Autism is a complex condition affecting brain development and is often linked to gastrointestinal issues. A new study now found that reducing the levels of an autism-linked gene in gut cells led to social deficits and brain signaling imbalances, but treatment with the probiotic Lactobacillus murinus improved social behavior and partially restored gut and brain function.

The findings, published in Cell Genomics, suggest that probiotics could help treat some forms of autism.

“A growing body of evidence underscores the broader neuroprotective effects of L. murinus, including its ability to mitigate depression, neuroinflammation, and stress-related disorders,” the researchers say. “Collectively, these studies emphasize the pivotal role of L. murinus in regulating brain function and behavior through gut microbiota-mediated pathways.”

Previous work has shown that many autism-linked genes are active in the gastrointestinal tract and gut bacteria can influence brain function through the ‘gut-brain axis’. However, the ways in which gut microbes could influence neuronal conditions are not yet fully understood.

Researchers led by Peifeng Ji at the Chinese Academy of Sciences in Beijing, China, used a mouse model of autism to investigate how disruptions in CHD8, a gene linked to the condition, affects both the gut and brain.

Brain function

In a previous study, the team found that mice with lower CHD8 levels in the brain showed autism-like behaviors, such as anxiety and learning difficulties. This time around, the researchers analyzed CHD8 mutant mice at a detailed cellular level and found disruptions in brain development.

The disruptions included altered gene expression, increased inflammation and higher levels of programmed cell death, particularly in the cerebral cortex — a brain region involved in cognition and memory. 

The researchers also found that CHD8 is crucial for gut development, as mice lacking it had excessive cell proliferation and immune system dysfunction, which impaired intestinal function.

Gut-brain axis

Mice that lacked CHD8 in gut cells also showed social difficulties and imbalances in brain signaling. However, treating the animals with L. murinus improved social behavior and partially restored gut and brain alterations, the team found.

Further experiments revealed that L. murinus influenced key neuronal pathways and reduced inflammation in both the gut and brain. This suggests that L. murinus can play a crucial role in regulating autism-related traits through the gut-brain axis — likely by interacting with the nervous system and reducing gut inflammation.

Although more research on the gut-brain axis is need to elucidate the exact mechanisms, the authors say, “[the] findings strongly support the role of L. murinus in modulating

the gut-brain axis and alleviating [autism]-related symptoms.”