Buoyant Low-density Lipoprotein Particles Research Articles

VLDL and LDL Subfractions Enhance the Risk Stratification of Individuals Who Underwent Epstein-Barr Virus-Based Screening for Nasopharyngeal Carcinoma: A Multicenter Cohort Study.

Serological tests for Epstein-Barr virus (EBV) antibodies have been widely conducted for the screening of nasopharyngeal carcinoma (NPC) in endemic areas. Further risk stratification of NPC can be achieved through plasma lipoprotein and metabolic profiles. A total of 297 NPC patients and 149 EBV-positive participants are enrolled from the NCT03919552 and NCT05682703 cohorts for plasma nuclear magnetic resonance (NMR) metabolomic analysis. Small, dense very low density lipoprotein particles (VLDL-5) and large, buoyant low density lipoprotein particles (LDL-1) are found to be closely associated with nasopharyngeal carcinogenesis. Herein, an NMR-based risk score (NRS), which combines lipoprotein subfractions and metabolic biomarkers relevant to NPC, is developed and well validated within a multicenter cohort. Combining the median cutoff value of the NRS (N50) with that of the serological test for EBV antibodies, the risk stratification model achieves a satisfactory performance in which the area under the curve (AUC) is 0.841 (95% confidence interval: 0.811-0.871), and the positive predictive value (PPV) reaches 70.08% in the combined cohort. These findings not only suggest that VLDL-5 and LDL-1 particles can serve as novel risk factors for NPC but also indicate that the NRS has significant potential in personalized risk prediction for NPC.

Lipid Profile Changes Associated with SGLT-2 Inhibitors and GLP-1 Agonists in Diabetes and Metabolic Syndrome.

The introduction of sodium glucose transporter-2 inhibitors and glucagon-like peptide-1 receptor agonists in type 2 diabetes mellitus treatment has shown an unexpectedly significant improvement in heart disease outcome trials. Although they have very different modes of action, a portion of the salutary cardiovascular disease improvement may be related to their impact on diabetic dyslipidemia. As discussed in this focused review, the sodium glucose transporter-2 inhibitors as a class show a mild increase in low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol levels, while triglycerides (TG) decrease inconsistently. In particular, the rise in LDL appears to be related to the less atherogenic, large buoyant LDL particles. The glucagon-like peptide-1 receptor agonists show more of an impact on weight loss and improvement in the underlying low HDL and high TG dyslipidemia. The effect of sodium glucose transporter-2 inhibitors and glucagon-like peptide 1 receptor agonists when used in combination remains largely unknown. Also unexplored is difference in effect of these medications among various ethnicities and metabolic syndrome.

Metabolic alterations, HFE gene mutations and atherogenic lipoprotein modifications in patients with primary iron overload.

Iron overload (IO) has been associated with glucose metabolism alterations and increased risk of cardiovascular disease (CVD). Primary IO is associated with mutations in the HFE gene. To which extent HFE gene mutations and metabolic alterations contribute to the presence of atherogenic lipoprotein modifications in primary IO remains undetermined. The present study aimed to assess small, dense low-density lipoprotein (LDL) levels, chemical composition of LDL and high-density lipoprotein (HDL) particles, and HDL functionality in IO patients. Eighteen male patients with primary IO and 16 sex- and age-matched controls were recruited. HFE mutations (C282Y, H63D and S65C), measures of insulin sensitivity and secretion (calculated from the oral glucose tolerance test), chemical composition and distribution profile of LDL and HDL subfractions (isolated by gradient density ultracentrifugation) and HDL functionality (as cholesterol efflux and antioxidative activity) were studied. IO patients compared with controls exhibited insulin resistance (HOMA-IR (homoeostasis model assessment-estimated insulin resistance): +93%, P< 0.001). Metabolic profiles differed across HFE genotypes. C282Y homozygotes (n=7) presented a reduced β-cell function and insulin secretion compared with non-C282Y patients (n=11) (-58% and -73%, respectively, P< 0.05). In addition, C282Y homozygotes featured a predominance of large, buoyant LDL particles (C282Y: 43±5; non-C282Y: 25±8; controls: 32±7%; P< 0.001), whereas non-C282Y patients presented higher amounts of small, dense LDL (C282Y: 23±5; non-C282Y: 39±10; controls: 26±4%; P< 0.01). HDL particles were altered in C282Y homozygotes. However, HDL functionality was conserved. In conclusion, metabolic alterations and HFE gene mutations are involved in the presence of atherogenic lipoprotein modifications in primary IO. To what extent such alterations could account for an increase in CVD risk remains to be determined.

Enriched n-3 polyunsaturated fatty acids of dense LDL subfraction in Japanese women with small, dense LDL categorized by non-denaturing gradient gel electrophoresis

Small, dense low density lipoprotein (LDL) has been suggested to be highly atherogenic as a result of their low-binding affinity to LDL receptors, their prolonged plasma half-life and low resistance to oxidative stress. Although marine n-3 polyunsaturated fatty acids (PUFAs) have beneficial effects for the prevention of cardiovascular diseases, there is little information on detailed fatty acid composition in LDL particles. In the present study, LDL subfractions were isolated from the plasma of 45 clinically healthy Japanese women by density gradient ultracentrifugation using a light fraction of 1.025-1.034 g/ml (LDL-I), an intermediate fraction of 1.034-1.044 g/ml (LDL-II), and a dense fraction of 1.044-1.060 g/ml (LDL-III). A clear relationship between the frequency of fish intake and increases in plasma n-3 PUFAs was apparent. Although plasma n-3 PUFAs in women with small-sized LDL using non-denaturing gradient gel electrophoresis (GGE) did not show a significant difference, n-3 PUFAs and n-3 PUFAs/n-6 PUFAs in dense LDL-III subfraction increased in the small-sized LDL group using GGE, compared to those with buoyant LDL particles. The result of enriched n-3 PUFAs in dense LDL subfraction suggests that n-3 PUFAs may help prevent atherosclerosis in the arteries of Japanese women with small-sized LDL.

Nicotinic acid in the management of dyslipidaemia associated with diabetes and metabolic syndrome: a position paper developed by a European Consensus Panel

ABSTRACTIndividuals with type 2 diabetes and metabolic syndrome are at markedly increased risk of cardiovascular morbidity and mortality. The increasing prevalence of both conditions poses a major challenge for clinicians in the 21st century. Both diabetes and metabolic syndrome are associated with a clustering of cardiovascular risk factors. In particular, dyslipidaemia characterised by low plasma levels of high-density lipoprotein cholesterol (HDL‐C), elevated triglycerides and an increase in small, dense low‐density lipoprotein (LDL) particles (the lipid triad), has been established as the most important modifiable risk factor for coronary heart disease (CHD).Current treatment guidelines recognise the increased CHD risk associated with diabetes and metabolic syndrome and focus on LDL-C lowering with statin treatment, in addition to dietary and lifestyle modification, as the primary lipid-modifying therapy. However, while there is no doubt that statin therapy significantly reduces CHD risk in these patients, their residual absolute risk remains higher than in individuals without diabetes or metabolic syndrome. Thus, there is a clear need to target other aspects of lipoprotein metabolism, notably low HDL-C and hypertriglyceridaemia, to further reduce CHD risk. Combining statin therapy (targeting LDL-C) with interventions that also modify low HDL-C and elevated triglycerides could be a useful strategy to optimise CHD risk reduction. Cautious combination of a fibrate or nicotinic acid with a statin is useful for the management of combined dyslipidaemia. Nicotinic acid is the more potent agent for raising HDL-C (by up to 29% at clinically recommended doses). It also substantially reduces triglycerides and LDL-C, and promotes a shift from small, dense LDL to larger, more buoyant LDL particles. Preliminary clinical data suggest that combining nicotinic acid with a statin will produce a greater reduction in cardiovascular risk in patients with diabetes and metabolic syndrome than statin monotherapy alone. Nicotinic acid is also safe for use in patients with diabetes, with no evidence of clinically relevant deterioration in glycaemic control at recommended doses (≤ 2 g/day). On review of the available evidence, this European Consensus Panel recommends the combination of nicotinic acid and a statin, together with lifestyle modification, as a useful strategy to lower CHD risk in patients with diabetes and metabolic syndrome. Prolonged-release nicotinic acid with improved tolerability compared with previous formulations may have obvious advantages for use in this setting.

The small, dense LDL phenotype as a correlate of postprandial lipemia in men

The atherogenic dyslipidemia of the insulin resistance syndrome is characterized by hypertriglyceridemia (hyperTG), elevated apolipoprotein (apo) B levels, reduced high-density lipoprotein (HDL) cholesterol concentrations and by an increased proportion of small, dense low-density lipoprotein (LDL) particles. Although the hyperTG-low HDL cholesterol dyslipidemia has been associated with an impaired clearance of dietary fat, the contribution of the small, dense LDL phenotype as an independent predictor of postprandial triglyceride (TG) clearance remains uncertain. We have therefore compared the postprandial TG response among three subgroups of men characterized by small, intermediate or large LDL particles in a total sample of 69 men (mean age±SD; 45.1±10.5 years). To identify men with small versus large LDL particles, the first (LDL peak particle diameter<251.9 Å) and the third (>257.6 Å) tertiles of the distribution of LDL particle diameters were used as cutoff points. Men with small, dense LDL particles had the expected fasting dyslipidemic profile (high TG-low HDL cholesterol levels) compared to men with large, buoyant LDL particles. The oral lipid tolerance test revealed that men with small, dense LDL particles had significantly higher total-, large-, and medium-TG-rich lipoprotein (TRL) responses to a fatty meal than men with large LDL particles ( P<0.03). In addition, within a subgroup of normolipidemic men (TG<2.3 mmol/l and HDL cholesterol>0.9 mmol/l), those with small, dense LDL particles had higher levels of total-, medium- and small-TRL responses compared to men with large, buoyant LDL particles ( P<0.05). Moreover, normotriglyceridemic men with small, dense LDL had higher levels of small-TRLs measured 8 h after the ingestion of the fat meal ( P<0.05) compared to normolipidemic men with large, buoyant LDL particles. Results of the present study suggest that the dense LDL phenotype may be an additional fasting marker of an exaggerated postprandial TG response and of an impaired clearance of TRLs.

Pancreas transplantation modulates reverse cholesterol transport.

Hyperinsulinemia secondary to insulin resistance in type-II diabetes or in the metabolic syndrome is associated with the "atherogenetic lipoprotein phenotype": high triglycerides, small, dense low-density lipoprotein (LDL) cholesterol, and low high-density lipoprotein (HDL) cholesterol. In contrast, hyperinsulinemia in pancreas-kidney transplant recipients (PKT-R), secondary to systemic venous drainage of the heteropically implanted pancreas graft, leads to high lipoprotein lipase (LPL) activity and a presumably antiatherogenic lipoprotein profile with very attenuated postprandial lipemia, high HDL cholesterol, and a preponderance of large-sized HDL (HDL(2)) and large buoyant LDL particles. We interpret these findings to suggest that in PKT-R, peripheral hyperinsulinemia upregulates LPL activity in peripheral tissues, which induces rapid clearance of chylomicron triglycerides from plasma and, thus, attenuates postprandial lipemia. Low postprandial lipemia allows little net cholesteryl ester transfer from HDL to triglyceride-rich lipoproteins, keeping the levels of the antiatherogenic lipoprotein HDL high and potentially increasing, thereby reverse cholesterol transport. The type of lipoprotein metabolism and pattern present in PKT-R is associated with a low cardiovascular risk in the general population; it cannot be excluded, however, that hyperinsulinemia as found in PKT-R may contribute to atherosclerosis by effects unrelated to lipoprotein metabolism.

LDL particle size: an important drug target?

Low density lipoprotein (LDL) is the main carrier of plasma cholesterol and a major component of atherosclerotic plaque [1]. Lowering LDL cholesterol reduces coronary events and mortality from coronary artery disease (CAD) [2–4], however, the relation between LDL cholesterol concentration and (CAD) is complex. Many patients with CAD have plasma LDL cholesterol concentrations in the normal rangefor the general population [5]. Thus, it could be that coronary risk goes beyond LDL cholesterol concentration to the characteristics of the LDL particles themselves. The purpose of this communication is to address the issue of whether LDL particle size and density influences its atherogenecity and how this might be modified by drug therapy.

Influence of mild to moderately elevated triglyceride’s on low density lipoprotein subfraction concentration and composition in healthy men with low high density lipoprotein cholesterol levels

Epidemiologic studies have shown that a dyslipoproteinemia with low concentrations of high density lipoprotein (HDL) cholesterol and elevated serum triglycerides (TG) is associated with a particularly high incidence of coronary artery disease. This lipid profile is associated with increased concentrations of small, dense low density lipoprotein (LDL) particles. To evaluate the role of mild to moderately elevated TG on the LDL subfraction profile in patients with low HDL cholesterol, concentration and composition of six LDL subfractions was determined by density gradient ultracentrifugation in 41 healthy men (31±9 years, body mass index (BMI) 25.1±3.9 kg/m 2) with equally low HDL cholesterol levels <0.91 mmol/l but different TG levels: TG<1.13 mmol/l, n=16; TG=1.13–2.26 mmol/l, n=13; TG=2.26–3.39 mmol/l, n=12. Those men with moderately elevated TG levels between 2.26 and 3.39 mmol/l had significantly higher concentrations of very low density lipoprotein (VLDL), intermediate low density lipoprotein (IDL), and small, dense LDL apoB and cholesterol than men with TG <1.13 mmol/l. With increasing serum TG, the TG content per particle also increased in VLDL, IDL as well as total LDL particles while the cholesterol and phospholipid (PL) content decreased in VLDL and IDL, but not in LDL particles. LDL subfraction analysis revealed that only large, more buoyant LDL particles ( d<1.044 g/ml) but not the smaller, more dense LDL, were enriched in TG. Small, dense LDL particles were depleted of free cholesterol (FC) and PL. This study has shown that in men with low HDL cholesterol levels mild to moderately elevated serum TG strongly suggest the presence of other metabolic cardiovascular risk factors and in particular of a more atherogenic LDL subfraction profile of increased concentration of small, dense LDL particles that are depleted in surface lipids.

Lipid and lipoprotein profile of Japanese centenarians--high prevalence of hypo beta lipoproteinemia

To study the relationship between lipids and longevity, we examined the level of serum lipids and apolipoproteins, and the susceptibility of low density lipoprotein (LDL) to oxidation of 45 centenarians (15 men, 30 women, mean age 101.1 +/- 1.4) living in the Tokyo metropolitan area. The average levels of total cholesterol (TC), of LDL-C of high-density lipoprotein cholesterol (HDL-C), and of apolipoproteins A1 and B were significantly lower in centenarians than in healthy middle-aged controls. The frequency of hypobeta-lipoproteinemia (apoB < 60 mg/dl) in centenarians was almost ten times as high as in controls. The time course of copper-mediated LDL, oxidation (assessed by monitoring 234 nm diene absorption (lag time)) did not significantly differ between the two groups. Analysis of LDL subfractions by non-denaturated gradient-gel electrophoresis showed a predominance of large, buoyant LDL particles (pattern A) in 75%, and a predominance of small dense LDL particles (pattern B) in 25% of centenarians. We also assessed activities of daily living (ADL) and cognitive function in the centenarians. Centenarians were divided into two groups according to the median ADL score, and were classified into five groups with a scale clinical dementia. In subjects with good ADL scores, the mean concentration of HDL-3-C was significantly higher than in those with poor ADL scores. Average levels of HDL-C were also significantly lower in subjects with moderate or severe dementia than in those with normal cognitive function. These findings suggest that centenarians have protective phenotypes of lipids and lipoproteins that protect them from atheroscierosis.

Susceptibility of small, dense, low-density lipoproteins to oxidative modification in subjects with the atherogenic lipoprotein phenotype, pattern B

purpose: To test whether low-density lipoprotein (LDL) from subjects with an atherogenic lipoprotein phenotype characterized by small, dense LDL (pattern B) demonstrates greater susceptibility to oxidative modification than LDL from subjects exhibiting primarily larger, more buoyant LDL particles (pattern A). patients and methods: Measures of susceptibility to oxidative modification were compared in six density subfractions of LDL isolated from pattern A and pattern B subjects. Seven male and three female pattern A subjects and five male and two female pattern B subjects, classified on the basis of peak LDL particle size, were studied. Plasma lipid and lipoprotein levels, apolipoprotein B, mean LDL particle diameter, lag phase, and rate of oxidation after initiation of oxidation by copper sulfate were measured. results: The lag time, a measure of resistance to oxidative modification, was inversely related (p < 0.001) to LDL density in both groups of subjects, without an independent effect of phenotype. The fraction that had the major LDL peak had a shorter lag time (p < 0.05) in pattern B than in pattern A. Pattern B subjects also demonstrated an increased rate of oxidation (p < 0.005) in fraction 1, which includes remnants of triglyceride-rich lipoproteins. conclusions: The increased atherogenic risk associated with the pattern B phenotype may result in part from increased concentrations of lipoprotein subpopulations that are relatively susceptible to oxidative modification.

Atherogenic lipoprotein phenotype. A proposed genetic marker for coronary heart disease risk.

In a community-based study of 301 subjects from 61 nuclear families, two distinct phenotypes (denoted A and B) were identified by nondenaturing gradient gel electrophoretic analysis of low density lipoprotein (LDL) subclasses. Phenotype A was characterized by predominance of large, buoyant LDL particles, and phenotype B consisted of a major peak of small, dense LDL particles. Previous analysis of the family data by complex segregation analysis demonstrated that these phenotypes appear to be inherited as a single-gene trait. In the present study, the phenotypes were found to be closely associated with variations in plasma levels of other lipid, lipoprotein, and apolipoprotein measurements. Specifically, phenotype B was associated with increases in plasma levels of triglyceride and apolipoprotein B, with mass of very low and intermediate density lipoproteins, and with decreases in high density lipoprotein (HDL) cholesterol, HDL2 mass, and plasma levels of apolipoprotein A-I. Thus, the proposed genetic locus responsible for LDL subclass phenotypes also results in an atherogenic lipoprotein phenotype.

Inheritance of low density lipoprotein subclass patterns in familial combined hyperlipidemia.

The inheritance of low density lipoprotein (LDL) subclass patterns was investigated in 234 members of seven large kindreds with familial combined hyperlipidemia (FCHL), a disorder characterized by elevated LDL cholesterol and/or triglyceride and increased coronary disease risk in families. Analysis of LDL subclasses by nondenaturing gradient gel electrophoresis showed a predominance of large, buoyant LDL particles (pattern A) in 71% of the family members and a predominance of small, dense LDL particles (pattern B) in 29% of family members. Based on complex segregation analysis, pattern B appeared to be inherited as an autosomal trait with either a dominant or an additive mode of inheritance and a small, but significant, multifactorial inheritance component. The proposed allele for pattern B was common (frequency = 0.3), and reduced penetrance was observed among men under age 20 and among women under age 50. These results in these FCHL families are consistent with those from a previously reported population-based sample of families, in which pattern B showed an apparent dominant mode of inheritance. In that study, reduced penetrance was observed for men under age 20 and for premenopausal women, but a somewhat lower allele frequency was found for pattern B (0.25). In the FCHL family members, LDL subclass pattern B was associated with significantly increased plasma levels of apolipoprotein B and triglyceride and decreased high density lipoprotein cholesterol. In comparison with a group of controls, the FCHL family members with pattern A had similar mean triglyceride levels, but higher mean apolipoprotein B. Thus, in families with FCHL, a predominance of small, dense LDL particles appears to be inherited as a common, single-gene trait, which is closely associated with the higher plasma triglyceride levels found in these families. The increased plasma apolipoprotein B levels found in FCHL cannot, however, be accounted for by this proposed locus.

Colestipol-induced changes in LDL composition and metabolism. II. Studies in humans.

We investigated the effect of the bile acid sequestrant, colestipol hydrochloride, on the composition and metabolism of human low density lipoprotein (LDL). Colestipol treatment produced a disproportionate decrease in LDL cholesterol compared to LDL apoB, resulting in a significant decrease in the LDL cholesterol/apoB ratio. Electron microscopy revealed that LDL particles were smaller in size and analytical ultracentrifugation demonstrated that colestipol therapy selectively depleted larger, more buoyant LDL particles of Sf degrees 6-7. Thus, colestipol therapy produced LDL that were smaller in size, more dense, and characterized by a decreased cholesterol to protein ratio. To determine whether the altered LDL had different metabolic properties, autologous LDL was isolated from subjects before and during colestipol therapy and their fractional catabolic rates (FCR) were then simultaneously determined in the same patient while on therapy. Eight LDL turnover studies comparing the catabolism of LDL isolated during therapy (Rx-LDL) and LDL isolated off therapy (Con-LDL) were performed in six subjects. All subjects responded to colestipol treatment, with an average 29% fall in LDL cholesterol. In four of six subjects, and in six of eight studies, the FCR of Rx-LDL was substantially slower than that of Con-LDL. These studies demonstrate that a drug intervention may alter subpopulations of LDL particles in such a way that overall LDL composition is changed. This alteration may independently affect the intrinsic metabolic behavior of the LDL. We suggest that such drug- (or dietary-) induced changes in LDL composition need to be considered in kinetic studies designed to assess the overall impact of the perturbation being studied.