Lacticaseibacillus rhamnosus GR-1 prevents autism-like behaviors by reshaping the maternal and offspring microbiome

As a prevalent neurodevelopmental disease, whether ASD (autism spectrum disorder) can be ameliorated by the early use of a single microbe remains unknown. Here we used a lactobacillus strain, Lacticaseibacillus rhamnosus GR-1 (LGR-1), for prenatal intervention in autism-like mice with either environmental or idiopathic origins by exclusively administering to the pregnant dams at a dose of 10⁹/mouse/day, followed by offspring behavioral assessment with 3-chamber trial and marble burying test. The results revealed that LGR-1 prevented the occurrence of autism-like symptoms, as evidenced by the improved behaviors and restored E/I (excitatory-inhibitory) balance in the prefrontal cortex of male pups. In parallel, the offspring microbiome was reshaped by LGR-1 treatment, probably mediated by the vertical transmission of maternal microbiome, with its roles further unraveled by fecal microbiota transplant and cross-fostering experiments. In addition to gut commensals, the LGR-1-shaping vaginal microbiota also contributed to the establishment of "beneficial" microbiome. Regarding key taxa in offspring, Akkermansia muciniphila was influenced by LGR-1 and exerted impact on behaviors via pathways related to IL-17-producing lymphocytes. Our findings demonstrate that prenatal microbial administration protects offspring against autism-like behavioral phenotypes through microbiome transmission, highlighting a potential microbe-based therapeutic avenue to mitigate ASD risk.