In recent years, a growing body of research has highlighted the important role the gut microbiome plays in human health.
It has been linked not only to digestion, but also to fear responses, weight, mental health, and the risk of autoimmune conditions such as lupus and type 1 diabetes, suggesting it may influence multiple systems in the body.
A new study published in The Journal of Immunology has now explored a possible connection between the gut microbiome and autism using animal models. However, researchers found that it is not the individual’s own microbiome, but the mother’s, that may play a key role in early development.
Lead researcher John Lukens of the University of Virginia School of Medicine explained that the microbiome can shape the developing brain in several ways, particularly by helping determine how an offspring’s immune system responds to infection, injury, or stress.
A central factor in the study is a molecule called interleukin-17a (IL-17a), produced by the immune system. It has already been associated with autoimmune conditions such as rheumatoid arthritis, multiple sclerosis, and psoriasis, and is known to help fight infections while also influencing brain development during pregnancy.
In the experiments, researchers blocked IL-17a in mice. The animals came from two different laboratory groups: one with a gut microbiome that triggered an IL-17a-related inflammatory response, and a control group that did not.
When IL-17a was blocked in the first group, preventing inflammation, their offspring developed typical behaviours. But when left unchanged, the pups born to these mothers showed autism-like traits, including social difficulties and repetitive behaviours.
To further test the link, researchers performed a fecal transplant, transferring gut bacteria from the first group into the control group. The offspring of these mice also began to show similar neurodevelopmental changes, reinforcing the role of the microbiome in the outcome.
While the findings suggest a strong connection between maternal gut health and neurodevelopment, researchers stress that the work is still at an early stage and may not directly apply to human pregnancy.
The next step, Lukens said, is to investigate whether similar patterns exist in humans and to identify which specific elements of the maternal microbiome may be involved. He also noted that IL-17a may represent only one part of a far more complex biological process.
Overall, the study adds to growing evidence that the maternal microbiome could play an important role in early brain development, opening new directions for future autism research and potential therapeutic approaches.