Changes in tongue-coating microbiota and its predictive role in treatment outcomes following washed microbiota transplantation in children with autism

Significant changes are noted in the oral and gut microbiota of children with autism spectrum disorder (ASD). However, the correlation and interaction between these microbiota and their roles in predicting the outcomes of fecal microbiota transplantation (FMT) in ASD children are still not well understood. In this study, we report considerable changes in the structure and function of the tongue-coating microbiota in ASD children, identifying various bacteria that correlate with ASD symptoms and gut microbiota. Additionally, both germ-free ASD mice that received healthy gut microbiota and ASD children treated with washed microbiota transplantation (WMT) showed significant improvements in autism symptoms, along with marked changes in their gut and tongue-coating microbiota. Notably, we observed a significant decrease in the abundance of tongue-coating Haemophilus, which positively correlates with ASD severity, and a reduction in enhanced chemoheterotrophy and fermentation functions in the tongue-coating microbiota of ASD children after WMT. Furthermore, predictive models developed using pre-treatment tongue-coating microbiota and clinical symptoms effectively predicted the outcomes of WMT treatment, demonstrating predictive accuracy on par with models based on gut microbiota. These findings indicate that there is a significant interaction between the gut and tongue-coating microbiota in ASD, an interaction that could play a crucial role in the treatment of ASD. Predictive models based on pre-treatment tongue-coating microbiota and clinical features can promote precision treatment for children with ASD undergoing WMT.