Localized microglia dysregulation impairs central nervous system myelination in development

Area of Science:

• Neuroscience
• Immunology
• Developmental Biology

Background:

• Myelination is crucial for central nervous system (CNS) development and function.
• The cellular and molecular mechanisms of human developmental myelination and its failures are not fully understood.

Purpose of the Study:

• To investigate the cellular and molecular mechanisms underlying human developmental myelination and its failures.
• To uncover the role of innate immune responses in impeded myelination during human brain development.

Main Methods:

• Digital spatial transcriptomics on human developing white matter.
• In vitro culture experiments using oligodendrocyte and microglia-conditioned media.

Main Results:

• Poorly myelinating areas show distinct Type II interferon signaling in microglia/macrophages.
• Increased mature oligodendrocytes in poorly myelinating areas fail to form myelin processes.
• Interferon-stimulated microglia impair oligodendrocyte myelin process formation in vitro.
• Osteopontin (SPP1) is upregulated in poorly myelinating brains, suggesting a biomarker.

Conclusions:

• A localized, dysregulated innate immune response, particularly Type II interferon signaling, is associated with impeded human myelination.
• Microglia-oligodendrocyte interactions and interferon signaling are critical for regulating myelination in the developing human brain.