Evidence indicates that the arachidonate 5-lipoxyagense enzymatic pathway may play a pivotal role in cardiovascular disease. During this investigation, we achieved three aims. We developed a convenient and accurate pyrosequencing protocol for genotyping a repeat polymorphism in the ALOX5 gene. We also conducted genetic association studies in populations with both early and established heart disease to determine if genetic polymorphisms in 5LO pathway genes contribute to the variability in both the occurrence and outcomes in cardiovascular disease. Furthermore, we identified a population at risk for heart disease and tested the effect of a leukotriene pathway modifier to affect levels of biomarkers of cardiovascular risk.

We developed a method to genotype an important repeat polymorphism in the promoter region of the ALOX5 gene, which encodes 5-lipoxygenase. Genotyping this region has previously proven difficult by standard methods which has limited study of this polymorphism. The method presented here has been published and will facilitate future genetic association studies on this polymorphism.

In addition, we assessed whether genetic variation in the genes encoding the enzymes of the 5-lipoxygenase pathway contribute to cardiovascular disease in two populations. The first was in matched subjects from the Women’s Ischemia Syndrome Evaluation and the St. James Women Take Heart Project (WISE-WTH) case control study, representing early heart disease. The second were from the INternational VErapamil SR /Trandolapril Study GENEtic case-control Substudy (INVEST-GENES). In the INVEST-GENES population we assessed whether these polymorphisms promote death, myocardial infarction and/or stroke in treated hypertensive patients with coronary artery disease (CAD). We found an effect for ALOX5 and LTA4H polymorphisms to confer race-dependant effects on these outcomes in INVEST-GENES however these same associations were not observed in WISE-WTH.

We further conducted a double-blind placebo-controlled clinical study in subjects at risk for heart disease to determine the effect of pharmacological inhibition of the 5LO pathway leukotriene D₄ receptor by montelukast on cardiovascular biomarkers. In this pilot study, we identified an effect of montelukast to change levels IL1ra, an anti-inflammatory cytokine. Overall, we have generated tools and derived pilot information to help design future studies of the 5LO pathway in similar populations.