S100A10 mediates activation of MMP-9. WT and S100A10−/− (KO) peritoneal macrophages (1 × 105 cells) were added to the upper chamber of Matrigel-coated chambers, which also contained Plg (0.5μM) and, where indicated, MMP-9 inhibitory antibody (20 μg/mL). The lower chamber contained MCP-1 (10 ng/mL) as chemoattractant (A). Cells were incubated at 37°C for 48 hours. Invading cells were quantified as described in “Matrigel invasion and cell migration.” Data are expressed as mean number of cells per field per 40 × field plus or minus SD of 3 independent experiments. Statistical analysis was performed by one-way analysis of variance (with Tukey multiple comparisons) compared with WT untreated macrophages: ***P < .001. WT and S100A10−/− macrophages were stimulated with Plg (0.5μM) and MCP-1 (10 ng/mL) for 24 hours in serum-free media. Cell lysates were prepared, electrophoresed, and immunoblotted for MMP-9 (B). WT and S100A10−/− macrophages were treated as in panel B, except that cell-conditioned media was collected. Conditioned media was subjected to zymography for MMP-9 (C; box indicates MMP-9 band; Pg, Plg; and Pm, plasmin), and quantification of MMP-9 was performed by densitometry and analyzed by Student t test (D).
