Overactive immunity in pregnancy linked to brain damage in offspring

The male child may be more vulnerable to brain disorders due to the immune system 'overdrive' in pregnant women than the female child -- and the impact may be life long, a new study shows.

The hippocampus - part of the brain responsible for memory and spatial navigation - was found smaller over the long term in male offspring exposed to the overactive immune system in the womb, said researchers.

In research conducted on male mice, scientists found that the males also had fewer nerve cells in their brains and their brains contained a type of immune cell that should not be present there.

"Now we wonder if this could explain why more males have diseases such as autism and schizophrenia which appear to have neurobiological causes," said study leader Irina Burd, assistant professor of gynecology/obstetrics and neurology at Maryland-based Johns Hopkins University's school of medicine.

Fetal male mice show signs of brain damage that lasts into their adulthood when they are exposed in the womb to a maternal immune system kicked into high gear by a serious infection or other malady.

For the study, researchers sought to mimic the effects of a maternal infection or other condition that causes inflammation in a pregnant mother.

Burd and colleagues used a mouse model to study what happens to the brains of those offspring as they age into adulthood to see if the effects persisted.

The sex-specific differences -- the smaller hippocampus, the presence of fewer nerve cells and the existence of immune system macrophages in places they shouldn't be -- were also found in adulthood.

Chronic inflammation may play a role in keeping the hippocampus small, potentially because it inhibits proper brain development.

Unravelling the sex-based mechanisms underlying the response to maternal inflammation could provide critical knowledge to develop new drug therapies, said the report published in the journal Brain, Behaviour and Immunity.