Two new studies revealed that gut bacteria can cause rheumatoid arthritis, but can also be used to predict and prevent joint inflammation.

The first study, published in the journal Genome Medicine, suggests that the abundance of certain rare bacterial lineages in the gut, which is normally low abundance in healthy individuals, causes a microbial imbalance in patients suffering from rheumatoid arthritis.

On the other hand, the second study published in the journal Arthritis and Rheumatology suggests that a certain bacterium decreased symptom frequency and severity, and fewer inflammatory conditions associated with rheumatoid arthritis.

For the first study, the researchers analyzed the intestinal microbiota and metabolic signatures of mice to build a predictive profile for who is likely to develop rheumatoid arthritis and the course the disease will take. The researchers noted that the presence of the gut microbe Collinsella is associated to the arthritis phenotype. This bacterium can cause microbial imbalance, which in turn lead to rheumatoid arthritis.

"Using genomic sequencing technology, we were able to pin down some gut microbes that were normally rare and of low abundance in healthy individuals, but expanded in patients with rheumatoid arthritis," explained Veena Taneja, Ph.D., an immunologist at Mayo Clinic's Center for Individualized Medicine and lead author of the two studies, in a statement.

For the second study, the researchers treated a group of arthritis-susceptible mice with the bacterium Prevotella histicola and compared them to a group that did not receive the treatment. The researchers found out that the group of mice treated with the bacterium experience a decrease in symptom frequency and severity.

Furthermore, the treatment also caused ewer inflammatory conditions associated with rheumatoid arthritis, while producing fewer side effects, including weight gain and villous atrophy.

Rheumatoid arthritis is an autoimmune disorder that affects over 1.5 million people in the United States. It occurs when the body mistakenly attacks itself, breaking down tissues around joints, which causes swelling that is capable of eroding bones and deforming joints.