New research is homing in on types of bacteria in the body that may be associated with some autoimmune diseases, including rheumatoid arthritis, or RA.

At the recent American College of Rheumatology Annual Scientific Meeting, researchers said that they think specific bacteria that live in the mouth and intestines activate cells that promote inflammation.

“The most important point is that we are now able to answer some of these questions and may be able to better understand potential triggering factors that lead to joint inflammation in RA and other diseases,” says Jose U. Scher, MD, director of New York University’s new Microbiome Center for Rheumatology and Autoimmunity and one of the lead investigators in the study. “We need to be cautious because this hypothesis generates expectations from doctors and patients, and the reality is that there is a lot of work ahead of us before we can come up with conclusions.” 

In the study, researchers from New York University’s Langone Medical Center used cutting-edge DNA sequencing technology to identify 100 percent of the bacteria in the mouth and intestines of eight people recently diagnosed with RA, three with psoriatic arthritis and nine who were healthy and didn’t have an autoimmune disease. “What we are doing is testing an old hypothesis with 21st-century technologies,” Dr. Scher explains.

Researchers say the new technology is allowing them to see some differences in those with autoimmune diseases and those without. The RA patients, for example, had more of a bacterial family called prevotellaceae in their intestinal fecal samples, and more of a type of oral bacteria called porphyromonas genus, than healthy patients had.

“We can say we have preliminary results looking at a particular set of bacteria that may seem present at a higher abundance in patients with RA,” Dr. Scher says. “Now we have the technological tools to look at this question, but we can not say we have an answer yet.”

David S. Pisetsky, MD, PhD, a professor of medicine at Duke University Medical Center in Durham, N.C., says the fact that researchers can find and identify hundreds if not thousands of bacteria types provides a level of detail never before seen. He believes that will go a long way in highlighting differences in people with RA from those without it.

“It’s part of an entirely new direction in analyzing the relationship between infection and disease,” Dr. Pisetsky says. “We are filled with bacteria. It’s probably stimulating or modifying our immune system and the question is, are there particular bacteria that would make you more or less likely to get a disease?”

Because studies looking into the relationship of bacteria and autoimmune disease are small and in early stages, it’s hard to tell what, if anything, the information means to patients now, Dr. Pisetsky adds. “I am going to follow [this emerging area of research] with interest to see how it develops.”