Dose-Dependent Respiratory and Proinflammatory Gene Impacts of Acrolein in Mice and Validation of In Vitro Effects

In vitro approaches to risk assessment of hazardous air pollutants (HAPs) include dose-response relationships of cytotoxicity, cell membrane integrity, and changes in gene expression. Comparison of these responses with in vivo models will assist in validating these approaches and better informing risk assessment of HAPs and other air pollutants. In this study we assessed physiological responses and respiratory tract gene changes in adult Balb/cJ mice exposed acutely by nose-only inhalation to acrolein or clean air (n=8/group). Real-time pulmonary responses were measured using head-out plethysmography (emka Technologies) in which mice were exposed to clean air for 20 min prior to acrolein to provide control pulmonary function values. During 4 hours continuous exposure to acrolein (0.32, 1.0, or 3.2 ppm), concentration-dependent reductions in breathing frequency (73, 65, or 36% of air baseline, respectively) and minute volume (71, 67, or 46% of baseline, respectively) were observed (p < 0.05 for all). Within 2 hours post-exposure, respiratory tract tissues (lateral and septal nasal epithelium and lung) were taken for evaluation of dose-related gene changes relevant to inflammation, cytotoxicity, and other toxicity pathways. Septal nasal epithelium samples (minimum 400 ng RNA) were run on a NanoString nCounter mouse inflammation marker gene panel. The nasal epithelium samples (minimum 100 ng RNA) are also analyzed on BioSpyder targeted RNA-Seq (TempO-seq) for direct comparison to benchmark dose modeling results from BEAS-2B human lung epithelial cells which were exposed at the air-liquid interface to the same concentrations of acrolein for 2 hours and assessed 4 hours post-exposure. Data from these studies will examine the degree of correlation between inflammatory gene changes from the in vivo and in vitro approaches to determine the utility of the in vitro methodologies for risk assessment of HAPs. (This abstract does not represent U.S. EPA policy.)

Impact/Purpose

Comparison of in vitro responses with in vivo models will assist in validating in vitro approaches and better informing risk assessment of hazardous air pollutants. This study assessed physiological responses and respiratory tract gene changes in mice exposed acutely by nose-only inhalation to acrolein, and measured real-time pulmonary responses and gene changes in the respiratory tract. Acrolein induced-dose-dependent reductions in respiratory function and changes in nasal epithelial inflammatory markers which can be compared with responses in cells exposed to similar concentrations in vitro. Further correlation assessments are needed for other HAPs to determine the utility of the in vitro methodologies for risk assessment.

Citation

Gavett, S., S. Vance, R. Fannin, A. Fisher, P. Evansky, A. Speen, M. Higuchi, AND Ian Gilmour. Dose-Dependent Respiratory and Proinflammatory Gene Impacts of Acrolein in Mice and Validation of In Vitro Effects. Society of Toxicology, San Diego, California, March 27 - 31, 2022.