Newly discovered types of bacteria in the microbiome may be to blame for rheumatoid arthritis

1 in 100 people in the world. It causes inflamed, painful and swollen joints, often in the hands and wrists, and can lead to loss of joint function, as well as chronic pain and joint deformity and damage. It is not known what causes this condition.

In ours recently published studymy colleagues and I have found an important clue to the potential culprit of this disease: the bacteria in your gut.

What causes rheumatoid arthritis?

Rheumatoid arthritis is autoimmune condition, which means it develops when the body’s immune system starts attacking itself. Proteins called antibodies, which normally help fight viruses and bacteria, start attacking the joints instead.

The origin of the antibodies that cause rheumatoid arthritis has been an area of ​​study for many years. Some research has shown that these antibodies can begin to form in places such as the mouth, lungs and intestines more than 10 years before symptoms appear. But until now, it was unclear why researchers were finding these antibodies in those specific areas.

We wanted to investigate what could trigger the formation of these antibodies. More precisely, we asked ourselves whether the bacteria in microbiome, a community of microorganisms that live in the gut, could be the ones that activate the immune response that leads to rheumatoid arthritis. Since microbes usually live in the same places as the antibodies that cause rheumatoid arthritis, we hypothesized that these bacteria could stimulate the production of these antibodies. We reasoned that although these antibodies were supposed to attack the bacteria, rheumatoid arthritis develops when they spread outside the gut and attack the joints.

We first sought to identify the intestinal bacteria targeted by these antibodies. To do this, we exposed bacteria in the feces of a subset of people who were at risk of developing rheumatoid arthritis to these antibodies, which allowed us to isolate only the bacterial species that reacted and bound to the antibodies.

The story continues

We discovered that a previously unknown type of bacteria is present in the guts of about 20% of people diagnosed with rheumatoid arthritis or produce disease-causing antibodies. As a member of the Cherokee Nation of Oklahoma, I suggested that we name this species Subdoligranulum didolesgii (“didolesgii” means arthritis or rheumatism in Cherokee) as a nod to the contributions other Native scientists made to science, as well as the fact that rheumatoid arthritis affects the native population at a higher rate than other populations.

Subdoligranulum didolesgii so far it has not been detected in the feces of healthy people, and it is currently unknown how widespread this bacterium is in the general population.

We also found that these bacteria can activate specialized immune cells called T cells in people with rheumatoid arthritis. T cells initiate inflammatory reactions in the body and are associated with development various autoimmune diseases.

These findings suggest that these gut bacteria may be activating the immune system of people with rheumatoid arthritis. But instead of attacking the bacteria, their immune system attacks the joints.

Why this bacteria?

It is still unknown why people with rheumatoid arthritis develop an immune response to Subdoligranulum didolesgii. But we think it could be the culprit when it comes to rheumatoid arthritis because this bacteria is only found in the guts of people with rheumatoid arthritis, not in the guts of healthy people.

While many immune responses occur in the intestines, are usually independent and do not spread to other areas of the body. However, we believe that a particularly strong intestinal immune response is against it Subdoligranulum didolesgii could allow the antibodies to bypass the intestinal “firewall” and spread to the joints.

To confirm our hypothesis, we administered an oral dose to mice Subdoligranulum didolesgii and watched their reaction. Within 14 days, the mice began to develop joint swelling and antibodies that attacked their joints.

The future of rheumatoid arthritis treatment

My colleagues and I hope that this research can shed light on the origins of rheumatoid arthritis. Our next goal is to find out how common these bacteria are in the general population and test whether the presence of these bacteria in the gut can lead to the development of rheumatoid arthritis in humans.

It is important to note that antibiotics unlikely to be helpful in treating the microbiome of patients with rheumatoid arthritis. Although Subdoligranulum didolesgii possibly triggering an autoimmune response in some people with rheumatoid arthritis, antibiotics remove both beneficial and harmful bacteria in the gut. Additionally, removing the bacteria will not necessarily stop the immune system from attacking the joints once it has already started.

Nevertheless, we believe that these bacteria can be used as tools to develop treatments for rheumatoid arthritis and, hopefully, ways to prevent the disease from occurring.

This article was republished from Conversation, an independent, non-profit news site dedicated to sharing the ideas of academic experts. He wrote it: Meagan Chriswell, University of Colorado Anschutz Medical Campus. If you found it interesting, you could subscribe to our weekly newsletter.

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Meagan Chriswell does not work for, consult with, own stock in, or receive funding from any company or organization that would benefit from this article and has disclosed no relevant affiliations other than her academic appointment.