Intermediate-density Lipoprotein Research Articles

Apolipoprotein CIII Deficiency Protects Against Atherosclerosis in Knockout Rabbits.

Apo (apolipoprotein) CIII mediates the metabolism of triglyceride (TG)-rich lipoproteins. High levels of plasma apoCIII are positively correlated with the plasma TG levels and increase the cardiovascular risk. However, whether apoCIII is directly involved in the development of atherosclerosis has not been fully elucidated. Approach and Results: To examine the possible roles of apoCIII in lipoprotein metabolism and atherosclerosis, we generated apoCIII KO (knockout) rabbits using ZFN (zinc finger nuclease) technique. On a normal standard diet, apoCIII KO rabbits exhibited significantly lower plasma levels of TG than those of WT (wild type) rabbits while total cholesterol and HDL (high-density lipoprotein) cholesterol levels were unchanged. Analysis of lipoproteins isolated by sequential ultracentrifugation revealed that reduced plasma TG levels in KO rabbits were accompanied by prominent reduction of VLDLs (very-low-density lipoproteins) and IDLs (intermediate-density lipoproteins). In addition, KO rabbits showed faster TG clearance rate after intravenous fat load than WT rabbits. On a cholesterol-rich diet, KO rabbits exhibited constantly and significantly lower levels of plasma total cholesterol and TG than WT rabbits, which was caused by a remarkable reduction of β-VLDLs-the major atherogenic lipoproteins. β-VLDLs of KO rabbits showed higher uptake by cultured hepatocytes and were cleared faster from the circulation than β-VLDLs isolated from WT rabbits. Both aortic and coronary atherosclerosis was significantly reduced in KO rabbits compared with WT rabbits. These results indicate that apoCIII deficiency facilitates TG-rich lipoprotein catabolism, and therapeutic inhibition of apoCIII expression may become a novel means not only for the treatment of hyperlipidemia but also for atherosclerosis.

Daily mycoprotein consumption for 1 week does not affect insulin sensitivity or glycaemic control but modulates the plasma lipidome in healthy adults: a randomised controlled trial.

Mycoprotein consumption has been shown to improve acute postprandial glycaemic control and decrease circulating cholesterol concentrations. We investigated the impact of incorporating mycoprotein into the diet on insulin sensitivity (IS), glycaemic control and plasma lipoprotein composition. Twenty healthy adults participated in a randomised, parallel-group trial in which they consumed a 7 d fully controlled diet where lunch and dinner contained either meat/fish (control group, CON) or mycoprotein (MYC) as the primary source of dietary protein. Oral glucose tolerance tests were performed pre- and post-intervention, and 24 h continuous blood glucose monitoring was applied throughout. Fasting plasma samples were obtained pre- and post-intervention and were analysed using quantitative, targeted NMR-based metabonomics. There were no changes within or between groups in blood glucose or serum insulin responses, nor in IS or 24 h glycaemic profiles. No differences between groups were found for 171 of the 224 metabonomic targets. Forty-five lipid concentrations of different lipoprotein fractions (VLDL, LDL, intermediate-density lipoprotein and HDL) remained unchanged in CON but showed a coordinated decrease (7-27 %; all P < 0·05) in MYC. Total plasma cholesterol, free cholesterol, LDL-cholesterol, HDL2-cholesterol, DHA and n-3 fatty acids decreased to a larger degree in MYC (14-19 %) compared with CON (3-11 %; P < 0·05). Substituting meat/fish for mycoprotein twice daily for 1 week did not modulate whole-body IS or glycaemic control but resulted in changes to plasma lipid composition, the latter primarily consisting of a coordinated reduction in circulating cholesterol-containing lipoproteins.

Comparison of calculated remnant lipoprotein cholesterol levels with levels directly measured by nuclear magnetic resonance

BackgroundRemnant cholesterol (RC) can partly explain the residual risk in atherosclerotic cardiovascular disease (ASCVD). A consensus method of measuring RC levels has not been established yet. In clinical practice, RC levels are usually calculated from the standard lipid profile, which are not true RC. Nuclear magnetic resonance (NMR) can measure RC levels directly. This study aimed to characterize RC at fasting and non-fasting states in more details and establish the performance of calculated RC and NMR-measured RC.MethodsBlood samples at fasting state and at 2 h and 4 h postprandial states were collected in 98 subjects. Lipid parameters including total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), subfractions 3, 4, and 5 of very low-density lipoprotein cholesterol (VLDL3-C, VLDL4-C, and VLDL5-C, respectively), and intermediate-density lipoprotein cholesterol (IDL-C) were measured by enzymatic method and NMR. RC levels calculated from the standard lipid profile or measured by NMR were referred here as RCe or RCn.ResultsThe RCe and RCn levels were different, but both of them increased after a meal (P < 0.05), especially at 4 h postprandial state. Low correlations were found between RCe and RCn in the 1st, 2nd, and 3rd quartiles of TG, but RCn showed great correlation with RCe in the highest quartile regardless of the fasting or non-fasting state (R = 0.611, 0.536, and 0.535 for 0 h, 2 h, and 4 h, respectively). However, across the 2nd and 3rd quartiles, RCe levels were nearly close to RCn levels. RCe levels tended to overestimate RCn levels in the 1st quartile of TGe levels with median differences of 0.23(− 0.13, 0.63) and underestimate RCn levels with median differences of − 0.23(− 0.33, 0.07) in the highest quartile of TGe levels.ConclusionsRC calculated from the standard lipid profile as TC minus LDL-C minus HDL-C is different from the NMR-measured RC. According to different TG levels, RC could overestimate or underestimate the actual RC level. Developing a consensus clinical method to measure RC levels is necessary, so that results from different studies and platforms can be more directly compared.Trial registrationChinese Clinical Trial Registry, ChiCTR1900020873. Registered in 21 January 2019 - Retrospectively registered.

Effect of the Fat Eaten at Breakfast on Lipid Metabolism: A Crossover Trial in Women with Cardiovascular Risk.

Recent studies point out that not only the daily intake of energy and nutrients but the time of day when they are ingested notably regulates lipid metabolism and cardiovascular risk (CVR). Therefore, the aim of the study was to assess if the type of fat ingested at breakfast can modify lipid metabolism in women with CVR. A randomized, crossover clinical trial was performed. Sixty volunteers were randomly assigned to a (A) polyunsaturated fatty acid (PUFA)-rich breakfast, (B) saturated fatty acid (SFA)-rich breakfast, or (C) monounsaturated fatty acid (MUFA)-rich breakfast. Plasma lipoprotein and apolipoprotein subfractions were determined. Our data showed that the PUFA-rich breakfast decreased lipoprotein (a) (Lp(a)), very low-density lipoproteins (VLDL), and intermediate-density lipoproteins (IDL), and increased high-density lipoproteins (HDL). A similar trend was observed for the MUFA-rich breakfast, whereas the SFA-rich breakfast, although it decreased VLDL, also increased IDL and reduced HDL. The PUFA-rich breakfast also decreased β-lipoproteins and apolipoprotein-B. In summary, varying the type of fat eaten at breakfast is enough to significantly modify the lipid metabolism of women with CVR, which can be of great relevance to establish new therapeutic strategies for the treatment of these subjects.

P1581IMPACT OF ACHIEVING LDL CHOLESTEROL LOWER THAN 100 MG/DL WITH STATINS, ON LIPID PROFILE AND INFLAMMATION IN END-STAGE RENAL DISEASE PATIENTS

Abstract Background and Aims Dyslipidemia is common in chronic kidney disease (CKD) and cardiovascular disease (CVD)-related events are the main causes of death in end-stage renal disease (ESRD) patients on dialysis. Concerning lipid management, clinical practice emphasized treatment escalation to achieve specific low-density lipoprotein cholesterol (LDLc) targets, which implies repeated LDLc evaluations, and enhancement of statin doses or combination of lipid-lowering therapies. However, the LDLc target is not consensual, with some entities suggesting 100 mg/dl and others a more conservative level. It has been hypothesized that lipoprotein’s quality (size, composition and functionality) may be more important than their total circulating levels, as CVD risk factor. Our aim was to evaluate and compare, in ESRD patients on dialysis and under statins treatment, the levels of lipoprotein fractions and subfractions and inflammatory markers, between patients who achieved LDLc levels &amp;lt; 100 mg/dl and those who did not achieve that target. Method We studied 110 ESRD patients on dialysis (high-flux hemodialysis or hemodiafiltration) and under statin therapy; 87 presented a LDLc &amp;lt; 100 mg/dl (group 1) and 23 a value &amp;gt; 100 mg/dl (group 2); levels of high-sensitivity C-reactive protein (hsCRP), interleukin(IL)-6, lipid profile including lipoprotein fractions/subfractions, and oxidized LDL (oxLDL) were evaluated. Results Group 1, as compared to group 2, presented lower values of total cholesterol (TC), triglycerides, oxLDL, TC/high-density lipoprotein cholesterol (HDLc) and LDLc/HDLc ratios. Concerning lipoprotein fractions/subfractions, group 1 presented significantly higher larger and intermediate LDL, and a trend towards lower small LDL (P=0.063), higher large HDL (P=0.069) and lower small HDL (P=0.080); no significant alterations were found for very-low-density lipoprotein and intermediate-density lipoprotein. Regarding inflammatory markers, no significant differences were observed between the 2 groups. Conclusion Patients who achieved the LDLc &amp;lt; 100 mg/dl target presented a better non-conventional lipid profile, including lower oxLDL levels and an increase in larger (less atherogenic) LDL subfractions. According to our data, a lower LDLc level associates with a better lipid profile; the benefits of this improvement on HDL fractions and CVD-related events in ESRD patients on dialysis needs to be better clarified.

Association between Very Low-Density Lipoprotein Cholesterol (VLDL-C) and Carotid Intima-Media Thickness in Postmenopausal Women Without Overt Cardiovascular Disease and on LDL-C Target Levels.

Background: atherosclerotic process inexorably advances in patients reaching low-density lipoprotein cholesterol (LDL-C) targets. An attractive hypothesis is that lipoprotein particles (very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL)), could contribute to residual risk. The present study aims to investigate the relationship between carotid intima-media thickness (IMT) and different lipoprotein subfractions in a cohort of healthy postmenopausal women. Methods: 75 postmenopausal women, at LDL-C target levels without overt cardiovascular disease, underwent biochemical analyses (including subfraction assay of plasma lipoproteins) and carotid ultrasound examination. Results: a statistically significant correlation between VLDL and carotid IMT (p < 0.001) was found. No significant correlation was found between carotid IMT and LDL-C (p = 0.179), IDL-C (p = 0.815), high-density lipoprotein (HDL) (p = 0.855), and LDL score (p = 0.240). Moreover, IMT is significantly correlated to LDL particle diameter (p = 0.044). After adjusting for age, systolic blood pressure, body mass index, smoking habits, glucose plasma concentration, and Lipoprotein(a) (Lpa) levels, multivariate analysis showed that women in the third tertile of VLDL-C, compared with those in the first tertile, were significantly associated to the highest IMT (p = 0.04). Conclusions: in this cohort of postmenopausal women, VLDL-C was significantly associated to carotid IMT, independent of main cardiovascular risk factors. These findings pave the way for targeting circulating concentrations of VLDL-C to reduce cardiovascular events in patients with target LDL-C levels.

A comprehensive metabolic profiling of the metabolically healthy obesity phenotype

BackgroundThe ever-increasing prevalence of obesity constitutes a major health problem worldwide. A subgroup of obese individuals has been described as “metabolically healthy obese” (MHO). In contrast to metabolically unhealthy obese (MUO), the MHO phenotype has a favorable risk profile. Despite this, the MHO phenotype is still sub-optimally characterized with respect to a comprehensive risk assessment. Our aim was to increase the understanding of metabolic alterations associated with healthy and unhealthy obesity.MethodsIn this cross-sectional study, men and women (18–70 years) with obesity (body mass index (BMI) ≥ 30 kg/m2) or normal weight (NW) (BMI ≤ 25 kg/m2) were classified with MHO (n = 9), MUO (n = 10) or NW (n = 11) according to weight, lipid profile and glycemic regulation. We characterized individuals by comprehensive metabolic profiling using a commercial available high-throughput proton NMR metabolomics platform. Plasma fatty acid profile, including short chain fatty acids, was measured using gas chromatography.ResultsThe concentrations of very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) subclasses were overall significantly higher, and high density lipoprotein (HDL) subclasses lower in MUO compared with MHO. VLDL and IDL subclasses were significantly lower and HDL subclasses were higher in NW compared with MHO. The concentration of isoleucine, leucine and valine was significantly higher in MUO compared with MHO, and the concentration phenylalanine was lower in NW subjects compared with MHO. The fatty acid profile in MHO was overall more favorable compared with MUO.ConclusionsComprehensive metabolic profiling supports that MHO subjects have intermediate-stage cardiovascular disease risk marker profile compared with NW and MUO subjects.Clinical trial registration numberNCT01034436, Fatty acid quality and overweight (FO-study).Graphical abstract

SUN-571 The Associations Between p,p’-DDE Levels and Serum Levels of Lipoproteins and Their Subclasses in an Elderly Population Determined by Lipidomics Analysis

Low biodegradability and high lipophilicity of p,p’-dichlorodiphenyldichloroethylene (DDE), a metabolite of the insecticide DDT, leads to transport with lipids and accumulation in adipose tissue. This persistence allows for DDE to effect adipose tissue and lipid metabolism. A few small human studies have shown an association between DDE and blood lipids, although with some inconsistent conclusions. The aim of this study was to investigate the association between DDE exposure and altered levels of circulating lipids in a large human cohort. To evaluate the associations between DDE and human lipid profiles, plasma was collected from a subset of elderly Swedes in the Prospective Investigation of the Vasculature of Uppsala Seniors (PIVUS) cohort who were free from lipid lowering medication (n = 571). DDE concentrations in plasma were measured using high-throughput solid phase extraction and gas chromatography-high resolution mass spectrometry. Lipidomic analysis of plasma was performed with nuclear magnetic resonance spectroscopy. Linear models of lipids and DDE were statistically adjusted for sex and body mass index. Detectable levels of DDE were found in the plasma samples of all subjects. With elevated DDE levels, the comprehensive lipoprotein profile showed an elevation in total concentration of all diameters of very low density lipoprotein (VLDL) (p<0.001), low density lipoprotein (LDL) (p<0.008), intermediate density lipoprotein (IDL) (p<0.02), and in small high density lipoprotein (HDL) (p<0.05). Triglycerides and DDE were associated to varying degrees in lipoproteins (IDL > VLDL > LDL > HDL) and within total serum (p<0.005). DDE levels were positively associated with cholesterol and cholesterol ester levels only in VLDL and LDL (p<0.05) and with apolipoprotein B (p<0.0009). The positive associations observed between each lipoprotein class and elevated DDE support previous data suggesting that DDE interacts with lipoproteins within plasma. We speculate that both physio-chemical and biological mechanisms may explain why DDE does not uniformly associate with lipids across lipoproteins.

Regulation of Apolipoprotein B by Natural Products and Nutraceuticals: A Comprehensive Review.

Cardiovascular Disease (CVD) is the most important and the number one cause of mortality in both developing and industrialized nations. The co-morbidities associated with CVD are observed from infancy to old age. Apolipoprotein B100 (Apo B) is the primary apolipoprotein and structural protein of all major atherogenic particles derived from the liver including Very-Low- Density Lipoproteins (VLDL), Intermediate-density Lipoprotein (IDL), and Low-density Lipoprotein (LDL) particles. It has been suggested that measurement of the Apo B concentration is a superior and more reliable index for the prediction of CVD risk than is the measurement of LDL-C. Nutraceuticals and medicinal plants have attracted significant attention as it pertains to the treatment of non-communicable diseases, particularly CVD, diabetes mellitus, hypertension, and Nonalcoholic Fatty Liver Disease (NAFLD). The effect of nutraceuticals and herbal products on CVD, as well as some of its risk factors such as dyslipidemia, have been investigated previously. However, to the best of our knowledge, the effect of these natural products, including herbal supplements and functional foods (e.g. fruits and vegetables as either dry materials, or their extracts) on Apo B has not yet been investigated. Therefore, the primary objective of this paper was to review the effect of bioactive natural compounds on plasma Apo B concentrations. It is concluded that, in general, medicinal plants and nutraceuticals can be used as complementary medicine to reduce plasma Apo B levels in a safe, accessible, and inexpensive manner in an attempt to prevent and treat CVD.

Relationship of fibroblast growth factor 21 levels with inflammation, lipoproteins and non-alcoholic fatty liver disease

Background and aimsNon-alcoholic fatty liver disease (NAFLD) is associated with inflammation and atherogenic lipoprotein abnormalities. Previous studies suggest an association of fibroblast growth factor 21 (FGF21) with NAFLD. Therefore, we assessed the association of circulating FGF21 levels with inflammatory markers, lipoprotein profile and NAFLD in the Multi-Ethnic Study of Atherosclerosis (MESA). MethodsAmong 6814 participants free of apparent cardiovascular disease at baseline (2000–2002), 3634 participants had valid data on variables of interest. After excluding participants with excessive alcohol consumption, 3446 participants were included in the analysis. NAFLD was defined using non-contrast cardiac computed tomography with a liver-to-spleen ratio (LSR) < 1 or liver attenuation <40 Hounsfield units (HU). ResultsThe mean age of the participants was 63.5 years with 54% females, 36% Caucasian, 10% Chinese American, 31% African American and 23% Hispanic. 17% of the participants had NAFLD. After adjustment for demographic, socioeconomic and other confounders, a 1-SD increment in ln-transformed FGF21 level was associated with a 5.1% higher IL-6 level, a 0.31 nm larger very-low-density lipoprotein particle diameter, a 0.014 nm smaller high-density lipoprotein particle diameter, and a 5.25 nmol/L lower intermediate-density lipoprotein particle concentration (all p < 0.05). A 1-SD increment in ln-transformed FGF21 level was associated with LSR<1 and liver attenuation <40 HU (OR = 1.38 and 1.48; both p < 0.01), even after adjusting for the aforementioned inflammation and lipoprotein parameters. ConclusionsThis study suggests an association between FGF21 and NAFLD, independent of inflammation and atherogenic lipoprotein abnormalities. Further studies are needed to assess FGF21 as a biomarker for future NAFLD risk.

Comparison of nonfasting and fasting lipoprotein subfractions and size in 15,397 apparently healthy individuals: An analysis from the VITamin D and OmegA-3 TriaL

Elevated postprandial triglycerides reflect a proatherogenic milieu, but underlying mechanisms are unclear. We examined differences between fasting and nonfasting profiles of directly measured lipoprotein size and subfractions to assess if postprandial triglycerides reflected increases in very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and remnants, or small dense lipid depleted LDL (sdLDL) particles. We conducted a cross-sectional analysis of 15,397 participants (10,135 fasting; 5262 nonfasting [<8hours since last meal]) from the VITamin D and OmegA-3 TriaL. Baseline cholesterol subfractions were measured by the vertical auto profile method and particle subfractions by ion mobility. We performed multivariable linear regression adjusting for cardiovascular and lipoprotein-modifying risk factors. Mean age (SD) was 68.0years (±7.0), with 50.9% women. Adjusted mean triglyceride concentrations were higher nonfasting by 17.8±1.3%, with higher nonfasting levels of directly measured VLDL cholesterol (by 3.5±0.6%) and total VLDL particles (by 2.0±0.7%), specifically large VLDL (by 12.3±1.3%) and medium VLDL particles (by 5.3±0.8%), all P<.001. By contrast, lower concentrations of low density lipoprotein (LDL) and IDL cholesterol and particles were noted for nonfasting participants. sdLDL cholesterol levels and particle concentrations showed no statistically significant difference by fasting status (-1.3±2.1% and 0.07±0.6%, respectively, P>.05). Directly measured particle and cholesterol concentrations of VLDL, not sdLDL, were higher nonfasting and may partly contribute to the proatherogenicity of postprandial hypertriglyceridemia. These differences, although statistically significant, were small and may not fully explain the increased risk of postprandial hypertriglyceridemia.

Abstract P1-13-01: Lipoprotein and metabolite responses to physical exercise during adjuvant breast cancer treatment

Abstract Background: Adjuvant breast cancer treatment may cause metabolic perturbations, such as dyslipidaemia, potentially exacerbating risk of cardiometabolic disease as well as risk of breast cancer recurrence. Physical exercise may have beneficial metabolic effects, but it’s effect on serum lipoprotein- and metabolite profiles during adjuvant breast cancer treatment including chemotherapy is not yet well established. Methods: The women participating in this pilot study of Energy Balance and Breast Cancer Aspects (EBBA)-II, were aged 38-69 years and diagnosed with stage I-II breast cancer. 60 breast cancer patients were randomized after surgery to a control group (n = 29, usual care) or an intervention group (n = 31, intervention), stratified by menopausal status. The patients in the intervention group received a detailed exercise program and met for supervised training sessions in groups of 10-12 women for 60 minutes twice a week during a 12 month period, and were in addition asked to perform at least 60 minutes of exercise at home (a total of 180 minutes of exercise weekly). Fasting serum samples were collected pre-surgery and after six months, and analysed by nuclear magnetic resonance (NMR)-spectroscopy and mass spectrometry. 170 metabolites and 109 lipoprotein subclass variables were quantified and analysed using orthogonalized partial least squares discriminant analysis. Statistical significance was assessed by permutation testing. Single variables were tested with Mann Whitney U-tests or multiple linear regression (NCT02240836). Results: The breast cancer patients (n = 60) had at pre-surgery the following means: Age at diagnosis of 55.4 years (38-69 years), low density lipoprotein (LDL)-cholesterol 145.4 mg/dl (3.76 mmol/L), high density lipoprotein (HDL)-cholesterol 70.4 mg/dl (1.82 mmol/L), and triglycerides 101.9 mg/dl (1.15 mmol/L), and 58.3 % of the patients underwent chemotherapy (paclitaxel/docetaxel/5-FU/epirubicin/cyclophosphamide based adjuvant chemotherapy). Physical exercise ameliorated chemotherapy-induced increases in very low density lipoprotein (VLDL)- and intermediate density lipoprotein (IDL)-associated lipids, and reduced triglyceride enrichment in LDL and HDL compared with chemotherapy controls (p = 0.003). Physical exercise also significantly increased apoA1 (4.6 % increase vs 11.3 % decrease, q = 0.02) and apoA2 (5.2 % increase vs 13.0 % decrease, q = 0.01) compared with chemotherapy control patients. The NMR-measured lipid signal at 1.55-1.60 ppm increased after six months in chemotherapy recipients, but this was attenuated among chemotherapy recipients in the intervention group. No statistically significant effect of physical exercise on serum levels of small-molecular metabolites was detected. Conclusion: Our findings suggest that physical exercise may prevent atherogenic alterations in lipoprotein profile induced by chemotherapy. The results indicate increased HDL particle number- and function, as well as increased triglyceride clearance in the intervention group. Thus, atherogenic alterations in lipoprotein profile may play a role in evaluating breast cancer treatment, and could potentially be biomarkers of importance for breast cancer prognosis and co-morbidity. Citation Format: Torfinn Støve Madssen, Vidar Gordon Flote, Inger Thune, Gro Falkener Bertheussen, Anders Husøy, Steinar Lundgren, Hanne Frydenberg, Erik Wist, Ellen Schlichting, Jon Lømo, Anne McTiernan, Tone Frost Bathen, Guro Fanneløb Giskeødegård. Lipoprotein and metabolite responses to physical exercise during adjuvant breast cancer treatment [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P1-13-01.

Gender differences in LDL and HDL subfractions in atherogenic and nonatherogenic phenotypes

ObjectivesThe aim of our study was to examine the role of low density lipoprotein (LDL)-subfractions in individuals with the atherogenic and non-atherogenic phenotype and the gender differences in lipoprotein subfractions including small dense LDL (sdLDL) and small high density lipoprotein (sHDL) subfractions representing the most atherogenic lipoprotein subfractions. Design & methods35 persons in the atherogenic group (AG) (with sdLDL3–7 subfractions ≥6 mg/dl) and 104 individuals in the non-atherogenic group (NAG) (sdLDL3–7 subfractions <6 mg/dl) were included in our study. To analyze plasma lipoprotein subfractions, a polyacrylamide gel electrophoresis–the Lipoprint system was used. ResultsMales compared to females in the AG had significantly higher levels of atherogenic lipoprotein subfractions such as HDL8, HDL9 and HDL10. All participants in AG had significantly lower levels of intermediate density lipoprotein IDL-A than those in NAG but significantly higher levels of IDL-B and IDL-C. Males in the AG compared to NAG had significantly lower levels of LDL1 and higher levels of LDL2 and LDL3–7 subfractions. In the NAG LDL2 positively correlated with sHDL subfractions while in the AG with the large HDL subfraction. ConclusionResults of our study demonstrate more atherogenic profile in males compared to females and a double role of LDL2 subfraction in the atherogenic process depending on the phenotype (atherogenic/non-atherogenic) of individuals.

LIPA gene mutations affect the composition of lipoproteins: Enrichment in ACAT-derived cholesteryl esters

Background and aimsCholesteryl ester storage disease (CESD) due to LIPA gene mutations is characterized by hepatic steatosis, hypercholesterolemia and hypoalphalipoproteinemia, exposing affected patients to an increased cardiovascular risk. Further insights into the impact of LIPA gene mutations on lipid/lipoprotein metabolism are limited. Aim of the study was to investigate the effect of carrying one or two mutant LIPA alleles on lipoprotein composition and function. MethodsLipoproteins were isolated from 6 adult CESD patients, 5 relatives carrying one mutant LIPA allele (carriers) and 12 sex/age matched controls. Lipid profile, lipoprotein mass composition and the fatty acid distribution of cholesteryl esters (CEs) were assessed. HDL function was evaluated as the ability to promote nitric oxide release by endothelial cells. ResultsDespite the lipid-lowering therapy, total cholesterol, LDL-cholesterol and triglycerides were increased in CESD patients compared to controls, while HDL-cholesterol was reduced. Carriers also displayed elevated total and LDL-cholesterol. Very low and intermediate density lipoproteins from CESD patients and carriers were enriched in CEs compared to the control ones, with a concomitant reduction of triglycerides. Fatty acid composition of CEs in serum and lipoproteins showed a depletion of linoleate content in CESD patients, due to the reduced LCAT activity. In CESD HDL, fatty acid distribution of CEs was shifted towards saturated ones, if compared to control HDL. The changes in HDL composition did not affect HDL ability to promote nitric oxide release by endothelial cells. ConclusionsLIPA gene mutations significantly affected plasma levels and lipid composition of lipoproteins, likely contributing to the increased cardiovascular risk of affected patients.

Estimation of non-high-density lipoprotein cholesterol and its correlation as a surrogate measure of apolipoprotein B in patients with metabolic syndrome

Background: The primary target of therapy for dyslipidemia according to the present lipid guidelines is low-density lipoprotein cholesterol (LDL-C). Its main drawback is it is a derived value and erroneous values may be obtained if triglyceride values are high. Hence, direct measurement of apolipoprotein B (Apo-B), which is present in all atherogenic particles (very-LDL, intermediate-density lipoprotein, and LDL) would be ideal and is a superior indicator of cardiovascular risk. However, current limitations of Apo-B estimation are lack of standardization and lack of technical expertise and cost factor. To overcome these limitations, there is a need to test a particular lipid value from the standard lipid test, which can be used as a surrogate measure of Apo-B. As non-high-density lipoprotein cholesterol (HDL-C) is a measure of the cholesterol content of all Apo-B-containing lipoproteins, it may represent a simple and inexpensive surrogate to Apo-B in select patient subgroups. Hence, this study was undertaken to estimate non-HDL-C and LDL-C from the standard lipid test and also measure Apo-B levels in patients with metabolic syndrome using appropriate statistical methods, correlation and concordance between non-HDL-C versus Apo-B and LDL-C versus Apo-B were analyzed. Methodology: This was a cross-sectional study carried out in Bangalore on 135 patients of metabolic syndrome fulfilling the International Diabetes Federation criteria, from January 2019 to March 2019. Detailed history and examination was undertaken. Fasting blood glucose, Apo-B-100, and lipid profile were obtained in the fasting state venous blood sample. Results: A significant positive correlation was noted between non-HDL-C levels and Apo-B values with a correlation coefficient of 0.883 and area under the curve (AUC) of 0.972. In contrast, the correlation between LDL-C and Apo-B-100 showed a correlation coefficient of 0.815 and AUC of 0.949. Similarly, the concordance/discordance analysis of the same parameters showed concordance across the range of corresponding non-HDL-C and Apo-B quintiles except in the middle quintile where the values were discordant. Concordance was >50% across 80% of the range of values between LDL-C and non-HDL-C. Conclusion: This study showed that there is a good correlation between non-HDL-C levels and Apo-B values with less discordance. Hence, non-HDL-C can be used as a simple and cost-effective alternative (surrogate) to Apo-B estimation.

Signatures of positive selection on the hepatic lipase gene in human populations

The hepatic lipase plays a central role in the lipid metabolism, catalyzing the hydrolysis of phospholipids, monoglycerides, diglycerides, and triglycerides, and acyl-CoA. It is also implied in the conversion of very low-density lipoprotein and intermediate density lipoprotein to low density lipoproteins. As a consequence, the gene encoding the hepatic lipase (LIPC) is associated with several diseases derived from the imbalance of lipids that are in general derived from the interaction between life styles and genetic architecture. Therefore, it is interesting to understand more about the characteristics of the microevolutionary processes affecting genes that, like LIPC, have a role in nutrition and lipid metabolism in human populations. We explored the selection signatures on LIPC in 26 populations, detecting three regions under recent positive selection.

Diabetic dyslipidemia: evaluation and mechanism.

Diabetes is one of the well-established independent risk factors for cardiovascular diseases. Diabetes induces dyslipidemia which is characterized by elevated fasting triglyceride (TG) and reduced high-density lipoprotein-cholesterol (HDL-C), and such diabetic dyslipidemia is a crucial determinant for atherogenesis and atherosclerotic progression in patients with diabetes. Previous measurement methods of lipoproteins have problems including time-consuming (ultracentrifugation) and inaccurate and impossible measurements of TG-rich lipoproteins such as chylomicron, intermediate-density lipoprotein (IDL) and very low-density lipoprotein (VLDL). Our developed anion-exchange high-performance liquid chromatography (AEX-HPLC) can measure all fractions of lipoproteins accurately. Our studies using AEX-HPLC showed that IDL and VLDL in type 2 diabetes were higher than non-diabetic subjects, and IDL and VLDL were higher in the order of type 2 diabetic patients with obesity, type 2 diabetic patients without obesity, and non-diabetic subjects. Here, we also describe the underlying mechanisms for development of diabetic dyslipidemia.

Identification of molecular species of phosphatidylcholine hydroperoxides in native and copper-oxidized triglyceride-rich lipoproteins in humans.

Background Triglyceride-rich lipoproteins are considered to be independent predictors of atherosclerotic cardiovascular disease. The molecular basis of its atherogenicity is uncertain. Here, we aim to identify molecular species of phosphatidylcholine hydroperoxides (PCOOH) in triglyceride-rich lipoproteins. For comparison, copper-oxidized triglyceride-rich lipoproteins were investigated as well. Methods A fasting EDTA blood sample was collected from six healthy human volunteers to isolate two major triglyceride-rich lipoproteins fractions – very low-density lipoproteins (VLDL) and intermediate-density lipoproteins (IDL) using sequential ultracentrifugation. Triglyceride-rich lipoproteins and plasma samples were studied for PCOOH by liquid chromatography (LC) coupled with Orbitrap mass spectrometry. Results Twelve molecular species of PCOOH in triglyceride-rich lipoproteins and/or plasma were identified using the following criteria: (1) high-resolution mass spectrometry (MS) with mass accuracy within 5 ppm, (2) retention time in LC and (3) fragmentation pattern in MS2 and MS3. PC36:4-OOH was most often detected in VLDL, IDL and plasma. The ratio of total PCOOH to phosphatidylcholine progressively increased with the duration of oxidation in both VLDL and IDL. Conclusion This study demonstrated the presence of 12 molecular species of PCOOH in native triglyceride-rich lipoproteins. The frequent detection of PCOOH in triglyceride-rich lipoproteins provides a molecular basis of the atherogenicity of triglyceride-rich lipoproteins. PCOOH in triglyceride-rich lipoproteins might serve as a molecular basis of the atherogenicity of triglyceride-rich lipoproteins.

Innovatively Established Analysis Method for Lipoprotein Profiles Based on High-Performance Anion-Exchange Liquid Chromatography.

Separation analysis of lipoprotein classes have various methods, including ultracentrifugation, electrophoresis, and gel permeation chromatography (GPC). All major lipoprotein classes can be separated via ultracentrifugation, but performing the analysis takes a long time. Low-density lipoprotein (LDL), intermediate-density lipoprotein (IDL), and very low-density lipoprotein (VLDL) in patient samples cannot be sufficiently separated via electrophoresis or GPC. Thus, we established a new method [anion-exchange high-performance liquid chromatography (AEX-HPLC)] by using HPLC with an AEX column containing nonporous gel and an eluent containing chaotropic ions. AEX-HPLC can separate five lipoprotein fractions of high-density lipoprotein (HDL), LDL, IDL, VLDL, and others in human serum, which can be used in substitution for ultracentrifugation method. The method was also approved for clinical use in the public health-care insurance in Japan in 2014. Furthermore, we developed an additional method to measure cholesterol levels of the four leading lipoprotein fractions and two subsequent fractions (i.e., chylomicron and lipoprotein(a)). We evaluated the clinical usefulness of AEX-HPLC in patients with coronary heart disease (CHD), diabetes, and kidney disease and in healthy volunteers. Results indicate that the cholesterol levels in IDL and VLDL measured by AEX-HPLC may be useful risk markers of CHD or diabetes. Furthermore, we developed another new method for the determination of alpha-tocopherol (AT) in lipoprotein classes, and this method is composed of AEX-HPLC for the separation of lipoprotein classes and reverse-phase chromatography to separate AT in each lipoprotein class. The AT levels in LDL were significantly correlated with the lag time to copper ion-induced LDL oxidation, which is an index of oxidation resistance. The application of AEX-HPLC to measure various substances in lipoproteins will be clinically expected in the future.

Metabolic profiling of adolescent non-alcoholic fatty liver disease.

Background: Adolescent non-alcoholic fatty liver disease (NAFLD) is associated with cardiometabolic risk factors. The association between adolescent NAFLD and a wide range of metabolic biomarkers is unclear. We have attempted to determine the differences in metabolic profile of adolescents with and without markers of NAFLD. Methods: We performed cross-sectional analyses in a sample of 3,048 participants from the Avon Longitudinal Study of Parents and Children at age 17. We used three indicators of NAFLD: ALT >40 U/l; AST >40 U/l and ultrasound scan-assessed steatosis. Associations between each measure of NAFLD and 154 metabolic traits, assessed by Nuclear Magnetic Resonance, were analyzed by multivariable linear regression, adjusting for age, sex and BMI. Results: All three indicators of NAFLD were associated with ~0.5 standard deviation (SD) greater concentrations of all extremely large to small very low-density lipoproteins (VLDL) measures. ALT >40U/l was associated with ~0.5SD greater concentrations of very small VLDLs, intermediate-density lipoproteins and low-density lipoproteins. Concentrations of most cholesterols, including remnant cholesterol, all triglycerides and monounsaturated fatty acids, in addition to glycoprotein acetyls (inflammatory marker), were also higher in participants with NAFLD. Conclusions: We have identified differing metabolic profiles between adolescents with and without indicators of NAFLD. These results provide the foundations for future research to determine whether these differences persist and result in adverse future cardiometabolic health.