Microbiota-related Changes in Bile Acid & Tryptophan Metabolism are Associated with Gastrointestinal Dysfunction in a Mouse Model of Autism

Autism spectrum disorder (ASD) is one of the most prevalent neurodevelopmental conditions worldwide. There is growing awareness that ASD is highly comorbid with gastrointestinal distress and altered intestinal microbiome, and that host-microbiome interactions may contribute to the disease symptoms. However, the paucity of knowledge on gut-brain axis signaling in autism constitutes an obstacle to the development of precision microbiota-based therapeutics in ASD. To this end, we explored the interactions between intestinal microbiota, gut physiology and social behavior in a BTBR T+Itpr3tf/J mouse model of ASD. Here we show that a reduction in the relative abundance of very particular bacterial taxa in the BTBR gut – namely, bile-metabolizing Bifidobacterium and Blautia species, - is associated with deficient bile acid and tryptophan metabolism in the intestine, marked gastrointestinal dysfunction, as well as impaired social interactions in BTBR mice. Together these data support the concept of targeted manipulation of the gut microbiota for reversing gastrointestinal and behavioral symptomatology in ASD, and offer specific plausible targets in this endeavor.
Highlights • BTBR mice display a reduced abundance of bile-metabolizing Bifidobacterium and Blautia bacterial species in the intestine. • BTBR mice demonstrate deficient bacterial metabolism of bile moieties in the gut. • Changes in the gut microbiota are associated with marked gastrointestinal distress and reduced sociability in BTBR mice. There is growing awareness that the gut microbiome may contribute to gastrointestinal and behavioral symptomatology of autism spectrum disorder (ASD). However, the exact mechanisms by which intestinal bacteria can affect gut-brain axis signaling in autism are as yet poorly understood. Here we explore interactions between intestinal microbiota, gut physiology and behavior in a mouse model of ASD. We show that a reduction in the abundance of particular intestinal bacteria in “autistic” mice is associated with gastrointestinal distress and social behavior deficits. This work supports the concept of targeting the gut microbiota for reversing gastrointestinal symptoms in ASD, and identifies specific plausible targets for microbiota-based interventions.