Systemic inflammation impairs microglial Aβ clearance through NLRP3 inflammasome

Area of Science:

• Neuroscience
• Immunology
• Pathology

Background:

• Alzheimer's disease (AD) is the most common dementia, characterized by amyloid-beta plaques and tau tangles.
• Neuroinflammation, involving microglia, is increasingly recognized as a key pathological component in AD.
• Systemic inflammation is linked to cognitive decline in neurodegenerative diseases like AD.

Purpose of the Study:

• To investigate in vivo microglial morphological and functional changes following peripheral immune challenge in aging and AD contexts.
• To evaluate the role of the NLRP3 inflammasome in mediating microglial responses to systemic inflammation in AD.

Main Methods:

• Utilized 2-photon laser scanning microscopy to monitor microglia in vivo.
• Administered lipopolysaccharide (LPS) as a peripheral immune challenge.
• Compared responses in wild-type and APP/PS1 mice (AD model), including NLRP3 inflammasome knockout.

Main Results:

• Lipopolysaccharide challenge induced microglial process retraction and reduced coverage, which resolved by 10 days.
• Systemic inflammation impaired microglial amyloid-beta clearance in APP/PS1 mice.
• NLRP3 inflammasome knockout largely prevented LPS-induced microglial alterations and amyloid pathology.

Conclusions:

• Peripheral immune challenges significantly impact microglial behavior and amyloid pathology in AD models.
• The NLRP3 inflammasome plays a critical role in mediating these detrimental effects.
• NLRP3 inhibition presents a potential therapeutic strategy to mitigate brain inflammation during systemic infections in AD.