Alterations in cholesterol absorption/synthesis markers characterize Framingham offspring study participants with CHD

The profile of cholesterol metabolism does not interfere with the cholesterol-lowering efficacy of phytostanol esters

BACKGROUND & AIMS

Increasing evidence suggests that high cholesterol absorption efficiency enhances the risk of atherosclerotic cardiovascular diseases. It is not known whether inhibiting cholesterol absorption has different metabolic effects in high- vs. low cholesterol absorbers. We evaluated the effects of phytostanol esters on serum lipids and cholesterol metabolism in a post hoc study of three randomized, double-blind, controlled trials. The participants were classified into low (n = 20) and high (n = 21) cholesterol absorbers by median cholesterol absorption efficiency based on the plasma cholesterol absorption marker cholestanol at baseline.

METHODS

The participants consumed mayonnaise or margarine without or with phytostanol esters for six to nine weeks without other changes in the diet or lifestyle. Serum cholesterol, cholestanol, lathosterol, and faecal neutral sterols and bile acids were analysed by gas-liquid chromatography. According to power calculations, the size of the study population (n = 41) was appropriate.

RESULTS

During the control period, cholesterol synthesis, and faecal neutral sterols and bile acids were lower in high- vs. low absorbers (p < 0.05 for all). Phytostanol esters reduced low-density lipoprotein cholesterol by 10-13% in both groups, and directly measured cholesterol absorption efficiency by 41 ± 7% in low- and 47 ± 5% in high absorbers (p < 0.001 for all) without side effects. Cholesterol synthesis and faecal neutral sterols (p < 0.01) increased in both groups, more markedly in the high vs. low absorbers (p < 0.01).

CONCLUSIONS

Low cholesterol absorption combined with high faecal neutral sterol excretion are components of reverse cholesterol transport. Thus, high- vs. low absorbers had a more disadvantageous metabolic profile at baseline. In both groups, phytostanol esters induced favourable changes in serum, lipoprotein, and metabolic variables known to help in prevention of the development of atherosclerotic cardiovascular diseases.

Phytosterol intake and risk of coronary artery disease: Results from 3 prospective cohort studies

BACKGROUND

Phytosterols are structurally similar to cholesterol and partially inhibit intestinal absorption of cholesterol, although their impact on coronary artery disease (CAD) risk remains to be elucidated.

OBJECTIVES

This study aimed to prospectively assess the associations between total and individual phytosterol intake and CAD risk in United States health professionals.

METHODS

The analysis included 213,992 participants from 3 prospective cohorts-the Nurses' Health Study (NHS), NHSII, and Health Professionals Follow-Up Study-without cardiovascular disease or cancer at baseline. Diet was assessed using a validated food frequency questionnaire every 2-4 y since baseline. Associations between phytosterol intake and the risk of CAD, such as nonfatal myocardial infarction and fatal CAD, were evaluated using Cox proportional hazards regression models.

RESULTS

More than 5,517,993 person-years, 8725 cases with CAD were documented. Comparing extreme quintiles, pooled hazard ratios (95% CIs) of CAD were 0.93 (0.86, 1.01; P-trend = 0.16) for total phytosterols, 0.89 (0.82, 0.96; P-trend = 0.05) for campesterol, 0.95 (0.88, 1.02; P-trend = 0.10) for stigmasterol, and 0.92 (0.85, 1.00; P-trend = 0.09) for β-sitosterol. Nonlinear associations were observed for total phytosterols, campesterol, and β-sitosterol: the risk reduction plateaued at intakes above ∼180, 30, and 130 mg/d, respectively (P-nonlinearity < 0.001). In a subset of participants (N range between 11,983 and 22,039), phytosterol intake was inversely associated with plasma concentrations of total cholesterol, triglycerides, high-density lipoprotein cholesterol, and IL-6 and positively associated with adiponectin, whereas no significant associations were observed for low-density lipoprotein cholesterol or C-reactive protein concentrations.

CONCLUSIONS

Higher long-term intake of total and major subtypes of phytosterols may be associated with a modest reduction in CAD risk, displaying a nonlinear relationship that plateau at moderate intake levels. The role of phytosterols in preventing CAD warrants further investigation.

Association of Serum Levels of Cholesterol Absorption and Synthesis Markers with the Presence of Cardiovascular Disease: The CACHE Study CVD Analysis

AIM

Serum levels of cholesterol absorption and synthesis markers have been associated with cardiovascular risk in the United States and European countries. In this study, we examined the relevance of these biomarkers and the presence of cardiovascular disease (CVD) in Japanese individuals.

METHODS

The CACHE consortium, comprising of 13 research groups in Japan possessing data on campesterol, an absorption marker, and lathosterol, a synthesis marker measured by gas chromatography, compiled the clinical data using the REDCap system.

RESULTS

Among the 2,944 individuals in the CACHE population, those with missing campesterol or lathosterol data were excluded. This cross-sectional study was able to analyze data from 2,895 individuals, including 339 coronary artery disease (CAD) patients, 108 cerebrovascular disease (CeVD) patients, and 88 peripheral artery disease (PAD) patients. The median age was 57 years, 43% were female, and the median low-density lipoprotein cholesterol and triglyceride levels were 118 mg/dL and 98 mg/dL, respectively. We assessed the associations of campesterol, lathosterol, and the ratio of campesterol to lathosterol (Campe/Latho ratio) with the odds of CVD using multivariable-adjusted nonlinear regression models. The prevalence of CVD, especially CAD, showed positive, inverse, and positive associations with campesterol, lathosterol, and the Campe/Latho ratio, respectively. These associations remained significant even after excluding individuals using statins and/or ezetimibe. The associations of the cholesterol biomarkers with PAD were determined weaker than those with CAD. Contrarily, no significant association was noted between cholesterol metabolism biomarkers and CeVD.

CONCLUSION

This study showed that both high cholesterol absorption and low cholesterol synthesis biomarker levels were associated with high odds of CVD, especially CAD.

Serum Values of Cholesterol Absorption and Synthesis Biomarkers in Japanese Healthy Subjects: The CACHE Study HEALTHY Analysis

AIM

Blood cholesterol absorption and synthesis biomarkers predict cardiovascular risk. This study aimed to determine the values of serum non-cholesterol sterol markers [lathosterol (Latho), campesterol (Campe), and sitosterol (Sito)] in healthy individuals and factors affecting these markers.

METHODS

The CACHE Consortium compiled clinical data, including serum Latho (cholesterol synthesis marker), and Campe and Sito (cholesterol absorption markers), by a gas chromatography method in 2944 individuals. Healthy subjects were selected by excluding those with prior cardiovascular disease, diabetes mellitus, hypertension, chronic kidney disease, familial hypercholesterolemia, sitosterolemia, current smokers, those with low (＜17 kg/m2) or high (≥ 30 kg/m2) body mass index (BMI), and those with treatment for dyslipidemia or hyperuricemia. Nonlinear regression stratified by sex was used to examine the associations of cholesterol metabolism markers with age, BMI, and serum lipid levels.

RESULTS

Of 479 individuals selected, 59.4% were female; the median age was 48 years in females and 50 years in males. The three markers showed positively skewed distributions, and sex differences were present. Age was associated positively with Latho, inversely with Campe, but not significantly with Sito. BMI was associated positively with Latho, but not significantly with Campe or Sito. High-density lipoprotein cholesterol (HDL-C) was positively associated with Campe and Sito, but not significantly with Latho. Non-HDL-C was positively associated with the three markers.

CONCLUSION

Our study results in the healthy subjects help to interpret the non-cholesterol sterol markers for cardiovascular risk assessment in patients with cardiovascular risk factors.

High cholesterol absorption: A risk factor of atherosclerotic cardiovascular diseases?

Lowering elevated low-density lipoprotein cholesterol (LDL-C) concentrations reduces the risk of atherosclerotic cardiovascular diseases (ASCVDs). However, increasing evidence suggests that cholesterol metabolism may also be involved in the risk reduction of ASCVD events. In this review, we discuss if the different profiles of cholesterol metabolism, with a focus on high cholesterol absorption, are atherogenic, and what could be the possible mechanisms. The potential associations of cholesterol metabolism and the risk of ASCVDs are evaluated from genetic, metabolic, and population-based studies and lipid-lowering interventions. According to these studies, loss-of-function genetic variations in the small intestinal sterol transporters ABCG5 and ABCG8 result in high cholesterol absorption associated with low cholesterol synthesis, low cholesterol elimination from the body, and a high risk of ASCVDs. In contrast, loss-of-function genetic variations in another intestinal sterol transporter, NPC1L1 result in low cholesterol absorption associated with high cholesterol synthesis, elevated cholesterol elimination from the body, and low risk of ASCVDs. Statin monotherapy is not sufficient to reduce the ASCVD risk in cases of high cholesterol absorption, and these individuals need combination therapy of statin with cholesterol absorption inhibition. High cholesterol absorption, i.e., >60%, is estimated to occur in approximately one third of a population, so taking it into consideration is important to optimise lipid-lowering therapy to prevent atherosclerosis and reduce the risk of ASCVD events.

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.

Blood phytosterols in relation to cardiovascular diseases and mediating effects of blood lipids and hematological traits: a Mendelian randomization analysis

BACKGROUND

Short-term clinical trials have shown the cholesterol-lowering potentials of phytosterols, but their impacts on cardiovascular disease (CVD) remain controversial. This study used the Mendelian randomization (MR) to investigate the relationships between genetic predisposition to blood sitosterol concentration and 11 CVD endpoints, along with the potential mediating effects of blood lipids and hematological traits.

METHODS

Random-effect inverse-variance weighted method was used as the main analysis of MR. Genetic instruments of sitosterol (seven SNPs, F = 253, and R² = 15.4 %) were derived from an Icelandic cohort. Summary-level data of the 11 CVDs were obtained from UK Biobank, FinnGen, and publicly available genome-wide association study results.

RESULTS

Genetically predicted one unit increment in log-transformed blood total sitosterol was significantly associated with a higher risk of coronary atherosclerosis (OR: 1.52; 95 % CI: 1.41, 1.65; n = 667,551), myocardial infarction (OR: 1.40; 95 % CI: 1.25, 1.56; n = 596,436), all coronary heart disease (OR: 1.33; 95 % CI: 1.22, 1.46; n = 766,053), intracerebral hemorrhage (OR: 1.68; 95 % CI: 1.24, 2.27; n = 659,181), heart failure (OR: 1.16; 95 % CI: 1.08, 1.25; n = 1,195,531), and aortic aneurysm (OR: 1.74; 95 % CI: 1.42, 2.13; n = 665,714). Suggestive associations were observed for an increased risk of ischemic stroke (OR: 1.06; 95 % CI: 1.01, 1.12; n = 2,021,995) and peripheral artery disease (OR: 1.20; 95 % CI: 1.05, 1.37; n = 660,791). Notably, blood non-high-density lipoprotein cholesterol (nonHDL-C) and apolipoprotein B mediated about 38-47 %, 46-60 %, and 43-58 % of the associations between sitosterol and coronary atherosclerosis, myocardial infarction, and coronary heart disease, respectively. However, the associations between sitosterol and CVDs were less likely to depend on hematological traits.

CONCLUSION

The study suggests that genetic predisposition to higher blood total sitosterol is linked to a greater risk of major CVDs. Moreover, blood nonHDL-C and apolipoprotein B might mediate a significant proportion of the associations between sitosterol and coronary diseases.

Comparative Gut Microbiome Differences between High and Low Aortic Arch Calcification Score in Patients with Chronic Diseases

Gut dysbiosis can induce chronic inflammation and contribute to atherosclerosis and vascular calcification. The aortic arch calcification (AoAC) score is a simple, noninvasive, and semiquantitative assessment tool to evaluate vascular calcification on chest radiographs. Few studies have discussed the relationship between gut microbiota and AoAC. Therefore, this study aimed to compare the microbiota composition between patients with chronic diseases and high or low AoAC scores. A total of 186 patients (118 males and 68 females) with chronic diseases, including diabetes mellitus (80.6%), hypertension (75.3%), and chronic kidney disease (48.9%), were enrolled. Gut microbiota in fecal samples were analyzed by sequencing of the 16S rRNA gene, and differences in microbial function were examined. The patients were divided into three groups according to AoAC score, including 103 patients in the low AoAC group (AoAC ≤ 3), 40 patients in the medium AoAC group (3 < AoAC ≤ 6), and 43 patients in the high AoAC group (AoAC > 6). Compared to the low AoAC group, the high AoAC group had a significantly lower microbial species diversity (Chao1 index and Shannon index) and increased microbial dysbiosis index. Beta diversity showed that the microbial community composition was significantly different among the three groups (p = 0.041, weighted UniFrac PCoA). A distinct microbial community structure was found in the patients with a low AoAC, with an increased abundance at the genus level of Agathobacter, Eubacterium coprostanoligenes group, Ruminococcaceae UCG-002, Barnesiella, Butyricimonas, Oscillibacter, Ruminococcaceae DTU089, and Oxalobacter. In addition, there was an increased relative abundance of class Bacilli in the high AoAC group. Our findings support the association between gut dysbiosis and the severity of AoAC in patients with chronic diseases.

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.

Serum Low Density Lipoprotein Cholesterol Concentration Is Not Dependent on Cholesterol Synthesis and Absorption in Healthy Humans

Introduction. Pharmacological reduction of cholesterol (C) synthesis and C absorption lowers serum low-density lipoprotein C (LDL-C) concentrations. We questioned whether high baseline C synthesis or C absorption translates into high serum LDL-C concentrations or if there was no connection. Therefore, we studied the association between serum LDL-C and C synthesis or C absorption in healthy subjects. Methods. Three published data sets of young subjects on different diets (study 1), mildly hypercholesterolemic subjects without cardiovascular disease (study 2) and healthy controls of the Framingham study (study 3) were used. The three study populations varied in sex, age, and weight. C synthesis and C fractional absorption rate (FAR) were measured with fecal sterol balance and stable isotope techniques (studies 1 and 2). Additionally, serum lathosterol and campesterol concentrations corrected for the serum total C concentration (R_lathosterol and R_campesterol) were used as markers for hepatic C synthesis and C FAR, respectively (studies 1−3). Linear regression analysis was applied to evaluate associations between LDL-C, C synthesis, and C absorption. Results. Seventy-three, 37, and 175 subjects were included in studies 1, 2, and 3, respectively. No statistically significant associations were found between LDL-C and the measured C synthesis and C FAR, nor for R_lathosterol and R_campesterol in any of the study groups. This lack of associations was confirmed by comparing the male subjects of studies 1 and 2. Study 1 subjects had a 50% lower serum LDL-C than the study 2 subjects (p < 0.01), but not a lower C synthesis, C FAR, R-lathosterol, or R_campesterol. Conclusions. Under physiological conditions, C synthesis and C FAR are not major determinants of circulating serum LDL-C concentrations in healthy subjects. The results need to be confirmed in large-scale studies in healthy subjects and patients at risk for cardiovascular disease.

Plasma Campesterol Is Positively Associated with Carotid Plaques in Asymptomatic Subjects

BACKGROUND

Increased cholesterol absorption and reduced synthesis are processes that have been associated with cardiovascular disease risk in a controversial way. However, most of the studies involving markers of cholesterol synthesis and absorption include conditions, such as obesity, diabetes, dyslipidemia, which can be confounding factors. The present study aimed at investigating the relationships of plasma cholesterol synthesis and absorption markers with cardiovascular disease (CVD) risk factors, cIMT (carotid intima-media thickness), and the presence of carotid plaques in asymptomatic subjects.

METHODS

A cross-sectional study was carried out in 270 asymptomatic individuals and anthropometrical parameters, fasting plasma lipids, glucometabolic profiles, high-sensitivity C-reactive protein (hs-CRP), markers of cholesterol synthesis (desmosterol and lathosterol), absorption (campesterol and sitosterol), cIMT, and the presence of atherosclerotic plaques were analyzed.

RESULTS

Among the selected subjects aged between 19 and 75 years, 51% were females. Age, body mass index, systolic and diastolic blood pressure, total cholesterol, non-HDL-C, triglycerides, glucose, and lathosterol/sitosterol ratios correlated positively with cIMT (p ≤ 0.05). Atherosclerotic plaques were present in 19% of the subjects. A direct association of carotid plaques with campesterol, OR = 1.71 (95% CI = 1.04-2.82, p ≤ 0.05) and inverse associations with both ratios lathosterol/campesterol, OR = 0.29 (CI = 0.11-0.80, p ≤ 0.05) and lathosterol/sitosterol, OR = 0.45 (CI = 0.22-0.95, p ≤ 0.05) were observed in univariate logistic regression analysis.

CONCLUSIONS

The findings suggested that campesterol may be associated with atherosclerotic plaques and the lathosterol/campesterol or sitosterol ratios suggested an inverse association. Furthermore, synthesis and absorption of cholesterol are inverse processes, and the absorption marker, campesterol, may reflect changes in body cholesterol homeostasis with atherogenic potential.

Relationship between Diabetes Mellitus and Serum Lathosterol and Campesterol Levels: The CACHE Study DM Analysis

AIM

Risk of cardiovascular disease is increased in patients with diabetes mellitus (DM). Cholesterol metabolism (hepatic synthesis and intestinal absorption) is known to be associated with cardiovascular risk. Next, we examined the association of DM with cholesterol absorption/synthesis.

METHODS

The CACHE Consortium, which is comprised of 13 research groups in Japan possessing data of lathosterol (Latho, synthesis marker) and campesterol (Campe, absorption marker) measured by gas chromatography, compiled the clinical data using the REDCap system. Among the 3597 records, data from 2944 individuals were used for several analyses including this study.

RESULTS

This study analyzed data from eligible 2182 individuals including 830 patients with DM; 42.2% were female, median age was 59 years, and median HbA1c of patients with DM was 7.0%. There was no difference in Latho between DM and non-DM individuals. Campe and Campe/Latho ratio were significantly lower in DM individuals than in non-DM individuals. When the associations of glycemic control markers with these markers were analyzed with multivariable-adjusted regression model using restricted cubic splines, Campe and Campe/Latho ratio showed inverse associations with glucose levels and HbA1c. However, Latho showed an inverted U-shaped association with plasma glucose, whereas Latho showed a U-shaped association with HbA1c. These associations remained even after excluding statin and/or ezetimibe users.

CONCLUSION

We demonstrated that DM and hyperglycemia were independent factors for lower cholesterol absorption marker levels regardless of statin/ezetimibe use.

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.

Plasma lathosterol measures rates of cholesterol synthesis and efficiency of dietary phytosterols in reducing the plasma cholesterol concentration

OBJECTIVES

Because the plasma campesterol/cholesterol ratio does not differ between groups that absorb different amounts of cholesterol, the authors investigated whether the plasma Phytosterols (PS) relate to the body's cholesterol synthesis rate measured as non-cholesterol sterol precursors (lathosterol).

METHOD

The authors studied 38 non-obese volunteers (58±12 years; Low-Density Lipoprotein Cholesterol ‒ LDL-C ≥ 130 mg/dL) randomly assigned to consume 400 mL/day of soy milk (Control phase) or soy milk + PS (1.6 g/day) for four weeks in a double-blind, cross-over study. PS and lathosterol were measured in plasma by gas chromatography coupled to mass spectrophotometry.

RESULTS

PS treatment reduced plasma total cholesterol concentration (-5.5%, p < 0.001), LDL-C (-7.6%, p < 0.001), triglycerides (-13.6%, p < 0.0085), and apolipoprotein B (apo B) (-6.3%, p < 0.008), without changing high density lipoprotein cholesterol (HDL-C concentration), but plasma lathosterol, campesterol and sitosterol expressed per plasma cholesterol increased.

CONCLUSIONS

The lathosterol-to-cholesterol plasma ratio predicted the plasma cholesterol response to PS feeding. The highest plasma lathosterol concentration during the control phase was associated with a lack of response of plasma cholesterol during the PS treatment period. Consequently, cholesterol synthesis in non-responders to dietary PS being elevated in the control phase indicates these cases resist to further synthesis rise, whereas responders to dietary PS, having in the control phase synthesis values lower than non-responders, expand synthesis on alimentary PS. Responders absorb more PS than non-responders, likely resulting from responders delivering into the intestinal lumen less endogenous cholesterol than non-responders do, thus facilitating greater intestinal absorption of PS shown as increased plasma PS concentration.

The association of cytochrome 7A1 and ATP-binding cassette G8 genotypes with type 2 diabetes among Jordanian patients

OBJECTIVES

Increased cholesterol levels were found to be associated with diabetes mellitus type II (DM2). The cholesterol is metabolized by cytochrome 7A1 (CYP7A1) and transported in the intestine by ATP-binding cassette G8 (ABCG8). Genetic variants in CYP7A1 and ABCG8 genes can affect the cholesterol levels. The aim of this study is to compare the frequency of CYP7A1 rs3808607 and ABCG8 rs11887534 and rs4148217 genotypes between healthy and DM2 subjects from Jordanian population.

METHODS

A total of 117 DM2 patients and 100 healthy controls, of Jordanian Arabic origin, were genotyped for CYP7A1 rs3808607 and ABCG8 rs11887534 and rs4148217 genetic variants using polymerase chain reaction (PCR) followed by restriction fragment length polymorphism technique.

RESULTS

The study showed that homozygosity of rs3808607 (A-204C) genotype in CYP7A1 was significantly higher in DM2 patients (ANOVA, p<0.05) with an odd ratio of 2.66, but rs11887534 (G55C) and rs4148217 (C1199A) genetic polymorphisms in ABCG8 were found in comparable frequencies in both healthy and DM2 subjects.

CONCLUSIONS

The results of this study indicate that CYP7A1 rs3808607 genetic polymorphism is associated with DM2. Further clinical studies are required to confirm this finding among DM2 patients of Jordanian origin.

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.

Phytosterols, Cholesterol Control, and Cardiovascular Disease

The use of phytosterols (or plant sterols) for the control of plasma cholesterol concentrations has recently gained traction because their efficacy is acknowledged by scientific authorities and leading guidelines. Phytosterols, marketed as supplements or functional foods, are formally classified as food in the European Union, are freely available for purchase, and are frequently used without any health professional advice; therefore, they are often self-prescribed, either inappropriately or in situations in which no significant advantage can be obtained. For this reason, a panel of experts with diverse medical and scientific backgrounds was convened by NFI—Nutrition Foundation of Italy—to critically evaluate and summarize the literature available on the topic, with the goal of providing medical doctors and all health professionals useful information to actively govern the use of phytosterols in the context of plasma cholesterol control. Some practical indications to help professionals identify subjects who will most likely benefit from the use of these products, optimizing the therapeutic outcomes, are also provided. The panel concluded that the use of phytosterols as supplements or functional foods to control Low Density Lipoprotein (LDL) cholesterol levels should be preceded by the assessment of some relevant individual characteristics: cardiovascular risk, lipid profile, correct understanding of how to use these products, and willingness to pay for the treatment.

Markers of cholesterol synthesis to cholesterol absorption across the spectrum of non-dialysis CKD: An observational study

In dialysis patients, cholesterol-lowering therapy with statins is less effective than in other high-risk patients. This may be explained by a shift from cholesterol synthesis toward cholesterol absorption. In line, markers of cholesterol absorption-such as campesterol-better predict atherosclerotic cardiovascular events than markers of cholesterol synthesis-such as lathosterol-in dialysis patients. To test the association between markers of cholesterol absorption such as campesterol-and markers of cholesterol synthesis-such as lathosterol-against cardiovascular events in non-dialysis CKD patients. Altogether 251 patients those not on lipid-lowering agents were followed annually for the composite endpoint atherosclerotic cardiovascular disease (ASCVD) and all-cause death. During follow-up of 5.2 ± 2.1 years, 61 participants reached the primary endpoint atherosclerotic cardiovascular disease/all-cause death [ASCVD/D], 47 participants suffered from ASCVD, and 46 participants died. In univariate Cox regression analysis, campesterol/lathosterol ratio did not significantly predict ASCVD/D (HR 0.643; 0.358-1.155; 3rd vs. 1st tertile), all-cause death (HR 1.309; 0.604-2.838; 3rd vs. 1st tertile) nor ASCVD (HR 0.589; 0.311-1.118; 3rd vs. 1st tertile). We did not observe a shift from cholesterol synthesis to cholesterol absorption across the spectrum of non-dialysis CKD. Campesterol/lathosterol ratio did not predict future ASCVD or all-cause death in non-dialysis CKD.

Associations between Circulating Markers of Cholesterol Homeostasis and Macrovascular Events among Patients Undergoing Hemodialysis

Current strategies targeting serum cholesterol bring limited benefits to mortality and macrovascular events prevention among hemodialysis patients. Direct measurements and analysis on circulating markers of cholesterol homeostasis could be promising solutions to this bottleneck. We prospectively enrolled 90 maintenance hemodialysis patients and 9 healthy controls in 2019 for 1 year. We measured circulating desmosterol and lathosterol as markers for cholesterol synthesis and campesterol and sitosterol for cholesterol absorption. At baseline, hemodialysis patients showed higher levels of campesterol (p = 0.023) compared to healthy controls. During follow-up, we identified 14 (15.4%) patients who experienced macrovascular events. Comparisons of cholesterol homeostasis markers between cohorts with and without macrovascular events showed no significant differences in markers of cholesterol synthesis or absorption. Using logistic regression analysis, the odds ratio was not statistically significant for the prediction of macrovascular events after full-adjusting for age, sex, diabetes, serum albumin, cholesterol, and triglyceride. We concluded that hemodialysis patients demonstrated higher level of cholesterols absorption, indicated by circulating campesterol compared to healthy subjects. Markers for cholesterol homeostasis were not significantly associated with macrovascular events during a 1-year follow-up. Our results shed light on the novel therapeutic target of modulating cholesterol absorption in HD patients.

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.

Gut microbes from the phylogenetically diverse genus Eubacterium and their various contributions to gut health

Over the last two decades our understanding of the gut microbiota and its contribution to health and disease has been transformed. Among a new 'generation' of potentially beneficial microbes to have been recognized are members of the genus Eubacterium, who form a part of the core human gut microbiome. The genus consists of phylogenetically, and quite frequently phenotypically, diverse species, making Eubacterium a taxonomically unique and challenging genus. Several members of the genus produce butyrate, which plays a critical role in energy homeostasis, colonic motility, immunomodulation and suppression of inflammation in the gut. Eubacterium spp. also carry out bile acid and cholesterol transformations in the gut, thereby contributing to their homeostasis. Gut dysbiosis and a consequently modified representation of Eubacterium spp. in the gut, have been linked with various human disease states. This review provides an overview of Eubacterium species from a phylogenetic perspective, describes how they alter with diet and age and summarizes its association with the human gut and various health conditions.

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.

Safety of the extension of use of plant sterol esters as a novel food pursuant to Regulation (EU) 2015/2283

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on the safety of an extension of use of the novel food 'plant sterol esters' when added to vegetable fat spreads and to liquid vegetable fat-based emulsions for cooking and baking purposes pursuant to Regulation (EU) 2015/2283. Member States expressed concerns in relation to plant sterol oxidation products (POP) and consumption by non-target population groups. The median (0.5%) and P90 (2.28%) value of the oxidation rates of plant sterols determined by a wide range of cooking experiments were used together with exposure estimates for plant sterol when added and cooked with vegetable fat spreads and liquids. The no-observed adverse effect level (NOAEL) of a subchronic rat study and an applied default uncertainty factor of 200 served to derive levels (i.e. 0.64 mg POP/kg body weight (bw) per day) considered safe for humans. This safe level of exposure would be exceeded at the P95 by all age groups when considering the P90 oxidation rate and using EFSA's comprehensive food consumption database for assessing the potential exposure. When considering the median oxidation rate, the safe level of 0.64 mg POP/kg bw per day would be exceeded at the highest P95 intake estimates in children below 9 years of age. When considering an intake of the maximum authorised use level of 3 g plant sterols/person per day and oxidation rates of 0.5% and 2.28%, the resulting daily POP intakes per kg bw by an adult weighing 70 kg would be 0.21 and 0.98 mg/kg bw per day, respectively, the latter value exceeding 0.64 mg/kg bw per day. The Panel concludes that the safety of the intended extension of use of plant sterol esters under the proposed conditions of use has not been established.

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.

Methodological Aspects of Phytosterol Measurements in Biological Samples

Phytosterol measurement has gained a lot of interest during the last two decades after foods and supplements with added 4-desmethyl phytosterols were recognized and used as effective and safe non-pharmacologic hypocholesterolemic agents, and also after the mechanisms of intestinal absorption and hepatic excretion of sterols were unraveled. In addition, the wide use of serum phytosterols as biomarkers of cholesterol absorption has increased the interest in their measurement. In this review, the basic methods are discussed without going into details of the practical operations. The analysis includes first lipid extraction and saponification from various biologic matrices such as serum/plasma, feces, or tissues, after which the individual sterols are separated by adsorption chromatography (gas-liquid or liquid or high performance liquid chromatography) based on the polarity of the various sterols. We also deal with some specific aspects of phytosterol measurements in biological samples such as the need of harmonization of their analysis in biological samples, the discrepancies in the results of sitosterol and campesterol concentrations between different studies, and what is known about their biological day-to-day fluctuation. Phytosterols have a remarkable role in human health, so that their complicated and time consuming measurements call attention to routine ways of standardization between the sterol research laboratories.

Roles of Achieved Levels of Low-Density Lipoprotein Cholesterol and High-Sensitivity C-Reactive Protein on Cardiovascular Outcome in Statin Therapy

In statin therapy, the prognostic role of achieved low-density lipoprotein cholesterol (LDL-C) and high-sensitivity C-reactive protein (hsCRP) in cardiovascular outcomes has not been fully elucidated. A total of 4,803 percutaneous coronary intervention (PCI)-naïve patients who prescribed moderate intensity of statin therapy were followed up. Total and each component of major adverse cardiovascular events (MACE) according to LDL-C and hsCRP quartiles were compared. The incidence of 5-year total MACEs in the highest quartile group according to the followed-up hsCRP was higher than that in the lowest quartile (hazard ratio (HR) = 2.16, p < 0.001). However, there was no difference between the highest and lowest quartiles of the achieved LDL-C (HR = 0.95, p = 0.743). After adjustment of potential confounders, the incidence of total death, de novo PCI, atrial fibrillation, and heart failure in the highest quartile of followed-up hsCRP, was higher than that in the lowest quartile (all p < 0.05). However, other components except for de novo PCI in the highest quartile by achieved LDL-C was not different to that in the lowest quartile. These results suggest that followed-up hsCRP can be more useful for predicting future cardiovascular outcome than achieved LDL-C in PCI-naïve patients with statin therapy.

Fetal androgen exposure is a determinant of adult male metabolic health

Androgen signalling is a critical driver of male development. Fetal steroid signalling can be dysregulated by a range of environmental insults and clinical conditions. We hypothesised that poor adult male health was partially attributable to aberrant androgen exposure during development. Testosterone was directly administered to developing male ovine fetuses to model excess prenatal androgenic overexposure associated with conditions such as polycystic ovary syndrome (PCOS). Such in utero androgen excess recreated the dyslipidaemia and hormonal profile observed in sons of PCOS patients. 1,084 of 15,134 and 408 of 2,766 quantifiable genes and proteins respectively, were altered in the liver during adolescence, attributable to fetal androgen excess. Furthermore, prenatal androgen excess predisposed to adolescent development of an intrahepatic cholestasis-like condition with attendant hypercholesterolaemia and an emergent pro-fibrotic, pro-oxidative stress gene and protein expression profile evident in both liver and circulation. We conclude that prenatal androgen excess is a previously unrecognised determinant of lifelong male metabolic health.

Cardiovascular Disease Prevention: The Earlier the Better? A Review of Plant Sterol Metabolism and Implications of Childhood Supplementation

Atherosclerosis is the underlying cause of major cardiovascular events. The development of atherosclerotic plaques begins early in life, indicating that dietary interventions in childhood might be more effective at preventing cardiovascular disease (CVD) than treating established CVD in adulthood. Although plant sterols are considered safe and consistently effective in lowering plasma cholesterol, the health effects of early-life supplementation are unclear. Studies suggest there is an age-dependent effect on plant sterol metabolism: at a younger age, plant sterol absorption might be increased, while esterification and elimination might be decreased. Worryingly, the introduction of low-cholesterol diets in childhood may unintentionally favor a higher intake of plant sterols. Although CVD prevention should start as early as possible, more studies are needed to better elucidate the long-term effects of plant sterol accumulation and its implication on child development.

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.

Phytosterol containing diet increases plasma and whole body concentration of phytosterols in apoE-KO but not in LDLR-KO mice

Phytosterol metabolism is unknown in the hypercholesterolemia of genetic origin. We investigated the metabolism of phytosterols in a cholesterol-free, phytosterol-containing standard diet in hypercholesterolemic mice knockouts for low density lipoprotein receptor (LDLR) and apolipoprotein E (apoE) mice compared to wild-type mice (controls). Phytosterols were measured in mice tissues by GCMS. ApoE-KO mice absorbed less phytosterols than LDLR-KO and the latter absorbed less phytosterols than control mice, because the intestinal campesterol content was low in both KO mice, and sitosterol was low in the intestine in apoE-KO mice as compared to LDLR-KO mice. Although the diet contained nine times more sitosterol than campesterol, the concentration of sitosterol was lower than that of campesterol in plasma in LDLR-KO, and in the liver in controls and in LDLR-KO, but only in apoE-KO. On the other hand, in the intestine sitosterol was higher than campesterol in controls, and in LDLR-KO but with a tendency only in apoE-KO. Because of the high dietary supply of sitosterol, sitosterol was better taken up by the intestine than campesterol, but the amount of sitosterol was lower than that of campesterol in the liver, while in the whole body the amounts of these phytosterols do not differ from each other. Therefore, via intestinal lymph less sitosterol than campesterol was transferred to the body. However, as compared to controls, in apoE-KO mice, but not in LDLR-KO mice, the increase in campesterol and sitosterol in plasma and in the whole body indicating that apoE-KO mice have a marked defect in the elimination of both phytosterols from the body.

A Newly Integrated Model for Intestinal Cholesterol Absorption and Efflux Reappraises How Plant Sterol Intake Reduces Circulating Cholesterol Levels

Cholesterol homeostasis is maintained through a balance of de novo synthesis, intestinal absorption, and excretion from the gut. The small intestine contributes to cholesterol homeostasis by absorbing and excreting it, the latter of which is referred to as trans-intestinal cholesterol efflux (TICE). Because the excretion efficiency of endogenous cholesterol is inversely associated with the development of atherosclerosis, TICE provides an attractive therapeutic target. Thus, elucidation of the mechanism is warranted. We have shown that intestinal cholesterol absorption and TICE are inversely correlated in intestinal perfusion experiments in mice. In this review, we summarized 28 paired data sets for absorption efficiency and fecal neutral sterol excretion, a surrogate marker of TICE, obtained from 13 available publications in a figure, demonstrating the inverse correlation were nearly consistent with the assumption. We then offer a bidirectional flux model that accommodates absorption and TICE occurring in the same segment. In this model, the brush border membrane (BBM) of intestinal epithelial cells stands as the dividing ridge for cholesterol fluxes, making the opposite fluxes competitive and being coordinated by shared BBM-localized transporters, ATP-binding cassette G5/G8 and Niemann-Pick C1-like 1. Furthermore, the idea is applied to address how excess plant sterol/stanol (PS) intake reduces circulating cholesterol level, because the mechanism is still unclear. We propose that unabsorbable PS repeatedly shuttles between the BBM and lumen and promotes concomitant cholesterol efflux. Additionally, PSs, which are chemically analogous to cholesterol, may disturb the trafficking machineries that transport cholesterol to the cell interior.

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.

Microbial impact on cholesterol and bile acid metabolism: current status and future prospects

Recently, the gut microbiota has emerged as a crucial factor that influences cholesterol metabolism. Ever since, significant interest has been shown in investigating these host-microbiome interactions to uncover microbiome-mediated functions on cholesterol and bile acid (BA) metabolism. Indeed, changes in gut microbiota composition and, hence, its derived metabolites have been previously reported to subsequently impact the metabolic processes and have been linked to several diseases. In this context, associations between a disrupted gut microbiome, impaired BA metabolism, and cholesterol dysregulation have been highlighted. Extensive advances in metagenomic and metabolomic studies in this field have allowed us to further our understanding of the role of intestinal bacteria in metabolic health and disease. However, only a few have provided mechanistic insights into their impact on cholesterol metabolism. Identifying the myriad functions and interactions of these bacteria to maintain cholesterol homeostasis remain an important challenge in such a field of research. In this review, we discuss the impact of gut microbiota on cholesterol metabolism, its association with disease settings, and the potential of modulating gut microbiota as a promising therapeutic target to lower hypercholesterolemia.

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.

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.

Walnut Consumption Alters the Gastrointestinal Microbiota, Microbially Derived Secondary Bile Acids, and Health Markers in Healthy Adults: A Randomized Controlled Trial

Background

Epidemiologic data suggest that diets rich in nuts have beneficial health effects, including reducing total and cause-specific mortality from cancer and heart disease. Although there is accumulating preclinical evidence that walnuts beneficially affect the gastrointestinal microbiota and gut and metabolic health, these relations have not been investigated in humans.

Objective

We aimed to assess the impact of walnut consumption on the human gastrointestinal microbiota and metabolic markers of health.

Methods

A controlled-feeding, randomized crossover study was undertaken in healthy men and women [n = 18; mean age = 53.1 y; body mass index (kg/m2): 28.8]. Study participants received isocaloric diets containing 0 or 42 g walnuts/d for two 3-wk periods, with a 1-wk washout between diet periods. Fecal and blood samples were collected at baseline and at the end of each period to assess secondary outcomes of the study, including effects of walnut consumption on fecal microbiota and bile acids and metabolic markers of health.

Results

Compared with after the control period, walnut consumption resulted in a 49-160% higher relative abundance of Faecalibacterium, Clostridium, Dialister, and Roseburia and 16-38% lower relative abundances of Ruminococcus, Dorea, Oscillospira, and Bifidobacterium (P < 0.05). Fecal secondary bile acids, deoxycholic acid and lithocholic acid, were 25% and 45% lower, respectively, after the walnut treatment compared with the control treatment (P < 0.05). Serum LDL cholesterol and the noncholesterol sterol campesterol concentrations were 7% and 6% lower, respectively, after walnut consumption compared with after the control treatment (P < 0.01).

Conclusion

Walnut consumption affected the composition and function of the human gastrointestinal microbiota, increasing the relative abundances of Firmicutes species in butyrate-producing Clostridium clusters XIVa and IV, including Faecalibacterium and Roseburia, and reducing microbially derived, proinflammatory secondary bile acids and LDL cholesterol. These results suggest that the gastrointestinal microbiota may contribute to the underlying mechanisms of the beneficial health effects of walnut consumption. This trial was registered at www.clinicaltrials.gov as NCT01832909.

The effects of vitamin E or lipoic acid supplementation on oxyphytosterols in subjects with elevated oxidative stress: a randomized trial

Despite increased serum plant sterol concentrations after consumption of plant sterol enriched margarines, plasma oxyphytosterol concentrations were not increased in healthy subjects. Here, we assessed plasma oxyphytosterol concentrations and whether they are affected by antioxidants in subjects with elevated oxidative stress. Twenty subjects with impaired glucose tolerance (IGT) or type 2 diabetes (DM2) consumed for 4 weeks placebo, vitamin E (804 mg/d) or lipoic acid capsules (600 mg/d). Plasma and blood cell oxyphytosterol and oxycholesterol concentrations were determined in butylated hydroxytoluene-enriched EDTA plasma via GC-MS. Also, markers reflecting oxidative stress and antioxidant capacity were measured. Plasma oxycampesterol and oxysitosterol concentrations were 122% and 83% higher in IGT or DM2 subjects than in healthy subjects, as determined in an earlier study. Vitamin E or lipoic acid supplementation did not reduce plasma oxyphytosterol and oxycholesterol concentrations, or other markers reflecting oxidative stress or antioxidative capacity. Concentrations of different oxyphytosterols correlated within plasma, and within red blood cells and platelets. However, plasma and blood cell oxyphytosterol levels did not correlate. Although plasma oxyphytosterol concentrations are higher in IGT or DM2 subjects than in healthy subjects, 4-weeks vitamin E or lipoic acid supplementation does not lower plasma oxycholesterol or oxyphytosterol concentrations.

The association between hypercholesterolemia and sitosterolemia, and report of a sitosterolemia kindred

BACKGROUND

Sitosterolemia is associated with increases in intestinal sterol absorption, low-density lipoprotein cholesterol (LDL-C), and cardiovascular disease risk.

OBJECTIVE

We examined the relationship between hypercholesterolemia and sitosterolemia in a large population and report a new sitosterolemia case.

METHODS

Plasma sterol concentrations were measured by gas chromatography/mass spectrometry, and LDL-C by direct assay.

RESULTS

Of 207,926 subjects tested, 4.3% had LDL-C ≥190 mg/dL. Plasma β-sitosterol concentrations ≥8.0 mg/L (99th percentile) were found in 4.3% of these subjects vs 0.72% with LDL-C <130 mg/dL. Among all subjects, 0.050% had β-sitosterol levels ≥15.0 mg/L, consistent with sitosterolemia, while among those with LDL-C ≥190 mg/dL, 0.334% had this rare disorder. A 13-year-old boy with the highest LDL-C (679 mg/dL) of all subjects had planar xanthomas and a β-sitosterol level of 53.5 mg/L (normal <3.3 mg/L). He was a compound heterozygote for 2 ABCG8 mutations (p.N409D and an intron 11+2T>A splice site mutation). On a low-cholesterol and plant-sterol diet, his LDL-C decreased to 485 mg/dL (-29%) and β-sitosterol to 44.6 mg/L (-27%). On atorvastatin 20 mg/d, his LDL-C decreased to 299 mg/dL (-38%). With added ezetimibe 10 mg/d, his LDL-C normalized to 60 mg/dL (-80% further decrease); and his β-sitosterol decreased to 14.1 mg/L (-68% further decrease).

CONCLUSIONS

Our data indicate that about 4% of subjects with LDL-C concentrations ≥190 mg/dL have plasma β-sitosterol concentrations above the 99th percentile and about 0.3% have concentrations consistent with sitosterolemia. Therefore, this diagnosis should be considered in such patients.

Endogenous Cholesterol Excretion Is Negatively Associated With Carotid Intima-Media Thickness in Humans

OBJECTIVE

Epidemiological studies strongly suggest that lipid factors independent of low-density lipoprotein cholesterol contribute significantly to cardiovascular disease risk. Because circulating lipoproteins comprise only a small fraction of total body cholesterol, the mobilization and excretion of cholesterol from plasma and tissue pools may be an important determinant of cardiovascular disease risk. Our hypothesis is that fecal excretion of endogenous cholesterol is protective against atherosclerosis.

APPROACH AND RESULTS

Cholesterol metabolism and carotid intima-media thickness were quantitated in 86 nondiabetic adults. Plasma cholesterol was labeled by intravenous infusion of cholesterol-d₇ solubilized in a lipid emulsion and dietary cholesterol by cholesterol-d₅ and the nonabsorbable stool marker sitostanol-d₄. Plasma and stool samples were collected while subjects consumed a cholesterol- and phytosterol-controlled metabolic kitchen diet and were analyzed by mass spectrometry. Carotid intima-media thickness was negatively correlated with fecal excretion of endogenous cholesterol (r=-0.426; P<0.0001), total cholesterol (r=-0.472; P≤0.0001), and daily percent excretion of cholesterol from the rapidly mixing cholesterol pool (r=-0.343; P=0.0012) and was positively correlated with percent cholesterol absorption (r=+0.279; P=0.0092). In a linear regression model controlling for age, sex, systolic blood pressure, hemoglobin A1c, low-density lipoprotein, high-density lipoprotein cholesterol, and statin drug use, fecal excretion of endogenous cholesterol remained significant (P=0.0008).

CONCLUSIONS

Excretion of endogenous cholesterol is strongly, independently, and negatively associated with carotid intima-media thickness. The reverse cholesterol transport pathway comprising the intestine and the rapidly mixing plasma, and tissue cholesterol pool could be an unrecognized determinant of cardiovascular disease risk not reflected in circulating lipoproteins. Further work is needed to relate measures of reverse cholesterol transport to atherosclerotic disease.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01603758.