The role of gut bacteria has long been recognized as a major contributing factor in immune system functioning. Since rheumatoid arthritis is a disorder caused by a faulty immune system, researchers assumed that gut microbiota may play some role in the onset of rheumatoid arthritis. Veena Taneja, Ph.D., an immunologist at Mayo Clinic’s Center for Individualized Medicine together with her colleagues set out to see if this was truly the case.
The researchers conducted two separate studies to find out if there was a difference in the gut microbiota balance in arthritis patients and healthy subjects and also to see if treating rheumatoid arthritis with gut bacteria would give positive results. According to the study’s findings, an imbalance between good and bad gut bacteria can trigger the onset of rheumatoid arthritis in predisposed individuals. The research findings were published in Arthritis & Rheumatology and in Genome Medicine.
With more than 1.5 million Americans suffering from rheumatoid arthritis, the need for adequate treatment has become a major public health concern. Rheumatoid arthritis (RA) is an autoimmune disorder that mainly affects the synovial joints. The disease is caused by the immune system mistakenly attacking joint tissue causing it to break down which leads to swelling, pain, and erosion of bone and deformation of the joints.
Currently not much is known about the causes of RA and disease management is limited to NSAIDs, steroids, physical therapy, and surgery. Knowing more about the causes and mechanisms of this disorder would help many sufferers find relief from pain and improve overall mobility. The immune response in RA sufferers is influenced by both genetic and environmental factors. In other words, RA is a hereditary disorder that can be triggered or worsened by factors like smoking and inflammation.
Gut microbiota was also found to influence the development of diseases such as obesity as stated in an article published in Nature. Researchers at Mayo Clinic’s Center for Individualized Medicine conducted two separate researches, one on mice and the other on both human and mice subjects to test if gut microbiota influenced rheumatoid arthritis in any way.
The Human and Mouse Study
The researchers enrolled 40 RA patients from Rheumatology Clinic at Mayo Clinic. The study also included 32 controls who had no known autoimmune disorders and who were either the RA group’s first degree relatives or other controls with no known history of autoimmune disorders.
Researchers used fecal samples from the two groups to analyze their gut microbiota and found that RA patients had a greater number of rare bacterial lineages that are usually not abundant in the human intestinal tract. The researchers also observed less bacterial diversity in the RA group in comparison with controls.
Based on research on mice, the scientists found a link between the gut microbe Collinsella and a certain arthritis phenotype. John Davis III, M.D., and Eric Matteson, M.D., the study’s co-authors believe this may set new ways in early RA interventions when the presence of this strain of bacteria is detected. With more research, even preventive measures may be developed thanks to this study’s promising findings.
The Mouse Study
Researchers used humanized mice models to see if gut bacteria influenced the onset and severity in the arthritis-susceptible mice. The mice were treated with a type of bacteria naturally found in the human intestinal tract called Prevotella histicola. The mice treated with this strain of bacteria showed decreased incidence of disease development as well as less severe symptoms in comparison with controls. The mice also had fewer other inflammatory conditions that are frequently found in RA. Since the mice from this study had an immune system genetically similar to humans, the results seem promising for the development of future treatments for RA.
However, more studies preferably on humans are needed to determine if treating RA with bacteria is a viable option says the study’s co-author Joseph Murray, M.D., a gastroenterologist at Mayo Clinic. He also explains that since the bacteria from this study are a normal part of the human gut, this type of treatment would cause fewer side effects than conventional treatments for RA.
Rheumatoid arthritis is a painful and debilitating condition affecting a great number of people worldwide. Treatment options are currently limited to managing the symptoms of RA mainly because the causes of this autoimmune disorder remain unknown.
The new studies from the Mayo Clinic team of researchers give new insight into the possible factors that influence the onset and severity of rheumatoid arthritis. Since the balance of gut microbiota was found to have some effect on immune system functioning, treating autoimmune disorders by balancing gut microbiota might be a natural and safe approach to treating RA. However, more studies are needed to know for sure if this is truly the case.