Cholesterol forms and traditional lipid profile for projection of atherogenic dyslipidemia: lipoprotein subfractions and erythrocyte membrane cholesterol

Unmasking the morphological alteration of erythrocytes among women suffering from PCOS

Dyslipidemia is frequently observed in polycystic ovarian syndrome (PCOS). Changes in plasma lipid levels potentially alter erythrocyte membrane lipid composition due to lack of inbuilt lipid synthesis machinery. Therefore, development of morphologically altered erythrocytes in PCOS patients with dyslipidemia is expected. However, this has not been established so far. So, we took this opportunity to explore the morphological alterations among dyslipidemic PCO women. We recruited thirty-five dyslipidemic PCOS women (satisfying Rotterdam criteria, without medication) and twenty-five age-matched healthy controls. Scanning electron microscopy revealed a significant increase in the number of stomatocytes, acanthocytes, and echinocytes in the PCO group. PCO group showed a considerable decrease in plasma antioxidant levels. Elevated lipid peroxidation, protein carbonylation, and decreased free thiol group in erythrocyte membrane in PCOS suggest oxidative degradation of the erythrocyte membrane. Elevated intracellular ROS levels, increased methemoglobin formation, and a decrease in NADPH methemoglobin reductase in PCOS also indicate altered physicochemical property of hemoglobin due to oxidative overload. Additionally, these patients exhibit a rise in erythrocyte membrane cholesterol and triglyceride, which promotes the membrane to become less fluidic and less fragile. Thus, these results corroborate a potential role in altering erythrocyte morphology among dyslipidemic PCO women.

High-density lipoprotein cholesterol subfraction HDL2 is associated with improved endothelial function in systemic lupus erythematosus

OBJECTIVE

Patients with systemic lupus erythematosus (SLE) have increased risk of premature atherosclerosis but the exact mechanisms remains unclear. Flow-mediated dilatation (FMD) is an established non-invasive assessment of vascular endothelial function. Lipoprotein subfractions may be better predictors of FMD than conventional cholesterol measurements. We tested the hypothesis that lipoprotein subfractions are independently associated with FMD.

METHODS

Forty-one consecutive adult patients with SLE without known cardiovascular risk factors or disease were recruited in this cross-sectional study. Endothelial function and early atherosclerosis were assessed by brachial FMD and common carotid artery (CCA) intima-media thickness (IMT). High-density lipoprotein (HDL)/low-density lipoprotein (LDL) subfractions were measured. Machine learning models were also constructed to predict FMD and CCA IMT.

RESULTS

Median FMD was 4.48% (IQR 5.00%) while median IMT was 0.54 mm (IQR 0.12 mm). Univariate analysis showed lower LDL1 (r=-0.313, p<0.05) and higher HDL2 subfractions (r=0.313, p<0.05) were significantly associated with higher log-transformed FMD. In a multiple linear regression model, HDL2 (β=0.024, SE=0.012, p<0.05) remained an independent predictor of higher FMD after adjusting for age, body mass index, LDL1 and systolic blood pressure. The machine learning model included parameters such as HDL2 (positive association), prednisolone dose, LDL cholesterol and LDL1 for prediction of FMD (r=0.433, p<0.01). Age, LDL cholesterol and systolic blood pressure were independently associated with higher CCA IMT after adjusting for body mass index and HDL2.

CONCLUSIONS

HDL 2, a large HDL particle, was independently associated with greater FMD and may be a biomarker of vascular health in SLE.

Oral Supplement Containing Hydroxytyrosol and Punicalagin Improves Dyslipidemia in an Adult Population without Co-Adjuvant Treatment: A Randomized, Double-Blind, Controlled and Crossover Trial

Hydroxytyrosol (HT) and punicalagin (PC) exert cardioprotective and antiatherosclerotic effects. This study evaluated the effect of an oral supplement containing HT and PC (SAx) on dyslipidemia in an adult population. A randomized, double-blind, controlled, crossover trial was conducted over a 20-week period. SAx significantly reduced the plasma levels of triglycerides (TG) in subjects with hypertriglyceridemia (≥150 mg/dL) (from 200.67 ± 51.38 to 155.33 ± 42.44 mg/dL; p < 0.05), while no such effects were observed in these subjects after the placebo. SAx also significantly decreased the plasma levels of low-density lipoprotein cholesterol (LDL-C) in subjects with high plasma levels of LDL-C (≥160 mg/dL) (from 179.13 ± 16.18 to 162.93 ± 27.05 mg/dL; p < 0.01), while no such positive effect was observed with the placebo. In addition, the placebo significantly reduced the plasma levels of high-density lipoprotein cholesterol (HDL-C) in the total population (from 64.49 ± 12.65 to 62.55 ± 11.57 mg/dL; p < 0.05), while SAx significantly increased the plasma levels of HDL-C in subjects with low plasma levels of HDL-C (<50 mg/dL) (from 44.25 ± 3.99 to 48.00 ± 7.27 mg/dL; p < 0.05). In conclusion, the supplement containing HT and PC exerted antiatherosclerotic and cardio-protective effects by considerably improving dyslipidemia in an adult population, without co-adjuvant treatment or adverse effects.

Influence of Disorders of Fatty Acid Metabolism, Arterial Wall Hypoxia, and Intraplaque Hemorrhages on Lipid Accumulation in Atherosclerotic Vessels

The review describes a number of competing views on the main causes of cholesterol accumulation in atherosclerotic vessels. On the one hand, unregulated cholesterol influx into arterial intima is primarily related to the increasing proportion of atherogenic lipoproteins in the lipoprotein spectrum of blood. On the other hand, the leading role in this process is assigned to the increased permeability of endothelium for atherogenic lipoproteins. The increased ability of arterial intima connective tissue to bind atherogenic blood lipoproteins is also considered to be the leading cause of cholesterol accumulation in the vascular wall. The key role in cholesterol accumulation is also assigned to unregulated (by a negative feedback mechanism) absorption of atherogenic lipoproteins by foam cells. It is suggested that the main cause of abundant cholesterol accumulation in atherosclerotic vessels is significant inflow of this lipid into the vascular wall during vasa vasorum hemorrhages.

The article also provides arguments, according to which disorder of fatty acid metabolism in arterial wall cells can initiate accumulation of neutral lipids in them, contribute to the inflammation and negatively affect the mechanical conditions around the vasa vasorum in the arterial walls. As a result, the impact of pulse waves on the luminal surface of the arteries will lead to frequent hemorrhages of these microvessels. At the same time, adaptive-muscular intima hyperplasia, which develops in arterial channel areas subjected to high hemodynamic loads, causes local hypoxia in a vascular wall. As a result, arterial wall cells undergo even more severe lipid transformation. Hypoxia also stimulates vascularization of the arterial wall, which contributes to hemorrhages in it. With hemorrhages, free erythrocyte cholesterol penetrates into the forming atherosclerotic plaque, a part of this cholesterol forms cholesterol esters inside the arterial cells. The saturation of erythrocyte membranes with this lipid in conditions of hypercholesterolemia and atherogenic dyslipoproteinemia contributes to the process of cholesterol accumulation in arteries.