Triglyceride-rich remnant lipoproteins are more atherogenic than LDL per particle: is this important?

Exploring emerging pharmacotherapies for type 2 diabetes patients with hypertriglyceridemia

INTRODUCTION

Atherogenic dyslipidaemia with increased triglycerides, low high-density lipoprotein cholesterol levels and increased small dense low-density lipoprotein (LDL) particles is a major risk factor contributing to the increased cardiovascular (CV) risk in patients with type 2 diabetes (T2D). This is regarded as a residual risk after achieving target levels of LDL cholesterol.

AREAS COVERED

This article reviews the novel therapies to reduce triglycerides in patients with T2D. These were identified by a PubMed search and mainly focus on pemafibrate and the drugs targeting apolipoprotein C3 (apoC3) and angiopoietin-like 3 (ANGPTL3).

EXPERT OPINION

Current therapies to reduce triglycerides in patients with T2D include fibrates and omega-3 fatty acids but these are often not sufficient and the evidence for CV benefits is limited. Pemafibrate was effective in reducing triglycerides in patients with T2D but did not reduce CV events in the PROMINENT study. Inhibitors of apoC3 are effective in reducing triglycerides even in familial chylomicronaemia syndrome and olezarsen and plozasiran in this group are being studied in patients with combined hyperlipidemia. The ANGPTL3 inhibitor evinacumab has been approved for homozygous familial hypercholesterolemia and other ANGPTL3 inhibitors may prove be useful to reduce triglycerides in T2D.

Impact of Remnant Cholesterol on Cardiovascular Risk in Diabetes

PURPOSE OF REVIEW

Individuals with diabetes face increased risk of atherosclerotic cardiovascular disease (ASCVD), in part due to hyperlipidemia. Even after LDL cholesterol-lowering, residual ASCVD risk persists, part of which may be attributed to elevated remnant cholesterol. We describe the impact of elevated remnant cholesterol on ASCVD risk in diabetes.

RECENT FINDINGS

Preclinical, observational, and Mendelian randomization studies robustly suggest that elevated remnant cholesterol causally increases risk of ASCVD, suggesting remnant cholesterol could be a treatment target. However, the results of recent clinical trials of omega-3 fatty acids and fibrates, which lower levels of remnant cholesterol in individuals with diabetes, are conflicting in terms of ASCVD prevention. This is likely partly due to neutral effects of these drugs on the total level of apolipoprotein B(apoB)-containing lipoproteins. Elevated remnant cholesterol remains a likely cause of ASCVD in diabetes. Remnant cholesterol-lowering therapies should also lower apoB levels to reduce risk of ASCVD.

Recent Advances in Targeted Management of Inflammation In Atherosclerosis: A Narrative Review

Atherosclerotic cardiovascular disease (ASCVD) remains a leading cause of morbidity and mortality despite effective low-density lipoprotein cholesterol-targeted therapies. This review explores the crucial role of inflammation in the residual risk of ASCVD, emphasizing its impact on atherosclerosis progression and plaque stability. Evidence suggests that high-sensitivity C-reactive protein (hsCRP), and potentially other inflammatory biomarkers, can be used to identify the inflammatory residual ASCVD risk phenotype and may serve as future targets for the development of more efficacious therapeutic approaches. We review the biological basis for the association of inflammation with ASCVD, propose new therapeutic strategies for the use of inflammation-targeted treatments, and discuss current challenges in the implementation of this new treatment paradigm for ASCVD.

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.

Remnant cholesterol as a residual risk in atherosclerotic cardiovascular disease patients under statin-based lipid-lowering therapy: A post hoc analysis of the RACING trial

BACKGROUND

Remnant cholesterol (remnant-C) levels during lipid-lowering therapy (LLT) may indicate residual risk.

OBJECTIVE

We aimed to investigate the clinical outcomes based on on-treatment remnant-C distribution in patients with atherosclerotic cardiovascular disease (ASCVD) under statin-based LLT.

METHODS

In this post hoc analysis of the RACING trial, 3,348 ASCVD patients with lipid profiles 1 year after randomization were investigated. Remnant-C was calculated as total cholesterol minus low-density lipoprotein cholesterol (LDL-C) minus high-density lipoprotein cholesterol. The primary endpoint was a 3-year composite of cardiovascular death, major cardiovascular events, or non-fatal stroke.

RESULTS

The study population was grouped into tertiles according to on-treatment remnant-C: high (> 20.5 mg/dL; n = 1,116), intermediate (14‒20.5 mg/dL; n = 1,031), and low (≤14.0 mg/dL; n = 1,201) remnant-C groups. The high remnant-C group showed the highest incidence of the primary endpoint at 3 years (11.0 %, 10.3 %, and 7.5 % in the high, intermediate, and low remnant-C groups, respectively; p = 0.009). The high remnant-C levels at 1 year were independently associated with an increased risk of the primary outcome, whereas achieving LDL-C <55 or 70 mg/dL was not associated with the incidence of the primary endpoint. The on-treatment remnant-C cut-off of 17 mg/dL (median) demonstrated the ability to discriminate between patients at higher and lower risks for the primary endpoints (hazard ratio: 1.42; 95 % confidence interval: 1.14‒1.78; p = 0.002).

CONCLUSIONS

In patients with ASCVD undergoing statin-based LLT, high on-treatment remnant-C values were associated with unfavorable clinical outcomes. On-treatment remnant-C levels may serve as an additional means of assessing residual cardiovascular risk.

CLINICAL TRIAL REGISTRATION

ClinicalTrials. gov ID: NCT03044665.

Remnant cholesterol, LDL cholesterol, and apoB absolute mass changes explain results of the PROMINENT trial

BACKGROUND AND AIMS

The PROMINENT trial, a cardiovascular outcome trial of the triglyceride- and remnant cholesterol-lowering agent pemafibrate, has shown neutral results despite reduction in plasma triglycerides and remnant cholesterol. We tested the hypothesis that absolute mass changes in remnant cholesterol, LDL cholesterol, and apolipoprotein B explain the results of the PROMINENT trial.

METHODS

Among 108,431 individuals from the Copenhagen General Population Study (CGPS), those who met the key inclusion criteria of the PROMINENT trial were analyzed to mimic the trial design. Endpoint atherosclerotic cardiovascular disease (ASCVD) was cardiovascular death, myocardial infarction, ischemic stroke, and coronary revascularization as defined in PROMINENT.

RESULTS

In the PROMINENT trial, treatment with pemafibrate resulted in -7 mg/dL (-0.18 mmol/L; -18 %) change in remnant cholesterol, +10 mg/dL (+0.26 mmol/L; +12 %) LDL cholesterol, and +5 mg/dL (+0.05 g/L; +5 %) apolipoprotein B. In the CGPS mimicking PROMINENT, the estimated hazard ratios for ASCVD were 0.97 (95 % confidence interval: 0.94-0.99) for a -7 mg/dL (-0.18 mmol/L) change in remnant cholesterol, 1.04 (1.01-1.07) for a +10 mg/dL (+0.26 mmol/L) change in LDL cholesterol, and 1.02 (1.01-1.03) for a +5 mg/dL (+0.05 g/L) change in apolipoprotein B. When combining absolute changes in remnant cholesterol, LDL cholesterol, and apolipoprotein B, the estimated hazard ratio for ASCVD was 1.05 (0.96-1.14) in the CGPS mimicking PROMINENT compared to 1.03 (0.91-1.15) in the PROMINENT trial.

CONCLUSIONS

Absolute mass changes in remnant cholesterol, LDL cholesterol, and apolipoprotein B can explain results of the PROMINENT trial. The 3 mg/dL (0.08 mmol/L) higher total atherogenic cholesterol together with 5 mg/dL (0.05 g/L) higher apolipoprotein B seem to explain the trend toward more ASCVD in the pemafibrate arm.

Distribution of triglyceride-rich lipoproteins and their remnants and their contribution to cardiovascular risk in the Mexican population

BACKGROUND AND AIMS

In recent years, scientific interest in triglyceride-rich lipoproteins (TRL) and remnant cholesterol has increased, focusing on the evidence that these lipoproteins are a causal factor for developing atherosclerotic cardiovascular disease (ASCVD). Furthermore, a high remnant concentration (>38 mg/dL) has been associated with several non-cardiovascular risks. We aimed in this study to describe the percentile distribution of remnant cholesterol. Additionally, we evaluated the association between remnant cholesterol plasma concentration and epidemiologically relevant cardio-metabolic outcomes such as hypertension, type 2 diabetes (T2D), and ASCVD.

METHODS

We analyzed data from 9,591 adults from the National Survey of Health and Nutrition (ENSANUT) 2018 with fasting blood samples and complete medical history questionnaires. We built multivariate models to evaluate the association between chronic diseases and blood remnant concentration. To compare our 2018-sub-sample against a population reference, we used the NHANES (2005-2014) publicly available datasets by ethnicity.

RESULTS

Remnants were independently associated with cardiovascular risk, diabetes, hypertension, obesity, and metabolic syndrome. For all outcomes, the blood remnant concentration was a stronger predictor than LDL. At all deciles, the blood remnant concentration was higher in ENSANUT-2018.

CONCLUSIONS

A remnant blood concentration above 38 mg/dL was highly prevalent among Mexicans. Remnants were significantly associated with a higher risk of diabetes, hypertension, obesity, and cardiovascular risk. This association occurred independently of other lipid markers.

Remnant cholesterol and low-grade inflammation jointly in atherosclerotic cardiovascular disease: implications for clinical trials

PURPOSE OF REVIEW

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death despite the development of effective treatments. Recently, elevated remnant cholesterol and low-grade inflammation have emerged as factors explaining part of the residual ASCVD risk. Interestingly, the coexistence of both high remnant cholesterol and low-grade inflammation can further increase the risk of ASCVD. The aim of this review is to describe the role of elevated remnant cholesterol and low-grade inflammation, separately and combined, in ASCVD.

RECENT FINDINGS

Results from recently published studies, including observational and genetic Mendelian randomization studies, support a causal relationship between elevated remnant cholesterol and low-grade inflammation on risk of ASCVD in both primary and secondary prevention settings. In addition, current evidence from observational studies suggests that the coexistence of elevated remnant cholesterol and low-grade inflammation further increases the risk of ASCVD.

SUMMARY

Recent observational studies suggest that high remnant cholesterol combined with low-grade inflammation may confer a particular high risk for ASCVD. Attention on the dual threat from high remnant cholesterol and low-grade inflammation is necessary, and further research in this field is warranted. The effect of remnant cholesterol-lowering drugs and anti-inflammatory drugs on ASCVD risk alone and combined remains to be elucidated.

VIDEO ABSTRACT

http://links.lww.com/COCN/A20.

The chylomicron saga: time to focus on postprandial metabolism

Since statins have had such tremendous therapeutic success over the last three decades, the field of atherosclerosis has become somewhat LDL-centric, dismissing the relevance of triglycerides (TG), particularly chylomicrons, in atherogenesis. Nonetheless, 50% of patients who take statins are at risk of developing atherosclerotic cardiovascular disease (ASCVD) and are unable to achieve their goal LDL-C levels. This residual risk is mediated, in part by triglyceride rich lipoproteins (TRL) and their remnants. Following his seminal investigation on the subject, Zilversmit proposed that atherosclerosis is a postprandial event in 1979 (1-4). In essence, the concept suggests that remnant cholesterol-rich chylomicron (CM) and very-low density lipoprotein (VLDL) particles play a role in atherogenesis. Given the foregoing, this narrative review addresses the most recent improvements in our understanding of postprandial dyslipidemia. The primary metabolic pathways of chylomicrons are discussed, emphasizing the critical physiological role of lipoprotein lipase and apoCIII, the importance of these particles' fluxes in the postprandial period, their catabolic rate, the complexities of testing postprandial metabolism, and the role of angiopoietin-like proteins in the partition of CM during the fed cycle. The narrative is rounded out by the dysregulation of postprandial lipid metabolism in insulin resistance states and consequent CVD risk, the clinical evaluation of postprandial dyslipidemia, current research limits, and potential future study directions.

Unlocking the mysteries of VLDL: exploring its production, intracellular trafficking, and metabolism as therapeutic targets

Reducing circulating lipid levels is the centerpiece of strategies for preventing and treating atherosclerotic cardiovascular disease (ASCVD). Despite many available lipid-lowering medications, a substantial residual cardiovascular risk remains. Current clinical guidelines focus on plasma levels of low-density lipoprotein (LDL). Recent attention has been given to very low-density lipoprotein (VLDL), the precursor to LDL, and its role in the development of coronary atherosclerosis. Preclinical investigations have revealed that interventions targeting VLDL production or promoting VLDL metabolism, independent of the LDL receptor, can potentially decrease cholesterol levels and provide therapeutic benefits. Currently, methods, such as mipomersen, lomitapide, and ANGPTL3 inhibitors, are used to reduce plasma cholesterol and triglyceride levels by regulating the lipidation, secretion, and metabolism of VLDL. Targeting VLDL represents an avenue for new lipid-lowering strategies. Interventions aimed at reducing VLDL production or enhancing VLDL metabolism, independent of the LDL receptor, hold promise for lowering cholesterol levels and providing therapeutic benefits beyond LDL in the management of ASCVD.

Do Triglyceride-Rich Lipoproteins Equal Low-Density Lipoproteins in Risk of ASCVD?

PURPOSE OF REVIEW

Recent large clinical trials have failed to show that triglyceride-rich lipoprotein-lowering therapies decrease the risk of atherosclerotic cardiovascular disease (ASCVD). In this review, we reconcile these findings with evidence showing that elevated levels of triglyceride-rich lipoproteins and the cholesterol they contain, remnant cholesterol, cause ASCVD alongside low-density lipoprotein (LDL) cholesterol.

RECENT FINDINGS

Results from observational epidemiology, genetic epidemiology, and randomized controlled trials indicate that lowering of remnant cholesterol and LDL cholesterol decrease ASCVD risk by a similar magnitude per 1 mmol/L (39 mg/dL) lower non-high-density lipoprotein cholesterol (remnant cholesterol+LDL cholesterol). Indeed, recent guidelines for ASCVD prevention recommend the use of non-high-density lipoprotein cholesterol instead of LDL cholesterol. Current consensus is moving towards recognizing remnant cholesterol and LDL cholesterols as equals per 1 mmol/L (39 mg/dL) higher levels in the risk assessment of ASCVD; hence, triglyceride-rich lipoprotein-lowering therapies should also lower levels of non-HDL cholesterol to reduce ASCVD risk.