Rheumatoid arthritis is a progressive disease that causes joint inflammation and destruction. Researchers say initially the disease starts out in just a few joints but soon spreads to other joints in the body.
Until now, the method of how the disease spreads from joint to joint was unknown. But a study in Nature Medicine suggests that cells called synovial fibroblasts may be to blame.
The cells, which are present in lining of the joints, are already implicated in the cartilage destruction associated with rheumatoid arthritis.
In the study, researchers implanted healthy human cartilage tissue plus synovial fibroblasts from people with rheumatoid arthritis into one side of lab mice. The opposite side was injected with healthy cartilage without the diseased fibroblasts.
After 60 days, the results showed that synovial fibroblasts had actively moved from one side of the mice's body to the other via blood vessels and were already causing cartilage damage.
Researcher Stephanie Lefevre of the department of internal medicine and rheumatology at the Kerckhoff-Clinic, Bad Nauheim, Germany, and colleagues say the study supports the notion that the spread of rheumatoid arthritis between joints is at least partially due to the migration of affected synovial fibroblasts through the bloodstream.