A quarterly publication of the Autism Research Institute

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

Summer, 2022 | Number 3, Volume 36

Mouse study offers more clues about the possible role of gut microbes in ASD

A study from researchers in Italy and Switzerland adds to evidence that gut microbes play a role in autism spectrum disorders (ASD). 

In the experiment, Ennio Avolio and colleagues studied three groups of mice. Six of the mice received fecal microbiota transplants from children with ASD, while another six mice were exposed to the anticonvulsant valproic acid (VPA) during gestation. (VPA is known to produce autistic-like symptoms in mice; thus, mice exposed to this drug in utero are considered a mouse model for autism.) A third group of mice were treated with fecal transplants from children without ASD and served as controls. 

The researchers say that both VPA-exposed mice and mice that received fecal transplants from children with ASD exhibited autistic-like behaviors when tested. In addition, both groups exhibited alterations of gut bacteria compared to the control mice. In particular, both groups had higher populations of Tenericutes and lower levels of Candidatus S. and Actinobacteria. Both groups of mice also exhibited atrophy of the intestinal villi (the finger-like projections that line the small intestine) and infiltration of inflammatory cells in the small intestine, and the mice that received fecal transplants from children with ASD exhibited increases in several pro-inflammatory factors in the brain and small intestine. Finally, the two treated groups exhibited altered methylation—the mechanism in which genes are turned “on” or “off”— in the brain, and the mice who received the fecal transplants from children with ASD also exhibited reduced methylation activity in the bowel. 

“Overall,” the researchers say, “findings of the present study corroborate a key role of gut microbiota in ASD.” This suggests, they say, that the gut microbiome could be a target for treatment. “However,” they say, “further investigations are required before any possible manipulation of gut bacteria with appropriate diets or probiotics can be conducted in ASD individuals.”


Citations

“Modifications of behavior and inflammation in mice following transplant with fecal microbiota from children with autism,” Ennio Avolio, Ilaria Olivito, Eleonora Rosina, Lorenzo Romano, Tommaso Angelone, Anna De Bartolo, Manuel Scimeca, Dina Bellizzi, Patrizia D’Aquila, Giuseppe Passarino, Raffaella Alò, Rosa Maria Facciolo, Claudia Bagni, Antonino De Lorenzo, and Marcello Canonaco, Neuroscience, August 21, 2022, pp. 174-189. Address: Marcello Canonaco, Laboratory of Comparative Neuroanatomy, Department of Biology, Ecology and Earth Science (DiBEST), University of Calabria, Cosenza, Italy, [email protected].