Neuroprotective effects of Bifidobacterium animalis HN019 and Lactobacillus acidophilus NCFM in MPTP-induced Parkinson's disease mice.

Several studies have demonstrated that modulation of the gut microbiota represents a promising strategy to alleviate symptoms of Parkinson's disease (PD). Our previous study revealed a depletion of Lactobacillus species in patients with PD and an association between Bifidobacterium abundance and improvement in non-motor symptoms. Lactobacillus acidophilus NCFM and Bifidobacterium animalis subsp. lactis HN019 are two well-characterised probiotic strains. In the present study, a probiotic cocktail containing these two strains exhibited protective effects on both the gastrointestinal tract and the substantia nigra (SN) in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model. Oral supplementation with the probiotics alleviated motor and non-motor dysfunctions in the PD mouse model. Furthermore, α-synuclein (α-Syn) overexpression was reduced in both the colon and SN. Inflammatory factors and the toll-like receptor 2/toll-like receptor 4-nuclear factor κ-light-chain-enhancer of activated B cells (TLR2/TLR4-NF-κB) signalling pathway in the colon and brain were downregulated following probiotic treatment. Alterations in the gut microbiota were further examined to identify potential regulatory factors of inflammation. The relative abundances of propionate- and butyrate-producing bacteria, their biosynthetic pathways, and the critical enzymes were all elevated in the gut microbiota of probiotic-treated mice. These findings suggest that the probiotic cocktail exerts strong anti-inflammatory effects in both the colon and SN by enhancing microbial production of propionate and butyrate and suppressing activation of the TLR2/TLR4-NF-κB pathway.