Abstract P246: Targeting 20-Hydroxyeicosatetraenoic Acid in Rofecoxib-induced Cerebrovascular Damage

Abstract

Background: Coxibs, selective cyclooxygenase-2 (COX-2) inhibitors, significantly improved the quality of life of millions of individuals affected by pain and inflammation. Unfortunately, increased risk of stroke with the use of coxibs limited their clinical usefulness. The goal of this study is to investigate the role of 20-hydroxyeicosatetraenoic acid (20-HETE) metabolism by COX-2 in rofecoxib-induced cerebrovascular damage. We treated MC38 mice (1.4 x 10 6 MC38 cells/mouse) with rofecoxib (50 mg/L) + HET0016 (20-HETE blocker; 5 mg/kg/day, i.p.), rofecoxib, or vehicle for 3 weeks. We then subjected these MC38 and control mice to thromboembolic stroke. Finally, we treated B6 mice with 20-OH PGE 2 (250 ng/h; osmotic pump) and vehicle for 7 days, and then subjected them to ischemic stroke. Results: 1 ). Rofecoxib significantly reduced MC38 tumor size (from 693 ± 106 to 329 ± 40 mm 3 , P < 0.05). Within its therapeutic dose, rofecoxib selectively increased circulating 20-HETE levels (100 ± 18 vs. 150 ± 11%, P < 0.05), which was reversed by HET0016 (150 ± 11 vs. 100 ± 16%, P < 0.05). We did not find significant change on cyp4a (20-HETE synthesizing enzymes) expression in the brain microvessels after rofecoxib treatment. 2 ). A major prostaglandin (PG) metabolite, which is 20-OH PGE 2 , was generated when we incubated purified COX-2 with 20-HETE (5 uM). Strikingly, rofecoxib (1 uM) inhibited 20-OH PGE 2 synthesis by 71% (from 100 ± 16 to 29 ± 8%, P < 0.05). 3 ). Hemorrhagic transformation (HT) was greater in rofecoxib group (4/5 mice showing bleeding), a vascular injury that was prevented by co-treatment with HET0016 (0/6 mice showing bleeding). 4 ). 20-OH PGE 2 supplementation reduced both infarct size (45 ± 10 vs. 17 ± 8% contralateral hemisphere, P < 0.05) and neurological deficits (3.6 ± 0.5 vs. 2 ± 1, P < 0.05). Conclusion: 1 ) Rofecoxib increases circulating levels of 20-HETE, which exacerbates stroke damage. 2 ) COX-2 is the key player in regulating 20-HETE metabolism. 3 ) 20-HETE blockade prevents HT induced by rofecoxib. 4 ) 20-OH PGE 2 exerts cerebroprotective after ischemic stroke. In summary , these results suggest that both 20-HETE blockade and 20-OH PGE 2 supplementation are new approaches to ameliorate coxib-induced cerebrovascular damage and adverse stroke outcomes.