Yue-Mei Fan

The effect of hormone replacement therapy on atherosclerotic severity in relation to ESR1 genotype in postmenopausal women

OBJECTIVE The atheroprotective action of estrogen is mediated by estrogen receptors (ESR) 1 and 2, expressed in atherosclerotic lesions. The effects of hormone replacement therapy (HRT) and ESR1 PvuII genotypes on atherosclerosis have not previously been studied prospectively in postmenopausal women. METHODS We investigated the effect of HRT on the progression of atherosclerosis in a 5-year follow-up study of 88 postmenopausal women aged 45-71 years at baseline allocated into three groups based on the use of HRT. The HRT-EVP group (n=26) used sequential estradiol valerate (EV) plus progestin (P), the HRT-EV group EV alone (n=32), and a control group (n=30) was without HRT. The atherosclerosis severity score (AS) of the abdominal aorta and carotid arteries were determined by sonography and the ESR1 PvuII genotypes (P/P, P/p and p/p) by PCR. RESULTS HRT, time and ESR1 PvuII genotype had a statistically significant or borderline significant main effect on AS during 5-year follow-up (P=0.004, P<0.001 and P=0.090, respectively), when analyzed by repeated measures analysis of variance. There was a significant genotype-by-treatment (HRT-EVP and control groups) interaction for AS (P=0.034). In response to HRT-EVP, subjects with P/P, compared with those with P/p and p/p genotypes, had a less increase in AS (1.61+/-1.14 vs. 1.71+/-1.27 vs. 2.43+/-1.27). Baseline AS as covariate in similar model does not change the significant interaction effect between HRT-EVP and control groups (P=0.036). But this effect was not found between HRT-EV and control groups. CONCLUSIONS Our results suggest that the effect of HRT-EVP in postmenopausal women on progression of AS may be determined in part by the genotype of ESR1 PvuII.

Hepatic lipase gene variation is related to coronary reactivity in healthy young men.

Background Impaired coronary flow reserve (CFR) can be used to indicate vascular dysfunction before the appearance of angiographic lesions. The hepatic lipase (HL) gene has a functional promoter polymorphism at position C‐480T, which affects transcription and leads to high activity (C/C) and low activity (C/T, T/T) genotypes. These genotypes modulate HL activity, but their role in coronary artery disease is controversial and the effect on coronary function has not been studied. We investigated whether HL genotypes are associated with coronary artery function in healthy young men.

Genetic Variants and Their Interactions in the Prediction of Increased Pre-Clinical Carotid Atherosclerosis: The Cardiovascular Risk in Young Finns Study

The relative contribution of genetic risk factors to the progression of subclinical atherosclerosis is poorly understood. It is likely that multiple variants are implicated in the development of atherosclerosis, but the subtle genotypic and phenotypic differences are beyond the reach of the conventional case-control designs and the statistical significance testing procedures being used in most association studies. Our objective here was to investigate whether an alternative approach—in which common disorders are treated as quantitative phenotypes that are continuously distributed over a population—can reveal predictive insights into the early atherosclerosis, as assessed using ultrasound imaging-based quantitative measurement of carotid artery intima-media thickness (IMT). Using our population-based follow-up study of atherosclerosis precursors as a basis for sampling subjects with gradually increasing IMT levels, we searched for such subsets of genetic variants and their interactions that are the most predictive of the various risk classes, rather than using exclusively those variants meeting a stringent level of statistical significance. The area under the receiver operating characteristic curve (AUC) was used to evaluate the predictive value of the variants, and cross-validation was used to assess how well the predictive models will generalize to other subsets of subjects. By means of our predictive modeling framework with machine learning-based SNP selection, we could improve the prediction of the extreme classes of atherosclerosis risk and progression over a 6-year period (average AUC 0.844 and 0.761), compared to that of using conventional cardiovascular risk factors alone (average AUC 0.741 and 0.629), or when combined with the statistically significant variants (average AUC 0.762 and 0.651). The predictive accuracy remained relatively high in an independent validation set of subjects (average decrease of 0.043). These results demonstrate that the modeling framework can utilize the “gray zone” of genetic variation in the classification of subjects with different degrees of risk of developing atherosclerosis.

Hepatic lipase promoter C-480T polymorphism is associated with serum lipids levels, but not subclinical atherosclerosis: the Cardiovascular Risk in Young Finns Study.

The common C‐480T polymorphism (rs1800588) of the hepatic lipase gene (LIPC) has been associated with high‐density lipoprotein (HDL) cholesterol, atherosclerosis, and coronary artery disease. In this study, we examined whether the polymorphism is associated with serum lipid and lipoprotein concentrations, as well as with subclinical atherosclerosis in Young Finns. The participants comprised 2041 men and women (aged 24–39 years) enrolled in the Cardiovascular Risk in Young Finns Study with complete data concerning the rs1800588 polymorphism and serum lipids concentration. All participants underwent an ultrasound examination for brachial artery flow‐mediated vasodilatation (FMD) and carotid artery intima‐media thickness (IMT) measurement. The marker of arterial elasticity, carotid artery compliance (CAC), was also calculated by means of ultrasound and concomitant brachial blood pressure measurements. In all subjects, serum total cholesterol (p < 0.001), HDL cholesterol (p = 0.006), apolipoprotein AI (apoAI, p < 0.001), and triglyceride (p = 0.009) concentrations increased according to rs1800588 genotype in the order CC, CT, and TT. The same order applied only to apoAI after adjustment for age, body mass index, systolic and diastolic blood pressure, smoking, alcohol consumption, physical activity, diabetes, hypertension, contraceptive hormone use in women, and concentrations of glucose, insulin and C‐reactive protein in men and women separately (p = 0.007 and p = 0.003, respectively). The polymorphism was also associated with HDL cholesterol, total cholesterol, and triglyceride levels in women (adjusted p = 0.004, p = 0.007 and 0.02, respectively), but not in men (p was not significant for all). No significant association between the rs1800588 and brachial FMD, carotid IMT, or CAC was found among the entire study population or among women or men separately, with or without adjustment for the above‐mentioned factors. The rs1800588 is associated with serum lipid and apolipoprotein concentrations, especially in women, but does not seem to be a determinant of brachial artery FMD, carotid IMT, or CAC in young healthy adults.

Effects of pravastatin therapy on serum lipids and coronary reactivity are not associated with SREBP cleavage-activating protein polymorphism in healthy young men

To the Editor: Sterol regulatory element binding protein (SREBP) cleavage-activating protein (SCAP) is a key regulator of cellular lipid homeostasis orchestrated by SREBP (1). The SCAP gene has an exonic polymorphism (A-to-G transition) leading to isoleucine (A) to valine (G) substitution at codon 796 (2). This polymorphism is localised in the WD domain of SCAP and therefore might affect protein– protein interaction between SCAP and SREBP (3). It is possible that these SCAP variants may alter lipid synthesis and therefore cause changes in circulating lipid levels due to altered SCAP function. On the other hand, SCAP variants may not affect circulating lipids, as increased SCAP activity increases cholesterol synthesis and low-density lipoprotein (LDL) receptor mediated cholesteroluptake, so that the net effect on serum lipids is small. Thus, we investigated the relationship between SCAP variants and serum lipid levels. Furthermore, it has been suggested that statins may affect SREBP mediated lipid synthesis (4). This poses the second question, i.e. whether SCAP variants could alter the lipid lowering effects of statins. Previously, it has been shown that statins not only lower elevated levels of total cholesterol and LDL cholesterol, but that they also can modify endothelial function (5–8). Endothelial dysfunction and impairment of coronary flow reserve (CFR) are among the earliest manifestations of atherosclerosis and coronary artery disease. CFR is an integrating marker of endothelial function and smooth muscle relaxation and therefore reflects coronary reactivity (9). As altered regulation of cellular lipid synthesis may not affect circulating lipid levels, we measured CFR both before and after pravastatin therapy. Thus, we studied whether SCAP variants could affect vascular functions due to differences in cellular lipid balance. Therefore, in the present study, we examined whether or not the Ile796Val polymorphism of SCAP can affect lipid levels and coronary reactivity and play a role in the cholesterol lowering effect of pravastatin by using positron emission tomography (PET) and [O] H2O in mildly hypercholesterolemic but healthy young men. We investigated 51 men, which were randomised in two groups receiving 40 mg pravastatin per day or placebo for 6 months. All subjects completed the follow-up. However, 6 of them were excluded from the final analysis due to technical problems with the PET studies. Study participants did not receive any drug therapy or antioxidant vitamins. All participants had normal electrocardiogram at rest and at pharmacological stress. They had normal or mildly elevated serum total cholesterol level averaging 5.5 0.8 mmol/l but were otherwise healthy. Myocardial blood flow at rest and after adenosine infusion was measured with PET at baseline and at follow-up. Lipid analyses were also performed at baseline and at follow-up. Total cholesterol, plasma triglycerides and high-density lipoprotein (HDL) cholesterol were measured by Cobas Integra 700 automatic analyser. LDL cholesterol was calculated by the formula of Friedewald et al. Apolipoprotein B (apo B) and AI (apo AI) concentration were determined by immunoturbidimetric method using specific controls. SCAP genotype was determined by PCR and MslI enzyme digestion. The study protocol was approved by the Joint Commission on Ethics of the Turku University and the Turku University Central Hospital. Each subject gave written informed consent. Data analysis was based on analysis of variance. Values shown are mean standard deviation. Discontinuous variables were analysed by using the -test. GG genotype subjects were combined with GA heterozygotes for statistical analysis, as the number of subjects with GG genotype was small. The SCAP genotype and treatment groups were used as independent factors in analysis of vari-

The hepatic lipase gene C‐480T polymorphism in the development of early coronary atherosclerosis: the Helsinki Sudden Death Study

Background  The T allele of the hepatic lipase (HL) C‐480T polymorphism was previously found to be associated with lower post‐heparin plasma HL activity, atherosclerosis and risk of coronary artery disease. We studied the association of HL C‐480T polymorphism with the extent of atherosclerosis at vessel‐wall level in an autopsy series of middle‐aged men.

Leucine 7 to proline 7 polymorphism in the neuropeptide Y gene and changes in serum lipids during a family-based counselling intervention among school-aged children with a family history of CVD.

OBJECTIVE To compare whether serum lipids and their changes during a health education intervention are associated with the Leu7Pro polymorphism in the signal peptide part of neuropeptide Y (NPY) in children with normal weight and in those with overweight. DESIGN An intervention study. SETTING A family-based intervention of risk factors for prevention of CHD in Finland. SUBJECTS Subjects were 443 children with a family history of CVD participating in family-based health education. The children were divided into two groups according to NPY genotype: children with Leu7/Pro7 or Pro7/Pro7 genotype (n 50) and children with Leu7/Leu7 genotype (n 393). The final sample of the follow-up study included 353 (80 %) children (Pro7 allele carriers, n 43; Leu7/Leu7, n 310). RESULTS At baseline, the Leu7Pro polymorphism was not associated with serum lipid values after adjustment for body weight in boys or girls. There was a significant interaction of NPY genotype group by time and body weight (P = 0.043 for three-way interaction: time x NPY genotype x body weight) in LDL-cholesterol (LDL-C) concentration among boys. LDL-C decreased among boys with normal weight in both NPY groups and in overweight boys with the Leu7/Leu7 genotype, whereas it increased in overweight boys with the Pro7 allele. Two-way interaction (time x NPY genotype) showed no significant differences in changes of serum lipids between the NPY genotype groups among boys or girls. CONCLUSIONS The Leu7Pro polymorphism may be associated with dietary response to LDL-C concentration in overweight boys with a family history of early-onset CVD.

Hepatic lipase C-480T polymorphism modifies the effect of HDL cholesterol on the risk of acute myocardial infarction in men: a prospective population based study

Previous studies have revealed an inverse association between high density lipoprotein cholesterol (HDL-C) levels and the risk of acute myocardial infarction (AMI).1,2 HDL-C level is modulated by genetic factors as well as environmental factors such as obesity, smoking, and physical exercise. Hepatic lipase (HL) is a lipolytic enzyme in lipoprotein metabolism, functioning as a phospholipase, an acylglycerol hydrolase, and a ligand of cell surface glycosaminoglycans, hydrolysing triglyceride-rich lipoprotein particles.3 Recently, it has been reported that HL is synthesised by macrophages.4 The HL gene variation has a significant effect on the variability of HDL-C in the population.5,6 The functional HL promoter C-480T transition, also referred to as (-514C/T), leads to three common genotypes: CC, CT, and TT. The C and T alleles are associated with high and low HL activity, respectively.7–9 However, the common polymorphisms of HL (-480T), cholesterol ester transfer protein (CETP) (TaqIB), lipoprotein lipase (S447X), and lecithin cholesterol acyl transferase (S208T) contribute only about 2.5% to the variance of HDL-C in the population.10 This suggests that the HL C-480T polymorphism and HDL-C levels are different factors, and studying their interaction is justified. One previous study has shown that there might be an interaction between CETP gene polymorphism and HDL-C on the risk of myocardial infarction.11 This result raises the possibility that other polymorphisms associated with HDL-C—for example, HL gene polymorphism—might interact with HDL-C and thus modify the risk of AMI. In fact, an effect of the C-480T polymorphism on coronary artery disease (CAD) has been sought in several studies with both negative7,12 and positive findings.13–15 One possible reason for the mixed results may be the interaction between HL C-480T genotype and HDL levels on CAD, a hypothesis not studied previously. To address this question, and …

Upstream Transcription Factor 1 (USF1) allelic variants regulate lipoprotein metabolism in women and USF1 expression in atherosclerotic plaque

Upstream transcription factor 1 (USF1) allelic variants significantly influence future risk of cardiovascular disease and overall mortality in females. We investigated sex-specific effects of USF1 gene allelic variants on serum indices of lipoprotein metabolism, early markers of asymptomatic atherosclerosis and their changes during six years of follow-up. In addition, we investigated the cis-regulatory role of these USF1 variants in artery wall tissues in Caucasians. In the Cardiovascular Risk in Young Finns Study, 1,608 participants (56% women, aged 31.9 ± 4.9) with lipids and cIMT data were included. For functional study, whole genome mRNA expression profiling was performed in 91 histologically classified atherosclerotic samples. In females, serum total, LDL cholesterol and apoB levels increased gradually according to USF1 rs2516839 genotypes TT < CT < CC and rs1556259 AA < AG < GG as well as according to USF1 H3 (GCCCGG) copy number 0 < 1 < 2. Furthermore, the carriers of minor alleles of rs2516839 (C) and rs1556259 (G) of USF1 gene had decreased USF1 expression in atherosclerotic plaques (P = 0.028 and 0.08, respectively) as compared to non-carriers. The genetic variation in USF1 influence USF1 transcript expression in advanced atherosclerosis and regulates levels and metabolism of circulating apoB and apoB-containing lipoprotein particles in sex-dependent manner, but is not a major determinant of early markers of atherosclerosis.

Expression of sterol regulatory element-binding transcription factor (SREBF) 2 and SREBF cleavage-activating protein (SCAP) in human atheroma and the association of their allelic variants with sudden cardiac death

BackgroundDisturbed cellular cholesterol homeostasis may lead to accumulation of cholesterol in human atheroma plaques. Cellular cholesterol homeostasis is controlled by the sterol regulatory element-binding transcription factor 2 (SREBF-2) and the SREBF cleavage-activating protein (SCAP). We investigated whole genome expression in a series of human atherosclerotic samples from different vascular territories and studied whether the non-synonymous coding variants in the interacting domains of two genes, SREBF-2 1784G>C (rs2228314) and SCAP 2386A>G, are related to the progression of coronary atherosclerosis and the risk of pre-hospital sudden cardiac death (SCD).MethodsWhole genome expression profiling was completed in twenty vascular samples from carotid, aortic and femoral atherosclerotic plaques and six control samples from internal mammary arteries. Three hundred sudden pre-hospital deaths of middle-aged (33–69 years) Caucasian Finnish men were subjected to detailed autopsy in the Helsinki Sudden Death Study. Coronary narrowing and areas of coronary wall covered with fatty streaks or fibrotic, calcified or complicated lesions were measured and related to the SREBF-2 and SCAP genotypes.ResultsWhole genome expression profiling showed a significant (p = 0.02) down-regulation of SREBF-2 in atherosclerotic carotid plaques (types IV-V), but not in the aorta or femoral arteries (p = NS for both), as compared with the histologically confirmed non-atherosclerotic tissues. In logistic regression analysis, a significant interaction between the SREBF-2 1784G>C and the SCAP 2386A>G genotype was observed on the risk of SCD (p = 0.046). Men with the SREBF-2 C allele and the SCAP G allele had a significantly increased risk of SCD (OR 2.68, 95% CI 1.07–6.71), compared to SCAP AA homologous subjects carrying the SREBF-2 C allele. Furthermore, similar trends for having complicated lesions and for the occurrence of thrombosis were found, although the results were not statistically significant.ConclusionThe results suggest that the allelic variants (SREBF-2 1784G>C and SCAP 2386A>G) in the cholesterol homeostasis regulating SREBF-SCAP pathway may contribute to SCD in early middle-aged men.