Oral bacteria, associated with diseases of the mouth, have been increasingly implicated in systemic conditions like colon cancer and heart disease.
In a recent study by researchers from the Forsyth Institute, evidence now suggests a link between periodontal (gum) disease and Alzheimer’s disease, specifically, the formation of amyloid plaque, a characteristic feature of the neurodegenerative disease.
The paper, “Microglial cell response to experimental periodontal disease,” published in the Journal of Neuroinflammation, provides crucial insights into how oral bacteria travel to the brain and how neuroinflammation is involved in Alzheimer’s disease.
Role of Microglial Cells and Oral Bacteria
The researchers focused on brain cells called microglial cells, which are tasked with protecting the brain from amyloid plaque, a protein associated with cell death and cognitive decline in Alzheimer’s patients.
Dr. Alpdogan Kantarci, a senior member of the Forsyth staff and one of the study’s senior authors, noted from previous research that inflammation from gum disease prompts an inflammatory response in the brain.
The team wondered if oral bacteria could induce changes in brain cells.
Microglial cells, a type of white blood cell, help digest amyloid plaque.
The study found that when exposed to oral bacteria, these cells overeat, akin to becoming “obese,” according to Kantarci, impairing their ability to digest plaque formations.
Periodontal Disease and its Systemic Impact
Periodontal disease causes lesions to form between the gums and teeth.
These open wounds can enable mouth bacteria to enter the bloodstream, circulate throughout the body, and penetrate the blood-brain barrier, affecting brain microglial cells.
The research team induced gum disease in lab mice using mouse oral bacteria. By tracking the disease progression, they were able to confirm that the bacteria had reached the brain.
When brain microglial cells were exposed to oral bacteria, it stimulated the cells, triggered neuroinflammation, and altered the cells’ ability to handle amyloid plaques.
Implications for Alzheimer’s Disease Treatment
Understanding the role of oral bacteria in causing neuroinflammation is crucial for developing targeted treatment strategies, says Kantarci.
Controlling oral inflammation associated with periodontal disease may be vital for preventing neuroinflammation and neurodegeneration.
The study underscores the importance of oral health in systemic disease prevention, including conditions like Alzheimer’s disease.
The research is pioneering in inducing periodontal disease using mouse-specific bacteria to study the effects of the same-species oral microbiome on the brain, closely replicating the process in humans.
The study was published in the Journal of Neuroinflammation.
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