Infection with Staphylococcus aureus elicits COX-2/PGE₂/IL-6/MMP-9-dependent aorta inflammation via the inhibition of intracellular ROS production

Staphylococcus aureus (S. aureus) can lead to many life-threatening diseases. It has the ability to invade normal endovascular tissue. The molecular mechanisms and pathological changes of endothelial cells after S. aureus infection are of interest, but the basic understanding of how S. aureus destroys this barrier is not clear. Here, we showed that S. aureus enhanced COX-2 expression and prostaglandin E₂ (PGE₂) secretion in human aortic endothelial cells (HAECs). In addition, S. aureus induced PGE₂/interleukin-6 (IL-6)/matrix metallopeptidase-9 (MMP-9)-dependent cell migration. S. aureus-induced COX-2, IL-6, and MMP-9 levels were inhibited by transfection with siRNA of Toll-like receptor 2 (TLR2), p38, p42, p44, p50, or p65. S. aureus also induced p38 MAPK, ATF2, ERK1/2, and NF-κB p65 activation. Interestingly, we proved that S. aureus decreased intracellular generation of reactive oxygen species (ROS), which suggests that the inhibition of ROS production promoted inflammatory responses. Finally, we showed that S. aureus enhanced a variety of biomarkers of inflammation in cardiovascular diseases. However, the free radical scavenger (MCI-186) or antioxidant (N-acetyl-L-cysteine, NAC) markedly enhanced S. aureus-induced COX-2 mRNA levels in the aorta tissues. Taken together, these findings established that S. aureus promoted aorta inflammation via activation of p38 MAPK, ERK1/2, and NF-κB and inhibition of ROS generation.