Fig. 5
Connection between IL-6 and PGE2 inflammation pathways and the mechanical stimulation. a Dynamic stretch was applied for 6 h to cultured chondrocytes (black bars), osteoblasts (white bars), and tenocytes (gray bars). Gene expression of Il-6 and Cox-2 were compared to non-stretched control cells. b IL-6 and PGE2 secretion was analyzed in the culture medium of chondrocytes and osteoblasts either in control (rest) or stretched conditions. c, d Piroxicam was added to chondrocytes to inhibit PGE2 synthesis. c The piroxicam-induced reduction in PGE2 content of the culture medium was validated in TNF-α-treated chondrocytes. d The effect of piroxicam on gene expression of Bmp-2 and -4 was analyzed in control or stretched conditions. e, f IL-6 blocking antibodies (Ab) were added to chondrocytes to inhibit IL-6 pathway. The effect of this treatment was compared to non-specific IgG1 antibodies (ctrl Ab). e Mmp-13 gene expression was analyzed in control or IL-6-treated chondrocytes and (f) Bmp-2 and -4 gene expression in control (rest) or stretched chondrocytes. *p < 0.05 in comparison to the control condition, p values are indicated for the differences between the other conditions, ns: not significant (p > 0.1)