Tobacco smoking, estrogen receptor alpha gene variation and small low density lipoprotein level

Lipoprotein Metabolism, Dyslipidemia, and Lipid-Lowering Therapy in Women: A Comprehensive Review

Lipid-lowering therapy (LLT) is a cornerstone of atherosclerotic cardiovascular disease prevention. Although LLT might lead to different reductions in low-density lipoprotein cholesterol (LDL-C) levels in women and men, LLT diminishes cardiovascular risk equally effectively in both sexes. Despite similar LLT efficacy, the use of high-intensity statins, ezetimibe, and proprotein convertase subtilisin/kexin type 9 inhibitors is lower in women compared to men. Women achieve the guideline-recommended LDL-C levels less often than men. Greater cholesterol burden is particularly prominent in women with familial hypercholesterolemia. In clinical practice, women and men with dyslipidemia present with different cardiovascular risk profiles and disease manifestations. The concentrations of LDL-C, lipoprotein(a), and other blood lipids differ between women and men over a lifetime. Dissimilar levels of LLT target molecules partially result from sex-specific hormonal and genetic determinants of lipoprotein metabolism. Hence, to evaluate a potential need for sex-specific LLT, this comprehensive review (i) describes the impact of sex on lipoprotein metabolism and lipid profile, (ii) highlights sex differences in cardiovascular risk among patients with dyslipidemia, (iii) presents recent, up-to-date clinical trial and real-world data on LLT efficacy and safety in women, and (iv) discusses the diverse medical needs of women and men with dyslipidemia and increased cardiovascular risk.

Healthy lifestyle, plasma metabolites, and risk of cardiovascular disease among individuals with diabetes

BACKGROUND AND AIMS

Lifestyle management is a fundamental aspect of diabetes care to prevent cardiovascular disease (CVD); however, the underlying metabolic mechanism is not well established. We aimed to identify metabolites associated with different lifestyle factors, and estimate their mediating roles between lifestyle and CVD risk among people with diabetes.

METHODS

Lifestyle and metabolomic data were available for 5072 participants with diabetes who were free of CVD at baseline in the UK Biobank. The healthy level of 5 lifestyle factors was defined as non-central obesity, non-current smoking, moderate alcohol intake, physically active, and healthy diet. A total of 44 biomarkers across 7 metabolic pathways including lipoprotein particles, fatty acids, amino acids, fluid balance, inflammation, ketone bodies, and glycolysis were quantified by nuclear magnetic resonance (NMR) spectroscopy.

RESULTS

All 44 assayed metabolites were significantly associated with at least one lifestyle factor. Approximately half of metabolites, which were mostly lipoprotein particles and fatty acids, showed a mediating effect between at least one lifestyle factor and CVD risk. NMR metabolites jointly mediated 43.4%, 30.0%, 16.8%, 43.4%, and 65.5% of the association of non-central obesity, non-current smoking, moderate alcohol intake, physically active, and healthy diet with lower CVD risk, respectively. In general, though metabolites that significantly associated with lifestyle were mostly different across the 5 lifestyle factors, the pattern of association was consistent between fatty acids and all 5 lifestyle factors. Further, fatty acids showed significant mediating effects in the association between all 5 lifestyle factors and CVD risk with mediation proportion ranging from 12.2% to 26.8%.

CONCLUSIONS

There were large-scale differences in circulating NMR metabolites between individuals with diabetes who adhered to a healthy lifestyle and those did not. Differences in metabolites, especial fatty acids, could partially explain the association between adherence to multiple healthy lifestyle and lower CVD risk among people with diabetes.

Prevalence of dyslipidemia and associated risk factors among newly diagnosed Type-2 Diabetes Mellitus (T2DM) patients in Kushtia, Bangladesh

Dyslipidemia is considered a significant modifiable risk factor for type-2 diabetes mellitus (T2DM) and has become one of the emerging health problems throughout the world. In Bangladesh, data on dyslipidemia among newly diagnosed T2DM patients are comparatively inadequate. This study aimed to evaluate the prevalence of dyslipidemia and its associated risk factors in newly diagnosed T2DM patients. This cross-sectional study was conducted by a well-structured questionnaire from 132 newly diagnosed type-2 diabetic patients attending the Mujibur Rahman Memorial Diabetic Hospital in Kushtia, Bangladesh. Data regarding socio-demographic, anthropometric, fasting blood glucose, total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) were collected from all the respondents. The association between dyslipidemia and its associated factors was analyzed using the multivariate logit regression model. The findings suggest that the prevalence rate of dyslipidemia was 75.7% in female and 72.6% in male T2DM patients. The odds of having dyslipidemia were 1.74 (95% Cl: 1.58-1.87) times significantly higher in female (p<0.001). The other factors associated with dyslipidemia encompassed age between 30-39 years (OR: 2.32, 95% CI: 1.97-2.69), obesity (OR: 2.63, 95% CI: 2.27-2.90), waist circumferences of male ≥90 and female ≥80 (OR: 1.65, 95% CI: 1.59-1.89), hypertensive patients (OR: 1.51, 95% CI: 1.45-1.74), physically inactive (OR: 3.25, 95% CI: 1.84-4.68), and current smoker or tobacco user (OR: 1.93, 95% CI: 1.85-2.13). This study concluded that the high prevalence of dyslipidemia was found among newly diagnosed type-2 diabetes patients and associated with gender, age, BMI, waist circumference, poor physical activity, and smoking, or tobacco use. This result will support increase awareness of dyslipidemia and its associated risk factors among type-2 diabetes patients.

Evaluating the prevalence, awareness, and control of hypertension, diabetes, and dyslipidemia in Korea using the NHIS-NSC database: A cross-sectional analysis

This study aimed to evaluate the prevalence, awareness, and control of hypertension, diabetes, and dyslipidemia in Korea according to sex and age, and to identify factors that were associated with the prevalence, awareness, and control of these cardiovascular risk factors among middle-aged Koreans.A cross-sectional analysis was conducted using 2013 data from the National Health Insurance Service-National Sample Cohort (NHIS-NSC) database. A total of 136,755 individuals were considered eligible based on no history of stroke or heart disease, age of 40 to 64 years at the examination, and completion of health examinations. Data regarding demographic factors and cardiovascular risk factors had been obtained using questionnaires, physical examinations, and blood tests.Hypertension was the most prevalent condition among middle-aged Koreans (25.76%), followed by dyslipidemia (16.58%) and diabetes (10.22%). Among these three conditions, dyslipidemia was associated with the lowest awareness rates (24.14%). Hypertension and diabetes were more prevalent among men than among women, although the prevalence of dyslipidemia was higher among women > 50 years old. The prevalence of hypertension and diabetes increased with advancing age among men and women, although the prevalence of dyslipidemia decreased with age among men (highest prevalence: 50.59% among men aged between 40 and 44 years). Among Korean men (relative to women), the odds ratios were 1.50 for hypertension, 1.96 for diabetes, and 0.82 for dyslipidemia. Age, central obesity, and body mass index were significantly associated with the development of all 3 conditions.There are sex- and age-specific patterns in the prevalence, awareness, and control of hypertension, diabetes, and dyslipidemia in Korea. Dyslipidemia is becoming increasingly common although most middle-aged Koreans are not aware of this condition leading to low control rate. These results may help identify population subgroups at a high risk of hypertension, diabetes, and dyslipidemia, and may guide the management of cardiovascular disease in Korea.

Empirically derived subtypes of serious emotional disturbance in a large adolescent sample

PURPOSE

The heterogeneity of serious emotional disturbance has been thoroughly documented among adolescents with nationally representative data derived from structured interviews, although use of these interviews may not be feasible within the context of brief and self-administered school surveys. This study seeks to identify distinct subtypes of serious emotional disturbance in a large school-based sample.

METHODS

A total of 108,736 students fully completed the K6 scale that was included on the 2012 Kentucky Incentives for Prevention Survey. Latent class analysis was used to derive subtypes of serious emotional disturbance among students receiving a positive screen (n = 15,147). To determine significant predictors of class membership, adjusted rate ratios and 95 % confidence intervals were calculated using multinomial logistic regression.

RESULTS

A four-class model was the most parsimonious, with four distinct subtypes emerging that varied by both symptom type and severity: comorbid moderate severity, comorbid high severity, anxious moderate severity, and depressed high severity. Age, gender, race/ethnicity, family structure, substance use, antisocial behavior, role impairments, and peer victimization were significant predictors of class membership, although the magnitude of these effects was stronger for the two high severity groups.

CONCLUSIONS

Our results suggest heterogeneity of serious emotional disturbance by both symptom type and severity. Prevention programs may benefit by shifting focus from specific disorders to the core features of serious emotional disturbance, including psychological distress, high comorbidity, and role impairments.

Associations between smoking, components of metabolic syndrome and lipoprotein particle size

BACKGROUND

The clustering of metabolic and cardiovascular risk factors is known as metabolic syndrome (MetS). The risk of having MetS is strongly associated with increased adiposity and can be further modified by smoking behavior. Apolipoproteins (apo) associated with low-density lipoprotein-cholesterol (LDL-C) and high-density lipoprotein-cholesterol (HDL-C) may be altered in MetS. This study aimed to examine the association between smoking and the following parameters: MetS and its components, levels of apolipoproteins and estimated lipoprotein particle size, separately for men and women, and in different body mass index (BMI) classes.

METHODS

We included 24,389 men and 35,078 women aged between 18 and 80 years who participated in the LifeLines Cohort Study between December 2006 and January 2012; 5,685 men and 6,989 women were current smokers. Participants were categorized into three different body mass index (BMI) classes (BMI <25; BMI 25 to 30; BMI ≥30 kg/m²). MetS was defined according to the National Cholesterol Education Program's Adult Treatment Panel III (NCEP:ATPIII) criteria. Blood pressure, anthropometric and lipid measurements were rigorously standardized, and the large sample size enabled a powerful estimate of quantitative changes. The association between smoking and the individual MetS components, and apoA1 and apoB, was tested with linear regression. Logistic regression was used to examine the effect of smoking and daily tobacco smoked on risk of having MetS. All models were age adjusted and stratified by sex and BMI class.

RESULTS

Prevalence of MetS increased with higher BMI levels. A total of 64% of obese men and 42% of obese women had MetS. Current smoking was associated with a higher risk of MetS in both sexes and all BMI classes (odds ratio 1.7 to 2.4 for men, 1.8 to 2.3 for women, all P values <0.001). Current smokers had lower levels of HDL cholesterol and apoA1, higher levels of triglycerides and apoB, and higher waist circumference than non-smokers (all P <0.001). Smoking had no consistent association with blood pressure or fasting blood glucose. In all BMI classes, we found a dose-dependent association of daily tobacco consumption with MetS prevalence as well as with lower levels of HDL cholesterol, higher triglyceride levels and lower ratios of HDL cholesterol/apoA1 and, only in those with BMI <30, LDL cholesterol/apoB (all P <0.001).

CONCLUSIONS

Smoking is associated with an increased prevalence of MetS, independent of sex and BMI class. This increased risk is mainly related to lower HDL cholesterol, and higher triglycerides and waist circumference. In addition, smoking was associated with unfavorable changes in apoA1 and apoB, and in lipoprotein particle size. Please see related commentary: http://www.biomedcentral.com/1741-7015/11/196.

Evidence of sex differences in the relationship between current tobacco use and past-year serious psychological distress: 2005-2008 National Survey on Drug Use and Health

PURPOSE

Cigarette use is highly prevalent in psychiatric populations. Studies suggest that smokeless tobacco use is not significantly associated with past-year psychiatric morbidity, with evidence that tobacco use differ among sexes. The relationships between current tobacco use and past-year serious psychological distress, major depressive episode and anxiety disorder were therefore examined. Sex differences in the aforementioned relationship were also examined.

METHODS

A total of 133,221 adults from four successive independent samples of the 2005-2008 National Survey on Drug Use and Health were included. Prevalence odds ratios and 95 % confidence intervals were calculated using multivariable logistic regression adjusting for demographic factors, survey year, pregnancy (women only), past-year medical morbidity, past-year psychiatric comorbidity, and past-year substance use disorders.

RESULTS

No associations were demonstrated among smokeless tobacco users. Statistically significant sex differences were found for current tobacco use and serious psychological distress (p < 0.001). Both male and female smokers were significantly more likely to have serious psychological distress and anxiety disorder compared to never users, while only female smokers were more likely to have major depressive episode. The strongest associations were found for anxiety disorder among all adults as well as both sexes.

CONCLUSIONS

The null associations for both sexes for smokeless tobacco may support a reduced risk profile. Female cigarette smokers may be more vulnerable to subclinical distress and depression than males. Studies using other nationally representative samples are needed to confirm these data.

Mixed modeling of meta-analysis P-values (MixMAP) suggests multiple novel gene loci for low density lipoprotein cholesterol

Informing missing heritability for complex disease will likely require leveraging information across multiple SNPs within a gene region simultaneously to characterize gene and locus-level contributions to disease phenotypes. To this aim, we introduce a novel strategy, termed Mixed modeling of Meta-Analysis P-values (MixMAP), that draws on a principled statistical modeling framework and the vast array of summary data now available from genetic association studies, to test formally for locus level association. The primary inputs to this approach are: (a) single SNP level p-values for tests of association; and (b) the mapping of SNPs to genomic regions. The output of MixMAP is comprised of locus level estimates and tests of association. In application of MixMAP to summary data from the Global Lipids Gene Consortium, we suggest twelve new loci (PKN, FN1, UGT1A1, PPARG, DMDGH, PPARD, CDK6, VPS13B, GAD2, GAB2, APOH and NPC1) for low-density lipoprotein cholesterol (LDL-C), a causal risk factor for cardiovascular disease and we also demonstrate the potential utility of MixMAP in small data settings. Overall, MixMAP offers novel and complementary information as compared to SNP-based analysis approaches and is straightforward to implement with existing open-source statistical software tools.

Gender differences in the association between smoking and dyslipidemia: 2005 Korean National Health and Nutrition Examination Survey

BACKGROUND

Smoking has been reported to be associated with abnormal lipid metabolism. However, it remains uncertain whether adverse metabolic effects of smoking on dyslipidemia differ with gender. The objective of this study was to investigate the association between smoking and dyslipidemia in men and women.

METHODS

We analyzed data from 2166 men and 3003 women aged ≥20 years assessed in the Third Korea National Health and Nutrition Examination Survey (2005). Dyslipidemia was defined according to the National Cholesterol Education Program-Adult Treatment Panel III.

RESULTS

The prevalence of dyslipidemia was higher in men than in women. The odds ratios (95% confidence interval) of dyslipidemia associated with current smoking were 1.35 (0.98-1.85) in men and 1.92 (1.19-3.10) in women (p for interaction with gender <0.001). After stratification by components of dyslipidemia, women smokers showed higher odds ratios of having high triglyceride and low high-density lipoprotein cholesterol than men smokers. The association between current heavy-smoking (≥20 pack-years) and dyslipidemia was stronger in women than in men.

CONCLUSIONS

The association between smoking and dyslipidemia was significantly different between men and women. Women smokers might be more susceptible to develop dyslipidemia than men smokers.

Estrogen receptor polymorphisms and the vascular effects of hormone therapy

OBJECTIVE

To test whether estrogen receptor polymorphisms modify the effects of postmenopausal hormone therapy on biomarkers and on risk of coronary heart disease events, stroke, or venous thromboembolism.

METHODS AND RESULTS

The design was a nested case-control study in the Women's Health Initiative trials of postmenopausal hormone therapy. The study included all cases in the first 4 years: 359 cases of coronary heart disease, 248 of stroke, and 217 of venous thromboembolism. Six estrogen receptor-α polymorphisms and 1 estrogen receptor-β polymorphism were genotyped; 8 biomarkers known to be affected by hormone therapy were measured at baseline and 1 year after randomization. The polymorphisms were not associated with risk of vascular events and did not modify the increased risks of coronary heart disease, stroke, or venous thromboembolism due to hormone therapy. However, a reduced response of plasmin-antiplasmin to hormone therapy was noted for estrogen receptor-1 IVS1 (intron number 1)-354 (interaction P<0.0001, corrected for multiple comparisons P=0.014) and estrogen receptor-1 IVS1-1415 (interaction P<0.0001, corrected P=0.014).

CONCLUSIONS

Estrogen receptor polymorphisms reduce the effect of postmenopausal hormone therapy on plasmin-antiplasmin, a marker of coagulation and fibrinolysis. However, screening for estrogen receptor polymorphisms to identify women at less risk of adverse cardiovascular outcomes is not likely to be useful in making decisions about hormone therapy treatment.

Associations among smoking status, lifestyle and lipoprotein subclasses

BACKGROUND

The relationship between cigarette smoking and cardiovascular disease is well established, yet the underlying mechanisms remain unclear. Although smokers have a more atherogenic lipid profile, this may be mediated by other lifestyle-related factors. Analysis of lipoprotein subclasses by the use of nuclear magnetic resonance spectroscopy (NMR) may improve characterisation of lipoprotein abnormalities.

OBJECTIVE

We used NMR spectroscopy to investigate the relationships between smoking status, lifestyle-related risk factors, and lipoproteins in a contemporary cohort.

METHODS

A total of 612 participants (360 women) aged 40-69 years at baseline (1990-1994) enrolled in the Melbourne Collaborative Cohort Study had plasma lipoproteins measured with NMR. Data were analysed separately by sex.

RESULTS

After adjusting for lifestyle-related risk factors, including alcohol and dietary intake, physical activity, and weight, mean total low-density lipoprotein (LDL) particle concentration was greater for female smokers than nonsmokers. Both medium- and small-LDL particle concentrations contributed to this difference. Total high-density lipoprotein (HDL) and large-HDL particle concentrations were lower for female smokers than nonsmokers. The proportion with low HDL particle number was greater for female smokers than nonsmokers. For men, there were few smoking-related differences in lipoprotein measures.

CONCLUSION

Female smokers have a more atherogenic lipoprotein profile than nonsmokers. This difference is independent of other lifestyle-related risk factors. Lipoprotein profiles did not differ greatly between male smokers and nonsmokers.

The -351A/G polymorphism of ESR1 is associated with risk of myocardial infarction but not with extreme longevity

BACKGROUND

Women live longer than men. Some possible reasons for this advantage are the protection provided by high concentrations of 17β-estradiol (E2) during the premenopausal period and polymorphic variants of the estrogen receptors (ERs), which mediate various cardiovascular functions of E2.

METHODS

We tested whether the -351A/G and -397T/C polymorphisms of the ERα-encoding ESR1 were associated with extreme longevity. The genomic DNA of 148 centenarians (C), 414 young controls (Y), and 208 myocardial infarction patients (MI) was analyzed by RFLP-PCR.

RESULTS

Both polymorphisms were equally distributed in the Y, C, and in centenarians never diagnosed with MI (HC). In centenarians, none of these polymorphisms was associated with a particular lipid profile. The AA genotype of the -351A/G polymorphism was less frequent in the C, HC and Y groups than in MI patients (p=0.058, p=0.021, and p=0.004, respectively). In MI patients, the GG genotype of the -351A/G polymorphism was associated with significantly lower mean total cholesterol, LDL, and HDL levels compared to the AG (p=0.0194, p=0.0213, and p=0.0367, respectively) and AA genotypes (p=0.0014, p=0.0078, and p=0.0448, respectively).

CONCLUSIONS

The -351A/G ESR1 polymorphism might be associated with MI, but not with extreme longevity.

Association of polymorphisms in estrogen and thyroid hormone receptors with thyroid cancer risk

The receptors for thyroid hormone (THR) and oestrogen (ESR) are prototypes of nuclear transcription factors that regulate the expression of target genes. Genetic alterations in the genes of these receptors were found to be involved in cancer development. In this study we investigated the association of one SNP (rs2228480, T594T) and one microsatellite marker (D6S440) within the ESR1 gene and a dinucleotide repeat (D17S2189) within the THRA gene, with thyroid cancer risk. A case-control association study was conducted with 299 healthy individuals and 106 patients with thyroid cancer. Genotypic and allelic frequencies for the dinucleotide repeat in the ESR1 gene were similar between thyroid cancer patients and controls. For the AC repeat in the THRA gene, a slightly significant difference was found for the genotype 18/20 between the two groups (P = 0.034), which suggests that alleles with less than 20 repeats might have a protective effect in thyroid cancer risk. For the SNP T594T, the A allele was much more prevalent in patients than in controls and was highly associated with the risk of thyroid cancer (OR: 4,56; IC: 3.23-6.44; P < 10(-18)) and seems to have an additive mode of action. In conclusion, our data suggest that the SNP T594T but not the D6S440 and D17S189 is associated with thyroid cancer risk.

Estrogen receptor 1 gene polymorphisms in premenopausal women: interaction between genotype and smoking on lipid levels

Estrogen has multiple effects on lipid and lipoprotein metabolism. We investigated the association between the four common single nucleotide polymorphisms in the estrogen receptor 1 (ESR1) gene locus, -1989T>G, +261G>C, IVS1-397T>C and IVS1-351A>G, and lipid and lipoprotein levels in southern Brazilians. The sample consisted in 150 men and 187 premenopausal women. The women were considered premenopausal if they had regular menstrual bleeding within the previous 3 months and were 18-50 years of age. Exclusion criteria were pregnancy, secondary hyperlipidemia due to renal, hepatic or thyroid disease, and diabetes. Smoking status was self-reported; subjects were classified as never smoked and current smokers. DNA was amplified by PCR and was subsequently digested with the appropriate restriction enzymes. Statistical analysis was carried out for men and women separately. In the study population, major allele frequencies were _1989*T (0.83), +261*G (0.96), IVS1-397*T (0.58), and IVS1-351*A (0.65). Multiple linear regression analyses indicated that an interaction between +261G>C polymorphism and smoking was a significant factor affecting high-density lipoprotein cholesterol (HDL-C) levels (P = 0.028) in women. Nonsmoking women with genotype G/C of +261G>C polymorphism had mean HDL-C levels higher than those with G/G genotype (1.40 +/- 0.33 vs 1.22 +/- 0.26 mmol/L; P = 0.033). No significant associations with lipid and lipoprotein levels in women and men were detected for other polymorphisms. In conclusion, the +261G>C polymorphism might influence lipoprotein and lipid levels in premenopausal women, but these effects seem to be modulated by smoking, whereas in men ESR1 polymorphisms were not associated with high lipoprotein levels.

Association of ER-alpha gene polymorphism with metabolic phenotypes in Chinese Hans

Recently, two polymorphisms (rs1884052 and rs3778099) of estrogen receptor alpha (ER-alpha) gene were identified as being associated with primary quantitative bone mineral density (BMD) in a genome-wide association (GWA) study in Framingham cohorts. In this study we aimed at investigating the association of rs1884052 and rs3778099, and another polymorphism (rs2234693) located at intron 1 of the ER-alpha gene with BMD, body mass index (BMI), glucose, triglyceride, and total cholesterol (CHO) levels in Chinese Hans. We recruited 425 consecutive adult volunteers who had a physical examination in the Jinan Maternity and Child Care Hospital. We did not observe significant association of rs1884052 and rs3778099 with BMD, BMI, glucose, triglyceride, and total cholesterol (CHO) levels. For rs2234693, increased levels of BMD for hip, spine or whole-body regions were consistently observed in TT/TC genotype carriers than in CC genotype carriers, although the board line significance diminished after adjusting for age and gender. However, significant association of rs2234693 with glucose and CHO levels were observed in our sample. Subjects with TC/CC genotypes were associated with an increased level of glucose (p = 0.013) and CHO (p = 0.032) levels than subjects with TT genotypes. In conclusion, we did not confirm the association of rs1884052 and rs3778099 with BMD originally discovered in a GWA study; however, we made novel discoveries that rs2234693 was associated with glucose and CHO levels in Chinese Hans.

Association between arterial stiffness and variations in oestrogen-related genes

Increased arterial stiffness and wave reflection have been identified as cardiovascular disease risk factors. In light of significant sex differences and the moderate heritability of vascular function measures, we hypothesized that variation in the genes coding for estrogen receptors alpha (ESR1) and beta (ESR2) and aromatase (CYP19A1) is associated with aortic stiffness and pressure wave reflection as measured by noninvasive arterial tonometry. 1261 unrelated Framingham Offspring Study participants who attended the 7^th examination cycle (mean age 62±10 years, 52% women) and had arterial tonometry and genotyping data were included in the study. ANCOVA was used to assess the association of polymorphisms with forward wave amplitude, augmented pressure, augmentation index, carotid-femoral pulse wave velocity, and mean arterial pressure with adjustment for potential confounders. In the sex-pooled analysis, those homozygous for the minor allele at any of four ESR1 variants that were in strong linkage disequilibrium ((TA)_n, rs2077647, rs2234693 and rs9340799) had on average 18% higher augmented pressure and 16% greater augmentation index compared to carriers of one or two major alleles (p=0.0002–0.01). A similar magnitude of association was detected in those homozygous for the common allele at two ESR2 SNPs (p=0.007–0.02). Our results are consistent with the hypothesis that variation in ESR1 and ESR2, but not CYP19A1, is associated with increased wave reflection, which may contribute to previously demonstrated associations between these variants and adverse clinical events. Our findings will need to be replicated in additional cohorts.

Variation in estrogen-related genes associated with cardiovascular phenotypes and circulating estradiol, testosterone, and dehydroepiandrosterone sulfate levels

BACKGROUND

Younger age at the onset of menopause and lower circulating levels of estrogen are risk factors for cardiovascular disease. Several studies have detected associations between variations in genes encoding estrogen receptors alpha (ESR1) and beta (ESR2), and enzyme aromatase (CYP19A1), which regulates the estrogen to testosterone ratio, and cardiovascular phenotypes in the Framingham Heart Study. To explore potential mechanisms by which these gene variants may contribute to cardiovascular disease, we tested the hypothesis that the polymorphisms were associated with endogenous steroid hormone levels.

METHODS

Multiple regression analysis was used to assess the relation between reported polymorphisms and total serum estradiol, testosterone, and dehydroepiandrosterone sulfate levels in 834 men and 687 women who attended the third and fourth Framingham Heart Study examination cycles.

RESULTS

In men, significant associations were detected between CYP19A1 polymorphisms and estradiol and testosterone levels, and the estradiol to testosterone ratio (P ranges 0.0005-0.01). Specifically, carriers of common haplotype rs700518[G]-(TTTA)(n) [L]-rs726547[C] had higher estradiol levels (5% per copy; P = 0.0004), lower testosterone levels (17% per copy; P = 0.036), and a higher estradiol to testosterone ratio (24% per copy; P < 0.0001) compared with the rs700518[A]-(TTTA)(n) [S]-rs726547[C] carriers. In addition, postmenopausal carriers of the ESR2 (CA)(n) long allele and rs1256031 [C] allele had moderately higher estradiol levels (P < or = 0.03). No significant associations with the ESR1 variants were detected.

CONCLUSIONS

Our findings suggest that variations in CYP19A1 correlate with steroid hormone levels in men. Knowledge that a specific carrier status may predispose to altered steroid hormone levels may lead to targeted intervention strategies to reduce health risks in genetically susceptible individuals.

Association between lipid profile and circulating concentrations of estrogens in young men

OBJECTIVES

Men show higher rates of cardiovascular morbidity and mortality than pre-menopausal women and this sexual dimorphism may be related to sex-specific effects of sex steroids on cardiovascular risk factors. Unlike androgens, estrogens were not extensively investigated in relation to cardiovascular phenotypes in men.

METHODS

We examined associations of estradiol and estrone and their precursors (total testosterone and androstenedione) with traditional cardiovascular risk factors (lipids, blood pressure, body mass) in 933 young (median age: 19 years), apparently healthy Polish men.

RESULTS

Total estradiol was associated with total cholesterol (p=0.006) and high-density lipoprotein cholesterol (HDL-C) (p<0.001) and estrone showed the strongest associations with both total cholesterol (p<0.001) and low-density lipoprotein cholesterol (LDL-C) (p<0.001) in the unadjusted ANOVA analysis. In the multivariable adjusted models in which other independent variables were held as constant one standard deviation increase in estradiol level was associated with 6%-standard deviation increase in total cholesterol (standardized beta=0.06, p=0.038) and 6%-standard deviation decrease in HDL-cholesterol (standardized beta=-0.06, p=0.036). An increase in estrone levels by one standard deviation was associated with respective 12%- and 13%-standard deviation increases in total cholesterol (standardized beta=0.12, p<0.001) and LDL-cholesterol levels (standardized beta=0.12, p<0.001) after controlling for other predictors of lipids. Estrone correlated linearly with androstenedione (r=0.28, p<0.001) but there was no correlation between estradiol and testosterone. Estrogens retained their independent associations with lipids after adjustment for their biochemical precursors in the multivariable analysis.

CONCLUSIONS

Increased levels of estrogens are associated with unfavourable lipid profile in men and this association is present early in life, before apparent manifestations of cardiovascular disease.

ESR1 polymorphism is associated with plasma lipid and apolipoprotein levels in Caucasians of the Rochester Family Heart Study

We evaluated six estrogen receptor 1 (ESR1) polymorphisms for association with ten plasma lipid and apolipoprotein traits in 1,847 individuals (941 females and 906 males) in the multi-generation Rochester Family Heart Study using a generalized estimating equation approach. Apolipoprotein A-I (apoA-I), apoA-II, and HDL-cholesterol (HDL-C) were associated with exon 4 rs1801132 (Pro325Pro) genotype (P = 0.0044, P = 0.0048, and P = 0.0035, respectively). Positive correlation between levels of apoA-I, apoA-II, and HDL-C and the number of G alleles was observed in females (P = 0.0120, P = 0.0032, and P = 0.0030), but not males (P > 0.05). Because few studies have evaluated the effect of ESR1 gene polymorphisms on lipid traits in children, we also stratified our sample at the age of 15 years. There was evidence of association between intron 1 single-nucleotide polymorphisms rs9322331 and rs9340799 and apoC-II, and triglycerides (TGs) in youths 15 years and younger. In youths, evidence of association between rs9322331 and rs9340799 and apoC-II was stronger in males (P = 0.0036 and P = 0.0124) than in females (P > 0.05), whereas evidence of association with TG was stronger in females (P = 0.0030 and P = 0.0024) than in males (P > 0.05). These findings suggest that ESR1 variation plays an age- and sex-dependent role in determining plasma lipid and apolipoprotein levels.

Association of the estrogen receptor-alpha gene with the metabolic syndrome and its component traits in African-American families: the Insulin Resistance Atherosclerosis Family Study

OBJECTIVE

We previously detected an association between a region of the estrogen receptor-alpha (ESR1) gene and type 2 diabetes in an African-American case-control study; thus, we investigated this region for associations with the metabolic syndrome and its component traits in African-American families from the Insulin Resistance Atherosclerosis Family Study.

RESEARCH DESIGN AND METHODS

A total of 17 single nucleotide polymorphisms (SNPs) from a contiguous 41-kb intron 1-intron 2 region of the ESR1 gene were genotyped in 548 individuals from 42 African-American pedigrees. Generalized estimating equations were computed using a sandwich estimator of the variance and exchangeable correlation to account for familial correlation.

RESULTS

Significant associations were detected between ESR1 SNPs and the metabolic syndrome (P = 0.005 to P = 0.029), type 2 diabetes (P = 0.001), insulin sensitivity (P = 0.0005 to P = 0.023), fasting insulin (P = 0.022 to P = 0.033), triglycerides (P = 0.021), LDL (P = 0.016 to P = 0.034), cholesterol (P = 0.046), BMI (P = 0.016 to P = 0.035), waist circumference (P = 0.012 to P = 0.023), and subcutaneous adipose tissue area (P = 0.016).

CONCLUSIONS

It appears likely that ESR1 contributes to type 2 diabetes and CVD risk via pleiotropic effects, leading to insulin resistance, a poor lipid profile, and obesity.

Age-related changes in echocardiographic measurements: association with variation in the estrogen receptor-alpha gene

Left ventricular (LV) mass and other LV measures have been shown to be heritable. In this study we hypothesized that functional variation in the gene coding for estrogen receptor-alpha (ESR1), known for mediating the effect of estrogens on myocardium, is associated with age-related changes in LV structure. Four genetic markers (ESR1 TA repeat; rs2077647, or +30T>C; rs2234693, or PvuII; and rs9340799, or XbaI) were genotyped in 847 unrelated individuals (488 women) from the Framingham Offspring Study, who attended 2 examination cycles 16 years apart (mean ages at first examination: 43+/-9 years; at follow-up: 59+/-9 years). ANCOVA was used to assess the association of polymorphisms and their haplotypes with cross-sectional measurements and longitudinal changes in LV mass, wall thickness, end-diastolic and end-systolic internal diameter, and fractional shortening after adjustment for factors known to influence these variables. Changes over time were detected for all of the LV measurements (P ranging from <0.0001 to 0.02), except for fractional shortening in men. The SS genotype of the ESR1 TA repeat polymorphism in the promoter region was associated with longitudinal changes in LV mass and LV wall thickness (P ranging from 0.0006 to 0.01). Moreover, the TA[S]-+30[T]-PvuII[T]-XbaI[A] haplotype (frequency: 47.5%) was associated with greater LV changes as compared with the TA[L]-+30[C]-PvuII[C]-XbaI[G] haplotype (frequency: 31.8%). Our results are consistent with the hypothesis that common ESR1 polymorphisms are significantly associated with age-related changes in LV structure. Understanding the mechanisms predisposing to unfavorable LV remodeling of the heart with advancing age may aid in the discovery of new therapeutic targets for the prevention of heart failure.

Investigation of the estrogen receptor-alpha gene with type 2 diabetes and/or nephropathy in African-American and European-American populations

The estrogen receptor-alpha gene (ESR1) was selected as a positional candidate under a type 2 diabetes linkage peak at 6q24-27. A total of 42 ESR1 single nucleotide polymorphisms (SNPs) were genotyped in 380 African-American type 2 diabetic case subjects with end-stage renal disease (ESRD) and 276 African-American control subjects. A total of 22 ancestry informative markers were also genotyped, and the program Admixmap was used to adjust allelic and haplotypic association tests for individual estimates of admixture. The most significant association with type 2 diabetes-ESRD was with rs1033182 in intron 2 (P = 0.013, admixture-adjusted P(a) = 0.021). Genotyping 17 SNPs across a region of ESR1 intron 1-intron 2 in an expanded population of 851 case and 635 control subjects supported association with rs1033182 (P = 0.004, P(a) = 0.027) and with an independent six-SNP haplotype of high linkage disequilibrium spanning 6.4 kb (P < 0.0001, P(a) < 0.0001). The same 17 ESR1 SNPs were genotyped in 300 European-American type 2 diabetes-ESRD case subjects and 310 European-American control subjects. Two intron 2 SNPs, rs2431260 (P = 0.015) and rs1709183 (P = 0.019), and a four-SNP haplotype containing these SNPs (P = 0.033) were associated with type 2 diabetes and/or ESRD. Results suggest that intron 1 and intron 2 of the ESR1 gene may contain functionally important regions related to type 2 diabetes or ESRD risk.

Clinical importance and therapeutic modulation of small dense low-density lipoprotein particles

The National Cholesterol Education Programme Adult Treatment Panel III accepted the predominance of small dense low-density lipoprotein (sdLDL) as an emerging cardiovascular disease (CVD) risk factor. Most studies suggest that measuring low-density lipoprotein (LDL) particle size, sdLDL cholesterol content and LDL particle number provides additional assessment of CVD risk. Therapeutic modulation of small LDL size, number and distribution may decrease CVD risk; however, no definitive causal relationship is established, probably due to the close association between sdLDL and triglycerides and other risk factors (e.g., high-density lipoprotein, insulin resistance and diabetes). This review addresses the formation and measurement of sdLDL, as well as the relationship between sdLDL particles and CVD. The effect of hypolipidaemic (statins, fibrates and ezetimibe) and hypoglycaemic (glitazones) agents on LDL size and distribution is also discussed.

The association of oestrogen receptor alpha-haplotypes with cardiovascular risk factors in the British Women's Heart and Health Study

AIMS

One previous study among women with established coronary heart disease found a gene-treatment interaction between the oestrogen receptor gene (ESR1) and hormone replacement in their association with high density lipoprotein cholesterol (HDL-c). We aimed to replicate these findings in a general population sample.

METHODS AND RESULTS

Cross-sectional associations were assessed in a study of 3404 women from 23 towns across Britain who were aged 60-79 at the time of assessment and were described as white by the examining nurse. Women with the T-A haplotype [constructed from two single nucleotide polymorphisms (SNPs) in the first intron of ESR1: c454-397T > C (rs2234693) and c454-351A > G (rs9340799)], which was predicted to be associated with reduced oestrogen response, were more likely to have been past [per haplotype odds ratio 1.16 (95% CI 1.01, 1.33), P = 0.02] or to be current users [per haplotype odds ratio 1.19 (95% CI 0.99, 1.42), P = 0.05] of hormone replacement. However, there was no association between haplotype or either SNP and HDL-c or other cardiovascular disease risk factors and no statistical evidence of an interaction between hormone replacement use and haplotype or either SNP with respect to HDL-c or any other cardiovascular disease risk factors.

CONCLUSION

Women with the T-A haplotype are more likely to use hormone replacement. However, genotyping of ESR1 rs2234693 or rs9340799 in post-menopausal women to tailor hormone replacement is unlikely to markedly improve cardiovascular risk.