Microglia, the brain’s resident immune cells, play a vital role in managing brain inflammation and neurodegenerative diseases by eliminating amyloid-beta, a harmful protein linked to Alzheimer’s disease, and forming barriers around insoluble amyloid-beta deposits. A new study in mice shows that oral bacteria over-stimulate microglia, impairing their anti-amyloid properties.

Researchers induced periodontal disease in mice by placing ligatures around their teeth, creating an environment conducive to bacterial growth. Then they examined the effects of the disease on the animals' gums, bones, and microglial cells. They found that the gum infections caused progressive periodontal disease and bone loss in the mice. In addition, the severity of periodontal disease correlated with increased microglial cell activation in the brain. Then, the researchers exposed microglial cells to bacteria from the animals' infected gums. They found that this exposure increased inflammation and changes in the cells' ability to interact with amyloid-beta.

These findings suggest that periodontal disease influences the brain’s immune response via changes in microglial activation and their interactions with amyloid-beta. This link between gum and brain health underscores the potential importance of oral hygiene in preventing or managing neuroinflammatory conditions like Alzheimer’s disease.

Related studies have found that oral bacteria colonize the brain and release toxins that disrupt the blood-brain barrier, impairing its function and increasing the risk of Alzheimer’s disease. Learn more about the role of blood-brain barrier dysfunction in Alzheimer’s disease in this episode featuring Dr. Axel Montagne.

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