Prenatal O3 exposure increases the severity of OVA-induced asthma in offspring

Associations of prenatal ambient air pollution exposures with asthma in middle childhood

We examined associations between prenatal fine particulate matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3) exposures and child respiratory outcomes through age 8-9 years in 1279 ECHO-PATHWAYS Consortium mother-child dyads. We averaged spatiotemporally modeled air pollutant exposures during four fetal lung development phases: pseudoglandular (5-16 weeks), canalicular (16-24 weeks), saccular (24-36 weeks), and alveolar (36+ weeks). We estimated adjusted relative risks (RR) for current asthma at age 8-9 and asthma with recent exacerbation or atopic disease, and odds ratios (OR) for wheezing trajectories using modified Poisson and multinomial logistic regression, respectively. Effect modification by child sex, maternal asthma, and prenatal environmental tobacco smoke was explored. Across all outcomes, 95% confidence intervals (CI) included the null for all estimates of associations between prenatal air pollution exposures and respiratory outcomes. Pseudoglandular PM2.5 exposure modestly increased risk of current asthma (RRadj = 1.15, 95% CI: 0.88-1.51); canalicular PM2.5 exposure modestly increased risk of asthma with recent exacerbation (RRadj = 1.26, 95% CI: 0.86-1.86) and persistent wheezing (ORadj = 1.28, 95% CI: 0.86-1.89). Similar findings were observed for O3, but not NO2, and associations were strengthened among mothers without asthma. While not statistically distinguishable from the null, trends in effect estimates suggest some adverse associations of early pregnancy air pollution exposures with child respiratory conditions, warranting confirmation in larger samples.

U-shaped relationship between ozone exposure and preterm birth risk associated with preconception telomere length

There are conflicting findings regarding the association of ozone (O3) exposure with preterm birth (PTB) occurrence. In the present study, two cohorts were combined to explore the relationship between maternal O3 exposure during pregnancy and PTB risk, and analyze the underlying mechanisms of this relationship in terms of alterations in the preconception telomere length. Cohort 1 included mothers who participated in the National Free Preconception Health Examination Project in Henan Province from 2014 to 2018 along with their newborns (n = 1,066,696). Cohort 2 comprised mothers who conceived between 2016 and 2018 and their newborns (n = 1871) from six areas in Henan Province. The telomere length was assessed in the peripheral blood of mothers at the preconception stage. Data on air pollutant concentrations were collected from environmental monitoring stations and individual exposures were assessed using an inverse distance-weighted model. O3 concentrations (100.60 ± 14.13 μg/m3) were lower in Cohort 1 than in Cohort 2 (114.09 ± 15.17 μg/m3). Linear analyses showed that PTB risk decreased with increasing O3 exposure concentrations in Cohort 1 but increased with increasing O3 exposure concentrations in Cohort 2. Nonlinear analyses revealed that PTB risk tended to decrease and then increase with increasing O3 exposure concentrations in both cohorts. Besides, PTB risk was reduced by 88% for each-unit increase in telomere length in those exposed to moderate O3 concentrations (92.4-123.7 μg/m3, P < 0.05). While no significant association was observed between telomere length and PTB at extreme O3 concentration exposure during entire pregnancy (<92.4 or >123.7 μg/m3, P > 0.05) in Cohort 2. These findings reveal a nonlinear (U-shaped) relationship between O3 exposure and PTB risk. Furthermore, telomere with elevated length was associated with decreased risk of PTB only when exposed to moderate concentrations of O3, but not when exposed to extreme concentrations of O3 during pregnancy.

Preconceptional, pregnant, and postnatal exposure to outdoor air pollution and indoor environmental factors: Effects on childhood parasitic infections

BACKGROUND

Parasitic infections (PIs) are common and pose substantial health hazards in children globally, but the fundamental environmental variables exposure during crucial time window(s) are unclear.

OBJECTIVES

To identify key indoor and outdoor environmental factors leading to childhood PIs throughout critical time window(s).

METHODS

A combined cross-sectional and retrospective cohort study was performed on 8689 children residing in Changsha, China. Data was acquired pertaining to the health status and environmental exposure of the children in their homes. Personal exposure to outdoor air pollutants at the residential address during the preconceptional, perinatal, and postnatal periods was computed using data from ten air quality monitoring stations. An analysis of the relationships between childhood PIs and both indoor and outdoor factors was conducted using a multiple logistic regression model.

RESULTS

Childhood PIs were associated with outdoor CO and ozone (O3) exposure during the 10th-12th months prior to pregnancy, with ORs (95 % CI) of 1.68 (1.24-2.27) and 1.60 (1.15-2.22), respectively; childhood PIs were also associated with CO exposure during one year prior to pregnancy and the first trimester in utero [ORs = 1.57 (1.14-2.15) and 1.52 (1.17-1.97)]. Childhood PIs were found to be associated with PM2.5 exposure during pregnancy and the first year, with odds ratios of 1.51 (1.14-2.00) and 1.95 (1.22-3.12) per IQR increase in pollutant exposure, respectively. Exposures to smoke, renovation-related indoor air pollution (IAP), dampness and plant-related indoor allergens in the early life and past year were all associated with childhood PI, with odds ratios (95 % CI) ranging from 1.40 (1.01-1.95) for environmental tobacco smoke (ETS) during pregnancy to 1.63 (1.12-2.37) for mold/damp stains in the past year. In terms of PI risk, the early life and present periods were critical time windows for outdoor and indoor exposures, respectively. Certain individuals were more vulnerable to the PI risk associated with both indoor and outdoor exposures. Antibiotic use during child's lifetime and early years increased and decreased the PI risk of exposure to outdoor and indoor environments, respectively.

CONCLUSIONS

Exposure to outdoor air pollution in early life and indoor environments in the past year were found to be associated with childhood PI.

Early-life cadmium exposure elevates susceptibility to allergic asthma in ovalbumin-sensitized and challenged mice

Increasing evidence have demonstrated that early-life exposure to environmental toxicants elevates risk of allergic asthma. Cadmium (Cd) is widely present in the environment. The purposes of this study were to evaluate the impact of early-life Cd exposure on susceptibility to ovalbumin (OVA)-evoked allergic asthma. Newly weaned mice were subjected to a low concentration of CdCl₂ (1 mg/L) by drinking water for 5 consecutive weeks. Penh value, an index of airway obstruction, was increased in OVA-stimulated and challenged pups. Abundant inflammatory cells were observed in the lung of OVA-exposed pups. Goblet cell hyperplasia and mucus secretion were shown in the airway of OVA-stimulated and challenged pups. Early-life Cd exposure exacerbated OVA-evoked airway hyperreactivity, Goblet cell hyperplasia and mucus secretion. The in vitro experiments showed that mucoprotein gene MUC5AC mRNA was upregulated in Cd-exposed bronchial epithelial cells. Mechanistically, endoplasmic reticulum (ER) stress-related molecules GRP78, p-eIF2α, CHOP, p-IRE1α and spliced XBP-1 (sXBP-1) were elevated in Cd-subjected bronchial epithelial cells. The blockade of ER stress, using chemical inhibitor 4-PBA or sXBP-1 siRNA interference, attenuated Cd-induced MUC5AC upregulation in bronchial epithelial cells. These results indicate that early-life Cd exposure aggravates OVA-induced allergic asthma partially through inducing ER stress in bronchial epithelial cells.

Air Pollution: Possible Interaction between the Immune and Nervous System?

Exposure to environmental pollutants is a serious and common public health concern associated with growing morbidity and mortality worldwide, as well as economic burden. In recent years, the toxic effects associated with air pollution have been intensively studied, with a particular focus on the lung and cardiovascular system, mainly associated with particulate matter exposure. However, epidemiological and mechanistic studies suggest that air pollution can also influence skin integrity and may have a significant adverse impact on the immune and nervous system. Air pollution exposure already starts in utero before birth, potentially causing delayed chronic diseases arising later in life. There are, indeed, time windows during the life of individuals who are more susceptible to air pollution exposure, which may result in more severe outcomes. In this review paper, we provide an overview of findings that have established the effects of air pollutants on the immune and nervous system, and speculate on the possible interaction between them, based on mechanistic data.

Effect of maternal ozone exposure before and during pregnancy on wheezing risk in offspring: A birth cohort study in Guangzhou, China

Ozone (O₃) exposure may lead to the development and exacerbation of asthma or wheezing in postnatal children; however, it has rarely been studied before and during pregnancy. Wheezing is one of the most common symptoms when diagnosing of asthma; thus, we investigated the associations of O₃ exposure before and during pregnancy with wheezing in preschool children and the potential susceptible exposure windows from a heavily polluted city in China. This population-based birth cohort study, which included 3725 mother-child pairs from Guangzhou, began in 2016, and the follow-up period ended on July 31, 2020. We used a spatiotemporal land-use-regression model combined with activity patterns to estimate the daily O₃ exposure levels during the pre-pregnancy period and each trimester, and wheezing was recorded by reviewing medical records. We used the Cox proportional hazard model to quantify the effects of O₃ exposure on childhood wheezing adjusted for potential confounders. No significant association was detected between pre-pregnancy exposure to O₃ and childhood wheezing. However, increased ambient O₃ exposures throughout pregnancy and in the second trimester were positively associated with the risk of childhood wheezing, with hazard ratios (HRs) and 95% confident intervals (CIs) per interquartile range (IQR) increment of 1.22 (95% CI: 1.04-1.44) and 1.31 (95% CI: 1.09-1.58), respectively. The effects of maternal O₃ exposure on childhood wheezing risk was stronger when the exposure occurred in the warm conception season (P < 0.05). Significant childhood wheezing risk could be attributable to maternal O₃ exposure, especially during the second trimester and with warm-season conception in Guangzhou. Further cohorts of children, particularly school age children who have more robust asthma diagnoses, should be investigated in the future.

Prenatal low-dose antibiotic exposure and children allergic diseases at 4 years of age: A prospective birth cohort study

BACKGROUND

Based on a medical record or questionnaire survey approach, previous epidemiological studies have investigated associations between maternal antibiotic exposure during pregnancy and childhood allergic diseases. However, biomonitoring studies on the prenatal low-dose antibiotic exposure, mainly from the environment and contaminated food, and in relation to children allergic diseases, are missing.

OBJECTIVES

This research aimed to examine the associations between prenatal low-dose antibiotic exposure measured at multiple time points and children current allergic diseases at 4 years of age.

METHODS

The current study including 2453 mother-child pairs was based on the Ma'anshan Birth Cohort study. Selected 41 antibiotics and their two metabolites, which including human antibiotics (HAs), preferred as human antibiotics (PHAs), veterinary antibiotics (VAs) and preferred as veterinary antibiotics (PVAs), in urine samples from 2453 pregnant women were biomonitored through liquid chromatography-triple quadrupole tandem mass spectrometry. Information on children current allergic diseases were collected via validated questionnaires. Generalized estimating equation were used to explore the associations between the repeated measurements of maternal urinary antibiotic over three trimesters and current allergic diseases in children.

RESULTS

The detection rates of nine individual antibiotics in the three trimester during pregnancy are greater than 10%, and the 90th percentile concentration of the detected antibiotics ranges from 0.07 to 22.34 µg/g, and the 95th percentile concentration ranges from 0.17 to 59.57 µg/g. Among the participants, each one-unit concentration increment of sulfamethazine (adjusted OR=1.28, 95% CI: 1.10, 1.49, P-_FDR=0.014) in the first trimester and ciprofloxacin (adjusted OR=1.17, 95% CI: 1.07, 1.28, P-_FDR=0.008) in the second trimester were associated with an increased risk of current eczema in children. In the third trimester, each one-unit concentration increment of oxytetracycline (adjusted OR=1.90, 95% CI: 1.30, 2.78, P-_FDR=0.014) was associated with an increased risk of current asthma in children. Gender-stratified analyses demonstrated that no gender differences were observed in the associations between prenatal antibiotic exposure and current allergic diseases in children.

CONCLUSIONS

Maternal exposure to certain specific VAs or PVAs (sulfamethazine, ciprofloxacin and oxytetracycline) in different trimesters was associated with an increased risk of current asthma and current eczema in 4-year-old children. No gender differences were found in these associations. Further studies are warranted to confirm our findings and explore the potential mechanisms.

Effects of intrauterine exposure to concentrated ambient particles on allergic sensitization in juvenile mice

Intrauterine exposure to particulate matter (PM) has been associated with an increased risk of asthma development, which may differ by the age of asthma onset, sex, and pollutant concentration. To investigate the pulmonary effects of in utero exposure to concentrated urban ambient particles (CAPs) in response to house dust mite (HDM) sensitization in juvenile mice. Mice were exposed to CAPs (600 μg/m³ PM_2.5) during the gestational period. Twenty-two-day postnatal mice were sensitized with HDM (100 μg, intranasally, 3 times per week). Airway responsiveness (AHR), serum immunoglobulin, and lung inflammation were assessed after 43 days of the postnatal period. Female (n = 47) and male (n = 43) mice were divided into four groups as follows: (1) FA: not exposed to CAPs; (2) CAPs: exposed to CAPs; (3) HDM: sensitized to HDM; and (4) CAPs+HDM: exposed to CAPs and HDM-sensitized. PM_2.5 exposure did not worsen lung hyperresponsiveness or allergic inflammation in sensitized animals. The levels of the lung cytokines IL-4, TNF-α, and IL-2 were differentially altered in male and female animals. Males presented hyporesponsiveness and increased lung macrophagic inflammation. There were no epigenetic changes in the IL-4 gene. In conclusion, intrauterine exposure ambient PM_2.5 did not worsened allergic pulmonary susceptibility but affected the pulmonary immune profile and lung function, which differed by sex.

Exposure to O3 during pregnancy and offspring asthma induced by OVA: Sensitive window identification

BACKGROUND

Evidence proved that gestational ozone (O₃) exposure can increase the risk of neonatal adverse respiratory outcomes, but offspring asthma is unclear.

OBJECTIVE

This study aimed to investigate whether gestational O₃ exposure could exacerbate offspring asthma, and to research the differences in effects of O₃ exposure at different gestational periods on offspring asthma.

METHODS

The pregnant ICR mice were randomly grouped and were administered O₃ (air as control) at gestational day (GD) 1-6, 7-12, and 13-18, respectively. The pups aged 2-4 weeks were treated with ovalbumin (OVA) to establish a model of early life asthma. Asthma characteristics such as pulmonary inflammation, goblet cell proliferation, airway remodeling, OVA-specific immunoglobulin (Ig) E secretion and cytokines were examined.

RESULTS

OVA sensitization and challenge successfully induced asthma in offspring. Compared with the air control, pulmonary inflammation infiltration, mucous secretion, the concentration of OVA-specific IgE, the level of tumor necrosis factor (TNF)-α, and T helper (Th) 2-skewed response were significantly exacerbated when O₃ exposure at GD13-18 following inhaling OVA, while pulmonary inflammatory infiltration, mucus secretion, and Th2-skewed response were not significantly changed when O₃ exposure at both GD1-6 and GD7-12. What's more, the above indicators in asthmatic offspring due to O₃ exposure at GD13-18 were more severe than at GD1-6 and GD7-12. Interestingly, the signs of asthma only appeared in the offspring after OVA inhalation. When offspring were not treated with OVA, the prenatal O₃ exposure alone did not lead to asthmatic reactions in offspring. In addition, O₃ exposure at GD13-18 markedly increased the number of neutrophils and macrophages in Bronchoalveolar Lavage Fluid (BALF) of asthmatic offspring, and significantly exacerbated Th2 immune imbalance in asthmatic offspring, but had no effect on Th17 immune imbalance.

CONCLUSION

Exposure to O₃ during pregnancy aggravated asthma in offspring, in which the third trimester is the most sensitive window.