Long term intermittent compression of articular cartilage attenuates cartilage degradation

Abstract

accompanied by reduced joint damage and pain. The aim of the present study was to analyze downstream mediators of CCL2/CCR2 signaling in human articular chondrocytes that lead to the activation of genes involved in cartilage degradation. Methods: We used human articular chondrocytes from normal cartilage obtained from tissue donors to determine the signaling pathways activated by CCL2 (through CCR2) that lead to production of MMPs. Human chondrocyte primary cultures were treated with or without recombinant CCL2 (20ng/ml) in serum free medium for 5, 10 and 15 minutes. Cell lysates were collected and subjected to Immunoblotting (IB) using antibodies against phospho-ERK, phospho-p38 and phospho-JNK. To determine whether CCL2 treatments led to changes in the expression of genes involved in cartilage degeneration, human articular chondrocytes with or without recombinant CCL2 were incubated in serum free medium for mRNA collection; two different incubations were performed, a short treatment (6h) and a long treatment (18-24h). Quantitative RT-PCR analyses were performed to quantify the gene expression of mmp-1, mmp-3, mmp-13, comp and timp-1 using TaqMan method. Gene expression for the ccr2 receptor was also assessed. In some experiments, human articular chondrocytes were pre-incubated with the ERK inhibitor U0126 (10 mM) for 1 hour prior to CCL2 treatment, and then IB (for phospho-Erk) or qRT-PCR analyses (for mmp-13 and mmp-3) were performed. Results: CCL2 treatments of human chondrocytes led to activation of phospho-ERK and phospho-p38, but not phospho-JNK. When gene expression was assessed by RT-PCR, both short (6h) and long (18-24h) CCL2 treatments led to an upregulation of ccr2 expression compared to untreated controls, indicating a CCL2 positive feedback on its receptor. Both short and long CCL2 treatments also led to an upregulation in the expression of mmp's genes (mmp-1, mmp-3, and mmp-13), as well as an increased expression of the tissue inhibitor of metalloproteinases-1 (timp-1) and comp, which has been demonstrated to be a biomarker for cartilage breakdown. Inhibition of ERK signaling by U0126 abolished the CCL-2-induced upregulation of mmp-13, at both the short and long incubation times ( Figure 1). Interestingly, inhibition of ERK signaling did not significantly affect mmp-3 upregulation by CCL-2. Conclusions: Our data suggest that CCL2 stimulation of articular cartilage chondrocytes acts as positive feedback on its CCR2 receptor leading to cartilage degradation. The triggering of the CCL2/CCR2 axis leads to the activation of specific MAPK signaling pathways, such as ERK and p38 signaling. In particular, our results suggest that ERK signaling mediates the CCL-2-induced mmp-13 activation but may not be involved, or only partially involved, in the mmp-3 upregulation. Additional studies are currently in progress in our laboratory to determine whether inhibition of ERK and p38 is correlated to the expression of different genes involved in cartilage metabolism and degradation (such as mmp-1, timp-1, comp), fol...

Does moderate intensity impact exercise and non-impact exercise induce acute changes in collagen biochemical markers related to osteoarthritis? – An exploratory randomized cross-over trial

“…Generally, exercise is considered beneficial and cost-effective in improving pain and function in OA, although there has been widespread concern that some exercise modalities may accelerate degeneration, and thus low-impact exercise, like walking, is promoted over high-impact exercise, such as running 1,2 . Exercise may support joint tissue health by mechanical stimulation 3 and release of anti-inflammatory molecules 4 . On the contrary, OA leads to structural changes of joint tissue, which might increase the susceptibility to damage under loading and shear stress.…”

Evaluation of serum ARGS neoepitope as an osteoarthritis biomarker using a standardized model for exercise-induced cartilage extra cellular matrix turnover

“…Change of life-style is known to be beneficial [ 1 ] and in general physical activity is recommended to maintain mobility in Osteoarthritis (OA) [ 2 ]. Optimal loading of cartilage may promote anti-catabolic and anabolic effects in cartilage [ 3 , 4 ]. Yet, the acute impact of different exercise programs remains to be evaluated, although the joint load, and thus the effect, of running vs. cycling is considered different, and may present different clinical utility.…”