Immunoreactivity of human fetal membranes to peptidoglycan polysaccharide (PGPS): cytokine response

Objective: Group-B Streptococcus has been associated with preterm labor and other pregnancy related complications. This study was performed to evaluat e the effect of peptidoglycan polysaccharide (PGPS) derived from a beta hem olytic Streptococcal cell wall on amniochorion cytokine production and to c ompare PGPS effects with lipopolysaccharide (LPS), which is the Gram negati ve counterpart of PGPS. Study design: Amniochorionic membranes collected from women not in labor, a nd undergoing elective repeat C-section were placed in an organ explant sys tem. Membranes were stimulated separately with 50 ng/ml of small (100p), la rge (10s) fractions of PGPS or LPS respectively immediately after collectio n and after a stabilization period of 48 hrs. Media samples were collected at 3, 6, 9, 12 and 24 hrs for protein analysis after each stimulation. Medi a samples were analyzed by ELISA for IL-6 and IL-8. Results: Both forms of PGPS and LPS stimulated IL-6 and IL-8 production by human fetal membranes. Of note is that LPS stimulated IL-6 to a greater deg ree than IL-8, while PGPS stimulated IL-8 to a greater degree than IL-6. No statistical difference was seen in the levels of either one of these cytok ines for the larger or smaller fragments of PGPS. Time course studies docum ented a 3-hour lag phase when tissues are stimulated directly after collect ion which was absent when tissues are stimulated after a 48-hour stabilizat ion period. Conclusion: Both PGPS and LPS stimulate cytokine production differently fro m fetal membranes. This supports the theory that different bacteria may aff ect the host in contrasting ways which may lead to a distinct host response , ie FROM vs. PTL.