Effect of high-intensity exercise on interleukin-15 expression in rabbit synovia

The objective of this study was to examine the effect of high-intensity exercise on interleukin-15 (IL-15) expression in rabbit synovia. We utilized 24 New Zealand white rabbits, which were randomly divided equally into high-intensity exercise and control groups. The former were forced to run for 60 min/day over 4 weeks at the speed of 30 m/min. The histological changes of cartilage and knee joint synovia were investigated with hematoxylin and eosin staining. Immunohistochemistry and enzyme-linked immunosorbent assays were performed to measure IL-15 expression. From these analyses, we identified knee articular cartilage damage and synovitis in the high-intensity exercise group. This group also exhibited higher IL-15 expression in their synovial fluid and tissues than was observed in the control group (P < 0.05). These results suggested that high-intensity exercise might lead to synovitis and articular cartilage damage, and that IL-15 overexpression in synovia might be associated with post-traumatic osteoarthritis.