Chondroprotective role of histone deacetylase 4 in early-stage of temporomandibular joint osteoarthritis in male rats.

OBJECTIVE: The aim of this study was to investigate the expression and role of histone deacetylase 4 (Hdac4) in temporomandibular joint osteoarthritis in rats. DESIGN: A model of temporomandibular joint (TMJ) osteoarthritis was established by partial discectomy in male rats. In the early stage of TMJ osteoarthritis, small interfering-HDAC4 (si-HDAC4) with adeno-associated virus was injected into the rat articular cavity to knockdown the expression of Hdac4 in TMJ. And an adenoviral vector was used to transfer Hdac4 into the rat articular cavity to increase the level of Hdac4 in TMJ. Subsequently, the pathological changes and stages of condylar cartilage were examined histopathologically at different time points after injection respectively, and the microstructure of TMJ subchondral bone was evaluated using micro computed tomography. RESULTS: Hdac4 expression in condylar cartilage was upregulated in the early-stage of TMJ osteoarthritis, but decreased in the mid to late-stage. Knockdown of Hdac4 expression in the early-stage of TMJ osteoarthritis accelerated the destruction of condylar cartilage in vivo, while overexpression of Hdac4 reduced the destruction of cartilage in the late-stage. Meanwhile, on micro computed tomography, the microstructure of subchondral bone in TMJ showed that overexpression of Hdac4 led to a decrease in incidence of bone sclerosis. CONCLUSIONS: Our results suggested that Hdac4 has a certain chondroprotective effect in the development of TMJ osteoarthritis.