Fusobacterium nucleatum (F. nucleatum) is a common type of bacteria that proliferates in periodontal disease. It affects the gums and jawbone and, if untreated, results in unstable teeth and tooth loss.
The bacteria have been linked to conditions ranging from colorectal cancer to premature delivery of babies. Now Tufts scientists and colleagues have found another concerning link, this time from F. nucleatum to Alzheimer’s disease.
This finding has led Jake Jinkun Chen, professor of periodontology and director of the Division of Oral Biology at Tufts University School of Dental Medicine, to believe that targeting F. nucleatum could slow the spread and progression of at least two epidemics—periodontal disease, which affects 47% of U.S. adults over age 30, and Alzheimer’s, which afflicts 6.5 million Americans currently and is expected to increase to over 14 million by 2060.
“Our lab is the first to find that Fusobacterium nucleatum can generate systemic inflammation and even infiltrate nervous system tissues and exacerbate the signs and symptoms of Alzheimer’s disease,” Chen explained. Chen is a trained pathologist and professor at the School of Medicine and Graduate School of Biomedical Sciences.
The research, done in mice, shows that F. nucleatum results in an abnormal proliferation of microglial cells, immune cells in the brain that normally remove damaged neurons and infections and help maintain the overall health of the central nervous system. This oversupply of microglial cells also creates an increased inflammatory response, the researchers found. Chronic inflammation or infection is believed to be a key determinant in the cognitive decline that occurs as Alzheimer’s disease progresses.
In addition to showing how F. nucleatum and Alzheimer’s might be linked, the research suggests potential drug targets that could specifically quench the local as well as systemic inflammation caused by F. nucleatum in a periodontal environment. This is crucial, because Chen and colleagues are targeting their translational research at blocking the pathways between periodontal disease and not only Alzheimer’s, but also other diseases linked to inflammation as well, including Type 2 diabetes.