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Han X, Li PH, Wang S, Sanchez M, Aggarwal S, Blakely T, Schalek R, Meirovitch Y, Lin Z, Berger D, Wu Y, Aly F, Bay S, Delatour B, LaFaye P, Pfister H, Wei D, Jain V, Ploegh H, Lichtman J. A large-scale volumetric correlated light and electron microscopy study localizes Alzheimer's disease-related molecules in the hippocampus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.24.563674. [PMID: 37961104 PMCID: PMC10634883 DOI: 10.1101/2023.10.24.563674] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Connectomics is a nascent neuroscience field to map and analyze neuronal networks. It provides a new way to investigate abnormalities in brain tissue, including in models of Alzheimer's disease (AD). This age-related disease is associated with alterations in amyloid-β (Aβ) and phosphorylated tau (pTau). These alterations correlate with AD's clinical manifestations, but causal links remain unclear. Therefore, studying these molecular alterations within the context of the local neuronal and glial milieu may provide insight into disease mechanisms. Volume electron microscopy (vEM) is an ideal tool for performing connectomics studies at the ultrastructural level, but localizing specific biomolecules within large-volume vEM data has been challenging. Here we report a volumetric correlated light and electron microscopy (vCLEM) approach using fluorescent nanobodies as immuno-probes to localize Alzheimer's disease-related molecules in a large vEM volume. Three molecules (pTau, Aβ, and a marker for activated microglia (CD11b)) were labeled without the need for detergents by three nanobody probes in a sample of the hippocampus of the 3xTg Alzheimer's disease model mouse. Confocal microscopy followed by vEM imaging of the same sample allowed for registration of the location of the molecules within the volume. This dataset revealed several ultrastructural abnormalities regarding the localizations of Aβ and pTau in novel locations. For example, two pTau-positive post-synaptic spine-like protrusions innervated by axon terminals were found projecting from the axon initial segment of a pyramidal cell. Three pyramidal neurons with intracellular Aβ or pTau were 3D reconstructed. Automatic synapse detection, which is necessary for connectomics analysis, revealed the changes in density and volume of synapses at different distances from an Aβ plaque. This vCLEM approach is useful to uncover molecular alterations within large-scale volume electron microscopy data, opening a new connectomics pathway to study Alzheimer's disease and other types of dementia.
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Chourrout M, Sandt C, Weitkamp T, Dučić T, Meyronet D, Baron T, Klohs J, Rama N, Boutin H, Singh S, Olivier C, Wiart M, Brun E, Bohic S, Chauveau F. Virtual histology of Alzheimer's disease: Biometal entrapment within amyloid-β plaques allows for detection via X-ray phase-contrast imaging. Acta Biomater 2023; 170:260-272. [PMID: 37574159 DOI: 10.1016/j.actbio.2023.07.046] [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: 03/30/2023] [Revised: 07/21/2023] [Accepted: 07/25/2023] [Indexed: 08/15/2023]
Abstract
Amyloid-β (Aβ) plaques from Alzheimer's Disease (AD) can be visualized ex vivo in label-free brain samples using synchrotron X-ray phase-contrast tomography (XPCT). However, for XPCT to be useful as a screening method for amyloid pathology, it is essential to understand which factors drive the detection of Aβ plaques. The current study was designed to test the hypothesis that Aβ-related contrast in XPCT could be caused by Aβ fibrils and/or by metals trapped in the plaques. Fibrillar and elemental compositions of Aβ plaques were probed in brain samples from different types of AD patients and AD models to establish a relationship between XPCT contrast and Aβ plaque characteristics. XPCT, micro-Fourier-Transform Infrared spectroscopy and micro-X-Ray Fluorescence spectroscopy were conducted on human samples (one genetic and one sporadic case) and on four transgenic rodent strains (mouse: APPPS1, ArcAβ, J20; rat: TgF344). Aβ plaques from the genetic AD patient were visible using XPCT, and had higher β-sheet content and higher metal levels than those from the sporadic AD patient, which remained undetected by XPCT. Aβ plaques in J20 mice and TgF344 rats appeared hyperdense on XPCT images, while they were hypodense with a hyperdense core in the case of APPPS1 and ArcAβ mice. In all four transgenic strains, β-sheet content was similar, while metal levels were highly variable: J20 (zinc and iron) and TgF344 (copper) strains showed greater metal accumulation than APPPS1 and ArcAβ mice. Hence, a hyperdense contrast formation of Aβ plaques in XPCT images was associated with biometal entrapment within plaques. STATEMENT OF SIGNIFICANCE: The role of metals in Alzheimer's disease (AD) has been a subject of continuous interest. It was already known that amyloid-β plaques (Aβ), the earliest hallmark of AD, tend to trap endogenous biometals like zinc, iron and copper. Here we show that this metal accumulation is the main reason why Aβ plaques are detected with a new technique called X-ray phase contrast tomography (XPCT). XPCT enables to map the distribution of Aβ plaques in the whole excised brain without labeling. In this work we describe a unique collection of four transgenic models of AD, together with a human sporadic and a rare genetic case of AD, thus exploring the full spectrum of amyloid contrast in XPCT.
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Affiliation(s)
- Matthieu Chourrout
- Univ. Lyon, Lyon Neuroscience Research Center (CRNL); CNRS UMR5292; INSERM U1028, Univ. Lyon 1, Lyon, France
| | | | | | - Tanja Dučić
- ALBA-CELLS Synchrotron, MIRAS Beamline, Cerdanyola del Vallès, Spain
| | - David Meyronet
- Hospices Civils de Lyon, Neuropathology Department, Lyon, France; Univ. Lyon, Cancer Research Center of Lyon (CRCL); INSERM U1052; CNRS UMR5286, Univ. Lyon 1; Centre Léon Bérard, Lyon, France
| | | | - Jan Klohs
- ETH Zurich, Institute for Biomedical Engineering, Zurich, Switzerland
| | - Nicolas Rama
- Univ. Lyon, Cancer Research Center of Lyon (CRCL); INSERM U1052; CNRS UMR5286, Univ. Lyon 1; Centre Léon Bérard, Lyon, France
| | - Hervé Boutin
- Univ. Manchester, Faculty of Biology Medicine and Health, Wolfson Molecular Imaging Centre, Manchester, United Kingdom
| | - Shifali Singh
- Univ. Grenoble Alpes, Synchrotron Radiation for Biomedicine (STROBE); Inserm UA7, Grenoble, France
| | - Cécile Olivier
- Univ. Grenoble Alpes, Synchrotron Radiation for Biomedicine (STROBE); Inserm UA7, Grenoble, France
| | - Marlène Wiart
- Univ. Lyon, CarMeN Laboratory; INSERM U1060, INRA U1397, INSA Lyon, Univ. Lyon 1, Lyon, France; CNRS, France
| | - Emmanuel Brun
- Univ. Grenoble Alpes, Synchrotron Radiation for Biomedicine (STROBE); Inserm UA7, Grenoble, France
| | - Sylvain Bohic
- Univ. Grenoble Alpes, Synchrotron Radiation for Biomedicine (STROBE); Inserm UA7, Grenoble, France
| | - Fabien Chauveau
- Univ. Lyon, Lyon Neuroscience Research Center (CRNL); CNRS UMR5292; INSERM U1028, Univ. Lyon 1, Lyon, France; CNRS, France.
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