ABSTRACT
Objective:To investigate the effect of modified citrus pectin (MCP) on the glucose metabolism of rabbit articular chondrocytes.Methods:The third generation (P3) rabbit knee chondrocytes were extracted and cultured with 0 μg/ml (MCP0, control group) and 500 μg/ml of MCP (MCP500) for 3 days. Chondrocytes (P2-P7)were cultured continuously, and each generation of chondrocytes was treated with MCP0 and MCP500 medium for 3 days. Chondrocytes were treated with interleukin-1β (IL-1β) for 1 day and then treated with MCP0 and MCP500 medium for 3 days, respectively. Chondrocytes were treated with 2-deoxy-glucose (2DG) for 1 day and then treated with MCP0 and MCP500 medium for 3 days, respectively. After three days of culture, the proliferation of chondrocytes was calculated by CCK-8. Glucose uptake activity and lactate production of chondrocytes were measured by glucose and lactate detection kits. The synthesis of type Ⅱ collagen (COL2A1) in sequential chondrocytes was investigated by immunofluorescence staining. The gene expression of COL2A1, proteoglycan ( ACAN), SOX9, hypoxia-inducible factor-1α ( HIF-1α), glucose transporter-1 ( Glut-1), pyruvate kinase M2 ( PKM2), lactate dehydrogenase-A ( LDHA) and glucose transporter-1 ( Glut-3) were further detected by RT-qPCR. Results:Compared with the control group, MCP treatment could increase the glucose uptake activity and lactate production of chondrocytes, and enhance the gene expression ability of HIF-1α, Glut-1, PKM2 and ACAN. Besides, MCP treatment could stimulate chondrocyte proliferation, maintain chondrocyte phenotype, increase lactate production, and upregulate the expression of COL2A1, ACAN, SOX9, HIF-1α, Glut-1, PKM2 and LDHA. After the treatment with IL-1β, MCP treatment could increase glucose uptake activity and upregulate the expression of COL2A1, ACAN, HIF-1α and Glut-1. After treatment with 2DG, MCP treatment could increase glucose uptake activity and upregulate the expression of SOX9, HIF-1α, PKM2 and Glut-3 genes. Conclusions:MCP can enhance the glucose uptake capacity of chondrocytes and increase the level of chondrocyte glycolytic metabolism.
ABSTRACT
Objective:To study the effects of modified citrus pectin (MCP) on the viability and gene expressions of synovial fibroblasts (SF) as well as SF treated by galectin-3 (Gal-3).Methods:Rabbit SF was isolated and cultured in vitro. Then SF was treated with different concentrations of MCP (0, 250, 500, and 750 mg/L). In addition, SF was further treated with the same different concentrations of MCP after treatment with 10 μg/ml Gal-3 for 24 h. The viability of SF was detected by CCK-8 on the first, third, and fifth day after treatment. The mRNA expression of transforming growth factor-β1 (TGF-β1), type I collagen (COL1A2), and Gal-3 in SF was detected by real-time quantitative PCR. The synthesis of type I collagen in SF was investigated by immunofluorescence staining. Results:MCP, especially at a concentration of 500 mg/L can inhibit the proliferation of SF significantly (all P < 0.05) on the first, third, and fifth day after treatment. Compared with the control group, MCP at different concentrations induced different gene expression profiles. In particular, MCP at high concentrations can upregulate the expression of TGF-β1, COL1A2 and Gal-3 in SF. However, MCP shows no significant effect on the synthesis of type I collagen in SF. MCP can down-regulate the expression of TGF-β1, COL1A2, and significantly reduce the synthesis of type I collagen in SF after Gal-3 treatment. Particularly, the effect of MCP at a concentration of 500 mg/L on inhibiting the expression of TGF-β1, COL1A2, and Gal-3 in SF is significant. Conclusions:MCP can inhibit the excessive proliferation of SF and regulate gene expression in SF.