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Chou TH, Hao Z, Alba D, Lazo A, Gallo Afflitto G, Eastwood JD, Porciatti V, Guy J, Yu H. Mitochondrially Targeted Gene Therapy Rescues Visual Loss in a Mouse Model of Leber's Hereditary Optic Neuropathy. Int J Mol Sci 2023; 24:17068. [PMID: 38069388 PMCID: PMC10707051 DOI: 10.3390/ijms242317068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Revised: 11/26/2023] [Accepted: 11/29/2023] [Indexed: 12/18/2023] Open
Abstract
Leber's hereditary optic neuropathy (LHON) is a common mitochondrial genetic disease, causing irreversible blindness in young individuals. Current treatments are inadequate, and there is no definitive cure. This study evaluates the effectiveness of delivering wildtype human NADH ubiquinone oxidoreductase subunit 4 (hND4) gene using mito-targeted AAV(MTSAAV) to rescue LHOH mice. We observed a declining pattern in electroretinograms amplitudes as mice aged across all groups (p < 0.001), with significant differences among groups (p = 0.023; Control vs. LHON, p = 0.008; Control vs. Rescue, p = 0.228). Inner retinal thickness and intraocular pressure did not change significantly with age or groups. Compared to LHON mice, those rescued with wildtype hND4 exhibited improved retinal visual acuity (0.29 ± 0.1 cy/deg vs. 0.15 ± 0.1 cy/deg) and increased functional hyperemia response (effect of flicker, p < 0.001, effect of Group, p = 0.004; Interaction Flicker × Group, p < 0.001). Postmortem analysis shows a marked reduction in retinal ganglion cell density in the LHON group compared to the other groups (Effect of Group, p < 0.001, Control vs. LHON, p < 0.001, Control vs. Rescue, p = 0.106). These results suggest that MTSAAV-delivered wildtype hND4 gene rescues, at least in part, visual impairment in an LHON mouse model and has the therapeutic potential to treat this disease.
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Affiliation(s)
| | | | | | | | | | | | - Vittorio Porciatti
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (T.-H.C.); (Z.H.); (D.A.); (A.L.); (G.G.A.); (J.D.E.); (J.G.)
| | | | - Hong Yu
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA; (T.-H.C.); (Z.H.); (D.A.); (A.L.); (G.G.A.); (J.D.E.); (J.G.)
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2
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Nilsson G, Mottahedin A, Zelco A, Lauschke VM, Ek CJ, Song J, Ardalan M, Hua S, Zhang X, Mallard C, Hagberg H, Leavenworth JW, Wang X. Two different isoforms of osteopontin modulate myelination and axonal integrity. FASEB Bioadv 2023; 5:336-353. [PMID: 37554545 PMCID: PMC10405251 DOI: 10.1096/fba.2023-00030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 05/22/2023] [Accepted: 06/06/2023] [Indexed: 08/10/2023] Open
Abstract
Abnormal myelination underlies the pathology of white matter diseases such as preterm white matter injury and multiple sclerosis. Osteopontin (OPN) has been suggested to play a role in myelination. Murine OPN mRNA is translated into a secreted isoform (sOPN) or an intracellular isoform (iOPN). Whether there is an isoform-specific involvement of OPN in myelination is unknown. Here we generated mouse models that either lacked both OPN isoforms in all cells (OPN-KO) or lacked sOPN systemically but expressed iOPN specifically in oligodendrocytes (OLs-iOPN-KI). Transcriptome analysis of isolated oligodendrocytes from the neonatal brain showed that genes and pathways related to increase of myelination and altered cell cycle control were enriched in the absence of the two OPN isoforms in OPN-KO mice compared to control mice. Accordingly, adult OPN-KO mice showed an increased axonal myelination, as revealed by transmission electron microscopy imaging, and increased expression of myelin-related proteins. In contrast, neonatal oligodendrocytes from OLs-iOPN-KI mice compared to control mice showed differential regulation of genes and pathways related to the increase of cell adhesion, motility, and vasculature development, and the decrease of axonal/neuronal development. OLs-iOPN-KI mice showed abnormal myelin formation in the early phase of myelination in young mice and signs of axonal degeneration in adulthood. These results suggest an OPN isoform-specific involvement, and a possible interplay between the isoforms, in myelination, and axonal integrity. Thus, the two isoforms of OPN need to be separately considered in therapeutic strategies targeting OPN in white matter injury and diseases.
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Affiliation(s)
- Gisela Nilsson
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Amin Mottahedin
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Aura Zelco
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Volker M. Lauschke
- Department of Physiology and PharmacologyKarolinska InstituteStockholmSweden
- Dr Margarete Fischer‐Bosch Institute of Clinical PharmacologyStuttgartGermany
- University of TübingenTübingenGermany
| | - C. Joakim Ek
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Juan Song
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
- Henan Key Laboratory of Child Brain InjuryInstitute of Neuroscience and Third Affiliated Hospital of Zhengzhou UniversityZhengzhouChina
| | - Maryam Ardalan
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Sha Hua
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
- Department of Cardiology, Ruijin Hospital/Luwan Branch, School of MedicineShanghai Jiao Tong UniversityShanghaiChina
| | - Xiaoli Zhang
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
- Henan Key Laboratory of Child Brain InjuryInstitute of Neuroscience and Third Affiliated Hospital of Zhengzhou UniversityZhengzhouChina
| | - Carina Mallard
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Henrik Hagberg
- Centre of Perinatal Medicine & Health, Department of Obstetrics and Gynaecology, Institute of Clinical Sciences, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
| | - Jianmei W. Leavenworth
- Department of NeurosurgeryUniversity of Alabama at BirminghamBirminghamAlabamaUSA
- Department of MicrobiologyUniversity of Alabama at BirminghamBirminghamAlabamaUSA
| | - Xiaoyang Wang
- Centre of Perinatal Medicine & Health, Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
- Henan Key Laboratory of Child Brain InjuryInstitute of Neuroscience and Third Affiliated Hospital of Zhengzhou UniversityZhengzhouChina
- Centre of Perinatal Medicine & Health, Department of Obstetrics and Gynaecology, Institute of Clinical Sciences, Sahlgrenska AcademyUniversity of GothenburgGothenburgSweden
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3
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Steele EP, Laidre ME. Wild social behavior differs following experimental loss of vision in social hermit crabs. THE SCIENCE OF NATURE - NATURWISSENSCHAFTEN 2023; 110:20. [PMID: 37199869 DOI: 10.1007/s00114-023-01847-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 02/20/2023] [Accepted: 05/02/2023] [Indexed: 05/19/2023]
Abstract
Even for animals with multiple senses at their disposal, there may be a strong reliance on a single sense, like vision, for social behavior. Experimentally blocking or eliminating vision offers a powerful means of testing impacts on social behavior, though few studies have followed experimentally blinded individuals in the wild to test potential changes in social behavior in natural settings. Here we conducted experiments with social hermit crabs (Coenobita compressus), applying opaque material overtop their eyes to temporarily blind individuals. We then released these experimentally blinded individuals and non-blinded control individuals into the wild as well as into captive social settings. Compared to control individuals, experimentally blinded individuals initiated significantly fewer social contacts with conspecifics in the wild. These experimentally blinded individuals were not, however, differentially targeted by conspecifics. Interestingly, unlike the wild experiments, the captive experiments showed no differences in social behavior between experimentally blinded and non-blinded control individuals, suggesting that experiments in natural settings in the wild may be essential to fully unraveling impacts of blindness on social behavior. Broadly, for social animals that are highly reliant on the visual modality, social behavior may change dramatically if they lose their vision.
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Affiliation(s)
- Elliott P Steele
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH, 03755, USA.
- Graduate Program in Ecology, Evolution, Environment, and Society, Dartmouth College, Hanover, NH, 03755, USA.
| | - Mark E Laidre
- Department of Biological Sciences, Dartmouth College, 78 College Street, Hanover, NH, 03755, USA.
- Graduate Program in Ecology, Evolution, Environment, and Society, Dartmouth College, Hanover, NH, 03755, USA.
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Di Pierdomenico J, Henderson DCM, Giammaria S, Smith VL, Jamet AJ, Smith CA, Hooper ML, Chauhan BC. Age and intraocular pressure in murine experimental glaucoma. Prog Retin Eye Res 2021; 88:101021. [PMID: 34801667 DOI: 10.1016/j.preteyeres.2021.101021] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/25/2021] [Accepted: 11/08/2021] [Indexed: 12/23/2022]
Abstract
Age and intraocular pressure (IOP) are the two most important risk factors for the development and progression of open-angle glaucoma. While IOP is commonly considered in models of experimental glaucoma (EG), most studies use juvenile or adult animals and seldom older animals which are representative of the human disease. This paper provides a concise review of how retinal ganglion cell (RGC) loss, the hallmark of glaucoma, can be evaluated in EG with a special emphasis on serial in vivo imaging, a parallel approach used in clinical practice. It appraises the suitability of EG models for the purpose of in vivo imaging and argues for the use of models that provide a sustained elevation of IOP, without compromise of the ocular media. In a study with parallel cohorts of adult (3-month-old, equivalent to 20 human years) and old (2-year-old, equivalent to 70 human years) mice, we compare the effects of elevated IOP on serial ganglion cell complex thickness and individual RGC dendritic morphology changes obtained in vivo. We also evaluate how age modulates the impact of elevated IOP on RGC somal and axonal density in histological analysis as well the density of melanopsin RGCs. We discuss the challenges of using old animals and emphasize the potential of single RGC imaging for understanding the pathobiology of RGC loss and evaluating new therapeutic avenues.
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Affiliation(s)
- Johnny Di Pierdomenico
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Delaney C M Henderson
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Sara Giammaria
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Victoria L Smith
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Aliénor J Jamet
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Corey A Smith
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Michele L Hooper
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Balwantray C Chauhan
- Retina and Optic Nerve Research Laboratory, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Medical Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Physiology and Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.
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Tribble JR, Otmani A, Kokkali E, Lardner E, Morgan JE, Williams PA. Retinal Ganglion Cell Degeneration in a Rat Magnetic Bead Model of Ocular Hypertensive Glaucoma. Transl Vis Sci Technol 2021; 10:21. [PMID: 33510960 PMCID: PMC7804499 DOI: 10.1167/tvst.10.1.21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 12/02/2020] [Indexed: 01/22/2023] Open
Abstract
Purpose Glaucoma remains a leading cause of irreversible blindness worldwide. Animal glaucoma models replicate high intraocular pressure, a risk factor for glaucoma, to induce retinal ganglion cell (RGC) degeneration. We describe an inducible, magnetic bead model in the Brown Norway rat in which we are able to determine degeneration across multiple RGC compartments at a time point that is appropriate for investigating neurodegenerative events and potential treatment effects. Methods We induced ocular hypertension through injection of magnetic microspheres into the anterior chamber of Brown Norway rats; un-operated (naïve) rats served as controls. Intraocular pressure was recorded, and eye diameter measurements were taken before surgery and at the terminal end points. We assessed RGC degeneration and vascular changes through immunofluorescence, and axon transport to terminal brain thalami through intravitreal injection of fluorophore-conjugated cholera toxin subunit β. Results We observed clinically relevant features of disease accompanying RGC cell somal, axonal, and dendritic loss. RGC axonal dysfunction persisted along the trajectory of the cell into the terminal brain thalami, with clear disruption at the optic nerve head. We also observed vascular compromise consistent with human disease, as well as an expansion of global eye size with ocular hypertension. Conclusions The magnetic bead model in the Brown Norway rat recapitulates many clinically relevant disease features of human glaucoma, including degeneration across multiple RGC compartments. Eye expansion is likely a result of rodent scleral elasticity, and we caution that this should be considered when assessing retinal density measurements. Translational Relevance This model offers a disease-relevant platform that will allow for assessment of glaucoma-relevant therapeutics.
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Affiliation(s)
- James R Tribble
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Amin Otmani
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Eirini Kokkali
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, UK
| | - Emma Lardner
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - James E Morgan
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, UK.,School of Medicine, Cardiff University, Cardiff, Wales, UK
| | - Pete A Williams
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
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Tribble JR, Kokkali E, Otmani A, Plastino F, Lardner E, Vohra R, Kolko M, André H, Morgan JE, Williams PA. When Is a Control Not a Control? Reactive Microglia Occur Throughout the Control Contralateral Pathway of Retinal Ganglion Cell Projections in Experimental Glaucoma. Transl Vis Sci Technol 2021; 10:22. [PMID: 33510961 PMCID: PMC7804521 DOI: 10.1167/tvst.10.1.22] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 12/02/2020] [Indexed: 12/19/2022] Open
Abstract
Purpose Animal models show retinal ganglion cell (RGC) injuries that replicate features of glaucoma and the contralateral eye is commonly used as an internal control. There is significant crossover of RGC axons from the ipsilateral to the contralateral side at the level of the optic chiasm, which may confound findings when damage is restricted to one eye. The effect of unilateral glaucoma on neuroinflammatory damage to the contralateral pathway of RGC projections has largely been unexplored. Methods Ocular hypertensive glaucoma was induced unilaterally or bilaterally in the rat and RGC neurodegenerative events were assessed. Neuroinflammation was quantified in the retina, optic nerve head, optic nerve, lateral geniculate nucleus, and superior colliculus by high-resolution imaging, and in the retina by flow cytometry and protein arrays. Results After ocular hypertensive stress, peripheral monocytes enter the retina and microglia become reactive. This effect is more marked in animals with bilateral ocular hypertensive glaucoma. In rats where glaucoma was induced unilaterally, there was significant microglia activation in the contralateral (control) eye. Microglial activation extended into the optic nerve and terminal visual thalami, where it was similar across hemispheres in unilateral ocular hypertension. Conclusions These data suggest that caution is warranted when using the contralateral eye as a control and in comparing visual thalami in unilateral models of glaucoma. Translational Relevance The use of a contralateral eye as a control may confound the discovery of human-relevant mechanism and treatments in animal models. We also identify neuroinflammatory protein responses that warrant further investigation as potential disease-modifiable targets.
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Affiliation(s)
- James R. Tribble
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Eirini Kokkali
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, UK
| | - Amin Otmani
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Flavia Plastino
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Emma Lardner
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - Rupali Vohra
- Department of Veterinary and Animal Sciences, Pathobiological Sciences, University of Copenhagen, Denmark
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Miriam Kolko
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
- Department of Ophthalmology, Rigshospitalet-Glostrup, Copenhagen, Denmark
| | - Helder André
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
| | - James E. Morgan
- School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, UK
- School of Medicine, Cardiff University, Cardiff, Wales, UK
| | - Pete A. Williams
- Department of Clinical Neuroscience, Division of Eye and Vision, St. Erik Eye Hospital, Karolinska Institutet, Stockholm, Sweden
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Zhang X, Li CX, Yan Y, Nair G, Rilling JK, Herndon JG, Preuss TM, Hu X, Li L. In-vivo diffusion MRI protocol optimization for the chimpanzee brain and examination of aging effects on the primate optic nerve at 3T. Magn Reson Imaging 2020; 77:194-203. [PMID: 33359631 DOI: 10.1016/j.mri.2020.12.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 10/30/2020] [Accepted: 12/20/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND Diffusion MRI (dMRI) data acquisition protocols are well-established on modern high-field clinical scanners for human studies. However, these protocols are not suitable for the chimpanzee (or other large-brained mammals) because of its substantial difference in head geometry and brain volume compared with humans. Therefore, an optimal dMRI data acquisition protocol dedicated to chimpanzee neuroimaging is needed. METHODS A multi-shot (4 segments) double spin-echo echo-planar imaging (MS-EPI) sequence and a single-shot double spin-echo EPI (SS-EPI) sequence were optimized separately for in vivo dMRI data acquisition of chimpanzees using a clinical 3T scanner. Correction for severe susceptibility-induced image distortion and signal drop-off of the chimpanzee brain was performed and evaluated using FSL software. DTI indices in different brain regions and probabilistic tractography were compared. A separate DTI data set from n=34 chimpanzees (13 to 56 years old) was collected using the optimal protocol. Age-related changes in diffusivity indices of optic nerve fibers were evaluated. RESULTS The SS-EPI sequence acquired dMRI data of the chimpanzee brain with approximately doubled the SNR as the MS-EPI sequence given the same scan time. The quality of white matter fiber tracking from the SS-EPI data was much higher than that from MS-EPI data. However, quantitative analysis of DTI indices showed no difference in most ROIs between the SS-EPI and MS-EPI sequences. The progressive evolution of diffusivity indices of optic nerves indicated mild changes in fiber bundles of chimpanzees aged 40 years and above. CONCLUSION The single-shot EPI-based acquisition protocol provided better image quality of dMRI for chimpanzee brains and is recommended for in vivo dMRI study or clinical diagnosis of chimpanzees (or other large animals) using a clinical scanner. Also, the tendency of FA decrease or diffusivity increase in the optic nerve of aged chimpanzees was seen but did not show significant age-related changes, suggesting aging may have less impact on optic nerve fiber integrity of chimpanzees, in contrast to previous results for both macaque monkeys and humans.
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Affiliation(s)
- Xiaodong Zhang
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America; Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America.
| | - Chun-Xia Li
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America
| | - Yumei Yan
- Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America
| | - Govind Nair
- qMRI Core Facility, NINDS, NIH, Bethesda, MD 20892, United States of America
| | - James K Rilling
- Department of Anthropology, Emory University, Atlanta, GA, United States of America; Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America
| | - James G Herndon
- Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America
| | - Todd M Preuss
- Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, GA, United States of America
| | - Xiaoping Hu
- Dept of Bioengineering, University of California, Riverside, CA, United States of America
| | - Longchuan Li
- Marcus Autism Center, Children's Healthcare of Atlanta, Emory University, Atlanta, GA, United States of America.
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Ramírez AI, Fernández-Albarral JA, Hoz RD, López-Cuenca I, Salobrar-García E, Rojas P, Valiente-Soriano FJ, Avilés-Trigueros M, Villegas-Pérez MP, Vidal-Sanz M, Triviño A, Salazar JJ, Ramírez JM. Microglial changes in the early aging stage in a healthy retina and an experimental glaucoma model. PROGRESS IN BRAIN RESEARCH 2020; 256:125-149. [PMID: 32958210 DOI: 10.1016/bs.pbr.2020.05.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Glaucoma is an age-related neurodegenerative disease that begins at the onset of aging. In this disease, there is an involvement of the immune system and therefore of the microglia. The purpose of this study is to evaluate the microglial activation using a mouse model of ocular hypertension (OHT) at the onset of aging. For this purpose, we used both naive and ocular hypertensives of 15-month-old mice (early stage of aging). In the latter, we analyzed the OHT eyes and the eyes contralateral to them to compare them with their aged controls. In the eyes of aged naive, aged OHT and aged contralateral eyes, microglial changes were observed compared to the young mice, including: (i) aged naive vs young naive: An increased soma size and vertical processes; (ii) aged OHT eyes vs young OHT eyes: A decrease in the area of the retina occupied by Iba-1 cells and in vertical processes; and (iii) aged contralateral vs young contralateral: A decrease in the soma size and arbor area and an increase in the number of microglia in the outer segment layer. Aged OHT eyes and the eyes contralateral to them showed an up-regulation of the CD68 expression in the branched microglia and a down-regulation in the MHCII and P2RY12 expression with respect to the eyes of young OHT mice. Conclusion: in the early phase of aging, morphological microglial changes along with changes in the expression of MHCII, CD68 and P2RY12, in both naive and OHT mice. These changes appear in aged OHT eyes and the eyes contralateral to them eyes.
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Affiliation(s)
- Ana I Ramírez
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain; Facultad de Óptica y Optometría, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, Madrid, Spain
| | - José A Fernández-Albarral
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain
| | - Rosa de Hoz
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain; Facultad de Óptica y Optometría, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, Madrid, Spain
| | - Inés López-Cuenca
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain
| | - Elena Salobrar-García
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain; Facultad de Óptica y Optometría, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, Madrid, Spain
| | - Pilar Rojas
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain; Hospital General Universitario Gregorio Marañón, Instituto Oftálmico de Madrid, Madrid, Spain
| | - Francisco Javier Valiente-Soriano
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - Marcelino Avilés-Trigueros
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - María Paz Villegas-Pérez
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - Manuel Vidal-Sanz
- Department of Ophthalmology, University of Murcia and Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain
| | - Alberto Triviño
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain; Facultad de Medicina, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, Spain
| | - Juan J Salazar
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain; Facultad de Óptica y Optometría, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, Madrid, Spain.
| | - José M Ramírez
- Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Universidad Complutense de Madrid, Madrid, Spain; Facultad de Medicina, Departamento de Inmunología, Oftalmología y ORL, Universidad Complutense de Madrid, Spain.
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Ritch MD, Hannon BG, Read AT, Feola AJ, Cull GA, Reynaud J, Morrison JC, Burgoyne CF, Pardue MT, Ethier CR. AxoNet: A deep learning-based tool to count retinal ganglion cell axons. Sci Rep 2020; 10:8034. [PMID: 32415269 PMCID: PMC7228952 DOI: 10.1038/s41598-020-64898-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 04/21/2020] [Indexed: 11/15/2022] Open
Abstract
In this work, we develop a robust, extensible tool to automatically and accurately count retinal ganglion cell axons in optic nerve (ON) tissue images from various animal models of glaucoma. We adapted deep learning to regress pixelwise axon count density estimates, which were then integrated over the image area to determine axon counts. The tool, termed AxoNet, was trained and evaluated using a dataset containing images of ON regions randomly selected from whole cross sections of both control and damaged rat ONs and manually annotated for axon count and location. This rat-trained network was then applied to a separate dataset of non-human primate (NHP) ON images. AxoNet was compared to two existing automated axon counting tools, AxonMaster and AxonJ, using both datasets. AxoNet outperformed the existing tools on both the rat and NHP ON datasets as judged by mean absolute error, R2 values when regressing automated vs. manual counts, and Bland-Altman analysis. AxoNet does not rely on hand-crafted image features for axon recognition and is robust to variations in the extent of ON tissue damage, image quality, and species of mammal. Therefore, AxoNet is not species-specific and can be extended to quantify additional ON characteristics in glaucoma and potentially other neurodegenerative diseases.
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Affiliation(s)
- Matthew D Ritch
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - Bailey G Hannon
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States
| | - A Thomas Read
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - Andrew J Feola
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, Georgia, United States
| | - Grant A Cull
- Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Juan Reynaud
- Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - John C Morrison
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Claude F Burgoyne
- Devers Eye Institute, Legacy Research Institute, Portland, Oregon, United States
| | - Machelle T Pardue
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
- Center for Visual and Neurocognitive Rehabilitation, Atlanta VA Healthcare System, Atlanta, Georgia, United States
| | - C Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States.
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia, United States.
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10
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Mysona BA, Segar S, Hernandez C, Kim C, Zhao J, Mysona D, Bollinger KE. QuPath Automated Analysis of Optic Nerve Degeneration in Brown Norway Rats. Transl Vis Sci Technol 2020; 9:22. [PMID: 32714648 PMCID: PMC7353320 DOI: 10.1167/tvst.9.3.22] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 12/11/2019] [Indexed: 01/03/2023] Open
Abstract
Purpose A novel application of QuPath open-source digital analysis software is used to provide in-depth morphological analysis of progressive optic nerve (ON) degeneration in rats. Methods QuPath software was adapted to assess axon and gliotic morphology in toluidine blue-stained, Brown Norway rat ON light micrographs. QuPath axon numbers, density, size distributions, and gliotic areas were obtained from test images and ON cross-sections separated by damage grade. QuPath results were compared with manual counting, AxonJ, and electron microscopy axon estimates. Results QuPath-derived axon number, density, and diameter decreased with increasing ON damage. Axon density negatively correlated with gliotic areas in test images (R2 = 0.759; P < 0.0001; N = 40) and in ON cross-sections (R2 = 0.803; P < 0.0004; N = 10). Although axon losses occurred across most axon diameters, large axons were more susceptible to degeneration. The exception was swollen axons > 2 µm, which increased in moderately but not severely damaged images. QuPath axon counts correlated strongly with manual counts of test images (R2 = 0.956; P < 0.0001). QuPath outperformed AxonJ on test images and total ON axon counts. Compared to electron microscopy analysis, QuPath undercounted ON axons; however, correlation between the methods was robust (R2 = 0.797; P < 0.001; N = 10). Conclusions QuPath analysis reliably identified axon loss, axon morphology changes, and gliotic expansion that occurred in degenerating ONs. Translational Relevance QuPath is a valuable tool for rapid, automated, analysis of healthy and degenerating ONs. Reproducible preclinical studies for new glaucoma treatments depend on unbiased in-depth analysis of ON pathology. This was provided by the QuPath approach.
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Affiliation(s)
- Barbara A. Mysona
- Department of Cellular Biology and Anatomy, Medical College of Georgia at Augusta University, Augusta, GA, USA
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Sharmila Segar
- Medical College of Georgia at Augusta University, Augusta, GA, USA
| | | | - Christian Kim
- Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Jing Zhao
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia at Augusta University, Augusta, GA, USA
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - David Mysona
- Medical College of Georgia at Augusta University, Augusta, GA, USA
| | - Kathryn E. Bollinger
- James and Jean Culver Vision Discovery Institute, Medical College of Georgia at Augusta University, Augusta, GA, USA
- Department of Ophthalmology, Medical College of Georgia at Augusta University, Augusta, GA, USA
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11
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Experimental glaucoma model with controllable intraocular pressure history. Sci Rep 2020; 10:126. [PMID: 31924837 PMCID: PMC6954231 DOI: 10.1038/s41598-019-57022-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 12/18/2019] [Indexed: 12/20/2022] Open
Abstract
Glaucoma-like neuropathies can be experimentally induced by disturbing aqueous outflow from the eye, resulting in intraocular pressure (IOP) changes that are variable in magnitude and time course and permanent in duration. This study introduces a novel method of glaucoma induction that offers researchers round-the-clock measurement and reversible control of IOP for the first time. One eye of Brown-Norway rats was implanted with a cannula tethered to a pressure sensor and aqueous reservoir. IOP was raised 10 mmHg for weeks-to-months in treated animals and unaltered in control animals. Counts of Brn3a-expressing retinal ganglion cells (RGCs) in implanted eyes were indistinguishable from non-implanted eyes in control animals and 15 ± 2%, 23 ± 4%, and 38 ± 4% lower in animals exposed to 2, 4, and 9 weeks of IOP elevation. RGC loss was greater in peripheral retina at 2 weeks and widespread at longer durations. Optic nerves also showed progressive degeneration with exposure duration, yet conventional outflow facility of implanted eyes was normal (24.1 ± 2.9 nl/min/mmHg) even after 9-weeks elevation. Hence, this infusion-based glaucoma model exhibits graded neural damage with unimpaired outflow pathways. The model further revealed a potentially-significant finding that outflow properties of rat eyes do not remodel in response to chronic ocular hypertension.
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12
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Koschade SE, Koch MA, Braunger BM, Tamm ER. Efficient determination of axon number in the optic nerve: A stereological approach. Exp Eye Res 2019; 186:107710. [PMID: 31254512 DOI: 10.1016/j.exer.2019.107710] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Revised: 05/26/2019] [Accepted: 06/21/2019] [Indexed: 11/26/2022]
Abstract
Quantifying the number of axons in the optic nerve is of interest in many research questions. Here, we show that a stereological method allows simple, efficient, precise and unbiased determination of the total axon number in the murine optic nerve. Axons in semi-thin optic nerve cross sections from untreated eyes (n = 21) and eyes subjected to retinal damage by intravitreous NMDA injections (n = 32) or PBS controls (n = 5) were manually identified, counted and digitally labeled by hand. A stereological procedure was empirically tested with systematic combinations of different sampling methods (simple random sampling without replacement, systematic uniform random sampling, stratified random sampling) and sampling parameters. Extensive numerical Monte Carlo experiments were performed to evaluate their large-sample properties. Our results demonstrate reliable determination of total axon number and superior performance compared to other methods at a small fraction of the time required for a full manual count. We specify suitable sampling parameters for the adoption of an efficient stereological sampling scheme, give empirical estimates of the additionally introduced sampling variance to facilitate experimental planning, and offer AxonCounter, an easy-to-use plugin implementing these stereological methods for the multi-platform image processing application NIH ImageJ.
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Affiliation(s)
- Sebastian E Koschade
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany.
| | - Marcus A Koch
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Barbara M Braunger
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany; Institute of Anatomy and Cell Biology, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Ernst R Tamm
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany.
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13
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Castelli V, Benedetti E, Antonosante A, Catanesi M, Pitari G, Ippoliti R, Cimini A, d'Angelo M. Neuronal Cells Rearrangement During Aging and Neurodegenerative Disease: Metabolism, Oxidative Stress and Organelles Dynamic. Front Mol Neurosci 2019; 12:132. [PMID: 31191244 PMCID: PMC6546816 DOI: 10.3389/fnmol.2019.00132] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 05/07/2019] [Indexed: 12/22/2022] Open
Abstract
Brain cells normally respond adaptively to oxidative stress or bioenergetic challenges, resulting from ongoing activity in neuronal circuits. During aging and in neurodegenerative disorders, these mechanisms are compromised. In fact, neurons show unique age-related changes in functions and metabolism, resulting in greater susceptibility to insults and disease. Aging affects the nervous system as well as other organs. More precisely, as the nervous system ages, neuron metabolism may change, inducing glucose hypometabolism, impaired transport of critical substrates underlying metabolism, alterations in calcium signaling, and mitochondrial dysfunction. Moreover, in neuronal aging, an accumulation of impaired and aggregated proteins in the cytoplasm and in mitochondria is observed, as the result of oxidative stress: reduced antioxidant defenses and/or increase of reactive oxygen species (ROS). These changes lead to greater vulnerability of neurons in various regions of the brain and increased susceptibility to several diseases. Specifically, the first part of the review article will focus on the major neuronal cells’ rearrangements during aging in response to changes in metabolism and oxidative stress, while the second part will cover the neurodegenerative disease areas in detail.
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Affiliation(s)
- Vanessa Castelli
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Abruzzo, Italy
| | - Elisabetta Benedetti
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Abruzzo, Italy
| | - Andrea Antonosante
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Abruzzo, Italy
| | - Mariano Catanesi
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Abruzzo, Italy
| | - Giuseppina Pitari
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Abruzzo, Italy
| | - Rodolfo Ippoliti
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Abruzzo, Italy
| | - Annamaria Cimini
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Abruzzo, Italy.,Sbarro Institute for Cancer Research and Molecular Medicine, Department of Biology, Temple University, Philadelphia, PA, United States
| | - Michele d'Angelo
- Department of Life, Health and Environmental Sciences, University of L'Aquila, Abruzzo, Italy
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14
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Zhu Y, Pappas AC, Wang R, Seifert P, Sun D, Jakobs TC. Ultrastructural Morphology of the Optic Nerve Head in Aged and Glaucomatous Mice. Invest Ophthalmol Vis Sci 2019; 59:3984-3996. [PMID: 30098187 PMCID: PMC6082327 DOI: 10.1167/iovs.18-23885] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Purpose To study age- and intraocular pressure–induced changes in the glial lamina of the murine optic nerve on the ultrastructural level. Methods Naïve C57bl/6 mice at various ages spanning the time between early adulthood (3 months) and senescence (30 months) were used in this study. In addition, the intraocular pressure (IOP) was increased in a group of young mice by injection of microbeads into the anterior chamber. The unmyelinated segments of the optic nerve containing the glial lamina were prepared for transmission electron microscopy and imaged at high resolution. Results Axon packing density decreased slightly with age. Aging nerves contained higher numbers of enlarged and degenerating axons. Mean axonal diameter and in particular the variance of axonal diameter correlated well with age. Axonal mitochondria also showed age-dependent signs of pathology. The mean diameter of axonal mitochondria increased, and aged axons often contained profiles of mitochondria with very few or no cristae. Astrocytic mitochondria remained normal even in very old nerves. Changes to axons and axonal mitochondria in young glaucomatous nerves were comparable with those of 18- to 30-month-old naïve mice. In addition to axons and mitochondria, aged and glaucomatous nerves showed thickening of the blood vessel basement membranes and increased deposition of basement membrane collagen. Conclusions On the ultrastructural level, the effects of age and elevated IOP are quite similar. One month of elevated IOP seems to have as strongly detrimental effects on the nerve as at least 18 months of normal aging.
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Affiliation(s)
- Ying Zhu
- Department of Ophthalmology, Tongji Hospital, Huazhong University of Science and Technology, Wuhan, Hubei, China.,Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States
| | - Anthony C Pappas
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States
| | - Rui Wang
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States.,Department of Ophthalmology, The First Hospital of Xi'an, Xi'an, Shaanxi, China
| | - Philip Seifert
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States
| | - Daniel Sun
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States
| | - Tatjana C Jakobs
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, Boston Massachusetts, United States
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15
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Identifying central and peripheral nerve fibres with an artificial intelligence approach. Appl Soft Comput 2018. [DOI: 10.1016/j.asoc.2018.03.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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16
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Nadal-Nicolás FM, Vidal-Sanz M, Agudo-Barriuso M. The aging rat retina: from function to anatomy. Neurobiol Aging 2017; 61:146-168. [PMID: 29080498 DOI: 10.1016/j.neurobiolaging.2017.09.021] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 09/19/2017] [Accepted: 09/20/2017] [Indexed: 01/13/2023]
Abstract
In healthy beings, age is the ultimate reason of cellular malfunction and death. In the rat retina, age causes a functional decline and loss of specific neuronal populations. In this regard, controversial conclusions have been reported for the innermost retina. Here, we have studied the albino and pigmented retina for the duration of the rat life-span. Independent of age (21 days-22 months), the electroretinographic recordings and the volume of the retina and its layers are smaller in albinos. Functionally, aging causes in both strains a loss of cone- and rod-mediated responses. Anatomically, cell density decreases with age because the retina grows linearly with time; no cell loss is observed in the ganglion cell layer; and only in the pigmented rat, there is a decrease in cone photoreceptors. In old animals of both strains, there is gliosis in the superior colliculi and a diminution of the area innervated by retinal ganglion cells. In conclusion, this work provides the basis for further studies linking senescence to neurodegenerative retinal diseases.
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Affiliation(s)
- Francisco M Nadal-Nicolás
- Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca) and Departamento de Oftalmología Facultad de Medicina, Universidad de Murcia, Murcia, Spain.
| | - Manuel Vidal-Sanz
- Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca) and Departamento de Oftalmología Facultad de Medicina, Universidad de Murcia, Murcia, Spain
| | - Marta Agudo-Barriuso
- Instituto Murciano de Investigación Biosanitaria-Virgen de la Arrixaca (IMIB-Arrixaca) and Departamento de Oftalmología Facultad de Medicina, Universidad de Murcia, Murcia, Spain.
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17
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Morrison JC, Cepurna WO, Tehrani S, Choe TE, Jayaram H, Lozano DC, Fortune B, Johnson EC. A Period of Controlled Elevation of IOP (CEI) Produces the Specific Gene Expression Responses and Focal Injury Pattern of Experimental Rat Glaucoma. Invest Ophthalmol Vis Sci 2017; 57:6700-6711. [PMID: 27942722 PMCID: PMC5156512 DOI: 10.1167/iovs.16-20573] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose We determine if several hours of controlled elevation of IOP (CEI) will produce the optic nerve head (ONH) gene expression changes and optic nerve (ON) damage pattern associated with early experimental glaucoma in rats. Methods The anterior chambers of anesthetized rats were cannulated and connected to a reservoir to elevate IOP. Physiologic parameters were monitored. Following CEI at various recovery times, ON cross-sections were graded for axonal injury. Anterior ONHs were collected at 0 hours to 10 days following CEI and RNA extracted for quantitative PCR measurement of selected messages. The functional impact of CEI was assessed by electroretinography (ERG). Results During CEI, mean arterial pressure (99 ± 6 mm Hg) and other physiologic parameters remained stable. An 8-hour CEI at 60 mm Hg produced significant focal axonal degeneration 10 days after exposure, with superior lesions in 83% of ON. Message analysis in CEI ONH demonstrated expression responses previously identified in minimally injured ONH following chronic IOP elevation, as well as their sequential patterns. Anesthesia with cannulation at 20 mm Hg did not alter these message levels. Electroretinographic A- and B-waves, following a significant reduction at 2 days after CEI, were fully recovered at 2 weeks, while peak scotopic threshold response (pSTR) remained mildly but significantly depressed. Conclusions A single CEI reproduces ONH message changes and patterns of ON injury previously observed with chronic IOP elevation. Controlled elevation of IOP can allow detailed determination of ONH cellular and functional responses to an injurious IOP insult and provide a platform for developing future therapeutic interventions.
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Affiliation(s)
- John C Morrison
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - William O Cepurna
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Shandiz Tehrani
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Tiffany E Choe
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Hari Jayaram
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States 2Glaucoma Service, NIHR Moorfields Biomedical Research Centre, London, United Kingdom
| | - Diana C Lozano
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
| | - Brad Fortune
- Devers Eye Institute, Portland, Oregon, United States
| | - Elaine C Johnson
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States
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18
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Grillo FW. Long live the axon. Parallels between ageing and pathology from a presynaptic point of view. J Chem Neuroanat 2015; 76:28-34. [PMID: 26698224 DOI: 10.1016/j.jchemneu.2015.12.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Accepted: 12/11/2015] [Indexed: 12/12/2022]
Abstract
All animals have to find the right balance between investing resources into their reproductive cycle and protecting their tissues from age-related damage. In higher order organisms the brain is particularly vulnerable to ageing, as the great majority of post-mitotic neurons are there to stay for an entire life. While ageing is unavoidable, it may progress at different rates in different individuals of the same species depending on a variety of genetic and environmental factors. Inevitably though, ageing results in a cognitive and sensory-motor decline caused by changes in neuronal structure and function. Besides normal ageing, age-related pathological conditions can develop in a sizeable proportion of the population. While this wide array of diseases are considerably different compared to physiological ageing, the two processes share many similarities and are likely to interact. At the subcellular level, two key structures are involved in brain ageing: axons and their synapses. Here I highlight how the ageing process affects these structures in normal and neurodegenerative states in different brain areas.
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Affiliation(s)
- Federico W Grillo
- MRC Centre for Developmental Neurobiology, Medical Research Council, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK.
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19
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Adalbert R, Coleman MP. Review: Axon pathology in age-related neurodegenerative disorders. Neuropathol Appl Neurobiol 2015; 39:90-108. [PMID: 23046254 DOI: 10.1111/j.1365-2990.2012.01308.x] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2012] [Accepted: 09/24/2012] [Indexed: 12/12/2022]
Abstract
'Dying back' axon degeneration is a prominent feature of many age-related neurodegenerative disorders and is widespread in normal ageing. Although the mechanisms of disease- and age-related losses may differ, both contribute to symptoms. Here, we review recent advances in understanding axon pathology in age-related neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and glaucoma. In particular, we highlight the importance of axonal transport, autophagy, traumatic brain injury and mitochondrial quality control. We then place these disease mechanisms in the context of changes to axons and dendrites that occur during normal ageing. We discuss what makes ageing such an important risk factor for many neurodegenerative disorders and conclude that the processes of normal ageing and disease combine at the molecular, cellular or systems levels in a range of disorders to produce symptoms. Pathology identical to disease also occurs at the cellular level in most elderly individuals. Thus, normal ageing and age-related disease are inextricably linked and the term 'healthy ageing' downplays the important contributions of cellular pathology. For a full understanding of normal ageing or age-related disease we must study both processes.
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Affiliation(s)
- R Adalbert
- Signalling Programme, The Babraham Institute, Babraham, Cambridge, UK
| | - M P Coleman
- Signalling Programme, The Babraham Institute, Babraham, Cambridge, UK
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20
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Pazos M, Yang H, Gardiner SK, Cepurna WO, Johnson EC, Morrison JC, Burgoyne CF. Expansions of the neurovascular scleral canal and contained optic nerve occur early in the hypertonic saline rat experimental glaucoma model. Exp Eye Res 2015; 145:173-186. [PMID: 26500195 DOI: 10.1016/j.exer.2015.10.014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/14/2015] [Accepted: 10/16/2015] [Indexed: 11/28/2022]
Abstract
PURPOSE To characterize early optic nerve head (ONH) structural change in rat experimental glaucoma (EG). METHODS Unilateral intraocular pressure (IOP) elevation was induced in Brown Norway rats by hypertonic saline injection into the episcleral veins and animals were sacrificed 4 weeks later by perfusion fixation. Optic nerve cross-sections were graded from 1 (normal) to 5 (extensive injury) by 5 masked observers. ONHs with peripapillary retina and sclera were embedded, serial sectioned, 3-D reconstructed, delineated, and quantified. Overall and animal-specific EG versus Control eye ONH parameter differences were assessed globally and regionally by linear mixed effect models with significance criteria adjusted for multiple comparisons. RESULTS Expansions of the optic nerve and surrounding anterior scleral canal opening achieved statistical significance overall (p < 0.0022), and in 7 of 8 EG eyes (p < 0.005). In at least 5 EG eyes, significant expansions (p < 0.005) in Bruch's membrane opening (BMO) (range 3-10%), the anterior and posterior scleral canal openings (8-21% and 5-21%, respectively), and the optic nerve at the anterior and posterior scleral canal openings (11-30% and 8-41%, respectively) were detected. Optic nerve expansion was greatest within the superior and inferior quadrants. Optic nerve expansion at the posterior scleral canal opening was significantly correlated to optic nerve damage (R = 0.768, p = 0.042). CONCLUSION In the rat ONH, the optic nerve and surrounding BMO and neurovascular scleral canal expand early in their response to chronic experimental IOP elevation. These findings provide phenotypic landmarks and imaging targets for detecting the development of experimental glaucomatous optic neuropathy in the rat eye.
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Affiliation(s)
- Marta Pazos
- Hospital de l'Esperança, Parc de Salut Mar, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Hongli Yang
- Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, USA
| | - Stuart K Gardiner
- Devers Eye Institute, Discoveries in Sight Research Laboratories, Legacy Research Institute, Portland, OR, USA
| | - William O Cepurna
- Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA
| | - Elaine C Johnson
- Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA
| | - John C Morrison
- Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, OR, USA
| | - Claude F Burgoyne
- Devers Eye Institute, Optic Nerve Head Research Laboratory, Legacy Research Institute, Portland, OR, USA.
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21
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The non-human primate experimental glaucoma model. Exp Eye Res 2015; 141:57-73. [PMID: 26070984 DOI: 10.1016/j.exer.2015.06.005] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 06/03/2015] [Accepted: 06/06/2015] [Indexed: 01/05/2023]
Abstract
The purpose of this report is to summarize the current strengths and weaknesses of the non-human primate (NHP) experimental glaucoma (EG) model through sections devoted to its history, methods, important findings, alternative optic neuropathy models and future directions. NHP EG has become well established for studying human glaucoma in part because the NHP optic nerve head (ONH) shares a close anatomic association with the human ONH and because it provides the only means of systematically studying the very earliest visual system responses to chronic intraocular pressure (IOP) elevation, i.e. the conversion from ocular hypertension to glaucomatous damage. However, NHPs are impractical for studies that require large animal numbers, demonstrate spontaneous glaucoma only rarely, do not currently provide a model of the neuropathy at normal levels of IOP, and cannot easily be genetically manipulated, except through tissue-specific, viral vectors. The goal of this summary is to direct NHP EG and non-NHP EG investigators to the previous, current and future accomplishment of clinically relevant knowledge in this model.
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Morrison JC, Cepurna WO, Johnson EC. Modeling glaucoma in rats by sclerosing aqueous outflow pathways to elevate intraocular pressure. Exp Eye Res 2015; 141:23-32. [PMID: 26003399 DOI: 10.1016/j.exer.2015.05.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Revised: 05/18/2015] [Accepted: 05/19/2015] [Indexed: 12/14/2022]
Abstract
Injection of hypertonic saline via episcleral veins toward the limbus in laboratory rats can produce elevated intraocular pressure (IOP) by sclerosis of aqueous humor outflow pathways. This article describes important anatomic characteristics of the rat optic nerve head (ONH) that make it an attractive animal model for human glaucoma, along with the anatomy of rat aqueous humor outflow on which this technique is based. The injection technique itself is also described, with the aid of a supplemental movie, including necessary equipment and specific tips to acquire this skill. Outcomes of a successful injection are presented, including IOP elevation and patterns of optic nerve injury. These concepts are then specifically considered in light of the use of this model to assess potential neuroprotective therapies. Advantages of the hypertonic saline model include a delayed and relatively gradual IOP elevation, likely reproduction of scleral and ONH stresses and strains that may be important in producing axonal injury, and its ability to be applied to any rat (and potentially mouse) strain, leaving the unmanipulated fellow eye as an internal control. Challenges include the demanding surgical skill required by the technique itself, a wide range of IOP response, and mild corneal clouding in some animals. However, meticulous application of the principles detailed in this article and practice will allow most researchers to attain this useful skill for studying cellular events of glaucomatous optic nerve damage.
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Affiliation(s)
- John C Morrison
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, USA.
| | - William O Cepurna
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, USA
| | - Elaine C Johnson
- The Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, USA
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Induction of autophagy in rats upon overexpression of wild-type and mutant optineurin gene. BMC Cell Biol 2015; 16:14. [PMID: 25943884 PMCID: PMC4429416 DOI: 10.1186/s12860-015-0060-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 04/22/2015] [Indexed: 12/31/2022] Open
Abstract
Background Optineurin is a gene associated with normal tension glaucoma and amyotrophic lateral sclerosis. It has been reported previously that in cultured RGC5 cells, the turnover of endogenous optineurin involves mainly the ubiquitin-proteasome pathway (UPP). When optineurin is upregulated or mutated, the UPP function is compromised as evidenced by a decreased proteasome β5 subunit (PSMB5) level and autophagy is induced for clearance of the optineurin protein. Results Adeno-associated type 2 viral (AAV2) vectors for green fluorescence protein (GFP) only, GFP-tagged wild-type and Glu50Lys (E50K) mutated optineurin were intravitreally injected into rats for expression in retinal ganglion cells (RGCs). Following intravitreal injections, eyes that received optineurin vectors exhibited retinal thinning, as well as RGC and axonal loss compared to GFP controls. By immunostaining and Western blotting, the level of PSMB5 and autophagic substrate degradation marker p62 was reduced, and the level of autophagic marker microtubule associated protein 1 light chain 3 (LC3) was enhanced. The UPP impairment and autophagy induction evidently occurred in vivo as in vitro. The optineurin level, RGC and axonal counts, and apoptosis in AAV2-E50K-GFP-injected rat eyes were averted to closer to normal limits after treatment with rapamycin, an autophagic enhancer. Conclusions The UPP function was reduced and autophagy was induced when wild-type and E50K optineurin was overexpressed in rat eyes. This study validates the in vitro findings, confirming that UPP impairment and autophagy induction also occur in vivo. In addition, rapamycin is demonstrated to clear the accumulated mutant optineurin. This agent may potentially be useful for rescuing of the adverse optineurin phenotypes in vivo.
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Biasibetti E, Bisanzio D, Mioletti S, Amedeo S, Iuliano A, Bianco P, Capucchio MT. Spontaneous Age-related Changes of Peripheral Nerves in Cattle: Morphological and Biochemical Studies. Anat Histol Embryol 2015; 45:100-8. [PMID: 25823666 DOI: 10.1111/ahe.12177] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 02/16/2015] [Indexed: 11/29/2022]
Abstract
Peripheral nerve function is significantly affected by ageing. During ageing process, multiple changes occur on tissue cells and extracellular matrix. The aim of this work was to study the ageing-associated changes of peripheral nerves in adult and old regularly slaughtered cattle compared with young calves, and correlate them to the features reported in humans and laboratory animals. Samples of axial dorsal metacarpal nerves from 44 cows were collected immediately after slaughtering. Each nerve was dissected and divided into two fragments: one used for morphological evaluation (n = 43) and the other one for biochemical analysis (n = 31). Axonal degeneration, demyelination, thickness of perineurium and endoneurium and increase of mast cells were the most important features detected. The mean amount of glycosaminoglycan quantitative content recorded in the samples increased with the age. Axonal degeneration, demyelination and thickness of endoneurium were positively and significantly correlated with biochemistry. The presence of changes affecting the different elements of the peripheral nerves, similar to that reported in humans and in laboratory species, the easy availability of the nerve tissue in this species, the considerable size of the samples and the life conditions more similar to humans than to laboratory animals, allows the authors to consider cattle as a potential good model for the comparative study of spontaneous ageing nerve lesions.
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Affiliation(s)
- E Biasibetti
- Department of Veterinary Sciences, University of Torino, Largo Braccini 2, 10095, Grugliasco, Torino, Italy
| | - D Bisanzio
- Department of Environmental Sciences, Emory University, 400 Dowman Drive, Atlanta, GA, 30322, USA
| | - S Mioletti
- Department of Veterinary Sciences, University of Torino, Largo Braccini 2, 10095, Grugliasco, Torino, Italy
| | - S Amedeo
- Department of Veterinary Sciences, University of Torino, Largo Braccini 2, 10095, Grugliasco, Torino, Italy
| | - A Iuliano
- Department of Veterinary Sciences, University of Torino, Largo Braccini 2, 10095, Grugliasco, Torino, Italy
| | - P Bianco
- ASLTo4, via Po 11, 10034, Chivasso, Torino, Italy
| | - M T Capucchio
- Department of Veterinary Sciences, University of Torino, Largo Braccini 2, 10095, Grugliasco, Torino, Italy
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25
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Autophagy in axonal degeneration in glaucomatous optic neuropathy. Prog Retin Eye Res 2015; 47:1-18. [PMID: 25816798 DOI: 10.1016/j.preteyeres.2015.03.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 03/14/2015] [Accepted: 03/19/2015] [Indexed: 01/07/2023]
Abstract
The role of autophagy in retinal ganglion cell (RGC) death is still controversial. Several studies focused on RGC body death, although the axonal degeneration pathway in the optic nerve has not been well documented in spite of evidence that the mechanisms of degeneration of neuronal cell bodies and their axons differ. Axonal degeneration of RGCs is a hallmark of glaucoma, and a pattern of localized retinal nerve fiber layer defects in glaucoma patients indicates that axonal degeneration may precede RGC body death in this condition. As models of preceding axonal degeneration, both the tumor necrosis factor (TNF) injection model and hypertensive glaucoma model may be useful in understanding the mechanism of axonal degeneration of RGCs, and the concept of axonal protection can be an attractive approach to the prevention of neurodegenerative optic nerve disease. Since mitochondria play crucial roles in glaucomatous optic neuropathy and can themselves serve as a part of the autophagosome, it seems that mitochondrial function may alter autophagy machinery. Like other neurodegenerative diseases, optic nerve degeneration may exhibit autophagic flux impairment resulting from elevated intraocular pressure, TNF, traumatic injury, ischemia, oxidative stress, and aging. As a model of aging, we used senescence-accelerated mice to provide new insights. In this review, we attempt to describe the relationship between autophagy and recently reported noteworthy factors including Nmnat, ROCK, and SIRT1 in the degeneration of RGCs and their axons and propose possible mechanisms of axonal protection via modulation of autophagy machinery.
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Kim CY, Rho S, Lee N, Lee CK, Sung Y. Semi-automated counting method of axons in transmission electron microscopic images. Vet Ophthalmol 2015; 19:29-37. [PMID: 25639186 DOI: 10.1111/vop.12247] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To evaluate the accuracy of a new semi-automated method for counting axons in transmission electron microscopic (TEM) images. PROCEDURES Optic nerve cross sections were obtained from both eyes of Sprague Dawley rats after unilateral induction of chronic ocular hypertension. TEM images (3000× magnification) of cross sections were evaluated by both semi-automated and manual counting methods. The semi-automated counting method was performed using ImageJ software after simple image optimization, and the resulting estimate of axon damage was compared with semiquantitative damage grading scale from light microscopic (LM) images. RESULTS Axon counts obtained from the semi-automated method were strongly correlated with those obtained from the manual counting method (Pearson's correlation coefficient r = 0.996, P < 0.001) and from the full manual count from LM images (Spearman's ρ = 0.973, P < 0.001). The semi-automated method measured axonal damage with an error of 0.94 ± 3.16% (mean ± standard deviation), with worse axonal damage associated with greater error. Interobserver and intra-observer variability in axons counts were low (Spearman's ρ = 0.999, P < 0.005). The results of the semi-automated counting method were highly correlated with semiquantitative damage grading scale (Spearman's ρ = 0.965, P < 0.001). CONCLUSION Results of our semi-automated method for counting axons in TEM images were strongly correlated with those of conventional counting methods and showed excellent reproducibility.
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Affiliation(s)
- Chan Yun Kim
- Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
| | - Seungsoo Rho
- Department of Ophthalmology, CHA Bundang Medical Center, CHA University, 59 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-712, Korea
| | - Naeun Lee
- Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
| | - Chang-Kyu Lee
- Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, Korea
| | - Youngje Sung
- Department of Ophthalmology, CHA Bundang Medical Center, CHA University, 59 Yatap-ro, Bundang-gu, Seongnam-si, Gyeonggi-do, 463-712, Korea
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Abbott CJ, Choe TE, Burgoyne CF, Cull G, Wang L, Fortune B. Comparison of retinal nerve fiber layer thickness in vivo and axonal transport after chronic intraocular pressure elevation in young versus older rats. PLoS One 2014; 9:e114546. [PMID: 25501362 PMCID: PMC4263742 DOI: 10.1371/journal.pone.0114546] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2014] [Accepted: 11/11/2014] [Indexed: 12/28/2022] Open
Abstract
PURPOSE To compare in young and old rats longitudinal measurements of retinal nerve fiber layer thickness (RNFLT) and axonal transport 3-weeks after chronic IOP elevation. METHOD IOP was elevated unilaterally in 2- and 9.5-month-old Brown-Norway rats by intracameral injections of magnetic microbeads. RNFLT was measured by spectral domain optical coherence tomography. Anterograde axonal transport was assessed from confocal scanning laser ophthalmolscopy of superior colliculi (SC) after bilateral intravitreal injections of cholera toxin-B-488. Optic nerve sections were graded for damage. RESULTS Mean IOP was elevated in both groups (young 37, old 38 mmHg, p = 0.95). RNFL in young rats exhibited 10% thickening at 1-week (50.9±8.1 µm, p<0.05) vs. baseline (46.4±2.4 µm), then 7% thinning at 2-weeks (43.0±7.2 µm, p>0.05) and 3-weeks (43.5±4.4 µm, p>0.05), representing 20% loss of dynamic range. RNFLT in old rats showed no significant change at 1-week (44.9±4.1 µm) vs. baseline (49.2±5.3 µm), but progression to 22% thinning at 2-weeks (38.0±3.7 µm, p<0.01) and 3-weeks (40.0±6.6 µm, p<0.05), representing 59% loss of dynamic range. Relative SC fluorescence intensity was reduced in both groups (p<0.001), representing 77-80% loss of dynamic range and a severe transport deficit. Optic nerves showed 75-95% damage (p<0.001). There was greater RNFL thinning in old rats (p<0.05), despite equivalent IOP insult, transport deficit and nerve damage between age groups (all p>0.05). CONCLUSION Chronic IOP elevation resulted in severely disrupted axonal transport and optic nerve axon damage in all rats, associated with mild RNFL loss in young rats but a moderate RNFL loss in old rats despite the similar IOP insult. Hence, the glaucomatous injury response within the RNFL depends on age.
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Affiliation(s)
- Carla J. Abbott
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Tiffany E. Choe
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Claude F. Burgoyne
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Grant Cull
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Lin Wang
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
| | - Brad Fortune
- Discoveries in Sight Research Laboratories, Devers Eye Institute and Legacy Research Institute, Legacy Health, Portland, Oregon, United States of America
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Yassa HD. Age-related changes in the optic nerve of Sprague-Dawley rats: an ultrastructural and immunohistochemical study. Acta Histochem 2014; 116:1085-95. [PMID: 24958340 DOI: 10.1016/j.acthis.2014.05.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Revised: 05/04/2014] [Accepted: 05/13/2014] [Indexed: 01/11/2023]
Abstract
The optic nerve is a unique part of the central nervous system. It lacks neuronal cell bodies and consists of axons of the retinal ganglion cells together with the supporting neuroglial cells. In the present study, aging of the optic nerve was studied in female Sprague-Dawley rats aged 3, 12, 24 and 30 months old, ultrastructurally, immunohistochemically and morphometrically trying to answer the question why aging is a common risk factor for many ocular diseases especially glaucoma. Additionally, studying the optic nerve aging offered a good opportunity to gain further insight into the effects of aging on white matter. Both nerve fibers and neuroglial cells demonstrated several age related changes which were more profound in 30 months old rats. Optic nerve axons displayed watery degeneration and dark degeneration. Myelin disturbances including widening, whorls, splitting and vacuolations of the myelin lamellae were also observed. Neuroglial cells appeared to be more frequent than in younger rats especially microglia cells and developed dense cytoplasmic inclusions. GFAP-positive astrocytes delineated age-related progressive increase in number, size as well as length and thickness of their processes. CD68 immunohistochemical staining revealed age-related changes in the morphology, location and number of CD68 positive microglia cells.
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Affiliation(s)
- Hanan Dawood Yassa
- Department of Anatomy and Embryology, Faculty of Medicine, Beni Suef University, Salah Salem St., 62511 Beni Suef, Egypt.
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29
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Yan Y, Li L, Preuss TM, Hu X, Herndon JG, Zhang X. In vivo evaluation of optic nerve aging in adult rhesus monkey by diffusion tensor imaging. Quant Imaging Med Surg 2014; 4:43-9. [PMID: 24649434 DOI: 10.3978/j.issn.2223-4292.2014.02.04] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 02/17/2014] [Indexed: 01/14/2023]
Abstract
Aging of the optic nerve can result in reduced visual sensitivity or vision loss. Normal optic nerve aging has been investigated previously in tissue specimens but poorly explored in vivo. In the present study, the normal aging of optic nerve was evaluated by diffusion tensor imaging (DTI) in non-human primates. Adult female rhesus monkeys at the ages of 9 to 13 years old (young group, n=8) and 21 to 27 years old (old group, n=7) were studied using parallel-imaging-based DTI on a clinical 3T scanner. Compared to young adults, the old monkeys showed 26% lower fractional anisotropy (P<0.01), and 44% greater radial diffusivity, although the latter difference was of marginal statistical significance (P=0.058). These MRI findings are largely consistent with published results of light and electron microscopic studies of optic nerve aging in macaque monkeys, which indicate a loss of fibers and degenerative changes in myelin sheaths.
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Affiliation(s)
- Yumei Yan
- 1 Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 2 Marcus Autism Center, Children's Healthcare of Atlanta, Emory University, Atlanta, Georgia 30322, USA ; 3 Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 4 The Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia 30322, USA
| | - Longchuan Li
- 1 Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 2 Marcus Autism Center, Children's Healthcare of Atlanta, Emory University, Atlanta, Georgia 30322, USA ; 3 Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 4 The Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia 30322, USA
| | - Todd M Preuss
- 1 Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 2 Marcus Autism Center, Children's Healthcare of Atlanta, Emory University, Atlanta, Georgia 30322, USA ; 3 Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 4 The Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia 30322, USA
| | - Xiaoping Hu
- 1 Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 2 Marcus Autism Center, Children's Healthcare of Atlanta, Emory University, Atlanta, Georgia 30322, USA ; 3 Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 4 The Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia 30322, USA
| | - James G Herndon
- 1 Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 2 Marcus Autism Center, Children's Healthcare of Atlanta, Emory University, Atlanta, Georgia 30322, USA ; 3 Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 4 The Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia 30322, USA
| | - Xiaodong Zhang
- 1 Yerkes Imaging Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 2 Marcus Autism Center, Children's Healthcare of Atlanta, Emory University, Atlanta, Georgia 30322, USA ; 3 Division of Neuropharmacology and Neurologic Diseases, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia 30329, USA ; 4 The Wallace H. Coulter Department of Biomedical Engineering, Emory University and Georgia Institute of Technology, Atlanta, Georgia 30322, USA
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30
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Abbott CJ, Choe TE, Lusardi TA, Burgoyne CF, Wang L, Fortune B. Evaluation of retinal nerve fiber layer thickness and axonal transport 1 and 2 weeks after 8 hours of acute intraocular pressure elevation in rats. Invest Ophthalmol Vis Sci 2014; 55:674-87. [PMID: 24398096 DOI: 10.1167/iovs.13-12811] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
PURPOSE To compare in vivo retinal nerve fiber layer thickness (RNFLT) and axonal transport at 1 and 2 weeks after an 8-hour acute IOP elevation in rats. METHODS Forty-seven adult male Brown Norway rats were used. Procedures were performed under anesthesia. The IOP was manometrically elevated to 50 mm Hg or held at 15 mm Hg (sham) for 8 hours unilaterally. The RNFLT was measured by spectral-domain optical coherence tomography. Anterograde and retrograde axonal transport was assessed from confocal scanning laser ophthalmoscopy imaging 24 hours after bilateral injections of 2 μL 1% cholera toxin B-subunit conjugated to AlexaFluor 488 into the vitreous or superior colliculi, respectively. Retinal ganglion cell (RGC) and microglial densities were determined using antibodies against Brn3a and Iba-1. RESULTS The RNFLT in experimental eyes increased from baseline by 11% at 1 day (P < 0.001), peaked at 19% at 1 week (P < 0.0001), remained 11% thicker at 2 weeks (P < 0.001), recovered at 3 weeks (P > 0.05), and showed no sign of thinning at 6 weeks (P > 0.05). There was no disruption of anterograde transport at 1 week (superior colliculi fluorescence intensity, 75.3 ± 7.9 arbitrary units [AU] for the experimental eyes and 77.1 ± 6.7 AU for the control eyes) (P = 0.438) or 2 weeks (P = 0.188). There was no obstruction of retrograde transport at 1 week (RCG density, 1651 ± 153 per mm(2) for the experimental eyes and 1615 ± 135 per mm(2) for the control eyes) (P = 0.63) or 2 weeks (P = 0.25). There was no loss of Brn3a-positive RGC density at 6 weeks (P = 0.74) and no increase in microglial density (P = 0.92). CONCLUSIONS Acute IOP elevation to 50 mm Hg for 8 hours does not cause a persisting axonal transport deficit at 1 or 2 weeks or a detectable RNFLT or RGC loss by 6 weeks but does lead to transient RNFL thickening that resolves by 3 weeks.
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Affiliation(s)
- Carla J Abbott
- Discoveries in Sight Research Laboratories, Legacy Good Samaritan Devers Eye Institute, and Legacy Research Institute, Legacy Health, Portland, Oregon
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31
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Steinhart MR, Cone-Kimball E, Nguyen C, Nguyen TD, Pease ME, Chakravarti S, Oglesby EN, Quigley HA. Susceptibility to glaucoma damage related to age and connective tissue mutations in mice. Exp Eye Res 2013; 119:54-60. [PMID: 24368172 DOI: 10.1016/j.exer.2013.12.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 11/14/2013] [Accepted: 12/13/2013] [Indexed: 12/16/2022]
Abstract
The purpose of this research was to study the effects of age and genetic alterations in key connective tissue proteins on susceptibility to experimental glaucoma in mice. We used mice haploinsufficient in the elastin gene (EH) and mice without both alleles of the fibromodulin gene (FM KO) and their wild type (WT) littermates of B6 and CD1 strains, respectively. FM KO mice were tested at two ages: 2 months and 12 months. Intraocular pressure (IOP) was measured by Tonolab tonometer, axial lengths and widths measured by digital caliper post-enucleation, and chronic glaucoma damage was measured using a bead injection model and optic nerve axon counts. IOP in EH mice was not significantly different from WT, but FM KO were slightly lower than their controls (p = 0.04). Loss of retinal ganglion cell (RGC) axons was somewhat, but not significantly greater in young EH and younger or older FM KO strains than in age-matched controls (p = 0.48, 0.34, 0.20, respectively, multivariable regression adjusting for IOP exposure). Older CD1 mice lost significantly more RGC axons than younger CD1 (p = 0.01, multivariable regression). The CD1 mouse strain showed age-dependence of experimental glaucoma damage to RGC in the opposite, and more expected, direction than in B6 mice in which older mice are more resistant to damage. Genetic alteration in two genes that are constituents of sclera, fibromodulin and elastin do not significantly affect RGC loss.
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Affiliation(s)
- Matthew R Steinhart
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Elizabeth Cone-Kimball
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Cathy Nguyen
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Thao D Nguyen
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Mechanical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Mary E Pease
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Shukti Chakravarti
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Ericka N Oglesby
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Harry A Quigley
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States.
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Calkins DJ. Age-related changes in the visual pathways: blame it on the axon. Invest Ophthalmol Vis Sci 2013; 54:ORSF37-41. [PMID: 24335066 DOI: 10.1167/iovs.13-12784] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The aging visual system is marked by a decline in some, but not all, key functions. Some of this decline is attributed to changes in the optics of the eye, but other aspects must have a neural basis. Across mammals, with aging there is remarkable persistence of central structures to which retinal ganglion cell (RGC) axons project with little or no loss of neurons. Similarly, RGC bodies in the retina are subject to variable age-related loss, with most mammals showing none over time. In contrast, the RGC axon itself is highly vulnerable. Across species, the rate of axon loss in the optic nerve is related inversely to the total number of axons at maturity and lifespan. The result of this scaling is approximately a 40% total decline in axon number. Evidence suggests that the consistent vulnerability of RGC axons to aging arises from their high metabolic demand combined with diminishing resources. Thus, therapeutic interventions that conserve bioenergetics may have potential to abate age-related decline in visual function.
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Affiliation(s)
- David J Calkins
- The Vanderbilt Eye Institute and Vanderbilt Brain Institute, Vanderbilt University Medical Center, Nashville, Tennessee
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33
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The fatty acid amide hydrolase inhibitor, URB597, promotes retinal ganglion cell neuroprotection in a rat model of optic nerve axotomy. Neuropharmacology 2013; 72:116-25. [DOI: 10.1016/j.neuropharm.2013.04.018] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2012] [Revised: 04/11/2013] [Accepted: 04/12/2013] [Indexed: 11/19/2022]
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34
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Reynaud J, Cull G, Wang L, Fortune B, Gardiner S, Burgoyne CF, Cioffi GA. Automated quantification of optic nerve axons in primate glaucomatous and normal eyes--method and comparison to semi-automated manual quantification. Invest Ophthalmol Vis Sci 2012; 53:2951-9. [PMID: 22467571 DOI: 10.1167/iovs.11-9274] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To describe an algorithm and software application (APP) for 100% optic nerve axon counting and to compare its performance with a semi-automated manual (SAM) method in optic nerve cross-section images (images) from normal and experimental glaucoma (EG) nonhuman primate (NHP) eyes. METHODS ON cross sections from eight EG eyes from eight NHPs, five EG and five normal eyes from five NHPs, and 12 normal eyes from 12 NHPs were imaged at 100×. Calibration (n = 500) and validation (n = 50) image sets ranging from normal to end-stage damage were assembled. Correlation between APP and SAM axon counts was assessed by Deming regression within the calibration set and a compensation formula was generated to account for the subtle, systematic differences. Then, compensated APP counts for each validation image were compared with the mean and 95% confidence interval of five SAM counts of the validation set performed by a single observer. RESULTS Calibration set APP counts linearly correlated to SAM counts (APP = 10.77 + 1.03 [SAM]; R(2) = 0.94, P < 0.0001) in normal to end-stage damage images. In the validation set, compensated APP counts fell within the 95% confidence interval of the SAM counts in 42 of the 50 images and were within 12 axons of the confidence intervals in six of the eight remaining images. Uncompensated axon density maps for the normal and EG eyes of a representative NHP were generated. CONCLUSIONS An APP for 100% ON axon counts has been calibrated and validated relative to SAM counts in normal and EG NHP eyes.
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Affiliation(s)
- Juan Reynaud
- Devers Eye Institute, Legacy Health System, Portland, Oregon 97232, USA
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The molecular basis of retinal ganglion cell death in glaucoma. Prog Retin Eye Res 2012; 31:152-81. [DOI: 10.1016/j.preteyeres.2011.11.002] [Citation(s) in RCA: 565] [Impact Index Per Article: 47.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 10/28/2011] [Accepted: 11/01/2011] [Indexed: 12/14/2022]
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Burgoyne CF. A biomechanical paradigm for axonal insult within the optic nerve head in aging and glaucoma. Exp Eye Res 2011; 93:120-32. [PMID: 20849846 PMCID: PMC3128181 DOI: 10.1016/j.exer.2010.09.005] [Citation(s) in RCA: 276] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Revised: 09/04/2010] [Accepted: 09/07/2010] [Indexed: 12/27/2022]
Abstract
This article is dedicated to Rosario Hernandez for her warm support of my own work and her genuine enthusiasm for the work of her colleagues throughout her career. I first met Rosario as a research fellow in Harry Quigley's laboratory between 1991 and 1993. Along with Harry, John Morrison, Elaine Johnson, Abe Clark, Colm O'Brien and many others, Rosario's work has provided lamina cribrosa astrocyte cellular mechanisms that are biomechanically plausible and in so doing provided credibility to early notions of the optic nerve head (ONH) as a biomechanical structure. We owe a large intellectual debt to Rosario for her dogged persistence in the characterization of the ONH astrocyte and lamina cribrosacyte in age and disease. Two questions run through her work and remain of central importance today. First, how do astrocytes respond to and alter the biomechanical environment of the ONH and the physiologic stresses created therein? Second, how do these physiologic demands on the astrocyte influence their ability to deliver the support to retinal ganglion cell axon transport and flow against the translaminar pressure gradient? The purpose of this article is to summarize what is known about the biomechanical determinants of retinal ganglion cell axon physiology within the ONH in the optic neuropathy of aging and Glaucoma. My goal is to provide a biomechanical framework for this discussion. This framework assumes that the ONH astrocytes and glia fundamentally support and influence both the lamina cribrosa extracellular matrix and retinal ganglion cell axon physiology. Rosario Hernandez was one of the first investigators to recognize the implications of this unique circumstance. Many of the ideas contained herein have been initially presented within or derived from her work (Hernandez, M.R., 2000. The optic nerve head in glaucoma: role of astrocytes in tissue remodeling. Prog Retin Eye Res. 19, 297-321.; Hernandez, M.R., Pena, J.D., 1997. The optic nerve head in glaucomatous optic neuropathy. Arch Ophthalmol. 115, 389-395.).
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Affiliation(s)
- Claude F Burgoyne
- Optic Nerve Head Research Laboratory, Part of the Discoveries in Sight Research Laboratories of the Devers Eye Institute, Legacy Health System, 1225 NE 2nd Ave, Portland, OR 97232, USA.
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Morphological changes in nerve cells during normal aging. Brain Struct Funct 2011; 216:85-9. [PMID: 21431333 DOI: 10.1007/s00429-011-0308-y] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Accepted: 03/04/2011] [Indexed: 10/18/2022]
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Johnson EC, Doser TA, Cepurna WO, Dyck JA, Jia L, Guo Y, Lambert WS, Morrison JC. Cell proliferation and interleukin-6-type cytokine signaling are implicated by gene expression responses in early optic nerve head injury in rat glaucoma. Invest Ophthalmol Vis Sci 2011; 52:504-18. [PMID: 20847120 DOI: 10.1167/iovs.10-5317] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
PURPOSE In glaucoma, the optic nerve head (ONH) is the principal site of initial axonal injury, and elevated intraocular pressure (IOP) is the predominant risk factor. However, the initial responses of the ONH to elevated IOP are unknown. Here the authors use a rat glaucoma model to characterize ONH gene expression changes associated with early optic nerve injury. METHODS Unilateral IOP elevation was produced in rats by episcleral vein injection of hypertonic saline. ONH mRNA was extracted, and retrobulbar optic nerve cross-sections were graded for axonal degeneration. Gene expression was determined by microarray and quantitative PCR (QPCR) analysis. Significantly altered gene expression was determined by multiclass analysis and ANOVA. DAVID gene ontology determined the functional categories of significantly affected genes. RESULTS The Early Injury group consisted of ONH from eyes with <15% axon degeneration. By array analysis, 877 genes were significantly regulated in this group. The most significant upregulated gene categories were cell cycle, cytoskeleton, and immune system process, whereas the downregulated categories included glucose and lipid metabolism. QPCR confirmed the upregulation of cell cycle-associated genes and leukemia inhibitory factor (Lif) and revealed alterations in expression of other IL-6-type cytokines and Jak-Stat signaling pathway components, including increased expression of IL-6 (1553%). In contrast, astrocytic glial fibrillary acidic protein (Gfap) message levels were unaltered, and other astrocytic markers were significantly downregulated. Microglial activation and vascular-associated gene responses were identified. CONCLUSIONS Cell proliferation and IL-6-type cytokine gene expression, rather than astrocyte hypertrophy, characterize early pressure-induced ONH injury.
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Affiliation(s)
- Elaine C Johnson
- Kenneth C. Swan Ocular Neurobiology Laboratory, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon 97201, USA.
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Chaudhary P, Marracci G, Yu X, Galipeau D, Morris B, Bourdette D. Lipoic acid decreases inflammation and confers neuroprotection in experimental autoimmune optic neuritis. J Neuroimmunol 2011; 233:90-6. [PMID: 21215462 DOI: 10.1016/j.jneuroim.2010.12.002] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 11/24/2010] [Accepted: 12/07/2010] [Indexed: 12/20/2022]
Abstract
Lipoic acid (LA) is an antioxidant that is effective in treating experimental autoimmune encephalomyelitis (EAE), a model for multiple sclerosis (MS). C57BL/6 mice with EAE develop experimental autoimmune optic neuritis (EAON), which models acute optic neuritis in humans. Here we determined whether LA is therapeutically effective in EAON. We immunized C57BL/6 mice with MOG 35-55 peptide. Mice received either daily subcutaneous injections of LA (100mg/kg) or saline in early or late suppression paradigms. In the early suppression paradigm, optic nerve cross-sections showed 14.9±3.8% (mean±SEM) damage in mice receiving saline (n=7) and 2.0±0.4% damage in mice given LA (n=7, p=0.001). In the late suppression paradigm, optic nerve sections showed 24.6±3.5% damage in mice treated with saline (n=7) and 8.4±2.5% in mice treated with LA (n=7, p=0.004). Thus a dramatic reduction in axonal injury was seen after LA administration in both experimental paradigms. Compared with saline treated mice with EAON, optic nerves from mice receiving LA had significantly fewer CD4+ and CD11b+ cells in both paradigms. This study provides a rationale for investigating the therapeutic efficacy of LA in acute optic neuritis in humans.
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Affiliation(s)
- Priya Chaudhary
- Department of Neurology, L226, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA
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Kisiswa L, Albon J, Morgan JE, Wride MA. Cellular inhibitor of apoptosis (cIAP1) is down-regulated during Retinal ganglion cell (RGC) maturation. Exp Eye Res 2010; 91:739-47. [DOI: 10.1016/j.exer.2010.08.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 08/20/2010] [Accepted: 08/26/2010] [Indexed: 10/19/2022]
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Joos KM, Li C, Sappington RM. Morphometric changes in the rat optic nerve following short-term intermittent elevations in intraocular pressure. Invest Ophthalmol Vis Sci 2010; 51:6431-40. [PMID: 20688743 DOI: 10.1167/iovs.10-5212] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE Intraocular pressure (IOP) fluctuations may occur in patients with glaucoma, but how these fluctuations affect axonal populations in the optic nerve and other structures in the eye has been difficult to assess. This study developed a rat model to evaluate the effect of intermittent controlled elevations in IOP on the morphology of the rat optic nerve. METHODS IOP was transiently elevated for 1 hour on each of 6 days a week over 6 weeks with an adjustable vascular loop around the right topically anesthetized eye of Sprague-Dawley rats. IOP was measured by pneumatonometer before, immediately after, and at the end of 1 hour of treatment with ligature. Globes and optic nerve segments were prepared for histology and morphometry. RESULTS Mean baseline IOP of 14.9 ± 1.8 mm Hg increased to 35.3 ± 2.6 mm Hg (P < 0.001) during 1-hour treatments and returned to 15.0 ± 2.2 mm Hg (P = 0.84) 1 hour after completion. The contralateral untreated eyes had a mean IOP of 14.2 ± 1.9 mm Hg at baseline and 14.6 ± 1.9 mm Hg at the end of treatment. Nerve fiber layer thinning (22%-25%) corresponded with a decrease (7%-10%) in soma number in the ganglion cell layer. Optic nerves displayed axonal degeneration with a modest axon loss of 6% and increased expression of glial acidic fibrillary protein in astrocytes. CONCLUSIONS Controlled daily 1-hour IOP elevations can be performed with an adjustable vascular loop in rats. After only 6 weeks, intermittent elevations in IOP produce changes in optic nerve consistent with early degeneration reported in chronic models of glaucoma.
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Affiliation(s)
- Karen M Joos
- Vanderbilt Eye Institute, Vanderbilt University, Nashville, TN 37232, USA.
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Zhao X, Pan Z, Wu J, Zhou G, Zeng Y. Automatic identification and morphometry of optic nerve fibers in electron microscopy images. Comput Med Imaging Graph 2009; 34:179-84. [PMID: 19796916 DOI: 10.1016/j.compmedimag.2009.08.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Revised: 07/18/2009] [Accepted: 08/31/2009] [Indexed: 11/19/2022]
Abstract
The neuroanatomical morphology of the optic nerve is an important description for understanding different aspects like topological distribution of nerves. Manual identification and morphometry has been usually considered as tedious, time consuming, and susceptible to error. A method that automates the identification and analysis of axons from electron micrographic images is presented. First, using region growing approach binarizes the image by combining the feature information together with spatial information, and obtains a coarse classification between myelin and non-myelin pixels. Next, identifies the axon candidates by region labeling and remove false axons on the basis of the identification ruler. Then the connected myelin sheaths are separated from each other using the maximum gradient magnitude of the outer annulus. Finally, analyses the morphological data of fibers. The developed method has been tested on a number of optic nerve images and results were presented. Regional distributions of axon caliber were unimodal. The thickness of the myelin sheath was highly correlated with the fiber diameter; hence, myelin sheath width was also distributed in a unimodal manner.
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Affiliation(s)
- Ximei Zhao
- College of Information Engineering, Qingdao University, Qingdao, China
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Yang H, Downs JC, Sigal IA, Roberts MD, Thompson H, Burgoyne CF. Deformation of the normal monkey optic nerve head connective tissue after acute IOP elevation within 3-D histomorphometric reconstructions. Invest Ophthalmol Vis Sci 2009; 50:5785-99. [PMID: 19628739 DOI: 10.1167/iovs.09-3410] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To characterize optic nerve head (ONH) connective tissue deformation after acute (15 or 30 minutes) intraocular pressure (IOP) elevation in six adult normal monkeys using three-dimensional (3-D) histomorphometry. METHODS Trephined ONH and peripapillary sclera from both eyes of six monkeys, each perfusion fixed with one eye at IOP 10 mm Hg (IOP-10) and the other at IOP 30 or 45 mm Hg (IOP-30 or IOP-45, by anterior chamber manometer), were serially sectioned, 3-D reconstructed, 3-D delineated, and quantified according to standard parameters. For each monkey, intereye differences (high-IOP eye minus IOP-10) for each parameter were calculated and compared by ANOVA and EPIDmax both overall and regionally. EPIDmax deformations for each parameter were defined to be those statistically significant differences that exceeded the maximum physiologic intereye difference within six bilaterally normal monkeys in a previous report. RESULTS Regional EPIDmax laminar thinning, posterior bowing of the peripapillary sclera, and thinning and expansion of the scleral canal were present in most high-IOP eyes and were colocalized in those demonstrating the most deformation. Laminar deformation was minimal, not only posteriorly but in some cases anteriorly in the high-IOP eyes. No increase in deformation was seen in the IOP-45 versus the IOP-30 eyes. CONCLUSIONS ONH connective tissue alterations after acute IOP elevation involve regional thinning, stretching, and deformation of the lamina cribrosa and peripapillary sclera that are minimal to modest in magnitude. The time-dependent character of these alterations and their compressive, expansile, and shear effects on the axons, the astrocytes, and the laminar and posterior ciliary circulations remain to be determined.
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Affiliation(s)
- Hongli Yang
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Health System, Portland, Oregon 97208-3950, USA
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Morrison JC, Johnson E, Cepurna WO. Rat models for glaucoma research. PROGRESS IN BRAIN RESEARCH 2009; 173:285-301. [PMID: 18929117 DOI: 10.1016/s0079-6123(08)01121-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Rats are becoming an increasingly popular model system for understanding mechanisms of optic nerve injury in primary open-angle glaucoma (POAG). Although the anatomy of the rat optic nerve head (ONH) is different from the human, the ultrastructural relationships between astrocytes and axons are quite similar, making it likely that cellular processes of axonal damage in these models will be relevant to human glaucoma. All of these models rely on elevating intraocular pressure (IOP), a major risk factor for glaucoma. Methods that produce increased resistance to aqueous humor outflow at the anterior chamber angle, specifically hypertonic saline injection of aqueous outflow pathways and laser treatment of the limbal tissues, appear to produce a specific regional pattern of injury that may have a particular relevance to understanding regional injury in human glaucoma. Because increased pressure fluctuations are a characteristic of such models and the rodent ONH appears to have high susceptibility to elevated IOP, special instrumentation and measurement techniques are required to document pressure exposure in these eyes and understand the pressure levels that the eyes and the optic nerve are exposed to. With these techniques, it is possible to obtain an excellent correlation between pressure and the extent of nerve damage. Continued use of these models will lead to a better understanding of cellular mechanisms of pressure-induced optic nerve damage and POAG.
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Affiliation(s)
- John C Morrison
- Casey Eye Institute, Oregon Health & Science University, Portland, OR, USA.
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Strouthidis NG, Yang H, Fortune B, Downs JC, Burgoyne CF. Detection of optic nerve head neural canal opening within histomorphometric and spectral domain optical coherence tomography data sets. Invest Ophthalmol Vis Sci 2009; 50:214-23. [PMID: 18689697 PMCID: PMC2726821 DOI: 10.1167/iovs.08-2302] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To assess the ability to detect the neural canal opening (NCO) and its characteristics within three-dimensional (3-D) histomorphometric and 3-D spectral domain optical coherence tomography (SD-OCT) reconstructions of the optic nerve head from nonhuman primate (NHP) eyes. METHODS NCO was delineated within 40 radial, sagittal sections of 3-D histomorphometric reconstructions of 44 normal eyes of 38 NHPs, each perfusion fixed at IOP 10 mm Hg, and 3-D SD-OCT (Spectralis; Heidelberg Engineering, Heidelberg, Germany) volumes acquired in vivo from a separate group of 33 normal eyes of 24 NHPs. Within all reconstructions, a least-squares ellipse was fitted to the 80 NCO points. For each eye, the dimensions and plane error (a gauge of planarity) of the fitted ellipse were calculated. RESULTS The NCO was successfully delineated within every section of each histomorphometric and SD-OCT reconstruction. Median plane error was similar within histomorphometric and SD-OCT volumes (8 microm, range 4-19, histomorphometry, and 10 microm, range 4-26, SD-OCT) and was small relative to the size of the ellipse. Median histomorphometric ellipse dimensions were 1453 mum (major axis, range 1218-1737) and 1066 microm (minor axis, range 808-1263). Median SD-OCT ellipse dimensions were 1512 microm (major axis, range 1191-1865) and 1060 microm (minor axis, range 772-1248). CONCLUSIONS The NCO is biologically continuous and relatively planar within all 3-D histomorphometric and SD-OCT reconstructions. These characteristics support its further evaluation as a reference plane for cross-sectional and longitudinal measurement of optic nerve head structures using 3-D SD-OCT.
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Affiliation(s)
- Nicholas G. Strouthidis
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Health System, Portland, Oregon
| | - Hongli Yang
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Health System, Portland, Oregon
- Biomedical Engineering Department, Tulane University, New Orleans, Louisiana
| | - Brad Fortune
- Electrodiagnostic Services, Devers Eye Institute, Legacy Health System, Portland, Oregon
| | - J. Crawford Downs
- Ocular Biomechanics Laboratory, Devers Eye Institute, Legacy Health System, Portland, Oregon
| | - Claude F. Burgoyne
- Optic Nerve Head Research Laboratory, Devers Eye Institute, Legacy Health System, Portland, Oregon
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Mansour H, Chamberlain CG, Weible MW, Hughes S, Chu Y, Chan-Ling T. Aging-related changes in astrocytes in the rat retina: imbalance between cell proliferation and cell death reduces astrocyte availability. Aging Cell 2008; 7:526-40. [PMID: 18489730 DOI: 10.1111/j.1474-9726.2008.00402.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The aim of this study was to investigate changes in astrocyte density, morphology, proliferation and apoptosis occurring in the central nervous system during physiological aging. Astrocytes in retinal whole-mount preparations from Wistar rats aged 3 (young adult) to 25 months (aged) were investigated qualitatively and quantitatively following immunofluorohistochemistry. Glial fibrillary acidic protein (GFAP), S100 and Pax2 were used to identify astrocytes, and blood vessels were localized using Griffonia simplicifolia isolectin B4. Cell proliferation was assessed by bromodeoxyuridine incorporation and cell death by TUNEL-labelling and immunolocalization of the apoptosis markers active caspase 3 and endonuclease G. The density and total number of parenchymal astrocytes in the retina increased between 3 and 9 months of age but decreased markedly between 9 and 12 months. Proliferation of astrocytes was detected at 3 months but virtually ceased beyond that age, whereas the proportion of astrocytes that were TUNEL positive and relative expression of active caspase 3 and endonuclease G increased progressively with aging. In addition, in aged retinas astrocytes exhibited gliosis-like morphology and loss of Pax2 reactivity. A small population of Pax2(+)/GFAP(-) cells was detected in both young adult and aged retinas. The reduction in the availability of astrocytes in aged retinas and other aging-related changes reported here may have a significant impact on the ability of astrocytes to maintain homeostasis and support neuronal function in old age.
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Affiliation(s)
- Hussein Mansour
- School of Medical Sciences (Anatomy and Histology) and Bosch Institute, University of Sydney, Sydney, NSW 2006, Australia.
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Premise and prediction-how optic nerve head biomechanics underlies the susceptibility and clinical behavior of the aged optic nerve head. J Glaucoma 2008; 17:318-28. [PMID: 18552618 DOI: 10.1097/ijg.0b013e31815a343b] [Citation(s) in RCA: 152] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
We propose that age-related alterations in optic nerve head (ONH) biomechanics underlie the clinical behavior and increased susceptibility of the aged ONH to glaucomatous damage. The literature which suggests that the aged ONH is more susceptible to glaucomatous damage at all levels of intraocular pressure is reviewed. The relevant biomechanics of the aged ONH are discussed and a biomechanical explanation for why, on average, the stiffened peripapillary scleral and lamina cribrosa connective tissues of the aged eye should lead to a shallow (senile sclerotic) form of cupping is proposed. A logic for why age-related axon loss and the optic neuropathy of glaucoma in the aged eye may overlap is discussed. Finally, we argue for a need to characterize all forms of clinical cupping into prelaminar and laminar components so as to add precision to the discussion of clinical cupping which does not currently exist. Such characterization may lead to the early detection of ONH axonal and connective tissue pathology in ocular hypertension and eventually aid in the assessment of etiology in all forms of optic neuropathy including those that may be purely age-related.
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Fileta JB, Huang W, Kwon GP, Filippopoulos T, Ben Y, Dobberfuhl A, Grosskreutz CL. Efficient estimation of retinal ganglion cell number: a stereological approach. J Neurosci Methods 2007; 170:1-8. [PMID: 18241929 DOI: 10.1016/j.jneumeth.2007.12.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2007] [Revised: 12/13/2007] [Accepted: 12/13/2007] [Indexed: 11/20/2022]
Abstract
Retinal ganglion cells (RGCs) are the only output neurons of the retina, and their degeneration after damage to the optic nerve or in glaucoma is a well established system for studying apoptosis in the central nervous system. Frequently used procedures for assessing RGC number in retinal flat mounts suffer from two problems: RGC densities are not uniform across retinal flat mounts, and density measures may therefore not reflect total number, and flat mounts do not allow efficient use of tissue. To overcome these problems we developed a stereological method for efficiently assessing RGC number in cryostat sections of the retina. We empirically demonstrate that only approximately 1:20 sections need be assessed to accurately estimate the total number of RGCs in the rat retina, providing ample tissue for additional studies in the same retina and saving considerably on more exhaustive sampling strategies. Using this method, we estimate that there are 86,282+/-4759 RGCs in the normal Brown Norway rat retina. These counts match well with estimates of axon counts in optic nerve. In a pilot study of experimental glaucoma, we determined a reduction of RGCs to 53,862+/-4272 (p<0.05). The current technique should prove advantageous to assess neuroprotective strategies in these experimental models.
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Affiliation(s)
- John B Fileta
- Howe Laboratory of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, 243 Charles Street, Boston, MA 02114, USA
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No age-related cell loss in three retinal nuclear layers of the Long-Evans rat. Vis Neurosci 2007; 24:799-803. [DOI: 10.1017/s0952523807070721] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 09/11/2007] [Indexed: 11/06/2022]
Abstract
The retina mainly contains ganglion, bipolar and photoreceptor cells which are distributed in the ganglion cell layer (GCL), inner nuclear layer (INL) and outer nuclear layer (ONL), respectively. Whether there is an age-related loss of these retinal cells remains not well understood. Cell density and the total number of cells were two commonly used measures to evaluate such age-related changes in most previous studies and provided controversial conclusions. The use of density measures as decisive data is problematic because the total area of the retina was expanded in aging, whereas the application of the total number of cells was limited for assessing ganglion cells. In this study, thus, we wanted to test whether there is an age-related cell loss in the GCL, INL and ONL and if so, whether such a loss is correlated to the convergence ratio of these cells. We used stereological procedures to quantify the total number of cells in the three retinal nuclear layers in six young and six aged Long-Evans rats. We found that during aging, the total volume of the retina remained unchanged, but the retina became thinner. There was no cell loss in each individual nuclear layer, and the ratio of the ONL to INL to GCL was preserved.
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50
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Danylkova NO, Alcala SR, Pomeranz HD, McLoon LK. Neuroprotective effects of brimonidine treatment in a rodent model of ischemic optic neuropathy. Exp Eye Res 2006; 84:293-301. [PMID: 17113077 DOI: 10.1016/j.exer.2006.10.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Revised: 09/05/2006] [Accepted: 10/02/2006] [Indexed: 01/26/2023]
Abstract
Ischemic optic neuropathy (ION) is a common disorder caused by disruption of the arterial blood supply to the optic nerve. It can result in significant loss of visual acuity and/or visual field. An ischemic optic nerve injury was produced in rats by intravenous injection of Rose Bengal dye followed by argon green laser application to the retinal arteries overlying the optic nerve, causing a coagulopathy within the blood vessels and disruption of optic nerve and retinal perfusion. The effect of brimonidine tartrate eye drops on survival of retinal ganglion cell axons in this experimental paradigm was studied. One eye was treated and the contralateral eye served as a control. Four groups of animals were used for this study. Group 1 received 7 days of treatment with 0.15% brimonidine tartrate eye drops twice a day prior to the ischemic injury. Group 2 animals received 0.15% brimonidine tartrate eye drops twice a day for 14 days after photocoagulation injury. Animal groups 3 and 4 received eye drops of 0.9% NaCl twice a day either daily for 7 days before injury or daily for 14 days, respectively. All rats were sacrificed 5 months after the injury to ascertain long-term optic axon survival. Coagulopathy-induced optic nerve ischemia resulted in a 71% loss of optic axons. Treatment with brimonidine daily for the 7 days prior to the injury resulted in a greater survival of optic axons, with only a 56.1% loss compared to control. Brimonidine treatment every day for 14 days after the ischemic injury did not result in a significant rescue of optic axons compared to injury alone. In summary, the application of brimonidine eye drops for one week prior to an ischemic injury resulted in a statistically significant increase in survival of optic axons within the injured optic nerves. Brimonidine treatment of the eye after the ischemic injury did not result in axon rescue, and axon loss was similar to the injured optic nerves treated with saline only. These results suggest that brimonidine may have potential use for prevention of ION in at-risk patients.
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Affiliation(s)
- Nataliya O Danylkova
- Department of Ophthalmology, University of Minnesota, Minneapolis, MN 55455, USA
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