A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Winter, 2019 | Number 1, Volume 33

Simple microbe therapy may improve social behavior in autism

A study conducted by a team of researchers at Baylor University suggests that administering a specific strain of gut microbes to individuals with autism may help ameliorate their social deficits.

Study coauthor Mauro Costa-Mattioli says, “In 2016, we discovered in mice that the offspring of mothers fed a high-fat diet had social deficits and changes in their gut microbiome were characterized by a reduction in the abundance of the bacterial species L. reuteri. More importantly, restoring L. reuteri levels in the offspring reversed their social deficits. This model of ASD represents only one of the numerous heterogeneous underpinnings of the condition. Therefore, we decided to investigate whether our findings would apply to other models with different origins.”

When the researchers tested the effects of L. reuteri on a range of mouse models, they found that the microbe reversed social deficits in all models tested—whether the autism was environmentally caused, genetically caused, or idiopathic (meaning that the cause was unknown). The researchers also found that the effects of L. reuteri did not result from changes to the composition of the gut microbiome, which was altered in all of the models tested. Instead, study coauthor Martina Sgritta says, “We discovered that L. reuteri promotes social behavior via the vagus nerve, a nerve that bidirectionally connects the gut and the brain and the oxytocin-dopamine reward system.” Activation of this nerve stimulates neurons that produce oxytocin, a hormone that promotes social bonding.

“Interestingly,” Sgritta says, “we found that when the vagus nerve was severed, and the brain-gut connection was disrupted, L. reuteri could no longer restore social behavior in ASD mice. In addition, when we genetically engineered mice to lack oxytocin receptors in reward neurons or blocked the receptors with specific drugs, the treatment with L. reuteri also failed to reverse the social deficits in the ASD mice.”

The researchers emphasize that their findings are preliminary and that the effects of L. reuteri need to be tested in clinical trials on humans. However, they conclude, “Treatment with L. reuteri emerges as a promising non-invasive microbial-based avenue to combat ASD-related social dysfunction.”


Citations

“Mechanisms underlying microbial-mediated changes in social behavior in mouse models of autism spectrum disorder,” Martina Sgritta, Sean W. Dooling, Shelly A. Buffington, Eric N. Momin, Michael B. Francis, Robert A. Britton, and Mauro Costa-Mattioli, Cell, December 3, 2018 (online). Address: Mauro Costa-Mattioli, [email protected].

—and—

“The power of the microbiome: A microbebased treatment reverses social deficits in mouse models of autism,” From the Labs, Baylor College of Medicine, December 13, 2018.

—and—

“Can autism be treated with a simple microbial-based therapy?”, ScienceBlog.com, December 21, 2018.