HDL-cholesterol Subfractions Research Articles

HDL-Cholesterol Subfraction Dimensional Distribution Is Associated with Cardiovascular Disease Risk and Is Predicted by Visceral Adiposity and Dietary Lipid Intake in Women.

HDL-cholesterol quality, including cholesterol distribution in HDL subfractions, is emerging as a key discriminant in dictating the effects of these lipoproteins on cardiovascular health. This study aims at elucidating the relationship between cholesterol distribution in HDL subfractions and CVD risk factors as well as diet quality and energy density in a population of pre- and postmenopausal women. Seventy-two women aged 52 ± 6 years were characterized metabolically and anthropometrically. Serum HDL-C subfractions were quantified using the Lipoprint HDL System. Cholesterol distribution in large HDL subfractions was lower in overweight individuals and study participants with moderate to high estimated CVD risk, hypertension, or insulin resistance. Cholesterol distribution in large, as opposed to small, HDL subfractions correlated negatively with insulin resistance, circulating triglycerides, and visceral adipose tissue (VAT). VAT was an independent positive and negative predictor of cholesterol distribution in large and small HDL subfractions, respectively. Furthermore, an increase in energy intake could predict a decrease in cholesterol levels in large HDL subfractions while lipid intake positively predicted cholesterol levels in small HDL subfractions. Cholesterol distribution in HDL subfractions may represent an additional player in shaping CVD risk and a novel potential mediator of the effect of diet on cardiovascular health.

Diverse impacts of red palm olein, extra virgin coconut oil and extra virgin olive oil on cardiometabolic risk markers in individuals with central obesity: a randomised trial.

Dietary fats with an abundance of phytonutrients have garnered public attention beyond fatty acids per se. This study was set to investigate the impact of consuming diets with red palm olein (RPOO), extra virgin coconut oil (EVCO) and extra virgin olive oil (EVOO, as a control) on cardiometabolic risk biomarkers and lipid profile. We recruited a total of 156 individuals with central obesity, aged 25-45years, with waist circumference ≥ 90cm for men and ≥ 80cm for women in a parallel single-blind 3-arm randomised controlled trial. The participants consumed isocaloric diets (~ 2400kcal) enriched with respective test fats (RPOO, EVCO or EVOO) for a 12-week duration. The mean of the primary outcome plasma high sensitivity C-reactive protein was statistically similar between the three diets after a 12-week intervention. EVOO resulted in significantly lower mean LDL cholesterol compared with RPOO and EVCO, despite similar effects on LDL and HDL cholesterol subfractions. The RPOO diet group showed elevated mean and -carotenes levels compared with EVCO and EVOO diet groups (P < 0.05), corresponding with the rich carotenoid content in RPOO. The three oils, each of which has unique phytonutrient and fatty acid compositions, manifested statistically similar cardiometabolic effects in individuals with central obesity at risk of developing cardiovascular diseases with distinct circulating antioxidant properties. ClinicalTrials.gov (NCT05791370).

Lipid Profile, Lipoprotein Subfractions, and Fluidity of Membranes in Children and Adolescents with Depressive Disorder: Effect of Omega-3 Fatty Acids in a Double-Blind Randomized Controlled Study.

Depressive disorder (DD) is a psychiatric disorder whose molecular basis is not fully understood. It is assumed that reduced consumption of fish and omega-3 fatty acids (FA) is associated with DD. Other lipids such as total cholesterol (TCH), LDL-, and HDL-cholesterols (LDL-CH, HDL-CH) also play a role in depression. The primary endpoint of the study was the effect of omega-3 FA on the severity of depression in children and adolescents. This study aimed to investigate the secondary endpoint, relationship between depressive disorder symptoms and lipid profile, LDL- and HDL-cholesterol subfractions, Paraoxonase 1 (PON1) activities, and erythrocyte membrane fluidity in 58 depressed children and adolescents (calculated by the statistical program on the effect size), as well as the effect of omega-3 FA on the monitored parameters. Depressive symptoms were assessed by the Children’s Depression Inventory (CDI), lipid profile by standard biochemical procedures, and LDL- and HDL-subfractions by the Lipoprint system. Basic biochemical parameters including lipid profile were compared with levels in 20 healthy children and were in the physiological range. Improvement of symptoms in the group supplemented with a fish oil emulsion rich in omega-3 FA in contrast to omega-6 FA (emulsion of sunflower oil) has been observed. We are the first to report that omega-3 FAs, but not omega-6 FA, increase large HDL subfractions (anti-atherogenic) after 12 weeks of supplementation and decrease small HDL subfractions (proatherogenic) in depressed children. We found a negative correlation between CDI score and HDL-CH and the large HDL subfraction, but not LDL-CH subfractions. CDI score was not associated with erythrocyte membrane fluidity. Our results suggest that HDL-CH and its subfractions, but not LDL-CH may play a role in the pathophysiology of depressive disorder. The study was registered under ISRCTN81655012.

Effect of weight loss on cardiometabolic risk factors in obese patients

Abstract Background Central obesity and dyslipidemia are a cardinal features of the metabolic syndrome and represents increased cardiometabolic risk. It has been shown that weight loss is capable to improve insulin sensitivity and lipid parameters. The aim of our study was to analyze the effect of a weight-lowering program (diet and physical activity) on LDL- and HDL-cholesterol subfractions and cardiometabolic risk factors (waist circumference, blood pressure, insulin sensitivity, physical fitness). Methods We studied 2 groups of obese subjects, group A composed of 43 patients with obesity grade 1 and 2 (30F/13M; age: 43.2 ±12.4 years; BMI 31.3 ± 6.1 kg/m2); group B composed of patients with obesity grade 3 (6F/7M; age: 34.7 ±9.8 years; BMI 51.7 ± 7.9 kg/m2). The weight loss interventional program (NCT02325804) in duration of 8-week (group A) or 24 weeks (group B) consisted of hypocaloric diet and physical activity. Body composition, physical fitness, blood lipids profile (using the Lipoprint system (Quantimetrix Corp., CA, USA), and insulin sensitivity were measured. Results The average weight loss was 7.3±1.9 kg in group A and 35.3±16.0 kg in group B. Systolic, diastolic blood pressure (BP) as well as heart rate decreased in group A, in group B only systolic BP. Fasting plasma glucose and insulin decreased as well as insulin sensitivity and physical fitness has been improved after intervention. Total, LDL2, HDL2 cholesterol, as well as triglycerides (TG) decreased with weight in group A and total, LDL, TG, VLDL, LDL2 large, and small HDL subfractions decreased and intermediate HDL increased in group B. Conclusions Short term life style intervention (diet and physical activity) in patients with obesity lead to notable improvement of cardiometabolic parameters (decreased body fat mass, improved insulin sensitivity, lipid profile) as well as atheroprotective changes in LDL subfractions. Funding Supported by grants APVV 17-0099; VEGA 2/0129/20; VEGA 2/0072/18 Key messages Short term life style intervention in patients with obesity lead to notable improvement of cardiometabolic parameters. Weight-lowering program (diet and physical activity) lead to positive changes in LDL- and HDL-cholesterol subfractions.

Lipoprotein profiling in early multiple sclerosis patients: effect of chronic inflammation?

BackgroundInflammatory cytokines contribute to proatherogenic changes in lipid metabolism by reduction of HDL-cholesterol (HDL-C) levels, impairment of its antiinflammatory and antioxidant functions. Therefore, the protective actions of HDL-C can be limited in chronic inflammatory diseases such as multiple sclerosis (MS). The aim of this study was to assess the association between lipoprotein subfractions and inflammatory status in early stages of multiple sclerosis.MethodsPolyacrylamide gel electrophoresis Lipoprint© System was used for lipoprotein profile analysis in 19 newly diagnosed MS patients, and in matched 19 healthy controls. Serum levels of interleukin (IL) 1β, IL-2, IL-4, IL-5, IL-6, IL-7, IL-8, IL-10, IL-12 (p70), IL-13, IL-17, granulocyte colony-stimulating factor (G-CSF), granulocyte-macrophage colony-stimulating factor, interferon-γ and TNF-α were measured by multiplex bead assay.ResultsConcentrations of the measured cytokines and lipoprotein subclasses were comparable between MS patients and controls. Male, but not female MS patients had significantly higher total HDL-C and small HDL-C subfraction than healthy controls. Large HDL-C negatively correlated with all measured cytokines except IL-17 in MS but not in controls. Intermediate HDL-C subfractions correlated positively with all measured cytokines except G-CSF in MS females but not in MS males or controls.ConclusionOur results of higher HDL-C and mainly its small HDL-C subfraction suggest that male MS patients are at higher risk of atherosclerosis and the subtle dyslipidemia is present in early stages of the disease. The correlations between specific HDL-C subfractions and the inflammatory cytokines demonstrate mutual links between systemic inflammation and lipid metabolism in MS.Trial registrationClinicalTrials.gov, Identifier: NCT 03052595 Registered on Feb 14, 2017.

HIGH DENSITY LIPOPROTEIN SUBFRACTIONS ARE ASSOCIATED WITH COGNITIVE PERFORMANCE: A CROSS-SECTIONAL ANALYSIS

There are conflicting results about the high-density lipoproteins (HDL) role in cognitive performance. Since HDL is composed of different subfractions that have different characteristics, our study sought to observe cross-sectionally the association between HDL-cholesterol subfractions and domain-

Effect of 8-weeks intensive lifestyle intervention on LDL and HDL subfractions

ObjectiveAtherogenic dyslipidemia is a cardinal feature of obesity and the metabolic syndrome, which increases the risk of cardiovascular diseases. Many interventional studies, describing the influence of weight loss on cardiometabolic risks, are bariatric surgery studies. The aim of our study was to analyze the effect of intensive lifestyle changes on LDL- and HDL-cholesterol subfractions and cardiometabolic risk factors in obese subjects. MethodsA group of 41 patients with obesity (11M/30F; 44.1±12.4 years; BMI 30.2±6.3kg/m2) participated in an 8-week weight loss interventional program (NCT02325804), consisting of caloric intake reduced by 30% and physical activity (150min/week). Insulin sensitivity was evaluated according to the homeostasis model assessment of insulin resistance (HOMA-IR) and physical fitness was measured using bicycle ergometry. Lipid subfractions were measured using the Lipoprint system (Quantimetrix Corp., CA, USA). ResultsAfter the intervention, body weight was reduced by 5.4±4.5kg, as well as body fat mass and waist circumference. Physical fitness improved, systolic and diastolic blood pressure as well as heart rate decreased after the intervention. Insulin sensitivity improved after the intervention. Total, LDL, HDL cholesterol, as well as triglycerides decreased after the intervention. Regarding the lipoprotein subfractions, LDL2 and small HDL subfractions decreased, while others have not changed. ConclusionEight weeks of diet and physical activity intervention led to weight and fat mass loss and induced improvement of insulin sensitivity, as well as atheroprotective changes of lipid profile. However, the weight loss associated changes in cholesterol subfractions as cardiovascular risk biomarkers deserve further studies.

NMR-measured subfractions of HDL-cholesterol through thyroid function spectrum

NMR-measured subfractions of HDL-cholesterol through thyroid function spectrum

Effects of Hypoxia and Bed Rest on Markers of Cardiometabolic Risk: Compensatory Changes in Circulating TRAIL and Glutathione Redox Capacity.

In chronic diseases, hypoxia and physical inactivity are associated with atherosclerosis progression. In contrast, a lower mortality from coronary artery disease and stroke is observed in healthy humans residing at high altitude in hypoxic environments. Eleven young, male volunteers completed the following 10-day campaigns in a randomized order: hypoxic ambulatory, hypoxic bed rest and normoxic bed rest. Before intervention, subjects were evaluated in normoxic ambulatory condition. Normobaric hypoxia was achieved in a hypoxic facility simulating 4000 m of altitude. Following hypoxia, either in bed rest or ambulatory condition, markers of cardiometabolic risk shifted toward a more atherogenic pattern consisting of: (a) lower levels of total HDL cholesterol and HDL2 sub-fraction and decreased hepatic lipase; (b) activation of systemic inflammation, as determined by C-reactive protein and serum amyloid A; (c) increased plasma homocysteine; (d) decreased delta-5 desaturase index in cell membrane fatty acids, a marker of insulin sensitivity. Bed rest and hypoxia additively decreased total HDL and delta-5 desaturase index. In parallel to the pro-atherogenic effects, hypoxia activated selected anti-atherogenic pathways, consisting of increased circulating TNF-related apoptosis-inducing ligand (TRAIL), a protective factor against atherosclerosis, membrane omega-3 index and erythrocyte glutathione availability. Hypoxia mediated changes in TRAIL concentrations and redox glutathione capacity (i.e., GSH/GSSG ratio) were greater in ambulatory conditions (+34 ± 6% and +87 ± 31%, respectively) than in bed rest (+17 ± 7% and +2 ± 27% respectively). Hypoxia-induced cardiometabolic risk is blunted by moderate level of physical activity as compared to bed rest. TRAIL and glutathione redox capacity may contribute to the positive interaction between physical activity and hypoxia.Highlights:– Hypoxia and bed rest activate metabolic and inflammatory markers of atherogenesis.– Hypoxia and physical activity activate selected anti-atherogenic pathways.– Hypoxia and physical activity positive interaction involves TRAIL and glutathione.

Abstract P195: High-density Lipoprotein Subfractions Are Associated With Low-grade Inflammation, Insulin Resistance and Metabolic Syndrome Components: The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

Background: HDL cholesterol (HDL-C) can be divided into subfractions, which may have variable association with atherogenic process. There are mixed results about the association between HDL-C subfractions and risk factors for cardiovascular disease. Hypothesis: HDL-C subfractions have different associations with metabolic syndrome, low-grade inflammation and insulin resistance. Methods: 4,532 individuals between 35 and 74 years without previous cardiovascular disease not in use of fibrates were enrolled. HDL-C subfractions were separated by vertical ultracentrifugation (Vertical Auto Profile - in mg/dl) in HDL 2 -C and HDL 3 -C. HDL 2 -C/HDL 3 -C ratio, insulin resistance (HOMA-IR) and high-sensitivity C-reactive protein (CRP) were also included in the analysis. Results: The mean age was 51 ± 9 years, and 54.8% were women. In univariate analysis, HDL-C, HDL 2 -C, and HDL 3 -C were all inversely associated with each of the MetS defining factors, HOMA-IR values, and serum CRP. It was also observed a negative association between HDL 2 -C/HDL 3 -C ratio with the variables mentioned above even after adjusting for smoking, alcohol use, physical activity, and HDL-C levels (p &lt;0.01). Conclusion: HDL-C and both subfractions are inversely associated with all the factors that define MetS, insulin resistance and low-grade inflammation. Additionally, the HDL 2 -C/HDL 3 -C subfractions ratio assessed by VAP is also significantly associated with the former factors even after further adjustment for total HDL-C and other confounding variables.

Gender differences in LDL- and HDL-cholesterol subfractions in patients after the acute ischemic stroke and their association with oxidative stress markers.

The aim of our study was to examine gender differences of LDL- and HDL-cholesterol subfractions in patients after the acute ischemic stroke with focus on small LDL and HDL subfractions, and their association with oxidative stress markers. In addition, we have monitored the 7-day effect of cholesterol-lowering drugs administered to patients after the acute ischemic stroke, on these subfractions. Eighty two stroke patients and 81 age matched controls were included in this study. Blood was collected from patients within 24 h after the stroke (group A) and re-examined at the 7-day follow-up (group B). We have found gender differences in LDL- and HDL-subfractions in stroke patients, lipid-lowering drugs administered to acute ischemic stroke patients significantly reduced all measured parameters of lipoprotein profile. In the group A LDL1 subfraction positively correlated with activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione peroxidase) indicating a protective role of this subfraction. On the contrary, small HDL subfractions positively correlated with lipoperoxide levels and negatively with trolox equivalent antioxidant capacity in plasma suggesting a negative role of these subfractions. In this work we have confirmed the hypothesis of atherogenic properties of small HDL subfractions and anti-atherogenic properties of large LDL1-subfractions.

Tobacco Smoke Exposure Reduces Paraoxonase Activity in a Murine Model

AIM: To demonstrate a direct inhibitory effect of cigarette smoke exposure on paraoxonase 1 activity in a murine in vivo model. METHODS: At 8 weeks old, we randomized 10 C57/bl6 mice to an environment consisting of either filtered air or cigarette smoke for 6 months. Smoke exposure (7 hours per day, 5 days per week) was standardized using a model TE-10 smoking machine and adjusted to maintain constant sidestream and mainstream smoke. After 6 months of exposure, we assessed differences in lung air space, cholesterol, lipid, and lipoprotein profiles, as well as paraoxonase activity in mice exposed to cigarette smoke extract compared to unexposed control mice. RESULTS: Cigarette smoke exposure by the protocol used was sufficient to result in pathologic changes in lung architecture consistent with emphysema. Specifically, we observed that mice exposed to cigarette smoke had a significantly higher mean linear chord length compared to animals that were exposed to filtered air (p&lt;0.02). Despite this exposure, no differences in total HDL-cholesterol levels or HDL-cholesterol sub-fractions (i.e. HDL2 and HDL3 fractions) were noted between smoke-exposed and unexposed animals (p=1.00, 0.6, and 0.4, respectively). Notably, mean HDL-cholesterol levels were identical between groups (92.8 vs 92.8 mg/dL, p=1.0). Paraoxonase activity, however, was markedly reduced in mice exposed to cigarette smoke compared to those who were not exposed (102, SD=9.6 vs 144, SD=4.1 units of activity, respectively, p=0.002). CONCLUSION: In this murine model, tobacco smoke exposure directly inhibits paraoxonase activity independently of HDL-cholesterol levels rather than indirectly via reduction in HDL-cholesterol levels.

Associations between follicular fluid high density lipoprotein particle components and embryo quality among in vitro fertilization patients.

Follicular redox balance is likely to be important for embryo quality during in vitro fertilization (IVF), and the anti-oxidative high desity lipoprotein (HDL) particle is the sole lipoprotein measured in follicular fluid (FF). Therefore, we investigated FF HDL particle components as predictors of embryo quality during IVF. Two research follicles collected from each participant were individually tracked, and 103 women having at least one developed embryo were included in the analysis. Concentrations of 15 non-cholesterol HDL particle components and 26 HDL-cholesterol (HDL-C) particle size subfractions were determined. Embryo quality was assessed for embryo cell number, embryo fragmentation, and embryo symmetry. Multivariable Poisson regression with a sandwich variance estimator was used to evaluate associations between HDL particle components and embryo quality, adjusted for covariates. Higher γ-tocopherol concentration was associated with less embryo fragmentation (relative risk [RR] = 4.43; 95% confidence interval [CI] 1.78, 11.06), and higher apolipoprotein A-1 concentration was associated with full embryo symmetry (RR = 3.92; 95% CI 1.56, 9.90). Higher concentrations of HDL-C subfractions in the large and medium particle size ranges were associated with poorer embryo quality. FF HDL lipophilic micronutrients and protein components, as well as HDL-C particle size, may be important predictors of embryo quality during IVF.

Abstract MP42: Subfractions of High-density Lipoprotein Cholesterol and Carotid Intima-media Thickness

Background and Purpose: Recent drug trials have challenged the “HDL-cholesterol anti-atherosclerotic hypothesis”, suggesting that total levels of HDL-C may not be best target for intervention. HDL-cholesterol (HDL-C) subfractions may be better markers of vascular risk than total levels of HDL-C. The objective of this cross-sectional study was to investigate the relation between HDL2-C and HDL3-C fractions and carotid intima-media thickness (cIMT) in the population-based Northern Manhattan Study. Methods: We evaluated 988 stroke-free participants (mean age 66±8 years; 60% women; 66% Hispanic, and 34% Non-Hispanic) with available data on HDL-C subfractions using precipitation method and cIMT assessed by a high-resolution carotid ultrasound. The associations between HDL-C subfractions and cIMT were analyzed by multiple linear regression models. Results: The mean HDL2-C was 14 ± 8 mg/dl, HDL3-C 32 ± 8 mg/dl, and the mean total HDL-C was 46 ±14 mg/dl. The mean cIMT was 0.90 ± 0.08 mm. After controlling for demographics and vascular risk factors, HDL2-C and total HDL-C were inversely associated with cIMT (per 2SDs, beta= -0.012, p=0.03 and beta= -0.012, p=0.04, respectively). The same inverse association was more pronounced among those with diabetes (per 2SDs, HDL2-C: beta= -0.036, p=0.04; HDL-C: beta= -0.032, p=0.04). HDL3-C was inversely associated with cIMT but the association was not significant (per 2SDs, beta= -0.008, p=0.13) after adjustment. Conclusions: HDL2-C had greater effect on cIMT then HDL3-C in this urban population. This effect was especially pronounced among individuals with diabetes. More research in needed to determine anti-atherosclerotic effects of HDL-C subfractions and clinical relevance of raising their levels.

The effect of menopause and gender on lipids and HDL cholesterol subfractions in apparently healthy pre- and postmenopausal women and men

analysis revealed a marked decrease of apolipoprotein B100 and an increase of apolipoprotein M in plasma of H2 group. Finally H2 treatment resulted in significant reductions in levels of several inflammatory and oxidative stress indicators in whole plasma and HDL particles. Conclusions: Hydrogen activates ATP-binding cassette transporter A1-dependent efflux, enhances HDL anti-atherosclerotic functions, and has beneficial lipid-lowering effects. The present finding may highlight the potential role of hydrogen in the regression of hypercholesterolemia and atherosclerosis.

Reference ranges of cholesterol sub-fractions in random healthy adults in Ouagadougou, Burkina Faso.

In Burkina Faso, the values that serve as clinical chemistry reference ranges are those provided by European manufacturers’ insert sheets based on reference of the Western population. However, studies conducted so far in some African countries reported significant differences in normal laboratory ranges compared with those of the industrialized world. The aim of this study was to determine reference values of cholesterol fractions in apparently normal adults in Burkina Faso that could be used to better assess the risks related to cardiovascular diseases. Study population was 279 healthy subjects aged from 15 to 50 years including 139 men and 140 women recruited at the Regional Center of Blood Transfusion of Ouagadougou, capital city of Burkina Faso (West Africa). Exclusion criteria based on history and clinical examination were used for defining reference individuals. The dual-step precipitation of HDL cholesterol sub-fractions using dextran sulfate was performed according to the procedure described by Hirano. The medians were calculated and reference values were determined at 2.5th and 97.5th percentiles. The median and upper ranges for total cholesterol, LDL cholesterol, total HDL cholesterol and HDL2 cholesterol were observed to be higher in women in comparison to men (p <0.05). These reference ranges were similar to those derived from other African countries but lower than those recorded in France and in USA. This underscores the need for such comprehensible establishment of reference values for limited resources countries. Our study provides the first cholesterol sub-fractions (HDL2 and HDL3) reference ranges for interpretation of laboratory results for cardiovascular risk management in Burkina Faso.

P24 - Paraoxonase 1 and HDL subfractions in hypercholesterolemic children and adolescents

BackgroundAssessment of the cardiovascular disease (CVD) risk factors in children can predict clinical manifestations of atherosclerosis in adulthood. The arylesterase (PON1-A) and lactonase (PON1-L) activities of paraoxonase 1 (PON1) and lipid parameters (Total cholesterol (TCH), VLDL-cholesterol (VLDL), triacylglycerols (TAG), HDL-cholesterol (HDL), LDL-cholesterol (LDL) and LDL- and HDL-subfractions and their mutual associations in 27 hypercholesterolemic children and adolescents were investigated. Methods: Serum levels of TCH and TAG were determined using a Hitachi 911 analyser (Roche Diagnostics, Switzerland). LDL- and HDL-subfractions were determined by Lipoprint® system (Quantimetrix, Corp., USA). PON1-A and PON1-L activities were determined according to Gan et al. (1991) and Aviram and Rosenblat (2008). Results: PON1-A activity was higher compared to healthy children (134.1±26.2 vs. 118.16±7.05 U/ml) and PON1-L was not different from healthy controls. Increased levels of atherogenic risk factors TCH, VLDL, IDL1 subfraction and decreased levels of the antiatherogenic IDL3 and LDL1 subfractions were observed in the hypercholesterolemic children compared to reference values. Increased levels of large HDL subfractions, comparable levels of intermediate HDL and lower levels of small HDL subfractions were observed in hypercholesterolemic children compared to healthy adults (in absence of data available for healthy children). No significant correlation between PON1-A and HDL subfractions was found. PON1-L activity positively correlated with antiatherogenic large HDL1 subfraction and negatively correlated with intermediate HDL4, 5 and 6 subfractions. ConclusionsThe findings suggest that the PON1-L activity rather than PON1-A activity play a protective role in atherosclerosis. We confirmed atheroprotective effect of large and atherogenic properties of small HDL subfractions. The intermediate HDL subfractions probably play no atheroprotective role.

Decreased APOE-containing HDL subfractions and cholesterol efflux capacity of serum in mice lacking Pcsk9

BackgroundStudies in animals showed that PCSK9 is involved in HDL metabolism. We investigated the molecular mechanism by which PCSK9 regulates HDL cholesterol concentration and also whether Pcsk9 inactivation might affect cholesterol efflux capacity of serum and atherosclerotic fatty streak volume.MethodsMass spectrometry and western blot were used to analyze the level of apolipoprotein E (APOE) and A1 (APOA1). A mouse model overexpressing human LDLR was used to test the effect of high levels of liver LDLR on the concentration of HDL cholesterol and APOE-containing HDL subfractions. Pcsk9 knockout males lacking LDLR and APOE were used to test whether LDLR and APOE are necessary for PCSK9-mediated HDL cholesterol regulation. We also investigated the effects of Pcsk9 inactivation on cholesterol efflux capacity of serum using THP-1 and J774.A1 macrophage foam cells and atherosclerotic fatty streak volume in the aortic sinus of Pcsk9 knockout males fed an atherogenic diet.ResultsAPOE and APOA1 were reduced in the same HDL subfractions of Pcsk9 knockout and human LDLR transgenic male mice. In Pcsk9/Ldlr double-knockout mice, HDL cholesterol concentration was lower than in Ldlr knockout mice and higher than in wild-type controls. In Pcsk9/Apoe double-knockout mice, HDL cholesterol concentration was similar to that of Apoe knockout males. In Pcsk9 knockout males, THP-1 macrophage cholesterol efflux capacity of serum was reduced and the fatty streak lesion volume was similar to wild-type controls.ConclusionsIn mice, LDLR and APOE are important factors for PCSK9-mediated HDL regulation. Our data suggest that, although LDLR plays a major role in PCSK9-mediated regulation of HDL cholesterol concentration, it is not the only mechanism and that, regardless of mechanism, APOE is essential. Pcsk9 inactivation decreases the HDL cholesterol concentration and cholesterol efflux capacity in serum, but does not increase atherosclerotic fatty streak volume.

HDL Cholesterol Subfractions and the Effect of Testosterone Replacement in Hypogonadism

Metabolic disorders and cardiovascular events are increased in hypogonadism. Serum HDL composition is a better cardiovascular predictor than the HDL counts. However, there is no information about the HDL subfractions in patients with hypogonadism. We designed a prospective study to investigate the HDL subfractions in treatment naïve subjects with hypogonadism and the effects of 2 different testosterone replacement regimens on the HDL subfractions. Seventy young male patients with congenital hypogonadotropic hypogonadism (CHH) and 70 age and BMI-matched healthy males were enrolled in the present study. The patients were assigned to receive intramuscular injections of testosterone esters 250 mg every 3 weeks and transdermal testosterone applications 50 mg daily. Biochemical investigations including HDL subfractions and insulin resistance were done. Patients with CHH had higher levels of insulin, HOMA-IR, WC, triglyceride, and diastolic blood pressure. Although, the HDL cholesterol concentrations were similar in both groups, hypogonadal patients had lower HDL2 and higher HDL3 levels. The total testosterone levels were independent determinants of the HDL2 subfractions. During the follow-up, a significant increase in the BMI and WC values and a significant decrease in the levels of total cholesterol, HDL cholesterol, and HDL3 were observed. No difference was present between the 2 treatment arms. These results show that patients with hypogonadism have unfavorable HDL compositions in addition to the other dysmetabolic features. However, testosterone replacement for about six months neither improves the metabolic problems nor the HDL composition. Mechanistic studies are warranted to better understand the cardiovascular effects of unfavorable HDL compositions in hypogonadism.

HDL cholesterol subfractions and the effect of testosterone replacement in hypogonadism

Metabolic disorders and cardiovascular events are increased in hypogonadism. Serum HDL composition is a better cardiovascular predictor than the HDL counts. However, there is no information about the HDL subfractions in patients with hypogonadism. We designed a prospective study to investigate the HDL subfractions in treatment naive subjects with hypogonadism and the effects of 2 different testosterone replacement regimens on the HDL subfractions. Seventy young male patients with congenital hypogonadotropic hypogonadism (CHH) and 70 age and BMI-matched healthy males were enrolled in the present study. The patients were assigned to receive intramuscular injections of testosterone esters 250 mg every 3 weeks and transdermal testosterone applications 50 mg daily. Biochemical investigations including HDL subfractions and insulin resistance were done. Patients with CHH had higher levels of insulin, HOMA-IR, WC, triglyceride, and diastolic blood pressure. Although, the HDL cholesterol concentrations were similar in both groups, hypogonadal patients had lower HDL2 and higher HDL3 levels. The total testosterone levels were independent determinants of the HDL2 subfractions. During the follow-up, a significant increase in the BMI and WC values and a significant decrease in the levels of total cholesterol, HDL cholesterol, and HDL3 were observed. No difference was present between the 2 treatment arms. These results show that patients with hypogonadism have unfavorable HDL compositions in addition to the other dysmetabolic features. However, testosterone replacement for about six months neither improves the metabolic problems nor the HDL composition. Mechanistic studies are warranted to better understand the cardiovascular effects of unfavorable HDL compositions in hypogonadism.