Transcription factor p53 influences microglial activation phenotype

Area of Science:

• Neuroimmunology
• Neuroinflammation
• Molecular Neuroscience

Background:

• Innate immune responses in the central nervous system (CNS) influence neurodegenerative diseases.
• Microglia, the resident immune cells of the CNS, exhibit both pro-inflammatory and anti-inflammatory functions.
• Transcriptional regulation of microglial polarization remains poorly understood.

Purpose of the Study:

• To investigate the role of the transcription factor p53 in regulating microglial activation and function.
• To determine how p53 influences microglial responses to inflammatory stimuli.
• To explore the potential of targeting p53 for therapeutic interventions in neuroinflammatory conditions.

Main Methods:

• Utilized p53 knockout (p53(-/-)) and wild-type (p53(+/+)) mouse microglia.
• Stimulated microglia with interferon-γ (IFN-γ).
• Performed microarray analysis for global gene expression profiling.
• Assessed microglial phagocytic activity in vitro.
• Examined alternative activation markers (e.g., CD163) in vitro and in vivo.

Main Results:

• p53 deficiency blunted microglial response to IFN-γ, reducing pro-inflammatory gene expression and cytokine secretion.
• p53(-/-) microglia showed increased expression of genes linked to anti-inflammatory functions, phagocytosis, and tissue repair.
• p53(-/-) microglia exhibited enhanced phagocytic activity and markers of alternative macrophage activation.
• In HIV-associated neurocognitive disorders (HAND) brain tissue, p53 accumulation and CD163 expression marked distinct microglial subsets.

Conclusions:

• p53 promotes a pro-inflammatory microglial phenotype.
• Absence of p53 shifts microglia towards an alternative activation state, enhancing phagocytosis and anti-inflammatory functions.
• These findings highlight p53 as a key regulator of microglial polarization and a potential therapeutic target in neuroinflammation.