In Alzheimer's disease (AD), the amyloid-β (Aβ) protein begins to accumulate in the brain 20 years prior to any dementia symptoms manifestation, in which Aβ aggregates in the brain, causing destruction of nerve cells and resulting in memory impairments. Lifestyle and diet appear to inhibit Aβ production and amyloid deposition. Therefore, identifying factors that prevent Aβ production and administering them before the onset of AD, may be an effective preventive method. Lactic acid bacteria (LAB) exhibit various health effects on the host and are expected to have protective effects on neurological functions via brain-gut correlation. However, the protective effects of LAB against Aβ are not well understood. We investigated whether LAB feeding could ameliorate the toxicity of Aβ peptide accumulation in transgenic Caenorhabditis elegans expressing the human Aβ peptide in neurons or muscle as an AD model. Aβ expressed in muscle caused myopathy and worm paralysis, while Aβ in neurons disturbed chemotactic activity. Among 14 screened strains, Lactococcus laudensis (LL) and Pediococcus parvulus (PP) prevented the AD worms from losing their chemotaxis behavior and becoming paralyzed by the Aβ peptide. Immunostaining and western blotting indicated that Aβ peptide was significantly suppressed in worms fed these two strains, and binding of the Aβ to vitellogenin was particularly inhibited. Conversely, the mRNA level of the Aβ gene did not change between LL- or PP-fed worms and the control. In conclusion, LL and PP alleviate neurotoxicity by inhibiting Aβ accumulation; AD model worms can be used to screen efficient LAB for AD prevention.
Keywords: Caenorhabditis elegans; Lactic acid bacteria; Neuropathy.
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