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Updated: Apr 25, 2026
Quantitative 3D In Silico Modeling q3DISM of Cerebral Amyloid-beta Phagocytosis in Rodent Models of Alzheimer's Disease
Published on: December 26, 2016
MyD88 is dispensable for cerebral amyloidosis and neuroinflammation in APP/PS1 transgenic mice
Tara M Weitz1, David Gate1, Kavon Rezai-Zadeh2
1Zilkha Neurogenetic Institute, Department of Physiology and Biophysics, Keck School of Medicine of the University of Southern California, Los Angeles, California.
Abstract:
Activated microglia are associated with amyloid plaques in transgenic mouse models of cerebral amyloidosis and in human Alzheimer disease; yet, their implication in Alzheimer disease pathogenesis remains unclear. It has been suggested that microglia play dual roles depending on the context of activation, contributing negatively to disease pathogenesis by secreting proinflammatory innate cytokines or performing a beneficial role via phagocytosis of amyloid beta (Aβ) deposits. Toll-like receptors, most of which signal through the adaptor protein myeloid differentiation factor 88 (MyD88), have been suggested as candidate Aβ innate pattern recognition receptors. It was recently reported that MyD88 deficiency reduced brain amyloid pathology and microglial activation. To assess a putative role of MyD88 in cerebral amyloidosis and glial activation in APPswe/PS1ΔE9 (APP/PS1) mice, we crossed MyD88-deficient (MyD88(-/-)) mice with APP/PS1 mice, interbred first filial offspring, and studied APP/PS1 MyD88(+/+), APP/PS1 MyD88(+/-), and APP/PS1 MyD88(-/-) cohorts. Biochemical analysis of detergent-soluble and detergent-insoluble Aβ1-40 or Aβ1-42 in brain homogenates did not reveal significant between-group differences. Furthermore, no significant differences were observed on amyloid plaque load or soluble fibrillar Aβ by quantitative immunohistochemical analysis. In addition, neither activated microglia nor astrocytes differed among the three groups. These data suggest that MyD88 signaling is dispensable for Aβ-induced glial activation and does not significantly affect the nature or extent of cerebral β-amyloidosis in APP/PS1 mice.
Insights
Myeloid differentiation factor 88 (MyD88) signaling does not impact amyloid plaque development or glial cell activation in Alzheimer disease mouse models. These findings suggest MyD88 is not essential for cerebral beta-amyloidosis progression.
Area of Science:
- Neuroscience
- Immunology
- Genetics
Background:
- Activated microglia are linked to amyloid plaques in Alzheimer disease (AD) and mouse models, but their precise role is debated.
- Microglia may promote AD pathogenesis via inflammation or aid clearance through phagocytosis of amyloid beta (Aβ).
- Toll-like receptors, often signaling via myeloid differentiation factor 88 (MyD88), are implicated as Aβ pattern recognition receptors.
Purpose of the Study:
- To investigate the role of MyD88 signaling in cerebral amyloidosis and glial activation.
- To determine if MyD88 deficiency influences amyloid pathology and microglial/astrocyte responses in a mouse model of Alzheimer disease.
Main Methods:
- Crossed MyD88-deficient (MyD88(-/-)) mice with APPswe/PS1ΔE9 (APP/PS1) transgenic mice.
- Analyzed APP/PS1 MyD88(+/+), APP/PS1 MyD88(+/-), and APP/PS1 MyD88(-/-) cohorts.
- Quantified soluble and insoluble Aβ levels, amyloid plaque load, and glial activation (microglia and astrocytes).
Main Results:
- No significant differences were found in detergent-soluble or insoluble Aβ1-40/Aβ1-42 levels between the groups.
- Amyloid plaque load and soluble fibrillar Aβ did not differ significantly across genotypes.
- The activation status of microglia and astrocytes remained comparable among the three experimental groups.
Conclusions:
- MyD88 signaling is dispensable for Aβ-induced glial activation in APP/PS1 mice.
- MyD88 deficiency does not significantly alter the extent or nature of cerebral β-amyloidosis in this Alzheimer disease model.
