Objective: To explore the mechanism of Bushen Qiangji Granule(补肾强脊颗粒, BSQJ) in restraining the osteogenic differentiation of ankylosing spondylitis(AS) fibroblasts. Methods: Hip joint capsules were obtained from AS patients(n=10) receiving total hip replacement and healthy hip joint capsules from patients with hip fracture(n=10) receiving surgery as a control. Finite fibroblast lines were established from these tissue samples to observe the effect of BSQJ on suppressing osteogenic differentiation of fibroblasts. The expression of osteogenic marker gene corebinding factor a1(Cbfa1) and Smad family proteins were examined by Western blot and real-time quantitative polymerase chain reaction(q PCR). Results: The m RNA expression level of Cbfa1 was significantly higher in AS fibroblasts than that in normal fibroblasts and the expression of p Smad1, p Smad5, Smad4 and Cbfa1 in AS fibroblasts was also higher, demonstrating the activation of the BMP/Smads signal pathway in AS fibroblasts. BSQJ-medicated serum not only restrained the m RNA and protein expression levels of Cbfa1 and inhibited protein expression level of Smad4 but also decreased the expression quantities of p Smad1 and p Smad5. Conclusions: BSQJ can inhibit osteogenic differentiation of AS fibroblasts in vitro by suppressing the activation of the BMP/Smads signal pathway. This may be the important molecular mechanism of BSQJ in regulating AS ossification.
