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Sekulic-Jablanovic M, Wright MB, Petkovic V, Bodmer D. Pioglitazone Ameliorates Gentamicin Ototoxicity by Affecting the TLR and STAT Pathways in the Early Postnatal Organ of Corti. Front Cell Neurosci 2020; 14:566148. [PMID: 33192313 PMCID: PMC7658481 DOI: 10.3389/fncel.2020.566148] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 09/25/2020] [Indexed: 12/20/2022] Open
Abstract
Noise trauma, infection, and ototoxic drugs are frequent external causes of hearing loss. With no pharmacological treatments currently available, understanding the mechanisms and pathways leading to auditory hair cell (HC) damage and repair is crucial for identifying potential pharmacological targets. Prior research has implicated increased reactive oxygen species (ROS) and inflammation as general mechanisms of hearing loss common to diverse causes. Novel targets of these two key mechanisms of auditory damage may provide new paths toward the prevention and treatment of hearing loss. Pioglitazone, an oral antidiabetic drug from the class of thiazolidinediones, acts as an agonist of the peroxisome proliferator-activated receptor-gamma (PPAR-γ) and is involved in the regulation of lipid and glucose metabolism. PPAR-γ is an important player in repressing the expression of inflammatory cytokines and signaling molecules. We evaluated the effects of pioglitazone in the mouse Organ of Corti (OC) explants to characterize its influence on signaling pathways involved in auditory HC damage. The OC explants was cultured with pioglitazone, gentamicin, or a combination of both agents. Pioglitazone treatment resulted in significant repression of interferon (IFN)-α and -gamma pathways and downstream cytokines, as assessed by RNA sequencing and quantitative PCR gene expression assays. More detailed investigation at the single gene and protein level showed that pioglitazone mediated its anti-inflammatory effects through alterations of the Toll-like receptor (TLR) and STAT pathways. Together, these results indicate that pioglitazone significantly represses IFN and TLR in the cochlea, dampening the activity of gentamicin-induced pathways. These data support our previous results demonstrating significant protection of auditory HCs in the OC explants exposed to pioglitazone and other PPAR-targeted agents.
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Affiliation(s)
| | | | - Vesna Petkovic
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Daniel Bodmer
- Department of Biomedicine, University of Basel, Basel, Switzerland.,Clinic for Otolaryngology, Head and Neck Surgery, University Hospital Basel, Basel, Switzerland
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2
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The peroxisome proliferator-activated receptor gamma (PPARγ) agonist, rosiglitazone, ameliorates neurofunctional and neuroinflammatory abnormalities in a rat model of Gulf War Illness. PLoS One 2020; 15:e0242427. [PMID: 33186383 PMCID: PMC7665704 DOI: 10.1371/journal.pone.0242427] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/03/2020] [Indexed: 12/12/2022] Open
Abstract
Background Gulf War (GW) Illness (GWI) is a debilitating condition with a complex constellation of immune, endocrine and neurological symptoms, including cognitive impairment, anxiety and depression. We studied a novel model of GWI based on 3 known common GW exposures (GWE): (i) intranasal lipopolysaccharide, to which personnel were exposed during desert sand storms; (ii) pyridostigmine bromide, used as prophylaxis against chemical warfare; and (iii) chronic unpredictable stress, an inescapable element of war. We used this model to evaluate prophylactic treatment with the PPARγ agonist, rosiglitazone (ROSI). Methods Rats were subjected to the three GWE for 33 days. In series 1 and 2, male and female GWE-rats were compared to naïve rats. In series 3, male rats with GWE were randomly assigned to prophylactic treatment with ROSI (GWE-ROSI) or vehicle. After the 33-day exposures, three neurofunctional domains were evaluated: cognition (novel object recognition), anxiety-like behaviors (elevated plus maze, open field) and depression-like behaviors (coat state, sucrose preference, splash test, tail suspension and forced swim). Brains were analyzed for astrocytic and microglial activation and neuroinflammation (GFAP, Iba1, tumor necrosis factor and translocator protein). Neurofunctional data from rats with similar exposures were pooled into 3 groups: naïve, GWE and GWE-ROSI. Results Compared to naïve rats, GWE-rats showed significant abnormalities in the three neurofunctional domains, along with significant neuroinflammation in amygdala and hippocampus. There were no differences between males and females with GWE. GWE-ROSI rats showed significant attenuation of neuroinflammation and of some of the neurofunctional abnormalities. Conclusion This novel GWI model recapitulates critical neurofunctional abnormalities reported by Veterans with GWI. Concurrent prophylactic treatment with ROSI was beneficial in this model.
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Edison P, Donat CK, Sastre M. In vivo Imaging of Glial Activation in Alzheimer's Disease. Front Neurol 2018; 9:625. [PMID: 30131755 PMCID: PMC6090997 DOI: 10.3389/fneur.2018.00625] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 07/10/2018] [Indexed: 12/12/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by memory loss and decline of cognitive function, associated with progressive neurodegeneration. While neuropathological processes like amyloid plaques and tau neurofibrillary tangles have been linked to neuronal death in AD, the precise role of glial activation on disease progression is still debated. It was suggested that neuroinflammation could occur well ahead of amyloid deposition and may be responsible for clearing amyloid, having a neuroprotective effect; however, later in the disease, glial activation could become deleterious, contributing to neuronal toxicity. Recent genetic and preclinical studies suggest that the different activation states of microglia and astrocytes are complex, not as polarized as previously thought, and that the heterogeneity in their phenotype can switch during disease progression. In the last few years, novel imaging techniques e.g., new radiotracers for assessing glia activation using positron emission tomography and advanced magnetic resonance imaging technologies have emerged, allowing the correlation of neuro-inflammatory markers with cognitive decline, brain function and brain pathology in vivo. Here we review all new imaging technology in AD patients and animal models that has the potential to serve for early diagnosis of the disease, to monitor disease progression and to test the efficacy and the most effective time window for potential anti-inflammatory treatments.
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Affiliation(s)
- Paul Edison
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
| | - Cornelius K Donat
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
| | - Magdalena Sastre
- Division of Brain Sciences, Department of Medicine, Imperial College London, London, United Kingdom
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4
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Waldron AM, Wyffels L, Verhaeghe J, Richardson JC, Schmidt M, Stroobants S, Langlois X, Staelens S. Longitudinal Characterization of [18F]-FDG and [18F]-AV45 Uptake in the Double Transgenic TASTPM Mouse Model. J Alzheimers Dis 2018; 55:1537-1548. [PMID: 27911309 PMCID: PMC5181675 DOI: 10.3233/jad-160760] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We aimed to monitor the timing of amyloid-β deposition in relation to changes in brain function using in vivo imaging with [18F]-AV45 and [18F]-FDG in a mouse model of Alzheimer’s disease. TASTPM transgenic mice and wild-type controls were scanned longitudinally with [18F]-AV45 and [18F]-FDG before (3 months of age) and at multiple time points after the onset of amyloid deposition (6, 9, 12, and 15 months of age). As expected with increasing amyloidosis, TASTPM mice demonstrated progressive age-dependent increases in [18F]-AV45 uptake that were significantly higher than for WT from 9 months onwards and correlated to ex vivo measures of amyloid burden. The metabolism of [18F]-AV45 produces several brain penetrant radiometabolites and normalization to a reference region helps to negate this non-specific binding and improve the sensitivity of [18F]-AV45. The observed trajectory of [18F]-FDG alterations deviated from our proposed hypothesis of gradual decreases with worsening amyloidosis. While [18F]-FDG uptake in TASTPM mice was significantly lower than that of WT at 9 months, reduced [18F]-FDG was not associated with aging in TASTPM mice. Moreover, [18F]-FDG uptake did not correlate to measures of ex vivo amyloid burden. Our findings suggest that while amyloid-β is sufficient to induce hypometabolism, these pathologies are not linked in a dose-dependent manner in TASTPM mice.
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Affiliation(s)
- Ann-Marie Waldron
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | - Leonie Wyffels
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium.,Department of Nuclear Medicine, University Hospital Antwerp, Antwerp, Belgium
| | - Jeroen Verhaeghe
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
| | | | - Mark Schmidt
- Department of Neuroscience, Janssen Pharmaceutica NV, Beerse, Belgium
| | - Sigrid Stroobants
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium.,Department of Nuclear Medicine, University Hospital Antwerp, Antwerp, Belgium
| | - Xavier Langlois
- Department of Neuroscience, Janssen Pharmaceutica NV, Beerse, Belgium
| | - Steven Staelens
- Molecular Imaging Center Antwerp, University of Antwerp, Antwerp, Belgium
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5
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James ML, Belichenko NP, Shuhendler AJ, Hoehne A, Andrews LE, Condon C, Nguyen TVV, Reiser V, Jones P, Trigg W, Rao J, Gambhir SS, Longo FM. [ 18F]GE-180 PET Detects Reduced Microglia Activation After LM11A-31 Therapy in a Mouse Model of Alzheimer's Disease. Theranostics 2017; 7:1422-1436. [PMID: 28529627 PMCID: PMC5436503 DOI: 10.7150/thno.17666] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 02/08/2017] [Indexed: 12/22/2022] Open
Abstract
Microglial activation is a key pathological feature of Alzheimer's disease (AD). PET imaging of translocator protein 18 kDa (TSPO) is a strategy to detect microglial activation in vivo. Here we assessed flutriciclamide ([18F]GE-180), a new second-generation TSPO-PET radiotracer, for its ability to monitor response to LM11A-31, a novel AD therapeutic in clinical trials. AD mice displaying pathology were treated orally with LM11A-31 for 3 months. Subsequent [18F]GE-180-PET imaging revealed significantly lower signal in cortex and hippocampus of LM11A-31-treated AD mice compared to those treated with vehicle, corresponding with decreased levels of TSPO immunostaining and microglial Iba1 immunostaining. In addition to detecting decreased microglial activation following LM11A-31 treatment, [18F]GE-180 identified activated microglia in AD mice with greater sensitivity than another second-generation TSPO radiotracer, [18F]PBR06. Together, these data demonstrate the promise of [18F]GE-180 as a potentially sensitive tool for tracking neuroinflammation in AD mice and for monitoring therapeutic modulation of microglial activation.
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Affiliation(s)
- Michelle L. James
- Department of Radiology, Stanford University, Stanford, 94305, USA
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, 94305, USA
| | - Nadia P. Belichenko
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, 94305, USA
| | | | - Aileen Hoehne
- Department of Radiology, Stanford University, Stanford, 94305, USA
| | | | - Christina Condon
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, 94305, USA
| | - Thuy-Vi V. Nguyen
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, 94305, USA
| | | | - Paul Jones
- GE Healthcare, Amersham HP7 9LL, United Kingdom
| | | | - Jianghong Rao
- Department of Radiology, Stanford University, Stanford, 94305, USA
| | | | - Frank M. Longo
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, 94305, USA
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6
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Mirzaei N, Tang SP, Ashworth S, Coello C, Plisson C, Passchier J, Selvaraj V, Tyacke RJ, Nutt DJ, Sastre M. In vivo imaging of microglial activation by positron emission tomography with [(11)C]PBR28 in the 5XFAD model of Alzheimer's disease. Glia 2016; 64:993-1006. [PMID: 26959396 DOI: 10.1002/glia.22978] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 02/08/2016] [Indexed: 11/05/2022]
Abstract
Microglial activation has been linked with deficits in neuronal function and synaptic plasticity in Alzheimer's disease (AD). The mitochondrial translocator protein (TSPO) is known to be upregulated in reactive microglia. Accurate visualization and quantification of microglial density by PET imaging using the TSPO tracer [(11)C]-R-PK11195 has been challenging due to the limitations of the ligand. In this study, it was aimed to evaluate the new TSPO tracer [(11)C]PBR28 as a marker for microglial activation in the 5XFAD transgenic mouse model of AD. Dynamic PET scans were acquired following intravenous administration of [(11)C]PBR28 in 6-month-old 5XFAD mice and in wild-type controls. Autoradiography with [(3)H]PBR28 was carried out in the same brains to further confirm the distribution of the radioligand. In addition, immunohistochemistry was performed on adjacent brain sections of the same mice to evaluate the co-localization of TSPO with microglia. PET imaging revealed that brain uptake of [(11)C]PBR28 in 5XFAD mice was increased compared with control mice. Moreover, binding of [(3)H]PBR28, measured by autoradiography, was enriched in cortical and hippocampal brain regions, coinciding with the positive staining of the microglial marker Iba-1 and amyloid deposits in the same areas. Furthermore, double-staining using antibodies against TSPO demonstrated co-localization of TSPO with microglia and not with astrocytes in 5XFAD mice and human post-mortem AD brains. The data provided support of the suitability of [(11)C]PBR28 as a tool for in vivo monitoring of microglial activation and assessment of treatment response in future studies using animal models of AD.
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Affiliation(s)
- Nazanin Mirzaei
- Division of Brain Sciences, Imperial College London, Du Cane Road, London, W12 0NN, United Kingdom
| | - Sac Pham Tang
- Imanova Limited, Du Cane Road, London, W12 0NN, United Kingdom
| | - Sharon Ashworth
- Imanova Limited, Du Cane Road, London, W12 0NN, United Kingdom
| | | | | | - Jan Passchier
- Imanova Limited, Du Cane Road, London, W12 0NN, United Kingdom
| | - Vimal Selvaraj
- Department of Animal Science, Cornell University, Ithaca, New York
| | - Robin J Tyacke
- Division of Brain Sciences, Imperial College London, Du Cane Road, London, W12 0NN, United Kingdom
| | - David J Nutt
- Division of Brain Sciences, Imperial College London, Du Cane Road, London, W12 0NN, United Kingdom
| | - Magdalena Sastre
- Division of Brain Sciences, Imperial College London, Du Cane Road, London, W12 0NN, United Kingdom
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7
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Heneka MT, Carson MJ, El Khoury J, Landreth GE, Brosseron F, Feinstein DL, Jacobs AH, Wyss-Coray T, Vitorica J, Ransohoff RM, Herrup K, Frautschy SA, Finsen B, Brown GC, Verkhratsky A, Yamanaka K, Koistinaho J, Latz E, Halle A, Petzold GC, Town T, Morgan D, Shinohara ML, Perry VH, Holmes C, Bazan NG, Brooks DJ, Hunot S, Joseph B, Deigendesch N, Garaschuk O, Boddeke E, Dinarello CA, Breitner JC, Cole GM, Golenbock DT, Kummer MP. Neuroinflammation in Alzheimer's disease. Lancet Neurol 2015; 14:388-405. [PMID: 25792098 DOI: 10.1016/s1474-4422(15)70016-5] [Citation(s) in RCA: 3630] [Impact Index Per Article: 403.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Increasing evidence suggests that Alzheimer's disease pathogenesis is not restricted to the neuronal compartment, but includes strong interactions with immunological mechanisms in the brain. Misfolded and aggregated proteins bind to pattern recognition receptors on microglia and astroglia, and trigger an innate immune response characterised by release of inflammatory mediators, which contribute to disease progression and severity. Genome-wide analysis suggests that several genes that increase the risk for sporadic Alzheimer's disease encode factors that regulate glial clearance of misfolded proteins and the inflammatory reaction. External factors, including systemic inflammation and obesity, are likely to interfere with immunological processes of the brain and further promote disease progression. Modulation of risk factors and targeting of these immune mechanisms could lead to future therapeutic or preventive strategies for Alzheimer's disease.
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Affiliation(s)
- Michael T Heneka
- Department of Neurology, University Hospital Bonn, University of Bonn, Bonn, Germany; German Center for Neurodegnerative Diseases (DZNE), Bonn, Germany.
| | - Monica J Carson
- Division of Biomedical Sciences, Center for Glial-Neuronal Interactions, University of California, Riverside, CA, USA
| | - Joseph El Khoury
- Division of Infectious Diseases, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA, USA
| | - Gary E Landreth
- Alzheimer Research Laboratory, Department of Neurosciences, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | | | | | - Andreas H Jacobs
- Department of Geriatrics, Johanniter Hospital, Bonn, Germany; European Institute for Molecular Imaging (EIMI) at the Westfalian Wilhelms University (WWU), Münster, Germany
| | - Tony Wyss-Coray
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA; Center for Tissue Regeneration, Repair, and Restoration, VA Palo Alto Health Care System, Palo Alto, CA, USA
| | - Javier Vitorica
- Instituto de Biomedicina de Sevilla (IBIS), Hospital Universitario Virgen del Rocio, Consejo Superior de Investigaciones Cientificas Universidad de Sevilla, Sevilla, Spain
| | - Richard M Ransohoff
- Department of Neuroscience, Neuroinflammation Research Center, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Karl Herrup
- Division of Life Science, Hong Kong University of Science and Technology, Hong Kong
| | - Sally A Frautschy
- Department of Neurology, David Geffen School of Medicine at the University of California, Los Angeles, the Geriatric, Research, and Clinical Center, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Bente Finsen
- Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark
| | - Guy C Brown
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Manchester, UK; Achucarro Center for Neuroscience, Basque Foundation for Science (IKERBASQUE), Bilbao, Spain; Department of Neurosciences, University of the Basque Country UPV/EHU (Euskal Herriko Unibertsitatea/Universidad del País Vasco) and CIBERNED (Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas), Leioa, Spain
| | - Koji Yamanaka
- Research Institute of Environmental Medicine, Nagoya University/RIKEN Brain Science Institute, Wako-shi, Japan
| | - Jari Koistinaho
- Department of Neurobiology, AI Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Eicke Latz
- German Center for Neurodegnerative Diseases (DZNE), Bonn, Germany; Institute of Innate Immunity, University of Bonn, Bonn, Germany; Department of InfectiousDiseases and Immunology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Annett Halle
- Max-Planck Research Group Neuroimmunology, Center of Advanced European Studies and Research (CAESAR), Bonn, Germany
| | - Gabor C Petzold
- Department of Neurology, University Hospital Bonn, University of Bonn, Bonn, Germany; German Center for Neurodegnerative Diseases (DZNE), Bonn, Germany
| | - Terrence Town
- Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Dave Morgan
- Department of Molecular Pharmacology and Physiology, Byrd Alzheimer's Institute, University of South Florida College of Medicine, Tampa, FL, USA
| | - Mari L Shinohara
- Department of Immunology, Duke University Medical Center, Durham, NC, USA
| | - V Hugh Perry
- School of Biological Sciences, Southampton General Hospital, Southampton, UK
| | - Clive Holmes
- Clinical and Experimental Science, University of Southampton, Southampton, UK; Memory Assessment and Research Centre, Moorgreen Hospital, Southern Health Foundation Trust, Southampton, UK
| | - Nicolas G Bazan
- Louisiana State University Neuroscience Center of Excellence, Louisiana State University Health Sciences Center School of Medicine in New Orleans, LA, USA
| | - David J Brooks
- Division of Experimental Medicine, Imperial College London, Hammersmith Hospital, London, UK
| | - Stéphane Hunot
- Centre National de la Recherche Scientifique (CNRS), UMR 7225, Experimental Therapeutics of Neurodegeneration, Paris, France
| | - Bertrand Joseph
- Department of Oncology Pathology, Cancer Centrum Karolinska, Karolinska Institutet, Stockholm, Sweden
| | - Nikolaus Deigendesch
- Department of Cellular Microbiology, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Olga Garaschuk
- Institute of Physiology II, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Erik Boddeke
- Department of Neuroscience, University of Groningen, University Medical Centre Groningen, Groningen, Netherlands
| | | | - John C Breitner
- Centre for Studies on Prevention of Alzheimer's Disease, Douglas Mental Health University Institute, and the McGill University Faculty of Medicine, Montreal, Quebec, Canada
| | - Greg M Cole
- Department of Neurology, David Geffen School of Medicine at the University of California, Los Angeles, the Geriatric, Research, and Clinical Center, Greater Los Angeles Veterans Affairs Healthcare System, Los Angeles, CA, USA
| | - Douglas T Golenbock
- Department of InfectiousDiseases and Immunology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Markus P Kummer
- Department of Neurology, University Hospital Bonn, University of Bonn, Bonn, Germany
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Birch AM, Katsouri L, Sastre M. Modulation of inflammation in transgenic models of Alzheimer's disease. J Neuroinflammation 2014; 11:25. [PMID: 24490742 PMCID: PMC3922595 DOI: 10.1186/1742-2094-11-25] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 01/21/2014] [Indexed: 12/23/2022] Open
Abstract
Over the past decade the process of inflammation has been a focus of increasing interest in the Alzheimer’s disease (AD) field, not only for its potential role in neuronal degeneration but also as a promising therapeutic target. However, recent research in this field has provided divergent outcomes, largely due to the use of different models and different stages of the disease when the investigations have been carried out. It is now accepted that microglia, and possibly astrocytes, change their activation phenotype during ageing and the stage of the disease, and therefore these are important factors to have in mind to define the function of different inflammatory components as well as potential therapies. Modulating inflammation using animal models of AD has offered the possibility to investigate inflammatory components individually and manipulate inflammatory genes in amyloid precursor protein and tau transgenics independently. This has also offered some hints on the mechanisms by which these factors may affect AD pathology. In this review we examine the different transgenic approaches and treatments that have been reported to modulate inflammation using animal models of AD. These studies have provided evidence that enhancing inflammation is linked with increases in amyloid-beta (Aβ) generation, Aβ aggregation and tau phosphorylation. However, the alterations on tau phosphorylation can be independent of changes in Aβ levels by these inflammatory mediators.
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Affiliation(s)
| | | | - Magdalena Sastre
- Division of Brain Sciences, Imperial College London, London W12 0NN, UK.
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9
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Miller TR, Wetter JB, Jarvis MF, Bitner RS. Spinal microglial activation in rat models of neuropathic and osteoarthritic pain: an autoradiographic study using [3H]PK11195. Eur J Pain 2012; 17:692-703. [PMID: 23070996 DOI: 10.1002/j.1532-2149.2012.00232.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2012] [Indexed: 12/13/2022]
Abstract
BACKGROUND Microglia serve as macrophage-like cells in the central nervous system, and activation of microglial cells in the spinal cord may contribute to ongoing pain following peripheral trauma or nerve injury. Following pronociceptive stimulation, activated microglia exhibit increased expression of the peripheral benzodiazepine receptor (PBR)/translocator protein 18 kDa (TSPO). METHODS Using radioligand binding autoradiography and filtration assays, we examined the specific binding of the PBR/TSPO ligand [(3)H]PK11195 in spinal cords from the following rat experimental pain models: neuropathic pain induced by spinal nerve ligation (SNL), osteoarthritic pain induced by intraarticular injection of monosodium iodoacetate in the knee joint (MIA-OA), and subchronic inflammatory pain induced by intraplantar injection of complete Freund's adjuvant (CFA). RESULTS Specific [(3)H]PK11195 binding in dorsal and ventral regions of lumbar spinal cord was increased by ≥70% ipsilateral to SNL. Also, specific [(3)H]PK11195 binding in the ipsilateral (injured) lumbar spinal cord was increased by approximately 25% in MIA-OA. In contrast to the data obtained in these chronic neuropathic and nociceptive pain models, specific [(3)H]PK11195 binding in the ipsilateral (injured) dorsal horn was elevated in only one of six CFA rats. Consistent with increased PBR/TSPO binding measured for SNL and MIA-OA rats, increased anti-OX-42 immunostaining of the cell surface microglial marker CD11b was observed in the ipsilateral spinal cord from these models. CONCLUSIONS These studies demonstrate that [(3)H]PK11195 binding assays may serve as a marker of spinal microglial activation in experimental models of chronic neuropathic or osteoarthritic pain, which may be translatable to clinical research through novel applications of PBR/TSPO imaging agents.
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Affiliation(s)
- T R Miller
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, Abbott Park, USA.
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10
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Solito E, Sastre M. Microglia function in Alzheimer's disease. Front Pharmacol 2012; 3:14. [PMID: 22363284 PMCID: PMC3277080 DOI: 10.3389/fphar.2012.00014] [Citation(s) in RCA: 232] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 01/21/2012] [Indexed: 01/11/2023] Open
Abstract
Contrary to early views, we now know that systemic inflammatory/immune responses transmit to the brain. The microglia, the resident “macrophages” of the brain’s innate immune system, are most responsive, and increasing evidence suggests that they enter a hyper-reactive state in neurodegenerative conditions and aging. As sustained over-production of microglial pro-inflammatory mediators is neurotoxic, this raises great concern that systemic inflammation (that also escalates with aging) exacerbates or possibly triggers, neurological diseases (Alzheimer’s, prion, motoneuron disease). It is known that inflammation has an essential role in the progression of Alzheimer’s disease (AD), since amyloid-β (Aβ) is able to activate microglia, initiating an inflammatory response, which could have different consequences for neuronal survival. On one hand, microglia may delay the progression of AD by contributing to the clearance of Aβ, since they phagocyte Aβ and release enzymes responsible for Aβ degradation. Microglia also secrete growth factors and anti-inflammatory cytokines, which are neuroprotective. In addition, microglia removal of damaged cells is a very important step in the restoration of the normal brain environment, as if left such cells can become potent inflammatory stimuli, resulting in yet further tissue damage. On the other hand, as we age microglia become steadily less efficient at these processes, tending to become over-activated in response to stimulation and instigating too potent a reaction, which may cause neuronal damage in its own right. Therefore, it is critical to understand the state of activation of microglia in different AD stages to be able to determine the effect of potential anti-inflammatory therapies. We discuss here recent evidence supporting both the beneficial or detrimental performance of microglia in AD, and the attempt to find molecules/biomarkers for early diagnosis or therapeutic interventions.
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Affiliation(s)
- Egle Solito
- Centre for Translational Medicine and Therapeutics, William Harvey Research Institute, Barts and The London, Queen Mary's School of Medicine and Dentistry London, UK
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11
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Sadaghiani MS, Javadi-Paydar M, Gharedaghi MH, Fard YY, Dehpour AR. Antidepressant-like effect of pioglitazone in the forced swimming test in mice: The role of PPAR-gamma receptor and nitric oxide pathway. Behav Brain Res 2011; 224:336-43. [DOI: 10.1016/j.bbr.2011.06.011] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 06/07/2011] [Accepted: 06/11/2011] [Indexed: 10/18/2022]
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Wang H, Pullambhatla M, Guilarte TR, Mease RC, Pomper MG. Synthesis of [(125)I]iodoDPA-713: a new probe for imaging inflammation. Biochem Biophys Res Commun 2009; 389:80-3. [PMID: 19703411 DOI: 10.1016/j.bbrc.2009.08.102] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2009] [Accepted: 08/17/2009] [Indexed: 11/19/2022]
Abstract
[(125)I]IodoDPA-713 [(125)I]1, which targets the translocator protein (TSPO, 18 kDa), was synthesized in seven steps from methyl-4-methoxybenzoate as a tool for quantification of inflammation in preclinical models. Preliminary in vitro autoradiography and in vivo small animal imaging were performed using [(125)I]1 in a neurotoxicant-treated rat and in a murine model of lung inflammation, respectively. The radiochemical yield of [(125)I]1 was 44+/-6% with a specific radioactivity of 51.8 GBq/micromol (1400 mCi/micromol) and >99% radiochemical purity. Preliminary studies showed that [(125)I]1 demonstrated increased specific binding to TSPO in a neurotoxicant-treated rat and increased radiopharmaceutical uptake in the lungs of an experimental inflammation model of lung inflammation. Compound [(125)I]1 is a new, convenient probe for preclinical studies of TSPO activity.
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Affiliation(s)
- Haofan Wang
- Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins Medical Institutions, Baltimore, MD 21231, USA
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