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Background and aims Infusion of high-density lipoprotein (HDL) mimetics failed to induce regression of atherosclerosis in recent randomized clinical trials. However, patients in these previous trials had normal levels of HDL-cholesterol, which potentially limited efficacy. Patients with very low levels of HDL-cholesterol and impaired cholesterol efflux capacity can be expected to derive the most potential benefit from infusion of HDL mimetics. This randomized clinical trial evaluated the efficacy of infusions of the HDL mimetic CER-001 in patients with genetically determined very low levels of HDL cholesterol. Methods In this multicenter, randomized clinical trial, we recruited patients with familial hypoalphalipoproteinemia (due to ABCA1 and/or APOA1 loss-of-function variants). Participants were randomized to intravenous infusions of 8 mg/kg CER-001 or placebo (2:1 ratio), comprising 9 weekly infusions followed by infusions every two weeks. Patients underwent repeated 3T-MRI to assess mean vessel wall area and 18F-FDG PET/CT to quantify arterial wall inflammation. Results A total of 30 patients with a mean age of 52.7 ± 7.4 years and HDL-cholesterol of 0.35 ± 0.25 mmol/L were recruited. After 24 weeks, the absolute change in mean vessel wall area was not significantly different in the CER-001 group compared with placebo (n = 27; treatment difference: 0.77 mm2, p = 0.21). Furthermore, there was no significant difference in carotid arterial wall inflammation (n = 24, treatment difference: 0.10 target-to-background ratio of the most diseased segment, p = 0.33) after 24 weeks. Conclusion In patients with genetically determined very low HDL-cholesterol, 24 weeks of treatment with HDL mimetic CER-001 did not reduce carotid vessel wall dimensions or arterial wall inflammation, compared with placebo.

Background High-density lipoprotein cholesterol (HDL-C) concentration is inversely related to risk of major adverse cardiovascular events (MACE) in epidemiologic studies but is a poorer predictor of MACE in patients with established coronary heart disease. HDL particle concentration (HDLP) has been proposed as a better predictor of risk. We investigated whether HDLP is associated with risk of MACE after acute coronary syndrome (ACS). Methods The dal-Outcomes trial compared the CETP inhibitor dalcetrapib with placebo in patients with recent ACS. In a nested case-cohort analysis, total, large, medium, and small HDLPs were measured by nuclear magnetic resonance spectroscopy at baseline (4-12 weeks after ACS) in 476 cases with MACE and 902 controls. Hazard ratios (HRs; case-control) for 1-SD increment of HDLP or HDL-C at baseline were calculated with and without adjustment for demographic, clinical, laboratory, and treatment variables. Similarly, HRs for MACE were calculated for changes in HDLP or HDL-C from baseline to month 3 of assigned treatment. Results Over median follow-up of 28 months, the risk of MACE was not associated with baseline HDLP (adjusted HR = 0.98, 95% CI = 0.84-1.15, P = .81), any HDLP subclass, or HDL-C. Dalcetrapib increased HDL-C and total, medium, and large HDLP and decreased small HDLP but had no effect on MACE compared with placebo. There were no association of risk of MACE with change in HDLP or HDL-C and no interaction with assigned study treatment. Conclusions Neither baseline HDLP nor the change in HDLP on treatment with dalcetrapib or placebo was associated with risk of MACE after ACS.

Ismail et al. show that 27-hydroxycholesterol, a peripheral cholesterol metabolite capable of passing the blood–brain barrier, reduces brain glucose uptake by upregulating the renin-angiotensin system and inhibiting GLUT4. This alteration affects memory processes and is likely to have implications on neurodegenerative diseases., Hypercholesterolemia is associated with cognitively deteriorated states. Here, we show that excess 27-hydroxycholesterol (27-OH), a cholesterol metabolite passing from the circulation into the brain, reduced in vivo brain glucose uptake, GLUT4 expression, and spatial memory. Furthermore, patients exhibiting higher 27-OH levels had reduced 18F-fluorodeoxyglucose uptake. This interplay between 27-OH and glucose uptake revealed the engagement of the insulin-regulated aminopeptidase (IRAP). 27-OH increased the levels and activity of IRAP, countered the IRAP antagonist angiotensin IV (AngIV)–mediated glucose uptake, and enhanced the levels of the AngIV-degrading enzyme aminopeptidase N (AP-N). These effects were mediated by liver X receptors. Our results reveal a molecular link between cholesterol, brain glucose, and the brain renin-angiotensin system, all of which are affected in some neurodegenerative diseases. Thus, reducing 27-OH levels or inhibiting AP-N maybe a useful strategy in the prevention of the altered glucose metabolism and memory decline in these disorders.

Epidemiological data associate higher concentrations of high-density lipoprotein cholesterol (HDL-C) with lower cardiovascular risk. HDL-C isolated from healthy subjects exhibits potentially protective properties, including anti-inflammatory effects [(1)][1]. However, some evidence suggests that

Little is known about whether cholesteryl ester transfer protein (CETP) genetic variation may modify the effect of weight-loss diets varying in fat content on changes in lipid levels. We analyzed the interaction between the CETP variant rs3764261 and dietary interventions on changes in lipid levels among 732 overweight/obese adults from a 2 year randomized weight-loss trial [Preventing Overweight Using Novel Dietary Strategies (POUNDS LOST)], and replicated the findings in 171 overweight/obese adults from an independent 2 year weight-loss trial [Dietary Intervention Randomized Controlled Trial (DIRECT)]. In the POUNDS LOST, participants with the CETP rs3764261 CC genotype on the high-fat diet had larger increases in HDL cholesterol (P = 0.001) and decreases in triglycerides (P = 0.007) than those on the low-fat diet at 6 months, while no significant difference between these two diets was observed among participants carrying other genotypes. The gene-diet interactions on changes in HDL-cholesterol and tri­glyc­erides were replicated in the DIRECT (pooled P for interaction ≤ 0.01). Similar results on trajectory of changes in HDL cholesterol and triglycerides over the 2 year intervention were observed in both trials. Our study provides replicable evidence that individuals with the CETP rs3764261 CC genotype might derive greater effects on raising HDL cholesterol and lowering triglycerides by choosing a low-carbohydrate/high-fat weight-loss diet instead of a low-fat diet.

BACKGROUND Familial hypercholesterolemia (FH) is an autosomal-dominant disorder caused by mutations in 1 of 3 genes. In the 60% of patients who are mutation negative, we have recently shown that the clinical phenotype can be associated with an accumulation of common small-effect LDL cholesterol (LDL-C)-raising alleles by use of a 12–single nucleotide polymorphism (12-SNP) score. The aims of the study were to improve the selection of SNPs and replicate the results in additional samples. METHODS We used ROC curves to determine the optimum number of LDL-C SNPs. For replication analysis, we genotyped patients with a clinical diagnosis of FH from 6 countries for 6 LDL-C-associated alleles. We compared the weighted SNP score among patients with no confirmed mutation (FH/M–), those with a mutation (FH/M+), and controls from a UK population sample (WHII). RESULTS Increasing the number of SNPs to 33 did not improve the ability of the score to discriminate between FH/M– and controls, whereas sequential removal of SNPs with smaller effects/lower frequency showed that a weighted score of 6 SNPs performed as well as the 12-SNP score. Metaanalysis of the weighted 6-SNP score, on the basis of polymorphisms in CELSR2 (cadherin, EGF LAG 7-pass G-type receptor 2), APOB (apolipoprotein B), ABCG5/8 [ATP-binding cassette, sub-family G (WHITE), member 5/8], LDLR (low density lipoprotein receptor), and APOE (apolipoprotein E) loci, in the independent FH/M– cohorts showed a consistently higher score in comparison to the WHII population (P < 2.2 × 10−16). Modeling in individuals with a 6-SNP score in the top three-fourths of the score distribution indicated a >95% likelihood of a polygenic explanation of their increased LDL-C. CONCLUSIONS A 6-SNP LDL-C score consistently distinguishes FH/M– patients from healthy individuals. The hypercholesterolemia in 88% of mutation-negative patients is likely to have a polygenic basis.

Background Aldosterone may have adverse effects in the myocardium and vasculature. Treatment with an aldosterone antagonist reduces cardiovascular risk in patients with acute myocardial infarction complicated by heart failure (HF) and left ventricular systolic dysfunction. However, most patients with acute coronary syndrome do not have advanced HF. Among such patients, it is unknown whether aldosterone predicts cardiovascular risk. Methods and Results To address this question, we examined data from the dal‐OUTCOMES trial that compared the cholesteryl ester transfer protein inhibitor dalcetrapib with placebo, beginning 4 to 12 weeks after an index acute coronary syndrome. Patients with New York Heart Association class II (with LVEF III , or IV HF were excluded. Aldosterone was measured at randomization in 4073 patients. The primary outcome was a composite of coronary heart disease death, nonfatal myocardial infarction, stroke, hospitalization for unstable angina, or resuscitated cardiac arrest. Hospitalization for HF was a secondary endpoint. Over a median follow‐up of 37 months, the primary outcome occurred in 366 patients (9.0%), and hospitalization for HF occurred in 72 patients (1.8%). There was no association between aldosterone and either the time to first occurrence of a primary outcome (hazard ratio for doubling of aldosterone 0.92, 95% confidence interval 0.78‐1.09, P =0.34) or hospitalization for HF (hazard ratio 1.38, 95% CI 0.96‐1.99, P =0.08) in Cox regression models adjusted for covariates. Conclusions In patients with recent acute coronary syndrome but without advanced HF, aldosterone does not predict major cardiovascular events. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 00658515.

The two oxysterols, 27-hydroxycholesterol (27OH) and 24S-hydroxycholesterol (24OH), are both inhibitors of cholesterol synthesis and activators of the liver X receptor (LXR) in vitro. Their role as physiological regulators under in vivo conditions is controversial, however. In the present work, we utilized a previously described mouse model with overexpressed human sterol 27-hydroxylase (CYP27A1). The levels of 27OH were increased about 12-fold in the brain. The brain levels of HMG-CoA reductase mRNA and HMG-CoA synthase mRNA levels were increased. In accordance with increased cholesterol synthesis, most of the cholesterol precursors were also increased. The level of 24OH, the dominating oxysterol in the brain, was decreased by about 25%, most probably due to increased metabolism by CYP27A1. The LXR target genes were unaffected or slightly changed in a direction opposite to that expected for LXR activation. In the brain of Cyp27−/− mice, cholesterol synthesis was slightly increased, with increased levels of cholesterol precursors but normal mRNA levels of HMG-CoA reductase and HMG-CoA synthase. The mRNA levels corresponding to LXR target genes were not affected. The results are consistent with the possibility that both 24OH and 27OH are physiological suppressors of cholesterol synthesis in the brain. The results do not support the contention that 27OH is a general activator of LXR target genes in this organ.

Background & Aims Non-alcoholic steatohepatitis is characterized by hepatic steatosis with inflammation. Although steatosis is benign and reversible, inflammation can increase liver damage. Hepatic inflammation has been associated with accumulation of cholesterol in lysosomes of Kupffer cells. 27-Hydroxycholesterol (27HC), a derivative of cholesterol formed by CYP27A1, can mobilize cholesterol from the lysosomes to the cytoplasm. We investigated whether 27HC can change the intracellular distribution cholesterol and reduce hepatic inflammation in mice. Methods We transplanted bone marrow from irradiated wild-type or Cyp27a1 −/− mice to mice that do not express the low density lipoprotein receptor ( Ldlr −/− ), which are hyperlipidemic; 9 weeks later, mice were fed either regular chow or a high-fat, high-cholesterol (HFC) diet for 3 months. In a separate experiment, Ldlr −/− mice were given subcutaneous injections of 27HC and placed on regular chow or HFC diets for 3 weeks. Blood and liver tissues samples were collected and analyzed for intracellular cholesterol distribution and inflammation. Results In Ldlr −/− mice that received bone marrow transplants from Cyp27a1 −/− mice, lysosomes of Kupfer cells had a greater accumulation of cholesterol than those of mice that received bone marrow from wild-type mice, after the HFC diet. Liver histology and gene expression analyses showed increased inflammation and liver damage in mice given bone marrow transplants from Cyp27a1 −/− mice and placed on the HFC diet. Administration of 27HC to Ldlr −/− mice, following the HFC diet, reduced the accumulation of lysosomal cholesterol and hepatic inflammation, compared with mice that were not given 27HC. Conclusions Accumulation of cholesterol in lysosomes of Kupfer cells promotes hepatic inflammation in mice. The cholesterol derivative 27HC reduces accumulation of cholesterol in lysosomes and might be used to treat non-alcoholic steatohepatitis.

Drugs to raise HDL cholesterol (HDL-C) have generally failed to decrease major adverse cardiovascular events (MACE). HDL particle concentration (HDLP) has been proposed as a better predictor of MACE than HDL-C. We determined whether HDLP is associated with risk of MACE after acute coronary syndrome

Macrophage scavenger receptor 1 (MSR1) mediates the uptake of modified low density lipoprotein (LDL)-cholesterol. The significance of MSR1 in atherosclerosis development in animal models is uncertain. In this study we sought to determine the significance of MSR1 polymorphisms in its encoding gene in susceptibility to atherosclerosis.We genotyped three polymorphic sites in the MSR1 gene including a 3-bp "TTA" insertion-deletion in intron 7 (rs3036811, Indel 7), an intron 5 SNP (rs33959637, IVS5-59), and a missense coding single nucleotide polymorphism (SNP) in exon 6 (rs3747531, P275A) in 136 nondiabetic Ashkenazi men under age 55 years (mean = 47.3 +/- 4.8 years) undergoing coronary angiography. Assessment of coronary disease was done by the number of segments with stenosis greater than 20% (coronary artery narrowing greater than 20% [CAGE20%]), greater than 50% (CAGE50%), and total number of diseased vessels. Linear regression modeling was used to define associations between atherosclerotic burden and MSR1 SNPs and haplotypes.Significant associations were noted between IVS5-59 and number of diseased vessels (p = 0.009) and CAGE20% (p = 0.017), which remained significant upon controlling for age, cholesterol level, hypertension, and smoking.This study demonstrates an association between MSR1 polymorphisms and atherosclerosis, suggesting that atherosclerotic risk associated with classic risk factors may be modified by MSR1 polymorphisms. These findings point to a significant role of MSR1 in atherosclerosis.

27-Hydroxycholesterol (27OH) is a strong suppressor of cholesterol synthesis and a weak activator of LXR in vitro. The regulatory importance of 27OH in vivo is controversial. Here we utilized male mice with increased levels of 27OH either due to increased production (CYP27A1 transgenic mice) or reduced metabolism (Cyp7b1-/- mice). We also used mice lacking 27OH due to a knockout of Cyp27a1. The latter mice were treated with cholic acid to compensate for reduced bile acid synthesis. The effects of the different levels of 27OH on Srebp- and other LXR-regulated genes in the liver were investigated. In the liver of CYP27tg mice we found a modest increase of the mRNA levels corresponding to the LXR target genes Cyp7b1 and Abca1. A number of other LXR-regulated genes were not affected. The effect on Abca1 mRNA was not seen in the liver of Cyp7b1-/- mice. There were little or no effects on cholesterol synthesis. In the liver of the Cyp27-/- mice treated with 0.025% cholic acid there was no significant effect of the knockout on the LXR target genes. In a previous work triple-knockout mice deficient in the biosynthesis of 24S-hydroxycholesterol, 25-hydroxycholesterol and 27OH were shown to have impaired response to dietary cholesterol, suggesting side-chain oxidized oxysterols to be mediators in cholesterol-induced effects on LXR target genes at a transcriptional level (Chen W. et al., Cell Metab. 5 (2007) 73-79). The hydroxylated oxysterol responsible for the effect was not defined. We show here that treatment of wildtype mice with dietary cholesterol under the same conditions as in the above study induced the LXR target genes Lpl, Abcg8 and Srebp1c in wild type mice but failed to activate the same genes in mice lacking 27-hydroxycholesterol due to a knockout of Cyp27. We failed to demonstrate the above effects at the protein level (Abcg8) or at the activity level (Lpl). The results suggest that 27OH is not an important regulator of Srebp- or LXR regulated genes under basal conditions in mouse liver. On the other hand 27OH appears to mediate cholesterol-induced effects on some LXR target genes at a transcriptional level under some in vivo conditions.

Background: Genetic variation in the alcohol dehydrogenase (ADH) enzyme is associated with an aversion to alcohol and a lower risk of alcoholism among Asians. There is growing evidence of a functional role of the ADH2*2 allele in alcohol-drinking patterns among Jews, who have traditionally exhibited low rates of alcoholism and alcohol-related problems. The mechanism by which this allelic effect is mediated is not yet clearly understood. This study examined the effect of ADH2*2 on alcohol-elimination rates (AER) under experimental conditions. Methods: Young adult male Jews (N= 109) received an intravenous alcohol infusion; metabolism was measured by using standard breath alcohol concentration tests. A clamping technique was used to achieve and maintain a target breath alcohol concentration of 50 mg/100 ml for a defined time period. The AER at steady state was calculated. The alcohol disappearance rate was also calculated from the descending limb slope. Polymerase chain reaction was used for allelic determination of the ADH2 and ADH3 loci. Results: The mean AER among ADH2*2 carriers was significantly higher (8.09 ± 1.4 g/hr) than among ADH2*1 homozygotes (7.14 ± 1.5 g/hr; p= 0.003). Significance was retained on adjustment for potential confounding covariates. The ADH2 allele explains 8.5% of the AER variance in this population. Little AER difference was observed across ADH3 genotype groups. The slope of the descending limb increased with increasing copies of the ADH2*2 allele. Conclusions: The rate of alcohol elimination is significantly associated with the ADH2 genotype of Jewish males. Evidence for variation in alcohol metabolism across ADH genotypic groups provides support for the role of physiologic protective factors in alcohol drinking and suggests that reduced drinking among Jews may be genetically as well as environmentally determined. We believe that application of the novel “Indiana clamp” enhances AER measurement accuracy, allowing for detection of hitherto undetectable differences.

Sterol 27-hydroxylase (CYP27A1) is required for bile acid synthesis by both the classical and alternate pathways. Cyp27a1 −/− mice exhibit a dramatic increase in the activity of cytochrome P450 3A (CYP3A), which catalyzes side-chain hydroxylations of bile acid intermediates, thereby facilitating their excretion in the bile and urine. We examine the role of the nuclear xenobiotic receptor PXR (pregnane X receptor) in this process. We demonstrate that expression of Cyp3a11 and other established PXR target genes is increased in the Cyp27a1 −/− mice. When Cyp27a1 −/− mice are fed a diet containing either cholic acid or chenodeoxycholic acid, expression of CYP7A1, which catalyzes the rate-limiting step in bile acid biosynthesis, is strongly suppressed. In parallel, the induction of Cyp3a11 observed in these mice is reversed, suggesting that bile acid intermediates serve as PXR activators. In support of this hypothesis, three potentially toxic sterols (7α-hydroxy-4-cholesten-3-one, 5β-cholestan-3α,7α,12α-triol, and 4-cholesten-3-one), including two that are known to accumulate in Cyp27a1 −/− mice, are efficacious activators of mouse PXR. All three compounds are more potent activators of mouse PXR than of human PXR, which may explain in part why humans who lack functional CYP27A1 do not display a corresponding increase in CYP3A activity and are stricken with the disease cerebrotendinous xanthomatosis. Taken together, these results reveal the existence of a feedforward regulatory loop by which potentially toxic bile acid intermediates activate PXR and induce their own metabolism. In addition, this study demonstrates that animal models with alterations in gene expression can be used to identify endogenous ligands for orphan nuclear receptors.

Sterol-regulatory element-binding protein (SREBP)-2 is a key regulator of cholesterol. When cells are deprived of cholesterol, proteolytic cleavage releases the NH 2 -terminal domain of SREBP-2 that binds and activates the promoters of SREBP-2-regulated genes including the genes encoding the low-density lipoprotein (LDL) receptor, 3-hydroxymethyl-3-glutaryl-(HMG-)CoA-synthase, and HMG-CoA-reductase. Thus, SREPB-2 gene activation leads to enhanced cholesterol uptake and biosynthesis. A novel protein polymorphism (SREBP-2-595A/G) discovered in the regulatory domain of human SREBP-2 was investigated regarding its impact on cholesterol homeostasis. In human embryonic kidney (HEK)-293-cells, the cleavage-rate of the SREBP-2-595A-isoform was slightly decreased compared to that of the SREBP-2-595G-isoform. Since cleavage of SREBP-2 activates the LDL receptor-mediated uptake of plasma cholesterol, we hypothesized the LDL receptor-mediated uptake to be decreased in homozygous SREBP-2-595A-carriers and thus, plasma total cholesterol (TC) to be higher than in SREBP-2-595G-carriers. Multiple linear regression analysis of population samples from Switzerland ( N =1334) and Israel ( N =923) demonstrated a significant positive, gene dose-dependent association of the SREBP-2-595A-isoform with higher plasma TC ( P =0.001). This cholesterol-modulating effect was present in hypercholesterolaemic (ΔTC=1.05 mmol/l, 14.4%; P =0.002; N =477), but absent in normocholesterolaemic subjects (ΔTC=0.06 mmol/l, 1.4%; P =0.334; N =1780). In summary, a slightly but constantly decreased cleavage-rate of the SREBP-2-595A-isoform compared to that of the SREBP-2-595G-isoform may lead to a reduced transcriptional activation of the LDL receptor-gene weakening the SREBP-mediated compensation mechanisms, and may, therefore, be a critical factor in the development of polygenic hypercholesterolaemia.

The accumulation of various 25-hydroxylated C(27)-bile alcohols in blood and their excretion in urine are characteristic features of cerebrotendinous xanthomatosis (CTX) a recessively inherited inborn error of bile acid synthesis caused by mutations in the mitochondrial sterol 27-hydroxylase (CYP27) gene. These bile alcohols may be intermediates in the alternative cholic acid side chain cleavage pathway. The present study was undertaken to identify enzymes and reactions responsible for the formation of these bile alcohols and to explain why Cyp27(-/-) mice do not show CTX-related abnormalities. Microsomal activities of 5beta-cholestane-3alpha,7alpha,12alpha-triol 25- and 26-hydroxylases, 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol 23R-, 24S-, and 27-hydroxylases and testosterone 6beta-hydroxylase, a marker enzyme for CYP3A, in Cyp27(-/-) mice livers were markedly up-regulated (5.5-, 3.5-, 6.5-, 7.5-, 2.9-, and 5.4-fold, respectively). In contrast, these enzyme activities were not increased in CTX. The activities of 5beta-cholestane-3alpha,7alpha,12alpha-triol 25- and 26-hydroxylases and 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol 23R-, 24R-, 24S-, and 27-hydroxylases were strongly correlated with the activities of testosterone 6beta-hydroxylase in control human liver microsomes from eight unrelated donors. Troleandomycin, a specific inhibitor of CYP3A, markedly suppressed these microsomal side chain hydroxylations in both mouse and human livers in a dose-dependent manner. In addition, experiments using recombinant overexpressed human CYP3A4 confirmed that these microsomal side chain hydroxylations were catalyzed by a single enzyme, CYP3A4. The results demonstrate that microsomal 25- and 26-hydroxylations of 5beta-cholestane-3alpha,7alpha,12alpha-triol and microsomal 23R-, 24R-, 24S-, and 27-hydroxylations of 5beta-cholestane-3alpha,7alpha,12alpha,25-tetrol are mainly catalyzed by CYP3A in both mice and humans. Unlike Cyp27(-/-) mice, CYP3A activity was not up-regulated despite marked accumulation of 5beta-cholestane-3alpha,7alpha,12alpha-triol in CTX.

Cerebrotendinous xanthomatosis (CTX) is a rare autosomal recessive sterol storage disease characterised clinically by juvenile bilateral cataracts, progressive neurological dysfunction, and formation of tendon xanthomata. We describe the clinical and biochemical features, molecular diagnosis and long-term management of the first reported Australasian case of CTX. Molecular analysis confirmed the diagnosis of CTX and demonstrated that the patient was homozygous for a G→A transition in the splice donor site of intron 4 of the sterol 27-hydroxylase gene. Serum cholestanol concentrations were decreased with the HMG-CoA reductase inhibitor simvastatin alone and greater reductions were achieved after the addition of the bile acid chenodeoxycholic acid; suggesting a synergistic effect of this combination. Despite serum cholestanol concentrations remaining within the low-normal range, there has been no significant improvement in mental and physical abilities or in EEG abnormalities with 5 years of treatment. Metabolism of radiolabeled 7-ketocholesterol to aqueous soluble products was absent in CTX-derived macrophages. Consistent with this finding, plasma 7α-hydroxycholesterol, 7β-hydroxycholesterol, and 7-ketocholesterol concentrations were increased in the CTX subject compared with controls.

Cerebrotendinous xanthomatosis (CTX) is a rare, recessively inherited lipid storage disease characterized by a markedly reduced production of chenodeoxycholic acid and an increased formation of 25-hydroxylated bile alco- hols and cholestanol. Patients with this disease are known to have mutations in the sterol 27-hydroxylase ( Cyp27 ) gene. However, one study showed that mice with a disrupted Cyp27 gene did not have any CTX-related clinical or bio- chemical abnormalities. To explore the reason, hepatic cho- lesterol, cholestanol, and 12 intermediates in bile acid bio- synthetic pathways were quantified in 10 Cyp27 � / � and 7 Cyp27 � / � mice, two CTX patients (untreated and treated with chenodeoxycholic acid), and four human control sub- jects by high resolution gas chromatography-mass spectrom- etry. Mitochondrial 27-hydroxycholesterol and 5 � -choles- tane-3 � ,7 � ,12 � ,27-tetrol were virtually absent in both Cyp27 � / � mice and CTX patients. In Cyp27 � / � mice, mi- crosomal concentrations of intermediates in the early bile acid biosynthetic pathway (7 � -hydroxycholesterol, 7 � - hydroxy-4-cholesten-3-one, 7 � ,12 � -dihydroxy-4-cholesten-3- one, and 5 � -cholestane-3 � ,7 � ,12 � -triol), 25-hydroxylated bile alcohols (5 � -cholestane-3 � ,7 � ,12 � ,25-tetrol, 5 � -cholestane- 3 � ,7 � ,12 � ,23 R ,25-pentol, and 5 � -cholestane-3 � ,7 � ,12 � ,24 R , 25-pentol), and cholestanol were all significantly elevated compared with those in Cyp27 � / � mice, although the levels were lower than those in untreated CTX patients. The inter- mediate levels in early bile acid biosynthesis were more ele- vated in male (16-86% of CTX) than in female Cyp27 � / � mice (7-30% of CTX). In contrast, 25-hydroxylated bile alco- hol concentrations were not significantly different between male and female Cyp27 � / � mice and were considerably lower (less than 14%) than those in CTX patients. These results suggest that 1 ) in Cyp27 � / � mice, especially in fe- males, classic bile acid biosynthesis via 7 � -hydroxycholesterol is not stimulated as much as in CTX patients; and 2 ) formed 25-hydroxylated bile alcohols are more efficiently metabo- lized in Cyp27 � / � mice than in CTX patients. —Honda, A., G. Salen, Y. Matsuzaki, A. K. Batta, G. Xu, E. Leitersdorf, G. S. Tint, S. K. Erickson, N. Tanaka, and S. Shefer. Differences in hepatic levels of intermediates in bile acid biosynthesis between Cyp27 � / � mice and CTX. J. Lipid Res. 2001. 42: 291-300.

Sterol 27-hydroxylase (CYP27) participates in the conversion of cholesterol to bile acids. We examined lipid metabolism in mice lacking the Cyp27 gene. On normal rodent chow,Cyp27 −/− mice have 40% larger livers, 45% larger adrenals, 2-fold higher hepatic and plasma triacylglycerol concentrations, a 70% higher rate of hepatic fatty acid synthesis, and a 70% increase in the ratio of oleic to stearic acid in the liverversus Cyp27 +/+ controls. InCyp27 −/− mice, cholesterol 7α-hydroxylase activity is increased 5-fold, but bile acid synthesis and pool size are 47 and 27%, respectively, of those in Cyp27 +/+mice. Intestinal cholesterol absorption decreases from 54 to 4% in knockout mice, while fecal neutral sterol excretion increases 2.5-fold. A compensatory 2.5-fold increase in whole body cholesterol synthesis occurs in Cyp27 −/− mice, principally in liver, adrenal, small intestine, lung, and spleen. The mRNA for the cholesterogenic transcription factor sterol regulatory element-binding protein-2 (SREBP-2) and mRNAs for SREBP-2-regulated cholesterol biosynthetic genes are elevated in livers of mutant mice. In addition, the mRNAs encoding the lipogenic transcription factor SREBP-1 and SREBP-1-regulated monounsaturated fatty acid biosynthetic enzymes are also increased. Hepatic synthesis of fatty acids and accumulation of triacylglycerols increases in Cyp27 −/− mice and is associated with hypertriglyceridemia. Cholic acid feeding reverses hepatomegaly and hypertriglyceridemia but not adrenomegaly inCyp27 −/− mice. These studies confirm the importance of CYP27 in bile acid synthesis and they reveal an unexpected function of the enzyme in triacylglycerol metabolism.

Mean high-density lipoprotein cholesterol (HDL-C) concentrations are low in the Jewish population of Israel. With this in mind we assessed the association of the Taq1B CETP polymorphism, plasma CETP mass and plasma lipid, lipoprotein and apolipoprotein concentrations in a sample of 884 Jerusalem residents aged 28-32. The allele frequency (0.435 +/- 0.017(S.E.)) is similar to that reported elsewhere. There was a strong (apparently codominant) association of the Taq1 B allele with plasma CETP in both sexes, and an inverse association with HDL-C and apo A-1, significant in women and undiminished upon adjustment for plasma CETP. There was evidence in this population for an admixture of two plasma CETP distributions, with 9% belonging to a distribution with the higher mean, pointing to a possible major gene effect. Mean plasma CETP was higher in women than men. Plasma CETP was inversely associated with HDL-C in men but not in women (P0.05 for the sex difference, multivariate analysis), inversely related to the HDL-C/apo A-1 ratio in men and positively related in women (P0.005 for the sex difference), and was positively associated with total cholesterol (TC) and low-density lipoprotein cholesterol in both sexes, and with the TC/HDL-C ratio and apo B in men alone. The sex differences may reflect dissimilarities in the regulatory function of CETP in lipid exchange. The absence of an unusual allele frequency of the Taq1B CETP polymorphism and its relatively modest association with HDL-C argue against an important role for this or strongly linked sites in determining the low population levels of HDL-C in Israel.

The peroxisome proliferator-activated receptor alpha (PPARalpha) plays a key role in lipid and lipoprotein metabolism. However, important inter- and intraspecies differences exist in the response to PPARalpha activators. This incited us to screen for PPARalpha variants with different signaling functions. In the present study, using a RT-PCR approach a variant human PPARalpha mRNA species was identified, which lacks the entire exon 6 due to alternative splicing. This deletion leads to the introduction of a premature stop codon, resulting in the formation of a truncated PPARalpha protein (PPARalphatr) lacking part of the hinge region and the entire ligand-binding domain. RNase protection analysis demonstrated that PPARalphatr mRNA is expressed in several human tissues and cells, representing between 20-50% of total PPARalpha mRNA. By contrast, PPARalphatr mRNA could not be detected in rodent tissues. Western blot analysis using PPARalpha-specific antibodies demonstrated the presence of an immunoreactive protein migrating at the size of in vitro produced PPARalphatr protein both in human hepatoma HepG2 cells and in human hepatocytes. Both in the presence or absence of 9-cis-retinoic acid receptor, PPARalphatr did not bind to DNA in gel shift assays. Immunocytochemical analysis of transfected CV-1 cells indicated that, whereas transfected PPARalphawt was mainly nuclear localized, the majority of PPARalphatr resided in the cytoplasm, with presence in the nucleus depending on cell culture conditions. Whereas a chimeric PPARalphatr protein containing a nuclear localization signal cloned at its N-terminal localized into the nucleus and exhibited strong negative activity on PPARalphawt transactivation function, PPARalphatr interfered with PPARalphatr transactivation function only under culture conditions inducing its nuclear localization. Cotransfection of the coactivator CREB-binding protein relieved the transcriptional repression of PPARalphawt by PPARalphatr, suggesting that the dominant negative effect of PPARalphatr might occur through competition for essential coactivators. In addition, PPARalphatr interfered with transcriptional activity of other nuclear receptors such as PPARgamma, hepatic nuclear factor-4, and glucocorticoid receptor-alpha, which share CREB-binding protein/p300 as a coactivator. Thus, we have identified a human PPARalpha splice variant that may negatively interfere with PPARalphawt function. Factors regulating either the ratio of PPARalphawt vs. PPARalphatr mRNA or the nuclear entry of PPARalphatr protein should therefore lead to altered signaling via the PPARalpha and, possibly also, other nuclear receptor pathways.

Sterol 27-hydroxylase is important for the degradation of the steroid side chain in conversion of cholesterol into bile acids and has been ascribed a regulatory role in cholesterol homeostasis. Its deficiency causes the autosomal recessive disease cerebrotendinous xanthomatosis (CTX), characterized by progressive dementia, xanthomatosis, and accelerated atherosclerosis. Mice with a disrupted cyp27 (cyp27(-/-)) had normal plasma levels of cholesterol, retinol, tocopherol, and 1,25-dihydroxyvitamin D. Excretion of fecal bile acids was decreased (

The hypolipidemic action of fibrates has recently been shown to involve the activation of peroxisome proliferator activated receptors establishing a molecular mechanism for this class of drugs. Increasing clinical trial evidence supports the efficacy of fibrates in the treatment of dyslipoproteinemias, particularly in patients with hypertriglyceridemia and low high-density lipoproteins.

Cultured macrophages and endothelial cells have been reported to secrete 27-oxygenated metabolites of cholesterol. This mechanism was compared with the classical high density lipoprotein (HDL)-dependent reverse cholesterol transport. Under standard conditions, macrophage preparations had considerably higher capacity to secrete 27-hydroxycholesterol and 3β-hydroxy-5-cholestenoic acid than had endothelial cells and fibroblasts. Western blotting showed that lung macrophages contained the most sterol 27-hydroxylase protein of the cells tested. The relative amounts of 3β-hydroxy-5-cholestenoic acid produced by the macrophages were also highest. Macrophages derived from monocytes of patients with sterol 27-hydroxylase deficiency did not secrete 27-oxygenated products, demonstrating that sterol 27-hydroxylase is the critical enzyme for the conversion of cholesterol into the 27-oxygenated steroids. That sterol 27-hydroxylase is responsible not only for 27-hydroxylation of cholesterol but also for the further oxidation of this steroid into 3β-hydroxy-5-cholestenoic acid was shown with use of tritium-labeled 27-hydroxycholesterol and an inhibitor of sterol 27-hydroxylase. Secretion of 27-oxygenated products by the cultured macrophages as well as the ratio between the alcohol and the acid appeared to be dependent upon total 27-hydroxylase activity, the availability of substrate cholesterol, and the presence of an acceptor for 27-hydroxycholesterol in the medium. With albumin as extracellular acceptor, the major secreted product was 3β-hydroxy-5-cholestenoic acid. Under such conditions, secretion of labeled 27-oxygenated products was higher than that of labeled cholesterol from lung alveolar macrophages preloaded with [4-14C]cholesterol. With HDL as acceptor, 27-hydroxycholesterol was the major secreted product, and the total secretion of labeled 27-oxygenated products was only about 10% of that of labeled cholesterol. Thus, 27-hydroxycholesterol and cholesterol may compete for HDL-mediated efflux from the cells. The results support the contention that the sterol 27-hydroxylase-mediated elimination of cholesterol is more important in macrophages than in endothelial cells. This mechanism may be an alternative and/or a complement to the classical HDL-mediated reverse cholesterol transport in macrophages, in particular when the concentration of HDL is low.

Familial hypercholesterolemia (FH) is a monogenic disorder caused by mutations in the low-density lipoprotein (LDL) receptor gene. Large variations in plasma lipids and lipoprotein levels have been observed in FH families. These may be caused by other environmental and genetic factors of which apolipoprotein E (apo E) is a candidate. The possible influence of apo E polymorphism on components of variation in plasma LDL-C, triglycerides, high-density lipoprotein cholesterol (HDL-C), and lipoprotein(a) (Lp(a)) levels was investigated in 235 members of 14 families with FH. Sex-and age-adjusted mean LDL-C was influenced significantly by the apo E genotype in non-FH subjects (P

This study assessed the long-term use of fluvastatin, alone or in combination with bezafibrate, in patients with severe familial hypercholesterolemia who, in a previous study, did not achieve target levels (European Atherosclerosis Society) of low density lipoprotein cholesterol (LDL-C) with fluvastatin at 60 mg/day plus bezafibrate 200 mg/day, with or without cholestyramine (CME) at 8 g/day. This open-label study comprised 3 periods: period I, 6 weeks of fluvastatin at 40 mg twice daily (at breakfast and at bedtime); period II, fluvastatin at 80 mg/day (40 mg at breakfast, 40 mg at bedtime), and bezafibrate at 200 mg/day (at lunchtime) for 6 weeks in patients not achieving LDL-C target levels; and period III, force-titration of fluvastatin to 800 mg/day (as in period II) and bezafibrate at 400 mg/day (slow release) in patients receiving combination treatment. Patients were excluded if, during the previous study, they had experienced a serious drug-related adverse event or deterioration in liver or kidney function (liver enzymes > 3 times upper limit of normal). The standard physical and laboratory evaluations were performed at regular intervals. Lipid profiles were determined from 12-hour fasting blood samples. All adverse events occurring or worsening during the study, whether spontaneously reported or elicited by questioning, and regardless of relationship to study medication, were recorded.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of genetic and environmental factors in determining the variability in plasma lipoprotein(a) [Lp(a)] levels was investigated in 220 members of 14 families with familial hypercholesterolemia (FH) whose plasma Lp(a) levels were previously reported [Leitersdorf et al. (1991) J Lipid Res 32:1513-1519]. One hundred four subjects harbored a mutant low density lipoprotein (LDL) receptor allele as confirmed by the identification of the specific mutations in addition to the haplotype analysis reported before. Four different mutant alleles were identified, each in a defined genetic group--Druze, Christian-Arabs, Ashkenazi, and Sepharidic Jews. Sex- and age-adjusted mean plasma Lp(a) levels were significantly higher in FH family members (34.0 mg/dl) than in non-FH family members (21.1 mg/dl). Lp(a) levels were further adjusted for lipid levels and apo(a) isoforms. A mixture of two normal distributions fitted the adjusted Lp(a) levels better than did a single normal distribution. Segregation analysis indicated that a major effect of a non-transmitted environmental factor explained the mixture of distributions in addition to polygenic loci which influenced Lp(a) levels within each distribution. The major environmental factor and the polygenic loci accounted for 45% and 20% of the adjusted Lp(a) variation, respectively. Furthermore, sex, age, lipid levels, apo(a) isoform, the major environmental effect, and the unmeasured polygenes could account for 80% of the unadjusted variation of plasma Lp(a) in these families.

Hydroxymethylglutaryl coenzyme A (HMG CoA) reductase inhibitors are potent cholesterol reducing agents that have been successfully used for the treatment of heterozygous familial hypercholesterolaemia (FH). A recent investigation revealed that several constitutional and genetic factors significantly determined the response of plasma lipids and lipoproteins to the HMG CoA reductase inhibitor fluvastatin. Gender has been identified through multivariate analysis as a major determinant of the plasma high density lipoprotein (HDL) cholesterol response. The current analysis was undertaken to determine possible gender-related fluvastatin dose-response differences. The analysis revealed that for HDL cholesterol, gender-related differences reach statistical significance only at the highest fluvastatin dose of 40 mg/day (females 22.9%, males 12.9%, p0.01). In parallel, the change in low density lipoprotein (LDL) cholesterol: HDL cholesterol ratio, an indicator of ischaemic heart disease risk, was also found to be affected by gender (females -38.4%, males -32.2%, p0.01). For LDL cholesterol, no consistent gender-related differences were found. In conclusion, the response of plasma lipid levels to fluvastatin in heterozygote FH patients is significantly affected by gender, with females achieving a more marked overall response, as indicated by higher HDL cholesterol levels and a lower LDL cholesterol: HDL cholesterol ratio.

The efficacy and safety of the HMG CoA reductase inhibitor fluvastatin have been evaluated in a double blind study in 52 patients with familial hypercholesterolaemia. A standard AHA Phase II lipid lowering diet was prescribed throughout the study. After 6 weeks of a single blind dosage stabilisation period, in which patients received fluvastatin 40 mg qPM, patients were randomly allocated to one of two double blind treatment groups: group A (n = 24) received fluvastatin 20 mg b.d. for 12 weeks and fluvastatin 20 mg AM + 40 mg PM for an additional 12 weeks; Group B (n = 28) received fluvastatin 40 mg qPM during the entire study. Safety and tolerability were evaluated by the analysis of biochemical and haematological parameters, and ophthalmological and physical examinations. Efficacy was analysed by the determination of plasma lipids, lipoproteins and apoproteins. Fluvastatin 40 mg/d was associated with up to a 27.4% decrease in LDL-C and a 9.6% increase in HDL-C concentrations. Increasing the dose of fluvastatin from 20 mg b.d. to 60 mg per day in Group A was associated with a 7.1% decrease in LDL-C, a 12.1% increase of HDL-C and a 12.8% decrease in the LDL-C/HDL-C ratio. In comparison with Group B (40 mg qPM) LDL-C, HDL-C and the LDL-C/HDL-C ratio in Group A (60 mg) differed by -8.9%, 6.6% and -12%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The rare disease cerebrotendinous xanthomatosis (CTX) is due to a lack of sterol 27-hydroxylase (CYP27A1) and is characterized by cholestanol-containing xanthomas in brain and tendons. Mice with the same defect do not develop xanthomas. The driving force in the development of the xanthomas is likely to be conversion of a bile acid precursor into cholestanol. The mechanism behind the xanthomas in the brain has not been clarified. We demonstrate here that female cyp27a1(-/-) mice have an increase of cholestanol of about 2.5- fold in plasma, 6-fold in tendons, and 12-fold in brain. Treatment of cyp27a1(-/-) mice with 0.05% cholic acid normalized the cholestanol levels in tendons and plasma and reduced the content in the brain. The above changes occurred in parallel with changes in plasma levels of 7alpha-hydroxy-4-cholesten-3-one, a precursor both to bile acids and cholestanol. Injection of a cyp27a1(-/-) mouse with (2)H(7)-labeled 7alpha-hydroxy-4-cholesten-3-one resulted in a significant incorporation of (2)H(7)-cholestanol in the brain. The results are consistent with a concentration-dependent flux of 7alpha-hydroxy-4-cholesten-3-one across the blood-brain barrier in cyp27a1(-/-) mice and subsequent formation of cholestanol. It is suggested that the same mechanism is responsible for accumulation of cholestanol in the brain of patients with CTX.

Cerebrotendinous xanthomatosis (CTX) is a rare neurodegenerative disorder with cholestanol accumulation resulting from mutations in the sterol 27-hydroxylase gene (CYP27A). Conventional treatment includes chenodeoxycholic acid and HMG-CoA reductase inhibitors. Mice with disrupted Cyp27A (Cyp27 KO) do not show elevated cholestanol levels nor develop CTX manifestations. This phenomenon was proposed to be due to murine CYP3A overexpression leading to an alternative pathway for degradation of bile alcohols including cholestanol. Our objective was to examine the influence of CYP3A4 induction on cholestanol elimination in CTX patients. Rifampicin (600 mg/day x 7 days), known to induce the PXR, and thereby to increase CYP3A activity, was used. The degree of CYP3A4 induction was assessed by comparing midazolam pharmacokinetics before and after rifampicin treatment. Cholestanol levels and cholestanol/cholesterol ratios were assayed during the experimental period and compared to a 3 weeks period without treatment. The results show that despite 60% increase in CYP3A4 activity following rifampicin treatment, there is no significant change in cholestanol levels. We conclude that up-regulated expression of CYP3A affects cholestanol elimination in mice differently as compared to its effect in CTX patients. Therefore, CYP3A4 inducers cannot replace chenodeoxycholic acid for the treatment of CTX.

Background and aim Hypercholesterolaemia is a major risk factor for atherosclerosis. Cholesterol is modulated by genetic and environmental factors. An important regulatory pathway is controlled by the sterol-regulatory element-binding proteins (SREBPs) and the SREBP cleavage-activating protein (SCAP). Both SREBP-2 and SCAP are candidates to contribute to the development of atherosclerosis. We investigated the possible effects of the variability of proteins involved in this regulatory pathway on plasma lipids among familial hypercholesterolaemia patients. Methods and results Single nucleotide polymorphisms (SNPs) in the genes encoding SREBP-2 and SCAP causing amino acid changes at positions 595 (595G/A) and 796 (796I/V), respectively, were genotyped in 801 FH individuals originating from Israel, The Netherlands, and Switzerland. A linear regression model to examine the associations between SREBP-2 and SCAP isoforms and lipid and lipoprotein levels was used. In females, homozygosity either for the SREBP-2-595A or for the SCAP-796I isoform was associated with higher LDL-cholesterol plasma concentrations (14.7mg/dl and 20.3mg/dl, respectively). Surprisingly, heterozygosity for the combination SREBP-2-595A/SCAP-796I was associated with a decrease of 30.28mg/dl in LDL-C ( p -value for gene–gene interaction=0.09). No such effect was observed among FH males. Subgroup analysis considering the most frequent ( N ≥24) LDL receptor mutations (del191−2, ins313+1−2, C660X, E207K, S285L) revealed further gene-dosage- and gender-dependent effects of the SCAP mutations on LDL-cholesterol concentrations ( p =0.0345). These effects were, however, not present when less frequent LDL receptor mutations were investigated. Conclusions These results suggest a possible gene–gene interaction between the genes encoding SREBP-2 and SCAP that modulate plasma lipids in a strictly gender-specific fashion. Further investigation is needed to confirm this effect. A study in a larger FH group or in non-FH hypercholesterolaemic subjects may further define the role of this regulatory mechanism in determining plasma lipid concentration.

Purpose Niemann-Pick disease type C (NP-C) is an autosomal recessive lipid storage disease manifested by an impairment in cellular cholesterol homeostasis. The clinical phenotype of NP-C is extremely variable, ranging from an acute neonatal form to an adult late-onset presentation. To facilitate phenotype-genotype studies, we have analyzed multiple Israeli NP-C families. Methods The severity of the disease was assessed by the age at onset, hepatic involvement, neurological deterioration, and cholesterol esterification studies. Screening of the entire NPC1 coding sequence allowed for molecular characterization and identification of disease causing mutations. Results A total of nine NP-C index cases with mainly neurovisceral involvement were characterized. We demonstrated a possible link between the severity of the clinical phenotype and the cholesterol esterification levels in fibroblast cultures following 24 hours of in vitro cholesterol loading. In addition, we identified eight novel mutations in the NPC1 gene. Conclusions Our results further support the clinical and allelic heterogeneity of NP-C and point to possible association between the clinical and the biochemical phenotype in distinct affected Israeli families.

Recent evidence suggests that sterol 27-hydroxylase may play a role in cholesterol homeostasis and affect atherogenesis. The major objective of the study was to map and characterize the sterol 27-hydroxylase (CYP27) promoter region. Here we show that CYP27 gene has a TATA-less promoter and transcription initiates at a cluster of sites. The basic promoter is located between −166 and −187 bp from the translation initiation site. Possible positive transcription regulation sites are located at position −187 to −320 and −857 to −1087 bp. A negative transcription regulator site is located in position −320 to −413 bp. An enhancer sequence is located upstream to position −1087. CYP27 is upregulated by dexamethasone and downregulated by cyclosporin A and cholic acid. The dexamethasone responsive element is located between 1087 and 678 bp upstream to the putative ATG. Cyclosporin A affects bile acid metabolism by repressing CYP27 at the transcriptional level. The cyclosporin A- responsive element is mapped to between 1087 and 4000 bp upstream of the ATG. Cholic acid represses sterol 27-hydroxylase mRNA level by affecting the stability of its mRNA. The results obtained here imply that CYP27 has a potentially important role in cholesterol homeostasis in human cells, and is regulated by several substances that were previously shown to affect bile acid metabolism.

Cerebrotendinous xanthomatosis is characterized by the accumulation of cholestanol and cholesterol in xanthomas and brain causing a number of severe symptoms. More than 20 different mutations have been identified in the gene encoding sterol 27-hydroxylase. Defects in the gene lead to reduced bile acid biosynthesis, with accumulation of 7 alpha-hydroxylated intermediates, one of which is a precursor to cholestanol. The disease can be treated successfully with chenodeoxycholic acid, which reduces the upregulation of cholesterol 7 alpha-hydroxylase and, therefore, the formation of cholestanol. Disruption of the gene encoding sterol 27-hydroxylase in mice does not have the same metabolic consequences as in humans.

Based on the demand for cholesterol for membrane formation, we determined the ability of low-density lipoprotein (LDL) to support proliferation in lymphocytes bearing different LDL receptor mutations, which were treated "in vitro" with lovastatin to inhibit endogenous cholesterol synthesis. Peripheral lymphocytes were isolated from two patients with homozygous familial hypercholesterolemia (FH), one homozygote for the mutation N804K (FH(Colmenar)) in exon 17, herein described for the first time, and a compound heterozygote carrying the mutations D280G and G528V, which determine a transport-defective biochemical phenotype. Flow cytometric analysis with 1,1'-dioctadecyl-3,3,3,3'-tetramethylindocarbocyanineperchlorate (Dil)-LDL showed normal LDL binding but defective internalization in lymphocytes from case 1, whereas in lymphocytes from case 2 both LDL binding and internalization were affected. Studies with mitogen-stimulated lymphocytes demonstrated that despite the different phenotype, the ability of LDL to support proliferation was impaired in both cases to a similar extent. These results indicate that internalization of the LDL particle is required for expression of the mitogenic effect of LDL.

Familial hypercholesterolemia carries a markedlyincreased risk of coronary artery disease. Reduction of plasma low density lipoprotein cholesterol (LDL-C) levels to the normal range may prevent premature atherosclerosis and usually requires a combination of cholesterol-lowering drugs such as 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors plus resins or fibrates. The current, 60-week, open-label investigation involved 22 patients whose plasma LDL-C had not reached the target level for prevention of coronary artery disease in 3 previous studies using fluvastatin alone and in combination with other cholesterol-lowering medications. At the beginning of the current study, patients were stabilized on fluvastatin monotherapy at 40 mg/day. After 6 weeks, the daily treatment changed to a combination of fluvastatin 40 mg/day in the evening and bezafibrate 400 mg/day in the morning. After a further 6 weeks, a lunchtime dose of cholestyramine 8 g/day was added, to form triple cholesterol-lowering therapy. Efficacy was determined by plasma lipid/lipoprotein analysis. Baseline levels were assessed after 4 weeks of placebo treatment, prior to active treatment, in the first fluvastatin study. Safety analyses included liver and renal function tests, creatine phosphokinase levels and blood counts. Compliance was determined by counting the fluvastatin capsules, bezafibrate tablets, and cholestyramine sachets returned by the patients at each visit. The triple-drug combination used in this study was more effective than the double therapy and resulted in stabilization of the LDL-C:high density lipoprotein cholesterol (HDL-C) ratio, at a reduction from baseline ranging from −40.4 to −52.5%. After initiation of triple therapy, LDL-C levels were maintained at

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid-storage disease caused by mutations in the sterol 27-hydroxylase gene (CYP27). So far several mutations causing CTX have been identified and characterized. A new mutation creating an insertion of cytosine at position 6 in the cDNA, which is expected to result in a frameshift and a premature termination codon at codon 179, has been identified in a French family. The mutation creates a new site for the restriction endonuclease HaeIII.

The possible role of four candidate genes in lipid and lipoprotein response to diet was examined in 63 male students. Four site polymorphisms (signal peptide insertion/deletion, XbaI, MspI and EcoRI) of the apo B gene, three RFLPs (AvaII, StuI, and HincII) of the LDL receptor gene, two SSCPs of the cholesterol 7 alpha-hydroxylase gene and the common apo E genotypes were determined. The average reductions induced by diet in participants homozygous for the absence of the XbaI restriction site (X-X-) of the apo B gene compared to those harboring this site (X+) were: 14.5 mg/dl and 9.4 mg/dl for total cholesterol (TC) (p < 0.09) and 15.5 mg/dl and 7.9 mg/dl for LDL-C (p < 0.003), respectively. Differences in dietary responsiveness among the apo E, LDL receptor and the cholesterol 7 alpha-hydroxylase genotypes were largely insignificant. Using the four apo B polymorphic sites, six unambiguous haplotypes were constructed and a model for their possible evolutionary relationship is presented. Genetic variation in the apo B gene region, as defined by haplotypes, accounted for 8.7% and 24.3% of the phenotypic variance in TC and LDL-C response to diet, respectively. Sequence analysis of a candidate locus, the putative LDL receptor binding region of apo B and its flanking sequences, was performed in two individuals, one homozygous for an apo B "hyper-responding" and another for the "lower-responding" haplotype, and no differences were found. In conclusion, haplotypes at the apo B gene locus are associated with dietary response of TC and LDL-C in young males. Yet, the sequence variation responsible for these differences is possibly located outside the putative LDL receptor binding domain.

A recent randomized, double-blind, double-dummy trial revealed differences in the response of patients with heterozygous familial hypercholesterolemia to combination therapy with the new, wholly synthetic 3-hydroxy-3-methylglutarylcoenzyme A (HMG-CoA) reductase inhibitor fluvastatin, 20 mg/day and then 40 mg/day, plus the fibric acid analogue bezafibrate, 400 mg/day, vs combination therapy wtth fluvastatin, 40 mg/day, plus the bile acid sequestrant (resin) cholestyramine, 8 g/day. The main purpose of the present cohort analysis was to determine whether these differences in lipid response were related to imbalances in the patients' prior responses to up to 42 weeks of fluvastatin monotherapy, 20 mg/day, 40 mg/day, and, in some patients, 60 mg/day, in 2 earlier studies. For the present analysis, we identified 18 patients in the fluvastatin plus bezafibrate group (cohort 1) and 16 patients in the fluvastatin plus cholestyramine group (cohort 2) for whom complete dose-response data were available for the full 56-week duration of all 3 studies. Subsets of 7 patients in cohort 1 and 8 patients in cohort 2 had received the 60 mg/day fluvastatin dose during a previous monotherapy study. In cohort 1, low density lipoprotein cholesterol (LDL-C) decreased by 19% with 20 mg/day fluvastatin, by 27% with 40 mg/day fluvastatin, by 31% with 20 mg/day fluvastatin plus bezafibrate, and by 35% with 40 mg/day fluvastatin plus bezafibrate, and the LDL-C/high density lipoprotein cholesterol (HDL-C) ratio had fallen by 46% at the end of combination therapy. In cohort 2, LDL-C declined by 19% with 20 mg/day fluvastatin, by 23% with 40 mg/day fluvastatin, and by 31% with fluvastatin plus cholestyramine, and the LDL-C HDL-C ratio was lowered by 38% at the combination therapy endpoint. Thus, the LDL-C response was similar in both cohorts, except for the enhancement of the effect on the LDL-C HDL-C ratio seen with the combination of fluvastatin plus bezafibrate, compared with the combination of fluvastatin plus cholestyramine. That is, the addition of either bezafibrate or cholestyramine lowered LDL-C levels by an additional 9–10% relative to the decreases achieved with 40 mg/day fluvastatin alone. According to the findings of the cohort analysis, some of the differences in efficacy observed between the 2 combination regimens were related to prior response to monotherapy, which, in turn, may have reflected patient gender and/or compliance with therapy. No clinically meaningful abnormalities in aspartate aminotransferase, alanine aminotransferase, or creatine kinase levels were noted with either combination regimen, which suggests that the regimens were equally safe. Although both combinations were effective, fluvastatin plus bezafibrate appeared to be superior, since it lowered triglyceride levels by 24%, in contrast to the 8% increase seen with fluvastatin plus cholestyramine. We conclude that the combination of fluvastatin with bezafibrate is a good alternative for the treatment of severe familial hypercholesterolomia when a fluvastatin-resin combination is poorly tolerated and/or does not achieve goal lipid levels. However, careful monitoring is recommended in light of reports of the development of myopathy and rhabdomyolysis with the use of fibrates alone or in combination with other fungally derived HMG-CoA reductase inhibitors.

purpose: Familial hypercholesterolemia (FH) carries a markedly increased risk for coronary artery disease (CAD). Reduction of plasma low-density lipoprotein cholesterol (LDL-C) levels to the normal range may prevent premature atherosclerosis and usually requires a combination of cholesterol-lowering drugs. The major objective of this study is to compare two different drug combinations for the treatment of heterozygous FH. patients and methods: The current investigation is a short-term, double-blind study comparing the efficacy and safety of fluvastatin when combined with cholestyramine (group 1) or with bezafibrate (group 2) in 38 patients with heterozygous FH. results: After 6 weeks of combination treatment, in comparison to a drug-free baseline (patients receiving single-blind placebo during the lead-in period of an earlier study, ie, before ever receiving fluvastatin), the combination of 40 mg/d of fluvastatin with 400 mg/d of bezafibrate in group 2 reduced plasma LDL-C levels by 35% as compared with 32% in group 1, and reduced the LDL-C/high-density cholesterol (HDL-C) ratio by 46%, compared to 37% in group 1 (a non-significant difference for both comparisons). When compared to an intermittent 6-week open-label administration of 40 mg fluvastatin monotherapy, the addition of cholestyramine or bezafibrate each reduced LDL-C by an additional 13% (P conclusions: Fluvastatin-bezafibrate is superior to a fluvastatin-Cholestyramine combination for lowering serum triglycerides and elevating HDL-C serum levels in patients in conjunction with a significant lowering of LDL-C/HDL-C ratios, and may be an effective synergistic therapy for heterozygous FH. No episodes of myositis were seen in this short-term study, a finding that is in agreement with most of the reported studies on statin-fibrate combinations reviewed here.

South Africans of Indian origin have a high frequency of Familial Hypercholesterolemia (FH). Fibroblasts from a South African Indian FH homozygote, D, expressed about 30% of the normal number of LDL receptors. These receptors showed defective LDL binding. Sequence and haplotype analysis revealed that D had two different mutant LDL receptor alleles: FH Durban-1 is a point mutation [asp 69 (GAT) to tyr(TAT)] in ligand-binding repeat 2 and FH Durban-2 is a point mutation [glu 119 GAG) to lys(AAG)] in ligand-binding repeat three of the LDL receptor. Single-strand conformational polymorphism analysis, which was used in the initial detection of these mutations, was also employed for subsequent population screening assays. These mutations were not detected in amy of the South African Indian FH of hypercholesterolemic patients that were screened.

Familial hypercholesterolemia (FH) is an autosomal dominant disease caused by mutations in the low density lipoprotein (LDL) receptor gene. Here, we characterize an LDL receptor mutation that is associated with a distinct haplotype and that causes FH in the Jewish Sephardic population originating from Safed, a town in northern Israel. The mutation was found in eight FH families originating from this community comprising 10% of heterozygote FH index cases screened in Israel. The mutation was not found in four additional FH heterozygotes whose hypercholesterolemia co-segregated with an identical LDL receptor gene haplotype. A guanine to cytosine substitution results in a missense mutation (asp147 to his) in the fourth repeat of the binding domain encoded by exon 4 of the LDL receptor gene. The mutant receptor protein was synthesized in cultured cells as a 120 kDa precursor form that failed to undergo normal processing to a mature cell surface form. Most of the receptor precursors were degraded in the endoplasmic reticulum. The small number of mutant receptors on the cell surface were unable to bind LDL or beta very low density lipoprotein. The abnormal behavior of the mutant receptor was reproduced by site-directed mutagenesis and expression of the mutant protein in CHO cells. The mutation can be diagnosed by allele-specific oligonucleotide hybridization of polymerase chain reaction amplified DNA from FH patients.

Regulation of lipoprotein lipase was studied in mesenchymal rat heart-cell cultures. Treatment of the cultures with dibutyryl cyclic AMP or with cholera toxin resulted in an increase in LPL activity and a comparable increase in LPL mRNA. When the cells were exposed to 100 mM Hepes for 24 h, total enzyme activity rose 2-folf and LPL mRNA increased 2.4-fold. After 72 h, there was a 3-fold increase in LPL mRNA and a 4-fold rise in cellular LPL activity, while medium activity increased 20-fold. Exposure of the cultures to heparin for 24 h resulted in a 3.2-fold increase in total activity and a 36-fold increase in medium activity. This increase was not accompanied by any rise in LPL mRNA. Addition of actinomycin D to control dishes for 24 h resulted in a 33% reduction in LPL mRNA and a 43% reduction in enzyme activity. These values were 71% and 56%, respectively, in Hepes-treated cells, indicating that no stabilization of LPL mRNA occurred under these conditions. It can be concluded that in mesenchymal rat heart-cells in culture cAMP and cholera toxin upregulate lipoprotein lipase at the level of transcription. The increase in LPL activity after 24 h exposure to Hepes could be compatible with transcriptional regulation, while exposure to heparin is not accompanied by a change in LPL mRNA.

Here, we report the prenatal diagnosis of familial hypercholesterolemia in a Christian-Arab family that carries the "Lebanese" mutation, a single base substitution that creates a HinfI restriction site, at the low density lipoprotein (LDL) receptor locus. Polymerase chain reaction amplification and restriction analysis were performed on genomic DNA extracted from a chorionic villus sample. In conjunction with karyotype analysis, the fetus was identified as a heterozygous female. Analysis of LDL receptor restriction fragment length polymorphisms confirmed the presence of a male parent marker and revealed that the fetus inherited the mutant gene from its mother. This technique offers a simple and rapid diagnostic tool that can be carried out at an early stage of gestation. It is recommended for families and population groups with molecularly defined LDL receptor mutations.

Familial hypercholesterolemia (FH) results from mutations in the low density lipoprotein (LDL) receptor gene. It has been shown that restriction fragment length polymorphisms (RFLPs) associated with this gene may be used for family and population studies. The present investigation is a population-based study of 19 Jewish families with hypercholesterolemia representing 9 different countries of origin. Ten RFLP sites were used to construct 24 different haplotypes from 112 chromosomes. These haplotypes vary in frequency from 0.9% to 28.6%. Five previously undescribed haplotypes, which comprise 8.1% of the sample, are reported here. The six most common haplotypes account for 70% of the sample. Segregation analysis reveals that, in Israel, distinct LDL receptor haplotypes are associated with hypercholesterolemia in 12 (63%) out of the 19 Jewish families. Five LDL receptor haplotypes co-segregate with hypercholesterolemia. Two of these haplotypes seem to be unique to specific population groups in Israel and may therefore represent founder mutations.

Segregation analyses were performed for plasma low density lipoprotein cholesterol (LDL-C), triglycerides (TG) and high density lipoprotein cholesterol (HDL-C) in five Christian Arab kindreds identified through probands with familial hypercholesterolemia. In this subset of the Christian Arab community, the results were consistent with major gene determination of LDL-C with allele frequency (q) of 0.042 (95% confidence interval 0.008–0.079) in addition to polygenic transmission (h 2= 0.34). The “Lebanese” allele was identified directly by polymerase chain reaction and HinfI restriction analysis. Analysis of this mutation permits direct diagnosis of familial hypercholesterolemia in most affected individuals although our results indicated the possible existence of an additional independent factor leading to elevated LDL-C levels. The segregation results for TG indicated the presence of a major effect, although the existence of a major gene could not be demonstrated. There was also no evidence of a major locus effect on HDL-C levels.

Plasma lipids, lipoproteins, and lipoprotein[a] (Lp[a]) levels were determined in 216 members of 14 families with familial hypercholesterolemia (FH). Ninety-nine subjects harbored a mutant low density lipoprotein (LDL) receptor allele as confirmed by molecular genetic analysis. Four different mutant alleles were identified, each in a defined genetic group, Druze, Christian-Arabs, and Ashkenazi and Sephardic Jews. The findings in FH subjects (cases) were compared with their nonaffected family members (controls). Plasma Lp[a] levels increased with age in the controls but not in cases and were different among the four genetic groups. Mean plasma Lp[a] levels were significantly higher in cases (33 mg/dl) than in controls (22 mg/dl). Plasma LDL cholesterol levels were raised in cases of the four genetic groups to a similar extent, in contrast to the mean plasma Lp[a] that varied. The Lp[a] level was higher by 30-33% in cases from the Druze, Christian-Arabs, and Jewish-Ashkenazi groups but by 110% in the Jewish-Sephardic group. Apo[a] isoform distribution was similar in cases and controls within each genetic group. Lp[a] levels were highest in subjects with LpS1 isoform, in particular in cases from the Jewish-Sephardic group. These data indicate that the higher Lp[a] levels in FH heterozygotes cannot be attributed solely to lack of functional LDL receptor molecules but possibly reflect multiple gene interactions.