Aβ stimulates microglial activation through antizyme-dependent downregulation of ornithine decarboxylase

Area of Science:

• Neuroscience
• Immunology
• Biochemistry

Background:

• Alzheimer's disease (AD) is a prevalent neurodegenerative disorder linked to amyloid-beta (Aβ) deposition and neuroinflammation.
• Microglial activation, particularly towards the M1 phenotype, plays a key role in AD pathogenesis.
• The precise mechanisms of Aβ-induced microglial M1 polarization and the role of arginine metabolism remain largely unknown.

Purpose of the Study:

• To investigate the role of Aβ in mediating microglial activation and polarization.
• To elucidate the involvement of arginine metabolism, specifically ornithine decarboxylase (ODC), in Aβ-induced microglial responses.
• To explore the potential of modulating ODC as a therapeutic strategy against Aβ-induced neuroinflammation and neurotoxicity.

Main Methods:

• In vitro and in vivo models were used to study microglial activation and polarization.
• The study focused on the regulation of arginine catabolism by ornithine decarboxylase (ODC) and its interaction with antizyme (AZ).
• Changes in microglial M1 markers and cytotoxicity were assessed under Aβ treatment and ODC modulation.

Main Results:

• Amyloid-beta (Aβ) treatment disrupted the balance between ODC and antizyme (AZ) in microglia, leading to altered ODC activity.
• This disruption promoted microglial activation and polarization towards the M1 phenotype.
• Restoring ODC protein levels inhibited Aβ-induced M1 markers and reduced microglial-mediated cytotoxicity.

Conclusions:

• Aβ contributes to M1-like microglial activation by disrupting the ODC-AZ balance in microglia.
• ODC plays a critical role in regulating microglial activation and neuroinflammation in the context of Alzheimer's disease.
• Targeting ODC represents a potential therapeutic avenue for mitigating Aβ-induced neuroinflammation and neurotoxicity in AD.