Apo(a) phenotyping and long-term prognosis for coronary artery disease

The rs10455872-G allele of the LPA gene is associated with high lipoprotein(a) levels and increased aortic valve calcium in a Mexican adult population

Polymorphisms in the LPA gene have been associated with aortic valve calcification (AVC). There are wide differences in the allelic frequencies, Lp(a) levels, and the association with AVC among ethnic groups. The aim of this study was to determine the association of the LPA gene polymorphisms with Lp(a) levels and risk of developing AVC, in Mexican-Mestizos population. Six LPA polymorphisms (rs10455872, rs7765803, rs6907156, rs1321195, rs12212807 and rs6919346) were genotyped by TaqMan assays in 1,265 individuals without premature coronary artery disease. The presence of AVC was determined by computed tomography. The association of the LPA polymorphisms with AVC, Lp(a), and other cardiovascular risk factors (CVRF) was evaluated using logistic regression analysis. Compared to AA genotype, subjects with AG+GG genotypes had high prevalence of Lp(a) ≥ 30 mg/dL (7.1% vs. 23.7%, p<0.001) and AVC (19.0% vs. 29.4%, p=0.007). In a model adjusted for several CVRF, the LPA rs10455872-G allele was associated with high Lp(a) levels and AVC. Carriers of G allele had a high risk of Lp(a) ≥ 30 mg/dL (OR= 3.86, CI 95%: 2.2 - 6.7, p=0.001) and AVC (OR= 2.54, CI 95%: 1.56 - 4.14, p=0.001), independently of other CVRF. In this population, carriers of rs10455872-G allele had 3.86 and 2.54 higher risk of Lp(a) ≥ 30 mg/dL or presence of AVC, respectively.

Effects of folic acid supplementation on serum homocysteine and lipoprotein (a) levels during pregnancy

Introduction:There are many ideas concerning the etiology and pathogenesis of preeclampsia including endothelial dysfunction, inflammation and angiogenesis. Elevated levels of total homocysteine (Hcy) and lipoprotein (a) [Lp(a)] are risk factors for endothelial dysfunction. This study aimed to evaluate the effect of high dose folic acid (FA) on serum Hcy and Lp(a) concentrations with respect to methylenetetrahydrofolate reductase (MTHFR) polymorphisms 677C→T during pregnancy.

Methods: In a prospective uncontrolled intervention, 90 pregnant women received 5 mg FA supplementation before pregnancy till 36th week of pregnancy. The MTHFR polymorphisms 677C→T, serum lactate dehydrogenase activity, urine protein and creatinine concentrations were measured before starting folic acid administration. Serum levels of Hcy and Lp(a) were determined before and after completion of folic acid supplementation period.

Results: Supplementation of the patients with FA for 36 week decreased the median (minimum– maximum) levels of serum Hcy from 11.40 μmol/L (4.40-28.70) to 9.70 (1.60-20.80) μmol/L (p=0.001). There was no significant change in serum Lp(a) after FA supplementation (p=0.17). The overall prevalence of genotypes in pregnant women that were under study for MTHFR C677T polymorphism was 53.3% CC, 26.7% CT and 20.0% TT. There was no correlation between decreasing level of serum Hcy in the patients receiving FA and MTHFR polymorphisms.

Conclusion:Although FA supplementation decreased serum levels of Hcy in different MTHFR genotypes, serum Lp(a) was not changed by FA supplements. Our data suggests that FA supplementation effects on serum Hcy is MTHFR genotype independent in pregnant women.

Lipoprotein (a) as a risk factor for ischemic stroke: a meta-analysis

OBJECTIVE

Lipoprotein (a) [Lp(a)] harbors atherogenic potential but its role as a risk factor for ischemic stroke remains controversial. We conducted a meta-analysis to determine the relative strength of the association between Lp(a) and ischemic stroke and identify potential subgroup-specific risk differences.

METHODS

A systematic search using the MeSH terms "lipoproteins" OR "lipoprotein a" AND "stroke" was performed in PubMed and ScienceDirect for case-control studies from June 2006 and prospective cohort studies from April 2009 until December 20th 2014. Data from eligible papers published before these dates were reviewed and extracted from previous meta-analyses. Studies that assessed the relationship between Lp(a) levels and ischemic stroke and reported generic data-i.e. odds ratio [OR], hazard ratio, or risk ratio [RR]-were eligible for inclusion. Studies that not distinguish between ischemic and hemorrhagic stroke and transient ischemic attack were excluded. Random effects meta-analyses with mixed-effects meta-regression were performed by pooling adjusted OR or RR.

RESULTS

A total of 20 articles comprising 90,904 subjects and 5029 stroke events were eligible for the meta-analysis. Comparing high with low Lp(a) levels, the pooled estimated OR was 1.41 (95% CI, 1.26-1.57) for case-control studies (n = 11) and the pooled estimated RR was 1.29 (95% CI, 1.06-1.58) for prospective studies (n = 9). Sex-specific differences in RR were inconsistent between case-control and prospective studies. Study populations with a mean age of ≤55 years had an increased RR compared to older study populations. Reported Lp(a) contrast levels and ischemic stroke subtype significantly contributed to the heterogeneity observed in the analyses.

CONCLUSION

Elevated Lp(a) is an independent risk factor for ischemic stroke and may be especially relevant for young stroke patients. Sex-specific risk differences remain conflicting. Further studies in these subgroups may be warranted.

Low-molecular-weight lipoprotein (a) and low relative lymphocyte concentration are significant and independent risk factors for coronary heart disease in patients with type 2 diabetes mellitus: Lp(a) phenotype, lymphocyte, and coronary heart disease

Background

The aim of the present prospective study was to examine whether lipoprotein (a) [Lp(a)] phenotypes and/or low relative lymphocyte concentration (LRLC) are independently associated with coronary heart disease (CHD) in patients with type 2 diabetes mellitus (T2DM).

Methods

Serum Lp(a) concentration, Lp(a) phenotypes, and RLC were analyzed in 214 subjects. Lp(a) phenotypes were classified into 7 subtypes according to sodium dodecyl sulfate-agarose gel electrophoresis by Western blotting. Subjects were assigned to the low-molecular-weight (LMW (number of KIV repeats: 11–22) ) and high-molecular-weight (HMW( number of KIV repeats: >22 )) Lp(a) groups according to Lp(a) phenotype and to the LRLC (RLC: <20.3%) and normal RLC (NRLC; RLC: ≥20.3%) groups according to RLC. A CHD event was defined as the occurrence of angina pectoris or myocardial infarction during the follow-up period.

Results

During the follow-up period, 30 cases of CHD events were verified. Neutrophil count showed no correlation with CHD, while relative neutrophil concentration and RLC showed positive and negative correlations, respectively, with CHD. The Cox proportional hazard model analysis revealed the following hazard ratios adjusted for LMW Lp(a), LRLC, and LMW Lp(a) + LRLC: (4.31; 95% confidence interval [CI], 1.99-9.32; P < 0.01, 3.621; 95% CI, 1.50-8.75; P < 0.05, and 7.15; 95% CI, 2.17-23.56; P < 0.01, respectively).

Conclusions

Our results suggest that both LMW Lp(a) and LRLC are significant and independent risk factors for CHD and that the combination thereof more strongly predicts CHD in patients with T2DM.

Age-related modification of antioxidant enzyme activities in relation to cardiovascular risk factors

BACKGROUND

Since oxidative stress might cause and promote cardiovascular risk factors such as oxidized low-density lipoproteins (oxLDL), apolipoprotein(a) [apo(a)], asymmetric dimethylarginine (ADMA) and fetuin A, we investigated antioxidant enzyme activities in relation to the vascular redox balance and these risk factors in elderly people.

MATERIALS AND METHODS

For this observational study, a total of 102 subjects were recruited and divided into three groups: A (70-74 years/n = 48), B (75-79 years/n = 35) and C (≥ 80 years/n = 19). Activities of the erythrocyte antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) were determined photometrically oxLDL, apo(a), ADMA and fetuin A by ELISA. Plasma concentrations of the lipid peroxidation products malondialdehyde (MDA) and conjugated dienes (CD) were analysed with HPLC.

RESULTS

There were no significant age-associated alterations in apo(a) levels, but there was a significant age-related decrease in activities of SOD (A>C, B>C: P < 0·01), CAT (A>C: P < 0·05) and GSH-Px (A>C: P < 0·05), accompanied by a significant increase in oxLDL (A<C: P < 0·001; B<C: P < 0·05), ADMA (A<B: P < 0·05; A<C: P < 0·001), MDA (A<C, B<C: P < 0·01) and CD (A<C, B<C: P < 0·01), and a significant decrease in fetuin A (A>C: P < 0·01; B>C: P < 0·05). Consequently, all groups showed significant negative age-associated correlations between CAT and MDA (A, B, C: P < 0·05), GSH-Px and CD (A, C: P < 0·01; B: P < 0·05), SOD and oxLDL (A, B: P < 0·05; C: P < 0·01), and fetuin A and MDA (A: P < 0·01; B, C: P < 0·05), and a significant positive correlation between oxLDL and ADMA (A, B: P < 0·05; C: P < 0·01).

CONCLUSIONS

This study indicates a significant age-related decrease in antioxidant enzyme activities accompanied by significantly increased systemic oxidative stress, which promotes the cardiovascular risk factors oxLDL, ADMA and fetuin A in elderly people.