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Moss EM, Mahdi F, Worth CJ, Paris JJ. Physiological Corticosterone Attenuates gp120-Mediated Microglial Activation and Is Associated with Reduced Anxiety-Like Behavior in gp120-Expressing Mice. Viruses 2023; 15:v15020424. [PMID: 36851638 PMCID: PMC9965171 DOI: 10.3390/v15020424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/17/2023] [Accepted: 01/29/2023] [Indexed: 02/05/2023] Open
Abstract
Despite the benefits of combinatorial antiretroviral therapies (cART), virotoxic HIV proteins are still detectable within the central nervous system. Approximately half of all cART-treated patients contend with neurological impairments. The mechanisms underlying these effects likely involve virotoxic HIV proteins, including glycoprotein 120 (gp120). Glycoprotein-120 is neurotoxic due to its capacity to activate microglia. Corticosterone has been found to attenuate neuronal death caused by gp120-induced microglial cytokine production in vitro. However, the concentration-dependent effects of corticosterone on microglial activation states and the associated behavioral outcomes are unclear. Herein, we conducted parallel in vitro and in vivo studies to assess gp120-mediated effects on microglial activation, motor function, anxiety- and depression-like behavior, and corticosterone's capacity to attenuate these effects. We found that gp120 activated microglia in vitro, and corticosterone attenuated this effect at an optimal concentration of 100 nM. Transgenic mice expressing gp120 demonstrated greater anxiety-like behavior on an elevated plus maze, and a greater duration of gp120 exposure was associated with motor deficits and anxiety-like behavior. Circulating corticosterone was lower in gp120-expressing males and diestrous females. Greater circulating corticosterone was associated with reduced anxiety-like behavior. These findings may demonstrate a capacity for glucocorticoids to attenuate gp120-mediated neuroinflammation and anxiety-like behavior.
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Affiliation(s)
- Emaya M. Moss
- Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS 38677-1848, USA
| | - Fakhri Mahdi
- Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS 38677-1848, USA
| | - Charlie J. Worth
- Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS 38677-1848, USA
| | - Jason J. Paris
- Department of BioMolecular Sciences, School of Pharmacy, University of Mississippi, University, MS 38677-1848, USA
- Research Institute of Pharmaceutical Sciences, University of Mississippi, University, MS 38677-1848, USA
- Correspondence: ; Tel.: +1-662-915-3096
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2
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Kandel SR, Luo X, He JJ. Nef inhibits HIV transcription and gene expression in astrocytes and HIV transmission from astrocytes to CD4 + T cells. J Neurovirol 2022; 28:552-565. [PMID: 36001227 DOI: 10.1007/s13365-022-01091-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/07/2022] [Accepted: 07/27/2022] [Indexed: 01/13/2023]
Abstract
HIV infects astrocytes in a restricted manner but leads to abundant expression of Nef, a major viral factor for HIV replication and disease progression. However, the roles of Nef in HIV gene expression and replication in astrocytes and viral transfer from astrocytes to CD4+ T cells remain largely unclear. In this study, we attempted to address these issues by transfecting human primary astrocytes with HIV molecular clones with intact Nef and without Nef (a nonsense Nef mutant) and comparing gene expression and replication in astrocytes and viral transfer from astrocytes to CD4+ T cells MT4. First, we found that lack of Nef expression led to increased extracellular virus production from astrocytes and intracellular viral protein and RNA expression in astrocytes. Using a HIV LTR-driven luciferase reporter gene assay, we showed that ectopic Nef expression alone inhibited the HIV LTR promoter activity in astrocytes. Consistent with the previously established function of Nef, we showed that the infectivity of HIV derived from astrocytes with Nef expression was significantly higher than that with no Nef expression. Next, we performed the co-culture assay to determine HIV transfer from astrocytes transfected to MT4. We showed that lack of Nef expression led to significant increase in HIV transfer from astrocytes to MT4 using two HIV clones. We also used Nef-null HIV complemented with Nef in trans in the co-culture assay and demonstrated that Nef expression led to significantly decreased HIV transfer from astrocytes to MT4. Taken together, these findings support a negative role of Nef in HIV replication and pathogenesis in astrocytes.
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Affiliation(s)
- Suresh R Kandel
- Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA.,Center for Cancer Cell Biology, Immunology and Infection, Rosalind Franklin University, North Chicago, IL, 60064, USA.,School of Graduate and Postdoctoral Studies, Rosalind Franklin University, 3333 Green Bay Road, North Chicago, IL, 60064, USA
| | - Xiaoyu Luo
- Gladstone Institute of Virology, University of California at San Francisco, San Francisco, CA, 94158, USA
| | - Johnny J He
- Department of Microbiology and Immunology, Chicago Medical School, Rosalind Franklin University, North Chicago, IL, 60064, USA. .,Center for Cancer Cell Biology, Immunology and Infection, Rosalind Franklin University, North Chicago, IL, 60064, USA. .,School of Graduate and Postdoctoral Studies, Rosalind Franklin University, 3333 Green Bay Road, North Chicago, IL, 60064, USA.
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3
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Siracusano G, Finardi A, Pastori C, Martinelli V, Furlan R, Lopalco L. HIV-1 Env Does Not Enable the Development of Protective Broadly Neutralizing Antibodies in an Experimental Autoimmune Encephalomyelitis Mouse Model. Front Immunol 2021; 12:771359. [PMID: 34795677 PMCID: PMC8593332 DOI: 10.3389/fimmu.2021.771359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 10/14/2021] [Indexed: 12/03/2022] Open
Abstract
Recent studies showed that immunological tolerance may restrict the development of Env-specific autoreactive broadly neutralizing antibodies. This evidence is consistent with the finding that Env immunization of a systemic lupus erythematosus (SLE) murine model produced antibodies that neutralize tier 2 HIV-1 strains. In this study, we address the possibility of eliciting neutralizing anti-Env antibodies in other autoimmune diseases such as multiple sclerosis (MS). While, as reported for SLE, we showed for the first time that a small number of HIV-1 negative, relapsing remitting MS patients exhibited antibodies with neutralizing properties, our attempts at inducing those antibodies in a EAE mouse model of MS failed. The success in eliciting Env-specific neutralizing antibodies might be related to the specific characteristics of the autoimmune disease, or it might rely in improving the vaccination design. Studies using mouse models are useful to gain insight in how HIV-specific neutralizing antibody responses are regulated in order to develop a protective HIV-1 vaccine.
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Affiliation(s)
- Gabriel Siracusano
- Immunobiology of HIV, Division of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
| | - Annamaria Finardi
- Clinical Neuroimmunology Unit, Institute of Experimental Neurology (INSpe), Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Claudia Pastori
- Immunobiology of HIV, Division of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
| | | | - Roberto Furlan
- Clinical Neuroimmunology Unit, Institute of Experimental Neurology (INSpe), Division of Neuroscience, San Raffaele Scientific Institute, Milan, Italy
| | - Lucia Lopalco
- Immunobiology of HIV, Division of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy
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4
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Nickoloff-Bybel EA, Festa L, Meucci O, Gaskill PJ. Co-receptor signaling in the pathogenesis of neuroHIV. Retrovirology 2021; 18:24. [PMID: 34429135 PMCID: PMC8385912 DOI: 10.1186/s12977-021-00569-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 08/11/2021] [Indexed: 12/13/2022] Open
Abstract
The HIV co-receptors, CCR5 and CXCR4, are necessary for HIV entry into target cells, interacting with the HIV envelope protein, gp120, to initiate several signaling cascades thought to be important to the entry process. Co-receptor signaling may also promote the development of neuroHIV by contributing to both persistent neuroinflammation and indirect neurotoxicity. But despite the critical importance of CXCR4 and CCR5 signaling to HIV pathogenesis, there is only one therapeutic (the CCR5 inhibitor Maraviroc) that targets these receptors. Moreover, our understanding of co-receptor signaling in the specific context of neuroHIV is relatively poor. Research into co-receptor signaling has largely stalled in the past decade, possibly owing to the complexity of the signaling cascades and functions mediated by these receptors. Examining the many signaling pathways triggered by co-receptor activation has been challenging due to the lack of specific molecular tools targeting many of the proteins involved in these pathways and the wide array of model systems used across these experiments. Studies examining the impact of co-receptor signaling on HIV neuropathogenesis often show activation of multiple overlapping pathways by similar stimuli, leading to contradictory data on the effects of co-receptor activation. To address this, we will broadly review HIV infection and neuropathogenesis, examine different co-receptor mediated signaling pathways and functions, then discuss the HIV mediated signaling and the differences between activation induced by HIV and cognate ligands. We will assess the specific effects of co-receptor activation on neuropathogenesis, focusing on neuroinflammation. We will also explore how the use of substances of abuse, which are highly prevalent in people living with HIV, can exacerbate the neuropathogenic effects of co-receptor signaling. Finally, we will discuss the current state of therapeutics targeting co-receptors, highlighting challenges the field has faced and areas in which research into co-receptor signaling would yield the most therapeutic benefit in the context of HIV infection. This discussion will provide a comprehensive overview of what is known and what remains to be explored in regard to co-receptor signaling and HIV infection, and will emphasize the potential value of HIV co-receptors as a target for future therapeutic development. ![]()
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Affiliation(s)
- E A Nickoloff-Bybel
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Philadelphia, PA, 19102, USA
| | - L Festa
- Department of Basic and Translational Sciences, School of Dental Medicine, University of Pennsylvania, 240 S. 40th Street, Philadelphia, PA, 19104, USA
| | - O Meucci
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Philadelphia, PA, 19102, USA.,Department of Microbiology and Immunology, Drexel University College of Medicine, Philadelphia, PA, 19102, USA
| | - P J Gaskill
- Department of Pharmacology and Physiology, Drexel University College of Medicine, 245 N. 15th Street, Philadelphia, PA, 19102, USA.
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5
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Llewellyn GN, Alvarez-Carbonell D, Chateau M, Karn J, Cannon PM. HIV-1 infection of microglial cells in a reconstituted humanized mouse model and identification of compounds that selectively reverse HIV latency. J Neurovirol 2017; 24:192-203. [PMID: 29256041 PMCID: PMC5910454 DOI: 10.1007/s13365-017-0604-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 11/03/2017] [Accepted: 11/09/2017] [Indexed: 11/24/2022]
Abstract
Most studies of HIV latency focus on the peripheral population of resting memory T cells, but the brain also contains a distinct reservoir of HIV-infected cells in microglia, perivascular macrophages, and astrocytes. Studying HIV in the brain has been challenging, since live cells are difficult to recover from autopsy samples and primate models of SIV infection utilize viruses that are more myeloid-tropic than HIV due to the expression of Vpx. Development of a realistic small animal model would greatly advance studies of this important reservoir and permit definitive studies of HIV latency. When radiation or busulfan-conditioned, immune-deficient NSG mice are transplanted with human hematopoietic stem cells, human cells from the bone marrow enter the brain and differentiate to express microglia-specific markers. After infection with replication competent HIV, virus was detected in these bone marrow-derived human microglia. Studies of HIV latency in this model would be greatly enhanced by the development of compounds that can selectively reverse HIV latency in microglial cells. Our studies have identified members of the CoREST repression complex as key regulators of HIV latency in microglia in both rat and human microglial cell lines. The monoamine oxidase (MAO) and potential CoREST inhibitor, phenelzine, which is brain penetrant, was able to stimulate HIV production in human microglial cell lines and human glial cells recovered from the brains of HIV-infected humanized mice. The humanized mice we have developed therefore show great promise as a model system for the development of strategies aimed at defining and reducing the CNS reservoir.
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Affiliation(s)
- George N Llewellyn
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - David Alvarez-Carbonell
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Morgan Chateau
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA.
| | - Paula M Cannon
- Department of Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA.
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6
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Sagar V, Pilakka-Kanthikeel S, Martinez PC, Atluri VSR, Nair M. Common gene-network signature of different neurological disorders and their potential implications to neuroAIDS. PLoS One 2017; 12:e0181642. [PMID: 28792504 PMCID: PMC5549695 DOI: 10.1371/journal.pone.0181642] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 07/05/2017] [Indexed: 12/22/2022] Open
Abstract
The neurological complications of AIDS (neuroAIDS) during the infection of human immunodeficiency virus (HIV) are symptomized by non-specific, multifaceted neurological conditions and therefore, defining a specific diagnosis/treatment mechanism(s) for this neuro-complexity at the molecular level remains elusive. Using an in silico based integrated gene network analysis we discovered that HIV infection shares convergent gene networks with each of twelve neurological disorders selected in this study. Importantly, a common gene network was identified among HIV infection, Alzheimer's disease, Parkinson's disease, multiple sclerosis, and age macular degeneration. An mRNA microarray analysis in HIV-infected monocytes showed significant changes in the expression of several genes of this in silico derived common pathway which suggests the possible physiological relevance of this gene-circuit in driving neuroAIDS condition. Further, this unique gene network was compared with another in silico derived novel, convergent gene network which is shared by seven major neurological disorders (Alzheimer's disease, Parkinson's disease, Multiple Sclerosis, Age Macular Degeneration, Amyotrophic Lateral Sclerosis, Vascular Dementia, and Restless Leg Syndrome). These networks differed in their gene circuits; however, in large, they involved innate immunity signaling pathways, which suggests commonalities in the immunological basis of different neuropathogenesis. The common gene circuits reported here can provide a prospective platform to understand how gene-circuits belonging to other neuro-disorders may be convoluted during real-time neuroAIDS condition and it may elucidate the underlying-and so far unknown-genetic overlap between HIV infection and neuroAIDS risk. Also, it may lead to a new paradigm in understanding disease progression, identifying biomarkers, and developing therapies.
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Affiliation(s)
- Vidya Sagar
- Institute of Neuroimmune Pharmacology/Center for Personalized Nanomedicine, Department of Immunology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
| | - S. Pilakka-Kanthikeel
- Institute of Neuroimmune Pharmacology/Center for Personalized Nanomedicine, Department of Immunology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
| | - Paola C. Martinez
- Institute of Neuroimmune Pharmacology/Center for Personalized Nanomedicine, Department of Immunology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
| | - V. S. R. Atluri
- Institute of Neuroimmune Pharmacology/Center for Personalized Nanomedicine, Department of Immunology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
| | - M. Nair
- Institute of Neuroimmune Pharmacology/Center for Personalized Nanomedicine, Department of Immunology, Herbert Wertheim College of Medicine, Florida International University, Miami, Florida, United States of America
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7
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Levast B, Barblu L, Coutu M, Prévost J, Brassard N, Peres A, Stegen C, Madrenas J, Kaufmann DE, Finzi A. HIV-1 gp120 envelope glycoprotein determinants for cytokine burst in human monocytes. PLoS One 2017; 12:e0174550. [PMID: 28346521 PMCID: PMC5367833 DOI: 10.1371/journal.pone.0174550] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 03/10/2017] [Indexed: 11/26/2022] Open
Abstract
The first step of HIV infection involves the interaction of the gp120 envelope glycoprotein to its receptor CD4, mainly expressed on CD4+ T cells. Besides its role on HIV-1 entry, the gp120 has been shown to be involved in the production of IL-1, IL-6, CCL20 and other innate response cytokines by bystander, uninfected CD4+ T cells and monocytes. However, the gp120 determinants involved in these functions are not completely understood. Whether signalling leading to cytokine production is due to CD4 or other receptors is still unclear. Enhanced chemokine receptor binding and subsequent clustering receptors may lead to cytokine production. By using a comprehensive panel of gp120 mutants, here we show that CD4 binding is mandatory for cytokine outburst in monocytes. Our data suggest that targeting monocytes in HIV-infected patients might decrease systemic inflammation and the potential tissue injury associated with the production of inflammatory cytokines. Understanding how gp120 mediates a cytokine burst in monocytes might help develop new approaches to improve the chronic inflammation that persists in these patients despite effective suppression of viremia by antiretroviral therapy.
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Affiliation(s)
- Benoît Levast
- Department of Microbiology and Immunology, and Microbiome and Disease Tolerance Centre, McGill University, Montreal, Quebec, Canada
| | - Lucie Barblu
- Centre de Recherche du Centre Hospitalier Universitaire de Montréal, Montreal, Quebec, Canada
| | - Mathieu Coutu
- Centre de Recherche du Centre Hospitalier Universitaire de Montréal, Montreal, Quebec, Canada
| | - Jérémie Prévost
- Centre de Recherche du Centre Hospitalier Universitaire de Montréal, Montreal, Quebec, Canada
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, Quebec, Canada
| | - Nathalie Brassard
- Centre de Recherche du Centre Hospitalier Universitaire de Montréal, Montreal, Quebec, Canada
| | - Adam Peres
- Department of Microbiology and Immunology, and Microbiome and Disease Tolerance Centre, McGill University, Montreal, Quebec, Canada
| | - Camille Stegen
- Department of Microbiology and Immunology, and Microbiome and Disease Tolerance Centre, McGill University, Montreal, Quebec, Canada
| | - Joaquín Madrenas
- Department of Microbiology and Immunology, and Microbiome and Disease Tolerance Centre, McGill University, Montreal, Quebec, Canada
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Daniel E. Kaufmann
- Centre de Recherche du Centre Hospitalier Universitaire de Montréal, Montreal, Quebec, Canada
- Department of Medicine, Université de Montréal, Montreal, Quebec, Canada
| | - Andrés Finzi
- Department of Microbiology and Immunology, and Microbiome and Disease Tolerance Centre, McGill University, Montreal, Quebec, Canada
- Centre de Recherche du Centre Hospitalier Universitaire de Montréal, Montreal, Quebec, Canada
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, Quebec, Canada
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8
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HIV-1 increases TLR responses in human primary astrocytes. Sci Rep 2015; 5:17887. [PMID: 26671458 PMCID: PMC4680863 DOI: 10.1038/srep17887] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/09/2015] [Indexed: 12/12/2022] Open
Abstract
Astrocytes are the major glial cell within the central nervous system and have a number of important physiological properties related to brain homeostasis. They provide trophic support to neurons and are immune cells with key roles during states-of-inflammation. The potential for production of proinflammatory cytokines and its consequences has been studied in the context of HIV-1 infection of normal human astrocytes (NHA). NHA express TLR3, TLR4, and TLR5. TLR3 ligation induced the strongest proinflammatory polarizing response, characterized by generation of high levels of TNF-α, IL-6, and IL-8. HIV-1 increased the transient production of key inflammatory mediators, and exposure to LPS of HIV-1-infected cells increased significantly the cytokine secretion. We confirmed that it is necessary viral gene expression from the moment of pretreatment with antiretrovirals inhibited totally HIV-1-induced TLR response. The higher response to LPS from HIV-1-infected cells did not correlate with TLR4 or MyD88 increased expression. LPS responsiveness of infected cells parallels MHC class II expression, but not CD14. HIV-1-infected NHA present increased sensitivity to the proinflammatory effects of LPS. If this phenomenon occurs in vivo, it will contribute to the immunopathogenesis of this disease and may ultimately offer novel targets for immunomodulatory therapy.
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Expression of CHRFAM7A and CHRNA7 in neuronal cells and postmortem brain of HIV-infected patients: considerations for HIV-associated neurocognitive disorder. J Neurovirol 2015; 22:327-35. [PMID: 26567012 DOI: 10.1007/s13365-015-0401-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 10/13/2015] [Accepted: 10/27/2015] [Indexed: 10/22/2022]
Abstract
Despite the recent advances in antiretroviral therapy, human immunodeficiency virus type 1 (HIV-1) remains a global health threat. HIV-1 affects the central nervous system by releasing viral proteins that trigger neuronal death and neuroinflammation, and promotes alterations known as HIV-associated neurocognitive disorders (HAND). This disorder is not fully understood, and no specific treatments are available. Recently, we demonstrated that the HIV-1 envelope protein gp120IIIB induces a functional upregulation of the α7-nicotinic acetylcholine receptor (α7) in neuronal cells. Furthermore, this upregulation promotes cell death that can be abrogated with receptor antagonists, suggesting that α7 may play an important role in the development of HAND. The partial duplication of the gene coding for the α7, known as CHRFAM7A, negatively regulates α7 expression but its role in HIV infection has not been studied. Hence, we studied both CHRNA7 and CHRFAM7A regulation patterns in various gp120IIIB in vitro conditions. In addition, we measured CHRNA7 and CHRFAM7A expression levels in postmortem brain samples from patients suffering from different stages of HAND. Our results demonstrate the induction of CHRNA7 expression accompanied by a significant downregulation of CHRFAM7A in neuronal cells when exposed to pathophysiological concentrations of gp120IIIB. Our results suggest a dysregulation of CHRFAM7A and CHRNA7 expressions in the basal ganglia from postmortem brain samples of HIV+ subjects and expand the current knowledge about the consequences of HIV infection in the brain.
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10
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Viral Infection of the Central Nervous System and Neuroinflammation Precede Blood-Brain Barrier Disruption during Japanese Encephalitis Virus Infection. J Virol 2015; 89:5602-14. [PMID: 25762733 DOI: 10.1128/jvi.00143-15] [Citation(s) in RCA: 166] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 03/02/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Japanese encephalitis is an acute zoonotic, mosquito-borne disease caused by Japanese encephalitis virus (JEV). Japanese encephalitis is characterized by extensive inflammation in the central nervous system (CNS) and disruption of the blood-brain barrier (BBB). However, the pathogenic mechanisms contributing to the BBB disruption are not known. Here, using a mouse model of intravenous JEV infection, we show that virus titers increased exponentially in the brain from 2 to 5 days postinfection. This was accompanied by an early, dramatic increase in the level of inflammatory cytokines and chemokines in the brain. Enhancement of BBB permeability, however, was not observed until day 4, suggesting that viral entry and the onset of inflammation in the CNS occurred prior to BBB damage. In vitro studies revealed that direct infection with JEV could not induce changes in the permeability of brain microvascular endothelial cell monolayers. However, brain extracts derived from symptomatic JEV-infected mice, but not from mock-infected mice, induced significant permeability of the endothelial monolayer. Consistent with a role for inflammatory mediators in BBB disruption, the administration of gamma interferon-neutralizing antibody ameliorated the enhancement of BBB permeability in JEV-infected mice. Taken together, our data suggest that JEV enters the CNS, propagates in neurons, and induces the production of inflammatory cytokines and chemokines, which result in the disruption of the BBB. IMPORTANCE Japanese encephalitis (JE) is the leading cause of viral encephalitis in Asia, resulting in 70,000 cases each year, in which approximately 20 to 30% of cases are fatal, and a high proportion of patients survive with serious neurological and psychiatric sequelae. Pathologically, JEV infection causes an acute encephalopathy accompanied by BBB dysfunction; however, the mechanism is not clear. Thus, understanding the mechanisms of BBB disruption in JEV infection is important. Our data demonstrate that JEV gains entry into the CNS prior to BBB disruption. Furthermore, it is not JEV infection per se, but the inflammatory cytokines/chemokines induced by JEV infection that inhibit the expression of TJ proteins and ultimately result in the enhancement of BBB permeability. Neutralization of gamma interferon (IFN-γ) ameliorated the enhancement of BBB permeability in JEV-infected mice, suggesting that IFN-γ could be a potential therapeutic target. This study would lead to identification of potential therapeutic avenues for the treatment of JEV infection.
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11
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Lisi L, Tramutola A, De Luca A, Navarra P, Dello Russo C. Modulatory effects of the CCR5 antagonist maraviroc on microglial pro-inflammatory activation elicited by gp120. J Neurochem 2011; 120:106-14. [PMID: 22017448 DOI: 10.1111/j.1471-4159.2011.07549.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Despite important clinical benefits of the highly active antiretroviral therapy, neurological disorders affect approximately 50% of AIDS patients. In the brain, infected microglia release pro-inflammatory mediators as well as human immunodeficiency virus type 1 (HIV-1) proteins, like the envelope protein gp120, that sustain inflammation and mediate neuronal damage. Gp120 allows the virus entry in the host cells via binding to the CD4 receptor together with a specific co-receptor (CCR5/CXCR4). The antiretroviral drug maraviroc is a CCR5 receptor antagonist, approved for the treatment of HIV-experienced patients. By interfering with a chemokine receptor, highly expressed in microglia, maraviroc has the potential to modulate their activation during HIV-1 infection. To test this hypothesis, primary cultures of rat cortical microglia were activated by gp120. Gp120(CN54) , a protein derived by macrophage (M)-tropic viruses, showed strong pro-inflammatory action, thus it was used to test the effects of maraviroc. The latter displayed opposite effects, depending on whether or not interferon-γ (IFNγ) was also present in the system. IFNγ significantly enhanced gp120 proinflammatory activity, possibly via up-regulation of CCR5 receptor expression. In this experimental paradigm, maraviroc significantly increased microglial activation, thus suggesting that its chronic use can exacerbate neuronal pathology, especially in HIV-experienced patients with higher cerebral IFNγ levels.
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Affiliation(s)
- Lucia Lisi
- Institute of Pharmacology, Catholic University Medical School, Rome, Italy
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12
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Testa MP, Alvarado O, Wournell A, Lee J, Guilford FT, Henriksen SH, Phillips TR. Screening assay for oxidative stress in a feline astrocyte cell line, G355-5. J Vis Exp 2011:e2841. [PMID: 21775965 DOI: 10.3791/2841] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
An often-suggested mechanism of virus induced neuronal damage is oxidative stress. Astrocytes have an important role in controlling oxidative stress of the Central Nervous System (CNS). Astrocytes help maintain a homeostatic environment for neurons as well as protecting neurons from Reactive Oxygen Species (ROS). CM-H2DCFDA is a cell-permeable indicator for the presence of ROS. CM-H(2)DCFDA enters the cell as a non-fluorescent compound, and becomes fluorescent after cellular esterases remove the acetate groups, and the compound is oxidized. The number of cells, measured by flow cytometry, that are found to be green fluorescing is an indication of the number of cells that are in an oxidative state. CM-H(2)DCFDA is susceptible to oxidation by a large number of different ROS. This lack of specificity, regarding which ROS can oxidize CM-H(2)DCFDA, makes this compound a valuable regent for use in the early stages of a pathogenesis investigation, as this assay can be used to screen for an oxidative cellular environment regardless of which oxygen radical or combination of ROS are responsible for the cellular conditions. Once it has been established that ROS are present by oxidation of CM-H(2)DCFDA, then additional experiments can be performed to determine which ROS or combination of ROSs are involved in the particular pathogenesis process. The results of this study demonstrate that with the addition of hydrogen peroxide an increase in CM-H(2)DCFDA fluorescence was detected relative to the saline controls, indicating that this assay is a valuable test for detecting an oxidative environment within G355-5 cells, a feline astrocyte cell line.
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Affiliation(s)
- Maria Pia Testa
- College of Veterinary Medicine, Western University of Health Sciences, USA
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Shah A, Verma AS, Patel KH, Noel R, Rivera-Amill V, Silverstein PS, Chaudhary S, Bhat HK, Stamatatos L, Singh DP, Buch S, Kumar A. HIV-1 gp120 induces expression of IL-6 through a nuclear factor-kappa B-dependent mechanism: suppression by gp120 specific small interfering RNA. PLoS One 2011; 6:e21261. [PMID: 21712995 PMCID: PMC3119684 DOI: 10.1371/journal.pone.0021261] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Accepted: 05/25/2011] [Indexed: 12/21/2022] Open
Abstract
In addition to its role in virus entry, HIV-1 gp120 has also been implicated in HIV-associated neurocognitive disorders. However, the mechanism(s) responsible for gp120-mediated neuroinflammation remain undefined. In view of increased levels of IL-6 in HIV-positive individuals with neurological manifestations, we sought to address whether gp120 is involved in IL-6 over-expression in astrocytes. Transfection of a human astrocyte cell line with a plasmid encoding gp120 resulted in increased expression of IL-6 at the levels of mRNA and protein by 51.3±2.1 and 11.6±2.2 fold respectively; this effect of gp120 on IL-6 expression was also demonstrated using primary human fetal astrocytes. A similar effect on IL-6 expression was observed when primary astrocytes were treated with gp120 protein derived from different strains of X4 and R5 tropic HIV-1. The induction of IL-6 could be abrogated by use of gp120-specific siRNA. Furthermore, this study showed that the NF-κB pathway is involved in gp120-mediated IL-6 over-expression, as IKK-2 and IKKβ inhibitors inhibited IL-6 expression by 56.5% and 60.8%, respectively. These results were also confirmed through the use of NF-κB specific siRNA. We also showed that gp120 could increase the phosphorylation of IκBα. Furthermore, gp120 transfection in the SVGA cells increased translocation of NF-κB from cytoplasm to nucleus. These results demonstrate that HIV-1 gp120-mediated over-expression of IL-6 in astrocytes is one mechanism responsible for neuroinflammation in HIV-infected individuals and this is mediated by the NF-κB pathway.
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Affiliation(s)
- Ankit Shah
- Division of Pharmacology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
| | - Ashish S. Verma
- Division of Pharmacology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
| | - Kalpeshkumar H. Patel
- Division of Pharmacology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
| | | | | | - Peter S. Silverstein
- Division of Pharmacology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
| | | | - Hari K. Bhat
- Division of Pharmacology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
| | - Leonidas Stamatatos
- Seattle Biomedical Research Institute, Seattle, Washington, United States of America
| | - Dhirendra P. Singh
- University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Shilpa Buch
- University of Nebraska Medical Center, Omaha, Nebraska, United States of America
| | - Anil Kumar
- Division of Pharmacology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, United States of America
- * E-mail:
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Chen CJ, Ou YC, Chang CY, Pan HC, Liao SL, Raung SL, Chen SY. TNF-α and IL-1β mediate Japanese encephalitis virus-induced RANTES gene expression in astrocytes. Neurochem Int 2010; 58:234-42. [PMID: 21167894 DOI: 10.1016/j.neuint.2010.12.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 12/04/2010] [Accepted: 12/08/2010] [Indexed: 01/20/2023]
Abstract
Infection with Japanese encephalitis virus (JEV) causes neuroinfection and neuroinflammation characterized by profound neuronal destruction/dysfunction, concomitant microgliosis/astrogliosis, and production of various molecules that initiate the recruitment of immune cells to the sites of infection. Previously, we reported that glial cells expressed RANTES (regulated upon activation, normal T cell expressed and secreted) with chemotactic activity in response to JEV infection. In this study, we further demonstrated that JEV-infected microglia had an additional activity in regulating RANTES production. Both astrocytes and microglia responded to JEV infection by releasing RANTES through a process likely related to viral replication. Independent of infectious virus, supernatants of JEV-infected microglia, but not JEV-infected astrocytes, caused additional RANTES production from astrocytes. Antibody neutralization studies suggested the potential involvement of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in mediating additional RANTES production. Treatment of astrocyte cultures with TNF-α and IL-1β caused activation of several signaling molecules and transcription factors crucial to RANTES gene expression, including reactive oxygen species, extracellular signal-regulated kinase, NF-κB, and NF-IL6, increased RANTES gene promoter activity, and provoked RANTES production. As with RANTES, neutralization of bioactive TNF-α and IL-1β caused an attenuation of chemotactic activity from supernatants of mixed glia containing astrocytes and microglia during the course of JEV infection. In conclusion, TNF-α and IL-1β produced by JEV-infected microglia might trigger another mechanism which induces a secondary wave of RANTES gene expression by activating astrocytes. The released RANTES from glial cells might play a role in the recruitment of immune cells during JEV infection.
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Affiliation(s)
- Chun-Jung Chen
- Department of Education and Research, Taichung Veterans General Hospital, Taichung 407, Taiwan.
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15
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Bokhari SM, Yao H, Bethel-Brown C, Fuwang P, Williams R, Dhillon NK, Hegde R, Kumar A, Buch SJ. Morphine enhances Tat-induced activation in murine microglia. J Neurovirol 2010; 15:219-28. [PMID: 19462331 DOI: 10.1080/13550280902913628] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
There is increasing evidence that opiates accelerate the pathogenesis and progression of acquired immunodeficiency syndrome (AIDS), as well as the incidence of human immunodeficiency virus (HIV) encephalitis (HIVE), a condition characterized by inflammation, leukocyte infiltration, and microglial activation. The mechanisms, by which the HIV-1 transactivating protein Tat and opioids exacerbate microglial activation, however, are not fully understood. In the current study, we explored the effects of morphine and HIV-1 Tat(1-72) on the activation of mouse BV-2 microglial cells and primary mouse microglia. Both morphine and Tat exposure caused up-regulation of the chemokine receptor CCR5, an effect blocked by the opioid receptor antagonist naltrexone. Morphine in combination with Tat also induced morphological changes in the BV-2 microglia from a quiescent to an activated morphology, with a dramatic increase in the expression of the microglial activation marker CD11b, as compared with cells exposed to either agent alone. In addition, the mRNA expression of inducible nitric oxide synthase (iNOS), CD40 ligand, Interferon-gamma-inducible protein 10 (IP-10), and the proinflammatory cytokines tumor necrosis factor alpha (TNFalpha), interleukin (IL)-1beta, and IL-6, which were elevated with Tat alone, were dramatically enhanced with Tat in the presence of morphine. In summary, these findings shed light on the cooperative effects of morphine and HIV-1 Tat on both microglial activation and HIV coreceptor up-regulation, effects that could result in exacerbated neuropathogenesis.
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Affiliation(s)
- Sirosh M Bokhari
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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16
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Fitting S, Zou S, Chen W, Vo P, Hauser KF, Knapp PE. Regional heterogeneity and diversity in cytokine and chemokine production by astroglia: differential responses to HIV-1 Tat, gp120, and morphine revealed by multiplex analysis. J Proteome Res 2010; 9:1795-804. [PMID: 20121167 DOI: 10.1021/pr900926n] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
HIV-infected individuals who abuse opiates show a faster progression to AIDS and higher incidence of encephalitis. The HIV-1 proteins Tat and gp120 have been shown to cause neurodegenerative changes either in vitro or when injected or expressed in the CNS, and we have shown that opiate drugs can exacerbate neurotoxic effects in the striatum through direct actions on pharmacologically discrete subpopulations of mu-opioid receptor-expressing astroglia. Opiate coexposure also significantly enhances release of specific inflammatory mediators by astroglia from the striatum, and we theorize that astroglial reactivity may underlie aspects of HIV neuropathology. To determine whether astroglia from different regions of the central nervous system have distinct, intrinsic responses to HIV-1 proteins and opiates, we used multiplex suspension array analyses to define and compare the inflammatory signature of cytokines released by murine astrocytes grown from cerebral cortex, cerebellum, and spinal cord. Results demonstrate significant regional differences in baseline secretion patterns, and in responses to viral proteins. Of importance for the disease process, astrocytes from all regions have very limited inflammatory response to gp120 protein, as compared to Tat protein, either in the presence or absence of morphine. Overall, the chemokine/cytokine release is higher from spinal cord and cortical astroglia than from cerebellar astroglia, paralleling the relatively low incidence of HIV-related neuropathology in the cerebellum.
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Affiliation(s)
- Sylvia Fitting
- Department of Anatomy and Neurobiology, Department of Pharmacology and Toxicology, and Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, Virginia 23298-0709, USA
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Hahn YK, Vo P, Fitting S, Block ML, Hauser KF, Knapp PE. beta-Chemokine production by neural and glial progenitor cells is enhanced by HIV-1 Tat: effects on microglial migration. J Neurochem 2010; 114:97-109. [PMID: 20403075 PMCID: PMC2992981 DOI: 10.1111/j.1471-4159.2010.06744.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Human immunodeficiency virus (HIV)-1 neuropathology results from collective effects of viral proteins and inflammatory mediators on several cell types. Significant damage is mediated indirectly through inflammatory conditions promulgated by glial cells, including microglia that are productively infected by HIV-1, and astroglia. Neural and glial progenitors exist in both developing and adult brains. To determine whether progenitors are targets of HIV-1, a multi-plex assay was performed to assess chemokine/cytokine expression after treatment with viral proteins transactivator of transcription (Tat) or glycoprotein 120 (gp120). In the initial screen, ten analytes were basally released by murine striatal progenitors. The beta-chemokines CCL5/regulated upon activation, normal T cell expressed and secreted, CCL3/macrophage inflammatory protein-1alpha, and CCL4/macrophage inflammatory protein-1beta were increased by 12-h exposure to HIV-1 Tat. Secreted factors from Tat-treated progenitors were chemoattractive towards microglia, an effect blocked by 2D7 anti-CCR5 antibody pre-treatment. Tat and opiates have interactive effects on astroglial chemokine secretion, but this interaction did not occur in progenitors. gp120 did not affect chemokine/cytokine release, although both CCR5 and CXCR4, which serve as gp120 co-receptors, were detected in progenitors. We postulate that chemokine production by progenitors may be a normal, adaptive process that encourages immune inspection of newly generated cells. Pathogens such as HIV might usurp this function to create a maladaptive state, especially during development or regeneration, when progenitors are numerous.
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Affiliation(s)
- Yun Kyung Hahn
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA 23298 USA
| | - Phu Vo
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298 USA
| | - Sylvia Fitting
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298 USA
| | - Michelle L. Block
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA 23298 USA
| | - Kurt F. Hauser
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298 USA
- Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA 23298 USA
| | - Pamela E. Knapp
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA 23298 USA
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298 USA
- Institute for Drug and Alcohol Studies, Virginia Commonwealth University, Richmond, VA 23298 USA
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18
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Chen CJ, Ou YC, Lin SY, Raung SL, Liao SL, Lai CY, Chen SY, Chen JH. Glial activation involvement in neuronal death by Japanese encephalitis virus infection. J Gen Virol 2010; 91:1028-1037. [DOI: 10.1099/vir.0.013565-0] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/29/2023] Open
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19
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Evidence Group I mGluR Drugs Modulate the Activation Profile of Lipopolysaccharide-Exposed Microglia in Culture. Neurochem Res 2009; 34:1721-8. [DOI: 10.1007/s11064-009-9999-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2009] [Accepted: 05/14/2009] [Indexed: 11/25/2022]
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20
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Ronaldson PT, Persidsky Y, Bendayan R. Regulation of ABC membrane transporters in glial cells: Relevance to the pharmacotherapy of brain HIV-1 infection. Glia 2008; 56:1711-35. [DOI: 10.1002/glia.20725] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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21
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Liner KJ, Hall CD, Robertson KR. Impact of human immunodeficiency virus (HIV) subtypes on HIV-associated neurological disease. J Neurovirol 2007; 13:291-304. [PMID: 17849313 DOI: 10.1080/13550280701422383] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Among the many variables affecting transmission and pathogenesis of the human immunodeficiency virus type 1(HIV-1), the effects of HIV subtypes, or clades, on disease progression remain unclear. Although debated, some studies have found that the variable env and pol sequences of different subtypes of HIV-1 may endow some subtypes with greater degrees of cell tropism, virulence, and drug resistance, which may lead to differences in overall disease progression. HIV-associated dementia (HAD) appears to be associated with viral diversity and markers of immune activation. Africa has the highest prevalence of HIV, largest viral diversity, and is where clade recombination occurs most frequently. All of these factors would suggest that HAD would pose the largest threat in this region of the world. Although investigations into the effects of different subtypes on overall disease progression are well documented, few have looked into the effects of subtypes on neurological disease progression. This review highlights the need for more international research involving the neurological effects and especially the clinical presentation of dementia for the entire range of the group M HIV-1 subtypes.
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Affiliation(s)
- Kevin J Liner
- Department of Neurology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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22
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Yang CS, Lee HM, Lee JY, Kim JA, Lee SJ, Shin DM, Lee YH, Lee DS, El-Benna J, Jo EK. Reactive oxygen species and p47phox activation are essential for the Mycobacterium tuberculosis-induced pro-inflammatory response in murine microglia. J Neuroinflammation 2007; 4:27. [PMID: 18036262 PMCID: PMC2235845 DOI: 10.1186/1742-2094-4-27] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Accepted: 11/26/2007] [Indexed: 01/09/2023] Open
Abstract
Background Activated microglia elicits a robust amount of pro-inflammatory cytokines, which are implicated in the pathogenesis of tuberculosis in the central nervous system (CNS). However, little is known about the intracellular signaling mechanisms governing these inflammatory responses in microglia in response to Mycobacterium tuberculosis (Mtb). Methods Murine microglial BV-2 cells and primary mixed glial cells were stimulated with sonicated Mtb (s-Mtb). Intracellular ROS levels were measured by staining with oxidative fluorescent dyes [2',7'-Dichlorodihydrofluorescein diacetate (H2DCFDA) and dihydroethidium (DHE)]. NADPH oxidase activities were measured by lucigenin chemiluminescence assay. S-Mtb-induced MAPK activation and pro-inflammatory cytokine release in microglial cells were measured using by Western blot analysis and enzyme-linked immunosorbent assay, respectively. Results We demonstrate that s-Mtb promotes the up-regulation of reactive oxygen species (ROS) and the rapid activation of mitogen-activated protein kinases (MAPKs), including p38 and extracellular signal-regulated kinase (ERK) 1/2, as well as the secretion of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-12p40 in murine microglial BV-2 cells and primary mixed glial cells. Both NADPH oxidase and mitochondrial electron transfer chain subunit I play an indispensable role in s-Mtb-induced MAPK activation and pro-inflammatory cytokine production in BV-2 cells and mixed glial cells. Furthermore, the activation of cytosolic NADPH oxidase p47phox and MAPKs (p38 and ERK1/2) is mutually dependent on s-Mtb-induced inflammatory signaling in murine microglia. Neither TLR2 nor dectin-1 was involved in s-Mtb-induced inflammatory responses in murine microglia. Conclusion These data collectively demonstrate that s-Mtb actively induces the pro-inflammatory response in microglia through NADPH oxidase-dependent ROS generation, although the specific pattern-recognition receptors involved in these responses remain to be identified.
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Affiliation(s)
- Chul-Su Yang
- Department of Microbiology, College of Medicine, Chungnam National University, Daejeon 301-747, S. Korea.
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23
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Schoeniger-Skinner DK, Ledeboer A, Frank MG, Milligan ED, Poole S, Martin D, Maier SF, Watkins LR. Interleukin-6 mediates low-threshold mechanical allodynia induced by intrathecal HIV-1 envelope glycoprotein gp120. Brain Behav Immun 2007; 21:660-7. [PMID: 17204394 PMCID: PMC1991283 DOI: 10.1016/j.bbi.2006.10.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 10/11/2006] [Accepted: 10/20/2006] [Indexed: 12/20/2022] Open
Abstract
Spinal cord glia (microglia and astrocytes) contribute to enhanced pain states. One model that has been used to study this phenomenon is intrathecal (i.t.) administration of gp120, an envelope glycoprotein of HIV-1 known to activate spinal cord glia and thereby induce low-threshold mechanical allodynia, a pain symptom where normally innocuous (non-painful) stimuli are perceived as painful. Previous studies have shown that i.t. gp120-induced allodynia is mediated via the release of the glial pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF), and interleukin-1beta (IL-1). As we have recently reported that i.t. gp120 induces the release of interleukin-6 (IL-6), in addition to IL-1 and TNF, the present study tested whether this IL-6 release in spinal cord contributes to gp120-induced mechanical allodynia and/or to gp120-induced increases in TNF and IL-1. An i.t. anti-rat IL-6 neutralizing antibody was used to block IL-6 actions upon its release by i.t. gp120. This IL-6 blockade abolished gp120-induced mechanical allodynia. While the literature predominantly documents the cascade of pro-inflammatory cytokines as beginning with TNF, followed by the stimulation of IL-1, and finally TNF plus IL-1 stimulating the release of IL-6, the present findings indicate that a blockade of IL-6 inhibits the gp120-induced elevations of TNF, IL-1, and IL-6 mRNA in dorsal spinal cord, elevation of IL-1 protein in lumbar dorsal spinal cord, and TNF and IL-1 protein release into the surrounding lumbosacral cerebrospinal fluid. These results would suggest that IL-6 induces pain facilitation, and may do so in part by stimulating the production and release of other pro-inflammatory cytokines.
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Affiliation(s)
- Diana K. Schoeniger-Skinner
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
| | - Annemarie Ledeboer
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
| | - Matthew G. Frank
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
| | - Erin D. Milligan
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
| | - Stephen Poole
- Division of Endocrinology, National Institute for Biological Standards and Control, South Mimms, Potters Bar, Herts Eng 3QG, United Kingdom
| | - David Martin
- Department of Pharmacology, Amgen, Thousand Oaks, CA 91320
| | - Steven F. Maier
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
| | - Linda R. Watkins
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309
- # To whom correspondence should be addressed: Department of Psychology, Muenzinger D-244, Campus Box 345, University of Colorado at Boulder, Boulder, CO 30809-0345, Ph: 303-492-7034, Fax: 303-492-2967,
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Human immunodeficiency virus type 1 efficiently binds to human fetal astrocytes and induces neuroinflammatory responses independent of infection. BMC Neurosci 2007; 8:31. [PMID: 17498309 PMCID: PMC1884168 DOI: 10.1186/1471-2202-8-31] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Accepted: 05/12/2007] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND HIV-1 infects human astrocytes in vitro and in vivo but the frequency of infected cells is low and its biological significance is unknown. In studies in vitro, recombinant gp120 alone can induce profound effects on astrocyte biology, suggesting that HIV-1 interaction with astrocytes and its functional consequences extend beyond the limited levels of infection in these cells. Here we determined the relative efficiencies of HIV-1 binding and infection in human fetal astrocytes (HFA), mainly at the single cell level, using HIV-1 tagged with green fluorescence protein (GFP)-Vpr fusion proteins, termed HIV-GFP, to detect virus binding and HIV-1 expressing Rev and NefGFP fusion proteins to detect productive infection. RESULTS Essentially all HFA in a population bound HIV-GFP specifically and independently of CCR5 and CXCR4. The dynamics of this binding at 37 degrees C resembled binding of an HIV fusion mutant to CD4-positive cells, indicating that most of HIV-GFP arrested infection of HFA at the stage of virus-cell fusion. Despite extensive binding, only about 1% of HFA were detectably infected by HIV-RevGFP or HIV-NefGFP, but this proportion increased to the majority of HFA when the viruses were pseudotyped with vesicular stomatitis virus envelope glycoprotein G, confirming that HFA impose a restriction upon HIV-1 entry. Exposure of HFA to HIV-1 through its native proteins rapidly induced synthesis of interleukin-6 and interleukin-8 with increased mRNA detected within 3 h and increased protein detected within 18 h of exposure. CONCLUSION Our results indicate that HIV-1 binding to human astrocytes, although extensive, is not generally followed by virus entry and replication. Astrocytes respond to HIV-1 binding by rapidly increased cytokine production suggesting a role of this virus-brain cell interaction in HIV-1 neuropathogenesis.
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Yano M, Nakamuta S, Shiota M, Endo H, Kido H. Gatekeeper role of 14-3-3tau protein in HIV-1 gp120-mediated apoptosis of human endothelial cells by inactivation of Bad. AIDS 2007; 21:911-20. [PMID: 17457084 DOI: 10.1097/qad.0b013e32810539f3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE HIV-1-associated dementia (HAD) is a major neurological complication often observed in the advanced stages of AIDS. We have reported that 14-3-3 proteins in cerebrospinal fluid, reflecting neuronal cell destruction, is a real-time marker of HAD progression. This study was designed to examine the role of 14-3-3 proteins in HAD. DESIGN An in-vitro human umbilical vein endothelial cells (HUVEC) model of gp120 protein-induced apoptosis to study the protective role of 14-3-3 in HIV-1 gp120/CXCR4-mediated cell death. METHODS The alpha-chemokine receptor-mediated cell death by HIV-1 envelope protein, gp120, the critical event that causes neuron loss and endothelial cell injury, was evaluated in HUVEC undergoing gp120-induced apoptosis through the CXCR4 receptor. We studied the effects of siRNA for each 14-3-3 isoform on the death of HUVEC treated with CXCR4-preferring gp120 (IIIB). RESULTS Gp120 increased the expression of 14-3-3tau in HUVEC. The binding of Gp120 to CXCR4 induced apoptosis of HUVEC through decreased binding of 14-3-3tau to the pro-apoptotic molecule, Bad. Treatment of the cells with dsRNA against 14-3-3tau enhanced the gp120-mediated dephosphorylation of Bad and its association with Bcl-XL in mitochondria, accelerating the gp120-induced apoptosis, whereas suppression of Bad by RNAi rescued the cells from apoptosis triggered by gp120. CONCLUSIONS The specific up-regulation of 14-3-3tau in HUVEC negatively regulated gp120/CXCR4-mediated cell death by protecting Bad dephosphorylation.
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Affiliation(s)
- Mihiro Yano
- Division of Enzyme Chemistry, Institute for Enzyme Research, The University of Tokushima, Tokushima 770-8503, Japan
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26
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Block ML, Zecca L, Hong JS. Microglia-mediated neurotoxicity: uncovering the molecular mechanisms. Nat Rev Neurosci 2007; 8:57-69. [PMID: 17180163 DOI: 10.1038/nrn2038] [Citation(s) in RCA: 3003] [Impact Index Per Article: 176.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Mounting evidence indicates that microglial activation contributes to neuronal damage in neurodegenerative diseases. Recent studies show that in response to certain environmental toxins and endogenous proteins, microglia can enter an overactivated state and release reactive oxygen species (ROS) that cause neurotoxicity. Pattern recognition receptors expressed on the microglial surface seem to be one of the primary, common pathways by which diverse toxin signals are transduced into ROS production. Overactivated microglia can be detected using imaging techniques and therefore this knowledge offers an opportunity not only for early diagnosis but, importantly, for the development of targeted anti-inflammatory therapies that might slow or halt the progression of neurodegenerative disease.
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Affiliation(s)
- Michelle L Block
- Neuropharmacology Section, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
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27
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Kim YJ, Hwang SY, Oh ES, Oh S, Han IO. IL-1beta, an immediate early protein secreted by activated microglia, induces iNOS/NO in C6 astrocytoma cells through p38 MAPK and NF-kappaB pathways. J Neurosci Res 2006; 84:1037-46. [PMID: 16881054 DOI: 10.1002/jnr.21011] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In the present study we sought to examine cell-cell interactions by investigating the effects of factors released by stimulated microglia on inducible nitric oxide (NO) synthase (iNOS) induction in astrocytoma cells. After examining the temporal profiles of proinflammatory molecules induced by lipopolysaccharide (LPS) stimulation in BV2 microglial cells, iNOS and IL-1beta were observed to be the first immediate-response molecules. Removal of LPS after 3 hr stimulation abrogated NO release, whereas a full induction of IL-1beta was retained in BV2 cells. We observed consistently that conditioned medium (CM) from activated microglia resulted in the induction of iNOS in C6 cells, and IL-1beta was shown to be a key regulator of iNOS induction. An IL-1beta-neutralizing antibody diminished NO induction. Incubation with recombinant IL-1beta stimulated NO release to a lesser extent compared to microglial CM; co-treatment of LPS and IL-1beta had a potent, synergistic effect on NO release from C6 cells. Transient transfection with MEK kinase 1 (MEKK1) or nuclear factor-kappa B (NF-kappaB) expression plasmids induced iNOS, and IL-1beta further enhanced the MEKK1 response. Furthermore, IL-1beta-mediated NO release from C6 cells was significantly suppressed by inhibition of p38 mitogen activated protein kinase (MAPK) or NF-kappaB by specific chemical inhibitors. Both IL-1beta and MEKK1 stimulated p38 and JNK MAPKs, as well as the NF-kappaB pathway, to induce iNOS in C6 cells. Microglia may represent an anti-tumor response in the central nervous system, which is potentiated by the local secretion of immunomodulatory factors that in turn affects astrocytoma (glioma) cells. A better understanding of microglia-glioma or microglia-astrocyte interactions will help in the design of novel immune-based therapies for brain tumors or neuronal diseases.
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Affiliation(s)
- Yun-Jung Kim
- Department of Physiology and Biophysics, and Center for Advanced Medical Education by BK21 Project, Inha University, College of Medicine, Incheon, Korea
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Abstract
Many viruses cause encephalitis, but understanding the mechanisms by which viral infection leads to encephalopathy or dementia remain elusive. In many cases, inflammation generated by the host's attempt to combat the infection is itself implicated as a primary factor in causing neuronal dysfunction or degeneration. In this review, we outline the current state of knowledge regarding the pathophysiology of CNS (central nervous system) injury in viral infection. We focus our review on the neuropathogenesis of HIV type 1 (HIV-1)-associated dementia, because, within this class of infection, it is the best studied. We will also discuss the key similarities and differences in the pathological mechanisms of other important viral encephalitides. Understanding these mechanisms should ultimately enable development of immunomodulatory therapies for treating these infections, as well as other neuro-inflammatory conditions.
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Affiliation(s)
- Tongguang Wang
- Department of Neurology, Johns Hopkins University, 600 N. Wolfe St, Baltimore, MD 21287, USA
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29
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Ronaldson PT, Bendayan R. HIV-1 viral envelope glycoprotein gp120 triggers an inflammatory response in cultured rat astrocytes and regulates the functional expression of P-glycoprotein. Mol Pharmacol 2006; 70:1087-98. [PMID: 16790532 DOI: 10.1124/mol.106.025973] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In this work, we examined the ability of gp120, a human immunodeficiency virus-1 (HIV-1) viral envelope glycoprotein, to trigger the innate immune response in astrocytes, an HIV-1 brain cellular target, and we investigated the functional expression of the ATP-binding cassette membrane transporter P-glycoprotein (P-gp) in primary cultures of rat astrocytes treated with gp120 or cytokines [tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and IL-6]. Standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium and d-mannitol uptake assays confirmed that HIV-1(96ZM651) gp120 treatment did not alter cell viability or membrane permeability. Semiquantitative reverse-transcriptase polymerase chain reaction analysis and enzyme-linked immunosorbent assay demonstrated increased TNF-alpha, IL-1beta, and IL-6 mRNA and protein expression in cultures treated with HIV-1(96ZM651) gp120, suggesting in vitro activation of immune responses. Cytokine secretion was detected when CXCR4 but not CCR5 was inhibited with a specific antibody, implying that cytokine secretion is primarily mediated via CCR5 in astrocytes triggered with HIV-1(96ZM651) gp120. P-gp protein expression was increased in astrocyte cultures exposed to TNF-alpha (2.9-fold) or IL-1beta (1.6-fold) but was decreased profoundly in the presence of IL-6 (8.9-fold), suggesting that IL-6 is primarily involved in modulating P-gp expression. In parallel, after HIV-1(96ZM651) gp120 treatment, immunoblotting analysis showed a significant decrease in P-gp expression (4.7-fold). Furthermore, the accumulation of two P-gp substrates, digoxin and saquinavir (an HIV-1 protease inhibitor), was enhanced (1.5- to 1.8-fold) in HIV-1(96ZM651) gp120-treated astrocyte monolayers but was not altered by P-gp inhibitors [e.g., valspodar (PSC833) and elacridar (GF120918)], suggesting a loss of transport activity. Taken together, these data imply that HIV-1(96ZM651) gp120 or cytokine treatment modulate P-gp functional expression in astrocytes, which may lead to complex drug-transporter interactions during HIV-1 encephalitis-associated immune responses.
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Affiliation(s)
- Patrick T Ronaldson
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, 144 College Street, Toronto, ON, Canada, M5S 3M2
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Block ML, Hong JS. Microglia and inflammation-mediated neurodegeneration: multiple triggers with a common mechanism. Prog Neurobiol 2005; 76:77-98. [PMID: 16081203 DOI: 10.1016/j.pneurobio.2005.06.004] [Citation(s) in RCA: 1141] [Impact Index Per Article: 60.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Revised: 06/21/2005] [Accepted: 06/28/2005] [Indexed: 12/21/2022]
Abstract
Inflammation, a common denominator among the diverse list of neurodegenerative diseases, has recently been implicated as a critical mechanism responsible for the progressive nature of neurodegeneration. Microglia are the resident innate immune cells in the central nervous system and produce a barrage of factors (IL-1, TNFalpha, NO, PGE2, superoxide) that are toxic to neurons. Evidence supports that the unregulated activation of microglia in response to environmental toxins, endogenous proteins, and neuronal death results in the production of toxic factors that propagate neuronal injury. In the following review, we discuss the common thread of microglial activation across numerous neurodegenerative diseases, define current perceptions of how microglia are damaging neurons, and explain how the microglial response to neuronal damage results in a self-propelling cycle of neuron death.
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Affiliation(s)
- Michelle L Block
- Neuropharmacology Section, MD F1-01, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, NC 27709, USA.
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31
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Ledeboer A, Gamanos M, Lai W, Martin D, Maier SF, Watkins LR, Quan N. Involvement of spinal cord nuclear factor κB activation in rat models of proinflammatory cytokine-mediated pain facilitation. Eur J Neurosci 2005; 22:1977-86. [PMID: 16262636 DOI: 10.1111/j.1460-9568.2005.04379.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Proinflammatory cytokines, such as interleukin-1beta and tumour necrosis factor-alpha, are released by activated glial cells in the spinal cord and play a major role in pain facilitation. These cytokines exert their actions, at least partially, through the activation of the transcription factor, nuclear factor kappaB (NF-kappaB). In turn, NF-kappaB regulates the transcription of many inflammatory mediators, including cytokines. We have previously shown that intrathecal injection of the human immunodeficiency virus-1 (HIV-1) envelope glycoprotein, gp120, induces mechanical allodynia via the release of proinflammatory cytokines. Here, we investigated whether NF-kappaB is involved in gp120-induced pain behaviour in Sprague-Dawley rats. Intrathecal administration of NF-kappaB inhibitors, pyrrolidinedithiocarbamate (PDTC) and SN50, prior to gp120 partially attenuated gp120-induced allodynia. In addition, PDTC delayed and reversed allodynia in a model of neuropathic pain induced by sciatic nerve inflammation. These observations suggest that intrathecal gp120 may lead to activation of NF-kappaB within the spinal cord. To reveal NF-kappaB activation, we assessed inhibitory factor kappaBalpha (IkappaBalpha) mRNA expression by in situ hybridization, as NF-kappaB activation up-regulates IkappaBalpha gene expression as part of an autoregulatory feedback loop. No or low levels of IkappaBalpha mRNA were detected in the lumbar spinal cord of vehicle-injected rats, whereas IkappaBalpha mRNA expression was markedly induced in the spinal cord following intrathecal gp120 in predominantly astrocytes and endothelial cells. Moreover, IkappaBalpha mRNA expression positively correlated with proinflammatory cytokine protein levels in lumbosacral cerebrospinal fluid. Together, these results demonstrate that spinal cord NF-kappaB activation is involved, at least in part, in exaggerated pain states.
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Affiliation(s)
- Annemarie Ledeboer
- Department of Psychology & Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309-0345, USA.
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32
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Banks WA, Robinson SM, Nath A. Permeability of the blood–brain barrier to HIV-1 Tat. Exp Neurol 2005; 193:218-27. [PMID: 15817280 DOI: 10.1016/j.expneurol.2004.11.019] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2004] [Revised: 11/09/2004] [Accepted: 11/16/2004] [Indexed: 11/28/2022]
Abstract
Infection with human immunodeficiency virus-1 (HIV-1) is associated with dysfunctions of the central nervous system (CNS). HIV-1 induces its effects on the CNS by a variety of mechanisms, including by shedding the neurotoxic viral proteins such as gp120 and Tat. Both HIV-1 and gp120 have been shown to cross the blood-brain barrier (BBB). It is has not been determined, however, whether blood-borne Tat can cross the BBB. Here, we found that Tat crosses the BBB by a nonsaturable mechanism with a unidirectional influx rate of about 0.490 microl/g/min. About 0.126% of an intravenous dose of Tat enters each g of brain. Radioactively labeled albumin injected simultaneously did not cross the BBB. The hypothalamus, occipital cortex, and hippocampus were the regions of the brain most permeable to Tat. Nonsaturable brain-to-blood efflux also occurred, most likely with reabsorption into the blood of the cerebrospinal fluid. In conclusion, we found that Tat crossed the BBB bidirectionally. Such permeability could provide a mechanism by which Tat produced on one side of the BBB could affect neural or immune function on the other side.
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Affiliation(s)
- William A Banks
- Division of Geriatrics, Department of Internal Medicine, GRECC, Veterans Affairs Medical Center-St. Louis and Saint Louis University School of Medicine, 915 N. Grand Boulevard, St. Louis, MO 63106, USA.
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Abstract
Human immunodeficiency virus (HIV) infection is often complicated by the development of acquired immunodeficiency syndrome (AIDS) dementia complex (ADC). Quinolinic acid (QUIN) is an end product of tryptophan, metabolized through the kynurenine pathway (KP) that can act as an endogenous brain excitotoxin when produced and released by activated macrophages/microglia, the very cells that are prominent in the pathogenesis of ADC. This review examines QUIN's involvement in the features of ADC and its role in pathogenesis. We then synthesize these findings into a hypothetical model for the role played by QUIN in ADC, and discuss the implications of this model for ADC and other inflammatory brain diseases.
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Affiliation(s)
- Gilles J Guillemin
- Centre for Immunology, Department of Neurology, St Vincent's Hospital, Sydney, Australia
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Peterson KE, Hughes S, Dimcheff DE, Wehrly K, Chesebro B. Separate sequences in a murine retroviral envelope protein mediate neuropathogenesis by complementary mechanisms with differing requirements for tumor necrosis factor alpha. J Virol 2004; 78:13104-12. [PMID: 15542662 PMCID: PMC525006 DOI: 10.1128/jvi.78.23.13104-13112.2004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The innate immune response, through the induction of proinflammatory cytokines and antiviral factors, plays an important role in protecting the host from pathogens. Several components of the innate response, including tumor necrosis factor alpha (TNF-alpha), monocyte chemoattractant protein 1, interferon-inducible protein 10, and RANTES, are upregulated in the brain following neurovirulent retrovirus infection in humans and in animal models. However, it remains unclear whether this immune response is protective, pathogenic, or both. In the present study, by using TNF-alpha(-/-) mice we analyzed the contribution of TNF-alpha to neurological disease induced by four neurovirulent murine retroviruses, with three of these viruses encoding portions of the same neurovirulent envelope protein. Surprisingly, only one retrovirus (EC) required TNF-alpha for disease induction, and this virus induced less TNF-alpha expression in the brain than did the other retroviruses. Analysis of glial fibrillary acidic protein and F4/80 in EC-infected TNF-alpha(-/-) mice showed normal activation of astrocytes but not of microglia. Thus, TNF-alpha-mediated microglial activation may be important in the pathogenic process initiated by EC infection. In contrast, TNF-alpha was not required for pathogenesis of the closely related BE virus and the BE virus induced disease in TNF-alpha(-/-) mice by a different mechanism that did not require microglial activation. These results provide new insights into the multifactorial mechanisms involved in retrovirus-induced neurodegeneration and may also have analogies to other types of neurodegeneration.
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Affiliation(s)
- Karin E Peterson
- Department of Pathobiological Sciences, School of Veterinary Medicine, Skip Bertman Dr., Louisiana State University, Baton Rouge, LA 70803, USA.
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Holguin A, O'Connor KA, Biedenkapp J, Campisi J, Wieseler-Frank J, Milligan ED, Hansen MK, Spataro L, Maksimova E, Bravmann C, Martin D, Fleshner M, Maier SF, Watkins LR. HIV-1 gp120 stimulates proinflammatory cytokine-mediated pain facilitation via activation of nitric oxide synthase-I (nNOS). Pain 2004; 110:517-530. [PMID: 15288392 DOI: 10.1016/j.pain.2004.02.018] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2003] [Revised: 12/31/2003] [Accepted: 02/17/2004] [Indexed: 10/26/2022]
Abstract
It has become clear that spinal cord glia (microglia and astrocytes) importantly contribute to the creation of exaggerated pain responses. One model used to study this is peri-spinal (intrathecal, i.t.) administration of gp120, an envelope protein of HIV-1 known to activate glia. Previous studies demonstrated that i.t. gp120 produces pain facilitation via the release of glial proinflammatory cytokines. The present series of studies tested whether spinal nitric oxide (NO) contributes to i.t. gp120-induced mechanical allodynia and, if so, what effect NO has on spinal proinflammatory cytokines. gp120 stimulation of acutely isolated lumbar dorsal spinal cords released NO as well as proinflammatory cytokines (tumor necrosis factor-alpha, interleukin-1beta (IL1), interleukin-6 (IL6)), thus identifying NO as a candidate mediator of gp120-induced behavioral effects. Behaviorally, identical effects were observed when gp120-induced mechanical allodynia was challenged by i.t. pre-treatment with either a broad-spectrum nitric oxide synthase (NOS) inhibitor (L-NAME) or 7-NINA, a selective inhibitor of NOS type-I (nNOS). Both abolished gp120-induced mechanical allodynia. While the literature pre-dominantly documents that proinflammatory cytokines stimulate the production of NO rather than the reverse, here we show that gp120-induced NO increases proinflammatory cytokine mRNA levels (RT-PCR) and both protein expression and protein release (serial ELISA). Furthermore, gp120 increases mRNA for IL1 converting enzyme and matrix metalloproteinase-9, enzymes responsible for activation and release of proinflammatory cytokines.
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Affiliation(s)
- Adelina Holguin
- Department of Psychology and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309, USA Department of Kinesiology and Applied Physiology, and the Center for Neuroscience, University of Colorado at Boulder, Boulder, CO 80309, USA Department of Pharmacology, Amgen, Thousand Oaks, CA 91320, USA
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Navarra M, Baltrons MA, Sardón T, Pedraza CE, García A. HIV-1 coat protein gp120 decreases NO-dependent cyclic GMP accumulation in rat brain astroglia by increasing cyclic GMP phosphodiesterase activity. Neurochem Int 2004; 45:937-46. [PMID: 15312988 DOI: 10.1016/j.neuint.2004.03.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The human immunodeficiency virus type-1 (HIV-1) coat glycoprotein gp120 has been proposed as a likely etiologic agent of HIV-associated dementia (HAD). The pathogenic mechanisms underlying HAD have not yet been fully elucidated, but different evidences indicate that glial cells play an essential role in the development and amplification of the disease. The NO/cyclic GMP (cGMP) system is a widespread signal transduction pathway in the CNS involved in numerous physiological and pathological functions. Increased expression of NO synthase has been reported in the brain of AIDS patients and in cultured rodent glial cells exposed to gp120. The aim of this study was to investigate if gp120 could cause alterations in the metabolism of the NO physiological messenger cGMP that could contribute to the pathogenesis of HAD. Here, we show that long-term treatment (more than 24 h) of rat cerebellar astrocyte-enriched cultures with gp120 (10 nM) induces changes in the cultured cells--astrocyte stellation and proliferation of ameboid microglia--compatible with the acquisition of a reactive phenotype and reduces the capacity of the astrocytes to accumulate cGMP in response to NO in a time-dependent manner (maximal after 72 h). Measurements in cell extracts show that gp120 enhances Ca2+-independent cGMP phosphodiesterase activity by 80-100% without significantly affecting soluble guanylyl cyclase (sGC). Experiments in whole cells using specific phosphodiesterase inhibitors indicate that the viral protein increases the activity of cGMP specific phosphodiesterase 5.
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Affiliation(s)
- Michele Navarra
- Instituto de Biotecnología y Biomedicina V. Villar Palasí and Departamento de Bioquímica y Biología Molecular, Universidad Autónoma de Barcelona, 08193 Bellaterra, Spain
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37
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Kim SY, Choi EC, Woo Jo Y, Henson JW, Kim HS. Transcriptional activation of JC virus early promoter by phorbol ester and interleukin-1β: critical role of nuclear factor-1. Virology 2004; 327:60-9. [PMID: 15327898 DOI: 10.1016/j.virol.2004.06.021] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Revised: 04/19/2004] [Accepted: 06/11/2004] [Indexed: 10/26/2022]
Abstract
JC virus causes the fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML) under immunosuppressive states such as AIDS. During the pathogenesis of AIDS, HIV-infected microglia secrete cytokines including interleukin-1 and tumor necrosis factor-alpha (TNF-alpha), which affect neuronal cells resulting in dysfunction of the CNS. We hypothesized that extracellular stimuli released from HIV-infected microglia may reactivate JC virus by affecting neighboring oligodendrocytes. In the present study, we found that phorbol myristate acetate (PMA) and interleukin-1beta (IL-1beta) dramatically increased JC virus transcription in glial cells. Site-directed mutagenesis and gel shift analyses revealed that PMA and IL-1beta strongly induced nuclear factor-1 (NF-1) binding to the JC virus enhancer region, increasing transcriptional activity of the viral early promoter. Additionally, we demonstrated that protein kinase C (PKC) pathways were involved in the PMA/IL-1beta-mediated up-regulation of the JC virus early promoter. These findings may represent one of the possible mechanisms for higher incidence of PML among AIDS patients.
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Affiliation(s)
- So-Young Kim
- Department of Neuroscience, Ewha Institute of Neuroscience and Medical Research Center, Ewha Womans University School of Medicine, Seoul, South Korea
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38
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Minghetti L, Visentin S, Patrizio M, Franchini L, Ajmone-Cat MA, Levi G. Multiple actions of the human immunodeficiency virus type-1 Tat protein on microglial cell functions. Neurochem Res 2004; 29:965-78. [PMID: 15139295 DOI: 10.1023/b:nere.0000021241.90133.89] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The human immunodeficiency virus type-1 (HIV-1) regulatory protein Tat is produced in the early phase of infection and is essential for virus replication. Together with other viral products, Tat has been implicated in the pathogenesis of HIV-1-associated dementia (HAD). As HIV-1 infection in the brain is very limited and macrophage/microglial cells are the only cellular type productively infected by the virus, it has been proposed that many of the viral neurotoxic effects are mediated by microglial products. We and others have shown that Tat affects the functional state of microglial cells, supporting the hypothesis that activated microglia play a role in the neuropathology associated with HIV-1 infection. This review describes the experimental evidence indicating that Tat stimulates microglia to synthesize potentially neurotoxic molecules, including proinflammatory cytokines and free radicals, and interferes with molecular mechanisms controlling cAMP levels, intracellular [Ca2+], and ion channel expression.
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Affiliation(s)
- Luisa Minghetti
- Department of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
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39
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Abstract
Human immunodeficiency virus type I (HIV-1) infection leads to penetration of the central nervous system (CNS) in virtually all infected individuals and HIV-1-induced encephalopathy in a significant number of untreated patients. The molecular mechanisms by which HIV-1 enters the CNS and yields CNS dysfunction are still unclear. Our laboratories and others have begun to explore the direct effects of prioritized HIV-1-specific proteins on diverse human CNS cell types. One of these proteins, the accessory HIV-1 protein Vpr, is a critical moiety in these studies, and will be discussed in this article.
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Affiliation(s)
- Roger J Pomerantz
- Biochemistry and Molecular Pharmacology, Division of Infectious Disease and Environmental Medicine, Center for Human Virology and Biodefense, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
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40
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Milligan ED, Maier SF, Watkins LR. Review: neuronal-glial interactions in central sensitization. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/s1537-5897(03)00044-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Zhang K, Rana F, Silva C, Ethier J, Wehrly K, Chesebro B, Power C. Human immunodeficiency virus type 1 envelope-mediated neuronal death: uncoupling of viral replication and neurotoxicity. J Virol 2003; 77:6899-912. [PMID: 12768009 PMCID: PMC156161 DOI: 10.1128/jvi.77.12.6899-6912.2003] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Although brain tissue from patients with human immunodeficiency virus (HIV) and/or AIDS is consistently infected by HIV type 1 (HIV-1), only 20 to 30% of patients exhibit clinical or neuropathological evidence of brain injury. Extensive HIV-1 sequence diversity is present in the brain, which may account in part for the variability in the occurrence of HIV-induced brain disease. Neurological injury caused by HIV-1 is mediated directly by neurotoxic viral proteins or indirectly through excess production of host molecules by infected or activated glial cells. To elucidate the relationship between HIV-1 infection and neuronal death, we examined the neurotoxic effects of supernatants from human 293T cells or macrophages expressing recombinant HIV-1 virions or gp120 proteins containing the V1V3 or C2V3 envelope region from non-clade B, brain-derived HIV-1 sequences. Neurotoxicity was measured separately as apoptosis or total neuronal death, with apoptosis representing 30 to 80% of the total neuron death observed, depending on the individual virus. In addition, neurotoxicity was dependent on expression of HIV-1 gp120 and could be blocked by anti-gp120 antibodies, as well as by antibodies to the human CCR5 and CXCR4 chemokine receptors. Despite extensive sequence diversity in the recombinant envelope region (V1V3 or C2V3), there was limited variation in the neurotoxicity induced by supernatants from transfected 293T cells. Conversely, supernatants from infected macrophages caused a broader range of neurotoxicity levels that depended on each virus and was independent of the replicative ability of the virus. These findings underscore the importance of HIV-1 envelope protein expression in neurotoxic pathways associated with HIV-induced brain disease and highlight the envelope as a target for neuroprotective therapeutic interventions.
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Affiliation(s)
- Kunyan Zhang
- Department of Clinical Neurosciences, University of Calgary, Alberta, Canada
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42
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Okamoto M, Wang X, Debyser Z, De Clercq E, Baba M. Establishment of an in vitro assay system mimicking human immunodeficiency virus type 1-induced neural cell death and evaluation of inhibitors thereof. J Virol Methods 2003; 108:195-203. [PMID: 12609687 DOI: 10.1016/s0166-0934(02)00288-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Human immunodeficiency virus type 1 (HIV-1)-associated central nervous system disorders, including encephalopathy, often occur in the late stage of HIV-1 infection. Some inflammatory cytokines and HIV-1 antigens released from infected microglia or brain macrophages are considered to play an important role in neuropathogenesis. In this study, an in vitro assay system has been established for the evaluation of neural cell death, which would be predictive of the pathogenesis of neural cell death in vivo. The human neuroblastoma cell line SK-N-SH was differentiated to a neural phenotype with retinoic acid, while the promyelocytic cell line HL-60 and its HIV-1-infected clone OM-10.1 were differentiated to macrophages with phorbol myristate acetate. When neural (differentiated SK-N-SH) cells were cocultured with either uninfected or HIV-1-infected macrophages (differentiated HL-60 or OM-10.1 cells, respectively) for 3-5 days, significant neural cell death was observed in the cells cocultured with infected macrophages. Direct contact with macrophages was not necessary for the induction of neural cell death, since indirect coculture or coculture supernatants could also induce neural cell death. Large amounts of cytokines and chemokines were released in the coculture supernatants. The CXCR4 antagonist AMD3100 and the HIV-1 transcription inhibitor K-37 partially inhibited neural cell death. These results indicate that this system seems to be a useful tool for the evaluation of compounds against HIV-1-induced neural cell death.
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Affiliation(s)
- Mika Okamoto
- Faculty of Medicine, Division of Human Retroviruses, Center for Chronic Viral Diseases, Faculty of Medicine Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima 890-8520, Japan
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Farr SA, Banks WA, Uezu K, Freed EO, Kumar VB, Morley JE. Mechanisms of HIV type 1-induced cognitive impairment: evidence for hippocampal cholinergic involvement with overstimulation of the VIPergic system by the viral coat protein core. AIDS Res Hum Retroviruses 2002; 18:1189-95. [PMID: 12487825 DOI: 10.1089/08892220260387931] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
HIV-1 is associated with a neuroAIDS syndrome that includes cognitive impairment. Several components of HIV-1 are capable of affecting cognition, but which of these is the major mediator is unknown. We injected into the lateral cerebral ventricle of mice HIV-1 pseudoviruses expressing the full viral genome with or without the viral coat glycoproteins, gp120/gp41. Only virus possessing gp120/gp41 induced defects in memory as assessed in an active avoidance T-maze footshock paradigm. By itself, gp120 also induced impairments that were reversed by hippocampal cholinergic stimulation. Paradoxically, low doses of gp120 could improve memory. Such low-dose, paradoxic improvement is a characteristic of substances that impair memory by overstimulating pathways that normally sustain memory. Consistent with this, a low, but not a high, dose of gp120 reversed memory impairment induced by overstimulation of the VIPergic system, a memory-sustaining pathway. Further characterization showed that two strains of gp120 (SF and MN) were equally effective at improving memory and that, unlike other actions of gp120, glycation was not required. We conclude that (1) the predominant cognitive-impairing component of HIV-1 is its viral coat glycoproteins, (2) gp120 impairs memory by overstimulating pathways that normally sustain memory, (3) the cognitive effect of gp120 is mediated by its protein core, and (4) gp120 likely impairs memory by affecting the cholinergic/VIPergic system.
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Affiliation(s)
- Susan A Farr
- Geriatric Research Education and Clinical Center (GRECC), VA Medical Center, St. Louis, Missouri 63106, USA
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44
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Liu X, Jana M, Dasgupta S, Koka S, He J, Wood C, Pahan K. Human immunodeficiency virus type 1 (HIV-1) tat induces nitric-oxide synthase in human astroglia. J Biol Chem 2002; 277:39312-9. [PMID: 12167619 PMCID: PMC2041896 DOI: 10.1074/jbc.m205107200] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) infection is known to cause neuronal injury and dementia in a significant proportion of patients. However, the mechanism by which HIV-1 mediates its deleterious effects in the brain is poorly defined. The present study was undertaken to investigate the effect of the HIV-1 tat gene on the expression of inducible nitric-oxide synthase (iNOS) in human U373MG astroglial cells and primary astroglia. Expression of the tat gene as RSV-tat but not that of the CAT gene as RSV-CAT in U373MG astroglial cells led to the induction of NO production and the expression of iNOS protein and mRNA. Induction of NO production by recombinant HIV-1 Tat protein and inhibition of RSV-tat-induced NO production by anti-Tat antibodies suggest that RSV-tat-induced production of NO is dependent on Tat and that Tat is secreted from RSV-tat-transfected astroglia. Similar to U373MG astroglial cells, RSV-tat also induced the production of NO in human primary astroglia. The induction of human iNOS promoter-derived luciferase activity by the expression of RSV-tat suggests that RSV-tat induces the transcription of iNOS. To understand the mechanism of induction of iNOS, we investigated the role of NF-kappaB and C/EBPbeta, transcription factors responsible for the induction of iNOS. Activation of NF-kappaB as well as C/EBPbeta by RSV-tat, stimulation of RSV-tat-induced production of NO by the wild type of p65 and C/EBPbeta, and inhibition of RSV-tat-induced production of NO by deltap65, a dominant-negative mutant of p65, and deltaC/EBPbeta, a dominant-negative mutant of C/EBPbeta, suggest that RSV-tat induces iNOS through the activation of NF-kappaB and C/EBPbeta. In addition, we show that extracellular signal-regulated kinase (ERK) but not that p38 mitogen-activated protein kinase (MAPK) is involved in RSV-tat induced production of NO. Interestingly, PD98059, an inhibitor of the ERK pathway, and deltaERK2, a dominant-negative mutant of ERK2, inhibited RSV-tat-induced production of NO through the inhibition of C/EBPbeta but not that of NF-kappaB. This study illustrates a novel role for HIV-1 tat in inducing the expression of iNOS in human astrocytes that may participate in the pathogenesis of HIV-associated dementia.
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Affiliation(s)
- Xiaojuan Liu
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, Nebraska 68583
| | - Malabendu Jana
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, Nebraska 68583
| | - Subhajit Dasgupta
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, Nebraska 68583
| | - Sreenivas Koka
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, Nebraska 68583
| | - Jun He
- Nebraska Center for Virology and School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588
| | - Charles Wood
- Nebraska Center for Virology and School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588
| | - Kalipada Pahan
- To whom correspondence should be addressed: Dept. of Oral Biology, University of Nebraska Medical Center, 40th and Holdrege, Lincoln, NE 68583-0740. Tel.: 402-472 -1324; Fax: 402-472-2551; E-mail:
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45
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Haughey NJ, Mattson MP. Calcium dysregulation and neuronal apoptosis by the HIV-1 proteins Tat and gp120. J Acquir Immune Defic Syndr 2002; 31 Suppl 2:S55-61. [PMID: 12394783 DOI: 10.1097/00126334-200210012-00005] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Patients with AIDS often develop cognitive and motor dysfunction that results from damage to synapses and death of neurons in brain regions such as the hippocampus and basal ganglia. This brain syndrome, called AIDS dementia or HIV encephalitis, is believed to result from the infection of one or more populations of mitotic brain cells with HIV-1, which then release viral proteins that are toxic to neurons. Two neurotoxic HIV-1 proteins have been identified, the viral coat protein gp120 and the transcription regulator Tat. Each of these proteins can induce apoptosis of cultured neurons and can render neurons vulnerable to excitotoxicity and oxidative stress. Gp120 and Tat also cause neuronal dysfunction and death in rodents in vivo. Both gp120 and Tat disrupt neuronal calcium homeostasis by perturbing calcium-regulating systems in the plasma membrane and endoplasmic reticulum. Accordingly, drugs that stabilize cellular calcium homeostasis can protect neurons against the toxic effects of gp120 and Tat. By altering voltage-dependent calcium channels, glutamate receptor channels, and membrane transporters, the HIV-1 proteins promote calcium overload, oxyradical production, and mitochondrial dysfunction. A better understanding of how gp120 and Tat disrupt neuronal calcium homeostasis may lead to the development of novel treatments for AIDS patients.
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Affiliation(s)
- Norman J Haughey
- Laboratory of Neurosciences, National Institute on Aging Gerontology Research Center, Baltimore, Maryland 21224, USA
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Tzeng SF, Lee JL, Kuo JS, Yang CS, Murugan P, Ai Tai L, Chu Hwang K. Effects of malonate C60 derivatives on activated microglia. Brain Res 2002; 940:61-8. [PMID: 12020876 DOI: 10.1016/s0006-8993(02)02592-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Activated microglia in acute and chronic neurodegenerative disease of the central nervous system (CNS) can produce large amounts of free radicals, such as reactive oxygen species (ROS), which subsequently contribute to neuropathogenesis. Thus, it is believed that the induction of microglial deactivation can reduce neuronal injury. Buckminsterfullerene (C60) derivatives that possess free radical scavenging properties have been demonstrated to prevent neuronal cell death caused by excitotoxic insult. In this study, we investigated the biological role of two malonic acid C60 derivatives referred as trans-2 and trans-3 on microglia in the presence of the endotoxin lipopolysaccharide (LPS). Treatment of LPS-activated microglia with trans-2 and trans-3 induced a significant degree of transformation of amoeboid microglia to the ramified phenotype. To understand the mechanism underlying this C60 mediated microglial morphological transformation, we examined the production of proinflammatory cytokines, interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), as well as the final NO products (nitrate and nitrite) in the microglial culture supernatant. Although inducible nitric oxide (iNOS) mRNA and protein expression in LPS-activated microglia were slightly decreased by trans-2 and trans-3, levels of nitrate and nitrite were unaffected. Paradoxically, trans-2 and trans-3 were found to increase the release of IL-1beta in the activated microglial culture. However, trans-2 and trans-3 improved the activity of the antioxidant enzyme, superoxide dismutase (SOD) in LPS-treated microglia. Therefore, our results suggest that the C60 derivatives might increase microglial SOD enzymatic activity which causes microglial morphological transformation from the activated amoeboid phenotype to the resting ramified form.
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Affiliation(s)
- Shun-Fen Tzeng
- Department of Biology, National Cheng Kung University, Tainan City, Taiwan.
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47
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Johnston JB, Silva C, Power C. Envelope gene-mediated neurovirulence in feline immunodeficiency virus infection: induction of matrix metalloproteinases and neuronal injury. J Virol 2002; 76:2622-33. [PMID: 11861828 PMCID: PMC135953 DOI: 10.1128/jvi.76.6.2622-2633.2002] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2001] [Accepted: 12/05/2001] [Indexed: 12/18/2022] Open
Abstract
The release of neurotoxins by activated brain macrophages or microglia is one mechanism proposed to contribute to the development of neurological disease following infection by lentiviruses, including feline immunodeficiency virus (FIV). Since molecular diversity in the lentiviral envelope gene influences the expression of host molecules implicated in neuronal injury, the role of the envelope sequence in FIV neuropathogenesis was investigated by using the neurovirulent FIV strain V1CSF, the nonneurovirulent strain Petaluma, and a chimera (FIVCh) containing the V1CSF envelope gene in a Petaluma background. All three viruses replicated in primary feline macrophages with equal efficiency, but conditioned medium from V1CSF- or FIVCh-infected cells was significantly more neurotoxic than medium from Petaluma-infected cultures (P < 0.001) and could be attenuated in a dose-dependent manner by treatment with either the matrix metalloproteinase (MMP) inhibitor prinomastat (PMT) or function-blocking antibodies to MMP-2. Although FIV sequences were detectable by PCR in brain tissue from neonatal cats infected with each of the viral strains, immunohistochemistry revealed increased astrogliosis and macrophage activation in the brains of V1CSF- and FIVCh-infected cats relative to the other groups, together with elevated markers of neuronal stress that included morphological changes and increased c-fos immunoreactivity. Similarly, MMP-2, but not MMP-9, mRNA and protein expression was increased in brain tissues of V1CSF- and FIVCh-infected cats relative to Petaluma-infected animals (P < 0.01). Infection with V1CSF or FIVCh was also associated with greater CD4(+) cell depletion (P < 0.001) and neurodevelopmental delays (P < 0.005), than in Petaluma-infected animals; these deficits improved following PMT therapy. These findings indicated that diversity in the envelope gene sequence influenced the neurovirulence exhibited by FIV both in vitro and in vivo, possibly through a mechanism involving the differential induction of MMP-2.
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Affiliation(s)
- J B Johnston
- Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada
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48
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Hansen R, Sauder C, Czub S, Bachmann E, Schimmer S, Hegyi A, Czub M. Activation of microglia cells is dispensable for the induction of rat retroviral spongiform encephalopathy. J Neurovirol 2001; 7:501-10. [PMID: 11704882 DOI: 10.1080/135502801753248088] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In the course of retroviral CNS infections, microglia activation has been observed frequently, and it has been hypothesized that activated microglia produce and secrete neurotoxic products like proinflammatory cytokines, by this promoting brain damage. We challenged this hypothesis in a rat model for neurodegeneration. In a kinetic study, we found that microglia cells of rats neonatally inoculated with neurovirulent murine leukemia virus (MuLV) NT40 became infected in vivo to maximal levels within 9-13 days postinoculation (d.p.i.). Beginning from 13 d.p.i., degenerative alterations, i.e., vacuolization of neurons and neuropil were found in cerebellar and other brain-stem nuclei. Elevated numbers of activated microglia cells--as revealed by immunohistochemical staining with monoclonal antibody ED1--were first detected at 19 d.p.i. and were always locally associated with degenerated areas but not with nonaltered, yet infected, brain regions. Both neuropathological changes and activated microglia cells increased in intensity and numbers, respectively, with ongoing infection but did not spread to other than initially affected brain regions. By ribonuclease protection assays, we were unable to detect differences in the expression levels of tumor-necrosis-factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interleukin-6 (IL-6) in microglia cells nor in total brains from infected versus uninfected rats. Our results suggest that the activation of microglia in the course of MuLV neurodegeneration is rather a reaction to, and not the cause of, neuronal damage. Furthermore, overt expression of the proinflammatory cytokines TNF-alpha, IL-1beta, and IL-6 within the CNS is not required for the induction of retroviral associated neurodegeneration in rats.
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Affiliation(s)
- R Hansen
- Institut für Virologie und Immunbiologie, Universität Würzburg, Germany
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49
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Belmadani A, Zou JY, Schipma MJ, Neafsey EJ, Collins MA. Ethanol pre-exposure suppresses HIV-1 glycoprotein 120-induced neuronal degeneration by abrogating endogenous glutamate/Ca2+-mediated neurotoxicity. Neuroscience 2001; 104:769-81. [PMID: 11440808 DOI: 10.1016/s0306-4522(01)00139-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The neurotoxic mechanism of HIV-1 envelope glycoprotein 120 (gp120) involves glutamatergic (NMDA) receptor/Ca2+-dependent excitotoxicity, mediated in part via glia. Pro-inflammatory cytokines also may have roles. We have reported that pre-exposure of brain cultures to 'physiological' ethanol concentrations (20-30 mM) protects against neuronal damage from HIV-1 gp120, but not from the direct receptor agonist, NMDA. Using lactate dehydrogenase assays and propidium iodide staining of rat organotypic hippocampal-entorhinal cortical slice cultures we determined that ethanol's suppression of gp120 neurotoxicity required at least 4 days of pretreatment. The gp120-induced neurotoxicity was accompanied by interleukin-6 elevations that were not affected by the pretreatment. However, gp120 induced substantial, early increases in extracellular glutamate levels that were blocked by ethanol pretreatment, conceivably abrogating excitotoxicity. Consistent with abrogation of excitotoxic pathways, fura-2 imaging showed selective deficits in gp120-dependent intracellular Ca2+ responses in ethanol-pretreated slices. Gp120 is believed to increase glutamate levels by both stimulating release and inhibiting (re)uptake. Results with a labeled glutamate analog, D-[3H]aspartate, revealed that gp120's inhibition of glutamate uptake, rather than its stimulation of release, was abolished after ethanol. Further studies indicated that two converging effects of ethanol pretreatment may underlie the abolishment of gp120-mediated glutamate uptake inhibition: (a) blockade of gp120-induced release (ostensibly from glia) of arachidonic acid, an inhibitor of astroglial glutamate reuptake, and (b) modest proliferation and activation of astroglia upon gp120 stimulation--which are likely to augment glutamate transporters. Thus, as with gp120 itself, glia and glutamate/arachidonic acid regulation appear to be important targets for ethanol. Since moderate ethanol consumption is as common among HIV-infected individuals as in the general population, this newly recognized neuroprotective (and apparently anti-excitotoxic) effect of ethanol withdrawal in vitro could be important, but it requires further study before its significance, if any, is understood.
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Affiliation(s)
- A Belmadani
- Department of Cell Biology, Neurobiology and Anatomy, Loyola University Stritch School of Medicine, Maywood, IL 60153, USA
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50
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Langford D, Masliah E. Crosstalk between components of the blood brain barrier and cells of the CNS in microglial activation in AIDS. Brain Pathol 2001; 11:306-12. [PMID: 11414473 PMCID: PMC8098377 DOI: 10.1111/j.1750-3639.2001.tb00401.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
During the progression of AIDS, a majority of patients develop cognitive disorders such as HIV encephalitis (HIVE) and AIDS dementia complex (ADC), which correlate closely with macrophage infiltration into the brain and microglial activation. Microglial activation occurs in response to infection, inflammation and neurological disorders including HIVE, Alzheimer's disease, Parkinson's disease and multiple sclerosis. Microglia can be activated by immunoreactive cells independent of, but enhanced by HIV infection, from at least two routes. Activation may occur from signals originating from activated monocytes and lymphocytes in the blood stream, which initiate a cascade of stimuli that ultimately reach microglia in the brain or from activated macrophages/microglia/astrocytes within the brain. Effects of microglial activation stemming from both systemic and CNS HIV infection act together to commence signaling feedback, leading to HIVE and increased neurodegeneration. Most recent data indicate that in AIDS patients, microglial activation in the brain with subsequent release of excitotoxins, cytokines and chemokines leads to neurodegeneration and cognitive impairment. Since the presence of HIV in the brain results from migration of infected monocytes and lymphocytes across the vascular boundary, the development of novel therapies aimed at protecting the integrity of the blood brain barrier (BBB) upon systemic HIV infection is critical for controlling CNS infection.
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Affiliation(s)
- D Langford
- Department of Neurosciences, University of California San Diego, La Jolla 92093, USA
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