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Witton J, Brady ES, Craig MT. Sleep-based neuronal oscillations as a physiological biomarker for Alzheimer's disease: is night time the right time? Neural Regen Res 2024; 19:1417-1418. [PMID: 38051875 PMCID: PMC10883485 DOI: 10.4103/1673-5374.386412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Accepted: 09/06/2023] [Indexed: 12/07/2023] Open
Affiliation(s)
- Jonathan Witton
- Department of Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter, Exeter, England, UK
| | - Erica S Brady
- Gladstone Institute for Neurological Disease, San Francisco, CA, USA
| | - Michael T Craig
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, Scotland, UK
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Francis VI, Liddle C, Camacho E, Kulkarni M, Junior SRS, Harvey JA, Ballou ER, Thomson DD, Brown GD, Hardwick JM, Casadevall A, Witton J, Coelho C. Cryptococcus neoformans rapidly invades the murine brain by sequential breaching of airway and endothelial tissues barriers, followed by engulfment by microglia. mBio 2024; 15:e0307823. [PMID: 38511961 PMCID: PMC11005363 DOI: 10.1128/mbio.03078-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 02/29/2024] [Indexed: 03/22/2024] Open
Abstract
Cryptococcus neoformans causes lethal meningitis and accounts for approximately 10%-15% of AIDS-associated deaths worldwide. There are major gaps in our understanding of how this fungus invades the mammalian brain. To investigate the dynamics of C. neoformans tissue invasion, we mapped fungal localization and host cell interactions in infected brain, lung, and upper airways using mouse models of systemic and airway infection. To enable this, we developed an in situ imaging pipeline capable of measuring large volumes of tissue while preserving anatomical and cellular information by combining thick tissue sections, tissue clarification, and confocal imaging. We confirm high fungal burden in mouse upper airway after nasal inoculation. Yeast in turbinates were frequently titan cells, with faster kinetics than reported in mouse lungs. Importantly, we observed one instance of fungal cells enmeshed in lamina propria of the upper airways, suggesting penetration of airway mucosa as a possible route of tissue invasion and dissemination to the bloodstream. We extend previous literature positing bloodstream dissemination of C. neoformans, by finding viable fungi in the bloodstream of mice a few days after intranasal infection. As early as 24 h post systemic infection, the majority of C. neoformans cells traversed the blood-brain barrier, and were engulfed or in close proximity to microglia. Our work presents a new method for investigating microbial invasion, establishes that C. neoformans can breach multiple tissue barriers within the first days of infection, and demonstrates microglia as the first cells responding to C. neoformans invasion of the brain.IMPORTANCECryptococcal meningitis causes 10%-15% of AIDS-associated deaths globally. Still, brain-specific immunity to cryptococci is a conundrum. By employing innovative imaging, this study reveals what occurs during the first days of infection in brain and in airways. We found that titan cells predominate in upper airways and that cryptococci breach the upper airway mucosa, which implies that, at least in mice, the upper airways are a site for fungal dissemination. This would signify that mucosal immunity of the upper airway needs to be better understood. Importantly, we also show that microglia, the brain-resident macrophages, are the first responders to infection, and microglia clusters are formed surrounding cryptococci. This study opens the field to detailed molecular investigations on airway immune response, how fungus traverses the blood-brain barrier, how microglia respond to infection, and ultimately how microglia monitor the blood-brain barrier to preserve brain function.
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Affiliation(s)
- Vanessa I. Francis
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
- Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
| | - Corin Liddle
- Bioimaging Facility, University of Exeter, Exeter, United Kingdom
| | - Emma Camacho
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Madhura Kulkarni
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | | | - Jamie A. Harvey
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
| | - Elizabeth R. Ballou
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
| | - Darren D. Thomson
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
| | - Gordon D. Brown
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
- Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
| | - J. Marie Hardwick
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Arturo Casadevall
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jonathan Witton
- Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
| | - Carolina Coelho
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, United Kingdom
- Faculty of Health and Life Sciences, University of Exeter, Exeter, United Kingdom
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3
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Francis VI, Liddle C, Camacho E, Kulkarni M, Junior SRS, Harvey JA, Ballou ER, Thomson DD, Hardwick JM, Casadevall A, Witton J, Coelho C. Cryptococcus neoformans rapidly invades the murine brain by sequential breaching of airway and endothelial tissues barriers, followed by engulfment by microglia. bioRxiv 2023:2023.11.13.564824. [PMID: 38014111 PMCID: PMC10680653 DOI: 10.1101/2023.11.13.564824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
The fungus Cryptococcus neoformans causes lethal meningitis in humans with weakened immune systems and is estimated to account for 10-15% of AIDS-associated deaths worldwide. There are major gaps in our understanding of how this environmental fungus evades the immune system and invades the mammalian brain before the onset of overt symptoms. To investigate the dynamics of C. neoformans tissue invasion, we mapped early fungal localisation and host cell interactions at early times in infected brain, lung, and upper airways using mouse models of systemic and airway infection. To enable this, we developed an in situ imaging pipeline capable of measuring large volumes of tissue while preserving anatomical and cellular information by combining thick tissue sections, tissue clarification, and confocal imaging. Made possible by these techniques, we confirm high fungal burden in mouse upper airway turbinates after nasal inoculation. Surprisingly, most yeasts in turbinates were titan cells, indicating this microenvironment enables titan cell formation with faster kinetics than reported in mouse lungs. Importantly, we observed one instance of fungal cells enmeshed in lamina propria of upper airways, suggesting penetration of airway mucosa as a possible route of tissue invasion and dissemination to the bloodstream. We extend previous literature positing bloodstream dissemination of C. neoformans, via imaging C. neoformans within blood vessels of mouse lungs and finding viable fungi in the bloodstream of mice a few days after intranasal infection, suggesting that bloodstream access can occur via lung alveoli. In a model of systemic cryptococcosis, we show that as early as 24 h post infection, majority of C. neoformans cells traversed the blood-brain barrier, and are engulfed or in close proximity to microglia. Our work establishes that C. neoformans can breach multiple tissue barriers within the first days of infection. This work presents a new method for investigating cryptococcal invasion mechanisms and demonstrates microglia as the primary cells responding to C. neoformans invasion.
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Affiliation(s)
- Vanessa I Francis
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, EX4 4QD, UK
- Faculty of Health and Life Sciences, University of Exeter, EX4 4QD, UK
| | - Corin Liddle
- Bioimaging Facility, University of Exeter, Exeter, EX4 4QD, UK
| | - Emma Camacho
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Madhura Kulkarni
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Samuel R S Junior
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jamie A Harvey
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, EX4 4QD, UK
| | - Elizabeth R Ballou
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, EX4 4QD, UK
| | - Darren D Thomson
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, EX4 4QD, UK
| | - J Marie Hardwick
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Arturo Casadevall
- Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jonathan Witton
- Faculty of Health and Life Sciences, University of Exeter, EX4 4QD, UK
| | - Carolina Coelho
- MRC Centre for Medical Mycology at University of Exeter, University of Exeter, Exeter, EX4 4QD, UK
- Faculty of Health and Life Sciences, University of Exeter, EX4 4QD, UK
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Brady ES, Griffiths J, Andrianova L, Bielska M, Saito T, Saido TC, Randall AD, Tamagnini F, Witton J, Craig MT. Alterations to parvalbumin-expressing interneuron function and associated network oscillations in the hippocampal - medial prefrontal cortex circuit during natural sleep in App NL-G-F/NL-G-F mice. Neurobiol Dis 2023; 182:106151. [PMID: 37172910 DOI: 10.1016/j.nbd.2023.106151] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 05/07/2023] [Accepted: 05/09/2023] [Indexed: 05/15/2023] Open
Abstract
In the early stages of Alzheimer's disease (AD), the accumulation of the peptide amyloid-β (Aβ) damages synapses and disrupts neuronal activity, leading to the disruption of neuronal oscillations associated with cognition. This is thought to be largely due to impairments in CNS synaptic inhibition, particularly via parvalbumin (PV)-expressing interneurons that are essential for generating several key oscillations. Research in this field has largely been conducted in mouse models that over-express humanised, mutated forms of AD-associated genes that produce exaggerated pathology. This has prompted the development and use of knock-in mouse lines that express these genes at an endogenous level, such as the AppNL-G-F/NL-G-F mouse model used in the present study. These mice appear to model the early stages of Aβ-induced network impairments, yet an in-depth characterisation of these impairments in currently lacking. Therefore, using 16 month-old AppNL-G-F/NL-G-F mice, we analysed neuronal oscillations found in the hippocampus and medial prefrontal cortex (mPFC) during awake behaviour, rapid eye movement (REM) and non-REM (NREM) sleep to assess the extent of network dysfunction. No alterations to gamma oscillations were found to occur in the hippocampus or mPFC during either awake behaviour, REM or NREM sleep. However, during NREM sleep an increase in the power of mPFC spindles and decrease in the power of hippocampal sharp-wave ripples was identified. The latter was accompanied by an increase in the synchronisation of PV-expressing interneuron activity, as measured using two-photon Ca2+ imaging, as well as a decrease in PV-expressing interneuron density. Furthermore, although changes were detected in local network function of mPFC and hippocampus, long-range communication between these regions appeared intact. Altogether, our results suggest that these NREM sleep-specific impairments represent the early stages of circuit breakdown in response to amyloidopathy.
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Affiliation(s)
- Erica S Brady
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Prince of Wales Road, Exeter EX4 4PS, England, UK; Gladstone Institute for Neurological Disease, 1650 Owens Street, San Francisco, CA 91458, United States of America
| | - Jessica Griffiths
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Prince of Wales Road, Exeter EX4 4PS, England, UK; School of Pharmacy, University of Reading, Whiteknights, Reading RG6 6LA, UK
| | - Lilya Andrianova
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Prince of Wales Road, Exeter EX4 4PS, England, UK; School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Monika Bielska
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
| | - Takashi Saito
- Department of Neurocognitive Science, Institute of Brain Science, Nagoya City University Graduate School of Medical Sciences, Japan
| | - Takaomi C Saido
- Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science, Saitama 351-0198, Japan
| | - Andrew D Randall
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Prince of Wales Road, Exeter EX4 4PS, England, UK; School of Physiology and Pharmacology, University of Bristol, Bristol BS8 1TD, UK
| | - Francesco Tamagnini
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Prince of Wales Road, Exeter EX4 4PS, England, UK; School of Pharmacy, University of Reading, Whiteknights, Reading RG6 6LA, UK
| | - Jonathan Witton
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Prince of Wales Road, Exeter EX4 4PS, England, UK.
| | - Michael T Craig
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Prince of Wales Road, Exeter EX4 4PS, England, UK; School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
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Ridler T, Witton J, Phillips KG, Randall A, Brown JT. Correction: Impaired speed encoding and grid cell periodicity in a mouse model of tauopathy. eLife 2023; 12:e87504. [PMID: 36881015 PMCID: PMC9991047 DOI: 10.7554/elife.87504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023] Open
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Walsh C, Ridler T, Margetts-Smith G, Garcia Garrido M, Witton J, Randall AD, Brown JT. β Bursting in the Retrosplenial Cortex Is a Neurophysiological Correlate of Environmental Novelty Which Is Disrupted in a Mouse Model of Alzheimer's Disease. J Neurosci 2022; 42:7094-7109. [PMID: 35927034 PMCID: PMC9480878 DOI: 10.1523/jneurosci.0890-21.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2021] [Revised: 07/15/2022] [Accepted: 07/18/2022] [Indexed: 11/21/2022] Open
Abstract
The retrosplenial cortex (RSC) plays a significant role in spatial learning and memory and is functionally disrupted in the early stages of Alzheimer's disease (AD). In order to investigate neurophysiological correlates of spatial learning and memory in this region we employed in vivo electrophysiology in awake and freely moving male mice, comparing neural activity between wild-type and J20 mice, a transgenic model of AD-associated amyloidopathy. To determine the response of the RSC to environmental novelty local field potentials (LFPs) were recorded while mice explored novel and familiar recording arenas. In familiar environments we detected short, phasic bursts of β (20-30 Hz) oscillations (β bursts), which arose at a low but steady rate. Exposure to a novel environment rapidly initiated a dramatic increase in the rate, size and duration of β bursts. Additionally, θ-α/β cross-frequency coupling was significantly higher during novelty, and spiking of neurons in the RSC was significantly enhanced during β bursts. Finally, excessive β bursting was seen in J20 mice, including increased β bursting during novelty and familiarity, yet a loss of coupling between β bursts and spiking activity. These findings support the concept that β bursting may be responsible for the activation and reactivation of neuronal ensembles underpinning the formation and maintenance of cortical representations, and that disruptions to this activity in J20 mice may underlie cognitive impairments seen in these animals.SIGNIFICANCE STATEMENT The retrosplenial cortex (RSC) is thought to be involved in the formation, recall and consolidation of contextual memory. The discovery of bursts of β oscillations in this region, which are associated with increased neuronal spiking and strongly upregulated while mice explore novel environments, provides a potential mechanism for the activation of neuronal ensembles, which may underlie the formation of cortical representations of context. Excessive β bursting in the RSC of J20 mice, a mouse model of Alzheimer's disease (AD), alongside the disassociation of β bursting from neuronal spiking, may underlie spatial memory impairments previously shown in these mice. These findings introduce a novel neurophysiological correlate of spatial learning and memory, and a potentially new form of AD-related cortical dysfunction.
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Affiliation(s)
- Callum Walsh
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Hatherly Laboratories, Exeter EX4 4PS, United Kingdom
| | - Thomas Ridler
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Hatherly Laboratories, Exeter EX4 4PS, United Kingdom
| | - Gabriella Margetts-Smith
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Hatherly Laboratories, Exeter EX4 4PS, United Kingdom
| | - Maria Garcia Garrido
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Hatherly Laboratories, Exeter EX4 4PS, United Kingdom
| | - Jonathan Witton
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Hatherly Laboratories, Exeter EX4 4PS, United Kingdom
| | - Andrew D Randall
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Hatherly Laboratories, Exeter EX4 4PS, United Kingdom
| | - Jonathan T Brown
- Department of Clinical and Biomedical Sciences, University of Exeter Medical School, Hatherly Laboratories, Exeter EX4 4PS, United Kingdom
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Craig MT, Witton J. A cellular switchboard in memory circuits. Science 2022; 377:262-263. [DOI: 10.1126/science.add2681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Neurogliaform cells can direct the flow of information through the hippocampus
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Affiliation(s)
- Michael T. Craig
- School of Psychology and Neuroscience, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Jonathan Witton
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
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Meftah S, Witton J, Cavallini A, Murray TK, Jankowski L, Bose S, Ashby M, Brown JT. Identifying early markers of synaptic dysfunction in a mouse model of tauopathy. Alzheimers Dement 2020. [DOI: 10.1002/alz.040342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Soraya Meftah
- University of Exeter Exeter United Kingdom
- University of Bristol Bristol United Kingdom
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Ridler T, Witton J, Phillips KG, Randall AD, Brown JT. Impaired speed encoding and grid cell periodicity in a mouse model of tauopathy. eLife 2020; 9:59045. [PMID: 33242304 PMCID: PMC7690954 DOI: 10.7554/elife.59045] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 11/16/2020] [Indexed: 12/13/2022] Open
Abstract
Dementia is associated with severe spatial memory deficits which arise from dysfunction in hippocampal and parahippocampal circuits. For spatially sensitive neurons, such as grid cells, to faithfully represent the environment these circuits require precise encoding of direction and velocity information. Here, we have probed the firing rate coding properties of neurons in medial entorhinal cortex (MEC) in a mouse model of tauopathy. We find that grid cell firing patterns are largely absent in rTg4510 mice, while head-direction tuning remains largely intact. Conversely, neural representation of running speed information was significantly disturbed, with smaller proportions of MEC cells having firing rates correlated with locomotion in rTg4510 mice. Additionally, the power of local field potential oscillations in the theta and gamma frequency bands, which in wild-type mice are tightly linked to running speed, was invariant in rTg4510 mice during locomotion. These deficits in locomotor speed encoding likely severely impact path integration systems in dementia.
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Affiliation(s)
- Thomas Ridler
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, Hatherly LaboratoriesExeterUnited Kingdom
| | - Jonathan Witton
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, Hatherly LaboratoriesExeterUnited Kingdom
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, University WalkBristolUnited Kingdom
| | - Keith G Phillips
- Lilly United Kingdom Erl Wood Manor WindleshamSurreyUnited Kingdom
| | - Andrew D Randall
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, Hatherly LaboratoriesExeterUnited Kingdom
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, University WalkBristolUnited Kingdom
| | - Jonathan T Brown
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, Hatherly LaboratoriesExeterUnited Kingdom
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Jackson JS, Witton J, Johnson JD, Ahmed Z, Ward M, Randall AD, Hutton ML, Isaac JT, O'Neill MJ, Ashby MC. Altered Synapse Stability in the Early Stages of Tauopathy. Cell Rep 2017; 18:3063-3068. [PMID: 28355559 PMCID: PMC5382238 DOI: 10.1016/j.celrep.2017.03.013] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 10/22/2016] [Accepted: 03/01/2017] [Indexed: 11/30/2022] Open
Abstract
Synapse loss is a key feature of dementia, but it is unclear whether synaptic dysfunction precedes degenerative phases of the disease. Here, we show that even before any decrease in synapse density, there is abnormal turnover of cortical axonal boutons and dendritic spines in a mouse model of tauopathy-associated dementia. Strikingly, tauopathy drives a mismatch in synapse turnover; postsynaptic spines turn over more rapidly, whereas presynaptic boutons are stabilized. This imbalance between pre- and post-synaptic stability coincides with reduced synaptically driven neuronal activity in pre-degenerative stages of the disease. Density of cortical axonal boutons and dendritic spines is reduced early in tauopathy Abnormalities in synaptic stability and size exist before decreases in synapse density Turnover of dendritic spines is elevated, whereas presynaptic boutons are stabilized Neuronal activity is reduced at stages associated with mismatched synaptic turnover
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Affiliation(s)
| | - Jonathan Witton
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - James D Johnson
- Lilly UK, Erl Wood Manor, Windlesham, Surrey GU20 6PH, UK; Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | - Zeshan Ahmed
- Lilly UK, Erl Wood Manor, Windlesham, Surrey GU20 6PH, UK
| | - Mark Ward
- Lilly UK, Erl Wood Manor, Windlesham, Surrey GU20 6PH, UK
| | - Andrew D Randall
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK
| | | | - John T Isaac
- Lilly UK, Erl Wood Manor, Windlesham, Surrey GU20 6PH, UK
| | | | - Michael C Ashby
- Centre for Synaptic Plasticity, School of Physiology, Pharmacology and Neuroscience, University of Bristol, Biomedical Sciences Building, University Walk, Bristol BS8 1TD, UK.
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Witton J, Padmashri R, Zinyuk LE, Popov VI, Kraev I, Line SJ, Jensen TP, Tedoldi A, Cummings DM, Tybulewicz VLJ, Fisher EMC, Bannerman DM, Randall AD, Brown JT, Edwards FA, Rusakov DA, Stewart MG, Jones MW. Hippocampal circuit dysfunction in the Tc1 mouse model of Down syndrome. Nat Neurosci 2015; 18:1291-1298. [PMID: 26237367 PMCID: PMC4552261 DOI: 10.1038/nn.4072] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 06/29/2015] [Indexed: 12/11/2022]
Abstract
Hippocampal pathology is likely to contribute to cognitive disability in Down syndrome, yet the neural network basis of this pathology and its contributions to different facets of cognitive impairment remain unclear. Here we report dysfunctional connectivity between dentate gyrus and CA3 networks in the transchromosomic Tc1 mouse model of Down syndrome, demonstrating that ultrastructural abnormalities and impaired short-term plasticity at dentate gyrus-CA3 excitatory synapses culminate in impaired coding of new spatial information in CA3 and CA1 and disrupted behavior in vivo. These results highlight the vulnerability of dentate gyrus-CA3 networks to aberrant human chromosome 21 gene expression and delineate hippocampal circuit abnormalities likely to contribute to distinct cognitive phenotypes in Down syndrome.
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Affiliation(s)
- J Witton
- School of Physiology & Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - R Padmashri
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - L E Zinyuk
- School of Physiology & Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - V I Popov
- Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Reg. 142290, Russia.,The Open University, Department of Life Sciences, Walton Hall, Milton Keynes, MK7 6AA, UK
| | - I Kraev
- The Open University, Department of Life Sciences, Walton Hall, Milton Keynes, MK7 6AA, UK
| | - S J Line
- Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, UK
| | - T P Jensen
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - A Tedoldi
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - D M Cummings
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - V L J Tybulewicz
- MRC National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK
| | - E M C Fisher
- Department of Neurodegenerative Disease, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - D M Bannerman
- Department of Experimental Psychology, University of Oxford, Oxford OX1 3UD, UK
| | - A D Randall
- School of Physiology & Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - J T Brown
- School of Physiology & Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - F A Edwards
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, UK
| | - D A Rusakov
- Department of Clinical and Experimental Epilepsy, UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.,Laboratory of Brain Microcircuits, Institute of Biology and Biomedicine, University of Nizhny Novgorod, Nizhny Novgorod 603950, Russia
| | - M G Stewart
- The Open University, Department of Life Sciences, Walton Hall, Milton Keynes, MK7 6AA, UK
| | - M W Jones
- School of Physiology & Pharmacology, University of Bristol, University Walk, Bristol BS8 1TD, UK
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Witton J, Staniaszek LE, Bartsch U, Randall AD, Jones MW, Brown JT. Disrupted hippocampal sharp-wave ripple-associated spike dynamics in a transgenic mouse model of dementia. J Physiol 2015; 594:4615-30. [PMID: 25480798 DOI: 10.1113/jphysiol.2014.282889] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 11/24/2014] [Indexed: 12/12/2022] Open
Abstract
KEY POINTS High frequency (100-250 Hz) neuronal oscillations in the hippocampus, known as sharp-wave ripples (SWRs), synchronise the firing behaviour of groups of neurons and play a key role in memory consolidation. Learning and memory are severely compromised in dementias such as Alzheimer's disease; however, the effects of dementia-related pathology on SWRs are unknown. The frequency and temporal structure of SWRs was disrupted in a transgenic mouse model of tauopathy (one of the major hallmarks of several dementias). Excitatory pyramidal neurons were more likely to fire action potentials in a phase-locked manner during SWRs in the mouse model of tauopathy; conversely, inhibitory interneurons were less likely to fire phase-locked spikes during SWRs. These findings indicate there is reduced inhibitory control of hippocampal network events and point to a novel mechanism which may underlie the cognitive impairments in this model of dementia. ABSTRACT Neurons within the CA1 region of the hippocampus are co-activated during high frequency (100-250 Hz) sharp-wave ripple (SWR) activity in a manner that probably drives synaptic plasticity and promotes memory consolidation. In this study we have used a transgenic mouse model of dementia (rTg4510 mice), which overexpresses a mutant form of tau protein, to examine the effects of tauopathy on hippocampal SWRs and associated neuronal firing. Tetrodes were used to record simultaneous extracellular action potentials and local field potentials from the dorsal CA1 pyramidal cell layer of 7- to 8-month-old wild-type and rTg4510 mice at rest in their home cage. At this age point these mice exhibit neurofibrillary tangles, neurodegeneration and cognitive deficits. Epochs of sleep or quiet restfulness were characterised by minimal locomotor activity and a low theta/delta ratio in the local field potential power spectrum. SWRs detected off-line were significantly lower in amplitude and had an altered temporal structure in rTg4510 mice. Nevertheless, the average frequency profile and duration of the SWRs were relatively unaltered. Putative interneurons displayed significantly less temporal and phase locking to SWRs in rTg4510 mice, whilst putative pyramidal neurons showed increased temporal and phase locking to SWRs. These findings indicate there is reduced inhibitory control of hippocampal network events and point to a novel mechanism which may contribute to impairments in memory consolidation in this model of dementia.
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Affiliation(s)
- Jonathan Witton
- School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Lydia E Staniaszek
- Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, Hatherly Laboratories, Prince of Wales Road, Exeter, EX4 4PS, UK
| | - Ullrich Bartsch
- School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Andrew D Randall
- School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol, BS8 1TD, UK.,Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, Hatherly Laboratories, Prince of Wales Road, Exeter, EX4 4PS, UK
| | - Matthew W Jones
- School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol, BS8 1TD, UK
| | - Jonathan T Brown
- School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol, BS8 1TD, UK.,Institute of Biomedical and Clinical Sciences, University of Exeter Medical School, University of Exeter, Hatherly Laboratories, Prince of Wales Road, Exeter, EX4 4PS, UK
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Rodríguez JJ, Noristani HN, Hilditch T, Olabarria M, Yeh CY, Witton J, Verkhratsky A. Increased densities of resting and activated microglia in the dentate gyrus follow senile plaque formation in the CA1 subfield of the hippocampus in the triple transgenic model of Alzheimer's disease. Neurosci Lett 2013; 552:129-34. [PMID: 23827221 DOI: 10.1016/j.neulet.2013.06.036] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 06/20/2013] [Indexed: 01/01/2023]
Abstract
Alzheimer's disease (AD) is an irreversible neurodegenerative disease that is characterised by the presence of β-amyloid (Aβ) plaques, neurofibrillary tangles (NFTs) and synaptic loss specifically in brain regions involved in learning and memory such as the neocortex and the hippocampus. Aβ depositions in the form of neuritic plaques trigger activation of microglia that is believed to be a common neuropathological feature of AD brains. As an integral part of the hippocampus, the dentate gyrus (DG) plays an important role in cognitive function. Although post-mortem studies suggest later involvement of the DG into the AD progression, changes in microglia have not been studied in this subfield of the hippocampus. In the present study the numerical density (Nv, #/mm(3)) of both resting (identified by tomato lectin staining) and activated (identified by Mac-1 immunoreactivity) microglia was analysed in the molecular layer (ML) of the DG in the triple transgenic (3xTg-AD) mouse model of AD at different ages (9, 12 and 18 months). The 3xTg-AD mouse model of AD showed a significant increase in the Nv of resting (by 75%) and activated (by 67%) at 18 months of age compared to non-Tg controls. These results indicate a complex microglial remodelling during AD progression.
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Affiliation(s)
- J J Rodríguez
- Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain; Department of Neurosciences, University of the Basque Country UPV/EHU, 48940 Leioa, Spain.
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Forsyth LH, Witton J, Brown JT, Randall AD, Jones MW. In Vitro and In Vivo Recording of Local Field Potential Oscillations in Mouse Hippocampus. ACTA ACUST UNITED AC 2012; 2:273-94. [PMID: 26069015 DOI: 10.1002/9780470942390.mo120089] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Oscillations in hippocampal local field potentials (LFP) reflect the coordinated, rhythmic activity of constituent interneuronal and principal cell populations. Quantifying changes in oscillatory patterns and power therefore provides a powerful metric through which to infer mechanisms and functions of hippocampal network activity at the mesoscopic level, bridging single-neuron studies to behavioral assays of hippocampal function. Here, complementary protocols that enable mechanistic analyses of oscillation generation in vitro (in slices and a whole hippocampal preparation) and functional analyses of hippocampal circuits in behaving mice are described. Used together, these protocols provide a comprehensive view of hippocampal phenotypes in mouse models, highlighting oscillatory biomarkers of hippocampal function and dysfunction. Curr. Protoc. Mouse Biol. 2:273-294 © 2012 by John Wiley & Sons, Inc.
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Affiliation(s)
- L H Forsyth
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - J Witton
- Pfizer Applied Neurophysiology Group, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - J T Brown
- Pfizer Applied Neurophysiology Group, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - A D Randall
- Pfizer Applied Neurophysiology Group, School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - M W Jones
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
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Rodríguez JJ, Witton J, Olabarria M, Noristani HN, Verkhratsky A. Increase in the density of resting microglia precedes neuritic plaque formation and microglial activation in a transgenic model of Alzheimer's disease. Cell Death Dis 2011; 1:e1. [PMID: 21364611 PMCID: PMC3032511 DOI: 10.1038/cddis.2009.2] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The formation of cerebral senile plaques composed of amyloid β peptide (Aβ) is a fundamental feature of Alzheimer's disease (AD). Glial cells and more specifically microglia become reactive in the presence of Aβ. In a triple transgenic model of AD (3 × Tg-AD), we found a significant increase in activated microglia at 12 (by 111%) and 18 (by 88%) months of age when compared with non-transgenic (non-Tg) controls. This microglial activation correlated with Aβ plaque formation, and the activation in microglia was closely associated with Aβ plaques and smaller Aβ deposits. We also found a significant increase in the area density of resting microglia in 3 × Tg-AD animals both at plaque-free stage (at 9 months by 105%) and after the development of A plaques (at 12 months by 54% and at 18 months by 131%). Our results show for the first time that the increase in the density of resting microglia precedes both plaque formation and activation of microglia by extracellular Aβ accumulation. We suggest that AD pathology triggers a complex microglial reaction: at the initial stages of the disease the number of resting microglia increases, as if in preparation for the ensuing activation in an attempt to fight the extracellular Aβ load that is characteristic of the terminal stages of the disease.
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Affiliation(s)
- J J Rodríguez
- Faculty of Life Sciences, The University of Manchester, Manchester, UK.
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Witton J, Brown JT, Jones MW, Randall AD. Altered synaptic plasticity in the mossy fibre pathway of transgenic mice expressing mutant amyloid precursor protein. Mol Brain 2010; 3:32. [PMID: 21040543 PMCID: PMC2988062 DOI: 10.1186/1756-6606-3-32] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 11/01/2010] [Indexed: 01/05/2023] Open
Abstract
Aβ peptides derived from the cleavage of amyloid precursor protein are widely believed to play an important role in the pathophysiology of Alzheimer's disease. A common way to study the impact of these molecules on CNS function is to compare the physiology of transgenic mice that overproduce Aβ with non-transgenic animals. In the hippocampus, this approach has been frequently applied to the investigation of synaptic transmission and plasticity in the perforant and Schaffer collateral commissural pathways, the first and third components of the classical hippocampal trisynaptic circuit, respectively. Similar studies however have not been carried out on the remaining component of the trisynaptic circuit, the mossy fibre pathway. Using transverse hippocampal slices prepared from ~2 year old animals we have compared mossy fibre synaptic function in wild-type mice and their Tg2576 littermates which age-dependently overproduce Aβ. Input-output curves were not altered in slices from Tg2576 mice, but these animals exhibited a significant loss of the prominent frequency-facilitation expressed by the mossy fibre pathway. In addition to this change in short term synaptic plasticity, high frequency stimulation-induced, NMDA-receptor-independent LTP was absent in slices from the transgenic mice. These data represent the first description of functional deficits in the mossy fibre pathway of Aβ-overproducing transgenic mice.
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Affiliation(s)
- Jonathan Witton
- School of Physiology and Pharmacology, University of Bristol, University Walk, Bristol, BS8 1TD, UK
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Randall AD, Witton J, Booth C, Hynes-Allen A, Brown JT. The functional neurophysiology of the amyloid precursor protein (APP) processing pathway. Neuropharmacology 2010; 59:243-67. [PMID: 20167227 DOI: 10.1016/j.neuropharm.2010.02.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 01/12/2023]
Abstract
Amyloid beta (Abeta) peptides derived from proteolytic cleavage of amyloid precursor protein (APP) are thought to be a pivotal toxic species in the pathogenesis of Alzheimer's disease (AD). Furthermore, evidence has been accumulating that components of APP processing pathway are involved in non-pathological normal function of the CNS. In this review we aim to cover the extensive body of research aimed at understanding how components of this pathway contribute to neurophysiological function of the CNS in health and disease. We briefly outline changes to clinical neurophysiology seen in AD patients before discussing functional changes in mouse models of AD which range from changes to basal synaptic transmission and synaptic plasticity through to abnormal synchronous network activity. We then describe the various neurophysiological actions that are produced by application of exogenous Abeta in various forms, and finally discuss a number or other neurophysiological aspects of the APP pathway, including functional activities of components of secretase complexes other than Abeta production.
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Affiliation(s)
- A D Randall
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol School of Medical Sciences, Bristol, UK.
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Manning VC, Strathdee G, Best D, Keaney F, Mcgillivray L, Witton J. Dual diagnosis screening: preliminary findings on the comparison of 50 clients attending community mental health services and 50 clients attending community substance misuse services. Journal of Substance Use 2009. [DOI: 10.1080/14659890215691] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Affiliation(s)
- J Strang
- National Addiction Centre, Institute of Psychiatry, King's College London, London SE5 8AF.
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