Effect of PM2.5 Exposure On Gestational Hypertension and Fetal Size in Preeclampsia-Like Rats

Studies have reported that gestational PM2.5 exposure is associated with preeclampsia (PE) and fetal growth restriction (FGR). However, whether maternal exposure to PM2.5 causes adverse pregnancy outcomes is still largely unknown. Pregnant Sprague-Dawley rats were exposed to either filtered (FA) or PM2.5 air during the whole pregnant period. A PE-like rat model was established by intraperitoneal injection of L-NAME (300 mg/kg) from GD12 to until GD20. Systolic blood pressure (SBP), weight gain, pup weight and placental weight were measured. The percentages of rat Treg/Th17 cells and Th17-related cytokines were examined by flow cytometry. Gene expression profiles were analyzed by microarray, and the expression of differentially expressed genes were validated by qRT-PCR. The results showed that maternal PM2.5 exposure had no effect on SBP but was associated with LBW and a higher labyrinth/basal zone ratio. The percentages of splenic Th17 cells from the PM2.5 group in PE-like rats were higher than those from the FA or PM2.5 groups in healthy controls. A significantly decreased Treg/Th17 cell ratio was found in the PM2.5 group in PE-like rats. The mRNA expression of Foxp3 was downregulated, while the mRNA expression of RORα and RORγτ was upregulated after PM2.5 exposure. Furthermore, we observed that both the mRNA and protein expression of TNF-a, CCL2, CCL3 and CCR1 increased in the PM2.5 groups. Our study suggested that systemic inflammation may contribute to the development of FGR associated with PM2.5 exposure throughout pregnancy.