Possible Connection Between Gastrointestinal Inflammation and Autism Disorders Identified

Harvard Medical School and MIT researchers may have found a connection between gastrointestinal inflammation and autism spectrum disorders. Their findings were published in Immunity.

The research team first confirmed that maternal immune activation (MIA) leads to enhanced susceptibility to intestinal inflammation in offspring by injecting pregnant mice with poly(I:C), a substance that mimics viral infection. Their offspring, but not the offspring of mothers in an unaffected control group, exhibited autism-like symptoms, as expected, and also gut inflammation when exposed to other inflammatory stimuli.

While the neurodevelopmental aberrations the team has tracked occur while the fetus is still in the womb, it was not clear when the altered immune responses developed. To find out, the team switched mouse pups at birth so that ones born to MIA moms were reared by control moms and ones born to control moms were reared by MIA moms. The results showed that while neurodevelopment is altered before birth, the immune response is altered postnatally.

Then to determine whether these differences played a causal role, they raised a new set of female mice in a germ-free environment and transplanted stool from MIA or control moms into these germ-free moms and bred them with males. Unlike the controls, pups born to MIA-stool-transferred moms exhibited intestinal inflammation. These results indicated that the altered microbiome of MIA moms leads to the immune priming of offspring. Among the notable differences, the team measured the intestinal inflammation response was an increase in IL-17a production by immune system T cells.

The researchers say that the results highlight that environmental exposures during pregnancy, such as infection, can have long-term health consequences for offspring.