Patient Research Tips: Gut Bacteria Stimulate Autoimmunity in Rheumatoid Arthritis|Science and Translational Medicine

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A new study involving mice and 6 patients with rheumatoid arthritis or at high risk showed that a bacterium found in the gut microbiome may contribute to the formation
of harmful autoimmune antibodies in the early stages of rheumatoid arthritis.

The findings point to a link between disturbances in the microbiome and the debilitating disease, whose triggers remain largely a mystery
to scientists.

Rheumatoid arthritis is one of the most prevalent autoimmune diseases, and more research is needed to understand its causes and develop new treatments
.
Some researchers hypothesize that environmental influences, such as microbes, can trigger the disease by generating a sustained local immune response, which translates into systemic autoimmunity
over time.

In the study, Meagan Chriswell and colleagues analyzed
IgG and IgA autoantibodies from blood samples from 4 people at risk of developing rheumatoid arthritis and 2 patients in the early stages of rheumatoid arthritis.

They found that these antibodies not only respond to rheumatoid arthritis antigens, but also gut bacteria from the Lachnospiraceae and Ruminococcaceae families — particularly those from rare micrococci species (Subdoligranulum) bacteria — reacting
.

By studying 50 bacterial strains isolated from a patient, the team found one strain
that binds to monoclonal autoantibodies and activates T cells.
When mice formed colonies of this strain of the genus Rare Micrococcus, these mice developed symptoms of rheumatoid arthritis (such as joint inflammation and swollen paws), suggesting that this isolate may be driving the emergence
of autoantibodies in the disease.

Rabi Upadhyay and Dan Littman say in a related Focus article: "By identifying specific gut microbiota that may trigger an initial local immune response, and by conducting clinical trials that may eliminate these bacteria in high-risk individuals, rheumatologists may finally have a chance to reverse or prevent the disease from occurring
.
" ”