Dendritic cells (DCs) are critical initiators of immune responses, however, its distribution and role in osteoarthritis (OA) remains largely unknown. This study is to investigate the distribution of DCs in the rabbits' synovium of experimental OA.
Model of OA was established by excising the medial meniscus of both hind knees in New Zealand white rabbits. The grades of synovium and articular cartilage were assessed and scored by hematoxylin eosin stain after 2, 4, 8, and 12 weeks of operation. The distribution of DCs was investigated by immunohistochemistry staining in the synovium from OA rabbits. The levels of IL-1β and TNF-α in synovial fluid were measured by ELISA kits.
Molecular markers for DCs, such as DC-LAMP, CD80, CD83, and CD86 were detected in lymphoid aggregations and perivenular infiltration areas in the synovium from OA rabbits. Large numbers of DCs were observed in the synovium in the early stages (2 or 4 weeks) after operation. The number of DCs was significantly increased with the progression of inflammatory grade in synovium in the same early stages. Expression of IL-1β and TNF-α were also increased in the early stages, then decreased with the inflammatory regression in synovium.
The data from this study strongly suggested that DCs may play a key role, at least in part, in inflammation of the OA pathogenesis, especially in the early stages of OA.