Rheumatoid arthritis, an intestinal bacterium could be the cause

Behind rheumatoid arthritis there might be a intestinal bacterium: this is what emerges from a new study conducted by a group of researchers from the University of Colorado, in the United States and published in the journal Science Translational Medicine. Investigating the possible causes of this autoimmune and inflammatory disease, the scientists they discovered some kind of bacteriumpreviously unknown, present in the intestine about 20% of people who were diagnosed with rheumatoid arthritis or who produced the antibodies typical of the disease and that could be involved in its onset. According to the authors of the study, this discovery could not only shed light on the still unknown causes of rheumatoid arthritis, but also lead to the development of new therapies.

The mysterious origins of rheumatoid arthritis

Rheumatoid arthritis is one disease autoimmune and inflammatory that hits about 1% of the world population, in which the immune system affects For error the healthy cells of the body. In particular, a specific type of antibodies, the proteins that usually mediate the immune response against pathogens such as viruses and bacteria, attack the body’s tissues, especially those of joints hands, wrists and knees (although, in rarer cases, rheumatoid arthritis can also affect other tissues, causing problems in the lungs, heart, eyes and other organs), generating inflammation and tissue damage which in turn leads to chronic pain, instability and deformations affecting the affected joints.

Although this disease has been under study for many years, its cause and the origins of antibodies responsible for the autoimmune response they are still unknown. Among the various hypotheses examined by scientists is the one that suggests that the mucosa of sites such as mouth, lungs and intestines have a central role in triggering the responses of the immune system occurring at the onset of rheumatoid arthritis, well before the onset of symptoms, and then perpetuating as the disease progresses. Specifically, the researchers have examined for antibodies in the blood of a sample of people to identify those at risk for rheumatoid arthritis.

“When we looked at those antibodies, we found that one type belongs to the class of antibodies that we normally see circulating in the disease, but the other is an antibody that we usually associate with our mucosa, be it oral, intestinal or pulmonary. So we started asking ourselves, ‘There may be something in the mucosa that is causing rheumatoid arthritis? ‘”said Kristine Kuhn, who coordinated the team of researchers.”Specifically, we wondered if bacteria in the microbiomethe community of microorganisms living in the gut, could be the ones that activate the immune response that leads to rheumatoid arthritis”, He writes on The Conversation Megan Chriswell, first author of the study.

Results and future prospects

At this point, to identify against which component of microbiome could be responsible for the autoimmune response, the researchers exposed the feces of people at risk for rheumatoid arthritis to the mucosal antibodies found earlier, isolating only the bacterial species that reacted with them. In particular, one previously unknown specieswhich Chriswell proposed calling Subdoligranulum didolesgii and whose diffusion among the general population is not known, was present in the intestines of about 20% of people diagnosed with rheumatoid arthritis or that they had the antibodies responsible for the disease in their circulation. According to the authors, these gut bacteria could activate the immune system of people with rheumatoid arthritiswhich, instead of targeting microorganisms, attacks the joints; the fact, then, that Subdoligranulum didolesgii being found only in the intestines of people with rheumatoid arthritis makes it one plausible cause of the onset of the disease in people at risk.

In fact, to further test their hypothesis, the scientists orally administered the newly discovered bacteria to laboratory mice: after just two weeks the animals began to produce antibodies typical of individuals at risk for rheumatoid arthritis and developing symptoms associated with the disease. If what this study suggests were corroborated by further research, there would not only be one greater clarity on the origins of rheumatoid arthritisbut they could be developed new prevention and treatment strategies.