Differential low density lipoprotein hydrated density distribution in female and male patients with familial hypercholesterolemia

Mipomersen preferentially reduces small low-density lipoprotein particle number in patients with hypercholesterolemia

BACKGROUND

Because of variability in lipoprotein cholesterol content, low-density lipoprotein (LDL) cholesterol frequently underrepresents or overrepresents the number of LDL particles. Mipomersen is an antisense oligonucleotide that reduces hepatic production of apolipoprotein B-100, the sole apolipoprotein of LDL.

OBJECTIVE

To characterize the effects of mipomersen on lipoprotein particle numbers as well as subclass distribution using nuclear magnetic resonance (NMR) spectroscopy.

METHODS

We compared the tertiary results for the direct measurement of LDL particle numbers by NMR among 4 placebo-controlled, phase 3 studies of mipomersen that had similar study designs but different patient populations: homozygous familial hypercholesterolemia (HoFH), severe hypercholesterolemia, heterozygous familial hypercholesterolemia with established coronary artery disease, or hypercholesterolemia with high risk for coronary heart disease (HC-CHD).

RESULTS

HoFH patients had the highest median total LDL particles at baseline compared with HC-CHD patients, who had the lowest. At baseline, the HoFH population uniquely had a greater mean percentage of large LDL particles (placebo, 60.2%; mipomersen, 54.9%) compared with small LDL particles (placebo, 33.1%; mipomersen, 38.9%). In all 4 studies, mipomersen was associated with greater reductions from baseline in the concentrations of small LDL particles compared with those of large LDL particles, and both total LDL particles and small LDL particles were statistically significantly reduced.

CONCLUSIONS

Mipomersen consistently reduced all LDL particle numbers and preferentially reduced the concentration of small LDL particles in all 4 phase 3 studies.

Quantity versus quality of LDL cholesterol in patients with familial hypercholesterolemia--which is more important?

BACKGROUND

The aim of this study was to determine the effects of low-density lipoprotein (LDL) particle size and composition on the susceptibility of LDL to oxidation in subjects with Familial Hypercholesterolemia (FH).

METHODS

LDL was isolated from 20 FH homozygotes, 20 FH heterozygotes and 20 normal controls. Susceptibility of LDL to ex vivo copper-mediated oxidation was assessed by measuring conjugated diene production at 234 nm. Other factors known to influence LDL oxidation, namely particle size, vitamin E levels, and fatty acid composition of the LDL particles were also measured.

RESULTS

The mean duration of the lag phase was 1.42-fold longer in the FH homozygotes, and 1.21-fold longer in the FH heterozygotes than in the normal controls. LDL particle size was significantly larger in the FH homozygotes (26.45+/-0.37 nm) and FH heterozygotes (26.01+/-0.40 nm) compared to the normal control group (25.17+/-0.39 nm). LDL vitamin E concentrations, when expressed relative to LDL cholesterol concentrations, were similar in all the groups. In addition, no significant differences were observed in the total saturated, monounsaturated or polyunsaturated fatty acid content of LDL in the three groups of subjects.

CONCLUSION

These results suggest that it is the great excess in LDL quantity, rather than LDL 'quality', that is responsible for the severe and premature atherosclerosis in patients with FH.

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

OBJECTIVE

To study the relationship between hyperinsulinaemia, insulin resistance, leptin and atherosclerosis in subjects with familial hypercholesterolaemia (FH).

DESIGN

Case-control cross-sectional study.

SETTING

Lipid clinic, Johannesburg Hospital, South Africa.

SUBJECTS AND METHODS

Fasting serum lipid, glucose, insulin and leptin levels were measured in 24 homozygous FH subjects; 20 FH heterozygotes without coronary artery disease (CAD); 22 heterozygotes with documented CAD; and 20 healthy normocholesterolaemic subjects. Insulin resistance was calculated using the homeostasis model assessment (HOMA) formula.

RESULTS

Mean glucose and insulin levels were similar in all 4 groups. There was no significant difference in calculated insulin resistance between any of the groups. There was also no relationship between the degree of insulin resistance and total or LDL-cholesterol levels. Using Spearman's correlation coefficient (Rs) calculated insulin resistance correlated with triglyceride (Rs = 0.27; P<0.05) and inversely with HDL-cholesterol (Rs = -0.26; P<0.05). Fasting insulin concentrations and calculated insulin resistance were similar in FH subjects with overt CAD compared to those without. Leptin levels were higher in the FH subjects with CAD. However, these subjects were older and had a larger body mass index (BMI), and when adjusted for age and BMI, only BMI correlated with leptin levels (multiple r = 0.65; P<0.001).

CONCLUSIONS

In the absence of other causes of insulin resistance, FH subjects have normal fasting insulin levels and, in general, they are not insulin resistant. Insulin resistance appears to play little role in the pathogenesis of accelerated atherosclerosis in FH.

Low-density lipoprotein cholesterol bulk is the pivotal determinant of atherosclerosis in familial hypercholesterolemia

This study's aim was to determine whether biochemical risk factors such as lipoprotein(a), fibrinogen, homocysteine, and insulin, as well as low-density lipoprotein (LDL) particle size, were predictive of carotid intimamedia thickness (IMT), an early marker of atherosclerosis, in subjects with familial hypercholesterolemia (FH). We also determined whether plasma 8-isoprostane, as a marker of in vivo lipid oxidation, correlated with carotid IMT. Twenty-two homozygous and 20 heterozygous subjects with FH were compared with 20 normocholesterolemic controls. On univariate analysis, plasma total and LDL cholesterol, the cholesterol-years score (CYS), lipoprotein(a), and fibrinogen, but not homocysteine or insulin, were positively related, and high-density lipoprotein (HDL) cholesterol was negatively related to carotid IMT. However, on multivariate analysis, only LDL cholesterol and the CYS predicted carotid IMT (multiple r = 0.82; r2 = 0.68; p <0.0001). The subjects with FH had large rather than small dense LDL particles, and plasma 8-isoprostane levels were not increased. LDL cholesterol and the CYS, or "cholesterol bulk" are the pivotal determinants of atherosclerosis and are the strongest predictors of carotid IMT in FH.