An immune reaction to an intestinal bug can cause rheumatoid arthritis

An immune reaction to an intestinal bug can cause rheumatoid arthritis

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Is an immune reaction to gut bacteria to blame for rheumatoid arthritis? Image credit: Stefania Pelfini, La Waziya Photography/Getty Images.
  • The study found high levels of antibodies against proteins from gut bacteria in people at risk of rheumatoid arthritis and those who already have the disease.
  • Previous research has implied a high level of intestinal bacteria, the so-called Prevotella coverin rheumatoid arthritis.
  • P. cover helps digest dietary fiber in the gut and has been linked to several health benefits, but researchers have also linked it to gut inflammation.
  • The authors of the new study speculate that Prevotella species may escape from the gut and enter the bloodstream, where they trigger an immune response.

Rheumatoid arthritis is an autoimmune condition in which the immune system attacks the tissues of the joints, especially the knees, hands and wrists. This causes inflammation and painful swelling.

The Rheumatoid Arthritis Support Network estimates that the disease affects more than 1.3 million people in the United States and up to 1% of the world’s population.

According to Centers for Disease Control and Prevention (CDC), people with rheumatoid arthritis often first experience mild symptoms in their 60s, which gradually worsen over time.

However, antibodies that target one’s own tissues can circulate in the blood for several years before the onset of rheumatoid arthritis.

Scientists believe that genetic and environmental factors conspire to cause the disease. Known environmental factors include smoking, diet and gut dysbiosis – an unhealthy imbalance in the community of microorganisms in the gut.

One particular bacterium that appears repeatedly in studies of rheumatoid arthritis is Prevotella cover.

In 2013, a study found that three-quarters of people with newly diagnosed, untreated rheumatoid arthritis had P. cover in their intestines, compared to only a fifth of healthy controls.

Another studypublished in 2019, found larger quantities Prevotella species in the guts of people at risk of rheumatoid arthritis before they developed the disease, compared to controls.

P. cover there is mixed reputation. It is a friendly or commensal gut bacterium that helps digest dietary fiber and is associated with health benefits such as reduced visceral fat and improved glucose metabolism.

But researchers have also linked it to insulin resistancehigh blood pressureand chronic intestinal inflammation.

Now researchers at the University of Colorado Denver in Aurora, CO, have added evidence to that effect P. cover helps to cause rheumatoid arthritis and affects the development of the disease.

Scientists have found antibodies to a protein from P. cover in the bloodstream of both a person with rheumatoid arthritis and a person at risk of the disease.

“We hope that these findings can help in further elucidating the complex [causative role] bacterial commensals in people who are at risk of developing [rheumatoid arthritis] and in those with [rheumatoid arthritis] in order to be able to develop targeted therapies aimed at providing better treatment and ultimately disease prevention,” says the corresponding author. Jennifer A. Seifert.

Medical news today asked Seifert whether it is possible to prevent or treat rheumatoid arthritis by correcting gut dysbiosis, for example with probiotics or faecal transplants.

“It’s hard for us to make a definitive link between gut dysbiosis regulation and disease prevention this early in our research, but it’s something we’re invested in further research into potential viral and bacterial drivers of disease,” she said.

The researchers published their findings in Arthritis and rheumatology.

They speculate that some species of Prevotella, in particular P. coverthey can bind to the intestinal lining and escape into the bloodstream, where they trigger an immune response.

Bacteria can also attack joints and contribute to immune reactions there.

The new study compared 98 patients with established rheumatoid arthritis and 67 people at high risk of developing rheumatoid arthritis, with an equal number of matched, healthy controls.

They looked for antibodies that specifically target one of the bacteria’s proteins, called p27, which is known to trigger immune responses.

Compared to the control population, people with rheumatoid arthritis had higher levels of two types of antibodies, known as IgA and IgG, that target the protein.

People who were at risk of developing rheumatoid arthritis and those who had been diagnosed with the disease for less than a year had an overall higher level of IgG compared to the protein.

In contrast, patients with established rheumatoid arthritis had significantly increased levels of protein-targeted IgA.

The researchers conclude that the bacterium may help trigger the early onset of rheumatoid arthritis and later play a role in causing joint inflammation.

They point out that the gut microbiota plays a vital role in regulating inflammation and can cause autoimmune diseases when out of whack.

“We would like to investigate further in a larger cohort of associations [between RA and p27] stratified by disease stage and autoantibody status and comparing that to other bacteria and viruses we study.”

– Jennifer Seifert

She added that they have also started researching the immune effects P. cover and other species of interest through analyzes of gut microbiota samples.

Poor nutrition and stress they are known to worsen the symptoms of rheumatoid arthritis.

“I personally think that a diet high in vegetables, fruits, fiber and unsaturated fats — nuts, for example — is the most powerful diet for reducing inflammatory cascades,” he said. dr. Brett Smitha rheumatologist at Tennessee Direct Rheumatology and East Tennessee Children’s Hospital, both in Knoxville, who was not involved in the study.

He said MNT that diets containing twice weekly wild-caught fish have also shown benefits.

“Maintaining health body weightroutine exercise of moderate intensity and not smoking all have the potential to influence gut dysbiosis and reduce the risk of [rheumatoid arthritis]”, he added.

A small studypublished in 2020, found that people with rheumatoid arthritis who were most adherent Mediterranean diet had less inflammation and less severe disease.

The same people had a healthier gut microbiota, with an “almost complete absence”. P. cover.

Another study suggests that probiotics could slow the progression of rheumatoid arthritis without the side effects associated with immunosuppressant treatment.

In a mouse model of rheumatoid arthritis, Prevotella histicola reduced the frequency and severity of the disease.

“I’m sure there are many labs looking at different options for modulating gut bacteria for therapeutic purposes,” he said Ph.D. Veena Tanejaat the Mayo Clinic College of Medicine in Rochester, MN.

“We are exploring different aspects P. histicola“, she said MNT.

The authors of the new study admit that it had some limitations.

They note that they only measured reactivity to one unit P. cover protein, p27, which may limit their ability to assess the immune response to the bacterium.

This protein may be clinically important only for a subset of patients with rheumatoid arthritis.

Besides, they write it P. cover is only one of several organisms that can affect the immune system in this disease.

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