Behavioral and biological alterations following transplantation of ASD-associated gut microbiota in mice.

Background: Alterations in the gut microbiota have been increasingly reported in individuals with autism spectrum disorder (ASD). However, the extent to which ASD-associated microbial communities are linked to behavioral and host biological changes remains to be clarified. Methods: Fecal microbiota transplantation (FMT) was performed using samples from children with ASD or typically developing (TD) controls into antibiotic-pretreated mice. Behavioral performance was evaluated using open field, social interaction, and spatial learning paradigms. Gut microbial composition was assessed by 16S rRNA gene sequencing. Peripheral immune-related parameters were assessed, including circulating regulatory T cells and serum cytokine profiles. Histological and molecular analyses were conducted in the terminal ileum and hippocampus, including immunohistochemistry, Western blotting, exploratory brain proteomics, and targeted qRT-PCR validation. Results: Mice receiving ASD-associated microbiota displayed altered behavioral performance, including reduced sociability and impaired spatial learning. 16S rRNA sequencing revealed distinct gut microbial profiles between ASD-FMT and TD-FMT groups, with increased abundance of Enterobacteriaceae and related taxa in ASD-FMT mice. Peripheral analysis showed reduced regulatory T cell levels and altered serum cytokine profiles. Histological examination identified changes in intestinal architecture and increased expression of glial markers in the hippocampus. Proteomic analysis indicated differential expression of proteins enriched in pathways related to neural structural organization and metabolic processes. Conclusions: These findings indicate that gut microbiota derived from children with ASD is associated with coordinated behavioral, peripheral immune-related, and brain histological changes in mice. This study provides integrative evidence supporting associations between ASD-associated microbial features and coordinated behavioral and biological alterations in the host.