Air pollution from traffic during pregnancy impairs newborn's cord blood immune cells: The NELA cohort

https://doi.org/10.1016/j.envres.2020.110468Get rights and content

Highlights

  • Cord blood NK, cytotoxic T and Treg cells decreased in relation to higher prenatal exposure to traffic-related pollutants.

  • s Higher prenatal exposure to PM10 and PM2.5 was associated with increased total Th and Th1 cells in newborns’ cord blood.

  • Early and late gestation were identified as windows of higher susceptibility of fetal immune system to air pollutants.

  • Our results suggest that prenatal exposure to traffic-related air pollutants impairs fetal immune system development.

Abstract

Background

Hazards of traffic-related air pollution (TRAP) on the developing immune system are poorly understood. We sought to investigate the effects of prenatal exposure to TRAP on cord blood immune cell distributions; and to identify gestational windows of susceptibility.

Methods

In-depth immunophenotyping of cord blood leukocyte and lymphocyte subsets was performed by flow cytometry in 190 newborns embedded in the Nutrition in Early Life and Asthma (NELA) birth cohort (2015–2018). Long-term (whole pregnancy and trimesters) and short-term (15-days before delivery) residential exposures to traffic-related nitrogen dioxide (NO2), particulate matter (PM2.5 and PM10), and ozone (O3) were estimated using dispersion/chemical transport modelling. Associations between TRAP concentrations and cord blood immune cell counts were assessed using multivariate Poisson regression models.

Results

Mean number of natural killer (NK) cells decreased 15% in relation to higher NO2 concentrations (≥36.4 μg/m3) during whole pregnancy (incidence relative risk (IRR), 0.85; 95% CI, 0.72, 0.99), with stronger associations in the first trimester. Higher PM2.5 concentrations (≥13.3 μg/m3) during whole pregnancy associated with a reduced mean number of cytotoxic T cells (IRR, 0.88; 95% CI, 0.78, 0.99). Newborns exposed to higher PM10 (≥23.6 μg/m3) and PM2.5 concentrations during the first and third trimester showed greater mean number of helper T type 1 (Th1) cells (P < 0.05). Decreased number of regulatory T (Treg) cells was associated with greater short-term NO2 (IRR, 0.90; 95% CI, 0.80, 1.01) and PM10 (IRR, 0.88; 95% CI, 0.77, 0.99) concentrations.

Conclusions

Prenatal exposure to TRAP, particularly in early and late gestation, impairs fetal immune system development through disturbances in cord blood leukocyte and lymphocyte distributions.

Section snippets

Funding sources

This study was supported by grants from Instituto de Salud Carlos III, Spanish Ministry of Science, Innovation and Universities, and Fondos FEDER (grant numbers CP14/00046, PIE15/00051, PI16/00422 and ARADyAL network RD160006). AMGS was funded by a predoctoral Fellowship (FI17/00086) and EM was funded by Miguel Servet Fellowships (MS14/00046 and CPII19/00019) awarded by the Instituto de Salud Carlos III, Spanish Ministry of Science, Innovation and Universities, and Fondos FEDER. The funders had

Study participants

Data come from participants embedded in the Nutrition in Early Life and Asthma (NELA) study (www.nela.imib.es), a prospective population-based birth cohort set up in Murcia, a south-eastern Mediterranean region of Spain. The main objective of NELA is to unravel the developmental origins and mechanisms of asthma and allergy.

Pregnant women who fulfill the inclusion criteria were invited to participate in the study at the time of the control ultrasound at 20 weeks of gestation at the

Results

The study population characteristics are presented in Table 1. The mean age of included pregnant women was 33.1 (±4.2) years (mean (±sd)); 52% were primiparous; 57% had a high educational level; and 16% reported to be active smokers during pregnancy. Overall, 23% of women were overweight and 11% obese before pregnancy; 14% reported to be asthmatic and 46% to have a history of atopy. The mean age of fathers was 35.6 (±5.2) years, 35% of them had a high educational level, and 37% reported to be

Discussion

This study shows that residential exposure to higher concentrations of traffic-related air pollutants during pregnancy alters the distribution of cord blood immune cells in neonates and identifies early and late gestation as windows of higher susceptibility. Greater NO2 concentration in early gestation (first trimester) was associated with decreased mean number of leukocytes. The mean number of NK cells decreased in relation to higher levels of NO2 during gestation, with stronger associations

Conclusions

In conclusion, long- and short-term exposure to traffic-related air pollutants through fetal development impairs leukocyte and lymphocyte distributions in cord blood of neonates. Early and late gestation may represent windows of higher susceptibility of fetal immune system to air pollutants. Further research is warranted to unravel whether the potential fetal immunotoxicity of traffic-related air pollutants persists beyond birth and/or leads to adverse immune mediated diseases, including

Credit author statement

Eva Morales and Luis García-Marcos conceived and supervised the project and recruited the participants. Pedro Jiménez-Guerrero and María Muñoz-García provided air pollution data. Carmen Ballesteros-Meseguer and Irene Pérez de los Cobos collected the biological samples. Azahara M. García-Serna, Trinidad Hernández-Caselles, Esther Cantero-Cano, and Elena Martín-Orozco performed the experiments. Azahara M. García-Serna and Trinidad Hernández-Caselles analyzed flow cytometry data. Azahara M.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

The authors particularly thank all the participants for their generous collaboration. We want to particularly acknowledge the BioBank “Biobanco en Red de la Región de Murcia” (PT17/0015/0038) integrated in the Spanish National Biobanks Network (B.000859) for its collaboration.

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      Consequently, we used NO2 concentrations measured by the air quality network background station closest to the mother's address. In the literature, exposure to prenatal TRAP appears to impair fetal immune system development and contribute to the development of childhood wheezing and asthma (García-Serna et al., 2020; Hehua et al., 2017). However, the impact of prenatal TRAP has been studied primarily in young children.

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    1

    Members of the NELA study group listed at the end of the article.

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