Abstract 586: CCR2+ Macrophages Are Elevated In Individuals With Aortic Aneurysmal And Occlusive Disease

Background: Mounting evidence suggests that inflammation plays a key role in arterial pathophysiology. C-C chemokine receptor type 2 (CCR2) is essential for recruitment of macrophages to regions of inflammation. Therefore, we hypothesized that CCR2 and macrophage content will be elevated in human aortic tissue from individuals with aneurysmal or occlusive disease. Methods: We conducted a retrospective review of prospectively collected human aortic tissue from our institutional review board-approved vascular biobank to include male, non-diabetic cases with active or recent history of smoking. Diseased aortic tissue was collected from individuals with aortic occlusive disease (AOD), ruptured abdominal aortic aneurysm (rAAA), and non-ruptured AAA. Normal non-diseased abdominal aorta (NAA) was harvested from organ donors. All tissue were fixed in formalin, paraffin-embedded, sectioned, and immune-stained for CCR2 and CD68 (macrophage marker). Two blinded observers evaluated the content of CCR2+ and/or CD68+ cells in three randomly selected 0.1mm2 regions of interest within the arterial intima and media. Cell counts were averaged and analyzed. Results: A total of 19 aortic tissue samples were studied; including 5 NAA, 8 AAA (56 to 89 mm diameter), 3 rAAA, and 3 AOD. We observed significantly higher CCR2+ cells in rAAA compared with NAA (p < 0.05) (Fig, A). In addition, patients with AAA demonstrated higher CD68+ and CCR2+ CD68+ cells (p < 0.05) (Fig, B, C). Interestingly, only up to half of CCR2+ cells that were observed in diseased aortic tissue (AAA, rAAA, and AOD) co-localized with CD68+ cells, indicating that CCR2 may also be expressed by other cell types. Conclusions: CCR2-expressing macrophages are increased in diseased aortic tissue, and CCR2 cellular content is associated with AAA rupture risk and appears to correlate with disease severity. Therefore, CCR2 represents a potential tissue biomarker for aortic disease molecular imaging and targeted therapy.