Browsing by Author "Hartman, Gabriella D."

Now showing 1 - 8 of 8
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    An improved method for murine laser-induced choroidal neovascularization lesion quantification from optical coherence tomography images
    (Elsevier, 2022-08-02) Jensen, Nathan R.; Lambert-Cheatham, Nathan; Hartman, Gabriella D.; Muniyandi, Anbukkarasi; Park, Bomina; Sishtla, Kamakshi; Corson, Timothy W.; Ophthalmology, School of Medicine
    Laser-induced choroidal neovascularization (L-CNV) in murine models is a standard method for assessing therapies, genetics, and mechanisms relevant to the blinding eye disease neovascular or "wet" age-related macular degeneration. The ex vivo evaluation of these lesions involves confocal microscopy analysis. In vivo evaluation via optical coherence tomography (OCT) has previously been established and allows longitudinal assessment of lesion development. However, to produce robust data, evaluation of many lesions may be required, which can be a slow, arduous process. A prior, manual method for quantifying these lesions as ellipsoids from orthogonal OCT images was effective but time consuming. We therefore developed an OCT lesion quantification that is simplified, streamlined, and less time-consuming.
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    Beyond VEGF: Targeting Inflammation and Other Pathways for Treatment of Retinal Disease
    (American Society for Pharmacology and Experimental Therapeutics, 2023) Muniyandi, Anbukkarasi; Hartman, Gabriella D.; Song, Yang; Mijit, Mahmut; Kelley, Mark R.; Corson, Timothy W.; Ophthalmology, School of Medicine
    Neovascular eye diseases include conditions such as retinopathy of prematurity, proliferative diabetic retinopathy, and neovascular age-related macular degeneration. Together, they are a major cause of vision loss and blindness worldwide. The current therapeutic mainstay for these diseases is intravitreal injections of biologics targeting vascular endothelial growth factor (VEGF) signaling. Lack of universal response to these anti-VEGF agents coupled with the challenging delivery method underscore a need for new therapeutic targets and agents. In particular, proteins that mediate both inflammatory and proangiogenic signaling are appealing targets for new therapeutic development. Here, we review agents currently in clinical trials and highlight some promising targets in preclinical and early clinical development, focusing on the redox-regulatory transcriptional activator APE1/Ref-1, the bioactive lipid modulator soluble epoxide hydrolase, the transcription factor RUNX1, and others. Small molecules targeting each of these proteins show promise for blocking neovascularization and inflammation. The affected signaling pathways illustrate the potential of new antiangiogenic strategies for posterior ocular disease. SIGNIFICANCE STATEMENT: Discovery and therapeutic targeting of new angiogenesis mediators is necessary to improve treatment of blinding eye diseases like retinopathy of prematurity, diabetic retinopathy, and neovascular age-related macular degeneration. Novel targets undergoing evaluation and drug discovery work include proteins important for both angiogenesis and inflammation signaling, including APE1/Ref-1, soluble epoxide hydrolase, RUNX1, and others.
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    Decreased Expression of Soluble Epoxide Hydrolase Suppresses Murine Choroidal Neovascularization
    (MDPI, 2022-12) Park, Bomina; Sardar Pasha, Sheik Pran Babu; Sishtla, Kamakshi L.; Hartman, Gabriella D.; Qi, Xiaoping; Boulton, Michael E.; Corson, Timothy W.; Ophthalmology, School of Medicine
    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.
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    Identification of Novel Pathways Regulated by APE1/Ref-1 in Human Retinal Endothelial Cells
    (MDPI, 2023-01) Mijit, Mahmut; Liu, Sheng; Sishtla, Kamakshi; Hartman, Gabriella D.; Wan, Jun; Corson, Timothy W.; Kelley, Mark R.; Ophthalmology, School of Medicine
    APE1/Ref-1 (apurinic/apyrimidinic endonuclease 1, APE1 or APEX1; redox factor-1, Ref-1) is a dual-functional enzyme with crucial roles in DNA repair, reduction/oxidation (redox) signaling, and RNA processing and metabolism. The redox function of Ref-1 regulates several transcription factors, such as NF-κB, STAT3, HIF-1α, and others, which have been implicated in multiple human diseases, including ocular angiogenesis, inflammation, and multiple cancers. To better understand how APE1 influences these disease processes, we investigated the effects of APEX1 knockdown (KD) on gene expression in human retinal endothelial cells. This abolishes both DNA repair and redox signaling functions, as well as RNA interactions. Using RNA-seq analysis, we identified the crucial signaling pathways affected following APEX1 KD, with subsequent validation by qRT-PCR. Gene expression data revealed that multiple genes involved in DNA base excision repair, other DNA repair pathways, purine or pyrimidine metabolism signaling, and histidine/one carbon metabolism pathways were downregulated by APEX1 KD. This is in contrast with the alteration of pathways by APEX1 KD in human cancer lines, such as pancreatic ductal adenocarcinoma, lung, HeLa, and malignant peripheral nerve sheath tumors. These results highlight the unique role of APE1/Ref-1 and the clinical therapeutic potential of targeting APE1 and pathways regulated by APE1 in the eye. These findings provide novel avenues for ocular neovascularization treatment.
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    Inhibition of APE1/Ref-1 for Neovascular Eye Diseases: From Biology to Therapy
    (MDPI, 2021-09) Hartman, Gabriella D.; Lambert-Cheatham, Nathan A.; Kelley, Mark R.; Corson, Timothy W.; Ophthalmology, School of Medicine
    Proliferative diabetic retinopathy (PDR), neovascular age-related macular degeneration (nvAMD), retinopathy of prematurity (ROP) and other eye diseases are characterized by retinal and/or choroidal neovascularization, ultimately causing vision loss in millions of people worldwide. nvAMD and PDR are associated with aging and the number of those affected is expected to increase as the global median age and life expectancy continue to rise. With this increase in prevalence, the development of novel, orally bioavailable therapies for neovascular eye diseases that target multiple pathways is critical, since current anti-vascular endothelial growth factor (VEGF) treatments, delivered by intravitreal injection, are accompanied with tachyphylaxis, a high treatment burden and risk of complications. One potential target is apurinic/apyrimidinic endonuclease 1/reduction-oxidation factor 1 (APE1/Ref-1). The multifunctional protein APE1/Ref-1 may be targeted via inhibitors of its redox-regulating transcription factor activation activity to modulate angiogenesis, inflammation, oxidative stress response and cell cycle in neovascular eye disease; these inhibitors also have neuroprotective effects in other tissues. An APE1/Ref-1 small molecule inhibitor is already in clinical trials for cancer, PDR and diabetic macular edema. Efforts to develop further inhibitors are underway. APE1/Ref-1 is a novel candidate for therapeutically targeting neovascular eye diseases and alleviating the burden associated with anti-VEGF intravitreal injections.
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    Ref-1 is overexpressed in neovascular eye disease and targetable with a novel inhibitor
    (Springer, 2025-01-05) Muniyandi, Anbukkarasi; Hartman, Gabriella D.; Sishtla, Kamakshi; Rai, Ratan; Gomes, Cátia; Day, Kristina; Song, Yang; Masters, Andi R.; Quinney, Sara K.; Qi, Xiaoping; Woods, Hailey; Boulton, Michael E.; Meyer, Jason S.; Vilseck, Jonah Z.; Georgiadis, Millie M.; Kelley, Mark R.; Corson, Timothy W.; Pharmacology and Toxicology, School of Medicine
    Reduction-oxidation factor-1 or apurinic/apyrimidinic endonuclease 1 (Ref-1/APE1) is a crucial redox-sensitive activator of transcription factors such as NF-κB, HIF-1α, STAT-3 and others. It could contribute to key features of ocular neovascularization including inflammation and angiogenesis; these underlie diseases like neovascular age-related macular degeneration (nAMD). We previously revealed a role for Ref-1 in the growth of ocular endothelial cells and in choroidal neovascularization (CNV). Here, we set out to further explore Ref-1 in neovascular eye disease. Ref-1 was highly expressed in human nAMD, murine laser-induced CNV and Vldlr-/- mouse subretinal neovascularization (SRN). Ref-1's interaction with a redox-specific small molecule inhibitor, APX2009, was shown by NMR and docking. This compound blocks crucial angiogenic features in multiple endothelial cell types. APX2009 also ameliorated murine laser-induced choroidal neovascularization (L-CNV) when delivered intravitreally. Moreover, systemic APX2009 reduced murine SRN and downregulated the expression of Ref-1 redox regulated HIF-1α target carbonic anhydrase 9 (CA9) in the Vldlr-/- mouse model. Our data validate the redox function of Ref-1 as a critical regulator of ocular angiogenesis, indicating that inhibition of Ref-1 holds therapeutic potential for treating nAMD.
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    Ref‐1 redox activity regulates retinal neovascularization by modulating transcriptional activation of HIF‐1α
    (Wiley, 2025) Hartman, Gabriella D.; Muniyandi, Anbukkarasi; Sishtla, Kamakshi; Kpenu, Eyram K.; Miller, William P.; Kaplan, Bryan A.; Kim, Leo A.; Liu, Sheng; Wan, Jun; Qi, Xiaoping; Boulton, Michael E.; Kelley, Mark R.; Corson, Timothy W.; Ophthalmology, School of Medicine
    Retinal neovascularization impairs visual function and is a hallmark of several neovascular eye diseases, including retinopathy of prematurity (ROP) and proliferative diabetic retinopathy (PDR). Current treatments include intravitreal injections of anti-vascular endothelial growth factor (VEGF) biologics, but these therapeutics are often accompanied by high treatment burden and resistance to therapy. Prior studies indicate that APE1/Ref-1, a multifunctional protein with both endonuclease (APE1) and redox-mediated transcriptional regulatory activity (Ref-1), activates multiple pro-angiogenic and pro-inflammatory signaling pathways by chemically reducing key cysteine residues in transcription factors, thereby activating them. Here, we investigated the previously unexplored role of Ref-1 in retinal neovascularization. We demonstrate that Ref-1 is highly expressed in endothelial cells in human PDR and in the oxygen-induced retinopathy (OIR) mouse model of retinal neovascularization. Ref-1 is also highly expressed in microglia and astrocytes in OIR. A small molecule Ref-1 redox inhibitor, APX2009, decreased retinal neovascularization in OIR after systemic delivery. In vitro, hypoxic endothelial cells did not exhibit upregulation of Ref-1 but rather increased Ref-1 nuclear localization. APX2009 decreased hypoxic endothelial cell proliferation and HIF-1α transcriptional activation. Thus, Ref-1 redox activity may be a novel therapeutic target for the treatment of retinal neovascularization, making APX2009 a promising systemic therapeutic approach for the treatment of vascular retinopathies such as ROP and PDR.
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    Retinal dysfunction in APOE4 knock‐in mouse model of Alzheimer's disease
    (Wiley, 2025) Abhyankar, Surabhi D.; Luo, Qianyi; Hartman, Gabriella D.; Mahajan, Neha; Corson, Timothy W.; Oblak, Adrian L.; Lamb, Bruce T.; Bhatwadekar, Ashay D.; Ophthalmology, School of Medicine
    Introduction: Late-onset Alzheimer's Disease (LOAD) is the predominant form of Alzheimer's disease (AD), and apolipoprotein E (APOE) ε4 is a strong genetic risk factor for LOAD. As an integral part of the central nervous system, the retina displays a variety of abnormalities in LOAD. Our study is focused on age-dependent retinal impairments in humanized APOE4-knock-in (KI) and APOE3-KI mice developed by the Model Organism Development and Evaluation for Late-Onset Alzheimer's Disease (MODEL-AD) consortium. Methods: All the experiments were performed on 52- to 57-week-old mice. The retina was assessed by optical coherence tomography, fundoscopy, fluorescein angiography, electroretinography, optomotor response, gliosis, and neuroinflammation. mRNA sequencing was performed to find molecular pathways. Results: APOE4-KI mice showed impaired retinal structure, vasculature, function, vision, increased gliosis and neuroinflammation, and downregulation of synaptogenesis. Discussion: The APOE ε4 allele is associated with increased susceptibility to retinal degeneration compared to the APOE ε3 allele. Highlights: Apolipoprotein E (APOE)4 mice exhibit structural and functional deficits of the retina. The retinal defects in APOE4 mice are attributed to increased neuroinflammation. APOE4 mice show a unique retinal transcriptome, yet with key brain similarities. The retina offers a non-invasive biomarker for the detection and monitoring of Alzheimer's disease.