The relationship between active proteolytic enzymes and intraluminal thrombus in human abdominal aortic aneurysms
We have previously shown that the region of abdominal aortic aneurysms (AAA) containing intraluminal thrombus may be at higher risk of rupture. The purpose of this study is to evaluate differential expression of macrophage derived protease and cytokines across the aneurysm, to evaluate the regional differences in AAA that may contribute to rupture. Full thickness tissue samples were collected from twenty-one participants using a systematic map, including specimens from thrombus adjacent and thrombus free wall. Protein array was performed for matrix metalloproteinase (MMP)-12, interleukin (IL)-6, IL-10, and macrophage chemoattractant protein (MCP)-1. Eight participants undergoing aortobifemoral bypass for aortoiliac occlusive disease were included as control. We demonstrated inflammation, specifically CD68+ macrophage are elevated in thrombus adjacent AAA compared to control. This supports the body of literature identify AAA as an inflammatory process. Contrary to our hypothesis, there was no difference in inflammation between ILT and non ILT containing regions of the AAA. There was additionally no difference in MMP-12, IL-6, IL-10 and MCP-1 between regions of high ILT, no ILT, and control. This suggests that in addition to presence, macrophage function may also not significantly differ between regions of the AAA. These results propose that while inflammation is a hallmark of AAA, macrophage may play a limited role in AAA rupture.
Abdominal aortic aneurysms (AAA), Macrophage metalloelastase (MMP-12)