Lipoprotein(a) is a highly atherogenic lipoprotein: pathophysiological basis and clinical implications.

PURPOSE OF REVIEW: Lipoprotein(a) has been identified as a causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and aortic valve stenosis. However, as reviewed here, there is ongoing debate as to the key pathogenic features of Lp(a) particles and the degree of Lp(a) atherogenicity relative to low-density lipoprotein (LDL). RECENT FINDINGS: Genetic analyses have revealed that Lp(a) on a per-particle basis is markedly (about six-fold) more atherogenic than LDL. Oxidized phospholipids carried on Lp(a) have been found to have substantial pro-inflammatory properties triggering pathways that may contribute to atherogenesis. Whether the strength of association of Lp(a) with ASCVD risk is dependent on inflammatory status is a matter of current debate and is critical to implementing intervention strategies. Contradictory reports continue to appear, but most recent studies in large cohorts indicate that the relationship of Lp(a) to risk is independent of C-reactive protein level. SUMMARY: Lp(a) is a highly atherogenic lipoprotein and a viable target for intervention in a significant proportion of the general population. Better understanding the basis of its enhanced atherogenicity is important for risk assessment and interpreting intervention trials.

Quantifying Triglyceride-Rich Lipoprotein Atherogenicity, Associations With Inflammation, and Implications for Risk Assessment Using Non-HDL Cholesterol.

BACKGROUND: Triglyceride-rich lipoproteins and remnants (TRL/remnants) have a causal, but not yet quantified, relationship with coronary heart disease (CHD): myocardial infarction plus revascularization. OBJECTIVES: The authors sought to estimate TRL/remnant per-particle atherogenicity, investigate causal relationships with inflammation, and determine whether differences in the atherogenicity of TRL/remnants and low-density lipoprotein (LDL) impact the causal association of non-high-density lipoprotein cholesterol (non-HDL-C) with CHD. METHODS: Single nucleotide polymorphisms (SNPs) (N = 1,357) identified by genome-wide association in the UK Biobank were ranked into 10 clusters according to the effect on TRL/remnant-C vs LDL-C. Mendelian randomization analysis was used to estimate for each SNP cluster CHD ORs per 10 mg/dL apolipoprotein B (apoB) and per 0.33 mmol/L non-HDL-cholesterol, and to evaluate association of TRL/remnants with biomarkers of systemic inflammation. RESULTS: SNPs in cluster 1 predominantly affected LDL-C, whereas SNPs in cluster 10 predominantly affected TRL/remnant-C. CHD risk per genetically predicted increase in apoB and in non-HDL-C rose across clusters. ORs per 10 mg/dL higher apoB was 1.15 (95% CI: 1.11-1.19) in cluster 1 vs 1.70 (95% CI: 1.52-1.90) in cluster 10. Comparing ORs between these TRL/remnant-predominant and LDL-predominant clusters, we estimated that TRL/remnants were at least 3.9 (95% CI: 2.8-5.4) times more atherogenic than LDL on a per-particle basis. For non-HDL-C, CHD ORs per 0.33 mmol/L rose from 1.15 (95% CI: 1.11-1.19) for cluster 1 to 1.40 (95% CI: 1.30-1.50) for cluster 10. TRL/remnants exhibited causal relationships with inflammation, but this did not explain their greater atherogenicity. CONCLUSIONS: TRL/remnants are about 4 times more atherogenic than LDL. Variation in the causal association of non-HDL-C with CHD indicates that adjustment for percentage TRL/remnant-C may be needed for accurate risk prediction.

Addressing residual risk beyond statin therapy: New targets in the management of dyslipidaemias-A report from the European Society of Cardiology Cardiovascular Round Table.

Cardiovascular (CV) disease is the most common cause of death in Europe. Despite proven benefits, use of lipid-lowering therapy remains suboptimal. Treatment goals are often not achieved, even in patients at high risk with atherosclerotic CV disease (ASCVD). The occurrence of CV events in patients on lipid-lowering drugs is defined as "residual risk", and can result from inadequate control of plasma lipids or blood pressure, inflammation, diabetes, and environmental hazards. Assessment of CV risk factors and vascular imaging can aid in the evaluation and management decisions for individual patients. Lifestyle measures remain the primary intervention for lowering CV risk. Where drug therapies are required to reach lipid treatment targets, their effectiveness increases when they are combined with lifestyle measures delivered through formal programs. However, lipid drug dosage and poor adherence to treatment remain major obstacles to event-free survival. This article discusses guideline-supported treatment algorithms beyond statin therapy that can help reduce residual risk in specific patient profiles while also likely resulting in substantial healthcare savings through better patient management and treatment adherence.

Biosynthesis and Metabolism of ApoB-Containing Lipoproteins.

Recent advances in human genetics, together with a substantial body of epidemiological, preclinical and clinical trial evidence, strongly support a causal relationship between triglyceride-rich lipoproteins (TRLs) and atherosclerotic cardiovascular disease. Consequently, the secretion and metabolism of TRLs have a significant impact on cardiovascular health. This knowledge underscores the importance of understanding the molecular mechanisms and regulation of very-low-density lipoprotein (VLDL) and chylomicron biogenesis. Fortunately, there has been a resurgence of interest in the intracellular assembly, trafficking, degradation, and secretion of VLDL, leading to many ground-breaking molecular insights. Furthermore, the identification of molecular control mechanisms related to triglyceride metabolism has greatly advanced our understanding of the complex metabolism of TRLs. In this review, we explore recent advances in the assembly, secretion, and metabolism of TRLs. We also discuss available treatment strategies for hypertriglyceridemia.

Lipoprotein(a) Is Markedly More Atherogenic Than LDL: An Apolipoprotein B-Based Genetic Analysis.

BACKGROUND: Lipoprotein(a) (Lp(a)) is recognized as a causal factor for coronary heart disease (CHD) but its atherogenicity relative to that of low-density lipoprotein (LDL) on a per-particle basis is indeterminate. OBJECTIVES: The authors addressed this issue in a genetic analysis based on the fact that Lp(a) and LDL both contain 1 apolipoprotein B (apoB) per particle. METHODS: Genome-wide association studies using the UK Biobank population identified 2 clusters of single nucleotide polymorphisms: one comprising 107 variants linked to Lp(a) mass concentration, the other with 143 variants linked to LDL concentration. In these Lp(a) and LDL clusters, the relationship of genetically predicted variation in apoB with CHD risk was assessed. RESULTS: The Mendelian randomization-derived OR for CHD for a 50 nmol/L higher Lp(a)-apoB was 1.28 (95% CI: 1.24-1.33) compared with 1.04 (95% CI: 1.03-1.05) for the same increment in LDL-apoB. Likewise, use of polygenic scores to rank subjects according to difference in Lp(a)-apoB vs difference in LDL-apoB revealed a greater HR for CHD per 50 nmol/L apoB for the Lp(a) cluster (1.47; 95% CI: 1.36-1.58) compared with the LDL cluster (1.04; 95% CI: 1.02-1.05). From these data, we estimate that the atherogenicity of Lp(a) is approximately 6-fold (point estimate of 6.6; 95% CI: 5.1-8.8) greater than that of LDL on a per-particle basis. CONCLUSIONS: We conclude that the atherogenicity of Lp(a) (CHD risk quotient per unit increase in particle number) is substantially greater than that of LDL. Therefore, Lp(a) represents a key target for drug-based intervention in a significant proportion of the at-risk population.

Exploring apolipoprotein C-III: pathophysiological and pharmacological relevance.

The availability of pharmacological approaches able to effectively reduce circulating LDL cholesterol (LDL-C) has led to a substantial reduction in the risk of atherosclerosis-related cardiovascular disease (CVD). However, a residual cardiovascular (CV) risk persists in treated individuals with optimal levels of LDL-C. Additional risk factors beyond LDL-C are involved, and among these, elevated levels of triglycerides (TGs) and TG-rich lipoproteins are causally associated with an increased CV risk. Apolipoprotein C-III (apoC-III) is a key regulator of TG metabolism and hence circulating levels through several mechanisms including the inhibition of lipoprotein lipase activity and alterations in the affinity of apoC-III-containing lipoproteins for both the hepatic receptors involved in their removal and extracellular matrix in the arterial wall. Genetic studies have clarified the role of apoC-III in humans, establishing a causal link with CVD and showing that loss-of-function mutations in the APOC3 gene are associated with reduced TG levels and reduced risk of coronary heart disease. Currently available hypolipidaemic drugs can reduce TG levels, although to a limited extent. Substantial reductions in TG levels can be obtained with new drugs that target specifically apoC-III; these include two antisense oligonucleotides, one small interfering RNA and an antibody.

Contribution of intestinal triglyceride-rich lipoproteins to residual atherosclerotic cardiovascular disease risk in individuals with type 2 diabetes on statin therapy.

AIMS/HYPOTHESIS: This study explored the hypothesis that significant abnormalities in the metabolism of intestinally derived lipoproteins are present in individuals with type 2 diabetes on statin therapy. These abnormalities may contribute to residual CVD risk. METHODS: To investigate the kinetics of ApoB-48- and ApoB-100-containing lipoproteins, we performed a secondary analysis of 11 overweight/obese individuals with type 2 diabetes who were treated with lifestyle counselling and on a stable dose of metformin who were from an earlier clinical study, and compared these with 11 control participants frequency-matched for age, BMI and sex. Participants in both groups were on a similar statin regimen during the study. Stable isotope tracers were used to determine the kinetics of the following in response to a standard fat-rich meal: (1) apolipoprotein (Apo)B-48 in chylomicrons and VLDL; (2) ApoB-100 in VLDL, intermediate-density lipoprotein (IDL) and LDL; and (3) triglyceride (TG) in VLDL. RESULTS: The fasting lipid profile did not differ significantly between the two groups. Compared with control participants, in individuals with type 2 diabetes, chylomicron TG and ApoB-48 levels exhibited an approximately twofold higher response to the fat-rich meal, and a twofold higher increment was observed in ApoB-48 particles in the VLDL1 and VLDL2 density ranges (all p < 0.05). Again comparing control participants with individuals with type 2 diabetes, in the latter, total ApoB-48 production was 25% higher (556 ± 57 vs 446 ± 57 mg/day; p < 0.001), conversion (fractional transfer rate) of chylomicrons to VLDL was around 40% lower (35 ± 25 vs 82 ± 58 pools/day; p=0.034) and direct clearance of chylomicrons was 5.6-fold higher (5.6 ± 2.2 vs 1.0 ± 1.8 pools/day; p < 0.001). During the postprandial period, ApoB-48 particles accounted for a higher proportion of total VLDL in individuals with type 2 diabetes (44%) compared with control participants (25%), and these ApoB-48 VLDL particles exhibited a fivefold longer residence time in the circulation (p < 0.01). No between-group differences were seen in the kinetics of ApoB-100 and TG in VLDL, or in LDL ApoB-100 production, pool size and clearance rate. As compared with control participants, the IDL ApoB-100 pool in individuals with type 2 diabetes was higher due to increased conversion from VLDL2. CONCLUSIONS/INTERPRETATION: Abnormalities in the metabolism of intestinally derived ApoB-48-containing lipoproteins in individuals with type 2 diabetes on statins may help to explain the residual risk of CVD and may be suitable targets for interventions. TRIAL REGISTRATION: ClinicalTrials.gov NCT02948777.

Triglyceride-rich lipoprotein remnants, low-density lipoproteins, and risk of coronary heart disease: a UK Biobank study.

AIMS: The strength of the relationship of triglyceride-rich lipoproteins (TRL) with risk of coronary heart disease (CHD) compared with low-density lipoprotein (LDL) is yet to be resolved. METHODS AND RESULTS: Single-nucleotide polymorphisms (SNPs) associated with TRL/remnant cholesterol (TRL/remnant-C) and LDL cholesterol (LDL-C) were identified in the UK Biobank population. In a multivariable Mendelian randomization analysis, TRL/remnant-C was strongly and independently associated with CHD in a model adjusted for apolipoprotein B (apoB). Likewise, in a multivariable model, TRL/remnant-C and LDL-C also exhibited independent associations with CHD with odds ratios per 1 mmol/L higher cholesterol of 2.59 [95% confidence interval (CI): 1.99-3.36] and 1.37 [95% CI: 1.27-1.48], respectively. To examine the per-particle atherogenicity of TRL/remnants and LDL, SNPs were categorized into two clusters with differing effects on TRL/remnant-C and LDL-C. Cluster 1 contained SNPs in genes related to receptor-mediated lipoprotein removal that affected LDL-C more than TRL/remnant-C, whereas cluster 2 contained SNPs in genes related to lipolysis that had a much greater effect on TRL/remnant-C. The CHD odds ratio per standard deviation (Sd) higher apoB for cluster 2 (with the higher TRL/remnant to LDL ratio) was 1.76 (95% CI: 1.58-1.96), which was significantly greater than the CHD odds ratio per Sd higher apoB in cluster 1 [1.33 (95% CI: 1.26-1.40)]. A concordant result was obtained by using polygenic scores for each cluster to relate apoB to CHD risk. CONCLUSION: Distinct SNP clusters appear to impact differentially on remnant particles and LDL. Our findings are consistent with TRL/remnants having a substantially greater atherogenicity per particle than LDL.

Postprandial metabolism of apolipoproteins B48, B100, C-III, and E in humans with APOC3 loss-of-function mutations.

BackgroundApolipoprotein C-III (apoC-III) is a regulator of triglyceride (TG) metabolism, and due to its association with risk of cardiovascular disease, is an emergent target for pharmacological intervention. The impact of substantially lowering apoC-III on lipoprotein metabolism is not clear.MethodsWe investigated the kinetics of apolipoproteins B48 and B100 (apoB48 and apoB100) in chylomicrons, VLDL1, VLDL2, IDL, and LDL in patients heterozygous for a loss-of-function (LOF) mutation in the APOC3 gene. Studies were conducted in the postprandial state to provide a more comprehensive view of the influence of this protein on TG transport.ResultsCompared with non-LOF variant participants, a genetically determined decrease in apoC-III resulted in marked acceleration of lipolysis of TG-rich lipoproteins (TRLs), increased removal of VLDL remnants from the bloodstream, and substantial decrease in circulating levels of VLDL1, VLDL2, and IDL particles. Production rates for apoB48-containing chylomicrons and apoB100-containing VLDL1 and VLDL2 were not different between LOF carriers and noncarriers. Likewise, the rate of production of LDL was not affected by the lower apoC-III level, nor were the concentration and clearance rate of LDL-apoB100.ConclusionThese findings indicate that apoC-III lowering will have a marked effect on TRL and remnant metabolism, with possibly significant consequences for cardiovascular disease prevention.Trial registrationClinicalTrials.gov NCT04209816 and NCT01445730.FundingSwedish Heart-Lung Foundation, Swedish Research Council, ALF grant from the Sahlgrenska University Hospital, Novo Nordisk Foundation, Sigrid Juselius Foundation, Helsinki University Hospital Government Research funds, Finnish Heart Foundation, and Finnish Diabetes Research Foundation.

Role of endogenous incretins in the regulation of postprandial lipoprotein metabolism.

Objective: Incretins are known to influence lipid metabolism in the intestine when administered as pharmacologic agents. The aggregate influence of endogenous incretins on chylomicron production and clearance is less clear, particularly in light of opposing effects of co-secreted hormones. Here, we tested the hypothesis that physiological levels of incretins may impact on production or clearances rates of chylomicrons and VLDL. Design and methods: A group of 22 overweight/obese men was studied to determine associations between plasma levels of glucagon-like peptides 1 and 2 (GLP-1 and GLP-2) and glucose-dependent insulinotropic polypeptide (GIP) after a fat-rich meal and the production and clearance rates of apoB48- and apoB100-containing triglyceride-rich lipoproteins. Subjects were stratified by above- and below-median incretin response (area under the curve). Results: Stratification yielded subgroups that differed about two-fold in incretin response. There were neither differences in apoB48 production rates in chylomicrons or VLDL fractions nor in apoB100 or triglyceride kinetics in VLDL between men with above- vs below-median incretin responses. The men with above-median GLP-1 and GLP-2 responses exhibited higher postprandial plasma and chylomicron triglyceride levels, but this could not be related to altered kinetic parameters. No differences were found between incretin response subgroups and particle clearance rates. Conclusion: We found no evidence for a regulatory effect of endogenous incretins on contemporaneous chylomicron or VLDL metabolism following a standardised fat-rich meal. The actions of incretins at pharmacological doses may not be reflected at physiological levels of these hormones.

Metabolism of triglyceride-rich lipoproteins in health and dyslipidaemia.

Accumulating evidence points to the causal role of triglyceride-rich lipoproteins and their cholesterol-enriched remnants in atherogenesis. Genetic studies in particular have not only revealed a relationship between plasma triglyceride levels and the risk of atherosclerotic cardiovascular disease, but have also identified key proteins responsible for the regulation of triglyceride transport. Kinetic studies in humans using stable isotope tracers have been especially useful in delineating the function of these proteins and revealing the hitherto unappreciated complexity of triglyceride-rich lipoprotein metabolism. Given that triglyceride is an essential energy source for mammals, triglyceride transport is regulated by numerous mechanisms that balance availability with the energy demands of the body. Ongoing investigations are focused on determining the consequences of dysregulation as a result of either dietary imprudence or genetic variation that increases the risk of atherosclerosis and pancreatitis. The identification of molecular control mechanisms involved in triglyceride metabolism has laid the groundwork for a 'precision-medicine' approach to therapy. Novel pharmacological agents under development have specific molecular targets within a regulatory framework, and their deployment heralds a new era in lipid-lowering-mediated prevention of disease. In this Review, we outline what is known about the dysregulation of triglyceride transport in human hypertriglyceridaemia.

Remnants, LDL, and the Quantification of Lipoprotein-Associated Risk in Atherosclerotic Cardiovascular Disease.

PURPOSE OF REVIEW: Implementation of intensive LDL cholesterol (LDL-C) lowering strategies and recognition of the role of triglyceride-rich lipoproteins (TRL) in atherosclerosis has prompted re-evaluation of the suitability of current lipid profile measurements for future clinical practice. RECENT FINDINGS: At low concentrations of LDL-C (< 1.8 mmol/l/70 mg/dl), the Friedewald equation yields estimates with substantial negative bias. New equations provide a more accurate means of calculating LDL-C. Recent reports indicate that the increase in risk per unit increment in TRL/remnant cholesterol may be greater than that of LDL-C. Hence, specific measurement of TRL/remnant cholesterol may be of importance in determining risk. Non-HDL cholesterol and plasma apolipoprotein B have been shown in discordancy analyses to identify individuals at high risk even when LDL-C is low. There is a need to adopt updated methods for determining LDL-C and to develop better biomarkers that more accurately reflect the abundance of TRL remnant particles.

Effects of PNPLA3 I148M on hepatic lipid and very-low-density lipoprotein metabolism in humans.

BACKGROUND: The phospholipase domain-containing 3 gene (PNPLA3)-148M variant is associated with liver steatosis but its influence on the metabolism of triglyceride-rich lipoproteins remains unclear. Here, we investigated the kinetics of large, triglyceride-rich very-low-density lipoprotein (VLDL), (VLDL1 ), and smaller VLDL2 in homozygotes for the PNPLA3-148M variant. METHODS AND RESULTS: The kinetics of apolipoprotein (apo) B100 (apoB100) and triglyceride in VLDL subfractions were analysed in nine subjects homozygous for PNPLA3-148M and nine subjects homozygous for PNPLA3-148I (controls). Liver fat was >3-fold higher in the 148M subjects. Production rates for apoB100 and triglyceride in VLDL1 did not differ significantly between the two groups. Likewise, production rates for VLDL2 -apoB100 and -triglyceride, and fractional clearance rates for both apoB100 and triglyceride in VLDL1 and VLDL2 , were not significantly different. CONCLUSIONS: Despite the higher liver fat content in PNPLA3 148M homozygotes, there was no increase in VLDL production. Equally, VLDL production was maintained at normal levels despite the putative impairment in cytosolic lipid hydrolysis in these subjects.

Triglyceride-rich lipoproteins and their remnants: metabolic insights, role in atherosclerotic cardiovascular disease, and emerging therapeutic strategies-a consensus statement from the European Atherosclerosis Society.

Recent advances in human genetics, together with a large body of epidemiologic, preclinical, and clinical trial results, provide strong support for a causal association between triglycerides (TG), TG-rich lipoproteins (TRL), and TRL remnants, and increased risk of myocardial infarction, ischaemic stroke, and aortic valve stenosis. These data also indicate that TRL and their remnants may contribute significantly to residual cardiovascular risk in patients on optimized low-density lipoprotein (LDL)-lowering therapy. This statement critically appraises current understanding of the structure, function, and metabolism of TRL, and their pathophysiological role in atherosclerotic cardiovascular disease (ASCVD). Key points are (i) a working definition of normo- and hypertriglyceridaemic states and their relation to risk of ASCVD, (ii) a conceptual framework for the generation of remnants due to dysregulation of TRL production, lipolysis, and remodelling, as well as clearance of remnant lipoproteins from the circulation, (iii) the pleiotropic proatherogenic actions of TRL and remnants at the arterial wall, (iv) challenges in defining, quantitating, and assessing the atherogenic properties of remnant particles, and (v) exploration of the relative atherogenicity of TRL and remnants compared to LDL. Assessment of these issues provides a foundation for evaluating approaches to effectively reduce levels of TRL and remnants by targeting either production, lipolysis, or hepatic clearance, or a combination of these mechanisms. This consensus statement updates current understanding in an integrated manner, thereby providing a platform for new therapeutic paradigms targeting TRL and their remnants, with the aim of reducing the risk of ASCVD.

Role of Adenylate Cyclase 9 in the Pharmacogenomic Response to Dalcetrapib: Clinical Paradigm and Molecular Mechanisms in Precision Cardiovascular Medicine.

Following the neutral results of the dal-OUTCOMES trial, a genome-wide study identified the rs1967309 variant in the adenylate cyclase type 9 (ADCY9) gene on chromosome 16 as being associated with the risk of future cardiovascular events only in subjects taking dalcetrapib, a CETP (cholesterol ester transfer protein) modulator. Homozygotes for the minor A allele (AA) were protected from recurrent cardiovascular events when treated with dalcetrapib, while homozygotes for the major G allele (GG) had increased risk. Here, we present the current state of knowledge regarding the impact of rs1967309 in ADCY9 on clinical observations and biomarkers in dalcetrapib trials and the effects of mouse ADCY9 gene inactivation on cardiovascular physiology. Finally, we present our current model of the interaction between dalcetrapib and ADCY9 gene variants in the arterial wall macrophage, based on the intracellular role of CETP in the transfer of complex lipids from endoplasmic reticulum membranes to lipid droplets. Briefly, the concept is that dalcetrapib would inhibit CETP-mediated transfer of cholesteryl esters, resulting in a progressive inhibition of cholesteryl ester synthesis and free cholesterol accumulation in the endoplasmic reticulum. Reduced ADCY9 activity, by paradoxically leading to higher cyclic AMP levels and in turn increased cellular cholesterol efflux, could impart cardiovascular protection in rs1967309 AA patients. The ongoing dal-GenE trial recruited 6145 patients with the protective AA genotype and will provide a definitive answer to whether dalcetrapib will be protective in this population.

Intensive low-density lipoprotein cholesterol lowering in cardiovascular disease prevention: opportunities and challenges.

Elevated levels of low-density lipoprotein cholesterol (LDL-C) are associated with increased risk of coronary heart disease and stroke. Guidelines for the management of dyslipidaemia from the European Society of Cardiology (ESC) and the European Atherosclerosis Society (EAS) were updated in late 2019 in light of recent intervention trials involving the use of innovative lipid-lowering agents in combination with statins. The new guidelines advocate achieving very low LDL-C levels in individuals at highest risk, within the paradigm of 'lower is better'. With the advent of combination therapy using ezetimibe and/or proprotein convertase subtilisin/kexin type 9 inhibitors in addition to statins, the routine attainment of extremely low LDL-C levels in the clinic has become a reality. Moreover, clinical trials in this setting have shown that, over the 5-7 years of treatment experience to date, profound LDL-C lowering leads to further reduction in cardiovascular events compared with more moderate lipid lowering, with no associated safety concerns. These reassuring findings are bolstered by genetic studies showing lifelong very low LDL-C levels (<1.4 mmol/L; <55 mg/dL) are associated with lower cardiovascular risk than in the general population, with no known detrimental health effects. Nevertheless, long-term safety studies are required to consolidate the present evidence base. This review summarises key data supporting the ESC/EAS recommendation to reduce markedly LDL-C levels, with aggressive goals for LDL-C in patients at highest risk, and provides expert opinion on its significance for clinical practice.

Effects of liraglutide on the metabolism of triglyceride-rich lipoproteins in type 2 diabetes.

AIM: To elucidate the impact of liraglutide on the kinetics of apolipoprotein (apo)B48- and apoB100-containing triglyceride-rich lipoproteins in subjects with type 2 diabetes (T2D) after a single fat-rich meal. MATERIALS AND METHODS: Subjects with T2D were included in a study to investigate postprandial apoB48 and apoB100 metabolism before and after 16 weeks on l.8 mg/day liraglutide (n = 14) or placebo (n = 4). Stable isotope tracer and compartmental modelling techniques were used to determine the impact of liraglutide on chylomicron and very low-density lipoprotein (VLDL) production and clearance after a single fat-rich meal. RESULTS: Liraglutide reduced apoB48 synthesis in chylomicrons by 60% (p < .0001) and increased the triglyceride/apoB48 ratio (i.e. the size) of chylomicrons (p < .001). Direct clearance of chylomicrons, a quantitatively significant pathway pretreatment, decreased by 90% on liraglutide (p < .001). Liraglutide also reduced VLDL1 -triglyceride secretion (p = .017) in parallel with reduced liver fat. Chylomicron-apoB48 production and particle size were related to insulin sensitivity (p = .015 and p < .001, respectively), but these associations were perturbed by liraglutide. CONCLUSIONS: In a physiologically relevant setting that mirrored regular feeding in subjects with T2D, liraglutide promoted potentially beneficial changes on postprandial apoB48 metabolism. Using our data in an integrated metabolic model, we describe how the action of liraglutide in T2D on chylomicron and VLDL kinetics could lead to decreased generation of remnant lipoproteins.