A growing amount of research is honing in on a surprising suspect in the cause of rheumatoid arthritis: our gut bacteria.
Doctors aren't entirely sure what triggers the disease, in which the body attacks its own joints, but several recent studies have found compelling links between gut microbes, rheumatoid arthritis, and other immune system disorders, The Atlantic reports.
In 2013, New York University rheumatologist Jose Scher published research that found that rheumatoid arthritis sufferers were much more likely to have a bug called Prevotella copri in their intestines than non-sufferers.
Then, in another study published in October, Scher found that patients with psoriatic arthritis, another kind of autoimmune joint disease, had significantly lower levels of other types of gut bacteria.
Scher is one of the nation's leading researchers attempting to determine how the microbiome — the various microbes that live in the gastrointestinal tract — affects our overall health, and how to use the gut as a way to target disease.
"This is frontier stuff," said Scher. "This is a shift in paradigm. By including the microbiome, we've added a new player to the game."
Scientists are particularly fascinated by how these bacteria influence the immune system. The incidence of many autoimmune diseases has been increasing in recent decades. Many microbiome researchers argue that at least some of this rise is due to changes in our bacterial ecosystem — through altered diet, a rise in antibiotic use, and decreasing contact with the natural world.
"We're losing microbes with each generation; they are going extinct. These changes have consequences," said NYU microbiologist Martin Blaser. "These organisms are part of our developmental choreography. They're part of who we are."
While many scientists are confident that immune cells in the gut are able to activate inflammatory cells throughout the body, including in joints, they still haven't determined the exact role bacteria play in triggering rheumatoid arthritis.
But Scher believes that one can alter the microbiome through diet. He notes that some patients with rheumatoid arthritis have benefitted from cutting out meat, or adopting a Mediterranean diet, though he's still not exactly sure how this helps.
Other people are focusing on bugs over diet. They believe products that contain "healthy bacteria" — such as yogurt, aged cheeses, and other foods that have probiotics or prebiotics — can help counteract health problems by boosting healthy gut bacteria, therefore realigning the immune system.
Right now, though, doctors aren't generally using microbes in patients to treat arthritis or other conditions, but Scher expects that to change.
"In 10 or 15 years I think the microbiome will be a key therapeutic option for some of these diseases," he said. "There will be challenges, but I don't see why it can't happen. This isn't science fiction."
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