Figure 3

Gelatin zymography of culture medium conditioned by fibroblast-like synoviocytes (FLS) and monocytes/macrophages. Cells were cultured in serum-free media for 24 hours, and the conditioned media were collected and analyzed for matrix metalloproteinase (MMP) activity by gelatin zymography. (a) Secretion and activation of MMPs in rheumatoid arthritis (RA) FLS, monocytes/macrophages, RA FLS co-cultured with monocytes/macrophages, and in co-cultured cells treated by AP-9 or SSP, and ethylenediamine tetraacetic acid or phenanthroline. Top two bands, MMP-9 gelatinase; lower two bands, MMP-2 gelatinase. (b) The value of proMMP-2 and MMP-2 activity of monocytes from peripheral blood of healthy humans (Mo-PB) was lower than monocytes/macrophages from synovial fluid of RA patients (Mo-SF) (n = 10, P < 0.05). (c) The value of proMMP-9, MMP-9, proMMP-2 and MMP-2 activity of RA FLS co-cultured with Mo-PB was higher than that of co-cultured cells treated by AP-9 (n = 6, P < 0.05), while no inhibitory effects were found in irrelevant peptide SSP (n = 6, P > 0.05). (d) The value of proMMP-9, MMP-9, proMMP-2 and MMP-2 activity of RA FLS co-cultured with Mo-SF was higher than that of co-cultured cells treated by AP-9 (n = 6, P < 0.05), while no inhibitory effects were found in irrelevant peptide SSP (n = 6, P > 0.05). Values are the means ± standard error (n = 6–10). *P < 0.05 (experimental groups versus control groups).