Chronic periodontal disease (PD) – one of the most prevalent infectious inflammatory diseases affecting humans – has been positively linked to systemic inflammatory disorders, such as cardiovascular diseases (CVD), rheumatoid arthritis (RA) and chronic obstructive pulmonary disease (COPD). In a study published in the Sept. 12 issue of PLoS Pathogens, researchers have shown how a bacterium responsible for periodontal disease, Porphyromonas gingivalis, actively promotes the onset and severity of RA. The study shows that in addition to causing gingivitis, P. gingivalis worsens RA by leading to earlier onset, faster progression and greater severity of the disease, including increased bone and cartilage destruction.
Previous studies have indicated that people with periodontal disease have an increased incidence of RA, as compared to the general population, and periodontal disease is at least two times more prevalent in RA patients. Additional research has shown that P. gingivalis infection in the mouth occurs prior to the onset of RA, suggesting that the P. gingivalis bacterium is the likely culprit for the onset and continuation of the autoimmune inflammatory responses that occur in the disease.
In the current study, scientists from the University of Louisville School of Dentistry worked with an international team of scientists from the European Union Gums and Joints project to reveal how the bacterium produces a unique enzyme that converts arginine residues in protein into citrulline. The body, in turn, recognizes these citullinated proteins as intruders, leading to an immune attack that results in the chronic inflammation responsible for the destruction of bone and cartilage that is a hallmark of RA.
According to lead researcher, Jan Potempa, PhD, DSc, of the University of Louisville School of Dentistry Oral Health and Systemic Diseases, “Taken together, our results suggest that bacterial PAD may constitute the mechanistic link between P. gingivalis periodontal infection and rheumatoid arthritis, but this ground-breaking conclusion will need to be verified with further research.” Potempa said he is hopeful these findings will shed new light on the treatment and prevention of RA.