Prevalidation of an Acute Inhalation Toxicity Test Using the EpiAirwayIn VitroHuman Airway Model

Abstract

Introduction: Knowledge of acute inhalation toxicity potential is important for establishing safe use of chemicals and consumer products. Inhalation toxicity testing and classification procedures currently accepted within worldwide government regulatory systems rely primarily on tests conducted in animals. The goal of the current work was to develop and prevalidate a nonanimal (in vitro) test for determining acute inhalation toxicity using the EpiAirway™ in vitro human airway model as a potential alternative for currently accepted animal tests.Materials and Methods: The in vitro test method exposes EpiAirway tissues to test chemicals for 3 hours, followed by measurement of tissue viability as the test endpoint. Fifty-nine chemicals covering a broad range of toxicity classes, chemical structures, and physical properties were evaluated. The in vitro toxicity data were utilized to establish a prediction model to classify the chemicals into categories corresponding to the currently accepted Globally Harmonized System (GHS) and the Environmental Protection Agency (EPA) system.Results: The EpiAirway prediction model identified in vivo rat-based GHS Acute Inhalation Toxicity Category 1–2 and EPA Acute Inhalation Toxicity Category I–II chemicals with 100% sensitivity and specificity of 43.1% and 50.0%, for GHS and EPA acute inhalation toxicity systems, respectively. The sensitivity and specificity of the EpiAirway prediction model for identifying GHS specific target organ toxicity-single exposure (STOT-SE) Category 1 human toxicants were 75.0% and 56.5%, respectively. Corrosivity and electrophilic and oxidative reactivity appear to be the predominant mechanisms of toxicity for the most highly toxic chemicals.Conclusions: These results indicate that the EpiAirway test is a promising alternative to the currently accepted animal tests for acute inhalation toxicity.

Spike mutation D614G alters SARS-CoV-2 fitness

“…This airway model contains human tracheal/bronchial epithelial cells in multilayers which resemble the epithelial tissue of the respiratory tract. The primary tissue is cultured at an air-liquid interface to recapitulate the barrier, microciliary response, and infection of human airway tissues in vivo 17,18 . After infecting the airway tissue at an MOI of 5 (as determined on Vero E6 cells), both D614 and G614 viruses produced increasing infectious titers from day 1 to 5, up to 7.8 × 10 5 PFU/ml ( Fig.…”

Invited review: human air-liquid-interface organotypic airway tissue models derived from primary tracheobronchial epithelial cells—overview and perspectives

“…Tissue viability is determined following a 3-h incubation period. This method correlates well with Global Harmonized System (GSH) and EPA acute inhalation toxicity categories determined by in vivo rat inhalation exposures studies and allows for relatively fast screening of large numbers of chemicals (Jackson et al 2018 ). Human ALI airway models have been extensively used to evaluate potential mechanisms of airway toxicity and fibrosis (obliterative bronchiolitis) induced by occupational exposure to artificial butter flavoring chemicals, such as 2,3-butanedione (diacetyl [DA]), including DA-induced basal cell effects (Gwinn et al 2017 ; Foster et al 2017 ; McGraw et al 2020 ) and involvement of EGFR signaling pathway (Kelly et al 2014 ; Foster et al 2017 ; McGraw et al 2020 ).…”

“…Tissue viability is determined following a 3-h incubation period. This method correlates well with Global Harmonized System (GSH) and EPA acute inhalation toxicity categories determined by in vivo rat inhalation exposures studies and allows for relatively fast screening of large numbers of chemicals (Jackson et al 2018 ).…”

“…It is recommended to wash the apical side of the ALI airway cultures with PBS to remove excess mucus secreted by the goblet cells. This is an important practice to ensure homogenous delivery of test articles throughout the culture surface (Jackson et al 2018 ). Dosimetry measurement under such conditions can be made by chemical analysis or using quartz crystal microbalances (QCMs) (Lenz et al 2014 ; Wang et al 2019a ).…”

Discovery and characterization of single-domain antibodies for polymeric Ig receptor-mediated mucosal delivery of biologics

“…The EpiAirway model, engineered from primary human bronchial epithelial cells, is a fully differentiated tissue model that mimics in vivo-like structure and function. 28,29 To measure the transcytosis activity of VHH-mFc molecules, we added 20 μg of VHH-mFc to the basolateral chamber and quantified the amount of VHH-mFc present in the apical mucus at 0, 24 and 48 hours post treatment by electrochemiluminescence method ( Figure S4). Five VHHs (2, 6, 9, 11 and 12) showed >20-fold increase in their mucosal amount relative to control VHH molecules ( Figure 2b).…”