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Fedorenko OY, Paderina DZ, Kornetova EG, Poltavskaya EG, Pozhidaev IV, Goncharova AA, Freidin MB, Bocharova AV, Bokhan NA, Loonen AJM, Ivanova SA. Genes of the Glutamatergic System and Tardive Dyskinesia in Patients with Schizophrenia. Diagnostics (Basel) 2022; 12:diagnostics12071521. [PMID: 35885427 PMCID: PMC9322868 DOI: 10.3390/diagnostics12071521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/16/2022] [Accepted: 06/20/2022] [Indexed: 11/17/2022] Open
Abstract
Background: Tardive dyskinesia (TD) is an extrapyramidal side effect of the long-term use of antipsychotics. In the present study, the role of glutamatergic system genes in the pathogenesis of total TD, as well as two phenotypic forms, orofacial TD and limb-truncal TD, was studied. Methods: A set of 46 SNPs of the glutamatergic system genes (GRIN2A, GRIN2B, GRIK4, GRM3, GRM7, GRM8, SLC1A2, SLC1A3, SLC17A7) was studied in a population of 704 Caucasian patients with schizophrenia. Genotyping was performed using the MassARRAY Analyzer 4 (Agena Bioscience™). Logistic regression analysis was performed to test for the association of TD with the SNPs while adjusting for confounders. Results: No statistically significant associations between the SNPs and TD were found after adjusting for multiple testing. Since three SNPs of the SLC1A2 gene demonstrated nominally significant associations, we carried out a haplotype analysis for these SNPs. This analysis identified a risk haplotype for TD comprising CAT alleles of the SLC1A2 gene SNPs rs1042113, rs10768121, and rs12361171. Nominally significant associations were identified for SLC1A3 rs2229894 and orofacial TD, as well as for GRIN2A rs7192557 and limb-truncal TD. Conclusions: Genes encoding for mGlu3, EAAT2, and EAAT1 may be involved in the development of TD in schizophrenia patients.
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Affiliation(s)
- Olga Yu. Fedorenko
- Mental Health Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, 634014 Tomsk, Russia; (O.Y.F.); (D.Z.P.); (E.G.K.); (E.G.P.); (I.V.P.); (A.A.G.); (N.A.B.); (S.A.I.)
| | - Diana Z. Paderina
- Mental Health Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, 634014 Tomsk, Russia; (O.Y.F.); (D.Z.P.); (E.G.K.); (E.G.P.); (I.V.P.); (A.A.G.); (N.A.B.); (S.A.I.)
| | - Elena G. Kornetova
- Mental Health Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, 634014 Tomsk, Russia; (O.Y.F.); (D.Z.P.); (E.G.K.); (E.G.P.); (I.V.P.); (A.A.G.); (N.A.B.); (S.A.I.)
- Department of Psychiatry, Addictology and Psychotherapy, Siberian State Medical University, 634050 Tomsk, Russia
| | - Evgeniya G. Poltavskaya
- Mental Health Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, 634014 Tomsk, Russia; (O.Y.F.); (D.Z.P.); (E.G.K.); (E.G.P.); (I.V.P.); (A.A.G.); (N.A.B.); (S.A.I.)
| | - Ivan V. Pozhidaev
- Mental Health Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, 634014 Tomsk, Russia; (O.Y.F.); (D.Z.P.); (E.G.K.); (E.G.P.); (I.V.P.); (A.A.G.); (N.A.B.); (S.A.I.)
| | - Anastasiia A. Goncharova
- Mental Health Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, 634014 Tomsk, Russia; (O.Y.F.); (D.Z.P.); (E.G.K.); (E.G.P.); (I.V.P.); (A.A.G.); (N.A.B.); (S.A.I.)
| | - Maxim B. Freidin
- Research Institute of Medical Genetics, Tomsk National Research Medical Center of the Russian Academy of Sciences, 634050 Tomsk, Russia; (M.B.F.); (A.V.B.)
- School of Biological and Behavioural Sciences, Queen Mary University of London, London E1 4NS, UK
| | - Anna V. Bocharova
- Research Institute of Medical Genetics, Tomsk National Research Medical Center of the Russian Academy of Sciences, 634050 Tomsk, Russia; (M.B.F.); (A.V.B.)
| | - Nikolay A. Bokhan
- Mental Health Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, 634014 Tomsk, Russia; (O.Y.F.); (D.Z.P.); (E.G.K.); (E.G.P.); (I.V.P.); (A.A.G.); (N.A.B.); (S.A.I.)
- Department of Psychiatry, Addictology and Psychotherapy, Siberian State Medical University, 634050 Tomsk, Russia
| | - Anton J. M. Loonen
- Unit of PharmacoTherapy, Epidemiology & Economics, Groningen Research Institute of Pharmacy, University of Groningen, 9713 AV Groningen, The Netherlands
- Correspondence:
| | - Svetlana A. Ivanova
- Mental Health Research Institute, Tomsk National Research Medical Center of the Russian Academy of Sciences, 634014 Tomsk, Russia; (O.Y.F.); (D.Z.P.); (E.G.K.); (E.G.P.); (I.V.P.); (A.A.G.); (N.A.B.); (S.A.I.)
- Department of Psychiatry, Addictology and Psychotherapy, Siberian State Medical University, 634050 Tomsk, Russia
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Wang J, Wang F, Mai D, Qu S. Molecular Mechanisms of Glutamate Toxicity in Parkinson's Disease. Front Neurosci 2020; 14:585584. [PMID: 33324150 PMCID: PMC7725716 DOI: 10.3389/fnins.2020.585584] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/28/2020] [Indexed: 01/07/2023] Open
Abstract
Parkinson’s disease (PD) is a common neurodegenerative disease, the pathological features of which include the presence of Lewy bodies and the neurodegeneration of dopaminergic neurons in the substantia nigra pars compacta. However, until recently, research on the pathogenesis and treatment of PD have progressed slowly. Glutamate and dopamine are both important central neurotransmitters in mammals. A lack of enzymatic decomposition of extracellular glutamate results in glutamate accumulating at synapses, which is mainly absorbed by excitatory amino acid transporters (EAATs). Glutamate exerts its physiological effects by binding to and activating ligand-gated ion channels [ionotropic glutamate receptors (iGluRs)] and a class of G-protein-coupled receptors [metabotropic glutamate receptors (mGluRs)]. Timely clearance of glutamate from the synaptic cleft is necessary because high levels of extracellular glutamate overactivate glutamate receptors, resulting in excitotoxic effects in the central nervous system. Additionally, increased concentrations of extracellular glutamate inhibit cystine uptake, leading to glutathione depletion and oxidative glutamate toxicity. Studies have shown that oxidative glutamate toxicity in neurons lacking functional N-methyl-D-aspartate (NMDA) receptors may represent a component of the cellular death pathway induced by excitotoxicity. The association between inflammation and excitotoxicity (i.e., immunoexcitotoxicity) has received increased attention in recent years. Glial activation induces neuroinflammation and can stimulate excessive release of glutamate, which can induce excitotoxicity and, additionally, further exacerbate neuroinflammation. Glutamate, as an important central neurotransmitter, is closely related to the occurrence and development of PD. In this review, we discuss recent progress on elucidating glutamate as a relevant neurotransmitter in PD. Additionally, we summarize the relationship and commonality among glutamate excitotoxicity, oxidative toxicity, and immunoexcitotoxicity in order to posit a holistic view and molecular mechanism of glutamate toxicity in PD.
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Affiliation(s)
- Ji Wang
- Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, China.,Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangzhou, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Fushun Wang
- Institute of Brain and Psychological Science, Sichuan Normal University, Chengdu, China.,Department of Neurosurgery, Baylor Scott & White Health, Temple, TX, United States
| | - Dongmei Mai
- Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, China.,Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangzhou, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
| | - Shaogang Qu
- Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, China.,Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangzhou, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, China
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3
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Hermes DJ, Jacobs IR, Key MC, League AF, Yadav-Samudrala BJ, Xu C, McLane VD, Nass SR, Jiang W, Meeker RB, Ignatowska-Jankowska BM, Lichtman AH, Li Z, Wu Z, Yuan H, Knapp PE, Hauser KF, Fitting S. Escalating morphine dosing in HIV-1 Tat transgenic mice with sustained Tat exposure reveals an allostatic shift in neuroinflammatory regulation accompanied by increased neuroprotective non-endocannabinoid lipid signaling molecules and amino acids. J Neuroinflammation 2020; 17:345. [PMID: 33208151 PMCID: PMC7672881 DOI: 10.1186/s12974-020-01971-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 09/29/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Human immunodeficiency virus type-1 (HIV-1) and opiates cause long-term inflammatory insult to the central nervous system (CNS) and worsen disease progression and HIV-1-related neuropathology. The combination of these proinflammatory factors reflects a devastating problem as opioids have high abuse liability and continue to be prescribed for certain patients experiencing HIV-1-related pain. METHODS Here, we examined the impact of chronic (3-month) HIV-1 transactivator of transcription (Tat) exposure to short-term (8-day), escalating morphine in HIV-1 Tat transgenic mice that express the HIV-1 Tat protein in a GFAP promoter-regulated, doxycycline (DOX)-inducible manner. In addition to assessing morphine-induced tolerance in nociceptive responses organized at spinal (i.e., tail-flick) and supraspinal (i.e., hot-plate) levels, we evaluated neuroinflammation via positron emission tomography (PET) imaging using the [18F]-PBR111 ligand, immunohistochemistry, and cytokine analyses. Further, we examined endocannabinoid (eCB) levels, related non-eCB lipids, and amino acids via mass spectrometry. RESULTS: Tat-expressing [Tat(+)] transgenic mice displayed antinociceptive tolerance in the tail withdrawal and hot-plate assays compared to control mice lacking Tat [Tat(-)]. This tolerance was accompanied by morphine-dependent increases in Iba-1 ± 3-nitrotryosine immunoreactive microglia, and alterations in pro- and anti-inflammatory cytokines, and chemokines in the spinal cord and striatum, while increases in neuroinflammation were absent by PET imaging of [18F]-PBR111 uptake. Tat and morphine exposure differentially affected eCB levels, non-eCB lipids, and specific amino acids in a region-dependent manner. In the striatum, non-eCB lipids were significantly increased by short-term, escalating morphine exposure, including peroxisome proliferator activator receptor alpha (PPAR-α) ligands N-oleoyl ethanolamide (OEA) and N-palmitoyl ethanolamide (PEA), as well as the amino acids phenylalanine and proline. In the spinal cord, Tat exposure increased amino acids leucine and valine, while morphine decreased levels of tyrosine and valine but did not affect eCBs or non-eCB lipids. CONCLUSION Overall results demonstrate that 3 months of Tat exposure increased morphine tolerance and potentially innate immune tolerance evidenced by reductions in specific cytokines (e.g., IL-1α, IL-12p40) and microglial reactivity. In contrast, short-term, escalating morphine exposure acted as a secondary stressor revealing an allostatic shift in CNS baseline inflammatory responsiveness from sustained Tat exposure.
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Affiliation(s)
- Douglas J Hermes
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | - Ian R Jacobs
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | - Megan C Key
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | - Alexis F League
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | | | - Changqing Xu
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA
| | - Virginia D McLane
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Sara R Nass
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Wei Jiang
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC, USA
- Division of Infectious Diseases, Department of Medicine, Medical University of South Carolina, Charleston, SC, USA
| | - Rick B Meeker
- Department of Neurology, University of North Carolina, Chapel Hill, NC, USA
| | | | - Aron H Lichtman
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA, USA
| | - Zibo Li
- Department of Radiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Zhanhong Wu
- Department of Radiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Hong Yuan
- Department of Radiology, School of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Pamela E Knapp
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA, USA
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA, USA
| | - Kurt F Hauser
- Department of Pharmacology & Toxicology, Virginia Commonwealth University, Richmond, VA, USA
- Department of Anatomy & Neurobiology, Virginia Commonwealth University, Richmond, VA, USA
| | - Sylvia Fitting
- Department of Psychology & Neuroscience, University of North Carolina, Chapel Hill, NC, USA.
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4
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Vargas G, Medeiros Geraldo LH, Gedeão Salomão N, Viana Paes M, Regina Souza Lima F, Carvalho Alcantara Gomes F. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and glial cells: Insights and perspectives. Brain Behav Immun Health 2020; 7:100127. [PMID: 32838339 PMCID: PMC7423575 DOI: 10.1016/j.bbih.2020.100127] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/03/2020] [Accepted: 08/07/2020] [Indexed: 12/12/2022] Open
Abstract
In December 2019, a pneumonia outbreak was reported in Wuhan, Hubei province, China. Since then, the World Health Organization declared a public health emergency of international concern due to a growing number of deaths around the globe, as well as unparalleled economic and sociodemographic consequences. The disease called coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a novel form of human coronavirus. Although coronavirus infections have been associated with neurological manifestations such as febrile seizures, convulsions, change in mental status, and encephalitis, less is known about the impact of SARS-CoV-2 in the brain. Recently, emerging evidence suggests that SARS-CoV-2 is associated with neurological alterations in COVID-19 patients with severe clinical manifestations. The molecular and cellular mechanisms involved in this process, as well as the neurotropic and neuroinvasive properties of SARS-CoV-2, are still poorly understood. Glial cells, such as astrocytes and microglia, play pivotal roles in the brain response to neuroinflammatory insults and neurodegenerative diseases. Further, accumulating evidence has shown that those cells are targets of several neurotropic viruses that severely impact their function. Glial cell dysfunctions have been associated with several neuroinflammatory diseases, suggesting that SARS-CoV-2 likely has a primary effect on these cells in addition to a secondary effect from neuronal damage. Here, we provide an overview of these data and discuss the possible implications of glial cells as targets of SARS-CoV-2. Considering the roles of microglia and astrocytes in brain inflammatory responses, we shed light on glial cells as possible drivers and potential targets of therapeutic strategies against neurological manifestations in patients with COVID-19. The main goal of this review is to highlight the need to consider glial involvement in the progression of COVID-19 and potentially include astrocytes and microglia as mediators of SARS-CoV-2-induced neurological damage.
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Affiliation(s)
- Gabriele Vargas
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | | | - Natália Gedeão Salomão
- Laboratório Interdisciplinar de Pesquisas Médicas, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz/FIOCRUZ, Rio de Janeiro, Brazil
| | - Marciano Viana Paes
- Laboratório Interdisciplinar de Pesquisas Médicas, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz/FIOCRUZ, Rio de Janeiro, Brazil
| | - Flavia Regina Souza Lima
- Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Chen Z, Zhong D, Li G. The role of microglia in viral encephalitis: a review. J Neuroinflammation 2019; 16:76. [PMID: 30967139 PMCID: PMC6454758 DOI: 10.1186/s12974-019-1443-2] [Citation(s) in RCA: 102] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 02/24/2019] [Indexed: 12/16/2022] Open
Abstract
Viral encephalitis is still very prominent around the world, and traditional antiviral therapies still have shortcomings. Some patients cannot get effective relief or suffer from serious sequelae. At present, people are studying the role of the innate immune system in viral encephalitis. Microglia, as resident cells of the central nervous system (CNS), can respond quickly to various CNS injuries including trauma, ischemia, and infection and maintain the homeostasis of CNS, but this response is not always good; sometimes, it will exacerbate damage. Studies have shown that microglia also act as a double-edged sword during viral encephalitis. On the one hand, microglia can sense ATP signals through the purinergic receptor P2Y12 and are recruited around infected neurons to exert phagocytic activity. Microglia can exert a direct antiviral effect by producing type 1 interferon (IFN-1) to induce IFN-stimulated gene (ISG) expression of themselves or indirect antiviral effects by IFN-1 acting on other cells to activate corresponding signaling pathways. In addition, microglia can also exert an antiviral effect by inducing autophagy or secreting cytokines. On the other hand, microglia mediate presynaptic membrane damage in the hippocampus through complement, resulting in long-term memory impairment and cognitive dysfunction in patients with encephalitis. Microglia mediate fetal congenital malformations caused by Zika virus (ZIKV) infection. The gene expression profile of microglia in HIV encephalitis changes, and they tend to be a pro-inflammatory type. Microglia inhibited neuronal autophagy and aggravated the damage of CNS in HIV encephalitis; E3 ubiquitin ligase Pellino (pelia) expressed by microglia promotes the replication of virus in neurons. The interaction between amyloid-β peptide (Aβ) produced by neurons and activated microglia during viral infection is uncertain. Although neurons can mediate antiviral effects by activating receptor-interacting protein kinases 3 (RIPK3) in a death-independent pathway, the RIPK3 pathway of microglia is unknown. Different brain regions have different susceptibility to viruses, and the gene expression of microglia in different brain regions is specific. The relationship between the two needs to be further confirmed. How to properly regulate the function of microglia and make it exert more anti-inflammatory effects is our next research direction.
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Affiliation(s)
- Zhuangzhuang Chen
- Department of Neurology, The First Affiliated Hospital, Harbin Medical University, 23 You Zheng Street, Harbin, 150001, Heilong Jiang Province, People's Republic of China.
| | - Di Zhong
- Department of Neurology, The First Affiliated Hospital, Harbin Medical University, 23 You Zheng Street, Harbin, 150001, Heilong Jiang Province, People's Republic of China
| | - Guozhong Li
- Department of Neurology, The First Affiliated Hospital, Harbin Medical University, 23 You Zheng Street, Harbin, 150001, Heilong Jiang Province, People's Republic of China
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Glutamine Synthetase: Localization Dictates Outcome. Genes (Basel) 2018; 9:genes9020108. [PMID: 29463059 PMCID: PMC5852604 DOI: 10.3390/genes9020108] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Revised: 02/14/2018] [Accepted: 02/15/2018] [Indexed: 01/03/2023] Open
Abstract
Glutamine synthetase (GS) is the adenosine triphosphate (ATP)-dependent enzyme that catalyses the synthesis of glutamine by condensing ammonium to glutamate. In the circulatory system, glutamine carries ammonia from muscle and brain to the kidney and liver. In brain reduction of GS activity has been suggested as a mechanism mediating neurotoxicity in neurodegenerative disorders. In cancer, the delicate balance between glutamine synthesis and catabolism is a critical event. In vitro evidence, confirmed in vivo in some cases, suggests that reduced GS activity in cancer cells associates with a more invasive and aggressive phenotype. However, GS is known to be highly expressed in cells of the tumor microenvironment, such as fibroblasts, adipocytes and immune cells, and their ability to synthesize glutamine is responsible for the acquisition of protumoral phenotypes. This has opened a new window into the complex scenario of the tumor microenvironment, in which the balance of glutamine consumption versus glutamine synthesis influences cellular function. Since GS expression responds to glutamine starvation, a lower glutamine synthesizing power due to the absence of GS in cancer cells might apply a metabolic pressure on stromal cells. This event might push stroma towards a GS-high/protumoral phenotype. When referred to stromal cells, GS expression might acquire a ‘bad’ significance to the point that GS inhibition might be considered a conceivable strategy against cancer metastasis.
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Spinal intracellular metabotropic glutamate receptor 5 (mGluR5) contributes to pain and c-fos expression in a rat model of inflammatory pain. Pain 2017; 158:705-716. [PMID: 28030475 DOI: 10.1097/j.pain.0000000000000823] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Metabotropic glutamate receptor 5 (mGluR5) is an excitatory G-protein-coupled receptor (GPCR) present in the spinal cord dorsal horn (SCDH) where it has a well-established role in pain. In addition to its traditional location on the cytoplasmic membrane, recent evidence shows that these receptors are present intracellularly on the nuclear membrane in the spinal cord dorsal horn and are implicated in neuropathic pain. Nuclear mGluR5 is a functional receptor that binds glutamate entering the cell through the neuronal glutamate transporter (GT) EAAT3 and activates transcription factor c-fos, whereas plasma membrane mGluR5 is responsible for c-jun activation. Here, we extend these findings to a model of inflammatory pain using complete Freund's adjuvant (CFA) and show that nuclear mGluR5 is also upregulated in the spinal cord dorsal horn following inflammation. We also show that pretreatment with an excitatory amino acid transporter (EAAT) inhibitor attenuates pain and decreases Fos, but not Jun, expression in complete Freund's adjuvant rats. In contrast, selective glial glutamate transporter inhibitors are pronociceptive and increase spinal glutamate concentrations. Additionally, we found that permeable mGluR5 antagonists are more effective at attenuating pain and Fos expression than nonpermeable group I mGluR antagonists. Taken together, these results suggest that under inflammatory conditions, intracellular mGluR5 is actively involved in the relay of nociceptive information in the spinal cord.
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Palmieri EM, Menga A, Lebrun A, Hooper DC, Butterfield DA, Mazzone M, Castegna A. Blockade of Glutamine Synthetase Enhances Inflammatory Response in Microglial Cells. Antioxid Redox Signal 2017; 26:351-363. [PMID: 27758118 PMCID: PMC5346956 DOI: 10.1089/ars.2016.6715] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
AIMS Microglial cells are brain-resident macrophages engaged in surveillance and maintained in a constant state of relative inactivity. However, their involvement in autoimmune diseases indicates that in pathological conditions microglia gain an inflammatory phenotype. The mechanisms underlying this change in the microglial phenotype are still unclear. Since metabolism is an important modulator of immune cell function, we focused our attention on glutamine synthetase (GS), a modulator of the response to lipopolysaccharide (LPS) activation in other cell types, which is expressed by microglia. RESULTS GS inhibition enhances release of inflammatory mediators of LPS-activated microglia in vitro, leading to perturbation of the redox balance and decreased viability of cocultured neurons. GS inhibition also decreases insulin-mediated glucose uptake in microglia. In vivo, microglia-specific GS ablation enhances expression of inflammatory markers upon LPS treatment. In the spinal cords from experimental autoimmune encephalomyelitis (EAE), GS expression levels and glutamine/glutamate ratios are reduced. INNOVATION Recently, metabolism has been highlighted as mediator of immune cell function through the discovery of mechanisms that (behind these metabolic changes) modulate the inflammatory response. The present study shows for the first time a metabolic mechanism mediating microglial response to a proinflammatory stimulus, pointing to GS activity as a master modulator of immune cell function and thus unraveling a potential therapeutic target. CONCLUSIONS Our study highlights a new role of GS in modulating immune response in microglia, providing insights into the pathogenic mechanisms associated with inflammation and new strategies of therapeutic intervention. Antioxid. Redox Signal. 26, 351-363.
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Affiliation(s)
- Erika M Palmieri
- 1 Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari , Bari, Italy
| | - Alessio Menga
- 2 National Cancer Research Center, Istituto Tumori 'Giovanni Paolo II,' Bari, Italy
| | - Aurore Lebrun
- 3 Department of Cancer Biology, Thomas Jefferson University , Philadelphia, Pennsylvania.,4 Department of Neurological Surgery, Thomas Jefferson University , Philadelphia, Pennsylvania
| | - Douglas C Hooper
- 3 Department of Cancer Biology, Thomas Jefferson University , Philadelphia, Pennsylvania.,4 Department of Neurological Surgery, Thomas Jefferson University , Philadelphia, Pennsylvania
| | - D Allan Butterfield
- 5 Department of Chemistry, University of Kentucky , Lexington, Kentucky.,6 Sanders-Brown Center on Aging, University of Kentucky , Lexington, Kentucky
| | - Massimiliano Mazzone
- 7 Laboratory of Tumor Inflammation and Angiogenesis, Department of Oncology, University of Leuven , Leuven, Belgium .,8 Laboratory of Tumor Inflammation and Angiogenesis, Vesalius Research Center, VIB, Leuven, Belgium
| | - Alessandra Castegna
- 1 Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari , Bari, Italy .,2 National Cancer Research Center, Istituto Tumori 'Giovanni Paolo II,' Bari, Italy
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Kuhn DM, Angoa-Pérez M, Thomas DM. Nucleus accumbens invulnerability to methamphetamine neurotoxicity. ILAR J 2016; 52:352-65. [PMID: 23382149 DOI: 10.1093/ilar.52.3.352] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Methamphetamine (Meth) is a neurotoxic drug of abuse that damages neurons and nerve endings throughout the central nervous system. Emerging studies of human Meth addicts using both postmortem analyses of brain tissue and noninvasive imaging studies of intact brains have confirmed that Meth causes persistent structural abnormalities. Animal and human studies have also defined a number of significant functional problems and comorbid psychiatric disorders associated with long-term Meth abuse. This review summarizes the salient features of Meth-induced neurotoxicity with a focus on the dopamine (DA) neuronal system. DA nerve endings in the caudate-putamen (CPu) are damaged by Meth in a highly delimited manner. Even within the CPu, damage is remarkably heterogeneous, with ventral and lateral aspects showing the greatest deficits. The nucleus accumbens (NAc) is largely spared the damage that accompanies binge Meth intoxication, but relatively subtle changes in the disposition of DA in its nerve endings can lead to dramatic increases in Meth-induced toxicity in the CPu and overcome the normal resistance of the NAc to damage. In contrast to the CPu, where DA neuronal deficiencies are persistent, alterations in the NAc show a partial recovery. Animal models have been indispensable in studies of the causes and consequences of Meth neurotoxicity and in the development of new therapies. This research has shown that increases in cytoplasmic DA dramatically broaden the neurotoxic profile of Meth to include brain structures not normally targeted for damage. The resistance of the NAc to Meth-induced neurotoxicity and its ability to recover reveal a fundamentally different neuroplasticity by comparison to the CPu. Recruitment of the NAc as a target of Meth neurotoxicity by alterations in DA homeostasis is significant in light of the numerous important roles played by this brain structure.
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Abstract
Human immunodeficiency virus (HIV) invades the brain early during infection and generates a chronic inflammatory microenvironment that can eventually result in neurological disease, even in the absence of significant viral replication. Thus, HIV-1 infection of the brain has been characterized both as a neuroimmunological and neurodegenerative disorder. While the brain and central nervous system (CNS) have historically been regarded as immune privileged or immunologically quiescent, newer concepts of CNS immunity suggest an important if not defining role for innate immune responses generated by glial cells. Innate immunity may be the first line of defense against HIV infection of the brain and CNS, with multiple cellular elements providing responses that can be anti-viral and neuroprotective, but also potentially neurotoxic, impairing neurogenesis and promoting neuronal apoptosis. To investigate the effects of HIV exposure on neurogenesis and neuronal survival, we have studied the responses of human neuroepithelial progenitor (NEP) cells, which undergo directed differentiation into astrocytes and neurons in vitro. We identified a group of genes that were differentially expressed in NEP-derived cells during virus exposure. This included genes that are strongly related to interferon-induced responses and antigen presentation. Moreover, we observed that the host factor apolipoprotein E influences the innate immune response expressed by these cells, with a more robust response in the apolipoprotein E3/E3 genotype cultures compared to the apolipoprotein E3/E4 counterparts. Thus, neuroepithelial progenitors and their differentiated progeny recognize HIV and respond to it by mounting an innate immune response with a vigor that is influenced by the host factor apolipoprotein E.
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Uzasci L, Nath A, Cotter R. Oxidative stress and the HIV-infected brain proteome. J Neuroimmune Pharmacol 2013; 8:1167-80. [PMID: 23475542 PMCID: PMC3714334 DOI: 10.1007/s11481-013-9444-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 02/14/2013] [Indexed: 10/27/2022]
Abstract
Human immunodeficiency virus (HIV) is capable of infiltrating the brain and infecting brain cells. In the years following HIV infection, patients show signs of various levels of neurocognitive problems termed HIV-associated neurocognitive disorders (HAND). Although the introduction of highly active antiretroviral therapy (HAART) has reduced the incidence of HIV-dementia, which is the most severe form of HAND, the milder forms have become more prevalent today due to the increased life expectancy of infected individuals. Pre-HAART era markers such as HIV RNA level, CD4+ count, TNF-α, MCP-1 and M-CSF are not able to clearly distinguish mild from advanced HAND. One promising approach for new biomarker discovery is the identification and quantitation of proteins that are post-translationally modified by oxidative and nitrosative species. The occurrence of oxidative and nitrosative stress in HIV-infected brain, both through the early direct and indirect effects of viral proteins and through the later effect on mitochondrial integrity during apoptosis, is well-established. This review will focus on how the reactive species are produced in the brain after HIV infection, the specific oxidative and nitrosative species that are involved in the post-translational modification of the brain proteome, and the methods that are currently used for the detection of such modified proteins. This review also provides an overview of related research pertaining to oxidative stress-related HAND using cerebrospinal fluid and human brain tissue.
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Affiliation(s)
- Lerna Uzasci
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA,
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Hauser KF, Fitting S, Dever SM, Podhaizer EM, Knapp PE. Opiate drug use and the pathophysiology of neuroAIDS. Curr HIV Res 2012; 10:435-52. [PMID: 22591368 PMCID: PMC3431547 DOI: 10.2174/157016212802138779] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 01/12/2012] [Accepted: 01/14/2012] [Indexed: 11/22/2022]
Abstract
Opiate abuse and HIV-1 have been described as interrelated epidemics, and even in the advent of combined anti-retroviral therapy, the additional abuse of opiates appears to result in greater neurologic and cognitive deficits. The central nervous system (CNS) is particularly vulnerable to interactive opiate-HIV-1 effects, in part because of the unique responses of microglia and astroglia. Although neurons are principally responsible for behavior and cognition, HIV-1 infection and replication in the brain is largely limited to microglia, while astroglia and perhaps glial progenitors can be latently infected. Thus, neuronal dysfunction and injury result from cellular and viral toxins originating from HIV-1 infected/exposed glia. Importantly, subsets of glial cells including oligodendrocytes, as well as neurons, express µ-opioid receptors and therefore can be direct targets for heroin and morphine (the major metabolite of heroin in the CNS), which preferentially activate µ-opioid receptors. This review highlights findings that neuroAIDS is a glially driven disease, and that opiate abuse may act at multiple glial-cell types to further compromise neuron function and survival. The ongoing, reactive cross-talk between opiate drug and HIV-1 co-exposed microglia and astroglia appears to exacerbate critical proinflammatory and excitotoxic events leading to neuron dysfunction, injury, and potentially death. Opiates enhance synaptodendritic damage and a loss of synaptic connectivity, which is viewed as the substrate of cognitive deficits. We especially emphasize that opioid signaling and interactions with HIV-1 are contextual, differing among cell types, and even within subsets of the same cell type. For example, astroglia even within a single brain region are heterogeneous in their expression of µ-, δ-, and κ-opioid receptors, as well as CXCR4 and CCR5, and Toll-like receptors. Thus, defining the distinct targets engaged by opiates in each cell type, and among brain regions, is critical to an understanding of how opiate abuse exacerbates neuroAIDS.
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Affiliation(s)
- Kurt F Hauser
- Department of Pharmacology and Toxicology, 1217 East Marshall Street, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298, USA.
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In vitro beneficial activation of microglial cells by mechanically-injured astrocytes enhances the synthesis and secretion of BDNF through p38MAPK. Neurochem Int 2012; 61:175-86. [PMID: 22561407 DOI: 10.1016/j.neuint.2012.04.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 03/20/2012] [Accepted: 04/18/2012] [Indexed: 12/30/2022]
Abstract
It has long been promulgated that microglial cells serve beneficial roles in the central nervous system (CNS). The beneficial role of microglial cells is considered to be linked with microglial activation and consequent up-regulation of various trophic factors. However, what triggers microglial activation and consequent elevated level of trophic factors, especially brain-derived neurotrophic factor (BDNF), following traumatic CNS injury has become a crucial but elusive issue. Furthermore, an effort still remains in understanding of the cellular and molecular mechanisms underlying the endogenous neuroprotection of activated microglial cells. In this study, we demonstrated that mechanically-injured astrocyte conditioned medium (ACM) could provoke beneficial activation of microglial cells and thus promote the transcription, synthesis and release of BDNF in cultured microglial cells. The microglia-derived BDNF can exerted a demonstrable biological role in promoting neurite outgrowth and intimate terminal contacts of dorsal root ganglion (DRG) neurons co-cultured with microglial cells. Moreover, ACM induced remarkable p38MAPK phosphorylation in cultured microglial cells that preceded the burst of BDNF. Activating p38-MAPK by anisomycin resulted in salutary effects similar to those seen with ACM, whereas specific inhibition of the p38MAPK by SB203580 abrogated all the positive effects of ACM, including BDNF promotion and subsequent neurite outgrowth of DRG neurite outgrowth of DRG neurons and their intimate terminal contacts with microglial cells. Together, our results indicated that the neuroprotection of the microglial source is mainly caused by micro-environmental soluble molecules released from injured astrocytes, and ACM-induced BDNF production and release from microglial cells may be mediated through p38-MAPK signaling pathway. Therefore, these findings may lay a foundation to further investigations on the microglial beneficial activation role in the repair of traumatic CNS injury and neurodegenerative diseases.
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Abstract
PURPOSE OF REVIEW The present review discusses current concepts of HIV-associated neurocognitive disorders (HAND) in the era of antiretroviral therapy (ART). As the HIV epidemic enters its fourth decade (the second decade of ART), research must address evolving factors in HAND pathogenesis. These include persistent systemic and central nervous system (CNS) inflammation, aging in the HIV-infected brain, HIV subtype (clade) distribution, concomitant use of drugs of abuse, and potential neurotoxicity of ART drugs. RECENT FINDINGS Although the severest form of HAND, HIV-associated dementia (HAD), is now rare due to ART, the persistence of milder, functionally important HAND forms persist in up to half of HIV-infected individuals. HAND prevalence may be higher in areas of Africa where different HIV subtypes predominate, and ART regimens that are more effective in suppressing CNS HIV replication can improve neurological outcomes. HAND are correlated with persistent systemic and CNS inflammation, and enhanced neuronal injury due to stimulant abuse (cocaine and methamphetamine), aging, and possibly ART drugs themselves. SUMMARY Prevention and treatment of HAND requires strategies aimed at suppressing CNS HIV replication and effects of systemic and CNS inflammation in aging and substance-abusing HIV populations. Use of improved CNS-penetrating ART must be accompanied by evaluation of potential ART neurotoxicity.
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Gras G, Samah B, Hubert A, Léone C, Porcheray F, Rimaniol AC. EAAT expression by macrophages and microglia: still more questions than answers. Amino Acids 2011; 42:221-9. [PMID: 21373769 DOI: 10.1007/s00726-011-0866-6] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 02/17/2011] [Indexed: 01/07/2023]
Abstract
Glutamate is the main excitatory amino acid, but its presence in the extracellular milieu has deleterious consequences. It may induce excitotoxicity and also compete with cystine for the use of the cystine-glutamate exchanger, blocking glutathione neosynthesis and inducing an oxidative stress-induced cell death. Both mechanisms are critical in the brain where up to 20% of total body oxygen consumption occurs. In normal conditions, the astrocytes ensure that extracellular concentration of glutamate is kept in the micromolar range, thanks to their coexpression of high-affinity glutamate transporters (EAATs) and glutamine synthetase (GS). Their protective function is nevertheless sensitive to situations such as oxidative stress or inflammatory processes. On the other hand, macrophages and microglia do not express EAATs and GS in physiological conditions and are the principal effector cells of brain inflammation. Since the late 1990s, a number of studies have now shown that both microglia and macrophages display inducible EAAT and GS expression, but the precise significance of this still remains poorly understood. Brain macrophages and microglia are sister cells but yet display differences. Both are highly sensitive to their microenvironment and can perform a variety of functions that may oppose each other. However, in the very particular environment of the healthy brain, they are maintained in a repressed state. The aim of this review is to present the current state of knowledge on brain macrophages and microglial cells activation, in order to help clarify their role in the regulation of glutamate under pathological conditions as well as its outcome.
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Affiliation(s)
- Gabriel Gras
- Division of Immuno-Virology, Institute of Emerging Diseases and Innovative Therapies, UMR E1 CEA DSV/IMETI/SIV and University Paris South-Paris 11, 18, route du Panorama, 92265, Fontenay-aux Roses, France.
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Abstract
Individuals suffering from human immunodeficiency virus type 1 (HIV-1) infection suffer from a wide range of neurological deficits. The most pronounced are the motor and cognitive deficits observed in many patients in the latter stages of HIV infection. Gross postmortem inspection shows cortical atrophy and widespread
neuronal loss. One of the more debilitating of the HIV-related syndromes is AIDS-related dementia, or HAD. Complete understanding of HIV neurotoxicity has been elusive. Both direct and indirect toxic mechanisms have been implicated in the neurotoxicity of the
HIV proteins, Tat and gp120. The glutamatergic system, nitric oxide, calcium, oxidative stress, apoptosis, and microglia have all been implicated in the pathogenesis of HIV-related neuronal degeneration. The aim of this review is to summarize the most
recent work and provide an overview to the current theories of HIV-related neurotoxicity and potential avenues of therapeutic interventions to prevent the neuronal loss and motor/cognitive deficits previously described.
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Affiliation(s)
- David R. Wallace
- Department of Pharmacology and Physiology and Department of Forensic Sciences, Center for Health Sciences, Oklahoma State University, Tulsa, OK 74107-1898, USA
- *David R. Wallace:
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Helluy S, Thomas F. Parasitic manipulation and neuroinflammation: Evidence from the system Microphallus papillorobustus (Trematoda) - Gammarus (Crustacea). Parasit Vectors 2010; 3:38. [PMID: 20398322 PMCID: PMC2874546 DOI: 10.1186/1756-3305-3-38] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2010] [Accepted: 04/15/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Neuropathological consequences of neuroinflammatory processes have been implicated in a wide range of diseases affecting the central nervous system (CNS). Glial cells, the resident immune cells of the CNS, respond to tissue injury by releasing proinflammatory cytokines and free radicals such as nitric oxide. We explored the possibility that neuroimmune responses are involved in parasitic manipulation of host behavior in a trematode-crustacean association. The cerebral larva of the flatworm Microphallus papillorobustus alters responses to environmental stimuli - and thus reflex pathways - in the crustacean Gammarus insensibilis, in a way that enhances predation of the crustacean by birds, definitive hosts of the parasite. RESULTS Immunocytochemical experiments followed by confocal microscopy were performed to study the distribution of glutamine synthetase, a glial cell marker, and nitric oxide synthase in the brain of gammarids. Astrocyte-like glia and their processes were abundant at the surface of the parasites while levels of nitric oxide synthase were elevated at the host-parasite interface in the brain of gammarids harboring mature cerebral larvae and demonstrating altered behavior. CONCLUSION Taken together these results lend support to the neuroinflammation hypothesis whereby a chronic CNS specific immune response induced by the parasite plays a role in the disruption of neuromodulation, neuronal integrity, and behavior in infected hosts.
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Affiliation(s)
- Simone Helluy
- Department of Biological Sciences, Wellesley College, Wellesley, MA 02481, USA.
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Yadav A, Collman RG. CNS inflammation and macrophage/microglial biology associated with HIV-1 infection. J Neuroimmune Pharmacol 2009; 4:430-47. [PMID: 19768553 PMCID: PMC5935112 DOI: 10.1007/s11481-009-9174-2] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Accepted: 09/03/2009] [Indexed: 10/20/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1) infection of the central nervous system (CNS) can result in neurological dysfunction with devastating consequences in a significant proportion of individuals with acquired immune deficiency syndrome. HIV-1 does not infect neurons directly but induces damage indirectly through the accumulation of activated macrophage/microglia (M/M) cells, some of which are infected, that release neurotoxic mediators including both cellular activation products and viral proteins. One mechanism for the accumulation of activated M/M involves the development in infected individuals of an activated peripheral blood monocyte population that traffics through the blood-brain barrier, a process that also serves to carry virus into CNS and establish local infection. A second mechanism involves the release by infected and activated M/M in the CNS of chemotactic mediators that recruit additional monocytes from the periphery. These activated M/M, some of which are infected, release a number of cytokines and small molecule mediators as well as viral proteins that act on bystander cells and in turn activate them, thus amplifying the cascade. These viral proteins and cellular products have neurotoxic properties as well, both directly and through induction of astrocyte dysfunction, which ultimately lead to neuronal injury and death. In patients effectively treated with antiretroviral therapy, frank dementia is now uncommon and has been replaced by milder forms of neurocognitive impairment, with less frequent and more focal neuropathology. This review summarizes key findings that support the critical role and mechanisms of monocyte/macrophage activation and inflammation as a major component for HIV-1 encephalitis or HIV-1 associated dementia.
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Affiliation(s)
- Anjana Yadav
- Department of Medicine and Center for AIDS Research, University of Pennsylvania School of Medicine, 522 Johnson Pavilion, 36th & Hamilton Walk, Philadelphia, PA 19104, USA
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Sailasuta N, Shriner K, Ross B. Evidence of reduced glutamate in the frontal lobe of HIV-seropositive patients. NMR IN BIOMEDICINE 2009; 22:326-331. [PMID: 18988228 DOI: 10.1002/nbm.1329] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Neurological complications associated with the acquired immunodeficiency syndrome, in particular, HIV-associated dementia, continue to plague those infected. We report our finding that the concentration of brain Glu is reduced in the frontal white matter region in this condition. In addition, our data appear to absolve highly active retroviral therapy (HAART) from blame, as drug-naïve patients were equally affected. Our findings suggest that Glu neurotransmission is abnormal and may be a key target for early interventions to reduce the later incidence of neurocognitive impairment and dementia among HIV-seropositive patients.
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Reduced Expression of Excitatory Amino Acid Transporter 2 and Diffuse Microglial Activation in the Cerebral Cortex in AIDS Cases With or Without HIV Encephalitis. J Neuropathol Exp Neurol 2009; 68:199-209. [DOI: 10.1097/nen.0b013e31819715df] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Impaired astrocytes and diffuse activation of microglia in the cerebral cortex in simian immunodeficiency virus-infected Macaques without simian immunodeficiency virus encephalitis. J Neuropathol Exp Neurol 2008; 67:600-11. [PMID: 18520778 DOI: 10.1097/nen.0b013e3181772ce0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Various types of neuronal damage have been reported in acquired immunodeficiency syndrome (AIDS) dementia. We previously demonstrated that inflammation and cortical damage occur independently according to viral tropism in a simian immunodeficiency virus (SIV)-infected macaque model of AIDS dementia. To elucidate the pathogenesis of cortical degeneration, we examined the frontal cortex of SIV-infected macaques and found apoptosis and decreased expression of the excitatory amino acid transporter 2 in astrocytes and diffuse activation of microglia in association with limited neuronal damage. Some activated microglia also expressed excitatory amino acid transporter 2 but not proinflammatory cytokines. No inflammatory changes were seen in the cortex or the white matter, and SIV-infected cells were not detected in or around cortical lesions either by immunohistochemistry or by the polymerase chain reaction detection of SIV genomes of extracted DNA from microdissected tissue samples. These results indicate that an astrocytic abnormality and a compensatory activation of microglia might provide a protective effect against neuronal degeneration in the frontal cortex of SIV-infected macaques without SIV encephalitis.
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Färber K, Markworth S, Pannasch U, Nolte C, Prinz V, Kronenberg G, Gertz K, Endres M, Bechmann I, Enjyoji K, Robson SC, Kettenmann H. The ectonucleotidase cd39/ENTPDase1 modulates purinergic-mediated microglial migration. Glia 2008; 56:331-41. [PMID: 18098126 DOI: 10.1002/glia.20606] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Microglia is activated by brain injury. They migrate in response to ATP and although adenosine alone has no effect on wild type microglial migration, we show that inhibition of adenosine receptors impedes ATP triggered migration. CD39 is the dominant cellular ectonucleotidase that degrades nucleotides to nucleosides, including adenosine. Importantly, ATP fails to stimulate P2 receptor mediated migration in cd39(-/-) microglia. However, the effects of ATP on migration in cd39(-/-) microglia can be restored by co-stimulation with adenosine or by addition of a soluble ectonucleotidase. We also tested the impact of cd39-deletion in a model of ischemia, in an entorhinal cortex lesion and in the facial nucleus after facial nerve lesion. The accumulation of microglia at the pathological sites was markedly decreased in cd39(-/-) animals. We conclude that the co-stimulation of purinergic and adenosine receptors is a requirement for microglial migration and that the expression of cd39 controls the ATP/adenosine balance.
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Affiliation(s)
- Katrin Färber
- Cellular Neuroscience, Max-Delbrück-Center for Molecular Medicine, Berlin, Germany
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Tilleux S, Hermans E. Neuroinflammation and regulation of glial glutamate uptake in neurological disorders. J Neurosci Res 2007; 85:2059-70. [PMID: 17497670 DOI: 10.1002/jnr.21325] [Citation(s) in RCA: 279] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Oxidative stress, neuroinflammation, and excitotoxicity are frequently considered distinct but common hallmarks of several neurological disorders, including Parkinson's disease, amyotrophic lateral sclerosis, multiple sclerosis, and Alzheimer's disease. Although neuron degeneration and death are the ultimate consequences of these pathological processes, it is now widely accepted that alterations in the function of surrounding glial cells are key features in the progression of these diseases. In response to alteration in their local environment, microglia, commonly considered the resident immune cells of the nervous parenchyma, become activated and release a variety of soluble factors. Among these, proinflammatory cytokines and free radicals actively participate in the degenerative insults. In addition, excitotoxic neuronal damage resulting from excessive glutamate is frequently associated with impaired handling of extracellular glutamate by gliotic astrocytes. Although several research projects have focused on the biochemical mechanisms of the regulation of glial glutamate transporters, a relationship between activation of microglia and modulation of astrocytic glutamate uptake is now suggested. The aim of this review is to summarize and discuss the data showing an influence of inflammatory mediators and related free radicals on the expression and activity of glial glutamate transporters.
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Affiliation(s)
- Sébastien Tilleux
- Laboratoire de Pharmacologie Expérimentale, Faculté de Médecine, Université catholique de Louvain, Brussels, Belgium
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Sheldon AL, Robinson MB. The role of glutamate transporters in neurodegenerative diseases and potential opportunities for intervention. Neurochem Int 2007; 51:333-55. [PMID: 17517448 PMCID: PMC2075474 DOI: 10.1016/j.neuint.2007.03.012] [Citation(s) in RCA: 432] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 03/28/2007] [Accepted: 03/30/2007] [Indexed: 12/20/2022]
Abstract
Extracellular concentrations of the predominant excitatory neurotransmitter, glutamate, and related excitatory amino acids are maintained at relatively low levels to ensure an appropriate signal-to-noise ratio and to prevent excessive activation of glutamate receptors that can result in cell death. The latter phenomenon is known as 'excitotoxicity' and has been associated with a wide range of acute and chronic neurodegenerative disorders, as well as disorders that result in the loss of non-neural cells such as oligodendroglia in multiple sclerosis. Unfortunately clinical trials with glutamate receptor antagonists that would logically seem to prevent the effects of excessive receptor activation have been associated with untoward side effects or little clinical benefit. In the mammalian CNS, the extracellular concentrations of glutamate are controlled by two types of transporters; these include a family of Na(+)-dependent transporters and a cystine-glutamate exchange process, referred to as system X(c)(-). In this review, we will focus primarily on the Na(+)-dependent transporters. A brief introduction to glutamate as a neurotransmitter will be followed by an overview of the properties of these transporters, including a summary of the presumed physiologic mechanisms that regulate these transporters. Many studies have provided compelling evidence that impairing the function of these transporters can increase the sensitivity of tissue to deleterious effects of aberrant activation of glutamate receptors. Over the last decade, it has become clear that many neurodegenerative disorders are associated with a change in localization and/or expression of some of the subtypes of these transporters. This would suggest that therapies directed toward enhancing transporter expression might be beneficial. However, there is also evidence that glutamate transporters might increase the susceptibility of tissue to the consequences of insults that result in a collapse of the electrochemical gradients required for normal function such as stroke. In spite of the potential adverse effects of upregulation of glutamate transporters, there is recent evidence that upregulation of one of the glutamate transporters, GLT-1 (also called EAAT2), with beta-lactam antibiotics attenuates the damage observed in models of both acute and chronic neurodegenerative disorders. While it seems somewhat unlikely that antibiotics specifically target GLT-1 expression, these studies identify a potential strategy to limit excitotoxicity. If successful, this type of approach could have widespread utility given the large number of neurodegenerative diseases associated with decreases in transporter expression and excitotoxicity. However, given the massive effort directed at developing glutamate receptor agents during the 1990s and the relatively modest advances to date, one wonders if we will maintain the patience needed to carefully understand the glutamatergic system so that it will be successfully targeted in the future.
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Affiliation(s)
- Amanda L. Sheldon
- Department of Neuroscience, University of Pennsylvania, Philadelphia, PA. 19104-4318
- Departments of Pediatrics and Pharmacology, Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA. 19104-4318
| | - Michael B. Robinson
- Departments of Pediatrics and Pharmacology, Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA. 19104-4318
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Scaravilli F, Bazille C, Gray F. Neuropathologic contributions to understanding AIDS and the central nervous system. Brain Pathol 2007; 17:197-208. [PMID: 17388950 PMCID: PMC8095617 DOI: 10.1111/j.1750-3639.2007.00047.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
This historical review describes the evolution of the pathogenetic concepts associated with infection by the Human Immunodeficiency Virus (HIV), with emphasis on the pathology of the nervous system. Although the first descriptions of damage to the nervous system in the acquired immunodeficiency syndrome (AIDS) only appeared in 1982, the dramatic diffusion of the epidemic worldwide and the invariably rapidly fatal outcome of the disease, before the introduction of efficient treatment, generated from the beginning an enormous amount of research with rethinking on a number of pathogenetic concepts. Less than 25 years after the first autopsy series of AIDS patients were published and the virus responsible for AIDS was identified, satisfactory definition and classification of a number of neuropathological complications of HIV infection have been established, leading to accurate clinical radiological and biological diagnosis of the main neurological complications of the disease, which remain a major cause of disability and death in AIDS patients. Clinical and experimental studies have provided essential insight into the pathogenesis of CNS lesions and natural history of the disease. The relatively recent introduction of highly active antiretroviral therapy (HAART) in 1995-1996 has dramatically improved the course and prognosis of HIV disease. However, there remain a number of unsolved pathogenetic issues, the most puzzling of which remains the precise mechanism of neuronal damage underlying the specific HIV-related cognitive disorders (HIV dementia). In addition, although HAART has changed the course of neurological complications of HIV infection, new issues have emerged such as the lack of improvement or even paradoxical deterioration of the neurological status in treated patients. Interpretation of these latter data remains largely speculative partly because of the small number of neuropathological studies related to the beneficial consequence of this treatment.
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Affiliation(s)
| | - Céline Bazille
- Service Central d’Anatomie et de Cytologie Pathologiques, AP‐HP, Hôpital Lariboisière—Université Paris VII, France
| | - Françoise Gray
- Service Central d’Anatomie et de Cytologie Pathologiques, AP‐HP, Hôpital Lariboisière—Université Paris VII, France
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Reynolds A, Laurie C, Mosley RL, Gendelman HE. Oxidative stress and the pathogenesis of neurodegenerative disorders. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2007; 82:297-325. [PMID: 17678968 DOI: 10.1016/s0074-7742(07)82016-2] [Citation(s) in RCA: 285] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Microglia-derived inflammatory neurotoxins play a principal role in the pathogenesis of neurodegenerative disorders including Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and HIV-associated dementia; chief among these is reactive oxygen species. The detrimental effects of oxidative stress in the brain and nervous system are primarily a result of the diminished capacity of the central nervous system to prevent ongoing oxidative damage. A spectrum of environmental cues, mitochondrial dysfunction, accumulation of aberrant misfolded proteins, inflammation, and defects in protein clearance are known to evolve and form as a result of disease progression. These factors likely affect glial function serving to accelerate the tempo of disease. Understanding the relationships between disease progression, free radical formation, neuroinflammation, and neurotoxicity is critical to elucidating disease mechanisms and the development of therapeutic modalities to combat disease processes. In an era where populations continue to age, the prevalence and incidence of age-related neurodegenerative diseases are on the rise; therefore, the need for novel therapeutic strategies that attenuate neuroinflammation and protect neurons against oxidative stress is ever more immediate.
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Affiliation(s)
- Ashley Reynolds
- Department of Pharmacology and Experimental Neuroscience, Center for Neurovirology and Neurodegenerative Disorders, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA
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Leone C, Le Pavec G, Même W, Porcheray F, Samah B, Dormont D, Gras G. Characterization of human monocyte-derived microglia-like cells. Glia 2006; 54:183-92. [PMID: 16807899 DOI: 10.1002/glia.20372] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Microglial cells are central to brain immunity and intervene in many human neurological diseases. The aim of this study was to develop a convenient cellular model for human microglial cells, suitable for HIV studies. Microglia derive from the hematogenous myelomonocytic lineage, possibly as a distinct subpopulation but in any case able to invade the CNS, proliferate, and differentiate into ameboid and then ramified microglia in the adult life. We thus attempted to derive microglia-like cells from human monocytes. When cultured with astrocyte-conditioned medium (ACM), monocytes acquired a ramified morphology, typical of microglia. They overexpressed substance P and the calcium binding protein Iba-1 and dimly expressed class II MHC, three characteristics of microglial cells. Moreover, they also expressed a potassium inward rectifier current, another microglia-specific feature. These monocyte-derived microglia-like cells (MDMi) were CD4(+)/CD14(+), evocative of an activated microglia phenotype. When treated with lipopolysaccharide (LPS), MDMi lost their overexpression of substance P, which returned to untreated monocyte-derived macrophage (MDM) level. Compared with MDM, MDMi expressed higher CD4 but lower CCR5 levels; they could be infected by HIV-1(BaL), but produced less virus progeny than MDM did. This model of human microglia may be an interesting alternative to primary microglia for large scale in vitro HIV studies and may help to better understand HIV-associated microgliosis and chronic inflammation in the brain.
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Affiliation(s)
- Cathie Leone
- Laboratoire de Neuro-Immuno-Virologie, Service de Neurovirologie UMR E-01 CEA and Université Paris-Sud XI, CRSSA, IFR13 Institut Paris Sud Cytokines, Fontenay-aux Roses, France
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31
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Persson M, Sandberg M, Hansson E, Rönnbäck L. Microglial glutamate uptake is coupled to glutathione synthesis and glutamate release. Eur J Neurosci 2006; 24:1063-70. [PMID: 16925588 DOI: 10.1111/j.1460-9568.2006.04974.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The physiological function of microglial glutamate uptake has been debated as it is about 10% of that measured for astrocytes. This study addresses how glutamate, taken up from the extracellular space, is utilized by microglia. It was found that purified rat microglia incubated for 60 min with (3)H-glutamate had an increased intracellular accumulation of (3)H-glutamate after 12 h incubation with tumour necrosis factor alpha (TNF-alpha) but not after incubation with lipopolysaccharide (LPS). Furthermore, LPS- but not TNF-alpha-treated cells showed an increased efflux of (3)H-labelled compounds, presumably glutamate through the X(C) (-) system and treatment with LPS or TNF-alpha increased the microglial glutathione concentrations and led to an increased incorporation of (3)H-glutamate into glutathione. Depending on the stimuli, 3-6% of the total labelled contents were found in the form of glutathione and 25-35% in the form of glutamate. These results show that microglial glutamate uptake is directly coupled to glutathione synthesis and release of glutamate and/or glutamate metabolites. Additionally, the increased glutathione contents after LPS or TNF-alpha treatment were able to reduce microglial cell death after H(2)O(2) challenge, showing a potential (self)-protective function for microglial glutamate transporter expression and glutathione synthesis.
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Affiliation(s)
- Mikael Persson
- Institute of Neuroscience and Physiology, Department of Clinical Neuroscience and Rehabilitation, the Sahlgrenska Academy at Göteborg University, Guldhedsgatan 19, SE-41 45 Göteborg, Sweden.
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32
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Kaul M, Zheng J, Okamoto S, Gendelman HE, Lipton SA. HIV-1 infection and AIDS: consequences for the central nervous system. Cell Death Differ 2006; 12 Suppl 1:878-92. [PMID: 15832177 DOI: 10.1038/sj.cdd.4401623] [Citation(s) in RCA: 261] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Infection with the human immunodeficiency virus-1 (HIV-1) can induce severe and debilitating neurological problems that include behavioral abnormalities, motor dysfunction and frank dementia. After infiltrating peripheral immune competent cells, in particular macrophages, HIV-1 provokes a neuropathological response involving all cell types in the brain. HIV-1 also incites activation of chemokine receptors, inflammatory mediators, extracellular matrix-degrading enzymes and glutamate receptor-mediated excitotoxicity, all of which can trigger numerous downstream signaling pathways and disrupt neuronal and glial function. This review will discuss recently uncovered pathologic neuroimmune and degenerative mechanisms contributing to neuronal damage induced by HIV-1 and potential approaches for development of future therapeutic intervention.
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Affiliation(s)
- M Kaul
- Center for Neuroscience and Aging Research, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, CA 92037, USA
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33
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Sonnet C, Lafuste P, Arnold L, Brigitte M, Poron F, Authier FJ, Chrétien F, Gherardi RK, Chazaud B. Human macrophages rescue myoblasts and myotubes from apoptosis through a set of adhesion molecular systems. J Cell Sci 2006; 119:2497-507. [PMID: 16720640 DOI: 10.1242/jcs.02988] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The mechanisms underlying stromal cell supportive functions are incompletely understood but probably implicate a mixture of cytokines, matrix components and cell adhesion molecules. Skeletal muscle uses recruited macrophages to support post-injury regeneration. We and others have previously shown that macrophages secrete mitogenic factors for myogenic cells. Here, we focused on macrophage-elicited survival signals. We demonstrated that: (1) macrophage influx is temporally correlated with the disappearance of TUNEL-positive apoptotic myogenic cells during post-injury muscle regeneration in mice; (2) direct cell-cell contacts between human macrophages and myogenic cells rescue myogenic cells from apoptosis, as assessed by decreased annexin V labelling and caspase-3 activity, and by increased DIOC-6 staining, Bcl-2 expression and phosphorylation of Akt and ERK1/2 survival pathways; (3) four pro-survival cell-cell adhesion molecular systems detected by DNA macroarray are expressed by macrophages and myogenic cells in vitro and in vivo - VCAM-1-VLA-4, ICAM-1-LFA-1, PECAM-1-PECAM-1 and CX3CL1-CX3CR1; (4) macrophages deliver anti-apoptotic signals through all four adhesion systems, as assessed by functional analyses with blocking antibodies; and (5) macrophages more strongly rescue differentiated myotubes, which must achieve adhesion-induced stabilisation of their structure to survive. Macrophages could secure these cells until they establish final association with the matrix.
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Affiliation(s)
- Corinne Sonnet
- INSERM E0011 Cellular interactions in the neuromuscular system, Faculté de Médecine, Institut National de la Santé et de la Recherche Médicale; Université Paris XII, 8 rue du Général Sarrail, 94000 Créteil, France
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34
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Porcheray F, Léone C, Samah B, Rimaniol AC, Dereuddre-Bosquet N, Gras G. Glutamate metabolism in HIV-infected macrophages: implications for the CNS. Am J Physiol Cell Physiol 2006; 291:C618-26. [PMID: 16687472 DOI: 10.1152/ajpcell.00021.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Central nervous system disorders are still a common complication of human immunodeficiency virus (HIV) infection and can lead to dementia and death. They are mostly the consequences of an inflammatory macrophagic activation and relate to glutamate-mediated excitotoxicity. However, recent studies also suggest neuroprotective aspects of macrophage activation through the expression of glutamate transporters and glutamine synthetase. We thus aimed to study whether HIV infection or activation of macrophages could modulate glutamate metabolism in these cells. We assessed the effect of HIV infection on glutamate transporter expression as well as on glutamate uptake by macrophages and showed that glutamate transport was partially decreased in the course of virus replication, whereas excitatory amino acid transporter-2 (EAAT-2) gene expression was dramatically increased. The consequences of HIV infection on glutamine synthetase were also measured and for the first time we show the functional expression of this key enzyme in macrophages. This expression was repressed during virus production. We then quantified EAAT-1 and EAAT-2 gene expression as well as glutamate uptake in differentially activated macrophages and show that the effects of HIV are not directly related to pro- or anti-inflammatory mediators. Finally, this study shows that glutamate transport by macrophages is less affected than what has been described in astrocytes. Macrophages may thus play a role in neuroprotection against glutamate in the infected brain, through their expression of both EAATs and glutamine synthetase. Because glutamate metabolism by activated macrophages is sensitive to both HIV infection and inflammation, it may thus be of potential interest as a therapeutic target in HIV encephalitis.
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Affiliation(s)
- Fabrice Porcheray
- Commissariat à l'Energie Atomique, CEA, DSV/DRM/SNV, Unité Mixte de Recherche E-01 Université Paris-Sud XI, Fontenay-aux-Roses, France
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35
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O'Shea RD, Lau CL, Farso MC, Diwakarla S, Zagami CJ, Svendsen BB, Feeney SJ, Callaway JK, Jones NM, Pow DV, Danbolt NC, Jarrott B, Beart PM. Effects of lipopolysaccharide on glial phenotype and activity of glutamate transporters: Evidence for delayed up-regulation and redistribution of GLT-1. Neurochem Int 2006; 48:604-10. [PMID: 16530295 DOI: 10.1016/j.neuint.2005.12.028] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 12/12/2005] [Accepted: 12/12/2005] [Indexed: 10/24/2022]
Abstract
Excitatory amino acid transporters (EAATs) are responsible for homeostasis of extracellular L-glutamate, and the glial transporters are functionally dominant. EAAT expression or function is altered in acute and chronic neurological conditions, but little is known about the regulation of EAATs in reactive astroglia found in such neuropathologies. These studies examined the effects of the bacterial endotoxin lipopolysaccharide (LPS) on glial EAATs in vitro. The effects of LPS (1 microg/ml, 24-72 h) on EAAT activity and expression were examined in primary cultures of mouse astrocytes. [(3)H]D-aspartate uptake increased to 129% of control by 72 h treatment with LPS. Saturation analysis revealed that apparent K(m) was unchanged whilst V(max) was significantly increased to 172% of control by 72 h LPS treatment. Biotinylation and Western blotting indicated that cell-surface expression of GLT-1 was significantly elevated (146% control) by LPS treatment whereas GLAST expression was unchanged. Confocal analyses revealed that LPS treatment resulted in cytoskeletal changes and stellation of astrocytes, with rearrangement of F-actin (as shown by phalloidin labelling). Immunocytochemistry revealed clustering of GLAST, and increased expression and redistribution of GLT-1 to the cell-surface following treatment with LPS. Similar experiments were conducted in microglia, where LPS (50 ng/ml) was found to up-regulate expression of GLT-1 at 24 and 72 h in concert with cytoskeletal changes accompanying activation. These findings suggest an association of cytoskeletal changes in glia with EAAT activity, with the predominant adaptation involving up-regulation and redistribution of GLT-1.
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Affiliation(s)
- Ross D O'Shea
- Brain Injury and Repair Program, Howard Florey Institute, Vic. 3010, Australia
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36
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Schwab JM, Brechtel K, Mueller CA, Failli V, Kaps HP, Tuli SK, Schluesener HJ. Experimental strategies to promote spinal cord regeneration--an integrative perspective. Prog Neurobiol 2006; 78:91-116. [PMID: 16487649 DOI: 10.1016/j.pneurobio.2005.12.004] [Citation(s) in RCA: 171] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2005] [Revised: 12/13/2005] [Accepted: 12/13/2005] [Indexed: 11/17/2022]
Abstract
Detailed pathophysiological findings of secondary damage phenomena after spinal cord injury (SCI) as well as the identification of inhibitory and neurotrophic proteins have yielded a plethora of experimental therapeutic approaches. Main targets are (i) to minimize secondary damage progression (neuroprotection), (ii) to foster axon conduction (neurorestoration) and (iii) to supply a permissive environment to promote axonal sprouting (neuroregenerative therapies). Pre-clinical studies have raised hope in functional recovery through the antagonism of growth inhibitors, application of growth factors, cell transplantation, and vaccination strategies. To date, even though based on successful pre-clinical animal studies, results of clinical trials are characterized by dampened effects attributable to difficulties in the study design (patient heterogeneity) and species differences. A combination of complementary therapeutic strategies might be considered pre-requisite for future synergistic approaches. Here, we line out pre-clinical interventions resulting in improved functional neurological outcome after spinal cord injury and track them on their intended way to bedside.
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Affiliation(s)
- Jan M Schwab
- Institute of Brain Research, Calwer Str. 3, University of Tuebingen, Medical School, Calwerstr. 3, 72076 Tuebingen, Germany.
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37
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Knorpp T, Robinson SR, Crack PJ, Dringen R. Glutathione peroxidase-1 contributes to the protection of glutamine synthetase in astrocytes during oxidative stress. J Neural Transm (Vienna) 2006; 113:1145-55. [PMID: 16463122 DOI: 10.1007/s00702-005-0389-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2005] [Accepted: 09/12/2005] [Indexed: 10/25/2022]
Abstract
Glutamine synthetase (GS) is an astrocytic enzyme that is essential for the glutamate-glutamine cycle between neurons and astrocytes. To measure the effects of oxidative stress on the activity of GS in astrocytes, astrocyte-rich primary cultures from the brains of wild-type and glutathione peroxidase-1 deficient mice (GPx1(-/-)) were exposed to a chronic hydrogen peroxide-generating system consisting of xanthine oxidase, hypoxanthine and superoxide dismutase. The specific activity of GS was strongly diminished by chronic exposure to hydrogen peroxide in astrocytes cultured from both mouse lines. After 60 min of oxidative stress in the presence of 5 mU/mL, 10 mU/mL and 20 mU/mL of xanthine oxidase, the specific GS activity of wild-type astrocytes was reduced to 47%, 22% and 13% of the initial activity, respectively. For all activities of xanthine oxidase applied, astrocytes from GPx1(-/-) mice experienced a significantly greater rate of GS inactivation compared to their wild-type counterparts. These results confirm that GS is sensitive to inactivation by chronic peroxide stress in viable astrocytes and show that glutathione peroxidase-1 helps to protect GS from inactivation by oxidative stress.
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Affiliation(s)
- T Knorpp
- Department of Psychology, Monash University, Clayton, Victoria, Australia
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38
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Kramer-Hämmerle S, Rothenaigner I, Wolff H, Bell JE, Brack-Werner R. Cells of the central nervous system as targets and reservoirs of the human immunodeficiency virus. Virus Res 2005; 111:194-213. [PMID: 15885841 DOI: 10.1016/j.virusres.2005.04.009] [Citation(s) in RCA: 234] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The availability of highly active antiretroviral therapies (HAART) has not eliminated HIV-1 infection of the central nervous system (CNS) or the occurrence of HIV-associated neurological problems. Thus, the neurobiology of HIV-1 is still an important issue. Here, we review key features of HIV-1-cell interactions in the CNS and their contributions to persistence and pathogenicity of HIV-1 in the CNS. HIV-1 invades the brain very soon after systemic infection. Various mechanisms have been proposed for HIV-1 entry into the CNS. The most favored hypothesis is the migration of infected cells across the blood-brain barrier ("Trojan horse" hypothesis). Virus production in the CNS is not apparent before the onset of AIDS, indicating that HIV-1 replication in the CNS is successfully controlled in pre-AIDS. Brain macrophages and microglia cells are the chief producers of HIV-1 in brains of individuals with AIDS. HIV-1 enters these cells by the CD4 receptor and mainly the CCR5 coreceptor. Various in vivo and cell culture studies indicate that cells of neuroectodermal origin, particularly astrocytes, may also be infected by HIV-1. These cells restrict virus production and serve as reservoirs for HIV-1. A limited number of studies suggest restricted infection of oligodendrocytes and neurons, although infection of these cells is still controversial. Entry of HIV-1 into neuroectodermal cells is independent of the CD4 receptor, and a number of different cell-surface molecules have been implicated as alternate receptors of HIV-1. HIV-1-associated injury of the CNS is believed to be caused by numerous soluble factors released by glial cells as a consequence of HIV-1 infection. These include both viral and cellular factors. Some of these factors can directly induce neuronal injury and death by interacting with receptors on neuronal membranes (neurotoxic factors). Others can activate uninfected cells to produce inflammatory and neurotoxic factors and/or promote infiltration of monocytes and T-lymphocytes, thus amplifying the deleterious effects of HIV-1 infection. CNS responses to HIV-1 infection also include mechanisms that enhance neuronal survival and strengthen crucial neuronal support functions. Future challenges will be to develop strategies to prevent HIV-1 spread in the brain, bolster intrinsic defense mechanisms of the brain and to elucidate the impact of long-term persistence of HIV-1 on CNS functions in individuals without AIDS.
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Affiliation(s)
- Susanne Kramer-Hämmerle
- Institute of Molecular Virology, GSF-National Research Center for Environment and Health, Ingolstädter Landstrasse 1, D-85764 Neuherberg, Germany
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Röhl C, Sievers J. Microglia is activated by astrocytes in trimethyltin intoxication. Toxicol Appl Pharmacol 2005; 204:36-45. [PMID: 15781292 DOI: 10.1016/j.taap.2004.08.007] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2004] [Accepted: 08/17/2004] [Indexed: 11/18/2022]
Abstract
Microglia participates in most acute and chronic neuropathologies and its activation appears to involve interactions with neurons and other glial cells. Trimethyltin (TMT)-induced brain damage is a well-characterized model of neurodegeneration, in which microglial activation occurs before neuronal degeneration. The aim of this in vitro study was to investigate the role of astroglia in TMT-induced microgliosis by using nitric oxide (NO), inducible NO synthase (iNOS), and morphological changes as parameters for microglial activation. Our investigation discusses (a) whether microglial cells can be activated directly by TMT; (b) if astroglial cells are capable of triggering or modulating microglial activation; (c) how the morphology and survival of microglia and astrocytes are affected by TMT treatment; and (d) whether microglial-astroglial interactions depend on direct cell contact or on soluble factors. Our results show that microglia are more vulnerable to TMT than astrocytes are and cannot be activated directly by TMT with regard to the examined parameters. In bilayer coculture with viable astroglial cells, microglia produce NO in significant amounts at subcytotoxic concentrations of TMT (20 micromol/l). At these TMT concentrations, microglial cells in coculture convert into small round cells without cell processes, whereas flat, fibroblast-like astrocytes convert into thin process bearing stellate cells with a dense and compact cell body. We conclude that astrocytes trigger microglial activation after treatment with TMT, although the mechanisms of this interaction remain unknown.
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Affiliation(s)
- Claudia Röhl
- Department of Anatomy, University of Kiel, D-24098 Kiel, Germany.
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40
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Speth C, Dierich MP, Sopper S. HIV-infection of the central nervous system: the tightrope walk of innate immunity. Mol Immunol 2005; 42:213-28. [PMID: 15488609 DOI: 10.1016/j.molimm.2004.06.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Infection of the central nervous system (CNS) by HIV is a frequent and sometimes very early event in the course of HIV pathogenesis. Possible consequences are diverse symptoms of neurological dysfunction, but also the establishment of a lifelong latent viral reservoir in the brain. Whereas in the periphery innate and adaptive immunity are equal partners, the blood-brain barrier (BBB) with its restricted access of peripheral immune effectors shifts this balance in favour of the local innate immunity. Four main elements of cerebral innate immunity are discussed in the present article, including two cell types with immunological functions and two soluble immune systems: (1) the stimulation of microglial cells as the predominant brain-resident immune cell and the main local reservoir for the virus; (2) the reaction of astrocytes in response to viral infection; (3) the activation of the local complement system as important soluble immune cascade; and (4) the role of chemokines and cytokines which help to conduct and cross-link the interplay between the different immune elements. These components of the cerebral innate immunity do not act separately from each other but form a functional immunity network. A dual role of these components with both harmful and protective effects further enhances the complexity of the mutual interactions.
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Affiliation(s)
- Cornelia Speth
- Institute of Hygiene and Social Medicine, Medical University Innsbruck and Ludwig-Boltzmann-Institute for AIDS Research, Fritz-Pregl-Str. 3, A-6020 Innsbruck, Austria.
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41
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Abstract
HIV-1, like the other lentiviruses, has evolved the ability to infect nondividing cells including macrophages. HIV-1 replication in monocytes/macrophages entails peculiar features and differs in many respects from that in CD4 T lymphocytes. HIV-1 exhibits different tropism for CD4 T cells and macrophages. The virus can enter macrophages via several routes. Mitosis is not required for nuclear import of viral DNA or for its integration into the host cell genome. Specific cellular factors are required for HIV-1 transcription in macrophages. The assembly and budding of viral particles in macrophages take place in late endosomal compartments. Viral particles can use the exosome pathway to exit cells. Given their functions in host defence against pathogens and the regulation of the immune response plus their permissivity to HIV-1 infection, monocytes/macrophages exert a dual role in HIV infection. They contribute to the establishment and persistence of HIV-1 infection, and may activate surrounding T cells favouring their infection. Furthermore, monocytes/macrophages act as a Trojan horse to transmit HIV-1 to the central nervous system. They also exhibit antiviral activity and express many molecules that inhibit HIV-1 replication. Activated microglia and macrophages may also exert a neurotrophic and neuroprotective effect on infected brain regulating glutamate metabolism or by secretion of neurotrophins. This review will discuss specific aspects of viral replication in monocytes/macrophages and the role of their interactions with the cellular environment in HIV-1 infection swinging between protection and pathogenesis.
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Affiliation(s)
- Alessia Verani
- Human Virology Unit, DIBIT, San Raffaele Scientific Institute, Milan, Italy
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42
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Matute C, Domercq M, Sánchez-Gómez MV. Glutamate-mediated glial injury: Mechanisms and clinical importance. Glia 2005; 53:212-24. [PMID: 16206168 DOI: 10.1002/glia.20275] [Citation(s) in RCA: 225] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Primary and/or secondary glial cell death can cause and/or aggravate human diseases of the central nervous system (CNS). Like neurons, glial cells are vulnerable to glutamate insults. Astrocytes, microglia, and oligodendrocytes express a wide variety of glutamate receptors and transporters that mediate many of the deleterious effects of glutamate. Astrocytes are responsible for most glutamate uptake in synaptic and nonsynaptic areas and consequently, are the major regulators of glutamate homeostasis. Microglia in turn may secrete cytokines, which can impair glutamate uptake and reduce the expression of glutamate transporters. Finally, oligodendrocytes, the myelinating cells of the CNS, are very sensitive to excessive glutamate signaling, which can lead to the apoptosis or necrosis of these cells. This review aims at summarizing the mechanisms leading to glial cell death as a consequence of alterations in glutamate signaling, and their clinical relevance. A thorough understanding of these events will undoubtedly lead to better therapeutic strategies to treat CNS diseases affecting glia and in particular, those that involve damage to white matter tracts.
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Affiliation(s)
- Carlos Matute
- Departamento de Neurociencias, Universidad del País Vasco, Leioa, Vizcaya, Spain.
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43
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Chrétien F, Le Pavec G, Vallat-Decouvelaere AV, Delisle MB, Uro-Coste E, Ironside JW, Gambetti P, Parchi P, Créminon C, Dormont D, Mikol J, Gray F, Gras G. Expression of Excitatory Amino Acid Transporter-1 (EAAT-1) in Brain Macrophages and Microglia of Patients with Prion Diseases. J Neuropathol Exp Neurol 2004; 63:1058-71. [PMID: 15535133 DOI: 10.1093/jnen/63.10.1058] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The mechanisms of neuronal apoptosis in prion diseases are unclear. Experimental studies suggest that it may result from 2 associated mechanisms: glutamate-mediated excitotoxicity and oxidative stress. Recent studies showed that activated macrophages/microglia (AMM) express excitatory amino acid transporters (EAATs) in HIV infection, suggesting that they may play a neuroprotective role by clearing extra-cellular glutamate and producing anti-oxidant glutathione. In order to test this hypothesis in prion diseases, samples from cerebral cortex, striatum, thalamus, and cerebellum from 14 patients with Creutzfeldt-Jakob disease (8 sporadic, 2 familial, 2 iatrogenic, and 2 variant), and 4 with fatal familial insomnia (3 homozygous Met/Met at codon 129 of the PRNP gene, 1 heterozygous Met/Val), and 3 controls were immunostained for EAAT-1, GFAP, HLA-DR, CD68, IL-1, caspase 3, and PrP. In prion diseases, EAAT-1 immunopositivity was found in affected areas. Only AMM, interstitial, perivascular, perineuronal (sometimes around apoptotic neurons), or close to reactive astrocytes, expressed EAAT-1. Astrocyte EAAT-1 expression was scarcely detectable in controls and was not detected in prion disease cases. The proportion of AMM expressing EAAT-1 did not correlate with the severity of neuronal apoptosis, spongiosis, astrocytosis, microgliosis, or PrP deposition, but only with disease duration. Occasional EAAT-1 expressing AMM were found in patients with short survival, whereas diffuse EAAT-1 expression by AMM was observed in cases with long survival (24 to 33 months) that most often were heterozygous for Met/Val at codon 129 of the PRNP gene. Our findings suggest that AMM may develop a partial neuroprotective function in long-lasting prion diseases, although it does not seem to efficiently prevent neurological and neuropathological deterioration. Whether this neuroprotective function of microglia is the cause or the effect of longer survival needs to be clarified.
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Affiliation(s)
- Fabrice Chrétien
- INSERM EMI0011 and Département de Pathologie, Hôpital Henri Mondor, Assistance Publique-Hôpital de Paris, Créteil, France
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44
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Rock RB, Gekker G, Hu S, Sheng WS, Cheeran M, Lokensgard JR, Peterson PK. Role of microglia in central nervous system infections. Clin Microbiol Rev 2004; 17:942-64, table of contents. [PMID: 15489356 PMCID: PMC523558 DOI: 10.1128/cmr.17.4.942-964.2004] [Citation(s) in RCA: 493] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The nature of microglia fascinated many prominent researchers in the 19th and early 20th centuries, and in a classic treatise in 1932, Pio del Rio-Hortega formulated a number of concepts regarding the function of these resident macrophages of the brain parenchyma that remain relevant to this day. However, a renaissance of interest in microglia occurred toward the end of the 20th century, fueled by the recognition of their role in neuropathogenesis of infectious agents, such as human immunodeficiency virus type 1, and by what appears to be their participation in other neurodegenerative and neuroinflammatory disorders. During the same period, insights into the physiological and pathological properties of microglia were gained from in vivo and in vitro studies of neurotropic viruses, bacteria, fungi, parasites, and prions, which are reviewed in this article. New concepts that have emerged from these studies include the importance of cytokines and chemokines produced by activated microglia in neurodegenerative and neuroprotective processes and the elegant but astonishingly complex interactions between microglia, astrocytes, lymphocytes, and neurons that underlie these processes. It is proposed that an enhanced understanding of microglia will yield improved therapies of central nervous system infections, since such therapies are, by and large, sorely needed.
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Affiliation(s)
- R Bryan Rock
- Neuroimmunology Laboratory, Minneapolis Medical Research Foundation, and University of Minnesota Medical School, USA
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45
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Vallat-Decouvelaere AV, Gray F, Chrétien F, Le Pavec G, Dormont D, Gras G. Neurotoxicité et neuroprotection, les deux facettes de l’activation microgliale au cours de l’infection par le virus de l’immunodéficience humaine (VIH). Ann Pathol 2004; 24:31-44. [PMID: 15192535 DOI: 10.1016/s0242-6498(04)93895-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Microglial cells and macrophages are the only cells within the central nervous system, in which productive HIV infection has been unquestionably demonstrated. Those cells play a key role in the origin of the neuronal dysfunction underlying HIV-related cognitive disorders. The neurotoxicity of the cells is both direct, related to HIV proteins, and indirect, through the release by activated macrophages and microglial cells (AMM) of multiple neurotoxic factors. The mechanisms of neuronal damage, the final irreversible stage of which is neuronal apoptosis, are only partly understood but appear to involve oxidative stress and glutamate-receptor mediated toxicity. On the other hand, recent experimental in vitro and in vivo studies, and neuropathological studies in HIV infected patients at different stages of the disease, tend to show that AMM express excitatory amino acid transporters (EAAT) suggesting that in addition to their neurotoxic properties, they also have a neuroprotective role by clearing extra-cellular glutamate and producing antioxidant glutathione. This neuroprotective role could counteract, at least in the early stages of the disease, the neurotoxicity of AMM explaining the discrepancy between the conspicuous microglial activation at that stage and the absence of cognitive disorder, neuronal loss and neuronal apoptosis. It could also explain the regression of the cognitive disorders in some patients who received highly active antiretroviral treatment.
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Bossuet C, Vaufrey F, Condé F, Chrétien F, Pichon J, Hantraye P, Le Grand R, Dormont D, Gras G. Up-regulation of glutamate concentration in the putamen and in the prefrontal cortex of asymptomatic SIVmac251-infected macaques without major brain involvement. J Neurochem 2004; 88:928-38. [PMID: 14756814 DOI: 10.1046/j.1471-4159.2003.02237.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We quantified putamen and prefrontal cortex metabolites in macaques with simian immunodeficiency virus infection and searched for virological and histological correlates. Fourteen asymptomatic macaques infected since 8-78 months (median: 38) were compared with eight uninfected ones. Absolute concentrations of acetate, alanine, aspartate, choline, creatine, GABA, glutamate, glutamine, lactate, myo-inositol, N-acetylaspartate, taurine and valine were determined by ex vivo proton magnetic resonance spectroscopy. Glutamate concentration in the CSF was determined by HPLC. Gliosis was assessed by glial fibrillary acidic protein and CD68 immunohistochemistry. Glutamate concentration was slightly increased in the prefrontal cortex (19%, p = 0.0152, t-test) and putamen (13%, p = 0.0354, t-test) of the infected macaques, and was unaffected in the CSF. Myo-inositol concentration was increased in the prefrontal cortex only (27%, p = 0.0136). The concentrations of glutamate and myo-inositol in the prefrontal cortex were higher in the animals with marked or intense microgliosis (p = 0.0114). The other studied metabolites, including N-acetylaspartate, were not altered. Glutamate concentration may thus increase in the cerebral parenchyma in asymptomatic animals, but is not accompanied by a detectable decrease in N-acetylaspartate concentration (neuronal dysfunction). Thus, there are probably compensatory mechanisms that may limit glutamate increase and/or counterbalance its effects.
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Affiliation(s)
- Christophe Bossuet
- Service de Neurovirologie, UMR-E1 CEA, Université Paris-Sud, Centre de Recherches du Service de Santé des Armées, Ecole Pratique des Hautes Etudes, Institut Paris-Sud Cytokines, Fontenay-aux-Roses, France
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