Why is arthritis likely to occur repeatedly in the same place?

One of the symptoms of rheumatoid arthritis and related diseases is 'arthritis, ' which causes swelling and pain in the joints. And, for example, arthritis that started in the right knee is said to have a high possibility of re-inflammation from the same right knee, even if it continues to be in remission for many years. A new study on why arthritis is more likely to recur in the same place has been published by a joint research team at Boston Children's Hospital and Brigham & Women's Hospital.

Arthritis flares mediated by tissue-resident memory T cells in the joint: Cell Reports
https://www.cell.com/cell-reports/fulltext/S2211-1247(21)01372-3

Thanks to Mice, We May Know Why Arthritis Keeps Flaring Up in The Same Joints
https://www.sciencealert.com/immune-system-memory-might-explain-why-arthritis-flares-up-the-same-joints-twice

'Arthritis occurs in joints that have been overwhelmingly previously affected,' said Peter Nigrovic, director of immunology at Boston Children's Hospital. It seems that I remember. '

Nigrovic suspected that this inflamed memory might be sleeping in the immune cells 'memory T cells ' in the synovium inside the joints. According to Nigrovic, memory T cells remain in the joints even after the arthritis has subsided, triggering a recurrence of inflammation. In fact, it is known that skin psoriasis and hypersensitivity are likely to recur in the same place due to memory T cells, and Mr. Nigrovic thinks that the same reasoning as this skin inflammation can be said for joints. That's why.

A research team led by Nigrovic has shown three models of mice suffering from inflammatory arthritis. Two of these models were triggered by chemicals, and the third model was triggered by a genetic deficiency in a protein that blocks pro-inflammatory cytokines.

In both models, it was confirmed that when inflammation occurs, memory T cells resident in joints assemble other immune cells, and after that, arthritis is caused only in specific joints. Then, it was found that the recurrence of arthritis was suppressed by removing these memory T cells. In other words, the location of inflammation was remembered by memory T cells.

'Currently, treatment for rheumatoid arthritis must continue for life. Many patients have been successful in controlling their symptoms, but there is no cure. This discovery is a new treatment. We believe it will pave the way for us. '