ABSTRACT
Objective To investigate the effects of vitamin D on synthesis and secretion of lubricin in chondrocytes at the cellular level. Methods Rat articular chondrocytes were stimulated by TNF-α. Normal and inflammatory chondrocytes were treated by different doses of vitamin D respectively. ELISA and Western Blot were used to detect the secretion of lubricin in the supernatant and the synthesis level in the cells. Results TNF-α significantly reduced the activity of both normal chondrocytes and chondrocytes in inflammatory state. TNF-α also significantly reduced the expression of lubricin in the cells and supernatant. 1α,25(OH)2D3 increased the activity of both normal chondrocytes and chondrocytes in inflammatory state. 1α,25(OH)2D3 significantly elevated the secretion and expression of supernatant and intracellular lubricin only in chondrocytes stimulated by TNF-α in a dose-dependent manner, but not in normal chondrocytes. Conclusions Vitamin D can promote the secretion and expression of lubricin in inflammatory state chondrocytes, which may act as one of the mechanisms of vitamin D protecting the cartilage surface in osteoarthritis.
ABSTRACT
Objective To investigate the effects of vitamin D on synthesis and secretion of lubricin in chondrocytes at the cellular level. Methods Rat articular chondrocytes were stimulated by TNF-α. Normal and inflammatory chondrocytes were treated by different doses of vitamin D respectively. ELISA and Western Blot were used to detect the secretion of lubricin in the supernatant and the synthesis level in the cells. Results TNF-α significantly reduced the activity of both normal chondrocytes and chondrocytes in inflammatory state. TNF-α also significantly reduced the expression of lubricin in the cells and supernatant. 1α,25(OH)2D3 increased the activity of both normal chondrocytes and chondrocytes in inflammatory state. 1α,25(OH)2D3 significantly elevated the secretion and expression of supernatant and intracellular lubricin only in chondrocytes stimulated by TNF-α in a dose-dependent manner, but not in normal chondrocytes. Conclusions Vitamin D can promote the secretion and expression of lubricin in inflammatory state chondrocytes, which may act as one of the mechanisms of vitamin D protecting the cartilage surface in osteoarthritis.