Therapeutic Effects of the In Vitro Cultured Human Gut Microbiota as Transplants on Altering Gut Microbiota and Improving Symptoms Associated with Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a brain-based neurodevelopmental disorder characterized by behavioral abnormalities. Accumulating studies show that the gut microbiota plays a vital role in the pathogenesis of ASD, and gut microbiota transplantation (GMT) is a promising technique for the treatment of ASD. In clinical applications of GMT, it is challenging to obtain effective transplants because of the high costs of donor selection and heterogeneity of donors' gut microbiota, which can cause different clinical responses. In vitro batch culture is a fast, easy-to-operate, and repeatable method to culture gut microbiota. Thus, the present study investigates the feasibility of treating ASD with in vitro cultured gut microbiota as transplants. We cultured gut microbiota via the in vitro batch culture method and performed GMT in the maternal immune activation (MIA)-induced ASD mouse model with original donor microbiota and in vitro cultured microbiota. Open field, three-chamber social, marble burying, and self-grooming tests were used for behavioral improvement assessment. Serum levels of chemokines were detected. Microbial total DNA was extracted from mouse fecal samples, and 16S rDNA was sequenced using Illumina. Our results showed that GMT treatment with original and cultured donor gut microbiota significantly ameliorated anxiety-like and repetitive behaviors and improved serum levels of chemokines including GRO-alpha (CXCL1), MIP-1 alpha (CCL3), MCP-3 (CCL7), RANTES (CCL5), and Eotaxin (CCL11) in ASD mice. Meanwhile, the gut microbial communities of the two groups that received GMT treatment were changed compared with the ASD mice groups. In the group treated with in vitro cultured donor gut microbiota, there was a significant decrease in the relative abundance of key differential taxa, including S24-7, Clostridiaceae, Prevotella_other, and Candidatus Arthromitus. The relative abundance of these taxa reached close to the level of healthy mice. Prevotella_other also decreased in the group treated with original donor gut microbiota, with a significant increase in Ruminococcaceae and Oscillospira. The present study demonstrated that GMT with in vitro cultured microbiota also improved behavioral abnormalities and chemokine disorders in an ASD mouse model compared with GMT with original donor gut microbiota. In addition, it significantly modified several key differential taxa in gut microbial composition.