In recent years, scientists have increasingly recognized the powerful connection between gut health and overall well-being. From mental health and stress response to autoimmune conditions like rheumatoid arthritis and type 1 diabetes, the influence of gut bacteria—also known as the microbiota—extends across many aspects of human biology.
Now, a new study published in The Journal of Immunology offers fresh insight into a potential link between the microbiome and autism spectrum disorder (ASD).
Autism and Co-Occurring Conditions
According to the World Health Organization (WHO), autism is a group of complex neurodevelopmental conditions that affect communication, social interaction, and behavior. Individuals with autism often experience co-occurring challenges such as epilepsy, anxiety, depression, ADHD, sleep disturbances, and self-injury. Intellectual ability among individuals with autism varies widely.
The Role of Maternal Microbiota
The study, led by John Lukens, Ph.D., from the University of Virginia School of Medicine, suggests that a child’s risk of developing autism may be more influenced by the mother’s gut microbiota than their own.
“The microbiome can shape the developing brain in multiple ways,” Lukens explained. “It’s crucial in determining how a child’s immune system will respond to infection, injury, or stress.”
A key player in this process appears to be interleukin-17a (IL-17a), a molecule produced by the immune system. IL-17a is known to play a role in autoimmune diseases like psoriasis, multiple sclerosis, and rheumatoid arthritis, as well as in defending the body against fungal infections. Recent evidence also suggests it could affect brain development during pregnancy.
Experimenting With Gut Bacteria and Behavior
To explore this link, scientists conducted a study using mice with different types of gut bacteria. One group had microbiota associated with stronger inflammatory responses triggered by IL-17a, while the control group did not. Initially, researchers suppressed IL-17a in both groups, and all the mice displayed typical behavior. However, once the suppression stopped and the mice developed naturally, those from the high-inflammatory group began exhibiting autism-like behaviors such as repetitive actions.
In a second experiment, fecal matter from the first group was transplanted into the second group, effectively transferring the pro-inflammatory gut bacteria. After the transplant, the second group of mice also developed behaviors associated with autism.
A Path Toward Future Research
Though these findings are limited to animal studies, they lay important groundwork for future research into the role of maternal gut health in neurodevelopmental disorders.
“The next step is to identify specific features of the microbiome in pregnant women that correlate with autism risk,” said Lukens. “Eventually, we want to find safe and effective ways to modify the maternal microbiome to reduce this risk.”
Caution Around Immune Interventions
While blocking IL-17a could be a possible intervention, Lukens cautions against manipulating the immune system during pregnancy. “Pregnancy involves the immune system tolerating what is essentially foreign tissue—the baby,” he noted. “Maintaining embryonic health requires a delicate immune balance, so any interference carries risks.”
He emphasized that IL-17a is only one piece of a much larger puzzle and that many other biological factors remain to be explored.
