Lactobacilli Probiotics Prevent Amyloid-Beta Fibril Formation In Vitro

Alzheimer's disease (AD) is characterized by the buildup of extracellular aggregated amyloid-β (Aβ) peptides, following sequential enzymatic cleavage of amyloid precursor protein, along with intraneuronal accumulation of hyperphosphorylated Tau proteins and subsequent neuronal loss. Despite extensive research, the precise mechanisms underlying Aβ and Tau-mediated neurodegeneration remain elusive. Inhibiting protein aggregation has been a primary focus for mitigating neuronal toxicity. Probiotics have emerged as a promising preventative measure against cognitive decline in AD, with several in vivo and clinical trials demonstrating the efficacy of select bacterial strains in slowing AD progression. However, these studies lack direct molecular evidence on the effects of probiotics on Aβ aggregation kinetic. Inhibiting protein aggregation is key to reducing neuronal toxicity. While probiotics have shown promise in preventing cognitive decline in Alzheimer's disease, supported by in vivo and clinical studies, direct molecular evidence of their impact on Aβ aggregation kinetics remains lacking. In this study, we conducted bioinformatic and physicochemical assessments, including molecular docking of proteins derived from 13 probiotic strains against Aβ and Tau, identifying four strains predicted to efficiently inhibit Aβ aggregation. Kinetic studies confirmed that both the probiotic formulation and its derived supernatant significantly inhibited the conversion of monomeric Aβ and Tau into aggregated forms. To explore bioavailability, we administered the probiotic formulation to healthy individuals and detected its presence in stool samples, demonstrating survival through the gastrointestinal tract. These findings suggest that specific probiotic strains may serve as therapeutic candidates for targeting Aβ and/or Tau aggregation, with further studies warranted to assess their potential clinical utility in AD.