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Zhu Y, Wang R, Pappas AC, Seifert P, Savol A, Sadreyev RI, Sun D, Jakobs TC. Astrocytes in the Optic Nerve Are Heterogeneous in Their Reactivity to Glaucomatous Injury. Cells 2023; 12:2131. [PMID: 37681863 PMCID: PMC10486930 DOI: 10.3390/cells12172131] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 07/14/2023] [Accepted: 08/18/2023] [Indexed: 09/09/2023] Open
Abstract
The optic nerve head is thought to be the site of initial injury to retinal ganglion cell injury in glaucoma. In the initial segment of the optic nerve directly behind the globe, the ganglion cell axons are unmyelinated and come into direct contact to astrocytes, suggesting that astrocytes may play a role in the pathology of glaucoma. As in other parts of the CNS, optic nerve head astrocytes respond to injury by characteristic changes in cell morphology and gene expression profile. Using RNA-sequencing of glaucomatous optic nerve heads, single-cell PCR, and an in-vivo assay, we demonstrate that an up-regulation of astrocytic phagocytosis is an early event after the onset of increased intraocular pressure. We also show that astrocytes in the glial lamina of the optic nerve are apparently functionally heterogeneous. At any time, even in naïve nerves, some of the cells show signs of reactivity-process hypertrophy, high phagocytic activity, and expression of genetic markers of reactivity whereas neighboring cells apparently are inactive. A period of increased intraocular pressure moves more astrocytes towards the reactive phenotype; however, some cells remain unreactive even in glaucomatous nerves.
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Affiliation(s)
- Ying Zhu
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
- Department of Ophthalmology, Stanford University, 1651 Page Mill Road, Palo Alto, CA 94304, USA
| | - Rui Wang
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
- Department of Ophthalmology, The First Affiliated Hospital of Northwest University, Xi’an 710002, China
| | - Anthony C. Pappas
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
| | - Philip Seifert
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
| | - Andrej Savol
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Pathology, Massachusetts General Hospital and Harvard Medical School, 185 Cambridge St., Boston, MA 02114, USA
| | - Ruslan I. Sadreyev
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
- Department of Pathology, Massachusetts General Hospital and Harvard Medical School, 185 Cambridge St., Boston, MA 02114, USA
| | - Daniel Sun
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
| | - Tatjana C. Jakobs
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary/Schepens Eye Research Institute, Harvard Medical School, 20 Staniford Street, Boston, MA 02114, USA
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Yang SS, Simtchouk S, Gibon J, Klegeris A. Regulation of the phagocytic activity of astrocytes by neuroimmune mediators endogenous to the central nervous system. PLoS One 2023; 18:e0289169. [PMID: 37498903 PMCID: PMC10374099 DOI: 10.1371/journal.pone.0289169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2023] [Accepted: 07/11/2023] [Indexed: 07/29/2023] Open
Abstract
The phagocytic activity of glial cells is essential for maintaining normal brain activity, and its dysfunction may contribute to the central nervous system (CNS) pathologies, including neurodegenerative diseases. Phagocytic activity is one of the well-established neuroimmune functions of microglia. Although emerging evidence indicates that astrocytes can also function as CNS phagocytes in humans and rodents, limited information is available about the molecular mechanism regulating this function. To address this knowledge gap, we studied modulation of the phagocytic activity of human U118 MG astrocytic cells and murine primary astrocytes by four CNS inflammatory mediators and bacterial endotoxin lipopolysaccharide (LPS). LPS and cytochrome c (CytC) upregulated, while interferon (IFN)-γ downregulated, phagocytosis of latex beads by human astrocytic cells and phagocytosis of synaptosomes by murine primary astrocytes. Interleukin (IL)-1β and tumor necrosis factor (TNF)-α had no effect on the phagocytic activity of human astrocytic cells but upregulated this function in murine astrocytes. Varying effects of combinations of the above inflammatory mediators were observed in these two cell types. LPS- and CytC-induced phagocytic activity of human astrocytic cells was partially mediated by activation of toll-like receptor 4 (TLR4). By monitoring other functions of astrocytes, we concluded there were no correlations between the effects of the mediators studied on astrocyte phagocytic activity and their secretion of cytokines, cytotoxins, or glutamate. Our study identified four candidate CNS regulators of astrocyte phagocytic activity. Future investigation of molecular mechanisms behind this regulation could identify novel therapeutic targets allowing modulation of this astrocyte-mediated clearance mechanism in CNS pathologies.
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Affiliation(s)
- Sijie Shirley Yang
- Department of Biology, University of British Columbia Okanagan Campus, University Way, Kelowna, British Columbia, Canada
| | - Svetlana Simtchouk
- Department of Biology, University of British Columbia Okanagan Campus, University Way, Kelowna, British Columbia, Canada
| | - Julien Gibon
- Department of Biology, University of British Columbia Okanagan Campus, University Way, Kelowna, British Columbia, Canada
| | - Andis Klegeris
- Department of Biology, University of British Columbia Okanagan Campus, University Way, Kelowna, British Columbia, Canada
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Bowles KR, Pugh DA, Pedicone C, Oja L, Weitzman SA, Liu Y, Chen JL, Disney MD, Goate AM. Development of MAPT S305 mutation models exhibiting elevated 4R tau expression, resulting in altered neuronal and astrocytic function. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.02.543224. [PMID: 37333200 PMCID: PMC10274740 DOI: 10.1101/2023.06.02.543224] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Due to the importance of 4R tau in the pathogenicity of primary tauopathies, it has been challenging to model these diseases in iPSC-derived neurons, which express very low levels of 4R tau. To address this problem we have developed a panel of isogenic iPSC lines carrying the MAPT splice-site mutations S305S, S305I or S305N, derived from four different donors. All three mutations significantly increased the proportion of 4R tau expression in iPSC-neurons and astrocytes, with up to 80% 4R transcripts in S305N neurons from as early as 4 weeks of differentiation. Transcriptomic and functional analyses of S305 mutant neurons revealed shared disruption in glutamate signaling and synaptic maturity, but divergent effects on mitochondrial bioenergetics. In iPSC-astrocytes, S305 mutations induced lysosomal disruption and inflammation and exacerbated internalization of exogenous tau that may be a precursor to the glial pathologies observed in many tauopathies. In conclusion, we present a novel panel of human iPSC lines that express unprecedented levels of 4R tau in neurons and astrocytes. These lines recapitulate previously characterized tauopathy-relevant phenotypes, but also highlight functional differences between the wild type 4R and mutant 4R proteins. We also highlight the functional importance of MAPT expression in astrocytes. These lines will be highly beneficial to tauopathy researchers enabling a more complete understanding of the pathogenic mechanisms underlying 4R tauopathies across different cell types.
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Affiliation(s)
- KR Bowles
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
- Ronald M. Loeb Center for Alzheimer’s disease, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - DA Pugh
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
- Ronald M. Loeb Center for Alzheimer’s disease, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - C Pedicone
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
- Ronald M. Loeb Center for Alzheimer’s disease, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - L Oja
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
- Ronald M. Loeb Center for Alzheimer’s disease, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - SA Weitzman
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
- Ronald M. Loeb Center for Alzheimer’s disease, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - Y Liu
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
- Ronald M. Loeb Center for Alzheimer’s disease, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
| | - JL Chen
- Department of Chemistry, Scripps Research Institute, Jupiter, FL, United States of America
| | - MD Disney
- Department of Chemistry, Scripps Research Institute, Jupiter, FL, United States of America
| | - AM Goate
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
- Ronald M. Loeb Center for Alzheimer’s disease, Icahn School of Medicine at Mount Sinai, New York, NY, United States of America
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Extracellular Cardiolipin Modulates Select Immune Functions of Astrocytes in Toll-Like Receptor (TLR) 4-Dependent Manner. Mediators Inflamm 2022; 2022:9946439. [PMID: 35369030 PMCID: PMC8975658 DOI: 10.1155/2022/9946439] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 01/11/2022] [Accepted: 02/16/2022] [Indexed: 12/23/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by chronic neuroinflammation, which is partially mediated by dysregulated functions of glial cells. Cardiolipin (CL) is a phospholipid normally confined to the inner mitochondrial membrane; however, it has been detected in human sera, indicating that it can exist in the extracellular space where it may interact with nearby cells. Although CL has been shown to modulate several functions of microglia in a toll-like receptor (TLR) 4-dependent manner, the effects of extracellular CL on astrocytes are unknown. In addition to their homeostatic functions, astrocytes participate in neuroimmune responses of the brain and express TLR 4. Therefore, we hypothesized that extracellular CL (1) modulates the secretion of cytokines and cytotoxins by astrocytes, as well as their phagocytic activity, and (2) acts by interacting with astrocyte TLR 4. We demonstrate that CL inhibits the lipopolysaccharide- (LPS-) induced secretion of cytotoxins and expression of glial fibrillary acidic protein (GFAP) by human U118 MG astrocytic cells. CL alone upregulates the phagocytic activity of human astrocytic cells and primary murine astrocytes. CL in combination with LPS upregulates secretion of interleukin (IL)-1β by astrocytic cells. Furthermore, CL alone increases the secretion of monocyte chemoattractant protein (MCP)-1 by astrocytic cells, which is blocked by the TLR 4-specific antagonist TAK-242. We demonstrate that CL upregulates MCP-1 secretion in the absence of its natural carrier protein, β2-glycoprotein 1, indicating that CL may be bioactive in the brain where this protein is not present. Lastly, we show that CL downregulates the expression of astrocytic TLR 4, implying that CL engages this receptor, as its activation has been shown to lead to its degradation. Overall, our study extends the list of cell type functions of which CL modulates and provides evidence that CL, or liposomes containing this phospholipid can be used to modulate specific neuroimmune functions of astrocytes.
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Kloske CM, Wilcock DM. The Important Interface Between Apolipoprotein E and Neuroinflammation in Alzheimer's Disease. Front Immunol 2020; 11:754. [PMID: 32425941 PMCID: PMC7203730 DOI: 10.3389/fimmu.2020.00754] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2020] [Accepted: 04/02/2020] [Indexed: 12/13/2022] Open
Abstract
Alzheimer’s disease (AD) is the most prevalent form of neurodegenerative disease, currently affecting over 5 million Americans with projections expected to rise as the population ages. The hallmark pathologies of AD are Aβ plaques composed of aggregated beta-amyloid (Aβ), and tau tangles composed of hyperphosphorylated, aggregated tau. These pathologies are typically accompanied by an increase in neuroinflammation as an attempt to ameliorate the pathology. This idea has pushed the field toward focusing on mechanisms and the influence neuroinflammation has on disease progression. The vast majority of AD cases are sporadic and therefore, researchers investigate genetic risk factors that could lead to AD. Apolipoprotein E (ApoE) is the largest genetic risk factor for developing AD. ApoE has 3 isoforms-ApoE2, ApoE3, and ApoE4. ApoE4 constitutes an increased risk of AD, with one copy increasing the risk about 4-fold and two copies increasing the risk about 15-fold compared to those with the ApoE3 allele. ApoE4 has been shown to play a role in Aβ deposition, tau tangle formation, neuroinflammation and many subsequent pathways. However, while we know that ApoE4 plays a role in these pathways and virtually all aspects of AD, the exact mechanism of how ApoE4 impacts AD progression is murky at best and therefore the role ApoE4 plays in these pathways needs to be elucidated. This review aims to discuss the current literature regarding the pathways and mechanisms of ApoE4 in AD progression with a focus on its role in neuroinflammation.
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Affiliation(s)
- Courtney M Kloske
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
| | - Donna M Wilcock
- Department of Physiology, Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, United States
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6
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Crespo-Castrillo A, Garcia-Segura LM, Arevalo MA. The synthetic steroid tibolone exerts sex-specific regulation of astrocyte phagocytosis under basal conditions and after an inflammatory challenge. J Neuroinflammation 2020; 17:37. [PMID: 31992325 PMCID: PMC6986022 DOI: 10.1186/s12974-020-1719-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Accepted: 01/19/2020] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Tibolone is a synthetic steroid used in clinical practice for the treatment of climacteric symptoms and osteoporosis. Active metabolites of tibolone, generated in target tissues, have an affinity for estrogen and androgen receptors. Astrocytes are direct targets for estrogenic compounds and previous studies have shown that tibolone protects brain cortical neurons in association with a reduction in reactive astrogliosis in a mouse model of traumatic brain injury. Since phagocytosis is a crucial component of the neuroprotective function exerted by astrocytes, in the present study, we have assessed whether tibolone regulates phagocytosis in primary astrocytes incubated with brain-derived cellular debris. METHODS Male and female astrocyte cell cultures were obtained from newborn (P0-P2) female and male Wistar rats. Astrocytic phagocytosis was first characterized using carboxylate beads, Escherichia coli particles, or brain-derived cellular debris. Then, the effect of tibolone on the phagocytosis of Cy3-conjugated cellular debris was quantified by measuring the intensity of Cy3 dye-emitted fluorescence in a given GFAP immunoreactive area. Before the phagocytosis assays, astrocytes were incubated with tibolone in the presence or absence of estrogen or androgen receptor antagonists or an inhibitor of the enzyme that synthesizes estradiol. The effect of tibolone on phagocytosis was analyzed under basal conditions and after inflammatory stimulation with lipopolysaccharide. RESULTS Tibolone stimulated phagocytosis of brain-derived cellular debris by male and female astrocytes, with the effect being more pronounced in females. The effect of tibolone in female astrocytes was blocked by a selective estrogen receptor β antagonist and by an androgen receptor antagonist. None of these antagonists affected tibolone-induced phagocytosis in male astrocytes. In addition, the inhibition of estradiol synthesis in the cultures enhanced the stimulatory effect of tibolone on phagocytosis in male astrocytes but blocked the effect of the steroid in female cells under basal conditions. However, after inflammatory stimulation, the inhibition of estradiol synthesis highly potentiated the stimulation of phagocytosis by tibolone, particularly in female astrocytes. CONCLUSIONS Tibolone exerts sex-specific regulation of phagocytosis in astrocytes of both sexes, both under basal conditions and after inflammatory stimulation.
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Affiliation(s)
| | - Luis-Miguel Garcia-Segura
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain.,Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludables (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain
| | - Maria-Angeles Arevalo
- Instituto Cajal, Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain. .,Centro de Investigación Biomédica en Red Fragilidad y Envejecimiento Saludables (CIBERFES), Instituto de Salud Carlos III, Madrid, Spain.
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Murta V, Schilrreff P, Rosciszewski G, Morilla MJ, Ramos AJ. G5G2.5 core-shell tecto-dendrimer specifically targets reactive glia in brain ischemia. J Neurochem 2018; 144:748-760. [DOI: 10.1111/jnc.14286] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 11/18/2017] [Accepted: 12/11/2017] [Indexed: 01/02/2023]
Affiliation(s)
- Veronica Murta
- Departamento de Histología, Embriología, Biología Celular y Genética; Facultad de Medicina; Universidad de Buenos Aires; Buenos Aires Argentina
- Laboratorio de Neuropatología Molecular; Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis” IBCN UBA-CONICET; Buenos Aires Argentina
| | - Priscila Schilrreff
- Programa de Nanomedicinas; Departamento de Ciencia y Tecnología; Universidad Nacional de Quilmes; Bernal Argentina
| | - Gerardo Rosciszewski
- Departamento de Histología, Embriología, Biología Celular y Genética; Facultad de Medicina; Universidad de Buenos Aires; Buenos Aires Argentina
- Laboratorio de Neuropatología Molecular; Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis” IBCN UBA-CONICET; Buenos Aires Argentina
| | - Maria Jose Morilla
- Programa de Nanomedicinas; Departamento de Ciencia y Tecnología; Universidad Nacional de Quilmes; Bernal Argentina
| | - Alberto Javier Ramos
- Departamento de Histología, Embriología, Biología Celular y Genética; Facultad de Medicina; Universidad de Buenos Aires; Buenos Aires Argentina
- Laboratorio de Neuropatología Molecular; Instituto de Biología Celular y Neurociencia “Prof. E. De Robertis” IBCN UBA-CONICET; Buenos Aires Argentina
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Daniele S, Zappelli E, Martini C. Trazodone regulates neurotrophic/growth factors, mitogen-activated protein kinases and lactate release in human primary astrocytes. J Neuroinflammation 2015; 12:225. [PMID: 26627476 PMCID: PMC4666178 DOI: 10.1186/s12974-015-0446-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 11/25/2015] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND In the central nervous system, glial cells provide metabolic and trophic support to neurons and respond to protracted stress and insults by up-regulating inflammatory processes. Reactive astrocytes and microglia are associated with the pathophysiology of neuronal injury, neurodegenerative diseases and major depression, in both animal models and human brains. Several studies have reported clear anti-inflammatory effects of anti-depressant treatment on astrocytes, especially in models of neurological disorders. Trazodone (TDZ) is a triazolopyridine derivative that is structurally unrelated to other major classes of antidepressants. Although the molecular mechanisms of TDZ in neurons have been investigated, it is unclear whether astrocytes are also a TDZ target. METHODS The effects of TDZ on human astrocytes were investigated in physiological conditions and following inflammatory insult with lipopolysaccharide (LPS) and tumour necrosis factor-α (TNF-α). Astrocytes were assessed for their responses to pro-inflammatory mediators and cytokines, and the receptors and signalling pathways involved in TDZ-mediated effects were evaluated. RESULTS TDZ had no effect on cell proliferation, but it decreased pro-inflammatory mediator release and modulated trophic and transcription factor mRNA expression. Following TDZ treatment, the AKT pathway was activated, whereas extracellular signal-regulated kinase and c-Jun NH2-terminal kinase were inhibited. Most importantly, a 72-h TDZ pre-treatment before inflammatory insult completely reversed the anti-proliferative effects induced by LPS-TNF-α. The expression or the activity of inflammatory mediators, including interleukin-6, c-Jun NH2-terminal kinase and nuclear factor κB, were also reduced. Furthermore, TDZ affected astrocyte metabolic support to neurons by counteracting the inflammation-mediated lactate decrease. Finally, TDZ protected neuronal-like cells against neurotoxicity mediated by activated astrocytes. These effects mainly involved an activation of 5-HT1A and an antagonism at 5-HT2A/C serotonin receptors. Fluoxetine, used in parallel, showed similar final effects nevertheless it activates different receptors/intracellular pathways. CONCLUSIONS Altogether, our results demonstrated that TDZ directly acts on astrocytes by regulating intracellular signalling pathways and increasing specific astrocyte-derived neurotrophic factor expression and lactate release. TDZ may contribute to neuronal support by normalizing trophic and metabolic support during neuroinflammation, which is associated with neurological diseases, including major depression.
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Affiliation(s)
- Simona Daniele
- Department of Pharmacy, University of Pisa, Via Bonanno Pisano, 6, Pisa, 56126, PI, Italy.
| | - Elisa Zappelli
- Department of Pharmacy, University of Pisa, Via Bonanno Pisano, 6, Pisa, 56126, PI, Italy.
| | - Claudia Martini
- Department of Pharmacy, University of Pisa, Via Bonanno Pisano, 6, Pisa, 56126, PI, Italy.
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Abstract
In glaucoma, regardless of its etiology, retinal ganglion cells degenerate and eventually die. Although age and elevated intraocular pressure (IOP) are the main risk factors, there are still many mysteries in the pathogenesis of glaucoma. The advent of genome-wide microarray expression screening together with the availability of animal models of the disease has allowed analysis of differential gene expression in all parts of the eye in glaucoma. This review will outline the findings of recent genome-wide expression studies and discuss their commonalities and differences. A common finding was the differential regulation of genes involved in inflammation and immunity, including the complement system and the cytokines transforming growth factor β (TGFβ) and tumor necrosis factor α (TNFα). Other genes of interest have roles in the extracellular matrix, cell-matrix interactions and adhesion, the cell cycle, and the endothelin system.
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Affiliation(s)
- Tatjana C Jakobs
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts 02114
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Tosi G, Vilella A, Chhabra R, Schmeisser MJ, Boeckers TM, Ruozi B, Vandelli MA, Forni F, Zoli M, Grabrucker AM. Insight on the fate of CNS-targeted nanoparticles. Part II: Intercellular neuronal cell-to-cell transport. J Control Release 2014; 177:96-107. [DOI: 10.1016/j.jconrel.2014.01.004] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 12/23/2013] [Accepted: 01/02/2014] [Indexed: 01/01/2023]
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Hernandes MS, Britto LRG. Inflammatory responses in the rat superior colliculus after eye enucleation. Brain Res Bull 2013; 101:1-6. [PMID: 24333190 DOI: 10.1016/j.brainresbull.2013.12.001] [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: 09/19/2013] [Revised: 11/26/2013] [Accepted: 12/02/2013] [Indexed: 11/17/2022]
Abstract
Ocular enucleation induces profound morphological alterations in central visual areas. However, little is known about the response of glial cells and possible inflammatory processes in visual brain areas resulting from eye enucleation. In this study, immunoblotting and immunostaining assays revealed increased expression of astrocyte and microglia markers in the rat superior colliculus (SC) between 1 and 15 days after contralateral enucleation. A transient increase of neuronal COX-2 protein expression was also found in the SC. To evaluate the role of an anti-inflammatory drug in attenuating both COX-2 and glial cell activation, the synthetic glucocorticoid dexamethasone (DEX) was administered (1 mg/kg i.p., for 3 days) to enucleated rats. Immunoblotting data revealed that DEX treatment significantly inhibited COX-2 protein expression. Postlesion immunostaining for astrocyte and microglia markers was also significantly reduced by DEX treatment. These findings suggest that the removal of retinal ganglion cell input generates inflammatory responses in central retinorecipient structures.
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Affiliation(s)
- Marina S Hernandes
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, USP, SP, Brazil.
| | - Luiz R G Britto
- Department of Physiology and Biophysics, Institute of Biomedical Sciences, USP, SP, Brazil
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Qu J, Jakobs TC. The Time Course of Gene Expression during Reactive Gliosis in the Optic Nerve. PLoS One 2013; 8:e67094. [PMID: 23826199 PMCID: PMC3694957 DOI: 10.1371/journal.pone.0067094] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 05/15/2013] [Indexed: 01/05/2023] Open
Abstract
Reactive gliosis is a complex process that involves changes in gene expression and morphological remodeling. The mouse optic nerve, where astrocytes, microglia and oligodendrocytes interact with retinal ganglion cell axons and each other, is a particularly suitable model for studying the molecular mechanisms of reactive gliosis. We triggered gliosis at the mouse optic nerve head by retro orbital nerve crush. We followed the expression profiles of 14,000 genes from 1 day to 3 months, as the optic nerve formed a glial scar. The transcriptome showed profound changes. These were greatest shortly after injury; the numbers of differentially regulated genes then dropped, returning nearly to resting levels by 3 months. Different genes were modulated with very different time courses, and functionally distinct groups of genes responded in partially overlapping waves. These correspond roughly to two quick waves of inflammation and cell proliferation, a slow wave of tissue remodeling and debris removal, and a final stationary phase that primarily reflects permanent structural changes in the axons. Responses from astrocytes, microglia and oligodendrocytes were distinctively different, both molecularly and morphologically. Comparisons to other models of brain injury and to glaucoma indicated that the glial responses depended on both the tissue and the injury. Attempts to modulate glial function after axonal injuries should consider different mechanistic targets at different times following the insult.
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Affiliation(s)
- Juan Qu
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Tatjana C. Jakobs
- Massachusetts Eye and Ear Infirmary, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Sung YH, Shin MS, Ko IG, Kim SE, Kim CJ, Ahn HJ, Yoon HS, Lee BJ. Ulinastatin suppresses lipopolysaccharide-induced prostaglandin E2 synthesis and nitric oxide production through the downregulation of nuclear factor‑κB in BV2 mouse microglial cells. Int J Mol Med 2013; 31:1030-6. [PMID: 23546639 DOI: 10.3892/ijmm.2013.1322] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Accepted: 03/15/2013] [Indexed: 11/06/2022] Open
Abstract
Ulinastatin is an intrinsic serine-protease urinary trypsin inhibitor that can be extracted and purified from human urine. Urinary trypsin inhibitors are widely used to treat patients with acute inflammatory disorders, such as shock and pancreatitis. However, although the anti-inflammatory activities of urinary trypsin inhibitors have been investigated, the mechanisms underlying their actions are not yet fully understood. In the present study, we evaluated the effect of ulinastatin on lipopolysaccharide (LPS)-induced inflammation in relation with nuclear factor-κB (NF-κB) activation using BV2 mouse microglial cells. To accomplish this, we performed a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, reverse transcription-polymerase chain reaction (RT-PCR), western blot analysis, electrophoretic mobility gel shift assay (EMSA), prostaglandin E(2) (PGE(2)) immunoassay and nitric oxide (NO) detection. The results demonstrated that ulinastatin suppressed PGE2 synthesis and NO production by inhibiting the LPS-induced mRNA and protein expression of cyclooxygenase-2 (COX-2) and inducible NO synthase (iNOS) in BV2 mouse microglial cells. Ulinastatin suppressed the activation of NF-κB in the nucleus. These findings demonstrate that ulinastatin exerts analgesic and anti-inflammatory effects that possibly occur via the suppression of COX-2 and iNOS expression through the downregulation of NF-κB activity.
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Affiliation(s)
- Yun-Hee Sung
- Department of Physical Therapy, Kyungnam University, Changwon 631-701, Republic of Korea
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Lye-Barthel M, Sun D, Jakobs TC. Morphology of astrocytes in a glaucomatous optic nerve. Invest Ophthalmol Vis Sci 2013; 54:909-17. [PMID: 23322566 DOI: 10.1167/iovs.12-10109] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
PURPOSE To establish the morphologic changes of astrocytes in the glial lamina of glaucomatous mice. METHODS A strain of mice that expresses GFP in individual astrocytes (hGFAPpr-GFP) was crossed into the DBA/2J strain that develops glaucoma. In the resulting strain (D2.hGFAPpr-GFP) we assessed the severity of glaucoma by staining the retina for neurofilaments and counting the neurons of the retinal ganglion cell layer. We observed the morphology of astrocytes in the glial lamina of the optic nerves. RESULTS D2.hGFAPpr-GFP mice developed glaucoma in an age-dependent manner. Astrocytes in the glial lamina showed morphologic changes that correlated with the severity of glaucoma. The cells showed thickening of processes from 1.3 ± 0.28 μm in nondiseased animals to 1.71 ± 0.46 μm in eyes with moderate glaucoma and 2.1 ± 0.42 μm in those with severe glaucoma. Their spatial coverage, as determined by their convex polygon area, was reduced in eyes with severe glaucoma. The astrocytes in severely glaucomatous optic nerves also showed simplification of their processes. In 6-month-old mice with no obvious signs of degeneration in the retina, we found astrocytes with appendages growing out of primary astrocyte processes into the axon bundles. This localized hypertrophy of processes was never observed in the hGFAPpr-GFP strain. CONCLUSIONS Confirming results after optic nerve crush, astrocytes in glaucomatous optic nerves had thickened and simplified processes, and reduced spatial coverage. We also found evidence of localized sprouting of new processes in early stages of the disease, before detectable changes in ganglion cell number.
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Affiliation(s)
- Ming Lye-Barthel
- Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, USA
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15
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Bonneh-Barkay D, Bissel SJ, Kofler J, Starkey A, Wang G, Wiley CA. Astrocyte and macrophage regulation of YKL-40 expression and cellular response in neuroinflammation. Brain Pathol 2011; 22:530-46. [PMID: 22074331 DOI: 10.1111/j.1750-3639.2011.00550.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Numerous inflammatory conditions are associated with elevated YKL-40 expression by infiltrating macrophages. Thus, we were surprised to observe minimal macrophage and abundant astrocyte expression of YKL-40 in neuroinflammatory conditions. The aims of the current study were to better delineate this discrepancy, characterize the factors that regulate YKL-40 expression in macrophages and astrocytes and study whether YKL-40 expression correlates with cell morphology and/or activation state. In vitro, macrophages expressed high levels of YKL-40 that was induced by classical activation and inhibited by alternative activation. Cytokines released from macrophages induced YKL-40 transcription in astrocytes that was accompanied by morphological changes and altered astrocytic motility. Because coculturing of astrocytes and macrophages did not reverse this in vitro expression pattern, additional components of the in vivo central nervous system (CNS) milieu must be required to suppress macrophage and induce astrocyte expression of YKL-40.
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16
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Bruno CJ, Greco TM, Ischiropoulos H. Nitric oxide counteracts the hyperoxia-induced proliferation and proinflammatory responses of mouse astrocytes. Free Radic Biol Med 2011; 51:474-9. [PMID: 21605665 PMCID: PMC3118916 DOI: 10.1016/j.freeradbiomed.2011.04.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2010] [Revised: 04/20/2011] [Accepted: 04/22/2011] [Indexed: 12/21/2022]
Abstract
Preclinical studies in the premature baboon evaluating the efficacy and potential toxicity of inhaled nitric oxide indicated a significant effect on astrocyte area density, suggesting phenotypic and functional changes in astrocytes upon exposure to nitric oxide. However, the effects of nitric oxide and oxygen, the two major therapeutic gases utilized in neonatal intensive care, on astrocyte morphology and function remain vastly unknown. Herein, we report that exposure of mouse neonatal cortical astrocytes to hyperoxia results in a proinflammatory phenotype and increase in proliferation without significant changes in cellular morphology or levels of intermediate filament proteins. The proinflammatory phenotype was evident by a significant increase in cellular levels of cyclooxygenase-2 and a concomitant increase in prostaglandin E(2) secretion, a decline in the intracellular and secreted levels of apolipoprotein E, and a significant increase in the intracellular levels of clusterin. This proinflammatory phenotype was not evident upon simultaneous exposure to hyperoxia and nitric oxide. These results suggest that exposure to nitric oxide in the setting of hyperoxia confers unrecognized beneficial effects by suppressing astrocytic inflammation.
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Affiliation(s)
| | | | - Harry Ischiropoulos
- Department of Pharmacology, University of Pennsylvania Philadelphia, PA 19104
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17
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Qi J, Buzas K, Fan H, Cohen JI, Wang K, Mont E, Klinman D, Oppenheim JJ, Howard OMZ. Painful pathways induced by TLR stimulation of dorsal root ganglion neurons. THE JOURNAL OF IMMUNOLOGY 2011; 186:6417-26. [PMID: 21515789 DOI: 10.4049/jimmunol.1001241] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We hypothesize that innate immune signals from infectious organisms and/or injured tissues may activate peripheral neuronal pain signals. In this study, we demonstrated that TLRs 3, 7, and 9 are expressed by human dorsal root ganglion neurons (DRGNs) and in cultures of primary mouse DRGNs. Stimulation of murine DRGNs with TLR ligands induced expression and production of proinflammatory chemokines and cytokines CCL5 (RANTES), CXCL10 (IP-10), IL-1α, IL-1β, and PGE(2), which have previously been shown to augment pain. Further, TLR ligands upregulated the expression of a nociceptive receptor, transient receptor potential vanilloid type 1 (TRPV1), and enhanced calcium flux by TRPV1-expressing DRGNs. Using a tumor-induced temperature sensitivity model, we showed that in vivo administration of a TLR9 antagonist, known as a suppressive oligodeoxynucleotide, blocked tumor-induced temperature sensitivity. Taken together, these data indicate that stimulation of peripheral neurons by TLR ligands can induce nerve pain.
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Affiliation(s)
- Jia Qi
- Laboratory of Molecular Immunoregulation, Cancer and Inflammatory Program, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, MD 21702, USA
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18
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Dai H, Navath RS, Balakrishnan B, Guru BR, Mishra MK, Romero R, Kannan RM, Kannan S. Intrinsic targeting of inflammatory cells in the brain by polyamidoamine dendrimers upon subarachnoid administration. Nanomedicine (Lond) 2011; 5:1317-29. [PMID: 21128716 DOI: 10.2217/nnm.10.89] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
AIM Understanding the interactions between nanomaterials and disease processes is crucial for designing effective therapeutic approaches. This article explores the unusual neuroinflammation targeting of dendrimers (with no targeting ligands) in the brain, with significant consequences for nanoscale materials in medicine. METHOD The in vivo biodistribution of fluorescent-labeled neutral generation-4- polyamidoamine dendrimers (∼4 nm) in a rabbit model of cerebral palsy was explored following subarachnoid administration. RESULTS These dendrimers, with no targeting ligands, were localizing in activated microglia and astrocytes (cells responsible for neuroinflammation), even in regions far moved from the site of injection, in newborn rabbits with maternal inflammation-induced cerebral palsy. CONCLUSION This intrinsic ability of dendrimers to localize inactivated microglia and astrocytes can enable targeted delivery of therapeutics in disorders such as cerebral palsy, Alzheimer's and multiple sclerosis.
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Affiliation(s)
- Hui Dai
- Department of Pediatrics (Critical Care Medicine), Children's Hospital of Michigan, Wayne State University, Detroit, MI 48201, USA
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19
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Zheng J, Bizzozero OA. Reduced proteasomal activity contributes to the accumulation of carbonylated proteins in chronic experimental autoimmune encephalomyelitis. J Neurochem 2010; 115:1556-67. [PMID: 20950414 PMCID: PMC2996488 DOI: 10.1111/j.1471-4159.2010.07062.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
We have recently shown that several carbonylated proteins, including glial fibrillary acidic protein, β-actin and β-tubulin, accumulate within cerebellar astrocytes during the chronic phase of myelin-oligodendrocyte glycoprotein (MOG)(35-55) peptide-induced experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. As protein carbonyls cannot be repaired and there is less oxidative stress in chronic than in acute EAE, we hypothesized that the accumulation of carbonylated proteins in these animals may be due to a defect in the degradation of the modified proteins. Alternatively, oxidized proteins in chronic EAE mice may be more resistant to proteolysis. Using lipopolysaccharide-stimulated astrocytes and several protease inhibitors we identified the 20S proteasome as the proteolytic system responsible for the elimination of most oxidized proteins. We also discovered that the chymotrysin-like and caspase-like activities of the 20S proteasome are impaired in chronic EAE, while the amount of proteasome was unchanged. Proteasome failure in these animals was confirmed by the build-up of ubiquitinated proteins, mostly within astrocytes. In a cell-free system, carbonylated proteins from EAE mice with acute and chronic disease seem to be equally sensitive to proteasomal degradation. Altogether, the results support the notion that diminished activity of the 20S proteasome is a major contributor to the accumulation of carbonylated proteins in astrocytes of chronic EAE mice.
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Affiliation(s)
- Jianzheng Zheng
- Department of Cell Biology and Physiology, University of New Mexico - Health Sciences Center, Albuquerque, New Mexico, USA
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20
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Thompson KA, Varrone JJ, Jankovic-Karasoulos T, Wesselingh SL, McLean CA. Cell-specific temporal infection of the brain in a simian immunodeficiency virus model of human immunodeficiency virus encephalitis. J Neurovirol 2010; 15:300-11. [PMID: 19593698 DOI: 10.1080/13550280903030125] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Increasing evidence supports early brain infection by human immunodeficiency virus (HIV). Definitive temporal studies determining when and within which brain cells viral DNA is present are lacking. This study utilized simian immunodeficiency virus (SIV)-infected macaques sacrificed at days 10, 21, 56, and 84 post inoculation. Laser-microdissection isolated pure perivascular macrophage, parenchymal microglia, and astrocyte populations. Nested polymerase chain reaction (PCR) and sequencing determined the presence and characteristics of SIV V3 and V1 env DNA from each population. At day 10, SIV DNA was detected in perivascular macrophage and astrocytes but not parenchymal microglia. gp41 expression was restricted to perivascular macrophage. At day 21, SIV DNA was not detected in any cell type. At day 56, SIV DNA was detectable in perivascular macrophage from one of two macaques, with no gp41 expression detected. At day 84 (morphologic and clinical encephalitis), SIV DNA was detected in all cell types, gp41 was only detected in perivascular macrophage and parenchymal microglia. The neurovirulent molecular clone, SIV/17E-Fr, was the only genotype identified in the brain cell populations. Early, productive brain SIV infection was transient and restricted to trafficking perivascular macrophage. During the nonencephalitic stage, there was a period of time when no SIV DNA could be detected in the brain cell populations. SIV was then seen to reenter the brain via infected perivascular macrophage, leading to productive infection of brain parenchymal macrophage/microglia with a terminal phase of encephalitis. These data challenge current notions of a HIV reservoir within latently infected, semipermanent brain cells and has significant implications for the timing and design of therapies to prevent HIV encephalitis (HIVE).
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Affiliation(s)
- Katherine A Thompson
- Department of Anatomical Pathology, The Alfred Hospital, Melbourne, Victoria, Australia.
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21
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Fuller S, Steele M, Münch G. Activated astroglia during chronic inflammation in Alzheimer's disease--do they neglect their neurosupportive roles? Mutat Res 2010; 690:40-49. [PMID: 19748514 DOI: 10.1016/j.mrfmmm.2009.08.016] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2009] [Revised: 08/08/2009] [Accepted: 08/15/2009] [Indexed: 05/28/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder, characterized histopathologically by the extracellular deposition of beta-amyloid peptide in senile plaques, as well as intracellular neurofibrillary tangles (NFT) of hyperphosphorylated tau protein, extensive neuronal loss and synaptic changes in the hippocampus and cerebral cortex. In addition, the AD brain shows chronic inflammation characterized by an abundance of reactive astrocytes and activated microglia. In the healthy brain, astrocytes provide essential services for brain homeostasis and neuronal function, including metabolic support for neurons in the form of lactate, glutamate uptake and conversion into glutamine, and synthesis of glutathione and its precursors. In AD, a large body of evidence now suggests that by transforming from a basal to a reactive state, astrocytes neglect their neurosupportive functions, thus rendering neurons vulnerable to neurotoxins including pro-inflammatory cytokines and reactive oxygen species. This review will explain the normal functions of astrocytes, and how these cells might be activated to turn into inflammatory cells, actively contributing to neurodegeneration and neglecting their neurosupportive roles ("neuro-neglect hypothesis"). Furthermore, it is proposed that astrocytes might be promising target of therapeutic intervention for Alzheimer's disease, if these compromised functions can be normalized with pharmacological agents that are specifically designed to return astrocytes to a quiescent phenotype or supplement factors which activated astrocytes lack to produce.
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Affiliation(s)
- Stacey Fuller
- Department of Pharmacology, School of Medicine, University of Western Sydney, Campbelltown, Australia
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22
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Bjelobaba I, Lavrnja I, Parabucki A, Stojkov D, Stojiljkovic M, Pekovic S, Nedeljkovic N. The cortical stab injury induces beading of fibers expressing ecto-nucleoside triphosphate diphosphohydrolase 3. Neuroscience 2010; 170:107-16. [PMID: 20620196 DOI: 10.1016/j.neuroscience.2010.06.063] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Revised: 06/24/2010] [Accepted: 06/24/2010] [Indexed: 01/03/2023]
Abstract
The ecto-nucleoside triphosphate diphosphohydrolase 3 (NTPDase3), an enzyme involved in degradation of extracellular adenosine triphosphate (ATP), is expressed on nerve fibers in different brain regions, including cortex. Here we studied the expression and role of this enzyme after unilateral cortical stab injury in rats. In cortical sections of control rats, NTPDase3 immunoreactivity was associated with two types of fibers: thin processes, occasionally with small mushroom-like protrusions and slightly thicker fibers with more pronounced and more frequent varicosities, whereas immunopositive neuronal perycaria were never observed. Although NTPDase3-positive thin processes and thicker fibers, by general appearance, size and shape, could be dendrites and axons, respectively, they were never immunopositive for microtubule associated protein-2 or neurofilament H subunit. Cortical stab injury induced rapid (within 4 hours) focal varicose swelling that evolved over time to prominent beading of NTPDase3-positive fibers. The NTPDase3-positive fibers in all experimental groups also abundantly express NTPDase1, ecto-5'-nucleotidase and P2X2 receptor channels. Because the brain injury causes a massive ATP release, it is reasonable to conclude that purinoreceptors and ectonucleotidases play an important role in the process of neuritic beading.
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Affiliation(s)
- I Bjelobaba
- Department for Neurobiology, Institute for Biological Research "Sinisa Stankovic", University of Belgrade, Bulevar Despota Stefana 142, 11000 Belgrade, Republic of Serbia.
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23
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Black JA, Newcombe J, Waxman SG. Astrocytes within multiple sclerosis lesions upregulate sodium channel Nav1.5. Brain 2010; 133:835-46. [PMID: 20147455 DOI: 10.1093/brain/awq003] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Astrocytes are prominent participants in the response of the central nervous system to injury, including neuroinflammatory insults. Rodent astrocytes in vitro have been shown to express voltage-gated sodium channels in a dynamic manner, with a switch in expression of tetrodotoxin-sensitive to tetrodotoxin-resistant channels in reactive astrocytes. However, the expression of sodium channels in human astrocytes has not been studied, and it is not known whether there are changes in the expression of sodium channels in reactive astrocytes of the human central nervous system. Here, we demonstrate a focal and robust upregulation of sodium channel Nav1.5 in reactive astrocytes at the borders of, and within, active and chronic multiple sclerosis lesions. Nav1.5 was only detectable at very low levels in astrocytes within multiple sclerosis macroscopically normal-appearing white matter or in normal control brain. Nav1.1, Nav1.2, Nav1.3 and Nav1.6 showed little or no expression in astrocytes within normal control tissue and limited upregulation in active multiple sclerosis lesions. Nav1.5 was also expressed at high levels in astrocytes in tissue surrounding new and old cerebrovascular accidents and brain tumours. These results demonstrate the expression of Nav1.5 in human astrocytes and show that Nav1.5 expression is dynamic in these cells. Our observations suggest that the upregulated expression of Nav1.5 in astrocytes may provide a compensatory mechanism, which supports sodium/potassium pump-dependent ionic homoeostasis in areas of central nervous system injury.
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Affiliation(s)
- Joel A Black
- Neuroscience Research Centre (Bldg 34), VA Connecticut Healthcare System (127A), 950 Campbell Avenue, West Haven, CT 06516, USA
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24
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Kampmann E, Johann S, van Neerven S, Beyer C, Mey J. Anti-inflammatory effect of retinoic acid on prostaglandin synthesis in cultured cortical astrocytes. J Neurochem 2008; 106:320-32. [PMID: 18394023 DOI: 10.1111/j.1471-4159.2008.05395.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Prostanoids are important mediators of inflammation and pain signaling. Although it is now well accepted that astrocytes participate in inflammatory reactions in the CNS, the molecular regulation of this activity is still largely unknown. Specifically, the regulation of prostanoid synthesis by this type of glia remains to be resolved. Recent evidence suggests that the transcriptional regulator retinoic acid (RA) is involved in regulation of the immune response. We have investigated the expression pattern of the enzymes that catalyze prostanoid and leukotriene synthesis in cultured cortical astrocytes, their stimulation by lipopolysaccharides (LPS) and their regulation by RA. The data indicate that astrocytes are an important source of prostaglandins (PGs) and that RA reduces their inflammatory biosynthesis. LPS treatment induced the expression of enzymes for the production of arachidonic acid and PGs but caused down-regulation of a PG degrading enzyme and of leukotriene synthesizing enzymes that compete with PG synthesis. Consequently, the secretion of the PGE(2) was highly increased after LPS exposure. RA counteracted the inflammatory regulation of cyclooxygenase (COX)-2 mRNA and protein in astrocytes and thereby reduced the synthesis of PGE(2) by approximately 60%. In the absence of LPS, RA enhanced the expression of COX-1 mRNA. In conclusion, RA might be effective in suppressing inflammatory processes in the brain by inhibiting PG synthesis.
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25
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de Guzman RC, VandeVord PJ. Variations in astrocyte and fibroblast response due to biomaterial particulates in vitro. J Biomed Mater Res A 2008; 85:14-24. [PMID: 17668862 DOI: 10.1002/jbm.a.31516] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The possible involvement of orthopedic biomaterial particles such as cobalt-chrome alloy (Co-Cr), ultrahigh molecular weight polyethylene (UHMWPE), titanium alloy (Ti-6Al-4V), and polymethyl methacrylate (PMMA) in the formation of glial and meningeal scars was investigated using an in vitro system. Cell lines were used as models for astrocytes and meningeal fibroblasts. They were incubated with varying concentrations of particle suspensions, after which proliferative and cytotoxic responses were quantified using MTT assay and Live/Dead microscopy. It was determined that relative particulate toxicity (arranged in decreasing order) to astrocytes is Co-Cr > Ti-6Al-4V > PMMA > UHMWPE, and toxicity to fibroblasts is PMMA > Co-Cr > Ti-6Al-4V > UHMWPE. Cell death caused by PMMA was mainly due to necrosis, while the rest of the particles induced apoptosis. Low quantities of Co-Cr and Ti-6Al-4V stimulate increased astrocyte proliferation rate. However, only the cells treated with titanium alloy caused upregulated transcription of reactive astrocyte markers such as glial fibrillary acidic protein, vimentin, nestin, and type IV collagen, suggesting the potential of titanium alloy alone to trigger glial scarring. None of the biomaterials tested promoted proliferation in fibroblasts implying that biomaterial particles are not directly involved in meningeal scar development.
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Affiliation(s)
- Roche C de Guzman
- Department of Biomedical Engineering, Wayne State University, Detroit, Michigan 48202, USA.
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26
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Lovelace MD, Cahill DM. A rapid cell counting method utilising acridine orange as a novel discriminating marker for both cultured astrocytes and microglia. J Neurosci Methods 2007; 165:223-9. [PMID: 17662460 DOI: 10.1016/j.jneumeth.2007.06.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Revised: 06/10/2007] [Accepted: 06/11/2007] [Indexed: 12/12/2022]
Abstract
Cell culture analyses of growth, morphology and apoptosis commonly require counting of different cell types stained with antibodies to discriminate between them. Previously, we reported the use of l-Leucine methyl ester (l-LME) to prepare purified cultures of type 1 astrocytes with minimal microglia, and staining by GFAP and CD antibodies, respectively. Here, we demonstrate a novel use of acridine orange (AO) for rapid discrimination between these cell types using fluorescence microscopy. AO accumulates in the lysosomes and also binds strongly to nuclear DNA and cytoplasmic/nucleolar RNA. Microglia may contain abundant lysosomes due to known roles in homeostasis and immune response. AO staining of lysosomes was tested at a range of concentrations, and 2.5 microg/mL was most suitable. In agreement with previous reports, microglia treated with AO showed very intense yellow, orange or red granular cytoplasmic staining of lysosomes. Microglia contain a substantially higher number of lysosomes than astrocytes, which have a variable amount. We measured the microglia population at 5.14+/-0.50% in mixed cultures. Thus, these results show AO is a novel discriminatory marker, as microglia were easily observed and counted in clumps on top of the monolayer of astrocytes, providing a rapid alternative to time-consuming and costly antibody-based assays.
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Affiliation(s)
- Michael D Lovelace
- School of Life and Environmental Sciences, Deakin University, Pigdons Road, Waurn Ponds, Victoria 3217, Australia
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27
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Ito U, Kawakami E, Nagasao J, Kuroiwa T, Nakano I, Oyanagi K. Restitution of ischemic injuries in penumbra of cerebral cortex after temporary ischemia. ACTA NEUROCHIRURGICA. SUPPLEMENT 2006; 96:239-43. [PMID: 16671462 DOI: 10.1007/3-211-30714-1_51] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We investigated, at both light and ultrastructural levels, the fate of swollen astrocytes and remodeling of neurites connected to disseminated, dying neurons in the ischemic neocortical penumbra. Specimens from left cerebral cortex were cut coronally at the infundibulum and observed by light and electron microscopy. We measured synapses and spines, and the thickness of neuritic trunks in the neuropil on electron microscopy photos. We also determined percent volume of axon terminals and spines by Weibel's point-counting method. Astrocytic swelling gradually subsided from day 4 after the ischemic insult, with increases in cytoplasmic glial fibrils and GFAP-positive astrocytes. Disseminated dying electron-dense neurons were fragmented by invading astrocytic cell processes and accumulated as granular pieces. The number of synapses and spines and total percent volume of axon terminals and spines decreased with an increasing sparsity of synaptic vesicles until day 4. One to 12 weeks after the ischemic insult, these values increased to or exceeded control values, and sprouting and increased synaptic vesicles were seen. Axons that had been attached to the dying neurons appeared to have shifted their connections to the spines and the neurites of the surviving neurons, increasing their thickness. Astrocytic restitution and neuronal remodeling processes started at 4 days continuing until 12 weeks after ischemic insult.
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Affiliation(s)
- U Ito
- Department of Neuropathology, Tokyo Metropolitan Institute for Neuroscience, Tokyo, Japan.
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28
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E-NTPDases in human airways: Regulation and relevance for chronic lung diseases. Purinergic Signal 2006; 2:399-408. [PMID: 18404479 PMCID: PMC2096640 DOI: 10.1007/s11302-006-9001-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2005] [Accepted: 12/21/2005] [Indexed: 12/01/2022] Open
Abstract
Chronic obstructive lung diseases are characterized by the inability to prevent bacterial infection and a gradual loss of lung function caused by recurrent inflammatory responses. In the past decade, numerous studies have demonstrated the importance of nucleotide-mediated bacterial clearance. Their interaction with P2 receptors on airway epithelia provides a rapid ‘on-and-off’ signal stimulating mucus secretion, cilia beating activity and surface hydration. On the other hand, abnormally high ATP levels resulting from damaged epithelia and bacterial lysis may cause lung edema and exacerbate inflammatory responses. Airway ATP concentrations are regulated by ecto nucleoside triphosphate diphosphohydrolases (E-NTPDases) which are expressed on the mucosal surface and catalyze the sequential dephosphorylation of nucleoside triphosphates to nucleoside monophosphates (ATP → ADP → AMP). The common bacterial product, Pseudomonas aeruginosa lipopolysaccharide (LPS), induces an acute reduction in azide-sensitive E-NTPDase activities, followed by a sustained increase in activity as well as NTPDase 1 and NTPDase 3 expression. Accordingly, chronic lung diseases, including cystic fibrosis (CF) and primary ciliary dyskinesia, are characterized by higher rates of nucleotide elimination, azide-sensitive E-NTPDase activities and expression. This review integrates the biphasic regulation of airway E-NTPDases with the function of purine signaling in lung diseases. During acute insults, a transient reduction in E-NTPDase activities may be beneficial to stimulate ATP-mediated bacterial clearance. In chronic lung diseases, elevating E-NTPDase activities may represent an attempt to prevent P2 receptor desensitization and nucleotide-mediated lung damage.
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29
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Herber DL, Maloney JL, Roth LM, Freeman MJ, Morgan D, Gordon MN. Diverse microglial responses after intrahippocampal administration of lipopolysaccharide. Glia 2006; 53:382-91. [PMID: 16288481 DOI: 10.1002/glia.20272] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Inflammation has been argued to play a primary role in the pathogenesis of Alzheimer's disease by contributing to the development of neuropathology and clinical symptoms. However, the mechanisms underlying these effects remain obscure. Lipopolysaccharide (LPS) activates the innate immune response and triggers gliosis when injected into the central nervous system. In the studies described in the present work, we evaluated the time course of microgliosis after a single intrahippocampal injection of LPS. Mice were injected bilaterally with 4 mug of LPS. Post-injection survival times were 1, 6, and 24 h, as well as 3, 7, 14, and 28 days. Protein and RNA analyses were performed for inflammatory markers. Significant elevations of cluster differentiation marker CD45, glial fibrillary acidic protein (GFAP), scavenger receptor A (SRA), and Fcgamma receptor mRNA were seen after 24 h. Immunohistochemistry revealed a complex pattern of protein expression by microglia, as well as changes in cell morphologies. RNA and protein for Fcgamma receptor and SRA were transiently elevated, peaked at 3 days, and returned to basal levels after 1 week. In contrast, microglia remained significantly activated through the 28-day time point, as determined by CD45 and complement receptor 3 levels. These findings indicate a multivariate response to LPS, and evaluation of microglial phenotypes may lead to a better understanding of neuroinflammatory diseases.
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Affiliation(s)
- Donna L Herber
- Department of Pharmacology and Therapeutics, Alzheimer Research Laboratory, University of South Florida, Tampa, USA
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30
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Herber DL, Roth LM, Wilson D, Wilson N, Mason JE, Morgan D, Gordon MN. Time-dependent reduction in Abeta levels after intracranial LPS administration in APP transgenic mice. Exp Neurol 2005; 190:245-53. [PMID: 15473997 DOI: 10.1016/j.expneurol.2004.07.007] [Citation(s) in RCA: 119] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Revised: 06/23/2004] [Accepted: 07/21/2004] [Indexed: 10/26/2022]
Abstract
Inflammation has been argued to play a primary role in the pathogenesis of Alzheimer's disease (AD). Lipopolysaccharide (LPS) activates the innate immune system, triggering gliosis and inflammation when injected in the central nervous system. In studies described here, APP transgenic mice were injected intrahippocampally with 4 or 10 microg of LPS and evaluated 1, 3, 7, 14, or 28 days later. Abeta load was significantly reduced at 3, 7, and 14 days but surprisingly returned near baseline 28 days after the injection. No effects of LPS on congophilic amyloid deposits could be detected. LPS also activated both microglia and astrocytes in a time-dependent manner. The GFAP astrocyte reaction and the Fcgamma receptor microglial reaction peaked at 7 days after LPS injection, returning to baseline by 2 weeks postinjection. When stained for CD45, microglial activation was detected at all time points, although the morphology of these cells transitioned from an ameboid to a ramified and bushy appearance between 7 and 14 days postinjection. These results indicate that activation of brain glia can rapidly and transiently clear diffuse Abeta deposits but has no effect on compacted fibrillar amyloid.
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Affiliation(s)
- Donna L Herber
- Alzheimer Research Laboratory, Department of Pharmacology and Therapeutics, University of South Florida, Tampa, FL 33612-4799, USA
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Esen N, Tanga FY, DeLeo JA, Kielian T. Toll-like receptor 2 (TLR2) mediates astrocyte activation in response to the Gram-positive bacterium Staphylococcus aureus. J Neurochem 2004; 88:746-58. [PMID: 14720224 DOI: 10.1046/j.1471-4159.2003.02202.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Astrocytes play an important role in initiating and regulating CNS immune responses through the release of proinflammatory cytokines and chemokines. Here we demonstrate that primary astrocytes are capable of recognizing the Gram-positive bacterium Staphylococcus aureus and its cell wall product peptidoglycan (PGN) and respond by producing numerous proinflammatory mediators including interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-1beta (MIP-1beta), MIP-2, and monocyte chemoattractant protein (MCP-1). Astrocytes have recently been shown to express Toll-like receptor 2 (TLR2), a pattern recognition receptor important for recognizing structural components of various Gram-positive bacteria, fungi, and protozoa. However, the functional significance of TLR2 in mediating astrocyte activation remains unknown. Primary astrocytes from TLR2 knockout mice were used to evaluate the role of TLR2 in astrocyte responses to S. aureus and PGN. The results demonstrate that TLR2 is essential for maximal proinflammatory cytokine and chemokine production, but not phagocytosis, in primary astrocytes following S. aureus and PGN exposure. In addition, both stimuli led to a significant increase in TLR2 mRNA expression in wild-type astrocytes as assessed by real-time quantitative RT-PCR. These findings suggest that astrocytes may play a key role in the initial antibacterial immune response in the CNS through engagement of TLR2.
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Affiliation(s)
- Nilufer Esen
- Department of Neurobiology and Developmental Science, University of Arkansas for Medical Sciences, Little Rock 72205, USA
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Fuller KM, Arriaga EA. Analysis of individual acidic organelles by capillary electrophoresis with laser-induced fluorescence detection facilitated by the endocytosis of fluorescently labeled microspheres. Anal Chem 2003; 75:2123-30. [PMID: 12720351 DOI: 10.1021/ac026476d] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Submicrometer-sized fluorescent microspheres were loaded into the acidic organelles of NS-1 mouse myeloma cells via endocytosis. Confocal microscopy imaging showed that microspheres colocalized nearly perfectly with LysoTracker Red, a probe that stains acidic organelles. Unlike LysoTracker dyes that seem to leak from acidic organelles upon cell disruption, microspheres are retained within these organelles, facilitating their analysis following isolation. Using capillary electrophoresis (CE) with laser-induced fluorescence detection (LIF), the electrophoretic mobilities of acidic organelles were individually calculated and fluorescence intensities individually measured. When cells were incubated for sufficient time to allow for endocytosis (48 h) with 3.9 x 10(3) microspheres/cell, replicate CE-LIF analyses of the corresponding isolated fraction indicated a dramatic increase in the number of detected events (n = 1990 +/- 234) and in the overall fluorescence intensity of the individual events (0.38 +/- 0.01 RFU; average +/- SD; n = 3) over the corresponding <10-min incubations (n = 60; 0.21 RFU, respectively). In addition, a treatment with 4-fold increase in microsphere density (1.6 x 10(4) microspheres/cell), increased the number of detected individual events (n = 3427 +/- 101) and altered only slightly the fluorescence intensity and electrophoretic mobility distributions. The individual electrophoretic mobility values ranged from -1.45 x 10(-)(4) to -3.0 x 10(-)(4) cm(2) V(-)(1) s(-)(1) while the individual fluorescence values ranged from 0.1 V to over 8 V, demonstrating the benefit of detecting organelles individually rather than averaging their properties over single cells or bulk homogenates.
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Affiliation(s)
- Kathryn M Fuller
- Department of Chemistry, University of Minnesota, Minneapolis 55455, USA
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Dogan MD, Ataoglu H, Akarsu ES. Effects of selective cyclooxygenase enzyme inhibitors on lipopolysaccharide-induced dual thermoregulatory changes in rats. Brain Res Bull 2002; 57:179-85. [PMID: 11849824 DOI: 10.1016/s0361-9230(01)00739-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The effects of selective cyclooxygenase-1 and cyclooxygenase-2 inhibitors (valeryl salicylate and SC-58236, respectively) on Escherichia coli O111:B4 lipopolysaccharide (LPS)-induced dual thermoregulatory changes and serum tumor necrosis factor-alpha elevation were investigated in rats. LPS (50 microg/kg, intraperitoneal) produced an initial hypothermia that was then followed by fever. Serum tumor necrosis factor-alpha levels elevated at the initial phase of hypothermia. Valeryl salicylate injections (20, 40, and 80 mg/kg, subcutaneous [s.c.]) completely inhibited hypothermia without any effect on the elevated serum tumor necrosis factor-alpha levels and on the subsequent fever. On the other hand, SC-58236 injections (10, 20, and 40 mg/kg, s.c.) only partially abolished the hypothermia. SC-58236 had no effect on the initiation of fever, however completely inhibited the maintenance of fever. The serum tumor necrosis factor-alpha elevation was not reduced by SC-58236 treatment. The combination of valeryl salicylate and SC-58236 also failed to inhibit the initiation of fever. These findings suggest that cycloxygenase-1 may have a predominant role for the development of LPS-induced hypothermia, but cyclooxygenase-1 does not seem to be involved in the mediation of LPS-induced fever. Meanwhile, cyclooxgenase-2 may be critical for the late phase rather than the initiation of the fever response in rats.
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Affiliation(s)
- M Devrim Dogan
- Department of Pharmacology and Clinical Pharmacology, Faculty of Medicine, Ankara University, Sihhiye 06100 Ankara, Turkey
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