Lipoprotein Size Research Articles

The relationship between insulin resistance and ion mobility lipoprotein fractions

ObjectiveInsulin resistance (IR) increases risk of type 2 diabetes and atherosclerotic cardiovascular disease and is associated with lipid and lipoprotein abnormalities including high triglycerides (TG) and low high-density lipoprotein cholesterol (HDL-C). Lipoprotein size and lipoprotein subfractions (LS) have also been used to assist in identifying persons with IR. Associations of LS and IR have not been validated using both direct measures of IR and direct measures of LS. We assessed the usefulness of fasting lipoprotein subfractions (LS) by ion mobility to identify individuals with IR. MethodsLipid panel, LS by ion mobility (LS-IM), and IR by steady-state plasma glucose (SSPG) concentration were assessed in 526 adult volunteers without diabetes. IR was defined as being in the highest tertile of SSPG concentration. LS-IM score was calculated by linear combination of regression coefficients from a stepwise regression analysis with SSPG concentration as the dependent variable. Improvement in prediction of IR was evaluated after combining LS-IM score with TG/HDL-C, TG/HDL-C and BMI as well as with TG/HDL-C, BMI, sex, race and ethnicity. IR prediction was evaluated by area under the receiver operating characteristic curve (AUC) and positive predictive value (PPV) considering the highest 5% of scores as positive test. ResultsPrediction of IR was similar by LS-IM score and TG/HDL-C (AUC=0.68; PPV=0.59 and AUC=0.70; PPV=0.59, respectively) and prediction was improved when LS-IM was combined with TG/HDL-C (AUC=0.73; PPV=0.70), TG/HDL-C and BMI (AUC=0.82; PPV=0.81) and with TG/HDL-C, BMI, sex, race and ethnicity (AUC=0.84; PPV=0.89). ConclusionFor identifying individuals with IR, LS-IM score and TG/HDL-C are comparable and their combination further improves IR prediction by TG/HDL-C alone. Among patients who have undergone IM testing, the LS-IM score may assist prioritization of subjects for further evaluation and interventions to reduce IR.

Association of physical activity with metabolic profile from adolescence to adulthood.

Physical activity benefits cardiometabolic health, but little is known about its detailed links with serum lipoproteins, amino acids, and glucose metabolism at young age. We therefore studied the association of physical activity with a comprehensive metabolic profile measured repeatedly in adolescence. The cohort is derived from the longitudinal Special Turku Coronary Risk Factor Intervention Project. At ages 13, 15, 17, and 19 years, data on physical activity were collected by a questionnaire, and circulating metabolic measures were quantified by nuclear magnetic resonance metabolomics from repeatedly assessed serum samples (age 13: n=503, 15: n=472, 17: n=466, and 19: n=361). Leisure-time physical activity (LTPA;MET h/wk) was directly associated with concentrations of polyunsaturated fatty acids, and inversely with the ratio of monounsaturated fatty acids to total fatty acids (-0.006SD; [-0.008, -0.003]; p < 0.0001). LTPA was inversely associated with very-low-density lipoprotein (VLDL) particle concentration (-0.003SD; [-0.005, -0.001]; p=0.002) and VLDL particle size (-0.005SD; [-0.007, -0.003]; p < 0.0001). LTPA showed direct association with the particle concentration and size of high-density lipoprotein (HDL), and HDL cholesterol concentration (0.004SD; [0.002, 0.006]; p < 0.0001). Inverse associations of LTPA with triglyceride and total lipid concentrations in large to small sized VLDL subclasses were found. Weaker associations were seen for other metabolic measures including inverse associations with concentrations of lactate, isoleucine, glycoprotein acetylation, and a direct association with creatinine concentration. The results remained after adjusting for body mass index and proportions of energy intakes from macronutrients. Physical activity during adolescence is beneficially associated with the metabolic profile including novel markers. The results support recommendations on physical activity during adolescence to promote health and possibly reduce future disease risks.

Early metabolomic, lipid and lipoprotein changes in response to medical and surgical therapeutic approaches to obesity

BackgroundGlucagon-like peptide-1 receptor agonists (GLP-1RA) and bariatric surgery have proven to be effective treatments for obesity and cardiometabolic conditions. We aimed to explore the early metabolomic changes in response to GLP-1RA (liraglutide) therapy vs. placebo and in comparison to bariatric surgery. MethodsThree clinical studies were conducted: a bariatric surgery cohort study of participants with morbid obesity who underwent either Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) studied over four and twelve weeks, and two randomized placebo-controlled, crossover double blind studies of liraglutide vs. placebo administration in participants with type 2 diabetes (T2D) and participants with obesity studied for three and five weeks, respectively. Nuclear magnetic resonance spectroscopy-derived metabolomic data were assessed in all eligible participants who completed all the scheduled in-clinic visits. The primary outcome of the study was to explore the changes of the metabolome among participants with obesity with and without T2D receiving the GLP-1RA liraglutide vs. placebo and participants with obesity undergoing bariatric surgery during the three to five-week study period. In addition, we assessed the bariatric surgery effects longitudinally over the twelve weeks of the study and the differences between the bariatric surgery subgroups on the metabolome. The trials are registered with ClinicalTrials.gov, numbers NCT03851874, NCT01562678 and NCT02944500. ResultsBariatric surgery had a more pronounced effect on weight and body mass index reduction (−14.19 ± 5.27 kg and − 5.19 ± 5.27, respectively, p < 0.001 for both) and resulted in more pronounced metabolomic and lipidomic changes compared to liraglutide therapy at four weeks postoperatively. Significant changes were observed in lipoprotein parameters, inflammatory markers, ketone bodies, citrate, and branched-chain amino acids after the first three to five weeks of intervention. After adjusting for the amount of weight loss, a significant difference among the study groups remained only for acetoacetate, β-hydroxybutyrate, and citrate (p < 0.05 after FDR correction). Glucose levels were significantly reduced in all intervention groups but mainly in the T2D group receiving GLP-1RA treatment. After adjusting for weight loss, only glucose levels remained significant (p = 0.001 after FDR correction), mainly due to the glucose change in the T2D group receiving GLP-1RA. Similar results with those observed at four weeks were observed in the surgical group when delta changes at twelve weeks were assessed. Comparing the two types of bariatric surgery, an intervention effect was more pronounced in the RYGB subgroup regarding total triglycerides, triglyceride-rich lipoprotein size, and trimethylamine-N-oxide (p for intervention: 0.031, 0.028, 0.036, respectively). However, after applying FDR correction, these changes deemed to be only suggestive; only time effects remained significant with no significant changes persisting in relation to the types of bariatric surgery. ConclusionsThe results of this study suggest that the early metabolomic, lipid and lipoprotein changes observed between liraglutide treatment and bariatric surgery are similar and result largely from the changes in patients' body weight. Specific changes observed in the short-term post-surgical period between bariatric vs. nonsurgical treated participants, i.e., acetoacetate, β-hydroxybutyrate, and citrate changes, may reflect changes in patient diets and calorie intake indicating potential calorie and diet-driven metabolomics/lipidomic effects in the short-term postoperatively. Significant differences observed between SG and RYGB need to be confirmed and extended by future studies.

Effects of Gestational Diabetes Mellitus on Cholesterol Metabolism in Women with High-Risk Pregnancies: Possible Implications for Neonatal Outcome.

Metabolic disorders in pregnancy, particularly gestational diabetes mellitus (GDM), are associated with an increased risk for adverse pregnancy outcome and long-term cardiometabolic health of mother and child. This study analyzed changes of serum cholesterol synthesis and absorption markers during the course of high-risk pregnancies, with respect to the development of GDM. Possible associations of maternal lipid biomarkers with neonatal characteristics were also investigated. The study included 63 women with high risk for development of pregnancy complications. Size and proportions of small low-density (LDL) and high-density lipoprotein (HDL) particles were assessed across trimesters (T1–T3), as well as concentrations of cholesterol synthesis (lathosterol, desmosterol) and absorption markers (campesterol, β-sitosterol). During the study, 15 women developed GDM, while 48 had no complications (non-GDM). As compared to the non-GDM group, women with GDM had significantly higher triglycerides in each trimester, while having a lower HDL-C level in T3. In addition, they had significantly lower levels of β-sitosterol in T3 (p < 0.05). Cholesterol synthesis markers increased across trimesters in both groups. A decrease in serum β-sitosterol levels during the course of pregnancies affected by GDM was observed. The prevalence of small-sized HDL decreased in non-GDM, while in the GDM group remained unchanged across trimesters. Newborn’s size in the non-GDM group was significantly higher (p < 0.01) and inversely associated with proportions of both small, dense LDL and HDL particles (p < 0.05) in maternal plasma in T1. In conclusion, high-risk pregnancies affected by GDM are characterized by altered cholesterol absorption and HDL maturation. Advanced lipid testing may indicate disturbed lipid homeostasis in GDM.

The relative importance of particle count, type, and size of ApoB-containing lipoproteins in risk of myocardial infarction

Abstract Background An accumulating body of evidence suggests that the number of apolipoprotein B-containing particles (ApoB-P) is more predictive of cardiovascular risk than their lipid content. However, it is unclear if this association is consistent across different lipoprotein types and sizes. Purpose We aimed to evaluate if particle type and size are associated with incident myocardial infarction (MI) beyond ApoB-P count. Moreover, we aimed to determine if the risk associated with lipoprotein(a) is additive to that of ApoB-P. Methods This prospective cohort study included 96,126 participants without prior history of stroke, coronary or peripheral artery disease or use of lipid-lowering medication from the UK Biobank. Count and size of VLDL, IDL, LDL, and HDL, as well as ApoB level and total ApoB-P count were measured in non-fasting plasma samples by nuclear magnetic resonance platform. Lipoprotein(a) was measured by immunoturbidimetric assay. We explored associations between these lipoprotein markers and incident MI using Cox proportional hazard models adjusted sequentially for clinical covariates, HDL count and size, and ApoB-P. Results Over a median follow-up of 12.1 years, 1702 participants had incident MI. In unadjusted models, 1-SD increases in ApoB-P count, ratio of VLDL to (LDL+IDL) particle counts, VLDL size and lipoprotein(a) were associated with a higher risk of MI, while LDL size was associated with a lower risk of MI (Table 1). When adjusting for clinical covariates and lipid parameters, only ApoB-P and lipoprotein(a) remained significantly associated with a higher risk of MI (HR: 1.40 [1.32; 1.48] and 1.20 [1.14; 1.27], respectively). Adjusted restricted cubic splines confirmed findings from linear trend Cox models (Figure 1). ApoB-P count was highly correlated with ApoB level (r=0.99), and replication of analyses replacing one for another revealed no change in results. Conclusion The risk of MI is independently associated with the total particle count of all ApoB-P, and not the size or type of these lipoproteins. ApoB level can be used as a very accurate surrogate of ApoB-P count in the clinical setting. Lipoprotein(a) is associated with MI risk independently of total particle count, and therefore, the combination of ApoB and lipoprotein(a) may provide the optimal clinical evaluation of lipid-mediated MI risk. Funding Acknowledgement Type of funding sources: None.

Lycopene-rich diets modulate HDL functionality and associated inflammatory markers without affecting lipoprotein size and distribution in moderately overweight, disease-free, middle-aged adults: A randomized controlled trial.

BackgroundThe consumption of lycopene-rich foods may lower cardiovascular disease (CVD) risk. Lycopene circulates in the blood bound to lipoproteins, including high-density lipoproteins (HDLs). Preliminary data from our group showed that increased consumption of tomato-based food or lycopene supplement in middle-aged subjects led to functional changes to HDL's sub-fractions, HDL2 and HDL3. These changes were also associated with a decrease in serum amyloid A (SAA), potentially enhancing their anti-atherogenic properties.ObjectiveWe carried out a comprehensive randomized controlled intervention trial with healthy middle-aged volunteers to assess whether the consumption of tomato-based foods or lycopene supplements affects HDL functionality and associated inflammatory markers, and lipoprotein subfractions size and distribution.DesignVolunteers (225, aged 40–65 years) were randomly assigned to one of three dietary intervention groups and asked to consume a control diet (low in tomato-based foods, <10 mg lycopene/week), a lycopene-rich diet (224–350 mg lycopene/week), or the control diet with a lycopene supplement (70 mg lycopene/week). HDL2 and HDL3 were isolated by ultracentrifugation. Compliance was monitored by assessing lycopene concentration in serum. Systemic and HDL-associated inflammation was assessed by measuring SAA concentrations. HDL functionality was determined by monitoring paraoxonase-1 (PON-1), cholesteryl ester transfer protein (CETP), and lecithin cholesterol acyltransferase (LCAT) activities. The lipoprotein subfractions profile was assessed by NMR.ResultsLycopene in serum and HDL significantly increased following consumption of both the high tomato diet and lycopene supplement (p ≤ 0.001 for both). Lycopene, either as a tomato-rich food or a supplement, enhanced both serum- and HDL3-PON-1 activities (p ≤ 0.001 and p = 0.036, respectively), while significantly reducing HDL3-SAA-related inflammation (p = 0.001). Lycopene supplement also significantly increased HDL3-LCAT activity (p = 0.05), and reduced the activity of both HDL2- and HDL3-CETP (p = 0.005 and p = 0.002, respectively). These changes were not associated with changes in the subclasses distribution for all lipoprotein fractions or the size of lipoprotein subclasses.ConclusionOur results showed that dietary lycopene can significantly enhance HDL functionality, without associated changes in particle size and distribution, by modulating the activity of HDL-associated enzymes. Concomitantly, dietary lycopene significantly decreased serum- and HDL3-associated SAA, confirming that SAA may represent a sensitive inflammatory biomarker to dietary change.Clinical Trial Register(https://www.isrctn.com), ISRCTN34203810.

Identification of different lipoprotein response types in people following a Mediterranean diet pattern with and without whole eggs

A Mediterranean (MED) diet decreases atherogenic lipoproteins and cardiovascular disease risk. We tested the hypothesis that daily consumption of whole eggs in a MED diet improves lipid metabolism compared with responses of both a control American diet and a MED diet without whole eggs. Thirty-nine overweight to obese participants were recruited into a randomized, crossover designed, controlled feeding trial evaluating 3 diets: a control, average American diet (AAD), a MED diet without whole eggs (MED-E), and a MED diet plus whole fresh eggs (1 whole egg/1000 kcal; MED+E). Treatments lasted 4 weeks followed by a >4-week washout period. Lipid concentrations, lipoprotein particle size, and number were determined at baseline and posttreatment. Intake of the AAD and MED-E decreased total cholesterol and low-density lipoprotein (LDL) concentrations (change from baseline, P < .05), without a treatment effect. Similarly, MED-E reduced (change from baseline, P < .05) triglyceride concentrations, without a treatment effect. Particle concentrations were reduced for intermediate-density lipoprotein (IDL; 26%, P < .05) and total LDL (8%, P < .05) by MED-E intake only. Very low-density lipoprotein size was reduced by MED-E intake (treatment effect, P = .04). Variability in responses, assessed by unsupervised machine learning, identified 3 main clusters of IDL- and LDL-type responses. Adoption of a MED diet meal plan without whole eggs improved lipid parameters associated with reduced cardiovascular disease risk. Significant treatment differences following inclusion of whole eggs were not observed. Individual differences in lipoprotein responses warrants further exploration.

Effect of olezarsen targeting APOC-III on lipoprotein size and particle number measured by NMR in patients with hypertriglyceridemia

Olezarsen is a hepatocyte-targeted, GalNAc-modified antisense oligonucleotide that decreases plasma levels of apolipoprotein C-III (apoC-III) and triglyceride-rich lipoproteins (TRLs). To define the effect of olezarsen on NMR-derived lipoprotein particle size and concentration. Patients (n=114) with or at risk for atherosclerotic cardiovascular disease and fasting triglycerides ≥200 and <500 mg/dL received olezarsen (10 or 50 mg every 4 weeks, 15 mg every 2 weeks, or 10 mg every week) or saline placebo subcutaneously for 6-12 months. NMR LipoProfile® analysis was performed in frozen EDTA plasma samples collected at baseline and at the primary analysis timepoint (PAT) at 6 months. A dose-dependent relationship was generally noted with increasing cumulative doses of olezarsen in TRL particle (TRLP), LDL particle (LDL-P) and HDL (HDL-P) particle concentrations. In the 50 mg every 4 weeks dose, compared to placebo, olezarsen resulted in a significant reduction in total TRL-P (51%, P<0.0001) with largest reductions in large-size (68%, P<0.0001) and medium-size (63%, P<0.0001) TRL-P. Total LDL-P concentration was not changed, but large LDL-P increased by 186% (p=0.0034), and small LDL-P decreased by 39% (p=0.0713). Total HDL-P concentration increased by 15% (P=0.0006), driven primarily by a 32% increase in small HDL subspecies (diameters <8.3 nm) (P=0.0008). Olezarsen results in favorable changes in lipoprotein concentration and particle size, primarily manifested by reduction in TRLs, remodeling to larger LDL particles, and increase in small HDL-P. These findings suggest that apoC-III inhibition improves the overall atherogenic risk profile.

The Association of Lipids and Lipoproteins with Hip Fracture Risk: The Cardiovascular Health Study

BackgroundIt is uncertain if lipids or lipoproteins are associated with osteoporotic fractures. In this study, incident hip fracture risk according to conventional lipid levels and lipoprotein levels and sizes was examined. MethodsWe followed 5832 participants aged ≥65 years from the Cardiovascular Health Study for hip fracture for a mean of 13.5 (SD 5.7) years. Standard enzymatic methods were used to determine lipid levels (ie, high-density lipoprotein-cholesterol [HDL-c], low-density lipoprotein-cholesterol [LDL-c], and triglycerides). Nuclear magnetic resonance spectroscopy was used to measure lipoprotein fractions (ie, very-low-density lipoprotein-particle [VLDL-P], low-density lipoprotein-particle [LDL-P], high-density lipoprotein-particle [HDL-P]) in a subset of 1849 participants. ResultsWe documented 755 incident hip fractures among women (1.19 fractures per 100 participant years [95% confidence interval, 1.04, 1.35]) and 197 among men (0.67 fractures per 100 participant years [95% CI, 0.41, 1.10]) over an average follow-up. HDL-c and LDL-c levels had statistically significant nonlinear U-shaped relationships with hip fracture risk (HDL-c, P = .009; LDL-c, P = .02). Triglyceride levels were not significantly associated with hip fracture risk. In fully adjusted conjoint models, higher VLDL-P concentration (hazard ratio [HR] per 1 standard deviation [SD] increment 1.47 [1.13, 1.91] and size [HR per 1 SD increment 1.24 [1.05, 1.46]) and higher high-density lipoprotein particle size (HR per 1 SD increment 1.81 [1.25, 2.62]) were all associated with higher hip fracture risk. ConclusionsLipids and lipoproteins are associated with hip fracture risk in older adults. The associations are complex. Mechanistic studies are needed to understand these findings.

Postprandial and Fasting Metabolic Signatures: Insights From the ZOE PREDICT 1 Study

ObjectivesPostprandial metabolomic signatures, although not well characterized, may provide greater insight into individuals’ responses to food and subsequent cardiometabolic disease risk compared to fasting and routine clinical measures. Using the PREDICT 1 cohort, we assessed postprandial changes and inter-individual variability in metabolites sequenced by NMR. MethodsThe ZOE PREDICT 1 study (n = 1,002 healthy UK adults; NCT03479866) measured 250 metabolite parameters (Nightingale Health NMR panel, related to lipids, amino acids, glycolysis, ketones, and glycoprotein acetyls (GlycA)) by venous cannulation at fasting and postprandially after a mixed nutrient sequential test meal (4 and 6 h after meal 1, 3.7 MJ; meal 2 given at 4 h, 2.2 MJ). Postprandial changes in metabolites and their inter-individual variability (median absolute difference from the median (MADM)/median (%)) were evaluated. Associations (Spearman’s correlations) and differences in variances (Fligner-Killeen test) were assessed between fasting and postprandial (6 h) measures. ResultsA significant 6 h postprandial change from fasting was seen in 85% of metabolites; of which, 47% increased, and 53% decreased (Kruskal-Wallis p < 0.05 for all). Ketone bodies and very-large lipoprotein particles showed the greatest changes. Fasting and postprandial measures had large, yet similar, inter-individual variability (MADM/median; 15% at 0, 4 and 6 h (mean for all)) and were strongly correlated (r > 0.8; 71% of measures), although ketone bodies, glucose, branched chain amino acids and LDL diameter were only weakly correlated (r < 0.5). Inter-individual patterns of response differed postprandially compared to fasting (Fligner-Killeen test of variance, p < 0.05). ConclusionsIn this large and generally healthy cohort, we demonstrate significant changes in circulating metabolites between the fasting and postprandial phase, as expected, within lipoprotein size and composition remodelling, glycolysis, essential amino acid and ketone body pathways. The large inter-individual variability in postprandial metabolite levels, suggests dietary challenges offer an opportunity for stratifying metabolic responses. Funding SourcesZOE Ltd.

Is There a Correlation between Dietary and Blood Cholesterol? Evidence from Epidemiological Data and Clinical Interventions.

Dietary cholesterol has been a topic of debate since the 1960s when the first dietary guidelines that limited cholesterol intake to no more than 300 mg/day were set. These recommendations were followed for several years, and it was not until the late 1990s when they were finally challenged by the newer information derived from epidemiological studies and meta-analysis, which confirmed the lack of correlation between dietary and blood cholesterol. Further, dietary interventions in which challenges of cholesterol intake were evaluated in diverse populations not only confirmed these findings but also reported beneficial effects on plasma lipoprotein subfractions and size as well as increases in HDL cholesterol and in the functionality of HDL. In this review, we evaluate the evidence from recent epidemiological analysis and meta-analysis as well as clinical trials to have a better understanding of the lack of correlation between dietary and blood cholesterol.

Small Dense LDL: Scientific Background, Clinical Relevance, and Recent Evidence Still a Risk Even with 'Normal' LDL-C Levels.

Residual cardiovascular disease event risk, following statin use and low-density lipoprotein cholesterol (LDL-C) reduction, remains an important and common medical conundrum. Identifying patients with significant residual risk, despite statin drug use, is an unmet clinical need. One pathophysiologic disorder that contributes to residual risk is abnormal distribution in lipoprotein size and density, which is referred to as lipoprotein heterogeneity. Differences in low density lipoprotein (LDL) composition and size have been linked to coronary heart disease (CHD) risk and arteriographic disease progression. The clinical relevance has been investigated in numerous trials since the 1950s. Despite this long history, controversy remains regarding the clinical utility of LDL heterogeneity measurement. Recent clinical trial evidence reinforces the relevance of LDL heterogeneity measurement and the impact on CHD risk prediction and outcomes. The determination of LDL subclass distribution improves CHD risk prediction and guides appropriate treatment.

Comparison of the modified polyacrylamide gradient gel electrophoresis and high-performance liquid chromatography methods in determining LDL size

Abstract Objectives In this study, we aimed to compare modified Krauss polyacrylamide gradient gel electrophoresis (PAGGE) and high-performance liquid chromatography (HPLC) methods in classification, quantification, and separation of lipoproteins and determining low-density lipoprotein (LDL) size. Methods Blood specimens were obtained from eighty-seven volunteers. We measured LDL size using the PAGGE method and HPLC method with total cholesterol (TC) and triglyceride (TG) peaks. In the PAGGE method, Coomassie Brilliant Blue (CBB) staining was used instead of Sudan black staining, unlike the original method. The relationship between PAGGE and HPLC methods was evaluated by Pearson correlation test and Passing-Bablok regression analysis. Agreement between them was evaluated by Kappa analysis and Bland-Altman plots. Results Statistically significant correlation was found between the LDL size with PAGGE and HPLC methods under the cholesterol curve (HPLC-TC) (r=0.924, p&lt;0.001). Similarly, there was a statistically significant correlation between PAGGE and HPLC methods under the TG curve (HPLC-TG) (r=0.910, p&lt;0.001). In the PAGGE method, within-day precision was found as 2% and between-day precision as 3%. It was determined agreement between HPLC-TC vs. HPLC-TG methods and HPLC-TG vs. PAGGE methods was higher than HPLC-TC vs. PAGGE (Kappa values; 0.68, 0.71, and 0.44, respectively). Conclusions The PAGGE method can be a reliable method for measuring LDL size. HPLC method under cholesterol and triglyceride peaks may be used in clinical practice interchangeably, but clinical decision limits should be different. In addition, our study demonstrated that measurement methods for LDL size could be simplified with several modifications.

Circulating Metabolome and White Matter Hyperintensities in Women and Men.

White matter hyperintensities (WMH), identified on T2-weighted magnetic resonance images of the human brain as areas of enhanced brightness, are a major risk factor of stroke, dementia, and death. There are no large-scale studies testing associations between WMH and circulating metabolites. We studied up to 9290 individuals (50.7% female, average age 61 years) from 15 populations of 8 community-based cohorts. WMH volume was quantified from T2-weighted or fluid-attenuated inversion recovery images or as hypointensities on T1-weighted images. Circulating metabolomic measures were assessed with mass spectrometry and nuclear magnetic resonance spectroscopy. Associations between WMH and metabolomic measures were tested by fitting linear regression models in the pooled sample and in sex-stratified and statin treatment-stratified subsamples. Our basic models were adjusted for age, sex, age×sex, and technical covariates, and our fully adjusted models were also adjusted for statin treatment, hypertension, type 2 diabetes, smoking, body mass index, and estimated glomerular filtration rate. Population-specific results were meta-analyzed using the fixed-effect inverse variance-weighted method. Associations with false discovery rate (FDR)-adjusted P values (PFDR)<0.05 were considered significant. In the meta-analysis of results from the basic models, we identified 30 metabolomic measures associated with WMH (PFDR<0.05), 7 of which remained significant in the fully adjusted models. The most significant association was with higher level of hydroxyphenylpyruvate in men (PFDR.full.adj=1.40×10-7) and in both the pooled sample (PFDR.full.adj=1.66×10-4) and statin-untreated (PFDR.full.adj=1.65×10-6) subsample. In men, hydroxyphenylpyruvate explained 3% to 14% of variance in WMH. In men and the pooled sample, WMH were also associated with lower levels of lysophosphatidylcholines and hydroxysphingomyelins and a larger diameter of low-density lipoprotein particles, likely arising from higher triglyceride to total lipids and lower cholesteryl ester to total lipids ratios within these particles. In women, the only significant association was with higher level of glucuronate (PFDR=0.047). Circulating metabolomic measures, including multiple lipid measures (eg, lysophosphatidylcholines, hydroxysphingomyelins, low-density lipoprotein size and composition) and nonlipid metabolites (eg, hydroxyphenylpyruvate, glucuronate), associate with WMH in a general population of middle-aged and older adults. Some metabolomic measures show marked sex specificities and explain a sizable proportion of WMH variance.

Uticaj metaboličkih parametara na veličinu i subklasu LDL i HDL kod adolescenata sa dijabetesom tip 1

Alterations in the serum of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) size and subclass contribute to the atherogenesis in coronary artery disease in diabetic patients. The purpose of this study is to evaluate the effect of metabolic parameters on LDL and HDL size and subclasses in adolescents with type 1 diabetes. The cross-sectional study included 43 adolescents (23 females, 20 males) with type 1 diabetes of mean age 15.09±1.94 years, with mean disease duration of 5.86 ± 3.08 years. LDL and HDL particles were separated by polyacrylamide gradient gel electrophoresis, while serum lipid parameters were determined by routine laboratory methods. Patients with inadequate metabolic control (HbA1c ≥ 7.5%) had a higher mean value of triglycerides (TG) (p = 0.041), higher proportions of small, dense LDL particles (p = 0.045), higher proportions of LDL IIA subclasses (p=0.03) and smaller LDL diameter (p = 0.02) and HDL diameter (p = 0.04) than patients with optimal metabolic control (HbA1c &lt; 7.5%). Higher HbA1c and higher TG levels were statistically significantly related to small, dense LDL (r=0.341, p=0.025; r= 0.394, p= 0.009) and HDL particles (r=0.684, p=0.000; r=0.421, p=0.005). Predictors of small, dense LDL and HDL particles, which contribute to atherogenesis, were high HbA1c (HR = 1.52, 95% CI: 0.97-2.40; HR 3.87, 95% CI: 2.11-7.10) and elevated TG (HR= 1.10, 95% CI: 1.00-1.20; HR 1.85, 95% CI: 1.07-3.21). Diabetic adolescents require particular attention in order to minimize factors such as high HbA1c and elevated TGs in the development of future cardiovascular events.

Bmal1 regulates production of larger lipoproteins by modulating cAMP-responsive element-binding protein H and apolipoprotein AIV.

High plasma lipid/lipoprotein levels are risk factors for various metabolic diseases. We previously showed that circadian rhythms regulate plasma lipids and deregulation of these rhythms causes hyperlipidemia and atherosclerosis in mice. Here, we show that global and liver-specific brain and muscle aryl hydrocarbon receptor nuclear translocator-like 1 (Bmal1)-deficient mice maintained on a chow or Western diet developed hyperlipidemia, denoted by the presence of higher amounts of triglyceride-rich and apolipoprotein AIV (ApoAIV)-rich larger chylomicron and VLDL due to overproduction. Bmal1 deficiency decreased small heterodimer partner (Shp) and increased microsomal triglyceride transfer protein (MTP), a key protein that facilitates primordial lipoprotein assembly and secretion. Moreover, we show that Bmal1 regulates cAMP-responsive element-binding protein H (Crebh) to modulate ApoAIV expression and the assembly of larger lipoproteins. This is supported by the observation that Crebh-deficient and ApoAIV-deficient mice, along with Bmal1-deficient mice with knockdown of Crebh, had smaller lipoproteins. Further, overexpression of Bmal1 in Crebh-deficient mice had no effect on ApoAIV expression and lipoprotein size. These studies indicate that regulation of ApoAIV and assembly of larger lipoproteins by Bmal1 requires Crebh. Mechanistic studies showed that Bmal1 regulates Crebh expression by two mechanisms. First, Bmal1 interacts with the Crebh promoter to control circadian regulation. Second, Bmal1 increases Rev-erbα expression, and nuclear receptor subfamily 1 group D member 1 (Nr1D1, Rev-erbα) interacts with the Crebh promoter to repress expression. In short, Bmal1 modulates both the synthesis of primordial lipoproteins and their subsequent expansion into larger lipoproteins by regulating two different proteins, MTP and ApoAIV, through two different transcription factors, Shp and Crebh. It is likely that disruptions in circadian mechanisms contribute to hyperlipidemia and that avoiding disruptions in circadian rhythms may limit/prevent hyperlipidemia and atherosclerosis.

Effect of renal function on high-density lipoprotein particles in patients with coronary heart disease

BackgroundAlthough renal insufficiency and dyslipidemia are known to be closely associated, the effect of kidney function on the size and clinical value of high-density lipoprotein (HDL) particles remains largely unknown, especially in patients with coronary heart disease.MethodsA total of 419 coronary heart disease patients and 105 non-coronary heart disease patients were included. HDL particle size, represented by HDL-C/apoA-I, was compared between groups stratified by estimated glomerular filtration rate (eGFR) and Gensini scores using standard Student’s t test and one-way ANOVA. Pearson’s correlation test was performed to analyze the association between eGFR and HDL-C/apoA-I in patients with coronary heart disease. The relationship between HDL particle size and the occurrence of coronary heart disease was explored using Univariate logistic regression analysis.ResultsIn patients with coronary heart disease, between-group analysis revealed that HDL-C/apoA-I increased as eGFR declined, and significance appeared as eGFR declined to under 60 ml/min·1.73 m2 (P < 0.001), and Pearson's correlation test also confirmed an inverse correlation between eGFR and HDL-C/apoA-I levels in coronary heart disease patients. When stratified by Gensini scores, in coronary heart disease patients with eGFR ≥ 90 mL/(min·1.73 m2), those with higher Gensini scores had smaller HDL-C/apoA-I. However, with or without kidney insufficiency, smaller HDL-C/apoA-I was associated with a higher occurrence of coronary heart disease (P < 0.05).ConclusionWith the presence of renal insufficiency, HDL-C/apoA1 was higher in patients with coronary heart disease. Lower HDL-C/apoA1 was still associated with a higher occurrence of coronary heart disease, but the original association between lower HDL-C/apoA1 and more severe coronary artery stenosis was lost in patients with renal insufficiency.

Lipoprotein size is a main determinant for the rate of hydrolysis by exogenous LPL in human plasma

LPL is a key player in plasma triglyceride metabolism. Consequently, LPL is regulated by several proteins during synthesis, folding, secretion, and transport to its site of action at the luminal side of capillaries, as well as during the catalytic reaction. Some proteins are well known, whereas others have been identified but are still not fully understood. We set out to study the effects of the natural variations in the plasma levels of all known LPL regulators on the activity of purified LPL added to samples of fasted plasma taken from 117 individuals. The enzymatic activity was measured at 25°C using isothermal titration calorimetry. This method allows quantification of the ability of an added fixed amount of exogenous LPL to hydrolyze triglyceride-rich lipoproteins in plasma samples by measuring the heat produced. Our results indicate that, under the conditions used, the normal variation in the endogenous levels of apolipoprotein C1, C2, and C3 or the levels of angiopoietin-like proteins 3, 4, and 8 in the fasted plasma samples had no significant effect on the recorded activity of the added LPL. Instead, the key determinant for the LPL activity was a lipid signature strongly correlated to the average size of the VLDL particles. The signature involved not only several lipoprotein and plasma lipid parameters but also apolipoprotein A5 levels. While the measurements cannot fully represent the action of LPL when attached to the capillary wall, our study provides knowledge on the interindividual variation of LPL lipolysis rates in human plasma.

Hibernating brown bears are protected against atherogenic dyslipidemia

To investigate mechanisms by which hibernators avoid atherogenic hyperlipidemia during hibernation, we assessed lipoprotein and cholesterol metabolisms of free-ranging Scandinavian brown bears (Ursus arctos). In winter- and summer-captured bears, we measured lipoprotein sizes and sub-classes, triglyceride-related plasma-enzyme activities, and muscle lipid composition along with plasma-levels of antioxidant capacities and inflammatory markers. Although hibernating bears increased nearly all lipid levels, a 36%-higher cholesteryl-ester transfer-protein activity allowed to stabilize lipid composition of high-density lipoproteins (HDL). Levels of inflammatory metabolites, i.e., 7-ketocholesterol and 11ß-prostaglandin F2α, declined in winter and correlated inversely with cardioprotective HDL2b-proportions and HDL-sizes that increased during hibernation. Lower muscle-cholesterol concentrations and lecithin-cholesterol acyltransferase activity in winter suggest that hibernating bears tightly controlled peripheral-cholesterol synthesis and/or release. Finally, greater plasma-antioxidant capacities prevented excessive lipid-specific oxidative damages in plasma and muscles of hibernating bears. Hence, the brown bear manages large lipid fluxes during hibernation, without developing adverse atherogenic effects that occur in humans and non-hibernators.

Effects of SNVs in ABCA1, ABCG1, ABCG5, ABCG8, and SCARB1 Genes on Plasma Lipids, Lipoproteins, and Adiposity Markers in a Brazilian Population.

Several proteins are involved in cholesterol homeostasis, as scavenger receptor class B type I and ATP-binding cassette (ABC) transporters including ABCA1, ABCG1, ABCG5, and ABCG8. This study aimed to determine the effects of single nucleotide variants (SNVs) rs2275543 (ABCA1), rs1893590 (ABCG1), rs6720173 (ABCG5), rs6544718 (ABCG8), and rs5888 (SCARB1) on plasma lipids, lipoproteins, and adiposity markers in an asymptomatic population and its sex-specific effects. Volunteers (n = 590) were selected and plasma lipids, lipoproteins, and adiposity markers (waist-to-hip and waist-to-height ratios, lipid accumulation product and body adiposity index) were measured. Genomic DNA was isolated from peripheral blood cells according to the method adapted from Gross-Bellard. SNVs were detected in the TaqMan® OpenArray® Real-Time polymerase chain reaction platform and data analyses were performed using the TaqMan® Genotyper Software. The rs2275543*C point to an increase of high-density lipoprotein size in females while in males very-low-density lipoprotein, cholesterol, and triglycerides were statistically lower (P value < 0.05). The rs1893590*C was statistically associated with lower apolipoprotein A-I levels and higher activities of paraoxonase-1 and cholesteryl ester transfer protein (P value < 0.05). The rs6720173 was statistically associated with an increase in cholesterol and low-density lipoprotein cholesterol in males; moreover, rs6544718*T reduced adiposity markers in females (P value < 0.05). Regarding the rs5888, a decreased adiposity marker in the total population and in females occurred (P value < 0.05). Multivariate analysis of variance showed that SNVs could influence components of high-density lipoprotein metabolism, mainly through ABCG1 (P value < 0.05). The ABCA1 and ABCG5 variants showed sex-specific effects on lipids and lipoproteins, while SCARB1 and ABCG8 variants might influence adiposity markers in females. Our data indicate a possible role of ABCG1 on HDL metabolism.