Cyclooxygenase-2 inhibitor rofecoxib prevents chondrocytes against hypertrophy via Wnt/ß-catenin pathway.

Previous reports indicated that specific cyclooxygenase-2 (COX-2) inhibitor suppresses osteoarthritis (OA). This study aimed to further explore the possible mechanism of Rofecoxib as a COX-2 inhibitor on the inhibition of chondrocyte (CH) hypertrophic development and tested the optimal treatment of Rofecoxib on CH. Basically, IL-1ß was used as a stimulus to establish a degenerated CH model. Immunofluorescence, Western blot, and RT-PCR were performed to determine the gene expression of Axin2, ß-catenin, GSK3ß, collagen X, collagen II, COX-2, PGE-2, SOX-9, Runx-2, and MMP- 13 expression. Cell Counting Kit (CCK-8) assay was used to analyze the viability of CHs. The data indicated that Rofecoxib significantly inhibited COX-2 expression and had less harmful effects on CH viability. Rofecoxib reversed the IL-1ß-induced upregulation of collagen X, COX-2, PGE-2, Runx-2, and MMP-13 expression, and promoted the viability of collagen II, SOX-9 expression of CHs. Furthermore, Rofecoxib suppressed Axin2, ß-catenin, and GSK3ß expression of the Wnt pathway, which was activated by IL-1ß or human recombinant Wnt-1 protein treatment. Therefore, Rofecoxib is an effective COX-2 inhibitor that protects CHs from hypertrophy by suppression of the Wnt/ß-catenin pathway.

Protective effect of vitamin E on age-related alterations of Kupffer cell energy metabolism.

AIM: To investigate the mechanism of age-related reduction of Kupffer cell (KC) phagocytic capacity and the protective management. METHODS: Using rhodamine 123 fluorescence density and rate of glucose utilization as parameters, we measured the mitochondrial energy metabolism status in vitro and the glucose utilization capacity of isolated rat liver Kupffer cells (KCs) from rats of various ages (6 mo, 12 mo, 18 mo and 24 mo) and the effect of vitamin E (VE) pretreatment (500 mg/kg/wk × 13 wk). RESULTS: The rate of KC glucose utilization and the rhodamine fluorescence density of KC mitochondria of 18 mo-old untreated rats (NVEG) were significantly lower than that of 6 mo-old NVEG by 19.3% (4.0 nmol·h ± 0.4 nmol·h(-1) 10.6 cells(-1) vs 5.7 nmol·h ± 0.6 nmol·h(-1) 10(6) cells(-1), P < 0.05) and 19.5% (80.5 ± 6.3 vs 100.0 ± 4.7, P < 0.01) respectively; Rate of KC glucose utilization and the rhodamine fluorescence density of KC mitochondria of 6 mo-old rats were also lower than the 24 mo-old NVEG by 35.1% (3.7 nmol·h ± 0.6 nmol·h(-1)10(6) cells(-1) vs 5.7 nmol·h ± 0.6 nmol·h(-1) 10(6) cells(-1), P < 0.01) and 32.1% (67.9 ± 7.4 vs 100.0 ± 4.7, P < 0.01) respectively. The two parameters of 18 mo-old VE pretreated rats (VEG) were significantly higher than those of 18 mo-old NVEG, and statistically comparable to those of 6 mo-old VEG. The two parameters of the 24 mo-old VEG were significantly higher in comparison with those of 24 mo-old NVEG, but still significantly lower than those of 6 mo-old VEG. CONCLUSION: Aging has a significantly negative effect on KC energy metabolism, which can be alleviated by VE pretreatment.