External capsule protects gum disease-causing bacteria from immune response

November 17, 2011

(Medical Xpress) -- The capsule of Porphyromonas gingivalis, the bacterium that causes gum disease, provides stealth, boosting the bacterium’s virulence, according to a paper published in the November Infection and Immunity. Call it a sugar coating, if you will, for in fact, the capsule is made from sugar molecules, which do not ordinarily elicit immunity. Thus it hides the bacterium’s proteins within, preventing immune response.

In the study, the researchers, led by Janina P. Lewis of Virginia Commonwealth University, Richmond, compared the ability of normal, and mutant bacteria that were missing the capsule, to activate the immune system, to enter eukaryotic cells (the kind that are present in multicellular organisms), to cause disease, and to survive in mice. “The mutant bacteria activated the host to a greater extent, and thus, were more easily killed by eukaryotic cells,” says Lewis. “Thus, the capsule protects the bacteria and allows them to survive unnoticed in our bodies.”

Capsules also protect both bacteria and fungi, including P. gingivalis, as per this report, from being engulfed by the immune system’s phagocytes (phago=eat; cyto=cell) and from being identified by dendritic cells as dangerous, thus marking them for destruction by antibodies. Conversely, in the study, mutant, non-encapsulated P. gingivalis were rapidly engorged by immune , and killed.

“Thus, anything that would interfere with generation of capsule, such as drugs interfering with the action of enzymes involved in synthesis of the sugar coat, could be used in treatment of periodontal disease, and importantly, could have broader implications for prevention of more serious diseases,” by other encapsulated , such as pneumonia, anthrax, meningitis, endocarditis, and gastroenteritis, says Lewis.

Explore further: Closer to an effective treatment for gum disease in smokers

More information: A. Singh, T. Wyant, C. Anaya-Bergman, J. Aduse-Opoku, J. Brunner, M.L. Laine, M.A. Curtis, and J.P. Lewis, 2011. The capsule of Porphyromonas gingivalis leads to a reduction in the host inflammatory response, evasion of phagocytosis, and increase in virulence. Infect. Immun. 79:4533-4542.

Related Stories

Closer to an effective treatment for gum disease in smokers

May 11, 2009

Scientists in the USA have discovered why smokers may be more prone to chronic gum disease (periodontitis). One of the bacteria responsible for this infection responds to cigarette smoke - changing its properties and the ...

Unmasking anthrax for immune destruction

April 30, 2010

Anthrax-causing bacteria can be engineered to shed their invisibility cloaks, making it easier for the immune system to eradicate it, according to a new study published in Microbiology. The work could lead to new measures ...

Researcher uses card trick to reveal unconscious knowledge

November 17, 2011

(Medical Xpress) -- Spanish neuroscientist Luis Martínez of the Institute of Neurosciences in Alicante, has shown that an exception exists regarding “change blindness” and it can be demonstrated by using ...

Recommended for you

In cells, some oxidants are needed

August 18, 2016

Within our bodies, high levels of reactive forms of oxygen can damage proteins and contribute to diabetic complications and many other diseases. But some studies are showing that these reactive oxygen species (ROS) molecules ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.