neovascularization through phosphorylation of glycogen synthase kinase-3β and enhancement of the nuclear translocation of β-catenin and the transcription of β-catenin target genes related to angiogenesis. Inhibition of β-catenin-mediated transcription using chemical inhibitors blocked SCF-induced in vitro angiogenesis in hypoxia, and injection of a β-catenin agonist into cKit mutant mice with oxygen-induced retinopathy significantly enhanced pathological neovascularization in the retina. Conclusions; Our data reveal that SCF and cKIT are promising novel therapeutic targets for treating vision-threatening ocular neovascular diseases.

Download Full-text

Ref-1/APE1 inhibition with novel small molecules blocks ocular neovascularization

10.1101/296590 ◽

2018 ◽

Author(s):

Sardar Pasha Sheik Pran Babu ◽

Kamakshi Sishtla ◽

Rania S. Sulaiman ◽

Bomina Park ◽

Trupti Shetty ◽

...

Keyword(s):

Endothelial Cells ◽

Ex Vivo ◽

Age Related Macular Degeneration ◽

Lesion Volume ◽

Ocular Neovascularization ◽

Age Related ◽

Promising Therapeutic Approach ◽

Dna Binding Assay

AbstractOcular neovascular diseases like wet age-related macular degeneration are a major cause of blindness. Novel therapies are greatly needed for these diseases. One appealing antiangiogenic target is reduction-oxidation factor 1-apurinic/apyrimidinic endonuclease 1 (Ref-1/APE1). This protein can act as a redox-sensitive transcriptional activator for NF-κB and other pro-angiogenic transcription factors. An existing inhibitor of Ref-1’s function, APX3330, previously showed antiangiogenic effects. Here, we developed improved APX3330 derivatives and assessed their antiangiogenic activity. We synthesized APX2009 and APX2014 and demonstrated enhanced inhibition of Ref-1 function in a DNA-binding assay compared to APX3330. Both compounds were antiproliferative against human retinal microvascular endothelial cells (HRECs; GI50 APX2009: 1.1 μM, APX2014: 110 nM) and macaque choroidal endothelial cells (Rf/6a GI50APX2009: 26 μM, APX2014: 5.0 μM). Both compounds significantly reduced the ability of HRECs and Rf/6a cells to form tubes at mid nanomolar concentrations compared to control, and both significantly inhibited HREC and Rf/6a cell migration in a scratch wound assay, reducing NF-κB activation and downstream targets.Ex vivo, both APX2009 and APX2014 inhibited choroidal sprouting at low micromolar and high nanomolar concentrations respectively. In the laser-induced choroidal neovascularization mouse model, intraperitoneal APX2009 treatment significantly decreased lesion volume by 4-fold compared to vehicle (p< 0.0001, ANOVA with Dunnett’s post hoc tests), without obvious intraocular or systemic toxicity. Thus, Ref-1 inhibition with APX2009 and APX2014 blocks ocular angiogenesisin vitroandex vivo, and APX2009 is an effective systemic therapy for CNVin vivo, establishing Ref-1 inhibition as a promising therapeutic approach for ocular neovascularization.

Download Full-text

The Different Facades of Retinal and Choroidal Endothelial Cells in Response to Hypoxia

International Journal of Molecular Sciences ◽

10.3390/ijms19123846 ◽

2018 ◽

Vol 19 (12) ◽

pp. 3846 ◽

Cited By ~ 12

Author(s):

Effat Alizadeh ◽

Parviz Mammadzada ◽

Helder André

Keyword(s):

Endothelial Cells ◽

Oxygen Deficiency ◽

Age Related Macular Degeneration ◽

Vascular Endothelial ◽

Hypoxia Inducible Factors ◽

Ocular Neovascularization ◽

Age Related ◽

Vascular Beds ◽

Angiogenic Genes ◽

Endothelial Growth Factors

Ocular angiogenic diseases, such as proliferative diabetic retinopathy and neovascular age-related macular degeneration, are associated with severe loss of vision. These pathologies originate from different vascular beds, retinal and choroidal microvasculatures, respectively. The activation of endothelial cells (EC) plays pivotal roles in angiogenesis, often triggered by oxygen deficiency. Hypoxia-inducible factors in ECs mediate the transcription of multiple angiogenic genes, including the canonical vascular endothelial growth factors. ECs show notable heterogeneity in function, structure, and disease, therefore the understanding of retinal/choroidal ECs (REC; CEC) biochemical and molecular responses to hypoxia may offer key insights into tissue-specific vascular targeting treatments. The aim of this review is to discuss the differences spanning between REC and CEC, with focus on their response to hypoxia, which could provide innovative and sustainable strategies for site specific targeting of ocular neovascularization.

Download Full-text

Stabilization of myeloid-derived HIFs promotes vascular regeneration in retinal ischemia

Angiogenesis ◽

10.1007/s10456-019-09681-1 ◽

2019 ◽

Vol 23 (2) ◽

pp. 83-90

Author(s):

Pilar Villacampa ◽

Sidath E. Liyanage ◽

Izabela P. Klaska ◽

Enrico Cristante ◽

Katja E. Menger ◽

...

Keyword(s):

Incident Light ◽

Retinal Ischemia ◽

Age Related Macular Degeneration ◽

Metabolic Demand ◽

Ocular Neovascularization ◽

Oxygen Induced Retinopathy ◽

Vascular Regeneration ◽

Age Related ◽

Vascular Insufficiency ◽

High Metabolic Demand

Abstract The retinal vasculature is tightly organized in a structure that provides for the high metabolic demand of neurons while minimizing interference with incident light. The adverse impact of retinal vascular insufficiency is mitigated by adaptive vascular regeneration but exacerbated by pathological neovascularization. Aberrant growth of neovessels in the retina is responsible for impairment of sight in common blinding disorders including retinopathy of prematurity, proliferative diabetic retinopathy, and age-related macular degeneration. Myeloid cells are key players in this process, with diverse roles that can either promote or protect against ocular neovascularization. We have previously demonstrated that myeloid-derived VEGF, HIF1, and HIF2 are not essential for pathological retinal neovascularization. Here, however, we show by cell-specific depletion of Vhl in a mouse model of retinal ischemia (oxygen-induced retinopathy, OIR) that myeloid-derived HIFs promote VEGF and bFGF expression and enhance vascular regeneration in association with improved density and organization of the astrocytic network.

Download Full-text

Molecular Mechanisms of Complement System Proteins and Matrix Metalloproteinases in the Pathogenesis of Age-Related Macular Degeneration

Current Molecular Medicine ◽

10.2174/1566524019666190828150625 ◽

2019 ◽

Vol 19 (10) ◽

pp. 705-718 ◽

Cited By ~ 4

Author(s):

Naima Mansoor ◽

Fazli Wahid ◽

Maleeha Azam ◽

Khadim Shah ◽

Anneke I. den Hollander ◽

...

Keyword(s):

Matrix Metalloproteinases ◽

Macular Degeneration ◽

Complement System ◽

Molecular Mechanisms ◽

Critical Role ◽

Age Related Macular Degeneration ◽

Genetic Changes ◽

Complement System Proteins ◽

Age Related ◽

Common Genetic Variants

: Age-related macular degeneration (AMD) is an eye disorder affecting predominantly the older people above the age of 50 years in which the macular region of the retina deteriorates, resulting in the loss of central vision. The key factors associated with the pathogenesis of AMD are age, smoking, dietary, and genetic risk factors. There are few associated and plausible genes involved in AMD pathogenesis. Common genetic variants (with a minor allele frequency of >5% in the population) near the complement genes explain 40–60% of the heritability of AMD. The complement system is a group of proteins that work together to destroy foreign invaders, trigger inflammation, and remove debris from cells and tissues. Genetic changes in and around several complement system genes, including the CFH, contribute to the formation of drusen and progression of AMD. Similarly, Matrix metalloproteinases (MMPs) that are normally involved in tissue remodeling also play a critical role in the pathogenesis of AMD. MMPs are involved in the degradation of cell debris and lipid deposits beneath retina but with age their functions get affected and result in the drusen formation, succeeding to macular degeneration. In this review, AMD pathology, existing knowledge about the normal and pathological role of complement system proteins and MMPs in the eye is reviewed. The scattered data of complement system proteins, MMPs, drusenogenesis, and lipofusogenesis have been gathered and discussed in detail. This might add new dimensions to the understanding of molecular mechanisms of AMD pathophysiology and might help in finding new therapeutic options for AMD.

Download Full-text

Updates in deep learning research in ophthalmology

Clinical Science ◽

10.1042/cs20210207 ◽

2021 ◽

Vol 135 (20) ◽

pp. 2357-2376

Author(s):

Wei Yan Ng ◽

Shihao Zhang ◽

Zhaoran Wang ◽

Charles Jit Teng Ong ◽

Dinesh V. Gunasekeran ◽

...

Keyword(s):

Deep Learning ◽

Critical Role ◽

Disease Classification ◽

Age Related Macular Degeneration ◽

Security And Privacy ◽

Generative Adversarial Networks ◽

End User ◽

Ethical Assessment ◽

Age Related ◽

Patient Consent

Abstract Ophthalmology has been one of the early adopters of artificial intelligence (AI) within the medical field. Deep learning (DL), in particular, has garnered significant attention due to the availability of large amounts of data and digitized ocular images. Currently, AI in Ophthalmology is mainly focused on improving disease classification and supporting decision-making when treating ophthalmic diseases such as diabetic retinopathy, age-related macular degeneration (AMD), glaucoma and retinopathy of prematurity (ROP). However, most of the DL systems (DLSs) developed thus far remain in the research stage and only a handful are able to achieve clinical translation. This phenomenon is due to a combination of factors including concerns over security and privacy, poor generalizability, trust and explainability issues, unfavorable end-user perceptions and uncertain economic value. Overcoming this challenge would require a combination approach. Firstly, emerging techniques such as federated learning (FL), generative adversarial networks (GANs), autonomous AI and blockchain will be playing an increasingly critical role to enhance privacy, collaboration and DLS performance. Next, compliance to reporting and regulatory guidelines, such as CONSORT-AI and STARD-AI, will be required to in order to improve transparency, minimize abuse and ensure reproducibility. Thirdly, frameworks will be required to obtain patient consent, perform ethical assessment and evaluate end-user perception. Lastly, proper health economic assessment (HEA) must be performed to provide financial visibility during the early phases of DLS development. This is necessary to manage resources prudently and guide the development of DLS.

Download Full-text

Generating iPSC-Derived Choroidal Endothelial Cells to Study Age-Related Macular Degeneration

Investigative Opthalmology & Visual Science ◽

10.1167/iovs.15-17073 ◽

2015 ◽

Vol 56 (13) ◽

pp. 8258 ◽

Cited By ~ 24

Author(s):

Allison E. Songstad ◽

Luke A. Wiley ◽

Khahn Duong ◽

Emily Kaalberg ◽

Miles J. Flamme-Wiese ◽

...

Keyword(s):

Endothelial Cells ◽

Macular Degeneration ◽

Age Related Macular Degeneration ◽

Age Related

Download Full-text

Role of Activating Transcription Factor 4 in Murine Choroidal Neovascularization Model

International Journal of Molecular Sciences ◽

10.3390/ijms22168890 ◽

2021 ◽

Vol 22 (16) ◽

pp. 8890

Author(s):

Hiroto Yasuda ◽

Miruto Tanaka ◽

Anri Nishinaka ◽

Shinsuke Nakamura ◽

Masamitsu Shimazawa ◽

...

Keyword(s):

Endothelial Cells ◽

Transcription Factor ◽

Er Stress ◽

Choroidal Neovascularization ◽

Retinal Pigment ◽

Age Related Macular Degeneration ◽

Activating Transcription Factor 4 ◽

Age Related ◽

Activating Transcription Factor ◽

Transcription Factor 4

Neovascular age-related macular degeneration (nAMD) featuring choroidal neovascularization (CNV) is the principal cause of irreversible blindness in elderly people in the world. Integrated stress response (ISR) is one of the intracellular signals to be adapted to various stress conditions including endoplasmic reticulum (ER) stress. ISR signaling results in the upregulation of activating transcription factor 4 (ATF4), which is a mediator of ISR. Although recent studies have suggested ISR contributes to the progression of some age-related disorders, the effects of ATF4 on the development of CNV remain unclear. Here, we performed a murine model of laser-induced CNV and found that ATF4 was highly expressed in endothelial cells of the blood vessels of the CNV lesion site. Exposure to integrated stress inhibitor (ISRIB) reduced CNV formation, vascular leakage, and the upregulation of vascular endothelial growth factor (VEGF) in retinal pigment epithelium (RPE)-choroid-sclera complex. In human retinal microvascular endothelial cells (HRMECs), ISRIB reduced the level of ATF4 and VEGF induced by an ER stress inducer, thapsigargin, and recombinant human VEGF. Moreover, ISRIB decreased the VEGF-induced cell proliferation and migration of HRMECs. Collectively, our findings showed that pro-angiogenic effects of ATF4 in endothelial cells may be a potentially therapeutic target for patients with nAMD.

Download Full-text

Variability of the Transferrin Receptor 2 Gene in AMD

Disease Markers ◽

10.1155/2014/507356 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Daniel Wysokinski ◽

Janusz Blasiak ◽

Mariola Dorecka ◽

Marta Kowalska ◽

Jacek Robaszkiewicz ◽

...

Keyword(s):

Oxidative Stress ◽

Risk Factors ◽

Transferrin Receptor ◽

Fenton Reaction ◽

Iron Homeostasis ◽

Critical Role ◽

Age Related Macular Degeneration ◽

Age Related ◽

Its Gene ◽

Transferrin Receptor 2

Oxidative stress is a major factor in the pathogenesis of age-related macular degeneration (AMD). Iron may catalyze the Fenton reaction resulting in overproduction of reactive oxygen species. Transferrin receptor 2 plays a critical role in iron homeostasis and variability in its gene may influence oxidative stress and AMD occurrence. To verify this hypothesis we assessed the association between polymorphisms of theTFR2gene and AMD. A total of 493 AMD patients and 171 matched controls were genotyped for the two polymorphisms of theTFR2gene: c.1892C>T (rs2075674) and c.−258+123T>C (rs4434553). We also assessed the modulation of some AMD risk factors by these polymorphisms. The CC and TT genotypes of the c.1892C>T were associated with AMD occurrence but the latter only in obese patients. The other polymorphism was not associated with AMD occurrence, but the CC genotype was correlated with an increasing AMD frequency in subjects withBMI<26. The TT genotype and the T allele of this polymorphism decreased AMD occurrence in subjects above 72 years, whereas the TC genotype and the C allele increased occurrence of AMD in this group. The c.1892C>T and c.−258+123T>C polymorphisms of theTRF2gene may be associated with AMD occurrence, either directly or by modulation of risk factors.

Download Full-text