The bacteria in your gut could play a role in rheumatoid arthritis, a new study suggests.
Researchers from the New York University Langone Medical Center found that people with newly diagnosed rheumatoid arthritis have a greater abundance of the intestinal bacteria Prevotella copri than people without the inflammatory disease, or those who have had the disease for a while but were managing it with treatment.
"Our own results in mouse studies encouraged us to take a closer look at patients with rheumatoid arthritis, and we found this remarkable and surprising association," study researcher Dan R. Littman, M.D., Ph.D., a microbiology and pathology professor at NYU, said in a statement. However, he cautioned that the study does not prove a causal link between the bacteria and rheumatoid arthritis.
Rheumatoid arthritis is an inflammatory condition that affects the lining of the joints -- usually in the hands and feet -- causing swelling, deformity of the joints and even erosion of the bone, the Mayo Clinic reported. Anywhere from 0.5 to 1 percent of the general population is estimated to have the condition, according to the Centers for Disease Control and Prevention.
The exact cause of the disease is unknown, but genetics seem to play a part in susceptibility to other factors (such as infections) that could lead to rheumatoid arthritis, the Mayo Clinic noted.
For the new study, published in the journal eLife, researchers obtained 44 fecal DNA samples from people newly diagnosed with rheumatoid arthritis who had not yet received immune-suppressive treatments, in addition to 26 fecal DNA samples from people with treated rheumatoid arthritis. They also collected 16 fecal DNA samples from people with psoriatic arthritis and 28 fecal DNA sample from healthy people. They conducted gene sequencing on the 16S gene of these samples.
P. copri bacteria was found in the most fecal samples from the newly diagnosed patients, with 75 percent of the samples carrying the bacteria. Meanwhile, 21.4 percent of the samples from the healthy people carried the bacteria, 11.5 percent of samples from the people with treated rheumatoid arthritis carried it, and 37.5 percent of samples from people with psoriatic arthritis carried it.
As to why people with chronic, treated rheumatoid arthritis experienced lower levels of this bacteria in their stool samples, "it could be that certain treatments help stabilize the balance of bacteria in the gut," study researcher Jose U. Scher, M.D., director of the Microbiome Center for Rheumatology and Autoimmunity at NYU Langone Medical Center's Hospital for Joint Diseases, said in the statement. "Or it could be that certain gut bacteria favor inflammation."