The effects of particulate ambient air pollution on the murine umbilical cord and its vessels: A quantitative morphological and immunohistochemical study

Ambient air pollution and adverse birth outcomes: A review of underlying mechanisms

Epidemiological data provide varying degrees of evidence for associations between prenatal exposure to ambient air pollutants and adverse birth outcomes (suboptimal measures of fetal growth, preterm birth and stillbirth). To assess further certainty of effects, this review examines the experimental literature base to identify mechanisms by which air pollution (particulate matter, nitrogen dioxide and ozone) could cause adverse effects on the developing fetus. It likely that this environmental insult impacts multiple biological pathways important for sustaining a healthy pregnancy, depending upon the composition of the pollutant mixture and the exposure window owing to changes in physiologic maturity of the placenta, its circulations and the fetus as pregnancy ensues. The current body of evidence indicates that the placenta is a target tissue, impacted by a variety of critical processes including nitrosative/oxidative stress, inflammation, endocrine disruption, epigenetic changes, as well as vascular dysregulation of the maternal-fetal unit. All of the above can disturb placental function and, as a consequence, could contribute to compromised fetal growth as well increasing the risk of stillbirth. Furthermore, given that there is often an increased inflammatory response associated with preterm labour, inflammation is a plausible mechanism mediating the effects of air pollution on premature delivery. In the light of increased urbanisation and an ever-changing climate, both of which increase ambient air pollution and negatively affect vulnerable populations such as pregnant individuals, it is hoped that the collective evidence may contribute to decisions taken to strengthen air quality policies, reductions in exposure to air pollution and subsequent improvements in the health of those not yet born.

The effects of prenatal PM2.5 oxidative potential exposure on feto-placental vascular resistance and fetal weight: A repeated-measures study

BACKGROUND

Feto-placental hemodynamic deterioration is a critical contributing factor to fetal growth restriction. Whether PM2.5 oxidative potential (OP) affects feto-placental hemodynamics and what impact is on estimated fetal weight (EFW) have not been fully elucidated. We sought to evaluate the association of PM2.5 OP with EFW and to explore whether feto-placental vascular impedance hemodynamic change is a possible mediator in this association.

METHODS

A repeated-measures study was conducted involving sixty pregnant women with at least 26 weeks of follow-up during pregnancy in Guangzhou, China, from September 2017 to October 2018. Daily filter-based PM2.5 samples were prospectively collected from ground monitors, and estimates of OP for PM2.5 and its metallic (OPv-metal) and non-metallic constituents (OPv-nonmental) were determined by dithiothreitol assay. Ultrasound data of fetal growth and umbilical arterial resistance, including estimated fetal weight (EFW), pulsatility index, resistance index, and systolic-to-diastolic ratio, were also obtained during gestation. Generalized estimating equations and polynomial distribution lag models were applied to analyze the associations of maternal exposure to PM2.5 OP with EFW and umbilical artery indices. Causal mediation analysis was used to evaluate the mediating role of umbilical arterial resistance.

RESULTS

Prenatal exposure to ambient PM2.5 OP was significantly inversely associated with EFW. The magnitudes of effects of OPv-nonmetal on EFW were larger than those of OPv-metal. Significant mediation for the relationship between PM2.5-related OP and EFW by increased impedance in the umbilical artery was observed, with the estimated percent mediated ranging from 31% to 61%. The estimated percent mediated for OPv-nonmetal was higher than those for OPv-metal.

CONCLUSIONS

Findings suggest that increased impedance in the umbilical artery may be one of the potential mediators of the relationship between PM2.5 oxidative potential exposure and low fetal weight.

Association between maternal short-term exposure to ambient air pollution and the risk of fetal distress: A matched case-control study

BACKGROUND

Ambient air pollution has been linked to gestational complications. However, the evidence on the relationship between air pollution and fetal distress is limited.

OBJECTIVES

To investigate the relationship between maternal short-term air pollution exposure and fetal distress, and to identify a potential susceptible population.

METHODS

This matched case-control study, involving 313 pregnancy women with fetal distress was conducted in Xi'an, the largest city in Northwest China from 2013 to 2016. Each woman with fetal distress was randomly matched with four women without fetal distress of the same age, same gestational week, and registration in the same period (n = 1252). Inverse distance-weighted (IDW) interpolation was applied to estimate maternal air pollution exposure based on the residential addresses. We employed conditional logistic regression model to evaluate the relationship between air pollutants and fetal distress. Distributed lag nonlinear model (DLNM) was performed to examine the exposure-response relationship between air pollutants and fetal distress.

RESULTS

Maternal short-term exposure to PM₁₀, PM_2.5-10 (PMc), SO₂, NO₂, and CO was associated with increased risk of fetal distress. Each 10 μg/m³ increment in PM₁₀, PMc, SO₂ at lag 014, and NO₂ at lag 010, the odds ratio (ORs) of fetal distress were 1.027 (95 % confidence interval (CI): 1.004, 1.050), 1.058 (95 % CI: 1.014, 1.105), 1.140 (95 % CI: 1.029, 1.264), and 1.158 (95 % CI: 1.046, 1.283), respectively. Similarly, with a 0.1 mg/m³ increment in CO at lag 014, the OR of fetal distress was 1.029 (95 % CI: 1.002, 1.058). Stratified analyses showed that the estimate associations of PM₁₀, PM_2.5 and CO appeared to be stronger, although not statistically significantly, among women with gestational complications.

CONCLUSION

Maternal short-term exposure to ambient air pollution may increase the risk of fetal distress. Understanding the detrimental role of air pollution in fetal distress can help us better develop preventative methods in reducing its' impact on maternal and fetal health.

The Potential Role of PPARs in the Fetal Origins of Adult Disease

The fetal origins of adult disease (FOAD) hypothesis holds that events during early development have a profound impact on one’s risk for the development of future adult disease. Studies from humans and animals have demonstrated that many diseases can begin in childhood and are caused by a variety of early life traumas, including maternal malnutrition, maternal disease conditions, lifestyle changes, exposure to toxins/chemicals, improper medication during pregnancy, and so on. Recently, the roles of Peroxisome proliferator-activated receptors (PPARs) in FOAD have been increasingly appreciated due to their wide variety of biological actions. PPARs are members of the nuclear hormone receptor subfamily, consisting of three distinct subtypes: PPARα, β/δ, and γ, highly expressed in the reproductive tissues. By controlling the maturation of the oocyte, ovulation, implantation of the embryo, development of the placenta, and male fertility, the PPARs play a crucial role in the transition from embryo to fetus in developing mammals. Exposure to adverse events in early life exerts a profound influence on the methylation pattern of PPARs in offspring organs, which can affect development and health throughout the life course, and even across generations. In this review, we summarize the latest research on PPARs in the area of FOAD, highlight the important role of PPARs in FOAD, and provide a potential strategy for early prevention of FOAD.

NRF2-Dependent Placental Effects Vary by Sex and Dose following Gestational Exposure to Ultrafine Particles

Exposure to ultrafine particles (UFPs, PM0.1) during pregnancy triggers placental oxidative stress and inflammation, similar to fine PM (PM2.5). The Nrf2 gene encodes a redox-sensitive transcription factor that is a major regulator of antioxidant and anti-inflammatory responses. Disruption of NRF2 is known to substantially enhance PM2.5-driven oxidant and inflammatory responses; however, specific responses to UFP exposure, especially during critical windows of susceptibility such as pregnancy, are not fully characterized; To investigate the role of NRF2 in regulating maternal antioxidant defenses and placental responses to UFP exposure, wildtype (WT) and Nrf2-/- pregnant mice were exposed to either low dose (LD, 100 µg/m3) or high dose (HD, 500 µg/m3) UFP mixture or filtered air (FA, control) throughout gestation; Nrf2-/- HD-exposed female offspring exhibited significantly reduced fetal and placental weights. Placental morphology changes appeared most pronounced in Nrf2-/- LD-exposed offspring of both sexes. Glutathione (GSH) redox analysis revealed significant increases in the GSH/GSSG ratio (reduced/oxidized) in WT female placental tissue exposed to HD in comparison with Nrf2-/- HD-exposed mice. The expression of inflammatory cytokine genes (Il1β, Tnfα) was significantly increased in Nrf2-/- placentas from male and female offspring across all exposure groups. Genes related to bile acid metabolism and transport were differentially altered in Nrf2-/- mice across sex and exposure groups. Notably, the group with the most marked phenotypic effects (Nrf2-/- HD-exposed females) corresponded to significantly higher placental Apoa1 and Apob expression suggesting a link between placental lipid transport and NRF2 in response to high dose UFP exposure; Disruption of NRF2 exacerbates adverse developmental outcomes in response to high dose UFP exposure in female offspring. Morphological effects in placenta from male and female offspring exposed to low dose UFPs also signify the importance of NRF2 in maternal-fetal response to UFPs.

Vitamin D3 protects intrauterine growth restriction induced by cooking oil fume derived fine particulate matters

BACKGROUND

Cooking oil fume (COF) is an important source of indoor air pollution which severely affects human health, and sufficient vitamin D₃ (VitD₃) is necessary for maternal and child health. However, the effects of cooking oil fume-derived PM_2.5 (COF-PM_2.5) on birth outcomes and whether VitD₃ could protect from adverse effects caused by COFs-PM_2.5 are still unclear.

METHODS

Twenty-four pregnant rats were divided into 4 groups and treated with various treatments: normal feeding, COFs-PM_2.5 intratracheal instillation, VitD₃ intragastric administration, and COFs-PM_2.5 and VitD₃ co-treatment, respectively. The fetal rats were obtained in pregnant 21 days and the development of them was recorded. Morphological changes in umbilical cord were measured with HE staining, and the oxidative stress and inflammatory levels were also investigated. Western blotting and RT-PCR was used to detect the expression of angiogenesis related factors.

RESULTS

We successfully established an intrauterine growth restriction model in rats induced by COFs-PM_2.5 where fetus weight significantly decreased after COFs-PM_2.5 exposure. As for the umbilical cord vasculature, the wall thickened and the lumen narrowed down, and the contractility of the umbilical cord vasculature enhanced after COFs-PM_2.5 exposure. COFs-PM_2.5 exposure also increased the oxidative stress and inflammation level and activated the HIF-1α/eNOS/NO and VEGF/VEGFR2/eNOS signaling pathway. Interestingly, VitD₃ intervention significantly increased the fetus weight and attenuated the injury of umbilical cord vascular, and partly or completely reversed the changes in the ROS/eNOS/ET-1 axis caused by COF-PM_2.5.

CONCLUSIONS

The findings of this study suggested that COF-PM_2.5 exposure could contribute to intrauterine growth restriction through disturbing the ROS/eNOS/ET-1 axis, while VitD₃ supplementation could be an effective prophylactic measurement.

Association Between Ambient Air Pollutants Exposure and Preterm Birth in Women Who Underwent in vitro Fertilization: A Retrospective Cohort Study From Hangzhou, China

Objectives: Exposure to air pollutants has been linked to preterm birth (PTB) after natural conception. However, few studies have explored the effects of air pollution on PTB in patients who underwent in vitro fertilization (IVF). We aimed to investigate the association between ambient air pollutants exposure and PTB risk in IVF patients.

Methods: This retrospective cohort study included 2,195 infertile women who underwent IVF treatment from January 2017 and September 2020 in Hangzhou Women's Hospital. Totally 1,005 subjects who underwent a first fresh embryo(s) transfer cycle were analyzed in this study. Residential exposure to ambient six air pollutants (PM_2.5, PM₁₀, SO₂, NO₂, CO, O₃) during various periods of the IVF timeline were estimated by satellite remote-sensing and ground measurement. Cox proportional hazards models for discrete time were used to explore the association between pollutants exposure and incident PTB, with adjustment for confounders. Stratified analyses were employed to explore the effect modifiers.

Results: The clinical pregnancy and PTB rates were 61.2 and 9.3%, respectively. We found that PM_2.5 exposure was significantly associated with an increased risk of PTB during 85 days before oocyte retrieval [period A, adjusted hazard ratio, HR=1.09, 95%CI: 1.02–1.21], gonadotropin start to oocyte retrieval [period B, 1.07 (1.01–1.19)], first trimester of pregnancy [period F, 1.06 (1.01–1.14)], and the entire IVF pregnancy [period I, 1.07 (1.01–1.14)], respectively. An interquartile range increment in PM₁₀ during periods A and B was significantly associated with PTB at 1.15 (1.04–1.36), 1.12 (1.03–1.28), and 1.14 (1.01–1.32) for NO₂ during period A. The stratified analysis showed that the associations were stronger for women aged <35 years and those who underwent two embryos transferred.

Conclusions: Our study suggests ambient PM_2.5, PM₁₀, and NO₂ exposure were significantly associated with elevated PTB risk in IVF patients, especially at early stages of IVF cycle and during pregnancy.

Acute ambient air pollution exposure and placental Doppler results in the NICHD fetal growth studies - Singleton cohort

BACKGROUND

Increased placental vascular resistance is a proposed mechanism by which air pollution exposure during pregnancy lowers birth weight and increases pregnancy-induced hypertensive disorders.

OBJECTIVE

To examine the impact of acute air pollution exposure during pregnancy on uterine and umbilical artery Doppler indicators of placental vascular resistance.

METHODS

After a first ultrasound to confirm gestational age, 2562 pregnant women recruited in 12 clinics throughout the United States underwent up to five standardized ultrasounds with Doppler measurements. Exposures to 11 air pollutants were estimated for the hour of ultrasound and each of the 2 h prior to ultrasound at the clinics using the National Air Quality Forecast Capability reanalysis products. We used mixed logistic regression to study the longitudinal odds ratio (OR) of any, uni- or bi-lateral systolic and diastolic uterine artery notching compared to no notching and the longitudinal OR of abnormal end diastolic flow of the umbilical artery compared to forward flow. Uterine and umbilical artery resistance indexes were studied using linear mixed models.

RESULTS

Each inter-quartile range (IQR) increase of particulate matter < 2.5 μm, nitrate, ammonium, primary organic matter (POM) and nitrogen dioxide during the hour of ultrasound was associated with a decreased risk of unilateral systolic notch and with increased resistance index of the left uterine artery. For the umbilical artery, each IQR increase in ozone was associated with decreased resistance index (b: -0.26, 95 % CI: -0.52, -0.01) and with a decreased risk of abnormal end diastolic flow (OR: 0.36, 95 % CI: 0.14, 0.94); while each IQR increase of elemental carbon and POM was associated with increased risk of abnormal end diastolic flow (OR: 1.47, 95 % CI: 1.02, 2.13 and OR: 1.67, 95 % CI: 1.17, 2.39, respectively).

DISCUSSION

Our results suggest acute air pollution exposure may influence placental vascular resistance.

Ambient and household PM2.5 pollution and adverse perinatal outcomes: A meta-regression and analysis of attributable global burden for 204 countries and territories

BACKGROUND

Particulate matter <2.5 micrometer (PM2.5) is associated with adverse perinatal outcomes, but the impact on disease burden mediated by this pathway has not previously been included in the Global Burden of Disease (GBD), Mortality, Injuries, and Risk Factors studies. We estimated the global burden of low birth weight (LBW) and preterm birth (PTB) and impacts on reduced birth weight and gestational age (GA), attributable to ambient and household PM2.5 pollution in 2019.

METHODS AND FINDINGS

We searched PubMed, Embase, and Web of Science for peer-reviewed articles in English. Study quality was assessed using 2 tools: (1) Agency for Healthcare Research and Quality checklist; and (2) National Institute of Environmental Health Sciences (NIEHS) risk of bias questions. We conducted a meta-regression (MR) to quantify the risk of PM2.5 on birth weight and GA. The MR, based on a systematic review (SR) of articles published through April 4, 2021, and resulting uncertainty intervals (UIs) accounted for unexplained between-study heterogeneity. Separate nonlinear relationships relating exposure to risk were generated for each outcome and applied in the burden estimation. The MR included 44, 40, and 40 birth weight, LBW, and PTB studies, respectively. Majority of the studies were of retrospective cohort design and primarily from North America, Europe, and Australia. A few recent studies were from China, India, sub-Saharan Africa, and South America. Pooled estimates indicated 22 grams (95% UI: 12, 32) lower birth weight, 11% greater risk of LBW (1.11, 95% UI: 1.07, 1.16), and 12% greater risk of PTB (1.12, 95% UI: 1.06, 1.19), per 10 μg/m3 increment in ambient PM2.5. We estimated a global population-weighted mean lowering of 89 grams (95% UI: 88, 89) of birth weight and 3.4 weeks (95% UI: 3.4, 3.4) of GA in 2019, attributable to total PM2.5. Globally, an estimated 15.6% (95% UI: 15.6, 15.7) of all LBW and 35.7% (95% UI: 35.6, 35.9) of all PTB infants were attributable to total PM2.5, equivalent to 2,761,720 (95% UI: 2,746,713 to 2,776,722) and 5,870,103 (95% UI: 5,848,046 to 5,892,166) infants in 2019, respectively. About one-third of the total PM2.5 burden for LBW and PTB could be attributable to ambient exposure, with household air pollution (HAP) dominating in low-income countries. The findings should be viewed in light of some limitations such as heterogeneity between studies including size, exposure levels, exposure assessment method, and adjustment for confounding. Furthermore, studies did not separate the direct effect of PM2.5 on birth weight from that mediated through GA. As a consequence, the pooled risk estimates in the MR and likewise the global burden may have been underestimated.

CONCLUSIONS

Ambient and household PM2.5 were associated with reduced birth weight and GA, which are, in turn, associated with neonatal and infant mortality, particularly in low- and middle-income countries.

Air pollution and children's health-a review of adverse effects associated with prenatal exposure from fine to ultrafine particulate matter

BACKGROUND

Particulate matter (PM), a major component of ambient air pollution, accounts for a substantial burden of diseases and fatality worldwide. Maternal exposure to PM during pregnancy is particularly harmful to children's health since this is a phase of rapid human growth and development.

METHOD

In this review, we synthesize the scientific evidence on adverse health outcomes in children following prenatal exposure to the smallest toxic components, fine (PM_2.5) and ultrafine (PM_0.1) PM. We highlight the established and emerging findings from epidemiologic studies and experimental models.

RESULTS

Maternal exposure to fine and ultrafine PM directly and indirectly yields numerous adverse birth outcomes and impacts on children's respiratory systems, immune status, brain development, and cardiometabolic health. The biological mechanisms underlying adverse effects include direct placental translocation of ultrafine particles, placental and systemic maternal oxidative stress and inflammation elicited by both fine and ultrafine PM, epigenetic changes, and potential endocrine effects that influence long-term health.

CONCLUSION

Policies to reduce maternal exposure and health consequences in children should be a high priority. PM_2.5 levels are regulated, yet it is recognized that minority and low socioeconomic status groups experience disproportionate exposures. Moreover, PM_0.1 levels are not routinely measured or currently regulated. Consequently, preventive strategies that inform neighborhood/regional planning and clinical/nutritional recommendations are needed to mitigate maternal exposure and ultimately protect children's health.

Air pollution and cardiovascular disease: car sick

The cardiovascular effects of inhaled particle matter (PM) are responsible for a substantial morbidity and mortality attributed to air pollution. Ultrafine particles, like those in diesel exhaust emissions, are a major source of nanoparticles in urban environments, and it is these particles that have the capacity to induce the most significant health effects. Research has shown that diesel exhaust exposure can have many detrimental effects on the cardiovascular system both acutely and chronically. This review provides an overview of the cardiovascular effects on PM in air pollution, with an emphasis on ultrafine particles in vehicle exhaust. We consider the biological mechanisms underlying these cardiovascular effects of PM and postulate that cardiovascular dysfunction may be implicated in the effects of PM in other organ systems. The employment of multiple strategies to tackle air pollution, and especially ultrafine particles from vehicles, is likely to be accompanied by improvements in cardiovascular health.

Pollutant gas and particulate material emissions in ethanol production in Brazil: social and environmental impacts

The replacement of fossil-based fuels by renewable fuels (biofuels) was proposed in the IPCC report, as an alternative to reduce greenhouse gas emission and reach out to a low-carbon economy. On this perspective, the Brazilian government had implemented a renewable energy program based on the use of ethanol in the transport sector. This work evaluates the scenario of pollutant gas emissions and particulate material that comes from the biomass burning process involved in ethanol production cycle, in the city of Campos dos Goytacazes, Brazil. The gases and particulate material emitted by sugarcane and bagasse burning processes-the last one in energy co-generation mills-were analyzed. A laboratory-controlled burning of both samples was realized in an oven with temperature ramp from 250 to 400 °C, at a regular rate of 50 °C. The gas samples were collected directly from the oven's exhaust pipe. The particulates obtained were the residual material taken out of the burned samples: a powder with the aspect of soot. A photoacoustic spectroscopy system coupled with quantum cascade laser and electrochemical analyzers was used to measure the emission of polluting gases such as N₂O, CO₂, CO, NO_x (NO, NO₂), and SO₂ in ppmv range. Fluorescent X-ray spectrometry was applied to evaluate the chemical composition of particulate material, enabling the identification of elements such as Si, Al, Ca, K, Fe, S, P, Ti, Mn, Cu, Zn, Sc, V, Cu, and Sr.

Effects of cooking oil fume derived fine particulate matter on blood vessel formation through the VEGF/VEGFR2/MEK1/2/ERK1/2/mTOR pathway in human umbilical vein endothelial cells

In China, cooking oil fume derived fine particulate matter (COF-derived PM_2.5) is a principal source of indoor air pollution. Here, we investigated cytotoxicity of COF-derived PM_2.5, as well as the roles of VEGF, VEGFR2, MEK1/2, ERK1/2, and mTOR cascade in the inhibitory effects of COF-derived PM_2.5, on angiogenesis in human umbilical vein endothelial cells (HUVECs). After exposure to COF-derived PM_2.5, cell viability and tube formation, as well as protein and mRNA levels of VEGF, VEGFR2, MEK1/2, ERK1/2, and mTOR in HUVECs were measured. Cell viability and number of tubes reduced dose-dependently after COF-derived PM2.5 and SU5416 treatment. In addition, SU5416 and VEGF significantly affected tube formation. The protein and mRNA levels of VEGF, VEGFR2, MEK1/2, ERK1/2, and mTOR all tended to reduce with the increase of COF-derived PM2.5 concentrations. These findings demonstrate that VEGF, VEGFR2, MEK1/2, ERK1/2, and mTOR play key roles in COF-derived PM_2.5 induced inhibition of angiogenesis in HUVECs.

The effects of cooking oil fumes-derived PM2.5 on blood vessel formation through ROS-mediated NLRP3 inflammasome pathway in human umbilical vein endothelial cells

BACKGROUND

Cooking oil fumes (COFs), a main pollutant in kitchen air, is a major risk to human health. In our previous research, exposure to COFs-derived PM_2.5 could cause umbilical vascular endothelial dysfunction, leading to decreased fetal weight. Here, to test the role of ROS-mediated NLRP3 inflammasome pathway in blood vessel formation of human umbilical vein endothelial cells (HUVECs) caused by COFs-derived PM_2.5, the cells were exposed to COFs-derived PM_2.5 at different concentrations with and without N-acetyl-L-cysteine (NAC).

METHODS

MTT assay was used to determine HUVECs viability. Intracellular ROS and mitochondrial ROS levels were assessed with DCFH-DA and MitoSOX™ assay. The levels of proteins and mRNA involved in NLRP3 inflammasome signaling pathway and VEGF were measured by western blot and real-time PCR (RT-PCR). Tube formation in HUVECs was detected by tube formation assay.

RESULTS

The results revealed that COFs-derived PM_2.5 exposure reduced HUVECs viability, increased the intracellular and mitochondrial ROS levels in cells, and up-regulated the levels of proteins and mRNA involved in NLRP3 inflammasome signaling pathway. However, the protein and mRNA expression of VEGF were reduced with the increasing exposure concentrations. In addition, COFs-derived PM_2.5 also affected the tube formation. However, co-incubation with NAC effectively rescued the damages caused by COFs-derived PM_2.5 exposure.

CONCLUSIONS

This study proved that COFs-derived PM_2.5 could significantly reduce HUVECs viability, induce the overproduction of ROS, lead to inflammation and inhibit VEGF expression, thus affect angiogenesis of HUVECs in vitro. It was revealed that the impact caused by COFs-derived PM_2.5 on blood vessel formation through a ROS-mediated NLRP3 inflammasome pathway.

Establishment of 3-dimensional scaffolds from hemochorial placentas

INTRODUCTION

The extracellular matrix (ECM) is a complex, tissue-specific 3-dimensional network that controls cell processes. ECMs derived from various organs are used to produce biological scaffolds comparable to the native microenvironment. Although placentas are often overlooked, they offer a rich ECM for tissue engineering, especially the hemochorial placentas from rodents and lagomorphs that resemble the ones from humans.

METHODS

Here we established a protocol for decellularization and investigated the ECM in native and decellularized placentas of guinea pigs, rats and rabbits by means of histology, immunohistochemistry, immunofluorescence and scanning electron microscopy.

RESULTS

Effective decellularization were achieved by immersion in 0.25% Sodium Dodecyl Sulfate for 3 days, resulting in an intact ECM, while cells or nuclei were absent. All species had a high diversity of ECM components that varied between areas.

DISCUSSION

Dense fibrous networks in the junctional zone were strongly positive to collagen I, III and IV, fibronectin, and laminin ECM markers. Noticeable response were also found for the decidua, especially along the maternal vessels. The labyrinth had thin fibers strongly positive for fibronectin and laminin, but not much for collagens. In conclusion, we established an effective protocol to obtain biological scaffolds from animal models with hemochorial placentas that possessed promising values for future purposes in Regenerative Medicine.

Exposure to coarse particulate matter during gestation and term low birthweight in California: Variation in exposure and risk across region and socioeconomic subgroup

Despite evidence that particulate matter with an aerodynamic diameter ≤10 μm (PM₁₀) or ≤2.5 μm (PM_2.5) are associated with several adverse birth outcomes, research on the association between coarse particulate matter (PM_10-2.5) and birth outcomes is scarce, and results have been inconsistent. Furthermore, the literature is unclear whether associations between PM₁₀ and adverse birth outcomes were driven by PM_2.5 alone or also by PM_10-2.5 exposure. Research on the variation in exposure to and risk from PM_10-2.5 across populations is also needed to identify potentially vulnerable subgroups. We used birth certificate and ambient air monitoring data in California from 2002 to 2013 to develop a retrospective cohort study of pregnant women and their infants. Averaged gestational and trimester-specific exposures of PM_10-2.5 and PM_2.5 were calculated for mothers whose residential zip code tabulation areas were within a 20 km radius of monitors. We assessed the relationship between prenatal exposure to PM_10-2.5 and term low birthweight (TLBW) using logistic and linear regression, adjusting for maternal and paternal demographic, environmental, temporal, and health-related covariates. We also conducted analyses stratified by socioeconomic characteristics and regions. We found a relationship between PM_10-2.5 exposure during pregnancy and TLBW after controlling for PM_2.5 exposure: odds ratio for second quartile of exposure: 1.00 (95% confidence interval: 0.98, 1.03), third quartile: 1.03 (1.00, 1.06), fourth quartile: 1.04 (1.01, 1.07), compared to the first quartile. Associations were strong among Non-Hispanic Black mothers, mothers living in the Central Valley, and fathers without a college degree. Exposure to and risk from PM_10-2.5 were heterogeneous across California indicating environmental justice implications. We also found that paternal characteristics were associated with the risk of TLBW even after controlling for maternal characteristics. In addition to PM_10-2.5 total mass, further research is needed on the components of PM_10-2.5 which may be driving these associations.

Analytical model of the feto-placental vascular system: consideration of placental oxygen transport

The placenta is a transient vascular organ that enables nutrients and blood gases to be exchanged between fetal and maternal circulations. Herein, the structure and oxygen diffusion across the trophoblast membrane between the fetal and maternal red blood cells in the feto-placental vasculature system in both human and mouse placentas are presented together as a functional unit. Previous models have claimed that the most efficient fetal blood flow relies upon structures containing a number of 'conductive' symmetrical branches, offering a path of minimal resistance that maximizes blood flow to the terminal villi, where oxygen diffusion occurs. However, most of these models have disregarded the actual descriptions of the exchange at the level of the intermediate and terminal villi. We are proposing a 'mixed model' whereby both 'conductive' and 'terminal' villi are presumed to be present at the end of single (in human) or multiple (in mouse) pregnancies. We predict an optimal number of 18 and 22 bifurcation levels in the human and the mouse placentas, respectively. Wherever possible, we have compared our model's predictions with experimental results reported in the literature and found close agreement between them.

Cause-specific stillbirth and exposure to chemical constituents and sources of fine particulate matter

The stillbirth rate in the United States is relatively high, but limited evidence is available linking stillbirth with fine particulate matter (PM_2.5), its chemical constituents and sources. In this study, we explored associations between cause-specific stillbirth and prenatal exposures to those pollutants with using live birth and stillbirth records from eight California locations during 2002-2009. ICD-10 codes were used to identify cause of stillbirth from stillbirth records. PM_2.5 total mass and chemical constituents were collected from ambient monitors and PM_2.5 sources were quantified using Positive Matrix Factorization. Conditional logistic regression was applied using a nested case-control study design (N = 32,262). We found that different causes of stillbirth were associated with different PM_2.5 sources and/or chemical constituents. For stillbirths due to fetal growth, the odds ratio (OR) per interquartile range increase in gestational age-adjusted exposure to PM_2.5 total mass was 1.23 (95% confidence interval (CI): 1.06, 1.44). Similar associations were found with resuspended soil (OR=1.25, 95% CI: 1.10, 1.42), and secondary ammonium sulfate (OR=1.45, 95% CI: 1.18, 1.78). No associations were found between any pollutants and stillbirths caused by maternal complications. This study highlighted the importance of investigating cause-specific stillbirth and the differential toxicity levels of specific PM_2.5 sources and chemical constituents.

ROS-AKT-mTOR axis mediates autophagy of human umbilical vein endothelial cells induced by cooking oil fumes-derived fine particulate matters in vitro

Cooking oil fumes-derived PM_2.5 (COFs-derived PM_2.5) exposure can induce oxidative stress and cytotoxic effects. Here we investigated the role of ROS-AKT-mTOR axis in COFs-derived PM_2.5-induced autophagy in human umbilical vein endothelial cells (HUVECs). HUVECs were treated with different concentrations of COFs-derived PM_2.5, together with or without N-acetyl-L-cysteine (NAC, a radical scavenger) or 3-methyladenine (3-MA, an autophagy inhibitor). Cell viability was assessed with MTT assay, and ROS level was measured with DCFH-DA assay after the treatment. Transmission electron microscopy (TEM) was used to evaluate the formation of autophagosomes, while immunofluorescent assay and western blot were used to assess the expression of LC3-I/II and beclin 1. Proteins involved in the PI3K-AKT-mTOR signaling pathway were measured with western blot. The results showed that the treatment of COFs-derived PM_2.5 dose-dependently reduced the viability of HUVECs and increased the ROS levels in the cells. Both immunofluorescent assay and western blot showed that treatment with COFs-derived PM_2.5 significantly increased LC3-II and beclin 1 levels, as well as the ratio of LC3-II/LC3-I, which could be rescued by the co-incubation with NAC or 3-MA. TEM also confirmed the increased formation of autophagosomes in the cells treated with COFs-derived PM_2.5, while co-treatment with NAC evidently decreased autophagosomes formation. In addition, western blot also showed that the phosphorylation of PI3K, AKT, and mTOR all decreased by the treatment of COFs-derived PM_2.5, which was effectively rescued by the co-treatment with NAC. These findings demonstrate ROS-AKT-mTOR axis plays a critical role in HUVECs autophagy induced by COFs-derived PM_2.5.

The injury of fine particulate matter from cooking oil fumes on umbilical cord blood vessels in vitro

Cooking oil fumes (COFs) derived PM_2.5 is the major source of indoor air pollution in Asia. For this, a pregnant rat model within different doses of cooking oil fumes (COFs) derived PM_2.5 was established in pregnancy in our research. Our previous studies have showed that exposure to COFs-derived PM_2.5 was related to adverse pregnancy outcomes. However, the mechanisms of signaling pathways remain unknown. Therefore, this study aimed to investigate the underlying mechanisms induced by COFs-derived PM2.5 injury on umbilical cord blood vessels (UCs) in vitro. Exposure to COFs-derived PM_2.5 resulted in changing the expression of eNOS, ET-1, ETRA, and ETRB. In additions, western blot analysis indicated that the HIF-1α/iNOS/NO signaling pathway and VEGF/VEGFR1/iNOS signaling pathway were involved in UCs injury triggered by COFs-derived PM_2.5. In conclusion, our data suggested that exposure to COFs-derived PM_2.5 resulted in increasing of oxidative stress and inflammation, as well as dysfunction of UCs.

PM2.5 induces embryonic growth retardation: Potential involvement of ROS-MAPKs-apoptosis and G0/G1 arrest pathways

Airborne fine particulate matter (PM_2.5 ) is an "invisible killer" to human health. There is increasing evidence revealing the adverse effects of PM_2.5 on the early embryonic development and pregnancy outcome, but the molecular mechanism underlying PM_2.5 -induced embryotoxicity is largely unknown. Previous studies have documented that exposure to PM triggers ROS generation, leads to subsequent activation of MAPKs signaling, and results in corresponding cell biological changes including enhanced apoptosis and altered cell cycle in the cardiopulmonary system. Here, we investigated whether ROS-MAPKs-apoptosis/cell cycle arrest pathways play an important role in PM_2.5 -induced embryotoxicity using the rat whole embryo culture system. The results showed that PM_2.5 treatment led to embryonic growth retardation at concentrations of 50 μg/ml and above, as evidenced by the reduced yolk sac diameter, crown-rump length, head length and somite number. PM_2.5 -induced embryonic growth retardation was accompanied by cell apoptosis and G0/G1 phase arrest. Furthermore, ROS generation and subsequent activation of JNK and ERK might be involved in PM_2.5 -induced apoptosis and G0/G1 phase arrest by downregulating Bcl-2/Bax protein ratio and upregulating p15^INK4B , p16^INK4A , and p21^WAF1/CIP1 transcription level. In conclusion, our results indicate that ROS-JNK/ERK-apoptosis and G0/G1 arrest pathways are involved in PM_2.5 -induced embryotoxicity, which not only provides insights into the molecular mechanism of PM_2.5 -induced embryotoxicity, but also may help to identify specific interventions to improve adverse pregnancy outcomes of PM_2.5 . © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 2028-2044, 2016.

The structural and functional effects of fine particulate matter from cooking oil fumes on rat umbilical cord blood vessels

A growing body of epidemiological evidence has supported the association between maternal exposure to airborne fine particulate matter (PM2.5) during pregnancy and adverse pregnancy outcomes. However, the specific biological mechanisms implicated in the causes of adverse pregnancy outcomes are not well defined. In this study, a pregnant rat model of exposure to different doses of cooking oil fumes (COFs)-derived PM2.5 by tail intravenous injection in different pregnant stages was established. The results indicated that exposure to COFs-derived PM2.5 was associated with adverse pregnancy outcomes, changed the structure of umbilical cord blood vessels, decreased the diameter and lumen area, and increased wall thickness. What's more, a significant increase of maximum contraction tension was observed in the early pregnancy high-dose exposure group and pregnant low-dose exposure group compared to the control group. Based on the maximum contraction tension, acetylcholine (ACh) did not induce vasodilation but caused a dose-dependent constriction, and there were significant differences in the two groups compared to the control group. Exposure to COFs-derived PM2.5 impaired the vasomotor function of umbilical veins by affecting the expression of NO and ET-1. This is the first study that evaluated the association of risk of adverse pregnancy outcomes and pregnant rats exposed to COFs-derived PM2.5 and primarily explored the potential mechanisms of umbilical cord blood vessels injury on a rat model. More detailed vitro and vivo studies are needed to further explore the mechanism in the future.

Associations of maternal personal exposure to air pollution on fetal weight and fetoplacental Doppler: A prospective cohort study

We determined the influence of maternal air pollution exposure during each trimester of pregnancy on fetal and birth weight and fetoplacental hemodynamics. In total, 366 women with singleton pregnancies were prospectively followed in the city of São Paulo, Brazil. Nitrogen dioxide (NO2) and ozone (O3) were measured during each trimester using passive personal samplers. We evaluated fetal weight and Doppler velocimetry data from the umbilical, middle cerebral, and uterine arteries in the 3rd trimester, and birth weight. Multivariate analysis was performed, controlling for known determinants of fetal weight. Exposure to higher levels of O3 during the 2nd trimester was associated with higher umbilical artery pulsatility indices (PIs) [p=0.013; beta=0.017: standard error (SE)=0.007]. Exposure to higher levels of O3 during the 3rd trimester was associated with lower umbilical artery PIs (p=0.011; beta=-0.021; SE=0.008). Our results suggest that in the environment of São Paulo, O3 may affects placental vascular resistance.

Exposure to fine particulate matter during pregnancy and risk of preterm birth among women in New Jersey, Ohio, and Pennsylvania, 2000-2005

BACKGROUND

Particulate matter ≤ 2.5 μm in aerodynamic diameter (PM2.5) has been variably associated with preterm birth (PTB).

OBJECTIVE

We classified PTB into four categories (20-27, 28-31, 32-34, and 35-36 weeks completed gestation) and estimated risk differences (RDs) for each category in association with a 1-μg/m3 increase in PM2.5 exposure during each week of gestation.

METHODS

We assembled a cohort of singleton pregnancies that completed ≥ 20 weeks of gestation during 2000-2005 using live birth certificate data from three states (Pennsylvania, Ohio, and New Jersey) (n = 1,940,213; 8% PTB). We estimated mean PM2.5 exposures for each week of gestation from monitor-corrected Community Multi-Scale Air Quality modeling data. RDs were estimated using modified Poisson linear regression and adjusted for maternal race/ethnicity, marital status, education, age, and ozone.

RESULTS

RD estimates varied by exposure window and outcome period. Average PM2.5 exposure during the fourth week of gestation was positively associated with all PTB outcomes, although magnitude varied by PTB category [e.g., for a 1-μg/m3 increase, RD = 11.8 (95% CI: -6, 29.2); RD = 46 (95% CI: 23.2, 68.9); RD = 61.1 (95% CI: 22.6, 99.7); and RD = 28.5 (95% CI: -39, 95.7) for preterm births during 20-27, 28-31, 32-34, and 35-36 weeks, respectively]. Exposures during the week of birth and the 2 weeks before birth also were positively associated with all PTB categories.

CONCLUSIONS

Exposures beginning around the time of implantation and near birth appeared to be more strongly associated with PTB than exposures during other time periods. Because particulate matter exposure is ubiquitous, evidence of effects of PM2.5 exposure on PTB, even if small in magnitude, is cause for concern.

Flavonol-rich dark cocoa significantly decreases plasma endothelin-1 and improves cognition in urban children

Air pollution exposures are linked to systemic inflammation, cardiovascular and respiratory morbidity and mortality, neuroinflammation and neuropathology in young urbanites. In particular, most Mexico City Metropolitan Area (MCMA) children exhibit subtle cognitive deficits, and neuropathology studies show 40% of them exhibiting frontal tau hyperphosphorylation and 51% amyloid-β diffuse plaques (compared to 0% in low pollution control children). We assessed whether a short cocoa intervention can be effective in decreasing plasma endothelin 1 (ET-1) and/or inflammatory mediators in MCMA children. Thirty gram of dark cocoa with 680 mg of total flavonols were given daily for 10.11 ± 3.4 days (range 9–24 days) to 18 children (10.55 years, SD = 1.45; 11F/7M). Key metabolite ratios in frontal white matter and in hippocampus pre and during cocoa intervention were quantified by magnetic resonance spectroscopy. ET-1 significantly decreased after cocoa treatment (p = 0.0002). Fifteen children (83%) showed a marginally significant individual improvement in one or both of the applied simple short memory tasks. Endothelial dysfunction is a key feature of exposure to particulate matter (PM) and decreased endothelin-1 bioavailability is likely useful for brain function in the context of air pollution. Our findings suggest that cocoa interventions may be critical for early implementation of neuroprotection of highly exposed urban children. Multi-domain nutraceutical interventions could limit the risk for endothelial dysfunction, cerebral hypoperfusion, neuroinflammation, cognitive deficits, structural volumetric detrimental brain effects, and the early development of the neuropathological hallmarks of Alzheimer's and Parkinson's diseases.