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Han C, Li Y, Zheng X, Zhang X, Li G, Zhao L, Chen Z, Yang Y, Zhang W. AQP4- and Kir4.1-Mediated Müller Cell Oedema Is Involved in Retinal Injury Induced By Hypobaric Hypoxia. Mol Neurobiol 2024:10.1007/s12035-024-04382-3. [PMID: 39060906 DOI: 10.1007/s12035-024-04382-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 07/18/2024] [Indexed: 07/28/2024]
Abstract
Hypobaric hypoxia is the main cause of high-altitude retinopathy (HAR). Retinal oedema is the key pathological change in HAR. However, its pathological mechanism is not clear. In this study, a 5000-m hypobaric hypoxic environment was simulated. Haematoxylin and eosin (H&E) staining and electrophysiological (ERG) detection were used to observe the morphological and functional changes in the retina of mice under hypobaric hypoxia for 2-72 h. Toluidine blue staining and transmission electron microscopy were used to observe the morphology of Müller cells in the hypobaric hypoxia groups. The functional changes and oedema mechanism of Müller cells were detected by immunofluorescence and western blotting. The expression levels of glutamine synthetase (GS), glial fibrillary acidic protein (GFAP), aquaporin 4 (AQP4), and inwardly rectifying potassium channel subtype 4.1 (Kir4.1) in Müller cells were quantitatively analysed. This study revealed that retinal oedema gradually increased with prolonged exposure to a 5000-m hypobaric hypoxic environment. In addition, the ERG showed that the time delay and amplitude of the a-wave and b-wave decreased. The expression of GS decreased, and the expression of GFAP increased in Müller cells after exposure to hypobaric hypoxia for 4 h. At the same time, retinal AQP4 expression increased, and Kir4.1 expression decreased. The oedema and functional changes in Müller cells are consistent with the time point of retinal oedema. In conclusion, Müller cell oedema is involved in retinal oedema induced by hypobaric hypoxia. An increase in AQP4 and a decrease in Kir4.1 are the main causes of Müller cell oedema caused by hypobaric hypoxia.
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Affiliation(s)
- Cong Han
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Yuting Li
- Department of Pathology, Basic Medical School, Ningxia Medical University, Yinchuan, 750004, Ningxia, China
| | - Xingxing Zheng
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Xiaoxia Zhang
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Guonian Li
- Department of Traditional Chinese Medicine, Xi'an Baoshi Flower Changqing Hospital, Shaanxi, 710201, China
| | - Liangtao Zhao
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Zhaoqian Chen
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, China
| | - Yi Yang
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, China.
| | - Wenfang Zhang
- Department of Ophthalmology, The Second Hospital & Clinical Medical School, Lanzhou University, Lanzhou, 730000, Gansu, China.
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McAllister IL, Vijayasekaran S, McLenachan S, Bhikoo R, Chen FK, Zhang D, Kanagalingam E, Yu DY. Cytokine Levels in Experimental Branch Retinal Vein Occlusion Treated With Either Bevacizumab or Triamcinolone Acetonide. Transl Vis Sci Technol 2024; 13:13. [PMID: 38899953 PMCID: PMC11193067 DOI: 10.1167/tvst.13.6.13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 05/01/2024] [Indexed: 06/21/2024] Open
Abstract
Purpose To compare gene expression changes following branch retinal vein occlusion (BRVO) in the pig with and without bevacizumab (BEV) and triamcinolone acetonide (TA). Methods Photothrombotic BRVOs were created in both eyes of four groups of nine pigs (2, 6, 10, and 20 days). In each group, six pigs received intravitreal injections of BEV in one eye and TA in the fellow eye, with three pigs serving as untreated BRVO controls. Three untreated pigs served as healthy controls. Expression of mRNA of vascular endothelial growth factor (VEGF), glial fibrillary acidic protein (GFAP), dystrophin (DMD), potassium inwardly rectifying channel subfamily J member 10 protein (Kir4.1, KCNJ10), aquaporin-4 (AQP4), stromal cell-derived factor-1α (CXCL12), interleukin-6 (IL6), interleukin-8 (IL8), monocyte chemoattractant protein-1 (CCL2), intercellular adhesion molecule 1 (ICAM1), and heat shock factor 1 (HSF1) were analyzed by quantitative reverse-transcription polymerase chain reaction. Retinal VEGF protein levels were characterized by immunohistochemistry. Results In untreated eyes, BRVO significantly increased expression of GFAP, IL8, CCL2, ICAM1, HSF1, and AQP4. Expression of VEGF, KCNJ10, and CXCL12 was significantly reduced by 6 days post-BRVO, with expression recovering to healthy control levels by day 20. Treatment with BEV or TA significantly increased VEGF, DMD, and IL6 expression compared with untreated BRVO eyes and suppressed BRVO-induced CCL2 and AQP4 upregulation, as well as recovery of KCNJ10 expression, at 10 to 20 days post-BRVO. Conclusions Inflammation and cellular osmohomeostasis rather than VEGF suppression appear to play important roles in BRVO-induced retinal neurodegeneration, enhanced in both BEV- and TA-treated retinas. Translational Relevance Inner retinal neurodegeneration seen in this acute model of BRVO appears to be mediated by inflammation and alterations in osmohomeostasis rather than VEGF inhibition, which may have implications for more specific treatment modalities in the acute phase of BRVO.
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Affiliation(s)
- Ian L. McAllister
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia
- Lions Eye Institute, Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Sarojini Vijayasekaran
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia
- Lions Eye Institute, Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Samuel McLenachan
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia
- Lions Eye Institute, Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Riyaz Bhikoo
- Lions Eye Institute, Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Fred K. Chen
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia
- Lions Eye Institute, Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Western Australia, Australia
- Department of Ophthalmology, Royal Perth Hospital, Perth, Western Australia, Australia
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Victoria, Australia
| | - Dan Zhang
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia
- Lions Eye Institute, Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Emily Kanagalingam
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia
- Lions Eye Institute, Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Western Australia, Australia
| | - Dao-Yi Yu
- Centre for Ophthalmology and Visual Science, The University of Western Australia, Perth, Western Australia, Australia
- Lions Eye Institute, Centre for Ophthalmology and Visual Science, The University of Western Australia, Nedlands, Western Australia, Australia
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Chen WB, Wang YX, Wang HG, An D, Sun D, Li P, Zhang T, Lu WG, Liu YQ. Role of TPEN in Amyloid-β 25-35-Induced Neuronal Damage Correlating with Recovery of Intracellular Zn 2+ and Intracellular Ca 2+ Overloading. Mol Neurobiol 2023:10.1007/s12035-023-03322-x. [PMID: 37059931 DOI: 10.1007/s12035-023-03322-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 03/17/2023] [Indexed: 04/16/2023]
Abstract
The overproduction of neurotoxic amyloid-β (Aβ) peptides in the brain is a hallmark of Alzheimer's disease (AD). To determine the role of intracellular zinc ion (iZn2+) dysregulation in mediating Aβ-related neurotoxicity, this study aimed to investigate whether N, N, N', N'‑tetrakis (2‑pyridylmethyl) ethylenediamine (TPEN), a Zn2+‑specific chelator, could attenuate Aβ25-35‑induced neurotoxicity and the underlying mechanism. We used the 3-(4, 5-dimethyl-thiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay to measure the viability of primary hippocampal neurons. We also determined intracellular Zn2+ and Ca2+ concentrations, mitochondrial and lysosomal functions, and intracellular reactive oxygen species (ROS) content in hippocampal neurons using live-cell confocal imaging. We detected L-type voltage-gated calcium channel currents (L-ICa) in hippocampal neurons using the whole‑cell patch‑clamp technique. Furthermore, we measured the mRNA expression levels of proteins related to the iZn2+ buffer system (ZnT-3, MT-3) and voltage-gated calcium channels (Cav1.2, Cav1.3) in hippocampal neurons using RT-PCR. The results showed that TPEN attenuated Aβ25-35‑induced neuronal death, relieved the Aβ25-35‑induced increase in intracellular Zn2+ and Ca2+ concentrations; reversed the Aβ25-35‑induced increase in ROS content, the Aβ25-35‑induced increase in the L-ICa peak amplitude at different membrane potentials, the Aβ25-35‑induced the dysfunction of the mitochondria and lysosomes, and the Aβ25-35‑induced decrease in ZnT-3 and MT-3 mRNA expressions; and increased the Cav1.2 mRNA expression in the hippocampal neurons. These results suggest that TPEN, the Zn2+-specific chelator, attenuated Aβ25-35‑induced neuronal damage, correlating with the recovery of intracellular Zn2+ and modulation of abnormal Ca2+-related signaling pathways.
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Affiliation(s)
- Wen-Bo Chen
- College of Life Sciences, Nankai University, Tianjin, 300071, China
- School of Basic Medical Science, Henan University, Kaifeng, 475004, China
| | - Yu-Xiang Wang
- Department of Immunology and Pathogenic Biology, School of Basic Medical Sciences, Hebei University of Chinese Medicine, Shijiazhuang, 050200, Hebei, China
| | - Hong-Gang Wang
- College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Di An
- College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Dan Sun
- College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Pan Li
- Tianjin Key Laboratory of Cerebral Vascular and Neurodegenerative Diseases, Tianjin Neurosurgery Institute, Department of Neurology, Tianjin Huanhu Hospital Affiliated to Nankai University, Tianjin, China
| | - Tao Zhang
- College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Wan-Ge Lu
- College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Yan-Qiang Liu
- College of Life Sciences, Nankai University, Tianjin, 300071, China.
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Miao Y, Zhao GL, Cheng S, Wang Z, Yang XL. Activation of retinal glial cells contributes to the degeneration of ganglion cells in experimental glaucoma. Prog Retin Eye Res 2023; 93:101169. [PMID: 36736070 DOI: 10.1016/j.preteyeres.2023.101169] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 01/12/2023] [Accepted: 01/24/2023] [Indexed: 02/04/2023]
Abstract
Elevation of intraocular pressure (IOP) is a major risk factor for neurodegeneration in glaucoma. Glial cells, which play an important role in normal functioning of retinal neurons, are well involved into retinal ganglion cell (RGC) degeneration in experimental glaucoma animal models generated by elevated IOP. In response to elevated IOP, mGluR I is first activated and Kir4.1 channels are subsequently inhibited, which leads to the activation of Müller cells. Müller cell activation is followed by a complex process, including proliferation, release of inflammatory and growth factors (gliosis). Gliosis is further regulated by several factors. Activated Müller cells contribute to RGC degeneration through generating glutamate receptor-mediated excitotoxicity, releasing cytotoxic factors and inducing microglia activation. Elevated IOP activates microglia, and following morphological and functional changes, these cells, as resident immune cells in the retina, show adaptive immune responses, including an enhanced release of pro-inflammatory factors (tumor neurosis factor-α, interleukins, etc.). These ATP and Toll-like receptor-mediated responses are further regulated by heat shock proteins, CD200R, chemokine receptors, and metabotropic purinergic receptors, may aggravate RGC loss. In the optic nerve head, astrogliosis is initiated and regulated by a complex reaction process, including purines, transmitters, chemokines, growth factors and cytokines, which contributes to RGC axon injury through releasing pro-inflammatory factors and changing extracellular matrix in glaucoma. The effects of activated glial cells on RGCs are further modified by the interplay among different types of glial cells. This review is concluded by presenting an in-depth discussion of possible research directions in this field in the future.
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Affiliation(s)
- Yanying Miao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Guo-Li Zhao
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Shuo Cheng
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China
| | - Zhongfeng Wang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
| | - Xiong-Li Yang
- State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, 200032, China.
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Chen C, Fan P, Zhang L, Xue K, Hu J, Huang J, Lu W, Xu J, Xu S, Qiu G, Ran J, Gan S. Bumetanide Rescues Aquaporin-4 Depolarization via Suppressing β-Dystroglycan Cleavage and Provides Neuroprotection in Rat Retinal Ischemia-Reperfusion Injury. Neuroscience 2023; 510:95-108. [PMID: 36493910 DOI: 10.1016/j.neuroscience.2022.11.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 11/21/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022]
Abstract
Aquaporin-4 (AQP4) regulates retinal water homeostasis and participates in retinal oedema pathophysiology. β-dystroglycan (β-DG) is responsible for AQP4 polarization and can be cleaved by matrix metalloproteinase-9 (MMP9). Retinal oedema induced by ischemia-reperfusion (I/R) injury is an early complication. Bumetanide (BU) has potential efficacy against cytotoxic oedema. Our study investigated the effects of β-DG cleavage on AQP4 and the roles of BU in a rat retinal I/R injury model. The model was induced by applying 110 mm Hg intraocular pressure to the anterior eye chamber. BU and U0126 (a selective ERK inhibitor) were intraperitoneally administered 15 and 30 min, respectively, before I/R induction. Rhodamine isothiocyanate extravasation detection, quantitative real-time PCR, transmission electron microscopy, hematoxylin-eosin staining, immunofluorescence staining, western blotting, and TUNEL staining were performed. AQP4 lost its polarization in the retinal perivascular domain as a result of β-DG cleavage. BU rescued AQP4 depolarization, suppressed AQP4 protein expression, attenuated retinal cytotoxic oedema, and downregulated β-DG and AQP4 mRNA expression. BU suppressed glial responses and mitochondria-mediated apoptotic protein expression, including that of Caspase-3 and Cyto C, raised the Bcl-2/Bax ratio, and lowered the number of apoptotic cells in the retina. Both BU and U0126 downregulated p-ERK and MMP9 expression. Thus, BU treatment suppressed β-DG cleavage, recovered AQP4 polarization partially via inhibiting ERK/MMP9 signaling pathway, and possess potential neuroprotective efficacy in the rat retinal ischemia-reperfusion injury model.
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Affiliation(s)
- Chunyan Chen
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Ping Fan
- Department of Gynecology and Obstetrics of The Fifth People's Hospital of Chongqing, PR China
| | - Lirong Zhang
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Kaige Xue
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Jiaheng Hu
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Juan Huang
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Weitian Lu
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Jin Xu
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Shiye Xu
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Guoping Qiu
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Jianhua Ran
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China
| | - Shengwei Gan
- Institute of Neuroscience, Basic Medicine College of Chongqing Medical University, Chongqing, PR China.
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Nsiah NY, Inman DM. Destabilizing COXIV in Müller Glia Increases Retinal Glycolysis and Alters Scotopic Electroretinogram. Cells 2022; 11:cells11233756. [PMID: 36497016 PMCID: PMC9737073 DOI: 10.3390/cells11233756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/17/2022] [Accepted: 11/22/2022] [Indexed: 11/25/2022] Open
Abstract
Müller glia (MG), the principal glial cell of the retina, have a metabolism that defies categorization into glycolytic versus oxidative. We showed that MG mount a strong hypoxia response to ocular hypertension, raising the question of their relative reliance on mitochondria for function. To explore the role of oxidative phosphorylation (OXPHOS) in MG energy production in vivo, we generated and characterized adult mice in which MG have impaired cytochrome c oxidase (COXIV) activity through knockout of the COXIV constituent COX10. Histochemistry and protein analysis showed that COXIV protein levels were significantly lower in knockout mouse retina compared to control. Loss of COXIV activity in MG did not induce structural abnormalities, though oxidative stress was increased. Electroretinography assessment showed that knocking out COX10 significantly impaired scotopic a- and b-wave responses. Inhibiting mitochondrial respiration in MG also altered the retinal glycolytic profile. However, blocking OXPHOS in MG did not significantly exacerbate retinal ganglion cell (RGC) loss or photopic negative response after ocular hypertension (OHT). These results suggest that MG were able to compensate for reduced COXIV stability by maintaining fundamental processes, but changes in retinal physiology and metabolism-associated proteins indicate subtle changes in MG function.
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Walch E, Fiacco TA. Honey, I shrunk the extracellular space: Measurements and mechanisms of astrocyte swelling. Glia 2022; 70:2013-2031. [PMID: 35635369 PMCID: PMC9474570 DOI: 10.1002/glia.24224] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/17/2022] [Accepted: 05/17/2022] [Indexed: 12/16/2022]
Abstract
Astrocyte volume fluctuation is a physiological phenomenon tied closely to the activation of neural circuits. Identification of underlying mechanisms has been challenging due in part to use of a wide range of experimental approaches that vary between research groups. Here, we first review the many methods that have been used to measure astrocyte volume changes directly or indirectly. While the field has recently shifted towards volume analysis using fluorescence microscopy to record cell volume changes directly, established metrics corresponding to extracellular space dynamics have also yielded valuable insights. We then turn to analysis of mechanisms of astrocyte swelling derived from many studies, with a focus on volume changes tied to increases in extracellular potassium concentration ([K+ ]o ). The diverse methods that have been utilized to generate the external [K+ ]o environment highlight multiple scenarios of astrocyte swelling mediated by different mechanisms. Classical potassium buffering theories are tempered by many recent studies that point to different swelling pathways optimized at particular [K+ ]o and that depend on local/transient versus more sustained increases in [K+ ]o .
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Affiliation(s)
- Erin Walch
- Division of Biomedical Sciences, School of MedicineUniversity of California, RiversideRiversideCaliforniaUSA
| | - Todd A. Fiacco
- Department of Molecular, Cell and Systems BiologyUniversity of California, RiversideRiversideCaliforniaUSA
- Center for Glial‐Neuronal InteractionsUniversity of California, RiversideRiversideCaliforniaUSA
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Diabetic Macular Edema: Current Understanding, Molecular Mechanisms and Therapeutic Implications. Cells 2022; 11:cells11213362. [PMID: 36359761 PMCID: PMC9655436 DOI: 10.3390/cells11213362] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/19/2022] [Accepted: 10/20/2022] [Indexed: 11/24/2022] Open
Abstract
Diabetic retinopathy (DR), with increasing incidence, is the major cause of vision loss and blindness worldwide in working-age adults. Diabetic macular edema (DME) remains the main cause of vision impairment in diabetic patients, with its pathogenesis still not completely elucidated. Vascular endothelial growth factor (VEGF) plays a pivotal role in the pathogenesis of DR and DME. Currently, intravitreal injection of anti-VEGF agents remains as the first-line therapy in DME treatment due to the superior anatomic and functional outcomes. However, some patients do not respond satisfactorily to anti-VEGF injections. More than 30% patients still exist with persistent DME even after regular intravitreal injection for at least 4 injections within 24 weeks, suggesting other pathogenic factors, beyond VEGF, might contribute to the pathogenesis of DME. Recent advances showed nearly all the retinal cells are involved in DR and DME, including breakdown of blood-retinal barrier (BRB), drainage dysfunction of Müller glia and retinal pigment epithelium (RPE), involvement of inflammation, oxidative stress, and neurodegeneration, all complicating the pathogenesis of DME. The profound understanding of the changes in proteomics and metabolomics helps improve the elucidation of the pathogenesis of DR and DME and leads to the identification of novel targets, biomarkers and potential therapeutic strategies for DME treatment. The present review aimed to summarize the current understanding of DME, the involved molecular mechanisms, and the changes in proteomics and metabolomics, thus to propose the potential therapeutic recommendations for personalized treatment of DME.
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Marshall AT, Crewther SG. Osmotic gradients and transretinal water flow-a quantitative elemental microanalytical study of frozen hydrated chick eyes. Front Cell Neurosci 2022; 16:975313. [PMID: 36353149 PMCID: PMC9639504 DOI: 10.3389/fncel.2022.975313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 10/03/2022] [Indexed: 08/30/2023] Open
Abstract
Optical clarity and efficient phototransduction are necessary for optimal vision, however, how the associated processes of osmoregulation and continuous fluid drainage across the whole eye are achieved remains relatively unexplored. Hence, we have employed elemental microanalysis of planed surfaces of light-adapted bulk frozen-hydrated chick eyes to determine the unique intracellular elemental localization, compositions, and hydration states that contribute to maintaining osmotic gradients and water flow from the vitreous, across the retina, retinal pigment epithelium (RPE), to choroid and sclera. As expected, the greatest difference in resultant osmotic concentration gradients, [calculated using the combined concentrations of sodium (Na) and potassium (K)] and tissue hydration [oxygen-defined water concentration], occurs in the outer retina and, in particular, in the RPE where the apical and basal membranes are characterized by numerous bioenergetically active, osmoregulating ion transport mechanisms, aquaporins, and chloride (Cl) channels. Our results also demonstrate that the high intracellular Na+ and K+ concentrations in the apical region of the RPE are partially derived from the melanosomes. The inclusion of the ubiquitous osmolyte taurine to the calculation of the osmotic gradients suggests a more gradual increase in the osmotic transport of water from the vitreous into the ganglion cell layer across the inner retina to the outer segments of the photoreceptor/apical RPE region where the water gradient increases rapidly towards the basal membrane. Thus transretinal water is likely to cross the apical membrane from the retina into the RPE cells down the Na+ and K+ derived osmotic concentration gradient and leave the RPE for the choroid across the basal membrane down the Cl- derived osmotic concentration gradient that is sustained by the well-described bioenergetically active RPE ion transporters and channels.
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Affiliation(s)
- Alan T. Marshall
- Analytical Electron Microscopy Laboratory, Department of Genetics and Environment, La Trobe University, Melbourne, VIC, Australia
| | - Sheila G. Crewther
- Department of Psychology and Counselling, La Trobe University, Melbourne, VIC, Australia
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10
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Insight into the Mammalian Aquaporin Interactome. Int J Mol Sci 2022; 23:ijms23179615. [PMID: 36077012 PMCID: PMC9456110 DOI: 10.3390/ijms23179615] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 08/16/2022] [Accepted: 08/22/2022] [Indexed: 01/07/2023] Open
Abstract
Aquaporins (AQPs) are a family of transmembrane water channels expressed in all living organisms. AQPs facilitate osmotically driven water flux across biological membranes and, in some cases, the movement of small molecules (such as glycerol, urea, CO2, NH3, H2O2). Protein-protein interactions play essential roles in protein regulation and function. This review provides a comprehensive overview of the current knowledge of the AQP interactomes and addresses the molecular basis and functional significance of these protein-protein interactions in health and diseases. Targeting AQP interactomes may offer new therapeutic avenues as targeting individual AQPs remains challenging despite intense efforts.
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Iovino C, Au A, Ramtohul P, Bacci T, AlBahlal A, Khan AM, Al-Abdullah AA, Wendel R, Chhablani J, Sadda S, Freund KB, Sarraf D. Coincident PAMM and AMN and Insights Into a Common Pathophysiology. Am J Ophthalmol 2022; 236:136-146. [PMID: 34283978 DOI: 10.1016/j.ajo.2021.07.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 06/29/2021] [Accepted: 07/06/2021] [Indexed: 11/01/2022]
Abstract
PURPOSE To analyze imaging characteristics and the clinical course of patients demonstrating coincident lesions of paracentral acute middle maculopathy (PAMM) and acute macular neuroretinopathy (AMN) in the same eye. DESIGN Retrospective, observational case series. METHODS Lesions from patients presenting with coincident PAMM and AMN in the same eye were evaluated with multimodal imaging including optical coherence tomography (OCT). The association with ocular and systemic findings was also investigated. RESULTS Fifteen subjects (17 eyes) were included in the study. The mean age was 44.4 ± 15.3 years and the follow-up period ranged from 1 to 32 weeks (mean, 11.9 ± 11.4 weeks). The mean visual acuity was 0.8 ± 0.6 logarithm of minimal angle of resolution (Snellen equivalent 20/126) at baseline and 0.3 ± 0.4 logarithm of minimal angle of resolution (Snellen equivalent 20/40) at the last follow-up. PAMM and AMN lesions occurred in the setting of Purtscher's retinopathy (4 eyes, 3 patients), retinal vein occlusion (7 eyes, 7 patients), central retinal artery occlusion (1 eye, 1 patient), and idiopathic retinal vasculitis (1 eye, 1 patient). In 4 eyes (3 patients), an association with other ocular disorders was not identified as evaluated with multimodal imaging. Of the total cohort, 11 eyes (64.7%) showed extension of the AMN hyperreflective bands in Henle's fiber layer with a Z-shaped morphology on OCT B-scan. CONCLUSIONS The presence of coincident PAMM and AMN suggests a common pathophysiologic etiology. This may be the result of retinal vein impairment and hypoperfusion at the level of the deep retinal capillary plexus possibly leading to injury to the Müller glia or photoreceptors in Henle's fiber layer.
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Keilhoff G, Titze M, Ebmeyer U. Immuno-histological detection of resistant columnar units and vulnerable networks in the rat retina after asphyxia-induced transient cardiac arrest. Restor Neurol Neurosci 2021; 39:267-289. [PMID: 34334436 DOI: 10.3233/rnn-211174] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Stroke-related loss of vision is one of the residual impairments, restricting the quality of life. However, studies of the ocular manifestations of asphyxia cardiac arrest/resuscitation (ACA/R) have reported very heterogeneous results. OBJECTIVE We aimed to evaluate the ACA/R-induced degeneration pattern of the different retinal cell populations in rats using different immuno-histological stainings. METHODS The staining pattern of toluidine blue and the ganglion cell markers β-III-tubulin and NeuN; the calcium-binding protein parvalbumin, indicating ganglion, amacrine, and horizontal cells; calretinin D28k, indicating ganglion and amacrine cells; calbindin, indicating horizontal cells; Chx 10, indicating cone bipolar cells; PKCα, indicating ON-type rod bipolar cells; arrestin, indicating cones; and rhodopsin, a marker of rods, as well as the glial cell markers GFAP (indicating astroglia and Müller cells) and IBA1 (indicating microglia), were evaluated after survival times of 7 and 21 days in an ACA/R rat model. Moreover, quantitative morphological analysis of the optic nerve was performed. The ACA/R specimens were compared with those from sham-operated and completely naïve rats. RESULTS ACA/R-induced effects were: (i) a significant reduction of retinal thickness after long-term survival; (ii) ganglion cell degeneration, including their fiber network in the inner plexiform layer; (iii) degeneration of amacrine and cone bipolar cells; (iv) degeneration of cone photoreceptors; (v) enhanced resistance to ACA/R by rod photoreceptors, ON-type rod bipolar and horizontal cells, possibly caused by the strong upregulation of the calcium-binding proteins calretinin, parvalbumin, and calbindin, counteracting the detrimental calcium overload; (vi) significant activation of Müller cells as further element of retinal anti-stress self-defense mechanisms; and (vii) morphological alterations of the optic nerve in form of deformed fibers. CONCLUSIONS Regardless of the many defects, the surviving neuronal structures seemed to be able to maintain retinal functionality, which can be additionally improved by regenerative processes true to the "use it or lose it" dogma.
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Affiliation(s)
- Gerburg Keilhoff
- Institute of Biochemistry and Cell Biology, Medical Faculty, University of Magdeburg, Magdeburg, Germany
| | - Maximilian Titze
- Institute of Biochemistry and Cell Biology, Medical Faculty, University of Magdeburg, Magdeburg, Germany
| | - Uwe Ebmeyer
- Department of Anesthesiology, Medical Faculty, University of Magdeburg, Magdeburg, Germany
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13
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Francone A, Govetto A, Yun L, Essilfie J, Nouri-Mahdavi K, Sarraf D, Hubschman JP. Evaluation of non-exudative microcystoid macular abnormalities secondary to retinal vein occlusion. Graefes Arch Clin Exp Ophthalmol 2021; 259:3579-3588. [PMID: 34155562 PMCID: PMC8589792 DOI: 10.1007/s00417-021-05250-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 05/10/2021] [Accepted: 05/14/2021] [Indexed: 11/16/2022] Open
Abstract
Purpose We aimed to investigate non-exudative microcystoid macular abnormalities for visual and anatomical outcome in patients with retinal vein occlusion (RVO) with and without glaucomatous optic neuropathy (GON). Methods Medical records of 124 eyes (105 patients) with RVO were reviewed and analyzed. Eyes demonstrating microcystoid macular abnormalities were divided into 2 groups, those with evidence of glaucoma (group A) and those without glaucoma (group B). Best-corrected visual acuity (BCVA), the prevalence and number of microcystoid macular abnormalities, and number of intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections were compared at baseline and follow-up. Results Seventy-one out of 105 eyes (67.6%) with RVO displayed microcystoid macular abnormalities. Thirty-eight out of 71 eyes (53.5%) presented with concomitant glaucoma (group A), while the remaining 33 eyes (42.6%) had no history of glaucoma (group B). At the end of the follow-up period, mean BCVA was worse in group A versus group B (20/80 versus 20/40, respectively; p = .003). The mean number of anti-VEGF injections was 10.1 ± 9.2 in group A versus 5.9 ± 6.9 in group B (p = .03). Conclusion Eyes with RVO and concomitant glaucoma exhibited a significantly higher number of microcystoid macular abnormalities and worse BCVA versus eyes with RVO without glaucoma.
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Affiliation(s)
- Anibal Francone
- Retina Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA, USA
| | - Andrea Govetto
- Ophthalmology Department, Fatebenefratelli-Oftalmico Hospital, Milan, Italy
| | - Lisa Yun
- Retina Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA, USA
| | - Juliet Essilfie
- Retina Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA, USA
| | - Kouros Nouri-Mahdavi
- Glaucoma Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA, USA
| | - David Sarraf
- David Geffen School of Medicine At UCLA, Retinal Disorders and Ophthalmic Genetics Division, Stein Eye Institute, Los Angeles, CA, USA.,Greater Los Angeles VA Healthcare Center, Los Angeles, CA, USA
| | - Jean-Pierre Hubschman
- Retina Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA, USA.
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14
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Ye SS, Tang Y, Song JT. ATP and Adenosine in the Retina and Retinal Diseases. Front Pharmacol 2021; 12:654445. [PMID: 34211393 PMCID: PMC8239296 DOI: 10.3389/fphar.2021.654445] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Accepted: 05/25/2021] [Indexed: 12/11/2022] Open
Abstract
Extracellular ATP and its ultimate degradation product adenosine are potent extracellular signaling molecules that elicit a variety of pathophysiological pathways in retina through the activation of P2 and P1 purinoceptors, respectively. Excessive build-up of extracellular ATP accelerates pathologic responses in retinal diseases, whereas accumulation of adenosine protects retinal cells against degeneration or inflammation. This mini-review focuses on the roles of ATP and adenosine in three types of blinding diseases including age-related macular degeneration (AMD), glaucoma, and diabetic retinopathy (DR). Several agonists and antagonists of ATP receptors and adenosine receptors (ARs) have been developed for the potential treatment of glaucoma, DR and AMD: antagonists of P2X7 receptor (P2X7R) (BBG, MRS2540) prevent ATP-induced neuronal apoptosis in glaucoma, DR, and AMD; A1 receptor (A1R) agonists (INO-8875) lower intraocular pressure in glaucoma; A2A receptor (A2AR) agonists (CGS21680) or antagonists (SCH58261, ZM241385) reduce neuroinflammation in glaucoma, DR, and AMD; A3 receptor (A3R) agonists (2-Cl-lB-MECA, MRS3558) protect retinal ganglion cells (RGCs) from apoptosis in glaucoma.
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Affiliation(s)
- Shan-Shan Ye
- Eye Hospital, China Academy of Chinese Medical Sciences, Beijing, China
| | - Yong Tang
- International Collaborative Centre on Big Science Plan for Purinergic Signalling, Chengdu University of Traditional Chinese Medicine, Chengdu, China.,Acupuncture and Chronobiology Key Laboratory of Sichuan Province, Chengdu, China
| | - Jian-Tao Song
- Eye Hospital, China Academy of Chinese Medical Sciences, Beijing, China
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15
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Wang T, Zhang C, Xie H, Jiang M, Tian H, Lu L, Xu GT, Liu L, Zhang J. Anti-VEGF therapy prevents Müller intracellular edema by decreasing VEGF-A in diabetic retinopathy. EYE AND VISION 2021; 8:13. [PMID: 33865457 PMCID: PMC8053282 DOI: 10.1186/s40662-021-00237-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 03/18/2021] [Indexed: 02/07/2023]
Abstract
Background Although vascular endothelial growth factor A (VEGF-A) is known to play a key role in causing retinal edema, whether and how VEGF-A induces intracellular edema in the retina still remains unclear. Methods Sprague-Dawley rats were rendered diabetic with intraperitoneal injection of streptozotocin. Intravitreal injection of ranibizumab was performed 8 weeks after diabetes onset. rMC-1 cells (rat Müller cell line) were treated with glyoxal for 24 h with or without ranibizumab. The expression levels of inwardly rectifying K+ channel 4.1 (Kir4.1), aquaporin 4 (AQP4), Dystrophin 71 (Dp71), VEGF-A, glutamine synthetase (GS) and sodium-potassium-ATPase (Na+-K+-ATPase) were examined using Western blot. VEGF-A in the supernatant of the cell culture was detected with ELISA. The intracellular potassium and sodium levels were detected with specific indicators. Results Compared with normal control, protein expressions of Kir4.1 and AQP4 were down-regulated significantly in diabetic rat retinas, which were prevented by ranibizumab. The above changes were recapitulated in vitro. Similarly, the intracellular potassium level in glyoxal-treated rMC-1 cells was increased, while the intracellular sodium level and Na+-K+-ATPase protein level remained unchanged, compared with control. However, ranibizumab treatment decreased intracellular sodium, but not potassium. Conclusion Ranibizumab protected Müller cells from diabetic intracellular edema through the up-regulation of Kir4.1 and AQP4 by directly binding VEGF-A. It also caused a reduction in intracellular osmotic pressure.
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Affiliation(s)
- Tianqin Wang
- Department of Ophthalmology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, 160 Pujian Road, Pudong New District, Shanghai, 200127, China
| | - Chaoyang Zhang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, 100 Haining Road, Hongkou District, Shanghai, 200080, China.,National Clinical Research Center for Eye Diseases; Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Hai Xie
- Tongji Eye Institute, Tongji University School of Medicine, 1239 Siping Road, Medical School Building, Room 623, Shanghai, 200092, China
| | - Mengmeng Jiang
- Department of Ophthalmology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, 160 Pujian Road, Pudong New District, Shanghai, 200127, China
| | - Haibin Tian
- Tongji Eye Institute, Tongji University School of Medicine, 1239 Siping Road, Medical School Building, Room 623, Shanghai, 200092, China
| | - Lixia Lu
- Tongji Eye Institute, Tongji University School of Medicine, 1239 Siping Road, Medical School Building, Room 623, Shanghai, 200092, China
| | - Guo-Tong Xu
- Tongji Eye Institute, Tongji University School of Medicine, 1239 Siping Road, Medical School Building, Room 623, Shanghai, 200092, China.
| | - Lin Liu
- Department of Ophthalmology, Renji Hospital, Shanghai Jiao Tong University School of Medicine, 160 Pujian Road, Pudong New District, Shanghai, 200127, China.
| | - Jingfa Zhang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, 100 Haining Road, Hongkou District, Shanghai, 200080, China. .,National Clinical Research Center for Eye Diseases; Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China.
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16
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Chen Z, Yang Z, Li X, Wang H, Wang Y, Ding C, Yang J, Ni N, Mei Y, Zhang S. microRNA-320a prevent Müller cells from hypoxia injury by targeting aquaporin-4. J Cell Biochem 2020; 121:4711-4723. [PMID: 32830348 DOI: 10.1002/jcb.29524] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 10/08/2019] [Indexed: 12/15/2022]
Abstract
Müller cells are closely related to diabetic retinopathy (DR). Aquaporin-4 (AQP4) can effectively promote the diffusion of water across cellular membranes. However, the dynamic balance of water plays key role in many diseases, such as cerebral edema. Meanwhile, the unusual expression and distribution of AQP4 in the retina are the significant causes of ocular hypertension and reperfusion injury. To explore the functional significance between microRNA-320a (miR-320a) and AQP4 in pathological hypoxia-induced DR related retinal edema, we hypothesized that miR-320a regulates AQP4 expression and internalization to relieve the edema of Müller cells under the pathological retinal hypoxia stress by targeting AQP4, thereby attenuate the damage of Müller cells. Results demonstrated that miR-320a mimics inhibited the expressions of AQP4 in Müller cells. Furthermore, overexpression miR-320a protected Müller cells by suppressing superoxide anion. In addition, overexpression miR-320a markedly attenuated hypoxia-induced injury, significantly increased the cell viability, and promoted the internalization of AQP4. Furthermore, miR-320a can also regulate the stable anchoring of AQP4 on the cell membrane. Our study indicated that miR-320a may be a potential modulator which can mediate AQP4 expression and attenuate the hypoxia damage of Müller cells. In conclusion, miR-320a may be a potential target for DR therapy by targeting AQP4.
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Affiliation(s)
- Zhen Chen
- Department of Ophthalmology, The First People's Hospital of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Research Center of Fundus Disease of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Kunming University of Science and Technology Affiliated Hospital, Kunming, Yunnan, China
- Medical college, Kunming University of Science and Technology, Kunming, Yunnan, China
- Department of Ophthalmology, Dali University, Dali, Yunnan, China
| | - Zhengrong Yang
- Department of Ophthalmology, The First People's Hospital of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Research Center of Fundus Disease of Yunnan, Kunming, Yunnan, China
| | - Xiaoliang Li
- Department of Ophthalmology, The First People's Hospital of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Research Center of Fundus Disease of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Kunming University of Science and Technology Affiliated Hospital, Kunming, Yunnan, China
- Medical college, Kunming University of Science and Technology, Kunming, Yunnan, China
| | - He Wang
- Department of Ophthalmology, The First People's Hospital of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Research Center of Fundus Disease of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Kunming University of Science and Technology Affiliated Hospital, Kunming, Yunnan, China
| | - Yonggang Wang
- Department of Ophthalmology, The First People's Hospital of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Research Center of Fundus Disease of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Kunming University of Science and Technology Affiliated Hospital, Kunming, Yunnan, China
| | - Chao Ding
- Department of Ophthalmology, The First People's Hospital of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Research Center of Fundus Disease of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Kunming University of Science and Technology Affiliated Hospital, Kunming, Yunnan, China
| | - JingYing Yang
- Department of Ophthalmology, The First People's Hospital of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Research Center of Fundus Disease of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Kunming University of Science and Technology Affiliated Hospital, Kunming, Yunnan, China
| | - Ninghua Ni
- Department of Ophthalmology, The First People's Hospital of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Research Center of Fundus Disease of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Kunming University of Science and Technology Affiliated Hospital, Kunming, Yunnan, China
| | - Yan Mei
- Department of Ophthalmology, The First People's Hospital of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Research Center of Fundus Disease of Yunnan, Kunming, Yunnan, China
- Department of Ophthalmology, Kunming University of Science and Technology Affiliated Hospital, Kunming, Yunnan, China
- Medical college, Kunming University of Science and Technology, Kunming, Yunnan, China
- Department of Ophthalmology, Dali University, Dali, Yunnan, China
| | - Shiwen Zhang
- Head and Neck Surgery, The Third Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China
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17
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Spectral domain optical coherence tomography classification of diabetic macular edema: a new proposal to clinical practice. Graefes Arch Clin Exp Ophthalmol 2020; 258:1165-1172. [PMID: 32152718 DOI: 10.1007/s00417-020-04640-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 02/05/2020] [Accepted: 02/25/2020] [Indexed: 12/14/2022] Open
Abstract
PURPOSE To classify the types of diabetic macular edema (DME) and evaluate its morphological features on spectral domain optical coherence tomography (SD-OCT) and determine correlations between visual acuity and OCT findings. METHODS We assessed 406 eyes of 309 patients with a diagnosis of DME retrospectively. Three types based on SD-OCT were identified: diffuse macular edema, cystoid macular edema, and cystoid degeneration. Morphological features such as serous macular detachment (SMD), vitreomacular interface abnormalities (VMAI), hard exudates, photoreceptor status, and correlations between visual acuity and those morphological features were also evaluated by SD-OCT. RESULTS The most common type of DME was cystoid edema (68.5%). No statistically significant difference was found between groups in sex (P = 0.40), type of diabetes (P = 0.50), or diabetic retinopathy (P = 0.78). However, the duration of symptoms and BCVA was significantly lower in the group with cystoid degeneration compared with the group with cystoid edema (P < 0.001) and the group with diffuse macular edema (P < 0.001). In the group with cystoid degeneration compared with the groups with cystoid and diffuse edema, the central fovea and central subfield were significantly thicker (both (P < 0.001), the subfoveal choroid was significantly thinner (P = 0.049), rate of serous macular detachment was significantly lower (P < 0.001), and the rate of outer retinal damage was significantly higher (P < 0.001). CONCLUSIONS Cystoid macular degeneration, which is consistent with poor functional and morphological outcomes, should be differentiated from cystoid macular edema. Serous macular detachment, which is mostly seen in eyes with early stages of DME, should be evaluated as an accompanying morphological finding rather than a type of DME.
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18
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Ma M, Zhao S, Zhang J, Sun T, Fan Y, Zheng Z. High Glucose-Induced TRPC6 Channel Activation Decreases Glutamate Uptake in Rat Retinal Müller Cells. Front Pharmacol 2020; 10:1668. [PMID: 32116675 PMCID: PMC7033573 DOI: 10.3389/fphar.2019.01668] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 12/20/2019] [Indexed: 12/15/2022] Open
Abstract
High glucose (HG) increases the production of reactive oxygen species (ROS), leading to decreased glutamate uptake in Müller cells. The transient receptor potential cation channel 6 (TRPC6) channel, an oxidative stress-sensitive Ca2+-permeable cationic channel, is readily detected in Müller cells and highly expressed under HG conditions. Yet, the effect of high glucose-induced TRPC6 channel activation in Müller cells is poorly understood. We hypothesized that TRPC6 channel activation mediates high glucose-induced decreases in Müller cell glutamate uptake. We found RNA interference (RNAi) of the TRPC6 channel abolished HG-induced decreases in glutamate uptake and cell death. HG also decreased the expression of the glutamate-aspartate transporter (GLAST), which is the most important transporter involved in glutamate uptake. The mRNA level of ciliary neurotrophic factor (CNTF) in rMC-1 cells and the release of CNTF in the culture media was decreased, but the mRNA levels of IL-6 and vascular endothelial growth factor (VEGF) were increased under HG conditions. After RNAi silencing in rMC-1 cells, the mRNA levels of CNTF increased, but IL-6 and VEGF levels decreased. Furthermore, TRPC6 knockdown (KD) decreased expression of glial fibrillary acidic protein (GFAP) and increased expression of Kir4.1, pointing to inhibition of HG-induced gliosis in rMC-1 cells. ROS and intracellular Ca2+ levels decreased after TRPC6 knockdown. Exposure to Hyp9 (10 μM), a highly selective TRPC6 channel agonist, can aggravate HG-induced pathological changes. Collectively, our results suggest TRPC6 channel activation is involved in HG-induced decreases in glutamate uptake in rMC-1 cells. These findings provide novel insights into the role of TRPC6 in HG-induced retinal neurovasculopathy and suggest TRPC6 is a promising target for drug development for diabetic retinopathy (DR).
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Affiliation(s)
- Mingming Ma
- Department of Ophthalmology, Shanghai General Hospital, Shanghai, China.,National Clinical Research Center for Eye Diseases, Shanghai, China.,Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Shuzhi Zhao
- Department of Ophthalmology, Shanghai General Hospital, Shanghai, China.,National Clinical Research Center for Eye Diseases, Shanghai, China.,Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Jian Zhang
- Department of Ophthalmology, Shanghai General Hospital, Shanghai, China.,National Clinical Research Center for Eye Diseases, Shanghai, China.,Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Tao Sun
- Department of Ophthalmology, Shanghai General Hospital, Shanghai, China.,National Clinical Research Center for Eye Diseases, Shanghai, China.,Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Ying Fan
- Department of Ophthalmology, Shanghai General Hospital, Shanghai, China.,National Clinical Research Center for Eye Diseases, Shanghai, China.,Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
| | - Zhi Zheng
- Department of Ophthalmology, Shanghai General Hospital, Shanghai, China.,National Clinical Research Center for Eye Diseases, Shanghai, China.,Shanghai Key Laboratory of Ocular Fundus Diseases, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Engineering Center for Precise Diagnosis and Treatment of Eye Diseases, Shanghai, China
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19
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Ghaseminejad F, Kaplan L, Pfaller AM, Hauck SM, Grosche A. The role of Müller cell glucocorticoid signaling in diabetic retinopathy. Graefes Arch Clin Exp Ophthalmol 2019; 258:221-230. [PMID: 31734719 DOI: 10.1007/s00417-019-04521-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/14/2019] [Accepted: 10/22/2019] [Indexed: 12/13/2022] Open
Abstract
Diabetic retinopathy (DR) is a sight-threatening complication associated with the highly prevalent diabetes disorder. Both the microvascular damage and neurodegeneration detected in the retina caused by chronic hyperglycemia have brought special attention to Müller cells, the major macroglia of the retina that are responsible for retinal homeostasis. Given the role of glucocorticoid signaling in anti-inflammatory responses and the almost exclusive expression of glucocorticoid receptors (GRs) in retinal Müller cells, administration of corticosteroid agonists as a potential treatment option has been widely studied. Although these approaches have been moderately efficacious in treating or de-escalating DR pathomechanisms, there are various side effects and gaps of knowledge with regard to introducing exogenous glucocorticoids to the diseased retina. In this paper, we provide a review of the literature concerning the available evidence for the role of Müller cell glucocorticoid signaling in DR and we discuss previously investigated approaches in modulating this system as possible treatment options. Furthermore, we propose a novel alternative to the available choices of treatment by using gene therapy as a tool to regulate the expression of GR in retinal Müller cells. Upregulating GR expression allows for induced glucocorticoid signaling with more enduring effects compared to injection of agonists. Hence, repetitive injections would no longer be required. Lastly, side effects of glucocorticoid therapy such as glucocorticoid resistance of GR following chronic exposure to excess ligands or agonists can be avoided.
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Affiliation(s)
- Farhad Ghaseminejad
- Department of Physiological Genomics, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, Martinsried, Germany
| | - Lew Kaplan
- Department of Physiological Genomics, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, Martinsried, Germany
| | - Anna M Pfaller
- Department of Physiological Genomics, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, Martinsried, Germany
| | - Stefanie M Hauck
- Research Unit Protein Science, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Heidemannstr. 1, Neuherberg, Germany
| | - Antje Grosche
- Department of Physiological Genomics, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, Martinsried, Germany.
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20
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Toft-Bertelsen TL, Larsen BR, MacAulay N. Sensing and regulation of cell volume - we know so much and yet understand so little: TRPV4 as a sensor of volume changes but possibly without a volume-regulatory role? Channels (Austin) 2019; 12:100-108. [PMID: 29424275 PMCID: PMC5972811 DOI: 10.1080/19336950.2018.1438009] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Cellular volume changes lead to initiation of cell volume regulatory events, the molecular identity of which remains unresolved. We here discuss experimental challenges associated with investigation of volume regulation during application of large, non-physiological osmotic gradients. The TRPV4 ion channel responds to volume increase irrespectively of the molecular mechanism underlying cell swelling, and is thus considered a sensor of volume changes. Evidence pointing towards the involvement of TRPV4 in subsequent volume regulatory mechanisms is intriguing, yet far from conclusive. We here present an experimental setting with astrocytic cell swelling in the absence of externally applied osmotic gradients, and the lack of evidence for involvement of TRPV4 in this regulatory volume response. Our aim with these new data and the preceding discussion is to stimulate further experimental effort in this area of research to clarify the role of TRPV4 and other channels and transporters in regulatory volume responses.
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Affiliation(s)
| | - Brian R Larsen
- a Department of Neuroscience , University of Copenhagen , Copenhagen , Denmark
| | - Nanna MacAulay
- a Department of Neuroscience , University of Copenhagen , Copenhagen , Denmark
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21
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Chung YR, Kim YH, Lee SY, Byeon HE, Lee K. Insights into the pathogenesis of cystoid macular edema: leukostasis and related cytokines. Int J Ophthalmol 2019; 12:1202-1208. [PMID: 31341814 DOI: 10.18240/ijo.2019.07.23] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 01/02/2019] [Indexed: 12/29/2022] Open
Abstract
Cystoid macular edema (CME) is the abnormal collection of intraretinal fluid in the macular region, especially in the inner nuclear and outer plexiform layers. CME leads to severe visual impairment in patients with various retinal diseases, such as diabetic retinopathy, retinal vascular occlusion, choroidal neovascularization, and uveitis. Although various retinal conditions lead to CME, a shared pathogenesis of CME is involved in these diseases. Accordingly, the pathogenesis of CME based on vasogenic mechanisms is first discussed in this review, including vascular hyperpermeability, leukostasis, and inflammation. We then describe cytotoxic mechanisms based on retinal Müller cell dysfunction. This comprehensive review will provide an understanding of the pathogenesis of CME for potential therapeutic strategies.
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Affiliation(s)
- Yoo-Ri Chung
- Department of Ophthalmology, Ajou University School of Medicine, Suwon 16499, Korea
| | - Young Ho Kim
- Department of Ophthalmology, Ajou University School of Medicine, Suwon 16499, Korea
| | - Seung Yeop Lee
- Department of Ophthalmology, Ajou University School of Medicine, Suwon 16499, Korea
| | - Hye-Eun Byeon
- Institute of Medical Science, Ajou University School of Medicine, Suwon 16499, Korea
| | - Kihwang Lee
- Department of Ophthalmology, Ajou University School of Medicine, Suwon 16499, Korea
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22
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Gardner MR, Rahman AS, Milner TE, Rylander HG. Scattering-Angle-Resolved Optical Coherence Tomography of a Hypoxic Mouse Retina Model. J Exp Neurosci 2019; 13:1179069519837564. [PMID: 30944521 PMCID: PMC6440039 DOI: 10.1177/1179069519837564] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 02/21/2019] [Indexed: 12/27/2022] Open
Abstract
Several studies have noted a correlation between retinal degeneration and traumatic encephalopathy (TE) making the retina a leading candidate for detection and assessment. Scattering-angle-resolved optical coherence tomography (SAR-OCT) is a candidate imaging modality to detect sub-resolution changes in retinal microstructure. SAR-OCT images of murine retinas that experience a hypoxic insult-euthanasia by isoflurane overdose-are presented. A total of 4 SAR-OCT measurement parameters are reported in 6 longitudinal experiments: blood flow volume fraction, total retinal thickness, reflectance index, and scattering angle. As each mouse expires, blood flow volume fraction decreases, total retinal thickness increases, reflectance index decreases, and scattering angle diversity increases. Contribution of the retinal vasculature to scattering angle diversity is discussed. Results of this study suggest the utility of SAR-OCT to measure TE using scattering angle diversity contrast in the retina.
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Affiliation(s)
- Michael R Gardner
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
- Department of Chemical Engineering, University of Bahrain, Isa Town, Bahrain
| | - Ayesha S Rahman
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Thomas E Milner
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
| | - Henry G Rylander
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, TX, USA
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23
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Rao SB, Katoozi S, Skauli N, Froehner SC, Ottersen OP, Adams ME, Amiry-Moghaddam M. Targeted deletion of β1-syntrophin causes a loss of K ir 4.1 from Müller cell endfeet in mouse retina. Glia 2019; 67:1138-1149. [PMID: 30803043 DOI: 10.1002/glia.23600] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 02/02/2023]
Abstract
Proper function of the retina depends heavily on a specialized form of retinal glia called Müller cells. These cells carry out important homeostatic functions that are contingent on their polarized nature. Specifically, the Müller cell endfeet that contact retinal microvessels and the corpus vitreum show a tenfold higher concentration of the inwardly rectifying potassium channel Kir 4.1 than other Müller cell plasma membrane domains. This highly selective enrichment of Kir 4.1 allows K+ to be siphoned through endfoot membranes in a special form of spatial buffering. Here, we show that Kir 4.1 is enriched in endfoot membranes through an interaction with β1-syntrophin. Targeted disruption of this syntrophin caused a loss of Kir 4.1 from Müller cell endfeet without affecting the total level of Kir 4.1 expression in the retina. Targeted disruption of α1-syntrophin had no effect on Kir 4.1 localization. Our findings show that the Kir 4.1 aggregation that forms the basis for K+ siphoning depends on a specific syntrophin isoform that colocalizes with Kir 4.1 in Müller endfoot membranes.
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Affiliation(s)
- Shreyas B Rao
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Shirin Katoozi
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Nadia Skauli
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Stanley C Froehner
- Department of Physiology and Biophysics, University of Washington, Seattle, Western Australia
| | - Ole Petter Ottersen
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Marvin E Adams
- Department of Physiology and Biophysics, University of Washington, Seattle, Western Australia
| | - Mahmood Amiry-Moghaddam
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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24
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Devoldere J, Peynshaert K, De Smedt SC, Remaut K. Müller cells as a target for retinal therapy. Drug Discov Today 2019; 24:1483-1498. [PMID: 30731239 DOI: 10.1016/j.drudis.2019.01.023] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 12/20/2018] [Accepted: 01/30/2019] [Indexed: 12/28/2022]
Abstract
Müller cells are specialized glial cells that span the entire retina from the vitreous cavity to the subretinal space. Their functional diversity and unique radial morphology render them particularly interesting targets for new therapeutic approaches. In this review, we reflect on various possibilities for selective Müller cell targeting and describe how some of their cellular mechanisms can be used for retinal neuroprotection. Intriguingly, cross-species investigation of their properties has revealed that Müller cells also have an essential role in retinal regeneration. Although many questions regarding this subject remain, it is clear that Müller cells have unique characteristics that make them suitable targets for the prevention and treatment of numerous retinal diseases.
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Affiliation(s)
- Joke Devoldere
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Karen Peynshaert
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Stefaan C De Smedt
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Katrien Remaut
- Ghent Research Group on Nanomedicines, Laboratory of General Biochemistry and Physical Pharmacy, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium; Cancer Research Institute Ghent (CRIG), Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium.
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25
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Bursting at the Seams: Molecular Mechanisms Mediating Astrocyte Swelling. Int J Mol Sci 2019; 20:ijms20020330. [PMID: 30650535 PMCID: PMC6359623 DOI: 10.3390/ijms20020330] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 01/10/2019] [Accepted: 01/11/2019] [Indexed: 01/31/2023] Open
Abstract
Brain swelling is one of the most robust predictors of outcome following brain injury, including ischemic, traumatic, hemorrhagic, metabolic or other injury. Depending on the specific type of insult, brain swelling can arise from the combined space-occupying effects of extravasated blood, extracellular edema fluid, cellular swelling, vascular engorgement and hydrocephalus. Of these, arguably the least well appreciated is cellular swelling. Here, we explore current knowledge regarding swelling of astrocytes, the most abundant cell type in the brain, and the one most likely to contribute to pathological brain swelling. We review the major molecular mechanisms identified to date that contribute to or mitigate astrocyte swelling via ion transport, and we touch upon the implications of astrocyte swelling in health and disease.
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26
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Neuronal degeneration and associated alterations in cytokine and protein in an experimental branch retinal venous occlusion model. Exp Eye Res 2018; 174:133-146. [DOI: 10.1016/j.exer.2018.05.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 05/18/2018] [Accepted: 05/23/2018] [Indexed: 11/22/2022]
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27
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Netti V, Pizzoni A, Pérez-Domínguez M, Ford P, Pasantes-Morales H, Ramos-Mandujano G, Capurro C. Release of taurine and glutamate contributes to cell volume regulation in human retinal Müller cells: differences in modulation by calcium. J Neurophysiol 2018; 120:973-984. [PMID: 29790838 DOI: 10.1152/jn.00725.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neuronal activity in the retina generates osmotic gradients that lead to Müller cell swelling, followed by a regulatory volume decrease (RVD) response, partially due to the isoosmotic efflux of KCl and water. However, our previous studies in a human Müller cell line (MIO-M1) demonstrated that an important fraction of RVD may also involve the efflux of organic solutes. We also showed that RVD depends on the swelling-induced Ca2+ release from intracellular stores. Here we investigate the contribution of taurine (Tau) and glutamate (Glu), the most relevant amino acids in Müller cells, to RVD through the volume-regulated anion channel (VRAC), as well as their Ca2+ dependency in MIO-M1 cells. Swelling-induced [3H]Tau/[3H]Glu release was assessed by radiotracer assays and cell volume by fluorescence videomicroscopy. Results showed that cells exhibited an osmosensitive efflux of [3H]Tau and [3H]Glu (Tau > Glu) blunted by VRAC inhibitors 4-(2-butyl-6,7-dichloro-2-cyclopentylindan-1-on-5-yl)-oxybutyric acid and carbenoxolone reducing RVD. Only [3H]Tau efflux was mainly dependent on Ca2+ release from intracellular stores. RVD was unaffected in a Ca2+-free medium, probably due to Ca2+-independent Tau and Glu release, but was reduced by chelating intracellular Ca2+. The inhibition of phosphatidylinositol-3-kinase reduced [3H]Glu efflux but also the Ca2+-insensitive [3H]Tau fraction and decreased RVD, providing evidence of the relevance of this Ca2+-independent pathway. We propose that VRAC-mediated Tau and Glu release has a relevant role in RVD in Müller cells. The observed disparities in Ca2+ influence on amino acid release suggest the presence of VRAC isoforms that may differ in substrate selectivity and regulatory mechanisms, with important implications for retinal physiology. NEW & NOTEWORTHY The mechanisms for cell volume regulation in retinal Müller cells are still unknown. We show that swelling-induced taurine and glutamate release mediated by the volume-regulated anion channel (VRAC) largely contributes the to the regulatory volume decrease response in a human Müller cell line. Interestingly, the hypotonic-induced efflux of these amino acids exhibits disparities in Ca2+-dependent and -independent regulatory mechanisms, which strongly suggests that Müller cells may express different VRAC heteromers formed by the recently discovered leucine-rich repeat containing 8 (LRRC8) proteins.
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Affiliation(s)
- Vanina Netti
- Universidad de Buenos Aires, Facultad de Medicina. Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas , Buenos Aires , Argentina.,CONICET-Universidad de Buenos Aires. Instituto de Fisiología y Biofísica "Bernardo Houssay," Buenos Aires, Argentina
| | - Alejandro Pizzoni
- Universidad de Buenos Aires, Facultad de Medicina. Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas , Buenos Aires , Argentina.,CONICET-Universidad de Buenos Aires. Instituto de Fisiología y Biofísica "Bernardo Houssay," Buenos Aires, Argentina
| | - Martha Pérez-Domínguez
- Departamento de Medicina Genómica y Toxicología Ambiental, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Paula Ford
- Universidad de Buenos Aires, Facultad de Medicina. Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas , Buenos Aires , Argentina.,CONICET-Universidad de Buenos Aires. Instituto de Fisiología y Biofísica "Bernardo Houssay," Buenos Aires, Argentina
| | - Herminia Pasantes-Morales
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Gerardo Ramos-Mandujano
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Claudia Capurro
- Universidad de Buenos Aires, Facultad de Medicina. Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas , Buenos Aires , Argentina.,CONICET-Universidad de Buenos Aires. Instituto de Fisiología y Biofísica "Bernardo Houssay," Buenos Aires, Argentina
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28
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Milton M, Smith PD. It's All about Timing: The Involvement of Kir4.1 Channel Regulation in Acute Ischemic Stroke Pathology. Front Cell Neurosci 2018; 12:36. [PMID: 29503609 PMCID: PMC5820340 DOI: 10.3389/fncel.2018.00036] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 01/30/2018] [Indexed: 01/28/2023] Open
Abstract
An acute ischemic stroke is characterized by the presence of a blood clot that limits blood flow to the brain resulting in subsequent neuronal loss. Acute stroke threatens neuronal survival, which relies heavily upon proper function of astrocytes. Neurons are more susceptible to cell death when an astrocyte is unable to carry out its normal functions in supporting the neuron in the area affected by the stroke (Rossi et al., 2007; Takano et al., 2009). For example, under normal conditions, astrocytes initially swell in response to changes in extracellular osmotic pressure and then reduce their regulatory volume in response to volume-activated potassium (K+) and chloride channels (Vella et al., 2015). This astroglial swelling may be overwhelmed, under ischemic conditions, due to the increased levels of glutamate and extracellular K+ (Lai et al., 2014; Vella et al., 2015). The increase in extracellular K+ contributes to neuronal damage and loss through the initiation of harmful secondary cascades (Nwaobi et al., 2016). Reducing the amount of extracellular K+ could, in theory, limit or prevent neuronal damage and loss resulting in an improved prognosis for individuals following ischemic stroke. Kir4.1, an inwardly rectifying K+ channel, has demonstrated an ability to regulate the rapid reuptake of this ion to return the cell to basal levels allowing it to fire again in rapid transmission (Sibille et al., 2015). Despite growing interest in this area, the underlying mechanism suggesting that neuroprotection could occur through modification of the Kir4.1 channel's activity has yet to be described. The purpose of this review is to examine the current literature and propose potential underlying mechanisms involving Kir4.1, specially the mammalian target of rapamycin (mTOR) and/or autophagic pathways, in the pathogenesis of ischemic stroke. The hope is that this review will instigate further investigation of Kir4.1 as a modulator of stroke pathology.
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Affiliation(s)
| | - Patrice D. Smith
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
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29
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Pannicke T, Wagner L, Reichenbach A, Grosche A. Electrophysiological characterization of Müller cells from the ischemic retina of mice deficient in the leukemia inhibitory factor. Neurosci Lett 2018; 670:69-74. [PMID: 29391217 DOI: 10.1016/j.neulet.2018.01.047] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 01/23/2018] [Accepted: 01/24/2018] [Indexed: 12/24/2022]
Abstract
Leukemia inhibitory factor (LIF) is a cytokine that exerts different effects in the nervous system. It is involved in neuronal injuries and diseases and is assumed to be neuroprotective and to regulate reactive gliosis. In LIF-deficient (LIF-/-) mice, expression of glial fibrillary acidic protein in retinal Müller glial cells as a hallmark of reactive gliosis is suppressed during retinal degenerations. Here, we detected expression of LIF and its receptors in Müller cells of the murine retina. Moreover, electrophysiological alterations of Müller cells 7 days after transient retinal ischemia were studied by the patch-clamp technique. The amplitude of inward currents in Müller cells from the postischemic retina was reduced to 51% in wild type and to 70% in LIF-/- mice. This demonstrates that decrease of inward currents takes place in reactive Müller cells even in the absence of LIF.
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Affiliation(s)
- Thomas Pannicke
- Paul-Flechsig-Institut für Hirnforschung, Universität Leipzig, Liebigstr. 19, D-04103 Leipzig, Germany.
| | - Lysann Wagner
- Paul-Flechsig-Institut für Hirnforschung, Universität Leipzig, Liebigstr. 19, D-04103 Leipzig, Germany
| | - Andreas Reichenbach
- Paul-Flechsig-Institut für Hirnforschung, Universität Leipzig, Liebigstr. 19, D-04103 Leipzig, Germany
| | - Antje Grosche
- Department of Physiological Genomics, Ludwig-Maximilians-Universität München, Großhaderner Str. 9, D-82152 Planegg-Martinsried, Germany
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30
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31
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Abstract
Müller glia, the principal macroglia of the retina, express diverse subtypes of adenosine and metabotropic purinergic (P2Y) receptors. Müller cells of several species, including man, also express ionotropic P2X7 receptors. ATP is liberated from Müller cells after activation of metabotropic glutamate receptors and during osmotic and mechanical induction of membrane stretch; adenosine is released through equilibrative nucleoside transporters. Müller cell-derived purines modulate the neuronal activity and have autocrine effects, for example, induction of glial calcium waves and regulation of the cellular volume. Glial calcium waves induced by neuron-derived ATP mediate functional hyperemia in the retina. Purinergic signaling contributes to the induction of Müller cell gliosis, for example, of cellular proliferation and downregulation of potassium channels, which are important for the homeostatic functions of Müller cells. Purinergic glial calcium waves may also promote the long-range propagation of gliosis and neuronal degeneration across the retinal tissue. The osmotic ATP release is inhibited under pathological conditions. Inhibition of the ATP release may result in osmotic Müller cell swelling and dysregulation of the water transport through the cells; both may contribute to the development of retinal edema. Suppression of the osmotic ATP release and upregulation of the ecto-apyrase (NTPDase1), which facilitate the extracellular degradation of ATP and the formation of adenosine, may protect neurons and photoreceptors from death due to overactivation of P2X receptors. Pharmacological inhibition of P2X7 receptors and stimulation of adenosine receptors may represent clinical approaches to prevent retinal cell death and dysregulated cell proliferation, and to treat retinal edema.
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Affiliation(s)
- Andreas Reichenbach
- 1 Paul Flechsig Institute of Brain Research, University of Leipzig , Leipzig, Germany
| | - Andreas Bringmann
- 2 Department of Ophthalmology and Eye Hospital, University of Leipzig , Leipzig, Germany
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32
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Mechanisms of macular edema: Beyond the surface. Prog Retin Eye Res 2017; 63:20-68. [PMID: 29126927 DOI: 10.1016/j.preteyeres.2017.10.006] [Citation(s) in RCA: 365] [Impact Index Per Article: 52.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 10/24/2017] [Accepted: 10/31/2017] [Indexed: 02/07/2023]
Abstract
Macular edema consists of intra- or subretinal fluid accumulation in the macular region. It occurs during the course of numerous retinal disorders and can cause severe impairment of central vision. Major causes of macular edema include diabetes, branch and central retinal vein occlusion, choroidal neovascularization, posterior uveitis, postoperative inflammation and central serous chorioretinopathy. The healthy retina is maintained in a relatively dehydrated, transparent state compatible with optimal light transmission by multiple active and passive systems. Fluid accumulation results from an imbalance between processes governing fluid entry and exit, and is driven by Starling equation when inner or outer blood-retinal barriers are disrupted. The multiple and intricate mechanisms involved in retinal hydro-ionic homeostasis, their molecular and cellular basis, and how their deregulation lead to retinal edema, are addressed in this review. Analyzing the distribution of junction proteins and water channels in the human macula, several hypotheses are raised to explain why edema forms specifically in the macular region. "Pure" clinical phenotypes of macular edema, that result presumably from a single causative mechanism, are detailed. Finally, diabetic macular edema is investigated, as a complex multifactorial pathogenic example. This comprehensive review on the current understanding of macular edema and its mechanisms opens perspectives to identify new preventive and therapeutic strategies for this sight-threatening condition.
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33
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Coughlin BA, Feenstra DJ, Mohr S. Müller cells and diabetic retinopathy. Vision Res 2017; 139:93-100. [PMID: 28866025 PMCID: PMC5794018 DOI: 10.1016/j.visres.2017.03.013] [Citation(s) in RCA: 203] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Revised: 03/27/2017] [Accepted: 03/30/2017] [Indexed: 12/17/2022]
Abstract
Müller cells are one of the primary glial cell types found in the retina and play a significant role in maintaining retinal function and health. Since Müller cells are the only cell type to span the entire width of the retina and have contact to almost every cell type in the retina they are uniquely positioned to perform a wide variety of functions necessary to maintaining retinal homeostasis. In the healthy retina, Müller cells recycle neurotransmitters, prevent glutamate toxicity, redistribute ions by spatial buffering, participate in the retinoid cycle, and regulate nutrient supplies by multiple mechanisms. Any disturbance to the retinal environment is going to influence proper Müller cell function and well being which in turn will affect the entire retina. This is evident in a disease like diabetic retinopathy where Müller cells contribute to neuronal dysfunction, the production of pro-angiogenic factors leading to neovascularization, the set up of a chronic inflammatory retinal environment, and eventual cell death. In this review, we highlight the importance of Müller cells in maintaining a healthy and functioning retina and discuss various pathological events of diabetic retinopathy in which Müller cells seem to play a crucial role. The beneficial and detrimental effects of cytokine and growth factor production by Müller cells on the microvasculature and retinal neuronal tissue will be outlined. Understanding Müller cell functions within the retina and restoring such function in diabetic retinopathy should become a cornerstone for developing effective therapies to treat diabetic retinopathy.
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Affiliation(s)
- Brandon A Coughlin
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Derrick J Feenstra
- Department of Physiology, Michigan State University, East Lansing, MI, USA
| | - Susanne Mohr
- Department of Physiology, Michigan State University, East Lansing, MI, USA.
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34
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Setkowicz Z, Kosonowska E, Janeczko K. Inflammation in the developing rat modulates astroglial reactivity to seizures in the mature brain. J Anat 2017; 231:366-379. [PMID: 28597918 DOI: 10.1111/joa.12636] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2017] [Indexed: 11/29/2022] Open
Abstract
Astrocytes participate in neuronal development and excitability, and produce factors enhancing or suppressing inflammatory processes occurring due to neurodegenerative diseases, such as epilepsy. Seizures, in turn, trigger the release of inflammatory mediators, causing structural and functional changes in the brain. Therefore, it appears reasonable to determine whether generalized inflammation at developmental periods can affect astrocyte reactivity to epileptic seizures occurring in the adult brain. Lipopolysaccharide (LPS) was injected in 6- or 30-day-old rats (P6 or P30, respectively). At the age of 2 months, seizures were induced, and pilocarpine and morphological changes of astrocytes located within the hippocampal formation were assessed. Additionally, expression of glial fibrillary acidic protein (GFAP), glutamine synthetase (GS), aquaporin 4 (AQP4), and inwardly rectifying potassium channel Kir 4.1 (Kir4.1) was determined using Western blots. The animal group given LPS on P6 displayed maximal susceptibility to pilocarpine-induced seizures, significantly higher than the group that received LPS on P30. In the immunohistologically examined hippocampal formation, the GFAP-immunoreactive area was not affected by LPS alone. However, it was reduced following seizures in naïve controls but not in LPS-pretreated rats. Increases in the ramification of astrocytic processes were detected only in adult rats given LPS on P30, not on P6. Seizures abolished the effects. Following seizures, the process ramification showed no significant change in the two LPS-treated rat groups, whereas it was significantly reduced in the dentate gyrus of LPS-untreated controls. Glial fibrillary acidic protein (GFAP) expression showed no changes induced with LPS alone and rose slightly after seizures. AQP4 content was lower in rats given LPS on P6 and was seizure-resistant in the two LPS-treated groups, contrary to a decrease in untreated controls. GS expression was not affected by LPS treatments and was reduced after seizures without an intergroup difference. Kir4.1 underwent highly significant increases in all groups experiencing seizures, but LPS alone had no effect. It can be concluded that the generalized inflammatory status led to some important changes in astrocytes reflected, in part at least by permanent modifications of their morphology and molecular profile. Moreover, the previously experienced inflammation prevented the cells from much stronger changes in response to seizures observed in adult untreated controls. The obtained results point to a link between the activation of astrocytes by transient systemic inflammation occurring during the developmental period and their subsequent reactivity to seizures, which may play an important role in the functional features of the brain, including its susceptibility to seizures.
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Affiliation(s)
- Zuzanna Setkowicz
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Krakow, Poland
| | - Emilia Kosonowska
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Krakow, Poland
| | - Krzysztof Janeczko
- Department of Neuroanatomy, Institute of Zoology, Jagiellonian University, Krakow, Poland
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35
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Netti V, Fernández J, Kalstein M, Pizzoni A, Di Giusto G, Rivarola V, Ford P, Capurro C. TRPV4 Contributes to Resting Membrane Potential in Retinal Müller Cells: Implications in Cell Volume Regulation. J Cell Biochem 2017; 118:2302-2313. [PMID: 28098409 DOI: 10.1002/jcb.25884] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/13/2017] [Indexed: 11/10/2022]
Abstract
Neural activity alters osmotic gradients favoring cell swelling in retinal Müller cells. This swelling is followed by a regulatory volume decrease (RVD), partially mediated by an efflux of KCl and water. The transient receptor potential channel 4 (TRPV4), a nonselective calcium channel, has been proposed as a candidate for mediating intracellular Ca2+ elevation induced by swelling. We previously demonstrated in a human Müller cell line (MIO-M1) that RVD strongly depends on ion channel activation and, consequently, on membrane potential (Vm ). The aim of this study was to investigate if Ca2+ influx via TRPV4 contributes to RVD by modifying intracellular Ca2+ concentration and/or modulating Vm in MIO-M1 cells. Cell volume, intracellular Ca2+ levels, and Vm changes were evaluated using fluorescent probes. Results showed that MIO-M1 cells express functional TRPV4 which determines the resting Vm associated with K+ channels. Swelling-induced increases in Ca2+ levels was due to both Ca2+ release from intracellular stores and Ca2+ influx by a pathway alternative to TRPV4. TRPV4 blockage affected swelling-induced biphasic response (depolarization-repolarization), suggesting its participation in modulating Vm changes during RVD. Agonist stimulation of Ca2+ influx via TRPV4 activated K+ channels hyperpolarizing Vm and accelerating RVD. We propose that TRPV4 forms a signaling complex with Ca2+ and/or voltage-dependent K+ channels to define resting Vm and Vm changes during RVD. TRPV4 involvement in RVD depends on the type of stimuli and/or degree of channel activation, leading to a maximum RVD response when Ca2+ influx overcomes a threshold and activates further signaling pathways in cell volume regulation. J. Cell. Biochem. 118: 2302-2313, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Vanina Netti
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Juan Fernández
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Maia Kalstein
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Alejandro Pizzoni
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gisela Di Giusto
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Valeria Rivarola
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Paula Ford
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Claudia Capurro
- Laboratorio de Biomembranas, IFIBIO Houssay, CONICET-UBA, Departamento de Ciencia Fisiológicas, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
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36
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Abstract
: Retinal vascular disease has the potential to affect hundreds of millions of people, with the inherent risk of vision loss related to cystoid macular edema. Although there have been histologic evaluation of eyes having cystoid macular edema, the most recent paper was published more than 30 years ago. In retinal vascular cystoid macular edema fluorescein angiography, a modality that images the superficial vascular plexus, shows increased leakage. Optical coherence tomography angiography has provided unprecedented resolution of retinal vascular flow in a depth resolved manner and demonstrates areas of decreased or absent flow in the deep vascular plexus colocalizing with the cystoid spaces. There has been a large amount of research on fluid management and edema in the brain, much of which may have analogues in the eye. Interstitial flow of fluid as managed by Müller cells may occur in the retina, comparable in some ways to the bulk flow in brain parenchyma, which is managed by astrocytes. Absent blood flow in the deep retinal plexus may restrict fluid management strategies in the retina, to include transport of excess fluid out of the retina into the blood by Müller cells. Application of this theory may help in increasing understanding of the pathophysiology of retinal vascular cystoid macular edema and may lead to new therapeutic approaches.
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Yin H, Wang H, Zhang H, Gao N, Zhang T, Yang Z. Resveratrol Attenuates Aβ-Induced Early Hippocampal Neuron Excitability Impairment via Recovery of Function of Potassium Channels. Neurotox Res 2017; 32:311-324. [PMID: 28361268 DOI: 10.1007/s12640-017-9726-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 03/08/2017] [Accepted: 03/13/2017] [Indexed: 12/20/2022]
Abstract
Alzheimer's disease (AD) is an age-related neurodegenerative disease. Amyloid-β (Aβ) is not only the morphological hallmark but also the initiator of the pathology process of AD. As a natural compound found in grapes, resveratrol shows a protective effect on the pathophysiology of AD, but the underlying mechanism is not very clear. This study was to investigate whether resveratrol could attenuate Aβ-induced early impairment in hippocampal neuron excitability and the underlying mechanism. The excitability and voltage-gated potassium currents were examined in rat hippocampal CA1 pyramidal neurons by using whole-cell patch-clamp technique. It was found that Aβ25-35 increased the excitability of neurons. Resveratrol could reverse the Aβ25-35-induced increase in the frequency of repetitive firing and the spike half-width of action potential (AP). Moreover, resveratrol can attenuate Aβ25-35-induced decreases in transient potassium channel (I A ) and delay rectifier potassium channel (I K(DR)) of neurons. It was also found that resveratrol could decline the increase of protein kinase A (PKA) and inhibit the activation of PI3K/Akt signaling pathway induced by Aβ25-35. The results suggest that resveratrol alleviates Aβ25-35-induced dysfunction in hippocampal CA1 pyramidal neurons via recovery of the function of I A and I K(DR) by inhibiting the increase of PKA and the activation of PI3K/Akt signaling pathway.
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Affiliation(s)
- Hongqiang Yin
- School of Medicine, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, 300071, People's Republic of China
| | - Hui Wang
- College of Life Sciences and Key Laboratory of Bioactive Materials Ministry of Education, Nankai University, Tianjin, 300071, People's Republic of China
| | - Hui Zhang
- College of Life Sciences and Key Laboratory of Bioactive Materials Ministry of Education, Nankai University, Tianjin, 300071, People's Republic of China
| | - Na Gao
- School of Medicine, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, 300071, People's Republic of China.,Tianjin Medical University Cancer Institute and Hospital, Tianjin, 300200, People's Republic of China
| | - Tao Zhang
- College of Life Sciences and Key Laboratory of Bioactive Materials Ministry of Education, Nankai University, Tianjin, 300071, People's Republic of China
| | - Zhuo Yang
- School of Medicine, State Key Laboratory of Medicinal Chemical Biology, Nankai University, Tianjin, 300071, People's Republic of China.
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Fuma S, Nishinaka A, Inoue Y, Tsuruma K, Shimazawa M, Kondo M, Hara H. A pharmacological approach in newly established retinal vein occlusion model. Sci Rep 2017; 7:43509. [PMID: 28252108 PMCID: PMC5333144 DOI: 10.1038/srep43509] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 01/25/2017] [Indexed: 11/09/2022] Open
Abstract
The mechanism underlying the effects of anti-vascular endothelial growth factor (VEGF) antibody in retinal vein occlusion (RVO) treatment is poorly understood, partly due to the lack of RVO animal models that mimic clinical pathology. The aims of this study were to establish a suitable RVO model, clarify the pathogenic mechanisms, and evaluate the effects of anti-VEGF antibody in the model. Mouse retinal veins were occluded by laser photocoagulation after rose bengal injection. Reduction of the b/a wave amplitude ratio, retinal nonperfusion, cystoid edema, and hard exudates were observed after occlusion, and expression of RVO-related genes was altered. Administration of anti-VEGF antibody immediately, or 7 days, after occlusion resulted in reduction and increase of the nonperfused area, respectively. We conclude that the present model will be useful for clarification of the pathogenic mechanisms, and that the timing of anti-VEGF antibody administration is important for the successful amelioration of retinal nonperfusion.
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Affiliation(s)
- Shinichiro Fuma
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan
| | - Anri Nishinaka
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan
| | - Yuki Inoue
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan
| | - Kazuhiro Tsuruma
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan
| | - Masamitsu Shimazawa
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan
| | - Mineo Kondo
- Department of Ophthalmology, Mie University Graduate School of Medicine, Tsu, Japan
| | - Hideaki Hara
- Molecular Pharmacology, Department of Biofunctional Evaluation, Gifu Pharmaceutical University, Gifu, Japan
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Nwaobi SE, Cuddapah VA, Patterson KC, Randolph AC, Olsen ML. The role of glial-specific Kir4.1 in normal and pathological states of the CNS. Acta Neuropathol 2016; 132:1-21. [PMID: 26961251 PMCID: PMC6774634 DOI: 10.1007/s00401-016-1553-1] [Citation(s) in RCA: 150] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 02/16/2016] [Accepted: 02/25/2016] [Indexed: 12/15/2022]
Abstract
Kir4.1 is an inwardly rectifying K(+) channel expressed exclusively in glial cells in the central nervous system. In glia, Kir4.1 is implicated in several functions including extracellular K(+) homeostasis, maintenance of astrocyte resting membrane potential, cell volume regulation, and facilitation of glutamate uptake. Knockout of Kir4.1 in rodent models leads to severe neurological deficits, including ataxia, seizures, sensorineural deafness, and early postnatal death. Accumulating evidence indicates that Kir4.1 plays an integral role in the central nervous system, prompting many laboratories to study the potential role that Kir4.1 plays in human disease. In this article, we review the growing evidence implicating Kir4.1 in a wide array of neurological disease. Recent literature suggests Kir4.1 dysfunction facilitates neuronal hyperexcitability and may contribute to epilepsy. Genetic screens demonstrate that mutations of KCNJ10, the gene encoding Kir4.1, causes SeSAME/EAST syndrome, which is characterized by early onset seizures, compromised verbal and motor skills, profound cognitive deficits, and salt-wasting. KCNJ10 has also been linked to developmental disorders including autism. Cerebral trauma, ischemia, and inflammation are all associated with decreased astrocytic Kir4.1 current amplitude and astrocytic dysfunction. Additionally, neurodegenerative diseases such as Alzheimer disease and amyotrophic lateral sclerosis demonstrate loss of Kir4.1. This is particularly exciting in the context of Huntington disease, another neurodegenerative disorder in which restoration of Kir4.1 ameliorated motor deficits, decreased medium spiny neuron hyperexcitability, and extended survival in mouse models. Understanding the expression and regulation of Kir4.1 will be critical in determining if this channel can be exploited for therapeutic benefit.
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Affiliation(s)
- Sinifunanya E Nwaobi
- Department of Cell, Developmental and Integrative Biology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, AL, 35294, UK
| | - Vishnu A Cuddapah
- Department of Cell, Developmental and Integrative Biology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, AL, 35294, UK
| | - Kelsey C Patterson
- Department of Cell, Developmental and Integrative Biology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, AL, 35294, UK
| | - Anita C Randolph
- Department of Cell, Developmental and Integrative Biology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, AL, 35294, UK
| | - Michelle L Olsen
- Department of Cell, Developmental and Integrative Biology, Center for Glial Biology in Medicine, University of Alabama at Birmingham, 1918 University Blvd, Birmingham, AL, 35294, UK.
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Lassiale S, Valamanesh F, Klein C, Hicks D, Abitbol M, Versaux-Botteri C. Changes in aquaporin-4 and Kir4.1 expression in rats with inherited retinal dystrophy. Exp Eye Res 2016; 148:33-44. [DOI: 10.1016/j.exer.2016.05.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Revised: 05/04/2016] [Accepted: 05/09/2016] [Indexed: 10/21/2022]
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Endothelins Inhibit Osmotic Swelling of Rat Retinal Glial and Bipolar Cells by Activation of Growth Factor Signaling. Neurochem Res 2016; 41:2598-2606. [PMID: 27278757 DOI: 10.1007/s11064-016-1971-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 05/27/2016] [Accepted: 05/30/2016] [Indexed: 12/23/2022]
Abstract
Water accumulation in retinal glial (Müller) and neuronal cells resulting in cellular swelling contributes to the development of retinal edema and neurodegeneration. Here, we show that endothelin-1 (ET-1) dose-dependently inhibits the hypoosmotic swelling of Müller cells in freshly isolated retinal slices of control and diabetic rats, with a maximal inhibition at 100 nM. Osmotic Müller cell swelling was also inhibited by ET-2. The effect of ET-1 was mediated by activation of ETA and ETB receptors resulting in transactivation of metabotropic glutamate receptors, purinergic P2Y1, and adenosine A1 receptors. ET-1 (but not ET-2) also inhibited the osmotic swelling of bipolar cells in retinal slices, but failed to inhibit the swelling of freshly isolated bipolar cells. The inhibitory effect of ET-1 on the bipolar cell swelling in retinal slices was abrogated by inhibitors of the FGF receptor kinase (PD173074) and of TGF-β1 superfamily activin receptor-like kinase receptors (SB431542), respectively. Both Müller and bipolar cells displayed immunoreactivities of ETA and ETB receptor proteins. The data may suggest that neuroprotective effects of ETs in the retina are in part mediated by prevention of the cytotoxic swelling of retinal glial and bipolar cells. ET-1 acts directly on Müller cells, while the inhibitory effect of ET-1 on bipolar cell swelling is indirectly mediated, via stimulation of the release of growth factors like bFGF and TGF-β1 from Müller cells.
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Joly S, Dodd DA, Grewe BF, Pernet V. Reticulon 4A/Nogo-A influences the distribution of Kir4.1 but is not essential for potassium conductance in retinal Müller glia. Neurosci Lett 2016; 627:168-77. [PMID: 27276652 DOI: 10.1016/j.neulet.2016.06.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 06/02/2016] [Accepted: 06/04/2016] [Indexed: 11/29/2022]
Abstract
In the adult retina, we have previously shown that Nogo-A was highly expressed in Müller glia. However, the role of Nogo-A in the glial cell physiology is not clear. In this study, we investigated the possible influence that Nogo-A may exert on other polarized molecules in Müller cells, in particular inwardly rectifying potassium channel 4.1 (Kir4.1) and aquaporin 4 (AQP4) that respectively control potassium and water exchange in glial cells. Our results showed that adenovirus-mediated Nogo-A overexpression with AdNogo-A increased the immunofluorescent signal of Kir4.1 in rat Müller cell line 1 (rMC-1) cells but did not change its expression level by Western blotting. In vivo, AdNogo-A induced ectopic Kir4.1 immunoreactivity throughout the radial processes of Müller cells compared with AdLacZ control virus. Surprisingly, AdNogo-A did not modify the distribution of Dp71 and AQP4 that are common binding partners for Kir4.1 in the dystrophin-associated protein (DAP) complex anchored at the plasma membrane of Müller glia. Immunoprecipitation experiments revealed molecular interactions between Nogo-A and Kir4.1. In Nogo-A KO mouse retinae, the distribution of Kir4.1 was not different from that observed in Wild-Type (WT) animals. In addition, potassium conductance did not change in freshly dissociated Nogo-A KO Müller glia compared with WT cells. In summary, the increase of Nogo-A expression can selectively influence the distribution of Kir4.1 in glia but is not essential for Kir4.1-mediated potassium conductance at the plasma membrane in physiological conditions. Nogo-A-Kir4.1 interactions may, however, contribute to pathological processes taking place in the retina, for instance, after ischemia.
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Affiliation(s)
- Sandrine Joly
- CUO-Recherche, Médecine Régénératrice-Centre de recherche FRQS du CHU de Québec-Université Laval, Université Laval, Québec, Canada; Centre de Recherche en Organogénèse expérimentale de l'Université Laval/LOEX, Québec, QC, Canada; Département d'Ophtalmologie, Faculté de médecine, Université Laval, Québec, QC, Canada
| | - Dana A Dodd
- University of Texas Southwestern Medical Center, Department of Microbiology, Dallas, TX, USA
| | | | - Vincent Pernet
- CUO-Recherche, Médecine Régénératrice-Centre de recherche FRQS du CHU de Québec-Université Laval, Université Laval, Québec, Canada; Centre de Recherche en Organogénèse expérimentale de l'Université Laval/LOEX, Québec, QC, Canada; Département d'Ophtalmologie, Faculté de médecine, Université Laval, Québec, QC, Canada.
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Retinal Macroglial Responses in Health and Disease. BIOMED RESEARCH INTERNATIONAL 2016; 2016:2954721. [PMID: 27294114 PMCID: PMC4887628 DOI: 10.1155/2016/2954721] [Citation(s) in RCA: 109] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 04/14/2016] [Indexed: 12/20/2022]
Abstract
Due to their permanent and close proximity to neurons, glial cells perform essential tasks for the normal physiology of the retina. Astrocytes and Müller cells (retinal macroglia) provide physical support to neurons and supplement them with several metabolites and growth factors. Macroglia are involved in maintaining the homeostasis of extracellular ions and neurotransmitters, are essential for information processing in neural circuits, participate in retinal glucose metabolism and in removing metabolic waste products, regulate local blood flow, induce the blood-retinal barrier (BRB), play fundamental roles in local immune response, and protect neurons from oxidative damage. In response to polyetiological insults, glia cells react with a process called reactive gliosis, seeking to maintain retinal homeostasis. When malfunctioning, macroglial cells can become primary pathogenic elements. A reactive gliosis has been described in different retinal pathologies, including age-related macular degeneration (AMD), diabetes, glaucoma, retinal detachment, or retinitis pigmentosa. A better understanding of the dual, neuroprotective, or cytotoxic effect of macroglial involvement in retinal pathologies would help in treating the physiopathology of these diseases. The extensive participation of the macroglia in retinal diseases points to these cells as innovative targets for new drug therapies.
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Vogler S, Pannicke T, Hollborn M, Kolibabka M, Wiedemann P, Reichenbach A, Hammes HP, Bringmann A. Impaired Purinergic Regulation of the Glial (Müller) Cell Volume in the Retina of Transgenic Rats Expressing Defective Polycystin-2. Neurochem Res 2016; 41:1784-96. [PMID: 27038933 DOI: 10.1007/s11064-016-1894-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 03/16/2016] [Accepted: 03/17/2016] [Indexed: 12/19/2022]
Abstract
Retinal glial (Müller) cells possess an endogenous purinergic signal transduction cascade which normally prevents cellular swelling in osmotic stress. The cascade can be activated by osmotic or glutamate receptor-dependent ATP release. We determined whether activation of this cascade is altered in Müller cells of transgenic rats that suffer from a slow photoreceptor degeneration due to the expression of a truncated human cilia gene polycystin-2 (CMV-PKD21/703 HA). Age-matched Sprague-Dawley rats served as control. Retinal slices were superfused with a hypoosmotic solution (60 % osmolarity). Müller cells in retinas of PKD21/703 rats swelled immediately in hypoosmotic stress; this was not observed in control retinas. Pharmacological blockade of P2Y1 or adenosine A1 receptors induced osmotic swelling of Müller cells from control rats. The swelling induced by the P2Y1 receptor antagonist was mediated by induction of oxidative-nitrosative stress, mitochondrial dysfunction, production of inflammatory lipid mediators, and a sodium influx from the extracellular space. Exogenous VEGF or glutamate prevented the hypoosmotic swelling of Müller cells from PKD21/703 rats; this effect was mediated by activation of the purinergic signaling cascade. In neuroretinas of PKD21/703 rats, the gene expression levels of P2Y1 and A1 receptors, pannexin-1, connexin 45, NTPDases 1 and 2, and various subtypes of nucleoside transporters are elevated compared to control. The data may suggest that the osmotic swelling of Müller cells from PKD21/703 rats is caused by an abrogation of the osmotic ATP release while the glutamate-induced ATP release is functional. In the normal retina, ATP release and autocrine P2Y1 receptor activation serve to inhibit the induction of oxidative-nitrosative stress, mitochondrial dysfunction, and production of inflammatory lipid mediators, which otherwise will induce a sodium influx and cytotoxic Müller cell swelling under anisoosmotic conditions. Purinergic receptors may represent a target for the protection of retinal glial cells from mitochondrial oxidative stress.
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Affiliation(s)
- Stefanie Vogler
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Thomas Pannicke
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Margrit Hollborn
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Liebigstrasse 10-14, 04103, Leipzig, Germany
| | - Matthias Kolibabka
- 5th Medical Department, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Liebigstrasse 10-14, 04103, Leipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany
| | - Hans-Peter Hammes
- 5th Medical Department, Medical Faculty Mannheim, University of Heidelberg, Mannheim, Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Liebigstrasse 10-14, 04103, Leipzig, Germany.
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Vogler S, Hollborn M, Berk BA, Pannicke T, Seeger J, Wiedemann P, Reichenbach A, Bringmann A. Ischemic regulation of brain-derived neurotrophic factor-mediated cell volume and TrkB expression in glial (Müller) and bipolar cells of the rat retina. Graefes Arch Clin Exp Ophthalmol 2016; 254:497-503. [PMID: 26743749 DOI: 10.1007/s00417-015-3250-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Revised: 12/13/2015] [Accepted: 12/21/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Osmotic swelling of neurons and glial cells contributes to retinal edema and neurodegeneration. BDNF, a major neuroprotectant in the retina, was shown to inhibit osmotic swelling of glial (Müller) and bipolar cells in the rat retina; the effect of BDNF on the bipolar cell swelling is mediated by inducing a release of neuroprotective cytokines from Müller cells (Berk et al., Neuroscience 295:175-186, 2015). We determined whether BDNF-mediated cell volume regulation was altered after transient retinal ischemia. METHODS Retinal slices from the eyes of rats that underwent a 1-h pressure-induced retinal ischemia and from control eyes were superfused with a hypoosmotic solution. RESULTS Exogenous BDNF prevented osmotic swelling of Müller cells in both control and post-ischemic retinal slices. BDNF also prevented osmotic swelling of bipolar cells in the control retina, but not in the ischemic retina. On the other hand, exogenous bFGF prevented the swelling of both Müller and bipolar cells in the ischemic retina. Freshly isolated Müller cells of control retinas displayed immunoreactivity of truncated but not full-length TrkB. In contrast, Müller cells of post-ischemic retinas displayed immunoreactivity of both TrkB isoforms. Bipolar cells isolated from control and post-ischemic retinas were immunolabeled for both TrkB isoforms. CONCLUSIONS The data may suggest that the ischemic abrogation of the BDNF effect in bipolar cells is related to altered BDNF receptor expression in Müller cells. Glial upregulation of full-length TrkB may support the survival of Müller cells in the ischemic retina, but may impair the BDNF-induced release of neuroprotective cytokines such as bFGF from Müller cells.
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Affiliation(s)
- Stefanie Vogler
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Margrit Hollborn
- Department of Ophthalmology and Eye Hospital, Medical Faculty, University of Leipzig, Liebigstrasse 10-14, D-04103, Leipzig, Germany
| | - Benjamin-Andreas Berk
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, Leipzig, Germany.,Institute of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - Thomas Pannicke
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Johannes Seeger
- Institute of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Leipzig, Leipzig, Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital, Medical Faculty, University of Leipzig, Liebigstrasse 10-14, D-04103, Leipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, Medical Faculty, University of Leipzig, Leipzig, Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, Medical Faculty, University of Leipzig, Liebigstrasse 10-14, D-04103, Leipzig, Germany.
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Najafi E, Stoodley MA, Bilston LE, Hemley SJ. Inwardly rectifying potassium channel 4.1 expression in post-traumatic syringomyelia. Neuroscience 2016; 317:23-35. [PMID: 26768400 DOI: 10.1016/j.neuroscience.2016.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Revised: 12/23/2015] [Accepted: 01/02/2016] [Indexed: 10/22/2022]
Abstract
Post-traumatic syringomyelia (PTS) is a serious neurological disorder characterized by fluid filled cavities that develop in the spinal cord. PTS is thought to be caused by an imbalance between fluid inflow and outflow in the spinal cord, but the underlying mechanisms are unknown. The ion channel Kir4.1 plays an important role in the uptake of K(+) ions from the extracellular space and release of K(+) ions into the microvasculature, generating an osmotic gradient that drives water movement. Changes in Kir4.1 expression may contribute to disturbances in K(+) homeostasis and subsequently fluid imbalance. Here we investigated whether changes in Kir4.1 protein expression occur in PTS. Western blotting and immunohistochemistry were used to evaluate Kir4.1 and glial fibrillary acidic protein (GFAP) expression in a rodent model of PTS at 3 days, 1, 6 or 12 weeks post-surgery. In Western blotting experiments, Kir4.1 expression increased 1 week post-surgery at the level of the cavity. Immunohistochemical analysis examined changes in the spinal parenchyma directly in contact with the syrinx cavity. In these experiments, there was a significant decrease in Kir4.1 expression in PTS animals compared to controls at 3 days and 6 weeks post-surgery, while an up-regulation of GFAP in PTS animals was observed at 1 and 12 weeks. This suggests that while overall Kir4.1 expression is unchanged at these time-points, there are many astrocytes surrounding the syrinx cavity that are not expressing Kir4.1. The results demonstrate a disturbance in the removal of K(+) ions in tissue surrounding a post-traumatic syrinx cavity. It is possible this contributes to water accumulation in the injured spinal cord leading to syrinx formation or exacerbation of the underlying pathology.
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Affiliation(s)
- E Najafi
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia.
| | - M A Stoodley
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia.
| | - L E Bilston
- Neuroscience Research Australia, Sydney, NSW, Australia; Prince of Wales Clinical School, University of New South Wales, Randwick, NSW, Australia.
| | - S J Hemley
- Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia.
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Minkel HR, Anwer TZ, Arps KM, Brenner M, Olsen ML. Elevated GFAP induces astrocyte dysfunction in caudal brain regions: A potential mechanism for hindbrain involved symptoms in type II Alexander disease. Glia 2015; 63:2285-97. [PMID: 26190408 PMCID: PMC4555878 DOI: 10.1002/glia.22893] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 07/01/2015] [Indexed: 12/14/2022]
Abstract
Alexander Disease (AxD) is a "gliopathy" caused by toxic, dominant gain-of-function mutations in the glial fibrillary acidic protein (GFAP) gene. Two distinct types of AxD exist. Type I AxD affected individuals develop cerebral symptoms by 4 years of age and suffer from macrocephaly, seizures, and physical and mental delays. As detection and diagnosis have improved, approximately half of all AxD patients diagnosed have onset >4 years and brainstem/spinal cord involvement. Type II AxD patients experience ataxia, palatal myoclonus, dysphagia, and dysphonia. No study has examined a mechanistic link between the GFAP mutations and caudal symptoms present in type II AxD patients. We demonstrate that two key astrocytic functions, the ability to regulate extracellular glutamate and to take up K(+) via K+ channels, are compromised in hindbrain regions and spinal cord in AxD mice. Spinal cord astrocytes in AxD transgenic mice are depolarized relative to WT littermates, and have a three-fold reduction in Ba(2+) -sensitive Kir4.1 mediated currents and six-fold reduction in glutamate uptake currents. The loss of these two functions is due to significant decreases in Kir4.1 (>70%) and GLT-1 (>60%) protein expression. mRNA expression for KCNJ10 and SLC1A2, the genes that code for Kir4.1 and GLT-1, are significantly reduced by postnatal Day 7. Protein and mRNA reductions for Kir4.1 and GLT-1 are exacerbated in AxD models that demonstrate earlier accumulation of GFAP and increased Rosenthal fiber formation. These findings provide a mechanistic link between the GFAP mutations/overexpression and the symptoms in those affected with Type II AxD.
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Affiliation(s)
- Heather R Minkel
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Tooba Z Anwer
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Kara M Arps
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama
| | - Michael Brenner
- Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama
- Department of Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama
| | - Michelle L Olsen
- Department of Cell, Developmental and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama
- Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, Alabama
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48
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Vogler S, Winters H, Pannicke T, Wiedemann P, Reichenbach A, Bringmann A. Sigma-1 receptor activation inhibits osmotic swelling of rat retinal glial (Müller) cells by transactivation of glutamatergic and purinergic receptors. Neurosci Lett 2015; 610:13-8. [PMID: 26499958 DOI: 10.1016/j.neulet.2015.10.042] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/05/2015] [Accepted: 10/14/2015] [Indexed: 12/28/2022]
Abstract
Water accumulation in retinal glial (Müller) and neuronal cells resulting in cellular swelling contributes to the development of retinal edema and neurodegeneration. Sigma (σ) receptor activation is known to have neuroprotective effects in the retina. Here, we show that the nonselective σ receptor agonist ditolylguanidine, and the selective σ1 receptor agonist PRE-084, inhibit the osmotic swelling of Müller cell somata induced by superfusion of rat retinal slices with a hypoosmotic solution containing barium ions. In contrast, PRE-084 did not inhibit the osmotic swelling of bipolar cell somata. The effects of σ receptor agonists on the Müller cell swelling were abrogated in the presence of blockers of metabotropic glutamate and purinergic P2Y1 receptors, respectively, suggesting that σ receptor activation triggers activation of a glutamatergic-purinergic signaling cascade which is known to prevent the osmotic Müller cell swelling. The swelling-inhibitory effect of 17β-estradiol was prevented by the σ1 receptor antagonist BD1047, suggesting that the effect is mediated by σ1 receptor activation. The data may suggest that the neuroprotective effect of σ receptor activation in the retina is in part mediated by prevention of the cytotoxic swelling of retinal glial cells.
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Affiliation(s)
- Stefanie Vogler
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Helge Winters
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Thomas Pannicke
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Peter Wiedemann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, 04103 Leipzig, Germany
| | - Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig, 04103 Leipzig, Germany
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, 04103 Leipzig, Germany.
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49
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Jo AO, Ryskamp DA, Phuong TTT, Verkman AS, Yarishkin O, MacAulay N, Križaj D. TRPV4 and AQP4 Channels Synergistically Regulate Cell Volume and Calcium Homeostasis in Retinal Müller Glia. J Neurosci 2015; 35:13525-37. [PMID: 26424896 PMCID: PMC4588615 DOI: 10.1523/jneurosci.1987-15.2015] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 08/26/2015] [Accepted: 08/27/2015] [Indexed: 11/21/2022] Open
Abstract
Brain edema formation occurs after dysfunctional control of extracellular volume partly through impaired astrocytic ion and water transport. Here, we show that such processes might involve synergistic cooperation between the glial water channel aquaporin 4 (AQP4) and the transient receptor potential isoform 4 (TRPV4), a polymodal swelling-sensitive cation channel. In mouse retinas, TRPV4 colocalized with AQP4 in the end feet and radial processes of Müller astroglia. Genetic ablation of TRPV4 did not affect the distribution of AQP4 and vice versa. However, retinas from Trpv4(-/-) and Aqp4(-/-) mice exhibited suppressed transcription of genes encoding Trpv4, Aqp4, and the Kir4.1 subunit of inwardly rectifying potassium channels. Swelling and [Ca(2+)]i elevations evoked in Müller cells by hypotonic stimulation were antagonized by the selective TRPV4 antagonist HC-067047 (2-methyl-1-[3-(4-morpholinyl)propyl]-5-phenyl-N-[3-(trifluoromethyl)phenyl]-1H-pyrrole-3-carboxamide) or Trpv4 ablation. Elimination of Aqp4 suppressed swelling-induced [Ca(2+)]i elevations but only modestly attenuated the amplitude of Ca(2+) signals evoked by the TRPV4 agonist GSK1016790A [(N-((1S)-1-{[4-((2S)-2-{[(2,4-dichlorophenyl)sulfonyl]amino}-3-hydroxypropanoyl)-1-piperazinyl]carbonyl}-3-methylbutyl)-1-benzothiophene-2-carboxamide]. Glial cells lacking TRPV4 but not AQP4 showed deficits in hypotonic swelling and regulatory volume decrease. Functional synergy between TRPV4 and AQP4 during cell swelling was confirmed in the heterologously expressing Xenopus oocyte model. Importantly, when the swelling rate was osmotically matched for AQP4-positive and AQP4-negative oocytes, TRPV4 activation became independent of AQP4. We conclude that AQP4-mediated water fluxes promote the activation of the swelling sensor, whereas Ca(2+) entry through TRPV4 channels reciprocally modulates volume regulation, swelling, and Aqp4 gene expression. Therefore, TRPV4-AQP4 interactions constitute a molecular system that fine-tunes astroglial volume regulation by integrating osmosensing, calcium signaling, and water transport and, when overactivated, triggers pathological swelling. Significance statement: We characterize the physiological features of interactions between the astroglial swelling sensor transient receptor potential isoform 4 (TRPV4) and the aquaporin 4 (AQP4) water channel in retinal Müller cells. Our data reveal an elegant and complex set of mechanisms involving reciprocal interactions at the level of glial gene expression, calcium homeostasis, swelling, and volume regulation. Specifically, water influx through AQP4 drives calcium influx via TRPV4 in the glial end foot, which regulates expression of Aqp4 and Kir4.1 genes and facilitates the time course and amplitude of hypotonicity-induced swelling and regulatory volume decrease. We confirm the crucial facets of the signaling mechanism in heterologously expressing oocytes. These results identify the molecular mechanism that contributes to dynamic regulation of glial volume but also provide new insights into the pathophysiology of glial reactivity and edema formation.
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Affiliation(s)
- Andrew O Jo
- Department of Ophthalmology and Visual Sciences, Moran Eye Institute
| | - Daniel A Ryskamp
- Department of Ophthalmology and Visual Sciences, Moran Eye Institute, Interdepartmental Program in Neuroscience, and
| | - Tam T T Phuong
- Department of Ophthalmology and Visual Sciences, Moran Eye Institute
| | - Alan S Verkman
- Department of Medicine, University of California San Francisco, San Francisco, California 94143, and
| | - Oleg Yarishkin
- Department of Ophthalmology and Visual Sciences, Moran Eye Institute
| | - Nanna MacAulay
- Department of Cellular and Molecular Medicine, University of Copenhagen, 2200 Copenhagen, Denmark
| | - David Križaj
- Department of Ophthalmology and Visual Sciences, Moran Eye Institute, Interdepartmental Program in Neuroscience, and Department of Neurobiology and Anatomy, University of Utah School of Medicine, Salt Lake City, Utah 84132,
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50
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Grosche A, Hauser A, Lepper MF, Mayo R, von Toerne C, Merl-Pham J, Hauck SM. The Proteome of Native Adult Müller Glial Cells From Murine Retina. Mol Cell Proteomics 2015; 15:462-80. [PMID: 26324419 PMCID: PMC4739667 DOI: 10.1074/mcp.m115.052183] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Indexed: 12/26/2022] Open
Abstract
To date, the proteomic profiling of Müller cells, the dominant macroglia of the retina, has been hampered because of the absence of suitable enrichment methods. We established a novel protocol to isolate native, intact Müller cells from adult murine retinae at excellent purity which retain in situ morphology and are well suited for proteomic analyses. Two different strategies of sample preparation - an in StageTips (iST) and a subcellular fractionation approach including cell surface protein profiling were used for quantitative liquid chromatography-mass spectrometry (LC-MSMS) comparing Müller cell-enriched to depleted neuronal fractions. Pathway enrichment analyses on both data sets enabled us to identify Müller cell-specific functions which included focal adhesion kinase signaling, signal transduction mediated by calcium as second messenger, transmembrane neurotransmitter transport and antioxidant activity. Pathways associated with RNA processing, cellular respiration and phototransduction were enriched in the neuronal subpopulation. Proteomic results were validated for selected Müller cell genes by quantitative real time PCR, confirming the high expression levels of numerous members of the angiogenic and anti-inflammatory annexins and antioxidant enzymes (e.g. paraoxonase 2, peroxiredoxin 1, 4 and 6). Finally, the significant enrichment of antioxidant proteins in Müller cells was confirmed by measurements on vital retinal cells using the oxidative stress indicator CM-H2DCFDA. In contrast to photoreceptors or bipolar cells, Müller cells were most efficiently protected against H2O2-induced reactive oxygen species formation, which is in line with the protein repertoire identified in the proteomic profiling. Our novel approach to isolate intact glial cells from adult retina in combination with proteomic profiling enabled the identification of novel Müller glia specific proteins, which were validated as markers and for their functional impact in glial physiology. This provides the basis to allow the discovery of novel glial specializations and will enable us to elucidate the role of Müller cells in retinal pathologies — a topic still controversially discussed.
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Affiliation(s)
- Antje Grosche
- From the ‡Insitute of Human Genetics, University of Regensburg, D-93053 Regensburg, Germany;
| | - Alexandra Hauser
- From the ‡Insitute of Human Genetics, University of Regensburg, D-93053 Regensburg, Germany
| | - Marlen Franziska Lepper
- §Research Unit Protein Science, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), D-85764 Neuherberg, Germany
| | - Rebecca Mayo
- From the ‡Insitute of Human Genetics, University of Regensburg, D-93053 Regensburg, Germany
| | - Christine von Toerne
- §Research Unit Protein Science, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), D-85764 Neuherberg, Germany
| | - Juliane Merl-Pham
- §Research Unit Protein Science, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), D-85764 Neuherberg, Germany
| | - Stefanie M Hauck
- §Research Unit Protein Science, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), D-85764 Neuherberg, Germany
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