Endothelial lipase gene polymorphism is associated with acute myocardial infarction, independently of high-density lipoprotein-cholesterol levels

Endothelial lipase variant T111I does not alter inhibition by angiopoietin-like proteins

High levels of HDL-C are correlated with a decreased risk of cardiovascular disease. HDL-C levels are modulated in part by the secreted phospholipase, endothelial lipase (EL), which hydrolyzes the phospholipids of HDL and decreases circulating HDL-C concentrations. A 584C/T polymorphism in LIPG, the gene which encodes EL, was first identified in individuals with increased HDL levels. This polymorphism results in a T111I point mutation the EL protein. The association between this variant, HDL levels, and the risk of coronary artery disease (CAD) in humans has been extensively studied, but the findings have been inconsistent. In this study, we took a biochemical approach, investigating how the T111I variant affected EL activity, structure, and stability. Moreover, we tested whether the T111I variant altered the inhibition of phospholipase activity by angiopoietin-like 3 (ANGPTL3) and angiopoietin-like 4 (ANGPTL4), two known EL inhibitors. We found that neither the stability nor enzymatic activity of EL was altered by the T111I variant. Moreover, we found no difference between wild-type and T111I EL in their ability to be inhibited by ANGPTL proteins. These data suggest that any effect this variant may have on HDL-C levels or cardiovascular disease are not mediated through alterations in these functions.

Endothelial Lipase Variant, T111I, Does Not Alter Inhibition by Angiopoietin-like Proteins

High levels of HDL-C are correlated with a decreased risk of cardiovascular disease. HDL-C levels are modulated in part by the secreted phospholipase, endothelial lipase (EL), which hydrolyzes the phospholipids of HDL and decreases circulating HDL-C concentrations. A 584C/T polymorphism in LIPG, the gene which encodes EL, was first identified in individuals with increased HDL levels. This polymorphism results in a T111I point mutation the EL protein. The association between this variant, HDL levels, and the risk of coronary artery disease (CAD) in humans has been extensively studied, but the findings have been inconsistent. In this study, we took a biochemical approach, investigating how the T111I variant affected EL activity, structure, and stability. Moreover, we tested whether the T111I variant altered the inhibition of phospholipase activity by angiopoietin-like 3 (ANGPTL3) and angiopoietin-like 4 (ANGPTL4), two known EL inhibitors. We found that neither the stability nor enzymatic activity of EL was altered by the T111I variant. Moreover, we found no difference between wild-type and T111I EL in their ability to be inhibited by ANGPTL proteins. These data suggest that any effect this variant may have on HDL-C levels or cardiovascular disease are not mediated through alterations in these functions.

Roles of endothelial lipase gene related single nucleotide polymorphisms in patients with coronary artery disease

The current work focused on evaluating the roles of endothelial lipase gene (LIPG) related single nucleotide polymorphisms (SNPs) in patients with coronary artery disease (CAD). This study involved 1,883 subjects with 959 CAD patients and 924 healthy controls. Data were harvested to assess the association of LIPG related SNPs including rs3744841, rs3744843, rs3813082 and rs2000813 with the risk of CAD. The CC + AC genotype in rs3813082 played a protective role for CAD [odds ratio (OR) = 0.709, P = 0.039]. Differences existed in apolipoprotein-A1 (Apo-A1) and high-density lipoprotein-cholesterol (HDL-C) levels in rs3744843 variant between control and CAD groups. The rs3744841 variant increased the levels of total cholesterol (TC), HDL-C, low-density lipoprotein cholesterol (LDL-C), Apo-A1 and Lipoprotein a (LPa) in the CAD group and TC, LDL-C, HDL-C, Apo-B, Apo-A1 in the control group. The triglyceride (TG) level was lower in rs2000813 variant in the CAD group and elevated in the control group. The rs2000813 variant decreased the number of vascular stenosis while rs3744843 and rs3744841 variants increased the number of vascular stenosis in CAD patients. This study explored the roles of LIPG related SNPs in CAD, showing that CC + AC genotype in rs3813082 was a protective factor for CAD. The rs3744843, rs3744841 and rs2000813 variants were associated with the levels of lipid parameters in CAD patients. The rs3744843, rs3744841 and rs2000813 variants influenced the number of vascular stenosis in CAD patients. The results of our study might be a promising reference for preventing CAD.

Significant association between the endothelial lipase gene 584C/T polymorphism and coronary artery disease risk

Several studies have investigated a potential association between the endothelial lipase gene (LIPG) 584C/T polymorphism and susceptibility to coronary artery disease (CAD), but a uniform conclusion is yet to be reached. To better evaluate the true relationship between the LIPG 584C/T polymorphism and the risk of CAD, a meta-analysis of 14 case-control studies with 9731 subjects was performed. Relevant articles published through August 2020 were searched in the CNKI, PubMed, Embase and Web of Science databases. Thirteen articles, including 14 eligible case-control studies with 4025 cases and 5706 controls, were enrolled in the present meta-analysis. The Newcastle-Ottawa Scale (NOS) scores of the case-control studies ranged from 6 to 8. The pooled results indicated that there is a significant association between the LIPG 584C/T polymorphism and CAD in the homozygote comparison model and the allelic comparison model. Subgroup analyses revealed that the LIPG 584C/T mutation significantly decreased the risk of CAD in the subgroups of African, CAD, hospital-based (HB), and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) populations in some genetic models. No publication bias was found in our meta-analysis, which certifies the robustness of the current meta-analysis. Trial sequential analysis (TSA) also confirmed the stability of our results. The results of our meta-analysis indicate that the LIPG 584C/T polymorphism plays a protective role in the incidence of CAD. More high-quality case-control studies on various ethnicities are needed to confirm our results.

Gene polymorphism associated with angiotensinogen (M235T), endothelial lipase (584C/T) and susceptibility to coronary artery disease: a meta-analysis

OBJECTIVE

To explore the association between the variant M235T locus of angiotensinogen (AGT) gene, 584C/T locus of Endothelial lipase (EL) gene, and coronary artery disease (CAD) by meta-analysis.

METHODS

The case-control studies on the association between AGT/EL gene polymorphism and CAD were collected through searching PubMed, Excerpta Medica Database (EMBASE), Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases up to 1 March 2020. Stata 15.0 software was used for analysis.

RESULTS

A total of 29 articles met the inclusion criteria. After analyzing, it was found that the M235T polymorphism of AGT gene was associated with the occurrence of CAD. In the allele model (T vs. M), OR = 1.38 (P<v0.05). In other heredity, there was also statistical significance. Subgroup analysis indicated that except the heterozygous genetic model of the Chinese population, other genetic models of the Caucasian and Chinese population were also statistically significant. The 584C/T polymorphism of EL gene was associated with the occurrence of CAD, with OR = 0.83 (P<0.05) in the allele model (T vs. C) and OR = 0.80 (P<0.05) in the dominant gene model. Also, in the allele model of Caucasian subgroup, OR = 0.83 (P<0.05), while in Asian subgroup, there was no statistically significant genetic model.

CONCLUSION

AGT M235T and EL 584C/T polymorphisms are associated with CAD susceptibility. The genotype TT, TC or allele T of AGT M235T and genotype CC or allele C of EL 584C/T might be the genetic risk factors for the development of CAD.

Association of genetic variants in lncRNA GAS5/miR-21/mTOR axis with risk and prognosis of coronary artery disease among a Chinese population

Background

Allowing for the significance of single nucleotide polymorphisms (SNPs) in reflecting disease risk, this investigation attempted to uncover whether SNPs situated in lncRNA GAS5/miR‐21/mTOR axis were associated with risk and prognosis of coronary heart disease (CHD) among a Chinese Han population.

Methods

Altogether 436 patients with CHD were recruited as cases, and meanwhile, 471 healthy volunteers were included into the control group. Besides, SNPs of GAS5/MIR‐21/mTOR axis were genotyped utilizing mass spectrometry. Chi‐square test was applied to figure out SNPs that were strongly associated with CHD risk and prognosis, and combined effects of SNPs and environmental parameters on CHD risk were evaluated through multifactor dimensionality reduction (MDR) model.

Results

Single nucleotide polymorphisms of GAS5 (ie, rs2067079 and rs6790), MIR‐21 (ie, rs1292037), and mTOR (rs2295080, rs2536, and rs1034528) were associated with susceptibility to CHD, and also Gensini score change of patients with CHD (P < .05). MDR results further demonstrated that rs2067079 and rs2536 were strongly interactive in elevating CHD risk (P < .05), while smoking, rs6790 and rs2295080 showed powerful reciprocity in predicting Gensini score change of patients with CHD (P < .05).

Conclusion

Single nucleotide polymorphisms of lncRNA GAS5/miR‐21/mTOR axis might interact with smoking to regulate CHD risk, which was conducive to diagnosis and prognostic anticipation of CHD.

Association of 584C/T polymorphism in endothelial lipase gene with risk of coronary artery disease

BACKGROUND

Coronary artery disease (CAD) is one of the cardiovascular diseases, which is caused by a reduced amount of oxygen and blood that goes to the heart. CAD includes stable angina, unstable angina, myocardial infarction, and sudden cardiac death. It is a common cause of death in both men and women. The environmental and genetic factors are involved in the development of CAD. Multiple gene polymorphisms are risk factors of CAD.

OBJECTIVE

To evaluate the association between EL 584C/T polymorphism, CAD risk, and lipid profile in an Egyptian population.

METHODS

This is a case-control study. The patients were classified into three groups: Group A: Control group, this group included 42 apparently healthy people. Group B: included 42 subjects diagnosed with previous myocardial infarction (MI). Group C: included 42 subjects diagnosed with unstable angina (UA).

RESULTS

The frequencies of TT and CT genotypes and T allele were higher in control healthy individuals than CAD patients. In addition, the risk of CAD was significantly lower in individuals carrying T allele (P = 0.001). Serum high-density lipoprotein (HDL) levels were significantly higher in healthy individuals and CAD patients (MI and UA patients) carrying EL 584 T allele compared with those carrying CC genotype (P ≤  0.001). By multiple logistic regression, we found that the protective effect of T allele remained significant (P = 0.005) and it decreased the risk of CAD independent of plasma HDL levels.

CONCLUSION

There was a significant difference between 584C/T polymorphism in the EL gene and CAD and HDL level. T-allele carriers had a higher HDL level and were protected from CAD. T allele was significantly associated with the decreased risk of CAD independent of plasma HDL levels.

LIPG SNPs, their haplotypes and gene-environment interactions on serum lipid levels

Background

Maonan nationality is a relatively conservative and isolated minority in the Southwest of China. Little is known about the association of endothelial lipase gene (LIPG) single nucleotide polymorphisms (SNPs) and serum lipid levels in the Chinese populations.

Methods

A total of 1280 subjects of Maonan nationality and 1218 participants of Han nationality were randomly selected from our previous stratified randomized samples. Genotypes of the four LIPG SNPs were determined by polymerase chain reaction-restriction fragment length polymorphism, and then confirmed by direct sequencing.

Results

Several SNPs were associated with high-density lipoprotein cholesterol (rs3813082, rs2000813 and rs2097055) in the both ethnic groups; total cholesterol and apolipoprotein (Apo) A1 (rs2000813) in Han nationality; and low-density lipoprotein cholesterol, ApoB, triglyceride (rs2097055) and ApoA1 (rs3819166) in Maonan minority (P < 0.0125 for all after Bonferroni correction). The commonest haplotype was rs3813082T-rs2000813C-rs2097055T-rs3819166A (Han, 44.2% and Maonan, 48.7%). The frequencies of the T-C-T-A, T-C-T-G, T-T-C-G and G-T-C-G haplotypes were different between the Maonan and Han populations (P < 0.05–0.001). The associations between haplotypes and dyslipidemia were also different in the Han and/or Maonan populations (P < 0.05–0.001).

Conclusions

The differences in serum lipid profiles between the two ethnic groups might partly be attributed to these LIPG SNPs, their haplotypes and gene-environmental interactions.

Trial registration

Retrospectively registered.

Investigation of the Association Between 584C/T Polymorphism of EL Gene and Risk of Premature Coronary Artery Disease in Fars Province

Introduction: Endothelial lipase (EL) is a protein from the triglyceride lipase family which plays an important role in high-density lipoprotein (HDL) metabolism. One of the most frequently studied variants is 584C/T which causes the amino acid threonine at codon 111 to convert to isoleucine. Many studies have shown the association of this variant with HDL-C level and CAD disease.

Methods: The population of this study consists of 140 patients (all males) with angiographically confirmed coronary artery disease (CAD) and 80 controls. Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) was carried out for genotyping of LIPG 584C/T. Data were analyzed using SPSS.

Results: The results of the study indicated that the frequency of T allele was significantly lower among CAD patients than among controls (0.27 vs 0.36, P = .004). However, no significant correlation was found between the 584C/T variant and serum HDL-C level. Multivariate regression analysis confirmed that the T allele is significantly associated with CAD disregarding the age, hypertension, hypercholesterolemia, diabetes and HDL-C (OR = 0.494, 95% CI = 0.253- 0.968, P =.040).

Conclusion: It was concluded that the T allele was associated with protection from CAD in Fars province independent of HDL-C level.

Association of endothelial lipase gene-384A/C with coronary artery disease in Han Chinese people

OBJECTIVES

The endothelial lipase gene (LIPG) is one of the important genes in the metabolism of high-density lipoprotein cholesterol (HDL-C) and may be involved in the pathogenesis of coronary artery disease (CAD).

MATERIALS AND METHODS

To investigate the relationship between the common single nucleotide polymorphisms (SNPs) 584C/T (rs2000813) and -384A/C (rs3813082) in the LIPG gene and CAD, allele and genotype frequencies of the two SNPs were analysed in 287 Chinese patients with CAD and 367 controls by the high-resolution melting curve (HRM) method.

RESULTS

For 584C/T, no significant difference in polymorphic distribution was observed between patients and controls. However, the frequencies of allele C (20.2% vs 15%, p=0.013, OR=1.437, 95% CI 1.078 to 1.915) at -384A/C were significantly increased in patients compared with controls. Haplotype analysis also showed that haplotype CT (12.37% vs 8.72%, p=0.035, OR=1.478, 95% CI 1.034 to 2.112) was significantly higher in patients compared with controls.

CONCLUSIONS

These results suggested that the SNP -384A/C in the LIPG gene may be associated with risk for CAD and the LIPG gene may play a role in CAD in the Han Chinese.

microRNAs and HDL life cycle

miRNAs have emerged as important regulators of lipoprotein metabolism. Work over the past few years has demonstrated that miRNAs control the expression of most of the genes associated with high-density lipoprotein (HDL) metabolism, including the ATP transporters, ABCA1 and ABCG1, and the scavenger receptor SRB1. These findings strongly suggest that miRNAs regulate HDL biogenesis, cellular cholesterol efflux, and HDL cholesterol (HDL-C) uptake in the liver, thereby controlling all of the steps of reverse cholesterol transport. Recent work in animal models has demonstrated that manipulating miRNA levels including miR-33 can increase circulating HDL-C. Importantly, antagonizing miR-33 in vivo enhances the regression and reduces the progression of atherosclerosis. These findings support the idea of developing miRNA inhibitors for the treatment of dyslipidaemia and related cardiovascular disorders such as atherosclerosis. This review article focuses on how HDL metabolism is regulated by miRNAs and how antagonizing miRNA expression could be a potential therapy for treating cardiometabolic diseases.

The associations between endothelial lipase 584C/T polymorphism and HDL-C level and coronary heart disease susceptibility: a meta-analysis

Background

Studies had investigated the relationships between endothelial lipase (EL) 584C/T polymorphism and high density lipoprotein cholesterol (HDL-C) level and coronary heart disease (CHD), but the results were controversial. To investigate a more authentic associations between EL 584C/T polymorphism and HDL-C level, and the risk of CHD, we performed this meta-analysis.

Methods

We searched electric databases for all articles on the associations between EL 584C/T polymorphism and HDL-C level, and CHD risk. Odds ratios (ORs) with 95% confidence interval (CI) were used to evaluate the strength of the association between the EL 584C/T polymorphism and the CHD susceptibility. The pooled standardized mean difference (SMD) with 95% CI was used for the meta-analysis of EL 584C/T polymorphism and HDL-C level. Begg’s funnel plots and Egger’s test were used to examine the publication bias.

Results

For CHD association, the pooled OR was 0.829 (95% CI: 0.701-0.980, P = 0.028) for the dominant model and 0.882 (95% CI: 0.779-0.999, P = 0.049) for the allelic model. By meta-regression analysis, we found that only total sample size could influence the initial heterogeneity. When the subgroup analysis was carried out, we found that the protective effect only existed in the subgroups of relatively small sample size. Sensitivity analyses indicated that Tang’s study influenced the overall results significantly. We calculated the pooled ORs again after excluding Tang’s study and found the association between EL 584C/T polymorphism and the risk of CHD was not significant for any genetic model. For HDL-C level association, the carriers of 584 T allele had a higher HDL-C level than the non-carriers. The pooled SMD was 0.399 (95% CI: 0.094-0.704, P = 0.010). When the studies were stratified by ethnicity and total sample size, the positive effects existed in the Caucasians and in subgroups of larger sample size. No significant publication bias was found in the present meta-analysis.

Conclusions

The results of the present meta-analysis suggest that the carriers of EL 584 T allele have a higher HDL-C level in Caucasian populations. Whereas, it might not be a protective factor for CHD.

Interactions of several single nucleotide polymorphisms and high body mass index on serum lipid traits

The interactions between single nucleotide polymorphisms (SNPs) and high body mass index (BMI) on serum lipid profiles are limited. This study was undertaken to detect the interactions of 10 SNPs and high BMI on serum lipid traits in an isolated population. A total of 978 normal BMI (< 24 kg/m2) and 751 high BMI (≥ 24 kg/m2) subjects of Bai Ku Yao were randomly selected from our previous stratified randomized cluster samples. Genotypes of rs2066715, rs1044925, low density lipoprotein receptor (LDL-R) Ava||, rs2070895, rs2000813, rs1801133, rs3757354, rs505151, rs2016520, and rs5888 SNPs were determined by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing. The interactions were detected by factorial design covariance analysis. The genotypic and allelic frequencies of rs2070895 and rs505151 were different between normal and high BMI subjects, the genotypic frequency of rs2000813 and allelic frequency of rs3757354 were also different between normal and high BMI subjects (P < 0.01). The levels of total cholesterol (TC), apolipoprotein (Apo) A1 (rs2066715); TC, low-density lipoprotein cholesterol (LDL-C), ApoA1, ApoB, and ApoA1/ApoB (rs2070895); triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), and ApoA1 (rs2000813); TC, HDL-C, LDL-C, ApoA1, and ApoB (rs1801133); HDL-C and ApoA1 (rs3757354) in normal BMI subjects were different among the genotypes (P < 0.01). The levels of LDL-C, ApoB, and ApoA1/ApoB (rs2066715); HDL-C, ApoA1, ApoB, and ApoA1/ApoB (rs2070895); TC, HDL-C, ApoA1, and ApoB (rs2000813); TC, TG, HDL-C, LDL-C, ApoA1, and ApoB (rs1801133); TC, TG, and ApoB (rs3757354); TG (rs505151); TG and ApoA1 and ApoB (rs2016520); and TC, HDL-C, LDL-C, ApoA1, and ApoB (rs5888) in high BMI subjects were also different among the genotypes (P < 0.01). The SNPs of rs2066715 (LDL-C and ApoA1/ApoB); rs2070895 (TC, LDL-C, ApoA1, and ApoB); rs2000813 (ApoB); rs1801133 (TC, TG, and LDL-C); rs3757354 (TC and TG); rs505151 (TG, HDL-C, ApoB, and ApoA1/ApoB); rs2016520 (TG and ApoA1/ApoB); and rs5888 (TG, ApoA1, and ApoB) interacted with high BMI to influence serum lipid levels (P < 0.01). The differences in serum lipid levels between normal and high BMI subjects might partly result from different interactions of several SNPs and high BMI.

Genetic and structure-function studies of missense mutations in human endothelial lipase

Endothelial lipase (EL) plays a pivotal role in HDL metabolism. We sought to characterize EL and its interaction with HDL as well as its natural variants genetically, functionally and structurally. We screened our biethnic population sample (n = 802) for selected missense mutations (n = 5) and identified T111I as the only common variant. Multiple linear regression analyses in Hispanic subjects revealed an unexpected association between T111I and elevated LDL-C (p-value = 0.012) and total cholesterol (p-value = 0.004). We examined lipase activity of selected missense mutants (n = 10) and found different impacts on EL function, ranging from normal to complete loss of activity. EL-HDL lipidomic analyses indicated that EL has a defined remodeling of HDL without exhaustion of the substrate and a distinct and preference for several fatty acids that are lipid mediators and known for their potent pro- and anti-inflammatory properties. Structural studies using homology modeling revealed a novel α/β motif in the C-domain, unique to EL. The EL dimer was found to have the flexibility to expand and to bind various sizes of HDL particles. The likely impact of the all known missense mutations (n = 18) on the structure of EL was examined using molecular modeling and the impact they may have on EL lipase activity using a novel structure-function slope based on their structural free energy differences. The results of this multidisciplinary approach delineated the impact of EL and its variants on HDL. Moreover, the results suggested EL to have the capacity to modulate vascular health through its role in fatty acid-based signaling pathways.

The impact of partial and complete loss-of-function mutations in endothelial lipase on high-density lipoprotein levels and functionality in humans

BACKGROUND

Endothelial lipase is a phospholipase with activity against high-density lipoprotein. Although a small number of mutations in LIPG have been described, the role of LIPG in protection against atherosclerosis is unclear.

METHODS AND RESULTS

We identified 8 loss-of-function (LOF) mutations in LIPG in individuals with high-density lipoprotein cholesterol. Functional analysis confirmed that most rare mutations abolish lipase activity in vitro, indicating complete LOF, whereas 2 more common mutations N396S and R476W reduce activity by ≈50%, indicating partial LOF and implying ≈50% and ≈75% remaining endothelial lipase function in heterozygous complete LOF and partial LOF mutation carriers, respectively. complete LOF mutation carriers had significantly higher plasma high-density lipoprotein cholesterol levels compared with partial LOF mutation carriers. Apolipoprotein B-depleted serum from complete LOF carriers showed significantly enhanced cholesterol efflux acceptor capacity, whereas only trends were observed in partial LOF carriers. Carriers of LIPG mutations exhibited trends toward reduced coronary artery disease in 4 independent cohorts (meta-analysis odds ratio, 0.7; P=0.04).

CONCLUSIONS

Our data suggest that the impact of LIPG mutations is directly related to their effect on endothelial lipase function and support that antagonism of endothelial lipase function improves cardioprotection.

ELISA system for human endothelial lipase

BACKGROUND

Endothelial lipase (EL) regulates the metabolism of HDL cholesterol (HDL-C). However, the role of EL in regulating plasma HDL-C concentrations and EL's potential involvement in atherosclerosis in humans has not been fully investigated due to the lack of reliable assays for EL mass. We developed an ELISA system for serum EL mass.

METHODS

Human recombinant EL proteins, purified from cultured media of human EL-transfected Chinese hamster ovary cells, were used as antigen and calibrator. Two specific monoclonal antibodies were generated in mice against recombinant EL protein for a sandwich ELISA. We measured EL mass in human serum using EL recombinant protein as a calibration standard.

RESULTS

The EL antibodies did not cross-react with lipoprotein lipase and hepatic triglyceride lipase. The detection limit of the ELISA was 20 pg/mL, which is approximately 10 times lower than that of previous ELISA systems. Recovery of spiked EL in serum was 90%-105%. Assay linearity was intact with a >4-fold dilution of serum. Intra- and interassay CVs were <5%. The serum EL mass in 645 human subjects was [mean (SE)] 344.4 (7.7) pg/mL (range 55.2-1387.7 pg/mL). Interestingly, serum EL mass was increased in patients with diagnosed cardiovascular disease and inversely correlated with serum HDL-C concentrations. There was no difference in EL mass between pre- and postheparin plasma samples.

CONCLUSIONS

This ELISA should be useful for clarifying the impact of EL on HDL metabolism and EL's potential role in atherosclerosis.

Several genetic polymorphisms interact with overweight/obesity to influence serum lipid levels

Background

Information about the interactions of single nucleotide polymorphisms (SNPs) and overweight/obesity on serum lipid profiles is still scarce. The present study was undertaken to detect ten SNPs and their interactions with overweight/obesity on serum lipid levels.

Methods

A total of 978 normal weight and 751 overweight/obese subjects of Bai Ku Yao were randomly selected from our previous stratified randomized cluster samples. Normal weight, overweight and obesity were defined as a body mass index (BMI) < 24, 24–28, and > 28 kg/m²; respectively. Serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), apolipoprotein (Apo) A1 and ApoB levels were measured. Genotyping of ATP-binding cassette transporter A1 (ABCA-1) V825I, acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) rs1044925, low density lipoprotein receptor (LDL-R) AvaII, hepatic lipase gene (LIPC) -250G>A, endothelial lipase gene (LIPG) 584C>T, methylenetetrahydrofolate reductase (MTHFR) 677C>T, the E3 ubiquitin ligase myosin regulatory light chain-interacting protein (MYLIP) rs3757354, proprotein convertase subtilisin-like kexin type 9 (PCSK9) E670G, peroxisome proliferator-activated receptor delta (PPARD) +294T>C, and Scavenger receptor class B type 1 (SCARB1) rs5888 was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing. The interactions were detected by factorial design covariance analysis.

Results

The genotypic and allelic frequencies of LIPC and PCSK9 were different between normal weight and overweight/obese subjects, the genotypic frequency of LIPG and allelic frequency of MYLIP were also different between normal weight and overweight/obese subjects (P < 0.05-0.001). The levels of TC, ApoA1 (ABCA-1); TC, LDL-C, ApoA1, ApoB and ApoA1/ApoB (LIPC); TG, HDL-C, and ApoA1 (LIPG); TC, HDL-C, LDL-C, ApoA1 and ApoB (MTHFR); HDL-C and ApoA1 (MYLIP) in normal weight subjects were different among the genotypes (P < 0.01-0.001). The levels of LDL-C, ApoB and ApoA1/ApoB (ABCA-1); HDL-C, ApoA1, ApoB and ApoA1/ApoB (LIPC); TC, HDL-C, ApoA1 and ApoB (LIPG); TC, TG, HDL-C, LDL-C, ApoA1 and ApoB (MTHFR); TC, TG and ApoB (MYLIP); TG (PCSK9); TG, ApoA1 and ApoB (PPARD); and TC, HDL-C, LDL-C, ApoA1 and ApoB (SCARB1) in overweight/obese subjects were different among the genotypes (P < 0.01-0.001). The SNPs of ABCA-1 (LDL-C and ApoA1/ApoB); LIPC (TC, LDL-C, ApoA1 and ApoB); LIPG (ApoB); MTHFR (TC, TG and LDL-C); MYLIP (TC and TG); PCSK9 (TG, HDL-C, ApoB and ApoA1/ApoB); PPARD (TG and ApoA1/ApoB); and SCARB1 (TG, ApoA1 and ApoB) interacted with overweight/obesity to influence serum lipid levels (P < 0.05-0.001).

Conclusions

The differences in serum lipid levels between normal weight and overweight/obese subjects might partly result from different genetic polymorphisms and the interactions between several SNPs and overweight/obesity.

Association of several lipid-related gene polymorphisms and blood pressure variation in the Bai Ku Yao population

BACKGROUND

Sex differences in hypertension are not well known. The present study was undertaken to detect the association of nine lipid-related gene polymorphisms and blood pressure variation beween men and women in the Bai Ku Yao population.

METHODS

Genotyping of ATP-binding cassette transporter A1 (ABCA-1) V825I, acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) rs1044925, low-density lipoprotein receptor (LDL-R) AvaII, hepatic lipase gene (LIPC) -250G>A, endothelial lipase gene (LIPG) 584C>T, methylenetetrahydrofolate reductase (MTHFR) 677C>T, proprotein convertase subtilisin-like kexin type 9 (PCSK9) E670G, peroxisome proliferator-activated receptor delta (PPARD) +294T>C, and Scavenger receptor class B type 1 (SCARB1) rs5888 was performed in 682 normotensives and 670 hypertensives.

RESULTS

The genotypic frequencies of LDL-R and SCARB1 in normotensives and ABCA-1, ACAT-1, LDL-R, LIPC, and MTHFR in hypertensives were different between males and females (P < 0.05-0.001). The genotypic frequencies of ABCA-1, ACAT-1, LDL-R, LIPC, MTHFR, PPARD, and SCARB1 in males and ABCA-1, LDL-R, LIPC, LIPG, and MTHFR in females were different between normotensives and hypertensives (P < 0.05-0.001). Systolic blood pressure (SBP) levels in male hypertensives were different among the LIPC, LIPG, PCSK9, and SCARB1 genotypes (P < 0.05-0.01); and diastolic blood pressure (DBP) levels were different among the ABCA-1, LDL-R, LIPC, LIPG, MTHFR, PCSK9, and PPARD genotypes (P < 0.05-0.001). SBP levels in female hypertensives were different among the LIPC, MTHFR, PCSK9, and PPARD genotypes (P < 0.05-0.01); and DBP levels were different among ABCA-1, ACAT-1, MTHFR, PCSK9, PPARD, and SCARB1 genotypes (P <0.05-0.001). The correlations between these polymorphisms and blood pressure levels were also observed.

CONCLUSIONS

Sex differences in blood pressure levels in this population may partly attribute to the differences in some lipid-related gene polymorphisms.

The association between endothelial lipase -384A/C gene polymorphism and acute coronary syndrome in a Chinese population

Endothelial lipase (EL) is a novel member of the triglyceride (TG) lipase family. A growing body of evidence has indicated that EL gene polymorphism might contribute to the process of cardiovascular diseases. This study was aimed to reveal the potential relationship between EL -384A/C gene polymorphism and acute coronary syndrome (ACS) in a Chinese Han population. The subjects were composed of 320 ACS patients and 315 age- and gender- matched controls. We detected the EL -384A/C genotypes and allele frequencies by using polymerase chain reaction-restriction fragment length polymorphism analysis. There was significant difference in AA genotype and AC+CC genotype between ACS and control groups (P = 0.014). The A allele frequency was significantly higher in ACS group than in control group (87.8 vs 83.8 %, P = 0.041). The relationship between the variant and ACS remained significant after adjusting for current smoker, hypertension, diabetes mellitus, total cholesterol and TG (OR = 0.682, 95 % CI = 0.472-0.986). The levels of HDL and ApoA-I were significantly higher in AC+CC genotype than in AA genotype (HDL: 1.20 ± 0.35 vs 1.11 ± 0.29 mmol/L, P = 0.001; ApoA-I: 1.14 ± 0.25 vs 1.08 ± 0.21 g/L, P = 0.009). We found that the EL -384A/C gene polymorphism might be associated with ACS in Chinese Han population, suggesting that the variant might be involved in the pathogenesis of ACS.

Population-Based Resequencing of LIPG and ZNF202 Genes in Subjects with Extreme HDL Levels

Endothelial lipase (LIPG) and zinc finger protein 202 (ZNF202) are two pivotal genes in high density lipoprotein (HDL metabolism). We sought to determine their genetic contribution to variation in HDL-cholesterol levels by comprehensive resequencing of both genes in 235 individuals with high or low HDL-C levels. The selected subjects were 141 Whites (High HDL Group: n = 68, [Formula: see text] Low HDL Group: n = 73, [Formula: see text]) and 94 Hispanics (High HDL Group: n = 46, [Formula: see text] Low HDL Group: n = 48, [Formula: see text]). We identified a total of 185 and 122 sequence variants in LIPG and ZNF202, respectively. We found only two missense variants in LIPG (T111I and N396S) and two in ZNF202 (A154V and K259E). In both genes, there were several variants unique to either the low or high HDL group. For LIPG, the proportion of unique variants differed between the high and low HDL groups in both Whites (p = 0.022) and Hispanics (p = 0.017), but for ZNF202 this difference was observed only in Hispanics (p = 0.021). We also identified a common haplotype in ZNF202 among Whites that was significantly associated with the high HDL group (p = 0.013). These findings provide insights into the genetics of LIPG and ZNF202, and suggest that sequence variants occurring with high frequency in non-exonic regions may play a prominent role in modulating HDL-C levels in the general population.

Interactions of the LIPG 584C>T polymorphism and alcohol consumption on serum lipid levels

Both endothelial lipase gene (LIPG) 584C>T (rs2000813) polymorphism and alcohol consumption modulate serum lipid levels. But their interactions on serum lipid profiles are not well known. The present study was undertaken to detect the interactions of LIPG 584C>T polymorphism and alcohol consumption on serum lipid levels. Genotyping of the LIPG 584C>T was performed in 763 unrelated nondrinkers and 520 drinkers aged 15-85 years. The levels of serum total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (Apo) AI, and the ratio of ApoAI to ApoB were higher in drinkers than in nondrinkers (P<.01 for all). There were no significant differences in the genotypic and allelic frequencies between nondrinkers and drinkers. The levels of TC, HDL-C, and ApoAI in nondrinkers were different among the three genotypes (P<.05-.01), the subjects with CT genotype had higher TC, HDL-C, and ApoAI levels than the subjects with CC genotype. The levels of HDL-C and ApoAI in drinkers were different among the three genotypes (P<.001 and P<.05; respectively), the individuals with TT genotype had higher HDL-C and ApoAI levels than the individuals with CT and CC genotypes. The interactions between LIPG 584C>T genotypes and alcohol consumption on serum HDL-C (P<.01) and ApoAI levels (P<.05) were also detected by using a factorial regression analysis after controlling for potential confounders. The levels of TC in nondrinkers were correlated with LIPG 584C>T alleles (P<.05), whereas the levels of TG and HDL-C were associated with LIPG 584C>T alleles (P<.05) and genotypes (P<.05), respectively. These results suggest that the subjects with TT genotype benefit more from alcohol consumption than the subjects with CT and CC genotypes in increasing serum HDL-C and ApoAI levels.

Role of hepatic lipase and endothelial lipase in high-density lipoprotein-mediated reverse cholesterol transport

Reverse cholesterol transport (RCT) constitutes a key part of the atheroprotective properties of high-density lipoproteins (HDL). Hepatic lipase (HL) and endothelial lipase (EL) are negative regulators of plasma HDL cholesterol levels. Although overexpression of EL decreases overall macrophage-to-feces RCT, knockout of both HL and EL leaves RCT essentially unaffected. With respect to important individual steps of RCT, current data on the role of EL and HL in cholesterol efflux are not conclusive. Both enzymes increase hepatic selective cholesterol uptake; however, this does not translate into altered biliary cholesterol secretion, which is regarded the final step of RCT. Also, the impact of HL and EL on atherosclerosis is not clear cut; rather it depends on respective experimental conditions and chosen models. More mechanistic insights into the diverse biological properties of these enzymes are therefore required to firmly establish EL and HL as targets for the treatment of atherosclerotic cardiovascular disease.

Association of the LIPG 584C > T polymorphism and serum lipid levels in the Guangxi Bai Ku Yao and Han populations

BACKGROUND

Endothelial lipase (EL) is a major determinant of high-density lipoprotein-cholesterol (HDL-C) metabolism, but the association of endothelial lipase gene (LIPG) polymorphism and serum HDL-C levels is scarce and conflicting in diverse populations. Bai Ku Yao is an isolated subgroup of the Yao minority in China. This study was designed to detect the association of LIPG 584C > T (rs2000813) polymorphism and several environmental factors with serum lipid levels in the Guangxi Bai Ku Yao and Han populations.

METHODS

A total of 645 subjects of Bai Ku Yao and 638 participants of Han Chinese were randomly selected from our previous stratified randomized cluster samples. Genotyping of the LIPG 584C > T was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing.

RESULTS

The levels of serum total cholesterol (TC), HDL-C, low-density lipoprotein cholesterol (LDL-C) and apolipoprotein (Apo) AI and ApoB were lower in Bai Ku Yao than in Han (P < 0.05 - 0.001). The frequency of C and T alleles was 73.5% and 26.5% in Bai Ku Yao, and 67.9% and 32.1% in Han (P < 0.01); respectively. The frequency of CC, CT and TT genotypes was 50.4%, 46.2% and 3.4% in Bai Ku Yao, and 41.4%, 53.1% and 5.5% in Han (P < 0.01); respectively. Serum HDL-C levels in both ethnic groups were different among the three genotypes (P < 0.05 for each). Serum TC levels in both ethnic groups were also different between the CC and CT/TT genotypes (P < 0.05 for each). The T allele carriers had higher serum HDL-C and TC levels than the T allele noncarriers. Multivariate logistic regression analysis showed that the levels of HDL-C and ApoB were correlated with genotypes in Bai Ku Yao (P < 0.05 for each), whereas the levels of TC and HDL-C were associated with genotypes in Han Chinese (P < 0.05 and P < 0.01). Serum lipid parameters were also correlated with several environmental factors in the both ethnic groups.

CONCLUSIONS

The frequency of LIPG 584T allele is lower in Bai Ku Yao than in Han Chinese. The LIPG 584T allele is associated with increased serum HDL-C, TC and ApoB levels. The differences in serum HDL-C, TC and ApoB levels between the two ethnic groups might partly result from different genotypic and allelic frequencies of LIPG 584C > T or different LIPG-enviromental interactions.

Role of endothelial lipase in atherosclerosis

Endothelial lipase, which is a newly identified member of the lipase family, plays an important role in high-density lipoprotein metabolism, which catalyzes the hydrolysis of high-density lipoprotein phospholipids and facilitates the clearance of high-density lipoprotein from the circulation. In addition, inflammatory cytokines, including tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1beta), upregulate endothelial lipase expression, and endothelial lipase also affects the expression of cytokines, which in turn play an important role in atherogenesis. Endothelial lipase expression has been associated with macrophages within human atherosclerotic lesions. However, an important challenge is to determine how endothelial lipase alters the progression of atherosclerosis. Although few data are available from human studies, it seems that plasma endothelial lipase levels in individuals with atherosclerosis might be higher than that measured in healthy individuals. Therefore, we believe that endothelial lipase might be a promising marker for atherosclerosis in clinical settings in the future.

The T111I variant in the endothelial lipase gene and risk of coronary heart disease in three independent populations

AIMS

Endothelial lipase (LIPG) is implicated in the metabolism of high-density lipoprotein cholesterol (HDL-C). Small studies in selected populations have reported higher HDL-C levels among carriers of the common T111I variant in LIPG, but whether this variant is associated with plasma lipids and risk of coronary heart disease (CHD) in the general population is unclear. The objective of this study was to address the associations of the T111I variant with plasma lipids and risk of CHD in three independent prospective studies of generally healthy men and women.

METHODS AND RESULTS

The T111I variant was genotyped in case-control studies of CHD nested within the Diet, Cancer, and Health study with 998 cases, Nurses' Health Study with 241 cases, and Health Professionals Follow-up Study with 262 cases. The minor allele frequency in the combined pool of controls was 0.29. The T111I variant was not associated with HDL-C or any other lipid and lipoprotein measures. Compared with wildtype homozygotes, the pooled estimate for risk of CHD was 0.95 (0.85-1.06) per T111I allele.

CONCLUSION

Our analysis among healthy Caucasian men and women from three independent studies does not support an association between the T111I variant and HDL-C, other plasma lipids, or risk of CHD.

Identification of genetic markers associated with high-density lipoprotein-cholesterol by genome-wide screening in a Japanese population: the Suita study

BACKGROUND

Recent genome-wide association studies (GWAS) have identified genes or loci affecting lipid levels. Given the difference in allele frequencies and linkage disequilibrium patterns across the populations, a GWAS was conducted using the Illumina 550K in a Japanese population (n=900) in search of population-specific genetic variations associated with high-density lipoprotein (HDL)-cholesterol.

METHODS AND RESULTS

Among the 368,274 single nucleotide polymorphisms (SNPs) with a minor allele frequency of at least 0.1, 43 SNPs exceeded the arbitrary threshold of -log(10)P >4.0. The most significant SNP was rs3764261, located 5'upstream of CETP, exhibiting a -log(10)P value of 6.17. Increasing the sample size by genotyping in the additional Suita sample (n=1,810) further improved the level of significance, with each additional copy of the minor allele being associated with an increase in HDL-cholesterol by 6.2 mg/dl (P =3.4x10(-12)). Interestingly, the minor allele was more prevalent in cases with myocardial infarction than in controls (0.221 vs 0.196, nominal P=0.02).

CONCLUSIONS

The association between genetic variants at CETP and HDL-cholesterol was replicated in our sample. None of the genetic variants exerted a greater influence on HDL levels than those at CETP. Associations for the top-ranked SNPs need to be tested for further replication in an independent sample.

Loss-of-function variants in endothelial lipase are a cause of elevated HDL cholesterol in humans

Elevated plasma concentrations of HDL cholesterol (HDL-C) are associated with protection from atherosclerotic cardiovascular disease. Animal models indicate that decreased expression of endothelial lipase (LIPG) is inversely associated with HDL-C levels, and genome-wide association studies have identified LIPG variants as being associated with HDL-C levels in humans. We hypothesized that loss-of-function mutations in LIPG may result in elevated HDL-C and therefore performed deep resequencing of LIPG exons in cases with elevated HDL-C levels and controls with decreased HDL-C levels. We identified a significant excess of nonsynonymous LIPG variants unique to cases with elevated HDL-C. In vitro lipase activity assays demonstrated that these variants significantly decreased endothelial lipase activity. In addition, a meta-analysis across 5 cohorts demonstrated that the low-frequency Asn396Ser variant is significantly associated with increased HDL-C, while the common Thr111Ile variant is not. Functional analysis confirmed that the Asn396Ser variant has significantly decreased lipase activity both in vitro and in vivo, while the Thr111Ile variant has normal lipase activity. Our results establish that loss-of-function mutations in LIPG lead to increased HDL-C levels and support the idea that inhibition of endothelial lipase may be an effective mechanism to raise HDL-C.

Heritability and linkage study on heart rates in a Mongolian population

Elevated heart rate has been proposed as an independent risk factor for cardiovascular diseases, but their interrelationships are not well understood. In this study, we performed a genome-wide linkage scan in 1,026 individuals (mean age 30.6 years, 54.5% women) from 73 extended families of Mongolia and determined quantitative trait loci that influence heart rate. The DNA samples were genotyped using deCODE 1,039 microsatellite markers for 3 cM density genome-wide linkage scan. Correlation analysis was carried out to evaluate the correlation of the covariates and the heart rate. T-tests of the heart rate were also performed on sex, smoking and alcohol intake. Consequently, this model was used in a nonparametric genome-wide linkage analysis using variance component model to create a multipoint logarithm of odds (LOD) score and a corresponding P value. In the adjusted model, the heritability of heart rate was estimated as 0.32 (P<.0001) and a maximum multipoint LOD score of 2.03 was observed in 77 cM region at chromosome 18. The second largest LOD score of 1.52 was seen on chromosome 5 at 216 cM. Genes located on the specified locations in chromosomes 5 and 18 may be involved in the regulation of heart rate.

Protective effect of an endothelial lipase gene variant on coronary artery disease in a Chinese population

The aim of the present study was to assess the influence of the endothelial lipase (EL) gene 584C/T variant, which results in a change at codon 111 of the EL gene from threonine to isoleucine, on the risk of coronary artery disease (CAD) in a Chinese population. The study population consisted of 265 CAD patients and 265 age- and sex-matched control subjects. The T allele frequency was significantly lower among CAD patients than among control subjects (18.3% vs. 29.8%; P < 0.001). In both the CAD and control groups, the T allele carriers had higher high density lipoprotein cholesterol (HDL-C) levels than homozygote C allele carriers. In a multiple logistic regression model adjusted for age, sex, body mass index, smoking, hypertension, diabetes, hyperlipidemia, and low density lipoprotein cholesterol, a significantly decreased risk of developing CAD was found in subjects carrying a variant CT or TT genotype (odds ratio = 0.496, 95% confidence interval = 0.341-0.723; P < 0.001), and the significance persisted after further adjustment for HDL-C. In conclusion, our observation that the EL 584T allele was associated with protection from CAD in this Chinese population replicates the findings in a Japanese study, which found a similar association of this allele with acute myocardial infarction, independent of HDL-C levels.