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Brandli A, Vessey KA, Fletcher EL. The contribution of pattern recognition receptor signalling in the development of age related macular degeneration: the role of toll-like-receptors and the NLRP3-inflammasome. J Neuroinflammation 2024; 21:64. [PMID: 38443987 PMCID: PMC10913318 DOI: 10.1186/s12974-024-03055-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 02/26/2024] [Indexed: 03/07/2024] Open
Abstract
Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss, characterised by the dysfunction and death of the photoreceptors and retinal pigment epithelium (RPE). Innate immune cell activation and accompanying para-inflammation have been suggested to contribute to the pathogenesis of AMD, although the exact mechanism(s) and signalling pathways remain elusive. Pattern recognition receptors (PRRs) are essential activators of the innate immune system and drivers of para-inflammation. Of these PRRs, the two most prominent are (1) Toll-like receptors (TLR) and (2) NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3)-inflammasome have been found to modulate the progression of AMD. Mutations in TLR2 have been found to be associated with an increased risk of developing AMD. In animal models of AMD, inhibition of TLR and NLRP3 has been shown to reduce RPE cell death, inflammation and angiogenesis signalling, offering potential novel treatments for advanced AMD. Here, we examine the evidence for PRRs, TLRs2/3/4, and NLRP3-inflammasome pathways in macular degeneration pathogenesis.
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Affiliation(s)
- Alice Brandli
- Department of Anatomy and Physiology, The University of Melbourne, Grattan St, Parkville, Victoria, 3010, Australia
- Roche Pharma Research and Early Development, F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Kirstan A Vessey
- Department of Anatomy and Physiology, The University of Melbourne, Grattan St, Parkville, Victoria, 3010, Australia
| | - Erica L Fletcher
- Department of Anatomy and Physiology, The University of Melbourne, Grattan St, Parkville, Victoria, 3010, Australia.
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Liu J, Copland DA, Clare AJ, Gorski M, Richards BT, Scott L, Theodoropoulou S, Greferath U, Cox K, Bell OH, Ou K, Powell JLB, Wu J, Robles LM, Li Y, Nicholson LB, Coffey PJ, Fletcher EL, Guymer R, Radeke MJ, Heid IM, Hageman GS, Chan YK, Dick AD. Replenishing Age-Related Decline of IRAK-M Expression in Retinal Pigment Epithelium Attenuates Outer Retinal Degeneration. bioRxiv 2023:2023.09.27.559733. [PMID: 37808640 PMCID: PMC10557650 DOI: 10.1101/2023.09.27.559733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Unchecked, chronic inflammation is a constitutive component of age-related diseases, including age-related macular degeneration (AMD). Here we identified interleukin-1 receptor-associated kinase (IRAK)-M as a key immunoregulator in retinal pigment epithelium (RPE) that declines with age. Rare genetic variants of IRAK-M increased the likelihood of AMD. IRAK-M expression in RPE declined with age or oxidative stress and was further reduced in AMD. IRAK-M-deficient mice exhibited increased incidence of outer retinal degeneration at earlier ages, which was further exacerbated by oxidative stressors. The absence of IRAK-M disrupted RPE cell homeostasis, including compromised mitochondrial function, cellular senescence, and aberrant cytokine production. IRAK-M overexpression protected RPE cells against oxidative or immune stressors. Subretinal delivery of AAV-expressing IRAK-M rescued light-induced outer retinal degeneration in wild-type mice and attenuated age-related spontaneous retinal degeneration in IRAK-M-deficient mice. Our data support that replenishment of IRAK-M expression may redress dysregulated pro-inflammatory processes in AMD, thereby treating degeneration.
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Affiliation(s)
- Jian Liu
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - David A. Copland
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Alison J. Clare
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Mathias Gorski
- Department of Genetic Epidemiology, University of Regensburg, Regensburg, Germany
| | - Burt T. Richards
- Sharon Eccles Steele Center for Translational Medicine, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Louis Scott
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Sofia Theodoropoulou
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Ursula Greferath
- Department of Anatomy and Physiology, University of Melbourne, Victoria, Australia
| | - Katherine Cox
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Oliver H. Bell
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Kepeng Ou
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Jenna Le Brun Powell
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Jiahui Wu
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Luis Martinez Robles
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Yingxin Li
- Translational Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Lindsay B. Nicholson
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
| | - Peter J. Coffey
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Erica L. Fletcher
- Department of Anatomy and Physiology, University of Melbourne, Victoria, Australia
| | - Robyn Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia
| | - Monte J. Radeke
- Neuroscience Research Institute, University of California, Santa Barbara, California, United States
| | - Iris M. Heid
- Department of Genetic Epidemiology, University of Regensburg, Regensburg, Germany
| | - Gregory S. Hageman
- Sharon Eccles Steele Center for Translational Medicine, John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Ying Kai Chan
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, Massachusetts, United States
| | - Andrew D. Dick
- Academic Unit of Ophthalmology, Bristol Medical School, University of Bristol, Bristol, United Kingdom
- School of Cellular and Molecular Medicine, University of Bristol, Bristol, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
- National Institute for Health Research Biomedical Research Centre, Moorfields Eye Hospital, London, United Kingdom
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Ma JY, Greferath U, Wong JH, Fothergill LJ, Jobling AI, Vessey KA, Fletcher EL. Aging induces cell loss and a decline in phagosome processing in the mouse retinal pigment epithelium. Neurobiol Aging 2023; 128:1-16. [PMID: 37130462 DOI: 10.1016/j.neurobiolaging.2023.03.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 02/10/2023] [Accepted: 03/03/2023] [Indexed: 03/14/2023]
Abstract
Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss and dysfunction in the retinal pigment epithelium (RPE) with age is known to contribute to disease development. The aim of this study was to investigate how the C57BL/6J mouse RPE changes with age. RPE structure was found to change with age and eccentricity, with cell size increasing, nuclei lost, and tight junctions altered in the peripheral retina. Phagocytosis of photoreceptor outer segments (POS) by the RPE was investigated using gene expression analysis and histology. RNA-Seq transcriptomic gene profiling of the RPE showed a downregulation of genes involved in phagosome processing and histological analysis showed a decline in phagosome-lysosome association in the aged tissue. In addition, failures in the autophagy pathway that modulates intracellular waste degradation were observed in the aged RPE tissue. These findings highlight that RPE cell loss and slowing of POS processing contribute to RPE dysfunction with age and may predispose the aging eye to AMD development.
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Fletcher EL, Dixon MA, Mills SA, Jobling AI. Anomalies in neurovascular coupling during early diabetes: A review. Clin Exp Ophthalmol 2023; 51:81-91. [PMID: 36349522 PMCID: PMC10947109 DOI: 10.1111/ceo.14190] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Revised: 10/26/2022] [Accepted: 11/04/2022] [Indexed: 11/11/2022]
Abstract
Diabetic retinopathy is the most feared complication for those with diabetes. Although visible vascular pathology traditionally defines the management of this condition, it is now recognised that a range of cellular changes occur in the retina from an early stage of diabetes. One of the most significant functional changes that occurs in those with diabetes is a loss of vasoregulation in response to changes in neural activity. There are several retinal cell types that are critical for mediating so-called neurovascular coupling, including Müller cells, microglia and pericytes. Although there is a great deal of evidence that suggests that Müller cells are integral to regulating the vasculature, they only modulate part of the vascular tree, highlighting the complexity of vasoregulation within the retina. Recent studies suggest that retinal immune cells, microglia, play an important role in mediating vasoconstriction. Importantly, retinal microglia contact both the vasculature and neural synapses and induce vasoconstriction in response to neurally expressed chemokines such as fractalkine. This microglial-dependent regulation occurs via the vasomediator angiotensinogen. Diabetes alters the way microglia regulate the retinal vasculature, by increasing angiotensinogen expression, causing capillary vasoconstriction and contributing to a loss of vascular reactivity to physiological signals. This article summarises recent studies showing changes in vascular regulation during diabetes, the potential mechanisms by which this occurs and the significance of these early changes to the progression of diabetic retinopathy.
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Affiliation(s)
- Erica L. Fletcher
- Department of Anatomy and PhysiologyThe University of MelbourneMelbourneVictoriaAustralia
| | - Michael A. Dixon
- Department of Anatomy and PhysiologyThe University of MelbourneMelbourneVictoriaAustralia
| | - Samuel A. Mills
- Department of Anatomy and Developmental BiologyMonash UniversityMelbourneVictoriaAustralia
| | - Andrew I. Jobling
- Department of Anatomy and PhysiologyThe University of MelbourneMelbourneVictoriaAustralia
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Reynisson H, Kalloniatis M, Fletcher EL, Shivdasani MN, Nivison-Smith L. Loss of Müller cell glutamine synthetase immunoreactivity is associated with neuronal changes in late-stage retinal degeneration. Front Neuroanat 2023; 17:997722. [PMID: 36960036 PMCID: PMC10029270 DOI: 10.3389/fnana.2023.997722] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 01/31/2023] [Indexed: 03/09/2023] Open
Abstract
Introduction A hallmark of photoreceptor degenerations is progressive, aberrant remodeling of the surviving retinal neurons and glia following photoreceptor loss. The exact relationship between neurons and glia remodeling in this late stage of retinal degeneration, however, is unclear. This study assessed this by examining Müller cell dysfunction via glutamine synthetase immunoreactivity and its spatial association with retinal neuron subpopulations through various cell markers. Methods Aged Rd1 mice retinae (P150 - P536, n = minimum 5 per age) and control heterozygous rd1 mice retinae (P536, n = 5) were isolated, fixed and cryosectioned. Fluorescent immunolabeling of glutamine synthetase was performed and retinal areas quantified as having low glutamine synthetase immunoreactivity if proportion of labeled pixels in an area was less than two standard deviations of the mean of the total retina. Other Müller cell markers such as Sox9 and Glial fibrillary acidic protein along with neuronal cell markers Calbindin, Calretinin, recoverin, Protein kinase C-α, Glutamic acid decarboxylase 67, and Islet-1 were then quantified within areas of low and normal synthetase immunoreactivity. Results Glutamine synthetase immunoreactivity was lost as a function of age in the rd1 mouse retina (P150 - P536). Immunoreactivity of other Müller cell markers, however, were unaffected suggesting Müller cells were still present in these low glutamine synthetase immunoreactive regions. Glutamine synthetase immunoreactivity loss affected specific neuronal populations: Type 2, Type 8 cone, and rod bipolar cells, as well as AII amacrine cells based on reduced recoverin, protein kinase Ca and parvalbumin immunoreactivity, respectively. The number of cell nuclei within regions of low glutamine synthetase immunoreactivity was also reduced suggesting possible neuronal loss rather than reduced cell marker immunoreactivity. Conclusion These findings further support a strong interplay between glia-neuronal alterations in late-stage degeneration and highlight a need for future studies and consideration in intervention development.
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Affiliation(s)
- Hallur Reynisson
- School of Optometry and Vision Science, UNSW Sydney, Sydney, NSW, Australia
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia
| | - Michael Kalloniatis
- School of Optometry and Vision Science, UNSW Sydney, Sydney, NSW, Australia
- Faculty of Medicine (Optometry), Deakin University, Waurn Ponds, VIC, Australia
| | - Erica L. Fletcher
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Mohit N. Shivdasani
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, NSW, Australia
- Bionics and Bio-robotics, Tyree Foundation Institute of Health Engineering, Kensington, NSW, Australia
| | - Lisa Nivison-Smith
- School of Optometry and Vision Science, UNSW Sydney, Sydney, NSW, Australia
- *Correspondence: Lisa Nivison-Smith,
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Wong JHC, Ma JYW, Jobling AI, Brandli A, Greferath U, Fletcher EL, Vessey KA. Exploring the pathogenesis of age-related macular degeneration: A review of the interplay between retinal pigment epithelium dysfunction and the innate immune system. Front Neurosci 2022; 16:1009599. [PMID: 36408381 PMCID: PMC9670140 DOI: 10.3389/fnins.2022.1009599] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 10/12/2022] [Indexed: 07/30/2023] Open
Abstract
Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss in the older population. Classical hallmarks of early and intermediate AMD are accumulation of drusen, a waste deposit formed under the retina, and pigmentary abnormalities in the retinal pigment epithelium (RPE). When the disease progresses into late AMD, vision is affected due to death of the RPE and the light-sensitive photoreceptors. The RPE is essential to the health of the retina as it forms the outer blood retinal barrier, which establishes ocular immune regulation, and provides support for the photoreceptors. Due to its unique anatomical position, the RPE can communicate with the retinal environment and the systemic immune environment. In AMD, RPE dysfunction and the accumulation of drusen drive the infiltration of retinal and systemic innate immune cells into the outer retina. While recruited endogenous or systemic mononuclear phagocytes (MPs) contribute to the removal of noxious debris, the accumulation of MPs can also result in chronic inflammation and contribute to AMD progression. In addition, direct communication and indirect molecular signaling between MPs and the RPE may promote RPE cell death, choroidal neovascularization and fibrotic scarring that occur in late AMD. In this review, we explore how the RPE and innate immune cells maintain retinal homeostasis, and detail how RPE dysfunction and aberrant immune cell recruitment contribute to AMD pathogenesis. Evidence from AMD patients will be discussed in conjunction with data from preclinical models, to shed light on future therapeutic targets for the treatment of AMD.
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Vessey KA, Jobling AI, Tran MX, Wang AY, Greferath U, Fletcher EL. Treatments targeting autophagy ameliorate the age-related macular degeneration phenotype in mice lacking APOE (apolipoprotein E). Autophagy 2022; 18:2368-2384. [PMID: 35196199 PMCID: PMC9542759 DOI: 10.1080/15548627.2022.2034131] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Age-related macular degeneration (AMD) is a leading cause of vision loss with recent evidence indicating an important role for macroautophagy/autophagy in disease progression. In this study we investigate the efficacy of targeting autophagy for slowing dysfunction in a mouse model with features of early AMD. Mice lacking APOE (apolipoprotein E; B6.129P2-Apoetm1UncJ/Arc) and C57BL/6 J- (wild-type, WT) mice were treated with metformin or trehalose in the drinking water from 5 months of age and the ocular phenotype investigated at 13 months. Control mice received normal drinking water. APOE-control mice had reduced retinal function and thickening of Bruch’s membrane consistent with an early AMD phenotype. Immunohistochemical labeling showed reductions in MAP1LC3B/LC3 (microtubule-associated protein 1 light chain 3 beta) and LAMP1 (lysosomal-associated membrane protein 1) labeling in the photoreceptors and retinal pigment epithelium (RPE). This correlated with increased LC3-II:LC3-I ratio and alterations in protein expression in multiple autophagy pathways measured by reverse phase protein array, suggesting autophagy was slowed. Treatment of APOE-mice with metformin or trehalose ameliorated the loss of retinal function and reduced Bruch’s membrane thickening, enhancing LC3 and LAMP1 labeling in the ocular tissues and restoring LC3-II:LC3-I ratio to WT levels. Protein analysis indicated that both treatments boost ATM-AMPK driven autophagy. Additionally, trehalose increased p-MAPK14/p38 to enhance autophagy. Our study shows that treatments targeting pathways to enhance autophagy have the potential for treating early AMD and provide support for the use of metformin, which has been found to reduce the risk of AMD development in human patients.Abbreviations:AMD: age-related macular degeneration; AMPK: 5’ adenosine monophosphate-activated protein kinase APOE: apolipoprotein E; ATM: ataxia telangiectasia mutated; BCL2L1/Bcl-xL: BCL2-like 1; DAPI: 4ʹ-6-diamidino-2-phenylindole; ERG: electroretinogram; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GCL: ganglion cell layer; INL: inner nuclear layer; IPL: inner plexiform layer; IS/OS: inner and outer photoreceptor segments; LAMP1: lysosomal-associated membrane protein 1; MAP1LC3B/LC3: microtubule-associated protein 1 light chain 3 beta; MTOR: mechanistic target of rapamycin kinase; OCT: optical coherence tomography; ONL: outer nuclear layer; OPs: oscillatory potentials; p-EIF4EBP1: phosphorylated eukaryotic translation initiation factor 4E binding protein 1; p-MAPK14/p38: phosphorylated mitogen-activated protein kinase 14; RPE: retinal pigment epithelium; RPS6KB/p70 S6 kinase: ribosomal protein S6 kinase; SQSTM1/p62: sequestosome 1; TP53/TRP53/p53: tumor related protein 53; TSC2: TSC complex subunit 2; WT: wild type
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Affiliation(s)
- Kirstan A Vessey
- Department of Anatomy and Physiology, The University of Melbourne, Level 5, Medical Building, Grattan St, Parkville, Victoria, Australia, 3010
| | - Andrew I Jobling
- Department of Anatomy and Physiology, The University of Melbourne, Level 5, Medical Building, Grattan St, Parkville, Victoria, Australia, 3010
| | - Mai X Tran
- Department of Anatomy and Physiology, The University of Melbourne, Level 5, Medical Building, Grattan St, Parkville, Victoria, Australia, 3010
| | - Anna Y Wang
- Department of Anatomy and Physiology, The University of Melbourne, Level 5, Medical Building, Grattan St, Parkville, Victoria, Australia, 3010
| | - Ursula Greferath
- Department of Anatomy and Physiology, The University of Melbourne, Level 5, Medical Building, Grattan St, Parkville, Victoria, Australia, 3010
| | - Erica L Fletcher
- Department of Anatomy and Physiology, The University of Melbourne, Level 5, Medical Building, Grattan St, Parkville, Victoria, Australia, 3010
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Brandli A, Khong FL, Kong RCK, Kelly DJ, Fletcher EL. Transcriptomic analysis of choroidal neovascularization reveals dysregulation of immune and fibrosis pathways that are attenuated by a novel anti-fibrotic treatment. Sci Rep 2022; 12:859. [PMID: 35039609 PMCID: PMC8764037 DOI: 10.1038/s41598-022-04845-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/15/2021] [Indexed: 02/05/2023] Open
Abstract
Neovascular AMD (nAMD) leads to vision loss and is a leading cause of visual impairment in the industrialised world. Current treatments that target blood vessel growth have not been able to treat subretinal fibrosis and nAMD patients continue to lose vision. The molecular mechanisms involved in the development of fibrotic lesions in nAMD are not well understood. The aim of this study was to further understand subretinal fibrosis in the laser photocoagulation model of choroidal neovascularization (CNV) by studying the whole transcriptome of the RPE/choroid following CNV and the application of an anti-fibrotic following CNV. Seven days after laser induced CNV, RPE and choroid tissue was separated and underwent RNAseq. Differential expression analysis and pathway analysis revealed an over representation of immune signalling and fibrotic associated pathways in CNV compared to control RPE/choroid tissue. Comparisons between the mouse CNV model to human CNV revealed an overlap in upregulated expression for immune genes (Ccl2, Ccl8 and Cxcl9) and extracellular matrix remodeling genes (Comp, Lrcc15, Fndc1 and Thbs2). Comparisons between the CNV model and other fibrosis models showed an overlap of over 60% of genes upregulated in either lung or kidney mouse models of fibrosis. Treatment of CNV using a novel cinnamoyl anthranilate anti-fibrotic (OCX063) in the laser induced CNV model was selected as this class of drugs have previously been shown to target fibrosis. CNV lesion leakage and fibrosis was found to be reduced using OCX063 and gene expression of genes within the TGF-beta signalling pathway. Our findings show the presence of fibrosis gene expression pathways present in the laser induced CNV mouse model and that anti-fibrotic treatments offer the potential to reduce subretinal fibrosis in AMD.
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Affiliation(s)
- Alice Brandli
- Department of Anatomy and Physiology, The University of Melbourne, Grattan St, Parkville, VIC, 3010, Australia
| | - Fay L Khong
- Department of Medicine, The University of Melbourne, St Vincent's Hospital, Fitzroy, VIC, 3065, Australia
- Occurx Pty Ltd, 31 Queen St, Melbourne, VIC, 3000, Australia
| | - Roy C K Kong
- Department of Medicine, The University of Melbourne, St Vincent's Hospital, Fitzroy, VIC, 3065, Australia
- Occurx Pty Ltd, 31 Queen St, Melbourne, VIC, 3000, Australia
| | - Darren J Kelly
- Department of Medicine, The University of Melbourne, St Vincent's Hospital, Fitzroy, VIC, 3065, Australia
| | - Erica L Fletcher
- Department of Anatomy and Physiology, The University of Melbourne, Grattan St, Parkville, VIC, 3010, Australia.
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Farashi S, Ansell BR, Wu Z, Abbott CJ, Pébay A, Fletcher EL, Guymer RH, Bahlo M. Genetics of reticular pseudodrusen in age-related macular degeneration. Trends Genet 2022; 38:312-316. [DOI: 10.1016/j.tig.2022.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 12/20/2021] [Accepted: 01/05/2022] [Indexed: 10/19/2022]
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Wu Z, Fletcher EL, Kumar H, Greferath U, Guymer RH. Reticular pseudodrusen: A critical phenotype in age-related macular degeneration. Prog Retin Eye Res 2021; 88:101017. [PMID: 34752916 DOI: 10.1016/j.preteyeres.2021.101017] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Revised: 10/07/2021] [Accepted: 10/29/2021] [Indexed: 12/18/2022]
Abstract
Reticular pseudodrusen (RPD), or subretinal drusenoid deposits (SDD), refer to distinct lesions that occur in the subretinal space. Over the past three decades, their presence in association with age-related macular degeneration (AMD) has become increasingly recognized, especially as RPD have become more easily distinguished with newer clinical imaging modalities. There is also an increasing appreciation that RPD appear to be a critical AMD phenotype, where understanding their pathogenesis will provide further insights into the processes driving vision loss in AMD. However, key barriers to understanding the current evidence related to the independent impact of RPD include the heterogeneity in defining their presence, and failure to account for the confounding impact of the concurrent presence and severity of AMD pathology. This review thus critically discusses the current evidence on the prevalence and clinical significance of RPD and proposes a clinical imaging definition of RPD that will help move the field forward in gathering further key knowledge about this critical phenotype. It also proposes a putative mechanism for RPD formation and how they may drive progression to vision loss in AMD, through examining current evidence and presenting novel findings from preclinical and clinical studies.
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Affiliation(s)
- Zhichao Wu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Erica L Fletcher
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Himeesh Kumar
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia
| | - Ursula Greferath
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Robyn H Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia; Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Australia.
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Dixon MA, Greferath U, Fletcher EL, Jobling AI. The Contribution of Microglia to the Development and Maturation of the Visual System. Front Cell Neurosci 2021; 15:659843. [PMID: 33967697 PMCID: PMC8102829 DOI: 10.3389/fncel.2021.659843] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/29/2021] [Indexed: 12/20/2022] Open
Abstract
Microglia, the resident immune cells of the central nervous system (CNS), were once considered quiescent cells that sat in readiness for reacting to disease and injury. Over the last decade, however, it has become clear that microglia play essential roles in maintaining the normal nervous system. The retina is an easily accessible part of the central nervous system and therefore much has been learned about the function of microglia from studies in the retina and visual system. Anatomically, microglia have processes that contact all synapses within the retina, as well as blood vessels in the major vascular plexuses. Microglia contribute to development of the visual system by contributing to neurogenesis, maturation of cone photoreceptors, as well as refining synaptic contacts. They can respond to neural signals and in turn release a range of cytokines and neurotrophic factors that have downstream consequences on neural function. Moreover, in light of their extensive contact with blood vessels, they are also essential for regulation of vascular development and integrity. This review article summarizes what we have learned about the role of microglia in maintaining the normal visual system and how this has helped in understanding their role in the central nervous system more broadly.
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Affiliation(s)
- Michael A Dixon
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Ursula Greferath
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Erica L Fletcher
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
| | - Andrew I Jobling
- Department of Anatomy and Physiology, The University of Melbourne, Melbourne, VIC, Australia
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Kalloniatis M, Fletcher EL. Retinal degeneration: challenge and opportunity. Clin Exp Optom 2021; 88:265-6. [PMID: 16255684 DOI: 10.1111/j.1444-0938.2005.tb06709.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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14
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Affiliation(s)
- Timothy R. Golding
- Corneal Biophysics Laboratory, Department of Optometry, University of Melbourne
| | - Adrian S. Bruce
- Corneal Biophysics Laboratory, Department of Optometry, University of Melbourne
| | - Erica L. Fletcher
- Corneal Biophysics Laboratory, Department of Optometry, University of Melbourne
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Fletcher EL, Phipps JA, Wilkinson-Berka JL. Dysfunction of retinal neurons and glia during diabetes. Clin Exp Optom 2021; 88:132-45. [PMID: 15926876 DOI: 10.1111/j.1444-0938.2005.tb06686.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2004] [Revised: 04/15/2005] [Accepted: 04/23/2005] [Indexed: 12/27/2022] Open
Abstract
Diabetic retinopathy is the leading cause of blindness in those of working age. It is well known that the retinal vasculature is altered during diabetes. More recently, it has emerged that neuronal and glial dysfunction occurs in those with diabetes. Current research is directed at understanding these neuronal and glial changes because they may be an early manifestation of disease processes that ultimately lead to vascular abnormality. This review will highlight the recent advances in our understanding of the neuronal and glial changes that occur during diabetes.
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Affiliation(s)
- Erica L Fletcher
- Department of Anatomy and Cell Biology, The University of Melbourne, Grattan Street, Parkville, VIC 3010, Australia
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16
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Kalloniatis M, Loh CS, Acosta ML, Tomisich G, Zhu Y, Nivison‐smith L, Fletcher EL, Chua J, Sun D, Arunthavasothy N. Retinal amino acid neurochemistry in health and disease. Clin Exp Optom 2021; 96:310-32. [DOI: 10.1111/cxo.12015] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Revised: 07/01/2012] [Accepted: 07/17/2012] [Indexed: 12/25/2022] Open
Affiliation(s)
- Michael Kalloniatis
- Centre for Eye Health, University of New South Wales, Sydney, New South Wales, Australia,
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia,
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia,
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| | - Chee Seang Loh
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| | - Monica L Acosta
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| | - Guido Tomisich
- Department of Optometry and Vision Science, The University of Melbourne, Parkville, Victoria, Australia,
| | - Yuan Zhu
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia,
| | - Lisa Nivison‐smith
- School of Optometry and Vision Science, University of New South Wales, Sydney, New South Wales, Australia,
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia,
| | - Jacqueline Chua
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| | - Daniel Sun
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
| | - Niru Arunthavasothy
- Department of Optometry and Vision Sciences, New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand,
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17
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Gu BJ, Huang X, Avula PK, Caruso E, Drysdale C, Vessey KA, Ou A, Fowler C, Liu TH, Lin Y, Horton A, Masters CL, Wiley JS, Guymer RH, Fletcher EL. Deficits in Monocyte Function in Age Related Macular Degeneration: A Novel Systemic Change Associated With the Disease. Front Med (Lausanne) 2021; 8:634177. [PMID: 33816525 PMCID: PMC8010137 DOI: 10.3389/fmed.2021.634177] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 02/24/2021] [Indexed: 12/25/2022] Open
Abstract
Age-related macular degeneration (AMD) is characterized by the accumulation of debris in the posterior eye. In this study we evaluated peripheral blood monocyte phagocytic function at various stages of AMD and in aged matched control participants. Real-time tri-color flow cytometry was used to quantify phagocytic function of peripheral blood monocyte subsets (non-classic, intermediate and classic) isolated from subjects with intermediate or late AMD and compared with age matched healthy controls. Assessment of phagocytic function of monocytes isolated from those with and without reticular pseudodrusen was also made, and the effect of glatiramer acetate on phagocytic function assessed. Phagocytic function was reduced in all subjects with AMD, irrespective of stage of disease. However, there was no correlation between phagocytic function and drusen load, nor any difference between the level of phagocytosis in those with or without reticular pseudodrusen. Treatment with glatiramer acetate increased phagocytosis of classical and non-classical monocytes, normalizing the reduction in phagocytosis observed in those with AMD. These findings suggest that defective systemic phagocytosis is associated with both intermediate and late stages of AMD, highlighting a potential role in the accumulation of debris that occurs early in the disease process. Assessing peripheral monocyte phagocytic function provides further insights into the etiology of this disease and offer a novel therapeutic target.
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Affiliation(s)
- Ben J Gu
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia.,National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Xin Huang
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Pavan K Avula
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Emily Caruso
- Department of Surgery (Ophthalmology), Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, VIC, Australia
| | - Candace Drysdale
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia
| | - Amber Ou
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Christopher Fowler
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Tian-Hua Liu
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Yong Lin
- National Clinical Research Center for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, China
| | - Adam Horton
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Colin L Masters
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - James S Wiley
- The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - Robyn H Guymer
- Department of Surgery (Ophthalmology), Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, East Melbourne, VIC, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia
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18
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Lidgerwood GE, Senabouth A, Smith-Anttila CJA, Gnanasambandapillai V, Kaczorowski DC, Amann-Zalcenstein D, Fletcher EL, Naik SH, Hewitt AW, Powell JE, Pébay A. Transcriptomic Profiling of Human Pluripotent Stem Cell-derived Retinal Pigment Epithelium over Time. Genomics Proteomics Bioinformatics 2020; 19:223-242. [PMID: 33307245 PMCID: PMC8602392 DOI: 10.1016/j.gpb.2020.08.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 07/04/2020] [Accepted: 08/12/2020] [Indexed: 12/12/2022]
Abstract
Human pluripotent stem cell (hPSC)-derived progenies are immature versions of cells, presenting a potential limitation to the accurate modelling of diseases associated with maturity or age. Hence, it is important to characterise how closely cells used in culture resemble their native counterparts. In order to select appropriate time points of retinal pigment epithelium (RPE) cultures that reflect native counterparts, we characterised the transcriptomic profiles of the hPSC-derived RPE cells from 1- and 12-month cultures. We differentiated the human embryonic stem cell line H9 into RPE cells, performed single-cell RNA-sequencing of a total of 16,576 cells to assess the molecular changes of the RPE cells across these two culture time points. Our results indicate the stability of the RPE transcriptomic signature, with no evidence of an epithelial–mesenchymal transition, and with the maturing populations of the RPE observed with time in culture. Assessment of Gene Ontology pathways revealed that as the cultures age, RPE cells upregulate expression of genes involved in metal binding and antioxidant functions. This might reflect an increased ability to handle oxidative stress as cells mature. Comparison with native human RPE data confirms a maturing transcriptional profile of RPE cells in culture. These results suggest that long-term in vitro culture of RPE cells allows the modelling of specific phenotypes observed in native mature tissues. Our work highlights the transcriptional landscape of hPSC-derived RPE cells as they age in culture, which provides a reference for native and patient samples to be benchmarked against.
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Affiliation(s)
- Grace E Lidgerwood
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC 3010, Australia; Department of Surgery, The University of Melbourne, Parkville, VIC 3010, Australia; Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC 3002, Australia.
| | - Anne Senabouth
- Garvan Weizmann Centre for Cellular Genomics, Garvan Institute of Medical Research, The Kinghorn Cancer Centre, Darlinghurst, NSW 2010, Australia
| | - Casey J A Smith-Anttila
- Single Cell Open Research Endeavour, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Vikkitharan Gnanasambandapillai
- Garvan Weizmann Centre for Cellular Genomics, Garvan Institute of Medical Research, The Kinghorn Cancer Centre, Darlinghurst, NSW 2010, Australia
| | - Dominik C Kaczorowski
- Garvan Weizmann Centre for Cellular Genomics, Garvan Institute of Medical Research, The Kinghorn Cancer Centre, Darlinghurst, NSW 2010, Australia
| | - Daniela Amann-Zalcenstein
- Single Cell Open Research Endeavour, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Shalin H Naik
- Single Cell Open Research Endeavour, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Immunology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Alex W Hewitt
- Department of Surgery, The University of Melbourne, Parkville, VIC 3010, Australia; Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC 3002, Australia; School of Medicine, Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS 7005, Australia
| | - Joseph E Powell
- Garvan Weizmann Centre for Cellular Genomics, Garvan Institute of Medical Research, The Kinghorn Cancer Centre, Darlinghurst, NSW 2010, Australia; UNSW Cellular Genomics Futures Institute, School of Medical Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Alice Pébay
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC 3010, Australia; Department of Surgery, The University of Melbourne, Parkville, VIC 3010, Australia; Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, VIC 3002, Australia.
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19
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Kakavand K, Jobling AI, Greferath U, Vessey KA, de Iongh RU, Fletcher EL. Photoreceptor Degeneration in Pro23His Transgenic Rats (Line 3) Involves Autophagic and Necroptotic Mechanisms. Front Neurosci 2020; 14:581579. [PMID: 33224023 PMCID: PMC7670078 DOI: 10.3389/fnins.2020.581579] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 10/02/2020] [Indexed: 01/09/2023] Open
Abstract
Photoreceptor death contributes to 50% of irreversible vision loss in the western world. Pro23His (P23H) transgenic albino rat strains are widely used models for the most common rhodopsin gene mutation associated with the autosomal dominant form of retinitis pigmentosa. However, the mechanism(s) by which photoreceptor death occurs are not well understood and were the principal aim of this study. We first used electroretinogram recording and optical coherence tomography to confirm the time course of functional and structural loss. Electroretinogram analyses revealed significantly decreased rod photoreceptor (a-wave), bipolar cell (b-wave) and amacrine cell responses (oscillatory potentials) from P30 onward. The cone-mediated b-wave was also decreased from P30. TUNEL analysis showed extensive cell death at P18, with continued labeling detected until P30. Focused gene expression arrays indicated activation of, apoptosis, autophagy and necroptosis in whole retina from P14-18. However, analysis of mitochondrial permeability changes (ΔΨm) using JC-1 dye, combined with immunofluorescence markers for caspase-dependent (cleaved caspase-3) and caspase-independent (AIF) cell death pathways, indicated mitochondrial-mediated cell death was not a major contributor to photoreceptor death. By contrast, reverse-phase protein array data combined with RIPK3 and phospho-MLKL immunofluorescence indicated widespread necroptosis as the predominant mechanism of photoreceptor death. These findings highlight the complexity of mechanisms involved in photoreceptor death in the Pro23His rat model of degeneration and suggest therapies that target necroptosis should be considered for their potential to reduce photoreceptor death.
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Affiliation(s)
- Kiana Kakavand
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Andrew I Jobling
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Ursula Greferath
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Kirstan A Vessey
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Robb U de Iongh
- Ocular Development Laboratory, Department Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
| | - Erica L Fletcher
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia
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20
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Fletcher EL. Advances in understanding the mechanisms of retinal degenerations. Clin Exp Optom 2020; 103:723-732. [PMID: 33090561 DOI: 10.1111/cxo.13146] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Revised: 08/21/2020] [Accepted: 08/23/2020] [Indexed: 01/13/2023] Open
Abstract
Photoreceptor death is an important contributor to irreversible vision loss worldwide. In this review, I outline our work examining the role that purines, such as adenosine triphosphate (ATP), have in normal retinal function and in retinal disease. Our work shows that the actions of ATP, mediated by P2X receptors, are expressed in various retinal layers including photoreceptor terminals, and when stimulated by excessive levels of ATP is associated with rapid death of neurons. Treatment with a compound that blocks the action of P2X and some P2Y receptors reduces photoreceptor death in a mouse model of retinal degeneration. Our observations not only provide a means for developing a potential treatment for reducing photoreceptor death, but also provides a novel way of studying the neural plasticity effects that develop in the inner retina following photoreceptor death. There are a range of inner retinal changes that could influence the effectiveness of retinal prostheses. Indeed, using an ATP-induced degeneration model, we established that the amount of electrical stimulation required to elicit a response in the visual cortex was affected by the level of glial scarring. However, changes in P2X7 receptor expression by OFF ganglion cells during retinal degeneration can also be exploited by photoswitches to restore light sensitivity to degenerated retinae. Finally, our work has also considered how P2X7 expression by innate immune cells, and its role as a scavenger receptor, contributes to age-related macular degeneration (AMD). Our results show that loss of P2X7 function is associated with thickening of Bruch's membrane as well as increased risk of advanced disease in people with AMD. Overall, our work over the last 20 years highlights the importance of purinergic signalling in normal retinal function and retinal disease and suggest that developing therapies that target P2X7 function could be of benefit for these diseases.
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Affiliation(s)
- Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
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21
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Fletcher EL. Contribution of microglia and monocytes to the development and progression of age related macular degeneration. Ophthalmic Physiol Opt 2020; 40:128-139. [PMID: 32017190 DOI: 10.1111/opo.12671] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 12/10/2019] [Accepted: 01/03/2020] [Indexed: 12/12/2022]
Abstract
PURPOSE Age related macular degeneration (AMD) is the leading cause of irreversible vision loss in industrialised nations. Based on genetics, as well as proteome analysis of drusen, the role the innate immune system in the development and/or progression of the disease is well established. Mononuclear phagocytes, such as microglia and monocytes, play critical roles in innate immunity. Here, the role of retinal microglia in mediating normal retinal function, and how these cells change with age is discussed, so as to understand their role in the development and progression of AMD. RECENT FINDINGS It is now known that microglia dynamically survey the neural environment, responding rapidly to even the most subtle neural injury. The dynamic and phagocytic roles of microglia can change with age contributing to alteration in the response of these cells to damage with age. Accumulation of innate immune cells in the subretinal space is a hallmark feature of the development of AMD, reflecting either an increase in migration of monocytes into the retina, or a failure of immune cell elimination from the retina. Furthermore, changes in phagocytic ability of immune cells could contribute to the accumulation of drusen deposits in the posterior eye. SUMMARY An overview of how retinal microglia maintain retinal homeostasis under normal conditions is provided, and then how they contribute to each stage of AMD. In addition, circulating monocytes are altered in those with AMD, contributing to the overall inflammatory state. Understanding the role of cells of the innate immune system in AMD may uncover novel therapeutic targets with which to reduce either the development or progression of disease.
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Affiliation(s)
- Erica L Fletcher
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia
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22
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Zhao D, Wong VHY, Nguyen CTO, Jobling AI, Fletcher EL, Vingrys AJ, Bui BV. Reversibility of Retinal Ganglion Cell Dysfunction From Chronic IOP Elevation. Invest Ophthalmol Vis Sci 2020; 60:3878-3886. [PMID: 31529082 DOI: 10.1167/iovs.19-27113] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To test the hypothesis that the capacity for retinal ganglion cells to functionally recover from chronic IOP elevation is dependent on the duration of IOP elevation. Methods IOP elevation was induced in one eye in anesthetized (isoflurane) adult C57BL6/J mice using a circumlimbal suture. Sutures were left in place for 8 and 16 weeks (n = 30 and 28). In two other groups the suture was cut after 8 and 12 weeks (n = 30 and 28), and ganglion cell function (electroretinography) and retinal structure (optical coherence tomography) were assessed 4 weeks later. Ganglion cell density was quantified by counting RBPMS (RNA-binding protein with multiple splicing)-stained cells. Results With IOP elevation (∼10 mm Hg above baseline), ganglion cell function declined to 75% ± 8% at 8 weeks and 59% ± 4% at 16 weeks relative to contralateral control eyes. The retinal nerve fiber layer was thinner at 8 (84% ± 4%) and 16 weeks (83% ± 3%), without a significant difference in total retinal thickness. Ganglion cell function recovered with IOP normalization (suture removal) at week 8 (97% ± 7%), but not at week 12 (73% ± 6%). Ganglion cell loss was found in all groups (-8% to -13%). Conclusions In the mouse circumlimbal suture model, 12 weeks of IOP elevation resulted in irreversible ganglion cell dysfunction, whereas retinal dysfunction was fully reversible after 8 weeks of IOP elevation.
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Affiliation(s)
- Da Zhao
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Christine T O Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Victoria, Australia
| | - Algis J Vingrys
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
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23
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Wang AY, Lee PY, Bui BV, Jobling AI, Greferath U, Brandli A, Dixon MA, Findlay Q, Fletcher EL, Vessey KA. Potential mechanisms of retinal ganglion cell type-specific vulnerability in glaucoma. Clin Exp Optom 2019; 103:562-571. [PMID: 31838755 DOI: 10.1111/cxo.13031] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 10/17/2019] [Accepted: 11/16/2019] [Indexed: 12/22/2022] Open
Abstract
Glaucoma is a neurodegenerative disease characterised by progressive damage to the retinal ganglion cells (RGCs), the output neurons of the retina. RGCs are a heterogenous class of retinal neurons which can be classified into multiple types based on morphological, functional and genetic characteristics. This review examines the body of evidence supporting type-specific vulnerability of RGCs in glaucoma and explores potential mechanisms by which this might come about. Studies of donor tissue from glaucoma patients have generally noted greater vulnerability of larger RGC types. Models of glaucoma induced in primates, cats and mice also show selective effects on RGC types - particularly OFF RGCs. Several mechanisms may contribute to type-specific vulnerability, including differences in the expression of calcium-permeable receptors (for example pannexin-1, P2X7, AMPA and transient receptor potential vanilloid receptors), the relative proximity of RGCs and their dendrites to blood supply in the inner plexiform layer, as well as differing metabolic requirements of RGC types. Such differences may make certain RGCs more sensitive to intraocular pressure elevation and its associated biomechanical and vascular stress. A greater understanding of selective RGC vulnerability and its underlying causes will likely reveal a rich area of investigation for potential treatment targets.
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Affiliation(s)
- Anna Ym Wang
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Pei Ying Lee
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, The University of Melbourne, Melbourne, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Alice Brandli
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Michael A Dixon
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Quan Findlay
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Australia
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24
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Phipps JA, Dixon MA, Jobling AI, Wang AY, Greferath U, Vessey KA, Fletcher EL. The renin-angiotensin system and the retinal neurovascular unit: A role in vascular regulation and disease. Exp Eye Res 2019; 187:107753. [PMID: 31408629 DOI: 10.1016/j.exer.2019.107753] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/31/2019] [Accepted: 08/05/2019] [Indexed: 01/16/2023]
Abstract
The retina is known to have a local renin-angiotensin system (RAS) and dysfunction in the RAS is often associated with diseases of the retinal vasculature that cause irreversible vision loss. Regulation of the retinal vasculature to meet the metabolic needs of the tissues occurs through a mechanism called neurovascular coupling, which is critical for maintaining homeostatic function and support for neurons. Neurovascular coupling is the process by which support cells, including glia, regulate blood vessel calibre and blood flow in response to neural activity. In retinal vascular diseases, this coupling mechanism is often disrupted. However, the role that angiotensin II (Ang II), the main effector peptide of the RAS, has in regulating both the retinal vasculature and neurovascular coupling is not fully understood. As components of the RAS are located on the principal neurons, glia and blood vessels of the retina, it is possible that Ang II has a role in regulating communication and function between these three cell types, and therefore the capacity to regulate neurovascular coupling. This review focuses on components of the RAS located on the retinal neurovascular unit, and the potential of this system to contribute to blood flow modulation in the healthy and compromised retina.
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Affiliation(s)
- Joanna A Phipps
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Michael A Dixon
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Anna Y Wang
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, Victoria, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, Victoria, Australia.
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25
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Guymer RH, Wu Z, Hodgson LA, Caruso E, Brassington KH, Tindill N, Aung KZ, McGuinness MB, Fletcher EL, Chen FK, Chakravarthy U, Arnold JJ, Heriot WJ, Durkin SR, Lek JJ, Harper CA, Wickremasinghe SS, Sandhu SS, Baglin EK, Sharangan P, Braat S, Luu CD. Subthreshold Nanosecond Laser Intervention in Age-Related Macular Degeneration. Ophthalmology 2019; 126:829-838. [DOI: 10.1016/j.ophtha.2018.09.015] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 09/11/2018] [Accepted: 09/11/2018] [Indexed: 01/12/2023] Open
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26
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Fletcher EL, Wang AY, Jobling AI, Rutar MV, Greferath U, Gu B, Vessey KA. Targeting P2X7 receptors as a means for treating retinal disease. Drug Discov Today 2019; 24:1598-1605. [PMID: 30954685 DOI: 10.1016/j.drudis.2019.03.029] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 03/07/2019] [Accepted: 03/29/2019] [Indexed: 12/28/2022]
Abstract
Age-related macular degeneration and glaucoma are the commonest causes of irreversible vision loss in industrialized countries. The purine ATP is known to regulate a range of cellular functions in the retina via its action on P2 receptors, especially the P2X7 receptor. Although agents that attenuate P2X7 receptor function have been in development for many years, no compound is currently approved for the treatment of eye disease. However, newer compounds that cross the blood-brain barrier could have potential to reduce vision loss. This review will outline recent information relating to the role of P2X7 in age-related macular degeneration and glaucoma and, subsequently, we will discuss recent developments for attenuating P2X7 receptor function.
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Affiliation(s)
- Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville 3010, Victoria, Australia.
| | - Anna Y Wang
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville 3010, Victoria, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville 3010, Victoria, Australia
| | - Matthew V Rutar
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville 3010, Victoria, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville 3010, Victoria, Australia
| | - Ben Gu
- Florey Institute of Neuroscience and Mental Health, Parkville 3010, Victoria, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville 3010, Victoria, Australia
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Luu CD, Tan R, Caruso E, Fletcher EL, Lamb TD, Guymer RH. Topographic Rod Recovery Profiles after a Prolonged Dark Adaptation in Subjects with Reticular Pseudodrusen. Ophthalmol Retina 2018; 2:1206-1217. [PMID: 31047193 DOI: 10.1016/j.oret.2018.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 06/14/2018] [Accepted: 06/27/2018] [Indexed: 06/09/2023]
Abstract
PURPOSE Although rod function is known to be severely impaired in eyes with reticular pseudodrusen (RPD), it remains unknown whether this impairment is associated with a total loss of rod function or merely a delay in rod recovery. The purpose of the study was to determine rod functional recovery profiles after prolonged dark adaptation (DA) in eyes with age-related macular degeneration (AMD) and RPD. DESIGN A cross-sectional, case-series study. PARTICIPANTS Subjects with AMD and RPD. METHODS Retinal sensitivity was assessed simultaneously at 14 retinal locations within the central 12° in the study eye of each subject after the eye received approximately 20% bleach. Recovery of retinal sensitivity was monitored at regular intervals up to 30 minutes after bleach. If retinal sensitivity of all test points had not recovered to the rod criterion level (-3.0 log units of stimulus intensity) after 30 minutes of DA, monitoring recovery of retinal sensitivity was extended up to 24 hours of DA. MAIN OUTCOME MEASURES Rod functional recovery profile at each test point. RESULTS Six AMD cases with RPD were included, aged 69 to 79 years, and visual acuity ranged from 20/20 to 20/25. All cases had a delay in rod functional recovery at many retinal locations, with test points within the central 6° most affected. The recovery rate was variable between retinal loci and between subjects, although RPD were present at all test locations. In 5 cases with stage 3 RPD, rod function recovered at all tested locations, but many locations took hours to do so. The case with stage 4 RPD had locations that failed to recover even after 24 hours of DA. CONCLUSIONS Eyes with AMD and RPD are associated with severe rod dysfunction throughout the macula; however, rod function does recover in most cases after an extended DA time. These findings suggest that the delay in rod recovery in eyes with RPD is, in most cases, associated with the impairment rather than the total loss of rod photoreceptor function. Stage 4 RPD may represent a point at which some rod photoreceptors are nonfunctional.
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Affiliation(s)
- Chi D Luu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Department of Surgery (Ophthalmology), The University of Melbourne, East Melbourne, Victoria, Australia.
| | - Rose Tan
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Department of Surgery (Ophthalmology), The University of Melbourne, East Melbourne, Victoria, Australia
| | - Emily Caruso
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Department of Surgery (Ophthalmology), The University of Melbourne, East Melbourne, Victoria, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia
| | - Trevor D Lamb
- Eccles Institute of Neuroscience, John Curtin School of Medical Research, The Australian National University, Canberra, ACT, Australia
| | - Robyn H Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Department of Surgery (Ophthalmology), The University of Melbourne, East Melbourne, Victoria, Australia
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von Eisenhart-Rothe P, Grubman A, Greferath U, Fothergill LJ, Jobling AI, Phipps JA, White AR, Fletcher EL, Vessey KA. Failure of Autophagy–Lysosomal Pathways in Rod Photoreceptors Causes the Early Retinal Degeneration Phenotype Observed inCln6nclfMice. ACTA ACUST UNITED AC 2018; 59:5082-5097. [DOI: 10.1167/iovs.18-24757] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
| | - Alexandra Grubman
- Department of Pathology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Linda J. Fothergill
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Andrew I. Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Joanna A. Phipps
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Anthony R. White
- Department of Pathology, The University of Melbourne, Melbourne, Victoria, Australia
| | - Erica L. Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Kirstan A. Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
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Phipps JA, Vessey KA, Brandli A, Nag N, Tran MX, Jobling AI, Fletcher EL. The Role of Angiotensin II/AT1 Receptor Signaling in Regulating Retinal Microglial Activation. Invest Ophthalmol Vis Sci 2018; 59:487-498. [PMID: 29368003 DOI: 10.1167/iovs.17-22416] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose This study explored whether the proangiogenic factor Angiotensin II (AngII) had a direct effect on the activation state of microglia via the Angiotensin type 1 receptor (AT1-R). Methods Microglial dynamic activity was investigated in live retinal flatmounts from adult Cx3Cr1+/GFP mice under control, AngII (5 μM) or AngII (5 μM) + candesartan (0.227 μM) conditions. The effects of intravitreal administration of AngII (10 mM) were also investigated at 24 hours, with retinae processed for immunocytochemistry, flow cytometry, or inflammatory quantitative PCR arrays. Results We found FACS isolated retinal microglia expressed AT1-R. In retinal flatmounts, microglia showed characteristic movement of processes under control conditions. Perfusion of AngII induced an immediate change in process length (-42%, P < 0.05) and activation state of microglia that was ameliorated by AT1-R blockade, suggesting a direct effect of AngII on microglia via the AT1-R. Intravitreal injection of AngII induced microglial activation after 24 hours, which was characterized by increased soma size (23%, P < 0.001) and decreased process length (20%, P < 0.05). Further analysis indicated a significant decrease in the number of microglial contacts with retinal neurons (saline 15.6 ± 2.31 versus AngII 7.8 ± 1.06, P < 0.05). Retinal cytokine and chemokine expression was modulated, indicative of an inflammatory retinal phenotype. Conclusions We show that retinal microglia express AT1-R and their activation state is significantly altered by the angiogenic factor, AngII. Specifically, AngII may directly activate AT1-Rs on microglia and contribute to retinal inflammation. This may have implications for diseases like diabetic retinopathy where increases in AngII and inflammation have been shown to play an important role.
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Affiliation(s)
- Joanna A Phipps
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Alice Brandli
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Nupur Nag
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Mai X Tran
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
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Findlay Q, Jobling AI, Vessey KA, Greferath U, Phipps JA, Guymer RH, Fletcher EL. Prophylactic laser in age-related macular degeneration: the past, the present and the future. Eye (Lond) 2018; 32:972-980. [PMID: 29520049 PMCID: PMC5944648 DOI: 10.1038/s41433-018-0035-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 01/14/2018] [Indexed: 11/09/2022] Open
Abstract
The presence of drusen in the posterior eye is a hallmark feature of the early stages of age-related macular degeneration and their size is an indicator of risk of progression to vision-threatening forms of the disease. Since the initial observations that laser treatment can resolve drusen, there has been great interest in whether laser treatment can be used to reduce the progression of age-related macular degeneration. In this article, we review the development of lasers for the treatment of those with age-related macular degeneration. We provide an overview of the clinical trial results that demonstrated drusen resolution but that had mixed effects on progression of disease. In addition, we provide a summary of the recent developments in pulsed lasers that are designed to reduce the energy applied to the posterior eye to provide the therapeutic effects of conventional continuous wave lasers while reducing the secondary tissue effects.
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Affiliation(s)
- Quan Findlay
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, VIC, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, VIC, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, VIC, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, VIC, Australia
| | - Joanna A Phipps
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, VIC, Australia
| | - Robyn H Guymer
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Parkville, VIC, Australia.
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, 3010, VIC, Australia
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Chhablani J, Roh YJ, Jobling AI, Fletcher EL, Lek JJ, Bansal P, Guymer R, Luttrull JK. Restorative retinal laser therapy: Present state and future directions. Surv Ophthalmol 2018; 63:307-328. [DOI: 10.1016/j.survophthal.2017.09.008] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2017] [Revised: 09/13/2017] [Accepted: 09/22/2017] [Indexed: 01/30/2023]
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Vessey KA, Ho T, Jobling AI, Mills SA, Tran MX, Brandli A, Lam J, Guymer RH, Fletcher EL. Nanosecond Laser Treatment for Age-Related Macular Degeneration Does Not Induce Focal Vision Loss or New Vessel Growth in the Retina. ACTA ACUST UNITED AC 2018; 59:731-745. [DOI: 10.1167/iovs.17-23098] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Kirstan A. Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Tracy Ho
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Andrew I. Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Samuel A. Mills
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Mai X. Tran
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Alice Brandli
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Jackson Lam
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Robyn H. Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital; Department of Surgery (Ophthalmology), The University of Melbourne, Victoria, Australia
| | - Erica L. Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
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Abstract
Analysis of how retinal ganglion cells change in retinal degeneration is critical for evaluating the potential of photoreceptor restorative therapies. Immunocytochemistry in combination with image analysis provides a way for quantifying not only the density of ganglion cells during disease, but also information about their morphology and an evaluation of excitatory and inhibitory synaptic inputs. Here, we describe how indirect immunofluorescence can be used in retinal whole mounts to obtain information about ganglion cells in retinal degeneration.
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Affiliation(s)
- Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia.
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia
| | - Susmita Saha
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia
| | - Emily E Anderson
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC, Australia
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Surrao DC, Greferath U, Chau YQ, Skabo SJ, Huynh M, Shelat KJ, Limnios IJ, Fletcher EL, Liu Q. Design, development and characterization of synthetic Bruch's membranes. Acta Biomater 2017; 64:357-376. [PMID: 28951331 DOI: 10.1016/j.actbio.2017.09.032] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 09/13/2017] [Accepted: 09/22/2017] [Indexed: 12/30/2022]
Abstract
Age-related macular degeneration (AMD) is a leading cause of blindness, and dry AMD has no effective treatment. Retinal constructs comprising retinal pigment epithelium (RPE) cells supported by electrospun scaffolds have been investigated to treat dry AMD. However, electrospun scaffolds studied to-date do not mimic the structural microenvironment of human Bruch's membrane (BM), essential for native-like RPE monolayers. The aim of this study was to develop a structurally biomimetic scaffold designed to support a functional RPE monolayer, comprising porous, electrospun nanofibrous membranes (ENMs), coated with laminin, mimicking the inner collagenous layer (ICL) and basal RPE lamina respectively, the cell supporting layers of the BM. In vitro evaluation showed 70nm PLLA ENMs adsorbed high amounts of laminin and supported functional RPE monolayers, exhibiting 3D polygonal-cobblestone morphology, apical microvilli, basal infoldings, high transepithelial resistance (TER), phagocytic activity and expression of signature RPE markers. 70nm PLLA ENMs were successfully implanted into the subretinal space of RCS-rdy+p+/LAV rats, also commonly know as rdy rats. At week 4, in the absence of immunosuppressants, implanted PLLA ENMs were surrounded by a significantly low number of activated microglial cells, compared to week 1, indicating no adverse long-term immune response. In conclusion, we successfully designed and tested ENMs emulating the RPE cell supporting layers of the BM, and found 70nm PLLA ENMs to be best suited as scaffolds for fabricating retinal constructs. STATEMENT OF SIGNIFICANCE Age related macular degeneration (AMD) is a leading cause of vision loss in the developed world, with an increasing number of people suffering from blindness or severe visual impairment. Transplantation of retinal pigment epithelium (RPE) cells supported on a synthetic, biomimetic-like Bruch's membrane (BM) is considered a promising treatment. However, the synthetic scaffolds used do not mimic the microenvironment of the RPE cell supporting layers, required for the development of a functional RPE monolayer. This study indicated that porous, laminin coated, 70nm PLLA ENMs supported functional RPE monolayers, exhibiting 3D polygonal-cobblestone morphology, apical microvilli, basal infoldings, high transepithelial resistance (TER), phagocytic activity and expression of signature RPE markers. These findings indicate the potential clinical use of porous, laminin coated, 70nm PLLA ENMs in fabricating retinal constructs aimed at treating dry AMD.
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Affiliation(s)
- Denver C Surrao
- Clem Jones Research Centre for Regenerative Medicine, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD 4229, Australia.
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Yu-Qian Chau
- Clem Jones Research Centre for Regenerative Medicine, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD 4229, Australia
| | - Stuart J Skabo
- Clem Jones Research Centre for Regenerative Medicine, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD 4229, Australia
| | - Mario Huynh
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Kinnari J Shelat
- Australian Institute for Bioengineering and Nanotechnology (AIBN), The University of Queensland, Brisbane, QLD 4072, Australia; Australian National Fabrication Facility (ANFF), Queensland Node, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Ioannis J Limnios
- Clem Jones Research Centre for Regenerative Medicine, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD 4229, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Qin Liu
- Clem Jones Research Centre for Regenerative Medicine, Faculty of Health Sciences and Medicine, Bond University, Gold Coast, QLD 4229, Australia
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Grubman A, Guennel P, Vessey KA, Jones MWM, James SA, de Jonge MD, White AR, Fletcher EL. X-ray fluorescence microscopic measurement of elemental distribution in the mouse retina with age. Metallomics 2017; 8:1110-1121. [PMID: 27481440 DOI: 10.1039/c6mt00055j] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The biologically important metals such as zinc, copper and iron play key roles in retinal function, yet no study has mapped the spatio-temporal distribution of retinal biometals in healthy or diseased retina. We investigated a natural mouse model of retinal degeneration, the Cln6nclf mouse. As dysfunctional metabolism of biometals is observed in the brains of these animals and deregulated metal homeostasis has been linked to retinal degeneration, we focused on mapping the elemental distribution in the healthy and Cln6nclf mouse retina with age. Retinal and RPE elemental homeostasis was mapped in Cln6nclf and C57BL6/J mice from 1 to 8 months of age using X-ray Fluorescence Microscopy at the Australian Synchrotron. In the healthy retina, we detected a progressive loss of phosphorus in the outer nuclear layer and significant reduction in iron in the inner segments of the photoreceptors. Further investigation revealed a unique elemental signature for each retinal layer, with high areal concentrations of iron and sulfur in the photoreceptor segments and calcium, phosphorus, zinc and potassium enrichment predominantly in the nuclear layers. The analysis of retinae from Cln6nclf mice did not show significant temporal changes in elemental distributions compared to age matched controls, despite significant photoreceptor cell loss. Our data therefore demonstrates that retinal layers have unique elemental composition. Elemental distribution is, with few exceptions, stably maintained over time in healthy and Cln6nclf mouse retina, suggesting conservation of elemental distribution is critical for basic retinal function with age and is not modulated by processes underlying retinal degeneration.
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Affiliation(s)
- Alexandra Grubman
- Department of Pathology, The University of Melbourne, Victoria, Australia
| | - Philipp Guennel
- Department of Anatomy and Neuroscience, The University of Melbourne, Victoria, Australia.
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Victoria, Australia.
| | - Michael W M Jones
- Australian Synchrotron, Clayton, Victoria, Australia and ARC Centre of Excellence for Advanced Molecular Imaging, La Trobe University, Victoria, Australia
| | - Simon A James
- Australian Synchrotron, Clayton, Victoria, Australia and The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia
| | - Martin D de Jonge
- Australian Synchrotron, Clayton, Victoria, Australia and ARC Centre of Excellence for Advanced Molecular Imaging, La Trobe University, Victoria, Australia
| | - Anthony R White
- Department of Pathology, The University of Melbourne, Victoria, Australia and The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Victoria, Australia and A.I. Virtanen Institute for Molecular Sciences, Department of Neurobiology, University of Eastern Finland, Kuopio, Finland
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Victoria, Australia.
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Vessey KA, Gu BJ, Jobling AI, Phipps JA, Greferath U, Tran MX, Dixon MA, Baird PN, Guymer RH, Wiley JS, Fletcher EL. Loss of Function of P2X7 Receptor Scavenger Activity in Aging Mice: A Novel Model for Investigating the Early Pathogenesis of Age-Related Macular Degeneration. Am J Pathol 2017. [PMID: 28628761 DOI: 10.1016/j.ajpath.2017.04.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Age-related macular degeneration (AMD) is a leading cause of irreversible, severe vision loss in Western countries. Recently, we identified a novel pathway involving P2X7 receptor scavenger function expressed on ocular immune cells as a risk factor for advanced AMD. In this study, we investigate the effect of loss of P2X7 receptor function on retinal structure and function during aging. P2X7-null and wild-type C57bl6J mice were investigated at 4, 12, and 18 months of age for macrophage phagocytosis activity, ocular histological changes, and retinal function. Phagocytosis activity of blood-borne macrophages decreased with age at 18 months in the wild-type mouse. Lack of P2X7 receptor function reduced phagocytosis at all ages compared to wild-type mice. At 12 months of age, P2X7-null mice had thickening of Bruchs membrane and retinal pigment epithelium dysfunction. By 18 months of age, P2X7-null mice displayed phenotypic characteristics consistent with early AMD, including Bruchs membrane thickening, retinal pigment epithelium cell loss, retinal functional deficits, and signs of subretinal inflammation. Our present study shows that loss of function of the P2X7 receptor in mice induces retinal changes representing characteristics of early AMD, providing a valuable model for investigating the role of scavenger receptor function and the immune system in the development of this age-related disease.
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Affiliation(s)
- Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Ben J Gu
- Florey Institute of Neuroscience, Melbourne, Victoria, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Joanna A Phipps
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Mai X Tran
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Michael A Dixon
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Paul N Baird
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia; Division of Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Victoria, Australia
| | - Robyn H Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, Melbourne, Victoria, Australia; Division of Ophthalmology, Department of Surgery, The University of Melbourne, Melbourne, Victoria, Australia
| | - James S Wiley
- Florey Institute of Neuroscience, Melbourne, Victoria, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia.
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Aplin FP, Fletcher EL, Luu CD, Vessey KA, Allen PJ, Guymer RH, Shepherd RK, Shivdasani MN. Stimulation of a Suprachoroidal Retinal Prosthesis Drives Cortical Responses in a Feline Model of Retinal Degeneration. Invest Ophthalmol Vis Sci 2017; 57:5216-5229. [PMID: 27701633 DOI: 10.1167/iovs.16-19926] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose Retinal prostheses have emerged as a promising technology to restore vision in patients with severe photoreceptor degeneration. To better understand how neural degeneration affects the efficacy of electronic implants, we investigated the function of a suprachoroidal retinal implant in a feline model. Methods Unilateral retinal degeneration was induced in four adult felines by intravitreal injection of adenosine triphosphate (ATP). Twelve weeks post injection, animals received suprachoroidal electrode array implants in each eye, and responses to electrical stimulation were obtained using multiunit recordings from the visual cortex. Histologic measurements of neural and glial changes in the retina at the implant site were correlated with cortical thresholds from individual stimulating electrodes. Results Adenosine triphosphate-injected eyes displayed changes consistent with mid-to-late stage retinal degeneration and remodeling. A significant increase in electrical charge was required to induce a cortical response from stimulation of the degenerated retina compared to that in the fellow control eye. Spatial and temporal characteristics of the electrically evoked cortical responses were no different between eyes. Individual electrode thresholds varied in both the control and the ATP-injected eyes and were correlated with ganglion cell density. In ATP-injected eyes, cortical threshold was also independently correlated with an increase in the extent of retinal gliosis. Conclusions These data suggest that even when ganglion cell density remains unaffected, glial changes in the retina following degeneration can influence the efficacy of suprachoroidal electrical stimulation. A better understanding of how glial change impacts retinal prosthesis function may help to further the optimization of retinal implants.
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Affiliation(s)
- Felix P Aplin
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia 2Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia 3The Bionics Institute, East Melbourne, Victoria, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Chi D Luu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia 4Department of Surgery (Ophthalmology), The University of Melbourne, Parkville, Victoria, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, Victoria, Australia
| | - Penelope J Allen
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
| | - Robyn H Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia 4Department of Surgery (Ophthalmology), The University of Melbourne, Parkville, Victoria, Australia
| | - Robert K Shepherd
- The Bionics Institute, East Melbourne, Victoria, Australia 5Medical Bionics Department, The University of Melbourne, Melbourne, Victoria, Australia
| | - Mohit N Shivdasani
- The Bionics Institute, East Melbourne, Victoria, Australia 5Medical Bionics Department, The University of Melbourne, Melbourne, Victoria, Australia
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Zhao D, Nguyen CTO, Wong VHY, Lim JKH, He Z, Jobling AI, Fletcher EL, Chinnery HR, Vingrys AJ, Bui BV. Characterization of the Circumlimbal Suture Model of Chronic IOP Elevation in Mice and Assessment of Changes in Gene Expression of Stretch Sensitive Channels. Front Neurosci 2017; 11:41. [PMID: 28239332 PMCID: PMC5301305 DOI: 10.3389/fnins.2017.00041] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 01/19/2017] [Indexed: 12/30/2022] Open
Abstract
To consider whether a circumlimbal suture can be used to chronically elevate intraocular pressure (IOP) in mice and to assess its effect on retinal structure, function and gene expression of stretch sensitive channels. Anesthetized adult C57BL6/J mice had a circumlimbal suture (10/0) applied around the equator of one eye. In treated eyes (n = 23) the suture was left in place for 12 weeks whilst in sham control eyes the suture was removed at day two (n = 17). Contralateral eyes served as untreated controls. IOP was measured after surgery and once a week thereafter. After 12 weeks, electroretinography (ERG) was performed to assess photoreceptor, bipolar cell and retinal ganglion cell (RGC) function. Retinal structure was evaluated using optical coherence tomography. Retinae were processed for counts of ganglion cell density or for quantitative RT-PCR to quantify purinergic (P2x7, Adora3, Entpd1) or stretch sensitive channel (Panx1, Trpv4) gene expression. Immediately after suture application, IOP spiked to 33 ± 3 mmHg. After 1 day, IOP had recovered to 27 ± 3 mmHg. Between weeks 2 and 12, IOP remained elevated above baseline (control 14 ± 1 mmHg, ocular hypertensive 19 ± 1 mmHg). Suture removal at day 2 (Sham) restored IOP to baseline levels, where it remained through to week 12. ERG analysis showed that 12 weeks of IOP elevation reduced photoreceptor (−15 ± 4%), bipolar cell (−15 ± 4%) and ganglion cell responses (−19 ± 6%) compared to sham controls and respective contralateral eyes (untreated). The retinal nerve fiber layer was thinned in the presence of normal total retinal thickness. Ganglion cell density was reduced across all quadrants (superior −12 ± 5%; temporal, −7% ± 2%; inferior −9 ± 4%; nasal −8 ± 5%). Quantitative RT-PCR revealed a significant increase in Entpd1 gene expression (+11 ± 4%), whilst other genes were not significantly altered (P2x7, Adora3, Trpv4, Panx1). Our results show that circumlimbal ligation produces mild chronic ocular hypertension and retinal dysfunction in mice. Consistent with a sustained change to purinergic signaling we found an up-regulation of Entpd1.
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Affiliation(s)
- Da Zhao
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Christine T O Nguyen
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Vickie H Y Wong
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Jeremiah K H Lim
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Zheng He
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, University of Melbourne Parkville, VIC, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, University of Melbourne Parkville, VIC, Australia
| | - Holly R Chinnery
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Algis J Vingrys
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
| | - Bang V Bui
- Department of Optometry and Vision Sciences, University of Melbourne Parkville, VIC, Australia
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Ahnood A, Meffin H, Garrett DJ, Fox K, Ganesan K, Stacey A, Apollo NV, Wong YT, Lichter SG, Kentler W, Kavehei O, Greferath U, Vessey KA, Ibbotson MR, Fletcher EL, Burkitt AN, Prawer S. Diamond Devices for High Acuity Prosthetic Vision. ACTA ACUST UNITED AC 2016; 1:e1600003. [DOI: 10.1002/adbi.201600003] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Revised: 10/27/2016] [Indexed: 12/17/2022]
Affiliation(s)
- Arman Ahnood
- School of Physics University of Melbourne Victoria 3010 Australia
| | - Hamish Meffin
- National Vision Research Institute Australian College of Optometry Victoria 3053 Australia
- ARC Centre of Excellence for Integrative Brain Function Department of Optometry and Vision Science University of Melbourne Victoria 3010 Australia
| | - David J. Garrett
- School of Physics University of Melbourne Victoria 3010 Australia
| | - Kate Fox
- School of Physics University of Melbourne Victoria 3010 Australia
- School of Engineering RMIT University Melbourne 3000 Australia
| | | | - Alastair Stacey
- School of Physics University of Melbourne Victoria 3010 Australia
| | | | - Yan T. Wong
- National Vision Research Institute Australian College of Optometry Victoria 3053 Australia
- Department of Electrical & Electronic Engineering The University of Melbourne Victoria 3010 Australia
| | | | - William Kentler
- Department of Electrical & Electronic Engineering The University of Melbourne Victoria 3010 Australia
| | - Omid Kavehei
- School of Engineering RMIT University Melbourne 3000 Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience University of Melbourne Victoria 3010 Australia
| | - Kirstan A. Vessey
- Department of Anatomy and Neuroscience University of Melbourne Victoria 3010 Australia
| | - Michael R. Ibbotson
- National Vision Research Institute Australian College of Optometry Victoria 3053 Australia
- ARC Centre of Excellence for Integrative Brain Function Department of Optometry and Vision Science University of Melbourne Victoria 3010 Australia
| | - Erica L. Fletcher
- Department of Anatomy and Neuroscience University of Melbourne Victoria 3010 Australia
| | - Anthony N. Burkitt
- Department of Electrical & Electronic Engineering The University of Melbourne Victoria 3010 Australia
| | - Steven Prawer
- School of Physics University of Melbourne Victoria 3010 Australia
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Ho T, Aplin FP, Jobling AI, Phipps JA, de Iongh RU, Greferath U, Vessey KA, Fletcher EL. Localization and Possible Function of P2X Receptors in Normal and Diseased Retinae. J Ocul Pharmacol Ther 2016; 32:509-517. [DOI: 10.1089/jop.2015.0158] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Tracy Ho
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Felix P. Aplin
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Andrew I. Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Joanna A. Phipps
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Robb U. de Iongh
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Kirstan A. Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
| | - Erica L. Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, Australia
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Gu BJ, Huang X, Ou A, Rembach A, Fowler C, Avula PK, Horton A, Doecke JD, Villemagne VL, Macaulay SL, Maruff P, Fletcher EL, Guymer R, Wiley JS, Masters CL. Innate phagocytosis by peripheral blood monocytes is altered in Alzheimer's disease. Acta Neuropathol 2016; 132:377-89. [PMID: 27411339 DOI: 10.1007/s00401-016-1596-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Revised: 06/27/2016] [Accepted: 07/05/2016] [Indexed: 11/30/2022]
Abstract
Sporadic Alzheimer's disease (AD) is characterised by the deposition and accumulation of specific protein aggregates. Failure of clearance could underlie this process, and recent genetic association studies point towards involvement of the phagocytosis and autophagy pathways. We developed a real-time tri-color flow cytometry method to quantitate the phagocytic function of human peripheral blood monocyte subsets including non-classic CD14(dim)CD16(+), intermediate CD14(+)CD16(+) and classic CD14(+)CD16(-) monocytes. Using this method, we have measured the phagocytic ability of fresh monocytes in a study of preclinical, prodromal and clinical AD, matched with cognitively normal healthy control subjects. Basal levels of phagocytosis in all three subsets of monocytes were similar between healthy controls and AD patients, while a significant increase of basal phagocytosis was found in subjects with high Aβ-amyloid burden as assessed by PET scans. Pre-treating cells with Copaxone (CPX, to stimulate phagocytosis) or ATP (an inhibitor of P2X7-mediated phagocytosis) showed a differential response depending on clinical or Aβ-burden status, indicating a relative functional deficit. Overall the results are consistent with a perturbation of basal and stimulated innate phagocytosis in sporadic AD.
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Affiliation(s)
- Ben J Gu
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia.
| | - Xin Huang
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Amber Ou
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Alan Rembach
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Christopher Fowler
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Pavan K Avula
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Adam Horton
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - James D Doecke
- CSIRO Health and Biosecurity/Australian E-Health Research Centre, Herston, QLD, 4029, Australia
| | - Victor L Villemagne
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
- Department of Nuclear Medicine and Centre for PET, Austin Health, Heidelberg, VIC, 3084, Australia
| | | | - Paul Maruff
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
- Cogstate Pty Ltd, Melbourne, VIC, 3000, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, 3010, Australia
| | - Robyn Guymer
- Centre for Eye Research Australia Royal Victorian Eye and Ear Hospital, The University of Melbourne, East Melbourne, VIC, 3002, Australia
| | - James S Wiley
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
| | - Colin L Masters
- The Florey Institute of Neuroscience & Mental Health, The University of Melbourne, 30 Royal Parade, Parkville, VIC, 3052, Australia
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Guo CX, Mat Nor MN, Danesh-Meyer HV, Vessey KA, Fletcher EL, O'Carroll SJ, Acosta ML, Green CR. Connexin43 Mimetic Peptide Improves Retinal Function and Reduces Inflammation in a Light-Damaged Albino Rat Model. Invest Ophthalmol Vis Sci 2016; 57:3961-73. [PMID: 27490318 DOI: 10.1167/iovs.15-16643] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Drugs that regulate connexin43 (Cx43) gap junction channels can reduce the spread of injury and improve functional outcomes after nervous system trauma. In the eye, Cx43 expression increases in the choroid following light damage. The aim of this study was to investigate whether Cx43 hemichannel block could preserve retinal function postinjury. METHODS Light damage was induced by exposure of adult albino Sprague-Dawley rats to 2700 Lux light for 24 hours. Intravitreal injections of a Cx43 mimetic peptide hemichannel blocker, Peptide5, or sham were administered 2 hours after the onset and at the end of the light damage period. Retinal function was assessed by electroretinogram and inflammatory responses in the choroid and retina were assessed using immunohistochemistry (ionized calcium binding adaptor molecule 1 [Iba-1], leukocyte common antigen [CD45], glial fibrillary acidic protein [GFAP]). RESULTS Light-damaged rat eyes had (1) reduced neuronal responses in both the rod and cone pathways and (2) marked inflammatory responses in the choroid and retina. Peptide5 significantly preserved function of photoreceptoral and postphotoreceptoral neurons in these animals. This was evident 24 hours after injury and 2 weeks later, as shown by improved mixed a-wave and mixed b-wave amplitudes, isolated rod PII and PIII amplitudes, and cone PII responses when compared with sham-treated controls. Retinal thinning and inflammation were also significantly reduced in Peptide5-treated eyes when compared with sham-treated controls. CONCLUSIONS Blocking Cx43 hemichannels after light damage can significantly improve functional outcomes of neurons in both the rod and cone photo-transduction pathways in the light-damaged animal model, likely by reducing choroid inflammation and suppressing the glial-mediated inflammatory response. These data may have relevance for the treatment of conditions such as diabetic retinopathy and age-related macular degeneration.
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Affiliation(s)
- Cindy X Guo
- School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand 2New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Mohd N Mat Nor
- School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand 2New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Helen V Danesh-Meyer
- New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand 3Department of Ophthalmology, University of Auckland, Auckland, New Zealand
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, University of Melbourne, Parkville, Australia
| | - Simon J O'Carroll
- Department of Anatomy and Medical Imaging, University of Auckland, Auckland, New Zealand
| | - Monica L Acosta
- School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand 2New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand
| | - Colin R Green
- New Zealand National Eye Centre, University of Auckland, Auckland, New Zealand 3Department of Ophthalmology, University of Auckland, Auckland, New Zealand
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Opie NL, van der Nagel NR, John SE, Vessey K, Rind GS, Ronayne SM, Fletcher EL, May CN, OBrien TJ, Oxley TJ. Micro-CT and Histological Evaluation of an Neural Interface Implanted Within a Blood Vessel. IEEE Trans Biomed Eng 2016; 64:928-934. [PMID: 27337706 DOI: 10.1109/tbme.2016.2552226] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Recently, we reported the development of a stent-mounted electrode array (Stentrode) capable of chronically recording neural signals from within a blood vessel with high fidelity. Preliminary data suggested incorporation of the Stentrode into the blood vessel wall was associated with improved recording sensitivity. We now investigate neointimal incorporation of the Stentrode, implanted in a cohort of sheep for up to 190 days. METHODS Micro-CT, obtained from the Imaging and Medical Beamline at the Australian Synchrotron, and histomorphometic techniques developed specifically for evaluation of cerebral vasculature implanted with a stent-electrode array were compared as measures to assess device incorporation and vessel patency. RESULTS Both micro-CT analysis and histomorphometry, revealed a strong correlation between implant duration and the number of incorporated stent struts. <10% (26/268) of stent struts were covered in neointima in sheep implanted for <2 weeks, increasing to >78% (191/243) between 2 and 4 weeks. Average strut-to-lumen thickness from animals implanted >12 weeks was comparable across both modalities, 339 ±15 μm measured using micro-CT and 331 ±19 μm ( n = 292) measured histologically. There was a strong correlation between lumen areas measured using the two modalities ( ), with no observation of vessel occlusion observed from any of the 12 animals implanted for up to 190 days. CONCLUSION Micro-CT and the histomorphometric techniques we developed are comparable and can both be used to identify incorporation of a Stentrode implanted in cerebral vessels. SIGNIFICANCE This study demonstrates preliminary safety of a stent-electrode array implanted in cerebral vasculature, which may facilitate technological advances in minimally invasive brain-computer interfaces.
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Greferath U, Guymer RH, Vessey KA, Brassington K, Fletcher EL. Correlation of Histologic Features with In Vivo Imaging of Reticular Pseudodrusen. Ophthalmology 2016; 123:1320-31. [DOI: 10.1016/j.ophtha.2016.02.009] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Revised: 02/04/2016] [Accepted: 02/04/2016] [Indexed: 02/06/2023] Open
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Aplin FP, Vessey KA, Luu CD, Guymer RH, Shepherd RK, Fletcher EL. Retinal Changes in an ATP-Induced Model of Retinal Degeneration. Front Neuroanat 2016; 10:46. [PMID: 27199678 PMCID: PMC4850166 DOI: 10.3389/fnana.2016.00046] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/11/2016] [Indexed: 11/20/2022] Open
Abstract
In rodents and felines, intravitreal administration of adenosine triphosphate (ATP) has been shown to induce photoreceptor death providing a tractable model of retinal degeneration in these species. This study investigated the long term effects of photoreceptor loss in an ATP induced feline model of retinal degeneration. Six normal sighted felines were unilaterally blinded using intravitreal ATP injections and assessed using electroretinography (ERG) and optical coherence tomography (OCT). At 30 h (n = 3) or 12 weeks (n = 3) post-injection, the animals were euthanized and the eyes enucleated. Retinae were sectioned and labeled using immunohistochemistry for markers of cell death, neural remodeling and gliosis. Ongoing cell death and retinal degeneration was observed in the outer retina at both 30 h and 12 weeks following unilateral ATP injection. Markers of mid to late-stage retinal remodeling such as cell displacement and aberrant neurite growth were observed in the inner retina at 12 weeks post-injection. Ganglion cells appeared to remain intact in ATP injected eyes. Müller cell gliosis was observed throughout the inner and outer retina, in some parts completely enveloping and/or displacing the surviving neural tissue. Our data suggests that the ATP injected feline retina continues to undergo progressive retinal degeneration and exhibits abnormalities consistent with a description of retinal remodeling commonly seen in other models of retinal degeneration. These findings validate the use of intravitreal ATP injection in feline as a large animal model of retinal degeneration which may aid in development of therapies aiming to restore visual function after photoreceptor degeneration.
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Affiliation(s)
- Felix P Aplin
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East MelbourneMelbourne, VIC, Australia; Department of Anatomy and Neuroscience, The University of MelbourneMelbourne, VIC, Australia; The Bionics Institute, East MelbourneMelbourne, VIC, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne Melbourne, VIC, Australia
| | - Chi D Luu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East MelbourneMelbourne, VIC, Australia; Department of Surgery (Ophthalmology), The University of MelbourneParkville, VIC, Australia
| | - Robyn H Guymer
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East MelbourneMelbourne, VIC, Australia; Department of Surgery (Ophthalmology), The University of MelbourneParkville, VIC, Australia
| | - Robert K Shepherd
- The Bionics Institute, East MelbourneMelbourne, VIC, Australia; Medical Bionics Department, The University of MelbourneMelbourne, VIC, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne Melbourne, VIC, Australia
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Saha S, Greferath U, Vessey KA, Grayden DB, Burkitt AN, Fletcher EL. Changes in ganglion cells during retinal degeneration. Neuroscience 2016; 329:1-11. [PMID: 27132232 DOI: 10.1016/j.neuroscience.2016.04.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2016] [Revised: 04/05/2016] [Accepted: 04/21/2016] [Indexed: 10/21/2022]
Abstract
Inherited retinal degeneration such as retinitis pigmentosa (RP) is associated with photoreceptor loss and concomitant morphological and functional changes in the inner retina. It is not known whether these changes are associated with changes in the density and distribution of synaptic inputs to retinal ganglion cells (RGCs). We quantified changes in ganglion cell density in rd1 and age-matched C57BL/6J-(wildtype, WT) mice using the immunocytochemical marker, RBPMS. Our data revealed that following complete loss of photoreceptors, (∼3months of age), there was a reduction in ganglion cell density in the peripheral retina. We next examined changes in synaptic inputs to A type ganglion cells by performing double labeling experiments in mice with the ganglion cell reporter lines, rd1-Thy1 and age-matched wildtype-Thy1. Ribbon synapses were identified by co-labelling with CtBP2 (RIBEYE) and conventional synapses with the clustering molecule, gephyrin. ON RGCs showed a significant reduction in RIBEYE-immunoreactive synapse density while OFF RGCs showed a significant reduction in the gephyrin-immmunoreactive synapse density. Distribution patterns of both synaptic markers across the dendritic trees of RGCs were unchanged. The change in synaptic inputs to RGCs was associated with a reduction in the number of immunolabeled rod bipolar and ON cone bipolar cells. These results suggest that functional changes reported in ganglion cells during retinal degeneration could be attributed to loss of synaptic inputs.
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Affiliation(s)
- Susmita Saha
- Department of Anatomy and Neuroscience, The University of Melbourne, Australia; NeuroEngineering Laboratory, Department of Electrical & Electronic Engineering, The University of Melbourne, Australia; Centre for Neural Engineering, The University of Melbourne, Australia
| | - Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Australia
| | - David B Grayden
- NeuroEngineering Laboratory, Department of Electrical & Electronic Engineering, The University of Melbourne, Australia; Centre for Neural Engineering, The University of Melbourne, Australia; NICTA Victoria Research Laboratory, c/- Dept. of Electrical & Electronic Engineering, The University of Melbourne, Australia; Bionics Institute, East Melbourne, Australia
| | - Anthony N Burkitt
- NeuroEngineering Laboratory, Department of Electrical & Electronic Engineering, The University of Melbourne, Australia; Centre for Neural Engineering, The University of Melbourne, Australia; NICTA Victoria Research Laboratory, c/- Dept. of Electrical & Electronic Engineering, The University of Melbourne, Australia; Bionics Institute, East Melbourne, Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Australia.
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Kalloniatis M, Nivison-Smith L, Chua J, Acosta ML, Fletcher EL. Using the rd1 mouse to understand functional and anatomical retinal remodelling and treatment implications in retinitis pigmentosa: A review. Exp Eye Res 2015; 150:106-21. [PMID: 26521764 DOI: 10.1016/j.exer.2015.10.019] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 10/22/2015] [Accepted: 10/23/2015] [Indexed: 12/31/2022]
Abstract
Retinitis Pigmentosa (RP) reflects a range of inherited retinal disorders which involve photoreceptor degeneration and retinal pigmented epithelium dysfunction. Despite the multitude of genetic mutations being associated with the RP phenotype, the clinical and functional manifestations of the disease remain the same: nyctalopia, visual field constriction (tunnel vision), photopsias and pigment proliferation. In this review, we describe the typical clinical phenotype of human RP and review the anatomical and functional remodelling which occurs in RP determined from studies in the rd/rd (rd1) mouse. We also review studies that report a slowing down or show an acceleration of retinal degeneration and finally we provide insights on the impact retinal remodelling may have in vision restoration strategies.
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Affiliation(s)
- M Kalloniatis
- Centre for Eye Health, University of New South Wales, Kensington, NSW, Australia; School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, Australia; School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand; Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria, Australia.
| | - L Nivison-Smith
- Centre for Eye Health, University of New South Wales, Kensington, NSW, Australia; School of Optometry and Vision Science, University of New South Wales, Kensington, NSW, Australia
| | - J Chua
- School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
| | - M L Acosta
- School of Optometry and Vision Science, University of Auckland, Auckland, New Zealand
| | - E L Fletcher
- Department of Anatomy and Neuroscience, University of Melbourne, Melbourne, Victoria, Australia
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Ho T, Jobling AI, Greferath U, Chuang T, Ramesh A, Fletcher EL, Vessey KA. Vesicular expression and release of ATP from dopaminergic neurons of the mouse retina and midbrain. Front Cell Neurosci 2015; 9:389. [PMID: 26500494 PMCID: PMC4593860 DOI: 10.3389/fncel.2015.00389] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 09/17/2015] [Indexed: 12/20/2022] Open
Abstract
Vesicular nucleotide transporter (VNUT) is required for active accumulation of adenosine tri-phosphate (ATP) into vesicles for purinergic neurotransmission, however, the cell types that express VNUT in the central nervous system remain unknown. This study characterized VNUT expression within the mammalian retina and brain and assessed a possible functional role in purinergic signaling. Two native isoforms of VNUT were detected in mouse retina and brain based on RNA transcript and protein analysis. Using immunohistochemistry, VNUT was found to co-localize with tyrosine hydroxylase (TH) positive, dopaminergic (DA) neurons of the substantia nigra and ventral tegmental area, however, VNUT expression in extranigral non-DA neurons was also observed. In the retina, VNUT labeling was found to co-localize solely with TH-positive DA-cells. In the outer retina, VNUT-positive interplexiform cell processes were in close contact with horizontal cells and cone photoreceptor terminals, which are known to express P2 purinergic-receptors. In order to assess function, dissociated retinal neurons were loaded with fluorescent ATP markers (Quinacrine or Mant-ATP) and the DA marker FFN102, co-labeled with a VNUT antibody and imaged in real time. Fluorescent ATP markers and FFN102 puncta were found to co-localize in VNUT positive neurons and upon stimulation with high potassium, ATP marker fluorescence at the cell membrane was reduced. This response was blocked in the presence of cadmium. These data suggest DA neurons co-release ATP via calcium dependent exocytosis and in the retina this may modulate the visual response by activating purine receptors on closely associated neurons.
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Affiliation(s)
- Tracy Ho
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
| | - Andrew I Jobling
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
| | - Ursula Greferath
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
| | - Trinette Chuang
- Polyclonal Antibody Development, R&D Antibody Development, EMD Millipore Temecula, CA, USA
| | - Archana Ramesh
- Polyclonal Antibody Development, R&D Antibody Development, EMD Millipore Temecula, CA, USA
| | - Erica L Fletcher
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
| | - Kirstan A Vessey
- Visual Neuroscience Laboratory, Department of Anatomy and Neuroscience, The University of Melbourne Parkville, VIC, Australia
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Tran M, Young ME, Jefferies AJ, Hryciw DH, Ward MM, Fletcher EL, Wlodek ME, Wadley GD. Uteroplacental insufficiency leads to hypertension, but not glucose intolerance or impaired skeletal muscle mitochondrial biogenesis, in 12-month-old rats. Physiol Rep 2015; 3:3/9/e12556. [PMID: 26416974 PMCID: PMC4600396 DOI: 10.14814/phy2.12556] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Growth restriction impacts on offspring development and increases their risk of disease in adulthood which is exacerbated with “second hits.” The aim of this study was to investigate if blood pressure, glucose tolerance, and skeletal muscle mitochondrial biogenesis were altered in 12-month-old male and female offspring with prenatal or postnatal growth restriction. Bilateral uterine vessel ligation induced uteroplacental insufficiency and growth restriction in offspring (Restricted). A sham surgery was also performed during pregnancy (Control) and some litters from sham mothers had their litter size reduced (Reduced litter), which restricted postnatal growth. Growth-restricted females only developed hypertension at 12 months, which was not observed in males. In Restricted females only homeostasis model assessment for insulin resistance was decreased, indicating enhanced hepatic insulin sensitivity, which was not observed in males. Plasma leptin was increased only in the Reduced males at 12 months compared to Control and Restricted males, which was not observed in females. Compared to Controls, leptin, ghrelin, and adiponectin were unaltered in the Restricted males and females, suggesting that at 12 months of age the reduction in body weight in the Restricted offspring is not a consequence of circulating adipokines. Skeletal muscle PGC-1α levels were unaltered in 12-month-old male and female rats, which indicate improvements in lean muscle mass by 12 months of age. In summary, sex strongly impacts the cardiometabolic effects of growth restriction in 12-month-old rats and it is females who are at particular risk of developing long-term hypertension following growth restriction.
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Affiliation(s)
- Melanie Tran
- Departments of Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Margaret E Young
- Departments of Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Andrew J Jefferies
- Departments of Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Deanne H Hryciw
- Departments of Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Michelle M Ward
- Departments of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia
| | - Erica L Fletcher
- Departments of Anatomy and Neuroscience, The University of Melbourne, Parkville, Victoria, Australia
| | - Mary E Wlodek
- Departments of Physiology, The University of Melbourne, Parkville, Victoria, Australia
| | - Glenn D Wadley
- Departments of Physiology, The University of Melbourne, Parkville, Victoria, Australia School of Exercise and Nutrition Sciences, Centre for Physical Activity and Nutrition Research, Deakin University, Burwood, Victoria, Australia
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Greferath U, Anderson EE, Jobling AI, Vessey KA, Martinez G, de Iongh RU, Kalloniatis M, Fletcher EL. Inner retinal change in a novel rd1-FTL mouse model of retinal degeneration. Front Cell Neurosci 2015; 9:293. [PMID: 26283925 PMCID: PMC4518195 DOI: 10.3389/fncel.2015.00293] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 07/16/2015] [Indexed: 11/13/2022] Open
Abstract
While photoreceptor loss is the most devastating result of inherited retinal degenerations such as retinitis pigmentosa, inner retinal neurons also undergo significant alteration. Detailing these changes has become important as many vision restorative therapies target the remaining neurons. In this study, the rd1-Fos-Tau-LacZ (rd1-FTL) mouse model was used to explore inner retinal change at a late stage of retinal degeneration, after the loss of photoreceptor nuclei. The rd1-FTL model carries a mutation in the phosphodiesterase gene, Pde6b, and an axonally targeted transgenic beta galactosidase reporter system under the control of the c-fos promoter. Retinae of transgenic rd1-FTL mice and control FTL animals aged 2-12 months were processed for indirect fluorescence immunocytochemistry. At 2 months of age, a time when the majority of photoreceptor nuclei are lost, there was negligible c-fos reporter (FTL) expression, however, from 4 months, reporter expression was observed to increase within subpopulations of amacrine and ganglion cells within the central retina. These areas of inner retinal FTL expression coincided with regions that contained aberrant Müller cells. Specifically, these cells exhibited reduced glutamine synthetase and Kir4.1 immunolabelling, whilst showing evidence of proliferative gliosis (increased cyclinD1 and glial fibrillary acidic protein expression). These changes were limited to distinct regions where cone photoreceptor terminals were absent. Overall, these results highlight that distinct areas of the rd1-FTL central retina undergo significant glial alterations after cone photoreceptor loss. These areas coincide with up-regulation of the c-fos reporter in the inner retina, which may represent a change in neuronal function/plasticity. The rd1-FTL mouse is a useful model system to probe changes that occur in the inner retina at later stages of retinal degeneration.
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Affiliation(s)
- Ursula Greferath
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC Australia
| | - Emily E Anderson
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC Australia
| | - Andrew I Jobling
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC Australia
| | - Kirstan A Vessey
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC Australia
| | - Gemma Martinez
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC Australia
| | - Robb U de Iongh
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC Australia
| | - Michael Kalloniatis
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC Australia ; Centre for Eye Health and School of Optometry and Vision Science, University of New South Wales, Sydney, NSW Australia
| | - Erica L Fletcher
- Department of Anatomy and Neuroscience, The University of Melbourne, Melbourne, VIC Australia
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