1
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Gao X, Campasino K, Yourick MR, Cao Y, Yourick JJ, Sprando RL. Oxidative DNA damage contributes to usnic acid-induced toxicity in human induced pluripotent stem cell-derived hepatocytes. J Appl Toxicol 2024; 44:1329-1346. [PMID: 38724177 DOI: 10.1002/jat.4620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 12/01/2023] [Accepted: 12/03/2023] [Indexed: 08/16/2024]
Abstract
Dietary supplements containing usnic acid have been increasingly marketed for weight loss over the past decades, even though incidences of severe hepatotoxicity and acute liver failure due to their overuse have been reported. To date, the toxic mechanism of usnic acid-induced liver injury at the molecular level still remains to be fully elucidated. Here, we conducted a transcriptomic study on usnic acid using a novel in vitro hepatotoxicity model employing human induced pluripotent stem cell (iPSC)-derived hepatocytes. Treatment with 20 μM usnic acid for 24 h caused 4272 differentially expressed genes (DEGs) in the cells. Ingenuity Pathway Analysis (IPA) based on the DEGs and gene set enrichment analysis (GSEA) using the whole transcriptome expression data concordantly revealed several signaling pathways and biological processes that, when taken together, suggest that usnic acid caused oxidative stress and DNA damage in the cells, which further led to cell cycle arrest and eventually resulted in cell death through apoptosis. These transcriptomic findings were subsequently corroborated by a variety of cellular assays, including reactive oxygen species (ROS) generation and glutathione (GSH) depletion, DNA damage (pH2AX detection and 8-hydroxy-2'-deoxyguanosine [8-OH-dg] assay), cell cycle analysis, and caspase 3/7 activity. Collectively, the results of the current study accord with previous in vivo and in vitro findings, provide further evidence that oxidative stress-caused DNA damage contributes to usnic acid-induced hepatotoxicity, shed new light on molecular mechanisms of usnic acid-induced hepatotoxicity, and demonstrate the usefulness of iPSC-derived hepatocytes as an in vitro model for hepatotoxicity testing and prediction.
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Affiliation(s)
- Xiugong Gao
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland, USA
| | - Kayla Campasino
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland, USA
| | - Miranda R Yourick
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland, USA
| | - Yu Cao
- Biostatistics and Bioinformatics Staff, Office of Analytics and Outreach, Center for Food Safety and Applied Nutrition, U. S. Food and Drug Administration, College Park, Maryland, USA
| | - Jeffrey J Yourick
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland, USA
| | - Robert L Sprando
- Division of Toxicology, Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, Maryland, USA
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2
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Millington-Ward S, Palfi A, Shortall C, Finnegan LK, Bargroff E, Post IJM, Maguire J, Irnaten M, O′Brien C, Kenna PF, Chadderton N, Farrar GJ. AAV-NDI1 Therapy Provides Significant Benefit to Murine and Cellular Models of Glaucoma. Int J Mol Sci 2024; 25:8876. [PMID: 39201561 PMCID: PMC11354491 DOI: 10.3390/ijms25168876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2024] [Revised: 08/02/2024] [Accepted: 08/04/2024] [Indexed: 09/02/2024] Open
Abstract
Glaucoma, a leading cause of blindness, is a multifactorial condition that leads to progressive loss of retinal ganglion cells (RGCs) and vision. Therapeutic interventions based on reducing ocular hypertension are not always successful. Emerging features of glaucoma include mitochondrial dysfunction and oxidative stress. In the current study, NDI1-based gene therapy, which improves mitochondrial function and reduces reactive oxygen species, was delivered intraocularly via an adeno-associated viral vector (AAV). This AAV-NDI1 therapy protected RGCs from cell death in treated (1552.4 ± 994.0 RGCs/mm2) versus control eyes (1184.4 ± 978.4 RGCs/mm2, p < 0.05) in aged DBA/2J mice, a murine model of glaucoma. The photonegative responses (PhNRs) of RGCs were also improved in treated (6.4 ± 3.3 µV) versus control eyes (5.0 ± 3.1 µV, p < 0.05) in these mice. AAV-NDI1 also provided benefits in glaucomatous human lamina cribrosa (LC) cells by significantly increasing basal and maximal oxygen consumption rates and ATP production in these cells. Similarly, NDI1 therapy significantly protected H2O2-insulted primary porcine LC cells from oxidative stress. This study highlights the potential utility of NDI1 therapies and the benefits of improving mitochondrial function in the treatment of glaucoma.
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Affiliation(s)
- Sophia Millington-Ward
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - Arpad Palfi
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - Ciara Shortall
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - Laura K. Finnegan
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - Ethan Bargroff
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - Iris J. M. Post
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - John Maguire
- The Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin 2, D02XK51 Dublin, Ireland;
| | - Mustapha Irnaten
- UCD Clinical Research Centre, Mater Misericordiae University Hospital, Dublin 7, D07K201 Dublin, Ireland; (M.I.); (C.O.)
| | - Colm O′Brien
- UCD Clinical Research Centre, Mater Misericordiae University Hospital, Dublin 7, D07K201 Dublin, Ireland; (M.I.); (C.O.)
| | - Paul F. Kenna
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
- The Research Foundation, Royal Victoria Eye and Ear Hospital, Dublin 2, D02XK51 Dublin, Ireland;
| | - Naomi Chadderton
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
| | - G. Jane Farrar
- The School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, D02VF25 Dublin, Ireland; (A.P.); (C.S.); (L.K.F.); (E.B.); (I.J.M.P.); (P.F.K.); (G.J.F.)
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3
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Daka Q, Neziri B, Lindner E, Azuara Blanco A. Metformin in Glaucoma Treatment. J Glaucoma 2024; 33:387-393. [PMID: 38536124 DOI: 10.1097/ijg.0000000000002387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Accepted: 03/07/2024] [Indexed: 06/01/2024]
Abstract
PRCIS Rigorous trials are essential to develop comprehensive treatment strategies that fully exploit the therapeutic potential of metformin in the treatment of glaucoma. OBJECTIVE The objective of this study was to evaluate the potentially beneficial effect of metformin on glaucoma risk factors and to investigate the underlying mechanisms. The aim is to contribute to the development of new treatment strategies for glaucoma. METHODS We searched for studies that assessed the effects of metformin on glaucoma risk factors and the associated underlying mechanisms. Our search included electronic databases such as PUBMED, EMBASE, and clinicaltrials.gov. RESULTS Unfortunately, we did not find any clinical trials that specifically investigated the impact of metformin on glaucoma. However, data from experimental studies demonstrated the capability of metformin to modulate various pathways that could contribute to neuroprotection in glaucoma. CONCLUSION In order to develop comprehensive treatment strategies that fully exploit the therapeutic potential of metformin in the treatment of glaucoma, rigorous trials are essential. These studies are necessary to demonstrate both the safety and efficacy of metformin in the context of glaucoma treatment.
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Affiliation(s)
- Qëndresë Daka
- Department of Pathophysiology, Medical Faculty, University of Prishtina, Prishtinë, Kosovo
- Department of Ophthalmology, University Clinical Centre of Kosova, Prishtinë, Kosovo
| | - Burim Neziri
- Department of Pathophysiology, Medical Faculty, University of Prishtina, Prishtinë, Kosovo
| | - Ewald Lindner
- Department of Ophthalmology, Medical University of Granz, Auenbruggerplatz, Granz, Austria
| | - Augusto Azuara Blanco
- Centre for Public Health, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, Belfast, UK
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4
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Pitha I, Du L, Nguyen TD, Quigley H. IOP and glaucoma damage: The essential role of optic nerve head and retinal mechanosensors. Prog Retin Eye Res 2024; 99:101232. [PMID: 38110030 PMCID: PMC10960268 DOI: 10.1016/j.preteyeres.2023.101232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 12/10/2023] [Accepted: 12/11/2023] [Indexed: 12/20/2023]
Abstract
There are many unanswered questions on the relation of intraocular pressure to glaucoma development and progression. IOP itself cannot be distilled to a single, unifying value, because IOP level varies over time, differs depending on ocular location, and can be affected by method of measurement. Ultimately, IOP level creates mechanical strain that affects axonal function at the optic nerve head which causes local extracellular matrix remodeling and retinal ganglion cell death - hallmarks of glaucoma and the cause of glaucomatous vision loss. Extracellular tissue strain at the ONH and lamina cribrosa is regionally variable and differs in magnitude and location between healthy and glaucomatous eyes. The ultimate targets of IOP-induced tissue strain in glaucoma are retinal ganglion cell axons at the optic nerve head and the cells that support axonal function (astrocytes, the neurovascular unit, microglia, and fibroblasts). These cells sense tissue strain through a series of signals that originate at the cell membrane and alter cytoskeletal organization, migration, differentiation, gene transcription, and proliferation. The proteins that translate mechanical stimuli into molecular signals act as band-pass filters - sensing some stimuli while ignoring others - and cellular responses to stimuli can differ based on cell type and differentiation state. Therefore, to fully understand the IOP signals that are relevant to glaucoma, it is necessary to understand the ultimate cellular targets of IOP-induced mechanical stimuli and their ability to sense, ignore, and translate these signals into cellular actions.
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Affiliation(s)
- Ian Pitha
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Center for Nanomedicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Liya Du
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thao D Nguyen
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD, USA
| | - Harry Quigley
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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5
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Deng L, Gupta V, Abyadeh M, Chitranshi N, Pushpitha K, Wu Y, Gupta V, You Y, Paulo JA, Graham SL, Mirzaei M, Haynes PA. Oxidative Stress Induced Dysfunction of Protein Synthesis in 661W Mice Photoreceptor Cells. Proteomes 2023; 11:12. [PMID: 37092453 PMCID: PMC10123756 DOI: 10.3390/proteomes11020012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Revised: 03/17/2023] [Accepted: 03/22/2023] [Indexed: 04/05/2023] Open
Abstract
Photoreceptor cells are highly susceptible to oxidative-stress-induced damage due to their high metabolic rate. Oxidative stress plays a key role in driving pathological events in several different ocular diseases, which lead to retinal degeneration and ultimately blindness. A growing number of studies have been performed to understand downstream events caused by ROS induced oxidative stress in photoreceptor cells; however, the underlying mechanisms of ROS toxicity are not fully understood. To shed light on ROS induced downstream pathological events, we employed a tandem mass tag (TMT) labelling-based quantitative mass-spectrometric approach to determine proteome changes in 661W photoreceptor cells following oxidative stress induction via the application of different concentrations of H2O2 at different time points. Overall, 5920 proteins were identified and quantified, and 450 differentially expressed proteins (DEPs) were identified, which were altered in a dose and time dependent manner in all treatment groups compared to the control group. These proteins were involved in several biological pathways, including spliceosome and ribosome response, activated glutathione metabolism, decreased ECM-receptor interaction, oxidative phosphorylation, abnormally regulated lysosome, apoptosis, and ribosome biogenesis. Our results highlighted ECM receptor interaction, oxidative phosphorylation and spliceosome pathways as the major targets of oxidative stress that might mediate vascular dysfunction and cellular senescence.
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Affiliation(s)
- Liting Deng
- Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Vivek Gupta
- Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Macquarie Park, NSW 2109, Australia
| | | | - Nitin Chitranshi
- Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Kanishka Pushpitha
- Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Yunqi Wu
- Australian Proteome Analysis Facility, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Veer Gupta
- School of Medicine, Deakin University, Geelong, VIC 3220, Australia
| | - Yuyi You
- Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Joao A. Paulo
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Stuart L. Graham
- Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Mehdi Mirzaei
- Macquarie Medical School, Faculty of Medicine, Health and Human Sciences, Macquarie University, Macquarie Park, NSW 2109, Australia
| | - Paul A. Haynes
- School of Natural Sciences, Macquarie University, Macquarie Park, NSW 2109, Australia
- Biomolecular Discovery Research Centre, Macquarie University, Macquarie Park, NSW 2109, Australia
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6
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Irnaten M, O’Brien CJ. Calcium-Signalling in Human Glaucoma Lamina Cribrosa Myofibroblasts. Int J Mol Sci 2023; 24:ijms24021287. [PMID: 36674805 PMCID: PMC9862249 DOI: 10.3390/ijms24021287] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/20/2022] [Accepted: 01/01/2023] [Indexed: 01/11/2023] Open
Abstract
Glaucoma is one of the most common causes of treatable visual impairment in the developed world, affecting approximately 64 million people worldwide, some of whom will be bilaterally blind from irreversible optic nerve damage. The optic nerve head is a key site of damage in glaucoma where there is fibrosis of the connective tissue in the lamina cribrosa (LC) extracellular matrix. As a ubiquitous second messenger, calcium (Ca2+) can interact with various cellular proteins to regulate multiple physiological processes and contribute to a wide range of diseases, including cancer, fibrosis, and glaucoma. Our research has shown evidence of oxidative stress, mitochondrial dysfunction, an elevated expression of Ca2+ entry channels, Ca2+-dependent pumps and exchangers, and an abnormal rise in cytosolic Ca2+ in human glaucomatous LC fibroblast cells. We have evidence that this increase is dependent on Ca2+ entry channels located in the plasma membrane, and its release is from internal stores in the endoplasmic reticulum (ER), as well as from the mitochondria. Here, we summarize some of the molecular Ca2+-dependent mechanisms related to this abnormal Ca2+-signalling in human glaucoma LC cells, with a view toward identifying potential therapeutic targets for ongoing optic neuropathy.
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Nsiah NY, Inman DM. Destabilizing COXIV in Müller Glia Increases Retinal Glycolysis and Alters Scotopic Electroretinogram. Cells 2022; 11:cells11233756. [PMID: 36497016 PMCID: PMC9737073 DOI: 10.3390/cells11233756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/17/2022] [Accepted: 11/22/2022] [Indexed: 11/25/2022] Open
Abstract
Müller glia (MG), the principal glial cell of the retina, have a metabolism that defies categorization into glycolytic versus oxidative. We showed that MG mount a strong hypoxia response to ocular hypertension, raising the question of their relative reliance on mitochondria for function. To explore the role of oxidative phosphorylation (OXPHOS) in MG energy production in vivo, we generated and characterized adult mice in which MG have impaired cytochrome c oxidase (COXIV) activity through knockout of the COXIV constituent COX10. Histochemistry and protein analysis showed that COXIV protein levels were significantly lower in knockout mouse retina compared to control. Loss of COXIV activity in MG did not induce structural abnormalities, though oxidative stress was increased. Electroretinography assessment showed that knocking out COX10 significantly impaired scotopic a- and b-wave responses. Inhibiting mitochondrial respiration in MG also altered the retinal glycolytic profile. However, blocking OXPHOS in MG did not significantly exacerbate retinal ganglion cell (RGC) loss or photopic negative response after ocular hypertension (OHT). These results suggest that MG were able to compensate for reduced COXIV stability by maintaining fundamental processes, but changes in retinal physiology and metabolism-associated proteins indicate subtle changes in MG function.
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8
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Vallabh NA, Armstrong J, Czanner G, McDonagh B, Choudhary A, Criddle DN, Willoughby CE. Evidence of impaired mitochondrial cellular bioenergetics in ocular fibroblasts derived from glaucoma patients. Free Radic Biol Med 2022; 189:102-110. [PMID: 35872337 DOI: 10.1016/j.freeradbiomed.2022.07.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2022] [Revised: 06/29/2022] [Accepted: 07/12/2022] [Indexed: 11/20/2022]
Abstract
Glaucoma is a progressive optic neuropathy characterized by the neurodegeneration of the retinal ganglion cells (RGCs) resulting in irreversible visual impairment and eventual blindness. RGCs are extremely susceptible to mitochondrial compromise due to their marked bioenergetic requirements and morphology. There is increasing interest in therapies targeting mitochondrial health as a method of preventing visual loss in managing glaucoma. The bioenergetic profile of Tenon's ocular fibroblasts from glaucoma patients and controls was investigated using the Seahorse XF24 analyser. Impaired mitochondrial cellular bioenergetics was detected in glaucomatous ocular fibroblasts including basal respiration, maximal respiration and spare capacity. Spare respiratory capacity levels reflect mitochondrial bio-energetic adaptability in response to pathophysiological stress. Basal oxidative stress was elevated in glaucomatous Tenon's ocular fibroblasts and hydrogen peroxide (H2O2) induced reactive oxygen species (ROS) simulated the glaucomatous condition in normal Tenon's ocular fibroblasts. This work supports the role of therapeutic interventions to target oxidative stress or provide mitochondrial energetic support in glaucoma.
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Affiliation(s)
- Neeru A Vallabh
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L69 3BX, United Kingdom; St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, L7 8XP, United Kingdom
| | - Jane Armstrong
- Institute of Systems, Molecular and Integrative Biology, Biosciences Building, University of Liverpool, Liverpool, L69 7BE, United Kingdom
| | - Gabriela Czanner
- School of Computer Science and Mathematics, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, United Kingdom; Faculty of Informatics and Information Technology, Slovak University of Technology, 842 16, Bratislava, Slovakia
| | - Brian McDonagh
- Discipline of Physiology, School of Medicine, National University of Ireland, Galway, Ireland
| | - Anshoo Choudhary
- St. Paul's Eye Unit, Royal Liverpool University Hospital, Liverpool, L7 8XP, United Kingdom
| | - David N Criddle
- Institute of Systems, Molecular and Integrative Biology, Biosciences Building, University of Liverpool, Liverpool, L69 7BE, United Kingdom
| | - Colin E Willoughby
- Department of Eye and Vision Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool, L69 3BX, United Kingdom; Genomic Medicine, Biomedical Sciences Research Institute, Ulster University, Coleraine, BT52 1SA, United Kingdom.
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9
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Pappenhagen N, Yin E, Morgan AB, Kiehlbauch CC, Inman DM. Stretch stress propels glutamine dependency and glycolysis in optic nerve head astrocytes. Front Neurosci 2022; 16:957034. [PMID: 35992925 PMCID: PMC9389405 DOI: 10.3389/fnins.2022.957034] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 07/12/2022] [Indexed: 11/21/2022] Open
Abstract
Glaucoma is an optic neuropathy that leads to irreversible blindness, the most common subtype of which is typified by a chronic increase in intraocular pressure that promotes a stretch injury to the optic nerve head. In rodents, the predominant glial cell in this region is the optic nerve head astrocyte that provides axons with metabolic support, likely by releasing lactate produced through astrocytic glycolysis. Our primary hypothesis is that stretching of the optic nerve head astrocytes alters their metabolic activity, thereby advancing glaucoma-associated degeneration by compromising the metabolic support that the astrocytes provide to the axons in the optic nerve head. Metabolic changes in optic nerve head astrocytes were investigated by subjecting them to 24 h of 12% biaxial stretch at 1 Hz then measuring the cells’ bioenergetics using a Seahorse XFe24 Analyzer. We observed significant glycolytic and respiratory activity differences between control and stretched cells, including greater extracellular acidification and lower ATP-linked respiration, yet higher maximal respiration and spare capacity in stretched optic nerve head astrocytes. We also determined that both control and stretched optic nerve head astrocytes displayed a dependency for glutamine over pyruvate or long-chain fatty acids for fuel. The increased use of glycolysis as indicated by the extracellular acidification rate, concomitant with a dependency on glutamine, suggests the need to replenish NAD + for continued glycolysis and provision of carbon for TCA cycle intermediates. Stretch alters optic nerve astrocyte bioenergetics to support an increased demand for internal and external energy.
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Affiliation(s)
- Nathaniel Pappenhagen
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Eric Yin
- Texas College of Osteopathic Medicine, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Autumn B. Morgan
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Charles C. Kiehlbauch
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, United States
| | - Denise M. Inman
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX, United States
- *Correspondence: Denise M. Inman,
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10
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Jassim AH, Fan Y, Pappenhagen N, Nsiah NY, Inman DM. Oxidative Stress and Hypoxia Modify Mitochondrial Homeostasis During Glaucoma. Antioxid Redox Signal 2021; 35:1341-1357. [PMID: 33736457 PMCID: PMC8817702 DOI: 10.1089/ars.2020.8180] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Aims: Cellular response to hypoxia can include transition from respiration to glycolysis via upregulation of glycolytic enzymes and transporters, as well as mitophagy induction to eliminate surplus mitochondria. Our purpose was to evaluate the impact of hypoxia-inducible factor-1α (HIF-1α) stabilization on mitochondrial homeostasis and oxidative stress in a chronic model of glaucoma. Results: Retina and optic nerve (ON) were evaluated from young and aged DBA/2J (D2) glaucoma model mice and the control strain, the DBA/2-Gpnmb+. Hypoxic retinal ganglion cells (RGCs) were observed in young and aged D2 retina, with a significant increase in HIF-1α protein in the aged D2 retina. Reactive oxygen species observed in young D2 retina and ON were followed by significant decreases in antioxidant capacity in aged D2 retina and ON. HIF-1α targets such as neuron-specific glucose transporter-3 and lactate dehydrogenase were decreased or unchanged, respectively, in aged D2 retina despite an increased hypoxia response in RGCs. Mitochondrial mass was decreased in aged D2 retina concomitant with decreased mitochondrially encoded electron transport chain transcripts despite a stable nuclear-encoded TFAM (mitochondrial transcription factor), suggesting a breakdown in the nuclear-mitochondrial communication. Decreased mitophagy-associated proteins p62 and Rheb were observed in aged D2 retina, although p62 was significantly increased in the aged D2 ON. Innovation and Conclusion: The increased reactive oxygen species concomitant with HIF-1α upregulation despite reduced glucose transporters, mis-match of nuclear- and mitochondrial-encoded transcripts, and signs of reduced mitophagy suggest that retinas from D2 mice with chronic intraocular pressure elevation transition to pseudohypoxia without consistent metabolic reprogramming before significant RGC loss. Antioxid. Redox Signal. 35, 1341-1357.
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Affiliation(s)
- Assraa Hassan Jassim
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, Rootstown, Ohio, USA
| | - Yan Fan
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Nathaniel Pappenhagen
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, USA
- Kent State University School of Biomedical Sciences, Kent, Ohio, USA
| | - Nana Yaa Nsiah
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, USA
| | - Denise M. Inman
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, USA
- Address correspondence to: Dr. Denise M. Inman, Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center, 3500 Camp Bowie Boulevard, Fort Worth, TX 76107, USA
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11
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Geva M, Gershoni-Emek N, Naia L, Ly P, Mota S, Rego AC, Hayden MR, Levin LA. Neuroprotection of retinal ganglion cells by the sigma-1 receptor agonist pridopidine in models of experimental glaucoma. Sci Rep 2021; 11:21975. [PMID: 34753986 PMCID: PMC8578336 DOI: 10.1038/s41598-021-01077-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 10/20/2021] [Indexed: 12/21/2022] Open
Abstract
Optic neuropathies such as glaucoma are characterized by retinal ganglion cell (RGC) degeneration and death. The sigma-1 receptor (S1R) is an attractive target for treating optic neuropathies as it is highly expressed in RGCs, and its absence causes retinal degeneration. Activation of the S1R exerts neuroprotective effects in models of retinal degeneration. Pridopidine is a highly selective and potent S1R agonist in clinical development. We show that pridopidine exerts neuroprotection of retinal ganglion cells in two different rat models of glaucoma. Pridopidine strongly binds melanin, which is highly expressed in the retina. This feature of pridopidine has implications to its ocular distribution, bioavailability, and effective dose. Mitochondria dysfunction is a key contributor to retinal ganglion cell degeneration. Pridopidine rescues mitochondrial function via activation of the S1R, providing support for the potential mechanism driving its neuroprotective effect in retinal ganglion cells.
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Affiliation(s)
| | | | - Luana Naia
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- Department of Neurobiology, Care Science and Society, Karolinska Institutet, Stockholm, Sweden
| | - Philip Ly
- The Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - Sandra Mota
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Ana Cristina Rego
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
- FMUC-Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Michael R Hayden
- Prilenia Therapeutics, Herzliya, Israel
- The Centre for Molecular Medicine and Therapeutics, BC Children's Hospital Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - Leonard A Levin
- Department of Ophthalmology and Visual Sciences, McGill University, Montreal, Canada.
- Department of Neurology and Neurosurgery, McGill University, Montreal, Canada.
- Montreal Neurological Institute, McGill University, Montreal, Canada.
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12
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Cleland NRW, Al-Juboori SI, Dobrinskikh E, Bruce KD. Altered substrate metabolism in neurodegenerative disease: new insights from metabolic imaging. J Neuroinflammation 2021; 18:248. [PMID: 34711251 PMCID: PMC8555332 DOI: 10.1186/s12974-021-02305-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 10/21/2021] [Indexed: 12/13/2022] Open
Abstract
Neurodegenerative diseases (NDs), such as Alzheimer's disease (AD), Parkinson's disease (PD) and multiple sclerosis (MS), are relatively common and devastating neurological disorders. For example, there are 6 million individuals living with AD in the United States, a number that is projected to grow to 14 million by the year 2030. Importantly, AD, PD and MS are all characterized by the lack of a true disease-modifying therapy that is able to reverse or halt disease progression. In addition, the existing standard of care for most NDs only addresses the symptoms of the disease. Therefore, alternative strategies that target mechanisms underlying the neuropathogenesis of disease are much needed. Recent studies have indicated that metabolic alterations in neurons and glia are commonly observed in AD, PD and MS and lead to changes in cell function that can either precede or protect against disease onset and progression. Specifically, single-cell RNAseq studies have shown that AD progression is tightly linked to the metabolic phenotype of microglia, the key immune effector cells of the brain. However, these analyses involve removing cells from their native environment and performing measurements in vitro, influencing metabolic status. Therefore, technical approaches that can accurately assess cell-specific metabolism in situ have the potential to be transformative to our understanding of the mechanisms driving AD. Here, we review our current understanding of metabolism in both neurons and glia during homeostasis and disease. We also evaluate recent advances in metabolic imaging, and discuss how emerging modalities, such as fluorescence lifetime imaging microscopy (FLIM) have the potential to determine how metabolic perturbations may drive the progression of NDs. Finally, we propose that the temporal, regional, and cell-specific characterization of brain metabolism afforded by FLIM will be a critical first step in the rational design of metabolism-focused interventions that delay or even prevent NDs.
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Affiliation(s)
- Nicholas R W Cleland
- Endocrinology, Metabolism and Diabetes, Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, USA
- School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, USA
| | - Saif I Al-Juboori
- Section of Neonatology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, USA
| | - Evgenia Dobrinskikh
- Section of Neonatology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, USA
- Division of Pulmonary Sciences and Critical Care, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, USA
| | - Kimberley D Bruce
- Endocrinology, Metabolism and Diabetes, Division of Endocrinology, Metabolism and Diabetes, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, USA.
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13
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Fibrotic Changes to Schlemm's Canal Endothelial Cells in Glaucoma. Int J Mol Sci 2021; 22:ijms22179446. [PMID: 34502356 PMCID: PMC8431431 DOI: 10.3390/ijms22179446] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 08/27/2021] [Accepted: 08/29/2021] [Indexed: 12/21/2022] Open
Abstract
Previous studies have shown that glaucomatous Schlemm’s canal endothelial cells (gSCECs) are stiffer and associated with reduced porosity and increased extracellular matrix (ECM) material compared to SCECs from healthy individuals. We hypothesised that Schlemm’s canal (SC) cell stiffening was a function of fibrotic changes occurring at the inner wall of SC in glaucoma. This study was performed in primary cell cultures isolated from the SC lumen of human donor eyes. RNA and protein quantification of both fibrotic and endothelial cell markers was carried out on both healthy and gSCECs. Functional assays to assess cell density, size, migration, proliferation, and mitochondrial function of these cells were also carried out. Indeed, we found that gSCECs deviate from typical endothelial cell characteristics and exhibit a more fibrotic phenotype. For example, gSCECs expressed significantly higher protein levels of the fibrotic markers α-SMA, collagen I-α1, and fibronectin, as well as significantly increased protein expression of TGFβ-2, the main driver of fibrosis, compared to healthy SCECs. Interestingly, we observed a significant increase in protein expression of endothelial marker VE-cadherin in gSCECs, compared to healthy SCECs. gSCECs also appeared to be significantly larger, and surprisingly proliferate and migrate at a significantly higher rate, as well as showing significantly reduced mitochondrial activity, compared to healthy SCECs.
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14
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Hurley DJ, Irnaten M, O’Brien C. Metformin and Glaucoma-Review of Anti-Fibrotic Processes and Bioenergetics. Cells 2021; 10:cells10082131. [PMID: 34440899 PMCID: PMC8394782 DOI: 10.3390/cells10082131] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/13/2021] [Accepted: 08/16/2021] [Indexed: 02/06/2023] Open
Abstract
Glaucoma is the leading cause of irreversible blindness globally. With an aging population, disease incidence will rise with an enormous societal and economic burden. The treatment strategy revolves around targeting intraocular pressure, the principle modifiable risk factor, to slow progression of disease. However, there is a clear unmet clinical need to find a novel therapeutic approach that targets and halts the retinal ganglion cell (RGC) degeneration that occurs with fibrosis. RGCs are highly sensitive to metabolic fluctuations as a result of multiple stressors and thus their viability depends on healthy mitochondrial functioning. Metformin, known for its use in type 2 diabetes, has come to the forefront of medical research in multiple organ systems. Its use was recently associated with a 25% reduced risk of glaucoma in a large population study. Here, we discuss its application to glaucoma therapy, highlighting its effect on fibrotic signalling pathways, mitochondrial bioenergetics and NAD oxidation.
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Affiliation(s)
- Daire J. Hurley
- Department of Ophthalmology, Mater Misericordiae University Hospital, Eccles Street, D07 R2WY Dublin, Ireland; (M.I.); (C.O.)
- School of Medicine, University College Dublin, Belfield, D04 V1W8 Dublin, Ireland
- Correspondence:
| | - Mustapha Irnaten
- Department of Ophthalmology, Mater Misericordiae University Hospital, Eccles Street, D07 R2WY Dublin, Ireland; (M.I.); (C.O.)
| | - Colm O’Brien
- Department of Ophthalmology, Mater Misericordiae University Hospital, Eccles Street, D07 R2WY Dublin, Ireland; (M.I.); (C.O.)
- School of Medicine, University College Dublin, Belfield, D04 V1W8 Dublin, Ireland
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