The associations of cholesterol metabolism and plasma plant sterols with all-cause and cardiovascular mortality

Genotype-based "virtual" metabolomics in a clinical biobank identifies novel metabolite-disease associations

Introduction: Circulating metabolites act as biomarkers of dysregulated metabolism and may inform disease pathophysiology. A portion of the inter-individual variability in circulating metabolites is influenced by common genetic variation. We evaluated whether a genetics-based "virtual" metabolomics approach can identify novel metabolite-disease associations. Methods: We examined the association between polygenic scores for 724 metabolites with 1,247 clinical phenotypes in the BioVU DNA biobank, comprising 57,735 European ancestry and 15,754 African ancestry participants. We applied Mendelian randomization (MR) to probe significant relationships and validated significant MR associations using independent GWAS of candidate phenotypes. Results and Discussion: We found significant associations between 336 metabolites and 168 phenotypes in European ancestry and 107 metabolites and 56 phenotypes in African ancestry. Of these metabolite-disease pairs, MR analyses confirmed associations between 73 metabolites and 53 phenotypes in European ancestry. Of 22 metabolitephenotype pairs evaluated for replication in independent GWAS, 16 were significant (false discovery rate p < 0.05). These included associations between bilirubin and X-21796 with cholelithiasis, phosphatidylcholine (16:0/22:5n3,18:1/20:4) and arachidonate with inflammatory bowel disease and Crohn's disease, and campesterol with coronary artery disease and myocardial infarction. These associations may represent biomarkers or potentially targetable mediators of disease risk.

Genotype-based "virtual" metabolomics in a clinical biobank identifies novel metabolite-disease associations

Circulating metabolites act as biomarkers of dysregulated metabolism, and may inform disease pathophysiology. A portion of the inter-individual variability in circulating metabolites is influenced by common genetic variation. We evaluated whether a genetics-based "virtual" metabolomics approach can identify novel metabolite-disease associations. We examined the association between polygenic scores for 726 metabolites (derived from OMICSPRED) with 1,247 clinical phenotypes in 57,735 European ancestry and 15,754 African ancestry participants from the BioVU DNA Biobank. We probed significant relationships through Mendelian randomization (MR) using genetic instruments constructed from the METSIM Study, and validated significant MR associations using independent GWAS of candidate phenotypes. We found significant associations between 336 metabolites and 168 phenotypes in European ancestry and 107 metabolites and 56 phenotypes among African ancestry. Of these metabolite-disease pairs, MR analyses confirmed associations between 73 metabolites and 53 phenotypes in European ancestry. Of 22 metabolite-phenotype pairs evaluated for replication in independent GWAS, 16 were significant (false discovery rate p<0.05). Validated findings included the metabolites bilirubin and X-21796 with cholelithiasis, phosphatidylcholine(16:0/22:5n3,18:1/20:4) and arachidonate(20:4n6) with inflammatory bowel disease and Crohn's disease, and campesterol with coronary artery disease and myocardial infarction. These associations may represent biomarkers or potentially targetable mediators of disease risk.

Genotype-based "virtual" metabolomics in a clinical biobank identifies novel metabolite-disease associations

Circulating metabolites act as biomarkers of dysregulated metabolism, and may inform disease pathophysiology. A portion of the inter-individual variability in circulating metabolites is influenced by common genetic variation. We evaluated whether a genetics-based "virtual" metabolomics approach can identify novel metabolite-disease associations. We examined the association between polygenic scores for 726 metabolites (derived from OMICSPRED) with 1,247 clinical phenotypes in 57,735 European ancestry and 15,754 African ancestry participants from the BioVU DNA Biobank. We probed significant relationships through Mendelian randomization (MR) using genetic instruments constructed from the METSIM Study, and validated significant MR associations using independent GWAS of candidate phenotypes. We found significant associations between 336 metabolites and 168 phenotypes in European ancestry and 107 metabolites and 56 phenotypes among African ancestry. Of these metabolite-disease pairs, MR analyses confirmed associations between 73 metabolites and 53 phenotypes in European ancestry. Of 22 metabolite-phenotype pairs evaluated for replication in independent GWAS, 16 were significant (false discovery rate p<0.05). Validated findings included the metabolites bilirubin and X-21796 with cholelithiasis, phosphatidylcholine(16:0/22:5n3,18:1/20:4) and arachidonate(20:4n6) with inflammatory bowel disease and Crohn's disease, and campesterol with coronary artery disease and myocardial infarction. These associations may represent biomarkers or potentially targetable mediators of disease risk.

Remnant cholesterol, but not other cholesterol parameters, is associated with gestational diabetes mellitus in pregnant women: a prospective cohort study

OBJECTIVE

No evidence has been found of a relationship between remnant cholesterol (RC) and the likelihood of gestational diabetes mellitus (GDM) in pregnant women. The aim of our study was to investigate the link between serum RC at 12-14 weeks of gestation and the risk of GDM.

METHODS

This was a secondary analysis with data from a prospective cohort study in Korea. A total of 590 single pregnant women attending two hospitals in Korea, up to 14 weeks gestation, from November 2014 to July 2016 were included in the study. The formula used to calculate RC in detail was RC (mg/dL) = TC (mg/dL)-HDL-c (mg/dL)-LDL-c (mg/dL). Logistic regression models were employed to examine the relationship between RC and GDM and explore the association between other lipoprotein cholesterol parameters and the risk of GDM. Furthermore, receiver operating characteristic (ROC) analysis was performed to assess the ability of RC to identify GDM. Additionally, sensitivity and subgroup analyses were conducted.

RESULTS

The mean age of participants was 32.06 ± 3.80 years. The median of RC was 34.66 mg/dL. 37 pregnant women (6.27%) were eventually diagnosed with GDM. Multivariate adjusted logistic regression analysis showed that RC was positively associated with the risk of GDM (OR = 1.458, 95% CI 1.221, 1.741). There was no significant association between other lipoprotein cholesterols (including TC, LDL-c, HDL-c) and the risk of GDM. The area under the ROC curve for RC as a predictor of GDM was 0.8038 (95% CI 0.7338-0.8738), and the optimal RC cut-off was 24.30 mg/dL. Our findings were demonstrated to be robust by performing a series of sensitivity analyses.

CONCLUSION

Serum RC levels at 12-14 weeks of gestation are positively associated with GDM risk in pregnant women. RC in early pregnancy is an early warning indicator of GDM in pregnant women, especially those with normal HDL-c, LDL-c, and TC that are easily overlooked. There is a high risk of developing GDM in pregnant women whose RC is more than 24.30 mg/dL. This study may help optimize GDM prevention in pregnant women and facilitate communication between physicians, pregnant patients, and their families.

Cholesterol Metabolism in Aging and Age-Related Disorders

All mammalian cell membranes contain cholesterol to maintain membrane integrity. The transport of this hydrophobic lipid is mediated by lipoproteins. Cholesterol is especially enriched in the brain, particularly in synaptic and myelin membranes. Aging involves changes in sterol metabolism in peripheral organs and also in the brain. Some of those alterations have the potential to promote or to counteract the development of neurodegenerative diseases during aging. Here, we summarize the current knowledge of general principles of sterol metabolism in humans and mice, the most widely used model organism in biomedical research. We discuss changes in sterol metabolism that occur in the aged brain and highlight recent developments in cell type-specific cholesterol metabolism in the fast-growing research field of aging and age-related diseases, focusing on Alzheimer's disease. We propose that cell type-specific cholesterol handling and the interplay between cell types critically influence age-related disease processes.

Plant Sterols and Plant Stanols in Cholesterol Management and Cardiovascular Prevention

Atherosclerotic cardiovascular disease (ASCVD) remains the major mortality cause in developed countries with hypercholesterolaemia being one of the primary modifiable causes. Lifestyle intervention constitutes the first step in cholesterol management and includes dietary modifications along with the use of functional foods and supplements. Functional foods enriched with plant sterols/stanols have become the most widely used nonprescription cholesterol-lowering approach, despite the lack of randomized trials investigating their long-term safety and cardiovascular efficacy. The cholesterol-lowering effect of plant-sterol supplementation is well-established and a potential beneficial impact on other lipoproteins and glucose homeostasis has been described. Nevertheless, experimental and human observational studies investigating the association of phytosterol supplementation or circulating plant sterols with various markers of atherosclerosis and ASCVD events have demonstrated controversial results. Compelling evidence from recent genetic studies have also linked elevated plasma concentrations of circulating plant sterols with ASCVD presence, thus raising concerns about the safety of phytosterol supplementation. Thus, the aim of this review is to provide up-to-date data on the effect of plant sterols/stanols on lipid-modification and cardiovascular outcomes, as well as to discuss any safety issues and practical concerns.

Phytosterols and Cardiovascular Risk Evaluated against the Background of Phytosterolemia Cases-A German Expert Panel Statement

Phytosterols (PSs) have been proposed as dietary means to lower plasma LDL-C. However, concerns are raised that PSs may exert atherogenic effects, which would offset this benefit. Phytosterolemia was thought to mimic increased plasma PSs observed after the consumption of PS-enriched foods. This expert statement examines the possibility of specific atherogenicity of PSs based on sterol metabolism, experimental, animal, and human data. Observational studies show no evidence that plasma PS concentrations would be associated with an increased risk of atherosclerosis or cardiovascular (CV) events. Since variants of the ABCG5/8 transporter affect the absorption of cholesterol and non-cholesterol sterols, Mendelian randomization studies examining the effects of ABCG5/8 polymorphisms cannot support or refute the potential atherogenic effects of PSs due to pleiotropy. In homozygous patients with phytosterolemia, total PS concentrations are ~4000% higher than under physiological conditions. The prevalence of atherosclerosis in these individuals is variable and may mainly relate to concomitant elevated LDL-C. Consuming PS-enriched foods increases PS concentrations by ~35%. Hence, PSs, on a molar basis, would need to have 20-40 times higher atherogenicity than cholesterol to offset their cholesterol reduction benefit. Based on their LDL-C lowering and absence of adverse safety signals, PSs offer a dietary approach to cholesterol management. However, their clinical benefits have not been established in long-term CV endpoint studies.

Plant sterol hyperabsorption caused by uncontrolled diabetes in a patient with a heterozygous ABCG5 variant

Plant sterol intake is widely recommended in patients with cardiovascular risk factors based on the inhibitory effect on intestinal cholesterol absorption. Although plant sterols, once absorbed, can promote atherosclerosis, their intake is believed to be safe because of poor absorption, except in rare hyperabsorbers with homozygous ABCG5/8 mutations. We report a case of new-onset type 1 diabetes accompanied by hypercholesterolemia. At the initial presentation with diabetic ketoacidosis, the patient showed marked hypercholesterolemia. Whole-exome sequencing revealed a heterozygous pathogenic variant in ABCG5 (p.R419H). The initial serum plant sterol levels were markedly high (sitosterol, 32.5 μg/mL; campesterol, 66.0 μg/mL) close to the range observed in patients with homozygous ABCG5/8 mutations, which were largely reduced by insulin treatment without ezetimibe. The addition of ezetimibe normalized plant sterol levels. These findings provide the first evidence that uncontrolled diabetes plays a causal role in the pathogenesis of phytosterolemia.

Phytosterols and Cardiovascular Disease

Purpose of Review

Coronary heart disease is the leading cause of mortality worldwide. Elevated blood cholesterol levels are not only the major but also the best modifiable cardiovascular risk factor. Lifestyle modifications which include a healthy diet are the cornerstone of lipid-lowering therapy. So-called functional foods supplemented with plant sterols lower blood cholesterol levels by about 10–15%.

Recent Findings

In the recent revision of the ESC/EAS dyslipidemia guideline 2019, plant sterols are recommended for the first time as an adjunct to lifestyle modification to lower blood cholesterol levels. However, the German Cardiac Society (DGK) is more critical of food supplementation with plant sterols and calls for randomized controlled trials investigating hard cardiovascular outcomes. An increasing body of evidence suggests that plant sterols per se are atherogenic.

Summary

This review discusses this controversy based on findings from in vitro and in vivo studies, clinical trials, and genetic evidence.

Metabolic signatures of cholesterol biosynthesis and absorption in patients with coronary artery disease

Due to the biochemical importance of cholesterol homeostasis in cardiovascular disease (CVD), this study was aimed to identify metabolic signatures of serum sterols according to atherosclerotic CVD severity. Biogically active free cholesterol and its 11 analogues in serum samples obtained from subjects who underwent cardiovascular intervention were quantitatively evaluated by gas chromatography-mass spectrometry (GCMS). Study groups were divided by 29 patients with stable angina (SA), 35 patients with acute coronary syndrome (ACS), and 41 controls. In all subjects, serum levels of cholesterol and its upstream precursors of 7-dehydrocholesterol, lathosterol, and lanosterol were closely associated with CVD risk factors, such as total cholesterol, low-density lipoprotein cholesterol (LDL-C), and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio (r = 0.407 ∼ 0.684, P < 0.03 for all). Metabolic ratios of lathosterol/cholesterol (control = 55.75 ± 34.34, SA = 51.04 ± 34.93, ACS = 36.52 ± 22.00; P < 0.03) and lanosterol/cholesterol (control = 12.27 ± 7.43, SA = 10.97 ± 9.13, ACS = 8.01 ± 5.82; P < 0.03), were remarkably decreased. Both metabolic ratios and individual concentrations of lathosterol and lanosterol were also decreased in subjects with statin treatment than those in the control group without statin treatment (P < 0.05 for all), whereas three metabolic ratios of dietary sterols (sitosterol, campesterol, and stigmasterol) to free cholesterol were increased after statin therapy (P < 0.05 for all) in both SA and ACS groups. The present metabolic signatures suggest that both lathosterol/cholesterol and lanosterol/cholesterol ratios corresponding to cholesterol biosynthesis may reflect statin response. Individual dietary sterols to cholesterol ratios resulted in higher intestinal cholesterol absorption after statin therapy.

Cross-Sectional Study of Plant Sterols Intake as a Basis for Designing Appropriate Plant Sterol-Enriched Food in Indonesia

Coronary heart disease (CHD) is one of the leading causes of mortality in many low-income and middle-income countries, including Indonesia, with elevated blood cholesterol level being one of significant risk factors for this condition. The problem should be addressed by combining healthy lifestyle and diet, where functional foods having a cholesterol-lowering activity could play a significant role. A group of compounds that had been proven to show cholesterol-lowering ability are plant sterols. To develop more suitable functional foods that could substantially contribute to hypercholesterolemia prevention in Indonesian population, up-to-date data about plant sterols dietary intake are required, and were not available until this research was done. This study aimed to estimate daily plant sterols intake and to determine the consumption pattern of foods containing plant sterols in rural and urban area of Bogor, West Java, Indonesia. The research was conducted with a cross-sectional design, with 200 respondents. The study revealed that the level of plant sterols intake in Bogor reached on average 229.76 mg/day and was not significantly different between urban and rural area. Cereals, vegetables, and fruit products were the main food sources of plant sterols in both areas. In addition, a list of several surveyed food items possible to be enriched with plant sterols was developed within the study. These results provide baseline data to develop functional foods fortified with plant sterols suitable for the Indonesian needs and taste. However, further studies are needed to confirm efficacy and safety of introducing such phytosterol-enriched products into a habitual diet, especially considering possible long-term side effects of plant sterol treatment.

Multi-dimensional characterization and identification of sterols in untargeted LC-MS analysis using all ion fragmentation technology

Sterols are an important type of lipids, and play many important roles in physiological and pathological processes. However, comprehensive analysis of sterols especially identification of unknown sterols is challenging. In this work, LC-MS with all ion fragmentation (AIF) technology was developed for untargeted analysis of sterols in biological samples. AIF technology provided holistic and multi-dimensional characterization for both knowns and unknowns sterols, including accurate m/z, isotope pattern, retention time (RT), and co-eluted peak profiles between MS1 and MS2 ions in one analysis. We further developed an analysis strategy by integrating the multi-dimensional properties to support unambiguous identification of sterols, including distinguishing sterol isomers. The developed strategy enabled to identify a total of 23 sterols in mouse samples, and quantified 19 sterols in mouse liver tissues. More importantly, we demonstrated that AIF based multi-dimensional analysis provided a possibility to identify sterols without chemical standards and facilitated to discover novel compounds with sterol-like structures in biological samples. In summary, we employed the LC-MS based AIF technology to develop multi-dimensional characterization and identification of both known and unknown sterols in complex biological samples. The comprehensive analysis of sterols facilitates to provide molecular insights to many physiological and pathological activities in biology.

Exploring the effect of vitamin D3 supplementation on surrogate biomarkers of cholesterol absorption and endogenous synthesis in patients with type 2 diabetes-randomized controlled trial

BACKGROUND

Inverse associations have been reported between serum 25-hydroxyvitamin D [25(OH)D] and circulating cholesterol concentrations in observational studies. Postulated mechanisms include reduced bioavailability of intestinal cholesterol and alterations in endogenous cholesterol synthesis.

OBJECTIVE

To explore the effect of daily supplementation with 4000 IU/d vitamin D3 for 24 wk on surrogate biomarkers of cholesterol absorption (campesterol and β-sitosterol) and endogenous synthesis (lathosterol and desmosterol).

METHODS

Ancillary study of The Vitamin D for Established Type 2 Diabetes (DDM2) trial. Patients with established type 2 diabetes (N = 127, 25-75 y, BMI 23-42 kg/m2) were randomly assigned to receive either 4000 IU vitamin D3 or placebo daily for 24 wk. Of participants without changes in cholesterol-lowering medications (n = 114), plasma surrogate cholesterol absorption and endogenous synthesis biomarker concentrations were measured and merged with available measures of serum LDL cholesterol and HDL cholesterol concentrations.

RESULTS

At week 24, vitamin D3 supplementation significantly increased 25(OH)D concentrations (+21.5 ± 13.4 ng/mL) but not insulin secretion rates (primary outcome of the parent study) as reported previously. In this ancillary study there was no significant effect of vitamin D3 supplementation on serum cholesterol profile or surrogate biomarkers of cholesterol absorption and endogenous synthesis. Compared with participants not treated with cholesterol-lowering medications, those who were treated exhibited a greater reduction in plasma campesterol concentrations in the vitamin D3 but not placebo group (P-interaction = 0.011). Analyzing the data on the basis of cholesterol absorption status (hypo- versus hyperabsorbers) or cholesterol synthesis status (hypo- versus hypersynthesizers) did not alter these results.

CONCLUSIONS

Vitamin D3 supplementation for 24 wk had no significant effect on surrogate biomarkers of cholesterol absorption or endogenous synthesis, consistent with the lack of effect on serum cholesterol profile. Vitamin D3 supplementation resulted in greater reduction in campesterol concentrations in participants not using compared with those using cholesterol-lowering medications. Further studies are required.This trial was registered at clinicaltrials.gov as NCT01736865.

Plasma Non-cholesterol Sterols as Markers of Cholesterol Synthesis and Intestinal Absorption: A Critical Review

Plasma concentrations of phytosterols and non-cholesterol sterol precursors of cholesterol synthesis have been used as markers of intestinal cholesterol absorption and synthesis in inherited and secondary dyslipidemias and in population-based investigations to evaluate the risk for cardiovascular disease, respectively. The method aims at replacing initial research procedures such as the use of stable isotopes associated with fecal steroid balance, which are limited by the high cost and tedious procedures. However, we show in this review that numerous results obtained with serum sterol measurements are contradictory. In this regard, the following points are discussed: 1) how phytosterols relate to atherosclerosis considering that defects in biliary output or in the transport of phytosterols from the intestinal mucosa back into the intestinal lumen provide increased content of phytosterols and other sterols in plasma and tissues, thus not allowing to conclude that their presence in arteries and atheromas represents the etiology of atherosclerosis; 2) serum non-cholesterol sterols as markers of cholesterol synthesis and absorption, such as cholestanol, present discrepant results, rendering them often inadequate to identify cases of coronary artery disease as well as alterations in the whole body cholesterol metabolism; 3) such methods of measurement of cholesterol metabolism are confounded by factors like diabetes mellitus, body weight and other pathologies including considerable hereditary hyperlipidemias biological variabilities that influence the efficiency of synthesis and intestinal absorption of cholesterol.

The coronary artery calcium score is linked to plasma cholesterol synthesis and absorption markers: Brazilian Longitudinal Study of Adult Health

It is controversial whether atherosclerosis is linked to increased intestinal cholesterol absorption or synthesis in humans. The aim of the present study was to relate atherosclerosis to the measurements of plasma markers of cholesterol synthesis (desmosterol, lathosterol) and absorption (campesterol, sitosterol). In healthy male (n=344), non-obese, non-diabetics, belonging to the city of São Paulo branch of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil), we measured in plasma these non-cholesterol sterol markers, together with their anthropometric, dietary parameters, traditional atherosclerotic risk factors, and blood chemistry, coronary arterial calcium score (CAC), and ultrasonographically measured common carotid artery intima-media thickness (CCA-IMT). Cases with CAC>zero had the following parameters higher than cases with CAC = zero: age, waist circumference (WC), plasma total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and non-high density lipoprotein-cholesterol (non HDL-C). Plasma desmosterol and campesterol, duly corrected for TC, age, body mass index (BMI), waist circumference (WC), hypertension, smoking, and the homeostasis model assessment-insulin resistance (HOMA-IR) correlated with CAC, but not with CCA-IMT. The latter related to increased age, BMI, waist circumference (WC), and systolic blood pressure (SBP). Plasma HDL-C concentrations did not define CAC or CCA-IMT degrees, although in relation to the lower tertile of HDL-C in plasma the higher tertile of HDL-C had lower HOMA-IR and concentration of a cholesterol synthesis marker (desmosterol). Present work indicated that increased cholesterol synthesis and absorption represent primary causes of CAD, but not of the common carotid artery atherosclerosis.

Unraveling Host-Gut Microbiota Dialogue and Its Impact on Cholesterol Levels

Disruption in cholesterol metabolism, particularly hypercholesterolemia, is a significant cause of atherosclerotic cardiovascular disease. Large interindividual variations in plasma cholesterol levels are traditionally related to genetic factors, and the remaining portion of their variance is accredited to environmental factors. In recent years, the essential role played by intestinal microbiota in human health and diseases has emerged. The gut microbiota is currently viewed as a fundamental regulator of host metabolism and of innate and adaptive immunity. Its bacterial composition but also the synthesis of multiple molecules resulting from bacterial metabolism vary according to diet, antibiotics, drugs used, and exposure to pollutants and infectious agents. Microbiota modifications induced by recent changes in the human environment thus seem to be a major factor in the current epidemic of metabolic/inflammatory diseases (diabetes mellitus, liver diseases, inflammatory bowel disease, obesity, and dyslipidemia). Epidemiological and preclinical studies report associations between bacterial communities and cholesterolemia. However, such an association remains poorly investigated and characterized. The objectives of this review are to present the current knowledge on and potential mechanisms underlying the host-microbiota dialogue for a better understanding of the contribution of microbial communities to the regulation of cholesterol homeostasis.

Endothelial Nitric Oxide Mediates the Anti-Atherosclerotic Action of Torenia concolor Lindley var. Formosama Yamazaki

Torenia concolor Lindley var. formosama Yamazaki ethanolic extract (TCEE) is reported to have anti-inflammatory and anti-obesity properties. However, the effects of TCEE and its underlying mechanisms in the activation of endothelial nitric oxide synthase (eNOS) have not yet been investigated. Increasing the endothelium-derived nitric oxide (NO) production has been known to be beneficial against the development of cardiovascular diseases. In this study, we investigated the effect of TCEE on eNOS activation and NO-related endothelial function and inflammation by using an in vitro system. In endothelial cells (ECs), TCEE increased NO production in a concentration-dependent manner without affecting the expression of eNOS. In addition, TCEE increased the phosphorylation of eNOS at serine 635 residue (Ser635) and Ser1179, Akt at Ser473, calmodulin kinase II (CaMKII) at threonine residue 286 (Thr286), and AMP-activated protein kinase (AMPK) at Thr172. Moreover, TCEE-induced NO production, and EC proliferation, migration, and tube formation were diminished by pretreatment with LY294002 (an Akt inhibitor), KN62 (a CaMKII inhibitor), and compound C (an AMPK inhibitor). Additionally, TCEE attenuated the tumor necrosis factor-α-induced inflammatory response as evidenced by the expression of adhesion molecules in ECs and monocyte adhesion onto ECs. These inflammatory effects of TCEE were abolished by L-NG-nitroarginine methyl ester (an NOS inhibitor). Moreover, chronic treatment with TCEE attenuated hyperlipidemia, systemic and aortic inflammatory response, and the atherosclerotic lesions in apolipoprotein E-deficient mice. Collectively, our findings suggest that TCEE may confer protection from atherosclerosis by preventing endothelial dysfunction.

Mortality and Cholesterol Metabolism in Subjects Aged 75 Years and Older: The Helsinki Businessmen Study

BACKGROUND/OBJECTIVES

In many studies, low serum cholesterol is paradoxically associated with a higher mortality risk among older adults. Therefore, we studied whole-body cholesterol metabolism and its role in all-cause mortality of older men in two subcohorts of different ages.

DESIGN

Prospective long-term cohort.

SETTING

Home-dwelling men of the Helsinki Businessmen Study.

PARTICIPANTS

Two partly overlapping subcohorts were recruited, in 2003 (n = 660; mean age = 76 years) and in 2011 (n = 398; mean age = 83 years). The younger subcohort was followed up after 3 and 11 years, and the older subcohort was followed up after 3 years.

MEASUREMENTS

Cholesterol metabolism was assessed via serum noncholesterol sterol-cholesterol ratios, and quantification was performed by gas-liquid chromatography with flame ionization detection. All statistical analyses were performed with age and statin treatment as covariates.

RESULTS

At the end of the 3-year follow-up, 10% of the younger and 13% of the older subcohort had died; and at the end of the 11-year follow-up, 40% of the younger subcohort had died. Serum total and low-density lipoprotein (LDL) cholesterol and cholesterol precursors reflecting cholesterol synthesis were lower in the older than in the younger subcohort (P < .001 for all). In the older subcohort, low serum campesterol and sitosterol, reflecting decreased cholesterol absorption efficiency, predicted all-cause mortality (P < .05). This was supported by a trend toward low serum campesterol and sitosterol predicting mortality (P = .088 and P = .079, respectively) in the younger subcohort after 11 years. Cholesterol synthesis did not predict mortality, but in the older subcohort, decreased cholesterol absorption was less efficiently compensated for by decreased cholesterol synthesis.

CONCLUSIONS

Low cholesterol absorption efficiency predicted all-cause mortality, especially in men aged 83 years on average, and cholesterol synthesis was lowered. These metabolic changes could contribute to the lowering of serum total and LDL-cholesterol in older men. J Am Geriatr Soc 68:281-287, 2020.

The intestinal microbiota regulates host cholesterol homeostasis

BACKGROUND

Management of blood cholesterol is a major focus of efforts to prevent cardiovascular diseases. The objective of this study was to investigate how the gut microbiota affects host cholesterol homeostasis at the organism scale.

RESULTS

We depleted the intestinal microbiota of hypercholesterolemic female Apoe^-/- mice using broad-spectrum antibiotics. Measurement of plasma cholesterol levels as well as cholesterol synthesis and fluxes by complementary approaches showed that the intestinal microbiota strongly regulates plasma cholesterol level, hepatic cholesterol synthesis, and enterohepatic circulation. Moreover, transplant of the microbiota from humans harboring elevated plasma cholesterol levels to recipient mice induced a phenotype of high plasma cholesterol levels in association with a low hepatic cholesterol synthesis and high intestinal absorption pattern. Recipient mice phenotypes correlated with several specific bacterial phylotypes affiliated to Betaproteobacteria, Alistipes, Bacteroides, and Barnesiella taxa.

CONCLUSIONS

These results indicate that the intestinal microbiota determines the circulating cholesterol level and may thus represent a novel therapeutic target in the management of dyslipidemia and cardiovascular diseases.

Progress and perspectives in plant sterol and plant stanol research

Current evidence indicates that foods with added plant sterols or stanols can lower serum levels of low-density lipoprotein cholesterol. This review summarizes the recent findings and deliberations of 31 experts in the field who participated in a scientific meeting in Winnipeg, Canada, on the health effects of plant sterols and stanols. Participants discussed issues including, but not limited to, the health benefits of plant sterols and stanols beyond cholesterol lowering, the role of plant sterols and stanols as adjuncts to diet and drugs, and the challenges involved in measuring plant sterols and stanols in biological samples. Variations in interindividual responses to plant sterols and stanols, as well as the personalization of lipid-lowering therapies, were addressed. Finally, the clinical aspects and treatment of sitosterolemia were reviewed. Although plant sterols and stanols continue to offer an efficacious and convenient dietary approach to cholesterol management, long-term clinical trials investigating the endpoints of cardiovascular disease are still lacking.

Plasma oxyphytosterol concentrations are not associated with CVD status in Framingham Offspring Study participants

Dietary plant sterols, such as campesterol and sitosterol, reduce plasma cholesterol concentrations, but any relationship to plaque development and CVD remains unclear. Some epidemiologic studies have suggested that elevated plasma plant sterol concentrations are atherogenic, including the Framingham Offspring Study that identified a positive association between plant sterol concentrations and CVD status. We hypothesized that this suggested atherogenicity relates to the oxidation status of plant sterols (i.e., concentrations of plasma oxyphytosterols). Therefore, in the Framingham Offspring Study cohort, we measured plasma oxyphytosterol concentrations in 144 patients with documented CVD and/or more than 50% carotid stenosis and 383 matched controls. We analyzed plasma oxyphytosterol concentrations by GC/MS/MS and performed conditional logistic regression analysis to determine associations between plasma plant sterol or oxyphytosterol concentrations and CVD status. We found that higher total cholesterol (TC)-standardized campesterol concentrations [odds ratio (OR): 2.36; 95% CI: 1.60, 3.50] and higher sitosterol concentrations (OR: 1.47; 95% CI: 1.09, 1.97) were significantly associated with increased CVD risk, as in the earlier study. However, the sum of absolute oxyphytosterol concentrations (OR: 0.99; 95% CI: 0.81, 1.21) and the sum of TC-standardized oxyphytosterol concentrations (OR: 0.98; 95% CI: 0.80, 1.19) were not associated with an increased CVD risk. Results were comparable for individual absolute and TC-standardized oxycampesterol and oxysitosterol concentrations. Plasma nonoxidized TC-standardized sitosterol and campesterol concentrations showed weak or no correlations with oxyphytosterol concentrations, while all individual plasma concentrations of oxyphytosterol correlated with each other. In conclusion, circulating plasma oxyphytosterols are not associated with CVD risk in the Framingham Offspring Study.

Low serum lathosterol levels associate with fatal cardiovascular disease and excess all-cause mortality: a prospective cohort study

IMPORTANCE

A more precise identification of patients at "high cardiovascular risk" is preeminent in cardiovascular risk stratification.

OBJECTIVE

To investigate the relationships between markers of cholesterol homeostasis, cardiovascular events and all-cause mortality.

DESIGN, SETTING AND PARTICIPANTS

We quantified markers of cholesterol homeostasis by gas chromatography-mass spectrometry in 377 subjects with suspected coronary artery disease, who were not on lipid-lowering drugs at baseline. All patients were followed for occurrence of cardiovascular events and mortality over a period of 4.9 +/- 1.7 years. The standardized mortality ratio (SMR) was calculated as the ratio of the observed and the expected deaths based on the death rates of the Regional Databases Germany, and Poisson regression (rate ratio, RR) was used to compare subgroups. The SMR and RR were standardized for sex, age category and calendar period. In addition, Cox regression (Hazard ratio, HR) was used to determine the effect of co-variables on (cardiovascular) mortality within the cohort.

MAIN OUTCOMES

Cardiovascular events, cardiovascular mortality and all-cause mortality.

RESULTS

A total of 42 deaths were observed in 1818 person-years corresponding with an SMR of 0.99 (95% CI 0.71-1.33; p = 0.556). A fatal cardiovascular event occurred in 26 patients. Lower levels of lathosterol were associated with increased cardiovascular mortality (HR 1.59; 95% CI: 1.16-2.17; p = 0.004) and excess all-cause mortality (HR 1.41; 95% CI: 1.09-1.85; p = 0.011). Lower lathosterol tertile compared to the adjacent higher tertile was associated with 1.6 times higher all-cause mortality risk (RR 1.60; 95% CI 1.07-2.40; p for trend = 0.022). This corresponded with a 2.3 times higher mortality risk of a lathosterol-LDL ratio equal to or below the median (RR 2.29; 95% CI 1.19-4.43; p = 0.013). None of the other cholesterol homeostasis markers were associated with cardiovascular and all-cause mortality.

CONCLUSIONS

In patients not on lipid-lowering agents, low serum lathosterol correlated with increased risk of cardiovascular events and excess all-cause mortality.

The emerging concept of "individualized cholesterol-lowering therapy": A change in paradigm

High LDL-cholesterol concentrations constitute a risk for atherosclerotic cardiovascular disease. By consensus, cholesterol-lowering therapy is initiated with a statin that reduces endogenous cholesterol synthesis, upregulates hepatic LDL receptor activity, increases LDL clearance and lowers LDL-cholesterol concentrations in the bloodstream. The efficacy of statin treatment is dose dependent and achieves a risk reduction of up to 50%. However, a substantial body of evidence suggests that a quarter of statin-treated patients do not respond adequately as a result of low endogenous cholesterol synthesis. In humans fractional cholesterol absorption varies from 20% to 80%. High cholesterol absorbers, which are characterized by a low-to-normal cholesterol synthesis, exhibit poor responsiveness to statin treatment. On the other hand, the cholesterol absorption inhibitor ezetimibe effectively reduces serum cholesterol levels in these patients. On this background, we suggest to "get personal" and individualize cholesterol-lowering therapies, according to the individual's status of cholesterol synthesis and absorption.

Plant-based sterols and stanols in health & disease: "Consequences of human development in a plant-based environment?"

Dietary plant sterols and stanols as present in our diet and in functional foods are well-known for their inhibitory effects on intestinal cholesterol absorption, which translates into lower low-density lipoprotein cholesterol concentrations. However, emerging evidence suggests that plant sterols and stanols have numerous additional health effects, which are largely unnoticed in the current scientific literature. Therefore, in this review we pose the intriguing question "What would have occurred if plant sterols and stanols had been discovered and embraced by disciplines such as immunology, hepatology, pulmonology or gastroenterology before being positioned as cholesterol-lowering molecules?" What would then have been the main benefits and fields of application of plant sterols and stanols today? We here discuss potential effects ranging from its presence and function intrauterine and in breast milk towards a potential role in the development of non-alcoholic steatohepatitis (NASH), cardiovascular disease (CVD), inflammatory bowel diseases (IBD) and allergic asthma. Interestingly, effects clearly depend on the route of entrance as observed in intestinal-failure associated liver disease (IFALD) during parenteral nutrition regimens. It is only until recently that effects beyond lowering of cholesterol concentrations are being explored systematically. Thus, there is a clear need to understand the full health effects of plant sterols and stanols.

Non-Cholesterol Sterol Concentrations as Biomarkers for Cholesterol Absorption and Synthesis in Different Metabolic Disorders: A Systematic Review

Non-cholesterol sterols are validated biomarkers for intestinal cholesterol absorption and endogenous cholesterol synthesis. However, their use in metabolic disturbances has not been systematically explored. Therefore, we conducted a systematic review to provide an overview of non-cholesterol sterols as markers for cholesterol metabolism in different metabolic disorders. Potentially relevant studies were retrieved by a systematic search of three databases in July 2018 and ninety-four human studies were included. Cholesterol-standardized levels of campesterol, sitosterol and cholestanol were collected to reflect cholesterol absorption and those of lathosterol and desmosterol to reflect cholesterol synthesis. Their use as biomarkers was examined in the following metabolic disorders: overweight/obesity (n = 16), diabetes mellitus (n = 15), metabolic syndrome (n = 5), hyperlipidemia (n = 11), cardiovascular disease (n = 17), and diseases related to intestine (n = 16), liver (n = 22) or kidney (n = 2). In general, markers for cholesterol absorption and synthesis displayed reciprocal patterns, showing that cholesterol metabolism is tightly regulated by the interplay of intestinal absorption and endogenous synthesis. Distinctive patterns for cholesterol absorption or cholesterol synthesis could be identified, suggesting that metabolic disorders can be classified as 'cholesterol absorbers or cholesterol synthesizers'. Future studies should be performed to confirm or refute these findings and to examine whether this information can be used for targeted (dietary) interventions.

The interrelations between PCSK9 metabolism and cholesterol synthesis and absorption

Very few studies have investigated the interrelations between proprotein convertase subtilisin/kexin type 9 (PCSK9) metabolism, cholesterol synthesis, and cholesterol absorption. We aimed to address this issue in a large clinical trial of 245 patients with hypercholesterolemia. Serum lipids, PCSK9, lathosterol (cholesterol synthesis marker), campesterol, and sitosterol (cholesterol absorption markers) were measured before and 4-8 weeks after the start of treatment with PCSK9-antibodies (alirocumab or evolocumab). The patients had mean (standard error) LDL-cholesterol and PCSK9 concentrations of 3.87 (0.10) mmol/l and 356 (17) ng/ml, respectively. Eighty-four patients received no lipid-lowering pretreatment, 26 ezetimibe, 38 statins, and 97 ezetimibe + statins. Circulating PCSK9 increased in parallel with the potency of lipid-lowering pretreatment with circulating PCSK9 being highest in the ezetimibe + statin group (P < 0.001). Treatment with PCSK9-antibodies strongly decreased LDL-cholesterol, lathosterol, campesterol, and sitosterol (all P < 0.001) but hardly affected noncholesterol sterol to cholesterol ratios. Lipid-lowering pretreatment was not associated with the effects of PCSK9-antibodies on noncholesterol sterols (all P > 0.05). Summing up, circulating PCSK9 is increased by cholesterol synthesis and absorption inhibitors. Increased PCSK9 expression may partly explain the strong reductions of LDL-cholesterol achieved with PCSK9-antibodies after such pretreatment. On the other hand, treatment with PCSK9-antibodies does not significantly change the balance between cholesterol synthesis and absorption.

Potential role of phytochemicals in metabolic syndrome prevention and therapy

Metabolic syndrome (MetS) is a set of cardiovascular risk factors which severely increases the risk of type II diabetes, renal disease and cardiovascular disease. Over the last decades, the role of dietary bioactive substances in features of MetS has been extensively investigated. Due to their multiple properties, these plant-derived natural compounds have demonstrated to provide positive effects in obesity, diabetes, renal and in cardiovascular disease. Catechins of green tea and caffeine reduce body mass index and waist circumference. Catechins, anthocyanins and proanthocyanidins of cocoa reduce blood pressure and blood glucose. Curcumin and silymarin exert hepatoprotective effects. Monacolins of red yeast rice are effective cholesterol-lowering agents. However, inconsistent or conflicting results have been found in clinical trials when other promising compounds in vitro or in animal studies, such as policosanol, curcumin or silymarin, were used. Low oral bioavailability of substances, ineffective dosages, inadequate treatment duration and insufficient statistical approach may explain the lack of effectiveness observed in some human studies. Further clinical studies are needed to better understand the role of bioactive compounds in the prevention and management of MetS.

First Report of Plant-Derived β-Sitosterol with Antithrombotic, in Vivo Anticoagulant, and Thrombus-Preventing Activities in a Mouse Model

Inhibitors of thrombin, a key enzyme in the blood coagulation cascade, are of great interest because of their selective specificity and effectiveness in anticoagulation therapy against cardiovascular disorders. The natural soybean phytosterol, β-sitosterol (BSS) demonstrated anticoagulant activity by dose-dependent inhibition of thrombin in an uncompetitive manner with a K_i value of 0.267 μM as well as by partial inhibition of thrombin-catalyzed platelet aggregation with a half-maximal inhibitory concentration (IC₅₀) value of 10.45 ± 2.88 μM against platelet-rich plasma and 9.2 ± 1.2 μM against washed platelets. An in silico study indicated binding of BSS to thrombin, which was experimentally verified by spectrofluorometric and isothermal calorimetric analyses. Under in vitro conditions, BSS demonstrated thrombolytic activity by activating plasminogen, albeit it is devoid of protease (fibrinogenolytic) activity. BSS was noncytotoxic to mammalian cells, nonhemolytic, demonstrated its in vivo anticoagulant activity when administered orally, and inhibited k-carrageen-induced thrombus formation in the tails of mice. Our results suggest that dietary supplementation of BSS may help to prevent thrombosis-associated cardiovascular disorders.

Recurrent tendosynovitis as a rare manifestation of a lipid disorder

A 33-year-old female had suffered from spontaneously recurrent bursitis and tendosynovitis/enthesitis of the patellar and Achilles tendons for about 10 years. The episodes of immobilization increased. Ultrasound imaging of the swollen and painful tendons showed chronic inflammation with neoangiogenesis within the tendons and hypoechoic lesions. Clinical and laboratory tests did not provide evidence for a rheumatic disease. Low density lipoprotein cholesterol was elevated. Biopsies of skin lesions did not confirm the suspicion of cutaneous xanthomas. Genetic testing for familial hypercholesterolemia was negative. Campesterol and sitosterol were elevated 7- to 12-fold and 20- to 38-fold over the upper limit of normal on two occasions. There was no relevant mutation in ABCG5. In ABCG8, we identified a missense mutation c.1267G>A in exon 9 changing glutamic acid 423 into lysine within the transmembrane domain, and an insertion of adenine (c.1487insA) leading to a frameshift and a premature stop codon (Ile497Aspfs*105). The patient had no clinical evidence of premature atherosclerosis. Therapeutic approaches with nonsteroidal antirheumatic drugs, prednisone, statins, and ezetimibe accompanied by a diet poor in plant sterols led to a relief of symptoms. This case report shows that tendon xanthoma along with tendosynovitis, especially on extensor areas, is suspicious for hypercholesterolemia as the underlying cause. The absence of atherosclerotic plaques in the abdominal aorta and in the carotid arteries on ultrasound may suggest that phytosterolemia is not necessarily accompanied by premature vascular disease.

Plasma levels of the oxyphytosterol 7α-hydroxycampesterol are associated with cardiovascular events

BACKGROUND AND AIMS

There are safety issues regarding plant sterol ester-enriched functional food. Oxidized plant sterols, also called oxyphytosterols, are supposed to contribute to plant sterol atherogenicity. This study aimed to analyze associations of plasma oxyphytosterol levels with cardiovascular events.

METHODS

Plasma cholesterol was measured by gas chromatography-flame ionization detection. Plasma campesterol and sitosterol and their 7-oxygenated metabolites were analyzed by gas chromatography-mass selective detection.

RESULTS

In 376 patients admitted for elective coronary angiography, who were not on lipid-lowering drugs, 82 cardiovascular events occurred during a follow-up period of 4.2 ± 1.8 years. Patients with cardiovascular events had significantly higher 7α-hydroxycampesterol plasma levels (median, 0.46; [interquartile range (IQR) 0.22-0.81] nmol/L vs. median, 0.25 [IQR, 0.17-0.61] nmol/L; p = 0.003) and 7α-hydroxycampesterol-to-cholesterol ratios (median 0.08 [IQR, 0.04-0.14] nmol/mmol vs. median, 0.05 [IQR 0.03-0.11] nmol/mmol; p = 0.005) than controls without such events. Patients above the median were characterized by higher cumulative event rates in Kaplan-Meier-analysis (Logrank-test p = 0.084 and p = 0.025) for absolute and cholesterol corrected 7α-hydroxycampesterol, respectively. After adjustment for influencing factors and related lipids, the hazard ratios per one standard deviation of the log-transformed variables (HR) were 1.19 [95% confidence interval (CI), 0.95-1.48], p = 0.132 for 7α-hydroxycampesterol and HR, 1.18 [95% CI, 0.94-1.48], p = 0.154 for 7α-hydroxycampesterol-to-cholesterol ratio. None of the other investigated oxyphytosterols showed an association with cardiovascular events.

CONCLUSIONS

In patients not on lipid-lowering drugs, absolute plasma levels of 7α-hydroxycampesterol and their ratios to cholesterol are associated with cardiovascular events. Further research is required to elucidate the role of OPS in cardiovascular diseases.

Plant sterol enriched functional food and atherosclerosis

Hypercholesterolaemia is a major cardiovascular risk factor. A healthy diet and a healthy lifestyle reduces cardiovascular risk. 'Functional foods' supplemented with phytosterols are recommended for the management of hypercholesterolaemia and have become a widely used non-prescription approach to lower plasma cholesterol levels. Two billion euros are spent world-wide each year on various functional foods, which have regulator-approved health claims for the management of elevated cholesterol levels. While international societies, such as the European Atherosclerosis Society or the National Heart Foundation in Australia, still advise phytosterols as an additional dietary option in the management of hypercholesterolaemia, recently released guidelines such as those from the National Institute of Health and Clinical Excellence in the United Kingdom are more critical of food supplementation with phytosterols and draw attention to significant safety issues. This review challenges whether an intervention with phytosterol supplements is beneficial. We summarize the current evidence from genetic diseases, genetic association studies, clinical trial data and data from animal studies.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Individualized lipid-lowering therapy to further reduce residual cardiovascular risk

Hypercholesterolemia is a major risk factor for cardiovascular diseases. Serum cholesterol concentrations are regulated by enteral absorption, biliary secretion, and hepatic synthesis. Statins inhibit the rate-limiting enzyme of cholesterol synthesis, HMG-CoA-reductase, and reduce serum cholesterol concentrations as well as cardiovascular morbidity and mortality. Some studies indicate that patients with high baseline cholesterol absorption may show only a small response to statin treatment in terms of cholesterol lowering. Data from genetic association studies and from the IMPROVE-IT trial show that reducing intestinal cholesterol absorption via NCP1L1 further reduces cardiovascular risk. However, some patients do not attain LDL-cholesterol targets on combination therapy. For these patients PCSK9-antibody treatment and lipid-apheresis are options to be considered. This article reviews the current literature on this issue and suggests 'individualized lipid-lowering therapy' as an approach to optimize and personalize lipid-lowering treatment of patients with hypercholesterolemia to further reduce residual cardiovascular risk.

Can non-cholesterol sterols and lipoprotein subclasses distribution predict different patterns of cholesterol metabolism and statin therapy response?

BACKGROUND

Cholesterol homeostasis disorders may cause dyslipidemia, atherosclerosis progression and coronary artery disease (CAD) development. Evaluation of non-cholesterol sterols (NCSs) as synthesis and absorption markers, and lipoprotein particles quality may indicate the dyslipidemia early development. This study investigates associations of different cholesterol homeostasis patterns with low-density (LDL) and high-density lipoproteins (HDL) subclasses distribution in statin-treated and statin-untreated CAD patients, and potential use of aforementioned markers for CAD treatment optimization.

METHODS

The study included 78 CAD patients (47 statin-untreated and 31 statin-treated) and 31 controls (CG). NCSs concentrations were quantified using gas chromatography- flame ionization detection (GC-FID). Lipoprotein subclasses were separated by gradient gel electrophoresis.

RESULTS

In patients, cholesterol-synthesis markers were significantly higher comparing to CG. Cholesterol-synthesis markers were inversely associated with LDL size in all groups. For cholesterol homeostasis estimation, each group was divided to good and/or poor synthetizers and/or absorbers according to desmosterol and β-sitosterol median values. In CG, participants with reduced cholesterol absorption, the relative proportion of small, dense LDL was higher in those with increased cholesterol synthesis compared to those with reduced synthesis (p<0.01). LDL I fraction was significantly higher in poor synthetizers/poor absorbers subgroup compared to poor synthetizers/good absorbers (p<0.01), and good synthetizers/poor absorbers (p<0.01). Statin-treated patients with increased cholesterol absorption had increased proportion of LDL IVB (p<0.05).

CONCLUSIONS

The results suggest the existence of different lipoprotein abnormalities according to various patterns of cholesterol homeostasis. Desmosterol/β-sitosterol ratio could be used for estimating individual propensity toward dyslipidemia development and direct the future treatment.

Ezetimibe in Combination With Statins Ameliorates Endothelial Dysfunction in Coronary Arteries After Stenting

Objectives—

We sought to investigate whether treatment with ezetimibe in combination with statins improves coronary endothelial function in target vessels in coronary artery disease patients after coronary stenting.

Approach and Results—

We conducted a multicenter, prospective, randomized, open-label, blinded-end point trial among 11 cardiovascular treatment centers. From 2011 to 2013, 260 coronary artery disease patients who underwent coronary stenting were randomly allocated to 2 arms (statin monotherapy, S versus ezetimibe [10 mg/d]+statin combinational therapy, E+S). We defined target vessel dysfunction as the primary composite outcome, which comprised target vessel failure during treatment and at the 6- to 8-month follow-up coronary angiography and coronary endothelial dysfunction determined via intracoronary acetylcholine testing performed in cases without target vessel failure at the follow-up coronary angiography. Coadministration of ezetimibe with statins further lowered low-density lipoprotein cholesterol levels (83±23 mg/dL in S versus 67±23 mg/dL in E+S; P <0.0001), with significant decreases in oxidized low-density lipoprotein and oxysterol levels. Among patients without target vessel failure, 46 out of 89 patients (52%) in the S arm and 34 out of 96 patients (35%) in the E+S arm were found to have coronary endothelial dysfunction ( P =0.0256), and the incidence of target vessel dysfunction at follow-up was significantly decreased in the E+S arm (69/112 (62%) in S versus 47/109 (43%) in E+S; P =0.0059). A post hoc analysis of post-treatment low-density lipoprotein cholesterol–matched subgroups revealed that the incidence of both target vessel dysfunction and coronary endothelial dysfunction significantly decreased in the E+S arm, with significant reductions in oxysterol levels.

Conclusions—

The CuVIC trial (Effect of Cholesterol Absorption Inhibitor Usage on Target Vessel Dysfunction after Coronary Stenting) has shown that ezetimibe with statins, compared with statin monotherapy, improves functional prognoses, ameliorating endothelial dysfunction in stented coronary arteries, and was associated with larger decreases in oxysterol levels.

Lipid-modifying effects of nutraceuticals: An evidence-based approach

The present review provides an up-to-date summary of the findings on the lipid-lowering effects of the most important nutraceuticals and functional foods. Based on current knowledge, nutraceuticals might exert significant lipid-lowering, and their use has several advantages: A number of important questions remain to be addressed, including whether longer durations of therapy would result in a better response and the exact safety profile of nutraceuticals, especially at doses higher than those consumed in an average diet. Additionally, data regarding the effects of nutraceutical supplementation on the incidence of cardiovascular outcomes are lacking, and it is not clear whether additional lipid lowering by nutraceuticals can modify the residual cardiovascular risk that remains after statin therapy.

Cholesterol absorption and synthesis markers in Portuguese hypercholesterolemic adults: A cross-sectional study

OBJECTIVE

The dynamics of cholesterol homeostasis and the development of cardiovascular disease (CVD) are complex and multifactorial, to which adds individual variability in the proportion of cholesterol from exogenous versus endogenous sources. The aim of this study was to undertake the first characterization of cholesterol absorption and synthesis profiles in Portuguese hypercholesterolemic adults through the quantification of surrogate markers, and the analysis of the predictive value of age and sex on the cholesterol homeostasis biomarkers.

METHODS

Serum samples for the measurement of lipid profiles and cholesterol homeostasis markers were obtained for 100 men and 112 women, aged 30-65, with TC ≥ 5.2 mmol/L (~200mg/dL) and/or LDL-C ≥ 2.6 mmol/L (~100mg/dL), none of whom were on any lipid-lowering therapy.

RESULTS

Overall, sex-specific significant differences were observed in the cholesterol homeostasis markers and lipid profiles; women had lower cholesterol synthesis marker concentrations (P<0.01 for lathosterol) and lipid parameters (except for HDL-C concentrations). Age-related significant differences were also found, including higher concentrations of cholesterol absorption markers in association with increasing age.

CONCLUSION

In our study, the predictors of higher levels of cholesterol absorption markers were higher age and female gender.

Aberrant de novo cholesterogenesis: Clinical significance and implications

Human cells can acquire cholesterol from the circulation but also have the ability to synthesize it via de novo cholesterogenesis (DC). Cholesterol absorption and de novo cholesterogenesis are the key processes that modulate cholesterol homeostasis in the human body. The endogenous biosynthesis of cholesterol substantially contributes to the whole-body cholesterol pool. Additionally, dysregulation of this pathway is associated with diverse medical conditions. The present review focuses on our current understanding of the cholesterogenic pathway and the various different factors regulating this pathway. It also highlights dysregulation of this pathway in various physiological and pathological conditions including cardiovascular diseases, type II diabetes, obesity and viral infections.

Increased plant sterol deposition in vascular tissue characterizes patients with severe aortic stenosis and concomitant coronary artery disease

The aim of the study was to evaluate the relationship between phytosterols, oxyphytosterols, and other markers of cholesterol metabolism and concomitant coronary artery disease (CAD) in patients with severe aortic stenosis who were scheduled for elective aortic valve replacement. Markers of cholesterol metabolism (plant sterols and cholestanol as markers of cholesterol absorption and lathosterol as an indicator of cholesterol synthesis) and oxyphytosterols were determined in plasma and aortic valve tissue from 104 consecutive patients with severe aortic stenosis (n=68 statin treatment; n=36 no statin treatment) using gas chromatography-flame ionization and mass spectrometry. The extent of CAD was determined by coronary angiography prior to aortic valve replacement. Patients treated with statins were characterized by lower plasma cholesterol, cholestanol, and lathosterol concentrations. However, statin treatment did not affect the sterol concentrations in cardiovascular tissue. The ratio of campesterol-to-cholesterol was increased by 0.46±0.34μg/mg (26.0%) in plasma of patients with CAD. The absolute values for the cholesterol absorption markers sitosterol and campesterol were increased by 18.18±11.59ng/mg (38.8%) and 11.40±8.69ng/mg (30.4%) in the tissues from patients with documented CAD compared to those without concomitant CAD. Campesterol oxides were increased by 0.06±0.02ng/mg (17.1%) in the aortic valve cusps and oxidized sitosterol-to-cholesterol ratios were up-regulated by 0.35±0.2ng/mg (22.7%) in the plasma of patients with CAD. Of note, neither cholestanol nor the ratio of cholestanol-to-cholesterol was associated with CAD. Patients with concomitant CAD are characterized by increased deposition of plant sterols, but not cholestanol in aortic valve tissue. Moreover, patients with concomitant CAD were characterized by increased oxyphytosterol concentrations in plasma and aortic valve cusps.

Potential risks associated with increased plasma plant-sterol levels

The consumption of plant sterols is associated with a decrease in LDL cholesterol. However, it is also associated with an increase in plasma plant-sterol (sitosterol, campesterol) levels that may be detrimental. Indeed, the genetic disease sitosterolaemia, which is characterized by elevated plasma levels of plant sterol, is associated with premature atherosclerosis. Yet, although plasma plant-sterol levels are recognized markers of cholesterol absorption, the relationship between such levels and atherosclerosis is not clear. Several studies have analysed the association between plasma plant-sterol levels and cardiovascular disease (CVD), but have found conflicting results. Although the largest prospective trials and genome-wide association studies suggest that high plasma levels of plant sterols are associated with increased CV risk, other studies have reported no such association and even an inverse relationship. Thus, the available data cannot confirm an increased CV risk with plant sterols, but cannot rule it out either. Only a prospective interventional trial to analyse the effects of plant-sterol-enriched food on the occurrence of CV events can exclude a potential CV risk linked with their consumption.

Longitudinal trajectories of cholesterol from midlife through late life according to apolipoprotein E allele status

BACKGROUND

Previous research indicates that total cholesterol levels increase with age during young adulthood and middle age and decline with age later in life. This is attributed to changes in diet, body composition, medication use, physical activity, and hormone levels. In the current study we utilized data from the Framingham Heart Study Original Cohort to determine if variations in apolipoprotein E (APOE), a gene involved in regulating cholesterol homeostasis, influence trajectories of total cholesterol, HDL cholesterol, and total: HDL cholesterol ratio from midlife through late life.

METHODS

Cholesterol trajectories from midlife through late life were modeled using generalized additive mixed models and mixed-effects regression models.

RESULTS

APOE e2+ subjects had lower total cholesterol levels, higher HDL cholesterol levels, and lower total: HDL cholesterol ratios from midlife to late life compared to APOE e3 and APOE e4+ subjects. Statistically significant differences in life span cholesterol trajectories according to gender and use of cholesterol-lowering medications were also detected.

CONCLUSION

The findings from this research provide evidence that variations in APOE modify trajectories of serum cholesterol from midlife to late life. In order to efficiently modify cholesterol through the life span, it is important to take into account APOE allele status.

Consuming a buttermilk drink containing lutein-enriched egg yolk daily for 1 year increased plasma lutein but did not affect serum lipid or lipoprotein concentrations in adults with early signs of age-related macular degeneration

Dietary lutein intake is postulated to interfere with the development of age-related macular degeneration (AMD). Because egg yolk-derived lutein has a high bioavailability, long-term consumption of lutein-enriched eggs might be effective in preventing AMD development, but alternatively might increase cardiovascular disease risk. Here, we report the effect of 1-y daily consumption of a buttermilk drink containing 1.5 lutein-rich egg yolks on serum lipid and lipoprotein and plasma lutein concentrations. Additionally, subgroups that could potentially benefit the most from the intervention were identified. Men and women who had early signs of AMD in at least 1 eye, but were otherwise healthy, participated in a 1-y randomized, placebo-controlled parallel intervention trial. At the start of the study, 101 participants were included: 52 in the experimental (Egg) group and 49 in the control (Con) group. Final analyses were performed with 45 participants in the Egg group and 43 participants in the Con group. As expected, the increase in plasma lutein concentrations in the Egg group was 83% higher than that in the Con group (P < 0.001). Changes in serum total, HDL, and LDL cholesterol, as well as the ratio of total cholesterol to HDL cholesterol, were not different between the 2 groups. Interestingly, participants classified as cholesterol absorbers had higher serum HDL cholesterol concentrations than participants classified as cholesterol synthesizers or participants with average campesterol-to-lathosterol ratios (P < 0.05) at baseline. In addition, cholesterol absorbers had a 229% higher increase in plasma lutein concentrations than participants who were classified as having an average campesterol-to-lathosterol ratio upon consumption of the lutein-enriched egg yolk drink (P < 0.05). Moreover, the change in serum HDL cholesterol upon consumption was significantly different between these 3 groups (P < 0.05). We suggest that cholesterol absorbers particularly might benefit from the lutein-enriched buttermilk drink. This study was registered at clinicaltrials.gov as NCT00902408.

Genomics of post-prandial lipidomic phenotypes in the Genetics of Lipid lowering Drugs and Diet Network (GOLDN) study

BACKGROUND

Increased postprandial lipid (PPL) response to dietary fat intake is a heritable risk factor for cardiovascular disease (CVD). Variability in postprandial lipids results from the complex interplay of dietary and genetic factors. We hypothesized that detailed lipid profiles (eg, sterols and fatty acids) may help elucidate specific genetic and dietary pathways contributing to the PPL response.

METHODS AND RESULTS

We used gas chromatography mass spectrometry to quantify the change in plasma concentration of 35 fatty acids and 11 sterols between fasting and 3.5 hours after the consumption of a high-fat meal (PPL challenge) among 40 participants from the GOLDN study. Correlations between sterols, fatty acids and clinical measures were calculated. Mixed linear regression was used to evaluate associations between lipidomic profiles and genomic markers including single nucleotide polymorphisms (SNPs) and methylation markers derived from the Affymetrix 6.0 array and the Illumina Methyl450 array, respectively. After the PPL challenge, fatty acids increased as well as sterols associated with cholesterol absorption, while sterols associated with cholesterol synthesis decreased. PPL saturated fatty acids strongly correlated with triglycerides, very low-density lipoprotein, and chylomicrons. Two SNPs (rs12247017 and rs12240292) in the sorbin and SH3 domain containing 1 (SORBS1) gene were associated with b-Sitosterol after correction for multiple testing (P≤4.5*10(-10)). SORBS1 has been linked to obesity and insulin signaling. No other markers reached the genome-wide significance threshold, yet several other biologically relevant loci are highlighted (eg, PRIC285, a co-activator of PPARa).

CONCLUSIONS

Integration of lipidomic and genomic data has the potential to identify new biomarkers of CVD risk.

Clinical utility of serum markers of cholesterol absorption and synthesis

PURPOSE OF REVIEW

The serum noncholesterol sterols are widely used today in clinical lipid research as surrogate markers of cholesterol absorption and synthesis. Their applicability and some aspects related to their analysis, use, and interpretations are discussed.

RECENT FINDINGS

The serum markers of cholesterol metabolism have been carefully validated in several populations and during different interventions. If the homeostasis between cholesterol absorption and synthesis is lost, the markers cannot be used as surrogates. The markers have been applied in large population and cohort studies to find out how cholesterol metabolism is related to coronary artery disease. Most of the large studies suggested that increased levels of the markers of cholesterol absorption may conceivably be a risk factor for coronary artery disease.

SUMMARY

Results even from large population studies vary from population to population. The large number of factors, which interfere with cholesterol metabolism, such as age, sex, BMI, diet, health status, medication, and genetic background, and differences in the analysis methods of the serum markers should be taken into consideration when interpreting the data.