Gum bacteria implicated in Alzheimer's and other diseases
Summary:
Researchers
are reporting new findings on how bacteria involved in gum disease can travel
throughout the body, exuding toxins connected with Alzheimer's disease,
rheumatoid arthritis and aspiration pneumonia. They detected evidence of the
bacteria in brain samples from people with Alzheimer's and used mice to show
that the bacterium can find its way from the mouth to the brain.
The bacterium, Porphyromonas
gingivalis, is the bad actor involved in periodontitis, the most serious
form of gum disease. These new findings underscore the importance of good
dental hygiene as scientists seek ways to better control this common bacterial
infection.
"Oral hygieneis very important throughout our life, not only for having a beautiful smile
but also to decrease the risk of many serious diseases," said Jan Potempa,
PhD, DSc, a professor at the University of Louisville School of Dentistry and
head of the department of microbiology at Jagiellonian University in Krakow,
Poland. "People with genetic risk factors that make them susceptible to
rheumatoid arthritis or Alzheimer's disease should be extremely concerned with
preventing gum disease."
While previous
researchers have noted the presence of P. gingivalis in brain samples
from Alzheimer's patients, Potempa's team, in collaboration with Cortexyme,
Inc., offers the strongest evidence to date that the bacterium may actually
contribute to the development of Alzheimer's disease. Potempa will present the
research at the American Association of Anatomists annual meeting during the
2019 Experimental Biology meeting, held April 6-9 in Orlando, Fla.
The researchers
compared brain samples from deceased people with and without Alzheimer's
disease who were roughly the same age when they died. They found P.
gingivalis was more common in samples from Alzheimer's patients, evidenced
by the bacterium's DNA fingerprint and the presence of its key toxins, known as
gingipains.
In studies using
mice, they showed P. gingivalis can move from the mouth to the brain
and that this migration can be blocked by chemicals that interact with
gingipains. An experimental drug that blocks gingipains, known as COR388, is
currently in phase 1 clinical trials for Alzheimer's disease. Cortexyme, Inc.
and Potempa's team are working on other compounds that block enzymes important
to P. gingivalis and other gum bacteria in hopes of interrupting their
role in advancing Alzheimer's and other diseases.
The researchers
also report evidence on the bacterium's role in the autoimmune disease
rheumatoid arthritis, as well as aspiration pneumonia, a lung infection caused
by inhaling food or saliva.
"P.
gingivalis's main toxins, the enzymes the bacterium need to exert its
devilish tasks, are good targets for potential new medical interventions to
counteract a variety of diseases," said Potempa. "The beauty of such
approaches in comparison to antibiotics is that such interventions are aimed
only at key pathogens, leaving alone good, commensal bacteria, which we
need."
P. gingivalis commonly begins to infiltrate the gums during the
teenage years. About one in five people under age 30 have low levels of the
bacterium in their gums. While it is not harmful in most people, if it grows to
large numbers the bacteria provoke the body's immune system to create
inflammation, leading to redness, swelling, bleeding and the erosion of gum
tissue.
Making matters
worse, P. gingivalis even causes benign bacteria in the mouth to
change their activities and further increase the immune response. Bacteria can
travel from the mouth into the bloodstream through the simple act of chewing or
brushing teeth.
The best way to
prevent P. gingivalis from growing out of control is by brushing and
flossing regularly and visiting a dental hygienist at least once a year,
Potempa said. Smokers and older people are at increased risk for infection.
Genetic factors are also thought to play a role, but they are not well
understood.
- Source:
- Experimental Biology
