Role of Insulin Resistance in Familial Combined Hyperlipidemia

Lipoprotein(a), metabolic profile and new-onset type 2 diabetes in patients with familial combined hyperlipidemia: A 9 year follow-up study

BACKGROUND

Lipoprotein(a) [Lp(a)] appears to have an inverse association with the risk of type 2 diabetes mellitus in the general population.

OBJECTIVE

This study aimed to investigate the prognostic role of Lp(a) regarding the development of type 2 diabetes in the special population of subjects with familial combined hyperlipidemia (FCH).

METHODS

This cohort study included 474 patients (mean age 49.7±11.3 years, 64% males) with FCH, without diabetes at baseline who were followed for a mean period of 8.2±6.8 years. At baseline evaluation venous blood samples were obtained for the determination of lipid profile and Lp(a) levels. The endpoint of interest was the development of diabetes.

RESULTS

Patients with increased Lp(a) levels ≥30 mg/dl compared to those with low Lp(a) levels <30 mg/dl had lower levels of triglycerides (238±113 vs 268±129 mg/dl, p = 0.01), greater levels of high-density lipoprotein (HDL) cholesterol (44±10 vs 41±10 mg/dl, p = 0.01) and hypertension in a greater percentage (42% vs 32%, p = 0.03). The incidence of new-onset diabetes during the follow-up period was 10.1% (n = 48). Multiple Cox regression analysis revealed that increased Lp(a) is an independent predictor of lower diabetes incidence (HR 0.39, 95% CI 0.17-0.90, p = 0.02) after adjustment for confounders.

CONCLUSION

Among subjects with FCH those with higher Lp(a) levels have lower risk for the development of type 2 diabetes. Moreover, the presence of increased Lp(a) seems to differentiate the expression of metabolic syndrome characteristics in patients with FCH, as increased Lp(a) is related to lower levels of triglycerides, greater prevalence of hypertension and higher levels of HDL cholesterol.

Ferulic acid improves glucose homeostasis by modulation of key diabetogenic activities and restoration of pancreatic architecture in diabetic rats

There are increasing concerns on the rising cases of diabetes mellitus with type 2 diabetes (T2D) being of major interest as well as the cost of its treatment. Plant phenolic compounds are natural and potent antioxidants that have been widely reported for their antidiabetic activities properties, one of which is ferulic acid. The effect of ferulic acid (FA) on major diabetogenic activities and pancreatic architecture linked to T2D was investigated in T2D rats. T2D was induced in male Sprague-Dawley rats using the fructose-streptozotocin model. Diabetic rats were treated with FA at 150 or 300 mg/kg bodyweight (bw). Normal control consisted of rats administered with food and water, while diabetic control consisted of untreated diabetic rats. Metformin was used as the standard drug. The rats were humanely sacrificed after 5 weeks of treatment. Their blood, liver, and pancreas were collected for analysis. Total glycogen content and carbohydrate metabolic enzymes activities were analyzed in the liver, while the pancreas and serum from blood were analyzed for oxidative stress biomarkers, purinergic and cholinergic enzyme activities, and amylase and lipase activities. The pancreatic tissue was further subjected to microscopic and histological examinations. FA caused a significant (p < 0.05) decrease in blood glucose level, with concomitant increase in serum insulin level. Treatment with FA also led to elevated levels of GSH, HDL-c, SOD, and catalase activities, while concomitantly suppressing malondialdehyde, cholesterol, triglyceride, LDL-c, NO, ALT, AST, creatinine, urea, and uric acid levels, acetylcholinesterase, ATPase, ENTPDase, 5'-nucleotidase, lipase, glycogen phosphorylase, glucose-6-phosphatase, and fructose-1,6-biphosphatase activities. Histology analysis revealed an intact pancreatic morphology in FA-treated diabetic rats. While transmission electron microscopy (TEM) analysis revealed an intact pancreatic ultrastructure and increased number of insulin granules in β-cells. Taken together, these results portray that the antidiabetic potentials of ferulic acid involves modulation of major diabetogenic activities and maintenance of the pancreatic ultrastructure architecture.

Associations among serum insulin, calprotectin, and C-reactive protein concentrations in Miniature Schnauzers with idiopathic hyperlipidemia before and after feeding an ultra-low-fat diet

Background

Miniature Schnauzers (MS) commonly have idiopathic hypertriglyceridemia (HTGL), which is associated with insulin resistance (IR) and a subclinical inflammatory phenotype.

Objectives

Determine the association between indicators of IR and inflammatory biomarkers in MS with and without HTGL and identify how indicators of IR are affected by dietary intervention in MS with HTGL.

Animals

Seventy MS with HTGL and 79 MS without HTGL. In addition, 15 MS with HTGL were placed on a low‐fat diet.

Methods

Serum concentrations of triglycerides, cholesterol, calprotectin, insulin, and glucose were compared between groups.

Results

Serum glucose and calprotectin concentrations (shown to be higher in MS with HTGL than in MS without HTGL) were inversely correlated (ρ = −.28; P < .001). After dietary intervention, median serum insulin concentrations were 8.1 mU/L compared to 20.8 mU/L before dietary intervention (P = .06). Dogs with complete resolution of HTGL after dietary intervention (5 dogs) had significantly lower serum insulin concentrations compared to baseline (P = .03).

Conclusion and Clinical Importance

The subclinical inflammatory phenotype in MS with HTGL appears to be associated with IR. Resolution of HTGL by dietary intervention is associated with a decrease in serum insulin concentrations. The implication of the increase in serum calprotectin concentrations after resolution of HTGL warrants further study.

Altered vascular reactivity to circulating angiotensin II in familial hypercholesterolemia

ABSTRACT

We have previously shown increased vascular reactivity to angiotensin (Ang) II in familial combined hyperlipidemia. However, this has not been well studied in familial hypercholesterolemia (FH), a condition with incipient endothelial dysfunction. This study aimed to examine microvascular and macrovascular responses to Ang II in FH. Therefore, we investigated the effects of a 3h infusion of Ang II on blood pressure and forearm skin microvascular function in 16 otherwise healthy FH patients and matched healthy controls. Skin microvascular hyperaemia was studied by laser Doppler fluxmetry during local heating. Microvascular resistance was determined by the ratio mean arterial pressure/microvascular hyperaemia. Macrovascular reactivity was assessed by changes in brachial blood pressure. Compared to the controls, the FH group had increased baseline systolic blood pressure (127±14 vs 115±12 mmHg; P=0.02), while systolic blood pressure responses were similar (+24±9 vs +21±7 mmHg; P=0.26), after 3 h of Ang II infusion. At baseline, there were no group differences in microvascular hyperaemia or resistance. However, after 3 h of Ang II infusion, heat induced microvascular hyperaemia was less pronounced in FH (126±95 vs 184±102 arbitrary units; P=0.01), while microvascular resistance during heat induced hyperaemia was increased (1.9±0.9 vs 0.9±0.8, P=0.01), as compared to controls. Both these responses were further pronounced 1 h after stopping Ang II. In conclusion, despite similar blood pressure responses to Ang II in FH and controls, microvascular dilatation capacity was impaired in FH, indicating endothelial dysfunction. These findings and increased microvascular resistance may lead to hypertension and microvascular complications in FH.

Familial combined hyperlipidaemia/polygenic mixed hyperlipidaemia

Familial combined hyperlipidaemia (FCH) is the most prevalent form of familial hyperlipidaemia with a multigenic origin and a complex pattern of inheritance. In this respect, FCH is an oligogenic primary lipid disorder due to interaction of genetic variants and mutations with environmental factors. Patients with FCH are at increased risk of cardiovascular disease and often have other associated metabolic conditions. Despite its relevance in cardiovascular prevention, FCH is frequently underdiagnosed and very often undertreated. In this review, emphasis is placed on the most recent advances in FCH, in order to increase its awareness and ultimately contribute to improving its clinical control.

ANGPTL3 gene variants in subjects with familial combined hyperlipidemia

Angiopoietin-like 3 (ANGPTL3) plays an important role in lipid metabolism in humans. Loss-of-function variants in ANGPTL3 cause a monogenic disease named familial combined hypolipidemia. However, the potential contribution of ANGPTL3 gene in subjects with familial combined hyperlipidemia (FCHL) has not been studied. For that reason, the aim of this work was to investigate the potential contribution of ANGPTL3 in the aetiology of FCHL by identifying gain-of-function (GOF) genetic variants in the ANGPTL3 gene in FCHL subjects. ANGPTL3 gene was sequenced in 162 unrelated subjects with severe FCHL and 165 normolipemic controls. Pathogenicity of genetic variants was predicted with PredictSNP2 and FruitFly. Frequency of identified variants in FCHL was compared with that of normolipemic controls and that described in the 1000 Genomes Project. No GOF mutations in ANGPTL3 were present in subjects with FCHL. Four variants were identified in FCHL subjects, showing a different frequency from that observed in normolipemic controls: c.607-109T>C, c.607-47_607-46delGT, c.835+41C>A and c.*52_*60del. This last variant, c.*52_*60del, is a microRNA associated sequence in the 3′UTR of ANGPTL3, and it was present 2.7 times more frequently in normolipemic controls than in FCHL subjects. Our research shows that no GOF mutations in ANGPTL3 were found in a large group of unrelated subjects with FCHL.

Incidence of type 2 diabetes in familial combined hyperlipidemia

OBJECTIVE

Familial combined hyperlipidemia (FCHL) is common among survivors of a premature myocardial infarction. FCHL patients are characterized by visceral obesity, fatty liver, and insulin resistance. The aim of the present study was to determine the incidence and determinants of type 2 diabetes (T2D) in a longitudinal cohort of FCHL pedigrees.

RESEARCH DESIGN AND METHODS

FCHL patients, their unaffected relatives and spouses included in our baseline cohort in 1998-2005 (n=596) were re-invited to determine the incidence of self-reported T2D (that was confirmed by medical records), used as the primary outcome measure. The Fatty Liver Index (FLI) and Homeostasis Model Assessment Insulin Resistance (HOMA2-IR) were used as markers of fatty liver and insulin resistance, respectively. A subset of the original cohort underwent ultrasound of the liver, and subcutaneous and visceral fat in 2002-2005 (n=275; 'ultrasound subcohort').

RESULTS

Follow-up data (median: 15 years) was acquired for 76%. The incidence rate of T2D was significantly higher in FCHL patients compared with spouses (19.2 per 1000 person-years vs 2.8 per 1000 person-years; HR : 6.3, 95% CI: 2.4 to 16.8), whereas no differences were observed between unaffected relatives and spouses (HR: 0.9, 95% CI: 0.3 to 2.6). Cox's proportional hazard regression analyses showed that baseline HOMA2-IR and FLI≥60, but not waist circumference, BMI, or the FCHL affected state, were independently associated with incident T2D. Similar results were obtained in the ultrasound subcohort (median follow-up: 11 years), in which baseline HOMA2-IR and fatty liver (assessed by ultrasound) were independently associated with incident T2D.

CONCLUSION

This study further corroborates the suggestion that the liver plays a central role in the pathogenesis of cardiometabolic complications in FCHL. It supports periodical screening for T2D in this high-risk population.

Edgeworthia gardneri (Wall.) Meisn. Water Extract Ameliorates Palmitate Induced Insulin Resistance by Regulating IRS1/GSK3β/FoxO1 Signaling Pathway in Human HepG2 Hepatocytes

The flower of Edgeworthia gardneri (Wall.) Meisn is commonly used in beverage products in Tibet and has potential health benefits for diabetes. However, the mechanisms underlying anti-insulin resistance (IR) action of the flower of E. gardneri are not fully understood. This study aims to investigate the effects of the water extract of the flower of E. gardneri (WEE) on IR in palmitate (PA)-exposed HepG2 hepatocytes. WEE was characterized by UPLC analysis. PA-treated HepG2 cells were selected as the IR cell model. The cell viability was determined using MTT assay. Moreover, the glucose consumption and production were measured by glucose oxidase method. The glucose uptake and glycogen content were determined by the 2-NBDG (2-deoxy-2-[(7-nitro-2,1,3-benzoxadiazol-4-yl) amino]-D-glucose) glucose uptake assay and anthrone-sulfuric acid assay, respectively. The intracellular triglyceride content was detected by oxidative enzymic method. Protein levels were examined by Western blotting. Nuclear localization of FoxO1 was detected using immunofluorescence analyses and Western blotting. The expression of FoxO1 target genes was detected by quantitative real-time polymerase chain reaction (qRT-PCR). The viability of PA-treated HepG2 cells was concentration-dependently increased by incubation with WEE for 24 h. WEE treatment remarkably increased the consumption and uptake of glucose in PA-exposed HepG2 cells. Moreover, treatment with WEE significantly decreased the PA-induced over-production of glucose in HepG2 cells. After exposure of HepG2 cells with PA and WEE, the glycogen content was significantly elevated. The phosphorylation and total levels of IRβ, IRS1, and Akt were upregulated by WEE treatment in PA-exposed HepG2 cells. The phosphorylation of GSK3β was elevated after WEE treatment in PA-treated cells. WEE treatment also concentration-dependently downregulated the phosphorylated CREB, ERK, c-Jun, p38 and JNK in PA-exposed HepG2 cells. Furthermore, the nuclear protein level and nuclear translocation of FoxO1 were also suppressed by WEE. Additionally, PA-induced changes of FoxO1 targeted genes were also attenuated by WEE treatment. The GLUT2 and GLUT4 translocation were also promoted by WEE treatment in PA-treated HepG2 cells. Taken together, WEE has potential anti-IR effect in PA-exposed HepG2 cells; the underlying mechanism of this action may be associated with the regulation of IRS1/GSK3β/FoxO1 signaling pathway. This study provides a pharmacological basis for the application of WEE in the treatment of metabolic diseases such as type 2 diabetes mellitus.

Familial combined hyperlipidemia: An overview of the underlying molecular mechanisms and therapeutic strategies

Among different types of dyslipidemia, familial combined hyperlipidemia (FCHL) is the most common genetic disorder, which is characterized by at least two different forms of lipid abnormalities: hypercholesterolemia and hypertriglyceridemia. FCHL is an important cause of cardiovascular diseases. FCHL is a heterogeneous condition linked with some metabolic defects that are closely associated with FCHL. These metabolic features include dysfunctional adipose tissue, delayed clearance of triglyceride-rich lipoproteins, overproduction of very low-density lipoprotein and hepatic lipids, and defect in the clearance of low-density lipoprotein particles. There are also some genes associated with FCHL such as those affecting the metabolism and clearance of plasma lipoprotein particles. Due to the high prevalence of FCHL especially in cardiovascular patients, targeted treatment is ideal but this necessitates identification of the genetic background of patients. This review describes the metabolic pathways and associated genes that are implicated in FCHL pathogenesis. We also review existing and novel treatment options for FCHL. © 2019 IUBMB Life, 71(9):1221-1229, 2019.

Insulin resistance in children with familial hyperlipidemia

Background The aim of the study was to investigate whether there is insulin resistance in children with familial hyperlipidemia (FHL) and to determine the factors affecting insulin resistance. Methods Hyperlipidemic children aged between 4 and 18 years and followed up with an FHL diagnosis were included in the study. The children of adults followed up with an FHL diagnosis were also recruited after the screening period. The scanned children were divided into two groups as hyperlipidemic and normolipidemic. A total of 77 patients of whom 52 were hyperlipidemic and 25 were normolipidemic were assessed in the study. Insulin resistance was evaluated (homeostatic model assessment of insulin resistance [HOMA-IR]) by performing the oral glucose tolerance test (OGTT). Results Of the patients, 36 were male and 41 were female; the average age was 11.6±3.9 years, and the body mass index (BMI) was established to be 20.3±4.4. In hyperlipidemic and normolipidemic patients, the following were determined: fasting insulin: 10.6 (±0.89) μU/mL, 4.9 (±0.45) μU/mL (p=0.000); 2-h insulin: 28.7 (±12.7) μU/mL, 18.9 (±10.5) μU/mL (p=0.000); and HOMA-IR: 1.9 (±0.17), 0.86 (±0.7) (p=0.000). No relationship was identified between lipid profiles and insulin resistance. Nevertheless, there was a positive correlation between insulin resistance and apolipoprotein B (Apo B) levels (0.52), and a negative correlation was determined in carnitine levels (-0.64). Conclusions Insulin resistance was established to be higher in children with FHL compared to normolipidemic children. Insulin resistance was not related to lipid phenotypes, but to Apo B levels and carnitine levels. Insulin resistance should be a routine method of evaluation in the follow-up of children with FHL.

Infusion of angiotensin II increases fibrinolysis in healthy individuals but not in patients with familial combined hyperlipidemia

Impaired fibrinolysis is related to insulin resistance, also a characteristic feature of familial combined hyperlipidemia (FCHL). The renin-angiotensin (Ang) system is upregulated with insulin resistance, and there is crosstalk between Ang II and insulin-signalling pathways. We studied the fibrinolytic effects of a 3-h systemic Ang II infusion in 16 patients with FCHL and 16 controls, and placebo infusion in eight individuals. Baseline plasminogen activator inhibitor-1 (PAI-1) activity, plasmin-antiplasmin complex, insulin resistance and C-reactive protein were higher in patients with FCHL than in controls. PAI-1 activity decreased during Ang II, similar in patients with FCHL and controls, and by placebo. Plasmin-antiplasmin complex was unaffected by Ang II in FCHL but increased in controls. Patients with FCHL show signs of insulin resistance, low-grade inflammation and impaired fibrinolysis. Ang II enhances fibrinolysis in controls but not in patients with FCHL, suggesting that patients with FCHL are not capable of increasing tissue plasminogen activator activity in response to Ang II. Ang II has no short-term effects on PAI-1 activity.

Progress in the care of common inherited atherogenic disorders of apolipoprotein B metabolism

Familial hypercholesterolaemia, familial combined hyperlipidaemia (FCH) and elevated lipoprotein(a) are common, inherited disorders of apolipoprotein B metabolism that markedly accelerate the onset of atherosclerotic cardiovascular disease (ASCVD). These disorders are frequently encountered in clinical lipidology and need to be accurately identified and treated in both index patients and their family members, to prevent the development of premature ASCVD. The optimal screening strategies depend on the patterns of heritability for each condition. Established therapies are widely used along with lifestyle interventions to regulate levels of circulating lipoproteins. New therapeutic strategies are becoming available, and could supplement traditional approaches in the most severe cases, but their long-term cost-effectiveness and safety have yet to be confirmed. We review contemporary developments in the understanding, detection and care of these highly atherogenic disorders of apolipoprotein B metabolism.

Glucose-dependent leukocyte activation in patients with type 2 diabetes mellitus, familial combined hyperlipidemia and healthy controls

BACKGROUND

Leukocyte activation has been associated with vascular complications in type 2 diabetes mellitus (T2DM). Hyperglycemia may be involved in this leukocyte activation. Our aim was to investigate the role of elevated glucose concentrations on leukocyte activation in patients with a wide range of insulin sensitivity.

METHODS

Leukocyte activation was determined after ingestion of 75 gram glucose in subjects with T2DM, familial combined hyperlipidemia (FCH) and healthy controls. Leukocyte activation markers were measured by flow cytometry. Postprandial changes were calculated as the area under the curve (AUC), and the incremental area under the curve corrected for baseline values (dAUC).

RESULTS

51 Subjects (20 T2DM, 17 FCH and 14 controls) were included. Fasting neutrophil CD66b expression and CD66b-AUC were respectively 36% and 39% higher in T2DM patients than in controls (p=0.004 and p=0.003). Fasting neutrophil CD66b expression correlated positively with glucose-AUC (Spearman's rho 0.481, p<0.001) and HbA1c (rho 0.433, p=0.002). Although fasting monocyte CD11b expression was not significantly different between subjects, monocyte CD11b-AUC was 26% higher in T2DM than in controls (p=0.006). Similar trends were observed for FCH patients. Monocyte CD11b-dAUC correlated positively with glucose-AUC (rho 0.322, p=0.022) and HbA1c (rho 0.319, p=0.023).

CONCLUSIONS

These data suggest that both acute and chronic hyperglycemia, associated with insulin resistance as seen in T2DM and FCH, are involved in the increased fasting and postprandial leukocyte activation observed in these conditions.

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.

New therapies targeting apoB metabolism for high-risk patients with inherited dyslipidaemias: what can the clinician expect?

Apolipoprotein B (apoB) has a key role in the assembly and secretion of very low-density lipoprotein (VLDL) from the liver. Plasma apoB concentration affects the number of circulating atherogenic particles, and serves as an independent predictor of the risk of atherosclerotic cardiovascular disease. While statins are the most potent apoB-lowering agents currently prescribed, their efficacy in achieving therapeutic targets for low-density lipoprotein cholesterol (LDL-C) in high-risk patients, such as those with familial hypercholesterolaemia (FH), is limited. Resistance and intolerance to statins also occurs in a significant number of patients, necessitating new types of lipid-lowering therapies. Monoclonal antibodies against proprotein convertase subtilisin/kexin type 9 (PCSK9; AMG 145 and REGN727), a sequence-specific antisense oligonucleotide against apoB mRNA (mipomersen) and a synthetic inhibitor of microsomal triglyceride transfer protein (MTTP; lomitapide) have been tested in phase III clinical trials, particularly in patients with FH. The trials demonstrated the efficacy of these agents in lowering apoB, LDL-C, non-high-density lipoprotein cholesterol and lipoprotein(a) by 32-55 %, 37-66 %, 38-61 % and 22-50 % (AMG 145), 21-68 %, 29-72 %, 16-60 % and 8-36 % (REGN727), 16-71 %, 15-71 %, 12-66 % and 23-49 % (mipomersen) and 24-55 %, 25-51 %, 27-50 % and 15-19 % (lomitapide), respectively. Monoclonal antibodies against PCSK9 have an excellent safety profile and may be indicated not only in heterozygous FH, but also in statin-intolerant patients and those with other inherited dyslipidemias, such as familial combined hyperlipidaemia and familial elevation in Lp(a). Mipomersen and lomitapide increase hepatic fat content and are at present indicated for treating adult patients with homozygous FH alone.

ESR1 gene and insulin resistance remission are associated with serum uric acid decline for severely obese patients undergoing bariatric surgery

BACKGROUND

Hyperuricemia is associated with obesity. Few studies have reported the effects of different types of bariatric surgery on uric acid metabolism. The aim of our study was to determine the relationships between serum uric acid reduction and estrogen receptor-α (ESR1) gene polymorphism, as well as the type of bariatric surgery received. The potential physiological pathways involved in postsurgery serum uric acid reduction were also discussed.

METHODS

A total of 508 severely obese Han Chinese patients, aged 20 to 50 years, with a body mass index (BMI)≥35 kg/m(2) were selected. Patients received either laparoscopic adjustable gastric banding (LAGB; n = 164) or laparoscopic mini-gastric bypass (LMGB; n = 344). A 12-month follow-up was performed to explore the effects of the type of bariatric surgery and ESR1 polymorphism on serum uric acid reduction.

RESULTS

The rs712221 polymorphism of ESR1 affects serum uric acid reduction after bariatric surgery. The LMGB group exhibited a greater reduction in serum uric acid level compared with the LAGB counterpart after adjusting for sex, age, and metabolic confounders (-2.3 ± 2.1 mg/dL versus-1.2 ± 1.1 mg/dL; P = .002). Patients with the rs712221 genotype exhibited better glycemic control and a greater serum uric acid reduction at 12 months after surgery. The effects of the rs712221 polymorphism in LMGB patients resulted in the greatest serum uric acid reduction (-2.7 ± 1.4 mg/dL).

CONCLUSIONS

For severely obese Han Chinese patients, bariatric surgery appears to reduce serum uric acid levels, potentially mediated by synergic effects of surgery type, BMI reduction, rs712221 locus, insulin sensitivity, and changed dietary factors via an unknown mechanism.

Plasma sterol evidence for decreased absorption and increased synthesis of cholesterol in insulin resistance and obesity

BACKGROUND

The rise in LDL with egg feeding in lean insulin-sensitive (LIS) participants is 2- and 3-fold greater than in lean insulin-resistant (LIR) and obese insulin-resistant (OIR) participants, respectively.

OBJECTIVE

We determined whether differences in cholesterol absorption, synthesis, or both could be responsible for these differences by measuring plasma sterols as indexes of cholesterol absorption and endogenous synthesis.

DESIGN

Plasma sterols were measured by gas chromatography-mass spectrometry in a random subset of 34 LIS, 37 LIR, and 37 OIR participants defined by the insulin sensitivity index (S(I)) and by BMI criteria selected from a parent group of 197 participants. Cholestanol and plant sterols provide a measure of cholesterol absorption, and lathosterol provides a measure of cholesterol synthesis.

RESULTS

The mean (±SD) ratio of plasma total absorption biomarker sterols to cholesterol was 4.48 ± 1.74 in LIS, 3.25 ± 1.06 in LIR, and 2.82 ± 1.08 in OIR participants. After adjustment for age and sex, the relations of the absorption sterol-cholesterol ratios were as follows: LIS > OIR (P < 0.001), LIS > LIR (P < 0.001), and LIR > OIR (P = 0.11). Lathosterol-cholesterol ratios were 0.71 ± 0.32 in the LIS participants, 0.95 ± 0.47 in the LIR participants, and 1.29 ± 0.55 in the OIR participants. After adjustment for age and sex, the relations of lathosterol-cholesterol ratios were as follows: LIS < OIR (P < 0.001), LIS < LIR (P = 0.03), and LIR < OIR (P = 0.002). Total sterol concentrations were positively associated with S(I) and negatively associated with obesity, whereas lathosterol correlations were the opposite.

CONCLUSIONS

Cholesterol absorption was highest in the LIS participants, whereas cholesterol synthesis was highest in the LIR and OIR participants. Therapeutic diets for hyperlipidemia should emphasize low-cholesterol diets in LIS persons and weight loss to improve S(I) and to decrease cholesterol overproduction in LIR and OIR persons.

Plasma proprotein convertase subtilisin kexin type 9 is a heritable trait of familial combined hyperlipidaemia

The aim of the present study was to investigate the relationship between circulating PCSK9 (proprotein convertase subtilisin kexin type 9) and FCHL (familial combined hyperlipidaemia) and, when positive, to determine the strength of its heritability. Plasma PCSK9 levels were measured in FCHL patients (n=45), NL (normolipidaemic) relatives (n=139) and their spouses (n=72). In addition, 11 FCHL patients were treated with atorvastatin to study the response in PCSK9 levels. PCSK9 levels were higher in FCHL patients compared with NL relatives and spouses: 96.1 compared with 78.7 and 82.0 ng/ml (P=0.004 and P=0.002 respectively). PCSK9 was significantly associated with both TAG (triacylglycerol) and apolipoprotein B levels (P<0.001). The latter relationship was accounted for by LDL (low-density lipoprotein)–apolipoprotein B (r=0.31, P=0.02), not by VLDL (very-low-density lipoprotein)–apolipoprotein B (r=0.09, P=0.49) in a subgroup of subjects (n=59). Heritability calculations for PCSK9 using SOLAR and FCOR software yielded estimates of 67–84% respectively (P<0.0001). PCSK9 increased from 122 to 150 ng/ml in 11 FCHL patients treated with atorvastatin (40 mg) once daily for 8 weeks (P=0.018). In conclusion, plasma PCSK9 is a heritable trait associated with both FCHL diagnostic hallmarks. These results, combined with the significant rise in PCSK9 levels after statin therapy, warrant further studies in order to unravel the exact role of PCSK9 in the pathogenesis and treatment of this highly prevalent genetic dyslipidaemia.

Novel drugs in familial combined hyperlipidemia: lessons from type 2 diabetes mellitus

PURPOSE OF REVIEW

Familial combined hyperlipidemia (FCHL) and type 2 diabetes mellitus (T2DM) are prevalent entities that share many features of the metabolic syndrome. Recent findings suggest that FCHL and T2DM are less distinct than initially anticipated, which could offer new insights for their therapeutic approach.

RECENT FINDINGS

Genetic association studies have provided evidence for a common genetic background (upstream transcription factor 1, activating transcription factor 6, transcription factor 7-like 2 and hepatocyte nuclear factor 4 alpha) between FCHL and T2DM. The metabolic overlap can be illustrated by the presence of ectopic fat accumulation and insulin resistance (muscle, adipose tissue and liver). We have shown that FCHL patients are at increased risk to develop T2DM. This indicates that both entities are not static, but instead the former is able to migrate to the latter as insulin resistance progresses. Given these new findings, it can be anticipated that FCHL patients could also benefit from insulin-sensitizing therapy such as pioglitazone and metformin. Indeed, pilot studies have demonstrated that pioglitazone might be advantageous in FCHL patients.

SUMMARY

Recent studies suggest that FCHL patients have an increased risk to develop T2DM, which has important clinical implications. Further studies are necessary to evaluate whether FCHL patients can be protected from new-onset T2DM and premature cardiovascular events with insulin-sensitizing therapy.

The role of insulin resistance in the pathogenesis of atherosclerotic cardiovascular disease: an updated review

Insulin resistance is the main pathologic mechanism that links the constellation of clinical, metabolic and anthropometric traits with increased risk for cardiovascular disease and type II diabetes mellitus. These traits include hyperinsulinemia, impaired glucose intolerance, endothelial dysfunction, dyslipidemia, hypertension, and generalized and upper body fat redistribution. This cluster is often referred to as insulin resistance syndrome. The progression of insulin resistance to diabetes mellitus parallels the progression of endothelial dysfunction to atherosclerosis leading to cardiovascular disease and its complications. In fact, insulin resistance assessed by homeostasis model assessment (HOMA) has shown to be independently predictive of cardiovascular disease in several studies and one unit increase in insulin resistance is associated with a 5.4% increase in cardiovascular disease risk. This review article addresses the role of insulin resistance as a main causal factor in the development of metabolic syndrome and endothelial dysfunction, and its relationship with cardiovascular disease. In addition to this, we review the type of lifestyle modification and pharmacotherapy that could possibly ameliorate the effect of insulin resistance and reverse the disturbances in insulin, glucose and lipid metabolism.

Serum ferritin is a major determinant of lipid phenotype in familial combined hyperlipidemia and familial hypertriglyceridemia

Familial combined hyperlipidemia (FCH) and familial hypertriglyceridemia (FHTG) share pathogenic mechanisms and a high interaction with components of the metabolic syndrome. The metabolic syndrome associates increased serum ferritin concentration and high cardiovascular risk. The objective was to describe the frequency of iron overload and the relationship between serum ferritin and the phenotype in patients with FCH and FHTG. The study was composed of 211 consecutive unrelated patients aged at least 18 years with primary hypertriglyceridemia, 149 with FCH, and 62 with FHTG. The prevalence of the metabolic syndrome and hyperferritinemia was very high in both hypertriglyceridemic groups (51.7% and 20.1% in FCH and 62.9% and 16.1% in FHTG, respectively), without significant statistical differences between them. Serum ferritin concentration did not show any significant association with the number of metabolic syndrome criteria. Subjects in the highest tertile of ferritin concentration (ferritin >200 mug/L) presented higher concentrations of triglycerides and liver enzymes than subjects in the first tertile of ferritin concentration (ferritin <90 mug/L). The highest positive correlation coefficient for triglycerides was found with ferritin in FCH and in FHTG subjects (R = 0.317 [P < .001] when combined). Ferritin was also the covariate that showed the highest independent association with triglycerides in FCH and FHTG. In contrast, ferritin was not associated with carotid intima-media thickness. In summary, serum ferritin is commonly increased in FCH and in FHTG, it is not related with the presence of metabolic syndrome, and it is highly correlated with liver enzymes.

Serum adiponectin is decreased in patients with familial combined hyperlipidemia and normolipaemic relatives and is influenced by lipid-lowering treatment

BACKGROUND AND AIMS

Hypoadiponectinemia has been reported in patients with familial combined hyperlipidemia (FCHL) presenting increased waist circumference and insulin resistance. However, no studies have evaluated this association in non-obese FCHL patients. Moreover, it is unclear whether correction of lipoprotein abnormalities may influence adiponectin levels in FCHL.

METHODS AND RESULTS

We have compared serum levels of adiponectin in 199 non-obese FCHL patients (BMI 25.96+/-3.7), 116 normolipaemic (NL) non-affected relatives (BMI 24.4+/-4.0) and 192 controls (BMI 28.0+/-7.4). In a subgroup of FCHL patients, changes in adiponectin levels after treatment with atorvastatin (n=22) or fenofibrate (n=26) were also evaluated. FCHL patients as well as their NL relatives showed lower serum adiponectin levels compared to controls (9.7+/-5.4 microg/mL, 10.7+/-5.3 microg/mL and 17.3+/-13.7microg/mL, respectively; p<0.0001 for all comparisons). After controlling for confounders, the strongest association with hypoadiponectinemia was observed with family history of FCHL, followed by HDL-C (negatively) and age (positively). These variables jointly explained 15% of the total variance of serum adiponectin levels. After 24-week of treatment, adiponectin was increased by 12.5% (p<0.05) by atorvastatin and was reduced by 10% by fenofibrate, resulting in a treatment difference of 22.5% in favor of atorvastatin (p<0.017).

CONCLUSIONS

FCHL patients showed lower serum adiponectin levels compared to controls. Also normolipaemic relatives of FCHL patients presented decreased levels of adiponectin, suggesting a possible common background in the determination of this abnormality. Overall, these observations indicate that hypoadiponectinemia may be an inherent characteristic of the FCHL phenotype. In FCHL patients hypoadiponectinemia may be partially corrected by atorvastatin but not by fenofibrate treatment.

Combined hyperlipidemia in relation to race/ethnicity, obesity, and insulin resistance in the Multi-Ethnic Study of Atherosclerosis

We have asked whether the prevalence of combined hyperlipidemia (CHL) differs by race/ethnicity, obesity, and insulin resistance in a contemporary, multiethnic, US cohort. We determined the prevalence and adjusted odds of CHL in a cohort of 5923 men and women free of clinically recognized cardiovascular disease and diabetes according to race/ethnicity (white, Chinese, African American, and Hispanic), obesity, and insulin resistance. Untreated lipid values were imputed for those on lipid-lowering therapy. Combined hyperlipidemia was defined using age- and sex-specific greater than or equal to 75th percentile cut points for low-density lipoprotein cholesterol and triglycerides obtained from a predominantly white North American population study. Compared with whites, adjusted odds ratios for CHL were 0.48 in African Americans (95% confidence interval [CI], 0.30-0.75), 1.33 in Hispanics (95% CI, 0.93-1.91), and 1.06 in Asians (95% CI, 0.62-1.82). Within the entire population, the adjusted odds of CHL were over 2-fold higher in overweight and obese participants compared with normal-weight participants and more than 4-fold higher in quartiles 2 through 4 of insulin resistance compared with quartile 1. African Americans had lower odds for CHL than whites despite higher body mass index and abdominal adiposity. Hispanics had a nonsignificantly higher trend, and Asians had no significantly different odds than whites. Modest increases in weight and insulin resistance were associated with significantly higher odds of CHL in a multiethnic US population. Further research is needed to determine the most efficacious diet, exercise, and drug management to decrease the risk of CHL and coronary heart disease among racial/ethnic groups in the United States.

Parabolic relationship between plasma triacylglycerols and LDL-cholesterol in familial combined hyperlipidaemia: the multiple-type hyperlipidaemia explained?

FCHL (familial combined hyperlipidaemia) is a highly prevalent genetic lipid disorder that accounts for a substantial number of premature cardiovascular events. To date, FCHL has been complicated by the different lipid phenotypes that are present within one family and one individual patient over time. In the present study, we hypothesized that a parabolic relationship between plasma triacylglycerols (triglycerides) and LDL (low-density lipoprotein)-cholesterol can explain this so-called ‘multiple-type hyperlipidaemia’ in FCHL. Our hypothesis was tested in two well-documented FCHL cohorts [Maastricht (n=145) and Nijmegen (n=299)] that were followed over a 5-year interval. Three groups were constructed depending on plasma triacylglycerols: group A (individuals with both measurements below 1.5 mmol/l), group B (one measurement below and one measurement above 1.5 mmol/l) and group C (both measurement above 1.5 mmol/l). In both male, but not female, cohorts, a significant positive relationship between plasma triacylglycerols and LDL-cholesterol was observed in group A (P=0.02 for Maastricht cohort and P=0.001 for the Nijmegen cohort), a significant negative relationship in group C (P=0.01 for Maastricht cohort and P=0.02 for the Nijmegen cohort), and a relationship intermediate to group A and C in group B. In contrast, both apoB (apolipoprotein B) levels and the prevalence of cardiovascular disease were related with plasma triacylglycerols in a more linear fashion. In conclusion, a parabolic relationship between plasma triacylglycerols and LDL-cholesterol explains the ‘multiple-type hyperlipidaemia’ in FCHL. In addition, the linear relationship between triacylglycerols and both apoB levels and the prevalence of cardiovascular disease substantiate the use of apoB instead of LDL-cholesterol in the diagnosis of FCHL and the prediction of cardiovascular disease.

Elevated LDL-cholesterol level predicts diabetes in centrally obese women but not men: relative roles of insulin resistance and central obesity

BACKGROUND

The aim was to investigate the sex-specific effect of hypercholesterolemia interacting with abdominal obesity (AO) in predicting Type 2 diabetes mellitus (DM). The 3,048 participants (aged > or =28 years) were free of DM at baseline, a representative sample of Turkish adults and were evaluated prospectively.

METHODS AND RESULTS

As cut-off points for AO were used > or =95 cm in men and > or =91 cm in women, and for hypercholesterolemia > or =5.2 mmol/L. Diabetes was diagnosed using criteria of the American Diabetes Association. Four groups were formed at baseline: Group I subjects had neither AO nor hypercholesterolemia (33.3%), Group II subjects had AO only (27.6%), Group III subjects had hypercholesterolemia only (17.8%), and Group IV subjects had AO combined with hypercholesterolemia (21.3%). Over a mean of 5.9 years, DM developed in 103 women and 116 men. An age-adjusted relative risk (RR) by logistic regression for DM in the 4 groups, using AO as a reference group, disclosed an RR of 1.88 (95% confidence interval 1.14; 3.09) in women and an insignificant RR 1.29 in men (women were predicted to be 1.46 times more likely to develop DM). Hypercholesterolemia alone did not differ significantly from Group I in its ability to predict diabetes. An elevated level of low-density lipoprotein (LDL)-cholesterol (C) (> or =3.4 mmol/L) was delineated as the element associated with diabetes in hypercholesterolemia by multiple logistic regression. The identification of 48 participants with familial-combined hyperlipidemia phenotypes alone could not account for most of the centrally obese and hypercholesterolemic women developing DM.

CONCLUSION

It was suggested that a diminished effectiveness of insulin resistance in centrally obese Turkish women (but not men) might predispose them to an elevation in LDL concentrations, while other features of visceral adiposity still predispose them to DM. In summary, an elevated LDL-C level interacts with AO in Turkish women to enhance the development of diabetes.

Five-year follow-up of waist circumference, insulin and ALT levels in familial combined hyperlipidaemia

FCHL (familial combined hyperlipidaemia), an entity with many features of the metabolic syndrome, is characterized by changes in cholesterol and triacylglycerol (triglyceride) phenotype over time. The present study was conducted to investigate the relationship of ALT (alanine aminotransferase) levels, used as a surrogate marker for the amount of hepatic fat, with the switch in triacylglycerol phenotype and the increased susceptibility to develop hypertriglyceridaemia in FCHL. BMI (body mass index), waist circumference and plasma triacylglycerols, insulin and ALT levels were measured in 145 FCHL family members and 54 spouses at baseline and after a 5-year follow-up. A switch from normotriglyceridaemia to hypertriglyceridaemia or vice versa, as observed in 22 of 145 FCHL family members, was associated with changes in plasma ALT levels (P=0.001), but not with insulin levels or waist circumference. At 5 years of follow-up, an intra-individual relationship was observed between waist circumference and plasma triacylglycerols, insulin and ALT levels. For each waist circumference, FCHL patients, but not their NL (normolipidaemic) relatives, exhibited higher triacylglycerol and insulin levels than spouses (P<0.001). Remarkably, both FCHL patients and the NL relatives had higher ALT levels for each waist circumference compared with spouses (P<0.001 for FCHL patients, and P=0.035 for NL relatives). In conclusion, the present study shows that the longitudinal relationship of abdominal obesity–ALT is more specific for all FCHL family members, i.e. patients and their NL relatives, than the relationship of abdominal obesity–triacylglycerols. Additionally, the association of ALT with the switch in triacylglycerol phenotype suggests a central role of the liver in the pathogenesis of FCHL.

Increased intestinal cholesterol absorption in autosomal dominant hypercholesterolemia and no mutations in the low-density lipoprotein receptor or apolipoprotein B genes

CONTEXT

Autosomal dominant hypercholesterolemia (ADH) is frequently caused by functional mutations in the low-density lipoprotein receptor (LDLR) or apolipoprotein B-100 (APOB) genes, but approximately 40% of ADH subjects disclose no such molecular defects, possibly pointing to alternative genetic mechanisms.

OBJECTIVE

Our objective was to test the hypothesis that increased intestinal cholesterol absorption might play a role in the lipid abnormalities of subjects with ADH without identified genetic defects.

DESIGN AND SETTING

This is a cross-sectional study of consecutive subjects with primary hyperlipidemia identified during an 18-month period in two lipid clinics.

STUDY SUBJECTS

A total of 52 subjects with a clinical diagnosis of ADH were examined for molecular defects in LDLR and APOB. No APOB defects were found. Functional LDLR mutations occurred in 31 (60%) subjects, who received a diagnosis of familial hypercholesterolemia (FH). Those for whom no mutations could be identified were labeled as non-FH ADH. In addition, 38 subjects with familial combined hyperlipidemia (FCH) and 45 normolipidemic control subjects were studied.

INTERVENTIONS

Interventions were diagnostic.

MAIN OUTCOME MEASURES

Serum noncholesterol sterols were used as markers for the efficiency of intestinal cholesterol absorption.

RESULTS

Adjusted campesterol to cholesterol ratios increased in the order non-FH ADH more than FH more than controls more than FCH, with mean values (95% confidence interval) in 10(2) mmol/mol cholesterol of 505 (424-600), 397 (345-458), 335 (294-382), and 284 (247-328), respectively. Thus, cholesterol absorption was lowest in FCH and highest in non-FH ADH.

CONCLUSIONS

Increased intestinal cholesterol absorption may partially explain the high cholesterol levels of non-FH ADH subjects. Serum noncholesterol sterols are a useful tool for the differential diagnosis of genetic hypercholesterolemias, especially FCH and ADH unrelated to LDLR or APOB defects.

Diet-induced increases in adiposity, but not plasma lipids, promote macrophage infiltration into white adipose tissue

Obesity, hyperlipidemia, and insulin resistance are cardinal features of the metabolic syndrome and individually increase the risk for developing diabetes and cardiovascular disease, a risk that is amplified when they are simultaneously present. It is becoming increasingly clear that macrophages can infiltrate white adipose tissue (WAT) in the obese state, and their presence is associated with pathophysiological consequences of obesity, such as inflammation and insulin resistance. To determine whether hyperlipidemia could potentiate macrophage infiltration into WAT in the presence of obesity, obesity-prone agouti yellow mice (A(y)/a) on a hyperlipidemia-prone LDL receptor (LDLR)-deficient (LDLR(-/-)) background were placed on chow or Western diet. In addition, A(y)/a mice that were LDLR sufficient were also placed on Western diet. Both genetics and diet increased the degree of adiposity; however, plasma lipids were elevated only in the Western diet-fed LDLR(-/-) mice. The extent of macrophage accumulation in WAT correlated with the degree of adiposity. However, hyperlipidemia did not impact macrophage recruitment to WAT or the downstream metabolic consequences of macrophage accumulation in WAT, such as inflammation and insulin resistance. These data have important implications for the pathogenesis of diet-induced obesity in humans, even when plasma lipid abnormalities are not present.

Metabolic syndrome prevalence and characteristics in Greek adults with familial combined hyperlipidemia

Familial combined hyperlipidemia (FCH) is closely related with metabolic syndrome (MetSyn), and coronary artery disease (CAD) is positively associated to MetSyn and FCH. In this study, we evaluated the prevalence of MetSyn and its components between patients with FCH and a control group. We also investigated the role of MetSyn and diabetes mellitus (DM) on the incidence of CAD within the FCH group. Our study population consisted of 463 male and 243 female patients with FCH who were not receiving any hypolipidemic treatment, and 1128 men and 1154 women who came from the same geographical region. The prevalence of MetSyn was 42% and 19.8% among FCH subjects and controls, respectively, whereas MetSyn increased with age in both groups. The prevalence of CAD was 15.3% in the FCH group. Moreover, after dividing FCH patients into 3 subgroups, with and without MetSyn and with DM, CAD prevailed at a percentage of 15.2%, 11.1%, and 26.5%, respectively. However, statistically significant differences in the prevalence of CAD were observed only between FCH subjects with DM compared with the other 2 subgroups, even when an adjustment for age, sex, and smoking was conducted. People with FCH and MetSyn differed in several anthropometric, biochemical, and clinical characteristics, compared with the non-MetSyn subgroup of FCH. MetSyn is more prevalent in the FCH than in the control group. Among subjects with FCH, only DM was significantly associated with an increase in the prevalence of CAD in this subgroup compared with FCH individuals with or without MetSyn.

Relationship Between Lipid Abnormalities and Insulin Resistance in Japanese School Children

Objective— Dyslipidemia and insulin resistance (IR) are risk factors for coronary heart disease (CHD) in adults. To help prevent the development of CHD, it may be useful to understand the relationship between lipid abnormalities and IR during childhood.

Methods and Results— IR was assessed by the homeostasis model approximation index. We studied 1175 Japanese school children (642 boys and 533 girls), aged between 7 and 12 years. Obesity was defined by the body mass index standard deviation score (BMISD) (obese: BMISD ≥2.0). BMISD was most significantly associated with IR in nonobese children ( P =0.000). Associations of IR with lipid-related parameters were affected by BMISD. After being corrected by BMISD, in nonobese children, log triglycerides (TG), apoB and low-density lipoprotein (LDL) size in boys and log TG, LDL size, and high-density lipoprotein (HDL) cholesterol in girls were still significantly associated with IR ( P =0.000 to 0.017). In obese children, all parameters except for LDL cholesterol in boys and LDL size in girls were significantly associated with IR ( P =0.000 to 0.030). Multiple regression analysis showed that log TG and LDL size in nonobese children, log TG in obese boys and LDL size in obese girls were independently associated with IR. Children with IIb and IV hyperlipidemia had significantly higher IR than those with normolipidemia and IIa, even after correcting for BMISD and age.

Conclusion— Our results suggest that in addition to controlling body weight, it may be important for school children to characterize lipid phenotypes to prevent progression to CHD and/or type 2 diabetes and to identify subjects who are at high risk for these disorders.

Small dense low-density lipoprotein and its role as an independent predictor of cardiovascular disease

PURPOSE OF REVIEW

This review discusses whether the relationship of small dense low-density lipoprotein to cardiovascular risk is direct, due to the atherogenic properties of the particle, or a reflection of concomitant abnormalities in high-density lipoprotein and plasma triglyceride.

RECENT FINDINGS

Recent studies have examined whether low-density lipoprotein size distribution or concentration of small low-density lipoprotein is related more strongly to risk. It appears that the latter is a better predictor in major surveys, although in smaller cohort studies particle size shows a strong association with atherosclerosis burden. While the main causes of the formation of small dense low-density lipoprotein are relatively well understood, novel metabolic factors may also play a role, and pharmacologic interventions such as glitazones may have a direct regulatory impact.

SUMMARY

Evidence links abnormalities in low-density lipoprotein structure to cardiovascular risk. The plasma concentration of small dense low-density lipoprotein is likely to be more informative than relative low-density lipoprotein particle size, and although methods are available for quantitation of this subfraction, there is considerable room for improvement. It is not yet clear how knowledge of the small dense low-density lipoprotein concentration may add to risk prediction.

[Treatment of dyslipidemia: how and when to combine lipid lowering drugs]

Familial combined hyperlipidemia (FCH) is a frequent familial lipid disorder associated with insulin resistance, low HDL cholesterol, high triglycerides and cholesterol levels with variable phenotypes within the same family. FCH is linked to a high risk for cardiovascular diseases. Treatment goals for lipid abnormalities are changing in recent years. Lowering elevated levels of LDL e Non HDL-cholesterol levels are primary targets of therapy. Lower LDL-C than 70 mg/dL seems to be useful to lower cardiovascular risk in patients with very high risk. Many statins are available, with different potencies and drug interactions. Combination therapy of statins and bile acid sequestrants or ezitimibe may be necessary to further decrease LDL cholesterol levels in order to meet guideline goals. High triglycerides and low HDL cholesterol are also important goals in the treatment of these patients, and frequently statins alone are insufficient to normalize the lipid profile. Combination therapy with fibrates will further lower triglycerides and increase HDL cholesterol levels; this combination is also associated with higher incidence of myopathy and liver toxicity; appropriate evaluation of patients' risk and benefits is necessary. Association of statin/niacin seems be very useful in patients with FCH, especially as niacin is the best drug to increase HDL cholesterol; this association is not linked to a higher frequency of myopathy. Niacin causes flushing, that can in part be managed with use of aspirin and extended release forms (Niaspan); niacin also may increase plasma glucose and uric acid levels. Evaluation of risks and benefits for each patient is needed.

Effects of rosuvastatin on endothelial function in patients with familial combined hyperlipidaemia (FCH)

OBJECTIVE

Although several studies have reported a positive effect of statins on endothelial vasoreactivity, most studies performed in subjects with type 2 diabetes mellitus report no effect at all. This lack of effect may be related to the existence of insulin resistance, or to insufficient lowering of atherogenic (apo)lipoproteins. Therefore, we tested in this study whether treatment of insulin resistant familial combined hyperlipidaemia (FCH) patients with a high dose (40 mg/day) of the potent rosuvastatin was able to improve endothelial function, without necessarily improving insulin sensitivity.

RESEARCH DESIGN AND METHODS

In a double-blind randomised crossover study, 18 subjects with FCH (without evident cardiovascular disease, mean [standard deviation] age 54 [7] years) underwent a 4-week run-in period after which they were randomised to treatment with placebo once daily for 12 weeks, followed by rosuvastatin 40 mg/day for 12 weeks or vice versa. Endothelial function was determined after 8 and 12 weeks of both treatment periods, respectively, by measurement of flow-mediated vasodilation (FMD) using high-resolution ultrasound and by measurement of vasodilator response to intrabrachial acetylcholine (Ach) by venous occlusion plethysmography (forearm blood flow [FBF]).

RESULTS

Plasma levels of lipids, (apo)lipoproteins and high-sensitivity C-reactive protein (hsCRP) improved significantly after rosuvastatin therapy compared to placebo. However, rosuvastatin had no effect on homeostasis model assessment (HOMA)-indices or on vasodilator responses to intra-brachial acetylcholine-infusion (FBF-ratio increased from a mean of 1.28 [SD: 0.46] to 5.82 [3.44] after rosuvastatin and from 1.33 [0.67] to 5.99 [3.89] after placebo, p = 0.35). Endothelium-dependent FMD was also unchanged (1.6% [3.1%] vs. 3.2% [3.5]%, p = 0.56 rosuvastatin vs. placebo, respectively).

CONCLUSION

In patients with FCH, a 12-week treatment of rosuvastatin 40 mg/day did not improve endothelial function (either in large conduit vessels or in resistance vessels), despite significant improvements in plasma lipids, (apo)lipoproteins. and low-grade inflammation.

Decreased adiponectin levels in familial combined hyperlipidemia patients contribute to the atherogenic lipid profile

Familial combined hyperlipidemia (FCH) is characterized by increased levels of total cholesterol, triglycerides, and/or apolipoprotein B. Other features of FCH are obesity and insulin resistance. Adiponectin is a secretory product of the adipose tissue. Low levels of adiponectin are associated with insulin resistance and accelerated atherosclerosis. The aim of this study was to determine whether decreased adiponectin levels are associated with FCH and its phenotypes. The study population comprised 644 subjects, including 158 patients with FCH. Serum adiponectin levels were determined using a commercially available ELISA. For both males and females, the mean adiponectin level (microg/ml) was significantly lower in FCH patients [2.0 (1.8-2.2) and 2.5 (2.3-2.8), respectively] compared with normolipidemic relatives [2.3 (2.2-2.5) and 3.1 (2.8-3.3), respectively] and spouses [2.4 (2.1-2.7) and 3.2 (2.8-3.6), respectively]. These differences remain significant after adjusting for waist circumference and insulin resistance. Low adiponectin level in FCH patients was a superior independent predictor of the atherogenic lipid profile, including high triglyceride levels, low HDL-cholesterol levels, and the amount of small, dense LDL present, compared with both obesity and insulin resistance. Low adiponectin levels may contribute to the atherogenic lipid profile in FCH, independent of insulin resistance and obesity, as measured by waist circumference. This finding implies a role of adipose tissue metabolism in the pathophysiology of FCH.