COX-2 mediates PM2.5-induced apoptosis and inflammation in vascular endothelial cells

Emerging evidence demonstrated that particulate matter 2.5 (PM2.5) exposure served as an important risk factor of cardiovascular diseases. Some studies also reported that COX-2/mPGES-1/PGE2 cascade played a pathogenic role in vascular injury. However, the relationship between the PM2.5 exposure and the activation of COX-2/mPGES-1/PGE2 cascade in endothelial cells is still unknown. In the present study, mouse aorta endothelial cells were exposed to PM2.5. Strikingly, following the PM2.5 treatment, we observed dose- and time-dependent upregulation of COX-2 at both protein and mRNA levels as determined by Western blotting and qRT-PCR, respectively. However, COX-1 mRNA expression was not affected by PM2.5 treatment. Next, we examined mPGES-1 expression. As expected, mPGES-1 protein was markedly increased by PM2.5 exposure in line with a significant increment of PGE2 release in medium. At the same time, we observed a dose-dependent upregulation of another two PGE2 synthases of mPGES-2 and cPGES determined by qRT-PCR. Inhibition of COX-2 by using a specific COX-2 inhibitor NS-398 markedly blocked cell apoptosis, inflammation, and PGE2 secretion. Taken together, these results suggested that PM2.5 could activate inflammatory axis of COX-2/PGES/PGE2 in vascular endothelial cells to promote cell apoptosis and inflammatory response.