Effects of osteopontin on the expression of IL-6 and IL-8 inflammatory factors in human knee osteoarthritis chondrocytes

Y. Yang, S.-G. Gao, F.-J. Zhang, W. Luo, J.-X. Xue, G.-H. Lei

Department of Orthopedics, XiangYa Hospital, Central South University, Changsha, China. lgh9640@sina.com

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• Orthopedics

OBJECTIVE: Osteoarthritis (OA) is a chronic musculoskeletal disease characterized by progressive destruction of articular cartilage, OA lead to chronic pain and functional restrictions in affected joints. The present study was to investigate the role of osteopontin (OPN) in the athogenesis of OA through studying the effect of OPN on expression of IL-6 and IL-8 inflammatory factors in human OA chondrocytes.

PATIENTS AND METHODS: One-step type II collagenase digestive method was used to isolate OA chondrocytes from sectional cartilage specimens of 16 primary knee OA patients received total knee replacement surgery. Synchronized first-generation chondrocytes were then treated with OPN (100 ng/ml or 1 µg/mL). The changes in cell morphology of OA chondrocytes were analyzed before and after treated with OPN; and the expression levels of IL-6 and IL-8 were evaluated by real-time q-PCR.

RESULTS: Chondrocytes were successfully isolated from human OA knee cartilage, and the viability of isolated chondrocytes was 92.11±3.13%. Adherent chondrocytes formed clusters of irregular polygonal shape with intercellular pseudopodia extension. After OPN treatment, cells became fusiform or irregularly shaped, and the number of intercellular pseudopodia decreased significantly. The mRNA expression of IL-6 increased to 1.83 times at 0.1 µg/ml of OPN and 3.1 times at the dose of 1 µg/ml; the expression of IL-8 increased to 1.57 and 3.27 times at the dose of 0.1 µg/ml and 1 µg/ml respectively.

CONCLUSIONS: OPN could up-regulate expression of IL-6 and IL-8 cytokines in human OA chondrocytes, and the expression increased with the increasing concentration of OPN, which might be one of the potential mechanisms of OPN in the development of OA.

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