Wildfire Smoke-Induced Transcriptomic Changes in the Mouse Lung and Heart

These analyses set out to evaluate transcriptomic responses in the mouse lung and heart in response to simulated wildland fire exposure conditions. These exposure conditions were based on smoke condensate consisting of particulate matter and semivolative organic compounds resulting from the burning of five biomass fuels; namely eucalyptus, pine, pine needles, peat, and red oak. These biomasses were evaluated under two burn conditions: flaming and smoldering. Biological responses resulting from these exposures have been previously evaluated using an in vivo model (CD-1 mice) and an Ames mutagenicity assay (Kim et al. 2018, PMID: 29373863). For the in vivo evaluation, female mice were exposed to biomass smoke condensate samples using 50 uL saline containing 2 mg/mL PM administered to the lungs by oropharyngeal aspiration. Samples were collected at 4 and 24 h post-exposure. Mouse lung toxicity response data included alterations in immune cell populations, including neutrophil and macrophage counts, as well as protein markers of inflammation and tissue damage. The in vivo toxicity responses associated with each biomass burn condition were evaluated on the basis of equal mass as well as emission factors derived from the amount of biomass fuel consumed. Here, we expanded upon this important study by integrating toxicity responses, including newly generated transcriptional signatures, with chemical profiles to further characterize systems-level toxicity associated with wildfire smoke and provide much-needed understanding towards which components of wildfire smoke are the most harmful.