VLDL, apolipoproteins B, CIII, and E, and risk of recurrent coronary events in the Cholesterol and Recurrent Events (CARE) trial

Increasing the complexity of lipoprotein characterization for cardiovascular risk in type 2 diabetes

The burden of cardiovascular disease is particularly high among individuals with diabetes, even when LDL cholesterol is normal or within the therapeutic target. Despite this, cholesterol accumulates in their arteries, in part, due to persistent atherogenic dyslipidaemia characterized by elevated triglycerides, remnant cholesterol, smaller LDL particles and reduced HDL cholesterol. The causal link between dyslipidaemia and atherosclerosis in T2DM is complex, and our contention is that a deeper understanding of lipoprotein composition and functionality, the vehicle that delivers cholesterol to the artery, will provide insight for improving our understanding of the hidden cardiovascular risk of diabetes. This narrative review covers three levels of complexity in lipoprotein characterization: 1-the information provided by routine clinical biochemistry, 2-advanced nuclear magnetic resonance (NMR)-based lipoprotein profiling and 3-the identification of minor components or physical properties of lipoproteins that can help explain arterial accumulation in individuals with normal LDLc levels, which is typically the case in individuals with T2DM. This document highlights the importance of incorporating these three layers of lipoprotein-related information into population-based studies on ASCVD in T2DM. Such an attempt should inevitably run in parallel with biotechnological solutions that allow large-scale determination of these sets of methodologically diverse parameters.

Relationship of apolipoprotein C-III proteoform composition with ankle-brachial index and peripheral artery disease in the Multi-Ethnic Study of Atherosclerosis (MESA)

BACKGROUND AND AIMS

Apolipoprotein C-III (apoC-III) proteoform composition shows distinct relationships with plasma lipids and cardiovascular risk. The present study tested whether apoC-III proteoforms are associated with risk of peripheral artery disease (PAD).

METHODS

ApoC-III proteoforms, i.e., native (C-III0a), and glycosylated with zero (C-III0b), one (C-III1) or two (C-III2) sialic acids, were measured by mass spectrometry immunoassay on 5,734 Multi-Ethnic Study of Atherosclerosis participants who were subsequently followed for clinical PAD over 17 years. Ankle-brachial index (ABI) was also assessed at baseline and then 3 and 10 years later in 4,830 participants.

RESULTS

Higher baseline C-III0b/C-III1 and lower baseline C-III2/C-III1 were associated with slower decline in ABI (follow-up adjusted for baseline) over time, independently of cardiometabolic risk factors, and plasma triglycerides and HDL cholesterol levels (estimated difference per 1 SD was 0.31 % for both, p < 0.01). The associations between C-III2/C-III1 and changes in ABI were stronger in men (-1.21 % vs. -0.27 % in women), and in Black and Chinese participants (-0.83 % and -0.86 % vs. 0.12 % in White). Higher C-III0b/C-III1 was associated with a trend for lower risk of PAD (HR = 0.84 [95%CI: 0.67-1.04]) that became stronger after excluding participants on lipid-lowering medications (0.73 [95%CI: 0.57-0.94]). Neither change in ABI nor clinical PAD was related to total apoC-III levels.

CONCLUSIONS

We found associations of apoC-III proteoform composition with changes in ABI that were independent of other risk factors, including plasma lipids. Our data further support unique properties of apoC-III proteoforms in modulating vascular health that go beyond total apoC-III levels.

Modification of lipoprotein metabolism and function driving atherogenesis in diabetes

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease, characterized by raised blood glucose levels and impaired lipid metabolism resulting from insulin resistance and relative insulin deficiency. In diabetes, the peculiar plasma lipoprotein phenotype, consisting in higher levels of apolipoprotein B-containing lipoproteins, hypertriglyceridemia, low levels of HDL cholesterol, elevated number of small, dense LDL, and increased non-HDL cholesterol, results from an increased synthesis and impaired clearance of triglyceride rich lipoproteins. This condition accelerates the development of the atherosclerotic cardiovascular disease (ASCVD), the most common cause of death in T2DM patients. Here, we review the alteration of structure, functions, and distribution of circulating lipoproteins and the pathophysiological mechanisms that induce these modifications in T2DM. The review analyzes the influence of diabetes-associated metabolic imbalances throughout the entire process of the atherosclerotic plaque formation, from lipoprotein synthesis to potential plaque destabilization. Addressing the different pathophysiological mechanisms, we suggest improved approaches for assessing the risk of adverse cardiovascular events and clinical strategies to reduce cardiovascular risk in T2DM and cardiometabolic diseases.

Simultaneous quantitative LC-MS/MS analysis of 13 apolipoproteins and lipoprotein (a) in human plasma

Numerous studies have revealed a close correlation between the levels of apolipoproteins (Apos) (including lipoprotein(a) [Lp(a)]) and an increased risk of cardiovascular disease in recent decades. However, clinically, lipid profiling remains limited to the conventional plasma levels of cholesterol, triglyceride, ApoA1, and ApoB, which brings the necessity to quantify more apolipoproteins in human plasma. In this study, we simultaneously quantified 13 apolipoproteins and Lp(a) in 5 μL of human plasma using the LC-MS/MS platform. A method was developed for the precise detection of Lp(a), ApoA1, A2, A5, B, C1, C2, C3, D, E, H, L1, M, and J. Suitable peptides were selected and optimized to achieve clear separation of each peak. Method validation consisting of linearity, sensitivity, accuracy and precision, recovery, and matrix effects was evaluated. The intra-day CV ranged from 0.58% to 14.2% and the inter-day CV ranged from 0.51% to 13.3%. The recovery rates ranged from 89.8% to 113.7%, while matrix effects ranged from 85.4% to 113.9% for all apolipoproteins and Lp(a). Stability tests demonstrated that these apolipoproteins remained stable for 3 days at 4 °C and 7 days at -20 °C. This validated method was successfully applied to human plasma samples obtained from 45 volunteers. The quantitative results of ApoA1, ApoB, and Lp(a) exhibited a close correlation with the results from the immunity transmission turbidity assay. Collectively, we developed a robust assay that can be used for high-throughput quantification of apolipoproteins and Lp(a) simultaneously for investigating related risk factors in patients with dyslipidemia.

A novel mouse model of familial combined hyperlipidemia and atherosclerosis

Within the context of residual cardiovascular risk in post-statin era, emerging evidence from epidemiologic and human genetic studies have demonstrated that triglyceride (TG)-rich lipoproteins and their remnants are causally related to cardiovascular risk. While, carriers of loss-of-function mutations of ApoC3 have low TG levels and are protected from cardiovascular disease (CVD). Of translational significance, siRNAs/antisense oligonucleotide (ASO) targeting ApoC3 is beneficial for patients with atherosclerotic CVD. Therefore, animal models of atherosclerosis with both hypercholesterolemia and hypertriglyceridemia are important for the discovery of novel therapeutic strategies targeting TG-lowering on top of traditional cholesterol-lowering. In this study, we constructed a novel mouse model of familial combined hyperlipidemia through inserting a human ApoC3 transgene (hApoC3-Tg) into C57BL/6 J mice and injecting a gain-of-function variant of adeno-associated virus-proprotein convertase subtilisin/kexin type 9 (AAV-PCSK9)-D377Y concurrently with high cholesterol diet (HCD) feeding for 16 weeks. In the last 10 weeks, hApoC3-Tg mice were orally treated with a combination of atorvastatin (10 mg·kg-1·d-1) and fenofibrate (100 mg·kg-1·d-1). HCD-treated hApoC3-Tg mice demonstrated elevated levels of serum TG, total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C). Oral administration of atorvastatin and fenofibrate significantly decreased the plaque sizes of en face aorta, aortic sinus and innominate artery accompanied by improved lipid profile and distribution. In summary, this novel mouse model is of considerable clinical relevance for evaluation of anti-atherosclerotic drugs by targeting both hypercholesterolemia and hypertriglyceridemia.

Hydroxytyrosol, a Promising Supplement in the Management of Human Stroke: An Exploratory Study

Hydroxytyrosol (HT) is a bioactive olive oil phenol with beneficial effects in a number of pathological situations. We have previously demonstrated that an HT-enriched diet could serve as a beneficial therapeutic approach to attenuate ischemic-stroke-associated damage in mice. Our exploratory pilot study examined this effect in humans. Particularly, a nutritional supplement containing 15 mg of HT/day was administered to patients 24 h after the onset of stroke, for 45 days. Biochemical and oxidative-stress-related parameters, blood pressure levels, serum proteome, and neurological and functional outcomes were evaluated at 45 and 90 days and compared to a control group. The main findings were that the daily administration of HT after stroke could: (i) favor the decrease in the percentage of glycated hemoglobin and diastolic blood pressure, (ii) control the increase in nitric oxide and exert a plausible protective effect in oxidative stress, (iii) modulate the evolution of the serum proteome and, particularly, the expression of apolipoproteins, and (iv) be beneficial for certain neurological and functional outcomes. Although a larger trial is necessary, this study suggests that HT could be a beneficial nutritional complement in the management of human stroke.

Proteomic Determinants of Variation in Cholesterol Efflux: Observations from the Dallas Heart Study

High-density lipoproteins (HDLs) are promising targets for predicting and treating atherosclerotic cardiovascular disease (ASCVD), as they mediate removal of excess cholesterol from lipid-laden macrophages that accumulate in the vasculature. This functional property of HDLs, termed cholesterol efflux capacity (CEC), is inversely associated with ASCVD. HDLs are compositionally diverse, associating with >250 different proteins, but their relative contribution to CEC remains poorly understood. Our goal was to identify and define key HDL-associated proteins that modulate CEC in humans. The proteomic signature of plasma HDL was quantified in 36 individuals in the multi-ethnic population-based Dallas Heart Study (DHS) cohort that exhibited persistent extremely high (>=90th%) or extremely low CEC (<=10th%) over 15 years. Levels of apolipoprotein (Apo)A-I associated ApoC-II, ApoC-III, and ApoA-IV were differentially correlated with CEC in high (r = 0.49, 0.41, and -0.21 respectively) and low (r = -0.46, -0.41, and 0.66 respectively) CEC groups (p for heterogeneity (pHet) = 0.03, 0.04, and 0.003 respectively). Further, we observed that levels of ApoA-I with ApoC-III, complement C3 (CO3), ApoE, and plasminogen (PLMG) were inversely associated with CEC in individuals within the low CEC group (r = -0.11 to -0.25 for subspecies with these proteins vs. r = 0.58 to 0.65 for subspecies lacking these proteins; p < 0.05 for heterogeneity). These findings suggest that enrichment of specific proteins on HDLs and, thus, different subspecies of HDLs, differentially modulate the removal of cholesterol from the vasculature.

Development of New Genome Editing Tools for the Treatment of Hyperlipidemia

Hyperlipidemia is a medical condition characterized by high levels of lipids in the blood. It is often associated with an increased risk of cardiovascular diseases such as heart attacks and strokes. Traditional treatment approaches for hyperlipidemia involve lifestyle modifications, dietary changes, and the use of medications like statins. Recent advancements in genome editing technologies, including CRISPR-Cas9, have opened up new possibilities for the treatment of this condition. This review provides a general overview of the main target genes involved in lipid metabolism and highlights the progress made during recent years towards the development of new treatments for dyslipidemia.

Apo CIII Proteoforms, Plasma Lipids, and Cardiovascular Risk in MESA

BACKGROUND

Apo CIII (apolipoprotein CIII) is an important regulator of triglyceride metabolism and was associated with cardiovascular risk in several cohorts. It is present in 4 major proteoforms, a native peptide (CIII0a), and glycosylated proteoforms with zero (CIII0b), 1 (CIII1, most abundant), or 2 (CIII2) sialic acids, which may differentially modify lipoprotein metabolism. We studied the relationships of these proteoforms with plasma lipids and cardiovascular risk.

METHODS

Apo CIII proteoforms were measured by mass spectrometry immunoassay in baseline plasma samples of 5791 participants of Multi-Ethnic Study of Atherosclerosis, an observational community-based cohort. Standard plasma lipids were collected for up to 16 years and cardiovascular events (myocardial infarction, resuscitated cardiac arrest, or stroke) were adjudicated for up to 17 years.

RESULTS

Apo CIII proteoform composition differed by age, sex, race and ethnicity, body mass index, and fasting glucose. Notably, CIII1 was lower in older participants, men and Black and Chinese (versus White) participants, and higher in obesity and diabetes. In contrast, CIII2 was higher in older participants, men, Black, and Chinese persons, and lower in Hispanic individuals and obesity. Higher CIII2 to CIII1 ratio (CIII2/III1) was associated with lower triglycerides and higher HDL (high-density lipoprotein) in cross-sectional and longitudinal models, independently of clinical and demographic risk factors and total apo CIII. The associations of CIII0a/III1 and CIII0b/III1 with plasma lipids were weaker and varied through cross-sectional and longitudinal analyses. Total apo CIII and CIII2/III1 were positively associated with cardiovascular disease risk (n=669 events, hazard ratios, 1.14 [95% CI, 1.04-1.25] and 1.21 [1.11-1.31], respectively); however, the associations were attenuated after adjustment for clinical and demographic characteristics (1.07 [0.98-1.16]; 1.07 [0.97-1.17]). In contrast, CIII0b/III1 was inversely associated with cardiovascular disease risk even after full adjustment including plasma lipids (0.86 [0.79-0.93]).

CONCLUSIONS

Our data indicate differences in clinical and demographic relationships of apo CIII proteoforms, and highlight the importance of apo CIII proteoform composition in predicting future lipid patterns and cardiovascular disease risk.

Trends in lipid profiles and control of LDL-C among adults with diabetes in the United States: An analysis of NHANES 2007-2018

BACKGROUND AND AIM

To determine trends in lipid profiles and lipid control in US adults with diabetes and assess variation in these trends across sex and race/ethnicity from 2007 to 2018.

METHODS AND RESULTS

Serial cross-sectional analysis of data from diabetic adults participating in the National Health and Nutrition Examination Survey (NHANES; 2007-2008 to 2017-2018). Among the 6116 participants included (weighted mean age, 61.0 years; 50.7% men), age-adjusted TC (p for trend < 0.001), LDL-C (p for trend < 0.001), TG (p for trend = 0.006), TG/HDL-C (p for trend = 0.014) and VLDL-C (p for trend = 0.015) decreased significantly. Age-adjusted LDL-C levels were consistently higher in women than in men over the study period. Age-adjusted LDL-C improved significantly for diabetic whites and blacks but did not change significantly for the other races/ethnicity. Lipid parameters improved for non-coronary heart disease (CHD) diabetic adults, except for HDL-C, while no lipid parameter significantly changed for diabetic adults with concomitant CHD. Among diabetic adults receiving statin therapy, age-adjusted lipid control remained unchanged from 2007 to 2018, as did adults with concomitant CHD. However, age-adjusted lipid control improved significantly for men (p for trend < 0.01) and diabetic Mexican Americans (p for trend < 0.01). In 2015-2018, female diabetic participants receiving statins had lower odds of achieving lipid control (OR: 0.55; 95% CI: 0.35-0.84; P = 0.006) than men. Differences in lipid control across different races/ethnicities no longer existed.

CONCLUSIONS

Lipid profiles improved in the US adults with diabetes from 2007 to 2018. Although rates of lipid control did not improve nationally in adults receiving statins, these patterns varied by sex and race/ethnicity.

A Current Update on the Role of HDL-Based Nanomedicine in Targeting Macrophages in Cardiovascular Disease

High-density lipoproteins (HDL) are complex endogenous nanoparticles involved in important functions such as reverse cholesterol transport and immunomodulatory activities, ensuring metabolic homeostasis and vascular health. The ability of HDL to interact with a plethora of immune cells and structural cells places it in the center of numerous disease pathophysiologies. However, inflammatory dysregulation can lead to pathogenic remodeling and post-translational modification of HDL, rendering HDL dysfunctional or even pro-inflammatory. Monocytes and macrophages play a critical role in mediating vascular inflammation, such as in coronary artery disease (CAD). The fact that HDL nanoparticles have potent anti-inflammatory effects on mononuclear phagocytes has opened new avenues for the development of nanotherapeutics to restore vascular integrity. HDL infusion therapies are being developed to improve the physiological functions of HDL and to quantitatively restore or increase the native HDL pool. The components and design of HDL-based nanoparticles have evolved significantly since their initial introduction with highly anticipated results in an ongoing phase III clinical trial in subjects with acute coronary syndrome. The understanding of mechanisms involved in HDL-based synthetic nanotherapeutics is critical to their design, therapeutic potential and effectiveness. In this review, we provide a current update on HDL-ApoA-I mimetic nanotherapeutics, highlighting the scope of treating vascular diseases by targeting monocytes and macrophages.

Role of APOC3 3238C/G polymorphism in HIV-associated neurocognitive disorder

Apolipoprotein not only have a role in cholesterol metabolism but also play a role in normal brain function. Apolipoprotein gene polymorphisms are known risk factors for a number of mental and neurological disorders. The expression of brain apolipoproteins is significantly altered in several brain disorders. Therefore, we assed ApoC33238C/G polymorphism in a total of 248 patient infected with HIV (45 with HAND, 89 without HAND, 114 without ART) and 134 healthy controls using PCR-RFLP. ApoC3 3238CG, 3238GG genotypes and 3238G allele showed a non-significant increased risk for severity of HAND (P = 0.16, OR = 1.83; P = 0.32, OR = 2.78; P = 0.10, OR = 1.65) while comparing individuals with and without HAND. ApoC3 3238GG genotype and 3238G allele revealed an increased risk for disease progression when compared between HIV patients with and without ART (P = 0.55, OR = 1.76; P = 0.65, OR = 1.12) though risk could not reach statistical significance. ApoC3 3238GG genotype and 3238G allele were associated with the reduced risk of acquiring HIV infection when comparing HIV patients who are not on ART with healthy controls (P = 0.05, OR = 0.29; P = 0.04, OR = 0.66). In HIV patients on ART,ApoC3 3238GG genotype showed an increased susceptibility to development of HAND (P = 0.48, OR = 2.24) when comparing alcohol drinkers and non-drinkers however risk could not reach statistical significance. In conclusion, the genotype ApoC33238GG displayed an inclination of risk for the severity of HAND and HIV disease progression. The polymorphism of APOC3 3238C/G may have a role to reduce the risk for acquisition of HIV infection. ApoC33238GG genotype in presence of alcohol may increase susceptibility to development of HAND.

HDL cholesterol efflux capacity and phospholipid content are associated with the severity of acute ischemic stroke and predict its outcome

BACKGROUND/AIMS

Impaired high-density lipoprotein (HDL) function and composition are more strongly related to cardiovascular morbidity than HDL concentration. However, it is unclear whether HDL function and composition predict ischemic stroke severity and outcome. We aimed to evaluate these associations.

METHODS

We prospectively studied 199 consecutive patients who were admitted with acute ischemic stroke. The severity of stroke was evaluated at admission with the National Institutes of Health Stroke Scale (NIHSS). Severe stroke was defined as NIHSS ≥ 5. The outcome was assessed with dependency at discharge (modified Rankin scale 2-5) and in-hospital mortality. Cholesterol efflux capacity (CEC), phospholipid levels, lecithin:cholesterol acyl transferase (LCAT)-phospholipase activity, paraoxonase-1 (PON1)-arylesterase activity and serum amyloid A1 (SAA1) content of HDL were measured.

RESULTS

CEC, phospholipid levels and LCAT-phospholipase activity of HDL were lower and SAA1 content of HDL was higher in patients with severe stroke. Patients who were dependent at discharge had lower CEC, PON1-arylesterase activity, phospholipid content and LCAT-phospholipase activity of HDL and higher HDL-SAA1 content. Independent predictors of dependency at discharge were the NIHSS at admission (RR 2.60, 95% CI 1.39-4.87), lipid-lowering treatment (RR 0.17, 95% CI 0.01-0.75), HDL-CEC (RR 0.21, 95% CI 0.05-0.87) and HDL-associated PON1-arylesterase activity (RR 0.95, 95% CI 0.91-0.99). In patients who died during hospitalization, phospholipids, LCAT-phospholipase and PON1-arylesterase activities of HDL were lower.

CONCLUSIONS

Changes in CEC and composition of HDL appear to be associated with the severity and outcome of acute ischemic stroke and could represent biomarkers that may inform risk stratification and management strategies in these patients.

Associations between Alcohol Consumption and HDL Subspecies Defined by ApoC3, ApoE and ApoJ: the Cardiovascular Health Study

Alcohol consumption increases circulating high-density lipoprotein cholesterol (HDL-C), but HDL protein cargo may better reflect HDL function. This study examined the associations between alcohol intake and HDL subspecies containing or lacking apoC3, apoE, and apoJ in a well-phenotyped cohort. We performed a cross-sectional analysis of 2092 Cardiovascular Health Study participants aged 70 or older with HDL subspecies measured in stored specimens from 1998 to 1999. Associations between alcohol intake and apoA1 defined HDL subspecies lacking or containing apoC3, apoE, and apoJ, and circulating levels of total apoA1, apoC3, apoE, and apoJ were examined. HDL subspecies lacking and containing apoC3, apoE, and apoJ were all positively associated with alcohol intake, with ∼1% per additional drink per week or ∼7% per additional drink per day (subspecies without the apolipoproteins, P ≤ 2 × 10^-9, subspecies with the apolipoproteins, P ≤ 3 × 10^-5). Total apoA1 was also directly associated with alcohol consumption, with a 1% increase per additional drink per week (P = 1 × 10^-14). Total apoC3 blood levels were 0.5% higher per additional drink per week (P = 0.01), but the association was driven by a few heavily drinking men. Alcohol intake was positively associated with HDL subspecies lacking and containing apoC3, apoE, or apoJ, and with total plasma apoA1. ApoC3 was directly, albeit not as robustly associated with alcohol intake. HDL protein cargo is crucial for its anti-atherosclerotic functions, but it remains to be determined whether HDL subspecies play a role in the putative association between limited alcohol intake and lower risk of coronary heart disease.

Apolipoprotein C3 and necrotic core volume are correlated but also associated with future cardiovascular events

We aimed to clarify the relationship between apolipoprotein C3 (apo-C3) and the vascular composition of lesion plaque in stable coronary disease (SCD) before percutaneous coronary intervention (PCI), and to investigate major adverse cardiovascular events (MACEs) within 4 years. Data of 98 consecutive patients with SCD who underwent PCI between November 1, 2012, and March 10, 2015, were analyzed. Laboratory and virtual histology-intravascular ultrasound (VH-IVUS) examinations of culprit lesions were conducted before PCI. Patients were divided according to median apo-C3 into low apo-C3 (≤ 8.5 mg/dL) and high apo-C3 (> 8.5 mg/dL) groups. VH-IVUS data indicated that the percentage of necrotic core volume (%NC) was significantly higher in the high apo-C3 group than in the low apo-C3 group. Moreover, the %NC significantly correlated with the apo-C3 level (R = 0.2109, P = 0.037). Kaplan–Meier curve analysis revealed that freedom from MACEs exhibited a greater decrease in the high apo-C3 group than in the low apo-C3 group, and in the high %NC group than in the low %NC group. Multivariate Cox hazards analysis showed that the %NC and high apo-C3 were independent predictors of 4 year MACEs. Apo-C3 may be a useful marker of future MACEs in patients with SCD after PCI and contribute to %NC growth.

Pharmacokinetic Interaction between Atorvastatin and Omega-3 Fatty Acid in Healthy Volunteers

The interaction between statins and omega-3 fatty acids remains controversial. The aim of this phase 1 trial was to evaluate the pharmacokinetics of drug-drug interaction between atorvastatin and omega-3 fatty acids. Treatments were once-daily oral administrations of omega-3 (4 g), atorvastatin (40 mg), and both for 14 days, 7 days, and 14 days, respectively, with washout periods. The concentrations of atorvastatin, 2-OH-atorvastatin, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) were determined with LC-MS/MS. Parameters of DHA and EPA were analyzed after baseline correction. A total of 37 subjects completed the study without any major violations. The geometric mean ratios (GMRs) and 90% confidence intervals (CIs) of the co-administration of a single drug for the area under the concentration-time curve during the dosing interval at steady state of atorvastatin, 2-OH-atorvastatin, DHA, and EPA were 1.042 (0.971-1.118), 1.185 (1.113-1.262), 0.157 (0.091-0.271), and 0.557 (0.396-0.784), respectively. The GMRs (90% Cis) for the co-administration at steady state of atorvastatin, 2-OH-atorvastatin, DHA, and EPA were 1.150 (0.990-1.335), 1.301 (1.2707-1.1401), 0.320 (0.243-0.422), and 0.589 (0.487-0.712), respectively. The 90% CIs for most primary endpoints were outside the range of typical bioequivalence, indicating a pharmacokinetic interaction between atorvastatin and omega-3.

Regulation of cholesterol homeostasis in health and diseases: from mechanisms to targeted therapeutics

Disturbed cholesterol homeostasis plays critical roles in the development of multiple diseases, such as cardiovascular diseases (CVD), neurodegenerative diseases and cancers, particularly the CVD in which the accumulation of lipids (mainly the cholesteryl esters) within macrophage/foam cells underneath the endothelial layer drives the formation of atherosclerotic lesions eventually. More and more studies have shown that lowering cholesterol level, especially low-density lipoprotein cholesterol level, protects cardiovascular system and prevents cardiovascular events effectively. Maintaining cholesterol homeostasis is determined by cholesterol biosynthesis, uptake, efflux, transport, storage, utilization, and/or excretion. All the processes should be precisely controlled by the multiple regulatory pathways. Based on the regulation of cholesterol homeostasis, many interventions have been developed to lower cholesterol by inhibiting cholesterol biosynthesis and uptake or enhancing cholesterol utilization and excretion. Herein, we summarize the historical review and research events, the current understandings of the molecular pathways playing key roles in regulating cholesterol homeostasis, and the cholesterol-lowering interventions in clinics or in preclinical studies as well as new cholesterol-lowering targets and their clinical advances. More importantly, we review and discuss the benefits of those interventions for the treatment of multiple diseases including atherosclerotic cardiovascular diseases, obesity, diabetes, nonalcoholic fatty liver disease, cancer, neurodegenerative diseases, osteoporosis and virus infection.

Recent Updates in Hypertriglyceridemia Management for Cardiovascular Disease Prevention

PURPOSE OF REVIEW

Mounting evidence continues to support the causal role of triglyceride-rich lipoproteins (TRL) in the development of atherosclerotic cardiovascular disease (ASCVD). Substantial residual ASCVD risk remains among high-risk patients who have elevated triglycerides despite reduction in low-density lipoprotein cholesterol (LDL-C) with statin therapy. Ongoing research efforts have focused on evaluating triglyceride-lowering therapies among patients with hypertriglyceridemia.

RECENT FINDINGS

The REDUCE-IT trial showed that the addition of icosapent ethyl, a highly purified form of eicosapentaenoic acid (EPA), can reduce vascular events among statin-treated individuals with elevated triglycerides who have either clinical ASCVD or diabetes plus another risk factor. Although additional evidence for EPA has emerged from other trials, conflicting results have been reported by subsequent trials that tested different omega-3 fatty acid formulations. Randomized clinical trials have not demonstrated incremental ASCVD benefit of fibrates on background of statin therapy, but fibrates are used to help prevent pancreatitis in patients with severe hypertriglyceridemia. Selective inhibitors of apolipoprotein C-III (apoC3) and angiopoietin-like protein 3 (ANGPTL3), proteins that are involved in metabolism of TRLs by regulating lipoprotein lipase, have been tested in selected patient populations and showed significant reduction in triglyceride and LDL-C levels. Statin therapy continues to be the cornerstone of pharmacologic reduction of cardiovascular risk. High-dose EPA in the form of icosapent ethyl has been demonstrated to have cardiovascular benefit on top of statins in persons with elevated triglycerides at high ASCVD risk. Ongoing clinical trials are evaluating novel selective therapies such as apoC3 and ANGPTL3 inhibitors.

New, Novel Lipid-Lowering Agents for Reducing Cardiovascular Risk: Beyond Statins

Statins are the cornerstone of the prevention and treatment of atherosclerotic cardiovascular disease (ASCVD). However, even under optimal statin therapy, a significant residual ASCVD risk remains. Therefore, there has been an unmet clinical need for novel lipid-lowering agents that can target low-density lipoprotein cholesterol (LDL-C) and other atherogenic particles. During the past decade, several drugs have been developed for the treatment of dyslipidemia. Inclisiran, a small interfering RNA that targets proprotein convertase subtilisin/kexin type 9 (PCSK9), shows comparable effects to that of PCSK9 monoclonal antibodies. Bempedoic acid, an ATP citrate lyase inhibitor, is a valuable treatment option for the patients with statin intolerance. Pemafibrate, the first selective peroxisome proliferator-activated receptor alpha modulator, showed a favorable benefit-risk balance in phase 2 trial, but the large clinical phase 3 trial (PROMINENT) was recently stopped for futility based on a late interim analysis. High dose icosapent ethyl, a modified eicosapentaenoic acid preparation, shows cardiovascular benefits. Evinacumab, an angiopoietin-like 3 (ANGPTL3) monoclonal antibody, reduces plasma LDL-C levels in patients with refractory hypercholesterolemia. Novel antisense oligonucleotides targeting apolipoprotein C3 (apoC3), ANGPTL3, and lipoprotein(a) have significantly attenuated the levels of their target molecules with beneficial effects on associated dyslipidemias. Apolipoprotein A1 (apoA1) is considered as a potential treatment to exploit the athero-protective effects of high-density lipoprotein cholesterol (HDL-C), but solid clinical evidence is necessary. In this review, we discuss the mode of action and clinical outcomes of these novel lipid-lowering agents beyond statins.

Emerging Evidence of Pathological Roles of Very-Low-Density Lipoprotein (VLDL)

Embraced with apolipoproteins (Apo) B and Apo E, triglyceride-enriched very-low-density lipoprotein (VLDL) is secreted by the liver into circulation, mainly during post-meal hours. Here, we present a brief review of the physiological role of VLDL and a systemic review of the emerging evidence supporting its pathological roles. VLDL promotes atherosclerosis in metabolic syndrome (MetS). VLDL isolated from subjects with MetS exhibits cytotoxicity to atrial myocytes, induces atrial myopathy, and promotes vulnerability to atrial fibrillation. VLDL levels are affected by a number of endocrinological disorders and can be increased by therapeutic supplementation with cortisol, growth hormone, progesterone, and estrogen. VLDL promotes aldosterone secretion, which contributes to hypertension. VLDL induces neuroinflammation, leading to cognitive dysfunction. VLDL levels are also correlated with chronic kidney disease, autoimmune disorders, and some dermatological diseases. The extra-hepatic secretion of VLDL derived from intestinal dysbiosis is suggested to be harmful. Emerging evidence suggests disturbed VLDL metabolism in sleep disorders and in cancer development and progression. In addition to VLDL, the VLDL receptor (VLDLR) may affect both VLDL metabolism and carcinogenesis. Overall, emerging evidence supports the pathological roles of VLDL in multi-organ diseases. To better understand the fundamental mechanisms of how VLDL promotes disease development, elucidation of the quality control of VLDL and of the regulation and signaling of VLDLR should be indispensable. With this, successful VLDL-targeted therapies can be discovered in the future.

Apolipoprotein C3-Rich Low-Density Lipoprotein Induces Endothelial Cell Senescence via FBXO31 and Its Inhibition by Sesamol In Vitro and In Vivo

Premature endothelial senescence decreases the atheroprotective capacity of the arterial endothelium. Apolipoprotein C3 (ApoC3) delays the catabolism of triglyceride-rich particles and plays a critical role in atherosclerosis progression. FBXO31 is required for the intracellular response to DNA damage, which is a significant cause of cellular senescence. Sesamol is a natural antioxidant with cardiovascular-protective properties. In this study, we aimed to examine the effects of ApoC3-rich low-density lipoprotein (AC3RL) mediated via FBXO31 on endothelial cell (EC) senescence and its inhibition by sesamol. AC3RL and ApoC3-free low-density lipoproteins (LDL) (AC3(-)L) were isolated from the plasma LDL of patients with ischemic stroke. Human aortic endothelial cells (HAECs) treated with AC3RL induced EC senescence in a dose-dependent manner. AC3RL induced HAEC senescence via DNA damage. However, silencing FBXO31 attenuated AC3RL-induced DNA damage and reduced cellular senescence. Thus, FBXO31 may be a novel therapeutic target for endothelial senescence-related cardiovascular diseases. Moreover, the aortic arch of hamsters fed a high-fat diet with sesamol showed a substantial reduction in their atherosclerotic lesion size. In addition to confirming the role of AC3RL in aging and atherosclerosis, we also identified AC3RL as a potential therapeutic target that can be used to combat atherosclerosis and the onset of cardiovascular disease in humans.

Apolipoprotein C-III predicts cardiovascular events and mortality in individuals with type 1 diabetes and albuminuria

OBJECTIVES

We studied apolipoprotein C-III (apoC-III) in relation to diabetic kidney disease (DKD), cardiovascular outcomes, and mortality in type 1 diabetes.

METHODS

The cohort comprised 3966 participants from the prospective observational Finnish Diabetic Nephropathy Study. Progression of DKD was determined from medical records. A major adverse cardiac event (MACE) was defined as acute myocardial infarction, coronary revascularization, stroke, or cardiovascular mortality through 2017. Cardiovascular and mortality data were retrieved from national registries.

RESULTS

ApoC-III predicted DKD progression independent of sex, diabetes duration, blood pressure, HbA_1c , smoking, LDL-cholesterol, lipid-lowering medication, DKD category, and remnant cholesterol (hazard ratio [HR] 1.43 [95% confidence interval 1.05-1.94], p = 0.02). ApoC-III also predicted the MACE in a multivariable regression analysis; however, it was not independent of remnant cholesterol (HR 1.05 [0.81-1.36, p = 0.71] with remnant cholesterol; 1.30 [1.03-1.64, p = 0.03] without). DKD-specific analyses revealed that the association was driven by individuals with albuminuria, as no link between apoC-III and the outcome was observed in the normal albumin excretion or kidney failure categories. The same was observed for mortality: Individuals with albuminuria had an adjusted HR of 1.49 (1.03-2.16, p = 0.03) for premature death, while no association was found in the other groups. The highest apoC-III quartile displayed a markedly higher risk of MACE and death than the lower quartiles; however, this nonlinear relationship flattened after adjustment.

CONCLUSIONS

The impact of apoC-III on MACE risk and mortality is restricted to those with albuminuria among individuals with type 1 diabetes. This study also revealed that apoC-III predicts DKD progression, independent of the initial DKD category.

Ethnic differences in ApoC-III concentration and the risk of cardiovascular disease: No evidence for the cardioprotective role of rare/loss of function APOC3 variants in non-Europeans

BACKGROUND

Hypertriglyceridemia is as an independent risk factor for cardiovascular disease (CVD). Apolipoprotein C-III (ApoC-III) is known to regulate triglyceride (TG) metabolism. However, the causal association between ApoC-III and CVD development is unclear. The objectives were to examine the impact of ApoC-III concentration on TG and lipoproteins and investigate the role of known rare loss-of-function APOC3 variants for modulating ApoC-III, TG concentrations and CVD risk in different ethnic groups.

METHODS

Plasma ApoC-III levels were measured in a multiethnic sample of 518 individuals comprising 271 Asian Indians (Sikhs), 87 Caucasians, 80 African Americans, and 80 Hispanics.

RESULTS

ApoC-III levels showed a robust association with TG in Asian Indians (r = 0.5, p = 1.1 × 10^-23), Caucasians (r = 0.4, p = 7.2 × 10^-4), and Hispanics (r = 0.9, p = 2.7x × 10^-28). African Americans had lowest ApoC-III and TG concentrations and highest (44%) prevalence of coronary artery disease (CAD). ApoC-III levels correlated with fasting blood glucose (r = 0.25, p = 6.1 × 10^-5) in Asian Indians and central adiposity in Hispanics (waist: r = 0.22, p = 0.05; waist-hip ratio: r = 0.24, p = 0.04). The carriers of rare variants IVS1-2G-A (rs373975305); A43T (rs147210663) and IVS3 + 1G-T (rs140621530) showed high TG but not low ApoC-III levels in Asian Indians and Caucasians.

CONCLUSION

These results highlight the challenges of generalizing antisense ApoC-III inhibition for treating atherosclerotic disease in dyslipidemia that may benefit only specific sub-populations. The observed ethnic differences in ApoC-III concentrations and CAD risk factors, emphasize in-depth genetic and metabolomics evaluations on diverse ancestries.

A New Modality in Dyslipidemia Treatment: Antisense Oligonucleotide Therapy

There are unmet needs for pharmacologic agents beyond current medications, such as statins, to effectively lower low-density lipoprotein cholesterol levels to target goals, especially in patients with very high or extremely high risk. Pharmacological targeting of mRNA represents an emerging, innovative approach with the potential to expand upon current therapies. In RNA-targeted therapeutics, a novel approach is the use of chemically modified oligonucleotides to inhibit the production of target proteins at their sites of gene coding. There are two main classes of RNA-targeted therapeutics: single-stranded antisense oligonucleotides (ASOs) and double-stranded small inhibiting RNAs. ASOs are synthetic molecules with a length of 15–30 nucleotides that are designed specifically to bind to a target mRNA in a sequence-specific manner. Using these agents to inhibit the translation of key regulatory proteins, such as apolipoprotein CIII, apolipoprotein(a), and angiopoietin-like protein 3, has demonstrated treatment efficacy for dyslipidemia. Many cardiovascular outcome trials with ASOs are ongoing. As clinicians, we must carefully monitor the long-term safety and efficacy of this new modality through large clinical trials in the future.

Transient hypertriglyceridemia: a common finding during Epstein-Barr virus-induced infectious mononucleosis

Background

Hypertriglyceridemia can occur in lymphoproliferative disorders. Infectious mononucleosis is a self-limiting, benign lymphoproliferative disorder. This study aimed to investigate the serum triglyceride concentrations and their change over time in patients with infectious mononucleosis.

Methods

We evaluated an adult patient with severe hypertriglyceridemia (>1000 mg/dL) during infectious mononucleosis and reviewed the records of 360 patients admitted to our hospital because of infectious mononucleosis (median age, 19 years; range, 15-87 years; 51.4% male). We compared the serum triglyceride concentrations with those of a control sample from the general population (n=75). A second triglyceride measurement, obtained during convalescence (median of 30 days after the initial determination), was available for 160 patients.

Results

The triglyceride concentrations in the acute phase (median: 156 mg/dL) were significantly higher than those of the controls (median, 76 mg/dL; P<0.001). A total of 194 (53.9%) patients presented with hypertriglyceridemia (>150 mg/dL), which was more common in the patients older than 30 years than in the younger patients (78.6% vs. 50.6%; P<0.001). A significant correlation (P<0.005) was observed between the triglyceride levels and white blood cell counts, total cholesterol levels, and liver damage markers. The triglyceride concentrations decreased during convalescence (P<0.001) and were lower than the initial measurement in 83.7% of the cases. Conversely, the total cholesterol concentrations during the acute phase were lower than those of the controls and increased during convalescence (P<0.001).

Conclusions

Patients with severe infectious mononucleosis frequently show mild, transient hypertriglyceridemia. Further studies are needed to elucidate the mechanisms underlying this finding.

Apolipoprotein B and Cardiovascular Disease: Biomarker and Potential Therapeutic Target

Apolipoprotein (apo) B, the critical structural protein of the atherogenic lipoproteins, has two major isoforms: apoB48 and apoB100. ApoB48 is found in chylomicrons and chylomicron remnants with one apoB48 molecule per chylomicron particle. Similarly, a single apoB100 molecule is contained per particle of very-low-density lipoprotein (VLDL), intermediate density lipoprotein, LDL and lipoprotein(a). This unique one apoB per particle ratio makes plasma apoB concentration a direct measure of the number of circulating atherogenic lipoproteins. ApoB levels indicate the atherogenic particle concentration independent of the particle cholesterol content, which is variable. While LDL, the major cholesterol-carrying serum lipoprotein, is the primary therapeutic target for management and prevention of atherosclerotic cardiovascular disease, there is strong evidence that apoB is a more accurate indicator of cardiovascular risk than either total cholesterol or LDL cholesterol. This review examines multiple aspects of apoB structure and function, with a focus on the controversy over use of apoB as a therapeutic target in clinical practice. Ongoing coronary artery disease residual risk, despite lipid-lowering treatment, has left patients and clinicians with unsatisfactory options for monitoring cardiovascular health. At the present time, the substitution of apoB for LDL-C in cardiovascular disease prevention guidelines has been deemed unjustified, but discussions continue.

APOC3 genetic variation, serum triglycerides, and risk of coronary artery disease in Asian Indians, Europeans, and other ethnic groups

BACKGROUND

Hypertriglyceridemia has emerged as a critical coronary artery disease (CAD) risk factor. Rare loss-of-function (LoF) variants in apolipoprotein C-III have been reported to reduce triglycerides (TG) and are cardioprotective in American Indians and Europeans. However, there is a lack of data in other Europeans and non-Europeans. Also, whether genetically increased plasma TG due to ApoC-III is causally associated with increased CAD risk is still unclear and inconsistent. The objectives of this study were to verify the cardioprotective role of earlier reported six LoF variants of APOC3 in South Asians and other multi-ethnic cohorts and to evaluate the causal association of TG raising common variants for increasing CAD risk.

METHODS

We performed gene-centric and Mendelian randomization analyses and evaluated the role of genetic variation encompassing APOC3 for affecting circulating TG and the risk for developing CAD.

RESULTS

One rare LoF variant (rs138326449) with a 37% reduction in TG was associated with lowered risk for CAD in Europeans (p = 0.007), but we could not confirm this association in Asian Indians (p = 0.641). Our data could not validate the cardioprotective role of other five LoF variants analysed. A common variant rs5128 in the APOC3 was strongly associated with elevated TG levels showing a p-value 2.8 × 10- 424. Measures of plasma ApoC-III in a small subset of Sikhs revealed a 37% increase in ApoC-III concentrations among homozygous mutant carriers than the wild-type carriers of rs5128. A genetically instrumented per 1SD increment of plasma TG level of 15 mg/dL would cause a mild increase (3%) in the risk for CAD (p = 0.042).

CONCLUSIONS

Our results highlight the challenges of inclusion of rare variant information in clinical risk assessment and the generalizability of implementation of ApoC-III inhibition for treating atherosclerotic disease. More studies would be needed to confirm whether genetically raised TG and ApoC-III concentrations would increase CAD risk.

Volanesorsen for treatment of familial chylomicronemia syndrome

INTRODUCTION

Familial chylomicronemia syndrome (FCS) is a rare subtype of severe hypertriglyceridemia that affects ~1 in 100, 000 to 1,000,000 individuals. The major risk to health is acute pancreatitis. FCS is defined by biallelic loss-of-function mutations in one of five canonical genes that encode proteins critical to lipolysis of large triglyceride-rich lipoprotein particles. Unlike the vast majority of patients with severe hypertriglyceridemia, FCS patients lack any lipolytic capacity and are thus resistant to standard medications.

AREAS COVERED

This review focuses on a mechanism that effectively reduces elevated triglyceride levels in FCS, namely interference of synthesis of apolipoprotein (apo) C-III. Volanesorsen is an antisense RNA drug administered subcutaneously that knocks down apo C-III, resulting in dramatic reductions in triglyceride levels both in FCS patients and in the wider population of subjects with severe hypertriglyceridemia.

EXPERT OPINION

Volanesorsen is a highly effective treatment to reduce elevated triglycerides in FCS patients, providing proof-of-concept of the validity of targeting apo C-III. However, off target effects of volanesorsen, including thrombocytopenia, may ultimately limit its use. Nonetheless, building on the knowledge derived from the volanesorsen experience, there is intensified interest in promising newer agents that also target apo C-III but have technical modifications that limit potential off target adverse effects.

ANGPTL3 and Apolipoprotein C-III as Novel Lipid-Lowering Targets

PURPOSE OF REVIEW

Despite significant progress in plasma lipid lowering strategies, recent clinical trials highlight the existence of residual cardiovascular risk. Angiopoietin-like protein 3 (ANGPTL3) and apolipoprotein C-III (Apo C-III) have been identified as novel lipid-lowering targets.

RECENT FINDINGS

Apo C-III and ANGPTL3 have emerged as novel regulators of triglyceride (TG) and low-density lipoprotein-cholesterol (LDL-C) levels. ANGPTL3 is an inhibitor of lipoprotein lipase (LPL), reducing lipolysis of Apo B-containing lipoproteins. Loss-of-function ANGPLT3 mutations are associated with reduced plasma cholesterol and TG, while novel ANGPLT3 inhibition strategies, including monoclonal antibodies (evinacumab), ANGPLT3 antisense oligonucleotides (IONIS-ANGPTL3-L_Rx), and small interfering RNA (siRNA) silencing techniques (ARO-ANG3), result in increased lipolysis and significant reductions of LDL-C and TG levels in phase I and II clinical trials. Similarly, Apo C-III inhibits LPL while promoting the hepatic secretion of TG-rich lipoproteins and preventing their clearance. Loss-of-function APOC3 mutations have been associated with reduced TG levels. Targeting of Apo C-III with volanesorsen, an APOC3 siRNA, results in significant reduction in plasma TG levels but possibly also increased risk for thrombocytopenia, as recently demonstrated in phase I, II, and III clinical trials. ARO-APOC3 is a novel siRNA-based agent targeting Apo C-III which is currently under investigation with regard to its lipid-lowering efficiency. ANGPTL3 and Apo C-III targeting agents have demonstrated striking lipid-lowering effects in recent clinical trials; however, more thorough safety and efficacy data are required. Here, we evaluate the role of ANGPLT3 and Apo C-III in lipid metabolism, present the latest clinical advances targeting those molecules, and outline the remaining scientific challenges on residual lipid-associated cardiovascular risk.

Apolipoprotein CIII Is an Important Piece in the Type-1 Diabetes Jigsaw Puzzle

It is well known that type-2 diabetes mellitus (T2D) is increasing worldwide, but also the autoimmune form, type-1 diabetes (T1D), is affecting more people. The latest estimation from the International Diabetes Federation (IDF) is that 1.1 million children and adolescents below 20 years of age have T1D. At present, we have no primary, secondary or tertiary prevention or treatment available, although many efforts testing different strategies have been made. This review is based on the findings that apolipoprotein CIII (apoCIII) is increased in T1D and that in vitro studies revealed that healthy β-cells exposed to apoCIII became apoptotic, together with the observation that humans with higher levels of the apolipoprotein, due to mutations in the gene, are more susceptible to developing T1D. We have summarized what is known about apoCIII in relation to inflammation and autoimmunity in in vitro and in vivo studies of T1D. The aim is to highlight the need for exploring this field as we still are only seeing the top of the iceberg.

Targeting RNA With Antisense Oligonucleotides and Small Interfering RNA: JACC State-of-the-Art Review

There is an unmet clinical need to reduce residual cardiovascular risk attributable to apolipoprotein B-containing lipoproteins, particularly low-density lipoprotein and remnant particles. Pharmacological targeting of messenger RNA represents an emerging, innovative approach. Two major classes of agents have been developed-antisense oligonucleotides and small interfering RNA. Early problems with their use have been overcome by conjugation with N-acetylgalactosamine, an adduct that targets their delivery to the primary site of action in the liver. Using these agents to inhibit the translation of key regulatory proteins such as PCSK9, apolipoprotein CIII, apolipoprotein(a), and angiopoietin-like 3 has been shown to be effective in attenuating dyslipidemic states. Cardiovascular outcome trials with N-acetylgalactosamine-conjugated RNA-targeting drugs are ongoing. The advantages of these agents include long dosing intervals of up to 6 months and the potential to regulate the abundance of any disease-related protein. Long-term safety has yet to be demonstrated in large-scale clinical trials.

Apolipoprotein C-III and cardiovascular diseases: when genetics meet molecular pathologies

Cardiovascular diseases (CVD) have overtaken infectious diseases and are currently the world's top killer. A quite strong linkage between this type of ailments and elevated plasma levels of triglycerides (TG) has been always noticed. Notably, this risk factor is mired in deep confusion, since its role in atherosclerosis is uncertain. One of the explanations that aim to decipher this persistent enigma was provided by apolipoprotein C-III (apoC-III), a small protein historically recognized as an important regulator of TG metabolism. Preeminently, hundreds of studies have been carried out in order to explore the APOC3 genetic background, as well as to establish a correlation between its variants and dyslipidemia-related disorders, pointing to an earnest predictive power for future outcomes. Among several polymorphisms reported within the APOC3, the SstI site in its 3'-untranslated region (3'-UTR) was the most consistently and robustly associated with an increased CVD risk. As more genetic data supporting its importance in cardiovascular events aggregate, it was declared, correspondingly, that apoC-III exerts various atherogenic effects, either by intervening in the function and catabolism of many lipoproteins, or by inducing endothelial inflammation and smooth muscle cells (SMC) proliferation. This review was designed to shed the light on the structural and functional aspects of the APOC3 gene, the existing association between its SstI polymorphism and CVD, and the specific molecular mechanisms that underlie apoC-III pathological implications. In addition, the translation of all these gathered knowledges into preventive and therapeutic benefits will be detailed too.

ApoCIII: A multifaceted protein in cardiometabolic disease

ApoCIII has a well-recognized role in triglyceride-rich lipoproteins metabolism. A considerable amount of data has clearly highlighted that high levels of ApoCIII lead to hypertriglyceridemia and, thereby, may influence the risk of cardiovascular disease. However, recent findings indicate that ApoCIII might also act beyond lipid metabolism. Indeed, ApoCIII has been implicated in other physiological processes such as glucose homeostasis, monocyte adhesion, activation of inflammatory pathways, and modulation of the coagulation cascade. As the inhibition of ApoCIII is emerging as a new promising therapeutic strategy, the complete understanding of multifaceted pathophysiological role of this apoprotein may be relevant. Therefore, the purpose of this work is to review available evidences not only related to genetics and biochemistry of ApoCIII, but also highlighting the role of this apoprotein in triglyceride and glucose metabolism, in the inflammatory process and coagulation cascade as well as in cardiovascular disease.

Relationship of Apolipoproteins with Subclinical Cardiovascular Risk in Youth

OBJECTIVE

To examine the association of apolipoproteins with arterial stiffness and carotid artery structure in children and adolescents.

STUDY DESIGN

A total of 338 children and adolescents (178 female) with a mean age 13.0 ± 2.8 years were examined. Apolipoproteins (AI, AII, B₁₀₀, CII, CIII, and E) were measured via human apolipoprotein magnetic bead panel. Applanation tonometry determined pulse wave velocity and ultrasound imaging measured carotid intima-media thickness. Dual X-ray absorptiometry measured total body fat percent. Linear regression models were adjusted for Tanner stage, sex, and race with further adjustments for body fat percent. Linear regression models also examined the interaction between Tanner stage and apolipoproteins.

RESULTS

There was a significant positive association between pulse wave velocity and apolipoproteins: AI (0.015 m/s/10 μg/mL [CI 0.005-0.026], P = .003), AII (0.036 m/s/10 μg/mL [0.017-0.056], P < .001), B₁₀₀ (0.009 m/s/10 μg/mL [0.002-0.016], P = .012), E (0.158 m/s/10 μg/mL [0.080-0.235], P < .001), and CIII:CII (0.033/μg/mL [0.014-0.052], P < .001). After we added body fat percent to the models, pulse wave velocity (PWV) remained positively associated with greater levels of apolipoproteins: AI, AII, B₁₀₀, E, and CIII:CII. Both with and without the adjustment for body fat percent, there were no significant associations between any apolipoprotein and carotid intima-media thickness. There were no significant interactions between Tanner stage and apolipoproteins.

CONCLUSIONS

These findings suggest that greater levels of apolipoprotein AII, E, and CIII:CII are associated with increased arterial stiffness in children and adolescents, both with and without adjusting for percent body fat. These specific apolipoproteins may be useful as biomarkers of cardiovascular risk.

Omega-3 polyunsaturated fatty acids: anti-inflammatory and anti-hypertriglyceridemia mechanisms in cardiovascular disease

Cardiovascular disease (CVD) is the world's most recognized and notorious cause of death. It is known that increased triglyceride-rich lipoproteins (TRLs) and remnants of triglyceride-rich lipoproteins (RLP) are the major risk factor for CVD. Furthermore, hypertriglyceridemia commonly leads to a reduction in HDL and an increase in atherogenic small dense low-density lipoprotein (sdLDL or LDL-III) levels. Thus, the evidence shows that Ω-3 fatty acids (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have a beneficial effect on CVD through reprogramming of TRL metabolism, reducing inflammatory mediators (cytokines and leukotrienes), and modulation of cell adhesion molecules. Therefore, the purpose of this review is to provide the molecular mechanism related to the beneficial effect of Ω-3 PUFA on the lowering of plasma TAG levels and other atherogenic lipoproteins. Taking this into account, this study also provides the TRL lowering and anti-inflammatory mechanism of Ω-3 PUFA metabolites such as RvE1 and RvD2 as a cardioprotective function.

Protein-Defined Subspecies of HDLs (High-Density Lipoproteins) and Differential Risk of Coronary Heart Disease in 4 Prospective Studies

OBJECTIVE

HDL (high-density lipoprotein) contains functional proteins that define single subspecies, each comprising 1% to 12% of the total HDL. We studied the differential association with coronary heart disease (CHD) of 15 such subspecies. Approach and Results: We measured plasma apoA1 (apolipoprotein A1) concentrations of 15 protein-defined HDL subspecies in 4 US-based prospective studies. Among participants without CVD at baseline, 932 developed CHD during 10 to 25 years. They were matched 1:1 to controls who did not experience CHD. In each cohort, hazard ratios for each subspecies were computed by conditional logistic regression and combined by meta-analysis. Higher levels of HDL subspecies containing alpha-2 macroglobulin, CoC3 (complement C3), HP (haptoglobin), or PLMG (plasminogen) were associated with higher relative risk compared with the HDL counterpart lacking the defining protein (hazard ratio range, 0.96-1.11 per 1 SD increase versus 0.73-0.81, respectively; P for heterogeneity <0.05). In contrast, HDL containing apoC1 or apoE were associated with lower relative risk compared with the counterpart (hazard ratio, 0.74; P=0.002 and 0.77, P=0.001, respectively).

CONCLUSIONS

Several subspecies of HDL defined by single proteins that are involved in thrombosis, inflammation, immunity, and lipid metabolism are found in small fractions of total HDL and are associated with higher relative risk of CHD compared with HDL that lacks the defining protein. In contrast, HDL containing apoC1 or apoE are robustly associated with lower risk. The balance between beneficial and harmful subspecies in a person's HDL sample may determine the risk of CHD pertaining to HDL and paths to treatment.

High-Density Lipoprotein Carries Markers That Track With Recovery From Stroke

RATIONALE

Prospective cohort studies question the value of HDL-C (high-density lipoprotein cholesterol) for stroke risk prediction.

OBJECTIVE

Investigate the relationship between long-term functional recovery and HDL proteome and function.

METHODS AND RESULTS

Changes in HDL protein composition and function (cholesterol efflux capacity) in patients after acute ischemic stroke at 2 time points (24 hours, 35 patients; 96 hours, 20 patients) and in 35 control subjects were measured. The recovery from stroke was assessed by 3 months, the National Institutes of Health Stroke Scale and modified Rankin scale scores. When compared with control subject after adjustments for sex and HDL-C levels, 12 proteins some of which participate in acute phase response and platelet activation (APMAP [adipocyte plasma membrane-associated protein], GPLD1 [phosphate inositol-glycan specific phospholipase D], APOE [apolipoprotein E], IHH [Indian hedgehog protein], ITIH4 [inter-alpha-trypsin inhibitor chain H4], SAA2 [serum amyloid A2], APOA4 [apolipoprotein A-IV], CLU [clusterin], ANTRX2 [anthrax toxin receptor 2], PON1 [serum paraoxonase/arylesterase], SERPINA1 [alpha-1-antitrypsin], and APOF [apolipoprotein F]) were significantly (adjusted P<0.05) altered in stroke HDL at 96 hours. The first 8 of these proteins were also significantly altered at 24 hours. Consistent with inflammatory remodeling, cholesterol efflux capacity was reduced by 32% (P<0.001) at both time points. Baseline stroke severity adjusted regression model showed that changes within 96-hour poststroke in APOF, APOL1, APMAP, APOC4 (apolipoprotein C4), APOM (apolipoprotein M), PCYOX1 (prenylcysteine oxidase 1), PON1, and APOE correlate with stroke recovery scores (R2=0.38-0.73, adjusted P<0.05). APOF (R2=0.73) and APOL1 (R2=0.60) continued to significantly correlate with recovery scores after accounting for tPA (tissue-type plasminogen activator) treatment.

CONCLUSIONS

Changes in HDL proteins during early acute phase of stroke associate with recovery. Monitoring HDL proteins may provide clinical biomarkers that inform on stroke recuperation.

The Positive Association between Plasma Myristic Acid and ApoCIII Concentrations in Cardiovascular Disease Patients Is Supported by the Effects of Myristic Acid in HepG2 Cells

BACKGROUND

In the settings of primary and secondary prevention for coronary artery disease (CAD), a crucial role is played by some key molecules involved in triglyceride (TG) metabolism, such as ApoCIII. Fatty acid (FA) intake is well recognized as a main determinant of plasma lipids, including plasma TG concentration.

OBJECTIVES

The aim was to investigate the possible relations between the intakes of different FAs, estimated by their plasma concentrations, and circulating amounts of ApoCIII.

METHODS

Plasma samples were obtained from 1370 subjects with or without angiographically demonstrated CAD (mean ± SD age: 60.6 ± 11.0 y; males: 75.8%; BMI: 25.9 ± 4.6 kg/m2; CAD: 73.3%). Plasma lipid, ApoCIII, and FA concentrations were measured. Data were analyzed by regression models adjusted for FAs and other potential confounders, such as sex, age, BMI, diabetes, smoking, and lipid-lowering therapies. The in vitro effects of FAs were tested by incubating HepG2 hepatoma cells with increasing concentrations of selected FAs, and the mRNA and protein contents in the cells were quantified by real-time RT-PCR and LC-MS/MS analyses.

RESULTS

Among all the analyzed FAs, myristic acid (14:0) showed the most robust correlations with both TGs (R = 0.441, P = 2.6 × 10-66) and ApoCIII (R = 0.327, P = 1.1 × 10-31). By multiple regression analysis, myristic acid was the best predictor of both plasma TG and ApoCIII variability. Plasma TG and ApoCIII concentrations increased progressively at increasing concentrations of myristic acid, independently of CAD diagnosis and gender. Consistent with these data, in the in vitro experiments, an ∼2-fold increase in the expression levels of the ApoCIII mRNA and protein was observed after incubation with 250 μM myristic acid. A weaker effect (∼30% increase) was observed for palmitic acid, whereas incubation with oleic acid did not affect ApoCIII protein or gene expression.

CONCLUSIONS

Plasma myristic acid is associated with increased ApoCIII concentrations in cardiovascular patients. In vitro experiments indicated that myristic acid stimulates ApoCIII expression in HepG2 cells.

Triglyceride-containing lipoprotein sub-fractions and risk of coronary heart disease and stroke: A prospective analysis in 11,560 adults

AIMS

Elevated low-density lipoprotein cholesterol (LDL-C) is a risk factor for cardiovascular disease; however, there is uncertainty about the role of total triglycerides and the individual triglyceride-containing lipoprotein sub-fractions. We measured 14 triglyceride-containing lipoprotein sub-fractions using nuclear magnetic resonance and examined associations with coronary heart disease and stroke.

METHODS

Triglyceride-containing sub-fraction measures were available in 11,560 participants from the three UK cohorts free of coronary heart disease and stroke at baseline. Multivariable logistic regression was used to estimate the association of each sub-fraction with coronary heart disease and stroke expressed as the odds ratio per standard deviation increment in the corresponding measure.

RESULTS

The 14 triglyceride-containing sub-fractions were positively correlated with one another and with total triglycerides, and inversely correlated with high-density lipoprotein cholesterol (HDL-C). Thirteen sub-fractions were positively associated with coronary heart disease (odds ratio in the range 1.12 to 1.22), with the effect estimates for coronary heart disease being comparable in subgroup analysis of participants with and without type 2 diabetes, and were attenuated after adjustment for HDL-C and LDL-C. There was no evidence for a clear association of any triglyceride lipoprotein sub-fraction with stroke.

CONCLUSIONS

Triglyceride sub-fractions are associated with increased risk of coronary heart disease but not stroke, with attenuation of effects on adjustment for HDL-C and LDL-C.

Distinct Metabolomic Profile Because of Gestational Diabetes and its Treatment Mode in Women with Overweight and Obesity

OBJECTIVE

Whether the presence of gestational diabetes (GDM) and its treatment mode influence the serum metabolic profile in women with overweight or obesity was studied.

METHODS

The serum metabolic profiles of 352 women with overweight or obesity participating in a mother-infant clinical study were analyzed with a targeted NMR approach (at 35.1 median gestational weeks). GDM was diagnosed with a 2-hour 75-g oral glucose tolerance test.

RESULTS

The metabolomic profile of the women with GDM (n = 100) deviated from that of women without GDM (n = 252). Differences were seen in 70 lipid variables, particularly higher concentrations of very low-density lipoprotein particles and serum triglycerides were related to GDM. Furthermore, levels of branched-chain amino acids and glycoprotein acetylation, a marker of low-grade inflammation, were higher in women with GDM. Compared with women with GDM treated with diet only, the women treated with medication (n = 19) had higher concentrations of severalizes of VLDL particles and their components, leucine, and isoleucine, as well as glycoprotein acetylation.

CONCLUSIONS

A clearly distinct metabolic profile was detected in GDM, which deviated even more if the patient was receiving medical treatment. This suggests a need for more intense follow-up and therapy for women with GDM during pregnancy and postpartum to reduce their long-term adverse health risks.

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.

Potential of Chlorella as a Dietary Supplement to Promote Human Health

Chlorella is a green unicellular alga that is commercially produced and distributed worldwide as a dietary supplement. Chlorella products contain numerous nutrients and vitamins, including D and B12, that are absent in plant-derived food sources. Chlorella contains larger amounts of folate and iron than other plant-derived foods. Chlorella supplementation to mammals, including humans, has been reported to exhibit various pharmacological activities, including immunomodulatory, antioxidant, antidiabetic, antihypertensive, and antihyperlipidemic activities. Meta-analysis on the effects of Chlorella supplementation on cardiovascular risk factors have suggested that it improves total cholesterol levels, low-density lipoprotein cholesterol levels, systolic blood pressure, diastolic blood pressure, and fasting blood glucose levels but not triglycerides and high-density lipoprotein cholesterol levels. These beneficial effects of Chlorella might be due to synergism between multiple nutrient and antioxidant compounds. However, information regarding the bioactive compounds in Chlorella is limited.

GlycA, a novel marker for low grade inflammation, reflects gut microbiome diversity and is more accurate than high sensitive CRP in reflecting metabolomic profile

INTRODUCTION

Gut microbiota is, along with adipose tissue, recognized as a source for many metabolic and inflammatory disturbances that may contribute to the individual's state of health.

OBJECTIVES

We investigated in cross-sectional setting the feasibility of utilizing GlycA, a novel low grade inflammatory marker, and traditional low grade inflammatory marker, high sensitivity CRP (hsCRP), in reflecting serum metabolomics status and gut microbiome diversity.

METHODS

Fasting serum samples of overweight/obese pregnant women (n = 335, gestational weeks: mean 13.8) were analysed for hsCRP by immunoassay, GlycA and metabolomics status by NMR metabolomics and faecal samples for gut microbiome diversity by metagenomics. The benefits of GlycA as a metabolic marker were investigated against hsCRP.

RESULTS

The GlycA concentration correlated with more of the metabolomics markers (144 out of 157), than hsCRP (55 out of 157) (FDR < 0.05). The results remained essentially the same when potential confounding factors known to associate with GlycA and hsCRP levels were taken into account (P < 0.05). This was attributable to the detected correlations between GlycA and the constituents and concentrations of several sized VLDL-particles and branched chain amino acids, which were statistically non-significant with regard to hsCRP. GlycA, but not hsCRP, correlated inversely with gut microbiome diversity.

CONCLUSION

GlycA is a superior marker than hsCRP in assessing the metabolomic profile and gut microbiome diversity. It is proposed that GlycA may act as a novel marker that reflects both the gut microbiome and adipose tissue originated metabolic aberrations; this proposal will need to be verified with regard to clinical outcomes.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT01922791, August 14, 2013.

Apolipoprotein CIII predicts cardiovascular events in patients with coronary artery disease: a prospective observational study

Background

Apolipoprotein CIII (apoCIII) is associated with triglyceride-rich lipoprotein metabolism and has emerged as independent marker for risk of cardiovascular disease. The objective was to test whether apoCIII is regulated postprandially and whether apoCIII concentrations in native and chylomicron-free serum predict future cardiovascular events in patients with stable coronary artery disease (CAD).

Methods

ApoCIII concentrations were measured in native and chylomicron-free serum in the fasting state and after a standardized oral fat load test in 195 patients with stable CAD. Clinical follow-up was 48 months. Chylomicron-free serum was prepared by ultracentrifugation (18,000 rpm, 3 h). The log-rank test and Cox regression analyses were used to investigate the association of apoCIII with recurrent cardiovascular events.

Results

Of the 195 patients included, 92 had a cardiovascular event, and 103 did not. 97% were treated with a statin. No significant changes in apoCIII concentration were observed after the oral fat load test. The apoCIII concentration was associated with event-free survival independent of conventional risk factors. This association reached statistical significance only for apoCIII concentration measured in chylomicron-free serum (hazard ratio [95% confidence interval] for apoCIII above the mean: postprandial: 1.67 (1.06–2.29), P = 0.028, fasting: 2.09 (1.32–3.32), P = 0.002), but not for apoCIII concentration measured in native serum (postprandial: 1.47 [0.89–2.43], P = 0.133, fasting: 1.56 [0.95–2.58], P = 0.081). The effects were independent of other risk factors.

Conclusions

ApoCIII concentrations in chylomicron-free serum are independently associated with event-free survival in patients with CAD both in fasting and postprandial state. This findings support considering apoCIII for risk assessment and attempting to test the hypothesis that lowering apoCIII reduces residual cardiovascular risk.

Take home message

Apolipoprotein CIII concentration measured in chylomicron-free serum predicts recurrent cardiovascular events in patients with stable coronary artery disease.

Trial registration

The trial which included the participants of this study was registered at https://clinicaltrials.gov (NCT00628524) on March 5, 2008.

High-frequency metabolite profiling and the incidence of recurrent cardiac events in patients with post-acute coronary syndrome

Purpose: The aim of this study was to study temporal changes in metabolite profiles in patients with post-acute coronary syndrome (ACS), in particular prior to the development of recurrent ACS (reACS).Methods: BIOMArCS (BIOMarker study to identify the Acute risk of a Coronary Syndrome) is a prospective study including patients admitted for ACS, who underwent high-frequency blood sampling during 1-year follow-up. Within BIOMArCS, we performed a nested case-cohort analysis of 158 patients (28 cases of reACS). We determined 151 metabolites by nuclear magnetic resonance in seven (median) blood samples per patient. Temporal evolution of the metabolites and their relation with reACS was assessed by joint modelling. Results are reported as adjusted (for clinical factors) hazard ratios (aHRs).Results: Median age was 64 (25th-75th percentiles; 56-72) years and 78% were men. After multiple testing correction (p < 0.001), high concentrations of extremely large very low density lipoprotein (VLDL) particles (aHR 1.60/SD increase; 95%CI 1.25-2.08), very large VLDL particles (aHR 1.60/SD increase; 95%CI 1.25-2.08) and large VLDL particles (aHR 1.56/SD increase; 95%CI 1.22-2.05) were significantly associated with reACS. Moreover, these longitudinal particle concentrations showed a steady increase over time prior to reACS. Among the other metabolites, no significant associations were observed.Conclusion: Post-ACS patients with persistent high concentrations of extremely large, very large and large VLDL particles have increased risk of reACS within 1 year.

Comparison of the Efficacy and Safety of Rosuvastatin/Ezetimibe Combination Therapy and Rosuvastatin Monotherapy on Lipoprotein in Patients With Type 2 Diabetes: Multicenter Randomized Controlled Study

INTRODUCTION

Ezetimibe/statin combination therapy has been reported to provide additional cardioprotective effects compared to statin monotherapy. The apolipoprotein B/A1 (apoB/A1) ratio is an effective predictor of cardiovascular diseases. The aim of this study was to compare the efficacy and safety of rosuvastatin/ezetimibe combination therapy versus rosuvastatin monotherapy using the apoB/A1 ratio in patients with diabetes and hypercholesterolemia.

METHODS

In this randomized, multicenter, open-label, parallel-group study, patients were randomly assigned to receive the combination therapy of rosuvastatin 5 mg/ezetimibe 10 mg once daily (n = 68) or monotherapy with rosuvastatin 10 mg once daily (n = 68), for 8 weeks.

RESULTS

After the 8-week treatment, percentage change (least-square means ± standard error) in the apoB/A1 ratio in the rosuvastatin/ezetimibe group was significantly decreased compared to the rosuvastatin group (- 46.14 ± 1.58% vs.  - 41.30 ± 1.58%, respectively; P = 0.03). In addition, the proportion of patients achieving > 50% reduction in low-density lipoprotein-cholesterol (LDL-C) and in the comprehensive lipid target (LDL-C < 70 mg/dL, non-HDL-cholesterol [non-HDL-C] < 100 mg/dL, and apoB < 80 mg/dL) was significantly different between the two groups (76.5 and 73.5% in the rosuvastatin/ezetimibe group and 47.1 and 45.6% in the rosuvastatin group, respectively; P < 0.001). The reduction in total cholesterol, non-HDL-C, LDL-C, and apoB were greater in the rosuvastatin/ezetimibe group than in the rosuvastatin group. Both treatments were well tolerated, and no between-group differences in drug-related adverse events were observed.

CONCLUSION

The apoB/A1 ratio was significantly reduced in patients receiving combination therapy with ezetimibe and rosuvastatin compared to those receiving rosuvastatin monotherapy. Both treatments were well tolerated in patients with type 2 diabetes and hypercholesterolemia.

TRIAL REGISTRATION

NCT03446261.

Triglycerides and Cardiovascular Outcomes-Can We REDUCE-IT ?

The causal linkage between triglycerides and coronary artery disease has been controversial. Most of the trials hitherto have shown marginal or no beneficial effects of reduction of triglycerides (with fibrates) on top of low-density lipoprotein (LDL) reduction. But a significant residual cardiovascular risk remains even after use of high dose of statins. Omega-3 fatty acids have been shown to reduce triglyceride levels and some old trials have shown the benefits of fish oils in reducing cardiovascular events. However, barring a few trials most of the large trials of omega-3 fatty acids are negative. Recently, few large trials have been conducted to see the effects of high dose omega-3 fatty acids on cardiovascular outcomes and some of them have shown promising results on top of LDL reduction.

Triglycerides and Cardiovascular Outcomes-Can We REDUCE-IT ?

The causal linkage between triglycerides and coronary artery disease has been controversial. Most of the trials hitherto have shown marginal or no beneficial effects of reduction of triglycerides (with fibrates) on top of low-density lipoprotein (LDL) reduction. But a significant residual cardiovascular risk remains even after use of high dose of statins. Omega-3 fatty acids have been shown to reduce triglyceride levels and some old trials have shown the benefits of fish oils in reducing cardiovascular events. However, barring a few trials most of the large trials of omega-3 fatty acids are negative. Recently, few large trials have been conducted to see the effects of high dose omega-3 fatty acids on cardiovascular outcomes and some of them have shown promising results on top of LDL reduction.

Proteomics analysis of potential serum biomarkers for insulin resistance in patients with polycystic ovary syndrome

The aim of the present study was to identify potential serum biomarkers for insulin resistance (IR) in patients with polycystic ovary syndrome (PCOS) by comparing the differences in serum protein expression levels between PCOS patients with and without IR. PCOS patients aged from 18 to 35 years were recruited at Guangdong Women and Children’s Hospital from January, 2013 to February, 2014. A total of 218 PCOS patients were enrolled and divided into the insulin resistance (PCOS-IR) and non-insulin resistance (PCOS-NIR) groups according to their homeostasis model assessment of insulin resistance. Two-dimensional difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS/MS) techniques were used to identify differences in protein expression levels between the PCOS-IR and PCOS-NIR groups. The present study demonstrated that the total cholesterol (TCH), triglycerides (TG), low-density lipoprotein (LDL), fasting plasma glucose (FPG), 3-h blood glucose (3hBG) and uric acid (UA) levels in the PCOS-IR group were higher than those in the PCOS-NIR group (P<0.05). Between the PCOS-IR and PCOS-NIR groups, a total of 20 differentially expressed protein spots were detected by 2D-DIGE. Among these, 4 proteins, namely afamin, serotransferrin, complement C3 and apolipoprotein C3 (APOC3), were also identified by MALDI-TOF-MS/MS. The alteration of APOC3 was further confirmed by western blot analysis and enzyme-linked immunosorbent assay (ELISA). The present study also confirmed that the expression level of APOC3 was positively associated with the homeostasis model assessment of insulin resistance (HOMA-IR). On the whole, the data indicate that APOC3 may be a potential diagnostic marker for PCOS-IR patients.