Recent advancements and application of in vitro models for predicting inhalation toxicity in humans

Twenty-eight day repeated exposure of human 3D bronchial epithelial model to heated tobacco aerosols indicates decreased toxicological responses compared to cigarette smoke

“…Furthermore, the substantially reduced toxicological responses of NGPs compared to combustible cigarette has been demonstrated in a number of in vitro studies, in both 2D and 3D cell models ( Iskandar et al, 2018 ; Czekala et al, 2019 ; Czekala et al, 2020; Haswell et al, 2021 ; Simms et al, 2021 ; Simms et al, 2022 ). Three dimensional (human) lung cell models are a useful tool in the assessment of the effects of inhalable test articles such as combustible cigarette smoke or NGP aerosols ( Bedford et al, 2022 ). These models offer a human-relevant cellular system, grown and/or stimulated under air-liquid interface (ALI) conditions, and can include a variety of relevant cell types (e.g., basal, goblet and ciliated cells); this is more closely representative of an in vivo scenario than using single cell-type 2D cultures, for example ( Huang et al, 2013 ; Cervena et al, 2019 ).…”

“…This, coupled with the application of whole aerosol/smoke exposures at the ALI can model exposure of cells to as representative a chemical mixture to that which the consumer would be exposed to as possible ( Chapman et al, 2023 ). In vitro 3D models exposed to whole NGP aerosol or combustible cigarette smoke have been used to assess a number of endpoints associated with the development and progression of respiratory diseases, including functional and morphological changes like cilia activity and ratios of cell types (e.g., goblet cells, ciliated cells), inflammatory readouts and genomic level changes ( Czekala et al, 2019 ; Rayner et al, 2019 ; Ghosh et al, 2020 ; Haswell et al, 2021 ; Bedford et al, 2022 ).…”

“…As part of this pathway, FoxJ1 has a role in ciliogenesis, and its decreased expression, which has been linked with combustible cigarette smoke exposure, is associated with loss/absence of cilia ( Luettich et al, 2021 ). Goblet cell hyperplasia is another process associated with respiratory disease pathologies, and has recently been modelled in vitro during sub-cytotoxic repeated exposures to diluted combustible cigarette smoke (but was not induced by HTP aerosol exposure) ( Haswell et al, 2021 ); Muc5AC is often used as a marker for mucin gene expression ( Behrsing et al, 2016 ; Bedford et al, 2022 ). Additionally, changes in inflammatory markers are used as a proxy of inflammatory responses in vitro , and a number of mediators, including the cytokines, TNFα and interleukins (ILs), and matrix metalloproteinases (MMPs), are associated with exposure to inhaled toxicants, including combustible cigarette smoke ( Behrsing et al, 2016 ; Czekala et al, 2021 ; Bedford et al, 2022 ; Langel et al, 2022 ).…”

“…Goblet cell hyperplasia is another process associated with respiratory disease pathologies, and has recently been modelled in vitro during sub-cytotoxic repeated exposures to diluted combustible cigarette smoke (but was not induced by HTP aerosol exposure) ( Haswell et al, 2021 ); Muc5AC is often used as a marker for mucin gene expression ( Behrsing et al, 2016 ; Bedford et al, 2022 ). Additionally, changes in inflammatory markers are used as a proxy of inflammatory responses in vitro , and a number of mediators, including the cytokines, TNFα and interleukins (ILs), and matrix metalloproteinases (MMPs), are associated with exposure to inhaled toxicants, including combustible cigarette smoke ( Behrsing et al, 2016 ; Czekala et al, 2021 ; Bedford et al, 2022 ; Langel et al, 2022 ). It is for the above reasons that these cellular processes (cilia activity (beat frequency and active area), FoxJ1 expression, changes in goblet cells, inflammatory readouts) are often used as in vitro indicators of potential responses to inhaled test articles ( Behrsing et al, 2016 ; Iskandar et al, 2017 ; Czekala et al, 2021 ; Bedford et al, 2022 ).…”

“…Additionally, changes in inflammatory markers are used as a proxy of inflammatory responses in vitro , and a number of mediators, including the cytokines, TNFα and interleukins (ILs), and matrix metalloproteinases (MMPs), are associated with exposure to inhaled toxicants, including combustible cigarette smoke ( Behrsing et al, 2016 ; Czekala et al, 2021 ; Bedford et al, 2022 ; Langel et al, 2022 ). It is for the above reasons that these cellular processes (cilia activity (beat frequency and active area), FoxJ1 expression, changes in goblet cells, inflammatory readouts) are often used as in vitro indicators of potential responses to inhaled test articles ( Behrsing et al, 2016 ; Iskandar et al, 2017 ; Czekala et al, 2021 ; Bedford et al, 2022 ). Therefore in the current study, we looked to assess these endpoints.…”