Triglyceride-Rich Lipoproteins and Remnant Cholesterol in Cardiovascular Disease

Predictive utility of remnant cholesterol in atherosclerotic cardiovascular disease

PURPOSE OF REVIEW

Remnant cholesterol (RC) is the cholesterol carried in lipoproteins derived from the catabolism of chylomicrons and very low-density lipoproteins. Evidence supporting the causal relationship of RC with atherosclerotic cardiovascular disease (ASVD) is accumulating rapidly. The number of impactful contributions to this field are increasing and provide a pathophysiological insight into the current residual cardiovascular risk beyond low-density cholesterol (LDL)-cholesterol (LDL-C). They also raise the question of whether RC should be used in prediction models and become the target of new therapeutic interventions. The intent of this review is to highlight the recent advances on the role of RC in atherogenesis and the validation of RC as a predictor of ASVD.

RECENT FINDINGS

Numerous prospective and retrospective cohorts helped validate a significant causal relationship of RC with various forms of ASVD, independent of LDL-C. A recent large Mendelian randomization study reinforced the existence of this relationship and showed that the risk of atherosclerotic events was driven nearly entirely by a direct effect of RC.

SUMMARY

Both available and accumulating evidence suggest that a lifelong reduction in RC could translate into a substantial reduction in ASVD risk. The data support a revision of current guidelines to incorporate RC as an independent risk factor for ASVD. We propose that early screening of RC should be implemented and that RC lowering should become the target of future drug developments.

Remnant cholesterol as a new lipid-lowering target to reduce cardiovascular events

PURPOSE OF REVIEW

Remnant cholesterol has become increasingly recognized as a direct contributor to the development of atherosclerosis and as an additional marker of cardiovascular risk. This review aims to summarize the pathophysiological mechanisms, and the current evidence base from epidemiological investigations and genetic studies that support a causal link between remnant cholesterol and atherosclerotic cardiovascular disease. Current and novel therapeutic approaches to target remnant cholesterol are discussed.

RECENT FINDINGS

A recent Mendelian randomization study of over 12 000 000 single-nucleotide polymorphisms associated with high levels of remnant cholesterol, demonstrated a genetic association between remnant cholesterol and adverse cardiovascular events among 958 434 participants.

SUMMARY

In this light, the emerging role of remnant cholesterol as an independent lipid risk marker warrants a reevaluation of lipid management guidelines and underscores the potential for novel therapeutic targets in cardiovascular disease prevention.

New approaches to triglyceride reduction: Is there any hope left?

Triglycerides play a crucial role in the efficient storage of energy in the body. Mild and moderate hypertriglyceridemia (HTG) is a heterogeneous disorder with significant association with atherosclerotic cardiovascular disease (ASCVD), including myocardial infarction, ischemic stroke, and peripheral artery disease and represents an important component of the residual ASCVD risk in statin treated patients despite optimal low-density lipoprotein cholesterol reduction. Individuals with severe HTG (>1,000 mg/dL) rarely develop atherosclerosis but have an incremental incidence of acute pancreatitis with significant morbidity and mortality. HTG can occur from a combination of genetic (both mono and polygenic) and environmental factors including poor diet, low physical activity, obesity, medications, and diseases like insulin resistance and other endocrine pathologies. HTG represents a potential target for ASCVD risk and pancreatitis risk reduction, however data on ASCVD reduction by treating HTG is still lacking and HTG-associated acute pancreatitis occurs too rarely to effectively demonstrate treatment benefit. In this review, we address the key aspects of HTG pathophysiology and examine the mechanisms and background of current and emerging therapies in the management of HTG.

Remnant cholesterol is an independent risk factor for the incidence of chronic kidney disease in newly-diagnosed type 2 diabetes: A nationwide population-based study

AIMS

To evaluate the impact of remnant cholesterol (remnant-C) on chronic kidney disease (CKD) incidence in newly-diagnosed type 2 diabetes.

METHODS

This retrospective cohort study used Korean National Health Insurance Service data on 212,836 patients with newly-diagnosed type 2 diabetes between 2009 and 2014. We conducted cox regression analysis to calculate hazard ratios (HRs) with 95% confidence intervals (CIs) for developing CKD according to remnant-C tertile.

RESULTS

During a median follow-up duration of 5.23 years, 6,850 CKD cases developed. In the fully adjusted model, HRs and 95 % CIs for incident CKD increased in the highest tertile of baseline remnant-C compared to the lowest (HR [95 % CI]; 1.234 [1.159-1.314]). This association was more prominent in patients with hypertension or low-income status (P for interaction < 0.05). Increased HRs in the highest tertile of remnant-C was sustained in type 2 diabetes patients within target range of conventional lipid profile such as low-density lipoprotein cholesterol (LDL-C) < 100 mg/dL and < 70 mg/dL (1.165 [1.041-1.304] and 1.308 [1.063-1.609]), high-density lipoprotein cholesterol (HDL-C) (1.243 [1.155-1.338]) and triglyceride (1.168 [1.076-1.268]), respectively.

CONCLUSIONS

In newly-diagnosed type 2 diabetes patients, higher remnant-C is independently associated with CKD incidence, even when conventional lipid values are well-controlled.

Revisiting an old relationship: the causal associations of the ApoB/ApoA1 ratio with cardiometabolic diseases and relative risk factors-a mendelian randomization analysis

BACKGROUND

It has been confirmed that the ApoB/ApoA1 ratio is closely associated with the incidence of cardiometabolic diseases (CMD). However, due to uncontrolled confounding factors in observational studies, the causal relationship of this association remains unclear.

METHODS

In this study, we extracted the ApoB/ApoA1 ratio and data on CMD and its associated risk factors from the largest European Genome-Wide Association Study. The purpose was to conduct Mendelian Randomization (MR) analysis. The causal relationship between the ApoB/ApoA1 ratio and CMD was evaluated using both univariable and multivariable MR analyses. Furthermore, bidirectional MR analysis was performed to estimate the causal relationship between the ApoB/ApoA1 ratio and risk factors for CMD. The final verification confirmed whether the ApoB/ApoA1 ratio exhibits a mediating effect in CMD and related risk factors.

RESULTS

In terms of CMD, a noteworthy correlation was observed between the increase in the ApoB/ApoA1 ratio and various CMD, including ischemic heart disease, major adverse cardiovascular events, aortic aneurysm, cerebral ischemic disease and so on (all PFDR<0.05). Meanwhile, the ApoB/ApoA1 ratio was significantly associated with CMD risk factors, such as hemoglobin A1c, fasting insulin levels, waist-to-hip ratio, sedentary behavior, and various others, demonstrating a notable causal relationship (all PFDR<0.05). Additionally, the ApoB/ApoA1 ratio played a mediating role in CMD and relative risk factors.

CONCLUSIONS

This MR study provides evidence supporting the significant causal relationship between the ApoB/ApoA1 ratio and CMD and its risk factors. Moreover, it demonstrates the mediating effect of the ApoB/ApoA1 ratio in CMD and its risk factors. These findings suggest that the ApoB/ApoA1 ratio may serve as a potential indicator for identifying the risk of developing CMD in participants.

Assessing the Efficacy of Omega-3 Fatty Acids + Statins vs. Statins Only on Cardiovascular Outcomes: A Systematic Review and Meta-Analysis of 40,991 Patients

BACKGROUND

Clinical guidelines recommend statin use in patients with a vast array of cardiovascular disturbances. However, there is insufficient evidence regarding the concomitant use of omega-3 fatty acids in addition to statins. This meta-analysis aims to uncover the complete effects of this combination therapy on cardiovascular outcomes, lipid biomarkers, inflammatory markers, and plaque markers.

METHODS

A detailed literature search was conducted using PubMed, Cochrane, and MEDLINE databases, and all the relevant studies found up to September 2023 were included. The primary outcomes assessed in this meta-analysis was 1) Composite of fatal and non-fatal myocardial infarction, 2) Composite of fatal and non-fatal stroke, 3) Coronary revascularization, 4) Death due to cardiovascular causes, 5) MACE (Major Adverse Cardiovascular Events), 6) Unstable angina, 7) Hospitalization due to unstable angina, 8) and lipid volume index. Secondary outcomes included lipid markers, hsCRP, EPA levels, and EPA/AA ratio.

RESULTS

14 RCTs were included, featuring a total of 40,991 patients. Patients receiving the omega-3 + statin regimen were associated with a statistically significant decrease in the incidence of MI, MACE, unstable angina, hospitalization due to unstable angina, Total cholesterol levels, triglycerides, hsCRP, and lipid volume index in comparison to their counterparts receiving placebo + statin (P < 0.05). In contrast, our analysis found no statistically significant difference in the incidence of fatal and non-fatal stroke, coronary revascularization, and cardiovascular mortality.

CONCLUSION

Our research reinforces that all patients, regardless of their cardiovascular health, may benefit from adding omega-3 fatty acids to their statin therapy.

Cumulative residual cholesterol predicts the risk of cardiovascular disease in the general population aged 45 years and older

BACKGROUND

Numerous studies have affirmed a robust correlation between residual cholesterol (RC) and the occurrence of cardiovascular disease (CVD). However, the current body of literature fails to adequately address the link between alterations in RC and the occurrence of CVD. Existing studies have focused mainly on individual RC values. Hence, the primary objective of this study is to elucidate the association between the cumulative RC (Cum-RC) and the morbidity of CVD.

METHODS

The changes in RC were categorized into a high-level fast-growth group (Class 1) and a low-level slow-growth group (Class 2) by K-means cluster analysis. To investigate the relationship between combined exposure to multiple lipids and CVD risk, a weighted quantile sum (WQS) regression analysis was employed. This analysis involved the calculation of weights for total cholesterol (TC), low-density lipoprotein (LDL), and high-density lipoprotein (HDL), which were used to effectively elucidate the RC.

RESULTS

Among the cohort of 5,372 research participants, a considerable proportion of 45.94% consisted of males, with a median age of 58. In the three years of follow-up, 669 participants (12.45%) had CVD. Logistic regression analysis revealed that Class 2 individuals had a significantly reduced risk of developing CVD compared to Class 1. The probability of having CVD increased by 13% for every 1-unit increase in the Cum-RC according to the analysis of continuous variables. The restricted cubic spline (RCS) analysis showed that Cum-RC and CVD risk were linearly related (P for nonlinearity = 0.679). The WQS regression results showed a nonsignificant trend toward an association between the WQS index and CVD incidence but an overall positive trend, with the greatest contribution from TC (weight = 0.652), followed by LDL (weight = 0.348).

CONCLUSION

Cum-RC was positively and strongly related to CVD risk, suggesting that in addition to focusing on traditional lipid markers, early intervention in patients with increased RC may further reduce the incidence of CVD.

Causes of Sex Differences in Serum Cholesterol and Triglyceride Levels in Meishan Pigs

To clarify the causes of sex differences (male < female) in the serum total cholesterol (TCHO) and triglyceride (TG) levels in Meishan pigs, we examined the sex differences in mRNA levels of key hepatic enzymes involved in the biosynthesis/metabolism of cholesterol and TG using real-time RT-PCR. There were no sex differences in mRNA levels of 3-hydroxy-3-methylglutaryl-CoA reductase and CYP51A1 for cholesterol biosynthesis, or of the rate-limiting enzyme CYP7A1 for bile acid synthesis from cholesterol. By contrast, sex differences (male < female) were observed in mRNA levels of glycerol-3-phosphate acyltransferase 1 (GPAT1), a rate-limiting enzyme for TG biosynthesis. However, the sex differences in mRNA levels of carnitine palmitoyltransferase 1A (CPT1A) and acyl-CoA dehydrogenase long chain (ACADL), key enzymes for the oxidation of the fatty acids that are structural components of TG, were the opposite (male > female). Castration of male pigs led to an increase in the mRNA level of GPAT1 and decreases in those of CPT1A and ACADL. Furthermore, testosterone propionate (TP)-treatment of castrated males and intact females restored and changed, respectively, these mRNA levels to those of intact males. Notably, castration and TP-treatment increased and decreased, respectively, serum and hepatic TG levels. These findings suggest that sex differences in the serum and hepatic TG levels in Meishan pigs are closely correlated with differences in testosterone-associated mRNA expression levels of the key enzymes (GPAT1, CPT1A, and ACADL) involved in the TG biosynthesis process, although no causes of sex differences in serum and hepatic TCHO levels could be found.