Exposing newborn neurons to higher than normal levels of a common immune protein results in abnormal brain development in mice studies, according to scientists from the University of California.
The discovery provides fresh insight into factors leading to human neurological disorders such as autism and schizophrenia.
The research team observed a protein called major histocompatibility complex, or MHC. This protein plays a double role in the body. It alerts the immune system to infected cells, and it helps neurons make the right connections with one another in the brain.
“When neurons sense infection or damage to the brain, they produce more MHC,” said Daniel Kaufman, professor of molecular and medical pharmacology at the David Geffen School of Medicine at UCLA.
“We wanted to explore whether higher levels of MHC affect how the brain develops.”
Kaufman and his team studied the development of mice whose neurons were genetically engineered to produce higher-than-average levels of MHC.
Honing in on two key areas of the brain, the scientists focused on neurons that process vision as well as neurons associated with learning and memory. Then the researchers compared these cells with their counterparts in normal mice.
The results confirmed their initial ideas.
“The mice whose neurons produced extra MHC showed subtle changes in the connections between those neurons and other neurons in both brain regions,” Kaufman said.
He noted that these findings could be of relevance in unraveling the origins of schizophrenia and autism.
“Infections in pregnant women have been associated with slightly higher risks for schizophrenia and autism in their children,” he said. “Subtle changes in brain development due to excess MHC may explain this relationship.”
Kaufman added that female mice that develop infections during pregnancy also often have babies with behavioral abnormalities similar to autism and schizophrenia.
“We suspect that infection stimulates the mother’s immune system to produce molecules that act like distress signals — they circulate through her blood and then enter the developing brain of the fetus,” he said.
“There, they alert neurons to make more MHC, which our study shows can lead to altered neuronal circuitry.”
“This finding gives us greater insight into the role that MHC plays in the nervous system and may enhance our understanding of the factors that can contribute to neuropsychiatric disorders like autism and schizophrenia,” Kaufman said.
This study is published in the online Journal of Neuroimmunology.
Source: University of California