Gum disease might be cause of some arthritis flare-ups: Study

WASHINGTON: Patients with gum disease are less likely to respond to rheumatoid arthritis treatments, according to a well-documented medical mystery. However, new research may help explain the connection between gum disease and an otherwise disparate condition.

The findings, published in Science Translational Medicine, suggests that breaches in damaged gums allow bacteria in the mouth to seep into the bloodstream, activating an immune response that ultimately pivots to target the body's own proteins and causes arthritis flare-ups.

"If oral bacteria are getting in and repeatedly triggering immune responses relevant to rheumatoid arthritis, that could make it harder to treat," says Dana Orange, a professor of clinical investigation in the laboratory of Robert B Darnell at The Rockefeller University.

"When doctors encounter arthritis patients who do not respond to treatment, it would be worth it to make sure they aren't missing an underlying gum disease, which is quite treatable."

The Darnell lab had been following a small group of arthritis patients over the course of several years, collecting weekly blood samples and looking for changes in gene expression to help explain why painful flare-ups occur, when they noticed a surprising trend.

Two of their patients, who had moderate to severe periodontal disease, had repeated episodes of oral bacteria in their bloodstreams, even when they weren't having dental work. Orange knew that rheumatoid arthritis patients generally have autoantibodies in their bloodstream (rheumatoid arthritis is an auto-immune disease, wherein antibodies attack the body's own proteins and peptides).

In many cases, autoantibodies take specific aim at proteins bearing the signs of citrullination, a process by which one amino acid in the protein is converted into a different one.