Distinct Differences in Lipoprotein Particle Number Evaluation between GP-HPLC and NMR: Analysis in Dyslipidemic Patients Administered a Selective PPARα Modulator, Pemafibrate

Sex differences in the associations of HDL particle concentration and cholesterol efflux capacity with incident coronary artery disease in type 1 diabetes: The RETRO HDLc cohort study

BACKGROUND

In type 1 diabetes, women lose their relative protection (compared to men) against coronary artery disease (CAD), while high-density lipoprotein cholesterol (HDL-C) is less strongly associated with lower CAD risk in women.

OBJECTIVE

We aimed to assess whether sex differences in the HDL particle concentration (HDL-P) and cholesterol efflux capacity (CEC) association with CAD may explain these findings.

METHODS

HDL-P (calibrated differential ion mobility analysis) and total and ATP binding cassette transporter A1 (ABCA1)-specific CEC were quantified among 279 men and 271 women with type 1 diabetes (baseline mean age 27·8 years; diabetes duration, 19·6 years). Clinical CAD was defined as CAD death, myocardial infarction and/or coronary revascularization.

RESULTS

Women had higher large HDL-P levels and marginally lower concentrations of small HDL-P and ABCA1-specific CEC than men. No sex differences were observed in extra-small HDL-P, medium HDL-P and total CEC. During a median follow-up of 26 years, 37·6 % of men and 35·8 % of women developed CAD (p = 0·72). In multivariable Cox models stratified by sex (pTotal HDL-P x sex interaction=0·01), HDL-P was negatively associated with CAD incidence in both sexes. However, associations were stronger in men, particularly for extra-small HDL-P (hazard ratio (HR)men=0·11, 95 % confidence interval (CI): 0·04-0·30; HRwomen=0·68, 95 % CI: 0·28-1·66; pinteraction=0·001). CEC did not independently predict CAD in either sex.

CONCLUSION

Despite few absolute differences in HDL-P concentrations by sex, the HDL-P - CAD association was weaker in women, particularly for extra-small HDL-P, suggesting that HDL-P may be less efficient in providing atheroprotection in women and perhaps explaining the lack of a sex difference in CAD in type 1 diabetes.

Relationship between the cholesterol and triglyceride content of lipoprotein subclasses and carotid intima-media thickness: A cross-sectional population-based study

BACKGROUND

The association between lipoprotein subclasses and carotid intima-media thickness (cIMT) progression has yet to be fully evaluated. We assessed which lipoprotein subclasses were associated with maximum cIMT levels in the general population.

METHODS

In this study, cholesterol and triglyceride content of 20 lipoprotein subclasses were analyzed using gel permeation high-performance liquid chromatography (GP-HPLC) in 864 Japanese women and men (mean age 57 y, free of chronic liver or kidney diseases and off lipid-lowering, hormone replacement, or adrenocorticosteroid medications). Univariate and multivariate regression analyses and univariate and partial correlation analyses were performed to examine the relationships between lipoprotein subclasses and maximum cIMT levels.

RESULTS

After adjusting for age, sex, systolic blood pressure, smoking, diabetes, and anti-hypertensive agents, elevated low-density lipoprotein (LDL)-2 and -3 cholesterol (particle diameter 25.5 nm and 23.0 nm, respectively; medium and small LDL) were associated with higher maximum cIMT levels in both women and men (all p for trend < 0.05). These associations were significant even after participants taking anti-diabetic or anti-hypertensive agents were excluded. No significant associations were found between any triglyceride subclasses and maximum cIMT levels.

CONCLUSIONS

Smaller LDL particle cholesterol values are the most atherogenic lipoprotein parameter.

Novel Selective PPARα Modulator Pemafibrate for Dyslipidemia, Nonalcoholic Fatty Liver Disease (NAFLD), and Atherosclerosis

Statins, the intestinal cholesterol transporter inhibitor (ezetimibe), and PCSK9 inhibitors can reduce serum LDL-C levels, leading to a significant reduction in cardiovascular events. However, these events cannot be fully prevented even when maintaining very low LDL-C levels. Hypertriglyceridemia and reduced HDL-C are known as residual risk factors for ASCVD. Hypertriglyceridemia and/or low HDL-C can be treated with fibrates, nicotinic acids, and n-3 polyunsaturated fatty acids. Fibrates were demonstrated to be PPARα agonists and can markedly lower serum TG levels, yet were reported to cause some adverse effects, including an increase in the liver enzyme and creatinine levels. Recent megatrials of fibrates have shown negative findings on the prevention of ASCVD, which were supposed to be due to their low selectivity and potency for binding to PPAR α. To overcome the off-target effects of fibrates, the concept of a selective PPARα modulator (SPPARMα) was proposed. Kowa Company, Ltd. (Tokyo, Japan), has developed pemafibrate (K-877). Compared with fenofibrate, pemafibrate showed more favorable effects on the reduction of TG and an increase in HDL-C. Fibrates worsened liver and kidney function test values, although pemafibrate showed a favorable effect on liver function test values and little effect on serum creatinine levels and eGFR. Minimal drug-drug interactions of pemafibrate with statins were observed. While most of the fibrates are mainly excreted from the kidney, pemafibrate is metabolized in the liver and excreted into the bile. It can be used safely even in patients with CKD, without a significant increase in blood concentration. In the megatrial of pemafibrate, PROMINENT, for dyslipidemic patients with type 2 diabetes, mild-to-moderate hypertriglyceridemia, and low HDL-C and LDL-C levels, the incidence of cardiovascular events did not decrease among those receiving pemafibrate compared to those receiving the placebo; however, the incidence of nonalcoholic fatty liver disease was lower. Pemafibrate may be superior to conventional fibrates and applicable to CKD patients. This current review summarizes the recent findings on pemafibrate.

Triglyceride Lowering with Pemafibrate to Reduce Cardiovascular Risk

BACKGROUND

High triglyceride levels are associated with increased cardiovascular risk, but whether reductions in these levels would lower the incidence of cardiovascular events is uncertain. Pemafibrate, a selective peroxisome proliferator-activated receptor α modulator, reduces triglyceride levels and improves other lipid levels.

METHODS

In a multinational, double-blind, randomized, controlled trial, we assigned patients with type 2 diabetes, mild-to-moderate hypertriglyceridemia (triglyceride level, 200 to 499 mg per deciliter), and high-density lipoprotein (HDL) cholesterol levels of 40 mg per deciliter or lower to receive pemafibrate (0.2-mg tablets twice daily) or matching placebo. Eligible patients were receiving guideline-directed lipid-lowering therapy or could not receive statin therapy without adverse effects and had low-density lipoprotein (LDL) cholesterol levels of 100 mg per deciliter or lower. The primary efficacy end point was a composite of nonfatal myocardial infarction, ischemic stroke, coronary revascularization, or death from cardiovascular causes.

RESULTS

Among 10,497 patients (66.9% with previous cardiovascular disease), the median baseline fasting triglyceride level was 271 mg per deciliter, HDL cholesterol level 33 mg per deciliter, and LDL cholesterol level 78 mg per deciliter. The median follow-up was 3.4 years. As compared with placebo, the effects of pemafibrate on lipid levels at 4 months were -26.2% for triglycerides, -25.8% for very-low-density lipoprotein (VLDL) cholesterol, -25.6% for remnant cholesterol (cholesterol transported in triglyceride-rich lipoproteins after lipolysis and lipoprotein remodeling), -27.6% for apolipoprotein C-III, and 4.8% for apolipoprotein B. A primary end-point event occurred in 572 patients in the pemafibrate group and in 560 of those in the placebo group (hazard ratio, 1.03; 95% confidence interval, 0.91 to 1.15), with no apparent effect modification in any prespecified subgroup. The overall incidence of serious adverse events did not differ significantly between the groups, but pemafibrate was associated with a higher incidence of adverse renal events and venous thromboembolism and a lower incidence of nonalcoholic fatty liver disease.

CONCLUSIONS

Among patients with type 2 diabetes, mild-to-moderate hypertriglyceridemia, and low HDL and LDL cholesterol levels, the incidence of cardiovascular events was not lower among those who received pemafibrate than among those who received placebo, although pemafibrate lowered triglyceride, VLDL cholesterol, remnant cholesterol, and apolipoprotein C-III levels. (Funded by the Kowa Research Institute; PROMINENT ClinicalTrials.gov number, NCT03071692.).

First-in-human autologous implantation of genetically modified adipocytes expressing LCAT for the treatment of familial LCAT deficiency

Background

Familial lecithin: cholesterol acyltransferase (LCAT) deficiency (FLD) is a severe inherited disease without effective treatment. Patients with FLD develop severe low HDL, corneal opacity, hemolytic anemia, and renal injury.

Objective

We developed genetically modified adipocytes (GMAC) secreting LCAT (LCAT-GMAC) for ex vivo gene therapy. GMACs were prepared from the patient’s adipocytes to express LCAT by retroviral gene transduction to secrete functional enzymes. This study aimed to evaluate the safety and efficacy of LCAT-GMAC implantation in an FLD patient.

Methods

Proliferative preadipocytes were obtained from a patient using a ceiling culture and retrovirally transduced with LCAT. After obtaining enough cells by expansion culture of the transduced cells, the resulting LCAT-GMACs were implanted into a patient with FLD. To evaluate the safety and efficacy, we analyzed the outcome of the autologous implantation for 24 weeks of observation and subsequent 240 weeks of the follow-up periods.

Results

This first-in-human autologous implantation of LCAT-GMACs was shown to be safe by evaluating adverse events. The LCAT-GMAC implantation increased serum LCAT activity by approximately 50% of the baseline and sustained over three years. Consistent with increased LCAT activity, intermediate-density lipoprotein (IDL) and free cholesterol levels of the small and very small HDL fractions decreased. We found the hemoglobin/haptoglobin complex in the hemolyzed pre-implantation sera of the patient. After one week of the implantation, the hemoglobin/haptoglobin complex almost disappeared. Immediately after the implantation, the patient's proteinuria decreased temporarily to mild levels and gradually increased to the baseline. At 48 weeks after implantation, the patient's proteinuria deteriorated with the development of mild hypertension. By the treatment with antihypertensives, the patient's blood pressure normalized. With the normalization of blood pressure, the proteinuria rapidly decreased to mild proteinuria levels.

Conclusions

LCAT-GMAC implantation in a patient with FLD is shown to be safe and appears to be effective, in part, for treating anemia and proteinuria in FLD.

The profile of HDL-C subfractions and their association with cardiovascular risk in the Hungarian general and Roma populations

High-density lipoprotein cholesterol (HDL-C) is not a homogenous lipid fraction, but it can be further divided into subfractions. It is well-known that the Roma population has a high prevalence of reduced HDL-C levels and cardiovascular diseases (CVDs). However, it is unknown how this reduction affects different HDL subfractions, and whether changes in their quantity/representation are associated with an increased cardiovascular risk among them. In the present study, the HDL subfraction profile of the Hungarian general (HG) and the Roma populations were compared, and the subfractions showing a significant difference between the two populations were identified. The association of HDL subfractions with CVD risk estimated by the Framingham risk score (FRS) and the Systematic COronary Risk Evaluation (SCORE) algorithms were also defined. The present study is the first to find a significant association between HDL subfractions and cardiovascular risk estimated by FRS and SCORE. Ten HDL subfractions were investigated on small but carefully selected samples comprising 100 control subjects (with normal lipid profile) and 277 case subjects (with reduced HDL-C levels) from HG and Roma populations of a complex health survey. The level of HDL-1 to 3 subfractions and HDL-L showed a significant inverse association with cardiovascular risk estimated by both SCORE and FRS algorithms, whereas HDL-4 to 6 and HDL-I only for FRS. A higher representation (in %) of HDL-1 to 3 has a significant risk-reducing effect, while HDL-8 to 10 has a risk-increasing effect estimated by FRS. Our results confirmed that reduced levels of HDL-6 and -7 expressed in mmol/L were significantly associated with Roma ethnicity.

Development of internal standard for lipoprotein subclass analysis using dual detection gel-permeation high-performance liquid chromatography system

The LipoSEARCH® System is an innovative lipoprotein class analysis method based on gel-permeation high-performance liquid chromatography (HPLC). This system uses a gel permeation column to separate the major lipoprotein subclasses (chylomicron, very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein) in serum according to particle size and splits them into two pathways to measure total cholesterol (TC; esterified + unesterified cholesterol) and triglyceride (TG) concentrations simultaneously to obtain chromatograms for each.

These chromatograms were analyzed based on the results of the calibration serum by fitting Gaussian curves to profile the 20 lipoprotein subclasses defined in detail. An important assumption of this HPLC system is its simultaneous detection of two pathways to guarantee the accuracy of each analysis. Therefore, in the present study, we investigated the development of an internal standard that can guarantee the simultaneous detection of this system by adding a pigment to the serum. We focused on quinone pigments with absorption at 550 nm, which is the wavelength used for the enzymatic assay of TC and TG concentrations in the system. As a result, we succeeded in producing overlapping pigment peaks that appeared after the analytical chromatograms in two pathways. It is also suggested that the pigment solution as an internal standard is stable in freezing storage and has little effect on the analysis. The developed internal standard is expected to contribute to the accuracy assurance of lipoprotein analysis by this dual-detection HPLC system.

Lipoprotein-subclass particle numbers in children with abdominal obesity

BACKGROUND

The lipoprotein particle number (PN) profile may be a better marker of cardiovascular risks than standard serum lipid measurements. The aim of this study was to analyze the lipoprotein PNs in Japanese children with abdominal obesity and to determine the subclass profile.

METHODS

The participants included 164 Japanese children (79 boys and 85 girls) aged 9-13 years. We obtained waist-to-height ratios (WHtR) and serum lipids for all participants. The lipoprotein PNs in 12 subclasses were analyzed using high performance liquid chromatography (HPLC).

RESULTS

Both boys and girls with abdominal obesity (WHtR ≧ 0.5) had significantly higher triglyceride (TG), very-low-density lipoprotein (VLDL)-PN, and all VLDL-subclass PNs compared to those without abdominal obesity. In boys with abdominal obesity, low-density lipoprotein (LDL)-PN was higher, but lipoprotein cholesterol (LDL-C) was not, and high-density lipoprotein cholesterol (HDL-C) was lower, but HDL-PN was not compared to those without abdominal obesity. In girls with abdominal obesity, LDL-C and LDL-PN were not significantly different and both HDL-C and HDL-PN were lower compared to those without abdominal obesity. Subclass analyses demonstrated that boys and girls with abdominal obesity had significantly lower very large and large HDL-PNs than those without abdominal obesity. In addition, medium, small, and very small LDL-PNs were higher in boys with abdominal obesity than those without abdominal obesity.

CONCLUSIONS

This study found that Japanese children with abdominal obesity are affected by the lipoprotein-subclass PN profile, with sex differences in the LDL- and HDL-subclasses, which is different from results obtained by standard serum lipid measurements.

High-Density Lipoprotein Subfractions: Much Ado about Nothing or Clinically Important?

High-density lipoproteins (HDL) are a heterogenous group of plasma molecules with a large variety in composition. There is a wide specter in lipid content and the number of different proteins that has been associated with HDL is approaching 100. Given this heterogeneity and the fact that the total amount of HDL is inversely related to the risk of coronary heart disease (CHD), there has been increasing interest in the function of specific HDL subgroups and in what way measuring and quantifying these subgroups could be of clinical importance in determining individual CHD risk. If certain subgroups appear to be more protective than others, it may also in the future be possible to pharmacologically increase beneficial and decrease harmful subgroups in order to reduce CHD risk. In this review we give a short historical perspective, summarize some of the recent clinical findings regarding HDL subclassifications and discuss why such classification may or may not be of clinical relevance.