Dissociation between the effects of oxygen and pressure on matrix metalloproteinase-2, -7, and -9 expression in human airway epithelial cells

We tested the hypothesis that hyperoxia or pressure exposure differentially activates expression of cytokines and/or matrix modeling proteins in human airway epithelial cells. Calu-3 epithelial cell monolayers were cultured on transwell plates with the apical surface exposed to gas. Following establishment of baseline, plates were placed in a chamber and exposed to: control (21% O₂; atm), hyperoxia (60% O₂; atm), pressure (21% O ₂; 40 cm H₂O), and combination (60% O₂; 40 cm H₂O). At 72 hour of exposure, monolayers were assessed for integrity, viability, and expression of interleukin (IL)-6, IL-8 and matrix metalloproteinases (MMPs) -2, -7, and -9. Compared with controls, hyperoxia had lower transepithelial resistance (p < 0.001) and greater IL-6 secretion (p < 0.01), and pressure had lower cell viability (p < 0.001) and greater IL-8 secretion (p < 0.001). Hyperoxia resulted in more latent MMP-2 (p < 0.05) and MMP-7 (p < 0.001). Pressure was associated with a rise in MMPs independent of oxygen exposure (p < 0.05). Hyperoxia and pressure differentially affected MMP activities in Calu-3 cells and may lead to the different functional and structural abnormalities observed in these in vitro studies.