1. Characterization of cortico-meningeal translocator protein expression in multiple sclerosis.
- Author
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Herranz E, Treaba CA, Barletta VT, Mehndiratta A, Ouellette R, Sloane JA, Ionete C, Babu S, Mastantuono M, Magon S, Loggia ML, Makary MM, Hooker JM, Catana C, Kinkel RP, Nicholas R, Klawiter EC, Magliozzi R, and Mainero C
- Subjects
- Humans, Female, Male, Middle Aged, Adult, Aged, Cerebral Cortex metabolism, Cerebral Cortex diagnostic imaging, Cerebral Cortex pathology, Multiple Sclerosis, Relapsing-Remitting metabolism, Multiple Sclerosis, Relapsing-Remitting diagnostic imaging, Multiple Sclerosis, Relapsing-Remitting pathology, Magnetic Resonance Imaging, Multiple Sclerosis, Chronic Progressive metabolism, Multiple Sclerosis, Chronic Progressive diagnostic imaging, Multiple Sclerosis, Chronic Progressive pathology, Acetamides, Pyridines, Receptors, GABA metabolism, Receptors, GABA genetics, Positron-Emission Tomography methods, Meninges metabolism, Meninges diagnostic imaging, Meninges pathology, Multiple Sclerosis metabolism, Multiple Sclerosis diagnostic imaging, Multiple Sclerosis pathology
- Abstract
Compartmentalized meningeal inflammation is thought to represent one of the key players in the pathogenesis of cortical demyelination in multiple sclerosis. PET targeting the 18 kDa mitochondrial translocator protein (TSPO) is a molecular-specific approach to quantifying immune cell-mediated density in the cortico-meningeal tissue compartment in vivo. This study aimed to characterize cortical and meningeal TSPO expression in a heterogeneous cohort of multiple sclerosis cases using in vivo simultaneous MR-PET with 11C-PBR28, a second-generation TSPO radioligand, and ex vivo immunohistochemistry. Forty-nine multiple sclerosis patients (21 with secondary progressive and 28 with relapsing-remitting multiple sclerosis) with mixed or high affinity binding for 11C-PBR28 underwent 90-min 11C-PBR28 simultaneous MR-PET. Tracer binding was measured using 60-90 min normalized standardized uptake value ratios sampled at mid-cortical depth and ∼3 mm above the pial surface. Data in multiple sclerosis patients were compared to 21 age-matched healthy controls. To characterize the nature of 11C-PBR28 PET uptake, the meningeal and cortical lesion cellular expression of TSPO was further described in post-mortem brain tissue from 20 cases with secondary progressive multiple sclerosis and five age-matched healthy donors. Relative to healthy controls, patients with multiple sclerosis exhibited abnormally increased TSPO signal in the cortex and meningeal tissue, diffusively in progressive disease and more localized in relapsing-remitting multiple sclerosis. In multiple sclerosis, increased meningeal TSPO levels were associated with increased Expanded Disability Status Scale scores (P = 0.007, by linear regression). Immunohistochemistry, validated using in situ sequencing analysis, revealed increased TSPO expression in the meninges and adjacent subpial cortical lesions of post-mortem secondary progressive multiple sclerosis cases relative to control tissue. In these cases, increased TSPO expression was related to meningeal inflammation. Translocator protein immunostaining was detected on meningeal MHC-class II+ macrophages and cortical-activated MHC-class II+ TMEM119+ microglia. In vivo arterial blood data and neuropathology showed that endothelial binding did not significantly account for increased TSPO cortico-meningeal expression in multiple sclerosis. Our findings support the use of TSPO-PET in multiple sclerosis for imaging in vivo inflammation in the cortico-meningeal brain tissue compartment and provide in vivo evidence implicating meningeal inflammation in the pathogenesis of the disease., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)
- Published
- 2024
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