FIG. 3.

The amniochorion secretes MMP-9 in response to plasma from placental blood stimulated with GBS. (a) Representative zymography gel (0.5 μg of protein per lane). The bars represent the OD (optical densities) of pro-MMP-9 in supernatants of amniochorion explants cocultured with 10% plasma from nonstimulated placental blood (white) or plasma from placental blood stimulated with live (black) or heat-inactivated (gray) bacteria. (b) The bars represent the total MMP-9 (proenzyme and active enzyme) quantified by ELISA in the same supernatants. Coculture with plasma from placental blood stimulated with live or inactivated GBS significantly increased secretion of MMP-9 by the amniochorion explants (**, P ≤ 0.005; *, P ≤ 0.05). Active MMP-9 was detected only after treatment with plasma conditioned with live GBS in both experiments (arrow on the zymography gel in panel a). For both experiments, the final values were calculated by subtracting the original quantity secreted by untreated explants; thus, the bars reflect only the induced responses in the explants. Five independent experiments in duplicate are expressed as means and SD.