Figure 1

MIF induces MMP-2 production by rheumatoid arthritis (RA) synovial fibroblasts. (a) RA synovial fibroblast MMP-2 production was measured in supernatants by ELISA after 6-hour (left) and 24-hour (right) incubation, with or without MIF (50 nM). MIF-stimulated RA synovial fibroblasts produced twice as much MMP-2 as controls. The mean concentration of MMP-2 ± standard error of the mean (SEM) is represented; *P < 0.05 (n = number of donors). (b) Gelatinase activity of RA synovial fibroblasts was measured using fluorescein-conjugated gelatin as substrate. Supernatants from 24-hour MIF-stimulated (50 nM) RA synovial fibroblasts had elevated gelatinase activity compared with nonstimulated fibroblasts. The mean fluorescence intensity ± SEM is represented; *P < 0.05 (n = number of donors). (c) MMP-2 production by RA synovial fibroblasts was measured by gelatin zymography. Molecular-weight marker and standard recombinant human MMP-2 and MMP-9 served as controls. Results are a single representative experiment of four independent experiments using RA synovial fibroblasts from four donors. MIF, macrophage migration inhibitory factor; MMP, matrix metalloproteinase; NS, nonstimulated; TNF-α, tumor necrosis factor-α.