Oral Microbiota Changes Contribute to Autism Spectrum Disorder in Mice

The oral microbiota has been implicated in various neurologic conditions, including autism spectrum disorder (ASD), a category of neurodevelopmental disorders defined by core behavioral impairments. Recent data propose the etiopathogenetic role of intestinal microbiota in ASD. The aim of the present study was to elucidate whether the oral microbiota contributes to the pathogenesis of ASD. On the basis of microbial changes detected in the oral cavity of children with ASD, we transferred oral microbiota from donors with ASD and typical development (TD) into an antibiotic-mediated microbiota-depleted mouse model and found that the ASD microbiota is sufficient to induce ASD-like behaviors, such as impaired social behavior. Mice receiving oral microbiota from the ASD donor showed significantly different microbiota structures in their oral cavity and intestinal tract as compared with those receiving TD microbiota and those not receiving any bacterium. The prefrontal cortex of ASD microbiota recipient mice displayed an alternative transcriptional profile with significant upregulation of serotonin-related gene expression, neuroactive ligand-receptor interaction, and TGF-β signaling pathway relative to that in TD microbiota recipient mice. The expression of serotonin-related genes was significantly increased in ASD microbiota recipient mice and was associated with selective autistic behaviors and changes in abundance of specific oral microbiota, including species of Bacteroidetes [G-7], Porphyromonas, and Tannerella. Machine learning based on the causal inference method confirmed a contributing role of Porphyromonas sp. HMT 930 in ASD. Taken together, the oral microbiota of children with ASD can lead to ASD-like behaviors, differences in microbial community structures, and altered neurosignaling activities in recipient mice; this highlights the mouth-microbial-brain connections in the development of neuropathology and provides a novel strategy to fully understand the etiologic mechanism of ASD.