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Objective: Aortic macrophage accumulation is characteristic of the pathogenesis of abdominal aortic aneurysm (AAA) but the mechanisms of macrophage accumulation and their phenotype are poorly understood. Lymphatic vessel endothelial receptor-1 (Lyve-1⁺) resident aortic macrophages independently self-renew and are functionally distinct from monocyte-derived macrophages recruited during inflammation. We hypothesized that Lyve-1⁺ and Lyve-1⁻ macrophages differentially contribute to aortic aneurysm.

Approach and results: Angiotensin-2 and β-aminopropionitrile (AT2/BAPN) were administered to induce AAA in C57BL/6J mice. Using immunohistochemistry (IHC), we demonstrated primarily adventitial accumulation of aortic macrophages, and in association with areas of elastin fragmentation and aortic dissection. Compared with controls, AAA was associated with a relative percent …