Achyranthes bidentate saponins protect rat articular chondrocytes against interleukin-1β-induced inflammation and apoptosis in vitro

Achyranthes bidentate Blume (Niuxi) is often employed for treatment of arthritis in Traditional Chinese Medicine and possesses anti-inflammatory properties. Phytochemical and pharmacological studies proved the oleanane-type saponins to be the main bioactive principles. In the present study, protective effects of A. bidentata saponins (ABS) on inflammation and apoptosis in interleukine-1β (IL-1β)-induced chondrocytes were investigated. Rat chondrocytes were pretreated with ABS at 3 μg/mL, 10 μg/mL, and 30 μg/mL, and subsequently stimulated with IL-1β (10 ng/mL). Methylthiazolyldiphenyl-tetrazolium bromide assay and annexin V/propidium iodide dual staining demonstrated that ABS could protect IL-1β-induced chondrocyte injury. ABS suppressed IL-1β-induced apoptosis by suppressing the activation of caspase-3, inhibiting levels of proapoptotic proteins Bax and Bad, decreasing p53 protein phosphorylation, and promoting the expression of antiapoptotic protein Bcl-xL and proliferating cell nuclear antigen. IL-1β-induced inflammation and matrix degradation were also alleviated by ABS through the downregulation of the expressions of matrix metalloproteinases 3 and 9 and cyclooxygenase-2. Moreover, ABS inhibited IL-1β-induced nuclear factor κB activation in rat chondrocytes. We demonstrated, for the first time, the protective effects of ABS on IL-1β-stimulated chondrocytes and their molecular mechanisms. Thus, it is suggested that ABS might be a potential drug in the treatment of osteoarthritis.