Figure 11.

Proposed signaling pathways of ROS-dependent and -independent activation of COX-2 in PM-induced IL-6 secretion in HBEpCs. Exposure of epithelium to PM results in ROS generation and activation of NF-κB, which regulates COX-2 and IL-6 secretion. PM-induced expression of COX-2 enhances PGE2 that stimulates IL-6 in HBEpCs. Independent of ROS generation, PM also stimulates COX-2 expression via C/EBPβ signaling. These results suggest multiple pathways involved in ambient PM–mediated IL-6 generation in airway epithelium, which involve ROS-dependent and -independent activation of COX-2 and PGE2 signal transduction.