Inhalation of fine particulate matter during pregnancy increased IL-4 cytokine levels in the fetal portion of the placenta

•High IL-4 content was observed in the fetal portion of the placenta in rats exposed before and during pregnancy to air concentrated in fine particles.•A possible explanation for this finding is that IL-4 is increased in response to a previous inflammatory process induced by the polluted air since IL-4 has an anti-inflammatory effect.

This study aimed to verify the development of placental and systemic inflammation in rats exposed to fine particulate matter before or during pregnancy. Wistar rats were exposed to filtered air (control) or to a load of 600 μg/m3 of fine particles in the air. The gene expression of IL-1β, IL-4, IL-6, IL-10, INF-γ, TNF-α and Toll-like receptor 4 in the placenta was evaluated. The serum and placental concentrations of IL-1β, IL-4, IL-6, IL-10, INF-γ and TNF-α were measured. The total and differential blood leukocyte and blood platelet count was assessed. Compared to control animals, IL-4 content was elevated in the fetal portion of the placenta in rats exposed to air pollution before and during pregnancy. Increased IL-4 suggests that a placental inflammatory reaction may have occurred in response to exposure to fine particulate matter and that this cytokine was responsible, among possibly others factors, for resolution of the inflammatory reaction.