Researchers discover periodontitis bacterium
ANN ARBOR, Mich., USA: Although oral health experts have known for decades that bacteria are responsible for periodontitis, it is largely unknown which bacterium causes the disease. However, researchers from the University of Michigan have isolated a bacterium recently. They hope that this discovery will help develop new therapies to treat infected patients.
Using a mouse model, researchers at the University of Michigan School of Dentistry and the University of Michigan Medical School isolated NI1060, a mouse-specific bacterium that is related to bacteria associated with the development of aggressive periodontitis in humans.
In the study, the researchers examined damaged gingiva between the molars of mice and observed that the bacterium accumulated at the damaged sites in particular. In order to prove that NI1060 caused the disease, they induced it into germ-free mice, which resulted in bone loss, a condition that could previously not be explained by the activity of gingiva-causing bacteria only.
In addition, the experiments revealed that Nod1, a protein receptor that lines the human oral cavity and stimulates immune reaction, is activated by NI1060. "Although Nod1 is part of the human protective mechanisms against bacterial infection, in the case of periodontitis, accumulation of NI1060 stimulates the receptor to trigger neutrophils and osteoclasts, which are cells that destroy bone in the oral cavity," said Dr. Naohiro Inohara, a research associate professor at the university's Department of Pathology.
The study, titled "Induction of Bone Loss by Pathobiont-Mediated Nod1 Signaling in the Oral Cavity," was published in the May issue of the Cell Host and Microbe journal.