Low-density Lipoprotein Subclasses Research Articles

Effect of Ezetimibe on Low‐and High‐Density Lipoprotein Subclasses in Sitosterolemia

Sitosterolemia (STSL) is a rare sterol disease manifested by very high plasma phytosterols (PS) with normal to high total cholesterol (TC) levels and increased atherosclerosis risk. Low density lipoprotein (LDL), intermediate density lipoprotein (IDL) and very lowdensity lipoprotein (VLDL) cholesterols are proatherogenic while high density lipoprotein (HDL) cholesterol is antiatherogenic. Ezetimibe (EZ), a sterol absorption inhibitor, can reduce plasma PS and TC levels in STSL but its effect on lipoprotein subclasses has not been studied. We evaluated the effect of EZ on lipoprotein subclasses in STSL patients (pts, n=8) taken off EZ for 14 wks then placed on EZ (10 mg/d) for 14 wks. Serum total lipids and subfractions were measured enzymatically or with the Lipoprint system. Data (mean±SEM) were analyzed by paired t‐test. EZ reduced serum TC (‐13±4%, p=0.02), VLDL (‐24±4%, p=0.002) and total LDL (‐17±6%, p=0.03) levels vs off EZ. Reduced LDL values were due to decreased IDLB and C (‐22±7 and ‐21±8%, p<0.05), not to large, buoyant LDL subclasses (LDL1: ‐8±8%, p=0.23 and LDL2: +35±55%, p=0.17). LDL size did not change with EZ (275±0 vs 274±1 Å, p=0.18). EZ increased HDL levels (26±8%, p=0.008) due to increased intermediate (34±14%, p=0.02) and large (33±16%, p=0.06) HDL subclasses. These data suggest EZ can favorably affect LDL and HDL subfractions distribution, thus providing potential clinical benefit in STSL beyond reducing TC and PS accrual.Funded by NIH and CIHR

Plasma lipidomics discloses metabolic syndrome with a specific HDL phenotype.

Lipidomics reveals a remarkable diversity of lipids in human plasma. In this study, we have performed an in-depth lipidomic analysis of human plasma from healthy individuals and subjects with metabolic syndrome (MetS) in order to determine the lipidomic profile that allows prognosis of a pathological subpopulation with altered high-density lipoprotein (HDL) metabolism. The MetS population was categorized as having pathological or nonpathological HDL. Anthropometric parameters, cardiovascular risk markers, and lipoprotein subclasses of HDL and low-density lipoproteins were also evaluated. Lipidomic analysis revealed 357 differential molecules that were clustered (k means) in the two groups. The molecules identified in the whole lipidome showed that MetS subjects presented lower levels of glycerolipids and higher levels of glycerophospholipids with respect to control subjects. In contrast, when only statistically differential lipids were taken into account, differences were found between the two groups in almost cases. Furthermore, levels of saturated fatty acids were higher in patients with pathological HDL levels than in controls, whereas levels of unsaturated fatty acids were lower. These results highlight the potential of lipidomics as a clinical tool for risk assessment and monitoring of disease.

Association of small, dense low-density lipoprotein cholesterol and galectin-3 in patients with chronic kidney disease

Background. Dyslipidemia is a common feature of chronic kidney disease (CKD). Although it has been observed that the pattern of lipid abnormalities can vary according to the stage of CKD, there is lack of data concerning the distribution of lipoprotein subclasses at various stages of the disease. In addition, association of proatherogenic small, dense low-density lipoprotein (sdLDL) subclasses with markers of inflammation, such is galectin-3, is not sufficiently explored. The aim of this study was to analyze concentrations and relative proportions of sdLDL-cholesterol (sdLDL-C) and galectin-3 in patients with CKD, with respect to the stage of the disease. Also, we sought possible independent associations of galectin-3 and sdLDL-C. Methods. The study involved 100 hemodialysis (HD) and 50 pre-dialysis patients, together with 94 healthy individuals. SdLDL-C was measured by heparin–magnesium precipitation method. Galectin-3 was measured by ELISA technique. Results. Galectin-3 levels were higher in pre-dialysis and HD patients than in the control group (p < 0.01). The concentration of sdLDL-C was highest in the pre-dialysis group and lowest in HD patients (p < 0.01). CKD patients with increased galectin-3 concentrations had significantly higher relative proportions of cholesterol in sdLDL (% sdLDL-C) than their counterparts with lower galectin-3 levels (p < 0.05). Relative proportion of sdLDL-C was shown to be an independent determinant of galectin-3 concentration. Conclusions. Our results demonstrated alterations in concentrations and proportions of sdLDL-C according to the stages of CKD. The observed independent associations of % sdLDL-C and galectin-3 provide further insight into their complex interaction during the progression of atherosclerosis in CKD.

Less but better: cardioprotective lipid profile of patients with GCK-MODY despite lower HDL cholesterol level

Patients with diabetes caused by single-gene mutations generally exhibit an altered course of diabetes. Those with mutations of the glucokinase gene (GCK-MODY) show good metabolic control and low risk of cardiovascular complications despite paradoxically lowered high-density lipoprotein (HDL) cholesterol levels. In order to investigate the matter, we analyzed the composition of low-density lipoprotein (LDL) and HDL subpopulations in such individuals. The LipoPrint© system (Quantimetrix, USA) based on non-denaturing, linear polyacrylamide gel electrophoresis was used to separate and measure LDL and HDL subclasses in fresh-frozen serum samples from patients with mutations of glucokinase or HNF1A, type 1 diabetes (T1DM) and healthy controls. Fresh serum samples from a total of 37 monogenic diabetes patients (21 from GCK-MODY and 16 from HNF1A-MODY), 22 T1DM patients and 15 healthy individuals were measured in this study. Concentrations of the small, highly atherogenic LDL subpopulation were similar among the compared groups. Large HDL percentage was significantly higher in GCK-MODY than in control (p = 0.0003), T1DM (p = 0.0006) and HNF1A-MODY groups (p = 0.0246). Patients with GCK-MODY were characterized by significantly lower intermediate HDL levels than controls (p = 0.0003) and T1DM (p = 0.0005). Small, potentially atherogenic HDL content differed significantly with the GCK-MODY group showing concentrations of that subfraction from control (p = 0.0096), T1DM (p = 0.0193) and HNF1A-MODY (p = 0.0057) groups. Within-group heterogeneity suggested the existence of potential gene–gene or gene–environment interactions. GCK-MODY is characterized by a strongly protective profile of HDL cholesterol subpopulations. A degree of heterogeneity within the groups suggests the existence of interactions with other genetic or clinical factors.

Interrelated cathepsin S-lowering and LDL subclass profile improvements induced by atorvastatin in the plasma of stable angina patients.

We hypothesized that, in stable angina patients, atorvastatin therapy lowers the cathepsin S (CTSS) concentrations, as assessed non-invasively according to a plasma analysis. In addition, the low-density lipoprotein (LDL) and high-density lipoprotein (HDL) size and subclasses in the plasma were analysed to establish the association between CTSS and lipoprotein metabolism and determine whether this association is atorvastatin-sensitive. A total of 43 patients with stable angina received atorvastatin therapy (20 mg/day, 10 weeks). The plasma CTSS mRNA levels, CTSS protein concentrations and CTSS activity, as well as LDL and HDL size and subclasses, were analysed before and after treatment. Atorvastatin treatment did not change the plasma CTSS mRNA levels, although it lowered the plasma CTSS concentrations and activity. An increased plasma CTSS concentration and activity were found to be associated with a more atherogenic LDL subclass profile (a decreased dominant LDL size and increased percentage of small, dense LDL particles). The atorvastatin-induced CTSS-loweringeffect was concomitant with an improvement in the LDL subclass profile, and the changes were found to be interrelated. Concomitant, interrelated changes in the CTSS levels and LDL subclass profiles were found in the LDL phenotype B patients only (a dominant LDL diameter of ≤ 25.5 nm at the start of the study). In this subgroup, lowering of the plasma CTSS mRNA level also correlated with lowering of the proportion of small, dense LDL particles. Atorvastatin-induced CTSS-lowering and LDL subclass profile improvements in the plasma of LDL phenotype B patients with stable angina are concomitant and interrelated.

Small-dense low-density lipoproteins are the predominant apoB-100-containing lipoproteins in cord blood

ObjectivesLow density lipoprotein (LDL)-cholesterol level in cord blood is approximately 30%. The aim of our study was to specifically explore LDL apoB distribution across sizes in cord blood serum. Design and methodsWe studied 83 healthy neonates and 17 paired healthy mothers. Plasma glucose and serum lipids, such as low-density lipoprotein (LDL) cholesterol (LDL-C), HDL cholesterol (HDL-C) and triglycerides (TG), were measured using enzymatic methods. Distribution of apoB-100 was performed by western blot and immunodetection on native 4–12% polyacrylamide gels. LDL subclasses were analyzed by Lipoprint-LDL. ResultsNeonates show the expected lower content of apoB LDL and small dense LDL is the predominant apoB containing particle: 67±7%. However, only 1.5% is sdLDL by Lipoprint. Maternal serum contains a large proportion of apoB in smaller LDL, 47±6% as compared to non-pregnant women, 6±1%, p<0.001. ConclusionsNeonates show the expected lower content of apoB–LDL but in an inverse distribution; sdLDL being the predominant particle. This novel finding for apoB sdLDL is consistent with previous data on HPLC studies showing increased middle and small-sized LDL lipid content in neonates as compared to adults which amounts to 84% of total LDL. Comparison of the results with Lipoprint LDL (lipids) with gradient gel electrophoresis native western blot (apoB-100) suggests that neonates carry fractions of small LDL that are comparatively poor in lipids as compared with their mothers. Further studies are warranted on the issue of sdLDL in neonates.

Distribution of Low-Density Lipoprotein and High-Density Lipoprotein Subclasses in Patients With Sarcoidosis

Systemic inflammatory diseases are associated with proatherogenic lipoprotein profile, but there is a lack of information regarding overall distributions of lipoprotein subclasses in sarcoidosis. To investigate whether patients with sarcoidosis have altered distributions of plasma low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles. Seventy-seven patients with biopsy-proven sarcoidosis (29 with acute and 48 with chronic sarcoidosis) treated with corticosteroids and 77 age- and sex-matched controls were included in the study. Low-density lipoprotein and HDL subclasses were determined by gradient gel electrophoresis, while inflammatory markers and lipid parameters were measured by standard laboratory methods. Compared to controls, patients had fewer LDL I subclasses (P < .001), but more LDL II and III (P < .001) subclasses. This pattern was evident in both acute and chronic disease groups. Patients also had smaller HDL size (P < .001) and higher proportions of HDL 2a (P = .006) and 3a particles (P = .004). Patients with chronic sarcoidosis had smaller LDL size than those with acute disease (P = .02) and higher proportions of HDL 3a subclasses (P = .04) than controls. In acute sarcoidosis, relative proportions of LDL and HDL particles were associated with levels of inflammatory markers, whereas in chronic disease an association with concentrations of serum lipid parameters was found. The obtained results demonstrate adverse lipoprotein subfraction profile in sarcoidosis with sustained alterations during disease course. Evaluation of LDL and HDL particles may be helpful in identifying patients with higher cardiovascular risk, at least for prolonged corticosteroid therapy due to chronic disease course.

Association of glutathione-S-transferase gene polymorphism and lipoprotein subclasses in hemodialysis patients

ObjectivesEnd-stage renal disease (ESRD) is characterized by profound dyslipidemia and enhanced oxidative stress. The patients also show evidence of exhausted and/or deficient anti-oxidative defense enzymes, one of them being glutathione-S-transferase (GST). This study investigates relationship between GST gene polymorphism and low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subclasses in ESRD. Design and methodsGSTM1, T1, and P1 genotypes were determined by polymerase chain reaction–restriction fragment length polymorphism in 160 patients undergoing hemodialysis. LDL and HDL subclasses were separated by gradient gel electrophoresis and biochemical parameters were measured by routine laboratory methods. ResultsGSTM1-positive patients had higher proportion of small, dense LDL III particles than those with GSTM1-null genotype (P<0.05). Similarly, GSTP1-Ile/Ile patients had higher proportion of LDL III (P<0.05), but more HDL 2b and less HDL 3a particles than GSTP1-Ile/Val and Val/Val carriers (P<0.05). LDL subclass distribution in smokers with GSTM1-null genotype was shifted towards smaller particles, as compared to GSTM1-positive and GSTM1-null non-smokers. Smokers with GSTP1-Ile/Val and Val/Val genotypes had smaller LDL size than their non-smoking counterparts (P<0.05). Both smokers and non-smokers with GSTP1 Ile/Ile genotype had more LDL III particles than non-smokers carrying Val allele. Non-smokers with GSTP1 Ile/Ile genotype had more HDL 2b subclasses than non-smokers with GSTP1-Ile/Val and Val/Val (P<0.05), but less HDL 3a particles than smokers with GSTP1-Ile/Val and Val/Val genotypes (P<0.05). GSTT1 gene polymorphism had no effect on lipoprotein subclass distributions. ConclusionsOur results demonstrate significant associations between low activity GST genotypes and proatherogenic lipoprotein particles in hemodialysis patients which might further increase their cardiovascular disease risk.

Serum low density lipoprotein subclasses in asthma

The levels of serum low-density lipoproteins (LDL) have been implicated in the inflammatory cascade in a murine model of asthma. Recent findings suggest that LDL may modulate the inflammatory state of the asthmatic airways in humans. We explored whether LDL subclasses are associated with the occurrence and severity of asthma. 24 asthmatics (M/F: 11/13) and 24 healthy individuals, with normal BMI and absence of metabolic syndrome, matched for age and gender. Serum concentrations of LDL subclasses were distributed as seven bands (LDL-1 and -2 defined as large, least pro-inflammatory LDL, and LDL-3 to -7 defined as small, most pro-inflammatory LDL), using the LipoPrint(©) System (Quantimetrix Corporation, Redondo Beach, CA, USA). LDL-1 was similar in the two groups (56 ± 16% vs. 53 ± 11, p = NS), while LDL-2 was significantly lower in asthmatics as compared to controls (35 ± 8% vs. 43 ± 10%, p = 0.0074). LDL-3 levels were two-fold higher in the asthmatics, but the difference did not reach the statistical significance (8 ± 7.3% vs. 4 ± 3%, p = NS). Smaller subclasses LDL-4 to LDL-7 were undetectable in controls. In asthmatics, LDL-1 was positively associated with VC% predicted (r = +0.572, p = 0.0035) and FEV1% predicted (r = +0.492, p = 0.0146). LDL-3 was inversely correlated with both VC% predicted (r = -0.535, p = 0.0071) and FEV1% predicted (r = -0.465, p = 0.0222). The findings of this pilot study suggest a role of LDL in asthma, and advocate for larger studies to confirm the association between asthma and dyslipidemia.

Smaller HDL particles are associated with absence of obstructive coronary artery disease in stable angina pectoris patients

A research on novel cardiovascular risk factors is mainly focused on patients with clinically verified coronary artery disease (CAD), while less is known about their presence in symptomatic patients, but without angiographically proven occlusion of coronary arteries. The aim of this study was to compare plasma low-density lipoprotein (LDL) and high-density lipoprotein (HDL) size and subclasses in stable angina patients with and without significant obstructive CAD. LDL and HDL subclasses were analysed in 100 stable angina patients with ≥50% of obstruction and 40 patients with less than 50% of luminal narrowing, as assessed by coronary angiography. Patients with <50% of obstruction had reduced mean HDL size and higher proportion of small HDL particles (P < 0.05). HDL size and proportion of small HDL particles were significant and independent predictors of obstructive CAD (P < 0.05, respectively). Stable angina patients with <50% of coronary obstruction have more favourable HDL subclasses distribution than patients with significant coronary stenosis.

Effects of chitosan on plasma lipids and lipoproteins: a 4-month prospective pilot study.

Chitosan can favorably modulate plasma lipids, but the available data are not conclusive. We evaluated the effect of chitosan on plasma lipids and lipoproteins in 28 patients with plasma triglyceride levels >150 mg/dL (mean age: 63 ± 12 years), not taking other lipid-lowering agents. All patients received a chitosan derived from fungal mycelium (Xantonet, Bromatech, Italy) at a fixed dose of 125 mg/d in addition to their current medications for 4 months. Polyacrylamide gel electrophoresis was used to measure low-density lipoprotein (LDL) subclasses. After treatment, total cholesterol reduced by 8%, LDL cholesterol by 2%, and triglycerides by 19%, with a concomitant 14% increase in high-density lipoprotein cholesterol. We also found a beneficial effect of chitosan on LDL subclasses, with a significant increase in LDL-2 particles (from 37 ± 8% to 47 ± 8%, P = .0001) and a decrease (although not significant) in atherogenic small, dense LDL. Whether these findings may affect cardiovascular risk remains to be established in future studies.

Impaired Fasting Glucose and Impaired Glucose Tolerance Have Distinct Lipoprotein and Apolipoprotein Changes: The Insulin Resistance Atherosclerosis Study

Cardiovascular risk is increased in individuals with impaired glucose tolerance (IGT) and impaired fasting glucose (IFG); however, those with IGT appear to be at greater risk. Lipoprotein abnormalities occur also in the prediabetic state. The authors examined lipoprotein composition in IGT and IFG. Cross-sectional analysis of a large epidemiological study was done. The Insulin Resistance Atherosclerosis Study had a total of 1107 participants. Lipoproteins and apolipoproteins were measured by conventional methods and lipoprotein composition by nuclear magnetic resonance spectroscopy. Compared with normal glucose tolerance, apolipoprotein B (105.2 vs 99.8 mg/dL, P < .05) was high in isolated IFG, triglyceride (1.48 vs 1.16 mmol/L, P < .001) was high in isolated IGT, and high-density lipoprotein cholesterol was low in combined IFG/IGT (1.12 vs 1.26 mmol/L, P < .001). Nuclear magnetic resonance spectroscopy revealed additional changes: increased total low-density lipoprotein (LDL) particles (1190 vs 1096 nmol/L, P < .01) in isolated IFG; increased large very-low-density lipoprotein (3.61 vs 2.47 nmol/L, P < .01) and small LDL subclass particles (665 vs 541 nmol/L, P < .05) and decreased large LDL subclass particles (447 vs 513 nmol/L, P < .01) in isolated IGT; and decreased large high-density lipoprotein subclass particles in combined IFG/IGT (4.24 vs 5.39 μmol/L, P < .001). Isolated IFG is characterized by increased apolipoprotein B and total LDL particles, whereas isolated IGT is associated with increased triglycerides, large very-low-density lipoprotein subclass particles, and structural remodeling of LDL particles. These results may help to explain differences in cardiovascular disease risk in the prediabetic state.

Size and Subclasses of Low-Density Lipoproteins

Size and Subclasses of Low-Density Lipoproteins

Effects of 12 months of treatment with disease-modifying anti-rheumatic drugs on low and high density lipoprotein subclass distribution in patients with early rheumatoid arthritis: a pilot study

Objectives: Patients with rheumatoid arthritis (RA) have increased cardiovascular risk. The aim of the present study was the assessment of low density lipoprotein (LDL) and high density lipoprotein (HDL) subclass distribution in patients with early RA (ERA, n = 30) compared with age- and sex-matched healthy subjects (n = 30), as well the effect of treatment for 12 months with the disease-modifying anti-rheumatic drugs (DMARDs) methotrexate and prednisone in this distribution.Method: LDL and HDL subclass distribution was determined using a polyacrylamide gel-tube electrophoresis method.Results: ERA patients exhibited increased levels of inflammatory markers and high disease activity score. ERA patients had higher serum levels of total cholesterol (TC), LDL cholesterol (LDL-C), and triglycerides (TG) whereas their serum HDL cholesterol (HDL-C) levels were significantly lower compared with controls. ERA patients exhibited significantly higher plasma levels of small dense LDL-C (sdLDL-C), leading to a significantly decreased mean LDL diameter. ERA patients had significantly decreased small HDL particles (HDL-3) concentration whereas serum levels of large HDL particles (HDL-2) did not differ compared with controls. Treatment with DMARDs resulted in a significant decrease in inflammatory markers and disease activity, along with a significant increase in HDL-C serum levels. The concentration of sdLDL-C did not change significantly during treatment. We observed a significant increase in the levels of large HDL-2 whereas the concentration of small HDL-3 did not significantly change.Conclusions: Patients with ERA have increased sdLDL-C levels and decreased HDL-C levels because of decreased concentration of the small HDL-3 subclass. The administration of DMARDs induced a significant increase in HDL-C levels, which was attributed to the increase in large HDL-2 serum concentration.

Association of Lipoprotein Subfractions and Coronary Artery Calcium In Patient at Intermediate Cardiovascular Risk

More precise estimation of the atherogenic lipid parameters could improve identification of residual risk beyond what is possible using traditional lipid risk factors. The aim of the present study was to explore the association between advanced analysis of lipoprotein subfractions and the prevalence of coronary artery calcium. Consecutive participants at intermediate cardiovascular risk who were undergoing computed tomographic assessment of coronary calcium (calcium score) were included. Using a validated ultracentrifugation method (the vertical autoprofile II test), cholesterol in eluting lipoprotein subfractions [i.e., low- (LDL), very-low-, intermediate-, and high-density lipoprotein subclasses, lipoprotein (a), and predominant LDL distribution] was directly quantified. A total of 410 patients were included (29% women, mean age 57 years), of whom 297 (72.4%) had coronary artery calcium. LDL pattern B (predominance of small dense particles) emerged as an independent predictor of coronary calcium after adjustment for traditional risk factors (odds ratio 4.46, 95% confidence interval 1.19 to 16.7). However, after additional stratification for dyslipidemia, as defined by conventional lipid profiling, a statistically significant prediction was only retained for high-density lipoprotein subfraction 2 (odds ratio 3.45, 95% confidence interval 2.03 to 50.1) and "real" LDL (odds ratio 6.10, 95% confidence interval 1.26 to 23.41) in the normolipidemia group and for lipoprotein (a) (odds ratio 7.81, 95% confidence interval 1.41 to 43.5) in the dyslipidemic group. In conclusion, advanced assessment of the lipoprotein subfractions [i.e., LDL pattern B, high-density lipoprotein subfraction 2, "real" LDL, and lipoprotein (a)] using the vertical autoprofile II test provided additional information to that of conventional risk factors on the prevalence of coronary artery calcium in patients at intermediate cardiovascular risk.

Tracking fatty acid kinetics in distinct lipoprotein fractions in vivo: a novel high-throughput approach for studying dyslipidemia in rodent models

Isotopic tracers have been used to examine lipid trafficking for many years, and data from those studies have typically yielded novel insight regarding the pathophysiology of dyslipidemia. Previous experimental designs were suitable for studies in humans because relatively large volumes of plasma could be regularly sampled. We have expanded on the earlier logic by applying high-throughput analytical methods that require reduced sample volumes. Specifically, we have examined the possibility of coupling gel-based separations of lipoproteins (e.g., lipoprint) with LC-MS/MS analyses of complex lipid mixtures as a way to routinely measure the labeling profiles of distinct lipids in discrete lipoprotein subfractions. We demonstrate the ability to measure the incorporation of [U-(13)C]oleate into triglycerides (TG), PLs (PL), and cholesterol esters (CE) in VLDL, LDL, and HDL particles in mice. Although rodent models of dyslipidemia are inherently different from humans because of alterations in enzyme activities and underlying metabolism, rodent models can be used to screen novel compounds for efficacy in altering a given biochemical pathway and therein enable studies of target engagement in vivo. We expect that it is possible to translate our approach for application in other systems, including studies in humans.

LDL subclasses and lipoprotein-phospholipase A2 activity in suppressed HIV-infected patients switching to raltegravir: Spiral substudy

ObjectiveTo analyze the effect of switching the ritonavir-boosted protease inhibitor (PI/r) in a stable combined antiretroviral therapy (cART) regimen to raltegravir on low-density lipoprotein (LDL) particles, and lipoprotein-associated phospholipase A2 (Lp-PLA2). DesignSubstudy of a multicenter randomized trial that compared the efficacy of switching a PI/r to raltegravir-based cART in stable HIV-infected patients. MethodsLDL size and phenotype (by gel-gradient electrophoresis), Lp-PLA2 (by 2-thio-PAF [Cayman]), proprotein convertase subtilisin/kexin type 9 (PCSK9) (by ELISA), and standard lipid parameters were measured at baseline and week 48. ResultsEighty-one (PI/r n = 41 and raltegravir n = 40) patients were evaluated. No differences in baseline demographic and metabolic variables between arms were found except in apolipoprotein (Apo) B (p = 0.042). At week 48, total cholesterol (TC) (p < 0.001), LDL-c (p = 0.023), non-high density lipoprotein cholesterol non-high-density lipoprotein cholesterol (non-HDL-c) (p < 0.001), TC/HDL (p = 0.026), triglyceride (p < 0.001), Apo B (p < 0.001), Apo A-I (p = 0.004) and Lp (a) (p = 0.005) decreased in raltegravir arm compared to PI/r arm. At week 48, a shift from LDL phenotype B to the less atherogenic phenotype A was observed only in raltegravir arm (p < 0.001). LDL size increased (PI/r 2.1 nm, p = 0.019; raltegravir 3.8 nm, p = 0.001) and cholesterol content in small and dense LDL subfractions (LDL 4,5,6) decreased (PI/r p = 0.007, raltegravir p = 0.006) at week 48 in both arms. Total Lp-PLA2 activity (PI/r p = 0.037 and raltegravir p = 0.051) and PCSK9 plasma concentration decreased in both arms (PI/r p = 0.034 and raltegravir p < 0.001). ConclusionsSwitching a PI/r to a raltegravir-based cART in virologically suppressed HIV-infected patients was associated with an overall improvement in lipid profile, including a shift to a less atherogenic LDL phenotype.

Effects of dietary saturated fat on LDL subclasses and apolipoprotein CIII in men

Background/ObjectivesSmall dense LDL particles and apolipoprotein (apo) CIII are risk factors for cardiovascular disease (CVD) that can be modulated by diet, but there is little information regarding the effects of dietary saturated fat on their plasma levels. We tested the effects of high vs. low saturated fat intake in the context of a high beef protein diet on levels and composition of LDL subclasses and on apoCIII levels in plasma and LDL.Subjects/MethodsFollowing consumption of a baseline diet (50% CHO, 13% protein, 38% total fat, 15% saturated fat) for 3 wk, 14 healthy men were randomly assigned to two reduced carbohydrate high beef protein diets (31% CHO, 31% protein, 38% fat) that differed in saturated fat content (15% vs. 8%) for 3 wk each in a crossover design.ResultsThe high saturated fat diet resulted in higher mass concentrations of buoyant LDL I, medium density LDL II and dense LDL III, but not the very dense LDL IV; and significant increases in plasma and LDL apoCIII concentration of 9.4% and 33.5%, respectively. The saturated fat-induced changes in LDL apoCIII were specifically correlated with changes in apoCIII content of LDL IV.ConclusionsTaken together with previous observations, these findings suggest that, at least in the context of a lower carbohydrate high beef protein diet, high saturated fat intake may increase CVD risk by metabolic processes that involve apoCIII.

Anomalous lipoprotein-X in type 2 diabetes mellitus

Type 2 diabetes mellitus (DM2) is the most common form of diabetes characterized by the disturbances of carbohydrate, protein, and lipid metabolism including dyslipidemia and elevation of the low-density lipoprotein (LDLP) levels. Lipoprotein-X (LP-X) represents an anomalous subclass of LDLP a distinctive feature of which is the high content of phospholipids and non-esterified cholesterol coupled with the low level of cholesterol ethers, triglycerides, and proteins. LP-X was detected in the blood of the patients with various diseases of the liver and biliary ducts associated with cholestasis. The results of our previous investigations suggest the presence of LP-X in the blood of the patients with familial Mediterranean fever and ischemic stroke complicated by concomitant diabetes mellitus. The objective of the present work was to elucidate whether LP-X actually occurs in the blood of the patients presenting with type 2 diabetes mellitus. We used the method of polyanionic precipitation of LDLP preliminarily separated by agar gel electrophoresis. The study has demonstrated for the first time the presence of LP-X in the blood of the patients with type 2 diabetes mellitus. Its possible pathogenetic role and mechanisms of LP-X generation in DM2 are discussed.

Changes in LDL and HDL Subclasses in Normal Pregnancy and Associations with Birth Weight, Birth Length and Head Circumference

Pregnancy is associated with alterations in low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subclasses, but the exact pattern of these variations remains controversial. This study investigates longitudinal changes of plasma LDL and HDL particles distributions during the course of normal pregnancy, as well as associations of maternal LDL and HDL subclasses distributions before delivery with parameters of newborn size. Blood samples were collected from 41 healthy pregnant women throughout entire pregnancy, before delivery and 7 weeks postpartum. LDL and HDL subclasses were determined by gradient gel electrophoresis, while other biochemical parameters were measured by standard laboratory methods. During gestation LDL size significantly decreased (P < 0.001), due to reduction in relative proportion of LDL I (P < 0.01) and increase of LDL II (P < 0.001) and IIIA (P < 0.05) subclasses. In the same time, HDL size and proportions of HDL 2a particles significantly decreased (P < 0.001), with concomitant increase of HDL 3b and 3c subclasses (P < 0.05). Observed alterations were associated with changes in serum triglyceride levels. Rearrangement in LDL subclasses distribution during gestation was transient, while postpartum HDL subclasses distribution remained shifted toward smaller particles. Higher proportion of LDL IVB in maternal plasma before delivery was an independent predictor of smaller birth weights and lengths, while higher proportions of LDL IVB and HDL 2a subclasses were independent determinants of newborns' smaller head circumferences. Routine gestational and prenatal care in otherwise normal pregnancy could be complemented with evaluation of LDL and HDL particles distribution in order to ensure an adequate size of the newborn.