Probiotics Attenuate AlCl₃-Induced Alzheimer's Disease via Gut-Brain Axis Modulation and Suppression of NF-κB/NLRP3 Neuroinflammation

Disruptions along the brain-gut-microbiota axis significantly contribute to Alzheimer's disease (AD) pathogenesis. This study evaluated the therapeutic potential of a multi-strain probiotic mixture in mitigating cognitive decline, neuroinflammation, and amyloid pathology in an AD rat model. In the present study, after induction of AD in rats by oral administration of AlCl₃ (50 mg/kg) for 28 days, followed by oral treatment with a probiotic mixture (10⁹ log CFU/ml) for 42 days. Behavioral assessments were conducted during the final week. Hippocampal tissues were obtained for histopathological and gene expression analyses and fecal samples were subjected to full-length 16S rRNA gene sequencing via Oxford Nanopore approach. Probiotics significantly improved AD-induced deficits in locomotor activity, exploratory behavior, and spatial recognition memory. Histological analysis revealed marked reductions in hippocampal β-amyloid deposition and substantial restoration of colonic mucosal barrier integrity. Microbiota profiling showed that probiotics reversed dysbiosis, significantly enriching beneficial genera (Blautia, Clostridium, Eubacterium). Blautia abundance was strongly negatively correlated with NF-κB expression. Mechanistically, probiotics suppressed neuroinflammation by down-regulating pro-inflammatory cascades TNF-α, NLRP3, IL-1β, and NF-κB activation. Furthermore, treatment suppressed amyloidogenic processing via decreased APP mRNA and enhanced Aβ clearance through upregulation of LRP1 and modulation of AGER. These findings provide integrative evidence that probiotics exert neuroprotective and immunomodulatory effects, supporting their translational potential as a preventive strategy against AD-related cognitive decline.