The Expression of Netrin-1 in the Osteoarthritic Temporomandibular Joint

Abstract

Subchondral bone degeneration is the main pathological change during temporomandibular joint (TMJ) osteoarthritis (OA) development. Netrin-1, an axon-guiding factor, might play roles in OA development and pain. The purpose of this study was to investigate the expression of Netrin-1 in TMJ OA and its possible role in the progression of TMJ OA and pain. The content of Netrin-1 in the synovial fluid of temporomandibular joint disorders (TMDs) patients was detected by ELISA. After injection of MIA into the TMJ animal model, hematoxylin & eosin (H&E) staining, toluidine blue (TB) staining and micro-CT were performed to detect the change of TMJ. Netrin-1 expression in the condyle was detected by immunohistochemical (IHC) staining. The pain experience was examined by the von Frey test in animal model. The concentration of Netrin-1 increased in the synovial fluid of TMJ OA patients with the VAS scores increased. In the TMJ OA model, the structural disorder of subchondral bone was the most obvious at the 2nd week. In addition, the head withdrawal threshold (HWT) was significantly decreased in the TMJ OA model. Netrin-1 expression increased in the subchondral bone at the 2nd week after MIA injection in the mouse TMJ. Cultivate raw264.7 cells and induce them to differentiate into osteoclasts. Netrin-1 and its receptor Unc5B are detected to be expressed on the osteoclast membrane. Thus, Netrin-1 might be a regulator during degeneration and pain in the process of TMJ OA.