Lipopolysaccharide-induced chorioamnionitis is confined to one amniotic compartment in twin pregnant sheep

Background: Chorioamnionitis is a major risk factor for preterm birth in multifetal pregnancies. However, there is little clinical data whether chorioamnionitis is restricted to one amniotic compartment in multifetal pregnancies. Objective: To explore whether chorioamnionitis is confined to the exposed compartment and does not cross to the unaffected fetus in twin pregnancy. Methods: In twin pregnant sheep, one of the twins was exposed to either 2 or 14 days of intra-amniotic lipopolysaccharide (LPS) while the co-twin was exposed to either 2 or 14 days of intra-amniotic saline (n = 3 for each exposure). Singletons were included in this study to compare the grade of inflammation with twins. All fetuses were delivered at 125 days of gestation (term = 150 days). Chorioamnionitis was confirmed by histological examination. Lung inflammation was assessed by cell count in bronchoalveolar lavage. Lung compliance was assessed at 40 cm H(2)O. Results were compared using analysis of variance (ANOVA) with a post-hoc Tukey analysis. Results: Inflammation in placenta, membranes and lung of LPS-exposed twins was significantly higher after 2 and 14 days of exposure when compared to the saline-exposed co-twins. Lung compliance in LPS-exposed twins was significantly increased after 14 days when compared to saline-exposed co-twins. Intrauterine LPS exposure increased lung compliance and inflammation in the membranes, placenta and lung to the same extent in twins as in singletons. Conclusion: In twin pregnant sheep, inflammation of the membranes, placenta and fetal lung was strictly limited to the exposed fetus in the amniotic compartment in which the LPS was injected.