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Growth of human bronchial epithelial cells at an air-liquid interface alters the response to particle exposure.

Ghio AJ, Dailey LA, Soukup JM, Stonehuerner J, Richards JH, Devlin RB - Part Fibre Toxicol (2013)

Bottom Line: Subsequently, it was not possible to attribute the observed decreases in the response of NHBE cells to differentiation alone since BEAS-2B cells, which do not differentiate, showed similar changes when grown at ALI.We conclude that growth of NHBE cells at ALI is associated with a diminished biological effect following particle exposure relative to cells submerged in media.This decreased response showed an association with increased oxygen availability.

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ABSTRACT

Background: We tested the hypothesis that normal human bronchial epithelial (NHBE) cells 1) grown submerged in media and 2) allowed to differentiate at air-liquid interface (ALI) demonstrate disparities in the response to particle exposure.

Results: Following exposure of submerged NHBE cells to ambient air pollution particle collected in Chapel Hill, NC, RNA for IL-8, IL-6, heme oxygenase 1 (HOX1) and cyclooxygenase 2 (COX2) increased. The same cells allowed to differentiate over 3, 10, and 21 days at ALI demonstrated no such changes following particle exposure. Similarly, BEAS-2B cells grown submerged in media demonstrated a significant increase in IL-8 and HOX1 RNA after exposure to NIST 1648 particle relative to the same cells exposed after growth at ALI. Subsequently, it was not possible to attribute the observed decreases in the response of NHBE cells to differentiation alone since BEAS-2B cells, which do not differentiate, showed similar changes when grown at ALI. With no exposure to particles, differentiation of NHBE cells at ALI over 3 to 21 days demonstrated significant decrements in baseline levels of RNA for the same proteins (i.e. IL-8, IL-6, HOX1, and COX2). With no exposure to particles, BEAS-2B cells grown at ALI showed comparable changes in RNA for IL-8 and HOX1. After the same particle exposure, NHBE cells grown at ALI 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 cells grown in 95% air-5% CO2.

Conclusions: We conclude that growth of NHBE cells at ALI is associated with a diminished biological effect following particle exposure relative to cells submerged in media. This decreased response showed an association with increased oxygen availability.

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Fold change RNA of NHBE cells for IL-8 (A), IL-6 (B), HOX1 (C), and COX2 (D) following exposure to fractions of Chapel Hill ambient air pollution particle. Significant increases in RNA were observed after exposure of submerged cells to the particles fractions. However, no increased RNA was observed following exposure of NHBE cells grown at ALI to the same particle. Data was statistically analyzed using a one way ANOVA only; no effect of either fraction or mass was evaluated. *Significant increase relative to RNA in unexposed NHBE cells.
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Figure 1: Fold change RNA of NHBE cells for IL-8 (A), IL-6 (B), HOX1 (C), and COX2 (D) following exposure to fractions of Chapel Hill ambient air pollution particle. Significant increases in RNA were observed after exposure of submerged cells to the particles fractions. However, no increased RNA was observed following exposure of NHBE cells grown at ALI to the same particle. Data was statistically analyzed using a one way ANOVA only; no effect of either fraction or mass was evaluated. *Significant increase relative to RNA in unexposed NHBE cells.

Mentions: Relative to submerged cells, NHBE cells grown at ALI for 21 days showed evidence of differentiation with 18.6 ± 3.9 and 11.8 ± 3.0 fold increased RNA for alpha tubulin and muc5b respectively[6]. NHBE cells grown submerged in media demonstrated a significant increase in RNA for the pro-inflammatory mediators IL-8 and IL-6 at 4 hr following exposure to ambient air pollution particle collected from Chapel Hill, North Carolina (Figures 1A and1B). Elevations in IL-8 and IL-6 RNA were greatest following exposure to the coarse fraction in Chapel Hill particle. NHBE cells allowed to differentiate at ALI demonstrated no elevations in RNA for IL-8 and IL-6 at 4 hr after PM exposure (Figures 1A and1B). Similarly, there was increased RNA for two proteins involved in oxidative stress at 4 hr following exposure of submerged NHBE cells to particles (Figures 1C and1D). Those cells which differentiated at ALI did not show such elevations in HOX1 and COX2 after exposure to PM except day 21 transwell cultures exposed to the higher dose of coarse particle (Figures 1C and1D).


Growth of human bronchial epithelial cells at an air-liquid interface alters the response to particle exposure.

Ghio AJ, Dailey LA, Soukup JM, Stonehuerner J, Richards JH, Devlin RB - Part Fibre Toxicol (2013)

Fold change RNA of NHBE cells for IL-8 (A), IL-6 (B), HOX1 (C), and COX2 (D) following exposure to fractions of Chapel Hill ambient air pollution particle. Significant increases in RNA were observed after exposure of submerged cells to the particles fractions. However, no increased RNA was observed following exposure of NHBE cells grown at ALI to the same particle. Data was statistically analyzed using a one way ANOVA only; no effect of either fraction or mass was evaluated. *Significant increase relative to RNA in unexposed NHBE cells.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750262&req=5

Figure 1: Fold change RNA of NHBE cells for IL-8 (A), IL-6 (B), HOX1 (C), and COX2 (D) following exposure to fractions of Chapel Hill ambient air pollution particle. Significant increases in RNA were observed after exposure of submerged cells to the particles fractions. However, no increased RNA was observed following exposure of NHBE cells grown at ALI to the same particle. Data was statistically analyzed using a one way ANOVA only; no effect of either fraction or mass was evaluated. *Significant increase relative to RNA in unexposed NHBE cells.
Mentions: Relative to submerged cells, NHBE cells grown at ALI for 21 days showed evidence of differentiation with 18.6 ± 3.9 and 11.8 ± 3.0 fold increased RNA for alpha tubulin and muc5b respectively[6]. NHBE cells grown submerged in media demonstrated a significant increase in RNA for the pro-inflammatory mediators IL-8 and IL-6 at 4 hr following exposure to ambient air pollution particle collected from Chapel Hill, North Carolina (Figures 1A and1B). Elevations in IL-8 and IL-6 RNA were greatest following exposure to the coarse fraction in Chapel Hill particle. NHBE cells allowed to differentiate at ALI demonstrated no elevations in RNA for IL-8 and IL-6 at 4 hr after PM exposure (Figures 1A and1B). Similarly, there was increased RNA for two proteins involved in oxidative stress at 4 hr following exposure of submerged NHBE cells to particles (Figures 1C and1D). Those cells which differentiated at ALI did not show such elevations in HOX1 and COX2 after exposure to PM except day 21 transwell cultures exposed to the higher dose of coarse particle (Figures 1C and1D).

Bottom Line: Subsequently, it was not possible to attribute the observed decreases in the response of NHBE cells to differentiation alone since BEAS-2B cells, which do not differentiate, showed similar changes when grown at ALI.We conclude that growth of NHBE cells at ALI is associated with a diminished biological effect following particle exposure relative to cells submerged in media.This decreased response showed an association with increased oxygen availability.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Background: We tested the hypothesis that normal human bronchial epithelial (NHBE) cells 1) grown submerged in media and 2) allowed to differentiate at air-liquid interface (ALI) demonstrate disparities in the response to particle exposure.

Results: Following exposure of submerged NHBE cells to ambient air pollution particle collected in Chapel Hill, NC, RNA for IL-8, IL-6, heme oxygenase 1 (HOX1) and cyclooxygenase 2 (COX2) increased. The same cells allowed to differentiate over 3, 10, and 21 days at ALI demonstrated no such changes following particle exposure. Similarly, BEAS-2B cells grown submerged in media demonstrated a significant increase in IL-8 and HOX1 RNA after exposure to NIST 1648 particle relative to the same cells exposed after growth at ALI. Subsequently, it was not possible to attribute the observed decreases in the response of NHBE cells to differentiation alone since BEAS-2B cells, which do not differentiate, showed similar changes when grown at ALI. With no exposure to particles, differentiation of NHBE cells at ALI over 3 to 21 days demonstrated significant decrements in baseline levels of RNA for the same proteins (i.e. IL-8, IL-6, HOX1, and COX2). With no exposure to particles, BEAS-2B cells grown at ALI showed comparable changes in RNA for IL-8 and HOX1. After the same particle exposure, NHBE cells grown at ALI 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 cells grown in 95% air-5% CO2.

Conclusions: We conclude that growth of NHBE cells at ALI is associated with a diminished biological effect following particle exposure relative to cells submerged in media. This decreased response showed an association with increased oxygen availability.

Show MeSH
Related in: MedlinePlus