Effect of PM2.5 exposure on gestational hypertension, fetal size in preeclampsia-like rats

PM2.5 associates with blood pressure: a Mendelian randomization analysis

The relationship between fine particulate matter (PM2.5) and blood pressure (BP) is a controversial issue. We conducted a two-sample Mendelian randomization (MR) analysis and identified 58 genome-wide significant single-nucleotide polymorphisms associated with PM2.5 as instrument variables. Inverse-variance weighted (IVW) was used as the primary analysis approach. MR-Egger, weighted median, simple model, and weighted model methods were selected for quality control. We found a significant negative causal association of higher genetically predicted PM2.5 levels with lower systolic BP (SBP), while no causal relationship was identified between PM2.5 and diastolic BP (DBP). For each 1 standard deviation increase in genetically predicted PM2.5 levels, the beta value (95% CI) of SBP was -0.14 (-0.25, -0.03) for IVW (p=0.02), and -0.13 (-0.22, -0.04) for weighted median (p=0.005). Increased PM2.5 concentrations can lead to decreased SBP levels. Our findings provided novel insights into the controversial topic on the causal relationship between PM2.5 and BP.

Gestational exposure to PM2.5 disrupts fetal development by suppressing placental trophoblast syncytialization via progranulin/mTOR signaling

Recent epidemiological and animal studies have indicated that ambient fine particulate matter (PM2.5) exposure during pregnancy is closely associated with intrauterine growth restriction (IUGR). However, the underlying mechanisms remain to be revealed. In this study, we found that gestational exposure to PM2.5 significantly decreased fetal weight and crown-rump length in mice, accompanied by insufficient placental trophoblast syncytialization and increased expression of progranulin (PGRN) in mice placenta. Administering PGRN neutralizing antibody to pregnant mice alleviated growth restriction and insufficient placental trophoblast syncytialization caused by PM2.5, accompanied with suppressed activation of the mTOR signaling pathway. Furthermore, in vitro experiments using human placental BeWo cells showed that 10 μg·mL-1 PM2.5 activated PGRN/mTOR signaling and suppressed forskolin-induced cell fusion, which was blocked by knockdown of PGRN. Taken together, our results demonstrated that PM2.5 exposure during pregnancy inhibited placental trophoblast syncytialization by activating PGRN/mTOR signaling, leading to abnormal placental development and IUGR. This study reveals a novel mechanism underlying the developmental toxicity of PM2.5 exposure during pregnancy.

DNA methylation profiles reveal sex-specific associations between gestational exposure to ambient air pollution and placenta cell-type composition in the PRISM cohort study

BACKGROUND

Gestational exposure to ambient air pollution has been associated with adverse health outcomes for mothers and newborns. The placenta is a central regulator of the in utero environment that orchestrates development and postnatal life via fetal programming. Ambient air pollution contaminants can reach the placenta and have been shown to alter bulk placental tissue DNA methylation patterns. Yet the effect of air pollution on placental cell-type composition has not been examined. We aimed to investigate whether the exposure to ambient air pollution during gestation is associated with placental cell types inferred from DNA methylation profiles.

METHODS

We leveraged data from 226 mother-infant pairs in the Programming of Intergenerational Stress Mechanisms (PRISM) longitudinal cohort in the Northeastern US. Daily concentrations of fine particulate matter (PM2.5) at 1 km spatial resolution were estimated from a spatiotemporal model developed with satellite data and linked to womens' addresses during pregnancy and infants' date of birth. The proportions of six cell types [syncytiotrophoblasts, trophoblasts, stromal, endothelial, Hofbauer and nucleated red blood cells (nRBCs)] were derived from placental tissue 450K DNA methylation array. We applied compositional regression to examine overall changes in placenta cell-type composition related to PM2.5 average by pregnancy trimester. We also investigated the association between PM2.5 and individual cell types using beta regression. All analyses were performed in the overall sample and stratified by infant sex adjusted for covariates.

RESULTS

In male infants, first trimester (T1) PM2.5 was associated with changes in placental cell composition (p = 0.03), driven by a decrease [per one PM2.5 interquartile range (IQR)] of 0.037 in the syncytiotrophoblasts proportion (95% confidence interval (CI) [- 0.066, - 0.012]), accompanied by an increase in trophoblasts of 0.033 (95% CI: [0.009, 0.064]). In females, second and third trimester PM2.5 were associated with overall changes in placental cell-type composition (T2: p = 0.040; T3: p = 0.049), with a decrease in the nRBC proportion. Individual cell-type analysis with beta regression showed similar results with an additional association found for third trimester PM2.5 and stromal cells in females (decrease of 0.054, p = 0.024).

CONCLUSION

Gestational exposure to air pollution was associated with placenta cell composition. Further research is needed to corroborate these findings and evaluate their role in PM2.5-related impact in the placenta and consequent fetal programming.

Association between ambient air pollution exposure in pregnant women with antiphospholipid syndrome in Nanjing, China

Antenatal exposure to air pollutants is thought to be associated with a variety of maternal blood markers as well as adverse birth outcomes. However, the dysgenic influence of air pollutants on the antiphospholipid syndrome (APS) in mothers and their pregnancy outcomes remains unclear. In the current study, 371 mother-infant pairs (189 healthy: 182 APS) from Nanjing Maternal and Child Health Hospital as well as air pollutants concentration from their living environment were used to investigate correlations between air pollution with maternal blood indicators and fetal birth weight in the groups of APS and healthy mothers. Generalized linear model was used to evaluate the contributions of air pollutant exposure during pregnancy to the blood indicators variation. The relationships between birth weight with specific air pollutant and blood index were analyzed using ridge regression. Results showed that APS fetal birth weight was significantly impacted by air pollutant exposure during pregnancy, in particular, the birth weight decreased significantly along with increasing fine particulate matter 2.5 (PM2.5) and fine particulate matter 10 (PM10) exposure concentrations throughout pregnancy. In contrast, birth weight increased significantly with sulfur dioxide (SO2) exposure. In addition, APS-related blood indicators comprised of platelet distribution width (PDW), total bilirubin (TBIL), mean platelet volume (MPV), platelet-larger cell ratio (P_LCR), homocysteine (HCY), alkaline phosphatase (ALP), direct bilirubin (DBIL), basophilic granulocyte (BAS), platelet thrombocytocrit (PCT), preprandial glucose levels (OGTT0), monocytes (MON), and monocytes ratio (MON_ratio) were also strongly related with prenatal exposure to PM2.5 and PM10, in which PDW levels showed most strongly negative impaction on fetal birth weight. Together, we showed that prenatal exposure to air pollutant (PM2.5 and PM10) may exacerbate the poor birth outcomes of low birth weight by impacting APS maternal blood indicators especially for PDW.

Ambient air pollution and maternal cardiovascular health in pregnancy

In this review, we summarise the current epidemiological and experimental evidence on the association of ambient (outdoor) air pollution exposure and maternal cardiovascular health during pregnancy. This topic is of utmost clinical and public health importance as pregnant women represent a potentially susceptible group due to the delicate balance of the feto-placental circulation, rapid fetal development and tremendous physiological adaptations to the maternal cardiorespiratory system during pregnancy.Several meta-analyses including up to 4 245 170 participants provide robust evidence that air pollutants, including particulate matter, nitrogen oxides and others, have adverse effects on the development of hypertensive disorders of pregnancy, gestational diabetes mellitus and cardiovascular events during labour. Potential underlying biological mechanisms include oxidative stress with subsequent endothelial dysfunction and vascular inflammation, β-cell dysfunction and epigenetic changes. Endothelial dysfunction can lead to hypertension by impairing vasodilatation and promoting vasoconstriction. Air pollution and the consequent oxidative stress can additionally accelerate β-cell dysfunction, which in turn triggers insulin resistance leading to gestational diabetes mellitus. Epigenetic changes in placental and mitochondrial DNA following air pollution exposures can lead to altered gene expression and contribute to placental dysfunction and induction of hypertensive disorders of pregnancy.The maternal and fetal consequences of such cardiovascular and cardiometabolic disease during pregnancy can be serious and long lasting, including preterm birth, increased risk of type 2 diabetes mellitus or cardiovascular disease later in life. Acceleration of efforts to reduce air pollution is therefore urgently needed to realise the full health benefits for pregnant mothers and their children.

Preeclampsia promotes autism in offspring via maternal inflammation and fetal NFκB signaling

Preeclampsia (PE) is a risk factor for autism spectrum disorder (ASD) in offspring. However, the exact mechanisms underlying the impact of PE on progeny ASD are not fully understood, which hinders the development of effective therapeutic approaches. This study shows the offspring born to a PE mouse model treated by Nω-nitro-L-arginine methyl ester (L-NAME) exhibit ASD-like phenotypes, including neurodevelopment deficiency and behavioral abnormalities. Transcriptomic analysis of the embryonic cortex and adult offspring hippocampus suggested the expression of ASD-related genes was dramatically changed. Furthermore, the level of inflammatory cytokines TNFα in maternal serum and nuclear factor kappa B (NFκB) signaling in the fetal cortex were elevated. Importantly, TNFα neutralization during pregnancy enabled to ameliorate ASD-like phenotypes and restore the NFκB activation level in the offspring exposed to PE. Furthermore, TNFα/NFκB signaling axis, but not L-NAME, caused deficits in neuroprogenitor cell proliferation and synaptic development. These experiments demonstrate that offspring exposed to PE phenocopies ASD signatures reported in humans and indicate therapeutic targeting of TNFα decreases the likelihood of bearing children with ASD phenotypes from PE mothers.

A systematic review on the association between exposure to air particulate matter during pregnancy and the development of hypertensive disorders of pregnancy and gestational diabetes mellitus

Particulate matter (PM) is considered an intrauterine toxin that can cross the blood-placental barrier and circulate in fetal blood, affecting fetal development, and implicating placental and intrauterine inflammation, and oxidative damage. However, the relationship between PM exposure and adverse pregnancy outcomes is still unclear and our aim was to systematically review toxicological evidence on the link between PM exposure during pregnancy and the development of gestational diabetes mellitus or hypertensive disorders of pregnancy, including gestational hypertension and pre-eclampsia. PubMed and Science Direct were searched until January 2022. Of the 204 studies identified, 168 were excluded. The remaining articles were assessed in full-text, and after evaluation, 27 were included in the review. Most of the studies showed an association between PM exposure and gestational hypertension, systolic and diastolic blood pressure, pre-eclampsia, and gestational diabetes mellitus. These results should be interpreted with caution due to the heterogeneity of baseline concentrations, which ranged from 3.3 μg/m3 to 85.9 μg/m3 and from 21.8 μg/m3 to 92.2 μg/m3, respectively for PM2.5 and PM10. Moreover, critical exposure periods were not consistent among studies, with five out of ten observational studies reporting the second trimester as the critical period for hypertensive disorders of pregnancy, and ten out of twelve observational studies reporting the first or second trimester as the critical period for gestational diabetes mellitus. Overall, the findings support an association between PM exposure during pregnancy and adverse pregnancy outcomes, highlighting the need for further research to identify the critical exposure periods and underlying mechanisms.