Influence of ghrelin gene polymorphisms on hypertension and atherosclerotic disease.

Ghrelin is involved in several metabolic and cardiovascular processes. Recent evidence suggests its involvement in blood pressure regulation and hypertension. The aim of the study was to determine associations of single-nucleotide polymorphisms (SNPs) and haplotypes of the ghrelin gene (GHRL) with hypertension and atherosclerotic disease. Six GHRL SNPs (rs27647, rs26802, rs34911341, rs696217, rs4684677 and a -473G/A (with no assigned rsID)) were investigated in a sample of 1143 hypertensive subjects and 1489 controls of Caucasian origin. Both single-locus and haplotype association analyses were performed. In single-locus analyses, only the non-synonymous rs34911341 was associated with hypertension (odds ratio (OR)=1.95 (95% confidence interval (CI): 1.26-3.02), P=0.003). Six common haplotypes with frequency >1% were inferred from the studied GHRL SNPs, and their frequency distribution was significantly different between hypertensive subjects and controls (chi(2)=12.96 with 5 d.f. (degree of freedom), P=0.024). The effect of rs26802 was found to be significantly (P=0.017) modulated by other GHRL SNPs, as its C allele conferred either an increased risk (OR=1.30 (1.08-1.57), P=0.005) or a decreased risk (OR=0.50 (0.23-1.06), P=0.07) of hypertension according to the two different haplotypes on which it can be found. No association of GHRL SNPs or haplotypes with atherosclerotic disease was observed. In conclusion, we observed statistical evidence for association between GHRL SNPs and risk of hypertension.

The Leu72Met polymorphism of the ghrelin gene is associated with a decreased risk for type 2 diabetes.

BACKGROUND: Ghrelin is involved in several metabolic and cardiovascular processes. The Leu72Met polymorphism of its gene was associated with an increased risk of type 2 diabetes (DM2) in some, but not all studies. Its association with atherosclerosis is not known. METHODS: We investigated 420 Caucasian subjects with DM2 and 430 controls without diabetes (56.6% male, age 62+/-10 years). RESULTS: The Leu72Leu genotype frequencies were 89.76/84.65%, the Leu72Met 9.52/15.12% and the Met72Met 0.71/0.23% (P=0.029) in the DM2 and controls groups, respectively. In subjects with Met72+ genotypes the risk of DM2 was significantly decreased (univariate OR 0.63, 95% CI 0.42-0.95, P=0.026). In a logistic regression model, body mass index, hypertension and a positive family history for diabetes were predictors of diabetes while the polymorphism remained negatively associated with the disease (OR 0.62, 95% CI 0.40-0.97, P=0.036). After adjusting for known risk factors for atherosclerosis, the Met72+ variant was not associated with atherosclerotic disease (OR 1.41, 95% CI 0.78-2.54, P=0.25). Ghrelin concentrations were not associated with the polymorphism, DM2 or atherosclerotic disease. CONCLUSIONS: The Leu72Met polymorphism of the ghrelin gene is associated with a decreased risk for DM2. There is no association between the variant and atherosclerotic disease or ghrelin concentrations.

Effects of ezetimibe and/or simvastatin on LDL receptor protein expression and on LDL receptor and HMG-CoA reductase gene expression: a randomized trial in healthy men.

OBJECTIVE: The combination of simvastatin, an HMG-CoA reductase inhibitor, and ezetimibe, an inhibitor of Niemann-Pick C1-like 1 protein, decreases cholesterol synthesis and absorption and reduces circulating LDL-cholesterol concentrations. The molecular mechanisms underlying the pronounced lipid-lowering effects of this combination have not been fully elucidated in humans. METHODS AND RESULTS: One center, prospective, randomized, parallel three-group study in 72 healthy men (mean age 32+/-9 years, mean body mass index 25.7+/-3.2 kg/m(2)). Each group of twenty-four subjects received a 14-day treatment with either ezetimibe (10mg/day), simvastatin (40 mg/day) or their combination. Lipid levels, the ratio of non-cholesterol sterols to cholesterol concentrations (used as markers of cholesterol synthesis and absorption), cell surface LDL receptor (LDLR) protein as well as LDLR and HMG-CoA reductase gene expression in mononuclear blood cells were measured at baseline and at the end of the study. LDL-C decreased in all groups. Simvastatin decreased, ezetimibe increased and their combination had no effect on HMG-CoA reductase activity. Simvastatin and the combination of ezetimibe and simvastatin increased the HMG-CoA reductase and LDLR gene expression while ezetimibe had no effect. The cell surface LDLR protein expression remained unchanged in all groups. The combination of ezetimibe and simvastatin increased the expression of the serine protease proprotein convertase subtilisin/kexin 9 (PCSK9), an enzyme shown to down-regulate LDLR protein levels. CONCLUSIONS: The co-administration of ezetimibe and simvastatin abrogates the ezetimibe-induced increase in cholesterol synthesis and up-regulates the LDLR gene but not protein expression, an effect possibly mediated through a parallel upregulation of PCSK9 expression.

The peroxisome proliferator-activated receptor delta +294T/C polymorphism in relation to lipoprotein metabolism in patients with diabetes mellitus type 2 and in non-diabetic controls.

OBJECTIVE: Peroxisome proliferator-activated receptor delta (PPARdelta) is an ubiquitously expressed transcription factor that has been implicated in the regulation of genes related to cholesterol metabolism. Conflicting results exist regarding the association of the recently described +294T/C polymorphism in the 5'-untranslated region (5'-UTR) in exon 4 of the PPARdelta gene and plasma lipoprotein concentrations. Purpose of the present study was to examine for the first time in a German population and for the first time also in women the presence of a potential association between the aforementioned polymorphism and lipoprotein concentrations in patients with diabetes mellitus type 2 (DM-2) and in non-diabetic controls. Furthermore, a possible gene-gene interaction between the PPARdelta +294T/C polymorphism and the PPARalpha L162V polymorphism was examined. DESIGN AND METHODS: We determined by PCR the polymorphism in a total of 402 patients with DM-2 (230 men and 172 women) and in 436 healthy controls (248 men and 188 women) from the LIANCO study (lipid analytic cologne). RESULTS: The genotype distribution was not different between DM-2 and controls (+294TT 65.6% versus 66.7%, +294TC 30.5% versus 29.4%, +294CC 3.9 versus 4.0%, respectively). There was no difference in the low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) or triglyceride (TG) concentrations between carriers and non-carriers of the rare C allele in the DM-2 population. In specific, the heterozygotes for the C allele had LDL-C concentrations of 157+/-80 mg/dl, HDL-C of 54+/-17 mg/dl and TG of 273+/-507 mg/dl, while the C allele homozygotes had concentrations of LDL-C 149+/-44 mg/dl, HDL-C of 59+/-21 mg/dl and TG of 197+/-110 mg/dl. The LDL-C, HDL-C and TG concentrations of TT homozygotes were 156+/-49 mg/dl, 56+/-18 mg/dl and TG 225+/-242 mg/dl, respectively. The same lack of association was present in the non-diabetic controls, both in men and in women. There was no association between the genotypes and body mass index. Furthermore, no gene-gene interaction between the PPARdelta +294TC and the PPARalpha L162V polymorphism was observed regarding lipoprotein concentrations and atherosclerotic disease. CONCLUSIONS: The data suggest that the PPARdelta +294T/C polymorphism has no influence on plasma lipoprotein concentrations, body mass index or atherosclerotic disease either in healthy subjects or in patients with DM-2, both in males and females.

Peroxisome proliferator-activated receptor-gamma2 Pro12Ala and endothelial nitric oxide synthase-4a/b gene polymorphisms are not associated with hypertension in diabetes mellitus type 2.

OBJECTIVE AND DESIGN: The Pro12Ala and the 4a/b polymorphisms of the peroxisome proliferator-activated receptor gamma (PPARgamma) and the endothelial nitric oxide-synthase (eNOS) genes, respectively, have been associated with hypertension in some but not all studies. The purpose of this study was to investigate the association between these polymorphisms and hypertension in patients with diabetes mellitus type 2 (DM2). METHODS: We determined, by polymerase chain reaction (PCR), the Pro12Ala PPARgamma2 and the eNOS 4a/b gene polymorphisms in a total of 395 patients with diabetes mellitus 2 (DM2) (225 men and 170 women) from the LIANCO (Lipid-Analytic-Cologne) study. Hypertension was defined as known or newly diagnosed hypertension according to current national guidelines. Associations were determined using chi-square statistics. The influence of genotype and other parameters on blood pressure was determined by analysis of variance (ANOVA) and multivariate analyses. RESULTS: The genotype frequencies of the Pro12Ala polymorphism were 3% AlaAla, 23% ProAla and 74% ProPro and of the eNOS 4a/b polymorphism 3% a/a, 25% b/a and 72% b/b. There were 65% patients with, and 35% without hypertension. A total of 77% of the patients with hypertension were under pharmacological treatment. The mean systolic and diastolic blood pressure (SBP, DBP) was 148 +/- 22 and 84 +/- 11 mmHg in patients with, and 131 +/- 12 and 79 +/- 8 mmHg in patients without, hypertension. There was no difference in the occurrence of hypertension among ProAla and AlaAla subjects compared with ProPro subjects (P = 0.98). There was also no difference between a-allele carriers and non-carriers of the eNOS polymorphism (P = 0.42). There were no differences between men and women in the associations. Analysis of variance did neither identify an influence on systolic or diastolic blood pressure by the presence of the Ala or the a-allele of the respective genotypes nor a significant interaction of the two. CONCLUSIONS: In DM2 the Pro12Ala and 4a/b gene polymorphisms of the PPARgamma2 and eNOS genes, respectively, are not associated with systolic or diastolic blood pressure, either in men or in women. Our results in a large cohort fail to confirm reports of recent studies suggesting an association of lower blood pressure in patients with DM2 and carriers of Pro12Ala polymorphism.

Association between the PPARalpha L162V polymorphism, plasma lipoprotein levels, and atherosclerotic disease in patients with diabetes mellitus type 2 and in nondiabetic controls.

BACKGROUND: Peroxisome proliferator activated receptor alpha (PPARalpha) regulates genes involved in lipoprotein metabolism, hemostasis, and inflammation. It thus represents a candidate gene for the risk of dyslipidemia, atherosclerosis, and coronary heart disease (CHD). Nonesterified fatty acids are PPARalpha ligands and their levels are increased in patients with diabetes mellitus type 2 (DM-2). The effects of the polymorphism of PPARalpha on plasma lipids and atherosclerosis development have been until now contradictory. The present study was performed to evaluate the association between the PPARalpha polymorphism L162V and the presence of dyslipidemia and/or atherosclerotic disease in patients with DM-2 in comparison with nondiabetic controls. METHODS AND RESULTS: We determined this polymorphism in 404 subjects with DM-2 and in 438 age and sex-matched nondiabetic controls. The V allele was present in 9.4% of patients with DM-2 and in 11.4% of the control group (P =.34). There was no significant association between the presence of the polymorphism and body mass index. There was no association between the polymorphism and lipoprotein concentrations in either group, independent of lipid-lowering therapy. In patients with DM-2, there was a trend towards a lower prevalence of atherosclerosis in carriers versus noncarriers of the V allele (P =.0837). In the control group, the presence of the V allele was not associated with an altered prevalence of atherosclerotic disease (P =.45). Likewise, there was a trend towards lower CHD prevalence in carriers versus noncarriers of the V allele (P =.0622). The presence of the polymorphism was not associated with CHD in the control group (P =.80). CONCLUSIONS: The data suggest that the PPARalpha polymorphism L162V might protect against the development of atherosclerosis or CHD in patients with DM-2. The absence of an association between the polymorphism and plasma lipoprotein concentrations may suggest that these protective effects are exerted directly on the arterial wall.