In recent years, scientists have increasingly uncovered how deeply our gut microbiome, the trillions of bacteria living in our digestive tract, impacts our overall health. From mental well-being and stress response to autoimmune diseases like rheumatoid arthritis and type 1 diabetes, the influence of gut flora appears to be far-reaching.
A new study published in The Journal of Immunology sheds light on a possible connection between gut bacteria and the development of autism spectrum disorder (ASD). The research focuses on a molecule called interleukin-17a (IL-17a), a chemical produced by the immune system that may influence how the brain develops in the womb.
According to the World Health Organization, autism is a group of diverse neurodevelopmental conditions that affect social interaction and communication. Many individuals with autism also live with co-occurring conditions such as epilepsy, anxiety, ADHD, sleep challenges, and sometimes self-injurious behavior. Intellectual abilities vary widely among those on the spectrum.
The Role of Maternal Microbiome
Researchers from the University of Virginia School of Medicine suggest that a child’s risk of developing autism may be more closely tied to the mother’s gut microbiota than their own.
“The microbiome can shape the developing brain in multiple ways,” said John Lukens, lead author and PhD researcher.
“It’s really important to how the offspring’s immune system calibrates itself to respond to infections, injuries, or stress.”
The molecule IL-17a, long known for its role in inflammatory diseases such as psoriasis, multiple sclerosis, and rheumatoid arthritis, also plays a surprising role in fetal brain development.
Testing the Theory on Mice
To explore this, scientists conducted an experiment on mice with differing gut bacteria profiles. One group carried microbiota known to stimulate strong IL-17a production, while the control group did not.
When researchers temporarily blocked IL-17a in the pups, both groups showed neurotypical behavior. However, once that suppression ended and the mice matured naturally, the first group began displaying autism-like traits, such as repetitive behaviors.
To take it a step further, scientists then performed a fecal transplant, transferring the gut bacteria from the autism-prone mice to the control group. The second group soon developed similar autism-like behaviors, suggesting that pro-inflammatory bacteria in the maternal gut could play a critical role.
Implications and Cautions
Though this research was conducted solely on mice, it opens the door to further study of how a mother’s gut health might influence the risk of neurodevelopmental disorders in children.
“In terms of translating our work to humans, I think the next big step would be to identify features of the microbiome in pregnant mothers that correlate with autism risk,” Lukens said.
“From there, the goal would be to safely modulate the maternal microbiome.”
While targeting IL-17a might seem like a potential path for preventing autism, Lukens warns of the risks. Pregnancy requires a finely tuned immune balance, as the mother’s body is supporting what it sees as foreign tissue, the baby. Disrupting that balance could pose serious risks to both mother and fetus.
Instead, researchers are now looking into other molecular players within this complex system. IL-17a is just one piece of a much larger puzzle, and future discoveries may help us understand how gut health in pregnancy could influence the next generation’s neurological development.
