Cited by 371Alzheimer's disease research and treatmentsNeuroinflammation and Neurodegeneration MechanismsIL-33, ST2, and ILC Pathways

IL-33 ameliorates Alzheimer's disease-like pathology and cognitive decline

Open access
Fu, Amy K. Y., Hung, Kwok-Wang, Yuen, Michael Y. F., Zhou, Xiaopu, Mak, Deejay S. Y., Chan, Ivy C. W., Cheung, Tom H., Zhang, Baorong +3 more·2016·Proceedings of the National Academy of Sciences

Abstract

Significance: Dysfunction of the innate immune system is involved in the pathogenesis of Alzheimer’s disease (AD); however, the pathophysiological mechanisms underlying these dysfunctions are unclear. Here we report that stimulation of IL-33/ST2 signaling rescues memory deficits and reduces the accumulation of β-amyloid in APP/PS1 mice that exhibit select pathologies associated with AD. Although impaired IL-33/ST2 signaling is associated with early progression of AD, IL-33 injection rescues contextual memory deficits and reduces the accumulation of β-amyloid in APP/PS1 mice. IL-33 skews the microglia toward an alternative activation state with enhanced Aβ phagocytic capacity and elevated antiinflammatory gene expression, which results in a decreased proinflammatory response in the brain. Thus, this study suggests that IL-33 can be developed as a new therapeutic intervention for AD.

AI snapshot

Written from the paper’s full text.

TL;DR

IL-33 administration reversed synaptic plasticity and contextual memory deficits and reduced amyloid pathology in APP/PS1 mice by enhancing microglial Aβ phagocytosis and shifting microglia/macrophages toward an antiinflammatory phenotype. The findings support IL-33/ST2 signaling as a potential therapeutic target in Alzheimer’s disease.

Key findings

  • In 6- to 7-mo-old APP/PS1 mice, i.p. IL-33 (200 ng for 2 d) dramatically reversed impaired hippocampal LTP and restored contextual fear memory at 7 d after shock.
  • IL-33 reduced soluble Aβ in cortices of 10-mo-old APP/PS1 mice by 54 ± 9% (n = 3 experiments); soluble Aβx-40 and Aβx-42 decreased by ∼50% and ∼30%, respectively. It also reduced 4G8-stained amyloid plaques in 12-mo-old APP/PS1 mice, and intracerebroventricular sST2 abolished this plaque reduction.
  • IL-33 increased Aβ phagocytosis: methoxy-X04-labeled Aβ was detected in ∼33% of CD11b+ myeloid cells from APP/PS1 cortices, rising to ∼47% after IL-33; Aβ uptake by resident microglia increased by ∼80%, while infiltrating monocytes remained relatively stable.
  • IL-33 increased antiinflammatory Arg1 and Fizz1 mRNA in CD11b+ myeloid cells and suppressed proinflammatory IL-1β, IL-6, and NLRP3 in APP/PS1 cortices; ST2-deficient microglia abolished IL-33-stimulated Aβ uptake.

Methods

  • Mouse models: APP/PS1, 5XFAD, and St2−/− mice; WT C57BL/6 controls. In vivo IL-33 was given i.p. at 200 ng per mouse for 2 consecutive days, with some experiments using intracerebroventricular sST2 via osmotic pumps.
  • Outcomes included hippocampal LTP at SC-CA1 synapses, open field habituation, contextual fear conditioning, soluble/insoluble Aβ by Western blot and ELISA, 4G8 plaque immunohistochemistry, microglial Aβ phagocytosis by flow cytometry, and inflammatory gene expression by ddPCR/qRT-PCR.
  • Human data: serum sST2 measured in 17 healthy controls and 18 patients with MCI (Han Chinese, age ≥60 y), with clinical diagnosis by NINCDS-ADRDA criteria.

Limitations

  • The paper does not include a dedicated limitations section; it states that whether IL-33/ST2 suppression of proinflammatory gene production via MyD88 competition mediates the observed effects “awaits further study,” and that further phenotypic characterization of the microglial subset with increased Aβ phagocytic capacity is needed.
  • Evident from the text: the therapeutic evidence is primarily from transgenic mouse models, and the human data are limited to cross-sectional serum sST2 in small groups (17 controls, 18 MCI), not IL-33 treatment or clinical outcomes.
  • Evident from the text: long-term safety, dosing durability, and whether the murine findings extrapolate to human AD are not established.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1073/pnas.1604032113

Cites

60 of 60 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 5 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    IL-33 injection increases the proportion of CD11b+ cells exhibiting methoxy-X04 fluorescence to approximately 47% in APP/PS1 mice.

    “IL-33 injection further increased the proportion of CD11b + cells exhibiting methoxy-X04 fluorescence (∼47%; Fig. 3 F and G).”
    Quote in the paperSubstantial claim
  • Findingown data

    IL-33 administration significantly increases Aβ phagocytic uptake by resident microglia by approximately 80% in APP/PS1 mice.

    “IL-33 administration significantly increased Aβ phagocytic uptake by resident microglia by ∼80%, whereas the percentage of Aβ-containing infiltrating monocytes remained relatively stable (Fig. 3 H and I and SI Appendix, Fig. S8 E-G).”
    Quote in the paperSubstantial claim
  • Findingown data

    IL-33 administration reduces soluble Aβ x-40 and Aβ x-42 species in the cortices of 10-mo-old APP/PS1 mice.

    “Specifically, soluble Aβ x-40 and Aβ x-42 species, which play major synaptotoxic roles in AD (21), were decreased by ∼50% and ∼30%, respectively, in the cortices of 10-mo-old IL-33-administered APP/PS1 mice (Fig. 2B).”
    Quote in the paperSubstantial claim
  • Findingown data
    § IL-33 ameliorates Alzheimer's disease-like pathology and cognitive decline

    IL-33 administration reduces soluble Aβ levels in the cortices of APP/PS1 mice.

    “IL-33 administration reduces soluble Aβ levels and amyloid plaque deposition by promoting the recruitment and Aβ phagocytic activity of microglia; this is mediated by ST2/p38 signaling activation.”
    Quote in the paperSubstantial claim
  • Findingown data

    IL-33 administration increases CD68 expression in Iba1+ myeloid cells in close contact with amyloid plaques in APP/PS1 mice.

    “IL-33 administration increased CD68 expression in Iba1 + myeloid cells, that were in close contact with amyloid plaques (Fig. 3E).”
    Quote in the paperSubstantial claim
  • The quote only partly states this claim. 3
  • May combine two claims. 6
  • Classified as probably not a substantial claim. 2
  • The quote only partly states this claim.

    Findingown data

    IL-33 administration rescues LTP impairment in APP/PS1 mutant mice at 6 to 7 months of age in the hippocampal CA1 region.

    “IL-33 rescues LTP impairment in APP/PS1 mutant mice.”
    Quote in the paperSubstantial claim
  • The quote only partly states this claim.

    Findingown data

    IL-33 ameliorates memory retrieval deficits of APP/PS1 mice in fear conditioning tests at 1 day after electric shock.

    “IL-33 ameliorates memory retrieval deficits of APP/PS1 mice in fear conditioning (FC) tests.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingown data

    At the concentration used (200 ng i.p. daily for 2 d), IL-33 does not affect general health or plasma histamine level in WT or APP/PS1 mice.

    “At the concentration used (200 ng i.p. daily for 2 d), IL-33 did not affect the general health or plasma histamine level in either WT or APP/PS1 mice (SI Appendix, Fig. S4).”
    Quote in the paperNot a substantial claim
  • The quote only partly states this claim.

    Findingown data

    IL-33 ameliorates memory retrieval deficits of APP/PS1 mice in fear conditioning tests at 7 days after electric shock.

    “IL-33 ameliorates memory retrieval deficits of APP/PS1 mice in fear conditioning (FC) tests.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationown data

    IL-33 administration mitigates amyloid plaque pathology in APP/PS1 mice through enhancement of Aβ phagocytosis by resident microglia and Aβ clearance, probably by increasing neprilysin levels.

    “Taken together, our results demonstrate that IL-33 administration mitigates the amyloid plaque pathology in APP/PS1 mice through the enhancement of Aβ phagocytosis by resident microglia and Aβ clearance, probably by increasing neprilysin levels.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim.

    Study design and conductnone given

    Investigators who performed the electrophysiological, immunohistochemical, RNA expression, and flow cytometry analyses and the behavioral tests were blinded to the genotypes of the mice and treatment conditions.

    “The investigators who performed the electrophysiological, immunohistochemical, RNA expression, and flow cytometry analyses and the behavioral tests were blinded to the genotypes of the mice and treatment conditions.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationown data

    IL-33 administration ameliorates synaptic impairment and behavioral deficits in APP/PS1 mice.

    “IL-33 administration ameliorates synaptic impairment and behavioral deficits in APP/PS1 mice.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationown data

    IL-33 treatment reverses contextual memory deficits in APP/PS1 mice, probably through ameliorating hippocampal synaptic dysfunctions.

    “These data suggest that IL-33 treatment reverses contextual memory deficits in APP/PS1 mice, probably through ameliorating the hippocampal synaptic dysfunctions.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationown data

    IL-33 administration reduces soluble Aβ levels and Aβ plaques in APP/PS1 mice.

    “IL-33 administration reduces soluble Aβ levels and Aβ plaques in APP/PS1 mice.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    The purity of microglia/infiltrating monocyte isolation was routinely greater than 90%, as determined by fluorescence staining for CD11b and flow cytometry analysis.

    “The purity of microglia/infiltrating monocyte isolation was routinely >90% as determined by fluorescence staining for CD11b and flow cytometry analysis.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationown data

    IL-33 treatment switches microglia/macrophages to an alternative activation phenotype, resulting in a reduction of the proinflammatory response in AD mouse brains.

    “Furthermore, IL-33 treatment switches the microglia/macrophages to an alternative activation phenotype, resulting in a reduction of the proinflammatory response in the AD mouse brains.”
    Quote in the paperSubstantial claim
11 of 11
  • The paper relies on this without support.

    There is no effective therapy for AD.

    “There is no effective therapy for AD, in part because of our limited knowledge of its underlying pathophysiological mechanisms.”
  • The paper relies on this without support.

    The mechanisms underlying the onset and progression of AD remain unclear.

    “The mechanisms underlying the onset and progression of AD remain unclear.”
2 of 2

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?

  • The authors' results support previous studies showing improved behaviour in AD mouse models associated with enhanced microglial amyloid plaque phagocytosis in response to scanning ultrasound and treatment with IL-33.

    “Our results support previous studies showing improved behaviour in AD mouse models associated with enhanced microglial amyloid plaque phagocytosis in response to scanning ultrasound69, and treatment with IL-33 that signals exclusively via MyD8870.”

    From Transcriptional signature in microglia associated with Aβ plaque phagocytosis (2021) · cites this paper as [70]

    The paper reports that IL-33 treatment reverses cognitive deficits in APP/PS1 mice and enhances microglial Aβ phagocytosis (introductory summary and Results, Fig. 3). Its Discussion says ST2 activation recruits MyD88, but does not establish that IL-33 signals exclusively through MyD88. The scanning-ultrasound finding is attached to a different citation and is not assessed here. (LLM, conf=0.86)

    Experimental — accuracy not yet measured
  • CD45 is differentially expressed on microglia (CD45lo/CD11b+) and recruited myeloid cells (CD45hi/CD11b+), and this distinction is commonly used in flow cytometry to distinguish recruited myeloid cells from resident microglia in various disease states.

    “CD45 is differentially expressed on microglia (CD45lo/CD11b+) and recruited myeloid cells (CD45hi/CD11b+), and this distinction is commonly used in flow cytometry experiments to distinguish recruited myeloid cells from resident microglia in various disease states [27, 40, 41].”

    From IL-1β-driven amyloid plaque clearance is associated with an expansion of transcriptionally reprogrammed microglia (2019) · cites this paper as [27]

    Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

    Experimental — accuracy not yet measured
  • IL-33 administration ameliorated memory deficits and reduced Aβ deposition in the APP/PS1 mouse model.

    “Furthermore, IL-33 administration ameliorated memory deficits and reduced Aβ deposition in the APP/PS1 mouse model (54).”
  • Activation of microglial cells by inflammatory molecules has been shown to enhance Aβ clearance by microglia.

    “Strikingly, activation of microglial cells by inflammatory molecules has been shown to enhance Aβ clearance by microglia [3, 26, 27].”
  • IL-33 ameliorated AD-associated phenotypes by promoting anti-inflammatory functions, which included induction of Arg1.

    “IL-33 ameliorated AD-associated phenotypes by promoting anti-inflammatory functions, which included induction of Arg1 (80).”

Cites

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Authors
Fu, A. K. Y., Hung, K.-W., Yuen, M. Y. F., Zhou, X., Mak, D. S. Y., Chan, I. C. W., Cheung, T. H., Zhang, B., Fu, W.-Y., Liew, F. Y., & Ip, N. Y.
Affiliations
  • Hong Kong University of Science and Technology (HK)
  • Second Affiliated Hospital of Zhejiang University (CN)
  • Soochow University (CN)
Venue
Proceedings of the National Academy of Sciences
Published
2016-04-18
Volume
113
Issue
19
Pages
E2705-13
ISSN
  • 0027-8424 (ISSN-L)
  • 1091-6490
OpenAlex
W2342031861
Cited by
369
References
61
Citations by year
2026: 18 · 2025: 41 · 2024: 45 · 2023: 39 · 2022: 33 · 2021: 48 · 2020: 40 · 2019: 24 · 2018: 35 · 2017: 31 · 2016: 14 · 2012: 1
FWCI
27.92
Type
journal article
Language
en
Open access
Locations
  • Proceedings of the National Academy of Sciences (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
  • ENLIGHTEN (Jurnal Bimbingan dan Konseling Islam) (acceptedVersion)
  • Rare & Special e-Zone (The Hong Kong University of Science and Technology) (submittedVersion)
Topics
  • Health Sciences › Medicine › Physiology › Alzheimer's disease research and treatments
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
  • Life Sciences › Immunology and Microbiology › Immunology › IL-33, ST2, and ILC Pathways
Keywords
IL-33, Alzheimer's disease, soluble ST2, amyloid-beta, microglial activation, innate immunity, synaptic plasticity, memory impairment, APP/PS1 mice, amyloid plaques, p38 MAPK signaling, microglial polarization, neuroinflammation, NLRP3 inflammasome, IL-1β, interleukin-6
MeSH terms
Interleukin-33, Alzheimer Disease, Animals, Brain, Cognition Disorders, Female, Male, Mice, Transgenic, Cytokines, Treatment Outcome, Neuroprotective Agents, Mice

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