Viral infection in mothers may cause the development of disrupted foetal immune system in babies which may lead to certain neurodevelopmental disorders in later life, a study has found.
The findings showed that the mother’s infection with the cytomegalovirus (CMV) during pregnancy may affect her own as well as her babies’ immune system and thus increase the risk of the offspring developing autism or schizophrenia.
“Previous studies had shown that the timing of the disruption in the mother’s immune system during pregnancy affects the type of brain damage her child may develop,” said lead researcher Ido Amit from Weizmann Institute of Science — a public research university in Israel.
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A viral infection in early pregnancy raises the risk of autism, whereas an infection later in the pregnancy raises the risk of schizophrenia, said the paper in the journal published in Science.
Further, the pre-development of stages of microglia — sole immune cells present in the brain — cells in the mouse foetus and in newborn mice proved the most sensitive to disruptions.
The heightened immune response to viral infection in the mother’s body may be responsible for disrupting the timing of microglia development, the researchers said.
“We’ve discovered that it’s essential for the development of immune cells in the brain to be synchronised with the development of the brain itself. Premature shift of the microglia in mice to the adult stage leads to brain malfunction later on,” added Michal Schwartz, Professor at Weizmann Institute of Science.
For the study, the scientists exposed the brains of pregnant mice to synthetic materials that mimic a CMV infection.
They found that the development of the pre-microglia was disrupted in their offspring.
Genes involved in the maturation of these cells were expressed at the wrong time and the cells proceeded to an adult stage earlier than usual, leading to the offspring later exhibiting abnormal behaviour, including disturbances in social interaction and behaviours similar to those of people with schizophrenia.
In addition, the team found that the maturation of the microglia was delayed in newborn mice who were free of any intestinal microbes — the microbiome.
In human babies, factors that shape the microbiome – natural ones such as breastfeeding, or therapeutic, such as antibiotics — may affect the immune cells in the baby’s brain and consequently the brain’s development, the researchers suggested.