NADPH and xanthine oxidases control induction of inflammatory mediator expression by organic dust in the lung

Exposure to organic dust in animal and agricultural farms and the ensuing lung inflammation are linked to the development of respiratory diseases. We found previously that elevated production of reactive oxygen species (ROS) by aqueous poultry organic dust extract (hereafter referred to as dust extract) mediates induction of proinflammatory mediators in airway epithelial cells. In the present study, we investigated whether ROS generated by NADPH oxidases (NOX) and xanthine oxidase (XO) controls induction of inflammatory mediators by dust extract and the underlying mechanisms in bronchial epithelial cells. Using chemical inhibitors and siRNA targeted knockdown, we found that NOX1, NOX2, NOX4, and XO-derived ROS regulates induction of proinflammatory mediator levels. Like airway epithelial cells in vitro, NOX inhibitor VAS2870 reduced keratinocyte chemoattractant (KC), IL-6, and TNF-alpha production and 4-hydroxynonenal (4-HNE) staining induced by dust extract in mouse lungs. VAS2870 inhibition of proinflammatory mediators was associated with reduced NF kappa B and Stat3 activation indicating that NOX generated ROS activates NF kappa B and Stat3 to induce proinflammatory gene expression. Dust extract increased the membrane association of p47(phox) in airway epithelial cells indicating NOX2 activation but had no effect on NOX2 protein levels. In summary, our studies have shown that NOX and XO generated ROS control organic dust induction of proinflammatory mediators in airway epithelial cells via NF kappa B and Stat3 activation.

Automated summary

Exposure to organic dust in animal and agricultural farms is associated with the development of lung inflammation and respiratory diseases. This study investigates the role of reactive oxygen species (ROS) generated by NADPH oxidases (NOX) and xanthine oxidase (XO) in controlling the induction of inflammatory mediators by dust extract in bronchial epithelial cells. The findings suggest that NOX and XO-derived ROS activate NF kappa B and Stat3 to induce proinflammatory gene expression.