Monthly Archives: October 2013

P. Gingivalis – The Community Activist of Periodontal Disease with a Connection to Rheumatoid Arthritis

Recently I wrote about a study that established a connection between Alzheimer’s Disease and periodontal disease. The key finding in the study was the discovery of Porphyromonas gingivalis in the brains of Alzheimer’s patients.

I wanted to give this bacterium a little more attention and reveal its association to a harmful disease: rheumatoid arthritis.

Porphyromonas gingivalis

P. gingivalis is one of many bacteria in the mouth, but when it comes to gum disease it is the prime suspect.  It is known as one of the keystone bacterium which leads to periodontal disease. It has several qualities and tools which aid in destroying the supporting structures of teeth.

One of those tools is an enzyme called collagenase that injures the fibers that attach the teeth to the bone.

P. gingivalis is also very stubborn to antibiotics, due to several features of the bacterium. Specialized enzymes called gingipains help create a food supply engine for the bacteria, and cleverly impair the immune system’s attempts to eradicate it.

In its attempt to invade the structures of the mouth it also clears the way for other bacteria. It does this partly by changing the chemical stability of the oral cavity, which makes the environment more hospitable to infection by other damaging microbes. In this way, P. gingivalis works together with other bacteria known to cause periodontal disease and damage to the supporting structures of teeth.

Connection to Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease where the immune system attacks the body by creating systemic inflammation. It is commonly known to affect flexible joints, but also affects tissues and organs. It can also produce inflammation in the lungs, the membrane around the heart, and the whites of the eyes.

P. gingivalis is linked to Rheumatoid arthritis through an enzyme contained in the bacterium: PAD. One of the things PAD does is convert an amino acid called arginine into another amino acid called citrulline.

RA patients tend to have significant levels of antibodies to citrulline, which reflects a presence of this amino acid, and an immune response to it. Patients with RA tend to also have periodontal disease.

Interestingly, citrulline is also found among the destroyed cells found in Alzheimer’s disease, and in smokers.

Bacteria Must Be Removed by Periodontal Intervention

Gum disease, simplified, is a disease of bacterial infection and inflammation, both which attack and damage the supporting structures of the teeth.

It is becoming more established, year after year, that the damaging effects of periodontal disease are not limited to tooth loss. Exact cause and effect mechanisms are unclear, but the associations between gum disease and systemic diseases such as diabetes, heart disease, Alzheimer’s disease, and rheumatoid arthritis are clear.

Treatment of periodontal disease is not only critical  for keeping and maintaining healthy teeth, it is also an important contributor towards overall systemic health. Regular periodontal cleanings to remove harmful bacteria such as P. gingivalis are also crucial to both oral and systemic health.