Maternal exposure to ambient air pollution during pregnancy and lipid profile in umbilical cord blood samples; a cross-sectional study

The association of in-utero exposure to air pollution and atherogenic index of plasma in newborns

BACKGROUND

Prenatal exposure to particulate matter (PM) and traffic was associated with the programming of cardiovascular diseases (CVDs) in early life. However, the exact underlying mechanisms are not fully understood. Therefore, we aimed to evaluate the association between in-utero exposure to PMs and traffic indicators with the atherogenic index of plasma (AIP) in newborns, which is a precise index reflecting an enhancement of lipid risk factors for CVDs.

METHODS

In this cross-sectional study, a total of 300 mother-newborn pairs were enrolled in Sabzevar, Iran. Spatiotemporal land-use regression models were used to estimate the level of PM1, PM2.5 and PM10 at the mother's residential address. The total length of streets in different buffers (100,300 and 500m) and proximity to major roads were calculated as indicators of traffic. The AIP of cord blood samples was calculated using an AIP calculator. Multiple linear regression models were used to examine the association of PM concentrations as well as traffic indicators with AIP controlled for relevant covariates.

RESULTS

PM2.5 exposure was significantly associated with higher levels of AIP in newborns. Each interquartile range (IQR) increment of PM2.5 concentration at the mothers' residential addresses was associated with a 5.3% (95% confidence interval (CI): 0.0, 10.6%, P = 0.04) increase in the AIP. Associations between PM1, PM10 and traffic indicators with cord blood level of AIP were positive but not statistically significant.

CONCLUSION

Our findings showed that in utero exposure to PM2.5 may be associated with CVDs programming through the increase of atherogenic lipids.

Exposure to ambient air pollutants, serum miRNA networks, lipid metabolism, and non-alcoholic fatty liver disease in young adults

BACKGROUND AND AIM

Ambient air pollution (AAP) exposure has been associated with altered blood lipids and liver fat in young adults. MicroRNAs regulate gene expression and may mediate these relationships. This work investigated associations between AAP exposure, serum microRNA networks, lipid profiles, and non-alcoholic fatty liver disease (NAFLD) risk in young adults.

METHODS

Participants were 170 young adults (17-22 years) from the Meta-AIR cohort of the Children's Health Study (CHS). Residential AAP exposure (PM2.5, PM10, NO2, 8-hour maximum O3, redox-weighted oxidative capacity [Oxwt]) was spatially interpolated from monitoring stations via inverse-distance-squared weighting. Fasting serum lipids were assayed. Liver fat was imaged by MRI and NAFLD was defined by ≥ 5.5% hepatic fat fraction. Serum microRNAs were measured via NanoString and microRNA networks were constructed by weighted gene correlation network analysis. The first principal component of each network represented its expression profile. Multivariable mixed effects regression models adjusted for sociodemographic, behavioral, and clinical covariates; baseline CHS town code was a random effect. Effects estimates are scaled to one standard deviation of exposure. Mediation analysis explored microRNA profiles as potential mediators of exposure-outcome associations. DIANA-mirPATH identified overrepresented gene pathways targeted by miRNA networks.

RESULTS

Prior-month Oxwt was associated with NAFLD (OR=3.45; p = 0.003) and inversely associated with microRNA Network A (β = -0.016; p = 0.026). Prior-year NO2 was associated with non-HDL-cholesterol (β = 7.13; p = 0.01) and inversely associated with miRNA Network A (β = -0.019; p = 0.022). Network A expression was inversely associated with NAFLD (OR=0.35; p = 0.010) and non-HDL-C (β = -6.94 mg/dL; p = 0.035). Network A members miR-199a/b-3p and miR-130a, which both target fatty acid synthase, mediated 21% of the association between prior-month Oxwt exposure with NAFLD (p = 0.048) and 23.3% of the association between prior-year NO2 exposure and non-HDL-cholesterol (p = 0.026), respectively.

CONCLUSIONS

Exposure to AAP may contribute to adverse lipid profiles and NAFLD risk among young adults via altered expression of microRNA profiles.

Independent and interactive associations between greenness and ambient pollutants on novel glycolipid metabolism biomarkers: A national repeated measurement study

This study aims to investigate the independent and interactive effects of greenness and ambient pollutants on novel glycolipid metabolism biomarkers. A repeated national cohort study was conducted among 5085 adults from 150 counties/districts across China, with levels of novel glycolipid metabolism biomarkers of TyG index, TG/HDL-c, TC/HDL-c, and non-HDL-c measured. Exposure levels of greenness and ambient pollutants (including PM1, PM2.5, PM10, and NO2) for each participant were determined based on their residential location. Linear mixed-effect and interactive models were used to evaluate the independent and interactive effects between greenness and ambient pollutants on the four novel glycolipid metabolism biomarkers. In the main models, the changes [β (95% CIs)] of TyG index, TG/HDL-c, TC/HDL-c, and non-HDL-c were -0.021 (-0.036, -0.007), -0.120 (-0.175, -0.066), -0.092 (-0.122, -0.062), and -0.445 (-1.370, 0.480) for every 0.1 increase in NDVI, and were 0.004 (0.003, 0.005), 0.014 (0.009, 0.019), 0.009 (0.006, 0.011), and 0.067 (-0.019, 0.154) for every 1 μg/m3 increase in PM1. Results of interactive analyses demonstrated that individuals living in low-polluted areas could get greater benefits from greenness than those living in highly-polluted areas. Additionally, the results of mediation analyses revealed that PM2.5 mediated 14.40% of the association between greenness and the TyG index. Further research is needed to validate our findings.

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 associations of particulate matter short-term exposure and serum lipids are modified by vitamin D status: A panel study of young healthy adults

Particulate matter (PM) exposure is associated to the adverse change in blood lipids. Vitamin D is beneficial to lipid metabolism, but whether vitamin D levels modifies the impact of air pollutants on lipids is unclear. The purpose of the study was to investigate if vitamin D modifies the associations of PM and serum lipids in young healthy people. From December 2017 to January 2018, a panel study with five once weekly follow-ups was conducted on 88 healthy adults aged 21.09 (1.08) (mean (SD)) years on average in Guangzhou, China. We measured serum lipids, serum 25-hydroxyvitamin D (25(OH)D) concentrations (440 blood samples in total), mass concentrations of particulate matter with diameters ≤2.5 μm (PM_2.5), ≤1.0 μm (PM_1.0), and ≤0.5 μm (PM_0.5), and number concentrations of particulate matter with diameters ≤0.2 μm (PN_0.2) and ≤0.1 μm (PN_0.1) at each follow-up. Linear mixed-effect models were applied to assess the interaction of vitamin D and size-fractionated PM short-term exposure on four lipid metrics. We found the interactions between 25(OH)D and size-fractionated PM exposure on blood lipids in different lags (lag 3 days and 4 days). An interquartile range increase in PM_2.5, PM_1.0, PM_0.5 were significantly associated with increments of 12.30%, 12.99%, and 13.66% in triglycerides (TGs) at lag 4 days at vitamin D levels <15 ng/mL group, respectively. Similar results were found for PN_0.2, PN_0.1 and low-density lipoprotein cholesterol (LDL-C). All the associations between size-fractionated PM and blood lipids were found null statistically significant in vitamin D levels ≥15 ng/mL group.

Effects of ambient particulate exposure on blood lipid levels in hypertension inpatients

Background

With modernization development, multiple studies of atmospheric particulate matter exposure conducted in China have confirmed adverse cardiovascular health effects. However, there are few studies on the effect of particulate matter on blood lipid levels in patients with cardiovascular disease, especially in southern China. The purpose of this study was to investigate the association between short- and long-term exposure to ambient particulate matter and the levels of blood lipid markers in hypertension inpatients in Ganzhou, China.

Methods

Data on admission lipid index testing for hypertension inpatients which were divided into those with and without arteriosclerosis disease were extracted from the hospital's big data center from January 1, 2016 to December 31, 2020, and air pollution and meteorology data were acquired from the China urban air quality real time release platform from January 1, 2015 to December 31, 2020 and climatic data center from January 1, 2016 to December 31, 2020, with data integrated according to patient admission dates. A semi-parametric generalized additive model (GAM) was established to calculate the association between ambient particulate matter and blood lipid markers in hypertension inpatients with different exposure time in 1 year.

Results

Long-term exposure to particulate matter was associated with increased Lp(a) in three kinds of people, and with increased TC and decreased HDL-C in total hypertension and hypertension with arteriosclerosis. But particulate matter was associated with increased HDL-C for hypertension inpatients without arteriosclerosis, at the time of exposure in the present study. It is speculated that hypertension inpatients without arteriosclerosis has better statement than hypertension inpatients with arteriosclerosis on human lipid metabolism.

Conclusion

Long-term exposure to ambient particulate matter is associated with adverse lipid profile changes in hypertension inpatients, especially those with arteriosclerosis. Ambient particulate matter may increase the risk of arteriosclerotic events in hypertensive patients.

A study on exposure to greenspace during pregnancy and lipid profile in cord blood samples

Although evidence reporting the beneficial associations of prenatal greenspace exposure with pregnancy outcomes is increasing, there is still a lack of evidence on the potential association of such exposure to greenspace on fetal lipid profile. We aimed to first-time investigate the associations between prenatal exposure to greenspace and lipid levels in the cord blood. The present study was based on data from 150 expectant mothers, residents of Sabzevar city in Iran (2018). For each participant, we identified exposure to greenspace in residential surroundings, residential accessibility to green space, use of green spaces, and the number of plant pots inside the home. Measures of levels of triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and TC/HDL-C and TG/HDL-C ratios in samples of cord blood were applied to identify the lipid profile. We developed adjusted linear regression models to estimate the associations of each indicator of greenspace exposure with each cord blood lipid. We found increased greenspace in residential surroundings across a 100 m buffer, higher residential accessibility to green space, and more use of green spaces were associated with decreased cord blood lipid levels. The remainder findings regarding the greenspace in residential surroundings across 300 m and 500 m buffers and the number of plant pots were null. Some suggestions were observed for a potential mediatory role of air pollution. This study suggests that greenspace exposure during pregnancy may influence positively fetal lipid levels in the cord blood.

Ambient air pollution during pregnancy and cardiometabolic biomarkers in cord blood

Prenatal air pollution exposure has been associated with adverse childhood cardiometabolic outcomes. It is unknown whether evidence of metabolic disruption associated with air pollution is identifiable at birth. We examined exposure to prenatal ambient air pollution and cord blood cardiometabolic biomarkers among 812 mother-infant pairs in the Healthy Start study.

Prenatal exposure to traffic-related air pollution and glucose homeostasis: A cross-sectional study

Air pollution exposure has been linked with glucose dysregulation in pregnant women; however, evidence on these associations with fetal glucose homeostasis is unclear yet. We therefore aimed to evaluate the association of prenatal exposure to particulate matter (PM) and traffic indicators with fetal glucose homeostasis in cord blood samples. A total of 169 mother-infant pairs recruited from Mobini hospital of Sabzevar, Iran, were included in this cross-sectional study. Maternal exposure to PMs was estimated using land use regression models. Moreover, traffic indicators (i.e., total street length in 100, 300 and 500 m buffers and distance from residential home to the nearest major roads) were calculated based on the street map of Sabzevar. Cord blood glucose and insulin concentrations, HOMA-ꞵ, HOMA-S and HOMA-IR were used as glucose homeostasis markers. Higher maternal exposure to PM_2.5 and PM₁₀ were associated with higher cord blood glucose and insulin concentrations and HOMA-IR. Moreover, total streets length in 300 m buffer was positively associated with cord blood glucose and insulin concentrations and HOMA-IR. An increase in distance to major roads was associated with higher HOMA-ꞵ and HOMA-S and lower cord blood glucose and insulin concentrations as well as HOMA-IR. Overall, we found prenatal exposure to PMs and traffic indicators was associated with a higher risk of glucose homeostasis dysregulation in the fetus.

Foetal 25-hydroxyvitamin D moderates the association of prenatal air pollution exposure with foetal glucolipid metabolism disorder and systemic inflammatory responses

BACKGROUND

Previous studies have indicated that systemic inflammation may play an important role in the association between air pollution exposure and glucolipid metabolism disorders, and vitamin D supplementation was beneficial in improving systemic inflammation and glucolipid metabolism. However, the role of foetal 25-hydroxyvitamin D (25(OH)D) and high-sensitivity C-reactive protein (hs-CRP) in the association between prenatal air pollution exposure and foetal glucolipid metabolism disorders is still not clear.

OBJECTIVE

To verify whether foetal 25(OH)D can improve glucolipid metabolism disorders induced by prenatal air pollution exposure by inhibiting the systemic inflammation.

METHODS

A total of 2,754 mother-newborn pairs were enrolled from three hospitals in Hefei city, China, between 2015 and 2019. We obtained air pollutants (PM_2.5, PM₁₀, SO₂, CO, and NO₂) data from the Hefei City Ecology and Environment Bureau. Cord blood biomarkers (25(OH)D, hs-CRP, C-peptide, HDL-C, LDL-C, TC, and TG) were measured.

RESULTS

We found that prenatal air pollution exposure was positively associated with foetal glucolipid metabolic index levels after adjusting for confounders. Additionally, an IQR increase in exposure to PM_2.5, PM₁₀, SO₂, and CO was associated with 20.0% (95% confidence interval (CI): 16.9, 23.6), 20.1% (16.8, 23.3), 22.9% (20.6, 25.3), and 16.7% (14.4, 19.0) higher cord blood hs-CRP levels, respectively, and an SD increase in hs-CRP was associated with 1.4% (0.1, 2.8), 2.2% (1.6, 2.9), 1.4% (0.9, 2.0), and 3.9% (2.8, 4.9) higher C-peptide, LDL-C, TC, and TG levels in the cord blood, respectively. However, there was a monotonic decrease in βs between cord blood 25(OH)D and biomarkers (P for trend < 0.001). Furthermore, mediation analysis revealed that the association between air pollution exposure and foetal glucolipid metabolic indexes mediated by hs-CRP and 25(OH)D was 19.35%. In stratified analyses, the significant negative association between cord blood 25(OH)D with foetal hs-CRP and glucolipid metabolic indexes was observed only at low-medium levels of air pollution exposure.

CONCLUSIONS

Prenatal air pollution exposure could damage foetal glucolipid metabolic function through systemic inflammation. High foetal 25(OH)D levels may improve foetal systemic inflammation and glucolipid metabolism at low-medium levels of prenatal air pollution exposure.

Maternal exposure to air pollution and umbilical asprosin concentration, a novel insulin-resistant marker

Air pollution exposure during pregnancy has been associated with abnormal glucose hemostasis in the fetus, which may result in the programming of type 2 diabetes mellitus (T2DM) development in future life. Therefore, we investigated the association of maternal exposure to particulate matters (PMs) and traffic indicators with umbilical asprosin concentration, a novel insulin-resistant inducing adipokine, in newborns. Accordingly, 759 mother-newborn pairs from Sabzevar, Iran (2018-2019) participated in our study. Maternal exposure to PM₁, PM_2.5 and PM₁₀ concentrations was estimated using spatial-temporal models developed for the study area. The associations of exposure to traffic indicators (total street length in 100, 300 and 500 m buffers around home and proximity of mothers to nearest major roads) and air pollution with umbilical asprosin concentration were estimated using linear regression models, adjusted for potential confounders. The median (interquartile range (IQR)) of umbilical asprosin concentration was 30.4 (19.1) ng/mL. In fully adjusted models, each one IQR increase in PM₁₀ and PM_2.5 were associated with 26.43 ng/mL (95% CI: 10.97, 41.88) and 31.76 ng/mL (95% CI: 15.66, 47.86) increase in umbilical asprosin concentration, respectively. A similarity result was observed for total street length in 100 m buffer. An increase in proximity to major roads was associated with a decrease of -21.48 ng/mL (95% CI: 33.29, -9.67) in umbilical asprosin concentration. Our results suggested that maternal exposure to air pollution during pregnancy could increase the umbilical asprosin concentration. These novel findings may improve our understanding of the mechanisms whereby air pollutants impaired glucose hemostasis during the fetal period.

Early-life exposure to submicron particulate air pollution in relation to asthma development in Chinese preschool children

BACKGROUND

Emerging research suggested an association of early-life particulate air pollution exposure with development of asthma in childhood. However, the potentially differential effects of submicron particulate matter (PM; PM with aerodynamic diameter ≤1 μm [PM₁]) remain largely unknown.

OBJECTIVE

This study primarily aimed to investigate associations of childhood asthma and wheezing with in utero and first-year exposures to size-specific particles.

METHODS

We conducted a large cross-sectional survey among 5788 preschool children aged 3 to 5 years in central China. In utero and first-year exposures to ambient PM₁, PM with aerodynamic diameter less than or equal to 2.5 μm, and PM with aerodynamic diameter less than or equal to 10 μm at 1 × 1-km resolution were assessed using machine learning-based spatiotemporal models. A time-to-event analysis was performed to examine associations between residential PM exposures and childhood onset of asthma and wheezing.

RESULTS

Early-life size-specific PM exposures, particularly during pregnancy, were significantly associated with increased risk of asthma, whereas no evident PM-wheezing associations were observed. Each 10-μg/m³ increase in in utero and first-year PM₁ exposure was accordingly associated with an asthma's hazard ratio in childhood of 1.618 (95% CI, 1.159-2.258; P = .005) and 1.543 (0.822-2.896; P = .177). Subgroup analyses suggest that short breast-feeding duration may aggravate PM-associated risk of childhood asthma. Each 10-μg/m³ increase in in utero exposure to PM₁, for instance, was associated with a hazard ratio of 2.260 (1.393-3.666) among children with 0 to 5 months' breast-feeding and 1.156 (0.721-1.853) among those longer breast-fed.

CONCLUSIONS

Our study added comparative evidence for increased risk of childhood asthma in relation to early-life PM exposures, highlighting stronger associations with ambient PM₁ than with PM with aerodynamic diameter less than or equal to 2.5 μm and PM with aerodynamic diameter less than or equal to 10 μm.

Pre-pregnancy exposure to fine particulate matter (PM2.5) increases reactive oxygen species production in oocytes and decrease litter size and weight in mice

Exposure of females to fine particulate matter ≤2.5 μm in diameter (PM2.5) prior to pregnancy could produce adverse impact on fertility and enhances susceptibility of the offspring to a variety of diseases. In the current study, female C57BL/6 mice (6 weeks of age) were exposed to either concentrated PM2.5 or filtered air (average PM2.5 concentration: 115.60 ± 7.77 vs. 14.07 ± 0.38 μg/m^-3) using a whole-body exposure device for 12 weeks. Briefly, PM2.5 exposure decreased anti-Müllerian hormone level (613.40 ± 17.36 vs 759.30 ± 21.90 pg mL^-1, P＜0.01) and increased reactive oxygen species (ROS) level (45.39 ± 0.82 vs 24.20 ± 0.85 arbitrary unit in fluorescence assay, P＜0.01) in oocytes. The exposure increased oocyte degeneration rate (21.5% vs 5.1%, respectively (P＜0.01) and decreased the 2-cell formation rate (71.9% vs 86.0%, P < 0.01). Transcriptome profiling using RNA sequencing showed wide spectrum of abnormal expression of genes, particularly those involved in regulating the mitochondrial respiratory complex in oocytes and metabolic processes in blastocysts. The exposure decreased litter size (6 ± 0.37 vs 7 ± 0.26, P＜0.05) and weight (1.18 ± 0.02 vs 1.27 ± 0.02 g, P＜0.01). In summary, PM2.5 exposure decreased female fertility, possibly through increased ROS production in oocytes and metabolic disturbances in developing embryos. The cause-effect relationship, however, requires further investigation.

Preconception air pollution exposure and glucose tolerance in healthy pregnant women in a middle-income country

BACKGROUND

Preconception exposure to air pollution has been associated with glucose tolerance during pregnancy. However, the evidence in low and middle-income countries (LMICs) is under debate yet. Therefore, this study aimed to assess the relationship between exposure to ambient particulate matter (PM) and traffic indicators with glucose tolerance in healthy pregnant women in Sabzevar, Iran (2019).

METHODS

Two-hundred and fifty healthy pregnant women with singleton pregnancies and 24-26 weeks of gestations participated in our study. Land use regression (LUR) models were applied to estimate the annual mean of PM1, PM2.5 and PM10 at the residential address. Traffic indicators, including proximity of women to major roads as well as total streets length in 100, 300 and 500 m buffers around the home were calculated using the street map of Sabzevar. The oral glucose tolerance test (OGTT) was used to assess glucose tolerance during pregnancy. Multiple linear regression adjusted for relevant covariates was used to estimate the association of fasting blood glucose (FBG), 1-h and 2-h post-load glucose with PMs and traffic indicators.

RESULTS

Exposure to PM1, PM2.5 and PM10 was significantly associated with higher FBG concentration. Higher total streets length in a 100 m buffer was associated with higher FBG and 1-h glucose concentrations. An interquartile range (IQR) increase in proximity to major roads was associated with a decrease of - 3.29 mg/dL (95% confidence interval (CI): - 4.35, - 2.23, P-value < 0.01) in FBG level and - 3.65 mg/dL (95% CI, - 7.01, - 0.28, P-value = 0.03) decrease in 1-h post-load glucose.

CONCLUSION

We found that higher preconception exposure to air pollution was associated with higher FBG and 1-h glucose concentrations during pregnancy.

Exposure to wood smoke particles leads to inflammation, disrupted proliferation and damage to cellular structures in a human first trimester trophoblast cell line

The ongoing transition to renewable fuel sources has led to increased use of wood and other biomass fuels. The physiochemical characteristics of biomass combustion derived aerosols depends on appliances, fuel and operation procedures, and particles generated during incomplete combustion are linked to toxicity. Frequent indoor wood burning is related to severe health problems such as negative effects on airways and inflammation, as well as chronic hypoxia and pathological changes in placentas, adverse pregnancy outcome, preterm delivery and increased risk of preeclampsia. The presence of combustion-derived black carbon particles at both the maternal and fetal side of placentas suggests that particles can reach the fetus. Air pollution particles have also been shown to inhibit trophoblast migration and invasion, which are vital functions for the development of the placenta during the first trimester. In this study we exposed a placental first trimester trophoblast cell line to wood smoke particles emitted under Nominal Burn rate (NB) or High Burn rate (HB). The particles were visible inside exposed cells and localized to the mitochondria, causing ultrastructural changes in mitochondria and endoplasmic reticulum. Exposed cells showed decreased secretion of the pregnancy marker human chorionic gonadotropin, increased secretion of IL-6, disrupted membrane integrity, disrupted proliferation and contained specific polycyclic aromatic hydrocarbons (PAHs) from the particles. Taken together, these results suggest that wood smoke particles can enter trophoblasts and have detrimental effects early in pregnancy by disrupting critical trophoblast functions needed for normal placenta development and function. This could contribute to the underlying mechanisms leading to pregnancy complications such as miscarriage, premature birth, preeclampsia and/or fetal growth restriction. This study support the general recommendation that more efficient combustion technologies and burning practices should be adopted to reduce some of the toxicity generated during wood burning.

Real-ambient exposure to air pollution exaggerates excessive growth of adipose tissue modulated by Nrf2 signal

Air pollution was becoming a global threat to the public health, which was primarily mediated by PM_2.5 induced cardiovascular diseases and pulmonary diseases. Recently, observational epidemiologic studies proposed the link between PM_2.5 and obesity. Consistently, the link was also supported by limited animal researches. However, the potential mechanism mediating the harmful effects of PM_2.5 was still elusive. In this study, we applied the "real-ambient exposure" system to conduct the experiments, which was closer to the status of ambient air pollution compared with the method of intratracheal instillation and concentrated air particles (CAPs) exposure system. Nuclear factor E2-related factor 2 (Nrf2) was previously reported to protect against inflammation and oxidative stress when exposed to PM_2.5. Here, we reported that Nrf2^-/- mice developed overgrowth of adipose tissue after "real-ambient exposure" to PM_2.5, compared to filtered air (FA) group. Consistently, compared to FA group, adipocytes from subcutaneous (sWAT) and gonadal (gWAT) white adipose tissue of Nrf2^-/- mice exhibited enlarged cell size in PM_2.5 exposure group. Furthermore, the levels of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) in serum and liver of Nrf2^-/- mice were also altered statistically in PM_2.5 exposure group. Importantly, when the expression of lipogenic enzymes was analyzed, the levels of the related specific genes in adipose tissue and liver of Nrf2^-/- mice were altered in PM_2.5 exposure group. Interestingly, the key transcription factors modulating expression of lipogenic enzymes in liver of Nrf2^-/- mice were also found altered in PM_2.5 exposure group, such as peroxisome proliferator-activated receptor (PPARα, PPARγ). Taken together, our study mimicked the status of ambient air pollution, revealed new insights into the adverse effect of PM_2.5 exposure, provided new link between air pollution and overgrowth of adipose tissue, and supported the vital role of Nrf2 in mediating the side effects of PM_2.5.