151
|
Metabolomics and neuroanatomical evaluation of post-mortem changes in the hippocampus. Brain Struct Funct 2017; 222:2831-2853. [PMID: 28285370 PMCID: PMC5541081 DOI: 10.1007/s00429-017-1375-5] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 01/24/2017] [Indexed: 12/24/2022]
Abstract
Understanding the human brain is the ultimate goal in neuroscience, but this is extremely challenging in part due to the fact that brain tissue obtained from autopsy is practically the only source of normal brain tissue and also since changes at different levels of biological organization (genetic, molecular, biochemical, anatomical) occur after death due to multiple mechanisms. Here we used metabolomic and anatomical techniques to study the possible relationship between post-mortem time (PT)-induced changes that may occur at both the metabolomics and anatomical levels in the same brains. Our experiments have mainly focused on the hippocampus of the mouse. We found significant metabolomic changes at 2 h PT, whereas the integrity of neurons and glia, at the anatomical/ neurochemical level, was not significantly altered during the first 5 h PT for the majority of histological markers.
Collapse
|
152
|
Chinnery HR, McMenamin PG, Dando SJ. Macrophage physiology in the eye. Pflugers Arch 2017; 469:501-515. [DOI: 10.1007/s00424-017-1947-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 01/29/2017] [Accepted: 01/31/2017] [Indexed: 10/20/2022]
|
153
|
Microglia in the primate macula: specializations in microglial distribution and morphology with retinal position and with aging. Brain Struct Funct 2017; 222:2759-2771. [PMID: 28213784 DOI: 10.1007/s00429-017-1370-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 01/16/2017] [Indexed: 01/08/2023]
Abstract
Microglia, the principal resident immune cell in the retina, play constitutive roles in immune surveillance and synapse maintenance, and are also associated with retinal disease, including those occurring in the macula. Perspectives on retinal microglia function have derived largely from rodent models and how these relate to the macula-bearing primate retina is unclear. In this study, we examined microglial distribution and cellular morphology in the adult rhesus macaque retina, and performed comparative characterizations in three retinal locations along the center-to-periphery axis (parafoveal, macular, and the peripheral retina). We found that microglia density peaked in the parafoveal retina and decreased in the peripheral retina. Individual microglial morphology reflected macular specialization, with macular microglia demonstrating the largest and most complex dendritic arbors relative to other retinal locations. Comparing retinal microglia between young and middle-aged animals, microglial density increased in the macular, but not in the peripheral retina with age, while microglial morphology across all locations remained relatively unchanged. Our findings indicate that microglial distribution and morphology demonstrate regional specialization in the retina, correlating with gradients of other retinal cell types. As microglia are innate immune cells implicated in age-related macular diseases, age-related microglial changes may be related to the increased vulnerability of the aged macula to immune-related neurodegeneration.
Collapse
|
154
|
Stokes JA, Arbogast TE, Moya EA, Fu Z, Powell FL. Minocycline blocks glial cell activation and ventilatory acclimatization to hypoxia. J Neurophysiol 2017; 117:1625-1635. [PMID: 28100653 DOI: 10.1152/jn.00525.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 01/11/2017] [Accepted: 01/11/2017] [Indexed: 01/14/2023] Open
Abstract
Ventilatory acclimatization to hypoxia (VAH) is the time-dependent increase in ventilation, which persists upon return to normoxia and involves plasticity in both central nervous system respiratory centers and peripheral chemoreceptors. We investigated the role of glial cells in VAH in male Sprague-Dawley rats using minocycline, an antibiotic that inhibits microglia activation and has anti-inflammatory properties, and barometric pressure plethysmography to measure ventilation. Rats received either minocycline (45mg/kg ip daily) or saline beginning 1 day before and during 7 days of chronic hypoxia (CH, PiO2 = 70 Torr). Minocycline had no effect on normoxic control rats or the hypercapnic ventilatory response in CH rats, but minocycline significantly (P < 0.001) decreased ventilation during acute hypoxia in CH rats. However, minocycline administration during only the last 3 days of CH did not reverse VAH. Microglia and astrocyte activation in the nucleus tractus solitarius was quantified from 30 min to 7 days of CH. Microglia showed an active morphology (shorter and fewer branches) after 1 h of hypoxia and returned to the control state (longer filaments and extensive branching) after 4 h of CH. Astrocytes increased glial fibrillary acidic protein antibody immunofluorescent intensity, indicating activation, at both 4 and 24 h of CH. Minocycline had no effect on glia in normoxia but significantly decreased microglia activation at 1 h of CH and astrocyte activation at 24 h of CH. These results support a role for glial cells, providing an early signal for the induction but not maintenance of neural plasticity underlying ventilatory acclimatization to hypoxia.NEW & NOTEWORTHY The signals for neural plasticity in medullary respiratory centers underlying ventilatory acclimatization to chronic hypoxia are unknown. We show that chronic hypoxia activates microglia and subsequently astrocytes. Minocycline, an antibiotic that blocks microglial activation and has anti-inflammatory properties, also blocks astrocyte activation in respiratory centers during chronic hypoxia and ventilatory acclimatization. However, minocycline cannot reverse ventilatory acclimatization after it is established. Hence, glial cells may provide signals that initiate but do not sustain ventilatory acclimatization.
Collapse
Affiliation(s)
- Jennifer A Stokes
- Division of Physiology, Department of Medicine; University of California, San Diego, La Jolla, California
| | - Tara E Arbogast
- Division of Physiology, Department of Medicine; University of California, San Diego, La Jolla, California
| | - Esteban A Moya
- Division of Physiology, Department of Medicine; University of California, San Diego, La Jolla, California
| | - Zhenxing Fu
- Division of Physiology, Department of Medicine; University of California, San Diego, La Jolla, California
| | - Frank L Powell
- Division of Physiology, Department of Medicine; University of California, San Diego, La Jolla, California
| |
Collapse
|
155
|
Peña-Ortega F. Pharmacological Tools to Activate Microglia and their Possible use to Study Neural Network Patho-physiology. Curr Neuropharmacol 2017; 15:595-619. [PMID: 27697040 PMCID: PMC5543677 DOI: 10.2174/1570159x14666160928151546] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 08/05/2016] [Accepted: 09/26/2016] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Microglia are the resident immunocompetent cells of the CNS and also constitute a unique cell type that contributes to neural network homeostasis and function. Understanding microglia cell-signaling not only will reveal their diverse functions but also will help to identify pharmacological and non-pharmacological tools to modulate the activity of these cells. METHODS We undertook a search of bibliographic databases for peer-reviewed research literature to identify microglial activators and their cell-specificity. We also looked for their effects on neural network function and dysfunction. RESULTS We identified several pharmacological targets to modulate microglial function, which are more or less specific (with the proper control experiments). We also identified pharmacological targets that would require the development of new potent and specific modulators. We identified a wealth of evidence about the participation of microglia in neural network function and their alterations in pathological conditions. CONCLUSION The identification of specific microglia-activating signals provides experimental tools to modulate the activity of this heterogeneous cell type in order to evaluate its impact on other components of the nervous system, and it also helps to identify therapeutic approaches to ease some pathological conditions related to microglial dysfunction.
Collapse
Affiliation(s)
- Fernando Peña-Ortega
- Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, UNAM-Campus Juriquilla, México
| |
Collapse
|
156
|
Kalk NJ, Guo Q, Owen D, Cherian R, Erritzoe D, Gilmour A, Ribeiro AS, McGonigle J, Waldman A, Matthews P, Cavanagh J, McInnes I, Dar K, Gunn R, Rabiner EA, Lingford-Hughes AR. Decreased hippocampal translocator protein (18 kDa) expression in alcohol dependence: a [ 11C]PBR28 PET study. Transl Psychiatry 2017; 7:e996. [PMID: 28072413 PMCID: PMC5545729 DOI: 10.1038/tp.2016.264] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 11/02/2016] [Accepted: 11/13/2016] [Indexed: 01/05/2023] Open
Abstract
Repeated withdrawal from alcohol is clinically associated with progressive cognitive impairment. Microglial activation occurring during pre-clinical models of alcohol withdrawal is associated with learning deficits. We investigated whether there was microglial activation in recently detoxified alcohol-dependent patients (ADP), using [11C]PBR28 positron emission tomography (PET), selective for the 18kDa translocator protein (TSPO) highly expressed in activated microglia and astrocytes. We investigated the relationship between microglial activation and cognitive performance. Twenty healthy control (HC) subjects (45±13; M:F 14:6) and nine ADP (45±6, M:F 9:0) were evaluated. Dynamic PET data were acquired for 90 min following an injection of 331±15 MBq [11C]PBR28. Regional volumes of distribution (VT) for regions of interest (ROIs) identified a priori were estimated using a two-tissue compartmental model with metabolite-corrected arterial plasma input function. ADP had an ~20% lower [11C]PBR28 VT, in the hippocampus (F(1,24) 5.694; P=0.025), but no difference in VT in other ROIs. Hippocampal [11C]PBR28 VT was positively correlated with verbal memory performance in a combined group of HC and ADP (r=0.720, P<0.001), an effect seen in HC alone (r=0.738; P=0.001) but not in ADP. We did not find evidence for increased microglial activation in ADP, as seen pre-clinically. Instead, our findings suggest lower glial density or an altered activation state with lower TSPO expression. The correlation between verbal memory and [11C]PBR28 VT, raises the possibility that abnormalities of glial function may contribute to cognitive impairment in ADP.
Collapse
Affiliation(s)
- N J Kalk
- National Addictions Centre, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, London, UK,National Addictions Centre, Institute of Psychiatry, Psychology and Neuroscience, Kings College London, 4 Windsor Walk, London SE5 8BB, UK. E-mail:
| | - Q Guo
- Neuroimaging Department, Kings College London, London, UK,Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - D Owen
- Division of Brain Sciences, Imperial College London, London, UK
| | - R Cherian
- West London Mental Health NHS Trust, London, UK
| | - D Erritzoe
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - A Gilmour
- Centre for Infection, Inflammation and Immunity, University of Glasgow, Glasgow, UK
| | - A S Ribeiro
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - J McGonigle
- Centre for Neuropsychopharmacology, Imperial College London, London, UK
| | - A Waldman
- Division of Brain Sciences, Imperial College London, London, UK
| | - P Matthews
- Division of Brain Sciences, Imperial College London, London, UK
| | - J Cavanagh
- Institute of Health and Well-being, University of Glasgow, Glasgow, UK
| | - I McInnes
- Centre for Infection, Inflammation and Immunity, University of Glasgow, Glasgow, UK
| | - K Dar
- Central and North West London NHS Trust, London, UK
| | - R Gunn
- Imanova Limited, London, UK
| | | | | |
Collapse
|
157
|
Central Nervous System: (Immunological) Ivory Tower or Not? Neuropsychopharmacology 2017; 42:28-35. [PMID: 27402496 PMCID: PMC5143482 DOI: 10.1038/npp.2016.122] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Revised: 06/23/2016] [Accepted: 06/30/2016] [Indexed: 12/31/2022]
Abstract
The view of the nervous system being the victim of destructive inflammation during autoimmunity, degeneration, or injury has been rapidly changing. Recent studies are supporting the idea that the immune system provides support for the nervous system at various levels. Though cell patrolling through the nervous system parenchyma is limited compared with other tissues, immune cell presence within the central nervous system (CNS; microglia), as well as around it (in the meningeal spaces and choroid plexus) has been shown to be important for brain tissue maintenance and function. This review primarily explores recent findings concerning neuroimmune interactions and their mechanisms under homeostatic conditions.
Collapse
|
158
|
Ardura-Fabregat A, Boddeke EWGM, Boza-Serrano A, Brioschi S, Castro-Gomez S, Ceyzériat K, Dansokho C, Dierkes T, Gelders G, Heneka MT, Hoeijmakers L, Hoffmann A, Iaccarino L, Jahnert S, Kuhbandner K, Landreth G, Lonnemann N, Löschmann PA, McManus RM, Paulus A, Reemst K, Sanchez-Caro JM, Tiberi A, Van der Perren A, Vautheny A, Venegas C, Webers A, Weydt P, Wijasa TS, Xiang X, Yang Y. Targeting Neuroinflammation to Treat Alzheimer's Disease. CNS Drugs 2017; 31:1057-1082. [PMID: 29260466 PMCID: PMC5747579 DOI: 10.1007/s40263-017-0483-3] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Over the past few decades, research on Alzheimer's disease (AD) has focused on pathomechanisms linked to two of the major pathological hallmarks of extracellular deposition of beta-amyloid peptides and intra-neuronal formation of neurofibrils. Recently, a third disease component, the neuroinflammatory reaction mediated by cerebral innate immune cells, has entered the spotlight, prompted by findings from genetic, pre-clinical, and clinical studies. Various proteins that arise during neurodegeneration, including beta-amyloid, tau, heat shock proteins, and chromogranin, among others, act as danger-associated molecular patterns, that-upon engagement of pattern recognition receptors-induce inflammatory signaling pathways and ultimately lead to the production and release of immune mediators. These may have beneficial effects but ultimately compromise neuronal function and cause cell death. The current review, assembled by participants of the Chiclana Summer School on Neuroinflammation 2016, provides an overview of our current understanding of AD-related immune processes. We describe the principal cellular and molecular players in inflammation as they pertain to AD, examine modifying factors, and discuss potential future therapeutic targets.
Collapse
Affiliation(s)
- A. Ardura-Fabregat
- grid.5963.9Faculty of Medicine, Institute of Neuropathology, University of Freiburg, Freiburg, Germany
| | - E. W. G. M. Boddeke
- 0000 0004 0407 1981grid.4830.fDepartment of Neuroscience, Section Medical Physiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - A. Boza-Serrano
- 0000 0001 0930 2361grid.4514.4Experimental Neuroinflammation Laboratory, Department of Experimental Medical Sciences, Biomedical Centrum (BMC), Lund University, Lund, Sweden
| | - S. Brioschi
- grid.5963.9Department of Psychiatry and Psychotherapy, Medical Center University of Freiburg, Faculty of Medicine University of Freiburg, Freiburg, Germany
| | - S. Castro-Gomez
- 0000 0000 8786 803Xgrid.15090.3dDepartment of Neurodegenerative Disease and Gerontopsychiatry/Neurology, University of Bonn Medical Center, Sigmund-Freud Str. 25, 53127 Bonn, Germany
| | - K. Ceyzériat
- grid.457334.2Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Département de la Recherche Fondamentale (DRF), Institut de biologie François Jacob, MIRCen, 92260 Fontenay-aux-Roses, France ,0000 0001 2171 2558grid.5842.bNeurodegenerative Diseases Laboratory, Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, UMR 9199, F-92260 Fontenay-aux-Roses, France
| | - C. Dansokho
- 0000 0004 0438 0426grid.424247.3German Center for Neurodegenerative Diseases (DZNE), Sigmund Freud Str. 27, 53127 Bonn, Germany
| | - T. Dierkes
- 0000 0004 0438 0426grid.424247.3German Center for Neurodegenerative Diseases (DZNE), Sigmund Freud Str. 27, 53127 Bonn, Germany ,0000 0000 8786 803Xgrid.15090.3dBiomedical Centre, Institute of Innate Immunity, University Hospital Bonn, Sigmund-Freud-Str. 25, 53127 Bonn, Germany
| | - G. Gelders
- 0000 0001 0668 7884grid.5596.fDepartment of Neurosciences, Laboratory for Neurobiology and Gene Therapy, KU Leuven, Leuven, Belgium
| | - Michael T. Heneka
- 0000 0004 0438 0426grid.424247.3German Center for Neurodegenerative Diseases (DZNE), Sigmund Freud Str. 27, 53127 Bonn, Germany ,0000 0000 8786 803Xgrid.15090.3dDepartment of Neurodegenerative Disease and Gerontopsychiatry/Neurology, University of Bonn Medical Center, Sigmund-Freud Str. 25, 53127 Bonn, Germany
| | - L. Hoeijmakers
- 0000000084992262grid.7177.6Center for Neuroscience (SILS-CNS), Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - A. Hoffmann
- Department of Molecular Neurology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - L. Iaccarino
- grid.15496.3fVita-Salute San Raffaele University, Milan, Italy ,0000000417581884grid.18887.3eIn Vivo Human Molecular and Structural Neuroimaging Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - S. Jahnert
- 0000 0000 8786 803Xgrid.15090.3dDepartment of Neurodegenerative Disease and Gerontopsychiatry/Neurology, University of Bonn Medical Center, Sigmund-Freud Str. 25, 53127 Bonn, Germany
| | - K. Kuhbandner
- Department of Neurology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - G. Landreth
- 0000 0001 2287 3919grid.257413.6Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, IN 46202 USA
| | - N. Lonnemann
- 0000 0001 1090 0254grid.6738.aDepartment of Cellular Neurobiology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | | | - R. M. McManus
- 0000 0004 0438 0426grid.424247.3German Center for Neurodegenerative Diseases (DZNE), Sigmund Freud Str. 27, 53127 Bonn, Germany
| | - A. Paulus
- 0000 0001 0930 2361grid.4514.4Experimental Neuroinflammation Laboratory, Department of Experimental Medical Sciences, Biomedical Centrum (BMC), Lund University, Lund, Sweden
| | - K. Reemst
- 0000000084992262grid.7177.6Center for Neuroscience (SILS-CNS), Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - J. M. Sanchez-Caro
- 0000 0004 0438 0426grid.424247.3German Center for Neurodegenerative Diseases (DZNE), Sigmund Freud Str. 27, 53127 Bonn, Germany
| | - A. Tiberi
- grid.6093.cBio@SNS Laboratory, Scuola Normale Superiore, Piazza dei Cavalieri 7, 56126 Pisa, Italy
| | - A. Van der Perren
- 0000 0001 0668 7884grid.5596.fDepartment of Neurosciences, Laboratory for Neurobiology and Gene Therapy, KU Leuven, Leuven, Belgium
| | - A. Vautheny
- grid.457334.2Commissariat à l’Energie Atomique et aux Energies Alternatives (CEA), Département de la Recherche Fondamentale (DRF), Institut de biologie François Jacob, MIRCen, 92260 Fontenay-aux-Roses, France ,0000 0001 2171 2558grid.5842.bNeurodegenerative Diseases Laboratory, Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud, UMR 9199, F-92260 Fontenay-aux-Roses, France
| | - C. Venegas
- 0000 0000 8786 803Xgrid.15090.3dDepartment of Neurodegenerative Disease and Gerontopsychiatry/Neurology, University of Bonn Medical Center, Sigmund-Freud Str. 25, 53127 Bonn, Germany
| | - A. Webers
- 0000 0000 8786 803Xgrid.15090.3dDepartment of Neurodegenerative Disease and Gerontopsychiatry/Neurology, University of Bonn Medical Center, Sigmund-Freud Str. 25, 53127 Bonn, Germany
| | - P. Weydt
- 0000 0000 8786 803Xgrid.15090.3dDepartment of Neurodegenerative Disease and Gerontopsychiatry/Neurology, University of Bonn Medical Center, Sigmund-Freud Str. 25, 53127 Bonn, Germany
| | - T. S. Wijasa
- 0000 0004 0438 0426grid.424247.3German Center for Neurodegenerative Diseases (DZNE), Sigmund Freud Str. 27, 53127 Bonn, Germany
| | - X. Xiang
- 0000 0004 1936 973Xgrid.5252.0Biomedical Center (BMC), Biochemistry, Ludwig-Maximilians-University Munich, 81377 Munich, Germany ,0000 0004 1936 973Xgrid.5252.0Graduate School of Systemic Neuroscience, Ludwig-Maximilians-University, Munich, 82152 Munich, Germany
| | - Y. Yang
- 0000 0001 0930 2361grid.4514.4Experimental Neuroinflammation Laboratory, Department of Experimental Medical Sciences, Biomedical Centrum (BMC), Lund University, Lund, Sweden
| |
Collapse
|
159
|
Role of glutamate receptors and glial cells in the pathophysiology of treatment-resistant depression. Prog Neuropsychopharmacol Biol Psychiatry 2016; 70:117-26. [PMID: 27046518 DOI: 10.1016/j.pnpbp.2016.03.009] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2016] [Revised: 03/27/2016] [Accepted: 03/29/2016] [Indexed: 02/07/2023]
Abstract
Treatment-resistant depression (TRD) causes substantial socioeconomic burden. Although a consensus on the definition of TRD has not yet been reached, it is certain that classic monoaminergic antidepressants are ineffective for TRD. One decade ago, many researchers found ketamine, an N-methyl-d-aspartate receptor (NMDAR) antagonist, to be an alternative to classic monoaminergic antidepressants. The major mechanisms of action of ketamine rapidly induce synaptogenesis in the brain-derived neurotrophic factor (BDNF) pathway. Although excessive glutamatergic neurotransmission and consequent excitotoxicity were considered a major cause of TRD, recent evidence suggests that the extrasynaptic glutamatergic receptor signal pathway mainly contributes to the detrimental effects of TRD. Glial cells such as microglia and astrocytes, early life adversity, and glucocorticoid receptor dysfunction participate in complex cross-talk. An appropriate reuptake of glutamate at the astrocyte is crucial for preventing 'spill-over' of synaptic glutamate and binding to the extrasynaptic NMDA receptor. Excessive microglial activation and the inflammatory process cause astrocyte glutamatergic dysfunction, which in turn activates microglial function. Early life adversity and glucocorticoid receptor dysfunction result in vulnerability to stress in adulthood. A maladaptive response to stress leads to increased glutamatergic release and pro-inflammatory cytokines, which then activate microglia. However, since the role of inflammatory mediators such as pro-inflammatory cytokines is not specific for depression, more disease-specific mechanisms should be identified. Last, although much research has focused on ketamine as an alternative antidepressant for TRD, its long-lasting effectiveness and adverse events have not been rigorously demonstrated. Additionally, evidence suggests that substantial brain abnormalities develop in ketamine abusers. Thus, more investigations for ketamine and other novel glutamatergic agents are needed.
Collapse
|
160
|
Mecha M, Carrillo-Salinas F, Feliú A, Mestre L, Guaza C. Microglia activation states and cannabinoid system: Therapeutic implications. Pharmacol Ther 2016; 166:40-55. [DOI: 10.1016/j.pharmthera.2016.06.011] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/08/2016] [Indexed: 12/16/2022]
|
161
|
Gajardo-Gómez R, Labra VC, Orellana JA. Connexins and Pannexins: New Insights into Microglial Functions and Dysfunctions. Front Mol Neurosci 2016; 9:86. [PMID: 27713688 PMCID: PMC5031785 DOI: 10.3389/fnmol.2016.00086] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/05/2016] [Indexed: 12/11/2022] Open
Abstract
Under physiological conditions, microglia adopt a resting phenotype associated with the production of anti-inflammatory and neurotrophic factors. In response to a wide variety of insults, these cells shift to an activated phenotype that is necessary for the proper restoration of brain homeostasis. However, when the intensity of a threat is relatively high, microglial activation worsens the progression of damage rather than providing protection, with potentially significant consequences for neuronal survival. Coordinated interactions among microglia and other brain cells, including astrocytes and neurons, are critical for the development of timely and optimal inflammatory responses in the brain parenchyma. Tissue synchronization is in part mediated by connexins and pannexins, which are protein families that form different plasma membrane channels to communicate with neighboring cells. Gap junction channels (which are exclusively formed by connexins in vertebrates) connect the cytoplasm of contacting cells to coordinate electrical and metabolic coupling. Hemichannels (HCs) and pannexons (which are formed by connexins and pannexins, respectively) communicate the intra- and extracellular compartments and serve as diffusion pathways for the exchange of ions and small molecules. In this review article, we discuss the available evidence concerning the functional expression and regulation of connexin- and pannexin-based channels in microglia and their contributions to microglial function and dysfunction. Specifically, we focus on the possible implications of these channels in microglia-to-microglia, microglia-to-astrocyte and neuron-to-microglia interactions in the inflamed brain.
Collapse
Affiliation(s)
- Rosario Gajardo-Gómez
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Valeria C Labra
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| |
Collapse
|
162
|
Multitasking Microglia and Alzheimer's Disease: Diversity, Tools and Therapeutic Targets. J Mol Neurosci 2016; 60:390-404. [PMID: 27660215 DOI: 10.1007/s12031-016-0825-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2016] [Accepted: 08/17/2016] [Indexed: 01/08/2023]
Abstract
Given the importance of microglia to inflammatory, phagocytic and synaptic modulatory processes, their function is vital in physiological and pathological brain. The impairment of microglia in Alzheimer's disease has been demonstrated on genetic, epigenetic, transcriptional and functional levels using unbiased systems level approaches. Recent studies have highlighted the immense phenotypic diversity of microglia, including the ability to adopt distinct and dynamic phenotypes in ageing and disease. We review the origins and functions of healthy microglia and the established and emerging models and techniques available for their study. Furthermore, we highlight recent advances on the role, heterogeneity and dysfunction of microglia in Alzheimer's disease and discuss the potential for therapeutic interventions targeting microglia. Microglia-selective molecular fingerprints will guide detailed functional analysis of microglial subsets and may aid in the development of therapies specifically targeting microglia.
Collapse
|
163
|
Andreasson KI, Bachstetter AD, Colonna M, Ginhoux F, Holmes C, Lamb B, Landreth G, Lee DC, Low D, Lynch MA, Monsonego A, O’Banion MK, Pekny M, Puschmann T, Russek-Blum N, Sandusky LA, Selenica MLB, Takata K, Teeling J, Town T, Van Eldik LJ, Russek-Blum N, Monsonego A, Low D, Takata K, Ginhoux F, Town T, O’Banion MK, Lamb B, Colonna M, Landreth G, Andreasson KI, Sandusky LA, Selenica MLB, Lee DC, Holmes C, Teeling J, Lynch MA, Van Eldik LJ, Bachstetter AD, Pekny M, Puschmann T. Targeting innate immunity for neurodegenerative disorders of the central nervous system. J Neurochem 2016; 138:653-93. [PMID: 27248001 PMCID: PMC5433264 DOI: 10.1111/jnc.13667] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/01/2016] [Accepted: 04/30/2016] [Indexed: 12/21/2022]
Abstract
Neuroinflammation is critically involved in numerous neurodegenerative diseases, and key signaling steps of innate immune activation hence represent promising therapeutic targets. This mini review series originated from the 4th Venusberg Meeting on Neuroinflammation held in Bonn, Germany, 7-9th May 2015, presenting updates on innate immunity in acute brain injury and chronic neurodegenerative disorders, such as traumatic brain injury and Alzheimer disease, on the role of astrocytes and microglia, as well as technical developments that may help elucidate neuroinflammatory mechanisms and establish clinical relevance. In this meeting report, a brief overview of physiological and pathological microglia morphology is followed by a synopsis on PGE2 receptors, insights into the role of arginine metabolism and further relevant aspects of neuroinflammation in various clinical settings, and concluded by a presentation of technical challenges and solutions when working with microglia and astrocyte cultures. Microglial ontogeny and induced pluripotent stem cell-derived microglia, advances of TREM2 signaling, and the cytokine paradox in Alzheimer's disease are further contributions to this article. Neuroinflammation is critically involved in numerous neurodegenerative diseases, and key signaling steps of innate immune activation hence represent promising therapeutic targets. This mini review series originated from the 4th Venusberg Meeting on Neuroinflammation held in Bonn, Germany, 7-9th May 2015, presenting updates on innate immunity in acute brain injury and chronic neurodegenerative disorders, such as traumatic brain injury and Alzheimer's disease, on the role of astrocytes and microglia, as well as technical developments that may help elucidate neuroinflammatory mechanisms and establish clinical relevance. In this meeting report, a brief overview on physiological and pathological microglia morphology is followed by a synopsis on PGE2 receptors, insights into the role of arginine metabolism and further relevant aspects of neuroinflammation in various clinical settings, and concluded by a presentation of technical challenges and solutions when working with microglia cultures. Microglial ontogeny and induced pluripotent stem cell-derived microglia, advances of TREM2 signaling, and the cytokine paradox in Alzheimer's disease are further contributions to this article.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Niva Russek-Blum
- The Dead Sea and Arava Science Center, Central Arava Branch, Yair Station, Hazeva, Israel
| | - Alon Monsonego
- The Shraga Segal Dept. of Microbiology, Immunology and Genetics, The Faculty of Health Sciences: The National Institute of Biotechnology in the Negev, and Zlotowski Center for Neuroscience, Ben-Gurion University, Beer-Sheva 84105, Israel
| | - Donovan Low
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore
| | - Kazuyuki Takata
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore
- Department of Clinical and Translational Physiology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Florent Ginhoux
- Singapore Immunology Network (SIgN), Agency for Science, Technology and Research (A*STAR), Singapore
| | - Terrence Town
- Departments of Physiology and Biophysics, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089,
| | - M. Kerry O’Banion
- Departments of Neuroscience and Neurology, Del Monte Neuromedicine Institute, University of Rochester School of Medicine & Dentistry, Rochester, NY 14642,
| | - Bruce Lamb
- Department of Neurosciences, Cleveland Clinic, Cleveland, OH 44106
| | - Marco Colonna
- Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110
| | - Gary Landreth
- Department of Neurosciences, Case Western Reserve University 44106
| | - Katrin I. Andreasson
- Department of Neurology and Neurological Sciences, Stanford Neuroscience Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Leslie A. Sandusky
- USF Health Byrd Alzheimer’s Institute, Tampa, FL 33613
- College of Pharmacy & Pharmaceutical Sciences, Tampa, FL 33613
| | - Maj-Linda B. Selenica
- USF Health Byrd Alzheimer’s Institute, Tampa, FL 33613
- College of Pharmacy & Pharmaceutical Sciences, Tampa, FL 33613
| | - Daniel C. Lee
- USF Health Byrd Alzheimer’s Institute, Tampa, FL 33613
- College of Pharmacy & Pharmaceutical Sciences, Tampa, FL 33613
| | - Clive Holmes
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 7YD, United Kingdom
| | - Jessica Teeling
- Centre for Biological Sciences, University of Southampton, Southampton General Hospital, Tremona Road, Southampton, SO16 7YD, United Kingdom
| | | | | | | | - Milos Pekny
- Center for Brain Repair and Rehabilitation, Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, SE-405 30 Gothenburg, Sweden
- Florey Institute of Neuroscience and Mental Health, Parkville, Victoria, Australia
- Hunter Medical Research Institute, University of Newcastle, New South Wales, Australia
| | - Till Puschmann
- Center for Brain Repair and Rehabilitation, Department of Clinical Neuroscience and Rehabilitation, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, SE-405 30 Gothenburg, Sweden
| |
Collapse
|
164
|
Macht VA. Neuro-immune interactions across development: A look at glutamate in the prefrontal cortex. Neurosci Biobehav Rev 2016; 71:267-280. [PMID: 27593444 DOI: 10.1016/j.neubiorev.2016.08.039] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 07/26/2016] [Accepted: 08/31/2016] [Indexed: 02/07/2023]
Abstract
Although the primary role for the immune system is to respond to pathogens, more recently, the immune system has been demonstrated to have a critical role in signaling developmental events. Of particular interest for this review is how immunocompetent microglia and astrocytes interact with glutamatergic systems to influence the development of neural circuits in the prefrontal cortex (PFC). Microglia are the resident macrophages of the brain, and astrocytes mediate both glutamatergic uptake and coordinate with microglia to respond to the general excitatory state of the brain. Cross-talk between microglia, astrocytes, and glutamatergic neurons forms a quad-partite synapse, and this review argues that interactions within this synapse have critical implications for the maturation of PFC-dependent cognitive function. Similarly, understanding developmental shifts in immune signaling may help elucidate variations in sensitivities to developmental disruptions.
Collapse
Affiliation(s)
- Victoria A Macht
- University of South Carolina, 1512 Pendleton St., Department of Psychology, Columbia, SC 29208, United States.
| |
Collapse
|
165
|
Requirement for Microglia for the Maintenance of Synaptic Function and Integrity in the Mature Retina. J Neurosci 2016; 36:2827-42. [PMID: 26937019 DOI: 10.1523/jneurosci.3575-15.2016] [Citation(s) in RCA: 135] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED Microglia, the principal resident immune cell of the CNS, exert significant influence on neurons during development and in pathological situations. However, if and how microglia contribute to normal neuronal function in the mature uninjured CNS is not well understood. We used the model of the adult mouse retina, a part of the CNS amenable to structural and functional analysis, to investigate the constitutive role of microglia by depleting microglia from the retina in a sustained manner using genetic methods. We discovered that microglia are not acutely required for the maintenance of adult retinal architecture, the survival of retinal neurons, or the laminar organization of their dendritic and axonal compartments. However, sustained microglial depletion results in the degeneration of photoreceptor synapses in the outer plexiform layer, leading to a progressive functional deterioration in retinal light responses. Our results demonstrate that microglia are constitutively required for the maintenance of synaptic structure in the adult retina and for synaptic transmission underlying normal visual function. Our findings on constitutive microglial function are relevant in understanding microglial contributions to pathology and in the consideration of therapeutic interventions that reduce or perturb constitutive microglial function. SIGNIFICANCE STATEMENT Microglia, the principal resident immune cell population in the CNS, has been implicated in diseases in the brain and retina. However, how they contribute to the everyday function of the CNS is unclear. Using the model of the adult mouse retina, we examined the constitutive role of microglia by depleting microglia from the retina. We found that in the absence of microglia, retinal neurons did not undergo overt cell death or become structurally disorganized in their processes. However, connections between neurons called synapses begin to break down, leading to a decreased ability of the retina to transmit light responses. Our results indicate that retinal microglia contribute constitutively to the maintenance of synapses underlying healthy vision.
Collapse
|
166
|
Gellner AK, Reis J, Fritsch B. Glia: A Neglected Player in Non-invasive Direct Current Brain Stimulation. Front Cell Neurosci 2016; 10:188. [PMID: 27551261 PMCID: PMC4976108 DOI: 10.3389/fncel.2016.00188] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 07/19/2016] [Indexed: 12/21/2022] Open
Abstract
Non-invasive electrical brain stimulation by application of direct current (DCS) promotes plasticity in neuronal networks in vitro and in in vivo. This effect has been mainly attributed to the direct modulation of neurons. Glia represents approximately 50% of cells in the brain. Glial cells are electrically active and participate in synaptic plasticity. Despite of that, effects of DCS on glial structures and on interaction with neurons are only sparsely investigated. In this perspectives article we review the current literature, present own dose response data and provide a framework for future research from two points of view: first, the direct effects of DCS on glia and second, the contribution of glia to DCS related neuronal plasticity.
Collapse
Affiliation(s)
| | - Janine Reis
- Department of Neurology, University Hospital Freiburg Freiburg, Germany
| | - Brita Fritsch
- Department of Neurology, University Hospital Freiburg Freiburg, Germany
| |
Collapse
|
167
|
Microglial P2Y12 receptors regulate microglial activation and surveillance during neuropathic pain. Brain Behav Immun 2016; 55:82-92. [PMID: 26576724 PMCID: PMC4864135 DOI: 10.1016/j.bbi.2015.11.007] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 10/15/2015] [Accepted: 11/09/2015] [Indexed: 11/20/2022] Open
Abstract
Microglial cells are critical in the pathogenesis of neuropathic pain and several microglial receptors have been proposed to mediate this process. Of these receptors, the P2Y12 receptor is a unique purinergic receptor that is exclusively expressed by microglia in the central nervous system (CNS). In this study, we set forth to investigate the role of P2Y12 receptors in microglial electrophysiological and morphological (static and dynamic) activation during spinal nerve transection (SNT)-induced neuropathic pain in mice. First, we found that a genetic deficiency of the P2Y12 receptor (P2Y12(-/-) mice) ameliorated pain hypersensitivities during the initiation phase of neuropathic pain. Next, we characterised both the electrophysiological and morphological properties of microglia in the superficial spinal cord dorsal horn following SNT injury. We show dramatic alterations including a peak at 3days post injury in microglial electrophysiology while high resolution two-photon imaging revealed significant changes of both static and dynamic microglial morphological properties by 7days post injury. Finally, in P2Y12(-/-) mice, these electrophysiological and morphological changes were ameliorated suggesting roles for P2Y12 receptors in SNT-induced microglial activation. Our results therefore indicate that P2Y12 receptors regulate microglial electrophysiological as well as static and dynamic microglial properties after peripheral nerve injury, suggesting that the microglial P2Y12 receptor could be a potential therapeutic target for the treatment of neuropathic pain.
Collapse
|
168
|
Abstract
Microglia constitute the powerhouse of the innate immune system in the brain. It is now widely accepted that they are monocytic-derived cells that infiltrate the developing brain at the early embryonic stages, and acquire a resting phenotype characterized by the presence of dense branching processes, called ramifications. Microglia use these dynamic ramifications as sentinels to sense and detect any occurring alteration in brain homeostasis. Once a danger signal is detected, such as molecular factors associated to brain damage or infection, they get activated by acquiring a less ramified phenotype, and mount adequate responses that range from phagocyting cell debris to secreting inflammatory and trophic factors. Here, we review the origin of microglia and we summarize the main molecular signals involved in controlling their function under physiological conditions. In addition, their implication in the pathogenesis of multiple sclerosis and stress is discussed.
Collapse
Affiliation(s)
- Ayman ElAli
- Neuroscience Laboratory, CHU de Québec Research Center (CHUL), Department of Psychiatry and Neuroscience, Faculty of Medicine, Laval University Quebec, CA, Canada
| | - Serge Rivest
- Neuroscience Laboratory, CHU de Québec Research Center (CHUL), Department of Molecular Medicine, Faculty of Medicine, Laval University Quebec, CA, Canada
| |
Collapse
|
169
|
Liu H, Leak RK, Hu X. Neurotransmitter receptors on microglia. Stroke Vasc Neurol 2016; 1:52-58. [PMID: 28959464 PMCID: PMC5435193 DOI: 10.1136/svn-2016-000012] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 04/29/2016] [Accepted: 04/30/2016] [Indexed: 12/21/2022] Open
Abstract
As the resident immune cells in the central nervous system, microglia have long been hypothesised to promote neuroinflammation and exacerbate neurotoxicity. However, this traditional view has undergone recent revision as evidence has accumulated that microglia exert beneficial and detrimental effects depending on activation status, polarisation phenotype and cellular context. A variety of neurotransmitter receptors are expressed on microglia and help mediate the bidirectional communication between neurons and microglia. Here we review data supporting the importance of neurotransmitter receptors on microglia, with a special emphasis on glutamate, γ-aminobutyric acid (GABA), norepinephrine, cannabinoid and acetylcholine receptors. We summarise evidence favouring a significant role for neurotransmitter receptors in modulating microglial activation, phagocytic clearance and phenotypic polarisation. Elucidating the effects of neurotransmitter receptors on microglia and dissecting the underlying mechanisms may help accelerate the discovery of novel drugs that tap the therapeutic potential of microglia.
Collapse
Affiliation(s)
- Huan Liu
- Center of Cerebrovascular Disease Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Rehana K Leak
- Division of Pharmaceutical Sciences, Duquesne University, Pittsburgh, Pennsylvania, USA
| | - Xiaoming Hu
- Center of Cerebrovascular Disease Research, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| |
Collapse
|
170
|
Microglial Contact Prevents Excess Depolarization and Rescues Neurons from Excitotoxicity. eNeuro 2016; 3:eN-NWR-0004-16. [PMID: 27390772 PMCID: PMC4916329 DOI: 10.1523/eneuro.0004-16.2016] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 04/29/2016] [Accepted: 05/18/2016] [Indexed: 12/20/2022] Open
Abstract
Microglia survey and directly contact neurons in both healthy and damaged brain, but the mechanisms and functional consequences of these contacts are not yet fully elucidated. Combining two-photon imaging and patch clamping, we have developed an acute experimental model for studying the role of microglia in CNS excitotoxicity induced by neuronal hyperactivity. Our model allows us to simultaneously examine the effects of repetitive supramaximal stimulation on axonal morphology, neuronal membrane potential, and microglial migration, using cortical brain slices from Iba-1 eGFP mice. We demonstrate that microglia exert an acute and highly localized neuroprotective action under conditions of neuronal hyperactivity. Evoking repetitive action potentials in individual layer 2/3 pyramidal neurons elicited swelling of axons, but not dendrites, which was accompanied by a large, sustained depolarization of soma membrane potential. Microglial processes migrated to these swollen axons in a mechanism involving both ATP and glutamate release via volume-activated anion channels. This migration was followed by intensive microglial wrapping of affected axons and, in some cases, the removal of axonal debris that induced a rapid soma membrane repolarization back to resting potentials. When the microglial migration was pharmacologically blocked, the activity-induced depolarization continued until cell death ensued, demonstrating that the microglia–axon contact served to prevent pathological depolarization of the soma and maintain neuronal viability. This is a novel aspect of microglia surveillance: detecting, wrapping, and rescuing neuronal soma from damage due to excessive activity.
Collapse
|
171
|
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
Collapse
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
| |
Collapse
|
172
|
Wohleb ES, Franklin T, Iwata M, Duman RS. Integrating neuroimmune systems in the neurobiology of depression. Nat Rev Neurosci 2016; 17:497-511. [PMID: 27277867 DOI: 10.1038/nrn.2016.69] [Citation(s) in RCA: 405] [Impact Index Per Article: 50.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Data from clinical and preclinical studies indicate that immune dysregulation, specifically of inflammatory processes, is associated with symptoms of major depressive disorder (MDD). In particular, increased levels of circulating pro-inflammatory cytokines and concomitant activation of brain-resident microglia can lead to depressive behavioural symptoms. Repeated exposure to psychological stress has a profound impact on peripheral immune responses and perturbs the function of brain microglia, which may contribute to neurobiological changes underlying MDD. Here, we review these findings and discuss ongoing studies examining neuroimmune mechanisms that influence neuronal activity as well as synaptic plasticity. Interventions targeting immune-related cellular and molecular pathways may benefit subsets of MDD patients with immune dysregulation.
Collapse
Affiliation(s)
- Eric S Wohleb
- Departments of Psychiatry and Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06519, USA
| | - Tina Franklin
- Departments of Psychiatry and Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06519, USA
| | - Masaaki Iwata
- Division of Neuropsychiatry, Department of Brain and Neurosciences, Tottori University Faculty of Medicine, 86 Nishi-cho, Yonago, Tottori 683-8503, Japan
| | - Ronald S Duman
- Departments of Psychiatry and Neurobiology, Yale University School of Medicine, New Haven, Connecticut 06519, USA
| |
Collapse
|
173
|
Zhao L, Zabel MK, Wang X, Ma W, Shah P, Fariss RN, Qian H, Parkhurst CN, Gan WB, Wong WT. Microglial phagocytosis of living photoreceptors contributes to inherited retinal degeneration. EMBO Mol Med 2016; 7:1179-97. [PMID: 26139610 PMCID: PMC4568951 DOI: 10.15252/emmm.201505298] [Citation(s) in RCA: 298] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Retinitis pigmentosa, caused predominantly by mutations in photoreceptor genes, currently lacks comprehensive treatment. We discover that retinal microglia contribute non-cell autonomously to rod photoreceptor degeneration by primary phagocytosis of living rods. Using rd10 mice, we found that the initiation of rod degeneration is accompanied by early infiltration of microglia, upregulation of phagocytic molecules in microglia, and presentation of “eat-me” signals on mutated rods. On live-cell imaging, infiltrating microglia interact dynamically with photoreceptors via motile processes and engage in rapid phagocytic engulfment of non-apoptotic rods. Microglial contribution to rod demise is evidenced by morphological and functional amelioration of photoreceptor degeneration following genetic ablation of retinal microglia. Molecular inhibition of microglial phagocytosis using the vitronectin receptor antagonist cRGD also improved morphological and functional parameters of degeneration. Our findings highlight primary microglial phagocytosis as a contributing mechanism underlying cell death in retinitis pigmentosa and implicate microglia as a potential cellular target for therapy.
Collapse
Affiliation(s)
- Lian Zhao
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye institute National Institutes of Health, Bethesda, MD, USA
| | - Matthew K Zabel
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye institute National Institutes of Health, Bethesda, MD, USA
| | - Xu Wang
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye institute National Institutes of Health, Bethesda, MD, USA
| | - Wenxin Ma
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye institute National Institutes of Health, Bethesda, MD, USA
| | - Parth Shah
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye institute National Institutes of Health, Bethesda, MD, USA
| | - Robert N Fariss
- Biological Imaging Core, National Eye institute National Institutes of Health, Bethesda, MD, USA
| | - Haohua Qian
- Visual Function Core, National Eye institute National Institutes of Health, Bethesda, MD, USA
| | - Christopher N Parkhurst
- Department of Neuroscience and Physiology, Skirball Institute New York University School of Medicine, New York, NY, USA
| | - Wen-Biao Gan
- Department of Neuroscience and Physiology, Skirball Institute New York University School of Medicine, New York, NY, USA
| | - Wai T Wong
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye institute National Institutes of Health, Bethesda, MD, USA
| |
Collapse
|
174
|
Tay TL, Savage JC, Hui CW, Bisht K, Tremblay MÈ. Microglia across the lifespan: from origin to function in brain development, plasticity and cognition. J Physiol 2016; 595:1929-1945. [PMID: 27104646 DOI: 10.1113/jp272134] [Citation(s) in RCA: 352] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 03/15/2016] [Indexed: 12/11/2022] Open
Abstract
Microglia are the only immune cells that permanently reside in the central nervous system (CNS) alongside neurons and other types of glial cells. The past decade has witnessed a revolution in our understanding of their roles during normal physiological conditions. Cutting-edge techniques revealed that these resident immune cells are critical for proper brain development, actively maintain health in the mature brain, and rapidly adapt their function to physiological or pathophysiological needs. In this review, we highlight recent studies on microglial origin (from the embryonic yolk sac) and the factors regulating their differentiation and homeostasis upon brain invasion. Elegant experiments tracking microglia in the CNS allowed studies of their unique roles compared with other types of resident macrophages. Here we review the emerging roles of microglia in brain development, plasticity and cognition, and discuss the implications of the depletion or dysfunction of microglia for our understanding of disease pathogenesis. Immune activation, inflammation and various other conditions resulting in undesirable microglial activity at different stages of life could severely impair learning, memory and other essential cognitive functions. The diversity of microglial phenotypes across the lifespan, between compartments of the CNS, and sexes, as well as their crosstalk with the body and external environment, is also emphasised. Understanding what defines particular microglial phenotypes is of major importance for future development of innovative therapies controlling their effector functions, with consequences for cognition across chronic stress, ageing, neuropsychiatric and neurological diseases.
Collapse
Affiliation(s)
- Tuan Leng Tay
- Institute of Neuropathology, University of Freiburg, Germany
| | - Julie C Savage
- Axe Neurosciences, Centre de recherche du CHU de Québec, Québec, Canada
| | - Chin Wai Hui
- Axe Neurosciences, Centre de recherche du CHU de Québec, Québec, Canada
| | - Kanchan Bisht
- Axe Neurosciences, Centre de recherche du CHU de Québec, Québec, Canada
| | | |
Collapse
|
175
|
Abiega O, Beccari S, Diaz-Aparicio I, Nadjar A, Layé S, Leyrolle Q, Gómez-Nicola D, Domercq M, Pérez-Samartín A, Sánchez-Zafra V, Paris I, Valero J, Savage JC, Hui CW, Tremblay MÈ, Deudero JJP, Brewster AL, Anderson AE, Zaldumbide L, Galbarriatu L, Marinas A, Vivanco MDM, Matute C, Maletic-Savatic M, Encinas JM, Sierra A. Neuronal Hyperactivity Disturbs ATP Microgradients, Impairs Microglial Motility, and Reduces Phagocytic Receptor Expression Triggering Apoptosis/Microglial Phagocytosis Uncoupling. PLoS Biol 2016; 14:e1002466. [PMID: 27228556 PMCID: PMC4881984 DOI: 10.1371/journal.pbio.1002466] [Citation(s) in RCA: 114] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 04/21/2016] [Indexed: 12/24/2022] Open
Abstract
Phagocytosis is essential to maintain tissue homeostasis in a large number of inflammatory and autoimmune diseases, but its role in the diseased brain is poorly explored. Recent findings suggest that in the adult hippocampal neurogenic niche, where the excess of newborn cells undergo apoptosis in physiological conditions, phagocytosis is efficiently executed by surveillant, ramified microglia. To test whether microglia are efficient phagocytes in the diseased brain as well, we confronted them with a series of apoptotic challenges and discovered a generalized response. When challenged with excitotoxicity in vitro (via the glutamate agonist NMDA) or inflammation in vivo (via systemic administration of bacterial lipopolysaccharides or by omega 3 fatty acid deficient diets), microglia resorted to different strategies to boost their phagocytic efficiency and compensate for the increased number of apoptotic cells, thus maintaining phagocytosis and apoptosis tightly coupled. Unexpectedly, this coupling was chronically lost in a mouse model of mesial temporal lobe epilepsy (MTLE) as well as in hippocampal tissue resected from individuals with MTLE, a major neurological disorder characterized by seizures, excitotoxicity, and inflammation. Importantly, the loss of phagocytosis/apoptosis coupling correlated with the expression of microglial proinflammatory, epileptogenic cytokines, suggesting its contribution to the pathophysiology of epilepsy. The phagocytic blockade resulted from reduced microglial surveillance and apoptotic cell recognition receptor expression and was not directly mediated by signaling through microglial glutamate receptors. Instead, it was related to the disruption of local ATP microgradients caused by the hyperactivity of the hippocampal network, at least in the acute phase of epilepsy. Finally, the uncoupling led to an accumulation of apoptotic newborn cells in the neurogenic niche that was due not to decreased survival but to delayed cell clearance after seizures. These results demonstrate that the efficiency of microglial phagocytosis critically affects the dynamics of apoptosis and urge to routinely assess the microglial phagocytic efficiency in neurodegenerative disorders. Phagocytosis by microglia is tightly coupled to apoptosis, swiftly removing apoptotic cells and actively maintaining tissue homeostasis, but the neuronal hyperactivity associated with epilepsy disrupts the ATP gradients that drive phagocytosis, leading to the accumulation of apoptotic cells and inflammation. Phagocytosis, the engulfment and digestion of cellular debris, is at the core of the regenerative response of the damaged tissue, because it prevents the spillover of toxic intracellular contents and is actively anti-inflammatory. In the brain, the professional phagocytes are microglia, whose dynamic processes rapidly engulf and degrade cells undergoing apoptosis—programmed cell death—in physiological conditions. Thus, microglia hold the key to brain regeneration, but their efficiency as phagocytes in the diseased brain is only presumed. Here, we have discovered a generalized response of microglia to apoptotic challenge induced by excitotoxicity and inflammation, in which they boost their phagocytic efficiency to account for the increase in apoptosis. To our surprise, this apoptosis/microglial phagocytosis coupling was lost in the hippocampus from human and experimental mesial temporal lobe epilepsy (MTLE), a major neurodegenerative disorder characterized by excitotoxicity, inflammation, and seizures. This uncoupling was due to widespread ATP release during neuronal hyperactivity, which “blinded” microglia to the ATP microgradients released by apoptotic cells as “find-me” signals. The impairment of phagocytosis led to the accumulation of apoptotic cells and the build-up of a detrimental inflammatory reaction. Our data advocates for systematic assessment of the efficiency of microglial phagocytosis in brain disorders.
Collapse
Affiliation(s)
- Oihane Abiega
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Sol Beccari
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Irune Diaz-Aparicio
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | | | - Sophie Layé
- Université Bordeaux Segalen, Bordeaux, France
| | | | - Diego Gómez-Nicola
- Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom
| | - María Domercq
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Alberto Pérez-Samartín
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Víctor Sánchez-Zafra
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Iñaki Paris
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | - Jorge Valero
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
- Ikerbasque Foundation, Bilbao, Spain
| | - Julie C. Savage
- Centre de recherche du CHU de Québec, Axe Neurosciences, Québec, Canada
- Université Laval, Département de médecine moléculaire, Québec, Canada
| | - Chin-Wai Hui
- Centre de recherche du CHU de Québec, Axe Neurosciences, Québec, Canada
- Université Laval, Département de médecine moléculaire, Québec, Canada
| | - Marie-Ève Tremblay
- Centre de recherche du CHU de Québec, Axe Neurosciences, Québec, Canada
- Université Laval, Département de médecine moléculaire, Québec, Canada
| | - Juan J. P. Deudero
- Baylor College of Medicine, The Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, United States of America
| | - Amy L. Brewster
- Baylor College of Medicine, The Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, United States of America
| | - Anne E. Anderson
- Baylor College of Medicine, The Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, United States of America
| | | | | | | | | | - Carlos Matute
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
| | | | - Juan M. Encinas
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
- Baylor College of Medicine, The Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, United States of America
| | - Amanda Sierra
- Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, Zamudio, Spain
- University of the Basque Country, Leioa, Spain
- Baylor College of Medicine, The Jan and Dan Duncan Neurological Research Institute at Texas Children’s Hospital, Houston, Texas, United States of America
- * E-mail:
| |
Collapse
|
176
|
Wu Y, Dissing-Olesen L, MacVicar BA, Stevens B. Microglia: Dynamic Mediators of Synapse Development and Plasticity. Trends Immunol 2016; 36:605-613. [PMID: 26431938 DOI: 10.1016/j.it.2015.08.008] [Citation(s) in RCA: 471] [Impact Index Per Article: 58.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 08/13/2015] [Accepted: 08/13/2015] [Indexed: 12/25/2022]
Abstract
Neuronal communication underlies all brain activity and the genesis of complex behavior. Emerging research has revealed an unexpected role for immune molecules in the development and plasticity of neuronal synapses. Moreover microglia, the resident immune cells of the brain, express and secrete immune-related signaling molecules that alter synaptic transmission and plasticity in the absence of inflammation. When inflammation does occur, microglia modify synaptic connections and synaptic plasticity required for learning and memory. Here we review recent findings demonstrating how the dynamic interactions between neurons and microglia shape the circuitry of the nervous system in the healthy brain and how altered neuron-microglia signaling could contribute to disease.
Collapse
Affiliation(s)
- Yuwen Wu
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02215, USA; These authors contributed equally to this work
| | - Lasse Dissing-Olesen
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T 2B5, Canada; These authors contributed equally to this work
| | - Brian A MacVicar
- Djavad Mowafaghian Centre for Brain Health, University of British Columbia, Vancouver, BC V6T 2B5, Canada
| | - Beth Stevens
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02215, USA.
| |
Collapse
|
177
|
Sipe GO, Lowery RL, Tremblay MÈ, Kelly EA, Lamantia CE, Majewska AK. Microglial P2Y12 is necessary for synaptic plasticity in mouse visual cortex. Nat Commun 2016; 7:10905. [PMID: 26948129 PMCID: PMC4786684 DOI: 10.1038/ncomms10905] [Citation(s) in RCA: 338] [Impact Index Per Article: 42.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 02/01/2016] [Indexed: 12/19/2022] Open
Abstract
Microglia are the resident immune cells of the brain. Increasingly, they are recognized as important mediators of normal neurophysiology, particularly during early development. Here we demonstrate that microglia are critical for ocular dominance plasticity. During the visual critical period, closure of one eye elicits changes in the structure and function of connections underlying binocular responses of neurons in the visual cortex. We find that microglia respond to monocular deprivation during the critical period, altering their morphology, motility and phagocytic behaviour as well as interactions with synapses. To explore the underlying mechanism, we focused on the P2Y12 purinergic receptor, which is selectively expressed in non-activated microglia and mediates process motility during early injury responses. We find that disrupting this receptor alters the microglial response to monocular deprivation and abrogates ocular dominance plasticity. These results suggest that microglia actively contribute to experience-dependent plasticity in the adolescent brain. Microglia play key roles during early neurodevelopment. Here the authors show that microglia are important mediators of ocular dominance plasticity (ODP). Microglia respond to monocular deprivation during the visual critical period, and disrupting microglial P2Y12 purinergic receptor abrogates ODP.
Collapse
Affiliation(s)
- G O Sipe
- Department of Neuroscience, University of Rochester, 601 Elmwood Avenue, box 603, Rochester, New York 14642, USA.,Neuroscience Graduate Program, University of Rochester, 601 Elmwood Avenue, box 603, Rochester, New York 14642, USA
| | - R L Lowery
- Department of Neuroscience, University of Rochester, 601 Elmwood Avenue, box 603, Rochester, New York 14642, USA.,Neuroscience Graduate Program, University of Rochester, 601 Elmwood Avenue, box 603, Rochester, New York 14642, USA
| | - M-È Tremblay
- Department of Neuroscience, University of Rochester, 601 Elmwood Avenue, box 603, Rochester, New York 14642, USA
| | - E A Kelly
- Department of Neuroscience, University of Rochester, 601 Elmwood Avenue, box 603, Rochester, New York 14642, USA
| | - C E Lamantia
- Department of Neuroscience, University of Rochester, 601 Elmwood Avenue, box 603, Rochester, New York 14642, USA
| | - A K Majewska
- Department of Neuroscience, University of Rochester, 601 Elmwood Avenue, box 603, Rochester, New York 14642, USA.,Neuroscience Graduate Program, University of Rochester, 601 Elmwood Avenue, box 603, Rochester, New York 14642, USA
| |
Collapse
|
178
|
Glial cell response after aneurysmal subarachnoid hemorrhage — Functional consequences and clinical implications. Biochim Biophys Acta Mol Basis Dis 2016; 1862:492-505. [DOI: 10.1016/j.bbadis.2015.10.013] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/12/2015] [Accepted: 10/15/2015] [Indexed: 12/17/2022]
|
179
|
Resende FFB, Bai X, Del Bel EA, Kirchhoff F, Scheller A, Titze-de-Almeida R. Evaluation of TgH(CX3CR1-EGFP) mice implanted with mCherry-GL261 cells as an in vivo model for morphometrical analysis of glioma-microglia interaction. BMC Cancer 2016; 16:72. [PMID: 26856327 PMCID: PMC4746826 DOI: 10.1186/s12885-016-2118-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 02/03/2016] [Indexed: 11/21/2022] Open
Abstract
Background Glioblastoma multiforme is the most aggressive brain tumor. Microglia are prominent cells within glioma tissue and play important roles in tumor biology. This work presents an animal model designed for the study of microglial cell morphology in situ during gliomagenesis. It also allows a quantitative morphometrical analysis of microglial cells during their activation by glioma cells. Methods The animal model associates the following cell types: 1- mCherry red fluorescent GL261 glioma cells and; 2- EGFP fluorescent microglia, present in the TgH(CX3CR1-EGFP) mouse line. First, mCherry-GL261 glioma cells were implanted in the brain cortex of TgH(CX3CR1-EGFP) mice. Epifluorescence − and confocal laser-scanning microscopy were employed for analysis of fixed tissue sections, whereas two-photon laser-scanning microscopy (2P-LSM) was used to track tumor cells and microglia in the brain of living animals. Results Implanted mCherry-GL261 cells successfully developed brain tumors. They mimic the aggressive behavior found in human disease, with a rapid increase in size and the presence of secondary tumors apart from the injection site. As tumor grows, mCherry-GL261 cells progressively lost their original shape, adopting a heterogeneous and diffuse morphology at 14–18 d. Soma size increased from 10–52 μm. At this point, we focused on the kinetics of microglial access to glioma tissues. 2P-LSM revealed an intense microgliosis in brain areas already shortly after tumor implantation, i.e. at 30 min. By confocal microscopy, we found clusters of microglial cells around the tumor mass in the first 3 days. Then cells infiltrated the tumor area, where they remained during all the time points studied, from 6–18 days. Microglia in contact with glioma cells also present changes in cell morphology, from a ramified to an amoeboid shape. Cell bodies enlarged from 366 ± 0.0 μm2, in quiescent microglia, to 1310 ± 146.0 μm2, and the cell processes became shortened. Conclusions The GL261/CX3CR1 mouse model reported here is a valuable tool for imaging of microglial cells during glioma growth, either in fixed tissue sections or living animals. Remarkable advantages are the use of immunocompetent animals and the simplified imaging method without the need of immunohistochemical procedures.
Collapse
Affiliation(s)
- Fernando F B Resende
- Laboratório de Tecnologias para Terapia Gênica, ASS 128, ICC Sul, Universidade de Brasília-UnB, Campus Darcy Ribeiro, FAV., Brasília, DF, Brasil, 70910-970. .,Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany.
| | - Xianshu Bai
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany.
| | - Elaine Aparecida Del Bel
- Laboratório de Neurofisiologia e Biologia Molecular, Department Morfologia Fisiologia e Patologia Básica, FORP, Universidade de São Paulo - USP, Ribeirão Preto, SP, Brasil, 14040-904.
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany.
| | - Anja Scheller
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany.
| | - Ricardo Titze-de-Almeida
- Laboratório de Tecnologias para Terapia Gênica, ASS 128, ICC Sul, Universidade de Brasília-UnB, Campus Darcy Ribeiro, FAV., Brasília, DF, Brasil, 70910-970.
| |
Collapse
|
180
|
Rial D, Lemos C, Pinheiro H, Duarte JM, Gonçalves FQ, Real JI, Prediger RD, Gonçalves N, Gomes CA, Canas PM, Agostinho P, Cunha RA. Depression as a Glial-Based Synaptic Dysfunction. Front Cell Neurosci 2016; 9:521. [PMID: 26834566 PMCID: PMC4722129 DOI: 10.3389/fncel.2015.00521] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 12/27/2015] [Indexed: 01/23/2023] Open
Abstract
Recent studies combining pharmacological, behavioral, electrophysiological and molecular approaches indicate that depression results from maladaptive neuroplastic processes occurring in defined frontolimbic circuits responsible for emotional processing such as the prefrontal cortex, hippocampus, amygdala and ventral striatum. However, the exact mechanisms controlling synaptic plasticity that are disrupted to trigger depressive conditions have not been elucidated. Since glial cells (astrocytes and microglia) tightly and dynamically interact with synapses, engaging a bi-directional communication critical for the processing of synaptic information, we now revisit the role of glial cells in the etiology of depression focusing on a dysfunction of the “quad-partite” synapse. This interest is supported by the observations that depressive-like conditions are associated with a decreased density and hypofunction of astrocytes and with an increased microglia “activation” in frontolimbic regions, which is expected to contribute for the synaptic dysfunction present in depression. Furthermore, the traditional culprits of depression (glucocorticoids, biogenic amines, brain-derived neurotrophic factor, BDNF) affect glia functioning, whereas antidepressant treatments (serotonin-selective reuptake inhibitors, SSRIs, electroshocks, deep brain stimulation) recover glia functioning. In this context of a quad-partite synapse, systems modulating glia-synapse bidirectional communication—such as the purinergic neuromodulation system operated by adenosine 5′-triphosphate (ATP) and adenosine—emerge as promising candidates to “re-normalize” synaptic function by combining direct synaptic effects with an ability to also control astrocyte and microglia function. This proposed triple action of purines to control aberrant synaptic function illustrates the rationale to consider the interference with glia dysfunction as a mechanism of action driving the design of future pharmacological tools to manage depression.
Collapse
Affiliation(s)
- Daniel Rial
- CNC - Center for Neuroscience and Cell Biology, University of CoimbraCoimbra, Portugal; Departamento de Farmacologia, Universidade Federal de Santa Catarina, Florianópolis, SCBrazil
| | - Cristina Lemos
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Helena Pinheiro
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Joana M Duarte
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Francisco Q Gonçalves
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Joana I Real
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Rui D Prediger
- Departamento de Farmacologia, Universidade Federal de Santa Catarina, Florianópolis, SC Brazil
| | - Nélio Gonçalves
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Catarina A Gomes
- CNC - Center for Neuroscience and Cell Biology, University of CoimbraCoimbra, Portugal; Faculty of Medicine, University of CoimbraCoimbra, Portugal
| | - Paula M Canas
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal
| | - Paula Agostinho
- CNC - Center for Neuroscience and Cell Biology, University of CoimbraCoimbra, Portugal; Faculty of Medicine, University of CoimbraCoimbra, Portugal
| | - Rodrigo A Cunha
- CNC - Center for Neuroscience and Cell Biology, University of CoimbraCoimbra, Portugal; Faculty of Medicine, University of CoimbraCoimbra, Portugal
| |
Collapse
|
181
|
Hristovska I, Pascual O. Deciphering Resting Microglial Morphology and Process Motility from a Synaptic Prospect. Front Integr Neurosci 2016; 9:73. [PMID: 26834588 PMCID: PMC4717304 DOI: 10.3389/fnint.2015.00073] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 12/21/2015] [Indexed: 12/31/2022] Open
Abstract
Microglia, the resident immune cells of the central nervous system (CNS), were traditionally believed to be set into action only in case of injury or disease. Accordingly, microglia were assumed to be inactive or resting in the healthy brain. However, recent studies revealed that microglia carry out active tissue sampling in the intact brain by extending and retracting their ramified processes while periodically contacting synapses. Microglial morphology and motility as well as the frequency and duration of physical contacts with synaptic elements were found to be modulated by neuronal activity, sensory experience and neurotransmission; however findings have not been straightforward. Microglial cells are the most morphologically plastic element of the CNS. This unique feature confers them the possibility to locally sense activity, and to respond adequately by establishing synaptic contacts to regulate synaptic inputs by the secretion of signaling molecules. Indeed, microglial cells can hold new roles as critical players in maintaining brain homeostasis and regulating synaptic number, maturation and plasticity. For this reason, a better characterization of microglial cells and cues mediating neuron-to-microglia communication under physiological conditions may help advance our understanding of the microglial behavior and its regulation in the healthy brain. This review highlights recent findings on the instructive role of neuronal activity on microglial motility and microglia-synapse interactions, focusing on the main transmitters involved in this communication and including newly described communication at the tripartite synapse.
Collapse
Affiliation(s)
- Ines Hristovska
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research CenterLyon, France; Université Claude Bernard Lyon 1Lyon, France
| | - Olivier Pascual
- INSERM U1028, CNRS UMR5292, Lyon Neuroscience Research CenterLyon, France; Université Claude Bernard Lyon 1Lyon, France
| |
Collapse
|
182
|
Wang LC, Wu CL, Cheng YY, Tsai KJ. Deletion of Nuclear Localizing Signal Attenuates Proinflammatory Activity of Prothymosin-Alpha and Enhances Its Neuroprotective Effect on Transient Ischemic Stroke. Mol Neurobiol 2016; 54:582-593. [PMID: 26746667 DOI: 10.1007/s12035-015-9671-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 12/17/2015] [Indexed: 12/11/2022]
Abstract
Post-ischemic inflammation plays an important role in the progression of ischemia/reperfusion injuries. Prothymosin-α (ProT) can protect cells from necrotic death following ischemia; however, its immunostimulatory actions may counteract the neuroprotective effect. We proposed that ProTΔNLS, synthesized by deleting its nuclear localizing signal (NLS) at the C-terminal of ProT, can attenuate the immunostimulatory activity and has more salient neuroprotective effect. In this study, we examined the therapeutic effects of ProT and ProTΔNLS in a transient middle cerebral artery occlusion (tMCAO) model of rats. Rats that had sustained 90 min of tMCAO were treated with GST-vehicle, ProT, or ProTΔNLS. Therapeutic outcomes were evaluated by infarction volume assay and behavioral assessment. Changes to inflammatory mediators, including tumor necrosis factor α (TNF-α), interleukin-10 (IL-10), and myeloperoxidase (MPO) were evaluated by enzyme-linked immunosorbent assay. Activated matrix metalloproteinases 2 (MMP-2) and 9 (MMP-9) levels were evaluated by gelatin zymography. Microglial activation was identified by double-immunostaining for Iba-1 and CD68. Our results showed that while both ProT and ProTΔNLS reduce infarction volume and improve functional outcome, ProTΔNLS provides the best therapeutic outcome. ProT increases TNF-α but decreases IL-10 secretion after ischemic injury, reflecting its pro-inflammatory activity. ProTΔNLS suppresses expression of TNF-α, MPO, and activity of MMPs in ischemic brain tissue. It also suppresses activation of microglia in penumbral cortex. These data demonstrate the immunesuppressive activities of ProTΔNLS. In conclusion, ProT has pro-inflammatory effect that may counteract its neuroprotective effect. Deletion of NLS from ProT may attenuate post-ischemic inflammation and enhance the neuroprotective effects of ProT.
Collapse
Affiliation(s)
- Liang-Chao Wang
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Division of Neurosurgery, Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chao-Liang Wu
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Ya-Yun Cheng
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Kuen-Jer Tsai
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan. .,Center of Clinical Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
| |
Collapse
|
183
|
Avignone E, Lepleux M, Angibaud J, Nägerl UV. Altered morphological dynamics of activated microglia after induction of status epilepticus. J Neuroinflammation 2015; 12:202. [PMID: 26538404 PMCID: PMC4634193 DOI: 10.1186/s12974-015-0421-6] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 10/26/2015] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Microglia cells are the resident macrophages of the central nervous system and are considered its first line of defense. In the normal brain, their ramified processes are highly motile, constantly scanning the surrounding brain tissue and rapidly moving towards sites of acute injury or danger signals. These microglial dynamics are thought to be critical for brain homeostasis. Under pathological conditions, microglial cells undergo "activation," which modifies many of their molecular and morphological properties. Investigations of the effects of activation on motility are limited and have given mixed results. In particular, little is known about how microglial motility is altered in epilepsy, which is characterized by a strong inflammatory reaction and microglial activation. METHODS We used a mouse model of status epilepticus induced by kainate injections and time-lapse two-photon microscopy to image GFP-labeled microglia in acute hippocampal brain slices. We studied how microglial activation affected the motility of microglial processes, including basal motility, and their responses to local triggering stimuli. RESULTS Our study reveals that microglial motility was largely preserved in kainate-treated animals, despite clear signs of microglial activation. In addition, whereas the velocities of microglial processes during basal scanning and towards a laser lesion were unaltered 48 h after status epilepticus, we observed an increase in the size of the territory scanned by single microglial processes during basal motility and an elevated directional velocity towards a pipette containing a purinergic agonist. CONCLUSIONS Microglial activation differentially impacted the dynamic scanning behavior of microglia in response to specific acute noxious stimuli, which may be an important feature of the adaptive behavior of microglia during pathophysiological conditions.
Collapse
Affiliation(s)
- Elena Avignone
- Interdisciplinary Institute for Neurosciences, CNRS UMR 5297, 33077, Bordeaux, France. .,Université de Bordeaux, CNRS UMR 5297, 33077, Bordeaux, France.
| | - Marilyn Lepleux
- Interdisciplinary Institute for Neurosciences, CNRS UMR 5297, 33077, Bordeaux, France.,Université de Bordeaux, CNRS UMR 5297, 33077, Bordeaux, France
| | - Julie Angibaud
- Interdisciplinary Institute for Neurosciences, CNRS UMR 5297, 33077, Bordeaux, France.,Université de Bordeaux, CNRS UMR 5297, 33077, Bordeaux, France
| | - U Valentin Nägerl
- Interdisciplinary Institute for Neurosciences, CNRS UMR 5297, 33077, Bordeaux, France. .,Université de Bordeaux, CNRS UMR 5297, 33077, Bordeaux, France.
| |
Collapse
|
184
|
Liu J, Huang D, Xu J, Tong J, Wang Z, Huang L, Yang Y, Bai X, Wang P, Suo H, Ma Y, Yu M, Fei J, Huang F. Tiagabine Protects Dopaminergic Neurons against Neurotoxins by Inhibiting Microglial Activation. Sci Rep 2015; 5:15720. [PMID: 26499517 PMCID: PMC4620555 DOI: 10.1038/srep15720] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 10/02/2015] [Indexed: 01/04/2023] Open
Abstract
Microglial activation and inflammation are associated with progressive neuronal apoptosis in neurodegenerative disorders such as Parkinson's disease (PD). γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system, has recently been shown to play an inhibitory role in the immune system. Tiagabine, a piperidine derivative, enhances GABAergic transmission by inhibiting GABA transporter 1 (GAT 1). In the present study, we found that tiagabine pretreatment attenuated microglial activation, provided partial protection to the nigrostriatal axis and improved motor deficits in a methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. The protective function of tiagabine was abolished in GAT 1 knockout mice that were challenged with MPTP. In an alternative PD model, induced by intranigral infusion of lipopolysaccharide (LPS), microglial suppression and subsequent neuroprotective effects of tiagabine were demonstrated. Furthermore, the LPS-induced inflammatory activation of BV-2 microglial cells and the toxicity of conditioned medium toward SH-SY5Y cells were inhibited by pretreatment with GABAergic drugs. The attenuation of the nuclear translocation of nuclear factor κB (NF-κB) and the inhibition of the generation of inflammatory mediators were the underlying mechanisms. Our results suggest that tiagabine acts as a brake for nigrostriatal microglial activation and that it might be a novel therapeutic approach for PD.
Collapse
Affiliation(s)
- Jie Liu
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.,Research Center for Translational Medicine and Institute of Heart Failure, East Hospital, Tongji University, Shanghai 200120, China
| | - Dongping Huang
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Jing Xu
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Jiabin Tong
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Zishan Wang
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Li Huang
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Yufang Yang
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Xiaochen Bai
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Pan Wang
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Haiyun Suo
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Yuanyuan Ma
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Mei Yu
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China
| | - Jian Fei
- School of Life Science and Technology, Tongji University, 1239 Siping Road, Shanghai 200092, China.,Shanghai Research Center for Model Organisms, Pudong, Shanghai 201203, China
| | - Fang Huang
- The State Key Laboratory of Medical Neurobiology, the Institutes of Brain Science and the Collaborative Innovation Center for Brain Science, Shanghai Medical College, Fudan University, 138 Yixueyuan Road, Shanghai 200032, China.,Key Laboratory of Smart Drug Delivery, Fudan University, Ministry of Education, Shanghai 201203, China
| |
Collapse
|
185
|
Vasconcelos BCB, Vieira JA, Silva GO, Fernandes TN, Rocha LC, Viana AP, Serique CDS, Filho CS, Bringel RAR, Teixeira FFDL, Ferreira MS, Casseb SMM, Carvalho VL, de Melo KFL, de Castro PHG, Araújo SC, Diniz JAP, Demachki S, Anaissi AKM, Sosthenes MCK, Vasconcelos PFDC, Anthony DC, Diniz CWP, Diniz DG. Antibody-enhanced dengue disease generates a marked CNS inflammatory response in the black-tufted marmoset Callithrix penicillata. Neuropathology 2015; 36:3-16. [PMID: 26303046 DOI: 10.1111/neup.12229] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 06/01/2015] [Indexed: 10/23/2022]
Abstract
Severe dengue disease is often associated with long-term neurological impairments, but it is unclear what mechanisms are associated with neurological sequelae. Previously, we demonstrated antibody-enhanced dengue disease (ADE) dengue in an immunocompetent mouse model with a dengue virus 2 (DENV2) antibody injection followed by DENV3 virus infection. Here we migrated this ADE model to Callithrix penicillata. To mimic human multiple infections of endemic zones where abundant vectors and multiple serotypes co-exist, three animals received weekly subcutaneous injections of DENV3 (genotype III)-infected supernatant of C6/36 cell cultures, followed 24 h later by anti-DENV2 antibody for 12 weeks. There were six control animals, two of which received weekly anti-DENV2 antibodies, and four further animals received no injections. After multiple infections, brain, liver, and spleen samples were collected and tissue was immunolabeled for DENV3 antigens, ionized calcium binding adapter molecule 1, Ki-67, TNFα. There were marked morphological changes in the microglial population of ADE monkeys characterized by more highly ramified microglial processes, higher numbers of trees and larger surface areas. These changes were associated with intense TNFα-positive immunolabeling. It is unclear why ADE should generate such microglial activation given that IgG does not cross the blood-brain barrier, but this study reveals that in ADE dengue therapy targeting the CNS host response is likely to be important.
Collapse
Affiliation(s)
| | - Juliana Almeida Vieira
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| | - Geane Oliveira Silva
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| | | | - Luciano Chaves Rocha
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| | - André Pereira Viana
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| | - Cássio Diego Sá Serique
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| | - Carlos Santos Filho
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| | - Raissa Aires Ribeiro Bringel
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| | - Francisco Fernando Dacier Lobato Teixeira
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| | | | | | | | | | | | | | | | - Samia Demachki
- Universidade Federal do Pará, UFPA, Instituto de Ciências da Saúde, Laboratório de Anatomia Patológica, Hospital Universitário João de Barros Barreto, Belém, Pará, Brasil
| | - Ana Karyssa Mendes Anaissi
- Universidade Federal do Pará, UFPA, Instituto de Ciências da Saúde, Laboratório de Anatomia Patológica, Hospital Universitário João de Barros Barreto, Belém, Pará, Brasil
| | - Marcia Consentino Kronka Sosthenes
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| | | | - Daniel Clive Anthony
- Department of Pharmacology, Laboratory of Experimental Neuropathology, University of Oxford, Mansfield Road, Oxford, United Kingdom
| | - Cristovam Wanderley Picanço Diniz
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| | - Daniel Guerreiro Diniz
- Universidade Federal do Pará, UFPA, Instituto de Ciências Biológicas, Laboratório de Investigações em Neurodegeneração e Infecção, Hospital Universitário João de Barros Barreto
| |
Collapse
|
186
|
Wei R, Wang J, Xu Y, Yin B, He F, Du Y, Peng G, Luo B. Probenecid protects against cerebral ischemia/reperfusion injury by inhibiting lysosomal and inflammatory damage in rats. Neuroscience 2015; 301:168-77. [PMID: 26047730 DOI: 10.1016/j.neuroscience.2015.05.070] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 05/14/2015] [Accepted: 05/28/2015] [Indexed: 10/23/2022]
Abstract
Probenecid has been used for decades to treat gout, and recent studies have revealed it is also a specific inhibitor of the pannexin-1 channel. It has been reported that the pannexin-1 channel is involved in ischemic injury. Here, we investigated the neuroprotective effect and the possible mechanisms of action of probenecid in global cerebral ischemia/reperfusion (I/R) injury in rats. Twenty minutes of transient global cerebral I/R injury was induced using the four-vessel occlusion (4-VO) method in male Sprague-Dawley rats. Different doses of probenecid were administered intravenously, intraperitoneally, or by gavage before or after reperfusion. Probenecid via all three routes protected against CA1 neuronal death when given before reperfusion. This protective effect continued when probenecid was given at 2h after reperfusion, but not at 6h. Interestingly, the protective effect regained if probenecid was given continuously for 7days after reperfusion. The release of cathepsin B and overexpression of calpain-1 after reperfusion were inhibited, while the upregulation of Hsp70 was strengthened by probenecid pre-treatment. Furthermore, the activation and proliferation of microglia and astrocytes after I/R injury were suppressed by continuous given for 7days, but only partly by a single dose at 6h of reperfusion. Thus, our data indicate that probenecid protects against transient global cerebral I/R injury probably by inhibiting calpain-cathepsin pathway and the inflammatory reaction.
Collapse
Affiliation(s)
- R Wei
- The Brain Medical Center and the Collaborative Innovation Center for Brain Science, Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - J Wang
- Department of Neurology, The First Affiliated Hospital, Anhui Medical University, Hefei 230022, China
| | - Y Xu
- The Brain Medical Center and the Collaborative Innovation Center for Brain Science, Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - B Yin
- Department of Neurology, Renmin Hospital, Wuhan University, Wuhan 430000, China
| | - F He
- The Brain Medical Center and the Collaborative Innovation Center for Brain Science, Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - Y Du
- The Brain Medical Center and the Collaborative Innovation Center for Brain Science, Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - G Peng
- The Brain Medical Center and the Collaborative Innovation Center for Brain Science, Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China
| | - B Luo
- The Brain Medical Center and the Collaborative Innovation Center for Brain Science, Department of Neurology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou 310003, China.
| |
Collapse
|
187
|
Decrock E, De Bock M, Wang N, Bultynck G, Giaume C, Naus CC, Green CR, Leybaert L. Connexin and pannexin signaling pathways, an architectural blueprint for CNS physiology and pathology? Cell Mol Life Sci 2015; 72:2823-51. [PMID: 26118660 PMCID: PMC11113968 DOI: 10.1007/s00018-015-1962-7] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/11/2015] [Indexed: 02/06/2023]
Abstract
The central nervous system (CNS) is composed of a highly heterogeneous population of cells. Dynamic interactions between different compartments (neuronal, glial, and vascular systems) drive CNS function and allow to integrate and process information as well as to respond accordingly. Communication within this functional unit, coined the neuro-glio-vascular unit (NGVU), typically relies on two main mechanisms: direct cell-cell coupling via gap junction channels (GJCs) and paracrine communication via the extracellular compartment, two routes to which channels composed of transmembrane connexin (Cx) or pannexin (Panx) proteins can contribute. Multiple isoforms of both protein families are present in the CNS and each CNS cell type is characterized by a unique Cx/Panx portfolio. Over the last two decades, research has uncovered a multilevel platform via which Cxs and Panxs can influence different cellular functions within a tissue: (1) Cx GJCs enable a direct cell-cell communication of small molecules, (2) Cx hemichannels and Panx channels can contribute to autocrine/paracrine signaling pathways, and (3) different structural domains of these proteins allow for channel-independent functions, such as cell-cell adhesion, interactions with the cytoskeleton, and the activation of intracellular signaling pathways. In this paper, we discuss current knowledge on their multifaceted contribution to brain development and to specific processes in the NGVU, including synaptic transmission and plasticity, glial signaling, vasomotor control, and blood-brain barrier integrity in the mature CNS. By highlighting both physiological and pathological conditions, it becomes evident that Cxs and Panxs can play a dual role in the CNS and that an accurate fine-tuning of each signaling mechanism is crucial for normal CNS physiology.
Collapse
Affiliation(s)
- Elke Decrock
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Marijke De Bock
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Nan Wang
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signalling, Department of Cellular and Molecular Medicine, KU Leuven, Louvain, Belgium
| | - Christian Giaume
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, 75231 Paris Cedex 05, France
- University Pierre et Marie
Curie, ED, N°158, 75005 Paris, France
- MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005 Paris, France
| | - Christian C. Naus
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC V6T 1Z3 Canada
| | - Colin R. Green
- Department of Ophthalmology, The University of Auckland, Auckland, New Zealand
| | - Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Ghent University, De Pintelaan 185 (Block B, 3rd floor), 9000 Ghent, Belgium
| |
Collapse
|
188
|
de Sousa AA, Dos Reis RR, de Lima CM, de Oliveira MA, Fernandes TN, Gomes GF, Diniz DG, Magalhães NM, Diniz CG, Sosthenes MCK, Bento-Torres J, Diniz JAP, Vasconcelos PFDC, Diniz CWP. Three-dimensional morphometric analysis of microglial changes in a mouse model of virus encephalitis: age and environmental influences. Eur J Neurosci 2015; 42:2036-50. [PMID: 25980955 DOI: 10.1111/ejn.12951] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 04/16/2015] [Accepted: 05/13/2015] [Indexed: 02/05/2023]
Abstract
Many RNA virus CNS infections cause neurological disease. Because Piry virus has a limited human pathogenicity and exercise reduces activation of microglia in aged mice, possible influences of environment and aging on microglial morphology and behavior in mice sublethal encephalitis were investigated. Female albino Swiss mice were raised either in standard (S) or in enriched (EE) cages from age 2 to 6 months (young - Y), or from 2 to 16 months (aged - A). After behavioral tests, mice nostrils were instilled with Piry-virus-infected or with normal brain homogenates. Brain sections were immunolabeled for virus antigens or microglia at 8 days post-infection (dpi), when behavioral changes became apparent, and at 20 and 40 dpi, after additional behavioral testing. Young infected mice from standard (SYPy) and enriched (EYPy) groups showed similar transient impairment in burrowing activity and olfactory discrimination, whereas aged infected mice from both environments (EAPy, SAPy) showed permanent reduction in both tasks. The beneficial effects of an enriched environment were smaller in aged than in young mice. Six-hundred and forty microglial cells, 80 from each group were reconstructed. An unbiased, stereological sampling approach and multivariate statistical analysis were used to search for microglial morphological families. This procedure allowed distinguishing between microglial morphology of infected and control subjects. More severe virus-associated microglial changes were observed in young than in aged mice, and EYPy seem to recover microglial homeostatic morphology earlier than SYPy . Because Piry-virus encephalitis outcomes were more severe in aged mice, it is suggested that the reduced inflammatory response in those individuals may aggravate encephalitis outcomes.
Collapse
Affiliation(s)
- Aline A de Sousa
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Laboratório de Investigações em Neurodegeneração e Infecção no Hospital Universitário João de Barros Barreto, Belém, Pará, Brazil
| | - Renata R Dos Reis
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Laboratório de Investigações em Neurodegeneração e Infecção no Hospital Universitário João de Barros Barreto, Belém, Pará, Brazil
| | - Camila M de Lima
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Laboratório de Investigações em Neurodegeneração e Infecção no Hospital Universitário João de Barros Barreto, Belém, Pará, Brazil
| | - Marcus A de Oliveira
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Laboratório de Investigações em Neurodegeneração e Infecção no Hospital Universitário João de Barros Barreto, Belém, Pará, Brazil
| | | | - Giovanni F Gomes
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Laboratório de Investigações em Neurodegeneração e Infecção no Hospital Universitário João de Barros Barreto, Belém, Pará, Brazil
| | - Daniel G Diniz
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Laboratório de Investigações em Neurodegeneração e Infecção no Hospital Universitário João de Barros Barreto, Belém, Pará, Brazil
| | - Nara M Magalhães
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Laboratório de Investigações em Neurodegeneração e Infecção no Hospital Universitário João de Barros Barreto, Belém, Pará, Brazil
| | - Cristovam G Diniz
- Instituto Federal de Educação, Ciência e Tecnologia do Pará, Bragança, Pará, Brazil
| | - Marcia C K Sosthenes
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Laboratório de Investigações em Neurodegeneração e Infecção no Hospital Universitário João de Barros Barreto, Belém, Pará, Brazil
| | - João Bento-Torres
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Laboratório de Investigações em Neurodegeneração e Infecção no Hospital Universitário João de Barros Barreto, Belém, Pará, Brazil
| | - José Antonio P Diniz
- Instituto Evandro Chagas (IEC), Departamento de Arbovirologia e Febres Hemorrágicas, Ananindeua, Pará, Brazil
| | - Pedro F da C Vasconcelos
- Instituto Evandro Chagas (IEC), Departamento de Arbovirologia e Febres Hemorrágicas, Ananindeua, Pará, Brazil
| | - Cristovam Wanderley P Diniz
- Instituto de Ciências Biológicas, Universidade Federal do Pará, Laboratório de Investigações em Neurodegeneração e Infecção no Hospital Universitário João de Barros Barreto, Belém, Pará, Brazil.,Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| |
Collapse
|
189
|
Mayhew J, Beart PM, Walker FR. Astrocyte and microglial control of glutamatergic signalling: a primer on understanding the disruptive role of chronic stress. J Neuroendocrinol 2015; 27:498-506. [PMID: 25737228 DOI: 10.1111/jne.12273] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Revised: 02/23/2015] [Accepted: 02/27/2015] [Indexed: 01/23/2023]
Abstract
It is now well established that chronic stress can induce significant structural remodelling of astrocytes and microglia. Until recently, however, the full significance of these morphological disturbances has remained unclear. Clues to the significance of astroglial re-organisation following stress are beginning to emerge from a compelling literature describing how astrocytes contribute to glutamatergic neurotransmission. The present review briefly summarises these two fields of research, identifies points of overlap and, in doing so, pin-points future research directions for stress neurobiology. Ultimately, understanding how chronic stress can disrupt the interactions of astrocytes and microglia with neurones has the potential in the future to improve the development of therapeutics designed to treat stress-related illnesses such as depression.
Collapse
Affiliation(s)
- J Mayhew
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
- Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan, NSW, Australia
- Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
| | - P M Beart
- Florey Institute of Neuroscience and Mental Health, The University of Melbourne, Parkville, Vic., Australia
| | - F R Walker
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
- Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan, NSW, Australia
- Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
| |
Collapse
|
190
|
Reichenbach A, Bringmann A. Purinergic signaling in retinal degeneration and regeneration. Neuropharmacology 2015; 104:194-211. [PMID: 25998275 DOI: 10.1016/j.neuropharm.2015.05.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 05/07/2015] [Accepted: 05/07/2015] [Indexed: 02/01/2023]
Abstract
Purinergic signaling is centrally involved in mediating the degeneration of the injured and diseased retina, the induction of retinal gliosis, and the protection of the retinal tissue from degeneration. Dysregulated calcium signaling triggered by overactivation of P2X7 receptors is a crucial step in the induction of neuronal and microvascular cell death under pathogenic conditions like ischemia-hypoxia, elevated intraocular pressure, and diabetes, respectively. Overactivation of P2X7 plays also a pathogenic role in inherited and age-related photoreceptor cell death and in the age-related dysfunction and degeneration of the retinal pigment epithelium. Gliosis of micro- and macroglial cells, which is induced and/or modulated by purinergic signaling and associated with an impaired homeostatic support to neurons, and the ATP-mediated propagation of retinal gliosis from a focal injury into the surrounding noninjured tissue are involved in inducing secondary cell death in the retina. On the other hand, alterations in the glial metabolism of extracellular nucleotides, resulting in a decreased level of ATP and an increased level of adenosine, may be neuroprotective in the diseased retina. Purinergic signals stimulate the proliferation of retinal glial cells which contributes to glial scarring which has protective effects on retinal degeneration and adverse effects on retinal regeneration. Pharmacological modulation of purinergic receptors, e.g., inhibition of P2X and activation of adenosine receptors, may have clinical importance for the prevention of photoreceptor, neuronal, and microvascular cell death in diabetic retinopathy, retinitis pigmentosa, age-related macular degeneration, and glaucoma, respectively, for the clearance of retinal edema, and the inhibition of dysregulated cell proliferation in proliferative retinopathies. This article is part of a Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
Collapse
Affiliation(s)
- Andreas Reichenbach
- Paul Flechsig Institute of Brain Research, University of Leipzig, Leipzig, Germany.
| | - Andreas Bringmann
- Department of Ophthalmology and Eye Hospital, University of Leipzig, Leipzig, Germany
| |
Collapse
|
191
|
Franklin TC, Wohleb ES, Duman RS. The Role of Immune Cells in the Brain during Physiological and Pathological Conditions. Psychiatr Ann 2015. [DOI: 10.3928/00485713-20150501-05] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
192
|
Modulation of microglial process convergence toward neuronal dendrites by extracellular calcium. J Neurosci 2015; 35:2417-22. [PMID: 25673836 DOI: 10.1523/jneurosci.3279-14.2015] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Extracellular calcium concentrations in the brain fluctuate during neuronal activities and may affect the behavior of brain cells. Microglia are highly dynamic immune cells of the brain. However, the effects of extracellular calcium concentrations on microglial dynamics have not been investigated. Here, we addressed this question in mouse brain slices and in vivo using two-photon microscopy. We serendipitously found that extracellular calcium reduction induced microglial processes to converge at distinct sites, a phenomenon we termed microglial process convergence (MPCs). Our studies revealed that MPCs target neuronal dendrites independent of neuronal action potential firing and is mediated by ATP release and microglial P2Y12 receptors. These results indicate that microglia monitor and interact with neurons during conditions of cerebral calcium reduction in the normal and diseased brain.
Collapse
|
193
|
Madry C, Attwell D. Receptors, ion channels, and signaling mechanisms underlying microglial dynamics. J Biol Chem 2015; 290:12443-50. [PMID: 25855789 DOI: 10.1074/jbc.r115.637157] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Microglia, the innate immune cells of the CNS, play a pivotal role in brain injury and disease. Microglia are extremely motile; their highly ramified processes constantly survey the brain parenchyma, and they respond promptly to brain damage with targeted process movement toward the injury site. Microglia play a key role in brain development and function by pruning synapses during development, phagocytosing apoptotic newborn neurons, and regulating neuronal activity by direct microglia-neuron or indirect microglia-astrocyte-neuron interactions, which all depend on their process motility. This review highlights recent discoveries about microglial dynamics, focusing on the receptors, ion channels, and signaling pathways involved.
Collapse
Affiliation(s)
- Christian Madry
- From the Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - David Attwell
- From the Department of Neuroscience, Physiology & Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| |
Collapse
|
194
|
|
195
|
Xavier AL, Lima FRS, Nedergaard M, Menezes JRL. Ontogeny of CX3CR1-EGFP expressing cells unveil microglia as an integral component of the postnatal subventricular zone. Front Cell Neurosci 2015; 9:37. [PMID: 25741237 PMCID: PMC4330885 DOI: 10.3389/fncel.2015.00037] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 01/21/2015] [Indexed: 01/29/2023] Open
Abstract
The full spectrum of cellular interactions within CNS neurogenic niches is still poorly understood. Only recently has the monocyte counterpart of the nervous system, the microglial cells, been described as an integral cellular component of neurogenic niches. The present study sought to characterize the microglia population in the early postnatal subventricular zone (SVZ), the major site of postnatal neurogenesis, as well as in its anterior extension, the rostral migratory stream (RMS), a pathway for neuroblasts during their transit toward the olfactory bulb (OB) layers. Here we show that microglia within the SVZ/RMS pathway are not revealed by phenotypic markers that characterize microglia in other regions. Analysis of the transgenic mice strain that has one locus of the constitutively expressed fractalkine CX3CR1 receptor replaced by the gene encoding the enhanced green fluorescent protein (EGFP) circumvented the antigenic plasticity of the microglia, thus allowing us to depict microglia within the SVZ/RMS pathway during early development. Notably, microglia within the early SVZ/RMS are not proliferative and display a protracted development, retaining a more immature morphology than their counterparts outside germinal layers. Furthermore, microglia contact and phagocyte radial glia cells (RG) processes, thereby playing a role on the astroglial transformation that putative stem cells within the SVZ niche undergo during the first postnatal days.
Collapse
Affiliation(s)
- Anna L Xavier
- Programa em Ciências Morfológicas, Programa de Diferenciação Celular, Laboratório de Neuroanatomia Celular, Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil ; Center for Translational Neuromedicine, University of Rochester Medical School Rochester, NY, USA
| | - Flavia R S Lima
- Laboratório de Morfogênese Celular, Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical School Rochester, NY, USA
| | - João R L Menezes
- Programa em Ciências Morfológicas, Programa de Diferenciação Celular, Laboratório de Neuroanatomia Celular, Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| |
Collapse
|
196
|
Baalman K, Marin MA, Ho TSY, Godoy M, Cherian L, Robertson C, Rasband MN. Axon initial segment-associated microglia. J Neurosci 2015; 35:2283-92. [PMID: 25653382 PMCID: PMC4315845 DOI: 10.1523/jneurosci.3751-14.2015] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/02/2014] [Accepted: 12/22/2014] [Indexed: 01/31/2023] Open
Abstract
Microglia are the brain's resident immune cells and function as the main defense against pathogens or injury. However, in the absence of disease, microglia have other functions in the normal brain. For example, previous studies showed that microglia contribute to circuit refinement and synaptic plasticity in the developing and adult brain, respectively. Thus, microglia actively participate in regulating neuronal excitability and function. Here, we report that in the cortex, but not other brain regions, a subset of microglia extend a single process that specifically associates and overlaps with the axon initial segment (AIS), the site where action potentials are generated. Similar associations were not observed with dendrites or distal axons. Microglia-AIS interactions appear early in development, persist throughout adulthood, and are conserved across species including mice, rats, and primates. However, these interactions are lost after microglial activation following brain injury, suggesting that such interactions may be part of healthy brain function. Loss of microglial CX3CR1 receptors, or the specialized extracellular matrix surrounding the AIS, did not disrupt the interaction. However, loss of AIS proteins by the neuron-specific deletion of the master AIS scaffold AnkyrinG disrupted microglia-AIS interactions. These results reveal a unique population of microglia that specifically interact with the AIS in the adult cortex.
Collapse
Affiliation(s)
| | | | | | | | - Leela Cherian
- Department of Neurosurgery, Baylor College of Medicine, Houston, Texas 77030
| | - Claudia Robertson
- Department of Neuroscience, Department of Neurosurgery, Baylor College of Medicine, Houston, Texas 77030
| | | |
Collapse
|
197
|
Delpech JC, Madore C, Nadjar A, Joffre C, Wohleb ES, Layé S. Microglia in neuronal plasticity: Influence of stress. Neuropharmacology 2015; 96:19-28. [PMID: 25582288 DOI: 10.1016/j.neuropharm.2014.12.034] [Citation(s) in RCA: 98] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/24/2014] [Accepted: 12/29/2014] [Indexed: 01/17/2023]
Abstract
The central nervous system (CNS) has previously been regarded as an immune-privileged site with the absence of immune cell responses but this dogma was not entirely true. Microglia are the brain innate immune cells and recent findings indicate that they participate both in CNS disease and infection as well as facilitate normal CNS function. Microglia are highly plastic and play integral roles in sculpting the structure of the CNS, refining neuronal circuitry and connectivity, and contribute actively to neuronal plasticity in the healthy brain. Interestingly, psychological stress can perturb the function of microglia in association with an impaired neuronal plasticity and the development of emotional behavior alterations. As a result it seemed important to describe in this review some findings indicating that the stress-induced microglia dysfunction may underlie neuroplasticity deficits associated to many mood disorders. This article is part of a Special Issue entitled 'Neuroimmunology and Synaptic Function'.
Collapse
Affiliation(s)
- Jean-Christophe Delpech
- Nutrition et Neurobiologie Intégrée, INRA 1286, 33077 Bordeaux Cedex, France; Nutrition et Neurobiologie Intégrée, University of Bordeaux, Bordeaux 33077, France
| | - Charlotte Madore
- Nutrition et Neurobiologie Intégrée, INRA 1286, 33077 Bordeaux Cedex, France; Nutrition et Neurobiologie Intégrée, University of Bordeaux, Bordeaux 33077, France
| | - Agnes Nadjar
- Nutrition et Neurobiologie Intégrée, INRA 1286, 33077 Bordeaux Cedex, France; Nutrition et Neurobiologie Intégrée, University of Bordeaux, Bordeaux 33077, France
| | - Corinne Joffre
- Nutrition et Neurobiologie Intégrée, INRA 1286, 33077 Bordeaux Cedex, France; Nutrition et Neurobiologie Intégrée, University of Bordeaux, Bordeaux 33077, France
| | - Eric S Wohleb
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT 06519, USA
| | - Sophie Layé
- Nutrition et Neurobiologie Intégrée, INRA 1286, 33077 Bordeaux Cedex, France; Nutrition et Neurobiologie Intégrée, University of Bordeaux, Bordeaux 33077, France.
| |
Collapse
|
198
|
Karlstetter M, Scholz R, Rutar M, Wong WT, Provis JM, Langmann T. Retinal microglia: just bystander or target for therapy? Prog Retin Eye Res 2014; 45:30-57. [PMID: 25476242 DOI: 10.1016/j.preteyeres.2014.11.004] [Citation(s) in RCA: 372] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 11/20/2014] [Accepted: 11/25/2014] [Indexed: 10/24/2022]
Abstract
Resident microglial cells can be regarded as the immunological watchdogs of the brain and the retina. They are active sensors of their neuronal microenvironment and rapidly respond to various insults with a morphological and functional transformation into reactive phagocytes. There is strong evidence from animal models and in situ analyses of human tissue that microglial reactivity is a common hallmark of various retinal degenerative and inflammatory diseases. These include rare hereditary retinopathies such as retinitis pigmentosa and X-linked juvenile retinoschisis but also comprise more common multifactorial retinal diseases such as age-related macular degeneration, diabetic retinopathy, glaucoma, and uveitis as well as neurological disorders with ocular manifestation. In this review, we describe how microglial function is kept in balance under normal conditions by cross-talk with other retinal cells and summarize how microglia respond to different forms of retinal injury. In addition, we present the concept that microglia play a key role in local regulation of complement in the retina and specify aspects of microglial aging relevant for chronic inflammatory processes in the retina. We conclude that this resident immune cell of the retina cannot be simply regarded as bystander of disease but may instead be a potential therapeutic target to be modulated in the treatment of degenerative and inflammatory diseases of the retina.
Collapse
Affiliation(s)
- Marcus Karlstetter
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Rebecca Scholz
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany
| | - Matt Rutar
- The John Curtin School of Medical Research, The Australian National University (ANU), Canberra, Australian Capital Territory, Australia
| | - Wai T Wong
- Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Jan M Provis
- The John Curtin School of Medical Research, The Australian National University (ANU), Canberra, Australian Capital Territory, Australia
| | - Thomas Langmann
- Laboratory for Experimental Immunology of the Eye, Department of Ophthalmology, University of Cologne, Cologne, Germany.
| |
Collapse
|
199
|
Visuospatial learning and memory in the Cebus apella and microglial morphology in the molecular layer of the dentate gyrus and CA1 lacunosum molecular layer. J Chem Neuroanat 2014; 61-62:176-88. [PMID: 25462387 DOI: 10.1016/j.jchemneu.2014.10.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 09/18/2014] [Accepted: 10/13/2014] [Indexed: 11/23/2022]
Abstract
We investigated whether the morphology of microglia in the molecular layer of the dentate gyrus (DG-Mol) or in the lacunosum molecular layer of CA1 (CA1-LMol) was correlated with spatial learning and memory in the capuchin monkey (Cebus apella). Learning and memory was tested in 4 monkeys with visuo-spatial, paired associated learning (PAL) tasks from the Cambridge battery of neuropsychological tests. After testing, monkeys were sacrificed, and hippocampi were sectioned. We specifically immunolabeled microglia with an antibody against the adapter binding, ionized calcium protein. Microglia were selected from the middle and outer thirds of the DG-Mol (n=268) and the CA1-LMol (n=185) for three-dimensional reconstructions created with Neurolucida and Neuroexplorer software. Cluster and discriminant analyses, based on microglial morphometric parameters, identified two major morphological microglia phenotypes (types I and II) found in both the CA1-LMol and DG-Mol of all individuals. Compared to type II, type I microglia were significantly smaller, thinner, more tortuous and ramified, and less complex (lower fractal dimensions). PAL performance was both linearly and non-linearly correlated with type I microglial morphological features from the rostral and caudal DG-Mol, but not with microglia from the CA1-LMol. These differences in microglial morphology and correlations with PAL performance were consistent with previous proposals of hippocampal regional contributions for spatial learning and memory. Our results suggested that at least two morphological microglial phenotypes provided distinct physiological roles to learning-associated activity in the rostral and caudal DG-Mol of the monkey brain.
Collapse
|
200
|
Neuronal hyperactivity recruits microglial processes via neuronal NMDA receptors and microglial P2Y12 receptors after status epilepticus. J Neurosci 2014; 34:10528-40. [PMID: 25100587 DOI: 10.1523/jneurosci.0416-14.2014] [Citation(s) in RCA: 318] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Microglia are highly dynamic immune cells of the CNS and their dynamism is proposed to be regulated by neuronal activities. However, the mechanisms underlying neuronal regulation of microglial dynamism have not been determined. Here, we found an increased number of microglial primary processes in the hippocampus during KA-induced seizure activity. Consistently, global glutamate induced robust microglial process extension toward neurons in both brain slices and in the intact brain in vivo. The mechanism of the glutamate-induced microglial process extension involves the activation of neuronal NMDA receptors, calcium influx, subsequent ATP release, and microglial response through P2Y12 receptors. Seizure-induced increases in microglial process numbers were also dependent on NMDA receptor activation. Finally, we found that P2Y12 KO mice exhibited reduced seizure-induced increases in microglial process numbers and worsened KA-induced seizure behaviors. Our results elucidate the molecular mechanisms underlying microglia-neuron communication that may be potentially neuroprotective in the epileptic brain.
Collapse
|