When joints flare-up in people with rheumatoid arthritis and related diseases, the joints involved are often the same as those affected before.
For example, if arthritis started in the right knee, it is much more likely to flare there than in the left knee, even if arthritis had been in remission for years.
As a result, each patient develops a highly individual disease pattern. But why this happens has remained a mystery.
In a new study from Boston Children’s Hospital, researchers found where that memory is housed: in a type of immune cell called a tissue-resident memory T cell.
Specifically, these T cells reside in the synovium, the tissue that lines the inside of the capsule surrounding the joint.
They showed that these T cells anchor themselves in the joints and stick around indefinitely after the flare is over, waiting for another trigger. If these cells are deleted, arthritis flares stop.
In the study, the team demonstrated this phenomenon in three separate mouse models of inflammatory arthritis.
Once activated, resident memory T cells in the joints rallied other immune cells, leading to an arthritis flare limited to specific joints. Elimination of these T cells blocked additional flares from occurring.
The team believes the findings apply to other types of autoimmune arthritis, including juvenile idiopathic arthritis.
If you care about arthritis, please read studies about a new way to strongly reduce pain and inflammation in arthritis and findings of this arthritis drug could reduce death rate in COVID-19.
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The study is published in Cell Reports. One author of the study is Peter Nigrovic, MD.
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