High-dose specific omega-3 polyunsaturated fatty acid increases plaque stability in tandem-stenosis ApoE-deficient mice fed high fat-diet.

Abstract

Background and Aims: Omega-3 polyunsaturated fatty acids have long been associated with cardioprotective benefits, including having anti-inflammatory and antioxidant effects. However, large-scale randomised-controlled cardiovascular outcomes trials have shown greatest benefit from treatment with high-dose, pure eicosapentaenoic acid (EPA), while high dose mixed omega 3 fatty acids do not appear to be effective in reducing major cardiovascular adverse events. We aimed to conduct a head-head comparison between treatment with EPA or docosahexanoic acid (DHA) in plaque development and vulnerability using a carotid artery plaque rupture-prone model in mice. Method(s): Apolipoprotein E (apoE)-/- mice were fed a high fat and high cholesterol diet from 8 weeks of age. After 6 weeks, mice underwent surgical implantation of dual ligatures 3 mm apart with 150 um diameter in the right common carotid artery to create turbulent blood flow, leading to the development of rupture-prone plaque. 3 weeks post surgery, daily treatment with high-dose EPA or DHA (600 mg/kg/day, oral) commenced. After 4 weeks of treatment, the diseased right carotid arteries and contralateral healthy left carotid arteries were isolated and frozen in OCT buffer. Arteries were then serially cryosectioned and stained with H&E or picrosirius red to determine the effect of omega-3 fatty acids on the development of the atherosclerotic lesions. Analysis of circulating fatty acids and inflammatory factors were measured and flow cytometry was conducted on plasma and lysed spleen and bone marrow to assess proportions of immune cells. Result(s): Blood levels of EPA and DHA were increased compared to control. EPA reduced circulating pro-inflammatory arachidonic acid (P<0.0001) and omega-6, leading to reduced omega-6:omega-3 ratio (P<0.0001). Plaque burden was similar in all mice, yet fibrous cap thickness, was increased in mice treated with EPA (0.0068 +/- 0.0014). Conclusion(s): This study supports the concept that EPA may have an atheroprotective role by lowering inflammatory signalling and thereby increasing plaque stability.Copyright © 2024