Regulation of Cultured Human Chorion Cell Chemokine Production by Group B Streptococci and Purified Bacterial Products

Abstract

PROBLEM: To determine if different strains of group B streptococci (GBS) and purified bacterial products regulate chemokine production by cultured human chorion cells. METHOD OF STUDY: Primary cultures of human chorion cells were established from placentae isolated from normal women at term gestation having repeat cesarean section. Five different strains of heat-killed GBS were incubated with confluent chorion cells at 10⁷ bacteria/ml for 16 hours at 37°C. In separate experiments, lipoteichoic acid and sialic acid at various concentrations were incubated with chorion cells for 16 hours at 37°C. Culture supernatants were collected and then assayed to determine concentrations of interleukin-8 (IL-8) and macrophage inflammatory protein-1α (MIP-1α) by ELISA. RESULTS: We found that GBS stimulated chorion cell production of MIP-1α in a strain-specific fashion. We also found that both lipoteichoic acid and sialic acid stimulated concentration-dependent increases in chorion cell IL-8 production. Chorion cells, however, did not increase MIP-1α production in response to either lipoteichoic acid or sialic acid. Two strains of GBS tested induced concentration-dependent increases in both IL-8 and MIP-1α, but both stimulated IL-8 production to a greater extent. Similarly, IL-1β also caused chorion cells to produce more IL-8 than MIP-1α. CONCLUSIONS: Our data are the first to show that GBS and purified bacterial products can stimulate chemokine production by fetal gestational tissues. We suggest that chorion cells may produce specific types of chemokines to attract different types of inflammatory cells and thus may participate in the pathophysiology of infection-mediated preterm labor by directing specific inflammatory responses.