apoC-III Levels Research Articles

Identification of biomarker panels as predictors of severity in coronary artery disease.

Matrix metalloproteinases (MMPs) are implicated in atherosclerotic plaque rupture and recondition. Specific tissue inhibitors (TIMPs) control MMP functions. Both MMPs and TIMPs are potential biomarkers of plaque instability. Elevated Apo‐CII and CIII and Apo‐E levels are recognized as cardiovascular disease risk factors. We aimed to establish the best blood biomarker panel to evaluate the coronary artery disease (CAD) severity. Plasma levels of MMP‐3 and MMP‐9, TIMP‐1 and TIMP‐2, Apo‐CII, Apo‐CIII and Apo‐E were measured in 472 patients with CAD evaluated by coronary angiography and electrocardiography, and in 285 healthy controls. MMP‐3 and MMP‐9 plasma levels in CAD patients were significantly increased (P < 0.001) compared to controls (3.54‐ and 3.81‐fold, respectively). Furthermore, these increments are modulated by CAD severity as well as for Apo‐CII and Apo‐CIII levels (P < 0.001). TIMPs levels were decreased in CAD versus controls (P < 0.001) and in inverse correlation to MMPs. Standard ROC curve approach showed the importance of panels of biomarkers, including MMP‐3, MMP‐9, TIMP‐1, TIMP‐2, Apo‐CII and Apo‐CIII, for disease aggravation diagnosis. A high area under curve (AUC) value (0.995) was reached for the association of MMP‐9, TIMP‐2 and Apo‐CIII. The unbalance between MMPs and TIMPs in vascular wall and dyslipidaemia creates favourable conditions for plaque disruption. Our study suggests that the combination of MMP‐9, TIMP‐2 and Apo‐CIII values (‘CAD aggravation panel’) characterizes the severity of CAD, that is electrophysiological state, number of involved vessels, stent disposal and type of stent.

Apolipoprotein C-II and C-III preferably transfer to both high-density lipoprotein (HDL)2 and the larger HDL3 from very low-density lipoprotein (VLDL).

Triglyceride hydrolysis by lipoprotein lipase (LPL), regulated by apolipoproteins C-II (apoC-II) and C-III (apoC-III), is essential for maintaining normal lipid homeostasis. During triglyceride lipolysis, the apoCs are known to be transferred from very low-density lipoprotein (VLDL) to high-density lipoprotein (HDL), but the detailed mechanisms of this transfer remain unclear. In this study, we investigated the extent of the apoC transfers and their distribution in HDL subfractions, HDL2 and HDL3. Each HDL subfraction was incubated with VLDL or biotin-labeled VLDL, and apolipoproteins and lipids in the re-isolated HDL were quantified using western blotting and high-performance liquid chromatography (HPLC). In consequence, incubation with VLDL showed the increase of net amount of apoC-II and apoC-III in the HDL. HPLC analysis revealed that the biotin-labeled apolipoproteins, including apoCs and apolipoprotein E, were preferably transferred to the larger HDL3. No effect of cholesteryl ester transfer protein inhibitor on the apoC transfers was observed. Quantification of apoCs levels in HDL2 and HDL3 from healthy subjects (n = 8) showed large individual differences between apoC-II and apoC-III levels. These results suggest that both apoC-II and apoC-III transfer disproportionately from VLDL to HDL2 and the larger HDL3, and these transfers might be involved in individual triglyceride metabolism.

Higher ANGPTL3 and APO CIII levels are associated with APO B48 (chylomicron remnant) dyslipidemia and visceral fat in obese adolescents

Background and Aims: The role of triglyceride-rich lipoprotein remnants (IDL and chylomicron remnants) in atherosclerosis residual risk is uncontroversial. Albeit, data on adolescents is scarce especially with regards to apoB48 lipoproteins such as chylomicron remnants. We hypothesized that obese adolescents have higher remnant B48 levels associated with lipoprotein lipase dysregulation.

The dual glucose-dependent insulinotropic peptide and glucagon-like peptide-1 receptor agonist, tirzepatide, improves lipoprotein biomarkers associated with insulin resistance and cardiovascular risk in patients with type 2 diabetes.

AimTo better understand the marked decrease in serum triglycerides observed with tirzepatide in patients with type 2 diabetes, additional lipoprotein‐related biomarkers were measured post hoc in available samples from the same study.Materials and MethodsPatients were randomized to receive once‐weekly subcutaneous tirzepatide (1, 5, 10 or 15 mg), dulaglutide (1.5 mg) or placebo. Serum lipoprotein profile, apolipoprotein (apo) A‐I, B and C‐III and preheparin lipoprotein lipase (LPL) were measured at baseline and at 4, 12 and 26 weeks. Lipoprotein particle profile by nuclear magnetic resonance was assessed at baseline and 26 weeks. The lipoprotein insulin resistance (LPIR) score was calculated.ResultsAt 26 weeks, tirzepatide dose‐dependently decreased apoB and apoC‐III levels, and increased serum preheparin LPL compared with placebo. Tirzepatide 10 and 15 mg decreased large triglyceride‐rich lipoprotein particles (TRLP), small low‐density lipoprotein particles (LDLP) and LPIR score compared with both placebo and dulaglutide. Treatment with dulaglutide also reduced apoB and apoC‐III levels but had no effect on either serum LPL or large TRLP, small LDLP and LPIR score. The number of total LDLP was also decreased with tirzepatide 10 and 15 mg compared with placebo. A greater reduction in apoC‐III with tirzepatide was observed in patients with high compared with normal baseline triglycerides. At 26 weeks, change in apoC‐III, but not body weight, was the best predictor of changes in triglycerides with tirzepatide, explaining up to 22.9% of their variability.ConclusionsTirzepatide treatment dose‐dependently decreased levels of apoC‐III and apoB and the number of large TRLP and small LDLP, suggesting a net improvement in atherogenic lipoprotein profile.

Urinary Apolipoprotein C3 Is a Potential Biomarker for Alzheimer’s Disease

Introduction: Biomarkers of Alzheimer’s disease (AD) that can easily be measured in routine health checkups are desirable. Urine is a source of biomarkers that can be collected easily and noninvasively. We previously reported on the comprehensive profile of the urinary proteome of AD patients and identified proteins estimated to be significantly increased or decreased in AD patients by a label-free quantification method. The present study aimed to validate urinary levels of proteins that significantly differed between AD and control samples from our proteomics study (i.e., apolipoprotein C3 [ApoC3], insulin-like growth factor-binding protein 3 [Igfbp3], and apolipoprotein D [ApoD]). Methods: Enzyme-linked immunosorbent assays (ELISAs) were performed using urine samples from the same patient and control groups analyzed in the previous proteomics study (18 AD and 18 controls, set 1) and urine samples from an independent group of AD patients and controls (13 AD, 5 mild cognitive impairment [MCI], and 32 controls) from the National Center for Geriatrics and Gerontology Biobank (set 2). Results: In set 1, the crude urinary levels of ApoD, Igfbp3, and creatinine-adjusted ApoD were significantly higher in the AD group relative to the control group (p = 0.003, p = 0.002, and p = 0.019, respectively), consistent with our previous proteomics results. In set 2, however, the crude urinary levels of Igfbp3 were significantly lower in the AD+MCI group than in the control group (p = 0.028), and the levels of ApoD and ApoC3 did not differ significantly compared to the control group. Combined analysis of all samples revealed creatinine-adjusted ApoC3 levels to be significantly higher in the AD+MCI group (p = 0.015) and the AD-only group (p = 0.011) relative to the control group. Conclusion: ApoC3 may be a potential biomarker for AD, as validated by ELISA. Further analysis of ApoC3 as a urinary biomarker for AD is warranted.

High density lipoprotein cholesterol and apolipoprotein A-I are associated with greater cerebral perfusion in multiple sclerosis

BackgroundThe pathophysiological mechanisms underlying the associations of multiple sclerosis (MS) neurodegeneration serum cholesterol profiles is currently unknown. ObjectiveTo determine associations between lipid profile measures and cerebral perfusion-based indices in MS patients. MethodsSeventy-seven MS patients underwent 3 T MRI. Cerebral blood volume (CBV), time-to-peak (TTP) and mean transit time (MTT) measures were computed from dynamic susceptibility contrast (DSC) perfusion-weighted imaging (PWI) for normal-appearing brain tissue (NABT), GM, cortex, deep gray matter (DGM) and thalamus. Total cholesterol, low and high-density lipoprotein cholesterol (LDL-C and HDL-C) and the apolipoproteins (Apo), ApoA-I, ApoA-II, ApoB, ApoC-II and ApoE levels were measured in plasma. Age and body mass index (BMI)-adjusted correlations were used to assess the associations between PWI and lipid profile measures. ResultsHigher HDL-C levels were associated with shorter MTT, which are indicative of greater perfusion, in NABT (p = 0.012), NAWM (p = 0.021), GM (p = 0.009), cortex (p = 0.014), DGM p = 0.015; and thalamus p = 0.015). The HDL-C-associated apolipoproteins, ApoA-I and ApoA-II, were associated with shorter MTT of the same brain regions (all p < 0.028). HDL-C and ApoA-I levels were also associated with shorter TTP, indicative of faster cerebral blood delivery. ApoC-II was associated with lower nCBV of the GM and cortex (p = 0.035 and p = 0.014, respectively). ConclusionThe HDL pathway is associated with better global brain perfusion and faster cerebral blood delivery as measured by shorter MTT and TTP, respectively. ApoC-II may be associated with lower cortical and DGM perfusion.

Prognostic utility of triglyceride-rich lipoprotein-related markers in patients with coronary artery disease

TG-rich lipoprotein (TRL)-related biomarkers, including TRL-cholesterol (TRL-C), remnant-like lipoprotein particle-cholesterol (RLP-C), and apoC-III have been associated with atherosclerosis. However, their prognostic values have not been fully determined, especially in patients with previous CAD. This study aimed to examine the associations of TRL-C, RLP-C, and apoC-III with incident cardiovascular events (CVEs) in the setting of secondary prevention of CAD. Plasma TRL-C, RLP-C, and total apoC-III were directly measured. A total of 4,355 participants with angiographically confirmed CAD were followed up for the occurrence of CVEs. During a median follow-up period of 5.1 years (interquartile range: 3.9-6.4 years), 543 (12.5%) events occurred. Patients with incident CVEs had significantly higher levels of TRL-C, RLP-C, and apoC-III than those without events. Multivariable Cox analysis indicated that a log unit increase in TRL-C, RLP-C, and apoC-III increased the risk of CVEs by 49% (95% CI: 1.16-1.93), 21% (95% CI: 1.09-1.35), and 40% (95% CI: 1.11-1.77), respectively. High TRL-C, RLP-C, and apoC-III were also independent predictors of CVEs in individuals with LDL-C levels ≤1.8 mmol/l (n = 1,068). The addition of RLP-C level to a prediction model resulted in a significant increase in discrimination, and all three TRL biomarkers improved risk reclassification. Thus, TRL-C, RLP-C, and apoC-III levels were independently associated with incident CVEs in Chinese CAD patients undergoing statin therapy.

Apolipoprotein CIII Deficiency Protects Against Atherosclerosis in Knockout Rabbits.

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

BAL and serum multiplex lipid profiling in idiopathic pulmonary fibrosis and fibrotic hypersensitivity pneumonitis

BackgroundDifferential diagnosis between IPF and fibrotic HP (fHP) can be challenging: these two ILDs share many common features but call for different therapeutic approaches. In the present study, differential lipid mediator profiles were analysed by a new method in BAL and serum from HP and IPF patients. Materials and methods76 patients were enrolled retrospectively in the study. Median age (IQR) was 67 years (51–74); 63% were males, 30 had fHP and 46 had IPF. Serum and BAL samples were collected at initial diagnosis. For quantification of serum and BAL lipid mediators was used bead-based multiplex LEGENDPlex™ analysis (Biolegend). ResultsSerum Apo A1 levels were significantly higher in IPF than fHP patients (p = 0.314); indeed, serum levels of CCL2 and Apo C3 were lower in HP than in IPF patients (p = 0.013 and p = 0.041, respectively). BAL concentrations of Apo A1, adipsin, Apo C3 and APN were significantly lower in IPF than in fHP patients (p < 0.0001, p < 0.0001, p = 0.007 and p = 0.023, respectively). In the logistic regression, IPF was tested as dependent variable. Serum levels of Apo A1, CCL2 and Apo C3 were tested as independent variables and ROC curve analysis of model performance showed AUC 93% (p < 0.0001); on the other hand, BAL concentrations of Apo A1, adipsin, Apo C3 and APN showed AUC 81% (p < 0.0001). DiscussionLipid biomarkers evaluated in BAL in our study confirm the hypothesis that fHP and IPF have different lung fibrosis phenotypes. The former is a post-inflammatory cell-regulated ILD and the second is more related to tissue remodeling and repair.

Metabolic characterisation of disturbances in the APOC3/triglyceride-rich lipoprotein pathway through sample-based recall by genotype

IntroductionHigh plasma triacylglyceride levels are known to be associated with increased risk of atherosclerotic cardiovascular disease. Apolipoprotein C-III (apoC-III) is a key regulator of plasma triacylglyceride levels and is associated with hypertriglyceridemia via a number of pathways. There is consistent evidence for an association of cardiovascular events with blood apoC-III level, with support from human genetic studies of APOC3 variants. As such, apoC-III has been recognised as a potential therapeutic target for patients with severe hypertriglyceridaemia with one of the most promising apoC-III-targeting drugs, volanesorsen, having recently progressed through Phase III trials.ObjectivesTo exploit a rare loss of function variant in APOC3 (rs138326449) to characterise the potential long-term treatment effects of apoC-III targeting interventions on the metabolome.MethodsIn a recall-by-genotype study, 115 plasma samples were analysed by UHPLC-MS to acquire non-targeted metabolomics data. The study included samples from 57 adolescents and 33 adults. Overall, 12 985 metabolic features were tested for an association with APOC3 genotype.Results144 uniquely annotated metabolites were found to be associated with rs138326449(APOC3). The highest proportion of associated metabolites belonged to the acyl-acyl glycerophospholipid and triacylglyceride metabolite classes. In addition to the anticipated (on-target) reduction of metabolites in the triacylglyceride and related classes, carriers of the rare variant exhibited previously unreported increases in levels of a number of metabolites from the acyl-alkyl glycerophospholipid and ceramide classes.ConclusionOverall, our results suggest that therapies targeting apoC-III may potentially achieve a broad shift in lipid profile that favours better metabolic health.

1051-P: Selective Targeting of Angiopoietin-Like 3 (ANGPTL3) via the Second-Generation Antisense Oligonucleotide (ASO) ISIS-703802 (AKCEA-ANGPTL3-LRx) in Subjects with Familial Partial Lipodystrophy (FPLD)

FPLD is an extreme form of metabolic dyslipidemia and diabetes caused by selective loss of peripheral subcutaneous fat. Currently, there are no approved therapies for this rare cause of diabetes in the U.S. Reductions in circulating levels of the hepatokine ANGPTL3 either by mutations in humans or by targeted drugs in rodents are associated with reductions in triglyceride levels and provide protection from atherosclerosis, making it an attractive target for patients with FPLD and metabolic dyslipidemia. The objective of this proof-of concept, Phase 2, open-label study was to assess the early efficacy and safety of a strategy that targets ANGPTL3 via ISIS-703802 (AKCEA-ANGPTL3-LRx) in patients with FPLD. Four patients with FPLD (3F/1M; age range: 38-47; 1 with LMNA R482Q, 1 with LMNA R584H, and 2 with no causative genetic variant) with diabetes (HbA1c&amp;gt;6.5%) and hypertriglyceridemia (≥ 500 mg/dL or ≥ 200 mg/dL for patients meeting genetic or family history criteria) were included. Patients received the study drug at a subcutaneous dose of 20 mg weekly for 26 weeks. Primary endpoint was the percent change in serum triglycerides from baseline to week 27. All other endpoints were also analyzed at week 27. Treatment resulted in a 60±26 (mean±SD) % reduction in triglycerides from a baseline of 818±432 mg/dL. Consistent with antisense reduction of ANGPTL3 mRNA, circulating ANGPTL3 levels were lowered by 55±10%. Treatment was also associated with 51±27% reduction in circulating apoC3 levels, 64±24% reduction in total VLDL and chylomicron triglycerides, and 18±15% reduction in total cholesterol. In addition, HbA1c showed a modest mean absolute reduction of 0.2±1.0 % The drug was well tolerated and there were no new safety signals observed. Although a small study, these results suggest that targeting ANGPTL3 in patients with FPLD could successfully address metabolic dyslipidemia. Disclosure M. Foss-Freitas: None. B. Akinci: Advisory Panel; Self; Aegerion Pharmaceuticals, Regeneron Pharmaceuticals. Research Support; Self; Gemphire Therapeutics Inc. Speaker’s Bureau; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company, Novartis AG, Novo Nordisk A/S, Sanofi-Aventis, Servier. A.H. Neidert: None. R.P. Hench: None. M. Swaidan: None. E.A. Oral: Consultant; Self; Aegerion Pharmaceuticals, Akcea Therapeutics, Regeneron Pharmaceuticals. Research Support; Self; Aegerion Pharmaceuticals, Akcea Therapeutics, Gemphire Therapeutics Inc., GI Dynamics Inc., Regeneron Pharmaceuticals. Funding Ionis Pharmaceuticals, Inc.; Akcea Therapeutics

Sitagliptin improves plasma apolipoprotein profile in type 2 diabetes: A randomized clinical trial of sitagliptin effect on lipid and glucose metabolism (SLIM) study

AimThis study aims to evaluate the effect of dipeptidyl peptidase-4 inhibitors on lipid metabolism in patients with type 2 diabetes mellitus (T2D). MethodsThis is a multicenter, open-labeled, randomized controlled study. T2D patients with HbA1c 6.9–8.9% (52–74 mmol/mol) who were under treatment with sulfonylurea were randomly allocated to either the sitagliptin group or the non-sitagliptin group. Glucose and lipid metabolism parameters including apolipoproteins (apo), sterols, and urinary albumin were assessed at baseline, 3, and 6 months of the treatment. ResultsA total of 164 patients completed the 6-month observation (n = 81 for sitagliptin and n = 83 for non-sitagliptin). HbA1c decreased in the sitagliptin group but not in the non-sitagliptin group. Serum TG and total, LDL and HDL cholesterol levels did not change in either group. Apo B-48, apo CII, and apo CIII levels decreased in the sitagliptin group, but not in the non-sitagliptin group. The change in urinary albumin was significantly different between the groups with a preferable change in the sitagliptin group. There were no changes in serum sterols levels in the two groups. ConclusionsThe treatment of sitagliptin for 6 months improves the metabolism of glucose and chylomicron and reduces plasma levels of atherogenic lipoproteins in patients with T2D.

Role of angiopoietin-like protein 3 in sugar-induced dyslipidemia in rhesus macaques: suppression by fish oil or RNAi

Angiopoietin-like protein 3 (ANGPTL3) inhibits lipid clearance and is a promising target for managing cardiovascular disease. Here we investigated the effects of a high-sugar (high-fructose) diet on circulating ANGPTL3 concentrations in rhesus macaques. Plasma ANGPTL3 concentrations increased ∼30% to 40% after 1 and 3 months of a high-fructose diet (both P < 0.001 vs. baseline). During fructose-induced metabolic dysregulation, plasma ANGPTL3 concentrations were positively correlated with circulating indices of insulin resistance [assessed with fasting insulin and the homeostatic model assessment of insulin resistance (HOMA-IR)], hypertriglyceridemia, adiposity (assessed as leptin), and systemic inflammation [C-reactive peptide (CRP)] and negatively correlated with plasma levels of the insulin-sensitizing hormone adropin. Multiple regression analyses identified a strong association between circulating APOC3 and ANGPTL3 concentrations. Higher baseline plasma levels of both ANGPTL3 and APOC3 were associated with an increased risk for fructose-induced insulin resistance. Fish oil previously shown to prevent insulin resistance and hypertriglyceridemia in this model prevented increases of ANGPTL3 without affecting systemic inflammation (increased plasma CRP and interleukin-6 concentrations). ANGPTL3 RNAi lowered plasma concentrations of ANGPTL3, triglycerides (TGs), VLDL-C, APOC3, and APOE. These decreases were consistent with a reduced risk of atherosclerosis. In summary, dietary sugar-induced increases of circulating ANGPTL3 concentrations after metabolic dysregulation correlated positively with leptin levels, HOMA-IR, and dyslipidemia. Targeting ANGPTL3 expression with RNAi inhibited dyslipidemia by lowering plasma TGs, VLDL-C, APOC3, and APOE levels in rhesus macaques.

High density lipoprotein and its apolipoprotein-defined subspecies and risk of dementia

Whether HDL is associated with dementia risk is unclear. In addition to apoA1, other apolipoproteins are found in HDL, creating subspecies of HDL that may have distinct metabolic properties. We measured apoA1, apoC3, and apoJ levels in plasma and apoA1 levels in HDL that contains or lacks apoE, apoJ, or apoC3 using a modified sandwich ELISA in a case-cohort study nested within the Ginkgo Evaluation of Memory Study. We included 995 randomly selected participants and 521 participants who developed dementia during a mean of 5.1 years of follow-up. The level of total apoA1 was not significantly related to dementia risk, regardless of the coexistence of apoC3, apoJ, or apoE. Higher levels of total plasma apoC3 were associated with better cognitive function at baseline (difference in Modified Mini-Mental State Examination scores tertile 3 vs. tertile 1: 0.60; 95% CI: 0.23, 0.98) and a lower dementia risk (adjusted hazard ratio tertile 3 vs. tertile 1: 0.73; 95% CI: 0.55, 0.96). Plasma concentrations of apoA1 in HDL and its apolipoprotein-defined subspecies were not associated with cognitive function at baseline or with the risk of dementia during follow-up. Similar studies in other populations are required to better understand the association between apoC3 and Alzheimer's disease pathology.

Human apolipoprotein CIII levels; evaluation of three assay methods

Apolipoprotein CIII (apoCIII) is associated with triglyceride (TG)-rich particles like VLDL and exerts an inhibitory effect of lipoprotein lipase. Increased levels are related to cardiovascular diseases and diabetes and therefore apoCIII has been proposed as a useful biomarker. Even if several commercial assays for measuring apoCIII in human plasma/serum are available, data is scarce concerning their reliability and none is used clinically. In the present study a comparative investigation has been done. Two ELISA-based methods (Cusabio Biotech and Assay Pro) and one nephelometric assay (Siemens Healthcare) were investigated. Serum and plasma samples were obtained from healthy volunteers and from samples sent to the Laboratory of Clinical Chemistry, preferably with higher levels of TGs. The Cusabio Biotech assay did not yield any valid results. However, both the methods from Assay Pro and Siemens Healthcare showed good performance with similar dynamic ranges. The latter assay had lower CV and required less work. In healthy individuals, apoCIII levels were not affected by fasting, freezing or thawing, nor did we find any gender differences. Individuals with elevated levels of TG displayed higher apoCIII values. Females with oral intake of contraceptives had higher levels. In conclusion, the nephelometric assay showed the best performance with the lowest CV, was less labor intensive than an assay based on ELISA and could therefore be suitable for clinical use.

HDL-associated apoCIII plays an independent role in predicting postprandial hypertriglyceridemia

BackgroundThe mechanism for an abnormal pattern of triglyceride (TG) metabolism in response to a meal still needs further investigation. Extensive pieces of evidence have shown that apolipoprotein CIII (apoCIII) is a critical modulator of plasma TG metabolism mostly by inhibiting the hydrolysis of TG. Little is known about the role of apoCIII contained in high density lipoprotein (HDL) in plasma TG metabolism after a meal. MethodsFasting and 4-hour postprandial peripheral venous blood were collected in 91 subjects selected from our hospital. Serum lipid parameters, apoCIII levels and HDL subcomponents were tested by standard laboratory procedures, ELISA, and nuclear magnetic resonance (NMR), respectively. The t-test, and Non-parametric tests were performed to examine differences between groups, Pearson’s correlation and multiple regression analysis were used to assess the correlations between apoCIII (HDL-associated or nonHDL-associated) and postprandial TG. ResultsThere was a significant increase in TG after a meal compared to fasting status [155.40(96.70–251.07) mg/dl.vs.118.53(83.38–173.29)mg/dl, p < 0.001]. However, the total apoCIII levels were unchanged before (11.56(7.89–16.22) mg/dl) and after a meal (11.66(7.75–16.02)mg/dl, p = 0.124), while a significant increase in HDL-associated apoCIII (HDL-apoCIII) was observed from fasting (5.25(3.92–7.83)mg/dl) to post-meal (6.46(4.57–8.76)mg/dl, p = 0.001). Unlike nonHDL-apoCIII, HDL-apoCIII was positively correlated with both fasting and postprandial plasma TG in subjects with baseline plasma TG > 118.53 mg/dl (R = 0.503, p < 0.001 for fasting, R = 0.584, p < 0.001 for postprandial). Besides, in the subjects who had an abnormal TG response to a meal, which was defined as postprandial plasma TG increase of>30% compared to baseline TG levels, postprandial HDL-apoCIII was also increased significantly [5.37(3.52–7.02)mg/dl.vs.6.64(4.61–8.86)mg/dl, p = 0.001]. The enrichment of apoCIII in HDL led to changes of TG, cholesterol, free cholesterol, phospholipid and apoAII contents in HDL particles defined by NMR. ConclusionEnrichment of apoCIII in HDL particles potentially plays an independent role in postprandial hypertriglyceridemia.

Dietary fructose and dyslipidemia: new mechanisms involving apolipoprotein CIII.

Chronic consumption of fructose and fructose-containing sugars leads to dyslipidemia. Apolipoprotein (apo) CIII is strongly associated with elevated levels of triglycerides and cardiovascular disease risk. We reviewed the effects of fructose consumption on apoCIII levels and the role of apoCIII in fructose-induced dyslipidemia. Consumption of fructose increases circulating apoCIII levels compared with glucose. The more marked effects of fructose compared with glucose on apoCIII concentrations may involve the failure of fructose consumption to stimulate insulin secretion. The increase in apoCIII levels after fructose consumption correlates with increased postprandial serum triglyceride. Further, RNA interference of apoCIII prevents fructose-induced dyslipidemia in nonhuman primates. Increases in postprandial apoCIII after fructose, but not glucose consumption, are positively associated with elevated triglycerides in large triglyceride-rich lipoproteins and increased small dense LDL levels. ApoCIII might be causal in the lipid dysregulation observed after consumption of fructose and fructose-containing sugars. Decreased consumption of fructose and fructose-containing sugars could be an effective strategy for reducing circulating apoCIII and subsequently lowering triglyceride levels.

Lipoprotein profile and lipid metabolism of PXB-cells®, human primary hepatocytes from liver-humanized mice: proposal of novel in vitro system for screening anti-lipidemic drugs.

We investigated lipid metabolism in PXB-cells, which are human primary hepatocytes isolated from liver-humanized mice, and HepG2 and HuH-7 human hepatoma cell lines. Lipoprotein levels were higher in PXB-cells than in the 2 other cell lines, and PXB-cells mainly released triglycerides and cholesterol as very low density lipoprotein (VLDL), similar to actual liver tissue, whereas the major lipoprotein released from the 2 hepatoma cell lines was LDL. RT-PCR analysis demonstrated that the gene expression levels of apolipoprotein B100 (ApoB100), the apolipoprotein of VLDL/LDL, were similar in PXB-cells and HepG2 cells, while the overexpression of ApoC2, ApoC3, and ApoE, which are components of VLDL, but not LDL, was observed in PXBcells. A protein immunoassay revealed that ApoB100 levels secreted from PXB-cells and HuH-7 cells were similar; however, ApoC3 levels were higher in PXB-cells than in the two other cell lines. We also examined the anti-lipidemic activities of fenofibrate using this assay system. Fenofibrate suppressed lipoprotein production from PXB-cells in a dose-dependent manner mainly by activating the β-oxidation pathway. These results suggest that PXB-cells produce high levels of lipoproteins and are suitable for screening anti-lipidemic agents.

The effect of a low carbohydrate high fat diet on apolipoproteins and cardiovascular risk

AbstractApolipoproteins (apo) regulate lipoprotein characteristics and lipid metabolism. ApoC-III is a regulator of triglyceride-rich lipoprotein (TRL) metabolism and apolipoproteins are important biomarkers for cardiovascular disease (CVD) risk prediction. A low carbohydrate high fat (LCHF) diet improves cardiometabolic risk, especially via reduction of TRL. However, few studies have compared a LCHF vs. a high carbohydrate (HC), lower fat diet under ad libitum conditions on apoC-III levels. The objectives of this investigation were to measure the effect of a LCHF vs. a HC diet on apoC-III, apoA1, apoB and apoB/apoA1 in 16 healthy Caucasian adults aged 19–64. Ethical approval: Liverpool John Moores University Research Ethics Committee (16/ELS/029); registered with ClinicalTrials.gov (Ref. NCT03257085). Participants randomly assigned to a HC diet (UK Eatwell guidelines; ≥ 50% of energy from carbohydrates) (n = 8), or a LCHF diet (consume &lt; 50 g/day of carbohydrates) (n = 8) provided plasma samples at 0, 4 and 8 weeks. ApoA1 and apoB were analysed by an automated chemistry analyser (Daytona, Randox Laboratories Ltd, UK). ApoC-III was analysed via ELISA (Thermo Fisher Ltd, USA). Factorial 2×3 ANOVA and ANCOVA (IBM SPSS 25®) were undertaken to investigate significant differences and to control for variables influenced by baseline measures and visceral adipose tissue (VAT). Results show 0, 4, and 8 weeks respectively: ApoC-III (LCHF: 19.12 ± 9.14, 16.05 ± 7.95, 15.11 ± 3.17 mg/dl; HC: 22.13 ± 8.38, 28.22 ± 13.85, 22.22 ± 7.7 mg/dl) showed no significant (P = 0.319) change. No significant (P = 0.23) change was also observed in ApoB (LCHF: 107.25 ± 20.35, 111.38 ± 24.81, 111.43 ± 19.93 mg/dl; HC: 94.38 ± 20.79, 105.00 ± 20.13, 99.00 ± 29.09 mg/dl). Similarly apoA1 (LCHF: 158.71 ± 14.27, 166.50 ± 23.09, 173.00 ± 29.42 mg/dl; HC: 164.71 ± 30.25, 172.50 ± 29.44, 174.00 ± 32.83 mg/dl) showed no significant change (P = 0.76). This resulted in a relatively unchanged apoB/A1 throughout the study in both diets (P = 0.30). No significant (P &gt; 0.05) differences were found after 4 weeks or between groups also. ANCOVA revealed a trend (P = 0.06) in apoC-III for a difference between groups (LCHF: Δ-6.6 mg/dl vs. HC: Δ1.2 mg/dl) after 8 weeks but no significant (P &gt; 0.05) changes in other apolipoproteins were detected. These preliminary data reveal that a LCHF diet does not improve the apolipoprotein profile; however, when accounting for other metabolic risk factors (i.e. VAT) there was a trend towards lowering apoC-III levels (P = 0.06). Modulation of apoC-III may lead to improved lipid metabolism, but higher-powered studies are warranted before any improvement on CVD risk can be inferred.

Correlates of pentraxin 3 serum concentration in men and women with type 2 diabetes

Elevated levels of plasma pentraxin 3 (PTX3), a marker of inflammation, are associated with the risk of developing cardiovascular diseases in the general population, as well as in patients with type 2 diabetes (DM2). In this study, we aimed to determine factors associated with PTX3 serum concentrations in men and women with DM2. The study included 116 consecutive patients (67 men and 49 women) with DM2 from an outpatient diabetic clinic. Men were characterised by lower age and higher uric acid, creatinine and bilirubin concentrations and waist/hip ratio than women. In women, low-density lipoprotein cholesterol (LDL-C) levels were higher than in men. In men, median (interquartile range) values of PTX3 concentration were 4.02 (1.99), and in women they were 4.53 (3.31) ng/ml (NS). In men, PTX3 concentrations correlated with total cholesterol (TC), triglycerides, apolipoprotein (Apo) C3, Apo B48, Glc and creatinine levels. In women, PTX3 correlated significantly with TC and LDL-C and Apo B100. Partial regression analysis revealed that after adjusting for age, PTX3 concentrations in men were significantly associated with TC, LDL-C, triglycerides, creatinine, Apo C3 and Apo B48, while in women they were associated with TC, LDL-C and Apo B100. The results could be of importance in sex-specific prevention of vascular complications in DM2 patients.