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Meinhardt J, Streit S, Dittmayer C, Manitius RV, Radbruch H, Heppner FL. The neurobiology of SARS-CoV-2 infection. Nat Rev Neurosci 2024; 25:30-42. [PMID: 38049610 DOI: 10.1038/s41583-023-00769-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/01/2023] [Indexed: 12/06/2023]
Abstract
Worldwide, over 694 million people have been infected with SARS-CoV-2, with an estimated 55-60% of those infected developing COVID-19. Since the beginning of the pandemic in December 2019, different variants of concern have appeared and continue to occur. With the emergence of different variants, an increasing rate of vaccination and previous infections, the acute neurological symptomatology of COVID-19 changed. Moreover, 10-45% of individuals with a history of SARS-CoV-2 infection experience symptoms even 3 months after disease onset, a condition that has been defined as 'post-COVID-19' by the World Health Organization and that occurs independently of the virus variant. The pathomechanisms of COVID-19-related neurological complaints have become clearer during the past 3 years. To date, there is no overt - that is, truly convincing - evidence for SARS-CoV-2 particles in the brain. In this Review, we put special emphasis on discussing the methodological difficulties of viral detection in CNS tissue and discuss immune-based (systemic and central) effects contributing to COVID-19-related CNS affection. We sequentially review the reported changes to CNS cells in COVID-19, starting with the blood-brain barrier and blood-cerebrospinal fluid barrier - as systemic factors from the periphery appear to primarily influence barriers and conduits - before we describe changes in brain parenchymal cells, including microglia, astrocytes, neurons and oligodendrocytes as well as cerebral lymphocytes. These findings are critical to understanding CNS affection in acute COVID-19 and post-COVID-19 in order to translate these findings into treatment options, which are still very limited.
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Affiliation(s)
- Jenny Meinhardt
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Simon Streit
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Carsten Dittmayer
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Regina V Manitius
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany
| | - Helena Radbruch
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany.
| | - Frank L Heppner
- Department of Neuropathology, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Berlin, Germany.
- Cluster of Excellence, NeuroCure, Berlin, Germany.
- German Center for Neurodegenerative Diseases (DZNE) Berlin, Berlin, Germany.
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2
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Thapa M, Kumari A, Chin CY, Choby JE, Jin F, Bogati B, Chopyk DM, Koduri N, Pahnke A, Elrod EJ, Burd EM, Weiss DS, Grakoui A. Translocation of gut commensal bacteria to the brain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.30.555630. [PMID: 37693595 PMCID: PMC10491268 DOI: 10.1101/2023.08.30.555630] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
The gut-brain axis, a bidirectional signaling network between the intestine and the central nervous system, is crucial to the regulation of host physiology and inflammation. Recent advances suggest a strong correlation between gut dysbiosis and neurological diseases, however, relatively little is known about how gut bacteria impact the brain. Here, we reveal that gut commensal bacteria can translocate directly to the brain when mice are fed an altered diet that causes dysbiosis and intestinal permeability, and that this also occurs without diet alteration in distinct murine models of neurological disease. The bacteria were not found in other systemic sites or the blood, but were detected in the vagus nerve. Unilateral cervical vagotomy significantly reduced the number of bacteria in the brain, implicating the vagus nerve as a conduit for translocation. The presence of bacteria in the brain correlated with microglial activation, a marker of neuroinflammation, and with neural protein aggregation, a hallmark of several neurodegenerative diseases. In at least one model, the presence of bacteria in the brain was reversible as a switch from high-fat to standard diet resulted in amelioration of intestinal permeability, led to a gradual loss of detectable bacteria in the brain, and reduced the number of neural protein aggregates. Further, in murine models of Alzheimer's disease, Parkinson's disease, and autism spectrum disorder, we observed gut dysbiosis, gut leakiness, bacterial translocation to the brain, and microglial activation. These data reveal a commensal bacterial translocation axis to the brain in models of diverse neurological diseases.
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Affiliation(s)
- Manoj Thapa
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
| | - Anuradha Kumari
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
| | - Chui-Yoke Chin
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
| | - Jacob E. Choby
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
| | - Fengzhi Jin
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
| | - Bikash Bogati
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
| | - Daniel M. Chopyk
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
| | - Nitya Koduri
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
| | - Andrew Pahnke
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
| | - Elizabeth J. Elrod
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
| | - Eileen M. Burd
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
- Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia
- Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia
| | - David S. Weiss
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
- Emory Antibiotic Resistance Center, Emory University School of Medicine, Atlanta, Georgia
| | - Arash Grakoui
- Emory Vaccine Center, Division of Microbiology and Immunology, Emory National Primate Research Center, Emory University, Atlanta, Georgia
- Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
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3
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Zhang T, Pang W, Feng T, Guo J, Wu K, Nunez Santos M, Arthanarisami A, Nana AL, Nguyen Q, Kim PJ, Jankowsky JL, Seeley WW, Hu F. TMEM106B regulates microglial proliferation and survival in response to demyelination. SCIENCE ADVANCES 2023; 9:eadd2676. [PMID: 37146150 PMCID: PMC10162677 DOI: 10.1126/sciadv.add2676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 04/05/2023] [Indexed: 05/07/2023]
Abstract
TMEM106B, a lysosomal transmembrane protein, has been closely associated with brain health. Recently, an intriguing link between TMEM106B and brain inflammation has been discovered, but how TMEM106B regulates inflammation is unknown. Here, we report that TMEM106B deficiency in mice leads to reduced microglia proliferation and activation and increased microglial apoptosis in response to demyelination. We also found an increase in lysosomal pH and a decrease in lysosomal enzyme activities in TMEM106B-deficient microglia. Furthermore, TMEM106B loss results in a significant decrease in the protein levels of TREM2, an innate immune receptor essential for microglia survival and activation. Specific ablation of TMEM106B in microglia results in similar microglial phenotypes and myelination defects in mice, supporting the idea that microglial TMEM106B is critical for proper microglial activities and myelination. Moreover, the TMEM106B risk allele is associated with myelin loss and decreased microglial numbers in humans. Collectively, our study unveils a previously unknown role of TMEM106B in promoting microglial functionality during demyelination.
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Affiliation(s)
- Tingting Zhang
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Weilun Pang
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Tuancheng Feng
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Jennifer Guo
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Kenton Wu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Mariela Nunez Santos
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Akshayakeerthi Arthanarisami
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Alissa L. Nana
- Department of Neurology, University of California, San Francisco, CA 94158, USA
| | - Quynh Nguyen
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
| | - Peter J. Kim
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
| | - Joanna L. Jankowsky
- Department of Neuroscience, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
- Departments of Molecular and Cellular Biology, Neurology, and Neurosurgery, Huffington Center on Aging, Baylor College of Medicine, Houston, TX, USA
| | - William W. Seeley
- Department of Neurology, University of California, San Francisco, CA 94158, USA
- Department of Pathology, University of California, San Francisco, CA 94158, USA
| | - Fenghua Hu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
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Zhang T, Feng T, Wu K, Guo J, Nana AL, Yang G, Seeley WW, Hu F. Progranulin deficiency results in sex-dependent alterations in microglia in response to demyelination. Acta Neuropathol 2023:10.1007/s00401-023-02578-w. [PMID: 37120788 PMCID: PMC10375542 DOI: 10.1007/s00401-023-02578-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 04/17/2023] [Accepted: 04/18/2023] [Indexed: 05/01/2023]
Abstract
Heterozygous mutations in the granulin (GRN) gene, resulting in the haploinsufficiency of the progranulin (PGRN) protein, is a leading cause of frontotemporal lobar degeneration (FTLD). Complete loss of the PGRN protein causes neuronal ceroid lipofuscinosis (NCL), a lysosomal storage disorder. Polymorphisms in the GRN gene have also been associated with several other neurodegenerative diseases, including Alzheimer's disease (AD), and Parkinson's disease (PD). PGRN deficiency has been shown to cause myelination defects previously, but how PGRN regulates myelination is unknown. Here, we report that PGRN deficiency leads to a sex-dependent myelination defect with male mice showing more severe demyelination in response to cuprizone treatment. This is accompanied by exacerbated microglial proliferation and activation in the male PGRN-deficient mice. Interestingly, both male and female PGRN-deficient mice show sustained microglial activation after cuprizone removal and a defect in remyelination. Specific ablation of PGRN in microglia results in similar sex-dependent phenotypes, confirming a microglial function of PGRN. Lipid droplets accumulate in microglia specifically in male PGRN-deficient mice. RNA-seq analysis and mitochondrial function assays reveal key differences in oxidative phosphorylation in male versus female microglia under PGRN deficiency. A significant decrease in myelination and accumulation of myelin debris and lipid droplets in microglia were found in the corpus callosum regions of FTLD patients with GRN mutations. Taken together, our data support that PGRN deficiency leads to sex-dependent alterations in microglia with subsequent myelination defects.
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Affiliation(s)
- Tingting Zhang
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY, 14853, USA
| | - Tuancheng Feng
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY, 14853, USA
| | - Kenton Wu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY, 14853, USA
| | - Jennifer Guo
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY, 14853, USA
| | - Alissa L Nana
- Department of Neurology, University of California, San Francisco, CA, 94158, USA
| | - Guang Yang
- Department of Anesthesiology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - William W Seeley
- Department of Neurology, University of California, San Francisco, CA, 94158, USA
- Department of Pathology, University of California, San Francisco, CA, 94158, USA
| | - Fenghua Hu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, 345 Weill Hall, Ithaca, NY, 14853, USA.
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La Torre ME, Villano I, Monda M, Messina A, Cibelli G, Valenzano A, Pisanelli D, Panaro MA, Tartaglia N, Ambrosi A, Carotenuto M, Monda V, Messina G, Porro C. Role of Vitamin E and the Orexin System in Neuroprotection. Brain Sci 2021; 11:brainsci11081098. [PMID: 34439717 PMCID: PMC8394512 DOI: 10.3390/brainsci11081098] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/13/2021] [Accepted: 08/16/2021] [Indexed: 12/24/2022] Open
Abstract
Microglia are the first line of defense at the level of the central nervous system (CNS). Phenotypic change in microglia can be regulated by various factors, including the orexin system. Neuroinflammation is an inflammatory process mediated by cytokines, by the lack of interaction between neurotransmitters and their specific receptors, caused by systemic tissue damage or, more often, associated with direct damage to the CNS. Chronic activation of microglia could lead to long-term neurodegenerative diseases. This review aims to explore how tocopherol (vitamin E) and the orexin system may play a role in the prevention and treatment of microglia inflammation and, consequently, in neurodegenerative diseases thanks to its antioxidant properties. The results of animal and in vitro studies provide evidence to support the use of tocopherol for a reduction in microglia inflammation as well as a greater activation of the orexinergic system. Although there is much in vivo and in vitro evidence of vitamin E antioxidant and protective abilities, there are still conflicting results for its use as a treatment for neurodegenerative diseases that speculate that vitamin E, under certain conditions or genetic predispositions, can be pro-oxidant and harmful.
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Affiliation(s)
- Maria Ester La Torre
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy; (M.E.L.T.); (G.C.); (A.V.); (D.P.); (C.P.)
| | - Ines Villano
- Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetics and Sports Medicine, Università degli Studi della Campania “Luigi Vanvitelli”, 80100 Naples, Italy; (I.V.); (M.M.); (A.M.); (V.M.)
| | - Marcellino Monda
- Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetics and Sports Medicine, Università degli Studi della Campania “Luigi Vanvitelli”, 80100 Naples, Italy; (I.V.); (M.M.); (A.M.); (V.M.)
| | - Antonietta Messina
- Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetics and Sports Medicine, Università degli Studi della Campania “Luigi Vanvitelli”, 80100 Naples, Italy; (I.V.); (M.M.); (A.M.); (V.M.)
| | - Giuseppe Cibelli
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy; (M.E.L.T.); (G.C.); (A.V.); (D.P.); (C.P.)
| | - Anna Valenzano
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy; (M.E.L.T.); (G.C.); (A.V.); (D.P.); (C.P.)
| | - Daniela Pisanelli
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy; (M.E.L.T.); (G.C.); (A.V.); (D.P.); (C.P.)
| | - Maria Antonietta Panaro
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, 70125 Bari, Italy;
| | - Nicola Tartaglia
- Department of Medical and Surgical Sciences, University of Foggia, Viale Pinto, 71122 Foggia, Italy; (N.T.); (A.A.)
| | - Antonio Ambrosi
- Department of Medical and Surgical Sciences, University of Foggia, Viale Pinto, 71122 Foggia, Italy; (N.T.); (A.A.)
| | - Marco Carotenuto
- Clinic of Child and Adolescent Neuropsychiatry, Department of Mental Health, Physical and Preventive Medicine, Università degli Studi della Campania “Luigi Vanvitelli”, 80100 Naples, Italy;
| | - Vincenzo Monda
- Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetics and Sports Medicine, Università degli Studi della Campania “Luigi Vanvitelli”, 80100 Naples, Italy; (I.V.); (M.M.); (A.M.); (V.M.)
| | - Giovanni Messina
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy; (M.E.L.T.); (G.C.); (A.V.); (D.P.); (C.P.)
- Correspondence: ; Tel.: +39-8815-88095
| | - Chiara Porro
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy; (M.E.L.T.); (G.C.); (A.V.); (D.P.); (C.P.)
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Kogel V, Trinh S, Gasterich N, Beyer C, Seitz J. Long-Term Glucose Starvation Induces Inflammatory Responses and Phenotype Switch in Primary Cortical Rat Astrocytes. J Mol Neurosci 2021; 71:2368-2382. [PMID: 33580474 PMCID: PMC8585803 DOI: 10.1007/s12031-021-01800-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 01/15/2021] [Indexed: 12/18/2022]
Abstract
Astrocytes are the most abundant cell type in the brain and crucial to ensure the metabolic supply of neurons and their synapse formation. Overnutrition as present in patients suffering from obesity causes astrogliosis in the hypothalamus. Other diseases accompanied by malnutrition appear to have an impact on the brain and astrocyte function. In the eating disorder anorexia nervosa (AN), patients suffer from undernutrition and develop volume reductions of the cerebral cortex, associated with reduced astrocyte proliferation and cell count. Although an effect on astrocytes and their function has already been shown for overnutrition, their role in long-term undernutrition remains unclear. The present study used primary rat cerebral cortex astrocytes to investigate their response to chronic glucose starvation. Cells were grown with a medium containing a reduced glucose concentration (2 mM) for 15 days. Long-term glucose starvation increased the expression of a subset of pro-inflammatory genes and shifted the primary astrocyte population to the pro-inflammatory A1-like phenotype. Moreover, genes encoding for proteins involved in the unfolded protein response were elevated. Our findings demonstrate that astrocytes under chronic glucose starvation respond with an inflammatory reaction. With respect to the multiple functions of astrocytes, an association between elevated inflammatory responses due to chronic starvation and alterations found in the brain of patients suffering from undernutrition seems possible.
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Affiliation(s)
- Vanessa Kogel
- Institute of Neuroanatomy, RWTH Aachen University, 52074, Aachen, Germany.
| | - Stefanie Trinh
- Institute of Neuroanatomy, RWTH Aachen University, 52074, Aachen, Germany
| | - Natalie Gasterich
- Institute of Neuroanatomy, RWTH Aachen University, 52074, Aachen, Germany
| | - Cordian Beyer
- Institute of Neuroanatomy, RWTH Aachen University, 52074, Aachen, Germany
| | - Jochen Seitz
- Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital, RWTH Aachen University, 52074, Aachen, Germany
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Protective Role of Natural and Semi-Synthetic Tocopherols on TNFα-Induced ROS Production and ICAM-1 and Cl-2 Expression in HT29 Intestinal Epithelial Cells. Antioxidants (Basel) 2021; 10:antiox10020160. [PMID: 33499140 PMCID: PMC7911239 DOI: 10.3390/antiox10020160] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/31/2020] [Accepted: 01/19/2021] [Indexed: 12/12/2022] Open
Abstract
Vitamin E, a fat-soluble compound, possesses both antioxidant and non-antioxidant properties. In this study we evaluated, in intestinal HT29 cells, the role of natural tocopherols, α-Toc and δ-Toc, and two semi-synthetic derivatives, namely bis-δ-Toc sulfide (δ-Toc)2S and bis-δ-Toc disulfide (δ-Toc)2S2, on TNFα-induced oxidative stress, and intercellular adhesion molecule-1 (ICAM-1) and claudin-2 (Cl-2) expression. The role of tocopherols was compared to that of N-acetylcysteine (NAC), an antioxidant precursor of glutathione synthesis. The results show that all tocopherol containing derivatives used, prevented TNFα-induced oxidative stress and the increase of ICAM-1 and Cl-2 expression, and that (δ-Toc)2S and (δ-Toc)2S2 are more effective than δ-Toc and α-Toc. The beneficial effects demonstrated were due to tocopherol antioxidant properties, but suppression of TNFα-induced Cl-2 expression seems not only to be related with antioxidant ability. Indeed, while ICAM-1 expression is strongly related to the intracellular redox state, Cl-2 expression is TNFα-up-regulated by both redox and non-redox dependent mechanisms. Since ICAM-1 and Cl-2 increase intestinal bowel diseases, and cause excessive recruitment of immune cells and alteration of the intestinal barrier, natural and, above all, semi-synthetic tocopherols may have a potential role as a therapeutic support against intestinal chronic inflammation, in which TNFα represents an important proinflammatory mediator.
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de Leeuw FA, Schneider JA, Agrawal S, Leurgans SE, Morris MC. Brain tocopherol levels are associated with lower activated microglia density in elderly human cortex. ALZHEIMER'S & DEMENTIA (NEW YORK, N. Y.) 2020; 6:e12021. [PMID: 32864412 PMCID: PMC7444784 DOI: 10.1002/trc2.12021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 02/17/2020] [Indexed: 11/24/2022]
Abstract
INTRODUCTION Higher brain tocopherol levels have been associated with lower levels of Alzheimer's disease (AD) neuropathology; however, the underlying mechanisms are unclear. METHODS We studied the relations of α- and γ-tocopherol brain levels to microglia density in 113 deceased participants from the Memory and Aging Project. We used linear regression analyses to examine associations between tocopherol levels and microglia densities in a basic model adjusted for age, sex, education, apolipoprotein E (APOE)ε4 genotype (any ε4 allele vs. none) , and post-mortem time interval, and a second model additionally adjusted for total amyloid load and neurofibrillary tangle severity. RESULTS Higher α- and γ-tocopherol levels were associated with lower total and activated microglia density in cortical but not in subcortical brain regions. The association between cortical α-tocopherol and total microglia density remained statistically significant after adjusting for AD neuropathology. DISCUSSION These results suggest that the relation between tocopherols and AD might be partly explained by the alleviating effects of tocopherols on microglia activation.
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Affiliation(s)
- Francisca A. de Leeuw
- Alzheimer Center AmsterdamDepartment of NeurologyAmsterdam NeuroscienceVrije Universiteit AmsterdamAmsterdam UMCAmsterdamThe Netherlands
| | - Julie A. Schneider
- Rush Alzheimer's Disease CenterDepartment of Neurological Sciences and Department of Pathology (Neuropathology)Rush University Medical CenterChicagoIllinois
| | - Sonal Agrawal
- Rush Alzheimer's Disease CenterDepartment of Pathology (Neuropathology)Rush University Medical CenterChicagoIllinois
| | - Sue E. Leurgans
- Rush Alzheimer's Disease Center and Department of Neurological SciencesRush University Medical CenterChicagoIllinois
| | - Martha Clare Morris
- Rush Institute for Healthy AgingRush University Medical CenterChicagoIllinois
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Lewen A, Ta TT, Cesetti T, Hollnagel JO, Papageorgiou IE, Chausse B, Kann O. Neuronal gamma oscillations and activity-dependent potassium transients remain regular after depletion of microglia in postnatal cortex tissue. J Neurosci Res 2020; 98:1953-1967. [PMID: 32638411 DOI: 10.1002/jnr.24689] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 06/09/2020] [Accepted: 06/12/2020] [Indexed: 12/28/2022]
Abstract
Microglial cells (resident macrophages) feature rapid activation in CNS disease and can acquire multiple phenotypes exerting neuroprotection or neurotoxicity. The functional impact of surveying ("resting") microglia on neural excitability and neurotransmission in physiology is widely unknown, however. We addressed this issue in male rat hippocampal slice cultures (in situ) by pharmacological microglial ablation within days and by characterizing neuronal gamma-band oscillations (30-70 Hz) that are highly sensitive to neuromodulators and disturbances in ion and energy regulation. Gamma oscillations support action potential timing and synaptic plasticity, associate with higher brain functions like perception and memory, and require precise communication between excitatory pyramidal cells and inhibitory (GABAergic) interneurons. The slice cultures featured well-preserved hippocampal cytoarchitecture and parvalbumin-positive interneuron networks, microglia with ramified morphology, and low basal levels of IL-6, TNF-α, and nitric oxide (NO). Stimulation of slice cultures with the pro-inflammatory cytokine IFN-γ or bacterial LPS serving as positive controls for microglial reactivity induced MHC-II expression and increased cytokine and NO release. Chronic exposure of slice cultures to liposome-encapsulated clodronate reduced the microglial cell population by about 96%, whereas neuronal structures, astrocyte GFAP expression, and basal levels of cytokines and NO were unchanged. Notably, the properties of gamma oscillations reflecting frequency, number and synchronization of synapse activity were regular after microglial depletion. Also, electrical stimulus-induced transients of the extracellular potassium concentration ([K+ ]o ) reflecting cellular K+ efflux, clearance and buffering were unchanged. This suggests that nonreactive microglia are dispensable for neuronal homeostasis and neuromodulation underlying network signaling and rhythm generation in cortical tissue.
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Affiliation(s)
- Andrea Lewen
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Thuy-Truc Ta
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Tiziana Cesetti
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Jan-Oliver Hollnagel
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Ismini E Papageorgiou
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Bruno Chausse
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Oliver Kann
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany.,Interdisciplinary Center for Neurosciences (IZN), University of Heidelberg, Heidelberg, Germany
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A rapid and accurate method to quantify neurite outgrowth from cell and tissue cultures: Two image analytic approaches using adaptive thresholds or machine learning. J Neurosci Methods 2019; 331:108522. [PMID: 31734324 DOI: 10.1016/j.jneumeth.2019.108522] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Revised: 10/23/2019] [Accepted: 11/13/2019] [Indexed: 11/23/2022]
Abstract
BACKGROUND Assessments of axonal outgrowth and dendritic development are essential readouts in many in vitro models in the field of neuroscience. Available analysis software is based on the assessment of fixed immunolabelled tissue samples, making it impossible to follow the dynamic development of neurite outgrowth. Thus, automated algorithms that efficiently analyse brightfield images, such as those obtained during time-lapse microscopy, are needed. NEW METHOD We developed and validated algorithms to quantitatively assess neurite outgrowth from living and unstained spinal cord slice cultures (SCSCs) and dorsal root ganglion cultures (DRGCs) based on an adaptive thresholding approach called NeuriteSegmantation. We used a machine learning approach to evaluate dendritic development from dissociate neuron cultures. RESULTS NeuriteSegmentation successfully recognized axons in brightfield images of SCSCs and DRGCs. The temporal pattern of axonal growth was successfully assessed. In dissociate neuron cultures the total number of cells and their outgrowth of dendrites were successfully assessed using machine learning. COMPARISON WITH EXISTING METHODS The methods were positively correlated and were more time-saving than manual counts, having performing times varying from 0.5-2 min. In addition, NeuriteSegmentation was compared to NeuriteJ®, that uses global thresholding, being more reliable in recognizing axons in areas of intense background. CONCLUSION The developed image analysis methods were more time-saving and user-independent than established approaches. Moreover, by using adaptive thresholding, we could assess images with large variations in background intensity. These tools may prove valuable in the quantitative analysis of axonal and dendritic outgrowth from numerous in vitro models used in neuroscience.
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Age-Related Decrease in Tyrosine Hydroxylase Immunoreactivity in the Substantia Nigra and Region-Specific Changes in Microglia Morphology in HIV-1 Tg Rats. Neurotox Res 2019; 36:563-582. [PMID: 31286433 DOI: 10.1007/s12640-019-00077-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/28/2019] [Accepted: 06/14/2019] [Indexed: 12/12/2022]
Abstract
Animal models have been used to study cellular processes related to human immunodeficiency virus-1 (HIV-1)-associated neurocognitive disorders (HAND). The HIV-1 transgenic (Tg) rat expresses HIV viral genes except the gag-pol replication genes and exhibits neuropathological features similar to HIV patients receiving combined antiretroviral therapy (cART). Using this rat, alterations in dopaminergic function have been demonstrated; however, the data for neuroinflammation and glial reactivity is conflicting. Differences in behavior, tyrosine hydroxylase (TH) immunoreactivity, neuroinflammation, and glia reactivity were assessed in HIV-1 Tg male rats. At 6 and 12 weeks of age, rotarod performance was diminished, motor activity was not altered, and active avoidance latency performance and memory were diminished in HIV-1 Tg rats. TH+ immunoreactivity in the substantia nigra (SN) was decreased at 8 months but not at 2-5 months. At 5 months, astrocyte and microglia morphology was not altered in the cortex, hippocampus, or SN. In the striatum, astrocytes were unaltered, microglia displayed slightly thickened proximal processes, mRNA levels for Iba1 and Cd11b were elevated, and interleukin (Il)1α,Cxcr3, and cell adhesion molecule, Icam, decreased. In the hippocampus, mRNA levels for Tnfa and Cd11b were slightly elevated. No changes were observed in the cortex or SN. The data support an age-related effect of HIV proteins upon the nigrostriatal dopaminergic system and suggest an early response of microglia in the terminal synaptic region with little evidence of an associated neuroinflammatory response across brain regions.
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Cebulla CM, Kim B, George V, Heisler-Taylor T, Hamadmad S, Reese AY, Kothari SS, Kusibati R, Wilson H, Abdel-Rahman MH. Oral Selumetinib Does Not Negatively Impact Photoreceptor Survival in Murine Experimental Retinal Detachment. Invest Ophthalmol Vis Sci 2019; 60:349-357. [PMID: 30682205 PMCID: PMC6348998 DOI: 10.1167/iovs.18-25405] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Purpose Mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) signaling is neuroprotective in some retinal damage models but its role in neuronal survival during retinal detachment (RD) is unclear. In addition, serous RDs are a prevalent side effect of MEK inhibitors (MEKi), blocking MAPK/ERK signaling for treatment of certain cancers. We tested the hypothesis that MEKi treatment in experimental RD would increase photoreceptor death. Methods The MEKi selumetinib was delivered daily to C57BL/6 mice at a clinically relevant dose (10 mg/mL) starting 1 day prior to creating RD with subretinal hyaluronic acid injection. Photoreceptor TUNEL and outer nuclear layer (ONL) thickness were analyzed. Phospho-ERK1/2 (pERK) distribution, glial fibrillary acidic protein (GFAP) accumulation, and Iba-1 (microglia/macrophages) were evaluated with immunofluorescence. Results pERK accumulated in the Müller glia in detached retinas, but this was effectively blocked by selumetinib. Selumetinib did not induce serous RDs at day 1 and did not increase TUNEL positive photoreceptors or further decrease ONL thickness compared to controls. Retinal gliosis was not altered, but selumetinib did block the increase in intraretinal microglia/macrophage Iba-1 fluorescence intensity and acquisition of amoeboid morphology. Conclusions MAPK/ERK is neuroprotective in some retinal damage models; in RD, selumetinib blocked Müller pERK accumulation and changed the retinal microglia/macrophage phenotype but did not alter photoreceptor survival. This is consistent with the relatively good visual acuity seen in patients developing transient retinal detachments on MEK inhibitor therapy. Compensation by other neuroprotective pathways in the retina during retinal detachment may occur in the presence of MEK inhibition.
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Affiliation(s)
- Colleen M Cebulla
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
| | - Bongsu Kim
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
| | - Valerie George
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
| | - Tyler Heisler-Taylor
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States.,Department of Biomedical Engineering, The Ohio State University College of Engineering, Columbus, Ohio, United States
| | - Sumaya Hamadmad
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
| | - Alana Y Reese
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
| | - Shaili S Kothari
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
| | - Rania Kusibati
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
| | - Hailey Wilson
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
| | - Mohamed H Abdel-Rahman
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States.,Division of Human Genetics, Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States
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Hohmann T, Feese K, Ghadban C, Dehghani F, Grabiec U. On the influence of cannabinoids on cell morphology and motility of glioblastoma cells. PLoS One 2019; 14:e0212037. [PMID: 30753211 PMCID: PMC6372232 DOI: 10.1371/journal.pone.0212037] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 01/25/2019] [Indexed: 12/20/2022] Open
Abstract
The mechanisms behind the anti-tumoral effects of cannabinoids by impacting the migratory activity of tumor cells are only partially understood. Previous studies demonstrated that cannabinoids altered the organization of the actin cytoskeleton in various cell types. As actin is one of the main contributors to cell motility and is postulated to be linked to tumor invasion, we tested the following hypothesizes: 1) Can cannabinoids alter cell motility in a cannabinoid receptor dependent manner? 2) Are these alterations associated with reorganizations in the actin cytoskeleton? 3) If so, what are the underlying molecular mechanisms? Three different glioblastoma cell lines were treated with specific cannabinoid receptor 1 and 2 agonists and antagonists. Afterwards, we measured changes in cell motility using live cell imaging and alterations of the actin structure in fixed cells. Additionally, the protein amount of phosphorylated p44/42 mitogen-activated protein kinase (MAPK), focal adhesion kinases (FAK) and phosphorylated FAK (pFAK) over time were measured. Cannabinoids induced changes in cell motility, morphology and actin organization in a receptor and cell line dependent manner. No significant changes were observed in the analyzed signaling molecules. Cannabinoids can principally induce changes in the actin cytoskeleton and motility of glioblastoma cell lines. Additionally, single cell motility of glioblastoma is independent of their morphology. Furthermore, the observed effects seem to be independent of p44/42 MAPK and pFAK pathways.
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Affiliation(s)
- Tim Hohmann
- Institute of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Kerstin Feese
- Institute of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Chalid Ghadban
- Institute of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Faramarz Dehghani
- Institute of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Urszula Grabiec
- Institute of Anatomy and Cell Biology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
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14
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Yang C, Wang L, Weng W, Wang S, Ma Y, Mao Q, Gao G, Chen R, Feng J. Steered migration and changed morphology of human astrocytes by an applied electric field. Exp Cell Res 2018; 374:282-289. [PMID: 30508512 DOI: 10.1016/j.yexcr.2018.11.029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 11/27/2018] [Accepted: 11/29/2018] [Indexed: 01/01/2023]
Abstract
Direct current electric field (DC EF) plays a role in influencing the biological behaviors and functions of cells. We hypothesize that human astrocytes (HAs) could also be influenced in EF. Astrocytes, an important type of nerve cells with a high proportion quantitatively, are generally activated and largely decide the brain repair results after brain injury. So far, no electrotaxis study on HAs has been performed. We here obtained HAs derived from brain trauma patients. After purification and identification, HAs were seeded in the EF chamber and recorded in a time-lapse image system. LY294002 and U0126 were then used to probe the role of PI3K or ERK signaling pathway on cellular behaviors. The results showed that HAs could be guided to migrate to the anode in DC EFs, in a voltage-dependent manner. The HAs displayed elongated cell bodies and reoriented perpendicularly to the EF in morphology. When treated with LY294002 or U0126, alternation of parameters such as cellular verticality, track speed, displacement speed, long axis, vertical length and circularity were inhibited partly as expected, while the EF-induced directedness was not terminated even at a high drug dosage which was not consistent with previous electrotaxis studies. In conclusion, applied EFs steered the patient-derived HAs directional migration and changed morphology, in which PI3K and ERK pathways at least partially participate. The characteristics of HAs to EF stimulation may be involved in wound healing and neural regeneration, which could be utilized as a novel treatment strategy in brain injury.
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Affiliation(s)
- Chun Yang
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, People's Republic of China; Shanghai Institute of Head Trauma, Shanghai 200127, People's Republic of China
| | - Lei Wang
- Department of Neurosurgery, the Yuhuangding Hospital, Yantai 264000, People's Republic of China
| | - Weiji Weng
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, People's Republic of China; Department of Biochemistry and Molecular Cell Biology, Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200127, People's Republic of China
| | - Shen Wang
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, People's Republic of China; Shanghai Institute of Head Trauma, Shanghai 200127, People's Republic of China
| | - Yuxiao Ma
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, People's Republic of China; Shanghai Institute of Head Trauma, Shanghai 200127, People's Republic of China
| | - Qing Mao
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, People's Republic of China; Shanghai Institute of Head Trauma, Shanghai 200127, People's Republic of China
| | - Guoyi Gao
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, People's Republic of China
| | - Rui Chen
- Department of Plastic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, People's Republic of China.
| | - Junfeng Feng
- Department of Neurosurgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai 200127, People's Republic of China; Shanghai Institute of Head Trauma, Shanghai 200127, People's Republic of China.
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15
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Yang R, Wang H, Wen J, Ma K, Chen D, Chen Z, Huang C. Regulation of microglial process elongation, a featured characteristic of microglial plasticity. Pharmacol Res 2018; 139:286-297. [PMID: 30476531 DOI: 10.1016/j.phrs.2018.11.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 09/08/2018] [Accepted: 11/20/2018] [Indexed: 12/16/2022]
Abstract
Microglia, a type of glia within the brain characterized by a ramified morphology, are essential for removing neuronal debris and restricting the expansion of a lesion site. Upon moderate activation, they undergo a transformation in morphology inducing beneficial responses. However, upon strong stimulation, they mediate neuronal damage via production of pro-inflammatory cytokines. The inhibition of this cascade is considered an effective strategy for neuroinflammation-associated disorder therapy. During this pathological activation microglia also undergo a shortening of process length which contributes to the pathogenesis of such disorders. Thus, microglial plasticity should be considered to have two components: one is the production of inflammatory mediators, and the other is the dynamic changes in their processes. The former role has been well-documented in previous studies, while the latter one remains largely unknown. Recently, we and others have reported that the elongation of microglial process is associated with the transformation of microglia from a pro-inflammatory to an anti-inflammatory state, suggesting that the shortening of process length would make the microglia lose their ability to restrict pathological injury, while the elongation of microglial process would help attenuate neuroinflammation. Compared with the traditional anti-neuroinflammatory strategy, stimulating elongation of microglial process not only reduces the production of pro-inflammatory cytokines, but restores the ability of microglia to scan their surrounding environments, thus rendering their homeostasis regulation more effective. In this review, we provide a discussion of the factors that regulate microglial process elongation in vitro and in vivo, aiming to further drive the understanding of microglial process plasticity.
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Affiliation(s)
- Rongrong Yang
- Department of Anesthesiology, Affiliated Hospital of Nantong University, #20 Xisi Road, Nantong 226001, Jiangsu, China.
| | - Hui Wang
- Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong 226001, Jiangsu, China; Department of Neuroscience & Cell Biology, Rutgers-Robert Wood Johnson Medical School, 675 Hoes lane, Piscataway, 08854, NJ, United States
| | - Jie Wen
- Beijing Allwegene Health, B-607 Wanlin Technology Mansion, 8 Malianwa North Road, Beijing 100094, China
| | - Kai Ma
- Probiotics Australia, 24-30 Blanck Street, Ormeau, QLD, 4208, Australia
| | - Dongjian Chen
- Invasive Technology Department, Nantong First People's Hospital, The Second Affiliated Hospital of Nantong University, #6 North Road Hai'er Xiang, Nantong 226001, Jiangsu, China
| | - Zhuo Chen
- Invasive Technology Department, Nantong First People's Hospital, The Second Affiliated Hospital of Nantong University, #6 North Road Hai'er Xiang, Nantong 226001, Jiangsu, China
| | - Chao Huang
- Department of Pharmacology, School of Pharmacy, Nantong University, #19 Qixiu Road, Nantong 226001, Jiangsu, China.
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16
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Sun D, Yu Z, Fang X, Liu M, Pu Y, Shao Q, Wang D, Zhao X, Huang A, Xiang Z, Zhao C, Franklin RJ, Cao L, He C. LncRNA GAS5 inhibits microglial M2 polarization and exacerbates demyelination. EMBO Rep 2017; 18:1801-1816. [PMID: 28808113 PMCID: PMC5623836 DOI: 10.15252/embr.201643668] [Citation(s) in RCA: 169] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 07/16/2017] [Accepted: 07/20/2017] [Indexed: 12/16/2022] Open
Abstract
The regulation of inflammation is pivotal for preventing the development or reoccurrence of multiple sclerosis (MS). A biased ratio of high‐M1 versus low‐M2 polarized microglia is a major pathological feature of MS. Here, using microarray screening, we identify the long noncoding RNA (lncRNA) GAS5 as an epigenetic regulator of microglial polarization. Gain‐ and loss‐of‐function studies reveal that GAS5 suppresses microglial M2 polarization. Interference with GAS5 in transplanted microglia attenuates the progression of experimental autoimmune encephalomyelitis (EAE) and promotes remyelination in a lysolecithin‐induced demyelination model. In agreement, higher levels of GAS5 are found in amoeboid‐shaped microglia in MS patients. Further, functional studies demonstrate that GAS5 suppresses transcription of TRF4, a key factor controlling M2 macrophage polarization, by recruiting the polycomb repressive complex 2 (PRC2), thereby inhibiting M2 polarization. Thus, GAS5 may be a promising target for the treatment of demyelinating diseases.
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Affiliation(s)
- Dingya Sun
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Zhongwang Yu
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Xue Fang
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Mingdong Liu
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Yingyan Pu
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Qi Shao
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Dan Wang
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Xiaolin Zhao
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Aijun Huang
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Zhenghua Xiang
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Chao Zhao
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Robin Jm Franklin
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Li Cao
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
| | - Cheng He
- Institute of Neuroscience, Key Laboratory of Molecular Neurobiology of the Ministry of Education and the Collaborative Innovation Center for Brain Science, Second Military Medical University, Shanghai, China
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Effect of Intrastriatal 6-OHDA Lesions on Extrastriatal Brain Structures in the Mouse. Mol Neurobiol 2017; 55:4240-4252. [PMID: 28616718 DOI: 10.1007/s12035-017-0637-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 05/24/2017] [Indexed: 12/14/2022]
Abstract
Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive loss of midbrain dopaminergic neurons, resulting in motor and non-motor symptoms. The underlying pathology of non-motor symptoms is poorly understood. Discussed are pathological changes of extrastriatal brain structures. In this study, we characterized histopathological alterations of extrastriatal brain structures in the 6-hydroxydopamine (6-OHDA) PD animal model. Lesions were induced by unilateral stereotactic injections of 6-OHDA into the striatum or medial forebrain bundle of adult male mice. Loss of tyrosine hydroxylase positive (TH+) fibers as well as glia activation was quantified following stereological principles. Loss of dopaminergic innervation was further investigated by western-blotting. As expected, 6-OHDA injection into the nigrostriatal route induced retrograde degeneration of dopaminergic neurons within the substantia nigra pars compacta (SNpc), less so within the ventral tegmental area. Furthermore, we observed a region-specific drop of TH+ projection fiber density in distinct cortical regions. This pathology was most pronounced in the cingulate- and motor cortex, whereas the piriform cortex was just modestly affected. Loss of cortical TH+ fibers was not paralleled by microglia or astrocyte activation. Our results demonstrate that the loss of dopaminergic neurons within the substantia nigra pars compacta is paralleled by a cortical dopaminergic denervation in the 6-OHDA model. This model serves as a valuable tool to investigate mechanisms operant during cortical pathology in PD patients. Further studies are needed to understand why cortical dopaminergic innervation is lost in this model, and what functional consequence is associated with the observed denervation.
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18
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Matyash M, Zabiegalov O, Wendt S, Matyash V, Kettenmann H. The adenosine generating enzymes CD39/CD73 control microglial processes ramification in the mouse brain. PLoS One 2017; 12:e0175012. [PMID: 28376099 PMCID: PMC5380357 DOI: 10.1371/journal.pone.0175012] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 03/20/2017] [Indexed: 02/03/2023] Open
Abstract
Microglial cells invade the brain as amoeboid precursors and acquire a highly ramified morphology in the postnatal brain. Microglia express all essential purinergic elements such as receptors, nucleoside transporters and ecto-enzymes, including CD39 (NTPDase1) and CD73 (5'-nucleotidase), which sequentially degrade extracellular ATP to adenosine. Here, we show that constitutive deletion of CD39 and CD73 or both caused an inhibition of the microglia ramified phenotype in the brain with a reduction in the length of processes, branching frequency and number of intersections with Sholl spheres. In vitro, unlike wild-type microglia, cd39-/- and cd73-/- microglial cells were less complex and did not respond to ATP with the transformation into a more ramified phenotype. In acute brain slices, wild-type microglia retracted approximately 50% of their processes within 15 min after slicing of the brain, and this phenomenon was augmented in cd39-/- mice; moreover, the elongation of microglial processes towards the source of ATP or towards a laser lesion was observed only in wild-type but not in cd39-/- microglia. An elevation of extracellular adenosine 1) by the inhibition of adenosine transport with dipyridamole, 2) by application of exogenous adenosine or 3) by degradation of endogenous ATP/ADP with apyrase enhanced spontaneous and ATP-induced ramification of cd39-/- microglia in acute brain slices and facilitated the transformation of cd39-/- and cd73-/- microglia into a ramified process-bearing phenotype in vitro. These data indicate that under normal physiological conditions, CD39 and CD73 nucleotidases together with equilibrative nucleoside transporter 1 (ENT1) control the fate of extracellular adenosine and thereby the ramification of microglial processes.
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Affiliation(s)
- Marina Matyash
- Cellular Neurosciences, Max-Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Oleksandr Zabiegalov
- Cellular Neurosciences, Max-Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Stefan Wendt
- Cellular Neurosciences, Max-Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Vitali Matyash
- Cellular Neurosciences, Max-Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- Department of Neuropathology, Charité-Universitätsmedizin Berlin, Berlin, Germany
| | - Helmut Kettenmann
- Cellular Neurosciences, Max-Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
- * E-mail:
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Watson PMD, Kavanagh E, Allenby G, Vassey M. Bioengineered 3D Glial Cell Culture Systems and Applications for Neurodegeneration and Neuroinflammation. SLAS DISCOVERY 2017; 22:583-601. [PMID: 28346104 DOI: 10.1177/2472555217691450] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Neurodegeneration and neuroinflammation are key features in a range of chronic central nervous system (CNS) diseases such as Alzheimer's and Parkinson's disease, as well as acute conditions like stroke and traumatic brain injury, for which there remains significant unmet clinical need. It is now well recognized that current cell culture methodologies are limited in their ability to recapitulate the cellular environment that is present in vivo, and there is a growing body of evidence to show that three-dimensional (3D) culture systems represent a more physiologically accurate model than traditional two-dimensional (2D) cultures. Given the complexity of the environment from which cells originate, and their various cell-cell and cell-matrix interactions, it is important to develop models that can be controlled and reproducible for drug discovery. 3D cell models have now been developed for almost all CNS cell types, including neurons, astrocytes, microglia, and oligodendrocyte cells. This review will highlight a number of current and emerging techniques for the culture of astrocytes and microglia, glial cell types with a critical role in neurodegenerative and neuroinflammatory conditions. We describe recent advances in glial cell culture using electrospun polymers and hydrogel macromolecules, and highlight how these novel culture environments influence astrocyte and microglial phenotypes in vitro, as compared to traditional 2D systems. These models will be explored to illuminate current trends in the techniques used to create 3D environments for application in research and drug discovery focused on astrocytes and microglial cells.
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Sawano T, Tsuchihashi R, Morii E, Watanabe F, Nakane K, Inagaki S. Homology analysis detects topological changes of Iba1 localization accompanied by microglial activation. Neuroscience 2017; 346:43-51. [PMID: 28077279 DOI: 10.1016/j.neuroscience.2016.12.052] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 12/21/2016] [Accepted: 12/29/2016] [Indexed: 01/01/2023]
Abstract
The state of microglial activation provides important information about the central nervous system. However, a reliable index of microglial activation in histological samples has yet to be established. Here, we show that microglial activation induces topological changes of Iba1 localization that can be detected by analysis based on homology theory. Analysis of homology was applied to images of Iba1-stained tissue sections, and the 0-dimentional Betti number (b0: the number of solid components) and the 1-dimentional Betti number (b1: the number of windows surrounded by solid components) were obtained. We defined b1/b0 as the Homology Value (HV), and investigated its validity as an index of microglial activation using cerebral ischemia model mice. Microglial activation was accompanied by changes to Iba1 localization and morphology of microglial processes. In single microglial cells, the change of Iba1 localization increased b1. Conversely, thickening or retraction of microglial processes decreased b0. Consequently, microglial activation increased the HV. The HV of a tissue area increased with proximity to the ischemic core and showed a high degree of concordance with the number of microglia expressing activation makers. Furthermore, the HV of human metastatic brain tumor tissue also increased with proximity to the tumor. These results suggest that our index, based on homology theory, can be used to correctly evaluate microglial activation in various tissue images.
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Affiliation(s)
- Toshinori Sawano
- Group of Neurobiology, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Ryo Tsuchihashi
- Group of Neurobiology, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Eiichi Morii
- Department of Pathology, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Fumiya Watanabe
- Group of Neurobiology, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Kazuaki Nakane
- Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan.
| | - Shinobu Inagaki
- Group of Neurobiology, Division of Health Sciences, Graduate School of Medicine, Osaka University, Osaka, Japan.
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Ishihara Y, Takemoto T, Itoh K, Ishida A, Yamazaki T. Dual role of superoxide dismutase 2 induced in activated microglia: oxidative stress tolerance and convergence of inflammatory responses. J Biol Chem 2015; 290:22805-17. [PMID: 26231211 DOI: 10.1074/jbc.m115.659151] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Indexed: 12/13/2022] Open
Abstract
Microglia are activated quickly in response to external pathogens or cell debris and clear these substances via the inflammatory response. However, excessive activation of microglia can be harmful to host cells due to the increased production of reactive oxygen species and proinflammatory cytokines. Superoxide dismutase 2 (SOD2) is reportedly induced under various inflammatory conditions in the central nervous system. We herein demonstrated that activated microglia strongly express SOD2 and examined the role of SOD2, focusing on regulation of the microglial activity and the susceptibility of microglia to oxidative stress. When rat primary microglia were treated with LPS, poly(I:C), peptidoglycan, or CpG oligodeoxynucleotide, respectively, the mRNA and protein levels of SOD2 largely increased. However, an increased expression of SOD2 was not detected in the primary neurons or astrocytes, indicating that SOD2 is specifically induced in microglia under inflammatory conditions. The activated microglia showed high tolerance to oxidative stress, whereas SOD2 knockdown conferred vulnerability to oxidative stress. Interestingly, the production of proinflammatory cytokines was increased in the activated microglia treated with SOD2 siRNA compared with that observed in the control siRNA-treated cells. Pretreatment with NADPH oxidase inhibitors, diphenylene iodonium and apocynin, decreased in not only reactive oxygen species generation but also the proinflammatory cytokine expression. Notably, SOD2 knockdown largely potentiated the nuclear factor κB activity in the activated microglia. Taken together, increased SOD2 conferred tolerance to oxidative stress in the microglia and decreased proinflammatory cytokine production by attenuating the nuclear factor κB activity. Therefore, SOD2 might regulate neuroinflammation by controlling the microglial activities.
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Affiliation(s)
- Yasuhiro Ishihara
- From the Laboratory of Molecular Brain Science, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan and
| | - Takuya Takemoto
- From the Laboratory of Molecular Brain Science, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan and
| | - Kouichi Itoh
- the Laboratory for Brain Science, Kagawa School of Pharmaceutical Sciences, Tokushima Bunri University, Kagawa, 769-2193, Japan
| | - Atsuhiko Ishida
- From the Laboratory of Molecular Brain Science, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan and
| | - Takeshi Yamazaki
- From the Laboratory of Molecular Brain Science, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521, Japan and
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Noto D, Sakuma H, Takahashi K, Saika R, Saga R, Yamada M, Yamamura T, Miyake S. Development of a culture system to induce microglia-like cells from haematopoietic cells. Neuropathol Appl Neurobiol 2015; 40:697-713. [PMID: 24016036 PMCID: PMC4282385 DOI: 10.1111/nan.12086] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Accepted: 09/02/2013] [Indexed: 02/01/2023]
Abstract
Aims Microglia are the resident immune cells in the central nervous system, originating from haematopoietic-derived myeloid cells. A microglial cell is a double-edged sword, which has both pro-inflammatory and anti-inflammatory functions. Although understanding the role of microglia in pathological conditions has become increasingly important, histopathology has been the only way to investigate microglia in human diseases. Methods To enable the study of microglial cells in vitro, we here establish a culture system to induce microglia-like cells from haematopoietic cells by coculture with astrocytes. The characteristics of microglia-like cells were analysed by flow cytometry and functional assay. Results We show that triggering receptor expressing on myeloid cells-2-expressing microglia-like cells could be induced from lineage negative cells or monocytes by coculture with astrocytes. Microglia-like cells exhibited lower expression of CD45 and MHC class II than macrophages, a characteristic similar to brain microglia. When introduced into brain slice cultures, these microglia-like cells changed their morphology to a ramified shape on the first day of the culture. Moreover, we demonstrated that microglia-like cells could be induced from human monocytes by coculture with astrocytes. Finally, we showed that interleukin 34 was an important factor in the induction of microglia-like cells from haematopoietic cells in addition to cell–cell contact with astrocytes. Purified microglia-like cells were suitable for further culture and functional analyses. Conclusion Development of in vitro induction system for microglia will further promote the study of human microglial cells under pathological conditions as well as aid in the screening of drugs to target microglial cells.
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Affiliation(s)
- Daisuke Noto
- Department of Immunology, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan; Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
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23
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Kraft AD. The use of glial data in human health assessments of environmental contaminants. Toxicology 2015; 333:127-136. [PMID: 25912087 DOI: 10.1016/j.tox.2015.04.011] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 04/10/2015] [Accepted: 04/21/2015] [Indexed: 11/27/2022]
Abstract
Central nervous system (CNS) glia (i.e., astrocytes, microglia, and oligodendrocytes) are essential for maintaining neuronal homeostasis, and they orchestrate an organized cellular response to CNS injury. In addition to their beneficial roles, studies have demonstrated that disrupted glial function can have disastrous consequences on neuronal health. While effects on neuron-supportive glia are important to consider when evaluating neurotoxicity risk, interpreting glial changes is not always straightforward, particularly when attempting to discern pro-neurotoxic phenotypes from homeostatic processes or adaptive responses. To better understand how glia have been characterized and used in human health assessments of environmental contaminants (e.g., chemicals), an evaluation of all finalized assessments conducted by the U.S. Environmental Protection Agency's influential Integrated Risk Information System (IRIS) program between 1987 and 2013 was performed. Human health assessments to date have placed a clear emphasis on the neuronal cell response to potential toxicants, although more recent assessments increasingly include descriptions of glial changes. However, these descriptions are generally brief and non-specific, and they primarily consist of documenting gliosis following overt neuronal injury. As research interest in this topic continues to increase, methods for evaluating changes in glia continue to be expanded and refined, and assessors' confidence in the reliability of these data is likely to rise. Thus, glial data are anticipated to have an increasingly influential impact on the interpretation of neurotoxicity risk and underlying mechanisms. As our understanding of the complex roles these cells play grows, this knowledge is expected to support the inclusion of more extensive and specific descriptions of glial changes, including informed interpretations of the potential impact on CNS health, in future human health assessments.
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Affiliation(s)
- Andrew D Kraft
- National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., N.W., Mail Code 8623P, Washington, D.C. 20460, United States.
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Cantoni C, Bollman B, Licastro D, Xie M, Mikesell R, Schmidt R, Yuede CM, Galimberti D, Olivecrona G, Klein RS, Cross AH, Otero K, Piccio L. TREM2 regulates microglial cell activation in response to demyelination in vivo. Acta Neuropathol 2015; 129:429-47. [PMID: 25631124 DOI: 10.1007/s00401-015-1388-1] [Citation(s) in RCA: 199] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Revised: 01/10/2015] [Accepted: 01/11/2015] [Indexed: 12/17/2022]
Abstract
Microglia are phagocytic cells that survey the brain and perform neuroprotective functions in response to tissue damage, but their activating receptors are largely unknown. Triggering receptor expressed on myeloid cells 2 (TREM2) is a microglial immunoreceptor whose loss-of-function mutations in humans cause presenile dementia, while genetic variants are associated with increased risk of neurodegenerative diseases. In myeloid cells, TREM2 has been involved in the regulation of phagocytosis, cell proliferation and inflammatory responses in vitro. However, it is unknown how TREM2 contributes to microglia function in vivo. Here, we identify a critical role for TREM2 in the activation and function of microglia during cuprizone (CPZ)-induced demyelination. TREM2-deficient (TREM2(-/-)) mice had defective clearance of myelin debris and more axonal pathology, resulting in impaired clinical performances compared to wild-type (WT) mice. TREM2(-/-) microglia proliferated less in areas of demyelination and were less activated, displaying a more resting morphology and decreased expression of the activation markers MHC II and inducible nitric oxide synthase as compared to WT. Mechanistically, gene expression and ultrastructural analysis of microglia suggested a defect in myelin degradation and phagosome processing during CPZ intoxication in TREM2(-/-) microglia. These findings place TREM2 as a key regulator of microglia activation in vivo in response to tissue damage.
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Affiliation(s)
- Claudia Cantoni
- Department of Neurology, Washington University School of Medicine, 660 S. Euclid Avenue, Campus Box 8111, St Louis, MO, 63110, USA
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Habib P, Beyer C. Regulation of brain microglia by female gonadal steroids. J Steroid Biochem Mol Biol 2015; 146:3-14. [PMID: 24607811 DOI: 10.1016/j.jsbmb.2014.02.018] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 02/24/2014] [Indexed: 12/31/2022]
Abstract
Microglial cells are the primary mediators of the CNS immune defense system and crucial for shaping inflammatory responses. They represent a highly dynamic cell population which is constantly moving and surveying their environment. Acute brain damage causes a local attraction and activation of this immune cell type which involves neuron-to-glia and glia-to-glia interactions. The prevailing view attributes microglia a "negative" role such as defense and debris elimination. More topical studies also suggest a protective and "positive" regulatory function. Estrogens and progestins exert anti-inflammatory and neuroprotective effects in the CNS in acute and chronic brain diseases. Recent work revealed that microglial cells express subsets of classical and non-classical estrogen and progesterone receptors in a highly dynamic way. In this review article, we would like to stress the importance of microglia for the spreading of neural damage during hypoxia, their susceptibility to functional modulation by sex steroids, the potency of sex hormones to switch microglia from a pro-inflammatory M1 to neuroprotective M2 phenotype, and the regulation of pro- and anti-inflammatory properties including the inflammasome. We will further discuss the possibility that the neuroprotective action of sex steroids in the brain involves an early and direct modulation of local microglia cell function. This article is part of a Special Issue entitled 'Sex steroids and brain disorders'.
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Affiliation(s)
- Pardes Habib
- Institute of Neuroanatomy, RWTH Aachen University, 52074 Aachen, Germany
| | - Cordian Beyer
- Institute of Neuroanatomy, RWTH Aachen University, 52074 Aachen, Germany.
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Developmental neurotoxicity of 3,3',4,4'-tetrachloroazobenzene with thyroxine deficit: Sensitivity of glia and dentate granule neurons in the absence of behavioral changes. TOXICS 2014; 2:496-532. [PMID: 26029700 PMCID: PMC4445902 DOI: 10.3390/toxics2030496] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Thyroid hormones (TH) regulate biological processes implicated in neurodevelopmental disorders and can be altered with environmental exposures. Developmental exposure to the dioxin-like compound, 3,3',4,4'-tetrachloroazobenzene (TCAB), induced a dose response deficit in serum T4 levels with no change in 3,5,3'- triiodothyronine or thyroid stimulating hormone. Female Sprague-Dawley rats were orally gavaged (corn oil, 0.1, 1.0, or 10 mg TCAB/kg/day) two weeks prior to cohabitation until post-partum day 3 and male offspring from post-natal day (PND)4-21. At PND21, the high dose showed a deficit in body weight gain. Conventional neuropathology detected no neuronal death, myelin disruption, or gliosis. Astrocytes displayed thinner and less complex processes at 1.0 and 10 mg/kg/day. At 10 mg/kg/day, microglia showed less complex processes, unbiased stereology detected fewer hippocampal CA1 pyramidal neurons and dentate granule neurons (GC) and Golgi staining of the cerebellum showed diminished Purkinje cell dendritic arbor. At PND150, normal maturation of GC number and Purkinje cell branching area was not observed in the 1.0 mg/kg/day dose group with a diminished number and branching suggestive of effects initiated during developmental exposure. No effects were observed on post-weaning behavioral assessments in control, 0.1 and 1.0mg/kg/day dose groups. The demonstrated sensitivity of hippocampal neurons and glial cells to TCAB and T4 deficit raises support for considering additional anatomical features of brain development in future DNT evaluations.
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Testing the effects of the dye Acid violet-17 on retinal function for an intraocular application in vitreo-retinal surgery. Graefes Arch Clin Exp Ophthalmol 2014; 252:1927-37. [DOI: 10.1007/s00417-014-2761-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 07/21/2014] [Accepted: 07/24/2014] [Indexed: 10/24/2022] Open
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Affiliation(s)
- Ryo Yamasaki
- Department of Neurological Therapeutics; Neurological Institute; Graduate School of Medical Sciences; Kyushu University; Fukuoka Japan
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Schizas N, Andersson B, Hilborn J, Hailer NP. Interleukin-1 receptor antagonist promotes survival of ventral horn neurons and suppresses microglial activation in mouse spinal cord slice cultures. J Neurosci Res 2014; 92:1457-65. [PMID: 24975034 DOI: 10.1002/jnr.23429] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 04/23/2014] [Accepted: 05/09/2014] [Indexed: 02/05/2023]
Abstract
Secondary damage after spinal cord injury (SCI) induces neuronal demise through neurotoxicity and inflammation, and interleukin (IL)-1β is a key inflammatory mediator. We hypothesized that IL-1β is released in spinal cord slice cultures (SCSC) and aimed at preventing the potentially neurotoxic effects of IL-1β by using interleukin-1 receptor antagonist (IL1RA). We hypothesized that IL1RA treatment enhances neuronal survival and suppresses microglial activation. SCSC were cultured up to 8 days in vitro (DIV) in the presence of IL1RA or without, either combined with trophic support using neurotrophin (NT)-3 or not. Four groups were studied: negative control, IL1RA, NT-3, and IL1RA + NT-3. IL-1β concentrations in supernatants were measured by ELISA. SCSC were immunohistochemically stained for NeuN and α-neurofilament, and microglial cells were visualized with isolectin B4 . After 8 DIV, ventral horn neurons were significantly more numerous in the IL1RA, NT-3, and IL1RA + NT-3 groups compared with negative controls. Activated microglial cells were significantly less numerous in the IL1RA, NT-3, and IL1RA + NT-3 groups compared with negative controls. Axons expanded into the collagen matrix after treatment with IL1RA, NT-3, or IL1RA + NT-3, but not in negative controls. IL-1β release from cultures peaked after 6 hr and was lowest in the IL1RA + NT-3 group. We conclude that IL-1β is released in traumatized spinal cord tissue and that IL1RA could exert its neuroprotective actions by blocking IL-1-receptors. IL1RA thereby sustains neuronal survival irrespective of the presence of additional trophic support. Microglial activation is suppressed in the presence of IL1RA, suggesting decreased inflammatory activity. IL1RA treatment approaches may have substantial impact following SCI.
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Affiliation(s)
- N Schizas
- The SpineLab, Institute of Surgical Sciences, Department of Orthopaedics, Uppsala University, SE-751 85, Uppsala, Sweden
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Wang CJ, Chen CC, Tsay HJ, Chiang FY, Wu MF, Shiao YJ. Cudrania cochinchinensis attenuates amyloid β protein-mediated microglial activation and promotes glia-related clearance of amyloid β protein. J Biomed Sci 2013; 20:55. [PMID: 23915297 PMCID: PMC3750318 DOI: 10.1186/1423-0127-20-55] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Accepted: 07/31/2013] [Indexed: 01/21/2023] Open
Abstract
Background Microglial inflammation may significantly contribute to the pathology of Alzheimer’s disease. To examine the potential of Cudrania cochinchinensis to ameliorate amyloid β protein (Aβ)-induced microglia activation, BV-2 microglial cell line, and the ramified microglia in the primary glial mixed cultured were employed. Results Lipopolysaccharide (LPS), Interferon-γ (IFN-γ), fibrillary Aβ (fAβ), or oligomeric Aβ (oAβ) were used to activate microglia. LPS and IFN-γ, but not Aβs, activated BV-2 cells to produce nitric oxide through an increase in inducible nitric oxide synthase (iNOS) expression without significant effects on cell viability of microglia. fAβ, but not oAβ, enhanced the IFN-γ-stimulated nitric oxide production and iNOS expression. The ethanol/water extracts of Cudrania cochinchinensis (CC-EW) and the purified isolated components (i.e. CCA to CCF) effectively reduced the nitric oxide production and iNOS expression stimulated by IFN-γ combined with fAβ. On the other hand, oAβ effectively activated the ramified microglia in mixed glial culture by observing the morphological alteration of the microglia from ramified to amoeboid. CC-EW and CCB effectively prohibit the Aβ-mediated morphological change of microglia. Furthermore, CC-EW and CCB effectively decreased Aβ deposition and remained Aβ in the conditioned medium suggesting the effect of CC-EW and CCB on promoting Aβ clearance. Results are expressed as mean ± S.D. and were analyzed by ANOVA with post-hoc multiple comparisons with a Bonferroni test. Conclusions The components of Cudrania cochinchinensis including CC-EW and CCB are potential for novel therapeutic intervention for Alzheimer’s disease.
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Affiliation(s)
- Chung-Jen Wang
- Division of Geriatrics, Cheng Hsin General Hospital, Taipei, Taiwan
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Stolzing A, Sethe S, Grune T. Chronically active: activation of microglial proteolysis in ageing and neurodegeneration. Redox Rep 2013; 10:207-13. [PMID: 16259788 DOI: 10.1179/135100005x70198] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
One of the microglial cell functions is the removal of modified extracellular proteins in the brain. The connection between protein oxidation, proteolysis, and microglial activation is the topic of this review. The effect of various activation agents on microglial cells with regard to changes in substrate uptake, proteolytic capacity and degradation efficiency of different types of oxidized protein materials is reviewed. It is shown that different activation stimuli initiate substrate-specific modulation for uptake and proteolysis, influencing an array of factors including receptor expression, lysosomal pH, and proteasome subunit composition. Age-related alterations in activation and proteolytic capacity in microglial cells are also discussed. In ageing, proteolytic effectiveness is diminished, while microglial cells are chronically activated and lose the oxidative burst ability, possibly supporting a 'vicious circle' of macrophage-induced neurodegeneration.
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Affiliation(s)
- Alexandra Stolzing
- Centre for Biomaterials and Tissue Engineering, Sheffield University, UK
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Torkildsen Ø, Løken-Amsrud KI, Wergeland S, Myhr KM, Holmøy T. Fat-soluble vitamins as disease modulators in multiple sclerosis. Acta Neurol Scand 2013. [PMID: 23190287 DOI: 10.1111/ane.12045] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
BACKGROUND Fat-soluble vitamins (A, D, E and K) have properties that could be relevant as modulators of disease activity in multiple sclerosis (MS). METHODS We performed a systematic search on PubMed and Medline up to May 2012, using the search strings 'vitamin A', 'retinol', 'retinal', 'carotenoids', 'vitamin D', 'vitamin E', 'alpha-tocopherol', 'vitamin K' in conjunction with 'multiple sclerosis', 'animal model' and 'experimental autoimmune encephalitis (EAE)'. In addition, the reference lists of the publications identified were examined for further citations of relevance. RESULTS There is comprehensive evidence from epidemiological, observational, and experimental studies that vitamin D may be beneficial in MS. Results from small-scale clinical studies are inconclusive, and large-scale, adequately powered, randomized, controlled trials are still lacking. For vitamin D, Oxford Centre for Evidence-Based Medicine level 2c evidence exists for a positive therapeutic effect. Evidence from animal models indicates that all the examined fat-soluble vitamins could have potential as modulators of disease activity in MS. For vitamin A and E, level 4 and 5 evidence exists for a modulatory effect in MS; for vitamin K, too few studies have been conducted to indicate an effect in humans. CONCLUSION Vitamin D is a promising candidate as modulator of disease activity in MS, and controlled studies are currently being conducted. All the fat-soluble vitamins have, however, been demonstrated to be effective in different animal models for the disease, and vitamin A and E have biological properties that could be relevant for MS pathogenesis. Thus, vitamin A and E seem to be promising candidates for future case-control and cohort studies.
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Affiliation(s)
- Ø Torkildsen
- Department of Neurology, Norwegian Multiple Sclerosis Competence Centre, Haukeland University Hospital, Bergen, Norway
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Løken-Amsrud KI, Myhr KM, Bakke SJ, Beiske AG, Bjerve KS, Bjørnarå BT, Hovdal H, Lilleås F, Midgard R, Pedersen T, Benth JŠ, Torkildsen Ø, Wergeland S, Holmøy T. Alpha-tocopherol and MRI outcomes in multiple sclerosis--association and prediction. PLoS One 2013; 8:e54417. [PMID: 23349882 PMCID: PMC3551804 DOI: 10.1371/journal.pone.0054417] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2012] [Accepted: 12/11/2012] [Indexed: 01/18/2023] Open
Abstract
Objective Alpha-tocopherol is the main vitamin E compound in humans, and has important antioxidative and immunomodulatory properties. The aim of this study was to study alpha-tocopherol concentrations and their relationship to disease activity in Norwegian multiple sclerosis (MS) patients. Methods Prospective cohort study in 88 relapsing-remitting MS (RRMS) patients, originally included in a randomised placebo-controlled trial of omega-3 fatty acids (the OFAMS study), before and during treatment with interferon beta. The patients were followed for two years with repeated 12 magnetic resonance imaging (MRI) scans and nine serum measurements of alpha-tocopherol. Results During interferon beta (IFNB) treatment, each 10 µmol/L increase in alpha-tocopherol reduced the odds (CI 95%) for simultaneous new T2 lesions by 36.8 (0.5–59.8) %, p = 0.048, and for combined unique activity by 35.4 (1.6–57.7) %, p = 0.042, in a hierarchical regression model. These associations were not significant prior to IFNB treatment, and were not noticeably changed by gender, age, body mass index, HLA-DRB1*15, treatment group, compliance, or the concentrations of 25-hydroxyvitamin D, retinol, neutralising antibodies against IFNB, or the omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid. The corresponding odds for having new T1 gadolinium enhancing lesions two months later was reduced by 65.4 (16.5–85.7) %, p = 0.019, and for new T2 lesions by 61.0 (12.4–82.6) %, p = 0.023. Conclusion During treatment with IFNB, increasing serum concentrations of alpha-tocopherol were associated with reduced odds for simultaneous and subsequent MRI disease activity in RRMS patients.
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Hinwood M, Tynan RJ, Charnley JL, Beynon SB, Day TA, Walker FR. Chronic stress induced remodeling of the prefrontal cortex: structural re-organization of microglia and the inhibitory effect of minocycline. Cereb Cortex 2012; 23:1784-97. [PMID: 22710611 DOI: 10.1093/cercor/bhs151] [Citation(s) in RCA: 210] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Recently, it has been discovered that the working memory deficits induced by exposure to chronic stress can be prevented by treating stressed animals with minocycline, a putative inhibitor of microglial activity. One of the pressing issues that now requires clarification is exactly how exposure to chronic stress modifies microglial morphology, this being a significant issue as microglial morphology is tightly coupled with their function. To examine how chronic stress alters microglial morphology, we digitally reconstructed microglia within the rat medial prefrontal cortex. Our analysis revealed that stress increased the internal complexity of microglia, enhancing ramification (i.e. branching) without altering the overall area occupied by the cell and that this effect was more pronounced in larger cells. We subsequently determined that minocycline treatment largely abolished the pro-ramifying effects of stress. With respect to mechanisms, we could not find any evidence of increased inflammation or neurodegeneration (interleukin-1β, MHC-II, CD68, terminal deoxynucleotidyl transferase dUTP nick end labeling, and activated caspase-3). We did, however, find that chronic stress markedly increased the expression of β1-integrin (CD29), a protein previously implicated in microglial ramification. Together, these findings highlight that increased ramification of microglia may represent an important neurobiological mechanism through which microglia mediate the behavioral effects of chronic psychological stress.
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Affiliation(s)
- Madeleine Hinwood
- Laboratory of Affective Neuroscience and Neuroimmunology, School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
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Harry GJ, Kraft AD. Microglia in the developing brain: a potential target with lifetime effects. Neurotoxicology 2012; 33:191-206. [PMID: 22322212 DOI: 10.1016/j.neuro.2012.01.012] [Citation(s) in RCA: 179] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/24/2012] [Accepted: 01/25/2012] [Indexed: 12/15/2022]
Abstract
Microglia are a heterogenous group of monocyte-derived cells serving multiple roles within the brain, many of which are associated with immune and macrophage like properties. These cells are known to serve a critical role during brain injury and to maintain homeostasis; yet, their defined roles during development have yet to be elucidated. Microglial actions appear to influence events associated with neuronal proliferation and differentiation during development, as well as, contribute to processes associated with the removal of dying neurons or cellular debris and management of synaptic connections. These long-lived cells display changes during injury and with aging that are critical to the maintenance of the neuronal environment over the lifespan of the organism. These processes may be altered by changes in the colonization of the brain or by inflammatory events during development. This review addresses the role of microglia during brain development, both structurally and functionally, as well as the inherent vulnerability of the developing nervous system. A framework is presented considering microglia as a critical nervous system-specific cell that can influence multiple aspects of brain development (e.g., vascularization, synaptogenesis, and myelination) and have a long term impact on the functional vulnerability of the nervous system to a subsequent insult, whether environmental, physical, age-related, or disease-related.
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Affiliation(s)
- G Jean Harry
- National Toxicology Program Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA.
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Funk JA, Gohlke J, Kraft AD, McPherson CA, Collins JB, Harry GJ. Voluntary exercise protects hippocampal neurons from trimethyltin injury: possible role of interleukin-6 to modulate tumor necrosis factor receptor-mediated neurotoxicity. Brain Behav Immun 2011; 25:1063-77. [PMID: 21435392 PMCID: PMC3138904 DOI: 10.1016/j.bbi.2011.03.012] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 03/16/2011] [Accepted: 03/16/2011] [Indexed: 01/02/2023] Open
Abstract
In the periphery, exercise induces interleukin (IL)-6 to downregulate tumor necrosis factor (TNF), elevate interleukin-1 receptor antagonist (IL-1RA), decreasing inflammation. Exercise also offers neuroprotection and facilitates brain repair. IL-6 production in the hippocampus following exercise suggests the potential of a similar protective role as in the periphery to down-regulate TNFα and inflammation. Using a chemical-induced model of hippocampal dentate granule cell death (trimethyltin, TMT 2.4 mg/kg, ip) dependent upon TNF receptor signaling, we demonstrate neuroprotection in mice with 2 weeks access to running wheel. Exercise attenuated neuronal death and diminished elevations in TNFα, TNF receptor 1, myeloid differentiation primary response gene (MyD) 88, transforming growth factor β, chemokine (C-C motif) ligand 2 (CCL2), and CCL3. Elevated mRNA levels for IL-1α, IL-1RA, occurred with injury and protection. mRNA and protein levels of IL-6 and neuronal expression of IL-6 receptor α, were elevated with injury and protection. Microarray pathway analysis supported an up-regulation of TNFα cell death signaling pathways with TMT and inhibition by exercise. IL-6 pathway recruitment occurred in both conditions. IL-6 downstream signal events differed in the level of STAT3 activation. Exercise did not increase mRNA levels of brain derived neurotrophic factor, nerve growth factor, or glial derived neurotrophic factor. In IL-6 deficient mice, exercise did not attenuate TMT-induced tremor and a diminished level of neuroprotection was observed. These data suggest a contributory role for IL-6 induced by exercise for neuroprotection in the CNS similar to that seen in the periphery.
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Affiliation(s)
- Jason A. Funk
- Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Dept of Health and Human Services, Research Triangle Park, NC
| | - Julia Gohlke
- Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Dept of Health and Human Services, Research Triangle Park, NC,Department of Environmental Health Sciences, University of Alabama at Birmingham, Birmingham, AL
| | - Andrew D. Kraft
- Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Dept of Health and Human Services, Research Triangle Park, NC
| | - Christopher A. McPherson
- Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Dept of Health and Human Services, Research Triangle Park, NC
| | - Jennifer B. Collins
- Division of Extramural Research and Training, National Institute of Environmental Health Sciences, National Institutes of Health, Dept of Health and Human Services, Research Triangle Park, NC
| | - G. Jean Harry
- Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Dept of Health and Human Services, Research Triangle Park, NC,corresponding author: G. Jean Harry, National Institute of Environmental Health Sciences, P.O. Box 12233, MD C1-04, Research Triangle Park, NC 27709. Ph. (919) 541-0927, Fax. (919) 541-4634,
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Kipp M, Norkus A, Krauspe B, Clarner T, Berger K, van der Valk P, Amor S, Beyer C. The hippocampal fimbria of cuprizone-treated animals as a structure for studying neuroprotection in multiple sclerosis. Inflamm Res 2011; 60:723-6. [PMID: 21516513 PMCID: PMC3125513 DOI: 10.1007/s00011-011-0339-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 02/17/2011] [Accepted: 04/11/2011] [Indexed: 12/27/2022] Open
Abstract
Objective and design It has been demonstrated that changes in the normal-appearing white matter (NAWM) in multiple sclerosis precede the appearance of classical lesions. The understanding of NAWM biology in an established disease model might help to clarify why some of them progress to active demyelinating lesions. Material or subjects C57BL6 male mice (19–21 g) were used in this study. Treatment Demyelination was induced by feeding mice a diet containing 0.2% cuprizone for up to 5 weeks. Methods Routine stainings (luxol fast blue, and hematoxylin and eosin) and immunohistochemistry were performed to assess myelin status and the inflammatory infiltrate. Results We demonstrated that, in the toxic demyelination cuprizone model, the corpus callosum is severely demyelinated after a 5-week cuprizone challenge (acute demyelination) whereas the fimbria of the hippocampus appear normal in routine myelin stainings. Microgliosis but not astrogliosis is evident after acute demyelination in the fimbria. Interestingly, both regions, the fimbria and the corpus callosum, demonstrated early oligodendrocyte apoptosis as well as intense microglia accumulation and activation. However, only the corpus callosum progresses to actively demyelination lesions whereas the fimbria does not. Conclusions The applied model appears suitable for elucidating pathways which promote progression of affected tissue to an active lesion.
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Affiliation(s)
- M Kipp
- Institute of Neuroanatomy, Faculty of Medicine, RWTH Aachen University, Wendlingweg 2, 52074, Aachen, Germany.
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Kraft AD, Kaltenbach LS, Lo DC, Harry GJ. Activated microglia proliferate at neurites of mutant huntingtin-expressing neurons. Neurobiol Aging 2011; 33:621.e17-33. [PMID: 21482444 DOI: 10.1016/j.neurobiolaging.2011.02.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 02/01/2011] [Accepted: 02/16/2011] [Indexed: 01/13/2023]
Abstract
In Huntington's disease (HD), mutated huntingtin (mhtt) causes striatal neurodegeneration which is paralleled by elevated microglia cell numbers. In vitro corticostriatal slice and primary neuronal culture models, in which neuronal expression of mhtt fragments drives HD-like neurotoxicity, were employed to examine wild type microglia during both the initiation and progression of neuronal pathology. As neuronal pathology progressed, microglia initially localized in the vicinity of neurons expressing mhtt fragments increased in number, demonstrated morphological evidence of activation, and expressed the proliferation marker, Ki67. These microglia were positioned along irregular neurites, but did not localize with mhtt inclusions nor exacerbate mhtt fragment-induced neurotoxicity. Prior to neuronal pathology, microglia upregulated ionized calcium binding adaptor molecule 1 (Iba1), signaling a functional shift. With neurodegeneration, interleukin-6 and complement component 1q were increased. The results suggest a stimulatory, proliferative signal for microglia present at the onset of mhtt fragment-induced neurodegeneration. Thus, microglia effect a localized inflammatory response to neuronal mhtt expression that may serve to direct microglial removal of dysfunctional neurites or aberrant synapses, as is required for reparative actions in vivo.
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Affiliation(s)
- Andrew D Kraft
- Neurotoxicology Group, Laboratory of Toxicology and Pharmacology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA
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Dehghani F, Sayan M, Conrad A, Evers J, Ghadban C, Blaheta R, Korf HW, Hailer NP. Inhibition of microglial and astrocytic inflammatory responses by the immunosuppressant mycophenolate mofetil. Neuropathol Appl Neurobiol 2011; 36:598-611. [PMID: 20609108 DOI: 10.1111/j.1365-2990.2010.01104.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
AIMS Nucleotide depletion induced by the immunosuppressant mycophenolate mofetil (MMF) has been shown to exert neuroprotective effects. It remains unclear whether nucleotide depletion directly counteracts neuronal demise or whether it inhibits microglial or astrocytic activation, thereby resulting in indirect neuroprotection. METHODS Effects of MMF on isolated microglial cells, astrocyte/microglial cell co-cultures and isolated hippocampal neurones were analysed by immunocytochemistry, quantitative morphometry, and elisa. RESULTS We found that: (i) MMF suppressed lipopolysaccharide-induced microglial secretion of interleukin-1β, tumour necrosis factor-α and nitric oxide; (ii) MMF suppressed lipopolysaccharide-induced astrocytic production of tumour necrosis factor-α but not of nitric oxide; (iii) MMF strongly inhibited proliferation of both microglial cells and astrocytes; (iv) MMF did not protect isolated hippocampal neurones from excitotoxic injury; and (v) effects of MMF on glial cells were reversed after treatment with guanosine. CONCLUSIONS Nucleotide depletion induced by MMF inhibits microglial and astrocytic activation. Microglial and astrocytic proliferation is suppressed by MMF-induced inhibition of the salvage pathway enzyme inosine monophosphate dehydrogenase. The previously observed neuroprotection after MMF treatment seems to be indirectly mediated, making this compound an interesting immunosuppressant in the treatment of acute central nervous system lesions.
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Affiliation(s)
- F Dehghani
- Dr. Senckenbergische Anatomie, Institute of Anatomy 2, Goethe-University, Frankfurt am Main, Germany.
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Toguchi M, Gonzalez D, Furukawa S, Inagaki S. Involvement of Sema4D in the control of microglia activation. Neurochem Int 2009; 55:573-80. [PMID: 19467284 DOI: 10.1016/j.neuint.2009.05.013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2009] [Revised: 05/10/2009] [Accepted: 05/15/2009] [Indexed: 11/29/2022]
Abstract
Microglia normally exist in a resting state characterized by a ramified morphology, and are responsible for immune surveillance in the CNS. However, the resting microglia rapidly transform towards an activated phenotype in response to brain injury or immunological stimuli. In certain pathological conditions, the unregulated response or over-activation of microglia can provoke severe neuronal damage. Here, we have investigated whether Semaphorin4D (Sema4D/CD100) could function as a potential factor to control activation. Microglia were cultured, activated by bacterial endotoxin lipopolysaccharide (LPS) and then, exposed to Sema4D/CD100 or conditioned medium. We found that Sema4D/CD100 negatively controlled LPS-induced morphological activation. Moreover, intracerebral injection of LPS-induced abundant microglial activated forms in mice lacking Sema4D/CD100. Sema4D/CD100 also inhibited other relevant aspects of cell activation. Treatment with Sema4D/CD100 inhibited the production of nitrites and LPS-induced microglia migration. We also provide evidence that LPS markedly upregulated Plexin-B1 expression in microglia and Sema4D/CD100 stimulated RhoA-activation in LPS-activated microglia. Taken together, these findings suggest a novel role of Sema4D/CD100 in the regulation of microglia activation providing a valuable neuroprotective tool to the CNS.
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Bialowas-McGoey LA, Lesicka A, Whitaker-Azmitia PM. Vitamin E increases S100B-mediated microglial activation in an S100B-overexpressing mouse model of pathological aging. Glia 2009; 56:1780-90. [PMID: 18649404 DOI: 10.1002/glia.20727] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
S100B is a calcium-binding protein released by astroglial cells of the brain capable of producing numerous extracellular effects. Although the direct molecular mechanism remains unknown, these effects can be trophic including differentiation, growth, recovery, and survival of neurons when the S100B protein is mainly oxidized and neurotoxic including apoptosis and neuroinflammatory processes marked by microglial activation when in a reduced state. S100B and its receptor RAGE (receptor for advanced glycation end products) have been found to be increased in Alzheimer's disease, Down syndrome, with tissue trauma and ischemia. In the current study, we examined the binding of the S100B receptor (RAGE) on microglial cells and the developmental effects of the antioxidant vitamin E on microglial activation and the upregulation of RAGE in an S100B over-expressing mouse model of pathological aging. We report that RAGE is co-localized on activated microglial cells and vitamin E induced dramatic increases in microglial activation as well as total microglial relative optical density that was accompanied by upregulation of the RAGE receptor, particularly in the CA1 region of the hippocampus. Our findings suggest further investigation into the potential role of vitamin E in reducing the oxidation state of the S100B protein and its influence on neuroinflammatory processes marked by microglial activation in vivo.
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Tambuyzer BR, Ponsaerts P, Nouwen EJ. Microglia: gatekeepers of central nervous system immunology. J Leukoc Biol 2008; 85:352-70. [DOI: 10.1189/jlb.0608385] [Citation(s) in RCA: 238] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
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Tambuyzer BR, Lambrichts I, Lenjou M, Nouwen EJ. Effects of the pig renal epithelial cell line LLC-PK1 and its conditioned medium on the phenotype of porcine microglia in vitro. Eur J Cell Biol 2007; 86:221-32. [PMID: 17337088 DOI: 10.1016/j.ejcb.2007.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Revised: 01/11/2007] [Accepted: 01/12/2007] [Indexed: 10/23/2022] Open
Abstract
Microglia are dispersed throughout the central nervous system. Under physiological circumstances they display a 'ramified' resting phenotype. In different neuropathologies microglia reversibly transform into the activated form, an amoeboid phagocyte with a broad spectrum of immune effector functions. In this study, a coculture of porcine microglia and the pig renal epithelial cell line LLC-PK1 was used to investigate microglial cell biology. The morphology of the cocultures was elucidated as well as the functionality of the microglia cells by proliferation, superoxide and phagocytosis assays. Our results demonstrate that direct intercellular contact between the two cell types was necessary for microglia to acquire a ramified morphology. Moreover, the conditioned medium of the renal cells promoted proliferation of microglia, inhibited giant cell formation and stimulated microglia to retain their capability to generate superoxide and to perform phagocytosis. In conclusion, we have constructed a cell culture system showing differentiation of microglia in vitro and keeping them in optimal conditions.
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Affiliation(s)
- Bart R Tambuyzer
- Laboratory of Neurobiology and Neuropharmacology, Department of Biomedical Sciences, University of Antwerp (UA), Universiteitsplein 1, B-2610 Wilrijk, Belgium.
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Christensen RN, Ha BK, Sun F, Bresnahan JC, Beattie MS. Kainate induces rapid redistribution of the actin cytoskeleton in ameboid microglia. J Neurosci Res 2006; 84:170-81. [PMID: 16625662 DOI: 10.1002/jnr.20865] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Microglia are key mediators of the immune response in the central nervous system (CNS). They are closely related to macrophages and undergo dramatic morphological and functional changes after CNS trauma or excitotoxic lesions. Microglia can be directly stimulated by excitatory neurotransmitters and are known to express many neurotransmitter receptors. The role of these receptors, however, is not clear. This study describes the microglial response to the glutamate receptor agonist kainate (KA) and shows via immunochemistry that the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA)-type glutamate receptor subunit GluR1 is present on cultured microglia. In the presence of 100 microM or 1 mM KA, cultured microglia underwent dramatic morphological and cytoskeletal changes as observed by time-lapse photography and quantitative confocal analysis of phalloidin labeling. KA-stimulated microglia showed condensation of cytoplasmic actin filaments, rapid de- and repolymerization, and cytoplasmic redistribution of condensed actin bundles. Rearrangement of actin filaments-thought to be involved in locomotion and phagocytosis and to indicate an increased level of activation (for reviews see Greenberg [ 1995] Trends Cell Biol. 5:93-99; Imai and Kohsaka [ 2002] Glia 40:164-174)-was significantly increased in treated vs. control cultures. Morphological plasticity and membrane ruffling were also seen. These findings suggest direct microglial excitation via glutamate receptor pathways. Thus, neurotransmitter release after brain or spinal cord injury might directly modulate the inflammatory response.
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Stolzing A, Widmer R, Jung T, Voss P, Grune T. Tocopherol-mediated modulation of age-related changes in microglial cells: turnover of extracellular oxidized protein material. Free Radic Biol Med 2006; 40:2126-35. [PMID: 16785026 DOI: 10.1016/j.freeradbiomed.2006.02.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2005] [Revised: 02/06/2006] [Accepted: 02/13/2006] [Indexed: 10/24/2022]
Abstract
Proteins accumulate during aging and form insoluble protein aggregates. Microglia are responsible for their removal from the brain. During aging, changes within the microglia might play a crucial role in the malfunctioning of these cells. Therefore, we isolated primary microglial cells from adult rats and compared their activation status and their ability to degrade proteins to that of microglial cells isolated from newborn animals. The ability of adult microglial cells to degrade proteins is substantially decreased. However, the preincubation of microglial cells with vitamin E improves significantly the degradation of such modified proteins. The degradation of proteins from apoptotic vesicles is decreased in microglia isolated from adult rats. This might be the result of a suppression of the CD36 receptor due to vitamin E treatment. We concluded that microglial cells isolated from adult organisms have different metabolic properties and seem to be a more valuable model to study age-related diseases.
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Affiliation(s)
- Alexandra Stolzing
- Department of Engineering Materials, Centre for Biomaterials and Tissue Engineering, Sheffield University, UK
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Hailer NP, Heppner FL, Haas D, Nitsch R. Astrocytic factors deactivate antigen presenting cells that invade the central nervous system. Brain Pathol 2006; 8:459-74. [PMID: 9669697 PMCID: PMC8098609 DOI: 10.1111/j.1750-3639.1998.tb00168.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We hypothesized that CNS tissue has the potential to deactivate invading monocytes/macrophages in order to maintain the immune privilege of the brain, and furthermore, that astrocytes are the cells that initiate monocyte/macrophage deactivation. To test this hypothesis, fluorescent prelabeled rat spleen macrophages with typical amoeboid morphology were transferred into organotypic hippocampal slice cultures (OHSCs), where they gradually developed a ramified morphology similar to the appearance of resting microglial cells. This morphological transformation also occurred if macrophages or monocytes were co-cultured with mixed glial cultures or with astrocytoma cells, and ramification was accompanied by reduced expression of adhesion molecules leukocyte function antigen (LFA)-1, intercellular adhesion molecule (ICAM)-1, and major histocompatibility complex (MHC)-class-II molecules. Moreover, treatment of macrophages with astrocyte culture supernatant effectively down-regulated the LPS-induced expression of adhesion- and MHC-class-II-molecules. Astrocyte supernatant-induced inhibition of adhesion and MHC-class-II-molecule expression was mimicked by transforming growth factor (TGF)-beta1, furthermore, this inhibitory effect was diminished by simultaneous treatment with neutralizing anti-TGF-beta-antibodies. In conclusion, our results suggest that astrocyte-derived, soluble factors that are present in the CNS microenvironment deactivate invading macrophages, thus contributing to the maintenance of CNS immune-privilege following impairment of blood-brain-barrier (BBB) integrity.
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Affiliation(s)
- N P Hailer
- University Hospital for Orthopedic Surgery Friedrichsheim, Frankfurt am Main, Federal Republic of Germany.
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Flanary BE, Streit WJ. Alpha-tocopherol (vitamin E) induces rapid, nonsustained proliferation in cultured rat microglia. Glia 2006; 53:669-74. [PMID: 16419088 DOI: 10.1002/glia.20313] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Microglial cells undergo cell division in vitro, as well as in vivo after brain injury. Mitotic activity of microglia suggests that they have limited life spans and rely on self-renewal to replace senescent cells. In the current study we examined long-term effects of antioxidants vitamin E and alpha-lipoic acid on cultured rat microglia with respect to proliferative ability, telomere length, telomerase activity, and interleukin-1beta (IL-1beta) production. We report that vitamin E induces dramatic microglial proliferation, as measured by MTT assay and BrdU incorporation, surpassing that of the well-known microglial mitogen granulocyte macrophage-colony stimulating factor, and therefore establishing vitamin E as the most potent, known mitogen for microglia in vitro. The high rate of microglial proliferation resulted in a concomitant decrease in telomere length and telomerase activity. Production of IL-1beta was significantly decreased in vitamin E-treated microglia in vitro. Our findings provide an impetus to investigate potential benefits of vitamin E supplementation on microglial renewal capacity in vivo during aging or after brain injury.
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Affiliation(s)
- Barry E Flanary
- Department of Neuroscience, University of Florida College of Medicine and McKnight Brain Institute,Gainesville, 32610-0244, USA
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Abstract
Microglial cells are the resident immune cells of the central nervous system. These cells defend the central nervous system against invading microorganisms and clear the debris from damaged cells. Upon activation, microglial cells produce a large number of neuroactive substances that include cytokines, proteases, and prostanoids. In addition, activated microglial cells release radicals, such as superoxide and nitric oxide, that are products of the enzymes NADPH oxidase and inducible nitric oxide synthase, respectively. Microglia-derived radicals, as well as their reactive reaction products hydrogen peroxide and peroxynitrite, have the potential to harm cells and have been implicated in contributing to oxidative damage and neuronal cell death in neurological diseases. For self-protection against oxidative damage, microglial cells are equipped with efficient antioxidative defense mechanisms. These cells contain glutathione in high concentrations, substantial activities of the antioxidative enzymes superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase, as well as NADPH-regenerating enzymes. Their good antioxidative potential protects microglial cells against oxidative damage that could impair important functions of these cells in defense and repair of the brain.
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Affiliation(s)
- Ralf Dringen
- Faculty 2 (Biology/Chemistry), University of Bremen, Bremen, Germany.
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Tahir M, Foley B, Pate G, Crean P, Moore D, McCarroll N, Walsh M. Impact of vitamin E and C supplementation on serum adhesion molecules in chronic degenerative aortic stenosis: a randomized controlled trial. Am Heart J 2005; 150:302-6. [PMID: 16086935 DOI: 10.1016/j.ahj.2004.09.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Accepted: 09/14/2004] [Indexed: 11/25/2022]
Abstract
BACKGROUND An inflammatory component has been identified in degenerative aortic stenosis (AS). The combination of vitamins E and C has been shown to have anti-inflammatory properties. The aim of this study was to determine the impact of the combination of vitamins C and E or vitamin C only on serum levels of cell adhesion molecules and C-reactive protein in patients with chronic degenerative AS, with or without concomitant coronary artery disease. METHODS AND RESULTS One hundred patients with asymptomatic or mildly symptomatic moderate AS were randomized in 2:2:1 format in an open-label trial. Forty-one patients received vitamin E (400 IU) and vitamin C (1000 mg) daily, 39 patients received vitamin C (1000 mg) only, and 20 patients were followed as controls. Serum intracellular adhesion molecule (ICAM-1), E selectin, P selectin, vascular-cellular adhesion molecule (VCAM-1), C-reactive protein, and alpha-tocopherol (vitamin E) were measured by enzyme-linked immunosorbent assay at baseline and 6 months postsupplementation. Half of the patients from each of the 2 active groups were followed for further 6 months to determine any changes after cessation of therapy. In the vitamin E and C, group there was reduction in serum ICAM-1 (298 +/- 12 to 272 +/- 12 ng/mL at 6 months, P = .0015) with a return to base line 6 months after cessation of therapy. In the vitamin C only group, there was a reduction in serum P selectin (134 +/- 10 to 118 +/- 10 ng/mL at 6 months, P = .033). All the inflammatory markers were unchanged in control group over 6 months of follow-up. CONCLUSION Vitamin E and C supplementation had modest anti-inflammatory effect in chronic degenerative AS. The clinical relevance of this would require further clarification.
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Affiliation(s)
- Muhammad Tahir
- Department of Cardiology, St James's Hospital, Dublin, Ireland
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Heppner FL, Greter M, Marino D, Falsig J, Raivich G, Hövelmeyer N, Waisman A, Rülicke T, Prinz M, Priller J, Becher B, Aguzzi A. Experimental autoimmune encephalomyelitis repressed by microglial paralysis. Nat Med 2005; 11:146-52. [PMID: 15665833 DOI: 10.1038/nm1177] [Citation(s) in RCA: 567] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2004] [Accepted: 12/02/2004] [Indexed: 12/23/2022]
Abstract
Although microglial activation occurs in inflammatory, degenerative and neoplastic central nervous system (CNS) disorders, its role in pathogenesis is unclear. We studied this question by generating CD11b-HSVTK transgenic mice, which express herpes simplex thymidine kinase in macrophages and microglia. Ganciclovir treatment of organotypic brain slice cultures derived from CD11b-HSVTK mice abolished microglial release of nitrite, proinflammatory cytokines and chemokines. Systemic ganciclovir administration to CD11b-HSVTK mice elicited hematopoietic toxicity, which was prevented by transfer of wild-type bone marrow. In bone marrow chimeras, ganciclovir blocked microglial activation in the facial nucleus upon axotomy and repressed the development of experimental autoimmune encephalomyelitis. We conclude that microglial paralysis inhibits the development and maintenance of inflammatory CNS lesions. The microglial compartment thus provides a potential therapeutic target in inflammatory CNS disorders. These results validate CD11b-HSVTK mice as a tool to study the impact of microglial activation on CNS diseases in vivo.
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Affiliation(s)
- Frank L Heppner
- Institute of Neuropathology, University Hospital Zurich, CH-8091 Zurich, Switzerland
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