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Ji C, Yang X, Eleish M, Jiang Y, Tetlow A, Song S, Martín-Ávila A, Wu Q, Zhou Y, Gan W, Lin Y, Sigurdsson EM. Neuronal hypofunction and network dysfunction in a mouse model at an early stage of tauopathy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.29.591735. [PMID: 38746288 PMCID: PMC11092661 DOI: 10.1101/2024.04.29.591735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
We previously reported altered neuronal Ca 2+ dynamics in the motor cortex of 12-month-old JNPL3 tauopathy mice during quiet wakefulness or forced running, with a tau antibody treatment significantly restoring the neuronal Ca 2+ activity profile and decreasing pathological tau in these mice 1 . Whether neuronal functional deficits occur at an early stage of tauopathy and if tau antibody treatment is effective in younger tauopathy mice needed further investigation. In addition, neuronal network activity and neuronal firing patterns have not been well studied in behaving tauopathy models. In this study, we first performed in vivo two-photon Ca 2+ imaging in JNPL3 mice in their early stage of tauopathy at 6 months of age, compared to 12 month old mice and age-matched wild-type controls to evaluate neuronal functional deficits. At the animal level, frequency of neuronal Ca 2+ transients decreased only in 6 month old tauopathy mice compared to controls, and only when animals were running on a treadmill. The amplitude of neuronal transients decreased in tauopathy mice compared to controls under resting and running conditions in both age groups. Total neuronal activity decreased only in 6 month old tauopathy mice compared to controls under resting and running conditions. Within either tauopathy or wild-type group, only total activity decreased in older wild-type animals. The tauopathy mice at different ages did not differ in neuronal Ca 2+ transient frequency, amplitude or total activity. In summary, neuronal function did significantly attenuate at an early age in tauopathy mice compared to controls but interestingly did not deteriorate between 6 and 12 months of age. A more detailed populational analysis of the pattern of Ca 2+ activity at the neuronal level in the 6 month old cohort confirmed neuronal hypoactivity in layer 2/3 of primary motor cortex, compared to wild-type controls, when animals were either resting or running on a treadmill. Despite reduced activity, neuronal Ca 2+ profiles exhibited enhanced synchrony and dysregulated responses to running stimulus. Further ex vivo electrophysiological recordings revealed reduction of spontaneous excitatory synaptic transmission onto and in pyramidal neurons and enhanced excitability of inhibitory neurons in motor cortex, which were likely responsible for altered neuronal network activity in this region. Lastly, tau antibody treatment reduced pathological tau and gliosis partially restored the neuronal Ca 2+ activity deficits but failed to rescue altered network changes. Taken together, substantial neuronal and network dysfunction occurred in the early stage of tauopathy that was partially alleviated with acute tau antibody treatment, which highlights the importance of functional assessment when evaluating the therapeutic potential of tau antibodies. Highlights Layer 2/3 motor cortical neurons exhibited hypofunction in awake and behaving mice at the early stage of tauopathy.Altered neuronal network activity disrupted local circuitry engagement in tauopathy mice during treadmill running.Layer 2/3 motor cortical neurons in tauopathy mice exhibited enhanced neuronal excitability and altered excitatory synaptic transmissions.Acute tau antibody treatment reduced pathological tau and gliosis, and partially restored neuronal hypofunction profiles but not network dysfunction.
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Endepols H, Anglada-Huguet M, Mandelkow E, Neumaier B, Mandelkow EM, Drzezga A. Fragmentation of functional resting state brain networks in a transgenic mouse model of tau pathology: A metabolic connectivity study using [ 18F]FDG-PET. Exp Neurol 2024; 372:114632. [PMID: 38052272 DOI: 10.1016/j.expneurol.2023.114632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2023] [Revised: 11/07/2023] [Accepted: 11/29/2023] [Indexed: 12/07/2023]
Abstract
In a previous study, regional reductions in cerebral glucose metabolism have been demonstrated in the tauopathy mouse model rTg4510 (Endepols et al., 2022). Notably, glucose hypometabolism was present in some brain regions without co-localized synaptic degeneration measured with [18F]UCB-H. We hypothesized that in those regions hypometabolism may reflect reduced functional connectivity rather than synaptic damage. To test this hypothesis, we performed seed-based metabolic connectivity analyses using [18F]FDG-PET data in this mouse model. Eight rTg4510 mice at the age of seven months and 8 non-transgenic littermates were injected intraperitoneally with 11.1 ± 0.8 MBq [18F]FDG and spent a 35-min uptake period awake in single cages. Subsequently, they were anesthetized and measured in a small animal PET scanner for 30 min. Three seed-based connectivity analyses were performed per group. Seeds were selected for apparent mismatch between [18F]FDG and [18F]UCB-H. A seed was placed either in the medial orbitofrontal cortex, dorsal hippocampus or dorsal thalamus, and correlated with all other voxels of the brain across animals. In the control group, the emerging correlative pattern was strongly overlapping for all three seed locations, indicating a uniform fronto-thalamo-hippocampal resting state network. In contrast, rTg4510 mice showed three distinct networks with minimal overlap. Frontal and thalamic networks were greatly diminished. The hippocampus, however, formed a new network with the whole parietal cortex. We conclude that resting-state functional networks are fragmented in the brain of rTg4510 mice. Thus, hypometabolism can be explained by reduced functional connectivity of brain areas devoid of tau-related pathology, such as the thalamus.
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Affiliation(s)
- Heike Endepols
- University of Cologne, Faculty of Medicine and University Hospital Cologne, Institute of Radiochemistry and Experimental Molecular Imaging, Cologne, Germany; Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Straße, Jülich 52428, Germany; University of Cologne, Faculty of Medicine and University Hospital Cologne, Department of Nuclear Medicine, Cologne, Germany
| | | | - Eckhard Mandelkow
- German Center for Neurodegenerative Diseases (DZNE), Bonn-Cologne, Germany; Department Neurodegenerative Diseases & Gerontopsychiatry, University Hospital Bonn, Germany
| | - Bernd Neumaier
- University of Cologne, Faculty of Medicine and University Hospital Cologne, Institute of Radiochemistry and Experimental Molecular Imaging, Cologne, Germany; Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Straße, Jülich 52428, Germany.
| | - Eva-Maria Mandelkow
- German Center for Neurodegenerative Diseases (DZNE), Bonn-Cologne, Germany; Department Neurodegenerative Diseases & Gerontopsychiatry, University Hospital Bonn, Germany
| | - Alexander Drzezga
- University of Cologne, Faculty of Medicine and University Hospital Cologne, Department of Nuclear Medicine, Cologne, Germany; German Center for Neurodegenerative Diseases (DZNE), Bonn-Cologne, Germany; Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Molecular Organization of the Brain (INM-2), Wilhelm-Johnen-Straße, Jülich 52428, Germany
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Pagani M, Gutierrez-Barragan D, de Guzman AE, Xu T, Gozzi A. Mapping and comparing fMRI connectivity networks across species. Commun Biol 2023; 6:1238. [PMID: 38062107 PMCID: PMC10703935 DOI: 10.1038/s42003-023-05629-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/22/2023] [Indexed: 12/18/2023] Open
Abstract
Technical advances in neuroimaging, notably in fMRI, have allowed distributed patterns of functional connectivity to be mapped in the human brain with increasing spatiotemporal resolution. Recent years have seen a growing interest in extending this approach to rodents and non-human primates to understand the mechanism of fMRI connectivity and complement human investigations of the functional connectome. Here, we discuss current challenges and opportunities of fMRI connectivity mapping across species. We underscore the critical importance of physiologically decoding neuroimaging measures of brain (dys)connectivity via multiscale mechanistic investigations in animals. We next highlight a set of general principles governing the organization of mammalian connectivity networks across species. These include the presence of evolutionarily conserved network systems, a dominant cortical axis of functional connectivity, and a common repertoire of topographically conserved fMRI spatiotemporal modes. We finally describe emerging approaches allowing comparisons and extrapolations of fMRI connectivity findings across species. As neuroscientists gain access to increasingly sophisticated perturbational, computational and recording tools, cross-species fMRI offers novel opportunities to investigate the large-scale organization of the mammalian brain in health and disease.
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Affiliation(s)
- Marco Pagani
- Functional Neuroimaging Laboratory, Center for Neuroscience and Cognitive Systems, Istituto Italiano di Tecnologia, Rovereto, Italy
- Autism Center, Child Mind Institute, New York, NY, USA
- IMT School for Advanced Studies, Lucca, Italy
| | - Daniel Gutierrez-Barragan
- Functional Neuroimaging Laboratory, Center for Neuroscience and Cognitive Systems, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - A Elizabeth de Guzman
- Functional Neuroimaging Laboratory, Center for Neuroscience and Cognitive Systems, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Ting Xu
- Center for the Integrative Developmental Neuroscience, Child Mind Institute, New York, NY, USA
| | - Alessandro Gozzi
- Functional Neuroimaging Laboratory, Center for Neuroscience and Cognitive Systems, Istituto Italiano di Tecnologia, Rovereto, Italy.
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Mate de Gerando A, Quittot N, Frosch MP, Hyman BT. Reply: Soluble oligomers or insoluble fibrils? Acta Neuropathol 2023; 146:863-866. [PMID: 37733036 PMCID: PMC10628010 DOI: 10.1007/s00401-023-02634-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 09/22/2023]
Affiliation(s)
- Anastasie Mate de Gerando
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Cambridge, MA, USA
| | - Noe Quittot
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Cambridge, MA, USA
| | - Matthew P Frosch
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA
- Harvard Medical School, Cambridge, MA, USA
| | - Bradley T Hyman
- Department of Neurology, Massachusetts General Hospital, Boston, MA, USA.
- Harvard Medical School, Cambridge, MA, USA.
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Mahani FSN, Kalantari A, Fink GR, Hoehn M, Aswendt M. A systematic review of the relationship between magnetic resonance imaging based resting-state and structural networks in the rodent brain. Front Neurosci 2023; 17:1194630. [PMID: 37554291 PMCID: PMC10405456 DOI: 10.3389/fnins.2023.1194630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 07/05/2023] [Indexed: 08/10/2023] Open
Abstract
Recent developments in rodent brain imaging have enabled translational characterization of functional and structural connectivity at the whole brain level in vivo. Nevertheless, fundamental questions about the link between structural and functional networks remain unsolved. In this review, we systematically searched for experimental studies in rodents investigating both structural and functional network measures, including studies correlating functional connectivity using resting-state functional MRI with diffusion tensor imaging or viral tracing data. We aimed to answer whether functional networks reflect the architecture of the structural connectome, how this reciprocal relationship changes throughout a disease, how structural and functional changes relate to each other, and whether changes follow the same timeline. We present the knowledge derived exclusively from studies that included in vivo imaging of functional and structural networks. The limited number of available reports makes it difficult to draw general conclusions besides finding a spatial and temporal decoupling between structural and functional networks during brain disease. Data suggest that when overcoming the currently limited evidence through future studies with combined imaging in various disease models, it will be possible to explore the interaction between both network systems as a disease or recovery biomarker.
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Affiliation(s)
- Fatemeh S. N. Mahani
- Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany
- Department of Neurology, Faculty of Medicine and University Hospital, University of Cologne, Cologne, Germany
| | - Aref Kalantari
- Department of Neurology, Faculty of Medicine and University Hospital, University of Cologne, Cologne, Germany
| | - Gereon R. Fink
- Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany
- Department of Neurology, Faculty of Medicine and University Hospital, University of Cologne, Cologne, Germany
| | - Mathias Hoehn
- Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany
| | - Markus Aswendt
- Cognitive Neuroscience, Institute of Neuroscience and Medicine (INM-3), Research Centre Juelich, Juelich, Germany
- Department of Neurology, Faculty of Medicine and University Hospital, University of Cologne, Cologne, Germany
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Meftah S, Gan J. Alzheimer’s disease as a synaptopathy: Evidence for dysfunction of synapses during disease progression. Front Synaptic Neurosci 2023; 15:1129036. [PMID: 36970154 PMCID: PMC10033629 DOI: 10.3389/fnsyn.2023.1129036] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 02/23/2023] [Indexed: 03/11/2023] Open
Abstract
The synapse has consistently been considered a vulnerable and critical target within Alzheimer’s disease, and synapse loss is, to date, one of the main biological correlates of cognitive decline within Alzheimer’s disease. This occurs prior to neuronal loss with ample evidence that synaptic dysfunction precedes this, in support of the idea that synaptic failure is a crucial stage within disease pathogenesis. The two main pathological hallmarks of Alzheimer’s disease, abnormal aggregates of amyloid or tau proteins, have had demonstrable effects on synaptic physiology in animal and cellular models of Alzheimer’s disease. There is also growing evidence that these two proteins may have a synergistic effect on neurophysiological dysfunction. Here, we review some of the main findings of synaptic alterations in Alzheimer’s disease, and what we know from Alzheimer’s disease animal and cellular models. First, we briefly summarize some of the human evidence to suggest that synapses are altered, including how this relates to network activity. Subsequently, animal and cellular models of Alzheimer’s disease are considered, highlighting mouse models of amyloid and tau pathology and the role these proteins may play in synaptic dysfunction, either in isolation or examining how the two pathologies may interact in dysfunction. This specifically focuses on neurophysiological function and dysfunction observed within these animal models, typically measured using electrophysiology or calcium imaging. Following synaptic dysfunction and loss, it would be impossible to imagine that this would not alter oscillatory activity within the brain. Therefore, this review also discusses how this may underpin some of the aberrant oscillatory patterns seen in animal models of Alzheimer’s disease and human patients. Finally, an overview of some key directions and considerations in the field of synaptic dysfunction in Alzheimer’s disease is covered. This includes current therapeutics that are targeted specifically at synaptic dysfunction, but also methods that modulate activity to rescue aberrant oscillatory patterns. Other important future avenues of note in this field include the role of non-neuronal cell types such as astrocytes and microglia, and mechanisms of dysfunction independent of amyloid and tau in Alzheimer’s disease. The synapse will certainly continue to be an important target within Alzheimer’s disease for the foreseeable future.
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Affiliation(s)
- Soraya Meftah
- UK Dementia Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
| | - Jian Gan
- UK Dementia Research Institute, The University of Edinburgh, Edinburgh, United Kingdom
- Centre for Discovery Brain Sciences, The University of Edinburgh, Edinburgh, United Kingdom
- *Correspondence: Jian Gan,
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Samudra N, Ranasinghe K, Kirsch H, Rankin K, Miller B. Etiology and Clinical Significance of Network Hyperexcitability in Alzheimer's Disease: Unanswered Questions and Next Steps. J Alzheimers Dis 2023; 92:13-27. [PMID: 36710680 DOI: 10.3233/jad-220983] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cortical network hyperexcitability related to synaptic dysfunction in Alzheimer's disease (AD) is a potential target for therapeutic intervention. In recent years, there has been increased interest in the prevalence of silent seizures and interictal epileptiform discharges (IEDs, or seizure tendency), with both entities collectively termed "subclinical epileptiform activity" (SEA), on neurophysiologic studies in AD patients. SEA has been demonstrated to be common in AD, with prevalence estimates ranging between 22-54%. Converging lines of basic and clinical evidence imply that modifying a hyperexcitable state results in an improvement in cognition. In particular, though these results require further confirmation, post-hoc findings from a recent phase II clinical trial suggest a therapeutic effect with levetiracetam administration in patients with AD and IEDs. Here, we review key unanswered questions as well as potential clinical trial avenues. Specifically, we discuss postulated mechanisms and treatment of hyperexcitability in patients with AD, which are of interest in designing future disease-modifying therapies. Criteria to prompt screening and optimal screening methodology for hyperexcitability have yet to be defined, as does timing and personalization of therapeutic intervention.
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Affiliation(s)
- Niyatee Samudra
- Memory and Aging Center, University of California, San Francisco, San Francisco, CA, USA
| | - Kamalini Ranasinghe
- Memory and Aging Center, University of California, San Francisco, San Francisco, CA, USA
| | - Heidi Kirsch
- University of California, San Francisco Comprehensive Epilepsy Center, San Francisco, CA, USA
| | - Katherine Rankin
- Memory and Aging Center, University of California, San Francisco, San Francisco, CA, USA
| | - Bruce Miller
- Memory and Aging Center, University of California, San Francisco, San Francisco, CA, USA
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Rodrigues FR, Papanikolaou A, Holeniewska J, Phillips KG, Saleem AB, Solomon SG. Altered low-frequency brain rhythms precede changes in gamma power during tauopathy. iScience 2022; 25:105232. [PMID: 36274955 PMCID: PMC9579020 DOI: 10.1016/j.isci.2022.105232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 08/22/2022] [Accepted: 09/25/2022] [Indexed: 11/12/2022] Open
Abstract
Neurodegenerative disorders are associated with widespread disruption to brain activity and brain rhythms. Some disorders are linked to dysfunction of the membrane-associated protein Tau. Here, we ask how brain rhythms are affected in rTg4510 mouse model of tauopathy, at an early stage of tauopathy (5 months), and at a more advanced stage (8 months). We measured brain rhythms in primary visual cortex in presence or absence of visual stimulation, while monitoring pupil diameter and locomotion to establish behavioral state. At 5 months, we found increased low-frequency rhythms during resting state in tauopathic animals, associated with periods of abnormally increased neural synchronization. At 8 months, this increase in low-frequency rhythms was accompanied by a reduction of power in the gamma range. Our results therefore show that slower rhythms are impaired earlier than gamma rhythms in this model of tauopathy, and suggest that electrophysiological measurements can track the progression of tauopathic neurodegeneration.
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Affiliation(s)
- Fabio R. Rodrigues
- UCL Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, London WC1H 0AP, UK
| | - Amalia Papanikolaou
- UCL Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, London WC1H 0AP, UK
| | - Joanna Holeniewska
- UCL Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, London WC1H 0AP, UK
| | | | - Aman B. Saleem
- UCL Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, London WC1H 0AP, UK
| | - Samuel G. Solomon
- UCL Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, London WC1H 0AP, UK
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Vinh To X, Soni N, Medeiros R, Alateeq K, Nasrallah FA. Traumatic brain injury alterations in the functional connectome are associated with neuroinflammation but not tau in a P30IL tauopathy mouse model. Brain Res 2022; 1789:147955. [PMID: 35636493 DOI: 10.1016/j.brainres.2022.147955] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 04/19/2022] [Accepted: 05/25/2022] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Traumatic Brain Injury (TBI) is often associated with long-term cognitive deficits and altered brain networks which have been linked with accumulation of neurofibrillary tau tangles and neuroinflammation. In this work, we investigated the changes in the brain post-TBI in an Alzheimer's disease pR5 tauopathy model and evaluated the contribution of tauopathy and neuroinflammation to connectivity alterations using resting-state functional Magnetic Resonance Imaging (rs-fMRI). METHOD 26 P301L tau transgenic mice of 8-9 months of age (21-35 g) expressing the human tau isoform carrying the pathogenic P301L mutation were used for the study. Animals were assessed at day 1 and 7 post-injury/craniotomy and were randomly divided into four groups. All animals underwent an MRI scan on a 9.4 T Bruker system where rsfMRI was acquired. Following imaging, brains were stained with pSer (396 + 404), glial fibrillary acidic protein (GFAP), and ionised calcium-binding adaptor molecule-1 (Iba-1). Group-information-guided Independent Component Analysis (GIG-ICA) and region-of-interest (ROI)-based network connectivity approaches were applied. Principal Component Regression was applied to predict connectivity network strength from the corresponding ROIs. RESULTS TBI mice showed decreased functional connectivity in the dentate gyrus, thalamus, and other areas compared to sham animals at day 1 post-injury with the majority of changes resolving at day 7. Principal Component Regression showed only the contralateral CA1 network strength was correlated with the CA1's astrocyte and microglia cell density and the ipsilateral thalamus network strength was correlated with the ipsilateral thalamus' astrocyte and microglia cell density. CONCLUSION We present the first report on the temporal alterations in functional connectivity in a P30IL mouse model following TBI. Connectivity between key regions known to be affected in Alzheimer's disease were short-term and reversible following injury. Connectivity strength in CA1 and thalamus showed significant correlation with astrocyte and microglial cell density but not tau density.
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Affiliation(s)
- Xuan Vinh To
- The Queensland Brain Institute, The University of Queensland, St. Lucia, QLD, Australia
| | - Neha Soni
- The Queensland Brain Institute, The University of Queensland, St. Lucia, QLD, Australia
| | - Rodrigo Medeiros
- The Queensland Brain Institute, The University of Queensland, St. Lucia, QLD, Australia
| | - Khawlah Alateeq
- The Queensland Brain Institute, The University of Queensland, St. Lucia, QLD, Australia
| | - Fatima A Nasrallah
- The Queensland Brain Institute, The University of Queensland, St. Lucia, QLD, Australia; The University of California, Irvine, The United States of America.
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Assessment of the In Vivo Relationship Between Cerebral Hypometabolism, Tau Deposition, TSPO Expression, and Synaptic Density in a Tauopathy Mouse Model: a Multi-tracer PET Study. Mol Neurobiol 2022; 59:3402-3413. [PMID: 35312967 PMCID: PMC9148291 DOI: 10.1007/s12035-022-02793-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 03/05/2022] [Indexed: 11/03/2022]
Abstract
Cerebral glucose hypometabolism is a typical hallmark of Alzheimer’s disease (AD), usually associated with ongoing neurodegeneration and neuronal dysfunction. However, underlying pathological processes are not fully understood and reproducibility in animal models is not well established. The aim of the present study was to investigate the regional interrelation of glucose hypometabolism measured by [18F]FDG positron emission tomography (PET) with various molecular targets of AD pathophysiology using the PET tracers [18F]PI-2620 for tau deposition, [18F]DPA-714 for TSPO expression associated with neuroinflammation, and [18F]UCB-H for synaptic density in a transgenic tauopathy mouse model. Seven-month-old rTg4510 mice (n = 8) and non-transgenic littermates (n = 8) were examined in a small animal PET scanner with the tracers listed above. Hypometabolism was observed throughout the forebrain of rTg4510 mice. Tau pathology, increased TSPO expression, and synaptic loss were co-localized in the cortex and hippocampus and correlated with hypometabolism. In the thalamus, however, hypometabolism occurred in the absence of tau-related pathology. Thus, cerebral hypometabolism was associated with two regionally distinct forms of molecular pathology: (1) characteristic neuropathology of the Alzheimer-type including synaptic degeneration and neuroinflammation co-localized with tau deposition in the cerebral cortex, and (2) pathological changes in the thalamus in the absence of other markers of AD pathophysiology, possibly reflecting downstream or remote adaptive processes which may affect functional connectivity. Our study demonstrates the feasibility of a multitracer approach to explore complex interactions of distinct AD-pathomechanisms in vivo in a small animal model. The observations demonstrate that multiple, spatially heterogeneous pathomechanisms can contribute to hypometabolism observed in AD mouse models and they motivate future longitudinal studies as well as the investigation of possibly comparable pathomechanisms in human patients.
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Xu N, LaGrow TJ, Anumba N, Lee A, Zhang X, Yousefi B, Bassil Y, Clavijo GP, Khalilzad Sharghi V, Maltbie E, Meyer-Baese L, Nezafati M, Pan WJ, Keilholz S. Functional Connectivity of the Brain Across Rodents and Humans. Front Neurosci 2022; 16:816331. [PMID: 35350561 PMCID: PMC8957796 DOI: 10.3389/fnins.2022.816331] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Accepted: 02/14/2022] [Indexed: 12/15/2022] Open
Abstract
Resting-state functional magnetic resonance imaging (rs-fMRI), which measures the spontaneous fluctuations in the blood oxygen level-dependent (BOLD) signal, is increasingly utilized for the investigation of the brain's physiological and pathological functional activity. Rodents, as a typical animal model in neuroscience, play an important role in the studies that examine the neuronal processes that underpin the spontaneous fluctuations in the BOLD signal and the functional connectivity that results. Translating this knowledge from rodents to humans requires a basic knowledge of the similarities and differences across species in terms of both the BOLD signal fluctuations and the resulting functional connectivity. This review begins by examining similarities and differences in anatomical features, acquisition parameters, and preprocessing techniques, as factors that contribute to functional connectivity. Homologous functional networks are compared across species, and aspects of the BOLD fluctuations such as the topography of the global signal and the relationship between structural and functional connectivity are examined. Time-varying features of functional connectivity, obtained by sliding windowed approaches, quasi-periodic patterns, and coactivation patterns, are compared across species. Applications demonstrating the use of rs-fMRI as a translational tool for cross-species analysis are discussed, with an emphasis on neurological and psychiatric disorders. Finally, open questions are presented to encapsulate the future direction of the field.
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Affiliation(s)
- Nan Xu
- Biomedical Engineering, Emory University and Georgia Tech, Atlanta, GA, United States
| | - Theodore J. LaGrow
- Electrical and Computer Engineering, Georgia Tech, Atlanta, GA, United States
| | - Nmachi Anumba
- Biomedical Engineering, Emory University and Georgia Tech, Atlanta, GA, United States
| | - Azalea Lee
- Neuroscience Graduate Program, Emory University, Atlanta, GA, United States
- Emory University School of Medicine, Atlanta, GA, United States
| | - Xiaodi Zhang
- Biomedical Engineering, Emory University and Georgia Tech, Atlanta, GA, United States
| | - Behnaz Yousefi
- Biomedical Engineering, Emory University and Georgia Tech, Atlanta, GA, United States
| | - Yasmine Bassil
- Neuroscience Graduate Program, Emory University, Atlanta, GA, United States
| | - Gloria P. Clavijo
- Biomedical Engineering, Emory University and Georgia Tech, Atlanta, GA, United States
| | | | - Eric Maltbie
- Biomedical Engineering, Emory University and Georgia Tech, Atlanta, GA, United States
| | - Lisa Meyer-Baese
- Biomedical Engineering, Emory University and Georgia Tech, Atlanta, GA, United States
| | - Maysam Nezafati
- Biomedical Engineering, Emory University and Georgia Tech, Atlanta, GA, United States
| | - Wen-Ju Pan
- Biomedical Engineering, Emory University and Georgia Tech, Atlanta, GA, United States
| | - Shella Keilholz
- Biomedical Engineering, Emory University and Georgia Tech, Atlanta, GA, United States
- Neuroscience Graduate Program, Emory University, Atlanta, GA, United States
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Stancu IC, Lodder C, Botella Lucena P, Vanherle S, Gutiérrez de Ravé M, Terwel D, Bottelbergs A, Dewachter I. The NLRP3 inflammasome modulates tau pathology and neurodegeneration in a tauopathy model. Glia 2022; 70:1117-1132. [PMID: 35174546 PMCID: PMC9307007 DOI: 10.1002/glia.24160] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 02/02/2022] [Accepted: 02/03/2022] [Indexed: 12/28/2022]
Abstract
An active role of neuroinflammation and the NLRP3 inflammasome in Alzheimer's disease and related tauopathies is increasingly identified, supporting NLRP3 as an interesting therapeutic target. However, its effect on tau‐associated neurodegeneration, a key‐process in tauopathies, remains unknown. While tau pathology and neurodegeneration are closely correlated, different tau forms may act as culprits in both characteristics and NLRP3‐dependent microglial processes may differently affect both processes, indicating the need to study the role of NLRP3 in both processes concomitantly. To study the role of NLRP3 on tau pathology, prion‐like propagation and tau‐associated neurodegeneration we generated crosses of NLRP3 deficient mice with tauP301S (PS19) transgenic mice. In this model we studied non‐seeded tau pathology and hippocampal atrophy, reminiscent characteristics of tauopathies. Tau pathology in hippocampus and cortex was significantly decreased in tau.NLRP3−/− versus tau.NLRP3+/+ mice. Importantly, tau.NLRP3−/− mice also displayed significantly decreased hippocampal atrophy, indicating a role of NLRP3 in neurodegeneration. We furthermore assessed the effect of NLRP3 deficiency on tau propagation and associated hippocampal atrophy. NLRP3 deficiency significantly decreased prion‐like seeding and propagation of tau pathology, reflected in decreased tau pathology in ipsi‐ and contralateral hippocampus and cortex in tau.NLRP3−/− following tau seeding. Most importantly, hippocampal atrophy was significantly less in tau‐seeded tau.NLRP3−/− mice at 8 months. We here demonstrate for the first time that NLRP3 activation affects tau‐associated neurodegeneration and seeded and non‐seeded tau pathology, hence affecting key molecular processes in tauopathies. Our data thereby provide key‐information in the validation of NLRP3 inflammasome as therapeutic target for AD and related tauopathies.
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Affiliation(s)
- Ilie Cosmin Stancu
- Department of Neurosciences, Biomedical Research Institute, Hasselt University, Hasselt, Belgium
| | - Chritica Lodder
- Department of Neurosciences, Biomedical Research Institute, Hasselt University, Hasselt, Belgium
| | - Pablo Botella Lucena
- Department of Neurosciences, Biomedical Research Institute, Hasselt University, Hasselt, Belgium
| | - Sarah Vanherle
- Department of Neurosciences, Biomedical Research Institute, Hasselt University, Hasselt, Belgium
| | - Manuel Gutiérrez de Ravé
- Department of Neurosciences, Biomedical Research Institute, Hasselt University, Hasselt, Belgium
| | - Dick Terwel
- Department of Neurosciences, Biomedical Research Institute, Hasselt University, Hasselt, Belgium
| | - Astrid Bottelbergs
- Neuroscience Department, Janssen Research and Development, A Division of Janssen Pharmaceutica NV, Beerse, Belgium
| | - Ilse Dewachter
- Department of Neurosciences, Biomedical Research Institute, Hasselt University, Hasselt, Belgium
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13
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Hall GR, Boehm-Sturm P, Dirnagl U, Finke C, Foddis M, Harms C, Koch SP, Kuchling J, Madan CR, Mueller S, Sassi C, Sotiropoulos SN, Trueman RC, Wallis MD, Yildirim F, Farr TD. Long-Term Connectome Analysis Reveals Reshaping of Visual, Spatial Networks in a Model With Vascular Dementia Features. Stroke 2022; 53:1735-1745. [PMID: 35105183 PMCID: PMC9022688 DOI: 10.1161/strokeaha.121.036997] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
Connectome analysis of neuroimaging data is a rapidly expanding field that offers the potential to diagnose, characterize, and predict neurological disease. Animal models provide insight into biological mechanisms that underpin disease, but connectivity approaches are currently lagging in the rodent.
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Affiliation(s)
- Gerard R Hall
- School of Life Sciences, University of Nottingham, United Kingdom (G.R.H., R.C.T., M.D.W., T.D.F.)
| | - Philipp Boehm-Sturm
- Department of Experimental Neurology, Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., T.D.F.).,corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Germany. NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRIs, Charité-Universitätsmedizin Berlin, Germany. (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., F.Y., T.D.F.)
| | - Ulrich Dirnagl
- Department of Experimental Neurology, Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., T.D.F.).,corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Germany. NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRIs, Charité-Universitätsmedizin Berlin, Germany. (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., F.Y., T.D.F.).,German Center for Neurodegenerative Diseases, Berlin Site, Germany (U.D.)
| | - Carsten Finke
- Department of Neurology, Charité-Universitätsmedizin Berlin, Germany. (C.F., J.K.).,Berlin School of Mind and Brain, Humboldt Universität zu Berlin, Germany (C.F.)
| | - Marco Foddis
- Department of Experimental Neurology, Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., T.D.F.).,corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Germany. NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRIs, Charité-Universitätsmedizin Berlin, Germany. (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., F.Y., T.D.F.)
| | - Christoph Harms
- Department of Experimental Neurology, Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., T.D.F.).,corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Germany. NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRIs, Charité-Universitätsmedizin Berlin, Germany. (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., F.Y., T.D.F.)
| | - Stefan Paul Koch
- Department of Experimental Neurology, Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., T.D.F.).,corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Germany. NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRIs, Charité-Universitätsmedizin Berlin, Germany. (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., F.Y., T.D.F.)
| | - Joseph Kuchling
- Experimental and Clinical Research Center, Max Delbrueck Center for Molecular Medicine and Charité-Universitätsmedizin Berlin (J.K.).,Department of Neurology, Charité-Universitätsmedizin Berlin, Germany. (C.F., J.K.)
| | | | - Susanne Mueller
- Department of Experimental Neurology, Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., T.D.F.).,corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Germany. NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRIs, Charité-Universitätsmedizin Berlin, Germany. (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., F.Y., T.D.F.)
| | - Celeste Sassi
- Department of Experimental Neurology, Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., T.D.F.).,corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Germany. NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRIs, Charité-Universitätsmedizin Berlin, Germany. (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., F.Y., T.D.F.)
| | - Stamatios N Sotiropoulos
- Sir Peter Mansfield Imaging Centre, School of Medicine, University of Nottingham, United Kingdom (S.N.S.).,Centre for Functional MRI of the Brain, University of Oxford, United Kingdom (S.N.S.)
| | - Rebecca C Trueman
- School of Life Sciences, University of Nottingham, United Kingdom (G.R.H., R.C.T., M.D.W., T.D.F.)
| | - Marcus D Wallis
- School of Life Sciences, University of Nottingham, United Kingdom (G.R.H., R.C.T., M.D.W., T.D.F.)
| | - Ferah Yildirim
- corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Germany. NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRIs, Charité-Universitätsmedizin Berlin, Germany. (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., F.Y., T.D.F.).,NeuroCure Cluster of Excellence and Department of Psychiatry and Psychotherapy, Charité-Universitätsmedizin Berlin, Germany. (F.Y.)
| | - Tracy D Farr
- School of Life Sciences, University of Nottingham, United Kingdom (G.R.H., R.C.T., M.D.W., T.D.F.).,Department of Experimental Neurology, Center for Stroke Research Berlin, Charité-Universitätsmedizin Berlin (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., T.D.F.).,corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin and Berlin Institute of Health, Germany. NeuroCure Cluster of Excellence and Charité Core Facility 7T Experimental MRIs, Charité-Universitätsmedizin Berlin, Germany. (P.B.-S., U.D., M.F., C.H., S.P.K., S.M., C.S., F.Y., T.D.F.)
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14
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Ni R. Magnetic Resonance Imaging in Tauopathy Animal Models. Front Aging Neurosci 2022; 13:791679. [PMID: 35145392 PMCID: PMC8821905 DOI: 10.3389/fnagi.2021.791679] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 12/27/2021] [Indexed: 11/13/2022] Open
Abstract
The microtubule-associated protein tau plays an important role in tauopathic diseases such as Alzheimer’s disease and primary tauopathies such as progressive supranuclear palsy and corticobasal degeneration. Tauopathy animal models, such as transgenic, knock-in mouse and rat models, recapitulating tauopathy have facilitated the understanding of disease mechanisms. Aberrant accumulation of hyperphosphorylated tau contributes to synaptic deficits, neuroinflammation, and neurodegeneration, leading to cognitive impairment in animal models. Recent advances in molecular imaging using positron emission tomography (PET) and magnetic resonance imaging (MRI) have provided valuable insights into the time course of disease pathophysiology in tauopathy animal models. High-field MRI has been applied for in vivo imaging in animal models of tauopathy, including diffusion tensor imaging for white matter integrity, arterial spin labeling for cerebral blood flow, resting-state functional MRI for functional connectivity, volumetric MRI for neurodegeneration, and MR spectroscopy. In addition, MR contrast agents for non-invasive imaging of tau have been developed recently. Many preclinical MRI indicators offer excellent translational value and provide a blueprint for clinical MRI in the brains of patients with tauopathies. In this review, we summarized the recent advances in using MRI to visualize the pathophysiology of tauopathy in small animals. We discussed the outstanding challenges in brain imaging using MRI in small animals and propose a future outlook for visualizing tau-related alterations in the brains of animal models.
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Affiliation(s)
- Ruiqing Ni
- Institute for Biomedical Engineering, ETH Zurich and University of Zurich, Zurich, Switzerland
- Institute for Regenerative Medicine, University of Zurich, Zurich, Switzerland
- *Correspondence: Ruiqing Ni,
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15
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Van der Linden A, Hoehn M. Monitoring Neuronal Network Disturbances of Brain Diseases: A Preclinical MRI Approach in the Rodent Brain. Front Cell Neurosci 2022; 15:815552. [PMID: 35046778 PMCID: PMC8761853 DOI: 10.3389/fncel.2021.815552] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 12/06/2021] [Indexed: 12/20/2022] Open
Abstract
Functional and structural neuronal networks, as recorded by resting-state functional MRI and diffusion MRI-based tractography, gain increasing attention as data driven whole brain imaging methods not limited to the foci of the primary pathology or the known key affected regions but permitting to characterize the entire network response of the brain after disease or injury. Their connectome contents thus provide information on distal brain areas, directly or indirectly affected by and interacting with the primary pathological event or affected regions. From such information, a better understanding of the dynamics of disease progression is expected. Furthermore, observation of the brain's spontaneous or treatment-induced improvement will contribute to unravel the underlying mechanisms of plasticity and recovery across the whole-brain networks. In the present review, we discuss the values of functional and structural network information derived from systematic and controlled experimentation using clinically relevant animal models. We focus on rodent models of the cerebral diseases with high impact on social burdens, namely, neurodegeneration, and stroke.
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Affiliation(s)
- Annemie Van der Linden
- Bio-Imaging Lab, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
- μNEURO Research Centre of Excellence, University of Antwerp, Antwerp, Belgium
| | - Mathias Hoehn
- Research Center Jülich, Institute 3 for Neuroscience and Medicine, Jülich, Germany
- *Correspondence: Mathias Hoehn
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16
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Abstract
Alzheimer's disease (AD) is characterized by the presence of amyloid beta (Aβ) plaques and neurofibrillary tangles (NFTs), neuronal and synaptic loss and inflammation of the central nervous system (CNS). The majority of AD research has been dedicated to the understanding of two major AD hallmarks (i.e. Aβ and NFTs); however, recent genome-wide association studies (GWAS) data indicate neuroinflammation as having a critical role in late-onset AD (LOAD) development, thus unveiling a novel avenue for AD therapeutics. Recent evidence has provided much support to the innate immune system's involvement with AD progression; however, much remains to be uncovered regarding the role of glial cells, specifically microglia, in AD. Moreover, numerous variants in immune and/or microglia-related genes have been identified in whole-genome sequencing and GWAS analyses, including such genes as TREM2, CD33, APOE, API1, MS4A, ABCA7, BIN1, CLU, CR1, INPP5D, PICALM and PLCG2. In this review, we aim to provide an insight into the function of the major LOAD-associated microglia response genes.
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Affiliation(s)
- Lauren A. Jonas
- Weill Cornell, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10065, USA,Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Tanya Jain
- Weill Cornell, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10065, USA,Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Yue-Ming Li
- Weill Cornell, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10065, USA,Chemical Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
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17
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Aswendt M, Green C, Sadler R, Llovera G, Dzikowski L, Heindl S, Gomez de Agüero M, Diedenhofen M, Vogel S, Wieters F, Wiedermann D, Liesz A, Hoehn M. The gut microbiota modulates brain network connectivity under physiological conditions and after acute brain ischemia. iScience 2021; 24:103095. [PMID: 34622150 PMCID: PMC8479691 DOI: 10.1016/j.isci.2021.103095] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 07/14/2021] [Accepted: 09/02/2021] [Indexed: 12/13/2022] Open
Abstract
The gut microbiome has been implicated as a key regulator of brain function in health and disease. But the impact of gut microbiota on functional brain connectivity is unknown. We used resting-state functional magnetic resonance imaging in germ-free and normally colonized mice under naive conditions and after ischemic stroke. We observed a strong, brain-wide increase of functional connectivity in germ-free animals. Graph theoretical analysis revealed significant higher values in germ-free animals, indicating a stronger and denser global network but with less structural organization. Breakdown of network function after stroke equally affected germ-free and colonized mice. Results from histological analyses showed changes in dendritic spine densities, as well as an immature microglial phenotype, indicating impaired microglia-neuron interaction in germ-free mice as potential cause of this phenomenon. These results demonstrate the substantial impact of bacterial colonization on brain-wide function and extend our so far mainly (sub) cellular understanding of the gut-brain axis.
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Affiliation(s)
- Markus Aswendt
- Department of Neurology, University of Cologne, Faculty of Medicine and University Hospital, 50923 Cologne, Germany
| | - Claudia Green
- In-vivo-NMR Laboratory, Max Planck Institute for Metabolism Research, Gleuelerstrasse 50, 50931 Cologne, Germany
| | - Rebecca Sadler
- Institute for Stroke and Dementia Research (ISD), LMU Munich, Feodor-Lynen Strasse 17, 81377 Munich, Germany
| | - Gemma Llovera
- Institute for Stroke and Dementia Research (ISD), LMU Munich, Feodor-Lynen Strasse 17, 81377 Munich, Germany
| | - Lauren Dzikowski
- Institute for Stroke and Dementia Research (ISD), LMU Munich, Feodor-Lynen Strasse 17, 81377 Munich, Germany
| | - Steffanie Heindl
- Institute for Stroke and Dementia Research (ISD), LMU Munich, Feodor-Lynen Strasse 17, 81377 Munich, Germany
| | - Mercedes Gomez de Agüero
- Department for BioMedical Research (DBMR), University of Bern, 3012 Bern, Switzerland
- Institute of Systems Immunology, Julius-Maximilians University of Würzburg, 97070 Würzburg, Germany
| | - Michael Diedenhofen
- In-vivo-NMR Laboratory, Max Planck Institute for Metabolism Research, Gleuelerstrasse 50, 50931 Cologne, Germany
| | - Stefanie Vogel
- In-vivo-NMR Laboratory, Max Planck Institute for Metabolism Research, Gleuelerstrasse 50, 50931 Cologne, Germany
| | - Frederique Wieters
- Department of Neurology, University of Cologne, Faculty of Medicine and University Hospital, 50923 Cologne, Germany
| | - Dirk Wiedermann
- In-vivo-NMR Laboratory, Max Planck Institute for Metabolism Research, Gleuelerstrasse 50, 50931 Cologne, Germany
| | - Arthur Liesz
- Institute for Stroke and Dementia Research (ISD), LMU Munich, Feodor-Lynen Strasse 17, 81377 Munich, Germany
- Munich Cluster for Systems Neurology (SyNergy), 80807 Munich, Germany
| | - Mathias Hoehn
- In-vivo-NMR Laboratory, Max Planck Institute for Metabolism Research, Gleuelerstrasse 50, 50931 Cologne, Germany
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18
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Toniolo S, Sen A, Husain M. Modulation of Brain Hyperexcitability: Potential New Therapeutic Approaches in Alzheimer's Disease. Int J Mol Sci 2020; 21:E9318. [PMID: 33297460 PMCID: PMC7730926 DOI: 10.3390/ijms21239318] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 11/30/2020] [Accepted: 12/05/2020] [Indexed: 12/12/2022] Open
Abstract
People with Alzheimer's disease (AD) have significantly higher rates of subclinical and overt epileptiform activity. In animal models, oligomeric Aβ amyloid is able to induce neuronal hyperexcitability even in the early phases of the disease. Such aberrant activity subsequently leads to downstream accumulation of toxic proteins, and ultimately to further neurodegeneration and neuronal silencing mediated by concomitant tau accumulation. Several neurotransmitters participate in the initial hyperexcitable state, with increased synaptic glutamatergic tone and decreased GABAergic inhibition. These changes appear to activate excitotoxic pathways and, ultimately, cause reduced long-term potentiation, increased long-term depression, and increased GABAergic inhibitory remodelling at the network level. Brain hyperexcitability has therefore been identified as a potential target for therapeutic interventions aimed at enhancing cognition, and, possibly, disease modification in the longer term. Clinical trials are ongoing to evaluate the potential efficacy in targeting hyperexcitability in AD, with levetiracetam showing some encouraging effects. Newer compounds and techniques, such as gene editing via viral vectors or brain stimulation, also show promise. Diagnostic challenges include identifying best biomarkers for measuring sub-clinical epileptiform discharges. Determining the timing of any intervention is critical and future trials will need to carefully stratify participants with respect to the phase of disease pathology.
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Affiliation(s)
- Sofia Toniolo
- Cognitive Neurology Group, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK;
- Wellcome Trust Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, Oxford OX2 6AE, UK
| | - Arjune Sen
- Oxford Epilepsy Research Group, Nuffield Department Clinical Neurosciences, John Radcliffe Hospital, Oxford OX3 9DU, UK;
| | - Masud Husain
- Cognitive Neurology Group, Nuffield Department of Clinical Neurosciences, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DU, UK;
- Wellcome Trust Centre for Integrative Neuroimaging, Department of Experimental Psychology, University of Oxford, Oxford OX2 6AE, UK
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19
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Koller EJ, Chakrabarty P. Tau-Mediated Dysregulation of Neuroplasticity and Glial Plasticity. Front Mol Neurosci 2020; 13:151. [PMID: 32973446 PMCID: PMC7472665 DOI: 10.3389/fnmol.2020.00151] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/20/2020] [Indexed: 01/14/2023] Open
Abstract
The inability of individual neurons to compensate for aging-related damage leads to a gradual loss of functional plasticity in the brain accompanied by progressive impairment in learning and memory. Whereas this loss in neuroplasticity is gradual during normal aging, in neurodegenerative diseases such as Alzheimer’s disease (AD), this loss is accelerated dramatically, leading to the incapacitation of patients within a decade of onset of cognitive symptoms. The mechanisms that underlie this accelerated loss of neuroplasticity in AD are still not completely understood. While the progressively increasing proteinopathy burden, such as amyloid β (Aβ) plaques and tau tangles, definitely contribute directly to a neuron’s functional demise, the role of non-neuronal cells in controlling neuroplasticity is slowly being recognized as another major factor. These non-neuronal cells include astrocytes, microglia, and oligodendrocytes, which through regulating brain homeostasis, structural stability, and trophic support, play a key role in maintaining normal functioning and resilience of the neuronal network. It is believed that chronic signaling from these cells affects the homeostatic network of neuronal and non-neuronal cells to an extent to destabilize this harmonious milieu in neurodegenerative diseases like AD. Here, we will examine the experimental evidence regarding the direct and indirect pathways through which astrocytes and microglia can alter brain plasticity in AD, specifically as they relate to the development and progression of tauopathy. In this review article, we describe the concepts of neuroplasticity and glial plasticity in healthy aging, delineate possible mechanisms underlying tau-induced plasticity dysfunction, and discuss current clinical trials as well as future disease-modifying approaches.
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Affiliation(s)
- Emily J Koller
- Department of Neuroscience, University of Florida, Gainesville, FL, United States.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, United States
| | - Paramita Chakrabarty
- Department of Neuroscience, University of Florida, Gainesville, FL, United States.,Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, United States.,McKnight Brain Institute, University of Florida, Gainesville, FL, United States
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20
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Busche MA, Hyman BT. Synergy between amyloid-β and tau in Alzheimer's disease. Nat Neurosci 2020; 23:1183-1193. [PMID: 32778792 DOI: 10.1038/s41593-020-0687-6] [Citation(s) in RCA: 523] [Impact Index Per Article: 130.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 07/06/2020] [Indexed: 12/24/2022]
Abstract
Patients with Alzheimer's disease (AD) present with both extracellular amyloid-β (Aβ) plaques and intracellular tau-containing neurofibrillary tangles in the brain. For many years, the prevailing view of AD pathogenesis has been that changes in Aβ precipitate the disease process and initiate a deleterious cascade involving tau pathology and neurodegeneration. Beyond this 'triggering' function, it has been typically presumed that Aβ and tau act independently and in the absence of specific interaction. However, accumulating evidence now suggests otherwise and contends that both pathologies have synergistic effects. This could not only help explain negative results from anti-Aβ clinical trials but also suggest that trials directed solely at tau may need to be reconsidered. Here, drawing from extensive human and disease model data, we highlight the latest evidence base pertaining to the complex Aβ-tau interaction and underscore its crucial importance to elucidating disease pathogenesis and the design of next-generation AD therapeutic trials.
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Affiliation(s)
- Marc Aurel Busche
- UK Dementia Research Institute at UCL, University College London, London, UK.
| | - Bradley T Hyman
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Boston, USA
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21
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Harris SS, Wolf F, De Strooper B, Busche MA. Tipping the Scales: Peptide-Dependent Dysregulation of Neural Circuit Dynamics in Alzheimer’s Disease. Neuron 2020; 107:417-435. [DOI: 10.1016/j.neuron.2020.06.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 04/24/2020] [Accepted: 06/01/2020] [Indexed: 02/07/2023]
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22
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Detrez JR, Ben-Nejma IRH, Van Kolen K, Van Dam D, De Deyn PP, Fransen E, Verhoye M, Timmermans JP, Nuydens R, Van der Linden A, Keliris GA, De Vos WH. Progressive tau aggregation does not alter functional brain network connectivity in seeded hTau.P301L mice. Neurobiol Dis 2020; 143:105011. [PMID: 32653674 DOI: 10.1016/j.nbd.2020.105011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Revised: 06/21/2020] [Accepted: 07/07/2020] [Indexed: 12/21/2022] Open
Abstract
Progressive accumulation of hyperphosphorylated tau is a hallmark of various neurodegenerative disorders including Alzheimer's disease. However, to date, the functional effects of tau pathology on brain network connectivity remain poorly understood. To directly interrogate the impact of tau pathology on functional brain connectivity, we conducted a longitudinal experiment in which we monitored a fibril-seeded hTau.P301L mouse model using correlative whole-brain microscopy and resting-state functional MRI. Despite a progressive aggravation of tau pathology across the brain, the major resting-state networks appeared unaffected up to 15 weeks after seeding. Targeted analyses also showed that the connectivity of regions with high levels of hyperphosphorylated tau was comparable to that observed in controls. In line with the ostensible retention of connectivity, no behavioural changes were detected between seeded and control hTau.P301L mice as determined by three different paradigms. Our data indicate that seeded tau pathology, with accumulation of tau aggregates throughout different regions of the brain, does not alter functional connectivity or behaviour in this mouse model. Additional correlative functional studies on different mouse models should help determine whether this is a generalizable trait of tauopathies.
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Affiliation(s)
- Jan R Detrez
- Laboratory of Cell Biology and Histology, University of Antwerp, Belgium
| | | | - Kristof Van Kolen
- Department of Neuroscience, Janssen Research and Development, Belgium.
| | - Debby Van Dam
- Laboratory of Neurochemistry and Behavior, University of Antwerp, Belgium; Department of Neurology and Alzheimer Center Groningen, University of Groningen and University Medical Center Groningen (UMCG), Groningen, The Netherlands.
| | - Peter Paul De Deyn
- Laboratory of Neurochemistry and Behavior, University of Antwerp, Belgium; Department of Neurology, Memory Clinic of Hospital Network Antwerp (ZNA) Middelheim and Hoge Beuken, Antwerp, Belgium; Department of Neurology and Alzheimer Center Groningen, University of Groningen and University Medical Center Groningen (UMCG), Groningen, The Netherlands.
| | - Erik Fransen
- StatUa Center for Statistics, University of Antwerp, Antwerp, Belgium.
| | | | | | - Rony Nuydens
- Laboratory of Cell Biology and Histology, University of Antwerp, Belgium.
| | | | | | - Winnok H De Vos
- Laboratory of Cell Biology and Histology, University of Antwerp, Belgium.
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Egimendia A, Minassian A, Diedenhofen M, Wiedermann D, Ramos-Cabrer P, Hoehn M. Aging Reduces the Functional Brain Networks Strength-a Resting State fMRI Study of Healthy Mouse Brain. Front Aging Neurosci 2019; 11:277. [PMID: 31680932 PMCID: PMC6798007 DOI: 10.3389/fnagi.2019.00277] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 09/26/2019] [Indexed: 11/20/2022] Open
Abstract
Resting-state functional magnetic resonance imaging (rsfMRI) is increasingly used to unravel the functional neuronal networks in health and disease. In particular, this technique of simultaneously probing the whole brain has found high interest in monitoring brain wide effects of cerebral disease and in evaluating therapeutic strategies. Such studies, applied in preclinical experimental mouse models, often require long-term observations. In particular during regeneration studies, easily several months of continuous monitoring are required to detect functional improvements. These long periods of following the functional deficits during disease evolution as well as the functional recoveries during therapeutic interventions represent a substantial fraction of the life span of the experimental animals. We have therefore aimed to decipher the role of healthy aging alone for changes in functional neuronal networks in mice, from developmental adolescence via adulthood to progressing aging. For this purpose, four different groups of C57Bl6 mice of varying age between 2 and 13 months were studied twice with 4 weeks separation using resting state fMRI at 9.4T. Dedicated data analysis including both Independent Component Analysis (ICA) followed by seed-based connectivity matrix compilation resulted in an inverse U-shape curve of functional connectivity (FC) strength in both the sensorimotor and default mode network (DMN). This inverse U-shape pattern presented a distinct maximum of FC strength at 8–9 months of age, followed by a continuous decrease during later aging phases. At progressed aging at 12–13 months, the reduction of connectivity strength varied between 25% and 70% with most connectivities showing a reduction in strength by approximately 50%. We recommend that these substantial age-dependent changes in FC strength must be considered in future longitudinal studies to discriminate focused disease-based functional deficits and therapy-related functional improvements from underlying independent age effects.
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Affiliation(s)
- Ander Egimendia
- Magnetic Resonance Imaging Laboratory, CIC biomaGUNE, Donostia-San Sebastián, Spain.,Multiple Sclerosis Unit, Biodonostia Health Institute, Donostia-San Sebastián, Spain
| | - Anuka Minassian
- In-vivo-NMR Laboratory, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Michael Diedenhofen
- In-vivo-NMR Laboratory, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Dirk Wiedermann
- In-vivo-NMR Laboratory, Max Planck Institute for Metabolism Research, Cologne, Germany
| | - Pedro Ramos-Cabrer
- Magnetic Resonance Imaging Laboratory, CIC biomaGUNE, Donostia-San Sebastián, Spain.,Ikerbasque-Basque Foundation for Science, Bilbao, Spain
| | - Mathias Hoehn
- In-vivo-NMR Laboratory, Max Planck Institute for Metabolism Research, Cologne, Germany
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