Placental-fetal distribution of carbon particles in a pregnant rabbit model after repeated exposure to diluted diesel engine exhaust

Prenatal PM2.5 exposure affects embryonic hematopoietic development through SOX2-regulated gene expression

Fine particulate matter (PM2.5) is one of the most concerning air pollutants, with emerging evidence indicating that it can negatively impact embryonic development and lead to adverse birth outcomes. Hematopoiesis is a critical process essential for the survival and normal development of the embryo, consisting of three temporally overlapping stages and involving multiple hematopoietic loci, including the yolk sac and fetal liver. Therefore, we hypothesized that abnormal embryonic hematopoietic development can significantly influence developmental outcomes. In this study, we established a prenatal PM2.5 exposure model and observed decreased embryo weights and elevated platelet counts at embryonic day 18.5 (E18.5). Additionally, we employed flow cytometry and colony-forming unit assays, which revealed a significant decrease in the proliferative differentiation potential of erythro-myeloid progenitors in the E10.5 yolk sac, as well as a reduction in both the number and function of hematopoietic stem progenitor cells in the E14.5 fetal liver. Through bioinformatic analysis, we identified that these alterations are associated with several typical biological processes and genes regarding cell proliferation, cell differentiation, response to hypoxia, and regulation of hematopoiesis. Importantly, via quantitative real-time PCR, chromatin immunoprecipitation, and immunofluorescence, we further elucidated that prenatal exposure to PM2.5 affects embryonic hematopoiesis by regulating the expression of SOX2, an important transcription factor involved in embryonic development, along with its related genes. Collectively, these findings provide experimental evidence supporting the necessity for controlling regional PM2.5 exposure to promote child well-being in polluted areas.

Impact on murine neurodevelopment of early-life exposure to airborne ultrafine carbon nanoparticles

The effects of ultrafine particle (UFP) inhalation on neurodevelopment, especially during critical windows of early life, remain largely unexplored. The specific time windows during which exposure to UFP might be the most detrimental remain poorly understood. Here, we studied early-life exposure to clean ultrafine carbonaceous particles (UFPC) and neurodevelopment and central nervous system function in offspring.Pregnant wild-type C57BL/6J mice were either sham-exposed (HEPA-filtered air) or exposed to clean ultrafine carbonaceous particles at a concentration of 438 ± 72 μg/m³ (mean ± SD) and a count median diameter of 49 ± 2 nm (CMD ± GSD) via whole-body exposure for four hours per day. For prenatal exposure, mice were exposed for two consecutive days in two exposure periods, while the postnatal exposure was conducted for four consecutive days in two exposure periods. The mice were divided into four groups: (i) sham, (ii) only prenatal exposure, (iii) only postnatal exposure, and (iv) both prenatal and postnatal exposure. Neurodevelopmental behaviour was assessed throughout the life of the offspring using a functional observation battery.Early-life UFPC-exposed offspring exhibited altered anxiety-related behaviour in the open field test, with exclusively postnatally exposed offspring (567 ± 120 s) spending significantly more time within the border zone of the arena compared to the sham group (402 ± 73 s), corresponding to an increase of approximately 41% (p < 0.05). The behavioural alterations remained unaffected by olfactory function or maternal behaviour. Mice with both prenatal and postnatal exposure did not show this effect. No discernible impact on developmental behavioural reflexes was evident.Early life exposure to UFPC, particularly during the early postnatal period, may lead to developmental neurotoxicity, potentially resulting in complications for the central nervous system later in life. The current data will support future studies investigating the possible effects and characteristics of nanoparticle-based toxicity.

Maternal diesel particle exposure alters gut microbiota and induces lung injury in rat offspring

Maternal air pollutant exposure inhibits fetal lung development. Diesel exhaust particles (DEP) are one of the most substantial contributors to particulate matter pollution. The effects of maternal DEP exposure on gut microbiota in mothers and offspring and fetal lung development remain unclear. In this study, time-dated pregnant Sprague Dawley rats received intranasal administration of 100 μL phosphate-buffered saline (PBS) or DEP (250 μg) in 100 μL PBS from gestational days 16-21. The dams were permitted to deliver vaginally at term. On postnatal days 0 and 7, gut microbiota was sampled from the lower gastrointestinal tract. The right lung and terminal ileum were harvested for histological, cytokine, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) analyses. On postnatal day 0, the dams exposed to DEP and rat offspring with maternal DEP exposure exhibited macrophages that phagocytized diesel particles and increased numbers of macrophages in the alveolar parenchyma. On postnatal days 0 and 7, the offspring of DEP-exposed dams exhibited significantly lower intestinal tight junction protein expression, higher lung 8-OHdG and cytokine levels, and substantial lung injury compared with the offspring of the control dams. No significant differences were observed in the microbiota composition and diversity between the control and DEP-exposed dams. Maternal DEP exposure altered the gut microbiota composition and diversity on postnatal days 0 and 7, with more significant effects observed in the offspring on postnatal day 7. Regarding the mechanism, lung injury in offspring may have been linked to altered gut microbiota communities and dysregulated metabolic pathways caused by maternal DEP exposure.

Relation of prenatal and postnatal PM2.5 exposure with cognitive and motor function among preschool-aged children

The literature informing susceptible periods of exposure on children's neurodevelopment is limited. We evaluated the impacts of pre- and postnatal fine particulate matter (PM2.5) exposure on children's cognitive and motor function among 1303 mother-child pairs in the Spanish INMA (Environment and Childhood) Study. Random forest models with temporal back extrapolation were used to estimate daily residential PM2.5 exposures that we averaged across 1-week lags during the prenatal period and 4-week lags during the postnatal period. The McCarthy Scales of Children's Abilities (MSCA) were administered around 5 years to assess general cognitive index (GCI) and several subscales (verbal, perceptual-performance, memory, fine motor, gross motor). We applied distributed lag nonlinear models within the Bayesian hierarchical framework to explore periods of susceptibility to PM2.5 on each MSCA outcome. Effect estimates were calculated per 5 μg/m3 increase in PM2.5 and aggregated across adjacent statistically significant lags using cumulative β (βcum) and 95% Credible Intervals (95%CrI). We evaluated interactions between PM2.5 with fetal growth and child sex. We did not observe associations of PM2.5 exposure with lower GCI scores. We found a period of susceptibility to PM2.5 on fine motor scores in gestational weeks 1-9 (βcum = -2.55, 95%CrI = -3.53,-1.56) and on gross motor scores in weeks 7-17 (βcum = -2.27,95%CrI = -3.43,-1.11) though the individual lags for the latter were only borderline statistically significant. Exposure in gestational week 17 was weakly associated with verbal scores (βcum = -0.17, 95%CrI = -0.26,-0.09). In the postnatal period (from age 0.5-1.2 years), we observed a window of susceptibility to PM2.5 on lower perceptual-performance (β = -2.42, 95%CrI = -3.37,-1.46). Unexpected protective associations were observed for several outcomes with exposures in the later postnatal period. We observed no evidence of differences in susceptible periods by fetal growth or child sex. Preschool-aged children's motor function may be particularly susceptible to PM2.5 exposures experienced in utero whereas the first year of life was identified as a period of susceptibility to PM2.5 for children's perceptual-performance.

Nanoparticles at the maternal-fetal interface

The increasing production of intentional and unintentional nanoparticles (NPs) has led to their accumulation in the environment as air and ground pollution. The heterogeneity of these particles primarily relies on the NP physicochemical properties (i.e., chemical composition, size, shape, surface chemistry, etc.). Pregnancy represents a vulnerable life stage for both the woman and the developing fetus. The ubiquitous nature of these NPs creates a concern for developmental fetal exposures. At the maternal-fetal interface lies the placenta, a temporary endocrine organ that facilitates nutrient and waste exchange as well as communication between maternal and fetal tissues. Recent evidence in human and animal models identifies that gestational exposure to NPs results in placental translocation leading to local effects and endocrine disruption. Currently, the mechanisms underlying placental translocation and cellular uptake of NPs in the placenta are poorly understood. The purpose of this review is to assess the current understanding of the physiochemical factors influencing NP translocation, cellular uptake, and endocrine disruption at the maternal-fetal interface within the available literature.