Cited by 100Alzheimer's disease research and treatmentsNeuroinflammation and Neurodegeneration MechanismsDementia and Cognitive Impairment Research

Cytokine-Mediated Inhibition of Fibrillar Amyloid-β Peptide Degradation by Human Mononuclear Phagocytes

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Yamamoto, Masaru, Kiyota, Tomomi, Walsh, Shannon M, Liu, Jianuo, Kipnis, Jonathan, Ikezu, Tsuneya·2008·The Journal of Immunology

Abstract

Vaccination therapy of AD animal models and patients strongly suggests an active role of brain mononuclear phagocytes in immune-mediated clearance of amyloid-beta peptides (Abeta) in brain. Although Abeta uptake by macrophages can be regulated by pro- and anti-inflammatory cytokines, their effects on macrophage-mediated Abeta degradation are poorly understood. To better understand this mechanism of degradation, we examined whether pro- and anti-inflammatory cytokines affect the degradation of Abeta using primary cultured human monocyte-derived macrophages (MDM) and microglia using pulse-chase analysis of fibrillar and oligomer (125)I-Abeta40 and Abeta42. Initial uptake of fibrillar Abeta40 and Abeta42 was 40% and its degradation was saturated by 120 h in both MDM and microglia, compared with an initial uptake of oligomeric Abeta less than 0.5% and saturation of degradation within 24 h. IFN-gamma increased the intracellular retention of fibrillar Abeta40 and Abeta42 by inhibiting degradation, whereas IL-4, IL-10, and TGF-beta1, but not IL-13 and IL-27, enhanced degradation. Fibrillar Abeta degradation in MDM is sensitive to lysosomal and insulin degrading enzyme inhibitors but insensitive to proteasomal and neprilysin inhibitors. IFN-gamma and TNF-alpha directly reduced the expression of insulin degrading enzyme and chaperone molecules (heat shock protein 70 and heat shock cognate protein 70), which are involved in refolding of aggregated proteins. Coculture of MDM with activated, but not naive T cells, suppressed Abeta degradation in MDM, which was partially blocked by a combination of neutralizing Abs against proinflammatory cytokines. These data suggest that proinflammatory cytokines suppress Abeta degradation in MDM, whereas select anti-inflammatory and regulatory cytokines antagonize these effects.

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Crossref · 10.4049/jimmunol.181.6.3877

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  • TNFα has been shown to directly reduce microglial expression of Aβ-degrading enzymes such as insulin-degrading enzyme and neprilysin.

    “TNF␣ has been shown to directly reduce microglial expression of A␤-degrading enzymes such as insulin-degrading enzyme and neprilysin.51,52”

    From CX3CR1 Deficiency Alters Microglial Activation and Reduces Beta-Amyloid Deposition in Two Alzheimer's Disease Mouse Models (2010) · cites this paper as [51]

    The Results section on IDE expression reports that TNF-α combined with IFN-γ reduced IDE expression in monocyte-derived macrophages, but TNF-α alone had no effect. The microglia Results section measures Aβ degradation, not enzyme expression; the copy does not report reduced microglial expression of IDE or neprilysin. (LLM, conf=0.90)

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  • In the AD brain, chronic activation of microglia is associated with inflammatory cytokines including TNFα that can substantially block the ability of microglia to remove or degrade Aβ.

    “Within the AD brain, there is a chronic activation of microglia associated with inflammatory cytokines including TNF␣ that can substantially block of ability of the microglia to remove 47,49,50 or degrade A␤. 51,52”

    From CX3CR1 Deficiency Alters Microglial Activation and Reduces Beta-Amyloid Deposition in Two Alzheimer's Disease Mouse Models (2010) · cites this paper as [51]

    The Results report that TNF-α reduced a measure of fibrillar Aβ42 degradation in cultured human microglia. The Discussion says pro-inflammatory cytokines suppressed Aβ degradation in microglia, mainly through IFN-γ, but that the microglial response was small. The study does not establish substantial inhibition in chronically activated microglia within the AD brain. (LLM, conf=0.88)

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Authors
Yamamoto, M., Kiyota, T., Walsh, S. M., Liu, J., Kipnis, J., & Ikezu, T.
Affiliations
  • University of Nebraska Medical Center (US)
  • University of Virginia (US)
Venue
The Journal of Immunology
Published
2008-09
Volume
181
Issue
6
Pages
3877-3886
ISSN
  • 0022-1767 (ISSN-L)
  • 1550-6606
OpenAlex
W1641618604
Cited by
100
References
38
Citations by year
2026: 1 · 2025: 7 · 2024: 9 · 2023: 4 · 2022: 7 · 2021: 4 · 2020: 2 · 2019: 4 · 2018: 1 · 2017: 5 · 2016: 7 · 2015: 7 · 2014: 6 · 2013: 6 · 2012: 6
FWCI
5.43
Type
journal article
Language
en
Open access
Locations
  • The Journal of Immunology (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • Nebraska Tobacco Settlement Biomedical Research Development Fund
  • National Institutes of Health (NS043985)
  • National Institute of Neurological Disorders and Stroke (P01NS043985)
Topics
  • Health Sciences › Medicine › Physiology › Alzheimer's disease research and treatments
  • Life Sciences › Neuroscience › Neurology › Neuroinflammation and Neurodegeneration Mechanisms
  • Health Sciences › Medicine › Psychiatry and Mental health › Dementia and Cognitive Impairment Research
Keywords
amyloid beta degradation, fibrillar amyloid-beta, monocyte-derived macrophages, microglia, inflammatory cytokines, anti-inflammatory cytokines, interferon-gamma, insulin-degrading enzyme, heat shock proteins, lysosomal degradation, Alzheimer's disease, amyloid-beta clearance, amyloid-beta oligomers
MeSH terms
Acetylation, Cells, Cultured, Humans, Iodine Radioisotopes, Lipoproteins, LDL, Macrophages, Peptide Fragments, Cytokines, Amyloid beta-Peptides, Microglia, Microscopy, Atomic Force, Inflammation Mediators, Coculture Techniques

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