Gut Bacteria Linked to Arthritis

Scientists have discovered a potential new cause of rheumatoid arthritis: your gut. The microbiota in your gut helps to crowd out infectious germs and digest food. Earlier studies have shown that microbiota are involved in obesity and allergies, and now new research shows the bugs may also be partially responsible for rheumatoid arthritis.

Gut bacteria play an important role in fighting off infections and aiding the immune system. Rheumatoid arthritis is an autoimmune disease involving an immune system attack on the thin membrane surrounding the joints called the synovium. This causes a build up of fluid in the joints, causing pain and inflammation.

A new study from New York University suggests that a specific microbe may contribute to systemic inflammation in the body. When combined with other factors like smoking, environment, and genetics, the microbe, called Prevotella copri, could set the stage for rheumatoid arthritis.

Researchers tested fecal samples from 114 New Yorkers, some of whom had been living with RA for years, others who had been recently diagnosed with RA, some had psoriatic arthritis, and others were healthy. In the group of recently-diagnosed RA patients, 75% of patients had Prevotella copri , compared to 37% of the other arthritic patients and 21% of the healthy participants.

The researchers then tested lab mice to see what would happen when levels of  Prevotella copri  were intentionally increased. The mice with Prevotella copri  didn’t develop arthritis but they did have significantly more inflammation in the gut.

“That they were able to associate one bacterium with one pathology is remarkable,” said Yasmine Belkaid, an immunologist at the National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, who commented on the study in the magazine Science Now.

If this research is confirmed in other studies, it could open the way future new treatments for RA, including supplements with probiotics to crows out the harmful microbes, or anti-biotics. These treatments would likely still need to be combined with other proven treatments for arthritis, including exercise and chiropractic care.


Scher, J. U. et al. Expansion of intestinal Prevotella copri correlates with enhanced susceptibility to arthritis. eLife doi:10.7554/eLife.01202.

Skwarecki, B. Gut bacteria may cause rheumatoid arthritis. Science Now.

Written by: Marissa Luck on December 20, 2013.on December 19, 2013.
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