Human Down syndrome microglia are up for a synaptic feast.

Area of Science:

• Neuroscience
• Stem Cell Biology
• Genetics

Background:

• Down syndrome is associated with neurodevelopmental abnormalities and an increased risk of early-onset Alzheimer's disease.
• Microglia, the brain's immune cells, play a critical role in synaptic pruning and neuroinflammation.
• Cellular senescence, an aging process, contributes to various age-related diseases, including neurodegeneration.

Purpose of the Study:

• To investigate the function of microglia in the context of Down syndrome using human-mouse chimeric models.
• To explore the impact of Down syndrome on synaptic engulfment and cellular senescence in microglia.
• To identify potential therapeutic targets for Down syndrome-related neurological complications.

Main Methods:

• Generation of human-mouse chimeric brains engrafted with human induced pluripotent stem cell-derived microglia.
• Analysis of synaptic engulfment by microglia using advanced imaging techniques.
• Assessment of cellular senescence markers in microglia.
• Pharmacological inhibition of interferon signaling pathways.

Main Results:

• Human Down syndrome microglia exhibited enhanced synaptic engulfment compared to control microglia.
• Accelerated tau-induced cellular senescence was observed in Down syndrome microglia within the chimeric brains.
• Inhibition of interferon signaling significantly rescued both the developmental and tau-associated phenotypes of Down syndrome microglia.

Conclusions:

• Human Down syndrome microglia display distinct functional alterations, including heightened synaptic pruning and premature senescence.
• Interferon signaling is a key pathway involved in Down syndrome-related microglial dysfunction.
• Targeting interferon signaling presents a promising therapeutic avenue for addressing neurological aspects of Down syndrome.