Gum Disease Linked To Neuroinflammation

The study describes how gum disease can lead to changes in microglial cells which are responsible for protecting the brain from amyloid plaque proteins that are associated with cell death and cognitive decline, providing insight into how oral bacteria travels to the brain and the role of neuroinflammation in Alzheimer’s Disease (AD).

“We knew from one of our previous studies that inflammation associated with gum disease activates an inflammatory response in the brain,” said Dr. Alpdogan Kantarci, a senior member of staff at Forsyth and a senior author of the study. “In this study, we were asking the question, can oral bacteria cause a change in the brain cells?”

In plain terms, the researchers found that when the microglial cells were exposed to oral bacteria they became overstimulated and ate too much, basically becoming obese and could no longer digest plaque formations. This finding is significant for demonstrating the impact of gum disease on systemic health.

As for oral bacteria traveling to the brain, gum disease causes lesions to develop between the gums and teeth, think of this area as a whole and it would be around the size of your palm. Dr. Kantarci explains that this area is like an open wound that would allow the oral bacteria to enter your bloodstream to circulate to other parts of your body, and the bacteria can pass through the blood-brain barrier to stimulate the microglial cells in the brain. 

“Recognizing how oral bacteria causes neuroinflammation will help us to develop much more targeted strategies,” said Dr. Kantarci. “This study suggests that in order to prevent neuroinflammation and neurodegeneration, it will be critical to control the oral inflammation associated with periodontal disease. The mouth is part of the body and if you don’t take care of oral inflammation and infection, you cannot really prevent systemic diseases, like Alzheimer’s, in a reproducible way.”

The researchers reported that by using mouse oral bacteria to cause gum disease in lab mice, for the first time, they were able to track periodontal disease progression to confirm that bacteria has traveled to the brain. The researchers then isolated microglial cells from the brain and exposed them to oral bacteria to observe the cells becoming stimulated which activated neuroinflammation and changed how the microglial dealt with amyloid plaques.