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Beckmann N, Neuhaus A, Zurbruegg S, Volkmer P, Patino C, Joller S, Feuerbach D, Doelemeyer A, Schweizer T, Rudin S, Neumann U, Berth R, Frieauff W, Gasparini F, Shimshek DR. Genetic models of cleavage-reduced and soluble TREM2 reveal distinct effects on myelination and microglia function in the cuprizone model. J Neuroinflammation 2023; 20:29. [PMID: 36755323 PMCID: PMC9909920 DOI: 10.1186/s12974-022-02671-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/12/2022] [Indexed: 02/10/2023] Open
Abstract
Triggering receptor expressed on myeloid cells 2 (TREM2) is a cell-surface immunoreceptor expressed on microglia, osteoclasts, dendritic cells and macrophages. Heterozygous loss-of-function mutations in TREM2, including mutations enhancing shedding form the cell surface, have been associated with myelin/neuronal loss and neuroinflammation in neurodegenerative diseases, such as Alzheimer`s disease and Frontotemporal Dementia. Using the cuprizone model, we investigated the involvement of soluble and cleavage-reduced TREM2 on central myelination processes in cleavage-reduced (TREM2-IPD), soluble-only (TREM2-sol), knockout (TREM2-KO) and wild-type (WT) mice. The TREM2-sol mouse is a new model with selective elimination of plasma membrane TREM2 and a reduced expression of soluble TREM2. In the acute cuprizone model demyelination and remyelination events were reflected by a T2-weighted signal intensity change in magnetic resonance imaging (MRI), most prominently in the external capsule (EC). In contrast to WT and TREM2-IPD, TREM2-sol and TREM2-KO showed an additional increase in MRI signal during the recovery phase. Histological analyses of TREM2-IPD animals revealed no recovery of neuroinflammation as well as of the lysosomal marker LAMP-1 and displayed enhanced cytokine/chemokine levels in the brain. TREM2-sol and, to a much lesser extent, TREM2-KO, however, despite presenting reduced levels of some cytokines/chemokines, showed persistent microgliosis and astrocytosis during recovery, with both homeostatic (TMEM119) as well as activated (LAMP-1) microglia markers increased. This was accompanied, specifically in the EC, by no myelin recovery, with appearance of myelin debris and axonal pathology, while oligodendrocytes recovered. In the chronic model consisting of 12-week cuprizone administration followed by 3-week recovery TREM2-IPD displayed sustained microgliosis and enhanced remyelination in the recovery phase. Taken together, our data suggest that sustained microglia activation led to increased remyelination, whereas microglia without plasma membrane TREM2 and only soluble TREM2 had reduced phagocytic activity despite efficient lysosomal function, as observed in bone marrow-derived macrophages, leading to a dysfunctional phenotype with improper myelin debris removal, lack of remyelination and axonal pathology following cuprizone intoxication.
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Affiliation(s)
- Nicolau Beckmann
- grid.419481.10000 0001 1515 9979Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Anna Neuhaus
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Stefan Zurbruegg
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Pia Volkmer
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Claudia Patino
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Stefanie Joller
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Dominik Feuerbach
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Arno Doelemeyer
- grid.419481.10000 0001 1515 9979Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Tatjana Schweizer
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Stefan Rudin
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Ulf Neumann
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Ramon Berth
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Wilfried Frieauff
- grid.419481.10000 0001 1515 9979Preclinical Safety, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Fabrizio Gasparini
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
| | - Derya R. Shimshek
- grid.419481.10000 0001 1515 9979Neuroscience, Novartis Institutes for BioMedical Research, Novartis Pharma AG, CH-4002 Basel, Switzerland
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Imaging in mice and men: Pathophysiological insights into multiple sclerosis from conventional and advanced MRI techniques. Prog Neurobiol 2019; 182:101663. [PMID: 31374243 DOI: 10.1016/j.pneurobio.2019.101663] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 06/17/2019] [Accepted: 07/17/2019] [Indexed: 01/16/2023]
Abstract
Magnetic resonance imaging (MRI) is the most important tool for diagnosing multiple sclerosis (MS). However, MRI is still unable to precisely quantify the specific pathophysiological processes that underlie imaging findings in MS. Because autopsy and biopsy samples of MS patients are rare and biased towards a chronic burnt-out end or fulminant acute early stage, the only available methods to identify human disease pathology are to apply MRI techniques in combination with subsequent histopathological examination to small animal models of MS and to transfer these insights to MS patients. This review summarizes the existing combined imaging and histopathological studies performed in MS mouse models and humans with MS (in vivo and ex vivo), to promote a better understanding of the pathophysiology that underlies conventional MRI, diffusion tensor and magnetization transfer imaging findings in MS patients. Moreover, it provides a critical view on imaging capabilities and results in MS patients and mouse models and for future studies recommends how to combine those particular MR sequences and parameters whose underlying pathophysiological basis could be partly clarified. Further combined longitudinal in vivo imaging and histopathological studies on rationally selected, appropriate mouse models are required.
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Beckmann N, Giorgetti E, Neuhaus A, Zurbruegg S, Accart N, Smith P, Perdoux J, Perrot L, Nash M, Desrayaud S, Wipfli P, Frieauff W, Shimshek DR. Brain region-specific enhancement of remyelination and prevention of demyelination by the CSF1R kinase inhibitor BLZ945. Acta Neuropathol Commun 2018; 6:9. [PMID: 29448957 PMCID: PMC5815182 DOI: 10.1186/s40478-018-0510-8] [Citation(s) in RCA: 89] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 01/26/2018] [Indexed: 11/10/2022] Open
Abstract
Multiple sclerosis (MS) is a chronic inflammatory disease affecting the central nervous system (CNS). While multiple effective immunomodulatory therapies for MS exist today, they lack the scope of promoting CNS repair, in particular remyelination. Microglia play a pivotal role in regulating myelination processes, and the colony-stimulating factor 1 (CSF-1) pathway is a key regulator for microglia differentiation and survival. Here, we investigated the effects of the CSF-1 receptor kinase inhibitor, BLZ945, on central myelination processes in the 5-week murine cuprizone model by non-invasive and longitudinal magnetic resonance imaging (MRI) and histology. Therapeutic 2-week BLZ945 treatment caused a brain region-specific enhancement of remyelination in the striatum/cortex, which was absent in the corpus callosum/external capsule. This beneficial effect correlated positively with microglia reduction, increased oligodendrocytes and astrogliosis. Prophylactic BLZ945 treatment prevented excessive demyelination in the corpus callosum by reducing microglia and increasing oligondendrocytes. In the external capsule oligodendrocytes were depleted but not microglia and a buildup of myelin debris and axonal damage was observed. A similar microglial dysfunction in the external capsule with an increase of myelin debris was obvious in triggering receptor expressed on myeloid cells 2 (TREM2) knock-out mice treated with cuprizone. Finally, therapeutic BLZ945 treatment did not change the disease course in experimental autoimmune encephalomyelitis mice, a peripherally driven neuroinflammation model. Taken together, our data suggest that a short-term therapeutic inhibition of the CSF-1 receptor pathway by BLZ945 in the murine cuprizone model enhances central remyelination by modulating neuroinflammation. Thus, microglia-modulating therapies could be considered clinically for promoting myelination in combination with standard-of-care treatments in MS patients.
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Affiliation(s)
- Nicolau Beckmann
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Elisa Giorgetti
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Anna Neuhaus
- Neuroscience, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Stefan Zurbruegg
- Neuroscience, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Nathalie Accart
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Paul Smith
- Autoimmunity, Transplantation and Inflammation, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
- Present address: Incyte, 1801 Augustine Cut-off, Wilmington, DE, 19803, USA
| | - Julien Perdoux
- Autoimmunity, Transplantation and Inflammation, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Ludovic Perrot
- Global Scientific Operations, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Mark Nash
- Musculoskeletal Diseases Area, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Sandrine Desrayaud
- PK Sciences, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Peter Wipfli
- PK Sciences, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Wilfried Frieauff
- Preclinical Safety, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland
| | - Derya R Shimshek
- Neuroscience, Novartis Institutes for BioMedical Research, 4002, Basel, Switzerland.
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Niendorf T, Pohlmann A, Reimann HM, Waiczies H, Peper E, Huelnhagen T, Seeliger E, Schreiber A, Kettritz R, Strobel K, Ku MC, Waiczies S. Advancing Cardiovascular, Neurovascular, and Renal Magnetic Resonance Imaging in Small Rodents Using Cryogenic Radiofrequency Coil Technology. Front Pharmacol 2015; 6:255. [PMID: 26617515 PMCID: PMC4642111 DOI: 10.3389/fphar.2015.00255] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 10/19/2015] [Indexed: 12/11/2022] Open
Abstract
Research in pathologies of the brain, heart and kidney have gained immensely from the plethora of studies that have helped shape new methods in magnetic resonance (MR) for characterizing preclinical disease models. Methodical probing into preclinical animal models by MR is invaluable since it allows a careful interpretation and extrapolation of data derived from these models to human disease. In this review we will focus on the applications of cryogenic radiofrequency (RF) coils in small animal MR as a means of boosting image quality (e.g., by supporting MR microscopy) and making data acquisition more efficient (e.g., by reducing measuring time); both being important constituents for thorough investigational studies on animal models of disease. This review attempts to make the (bio)medical imaging, molecular medicine, and pharmaceutical communities aware of this productive ferment and its outstanding significance for anatomical and functional MR in small rodents. The goal is to inspire a more intense interdisciplinary collaboration across the fields to further advance and progress non-invasive MR methods that ultimately support thorough (patho)physiological characterization of animal disease models. In this review, current and potential future applications for the RF coil technology in cardiovascular, neurovascular, and renal disease will be discussed.
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Affiliation(s)
- Thoralf Niendorf
- Berlin Ultrahigh Field Facility, Max Delbrück Center for Molecular Medicine in the Helmholtz AssociationBerlin, Germany
- German Centre for Cardiovascular ResearchBerlin, Germany
| | - Andreas Pohlmann
- Berlin Ultrahigh Field Facility, Max Delbrück Center for Molecular Medicine in the Helmholtz AssociationBerlin, Germany
| | - Henning M. Reimann
- Berlin Ultrahigh Field Facility, Max Delbrück Center for Molecular Medicine in the Helmholtz AssociationBerlin, Germany
| | | | - Eva Peper
- Berlin Ultrahigh Field Facility, Max Delbrück Center for Molecular Medicine in the Helmholtz AssociationBerlin, Germany
| | - Till Huelnhagen
- Berlin Ultrahigh Field Facility, Max Delbrück Center for Molecular Medicine in the Helmholtz AssociationBerlin, Germany
| | - Erdmann Seeliger
- Center for Cardiovascular Research, Institute of Physiology, Charité—Universitätsmedizin BerlinBerlin, Germany
| | - Adrian Schreiber
- Clinic for Nephrology and Intensive Care Medicine, Charité Medical Faculty and Experimental and Clinical Research CenterBerlin, Germany
| | - Ralph Kettritz
- Clinic for Nephrology and Intensive Care Medicine, Charité Medical Faculty and Experimental and Clinical Research CenterBerlin, Germany
| | | | - Min-Chi Ku
- Berlin Ultrahigh Field Facility, Max Delbrück Center for Molecular Medicine in the Helmholtz AssociationBerlin, Germany
| | - Sonia Waiczies
- Berlin Ultrahigh Field Facility, Max Delbrück Center for Molecular Medicine in the Helmholtz AssociationBerlin, Germany
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Fjær S, Bø L, Myhr KM, Torkildsen Ø, Wergeland S. Magnetization transfer ratio does not correlate to myelin content in the brain in the MOG-EAE mouse model. Neurochem Int 2015; 83-84:28-40. [PMID: 25744931 DOI: 10.1016/j.neuint.2015.02.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 01/29/2015] [Accepted: 02/24/2015] [Indexed: 12/27/2022]
Abstract
Magnetization transfer ratio (MTR) is a magnetic resonance imaging (MRI) method which may detect demyelination not detected by conventional MRI in the central nervous system of patients with multiple sclerosis (MS). A decrease in MTR value has previously been shown to correlate to myelin loss in the mouse cuprizone model for demyelination. In this study, we investigated the sensitivity of MTR for demyelination in the myelin oligodendrocyte (MOG) 1-125 induced experimental autoimmune encephalomyelitis (EAE) mouse model. A total of 24 female c57Bl/6 mice were randomized to a control group (N = 6) or EAE (N = 18). MTR images were obtained at a preclinical 7 Tesla Bruker MR-scanner before EAE induction (baseline), 17-19 days (midpoint) and 31-32 days (endpoint) after EAE induction. Mean MTR values were calculated in five regions of the brain and compared to weight, EAE severity score and myelin content assessed by immunostaining for proteolipid protein and luxol fast blue, lymphocyte and monocyte infiltration and iron deposition. Contrary to what was expected, MTR values in the EAE mice were higher than in the control mice at the midpoint and endpoint. No significant difference in myelin content was found according to histo- or immunohistochemistry. Changes in MTR values did not correlate to myelin content, iron content, lymphocyte or monocyte infiltration, weight or EAE severity scores. This suggest that MTR measures of brain tissue can give significant differences between control mice and EAE mice not caused by demyelination, inflammation or iron deposition, and may not be useful surrogate markers for demyelination in the MOG1-125 mouse model.
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Affiliation(s)
- Sveinung Fjær
- KG Jebsen Centre for MS-Research, Department of Clinical Medicine, University of Bergen, Bergen, Norway; The Norwegian Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway.
| | - Lars Bø
- KG Jebsen Centre for MS-Research, Department of Clinical Medicine, University of Bergen, Bergen, Norway; The Norwegian Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway
| | - Kjell-Morten Myhr
- KG Jebsen Centre for MS-Research, Department of Clinical Medicine, University of Bergen, Bergen, Norway; The Norwegian Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway
| | - Øivind Torkildsen
- KG Jebsen Centre for MS-Research, Department of Clinical Medicine, University of Bergen, Bergen, Norway; The Norwegian Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway
| | - Stig Wergeland
- KG Jebsen Centre for MS-Research, Department of Clinical Medicine, University of Bergen, Bergen, Norway; The Norwegian Multiple Sclerosis Competence Centre, Department of Neurology, Haukeland University Hospital, Bergen, Norway
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Johnson GA, Calabrese E, Little PB, Hedlund L, Qi Y, Badea A. Quantitative mapping of trimethyltin injury in the rat brain using magnetic resonance histology. Neurotoxicology 2014; 42:12-23. [PMID: 24631313 DOI: 10.1016/j.neuro.2014.02.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 02/24/2014] [Accepted: 02/28/2014] [Indexed: 10/25/2022]
Abstract
The growing exposure to chemicals in our environment and the increasing concern over their impact on health have elevated the need for new methods for surveying the detrimental effects of these compounds. Today's gold standard for assessing the effects of toxicants on the brain is based on hematoxylin and eosin (H&E)-stained histology, sometimes accompanied by special stains or immunohistochemistry for neural processes and myelin. This approach is time-consuming and is usually limited to a fraction of the total brain volume. We demonstrate that magnetic resonance histology (MRH) can be used for quantitatively assessing the effects of central nervous system toxicants in rat models. We show that subtle and sparse changes to brain structure can be detected using magnetic resonance histology, and correspond to some of the locations in which lesions are found by traditional pathological examination. We report for the first time diffusion tensor image-based detection of changes in white matter regions, including fimbria and corpus callosum, in the brains of rats exposed to 8 mg/kg and 12 mg/kg trimethyltin. Besides detecting brain-wide changes, magnetic resonance histology provides a quantitative assessment of dose-dependent effects. These effects can be found in different magnetic resonance contrast mechanisms, providing multivariate biomarkers for the same spatial location. In this study, deformation-based morphometry detected areas where previous studies have detected cell loss, while voxel-wise analyses of diffusion tensor parameters revealed microstructural changes due to such things as cellular swelling, apoptosis, and inflammation. Magnetic resonance histology brings a valuable addition to pathology with the ability to generate brain-wide quantitative parametric maps for markers of toxic insults in the rodent brain.
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Affiliation(s)
- G Allan Johnson
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, United States; Biomedical Engineering, Duke University, Durham, NC, United States.
| | - Evan Calabrese
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, United States; Biomedical Engineering, Duke University, Durham, NC, United States
| | | | - Laurence Hedlund
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, United States
| | - Yi Qi
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, United States
| | - Alexandra Badea
- Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, United States
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Weissleder R, Nahrendorf M, Pittet MJ. Imaging macrophages with nanoparticles. NATURE MATERIALS 2014; 13:125-38. [PMID: 24452356 DOI: 10.1038/nmat3780] [Citation(s) in RCA: 559] [Impact Index Per Article: 55.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Accepted: 09/17/2013] [Indexed: 05/02/2023]
Abstract
Nanomaterials have much to offer, not only in deciphering innate immune cell biology and tracking cells, but also in advancing personalized clinical care by providing diagnostic and prognostic information, quantifying treatment efficacy and designing better therapeutics. This Review presents different types of nanomaterial, their biological properties and their applications for imaging macrophages in human diseases, including cancer, atherosclerosis, myocardial infarction, aortic aneurysm, diabetes and other conditions. We anticipate that future needs will include the development of nanomaterials that are specific for immune cell subsets and can be used as imaging surrogates for nanotherapeutics. New in vivo imaging clinical tools for noninvasive macrophage quantification are thus ultimately expected to become relevant to predicting patients' clinical outcome, defining treatment options and monitoring responses to therapy.
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Affiliation(s)
- Ralph Weissleder
- 1] Center for Systems Biology, Massachusetts General Hospital, 185 Cambridge Street, CPZN 5206, Boston, Massachusetts 02114, USA [2] Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, Massachusetts 02115, USA [3] Department of Radiology, Massachusetts General Hospital, 32 Fruit Street, Boston, Massachusetts 02114, USA
| | - Matthias Nahrendorf
- 1] Center for Systems Biology, Massachusetts General Hospital, 185 Cambridge Street, CPZN 5206, Boston, Massachusetts 02114, USA [2] Department of Radiology, Massachusetts General Hospital, 32 Fruit Street, Boston, Massachusetts 02114, USA
| | - Mikael J Pittet
- 1] Center for Systems Biology, Massachusetts General Hospital, 185 Cambridge Street, CPZN 5206, Boston, Massachusetts 02114, USA [2] Department of Radiology, Massachusetts General Hospital, 32 Fruit Street, Boston, Massachusetts 02114, USA
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Mori Y, Murakami M, Arima Y, Zhu D, Terayama Y, Komai Y, Nakatsuji Y, Kamimura D, Yoshioka Y. Early pathological alterations of lower lumbar cords detected by ultrahigh-field MRI in a mouse multiple sclerosis model. Int Immunol 2013; 26:93-101. [DOI: 10.1093/intimm/dxt044] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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Bartzokis G, Lu PH, Heydari P, Couvrette A, Lee GJ, Kalashyan G, Freeman F, Grinstead JW, Villablanca P, Finn JP, Mintz J, Alger JR, Altshuler LL. Multimodal magnetic resonance imaging assessment of white matter aging trajectories over the lifespan of healthy individuals. Biol Psychiatry 2012; 72:1026-34. [PMID: 23017471 DOI: 10.1016/j.biopsych.2012.07.010] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Revised: 06/08/2012] [Accepted: 07/01/2012] [Indexed: 01/23/2023]
Abstract
BACKGROUND Postmortem and volumetric imaging data suggest that brain myelination is a dynamic lifelong process that, in vulnerable late-myelinating regions, peaks in middle age. We examined whether known regional differences in axon size and age at myelination influence the timing and rates of development and degeneration/repair trajectories of white matter (WM) microstructure biomarkers. METHODS Healthy subjects (n = 171) 14-93 years of age were examined with transverse relaxation rate (R(2)) and four diffusion tensor imaging measures (fractional anisotropy [FA] and radial, axial, and mean diffusivity [RD, AxD, MD, respectively]) of frontal lobe, genu, and splenium of the corpus callosum WM (FWM, GWM, and SWM, respectively). RESULTS Only R(2) reflected known levels of myelin content with high values in late-myelinating FWM and GWM regions and low ones in early-myelinating SWM. In FWM and GWM, all metrics except FA had significant quadratic components that peaked at different ages (R(2) < RD < MD < AxD), with FWM peaking later than GWM. Factor analysis revealed that, although they defined different factors, R(2) and RD were the metrics most closely associated with each other and differed from AxD, which entered into a third factor. CONCLUSIONS The R(2) and RD trajectories were most dynamic in late-myelinating regions and reflect age-related differences in myelination, whereas AxD reflects axonal size and extra-axonal space. The FA and MD had limited specificity. The data suggest that the healthy adult brain undergoes continual change driven by development and repair processes devoted to creating and maintaining synchronous function among neural networks on which optimal cognition and behavior depend.
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Affiliation(s)
- George Bartzokis
- Department of Psychiatry, The David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
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Increased body mass index is associated with a global and distributed decrease in white matter microstructural integrity. Psychosom Med 2012; 74:682-90. [PMID: 22879428 PMCID: PMC3586991 DOI: 10.1097/psy.0b013e318261909c] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE Obesity and decreased physical health are linked to deficits in several cognitive domains. The broad range of cognitive problems linked to obesity suggests a global mechanism that may interfere with multiple neural systems. We examined how variation in body mass index (BMI) is associated with the microstructural integrity of fiber connections in the human brain. METHODS White matter structure was measured using diffusion tensor imaging in 28 participants (mean age = 30 years) with BMI scores ranging from normal weight to obese (19.5-45.7 kg/m(2)) based on standard BMI criteria. RESULTS Using a whole-brain voxelwise analysis, we found that, across participants, the fractional anisotropy of white matter voxels parametrically decreased with increasing BMI (63% of white matter voxels). Midbrain and brainstem tracts were among the pathways most strongly associated with obesity (r = -0.18 to -0.33, df = 27, all p values < .05). We also observed a weaker overall diffusion signal in individuals with higher BMI than controls with normal weight (r = -0.14 to -0.71, df = 27, for 67% of fiber pathways tested, all p values < .05). After controlling for this decrease in general diffusivity, we found that decreases in fractional anisotropy stemmed from both a decrease in axial diffusivity (p < .05) and an increase in radial diffusivity (p < .05). CONCLUSIONS Our results show that increased BMI is globally associated with a reduction in white matter integrity throughout the brain, elucidating a potential mechanism by which changes in physical health may influence cognitive health.
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Waiczies H, Millward JM, Lepore S, Infante-Duarte C, Pohlmann A, Niendorf T, Waiczies S. Identification of cellular infiltrates during early stages of brain inflammation with magnetic resonance microscopy. PLoS One 2012; 7:e32796. [PMID: 22427887 PMCID: PMC3299701 DOI: 10.1371/journal.pone.0032796] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 01/31/2012] [Indexed: 11/18/2022] Open
Abstract
A comprehensive view of brain inflammation during the pathogenesis of autoimmune encephalomyelitis can be achieved with the aid of high resolution non-invasive imaging techniques such as microscopic magnetic resonance imaging (μMRI). In this study we demonstrate the benefits of cryogenically-cooled RF coils to produce μMRI in vivo, with sufficient detail to reveal brain pathology in the experimental autoimmune encephalomyelitis (EAE) model. We could visualize inflammatory infiltrates in detail within various regions of the brain, already at an early phase of EAE. Importantly, this pathology could be seen clearly even without the use of contrast agents, and showed excellent correspondence with conventional histology. The cryogenically-cooled coil enabled the acquisition of high resolution images within short scan times: an important practical consideration in conducting animal experiments. The detail of the cellular infiltrates visualized by in vivo μMRI allows the opportunity to follow neuroinflammatory processes even during the early stages of disease progression. Thus μMRI will not only complement conventional histological examination but will also enable longitudinal studies on the kinetics and dynamics of immune cell infiltration.
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Affiliation(s)
- Helmar Waiczies
- Experimental and Clinical Research Center, a joint cooperation between the Charité Medical Faculty and the Max-Delbrück Center for Molecular Medicine, Berlin, Germany.
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