CORRELATION BETWEEN Β - CATENIN SIGNALING PATHWAY AND CHONDROCYTE APOPTOSIS AND OSTEOARTHRITIS IN SOST TG MICE

Anyu Luo^*, Hanlin Liu, Dong Chen, Xiaofei Xie

Department of Orthopaedics, Hanyang Hospital affiliated to Wuhan Science and Technology University, 430050

Objective: To investigate the relationship between the β-catenin signalling pathway, chondrocyte apoptosis and osteoarthritis in osteosclerotin (SOST) transgene (TG) mice.

Methods: Sixty specific pathogen–free healthy SOST TG mice were selected and divided into normal, moderate osteoarthritis (moderate group) and severe osteoarthritis groups (severe group) according to the modified Mankin articular cartilage pathological score. The changes in articular cartilage, chondrocyte pathological changes, chondrocyte apoptosis and β-catenin expression in chondrocytes were compared.

Results: Compared with the normal group, the Mankin score in the moderate and severe groups was increased significantly, and with the aggravation of osteoarthritis, the Mankin score increased gradually (P<0.01). In the normal group, the articular cartilage surface was smooth, with normal thickness, uniform safranine O staining and there was no loss of proteoglycan in the femoral condyle and tibial plateau. In the moderate group, the articular surface was abraded and proteoglycan was lost, but it was lighter than that in the normal group. In the severe group, the non-calcified cartilage in the tibial plateau and femoral condyle essentially disappeared, and there was severe loss of proteoglycan. In the normal group, the surface of chondrocytes was complete, the structure was clear, and the arrangement was orderly. In the moderate group, the chondrocytes were hypertrophic, and the arrangement was disordered. In the severe group, the chondrocyte surfaces were damaged to varying degrees, and the chondrocytes were significantly reduced. Compared with the normal group, the positive rate of chondrocyte apoptosis in the moderate and severe groups was significantly higher (P<0.01). The normal group had fewer β-catenin staining–positive cells. In the moderate group, the β-catenin staining–positive cells were more concentrated on the cartilage surface. In the severe group, there were numerous β-catenin staining–positive cells on the surface and deep cartilage. Compared with the normal group, the moderate and severe groups had significantly increased β-catenin–positive cells (P<0.01). Pearson correlation analysis showed that the β-catenin expression level and the positive rate of chondrocyte apoptosis correlated positively with Mankin score. A higher Mankin score indicated a higher β-catenin expression level and positive rate of chondrocyte apoptosis (P<0.05).

Conclusion: The expression level of β-catenin and the positive rate of chondrocyte apoptosis in patients with osteoarthritis are significantly higher than those in normal people, and participate in the development of osteoarthritis.