Air Pollution and Effects on Lung Functional Development and Respiratory Morbidity in At-Risk Infants

BACKGROUND AND RATIONALE: This is a direct continuation of SNF 182871/1, which investigated the impact of early-childhood environmental factors on lung functional growth and consequences for later respiratory morbidity in healthy term infants. We previously demonstrated that even low-level air pollution exposure during pregnancy and early childhood is associated with impaired lung functional growth in infancy and early childhood. Although the mechanisms are still unclear, they could be related to lung functional growth deficits or remodeling of the lung due to changes in the intrauterine environment. Air pollution is known to induce oxidative stress response and related autophagy and cellular senescence mechanisms, potentially playing a role in pollution-related lung pathology and in remodeling. As novel preliminary evidence in SNF 182871/1, we recently found that, in the cord blood of human infants, autophagy-related biomarkers are correlated with remodeling biomarkers. We also found that air pollution exposure during pregnancy is associated with biomarkers of autophagy and remodeling in the cord blood of healthy term infants. Interestingly, these mechanisms also play an important role in fetal development and preterm birth, and may thus theoretically contribute to the susceptibility of infants-and particularly preterm infants-to oxidative stress and air pollution effects. Indeed, as first evidence from SNF 182871/1, we also found an enhanced impact of air pollutants on lung function impairment of preterm infants. Furthermore, our own preliminary human data show that markers of autophagy, and remodeling already have significant differences between the cord blood of preterm infants compared to term infants at birth prior to early postnatal injury. Bringing this together, we hypothesize that the interaction of oxidative stress response, autophagy and remodeling could be a key mechanism involved in the complex host-environment interaction determining lung functional growth and related respiratory morbidity. Moreover, this response could be different in infants at risk for chronic respiratory symptoms, such preterm infants, infants born from asthmatic mothers or infants exposed to high levels of air pollution during pregnancy. OVERALL OBJECTIVES: We aim to expand the ongoing BILD cohort of (i) term infants with two risk subgroups, (ii) infants born preterm, and (iii) infants born to asthmatic mothers, and we will investigate the differences in response to prenatal air pollution in relation to the above key mechanisms. SPECIFIC AIMS: In comparison to healthy term infants, we will investigate in study phase 1, (i) whether the increased susceptibility of infants to prenatal air pollution in these three risk groups is related to differences in markers of oxidative stress response, autophagy, and remodeling in cord blood and in study phase 2, (ii) whether these pollution-related cord blood profiles are correlated to lung functional development and subsequent symptoms in the first year of life (primary outcomes) and at school age (secondary outcomes). We will replicate these findings in other birth cohorts from collaborators (Germany, Australia) with comparable outcome measures. METHODS: In our prospective BILD birth cohort of 1000 unselected healthy term infants, 400 preterm infants, and 200 infants from asthmatic mothers we will (i) estimate indoor and outdoor air pollution exposure during pregnancy and in early infancy, (ii) assess family, obstetric and birth history, cord-molecular biomarkers (metabolomics, gene expression, proteins), and infant lung function shortly after birth (including exhalomics) and at 6 years of age, as well as respiratory symptoms in the first year of life and at school age. EXPECTED RESULTS AND IMPACT: We expect a 26.03.2021 18:35:26 Page - 14 - significant correlation between air pollution exposure and oxidative stress response and lung remodeling in newborns with effects on lung function and clinical outcomes, the latter effects enhanced in the risk groups. Particularly for these risk groups, today's air pollution may already result in lung remodeling and subsequent impaired lung functional growth even at this early stage of life. Since early-life lung functional impairment often persists until school age and even late adulthood, it is a previously described early-life risk factor known to be associated with asthma in children and chronic obstructive respiratory airway diseases in the elderly. Thus, early-life environmental injury has a potentially very relevant impact on future global respiratory health, with unpredictable costs. We are one of the first groups to look into the impact of these air-pollution-induced mechanisms on oxidative stress response and lung remodeling, subsequent impairment of lung functional growth, and resulting human lung disease. Better understanding of these mechanisms might help the development of preventative and therapeutic strategies, particularly for at-risk infants.