Relevance of hepatic lipase to the metabolism of triacylglycerol-rich lipoproteins

2003 ◽  
Vol 31 (5) ◽  
pp. 1070-1074 ◽  
Author(s):  
A. Zambon ◽  
S. Bertocco ◽  
N. Vitturi ◽  
V. Polentarutti ◽  
D. Vianello ◽  
...  
Keyword(s):  
Arterial Wall ◽  
Disease Risk ◽  
Lipolytic Activity ◽  
Hepatic Lipase ◽  
Heparan Sulphate ◽  
Genetic Regulation ◽  
Density Lipoprotein ◽  
Hepatic Uptake ◽  
Small Dense Ldl ◽  
Ldl Particles

HL (hepatic lipase) is a glycoprotein that is synthesized and secreted by the liver, and which binds to heparan sulphate proteoglycans on the surface of sinusoidal endothelial cells and on the external surface of parenchymal cells in the space of Disse. HL catalyses the hydrolysis of triacylglycerols and phospholipids in different lipoproteins, contributing to the remodelling of VLDL (very-low-density lipoprotein) remnants, as well as IDL, LDL and HDL (intermediate-, low- and high-density lipoprotein respectively). HL deficiency in humans is associated with diminished conversion of VLDL remnants into IDL and a near-complete absence of IDL-to-LDL conversion. Remnant lipoproteins and IDL are major determinants of coronary artery disease risk, and accumulation of these lipoproteins in the presence of low HL activity might lead to increased atherosclerosis. In addition to and independently of its lipolytic activity, HL participates as a ligand in promoting the hepatic uptake of remnants and IDL particles, and the latter may represent an additional mechanism linking low HL levels to plasma accumulation of these atherogenic lipoproteins. On the other hand, high HL activity may also result in an increased atherosclerotic risk by promoting the formation of atherogenic small, dense LDL particles. Finally, HL is also synthesized by human macrophages, suggesting that, at the arterial wall site, HL may also contribute locally to promote atherosclerosis by enhancing the formation and retention in the subendothelial space of the arterial wall of VLDL remnants, IDL and small, dense LDL. In conclusion, by interfering with the metabolism of apolipoprotein B100-containing lipoproteins, HL may have pro- as well as anti-atherogenic effects. The anti- or pro-atherogenic role of HL is likely to be modulated by the concurrent presence of other lipid abnormalities (i.e. LDL-cholesterol levels), as well as by the genetic regulation of other enzymes involved in lipoprotein metabolism.

scholarly journals Oxidative Modification of Lipoproteins: A Potential Role of Oxidized Small dense LDL in Enhanced Atherogenicity

2021 ◽  
pp. 118-140
Author(s):  
Mohammed Alsaweed
Keyword(s):  
Arterial Wall ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Predictive Marker ◽  
Oxidative Modification ◽  
Cholesterol Homeostasis ◽  
Low Density ◽  
Small Dense Ldl ◽  
Ldl Particles ◽  
Apoprotein B

Atherosclerosis (AS) is a multifaceted inflammatory syndrome of the arterial wall to which number of mediators have been implicated in lesion progression. Triglyceride (TG)-rich lipoproteins consist of the large diversity of lipoprotein particles that fluctuate in density, size, and apolipoprotein composition. Two foremost phenotypes, on basis of size, chemical configuration, and density, of low-density-lipoprotein (LDL) have been recognized i.e., pattern A, having LDL diameter greater than 25.5nm (large buoyant LDL or lb-LDL) and pattern B, having LDL diameter less than or equal to 25.5nm (small-dense LDL or sd-LDL). Small-dense low-density-lipoprotein (sd-LDL) particles are produced by potential intravascular hydrolysis of TG-rich VLDL particles via lipoprotein lipases (LPLs), hepatic lipases (HLs) and cholesterol ester transfer protein (CETP). sd-LDL is more atherogenic due to its smaller size, increased penetration into the arterial wall, extended plasma half-life, lesser binding affinity for LDL receptors (LDL-R) as well as lower resistance to oxidative stress when equated with lb-LDL. The higher atherogenic potential of sd-LDL is due to its enhanced susceptibility to oxidation, owing to high polyunsaturated fatty acids (PUFA), low cholesterol and Apoprotein B (ApoB) content. An enhanced understanding of sd-LDL metabolism at the molecular level, transport and clearance may result in the development of sd-LDL as an independent predictive marker for AS events and may be used to maintain cholesterol homeostasis and prevent the succession of AS.

Triacylglycerol-rich lipoproteins and the generation of small, dense low-density lipoprotein

2003 ◽  
Vol 31 (5) ◽  
pp. 1066-1069 ◽  
Author(s):  
C.J. Packard
Keyword(s):  
Residence Time ◽  
Hepatic Lipase ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Predisposing Factor ◽  
Small Dense Ldl ◽  
Lipoprotein Class ◽  
Ldl Particles ◽  
Clinical Benefits

LDL (low-density lipoprotein) is the major carrier of cholesterol in human plasma, and as such is intimately involved in the process of atherosclerosis. The lipoprotein class comprises a number of distinct subfractions, and is commonly divided into large, intermediate and small sized particles. Small, dense LDLs are held to be particularly atherogenic, since these particles are retained preferentially by the artery wall, are readily oxidized and carry an enzyme believed to have an important role in atherosclerosis, i.e. lipoprotein-associated phospholipase A2. Generation of small, dense LDL occurs by intravascular lipoprotein remodelling as a result of disturbances such as Type II diabetes, metabolic syndrome, renal disease and pre-eclampsia. The key predisposing factor is the development of hypertriglyceridaemia, in particular elevation in the plasma concentration of large, triacylglycerol-rich VLDL (very-low-density lipoprotein). This leads to the formation of slowly metabolized LDL particles (5-day residence time), which are subject to exchange processes that remove cholesteryl ester from the particle core and replace it with triacylglycerol. LDL, so altered, is a potential substrate for hepatic lipase; if the activity of the enzyme is high enough, lipolysis will generate smaller, denser particles. Correction of the dyslipidaemia associated with small, dense LDL is possible using fibrates and statins, and this may contribute to the clinical benefits seen with these drugs. Fibrates act to lower plasma triacylglycerol (VLDL) levels, and so correct the underlying metabolic disturbance. Statins remove VLDL particles via receptor-mediated pathways and reduce the residence time (and hence limit the potential for remodelling) of LDL in the circulation.

scholarly journals Pemafibrate decreases triglycerides and small, dense LDL, but increases LDL-C depending on baseline triglycerides and LDL-C in type 2 diabetes patients with hypertriglyceridemia: an observational study

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Ichiro Komiya ◽  
Akira Yamamoto ◽  
Suguru Sunakawa ◽  
Tamio Wakugami
Keyword(s):  
Type 2 Diabetes ◽  
Disease Risk ◽  
Direct Method ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Small Dense Ldl ◽  
Group I ◽  
Diabetes Patients

Abstract Background Pemafibrate, a selective PPARα modulator, has the beneficial effects on serum triglycerides (TGs) and very low density lipoprotein (VLDL), especially in patients with diabetes mellitus or metabolic syndrome. However, its effect on the low density lipoprotein cholesterol (LDL-C) levels is still undefined. LDL-C increased in some cases together with a decrease in TGs, and the profile of lipids, especially LDL-C, during pemafibrate administration was evaluated. Methods Pemafibrate was administered to type 2 diabetes patients with hypertriglyceridemia. Fifty-one type 2 diabetes patients (mean age 62 ± 13 years) with a high rate of hypertension and no renal insufficiency were analyzed. Pemafibrate 0.2 mg (0.1 mg twice daily) was administered, and serum lipids were monitored every 4–8 weeks from 8 weeks before administration to 24 weeks after administration. LDL-C was measured by the direct method. Lipoprotein fractions were measured by electrophoresis (polyacrylamide gel, PAG), and LDL-migration index (LDL-MI) was calculated to estimate small, dense LDL. Results Pemafibrate reduced serum TGs, midband and VLDL fractions by PAG. Pemafibrate increased LDL-C levels from baseline by 5.3% (− 3.8–19.1, IQR). Patients were divided into 2 groups: LDL-C increase of > 5.3% (group I, n = 25) and < 5.3% (group NI, n = 26) after pemafibrate. Compared to group NI, group I had lower LDL-C (2.53 [1.96–3.26] vs. 3.36 [3.05–3.72] mmol/L, P = 0.0009), higher TGs (3.71 [2.62–6.69] vs. 3.25 [2.64–3.80] mmol/L), lower LDL by PAG (34.2 [14.5, SD] vs. 46.4% [6.5], P = 0.0011), higher VLDL by PAG (28.2 [10.8] vs. 22.0% [5.2], P = 0.0234), and higher LDL-MI (0.421 [0.391–0.450] vs. 0.354 [0.341–0.396], P < 0.0001) at baseline. Pemafibrate decreased LDL-MI in group I, and the differences between the groups disappeared. These results showed contradictory effects of pemafibrate on LDL-C levels, and these effects were dependent on the baseline levels of LDL-C and TGs. Conclusions Pemafibrate significantly reduced TGs, VLDL, midband, and small, dense LDL, but increased LDL-C in diabetes patients with higher baseline TGs and lower baseline LDL-C. Even if pre-dose LDL-C remains in the normal range, pemafibrate improves LDL composition and may reduce cardiovascular disease risk.

New Insights into Cardiovascular Disease Risk in Subjects with Visceral Obesity

2003 ◽  
Vol 15 (1_suppl) ◽  
pp. S37-S40 ◽  
Author(s):  
AP James ◽  
K Slivkoff-Clark ◽  
JCL Mamo
Keyword(s):  
Disease Risk ◽  
Cardiovascular Disease Risk ◽  
Low Density Lipoprotein ◽  
Visceral Obesity ◽  
Density Lipoprotein ◽  
Hdl Cholesterol ◽  
Insulin Resistant ◽  
Essentially Normal ◽  
Ldl Particles ◽  
Chylomicron Metabolism

Obese insulin resistant individuals often present with a dyslipidemic phenotype characterised by hypertriglyceridemia, low HDL cholesterol levels, essentially normal total- and LDL-cholesterol, but a propensity for smaller, denser LDL particles. We have reported that concentrations of chylomicrons are two to three folds greater than in age-matched lean controls. We have recently observed that in lean free-living subjects the flux of chylomicrons over a 12h period was just 25% greater in these subjects than basal chylomicron production. Constitutive secretion of chylomicrons appears to be of greater relevance to arterial exposure than postprandial fluctuations. Insulin critically regulates the metabolism of very low density lipoprotein (VLDL) and hence it would be expected that the hormone is also involved in the regulation of chylomicron metabolism. Impaired insulin action may therefore be responsible for the associated hyperchylomicronaemia. In this review we examine the hypothesis that insulin chronically modulates chylomicron metabolism and present evidence suggesting that hyperchylomicronaemia primarily results from impaired chylomicron production.

Triglyceride-Rich Lipoproteins as a Source of Proinflammatory Lipids in the Arterial Wall

2019 ◽  
Vol 26 (9) ◽  
pp. 1701-1710 ◽  
Author(s):  
Katariina Öörni ◽  
Satu Lehti ◽  
Peter Sjövall ◽  
Petri T. Kovanen
Keyword(s):  
Arterial Wall ◽  
Disease Risk ◽  
Cardiovascular Disease Risk ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density Lipoproteins ◽  
Low Density ◽  
Lipoprotein Particles ◽  
Atherosclerotic Lesions ◽  
Remnant Lipoproteins

Apolipoprotein B –containing lipoproteins include triglyceride-rich lipoproteins (chylomicrons and their remnants, and very low-density lipoproteins and their remnants) and cholesterol-rich low-density lipoprotein particles. Of these, lipoproteins having sizes below 70-80 nm may enter the arterial wall, where they accumulate and induce the formation of atherosclerotic lesions. The processes that lead to accumulation of lipoprotein-derived lipids in the arterial wall have been largely studied with a focus on the low-density lipoprotein particles. However, recent observational and genetic studies have discovered that the triglyceriderich lipoproteins and their remnants are linked with cardiovascular disease risk. In this review, we describe the potential mechanisms by which the triglyceride-rich remnant lipoproteins can contribute to the development of atherosclerotic lesions, and highlight the differences in the atherogenicity between low-density lipoproteins and the remnant lipoproteins.

scholarly journals The Contribution of Intraabdominal Fat to Gender Differences in Hepatic Lipase Activity and Low/High Density Lipoprotein Heterogeneity1

2001 ◽  
Vol 86 (6) ◽  
pp. 2831-2837 ◽  
Author(s):  
Molly C. Carr ◽  
John E. Hokanson ◽  
Alberto Zambon ◽  
Samir S. Deeb ◽  
P. Hugh R. Barrett ◽  
...  
Keyword(s):  
Gender Difference ◽  
High Density Lipoprotein ◽  
Hepatic Lipase ◽  
Density Lipoprotein ◽  
Premenopausal Women ◽  
Promoter Polymorphism ◽  
Male Gender ◽  
High Density ◽  
Ldl Particles ◽  
The Difference

Hepatic lipase (HL) hydrolyzes triglyceride and phospholipid in low and high density lipoprotein cholesterol (LDL-C and HDL-C, respectively), and elevated HL activity is associated with small, dense atherogenic LDL particles and reduced HDL2-C. Elevated HL activity is associated with increasing age, male gender, high amounts of intraabdominal fat (IAF), and the HL gene (LIPC) promoter polymorphism (C nucleotide at −514). We investigated the mechanisms underlying the difference in HL activity between men (n = 44) and premenopausal women (n = 63). Men had significantly more IAF (144.5 ± 80.9 vs. 66.5 ± 43.2 cm2, respectively; P&lt; 0.001), higher HL activity (220.9 ± 94.7 vs.129.9 ± 53.5 nmol/mL·min; P &lt; 0.001), more dense LDL (Rf, 0.277 ± 0.032 vs. 0.300 ± 0.024; P = 0.01), and less HDL2-C (0.19 ± 0.10 vs. 0.32± 0.16 mmol/L; P &lt; 0.001) than women. After adjusting for IAF and the LIPC polymorphism, men continued to have higher (but attenuated) HL activity (194.5 ± 80.4 vs.151.0 ± 45.2, respectively; P = 0.007) and lower HDL2-C (0.23 ± 0.11 vs. 0.29 ± 0.14 mmol/L; P = 0.02) than women. Using multiple regression, HL activity remained independently related to IAF (P &lt; 0.001), gender (P &lt; 0.001), and the LIPC genotype (P &lt; 0.001), with these factors accounting for 50% of the variance in HL activity. These data suggest that IAF is a major component of the gender difference in HL activity, but other gender-related differences, perhaps sex steroid hormones, also contribute to the higher HL activity seen in men compared with premenopausal women. The higher HL activity in men affects both LDL and HDL heterogeneity and may contribute to the gender difference in cardiovascular risk.

Abstract 538: LDL Particle Core Enrichment in Cholesteryl Oleate Results in Increased Binding to Arterial Wall Proteoglycans and Increased Atherosclerosis

2012 ◽  
Vol 32 (suppl_1) ◽  
Author(s):  
John Melchior ◽  
Kathryn Kelley ◽  
Martha Wilson ◽  
Janet Sawyer ◽  
Roy Hantgan ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Arterial Wall ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Surface Characteristics ◽  
Cholesterol Content ◽  
Cholesteryl Oleate ◽  
Size Exclusion ◽  
Apo B ◽  
Ldl Particles

INTRODUCTION: Accumulation of lipids in the artery wall, particularly cholesteryl esters (CE), is a classic feature of atherosclerosis. Apo B-containing lipoprotein particles are the primary vehicles by which CEs are delivered across the endothelial barrier into the intima and once present in the subendothelial space these particles are subject to sequestration by native proteoglycans. Several studies in both non-human primate and murine models of atherosclerosis strongly suggest that core enrichment in cholesteryl oleate of low-density lipoprotein (LDL) particles play a significant role in determination of the extent of atherosclerosis. It has also been shown that Acyl-CoA:cholesterol O-acyltransferase 2 (ACAT2) is the enzyme responsible for cholesteryl oleate enrichment of apo B-containing lipoproteins and gene deletion of ACAT2 in animal models is protective against the development of atherosclerosis. Thus, we hypothesized that the selective accumulation of LDL within the intima is the result of LDL particle core enrichment of cholesteryl oleate that results in modification of key surface characteristics of ApoB promoting interaction with resident proteoglycans. METHODS: Apo B-100 only, LDLr -/- mice (W/T) and Apo B-100 only, LDLr-/-, ACAT2 -/- (KO) mice were fed diets enriched in either cis-monounsaturated fatty acids (cis-MUFA) or n-3 polyunsaturated fatty acids (n-3 PUFA) for 16 weeks. Blood and plasma was harvested and LDL particles were isolated by size exclusion chromatography. The major lipid constituents of the LDL particle were measured along with the fatty acids of the cholesteryl ester fraction of the particle core. LDL affinity to arterial proteoglycans was determined using an immunocapture surface plasmon resonance (SPR) technique we developed. Atherosclerosis was quantified by measuring the cholesterol content of the aorta. RESULTS: W/T mice fed a cis-MUFA diet displayed the highest degree of cholesteryl oleate packaging into the particle core and the highest propensity to bind to arterial proteoglycans. Feeding a diet enriched in n-3 PUFA and/or knocking out ACAT2 successfully inhibited the packaging of cholesteryl oleate into the LDL particles. Accompanying this decrease in cholesteryl oleate content was a significant decrease in binding to arterial proteoglycans and development of atherosclerosis. CONCLUSION: Elimination of cholesteryl oleate from the LDL particle core results in significantly less binding to arterial wall proteoglycans and in turn, less development of atherosclerosis.

scholarly journals Lipoprotein atherogenicity: an overview of current mechanisms

1999 ◽  
Vol 58 (1) ◽  
pp. 163-169 ◽  
Author(s):  
Bruce A. Griffin
Keyword(s):  
Particle Size ◽  
Serum Cholesterol ◽  
Arterial Wall ◽  
Cholesterol Content ◽  
Oxidative Modification ◽  
Cross Sectional ◽  
Small Dense Ldl ◽  
Ldl Particles ◽  
Increased Risk ◽  
Tissue Matrix

Raised serum cholesterol does not adequately explain the increased risk of CHD within populations or the relationship between diet and CHD. Nevertheless, the principal transport vehicle of cholesterol in the circulation, LDL, must still be regarded as the most atherogenic lipoprotein species, but not because of its contribution to serum cholesterol. The atherogenic potential of LDL in the majority of individuals arises from an increase in the number of small dense LDL particles and not from its cholesterol content per se. There is now a wealth of evidence from cross-sectional and prospective studies to show that LDL particle size is significantly associated with CHD and predictive of increased coronary risk. Moreover, there are a number of credible mechanisms to link small dense LDL with the atherogenic process. The rate of influx of serum lipoproteins into the arterial wall is a function of particle size, and will thus be more rapid for small dense LDL. Components of the extracellular tissue matrix in the intima, most notably proteoglycans, selectively bind small dense LDL with high affinity, sequestering this lipoprotein in a pro-oxidative environment. The oxidation of LDL promotes the final deposition of cholesterol in the arterial wall, and numerous studies have shown small dense LDL to be more susceptible to oxidative modification than its larger and lighter counterparts. An increase in the number of small dense LDL particles may originate from a defect in the metabolism of triacylglycerol-rich lipoproteins. One mechanism may involve the overproduction and increased residence time of large triacylglycerol-rich VLDL in the postprandial phase, a situation thought to arise through pathways of insulin resistance.

scholarly journals The effects of fat consumption on low-density lipoprotein particle size in healthy individuals: a narrative review

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Erik Froyen
Keyword(s):  
Fatty Acids ◽  
Particle Size ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Healthy Individuals ◽  
Cvd Risk ◽  
Small Dense Ldl ◽  
Ldl Particles ◽  
Fat Consumption

AbstractCardiovascular disease (CVD) is the number one contributor to death in the United States and worldwide. A risk factor for CVD is high serum low-density lipoprotein cholesterol (LDL-C) concentrations; however, LDL particles exist in a variety of sizes that may differentially affect the progression of CVD. The small, dense LDL particles, compared to the large, buoyant LDL subclass, are considered to be more atherogenic. It has been suggested that replacing saturated fatty acids with monounsaturated and polyunsaturated fatty acids decreases the risk for CVD. However, certain studies are not in agreement with this recommendation, as saturated fatty acid intake did not increase the risk for CVD, cardiovascular events, and/or mortality. Furthermore, consumption of saturated fat has been demonstrated to increase large, buoyant LDL particles, which may explain, in part, for the differing outcomes regarding fat consumption on CVD risk. Therefore, the objective was to review intervention trials that explored the effects of fat consumption on LDL particle size in healthy individuals. PubMed and Web of Science were utilized during the search process for journal articles. The results of this review provided evidence that fat consumption increases large, buoyant LDL and/or decreases small, dense LDL particles, and therefore, influences CVD risk.

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