A neuroprotective effect of newly isolated probiotic bacterium Lactobacillus acidophilus SLAM_LAA02 in a rotenone-induced mouse model of Parkinson’s disease

The gut microbiota plays a pivotal role in maintaining host health and has increasingly been linked to the pathogenesis of neurodegenerative diseases through the microbiota-gut-brain axis. Parkinson's disease (PD), characterized by dopaminergic dysfunction, neuro inflammation, and pathological alpha-synuclein (α-synuclein) aggregation, is frequently accompanied by gut microbial dysbiosis. Probiotics isolated from human infants could offer distinct neuroprotective and immunomodulatory benefits, yet their effects on integrated gut-brain axis models remain underexplored. In this study, we investigated the therapeutic potential of Lactobacillus acidophilus SLAM_LAA02 (L. acidophilus SLAM_LAA02), a novel infant-derived strain, in modulating PD-related behavioral and neuropathological features via modulation of the gut-brain axis. Following comprehensive safety and functional assessments, we first assessed L. acidophilus SLAM_LAA02 in Caenorhabditis elegans, where supplementation extended lifespan, enhanced antimicrobial defense, improved behavioral responses, and reduced α-synuclein expression in transgenic worms. We then evaluated its effects in a rotenone-induced mouse model that reflects early-stage PD-like features. L. acidophilus SLAM_LAA02 administration ameliorated motor dysfunction, modulated neuroinflammatory signaling, restored gut microbial diversity, and improved intestinal barrier-associated outcomes. These changes were accompanied by a notable reduction in α-synuclein expression and upregulated neuroprotective gene expression, including brain-derived neurotrophic factor (BDNF). Together, these findings suggest that L. acidophilus SLAM_LAA02 exhibits neuroprotective and gut-modulating properties across complementary model systems, supporting its potential as a promising probiotic candidate for alleviating early PD-related dysfunctions through the gut-brain axis.