Rheumatoid arthritis affects 1 in 100 people worldwide. It causes inflamed, painful and swollen joints, often in the hands and wrists, and can lead to chronic pain and joint deformities and damage, as well as loss of joint function. It is unknown what causes this condition.
In our recently published study, my colleagues and I found an important clue to the potential culprit behind this disease: the bacteria in your gut.
What causes rheumatoid arthritis?
Rheumatoid arthritis is an autoimmune condition, meaning it develops when the body’s immune system starts attacking itself. Proteins called antibodies, which often help fight viruses and bacteria, start attacking the joints instead.
The origins of antibodies that cause rheumatoid arthritis have been the subject of research for many years. Some studies have shown that these antibodies can begin to form in areas such as the mouth, lungs, and intestines up to 10 years before symptoms appear. But until now, it was unclear why the researchers found these antibodies in these specific areas.
We wanted to investigate what might trigger the formation of these antibodies. Specifically, we wondered if the bacteria in the microbiome, a community of microorganisms that live in the gut, are the ones that activate the immune response that leads to rheumatoid arthritis. Since microbes often live in the same areas as the antibodies that trigger rheumatoid arthritis, we hypothesized that these bacteria might trigger the production of these antibodies. While these antibodies are intended to attack bacteria, we thought rheumatoid arthritis developed when it spread beyond the intestines to attack the joints.
First, we tried to identify the gut bacteria targeted by these antibodies. To do this, we exposed bacteria in the stool of a group of people at risk of developing rheumatoid arthritis to these antibodies, allowing us to isolate only the types of bacteria that respond to and bind to the antibodies.
We found that about 20% of people diagnosed with rheumatoid arthritis or who produce disease-causing antibodies have a previously unknown strain of bacteria in their gut. As a member of the Cherokee Nation in Oklahoma, I suggested that we name this species. Subdoligranum didolesgii (“didolesgii” means arthritis or rheumatism in Cherokee) as a nod to the contributions made by other Indigenous scientists to science, as well as the fact that rheumatoid arthritis affects Indigenous people at a higher rate than other populations.
Subdoligranum didolesgii It has not been detected in the stool of healthy people before, and it is currently unknown how common this bacterium is in the general population.
We also found that these bacteria can activate special immune cells called T cells in people with rheumatoid arthritis. T cells direct inflammatory responses in the body and are linked to the development of different autoimmune diseases.
These findings suggest that these gut bacteria may activate the immune systems of people with rheumatoid arthritis. But instead of attacking the bacteria, their immune systems attack the joints.
Why this bacteria?
It is still unknown why people with rheumatoid arthritis develop an immune response. Subdoligranum didolesgii. But we think it might be the culprit when it comes to rheumatoid arthritis because this bacterium is only found in the guts of people with rheumatoid arthritis, not in the guts of healthy people.
Although many immune responses occur in the gut, they are usually independent and do not spread to other parts of the body. However, we believe a particularly strong gut immune response is counterproductive. Subdoligranum didolesgii may allow antibodies to bypass the gut “firewall” and spread to the joints.
An oral dose to mice to confirm our hypothesis Subdoligranum didolesgii and watched their reaction. Within 14 days, the mice began to develop joint swelling and antibodies that attack their joints.
The future of rheumatoid arthritis treatment
My colleagues and I hope this research can shed light on the origins of rheumatoid arthritis. Our next goal is to discover how common these bacteria are in the general population and to 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 are unlikely to be adjunctive therapy for the microbiomes of patients with rheumatoid arthritis. Despite Subdoligranum didolesgii It may trigger an autoimmune response in some people with rheumatoid arthritis, with antibiotics eliminating both beneficial and harmful bacteria in the gut. In addition, eliminating bacteria does not necessarily stop the immune system from attacking the joints once it has started.
However, we think these bacteria could be used as tools to develop treatments for rheumatoid arthritis and as ways to prevent the disease from occurring in the first place.
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