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Belaya I, Ivanova M, Sorvari A, Ilicic M, Loppi S, Koivisto H, Varricchio A, Tikkanen H, Walker FR, Atalay M, Malm T, Grubman A, Tanila H, Kanninen KM. Astrocyte remodeling in the beneficial effects of long-term voluntary exercise in Alzheimer's disease. J Neuroinflammation 2020; 17:271. [PMID: 32933545 PMCID: PMC7493971 DOI: 10.1186/s12974-020-01935-w] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/19/2020] [Indexed: 12/22/2022] Open
Abstract
Background Increased physical exercise improves cognitive function and reduces pathology associated with Alzheimer’s disease (AD). However, the mechanisms underlying the beneficial effects of exercise in AD on the level of specific brain cell types remain poorly investigated. The involvement of astrocytes in AD pathology is widely described, but their exact role in exercise-mediated neuroprotection warrant further investigation. Here, we investigated the effect of long-term voluntary physical exercise on the modulation of the astrocyte state. Methods Male 5xFAD mice and their wild-type littermates had free access to a running wheel from 1.5 to 7 months of age. A battery of behavioral tests was used to assess the effects of voluntary exercise on cognition and learning. Neuronal loss, impairment in neurogenesis, beta-amyloid (Aβ) deposition, and inflammation were evaluated using a variety of histological and biochemical measurements. Sophisticated morphological analyses were performed to delineate the specific involvement of astrocytes in exercise-induced neuroprotection in the 5xFAD mice. Results Long-term voluntary physical exercise reversed cognitive impairment in 7-month-old 5xFAD mice without affecting neurogenesis, neuronal loss, Aβ plaque deposition, or microglia activation. Exercise increased glial fibrillary acid protein (GFAP) immunoreactivity and the number of GFAP-positive astrocytes in 5xFAD hippocampi. GFAP-positive astrocytes in hippocampi of the exercised 5xFAD mice displayed increases in the numbers of primary branches and in the soma area. In general, astrocytes distant from Aβ plaques were smaller in size and possessed simplified processes in comparison to plaque-associated GFAP-positive astrocytes. Morphological alterations of GFAP-positive astrocytes occurred concomitantly with increased astrocytic brain-derived neurotrophic factor (BDNF) and restoration of postsynaptic protein PSD-95. Conclusions Voluntary physical exercise modulates the reactive astrocyte state, which could be linked via astrocytic BDNF and PSD-95 to improved cognition in 5xFAD hippocampi. The molecular pathways involved in this modulation could potentially be targeted for benefit against AD.
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Affiliation(s)
- Irina Belaya
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FI-70211, Kuopio, Finland
| | - Mariia Ivanova
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FI-70211, Kuopio, Finland
| | - Annika Sorvari
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FI-70211, Kuopio, Finland
| | - Marina Ilicic
- School of Biomedical Sciences and Pharmacy and the Priority Research Centre for Stroke and Brain Injury, The University of Newcastle, University Dr, Callaghan, NSW, 2308, Australia
| | - Sanna Loppi
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FI-70211, Kuopio, Finland
| | - Hennariikka Koivisto
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FI-70211, Kuopio, Finland
| | - Alessandra Varricchio
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FI-70211, Kuopio, Finland
| | - Heikki Tikkanen
- Institute of Biomedicine, University of Eastern Finland, FI-70211, Kuopio, Finland
| | - Frederick R Walker
- School of Biomedical Sciences and Pharmacy and the Priority Research Centre for Stroke and Brain Injury, The University of Newcastle, University Dr, Callaghan, NSW, 2308, Australia
| | - Mustafa Atalay
- Institute of Biomedicine, University of Eastern Finland, FI-70211, Kuopio, Finland
| | - Tarja Malm
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FI-70211, Kuopio, Finland
| | - Alexandra Grubman
- Department of Anatomy and Developmental Biology, Monash University, Melbourne, Australia.,Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Melbourne, Australia.,Australian Regenerative Medicine Institute, Monash University, Melbourne, Australia
| | - Heikki Tanila
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FI-70211, Kuopio, Finland
| | - Katja M Kanninen
- A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, FI-70211, Kuopio, Finland.
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Abd-El-Basset EM, Rao MS, Alsaqobi A. Interferon-Gamma and Interleukin-1Beta Enhance the Secretion of Brain-Derived Neurotrophic Factor and Promotes the Survival of Cortical Neurons in Brain Injury. Neurosci Insights 2020; 15:2633105520947081. [PMID: 32776009 PMCID: PMC7391446 DOI: 10.1177/2633105520947081] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 07/14/2020] [Indexed: 12/28/2022] Open
Abstract
Neuro-inflammation is associated with the production of cytokines, which influence neuronal and glial functions. Although the proinflammatory cytokines interferon-γ (IFN-γ) and interleukin-1Beta (IL-1β) are thought to be the major mediators of neuro-inflammation, their role in brain injury remains ill-defined. The objective of this study was to examine the effect of IFN-γ and IL-1β on survival of cortical neurons in stab wound injury in mice. A stab wound injury was made in the cortex of male BALB/c mice. Injured mice (I) were divide into IFN-γ and IL-1β treatment experiments. Mice in I + IFN-γ group were treated with IFN-γ (ip, 10 µg/kg/day) for 1, 3 and 7 days and mice in I + IL-1β group were treated with 5 IP injection of IL-1β (0.5 µg /12 h). Appropriate control mice were maintained for comparison. Immunostaining of frozen brain sections for astrocytes (GFAP), microglia (Iba-1) and Fluoro-Jade B staining for degenerating neurons were used. Western blotting and ELISA for brain-derived neurotrophic factor (BDNF) were done on the tissues isolated from the injured sites. Results showed a significant increase in the number of both astrocytes and microglia in I + IFN-γ and I + IL-1β groups. There were no significant changes in the number of astrocytes or microglia in noninjury groups (NI) treated with IFN-γ or IL-1β. The number of degenerating neurons significantly decreased in I + IFN-γ and I + IL-1β groups. GFAP and BDNF levels were significantly increased in I + IFN-γ and I + IL-1β groups. Interferon-γ and IL-1β induce astrogliosis, microgliosis, enhance the secretion of BDNF, one of the many neurotrophic factors after brain injury, and promote the survival of cortical neurons in stab wound brain injury.
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Varas R, Ortiz FC. Neuroinflammation in Demyelinating Diseases: Oxidative Stress as a Modulator of Glial Cross-Talk. Curr Pharm Des 2020; 25:4755-4762. [PMID: 31840603 DOI: 10.2174/1381612825666191216125725] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 12/12/2019] [Indexed: 02/05/2023]
Abstract
Myelin is a specialized membrane allowing for saltatory conduction of action potentials in neurons, an essential process to achieve the normal communication across the nervous system. Accordingly, in diseases characterized by the loss of myelin and myelin forming cells -oligodendrocytes in the CNS-, patients show severe neurological disabilities. After a demyelinated insult, microglia, astrocytes and oligodendrocyte precursor cells invade the lesioned area initiating a spontaneous process of myelin repair (i.e. remyelination). A preserved hallmark of this neuroinflammatory scenario is a local increase of oxidative stress, where several cytokines and chemokines are released by glial and other cells. This generates an environment that determines cell interaction resulting in oligodendrocyte maturity and the ability to synthesize new myelin. Herein we review the main features of the regulatory aspect of these molecules based on recent findings and propose new putative signal molecules involved in the remyelination process, focused in the etiology of Multiple Sclerosis, one of the main demyelinating diseases causing disabilities in the population.
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Affiliation(s)
- Rodrigo Varas
- Mechanisms of Myelin Formation and Repair Laboratory, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Fernando C Ortiz
- Mechanisms of Myelin Formation and Repair Laboratory, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
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Ronzano R, Thetiot M, Lubetzki C, Desmazieres A. Myelin Plasticity and Repair: Neuro-Glial Choir Sets the Tuning. Front Cell Neurosci 2020; 14:42. [PMID: 32180708 PMCID: PMC7059744 DOI: 10.3389/fncel.2020.00042] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Accepted: 02/12/2020] [Indexed: 12/11/2022] Open
Abstract
The plasticity of the central nervous system (CNS) in response to neuronal activity has been suggested as early as 1894 by Cajal (1894). CNS plasticity has first been studied with a focus on neuronal structures. However, in the last decade, myelin plasticity has been unraveled as an adaptive mechanism of importance, in addition to the previously described processes of myelin repair. Indeed, it is now clear that myelin remodeling occurs along with life and adapts to the activity of neuronal networks. Until now, it has been considered as a two-part dialog between the neuron and the oligodendroglial lineage. However, other glial cell types might be at play in myelin plasticity. In the present review, we first summarize the key structural parameters for myelination, we then describe how neuronal activity modulates myelination and finally discuss how other glial cells could participate in myelinic adaptivity.
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Affiliation(s)
- Remi Ronzano
- Institut du Cerveau et de la Moelle épinière, Sorbonne Universités UPMC Université Paris 06, CNRS UMR7225-Inserm U1127, Paris, France
| | - Melina Thetiot
- Institut du Cerveau et de la Moelle épinière, Sorbonne Universités UPMC Université Paris 06, CNRS UMR7225-Inserm U1127, Paris, France
- Unit Zebrafish Neurogenetics, Department of Developmental & Stem Cell Biology, Institut Pasteur, CNRS, Paris, France
| | - Catherine Lubetzki
- Institut du Cerveau et de la Moelle épinière, Sorbonne Universités UPMC Université Paris 06, CNRS UMR7225-Inserm U1127, Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Pitié-Salpêtrière, Paris, France
| | - Anne Desmazieres
- Institut du Cerveau et de la Moelle épinière, Sorbonne Universités UPMC Université Paris 06, CNRS UMR7225-Inserm U1127, Paris, France
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Blocking the Thrombin Receptor Promotes Repair of Demyelinated Lesions in the Adult Brain. J Neurosci 2020; 40:1483-1500. [PMID: 31911460 DOI: 10.1523/jneurosci.2029-19.2019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 12/15/2019] [Accepted: 12/17/2019] [Indexed: 01/14/2023] Open
Abstract
Myelin loss limits neurological recovery and myelin regeneration and is critical for restoration of function. We recently discovered that global knock-out of the thrombin receptor, also known as Protease Activated Receptor 1 (PAR1), accelerates myelin development. Here we demonstrate that knocking out PAR1 also promotes myelin regeneration. Outcomes in two unique models of myelin injury and repair, that is lysolecithin or cuprizone-mediated demyelination, showed that PAR1 knock-out in male mice improves replenishment of myelinating cells and remyelinated nerve fibers and slows early axon damage. Improvements in myelin regeneration in PAR1 knock-out mice occurred in tandem with a skewing of reactive astrocyte signatures toward a prorepair phenotype. In cell culture, the promyelinating effects of PAR1 loss of function are consistent with possible direct effects on the myelinating potential of oligodendrocyte progenitor cells (OPCs), in addition to OPC-indirect effects involving enhanced astrocyte expression of promyelinating factors, such as BDNF. These findings highlight previously unrecognized roles of PAR1 in myelin regeneration, including integrated actions across the oligodendrocyte and astroglial compartments that are at least partially mechanistically linked to the powerful BDNF-TrkB neurotrophic signaling system. Altogether, findings suggest PAR1 may be a therapeutically tractable target for demyelinating disorders of the CNS.SIGNIFICANCE STATEMENT Replacement of oligodendroglia and myelin regeneration holds tremendous potential to improve function across neurological conditions. Here we demonstrate Protease Activated Receptor 1 (PAR1) is an important regulator of the capacity for myelin regeneration across two experimental murine models of myelin injury. PAR1 is a G-protein-coupled receptor densely expressed in the CNS, however there is limited information regarding its physiological roles in health and disease. Using a combination of PAR1 knock-out mice, oligodendrocyte monocultures and oligodendrocyte-astrocyte cocultures, we demonstrate blocking PAR1 improves myelin production by a mechanism related to effects across glial compartments and linked in part to regulatory actions toward growth factors such as BDNF. These findings set the stage for development of new clinically relevant myelin regeneration strategies.
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Chiha W, Bartlett CA, Petratos S, Fitzgerald M, Harvey AR. Intravitreal application of AAV-BDNF or mutant AAV-CRMP2 protects retinal ganglion cells and stabilizes axons and myelin after partial optic nerve injury. Exp Neurol 2020; 326:113167. [PMID: 31904385 DOI: 10.1016/j.expneurol.2019.113167] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 12/20/2019] [Accepted: 12/31/2019] [Indexed: 12/29/2022]
Abstract
Secondary degeneration following an initial injury to the central nervous system (CNS) results in increased tissue loss and is associated with increasing functional impairment. Unilateral partial dorsal transection of the adult rat optic nerve (ON) has proved to be a useful experimental model in which to study factors that contribute to secondary degenerative events. Using this injury model, we here quantified the protective effects of intravitreally administered bi-cistronic adeno-associated viral (AAV2) vectors encoding either brain derived neurotrophic factor (BDNF) or a mutant, phospho-resistant, version of collapsin response mediator protein 2 (CRMP2T555A) on retinal ganglion cells (RGCs), their axons, and associated myelin. To test for potential synergistic interactions, some animals received combined injections of both vectors. Three months post-injury, all treatments maintained RGC numbers in central retina, but only AAV2-BDNF significantly protected ventrally located RGCs exclusively vulnerable to secondary degeneration. Behaviourally, treatments that involved AAV2-BDNF significantly restored the number of smooth-pursuit phases of optokinetic nystagmus. While all therapeutic regimens preserved axonal density and proportions of typical complexes, including heminodes and single nodes, BDNF treatments were generally more effective in maintaining the length of the node of Ranvier in myelin surrounding ventral ON axons after injury. Both AAV2-BDNF and AAV2-CRMP2T555A prevented injury-induced changes in G-ratio and overall myelin thickness, but only AAV2-BDNF administration protected against large-scale myelin decompaction in ventral ON. In summary, in a model of secondary CNS degeneration, both BDNF and CRMP2T555A vectors were neuroprotective, however different efficacies were observed for these overexpressed proteins in the retina and ON, suggesting disparate cellular and molecular targets driving responses for neural repair. The potential use of these vectors to treat other CNS injuries and pathologies is discussed.
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Affiliation(s)
- Wissam Chiha
- School of Biological Sciences, The University of Western Australia, WA 6009, Australia; Curtin Health Innovation Research Institute, Curtin University, Belmont, WA 6102, Australia
| | - Carole A Bartlett
- School of Biological Sciences, The University of Western Australia, WA 6009, Australia
| | - Steven Petratos
- Department of Neuroscience, Monash University, VIC 3004, Australia
| | - Melinda Fitzgerald
- Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia; Curtin Health Innovation Research Institute, Curtin University, Belmont, WA 6102, Australia
| | - Alan R Harvey
- School of Human Sciences, The University of Western Australia, WA 6009, Australia; Perron Institute for Neurological and Translational Science, Nedlands, WA 6009, Australia.
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Planas-Fontánez TM, Dreyfus CF, Saitta KS. Reactive Astrocytes as Therapeutic Targets for Brain Degenerative Diseases: Roles Played by Metabotropic Glutamate Receptors. Neurochem Res 2020; 45:541-550. [PMID: 31983009 PMCID: PMC7058558 DOI: 10.1007/s11064-020-02968-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 01/13/2020] [Accepted: 01/18/2020] [Indexed: 02/06/2023]
Abstract
Astrocytes are well known to play critical roles in the development and maintenance of the central nervous system (CNS). Moreover, recent reports indicate that these cells are heterogeneous with respect to the molecules they express and the functions they exhibit in the quiescent or activated state. Because astrocytes also contribute to pathology, promising new results raise the possibility of manipulating specific astroglial populations for therapeutic roles. In this mini-review, we highlight the function of metabotropic glutamate receptors (mGluRs), in particular mGluR3 and mGluR5, in reactive astrocytes and relate these to three degenerative CNS diseases: multiple sclerosis, Alzheimer's disease and Amyotrophic Lateral Sclerosis. Previous studies demonstrate that effects of these receptors may be beneficial, but this varies depending on the subtype of receptor, the state of the astrocytes, and the specific disease to which they are exposed. Elucidating the role of mGluRs on astrocytes at specific times during development and disease will provide novel insights in understanding how to best use these to serve as therapeutic targets.
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Affiliation(s)
- Talia M. Planas-Fontánez
- grid.430387.b0000 0004 1936 8796Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, NJ USA ,grid.430387.b0000 0004 1936 8796Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ USA
| | - Cheryl F. Dreyfus
- grid.430387.b0000 0004 1936 8796Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ USA ,grid.430387.b0000 0004 1936 8796Robert Wood Johnson Medical School, 683 Hoes Lane West, Room 361, Piscataway, NJ 08854 USA
| | - Kyle S. Saitta
- grid.430387.b0000 0004 1936 8796Joint Graduate Program in Toxicology, Rutgers, The State University of New Jersey, Piscataway, NJ USA ,grid.430387.b0000 0004 1936 8796Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, NJ USA
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Hunter LE, Freudenberg-Hua Y, Davies P, Kim M, Fleysher R, Stewart WF, Lipton RB, Lipton ML. BDNF Val 66Met Positive Players Demonstrate Diffusion Tensor Imaging Consistent With Impaired Myelination Associated With High Levels of Soccer Heading: Indication of a Potential Gene-Environment Interaction Mechanism. Front Neurol 2019; 10:1297. [PMID: 31920921 PMCID: PMC6918922 DOI: 10.3389/fneur.2019.01297] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 11/25/2019] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study was to examine the potential effect modifying role of the BDNF Val66Met polymorphism on the association of soccer heading with white matter microstructure. We studied 312 players enrolled in the ongoing Einstein Soccer Study, a longitudinal study of amateur soccer player in New York City and surrounding areas. At enrollment and 2 years later, total heading in the prior 12 months (12-mo.) was estimated using an established self-report instrument and diffusion tensor imaging (DTI) was performed. Generalized Estimating Equations (GEE) logistic regression models were employed to test effect modification by the BDNF Val66Met polymorphism on the association between 12-mo. heading exposure and DTI. We identified a significant interaction of 12-mo heading*BDNF Val66Met genotype on the presence of low Radial Diffusivity, a DTI marker associated with myelination. Only Met (+) players demonstrated significantly reduced odds of low RD [OR (95 % CI): -2.36 (-3.53, -1.19)] associated with the highest vs. lowest quartile of 12-mo heading exposure. BDNF Val66Met (+) soccer players with long-term exposure to high levels of heading exhibit less low Radial Diffusivity, suggesting impaired re-myelination may be a substrate of the previously reported association between heading and poor functional outcomes in soccer players.
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Affiliation(s)
- Liane E. Hunter
- The Gruss Magnetic Resonance Research Center, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
| | - Yun Freudenberg-Hua
- Division of Geriatric Psychiatry, Northwell Health, Glen Oaks, NY, United States
- Litwin-Zucker Center for the Study of Alzheimer's Disease, The Feinstein Institute for Medical Research, Northwell Health, Manhasset, NY, United States
| | - Peter Davies
- Division of Geriatric Psychiatry, Northwell Health, Glen Oaks, NY, United States
| | - Mimi Kim
- Department of Epidemiology & Population Health, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
| | - Roman Fleysher
- The Gruss Magnetic Resonance Research Center, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
- Department of Radiology, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
| | | | - Richard B. Lipton
- Department of Epidemiology & Population Health, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
- Department of Neurology, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
- Department of Psychiatry & Behavioral Sciences, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
| | - Michael L. Lipton
- The Gruss Magnetic Resonance Research Center, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
- Department of Radiology, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
- Department of Psychiatry & Behavioral Sciences, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
- The Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine and Montefiore Medical Center, The Bronx, NY, United States
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Metformin-induced AMPK activation stimulates remyelination through induction of neurotrophic factors, downregulation of NogoA and recruitment of Olig2+ precursor cells in the cuprizone murine model of multiple sclerosis. ACTA ACUST UNITED AC 2019; 27:583-592. [PMID: 31620963 DOI: 10.1007/s40199-019-00286-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 06/30/2019] [Indexed: 12/15/2022]
Abstract
PURPOSE Oligodendrocytes (OLGs) damage and myelin distraction is considered as a critical step in many neurological disorders especially multiple sclerosis (MS). Cuprizone (cup) animal model of MS targets OLGs degeneration and frequently used to the mechanistic understanding of de- and remyelination. The aim of this study was exploring the effects of metformin on the OLGs regeneration, myelin repair and profile of neurotrophic factors in the mice brain after cup-induced acute demyelination. METHODS Mice (C57BL/6 J) were fed with chow containing 0.2% cup for 5 weeks to induce specific OLGs degeneration and acute demyelination. Next, the cup was withdrawn to allow one-week recovery (spontaneous remyelination). At the end of this period, mature OLGs markers, myelin-associated neurite outgrowth inhibitor protein A (NogoA), premature specific OLGs transcription factor (Olig2), anti-apoptosis marker (survivin), neurotrophic factors, and AMPK activation were monitored in the presence or absence of metformin (50 mg/kg body weight/day) in the corpus callosum (CC). RESULTS Our finding indicated that consumption of metformin during the recovery period potentially induced an active form of AMPK (p-AMPK) and promoted repopulation of mature OLGs (MOG+ cells, MBP+ cells) in CC through up-regulation of BDNF, CNTF, and NGF as well as down-regulation of NogoA and recruitment of Olig2+ precursor cells. CONCLUSIONS This study for the first time reveals that metformin-induced AMPK, a master regulator of energy homeostasis, activation following toxic demyelination could potentially accelerate regeneration and supports spontaneous demyelination. These findings suggest the development of new therapeutic strategies based on AMPK activation for MS in the near future. Graphical abstract An overview of the possible molecular mechanisms of action of metformin-mediated remyelinationa.
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Creus-Muncunill J, Ehrlich ME. Cell-Autonomous and Non-cell-Autonomous Pathogenic Mechanisms in Huntington's Disease: Insights from In Vitro and In Vivo Models. Neurotherapeutics 2019; 16:957-978. [PMID: 31529216 PMCID: PMC6985401 DOI: 10.1007/s13311-019-00782-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Huntington's disease (HD) is an autosomal dominant disorder caused by an expansion in the trinucleotide CAG repeat in exon-1 in the huntingtin gene, located on chromosome 4. When the number of trinucleotide CAG exceeds 40 repeats, disease invariably is manifested, characterized by motor, cognitive, and psychiatric symptoms. The huntingtin (Htt) protein and its mutant form (mutant huntingtin, mHtt) are ubiquitously expressed but although multiple brain regions are affected, the most vulnerable brain region is the striatum. Striatal medium-sized spiny neurons (MSNs) preferentially degenerate, followed by the cortical pyramidal neurons located in layers V and VI. Proposed HD pathogenic mechanisms include, but are not restricted to, excitotoxicity, neurotrophic support deficits, collapse of the protein degradation mechanisms, mitochondrial dysfunction, transcriptional alterations, and disorders of myelin. Studies performed in cell type-specific and regionally selective HD mouse models implicate both MSN cell-autonomous properties and cell-cell interactions, particularly corticostriatal but also with non-neuronal cell types. Here, we review the intrinsic properties of MSNs that contribute to their selective vulnerability and in addition, we discuss how astrocytes, microglia, and oligodendrocytes, together with aberrant corticostriatal connectivity, contribute to HD pathophysiology. In addition, mHtt causes cell-autonomous dysfunction in cell types other than MSNs. These findings have implications in terms of therapeutic strategies aimed at preventing neuronal dysfunction and degeneration.
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Affiliation(s)
- Jordi Creus-Muncunill
- Department of Neurology, Icahn School of Medicine at Mount Sinai, 1468 Madison Avenue, New York, NY, 10029, USA
| | - Michelle E Ehrlich
- Department of Neurology, Icahn School of Medicine at Mount Sinai, 1468 Madison Avenue, New York, NY, 10029, USA.
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Baaklini CS, Rawji KS, Duncan GJ, Ho MFS, Plemel JR. Central Nervous System Remyelination: Roles of Glia and Innate Immune Cells. Front Mol Neurosci 2019; 12:225. [PMID: 31616249 PMCID: PMC6764409 DOI: 10.3389/fnmol.2019.00225] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Accepted: 09/04/2019] [Indexed: 12/31/2022] Open
Abstract
In diseases such as multiple sclerosis (MS), inflammation can injure the myelin sheath that surrounds axons, a process known as demyelination. The spontaneous regeneration of myelin, called remyelination, is associated with restoration of function and prevention of axonal degeneration. Boosting remyelination with therapeutic intervention is a promising new approach that is currently being tested in several clinical trials. The endogenous regulation of remyelination is highly dependent on the immune response. In this review article, we highlight the cell biology of remyelination and its regulation by innate immune cells. For the purpose of this review, we discuss the roles of microglia, and also astrocytes and oligodendrocyte progenitor cells (OPCs) as they are being increasingly recognized to have immune cell functions.
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Affiliation(s)
- Charbel S Baaklini
- Department of Medicine, Division of Neurology, Neuroscience and Mental Health Institute, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Khalil S Rawji
- Wellcome Trust-Medical Research Council, Cambridge Stem Cell Institute, Cambridge Biomedical Campus, University of Cambridge, Cambridge, United Kingdom
| | - Greg J Duncan
- Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health and Science University, Portland, OR, United States
| | - Madelene F S Ho
- Department of Medicine, Division of Neurology, Neuroscience and Mental Health Institute, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada
| | - Jason R Plemel
- Department of Medicine, Division of Neurology, Neuroscience and Mental Health Institute, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, Canada.,Wellcome Trust-Medical Research Council, Cambridge Stem Cell Institute, Cambridge Biomedical Campus, University of Cambridge, Cambridge, United Kingdom.,Department of Neurology, Jungers Center for Neurosciences Research, Oregon Health and Science University, Portland, OR, United States
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Charkviani M, Muradashvili N, Lominadze D. Vascular and non-vascular contributors to memory reduction during traumatic brain injury. Eur J Neurosci 2019; 50:2860-2876. [PMID: 30793398 PMCID: PMC6703968 DOI: 10.1111/ejn.14390] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 02/06/2019] [Accepted: 02/07/2019] [Indexed: 01/09/2023]
Abstract
Traumatic brain injury (TBI) is an increasing health problem. It is a complex, progressive disease that consists of many factors affecting memory. Studies have shown that increased blood-brain barrier (BBB) permeability initiates pathological changes in neuro-vascular network but the role of cerebrovascular dysfunction and its mediated mechanisms associated with memory reduction during TBI are still not well understood. Changes in BBB, inflammation, extravasation of blood plasma components, activation of neuroglia lead to neurodegeneration. Extravasated proteins such as amyloid-beta, fibrinogen, and cellular prion protein may form degradation resistant complexes that can lead to neuronal dysfunction and degeneration. They also have the ability to activate astrocytes, and thus, can be involved in memory impairment. Understanding the triggering mechanisms and the places they originate in vasculature or in extravascular tissue may help to identify potential therapeutic targets to ameliorate memory reduction during TBI. The goal of this review is to discuss conceptual mechanisms that lead to short-term memory reduction during non-severe TBI considering distinction between vascular and non-vascular effects on neurons. Some aspects of these mechanisms need to be confirmed further. Therefore, we hope that the discussion presented bellow may lead to experiments that may clarify the triggering mechanisms of memory reduction after head trauma.
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Affiliation(s)
- Mariam Charkviani
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY, USA
| | - Nino Muradashvili
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY, USA
- Department of Basic Medicine, Caucasus International University, Tbilisi, Georgia
| | - David Lominadze
- Department of Physiology, University of Louisville, School of Medicine, Louisville, KY, USA
- Kentucky Spinal Cord Research Center, University of Louisville, School of Medicine, Louisville, KY, USA
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63
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Wang Q, Gao R, Wang M, Chen Q, Xiao M, Li Z, Wang L, Chen C. Spatiotemporal expression patterns of Galectin-3 in perinatal rat hypoxic-ischemic brain injury model. Neurosci Lett 2019; 711:134439. [PMID: 31425825 DOI: 10.1016/j.neulet.2019.134439] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/03/2019] [Accepted: 08/15/2019] [Indexed: 12/28/2022]
Abstract
In this research, we intended to evaluate the expression pattern, distribution and sources of Galectin-3 (Gal-3) in perinatal hypoxic-ischemic brain injury rat model. Postnatal day 3 Sprague-Dawley rat pups were subjected to right carotid artery ligation followed by 2.5 h of hypoxia (6% oxygen). Expression and distribution of Gal-3 were evaluated by western blotting and immunofluorescence. Sources of Gal-3 were evaluated by double staining with neuronic, oligodendrocytic, astrocytic, microglial and endotheliocytic markers. Our results indicated Gal-3 significantly upregulated from 12 h and maintained an increasing tendency within 72 h post injury. Although the relative expression of Gal-3 decreased after 72 h, we detected significant differences until 14d. We found Gal-3 started to distribute in cortex and thalamus area and maintained an increasing tendency. Gal-3 could be detected in cortex, thalamus, corpus callosum and hippocampus area at 72 h post injury. After that, expression of Gal-3 in cortex and thalamus area downregulated, the expression in corpus callosum and hippocampus area vanished. We found astrocyte, microglia, neuron and endotheliocyte were sources of Gal-3 in cortex area; astrocyte, microglia and endotheliocyte were sources of Gal-3 in thalamus area; oligodendrocyte precursor cell and endotheliocyte were sources of Gal-3 in corpus callosum; neuron, microglia and endotheliocyte were sources of Gal-3 in hippocampus. In conclusion, we demonstrated spatiotemporal expression patterns of Galectin-3 post perinatal hypoxic-ischemic brain injury in this research.
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Affiliation(s)
- Qian Wang
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai, China; Key Laboratory of Neonatal Diseases, National Health Commission, China
| | - Ruiwei Gao
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai, China; Key Laboratory of Neonatal Diseases, National Health Commission, China
| | - Minjie Wang
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai, China; Key Laboratory of Neonatal Diseases, National Health Commission, China
| | - Qiufan Chen
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai, China; Key Laboratory of Neonatal Diseases, National Health Commission, China
| | - Mili Xiao
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai, China; Key Laboratory of Neonatal Diseases, National Health Commission, China
| | - Zhihua Li
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai, China; Key Laboratory of Neonatal Diseases, National Health Commission, China
| | - Laishuan Wang
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai, China; Key Laboratory of Neonatal Diseases, National Health Commission, China
| | - Chao Chen
- Department of Neonatology, Children's Hospital of Fudan University, Shanghai, China; Key Laboratory of Neonatal Diseases, National Health Commission, China.
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64
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Miguel-Hidalgo JJ, Carter K, Deloach PH, Sanders L, Pang Y. Glucocorticoid-Induced Reductions of Myelination and Connexin 43 in Mixed Central Nervous System Cell Cultures Are Prevented by Mifepristone. Neuroscience 2019; 411:255-269. [PMID: 31163207 PMCID: PMC6664452 DOI: 10.1016/j.neuroscience.2019.05.050] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 05/23/2019] [Accepted: 05/24/2019] [Indexed: 12/23/2022]
Abstract
Repeated stress induces systemic elevations in glucocorticoid levels. Stress is also associated with alterations in central nervous system astrocytes and oligodendrocytes that involve connexins and myelin proteins. Corticosteroid elevation seems a major factor in stress-induced neuropathology. Changes in astrocyte connexins and myelin components may be important mediators for the neurological effects of corticosteroid elevations. Two primary cell culture models, myelination culture from rat embryonic spinal cord (SC) or cerebral cortex (CC) consisting of neurons and glial cells (oligodendrocytes, microglia and astrocytes), and mixed astrocyte-and-oligodendrocyte culture prepared from postnatal rat CC, were used in this study. Cell cultures were treated with either vehicle, corticosterone (CORT) with or without glucocorticoid receptor antagonist mifepristone, or dexamethasone (DEX) during the period of in vitro myelination. Immunoreactivity of astrocyte connexin 43 (Cx43) and oligodendrocyte myelin basic protein (MBP), or the myelination index (co-localization of MBP and phosphorylated neurofilament) was determined by double immunofluorescent labeling. Oligodendrocyte morphology was evaluated by Sholl analysis. Prolonged exposure to CORT or DEX induced dose-dependent reduction of the myelination index, and of immunostaining for MBP and Cx43 in SC and CC myelination cultures, which was prevented by mifepristone. In glial cultures single CORT or DEX exposure caused shrinkage and simplification of/' MBP- or CNPase-positive oligodendrocyte processes. The results support that concurrent effects of glucocorticoids on myelination and astrocyte Cx43 immunoreactivity are mediated by glucocorticoid receptors and may partially account for the involvement of CNS glia in the pathological effects of prolonged stress.
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Affiliation(s)
- José Javier Miguel-Hidalgo
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, 2500 N. State St., Jackson, MS 39216, USA.
| | - Kathleen Carter
- Department of Pediatrics, University of Mississippi Medical Center
| | | | - Leon Sanders
- Department of Psychiatry and Human Behavior, University of Mississippi Medical Center
| | - Yi Pang
- Department of Pediatrics, University of Mississippi Medical Center
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65
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Bronzuoli MR, Facchinetti R, Valenza M, Cassano T, Steardo L, Scuderi C. Astrocyte Function Is Affected by Aging and Not Alzheimer's Disease: A Preliminary Investigation in Hippocampi of 3xTg-AD Mice. Front Pharmacol 2019; 10:644. [PMID: 31244658 PMCID: PMC6562169 DOI: 10.3389/fphar.2019.00644] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 05/17/2019] [Indexed: 01/12/2023] Open
Abstract
Old age is a risk factor for Alzheimer's disease (AD), which is characterized by hippocampal impairment together with substantial changes in glial cell functions. Are these alterations due to the disease progression or are they a consequence of aging? To start addressing this issue, we studied the expression of specific astrocytic and microglial structural and functional proteins in a validated transgenic model of AD (3×Tg-AD). These mice develop both amyloid plaques and neurofibrillary tangles, and initial signs of the AD-like pathology have been documented as early as three months of age. We compared male 3×Tg-AD mice at 6 and 12 months of age with their wild-type age-matched counterparts. We also investigated neurons by examining the expression of both the microtubule-associated protein 2 (MAP2), a neuronal structural protein, and the brain-derived neurotrophic factor (BDNF). The latter is indeed a crucial indicator for synaptic plasticity and neurogenesis/neurodegeneration. Our results show that astrocytes are more susceptible to aging than microglia, regardless of mouse genotype. Moreover, we discovered significant age-dependent alterations in the expression of proteins responsible for astrocyte-astrocyte and astrocyte-neuron communication, as well as a significant age-dependent decline in BDNF expression. Our data promote further research on the unexplored role of astroglia in both physiological and pathological aging.
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Affiliation(s)
- Maria Rosanna Bronzuoli
- Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy
| | - Roberta Facchinetti
- Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy
| | - Marta Valenza
- Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy.,Epitech Group SpA, Saccolongo, Italy
| | - Tommaso Cassano
- Department of Clinical and Experimental Medicine, University of Foggia, Foggia, Italy
| | - Luca Steardo
- Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy
| | - Caterina Scuderi
- Department of Physiology and Pharmacology "V. Erspamer," Sapienza University of Rome, Rome, Italy
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66
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Geraghty AC, Gibson EM, Ghanem RA, Greene JJ, Ocampo A, Goldstein AK, Ni L, Yang T, Marton RM, Paşca SP, Greenberg ME, Longo FM, Monje M. Loss of Adaptive Myelination Contributes to Methotrexate Chemotherapy-Related Cognitive Impairment. Neuron 2019; 103:250-265.e8. [PMID: 31122677 DOI: 10.1016/j.neuron.2019.04.032] [Citation(s) in RCA: 160] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 01/29/2019] [Accepted: 04/22/2019] [Indexed: 01/05/2023]
Abstract
Activity-dependent myelination is thought to contribute to adaptive neurological function. However, the mechanisms by which activity regulates myelination and the extent to which myelin plasticity contributes to non-motor cognitive functions remain incompletely understood. Using a mouse model of chemotherapy-related cognitive impairment (CRCI), we recently demonstrated that methotrexate (MTX) chemotherapy induces complex glial dysfunction for which microglial activation is central. Here, we demonstrate that remote MTX exposure blocks activity-regulated myelination. MTX decreases cortical Bdnf expression, which is restored by microglial depletion. Bdnf-TrkB signaling is a required component of activity-dependent myelination. Oligodendrocyte precursor cell (OPC)-specific TrkB deletion in chemotherapy-naive mice results in impaired cognitive behavioral performance. A small-molecule TrkB agonist rescues both myelination and cognitive impairment after MTX chemotherapy. This rescue after MTX depends on intact TrkB expression in OPCs. Taken together, these findings demonstrate a molecular mechanism required for adaptive myelination that is aberrant in CRCI due to microglial activation.
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Affiliation(s)
- Anna C Geraghty
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Erin M Gibson
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Reem A Ghanem
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Jacob J Greene
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Alfonso Ocampo
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Andrea K Goldstein
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Lijun Ni
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Tao Yang
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Rebecca M Marton
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | - Sergiu P Paşca
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA
| | | | - Frank M Longo
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Michelle Monje
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA; Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, CA 94305, USA; Department of Pathology, Stanford University, Stanford, CA 94305, USA; Department of Pediatrics, Stanford University, Stanford, CA 94305, USA; Institute for Stem Cell Biology and Regenerative Medicine, Stanford University, Stanford, CA 94305, USA.
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67
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Rice J, Gu C. Function and Mechanism of Myelin Regulation in Alcohol Abuse and Alcoholism. Bioessays 2019; 41:e1800255. [PMID: 31094014 DOI: 10.1002/bies.201800255] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 03/31/2019] [Indexed: 12/26/2022]
Abstract
Excessive alcohol use has adverse effects on the central nervous system (CNS) and can lead to alcohol use disorders (AUDs). Recent studies have suggested that myelin reductions may directly contribute to CNS dysfunctions associated with AUDs. Myelin consists of compact lipid membranes wrapped around axons to provide electrical insulation and trophic support. Regulation of myelin is considered as a new form of neural plasticity due to its profound impacts on the computation of neural networks. In this review, the authors first discuss experimental evidence showing how alcohol exposure causes demyelination in different brain regions, often accompanied by deficits in cognition and emotion. Next, they discuss postulated molecular and cellular mechanisms underlying alcohol's impact on myelin. It is clear that more extensive investigations are needed in this important but underexplored research field in order to gain a better understanding of the myelin-behavior relationship and to develop new treatment strategies for AUDs.
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Affiliation(s)
- James Rice
- Department of Biological Chemistry and Pharmacology, The Ohio State University, 1060 Carmack Road, Columbus, OH, 43210, USA
| | - Chen Gu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, 1060 Carmack Road, Columbus, OH, 43210, USA
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68
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Pöyhönen S, Er S, Domanskyi A, Airavaara M. Effects of Neurotrophic Factors in Glial Cells in the Central Nervous System: Expression and Properties in Neurodegeneration and Injury. Front Physiol 2019; 10:486. [PMID: 31105589 PMCID: PMC6499070 DOI: 10.3389/fphys.2019.00486] [Citation(s) in RCA: 139] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 04/08/2019] [Indexed: 12/28/2022] Open
Abstract
Astrocytes, oligodendrocytes, and microglia are abundant cell types found in the central nervous system and have been shown to play crucial roles in regulating both normal and disease states. An increasing amount of evidence points to the critical importance of glia in mediating neurodegeneration in Alzheimer’s and Parkinson’s diseases (AD, PD), and in ischemic stroke, where microglia are involved in initial tissue clearance, and astrocytes in the subsequent formation of a glial scar. The importance of these cells for neuronal survival has previously been studied in co-culture experiments and the search for neurotrophic factors (NTFs) initiated after finding that the addition of conditioned media from astrocyte cultures could support the survival of primary neurons in vitro. This led to the discovery of the potent dopamine neurotrophic factor, glial cell line-derived neurotrophic factor (GDNF). In this review, we focus on the relationship between glia and NTFs including neurotrophins, GDNF-family ligands, CNTF family, and CDNF/MANF-family proteins. We describe their expression in astrocytes, oligodendrocytes and their precursors (NG2-positive cells, OPCs), and microglia during development and in the adult brain. Furthermore, we review existing data on the glial phenotypes of NTF knockout mice and follow NTF expression patterns and their effects on glia in disease models such as AD, PD, stroke, and retinal degeneration.
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Affiliation(s)
- Suvi Pöyhönen
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Safak Er
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Andrii Domanskyi
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Mikko Airavaara
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland.,Neuroscience Center, HiLIFE, University of Helsinki, Helsinki, Finland
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69
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Abstract
This review discusses the potential role that glial cells may play in influencing the relationship between exercise and episodic memory function. A narrative review methodology is employed. Herein, the different types of glial cells, their implications in subserving episodic memory function, and how exercise can modulate glial cell activity, particularly astrocyte functionality, are discussed. Although additional experimental work is needed, astrocytes appear to play an important role in the exercise-memory interaction. Exercise may increase astrocytic size, attenuate astrogliodegeneration, improve astrocytic aquaporin-4 expression, and increase astrocytic transporter levels. These effects, in turn, may help to increase the number of synapses that neurons form, increase the number of synaptic structures, and increase presynaptic function and postsynaptic receptor localization. Ultimately, these effects may help influence long-term potentiation and episodic memory function.
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Affiliation(s)
- P D Loprinzi
- 1 Exercise & Memory Laboratory, Department of Health, Exercise Science, and Recreation Management, The University of Mississippi , University, MS, USA
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70
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Contreras-Zárate MJ, Day NL, Ormond DR, Borges VF, Tobet S, Gril B, Steeg PS, Cittelly DM. Estradiol induces BDNF/TrkB signaling in triple-negative breast cancer to promote brain metastases. Oncogene 2019; 38:4685-4699. [PMID: 30796353 PMCID: PMC6565485 DOI: 10.1038/s41388-019-0756-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 01/10/2019] [Accepted: 01/23/2019] [Indexed: 12/31/2022]
Abstract
Breast cancer brain metastases (BM) affect younger women disproportionally, including those lacking estrogen receptor (ER), progesterone receptor, and HER2 (known as triple-negative breast cancer; TNBC). Previous studies in preclinical models showed that pre-menopausal levels of estradiol (E2) promote TNBC-BM through incompletely understood mechanisms involving reactive astrocytes. Herein, a novel mechanism involving E2-dependent upregulation of brain-derived neurotrophic factor (BDNF) in astrocytes, and subsequent activation of tumor cell tropomyosin kinase receptor B (TrkB), is identified. E2 increased experimental BM of TNBC 4T1BR5 and E0771 cells by 21 and 3.6 fold, respectively, compared to E2-depleted mice. ERα+ reactive astrocytes were found at early and late stages of BM, and E2 upregulated BDNF in ER+ reactive astrocytes in vitro and in vivo. TrkB was expressed in TNBC brain-trophic cell lines, BM-patient-derived xenografts, and breast cancer BM. Conditioned media from E2-treated astrocytes (CM-E2) activated TrkB and downstream AKT, ERK, and PLC-γ signaling in TNBC cells, increasing their invasiveness and tumor-initiating capability in vitro. The promotion of BM by E2-activated astrocytes was found to be more complex, involving feedback loops and other receptor tyrosine kinases. In 4T1BR5 cells, there was a positive feedback loop whereby astrocytic BDNF induced cancer cell BDNF translation. Upregulation of cancer cell BDNF was required to promote full invasiveness of 4T1BR5 in response to CM-E2, and was observed in brain metastatic cells in E2-treated mice in vivo. Moreover, the non-competitive BDNF/TrkB inhibitor ANA-12 reduced E2-induced 4T1BR5 BM to levels similar to OVX mice. BDNF also activated EGFR in TrkB+EGFR+ TNBC cells, suggesting that E2 action through astrocytes activates redundant pathways promoting BM. These findings have important therapeutic implications, as they provide a rationale to use E2-depletion therapies or TrkB inhibitors to prevent or delay development of BM in younger women.
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Affiliation(s)
- Maria J Contreras-Zárate
- Department of Pathology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Nicole L Day
- Department of Pathology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - D Ryan Ormond
- Department of Neurosurgery, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Virginia F Borges
- Department of Medicine, Division of Medical Oncology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Stuart Tobet
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Brunilde Gril
- Women's Malignancies Branch, National Cancer Institute, Bethesda, MD, USA
| | - Patricia S Steeg
- Women's Malignancies Branch, National Cancer Institute, Bethesda, MD, USA
| | - Diana M Cittelly
- Department of Pathology, University of Colorado Denver, Anschutz Medical Campus, Aurora, CO, USA.
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71
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Zhou Z, Ikegaya Y, Koyama R. The Astrocytic cAMP Pathway in Health and Disease. Int J Mol Sci 2019; 20:E779. [PMID: 30759771 PMCID: PMC6386894 DOI: 10.3390/ijms20030779] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 02/06/2019] [Accepted: 02/08/2019] [Indexed: 12/11/2022] Open
Abstract
Astrocytes are major glial cells that play critical roles in brain homeostasis. Abnormalities in astrocytic functions can lead to brain disorders. Astrocytes also respond to injury and disease through gliosis and immune activation, which can be both protective and detrimental. Thus, it is essential to elucidate the function of astrocytes in order to understand the physiology of the brain to develop therapeutic strategies against brain diseases. Cyclic adenosine monophosphate (cAMP) is a major second messenger that triggers various downstream cellular machinery in a wide variety of cells. The functions of astrocytes have also been suggested as being regulated by cAMP. Here, we summarize the possible roles of cAMP signaling in regulating the functions of astrocytes. Specifically, we introduce the ways in which cAMP pathways are involved in astrocyte functions, including (1) energy supply, (2) maintenance of the extracellular environment, (3) immune response, and (4) a potential role as a provider of trophic factors, and we discuss how these cAMP-regulated processes can affect brain functions in health and disease.
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Affiliation(s)
- Zhiwen Zhou
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan.
- Center for Information and Neural Networks, Suita City, Osaka 565-0871, Japan.
| | - Ryuta Koyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo 113-0033, Japan.
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72
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Conditional BDNF Delivery from Astrocytes Rescues Memory Deficits, Spine Density, and Synaptic Properties in the 5xFAD Mouse Model of Alzheimer Disease. J Neurosci 2019; 39:2441-2458. [PMID: 30700530 DOI: 10.1523/jneurosci.2121-18.2019] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Revised: 01/23/2019] [Accepted: 01/25/2019] [Indexed: 12/25/2022] Open
Abstract
It has been well documented that neurotrophins, including brain-derived neurotrophic factor (BDNF), are severely affected in Alzheimer's disease (AD), but their administration faces a myriad of technical challenges. Here we took advantage of the early astrogliosis observed in an amyloid mouse model of AD (5xFAD) and used it as an internal sensor to administer BDNF conditionally and locally. We first demonstrate the relevance of BDNF release from astrocytes by evaluating the effects of coculturing WT neurons and BDNF-deficient astrocytes. Next, we crossed 5xFAD mice with pGFAP:BDNF mice (only males were used) to create 5xFAD mice that overexpress BDNF when and where astrogliosis is initiated (5xF:pGB mice). We evaluated the behavioral phenotype of these mice. We first found that BDNF from astrocytes is crucial for dendrite outgrowth and spine number in cultured WT neurons. Double-mutant 5xF:pGB mice displayed improvements in cognitive tasks compared with 5xFAD littermates. In these mice, there was a rescue of BDNF/TrkB downstream signaling activity associated with an improvement of dendritic spine density and morphology. Clusters of synaptic markers, PSD-95 and synaptophysin, were also recovered in 5xF:pGB compared with 5xFAD mice as well as the number of presynaptic vesicles at excitatory synapses. Additionally, experimentally evoked LTP in vivo was increased in 5xF:pGB mice. The beneficial effects of conditional BDNF production and local delivery at the location of active neuropathology highlight the potential to use endogenous biomarkers with early onset, such as astrogliosis, as regulators of neurotrophic therapy in AD.SIGNIFICANCE STATEMENT Recent evidence places astrocytes as pivotal players during synaptic plasticity and memory processes. In the present work, we first provide evidence that astrocytes are essential for neuronal morphology via BDNF release. We then crossed transgenic mice (5xFAD mice) with the transgenic pGFAP-BDNF mice, which express BDNF under the GFAP promoter. The resultant double-mutant mice 5xF:pGB mice displayed a full rescue of hippocampal BDNF loss and related signaling compared with 5xFAD mice and a significant and specific improvement in all the evaluated cognitive tasks. These improvements did not correlate with amelioration of β amyloid load or hippocampal adult neurogenesis rate but were accompanied by a dramatic recovery of structural and functional synaptic plasticity.
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73
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Vejar S, Oyarzún JE, Retamal MA, Ortiz FC, Orellana JA. Connexin and Pannexin-Based Channels in Oligodendrocytes: Implications in Brain Health and Disease. Front Cell Neurosci 2019; 13:3. [PMID: 30760982 PMCID: PMC6361860 DOI: 10.3389/fncel.2019.00003] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 01/07/2019] [Indexed: 11/13/2022] Open
Abstract
Oligodendrocytes are the myelin forming cells in the central nervous system (CNS). In addition to this main physiological function, these cells play key roles by providing energy substrates to neurons as well as information required to sustain proper synaptic transmission and plasticity at the CNS. The latter requires a fine coordinated intercellular communication with neurons and other glial cell types, including astrocytes. In mammals, tissue synchronization is mainly mediated by connexins and pannexins, two protein families that underpin the communication among neighboring cells through the formation of different plasma membrane channels. At one end, gap junction channels (GJCs; which are exclusively formed by connexins in vertebrates) connect the cytoplasm of contacting cells allowing electrical and metabolic coupling. At the other end, hemichannels and pannexons (which are formed by connexins and pannexins, respectively) communicate the intra- and extracellular compartments, serving as diffusion pathways of ions and small molecules. Here, we briefly review the current knowledge about the expression and function of hemichannels, pannexons and GJCs in oligodendrocytes, as well as the evidence regarding the possible role of these channels in metabolic and synaptic functions at the CNS. In particular, we focus on oligodendrocyte-astrocyte coupling during axon metabolic support and its implications in brain health and disease.
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Affiliation(s)
- Sebastián Vejar
- Mechanisms of Myelin Formation and Repair Laboratory, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Juan E Oyarzún
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile.,Department of Cell Physiology and Molecular Biophysics, and Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Fernando C Ortiz
- Mechanisms of Myelin Formation and Repair Laboratory, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Pontificia Universidad Católica de Chile, Santiago, Chile
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74
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Inhibition of activated astrocyte ameliorates lipopolysaccharide- induced depressive-like behaviors. J Affect Disord 2019; 242:52-59. [PMID: 30172225 DOI: 10.1016/j.jad.2018.08.015] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 07/05/2018] [Accepted: 08/07/2018] [Indexed: 12/19/2022]
Abstract
BACKGROUND Numerous studies indicate that inflammation plays important roles in the development of depression. Astrocytes are crucial regulators of immune response in the central nervous system, and strongly activated by pro-inflammatory cytokines. We hypothesized that inhibition of activated astrocytes contributed to ameliorate depressive-like symptoms. METHODS This study evaluated the antidepressant-like effect of inhibition of activated astrocytes, by a well-established astrocyte inactivator fluorocitrate (FC), on a lipopolysaccharide (LPS)-induced model of depression. Forced swim test (FST), tail suspension test (TST) and sucrose preference test were used to assess depressive-like behaviors. The expression of fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and neuroinflammation were determined in the hippocampus and cortex. RESULTS The results demonstrated that LPS increased immobility time in the TST and FST, reduced sucrose preference as well. LPS also enhanced the expression of IL-1β, TNF-α, iNOS and GFAP, accompanying with decreased expression of BDNF in the hippocampus and cortex. Inhibition of activated astrocytes by FC significantly prevented LPS- induced alteration in the FST, TST and sucrose preference test. Moreover, in the hippocampus and cortex, inhibition of activated astrocytes by FC significantly attenuated increases of neuroinflammation and GFAP whereas reversed decrease of BDNF in LPS- challenged depression. CONCLUSIONS Taken together, the results suggest that inhibition of activated astrocytes ameliorates LPS-induced depressive-like behavior, providing the first evidence that inhibition of activated astrocytes might represent a novel therapeutic target for depression.
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75
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Siddiqui S, Kamal A, Khan F, Jamali KS, Saify ZS. Gallic and vanillic acid suppress inflammation and promote myelination in an in vitro mouse model of neurodegeneration. Mol Biol Rep 2018; 46:997-1011. [PMID: 30569390 DOI: 10.1007/s11033-018-4557-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 12/06/2018] [Indexed: 11/29/2022]
Abstract
Neuroinflammation affects millions of people around the world as a result of injury or stress. Neuroinflammation represents almost all types of neurological diseases such as multiple sclerosis and Alzheimer's disease. Neurodegenerative diseases comprise demyelination and synaptic loss. The inflammatory response is further propagated by the activation of glial cells and modulation of constitutively expressed extracellular matrix proteins. The aim of the present study was to identify the anti-inflammatory effects of purified compounds gallic acid (GA, 1.0 µM) and vanillic acid (VA, 0.2 µM) on the lysolecithin (LPC, 0.003%)-induced model of inflammation. Hippocampal neurons were co-cultured with glial cells, and LPC was added to induce inflammation. Neurite outgrowth was measured by morphometry software. The level of myelination and demyelination was identified by immunostaining and sodium dodecyl sulfate polyacrylamide gel electrophoresis and western blotting techniques using different antibodies. Whole-cell patch clamp recordings were used to observe the sustained repetitive firing pattern. The data showed that GA and VA significantly increased the neurite outgrowth after 48 h in culture. Both compounds significantly reduced the expression of cyclooxygenase-2, NFκB, tenascin-C, chondroitin sulfate proteoglycans and glial fibrillary acidic protein in astrocytes in the LPC-induced model of inflammation. The level of myelin protein in neurites and oligodendrocyte cell bodies was significantly upregulated by GA and VA treatment. The reduction in sustained repetitive firing in the LPC-induced model of inflammation was reversed by both GA and VA treatment. This study supports the hypothesis that VA and GA have anti-inflammatory activities and could be regarded as potential treatments for neurodegenerative disease.
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Affiliation(s)
- Sonia Siddiqui
- Institute of Biomedical Sciences, Dow University of Health Sciences, Karachi, Pakistan. .,Department of Neuroscience, Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan.
| | - Aisha Kamal
- Department of Neuroscience, Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
| | - Faisal Khan
- Department of Neuroscience, Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
| | | | - Zafar Saeed Saify
- HEJ Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Pakistan
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76
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Fletcher JL, Murray SS, Xiao J. Brain-Derived Neurotrophic Factor in Central Nervous System Myelination: A New Mechanism to Promote Myelin Plasticity and Repair. Int J Mol Sci 2018; 19:ijms19124131. [PMID: 30572673 PMCID: PMC6321406 DOI: 10.3390/ijms19124131] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 12/18/2018] [Accepted: 12/18/2018] [Indexed: 12/27/2022] Open
Abstract
Brain-derived neurotrophic factor (BDNF) plays vitally important roles in neural development and plasticity in both health and disease. Recent studies using mutant mice to selectively manipulate BDNF signalling in desired cell types, in combination with animal models of demyelinating disease, have demonstrated that BDNF not only potentiates normal central nervous system myelination in development but enhances recovery after myelin injury. However, the precise mechanisms by which BDNF enhances myelination in development and repair are unclear. Here, we review some of the recent progress made in understanding the influence BDNF exerts upon the myelinating process during development and after injury, and discuss the cellular and molecular mechanisms underlying its effects. In doing so, we raise new questions for future research.
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Affiliation(s)
- Jessica L Fletcher
- Department of Anatomy and Neuroscience, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, 3010, VIC, Australia.
| | - Simon S Murray
- Department of Anatomy and Neuroscience, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, 3010, VIC, Australia.
| | - Junhua Xiao
- Department of Anatomy and Neuroscience, School of Biomedical Sciences, Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, Parkville, 3010, VIC, Australia.
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77
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Luca A, Calandra C, Luca M. Molecular Bases of Alzheimer's Disease and Neurodegeneration: The Role of Neuroglia. Aging Dis 2018; 9:1134-1152. [PMID: 30574424 PMCID: PMC6284765 DOI: 10.14336/ad.2018.0201] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Accepted: 02/01/2018] [Indexed: 12/13/2022] Open
Abstract
Neuroglia is an umbrella term indicating different cellular types that play a pivotal role in the brain, being involved in its development and functional homeostasis. Glial cells are becoming the focus of recent researches pertaining the pathogenesis of neurodegenerative disorders, Alzheimer's Disease (AD) in particular. In fact, activated microglia is the main determinant of neuroinflammation, contributing to neurodegeneration. In addition, the oxidative insult occurring during pathological brain aging can activate glial cells that, in turn, can favor the production of free radicals. Moreover, the recent Glycogen Synthase Kinase 3 (GSK-3) hypothesis of AD suggests that GSK3, involved in the regulation of glial cells functioning, could exert a role in amyloid deposition and tau hyper-phosphorylation. In this review, we briefly describe the main physiological functions of the glial cells and discuss the link between neuroglia and the most studied molecular bases of AD. In addition, we dedicate a section to the glial changes occurring in AD, with particular attention to their role in terms of neurodegeneration. In the light of the literature data, neuroglia could play a fundamental role in AD pathogenesis and progression. Further studies are needed to shed light on this topic.
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Affiliation(s)
- Antonina Luca
- Department of Medical and Surgical Sciences and Advanced Technologies “G.F. Ingrassia”, University Hospital Policlinico-Vittorio Emanuele, Catania, 95100 Sicily, Italy
| | - Carmela Calandra
- Department of Medical and Surgical Sciences and Advanced Technologies “G.F. Ingrassia”, University Hospital Policlinico-Vittorio Emanuele, Catania, 95100 Sicily, Italy
| | - Maria Luca
- Department of General Surgery and Medical-Surgical Specialties, Dermatology Clinic, University Hospital Policlinico-Vittorio Emanuele, Catania, 95100 Sicily, Italy
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78
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Antigen-presenting cell diversity for T cell reactivation in central nervous system autoimmunity. J Mol Med (Berl) 2018; 96:1279-1292. [PMID: 30386908 DOI: 10.1007/s00109-018-1709-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 10/19/2018] [Accepted: 10/24/2018] [Indexed: 12/13/2022]
Abstract
Autoreactive T cells are considered the major culprits in the pathogenesis of many autoimmune diseases like multiple sclerosis (MS). Upon activation in the lymphoid organs, autoreactive T cells migrate towards the central nervous system (CNS) and target the myelin sheath-forming oligodendrocytes, resulting in detrimental neurological symptoms. Despite the availability of extensively studied systems like the experimental autoimmune encephalomyelitis (EAE) model, our understanding of this disease and the underlying pathogenesis is still elusive. One vividly discussed subject represents the T cell reactivation in the CNS. In order to exert their effector functions in the CNS, autoreactive T cells must encounter antigen-presenting cells (APCs). This interaction provides an antigen-restricted stimulus in the context of major histocompatibility complex class II (MHC-II) and other co-stimulatory molecules. Peripherally derived dendritic cells (DCs), B cells, border-associated macrophages (BAM), CNS-resident microglia, and astrocytes have the capacity to express molecules required for antigen presentation under inflammatory conditions. Also, endothelial cells can fulfill these prerequisites in certain situations. Which of these cells in fact act as APCs for T cell reactivation and to which extent they can exert this function has been studied intensively, but unfortunately with no firm conclusion. In this review, we will summarize the findings that support or question the antigen presenting capacities of the mentioned cell types of CNS-localized T cell reactivation.
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79
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Craddock TJA, Michalovicz LT, Kelly KA, Rice MA, Miller DB, Klimas NG, Morris M, O'Callaghan JP, Broderick G. A Logic Model of Neuronal-Glial Interaction Suggests Altered Homeostatic Regulation in the Perpetuation of Neuroinflammation. Front Cell Neurosci 2018; 12:336. [PMID: 30374291 PMCID: PMC6196274 DOI: 10.3389/fncel.2018.00336] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Accepted: 09/12/2018] [Indexed: 11/21/2022] Open
Abstract
Aberrant inflammatory signaling between neuronal and glial cells can develop into a persistent sickness behavior-related disorders, negatively impacting learning, memory, and neurogenesis. While there is an abundance of literature describing these interactions, there still lacks a comprehensive mathematical model describing the complex feed-forward and feedback mechanisms of neural-glial interaction. Here we compile molecular and cellular signaling information from various studies and reviews in the literature to create a logically-consistent, theoretical model of neural-glial interaction in the brain to explore the role of neuron-glia homeostatic regulation in the perpetuation of neuroinflammation. Logic rules are applied to this connectivity diagram to predict the system's homeostatic behavior. We validate our model predicted homeostatic profiles against RNAseq gene expression profiles in a mouse model of stress primed neuroinflammation. A meta-analysis was used to calculate the significance of similarity between the inflammatory profiles of mice exposed to diisopropyl fluorophostphate (DFP) [with and without prior priming by the glucocorticoid stress hormone corticosterone (CORT)], with the equilibrium states predicted by the model, and to provide estimates of the degree of the neuroinflammatory response. Beyond normal homeostatic regulation, our model predicts an alternate self-perpetuating condition consistent with chronic neuroinflammation. RNAseq gene expression profiles from the cortex of mice exposed to DFP and CORT+DFP align with this predicted state of neuroinflammation, whereas the alignment to CORT alone was negligible. Simulations of putative treatment strategies post-exposure were shown to be theoretically capable of returning the system to a state of typically healthy regulation with broad-acting anti-inflammatory agents showing the highest probability of success. The results support a role for the brain's own homeostatic drive in perpetuating the chronic neuroinflammation associated with exposure to the organophosphate DFP, with and without CORT priming. The deviation of illness profiles from exact model predictions suggests the presence of additional factors or of lasting changes to the brain's regulatory circuitry specific to each exposure.
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Affiliation(s)
- Travis J A Craddock
- Department of Psychology & Neuroscience, Nova Southeastern University, Ft. Lauderdale, FL, United States.,Institute for Neuro-Immune Medicine, Nova Southeastern University, Ft. Lauderdale, FL, United States.,Department of Computer Science, Nova Southeastern University, Ft. Lauderdale, FL, United States.,Department of Clinical Immunology, Nova Southeastern University, Ft. Lauderdale, FL, United States
| | - Lindsay T Michalovicz
- Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, United States
| | - Kimberly A Kelly
- Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, United States
| | - Mark A Rice
- Institute for Neuro-Immune Medicine, Nova Southeastern University, Ft. Lauderdale, FL, United States
| | - Diane B Miller
- Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, United States
| | - Nancy G Klimas
- Institute for Neuro-Immune Medicine, Nova Southeastern University, Ft. Lauderdale, FL, United States.,Department of Clinical Immunology, Nova Southeastern University, Ft. Lauderdale, FL, United States.,Miami Veterans Affairs Medical Center, Miami, FL, United States
| | - Mariana Morris
- Institute for Neuro-Immune Medicine, Nova Southeastern University, Ft. Lauderdale, FL, United States.,Department of Clinical Immunology, Nova Southeastern University, Ft. Lauderdale, FL, United States
| | - James P O'Callaghan
- Health Effects Laboratory Division, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, United States
| | - Gordon Broderick
- Department of Psychology & Neuroscience, Nova Southeastern University, Ft. Lauderdale, FL, United States.,Institute for Neuro-Immune Medicine, Nova Southeastern University, Ft. Lauderdale, FL, United States.,Center for Clinical Systems Biology, Rochester General Hospital, Rochester, NY, United States
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80
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Zhang H, He X, Mei Y, Ling Q. Ablation of ErbB4 in parvalbumin-positive interneurons inhibits adult hippocampal neurogenesis through down-regulating BDNF/TrkB expression. J Comp Neurol 2018; 526:2482-2492. [PMID: 30329159 DOI: 10.1002/cne.24506] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2018] [Revised: 07/06/2018] [Accepted: 07/24/2018] [Indexed: 12/20/2022]
Abstract
Parvalbumin (PV) positive interneurons in the subgranular zone (SGZ) can regulate adult hippocampal neurogenesis. ErbB4 is mainly expressed in PV neurons in the hippocampus and is crucial for keeping normal function of PV neurons. However, whether ErbB4 in PV interneurons affects the adult hippocampal neurogenesis remains unknown. In the present study, we deleted ErbB4 specifically in PV neurons by crossing PV-Cre mice with ErbB4f/f mice. Results of BrdU labeling and NeuN staining revealed that the proliferation of neural progenitors was increased but the survival and maturation of newborn neurons were decreased in the hippocampus of mice after deleting ErbB4 in PV neurons, suggesting that ErbB4 in PV neurons is closely associated with the process of adult hippocampal neurogenesis. Interestingly, the expression of brain-derived neurotrophic factor (BDNF) and its receptor, tropomyosin-related kinase B (TrkB), was significantly decreased in the hippocampus of ErbB4-deleted mice. Together, our data suggested that ErbB4 in PV neurons might modulate adult hippocampal neurogenesis by affecting BDNF-TrkB signaling pathway.
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Affiliation(s)
- Heng Zhang
- Department of Basic Medicine, School of Medicine, Shaoxing University, Shaoxing, Zhejiang, China.,Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Key Laboratory of Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Xiao He
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Key Laboratory of Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Department of Nuclear Medicine, The Second Hospital of Zhejiang University School of Medicine, Hangzhou, Zhejiang, China.,Zhejiang University Medical PET Center, Hangzhou, Zhejiang, China
| | - Yufei Mei
- Department of Neurobiology, Key Laboratory of Medical Neurobiology (Ministry of Health of China), Key Laboratory of Neurobiology of Zhejiang Province, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Qingzhou Ling
- Human resources office, Shaoxing University, Shaoxing, Zhejiang, China
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81
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Gómez-Pinedo U, Duran-Moreno M, Sirerol-Piquer S, Matias-Guiu J. Myelin changes in Alexander disease. NEUROLOGÍA (ENGLISH EDITION) 2018. [DOI: 10.1016/j.nrleng.2017.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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82
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Targeting TrkB with a Brain-Derived Neurotrophic Factor Mimetic Promotes Myelin Repair in the Brain. J Neurosci 2018; 38:7088-7099. [PMID: 29976621 DOI: 10.1523/jneurosci.0487-18.2018] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 06/01/2018] [Accepted: 06/25/2018] [Indexed: 12/22/2022] Open
Abstract
Methods to promote myelin regeneration in response to central myelin loss are essential to prevent the progression of clinical disability in demyelinating diseases. The neurotrophin brain-derived neurotrophic factor (BDNF) is known to promote myelination during development via oligodendrocyte expressed TrkB receptors. Here, we use a structural mimetic of BDNF to promote myelin regeneration in a preclinical mouse model of central demyelination. In female mice, we show that selective targeting of TrkB with the BDNF-mimetic enhances remyelination, increasing oligodendrocyte differentiation, the frequency of myelinated axons, and myelin sheath thickness after a demyelinating insult. Treatment with exogenous BDNF exerted an attenuated effect, increasing myelin sheath thickness only. Further, following conditional deletion of TrkB from premyelinating oligodendrocytes, we show the effects of the BDNF-mimetic on oligodendrocyte differentiation and remyelination are lost, indicating these are dependent on oligodendrocyte expression of TrkB. Overall, these studies demonstrate that targeting oligodendrocyte TrkB promotes in vivo remyelination in the brain.SIGNIFICANCE STATEMENT Novel strategies to promote myelin regeneration are required to prevent progressive neurodegeneration and clinical disability in patients with central demyelinating disease. Here, we test whether selectively targeting the TrkB receptor on the myelin-producing oligodendrocytes, can promote remyelination in the brain. Using a structural mimetic of its native ligand, BDNF, we show that stimulation of TrkB enhances remyelination, increasing oligodendrocyte differentiation, the frequency of myelinated axons and thickness of the myelin sheath following a demyelinating insult. Further, we show that these effects are dependent on the phosphorylation of oligodendrocyte expressed TrkB receptors in vivo Overall, we demonstrate that selective targeting of TrkB has therapeutic potential to promote remyelination in the brain.
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83
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Wang Q, Wang Z, Tian Y, Zhang H, Fang Y, Yu Z, Wang W, Xie M, Ding F. Inhibition of Astrocyte Connexin 43 Channels Facilitates the Differentiation of Oligodendrocyte Precursor Cells Under Hypoxic Conditions In Vitro. J Mol Neurosci 2018; 64:591-600. [PMID: 29623602 PMCID: PMC6763517 DOI: 10.1007/s12031-018-1061-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 03/06/2018] [Indexed: 12/15/2022]
Abstract
Oligodendrocyte precursor cells (OPCs) proliferation and differentiation are essential for remyelination after white matter injury. Astrocytes could promote oligodendrogenesis after white matter damage whereas the underlying mechanisms are unknown. In this study, the role of astrocytic connexin43 (Cx43) hemichannels involved in OPC proliferation and differentiation in chronic hypoxia was evaluated. In an astrocyte-OPC co-culture chronic hypoxia model, OPCs became proliferative but failed to mature into oligodendrocytes. Application of astrocytic Cx43 blockers attenuated astrocyte activation, suppressed Cx43 hemichannel uptake activity and glutamate release induced by hypoxia, as well as improved OPC differentiation. Moreover, AMPA but not NMDA glutamate receptor antagonist rescued OPC differentiation in hypoxia. In conclusion, these findings suggested that astrocytic Cx43 hemichannel inhibition could potentially improve OPC maturation by attenuating AMPAR-mediated glutamate signaling. Astrocytic Cx43 hemichannels could serve as a potential therapeutic target for remyelination after chronic hypoxia.
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Affiliation(s)
- Qiong Wang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | - Zhen Wang
- Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | - Yeye Tian
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | - Huaqiu Zhang
- Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | - Yongkang Fang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | - Zhiyuan Yu
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | - Wei Wang
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China.,Key Laboratory of Neurological Diseases of Chinese Ministry of Education, the School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | - Minjie Xie
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China.,Key Laboratory of Neurological Diseases of Chinese Ministry of Education, the School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China
| | - Fengfei Ding
- Department of Neurology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, People's Republic of China.
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84
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Matías-Guíu J, Oreja-Guevara C, Matias-Guiu J, Gomez-Pinedo U. Vitamin D and remyelination in multiple sclerosis. NEUROLOGÍA (ENGLISH EDITION) 2018. [DOI: 10.1016/j.nrleng.2016.05.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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85
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Liu SH, Lai YL, Chen BL, Yang FY. Ultrasound Enhances the Expression of Brain-Derived Neurotrophic Factor in Astrocyte Through Activation of TrkB-Akt and Calcium-CaMK Signaling Pathways. Cereb Cortex 2018; 27:3152-3160. [PMID: 27252349 DOI: 10.1093/cercor/bhw169] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Low-intensity pulsed ultrasound (LIPUS) stimulation has been shown to increase the expression of brain-derived neurotrophic factor (BDNF) in astrocytes of an in vitro model and rat brains of an in vivo model; however, their molecular mechanisms are still not well clarified. Here, we investigated the underlying mechanisms of BDNF enhancement by LIPUS in rat cerebral cortex astrocytes. After LIPUS stimulation in astrocytes, the protein and mRNA expressions were measured by western blot and RT-PCR, respectively. The concentration of intracellular calcium was determined spectrophotometrically. The results showed that LIPUS enhanced the phosphorylation of tropomyosin-related kinase B (TrkB) and Akt but had no effect on Erk1/2 phosphorylation. Additionally, LIPUS increased the intracellular concentration of calcium and enhanced the protein levels of calmodulin-dependent kinase (CaMK) II and CaMKIV. LIPUS also activated the phosphorylation of NF-κB-p65 but did not promote the activation of cAMP response element-binding protein (CREB). Taken together, our results suggest that LIPUS stimulation upregulates BDNF production in astrocytes through the activation of NF-κB via the TrkB/PI3K/Akt and calcium/CaMK signaling pathways. BDNF has emerged as a major molecular player in the regulation of neural circuit development and function. Therefore, LIPUS stimulation may play a crucial and beneficial role in neurodegenerative diseases.
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Affiliation(s)
- Shing-Hwa Liu
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan.,Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
| | - Yi-Long Lai
- Department of Biomedical Imaging and Radiological Sciences
| | - Bo-Lin Chen
- Institute of Toxicology, College of Medicine, National Taiwan University, Taipei, Taiwan
| | - Feng-Yi Yang
- Department of Biomedical Imaging and Radiological Sciences.,Biophotonics and Molecular Imaging Research Center.,Biomedical Engineering Research and Development Center, National Yang-Ming University, Taipei, Taiwan
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86
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Abstract
The role traditionally assigned to astrocytes in the pathogenesis of multiple sclerosis (MS) lesions has been the formation of the glial scar once inflammation has subsided. Astrocytes are now recognized to be early and highly active players during lesion formation and key for providing peripheral immune cells access to the central nervous system. Here, we review the role of astrocytes in the formation and evolution of MS lesions, including the recently described functional polarization of astrocytes, discuss prototypical pathways for astrocyte activation, and summarize mechanisms by which MS treatments affect astrocyte function.
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Affiliation(s)
- Gerald Ponath
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
| | - Calvin Park
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
| | - David Pitt
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
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87
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Cragnolini AB, Montenegro G, Friedman WJ, Mascó DH. Brain-region specific responses of astrocytes to an in vitro injury and neurotrophins. Mol Cell Neurosci 2018; 88:240-248. [PMID: 29444457 DOI: 10.1016/j.mcn.2018.02.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Revised: 01/22/2018] [Accepted: 02/09/2018] [Indexed: 11/17/2022] Open
Abstract
Astrocytes are a heterogeneous population of glial cells that react to brain insults through a process referred to as astrogliosis. Reactive astrocytes are characterized by an increase in proliferation, size, migration to the injured zone and release of a plethora of chemical mediators such as NGF and BDNF. The aim of this study was to determine whether there are brain region-associated responses of astrocytes to an injury and to the neurotrophins NGF and BDNF. We used the scratch injury model to study the closure of a wound inflicted on a monolayer of astrocytes obtained from cortex, hippocampus or striatum. Our results indicate that the response of astrocytes to a mechanical lesion differ according to brain regions. Astrocytes from the striatum proliferate and repopulate the injury site more rapidly than astrocytes from cortex or hippocampus. We found that the scratch injury induced the upregulation of neurotrophin receptor p75NTR and TrkB.t in astrocytes from all brain regions studied. When astrocytes from all regions were treated with NGF, the neurotrophin induced migration of the astrocytes (assessed in Boyden chambers) and induced wound closure but did not affect proliferation. In contrast, BDNF induced wound closure but only in astrocytes from striatum. Our overall findings show the heterogeneity in astrocyte functions based on their brain region of origin, and how this functional diversity may determine their responses to an injury and to neurotrophins.
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Affiliation(s)
- Andrea Beatriz Cragnolini
- IIByT-UNC CONICET, CEBICEM, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sarsfield 1611, X5016GCA Córdoba, Argentina
| | - Gonzalo Montenegro
- IIByT-UNC CONICET, CEBICEM, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sarsfield 1611, X5016GCA Córdoba, Argentina
| | - Wilma J Friedman
- Department of Biological Sciences, Rutgers University, 225 University Avenue, Newark, N.J. 07102, United States
| | - Daniel Hugo Mascó
- IIByT-UNC CONICET, CEBICEM, Facultad de Ciencias Exactas Físicas y Naturales, Universidad Nacional de Córdoba, Av. Vélez Sarsfield 1611, X5016GCA Córdoba, Argentina.
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88
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Histone acetylation of oligodendrocytes protects against white matter injury induced by inflammation and hypoxia-ischemia through activation of BDNF-TrkB signaling pathway in neonatal rats. Brain Res 2017; 1688:33-46. [PMID: 29155093 DOI: 10.1016/j.brainres.2017.11.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 09/08/2017] [Accepted: 11/06/2017] [Indexed: 02/07/2023]
Abstract
The major pathological damage in encephalopathy of prematurity is white matter injury (WMI). Perinatal hypoxic-ischemia (HI) and inflammation are two major risk factors in the development of WMI. To study the cellular and molecular mechanisms of WMI, we set up a WMI model using lipopolysaccharide-sensitized HI injury in 2-day postnatal rats. Immunofluorescence staining was used to measure the expression of acetylated histone H3 (AH3) in oligodendrocytes, the target cells of WMI; the oligodendrocyte protein markers, NG2, O4, MBP, PLP, and MAG, were detected at different developmental stages. 5-bromo-2'-deoxyuridine (BrdU) was used to detect the proliferation of oligodendrocytes. We found that the expression of AH3 was markedly decreased in oligodendrocytes at 7 days after WMI. The differentiation and maturation of oligodendrocytes were inhibited in the WMI group. After inducing histone acetylation in oligodendrocytes by treatment with sodium butyrate, the inhibition of differentiation and maturation of oligodendrocytes was reversed. Furthermore, we found that these protective effects of histone acetylation were associated with the upregulation of brain-derived neurotrophic factor (BDNF) and its receptor, tyrosine kinase B (TrkB). In conclusion, histone acetylation protects oligodendrocytes from WMI through activation of the BDNF-TrkB signaling pathway in immature brains.
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89
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Ganz J, Shor E, Guo S, Sheinin A, Arie I, Michaelevski I, Pitaru S, Offen D, Levenberg S. Implantation of 3D Constructs Embedded with Oral Mucosa-Derived Cells Induces Functional Recovery in Rats with Complete Spinal Cord Transection. Front Neurosci 2017; 11:589. [PMID: 29163001 PMCID: PMC5671470 DOI: 10.3389/fnins.2017.00589] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 10/06/2017] [Indexed: 12/23/2022] Open
Abstract
Spinal cord injury (SCI), involving damaged axons and glial scar tissue, often culminates in irreversible impairments. Achieving substantial recovery following complete spinal cord transection remains an unmet challenge. Here, we report of implantation of an engineered 3D construct embedded with human oral mucosa stem cells (hOMSC) induced to secrete neuroprotective, immunomodulatory, and axonal elongation-associated factors, in a complete spinal cord transection rat model. Rats implanted with induced tissue engineering constructs regained fine motor control, coordination and walking pattern in sharp contrast to the untreated group that remained paralyzed (42 vs. 0%). Immunofluorescence, CLARITY, MRI, and electrophysiological assessments demonstrated a reconnection bridging the injured area, as well as presence of increased number of myelinated axons, neural precursors, and reduced glial scar tissue in recovered animals treated with the induced cell-embedded constructs. Finally, this construct is made of bio-compatible, clinically approved materials and utilizes a safe and easily extractable cell population. The results warrant further research with regards to the effectiveness of this treatment in addressing spinal cord injury.
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Affiliation(s)
- Javier Ganz
- Department of Human Molecular Genetics and Biochemistry, Felsenstein Medical Research Center, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Erez Shor
- Department of Biomedical Engineering, Technion, Haifa, Israel
| | - Shaowei Guo
- Department of Biomedical Engineering, Technion, Haifa, Israel
| | - Anton Sheinin
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Ina Arie
- Department of Oral Biology, School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Izhak Michaelevski
- Department of Neurobiology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.,Department of Molecular Biology, Faculty of Natural Sciences, Ariel University, Ariel, Israel
| | - Sandu Pitaru
- Department of Oral Biology, School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Daniel Offen
- Department of Human Molecular Genetics and Biochemistry, Felsenstein Medical Research Center, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
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90
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Jukkola P, Gu Y, Lovett-Racke AE, Gu C. Suppression of Inflammatory Demyelinaton and Axon Degeneration through Inhibiting Kv3 Channels. Front Mol Neurosci 2017; 10:344. [PMID: 29123469 PMCID: PMC5662905 DOI: 10.3389/fnmol.2017.00344] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 10/10/2017] [Indexed: 01/19/2023] Open
Abstract
The development of neuroprotective and repair strategies for treating progressive multiple sclerosis (MS) requires new insights into axonal injury. 4-aminopyridine (4-AP), a blocker of voltage-gated K+ (Kv) channels, is used in symptomatic treatment of progressive MS, but the underlying mechanism remains unclear. Here we report that deleting Kv3.1—the channel with the highest 4-AP sensitivity—reduces clinical signs in experimental autoimmune encephalomyelitis (EAE), a mouse model for MS. In Kv3.1 knockout (KO) mice, EAE lesions in sensory and motor tracts of spinal cord were markedly reduced, and radial astroglia were activated with increased expression of brain derived neurotrophic factor (BDNF). Kv3.3/Kv3.1 and activated BDNF receptors were upregulated in demyelinating axons in EAE and MS lesions. In spinal cord myelin coculture, BDNF treatment promoted myelination, and neuronal firing via altering channel expression. Therefore, suppressing Kv3.1 alters neural circuit activity, which may enhance BNDF signaling and hence protect axons from inflammatory insults.
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Affiliation(s)
- Peter Jukkola
- Biomedical Sciences Graduate Program, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
| | - Yuanzheng Gu
- Department of Biological Chemistry and Pharmacology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
| | - Amy E Lovett-Racke
- Department of Microbial Infection and Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
| | - Chen Gu
- Biomedical Sciences Graduate Program, Wexner Medical Center, The Ohio State University, Columbus, OH, United States.,Department of Biological Chemistry and Pharmacology, Wexner Medical Center, The Ohio State University, Columbus, OH, United States
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91
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Gibson EM, Geraghty AC, Monje M. Bad wrap: Myelin and myelin plasticity in health and disease. Dev Neurobiol 2017; 78:123-135. [PMID: 28986960 DOI: 10.1002/dneu.22541] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/31/2017] [Accepted: 10/03/2017] [Indexed: 12/21/2022]
Abstract
Human central nervous system myelin development extends well into the fourth decade of life, and this protracted period underscores the potential for experience to modulate myelination. The concept of myelin plasticity implies adaptability in myelin structure and function in response to experiences during development and beyond. Mounting evidence supports this concept of neuronal activity-regulated changes in myelin-forming cells, including oligodendrocyte precursor cell proliferation, oligodendrogenesis and modulation of myelin microstructure. In healthy individuals, myelin plasticity in associative white matter structures of the brain is implicated in learning and motor function in both rodents and humans. Activity-dependent changes in myelin-forming cells may influence the function of neural networks that depend on the convergence of numerous neural signals on both a temporal and spatial scale. However, dysregulation of myelin plasticity can disadvantageously alter myelin microstructure and result in aberrant circuit function or contribute to pathological cell proliferation. Emerging roles for myelin plasticity in normal neurological function and in disease are discussed. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 78: 123-135, 2018.
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Affiliation(s)
- Erin M Gibson
- Department of Neurology, Stanford University School of Medicine, Stanford, California, 94305
| | - Anna C Geraghty
- Department of Neurology, Stanford University School of Medicine, Stanford, California, 94305
| | - Michelle Monje
- Department of Neurology, Stanford University School of Medicine, Stanford, California, 94305
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92
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PIF* promotes brain re-myelination locally while regulating systemic inflammation- clinically relevant multiple sclerosis M.smegmatis model. Oncotarget 2017; 8:21834-21851. [PMID: 28423529 PMCID: PMC5400627 DOI: 10.18632/oncotarget.15662] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 01/10/2017] [Indexed: 11/25/2022] Open
Abstract
Neurologic disease diagnosis and treatment is challenging. Multiple Sclerosis (MS) is a demyelinating autoimmune disease with few clinical forms and uncertain etiology. Current studies suggest that it is likely caused by infection(s) triggering a systemic immune response resulting in antigen/non-antigen-related autoimmune response in central nervous system (CNS). New therapeutic approaches are needed. Secreted by viable embryos, PreImplantation Factor (PIF) possesses a local and systemic immunity regulatory role. Synthetic PIF (PIF) duplicates endogenous peptide's protective effect in pre-clinical autoimmune and transplantation models. PIF protects against brain hypoxia-ischemia by directly targeting microglia and neurons. In chronic experimental autoimmune encephalitis (EAE) model PIF reverses paralysis while promoting neural repair. Herein we report that PIF directly promotes brain re-myelination and reverses paralysis in relapsing remitting EAE MS model. PIF crosses the blood-brain barrier targeting microglia. Systemically, PIF decreases pro-inflammatory IL23/IL17 cytokines, while preserving CNS-specific T-cell repertoire. Global brain gene analysis revealed that PIF regulates critical Na+/K+/Ca++ ions, amino acid and glucose transport genes expression. Further, PIF modulates oxidative stress, DNA methylation, cell cycle regulation, and protein ubiquitination while regulating multiple genes. In cultured astrocytes, PIF promotes BDNF-myelin synthesis promoter and SLC2A1 (glucose transport) while reducing deleterious E2F5, and HSP90ab1 (oxidative stress) genes expression. In cultured microglia, PIF increases anti-inflammatory IL10 while reducing pro-inflammatory IFNγ expression. Collectively, PIF promotes brain re-myelination and neuroprotection in relapsing remitting EAE MS model. Coupled with ongoing, Fast-Track FDA approved clinical trial, NCT#02239562 (immune disorder), current data supports PIF's translation for neurodegenerative disorders therapy.
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93
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Yoon H, Radulovic M, Walters G, Paulsen AR, Drucker K, Starski P, Wu J, Fairlie DP, Scarisbrick IA. Protease activated receptor 2 controls myelin development, resiliency and repair. Glia 2017; 65:2070-2086. [PMID: 28921694 DOI: 10.1002/glia.23215] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 08/14/2017] [Accepted: 08/16/2017] [Indexed: 12/22/2022]
Abstract
Oligodendrocytes are essential regulators of axonal energy homeostasis and electrical conduction and emerging target cells for restoration of neurological function. Here we investigate the role of protease activated receptor 2 (PAR2), a unique protease activated G protein-coupled receptor, in myelin development and repair using the spinal cord as a model. Results demonstrate that genetic deletion of PAR2 accelerates myelin production, including higher proteolipid protein (PLP) levels in the spinal cord at birth and higher levels of myelin basic protein and thickened myelin sheaths in adulthood. Enhancements in spinal cord myelin with PAR2 loss-of-function were accompanied by increased numbers of Olig2- and CC1-positive oligodendrocytes, as well as in levels of cyclic adenosine monophosphate (cAMP), and extracellular signal related kinase 1/2 (ERK1/2) signaling. Parallel promyelinating effects were observed after blocking PAR2 expression in purified oligodendrocyte cultures, whereas inhibiting adenylate cyclase reversed these effects. Conversely, PAR2 activation reduced PLP expression and this effect was prevented by brain derived neurotrophic factor (BDNF), a promyelinating growth factor that signals through cAMP. PAR2 knockout mice also showed improved myelin resiliency after traumatic spinal cord injury and an accelerated pattern of myelin regeneration after focal demyelination. These findings suggest that PAR2 is an important controller of myelin production and regeneration, both in the developing and adult spinal cord.
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Affiliation(s)
- Hyesook Yoon
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905.,Department of Physiology and Biomedical Engineering, Rochester, Minnesota, 55905
| | - Maja Radulovic
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905.,Neurobiology of Disease Program, Mayo Clinic, Rochester, Minnesota, 55905
| | - Grant Walters
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905
| | - Alex R Paulsen
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905
| | - Kristen Drucker
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905
| | - Phillip Starski
- Neurobiology of Disease Program, Mayo Clinic, Rochester, Minnesota, 55905
| | - Jianmin Wu
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905
| | - David P Fairlie
- ARC Centre of Excellence in Advanced Molecular Imaging, Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland, 4072, Australia
| | - Isobel A Scarisbrick
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, 55905.,Department of Physiology and Biomedical Engineering, Rochester, Minnesota, 55905.,Neurobiology of Disease Program, Mayo Clinic, Rochester, Minnesota, 55905
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94
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Su WS, Wu CH, Chen SF, Yang FY. Transcranial ultrasound stimulation promotes brain-derived neurotrophic factor and reduces apoptosis in a mouse model of traumatic brain injury. Brain Stimul 2017; 10:1032-1041. [PMID: 28939348 DOI: 10.1016/j.brs.2017.09.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 07/31/2017] [Accepted: 09/02/2017] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND The protein expressions of brain-derived neurotrophic factor (BDNF) can be elevated by transcranial ultrasound stimulation in the rat brain. OBJECTIVE The purpose of this study was to investigate the effects and underlying mechanisms of BDNF enhancement by low-intensity pulsed ultrasound (LIPUS) on traumatic brain injury (TBI). METHODS Mice subjected to controlled cortical impact injury were treated with LIPUS in the injured region daily for a period of 4 days. Western blot analysis and immunohistochemistry were performed to assess the effects of LIPUS. RESULTS The results showed that the LIPUS treatment significantly promoted the neurotrophic factors BDNF and vascular endothelial growth factor (VEGF) at day 4 after TBI. Meanwhile, LIPUS also enhanced the phosphorylation of Tropomyosin-related kinase B (TrkB), Akt, and cAMP-response element binding protein (CREB). Furthermore, treatment with LIPUS significantly decreased the level of cleaved caspase-3. The reduction of apoptotic process was inhibited by the anti-BDNF antibody. CONCLUSIONS In short, post-injury LIPUS treatment increased BDNF protein levels and inhibited the progression of apoptosis following TBI. The neuroprotective effects of LIPUS may be associated with enhancements of the protein levels of neurotrophic factors, at least partially via the TrkB/Akt-CREB signaling pathway.
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Affiliation(s)
- Wei-Shen Su
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Chun-Hu Wu
- Graduate Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Szu-Fu Chen
- Departments of Physiology and Biophysics, National Defense Medical Center, Taipei, Taiwan; Department of Physical Medicine and Rehabilitation, Cheng Hsin General Hospital, Taipei, Taiwan.
| | - Feng-Yi Yang
- Department of Biomedical Imaging and Radiological Sciences, National Yang-Ming University, Taipei, Taiwan; Biophotonics and Molecular Imaging Research Center, National Yang-Ming University, Taipei, Taiwan.
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95
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Mousavi Majd A, Ebrahim Tabar F, Afghani A, Ashrafpour S, Dehghan S, Gol M, Ashrafpour M, Pourabdolhossein F. Inhibition of GABA A receptor improved spatial memory impairment in the local model of demyelination in rat hippocampus. Behav Brain Res 2017; 336:111-121. [PMID: 28866129 DOI: 10.1016/j.bbr.2017.08.046] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 08/20/2017] [Accepted: 08/29/2017] [Indexed: 12/15/2022]
Abstract
Cognitive impairment and memory deficit are common features in multiple Sclerosis patients. The mechanism of memory impairment in MS is unknown, but neuroimaging studies suggest that hippocampal demyelination is involved. Here, we investigate the role of GABA A receptor on spatial memory in the local model of hippocampal demyelination. Demyelination was induced in male Wistar rats by bilaterally injection of lysophosphatidylcholine (LPC) 1% into the CA1 region of the hippocampus. The treatment groups were received daily intraventricular injection of bicuculline (0.025, 0.05μg/2μl/animal) or muscimol (0.1, 0.2μg/2μl/animal) 5days after LPC injection. Morris Water Maze was used to evaluate learning and memory in rats. We used Luxol fast blue staining and qPCR to assess demyelination extention and MBP expression level respectively. Immunohistochemistry (IHC) for CD45 and H&E staining were performed to assess inflammatory cells infiltration. Behavioral study revealed that LPC injection in the hippocampus impaired learning and memory function. Animals treated with both doses of bicuculline improved spatial learning and memory function; however, muscimol treatment had no effect. Histological and MBP expression studies confirmed that demylination in LPC group was maximal. Bicuculline treatment significantly reduced demyelination extension and increased the level of MBP expression. H&E and IHC results showed that bicuculline reduced inflammatory cell infiltration in the lesion site. Bicuculline improved learning and memory and decreased demyelination extention in the LPC-induced hippocampal demyelination model. We conclude that disruption of GABAergic homeostasis in hippocampal demyelination context may be involved in memory impairment with the implications for both pathophysiology and therapy.
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Affiliation(s)
- Alireza Mousavi Majd
- Student Research Committee, Babol University of Medical Sciences, Babol, Iran; Neuroscience Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Forough Ebrahim Tabar
- Student Research Committee, Babol University of Medical Sciences, Babol, Iran; Neuroscience Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Arghavan Afghani
- Student Research Committee, Babol University of Medical Sciences, Babol, Iran; Neuroscience Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Sahand Ashrafpour
- Student Research Committee, Babol University of Medical Sciences, Babol, Iran; Neuroscience Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Samaneh Dehghan
- Physiology Departments, Faculty of Medicine, Tarbiat Modares University, Tehran, Iran
| | - Mohammad Gol
- Student Research Committee, Babol University of Medical Sciences, Babol, Iran
| | - Manouchehr Ashrafpour
- Neuroscience Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran; Physiology Departments, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran
| | - Fereshteh Pourabdolhossein
- Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran; Neuroscience Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran; Physiology Departments, Faculty of Medicine, Babol University of Medical Sciences, Babol, Iran.
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96
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Araújo SES, Mendonça HR, Wheeler NA, Campello-Costa P, Jacobs KM, Gomes FCA, Fox MA, Fuss B. Inflammatory demyelination alters subcortical visual circuits. J Neuroinflammation 2017; 14:162. [PMID: 28821276 PMCID: PMC5562979 DOI: 10.1186/s12974-017-0936-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 08/07/2017] [Indexed: 11/13/2022] Open
Abstract
Background Multiple sclerosis (MS) is an inflammatory demyelinating disease classically associated with axonal damage and loss; more recently, however, synaptic changes have been recognized as additional contributing factors. An anatomical area commonly affected in MS is the visual pathway; yet, changes other than those associated with inflammatory demyelination of the optic nerve, i.e., optic neuritis, have not been described in detail. Methods Adult mice were subjected to a diet containing cuprizone to mimic certain aspects of inflammatory demyelination as seen in MS. Demyelination and inflammation were assessed by real-time polymerase chain reaction and immunohistochemistry. Synaptic changes associated with inflammatory demyelination in the dorsal lateral geniculate nucleus (dLGN) were determined by immunohistochemistry, Western blot analysis, and electrophysiological field potential recordings. Results In the cuprizone model, demyelination was observed in retinorecipient regions of the subcortical visual system, in particular the dLGN, where it was found accompanied by microglia activation and astrogliosis. In contrast, anterior parts of the pathway, i.e., the optic nerve and tract, appeared largely unaffected. Under the inflammatory demyelinating conditions, as seen in the dLGN of cuprizone-treated mice, there was an overall decrease in excitatory synaptic inputs from retinal ganglion cells. At the same time, the number of synaptic complexes arising from gamma-aminobutyric acid (GABA)-generating inhibitory neurons was found increased, as were the synapses that contain the N-methyl-d-aspartate receptor (NMDAR) subunit GluN2B and converge onto inhibitory neurons. These synaptic changes were functionally found associated with a shift toward an overall increase in network inhibition. Conclusions Using the cuprizone model of inflammatory demyelination, our data reveal a novel form of synaptic (mal)adaption in the CNS that is characterized by a shift of the excitation/inhibition balance toward inhibitory network activity associated with an increase in GABAergic inhibitory synapses and a possible increase in excitatory input onto inhibitory interneurons. In addition, our data recognize the cuprizone model as a suitable tool in which to assess the effects of inflammatory demyelination on subcortical retinorecipient regions of the visual system, such as the dLGN, in the absence of overt optic neuritis.
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Affiliation(s)
- Sheila Espírito Santo Araújo
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.,Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Instituto de Biologia, Programa de Neurociências, Universidade Federal Fluminense, Niterói, Brazil.,Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Henrique Rocha Mendonça
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.,Instituto de Biologia, Programa de Neurociências, Universidade Federal Fluminense, Niterói, Brazil
| | - Natalie A Wheeler
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Paula Campello-Costa
- Instituto de Biologia, Programa de Neurociências, Universidade Federal Fluminense, Niterói, Brazil
| | - Kimberle M Jacobs
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Flávia C A Gomes
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Michael A Fox
- Developmental and Translational Neurobiology Center, Virginia Tech Carilion Research Institute, Roanoke, VA, USA
| | - Babette Fuss
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
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97
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Mount CW, Monje M. Wrapped to Adapt: Experience-Dependent Myelination. Neuron 2017; 95:743-756. [PMID: 28817797 PMCID: PMC5667660 DOI: 10.1016/j.neuron.2017.07.009] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Revised: 07/05/2017] [Accepted: 07/10/2017] [Indexed: 02/03/2023]
Abstract
Activity of the nervous system has long been recognized as a critical modulator of brain structure and function. Influences of experience on the cytoarchitecture and functional connectivity of neurons have been appreciated since the classic work of Hubel and Wiesel (1963; Wiesel and Hubel, 1963a, 1963b). In recent years, a similar structural plasticity has come to light for the myelinated infrastructure of the nervous system. While an innate program of myelin development proceeds independently of nervous system activity, increasing evidence supports a role for activity-dependent, plastic changes in myelin-forming cells that influence myelin structure and neurological function. Accumulating evidence of complementary and likely temporally overlapping activity-independent and activity-dependent modes of myelination are beginning to crystallize in a model of myelin plasticity, with broad implications for neurological function in health and disease.
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Affiliation(s)
| | - Michelle Monje
- Department of Neurology, Stanford University, Stanford, CA 94305, USA.
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98
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Abstract
Regulated exocytosis can be split into a sequence of steps ending with the formation and the dilation of a fusion pore, a neck-like connection between the vesicle and the plasma membrane. Each of these steps is precisely controlled to achieve the optimal spatial and temporal profile of the release of signalling molecules. At the level of the fusion pore, tuning of the exocytosis can be achieved by preventing its formation, by stabilizing the unproductive narrow fusion pore, by altering the speed of fusion pore expansion and by completely closing the fusion pore. The molecular structure and dynamics of fusion pores have become a major focus of cell research, especially as a promising target for therapeutic strategies. Electrophysiological, optical and electrochemical methods have been used extensively to illuminate how cells regulate secretion at the level of a single fusion pore. Here, we describe recent advances in the structure and mechanisms of the initial fusion pore formation and the progress in therapeutic strategies with the focus on exocytosis.
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99
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Liu Y, Yan Y, Inagaki Y, Logan S, Bosnjak ZJ, Bai X. Insufficient Astrocyte-Derived Brain-Derived Neurotrophic Factor Contributes to Propofol-Induced Neuron Death Through Akt/Glycogen Synthase Kinase 3β/Mitochondrial Fission Pathway. Anesth Analg 2017. [PMID: 28622174 DOI: 10.1213/ane.0000000000002137] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Growing animal evidence demonstrates that prolonged exposure to propofol during brain development induces widespread neuronal cell death, but there is little information on the role of astrocytes. Astrocytes can release neurotrophic growth factors such as brain-derived neurotrophic factor (BDNF), which can exert the protective effect on neurons in paracrine fashion. We hypothesize that during propofol anesthesia, BDNF released from developing astrocytes may not be sufficient to prevent propofol-induced neurotoxicity. METHODS Hippocampal astrocytes and neurons isolated from neonatal Sprague Dawley rats were exposed to propofol at a clinically relevant dose of 30 μM or dimethyl sulfoxide as control for 6 hours. Propofol-induced cell death was determined by propidium iodide (PI) staining in astrocyte-alone cultures, neuron-alone cultures, or cocultures containing either low or high density of astrocytes (1:9 or 1:1 ratio of astrocytes to neurons ratio [ANR], respectively). The astrocyte-conditioned medium was collected 12 hours after propofol exposure and measured by protein array assay. BDNF concentration in astrocyte-conditioned medium was quantified using enzyme-linked immunosorbent assay. Neuron-alone cultures were treated with BDNF, tyrosine receptor kinase B inhibitor cyclotraxin-B, glycogen synthase kinase 3β (GSK3β) inhibitor CHIR99021, or mitochondrial fission inhibitor Mdivi-1 before propofol exposure. Western blot was performed for quantification of the level of protein kinase B and GSK3β. Mitochondrial shape was visualized through translocase of the outer membrane 20 staining. RESULTS Propofol increased cell death in neurons by 1.8-fold (% of PI-positive cells [PI%] = 18.6; 95% confidence interval [CI], 15.2-21.9, P < .05) but did not influence astrocyte viability. The neuronal death was attenuated by a high ANR (1:1 cocultures; fold change [FC] = 1.17, 95% CI, 0.96-1.38, P < .05), but not with a low ANR [1:9 cocultures; FC = 1.87, 95% CI, 1.48-2.26, P > .05]). Astrocytes secreted BDNF in a cell density-dependent way and propofol decreased BDNF secretion from astrocytes. Administration of BDNF, CHIR99021, or Mdivi-1 significantly attenuated the propofol-induced neuronal death and aberrant mitochondria in neuron-alone cultures (FC = 0.8, 95% CI, 0.62-0.98; FC = 1.22, 95% CI, 1.11-1.32; FC = 1.35, 95% CI, 1.16-1.54, respectively, P < .05) and the cocultures with a low ANR (1:9; FC = 0.85, 95% CI, 0.74-0.97; FC = 1.08, 95% CI, 0.84-1.32; FC = 1.25, 95% CI, 1.1-1.39, respectively, P < .05). Blocking BDNF receptor or protein kinase B activity abolished astrocyte-induced neuroprotection in the cocultures with a high ANR (1:1). CONCLUSIONS Astrocytes attenuate propofol-induced neurotoxicity through BDNF-mediated cell survival pathway suggesting multiple neuroprotective strategies such as administration of BDNF, astrocyte-conditioned medium, decreasing mitochondrial fission, or inhibition of GSK3β.
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Affiliation(s)
- Yanan Liu
- From the Departments of *Anesthesiology and †Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
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Yoon H, Walters G, Paulsen AR, Scarisbrick IA. Astrocyte heterogeneity across the brain and spinal cord occurs developmentally, in adulthood and in response to demyelination. PLoS One 2017; 12:e0180697. [PMID: 28700615 PMCID: PMC5507262 DOI: 10.1371/journal.pone.0180697] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 06/20/2017] [Indexed: 01/08/2023] Open
Abstract
Astrocytes have emerged as essential regulators of function and response to injury in the brain and spinal cord, yet very little is known about regional differences that exist. Here we compare the expression of key astroglial markers (glial fibrillary acidic protein (GFAP) and Aldehyde Dehydrogenase-1 Family Member L1 (ALDH1L1)) across these disparate poles of the neuraxis, tracking their expression developmentally and in the context of demyelination. In addition, we document changes in the astrocyte regulatory cytokine interleukin 6 (IL-6), and its signaling partner signal transducer and activator of transcription 3 (STAT3), in vivo and in vitro. Results demonstrate that GFAP expression is higher in the developing and adult spinal cord relative to brain. Comparisons between GFAP and ALDH1L1 expression suggest elevations in spinal cord GFAP during the early postnatal period reflect an accelerated appearance of astrocytes, while elevations in adulthood reflect higher expression by individual astrocytes. Notably, increases in spinal cord compared to whole brain GFAP were paralleled by higher levels of IL-6 and STAT3. Equivalent elevations in GFAP, GFAP/ALDH1L1 ratios, and in IL-6, were observed in primary astrocyte cultures derived from spinal cord compared to cortex. Also, higher levels of GFAP were observed in the spinal cord compared to the brain after focal demyelinating injury. Altogether, these studies point to key differences in astrocyte abundance and the expression of GFAP and IL-6 across the brain and spinal cord that are positioned to influence regional specialization developmentally and responses occurring in the context of injury and disease.
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Affiliation(s)
- Hyesook Yoon
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Grant Walters
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Alex R. Paulsen
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States of America
| | - Isobel A. Scarisbrick
- Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Mayo Clinic, Rochester, Minnesota, United States of America
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States of America
- Neurobiology of Disease Program, Mayo Clinic, Rochester, Minnesota, United States of America
- * E-mail:
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