Plasma activity of endothelial lipase impacts high-density lipoprotein metabolism and coronary risk factors in humans

Multivessel Coronary Artery Disease Complicated by Diabetes Mellitus Has a Relatively Small Effect on Endothelial and Lipoprotein Lipases Expression in the Human Atrial Myocardium and Coronary Perivascular Adipose Tissue

Endothelial (EL) and lipoprotein (LPL) lipases are enzymes involved in lipoproteins metabolism and formation of atherosclerosis, a pathological feature of coronary artery disease (CAD). This paper examines the role of the lipases in the right atrial appendage (RAA) and coronary perivascular adipose tissue (PVAT) of patients with CAD alone or with accompanying diabetes. Additionally, correlation analysis for plasma concentration of the lipases, apolipoproteins (ApoA-ApoJ) and blood lipids (Chol, HDL-C, LDL-C, TAG) was performed. We observed that CAD had little effect on the lipases gene/protein levels in the RAA, while their transcript content was elevated in the PVAT of diabetic CAD patients. Interestingly, the RAA was characterized by higher expression of EL/LPL (EL: +1-fold for mRNA, +5-fold for protein; LPL: +2.8-fold for mRNA, +12-fold for protein) compared to PVAT. Furthermore, ApoA1 plasma concentration was decreased, whereas ApoC1 and ApoH were increased in the patients with CAD and/or diabetes. The concentrations of ApoC3 and ApoD were strongly positively correlated with TAG content in the blood, and the same was true for ApoB with respect to LDL-C and total cholesterol. Although plasma concentrations of EL/LPL were elevated in the patients with diabetes, CAD alone had little effect on blood, myocardial and perivascular fat expression of the lipases.

Blocking endothelial lipase with monoclonal antibody MEDI5884 durably increases high density lipoprotein in nonhuman primates and in a phase 1 trial

Cardiovascular disease (CVD) is the leading global cause of death, and treatments that further reduce CV risk remain an unmet medical need. Epidemiological studies have consistently identified low high-density lipoprotein cholesterol (HDL-C) as an independent risk factor for CVD, making HDL elevation a potential clinical target for improved CVD resolution. Endothelial lipase (EL) is a circulating enzyme that regulates HDL turnover by hydrolyzing HDL phospholipids and driving HDL particle clearance. Using MEDI5884, a first-in-class, EL-neutralizing, monoclonal antibody, we tested the hypothesis that pharmacological inhibition of EL would increase HDL-C by enhancing HDL stability. In nonhuman primates, MEDI5884 treatment resulted in lasting, dose-dependent elevations in HDL-C and circulating phospholipids, confirming the mechanism of EL action. We then showed that a favorable lipoprotein profile of elevated HDL-C and reduced low-density lipoprotein cholesterol (LDL-C) could be achieved by combining MEDI5884 with a PCSK9 inhibitor. Last, when tested in healthy human volunteers, MEDI5884 not only raised HDL-C but also increased HDL particle numbers and average HDL size while enhancing HDL functionality, reinforcing EL neutralization as a viable clinical approach aimed at reducing CV risk.

Treadmill Running Changes Endothelial Lipase Expression: Insights from Gene and Protein Analysis in Various Striated Muscle Tissues and Serum

Endothelial lipase (EL) is an enzyme capable of HDL phospholipids hydrolysis. Its action leads to a reduction in the serum high-density lipoprotein concentration, and thus, it exerts a pro-atherogenic effect. This study examines the impact of a single bout exercise on the gene and protein expression of the EL in skeletal muscles composed of different fiber types (the soleus—mainly type I, the red gastrocnemius—mostly IIA, and the white gastrocnemius—predominantly IIX fibers), as well as the diaphragm, and the heart. Wistar rats were subjected to a treadmill run: (1) t = 30 [min], V = 18 [m/min]; (2) t = 30 [min], V = 28 [m/min]; (3) t = 120 [min], V = 18 [m/min] (designated: M30, F30, and M120, respectively). We established EL expression in the total muscle homogenates in sedentary animals. Resting values could be ordered with the decreasing EL protein expression as follows: endothelium of left ventricle > diaphragm > red gastrocnemius > right ventricle > soleus > white gastrocnemius. Furthermore, we observed that even a single bout of exercise was capable of inducing changes in the mRNA and protein level of EL, with a clearer pattern observed for the former. After 30 min of running at either exercise intensity, the expression of EL transcript in all the cardiovascular components of muscles tested, except the soleus, was reduced in comparison to the respective sedentary control. The protein content of EL varied with the intensity and/or duration of the run in the studied whole tissue homogenates. The observed differences between EL expression in vascular beds of muscles may indicate the muscle-specific role of the lipase.

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.

Endothelial Lipase Exerts its Anti-Atherogenic Effect through Increased Catabolism of β-VLDLs

Aim: Endothelial lipase (EL) plays an important role in lipoprotein metabolism. Our recent study showed that increased hepatic expression of EL attenuates diet-induced hypercholesterolemia, thus subsequently reducing atherosclerosis in transgenic (Tg) rabbits. However, it is yet to be determined whether increased EL activity itself per se is anti-atherogenic or whether the anti-atherogenic effect of EL is exclusively dependent on its lipid-lowering effect.

Methods: To determine the mechanisms underlying EL-mediated anti-atherogenic effect, we fed Tg and non-Tg rabbits diets containing different amounts of cholesterol to make their plasma cholesterol levels similarly high. Sixteen weeks later, we examined their lipoprotein profiles and compared their susceptibility to atherosclerosis.

Results: With Tg and non-Tg rabbits having hypercholesterolemia, the plasma lipids and lipoprotein profiles were observed to be similar, while pathological examinations revealed that lesion areas of both aortic and coronary atherosclerosis of Tg rabbits were not significantly different from non-Tg rabbits. Moreover, Tg rabbits exhibited faster clearance of DiI-labeled β-VLDLs than non-Tg rabbits.

Conclusion: The results of our study suggest that the enhancement of β-VLDL catabolism is the major mechanism for atheroprotective effects of EL in Tg rabbits.

Serum concentration of full-length- and carboxy-terminal fragments of endothelial lipase predicts future cardiovascular risks in patients with coronary artery disease

BACKGROUND

Endothelial lipase (EL), a regulator of plasma high-density lipoprotein cholesterol (HDL-C), is secreted as a 68-kDa mature glycoprotein, and then cleaved by proprotein convertases. However, the clinical significance of the circulating EL fragments remains unclear.

OBJECTIVE

The objective of this study was to analyze the impact of serum EL fragments on HDL-C levels and major adverse cardiovascular events (MACE).

METHODS

Using novel monoclonal antibodies (RC3A6) against carboxy-terminal EL protein, we have established a new enzyme-linked immunosorbent assay (ELISA) system, which can detect both full-length EL protein (full EL) and carboxy-terminal truncated fragments (total EL) in serum. The previous sandwich ELISA detected only full EL. The full and total EL mass were measured in 556 patients with coronary artery disease. Among them, 272 patients who underwent coronary intervention were monitored for 2 years for MACE.

RESULTS

There was a significant correlation between serum full and total EL mass (R = 0.45, P < .0001). However, the total EL mass showed a stronger inverse correlation with serum HDL-cholesterol concentration than the full EL mass (R = -0.17 vs -0.02). Kaplan-Meier analysis documented an association of serum total EL mass and MACE (log-rank P = .037). When an optimal cutoff value was set at 96.23 ng/mL, total EL mass was an independent prognostic factor for MACE in the Cox proportional hazard model (HR; 1.75, 95% CI; 1.10-2.79, P = .018).

CONCLUSION

Serum total EL mass could be a predictor for MACE in patients with coronary artery disease. This novel ELISA will be useful for further clarifying the impact of EL on HDL metabolism and atherosclerosis.

Assessment of HDL Cholesterol Removal Capacity: Toward Clinical Application

While there is a controversy regarding the causal relationship between high-density lipoprotein cholesterol (HDL-C) and cardiovascular disease (CVD), recent studies have demonstrated that the cholesterol efflux capacity (CEC) of HDL is associated with the incidence of CVD. However, there are several limitations to current assays of CEC. First, CEC measurements are not instantly applicable in clinical settings, because CEC assay methods require radiolabeled cholesterol and cultured cells, and these procedures are time consuming. Second, techniques to measure CEC are not standardized. Third, the condition of endogenous cholesterol donors would not be accounted for in the CEC assays. Recently, we established a simple, high-throughput, cell-free assay system to evaluate the capacity of HDL to accept additional cholesterol, which is herein referred to as "cholesterol uptake capacity (CUC)". We demonstrated that CUC represents a residual cardiovascular risk in patients with optimal low-density lipoprotein cholesterol control independently of traditional risk factors, including HDL-C. Establishing reproducible approaches for the cholesterol removal capacity of HDL is required to validate the impact of dysfunctional HDL on cardiovascular risk stratification in the "real world".

Serum Triglyceride Lipase Concentrations are Independent Risk Factors for Coronary Artery Disease and In-Stent Restenosis

Aim: Endothelial lipase (EL), hepatic lipase (HL), and lipoprotein lipase (LPL) are all triglyceride lipases and are associated with coronary artery disease (CAD). However, whether they can be simultaneous independent risk factors for CAD is unknown. In the present study, we investigated whether the three lipases can be independent risk factors simultaneously for CAD and whether combining these lipases could provide greater predictive power than high-density lipoprotein cholesterol (HDL-c) for the development of CAD.

Methods: Eighty-six patients with CAD and 65 healthy controls were enrolled in the study. Additionally, 38 patients who underwent one-year follow-up angiography after percutaneous coronary intervention with stent implantation were collected to investigate in-stent restenosis. Serum EL, HL, and LPL concentrations were measured and compared with other coronary risk factors.

Results: Serum EL and HL concentrations were both significantly increased in patients with CAD or in-stent restenosis, whereas serum LPL concentration was reduced significantly in patients with CAD. Multivariate logistic regression analysis indicated that the three lipases were simultaneous independent risk factors for CAD. However, only serum EL concentration was considered an independent risk factor for in-stent restenosis. Importantly, the receiver operating characteristic curve showed that the combined measurement of the three lipases displayed better predictive power than HDL-c or any one of the three lipases for CAD.

Conclusions: Serum EL concentration was an independent risk factor for both CAD and in-stent restenosis. Moreover, the combined assessment of serum EL, HL, and LPL concentrations as multiple risk factors provided potent predictive power for CAD.

Increased Hepatic Expression of Endothelial Lipase Inhibits Cholesterol Diet-Induced Hypercholesterolemia and Atherosclerosis in Transgenic Rabbits

OBJECTIVE

Endothelial lipase (EL) is a key determinant in plasma high-density lipoprotein-cholesterol. However, functional roles of EL on the development of atherosclerosis have not been clarified. We investigated whether hepatic expression of EL affects plasma lipoprotein metabolism and cholesterol diet-induced atherosclerosis.

APPROACH AND RESULTS

We generated transgenic (Tg) rabbits expressing the human EL gene in the liver and then examined the effects of EL expression on plasma lipids and lipoproteins and compared the susceptibility of Tg rabbits with cholesterol diet-induced atherosclerosis with non-Tg littermates. On a chow diet, hepatic expression of human EL in Tg rabbits led to remarkable reductions in plasma levels of total cholesterol, phospholipids, and high-density lipoprotein-cholesterol compared with non-Tg controls. On a cholesterol-rich diet for 16 weeks, Tg rabbits exhibited significantly lower hypercholesterolemia and less atherosclerosis than non-Tg littermates. In Tg rabbits, gross lesion area of aortic atherosclerosis was reduced by 52%, and the lesions were characterized by fewer macrophages and smooth muscle cells compared with non-Tg littermates.

CONCLUSIONS

Increased hepatic expression of EL attenuates cholesterol diet-induced hypercholesterolemia and protects against atherosclerosis.

Associations of Rs3744841 and Rs3744843 Polymorphisms in Endothelial Lipase Gene with Risk of Coronary Artery Disease and Lipid Levels in a Chinese Population

Objective

The aim of the present study was to assess the association between the 2037T/C and 2237G/A polymorphisms in the EL gene and the risk of CAD and lipid levels in a Chinese population.

Methods

A case-control study including 706 patients with CAD and 315 controls was performed. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method was used to identify the genotypes.

Results

The EL 2037 T/C polymorphism was associated with CAD risk and HDL-C levels. No significant differences were found between the EL 2237 G/A genotypes and CAD risk and lipid levels in the whole population. However, carriers of the 2237 A allele had higher Apo A1 levels than those with the 2237 GG genotype and in the CAD subgroup (P = 0.044). The CAD cases have a significantly lower frequency of the C-G haplotypes than the controls, and the T-A haplotype was significantly more common in the CAD patients than in the controls.

Conclusions

Our study concluded that the EL 2037 T/C polymorphism was associated with CAD risk and HDL-C levels, and that the C allele might be a protective factor against CAD in the Chinese Han population. In addition, the EL 2237 A allele might be associated with an increased Apo A1 level in CAD subjects.

Endothelial lipase genetic polymorphisms and the lipid-lowering response in patients with coronary artery disease on rosuvastatin

Background

Endothelial lipase (EL) plays an important role in the regulation of lipid metabolism by reducing the high density lipoprotein cholesterol (HDL-C) levels and inducing the macrophages to take up native low density lipoprotein cholesterol (LDL-C). Our purpose was to investigate the impact of EL genetic polymorphisms on the lipid-lowering effects of rosuvastatin in Chinese coronary artery disease (CAD) patients.

Methods

One hundred twenty-one unrelated CAD patients, who underwent the treatment with rosuvastatin (10mg/day) for four to eight weeks, were enrolled in this study. Before and after treatment, serum lipids levels were measured. Genotypes of EL 2037T/C and 2237 G/A polymorphisms were detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

Results

Patients with EL 2037C allele (CC + CT) had significantly lower LDL-C levels than those with TT genotype (CC + CT: 2.60 ± 0.74 mmol/l; TT: 2.90 ± 0.87 mmol/l; P = 0.047), before rosuvastatin treatment. No significant differences between baseline lipid levels and the EL 2237G/A genotypes were observed. After treatment with rosuvastatin, total cholesterol (TC), high triglyceride (TG) and LDL-C levels decreased from baseline, on average, by 23.09 % (4.59 ± 0.96 mmol/l to 3.47 ± 0.83 mmol/l), 6.36 % (2.01 ± 1.18 mmol/l to 1.68 ± 1.16 mmol/l), 32.48 % (2.77 ± 0.83 mmol/l to 1.79 ± 0.62 mmol/l), respectively (all P < 0.05) in all patients. While changes in HDL-C levels did not reach statistical significance. No significant effects of EL 2037T/C or 2237G/A polymorphism were observed on lipid-lowering effects of rosuvastatin.

Conclusions

EL 2037T/C and 2237 G/A polymorphisms might not affect the lipid-owing effects of rosuvastatin in Chinese CAD patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-016-0295-3) contains supplementary material, which is available to authorized users.

Synthetic phospholipids as specific substrates for plasma endothelial lipase

We designed and prepared synthetic phospholipids that generate lyso-phosphatidylcholine products with a unique mass for convenient detection by LC-MS in complex biological matrices. We demonstrated that compound 4, formulated either as a Triton X-100 emulsion or incorporated in synthetic HDL particles can serve as a substrate for plasma EL with useful specificity.

Hepatic Lipase: a Comprehensive View of its Role on Plasma Lipid and Lipoprotein Metabolism

Hepatic lipase (HL) is a key enzyme catalyzing the hydrolysis of triglycerides (TG) and phospholipids (PLs) in several lipoproteins. It is generally recognized that HL is involved in the remodeling of remnant, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and the production of small, dense low-density lipoproteins (sd-LDLs).On the other hand, it is unclear whether HL accelerates or retards atherosclerosis. From the clinical point of view, HL deficiency may provide useful information on answering this question, but the rarity of this disease makes it impossible to conduct epidemiological study.In this review, we describe a comprehensive and updated view of the clinical significance of HL on lipid and lipoprotein metabolism.

The relationship between serum 25-hydroxyvitamin D concentration, cardiorespiratory fitness, and insulin resistance in Japanese men

Here, we aim to investigate the independent and combined associations of serum 25-hydroxyvitamin D (25(OH)D) and cardiorespiratory fitness (CRF) with glucose metabolism. Fasting blood samples of 107 men aged 40–79 years were analyzed for 25(OH)D, glucose, insulin, glycated hemoglobin, and lipid profile. Homeostasis model assessment of insulin resistance index (HOMA-IR) was calculated from the fasting concentrations of glucose and insulin. Visceral fat area (VFA) was determined by magnetic resonance imaging and CRF by measuring maximal oxygen uptake. Median 25(OH)D concentration was 36.3 nmol/L, while the prevalence of 25(OH)D deficiency was 74.8%. Participants with high CRF had significantly lower HOMA-IR, glycated hemoglobin, and insulin values than participants with low CRF (p < 0.05). Higher 25(OH)D concentration was strongly correlated with lower HOMA-IR and insulin values independent of VFA (p < 0.01) but significantly affected by CRF. In the high CRF group, participants with higher 25(OH)D concentration had lower HOMA-IR values than participants with low 25(OH)D concentration (p < 0.05). Higher 25(OH)D and CRF are crucial for reducing insulin resistance regardless of abdominal fat. In addition, higher 25(OH)D concentration may strengthen the effect of CRF on reducing insulin resistance in middle-aged and elderly Japanese men with high CRF.