Colchicine protects against cartilage degeneration by inhibiting MMP13 expression via PLC-γ1 phosphorylation.

OBJECTIVE: Low molecular weight compounds that reduce the expression of MMP13 at the mRNA level might serve as disease-modifying osteoarthritis (OA) drugs (DMOADs). The objective of this study was to identify a candidate DMOAD that targets MMP13 expression. DESIGN: High-throughput screening was performed to identify compounds that suppress inflammatory cytokine-induced MMP13 expression. Ingenuity pathway analysis (IPA) using isobaric tags for relative and absolute quantification (iTRAQ)-based proteomic analysis was conducted to identify signaling pathways related to cytokines. MMP13 expression in chondrocytes was evaluated through RT-qPCR and western blotting analyses. Additionally, 10-week-old mice were subjected to destabilization of the medial meniscus (DMM) surgery to induce OA and were sacrificed 12 weeks post-surgery for pathological examination. OA was evaluated using the OARSI scoring system. RESULTS: Colchicine was identified as a DMOAD candidate as it inhibited inflammatory cytokine-induced MMP13 expression in vitro, and the colchicine-administered mice with DMM presented significantly lower OARSI scores (adjusted P: 0.0242, mean difference: 1.6, 95% confidence interval (CI) of difference: 0.1651-3.035) and significantly lower synovial membrane inflammation scores (adjusted P: 0.0243, mean difference: 0.6, 95% CI of difference: 0.06158-1.138) than mice with DMM. IPA further revealed that components of the Rho signaling pathways are regulated by cytokines and colchicine. IL-1ß and TNF-α activate RAC1 and SRC signals, respectively, leading to the phosphorylation of PLC-γ1 and synergistic induction of MMP13 expression. Most notably, colchicine abrogates inflammatory cytokine-induced phosphorylation of PLC-γ1, leading to the induction of MMP13 expression. CONCLUSIONS: Colchicine is a potential DMOAD candidate that inhibits MMP13 expression and consequent cartilage degradation by disrupting the SRC/RAC1-phospho-PLCγ1-Ca2+ signaling pathway.

The influence of protein and/or energy deficiency on the growth of long bone in rats.

The effects of protein and/or energy deficiency on long bone growth were studied using rats of an average weight 100g. Four groups of Wistar rats were respectively fed on a normal diet, a low-energy diet, a low protein-diet, and a low-protein and low-energy diet for 45 days. Both energy and protein deficiency restricted gains of body weight and femur length and the activity of alkaline phosphatase in the tibia to the same extent. The epiphyseal growth plates of the femur in protein-deficient rats were as thin as those in energy-deficient rats. On the other hand, femur width and activity of acid phosphatase in the tibia were lower in protein-deficient animals than those in energy-deficient ones. Serum calcium concentrations and calcium content of bone were the same among all groups.

Suppressive effect of calcitonin on intestinal absorption of calcium and phosphorus in sheep.

This study was carried out to determine the effect of calcitonin on calcium and phosphorus absorption in sheep. Six sheep, which were prepared with a carotid loop and a portal venous catheter, were used. Thyroidectomized sheep were injected intramuscularly with porcine calcitonin at feeding time. Serum calcium concentrations did not change in intact or thyroidectomized sheep after feeding but calcium venoarterial blood differences in thyroidectomized sheep were higher than in intact sheep 8 h after feeding. Serum calcium concentrations and calcium veno-arterial blood differences were decreased by calcitonin injection into thyroidectomized sheep. Calcitonin injection also reduced the serum phosphorus concentrations. Phosphorus veno-arterial blood differences in thyroidectomized sheep were much less than in intact sheep before feeding although the blood differences were not affected by calcitonin injection in thyroidectomized sheep. The results indicated that calcitonin decreased calcium absorption, which caused a reduction in the serum calcium concentrations, and that calcitonin injection did not affect phosphorus absorption in thyroidectomized sheep.