[Connective tissue degradation in human amniochorion after stimulation with choriodecidual lymphocytes infected with...

To identify whether soluble products from choriodecidual blood cells stimulated with group B streptococci (GBS) induce connective tissue degradation in human amniochorion.

Blood samples from choriodecidual compartment were collected by direct aspiration from placental cotyledons draining blood and represent local circulating cells. Samples were divided into two aliquots: one was stimulated with GBS (1 x 10(6) CFU/mL) and the other was kept free of bacteria as negative control. After overnight incubation, plasmas were separated. Chorioamnion explants were stimulated with 10% plasma for 12h at 37 degrees C in 5% CO2. MMP-9 proteolytic activity was measured in the supernatants by gelatin-zymography and IL-1beta and TNF-alpha were quantified by ELISA. Distribution of the collagenous fibrils in explants was examined by electron microscopy.

three independent experiments on duplicate were carried out and the statistical significance of experimental differences between groups was assessed with ANOVA test.

MMP-9, IL-1beta and TNF-alpha production was significantly higher in supernatants from explants co-cultured with choriodecidual plasma from blood previously infected with GBS, compared with control plasma. Accompanying extensive changes of connective tissue arrangement confirm induction of extracellular matrix degradation.

Choriodecidual plasma from blood stimulated with GBS is enriched with biochemical signals that enhance the MMP-9, IL-1beta and TNF-alpha production by amniochorion. These findings suggest that local circulating cells are capable to act in response to GBS choriodecidual infection through extracellular matrix degradation and the consequent rupture of membranes.