Abstract| Volume 25, SUPPLEMENT 1, S157, April 2017

Spatial and temporal expression pattern of hmgb2 in rabbit condylar cartilage following anterior disc displacement

      Purpose: The chromatin protein HMGB2 plays important roles in development, remodeling and disruption of the articular cartilage. The objective of present study was to investigate whether the expression of HMGB2 in the condylar cartilage was correlated to the continuing forward mandibular positioning (FMP), and explore its potential relationship with β-catenin pathway.
      Methods: Fourty-four healthy adult Japanese white rabbits were used in this experiment. The right tempromandibular joints (TMJ) of rabbits were subjected to surgical and sham surgical operation of anterior disc displacement (ADD) (N=8). The TMJ condyles of rabbits were collected and fixed at 1-, 2-, 4-, and 8- weeks after the surgery. Histological micrographs of the condyle cartilage were mearsured by HE staining. The distribution and expression of HMGB2, Col-II, MMP1, MMP13 and β-catenin were evaluated through immunohistochemical staining.
      Results: Histological results by HE staining showed that the condyle cartilage turned thinner as well as disordered cell arrangement in cartilage with ADD. The expression of HMGB2 chiefly distributed in fibrous layer and proliferative layer of normal condylar cartilage. After ADD treatment, expression of HMGB2 and β-catenin enhanced at the 1 week ADD, and subsequently decreased at 2 and 4 weeks. COL-II and MMP13 expression also increased at the 1–2 weeks after ADD, suggesting osteoarthritis may occur in condylar cartilage. Most of the cartilages were repaired and chondrocytes were arranged in order at 8 weeks, suggesting spontaneous remodeling of condylar cartilage after external force loading.
      Conclusions: These findings suggest that HMGB2 may play important roles in chondrocytes following exposure to mechanical loading, which may involve in the pathogenesis of osteoarthritis.