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Updated: Jun 8, 2026
Quantitative 3D In Silico Modeling (q3DISM) of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease
Published on: December 26, 2016
CX3CR1 deficiency alters microglial activation and reduces beta-amyloid deposition in two Alzheimer's disease mouse
Sungho Lee1, Nicholas H Varvel, Megan E Konerth
1Lerner Research Institute, The Cleveland Clinic, Department of Neurosciences, Case Western Reserve University School of Medicine, 9500 Euclid Avenue, NC30, Cleveland, OH 44195-0001, USA.
Abstract:
Microglia, the primary immune effector cells in the brain, continually monitor the tissue parenchyma for pathological alterations and become activated in Alzheimer's disease. Loss of signaling between neurons and microglia via deletion of the microglial receptor, CX3CR1, worsens phenotypes in various models of neurodegenerative diseases. In contrast, CX3CR1 deficiency ameliorates pathology in murine stroke models. To examine the role of CX3CR1 in Alzheimer's disease-related β-amyloid pathology, we generated APPPS1 and R1.40 transgenic mouse models of Alzheimer's disease deficient for CX3CR1. Surprisingly, CX3CR1 deficiency resulted in a gene dose-dependent reduction in β-amyloid deposition in both the APPPS1 and R1.40 mouse models of AD. Immunohistochemical analysis revealed reduced staining for CD68, a marker of microglial activation. Furthermore, quantitative immunohistochemical analysis revealed reduced numbers of microglia surrounding β-amyloid deposits in the CX3CR1-deficient APPPS1 animals. The reduced β-amyloid pathology correlated with reduced levels of TNFα and CCL2 mRNAs, but elevated IL1β mRNA levels, suggesting an altered neuroinflammatory milieu. Finally, to account for these seemingly disparate results, both in vitro and in vivo studies provided evidence that CX3CL1/CX3CR1 signaling alters the phagocytic capacity of microglia, including the uptake of Aβ fibrils. Taken together, these results demonstrate that loss of neuron-microglial fractalkine signaling leads to reduced β-amyloid deposition in mouse models of AD that is potentially mediated by altered activation and phagocytic capability of CX3CR1-deficient microglia.
Insights
Loss of CX3CR1 signaling between neurons and microglia surprisingly reduced beta-amyloid deposition in Alzheimer's disease mouse models. This suggests CX3CR1 deficiency alters microglial activation and phagocytosis, impacting Alzheimer's pathology.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Microglia are brain immune cells that activate in Alzheimer's disease (AD).
- Neuron-microglial CX3CR1 signaling loss worsens neurodegeneration but improves stroke outcomes.
- The role of CX3CR1 in AD beta-amyloid pathology remains unclear.
Purpose of the Study:
- To investigate the impact of CX3CR1 deficiency on beta-amyloid pathology in mouse models of Alzheimer's disease.
Main Methods:
- Generated APPPS1 and R1.40 AD mouse models lacking CX3CR1.
- Utilized immunohistochemistry to assess beta-amyloid deposition and microglial activation (CD68).
- Analyzed mRNA levels of inflammatory cytokines (TNFα, CCL2, IL1β) and in vitro/in vivo phagocytosis assays.
Main Results:
- CX3CR1 deficiency dose-dependently reduced beta-amyloid deposition in both AD mouse models.
- Observed decreased microglial activation (CD68 staining) and fewer microglia around plaques.
- Found altered inflammatory gene expression and evidence that CX3CR1 signaling affects microglial phagocytosis of Aβ fibrils.
Conclusions:
- Loss of neuron-microglial CX3CR1 signaling reduces beta-amyloid deposition in AD mouse models.
- This reduction is potentially mediated by altered microglial activation and phagocytic capacity.
- Findings highlight CX3CR1's complex role in Alzheimer's pathogenesis.
