Effects of Leptin on Differentiation and Proliferation of Chondrocytes

Abstract

Osteoarthritis (OA) is a degenerative joint disease which is one of the most frequent and disabling diseases encountered in elderly individuals. Leptin was unregulated significantly in OA cartilage and was regarded as a metabolic link between obesity and OA. In this study, we evaluated the effect of 10 or 100 ng/ml leptin on the ATDC5 cells. Results revealed that 10 or 100 ng/ml of leptin significantly decrease the expression of aggrecan and type II collagen mRNA and protein levels compare to control (0 ng/ml). Interestingly, sex determining region Y-box 9 mRNA and protein was down-regulated by leptin. Collagen X is a specific marker of hypertrophic and calcified chondrocyte. It has been noted that both mRNA and protein of Collagen X was significantly upregulated with leptin treatment. Meanwhile, Alcian Blue staining indicated that leptin reduces the synthesis of proteoglycan. Alizarin red S staining and alkaline phosphatase activity detection demonstrated that leptin induced cartilage nodules formation and mineralization in a dose dependent manner. We conclude that leptin slightly inhibits the proliferation of ATDC5 cells and affects cartilage-specifically marked proteins and genes. In summary, it has been suggested that leptin stimulate hypertrophic differentiation of ATDC5 cells.