Objective— Inflammation plays an integral role in the development of abdominal aortic aneurysms (AAAs), and the expression of cyclooxygenase (COX)-2 is increased in aneurysmal tissue compared with normal aorta. Nonsteroidal anti-inflammatory drugs, which inhibit the activity of COX-1 and COX-2, decrease AAA expansion in humans and animal models of the disease. In the current study, we investigated the effectiveness of selective inhibition of COX-1 or COX-2 in attenuating AAA formation.

Methods and Results— Eight-week-old male apolipoprotein E-deficient mice were treated with selective inhibitors of COX-1 or COX-2, SC-560 (≈25 mg · kg⁻¹ · day⁻¹), or celecoxib (≈125 mg · kg⁻¹ · day⁻¹), respectively. COX inhibitors were administered 1 week before angiotensin II (Ang II; 1000 ng · kg⁻¹ · min⁻¹) or saline infusion and throughout the time course of the experiment. COX-1 inhibition had no effect on incidence (control: 90% [9:10] versus SC-560: 89% [8:9]) or severity of Ang II-induced AAA formation. In contrast, celecoxib decreased the incidence (control: 74% [22:30] versus celecoxib: 11% [2:19]; P<0.001) and severity (P=0.001) of AAA formation. Celecoxib also decreased the incidence and severity of AAAs in nonhyperlipidemic mice.

Conclusions— COX-2–derived prostanoids play a fundamental role in the development of Ang II-induced AAAs in both hyperlipidemic and nonhyperlipidemic mice.