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Background We examined the interplay of apolipoprotein B (apoB) and LDL particle size, approximated by the LDL-cholesterol (LDL-C)/apoB ratio, on the risk of new-onset coronary heart disease (CHD). Methods Participants without cardiovascular disease from the UK Biobank (UKB; n = 308 182), the Women’s Health Study (WHS; n = 26 204), and the Framingham Heart Study (FHS; n = 2839) were included. Multivariable Cox models were used to assess the relationship between apoB and LDL-C/apoB ratio and incidence of CHD (14 994 events). Our analyses were adjusted for age, sex (except WHS), HDL-cholesterol (HDL-C), systolic blood pressure, antihypertensive treatment, diabetes, and smoking. Results In all 3 studies, there was a strong positive correlation between apoB and LDL-C (correlation coefficients r = 0.80 or higher) and a weak inverse correlation of apoB with LDL-C/apoB ratio (−0.28 ≤ r ≤ −0.14). For all 3 cohorts, CHD risk was higher for higher levels of apoB. Upon multivariable adjustment, the association between apoB and new-onset CHD remained robust and statistically significant in all 3 cohorts with hazard ratios per 1 SD (95% CI): 1.24 (1.22–1.27), 1.33 (1.20–1.47), and 1.24 (1.09–1.42) for UKB, WHS, and FHS, respectively. However, the association between LDL-C/apoB and CHD was statistically significant only in the FHS cohort: 0.78 (0.64–0.94). Conclusions Our analysis confirms that apoB is a strong risk factor for CHD. However, given the null association in 2 of the 3 studies, we cannot confirm that cholesterol-depleted LDL particles are substantially more atherogenic than cholesterol-replete particles. These results lend further support to routine measurement of apoB in clinical care.

This study examines the risk of new-onset diabetes in patients with hypertriglyceridaemic hyperapolipoprotein B (high triglycerides, high apolipoprotein B [apoB], low LDL cholesterol to apoB ratio, and low HDL cholesterol). The aim was to establish whether this lipoprotein phenotype identified a substantial group at high risk of developing diabetes over the next 20 years.In this prospective, longitudinal, observational cohort study, we used data from the Framingham Offspring cohort (recruited in Framingham, MA, USA). Participants were aged 40-69 years and free of diabetes and cardiovascular disease at a baseline examination done between April, 1987, and November, 1991, and were followed up until March, 2014. Cox proportional hazards regression with hierarchical adjustment for age and sex, waist circumference, and fasting blood glucose were used to model the relationship between each lipid marker and incident diabetes, as well as the relationship between hypertriglyceridaemic hyperapoB (defined as values greater than sample medians of triglycerides and apoB, and less than medians of HDL cholesterol and LDL cholesterol to apoB ratio) and incident diabetes.Of 3446 individuals aged 40-69 years who completed baseline examination, 2515 participants were eligible and included in all analyses. During median 21·1 years (IQR 11·1-23·1) of follow-up, 402 (16·0%) individuals developed diabetes. Age (p=0·032), waist circumference (p0·0001), fasting blood glucose (p0·0001), and natural logarithm-transformed triglycerides (p0·0001) were associated with new-onset diabetes, as were apoB (p=0·0016), LDL cholesterol to apoB ratio (p=0·0018), and HDL cholesterol (p=0·0016) when added to this model. The age and sex-adjusted incidence of diabetes in the hypertriglyceridaemic hyperapoB group was 32·4% (95% CI 27·8-37·7) versus 5·5% (3·5-8·6) in the optimal lipid phenotype group and 15·5% (13·5-17·7) in the mixed lipid phenotype group. The fully adjusted hazard ratio, including glucose and waist circumference, for individuals with hypertriglyceridaemic hyperapoB was 3·30 (95% CI 2·06-5·30; p=0·0008) and for mixed lipid phenotype was 2·17 (1·38-3·40; p0·0001) compared with those with the optimal lipid phenotype.Our findings suggest that individuals with hypertriglyceridaemic hyperapoB are at high risk of new-onset diabetes and might benefit from intensive measures to prevent diabetes. The association between this phenotype and incident diabetes is consistent with a pro-diabetic effect due to increased clearance of apoB particles from plasma, which could injure pancreatic islet cells. This mechanism might explain the increased risk of diabetes with statin therapy.Doggone Foundation.

Introduction: HDL particles vary in size and concentration. Indices of overall HDL particle concentration (HDL-P) and the concentrations of different HDL size subspecies (small: H1-H3, medium: H4, H5, and large: H6, H7) have differential associations with near-term CVD events in middle-aged adults. It is unclear if measures of HDL particle concentration predict long-term ASCVD risk in young adults. Methods: Among CARDIA participants (ppts), NMR was used to measure HDL-P and HDL particle size subgroup H1-H7 concentrations. HDL cholesterol (HDL-C) was measured using standard assays. We stratified the ppts into 2 age windows: 20-30y (n= 1645) and 30-40y (n=2922). We used adjusted Cox proportional hazards models to assess the associations between a 1SD higher HDL-C, HDL-P, and HDL1-7 subgroups with incident ASCVD events. We added HDL-P, HDL H1-H7, and HDL-C separately to a modified Pooled Cohort Equation (PCE) model; model performance (discrimination and reclassification) was evaluated. Results: 81 and 163 ASCVD events occurred over (median (IQR)) 31.8y (31.1-32.0y) for the 20-30y age window and over 26.8y (19.1-27.1y) for the 30-40y age window, respectively. In ppts age 20-30y, a higher HDL-P and HDL-C were not associated with ASCVD events, however a higher HDL H6 subgroup level was associated with lower risk for ASCVD in demographic adjusted models. In the age 30-40y group, higher HDL-P, HDL-C, and H6 subgroup were significantly associated with lower ASCVD risks in all models. There were no significant differences in c-statistics across PCE models. However, there were improvements in reclassification for all HDL measures when added to the PCE model in the 20-30y age window, and significant improvements in reclassification when HDL H1-7 were added to the PCE for the 30-40y age window. Conclusion: At younger ages (

Introduction: Measures of atherogenic particle number (apoB and LDL particle number [LDL-P]) are stronger predictors of atherosclerotic cardiovascular disease (ASCVD) risk than measures of cholesterol concentration (LDL-C, non-HDL-C, total cholesterol [TC]) in middle-aged adults. It is unclear if this is true for younger adults. Methods: Among CARDIA participants (ppts), NMR was used to measure apoB and LDL-P. Non-HDL-C and TC were measured using standard assays; LDL-C was calculated using the Friedewald equation. We stratified the ppts into two age windows: age 20-30y (n=1645) and age 30-40y (n=2922). We used adjusted Cox proportional hazards models to assess the associations of 1SD higher apoB, LDL-P, non-HDL-C, LDL-C, or TC with incident ASCVD events. We substituted each measure of atherogenic lipid burden for TC in a modified Pooled Cohort Equation (PCE) model (with and without HDL-C); and model performance (discrimination and reclassification) was evaluated. Results: There were 81 and 163 ASCVD events over (median [IQR]) 31.8y (31.1-32.0y) for the age 20-30 age window and over 26.8y (19.1-27.1y) for the 30-40y age window, respectively. In ppts age 20-30y, a 1SD higher apoB, LDL-P, non-HDL-C, and LDL-C were significantly associated with incident ASCVD in demographic adjusted models. The strengths of associations with ASCVD were not significantly different across these measures. For the 30-40y age window, all measures of atherogenic lipoproteins were significantly associated with ASCVD; the strengths of association were not significantly different across atherogenic lipid measures in all models. There were no significant differences in the C-statistic and no improvement in reclassification when each measure was used to replace TC in the PCE model. Conclusions: ApoB, LDL-P, LDL-C or non-HDL-C may be slightly better markers of long-term ASCVD risk than TC in adults < 30y. However, in adults between 30-40y all measures of atherogenic lipid burden appeared to be equivalent predictors of long-term risk.

Context Selective androgen receptor modulators (SARMs), because of their preferential muscle vs prostate selectivity, are being developed for muscle-wasting conditions. Oral SARMs suppress high-density lipoprotein cholesterol (HDL-C) but their effects on functional capacity and atherogenic potential of HDL particles are unknown. Objective To determine the effects of an oral SARM (OPK-88004) on cholesterol efflux capacity, HDL particle number and size, apolipoprotein particle number and size and HDL subspecies Methods We measured cholesterol efflux capacity (CEC); HDL particle number and size; APOB; APOA1; and protein-defined HDL subspecies associated with coronary heart disease (CHD) risk in men, who had undergone prostatectomy for low-grade prostate cancer during 12-week treatment with placebo or 1, 5, or 15 mg of an oral SARM (OPK-88004). Results SARM significantly suppressed HDL-C (P Conclusion SARM treatment suppressed HDL-C but had minimal effect on its size or cholesterol efflux function. SARM reduced APOA1 in HDL subspecies associated with increased as well as decreased CHD risk. SARM-induced increase in HTGL could contribute to HDL-C suppression. These data do not support the simplistic notion that SARM-associated suppression of HDL-C is necessarily proatherogenic; randomized trials are needed to determine SARM’s effects on cardiovascular events.

Background: Lipid-lowering recommendations for prevention of atherosclerotic cardiovascular disease rely principally on estimated 10-year risk. We sought to determine the optimal time for initiation of lipid lowering in younger adults as a function of expected 30-year benefit. Methods: Data from 3148 National Health and Nutrition Examination Survey (2009–2016) participants, age 30 to 59 years, not eligible for lipid-lowering treatment recommendation under the most recent US guidelines, were analyzed. We estimated the absolute and relative impact of lipid lowering as a function of age, age at initiation, and non–high-density lipoprotein cholesterol (HDL-C) level on the expected rates of atherosclerotic cardiovascular disease over the succeeding 30 years. We modeled expected risk reductions based on shorter-term effects observed in statin trials (model A) and longer-term benefits based on Mendelian randomization studies (model B). Results: In both models, potential reductions in predicted 30-year atherosclerotic cardiovascular disease risk were greater with older age and higher non–HDL-C level. Immediate initiation of lipid lowering (ie, treatment for 30 years) in 40- to 49-year-old patients with non–HDL-C ≥160 mg/dL would be expected to reduce their average predicted 30-year risk of 17.1% to 11.6% (model A; absolute risk reduction [ARR], 5.5%) or 6.5% (model B; ARR 10.6%). Delaying lipid lowering by 10 years (treatment for 20 years) would result in residual 30-year risk of 12.7% (A; ARR 4.4) or 9.9% (B; ARR 7.2%) and delaying by 20 years (treatment for 10 years) would lead to expected mean residual risk of 14.6% (A; ARR 2.6%) or 13.9% (B; ARR 3.2%). The slope of the achieved ARR as a function of delay in treatment was also higher with older age and higher non–HDL-C level. Conclusions: Substantial reduction in expected atherosclerotic cardiovascular disease risk in the next 30 years is achievable by intensive lipid lowering in individuals in their 40s and 50s with non–HDL-C ≥160 mg/dL. For many, the question of when to start lipid lowering might be more relevant than whether to start lipid lowering.

Familial hypercholesterolemia (FH) is characterized as a monogenic, autosomal dominant disorder, producing severe hypercholesterolemia within families due to causal variants within genes regulating the low-density lipoprotein receptor pathway. Demonstration of a causal variant is widely accepted as evidence of substantially higher cardiovascular risk. However, recent large-scale population studies challenge this characterization of FH, which appears to account for only a minor portion of those with severe hypercholesterolemia. Moreover, a substantial portion of FH variant positive patients do not have marked hypercholesterolemia. These discordances raise doubt as to how FH should be defined and how the concentration of low-density lipoprotein in plasma is regulated in individuals with and without FH. Moreover, review of the evidence suggests the impact of an FH causal variant on cardiovascular risk may be less than previously accepted and that all patients with severe hypercholesterolemia should be prioritized for therapy and family screening.

Background ApoAI (apolipoproteins AI) and apoAII (apolipoprotein AII) are structural and functional proteins of high‐density lipoproteins (HDL) which undergo post‐translational modifications at specific residues, creating distinct proteoforms. While specific post‐translational modifications have been reported to alter apolipoprotein function, the full spectrum of apoAI and apoAII proteoforms and their associations with cardiometabolic phenotype remains unknown. Herein, we comprehensively characterize apoAI and apoAII proteoforms detectable in serum and their post‐translational modifications and quantify their associations with cardiometabolic health indices. Methods and Results Using top‐down proteomics (mass‐spectrometric analysis of intact proteins), we analyzed paired serum samples from 150 CARDIA (Coronary Artery Risk Development in Young Adults) study participants from year 20 and 25 exams. Measuring 15 apoAI and 9 apoAII proteoforms, 6 of which carried novel post‐translational modifications, we quantified associations between percent proteoform abundance and key cardiometabolic indices. Canonical (unmodified) apoAI had inverse associations with HDL cholesterol and HDL‐cholesterol efflux, and positive associations with obesity indices (body mass index, waist circumference), and triglycerides, whereas glycated apoAI showed positive associations with serum glucose and diabetes mellitus. Fatty‐acid‒modified ApoAI proteoforms had positive associations with HDL cholesterol and efflux, and inverse associations with obesity indices and triglycerides. Truncated and dimerized proteoforms of apoAII were associated with HDL cholesterol (positively) and obesity indices (inversely). Several proteoforms had no significant associations with phenotype. Conclusions Associations between apoAI and AII and cardiometabolic indices are proteoform‐specific. These results provide “proof‐of‐concept” that precise chemical characterization of human apolipoproteins will yield improved insights into the complex pathways through which proteins signify and mediate health and disease.

Background Apolipoprotein B (apoB) is emerging as the lipoprotein entity that is critical for the role that lipoprotein lipids play in the aetiology of coronary heart disease (CHD). In this study, we explored effects of genetically-predicted apoB on endpoints in first-degree relatives. Methods Univariable Mendelian randomization (MR) used a weighted genetic instrument (229 SNPs) for apoB. For endpoints that apoB associated with at FDR Findings Parents were less likely to be alive with 10.7 months of life lost in fathers (95%CI: 7.6, 13.9; FDR-adjusted P=4.0×10−10) and 5.8 months of life lost in mothers (95%CI: 3.0, 8.52; FDR-adjusted P=1.7×10−4) per 1-SD higher apoB in offspring. Effects strengthened to ∼2 yrs of life lost in multivariable MR and replicated in conventional two-sample MR (OR surviving to 90th centile: 0.38; 95%CI: 0.22, 0.65). Genetically-elevated apoB caused higher risks of heart disease in all first-degree relatives and higher risk of stroke in mothers. Findings in first-degree relatives were replicated in two-sample multivariable MR which identified apoB to increase (OR 2.32; 95%CI: 1.49, 3.61) and LDL-C lower (OR 0.34; 95%CI: 0.21, 0.54) risk of T2D. Interpretation Higher apoB shortens the lifespan, and increases risks of heart disease and stroke. T2D effects may represent injurious effects of dyslipidaemia to pancreatic islets. Research in Context Evidence before this study Prior observational and Mendelian randomization studies have indicated that circulating concentrations of apoB are of critical importance to lipid-mediated atherogenesis, manifest as coronary heart disease. Added value of this study In this study, we explored the effects of genetically-predicted elevations in apoB on multiple endpoints occuring in first degree relatives including longevity and sought replication of findings using more conventional methods to exploit the statistical power from data available in large-scale GWAS consortia. We identified that apoB had a deleterious effect on longevity, shortening the lifespan by months to years. Furthermore, apoB caused higher risks of CHD and stroke in first degree relatives. Finally, apoB was identified to increase risk of T2D, in contradistinction to LDL-C which lowered risk of T2D, when employing multivairable MR methods. Implications of all the available evidence Our findings support apoB as being the major lipoprotein entity critical for CHD and stroke and extends this to identify higher apoB as negatively impacting longevity and increasing risk of T2D. These findings highlight the critical role of apoB in causing cardiometabolic disease, which collectively shortens the lifespan.

Introduction Dysbetalipoproteinaemia (HLP3) is a disorder characterized by excess cholesterol-enriched, triglyceride-rich lipoprotein remnants in genetically predisposed individuals that powerfully promote premature cardiovascular disease if untreated. The current prevalence of HLP3 is largely unknown. Material and methods We performed cross-sectional analysis of 128,485 U.S. adults from the Very Large Database of Lipids (VLDbL), using four algorithms to diagnose HLP3 employing three Vertical Auto Profile ultracentrifugation (UC) criteria and a previously described apolipoprotein B (apoB) method. We evaluated 4,926 participants from the 2011-2014 National Health and Nutrition Examination Survey (NHANES) with the apoB method. We examined demographic and lipid characteristics stratified by presence of HLP3 and evaluated lipid characteristics in those with HLP3 phenotype discordance and concordance as determined by apoB and originally defined UC criteria 1. Results In U.S. adults in VLDbL and NHANES, a 1.7-2.0% prevalence is observed for HLP3 with the novel apoB method as compared to 0.2-0.8% prevalence in VLDbL via UC criteria 1-3. Participants who were both apoB and UC criteria HLP3 positive had higher remnant particles as well as more elevated triglyceride/apoB and total cholesterol/apoB ratios (all p < 0.001) than those who were apoB method positive and UC criteria 1 negative. Conclusions HLP3 may be more prevalent than historically and clinically appreciated. The apoB method increases HLP3 identification via inclusion of milder phenotypes. Further work should evaluate the clinical implications of HLP3 diagnosis at various lipid algorithm cut-points to evaluate the ideal standard in the modern era.

Background Extended elevations of non–high-density lipoprotein cholesterol (non–HDL-C) across a lifespan are associated with increased risk of cardiovascular disease (CVD). However, optimal testing intervals to identify individuals with high lipid-related CVD risk are unknown. Objectives This study determined the extent to which lipid levels in young adulthood predict future lipid trajectories and associated long-term CVD risk. Methods A sample of 2,516 Framingham Offspring study participants 25 to 40 years of age free of CVD and diabetes had their non–HDL-C progression modeled over 8 study examinations (mean follow-up 32.6 years) using group-based methods. CVD risk based on 25 to 30 years of follow-up was evaluated using Kaplan-Meier analyses for those with mean non–HDL-C ≥160 mg/dl (“high”) and Results The trajectories of the lipid levels were generally stable over the 30-year life course; mean non–HDL-C measured in young adulthood were highly predictive of levels later in life. Individuals could be reliably assigned to high and low non–HDL-C groups based on 2 measurements collected between 25 to 40 years of age. Overall, 80% of those with non–HDL-C ≥160 mg/dl at the first 2 exams remained in the high group on subsequent 25-year testing, whereas 88% of those with non–HDL-C Conclusions Most adults with elevated non–HDL-C early in life continue to have high non–HDL-C over their life course, leading to significantly increased risk of CVD. The results demonstrate that early lipid monitoring before 40 years of age would identify a majority of those with a high likelihood for lifetime elevated lipid levels who also have a high long-term risk for CVD. This information could facilitate informed patient–provider discussion about the potential benefits of preventive lipid-lowering efforts during the early midlife period.

Supplemental Digital Content is available in the text., Background: To optimize preventive strategies for coronary heart disease (CHD), it is essential to understand and appropriately quantify the contribution of its key risk factors. Our objective was to compare the associations of key modifiable CHD risk factors—specifically lipids, systolic blood pressure (SBP), diabetes mellitus, and smoking—with incident CHD events based on their prognostic performance, attributable risk fractions, and treatment benefits, overall and by age. Methods: Pooled participant-level data from 4 observational cohort studies sponsored by the National Heart, Lung, and Blood Institute were used to create a cohort of 22 626 individuals aged 45 to 84 years who were initially free of cardiovascular disease. Individuals were followed for 10 years from baseline evaluation for incident CHD. Proportional hazards regression was used to estimate metrics of prognostic model performance (likelihood ratio, C index, net reclassification, discrimination slope), hazard ratios, and population attributable fractions for SBP, non–high-density lipoprotein cholesterol (non–HDL-C), diabetes mellitus, and smoking. Expected absolute risk reductions for antihypertensive and lipid-lowering treatment were assessed. Results: Age, sex, and race capture 63% to 80% of the prognostic performance of cardiovascular risk models. In contrast, adding either SBP, non–HDL-C, diabetes mellitus, or smoking to a model with other risk factors increases the C index by only 0.004 to 0.013. However, primordial prevention could have a substantial effect as demonstrated by population attributable fractions of 28% for SBP≥130 mm Hg and 17% for non–HDL-C≥130 mg/dL. Similarly, lowering the SBP of all individuals to

Purpose of review The 2019 European Society of Cardiology/European Atherosclerosis Society Guidelines concluded that apolipoprotein B (apoB) was a more accurate measure of cardiovascular risk and a better guide to the adequacy of lipid lowering than low-density lipoprotein cholesterol (LDL-C) or non-high-density lipoprotein cholesterol (HDL-C). Also, they stated that apoB can be measured more accurately than LDL-C or non-HDL-C. This strong endorsement of the central role of apoB contrasts with the limited endorsement of apoB by the 2018 American College of Cardiology/American Heart Association Multisociety Guidelines. Nevertheless, both retained LDL-C as the primary metric to guide statin/ezetimibe/Proprotein convertase subtilisin/kexin type 9 (PCSK9) therapy. Recent findings This essay will review the most important recent advances in knowledge about apoB with particular emphasis on the results of Mendelian randomization studies and a new discordance analysis in subjects on statin therapy. We will also lay out why using LDL-C to guide the adequacy of lipid lowering therapy represents an interpretive error of the results of the statin/ezetimibe/PCSK9 inhibitor randomized clinical trials and therefore why apoB should be the primary metric to guide statin/ezetimibe/PCSK9 therapy. Summary There is now a robust body of evidence demonstrating the superiority of apoB over LDL-C and non-HDL-C as a clinical marker of cardiovascular risk. LDL-C is not the appropriate marker to assess the benefits of statin/ezetimibe/PCSK9 therapy.

Background and aims: Apolipoprotein B (apoB) integrates and extends the information from the conventional measures of atherogenic cholesterol and triglyceride. To illustrate how apoB could simplify and improve the management of dyslipoproteinemia, we compared conventional lipid markers and apoB in a sample of Americans and Asian Indians.Methods: Data from the US National Health and Nutrition Examination Survey (NHANES) (11,778 participants, 2009–2010, 2011–2012), and the Centre for Cardiometabolic Risk Reduction in South Asia (CARRS) cohort study in Delhi, India (4244 participants), 2011 were evaluated. We compared means and distributions of plasma lipids, and apo B using the Mann–Whitney U test and Fisher’s exact test. A p value of < 0.05 was considered significant.Results: The plasma lipid profile differed between Asian Indians and Americans. Plasma triglycerides were greater, but HDL-C lower in Asian Indians than in Americans. By contrast, total cholesterol, non-HDL-C, and LDL-C were all significantly higher in Americans than Asian Indians. However, apoB was significantly higher in Asian Indians than Americans. The LDL-C/apoB ratio and the non-HDL-C/apoB ratio were both significantly lower in Asian Indians than Americans.Conclusion: Whether Americans or Asian Indians are at higher risk from apoB lipoproteins cannot be determined based on their lipid levels because the information from lipids cannot be integrated. ApoB, however, integrates and extends the information from triglycerides and cholesterol. Replacing the conventional lipid panel with apoB for routine follow ups could simultaneously simplify and improve clinical care.

The apparently endless debate whether apolipoprotein B (apoB) significantly improves the identification of those at high risk of cardiovascular disease and the treatment of those with cardiovascular disease or at high risk of cardiovascular disease is over. The evidence from multiple prospective observational studies has been extended dramatically by multiple discordance analyses. Taken together, this body of evidence demonstrates, unequivocally, that apoB is superior to both LDL-C and non-HDL-C as a marker of cardiovascular risk. Furthermore, the evidence from multiple randomized clinical trials establishes that apoB is superior to both LDL-C and non-HDL-C as a marker of the benefit possible from lipid-lowering therapy. To this has been added transformative evidence from Mendelian randomization analyses, which demonstrates that the clinical benefit from therapy relates more directly to the decrease in number of apoB particles than to the decrease in LDL-C and the atherogenic risk attributable to a very-low-density lipoprotein (VLDL) apoB particle is the same as that due to a LDL apoB particle. Accordingly, the debate should now be whether the conventional lipid panel, including total cholesterol, triglyceride, LDL cholesterol, and non-HDL cholesterol, adds anything to apoB. Since the evidence indicates it does not, for routine care, why not just measure apoB? The reality is that the conventional lipid panel is complex, contradictory, and confusing and apoB would allow diagnosis and care to be simpler and better. If our care is to be evidence-based, apoB should be introduced into routine clinical care.

The triglyceride (TG) synthetic pathway is believed to be regulated at the level of the rate-limiting enzyme acyl-CoA:1,2-diacylglycerol O-acyltransferase (DGAT). Recent reports using rat hepatic tissue suggest a kinase-dependent mechanism for the regulation of DGAT activity. To examine this process further, the present study investigates the regulatory mechanisms involved in the modulation of DGAT in human adipocytes. Adipocytes were fractionated into a microsomal fraction containing DGAT and a cytosolic fraction containing a putative regulatory kinase. DGAT activity was determined bymeasuring the incorporation of 14C-oleoyl-CoA into TG with exogenously supplied 1,2-dioleoyl-sn-glycerol. Kinase activity was assayed by addition of the cytosolic fraction in the presence of Mg2+ and ATP. The results indicate a significant inhibition of human adipose tissue DGAT activity by as much as 43% (avg: 17.5% ± 10.4%, p < 0.01) via a mechanism consistent with a phosphorylation event. Partial purification of the putative cytosolic kinase was achieved by multidimensional chromatography. This study thus provides evidence for a novel and key regulatory step in the human TG biosynthetic pathway. Further research is necessary to determine whether the model outlined here is a physiologic conduit through which extracellular hormones exert a regulatory influence on TG synthesis.

IMPORTANCE: Lipid management typically focuses on levels of low-density lipoprotein cholesterol (LDL-C) and, to a lesser extent, triglycerides (TG). However, animal models and genetic studies suggest that the atherogenic particle subpopulations (LDL and very-low-density lipoprotein [VLDL]) are both important and that the number of particles is more predictive of cardiac events than their lipid content. OBJECTIVE: To determine whether common measures of cholesterol concentration, TG concentration, or their ratio are associated with cardiovascular risk beyond the number of apolipoprotein B (apoB)–containing lipoproteins. DESIGN, SETTING, AND PARTICIPANTS: This prospective cohort analysis included individuals from the population-based UK Biobank and from 2 large international clinical trials, FOURIER and IMPROVE-IT. The median (IQR) follow-up was 11.1 (10.4-11.8) years in UK Biobank and 2.5 (2.0-4.7) years in the clinical trials. Two populations were studied in this analysis: 389 529 individuals in the primary prevention group who were not taking lipid-lowering therapy and 40 430 patients with established atherosclerosis who were receiving statin treatment. EXPOSURES: ApoB, non–high-density lipoprotein cholesterol (HDL-C), LDL-C, and TG. MAIN OUTCOME AND MEASURES: The primary study outcome was incident myocardial infarction (MI). RESULTS: Of the 389 529 individuals in the primary prevention group, 224 097 (58%) were female, and the median (IQR) age was 56.0 (49.5-62.5) years. Of the 40 430 patients with established atherosclerosis, 9647 (24%) were female, and the median (IQR) age was 63 (56.2-69.0) years. In the primary prevention cohort, apoB, non–HDL-C, and TG each individually were associated with incident MI. However, when assessed together, only apoB was associated (adjusted hazard ratio [aHR] per 1 SD, 1.27; 95% CI, 1.15-1.40; P

Purpose of review This review summarizes the evidence that apolipoprotein B (apoB) integrates the conventional lipid markers - total cholesterol, triglycerides, LDL-cholesterol, and non-HDL-cholesterol - into a single index that accurately and simply quantitates the atherogenic risk due to the apoB lipoprotein particles. Recent findings Marked hypertriglyceridemia remains the essential signal for hyperchylomicronemia and potential pancreatitis. However, with the exception of Lp(a) and the abnormal cholesterol-enriched remnant particles that are the hallmark of type III hyperlipoproteinemia, recent evidence from discordance analyses and Mendelian randomization indicate that apoB integrates the risk due to the atherogenic lipoprotein particles because all LDL particles are, within the limits of our ability to measure any differences, equally atherogenic and all, except the largest VLDL particles are, within the limits of our ability to measure any differences, equally atherogenic. Summary Measuring apoB as well as the conventional lipids is essential for accurate diagnosis. For almost all follow-up, however, apoB is all that need be measured. ApoB is the Rosetta Stone of lipidology because dyslipoproteinemia cannot be understood unless apoB is measured.

BackgroundApolipoprotein B (apoB) is emerging as the lipoprotein entity that is critical for the role that lipoprotein lipids play in the aetiology of coronary heart disease (CHD). In this study, we explored effects of genetically-predicted apoB on endpoints in first-degree relatives.MethodsUnivariable Mendelian randomization (MR) used a weighted genetic instrument (229 SNPs) for apoB. For endpoints that apoB associated with at FDR FindingsParents were less likely to be alive with 10.7 months of life lost in fathers (95%CI: 7.6, 13.9; FDR-adjusted P=4.0×10−10) and 5.8 months of life lost in mothers (95%CI: 3.0, 8.52; FDR-adjusted P=1.7×10−4) per 1-SD higher apoB in offspring. Effects strengthened to ∼2 yrs of life lost in multivariable MR and replicated in conventional two-sample MR (OR surviving to 90thcentile: 0.38; 95%CI: 0.22, 0.65). Genetically-elevated apoB caused higher risks of heart disease in all first-degree relatives and higher risk of stroke in mothers.Findings in first-degree relatives were replicated in two-sample multivariable MR which identified apoB to increase (OR 2.32; 95%CI: 1.49, 3.61) and LDL-C lower (OR 0.34; 95%CI: 0.21, 0.54) risk of T2D.InterpretationHigher apoB shortens the lifespan, and increases risks of heart disease and stroke. T2D effects may represent injurious effects of dyslipidaemia to pancreatic islets.Research in ContextEvidence before this studyPrior observational and Mendelian randomization studies have indicated that circulating concentrations of apoB are of critical importance to lipid-mediated atherogenesis, manifest as coronary heart disease.Added value of this studyIn this study, we explored the effects of genetically-predicted elevations in apoB on multiple endpoints occuring in first degree relatives including longevity and sought replication of findings using more conventional methods to exploit the statistical power from data available in large-scale GWAS consortia. We identified that apoB had a deleterious effect on longevity, shortening the lifespan by months to years. Furthermore, apoB caused higher risks of CHD and stroke in first degree relatives. Finally, apoB was identified to increase risk of T2D, in contradistinction to LDL-C which lowered risk of T2D, when employing multivairable MR methods.Implications of all the available evidenceOur findings support apoB as being the major lipoprotein entity critical for CHD and stroke and extends this to identify higher apoB as negatively impacting longevity and increasing risk of T2D. These findings highlight the critical role of apoB in causing cardiometabolic disease, which collectively shortens the lifespan.

Guidelines propose using non-HDL cholesterol or apolipoprotein (apo) B as a secondary treatment target to reduce residual cardiovascular risk of LDL-targeted therapies. This review summarizes the strengths, weaknesses, opportunities, and threats (SWOT) of using apoB compared with non-HDL cholesterol. Non-HDL cholesterol, calculated as total-HDL cholesterol, includes the assessment of remnant lipoprotein cholesterol, an additional risk factor independent of LDL cholesterol. ApoB is a direct measure of circulating numbers of atherogenic lipoproteins, and its measurement can be standardized across laboratories worldwide. Discordance analysis of non-HDL cholesterol versus apoB demonstrates that apoB is the more accurate marker of cardiovascular risk. Baseline and on-treatment apoB can identify elevated numbers of small cholesterol-depleted LDL particles that are not reflected by LDL and non-HDL cholesterol. ApoB is superior to non-HDL cholesterol as a secondary target in patients with mild-to-moderate hypertriglyceridemia (175–880 mg/dL), diabetes, obesity or metabolic syndrome, or very low LDL cholesterol

Background The ESC/EAS Guidelines and the EAS/EFLM consensus reports state that apoB is a more accurate marker of cardiovascular risk than LDL-C or non-HDL-C and that apoB can be measured accurately and precisely than LDL-C or non-HDL-C. Nevertheless, EAS/EFLM called for a randomized clinical trial and a cost-effective analysis before widespread implementation of apoB. Objective To analyse these issues from the perspective of clinical utility as clinical utility would be considered by an informed patient and physician. Methods and results We highlight the biological inaccuracies as well as the laboratory inaccuracies of LDL-C/non-HDL-C versus apoB. We demonstrate why the biological variance in the cholesterol loading per apoB particle makes it impossible to design a randomized clinical trial to compare apoB to LDL-C/non-HDL-C. We further demonstrate that even in the context of the United States, adding apoB to a lipid panel would have only a trivial effect on costs. Conclusion We submit that no informed patient or physician would choose a less accurate test over a more accurate test if the more accurate test added only trivially to the total cost of care. For these reasons, the clinical utility of apoB far exceeds the clinical utility of LDL-C/non-HDL-C.

Supplemental Digital Content is available in the text., Background: Total cholesterol and high-density lipoprotein cholesterol (HDL-C) measurements are central to cardiovascular disease (CVD) risk assessment, but there is continuing debate around the utility of other lipids for risk prediction. Methods: Participants from UK Biobank without baseline CVD and not taking statins, with relevant lipid measurements (n=346 686), were included in the primary analysis. An incident fatal or nonfatal CVD event occurred in 6216 participants (1656 fatal) over a median of 8.9 years. Associations of nonfasting lipid measurements (total cholesterol, HDL-C, non–HDL-C, direct and calculated low-density lipoprotein cholesterol [LDL-C], and apolipoproteins [Apo] A1 and B) with CVD were compared using Cox models adjusting for classical risk factors, and predictive utility was determined by the C-index and net reclassification index. Prediction was also tested in 68 649 participants taking a statin with or without baseline CVD (3515 CVD events). Results: ApoB, LDL-C, and non–HDL-C were highly correlated (r>0.90), while HDL-C was strongly correlated with ApoA1 (r=0.92). After adjustment for classical risk factors, 1 SD increase in ApoB, direct LDL-C, and non–HDL-C had similar associations with composite fatal/nonfatal CVD events (hazard ratio, 1.23, 1.20, 1.21, respectively). Associations for 1 SD increase in HDL-C and ApoA1 were also similar (hazard ratios, 0.81 [both]). Adding either total cholesterol and HDL-C, or ApoB and ApoA, to a CVD risk prediction model (C-index, 0.7378) yielded similar improvement in discrimination (C-index change, 0.0084; 95% CI, 0.0065, 0.0104, and 0.0089; 95% CI, 0.0069, 0.0109, respectively). Once total and HDL-C were in the model, no further substantive improvement was achieved with the addition of ApoB (C-index change, 0.0004; 95% CI, 0.0000, 0.0008) or any measure of LDL-C. Results for predictive utility were similar for a fatal CVD outcome, and in a discordance analysis. In participants taking a statin, classical risk factors (C-index, 0.7118) were improved by non–HDL-C (C-index change, 0.0030; 95% CI, 0.0012, 0.0048) or ApoB (C-index change, 0.0030; 95% CI, 0.0011, 0.0048). However, adding ApoB or LDL-C to a model already containing non–HDL-C did not further improve discrimination. Conclusions: Measurement of total cholesterol and HDL-C in the nonfasted state is sufficient to capture the lipid-associated risk in CVD prediction, with no meaningful improvement from addition of apolipoproteins, direct or calculated LDL-C.

Top-down proteomics (TDP) allows precise determination/characterization of the different proteoforms derived from the expression of a single gene. In this study, we targeted apolipoprotein A-I (ApoA-I), a mediator of high-density-lipoprotein cholesterol efflux (HDL-E), which is inversely associated with coronary heart disease risk. Absolute ApoA-I concentration and allelic variation only partially explain interindividual HDL-E variation. Therefore, we hypothesize that differences in HDL-E are associated with the abundances of different ApoA-I proteoforms. Here, we present a targeted TDP methodology to characterize ApoA-I proteoforms in serum samples and compare their abundances between individuals. We characterized 18 ApoA-I proteoforms using selected-ion monitoring coupled to electron-transfer dissociation mass spectrometry. We then compared the abundances of these proteoforms between two groups of four participants, representing the individuals with highest and lowest HDL-E values within the Chicago Healthy Aging Study ( n = 420). Six proteoforms showed significantly ( p0.0005) higher intensity in high HDL-E individuals: canonical ApoA-I [fold difference (fd) = 1.17], carboxymethylated ApoA-I (fd = 1.24) and, with highest difference, four fatty acylated forms: palmitoylated (fd = 2.16), oleoylated (fd = 2.08), arachidonoylated (fd = 2.31) and one bearing two modifications: palmitoylation and truncation (fd = 2.13). These results demonstrate translational potential for targeted TDP in revealing, with high sensitivity, associations between interindividual proteoform variation and physiological differences underlying disease risk.

Triglycerides are the conventional tool to measure VLDLs, whereas LDL cholesterol (LDL-C) is the conventional tool to measure LDLs. Multiple epidemiological studies, including a series of genetically based analyses, have demonstrated that cardiovascular risk is related to triglycerides independently of LDL-C, and this has led to a series of new therapeutic agents designed specifically to reduce plasma triglycerides. The triglyceride hypothesis posits that increased levels of triglycerides increase cardiovascular risk and decreasing plasma triglycerides decreases cardiovascular risk. In this work, we will examine the validity of the triglyceride hypothesis by detailing the biological complexities associated with hypertriglyceridemia, the genetic epidemiological evidence in favor of hypertriglyceridemia, the evidence from the fibrate randomized clinical trials relating triglycerides and clinical outcomes, and the completeness of the evidence from the initial studies of novel mutations and the therapeutic agents based on these mutations that lower triglycerides. Because of the multiple metabolic links between VLDL and LDL, we will try to demonstrate that measuring triglycerides and LDL-C alone are inadequate to document the lipoprotein profile. We will try to demonstrate that apoB must be measured, as well as triglycerides and cholesterol, to have an accurate estimate of lipoprotein status.

Cardiovascular risk is so high in type III hyperlipoproteinemia that type III, just like heterozygous familial hypercholesterolemia (FH)2, is a treat-on-diagnosis disorder (1–3). Tragically, although severe hypercholesterolemia is easy to recognize, type III hyperlipoproteinemia cannot be diagnosed using a conventional lipid panel (4) and the original diagnostic tools—electrophoresis and ultracentrifugation—are available in only a miniscule number of clinics (1). Thus, type III cannot be diagnosed in regular clinical care using regular diagnostic tools. Moreover, while the importance of FH is recognized by all the major lipid guidelines, even the existence of type III hyperlipoproteinemia is barely acknowledged, if at all, by the same groups. Consequently, those patients with type III are lumped and dumped with all the others with mixed hyperlipidemia and the result, tragically, can be no treatment when treatment is indicated. In a wonderful paper (3), Paul Hopkins and his colleagues referred to type III hyperlipoproteinemia as the “forgotten phenotype.” Nothing has changed and so the extended title of this editorial. In this issue of Clinical Chemistry , Boot et al. (5) present the advantages of the non-HDL cholesterol (non-HDL-C)/apoB ratio as a diagnostic tool for type III hyperlipoproteinemia. I congratulate them on their work, notwithstanding that their results and conclusions, using their approach, differ at the margins from our results and conclusions using our approach (4). On reflection, it may be that we were too rigid in one direction, while they may be too rigid in another. Nevertheless, what is most important is that the work is powerfully confirmatory of that of David Marais and his colleagues from South Africa, who diagnosed type III based on the total cholesterol (TC)/apoB ratio (6). I met Dr. Marais only once, and then only briefly, but his multiple contributions to the understanding of this disorder, while …

Aim This study aims to describe the variability of pre-dialysis troponin values in stable haemodialysis patients and compare the performance of single versus fluctuating or persistently elevated troponins in predicting a composite of mortality and cardiac arrest, myocardial infarction, or stroke. Methods 128 stable ambulatory chronic haemodialysis patients were enrolled. Pre-dialysis troponin I was measured for three consecutive months. The patients were followed for one year. A troponin elevation (>0.06 µg/L) was considered high risk, and patients were classified into 3 risk groups: 1) patients who had normal troponin levels on all three measurements; 2) patients with at least one elevated and one normal troponin value; 3) patients with elevated troponin values on all measurements. Results 81 patients had all three troponin values in the normal range; 29 had fluctuating values; 18 had all three values elevated. 27 deaths or composite events were observed: 8 in the first risk group, 10 in the second, and 9 in the third. Persistently elevated and fluctuating troponin values were associated with higher mortality and cardiovascular event rate. Serial troponin measurement had a higher sensitivity for the composite outcome than single troponin measurement when either fluctuating or persistently elevated values were considered to confer high risk. Conclusion Most haemodialysis patients do not have elevated troponin levels at baseline. Troponin levels that remain elevated or fluctuate are associated with worse outcomes. A serial troponin measurement strategy is associated with better sensitivity and higher negative predictive value compared with single troponin measurement.

Statins and PCSK9 inhibitors dramatically lower plasma LDL levels and dramatically increase LDL receptor number within hepatocyte cell membranes. It seems self-evident that total clearance of LDL particles from plasma and total delivery of cholesterol to the liver must increase in consequence. However, based on the results of stable isotope tracer studies, this analysis demonstrates the contrary to be the case. Statins do not change the production rate of LDL particles. Accordingly, at steady state, the clearance rate cannot change. Because LDL particles contain less cholesterol on statin therapy, the delivery of cholesterol to the liver must, therefore, be reduced. PCSK9 inhibitors reduce the production of LDL particles and this further reduces cholesterol delivery to the liver. With both agents, a larger fraction of a smaller pool is removed per unit time. These findings are inconsistent with the conventional model of cholesterol homeostasis within the liver, but are consistent with a new model of regulation, the multi-channel model, which postulates that different lipoprotein particles enter the hepatocyte by different routes and have different metabolic fates within the hepatocyte. The multi-channel model, but not the conventional model, may explain how statins and PCSK9 inhibitors can produce sustained increases in LDL receptor number.