Autophagy regulates cellular homeostasis and integrates the cellular pro-survival machinery. We investigated the role of autophagy in the natural history of murine abdominal aortic aneurysms (AAA). ApoE−/− mice were implanted with saline- or angiotensin II (Ang-II)-filled miniosmotic pumps then treated with either the autophagy inhibitor chloroquine (CQ; 50 mg·(kg body mass)–1·day–1, by intraperitoneal injection) or saline. Ang-II-elicited aneurysmal expansion of the suprarenal aorta coupled with thrombus formation were apparent 8 weeks later. CQ had no impact on the incidence (50% for Ang-II compared with 46.2% for Ang-II + CQ; P = NS) and categorical distribution of aneurysms. The markedly reduced survival rate observed with Ang-II (57.1% for Ang-II compared with 100% for saline; P < 0.05) was unaffected by CQ (61.5% for Ang-II + CQ; P = NS compared with Ang-II). CQ did not affect the mean maximum suprarenal aortic diameter (1.91 ± 0.19 mm for Ang-II compared with 1.97 ± 0.21 mm for Ang-II + CQ; P = NS). Elastin fragmentation, collagen accumulation, and smooth muscle attrition, which were higher in Ang-II-treated mice, were unaffected by CQ treatment. Long-term CQ administration does not affect the natural history and prognosis of experimental AAA, suggesting that global loss of autophagy is unlikely to be a causal factor in the development of aortic aneurysms. Manipulation of autophagy as a mechanism to reduce AAA may need re-evaluation.
Natural history of thoracic aortic aneurysms