Project Summary (2022-2027)

This project is aimed at developing novel tools to rapidly characterize pediatric respiratory health risks from exposure to hazardous volatile organic compounds (VOCs). This work is a critical element in the overall strategy of the Texas A&M University Superfund Research Center to characterize and manage the human health risks associated with exposure to environmental emergency-mobilized hazardous substances. Current toxicity testing strategies do not account for developmental stage that is representative of the pediatric lung or encompass human population variability, even though these factors (i.e., age, sex, race, and genetics) are critical in asthma risk. Moreover, mechanisms of action underlying individual/combined VOCs on asthma pathogenesis is poorly understood. To support the evaluation of hazardous VOCs, including real urban mixtures, and elucidate mechanistic linkages, this project tests the hypothesis that the pediatric airway is distinctly susceptible to pulmonary injury from hazardous VOCs, and that airway responses are modulated by extracellular vesicle (EV)-mediated signaling.

The research team brings together a toxicologist, a physician-scientist and an atmospheric chemist to address the following specific aims. Aim 1 prioritizes the evaluation of 20 individual Superfund-priority VOCs to test for asthma-related phenotypes in vitro, first using a respiratory epithelial cell line (16HBE) cultured at air-liquid interface, and then in a population-based, age-appropriate model comprised of pediatric bronchial epithelial cells from the Developing Lung Molecular Atlas Program. Next, representative designed mixtures matching environmentally relevant proportions of chemicals in ambient air are evaluated in the standard and population-based pediatric cell lines. These responses inform Aim 2 mechanistic studies, which test the hypothesis that VOC exposures alter EV protein expression, underlying respiratory dysfunction. It is known that inflammation and epithelial barrier function are mediated by exosomes, a class of secreted EVs ranging from 30 to 150 nm.

In Aim 2, EVs derived from 16HBE cells exposed to select VOCs/mixtures are purified and sequenced using a high-throughput proteomics approach. Protein signatures revealed in this model are then validated across diverse pediatric donor cell lines.

Last, the functional role of VOC-exposed, cell-derived EVs are evaluated using adoptive transfer experiments. In parallel to Aims 1 and 2, Aim 3 objectives characterize VOC mixtures through mobile air monitoring across different locations in the greater Houston Area during baseline and in response to environmental disasters. Additionally, to fill in gaps in disaster-related toxicity testing, 16HBE cells are directly exposed to ambient air onboard the mobile platform in the field, using time-resolved measurements to drive conditional sampling of different air masses. Overall, the novel tools and findings from this project will improve basic understanding of mechanisms underlying VOC-induced pediatric pulmonary injury and enable improved risk assessment to rapidly characterize respiratory hazards that threaten children’s health.