Comparison of 3D airway models for the assessment of fibrogenic chemicals

Lung epithelial cells and fibroblasts play key roles in pulmonary fibrosis and are involved in fibrotic signaling and production of the extracellular matrix (ECM), respectively. Recently, 3D airway models consisting of both cell types have been developed to evaluate the fibrotic responses while facilitating cell–cell crosstalk. This study aimed to evaluate the fibrotic responses in these models using different fibrogenic agents, which are known as key events in adverse outcome pathways of pulmonary fibrosis. We quantified cell injury and several sequential steps in fibrogenesis, including inflammation, the epithelial–mesenchymal transition (EMT), fibroblast activation, and ECM accumulation, using two different 3D airway models, the EpiAirwayTM-full thickness (Epi/FT) and MucilAirTM-human fibroblast (Mucil/HF) models. In the Epi/FT model, fibrogenic agents induced the expression of inflammation and EMT-associated markers, while in the Mucil/HF model, they induced fibroblast activation and ECM accumulation. Using this information, we conducted gene ontology term network analysis. In the Epi/ FT model, the terms associated with cell migration and response to stimulus made up a large part of the network. In the Mucil/HF model, the terms associated with ECM organization and cell differentiation and proliferation constituted a great part of the network. Collectively, our data suggest that polyhexamethyleneguanidine phosphate and bleomycin induce different responses in the two 3D airway models. While Epi/FT was associated with inflammatory/EMT-associated responses, Mucil/HF was associated with fibroblast-associated responses. This study will provide an important basis for selecting proper 3D airway models and fibrogenic agents to further research or screen chemicals causing inhalation toxicity.

Epithelium-fibroblasts crosstalk, Lung fibrosis, Polyhexamethyleneguanidine, Bleomycin, nucleotide binding oligomerization domain-like receptor family pyrin domain-containing-3 (NLRP3), epithelial–mesenchymal transition (EMT) markers, E-cadherin, N-cadherin, alpha-smooth muscle actin, a-SMA, fibroblast activation markers, collagen I, fibronectin, connective tissue growth factor (CTGF), plasminogen activator inhibitor-1 (PAI-1), inflammation markers, TNF-α, IL-1β, IL-6, IL-8, fibroblast activation PAI-1, PDGF, FGF-2, MMP-1, MMP-2, MMP-9, TIMP-1, TIMP-2, pulmonary fibrosis

Polyhexamethyleneguanidine, Bleomycin