Abstract-Human paraoxonase (PON1) is a calcium-dependent esterase closely associated with high density lipoprotein (HDL)-containing apolipoprotein AI (apoAI), which has been shown to confer antioxidant properties to HDL. PON1 has been recently implicated in the pathogenesis of atherosclerosis. Low PON1 activities have been found in familial hypercholesterolemia (FH) and diabetes mellitus. We have undertaken a study of the effect of the lipid-lowering drug simvastatin on serum PON1 activity (in relation to paraoxon and arylesterase activity), on apoAI-containing and apolipoprotein B (apoB)-containing lipoproteins, and on lipid peroxide concentrations in 64 (39 women and 25 men) unrelated FH patients. We have also analyzed the influence of the PON1-192 and PON1-55 genetic polymorphisms on the response of PON1 activity to simvastatin therapy. A venous blood sample for a baseline analysis and another after 4 months of simvastatin therapy at a dosage of 20 mg per day were taken. The major effect of simvastatin on lipid traits was to decrease serum cholesterol, low density lipoprotein (LDL) cholesterol, and lipid peroxide concentrations by 19.9%, 26.3%, and 37.3%, respectively. There was also a significant decrease in serum apoB, LDL apoB, and triglyceride concentrations (20.5%, 21.1%, and 15.6%, respectively). Conversely, simvastatin had no significant influence on very low density lipoprotein-lipid content, HDL cholesterol, apoAI concentrations, and lipoprotein AI and AI:AII particles. Remarkably, serum PON1 activity toward paraoxon significantly increased during treatment with simvastatin (168.7Ϯ100.3 U/L before therapy versus 189.5Ϯ116.5 U/L after therapy, Pϭ0.005). Arylesterase activity displayed only a nonsignificant trend to increase after therapy. Whereas PON1 activity levels were significantly lower in FH patients before simvastatin therapy compared with those of 124 normolipidemic subjects (168.7Ϯ100.3 versus 207.6Ϯ125.2 U/L, respectively; PϽ0.05), this difference disappeared after simvastatin therapy. After simvastatin therapy, a significantly negative correlation between PON1 activity and lipid peroxide concentration was observed (rϭϪ0.35, Pϭ0.028). The latter also strongly correlated with LDL cholesterol concentration (rϭ0.64, PϽ0.001). Serum PON1 activity levels were significantly lower in the low-activity PON1-192 QQ and PON1-55 M carriers than in R carriers and in LL carriers, respectively. No significant differences were found in the therapeutic response of PON1 activity between genotype groups (8.5% and 11.1% increase for QQ homozygous and R-carrier FH patients, respectively, and 12.7% and 9.5% increase for LL homozygotes and M carriers, respectively). We conclude that simvastatin may have important antioxidant properties through increasing serum PON1 activity, perhaps as a consequence of reducing oxidative stress, by a mechanism independent of apoAI-containing lipoprotein concentration and without the influence of PON1-192 and PON1-55 genetic polymorphisms. Further studies are clearly warranted to c...

Nonstandard abbreviations used: large conductance, Ca 2+ -dependent K + (BK); conductance (G); diastolic blood pressure (DBP); odds ratio (OR); open probability (PO).

Obesity is associated with increased risk of several diseases and has become epidemic. Obesity is highly heritable but the genetic variants identified by genome-wide association studies explain only limited variability. Epigenetics could contribute to explain the missing variability. The study aim was to discover differential methylation patterns related to obesity. We designed an epigenome-wide association study with a discovery phase in a subsample of 641 REGICOR study participants, validated by analysis of 2,515 participants in the Framingham Offspring Study. Blood DNA methylation was assessed using Illumina HumanMethylation450 BeadChip. Next, we meta-analyzed the data using the fixed effects method and performed a functional and pathway analysis using the Ingenuity Pathway Analysis software. We were able to validate 94 CpGs associated with body mass index (BMI) and 49 CpGs associated with waist circumference, located in 95 loci. In addition, we newly discovered 70 CpGs associated with BMI and 33 CpGs related to waist circumference. These CpGs explained 25.94% and 29.22% of the variability of BMI and waist circumference, respectively, in the REGICOR sample. We also evaluated 65 of the 95 validated loci in the GIANT genome-wide association data; 10 of them had Tag SNPs associated with BMI. The top-ranked diseases and functions identified in the functional and pathway analysis were neurologic, psychological, endocrine, and metabolic.

Paraoxonase (PON1) is an antioxidant enzyme closely associated with high-density lipoproteins. Low PON1 has been shown in oxidative stress-associated processes such as dyslipidemia, diabetes mellitus, advancing age, and smoking. Indeed, oxidative stress is related to the degree of insulin resistance, a key component of the metabolic syndrome. Therefore, the possible relationship between PON1 activity and the metabolic syndrome was investigated. From 1364 randomly recruited subjects, 285 were found to have the metabolic syndrome, according to the guidelines published by the National Cholesterol Education Program, Adult Treatment Panel III. PON1 activity, lipid peroxides, and PON1 codon 192 genotypes, which strongly modulate PON1 activity, were determined. Serum PON1 activity levels were found to be significantly lower, and lipid peroxide concentrations significantly higher, in subjects with the metabolic syndrome compared with unaffected subjects (P = 0.033 and < 0.001, respectively). Study subjects showed a significant decreasing trend in PON1 activity levels and a significant increasing trend in lipid peroxide concentrations, with the increase in the number of metabolic disturbances. No differences in the prevalence of PON1 codon 192 genotypes were found among the categories of metabolic abnormalities. In conclusion, a greater degree of severity of the metabolic syndrome is associated with a progressively worse antioxidant/oxidant balance, which is consistent with increased oxidative stress and lower antioxidant PON1 enzymatic capacity.

Lipid traits (total, low-density and high-density lipoprotein cholesterol, and triglycerides) are risk factors for cardiovascular disease. DNA methylation is not only an inherited but also modifiable epigenetic mark that has been related to cardiovascular risk factors. Our aim was to identify loci showing differential DNA methylation related to serum lipid levels. Blood DNA methylation was assessed using the Illumina Human Methylation 450 BeadChip. A two-stage epigenome-wide association study was performed, with a discovery sample in the REGICOR study (n = 645) and validation in the Framingham Offspring Study (n = 2,542). Fourteen CpG sites located in nine genes (SREBF1, SREBF2, PHOSPHO1, SYNGAP1, ABCG1, CPT1A, MYLIP, TXNIP and SLC7A11) and 2 intergenic regions showed differential methylation in association with lipid traits. Six of these genes and 1 intergenic region were new discoveries showing differential methylation related to total cholesterol (SREBF2), HDL-cholesterol (PHOSPHO1, SYNGAP1 and an intergenic region in chromosome 2) and triglycerides (MYLIP, TXNIP and SLC7A11). These CpGs explained 0.7%, 9.5% and 18.9% of the variability of total cholesterol, HDL cholesterol and triglycerides in the Framingham Offspring Study, respectively. The expression of the genes SREBF2 and SREBF1 was inversely associated with methylation of their corresponding CpGs (P-value = 0.0042 and 0.0045, respectively) in participants of the GOLDN study (n = 98). In turn, SREBF1 expression was directly associated with HDL cholesterol (P-value = 0.0429). Genetic variants in SREBF1, PHOSPHO1, ABCG1 and CPT1A were also associated with lipid profile. Further research is warranted to functionally validate these new loci and assess the causality of new and established associations between these differentially methylated loci and lipid metabolism.