By: Erin Thomas

A new study by researchers at the UC Davis Center for
Neuroscience and Department of Neurology found that viral infection during
pregnancy may cause a higher chance of autism onset as well as schizophrenia.
This is the first evidence that levels of major histocompatibility complex
class I molecules (MHC1), cells involved in regulating immunity, are altered on
the surface of neurons in an offspring’s brain if the mother’s immune system is
activated. The study showed that MHC1 levels are doubled on the surface of
neurons in the newborn offspring of mothers whose immune systems are activated.
This suggests that MHC1 levels are very responsive to a peripheral immune
response in the mother (Elmer, 2013). This is significant because maternal
immune activation is a risk factor for Autism Spectrum Disorders and
schizophrenia in humans. Mouse models have shown that offspring of mothers
with immune activation show symptoms of both ASD and schizophrenia. This study
demonstrated that maternal immune activation causes MHC1 signaling to limit the
capability of neurons to form synapses, which are connections between neurons. When MHC1 levels in the newborns were
made to return to normal, synaptic densities also returned to normal levels. Future
experiments will seek to determine how the MHC1 signaling pathway is
specifically affected by maternal immune activation.

B. M. Elmer, M. L.
Estes, S. L. Barrow, A. K. McAllister. MHCI
Requires MEF2 Transcription Factors to Negatively Regulate Synapse Density
during Development and in Disease. Journal of Neuroscience,
2013; 33 (34): 13791 DOI:10.1523/%u200BJNEUROSCI.2366-13.2013

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