Atherosclerosis seems not to be associated with hyperinsulinaemia in patients with familial hypercholesterolaemia

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.

Effect of mipomersen on LDL-cholesterol in patients with severe LDL-hypercholesterolaemia and atherosclerosis treated by lipoprotein apheresis (The MICA-Study)

BACKGROUND AND AIMS

In this study, we evaluated the effect of mipomersen in patients with severe LDL-hypercholesterolaemia and atherosclerosis, treated by lipid lowering drugs and regular lipoprotein apheresis.

METHODS

This prospective, randomized, controlled phase II single center trial enrolled 15 patients (9 males, 6 females; 59 ± 9 y, BMI 27 ± 4 kg/m²) with established atherosclerosis, LDL-cholesterol ≥130 mg/dL (3.4 mmol/L) despite maximal possible drug therapy, and fulfilling German criteria for regular lipoprotein apheresis. All patients were on stable lipid lowering drug therapy and regular apheresis for >3 months. Patients randomized to treatment (n = 11) self-injected mipomersen 200 mg sc weekly, at day 4 after apheresis, for 26 weeks. Patients randomized to control (n = 4) continued apheresis without injection. The primary endpoint was the change in pre-apheresis LDL-cholesterol.

RESULTS

Of the patients randomized to mipomersen, 3 discontinued the drug early (<12 weeks therapy) for side effects. For these, another 3 were recruited and randomized. Further, 4 patients discontinued mipomersen between 12 and 26 weeks for side effects (moderate to severe injection site reactions n = 3 and elevated liver enzymes n = 1). In those treated for >12 weeks, mipomersen reduced pre-apheresis LDL-cholesterol significantly by 22.6 ± 17.0%, from a baseline of 4.8 ± 1.2 mmol/L to 3.7 ± 0.9 mmol/L, while there was no significant change in the control group (+1.6 ± 9.3%), with the difference between the groups being significant (p=0.006). Mipomersen also decreased pre-apheresis lipoprotein(a) (Lp(a)) concentration from a median baseline of 40.2mg/dL (32.5,71) by 15% (-19.4,3.6) though without significance (p=0.3).

CONCLUSIONS

Mipomersen reduces LDL-cholesterol (significantly) and Lp(a) (non-significantly) in patients on maximal lipid-lowering drug therapy and regular apheresis, but is often associated with side effects.

Increased Contractile Response to Noradrenaline Induced By Factors Associated with the Metabolic Syndrome in Cultured Small Mesenteric Arteries

This study investigated the effect of the metabolic syndrome associated risk factors hyperglycemia (glucose [Glc]), hyperinsulinemia (insulin [Ins]) and low-grade inflammation (tumor necrosis factor α [TNFα]) on the vasomotor responses of resistance arteries. Isolated small mesenteric arteries from 3-month-old Sprague-Dawley rats, were suspended for 21-23 h in tissue cultures containing either elevated Glc (30 mmol/l), Ins (100 nmol/l), TNFα (100 ng/ml) or combinations thereof. After incubation, the vascular response to noradrenaline (NA), phenylephrine, isoprenaline and NA in the presence of propranolol (10 µmol/l) was measured by wire myography.

RESULTS

Arteries exposed only to combinations of the risk factors showed a significant 1.6-fold increase in the contractile NA sensitivity, which suggests that complex combinations of metabolic risk factors might lead to changes in vascular tone.

Association of coronary artery ectasia with plasma insulin levels in Japanese men of heterozygous familial hypercholesterolemia with the low-density lipoprotein receptor gene mutation K790X

BACKGROUND

Hyperinsulinemia is widely believed to be an important coronary risk factor. We investigated the effect of plasma insulin levels on the development of coronary ectasia in Japanese men with heterozygous familial hypercholesterolemia (FH).

METHODS

A cross-sectional study was conducted in 20 FH men with the LDL receptor mutation (K790X) [age 42.3+/-2.8 years old, body mass index (BMI) 24.6+/-0.7 kg/m2, total cholesterol (TC) 8.68+/-0.36 mmol/l, triglycerides (TG) 1.76+/-0.23 mmol/l, high-density lipoprotein cholesterol (HDL-C) 0.977+/-0.065 mmol/l]. Subjects with diabetes mellitus were excluded. Plasma insulin levels, either fasting or during oral glucose tolerance test, were compared between subjects with and without coronary artery ectasia.

RESULTS

FH subjects with coronary ectasia had significantly higher fasting plasma insulin levels than those without (12.6+/-1.4 vs. 7.7+/-0.5 mU/l; p<0.05). Also, plasma insulin levels during oral glucose tolerance test tended to be higher in the former than in the latter.

CONCLUSIONS

Plasma insulin level could be an important determinant of the development of coronary artery ectasia in Japanese heterozygous FH men.

Decreased serum adiponectin in adolescents and young adults with familial primary hypercholesterolemia

Decreased serum adiponectin is associated with dyslipidemia. However, serum adiponectin status has never before been studied in patients with familial-related severe primary hypercholesterolemia (FRSPH). The aim of this study is to measure serum adiponectin level in a group of young patients with FRSPH and determine its correlation with insulin-resistant status. Twenty-three patients with FRSPH [average LDL-cholesterol (LDL-C) = 250.8 (190-610) mg/dL] without clinical manifestations of metabolic syndrome as well as 46 healthy (control) adolescents and young adults (<30 yr old) were included. The serum adiponectin, fasting sugar, insulin, lipids, systolic and diastolic blood pressure (SBP and DBP), and anthropometrical indices such as body mass index and waist circumference were obtained. The homeostasis model assessment (HOMA) was calculated to estimate the insulin resistant status. Compared with healthy controls, patients with FRSPH had a significantly lower mean serum adiponectin level (7.7+/-1.8 microg/mL vs. 10.1+/-4.3 microg/mL, P= 0.013). After adjustment for HOMA and associated covariates, multiple linear regression analysis showed that patients with FRSPH are significantly associated with hypoadiponectinemia. Compared with healthy controls, patients with FRSPH had a significantly lower mean serum adiponectin level (7.7 +/-1.8 microg/mL vs. 10.1+/-4.3 microg/mL, P = 0.013). After adjustment for HOMA and associated covariates, multiple linear regression analysis showed that patients with FRSPH are significantly associated with hypoadiponectinemia. The serum adiponectin levels are lower in young patients with FRSPH without clinical manifestations of metabolic syndrome. The mechanism of hypoadiponectinemia in patients with FRSPH is probably independent of insulin resistance.

Postchallenge hyperglycemia but not hyperinsulinemia is associated with angiographically documented coronary atherosclerosis in Korean subjects

Although hyperinsulinemia has attracted considerable attention as a possible risk factor for coronary artery disease (CAD), previous studies have not shown consistent results. Hyperglycemia could be an alternative explanation for the association between type 2 diabetes and atherosclerosis. Since previous studies have been mostly lacking coronary angiographic data, we analyzed the relationship between the presence and severity of coronary atherosclerosis based on angiography and hyperinsulinemia or hyperglycemia. Two hundred and thirty subjects underwent coronary angiography and a 75-g oral glucose tolerance test. Age, sex, waist-to-hip ratio, postchallenge 1-h and 2-h glucose levels, plasma triglyceride and HDL-cholesterol levels were different between those with or without CAD. However, there was no significant difference in the plasma insulin levels, area of insulin under the curve, and the ratio of the insulin- and glucose areas between the groups with and without CAD. Multiple logistic regression analysis including fasting-, 1-h, and 2-h glucose values and a variety of atherosclerosis risk factors showed that age, sex and postchallenge 2-h glucose levels were independent determinants of the presence of CAD. These results suggest that coronary atherosclerosis might be associated with postchallenge hyperglycemia, but not with hyperinsulinemia in Korean subjects.

Gene expression profile in skeletal muscle of type 2 diabetes and the effect of insulin treatment

Type 2 diabetes is characterized by muscle insulin resistance. Nondiabetic first-degree relatives of type 2 diabetic patients have also been reported to have insulin resistance. A polygenic basis for pathogenesis of type 2 diabetes has been proposed. A gene expression profile was evaluated in the skeletal muscle of patients with type 2 diabetes while not on treatment for 2 weeks and after 10 days of intensive insulin treatment. Comparison of gene expression pattern with age-, sex-, and BMI-matched people with no family history of diabetes was performed using a microarray technique (Hu6800 arrays; Affymetrix, Santa Clara, CA). Only those gene transcripts showing > or =1.9-fold changes and an average difference in fluorescence intensity of > or =1,000 in all subjects are reported. Insulin sensitivity (SI) was measured using an intravenous glucose tolerance test. Of 6,451 genes surveyed, transcriptional patterns of 85 genes showed alterations in the diabetic patients after withdrawal of treatment, when compared with patterns in the nondiabetic control subjects. Insulin treatment reduced the difference in patterns between diabetic and nondiabetic control subjects (improved) in all but 11 gene transcripts, which included genes involved in structural and contractile functions, growth and tissue development, stress response, and energy metabolism. These improved transcripts included genes involved in insulin signaling, transcription factors, and mitochondrial maintenance. However, insulin treatment altered the transcription of 29 additional genes involved in signal transduction; structural and contractile functions; growth and tissue development; and protein, fat, and energy metabolism. Type 2 diabetic patients had elevated circulating insulin during the insulin-treated phase, although their blood glucose levels (98.8 +/- 6.4 vs. 90.0 +/- 2.9 mg/dl for diabetic vs. control) were similar to those of the control subjects. In contrast, after withdrawal of treatment, the diabetic patients had reduced SI and elevated blood glucose (224.0 +/- 26.2 mg/dl), although their insulin levels were similar to those of the nondiabetic control subjects. This study identified several candidate genes for muscle insulin resistance, complications associated with poor glycemic control, and effects of insulin treatment in people with type 2 diabetes.