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Senanayake PD, Bonilha VL, W Peterson J, Yamada Y, Karnik SS, Daneshgari F, Brosnihan KB, Hollyfield JG. Retinal angiotensin II and angiotensin-(1-7) response to hyperglycemia and an intervention with captopril. J Renin Angiotensin Aldosterone Syst 2019; 19:1470320318789323. [PMID: 30126320 PMCID: PMC6104213 DOI: 10.1177/1470320318789323] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Hypothesis: Hyperglycemia decreases angiotensin-(1-7), the endogenous counter-regulator of angiotensin II in the retina. Materials and methods: The distribution and levels of retinal angiotensin II (Ang II) and angiotensin-(1-7) (Ang-(1-7)) were evaluated by confocal imaging and quantitative immunohistochemistry during the development of streptozotocin-induced diabetes in rats. Results: In the nondiabetic eye, Ang II was localized to the endfeet of Müller cells, extending into the cellular processes of the inner plexiform layer and inner nuclear layer; Ang-(1-7) showed a wider distribution, extending from the foot plates of the Müller cells to the photoreceptor layer. Eyes from diabetic animals showed a higher intensity and extent of Ang II staining compared with nondiabetic eyes, but lower intensity with a reduced distribution of Ang-(1-7) immunoreactivity. Treatment of the diabetic animals with the angiotensin-converting enzyme inhibitor (ACEI) captopril showed a reduced intensity of Ang II staining, whereas increased intensity and distribution were evident with Ang-(1-7) staining. Conclusions: These studies reveal that pharmacological inhibition with ACEIs may provide a specific intervention for the management of the diabetes-induced decline in retinal function, reversing the profile of the endogenous angiotensin peptides closer to the normal condition.
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Affiliation(s)
- Preenie deS Senanayake
- 1 Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, USA.,2 Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, USA
| | - Vera L Bonilha
- 1 Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, USA.,2 Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, USA
| | - John W Peterson
- 3 Reseach Core Services (Imaging) Cleveland Clinic, Cleveland, USA
| | - Yoshiro Yamada
- 4 Department of Urology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Sadashiva S Karnik
- 5 Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, USA
| | - Firouz Daneshgari
- 6 Department of Urology (FD), Case Western Reserve University, University Hospitals Case Medical Center, Cleveland, USA
| | - K Bridget Brosnihan
- 7 Department of Surgery, Hypertension & Vascular Research, Cardiovascular Sciences Center, Wake Forest University School of Medicine, Winston-Salem, USA
| | - Joe G Hollyfield
- 1 Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, USA.,2 Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University, Cleveland, USA
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2
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Bejarano-Escobar R, Holguín-Arévalo MS, Montero JA, Francisco-Morcillo J, Martín-Partido G. Macrophage and microglia ontogeny in the mouse visual system can be traced by the expression of Cathepsins B and D. Dev Dyn 2011; 240:1841-55. [PMID: 21648018 DOI: 10.1002/dvdy.22673] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2011] [Indexed: 01/11/2023] Open
Abstract
Here, we show a detailed chronotopographical analysis of cathepsin B and D expression during development of the mouse visual system. Both proteases were detected in large rounded/ameboid cells usually located in close relationship with prominent sites of extensive physiological cell death. In concordance with their morphological features and topographical distribution, we demonstrate that expressing cells corresponded with macrophages and microglial precursors. We found that as microglial precursors differentiated the expression of both cathepsins was down-regulated. Of interest, cathepsin B and D transcripts were never observed in degenerating cells. Our findings point to a role for cathepsin D and B in cell debris degradation after apoptotic processes rather than promoting cell death, as proposed for other developmental models. Additionally their pattern of expression suggests a role in the maturation of the microglial precursors.
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Affiliation(s)
- Ruth Bejarano-Escobar
- Departamento de Biología Celular, Facultad de Ciencias, Universidad de Extremadura, Badajoz, Spain
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3
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Lipid peroxidation products reduce lysosomal protease activities in human retinal pigment epithelial cells via two different mechanisms of action. Exp Eye Res 2009; 90:261-6. [PMID: 19895809 DOI: 10.1016/j.exer.2009.10.014] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 10/27/2009] [Accepted: 10/28/2009] [Indexed: 11/22/2022]
Abstract
In age-related macular degeneration (AMD), reduced lysosomal capacity may contribute to lipofuscinogenesis and progressive dysfunction of the retinal pigment epithelium (RPE). We previously demonstrated that lipid peroxidation-related protein modifications inhibit lysosomal degradation of photoreceptor outer segment (POS) proteins in RPE cells. Herein, we investigate the effects of lipid peroxidation products on activities of key RPE lysosomal proteases. In lysosomes isolated from primary human RPE cells, lipid peroxidation products 4-hydroxynonenal (HNE) and malondialdehyde (MDA) exerted a dose-dependent inhibitory effect on cysteine proteases cathepsin B and L, with biologically relevant concentrations of 1 muM resulting in a reduction of enzyme activities by 88-94%. This effect was confirmed in cultured RPE cells. Using mass spectrometry, covalent HNE and MDA adducts were detected in the active center region of inactivated cathepsins. POS previously modified with HNE and MDA likewise caused a dose-dependent reduction of cathepsin B and L activities in isolated lysosomes and, in addition, inhibited the aspartic protease cathepsin D. Our results indicate that lipid peroxidation products in vitro interfere with RPE lysosomal protease activities by two different mechanisms of action: (i) HNE and MDA directly inactivate lysosomal cysteine proteases by covalent binding to the active center; (ii) HNE- and MDA-mediated protein modifications convert proteolytic substrates into competitive inhibitors of lysosomal proteases. Via these mechanisms, lipid peroxidation products may induce lysosomal dysfunction and lipofuscinogenesis in the aging RPE and thus contribute to the pathogenesis of AMD.
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4
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Chavarría T, Valenciano AI, Mayordomo R, Egea J, Comella JX, Hallböök F, de Pablo F, de la Rosa EJ. Differential, age-dependent MEK-ERK and PI3K-Akt activation by insulin acting as a survival factor during embryonic retinal development. Dev Neurobiol 2007; 67:1777-88. [PMID: 17659595 DOI: 10.1002/dneu.20554] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Programmed cell death is a genuine developmental process of the nervous system, affecting not only projecting neurons but also proliferative neuroepithelial cells and young neuroblasts. The embryonic chick retina has been employed to correlate in vivo and in vitro studies on cell death regulation. We characterize here the role of two major signaling pathways, PI3K-Akt and MEK-ERK, in controlled retinal organotypic cultures from embryonic day 5 (E5) and E9, when cell death preferentially affects proliferating neuroepithelial cells and ganglion cell neurons, respectively. The relative density of programmed cell death in vivo was much higher in the proliferative and early neurogenic stages of retinal development (E3-E5) than during neuronal maturation and synaptogenesis (E8-E19). In organotypic cultures from E5 and E9 retinas, insulin, as the only growth factor added, was able to completely prevent cell death induced by growth factor deprivation. Insulin activated both the PI3K-Akt and the MEK-ERK pathways. Insulin survival effect, however, was differentially blocked at the two stages. At E5, the effect was blocked by MEK inhibitors, whereas at E9 it was blocked by PI3K inhibitors. The cells which were found to be dependent on insulin activation of the MEK-ERK pathway at E5 were mostly proliferative neuroepithelial cells. These observations support a remarkable specificity in the regulation of early neural cell death.
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Affiliation(s)
- Teresa Chavarría
- Department of Cellular and Molecular Physiopathology, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
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5
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Valenciano AI, Corrochano S, de Pablo F, de la Villa P, de la Rosa EJ. Proinsulin/insulin is synthesized locally and prevents caspase- and cathepsin-mediated cell death in the embryonic mouse retina. J Neurochem 2007; 99:524-36. [PMID: 17029604 DOI: 10.1111/j.1471-4159.2006.04043.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Programmed cell death is an essential, highly regulated process in neural development. Although the role of insulin-like growth factor I in supporting the survival of neural cells has been well characterized, studies on proinsulin/insulin are scarce. Here, we characterize proinsulin/insulin effects on cell death in embryonic day 15.5 mouse retina. Both proinsulin mRNA and proinsulin/insulin immunoreactivity were found in the developing retina. Organotypic embryonic day 15.5 retinas cultured under growth factor deprivation showed an increase in cell death that was reversed by proinsulin, insulin and insulin-like growth factor I, with similar median effective concentration values via phosphatidylinositol-3-kinase activation. Although insulin and insulin-like growth factor I provoked a sustained Akt phosphorylation, proinsulin-induced phosphorylation of Akt was not found. Analysis of the growth factor deprivation-induced cell death mechanisms, using caspase and cathepsin inhibitors, demonstrated that both protease families were required for the effective execution of cell death. The insulin survival effect, which decreased the extent and distribution of cell death to levels similar to those found in vivo, was not enhanced by simultaneous treatment with caspase and cathepsin inhibitors, suggesting that insulin interferes with these protease pathways in the embryonic mouse retina. The mechanisms characterized in this study provide new details on early neural cell death and its genuine regulation by insulin/proinsulin.
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Affiliation(s)
- Ana I Valenciano
- Group of Growth Factors in Vertebrate Development, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
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6
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Alizadeh P, Smit-McBride Z, Oltjen SL, Hjelmeland LM. Regulation of cysteine cathepsin expression by oxidative stress in the retinal pigment epithelium/choroid of the mouse. Exp Eye Res 2006; 83:679-87. [PMID: 16684524 PMCID: PMC1661778 DOI: 10.1016/j.exer.2006.03.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2005] [Revised: 02/16/2006] [Accepted: 03/14/2006] [Indexed: 11/24/2022]
Abstract
Cystatin C is the major inhibitor of the cysteine cathepsins. Polymorphisms in the cystatin C gene have recently been associated with the risk of developing Age-related Macular Degeneration (AMD). Oxidative stress is also thought to play a key role in the pathogenesis of AMD. We surveyed the retinal pigment epithelium (RPE) and choroid of the C57BL/6J mouse for the expression of the cysteine cathepsins under normoxic and hyperoxic (75% O(2)) conditions. Microarray analysis of RPE/choroid mRNA revealed the expression of cathepsins B and L, as well as cystatin C under all experimental conditions. The microarray results were confirmed by real-time quantitative polymerase chain reaction (PCR). Localization of the mRNA species for cystatin C and cathepsin B, as well as, localization of protein species for cystatin C, cathepsins B and L were performed to evaluate the tissue distribution of these species. Our results indicate that cystatin C is largely synthesized in the RPE and secreted from the basal side. Cathepsin B is the major cysteine protease in the RPE and choroid. The expression of all mRNAs and proteins was elevated by exposure to oxidative stress.
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Affiliation(s)
| | | | | | - Leonard M. Hjelmeland
- * Corresponding author: Leonard M. Hjelmeland,
Professor, , Department of
Ophthalmology, Vitreoretinal Research Lab, University of California, One Shields
Ave. Davis CA 95616, USA, PH: (530) 752-2250, FX: (530) 752-2270
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7
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Wassélius J, Wallin H, Abrahamson M, Ehinger B. Cathepsin B in the rat eye. Graefes Arch Clin Exp Ophthalmol 2003; 241:934-42. [PMID: 14586591 DOI: 10.1007/s00417-003-0782-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2003] [Revised: 09/02/2003] [Accepted: 09/03/2003] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND Cathepsin B is a mammalian cysteine protease. The enzyme has been suggested to participate in the patophysiological processes of keratoconus as well as in the corneal response to infectious agents. This study describes the localization of cathepsin B in the rat eye. METHODS Cathepsin B was identified in rat ocular tissues by Western blotting and immunohistochemistry. Cathepsin B mRNA levels were analyzed in the tissues by quantitative real-time cDNA amplification (QRT-PCR). RESULTS Cathepsin B is present in the epithelium, in stromal cells and in the endothelium of the cornea. It is also present in the epithelium lining the ciliary processes, in occasional stromal cells in the iris, in the anterior subcapsular lens epithelium and in various cell types in the retina. At all locations cathepsin B is present in cytoplasmic granules, presumably lysosomes. QRT-PCR analysis detected cathepsin B mRNA in all these tissues in amounts correlating to the immunodetection results, suggesting that the enzyme detected is locally produced. CONCLUSIONS Cathepsin B is present in several tissues and cell types throughout the rat eye. It is localized to cytoplasmic granules, presumably lysosomes. Our results suggest that it is probably also produced in the same cell types.
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Affiliation(s)
- Johan Wassélius
- Department of Ophthalmology, University of Lund, 221 85, Lund, Sweden.
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8
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Koike M, Shibata M, Ohsawa Y, Nakanishi H, Koga T, Kametaka S, Waguri S, Momoi T, Kominami E, Peters C, Figura KV, Saftig P, Uchiyama Y. Involvement of two different cell death pathways in retinal atrophy of cathepsin D-deficient mice. Mol Cell Neurosci 2003; 22:146-61. [PMID: 12676526 DOI: 10.1016/s1044-7431(03)00035-6] [Citation(s) in RCA: 108] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
To understand the mechanisms of retinal atrophy in cathepsin D-deficient mice, the postnatal development of their retinae was analyzed. TUNEL-positive cells appeared abundantly in the outer nuclear layer (ONL) and slightly in the inner nuclear layer (INL). Nitric oxide synthase (NOS) was induced in microglial cells which invaded retinal layers and phagocytosed dead cell debris, while NOS inhibitors prevented cell death in the INL but not in the ONL. Caspases 9 and 3 were activated only in the ONL after P15. Moreover, no atrophic change was detected in the retina of mice deficient in cathepsin B or L. These results suggest that cathepsin D is essential for the metabolic maintenance of retinal photoreceptor cells and that its deficiency induces apoptosis of the cells, while the loss of INL neurons is mediated by NO from microglial cells.
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Affiliation(s)
- Masato Koike
- Department of Cell Biology and Neurosciences, Osaka University Graduate School of Medicine, 565-0871, Suita, Osaka, Japan
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9
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Wang XD, Kashii S, Zhao L, Tonchev AB, Katsuki H, Akaike A, Honda Y, Yamashita J, Yamashima T. Vitamin B6 protects primate retinal neurons from ischemic injury. Brain Res 2002; 940:36-43. [PMID: 12020872 DOI: 10.1016/s0006-8993(02)02587-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Vitamin B6 derivatives protect the retinal neurons from excitotoxic injury in vitro. However, their in vivo role in a process involving excitotoxicity, such as ischemia, remains unknown. We studied potential protective effects of pyridoxal 5'-phosphate (PLP) and pyridoxal hydrochloride (pyridoxal) on the retinal neurons in a monkey model of transient global ischemia. Daily intravenous injections (15 mg/kg) of pyridoxal and PLP were performed for consecutive 10 days. On the sixth day, whole brain complete ischemia was produced by clipping the innominate and the left subclavian arteries for 20 min. The monkeys were sacrificed 5 days after ischemia and their retinas were processed for histological analysis. The ischemia induced a marked cellular injury in the retina as shown by the loss of ganglion cells and the reduction of thickness of the ganglion cell, inner plexiform, and inner nuclear layers. PLP significantly prevented the ganglion cell loss and the reduction of thickness of the ganglion cell layer. Pyridoxal significantly prevented the ganglion cell loss as well as the reduction of thickness of ganglion cell, inner plexiform and inner nuclear layers. These results suggest that PLP and pyridoxal counteract the postischemic neuronal death in the adult primate retina, offering a potential for a novel pharmacotherapy of retinal ischemic injury.
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Affiliation(s)
- Xiang-Di Wang
- Department of Neurosurgery, Division of Neuroscience, Graduate School of Medical Science, Kanazawa University, Takaramachi 13-1, 920-8641, Kanazawa, Japan
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10
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Bernstein HG, Reichenbach A, Wiederanders B. Cathepsin E immunoreactivity in human ocular tissues: influence of aging and pathological states. Neurosci Lett 1998; 240:135-8. [PMID: 9502222 DOI: 10.1016/s0304-3940(97)00946-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We studied the antigenic expression of the aspartic proteinase cathepsin E in normal and pathologic human ocular tissues obtained from donors of different age. In the retina the enzyme was immunolocalized in neurons of outer and inner plexiform layers and in few ganglionic neurons. Muller cells were also sometimes immunoreactive for cathepsin E. An increase of neuronal enzyme immunoreactivity with age was evident. Immunocompetent blood cells invading the vitreous body were strongly immunostained for the enzyme. The enzyme is possibly involved in the retinal protein metabolism and might play immunological roles in certain pathologic events.
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Affiliation(s)
- H G Bernstein
- Department of Psychiatry, Medical Faculty, Otto von Guericke University Magdeburg, Germany
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11
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El-Hifnawi E, BenEzra D, Reichenbach A, Hettlich HJ. Distribution of cathepsin D in human ocular tissue: An immunohistochemical study. Ann Anat 1995. [DOI: 10.1016/s0940-9602(11)80083-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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12
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Reichenbach A, Fuchs U, Kasper M, el-Hifnawi E, Eckstein AK. Hepatic retinopathy: morphological features of retinal glial (Müller) cells accompanying hepatic failure. Acta Neuropathol 1995; 90:273-81. [PMID: 8525801 DOI: 10.1007/bf00296511] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
More than 80 years ago, Alzheimer described changes in the brains of patients who had suffered hepatic failure. Astrocytes are primarily affected; their nuclei become swollen, their intermediate filament protein composition is altered and their cytoplasm becomes vacuolated. Cells with these features are called Alzheimer type II astrocytes and these changes have been attributed to the toxic effects of elevated ammonia levels. The present study investigates whether the dominant glia of another part of the central nervous system, the Müller cells of the retina, undergo similar changes. Retinae of patients who had died with symptoms of hepatic failure were processed for histology, histochemistry, and immunocytochemistry. Cell nuclei were measured from brain astrocytes (insula cortex), Müller cells, and retinal bipolar neurons. Hepatic failure resulted in the enlargement of nuclei in astrocytes and Müller cells, and the enhanced expression in Müller cells of glial fibrillary acidic protein, cathepsin D, and the beta-subunit of prolyl 4-hydroxylase (glial-p55). In some retinae, signs of gliosis were also observed. We conclude that increased levels of serum ammonia resulting from hepatic insufficiency cause changes in Müller cells that are similar to those seen in brain astrocytes. We term this condition hepatic retinopathy.
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Affiliation(s)
- A Reichenbach
- Paul Flechsig Institute for Brain Research, Leipzig University, Germany
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13
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Härtig W, Grosche J, Distler C, Grimm D, el-Hifnawi E, Reichenbach A. Alterations of Müller (glial) cells in dystrophic retinae of RCS rats. JOURNAL OF NEUROCYTOLOGY 1995; 24:507-17. [PMID: 7561959 DOI: 10.1007/bf01179976] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We have carried out a light microscopical study of Müller cells in the retinae of rats with inherited retinal dystrophy (Royal College of Surgeons rats). Isolated retinae of both control and Royal College of Surgeons rats were exposed to a Procion Yellow solution which is taken up selectively into Müller cells. The shape of the cells was then studied by confocal microscopy. Enzymatically isolated Müller cells were studied immunocytochemically with antibodies against glial fibrillary acidic protein, cathepsin D, beta-amyloid precursor protein, bcl-2 protooncogene product, and glutamine synthetase. Müller cells from RCS retinae were shorter than those from control retinae, and showed a coarse hypertrophy of their distal (sclerad) processes. In Müller cells isolated from the retinae of Royal College of Surgeon's rats, the expression of glial fibrillary acidic protein, cathepsin D, beta-amyloid precursor protein and bcl-2 protooncogene product was increased, and the expression of glutamine synthetase was reduced. Obviously, loss of neighbouring neurons leads to major alterations of both the shape and metabolism of Müller cells. The expression of enzymes that serve functional glio-neuronal interactions, such as glutamine synthetase, seems to be down-regulated, whereas proteins involved in cell reconstruction (cathepsin D), cell repair (possibly beta-amyloid precursor protein), and protection against apoptotic cell death (bcl-2 protooncogene product), are up-regulated, together with the 'pathological marker' glial fibrillary acidic protein.
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Affiliation(s)
- W Härtig
- Paul Flechsig Institute for Brain Research, Leipzig University, Germany
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14
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Reichenbach A, Stolzenburg JU, Wolburg H, Härtig W, el-Hifnawi E, Martin H. Effects of enhanced extracellular ammonia concentration on cultured mammalian retinal glial (Müller) cells. Glia 1995; 13:195-208. [PMID: 7782105 DOI: 10.1002/glia.440130306] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Müller (glial) cells of the neonatal rabbit retina were cultured as confluent monolayers and exposed to enhanced concentrations of ammonia (0.25, 0.5, 1, 3, 7, and 10 mM) in medium for various periods (30 min to 10 d). This caused, in a time- and dose-dependent manner, similar changes in the Müller cells as had previously been described in cultured astrocytes. The most conspicuous events were 1) an increasing size of cell nuclei, 2) an accumulation of phagocytotic vacuoles, and 3) a rearrangement of intermediate filaments. 4) A considerable number of cells died when higher ammonia concentrations were applied for more than 1 h. Simultaneous application of dibutyryl-cyclic adenosine monophosphate (dBcAMP) prevented almost completely both the increase in cell nucleus size and the changes of intermediate filaments, but only partly the early cell death of a subpopulation of cells, and the accumulation of phagocytotic vacuoles. Further changes evoked by enhanced ammonia concentration were 5) an accumulation of lipofuscin-like material ("fatty degeneration") revealed by lipophilic stain, 6) reduced immunoreactivity for cathepsin D, and increased immunoreactivity for 7) glial fibrillary acidic protein, 8) glutamine synthetase, and 9) bcl-2 protooncogene protein. These findings are discussed in respect to the possible underlying pathophysiological mechanisms.
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Affiliation(s)
- A Reichenbach
- Carl Ludwig Institute of Physiology, Leipzig University, Germany
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15
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Abstract
Numerous studies have demonstrated that cathepsin D as a major lysosomal acid protease plays an important role in the degradation of protein in several tissues. An important function of the retinal pigment epithelium is to interact with the photoreceptor cells in the renewal process. During the renewal process, the RPE cell phagocytosis discarded photoreceptor discs which are then degraded in the RPE phagolysosomes. It is believed that cathepsin D plays a main role in the degradation of rod outer segments and rhodopsin into glycopeptides. The cellular localization of cathepsin D immunoreactivity was examined at the light microscopic level in the ocular tissues of non-affected RCS-rdy+ rats strain by use of the alkaline phosphatase-antialkaline phosphatase (APAAP) technique. The presence of cathepsin D immunoreactivity was found in the cell cytoplasm of the following ocular tissues: retinal pigment epithelium; Müller cells; ganglion cells; pigmented and non-pigmented ciliary body; iris tissue; epithelium and endothelium of the cornea; endothelium of various vessels, including the tunica vasculosa lentis. High activity of cathepsin D was found in the RPE cells, as well as in the cytoplasm of Müller cells, especially expressed in their foot plates lying close to the inner limiting membrane.
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Affiliation(s)
- E el-Hifnawi
- Department of Ophthalmology, Medical University of Lübeck, Germany
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16
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Bernstein HG, Kirschke H, Wiederanders B, Schmidt D, Rinne A. Antigenic expression of cathepsin B in aged human brain. Brain Res Bull 1990; 24:543-9. [PMID: 2357585 DOI: 10.1016/0361-9230(90)90157-u] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The lysosomal thiol proteinase, cathepsin B, has been localized in different regions of aged human brain by use of the peroxidase-antiperoxidase technique. Cathepsin B-immunoreactive material was detected in multiple neurons of human hippocampus, neocortical area A 10, prefrontal gyrus and nuc. basalis of Meynert as well as in single white matter astrocytes. In brains of Alzheimer disease-affected subjects cathepsin B was revealed in neuritic plaques too. Possible functional consequences with regard to normal aging, neuropeptide metabolism and pathological changes are discussed.
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Affiliation(s)
- H G Bernstein
- Institute of Anatomy, Medical Academy Magdeburg, GDR
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