New research strengthens evidence that certain immune irregularities contribute to autism. The researchers found that mimicking a maternal infection in mice during pregnancy produced offspring with both lasting immune abnormalities and autism-like behaviors.

The study appears this week in the Proceedings of the National Academy of Sciences. The lead author is Elaine Hsiao, whose research is supported through her Autism Speaks Dennis Weatherstone Pre-Doctoral Fellowship grant. This fellowship program, established with a generous donation from the Stavros Niarchos Foundation, launches talented young scientists into the field of autism research.

Hsiao has been using mice to study how a mother’s infection during pregnancy may increase the risk of autism in her offspring, under the guidance of Paul Patterson, Ph.D., of the California Institute of Technology.

“We have long suspected that the immune system plays a role in the development of autism spectrum disorder,” says Dr. Patterson. Several studies of brain tissue  or blood samples have found links between autism and immune irregularities. In addition, several studies looking at large groups of women have linked increased risk of autism to maternal infection early in pregnancy. (Infections provoke inflammation, a strong immune response.) What remained unanswered was whether such immune changes contribute to the development of autism or stem from it.

For answers, Hsiao and her colleagues injected pregnant mice with a molecule that triggers inflammation similar to that produced by a viral infection. The offspring showed all three symptoms of autism – repetitive behaviors, decreased sociability and impaired communication.

The researchers also found immune abnormalities in the affected offspring. These included over-responsiveness in certain immune cells and decreases in other types of immune cells. These findings support those from previous studies in both animals and people.

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