Stimulation of RASFCs and chondrocytes with IL-17A alone and combined with TNF-α and OSM causing significant matrix turnover. Primary synovial fibroblasts (RASFCs; white bars) and chondrocytes (black bars) were cultured in the presence of IL-17A (50 ng/ml) alone and in combination with TNF-α (10 ng/ml) or oncostatin M (OSM; 10 ng/ml) for 15 days and 24 hours respectively. (a to d) Culture supernatants were analysed for the expression of matrix metalloproteinase (MMP)-1 and MMP-13 by ELISA. Values are the mean and standard error results from nine experiments (RASFCs) and five experiments (chondrocytes). * P < 0.05 versus baseline. (e) MMP-2 activity was examined by gelatin zymography in the culture supernatants.