Dysfunctional high-density lipoprotein

Relevance of Lipoprotein Composition in Endothelial Dysfunction and the Development of Hypertension

Endothelial dysfunction and chronic inflammation are determining factors in the development and progression of chronic degenerative diseases, such as hypertension and atherosclerosis. Among the shared pathophysiological characteristics of these two diseases is a metabolic disorder of lipids and lipoproteins. Therefore, the contents and quality of the lipids and proteins of lipoproteins become the targets of therapeutic objective. One of the stages of lipoprotein formation occurs through the incorporation of dietary lipids by enterocytes into the chylomicrons. Consequently, the composition, structure, and especially the properties of lipoproteins could be modified through the intake of bioactive compounds. The objective of this review is to describe the roles of the different lipid and protein components of lipoproteins and their receptors in endothelial dysfunction and the development of hypertension. In addition, we review the use of some non-pharmacological treatments that could improve endothelial function and/or prevent endothelial damage. The reviewed information contributes to the understanding of lipoproteins as vehicles of regulatory factors involved in the modulation of inflammatory and hemostatic processes, the attenuation of oxidative stress, and the neutralization of toxins, rather than only cholesterol and phospholipid transporters. For this review, a bibliographic search was carried out in different online metabases.

Myeloperoxidase to high-density lipoprotein ratio: Potential predictor of severity and outcome in patients with acute ischemic stroke

OBJECTIVE

As a new marker of inflammation and lipid metabolism, the ratio of myeloperoxidase to high density lipoprotein (MPO/HDL) has been reported in the field of cardiovascular disease. However, the effect of MPO/HDL on acute ischemic stroke (AIS) is not clear. The purpose of this study was to explore the prognostic value of MPO/HDL level in patients with AIS.

METHODS

This study conducted a retrospective analysis of 363 patients diagnosed with AIS. Stroke severity was assessed by National Institutes of Health Stroke Scale (NIHSS). The short-term functional outcome was evaluated with modified Rankin Scale (mRS) 90 days after admission. Spearman correlation analysis was used to evaluate the correlation between MPO/HDL and NIHSS scores. The predictive value of MPO, HDL and MPO/HDL to AIS was evaluated by receiver operating characteristic curve (ROC).

RESULTS

The level of MPO/HDL in patients with NIHSS score ≥ 4 was significantly higher than that in patients with NIHSS score < 4 (P < 0.001). MPO and MPO/HDL were positively correlated with NIHSS score (P < 0.001), while HDL was negatively correlated with NIHSS score (P < 0.001). During 90-day follow-up, multivariate Logistic regression analysis showed that increased MPO/HDL levels were associated with 90-day functional outcomes. ROC showed that compared with MPO and HDL, MPO/HDL had the highest predictive value for 90-day functional prognosis in patients with AIS (AUC = 0.9825).

CONCLUSION

The level of serum MPO/HDL may be potential prognostic biomarker in AIS 90 days.

The Association Between Lipid Profile and Subfoveal Choroidal Thickness in Chinese Patients with Proliferative Diabetic Retinopathy Secondary to Type 2 Diabetes

Introduction

Extensive studies have studied the factors associated with subfoveal choroidal thickness (SFCT). However, studies of the association between lipid profile and SFCT in patients with proliferative diabetic retinopathy (PDR) in type 2 diabetes remain limited. Thus, we aimed to investigate the relationship between lipid profile and SFCT in patients with PDR.

Materials and Methods

This was a retrospective cross-sectional study. The included participants were inpatients who underwent vitrectomy for PDR with type 2 diabetes and contralateral eyes of PDR patients meeting the criteria. Multivariate linear regression analysis was used to determine the independent association between lipid profile and SFCT.

Results

A total of 131 participants with PDR were enrolled in the final analysis. The average age of the participants was 55.76 ± 9.88 years, and the average SFCT was 276.10 ± 92.92 μm. Multivariate linear regression model results showed that in the fully adjusted model, total cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) had a negative association with SFCT (β = -16.51, 95% CI: -29.57, -3.46; P = 0.0148; β = -42.65, 95% CI: -82.60, -2.70; P = 0.0390; β = -17.89, 95% CI: -33.24, -2.54; P = 0.0245, respectively), while triglyceride was not significantly associated with SFCT (β = 5.23, 95% CI: -18.57, 29.02; P = 0.6678). Furthermore, the results of stratified analysis showed that except for triglyceride, the trends of total cholesterol, HDL-C, LDL-C, and SFCT were consistent among different stratifications in participants.

Conclusion

The cholesterol profile had a significant negative association with SFCT in Chinese PDR patients, but triglyceride was not significantly associated with SFCT. This suggests that these systemic imbalances contribute to choroidal changes, and often coexist in diabetic patients.

Impact of Long-Term Cyclamate and Saccharin Consumption on Biochemical Parameters in Healthy Individuals and Type 2 Diabetes Mellitus Patients

Background: Previous studies on saccharin and cyclamate were either limited to experimental animals or lacked evaluation of their long-term consumption effects in humans. Objectives: This study evaluated the effect of chronic consumption of saccharin and cyclamate on biochemical parameters in healthy individuals and patients with type 2 diabetes mellitus. Material and Methods: Healthy and diabetic individuals were classified into two groups based on whether they consumed sweeteners or not. The participants were classified according to the amount of sweetener consumed per day and duration of consumption. Serum catalase activity, peroxynitrite, ceruloplasmin, and malondialdehyde concentrations were determined. Glycated hemoglobin, fasting glucose, creatinine, alanine transaminase, and lipid profile were also evaluated. The results suggest that saccharin and cyclamate increased HbA1C (+11.16%), MDA (+52.38%), TG (+16.74%), LDL (+13.39%), and TC/HDL (+13.11%) in healthy volunteers. Diabetic patients consuming sweeteners showed increased FSG (+17.51%), ceruloplasmin (+13.17%), and MDA (+8.92%). Diabetic patients showed a positive correlation between the number of tablets consumed per day with FSG and serum creatinine. A positive correlation was found between the duration of sweetener consumption and FSG as well as TG. Conclusion: Consumption of saccharin and cyclamate affected biochemical parameters related to metabolic functions in a time and dose-dependent manner and appear to increase oxidative stress in healthy and diabetic type 2 patients.

What adverse health effects will environmental heavy metal co-exposure bring us: based on a biological monitoring study of sanitation workers

To investigate the relationship between health effect profile and co-exposure to heavy metal, 254 sanitation workers from Guangzhou, China, were recruited. Ten urinary metals were determined by inductively coupled plasma mass spectrometry. Parameters of physical examination, including blood lipid metabolism, renal function, blood pressure, and lung function, were tested for each participant. The hazard quotients (HQs) of eight heavy metals were evaluated. Cobalt, copper (Cu), molybdenum (Mo), nickel (Ni), and tin (Sn) demonstrated the top five associations with human health with the ∑₁₉β as 2.220, 1.351, 1.234, 0.957, and 0.930, respectively. Most physical examination parameters of workers were under the normal ranges, except the levels of forced mid expiratory flow rate (MMEF_75/25), the maximum expiratory flow rate at 25% vital capacity (MEF₂₅) and apolipoprotein B in the first quartile, and the level of uric acid in the third quartile of sanitation works. Moreover, Cu was significantly associated with diastolic pressure, pulse, and high density lipid (p < 0.05). Each unit increase in Mo level was related to a 120% increase odd ratio (OR) of abnormal of systolic pressure, but was significantly and negatively correlated with high density lipoprotein and apolipoprotein A, suggesting that Mo exposure may be a risk factor of cardiovascular disease. Each unit increase in Ni and Sn levels was associated with an increased OR of abnormal rate of MMEF_75/25 and MEF₂₅ (p < 0.001), suggesting the increasing risks of respiratory diseases. Sanitation workers exposed to Ni and Pb alone had no carcinogenic risks (HQ < 1). However, 23.8%, 34.6%, and 87.3% of sanitation workers confronted non-carcinogenic risks when exposed to Cu, Mo alone (HQ > 1), or co-exposed to the four heavy metals (HI > 1). Our study preliminarily revealed the potential sensitive health indicators of heavy metal co-exposure, which will provide beneficial health protection suggestions for the occupational populations.

Predictive Value of Second-Trimester Maternal Lipid Profiling in Early-Onset Pre-eclampsia: A Prospective Cohort Study and Nomogram

Purpose: Maternal lipid profile in second trimester has rarely been investigated in the risk assessment for pre-eclampsia (PE). Since early-onset PE often companied by much worse clinical outcomes, thus, we aimed to evaluate the predictive value of second-trimester maternal lipid profiling for early-onset PE. Methods: A prospective cohort study was conducted to measure the second-trimester maternal lipid profile of pregnant women from January to December 2019. The pairwise association between maternal lipid profile and PE onset or pregnancy termination time was quantified. Multiple logistic regression was preformed to define risk factors for early-onset PE, and a nomogram for early-onset PE was developed. The net benefit of our model was evaluated by calibration curve and decision curve analyses. Results: We enrolled 5,908 pregnant women and they were divided into healthy (n = 5,789), late-onset PE (n = 64), and early-onset PE (n = 55) groups. Total cholesterol (TC), triglycerides (TG), and low-density lipoprotein cholesterol (LDL-c) were elevated in patients with PE, while high-density lipoprotein cholesterol (HDL-c) was decreased in patients with PE. TC, TG, and LDL-c were negatively correlated with PE onset time or gestational week at delivery. Receiver operating characteristic curves (ROC) defined the cutoff values of TG and HDL-c, and the final regression model included five statistically significant risk predictors for early-onset PE (maternal age of ≥35 years, multipara, pre-pregnancy body mass index (BMI) ≥25 kg/m², second trimester TG ≥ 2.59 mmol/L and second trimester HDL-c ≤ 2.03 mmol/L. The nomogram had an excellent diagnostic performance (area under the curve = 0.912, sensitivity = 92.7%, and specificity = 76%) and was further validated with good calibration and positive net benefits in a decision curve analysis. Conclusions: An abnormally increased TG concentration and a decreased HDL-c concentration might serve as predictors of early-onset PE. Whether blood lipid-lowering measures can improve severe PE prognosis require further clarification.

Association between extremely high high-density lipoprotein-cholesterol and hypertensive retinopathy: results of a cross-sectional study from Kanagawa Investigation of Total Checkup Data from the National Database-6 (KITCHEN-6)

OBJECTIVES

Doubt has been cast on the atheroprotective effect of very high high-density lipoprotein cholesterol (HDL-C). Hypertensive retinopathy (HR) is caused by persistent systemic hypertension. Therefore, we aimed to investigate the association between extremely high HDL-C (EH-HDL) and HR.

DESIGN

A cross-sectional study.

PARTICIPANTS

A total of 4072 general Japanese population aged 40-74 years who underwent regular medical check-ups including fundus examinations.

OUTCOME MEASURES

HR and clinical parameters including serum HDL-C were investigated. HR was determined by the Keith-Wagener classification and the Scheie classifications for Hypertension and Atherosclerosis (n=4054 available). Serum HDL-C was divided into five categories: 30-49, 50-69, 70-89, 90-109 and ≥110 mg/dL.

RESULTS

Overall, 828 (20.3%) subjects had Keith-Wagener-HR, 578 (14.3%) had hypertension-HR, and 628 (15.5%) had atherosclerosis-HR. Blood pressure decreased as HDL-C level increased, whereas the prevalences of HRs showed U-shaped curves against HDL-C with minimum values for HDL-C 90-109 mg/dL. In logistic regression analyses, EH-HDL ≥110 mg/dL was significantly associated with Keith-Wagener-HR and atherosclerosis-HR, compared with HDL-C 90-109 mg/dL after adjustments for age, sex and systolic blood pressure (OR 3.01, 95% CI 1.45 to 6.27 and OR 2.23, 95% CI 1.03 to 4.86). The hypertension-HR was not significantly associated with EH-HDL regardless of adjustment for the confounding factors (p=0.05-0.08). Although serum HDL-C as a continuous variable was inversely associated with three HRs, which disappeared after adjustment for the confounding factors.

CONCLUSION

EH-HDL may be associated with HR independently of blood pressure, suggesting that EH-HDL reflects a special atherosclerotic condition.

Biomarkers of lipid metabolism in patients with juvenile idiopathic arthritis: relationship with disease subtype and inflammatory activity

BACKGROUND

To describe the biomarkers of lipid metabolism in children and adolescents with polyarticular and systemic JIA and to relate them to diseases subtypes, diseases activity markers, and nutritional status.

METHODS

A cross-sectional study including 62 JIA patients was performed. The following variables were evaluated: disease activity and medications used, body mass index, height for age (z-score), skin folds (bicipital, tricipital, subscapular and suprailiac), food intake based on three 24-h food recalls, lipid profile (total cholesterol (CT), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides (TG) and non-HDL (N-HDLc), glycemia and insulin, erythrocyte sedimentation rate (ESR), ultrasensitive C-reactive protein (us-CRP) and apolipoproteins A-I and B (Apo A-I and Apo B).

RESULTS

Dyslipidemia was observed in 83.3% of the patients. Based on classical lipid profile, low HDL-c levels was the most frequently alteration observed. Inadequate levels of LDL-c, Apo B and NHDL-c were significantly more frequent in the systemic JIA subtype when compared to the polyarticular subtype (p = 0.017, 0.001 and 0.042 respectively). Patients on biological therapy had a better adequacy of Apo A-I concentrations. The ESR showed a negative correlation with Apo A-I level (r = - 0.25, p = 0.047).

CONCLUSION

We concluded that dyslipidemia is common in patients with JIA, especially in systemic subtype. The systemic subtype and an elevated ESR were associated with lower concentrations of Apo A-I, suggesting the participation of the inflammatory process.

Myeloperoxidase As a Multifaceted Target for Cardiovascular Protection

Significance: Myeloperoxidase (MPO) is a heme peroxidase that is primarily expressed by neutrophils. It has the capacity to generate several reactive species, essential for its inherent antimicrobial activity and innate host defense. Dysregulated MPO release, however, can lead to tissue damage, as seen in several diseases. Increased MPO levels in circulation are therefore widely associated with conditions of increased oxidative stress and inflammation. Recent Advances: Several studies have shown a strong correlation between MPO and cardiovascular disease (CVD), through which elevated levels of circulating MPO are linked to poor prognosis with increased risk of CVD-related mortality. Accordingly, circulating MPO is considered a "high-risk" biomarker for patients with acute coronary syndrome, atherosclerosis, heart failure, hypertension, and stroke, thereby implicating MPO as a multifaceted target for cardiovascular protection. Consistently, recent studies that target MPO in animal models of CVD have demonstrated favorable outcomes with regard to disease progression. Critical Issues: Although most of these studies have established a critical link between circulating MPO and worsening cardiac outcomes, the mechanisms by which MPO exerts its detrimental effects in CVD remain unclear. Future Directions: Elucidating the mechanisms by which elevated MPO leads to poor prognosis and, conversely, investigating the beneficial effects of therapeutic MPO inhibition on alleviating disease phenotype will facilitate future MPO-targeted clinical trials for improving CVD-related outcomes.

Anti-Atherosclerotic Activity of (3R)-5-Hydroxymellein from an Endophytic Fungus Neofusicoccum parvum JS-0968 Derived from Vitex rotundifolia through the Inhibition of Lipoproteins Oxidation and Foam Cell Formation

An endophytic fungus, Neofusicoccum parvum JS-0968, was isolated from a plant, Vitex rotundifolia. The chemical investigation of its cultures led to the isolation of a secondary metabolite, (3R)-5-hydroxymellein. It has been reported to have antifungal, antibacterial, and antioxidant activity, but there have been no previous reports on the effects of (3R)-5-hydroxymellein on atherosclerosis. The oxidation of lipoproteins and foam cell formation have been known to be significant in the development of atherosclerosis. Therefore, we investigated the inhibitory effects of (3R)-5-hydroxymellein on atherosclerosis through low-density lipoprotein (LDL) and high-density lipoprotein (HDL) oxidation and macrophage foam cell formation. LDL and HDL oxidation were determined by measuring the production of conjugated dienes and malondialdehyde, the amount of hyperchromicity and carbonyl content, conformational changes, and anti-LDL oxidation. In addition, the inhibition of foam cell formation was measured by Oil red O staining. As a result, (3R)-5-hydroxymellein suppressed the oxidation of LDL and HDL through the inhibition of lipid peroxidation, the decrease of negative charges, the reduction of hyperchromicity and carbonyl contents, and the prevention of apolipoprotein A-I (ApoA-I) aggregation and apoB-100 fragmentation. Furthermore, (3R)-5-hydroxymellein significantly reduced foam cell formation induced by oxidized LDL (oxLDL). Taken together, our data show that (3R)-5-hydroxymellein could be a potential preventive agent for atherosclerosis via obvious anti-LDL and HDL oxidation and the inhibition of foam cell formation.

Anti-Atherosclerotic Effects of Fruits of Vitex rotundifolia and Their Isolated Compounds via Inhibition of Human LDL and HDL Oxidation

Low-density lipoprotein (LDL) and high-density lipoprotein (HDL) oxidation are well known to increase the risk for atherosclerosis. In our ongoing research on natural products with inhibitory activities against oxidation of lipoproteins, fruits of Vitex rotundifolia were found to be highly active. There is no report on the effects on LDL and HDL oxidation. Herein, we investigated the inhibitory effects of V. rotundifolia fruit extract and its six compounds, which are: (1) artemetin, (2) casticin, (3) hesperidin, (4) luteolin, (5) vitexin, and (6) vanillic acid, against LDL and HDL oxidation. The LDL and HDL oxidations were determined by measuring production of conjugated dienes and thiobarbituric acid reactive substances, amount of hyperchromicity and carbonyl content, change in electrical charge, and apoA-I aggregation. In addition, the contents of the compounds in the extracts were analyzed using HPLC-DAD. Consequently, extracts of Vitex rotundifolia fruits and compounds 2 and 4 suppressed oxidation of LDL and HDL, showing inhibition of lipid peroxidation, decrease of negative charges in lipoproteins, reduction of hyperchromicity, decrease in carbonyl contents, and prevention of apoA-I aggregation. In particular, compounds 2 and 4 exhibited more potent inhibitory effect on oxidation of LDL and HDL than the extracts, suggesting their protective role against atherosclerosis via inhibition of LDL and HDL oxidation. The contents of artemetin, casticin, and vanillic acid in the extracts were 1.838 ± 0.007, 8.629 ± 0.078, and 1.717 ± 0.006 mg/g, respectively.

Epimedium koreanum Extract and Its Flavonoids Reduced Atherosclerotic Risk via Suppressing Modification of Human HDL

Atherosclerosis is the key factor responsible for cardiovascular events, which is a major cause of morbidities and mortalities worldwide. It is well known that high-density lipoprotein (HDL) oxidation and glycation increases the risk for atherosclerosis. Epimedium koreanum has been used as a traditional oriental medicine for treating erectile dysfunction, kidney diseases, osteoporosis, and breast cancer. However, no reports on the effects of E. koreanum on HDL modification exist. In this study, we investigated the inhibitory effects of E. koreanum extract and its eight flavonoids, which are: (1) anhydroicaritin 3-O-rhamnoside, (2) β-anhydroicaritin, (3–5) epimedins A-C, (6) epimedoside A, (7) icariin, and (8) des-O-methyl-β-anhydroicaritin, against HDL modification. HDLs obtained from pooled human plasma samples were incubated in vitro with E. koreanum extract or each compound in the presence of copper sulfate or fructose. The HDL modifications were evaluated by measuring generation of conjugated dienes, production of thiobarbituric acid reactive substances, change in electrophoretic mobility of apoA-I, advanced glycation end products formation, and apoA-I aggregation. Consequently, E. koreanum extract and compound 8 suppressed HDL modification through inhibition of lipid peroxidation, apoA-I aggregation, negative charge increase, and AGEs formation. In particular, compound 8 showed more potent inhibitory effect on HDL modification than the extracts, suggesting its protective role against atherosclerosis via inhibition of HDL oxidation and glycation.

[Antidiabetic role of high density lipoproteins]

Disturbance in lipid metabolism can be both a cause and a consequence of the development of diabetes mellitus (DM). One of the most informative indicator of lipid metabolism is the ratio of atherogenic and antiatherogenic fractions of lipoproteins and their protein components. The review summarizes literature data and own results indicating the important role of high-density lipoprotein (HDL) and their main protein component, apolipoprotein A-I (apoA-I), in the pathogenesis of type 2 DM. On the one hand, HDL are involved in the regulation of insulin secretion by b-cells and insulin-independent absorption of glucose. On the other hand, insulin resistance and hyperglycemia lead to a decrease in HDL levels and cause modification of their protein component. In addition, HDL, possessing anti-inflammatory and mitogenic properties, provide anti-diabetic protection through systemic mechanisms. Thus, maintaining a high concentration of HDL and apoA-I in blood plasma and preventing their modification are important issues in the context of prevention and treatment of diabetes.

Myeloperoxidase - A bridge linking inflammation and oxidative stress with cardiovascular disease

Myeloperoxidase (MPO) is a member of the superfamily of heme peroxidases that is mainly expressed in neutrophils and monocytes. MPO-derived reactive species play a key role in neutrophil antimicrobial activity and human defense against various pathogens primarily by participating in phagocytosis. Elevated MPO levels in circulation are associated with inflammation and increased oxidative stress. Multiple lines of evidence suggest an association between MPO and cardiovascular disease (CVD) including coronary artery disease, congestive heart failure, arterial hypertension, pulmonary arterial hypertension, peripheral arterial disease, myocardial ischemia/reperfusion-related injury, stroke, cardiac arrhythmia and venous thrombosis. Elevated MPO levels are associated with a poor prognosis including increased risk for overall and CVD-related mortality. Elevated MPO may signify an increased risk for CVD for at least 2 reasons. First, low-grade inflammation and increased oxidative stress coexist with many metabolic abnormalities and comorbidities and consequently an elevated MPO level may represent an increased cardiometabolic risk in general. Second, MPO produces a large number of highly reactive species which can attack, destroy or modify the function of every known cellular component. The most common MPO actions relevant to CVD are generation of dysfunctional lipoproteins with an increased atherogenicity potential, reduced NO availability, endothelial dysfunction, impaired vasoreactivity and atherosclerotic plaque instability. These actions strongly suggest that MPO is directly involved in the pathophysiology of CVD. In this regard MPO may be seen as a mediator or an instrument through which inflammation promotes CVD at molecular and cellular level. Clinical value of MPO therapeutic inhibition remains to be tested.

Myeloperoxidase mediated HDL oxidation and HDL proteome changes do not contribute to dysfunctional HDL in Chinese subjects with coronary artery disease

High density lipoprotein (HDL) cholesterol levels and cholesterol efflux capacity (CEC) are inversely correlated with coronary artery disease (CAD) risk. Myeloperoxidase (MPO) derived oxidants and HDL proteome changes are implicated in HDL dysfunction in subjects with CAD in the United States; however, the effect of MPO on HDL function and HDL proteome in ethnic Chinese population is unknown. We recruited four matched ethnic Chinese groups (20 patients each): subjects with 1) low HDL levels (HDL levels in men <40mg/dL and women <50mg/dL) and non-CAD (identified by coronary angiography or cardiac CT angiography); 2) low HDL and CAD; 3) high HDL (men >50mg/dL; women >60mg/dL) with no CAD; and 4) high HDL with CAD. Serum cytokines, serum MPO levels, serum CEC, MPO-oxidized HDL tyrosine moieties, and HDL proteome were assessed by mass spectrometry individually in the four groups.

The cytokines, MPO levels, and HDL proteome profiles were not significantly different between the four groups. As expected, CEC was depressed in the entire CAD group but more specifically in the CAD low-HDL group. HDL of CAD subjects had significantly higher 3-nitrotyrosine than non-CAD subjects, but the MPO-specific 3-chlorotyrosine was unchanged; CEC in the CAD low-HDL group did not correlate with either HDL 3-chlorotyrosine or 3-nitrotyrosine levels. Neither 3-chlorotyrosine, which is MPO-specific, nor 3-nitrotyrosine generated from MPO or other reactive nitrogen species was associated with CEC. MPO mediated oxidative stress and HDL proteome composition changes are not the primary cause HDL dysfunction in Chinese subjects with CAD. These studies highlight ethnic differences in HDL dysfunction between United States and Chinese cohorts raising possibility of unique pathways of HDL dysfunction in this cohort.

High Consumption of Iron Exacerbates Hyperlipidemia, Atherosclerosis, and Female Sterility in Zebrafish via Acceleration of Glycation and Degradation of Serum Lipoproteins

Elevated serum iron level is linked with an increased risk of diabetes and atherosclerosis. However, the pathological mechanism by which iron affects serum lipoprotein levels is unknown. To elucidate the mechanism, a high dose of ferrous ion was applied (final 60 µM, 120 µM) to human serum lipoproteins, macrophages, and human dermal fibroblast (HDF) cells. Iron-treated lipoproteins showed loss of antioxidant ability along with protein degradation and multimerization, especially co-treatment with fructose (final 10 mM). In the presence of fructose, HDF cells showed 3.5-fold more severe cellular senescence, as compared to the control, dependent on the dosage of fructose. In macrophages, phagocytosis of acetylated low-density lipoprotein (acLDL) was more accelerated by ferrous ion, occurring at a rate that was up to 1.8-fold higher, than acLDL alone. After 24 weeks supplementation with 0.05% and 0.1% ferrous ion in the diet (wt/wt), serum total cholesterol (TC) level was elevated 3.7- and 2.1-fold, respectively, under normal diet (ND). Serum triglyceride (TG) was elevated 1.4- and 1.7-fold, respectively, under ND upon 0.05% and 0.1% ferrous ion supplementation. Serum glucose level was elevated 2.4- and 1.2-fold under ND and high cholesterol diet (HCD), respectively. However, body weight was decreased by the Fe²⁺ consumption. Iron consumption caused severe reduction of embryo laying and reproduction ability, especially in female zebrafish via impairment of follicular development. In conclusion, ferrous ion treatment caused more pro-atherogenic, and pro-senescence processes in human macrophages and dermal cells. High consumption of iron exacerbated hyperlipidemia and hyperglycemia as well as induced fatty liver changes and sterility along with reduction of female fertility.

High-dose consumption of NaCl resulted in severe degradation of lipoproteins associated with hyperlipidemia, hyperglycemia, and infertility via impairment of testicular spermatogenesis

Although the effect of NaCl on serum lipid levels and hypertension is well known, the detailed mechanism of lipoprotein metabolism still remains unclear. To study the physiological effects of high salt consumption on lipoprotein metabolism, NaCl was administered to human cells and zebrafish. Wildtype zebrafish (10-week old) were fed 10% NaCl (wt/wt) in tetrabit diet with or without 4% cholesterol (wt/wt) for 21 weeks. Treatment with NaCl accelerated oxidation and glycation of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) as well as induced proteolytic degradation and aggregation. NaCl treatment also exacerbated phagocytosis of oxLDL into macrophage as well as cytotoxicity. The consumption of high salt diet (HSD, final 5% or 10% in diet, wt/wt) supplemented with or without 4% cholesterol for 21 weeks resulted in a remarkable elevation of serum cholesterol, triglyceride, glucose, and hepatic inflammation levels in zebrafish with significant weight loss. Fertility based on egg production was reduced by up to 45% in the HSD group. However, embryonic survivability after hatching was significantly lowered to less than 55%, whereas the control group showed 87% survival. The HSD group showed abnormal testicular histology as well as spermatogenic defects, especially upon the consumption of HCD. These results suggest that hyperlipidemia and high salt consumption have an additive effect on male fertility impairment. High salt consumption exacerbates hyperlipidemia, inflammation, spermatogenic defects, and infertility via a modification of lipoproteins.

Anti-atherogenic properties of high-density lipoproteins in psychiatric patients before and after two months of atypical anti-psychotic therapy

Some of the medications used for the management of schizophrenia are associated with clinically significant increases in weight and adverse alterations in serum lipid levels. The aim of the study was to investigate the effect of short-term (two months) treatment with atypical anti-psychotics on coronary heart disease risk factors, including the functional properties of high-density lipoprotein (HDL), in psychiatric patients. Nineteen patients diagnosed with schizophrenia, schizoaffective, and bipolar disorder and ten healthy volunteers were enrolled in the study. In the present study blood was drawn at baseline and after two months of atypical anti-psychotic treatment. Wilcoxon non-parametric-test was used to examine differences in the psychotic group before and two months after treatment.Waist circumference and oxidative stress in psychiatric patients were higher compared with the control group. Serum-mediated cholesterol efflux capacity was lower in psychotic patients compared to controls. Two months of anti-psychotic therapy was associated with increased abdominal obesity, decreased paraoxonase lactonase activity, but with no further change in serum-mediated cholesterol efflux from macrophages. Psychotic patients have low serum-mediated cholesterol efflux from macrophages as a parameter of HDL functionality. Atypical anti-psychotic treatment for two months increased metabolic derangements in these patients but without further decrement in serum-mediated cholesterol efflux.

Increased plasma cholesterol esterification by LCAT reduces diet-induced atherosclerosis in SR-BI knockout mice

LCAT, a plasma enzyme that esterifies cholesterol, has been proposed to play an antiatherogenic role, but animal and epidemiologic studies have yielded conflicting results. To gain insight into LCAT and the role of free cholesterol (FC) in atherosclerosis, we examined the effect of LCAT over- and underexpression in diet-induced atherosclerosis in scavenger receptor class B member I-deficient [Scarab(-/-)] mice, which have a secondary defect in cholesterol esterification. Scarab(-/-)×LCAT-null [Lcat(-/-)] mice had a decrease in HDL-cholesterol and a high plasma ratio of FC/total cholesterol (TC) (0.88 ± 0.033) and a marked increase in VLDL-cholesterol (VLDL-C) on a high-fat diet. Scarab(-/-)×LCAT-transgenic (Tg) mice had lower levels of VLDL-C and a normal plasma FC/TC ratio (0.28 ± 0.005). Plasma from Scarab(-/-)×LCAT-Tg mice also showed an increase in cholesterol esterification during in vitro cholesterol efflux, but increased esterification did not appear to affect the overall rate of cholesterol efflux or hepatic uptake of cholesterol. Scarab(-/-)×LCAT-Tg mice also displayed a 51% decrease in aortic sinus atherosclerosis compared with Scarab(-/-) mice (P < 0.05). In summary, we demonstrate that increased cholesterol esterification by LCAT is atheroprotective, most likely through its ability to increase HDL levels and decrease pro-atherogenic apoB-containing lipoprotein particles.

Measurement of retinal function with flash-electroretinography in Chinese patients with hyperlipidemia

BACKGROUND

We used flash electroretinography (F-ERG) to determine if retinal function was impaired in patients with hyperlipidemia, including visual acuity and fundus morphological changes, and to identify predictors of impaired retinal function in hyperlipidemia patients.

METHODS

This was a prospective case-control study (Shanghai, China; February 2011 to January 2012) in 696 hyperlipidemia patients and 136 healthy controls. Exclusion criteria included best-corrected visual acuity <0.6, previous intraocular surgery, and chronic comorbidities. Each participant underwent a comprehensive series of ophthalmologic examinations, and standard F-ERG examination. Data were analyzed using t-tests and multivariate analysis.

RESULTS

Six hundred and twenty-six hyperlipidemia patients (57.69 ± 14.01 years; 59.58% female) and 120 healthy controls (55.13 ± 14.03 years; 60% female) were included in the final analysis. After adjustment for age and gender using multivariate covariance analysis, F-ERG result revealed significantly lower response amplitudes in the hyperlipidemia group (P < 0.05), and longer implicit times (P < 0.05) than the control group. F-ERG parameters were significantly different between the two groups. Stepwise multiple linear regression analysis showed that serum LDL levels (P < 0.001), BMI (P < 0.001), duration of hyperlipidemia (P < 0.001), and serum HDL levels (P = 0.03) were negatively correlated with ΣOps.

CONCLUSION

The present study suggests that the retinal function of hyperlipidemia patients was significantly lower than in healthy controls, even before the occurrence of pathological changes in the fundus.

Effects of cigarette smoking on HDL quantity and function: implications for atherosclerosis

Cigarette smoking has been identified as an independent and preventable risk factor for atherosclerosis and cardiovascular disease. Population studies have shown that plasma high density lipoprotein (HDL) cholesterol levels are inversely related to the risk of developing cardiovascular disease. Cigarette smoking is associated with reduced HDL cholesterol levels. Cigarette smoking can alter the critical enzymes of lipid transport, lowering lecithin: cholesterol acyltransferase (LCAT) activity and altering cholesterol ester transfer protein (CETP) and hepatic lipase activity, which attributes to its impact on HDL metabolism and HDL subfractions distribution. In addition, HDL is susceptible to oxidative modifications by cigarette smoking, which makes HDL become dysfunctional and lose its atheroprotective properties in smokers. Therefore, cigarette smoking has a negative impact on both HDL quantity and function, which can explain, in part, the increased risk of cardiovascular disease in smokers.

Scavenger receptor BI and high-density lipoprotein regulate thymocyte apoptosis in sepsis

OBJECTIVE

Thymocyte apoptosis is a major event in sepsis; however, how this process is regulated remains poorly understood.

APPROACH AND RESULTS

Septic stress induces glucocorticoids production which triggers thymocyte apoptosis. Here, we used scavenger receptor BI (SR-BI)-null mice, which are completely deficient in inducible glucocorticoids in sepsis, to investigate the regulation of thymocyte apoptosis in sepsis. Cecal ligation and puncture induced profound thymocyte apoptosis in SR-BI(+/+) mice, but no thymocyte apoptosis in SR-BI(-/-) mice because of lack of inducible glucocorticoids. Unexpectedly, supplementation of glucocorticoids only partly restored thymocyte apoptosis in SR-BI(-/-) mice. We demonstrated that high-density lipoprotein (HDL) is a critical modulator for thymocyte apoptosis. SR-BI(+/+) HDL significantly enhanced glucocorticoid-induced thymocyte apoptosis, but SR-BI(-/-) HDL had no such activity. Further study revealed that SR-BI(+/+) HDL modulates glucocorticoid-induced thymocyte apoptosis via promoting glucocorticoid receptor translocation, but SR-BI(-/-) HDL loses such regulatory activity. To understand why SR-BI(-/-) HDL loses its regulatory activity, we analyzed HDL cholesterol contents. There was 3-fold enrichment of unesterified cholesterol in SR-BI(-/-) HDL compared with SR-BI(+/+) HDL. Normalization of unesterified cholesterol in SR-BI(-/-) HDL by probucol administration or lecithin cholesteryl acyltransferase expression restored glucocorticoid-induced thymocyte apoptosis, and incorporating unesterified cholesterol into SR-BI(+/+) HDL rendered SR-BI(+/+) HDL dysfunctional. Using lckCre-GR(fl/fl) mice in which thymocytes lack cecal ligation and puncture-induced thymocyte apoptosis, we showed that lckCre-GR(fl/fl) mice were significantly more susceptible to cecal ligation and puncture-induced septic death than GR(fl/fl) control mice, suggesting that glucocorticoid-induced thymocyte apoptosis is required for protection against sepsis.

CONCLUSIONS

The findings in this study reveal a novel regulatory mechanism of thymocyte apoptosis in sepsis by SR-BI and HDL.

15-lipoxygenase-mediated modification of HDL3 impairs eNOS activation in human endothelial cells

Caveolae are cholesterol and glycosphingolipids-enriched microdomains of plasma membranes. Caveolin-1 represents the major structural protein of caveolae, that also contain receptors and molecules involved in signal transduction pathways. Caveolae are particularly abundant in endothelial cells, where they play important physiological and pathological roles in regulating endothelial cell functions. Several molecules with relevant functions in endothelial cells are localized in caveolae, including endothelial nitric oxide synthase (eNOS), which regulates the production of nitric oxide, and scavenger receptor class B type I (SR-BI), which plays a key role in the induction of eNOS activity mediated by high density lipoproteins (HDL). HDL have several atheroprotective functions, including a positive effect on endothelial cells, as it is a potent agonist of eNOS through the interaction with SR-BI. However, the oxidative modification of HDL may impair their protective role. In the present study we evaluated the effect of 15-lipoxygenase-mediated modification of HDL3 on the expression and/or activity of some proteins localized in endothelial caveolae and involved in the nitric oxide generation pathway. We found that after modification, HDL3 failed to activate eNOS and to induce NO production, due to both a reduced ability to interact with its own receptor SR-BI and to a reduced expression of SR-BI in cells exposed to modified HDL. These findings suggest that modification of HDL may reduce its endothelial-protective role also by interfering with vasodilatory function of HDL.

Lipids and lipoproteins and risk of different vascular events in the MRC/BHF Heart Protection Study

BACKGROUND

Low-density lipoprotein (LDL) cholesterol and high-density lipoprotein (HDL) cholesterol are established risk factors for vascular disease, but lipoprotein particle concentrations may be stronger determinants of risk.

METHODS AND RESULTS

Associations between vascular events and baseline concentrations of cholesterol fractions, apolipoproteins B and A(1), and lipoprotein particles assessed by nuclear magnetic resonance were considered in the Heart Protection Study randomized trial of simvastatin versus placebo (>5000 vascular events during 5.3 years of follow-up among 20 000 participants). Major occlusive coronary events were equally strongly associated with the cholesterol- and particle-based total LDL measures; adjusted hazard ratios per 1-SD-higher level were 1.25 (95% confidence interval [CI], 1.16-1.34) for LDL cholesterol, 1.22 (95% CI, 1.14-1.32) for non-HDL cholesterol, 1.23 (95% CI, 1.15-1.33) for apolipoprotein B, and 1.25 (95% CI, 1.16-1.35) for LDL particle number. Given the total LDL particle number, the distribution between small and large particles did not add predictive value. Associations of these different LDL-related measures were similar with arterial revascularization procedures but much weaker or nonexistent with ischemic stroke and other cardiac events (mainly heart failure). After adjustment for LDL particle number, the hazard ratios for major occlusive coronary event per 1-SD-higher level were 0.91 (95% CI, 0.86-0.96) for HDL cholesterol and 0.89 (95% CI, 0.85-0.93) for HDL particle number. Other cardiac events were inversely associated with total (hazard ratio, 0.84; 95% CI, 0.79-0.90) and small (0.82; 95% CI, 0.76-0.89) HDL particle number but only very weakly associated with HDL cholesterol (0.94; 95% CI, 0.88-1.00).

CONCLUSIONS

In a population at 2% average coronary event risk per year, cholesterol, apolipoprotein, and particle measures of LDL were strongly correlated and had similar predictive values for incident major occlusive vascular events. It is unclear whether the associations between HDL particle numbers and other cardiac events represent a causal or reverse-causal effect.

Hypochlorite-induced oxidative stress elevates the capability of HDL in promoting breast cancer metastasis

Background

Previous studies suggest that oxidative stress plays an important role in the development of breast cancer. There is a significant inverse relationship between HDL and the risk and mortality of breast cancer. However, it is well known that under conditions of oxidative stress, such as breast cancer, HDL can be oxidatively modifiedand these modifications may have an effect on the functions of HDL. The purpose of this study is to determine the different effects of normal and oxidized (caused by hypochlorite-induced oxidative stress) HDL on breast cancer cell metastasis.

Methods

Human breast cancer cell lines were treated with normal and hypochlorite-oxidized HDL, and then cell metastasis potency in vivo and the abilities of migration, invasion, adhesion to HUVEC and ECM in vitro were examined. Integrin expression and PKC activity were evaluated, and PKC inhibitor and PKC siRNA was applied.

Results

We found hypochlorite-oxidized HDL dramatically promotes breast cancer cell pulmonary metastasis (133.4% increase at P < 0.0 l for MDA-MB-231 by mammary fat pad injection; 164.3% increase at P < 0.01 for MCF7 by tail vein injection) and hepatic metastasis (420% increase at P < 0.0 l for MDA-MB-231 by mammary fat pad injection; 1840% fold increase at P < 0.001 for MCF7 by tail vein injection) in nude mice, and stimulates higher cell invasion (85.1% increase at P < 0.00 l for MDA-MB-231; 88.8% increase at P < 0.00 l for MCF7;), TC-HUVEC adhesion (43.4% increase at P < 0.00 l for MDA-MB-231; 35.2% increase at P < 0.00 l for MCF7), and TC-ECM attachment (41.0% increase at P < 0.00 l for MDA-MB-231; 26.7% increase at P < 0.05 for MCF7) in vitro compared with normal HDL. The data also shows that the PKC pathway is involved in the abnormal actions of hypochlorite-oxidized HDL.

Conclusions

Our study demonstrated that HDL under hypochlorite-induced oxidative stress stimulates breast cancer cell migration, invasion, adhesion to HUVEC and ECM, thereby promoting metastasis of breast cancer. These results suggest that HDL-based treatments should be considered for treatment of breast cancer patients.

HDL of patients with type 2 diabetes mellitus elevates the capability of promoting breast cancer metastasis

PURPOSE

Epidemiologic studies suggested complicated associations between type 2 diabetes mellitus and breast cancer. High-density lipoprotein (HDL) is inversely associated with the risk and mortality of breast cancer. Our study is to determine the different effects of normal and diabetic HDL on breast cancer cell metastasis.

EXPERIMENTAL DESIGN

MDA-MB-231 and MCF7 cells were treated with N-HDL, D-HDL, G-HDL, and Ox-HDL. Cell metastasis potency was examined using a tail-vein injection model, and cell adhesion abilities to human umbilical vein endothelial cells (HUVEC) and extracellular matrix (ECM) were determined in vitro. Integrin expression and protein kinase C (PKC) activity were evaluated, and PKC inhibitor was applied.

RESULTS

D-HDL dramatically promoted cell pulmonary metastasis (103.6% increase at P < 0.001 for MDA-MB-231 with 1 × 10(5) cell injection; 157.1% increase at P < 0.05 for MCF7 with 4 × 10(5) cell injection) and hepatic metastasis (18.1-fold increase at P < 0.001 for MCF7 with 4 × 10(5) cell injection), and stimulated higher TC-HUVECs adhesion (21.9% increase at P < 0.001 for MDA-MB-231; 23.6% increase at P < 0.05 for MCF7) and TC-ECM attachment (59.9% and 47.9% increase, respectively, for MDA-MB-231 and MCF7, both at P < 0.01) compared with N-HDL. D-HDL stimulated higher integrin (β1, β2, β3, and αν) expression on cell surface and induced higher PKC activity. Increased TC-HUVECs and TC-ECM adhesion induced by D-HDL, G-HDL, and Ox-HDL could be inhibited by staurosporine.

CONCLUSIONS

Our study showed that glycation and oxidation of HDL in diabetic patients could lead to abnormal actions on breast cancer cell adhesion to HUVECs and ECM, thereby promoting metastasis progression of breast cancer. This will largely draw the attention of HDL-based treatments in the diabetes patients with breast cancer.

Lead concentrations in relation to multiple biomarkers of cardiovascular disease: the Normative Aging Study

BACKGROUND

Lead exposure has been associated with cardiovascular disease (CVD) in animal and human studies. However, the mechanisms of action have not been fully elucidated. We therefore examined the relationship between lead and multiple biomarkers of CVD.

METHODS

Participants were older men from the Normative Aging Study without preexisting coronary heart disease, diabetes, or active infection at baseline (n = 426). Serum biomarkers included lipid profile [total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides] and inflammatory markers [C-reactive protein, intercellular adhesion molecule-1, interleukin-6, and tumor necrosis factor receptor-2 (TNF-R2)]. We measured lead in blood and in bone by K-shell X-ray fluorescence. In this sample, 194 men (44.3%) had two or more repeated measures, resulting in 636 observations for analysis. We conducted analyses using mixed effects models with random subject intercepts.

RESULTS

Lead levels were associated with several CVD biomarkers, including levels of TNF-R2 and lipid markers. Specifically, in multivariable models, a 50% increase in blood lead level was associated with 26% increased odds of high TNF-R2 levels (> 5.52 ng/mL; odds ratio = 1.26; 95% confidence interval: 1.09, 1.45). There were positive associations of blood lead level with total cholesterol and HDL levels, and these associations were more evident when modeled as continuous outcomes than when categorized using clinically relevant cut points. In addition, longitudinal analyses indicated a significant increase in TNF-R2 levels over time to be associated with high blood lead level at the preceding visit.

CONCLUSIONS

Blood lead level may be related with CVD in healthy older men through its association with TNF-R2 levels. In addition, the magnitude of the association of blood lead level with TNF-R2 level increased with age in the study population.

A zebrafish model for the rapid evaluation of pro-oxidative and inflammatory death by lipopolysaccharide, oxidized low-density lipoproteins, and glycated high-density lipoproteins

Oxidation and inflammation are leading causes of nearly all chronic metabolic disorders, and play major roles in cardiovascular disease, cancer, and chronic age-dependent disease. High-density lipoprotein (HDL) and apolipoprotein (apo) A-I have strong antioxidant and anti-inflammatory properties in the plasma. Fructose-induced non-enzymatic glycation of apoA-I can lead to the production of dysfunctional apoA-I and HDL. To compare the physiologic effects of dysfunctional apoA-I and HDL, reconstituted HDL containing native apoA-I (nA-I) or glycated apoA-I (gA-I) was injected into zebrafish embryos in the presence of inflammatory molecules. Co-injection of reconstituted HDL containing VLDL and LDL gA-I (gA-I-rHDL) and lipopolysaccaride (LPS) resulted in acute embryo deaths, while rHDL containing nA-I (nA-I-rHDL) and LPS resulted in significantly enhanced survival. Co-injection of oxidized LDL (oxLDL) and nA-I-rHDL improved embryo survival, while co-injection of oxLDL and gA-I-rHDL aggravated inflammatory deaths. Furthermore, co-injection of oxLDL and HDL(2) (5 ng of protein) or HDL(3) (15 ng of protein) from the young group (22 ± 2 years old) showed significantly increased embryo survival compared with the same co-injection of HDL from the elderly group (71 ± 4 years old). In conclusion, our assay system provides a rapid and economic method to screen antioxidant and anti-inflammatory agents using zebrafish embryos.

Apolipoproteins: metabolic role and clinical biochemistry applications

Lipoprotein metabolism is dependent on apolipoproteins, multifunctional proteins that serve as templates for the assembly of lipoprotein particles, maintain their structure and direct their metabolism through binding to membrane receptors and regulation of enzyme activity. The three principal functions of lipoproteins are contribution to interorgan fuel (triglyceride) distribution (by means of the fuel transport pathway), to the maintenance of the extracellular cholesterol pool (by means of the overflow pathway) and reverse cholesterol transport. The most important clinical application of apolipoprotein measurements in the plasma is in the assessment of cardiovascular risk. Concentrations of apolipoprotein B and apolipoprotein AI (and their ratio) seem to be better markers of cardiovascular risk than conventional markers such as total cholesterol and LDL-cholesterol. Apolipoprotein measurements are also better standardized than the conventional tests. We suggest that measurements of apolipoprotein AI and apolipoprotein B are included as a part of the specialist lipid profile. We also suggest that lipoprotein (a) should be measured as part of the initial assessment of dyslipidaemias because of its consistent association with cardiovascular risk. Genotyping of apolipoprotein E isoforms remains useful in the investigation of mixed dyslipidaemias. Lastly, the role of postprandial metabolism is increasingly recognized in the context of atherogenesis, obesity and diabetes. This requires better markers of chylomicrons, very-low-density lipoproteins and remnant particles. Measurements of apolipoprotein B48 and remnant lipoprotein cholesterol are currently the key tests in this emerging field.

Laboratory investigation of dysfunctional HDL

High-density lipoprotein (HDL) particles are anti-atherosclerotic, by virtue of their functions in reverse cholesterol transportation, anti-inflammation and anti-oxidation. However, recent studies have cast doubt on the cardio-protective role of HDL. Structural modification and composition alteration of HDL due to chronic inflammation and acute phase responses may result in loss of normal biological function and even convert HDL into a pro-inflammatory and pro-oxidative agent. Therefore, the assessment of dysfunctional HDL has become a novel target to investigate the association between HDL and coronary artery disease risk. This review article summarizes the laboratory assessment of dysfunctional HDL.

Modified apolipoprotein (apo) A-I by artificial sweetener causes severe premature cellular senescence and atherosclerosis with impairment of functional and structural properties of apoA-I in lipid-free and lipid-bound state

Long-term consumption of artificial sweeteners (AS) has been the recent focus of safety concerns. However, the potential risk of the AS in cardiovascular disease and lipoprotein metabolism has not been investigated sufficiently. We compared the influence of AS (aspartame, acesulfame K, and saccharin) and fructose in terms of functional and structural correlations of apolipoprotein (apo) A-I and high-density lipoproteins (HDL), which have atheroprotective effects. Long-term treatment of apoA-I with the sweetener at physiological concentration (3 mM for 168 h) resulted in loss of antioxidant and phospholipid binding activities with modification of secondary structure. The AS treated apoA-I exhibited proteolytic cleavage to produce 26 kDa-fragment. They showed pro-atherogenic properties in acetylated LDL phagocytosis of macrophages. Each sweetener alone or sweetener-treated apoA-I caused accelerated senescence in human dermal fibroblasts. These results suggest that long-term consumption of AS might accelerate atherosclerosis and senescence via impairment of function and structure of apoA-I and HDL.

High-density lipoprotein (HDL) from elderly and reconstituted HDL containing glycated apolipoproteins A-I share proatherosclerotic and prosenescent properties with increased cholesterol influx

High-density lipoprotein (HDL) is a strong antioxidant, anti-inflammatory, and antisenescence molecule. However, in the current study, HDL from the elderly group (E-HDL) exhibited increased glycation with apolipoprotein (apo) A-I multimerization and decreased phospholipid content. Similarly, glycated apoA-I (gA-I) by fructosylation has a covalently multimerized band without a crosslinker and impaired phospholipid-binding ability. Treatment of human dermal fibroblasts and macrophages with E-HDL and gA-I caused more severe cellular senescence and foam cell formation, respectively; however, treatment with HDL from a young group (Y-HDL) and native apoA-I (nA-I) suppressed senescence and atherosclerosis. E-HDL(3) and reconstituted HDL (rHDL) containing gA-I showed enhanced cholesterol influx into macrophages compared with Y-HDL(3) and nA-I-rHDL. In conclusion, E-HDL and gA-I-rHDL share similar physiologic properties in macrophages and human dermal fibroblasts. E-HDL and gA-I-rHDL exacerbated cellular senescence and atherosclerosis with increased cellular cholesterol influx.

The new strategy for modulating dyslipidemia: consideration from updated understanding on high-density lipoprotein

With further researches on blood lipids and atherosclerosis, especially after the conception of "residual cardiovascular risk", high-density lipoprotein cholesterol (HDL-C) becomes a new therapeutic target against atherosclerosis. However, the failure of ILLUMINATE study that was targeted at raising HDL-C level disappointed cardiologists all over the world, which indicates the limitation of HDL-C concentration in representing HDL function. The updated understanding of HDL from "quantity" to "quality" brings a new cut-in point for integrative Chinese and Western medicine in preventing and treating dyslipidemia and atherosclerosis. In addition to highlighting statins in directly intervening low-density lipoprotein cholesterol, we should make full use of the superiority of Chinese medicine in overall regulation and individualized treatment to promote the self-healing capacity of the patients, which further regulates abnormity of both concentration and function of the whole blood lipid family to equilibrium. This new strategy for modulating dyslipidemia with mutual complement of advantages from Western and Chinese medicines will no doubt play an important role in future therapies.

Relative roles of various efflux pathways in net cholesterol efflux from macrophage foam cells in atherosclerotic lesions

PURPOSE OF REVIEW

Cholesterol efflux mechanisms are essential for macrophage cholesterol homeostasis. HDL, an important cholesterol efflux acceptor, comprises a class of heterogeneous particles that induce cholesterol efflux via distinct pathways. This review focuses on the understanding of the different cholesterol efflux pathways and physiological acceptors involved, and their regulation in atherosclerotic lesions.

RECENT FINDINGS

The synergistic interactions of ATP-binding cassette transporters A1 and G1 as well as ATP-binding cassette transporter A1 and scavenger receptor class B type I are essential for cellular cholesterol efflux and the prevention of macrophage foam cell formation. However, the importance of aqueous diffusion should also not be underestimated. Significant progress has been made in understanding the mechanisms underlying ATP-binding cassette A1-mediated cholesterol efflux and regulation of its expression and trafficking. Conditions locally in the atherosclerotic lesion, for example, lipids, cytokines, oxidative stress, and hypoxia, as well as systemic factors, including inflammation and diabetes, critically influence the expression of cholesterol transporters on macrophage foam cells. Furthermore, HDL modification and remodeling in atherosclerosis, inflammation, and diabetes impairs its function as an acceptor for cellular cholesterol.

SUMMARY

Recent advances in the understanding of the regulation of cholesterol transporters and their acceptors in atherosclerotic lesions indicate that HDL-based therapies should aim to enhance the activity of cholesterol transporters and improve both the quantity and quality of HDL.