Figure 6

Effect of HMGB1 and IL-1β on MMP mRNA levels in osteoarthritic synoviocytes and MMP activity released into the medium. (a) Matrix metalloproteinase (MMP)-1, MMP-3 and MMP-13 mRNA levels and (b) MMP activity. Cells were stimulated with IL-1b (10 ng/ml) for 24 hours in the presence or absence of high mobility group box 1 (HMGB1) at 15 and 25 ng/m. mRNA was determined by real-time PCR and MMP activity was measured in supernatants by a fluorometric procedure, as indicated in Materials and Methods. Data are expressed as mean ± standard error of the mean. Duplicate samples from four patients were used. ++P < 0.01 with respect to nonstimulated cells. *P < 0.05, **P < 0.01 with respect to IL-1β.