LDL particle heterogeneity, and its association with other established cardiovascular risk factors in a young Indian industrial population

Two-sample Mendelian randomization analysis reveals causal relationships between blood lipids and venous thromboembolism

Venous thromboembolism (VTE) is a complex disease that can be classified into two subtypes: deep vein thrombosis (DVT) and pulmonary embolism (PE). Previous observational studies have shown associations between lipids and VTE, but causality remains unclear. Hence, by utilizing 241 lipid-related traits as exposures and data from the FinnGen consortium on VTE, DVT, and PE as outcomes, we conducted two-sample Mendelian randomization (MR) analysis to investigate causal relationships between lipids and VTE, DVT and PE. The MR results identified that fatty acid (FA) unsaturation traits (ratio of bis-allylic bonds to double bonds in lipids, and ratio of bis-allylic bonds to total fatty acids in lipids) were associated with VTE (odds ratio [OR]=1.21, 95% confidence interval [CI]: 1.15-1.27; OR=1.21, 95% CI: 1.13-1.30), DVT (OR=1.24, 95% CI: 1.16-1.33; OR= 1.26, 95% CI: 1.16-1.36) and PE (OR=1.18, 95% CI: 1.08-1.29; OR=1.18, 95% CI: 1.09-1.27). Phosphatidylcholines (PC) exhibit potential causal effects on VTE and PE. PC acyl-alkyl C40:4 (PC ae C40:4) was negatively associated with VTE (OR=0.79, 95% CI: 0.73-0.86), while PC diacyl C42:6 (PC aa C42:6) and PC acyl-alkyl C36:4 (PC ae C36:4) were positively associated with PE (OR=1.44, 95% CI: 1.20-1.72; OR=1.22, 95% CI: 1.10-1.35). Additionally, we found that medium LDL had a protective effect on VTE. Our study indicates that higher FA unsaturation may increase the risk of VTE, DVT, and PE. Different types of PC have either promotive or inhibitory effects on VTE and PE, contributing to a better understanding of the risk factors for VTE.

The effects of saturated fat intake from dairy on CVD markers: the role of food matrices

CVD is the leading cause of death worldwide, and is commonly associated with modifiable risk factors. Most studies to date examining link between food intake and risk of CVD, have focused on modulation of plasma cholesterol concentrations (total cholesterol (TC), LDL-C). However, recent studies suggest LDL particle size is a more sensitive risk marker for CVD with smaller, dense LDL particles reported as more atherogenic than larger, more buoyant LDL. Although dietary guidelines recommend SFA intake of < 10 % of total energy, this does not consider food source, with recent evidence suggesting differing, sometimes beneficial, lipid responses following consumption of SFA from dairy compared to other food sources. This may be from differences in the physical food matrices, the nutrient content of the foods, and/or how these components interact with each other, described as a 'dairy matrix effect'. Dietary fat not only raises LDL-C, but also HDL cholesterol (HDL-C), associated with reduced CVD risk. HDL particles are complex emulsions of lipids, proteins and microRNAs that exhibit atheroprotective properties. In addition, HDL particles exhibit a very heterogeneous proteomic composition, dependent on a person's disease state - with a more pro-inflammatory proteome evident in patients with established CVD. This review will discuss the evidence to date on the importance of the food matrix in modulating response to dietary SFA and impact on CVD risk factors. A focus on potential biomarker properties of lipoprotein particles beyond cholesterol and current use of such biomarkers in human nutrition research will be considered.

Association of LDL-cholesterol subfractions with cardiovascular disorders: a systematic review

BACKGROUND

Cardiovascular disorders (CVDs) are the leading cause of death worldwide. This study aimed to evaluate the association between low-density lipoprotein (LDL) subfractions and cardiovascular disorders.

METHODS

To ensure the rigor of the systematic review, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used. For this systematic review, a comprehensive search strategy was performed in important databases including PubMed, Scopus, Embase, International Statistical Institute (ISI) Web of Science, and google scholar from 2009 to February 2021. The following terms were used for systematic search: low-density lipoprotein, LDL, subfractions, subclasses, nuclear magnetic resonance, NMR, chromatography, high-pressure liquid, HPLC, cardiovascular disease, cerebrovascular, and peripheral vascular disease. Also, for evaluating the risk of bias, the Newcastle-Ottawa scale was employed.

RESULTS

At the end of the search process, 33 articles were included in this study. The results of most of the evaluated studies revealed that a higher LDL particle number was consistently associated with increased risk for cardiovascular disease, independent of other lipid measurements. Also, small dense LDL was associated with an increased risk of CVDs. There was no association between LDL subfraction and CVDs in a small number of studies.

CONCLUSIONS

Overall, it seems that the evaluation of LDL subclasses can be used as a very suitable biomarker for the assessment and diagnosis of cardiovascular diseases. However, further studies are required to identify the mechanisms involved.

Role of food matrix in modulating dairy fat induced changes in lipoprotein particle size distribution in a human intervention

BACKGROUND

Intake of dairy fat within the matrix of cheese lowered circulating LDL cholesterol concentration to a greater extent than the same components consumed separately as butter, protein, and calcium. However, circulating LDL cholesterol is not indicative of concentration or size of LDL particles (LDL-P), which are recognized as more sensitive risk markers of CVD.

OBJECTIVES

This was an exploratory analysis to investigate the role of the food matrix on lipoprotein particle size distribution, after a dairy fat intervention, in overweight adults aged ≥50 y.

METHODS

Lipoprotein particle size distribution was measured in fasting EDTA blood samples taken at week 0 (baseline) and at week 6, using NMR. In total, 127 participants (BMI ≥ 25 kg/m², aged ≥50 y) received ∼42 g dairy fat in 1 of 4 treatments: group A, 120 g full-fat cheddar cheese (FFCC); group B, reduced-fat cheese plus butter (RFC+B); group C, butter, calcium caseinate powder, and calcium supplement (CaCO₃) (BCC); or group D, 120 g FFCC (as per group A) but after a 6-wk washout period during which they excluded cheese before intervention.

RESULTS

Total VLDL and chylomicron particles (VLDL/CM-P) decreased after intervention. There was a strong correlation between reduced VLDL/CM-P and a reduction in small proatherogenic VLDL-P (r = 0.888, P < 0.001). Reductions in total LDL-P were associated with a reduction in small LDL-P and, to a lesser extent, with large LDL-P. There was a significant main effect of treatment for change in intermediate-density lipoprotein particles (IDL-P) after the intervention (P = 0.023) between groups B and D (-46.86 ± 30.38 and 40.69 ± 32.72 nmol/L, respectively). HDL particle (HDL-P) parameters (diameter, concentration, or size distribution) were not affected by diet.

CONCLUSIONS

Our findings indicate that reductions in LDL cholesterol observed with dairy fat consumption are driven by reductions in LDL-P concentration. A trend toward a less atherogenic profile was observed, but there was no clear effect of the individual food matrices. This trial was registered at ISRCTN as ISRCTN86731958.

Association between Lp(a) and small dense LDL in menopausal women without metabolic syndrome

Background: Lipoprotein (a) (Lp [a]) is associated with premature atherosclerosis in menopausal women without metabolic syndrome (MS). MS is the main confounder in the relationship between Lp(a) and atherosclerosis in menopausal women. We have evaluated the relationship between Lp(a) and small dense-low density lipoprotein (sd-LDL) in 228 menopausal women participating to Progetto Atena. Methods: Lp(a) was measured and LDL particle separation was performed: mean LDL diameter and LDL score (% of sd-LDL) particles calculated. Results: Women without MS and elevated Lp(a) have increased number of sd-LDL (p < .05) and higher LDL score compared with those below the median of the studied population (p < .05). The association between Lp(a) and sd-LDL was evaluated taking into account different adjustment models. Women with elevated levels of Lp(a) show the following OR of having a small LDL diameter (in the lowest quartile): 1.02, p = .003; adjusted for age; 1.02, p = .002; adjusted for age, and triglycerides, or a high LDL score (in the highest quartile): 1.02, p = .006; adjusted for age; 1.02, p = .002; adjusted for age and triglycerides. Conclusions: In this group of menopausal women without MS, the independent association of Lp(a) with sd-LDL might explain at least in part the association of Lp(a) with premature atherosclerosis.