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Updated: May 17, 2025
Author Spotlight: Accelerating Research on Bacterial Extracellular Vesicles Separation and Heterogeneity
Published on: September 1, 2023
The gut-brain axis in Alzheimer's disease is shaped by commensal gut microbiota derived extracellular vesicles
Junhua Xie1,2, Lien Van Hoecke1,2, Elien Van Wonterghem1,2
1VIB Center for Inflammation Research, VIB, Ghent, Belgium.
Abstract:
Emerging clinical and experimental evidence highlight the involvement of gut microbiota in the onset and progression of neurodegenerative diseases such as Alzheimer's disease (AD) via neuroinflammatory processes along the gut-brain axis. Despite this, the precise mechanisms governing gut microbial involvement in AD remain elusive. In this study, we observed that AppNL-G-F AD mice raised under germ-free (GF) conditions, display a reduced amyloid-β (Aβ) pathology, accompanied by a shift in microglial cells toward a less inflammatory state and increased phagocytotic efficiency. In addition, we demonstrate that gut microbiota depletion can protect against synaptic deficits in AD mice. Notably, administering bacterial extracellular vesicles (bEVs), i.e. nano-sized particles packed with bacterial components, derived from fecal slurry from specific pathogen-free housed AppNL-G-F AD mice, reversed the effects of GF conditions on both microglial activation and Aβ plaque accumulation. These findings reveal for the first time that commensal gut microbiota-derived bEVs have a major impact on AD pathology progression.
Insights
Gut bacteria influence Alzheimer's disease (AD) progression. Removing gut microbes reduced amyloid plaques and improved brain cell function in AD mice, suggesting a protective effect.
Area of Science:
- Neuroscience
- Microbiology
- Immunology
Background:
- Emerging evidence links gut microbiota to neuroinflammation in Alzheimer's disease (AD).
- The exact mechanisms of gut microbial influence on AD pathogenesis are not fully understood.
- The gut-brain axis plays a crucial role in mediating these interactions.
Purpose of the Study:
- To investigate the role of gut microbiota in Alzheimer's disease pathology.
- To elucidate the mechanisms by which gut microbes impact neuroinflammation and amyloid-β (Aβ) deposition.
- To determine the therapeutic potential of targeting gut microbiota-derived components.
Main Methods:
- Utilized germ-free (GF) Alzheimer's disease (AD) mouse models (App^/y mice).
- Assessed amyloid-β (Aβ) pathology, microglial cell state (inflammation, phagocytosis), and synaptic deficits.
- Administered bacterial extracellular vesicles (bEVs) derived from AD mouse fecal samples.
Main Results:
- Germ-free conditions significantly reduced Aβ pathology in AD mice.
- GF AD mice exhibited less inflammatory microglial cells with enhanced phagocytotic capacity.
- Depletion of gut microbiota protected against synaptic deficits.
- Administration of bEVs from AD mice reversed the protective effects of GF conditions, increasing microglial activation and Aβ plaque load.
Conclusions:
- Commensal gut microbiota critically influence AD pathology progression.
- Bacterial extracellular vesicles (bEVs) derived from gut microbes are key mediators of AD pathogenesis.
- Targeting bEVs represents a potential therapeutic strategy for Alzheimer's disease.
