Effect of statins on noncholesterol sterol levels: implications for use of plant stanols and sterols

Cholesterol-Lowering Bioactive Foods and Nutraceuticals in Pediatrics: Clinical Evidence of Efficacy and Safety

Long-term exposure to even slightly elevated plasma cholesterol levels significantly increases the risk of developing cardiovascular disease. The latest evidence recommends an improvement in plasma lipid levels, even in children who are not affected by severe hypercholesterolemia. The risk-benefit profile of pharmacological treatments in pediatric patients with moderate dyslipidemia is uncertain, and several cholesterol-lowering nutraceuticals have been recently tested. In this context, the available randomized clinical trials are small, short-term and mainly tested different types of fibers, plant sterols/stanols, standardized extracts of red yeast rice, polyunsaturated fatty acids, soy derivatives, and some probiotics. In children with dyslipidemia, nutraceuticals can improve lipid profile in the context of an adequate, well-balanced diet combined with regular physical activity. Of course, they should not be considered an alternative to conventional lipid-lowering drugs when necessary.

Association of Serum Oxysterols with Cholesterol Metabolism Markers and Clinical Factors in Patients with Coronary Artery Disease: A Covariance Structure Analysis

Oxysterols have been implicated in the pathogenesis of cardiovascular diseases. Serum levels of oxysterols could be positively correlated with cholesterol absorption and synthesis. However, physiological regulation of various serum oxysterols is largely unknown. The aim of this study was to investigate the relationship between clinical factors and cholesterol metabolism markers, and identify oxysterols associated with cholesterol absorption and synthesis in patients with coronary artery disease. Subjects (n = 207) who underwent coronary stenting between 2011 and 2013 were studied cross-sectionally. We measured lipid profiles including serum oxysterols. As for the serum biomarkers of cholesterol synthesis and absorption, oxysterol levels were positively correlated with campesterol and lathosterol. Covariance structure analysis revealed that dyslipidemia and statin usage had a positive correlation with "cholesterol absorption". Statin usage also had a positive correlation with "cholesterol synthesis". Several oxysterols associated with cholesterol absorption and/or synthesis. In conclusion, we elucidated the potential clinical factors that may affect cholesterol metabolism, and the associations between various oxysterols with cholesterol absorption and/or synthesis in patients with coronary artery disease.

Gas Chromatography and Flame-Ionization Detection of Non-Cholesterol Sterols as Indicators of Cholesterol Absorption and Synthesis in 158 Chinese Individuals with Normolipidemia, Hyperlipidemia, and Familial Hypercholesterolemia

Background

There are limited studies on the effects of cholesterol homeostasis in populations at high risk for cardiovascular disease. We aimed to use gas chromatography and flame-ionization detection (GC-FID) of non-cholesterol sterols as indicators of cholesterol absorption and synthesis. Sterol indicators of cholesterol absorption included campesterol, stigmasterol, and sitosterol. Sterol indicators of cholesterol synthesis included squalene, 7-lathosterol, and desmosterol.

Material/Methods

A total of 158 participants were enrolled in 3 groups: healthy control (n=64), hyperlipidemia (n=69), and familial hypercholesterolemia (FH, n=25). Age, sex, blood pressure, blood glucose, and lipoprotein were collected, and cholesterol absorption and synthesis markers were determined by GC-FID.

Results

All 6 cholesterol concentration indicators, except squalene, were significantly different among the 3 groups (all P<0.05); whereas in the ratio to cholesterol (%, sterols/cholesterol), only desmosterol and lathosterol were significantly different (P<0.05). Multifactorial regression analysis showed that triglycerides, total cholesterol, and desmosterol were independent risk factors affecting the development of hyperlipidemia (P<0.05). The efficacy of the ROC curve for the diagnosis of dyslipidemia was also higher for all 3 indices (Model 1, AUC=0.960). Model 1 was superior to Model 2 for the 6 indicators of cholesterol. For the FH and dyslipidemia groups, the 6-indicator model (Model 3) was shown to have a good diagnostic value (AUC=1.000).

Conclusions

The 6 sterol indicators of cholesterol absorption and synthesis had a dynamic course in all study participants. Desmosterol was an indicator of dyslipidemia. The combined use of the 6 sterol indicators differentiated between healthy individuals and patients with dyslipidemia and FH.

A Matched Case-Control Study of Noncholesterol Sterols and Fatty Acids in Chronic Hemodialysis Patients

Dyslipidemia is common among patients on hemodialysis, but its etiology is not fully understood. Although changes in cholesterol homeostasis and fatty acid metabolism play an important role during dialysis, the interaction of these metabolic pathways has yet to be studied in sufficient detail. In this study, we enrolled 26 patients on maintenance hemodialysis treatment (high-volume hemodiafiltration, HV HDF) without statin therapy (17 men/9 women) and an age/gender-matched group of 26 individuals without signs of nephropathy. The HV-HDF group exhibited more frequent signs of cardiovascular disease, disturbed saccharide metabolism, and altered lipoprotein profiles, manifesting in lower HDL-C, and raised concentrations of IDL-C and apoB-48 (all p < 0.01). HV-HDF patients had higher levels of campesterol (p < 0.01) and β-sitosterol (p = 0.06), both surrogate markers of cholesterol absorption and unchanged lathosterol concentrations. Fatty acid (FA) profiles were changed mostly in cholesteryl esters, with a higher content of saturated and n-3 polyunsaturated fatty acids (PUFA) in the HV-HDF group. However, n-6 PUFA in cholesteryl esters were less abundant (p < 0.001) in the HV-HDF group. Hemodialysis during end-stage kidney disease induces changes associated with higher absorption of cholesterol and disturbed lipoprotein metabolism. Changes in fatty acid metabolism reflect the combined effect of renal insufficiency and its comorbidities, mostly insulin resistance.

Xanthohumol Suppresses NPC1L1 Gene Expression through Downregulation of HNF-4α and Inhibits Cholesterol Uptake in Caco-2 Cells

Xanthohumol (Xan) is a prenylated chalcone mainly found in hops; it has been demonstrated to function against hypercholesterolemia, hyperlipidemia, and atherosclerosis. In this study, we focused on the hypocholesterolemic effect of Xan on cholesterol uptake and the underlying molecular mechanisms of Xan in human intestinal Caco-2 cells. The microarray data showed that Niemann-Pick C1-like 1 (NPC1L1), an essential transporter for dietary cholesterol absorption, was significantly downregulated in Xan-treated Caco-2 cells. We demonstrated that Xan (10 and 20 μM) suppressed the mRNA and protein expression of NPC1L1 by 0.65 ± 0.12-fold and 0.54 ± 0.15-fold and 0.72 ± 0.04-fold and 0.44 ± 0.12-fold, respectively, compared to that of the vehicle-treated Caco-2 cells. Moreover, Xan (10 and 20 μM) significantly inhibited cholesterol uptake by approximately 12 and 32% in Caco-2 cells. NPC1L1 promoter activity was significantly suppressed by Xan, and a DNA element within the NPC1L1 promoter involved in Xan-mediated NPC1L1 reduction located between the -120 and -20 positions was identified. Moreover, Xan markedly decreased the mRNA and protein levels of hepatocyte nuclear factor 4α (HNF-4α), a critical activator of NPC1L1 transcription, and subsequently attenuated HNF-4α/NPC1L1 promoter complex formation, resulting in the suppression of NPC1L1 gene expression. Finally, we demonstrated that Xan markedly abolished lovastatin-induced NPC1L1 overexpression in Caco-2 cells. These findings reveal that Xan suppresses NPC1L1 expression via downregulation of HNF-4α and exerts inhibitory effects on cholesterol uptake in the intestinal Caco-2 cells. Our findings suggest Xan could serve as a potential cholesterol-lowering agent and supplement for statin therapy.

Stigmasterol accumulation causes cardiac injury and promotes mortality

Cardiovascular disease is expected to remain the leading cause of death worldwide despite the introduction of proprotein convertase subtilisin/kexin type 9 inhibitors that effectively control cholesterol. Identifying residual risk factors for cardiovascular disease remains an important step for preventing and clinically managing the disease. Here we report cardiac injury and increased mortality occurring despite a 50% reduction in plasma cholesterol in a mouse model of phytosterolemia, a disease characterized by elevated levels of dietary plant sterols in the blood. Our studies show accumulation of stigmasterol, one of phytosterol species, leads to left ventricle dysfunction, cardiac interstitial fibrosis and macrophage infiltration without atherosclerosis, and increased mortality. A pharmacological inhibitor of sterol absorption prevents cardiac fibrogenesis. We propose that the pathological mechanism linking clinical sitosterolemia to the cardiovascular outcomes primarily involves phytosterols-induced cardiac fibrosis rather than cholesterol-driven atherosclerosis. Our studies suggest stigmasterol is a potent and independent risk factor for cardiovascular disease.

Decreasing the Cholesterol Burden in Heterozygous Familial Hypercholesterolemia Children by Dietary Plant Stanol Esters

This review covers the current knowledge about plant stanol esters as a dietary treatment option for heterozygous familial hypercholesterolemia (he-FH) children. The current estimation of the prevalence of he-FH is about one out of 200–250 persons. In this autosomal dominant disease, the concentration of plasma low-density lipoprotein cholesterol (LDL-C) is strongly elevated since birth. Quantitative coronary angiography among he-FH patients has revealed that stenosing atherosclerotic plaques start to develop in he-FH males in their twenties and in he-FH females in their thirties, and that the magnitude of the plaque burden predicts future coronary events. The cumulative exposure of coronary arteries to the lifelong LDL-C elevation can be estimated by calculating the LDL-C burden (LDL-C level × years), and it can also be used to demonstrate the usefulness of dietary stanol ester treatment. Thus, when compared with untreated he-FH patients, the LDL-C burden of using statin from the age of 10 is 15% less, and if he-FH patients starts to use dietary stanol from six years onwards and a combination of statin and dietary stanol from 10 years onwards, the LDL-C burden is 21% less compared to non-treated he-FH patients. We consider dietary stanol treatment of he-FH children as a part of the LDL-C-lowering treatment package as safe and cost-effective, and particularly applicable for the family-centered care of the entire he-FH families.

The Effect of Proprotein Convertase Subtilisin/Kexin Type 9 Inhibition on Sterol Absorption Markers in a Cohort of Real-World Patients

Background:

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is expressed in multiple tissues, including the small intestine. The effect of PCSK9 inhibition on cholesterol absorption is not known.

Objectives:

Measure serum cholesterol absorption markers before and after initiation of PCSK9 inhibitors.

Methods:

Single-center retrospective cohort of patients administered evolocumab and alirocumab between July 2015 and January 2017. Paired t tests were used to compare mean serum cholesterol marker concentrations, and ratios to total cholesterol, before and after PCSK9 inhibitor initiation. Analyses were repeated for those taking and not taking statins and taking or not taking ezetimibe at both initiation and follow-up, for each PCSK9 inhibitor, and based on follow-up time (<60, 60-120, and >120 days).

Results:

There were 62 possible participants, 34 were excluded for lack of data or unknown PCSK9 inhibitor initiation date. Average follow-up was 92.5 days. Mean campesterol (before 3.14 μg/mL, 95% CI: 2.79-4.38 μg/mL; after 2.09 μg/mL, 95% CI: 1.87-2.31 μg/mL; P < .0001), sitosterol (before 2.46 μg/mL, 95% CI: 2.23-2.70 μg/mL; after 1.62 μg/mL, 95% CI: 1.48-1.75 μg/mL; P < .0001), and cholestanol (before 3.25 μg/mL, 95% CI: 3.04-3.47 μg/mL; after 2.08 μg/mL, 95% CI: 1.96-2.21 μg/mL; P < .0001) all significantly decreased at follow-up. There was no significant change in absorption marker to total cholesterol ratios. Findings were not influenced by statin or ezetimibe use or nonuse, which PCSK9 inhibitor was prescribed, or time to follow-up.

Conclusion:

Proprotein convertase subtilisin/kexin type 9 inhibition was associated with decreased cholesterol absorption markers.

Increased cholesterol absorption rather than synthesis is involved in boosted protease inhibitor-associated hypercholesterolaemia

OBJECTIVE

The aim of this study was to compare the differential effects of first-line efavirenz (EFV)-based vs. boosted lopinavir-based antiretroviral regimens on cholesterol metabolism.

DESIGN

Multicentre, open-label, randomized clinical trial.

METHODS

Forty-nine naive HIV-infected patients were randomized (1 : 1) to receive either ritonavir-boosted lopinavir (LPV/r) or EFV both in combination with tenofovir and emtricitabine (ClinicalTrials.gov: NCT00759070). Lipid profile and serum phytosterols and cholesterol precursors were determined at baseline and after 16 weeks.

RESULTS

After 16 weeks of intervention, total and non-HDL cholesterol as well as triglyceride levels significantly increased in the LPV/r-group (+1.0 ± 0.8; +0.8 ± 0.7 and +0.8 ± 1.5 mmol/l, respectively), but not in the EFV-group (+0.4 ± 0.7; +0.4 ± 0.6 and 0.2 ± 0.5 mmol/l, respectively). Markers of cholesterol absorption (campesterol-to-cholesterol and sitosterol-to-cholesterol ratios) significantly increased in the LPV/r-group, but not in the EFV-group, whereas there were no changes in either group of the lathosterol-to-cholesterol ratio, a marker of cholesterol synthesis.

CONCLUSION

Treatment with an LPV/r-based therapy increased total cholesterol relative to EFV-based therapy. Our data suggest that absorption rather than synthesis is the mechanism involved in LPV/r-associated increased total cholesterol.

Dietary phytosterol does not accumulate in the arterial wall and prevents atherosclerosis of LDLr-KO mice

SCOPE

There have been conflicting reports on the usefulness of phytosterols (PS) in preventing atherosclerosis. We evaluated the effects of dietary PS supplementation in LDLr-KO male mice on the plasma and aorta sterol concentrations and on atherosclerotic lesion development.

METHODS AND RESULTS

Mice were fed a high fat diet (40% of energy) supplemented with or without PS (2% w/w, n = 10). Plasma and arterial wall cholesterol and PS concentrations, lesion area, macrophage infiltration, and mRNA expression from LOX-1, CD36, ABCA1 and ABCG1 in peritoneal macrophages were measured. After 16 weeks, the plasma cholesterol concentration in PS mice was lower than that in the controls (p = 0.02) and in the arterial wall (p = 0.03). Plasma PS concentrations were higher in PS-fed animals than in controls (p < 0.0001); however, the arterial wall PS concentration did not differ between groups. The atherosclerotic lesion area in the PS group (n = 5) was smaller than that in controls (p = 0.0062) and the macrophage area (p = 0.0007). PS correlates negatively with arterial lipid content and macrophage (r = -0.76; p < 0.05). PS supplementation induced lower ABCG1 mRNA expression (p < 0.05).

CONCLUSIONS

Despite inducing an increase in PS plasma concentration, PS supplementation is not associated with its accumulation in the arterial wall and prevents atherosclerotic lesion development.

Plasma plant sterols serve as poor markers of cholesterol absorption in man

The validation of the use of plasma plant sterols as a marker of cholesterol absorption is frail. Nevertheless, plant sterol concentrations are routinely used to describe treatment-induced changes in cholesterol absorption. Their use has also been advocated as a clinical tool to tailor cholesterol-lowering therapy. Prior to wider implementation, however, the validity of plant sterols as absorption markers needs solid evaluation. Therefore, we compared plasma plant sterol concentrations to gold-standard stable isotope-determined cholesterol absorption. Plasma campesterol/TC concentrations (camp/TC) were measured in a population of 175 mildly hypercholesterolemic individuals (age: 59.7 ± 5.6 years; BMI: 25.5 ± 2.9 kg/m(2); LDL-C: 4.01 ± 0.56 mmol/l). We compared cholesterol absorption according to the plasma dual-isotope method in subjects with the highest camp/TC concentrations (N = 41, camp/TC: 2.14 ± 0.68 μg/mg) and the lowest camp/TC concentrations (N = 39, camp/TC: 0.97 ± 0.22 μg/mg). Fractional cholesterol absorption did not differ between the groups (24 ± 12% versus 25 ± 16%, P = 0.60), nor was it associated with plasma camp/TC concentrations in the total population of 80 individuals (β = 0.13; P = 0.30, adjusted for BMI and plasma triglycerides). Our findings do not support a relation between plasma plant sterol concentrations and true cholesterol absorption and, therefore, do not favor the use of these sterols as markers of cholesterol absorption. This bears direct consequences for the interpretation of earlier studies, as well as for future studies targeting intestinal regulation of cholesterol metabolism.

Effects of a 2-y dietary weight-loss intervention on cholesterol metabolism in moderately obese men

BACKGROUND

Long-term dietary weight loss results in complex metabolic changes. However, its effect on cholesterol metabolism in obese subjects is still unclear.

OBJECTIVE

We assessed the effects of 2 y of weight loss achieved with various diet regimens on phytosterols (markers of intestinal cholesterol absorption), lanosterol (marker of de novo cholesterol synthesis), and changes in apolipoprotein concentrations.

DESIGN

We conducted the 2-y Dietary Intervention Randomized Controlled Trial (DIRECT-a study of low-fat, Mediterranean, and low-carbohydrate diets). We assessed circulating phytosterol and lanosterol concentrations and their ratios to cholesterol and apolipoproteins A-I and B-100 in 90 DIRECT participants at 0, 6, and 24 mo.

RESULTS

We observed a significant upregulation of the markers of cholesterol absorption (campesterol: +16.8%, P < 0.001) and a downregulation of the markers of cholesterol synthesis (lanosterol: -16.5%, P = 0.008) during the active weight-loss phase (first 6 mo, weight loss of 5%, 6%, and 10% in the 3 diet groups, respectively), followed by a rebound (campesterol: -6.2%, P = 0.045; lanosterol: +43.7%, P < 0.001) during the next 18 mo (weight gain of 1%, 1%, and 2% in the 3 diet groups, respectively). HDL cholesterol continuously increased during the study (17.0%, P < 0.001), whereas LDL cholesterol remained constant. At the end of the 24-mo follow-up period, campesterol (P < 0.001) and lanosterol (P = 0.016) amounts were significantly higher than baseline values. The concentration of apolipoprotein B-100 correlated with cholesterol metabolism (ρ = 0.299 and P = 0.020 for lanosterol; ρ = -0.105 and NS for campesterol), and the homeostasis model assessment of insulin resistance correlated with lanosterol (ρ = 0.09, P = 0.001).

CONCLUSIONS

Long-term weight loss is related to a characteristic response suggestive of altered cholesterol and apolipoprotein metabolism. Various diets have a similar effect on these effects. DIRECT is registered at clinicaltrials.gov as NCT00160108.

Baseline cholesterol absorption and the response to ezetimibe/simvastatin therapy: a post-hoc analysis of the ENHANCE trial

Subjects with increased cholesterol absorption might benefit more from statin therapy combined with a cholesterol absorption inhibitor. We assessed whether baseline cholesterol absorption markers were associated with response to ezetimibe/simvastatin therapy, in terms of LDL-cholesterol (LDL-C) lowering and cholesterol absorption inhibition, in patients with familial hypercholesterolemia (FH). In a posthoc analysis of the two-year ENHANCE trial, we assessed baseline cholesterol-adjusted campesterol (campesterol/TC) and sitosterol/TC ratios in 591 FH patients. Associations with LDL-C changes and changes in cholesterol absorption markers were evaluated by multiple regression analysis. No association was observed between baseline markers of cholesterol absorption and the extent of LDL-C response to ezetimibe/simvastatin therapy (beta = 0.020, P = 0.587 for campesterol/TC and beta<0.001, P = 0.992 for sitosterol/TC). Ezetimibe/simvastatin treatment reduced campesterol levels by 68% and sitosterol levels by 62%; reductions were most pronounced in subjects with the highest cholesterol absorption markers at baseline, the so-called high absorbers (P < 0.001). Baseline cholesterol absorption status does not determine LDL-C lowering response to ezetimibe/simvastatin therapy in FH, despite more pronounced cholesterol absorption inhibition in high absorbers. Hence, these data do not support the use of baseline absorption markers as a tool to determine optimal cholesterol lowering strategy in FH patients. However, due to the exploratory nature of any posthoc analysis, these results warrant further prospective evaluation in different populations.

Serum sterol responses to increasing plant sterol intake from natural foods in the Mediterranean diet

BACKGROUND

Phytosterols in natural foods are thought to inhibit cholesterol absorption. The Mediterranean diet is rich in phytosterol-containing plant foods.

AIM OF THE STUDY

To assess whether increasing phytosterol intake from natural foods was associated with a cholesterol-lowering effect in a substudy of a randomized trial of nutritional intervention with Mediterranean diets for primary cardiovascular prevention (PREDIMED study).

METHODS

One hundred and six high cardiovascular risk subjects assigned to two Mediterranean diets supplemented with virgin olive oil (VOO) or nuts, which are phytosterol-rich foods, or advice on a low-fat diet. Outcomes were 1-year changes in nutrient intake and serum levels of lipids and non-cholesterol sterols.

RESULTS

Average phytosterol intake increased by 76, 158 and 15 mg/day in participants assigned VOO, nuts and low-fat diets, respectively. Compared to participants in the low-fat diet group, changes in outcome variables were observed only in those in the Mediterranean diet with nuts group, with increases in intake of fibre, polyunsaturated fatty acids and phytosterols (P < 0.020, all) and significant (P < 0.05) reductions of LDL-cholesterol (0.27 mmol/l or 8.3%) and the LDL/HDL-cholesterol ratio (0.29 mmol/l or 11.5%). Variations in saturated fat, cholesterol or fibre intake were unrelated to LDL-cholesterol changes. In the whole group, changes in serum sitosterol-to-cholesterol, which reflect those of dietary phytosterol intake and absorption, correlated inversely to LDL-cholesterol changes (r = -0.256; P = 0.008). In multivariate analyses, baseline LDL-cholesterol, increases in serum sitosterol ratios and statin use were independently associated with LDL-cholesterol reductions.

CONCLUSIONS

Small amounts of phytosterols in natural foods appear to be bioactive in cholesterol lowering.

Phytosterol-enriched products on the Irish market: examination of intake and consumption patterns

Objective

To study patterns of phytosterol intakes in the Irish population from enriched sources.

Design

An interview-assisted questionnaire, which recorded information on sociodemographics, product types, intake amounts and patterns of intake. Independent samplesttests, one-way ANOVA and cross-tabulations were used to establish significant relationships between groups of variables. The top tertile of phytosterol intakes was also calculated.

Setting

Point-of-purchase of phytosterol-enriched products in Irish supermarkets.

Subjects

Four hundred and sixty-eight consumers (186 men and 282 women) of phytosterol-enriched foods.

Results

The mean phytosterol intake from enriched sources for the sample population was 2·45 g/d. Men had greater intakes than women (2·71 g/dv. 2·29 g/d, respectively). A total of 62 % of consumers were unaware of the importance of consuming fruit and vegetables while taking these products. The majority of respondents reported that they had high cholesterol (61 %) and 22 % of consumers also took cholesterol-lowering medication (statins). In total, 23 % had phytosterol intakes >3·0 g/d and the majority of consumers (58 %) had been consuming these products for >1 year. The mean intake for respondents with phytosterol intakes >3·0 g/d was 4·1 g/d and 74 % of this subgroup had been consuming these products for >1 year.

Conclusion

In general, phytosterol intakes are within efficacious levels in the Irish population. However, there appears to be a subgroup that has been consuming these products at intakes greater than current recommendations for >1 year.

Effects of ezetimibe and/or simvastatin on LDL receptor protein expression and on LDL receptor and HMG-CoA reductase gene expression: a randomized trial in healthy men

OBJECTIVE

The combination of simvastatin, an HMG-CoA reductase inhibitor, and ezetimibe, an inhibitor of Niemann-Pick C1-like 1 protein, decreases cholesterol synthesis and absorption and reduces circulating LDL-cholesterol concentrations. The molecular mechanisms underlying the pronounced lipid-lowering effects of this combination have not been fully elucidated in humans.

METHODS AND RESULTS

One center, prospective, randomized, parallel three-group study in 72 healthy men (mean age 32+/-9 years, mean body mass index 25.7+/-3.2 kg/m(2)). Each group of twenty-four subjects received a 14-day treatment with either ezetimibe (10mg/day), simvastatin (40 mg/day) or their combination. Lipid levels, the ratio of non-cholesterol sterols to cholesterol concentrations (used as markers of cholesterol synthesis and absorption), cell surface LDL receptor (LDLR) protein as well as LDLR and HMG-CoA reductase gene expression in mononuclear blood cells were measured at baseline and at the end of the study. LDL-C decreased in all groups. Simvastatin decreased, ezetimibe increased and their combination had no effect on HMG-CoA reductase activity. Simvastatin and the combination of ezetimibe and simvastatin increased the HMG-CoA reductase and LDLR gene expression while ezetimibe had no effect. The cell surface LDLR protein expression remained unchanged in all groups. The combination of ezetimibe and simvastatin increased the expression of the serine protease proprotein convertase subtilisin/kexin 9 (PCSK9), an enzyme shown to down-regulate LDLR protein levels.

CONCLUSIONS

The co-administration of ezetimibe and simvastatin abrogates the ezetimibe-induced increase in cholesterol synthesis and up-regulates the LDLR gene but not protein expression, an effect possibly mediated through a parallel upregulation of PCSK9 expression.

Examination of encapsulated phytosterol ester supplementation on lipid indices associated with cardiovascular disease

OBJECTIVE

As opposed to traditional food based delivery we examined the efficacy of ingesting encapsulated phytosterol esters on indices of lipid health in hypercholesterolemic adults.

METHODS

We performed a randomized, double-blinded, parallel-group, placebo-controlled, clinical intervention examining 54 men and women (20-70 y of age) with a low-density lipoprotein cholesterol (LDL-C) level > or =3.33 mmol/L. Participants were not taking cholesterol-lowering medications. Treatment consisted of ingesting 2.6 g of encapsulated phytosterol esters (n = 25) or a matching placebo (n = 29) for 12 wk.

RESULTS

Total cholesterol (TC) levels at baseline (mean +/- SD) were 6.29 +/- 0.7 mmol/L in the phytosterol group and 6.00 +/- 0.7 mmol/L in the placebo group. Baseline LDL-C levels were 4.27 +/- 0.7 mmol/L in the treatment group and 4.00 +/- 0.8 mmol/L in the placebo group. Analysis of variance and Tukey's least significant difference post hoc analyses revealed a significant within-group reduction in TC (-0.23 +/- 0.4 mmol/L, P < 0.05) and LDL-C (-0.22 +/- 0.5 mmol/L, P < 0.05) for the phytosterol treatment group. Mean reductions in TC and LDL-C were greater than placebo (P < 0.05). Percentages of change from baseline for TC were -3.52% (95% confidence interval -6.44 to -0.40) for phytosterol treatment and 2.64% (95% confidence interval 0.30-5.60) for placebo. Those for LDL-C were -5.00% (95% confidence interval -9.92 to -0.08) for phytosterol and 4.89 (95% confidence interval 0.24-9.5) for placebo. No other significant effects were observed.

CONCLUSION

Encapsulated phytosterol ester ingestion appears to positively modulate LDL-C. Given that the reduction in LDL-C was not as extensive as in food-based trials, future investigations should examine potential timing and dose issues relative to encapsulated delivery.

Cholesterol and Glucose Metabolism and Recurrent Cardiovascular Events Among the Elderly

OBJECTIVES

The aim of this research was to evaluate the prognostic value of cholesterol absorption assessed with the serum cholestanol-to-cholesterol concentration ratio (lower level reflects decreased cholesterol absorption) among elderly cardiovascular patients (DEBATE [Drugs and Evidence-Based Medicine in the Elderly] study).

BACKGROUND

The components of the metabolic syndrome have been unexpectedly associated with better prognosis among elderly cardiovascular patients. On the other hand, a metabolic syndrome-type state is characterized by high synthesis and decreased absorption of cholesterol.

METHODS

This was a prospective cohort study of home-dwelling individuals age 75 years and older with cardiovascular diseases (247 women, 129 men) recruited from the community. Main outcome measure was multivariate-adjusted time to 3.4-year mortality and recurrent major cardiovascular events.

RESULTS

Serum total and low-density lipoprotein cholesterol levels did not predict outcome. Instead, the mortality risk (64 deaths) increased with increasing levels of cholestanol-to-cholesterol ratio. Patients in the 2nd, 3rd, and 4th quartiles had a relative hazard ratio (HR) for death of 2.54 (95% confidence interval [CI] 1.05 to 6.12), 2.48 (95% CI 1.03 to 6.00), and 3.53 (95% CI 1.52 to 8.19) compared with the lowest quartile, even though 50% of individuals in the lowest cholestanol quartile had metabolic syndrome or diabetes. In multivariate models, the lowest cholestanol ratio quartile was independently associated with lower mortality (relative HR, 0.37, 95% CI 0.17 to 0.81), and with fewer major cardiovascular events (115 events, relative HR, 0.59, 95% CI 0.35 to 0.98).

CONCLUSIONS

Low cholesterol absorption was associated with fewer recurrent cardiovascular events, and with better survival in elderly patients despite frequent abnormalities of glucose metabolism.

Cholesterol absorption: influence of body weight and the role of plant sterols

Cholesterol absorption and synthesis are inter-regulated, so if one changes then the other changes in the opposite direction. The regulation and detailed mechanism of cholesterol absorption have been intensely investigated. Inhibition of cholesterol absorption has become an additional factor for cholesterol lowering. Agents inhibiting cholesterol absorption, mainly plant stanols and sterols or ezetimibe, usually lower low-density lipoprotein cholesterol in monotherapy by less than 20%, indicating that these inhibitors can normalize cholesterol levels only in patients with a modest baseline hypercholesterolemia. Body weight, especially obesity with and without diabetes, and dietary plant sterols alter cholesterol absorption differently. This article briefly reviews some special questions of cholesterol absorption under these conditions.