Can COX-2 inhibitor-induced increase in cardiovascular disease risk be modified by essential fatty acids?

ABSTRACT

Selective COX-2 inhibitors increase the risk of myocardial infarction and stroke. This has been attributed to their ability to inhibit endothelial COX-2 derived prostacyclin (PGI2) but not platelet COX-1 derived thromboxane A2 (TXA2). On the other hand, aspirin blocks both COX-1 and COX-2 enzymes without decreasing PGI2 but blocks TXA2 synthesis that explains its beneficial action in the prevention of coronary heart disease (CHD). The inhibitory action of aspirin on COX-1 and COX-2 enzymes enhances the tissue concentrations of dihomo-gamma-linolenic acid (DGLA), arachidonic acid, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA). These fatty acids form precursors to PGE1, PGI2, PGI3, lipoxins (LXs), and resolvins that have anti-inflammatory actions. In contrast, increase in the concentrations of DGLA, AA, EPA, and DHA is much less with specific COX-2 inhibitors since they do not block the formation of eicosanoids through COX-1 pathway. COX-2 inhibitors interfere with the formation of LXs and resolvins that have neuroprotective and cardioprotective actions. EPA and PGI2 have anti-arrhythmic action. EPA, DHA, and AA augment eNO formation that prevents atherosclerosis. This suggests that COX-2 inhibitors increase cardiovascular and stroke risk by interfering with the formation of eNO, PGI2, LXs, and resolvins and implies that combining EFAs with COX-2 inhibitors could prevent these complications.