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Growth of human bronchial epithelial cells at an air-liquid interface alters the response to particle exposure
Citation:
Ghio, Andy, L. Dailey, J. Soukup, J. Stonehuerner, J. Richards, L. Brighton, A. Ross, AND R. Devlin. Growth of human bronchial epithelial cells at an air-liquid interface alters the response to particle exposure. Particle and Fibre Toxicology. BioMed Central Ltd, London, Uk, 10(1):25, (2013).
Impact/Purpose:
Epithelial cells grown at an air-liquid interface exhibit an altered response to particle exposures that may be dependent upon oxygen levels, iron homeostasis or a combination of the two. This research adds insights into in vitro characterization of particle injury.
Description:
Abstract: We tested the hypothesis that relative to submerged cells, airway epithelial cells grown at an air-liquid interface would have an altered response to particle exposure. RNA for IL-8, IL-6, heme oxygenase 1 and cyclooxygenase 2 increased following exposure of submerged airway epithelial cells to ambient air pollution particle. The same cells allowed to differentiate over 21 days at an air-liquid interface demonstrated no such changes following particle exposure. Comparable to the NHBE cells exposed to Chapel Hill PM, BEAS-2B cells grown at an air-liquid interface demonstrated a significant decrease in IL-8 and HOX1 RNA after exposure to NIST 1648 particle relative to the same cells exposed during submersion in media. An effect of differentiation of NHBE cells grown at an air-liquid interface on baseline levels of RNA for these same proteins (i.e. IL-8, IL-6, HOX1, and COX2) demonstrated significantly changes during differentiation of NHBE cells at an air-liquid interface over 3 to 21 days with no exposure to particles. BEAS-2B cells grown at an air liquid interface showed comparable changes in RNA for IL-8 and HOX1 between 3 and 21 days of growth. Subsequently, it is not possible to attribute the observed decreases in PM response of respiratory epithelial cells to differentiation alone since BEAS-2B cells, which do not differentiate, showed a similar pattern to that of NHBE cells. NHBE and BEAS-2B cells grown on a transwell in 95% N2/5%CO2 and exposed to NIST 1648 particle demonstrated significantly greater changes in IL-8 and HOX1 relative to the cells grown in 95% air/5% CO2 after particle exposure. We conclude that growth of airway epithelial cells at an air-liquid interface is associated with a diminished biological effect following particle exposure. This decreased response was not related to differentiation but corresponded to changes in oxygen availability.