Modulation of lipopolysaccharide-induced chorioamnionitis by Ureaplasma parvum in sheep.

Objective: Ureaplasma colonization in the setting of polymicrobial flora is common in women with chorioamnionitis, and is a risk factor for preterm delivery and neonatal morbidity. We hypothesized that Ureaplasma colonization of amniotic fluid would modulate chorioamnionitis induced by Escherichia coli lipopolysaccharide (LPS). Study Design: Sheep received intraamniotic (IA) injections of media (control) or live Ureaplasma either 7 or 70 days before delivery. Another group received IA LPS 2 days before delivery. To test for interactions, U parvum–exposed animals were challenged with IA LPS, and delivered 2 days later. All animals were delivered preterm at 125 ± 1 day of gestation. Results: Both IA Ureaplasma and LPS induced leukocyte infiltration of chorioamnion. LPS greatly increased the expression of proinflammatory cytokines and myeloperoxidase in leukocytes, while Ureaplasma alone caused modest responses. Interestingly, 7-day but not 70-day Ureaplasma exposure significantly down-regulated LPS-induced proinflammatory cytokines and myeloperoxidase expression in the chorioamnion. Conclusion: Acute (7-day) U parvum exposure can suppress LPS-induced chorioamnionitis. [ABSTRACT FROM AUTHOR]