CYP1A1/1B1 and CYP2A6/2A13 activity is conserved in cultures of differentiated primary human tracheobronchial epithelial cells

BackgroundThe respiratory tract is the primary route of exposure to inhaled toxicants such as environmental pollutants and tobacco smoke. Metabolic activation of xenobiotics is a contributor to the onset of lung diseases. Enzymes such as CYP1A1/1B1 and CYP2A6/2A13 activate polycyclic aromatic hydrocarbons and nitrosamines, respectively. Yet, few in vitro models retaining both adequate morphology and metabolic activities are currently available to investigate smoke toxicity.ObjectiveWe characterised the expression and activity of the toxicologically relevant metabolic enzymes CYP1A1/1B1 and CYP2A6/2A13 in polarised primary tracheobronchial epithelial cells cultured at the air–liquid interface. Metabolic activity was compared with NCI-H292 and A549, two commonly used lung epithelial cell models.ResultsWe report that CYP activity and inducibility is conserved in polarised primary tracheobronchial epithelial cells for 7- and 28-days cultured at the air–liquid interface. In comparison, NCI-H292 cells did not show CYP2A6/2A13 activity whilst A549 cells did not display significant metabolic activity for CYP1A1/1B1 or CYP2A6/2A13.ConclusionPrimary tracheobronchial epithelial cells retain both a polarised morphology and significant metabolic activity over a prolonged period of time. On the other hand, although A549 cells and NCI-H292 cells have been extensively used as lung models for toxicological assessment, they lack critical metabolic activation capability.

► NHTBE cells are primary human tracheobronchial cells.
► NHTBEs are a potential model to study bioactivation of inhaled toxicants in vitro.
► We confirmed that NHTBEs cells form a polarised epithelium when grown in vitro.
► Activity of P450s involved in bioactivation was detected in 7 and 28 days cultures.
► In comparison, metabolism was limited in respiratory tract cell lines (A549, H292).