Figure 8.

Schematic diagram illustrating the possible mechanism of cytochrome P450 (CYP) 1B1–dependent angiotensin (Ang) II–induced abdominal aortic aneurysm formation. Ang II via CYP1B1-mediated reactive oxygen species (ROS) generation and cyclooxygenase (COX)-2 expression, and inflammatory changes, characterized by enhanced infiltration of CD192⁺ monocytes and T cells, are accompanied by increased platelet infiltration and activation. These events, combined with the actions of Ang II to induce vascular smooth muscle cell proliferation and migration, result in elevated platelet-derived growth factor (PDGF)-D expression by various cell types, and enhanced signaling via Itga2 and Pdgfrb, resulting in enhanced matrix metalloproteinase (MMP) expression, which by acting on the medial layer causes degradation of extracellular matrix (ECM) components, leading to generation of aneurysm.