Critical roles of macrophages in the formation of intracranial aneurysm
Background and Purpose-Abnormal vascular remodeling triggered by hemodynamic stresses and inflammation is believed to be a key process in the pathophysiology of intracranial aneurysms. Numerous studies have shown infiltration of inflammatory cells, especially macrophages, into intracranial aneurysmal walls in humans. Using a mouse model of intracranial aneurysms, we tested whether macrophages play critical roles in the formation of intracranial aneurysms. Methods-Intracranial aneurysms were induced in adult male mice using a combination of a single injection of elastase into the cerebrospinal fluid and angiotensin II-induced hypertension. Aneurysm formation was assessed 3 weeks later. Roles of macrophages were assessed using clodronate liposome-induced macrophage depletion. In addition, the incidence of aneurysms was assessed in mice lacking monocyte chemotactic protein-1 (CCL2) and mice lacking matrix metalloproteinase-12 (macrophage elastase). Results-Intracranial aneurysms in this model showed leukocyte infiltration into the aneurysmal wall, the majority of the leukocytes being macrophages. Mice with macrophage depletion had a significantly reduced incidence of aneurysms compared with control mice (1 of 10 versus 6 of 10; P<0.05). Similarly, there was a reduced incidence of aneurysms in mice lacking monocyte chemotactic protein-1 compared with the incidence of aneurysms in wild-type mice (2 of 10 versus 14 of 20, P<0.05). There was no difference in the incidence of aneurysms between mice lacking matrix metalloproteinase-12 and wild-type mice. Conclusions-These data suggest critical roles of macrophages and proper macrophage functions in the formation of intracranial aneurysms in this model. © 2010 American Heart Association, Inc.
Digital Object Identifier (DOI)
Kanematsu, Yasuhisa; Kanematsu, Miyuki; Kurihara, Chie; Tada, Yoshiteru; Tsou, Tsung Ling; Van Rooijen, Nico; Lawton, Michael T.; Young, William L.; Liang, Elena I.; Nuki, Yoshitsugu; and Hashimoto, Tomoki, "Critical roles of macrophages in the formation of intracranial aneurysm" (2011). Neurosurgery. 1010.