A new study from the Forsyth Institute shows a link between periodontal (gum) disease and the formation of amyloid plaque, a hallmark of Alzheimer’s disease.
A growing body of new research shows that oral bacteria play an important role in the systemic diseases, such as colon cancer and heart disease. Recently, a study carried out by the Forsyth Institute (one of the main dental and craniofacial research centers in the world) in collaboration with Boston University, and published in the Journal of Neuroinflammationdemonstrates that gum disease can lead to changes in brain cells called microglial cells, responsible for defending the brain against the amyloid plaque.
Oral diseases cause health problems
Periodontal diseases represent a set of pathologies infectious diseases that attack the gums and supporting tissues of the tooth. In general, the disease begins with gingivitis: an inflammation of the gums linked to the accumulation of bacterial plaque on the teeth. Gingivitis is a common disease that can be complicated by lesions of the gum. When the bone that supports the teeth is affected, this produces periodontitis. The migration of oral bacteria to other places in the body takes place mainly via the bloodstream.
What are amyloid plaques?
THE amyloid plaques are toxic aggregates that form around neurons. They are found in particular in the case of certain neurodegenerative diseases, such as Alzheimer’s disease. They prevent, among other things, the proper functioning of neurons and neurotransmitters. THE lesions they produce cause the death of neurons and consequently the cognitive decline.
What is the impact of oral microbiota on health?
Dr. Alpdogan Kantarci, senior researcher at the Forsyth Institute and lead author of the study, said this research has provided important insights into how oral bacteria get to the brain and the role of neuroinflammation. in Alzheimer’s disease. He specifies : “In this study, we asked ourselves the question: can oral bacteria cause changes in brain cells?”. To answer this question, the researchers studied the functioning of microglial cells. These cells are a type of white blood cell macrophages, similar to amoebas. They roam the brain in search of lesions and infectious agents. They contribute to theelimination dead or damaged brain cells, likewise they (literally) gobble up the germs invaders. Forsyth scientists found that when exposed to oral bacteria, these cells became overstimulated and ate too much. “They essentially became obese“, said Dr. Kantarci: “They could no longer digest the amyloid plaque formations.”
Periodontal disease can cause a breakdown in our immune system
The discovery made by this study is capital, it shows how periodontal diseases can cause a failure in our immune system. Dr. Kantarci explains that periodontal disease generates lesions between the gums and the teeth: “The area of this lesion is the size of your palm“. He warns that this represents a real risk : “This is an open sore, which allows bacteria from your mouth to enter your bloodstream and travel to other parts of your body.“These bacteria can cross the blood-brain barrier and stimulate microglial cells in your brain.
The study used bacteria in the mouth of mice to cause gum disease in the same species. In this way, the scientists were able to follow the progression of periodontal disease in the mice and confirm that these same bacteria had traveled to the brain. They then isolated the microglial cells mouse brain to expose them to oral bacteria. This exposure stimulated microglial cells, activated neuroinflammation, and ultimately changed the way microglial cells process amyloid plaques.
“To prevent neuroinflammation and neurodegeneration, it will be essential to control oral inflammation”
For Dr. Kantarci, the fact of recognize how oral bacteria cause neuroinflammation will promote the development of strategies and treatments more targeted to fight diseases neurodegenerative. He stated : “This study suggests that to prevent neuroinflammation and neurodegeneration, it will be essential to control 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 can’t really prevent systemic diseases, like Alzheimer’s disease, in a reproducible way..”
This is the first time in a study that scientists have caused periodontal disease with specific bacteria in mice. This was intended to study the effects of the oral microbiota on the brain of the same animal. Having bacteria and cells of the same species brings the experience closer to the process that occurs naturally in humans.