The contribution of candidate genes to the response of plasma lipids and lipoproteins to dietary challenge

The Association of Dietary Cholesterol from Egg Consumption on Cardiovascular Diseases Risk Varies from Person to Person

The public and scientists remain skeptical about egg consumption, given that cardiovascular diseases (CVDs) are the leading causes of death in worldwide. This review mainly explained the recurrence of contradictory conclusions about relationships between egg consumption and CVD risk and discussed effects of egg cholesterol intake on cholesterol homeostasis. Factors including individual health status and cholesterol sensitivity, dietary pattern, region, and race should be distinguished when understanding generalized conclusions. Identified compensatory mechanisms in response to dietary cholesterol and the resulting balance in cholesterol biosynthesis, absorption, and efflux supported the view that moderate egg consumption had no substantial overall impacts on cholesterol homeostasis in healthy people. Excessive cholesterol intake is not recommended in individuals with distempered metabolism. More than cholesterol metabolism, impacts of egg consumption as a part of overall diet on CVD risk should be considered from aspects of nutrient intake, lipid metabolism, and energy supply in the future.

Macronutrient intake modulates impact of EcoRI polymorphism of ApoB gene on lipid profile and inflammatory markers in patients with type 2 diabetes

We sought to examine whether dietary intakes may affect the relationship between ApoB EcoRI and lipid profile, as well as serum inflammatory markers, in patients with type 2 diabetes (T2DM). This current study consisted of 648 diabetic patients. Dietary intake was calculated by a food frequency questionnaire. Biochemical markers (high-density lipoprotein (HDL), total cholesterol (TC), LDL, TG, CRP, IL-18, PGF2α) were measured based on standard protocols. Genotyping of the Apo-B polymorphisms (rs1042031) was conducted by the PCR–RFLP method. The gene-diet interactions were evaluated using GLMs. In comparison to GG homozygotes, A-allele carriers with above the median -CHO intake (≥ 54 percent of total energy) had considerably greater TC and PGF2a concentrations. Furthermore, as compared to GG homozygotes, A-allele carriers with above the median protein intake (≥ 14 percent of total energy) had higher serum levels of TG (P = 0.001), CRP (P = 0.02), TG/HDL (P = 0.005), and LDL/HDL (P = 0.04) ratios. Moreover, A-allele carriers with above the median total fat intake (≥ 35 percent of total calories) had significantly higher TC level (P = 0.04) and LDL/HDL (P = 0.04) ratios compared to GG homozygotes. Furthermore, when compared to GG homozygotes, A-allele carriers who consumed above the median cholesterol (> 196 mg) had greater TG (P = 0.04), TG/HDL (P = 0.01) ratio, and IL-18 (P = 0.02). Furthermore, diabetic patients with the GA, AA genotype who consume above the median cholesterol had lower ghrelin levels (P = 0.01). In terms of LDL/HDL ratio, ApoB EcoRI and dietary intakes of specific fatty acids (≥ 9 percent for SFA and ≥ 12 percent for MUFA) had significant interaction. LDL/HDL ratio is greater in A-allele carriers with above the median SFA intake (P = 0.04), also when they consumed above the median MUFA this association was inverse (P = 0.04). Our study showed that plasma lipid levels in participants carrying the (AA or AG) genotype were found to be more responsive to increasing the percentage of energy derived from dietary fat, CHO, protein, SFA, and cholesterol consumption. Therefore, patients with a higher genetic susceptibility (AA or AG) seemed to have greater metabolic markers with a higher percentage of macronutrient consumption. Also, ApoB EcoRI correlations with metabolic markers might be attenuated with above the median MUFA consumption.

A Nutrigenetic Update on CETP Gene–Diet Interactions on Lipid-Related Outcomes

Purpose of Review

An abnormal lipid profile is considered a main risk factor for cardiovascular diseases and evidence suggests that single nucleotide polymorphisms (SNPs) in the cholesteryl ester transfer protein (CETP) gene contribute to variations in lipid levels in response to dietary intake. The objective of this review was to identify and discuss nutrigenetic studies assessing the interactions between CETP SNPs and dietary factors on blood lipids.

Recent Findings

Relevant articles were obtained through a literature search of PubMed and Google Scholar through to July 2021. An article was included if it examined an interaction between CETP SNPs and dietary factors on blood lipids. From 49 eligible nutrigenetic studies, 27 studies reported significant interactions between 8 CETP SNPs and 17 dietary factors on blood lipids in 18 ethnicities. The discrepancies in the study findings could be attributed to genetic heterogeneity, and differences in sample size, study design, lifestyle and measurement of dietary intake. The most extensively studied ethnicities were those of Caucasian populations and majority of the studies reported an interaction with dietary fat intake. The rs708272 (TaqIB) was the most widely studied CETP SNP, where ‘B1’ allele was associated with higher CETP activity, resulting in lower high-density lipoprotein cholesterol and higher serum triglycerides under the influence of high dietary fat intake.

Summary

Overall, the findings suggest that CETP SNPs might alter blood lipid profiles by modifying responses to diet, but further large studies in multiple ethnic groups are warranted to identify individuals at risk of adverse lipid response to diet.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11883-022-00987-y.

Genetic susceptibility, dietary cholesterol intake, and plasma cholesterol levels in a Chinese population

Accompanied with nutrition transition, non-HDL-C levels of individuals in Asian countries has increased rapidly, which has caused the global epicenter of nonoptimal cholesterol to shift from Western countries to Asian countries. Thus, it is critical to underline major genetic and dietary determinants. In the current study of 2,330 Chinese individuals, genetic risk scores (GRSs) were calculated for total cholesterol (TC; GRS_TC, 57 SNPs), LDL-C (GRS_LDL-C, 45 SNPs), and HDL-C (GRS_HDL-C, 65 SNPs) based on SNPs from the Global Lipid Genetics Consortium study. Cholesterol intake was estimated by a 74-item food-frequency questionnaire. Associations of dietary cholesterol intake with plasma TC and LDL-C strengthened across quartiles of the GRS_TC (effect sizes: -0.29, 0.34, 2.45, and 6.47; P _interaction = 0.002) and GRS_LDL-C (effect sizes: -1.35, 0.17, 5.45, and 6.07; P _interaction = 0.001), respectively. Similar interactions with non-HDL-C were observed between dietary cholesterol and GRS_TC (P _interaction = 0.001) and GRS_LDL-C (P _interaction = 0.004). The adverse effects of GRS_TC on TC (effect sizes across dietary cholesterol quartiles: 0.51, 0.82, 1.21, and 1.31; P _interaction = 0.023) and GRS_LDL-C on LDL-C (effect sizes across dietary cholesterol quartiles: 0.66, 0.52, 1.12, and 1.56; P _interaction = 0.020) were more profound in those having higher cholesterol intake compared with those with lower intake. Our findings suggest significant interactions between genetic susceptibility and dietary cholesterol intake on plasma cholesterol profiles in a Chinese population.

The interaction of cholesteryl ester transfer protein gene variations and diet on changes in serum lipid profiles

BACKGROUND/OBJECTIVES

Gene-diet interactions may have an important role in the disparities between the lipid responses of individuals to diet. This study aimed to investigate whether polymorphisms (rs5882 and rs3764261) in the cholesteryl ester transfer protein (CETP) gene modify the association of diet with changes in serum lipid profiles.

SUBJECTS/METHODS

A total of 4700 individuals aged ≥18 years were selected from among participants of the Tehran Lipid and Glucose Study. After 3.6 years of follow-up, changes in serum lipid profiles were evaluated. Usual dietary intake was assessed using a validated food frequency questionnaire. DNA samples were genotyped with HumanOmniExpress-24-v1-0 bead chips (containing 649,932 SNP loci).

RESULTS

No significant interaction was found between CETP polymorphisms and dietary patterns in changing lipid profiles. Mean changes of total cholesterol (TC) decreased in higher quartiles of fish intake in A allele carriers (Q1:8.02, Q4:5.58, P_trend = 0.01) compared to the CC genotype (Q1:3.65, Q4:8.93, P_trend = 0.11) (P_i = 0.02). There are ascending trends of changes in triglyceride (TG) concentrations across quartiles of total fat, monounsaturated and saturated fat consumption in G allele carriers of rs5882 compared to the AA genotype. There was a declining trend for mean changes in TG concentrations across quartiles of carbohydrate intake in G allele carriers of rs5882 compared to the AA genotype (P_i = 0.01).

CONCLUSIONS

Our data demonstrated that minor allele carriers of rs5882 had a better TG value than AA homozygote individuals when consuming a low fat and high carbohydrate diet. Fish intake modifies the association of rs3764261with TC concentrations.

Cholesteryl ester transfer protein gene variations and macronutrient intakes interaction in relation to metabolic syndrome: Tehran lipid and glucose study

Objective(s):

There are controversial results regarding the effect of the interaction of CETP polymorphisms with dietary fats on the lipid profiles. The aim of this study was to examine the effect of CETP polymorphisms (rs5882 and rs3764261) and macronutrient intakes interaction in relation to metabolic syndrome (MetS) or its components.

Materials and Methods:

In this nested case-control study, subjects were selected from among participants of the Tehran Lipid and Glucose Study. Cases (n=441) were individually matched with two controls (844 non-MetS subjects). DNA samples were genotyped with HumanOmniExpress-24-v1-0 bead chips, including 649,932 SNP loci.

Results:

The mean ages at baseline were 38.1±10 and 37.0±10 years in women and 36.2±11 and 36.3±11 years in men, respectively in cases and controls. We did not find significant gene-diet interactions between rs5882 and dietary macronutrient intakes in relation to MetS risk. The risk of low HDL-C was lower in the first quartile of MUFA and total fat intake in G allele carriers, compared to AA genotype group. The risk of high BP appeared to increase significantly in higher quartiles of trans-fatty acid intakes (>1.81% of total energy intake) in G allele carriers compared with the AA genotype group. No significant interactions were found between rs3764261 and macronutrient intakes in association with MetS or its components.

Conclusion:

Our findings demonstrate that dietary fats modify the association of rs5882 and risk of low HDL-C and high blood pressure.

Effects of a 6-month caloric restriction induced-weight loss program in obese postmenopausal women with and without the metabolic syndrome: a MONET study

OBJECTIVE

To compare the effects of a caloric restriction (CR) on body composition, lipid profile, and glucose homeostasis in obese postmenopausal women with and without metabolic syndrome (MetS).

METHODS

Secondary analyses were performed on 73 inactive obese postmenopausal women (age 57.7 ± 4.8 years; body mass index 32.4 ± 4.6 kg/m) who participated in the 6-month CR arm of a study of the Montreal-Ottawa New Emerging Team. The harmonized MetS definition was used to categorize participants with MetS (n = 20, 27.39%) and without MetS (n = 53, 72.61%). Variables of interest were: body composition (dual-energy X-ray absorptiometry), body fat distribution (computed tomography scan), glucose homeostasis at fasting state and during a euglycemic/hyperinsulinemic clamp, fasting lipids, and resting blood pressure.

RESULTS

By design, the MetS group had a worse cardiometabolic profile, whereas both groups were comparable for age. Fifty-five participants out of 73 displayed no change in MetS status after the intervention. Twelve participants out of 20 (or 60.0%) in the MetS group had no more MetS after weight loss (P = NS), whereas 6 participants out of 53 (or 11.3%) in the other group developed the MetS after the intervention (P = NS). Overall, indices of body composition and body fat distribution improved significantly and similarly in both groups (P between 0.03 and 0.0001). Furthermore, with the exception of triglyceride levels and triglycerides/high-density lipoprotein cholesterol ratio, which decrease significantly more in the MetS group (P ≤ 0.05), no difference was observed between groups for the other variables of the cardiometabolic profile.

CONCLUSIONS

Despite no overall significant effects on MetS, heteregeneous results were obtained in response to weight loss in the present study, with some improving the MetS, whereas other displaying deteriorations. Further studies are needed to identify factors and phenotypes associated with positive and negative cardiometabolic responses to CR intervention.

Genetic variations of cholesteryl ester transfer protein and diet interactions in relation to lipid profiles and coronary heart disease: a systematic review

Data on diet–genotype interactions in the prevention or treatment of dyslipidemia have increased remarkably. This systematic review aimed to assess nutrigenetic studies regarding the modulating effect of diet on cholesteryl ester transfer protein (CETP) polymorphisms in relation to metabolic traits.

Data were collected through studies published between 2000 and SEP. 2016 using five electronic databases. The quality of eligible studies was assessed using a 12-item quality checklist, derived from the STrengthening the REporting of Genetic Association Studies (STREGA) statement. CETP variants that had associations with lipid profiles in previous studies were extracted for drawing of the linkage disequilibrium (LD) plot.

Among CETP variants, the rs9989419 best represented this genome wide association signal across all populations, based on LD r² estimates from 1000 genomes references. In the 23 found eligible studies (clinical trials and observational), the TaqIB and I405V polymorphisms were the two most intensively studied. Two studies reported the effect of interaction between rs3764261 and diet on lipid levels. Regarding the rs708272 (Taq1B), individuals with the B1 risk allele showed better responses to dietary interventions than those with B2B2 genotype, whereas with I405V, inconsistent results have been reported. Modest alcohol consumption was associated with decreased risk of coronary heart disease among B2 carriers of rs708272.

It is concluded that variations in the CETP gene may modulate the effects of dietary components on metabolic traits. These results have been controversial, indicating complex polygenic factors in metabolic response to diet and lack of uniformity in the study conditions and designs.

Dietary cholesterol and cardiovascular disease: a systematic review and meta-analysis

BACKGROUND

Dietary cholesterol has been suggested to increase the risk of cardiovascular disease (CVD), which has led to US recommendations to reduce cholesterol intake.

OBJECTIVE

The authors examine the effects of dietary cholesterol on CVD risk in healthy adults by using systematic review and meta-analysis.

DESIGN

MEDLINE, Cochrane Central, and Commonwealth Agricultural Bureau Abstracts databases were searched through December 2013 for prospective studies that quantified dietary cholesterol. Investigators independently screened citations and verified extracted data on study and participant characteristics, outcomes, and quality. Random-effect models meta-analysis was used when at least 3 studies reported the same CVD outcome.

RESULTS

Forty studies (17 cohorts in 19 publications with 361,923 subjects and 19 trials in 21 publications with 632 subjects) published between 1979 and 2013 were eligible for review. Dietary cholesterol was not statistically significantly associated with any coronary artery disease (4 cohorts; no summary RR), ischemic stroke (4 cohorts; summary RR: 1.13; 95% CI: 0.99, 1.28), or hemorrhagic stroke (3 cohorts; summary RR: 1.09; 95% CI: 0.79, 1.50). Dietary cholesterol statistically significantly increased both serum total cholesterol (17 trials; net change: 11.2 mg/dL; 95% CI: 6.4, 15.9) and low-density lipoprotein (LDL) cholesterol (14 trials; net change: 6.7 mg/dL; 95% CI: 1.7, 11.7 mg/dL). Increases in LDL cholesterol were no longer statistically significant when intervention doses exceeded 900 mg/d. Dietary cholesterol also statistically significantly increased serum high-density lipoprotein cholesterol (13 trials; net change: 3.2 mg/dL; 95% CI: 0.9, 9.7 mg/dL) and the LDL to high-density lipoprotein ratio (5 trials; net change: 0.2; 95% CI: 0.0, 0.3). Dietary cholesterol did not statistically significantly change serum triglycerides or very-low-density lipoprotein concentrations.

CONCLUSION

Reviewed studies were heterogeneous and lacked the methodologic rigor to draw any conclusions regarding the effects of dietary cholesterol on CVD risk. Carefully adjusted and well-conducted cohort studies would be useful to identify the relative effects of dietary cholesterol on CVD risk.

Nutritional genomics for the characterization of the effect of bioactive molecules in lipid metabolism and related pathways

Cardiovascular disease and cancer are the main causes of morbidity and mortality worldwide. Thus, investigators have focused their efforts on gaining insight into understanding the mechanisms involved in the development and evolution of these diseases. In the past decade, and with the contribution of the -omics technologies, strong evidence has supported an essential role of gene-nutrient interactions in these processes, pointing at natural bioactive molecules as promising complementary agents that are useful in preventing or mitigating these diseases. In addition, alterations in lipid metabolism have recently gained strong interest since they have been described as a common event required for the progression of both diseases. In the present review, we give an overview of lipid metabolism, mainly focusing on lipoprotein metabolism and the mechanisms controlling lipid homeostasis. In addition, we review the modulation of lipid metabolism by bioactive molecules, highlighting their potential use as therapeutic agents in preventing, and treating chronic diseases such as cardiovascular disease and cancer. Finally, we report the usefulness of the -omics technologies in nutritional research, focusing on recent findings, within nutritional genomics, in the interaction of bioactive components from foods with several genes that are involved in the development and progression of these diseases.

Risk of gestational diabetes mellitus in relation to maternal egg and cholesterol intake

Higher egg and cholesterol intakes are associated with increased risk of type 2 diabetes mellitus. However, their association with gestational diabetes mellitus (GDM) has not been evaluated. The authors assessed such associations in both a prospective cohort study (1996-2008; 3,158 participants) and a case-control study (1998-2002; 185 cases, 411 controls). A food frequency questionnaire was used to assess maternal diet. Multivariable models were used to derive relative risks and 95% confidence intervals. Compared with no egg consumption, adjusted relative risks for GDM were 0.94, 1.01, 1.12, 1.54, and 2.52 for consumption of ≤1, 2-3, 4-6, 7-9, and ≥10 eggs/week, respectively (P for trend=0.008). Women with high egg consumption (≥7/week) had a 1.77-fold increased risk compared with women with lower consumption (95% confidence interval (CI): 1.19, 2.63). The relative risk for the highest quartile of cholesterol intake (≥294 mg/day) versus the lowest (<151 mg/day) was 2.35 (95% CI: 1.35, 4.09). In the case-control study, the adjusted odds ratio for consuming ≥7 eggs/week versus <7 eggs/week was 2.65 (95% CI: 1.48, 4.72), and the odds of GDM increased with increasing cholesterol intake (P for trend=0.021). In conclusion, high egg and cholesterol intakes before and during pregnancy are associated with increased risk of GDM.

Apolipoprotein E polymorphism and the characteristics of diseased vessels in male Chinese patients with angiographic coronary artery disease: a case-case study

BACKGROUND

Variations in the apolipoprotein E (apo E) gene may predict the incidence of coronary artery disease (CAD). However, the correlation between apo E polymorphism and the severity of CAD is still unclear.

HYPOTHESIS

Apolipoprotein E polymorphism can predict CAD.

METHODS

Used a case-case study of 213 Chinese angiographically-defined CAD patients who were screened for apo E genotypes. The characteristics of their diseased vessels were recorded.

RESULTS

Apolipoprotein E4 carriers had > 75% stenosis, more wide-ranging and longer vessel disease, a greater number of diseased vessels, and a higher Gensini score than apo E2 carriers or individuals with the apo E3/3 genotype. Apolipoprotein E2 carriers had < or =75% stenosis and a shorter length of vessel disease than individuals with the apo E3/3 genotype or apo E4 carriers. The severity of stenosis, length of vessel disease, and number of diseased vessels were affected by the interaction between genotype and body mass index, family history of CAD, total plasma cholesterol level, smoking history, and hypertension history.

CONCLUSION

The apo E4 allele may serve as an independent genetic marker predicting severity of CAD. Other CAD risk factors may accelerate the process of pathogenesis. The apo E2 allele may play a protective role.

The influence of nutrigenetics on the lipid profile: interaction between genes and dietary habits

Nutrigenetics is a new field with few studies in Latin America. Our aim is to investigate the way in which different genes related to the lipid profile influence the response to specific dietary habits. Eight polymorphisms on seven genes were investigated in a sample (n = 567) from Porto Alegre, RS, Brazil. All the volunteers completed a food diary that was then assessed and classified into nine food groups. A number of nutrigenetic interactions were detected primarily related to the apolipoprotein E (apoE) gene. For example, frequent consumption of foods rich in polyunsaturated fat resulted in the beneficial effect of increasing HDL-C only in individuals who were not carriers of the E*4 allele of the APOE gene, whereas variations in eating habits of E*4 carriers did not affect their HDL-C (P = 0.018). Our data demonstrate for the first time nutrigenetic interactions in a Brazilian population.

Seven lipoprotein lipase gene polymorphisms, lipid fractions, and coronary disease: a HuGE association review and meta-analysis

Lipoprotein lipase (LPL) is a key enzyme in lipoprotein metabolism and a major candidate gene for coronary heart disease (CHD). The authors assessed associations between 7 LPL polymorphisms and lipid fractions and CHD risk in population-based cohort, case-control, and cross-sectional studies published by January 2007. Meta-analyses of 22,734 CHD cases and 50,177 controls in 89 association studies focused on the relations of the T-93G (rs1800590), D9N (rs1801177), G188E, N291S (rs268), PvuII (rs285), HindIII (rs320), and S447X (rs328) polymorphisms to high density lipoprotein cholesterol, triglycerides, myocardial infarction, or coronary stenosis. Carriers of 9N or 291S had modestly adverse lipid profiles. Carriers of the less common allele of HindIII or of 447X had modestly advantageous profiles. The combined odds ratio for CHD among carriers was 1.33 (95% confidence interval (CI): 1.14, 1.56) for 9N, 1.07 (95% CI: 0.96, 1.20) for 291S, 0.89 (95% CI: 0.81, 0.98) for the less common HindIII allele, and 0.84 (95% CI: 0.75, 0.94) for 447X. For T-93G (odds ratio (OR) = 1.22, 95% CI: 0.98, 1.52) and PvuII (OR = 0.96, 95% CI: 0.89, 1.04), there were null associations with lipid levels or CHD risk; information on G188E was limited (OR = 2.80, 95% CI: 0.88, 8.87). The study of LPL genotypes confirms the existence of close interrelations between high density lipoprotein cholesterol and triglyceride pathways. The influence of these genotypes on CHD risk warrants further investigation.

Older Elite Football Players Have Reduced Cardiac and Osteoporosis Risk Factors

INTRODUCTION/PURPOSE

Aging with a sedentary lifestyle is associated with increased risk for developing cardiovascular disease (CVD), osteoporosis, and sarcopenia. The purpose of this study was to determine whether former professional football athleticism would be associated with reduced risk factors for CVD and osteoporosis, and higher muscle mass in later life.

METHODS

Maximal aerobic capacity (VO2max), body composition, and lipid and glucose risk factors for CVD were compared between 16 older former professional football players and never-athletic men matched for age, body mass index, current physical activity, and race. Regional bone mineral density of the football players was compared with age-matched reference norms.

RESULTS

Despite greater physical activity into middle age, the former football players had similar VO2max as the controls. Former football players had 26% lower total-body fat mass, 26% lower visceral adipose tissue area, and 13% higher muscle mass compared with the controls (P < 0.05). High-density lipoprotein cholesterol (HDL-C) levels were 37% higher (P < 0.001), HDL2-C levels were fourfold higher (P < 0.001), and triglycerides were 31% lower (P < 0.05) in the former football players than the controls. The former football players also had 20% and 6% higher total-body bone mineral content and density than the controls (P < 0.05) and higher lumbar spine, femoral neck, and greater trochanter bone mineral density than similar age-referenced norms (P < 0.05).

CONCLUSION

Elite athlete physical activity status in young adulthood, and remaining physically active in middle age, may confer body composition changes that are sustained in older adulthood. In this small sample of older men, former successful professional athletes who remained physically active in middle age have a favorable body composition and reduced risk factors for CVD and osteoporosis compared with healthy age- and BMI-matched older men.

A systematic review and meta-analysis of the relationship between lipoprotein lipase Asn291Ser variant and diseases

This systematic review attempted to summarize the associations between the Asn291Ser variant in the lipoprotein lipase (LPL) gene and dyslipidemia, the risk of type 2 diabetes mellitus (T2DM), and coronary heart disease (CHD). In addition, the relationships between the Asn291Ser variant and other metabolic diseases such as obesity and high blood pressure were also investigated in this systematic review. We systematically reviewed the literature by means of a meta-analysis. Twenty-one articles, including 19,246 white subjects, were selected for this meta-analysis. The summary standardized mean difference (SMD) of plasma triglyceride (TG) for carriers compared with noncarriers of the Asn291Ser variant was 3.23 (P < 0.00001). The summary SMD of plasma HDL-cholsterol (HDL-C) for carriers compared with noncarriers of the Asn291Ser variant was -3.42 (P < 0.0001). The summary SMD of the association of the Asn291Ser variant with plasma TG increased with increasing age and weight gain. Significant interactions between the LPL Asn291Ser variant and fasting glucose, T2DM, and CHD were seen (P = 0.02, 0.04, and 0.01, respectively). No significant interactions were seen between the LPL Asn291Ser variant and body mass index, waist-hip ratio, and blood pressure (P > 0.05). This meta-analysis indicates that the Asn291Ser variant in the LPL gene is a risk factor for dyslipidemia, characterized by hypertriglyceridemia and low HDL-C levels. And the Asn291Ser variant in the LPL gene predisposes to more severe dyslipidemia with increasing age and weight gain. Also, this meta-analysis shows that the LPL Asn291Ser variant is associated with CHD and T2DM.

Variation in the cholesteryl ester transfer protein (CETP) gene does not influence individual plasma cholesterol response to changes in the nature of dietary fat

BACKGROUND AND AIMS

Some individuals respond to a greater extent than others to changes in dietary fat and cholesterol even when dietary intake is consistent. A prospective study has been undertaken in which two groups of individuals according to cholesteryl ester transfer protein (CETP) genotype were compared in terms of plasma lipid response to altering the nature of dietary fat in a free-living situation.

METHODS AND RESULTS

Following genotyping, 35 individuals with the CETP Taq1 B1B1 genotype were paired with age and sex-matched individuals with one or two CETP B2 alleles, to undertake a single crossover trial with a diet high in saturated fat and a diet high in polyunsaturated fat. There was no washout period between the two 4-week phases. Plasma lipoproteins were measured at the beginning and end of each phase. The difference (95% CI) in plasma LDL-cholesterol concentration at the end of the PUFA and SAFA diets was 0.95 (0.71, 1.19) mmol/l in the CETP B1B1 group and 0.80 (0.57, 1.04) mmol/l in the group with at least one CETP B2 allele. The dietary induced changes in the two genotype groups were not significantly different (p=0.38) from each other. Comparable results were observed for plasma total cholesterol. The high PUFA and SAFA diets did not significantly alter plasma HDL concentration in either of the CETP genotype groups. Response was also similar according to apolipoprotein E genotype (E3E3 vs E4+) and lipoprotein lipase genotype (S447X).

CONCLUSIONS

The results of this study do not support previous studies in which CETP genotype predicted plasma LDL-cholesterol response to diet. CETP genotype does not significantly affect the change in plasma total and LDL-cholesterol concentrations that occur when altering the nature of dietary fat. These data suggest that the influence of genetic factors on total and LDL-cholesterol may be relatively small in comparison with the effect of dietary manipulation.

Exploration of multilocus effects in a highly polymorphic gene, the apolipoprotein (APOB) gene, in relation to plasma apoB levels

A detailed exploration of all the polymorphisms in candidate genes is required to better characterize the relationship between gene variability and complex traits. We propose a novel strategy for investigating the association between a highly polymorphic gene and a phenotype, by combining a multilocus genotype analysis and an haplotype analysis. For the multilocus genotype analysis, a data mining tool--termed DICE (Detection of Informative Combined Effects)--was developed to identify the best subset of polymorphisms that are associated--individually or in combination--with the phenotype. For the haplotype analysis, we used our recently developed method of haplotype-phenotype association to determine the most informative and parsimonious haplotype model fitting the data. We illustrate this strategy by investigating the association between twelve polymorphisms of the APOB gene and plasma apoB levels in 1442 European subjects. After exploring all main effects and interactions between polymorphisms, DICE identified the N4311S polymorphism as the most informative polymorphism in relation to apoB levels. Haplotype analysis led to the same conclusion. Additionally, DICE identified the E4154K (EcoRI) and the T2488T (XbaI) polymorphisms as potentially interesting. This selection was not modified by inclusion of the common APOE polymorphism in the analysis.

Linkage and linkage disequilibrium analysis of the lipoprotein lipase gene with lipid profiles in Chinese hypertensive families

Elevated TG [triacylglycerol (triglyceride)] is a significant independent risk factor for cardiovascular disease. LPL (lipoprotein lipase) is one of the key enzymes in the metabolism of the TG-rich lipoproteins which hydrolyses TG from the chylomicrons and very-LDL (low-density lipoprotein). To investigate the relationship between the LPL gene and lipid profiles, especially TG, in 148 hypertensive families, we have chosen seven flanking microsatellite markers and four internal markers of the LPL gene and conducted linkage analysis by SOLAR and S.A.G.E. (statistical analysis for genetic epidemiology)/SIBPAL 2 programs, and linkage disequilibrium analysis by QTDT (quantitative transmission/disequilibrium test) and GOLD (graphical overview of linkage disequilibrium). There were statistically significant differences in lipid levels between subjects without and with hypertension within families. A maximum LOD score of 1.3 with TG at the marker D8S261 was observed by SOLAR. Using S.A.G.E./SIBPAL 2, we identified a linkage with TG at the marker 'ATTT' located within intron 6 of the LPL gene (P=0.0095). Two SNPs (single nucleotide polymorphisms), HindIII and HinfI, were found in linkage disequilibrium with LDL-cholesterol levels (P=0.0178 and P=0.0088 respectively). A strong linkage disequilibrium was observed between the HindIII in intron 8 and HinfI in the exon 9 (P<0.00001, D'=0.895). Linkage disequilibrium was also found between the 'ATTT' polymorphism in intron 6 and two SNPs (P=0.0021 and D'=0.611 for HindIII; and P=0.00004, D'=0.459 for HinfI). The present study in the Chinese families with hypertension suggested that the LPL gene might influence lipid levels, especially TG metabolism. Replication studies both in Chinese and other populations are warranted to confirm these results.

Lipid transfer proteins (LTP) and atherosclerosis

This review deals with four lipid transfer proteins (LTP): three are involved in cholesteryl ester (CE) synthesis or transport, the fourth deals with plasma phospholipid (PL) transfer. Experimental models of atherosclerosis, clinical and epidemiological studies provided information as to the relationship of these LTP(s) to atherosclerosis, which is the main focus of this review. Thus, inhibition of acyl-CoA:cholesterol acyltransferase (ACAT) 1 and 2 decreases cholesterol absorption, plasma cholesterol and aortic cholesterol esterification in the aorta. The discovery that tamoxifen is a potent ACAT inhibitor explained the plasma cholesterol lowering of the drug. The use of ACAT inhibition in humans is under current investigation. As low cholesteryl ester transfer protein (CETP) activity is connected with high HDL-C, several CETP inhibitors were tried in rabbits, with variable results. A new CETP inhibitor, Torcetrapib, was tested in humans and there was a 50-100% increase in HDL-C. Lecithin cholesterol acyl-transferase (LCAT) influences oxidative stress, which can be lowered by transient LCAT gene transfer in LCAT-/- mice. Phospholipid transfer protein (PLTP) deficiency reduced apo B production in apo E-/- mice, as well as oxidative stress in four models of mouse atherosclerosis. In conclusion, the ability to increase HDL-C so markedly by inhibitors of CETP introduces us into a new era in prevention and treatment of coronary heart disease (CHD).

Missense mutation W86R in exon 3 of the lipoprotein lipase gene in a boy with chylomicronemia

BACKGROUND

Familial LPL deficiency is a rare inborn error of metabolism caused by mutational change within the LPL gene, which leads to massive hypertriglyceridemia.

METHODS

The underlying molecular defect in a boy of Croatian descent was studied by SSCP analysis, DNA sequencing and finally confirmed by RFLP.

RESULTS

DNA analysis showed the child to be a homozygote and his parents heterozygotes for TGG-->CGG change in codon 86 of the LPL gene, which leads to W86R amino acid substitution. DNA sequence analysis also showed a silent mutation in the third exon of father's DNA, V108V. Determination of some LPL gene polymorphisms showed the child and his parents to have HindIII/H+H+ and both S447 wild-type alleles, whereas for PvuII the parents had P(+)P- and the child P(+)P+ genotype.

CONCLUSIONS

In this case, W86R mutation was the reason for the production of nonfunctional enzyme and consequently triacylglycerol (TG) exceeding 15 mmol/l. This implies the risk of frequent episodes of acute pancreatitis. Decreased LPL activity leads to elevated triacylglycerol levels and reduced HDL-cholesterol, both risk factors for the development of coronary artery disease. LPL genotyping especially of young patients with hypertriglyceridemia is therefore necessary and justifiable.

Dietary cholesterol does not increase biomarkers for chronic disease in a pediatric population from northern Mexico

BACKGROUND

An increased incidence of coronary artery disease (CAD) is prevalent in northern Mexico. Effects of specific dietary components on risk factors for CAD have not been evaluated in children.

OBJECTIVE

The purpose was to evaluate the effects of dietary cholesterol provided by whole eggs on the lipoprotein profile, LDL size, and phenotype in children from this region.

DESIGN

Children (29 girls and 25 boys aged 8-12 y) were randomly assigned to either 2 eggs/d (EGG period; 518 additional mg cholesterol) or the equivalent amount of egg whites (SUB period; 0 additional mg cholesterol) for 30 d. After a 3-wk washout period, the children were assigned to the alternate treatment.

RESULTS

Subjects were classified as hyporesponders (no increase or </=0.05 mmol/L increase in plasma cholesterol for 100 mg additional cholesterol) or hyperresponders (>/=0.06 mmol/L increase). During the EGG period, the hyperresponders (n = 18) had an elevation in both LDL cholesterol (from 1.54 +/- 0.38 to 1.93 +/- 0.36 mmol/L) and HDL cholesterol (from 1.23 +/- 0.26 to 1.35 +/- 0.29 mmol/L) with no changes in LDL:HDL. In contrast, hyporesponders (n = 36) had no significant alterations in plasma LDL or HDL cholesterol. All subjects had an increase in LDL peak diameter during the EGG period (P < 0.01) and a decrease (P < 0.01) in the smaller LDL subfractions. In addition, 5 of the children having LDL phenotype B (15%) shifted from this high-risk pattern to pattern A after the EGG treatment.

CONCLUSIONS

Intake of 2 eggs/d results in the maintenance of LDL:HDL and in the generation of a less atherogenic LDL in this population of Mexican children.

CETP gene variation: relation to lipid parameters and cardiovascular risk

PURPOSE OF REVIEW

Over the past decade lowering of low-density lipoprotein-cholesterol levels has been established as the foundation for preventing coronary artery disease, but substantial additional risk reduction remains to be gained by modifying risk factors other than low-density lipoprotein-cholesterol. Raising high-density lipoprotein-cholesterol levels by inhibiting activity of the cholesteryl ester transfer protein (CETP) is a prime target. Research on naturally occurring variants in the CETP gene has yielded numerous insights that have been relevant for understanding lipoprotein metabolism, and crucial to the development of pharmacological CETP inhibition.

RECENT FINDINGS

This review discusses a number of recently published studies, including a haplotype analysis of the CETP promoter region confirming that the -629 C-->A variant, not the TaqIB variant, is instrumental in determining CETP activity, as previously suggested. In addition, we discuss a recent meta-analysis which confirms that the I405V and TaqIB variants are indeed associated with lower CETP activity and higher high-density lipoprotein-cholesterol levels. Also, we review two subanalyses of large randomized controlled pravastatin trials which found no evidence for a proposed pharmacogenetic interaction between the CETP TaqIB variant and pravastatin treatment.

SUMMARY

The currently available evidence suggests that several genetic variants in the CETP gene are associated with altered CETP plasma levels and activity, high-density lipoprotein-cholesterol plasma levels, low-density lipoprotein and high-density lipoprotein particle size, and perhaps the risk of coronary artery disease. No evidence exists for a pharmacogenetic interaction between the CETP TaqIB variant and pravastatin efficacy.

Haplotypes of the cholesteryl ester transfer protein gene predict lipid-modifying response to statin therapy

Cholesteryl ester transfer protein (CETP) plays a central role in high-density lipoprotein (HDL) metabolism. Single nucleotide polymorphisms (SNPs) and haplotypes in the CETP gene were determined in 98 patients with untreated dyslipidemias and analyzed for associations with plasma CETP and plasma lipids before and during statin treatment. Individual CETP SNPs and haplotypes were both significantly associated with CETP enzyme mass and activity. However, only certain CETP haplotypes, but not individual SNPs, significantly predicted the magnitude of change in HDL cholesterol (HDL-C) and triglycerides. After adjusting for covariates and multiple testing, the TTCAAA haplotype showed a gene-dose effect in predicting the HDL-C increase (P=0.03), while the TTCAAAGGG and AAAGGG haplotypes predicted a decrease in triglycerides (P=0.04 both). This is the first study to demonstrate that SNP haplotypes derived from allelic SNP combinations in the CETP gene were more informative than single SNPs in predicting the response to lipid-modifying therapy with statins.

Natural genetic variation as a tool in understanding the role of CETP in lipid levels and disease

Since the identification of cholesteryl ester transfer protein (CETP), its role in the modulation of HDL levels and cardiovascular disease has been debated. With the early detection of genetic variants followed by the finding of families deficient in CETP, genetic studies have played a large role in the attempts to understand the association of CETP with lipids and disease; however, results of these studies have often led to disparate conclusions. With the availability of a greater variety of genetic polymorphisms and larger studies in which disease has been examined, it is now possible to compare the breadth of CETP genetic studies and draw better conclusions. The most broadly studied polymorphism is TaqIB for which over 10,000 individuals have been genotyped and had HDL levels determined. When these studies are subjected to a meta-analysis, the B2B2 homozygotes are found to have higher HDL levels than B1B1 homozygotes (0.12 mmol/l, 95% CI = 0.11-0.13, P < 0.0001). A similar analysis of the I405V polymorphism yields 0.05 mmol/l higher HDL levels in 405VV homozygotes than in 405II homozygotes (95% CI = 0.03-0.07, P < 0.0001). The implications of these studies for cardiovascular disease will be addressed.

Genetic variation and the lipid response to dietary intervention: a systematic review

There is wide interindividual variation in the lipid and lipoprotein responses to dietary change, and the existence of consistent hypo- and hyperresponders supports the hypothesis that responsiveness is related to genetic variation. Many studies have investigated the possibility that the heterogeneity in responsiveness to changes in dietary fat, cholesterol, and fiber intake is explained by variation in genes whose products affect lipoprotein metabolism, eg, apolipoproteins, enzymes, and receptors. A systematic review of the literature was carried out to investigate the effect of genetic variation on the lipid response to dietary intervention. A search strategy for the MEDLINE database retrieved 2540 articles from 1966 to February 2002. This strategy was adapted and performed on the EMBASE database, which retrieved 2473 articles from 1980 to week 9, 2002. Reference lists from relevant journal articles were also checked. This is the first systematic review of the literature, and it summarizes results available from 74 relevant articles. There is evidence to suggest that variation in the genes for apolipoprotein (apo) A-I, apo A-IV, apo B, and apo E contributes to the heterogeneity in the lipid response to dietary intervention. However, the effects of genetic variation are not consistently seen and are sometimes conflicting. Future studies need to have much larger sample sizes based on power calculations and carefully controlled dietary interventions and should investigate the effects of polymorphisms in multiple genes instead of the effects of polymorphisms in single genes.

Men classified as hypo- or hyperresponders to dietary cholesterol feeding exhibit differences in lipoprotein metabolism

The purpose of this study was to evaluate the differences that occur within the plasma compartment of normolipidemic men, classified on the basis of their response to prolonged consumption of additional dietary cholesterol. Using a crossover design, 40 men aged 18-57 y were randomly allocated to an egg (640 mg/d additional dietary cholesterol) or placebo group (0 mg/d additional dietary cholesterol), for two 30-d periods, which were separated by a 3-wk washout period. Subjects were classified as hypo- [increase in plasma total cholesterol (TC) of <0.05 mmol/L for each additional 100 mg of dietary cholesterol consumed] or hyperresponders (increase in TC of > or =0.06 mmol/L for each additional 100 mg of dietary cholesterol consumed) on the basis of their plasma reaction to the additional dietary cholesterol provided. Male hyporesponders did not experience an increase in LDL cholesterol (LDL-C) or HDL cholesterol (HDL-C) during the egg period, whereas both lipoproteins were significantly (P < 0.0001 and P < 0.05, respectively) elevated in hyperresponders. Although the LDL/HDL ratio was increased in male hyperresponders after the high cholesterol period, the mean increase experienced by this population was still within National Cholesterol Education Program guidelines. Furthermore, male hyperresponders had higher lecithin cholesterol acyltransferase (P < 0.05) and cholesteryl ester transfer protein (P < 0.05) activities during the egg period, which suggests an increase in reverse cholesterol transport. These data suggest that additional dietary cholesterol does not increase the risk of developing an atherogenic lipoprotein profile in healthy men, regardless of their response classification.

Lipoprotein lipase gene polymorphisms in Croatian patients with coronary artery disease

Modifications in lipoprotein lipase levels lead to elevated triglycerides and reduced high density lipoprotein (HDL), both of which are risk factors for coronary artery disease (CAD). Hence, we examined the influence of the -93T/G, D9N, N291S, and S447X polymorphisms in the lipoprotein lipase (LPL) gene on CAD risk and lipid levels in Croatian patients with and without angiographically confirmed CAD. The N291S polymorphism was significantly associated with CAD (OR = 0.36; 95% CI = 0.13, 0.99; p = 0.048). This association was only moderately affected by adjusting for various lipids (OR = 0.36; 95% CI = 0.12, 1.08; p = 0.068). HDL2-cholesterol and apolipoprotein A-I levels were significantly higher in non-carriers of the -93T/G and D9N polymorphisms in the CAD group (p = 0.017 and 0.028, respectively). The N291S genetic variant did not show any significant difference between carriers and non-carriers in either group studied for any of the lipids. Lower triglyceride and higher HDL2-cholesterol levels in the control group were associated with carriers of the S447X mutation (p = 0.043 and 0.056, respectively). LPL gene polymorphisms might be involved in predisposition to CAD and determination of lipid profiles.

Apolipoprotein E and diets: a case of gene-nutrient interaction?

Apolipoprotein E has key functions in lipoprotein metabolism, and polymorphisms in the apolipoprotein E gene are associated with distinct lipoprotein patterns. The possibility of gene-nutrient interactions for apolipoprotein E has been addressed in many studies. Although results have generally been mixed, the indications for such an interaction have been more common in studies employing a metabolic challenge. Studies directly designed to examine apolipoprotein E gene-nutrient interactions are needed.

Nutritional influences on lipids and future atherosclerosis beginning prenatally and during childhood

Autopsy findings of pre-atherosclerotic changes in the coronaries and other arteries of young soldiers killed in action in the Korean war stimulated studies on the mechanisms that regulate the development of atherosclerosis. The data confirmed that vascular changes obviously begin developing much earlier than the manifestation of clinical symptoms, and numerous risk factors for atherosclerosis have been firmly identified. The mechanisms consist of the effects of numerous poorly characterized genes and a complex mixture of environmental factors, dominated by factors associated with nutrition. Observational and epidemiological studies also showed that the pathogenesis is not restricted to the postnatal period. The nutrition of the fetus during the 40 weeks of pregnancy may also play an important role both directly and by determining metabolism in the individual more widely than was previously believed. At the same time, several studies suggested that biochemical predictors of atherosclerosis, e.g. a high concentration of serum LDL cholesterol, a low concentration of serum HDL cholesterol and other lipid and lipoprotein abnormalities, may already in early infancy and childhood predict values later in life quite well. We now review recent studies that deal with the effects of fetal and childhood nutrition on serum lipid values, and discuss the likelihood that clinically meaningful changes of atherosclerosis may appear earlier than expected.

Gene-diet interaction and plasma lipid response to dietary intervention

Research in the field of gene-diet interactions as determinants of plasma lipid response to dietary interventions has accumulated a substantial body of evidence during the past decade. Several candidate genes have shown some promise as potential markers of individual dietary responsiveness. Among the best characterized are the APOE, APOA4, APOB, APOC3, and LPL loci. Other genes are being continuously incorporated to this most interesting search. However, in very few cases has consensus been achieved about the usefulness of genetic markers as clinically significant predictors of dietary response. The increased ability to generate genotypic information, in combination with the knowledge from the human genome project and more comprehensive experimental designs, will dramatically improve our capacity to answer many of our current questions. It will also help to prove that knowledge of an individual's genetic background will facilitate more precise dietary counseling and intervention, and more efficacious primary and secondary coronary heart disease prevention.