👤 E S Stroes

Whether lowering triglyceride-rich lipoproteins and remnant cholesterol favorably modifies coronary atherosclerosis is unclear. Olezarsen, an antisense oligonucleotide that targets apolipoprotein C-III, reduces triglycerides by ~60% and remnant cholesterol by ~70%, has a neutral effect on LDL cholesterol (LDL-C), and reduces apolipoprotein B (apoB) by ~15% in moderate hypertriglyceridemia. We investigated the effect of olezarsen on coronary plaque in adults with largely moderate hypertriglyceridemia. We conducted a coronary computed tomography angiography (CCTA) study within Essence-TIMI 73b, a randomized, placebo-controlled trial of olezarsen vs. placebo that enrolled patients between November 2022 and February 2024. Inclusion criteria were triglycerides ≥150 mg/dL (2.26 mmol/L), presence or high risk for cardiovascular disease, and non-calcified plaque on baseline CCTA. The primary endpoint was percent change from baseline to 12 months in non-calcified plaque volume (NCPV). Of 468 participants (349 olezarsen, 119 placebo), the median age was 63 years (IQR 56-70); 31% were women, and 97% received lipid-lowering therapy. Median baseline triglycerides were 249 mg/dL (IQR 197-331), and remnant cholesterol was 53 mg/dL (IQR 38-76). Median baseline NCPV was 125.3 mm Despite substantial triglyceride and remnant cholesterol lowering, treatment with olezarsen for 12 months on top of standard-of-care lipid-lowering therapy in patients with largely moderate hypertriglyceridemia did not affect noncalcified coronary plaque volume. Show less

Persons with heterozygous familial hypercholesterolemia (HeFH) are at increased risk of atherosclerotic cardiovascular disease due to lifelong elevated levels of low-density lipoprotein cholesterol (LDL-C). Many patients with HeFH do not achieve guideline-recommended LDL-C goals with the currently available lipid-lowering therapies. To evaluate the efficacy of enlicitide decanoate (an oral proprotein convertase subtilisin/kexin type 9 inhibitor) vs placebo in adults with HeFH requiring further lowering of LDL-C levels despite use of statin therapy. This phase 3, randomized clinical trial included persons aged 18 years or older with HeFH currently using lipid-lowering therapy (taking at least a moderate- or high-intensity statin) and either an LDL-C level of 55 mg/dL or greater and a history of major atherosclerotic cardiovascular disease or an LDL-C level of 70 mg/dL or greater without a history of major atherosclerotic cardiovascular disease. The trial was conducted at 59 sites across 17 countries; the first participant was screened on August 8, 2023, and the last follow-up visit occurred on April 7, 2025. Participants were randomized (2:1) to 20 mg of enlicitide (n = 202) or placebo (n = 101) once daily for 52 weeks. The primary outcome was the mean percentage change in LDL-C level at week 24. The secondary outcomes included the mean percentage change in LDL-C level at week 52, the mean percentage change at week 24 in levels of non-high-density lipoprotein cholesterol (non-HDL-C) and apolipoprotein B, and the median percentage change at week 24 in lipoprotein(a). Of the 303 participants (mean age, 52.4 [SD, 13.5] years; 51% were female) randomized, 293 (96.7%) completed the trial. The mean LDL-C level was 119.0 mg/dL (SD, 41.0 mg/dL) at baseline, all had statin current use (81.5% were taking a high-intensity statin), and 64.4% were taking ezetimibe. The mean percentage change in LDL-C level at week 24 was -58.2% in the enlicitide group vs 2.6% in the placebo group (between-group difference, -59.4% [95% CI, -65.6% to -53.2%]; P < .001). The mean percentage change in LDL-C level at week 52 was -55.3% in the enlicitide group vs 8.7% in the placebo group (between-group difference, -61.5% [95% CI, -69.4% to -53.7%]; P < .001). At week 24, the mean percentage change in non-HDL-C level was -52.3% in the enlicitide group vs 2.1% in the placebo group (between-group difference, -53.0% [95% CI, -58.5% to -47.4%]; P < .001), the mean percentage change in apolipoprotein B level was -48.2% vs 1.8%, respectively (between-group difference, -49.1% [95% CI, -54.0% to -44.3%]; P < .001), and the median percentage change in lipoprotein(a) level was -24.7% vs -1.6% (between-group difference, -27.5% [95% CI, -34.3% to -20.6%]; P < .001). The incidence of adverse events, serious adverse events, and study discontinuation due to adverse events was similar between groups. Among adults with HeFH, treatment with enlicitide was well tolerated and significantly reduced levels of LDL-C, apolipoprotein B, non-HDL-C, and lipoprotein(a). ClinicalTrials.gov Identifier: NCT05952869. Show less

Familial chylomicronemia syndrome (FCS) is a rare genetic disorder associated with extreme hypertriglyceridemia and high risk of acute pancreatitis. Olezarsen-an antisense oligonucleotide targeting hepatic apolipoprotein C3 (APOC3) messenger RNA-reduces triglycerides and may decrease pancreatitis risk. Olezarsen 80 mg once monthly is approved in the United States as an adjunct to diet to reduce triglycerides in adults with FCS. To assess the effect of olezarsen on all-cause healthcare resource utilization (HCRU) and overall experience of patients with genetically identified FCS enrolled in the Balance trial (NCT04568434). Prespecified exploratory endpoints included yearly all-cause hospitalization, total inpatient days, and emergency room visits for patients treated with olezarsen (80 or 50 mg) vs placebo, as well as Patient Global Impression of Change (PGIC). Ad hoc outcomes included length of hospital stay, intensive care unit (ICU) admissions, reasons for HCRU, and all-cause HCRU according to patients' history of acute pancreatitis and for individual olezarsen doses vs placebo. Treatment with olezarsen vs placebo for 1 year was associated with an 84% reduction in all-cause hospitalizations (mean rate ratio [95% CI], 0.16 [0.05, 0.50]), 6.3 fewer total inpatient days (95% CI, -11.09, -1.53), better PGIC scores, shorter length of stay, and numerically fewer ICU admissions. Acute pancreatitis was the most frequent cause of hospitalization. Reduction in all-cause inpatient service utilization was consistent for individual dose groups and in patients with a history of acute pancreatitis. In the Balance study, olezarsen reduced all-cause inpatient service utilization and improved the experience of patients with FCS. Show less

Lipoprotein(a) [Lp(a)] is a potent, independent causal risk factor for coronary artery disease (CAD). This study aimed to assess the association between Lp(a) and the diagnosis, clinical presentation, and angiographic characteristics of obstructive CAD and occurrence of myocardial infarction (MI). We included 446 individuals with very high Lp(a) (>230 nmol/L) who underwent routine lipid profiling, matched 2:1 by age and sex using nearest-neighbor propensity matching to 223 controls with low Lp(a) (≤7 nmol/L). Kaplan-Meier analysis was used to assess CAD- and MI-free survival. Multivariable ORs were calculated for multivessel disease and the SYNergy Between percutaneous coronary intervention with TAXus and Cardiac Surgery-1 score. Median follow-up time, defined by age at last follow-up, was 60 years (Q1-Q3: 50-71). Individuals with very high Lp(a) had significantly lower event-free survival time for the diagnosis of obstructive CAD and occurrence of MI (P = 0.006 and P = 0.012, respectively). In multivariable analysis, Lp(a) was associated with multivessel CAD (adjusted OR: 1.43 [per 100 nmol/L]; 95% CI: 1.04-1.96; P = 0.028), but not with an intermediate or high SYNergy Between percutaneous coronary intervention with TAXus and Cardiac Surgery-1 score (adjusted OR: 1.28 [per 100 nmol/L]; 95% CI: 0.82-1.99, P = 0.279). Individuals with very high Lp(a) levels had a 2.4-fold higher risk of ST-segment elevation MI and a 15.9-fold higher risk of recurrent MI compared to those with low Lp(a). Very high Lp(a) is associated with earlier diagnosis of obstructive CAD and MI, predominantly ST-segment elevation MI. In addition, individuals with very high Lp(a) levels seem at a particular high risk of recurrent MI. Show less

Highly effective therapies to reduce triglyceride levels are lacking. Olezarsen is an In this phase 3, international, double-blind, randomized, placebo-controlled trial, we enrolled patients with moderate hypertriglyceridemia (triglyceride level, 150 to 499 mg per deciliter) and elevated cardiovascular risk or with severe hypertriglyceridemia (triglyceride level, ≥500 mg per deciliter) and randomly assigned them in a 1:3 ratio to a 50-mg or 80-mg cohort. The patients were then randomly assigned in a 3:1 ratio to receive monthly subcutaneous olezarsen or matching placebo within each cohort. The primary outcome was the least-squares mean percent change in triglyceride level from baseline to 6 months among the patients with moderate hypertriglyceridemia, reported as the difference between each olezarsen dose group and the placebo group (the placebo-adjusted change). A total of 1349 patients (254 in the olezarsen 50-mg group, 766 in the olezarsen 80-mg group, and 329 in the placebo group) were included in the primary efficacy analysis. The median age was 64 years, 40% of the patients were women, and the median triglyceride level at baseline was 238.5 mg per deciliter (interquartile range, 190.5 to 307.5). At 6 months, the placebo-adjusted least-squares mean change in triglyceride level was -58.4 percentage points (95% confidence interval [CI], -65.1 to -51.7; P<0.001) in the olezarsen 50-mg group and -60.6 percentage points (95% CI, -67.1 to -54.0; P<0.001) in the olezarsen 80-mg group. The incidence of serious adverse events appeared to be similar across the trial groups. Among patients with moderate hypertriglyceridemia and elevated cardiovascular risk, treatment with olezarsen resulted in significantly greater reduction in triglyceride levels at 6 months than placebo. (Funded by Ionis Pharmaceuticals; ESSENCE-TIMI 73b ClinicalTrials.gov number, NCT05610280.). Show less

Cost-effectiveness of Lipoprotein(a) [Lp(a)] testing is not established. We aimed to evaluate the cost-effectiveness of Lp(a) testing in the cardiovascular disease (CVD) primary prevention population from healthcare and societal perspectives. We constructed and validated a multi-state microsimulation Markov model for a population of 10,000 individuals aged between 40 and 69 years without CVD, selected randomly from the UK Biobank. The model evaluated Lp(a) testing in individuals not initially classified as high-risk based on age, diabetes status, or the SCORE-2 algorithm. Those with an Lp(a) level ≥105 nmol/L (50 mg/dL) were treated as high risk (initiation of a statin plus blood pressure lowering). The Lp(a) testing intervention was compared to standard of care. The primary analyses were conducted from the Australian and UK healthcare perspectives in 2023AUD/GBP. A cost adaptation method estimated cost-effectiveness in multiple European countries, Canada, and the USA. Among 10,000 individuals, 1,807 had their treatment modified from Lp(a) testing. This led to 217 and 255 quality-adjusted life years gained in Australia and the UK, respectively, with corresponding incremental cost-effectiveness ratios of 12,134 (cost-effective) and -3,491 (cost-saving). From a societal perspective, Lp(a) testing saved $85 and £263 per person in Australia and the UK, respectively. Lp(a) testing was cost-saving among all countries tested in the cost adaptation analysis. Lp(a) testing in the primary prevention population to reclassify CVD risk and treatment is cost-saving and warranted to prevent CVD. Show less

High plasma lipoprotein(a) [Lp(a)] levels are associated with accelerated atherosclerosis and subsequent atherosclerotic cardiovascular disease (ASCVD), potentially through enhanced inflammatory signaling of monocytes. Given that monocytes are major players in ASCVD risk and the role of epigenetic changes in regulating their responsiveness, we propose that investigating changes in chromatin accessibility could reveal the underlying mechanisms of enhanced monocyte inflammation. In this observational case-control study, we collected blood from subjects with low (<25 nmol/L) and elevated (>350 nmol/L) plasma Lp(a) with and without a history of ASCVD, matched for age and sex. A total of 60 subjects were included in the study, comprising 60% males and a mean age of 62.8 ± 7.8 years. We assessed gene expression and chromatin accessibility of fluorescence-activated cell sorting (FACS)-sorted classical monocytes using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and bulk assay for transposase-accessible chromatin (ATAC)-sequencing and analyzed plasma cytokine levels. Subjects with high plasma Lp(a) showed significantly increased gene expression of IFIT3. At the plasma level, subjects with high Lp(a) without ASCVD were distinguished by higher concentrations of chemokine C-X-C motif ligand 10 (CXCL10). While these results are consistent with previous research demonstrating increased interferon-γ signaling in monocytes of individuals with elevated Lp(a), we did not detect differences in chromatin accessibility of monocytes between subjects with high or low Lp(a), irrespective of ASCVD status. While subjects with high Lp(a) levels showed enhanced monocyte inflammation, no differences in chromatin accessibility were detected. This suggests that the pro-inflammatory signature of Lp(a) and ASCVD on monocytes is regulated at a level other than chromatin accessibility. Show less

Lipoprotein lipase (LPL) deficiency, a rare inherited metabolic disorder, is characterized by high triglyceride (TG) levels and life-threatening acute pancreatitis. Current treatment for pediatric patients involves a lifelong severely fat-restricted diet, posing adherence challenges. Volanesorsen, an EMA-approved RNA therapy for adults, effectively reduces TG levels by decreasing the production of apolipoprotein C-III. This 96-week observational open-label study explores Volanesorsen's safety and efficacy in a 13-year-old female with LPL deficiency. The patient, with a history of severe TG elevations, 53 hospital admissions, and life-threatening recurrent pancreatitis despite dietary restrictions, received weekly subcutaneous Volanesorsen injections. We designed a protocol for this investigator-initiated study, primarily focusing on changes in fasting TG levels and hospital admissions. While the injections caused occasional pain and swelling, no other adverse events were observed. TG levels decreased during treatment, with more measurements below the pancreatitis risk threshold compared to pre-treatment. No hospital admissions occurred in the initial 14 months of treatment, contrasting with 21 admissions in the 96 weeks before. In the past 10 months, two pancreatitis episodes may have been linked to dietary noncompliance. Dietary restrictions were relaxed, increasing fat intake by 65% compared to baseline. While not fully reflected in the PedsQL, both parents and the patient narratively reported an improved quality of life. This study demonstrates, for the first time, that Volanesorsen is tolerated in a pediatric patient with severe LPL deficiency and effectively lowers TG levels, preventing life-threatening complications. This warrants consideration for expanded access in this population. Show less

Triglyceride-rich lipoproteins (TRLs) are a source of residual risk in patients with atherosclerotic cardiovascular disease, and are indirectly correlated with triglyceride (TG) levels. Previous clinical trials studying TG-lowering therapies have either failed to reduce major adverse cardiovascular events or shown no linkage of TG reduction with event reduction, particularly when these agents were tested on a background of statin therapy. Limitations in trial design may explain this lack of efficacy. With the advent of new RNA-silencing therapies in the TG metabolism pathway, there is renewed focus on reducing TRLs for major adverse cardiovascular event reduction. In this context, the pathophysiology of TRLs, pharmacological effects of TRL-lowering therapies, and optimal design of cardiovascular outcomes trials are major considerations. Show less

The importance of protein glycosylation in regulating lipid metabolism is becoming increasingly apparent. We set out to further investigate this by studying the effects of defective glycosylation on plasma lipids in patients with B4GALT1-CDG, caused by a mutation in B4GALT1 with defective N-linked glycosylation. We studied plasma lipids, cholesteryl ester transfer protein (CETP) glyco-isoforms with isoelectric focusing followed by a western blot and CETP activity in three known B4GALT1-CDG patients and compared them with 11 age- and gender-matched, healthy controls. B4GALT1-CDG patients have significantly lowered non-high density lipoprotein cholesterol (HDL-c) and total cholesterol to HDL-c ratio compared with controls and larger HDL particles. Plasma CETP was hypoglycosylated and less active in B4GALT1-CDG patients compared to matched controls. Our study provides insight into the role of protein glycosylation in human lipoprotein homeostasis. The hypogalactosylated, hypo-active CETP found in patients with B4GALT1-CDG indicates a role of protein galactosylation in regulating plasma HDL and LDL. Patients with B4GALT1-CDG have large HDL particles probably due to hypogalactosylated, hypo-active CETP. Show less

Evidence on the causal link between plasma triglyceride (TG) levels and risk for cardiovascular disease (CVD) has recently emerged. Individuals with the metabolic syndrome have an increased risk for acquiring elevated TG levels later in life. Moreover, common DNA sequence variations in genes affecting TG levels identify individuals at risk for elevated plasma TG levels. We evaluated whether a 3-single nucleotide polymorphism (SNP) TG gene risk score (GRS) and a metabolic risk score (MetRS) both improved CVD risk prediction. A 3-SNP GRS and MetRS were generated in the EPIC-Norfolk cohort (n = 20,074) based on 3 SNPs in LPL and APOA5 or the number of Metabolic Syndrome criteria present (maximum 5), respectively. The associations between the 3-SNP GRS, MetRS, TG levels, and CVD risk were evaluated. The 3-SNP GRS and MetRS were both linearly associated with plasma TG levels, that is, +0.25 mmol/L [95% CI 0.22-0.27] per allele change (P < .001) and +0.72 mmol/L [95% CI 0.70-0.73] per increase of number of metabolic syndrome risk score points (P < .001), respectively. We observed a positive association between the 3-SNP GRS and the risk of CVD with an adjusted hazard ratio (HR) of 1.35 [95% CI 1.04-1.74] for the highest versus the lowest GRS, which was independent of the MetRS. For the MetRS, the adjusted HR was 2.03 [95% CI 1.73-2.40] for the highest versus the lowest MetRS. Both the 3-SNP GRS and the MetRS are associated with increased plasma TG levels and increased risk for CVD. Show less

Familial chylomicronemia syndrome is a rare genetic disorder that is caused by loss of lipoprotein lipase activity and characterized by chylomicronemia and recurrent episodes of pancreatitis. There are no effective therapies. In an open-label study of three patients with this syndrome, antisense-mediated inhibition of hepatic We conducted a phase 3, double-blind, randomized 52-week trial to evaluate the safety and effectiveness of volanesorsen in 66 patients with familial chylomicronemia syndrome. Patients were randomly assigned, in a 1:1 ratio, to receive volanesorsen or placebo. The primary end point was the percentage change in fasting triglyceride levels from baseline to 3 months. Patients receiving volanesorsen had a decrease in mean plasma apolipoprotein C-III levels from baseline of 25.7 mg per deciliter, corresponding to an 84% decrease at 3 months, whereas patients receiving placebo had an increase in mean plasma apolipoprotein C-III levels from baseline of 1.9 mg per deciliter, corresponding to a 6.1% increase (P<0.001). Patients receiving volanesorsen had a 77% decrease in mean triglyceride levels, corresponding to a mean decrease of 1712 mg per deciliter (19.3 mmol per liter) (95% confidence interval [CI], 1330 to 2094 mg per deciliter [15.0 to 23.6 mmol per liter]), whereas patients receiving placebo had an 18% increase in mean triglyceride levels, corresponding to an increase of 92.0 mg per deciliter (1.0 mmol per liter) (95% CI, -301.0 to 486 mg per deciliter [-3.4 to 5.5 mmol per liter]) (P<0.001). At 3 months, 77% of the patients in the volanesorsen group, as compared with 10% of patients in the placebo group, had triglyceride levels of less than 750 mg per deciliter (8.5 mmol per liter). A total of 20 of 33 patients who received volanesorsen had injection-site reactions, whereas none of the patients who received placebo had such reactions. No patients in the placebo group had platelet counts below 100,000 per microliter, whereas 15 of 33 patients in the volanesorsen group had such levels, including 2 who had levels below 25,000 per microliter. No patient had platelet counts below 50,000 per microliter after enhanced platelet-monitoring began. Volanesorsen lowered triglyceride levels to less than 750 mg per deciliter in 77% of patients with familial chylomicronemia syndrome. Thrombocytopenia and injection-site reactions were common adverse events. (Funded by Ionis Pharmaceuticals and Akcea Therapeutics; APPROACH Clinical Trials.gov number, NCT02211209.). Show less

Familial chylomicronemia syndrome (FCS) is an ultra-rare phenotype that is usually caused by biallelic mutations in the LPL gene encoding lipoprotein lipase, or less often in APOC2, APOA5, LMF1, or GPIHBP1 genes encoding cofactors or interacting proteins. We evaluated baseline phenotypes among FCS participants in a phase 3 randomized placebo-controlled trial of volanesorsen (NCT02211209). Baseline clinical, fasting, and postfat load metabolic markers were assessed. Targeted next-generation DNA sequencing plus custom bioinformatics was used to genotype subjects. Among 52 FCS individuals, 41 had biallelic LPL gene mutations (LPL-FCS patients): 82%, 7%, and 11% were missense, nonsense, and splicing variants, respectively. Eleven individuals had non-LPL-FCS; 2 had mutations in APOA5, 5 in GPIHBP1, and 1 each in LMF1 and APOC2 genes, respectively. Two other individuals were double heterozygotes, each with 1 normal LPL allele. All subjects had extremely high triglycerides (TGs) and chylomicrons, but very low levels of other lipoproteins. Compared with LPL-FCS individuals, non-LPL-FCS individuals were very similar for most traits, but had significantly higher postheparin LPL activity, higher 4-hour postprandial insulin and C-peptide levels; and higher low-density lipoprotein cholesterol levels. In non-LPL-FCS individuals compared to those with LPL-FCS, there were also nonsignificant trends toward lower levels of total and chylomicron TGs, lower 4-hour postprandial chylomicron TG levels, and higher very-low-density lipoprotein TG levels. Thus, LPL FCS and non-LPL FCS are largely phenotypically similar. However, LPL FCS patients have lower postheparin LPL activity and a trend toward higher TGs, whereas low-density lipoprotein cholesterol was higher in non-LPL-FCS patients. Show less

A large proportion of patients with heterozygous familial hypercholesterolemia (heFH) do not reach low-density lipoprotein cholesterol (LDL-c) levels advocated by international guidelines (<70 mg/dL or <100 mg/dL). We set out to model which proportion of patients reach targets using conventional and novel therapies. We performed a cross-sectional analysis in a large cohort of genetically identified heFH patients and calculated the proportion reaching treatment targets in four scenarios: (1) after 50% LDL-c reduction (representing maximal dose statin); (2) after 70% LDL-c reduction (maximal dose statin + ezetimibe); (3) additional 40% LDL-c reduction representing cholesteryl ester transfer protein inhibitor (CETPi); and (4) 60% LDL-c reduction (proprotein convertase subtilisin/kexin type 9 inhibitors [PCSK9i]), on top of scenario 2. We applied 100% adherence rates and literature-based adherence rates from 62% to 80%. We included 1,059 heFH patients with and 9,420 heFH patients without coronary heart disease (CHD). With maximal dose statin, 8.3% and 48.1% of patients with and without CHD would reach their recommended LDL-c targets, respectively. This increases to 54.3% and 93.2% when ezetimibe is added. Addition of CETPi increases these numbers to 95.7% and 99.7%, whereas adding PCSK9i would result in 99.8% and 100% goal attainment. Using literature-based adherence rates, these numbers decrease to 3.8% and 27.3% for maximal dose statin, 5.8% and 38.9% combined with ezetimibe, 31.4% and 81.2% when adding CETPi, and 40.3% and 87.1% for addition of PCSK9i. Less than 10% with and 50% of heFH patients without CHD would reach treatment targets with maximal dose statin, but this substantially increases on addition of ezetimibe, CETPi, or PCSK9i. However, considering recently published adherence data, this might be lower in real life, especially in heFH patients with CHD. Show less

Elevated nonfasting TG-rich lipoprotein levels are a risk factor for CVD. To further evaluate the relevance of LDL-receptor (LDLr) pathway and heparan sulfate proteoglycans (HSPGs) in TG homeostasis, we analyzed fasting and postprandial TG levels in mice bearing combined heterozygous mutations in both Exostosin (Ext) 1 and Ldlr, in subjects with hereditary multiple exostosis (HME) due to a heterozygous loss-of-function mutation in EXT1 or EXT2 (N = 13), and in patients with heterozygous mutations in LDLR [familial hypercholesterolemia (FH)] and SNPs in major HSPG-related genes (n = 22). Mice bearing a homozygous mutation in hepatic Ext1 exhibited elevated plasma TGs similar to mice lacking other key enzymes involved in HSPG assembly. Compound heterozygous mice lacking Ldlr and Ext1 showed synergy on plasma TG accumulation and postprandial clearance. In human subjects, a trend was observed in HME patients toward reduced postprandial TG clearance with a concomitant reduction in chylomicron clearance [area under the curve (AUC)-retinyl ester (RE) HME, 844 ± 127 vs. controls, 646 ± 119 nM/h, P = 0.09]. Moreover, in FH subjects with a high HSPG gene score, retinyl palmitate excursions were higher (AUC-RE, 2,377 ± 293 vs. 1,565 ± 181 nM/h, P < 0.05). Incremental AUC-apoB48 was similar between the groups. In conclusion, the data are supportive for a minor yet additive role of HSPG in human postprandial TG clearance, and further studies are warranted. Show less

Apolipoprotein C3 (APOC3) mutations carriers typically display high plasma high-density lipoprotein cholesterol (HDL-C) and low triglycerides (TGs). We set out to investigate the prevalence and clinical consequences of APOC3 mutations in individuals with hyperalphalipoproteinemia. Two novel mutations (c.-13-2A>G and c.55+1G>A) and one known mutation (c.127G>A;p.Ala43Thr) were found. Lipid profiles and apoCIII isoform distributions were measured. c.55+1G>A mutation carriers displayed higher HDL-C percentiles (35.6 ± 35.8 vs 99.0 ± 0, p = 0.002) and lower TGs (0.51 (0.37-0.61) vs 1.42 (1.12-1.81) mmol/l, p = 0.007) and apoCIII levels (4.24 ± 1.57 vs 7.33 ± 3.61 mg/dl, p = 0.18). c.-13-2A>G mutation carriers did not display significantly different HDL-C levels (84.0 ± 30.0 vs 63.7 ± 45.7, p = 0.50), a trend towards lower TGs [0.71 (0.54 to 0.78) vs 0.85 (0.85 to -) mmol/l, p = 0.06] and significantly lower apoCIII levels (3.09 ± 1.08 vs 11.45 ± 1.06 mg/dl, p = 0.003). p.Ala43Thr mutation carriers displayed a trend towards higher HDL-C percentiles (91.2 ± 31.8 vs 41.0 ± 29.7 mmol/l, p = 0.06) and significantly lower TGs [0.58 (0.36-0.63) vs 0.95 (0.71-1.20) mmol/l, p = 0.02] and apoCIII levels (4.92 ± 2.33 vs 6.60 ± 1.60, p = 0.25). Heterozygosity for APOC3 mutations results in high HDL-C and low TGs and apoCIII levels. This favourable lipid profile in patients with genetically low apoCIII levels holds promise for current studies investigating the potential of apoCIII inhibition as a novel therapeutic in cardiovascular disease prevention. Show less

Exotosin (EXT) proteins are involved in the chain elongation step of heparan sulfate (HS) biosynthesis, which is intricately involved in organ development. Loss of function mutations (LOF) in EXT1 and EXT2 result in hereditary exostoses (HME). Interestingly, HS plays a role in pancreas development and beta-cell function, and genetic variations in EXT2 are associated with an increased risk for type 2 diabetes mellitus. We hypothesized that loss of function of EXT1 or EXT2 in subjects with hereditary multiple exostoses (HME) affects pancreatic insulin secretion capacity and development. We performed an oral glucose tolerance test (OGTT) followed by hyperglycemic clamps to investigate first-phase glucose-stimulated insulin secretion (GSIS) in HME patients and age and gender matched non-affected relatives. Pancreas volume was assessed with magnetic resonance imaging (MRI). OGTT did not reveal significant differences in glucose disposal, but there was a markedly lower GSIS in HME subjects during hyperglycemic clamp (iAUC HME: 0.72 [0.46-1.16] vs. controls 1.53 [0.69-3.36] nmol·l-1·min-1, p<0.05). Maximal insulin response following arginine challenge was also significantly attenuated (iAUC HME: 7.14 [4.22-10.5] vs. controls 10.2 [7.91-12.70] nmol·l-1·min-1 p<0.05), indicative of an impaired beta-cell reserve. MRI revealed a significantly smaller pancreatic volume in HME subjects (HME: 72.0±15.8 vs. controls 96.5±26.0 cm3 p = 0.04). In conclusion, loss of function of EXT proteins may affect beta-cell mass and insulin secretion capacity in humans, and render subjects at a higher risk of developing type 2 diabetes when exposed to environmental risk factors. Show less

Heparanase is the major enzyme involved in degradation of endothelial heparan sulfates, which is associated with impaired endothelial nitric oxide synthesis. However, the effect of heparan sulfate chain length in relation to endothelial function and nitric oxide availability has never been investigated. We studied the effect of heterozygous mutations in heparan sulfate elongation genes EXT1 and EXT2 on endothelial function in vitro as well as in vivo. Flow-mediated dilation, a marker of nitric oxide bioavailability, was studied in Ext1(+/-) and Ext2(+/-) mice versus controls (n=7 per group), as well as in human subjects with heterozygous loss of function mutations in EXT1 and EXT2 (n=13 hereditary multiple exostoses and n=13 controls). Endothelial function was measured in microvascular endothelial cells under laminar flow with or without siRNA targeting EXT1 or EXT2. Endothelial glycocalyx and maximal arteriolar dilatation were significantly altered in Ext1(+/-) and Ext2(+/-) mice compared to wild-type littermates (glycocalyx: wild-type 0.67±0.1 μm, Ext1(+/-) 0.28±0.1 μm and Ext2(+/-) 0.25±0.1 μm, P<0.01, maximal arteriolar dilation during reperfusion: wild-type 11.3±1.0%), Ext1(+/-) 15.2±1.4% and Ext2(+/-) 13.8±1.6% P<0.05). In humans, brachial artery flow-mediated dilation was significantly increased in hereditary multiple exostoses patients (hereditary multiple exostoses 8.1±0.8% versus control 5.6±0.7%, P<0.05). In line, silencing of microvascular endothelial cell EXT1 and EXT2 under flow led to significant upregulation of endothelial nitric oxide synthesis and phospho-endothelial nitric oxide synthesis protein expression. Our data implicate that heparan sulfate elongation genes EXT1 and EXT2 are involved in maintaining endothelial homeostasis, presumably via increased nitric oxide bioavailability. Show less

The severe forms of hypertriglyceridaemia (HTG) are caused by mutations in genes that lead to the loss of function of lipoprotein lipase (LPL). In most patients with severe HTG (TG > 10 mmol L(-1) ), it is a challenge to define the underlying cause. We investigated the molecular basis of severe HTG in patients referred to the Lipid Clinic at the Academic Medical Center Amsterdam. The coding regions of LPL, APOC2, APOA5 and two novel genes, lipase maturation factor 1 (LMF1) and GPI-anchored high-density lipoprotein (HDL)-binding protein 1 (GPIHBP1), were sequenced in 86 patients with type 1 and type 5 HTG and 327 controls. In 46 patients (54%), rare DNA sequence variants were identified, comprising variants in LPL (n = 19), APOC2 (n = 1), APOA5 (n = 2), GPIHBP1 (n = 3) and LMF1 (n = 8). In 22 patients (26%), only common variants in LPL (p.Asp36Asn, p.Asn318Ser and p.Ser474Ter) and APOA5 (p.Ser19Trp) could be identified, whereas no mutations were found in 18 patients (21%). In vitro validation revealed that the mutations in LMF1 were not associated with compromised LPL function. Consistent with this, five of the eight LMF1 variants were also found in controls and therefore cannot account for the observed phenotype. The prevalence of mutations in LPL was 34% and mostly restricted to patients with type 1 HTG. Mutations in GPIHBP1 (n = 3), APOC2 (n = 1) and APOA5 (n = 2) were rare but the associated clinical phenotype was severe. Routine sequencing of candidate genes in severe HTG has improved our understanding of the molecular basis of this phenotype associated with acute pancreatitis and may help to guide future individualized therapeutic strategies. Show less