High-density lipoprotein subclass and particle size in coronary heart disease patients with or without diabetes

HDL abnormalities in type 2 diabetes: Clinical implications

Atherosclerotic cardiovascular disease (ASCVD) represents the primary cause of mortality among patients with Type 2 Diabetes Mellitus (T2DM). In this population, High-Density Lipoprotein (HDL) particles exhibit abnormalities in number, composition, and function, culminating in diminished anti-atherosclerotic capabilities despite normal HDL cholesterol (HDL-C) concentrations. Hyperglycemic conditions contribute to these alterations in HDL kinetics, composition, and function, causing T2DM patients' HDL particles to exhibit decreased concentrations of diverse lipid species and proteins. Treatment of hyperglycemia has the potential to correct abnormal HDL particle attributes in T2DM; however, pharmacological interventions, including metformin and thiazolidinediones, yield inconsistent outcomes with respect to HDL-C concentrations and functionality. Despite numerous attempts with diverse drugs, pharmacologically augmenting HDL-C levels has not resulted in clinical benefits in mitigating ASCVD risk. In contrast, reducing Low Density Lipoprotein cholesterol (LDL-C) via statins and ezetimibe has demonstrated significant efficacy in curtailing CVD risk among T2DM individuals. Promising results have been observed in animal models and early-phase trials utilizing recombinant HDL and Lecitin Cholesterol Acyl Transferase (LCAT) -enhancing agents, but the evaluation of their efficacy and safety in large-scale clinical trials is ongoing. While aberrant HDL metabolism constitutes a prevalent aspect of dyslipidemia in T2DM, HDL cholesterol concentrations and composition no longer offer valuable insights for informing therapeutic decisions. Nevertheless, HDL metabolism remains a critical research area in T2DM, necessitating further investigation to elucidate the role of HDL particles in the development of diabetes-associated complications.

Lipoprotein Subclasses Independently Contribute to Subclinical Variance of Microvascular and Macrovascular Health

Lipoproteins are important cardiovascular (CV) risk biomarkers. This study aimed to investigate the associations of lipoprotein subclasses with micro- and macrovascular biomarkers to better understand how these subclasses relate to atherosclerotic CV diseases. One hundred and fifty-eight serum samples from the EXAMIN AGE study, consisting of healthy individuals and CV risk patients, were analysed with nuclear magnetic resonance (NMR) spectroscopy to quantify lipoprotein subclasses. Microvascular health was quantified by measuring retinal arteriolar and venular diameters. Macrovascular health was quantified by measuring carotid-to-femoral pulse wave velocity (PWV). Nineteen lipoprotein subclasses showed statistically significant associations with retinal vessel diameters and nine with PWV. These lipoprotein subclasses together explained up to 26% of variation (R2 = 0.26, F(29,121) = 2.80, p < 0.001) in micro- and 12% (R2 = 0.12, F(29,124) = 1.70, p = 0.025) of variation in macrovascular health. High-density (HDL-C) and low-density lipoprotein cholesterol (LDL-C) as well as triglycerides together explained up to 13% (R2 = 0.13, F(3143) = 8.42, p < 0.001) of micro- and 8% (R2 = 0.08, F(3145) = 5.46, p = 0.001) of macrovascular variation. Lipoprotein subclasses seem to reflect micro- and macrovascular end organ damage more precisely as compared to only measuring HDL-C, LDL-C and triglycerides. Further studies are needed to analyse how the additional quantification of lipoprotein subclasses can improve CV risk stratification and CV disease prediction.

Endogenous Protective Factors and Potential Therapeutic Agents for Diabetes-Associated Atherosclerosis

The complications of macrovascular atherosclerosis are the leading cause of disability and mortality in patients with diabetes. It is generally believed that the pathogenesis of diabetic vascular complications is initiated by the imbalance between injury and endogenous protective factors. Multiple endogenous protective factors secreted by endothelium, liver, skeletal muscle and other tissues are recognized of their importance in combating injury factors and maintaining the homeostasis of vasculatures in diabetes. Among them, glucagon-like peptide-1 based drugs were clinically proven to be effective and recommended as the first-line medicine for the treatment of type 2 diabetic patients with high risks or established arteriosclerotic cardiovascular disease (CVD). Some molecules such as irisin and lipoxins have recently been perceived as new protective factors on diabetic atherosclerosis, while the protective role of HDL has been reinterpreted since the failure of several clinical trials to raise HDL therapy on cardiovascular events. The current review aims to summarize systemic endogenous protective factors for diabetes-associated atherosclerosis and discuss their mechanisms and potential therapeutic strategy or their analogues. In particular, we focus on the existing barriers or obstacles that need to be overcome in developing new therapeutic approaches for macrovascular complications of diabetes.

HDL in Atherosclerotic Cardiovascular Disease: In Search of a Role

For a long time, high-density lipoprotein cholesterol (HDL-C) has been regarded as a cardiovascular disease (CVD) protective factor. Recently, several epidemiological studies, while confirming low plasma levels of HDL-C as an established predictive biomarker for atherosclerotic CVD, indicated that not only people at the lowest levels but also those with high HDL-C levels are at increased risk of cardiovascular (CV) mortality. This “U-shaped” association has further fueled the discussion on the pathophysiological role of HDL in CVD. In fact, genetic studies, Mendelian randomization approaches, and clinical trials have challenged the notion of HDL-C levels being causally linked to CVD protection, independent of the cholesterol content in low-density lipoproteins (LDL-C). These findings have prompted a reconsideration of the biological functions of HDL that can be summarized with the word “HDL functionality”, a term that embraces the many reported biological activities beyond the so-called reverse cholesterol transport, to explain this lack of correlation between HDL levels and CVD. All these aspects are summarized and critically discussed in this review, in an attempt to provide a background scenario for the “HDL story”, a lipoprotein still in search of a role.

Improvements in cholesterol efflux capacity of HDL and adiponectin contribute to mitigation in cardiovascular disease risk after bariatric surgery in a cohort with morbid obesity

BACKGROUND

Bariatric surgery can alleviate cardiovascular risk via effects on cardiovascular disease (CVD) risk factors such as diabetes mellitus, hypertension, and dyslipidemia. Our study aimed to assess the cholesterol efflux capacity (CEC) of HDL as a negative risk factor for CVD in individuals with obesity and identify the factors associated with improvement in CEC 3 months following bariatric surgery.

METHODS

We recruited 40 control individuals (mean BMI of 22.2 kg/m²) and 56 obese individuals (mean BMI of 45.9 kg/m²). The biochemical parameters, inflammatory status and CEC of HDL was measured for the obese individuals before bariatric surgery and at 3 months after surgery. The CEC was measured using a cell-based cholesterol efflux system of BODIPY-cholesterol-labelled THP-1 macrophages.

RESULTS

A significant reduction in BMI (- 17%, p < 0.001), resolution of insulin sensitivity (HOMA2-IR = - 23.4%, p = 0.002; Adipo IR = - 16%, p = 0.009) and inflammation [log resistin = - 6%, p = 0.07] were observed 3 months post-surgery. CEC significantly improved 3 months after surgery [Pre: 0.91 ± 0.13; Post: 1.02 ± 0.16; p = 0.001] despite a decrease in HDL-C levels. The change in CEC correlated with the change in apo A-I (r = 0.39, p = 0.02) and adiponectin levels (r = 0.35, p = 0.03).

CONCLUSION

The results suggest that improvements in CEC, through improvement in adipose tissue health in terms of adipokine secretion and insulin sensitivity could be an important pathway in modulating obesity-related CVD risk.

Native High-Density Lipoproteins (HDL) with Higher Paraoxonase Exerts a Potent Antiviral Effect against SARS-CoV-2 (COVID-19), While Glycated HDL Lost the Antiviral Activity

Human high-density lipoproteins (HDL) show a broad spectrum of antiviral activity in terms of anti-infection. Although many reports have pointed out a correlation between a lower serum HDL-C and a higher risk of COVID-19 infection and progression, the in vitro antiviral activity of HDL against SARS-CoV-2 has not been reported. HDL functionality, such as antioxidant and anti-infection, can be impaired by oxidation and glycation and a change to pro-inflammatory properties. This study compared the antiviral activity of native HDL with glycated HDL via fructosylation and native low-density lipoproteins (LDL). After 72 h of fructosylation, glycated HDL showed a typical multimerized protein pattern with an elevation of yellowish fluorescence. Glycated HDL showed a smaller particle size with an ambiguous shape and a loss of paraoxonase activity up to 51% compared to native HDL. The phagocytosis of acetylated LDL was accelerated 1.3-fold by glycated HDL than native HDL. Native HDL showed 1.7 times higher cell viability and 3.6 times higher cytopathic effect (CPE) inhibition activity against SARS-CoV-2 than that of glycated HDL under 60 μg/mL (approximately final 2.2 μM) in a Vero E6 cell. Native HDL showed EC50 = 52.1 ± 1.1 μg/mL (approximately final 1.8 μM) for the CPE and CC50 = 79.4 ± 1.5 μg/mL (around 2.8 μM). The selective index (SI) of native HDL was calculated to be 1.52. In conclusion, native HDL shows potent antiviral activity against SARS-CoV-2 without cytotoxicity, while the glycation of HDL impairs its antiviral activity. These results may explain why patients with diabetes mellitus or hypertension are more sensitive to a COVID-19 infection and have a higher risk of mortality.

Structure dynamics of ApoA-I amyloidogenic variants in small HDL increase their ability to mediate cholesterol efflux

Apolipoprotein A-I (ApoA-I) of high density lipoproteins (HDLs) is essential for the transportation of cholesterol between peripheral tissues and the liver. However, specific mutations in ApoA-I of HDLs are responsible for a late-onset systemic amyloidosis, the pathological accumulation of protein fibrils in tissues and organs. Carriers of these mutations do not exhibit increased cardiovascular disease risk despite displaying reduced levels of ApoA-I/HDL cholesterol. To explain this paradox, we show that the HDL particle profiles of patients carrying either L75P or L174S ApoA-I amyloidogenic variants show a higher relative abundance of the 8.4-nm versus 9.6-nm particles and that serum from patients, as well as reconstituted 8.4- and 9.6-nm HDL particles (rHDL), possess increased capacity to catalyze cholesterol efflux from macrophages. Synchrotron radiation circular dichroism and hydrogen-deuterium exchange revealed that the variants in 8.4-nm rHDL have altered secondary structure composition and display a more flexible binding to lipids than their native counterpart. The reduced HDL cholesterol levels of patients carrying ApoA-I amyloidogenic variants are thus balanced by higher proportion of small, dense HDL particles, and better cholesterol efflux due to altered, region-specific protein structure dynamics.

Exercise Training Induced Changes In Nuclear Magnetic Resonance-Measured Lipid Particles In Mild Cognitively Impaired Elderly African American Volunteers: A Pilot Study

Purpose

Poor cardiorespiratory fitness (CRF) is linked to cognitive deterioration, but its effects on lipid heterogeneity and functional properties in older African American (AA) subjects with mild cognitive impairment (MCI) need elucidation. This study determined whether exercise training-induced changes in blood lipid particle sizes (LPS) were associated with CRF determined by VO₂Max in elderly AAs with MCI. Given the pivotal role of brain-derived neurotrophic factor (BDNF) on glucose metabolism, and therefore, “diabetic dyslipidemia”, we also determined whether changes in LPS were associated with the levels of serum BDNF.

Methods

This analysis included 17 of the 29 randomized elderly AAs with MCI who had NMR data at baseline and after a 6-month training. We used Generalized Linear Regression (GLM) models to examine cardiorespiratory fitness (VO₂Max) effects on training-induced change in LPS in the stretch and aerobic groups. Additionally, we determined whether the level of BDNF influenced change in LPS.

Results

Collectively, mean VO₂Max (23.81±6.17) did not differ significantly between aerobic and stretch groups (difference=3.17±3.56, P=0.495). Training-related changes in very low-density lipoprotein, chylomicrons, and total low-density lipoprotein (LDL) particle sizes correlated significantly with VO₂Max, but not after adjustment for age and gender. However, increased VO₂Max significantly associated with reduced total LDL particle size after similar adjustments (P = 0.046). While stretch exercise associated with increased protective large high-density lipoprotein particle size, the overall effect was not sustained following adjustments for gender and age. However, changes in serum BDNF were associated with changes in triglyceride and cholesterol transport particle sizes (P < 0.051).

Conclusion

Promotion of stretch and aerobic exercise to increase CRF in elderly AA volunteers with MCI may also promote beneficial changes in lipoprotein particle profile. Because high BDNF concentration may reduce CVD risk, training-related improvements in BDNF levels are likely advantageous. Large randomized studies are needed to confirm our observations and to further elucidate the role for exercise therapy in reducing CVD risk in elderly AAs with MCI.

Oestradiol: any role in cardiovascular risk factors in female centenarians of Hainan?

Background

Previous studies reported that low level of oestradiol (E2) was associated with higher risk of cardiovascular disease (CVD). However, little study examined the relationship between E2 and CVD in longevous women, which were deficient in serum E2 for the post-menopausal status. Therefore, this study aims to explore the association between E2 and CVD risk factors in a group of female centenarians of Hainan, China.

Methods

A total of 413 female centenarians (aged from 100 to 115) from China Hainan Centenarian Cohort Study (CHCCS) were enrolled in this study. Home interviews were conducted to collected data on demographic characteristics, health-related lifestyles, and anthropometrics. The level of serum E2 was assessed in the Clinical Laboratory of Hainan branch of PLA General Hospital. The variables of CVD risk factors, including blood pressures, lipids and blood glucose, were measured through standard procedures.

Results

Significant negative correlations between levels of serum E2 and TC, HDL-C, and LDL-C were observed in this study. Compared with the highest group of E2, the odds ratio and 95% confidence intervals of high LDL-C in groups 3, 2 and 1 were OR1.94 (CI0.82–4.62), OR3.61 (CI1.27–10.25) and OR9.29 (CI2.08–41.53), respectively. Similarly, the prevalence of hypertension was decreased with the increase of serum E2. The odds ratio and 95% confidence intervals of stage-2 hypertension in groups 3, 2 and 1 versus highest E2 group were OR1.34 (CI0.49–3.72), OR1.36 (CI0.47–3.99) and OR1.38 (CI0.45–4.20), respectively.

Conclusions

This study examined the relationship between E2 and CVD risk factors in a group of community-based female centenarians. A negative correlations between serum E2 levels and CVD risk factors, i.e. high level of LDL-C, TC, and hypertension were observed in this population. Besides, the level of serum E2 is also negatively correlated with HDL-C. Further studies on the correlation between serum E2 and CVD risk factors, especially dyslipidemia, in longevous and post-menopausal women are warranted.

The Role of High-Density Lipoproteins in Diabetes and Its Vascular Complications

Almost 600 million people are predicted to have diabetes mellitus (DM) by 2035. Diabetic patients suffer from increased rates of microvascular and macrovascular complications, associated with dyslipidaemia, impaired angiogenic responses to ischaemia, accelerated atherosclerosis, and inflammation. Despite recent treatment advances, many diabetic patients remain refractory to current approaches, highlighting the need for alternative agents. There is emerging evidence that high-density lipoproteins (HDL) are able to rescue diabetes-related vascular complications through diverse mechanisms. Such protective functions of HDL, however, can be rendered dysfunctional within the pathological milieu of DM, triggering the development of vascular complications. HDL-modifying therapies remain controversial as many have had limited benefits on cardiovascular risk, although more recent trials are showing promise. This review will discuss the latest data from epidemiological, clinical, and pre-clinical studies demonstrating various roles for HDL in diabetes and its vascular complications that have the potential to facilitate its successful translation.

Effect of short term aerobic exercise on fasting and postprandial lipoprotein subfractions in healthy sedentary men

Background

Our goal was to investigate the effect of short term exercise on fasting and postprandial lipoprotein profile.

Methods

Healthy sedentary men exercised 20 min for four days. The intensity of exercise was modulated to maintain 75–80 % of a calculated HRmax. Before and after the exercise program, fasting and postprandial (4 h after standard meal) concentrations of lipoprotein subfractions were measured by an electrophoresis in polyacrylamide gel and total concentrations of TAG, LDL and HDL by enzymatic colorimetric method. After 2 days of rest, fasting and postprandial concentrations of lipoprotein fractions and subfractions were measured to determine a persistency of a changes in the lipoprotein profile.

Results

4 days of physical exercise led to statistically significant decrease of concentration of triacylglycerol in fasting (76.29 ± 20.07, 53.92 ± 10.90, p < 0.05) and postprandial state (139.06 ± 23.72, 96.55 ± 25.21, p < 0.05) VLDL in fasting (21.88 ± 3.87, 18.00 ± 3.93, p < 0.05) and postprandial state (23.88 ± 3.52, 19.25 ± 3.62, p < 0.05), total cholesterol in fasting (162.26 ± 23.38, 148.91 ± 17.72, p < 0.05) and postprandial state (163.73 ± 23.02, 150.08 ± 18.11, p < 0.05). Atherogenic medium LDL decreased also in fasting (9.89 ± 3.27, 6.22 ± 2.55, p < 0.001) and postprandial state (8.88 ± 6.51, 6.88 ± 5.57, p < 0.001). However decrease of large IDL (25.38 ± 3.54, 23.88 ± 3.91, p < 0.05) and large LDL particles (42.89 ± 11.40, 38.67 ± 9.30) was observed only in postprandial state. Total HDL concentration remained unchanged but we observed statistically significant decrease of small HDL particles in fasting (6.11 ± 2.89, 4.22, p < 0.05) and postprandial state (6.44 ± 3.21, 4.56 ± 1.33, p < 0.05). Concentration of these particles are associated with progression of atherosclerosis. All changes of fasting and postprandial lipoprotein profile disappeared after 2 days of rest.

Conclusion

Just 4 daily settings of 20 min of physical exercise can lead to significant positive changes of fasting and postprandial lipoprotein profile.

Oxidized high-density lipoprotein accelerates atherosclerosis progression by inducing the imbalance between treg and teff in LDLR knockout mice

High density lipoprotein (HDL) dysfunction has been widely reported in clinic, and oxidation of HDL (ox-HDL) was shown to be one of the most common modifications in vivo and participate in the progression of atherosclerosis. But the behind mechanisms are still elusive. In this study, we firstly analyzed and found strong relationship between serum ox-HDL levels and risk factors of coronary artery diseases in clinic, then the effects of ox-HDL in initiation and progression of atherosclerosis in LDLR knockout mice were investigated by infusion of ox-HDL dissolved in chitosan hydrogel before the formation of lesions in vivo. Several new evidence were shown: (i) the serum levels of ox-HDL peaked early before the formation of lesions in LDLR mice fed with high fat diet similar to oxidative low density lipoprotein, (ii) the formation of atherosclerotic lesions could be accelerated by infusion of ox-HDL, (iii) the pro-atherosclerotic effects of ox-HDL were accompanied by imbalanced levels of effector and regulatory T cells and relative gene expressions, which implied that imbalance of teff and treg might contribute to the pro-atherosclerosis effects of ox-HDL.

Relationship between plasma phospholipase A2 concentrations and lipoprotein subfractions in patients with stable coronary artery disease

BACKGROUND

Both increased lipoprotein-associated phospholipase A2 (Lp-PLA2) concentrations and atherogenic lipoprotein subfractions have been shown to reflect unfavourable cardiovascular risk. However, the correlation between Lp-PLA2 and lipoprotein subfractions in patients with coronary artery disease (CAD) has not been assessed yet.

METHODS

A total of 324 consecutive subjects who were not treated with lipid-lowering drugs were enrolled (angiographically proven CAD: n = 253; non-CAD: n = 71). Plasma Lp-PLA2 concentrations were measured using ELISA. The low-density lipoprotein (LDL) and high-density lipoprotein (HDL) subfractions were determined by Lipoprint System.

RESULTS

Plasma Lp-PLA2 concentrations were higher in patients with CAD compared with those without CAD (153.61 ± 78.73 vs. 131.41 ± 65.49 ng/ml, p = 0.028). The univariable correlation analysis revealed that Lp-PLA2 concentrations were positively correlated with the cholesterol concentrations of each LDL subfractions and the intermediate as well as small HDL subfractions, while negatively linked with the LDL particle size and large HDL-cholesterol (HDL-C) concentrations in CAD group. However, no similar results were observed in the non-CAD group. Furthermore, multivariable regression analysis was performed in patients with CAD and showed that plasma Lp-PLA2 concentrations were independently correlated with the cholesterol concentrations of each LDL subfractions [large LDL-cholesterol (LDL-C): β = 0.263, p < 0.001; intermediate LDL-C: β = 0.327, p < 0.001; small LDL-C: β = 0.135, p = 0.033] and small HDL-C (β = 0.133, p = 0.034).

CONCLUSION

Lp-PLA2 concentrations were positively associated with all LDL subfractions and small HDL subfraction, suggesting an interaction between Lp-PLA2 and lipoprotein subfraction phenotypes in the status of CAD.

High density lipoproteins: Measurement techniques and potential biomarkers of cardiovascular risk

Plasma high density lipoprotein cholesterol (HDL) comprises a heterogeneous family of lipoprotein species, differing in surface charge, size and lipid and protein compositions. While HDL cholesterol (C) mass is a strong, graded and coherent biomarker of cardiovascular risk, genetic and clinical trial data suggest that the simple measurement of HDL-C may not be causal in preventing atherosclerosis nor reflect HDL functionality. Indeed, the measurement of HDL-C may be a biomarker of cardiovascular health. To assess the issue of HDL function as a potential therapeutic target, robust and simple analytical methods are required. The complex pleiotropic effects of HDL make the development of a single measurement challenging. Development of laboratory assays that accurately HDL function must be developed validated and brought to high-throughput for clinical purposes. This review discusses the limitations of current laboratory technologies for methods that separate and quantify HDL and potential application to predict CVD, with an emphasis on emergent approaches as potential biomarkers in clinical practice.

High-density lipoprotein subfractions in relation with the severity of coronary artery disease: A Gensini score assessment

BACKGROUND

The exact role of different high-density lipoprotein (HDL) subfractions in the pathogenesis of coronary artery disease (CAD) has not yet been fully explored. The aim of the present study was to examine the relationship between HDL subfractions and the severity of CAD in patients without statin therapy.

METHODS

A total of 382 consecutive patients (mean: 55.36 ± 11.30 years of age) who underwent coronary angiography from angina-like chest pain were investigated. Patients were classified into 2 groups according to the angiographic results: a CAD group (n = 283) and a control group (n = 99). The distribution of HDL subfractions was analyzed using a Quantimetrix Lipoprint HDL system. CAD severity was measured by Gensini score (GS).

RESULTS

Compared with the control group, HDL-cholesterol (HDL-C), large HDL-C level, and the large HDL subfraction percentages in the CAD group were significantly lower (P = .002, P < .001, P < .001, respectively). Meanwhile, a small HDL-C level and the percentage of small HDL subfraction were significantly higher (P = .003, P < .001, respectively). Correlation analysis showed that the percentage of a large HDL subfraction was negatively correlated with GS (β = -0.191, P = .005), whereas the percentage of a small HDL subfraction positively correlated with GS (β = 0.145, P = .023) in patients with CAD.

CONCLUSIONS

Small HDL subfraction was associated with the presence of CAD, whereas the percentage of large HDL and small HDL subfraction was negatively and positively associated with the severity of CAD, respectively.

Small high-density lipoprotein (HDL) subclasses are increased with decreased activity of HDL-associated phospholipase A₂ in subjects with prediabetes

Alterations in high-density lipoprotein (HDL) subclass distribution, as well as in the activities of HDL-associated enzymes, have been associated with increased cardiovascular disease (CVD) risk. HDL subclass distribution and the activities of HDL-associated enzymes remain unknown in prediabetic patients, a condition also associated with increased CVD risk. The aim of the present study was to assess any differences in HDL subclass distribution (using polyacrylamide gel electrophoresis) and in activities of HDL-associated enzymes between prediabetic (impaired fasting glucose, IFG, n = 80) and non-prediabetic subjects (n = 105). Subjects with prediabetes had significantly increased waist circumference, blood pressure and triacylglycerol (TAG) levels compared with subjects with fasting glucose levels <100 mg/dL (all p < 0.05). The proportion of small HDL3 over HDL cholesterol (HDL-C) was significantly increased in prediabetic subjects compared with their controls (p < 0.05). The activity of the anti-atherogenic HDL-associated lipoprotein-associated phospholipase A₂ (HDL-LpPLA₂) was significantly lower in subjects with prediabetes (p < 0.05), whereas the activity of paraoxonase 1 (using both paraoxon and phenyl acetate as substrates) did not significantly differ between subjects with or without prediabetes. In a stepwise linear regression analysis, the proportion of small HDL3 over HDL-C concentration was independently associated with the presence of prediabetes and with total cholesterol and TAG concentration (positively), as well as with HDL-C levels (negatively). We also observed a trend of increased small dense low-density lipoprotein cholesterol levels in prediabetic subjects compared with their controls. Subjects with IFG exhibit increased proportion of small HDL3 particles combined with decreased activity of the anti-atherogenic HDL-LpPLA₂.

Relationship between the distribution of plasma HDL subclasses and the polymorphisms of APOA5 in hypertriglyceridemia

AIMS

This study aims to examine the possible associations between high density lipoprotein (HDL) subclass distribution and APOA5-1131T>C polymorphism in hypertriglyceridemia.

METHODS

The distribution of HDL subclasses was quantified by 2-dimensional electrophoresis in conjunction with immunodetection method. The APOA5-1131T>C polymorphism was identified in 95 hypertriglyceridemic (HTG) patients and 102 healthy subjects by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP).

RESULTS

The APOA5-1131C (C) allele frequency was higher in the HTG group than in the control group. Plasma triglycerides (TG) were significantly higher and apoA5 was significantly lower in patients with the C allele when compared to patients with the APOA5-1131T (T) allele, even more dramatically so in the APOA5-1131CC homozygote. In both the HTG group and the control group, the frequency of the C allele was positively correlated with levels of TG, total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and apolipoprotein B100 (apoB100), and negatively correlated with levels of high density lipoprotein cholesterol (HDL-C), apolipoprotein A1 (apoA1) and apolipoprotein A5 (apoA5) (P<0.001). In all subjects, the frequency of the C allele was positively correlated with the level of small-sized HDL (preβ(1)-HDL and HDL(3a)), and negatively correlated with levels of HDL(2a) and HDL(2b).

CONCLUSION

Changes in HDL subclass distributions in HTG may be related to the APOA5-1131T>C polymorphism. This polymorphism leads to a general shift towards smaller-sized HDL.

High-density lipoprotein subfractions--what the clinicians need to know

Although the inverse relationship between plasma levels of high-density lipoprotein (HDL) and cardiovascular disease has been largely demonstrated, many observations have suggested that the assessment of HDL functionality might be more informative than a simple measurement of HDL-cholesterol plasma levels. HDLs are a class of structurally and functionally heterogeneous particles; in atherosclerosis-related diseases, changes in HDL subfraction levels and functions are frequently observed. Circulating levels of large HDL particles are decreased in dyslipidaemic conditions, while levels of small dense HDL particles are increased in patients with coronary heart disease. Furthermore, specific genetic defects in proteins involved in HDL metabolism significantly impact the distribution of HDL subpopulations. Finally, many drugs used for dyslipidaemia induce changes in HDL subfractions strictly related to cardiovascular disease. Although several methods exist to evaluate HDL subclass levels, most of them are not easily applicable in clinical practice, due to the costs and high variability. However, the possibility to measure the levels of specific HDL subfractions in patients with atherosclerosis-related diseases might help to better define their cardiovascular risk.