Abstract
Microglial cells clear the brain of pathogens and harmful debris, including amyloid-β (Aβ) deposits that are formed during Alzheimer’s disease (AD). We studied the expression of Msr1, Ager and Cd36 receptors involved in Aβ uptake and expression of Cd33 protein, which is considered a risk factor in AD. The effect of silver nanoparticles (AgNP) and cadmium telluride quantum dots (CdTeQD) on the expression of the above receptors and Aβ uptake by microglial cells was investigated. Absorption of Aβ and NP was confirmed by confocal microscopy. AgNP, but not CdTeQD, caused a decrease in Aβ accumulation. By using a specific inhibitor—polyinosinic acid—we demonstrated that Aβ and AgNP compete for scavenger receptors. Real-time PCR showed up-regulation of Cd33 and Cd36 gene expression after treatment with CdTeQD for 24 h. Analysis of the abundance of the receptors on the cell surface revealed that AgNP treatment significantly reduced the presence of Msr1, Cd33, Ager and Cd36 receptors (6 and 24 h), whereas CdTeQD increased the levels of Msr1 and Cd36 (24 h). To summarize, we showed that AgNP uptake competes with Aβ uptake by microglial cells and consequently can impair the removal of the aggregates. In turn, CdTeQD treatment led to the accumulation of proinflammatory Cd36 protein on the cell surface.
Highlights
Alzheimer’s disease (AD) is one of the most prevalent neurodegenerative disorders in the world.The main feature of the disease is the presence in the brain of extracellular amyloid-β (Aβ) deposits, called plaques, and intracellular neurofibrillary tangles, which are built by Tau protein
We showed that cadmium telluride quantum dots (CdTeQD) and AgNP were toxic to microglial cells; AgNP efficiently blocked Aβ uptake by microglia, impairing their function [23]
We have shown that AgNP at 50 μg mL−1 significantly diminished the accumulation of Aβ in the BV-2 cells, whereas CdTeQD (10 μg mL−1 ) did not have any impact on
Summary
The main feature of the disease is the presence in the brain of extracellular amyloid-β (Aβ) deposits, called plaques, and intracellular neurofibrillary tangles, which are built by Tau protein. Plaques are formed as a result of the defective cleavage of amyloid precursor protein [1,2]. The Aβ deposits are toxic to neurons as they generate oxidative stress and induce proinflammatory responses in the brain [2]. It is generally agreed that there is currently no effective cure for AD [3]. Drugs, which are available for patients, target the symptoms of AD and do not have any impact on the inhibition or diversion of the disease progress. There is a need for new drugs which are able to prevent plaque formation
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