Cited by 245Alzheimer's disease research and treatmentsNeuroinflammation and Neurodegeneration MechanismsExtracellular vesicles in disease

Plaque associated microglia hyper-secrete extracellular vesicles and accelerate tau propagation in a humanized APP mouse model

Open access
Clayton, Kevin, Delpech, Jean Christophe, Herron, Shawn, Iwahara, Naotoshi, Ericsson, Maria, Saito, Takashi, Saido, Takaomi C., Ikezu, Seiko +1 more·2021·Molecular Neurodegeneration

Published version of a preprint

Abstract

Abstract Background Recent studies suggest that microglia contribute to tau pathology progression in Alzheimer’s disease. Amyloid plaque accumulation transforms microglia, the primary innate immune cells in the brain, into neurodegenerative microglia (MGnD), which exhibit enhanced phagocytosis of plaques, apoptotic neurons and dystrophic neurites containing aggregated and phosphorylated tau (p-tau). It remains unclear how microglia promote disease progression while actively phagocytosing pathological proteins, therefore ameliorating pathology. Methods Adeno-associated virus expressing P301L tau mutant (AAV-P301L-tau) was stereotaxically injected into the medial entorhinal cortex (MEC) in C57BL/6 (WT) and humanized APP mutant knock-in homozygote ( App NL-G-F ) mice at 5 months of age. Mice were fed either chow containing a colony stimulating factor-1 receptor inhibitor (PLX5622) or control chow from 4 to 6 months of age to test the effect of microglia depletion. Animals were tested at 6 months of age for immunofluorescence, biochemistry, and FACS of microglia. In order to monitor microglial extracellular vesicle secretion in vivo, a novel lentiviral EV reporter system was engineered to express mEmerald-CD9 (mE-CD9) specifically in microglia, which was injected into the same region of MEC. Results Expressing P301L tau mutant in the MEC induced tau propagation to the granule cell layer of the hippocampal dentate gyrus, which was significantly exacerbated in App NL-G-F mice compared to WT control mice. Administration of PLX5622 depleted nearly all microglia in mouse brains and dramatically reduced propagation of p-tau in WT and to a greater extent in App NL-G-F mice, although it increased plaque burden and plaque-associated p-tau + dystrophic neurites. Plaque-associated MGnD microglia strongly expressed an EV marker, tumor susceptibility gene 101, indicative of heightened synthesis of EVs. Intracortical injection of mE-CD9 lentivirus successfully induced microglia-specific expression of mE-CD9 + EV particles, which were significantly enhanced in Mac2 + MGnD microglia compared to Mac2 − homeostatic microglia. Finally, consecutive intracortical injection of mE-CD9 lentivirus and AAV-P301L-tau into App NL-G-F mice revealed encapsulation of p-tau in microglia-specific mE-CD9 + EVs as determined by super-resolution microscopy and immuno-electron microscopy. Discussion Our findings suggest that MGnD microglia hyper-secrete p-tau + EVs while compacting Aβ plaques and clearing NP tau, which we propose as a novel mechanistic link between amyloid plaque deposition and exacerbation of tau propagation in App NL-G-F mice.

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Integrity signals

Registry

Crossref · 10.1186/s13024-021-00440-9

Cites

74 of 74 references verified0 citation errors · 0 not checkable

Statistics

Claims the paper makes

The claims and statistics of this paper haven’t been checked yet.

Run the check — free, no account needed. It reads the open-access text and checks the sources it cites.

A few free checks a day · papers already verified open instantly · results are public

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • Amyloid-β-associated microglia secrete extracellular vesicles that contain phosphorylated tau, and their depletion abrogated tau propagation.

    “Amyloid-β–associated microglia were shown to secrete extracellular vesicles that contain phosphorylated tau and their depletion abrogated tau propagation (Clayton et al., 2021).”

    From A novel molecular class that recruits HDAC/MECP2 complexes to PU.1 motifs reduces neuroinflammation (2023) · cites this paper as Clayton et al., 2021

    The Discussion (‘Microglia depletion and tauopathy’; page unavailable) reports that plaque-associated microglia secrete extracellular vesicles containing phosphorylated tau. The Results (‘Enhanced tau propagation and its reduction by CSF1R inhibition in AppNL-G-F mice’; page unavailable) say microglial depletion effectively suppressed tau propagation in the mouse model, but do not establish that it abrogated propagation entirely. (LLM, conf=0.86)

    Experimental — accuracy not yet measured
  • Microglia play essential role in plaque compaction between 4-6 months in mice.

    “demonstrating that microglia play an essential role in plaque compaction between four to six months of age in mice [61]”

    From Microglia and monocytes in inflammatory CNS disease: integrating phenotype and function (2022) · cites this paper as [61]

    The Results section (‘Microglia depletion increases plaque deposition’; page unavailable) strongly suggests that microglia have a significant role in plaque compaction in AppNL-G-F mice between 4 and 6 months of age. The claim overstates that finding as a demonstrated, essential role and omits the specific mouse model. (LLM, conf=0.86)

    Experimental — accuracy not yet measured
  • Microglia near amyloid plaques are three times as phagocytic and three times more likely to release tau-containing extracellular vesicles.

    “microglia were shown to be three times as phagocytic and three times more likely to release tau-containing extracellular vesicles when situated near amyloid plaques [61]”

    From Microglia and monocytes in inflammatory CNS disease: integrating phenotype and function (2022) · cites this paper as [61]

    The Results section (‘P-tau is encapsulated within microglia-specific EVs’) reports that MGnD microglia released roughly three times as many extracellular vesicles as homeostatic microglia, and that they internalized more p-tau and released more p-tau-containing vesicles. It does not report threefold phagocytosis or a threefold greater likelihood of releasing tau-containing vesicles; the threefold figure describes the number of vesicles released. (LLM, conf=0.88)

    Experimental — accuracy not yet measured
  • In the same study, an increase in plaque-associated tau in dystrophic neurites was found, indicating that microglia play a complex role in both the spread of tau and clearance of neuronal debris associated with pathological tau.

    “However, in the same study, an increase in plaque-associated tau in dystrophic neurites was found, indicating that microglia play a complex role in both the spread of tau and clearance of neuronal debris associated with pathological tau.”
  • Microglia depletion in 4-month-old APPNL−G−F mice resulted in reduced plaque compaction and increased plaque volume, number, and size.

    “microglia depletion in four-month-old humanized APP mutant knock-in homozygote (APPNL−G−F) mice resulted in reduced plaque compaction and increased plaque volume, number, and size”

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

The self-check needs the paper’s full text.

Cites

Flagged first, then by citations

Cited by

Sorted by citations

Authors
Clayton, K., Delpech, J. C., Herron, S., Iwahara, N., Ericsson, M., Saito, T., Saido, T. C., Ikezu, S., & Ikezu, T.
Affiliations
  • Boston University (US)
  • Harvard University (US)
  • RIKEN Center for Brain Science (JP)
Corresponding author
Ikezu, Tsuneya
Venue
Molecular Neurodegeneration
Published
2021-03-22
Volume
16
Issue
1
Pages
18-18
ISSN
1750-1326 (ISSN-L)
OpenAlex
W3137321433
Cited by
245
References
73
Citations by year
2026: 35 · 2025: 42 · 2024: 49 · 2023: 43 · 2022: 49 · 2021: 26 · 2013: 1
FWCI
26.24
Type
journal article
Language
en
Open access
Locations
  • Molecular Neurodegeneration (publishedVersion, cc-by)
  • bioRxiv (Cold Spring Harbor Laboratory) (acceptedVersion)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • HAL (submittedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • OpenBU (Boston University) (submittedVersion)
  • Oskar-Bordeaux (Universite de Bordeaux) (submittedVersion, cc-by)
Funders
  • Alzheimer's Association (DVT-14-320835)
  • BrightFocus Foundation (A2016551S)
  • Cure Alzheimer's Fund (N/A)
  • National Institute on Aging (R01 AG066429, RF1 AG054199, R56 AG057469, P30 AG0138423, F31 AG057170)
  • NIGMS (T32 GM008541)
Topics
  • Health Sciences › Medicine › Physiology › Alzheimer's disease research and treatments
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Extracellular vesicles in disease
Keywords
microglia, extracellular vesicles, tau propagation, Alzheimer's disease, amyloid plaques, PLX5622, CSF1R inhibition, microglial depletion, CD9, TSG101, medial entorhinal cortex, dentate gyrus, dystrophic neurites, tau phosphorylation, plaque-associated microglia, disease progression
MeSH terms
Extracellular Vesicles, Animals, Female, Genetic Vectors, Humans, Injections, Male, Mice, Inbred C57BL, Organic Chemicals, Recombinant Proteins, Receptors, Granulocyte-Macrophage Colony-Stimulating Factor, Neurites, Amyloid beta-Protein Precursor, tau Proteins, Point Mutation, Microglia, Entorhinal Cortex, Dentate Gyrus, Mutation, Missense, Mice, Gene Knock-In Techniques, Plaque, Amyloid, Protein Aggregation, Pathological

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review