Porphyromonas gingivalisand Alzheimer disease: Recent findings and potential therapies

Epidemiological studies have identified an association between periodontitis and Alzheimer disease (AD); however, the nature of this association has been unclear. Recent work suggests that brain colonization by the periodontal pathogenPorphyromonas gingivalismay link these two inflammatory and degenerative conditions. Evidence ofP. gingivalisinfiltration has been detected in autopsy specimens from the brains of people with AD and in cerebrospinal fluid of individuals diagnosed with AD. Gingipains, a class ofP. gingivalisproteases, are found in association with neurons, tau tangles, and beta-amyloid in specimens from the brains of individuals with AD. The brains of mice orally infected with P. gingivalis show evidence ofP. gingivalisinfiltration, along with various neuropathological hallmarks of AD. Oral administration of gingipain inhibitors to mice with established brain infections decreases the abundance ofP. gingivalisDNA in brain and mitigates the neurotoxic effects ofP. gingivalisinfection. Thus, gingipain inhibition could provide a potential approach to the treatment of both periodontitis and AD.