STARD1 promotes NASH-driven HCC by sustaining the generation of bile acids through the alternative mitochondrial pathway.

BACKGROUND & AIMS: Besides their physiological role in bile formation and fat digestion, bile acids (BAs) synthesised from cholesterol in hepatocytes act as signalling molecules that modulate hepatocellular carcinoma (HCC). Trafficking of cholesterol to mitochondria through steroidogenic acute regulatory protein 1 (STARD1) is the rate-limiting step in the alternative pathway of BA generation, the physiological relevance of which is not well understood. Moreover, the specific contribution of the STARD1-dependent BA synthesis pathway to HCC has not been previously explored. METHODS: STARD1 expression was analyzed in a cohort of human non-alcoholic steatohepatitis (NASH)-derived HCC specimens. Experimental NASH-driven HCC models included MUP-uPA mice fed a high-fat high-cholesterol (HFHC) diet and diethylnitrosamine (DEN) treatment in wild-type (WT) mice fed a HFHC diet. Molecular species of BAs and oxysterols were analyzed by mass spectrometry. Effects of NASH-derived BA profiles were investigated in tumour-initiated stem-like cells (TICs) and primary mouse hepatocytes (PMHs). RESULTS: Patients with NASH-associated HCC exhibited increased hepatic expression of STARD1 and an enhanced BA pool. Using NASH-driven HCC models, STARD1 overexpression in WT mice increased liver tumour multiplicity, whereas hepatocyte-specific STARD1 deletion (Stard1ΔHep) in WT or MUP-uPA mice reduced tumour burden. These findings mirrored the levels of unconjugated primary BAs, ß-muricholic acid and cholic acid, and their tauroconjugates in STARD1-overexpressing and Stard1ΔHep mice. Incubation of TICs or PMHs with a mix of BAs mimicking this profile stimulated expression of genes involved in pluripotency, stemness and inflammation. CONCLUSIONS: The study reveals a previously unrecognised role of STARD1 in HCC pathogenesis, wherein it promotes the synthesis of primary BAs through the mitochondrial pathway, the products of which act in TICs to stimulate self-renewal, stemness and inflammation. LAY SUMMARY: Effective therapy for hepatocellular carcinoma (HCC) is limited because of our incomplete understanding of its pathogenesis. The contribution of the alternative pathway of bile acid (BA) synthesis to HCC development is unknown. We uncover a key role for steroidogenic acute regulatory protein 1 (STARD1) in non-alcoholic steatohepatitis-driven HCC, wherein it stimulates the generation of BAs in the mitochondrial acidic pathway, the products of which stimulate hepatocyte pluripotency and self-renewal, as well as inflammation.

Effect of bergamot on lipid profile in humans: A systematic review.

Dyslipidemia is a well-established modifiable cardiovascular risk. Although statins can reduce LDLc by 50-60%, less than 20% of patients with high risk of CVD achieve LDL targets. The aim of this systematic review is to evaluate the effect of the nutraceutical, bergamot (Citrus bergamia), on lipid parameters in humans. PubMed, Embase, Cochrane Library, and Google Scholar databases were searched for interventional and observational studies investigating the effect of bergamot on lipid profile in humans. This systematic review retrieved a total of 442 studies of which 12 articles fulfilled the eligibility criteria and were included in the qualitative synthesis. Based on data, 75% of studies showed a significant decrease in total cholesterol, triglycerides and LDLc. The decrease in total cholesterol varied from 12.3% to 31.3%, from 7.6% to 40.8% in LDLc and from 11.5% to 39.5% in triglycerides. Eight trials reported HDLc increase after intervention with bergamot. Overall, a dose-dependent and possible synergistic effect when administering with statins can be deducted from these trials. It is essential to point out that studies had heterogeneous designs and scientific quality of studies was quite limited. Promising findings reveal an alternative therapeutic option in dyslipidemia management with bergamot supplementation, especially in subjects with statins intolerance.

Association between non-cholesterol sterol concentrations and Achilles tendon thickness in patients with genetic familial hypercholesterolemia.

BACKGROUND: Familial hypercholesterolemia (FH) is a genetic disorder that result in abnormally high low-density lipoprotein cholesterol levels, markedly increased risk of coronary heart disease (CHD) and tendon xanthomas (TX). However, the clinical expression is highly variable. TX are present in other metabolic diseases that associate increased sterol concentration. If non-cholesterol sterols are involved in the development of TX in FH has not been analyzed. METHODS: Clinical and biochemical characteristics, non-cholesterol sterols concentrations and Aquilles tendon thickness were determined in subjects with genetic FH with (n = 63) and without (n = 40) TX. Student-t test o Mann-Whitney test were used accordingly. Categorical variables were compared using a Chi square test. ANOVA and Kruskal-Wallis tests were performed to multiple independent variables comparison. Post hoc adjusted comparisons were performed with Bonferroni correction when applicable. Correlations of parameters in selected groups were calculated applying the non-parametric Spearman correlation procedure. To identify variables associated with Achilles tendon thickness changes, multiple linear regression were applied. RESULTS: Patients with TX presented higher concentrations of non-cholesterol sterols in plasma than patients without xanthomas (P = 0.006 and 0.034, respectively). Furthermore, there was a significant association between 5α-cholestanol, ß-sitosterol, desmosterol, 24S-hydroxycholesterol and 27-hydroxycholesterol concentrations and Achilles tendon thickness (p = 0.002, 0.012, 0.020, 0.045 and 0.040, respectively). CONCLUSIONS: Our results indicate that non-cholesterol sterol concentrations are associated with the presence of TX. Since cholesterol and non-cholesterol sterols are present in the same lipoproteins, further studies would be needed to elucidate their potential role in the development of TX.

Frequency of rare mutations and common genetic variations in severe hypertriglyceridemia in the general population of Spain.

BACKGROUND: Hypertriglyceridemia (HTG) is a common complex metabolic trait that results of the accumulation of relatively common genetic variants in combination with other modifier genes and environmental factors resulting in increased plasma triglyceride (TG) levels. The majority of severe primary hypertriglyceridemias is diagnosed in adulthood and their molecular bases have not been fully defined yet. The prevalence of HTG is highly variable among populations, possibly caused by differences in environmental factors and genetic background. However, the prevalence of very high TG and the frequency of rare mutations causing HTG in a whole non-selected population have not been previously studied. METHODS: The total of 23,310 subjects over 18 years from a primary care-district in a middle-class area of Zaragoza (Spain) with TG >500 mg/dL were selected to establish HTG prevalence. Those affected of primary HTG were considered for further genetic analysis. The promoters, coding regions and exon-intron boundaries of LPL, LMF1, APOC2, APOA5, APOE and GPIHBP1 genes were sequenced. The frequency of rare variants identified was studied in 90 controls. RESULTS: One hundred ninety-four subjects (1.04%) had HTG and 90 subjects (46.4%) met the inclusion criteria for primary HTG. In this subgroup, nine patients (12.3%) were carriers of 7 rare variants in LPL, LMF1, APOA5, GPIHBP1 or APOE genes. Three of these mutations are described for the first time in this work. The presence of a rare pathogenic mutation did not confer a differential phenotype or a higher family history of HTG. CONCLUSION: The prevalence of rare mutations in candidate genes in subjects with primary HTG is low. The low frequency of rare mutations, the absence of a more severe phenotype or the dominant transmission of the HTG would not suggest the use of genetic analysis in the clinical practice in this population.

Bile acid synthesis precursors in familial combined hyperlipidemia: the oxysterols 24S-hydroxycholesterol and 27-hydroxycholesterol.

Familial combined hyperlipidemia (FCHL), the most common inherited disorder of lipid metabolism is characterized by increasing cholesterol synthesis precursors due to hepatic overproduction of cholesterol. The bile acids synthesis pathway has not been previously studied in FCHL. The aim of this work was to study the oxysterol levels which are involved in the bile acids synthesis from cholesterol in FCHL. Clinical parameters and subclinical atherosclerosis were studied in a total of 107 FCHL patients and 126 normolipidemic controls. Non cholesterol sterols (desmosterol and lanosterol) and oxysterols (27-hydroxycholesterol and 24S-hydroxycholesterol) were measured by high performance liquid chromatography tandem mass spectrometry. Desmosterol and lanosterol, markers of cholesterol synthesis, had a positive correlation with BMI and apo B. However, no correlation was found for 24S-hydroxycholesterol and 27-hydroxycholesterol, precursors of bile acids, with these clinical parameters. Only 27-hydroxycholesterol had a positive correlation with apo B, ρ=0.204 (P=0.037). All oxysterol levels were higher in FHCL as compared to normal controls. A total of 59 FCHL subjects (59%) presented values of 24S-hydroxycholesterol above the 95th percentile of this oxysterol in the control population. All oxysterols showed no association with fat mass in contrast with non-cholesterol sterols. FCHL subjects with oxysterol overproduction had less carotid intima media thickness (cIMT), which suggests less atherosclerosis in these subjects. In summary, our data indicate that high oxysterol levels might be good markers of FCHL, unrelated to fat mass, and may exert a protective mechanism for cholesterol accumulation.

Serum lipid responses to weight loss differ between overweight adults with familial hypercholesterolemia and those with familial combined hyperlipidemia.

The effect of weight loss on lipids differs among individuals, although whether it can modify the management of hereditary hyperlipidemias has not yet been explored. The objective of this study was to examine the effect of weight loss on cholesterol metabolism, assessed by circulating noncholesterol sterols, in overweight adults with familial hypercholesterolemia (FH) and familial combined hyperlipidemia (FCHL). We conducted a 6-mo weight loss intervention in untreated individuals (FH: n = 28; FCHL: n = 50) with a body mass index of >25 kg/m(2) and mean age of 46.9 ± 11.3 y, of whom 53.8% were men. A hypocaloric diet was implemented and serum lipid analyses, including noncholesterol sterols, were assessed. Global significant mean weight losses of 5.7 kg (-6.6%) and 6.6 kg (-7.6%) were achieved after 3 and 6 mo, respectively. Mean non-HDL cholesterol and triglyceride (TG) changes at 3 and 6 mo compared with baseline were -5.8% (P = 0.004) and -7.1% (P = 0.014), and -30.1% (P < 0.001) and -31.4% (P < 0.001), respectively. Among participants who lost ≥5% body weight, only significant changes in TGs and non-HDL cholesterol were observed in FCHL participants. Sterol precursors of cholesterol synthesis decreased significantly by 10.4% at 6 mo in FCHL participants, mostly because of a 23.9% lathosterol reduction. Baseline synthesis precursors were associated with TG reduction in FCHL participants (P = 0.039; R(2) = 0.20), and intestinally derived sterols were inversely associated with non-HDL cholesterol changes in FH participants (P = 0.036; R(2) = 0.21). Thus, FCHL participants had a better lipid-lowering response to weight loss than did FH participants. This response was positively associated with baseline cholesterol synthesis, which was reduced by weight loss. Our results confirm the cholesterol overproduction mechanism of FCHL and its interaction with fat mass, while also supporting the differential management of familial hyperlipidemias if obesity coexists. This trial was registered at clinicaltrials.gov as NCT01995149.

Association of Cholesterol and Oxysterols in Adipose Tissue With Obesity and Metabolic Syndrome Traits.

OBJECTIVE: Adipose tissue stores a substantial amount of body cholesterol in humans. Obesity is associated with decreased concentrations of serum cholesterol. During weight gain, adipose tissue dysfunction might be one of the causes of metabolic syndrome. The aim of this study is to evaluate cholesterol storage and oxidized metabolites in adipose tissue and their relationship with metabolic clinical characteristics. METHODS: Concentrations of cholesterol and oxysterols (27-hydroxycholesterol and 24S-hydroxycholesterol) in subcutaneous and visceral adipose tissue were determined by high-performance liquid chromatography with tandem mass spectrometry in 19 adult women with body mass index between 23 and 40 kg/m2 from the FAT expandability (FATe) study. Tissue concentration values were correlated with biochemical and clinical characteristics using nonparametric statistics. RESULTS: Insulin correlated directly with 24S-hydroxycholesterol in both adipose tissues and with 27-hydroxycholesterol in visceral tissue. Leptin correlated directly with 24S-hydroxycholesterol in subcutaneous adipose tissue. Tissue cholesterol correlated directly with 27-hydroxycholesterol in both adipose tissues and with 24S-hydroxycholesterol in visceral tissue, where cholesterol correlation with 24S-hydroxycholesterol was higher than with 27-hydroxycholesterol. In addition, some tendencies were observed: serum high-density lipoprotein cholesterol tended to be inversely correlated with visceral adipose tissue cholesterol; high-sensitivity C-reactive protein tended to be correlated directly with subcutaneous adipose 24S-hydroxycholesterol and inversely with visceral 27-hydroxycholesterol. CONCLUSIONS: Adipose tissue oxysterols are associated with blood insulin and insulin resistance. Tissue cholesterol correlated more with 27-hydroxycholesterol in subcutaneous adipose tissue and with 24S-hydroxycholesterol in visceral adipose tissue. Levels of adipose 24S-hydroxycholesterol seem to be correlated with some metabolic syndrome symptoms and inflammation while adipose 27-hydroxycholesterol could represent some protection against them.

The effects of high-intensity interval training on glucose metabolism, cardiorespiratory fitness and weight control in subjects with diabetes: Systematic review a meta-analysis.

AIM: The objective of this meta-analysis was to explore the effects of high-intensity interval training (HIIT) compared with control conditions (CON) or moderate intensity continuous training (MICT) on glycemic parameters in diabetes subjects. METHODS: Pubmed, Embase and Google Scholar databases were searched for HIIT interventions that were carried out in diabetic subjects and exploring fasting glucose, glycated haemoglobin (HbA1c), fasting insulin and/or HOMA-IR. RESULTS: This systematic review retrieved a total of 1741 studies of which 32 articles fulfilled the eligibility criteria. Nineteen trials were included in the meta-analysis since they compared HIIT intervention with CON or MICT group. There was a significantly reduction of fasting glucose of 13.3 mg/dL (p < 0.001), Hb1Ac -0.34% (p < 0.001), insulin -2.27 UI/L (p = 0.003), HOMA-IR -0.88 (p = 0.005) in the HIIT-group compared with CON-group. Nevertheless, this reduction was not significantly different when comparing HIIT with MICT (p = 0.140, p = 0.315, p = 0.520 and p = 0.389). Besides, there was a significant increase of absolute VO2max of 0.21 L/min (p < 0.001) and relative VO2max of 2.94 ml/kg/min (p < 0.001) in the HIIT-group compared with the CON-group and the MICT-group (0.22 L/min, p = 0.025) and (0.97 ml/kg/min, p = 0.045). CONCLUSIONS: These findings revealed that HIIT intervention led to significant improvement in glycemic control and insulin resistance in subjects with diabetes compared with CON-group.

Gene supplementation of CYP27A1 in the liver restores bile acid metabolism in a mouse model of cerebrotendinous xanthomatosis.

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive disease caused by mutations in the CYP27A1 gene, encoding the sterol 27-hydroxylase. Disruption of the bile acid biosynthesis pathway and accumulation of toxic precursors such as cholestanol cause chronic diarrhea, bilateral juvenile cataracts, tissue deposition of cholestanol and cholesterol (xanthomas), and progressive motor/neuropsychiatric alterations. We have evaluated the therapeutic potential of adeno-associated virus (AAV) vectors expressing CYP27A1 in a CTX mouse model. We found that a vector equipped with a strong liver-specific promoter (albumin enhancer fused with the α1 anti-trypsin promoter) is well tolerated and shows therapeutic effect at relatively low doses (1.5 × 1012 viral genomes [vg]/kg), when less than 20% of hepatocytes overexpress the transgene. This vector restored bile acid metabolism and normalized the concentration of most bile acids in plasma. By contrast, standard treatment (oral chenodeoxycholic acid [CDCA]), while reducing cholestanol, did not normalize bile acid composition in plasma and resulted in supra-physiological levels of CDCA and its derivatives. At the transcriptional level, only the vector was able to avoid the induction of xenobiotic-induced pathways in mouse liver. In conclusion, the overexpression of CYP27A1 in a fraction of hepatocytes using AAV vectors is well tolerated and provides full metabolic restoration in Cyp27a1 -/- mice. These features make gene therapy a feasible option for the etiological treatment of CTX patients.

High-protein energy-restricted diets induce greater improvement in glucose homeostasis but not in adipokines comparing to standard-protein diets in early-onset diabetic adults with overweight or obesity.

BACKGROUND & AIMS: It has not been elucidated if an energy-restricted diet with high protein content could induce a benefit in insulin resistance in subjects with type 2 diabetes (T2DM); and if an adipose tissue functionality improvement could mediate this effect. We aimed to assess the effect of energy-restricted diets with standard (18% from total calories; SP) vs high (35%) protein (HP), mainly coming from lean animal source, composition on glucose metabolism and adipokine concentration in overweight and obese subjects with T2DM. HOMA-IR change was the primary outcome. METHODS: Six-month weight-loss intervention including 73 subjects (43.8% men, 55.6 ± 8.37 aged and 32.8 ± 3.67 of BMI) with T2DM that were randomized to follow one of two calorie-restricted diets with the following distribution of calories: 18% (0.75 [95%CI: 0.71-0.78] g/kg/day) protein, 52% carbohydrates and 30% fat, or 35% (1.34 [95%CI: 1.27-1.41] g/kg/day) protein, 35% carbohydrates, and 30% fat. Anthropometric, clinical, biochemical (involving leptin, RBP4 and adiponectin) and lifestyle assessments were performed. RESULTS: Sixty-seven participants completed the study. Weight loss homogenously decreased among diets. HOMA-IR in HP diminished 2-fold than in SP diet (P = 0.023 and P = 0.004 at 3 and 6-months between diets). Participants following HP diet showed higher decrease in insulin, in glucose at 6-months (P = 0.004) and in HbA1c at 3-months (P = 0.003). RBP4 and leptin significantly decreased in both diets although no differences were found between diets. Adiponectin increased by 6.05% and 29.9% at 3-months in SP and HP diets, respectively (P = 0.167), and 23.7% and 53.5% at 6-months in SP and HP diets (P = 0.219). Adiponectin variation was inversely correlated with HbA1c, insulin and HOMA-IR changes at 6-months. CONCLUSIONS: An energy-restricted diet containing 35% of total calories coming from protein lead to a greater improvement in glucose homeostasis, indicated by HOMA-IR and fasting plasma insulin concentrations, irrespective of weight loss in subjects with prediabetes or early stages of T2DM. This effect cannot be explained by changes in plasma concentration of adipokines. CLINICAL TRIAL REGISTRATION: The clinical trial has been registered in ClinicalTrials.gov (Identifier: NCT02559479).

Genetic predictors of weight loss in overweight and obese subjects.

The aim of our study was to investigate a large cohort of overweight subjects consuming a homogeneous diet to identify the genetic factors associated with weight loss that could be used as predictive markers in weight loss interventions. We retrospectively recruited subjects (N = 788) aged over 18 years with a Body Mass Index (BMI) between 25 and 40 kg/m2 who were treated at our lipid unit for at least one year from 2008 to 2016, and we also recruited a control group (168 patients) with normal BMIs. All participants received counselling from a nutritionist that included healthy diet and physical activity recommendations. We genotyped 25 single nucleotide variants (SNVs) in 25 genes that were previously associated with obesity and calculated genetic scores that were derived from 25 SNVs. The risk allele in CADM2 showed a higher frequency in overweight and obese subjects than in controls (p = 0.007). The mean follow-up duration was 5.58 ± 2.68 years. Subjects with lower genetic scores showed greater weight loss during the follow-up period. The genetic score was the variable that best explained the variations in weight from the baseline. The genetic score explained 2.4% of weight change variance at one year and 1.6% of weight change variance at the end of the follow-up period after adjusting for baseline weight, sex, age and years of follow-up.

Cholesterol and 27-hydroxycholesterol promote thyroid carcinoma aggressiveness.

Cholesterol mediates its proliferative and metastatic effects via the metabolite 27-hydroxycholesterol (27-HC), at least in breast and endometrial cancer. We determined the serum lipoprotein profile, intratumoral cholesterol and 27-HC levels in a cohort of patients with well-differentiated papillary thyroid carcinoma (PTC; low/intermediate and high risk), advanced thyroid cancers (poorly differentiated, PDTC and anaplastic thyroid carcinoma, ATC) and benign thyroid tumors, as well as the expression of genes involved in cholesterol metabolism. We investigated the gene expression profile, cellular proliferation, and migration in Nthy-ori 3.1 and CAL-62 cell lines loaded with human low-density lipoprotein (LDL). Patients with more aggressive tumors (high-risk PTC and PDTC/ATC) showed a decrease in blood LDL cholesterol and apolipoprotein B. These changes were associated with an increase in the expression of the thyroid's LDL receptor, whereas 3-hydroxy-3-methylglutaryl-CoA reductase and 25-hydroxycholesterol 7-alpha-hydroxylase were downregulated, with an intratumoral increase of the 27-HC metabolite. Furthermore, LDL promoted proliferation in both the Nthy-ori 3.1 and CAL-62 thyroid cellular models, but only in ATC cells was its cellular migration increased significantly. We conclude that cholesterol and intratumoral accumulation of 27-HC promote the aggressive behavior process of PTC. Targeting cholesterol metabolism could be a new therapeutic strategy in thyroid tumors with poor prognosis.

First international descriptive and interventional survey for cholesterol and non-cholesterol sterol determination by gas- and liquid-chromatography-Urgent need for harmonisation of analytical methods.

Serum concentrations of lathosterol, the plant sterols campesterol and sitosterol and the cholesterol metabolite 5α-cholestanol are widely used as surrogate markers of cholesterol synthesis and absorption, respectively. Increasing numbers of laboratories utilize a broad spectrum of well-established and recently developed methods for the determination of cholesterol and non-cholesterol sterols (NCS). In order to evaluate the quality of these measurements and to identify possible sources of analytical errors our group initiated the first international survey for cholesterol and NCS. The cholesterol and NCS survey was structured as a two-part survey which took place in the years 2013 and 2014. The first survey part was designed as descriptive, providing information about the variation of reported results from different laboratories. A set of two lyophilized pooled sera (A and B) was sent to twenty laboratories specialized in chromatographic lipid analysis. The different sterols were quantified either by gas chromatography-flame ionization detection, gas chromatography- or liquid chromatography-mass selective detection. The participants were requested to determine cholesterol and NCS concentrations in the provided samples as part of their normal laboratory routine. The second part was designed as interventional survey. Twenty-two laboratories agreed to participate and received again two different lyophilized pooled sera (C and D). In contrast to the first international survey, each participant received standard stock solutions with defined concentrations of cholesterol and NCS. The participants were requested to use diluted calibration solutions from the provided standard stock solutions for quantification of cholesterol and NCS. In both surveys, each laboratory used its own internal standard (5α-cholestane, epicoprostanol or deuterium labelled sterols). Main outcome of the survey was, that unacceptably high interlaboratory variations for cholesterol and NCS concentrations are reported, even when the individual laboratories used the same calibration material. We discuss different sources of errors and recommend all laboratories analysing cholesterol and NCS to participate in regular quality control programs.

Efficacy of repeated phlebotomies in hypertriglyceridemia and iron overload: A prospective, randomized, controlled trial.

BACKGROUND: High ferritin concentration is associated with hypertriglyceridemia, although it is not elucidated if iron overload has a causal role. OBJECTIVE: To evaluate the efficacy of repeated phlebotomies in patients with iron overload and hypertriglyceridemia. METHODS: Twelve weeks, 1:1 randomized, parallel-groups trial conducted at a University Hospital Lipid Clinic, including 86 subjects aged 18-70 years with serum ferritin >300 ng/mL in men or >200 ng/mL in women and triglycerides >200 mg/dL. Participants underwent: (1) three phlebotomies (every 3 weeks) and lipid-lowering dietary counseling or (2) lipid-lowering dietary counseling. The main outcome measured was the mean difference in percent change in triglyceride concentration between groups after the intervention. The mean differences in percent change of other clinical and biochemical variables (including cytokines and proinflammatory markers) after the intervention were also evaluated. RESULTS: Subjects who received phlebotomies showed a significant improvement in iron metabolism. The mean percent change in triglycerides between groups was -4.68 [-20.8, 11.4]%, P = .721. Retinol-binding protein 4 decreased by 9.98 ± 21.7% after phlebotomies, with a mean percent change between groups of -14.2 [-25.8, -2.73]%, P = .017, and correlated to gamma glutamyl transferase, alanine aminotransferase and aspartate aminotransferase change. Subjects with a large reduction in hepcidin showed a large improvement in liver enzymes and proinflammatory markers. CONCLUSIONS: A lipid-lowering diet plus a substantial reduction in iron deposits with repeated phlebotomies in subjects with hyperferritinemia and hypertriglyceridemia did not reduce triglyceride concentration in comparison with a lipid-lowering diet. Iron depletion for lipid management in these patients is not supported.

Cholesterol oversynthesis markers define familial combined hyperlipidemia versus other genetic hypercholesterolemias independently of body weight.

Primary hypercholesterolemia of genetic origin, negative for mutations in LDLR, APOB, PCSK9 and APOE genes (non-FH GH), and familial combined hyperlipidemia (FCHL) are polygenic genetic diseases that occur with hypercholesterolemia, and both share a very high cardiovascular risk. In order to better characterize the metabolic abnormalities associated with these primary hypercholesterolemias, we used noncholesterol sterols, as markers of cholesterol metabolism, to determine their potential differences. Hepatic cholesterol synthesis markers (desmosterol and lanosterol) and intestinal cholesterol absorption markers (sitosterol and campesterol) were determined in non-FH GH (n=200), FCHL (n=100) and genetically defined heterozygous familial hypercholesterolemia subjects (FH) (n=100) and in normolipidemic controls (n=100). FCHL subjects had lower cholesterol absorption and higher cholesterol synthesis than non-FH GH, FH and controls (P<.001). When noncholesterol sterols were adjusted by body mass index (BMI), FCHL subjects had higher cholesterol synthesis than non-FG GH, FH and controls (P<.001). An increase in BMI was accompanied by increased cholesterol synthesis and decreased cholesterol absorption in non-FH GH, FH and controls. However, this association between BMI and cholesterol synthesis was not observed in FCHL. Non-high-density-lipoprotein cholesterol showed a positive correlation with cholesterol synthesis markers similar to that of BMI in non-FH GH, FH and normolipemic controls, but there was no correlation in FCHL. These results suggest that FCHL and non-FH GH have different mechanisms of production. Cholesterol synthesis and absorption are dependent of BMI in non-FH GH, but cholesterol synthesis is increased as a pathogenic mechanism in FCHL independently of age, gender, APOE and BMI.

Single Nucleotide Variants Associated With Polygenic Hypercholesterolemia in Families Diagnosed Clinically With Familial Hypercholesterolemia.

INTRODUCTION AND OBJECTIVES: Approximately 20% to 40% of clinically defined familial hypercholesterolemia cases do not show a causative mutation in candidate genes, and some of them may have a polygenic origin. A cholesterol gene risk score for the diagnosis of polygenic hypercholesterolemia has been demonstrated to be valuable to differentiate polygenic and monogenic hypercholesterolemia. The aim of this study was to determine the contribution to low-density lipoprotein cholesterol (LDL-C) of the single nucleotide variants associated with polygenic hypercholesterolemia in probands with genetic hypercholesterolemia without mutations in candidate genes (nonfamilial hypercholesterolemia genetic hypercholesterolemia) and the genetic score in cascade screening in their family members. METHODS: We recruited 49 nonfamilial hypercholesterolemia genetic hypercholesterolemia families (294 participants) and calculated cholesterol gene scores, derived from single nucleotide variants in SORT1, APOB, ABCG8, APOE and LDLR and lipoprotein(a) plasma concentration. RESULTS: Risk alleles in SORT1, ABCG8, APOE, and LDLR showed a statistically significantly higher frequency in blood relatives than in the 1000 Genomes Project. However, there were no differences between affected and nonaffected members. The contribution of the cholesterol gene score to LDL-C was significantly higher in affected than in nonaffected participants (P = .048). The percentage of the LDL-C variation explained by the score was 3.1%, and this percentage increased to 6.9% in those families with the highest genetic score in the proband. CONCLUSIONS: Nonfamilial hypercholesterolemia genetic hypercholesterolemia families concentrate risk alleles for high LDL-C. Their contribution varies greatly among families, indicating the complexity and heterogeneity of these forms of hypercholesterolemias. The gene score explains a small percentage of LDL-C, which limits its use in diagnosis.

International descriptive and interventional survey for oxycholesterol determination by gas- and liquid-chromatographic methods.

Increasing numbers of laboratories develop new methods based on gas-liquid and high-performance liquid chromatography to determine serum concentrations of oxygenated cholesterol metabolites such as 7α-, 24(S)-, and 27-hydroxycholesterol. We initiated a first international descriptive oxycholesterol (OCS) survey in 2013 and a second interventional survey 2014 in order to compare levels of OCS reported by different laboratories and to define possible sources of analytical errors. In 2013 a set of two lyophilized serum pools (A and B) was sent to nine laboratories in different countries for OCS measurement utilizing their own standard stock solutions. In 2014 eleven laboratories were requested to determine OCS concentrations in lyophilized pooled sera (C and D) utilizing the same provided standard stock solutions of OCS. The participating laboratories submitted results obtained after capillary gas-liquid chromatography-mass selective detection with either epicoprostanol or deuterium labelled sterols as internal standards and high-performance liquid chromatography with mass selective detection and deuterated OCS as internal standard. Each participant received a clear overview of the results in form of Youden-Plots and basic statistical evaluation in its used unit. The coefficients of variation of the concentrations obtained by all laboratories using their individual methods were 58.5-73.3% (survey 1), 56.8-60.3% (survey 2); 36.2-35.8% (survey 1), 56.6-59.8, (survey 2); 61.1-197.7% (survey 1), 47.2-74.2% (survey 2) for 24(S)-, 27-, and 7α-hydroxycholesterol, respectively. We are surprised by the very great differences between the laboratories, even under conditions when the same standards were used. The values of OCS's must be evaluated in relation to the analytical technique used, the efficiency of the ample separation and the nature of the internal standard used. Quantification of the calibration solution and inappropriate internal standards could be identified as major causes for the high variance in the reported results from the different laboratories. A harmonisation of analytical standard methods is highly needed.

Energy-restricted, high-protein diets more effectively impact cardiometabolic profile in overweight and obese women than lower-protein diets.

BACKGROUND & AIMS: High-protein energy-restricted diets have demonstrated efficacy in promoting weight loss in overweight and obesity. However, the protein percentage that achieves optimal efficacy and acceptability remains unknown. We sought to assess the effects of three energy-reduced diets with different percentages of calories from protein (20%, 27%, and 35%) on weight loss and lipids. Secondary outcomes included diet acceptability and compliance. METHODS: Six-month, randomized study included women aged 18-80 years with BMI of 27.5-45 kg/m2 and who were not taking lipid-lowering drugs. We randomly assigned 91 women to one of three calorie-reduced diets with: protein, 20%, 27%, or 35% (80% from animal protein); carbohydrates, 50%, 43%, or 35%; fat, 30%. Dietary intervention involved individual visits with a nutritionist every 2 weeks during the first 3 months. We performed a follow-up visit at 6 months. RESULTS: Eighty women aged 44.0 ± 9.08 years with BMI of 37.7 ± 3.39 kg/m2 completed the study. At 3 months, weight loss was -8.16 ± 4.18 kg, -9.66 ± 5.28 kg, and -10.7 ± 4.28 kg in the 20%, 27%, and 35%-protein groups, respectively (P = 0.16). These figures slightly and homogeneously increased at 6 months. Around 65% of women following 35%-protein diet lost ≥10% of body weight vs. ∼33% in 20%-protein group (P = 0.023). Significant decreases occurred in fat mass, lipids and insulin resistance, especially in the 35%-protein group (P < 0.05 vs. 20% protein). This improvement was not fully explained by weight loss. Triglyceride change was negatively correlated with animal-protein intake. All groups provided similar responses to an acceptance, palatability, and satisfaction questionnaire. CONCLUSIONS: An energy-restricted diet with 35% protein, mostly of animal origin, more effectively impacts cardiometabolic profile than an energy-restricted diet with lower protein content although no clear benefit between diets in terms of overall weight loss was observed. The high-protein diet displayed an excellent safety profile and acceptability. This trial was registered in ClinicalTrials.gov as NCT02160496. CLINICAL TRIAL REGISTRATION: The clinical trial has been registered in ClinicalTrials.gov (Identifier: NCT02160496).

ABCG5/G8 gene is associated with hypercholesterolemias without mutation in candidate genes and noncholesterol sterols.

CONTEXT: Approximately 20% to 40% of clinically defined familial hypercholesterolemia (FH) cases do not show a causative mutation in candidate genes (mutation-negative FH), and some of them may have a polygenic origin. OBJECTIVE: The aim of this work was to study the prevalence of ABCG5/G8 genetic variants in mutation-negative FH, as defects in these genes relate to intestinal hyperabsorption of cholesterol and thus ABCG5/G8 variants could explain in part the mechanism of hypercholesterolemia. DESIGN, SETTING, AND PATIENTS: We sequenced the ABCG5/G8 genes in 214 mutation-negative FH and 97 controls. Surrogate markers of cholesterol absorption (5α-cholestanol, ß-sitosterol, campesterol, stigmasterol, and sitostanol) were quantified by high-performance liquid chromatography-tandem mass spectrometry in both studied groups. RESULTS: We found 8 mutation-negative FH patients (3.73%) with a pathogenic mutation in ABCG5/G8 genes. We observed significantly higher concentration of surrogate markers of cholesterol absorption in mutation-negative FH than in controls. In addition, we found significantly higher concentrations of cholesterol absorption markers in mutation-negative FH with ABCG5/G8 defects than in mutation-negative, ABCG5/G8-negative FH. A gene score reflecting the number of common single nucleotide variants associated with hypercholesterolemia was significantly higher in cases than in controls (P = .032). Subjects with a gene score above the mean had significantly higher 5α-cholestanol and stigmasterol than those with a lower gene score. CONCLUSIONS: Mutation-negative FH subjects accumulate an excess of rare and common gene variations in ABCG5/G8 genes. This variation is associated with increased intestinal absorption of cholesterol, as determined by surrogate makers, suggesting that these loci contribute to hypercholesterolemia by enhancing intestinal cholesterol absorption.

LXR-dependent regulation of macrophage-specific reverse cholesterol transport is impaired in a model of genetic diabesity.

Diabesity and fatty liver have been associated with low levels of high-density lipoprotein cholesterol, and thus could impair macrophage-specific reverse cholesterol transport (m-RCT). Liver X receptor (LXR) plays a critical role in m-RCT. Abcg5/g8 sterol transporters, which are involved in cholesterol trafficking into bile, as well as other LXR targets, could be compromised in the livers of obese individuals. We aimed to determine m-RCT dynamics in a mouse model of diabesity, the db/db mice. These obese mice displayed a significant retention of macrophage-derived cholesterol in the liver and reduced fecal cholesterol elimination compared with nonobese mice. This was associated with a significant downregulation of the hepatic LXR targets, including Abcg5/g8. Pharmacologic induction of LXR promoted the delivery of total tracer output into feces in db/db mice, partly due to increased liver and small intestine Abcg5/Abcg8 gene expression. Notably, a favorable upregulation of the hepatic levels of ABCG5/G8 and NR1H3 was also observed postoperatively in morbidly obese patients, suggesting a similar LXR impairment in these patients. In conclusion, our data show that downregulation of the LXR axis impairs cholesterol transfer from macrophages to feces in db/db mice, whereas the induction of the LXR axis partly restores impaired m-RCT by elevating the liver and small intestine expressions of Abcg5/g8.