High aldosterone-to-renin variants of CYP11B2 and pregnancy outcome

Background. Increased aldosterone concentrations and volume expansion of normal pregnancies are hallmarks of normal pregnancies and blunted in pre-eclampsia. Accordingly, we hypothesized an active mineralocorticoid system to protect from pre-eclampsia. Methods. In pregnant women (normotensive n = 44; pre-eclamptic n = 48), blood pressure, urinary tetrahydro-aldosterone excretion and activating polymorphisms (SF-1 site and intron 2) of the aldosterone synthase gene (CYP11B2) were determined; 185 non-pregnant normotensive individuals served as control. Amino acid-changing polymorphisms of the DNA- and agonist-binding regions of the mineralocorticoid receptor were evaluated by RT-PCR, SSCP and sequencing. Results. Urinary tetrahydro-aldosterone excretion was reduced in pre-eclampsia as compared to normal pregnancy (P < 0.05). It inversely correlated with blood pressure (r = 0.99, P < 0.04). Homozygosity for activating CYP11B2 polymorphisms was preferably present in normotensive as compared to pre-eclamptic pregnancies, identified (intron 2, P = 0.005; SF-1 site, P = 0.016). Two mutant haplotypes decreased the risk of developing pre-eclampsia (RR 0.16; CI 0.05-0.54; P < 0.001). In contrast, intron 2 wild type predisposed to pre-eclampsia (P < 0.0015). No functional mineralocorticoid receptor mutant has been observed. Conclusions. High aldosterone availability is associated with lower maternal blood pressure. In line with this observation, gain-of-function variants of the CYP11B2 reduce the risk of developing pre-eclampsia. Mutants of the mineralocorticoid receptor cannot explain the frequent syndrome of pre-eclampsi

Association between 11β-hydroxysteroid dehydrogenase type 1 gene polymorphisms and metabolic syndrome

ntroduction: The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) catalyzes the con-version of the hormonally inactive cortisone to active cortisol, thus facilitating glucocorticoid receptor activation in target tissues. Increased expression of 11β-HSD1 in adipose tissue has been associated with obesity and insulin resistance. In this study, we investigated the association of two 11β-HSD1 gene (HSD11B1) polymorphisms with the metabolic syndrome (MetS) and its characteristics in the Bosnian population. Materials and methods: The study included 86 participants: 43 patients diagnosed with MetS and 43 healthy controls. Subjects were genotyped for two HSD11B1 gene polymorphisms: rs846910: G>A and rs45487298: insA, by the high resolution melting curve analysis. Genotype distribution and an influence of genotypes on clinical and biochemical parameters were assessed. Results: There was no significant difference in the mutated allele frequencies for the two HSD11B1 gene polymorphisms between MetS patients and controls. In MetS patients, no significant associati-ons between disease-associated traits and rs45487298: insA were found. Regarding rs846910: G>A variant, heterozygous patients (G/A) had significantly lower systolic (P = 0.017) and diastolic blood pressure (P = 0.015), lower HOMA-IR index (P = 0.011) and higher LDL-cholesterol levels (P = 0.049), compared to the wild-type homozygotes. In the control group, rs45487298: insA polymorphism was associated with lower fasting plasma insulin levels (P = 0.041), lower homeostasis model asses-sment insulin resistance (HOMA-IR) index (P = 0.041) and lower diastolic blood pressure (P = 0.048). Significant differences between rs846910: G>A genotypes in controls were not detected. Haplotype analysis confirmed the association of rs45487298: insA with markers of insulin resistance in the con-trol subjects. Conclusions: Our results indicate that a common rs45487298: insA polymorphism in HSD11B1 gene may have a protective effect against insulin resistance

Effects of TCF7L2 rs7903146 variant on metformin response in patients with type 2 diabetes

The response to metformin, the most commonly used drug for the treatment of type 2 diabetes (T2D), is highly variable. The common variant rs7903146 C>T within the transcription factor 7 like 2 gene (TCF7L2) is the strongest genetic risk factor associated with T2D to date. In this study we explored the effects of TCF7L2 rs7903146 genotype on metformin response in T2D. The study included 86 newly diagnosed patients with T2D, incident users of metformin. Levels of fasting glucose, insulin, HbA1c, total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, and anthropometric parameters were measured prior to metformin therapy, and 6 and 12 months after the treatment. Genotyping of TCF7L2 rs7903146 was performed by the Sequenom MassARRAY® iPLEX® platform. At baseline, the diabetes risk allele (T) showed an association with lower triglyceride levels (p = 0.037). After 12 months of metformin treatment, the T allele was associated with 25.9% lower fasting insulin levels (95% CI 10.9-38.3%, p = 0.002) and 29.1% lower HOMA-IR index (95% CI 10.1-44.1%, p = 0.005), after adjustment for baseline values. Moreover, the T allele was associated with 6.7% lower fasting glucose levels (95% CI 1.1-12.0%, p = 0.021), adjusted for baseline glucose and baseline HOMA-%B levels, after 6 months of metformin treatment. This effect was more pronounced in TT carriers who had 16.8% lower fasting glucose levels (95% CI 7.0-25.6%, p = 0.002) compared to the patients with CC genotype. Our results suggest that TCF7L2 rs7903146 variant affects markers of insulin resistance and glycemic response to metformin in newly diagnosed patients with T2D within the first year of metformin treatment

11beta-Hydroxysteroid dehydrogenase type 2 in pregnancy and preeclampsia

Cortisol availability is controlled by 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2), which inactivates cortisol in cortisone, unable to bind to the glucocorticoid receptor. The 11beta-HSD2 enzyme activity limits either intracellular cortisol concentrations or within the uteroplacental compartment the transfer of cortisol into the fetal circulation. Mechanisms, by which 11beta-HSD2 activity is controlled, include transcriptional control, posttranscriptional modifications of 11beta-HSD2 transcript half-life, epigenetic regulation via methylation of genomic DNA and direct inhibition of enzymatic activity. The 11beta-HSD2 expression and activity is reduced in preeclampsia and the enzyme activity correlates with factors associated with increased vasoconstriction, such as an increased angiotensin II receptor subtype 1 expression, and notably fetal growth. Numerous signals such as proinflammatory cytokines known to be present and/or elevated in preeclampsia regulate 11beta-HSD2 activity. Shallow trophoblast invasion with the resulting hypoxemia seems to critically reduce available 11beta-HSD2 activity. A positive feedback exists as activated glucocorticoid receptors do enhance 11beta-HSD2 mRNA transcription and mRNA stability. No data are currently available on pregnancy and either epigenetic or direct effects on the activity of the translated enzyme

Analysis of CYP2C9*2, CYP2C19*2, and CYP2D6*4 polymorphisms in patients with type 2 diabetes mellitus

This is the first study performed in population from Bosnia & Herzegovina (BH), in which we analysed a significance of genetic variations in drug-metabolising enzyme, cytochrome P450 (CYP), in pathogenesis of Type 2 diabetes. We have determined allele frequencies for CYP2C9*2, CYP2C19*2, and CYP2D6*4 in diabetic patients and nondiabetic controls. Genomic DNA was extracted from blood samples collected from 37 diabetic and 44 nondiabetic subjects. A real-time polymerase chain reaction was used for the detection of specific CYP polymorphisms, with the application of the specific TaqMan’ SNP genotyping tests (AppliedBiosystems). Interestingly, results from this study have demonstrated that frequencies of CYP2C19*2 and CYP2D6*4 variants were in line, while frequency of CYP2C9*2 polymorphism seemed to be lower in this sample of BH population as compared to the Caucasians genotype data. Furthermore, no significant difference in allele frequencies for CYP2C9*2, CYP2C19*2, and CYP2D6*4 was demonstrated between diabetic and nondiabetic subjects. Thus, results form this study seem to indicate no relationship between CYP2C9, CYP2C19, and CYP2D6 genotype and diabetes susceptibility in Bosnian population. This in part may reflect a limited study population included in our study and would require larger cohorts to reveal potential relationships between analysed CYP genetic variants and diabetes risk. In addition, it would be pertinent to further explore possible effects of CYP genetic variations on therapeutic and adverse outcomes of oral antidiabetics, which might be the key in optimising therapy for individual patient with Type 2 diabetes

Analysis of CYP2C9*2, CYP2C19*2, and CYP2D6*4 polymorphisms in patients with type 2 diabetes mellitus

This is the first study performed in population from Bosnia & Herzegovina (BH), in which we analysed a significance of genetic variations in drug-metabolising enzyme, cytochrome P450 (CYP), in pathogenesis of Type 2 diabetes. We have determined allele frequencies for CYP2C9*2, CYP2C19*2, and CYP2D6*4 in diabetic patients and nondiabetic controls. Genomic DNA was extracted from blood samples collected from 37 diabetic and 44 nondiabetic subjects. A real-time polymerase chain reaction was used for the detection of specific CYP polymorphisms, with the application of the specific TaqMan’ SNP genotyping tests (AppliedBiosystems). Interestingly, results from this study have demonstrated that frequencies of CYP2C19*2 and CYP2D6*4 variants were in line, while frequency of CYP2C9*2 polymorphism seemed to be lower in this sample of BH population as compared to the Caucasians genotype data. Furthermore, no significant difference in allele frequencies for CYP2C9*2, CYP2C19*2, and CYP2D6*4 was demonstrated between diabetic and nondiabetic subjects. Thus, results form this study seem to indicate no relationship between CYP2C9, CYP2C19, and CYP2D6 genotype and diabetes susceptibility in Bosnian population. This in part may reflect a limited study population included in our study and would require larger cohorts to reveal potential relationships between analysed CYP genetic variants and diabetes risk. In addition, it would be pertinent to further explore possible effects of CYP genetic variations on therapeutic and adverse outcomes of oral antidiabetics, which might be the key in optimising therapy for individual patient with Type 2 diabetes

High aldosterone-to-renin variants of CYP11B2 and pregnancy outcome

BACKGROUND: Increased aldosterone concentrations and volume expansion of normal pregnancies are hallmarks of normal pregnancies and blunted in pre-eclampsia. Accordingly, we hypothesized an active mineralocorticoid system to protect from pre-eclampsia. METHODS: In pregnant women (normotensive n = 44; pre-eclamptic n = 48), blood pressure, urinary tetrahydro-aldosterone excretion and activating polymorphisms (SF-1 site and intron 2) of the aldosterone synthase gene (CYP11B2) were determined; 185 non-pregnant normotensive individuals served as control. Amino acid-changing polymorphisms of the DNA- and agonist-binding regions of the mineralocorticoid receptor were evaluated by RT-PCR, SSCP and sequencing. RESULTS: Urinary tetrahydro-aldosterone excretion was reduced in pre-eclampsia as compared to normal pregnancy (P < 0.05). It inversely correlated with blood pressure (r = 0.99, P < 0.04). Homozygosity for activating CYP11B2 polymorphisms was preferably present in normotensive as compared to pre-eclamptic pregnancies, identified (intron 2, P = 0.005; SF-1 site, P = 0.016). Two mutant haplotypes decreased the risk of developing pre-eclampsia (RR 0.16; CI 0.05-0.54; P < 0.001). In contrast, intron 2 wild type predisposed to pre-eclampsia (P < 0.0015). No functional mineralocorticoid receptor mutant has been observed. CONCLUSIONS: High aldosterone availability is associated with lower maternal blood pressure. In line with this observation, gain-of-function variants of the CYP11B2 reduce the risk of developing pre-eclampsia. Mutants of the mineralocorticoid receptor cannot explain the frequent syndrome of pre-eclampsia