TNF and aortic aneurysm: When macrophages infiltrate the aortic aneurysm wall, they express many inflammatory factors that can promote VSMC-apoptosis, such as interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), and monocyte chemotaxis protein-1 (MCP-1) (Hsieh et al., 2001).