Small-dense LDL cholesterol/large-buoyant LDL cholesterol ratio as an excellent marker for indicating lipodystrophy in HIV-infected patients

The small dense LDL particle/large buoyant LDL particle ratio is associated with glucose metabolic status in pregnancy

BACKGROUND

The lipoprotein subfraction particle profile can be used to improve clinical assessments of cardiovascular disease risk and contribute to early detection of atherogenic dyslipidemia. Lipid alterations in gestational diabetes have been extensively studied, but the results have been inconsistent. Here, we investigated serum lipoprotein subfraction particle levels and their association with glucose metabolic status in pregnancy.

METHODS

Twenty-eight pregnant women with gestational diabetes and 56 pregnant women with normal glucose tolerance matched for body mass index were enrolled in this study. We assessed fasting serum lipid concentrations and lipoprotein subfraction particle levels in participants between 24 and 28 weeks of gestation.

RESULTS

The level of low-density lipoprotein (LDL) cholesterol was significantly lower in women with gestational diabetes than in those with normal glucose tolerance, but the triglyceride and high-density lipoprotein (HDL) cholesterol levels of the two groups were similar. Lipoprotein particle analysis showed that very-low-density lipoprotein (VLDL) particle number and the small dense LDL particle/large buoyant LDL particle (sdLDL-P/lbLDL-P) ratio were significantly higher in women with gestational diabetes than in those with normal glucose tolerance (P = 0.013 and P = 0.015, respectively). In multivariate analysis, fasting glucose was independently and positively associated with sdLDL-P/lbLDL-P ratio even after adjustment for maternal age, gestational weight gain, BMI and LDL cholesterol (standardized Beta = 0.214, P = 0.029).

CONCLUSIONS

The sdLDL-P/lbLDL-P ratio is higher in GDM compared with non-diabetic pregnant women, and positively and independently associated with fasting glucose in pregnant women.

Lipid levels in HIV-positive men receiving anti-retroviral therapy are not associated with copy number variation of reverse cholesterol transport pathway genes

BACKGROUND

The exacerbation of HIV-1 associated dyslipidemia seen in a subset of patients receiving anti-retroviral therapy suggests that genetic factors put these individuals at greater risk of cardiovascular disease. Single nucleotide polymorphisms (SNPs) within genes of and influencing the reverse cholesterol transport (RCT) pathway are associated with lipid levels but little is known regarding their copy number variation (CNV). This form of quantitative genetic variation has the potential to alter the amount of gene product made, thereby also influencing lipid metabolism.

RESULTS

To examine if CNV in RCT pathway genes was associated with altered serum lipid profiles in HIV-positive individuals receiving therapy, we designed a custom multiplex ligation-dependent probe amplification assay to screen 16 RCT genes within a subset of individuals from the Multicenter AIDS Cohort Study who show extreme lipid phenotypes. Verification of CNV was performed using a custom NanoString assay, and the Illumina HT-12 mRNA expression microarray was used to determine the influence of copy number on gene expression. Among the RCT genes, CNV was observed to be extremely rare. The only CNV seen was in the CETP gene, which showed a loss of copy in 1 of the 320 samples (0.3%) in our study. The genes in our study showed little variation in expression between individuals, and the variation seen was not related to any detected CNV.

CONCLUSIONS

Whole gene CNV is uncommon in RCT pathway genes, and not a major factor in the development of highly active antiretroviral therapy (HAART) associated dyslipidemia.

Small-dense LDL/large-buoyant LDL ratio associates with the metabolic syndrome

OBJECTIVE

Heterogeneous particles of intermediate-density lipoprotein (IDL) and low-density lipoprotein (LDL) vary in atherogenesis. We investigated the association between the metabolic syndrome (MetS) score and lipoprotein subclasses.

DESIGN AND METHODS

A total of 260 outpatients were scored into six groups, based on their number of MetS components. Lipoprotein subclass determined by polyacrylamide tube gel electrophoresis separates IDL particles into three midbands (MID-A to C) and LDL into larger-buoyant (LDL1 and LDL2) and small-dense LDL (LDL3 to LDL6).

RESULTS

Mean concentrations of VLDL, MIDC, LDL2, and LDL3 to LDL6 positively correlated with increasing MetS score, but those of MIDA, LDL1 and HDL-C inversely correlated. LDL2 and LDL3 to LDL6 increased while MIDA and LDL1 decreased with increasing visceral fat, HOMA-IR, and triglycerides, with a reverse pattern for HDL-C. MIDB and MIDC were unchanged. By logistic regression, LDL1 and LDL3 to LDL6 significantly associates with the MetS score (odds ratio=0.957 and 1.077, respectively). The ratio of (LDL3 to LDL6)/LDL1 in the presence of HDL-C, showed the strongest association with MetS.

CONCLUSIONS

Respective subpopulations of IDL and LDL particles can vary in their ability to identify MetS. Because of the most strongly associated with MetS, (LDL3 to LDL6)/LDL1 ratio is proposed as an excellent marker for evaluating lipid metabolic status in patient with MetS.

Polymorphisms of the ApoE (Apolipoprotein E) gene and their influence on dyslipidemia in HIV-1-infected individuals

The purpose of this retrospective case-control study was to investigate the frequency of Apolipoprotein E (ApoE) polymorphisms and their influence on antiretroviral therapy (ART)-induced lipodystrophy or dyslipidemia in HIV-infected Thai patients. The clinical characteristics and frequencies of ApoE genotypes were compared between the case (moderate to severe lipodystrophy, n = 67) and control (absent to mild lipodystrophy, n = 18) groups. The ApoE genotype frequencies among the 85 participants were 2.35% (n = 2) for E2/E2, 20% (n = 17) for E2/E3, 9.41% (n = 8) for E2/E4, 36.47% (n = 31) for E3/E3, 30.59% (n = 26) for E3/E4, and 1.18% (n = 1) for E4/E4. None of the ApoE genotypes showed association with ART-induced lipodystrophy. However, the levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-cholesterol), and ApoB were lower in patients carrying the E2 allele but higher in E4 carriers. Interestingly, the ratios between TC and high-density lipoprotein (TC/HDL cholesterol ratio) and ApoB/ApoA-I ratio were significantly higher in the case group. Patients carrying the E2 allele displayed protective lipid profile, while those carrying E4 appeared to be at higher risk of dyslipidemia. In conclusion, ApoE polymorphisms were not associated with lipodystrophy in patients undergoing antiretroviral therapy but influenced lipid alteration.