New York: Researchers, including one of Indian-origin, have discovered that unhealthy bacteria in your gut could be the culprit that causes rheumatoid arthritis, an autoimmune disorder that occurs when the body mistakenly attacks itself. As a result of this disease, the body breaks down tissues around joints, causing swelling that can erode bone and deform the joints. The disease can damage other parts of the body, including the skin, eyes, heart, lung and blood vessels. In a study published in the journal Genome Medicine, the researchers noted that an abundance of certain rare bacterial lineages causes a microbial imbalance that is found in rheumatoid arthritis patients. This study of rheumatoid arthritis patients, their relatives and a healthy control group aimed to find a biomarker -- or a substance that indicates a disease, condition or phenomena -- that predicts susceptibility 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," said Veena Taneja, immunologist at Mayo Clinic's Centre for Individualised Medicine in the US. The findings indicate that testing for specific microbiota in the gut can help physicians predict and prevent the onset of rheumatoid arthritis. "These are exciting discoveries that we may be able to use to personalise treatment for patients," Taneja said. Based on mouse studies, researchers found an association between the gut microbe Collinsella and the arthritis phenotype. The presence of these bacteria may lead to new ways to diagnose patients and to reduce the imbalance that causes rheumatoid arthritis before or in its early stages, study co-authors John Davis III, and Eric Matteson from Mayo Clinic said. In a separate study, published in the journal Arthritis and Rheumatology, the researchers explored another facet of gut bacteria. Taneja treated one group of arthritis-susceptible mice with a bacterium, Prevotella histicola, and compared that to a group that had no treatment. The study found that mice treated with the bacterium had decreased symptom frequency and severity, and fewer inflammatory conditions associated with rheumatoid arthritis. The treatment produced fewer side effects, such as weight gain and villous atrophy -- a condition that prevents the gut from absorbing nutrients -- that may be linked with other, more traditional treatments. While human trials have not yet taken place, the mice's immune systems and arthritis mimic humans, and shows promise for similar, positive effects.