Familial dyslipidaemias: an overview of genetics, pathophysiology and management

Lipid-Lowering Effects of Carob Extracts (Ceratonia siliqua): Proposed Mechanisms and Clinical Importance

The global prevalence of dyslipidemia (elevated plasma levels of total cholesterol, LDL-Cholesterol, triglycerides, and lower plasma levels of HDL-Cholesterol) is constantly on the rise. Lately, carob pulp has been recognized as an effective natural product for the treatment of dyslipidemia. The two main components of the carob pulp, polyphenols, and insoluble fiber are believed to have beneficial effects on lipid metabolism. Studies on humans and animals confirmed its lipid-lowering effects. Several mechanisms have been proposed to explain this phenomenon, namely by affecting three organ systems: 1) gastrointestinal tract, 2) liver and 3) adipose tissue. Also, carob products have antioxidative, anti-inflammatory, and vascular-protective activity.

Translating genetic association of lipid levels for biological and clinical application

PURPOSE OF REVIEW

This review focuses on the foundational evidence from the last two decades of lipid genetics research and describes the current status of data-driven approaches for transethnic GWAS, fine-mapping, transcriptome informed fine-mapping, and disease prediction.

RECENT FINDINGS

Current lipid genetics research aims to understand the association mechanisms and clinical relevance of lipid loci as well as to capture population specific associations found in global ancestries. Recent genome-wide trans-ethnic association meta-analyses have identified 118 novel lipid loci reaching genome-wide significance. Gene-based burden tests of whole exome sequencing data have identified three genes-PCSK9, LDLR, and APOB-with significant rare variant burden associated with familial dyslipidemia. Transcriptome-wide association studies discovered five previously unreported lipid-associated loci. Additionally, the predictive power of genome-wide genetic risk scores amalgamating the polygenic determinants of lipid levels can potentially be used to increase the accuracy of coronary artery disease prediction.

CONCLUSIONS

Lipids are one of the most successful group of traits in the era of genome-wide genetic discovery for identification of novel loci and plausible drug targets. However, a substantial fraction of lipid trait heritability remains unexplained. Further analysis of diverse ancestries and state of the art methods for association locus refinement could potentially reveal some of this missing heritability and increase the clinical application of the genomic association results.

The modulatory role of prime identified compounds in the bioactive fraction of Homalium zeylanicum in high-fat diet fed-streptozotocin-induced type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Homalium zeylanicum (Gardner) Benth. is a medicinal plant traditionally used in controlling diabetes which thus far has been assessed by the authors only to a very limited extent.

PURPOSE

To fill the research gap in the literature review, we investigated the antihyperglycemic effects of hydro alcohol fraction of bark of H. zeylanicum (HAHZB) by modulating oxidative stress and inflammation in high-fat diet fed-streptozotocin (HFD/STZ)-induced type-2 diabetic rats.

MATERIALS AND METHODS

To understand the antioxidant capacity of HAHZB, oxygen radical absorbance capacity (ORAC) and cell-based antioxidant protection in erythrocytes (CAP-e) were performed. GC-MS/MS analysis was performed to assess the bioactive components in HAHZB. HFD/STZ-induced diabetic rats were treated orally with HAHZB (300 and 400 mg/kg) for 28 days. After the end of the experiment, marker profiling and histopathological observation of blood and pancreas were examined. The study also highlights interaction between diabetes, oxidative stress and inflammation by examining the increased pro-inflammatory cytokines e.g. TNF-α and C-reactive protein (CRP) promotes DNA damage e.g. oxidation of 8-hydroxy-2-deoxyguanosine (8-OHdG) in chronic hyperglycaemia.

RESULTS

In ex vivo cellular antioxidant capacity of -CAP-e and ORAC assays, HAHZB showed remarkable free radical scavenging ability in a dose dependent manner. GC-MS/MS analysis identified 28 no. of compounds and out of which, oleic acid (1.03%), ethyl tridecanoate (11.77%), phytol (1.29), 9,12-octadecadienoic acid, methyl ester, (E,E)-(5.97%), stigmasterol (1.30%) and β-sitosterol (2.86%) have antioxidant, anti-inflammatory and anti-diabetic activities. HAHZB 400 mg/kg significantly (p < 0.001) improved the lipid profile (TC: 74.66 ± 0.59, HDL-C: 22.08 ± 0.46, LDL-C: 38.06 ± 0.69, and TG: 171.92 ± 1.01 mg/dL) as well as restoring antidiabetic markers (SG: 209.62 ± 1.05 mg/dL, SI: 15.07 ± 0.11 μIU/mL, HOMA-IR: 7.79 ± 0.04 %, and HbA1C: 8.93 ± 0.03 %) and renal functional markers (Tg: 291.26 ± 0.57 pg/mL, BUN: 23.79 ± 0.14 mg/dL, and Cr: 1.34 ± 0.04 mg/dL) in diabetic rats. Oxidative stress markers of pancreas (MDA: 3.65 ± 0.17 nM TBARS /mg protein, SOD: 3.14 ± 0.28 U/mg protein, CAT: 7.88 ± 0.23 U/mg protein, GSH: 12.63 ± 0.28 µM/g of tissue) were restored to normal as evidenced by histological architecture of pancreatic islet cells. The increased level of pro-inflammatory cytokines and oxidative DNA damage were significantly restored (TNF-α: 54.48 ± 3.19 pg/mL, CRP: 440.22 ± 7.86 ng/mL, and 8-OHdG: 63.65 ± 1.84 ng/mL) by HAHZB in diabetic rats.

CONCLUSION

The present findings confirm that the presence of bioactive compounds in HAHZB exert therapeutic protective effect by decreasing oxidative, inflammation and pancreatic β-cell damage in oxidative stress induced diabetic rats.

Investigating the Atherogenic Risk of Lipoprotein(a) in Type 2 Diabetic Patients

Type 2 diabetes mellitus (T2DM) has high morbidity and results in increased risk of mortality mainly due to cardiovascular diseases. Different factors have been found to be responsible for the increased prevalence of coronary artery disease (CAD) in T2DM. One of these factors includes raised serum levels of lipoprotein(a) (Lp(a)). The present study was designed to evaluate the association of Lp(a) levels with T2DM in Libyan patients and find the degree of association between Lp(a), glycemic control, insulin, and lipid profile. The study included 100 T2DM patients, recruited from the Benghazi Center for Diagnosis and Treatment of Diabetes, and 30 apparently healthy age and sex-matched individuals, to serve as controls. All participants completed a questionnaire to obtain clinical information and medical history. Blood samples were collected and analyzed for Lp(a), fasting blood glucose (FBS), HbA1c, insulin, total cholesterol (TC), triglycerides (TAG), low-density lipoprotein c (LDL-c), and high-density lipoprotein c (HDL-c). The results from the comparison between the control and experimental groups showed that Lp(a) was significantly higher in diabetic patients. It showed the positive correlation with TC and LDL-c. On the contrary, it showed no significant correlations with glycemic control parameters nor insulin, TAG, HDL-c, body mass index (BMI), and blood pressor (BP). Cardiovascular disease (CVD) risk in type 2 diabetic patients could be dependent on risk factors other than LDL-c, which may not be an independent risk factor for the development and progression of atherogenesis in T2DM. Lp(a) may be a new metabolic syndrome risk factor, and it may be useful as a cardiovascular risk biomarker in future clinical practice.

Cardiovascular Disease Risk Factors Profile in Individuals With Diabetes Compared With Non-Diabetic Subjects in North-East of Iran

Background

Diabetes mellitus is assumed to be a strong risk factor for cardiovascular diseases (CVD) and is frequently associated with other CVD risk factors.

Objectives

The aims of this study were to assess the prevalence of different patterns of dyslipidemia in individuals with diabetes compared with non-diabetic subjects and evaluate other accompanied CVD risk factors between the two groups.

Patients and Methods

This was an analytical cross-sectional study on 230 participants, aged 28 - 66 years old, who were referred to different urban health centers of Khorasan Razavi province (north-east of Iran). Data from the participants were collected during their first visit by primary care physicians. Statistical package for social science (version 11.5) was used to analyze the data. The chi-square or Fisher’s exact, student’s t or the Mann-Whitney U and correlation tests were used in the analysis.

Results

The age and gender of the participants were not different between the two groups (P = 0.1 and P = 0.4, respectively). The most common patterns of dyslipidemia in both groups were isolated dyslipidemia followed by combined dyslipidemia. Prevalence of dyslipidemia as a whole (one, two or three lipid profile abnormalities) in patients with diabetes and non-diabetic participants was 89.3% and 82.6%, respectively and the difference between the two groups was not statistically significant (P = 0.1). Subjects with diabetes had higher systolic blood pressure (P < 0.001), higher diastolic blood pressure (P = 0.002) and higher body mass index (P = 0.09) compared to non-diabetics. Moreover, they were more likely to have higher levels of total cholesterol (P = 0.01), triglycerides (P = 0.001) and low density lipoprotein cholesterol (P = 0.009) and lower levels of high density lipoprotein cholesterol (P = 0.2).

Conclusions

Cardiovascular diseases risk factors are more common in patients with diabetes; however, non-diabetic individuals also had a high prevalence of risk factors in our region, predisposing them to diabetes. Therefore, further attention by the medical community is necessary to choose effective strategies for a more a aggressive approach to prevent and manage these risk factors.

Persistent lipid abnormalities in statin-treated coronary artery disease patients with and without diabetes in China

BACKGROUND

We evaluate the prevalence of persistent lipid abnormalities and statin use in Chinese coronary artery disease patients with and without diabetes.

METHODS AND RESULTS

In this cross-sectional observational study, 8965 outpatients from 200 clinical departments of 122 hospitals in 27 provinces nationwide of China who had coronary artery disease and were taking a statin were consecutively enrolled and divided into two groups based on diabetes status. The European Society of Cardiology/European Arthrosclerosis Society Guidelines for the management of dyslipidemias and the Chinese Guidelines on Prevention and Treatment of Dyslipidemia in Adults were used to compare the control rates of low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, and triglycerides (TG). Among the 8965 participants, 33.3% had been diagnosed with diabetes mellitus. According to the ESC Guidelines, the percentage of patients with not at goal LDL cholesterol did not differ significantly between patients with diabetes and those without diabetes (71.9% vs. 72.7%, P=0.46). The percentages of patients with not-at-goal levels of HDL and TG were 42.9% vs. 34.4% (P<0.001) and 39.1% vs. 34.3% (P<0.001) among patients with diabetes and those without, respectively. Only approximately 10% of patients in both groups had optimal LDL-C, HDL-C, and TG levels. Compared with patients without diabetes, patients with diabetes were more likely to have mixed dyslipidemia. Atorvastatin (47.0%) and simvastatin (34.4%) were the two most frequently used statins, and the average statin dosage was 29.09mg/day (simvastatin equivalent). Less than 1% of patients were treated with another lipid-lowering drug in combination with a statin.

CONCLUSIONS

Although international guidelines highly recommend intensive lipid modulation in patients with coronary artery disease, persistent dyslipidemia is still prevalent among these patients in China, even with statin treatment.

The safety and anti-hypercholesterolemic effect of coptisine in Syrian golden hamsters

Current work was conducted to evaluate the cholesterol-lowering effect of coptisine extracted from Rhizoma coptidis in Syrian golden hamsters. The safety results indicated that coptisine was a safe and low-toxic compound. Coptisine showed a beneficial effect in the abnormal serum lipid levels induced by a high-fat and high-cholesterol diet (HFHC): at a concentration of 70.05 mg/kg, coptisine significantly led to a decrease in total cholesterol, triglycerides, and low-density lipoprotein cholesterol (LDL-c) levels by 26.70, 15.38, and 22.22 %, respectively, and high-density lipoprotein cholesterol (HDL-c) was increased by 41.74 % in serum of hamsters (p < 0.01). In addition, total bile acid (TBA) levels in feces of hamsters were elevated after coptisine administration. Further investigation has suggested that the mRNA and protein expression of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) in the liver of hamsters was down-regulated by high-dosage coptisine treatment (p < 0.05); mRNA and protein expression of low-density lipoprotein receptor (LDLR) and cholesterol 7α-hydroxylase (CYP7A1) were dramatically up-regulated by coptisine administration. The apical sodium-dependent bile salt transporter expression was down-regulated in the coptisine-treated animals, but showed no significant differences from the HFHC groups. Taken together, our results demonstrate that a high dosage of coptisine could inhibit cholesterol synthesis via suppressing the HMGCR expression and promoting the use and excretion of cholesterol via up-regulating LDLR and CYP7A1 expression. These findings suggest a critical role for coptisine in anti- hypercholesterolemia, and thus it needs to be considered as a potential natural cholesterol lowering agent.

Lipid profile abnormalities seen in T2DM patients in primary healthcare in Turkey: a cross-sectional study

BACKGROUND

Diabetes is characterized by chronic hyperglycemia and disturbances of carbohydrate, lipid and protein metabolism. We aimed to research association between serum lipid profile and blood glucose, hypothesizing that early detection and treatment of lipid abnormalities can minimize the risk for atherogenic cardiovascular disorder and cerebrovascular accident in patients with type 2 diabetes mellitus.

METHODS

Fasting blood glucose (FBG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), triglyceride (TG) and glycated haemoglobin (HbA1c) levels were evaluated. A hepatic ultrasound was performed for every diabetic to evaluate hepatosteatosis. The study was done from January 2014 to June 2014 among 132 patients with T2DM who were admitted to outpatient clinic of Family Medicine department in a university hospital. The patients whose taking multi-vitamin supplementation or having hepatic, renal or metabolic bone disorders (including parathyroid related problems) were excluded from the study for the reason that those conditions might affect the carbohydrate and lipid metabolism in diabetes. Test of significance was calculated by unpaired student's t test between cases and controls. Correlation studies (Pearson's correlation) were performed between the variables of blood glucose and serum lipid profile. Significance was set at p<0.05.

RESULTS

Results of serum lipid profile showed that the mean values for TC, TG, HDL and LDL in female patients were 227.6 ± 57.7 mg/dl, 221.6 ± 101.1 mg/dl, 31.5 ± 6.7 mg/dl and 136.5 ± 43.7 mg/dl, respectively. The mean values for TC, TG, HDL and LDL in male patients were 219.1 ± 34.7 mg/dl, 250.0 ± 100.7 mg/dl, 30.2 ± 7.4 mg/dl and 125.7 ± 21.4 mg/dl, respectively. Significantly higher mean serum levels of TC, TG and LDL and significantly lower mean serum levels of HDL were noted in patients with diabetes (p<0.001). FBG showed significant positive correlation with TC (p<0.05) and TG (p<0.05). Significant correlations were observed between serum levels of TC, TG, LDL and hepatosteatosis and HbA1c (p<0.05).

CONCLUSIONS

The study showed widespread lipid abnormalities in the course of diabetes triggered dyslipidemia as hypercholesterolemia, hypertriglyceridemia, elevated LDL and decreased HDL. This study proposes the predominance of hyperlipidemia over increased prevalence of diabetic dyslipidemia.

Induction of apolipoprotein A-I gene expression by black seed (Nigella sativa) extracts

CONTEXT

Black seed [Nigella sativa L. (Ranunculaceae)] has been shown in animal models to lower serum cholesterol levels.

OBJECTIVES

In order to determine if extracts from black seed have any effects on high-density lipoprotein (HDL), we characterized the effects of black seed extract on apolipoprotein A-I (apo A-I) gene expression, the primary protein component of HDL.

MATERIALS AND METHODS

Hepatocytes (HepG2) and intestinal cells (Caco-2) were treated with black seed extracts, and Apo A-I, peroxisome proliferator-activated receptor α (PPARα), and retinoid-x-receptor α (RXRα) were measured by Western blot analysis. Apo A-I mRNA levels were measured by quantitative real-time polymerase chain reaction and apo A-I gene transcription was measured by transient transfection of apo A-I reporter plasmids.

RESULTS

Extracts from black seeds significantly increased hepatic and intestinal apo A-I secretion, as well as apo A-I mRNA and gene promoter activity. This effect required a PPARα binding site in the apo A-I gene promoter. Treatment of the extract with either heat or trypsin had no effect on its ability to induce apo A-I secretion. Treatment with black seed extract induced PPARα expression 9-fold and RXRα expression 2.5-fold. Furthermore, the addition of PPARα siRNA but not a control siRNA prevented some but not all the positive effects of black seed on apo A-I secretion.

DISCUSSION

Black seed extract is a potent inducer of apo A-I gene expression, presumably by enhancing PPARα/RXRα expression.

CONCLUSIONS

We conclude that black seed may have beneficial effects in treating dyslipidemia and coronary heart disease.

The effect of nutritional supplements on serum high-density lipoprotein cholesterol and apolipoprotein A-I

One of the factors contributing to the increased risk of developing premature atherosclerosis is low plasma concentrations of high-density lipoprotein (HDL) cholesterol. Multiple potential mechanisms account for the cardioprotective effects of HDL and its main protein apolipoprotein A-I (apo A-I). Diet has an important role in modulating HDL cholesterol level. The widespread use of nutritional supplements may also alter the biology of HDL. In this review, we discuss the effect of select nutritional supplements on serum HDL cholesterol and apo A-I levels. Some nutritional supplements, such as phytosterols, soy proteins, and black seed extracts, may increase HDL cholesterol levels, while others such as cholic acid and high doses of commonly used antioxidant vitamins may downregulate HDL cholesterol levels and reduce its cardioprotection. Multiple mechanisms are involved in the regulation of HDL levels, so changes in production and clearance of HDL may have different clinical implications. The clinical relevance of the changes in HDL and apo A-I caused by nutrient supplementation needs to be tested in controlled clinical trials.

The prevalence of dyslipidemia in patients with diabetes mellitus of ayurveda Hospital

Background

Dyslipidemia is one of the major risk factors for cardiovascular disease in diabetes mellitus. Early detection and treatment of dyslipidemia in type-2 diabetes mellitus can prevent risk for atherogenic cardiovascular disorder. The rationale of this study was to detect the lipid abnormality in diabetic patients.

Methods

Necessary data was collected from the medical archives of 150 patients (73 female and 77 male) with diabetes mellitus registered in Department of pathology and biochemistry of a Ayurveda hospital established at Kolkata, India.

Results

The mean ages of female and male subjects were 51.8 ± 10.8 and 53.2 ± 11.3 years respectively. The range and mean value of FBS in females were 113–342 mg/dl and 157.7 ± 6.3 mg/dl, while the range and mean value of PPBS in females were 135–560 mg/dl and 275.5 ± 12.3 mg/dl respectively. Results showed that range and mean value of FBS in males were 111–462 mg/dl and 160.8 ± 7.4 mg/dl, while the range and mean value of PPBS in males were 136–598 mg/dl and 302.1 ± 12.6 mg/dl respectively. Results of serum lipids showed that the mean values for total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and very low density lipoprotein cholesterol (VLDL-C) in female patients were 202.2 ± 5.9 mg/dl, 168.3 ± 8.2 mg/dl, 44.9 ± 1.3 mg/dl, 123.6 ± 5.2 mg/dl and 33.7 ± 1.7 mg/dl respectively. The mean values for TC, TG, HDL-C, LDL-C and VLDL-C in male patients were 182.5 ± 4.8 mg/dl, 128.1 ± 10.8 mg/dl, 40.8 ± 1.2 mg/dl, 105.4 ± 4.8 mg/dl and 36.2 ± 2.2 respectively. FBS showed significant positive correlation with PPBS, cholesterol, TG, and VLDL-C. PPBS also demonstrated direct and significant correlations with TG and VLDL-C.

Conclusions

The study showed common lipid abnormalities during diabetes induced dyslipidemia i.e., hypercholesterolemia, hypertriglyceridemia and elevated LDL-C. This study suggests the dominance of hyperlipidemia over increased prevalence of dyslipidemia.

CD36 haplotypes are associated with lipid profile in normal-weight subjects

Background

Dyslipidemia is a common metabolic disorder that may result from abnormalities in the synthesis, processing and catabolism of lipoprotein particles. Disorders of lipoprotein concentrations and elevated concentration of oxidized lipoproteins (oxLDL) are risk factors in the pathogenesis of cardiovascular diseases (CVD). CD36 plays an important role in lipid metabolism and polymorphisms in the CD36 gene are related to cardiovascular risk factors. The purpose of this study was to evaluate whether there is an association between genotypes and haplotypes of five polymorphisms in the CD36 gene with lipid levels in young normal-weight subjects.

Methods

A total of 232 unrelated subjects with normal-weight of 18 to 25 years old (157 women and 75 men) were randomly selected. The lipid profile and glucose levels were measured by enzymatic colorimetric assays. Genotyping of the polymorphisms -33137A/G (rs1984112), -31118G/A (rs1761667), -22674 T/C (rs2151916), 27645 Ins/Del (rs3840546) and 30294G/C (rs1049673) in the CD36 receptor gene was performed by polymerase chain reaction and restriction fragment length polymorphism, linkage disequilibrium analysis among the five polymorphisms and an analysis of haplotype were estimated.

Results

HDL-C levels was lower in men than in women (P = 0.03). However, the median oxLDL levels in men was higher than in women (P = 0.05). There was no significant difference in the levels of TC, TG, LDL-C and glucose (P > 0.05). HDL-C levels were lower in the subjects with TC genotype of polymorphism -22674 T/C (P = 0.04), but the carriers of TT genotype had lower oxLDL levels (P = 0.01). LDL-C levels were higher in young carriers of CC genotype for 30294G/C polymorphism than non-carriers (P = 0.03). The subjects carrying the AATDC haplotype had 3.2 times presumably higher risk of LDL-C > 100 mg/dL than the carrying the AGTIG haplotype (P = 0.02), whereas the subjects carrying the AATIC haplotype had 2.0 times presumably higher risk of TC > 200 mg/dL than the carrying the AGTIC haplotype (P = 0.02).

Conclusion

The study provides evidence of a genetic association of CD36 haplotypes with the variability in LDL-C and TC levels in a sample of normal-weight subjects.

Pattern and predictors of dyslipidemia in patients with type 2 diabetes mellitus

Dyslipidemia is a major risk factor for macro-vascular complications in patients with type 2 diabetes mellitus (T2DM). Present study explored pattern and predictors of dyslipidemia in Bangladeshi T2DM patients. The cross-sectional study is conducted among 366 consecutive eligible T2DM patients aged >30 years, BIRDEM diabetic hospital, during July-to-December 2010. Physical examination, diabetic profile, lipid profile and serum createnine was performed. Adjusted odds ratio and confidence limit were generated through binary logistic regression. Most frequent form (59.3%) of dyslipidemia is low HDL. Duration of T2DM is significantly correlated with TC (P<0.05), HDL (P<0.05) and LDL (P<0.05) in both male and female. Glycemic control in terms of HbA1c >7% appeared as predictor of dyslipidemia (P<0.01). Duration T2DM is associated with increased risk of having higher TC (P<0.05), LDL (P<0.05) and lower HDL (P<0.01) and does not seem to affect triglyceride (P>0.05). T2DM with comorbid hypertension seems to predict hyper tri-glyceridemia and lower HDL. Both TC-HDL ratio and LDL-HDL ratio appeared as good predictor of all four parameters of dyslipidemia (P<0.01). The characteristic features of diabetic dyslipidemia are low HDL, high triglyceride and LDL cholesterol level. Low HDL level is the most frequent type of abnormality. Poor glycemic control, prolonged duration, coexisting hypertension predicts dyslipidemia in T2DM.

Impact of variants within seven candidate genes on statin treatment efficacy

Statins are the most commonly used drugs in patients with dyslipidemia. Among the patients, a significant inter-individual variability with supposed strong genetic background in statin treatment efficacy has been observed. Genome wide screenings detected variants within the CELSR2/PSRC1/SORT1, CILP2/PBX4, APOB, APOE/C1/C4, HMGCoA reductase, LDL receptor and PCSK9 genes that are among the candidates potentially modifying response to statins. Ten variants (SNPs) within these genes (rs599838, rs646776, rs16996148, rs693, rs515135, rs4420638, rs12654264, rs6511720, rs6235, rs11206510) were analyzed in 895 (46 % men, average age 60.3+/-13.1 years) patients with dyslipidemia treated with equipotent doses of statins (~90 % on simvastatin or atorvastatin, doses 10 or 20 mg) and selected 672 normolipidemic controls (40 % men, average age 46.5 years). Lipid parameters were available prior to the treatment and after 12 weeks of therapy. Statin treatment resulted in a significant decrease of both total cholesterol (7.00+/-1.53-->5.15+/-1.17 mmol/l, P<0.0001) and triglycerides (2.03+/-1.01-->1.65+/-1.23 mmol/l, P<0.0005). Rs599838 variant was not detected in first analyzed 284 patients. After adjustment for multiple testing, there was no significant association between individual SNPs and statin treatment efficacy. Only the rs4420638 (APOE/C1/C4 gene cluster) G allele carriers seem to show more profitable change of HDL cholesterol (P=0.007 without and P=0.06 after adjustment). Results demonstrated that, although associated with plasma TC and LDL cholesterol per se, variants within the CELSR2/PSRC1/SORT1, CILP2/PBX4, APOB, APOE/C1/C4, HMGCoA reductase, LDL receptor and PCSK9 genes do not modify therapeutic response to statins.

Beneficial effects of swertiamarin on dyslipidaemia in streptozotocin-induced type 2 diabetic rats

Dyslipidaemia is one of the major risk factors for cardiovascular disease in diabetes mellitus. Lipid changes associated with diabetes mellitus are attributed to increases in free fatty acid flux, secondary to insulin resistance. In the present study, we have investigated the beneficial effects of swertiamarin on dyslipidaemic conditions associated with type 2 diabetes in streptozotocin-induced type 2 diabetic rats. Swertiamarin (50 mg/kg, i.p.) administered once a day for 6 weeks resulted in significant (p < 0.001) reductions in serum triglycerides, cholesterol and low-density lipoprotein levels in diabetic animals as compared with diabetic control animals. Serum fasting glucose was significantly (p < 0.05) decreased, moreover, the insulin sensitivity index was significantly (p < 0.05) increased in swertiamarin treated animals. Overall the data suggest that swertiamarin has beneficial effects on diabetic associated complications such as dyslipidaemia.

Endogenous and diet-induced hypercholesterolemia in nonhuman primates: effects of age, adiposity, and diabetes on lipoprotein profiles

Nonhuman primates (NHPs) share with humans many features of lipid metabolism and often develop all features of the metabolic syndrome, including hypertriglyceridemia and low high-density lipoprotein cholesterol, and have been used in many studies of potential therapeutics during the preclinical phase. Here we identify for the first time in middle-aged and older rhesus the natural occurrence of hypercholesterolemia, and this hypercholesterolemia develops despite maintenance on a low-cholesterol diet. The aims of this study were to (a) define normal and hypercholesterolemia in rhesus monkeys, (b) determine the factors associated with the development of hypercholesterolemia, (c) compare the lipoprotein profiles in adult rhesus monkeys fed a low-fat/low-cholesterol diet (LFLC) with the profiles of human subjects, and (d) determine the effect of a 16-week high-fat/high-cholesterol (HFHC) diet feeding on total cholesterol and lipoprotein profiles in middle-aged and older monkeys. In our colony, maintained on a constant diet with negligible cholesterol, the mean total cholesterol level in healthy nondiabetic monkeys was 3.7 ± 0.02 mmol/L, with hypercholesterolemia identified as the 95th percentile of the normal cholesterol distribution (≥5.2 mmol/L). Severe hypercholesterolemia developed in the HFHC-fed group; however, despite the high-fat diet composition, unexpectedly, no weight gain occurred in these NHPs. The diet-induced hypercholesterolemia differed significantly in lipoprotein pattern from that of the spontaneous hypercholesterolemia. In summary, despite ingesting only a LFLC, NHPs frequently develop hypercholesterolemia, reflecting lipoprotein patterns similar to human subjects; and this lipid profile of spontaneous hypercholesterolemia differs significantly from the hypercholesterolemia induced by an HFHC diet.

Effects of lipid-lowering drugs on reverse cholesterol transport gene expressions in peripheral blood mononuclear and HepG2 cells

AIMS

The ATP-binding cassette transporters, ABCA1 and ABCG1, are LXR-target genes that play an important role in reverse cholesterol transport. We examined the effects of inhibitors of the cholesterol absorption (ezetimibe) and synthesis (statins) on expression of these transporters in HepG2 cells and peripheral blood mononuclear cells (PBMCs) of individuals with primary (and nonfamilial) hypercholesterolemia (HC).

MATERIALS & METHODS

A total of 48 HC individuals were treated with atorvastatin (10 mg/day/4 weeks) and 23 were treated with ezetimibe (10 mg/day/4 weeks), followed by simvastatin (10 mg/day/8 weeks) and simvastatin plus ezetimibe (10 mg of each/day/4 weeks). Gene expression was examined in statin- or ezetimibe-treated and control HepG2 cells as well as PBMCs using real-time PCR.

RESULTS

In PBMCs, statins and ezetimibe downregulated ABCA1 and ABCG1 mRNA expression but did not modulate NR1H2 (LXR-β) and NR1H3 (LXR-α) levels. Positive correlations of ABCA1 with ABCG1 and of NR1H2 with NR1H3 expressions were found in all phases of the treatments. In HepG2 cells, ABCA1 mRNA levels remained unaltered while ABCG1 expression was increased by statin (1.0-10.0 µM) or ezetimibe (5.0 µM) treatments. Atorvastatin upregulated NR1H2 and NR1H3 only at 10.0 µM, meanwhile ezetimibe (1.0-5.0 µM) downregulated NR1H2 but did not change NR1H3 expression.

CONCLUSION

Our findings reveal that lipid-lowering drugs downregulate ABCA1 and ABCG1 mRNA expression in PBMCs of HC individuals and exhibit differential effects on HepG2 cells. Moreover, they indicate that the ABCA1 and ABCG1 transcript levels were not correlated directly to LXR mRNA expression in both cell models treated with lipid-lowering drugs.

A role for PPARα in the regulation of arginine metabolism and nitric oxide synthesis

The pleiotropic effects of PPARα may include the regulation of amino acid metabolism. Nitric oxide (NO) is a key player in vascular homeostasis. NO synthesis may be jeopardized by a differential channeling of arginine toward urea (via arginase) versus NO (via NO synthase, NOS). This was studied in wild-type (WT) and PPARα-null (KO) mice fed diets containing either saturated fatty acids (COCO diet) or 18:3 n-3 (LIN diet). Metabolic markers of arginine metabolism were assayed in urine and plasma. mRNA levels of arginases and NOS were determined in liver. Whole-body NO synthesis and the conversion of systemic arginine into urea were assessed by using (15)N(2)-guanido-arginine and measuring urinary (15)NO(3) and [(15)N]-urea. PPARα deficiency resulted in a markedly lower whole-body NO synthesis, whereas the conversion of systemic arginine into urea remained unaffected. PPARα deficiency also increased plasma arginine and decreased citrulline concentration in plasma. These changes could not be ascribed to a direct effect on hepatic target genes, since NOS mRNA levels were unaffected, and arginase mRNA levels decreased in KO mice. Despite the low level in the diet, the nature of the fatty acids modulated some effects of PPARα deficiency, including plasma arginine and urea, which increased more in KO mice fed the LIN diet than in those fed the COCO diet. In conclusion, PPARα is largely involved in normal whole-body NO synthesis. This warrants further study on the potential of PPARα activation to maintain NO synthesis in the initiation of the metabolic syndrome.

Dyslipidemia in type 2 diabetes mellitus

Dyslipidemia is one of the major risk factors for cardiovascular disease in diabetes mellitus. The characteristic features of diabetic dyslipidemia are a high plasma triglyceride concentration, low HDL cholesterol concentration and increased concentration of small dense LDL-cholesterol particles. The lipid changes associated with diabetes mellitus are attributed to increased free fatty acid flux secondary to insulin resistance. The availability of multiple lipid-lowering drugs and supplements provides new opportunities for patients to achieve target lipid levels. However, the variety of therapeutic options poses a challenge in the prioritization of drug therapy. The prevalence of hypercholesterolemia is not increased in patients with diabetes mellitus, but mortality from coronary heart disease increases exponentially as a function of serum cholesterol levels, and lowering of cholesterol with statins reduces diabetic patients' relative cardiovascular risk. Although drug therapy for dyslipidemia must be individualized, most people with diabetes mellitus are candidates for statin therapy, and often need treatment with multiple agents to achieve therapeutic goals.

Obesity-related changes in high-density lipoprotein metabolism

Obesity is associated with a 3-or-more-fold increase in the risk of fatal and nonfatal myocardial infarction (1,2,3,4,5,6). The American Heart Association has reclassified obesity as a major, modifiable risk factor for coronary heart disease (7). The increased prevalence of premature coronary heart disease in obesity is attributed to multiple factors (8,9,10). A principal contributor to this serious morbidity is the alterations in plasma lipid and lipoprotein levels. The dyslipidemia of obesity is commonly manifested as high plasma triglyceride levels, low high-density lipoprotein cholesterol (HDLc), and normal low-density lipoprotein cholesterol (LDLc) with preponderance of small dense LDL particles (7,8,9,10). However, there is a considerable heterogeneity of plasma lipid profile in overweight and obese people. The precise cause of this heterogeneity is not entirely clear but has been partly attributed to the degree of visceral adiposity and insulin resistance. The emergence of glucose intolerance or a genetic predisposition to familial combined hyperlipidemia will further modify the plasma lipid phenotype in obese people (11,12,13,14,15).

Ezetimibe: cholesterol lowering and beyond

Ezetimibe is a cholesterol absorption inhibitor that blocks the intestinal absorption of both biliary and dietary cholesterol. It appears to exert its effect by blocking intestinal sterol transporters, specifically Niemann-Pick C1-like 1 proteins, thereby inhibiting the intestinal absorption of cholesterol, phytosterols and certain oxysterols. Ezetimibe monotherapy and in combination with statin therapy is primarily indicated for lowering LDL-cholesterol levels. In addition, it may favorably affect other parameters that could potentially further reduce atherosclerotic coronary heart disease risk, such as raising HDL-cholesterol and lowering levels of triglycerides, non-HDL-cholesterol, apolipoprotein B and remnant-like particle cholesterol. Further effects of ezetimibe include a reduction in circulating phytosterols and oxysterols and, when used in combination with statins, a reduction in high-sensitivity C-reactive protein. The clinical significance of the LDL-cholesterol lowering and other effects of ezetimibe is being evaluated in clinical outcome studies.

The genetic architecture of fasting plasma triglyceride response to fenofibrate treatment

Metabolic response to the triglyceride (TG)-lowering drug, fenofibrate, is shaped by interactions between genetic and environmental factors, yet knowledge regarding the genetic determinants of this response is primarily limited to single-gene effects. Since very low-density lipoprotein (VLDL) is the central carrier of fasting TG, identifying factors that affect both total TG and VLDL-TG response to fenofibrate is critical for predicting individual fenofibrate response. As part of the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study, 688 individuals from 161 families were genotyped for 91 single-nucleotide polymorphisms (SNPs) in 25 genes known to be involved in lipoprotein metabolism. Using generalized estimating equations to control for family structure, we performed linear modeling to investigate whether single SNPs, single covariates, SNP-SNP interactions, and/or SNP-covariate interactions had a significant association with the change in total fasting TG and fasting VLDL-TG after 3 weeks of fenofibrate treatment. A 10-iteration fourfold cross-validation procedure was used to validate significant associations and quantify their predictive abilities. More than one-third of the significant, cross-validated SNP-SNP interactions predicting each outcome involved just five SNPs, showing that these SNPs are of key importance to fenofibrate response. Multiple variable models constructed using the top-ranked SNP--covariate interactions explained 11.9% more variation in the change in TG and 7.8% more variation in the change in VLDL than baseline TG alone. These results yield insight into the complex biology of fenofibrate response, which can be used to target fenofibrate therapy to individuals who are most likely to benefit from the drug.