Rapid phagosome isolation enables unbiased multiomic analysis of human microglial phagosomes

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Microglia are key immune cells in the central nervous system (CNS), crucial for brain development, homeostasis, and disease.
• The composition, dynamics, and function of human microglial phagosomes in health and disease remain largely uncharacterized.

Purpose of the Study:

• To develop a method for isolating intact human microglial phagosomes for multiomic analysis.
• To investigate the molecular makeup and functional roles of phagosomes in human microglia under homeostatic and pathological conditions.

Main Methods:

• Developed a technique for rapid isolation of pure, intact phagosomes from human pluripotent stem cell-derived microglia and human brain biopsies.
• Performed unbiased multiomic analysis on isolated phagosomes to profile their protein content and identify functional components.

Main Results:

• Human microglial phagosomes are highly dynamic and equipped to detect environmental changes.
• Identified proteins involved in synapse homeostasis and implicated in brain pathologies within phagosomes.
• Discovered that phagosomes are the site of quinolinic acid storage and metabolism for cytoplasmic nicotinamide adenine dinucleotide (NAD+) generation.

Conclusions:

• Microglial phagosomes play a central role in maintaining brain homeostasis and responding to pathology.
• Phagosomes are critical hubs for metabolic processes, including NAD+ biosynthesis, within microglia.