Maternal immunoglobulin G affects brain development of mouse offspring

Area of Science:

• Neuroscience
• Immunology
• Developmental Biology

Background:

• Maternal immunoglobulin G (IgG) is transferred via breast milk, contributing to infant immunity.
• The role of maternal IgG in early childhood brain development remains largely unexplored.
• Microglia, the brain's resident immune cells, are implicated in neurodevelopmental processes.

Purpose of the Study:

• To investigate the presence and impact of maternal IgG on the developing infant brain.
• To determine the specific effects of maternal IgG on microglial cells and neuronal development.
• To elucidate the mechanisms by which maternal IgG influences neurodevelopment and behavior.

Main Methods:

• Detected maternal IgG immunoreactivity in pup brains, particularly in microglia within the corpus callosum and cerebellar white matter.
• Stimulated primary cultured microglia with IgG to analyze the type I interferon feedback loop activation via Syk.
• Utilized neonatal Fc receptor knockout (FcRn KO) mice to assess the consequences of impaired IgG uptake on brain development and behavior.

Main Results:

• Maternal IgG was found in microglia, peaking at one week postpartum, especially in white matter regions.
• IgG stimulation activated the Syk-mediated type I interferon feedback loop in cultured microglia.
• FcRn KO mice exhibited abnormal microglia, oligodendrocyte, and interneuron proliferation/survival, alongside social and locomotor deficits.

Conclusions:

• Maternal IgG plays a crucial role in normal brain development, influencing key cellular populations.
• Impaired maternal IgG transfer via FcRn knockout leads to significant neurodevelopmental and behavioral abnormalities.
• These findings highlight the critical impact of maternal-derived IgG on offspring brain maturation and function.