Figure 6.

Periostin augments collagen and proteoglycan degradation in OA cartilage explant cultures. Human OA cartilage explants from 4 independent patients were incubated with recombinant periostin (1 and 5 µg/ml) in duplicate wells of 24-well plates in serum-free medium. Medium was changed after 48 h and analyzed 72 h after addition of periostin. A) Type II collagen degradation (n = 4) assayed using the C1,2C-based ELISA. B) sGAG release (n = 4) measured by the DMB assay. IL-1 was used as a positive control for induction of matrix degradation. By post-ANOVA linear trend test between control and periostin treatment, the correlation was R² = 0.195; P = 0.0024 (C1,2C), and R² = 0.173; P = 0.0009 (sGAG), respectively. *P < 0.05; **P < 0.01.