Novel gene-by-environment interactions: APOB and NPC1L1 variants affect the relationship between dietary and total plasma cholesterol

NPC1L1 Plays a Novel Role in Nonalcoholic Fatty Liver Disease

Niemann-Pick C1-Like 1 (NPC1L1) is a key protein in the transport of cholesterol, which exists in the brush marginal membrane of the intestinal epithelial cells and the timid duct membrane of the liver. It affects cholesterol absorption and plasma low-density lipoprotein levels. Cholesterol is both an important component of the cell membrane and a precursor of bile acid and steroid hormone synthesis. Abnormal cholesterol metabolism is closely related to nonalcoholic steatohepatitis (NASH). NASH can progress to fibrosis and cirrhosis, with serious consequences. NPC1L1 is involved in the regulation of cholesterol and lipid metabolism and plays an important role in maintaining the balance of cholesterol metabolism in the body. It also plays an important role in some metabolic diseases such as nonalcoholic fatty liver disease, obesity, and hypercholesterolemia. Therefore, it is necessary to elucidate the molecular pathological mechanism of NPC1L1 in the regulation of cholesterol metabolism and the occurrence and development of NASH, which can provide a target for the development of novel drugs for the treatment of NASH and other diseases. More importantly, it helps to accelerate the development of drugs that regulate lipid metabolism at multiple levels and reduce liver steatosis, which is extremely important for the prevention and treatment of NASH and related severe metabolic diseases.

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.

A genetic sum score of effect alleles associated with serum lipid concentrations interacts with educational attainment

High-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and total cholesterol (TC) levels are influenced by both genes and the environment. The aim was to investigate whether education and income as indicators of socioeconomic position (SEP) interact with lipid-increasing genetic effect allele scores (GES) in a population-based cohort. Using baseline data of 4516 study participants, age- and sex-adjusted linear regression models were fitted to investigate associations between GES and lipids stratified by SEP as well as including GES×SEP interaction terms. In the highest education group compared to the lowest stronger effects per GES standard deviation were observed for HDL-C (2.96 mg/dl [95%-CI: 2.19, 3.83] vs. 2.45 mg/dl [95%-CI: 1.12, 3.72]), LDL-C (6.57 mg/dl [95%-CI: 4.73, 8.37] vs. 2.66 mg/dl [95%-CI: −0.50, 5.76]) and TC (8.06 mg/dl [95%-CI: 6.14, 9.98] vs. 4.37 mg/dl [95%-CI: 0.94, 7.80]). Using the highest education group as reference, interaction terms showed indication of GES by low education interaction for LDL-C (ß_{GES×Education}: −3.87; 95%-CI: −7.47, −0.32), which was slightly attenuated after controlling for GES_LDL-C×Diabetes interaction (ß_{GES×Education}: −3.42; 95%-CI: −6.98, 0.18). The present study showed stronger genetic effects on LDL-C in higher SEP groups and gave indication for a GES_LDL-C×Education interaction, demonstrating the relevance of SEP for the expression of genetic health risks.

CYP7A1, NPC1L1, ABCB1, and CD36 Polymorphisms Are Associated with Increased Serum Coenzyme Q10 after Long-Term Supplementation in Women

Coenzyme Q₁₀ (CoQ₁₀), an essential component for energy production that exhibits antioxidant activity, is considered a health-supporting and antiaging supplement. However, intervention-controlled studies have provided variable results on CoQ₁₀ supplementation benefits, which may be attributed to individual CoQ₁₀ bioavailability differences. This study aimed to investigate the relationship between genetic polymorphisms and CoQ₁₀ serum levels after long-term supplementation. CoQ₁₀ levels at baseline and after one year of supplementation (150 mg) were determined, and eight single nucleotide polymorphisms (SNPs) in cholesterol metabolism and CoQ₁₀ absorption, efflux, and cellular uptake related genes were assessed. Rs2032582 (ABCB1) and rs1761667 (CD36) were significantly associated with a higher increase in CoQ₁₀ levels in women. In addition, in women, rs3808607 (CYP7A1) and rs2072183 (NPC1L1) were significantly associated with a higher increase in CoQ₁₀ per total cholesterol levels. Subgroup analyses showed that these four SNPs were useful for classifying high- or low-responder to CoQ₁₀ bioavailability after long-term supplementation among women, but not in men. On the other hand, in men, no SNP was found to be significantly associated with increased serum CoQ₁₀. These results collectively provide novel evidence on the relationship between genetics and CoQ₁₀ bioavailability after long-term supplementation, which may help understand and assess CoQ₁₀ supplementation effects, at least in women.

Genetics of Familial Hypercholesterolemia: New Insights

Familial hypercholesterolemia (FH) is one of the most common monogenic diseases, leading to an increased risk of premature atherosclerosis and its cardiovascular complications due to its effect on plasma cholesterol levels. Variants of three genes (LDL-R, APOB and PCSK9) are the major causes of FH, but in some probands, the FH phenotype is associated with variants of other genes. Alternatively, the typical clinical picture of FH can result from the accumulation of common cholesterol-increasing alleles (polygenic FH). Although the Czech Republic is one of the most successful countries with respect to FH detection, approximately 80% of FH patients remain undiagnosed. The opportunities for international collaboration and experience sharing within international programs (e.g., EAS FHSC, ScreenPro FH, etc.) will improve the detection of FH patients in the future and enable even more accessible and accurate genetic diagnostics.

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.

Genetic associations between serum low LDL-cholesterol levels and variants in LDLR, APOB, PCSK9 and LDLRAP1 in African populations

Non-communicable diseases, including cardiovascular diseases (CVDs), are increasing in African populations. High serum low density lipoprotein cholesterol (LDL-cholesterol) levels are a known risk factor for CVDs in European populations, but the link remains poorly understood among Africans. This study investigated the associations between serum LDL-cholesterol levels and selected variants in the low density lipoprotein receptor (LDLR), apolipoprotein B (APOB), proprotein convertase subtilisin/kexin type 9 (PCSK9) and low density lipoprotein receptor adaptor protein 1 (LDLRAP1) genes in some selected African populations. Nineteen SNPs were selected from publicly available African whole genome sequence data based on functional prediction and allele frequency. SNPs were genotyped in 1000 participants from the AWI-Gen, study selected from the extremes of LDL-cholesterol level distribution (500 with LDL-cholesterol>3.5 mmol/L and 500 with LDL-cholesterol<1.1 mmol/L). The minor alleles at five of the six associated SNPs were significantly associated (P<0.05) with lower LDL-cholesterol levels: LDLRAP1 rs12071264 (OR 0.56, 95% CI: 0.39-0.75, P = 2.73x10-4) and rs35910270 (OR 0.78, 95% CI: 0.64-0.94, P = 0.008); APOB rs6752026 (OR 0. 55, 95% CI: 0.41-0.72, P = 2.82x10-5); LDLR: rs72568855 (OR 0.47, 95% CI: 0.27-0.82, P = 0.008); and PCSK9 rs45613943 (OR = 0.72, 95% CI: 0.58-0.88, P = 0.001). The minor allele of the sixth variant was associated with higher LDL-cholesterol levels: APOB rs679899 (OR 1.41, 95% CI: 1.06-1.86, P = 0.016). A replication analysis in the Africa America Diabetes Mellitus (AADM) study found the PCSK9 variant to be significantly associated with low LDL-cholesterol levels (Beta = -0.10). Since Africans generally have lower LDL-cholesterol levels, these LDL-cholesterol associated variants may be involved in adaptation due to unique gene-environment interactions. In conclusion, using a limited number of potentially functional variants in four genes, we identified significant associations with lower LDL-cholesterol levels in sub-Saharan Africans.

Correlation Between the APOB rs1042034 SNP and Blood Lipid Characteristics of 2 Ethnic Groups in China

The apolipoprotein (Apo) B gene (APOB) is a susceptible gene for dyslipidemia. The purpose of this investigation was to explore the relationship between the APOB rs1042034 single-nucleotide polymorphism (SNP) and serum lipid levels in the Maonan and Han populations. A total of 598 Maonan participants and 609 Han participants were genotyped by polymerase chain reaction and restriction fragment length polymorphism, and the genotypes were also verified by sequencing. There were no differences in genotype and allele frequencies between the 2 ethnic groups or between males and females. The levels of triglyceride (TG) in Maonans were higher and high-density lipoprotein cholesterol was lower in the A allele carriers than the A allele noncarriers; the A allele carriers in Hans had higher TG levels and lower ApoA1/ApoB ratio than the A allele noncarriers (P < .05 for all). Subgroup analysis showed that the A allele carriers in Maonan females had higher TG levels and the A allele carriers in Han females had higher TG levels and lower ApoA1/ApoB ratio than the A allele noncarriers (P < .05 for all). In our study populations, there may be ethnicity- and/or sex-specific associations between the APOB rs1042034 SNP and serum lipid levels.

A multilocus genetic risk score is associated with arterial stiffness in hypertensive patients: the CARE NORTH study

INTRODUCTION

Arterial stiffness is recognized as an intermediate phenotype and predictor of cardiovascular disease. Arterial stiffness is complex in origin with contributions from lifestyle and genetic factors. However, the association between single nucleotide polymorphisms (SNPs) and arterial stiffness remains unclear.

OBJECTIVE

The aim is to assess whether a multilocus genetic risk score (GRS), composed of selected SNPs linked to cardiovascular traits and outcomes, is associated with arterial stiffness in patients with hypertension.

DESIGN AND METHODS

This study included 730 participants derived from the CARE NORTH study. The arterial stiffness was evaluated by carotid-femoral pulse wave velocity (cfPWV). An adjusted linear regression was used to evaluate the association between cfPWV and each individual SNP using multiple genetic models. The association between a constructed GRS and cfPWV was tested in an unadjusted and adjusted model.

RESULTS

We selected 13 SNPs found to be associated with cfPWV (P < .05): 6 SNPs in additive, 4 SNPs in recessive and 3 SNPs in dominant mode of inheritance. The GRS based on these SNPs was positively associated with cfPWV both in unadjusted and adjusted models (β = 0.2 m/s, 95% CI 0.11 - 0.29, P = 7.6 × 10 and β = 0.22 m/s, 95% CI 0.15 - 0.28, P = 1.4 × 10, respectively). The GRS explained an additional 3.6% cfPWV variance above clinical covariates.

CONCLUSION

We demonstrate that the GRS composed of 13 SNPs related to cardiovascular phenotypes is associated with an increased arterial stiffness in hypertensive patients. Our findings may help to clarify genetic basis of arterial stiffening and provide insight into mechanisms underlying this phenotype.

Multiple rare and common variants in APOB gene locus associated with oxidatively modified low-density lipoprotein levels

Oxidatively modified low-density lipoproteins (oxLDL) play an important role in the occurrence and progression of atherosclerosis. To identify the genetic factors influencing the oxLDL levels, we have genotyped 776 DNA samples of Russian individuals for 196,725 single-nucleotide polymorphisms (SNPs) using the Cardio-MetaboChip (Illumina, USA) and conducted genome-wide association study (GWAS). Fourteen common variants in the locus including APOB gene were significantly associated with the oxLDL levels (P < 2.18 × 10⁻⁷). These variants explained only 6% of the variation in the oxLDL levels. Then, we assessed the contribution of rare coding variants of APOB gene to the oxLDL levels. Individuals with the extreme oxLDL levels (48 with the lowest and 48 with the highest values) were selected for targeted sequencing of the region including APOB gene. To evaluate the contribution of the SNPs to the oxLDL levels we used various statistical methods for the association analysis of rare variants: WST, SKAT, and SKAT-O. We revealed that both synonymous and nonsynonymous SNPs affected the oxLDL levels. For the joint analysis of the rare and common variants, we conducted the SKAT-C testing and found a group of 15 SNPs significantly associated with the oxLDL levels (P = 2.14 × 10⁻⁹). Our results indicate that the oxLDL levels depend on both common and rare variants of the APOB gene.

Molecular analysis of APOB, SAR1B, ANGPTL3, and MTTP in patients with primary hypocholesterolemia in a clinical laboratory setting: Evidence supporting polygenicity in mutation-negative patients

BACKGROUND AND AIMS

Primary hypobetalipoproteinemia is generally considered a heterogenic group of monogenic, inherited lipoprotein disorders characterized by low concentrations of LDL cholesterol and apolipoprotein B in plasma. Lipoprotein disorders include abetalipoproteinemia, familial hypobetalipoproteinemia, chylomicron retention disease, and familial combined hypolipidemia. Our aim was to review and analyze the results of the molecular analysis of hypolipidemic patients studied in our laboratory over the last 15 years.

METHODS

The study included 44 patients with clinical and biochemical data. Genomic studies were performed and genetic variants were characterized by bioinformatics analysis. A weighted LDL cholesterol gene score was calculated to evaluate common variants associated with impaired lipid concentrations and their distribution among patients.

RESULTS

Twenty-three patients were genetically confirmed as affected by primary hypobetalipoproteinemia. In this group of patients, the most prevalent mutated genes were APOB (in 17 patients, with eight novel mutations identified), SAR1B (in 3 patients, with one novel mutation identified), ANGPTL3 (in 2 patients), and MTTP (in 1 patient). The other 21 patients could not be genetically diagnosed with hypobetalipoproteinemia despite presenting suggestive clinical and biochemical features. In these patients, two APOB genetic variants associated with lower LDL cholesterol were more frequent than in controls. Moreover, the LDL cholesterol gene score, calculated with 11 SNPs, was significantly lower in mutation-negative patients.

CONCLUSIONS

Around half of the patients could be genetically diagnosed. The results suggest that, in at least some of the patients without an identified mutation, primary hypobetalipoproteinemia may have a polygenic origin.

APOB codon 4311 polymorphism is associated with hepatitis C virus infection through altered lipid metabolism

Background

It has been reported that some single-nucleotide polymorphisms (SNPs) in lipid regulators such as apolipoproteins and cell surface molecules for hepatitis C virus (HCV) entry into hepatocytes are associated with HCV infection. However, it is unknown how HCV infection is affected by altered lipid metabolism resulting from the SNPs. We investigated the relationship between these SNPs and HCV infection status, and also analyzed the mechanism by which these SNPs mediate HCV infection via lipid metabolism alterations.

Methods

Serum lipid and apolipoprotein profiles were tested in 158 HCV-positive and 220 HCV-negative subjects. We selected 22 SNPs in five lipid regulator genes which were related to HCV entry into hepatocytes and to lipid metabolism (APOA1, APOB, SR-B1, LDLR, and APOE), and their polymorphisms were analyzed using the PCR-sequence-specific oligonucleotide probe-Luminex method.

Results

An APOB N4311S (g.41553a > g) SNP, rs1042034, was significantly associated with HCV positivity; the HCV positivity rate for the minor allele AA genotype was significantly higher than for genotype AG + GG (P = 0.016). Other SNPs except for APOB P2712L SNP rs676210, which is in linkage disequilibrium with rs1042034, showed no significant difference in genotype distribution. The serum level of low density lipoprotein-cholesterol (LDL-C) in the genotype AA group was significantly lower than in the genotype non-AA group (P = 0.032), whereas the triglyceride (TG) level was significantly higher (P = 0.007).

Conclusion

An APOB SNP, rs1042034, is closely associated with HCV infection through lipid metabolism alteration. The minor allele AA genotype might contribute to facilitating serum LDL uptake into hepatocytes via LDLR by modifying their affinity and interaction and may have an influence on HCV infection by their entry to the liver through the LDLR.

Variants in the APOB gene was associated with Ischemic Stroke susceptibility in Chinese Han male population

Background

Stroke is an extremely complicated disease caused by multiple factors. Epidemiological studies have shown that genetic factors contribute to the pathogenesis of stroke. There is still little research on the effect of ApoB gene on stroke in Chinese Han population. The purpose of our research was to explore the effect of ApoB gene polymorphism on the genetic susceptibility to Ischemic Stroke in Chinese Han male population.

Materials and methods

7 polymorphisms in ApoB gene were selected and genotyped using Sequenom MassARRAY in 325 ischemic stroke male patients and 399 healthy male controls in Chinese Han population. The association between ApoB gene and genetic susceptibility to Ischemic Stroke was performed by the χ² test, genetic model analysis and haplotype analysis.

Results

In the allele model, ApoB rs1042034 “T” allele and rs673548 “G” allele increased the risk of the Ischemic Stroke (rs1042034: OR=1.29, 95%CI: 1.02-1.63, p=0.030; rs673548: OR=1.28, 95%CI: 1.02-1.62, p=0.034). Logistic regression analysis found that ApoB rs1042034 and rs673548 increased the risk of Ischemic Stroke in the log-additive model, the odds of having Ischemic Stroke would be 1.28-fold and 1.27-fold with the variant allele, respectively. We also found that the risk of individuals carrying the ApoB rs693 “AA-AG” genotype had Ischemic Stroke risk of 1.52-fold of carrying “GG” genotype in the dominant model. The haplotype analysis shown that “TAG” haplotype raised the risk of Ischemic Stroke (OR=1.52, 95%CI: 1.02-2.27, p=0.0042).

Conclusion

The polymorphisms of the ApoB gene may affect Ischemic Stroke occurrence.

Association between polymorphisms in the APOB gene and hyperlipidemia in the Chinese Yugur population

We investigated the influence of apolipoprotein B gene (APOB) variants on the risk of hyperlipidemia (HL) in 631 middle-aged and elderly members of the Chinese Yugur population (HL, n=336; normolipidemia, n=295). APOB polymorphisms were identified using mass spectrometry, and five single nucleotide polymorphisms (rs1042034, rs2163204, rs512535, rs676210, and rs679899) and serum lipids were further analyzed. rs1042034 and rs676210 were significantly associated with HL (P<0.05). Compared with the GG or AA genotype, individuals with AG and AG+AA in rs1042034 and with AG and AG+GG in rs676210 had a 1.67-fold (95%CI=1.20-2.33),1.63-fold (95%CI=1.19-2.24), 1.72-fold (95%CI=1.24-2.40), and 1.67-fold (95%CI=1.21-2.291) increased risk of high HL, respectively. rs2163204 was in strong linkage disequilibrium with rs1042034, rs676210, and rs679899, and strong disequilibrium was observed between rs1042034 and rs676210 (D'>0.9). Compared with the GTGAA haplotype, haplotypes ATGGA and ATAGG were more strongly associated with HL [odds ratio (OR)=1.46, 95%CI=0.02-2.11; OR=1.63, 95%CI=1.03-2.60, respectively]. The risk factors age (P=0.008), body mass index (P<0.0001), GA+GG genotype in rs676210 (P=0.009), and alcohol consumption (P=0.056) contributed strongly to HL development. The A allele of rs1042034 and the G allele of rs676210 may thus predispose middle-aged and elderly members of the Chinese Yugur population to HL in combination with other genetic or nutritional factors, and could be used as new genetic markers for HL screening.

Shared polymorphisms and modifiable behavior factors for myocardial infarction and high cholesterol in a retrospective population study

Genetic and environmental (behavior, clinical, and demographic) factors are associated with increased risks of both myocardial infarction (MI) and high cholesterol (HC). It is known that HC is major risk factor that may cause MI. However, whether there are common single nucleotide polymorphism (SNPs) associated with both MI and HC is not firmly established, and whether there are modulate and modified effects (interactions of genetic and known environmental factors) on either HC or MI, and whether these joint effects improve the predictions of MI, is understudied.The purpose of this study is to identify novel shared SNPs and modifiable environmental factors on MI and HC. We assess whether SNPs from a metabolic pathway related to MI may relate to HC; whether there are moderate effects among SNPs, lifestyle (smoke and drinking), HC, and MI after controlling other factors [gender, body mass index (BMI), and hypertension (HTN)]; and evaluate prediction power of the joint and modulate genetic and environmental factors influencing the MI and HC.This is a retrospective study with residents of Erie and Niagara counties in New York with a history of MI or with no history of MI. The data set includes environmental variables (demographic, clinical, lifestyle). Thirty-one tagSNPs from a metabolic pathway related to MI are genotyped. Generalized linear models (GLMs) with imputation-based analysis are conducted for examining the common effects of tagSNPs and environmental exposures and their interactions on having a history of HC or MI.MI, BMI, and HTN are significant risk factors for HC. HC shows the strongest effect on risk of MI in addition to HTN; gender and smoking status while drinking status shows protective effect on MI. rs16944 (gene IL-1β) and rs17222772 (gene ALOX) increase the risks of HC, while rs17231896 (gene CETP) has protective effects on HC either with or without the clinical, behavioral, demographic factors with different effect sizes that may indicate the existence of moderate or modifiable effects. Further analysis with the inclusions of gene-gene and gene-environmental interactions shows interactions between rs17231896 (CETP) and rs17222772 (ALOX); rs17231896 (CETP) and gender. rs17237890 (CETP) and rs2070744 (NOS3) are found to be significantly associated with risks of MI adjusted by both SNPs and environmental factors. After multiple testing adjustments, these effects diminished as expected. In addition, an interaction between drinking and smoking status is significant. Overall, the prediction power in successfully classifying MI status is increased to 80% with inclusions of all significant tagSNPs and environmental factors and their interactions compared with environmental factors only (72%).Having a history of either HC or MI has significant effects on each other in both directions, in addition to HTN and gender. Genes/SNPs identified from this analysis that are associated with HC may be potentially linked to MI, which could be further examined and validated through haplotype-pairs analysis with appropriate population stratification corrections, and function/pathway regulation analysis to eliminate the limitations of the current analysis.

Mediterranean diet-gene interactions: A targeted metabolomics study in Greek-Cypriot women

SCOPE

A high adherence to the Mediterranean diet (MD) was previously associated with a decreased risk of breast cancer (BC) among Greek-Cypriot women. Additionally, particular polymorphisms were shown to modulate this MD-BC association. Herein, we aimed to investigate the effect of polymorphisms-MD interactions on the levels of specific metabolites that could be related to dietary adherence or enzymatic activity, which is itself modulated by polymorphisms.

METHODS AND RESULTS

Greek-Cypriot women who were BC controls and had the lowest or the highest MD adherence (vegetables, fruit, legumes, fish) as assessed by principal component analysis (n = 564) were included. Participants were previously genotyped for nine polymorphisms of the one-carbon metabolism, oxidative stress, and xenobiotic metabolism. The serum levels of 14 metabolites that are key players in the aforementioned pathways were measured by UPLC-MS/MS. ANCOVA was used to assess polymorphism-MD interactions on metabolites' levels within a multivariate linear regression model. Statistically significant interactions between GSTM1 (where GST is glutathione S-transferase) deletion polymorphism and MD on flavin mononucleotide and on 5-methyltetrahydrofolate (5-MTHF) concentrations were observed. The MTHFR rs1801133 interacted significantly with MD on 5-MTHF concentration.

CONCLUSION

Serum levels of flavin mononucleotide and 5-MTHF were shown to be influenced by interactions between GSTM1 deletion or MTHFR (rs1801133) polymorphisms and a dietary pattern, characteristic of MD.

Genetic variations of the NPC1L1 gene associated with hepatitis C virus (HCV) infection and biochemical characteristics of HCV patients in China

OBJECTIVES

About 2% of the world population is infected with hepatitis C virus (HCV), a leading cause of hepatic cirrhosis and hepatocellular carcinoma. The Niemann-Pick C1-like 1 cholesterol absorption receptor (NPC1L1) was recently identified to be an important factor for HCV entry into host cells. Whether genetic variations of the NPC1L1 gene are associated with HCV infection is unknown.

METHODS

In this study, five single nucleotide polymorphisms (SNPs) of the NPC1L1 gene were analyzed in 261 HCV-infected individuals and 265 general controls from Yunnan Province, China.

RESULTS

No significant differences were identified in genotypes or alleles of the SNPs between the two groups. After constructing haplotypes based on the five SNPs, a significant difference between HCV-infected individuals and general controls was shown for two haplotypes. Haplotype GCCTT appeared to be a protective factor and haplotype GCCCT was a risk factor for HCV-infected individuals. Genotypes of four SNPs correlated with biochemical characteristics of HCV-infected persons. Genotypes of SNPs rs799444 and rs2070607 were correlated with total bilirubin. Genotype TT of rs917098 was a risk factor for the gamma-glutamyltransferase level. Furthermore, HCV-infected individuals carrying genotype GG of rs41279633 showed statistically higher gamma-glutamyltransferase levels than HCV-infected persons with GT and TT.

CONCLUSION

The results of this study identified the association between genetic susceptibility of the NPC1L1 gene and HCV infection, as well as biochemical characteristics of HCV-infected persons in Yunnan, China.

Polymorphisms in ApoB gene are associated with risk of myocardial infarction and serum ApoB levels in a Chinese population

Myocardial infarction (MI) is a serious result of coronary artery disease. Recent data from clinical trials have showed that the risk of MI was associated with high plasma apolipoprotein B (apoB) levels. Mutations in ApoB gene were also found to be associated with plasma lipid levels. The aim of this study is to evaluate the effect of ApoB polymorphisms on the risk of MI and plasma apoB levels in a Chinese population. Eight polymorphisms (rs676210, rs679899, rs3791980, rs2854725, rs11676704, rs512535, rs12720841 and rs2678379) in ApoB gene were genotyped in a case-control study in China, including 550 MI cases and 550 healthy controls. Carriers of GG genotype of rs676210 had significant increased risk of MI [odd ratio (OR) = 1.93, 95% confidence interval (CI): 1.23-3.03] compared to carriers of AA genotype. Haplotype analysis also showed that GTTGG (rs676210-rs2854725-rs11676704-rs3791980-rs2678379) haplotype had significant increased risk of MI (OR = 2.82, 95% CI: 1.49-5.33) compared with ATTGA haplotype. Furthermore, apoB rs676210 and rs2678379 polymorphisms were significantly associated with plasma levels of apoB in healthy controls (P = 0.01 and 0.02). Our findings indicated that ApoB mutations may be associated with the risk of MI and plasma ApoB levels in healthy controls in Chinese population.

Genetic association of the ApoB and ApoA1 gene polymorphisms with the risk for alcohol-induced osteonecrosis of femoral head

Polymorphisms of apolipoprotein B (ApoB), apolipoprotein A1 (ApoA1) gene and ApoB/ApoA1 Ratio were associated with lipid metabolism disorders in previous reports. The aim of this study assess whether variation of ApoB, ApoA1 gene are associated or not with alcohol-induced osteonecrosis of femoral head (ONFH). In a case-control study, we genotyped 4 single-nucleotide polymorphisms (SNPs) in ApoB and ApoA1 genes in 209 alcohol-induced ONFH patients and 300 healthy control subjects in Han Chinese population using χ(2) test and genetic model analysis. The analysis revealed that the frequencies of ApoB and ApoA1 genotypes were significantly different in alcohol-induced ONFH patients than in controls. We identified rs1042034, rs676210 and rs673548 in ApoB gene were associated with decreased risk of alcohol-induced ONFH using recessive model analysis (odds ratio [OR], 0.44; 95% confidence interval [CI], 0.19-0.99; P = 0.042), the OR, CI, P value of three SNPs were the same after adjusted for gender + age. We also identified rs632153 in ApoA1 gene was associated with increased risk of alcohol-induced ONFH using allele model (OR, 1.83; 95% CI, 1.16-2.88; P = 0.008) and log-additive model (adjusted OR, 1.77; 95% CI, 1.00-3.14; P = 0.046), analysis respectively. Haplotype analysis demonstrated no difference between ApoB and alcohol-induced ONFH. Polymorphisms of the ApoB and ApoA1 gene are associated with alcohol-induced ONFH in the Han Chinese population.

Trends in dietary cholesterol intake among Chinese adults: a longitudinal study from the China Health and Nutrition Survey, 1991-2011

OBJECTIVES

Dietary cholesterol is the leading risk factor for cardiovascular disease and other chronic diseases. Changes in dietary patterns in China recently might have an impact on the trends of diet-related risk factors of chronic diseases. This study aims to monitor the changes in daily cholesterol intake and its food sources in Chinese adults.

DESIGN

A longitudinal study using demographic and dietary data of adults younger than 60 years from eight waves (1991-2011) of the China Health and Nutrition Surveys was conducted. Mixed-effect models were used in this study.

SETTING

The data were derived from urban and rural communities in nine provinces (autonomous regions) in China.

PARTICIPANTS

There were 21,273 participants (10,091 males and 11,182 females) in this study.

OUTCOMES

The major outcome is daily cholesterol intake amount, which was calculated by using the Chinese Food Composition Table, based on dietary data.

RESULTS

The mean daily cholesterol intake in Chinese adults increased from 165.8 mg/day in 1991 to 266.3 mg/day in 2011. Cholesterol consumed by participants in different age (18-39 and 40-59 years), sex and urbanisation groups steadily elevated over time (p<0.0001), as did the proportions of participants with greater than 300 mg/day cholesterol consumption. In each subgroup, cholesterol originating from most of the food groups showed increasing trends over time (p<0.0001), except for animal fat and organ meats. Eggs, pork, fish and shellfish in that order remained the top three sources in 1991, 2000 and 2011, whereas milks were a negligible contributor. Cholesterol from animal fat declined and was insignificant in 2011 in most of the subgroups, while cholesterol being of poultry origin increased and became considerable in 2011.

CONCLUSIONS

Adults in China consumed increasingly high cholesterol and deviated from the recommended intake level over the past two decades. Adults need to pay more attention to intakes of eggs, pork, fish and shellfish.

PLTP activity inversely correlates with CAAD: effects of PON1 enzyme activity and genetic variants on PLTP activity

Recent studies have failed to demonstrate a causal cardioprotective effect of HDL cholesterol levels, shifting focus to the functional aspects of HDL. Phospholipid transfer protein (PLTP) is an HDL-associated protein involved in reverse cholesterol transport. This study sought to determine the genetic and nongenetic predictors of plasma PLTP activity (PLTPa), and separately, to determine whether PLTPa predicted carotid artery disease (CAAD). PLTPa was measured in 1,115 European ancestry participants from a case-control study of CAAD. A multivariate logistic regression model was used to elucidate the relationship between PLTPa and CAAD. Separately, a stepwise linear regression determined the nongenetic clinical and laboratory characteristics that best predicted PLTPa. A final stepwise regression considering both nongenetic and genetic variables identified the combination of covariates that explained maximal PLTPa variance. PLTPa was significantly associated with CAAD (7.90 × 10(-9)), with a 9% decrease in odds of CAAD per 1 unit increase in PLTPa (odds ratio = 0.91). Triglyceride levels (P = 0.0042), diabetes (P = 7.28 × 10(-5)), paraoxonase 1 (PON1) activity (P = 0.019), statin use (P = 0.026), PLTP SNP rs4810479 (P = 6.38 × 10(-7)), and PCIF1 SNP rs181914932 (P = 0.041) were all significantly associated with PLTPa. PLTPa is significantly inversely correlated with CAAD. Furthermore, we report a novel association between PLTPa and PON1 activity, a known predictor of CAAD.

Nutritional Supplementation with Essential Amino Acids and Phytosterols May Reduce Risk for Metabolic Syndrome and Cardiovascular Disease in Overweight Individuals with Mild Hyperlipidemia

BACKGROUND

Hyperlipidemia and insulin resistance are risk factors for the development of metabolic syndrome and cardiovascular disease. We have previously observed that supplementation with essential amino acids (EAA) could lower plasma triglycerides, and may improve glucose metabolism.

OBJECTIVE

We sought to determine whether EAA's combined with whey protein and phytosterols would facilitate improvements in plasma lipids and insulin sensitivity in adults with mild hypertriglyceridemia.

DESIGN

We enrolled nine subjects who were 50 years or older, had a documented plasma TG >150 mg/dl, and had not recently taken statin medications (within 6 weeks). Each subject served as his or her own control. These individuals underwent an oral glucose tolerance test (OGTT) before and after four weeks consumption of the oral nutritional supplement without dietary counseling or recommendations for physical activity.

RESULTS

Plasma total cholesterol and LDL levels decreased in all nine volunteers (P<0.005 for cholesterol and P<0.02 for LDL). In six of these individuals, plasma triglycerides (TG) fell by 95±13 mg/dl (P=0.007); while the other three showed no TG reduction. Genotyping revealed that in two of the three individuals that did not have TG reduction in response to the nutritional supplementation. Insulin sensitivity (ISI) and the total AUC_ins/glucose were significantly reduced by leucine/EAAs and phytosterol supplementation (P=0.008).

CONCLUSIONS

These findings suggest that a dietary supplementation of EAAs and phytosterols may promote favorable reductions of blood lipids as well as insulin resistance in individuals with hypertriglyceridemia. Future larger studies of SNPs and TG response to dietary supplements will be of interest.

Gene-environment interaction in dyslipidemia

PURPOSE OF REVIEW

Recent genome-wide association studies have identified numerous common genetic variants associated with plasma lipid traits and have provided new insights into the regulation of lipoprotein metabolism including the identification of novel biological processes. These findings add to a body of existing data on dietary and environmental factors affecting plasma lipids. Here we explore how interactions between genetic risk factors and other phenotypes may explain some of the missing heritability of plasma lipid traits.

RECENT FINDINGS

Recent studies have identified true statistical interaction between several environmental and genetic risk factors and their effects on plasma lipid fractions. These include interactions between behaviors such as smoking or exercise as well as specific dietary nutrients and the effect size of specific genetic variants on plasma lipid traits risk and modifying effects of measures of adiposity on the cumulative impact of a number of common genetic variants on each of plasma triglycerides and HDL cholesterol.

SUMMARY

Interactions between genetic risk factors and clinical phenotypes may account for some of the unexplained heritability of plasma lipid traits. Recent studies provide biological insight into specific genetic associations and may aid in the identification of dyslipidemic patients for whom specific lifestyle interventions are likely to be most effective.

Potential effects of NPC1L1 polymorphisms in protecting against clinical disease in a chinese family with sitosterolaemia

Sitosterolaemia is caused by mutations in either ABCG5 or ABCG8. Chinese and Japanese individuals usually have mutations in ABCG5. We herein report a known and a novel mutation in ABCG8 and their potential interaction with NPC1L1 polymorphisms in a Chinese family with sitosterolaemia. We sequenced ABCG5 and ABCG8 and measured the levels of plasma plant sterols in a 15-year-old Chinese girl with clinical sitosterolaemia (xanthomas with elevated low-density lipoprotein cholesterol (LDL-C) and plant sterols) and her apparently healthy family members. NPC1L1 was sequenced in the genetically affected sibling and other family members. A known mutation, c.490C＞T (p. Arg164(＊)), in exon 4 and a novel mutation, c.1949T＞G (p.Leu650Arg), in exon 13 of ABCG8 were detected in the proband and her sister, who had elevated sterols but low LDL-C levels and no xanthomas. The genetically affected sister, but not the proband, carried two additional heterozygous changes in NPC1L1 (rs2072183 C＞G, rs2301935 A＞C), which were inherited from the mother, who also had a low LDL-C level. In this study, we detected a known and a novel mutation in ABCG8 in a Chinese patient with sitosterolaemia. The same mutations were found in her clinically normal sister, suggesting that the contrasting features with the proband may be related to different variants in NPC1L1 and/or some other undetermined lipid-related genetic factors.

HDL-3 is a superior predictor of carotid artery disease in a case-control cohort of 1725 participants

Background

Recent data suggest that high‐density lipoprotein cholesterol (HDL‐C) levels are likely not in the causative pathway of atheroprotection, shifting focus from HDL‐C to its subfractions and associated proteins. This study's goal was to determine which HDL phenotype was the better predictor of carotid artery disease (CAAD).

Methods and Results

HDL‐2 and HDL‐3 were measured in 1725 participants of European ancestry in a prevalent case‐control cohort study of CAAD. Stratified analyses were conducted for men (n=1201) and women (n=524). Stepwise linear regression was used to determine whether HDL‐C, HDL‐2, HDL‐3, or apolipoprotein A1 was the best predictor of CAAD, while adjusting for the confounders of censored age, diabetes, and current smoking status. In both men and women, HDL‐3 was negatively associated with CAAD (P=0.0011 and 0.033 for men and women, respectively); once HDL‐3 was included in the model, no other HDL phenotype was significantly associated with CAAD. Addition of paraoxonase 1 activity to the aforementioned regression model showed a significant and independent (of HDL‐3) association with CAAD in men (P=0.001) but not in the smaller female subgroup.

Conclusions

This study is the first to contrast the associations of HDL‐2 and HDL‐3 with CAAD. We found that HDL‐3 levels were more predictive of CAAD status than HDL‐2, HDL‐C, or apolipoprotein A1. In addition, for men, paraoxonase 1 activity improved the overall model prediction for CAAD independently and additively with HDL‐3 levels. Further investigation into the molecular mechanisms through which HDL‐3 is associated with protection from CAAD is warranted.

Pharmacogenomics, lipid disorders, and treatment options

Statins form the backbone of lipid-lowering therapy in the prevention of cardiovascular disease. Numerous studies have evaluated the effect of genomics on the clinical efficacy and adverse effects of statins. Several gene variants that can be linked to either the pharmacokinetics or pharmacodynamics of statins have been identified as potentially important, although there are some discrepant findings among studies. Effect sizes are modest for lipid-lowering efficacy and perhaps somewhat larger for risk of myopathy, although results are inconsistent. Pharmacogenomics of nonstatin lipid-lowering agents have not been evaluated to the same extent, given their relatively limited use, although there are some promising candidate genes for further study. Finally, with several new classes of lipid-lowering therapies soon becoming available, there may be a potential application for pharmacogenomics to identify patients ideally suited to receive-or those who should avoid-specific medications.

Rare coding variation in paraoxonase-1 is associated with ischemic stroke in the NHLBI Exome Sequencing Project

HDL-associated paraoxonase-1 (PON1) is an enzyme whose activity is associated with cerebrovascular disease. Common PON1 genetic variants have not been consistently associated with cerebrovascular disease. Rare coding variation that likely alters PON1 enzyme function may be more strongly associated with stroke. The National Heart, Lung, and Blood Institute Exome Sequencing Project sequenced the coding regions (exomes) of the genome for heart, lung, and blood-related phenotypes (including ischemic stroke). In this sample of 4,204 unrelated participants, 496 had verified, noncardioembolic ischemic stroke. After filtering, 28 nonsynonymous PON1 variants were identified. Analysis with the sequence kernel association test, adjusted for covariates, identified significant associations between PON1 variants and ischemic stroke (P = 3.01 × 10(-3)). Stratified analyses demonstrated a stronger association of PON1 variants with ischemic stroke in African ancestry (AA) participants (P = 5.03 × 10(-3)). Ethnic differences in the association between PON1 variants with stroke could be due to the effects of PON1Val109Ile (overall P = 7.88 × 10(-3); AA P = 6.52 × 10(-4)), found at higher frequency in AA participants (1.16% vs. 0.02%) and whose protein is less stable than the common allele. In summary, rare genetic variation in PON1 was associated with ischemic stroke, with stronger associations identified in those of AA. Increased focus on PON1 enzyme function and its role in cerebrovascular disease is warranted.

Dietary fatty acid intake is associated with paraoxonase 1 activity in a cohort-based analysis of 1,548 subjects

BACKGROUND

Paraoxonase 1 (PON1) is a cardioprotective, HDL-associated glycoprotein enzyme with broad substrate specificity. Our previous work found associations between dietary cholesterol and vitamin C with PON1 activity. The goal of this study was to determine the effect of specific dietary fatty acid (DFA) intake on PON1 activity.

METHODS

1,548 participants with paraoxonase activity measures completed the Harvard Standardized Food Frequency Questionnaire to determine their daily nutrient intake over the past year. Eight saturated, 3 monounsaturated, and 6 polyunsaturated DFAs were measured by the questionnaire. To reduce the number of observations tested, only specific fatty acids that were not highly correlated (r < 0.8) with other DFAs or that were representative of other DFAs through high correlation within each respective group (saturated, monounsaturated, or polyunsaturated) were retained for analysis. Six specific DFA intakes - myristic acid (14 carbon atoms, no double bonds - 14:0), oleic acid (18:1), gadoleic acid (20:1), α-linolenic acid (18:3), arachidonic acid (20:4), and eicosapentaenoic acid (20:5) - were carried forward to stepwise linear regression, which evaluated the effect of each specific DFA on covariate-adjusted PON1 enzyme activity.

RESULTS

Four of the 6 tested DFA intakes - myristic acid (p = 0.038), gadoleic acid (p = 6.68 × 10(-7)), arachidonic acid (p = 0.0007), and eicosapentaenoic acid (p = 0.013) - were independently associated with covariate-adjusted PON1 enzyme activity. Myristic acid, a saturated fat, and gadoleic acid, a monounsaturated fat, were both positively associated with PON1 activity. Both of the tested polyunsaturated fats, arachidonic acid and eicosapentaenoic acid, were negatively associated with PON1 activity.

CONCLUSIONS

This study presents the largest cohort-based analysis of the relationship between dietary lipids and PON1 enzyme activity. Further research is necessary to elucidate and understand the specific biological mechanisms, whether direct or regulatory, through which DFAs affect PON1 activity.