Increased Cholesterol Synthesis Research Articles

Probiotic Lactobacillus rhamnosus GG and Aloe vera gel improve lipid profiles in hypercholesterolemic rats

ObjectiveThe effects of Lactobacillus rhamnosus GG (LGG) and Aloe vera (AV) gel on lipid profiles in rats with induced hypercholesterolemia were studied. MethodsFive treatment groups of rats (n = 7) were the fed experimental diets: a normal control diet, a hypercholesterolemic diet (HD), HD + LGG, HD + AV gel, and HD + LGG + AV gel. ResultsSupplementation with LGG decreased serum total cholesterol by 32%; however, in combination with AV, the decrease was 43%. The decreases in triacylglycerol levels in the HD + LGG, HD + AV, and HD + LGG + AV groups were 41%, 23% and 45%, respectively. High-density lipoprotein increased by 12% in the HD + LGG + AV group, whereas very low-density and low-density lipoprotein values decreased by 45% and 30%, respectively. The atherogenic index in the HD + LGG + AV group decreased to 2.45 from 4.77 in the HD + LGG group. Furthermore, fecal Lactobacillus species counts increased significantly when LGG was fed in combination with the AV gel. The oral administration of LGG fermented milk alone or in combination with the AV gel increased cholesterol synthesis (3-hydroxy-3-methylglutaryl coenzyme A reductase expression) and absorption (low-density lipoprotein receptor expression), whereas cholesterol 7α-hydroxylase mRNA expression levels were lower in the HD + LGG and HD + LGG + AV groups compared with the control HD group. ConclusionThe combination of LGG and AV gel may have a therapeutic potential to decrease cholesterol levels and the risk of cardiovascular diseases.

Colesevelam

Colesevelam

Hepatitis C virus selectively perturbs the distal cholesterol synthesis pathway in a genotype-specific manner

Hepatitis C virus (HCV) subverts host cholesterol metabolism for key processes in its lifecycle. How this interference results in the frequently observed, genotype-dependent clinical sequelae of hypocholesterolemia, hepatic steatosis, and insulin resistance (IR) remains incompletely understood. Hypocholesterolemia typically resolves after sustained viral response (SVR), implicating viral interference in host lipid metabolism. Using a targeted cholesterol metabolomic platform we evaluated paired HCV genotype 2 (G2) and G3 patient sera for changes in in vivo HCV sterol pathway metabolites. We compared HCV genotypic differences in baseline metabolites and following antiviral treatment to assess whether sterol perturbation resolved after HCV eradication. We linked these metabolites to IR and urine oxidative stress markers. In paired sera from HCV G2 (n = 13) and G3 (n = 20) patients, baseline sterol levels were lower in G3 than G2 for distal metabolites (7-dehyrocholesterol (7DHC) 0.017 versus 0.023 mg/dL; P(adj) = 0.0524, cholesterol 140.9 versus 178.7 mg/dL; P(adj) = 0.0242) but not the proximal metabolite lanosterol. In HCV G3, SVR resulted in increased levels of distal metabolites (cholesterol [Δ55.2 mg/dL; P(adj) = 0.0015], 7DHC [Δ0.0075 mg/dL; P(adj) = 0.0026], lathosterol [Δ0.0430 mg/dL P(adj) = 0.0405]). In contrast, lanosterol was unchanged after SVR (P = 0.9515). HCV G3, but not G2, selectively interferes with the late cholesterol synthesis pathway, evidenced by lower distal sterol metabolites and preserved lanosterol levels. This distal interference resolves with SVR. Normal lanosterol levels provide a signal for the continued proteolysis of 3-hydroxyl-3-methylglutaryl coenzyme A reductase, which may undermine other host responses to increase cholesterol synthesis. These data may provide a hypothesis to explain why hypocholesterolemia persists in chronic HCV infection, particularly in HCV G3, and is not overcome by host cholesterol compensatory mechanisms.

MicroRNAs in Vascular and Metabolic Disease

Recent findings demonstrated the importance of microRNAs (miRNAs) in the vasculature and the orchestration of lipid metabolism and glucose homeostasis. MiRNA networks represent an additional layer of regulation for gene expression that absorbs perturbations and ensures the robustness of biological systems. This function is very elegantly demonstrated in cholesterol metabolism where miRNAs reducing cellular cholesterol export are embedded in the very same genes that increase cholesterol synthesis. Often their alteration does not affect normal development but changes under stress conditions and in disease. A detailed understanding of the molecular and cellular mechanisms of miRNA-mediated effects on metabolism and vascular pathophysiology could pave the way for the development of novel diagnostic markers and therapeutic approaches. In the first part of this review, we summarize the role of miRNAs in vascular and metabolic diseases and explore potential confounding effects by platelet miRNAs in preclinical models of cardiovascular disease. In the second part, we discuss experimental strategies for miRNA target identification and the challenges in attributing miRNA effects to specific cell types and single targets.

Small Interfering RNA against Transcription Factor STAT6 Leads to Increased Cholesterol Synthesis in Lung Cancer Cell Lines

STAT6 transcription factor has become a potential molecule for therapeutic intervention because it regulates broad range of cellular processes in a large variety of cell types. Although some target genes and interacting partners of STAT6 have been identified, its exact mechanism of action needs to be elucidated. In this study, we sought to further characterize the molecular interactions, networks, and functions of STAT6 by profiling the mRNA expression of STAT6 silenced human lung cells (NCI-H460) using microarrays. Our analysis revealed 273 differentially expressed genes after STAT6 silencing. Analysis of the gene expression data with Ingenuity Pathway Analysis (IPA) software revealed Gene expression, Cell death, Lipid metabolism as the functions associated with highest rated network. Cholesterol biosynthesis was among the most enriched pathways in IPA as well as in PANTHER analysis. These results have been validated by real-time PCR and cholesterol assay using scrambled siRNA as a negative control. Similar findings were also observed with human type II pulmonary alveolar epithelial cells, A549. In the present study we have, for the first time, shown the inverse relationship of STAT6 with the cholesterol biosynthesis in lung cancer cells. The present findings are potentially significant to advance the understanding and design of therapeutics for the pathological conditions where both STAT6 and cholesterol biosynthesis are implicated viz. asthma, atherosclerosis etc.

The Chylomicron: Relationship to Atherosclerosis

The B-containing lipoproteins are the transporters of cholesterol, and the evidence suggests that the apo B48-containing postprandial chylomicron particles and the triglyceride-rich very low density lipoprotein (VLDL) particles play an important part in the development of the plaque both directly and indirectly by their impact on LDL composition. The ratio of dietary to synthesised cholesterol is variable but tightly regulated: hence intervention with diet at best reduces serum cholesterol by <20% andusually <10%. Statins are the mainstay of cholesterol reduction therapy, but they increase cholesterol absorption, an example of the relationship between synthesis and absorption. Inhibition of cholesterol absorption with Ezetimibe, an inhibitor of Niemann Pick C1-like 1 (NPC1-L1), the major regulator of cholesterol absorption, increases cholesterol synthesis and hence the value of adding an inhibitor of cholesterol absorption to an inhibitor of cholesterol synthesis. Apo B48, the structural protein of the chylomicron particle, is synthesised in abundance so that the release of these particles is dependent on the amount of cholesterol and triglyceride available in the intestine. This paper will discuss cholesterol absorption and synthesis, chylomicron formation, and the effect of postprandial lipoproteins on factors involved in atherosclerosis.

Low HDL-C can predict prognosis of patients with coronary heart disease who underwent PCI in Shanxi

causative factor for type 2 diabetes and is associated with hypertension. We have recently reported abnormal plasma lipid levels in Sprague–Dawley (SD) rats treated chronically with MG. The aim of this study was to explore the possible mechanism(s) of MG-induced dyslipidemia. MG (60 mg/kg/day) or 0.9% saline was administered to 12-week-old male SD rats by continuous infusion with a minipump for 28 days, and thereafter the plasma, liver and adipose tissue were collected. We also used cultured 3T3-L1 adipocytes for molecular studies. We performed Oil-Red O and hemotoxylin-eosin staining, ELISA, western blotting and quantitative PCR. In the liver of rats treated chronically with MG, there was increased protein expression of sterol regulatory element binding protein-2 (SREBP-2), 3-hydroxy 3 methyl glutaryl coenzymeA (HMG-CoA) reductase and microsomal transfer protein (MTP), with no change in SREBP-1c. In the adipose tissue, MG treated rats showed enlarged abdominal adipocytes, and increased protein expression and/or mRNA of CCAAT-enhancer binding protein (C/EBP)α, C/EBPβ and TNFα, with no significant change in leptin and lipoprotein lipase levels. The effects of MG were attenuated by alagebrium, a MG scavenger and an advanced glycation endproducts breaker. The findings in adipose tissue were confirmed in 3T3-L1 cells. Our results indicate that the increase in plasma cholesterol and triglycerides by MG may be due to increased activity of hepatic SREBP-2 and HMG-CoA reductase, and the subsequent increased cholesterol synthesis; and due to increased activity of MTP and the resultant increased VLDL synthesis. The increase in plasma free fatty acids may be due to up regulated gene expression of TNFα and the resultant decreased free fatty acids uptake and increased lipolysis in adipocytes.

Plant stanol esters lower LDL cholesterol level in statin-treated subjects with type 1 diabetes by interfering the absorption and synthesis of cholesterol

Objective We investigated the effects of plant stanol esters (STAEST) on serum cholesterol and lipoprotein lipid concentrations and serum non-cholesterol sterols in patients with type 1 diabetes who were on statin treatment. Methods In a randomized, double-blind, parallel study the intervention group ( n = 12) consumed vegetable oil-based spread enriched with STAEST (3.0 g/d of plant stanols), and the control group ( n = 12) consumed the same spread containing no added plant stanols for 4 weeks. Results Serum total, LDL and non-HDL cholesterol concentrations were decreased by 9.6, 16.4 and 15.3% compared with the baseline concentrations in the STAEST group ( P < 0.05 for all). The respective reductions were 7.8, 14.8 and 12.2% compared with the controls ( P < 0.05 for all). No effects on HDL cholesterol or serum triglyceride concentrations were found. The STAEST consumption significantly decreased serum plant sterol concentrations and the ratios to cholesterol by 30–32 and 25–27% ( P < 0.05 for all) compared with the baseline levels, respectively. Cholesterol synthesis markers were not increased in the STAEST group, but serum lathosterol to campesterol ratio was significantly increased by 57% compared with the baseline levels indicating increased cholesterol synthesis at least to some extent in compensation for decreased cholesterol absorption. However, cholesterol homeostasis, intact at baseline and in the control group also during the intervention was lost in the STAEST group. Conclusion STAEST significantly decreased serum total, LDL and non-HDL cholesterol concentrations and thus offers an additional benefit to cholesterol lowering in patients with type 1 diabetes who are on statin treatment.

Reverse cholesterol transport is elevated in carboxyl ester lipase‐knockout mice

Mechanisms to increase reverse cholesterol transport (RCT) and biliary sterol disposal are currently sought to prevent atherosclerosis. Previous work with HepG2 cells and primary hepatocytes showed that carboxyl ester lipase (CEL), a broad-spectrum lipase secreted by pancreas and liver, plays an important role in hydrolysis of high-density lipoprotein (HDL) cholesteryl esters (CEs) after selective uptake by hepatocytes. The effect of CEL on RCT of HDL cholesterol was assessed by measuring biliary and fecal disposal of radiolabeled HDL-CE in control and Cel(-/-) mice. Radiolabeled CE was increased 3-fold in hepatic bile of Cel(-/-) mice, and the mass of CE in gall bladder bile was elevated. Total radiolabeled transport from plasma to hepatic bile was more rapid in Cel(-/-) mice. Fecal disposal of radiolabel from HDL-CE, as well as total sterol mass, was markedly elevated for Cel(-/-) mice, primarily due to more CE. RCT of macrophage CE was also increased in Cel(-/-) mice, as measured by excretion of radiolabel from injected J774 cells. Increased sterol loss was compensated by increased cholesterol synthesis in Cel(-/-) mice. Together, the data demonstrate significantly increased RCT in the absence of CEL and suggest a novel mechanism by which to manipulate plasma cholesterol flux.

Increasing cholesterol synthesis in 7-dehydrosterol reductase (DHCR7) deficient mouse models through gene transfer

Smith–Lemli–Opitz syndrome (SLOS) is caused by deficiency in the terminal step of cholesterol biosynthesis: the conversion of 7-dehydrocholesterol (7DHC) to cholesterol (C), catalyzed by 7-dehydrocholesterol reductase (DHCR7). This disorder exhibits several phenotypic traits including dysmorphia and mental retardation with a broad range of severity. There are few proven treatment options. That most commonly used is a high cholesterol diet that seems to enhance the quality of life and improve behavioral characteristics of patients, although these positive effects are controversial. The goal of our study was to investigate the possibility of restoring DHCR7 activity by gene transfer. We constructed an adeno-associated virus (AAV) vector containing the DHCR7 gene. After we infused this vector into affected mice, the introduced DHCR7 gene could be identified in liver, mRNA was expressed and a functional enzyme was produced. Evidence of functionality came from the ability to partially normalize the serum ratio of 7DHC/C in treated animals, apparently by increasing cholesterol production with concomitant decrease in 7DHC precursor. By 5 weeks after treatment the mean ratio (for 7 animals) had fallen to 0.05 while the ratio for untreated littermate controls had risen to 0.14. This provides proof of principle that gene transfer can ameliorate the genetic defect causing SLOS and provides a new experimental tool for studying the pathogenesis of this disease. If effective in humans, it might also offer a possible alternative to exogenous cholesterol therapy. However, it would not offer a complete cure for the disorder as many of the negative implications of defective synthesis are already established during prenatal development.

Non-cholesterol sterols in different forms of primary hyperlipemias

Background and AimsWe investigated the behaviour of non-cholesterol sterols, surrogate markers of cholesterol absorption (campesterol and sitosterol) and synthesis (lathosterol), in primary hyperlipemias. Methods and resultsWe studied 53 patients with polygenic hypercholesterolemia (PH), 38 patients with familial combined hyperlipemia (FCH), and 19 age- and sex-matched healthy control subjects. In all participants, plasma sitosterol, campesterol and lathosterol were determined by gas chromatography coupled to mass spectrometry. To correct for the effect of plasma lipid levels, non-cholesterol sterol concentrations were adjusted for plasma cholesterol (102 μmol/mmol cholesterol). Patients with FCH were more frequently men, and had higher body mass index (BMI), fasting glucose, insulin and HOMA-IR. Lathosterol was higher in FCH than in pH or controls (p < 0.05). Campesterol was significantly lower in FCH (p < 0.05), while no differences were found between pH and controls. Sitosterol displayed higher values in pH compared to FCH (p < 0.001) and controls (p < 0.05). Spearman’s rank correlations showed positive correlations of lathosterol with BMI, waist circumference, HOMA-IR, triglycerides, apoprotein B, and a negative one with HDL-cholesterol. Sitosterol had a negative correlation with BMI, waist circumference, HOMA-IR, triglycerides, and a positive one with HDL-cholesterol and apoprotein AI. Multivariate regression analyses showed that cholesterol absorption markers predicted higher HDL-cholesterol levels, while HOMA-IR was a negative predictor of sitosterol and BMI a positive predictor of lathosterol. ConclusionsOur findings suggest the occurrence of an increased cholesterol synthesis in FCH, and an increased cholesterol absorption in pH. Markers of cholesterol synthesis cluster with clinical and laboratory markers of obesity and insulin resistance.

Exercise Enhances Whole-Body Cholesterol Turnover in Mice

Regular exercise reduces cardiovascular risk in humans by reducing cholesterol levels, but the underlying mechanisms have not been fully explored. Exercise might provoke changes in cholesterol and bile acid metabolism and thereby reduce cardiovascular risk. We examined whether voluntary wheel running in mice modulates cholesterol and bile acid metabolism. Male mice (10 wk old) were randomly assigned to have access to a voluntary running wheel for 2 wk (RUN group) or remained sedentary (SED group). Running wheel activity was recorded daily. In a first experiment, fecal sterol outputs, fecal bile acid profiles, plasma parameters, and expression levels of genes involved in cholesterol and bile acid metabolism were determined. In a second experiment, bile flow, biliary bile acid profile, and biliary secretion rates of cholesterol, phospholipids, and bile acids were determined. The RUN group ran an average of 10 km.d and displayed lower plasma cholesterol compared with SED (P = 0.030). Fecal bile acid loss was induced by approximately 30% in running mice compared with SED (P = 0.0012). A approximately 30% increase in fecal cholesterol output in RUN (P = 0.014) was consistent with changes in parameters of cholesterol absorption, such as reduced plasma plant sterol-cholesterol ratio (P = 0.044) and decreased jejunal expression of Npc1l1 (P = 0.013). Supportive of an increased cholesterol synthesis to compensate for fecal sterol loss were increased hepatic mRNA levels of HMGCoA reductase (P = 0.006) and an increased plasma lathosterol-cholesterol ratio (P = 0.0011) in RUN. Voluntary wheel running increased cholesterol turnover in healthy mice owing to an increased fecal bile acid excretion and a decreased intestinal cholesterol absorption. Enhanced cholesterol turnover may contribute to the established reduction of cardiovascular risk induced by regular exercise.

Effects of Oral Folate Supplementation on Serum Total Homocysteine and Cholesterol Levels in Hyperhomocysteinemic Children

Hyperhomocysteinemia may be a risk factor for cardiovascular disease even among children. Increased levels of total serum homocysteine (tHcy) may initiate atherosclerosis by modulating increased cholesterol synthesis in the liver. Folate supplementation has been found to reduce homocysteine levels. However, no data have been reported about the relationship between folate supplementation and cholesterol levels in children. Twenty of 26 hyperhomocysteinemic (>95th percentile for age) children underwent a therapeutic intervention of 5 mg of oral folate supplementation twice per week for 2 months. After the 2-month intervention with folate supplement, tHcy levels were statistically significantly decreased (P < .001), folate levels were significantly increased (P < .001), while total cholesterol levels were significantly improved from 183.8 (115-296 mg/dL) to 160.8 (109-265 mg/dL) (P < .05). Folate supplementation may reduce tHcy, serum folate, and total serum cholesterol levels in hyperhomocysteinemic children.

Obesity abrogates the concentration-dependent effect of leptin on endogenous cholesterol synthesis in human monocytes

Leptin the cytokine-like hormone is involved not only in local inflammations, but it regulates cholesterol biosynthesis in human monocytes. Since, monocyte-membrane composition in obesity shows considerable difference from control cells, our aim was to elucidate the concentration dependence of the effect of leptin in OW monocytes, and the downstream signaling of high and low leptin concentrations. Control and OW monocytes were stimulated with leptin in the presence or absence of different inhibitors. Our results are as follows: a concentration-dependent biphasic effect could only be detected in control monocytes whereas in OW cells only elevated cholesterol synthesis was found. The signal pathway of 50 ng/mL leptin stimulation involves Ca 2+ signal, activation of PI3K, MAPK and HMG CoA reductase. In the 500 ng/mL leptin-stimulated control monocytes the suppression of cholesterol synthesis was dependent on the Ca 2+ signal, the H-7 sensitive cPKC and PI3K activation, whereas in OW monocytes only PI3K was involved in increased cholesterol synthesis. We conclude that leptin-signaling in OW monocytes is characterized by Ca 2+ influx, abrogation of H-7 sensitive cPKC activation, and by PI3K mediated PKC activation.

HDL miR -ed Down by SREBP Introns

MicroRNAs that reduce cholesterol export from cells are encoded in the same genes that increase cholesterol synthesis.

Abstract 37: Alterations in the metabolism of highly motile cells: Implications for cancer metastasis

Abstract It has been known for some time that cancer cells have aberrant metabolism. Our lab observed that highly proliferative cells are not very motile, and likewise, highly motile cells do not proliferate rapidly. Thus, we hypothesized that cells direct their metabolism toward rapidly dividing or toward moving, but not both processes. This may be important in the progression of cancer from primary tumor to end-stage metastasis. By understanding how the metabolism and signaling pathways change in these very different situations, it may be possible to discover new drug targets to prevent cancers from progressing. Traditionally, studies of cellular metabolism and proliferation have been measured in fixed cells. In order to truly understand a living system, quantitative measurements in live cells are necessary. To this end, we utilized the Fluorescent Ubiquitination-based Cell Cycle Indicator or FUCCI, developed by Sakaue-Sawano et al. This system involves two vectors, one of which encodes Geminin fused to a green fluorescent probe, and the other which encodes Cdt1 fused to a red fluorescent probe. The levels of these proteins are regulated inversely during the cell cycle, with Geminin at its highest level during S, G2, and M phase, while Cdt1 is highest during G1. Therefore, when our stable transfectants are dividing (in S, G2, or M phases), their nuclei fluoresce green, while in the G1 phase of the cell cycle, their nuclei fluoresce red. Utilizing this system in our aggressive breast cancer cell lines enabled us to measure proliferation and metabolism in live cells. This also allowed us to directly test our hypothesis that actively motile cells are not proliferating (red), and proliferating cells (green) are not actively motile. By treating with different anti-proliferative and metabolic agents, we measured what percentage of cells cease dividing, and what percentage continued to grow. We used flow cytometry to separate these different populations and to determine genetic differences that may make them more or less resistant to these drugs. We also examined known genes involved in both metabolism and motility. To do this, we measured protein and mRNA expression of several proteins in the glycolysis, lipid metabolism, and cholesterol synthesis pathways, as well as the small motility-related GTPases. From our findings, a preliminary model of the interaction between metabolism and metastasis is emerging. The proteins likely involved in metastasis are small GTPases. These proteins are modified by prenylation, allowing them to localize to the cell membrane and direct motility. Our results suggest that MDA-MB-231 cells may have a slower rate of glycolysis, but display increased cholesterol synthesis to prenylate proteins, while SUM 149 cells have an increased rate of glycolysis. This may help explain the differences in the phenotypes of these cancers, and may allow for the prediction of future drug targets to prevent cancer metastasis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 37.

Insulin resistance is associated with increased cholesterol synthesis, decreased cholesterol absorption and enhanced lipid response to statin therapy

ObjectiveIncreasing insulin resistance is associated with a shift in cholesterol metabolism to increased synthesis and decreased absorption. Since statins inhibit cholesterol synthesis, we hypothesized that insulin-resistant patients will have greater LDL cholesterol (LDL-C) response to statins than insulin-sensitive patients. MethodsHigh-risk vascular patients not on lipid-lowering therapy were recruited and treated with Atorvastatin 80mg for 6 weeks. Percent LDL-C response to Atorvastatin was related to insulin sensitivity using the quantitative insulin sensitivity check index (QUICKI). Comparisons: (1) correlation between %LDL-C response and QUICKI. (2) Differences in cholesterol metabolism markers in insulin-resistant (lowest tertile QUICKI) vs insulin-sensitive patients (highest tertile of QUICKI). (3) Correlation of QUICKI with percent LDL-C response after correction for cholesterol metabolism markers. Results154 patients were enrolled of which 66 were suitable for this sub-study. Average LDL-C reduction was 57±12% (mean±SD). QUICKI correlated negatively with percent LDL-C reduction (Pearson's r=−0.258, p=0.037) and on regression analysis explained ∼7% (R2=0.067) of the variation in percent LDL-C response which approximates that reported by pharmacogenomics. Insulin-resistant patients had higher levels of cholesterol synthesis markers (desmosterol, lathosterol) and lower levels of absorption markers (cholestanol, sitosterol) and the correlation between QUICKI and percent LDL-C response ceased to be significant when these factors were controlled for. ConclusionsInsulin-resistant patients have superior LDL-C responses to statin therapy and that this may be related to increased cholesterol synthesis. BackgroundPatients with features of the metabolic syndrome, e.g. high triglycerides (TG) and low high density lipoprotein cholesterol (HDL-C) may have an enhanced benefit from statin therapy. A retrospective analysis from the 4S investigators where the study population was stratified by HDL-C and TG quartiles revealed variations in statin efficacy. Patients who fell into both the lowest quartile of HDL-C (<39mg/dl) and highest quartile of TG (>159mg/dl) had a greater frequency of features of the metabolic syndrome (high BMI, hypertension, diabetes) than the patients in the highest quartile of HDL-C (>52mg/dl) and lowest quartile of TG (<98mg/dl). The 4S investigators suggested that patients with low HDL-C and high TG achieved an enhanced clinical benefit from statins compared to patients with high HDL-C and low TG with hazard ratios of 0.48 and 0.86 respectively and a treatment-by-subgroup interaction p value of 0.03 [1]. Since the clinical benefit of statin therapy is directly proportional to achieved percent reduction in low density lipoprotein cholesterol (LDL-C) [2], we hypothesized that insulin-resistant patients would have greater percent decreases in LDL-C with statin therapy.

Plasma Non–cholesterol Sterols: A Useful Diagnostic Tool in Pediatric Hypercholesterolemia

Current guidelines strongly recommend the identification of genetic forms of hypercholesterolemia (HC) during childhood.The usefulness of non-cholesterol sterols (NCS) in the diagnosis of genetic HC has not been fully explored. Plasma NCS were measured by gas chromatography/mass spectrometry (GC/MS) in 113 children with hypercholesterolemia affected by: autosomal dominant hypercholesterolemia (ADH), familial combined hyperlipidemia(FCHL), polygenic hypercholesterolemia (PHC), and in 79 controls to evaluate: i) plasma NCS profile in different genetic HC and ii) the usefulness of NCS for the diagnosis of HC beyond current clinical criteria. ADH was characterized by raised lathosterol/total cholesterol (TC) and reduced phytosterols/TC ratios, indicative of increased cholesterol synthesis. FCHL showed a slight increase of lathosterol/TC ratio, whereas PHC showed increased phytosterols/TC ratios, indicative of increased cholesterol absorption. In a post hoc discriminant analysis of patients with HC, lipid values correctly classified the 73% (14 of 19) of ADH, whereas the inclusion of plasma sterols allowed the correct identification of all 19 patients with ADH. FCHL was not differentiated from PHC (62 versus 69%).In conclusion, NCS measurement showed that cholesterol plasma levels are related to the cholesterol synthesis in ADH and to cholesterol absorption in PHC. NCS improve the detection of ADH in pediatric patients, whereas FCHL diagnosis is not improved.

Berberine and plant stanols synergistically inhibit cholesterol absorption in hamsters

The present study was conducted to determine the efficacy and underlying mechanism of berberine (BBR), plant stanols (PS) and their combination on plasma lipids. Male Golden Syrian hamsters were randomly divided into 4 groups (n=15/group) and fed a cornstarch–casein–sucrose-based diet containing 0.15% cholesterol and 5% fat. Three treatment groups were supplemented with 0.17% (equivalent to 100mgkg−1d−1) BBR, 1% PS, or a combination of both (BBRPS) for 4wk. At the end of the study, plasma lipids were analyzed with enzymatic methods, cholesterol absorption and synthesis using stable isotope tracer methodology, and gene and protein expressions in the liver and small intestine using real-time PCR and Western blot, respectively. BBR and PS significantly lowered plasma total- and nonHDL-cholesterol levels, and BBRPS markedly improved cholesterol-lowering efficacy compared to BBR or PS alone. Further examinations revealed that BBR and PS both inhibited cholesterol absorption and by contrast, increased cholesterol synthesis, and exerted a synergistic action when they were combined. Plasma total or nonHDL-cholesterol levels were significantly correlated with cholesterol absorption rates. BBR upregulated sterol 27-hydroxlase gene expression and BBRPS increased both cholesterol-7α-hydroxylase and sterol 27-hydroxlase gene expressions. BBR and PS also synergistically decreased plasma triacylglycerides. These findings suggest that the cholesterol-lowering action of BBR might involve a combination of inhibition of cholesterol absorption and stimulation of bile acid synthesis. The combination of BBR and PS improves cholesterol-lowering efficacy through a synergistic action on cholesterol absorption, in addition to synergistically reducing plasma triacylglycerols in hamsters.

Absence of ApoE Upregulates Murine Brain ApoD and ABCA1 Levels, But Does Not Affect Brain Sterol Levels, While Human ApoE3 and Human ApoE4 Upregulate Brain Cholesterol Precursor Levels

Apolipoprotein E (apoE) is a regulator of peripheral cholesterol homeostasis, and the apoE-isoform E4 is a major risk factor for the development of Alzheimer's disease (AD). Accumulating evidence suggests a key role for aberrant cholesterol metabolism in AD. We hypothesized that apoE-deficiency in mice not only affects cholesterol homeostasis in the periphery, but also in the brain, and that this can be restored by astrocyte-specific expression of human apoE3, but not apoE4. Using gas-chromatography mass-spectrometry, we found that absence of apoE in mice does not affect brain cholesterol homeostasis although serum sterol levels increase dramatically, especially when the apoE-knockout mice are fed a high fat diet. We provide evidence suggesting that apoD and the ATP-binding Cassette Transporter A1 (ABCA1) play a compensatory role in the apoE-deficient brain. Surprisingly, astrocyte-specific expression of human apoE3 or apoE4 in brains of apoE-knockout mice significantly increases brain levels of cholesterol and its precursors compared to control mice, indicative of an increased cholesterol synthesis rate in the brain. This increase is independent of the apoE-isoform, suggesting that the detrimental effect of apoE4 on the pathogenesis of AD is unlikely to be due to an apoE-isoform effect on brain cholesterol homeostasis.