How periodontal disease contributes to the development
Rheumatoid arthritis: how periodontal disease contributes to its development
Rheumatoid arthritis often begins in the finger joints.
© Source: Adobe Stock/ hriana
Periodontal disease can contribute to rheumatoid arthritis (RA) and may even trigger the autoimmune disease in susceptible people. A US research team has now determined the mechanisms of this long-suspected connection in detail. “The work establishes an immunological connection at a very high and modern level,” says Ulf Wagner, Vice President of the German Society for Rheumatology (DGRh), who was not involved in the study. It is unclear whether better oral hygiene can improve existing joint inflammation.
In Germany, about one percent of adults have rheumatoid arthritis. Women are affected much more often than men. Usually the joint problems – often in fingers, toes, elbows or knees – develop after the age of 50. In the disease, the immune system attacks the joints for reasons that have not yet been clarified.
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Half of the population is affected by periodontal disease
It has long been suspected that such autoimmune reactions can be caused by infections. Periodontosis, an inflammation of the periodontium, affects almost half of the population and is noticeably common in people with rheumatoid arthritis, writes the team led by immunologist William Robinson from Stanford University in California in the journal Science Translational Medicine.
This means that bacteria from the oral cavity can enter the bloodstream as a result of this permanent inflammation. The fact that arthritis patients with acute gum problems often experience worsening of the symptoms also speaks for the involvement of periodontal disease in joint inflammation.
A central involvement of certain antibodies has already been suspected. These so-called ACPAs (Anti-Citrullinated Protein Antibodies) are directed against certain proteins that are altered by enzymes as a result of inflammation – in technical jargon: citrullinated. Such ACPAs often precede the onset of symptoms by years and are associated with a particularly severe course of RA.
Oral bacteria enter the bloodstream
In order to clarify a possible connection, Robinson’s team examined blood samples from five RA patients over a period of one to four years – on average, each participant gave 67 samples.
After a whole series of analyzes and laboratory tests, the following picture emerges: In people with periodontal disease, oral bacteria – in the women examined it was mainly streptococci – get into the bloodstream. These bacteria activate different groups of immune cells in the blood. As part of this immune reaction, antibodies can develop that are actually directed against citrullinated proteins in the oral bacteria. However, these ACPAs cross-react with citrullinated proteins in human tissues, causing inflammatory joint disease.
The presence of bacteria from the mouth can trigger immune responses that likely contribute to the development of rheumatoid arthritis over time in susceptible people, the group writes. Since periodontal disease affects 47 percent of the population, but rheumatoid arthritis only one percent, additional factors must be involved in the development of the disease.
Oral hygiene is becoming more important
These factors included certain genetic traits, explains German expert Wagner. The study provides new target structures for the development of drugs through the precise characterization of immune cells involved in the disease.
In addition, according to the Head of Rheumatology at Leipzig University Hospital, oral hygiene in patients with rheumatoid arthritis should now be a greater focus of research. “The study reinforces the need for good oral hygiene, even if it will not be easy to prove that there is a benefit in rheumatoid arthritis.” It is questionable whether oral hygiene can help those patients who have already developed the autoimmune disease.
