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Ahl M, Avdic U, Skoug C, Ali I, Chugh D, Johansson UE, Ekdahl CT. Immune response in the eye following epileptic seizures. J Neuroinflammation 2016; 13:155. [PMID: 27346214 PMCID: PMC4922060 DOI: 10.1186/s12974-016-0618-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 06/08/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Epileptic seizures are associated with an immune response in the brain. However, it is not known whether it can extend to remote areas of the brain, such as the eyes. Hence, we investigated whether epileptic seizures induce inflammation in the retina. METHODS Adult rats underwent electrically induced temporal status epilepticus, and the eyes were studied 6 h, 1, and 7 weeks later with biochemical and immunohistochemical analyses. An additional group of animals received CX3CR1 antibody intracerebroventricularly for 6 weeks after status epilepticus. RESULTS Biochemical analyses and immunohistochemistry revealed no increased cell death and unaltered expression of several immune-related cytokines and chemokines as well as no microglial activation, 6 h post-status epilepticus compared to non-stimulated controls. At 1 week, again, retinal cytoarchitecture appeared normal and there was no cell death or micro- or macroglial reaction, apart from a small decrease in interleukin-10. However, at 7 weeks, even if the cytoarchitecture remained normal and no ongoing cell death was detected, the numbers of microglia were increased ipsi- and contralateral to the epileptic focus. The microglia remained within the synaptic layers but often in clusters and with more processes extending into the outer nuclear layer. Morphological analyses revealed a decrease in surveying and an increase in activated microglia. In addition, increased levels of the chemokine KC/GRO and cytokine interleukin-1β were found. Furthermore, macroglial activation was noted in the inner retina. No alterations in numbers of phagocytic cells, infiltrating macrophages, or vascular pericytes were observed. Post-synaptic density-95 cluster intensity was reduced in the outer nuclear layer, reflecting seizure-induced synaptic changes without disrupted cytoarchitecture in areas with increased microglial activation. The retinal gliosis was decreased by a CX3CR1 immune modulation known to reduce gliosis within epileptic foci, suggesting a common immunological reaction. CONCLUSIONS Our results are the first evidence that epileptic seizures induce an immune response in the retina. It has a potential to become a novel non-invasive tool for detecting brain inflammation through the eyes.
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Affiliation(s)
- Matilda Ahl
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.,Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden
| | - Una Avdic
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.,Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden
| | - Cecilia Skoug
- Division of Ophthalmology, Department of Clinical Sciences, Lund University, SE-221 85, Lund, Sweden
| | - Idrish Ali
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.,Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden
| | - Deepti Chugh
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden.,Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden
| | - Ulrica Englund Johansson
- Division of Ophthalmology, Department of Clinical Sciences, Lund University, SE-221 85, Lund, Sweden
| | - Christine T Ekdahl
- Inflammation and Stem Cell Therapy Group, Division of Clinical Neurophysiology, Lund University, BMC A11, Sölvegatan 17, SE-221 84, Lund, Sweden. .,Lund Epilepsy Center, Lund University, SE-221 85, Lund, Sweden.
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52
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Friend or Foe? Resident Microglia vs Bone Marrow-Derived Microglia and Their Roles in the Retinal Degeneration. Mol Neurobiol 2016; 54:4094-4112. [PMID: 27318678 DOI: 10.1007/s12035-016-9960-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/06/2016] [Indexed: 01/10/2023]
Abstract
Microglia are immune cells in the central nervous system (CNS) that originate from the yolk sac in an embryo. The renewal of the microglia pool in the adult eye consists of two components. In addition to the self-proliferation of resident cells, microglia in the CNS also derive from the bone marrow (BM). BM-derived cells pass through the blood-brain barrier (BBB) or blood-retina barrier (BRB) and differentiate into microglia under specific conditions which involves a complex mechanism. Recent studies have widely investigated the role of resident microglia and BM-derived microglia in the retinal degenerative disease. Both two cell types play dual roles and share many similar functions. However, resident microglia tend to polarize to the M1 phenotype which is pro-inflammatory and neurotoxic, whereas BM-derived microglia mainly polarize to the neuroprotective M2 phenotype in retinal degeneration. The molecular mechanism that underlines the invasion of peripheral cells has led to extensive discussions. In addition to the BBB and BRB disruption, many signaling pathways are involved in this process. Based on these studies, we discuss the roles of these two types of microglia in retinal degeneration disease and the potential clinical application of BM-derived microglia, which may benefit future therapies.
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53
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Zabel MK, Zhao L, Zhang Y, Gonzalez SR, Ma W, Wang X, Fariss RN, Wong WT. Microglial phagocytosis and activation underlying photoreceptor degeneration is regulated by CX3CL1-CX3CR1 signaling in a mouse model of retinitis pigmentosa. Glia 2016; 64:1479-91. [PMID: 27314452 PMCID: PMC4958518 DOI: 10.1002/glia.23016] [Citation(s) in RCA: 130] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 05/20/2016] [Indexed: 12/20/2022]
Abstract
Retinitis pigmentosa (RP), a disease characterized by the progressive degeneration of mutation‐bearing photoreceptors, is a significant cause of incurable blindness in the young worldwide. Recent studies have found that activated retinal microglia contribute to photoreceptor demise via phagocytosis and proinflammatory factor production, however mechanisms regulating these contributions are not well‐defined. In this study, we investigate the role of CX3CR1, a microglia‐specific receptor, in regulating microglia‐mediated degeneration using the well‐established rd10 mouse model of RP. We found that in CX3CR1‐deficient (CX3CR1GFP/GFP) rd10 mice microglial infiltration into the photoreceptor layer was significantly augmented and associated with accelerated photoreceptor apoptosis and atrophy compared with CX3CR1‐sufficient (CX3CR1GFP/+) rd10 littermates. CX3CR1‐deficient microglia demonstrated increased phagocytosis as evidenced by (1) having increased numbers of phagosomes in vivo, (2) an increased rate of phagocytosis of fluorescent beads and photoreceptor cellular debris in vitro, and (3) increased photoreceptor phagocytosis dynamics on live cell imaging in retinal explants, indicating that CX3CR1 signaling in microglia regulates the phagocytic clearance of at‐risk photoreceptors. We also found that CX3CR1 deficiency in retinal microglia was associated with increased expression of inflammatory cytokines and microglial activation markers. Significantly, increasing CX3CL1‐CX3CR1 signaling in the rd10 retina via exogenous intravitreal delivery of recombinant CX3CL1 was effective in (1) decreasing microglial infiltration, phagocytosis and activation, and (2) improving structural and functional features of photoreceptor degeneration. These results indicate that CX3CL1‐CX3CR1 signaling is a molecular mechanism capable of modulating microglial‐mediated degeneration and represents a potential molecular target in therapeutic approaches to RP. GLIA 2016;64:1479–1491
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Affiliation(s)
- Matthew K Zabel
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Lian Zhao
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Yikui Zhang
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Shaimar R Gonzalez
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Wenxin Ma
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Xu Wang
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Robert N Fariss
- Biological Imaging Core, National Eye Institute, National Institutes of Health, Bethesda, Maryland
| | - Wai T Wong
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, Maryland
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54
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Madeira MH, Ortin-Martinez A, Nadal-Nícolas F, Ambrósio AF, Vidal-Sanz M, Agudo-Barriuso M, Santiago AR. Caffeine administration prevents retinal neuroinflammation and loss of retinal ganglion cells in an animal model of glaucoma. Sci Rep 2016; 6:27532. [PMID: 27270337 PMCID: PMC4897621 DOI: 10.1038/srep27532] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Accepted: 05/10/2016] [Indexed: 12/22/2022] Open
Abstract
Glaucoma is the second leading cause of blindness worldwide, being characterized by progressive optic nerve damage and loss of retinal ganglion cells (RGCs), accompanied by increased inflammatory response involving retinal microglial cells. The etiology of glaucoma is still unknown, and despite elevated intraocular pressure (IOP) being a major risk factor, the exact mechanisms responsible for RGC degeneration remain unknown. Caffeine, which is an antagonist of adenosine receptors, is the most widely consumed psychoactive drug in the world. Several evidences suggest that caffeine can attenuate the neuroinflammatory responses and afford protection upon central nervous system (CNS) injury. We took advantage of a well characterized animal model of glaucoma to investigate whether caffeine administration controls neuroinflammation and elicits neuroprotection. Caffeine or water were administered ad libitum and ocular hypertension (OHT) was induced by laser photocoagulation of the limbal veins in Sprague Dawley rats. Herein, we show that caffeine is able to partially decrease the IOP in ocular hypertensive animals. More importantly, we found that drinking caffeine prevented retinal microglia-mediated neuroinflammatory response and attenuated the loss of RGCs in animals with ocular hypertension (OHT). This study opens the possibility that caffeine or adenosine receptor antagonists might be a therapeutic option to manage RGC loss in glaucoma.
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Affiliation(s)
- Maria H Madeira
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal.,CNC.IBILI, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Arturo Ortin-Martinez
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia &Instituto Murciano de Investigacion Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Arrixaca), 30100 Murcia, Spain
| | - Francisco Nadal-Nícolas
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia &Instituto Murciano de Investigacion Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Arrixaca), 30100 Murcia, Spain
| | - António F Ambrósio
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal.,CNC.IBILI, University of Coimbra, 3004-504 Coimbra, Portugal.,Association for Innovation and Biomedical Research on Light and Image (AIBILI), 3000-548 Coimbra, Portugal
| | - Manuel Vidal-Sanz
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia &Instituto Murciano de Investigacion Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Arrixaca), 30100 Murcia, Spain
| | - Marta Agudo-Barriuso
- Departamento de Oftalmología, Facultad de Medicina, Universidad de Murcia &Instituto Murciano de Investigacion Biosanitaria Hospital Virgen de la Arrixaca (IMIB-Arrixaca), 30100 Murcia, Spain
| | - Ana Raquel Santiago
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal.,CNC.IBILI, University of Coimbra, 3004-504 Coimbra, Portugal.,Association for Innovation and Biomedical Research on Light and Image (AIBILI), 3000-548 Coimbra, Portugal
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55
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Lv B, Huo F, Zhu Z, Xu Z, Dang X, Chen T, Zhang T, Yang X. Crocin Upregulates CX3CR1 Expression by Suppressing NF-κB/YY1 Signaling and Inhibiting Lipopolysaccharide-Induced Microglial Activation. Neurochem Res 2016; 41:1949-57. [PMID: 27084772 DOI: 10.1007/s11064-016-1905-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 03/24/2016] [Accepted: 03/28/2016] [Indexed: 11/26/2022]
Abstract
Glaucoma is a group of neurodegenerative diseases characterized by the progressive loss of retinal ganglion cells (RGCs) and optic nerve fibers. Microglial activation has been shown to be deleterious to RGCs and may participate in the progression of glaucoma. Crocin, one of the major active ingredients in saffron, has been found to inhibit microglial activation. However, the mechanism remains unclear. The aim of this study was to investigate whether crocin can inhibit lipopolysaccharide (LPS)-induced microglial activation and to clarify the mechanisms involved. The influence of crocin on primary RGCs and LPS-stimulated BV2 microglial cells survival was determined by the MTT and lactate dehydrogenase assays, or by flow cytometry. BV2 cells were pretreated with various concentrations of crocin for 2 h followed by 1 μg/mL LPS stimulation. Microglial markers and pro-inflammatory mediators were assessed by real-time PCR, western blot and ELISA. Furthermore, CX3CR1 expression was detected and the underlying mechanism was examined. The concentrations of crocin ranged from 0.1 to 1 μM, and did not show any cytotoxicity in RGC and BV2 cells. After crocin pretreatment, the expression of microglial markers (CD11b and Iba-1) and pro-inflammatory mediators (iNOS, COX-2, IL-1β, and TNF-α) induced by LPS were significantly decreased in a dose-dependent manner. Additionally, CX3CR1 expression was remarkably increased by crocin via the suppression of NF-κB/Yin Yang 1 (YY1) signaling in BV2 cells. In conclusion, crocin effectively suppresses microglial activation and upregulates CX3CR1 expression by suppressing NF-κB/YY1 signaling.
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Affiliation(s)
- Bochang Lv
- Shaanxi Ophthalmic Medical Center, Xi'an No. 4 Hospital, Affiliated Guangren Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China
| | - Fuquan Huo
- Department of Physiology and Pathophysiology, Key Laboratory of Environment and Genes Related to Diseases, Ministry of Education, Xi'an Jiaotong University School of Medicine, Xi'an, 710061, People's Republic of China
| | - Zhongqiao Zhu
- Shaanxi Ophthalmic Medical Center, Xi'an No. 4 Hospital, Affiliated Guangren Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China
| | - Zhiguo Xu
- Shaanxi Ophthalmic Medical Center, Xi'an No. 4 Hospital, Affiliated Guangren Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China
| | - Xiaojie Dang
- Shaanxi Ophthalmic Medical Center, Xi'an No. 4 Hospital, Affiliated Guangren Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China
| | - Tao Chen
- Department of Anatomy, Histology and Embryology and K. K. Leung Brain Research Centre, Fourth Military Medical University, Xi'an, 710032, People's Republic of China
| | - Ting Zhang
- Department of Anatomy, Histology and Embryology and K. K. Leung Brain Research Centre, Fourth Military Medical University, Xi'an, 710032, People's Republic of China
| | - Xinguang Yang
- Shaanxi Ophthalmic Medical Center, Xi'an No. 4 Hospital, Affiliated Guangren Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, 710004, People's Republic of China.
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56
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Image processing methods to elucidate spatial characteristics of retinal microglia after optic nerve transection. Sci Rep 2016; 6:21816. [PMID: 26888347 PMCID: PMC4757874 DOI: 10.1038/srep21816] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 02/01/2016] [Indexed: 11/29/2022] Open
Abstract
Microglia are the mononuclear phagocytes with various functions in the central nervous system, and the morphologies of microglia imply the different stages and functions. In optical nerve transection model of the retina, the retrograde degeneration of retinal ganglion cells induces microglial activations to a unique morphology termed rod microglia. A few studies described the rod microglia in the cortex and retina; however, the spatial characteristic of rod microglia is not fully understood. In this study, we built a mathematical model to characterize the spatial trait of rod microglia. In addition, we developed a Matlab-based image processing pipeline that consists of log enhancement, image segmentation, mathematical morphology based cell detection, area calculation and angle analysis. This computer program provides researchers a powerful tool to quickly analyze the spatial trait of rod microglia.
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57
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Parajuli B, Horiuchi H, Mizuno T, Takeuchi H, Suzumura A. CCL11 enhances excitotoxic neuronal death by producing reactive oxygen species in microglia. Glia 2015; 63:2274-84. [PMID: 26184677 DOI: 10.1002/glia.22892] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2015] [Revised: 06/05/2015] [Accepted: 06/30/2015] [Indexed: 12/28/2022]
Abstract
The chemokine CCL11 (also known as eotaxin-1) is a potent eosinophil chemoattractant that mediates allergic diseases such as asthma, atopic dermatitis, and inflammatory bowel diseases. Previous studies demonstrated that concentrations of CCL11 are elevated in the sera and cerebrospinal fluids (CSF) of patients with neuroinflammatory disorders, including multiple sclerosis. Moreover, the levels of CCL11 in plasma and CSF increase with age, and CCL11 suppresses adult neurogenesis in the central nervous system (CNS), resulting in memory impairment. However, the precise source and function of CCL11 in the CNS are not fully understood. In this study, we found that activated astrocytes release CCL11, whereas microglia predominantly express the CCL11 receptor. CCL11 significantly promoted the migration of microglia, and induced microglial production of reactive oxygen species by upregulating nicotinamide adenine dinucleotide phosphate-oxidase 1 (NOX1), thereby promoting excitotoxic neuronal death. These effects were reversed by inhibition of NOX1. Our findings suggest that CCL11 released from activated astrocytes triggers oxidative stress via microglial NOX1 activation and potentiates glutamate-mediated neurotoxicity, which may be involved in the pathogenesis of various neurological disorders.
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Affiliation(s)
- Bijay Parajuli
- Department of Neuroimmunology, Research Institute of Environmental Medicine, Nagoya University, Chikusa-Ku, Nagoya, Japan
| | - Hiroshi Horiuchi
- Department of Neuroimmunology, Research Institute of Environmental Medicine, Nagoya University, Chikusa-Ku, Nagoya, Japan
| | - Tetsuya Mizuno
- Department of Neuroimmunology, Research Institute of Environmental Medicine, Nagoya University, Chikusa-Ku, Nagoya, Japan
| | - Hideyuki Takeuchi
- Department of Neuroimmunology, Research Institute of Environmental Medicine, Nagoya University, Chikusa-Ku, Nagoya, Japan
| | - Akio Suzumura
- Department of Neuroimmunology, Research Institute of Environmental Medicine, Nagoya University, Chikusa-Ku, Nagoya, Japan
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58
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Vecino E, Rodriguez FD, Ruzafa N, Pereiro X, Sharma SC. Glia-neuron interactions in the mammalian retina. Prog Retin Eye Res 2015; 51:1-40. [PMID: 26113209 DOI: 10.1016/j.preteyeres.2015.06.003] [Citation(s) in RCA: 512] [Impact Index Per Article: 56.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Revised: 05/18/2015] [Accepted: 06/02/2015] [Indexed: 02/07/2023]
Abstract
The mammalian retina provides an excellent opportunity to study glia-neuron interactions and the interactions of glia with blood vessels. Three main types of glial cells are found in the mammalian retina that serve to maintain retinal homeostasis: astrocytes, Müller cells and resident microglia. Müller cells, astrocytes and microglia not only provide structural support but they are also involved in metabolism, the phagocytosis of neuronal debris, the release of certain transmitters and trophic factors and K(+) uptake. Astrocytes are mostly located in the nerve fibre layer and they accompany the blood vessels in the inner nuclear layer. Indeed, like Müller cells, astrocytic processes cover the blood vessels forming the retinal blood barrier and they fulfil a significant role in ion homeostasis. Among other activities, microglia can be stimulated to fulfil a macrophage function, as well as to interact with other glial cells and neurons by secreting growth factors. This review summarizes the main functional relationships between retinal glial cells and neurons, presenting a general picture of the retina recently modified based on experimental observations. The preferential involvement of the distinct glia cells in terms of the activity in the retina is discussed, for example, while Müller cells may serve as progenitors of retinal neurons, astrocytes and microglia are responsible for synaptic pruning. Since different types of glia participate together in certain activities in the retina, it is imperative to explore the order of redundancy and to explore the heterogeneity among these cells. Recent studies revealed the association of glia cell heterogeneity with specific functions. Finally, the neuroprotective effects of glia on photoreceptors and ganglion cells under normal and adverse conditions will also be explored.
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Affiliation(s)
- Elena Vecino
- Department of Cell Biology and Histology, University of the Basque Country UPV/EHU, Leioa 48940, Vizcaya, Spain
| | - F David Rodriguez
- Department of Biochemistry and Molecular Biology, E-37007, University of Salamanca, Salamanca, Spain
| | - Noelia Ruzafa
- Department of Cell Biology and Histology, University of the Basque Country UPV/EHU, Leioa 48940, Vizcaya, Spain
| | - Xandra Pereiro
- Department of Cell Biology and Histology, University of the Basque Country UPV/EHU, Leioa 48940, Vizcaya, Spain
| | - Sansar C Sharma
- Department of Ophthalmology, Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, USA; IKERBASQUE, Basque Foundation for Science at Dept. Cell Biology and Histology, UPV/EHU, Spain
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59
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Madeira MH, Elvas F, Boia R, Gonçalves FQ, Cunha RA, Ambrósio AF, Santiago AR. Adenosine A2AR blockade prevents neuroinflammation-induced death of retinal ganglion cells caused by elevated pressure. J Neuroinflammation 2015; 12:115. [PMID: 26054642 PMCID: PMC4465153 DOI: 10.1186/s12974-015-0333-5] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 05/27/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Elevated intraocular pressure (IOP) is a major risk factor for glaucoma, a degenerative disease characterized by the loss of retinal ganglion cells (RGCs). There is clinical and experimental evidence that neuroinflammation is involved in the pathogenesis of glaucoma. Since the blockade of adenosine A2A receptor (A2AR) confers robust neuroprotection and controls microglia reactivity in the brain, we now investigated the ability of A2AR blockade to control the reactivity of microglia and neuroinflammation as well as RGC loss in retinal organotypic cultures exposed to elevated hydrostatic pressure (EHP) or lipopolysaccharide (LPS). METHODS Retinal organotypic cultures were either incubated with LPS (3 μg/mL), to elicit a pro-inflammatory response, or exposed to EHP (+70 mmHg), to mimic increased IOP, for 4 or 24 h, in the presence or absence of the A2AR antagonist SCH 58261 (50 nM). A2AR expression, microglial reactivity and neuroinflammatory response were evaluated by immunohistochemistry, quantitative PCR (qPCR) and enzyme-linked immunosorbent assay (ELISA). RGC loss was assessed by immunohistochemistry. In order to investigate the contribution of pro-inflammatory mediators to RGC loss, the organotypic retinal cultures were incubated with rabbit anti-tumour necrosis factor (TNF) (2 μg/mL) and goat anti-interleukin-1β (IL-1β) (1 μg/mL) antibodies. RESULTS We report that the A2AR antagonist (SCH 58261) prevented microglia reactivity, increase in pro-inflammatory mediators as well as RGC loss upon exposure to either LPS or EHP. Additionally, neutralization of TNF and IL-1β prevented RGC loss induced by LPS or EHP. CONCLUSIONS This work demonstrates that A2AR blockade confers neuroprotection to RGCs by controlling microglia-mediated retinal neuroinflammation and prompts the hypothesis that A2AR antagonists may be a novel therapeutic option to manage glaucomatous disorders.
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Affiliation(s)
- Maria H Madeira
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3004-548, Coimbra, Portugal. .,CNC.IBILI, University of Coimbra, 3004-517, Coimbra, Portugal.
| | - Filipe Elvas
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3004-548, Coimbra, Portugal.
| | - Raquel Boia
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3004-548, Coimbra, Portugal. .,CNC.IBILI, University of Coimbra, 3004-517, Coimbra, Portugal.
| | - Francisco Q Gonçalves
- CNC.IBILI, University of Coimbra, 3004-517, Coimbra, Portugal. .,CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517, Coimbra, Portugal.
| | - Rodrigo A Cunha
- CNC.IBILI, University of Coimbra, 3004-517, Coimbra, Portugal. .,CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517, Coimbra, Portugal. .,Faculty of Medicine, University of Coimbra, 3000-548, Coimbra, Portugal.
| | - António Francisco Ambrósio
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3004-548, Coimbra, Portugal. .,CNC.IBILI, University of Coimbra, 3004-517, Coimbra, Portugal. .,Association for Innovation and Biomedical Research on Light (AIBILI), 3000-548, Coimbra, Portugal.
| | - Ana Raquel Santiago
- Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, 3004-548, Coimbra, Portugal. .,CNC.IBILI, University of Coimbra, 3004-517, Coimbra, Portugal. .,Association for Innovation and Biomedical Research on Light (AIBILI), 3000-548, Coimbra, Portugal. .,Faculty of Medicine, University of Coimbra, 3000-548, Coimbra, Portugal. .,IBILI, Faculty of Medicine, University of Coimbra, Azinhaga de Santa Comba, 3004-548, Coimbra, Portugal.
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60
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Local proliferation is the main source of rod microglia after optic nerve transection. Sci Rep 2015; 5:10788. [PMID: 26035780 PMCID: PMC4649910 DOI: 10.1038/srep10788] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2015] [Accepted: 04/15/2015] [Indexed: 01/16/2023] Open
Abstract
Microglia are the resident phagocytic cells with various functions in the central nervous system, and the morphologies of microglia imply the different stages and functions. In optical nerve transection (ONT) model in the retina, the retrograde degeneration of retinal ganglion cells (RGCs) induces microglial activations to a unique morphology termed "rod" microglia. A few studies described the "rod" microglia in the cortex and retina; however, the function and origin of "rod" microglia are largely unknown. In the present study, we firstly studied the temporal appearance of "rod" microglia after ONT, and found the "rod" microglia emerge at approximately 7 days after ONT and peak during 14 to 21 days. Interestingly, the number of "rod" microglia remarkably decays after 6 weeks. Secondly, the "rod" microglia eliminate the degenerating RGC debris by phagocytosis. Moreover, we found the major source of "rod" microgliosis is local proliferation rather than the infiltration of peripheral monocytes/hematopoietic stem cells. We for the first time described the appearance of "rod" retinal microglia following optic nerve transection.
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61
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Abstract
Purpose of review The present review describes new advances in our understanding of the role of glial cells in the pathogenesis of glaucoma. It is becoming clear that retinal glia should not be studied in isolation in glaucoma because glia have dynamic and diverse interactions with a range of different cell types that could influence the disease process. Recent findings Microglial activity is modulated by signals from retinal ganglion cells and macroglia that influence RGC survival in various models of injury. New studies suggest that circulating monocytic populations may play a role in mediating the immune response to glaucoma. Astrocytes have been found to develop discrete localized processes that interact with a specific subset of retinal ganglion cells, possibly responding to the expression of phagocytic signals by stressed retinal ganglion cells. Summary Retinal glia constitute a highly versatile population that interacts with various cells to maintain homeostasis and limit disease. Defining the mechanisms that underlie glial communication could enable the development of more selective therapeutic targets, with great potential clinical applications.
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