A mechanism that accounts for the spreading of arthritis between joints is presented in a study published online in this week's Nature Medicine.
Rheumatoid arthritis starts in a few joints but subsequently spreads to affect most joints, though the pathways that account for this progression were previously unknown. Elena Neumann and her colleagues tested whether synovial fibroblasts ― cells present in the fluid that bathes the joints and also implicated in cartilage destruction in arthritis patients ― could spread the disease.
Using mice, the scientists implanted healthy human cartilage plus synovial fibroblasts from arthritis patients into one side of their bodies, and healthy cartilage without the fibroblasts into the opposite side. Synovial fibroblasts actively moved from one side to the other via blood vessels, leading to marked cartilage destruction.