PROJECT SUMMARY Asthma affects approximately 10% of US children and is a leading cause of respiratory morbidity and hospitalization. Asthma disproportionally affects parent-identified Black and Caribbean Hispanic children, and the large and diverse population of the Environmental Influences on Child Health Outcomes (ECHO) study is ideal for identifying early-life causes for asthma disparities. The Wisconsin Infant Study Cohort (WISC) is a birth cohort of underserved rural families and children. This population would bring unique data to ECHO related to exposures (animals, microbiome), neighborhood factors (low population density, clean air), and health outcomes (reduced rates of respiratory diseases). Our scientific goals focus on how environmental factors and hormonal influences in adolescence regulate molecular responses of nasal airway cells (NAC). We will analyze DNA methylation (DNAm) and gene expression from NAC samples in mid-childhood and early adolescence and combine these data to identify “molecular phenotypes.” We hypothesize that these phenotypes relate to specific environmental exposures in early life and asthma-related outcomes at ages 6-10 and during a three year follow- up period. We therefore propose the following specific aims: Aim 1. To leverage ECHO Protocol 3.0 core data, we will analyze NAC gene expression and DNAm in children ages 6-10 years to identify airway cell molecular phenotypes and then test for associations with prenatal and early postnatal environmental exposures, personal factors (sex, parent-identified race/ethnicity, age, polymorphisms of candidate genes), and clinical outcomes (asthma, rhinitis, lung function). Aim 2. We will reassess asthma outcomes and nasal airway cells three years later (ages 9-13 years) to determine how asthma disease activity and changes in severity relate to: a) the molecular phenotypes at 6-10 years, b) potential asthma modifying factors such as sex hormones, insulin resistance, and allergy, and c) changes in DNAm and gene expression. Aim 3. We propose to update and adapt existing WISC protocols and adopt new ECHO systems to maximize retention of existing participants, contribute diversity related to rural and farming exposures and lifestyles, and implement the ECHO Cohort Protocol with high fidelity. These proposed studies will link modifiable environmental exposures to molecular regulation of airway cells and allergy and asthma clinical outcomes. The results will yield a treasure trove of information that could inform new strategies to prevent asthma and, in affected children, enable innovative approaches to promote disease control and remission.