Low-density lipoprotein (LDL) particle size in healthy prepubertal children: the STRIP study

Evolving concepts of low-density lipoprotein: From structure to function

BACKGROUND

Low-density lipoprotein (LDL) is a central player in atherogenesis and has long been referred to as 'bad cholesterol.' However, emerging evidence indicates that LDL functions in multifaceted ways beyond cholesterol transport that include roles in inflammation, immunity, and cellular signaling. Understanding LDL's structure, metabolism and function is essential for advancing cardiovascular disease research and therapeutic strategies.

METHODS

This narrative review examines the history, structural properties, metabolism and functions of LDL in cardiovascular health and disease. We analyze key milestones in LDL research, from its early identification to recent advancements in molecular biology and omics-based investigations. Structural and functional insights are explored through imaging, proteomic analyses and lipidomic profiling, providing a deeper understanding of LDL heterogeneity.

RESULTS

Low-density lipoprotein metabolism, from biosynthesis to receptor-mediated clearance, plays a crucial role in lipid homeostasis and atherogenesis. Beyond cholesterol transport, LDL contributes to plaque inflammation, modulates adaptive immunity and regulates cellular signaling pathways. Structural studies reveal its heterogeneous composition, which influences its pathogenic potential. Evolving perspectives on LDL redefine its clinical significance, affecting cardiovascular risk assessment and therapeutic interventions.

CONCLUSIONS

A holistic understanding of LDL biology challenges traditional perspectives and underscores its complexity in cardiovascular health. Future research should focus on further elucidating LDL's structural and functional diversity to refine risk prediction models and therapeutic strategies, ultimately improving cardiovascular outcomes.

Personalized Dietary Recommendations Based on Lipid-Related Genetic Variants: A Systematic Review

Background

Obesity and dyslipidemias are risk factors for developing cardiovascular diseases, the leading causes of morbidity and mortality worldwide. The pathogenesis of these diseases involves environmental factors, such as nutrition, but other aspects like genetic polymorphisms confer susceptibility to developing obesity and dyslipidemias. In this sense, nutrigenetics is being used to study the influence of genetic variations on the circulating lipid responses promoted by certain nutrients or foods to provide specific dietary strategies considering the genetic factors in personalized nutrition interventions.

Objective

To identify throughout a systematic review the potential nutrigenetic recommendations that demonstrate a strong interaction between gene-diet and circulating lipid variations.

Methods

This systematic review used the PRISMA-Protocol for manuscript research and preparation using PubMed and ScienceDirect databases. Human studies published in English from January 2010 to December 2020 were included. The main results were outcomes related to gene-diet interactions and plasmatic lipids variation.

Results

About 1,110 articles were identified, but only 38 were considered to fulfill the inclusion criteria established based on the reported data. The acquired information was organized based on gene-diet interaction with nutrients and components of the diet and dietary recommendation generated by each interaction: gene-diet interaction with dietary fats, carbohydrates or dietary fiber, gene-diet interaction with nutraceutical or dietary supplementation, and gene-diet interaction with proteins.

Conclusion

Findings included in this systematic review indicated that a certain percentage of dietary macronutrients, the consumption of specific amounts of polyunsaturated or monounsaturated fatty acids, as well as the ingestion of nutraceuticals or dietary supplements could be considered as potential strategies for the development of a wide range of nutrigenetic interventions since they have a direct impact on the blood levels of lipids. In this way, specific recommendations were identified as potential tools in developing precision diets and highlighted the importance of personalized nutrition. These recommendations may serve as a possible strategy to implement as dietary tools for the preventive treatment and control alterations in lipid metabolism.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021248816, identifier [CRD42021248816].

Cardiometabolic Associations between Physical Activity, Adiposity, and Lipoprotein Subclasses in Prepubertal Norwegian Children

Lipoprotein subclasses possess crucial cardiometabolic information. Due to strong multicollinearity among variables, little is known about the strength of influence of physical activity (PA) and adiposity upon this cardiometabolic pattern. Using a novel approach to adjust for covariates, we aimed at determining the "net" patterns and strength for PA and adiposity to the lipoprotein profile. Principal component and multivariate pattern analysis were used for the analysis of 841 prepubertal children characterized by 26 lipoprotein features determined by proton nuclear magnetic resonance spectroscopy, a high-resolution PA descriptor derived from accelerometry, and three adiposity measures: body mass index, waist circumference to height, and skinfold thickness. Our approach focuses on revealing and validating the underlying predictive association patterns in the metabolic, anthropologic, and PA data to acknowledge the inherent multicollinear nature of such data. PA associates to a favorable cardiometabolic pattern of increased high-density lipoproteins (HDL), very large and large HDL particles, and large size of HDL particles, and decreasedtriglyceride, chylomicrons, very low-density lipoproteins (VLDL), and their subclasses, and to low size of VLDL particles. Although weakened in strength, this pattern resists adjustment for adiposity. Adiposity is inversely associated to this pattern and exhibits unfavorable associations to low-density lipoprotein (LDL) features, including atherogenic small and very small LDL particles. The observed associations are still strong after adjustment for PA. Thus, lipoproteins explain 26.0% in adiposity after adjustment for PA compared to 2.3% in PA after adjustment for adiposity.

Plant sterols-enriched diet decreases small, dense LDL-cholesterol levels in children with hypercholesterolemia: a prospective study

Background

Small dense low density lipoprotein-cholesterol (sdLDL-C) molecules are more atherogenic compared with large buoyant ones. Phytosterols-enriched diets are effective in decreasing total cholesterol (TC) and low density lipoprotein-cholesterol (LDL-C) concentrations in hyperlipidemic children without significant adverse effects. Limited data on the impact of such a diet on sdLDL-C levels is available in adults while there are no reports concerning children. The purpose of this study is to prospectively evaluate the effect of the daily consumption of 2 g of plant sterols on sdLDL-C levels in children with hypercholesterolemia.

Methods

Fifty-nine children, 25 with LDL-C ≥ 3.4 mmol/l (130 mg/dl) and 34 with LDL-C < 3.4 mmol/l, aged 4.5-15.9 years, were included in the study. A yogurt-drink enriched with 2 g of plant sterols was added to the daily diet of hypercholesterolemic children and 6–12 months later lipid profiles were reassessed. Direct quantitative methods were used to measure LDL-C and sdLDL-C levels.

Results

The consumption of plant sterols reduced sdLDL-C significantly (p < 0.001), but levels remained higher compared with controls (p < 0.001). TC, LDL-C, non high density lipoprotein-cholesterol (NonHDL-C) and apolipoprotein B (ApoB) levels also decreased significantly (p < 0.05). The median reduction of sdLDL-C and LDL-C was 16.6% and 13%, respectively. These variables decreased >10% in sixteen children (64%), independently from baseline levels, sex, age and body mass index (BMI). High density lipoprotein-cholesterol (HDL-C), lipoprotein a [Lp(a)], and triglycerides (TGs) levels remained unaffected.

Conclusions

Plant sterols decrease sdLDL-C significantly and may be beneficial for children with hypercholesterolemia.

Is the metabolic syndrome caused by a high fructose, and relatively low fat, low cholesterol diet?

The metabolic syndrome (MetS) is manifested by a lipid triad which includes elevated serum triglycerides, small LDL particles, and low high-density lipoprotein (HDL) cholesterol, by central obesity (central adiposity), insulin resistance, glucose intolerance and elevated blood pressure, and it is associated with an increased risk of type 2 diabetes and coronary heart disease. We have developed a new hypothesis regarding MetS as a consequence of a high intake in carbohydrates and food with a high glycemic index, particularly fructose, and relatively low intake of cholesterol and saturated fat. We support our arguments through animal studies which have shown that exposure of the liver to increased quantities of fructose leads to rapid stimulation of lipogenesis and accumulation of triglycerides. The adipocytes store triglycerides in lipid droplets, leading to adipocyte hypertrophy. Adipocyte hypertrophy is associated with macrophage accumulation in adipose tissue. An important modulator of obesity-associated macrophage responses in white adipose tissue is the death of adipocytes. Excess exposure to fructose intake determines the liver to metabolize high doses of fructose, producing increased levels of fructose end products, like glyceraldehyde and dihydroxyacetone phosphate, that can converge with the glycolytic pathway. Fructose also leads to increased levels of advanced glycation end products. The macrophages exposed to advanced glycation end products become dysfunctional and, on entry into the artery wall, contribute to plaque formation and thrombosis.

Tracking and determinants of LDL particle size in healthy children from 7 to 11 years of age: the STRIP Study

Serum low-density lipoprotein (LDL) particle composition varies according to lifestyle and age. To analyze its long-term tracking, we studied LDL particle size consecutively in 100 children at the ages of 7, 9 and 11 years using a high-resolution 3% polyacrylamide gel tube, electrophoresis method, searching also for long-term determinants of the particle size. The mean LDL particle sizes at 7 and 9 years, and at 7 and 11 years correlated directly (r=0.72 and 0.39, respectively). The probability that children would remain in the same LDL particle size tertile between 7 and 11 years of age was 48% (p=0.008). Longitudinally, total, high-density lipoprotein (HDL) and LDL cholesterol concentrations and body mass index (BMI) associated directly with mean LDL particle size, and triglyceride concentration and triglyceride/HDL cholesterol ratio correlated inversely. A shift from pre-puberty to puberty was associated with an increase in LDL particle size. Sex, serum insulin concentration, or energy nutrient intakes did not associate with LDL particle size. In conclusion, although mean LDL particle size tracks in 7- to 11-year-old healthy children, changes in serum triglycerides, HDL, LDL, and total cholesterol concentration, BMI, and pubertal status all modify LDL particle size.