Related Experiment Video

Updated: Jul 31, 2026

Correlative Light and Electron Microscopy to Study Microglial Interactions with β-Amyloid Plaques
10:52

Correlative Light and Electron Microscopy to Study Microglial Interactions with β-Amyloid Plaques

Published on: June 1, 2016

11.5K

APOEε4 associates with microglial activation independently of Aβ plaques and tau tangles

João Pedro Ferrari-Souza1,2, Firoza Z Lussier1,3, Douglas T Leffa1,4

  • 1Department of Psychiatry, University of Pittsburgh, Pittsburgh, PA, USA.

Science Advances
|April 5, 2023
PubMed

Insights

The apolipoprotein E ε4 (APOEε4) allele is linked to increased microglial activation in the brain, independent of amyloid-beta. This neuroinflammation contributes to tau accumulation and cognitive decline in Alzheimer's disease.

Area of Science:

  • Neuroscience
  • Genetics
  • Immunology

Background:

  • The apolipoprotein E ε4 (APOEε4) allele is a known genetic risk factor for Alzheimer's disease (AD).
  • Previous animal studies indicate APOEε4's role in early microglial activation, a key inflammatory process in the brain.
  • The precise mechanisms linking APOEε4 to neuroinflammation in living humans remain under investigation.

Purpose of the Study:

  • To investigate the association between APOEε4 status and microglial activation in individuals across the aging and AD spectrum.
  • To determine if APOEε4 influences microglial activation independently of amyloid-beta (Aβ) and tau pathology.
  • To explore the relationship between APOEε4-driven microglial activation, tau accumulation, neurodegeneration, and clinical symptoms.

Main Methods:

  • Positron emission tomography (PET) imaging was used to quantify amyloid-beta (Aβ), tau deposition, and microglial activation ([11C]PBR28) in 118 individuals.
  • Participants were genotyped for APOEε4 status.
  • Statistical analyses were performed to assess the association between APOEε4, microglial activation, Aβ, tau, and neurodegeneration, controlling for relevant factors.

Main Results:

  • APOEε4 carriers exhibited significantly higher microglial activation in medial temporal cortex regions associated with early Braak stages compared to non-carriers.
  • Microglial activation partially mediated the effects of APOEε4 on tau accumulation, independent of Aβ burden.
  • APOEε4-associated microglial activation patterns correlated with physiological APOE mRNA expression, suggesting a gene expression-driven vulnerability to neuroinflammation.

Conclusions:

  • The APOEε4 genotype promotes Alzheimer's disease pathogenesis through Aβ-independent microglial activation in brain regions prone to early tau deposition.
  • This neuroinflammatory pathway links APOEε4 to increased tau pathology, subsequent neurodegeneration, and clinical impairment.
  • Understanding this mechanism offers potential therapeutic targets for mitigating APOEε4's detrimental effects in AD.

More Related Videos

Generalized Psychophysiological Interaction PPI Analysis of Memory Related Connectivity in Individuals at Genetic Risk for Alzheimer's Disease09:38

Generalized Psychophysiological Interaction PPI Analysis of Memory Related Connectivity in Individuals at Genetic Risk for Alzheimer's Disease

Published on: November 14, 2017

15.0K
Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia07:18

Cell-based Assay to Study Antibody-mediated Tau Clearance by Microglia

Published on: November 9, 2018

8.4K

Related Concept Videos

Alzheimer's Disease: Overview01:26

Alzheimer's Disease: Overview

Alzheimer's Disease (AD) is a continually advancing neurodegenerative disorder, distinguished by escalating memory loss, cognitive dysfunction, and dementia. The disease unfolds in three stages: preclinical, mild cognitive impairment (MCI), and dementia. Its onset is insidious, and the progression gradual, with the cause not well explained by other disorders.
The clinical diagnosis of AD hinges on the presence of memory and other cognitive impairments. Biomarkers, such as changes in Aβ and tau...
Alzheimer Disease l: Introduction01:29

Alzheimer Disease l: Introduction

Alzheimer disease is a chronic, progressive, and irreversible neurodegenerative disorder and the most common cause of dementia in older adults. It leads to gradual neuronal loss, causing cognitive decline, behavioral changes, and loss of functional independence.Risk Factors and EtiologyThe disease is multifactorial. Age is the strongest risk factor, with prevalence doubling every 5 years after age 65. Genetic factors include mutations in genes such as APP, PSEN1, and PSEN2, which are associated...
Alzheimer Disease ll: Pathophysiology01:23

Alzheimer Disease ll: Pathophysiology

Alzheimer disease involves structural changes in the brain that begin long before symptoms appear. The most distinctive features are extracellular neuritic plaques and intracellular neurofibrillary tangles.Neuritic plaques form in the cerebral cortex and around blood vessels. These plaques contain a dense core of beta-amyloid (Aβ)—a toxic protein fragment that clumps outside neurons. The core is surrounded by damaged neuronal extensions, as well as reactive astrocytes and microglia. Abnormal...