The role and significance of the transforming growth factor-β signaling pathway in the model of steroid-induced osteonecrosis of the femoral head in young rabbits / 中华实用儿科临床杂志

ABSTRACT

Objective:To explore the relationship between the transforming growth factor-β (TGF-β) signaling pathway and steroid-induced osteonecrosis of the femoral head in young rabbits.Methods:Sixty 8-week-old rabbits weighing 1.5-2.0 kg were randomly divided into steroid injection group (48 cases) and control group (12 cases). Rabbits in the former group were injected with Prednisolone Acetate 7.5 mg/kg into bilateral gluteal muscles twice a week for 8 weeks, and those with successful modeling were included in the disease group; otherwise, they were included in the non-disease group.Rabbits in control group were similarly injected with the same volume of 9 g/L saline.Penicillin sodium 50 000 U/rabbit was injected once a week for preventing infection.After 8 weeks of injection, CT was performed in all the experimental animals.They were then sacrificed for collecting bilateral femoral heads.Expression levels of TGF-β1, TGF-β2, Smad2 and Smad3 in the femoral head were detected by enzyme linked immunosorbent assay (ELISA), and the mRNA level of Runx2 in the femoral head was detected by quantitative real-time PCR (qPCR), the expression differences of related factors in each group were compared.Results:In steroid injection group (48 cases), 6 rabbits were sacrificed, and 32 survived, involving 6/32 cases (18.75%) experimental animals with positive avascular necrosis (disease group), and 26 negative ones (non-disease group). ELISA data showed that expression levels of TGF-β1 in control group, non-disease group and disease group were (77.12±14.62) ng/L, (90.17±11.90) ng/L and (126.14±25.66) ng/L, respectively ( t=3.35, 4.24, all P<0.05). The expression levels of TGF-β2 in control group, non-disease group and disease group were (74.54±7.63) ng/L, (89.24±9.51) ng/L and (109.74±16.45) ng/L, respectively ( t=4.12, 5.65, all P<0.01). The expression levels of Smad2 in control group, non-disease group and disease group were (17.74±2.72) μg/L, (23.82±3.58) μg/L and (31.28±3.88) μg/L, respectively ( t= 4.54, 7.99, all P<0.01). The expression levels of Smad3 in control group, non-disease group and disease group were (1.76±0.52) μg/L, (2.39±0.45) μg/L and (3.53±0.47) μg/L, respectively ( t=5.60, 6.71, all P<0.01). qPCR data showed that the mRNA levels of Runx2 in control group, non-disease group and disease group were 1.02±0.17, 1.27±0.14, and 1.72±0.11, respectively ( t=7.60, 8.91, all P<0.01). Conclusions:TGF-β is up-regulated in the model of steroid-induced osteonecrosis of the femoral head in young rabbits, which stimulates the proliferation and differentiation of osteoblasts and osteoclasts, and triggers the process of bone remodeling.The TGF-β signaling pathway involved in the repair of necrotic bone.