Transplacental Transfer of Interleukin-1 Receptor Agonist and Antagonist Following Maternal Immune Activation

Problem: Prenatal exposure to inflammation increases the incidence of neonatal brain injury. This raise the question whether maternally produced cytokines, especially interleukin (IL)-1 elevated in pathological pregnancies and known to alter fetal development, can cross the placental barrier and affect the fetus directly. Method of study: We addressed if IL-1 agonist/antagonist could cross the placenta. Results: Radiolabelled-IL-1 injected maternally reached the fetus in minimal amount. 3% of the amount detected within the placenta was transferred into the fetal liver and less than 1% recovered in the fetal brain 30 min after the injection Importantly, transfer of IL-1 was not affected by maternal exposure to LPS. Maternal administration of IL-1 receptor antagonist also reached the fetus in low concentration. Conclusions: This suggests that minimal amount of maternally produced IL-1 family members cross the placental barrier. Their negative effects are likely indirect, through their deleterious placental actions.