Gut bugs influence rheumatoid arthritis risk

London: Larger-than-normal populations of specific gut bacteria may trigger auto-immune diseases like rheumatoid arthritis, a team led by an Indian-origin scientist has found in a research that could help spot those at risk and even stop the crippling condition before it starts.

A team led by Dr Veena Taneja from the Mayo Clinic in the US found that billions of bacteria in the gut play a role in regulating the immune system. But an overabundance of a certain kind of gut bacteria – more than what is considered typical – could actually lead to autoimmune diseases like painful rheumatoid arthritis in people who may be susceptible to the disease, they found.

"A lot of people suspected that gut flora played a role in rheumatoid arthritis, but no one had been able to prove it because they couldn`t say which came first – the bacteria or the genes," said Dr Taneja.

"Using genomic sequencing technologies, we have been able to show the gut microbiome may be used as a biomarker for predisposition," she was quoted as saying by the Daily Mail.

The findings from a study in mice could help scientists predict which people are more likely to develop the painful condition and stop it in its tracks, the researchers said. They said that identifying new biomarkers in intestinal microbial populations and maintaining a balance in gut bugs could help stop rheumatoid arthritis, which affects nearly one per cent of the world`s population, before it starts.

In the study, published in the journal PLoS ONE, Dr Taneja and team genetically engineered mice with a human gene that is a strong indicator of predisposition to rheumatoid arthritis.

A set of control mice were engineered with a different variant of the gene, known to promote resistance to rheumatoid arthritis. The researchers used these mice to compare their immune responses to different bacteria and the effect on rheumatoid arthritis.

It was found that female mice had a tripled their risk of developing an autoimmune disease compared to male mice, which the researchers said is similar to how women are more likely to develop rheumatoid arthritis than men.

"This study is an important advance in our understanding of the immune system disturbances associated with rheumatoid arthritis," said co-author Dr Eric Matteson from Mayo Clinic.

"While we do not yet know what the causes of this disease are, this study provides important insights into the immune system and its relationship to bacteria of the gut, and how these factors may affect people with genetic susceptibilities to disease."

The researchers believe because the gut is presented with multiple insults daily through the introduction of new bugs, food sources and foreign antigens, it is continually teasing out what`s good and bad.

However, when good bacteria breach this barrier, they can trigger autoimmune responses. The body recognises them as out of place, and in some way this triggers the body to attack itself, they said.

The researchers believe these `humanised` mice could shed light on why women and other demographic groups are more vulnerable to autoimmune disorders and help guide development of new future therapies. "The next step for us is to show if bugs in the gut can be manipulated to change the course of disease," Dr Taneja added.