Researchers Find a Bacterial Cause of Rheumatoid Arthritis
Rheumatoid arthritis is one of the most
mysterious health conditions. Even though it’s widespread - affecting 1%
of the world population, including over 1.3 million Americans as per
the Rheumatoid Arthritis Support Network - we still don’t know what
triggers it. Researchers from the University of Colorado Denver say they
found the cause - the overgrowth of a bacterium called Prevotella copri
in the gut.
Understanding Rheumatoid Arthritis (RA)
RA is an autoimmune condition that begins
when the immune system mistakenly attacks its own healthy tissues. Apart
from the joints, rheumatoid arthritis can damage other body parts, such
as the heart, blood vessels, lungs, skin, and vision.
Symptoms of rheumatoid arthritis include:
- Joint stiffness, especially in the morning
- Tender and swollen joints that feel warm to the touch
- Firm bumps under the skin, commonly around the elbows.
The Centers for Disease Control and Prevention (CDC) suggest that mild
symptoms of the disease usually appear around age 60 and gradually
worsen over time, but RA can sometimes affect people in their 30s to 50s
too.
Patients suffering from RA may also
experience fatigue, loss of appetite, and fever years before the joint
symptoms appear. That’s because the antibodies that damage the body’s
own cells appear in the blood years before the onset of the first
recognizable arthritis symptoms.
This naturally makes us ask the question -
what known factors contribute to the development of rheumatoid
arthritis? For a while, we’ve known that genetics and lifestyle habits
like smoking and diet play a role, but a growing body of research also
suggests that intestinal dysbiosis, or an imbalance of gut
microorganisms, may also be responsible for the appearance of RA.
More recently, scientists have managed to isolate a particular bacterium
implicated in the development of rheumatoid arthritis - Prevotella
copri.
What is Prevotella copri (P. copri)?
P. copri is generally considered a friendly gut bacterium that aids in
the digestion of dietary fiber. The bacterium is even associated with
improved glucose metabolism and a reduction in visceral fat (fat that
develops between the internal organs). On the flip side, some scientists
have linked P.copri to hypertension, insulin resistance, and chronic
gut inflammation.
To that list of dangerous effects, a recent
study published in Arthritis and Rheumatology has also added P. copri’s
ability to trigger rheumatoid arthritis. The researchers found
antibodies to P. copri in the blood sample of people with rheumatoid
arthritis and those with an increased risk of the disease.
A study has found high levels of antibodies against a protein from a gut
bacterium in people at risk of rheumatoid arthritis and those who
already have the disease. A different study from 2019 that analyzed the
gut bacteria species in people with RA also more Prevotella bacteria in
samples taken from rheumatoid arthritis patients compared to controls.
Lastly, an even earlier study specified that 75% of people recently
diagnosed with rheumatoid arthritis had P. copri in the GI system
contrasted with only 20% of healthy controls.
This evidence suggests that either the presence or an overgrowth of P.
copri seems to contribute to the development of rheumatoid arthritis.
Gut Bacteria May Be Linked to Autoimmune Conditions
The authors believe that P. copri can
travel from the gut into the bloodstream, where it triggers an
inflammatory immune response. The bacterium may even be able to reach
the joints and cause inflammation there.
The 2022 study we reviewed in depth examined specific antibodies in the
blood that target P.copri. These two antibodies, called IgA and IgG, are
known to provoke chronic inflammation. 98 patients with rheumatoid
arthritis and 67 with an increased risk of rheumatoid arthritis, and an
equal number of healthy control subjects were involved in the study.
When compared to controls, the participants with rheumatoid had elevated
levels of both antibodies, whereas those with a higher risk of RA had
increased levels of just IgG.
These results suggest that P.corpi can cause inflammation in the joints
or even contribute to the early onset of rheumatoid arthritis. In
addition, these findings point to the fact that an overgrowth of gut
microbiota may play a more significant role than anticipated in the
development of autoimmune diseases in general.
That being said, the authors of the 2022 study recognize that P. copri
may be the trigger behind only a subset of RA patients, as other gut
bacteria and non-bacterial causes may also be able to increase
inflammation and cause the condition.
Can treating gut dysbiosis help rheumatoid arthritis?
An unhealthy diet and elevated stress
levels are known to exacerbate the symptoms of rheumatoid arthritis. So,
would the inverse be true as well? Could things like taking probiotics
or maintaining a healthy diet reduce symptoms of RA or even reduce the
risks of developing this condition?
There’s some emerging research that says ‘yes’! For example, a paper
from 2020 found that maintaining a Mediterranean diet can reduce
inflammation in patients with rheumatoid arthritis. According to the
study, the participants also had a healthier gut microbiome, almost
completely free of P. copri.
In addition, probiotics can slow down the progression of RA and lower
the risk of side effects in RA patients on immunosuppressant medication
according to research. Last but not least, rheumatologists say that a
combination of moderate exercise, not smoking, and a healthy diet can
address gut dysbiosis and reduce the risk of RA.