Predicting Respiratory Toxicity Using a Human 3D Airway (EpiAirway™) Model Combined with Multiple Parametric Analysis

The objective of this study was to assess the potential for an in vitro three-dimensional human airway model (Epi-AirwayTM) to accurately predict respiratory toxicity in humans. This was done by exposing EpiAirway tissues to known respiratory toxicants and assessing tissue viability (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide [MTT] assay and histology), oxidative stress of the tissues (cellular glutathione [GSH] levels), and gene expression of classical markers for inflammation, metabolic activity, and apoptosis by quantitative real-time re-verse transcription–polymerase chain reaction (qRT-PCR). These findings were then compared with reported human in vivo results to assess the predictive capabilities. The compounds assessed were bleomycin, cadmium chloride, lipopolysaccharide, silica, beryllium sulfate, and doxorubicin. The apical surfaces of EpiAirway tissues were exposed to test compounds over a broad range of exposure concentrations for 24 or 72 hours. Only two com-pounds exhibited reduced cell viability relative to controls via MTT: cadmium chloride (57% viable at 24 hours) and doxorubicin (57% viable at 72 hours). However, histological analysis showed that cadmium chloride, doxo-rubicin, and bleomycin induced significant structural breakdown and cell loss after 24 hours of exposure, which was not reflected in theMTTassay. Total intracellular GSH levels were 45–80% of control after 24 hours with all compounds tested with the exception of cadmium chloride, which showed no reduction of cellular GSH. The qRT-PCR results showed strikingly similar results to known in vivo responses for all test materials assessed. These re-sults suggest that the MatTek EpiAirway model can not only provide an accurate assessment of acute respiratory toxicity but also predict the in vivo responses of respiratory toxins in humans.

EpiAirway, AIR-100, respiratory toxicity, AIR-196, histology, oxidative stress, glutathione levels, gene expression, inflammation, metabolic activity, apoptosis, qRT-PCR,  LDH, TNF-a, TGF-b, IL-1a, IL-6, IL-8, CYP1A1 , Bax, Bcl2

Bleomycin, cadmium chloride, lipopolysaccharide, silica, beryllium sulfate, doxorubicin