Macrophage-Derived Angiopoietin-Like Protein 2 Accelerates Development of Abdominal Aortic Aneurysm

Objective—Recently, we reported that angiopoietin-like protein 2 (Angptl2) functions in various chronic inflammatory diseases. In the present study, we asked whether Angptl2 and its associated chronic inflammation contribute to abdominal aortic aneurysm (AAA). Methods and Results—Immunohistochemistry revealed that Angptl2 is abundantly expressed in infiltrating macrophages within the vessel wall of patients with AAA and in a CaCl2-induced AAA mouse model. When Angptl2-deficient mice were used in the mouse model, they showed decreased AAA development compared with wild-type mice, as evidenced by reduction in aneurysmal size, less severe destruction of vessel structure, and lower expression of proinflammatory cytokines and matrix metalloproteinase-9. However, no difference in the number of infiltrating macrophages within the aortic aneurysmal vessel wall was observed between genotypes. AAA development was also significantly suppressed in wild-type mice that underwent Angptl2-deficient bone marrow transplant...