MMP2 and medical procedure: The present study supports a novel model that exposure to PM can lead to an increase in the expression and secretion of IL-6 regulated by the TLR2 and TLR4/NADPH oxidase/ROS/NF-κB signaling pathway, which then enhances the expression of cell adhesion molecules (ICAM-1 and VCAM-1) and MMPs (MMP-2 and MMP-9), thereby promoting monocyte adhesion and HASMC migration that are implicated in the development of aorta inflammation.