An environment-dependent transcriptional network specifies human microglia identity

Area of Science:

• Neuroscience
• Immunology
• Genetics

Background:

• Microglia are crucial for central nervous system (CNS) homeostasis and neuronal function.
• The transcriptional regulation of human microglia phenotypes remains largely unexplored.
• Microglia are the primary immune cells of the brain.

Purpose of the Study:

• To investigate the transcriptional mechanisms specifying human microglia phenotypes.
• To compare microglia gene expression ex vivo and in vitro.
• To identify genes and pathways affected by environmental changes.

Main Methods:

• Transcriptome analysis of human microglia isolated from brain tissue.
• Epigenetic landscape examination of human microglia.
• Comparison of gene expression profiles between ex vivo and in vitro conditions.

Main Results:

• Transition to an in vitro environment caused rapid, extensive down-regulation of microglia-specific genes.
• These down-regulated genes were initially induced in primitive mouse macrophages migrating to the fetal brain.
• Altered expression of these gene subsets was observed in neurodegenerative and behavioral diseases and linked to noncoding risk variants.

Conclusions:

• Microglia possess an environment-dependent transcriptional network that defines their specific gene expression programs.
• These findings provide insights into the plasticity of microglia and their roles in CNS homeostasis and disease.
• Understanding these transcriptional changes is crucial for deciphering microglia functions in human brain disorders.