New research suggests bacterial disturbances in the gut may play a role in autoimmune attacks on the joints.

Researchers at New York University School of Medicine have linked a species of intestinal bacteria known as Prevotella copri to the onset of rheumatoid arthritis, the first demonstration in humans that the chronic inflammatory joint disease may be mediated in part by specific intestinal bacteria.

The new findings add to growing evidence that the trillions of microbes in our body play an important role in regulating our health, the researchers say.

“The human gut is home to hundreds of species of beneficial bacteria, including P. copri, which ferment undigested carbohydrates to fuel the body and keep harmful bacteria in check,” noted a university press release. “The immune system, primed to attack foreign microbes, possesses the extraordinary ability to distinguish benign or beneficial bacteria from pathogenic bacteria. This ability may be compromised, however, when the gut’s microbial ecosystem is thrown off balance, causing inflammation.”

At this stage, though, “We cannot conclude that there is a causal link between the abundance of P. copri and the onset of rheumatoid arthritis,” investigator Dan R. Littman, M.D., Ph.D., says. “We are developing new tools that will hopefully allow us to ask if this is indeed the case.”