Rhodopseudomonas pseudopalustris Mitigates Alzheimer’s Disease-Related Pathology in C. elegans Models by Enhancing Antioxidant Defense Capacity and Immune Activity

Alzheimer’s disease (AD) lacks effective disease-modifying therapeutics. Probiotics, promising neuroprotective candidates, exert benefits mainly by modulating gut-brain-axis (GBA) signaling. This study explored the anti-AD effects and mechanisms of Rhodopseudomonas pseudopalustris (R. pse). Using Caenorhabditis elegans (C. elegans) AD models, we evaluated AD-related phenotypes (learning deficits, paralysis) after R. pse administration, and performed genetic analysis and metabolomic profiling to clarify its regulatory pathways and metabolites. Mechanistically, R. pse significantly alleviated AD-related phenotype in C. elegans. It upregulated γ-glutamylcysteine synthetase (GCS-1) to enhance the glutathione (GSH)-dependent antioxidant defense. Knockout of the oxidation repair enzyme methionine sulfoxide reductase A-1 (MSRA-1) abolished the neuroprotective effects of R. pse, which was rescued by methionine. R. pse also activated activating transcription factor 7 (ATF-7)-mediated innate immunity and transforming growth factor β (TGF-β) signaling, with pantothenic acid as its functional metabolite. Collectively, R. pse is a potential anti-AD bacterium that mitigates AD model pathogenesis by enhancing the cellular antioxidant capacity, providing experimental evidence for bacteria-based AD interventions.