Triglycerides and remnant particles as risk factors for coronary artery disease

A realistic approach to evaluating the effect of baseline lipid profile in postcoronary artery bypass grafting surgery

BACKGROUND

There are still many uncertainties in the association between lipid profile and postcoronary artery bypass grafting (CABG) outcomes. Although simplifying the association to linear equations makes it understandable but cannot explain many findings.

HYPOTHESIS

There is a nonlinear associatin between lipid profile indices and adverse outcomes after CABG.

METHODS

A total of 17 555 patients who underwent isolated CABG between 2005 and 2016 were evaluated. During the median follow-up of 75.24 months, the Restricted Cubic Splines (RCS) estimated from the Cox regression model adjusted for all possible confounders was applied to show a nonlinear relationship of lipid profile contents with the "ln hazard ratio" of mortality and major cerebro-cardiac events (MACCE).

RESULTS

The relationship between LDL-C and HDL-C with all-cause mortality was nonlinear (nonlinear p were .004 and <.001, respectively). The relationship between remnant cholesterol and all-cause mortality was linear (linearity p = .023). Among men, those in the highest LDL-C level (Q4, LDL-C > 114) and those in the lowest HDL-C level (Q1, HDL-C < 30) showed a significantly higher risk of all-cause mortality compared to other groups (compared with Q3, LDL-C Q4, HR = 1.16, 95% confidence interval [CI]:1.02-1.26, p = .014; HDL-C Q1, HR = 1.14, 95% CI: 1.01-1.31, p = .041). Female patients in the lowest HDL-C level (Q1, HDL-C < 30) showed a significantly higher (compared with Q3, HR = 1.14, 95% CI:1.01-1.31, p = .028) and those in the highest HDL-C level (Q4, HDL-C > 43) showed a significantly lower (compared with Q3, HR = 0.74, 95% CI:0.58-0.98, p = .019) risk of all-cause mortality.

CONCLUSION

Determining a universal cut off for components of lipid profile may be misleading and should better be revised. Extreme values (very low or very high) for HDL-C and LDL-C have different effects on cardiovascular outcomes.

Comparison of calculated remnant lipoprotein cholesterol levels with levels directly measured by nuclear magnetic resonance

BACKGROUND

Remnant cholesterol (RC) can partly explain the residual risk in atherosclerotic cardiovascular disease (ASCVD). A consensus method of measuring RC levels has not been established yet. In clinical practice, RC levels are usually calculated from the standard lipid profile, which are not true RC. Nuclear magnetic resonance (NMR) can measure RC levels directly. This study aimed to characterize RC at fasting and non-fasting states in more details and establish the performance of calculated RC and NMR-measured RC.

METHODS

Blood samples at fasting state and at 2 h and 4 h postprandial states were collected in 98 subjects. Lipid parameters including total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), subfractions 3, 4, and 5 of very low-density lipoprotein cholesterol (VLDL3-C, VLDL4-C, and VLDL5-C, respectively), and intermediate-density lipoprotein cholesterol (IDL-C) were measured by enzymatic method and NMR. RC levels calculated from the standard lipid profile or measured by NMR were referred here as RCe or RCn.

RESULTS

The RCe and RCn levels were different, but both of them increased after a meal (P < 0.05), especially at 4 h postprandial state. Low correlations were found between RCe and RCn in the 1st, 2nd, and 3rd quartiles of TG, but RCn showed great correlation with RCe in the highest quartile regardless of the fasting or non-fasting state (R = 0.611, 0.536, and 0.535 for 0 h, 2 h, and 4 h, respectively). However, across the 2nd and 3rd quartiles, RCe levels were nearly close to RCn levels. RCe levels tended to overestimate RCn levels in the 1st quartile of TGe levels with median differences of 0.23(- 0.13, 0.63) and underestimate RCn levels with median differences of - 0.23(- 0.33, 0.07) in the highest quartile of TGe levels.

CONCLUSIONS

RC calculated from the standard lipid profile as TC minus LDL-C minus HDL-C is different from the NMR-measured RC. According to different TG levels, RC could overestimate or underestimate the actual RC level. Developing a consensus clinical method to measure RC levels is necessary, so that results from different studies and platforms can be more directly compared.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR1900020873. Registered in 21 January 2019 - Retrospectively registered.

Could remnant-like particle cholesterol become a risk factor in diabetic menopausal women with coronary artery disease? A cross-sectional study of single academic center in China

BACKGROUND AND AIMS

It has been confirmed that remnant-like particle cholesterol (RLP-C) mediates the progression of coronary artery disease (CAD). Currently there is limited information on RLP-C in menopausal women. With the special status of diabetes mellitus (DM) combined with the special body changes of the menopausal women, the RLP-C is particularly important when studying the changes that occurred in response to CAD and its associated risk factors. This study discussed whether RLP-C could be an independent risk factor for menopausal women with CAD and DM.

METHODS

The cohort consisted of 4753 menopausal women who had undergone coronary angiography. Subjects were separated into CAD and non-CAD groups, and univariate and multivariate logistic regression analysis of CAD risk factors were performed. All patients with a history of DM were divided into DM subgroups. Then, the univariate and multivariate logistic regression analysis of the risk factors of CAD and the comparison among age groups in the DM subgroup were performed. After age stratification of the DM group, the Kruskal-Wallis test was used to analyze the differences of various lipid indexes among age groups.

RESULTS

The multivariate logistic regression showed that RLP-C was an independent risk factor for CAD in menopausal women (OR 1.232, 95%CI 1.070-1.419). In the DM subgroup, it was also found that RLP-C was an independent risk factor for CAD (OR 1.366, 95%CI 1.043-1.791). Kruskal-Wallis test analysis found that RLP-C had no significant difference among three groups (P > 0.05).

CONCLUSIONS

RLP-C was proved to be an independent risk factor for menopausal women with CAD and DM.

Beneficial Effects of Adiponectin on Glucose and Lipid Metabolism and Atherosclerotic Progression: Mechanisms and Perspectives

Circulating adiponectin concentrations are reduced in obese individuals, and this reduction has been proposed to have a crucial role in the pathogenesis of atherosclerosis and cardiovascular diseases associated with obesity and the metabolic syndrome. We focus on the effects of adiponectin on glucose and lipid metabolism and on the molecular anti-atherosclerotic properties of adiponectin and also discuss the factors that increase the circulating levels of adiponectin. Adiponectin reduces inflammatory cytokines and oxidative stress, which leads to an improvement of insulin resistance. Adiponectin-induced improvement of insulin resistance and adiponectin itself reduce hepatic glucose production and increase the utilization of glucose and fatty acids by skeletal muscles, lowering blood glucose levels. Adiponectin has also β cell protective effects and may prevent the development of diabetes. Adiponectin concentration has been found to be correlated with lipoprotein metabolism; especially, it is associated with the metabolism of high-density lipoprotein (HDL) and triglyceride (TG). Adiponectin appears to increase HDL and decrease TG. Adiponectin increases ATP-binding cassette transporter A1 and lipoprotein lipase (LPL) and decreases hepatic lipase, which may elevate HDL. Increased LPL mass/activity and very low density lipoprotein (VLDL) receptor and reduced apo-CIII may increase VLDL catabolism and result in the reduction of serum TG. Further, adiponectin has various molecular anti-atherosclerotic properties, such as reduction of scavenger receptors in macrophages and increase of cholesterol efflux. These findings suggest that high levels of circulating adiponectin can protect against atherosclerosis. Weight loss, exercise, nutritional factors, anti-diabetic drugs, lipid-lowering drugs, and anti-hypertensive drugs have been associated with an increase of serum adiponectin level.

Safety, Tolerability, and Pharmacokinetics of Single and Multiple Oral Doses of an Omega-3-Carboxylic Acid Formulation in Healthy Male Japanese Subjects: A Phase 1 Single-Blind, Randomized, Placebo-Controlled Trial

OM3-CA (omega-3-carboxylic acids) is a complex mixture of omega-3 carboxylic acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which is approved in the United States for the treatment of hypertriglyceridemia. As part of its clinical development in Japan, we performed a phase 1 study to investigate the safety, tolerability, and pharmacokinetics after single and multiple doses of OM3-CA in healthy male Japanese subjects. Eighteen Japanese subjects were allocated to receive 2 or 4 g/day OM3-CA, or placebo (n = 6 per group). In addition, 6 white subjects received 4 g/day OM3-CA. The primary objective was to determine the safety and tolerability of OM3-CA. Plasma concentrations of EPA and DHA were adjusted for baseline values for pharmacokinetic analysis. Overall, OM3-CA was well tolerated in healthy Japanese subjects. Two Japanese subjects in each group and 5 white subjects experienced adverse events (AEs). Alanine aminotransferase increase was the most common AE in Japanese subjects, also seen with placebo, and diarrhea was the most common AE in white subjects. The maximum plasma concentrations of EPA and DHA were observed 5-6 hours postdose. The pharmacokinetic profiles of EPA and DHA after administration of OM3-CA were comparable between Japanese and white subjects.

Effect of Pitavastatin Treatment on ApoB-48 and Lp-PLA₂ in Patients with Metabolic Syndrome: Substudy of PROspective Comparative Clinical Study Evaluating the Efficacy and Safety of PITavastatin in Patients with Metabolic Syndrome

BACKGROUND

Apolipoprotein (Apo) B-48 is an intestinally derived lipoprotein that is expected to be a marker for cardiovascular disease (CVD). Lipoprotein-associated phospholipase A₂ (Lp-PLA₂) is a vascular-specific inflammatory marker and important risk predictor of CVD. The aim of this study was to explore the effect of pitavastatin treatment and life style modification (LSM) on ApoB-48 and Lp-PLA₂ levels in metabolic syndrome (MS) patients at relatively low risk for CVD, as a sub-analysis of a previous multi-center prospective study.

METHODS

We enrolled 75 patients with MS from the PROPIT study and randomized them into two treatment groups: 2 mg pitavastatin daily+intensive LSM or intensive LSM only. We measured the change of lipid profiles, ApoB-48 and Lp-PLA₂ for 48 weeks.

RESULTS

Total cholesterol, low density lipoprotein cholesterol, non-high density lipoprotein cholesterol, and ApoB-100/A1 ratio were significantly improved in the pitavastatin+LSM group compared to the LSM only group (P≤0.001). Pitavastatin+LSM did not change the level of ApoB-48 in subjects overall, but the level of ApoB-48 was significantly lower in the higher mean baseline value group of ApoB-48. The change in Lp-PLA₂ was not significant after intervention in either group after treatment with pitavastatin for 1 year.

CONCLUSION

Pitavastatin treatment and LSM significantly improved lipid profiles, ApoB-100/A1 ratio, and reduced ApoB-48 levels in the higher mean baseline value group of ApoB-48, but did not significantly alter the Lp-PLA₂ levels.

Apolipoprotein A-V deficiency enhances chylomicron production in lymph fistula mice

Apolipoprotein A-V (apoA-V), a liver-synthesized apolipoprotein discovered in 2001, strongly modulates fasting plasma triglycerides (TG). Little is reported on the effect of apoA-V on postprandial plasma TG, an independent predictor for atherosclerosis. Overexpressing apoA-V in mice suppresses postprandial TG, but mechanisms focus on increased lipolysis or clearance of remnant particles. Unknown is whether apoA-V suppresses the absorption of dietary lipids by the gut. This study examines how apoA-V deficiency affects the steady-state absorption and lymphatic transport of dietary lipids in chow-fed mice. Using apoA-V knockout (KO, n = 8) and wild-type (WT, n = 8) lymph fistula mice, we analyzed the uptake and lymphatic transport of lipids during a continuous infusion of an emulsion containing [(3)H]triolein and [(14)C]cholesterol. ApoA-V KO mice showed a twofold increase in (3)H (P < 0.001) and a threefold increase in (14)C (P < 0.001) transport into the lymph compared with WT. The increased lymphatic transport was accompanied by a twofold reduction (P < 0.05) in mucosal (3)H, suggesting that apoA-V KO mice more rapidly secreted [(3)H]TG out of the mucosa into the lymph. ApoA-V KO mice also produced chylomicrons more rapidly than WT (P < 0.05), as measured by the transit time of [(14)C]oleic acid from the intestinal lumen to lymph. Interestingly, apoA-V KO mice produced a steadily increasing number of chylomicron particles over time, as measured by lymphatic apoB output. The data suggest that apoA-V suppresses the production of chylomicrons, playing a previously unknown role in lipid metabolism that may contribute to the postprandial hypertriglyceridemia associated with apoA-V deficiency.

Fasting serum concentration of apolipoprotein B48 represents residual risks in patients with new-onset and chronic coronary artery disease

BACKGROUND

To identify new therapeutic targets for coronary artery disease (CAD), we investigated whether fasting serum concentration of apolipoprotein (apo) B48 could be a marker for CAD.

METHODS

Patients with CAD were divided into those with new-onset CAD [i.e., those receiving percutaneous coronary intervention (PCI) for the first time] and those with chronic CAD (i.e., those receiving follow-up coronary angiography). Fasting serum biochemical analyses were performed on admission and 6 months after the PCI.

RESULTS

On admission, serum LDL-C concentrations in patients with chronic CAD (n=138), presumably receiving statin treatment, were lower than in patients with new-onset CAD (n=50, p<0.02) or without CAD (n=71, p<0.001). Nevertheless, apoB48 was higher in CAD patients than in those without CAD (p<0.001). After adjusting for classic cardiovascular risk factors, multivariate logistic regression analyses showed apoB48 to be an independent predictor of coronary risk in new-onset or chronic CAD, irrespective of the LDL-C levels. Moreover, apoB48 was markedly increased during the follow-up period in CAD patients having new lesion progression after the prior PCI.

CONCLUSION

Fasting serum apoB48 concentration could be a marker of new onset as well as chronic CAD, and predict new lesion progression in secondary prevention.

Lipid-regulating effect of traditional chinese medicine: mechanisms of actions

Traditional Chinese medicine (TCM) has been increasingly used for the treatment of dyslipidemia and cardiovascular disease. Recently, much progress has been made in studies on the mechanisms of action of the lipid-regulating effect of TCM in animal experiments. Current researches showed that the lipid-regulating effect of TCM may be related to the following actions: (1) inhibiting intestinal absorption of lipids; (2) reducing the biosynthesis of endogenous lipids; (3) increasing the catabolism of lipid, sterol substances in live system; (4) increasing the secretion of sterol substances in live system; (5) regulating transcription factors related to lipid metabolism. This paper provides an overview of the recent advances and discusses their implications in future development of lipid-lowering drugs from TCM.

Effects of farnesoid X receptor on the expression of the fatty acid synthetase and hepatic lipase

The farnesoid X receptor (FXR) is a nuclear receptor that regulates gene expression in response to bile acids (BAs). FXR plays an important role in the homeostasis of bile acid, cholesterol, lipoprotein and triglyceride. In this report, we identified fatty acid synthase (FAS) and hepatic lipase (HL) genes as novel target genes of FXR. Human hepatoma HepG2 cells were treated with chenodeoxycholic acid, the natural FXR ligand, and the messenger RNA and protein levels of FAS and HL were determined by RT-PCR and Western blot analysis, respectively. Chenodeoxycholic acid (CDCA) down-regulated the expression of FAS and HL genes in a dose and time-dependent manner in human hepatoma HepG2 cells. In addition, treatment of mice with CDCA significantly decreased the expression of FAS and HL in mouse liver and the activity of HL. These results demonstrated that FAS and HL might be FXR-regulated genes in liver cells. In view of the role of FAS and HL in lipogenesis and plasma lipoprotein metabolism, our results further support the central role of FXR in the homeostasis of fatty acid and lipid.

Lectin-like oxidized LDL receptor-1 (LOX-1) acts as a receptor for remnant-like lipoprotein particles (RLPs) and mediates RLP-induced migration of vascular smooth muscle cells

OBJECTIVE

Remnant-like lipoprotein particles (RLPs) have been implicated in atherogenesis especially by diabetic dyslipidemia; however, their receptor(s) and effects on vascular smooth muscle cells (VSMCs) remain unclear. In this study, we examined if lectin-like oxidized LDL receptor-1 (LOX-1) acts as a receptor for RLPs and its biological effects in VSMCs.

METHODS AND RESULTS

RLPs were isolated from human plasma by immunoaffinity gel containing anti-apolipoprotein A-I and anti-apolipoprotein B-100 monoclonal antibodies. DiI-labeled RLPs were taken up by CHO-K1 cells stably expressing LOX-1 but not by wild-type CHO-K1 cells. RLPs induced LOX-1 expression and cell migration in bovine VSMCs (BVSMCs), which were significantly suppressed by transfection with LOX-1 specific siRNAs. Inhibitors of metalloproteinases, epidermal growth factor (EGF) receptor tyrosine kinase, heparin-binding EGF-like growth factor (HB-EGF), p38 mitogen-activated protein kinase (p38 MAPK), MAPK kinase (MEK1) and phosphoinositide 3-kinase (PI3K) significantly blocked RLP-induced LOX-1 expression and cell migration of BVSMCs.

CONCLUSIONS

The present study provides direct evidence that LOX-1 is a novel receptor for RLPs in VSMCs. LOX-1-mediated uptake of RLPs may thus play important roles in atherogenesis by inducing LOX-1 expression and VSMC migration especially in the settings of postprandial hyperlipidemia, diabetes and metabolic syndrome.

Increased remnant lipoprotein in patients with coronary artery disease--evaluation utilizing a newly developed remnant assay, remnant lipoproteins cholesterol homogenous assay (RemL-C)

AIM

Remnant lipoprotein is an emerging risk factor for coronary artery disease (CAD); however, the development of a specific remnant lipoprotein assay has struggled due to its heterogeneous nature. This study aimed to evaluate the clinical importance of a newly developed assay for remnant lipoprotein, RemL-C, in patients with CAD.

METHODS

This assay utilizes surfactant and phospholipase-D to selectively degrade and solubilize remnant lipoprotein. One hundred and sixty consecutive CAD patients who underwent coronary catheterization were recruited.

RESULTS

Remnant liporotein, RemL-C, was significantly higher in CAD patients (p< 0.001). Additionally, TG, hs-CRP, ICAM-1, VCAM-1, and homocysteine were significantly higher, but HDL-C and adiponectin were lower with LDL-C unchanged. Since RemL-C levels correlated with plasma TG levels, two subgroups, normotriglycedemic and normolipidemic CAD groups, were extracted. In both groups, RemL-C was still significantly higher than controls. HDL-C, but not RemL-C, was associated with the severity of CAD. RemL-C significantly correlated with TG-rich lipoproteins, in particular VLDL and IDL, when limited to normolipidemic CAD patients.

CONCLUSION

Remnant lipoprotein, measured by RemL-C, was increased in CAD patients independent of TG levels, indicating impaired remnant lipoprotein metabolism in these patients. CAD severity was associated with HDL-C, but not with remnant lipoprotein, indicating differential roles of lipoproteins in the development of coronary atherosclerosis. This study therefore provides clinical significance to assess coronary risk by measuring RemL-C, particularly among patients with normal TG levels.

Differentiating prescription omega-3-acid ethyl esters (P-OM3) from dietary-supplement omega-3 fatty acids

BACKGROUND

A reliable means of treating hyper-triglyceridemia is the use of large doses of the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Modest levels of EPA and DHA may be obtained from food, particularly fatty fish.

OBJECTIVES

This article is intended to review clinically relevant differences between dietary-supplement omega-3 fatty acids and prescription omega-3-acid ethyl esters (P-OM3).

METHODS

PubMed and the Food and Drug Administration (FDA) Website were searched for articles published between 1995 and 2007 that contained the terms fish oil, fatty acids, n-3 fatty acids, omega fatty acids, docosahexaenoic acid, or eicosapentaenoic acid. Articles discussing sources, recommended intake, and differences among various formulations of omega-3 fatty acids were selected for review. A limitation to this review is the lack of head-to-head clinical trials using P-OM3 and dietary-supplement omega-3 fatty acids.

RESULTS

Many types of nonprescription dietary supplements of omega-3 fatty acids are available; however, the efficacy, quality, and safety of these products are open to question because they are not regulated by the same standards as pharmaceutical agents. P-OM3 is the only omega-3 fatty acid product (Omacor capsules) approved by the US FDA available in the United States as an adjunct to diet to reduce very high (> or = 500 mg/dL) triglyceride levels in adult patients.

CONCLUSIONS

P-OM3 can be used with confidence by practitioners who want to provide therapeutic doses of omega-3 fatty acids in a preparation that has been documented to be both safe and effective.

Cholesterol Profile Measurement by Vertical Auto Profile Method

Vertical auto profile (VAP) method is a direct single test for measuring comprehensive lipoprotein cholesterol profile. It is based on a well-established method of ultracentrifugation that uses vertical rotor and single density gradient spin. VAP provides cholesterol concentrations of total lipoprotein, high-density lipoprotein (HDL), low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL), lipoprotein(a) (Lp(a)), intermediate-density lipoprotein (IDL), HDL subclasses (HDL2 and HDL3), LDL subclasses (LDL1, LDL2, LDL3, and LDL4), VLDL subclasses (VLDL1, VLDL2, and VLDL3), and LDL maximum time, which is directly proportional to LDL size. Because VAP measures additional lipoprotein classes, such as Lp(a), IDL, and subclasses of HDL, LDL, and VLDL, it can identify patients at high risk for coronary heart disease who cannot be identified using the standard lipid panel. In addition, the VAP method is compliant with the National Cholesterol Education Program's Adult Treatment Panel III guidelines.