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Updated: Aug 19, 2026
Quantitative 3D In Silico Modeling (q3DISM) of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease
Published on: December 26, 2016
CD40 signaling regulates innate and adaptive activation of microglia in response to amyloid beta-peptide
Kirk P Townsend1, Terrence Town, Takashi Mori
1Neuroimmunology Laboratory, Department of Psychiatry, University of South Florida College of Medicine, Tampa, USA.
Abstract:
Although deposition of amyloid beta-peptide (Abeta) as Abeta plaques involves activation of microglia-mediated inflammatory responses, activated microglia ultimately fail to clear Abeta plaques in the brains of either Alzheimer's disease (AD) patients or AD mouse models. Mounting evidence suggests that chronic microglia-mediated immune response during Abeta deposition etiologically contributes to AD pathogenesis by promoting Abeta plaque formation. However, the mechanisms that govern microglia response in the context of cerebral Abeta/beta-amyloid pathology are not well understood. We show that ligation of CD40 by CD40L modulates Abeta-induced innate immune responses in microglia, including decreased microglia phagocytosis of exogenous Abeta(1-42) and increased production of pro-inflammatory cytokines. CD40 ligation in the presence of Abeta(1-42) leads to adaptive activation of microglia, as evidenced by increased co-localization of MHC class II with Abeta. To assess their antigen-presenting cell (APC) function, cultured microglia were pulsed with Abeta(1-42) in the presence of CD40L and co-cultured with CD4(+) T cells. Under these conditions, microglia stimulate T cell-derived IFN-gamma and IL-2 production, suggesting that CD40 signaling promotes the APC phenotype. These data provide a mechanistic explanation for our previous work showing decreased microgliosis associated with diminished cerebral Abeta/beta-amyloid pathology when blocking CD40 signaling in transgenic Alzheimer's mice.
Insights
Blocking CD40 signaling reduces Alzheimer's disease pathology by modulating microglia responses. This study reveals CD40L exacerbates amyloid beta deposition and inflammation, highlighting a therapeutic target.
Area of Science:
- Neuroscience
- Immunology
- Pathology
Background:
- Microglia, the brain's immune cells, are activated by amyloid beta (Abeta) deposition in Alzheimer's disease (AD).
- Despite activation, microglia fail to clear Abeta plaques, and chronic inflammation may contribute to AD pathogenesis.
- The precise mechanisms governing microglia responses to cerebral Abeta pathology remain unclear.
Purpose of the Study:
- To investigate the role of CD40 signaling in modulating microglia responses to Abeta.
- To understand how CD40 ligation affects Abeta-induced inflammation and phagocytosis by microglia.
- To explore the impact of CD40 signaling on microglia's antigen-presenting cell (APC) function in the context of Abeta.
Main Methods:
- Examined the effect of CD40 ligation (using CD40L) on Abeta(1-42)-induced microglia responses in vitro.
- Assessed microglia phagocytosis of Abeta and production of pro-inflammatory cytokines.
- Evaluated microglia's APC function by co-culturing them with CD4(+) T cells after pulsing with Abeta(1-42) and CD40L.
Main Results:
- CD40 ligation decreased microglia phagocytosis of Abeta(1-42) and increased pro-inflammatory cytokine production.
- CD40 ligation promoted an adaptive activation of microglia, indicated by increased MHC class II co-localization with Abeta.
- Microglia treated with Abeta(1-42) and CD40L stimulated T cell production of IFN-gamma and IL-2, demonstrating enhanced APC function.
Conclusions:
- CD40 signaling exacerbates Abeta-induced inflammatory responses and impairs microglia's ability to clear Abeta.
- CD40 signaling promotes microglia to act as antigen-presenting cells, potentially driving adaptive immune responses in AD.
- Blocking CD40 signaling offers a potential therapeutic strategy for reducing Abeta pathology and microgliosis in Alzheimer's disease.
