A GABA-producing probiotic for the protection of CNS demyelinating inflammation

Abstract The gut-microbiota-brain axis has emerged as a critical pathway in the regulation of neuroinflammation. The gut microbiome regulates the severity of many experimental models of autoimmune central nervous system (CNS) demyelinating inflammatory diseases. Our most recent findings demonstrate that the microbiota of mice from different sources affects the severity of CNS inflammatory demyelination. Neuroinflammation triggered in experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis, modified the gut microbiota composition. The disease progression resulted in a significant reduction in the relative abundances of members of lactic acid bacteria when compared to healthy control mice. Among the altered taxa, bacteria producing gamma-aminobutyric acid (GABA) were significantly reduced. We hypothesized that modifying the microbiota with a probiotic while increasing intestinal GABA levels would reduce EAE’s severity. We genetically engineered a Lactococcus lactis probiotic that produces excessed levels of GABA. Real-time quantitative PCR analysis demonstrated an elevated expression of glutamic acid decarboxylase (GAD). GABA-specific ELISA showed a significant increase in neurotransmitter production when exposed to increasing concentrations of glutamic acid and time. In vivo, five times/week oral gavages with 5 × 108 CFU/mouse of GAD L. lactis but not with empty-plasmid carrier L. lactis protects against EAE in mice compared with sham-treated mice and prevents weight loss of animals while modulating the microbiome’s composition. Our results show that the increase of GABA at the intestinal level with the oral treatment with a probiotic strain protects against neuroinflammation in the CNS. Supported by grant from NIH (R15 NS107743)