A bdominal aortic aneurysm (AAA) is a common vascular disease, which occurs in ≈4% to 8% of men aged 65 to 80 years.1 Aortic rupture is the most feared clinical consequence of AAA progression, resulting in mortality in ≈90% of cases. [2][3][4] Because AAA usually progresses without symptoms, AAA is often discovered in advanced stage. At present, surgical aortic replacement and endovascular stent graft repair are performed as standard definitive therapies for AAA. However, there is no effective medical therapy to prevent aortic rupture in AAA. Although several studies have reported the pathophysiology of AAA, the mechanisms of AAA formation are largely unknown. Therefore, it is necessary to investigate the molecular pathophysiology of AAA to find noninvasive strategies for the prevention of AAA.Iron is an essential element for maintaining physiological function. However, excess iron causes tissue damage by oxidative stress via the Fenton/Haber-Weiss reaction.
5Therefore, iron is involved in the pathophysiology of several diseases including cardiovascular diseases. In fact, we have previously shown that iron accumulation and superoxide production are observed in the renal tubules of a rat model of chronic kidney disease.6 Lee et al 7 have shown that iron accumulation is observed in the atherosclerotic lesions of apolipoprotein E knockout mice. Most recently, Martinez-Pinna et al 8 have demonstrated that iron is deposited in human AAA walls. Meanwhile, we have also reported that dietary iron restriction (IR) prevents the development of hypertension and proteinuria with inhibition of oxidative stress and inflammation in Dahl salt-sensitive hypertensive rats.9 Although oxidative stress and inflammation are well known to be involved in the development of AAA formation, it has not been investigated whether iron is associated with the pathophysiology of AAA through © 2015 American Heart Association, Inc. Objective-Although iron is an essential element for maintaining physiological function, excess iron leads to tissue damage caused by oxidative stress and inflammation. Oxidative stress and inflammation play critical roles for the development of abdominal aortic aneurysm (AAA). However, it has not been investigated whether iron plays a role in AAA formation through oxidative stress and inflammation. We, therefore, examined whether iron is involved in the pathophysiology of AAA formation using human AAA walls and murine AAA models. Approach and Results-Human aortic walls were collected from 53 patients who underwent cardiovascular surgery (non-AAA=34; AAA=19). Murine AAA was induced by infusion of angiotensin II to apolipoprotein E knockout mice. Iron was accumulated in human and murine AAA walls compared with non-AAA walls. Immunohistochemistry showed that both 8-hydroxy-2′-deoxyguanosine and CD68-positive areas were increased in AAA walls compared with non-AAA walls. The extent of iron accumulated area positively correlated with that of 8-hydroxy-2′-deoxyguanosine expression area and macrophage infiltration area in huma...