Some joints may be primed for rheumatoid arthritis before birth

Researchers at the Kennedy Institute have found evidence that some joints may be more vulnerable to inflammatory arthritis before birth. The discovery could help explain a long-standing puzzle in rheumatoid arthritis: why the disease repeatedly attacks certain joints while leaving others largely untouched.

The study, "The embryonic origins of site-specific arthritis," was published in Nature Immunology . It suggests that the answer may depend not only on the immune system, but also on biological differences built into individual joints during development.

Rheumatoid arthritis is an autoimmune condition in which the immune system attacks the synovium, the tissue that lines the joints. This produces pain, swelling and stiffness and, over time, can damage cartilage, bone and surrounding tissues.

To investigate why rheumatoid arthritis favors particular joints, the researchers examined two types of finger joints with very different patterns of disease susceptibility.