Activated Microglial Cells Are Colocalized With Perivascular Deposits of Amyloid-β Protein in Alzheimer’s Disease Brain

Abstract

Background and Purpose Microglial cells are present in the center of senile plaques (SPs) in Alzheimer’s disease (AD) brain. Such a localization of microglial cells suggests that they are involved in the deposition or the clearance of amyloid-β protein (Aβ) in the brain. We examined their association with another type of parenchymal Aβ deposit, which is termed the perivascular deposits of Aβ (PAβ). Methods Thick sections from AD brain were stained with a three-color immunofluorescence method that labeled Aβ, activated microglial cells, and vascular endothelial cells simultaneously. Results Three-dimensional observation under a laser scanning microscope confirmed that perivascular aggregates of activated microglial cells were colocalized with PAβ. Conclusions Microglia occur in association with both SPs and PAβ, suggesting that they play important roles in the metabolism of Aβ in AD brain.