Evaluating Short- and Long-Term Toxicity Response of Models Comprising Fully Differentiated Primary Bronchial Tracheal Epithelial Cells to Either Cadmium Chloride or Pentamidine

Respiratory tract diseases stemming from toxic compound exposure significantly contribute to the global health burden. Traditional in vitro airway models, due to their lack of physiological relevance, are often unable to provide meaningful and accurate toxicological assessments. Advanced in vitro airway models, however, promise to provide more predictive information for use in human airway health. Here, we constructed mature airway models comprising fully differentiated primary bronchial tracheal epithelial cells incubated in 24-well plate inserts and cultured under air-liquid interface for 4 weeks. The toxicological response to short-term (24 hours) exposure to either cadmium chloride (CdCl₂) or pentamidine were evaluated and compared in both differentiated and undifferentiated cells. The toxicological response to long-term exposure (1, 2 weeks) to either compound in differentiated airway models was also explored. Changes in viability and cytokine expression was quantified and compared in both models. Additionally, histological imaging (H&E, alcian blue, IHC) was conducted on mature airway models to visually assess model disruption, inflammation, and tight junction disruption. We observed that all airway models expressed dose-dependent response to both CdCl₂ and pentamidine exposure, with increased cell death corresponding with increased compound concentrations. Additionally, differentiated models demonstrated higher resistivity to cell death compared to undifferentiated counterparts. Moreover, exposure to low concentrations of the compound resulted in increased cytokine expression relative to untreated controls. Finally, long-term exposure to CdCl₂ resulted in model disruption and death, whereas pentamidine exposure demonstrated limited model disruption. These results suggest that these airway models may serve as useful tools future airway toxicity research.