Gut microbiota and brain-resident CD4T cells shape behavioral outcomes in autism spectrum disorder.

Scientists studied how gut bacteria might affect autism behaviors using mice. They found that mice without gut bacteria had fewer autism-like behaviors and less brain inflammation. A specific probiotic (good bacteria) called Limosilactobacillus reuteri IMB015 helped improve behaviors by reducing brain inflammation and balancing brain chemicals. This suggests gut health might influence autism symptoms through the immune system.

This preclinical study using BTBR mice investigated the gut-brain connection in autism spectrum disorder. Researchers found that removing gut bacteria (germ-free conditions) improved autism-like behaviors and reduced brain inflammation. The study identified that CD4 T cells and specific bacterial metabolites, particularly those affecting glutamate/GABA balance, play key roles in autism behaviors. A specific probiotic strain, Limosilactobacillus reuteri IMB015, showed promise in reducing neuroinflammation and improving behaviors by normalizing glutamate/GABA ratios.

The research proposes a gut-immune-brain axis where gut microbiota influences brain-resident immune cells, which in turn affect autism-associated behaviors including social, repetitive, and anxiety-like symptoms.

While promising, this preclinical research requires human clinical trials before therapeutic applications. The gut-immune-brain axis findings suggest potential for microbiome-based interventions, but safety and efficacy in humans remain unestablished. Current autism treatments should continue as recommended by healthcare providers.

This is a preclinical mouse study using the BTBR autism model. Sample sizes not reported. Findings may not translate directly to humans. The study focuses on male mice only, limiting generalizability to females.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by alterations in social, repetitive, and anxiety-like behaviors. While emerging evidence suggest a gut-brain etiology in ASD, the underlying mechanisms remain unclear. To dissect this axis, we developed a germ-free BTBR mouse model for ASD. The absence of gut microbiota in male mice ameliorates ASD-associated behaviors and reduces populations of inflammatory brain-resident T cells.

Additionally, CD4T cell depletion mitigates neuroinflammation and ASD behaviors, suggesting a gut-immune-brain axis. We identify several microbial and metabolic regulators of ASD, particularly those relevant to the glutamate/GABA ratio and 3-hydroxyglutaric acid. Using an in silico metabolite prediction model, we propose Limosilactobacillus reuteri IMB015 (IMB015) to be a probiotic candidate. Administration of IMB015 reduces the glutamate/GABA ratio and neuroinflammation, resulting in improved behaviors.

Here we report a gut-immune-brain axis in which the gut microbiota and its metabolites can modulate brain-resident immune cells and ASD-associated behaviors.