Peroxisome proliferator-activated receptor alpha gene variants influence progression of coronary atherosclerosis and risk of coronary artery disease.

BACKGROUND: Peroxisome proliferator-activated receptor alpha (PPARalpha) regulates the expression of genes involved in lipid metabolism and inflammation, making it a candidate gene for atherosclerosis and ischemic heart disease (IHD). METHODS AND RESULTS: We investigated the association between the leucine 162 to valine (L162V) polymorphism and a G to C transversion in intron 7 of the PPARalpha gene and progression of atherosclerosis in the Lopid Coronary Angiography Trial (LOCAT), a trial examining the effect of gemfibrozil treatment on progression of atherosclerosis after bypass surgery and on risk of IHD in the second Northwick Park Heart Study (NPHS2), a prospective study of healthy middle-aged men in the United Kingdom. There was no association with plasma lipid concentrations in either study. Both polymorphisms influenced progression of atherosclerosis and risk of IHD. V162 allele carriers had less progression of diffuse atherosclerosis than did L162 allele homozygotes with a similar trend for focal atherosclerosis. Intron 7 C allele carriers had greater progression of atherosclerosis than did G allele homozygotes. The V162 allele attenuated the proatherosclerotic effect of the intron 7 C allele. Homozygotes for the intron 7 C allele had increased risk of IHD, an effect modulated by the L162V polymorphism CONCLUSIONS: The PPARalpha gene affects progression of atherosclerosis and risk of IHD. Absence of association with plasma lipid concentrations suggests that PPARalpha affects atherosclerotic progression directly in the vessel wall.

Progression of atherosclerosis is associated with variation in the alpha1-antitrypsin gene.

OBJECTIVE: Alpha1-Antitrypsin (AAT) protects elastic tissue and may play a role in atherogenesis. The association of atherosclerosis progression with common AAT variants was considered in 2 clinical trials. METHODS AND RESULTS: We examined the association of AAT V213A, S and Z deficiency alleles, and the functional 3' UTR 11478G>A with change in minimal luminal diameter, a measure of focal disease, in the Lopid Coronary Angiography Trial gemfibrozil study of post-bypass men. S or Z carriers (n=14) showed strong progression of disease on placebo (11.5%) but responded well to treatment (3% regression). 11478A carriers treated with placebo or gemfibrozil showed significantly more disease progression (n=8, -14.5% and n=16, -4.0%, respectively) than 11478GG men (n=107, -7.0% and n=108, -1.4%, respectively; overall, P=0.003). VV213 men treated with gemfibrozil (n=68) showed -4.8% progression, whereas A213 carriers (n=55) showed +1.4% regression of disease (P=0.001). No V213A effect was seen on placebo (P=0.11). In the Diabetes Atherosclerosis Intervention Study fenofibrate trial of angiographic progression in type 2 diabetes, the association of 11478A with increased disease progression was confirmed in the treatment group, but not the gemfibrozil-treated A213 association with regression, suggesting a pharmacogenetic difference. CONCLUSIONS: Disease progression is associated with variation in AAT, and low AAT levels promote atherogenesis.

Serum homocysteine concentrations, gemfibrozil treatment, and progression of coronary atherosclerosis.

The present study aimed to assess the effect of gemfibrozil on serum total homocysteine (tHcy) concentration and to evaluate the influence of tHcy on the angiographically determined progression of coronary atherosclerosis in a randomised, placebo-controlled trial of 395 post-coronary bypass men with low HDL cholesterol levels. The baseline levels of tHcy and those after 16 months of randomised therapy were measured by high-pressure liquid chromatography. Patients were genotyped for the thermolabile variant of N5,N10-methylenetetrahydrofolate reductase (MTHFR) (677C > T substitution). Gemfibrozil therapy was associated with a median 18% increase in tHcy levels (P < 0.01). In the gemfibrozil group increases in tHcy and HDL cholesterol were related (r = 0.217, P = 0.004), but changes in tHcy and triglycerides were not. Levels of tHCy were not associated with baseline extent or progression of coronary-artery disease. Subjects homozygous for the rare MTHFR T allele had 34% higher median tHcy concentrations than CC homozygotes or CT heterozygotes, but responses to gemfibrozil did not differ significantly among genotypes. The MTHFR genotype was not associated with extent or progression of coronary atherosclerosis. We conclude that gemfibrozil causes a significant elevation in tHcy levels, but the clinical relevance of this is unknown at present.

R643G polymorphism in PECAM-1 influences transendothelial migration of monocytes and is associated with progression of CHD and CHD events.

The 643R allele of R643G polymorphism (also known as R670G in the premature protein) in PECAM-1 has been associated with risk of myocardial infarction (MI), while the 643G allele has been associated with risk of coronary artery stenosis (CAS). The aim of this study was to investigate this apparently conflicting association. The association of R643G with risk of MI was determined in the second Northwick Park Heart study (2037 men with 138 CHD events; mean age: 56 years). Smokers homozygous for the 643R allele showed increased risk of MI with a hazard ratio of 2.47 (95% CI: 1.23-4.97; P=0.01) compared to smokers homozygous for the 643G allele. Progression of disease was determined in the Lopid Coronary Angiography Trial (279 men; mean age: 58.9 years). The 643G homozygotes showed greater focal (-0.08 +/- 0.02 mm) and diffuse (-0.01 +/- 0.01 mm) progression of CAS compared to 643R homozygotes (-0.02 +/- 0.02 mm and 0.001 +/- 0.01 mm, respectively; P=0.04). While there was no genotype effect on platelet aggregation, PECAM-1 tyrosine phosphorylation in HUVECs of GG genotype was 2.4-fold greater (P <0.01) than cells of RR genotype, and the level of transendothelial migration of monocytes of GG genotype was greater than that of monocytes of RR genotype following stimulation with either IL-1beta (12% higher, P <0.01) or TNF-alpha (10% higher, P=0.05). These data confirm the association of the R643G polymorphism with MI and CAS and suggest that greater influx of monocytes in individuals homozygous for the 643G may explain the association with CAS.

A novel functional polymorphism in the PECAM-1 gene (53G>A) is associated with progression of atherosclerosis in the LOCAT and REGRESS studies.

A 53G>A polymorphism identified in the 5' untranslated region (5'UTR) of the platelet endothelial cell adhesion molecule-1 (PECAM-1) gene alters a putative shear stress responsive element (SSRE). PECAM-1 was shown to be responsive to shear stress and transient transfection of human umbilical vein endothelial cell (HUVECs) with two luciferase reporter constructs driven by the PECAM-1 promoter and 5'UTR showed a response of the 53G allele, not the 53A allele, to shear stress. Association between the 53G>A, and the previously published L125V polymorphism, and coronary atherosclerosis was examined in two angiographic studies. The frequencies of the rare alleles of the 53G>A and L125V polymorphisms were 0.01 and 0.49, respectively, in the Lopid Coronary Angiography Trial (LOCAT) study and 0.02 and 0.49, respectively, in the Regression Growth Evaluation Statin Study (REGRESS) study. Compared with 53G homozygotes, carriers of the 53A allele showed less focal progression of disease in the LOCAT study and a similar trend in the diffuse progression of disease in the REGRESS study, whereas no association between L125V and coronary atherosclerosis was observed in either study. These data demonstrate that the PECAM-1 gene is responsive to shear stress in vitro and that decreased PECAM-1 gene expression in 53A carriers may influence reduced progression of vessel stenosis in patients with coronary artery disease.

APOA5 gene variants, lipoprotein particle distribution, and progression of coronary heart disease: results from the LOCAT study.

Animal and human studies support a role for apolipoprotein A-V (apoA-V) in triglyceride (TG) metabolism. We examined the relationship of APOA5 -1131T>C and S19W with lipid subfractions and progression of atherosclerosis in the Lopid Coronary Angiography Trial. Compared with -1131TT men (n = 242), carriers of the -1131C allele (n = 54) had significantly higher total TG (P = 0.03), reflected in significantly increased VLDL mass [higher VLDL-TG, VLDL-cholesterol, VLDL-protein, and surface lipids (all P < 0.05)]. Because apoB levels were unaffected by genotype, this suggests an increase in VLDL size and not number. Compared with 19SS men (n = 268), 19W carriers (n = 44) had higher intermediate density lipoprotein (IDL)-TG, IDL-cholesterol (P = 0.04), and IDL-surface components [free cholesterol (P = 0.005) and phospholipids (P = 0.017)] but not protein content, suggesting an increase in IDL lipid enrichment resulting in an increase in IDL size. 19W carriers also showed a trend toward increased progression of atherogenesis, as measured by change in average diameter of segments (-0.46 +/- 0.011 mm compared with -0.016 +/- 0.006 mm) in 19SS men (P = 0.08). There was no effect of genotype on the response of these parameters to gemfibrozil treatment. These results shed new light on the role of APOA5 variants in TG metabolism and coronary heart disease risk.