New approaches to address dyslipidemia

Untargeted Lipidomic Profiling Reveals Lysophosphatidylcholine and Ceramide as Atherosclerotic Risk Factors in apolipoprotein E Knockout Mice

Despite the availability and use of numerous cholesterol-lowering drugs, atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of mortality globally. Many researchers have focused their effort on identifying modified lipoproteins. However, lipid moieties such as lysophosphatidylcholine (LPC) and ceramide (CER) contribute to atherogenic events. LPC and CER both cause endothelial mitochondrial dysfunction, leading to fatty acid and triglyceride (TG) accumulation. In addition, they cause immune cells to differentiate into proinflammatory phenotypes. To uncover alternative therapeutic approaches other than cholesterol- and TG-lowering medications, we conducted untargeted lipidomic investigations to assess the alteration of lipid profiles in apolipoprotein E knockout (apoE^-/-) mouse model, with or without feeding a high-fat diet (HFD). Results indicated that, in addition to hypercholesterolemia and hyperlipidemia, LPC levels were two to four times higher in apoE^-/- mice compared to wild-type mice in C57BL/6 background, regardless of whether they were 8 or 16 weeks old. Sphingomyelin (SM) and CER were elevated three- to five-fold in apoE^-/- mice both at the basal level and after 16 weeks when compared to wild-type mice. After HFD treatment, the difference in CER levels elevated more than ten-fold. Considering the atherogenic properties of LPC and CER, they may also contribute to the early onset of atherosclerosis in apoE^-/- mice. In summary, the HFD-fed apoE^-/- mouse shows elevated LPC and CER contents and is a suitable model for developing LPC- and CER-lowering therapies.

Recent Update on the Development of PCSK9 Inhibitors for Hypercholesterolemia Treatment

The proprotein convertase subtilisin/kexin-type 9 (PCSK9) binds to low-density lipoprotein receptors (LDLR), thereby trafficking them to lysosomes upon endocytosis and enhancing intracellular degradation to prevent their recycling. As a result, the levels of circulating LDL cholesterol (LDL-C) increase, which is a prominent risk factor for developing atherosclerotic cardiovascular diseases (ASCVD). Thus, PCSK9 has become a promising therapeutic target that offers a fertile testing ground for new drug modalities to regulate plasma LDL-C levels to prevent ASCVD. In this review, we have discussed the role of PCSK9 in lipid metabolism and briefly summarized the current clinical status of modalities targeting PCSK9. In particular, a detailed overview of peptide-based PCSK9 inhibitors is presented, which emphasizes their structural features and design, therapeutic effects on patients, and preclinical cardiovascular disease (CVD) models, along with PCSK9 modulation mechanisms. As a promising alternative to monoclonal antibodies (mAbs) for managing LDL-C, anti-PCSK9 peptides are emerging as a prospective next generation therapy.

Angiopoietin-Like Protein 3 (ANGPTL3) Modulates Lipoprotein Metabolism and Dyslipidemia

Dyslipidemia is characterized by increasing plasma levels of low-density lipoprotein-cholesterol (LDL-C), triglycerides (TGs) and TG-rich lipoproteins (TGRLs) and is a major risk factor for the development of atherosclerotic cardiovascular disorders (ASCVDs). It is important to understand the metabolic mechanisms underlying dyslipidemia to develop effective strategies against ASCVDs. Angiopoietin-like 3 (ANGPTL3), a member of the angiopoietin-like protein family exclusively synthesized in the liver, has been demonstrated to be a critical regulator of lipoprotein metabolism to inhibit lipoprotein lipase (LPL) activity. Genetic, biochemical, and clinical studies in animals and humans have shown that loss of function, inactivation, or downregulated expression of ANGPTL3 is associated with an obvious reduction in plasma levels of TGs, LDL-C, and high-density lipoprotein-cholesterol (HDL-C), atherosclerotic lesions, and the risk of cardiovascular events. Therefore, ANGPTL3 is considered an alternative target for lipid-lowering therapy. Emerging studies have focused on ANGPTL3 inhibition via antisense oligonucleotides (ASOs) and monoclonal antibody-based therapies, which have been carried out in mouse or monkey models and in human clinical studies for the management of dyslipidemia and ASCVDs. This review will summarize the current literature on the important role of ANGPTL3 in controlling lipoprotein metabolism and dyslipidemia, with an emphasis on anti-ANGPTL3 therapies as a potential strategy for the treatment of dyslipidemia and ASCVDs.

Serum Apolipoprotein A-I Predicts Response of Rectal Cancer to Neoadjuvant Chemoradiotherapy

Background

Serum lipids have been reported as prognosticators for malignancies, including rectal cancer (RC). Yet, their value in predicting the response of RC to neoadjuvant chemoradiotherapy (NACRT) remains unknown. This study aimed to assess the predictive abilities of serum lipids for a bad response, and to build a serum lipid-based prediction model.

Methods

In total, 751 patients diagnosed with stage cII–III RC and treated with NACRT plus surgery from January 2007 to August 2018 were retrospectively reviewed and randomly divided into two data sets, in a ratio of 1:1. Receiver operating characteristics (ROC) analysis was conducted in the development set to select possible predictors of bad NACRT response from pathoclinical factors, including serum lipids. Multivariate logistic regression was conducted to further determine independent predictors, which were then used to develop a prediction index (PI). Finally, the PI was verified in the validation set, through ROC analysis and chi-squared test.

Results

Five independent predictors were identified: tumor length ≥4 cm, cT4 stage, carcinoembryonic antigen ≥5.0 ng/mL, irradiation with three-dimensional conformal radiotherapy technique, and apolipoprotein A-I ≤1.20 g/L. Each of them was assigned a number of points. In the validation set, the area under the curve of PI appeared as 0.642 (95% confidence interval 0.586–0.697). The sensitivity, specificity, positive and negative predictive values, and concordance were 72.3%, 52.3%, 63.8%, 61.9%, and 63.0%, respectively.

Conclusion

Serum apolipoprotein A-I was found to correlate negatively with the RC response to NACRT. It could serve as a biomarker for guiding individualized treatment and a potential target for improving sensitivity to chemoradiation.

Cholesterol Metabolites 25-Hydroxycholesterol and 25-Hydroxycholesterol 3-Sulfate Are Potent Paired Regulators: From Discovery to Clinical Usage

Oxysterols have long been believed to be ligands of nuclear receptors such as liver × receptor (LXR), and they play an important role in lipid homeostasis and in the immune system, where they are involved in both transcriptional and posttranscriptional mechanisms. However, they are increasingly associated with a wide variety of other, sometimes surprising, cell functions. Oxysterols have also been implicated in several diseases such as metabolic syndrome. Oxysterols can be sulfated, and the sulfated oxysterols act in different directions: they decrease lipid biosynthesis, suppress inflammatory responses, and promote cell survival. Our recent reports have shown that oxysterol and oxysterol sulfates are paired epigenetic regulators, agonists, and antagonists of DNA methyltransferases, indicating that their function of global regulation is through epigenetic modification. In this review, we explore our latest research of 25-hydroxycholesterol and 25-hydroxycholesterol 3-sulfate in a novel regulatory mechanism and evaluate the current evidence for these roles.

Effects of Chemotherapy on Serum Lipids in Chinese Postoperative Breast Cancer Patients

Purpose

Chemotherapy is a comprehensive therapy for breast cancer; nevertheless, its associated adverse effects are drawing increasing attention with the continuous improvement of the efficacy. The changes in serum lipids of breast cancer patients caused by chemotherapy have been reported by previous studies, whereby the former increase the incidence rate of cardiovascular disorders. However, the variations in the changes of serum lipids with different chemotherapy regimens have seldom been reported.

Methods

From January 2011 to December 2017, 1740 breast cancer patients treated with chemotherapy were recruited at the First Affiliated Hospital of Nanjing Medical University. The chemotherapy regimens included anthracycline-based, taxane-based, and anthracycline-plus-taxane-based regimens, dose-dense and standard-interval regimens. Lipid profiles that contained TG (triglyceride), TC (total cholesterol), HDL-C (high-density lipoprotein cholesterol), LDL-C (low-density lipoprotein cholesterol) and Lpa (lipoprotein a) levels were collected prior to the first, second and last cycles of chemotherapy. The changes of serum lipids with the same or different chemotherapy regimens were analyzed and compared.

Results

It was observed that the levels of TG, TC, LDL-C and Lpa increased significantly while that of HDL-C decreased after adjuvant chemotherapy in breast cancer patients (P<0.05). Besides, dose-dense regimens had more influence in TG and HDL-C and less influence in TC and LDL-C than standard-interval regimens. HDL-C was more sensitive to anthracycline-based regimens than taxane-based regimens. The level of TG with anthracycline-plus-taxane-based regimens was higher than that with only anthracycline-based or taxane-based regimens, and the level of HDL-C with anthracycline-plus-taxane-based regimen showed lower than that with taxane-based regimen.

Conclusion

In summary, this study proposed that dyslipidemia was strongly associated with chemotherapy in Chinese breast cancer patients after operative treatment. Furthermore, the changes in levels of serum lipids varied among patients with different chemotherapy regimens and taxane had less effect on dyslipidemia than anthracycline.

The Diagnosis and Treatment of Hypertriglyceridemia

BACKGROUND

Hypertriglyceridemia affects 15-20% of the adult population and is associated with overweight, metabolic syndrome, and diabetes mellitus. It is often discovered incidentally.

METHODS

This review is based on pertinent publications retrieved by a selective literature search, including current guidelines on hypertriglyceridemia.

RESULTS

Elevated triglyceride (TG) levels are causally linked to cardiovascular disease; TG levels above 1000 mg/dL (11.4 mmol/L) can induce acute pancreatitis. The individual risk of cardiovascular disease and of pancreatitis must be estimated in order to decide whether, and how, hypertriglyceridemia should be treated. Lifestyle modifications (cessation of alcohol consumption, reduced intake of rapidly metabolized carbohydrates), weight loss, and blood sugar control are the most effective ways to lower TG levels. The need to lower the low-density lipoprotein (LDL) concentration must be determined on the basis of the cardiovascular risk, independently of the success of the lifestyle changes. Few patients need specific drug treatment to lower the TG level. Fibrates can lower TG concentrations, but their efficacy in combination with statins has not been clearly shown in endpoint studies. A daily dose of 2-4 g omega-3 fatty acids can also lower TG levels. To date, only a single large-scale randomized, blinded trial has shown the efficacy of 4 g of eicosapentaenoic acid ethyl ester per day in lowering the risk in high-risk patients (number needed to treat = 21). Patients with the very rare purely genetic types of hypertriglyceridemia (familial chylomicronemia syndrome) should be treated in specialized outpatient clinics.

CONCLUSION

Hypertriglyceridemia is causally linked to cardiovascular disease and pancreatitis. Lifestyle modifications play a paramount role in its treatment.

Pharmacokinetics of current and emerging treatments for hypercholesterolemia

Introduction: Reduction of low-density-lipoprotein cholesterol (LDL-C) and other apolipoprotein B (apoB)-containing lipoproteins reduces cardiovascular (CV) events and greater reductions have greater benefits. Current lipid treatments cannot always achieve desirable LDL-C targets and additional or alternative treatments are often needed.Areas covered: In this article, we review the pharmacokinetics of the available and emerging treatments for hypercholesterolemia and focus on recently approved drugs and those at a late stage of development.Expert opinion: Statin pharmacokinetics are well known and appropriate drugs and doses can usually be chosen for individual patients to achieve LDL-C targets and avoid adverse effects and drug-drug interactions. Ezetimibe, icosapent ethyl and the monoclonal antibodies evolocumab and alirocumab have established efficacy and safety. Newer oral agents including pemafibrate and bempedoic acid have generally favorable pharmacokinetics supporting use in a wide range of patients. RNA-based therapies with antisense oligonucleotides are highly specific for their targets and those inhibiting apoB, apoCIII, angiopoietin-like protein 3 and lipoprotein(a) have shown promising results. The small-interfering RNA inclisiran has the notable advantage that a single subcutaneous administration may be effective for up to 6 months. The CV outcome trial results and long term safety data are eagerly awaited for these new agents.

Metabolomic Signature of Angiopoietin-Like Protein 3 Deficiency in Fasting and Postprandial State

Objective- Loss-of-function (LOF) variants in the ANGPTL3 (angiopoietin-like protein 3) have been associated with low levels of plasma lipoproteins and decreased coronary artery disease risk. We aimed to determine detailed metabolic effects of genetically induced ANGPTL3 deficiency in fasting and postprandial state. Approach and Results- We studied individuals carrying S17X LOF mutation in ANGPTL3 (6 homozygous and 32 heterozygous carriers) and 38 noncarriers. Nuclear magnetic resonance metabolomics was used to quantify 225 circulating metabolic measures. We compared metabolic differences between LOF carriers and noncarriers in fasting state and after a high-fat meal. In fasting, ANGPTL3 deficiency was characterized by similar extent of reductions in LDL (low-density lipoprotein) cholesterol (0.74 SD units lower concentration per LOF allele [95% CI, 0.42-1.06]) as observed for many TRL (triglyceride-rich lipoprotein) measures, including VLDL (very-low-density lipoprotein) cholesterol (0.75 [95% CI, 0.45-1.05]). Within most lipoprotein subclasses, absolute levels of cholesterol were decreased more than triglycerides, resulting in the relative proportion of cholesterol being reduced within TRLs and their remnants. Further, β-hydroxybutyrate was elevated (0.55 [95% CI, 0.21-0.89]). Homozygous ANGPTL3 LOF carriers showed essentially no postprandial increase in TRLs and fatty acids, without evidence for adverse compensatory metabolic effects. Conclusions- In addition to overall triglyceride- and LDL cholesterol-lowering effects, ANGPTL3 deficiency results in reduction of cholesterol proportion within TRLs and their remnants. Further, ANGPTL3 LOF carriers had elevated ketone body production, suggesting enhanced hepatic fatty acid β-oxidation. The detailed metabolic profile in human knockouts of ANGPTL3 reinforces inactivation of ANGPTL3 as a promising therapeutic target for decreasing cardiovascular risk.

Current Role of Lipoprotein Apheresis

Purpose of Review

Lipoprotein apheresis is a very efficient but time-consuming and expensive method of lowering levels of low-density lipoprotein cholesterol, lipoprotein(a)) and other apoB containing lipoproteins, including triglyceride-rich lipoproteins. First introduced almost 45 years ago, it has long been a therapy of “last resort” for dyslipidaemias that cannot otherwise be managed. In recent years new, very potent lipid-lowering drugs have been developed and the purpose of this review is to define the role of lipoprotein apheresis in the current setting.

Recent Findings

Lipoprotein apheresis still plays an important role in managing patients with homozygous FH and some patients with other forms of hypercholesterolaemia and cardiovascular disease. In particular, patients not achieving treatment goals despite modern lipid-lowering drugs, either because these are not tolerated or the response is insufficient. Recently, lipoprotein(a) has emerged as an important cardiovascular risk factor and lipoprotein apheresis has been used to decrease lipoprotein(a) concentrations in patients with marked elevations and cardiovascular disease. However, there is considerable heterogeneity concerning the recommendations by scientific bodies as to which patient groups should be treated with lipoprotein apheresis.

Summary

Lipoprotein apheresis remains an important tool for the management of patients with severe drug-resistant dyslipidaemias, especially those with homozygous FH.

Determinants of Achieved LDL Cholesterol and "Non-HDL" Cholesterol in the Management of Dyslipidemias

PURPOSE OF REVIEW

The advent of combination therapy to provide LDL lowering beyond that achieved with statins necessitates the development of greater understanding of how drugs work together, what changes occur in key lipoprotein fractions, and what residual risk remains.

RECENT FINDINGS

Clinical trials of agents that, when added to statins, generate profound LDL lowering have been successful in reducing further the risk of cardiovascular disease. LDL cholesterol can be now decreased to unprecedented levels, so the focus of attention then shifts to other apolipoprotein B-containing, atherogenic lipoprotein classes such as lipoprotein(a) and remnants of the metabolism of triglyceride-rich particles. "Non-HDL cholesterol" is used increasingly (especially if measured in the non-fasting state) as a more comprehensive index of risk. Metabolic studies reveal how current drugs act in combination to achieve profound lipid lowering. However, care is needed in interpreting achieved LDLc and non-HDLc levels in the emerging treatment paradigm.

New medications targeting triglyceride-rich lipoproteins: Can inhibition of ANGPTL3 or apoC-III reduce the residual cardiovascular risk?

Remarkably good results have been achieved in the treatment of atherosclerotic cardiovascular diseases (CVD) by using statin, ezetimibe, antihypertensive, antithrombotic, and PCSK9 inhibitor therapies and their proper combinations. However, despite this success, the remaining CVD risk is still high. To target this residual risk and to treat patients who are statin-intolerant or have an exceptionally high CVD risk for instance due to familial hypercholesterolemia (FH), new therapies are intensively sought. One pathway of drug development is targeting the circulating triglyceride-rich lipoproteins (TRL) and their lipolytic remnants, which, according to the current view, confer a major CVD risk. Angiopoietin-like protein 3 (ANGPTL3) and apolipoprotein C-III (apoC-III) are at present the central molecular targets for therapies designed to reduce TRL, and there are new drugs emerging that suppress their expression or inhibit the function of these two key proteins. The medications targeting these components are biological, either human monoclonal antibodies or antisense oligonucleotides. In this article, we briefly review the mechanisms of action of ANGPTL3 and apoC-III, the reasons why they have been considered promising targets of novel therapies for CVD, as well as the current status and the most important results of their clinical trials.

LDL cholesterol: How low to go?

Epidemiology and the results of large-scale outcome trials indicate that the association of LDL with atherosclerotic cardiovascular disease is causal, and continuous not only across levels seen in the general population but also down to sub-physiological values. There is no scientific basis, therefore, to set a target or 'floor' for LDL cholesterol lowering, and this presents a clinical and conceptual dilemma for prescribers, patients, and payers. With the advent of powerful agents such as proprotein convertase/subtilisin kexin type 9 (PCSK9) inhibitors, LDL cholesterol can be lowered profoundly but health economic constraints mandate that this therapeutic approach needs to be selective. Based on the need to maximize the absolute risk reduction when prescribing combination lipid-lowering therapy, it is appropriate to prioritize patients with the highest risk (aggressive and established CVD) who will obtain the highest benefit, that is, those with elevated LDL cholesterol on optimized statin therapy.