Search

Hypertension and obesity in the young population are major risk factors for renal and cardiovascular events, which could arise in adulthood. A candidate-gene approach was applied in a cohort observational study, in which we collected data from 2638 high school adolescent students. Participants underwent anthropometric and blood pressure (BP) measurements, as well as saliva and urine sample collection for genomic DNA extraction and renal function evaluation, respectively. We tested whether candidate genes previously implicated in salt-sensitive hypertension in adults impact BP also among adolescents. Since inflammatory mechanisms may be involved in pathophysiology of hypertension and in endothelial dysfunction and atherosclerosis through reactive oxygen species, the baseline urinary excretion of inflammatory and oxidative stress markers in a subgroup of adolescents stratified according to ADD1 (alpha adducin) rs4961 genotypes was assessed. Regression analysis of BP values with genetic polymorphisms, highlighted an association with a missense variant of LSS (lanosterol synthase, rs2254524), a gene coding for an enzyme involved in endogenous ouabain synthesis. Higher diastolic and systolic BP were associated with LSS A allele ( P =0.011 and P =0.023, respectively). BP resulted associated with 5 more SNPs. The KL (klotho) rs9536314 missense variant was associated with 24 hour urinary Na + excretion ( P =0.0083). Urinary protein tests showed a greater excretion of IL1β (interleukin 1β) and interleukin 10 ( P ADD1 rs4961 T allele. In conclusion, 3 missense gene variants already implicated in adult hypertension impact BP or Na + excretion among adolescents, and, together with activated pro-inflammatory pathways, might predispose to early cardiovascular damage.

Rationale & Objective: Studies of humans and animals have suggested that endogenous ouabain (EO) and related genes are mediators of acute (AKI) and chronic kidney injury. We sought to examine the relationship among EO levels, genetic variants in lanosterol synthase (LSS; an enzyme that catalyzes synthesis of cholesterol, a precursor of EO), and both AKI and chronic kidney injury. Study Design: 2 prospective observational cohort studies and a cross-sectional study of kidney tissue. Setting & Participants: (1) A prospective cohort study of patients undergoing cardiovascular surgery, (2) measurement of EO concentration in kidney tissue removed because of an adjacent tumor, and (3) a prospective cohort study of patients with newly diagnosed essential hypertension. Exposure: Missense variant in LSS (A instead of C allele at rs2254524), which leads to a valine to leucine substitution at amino acid 642. Outcomes: Development of postoperative AKI in the cardiovascular surgery cohort, EO concentration in kidney tissue, and estimated glomerular filtration rate (eGFR) reductions in the essential hypertension cohort. Analytical Approach: Logistic regression for analysis of postoperative AKI, analysis of variance for EO concentration in kidney tissue, and generalized linear models for changes in eGFR over time. Results: AKI incidence following cardiovascular surgery was greater among those with the LSS rs2254524 AA genotype (30.7%) than in those with the CC genotype (17.4%; P = 0.001). LSS rs2254524 AA kidneys had higher EO concentrations than CC kidneys (2.14 ± 0.29 vs 1.25 ± 0.08 ng/g; P < 0.001). In the longitudinal study of patients with essential hypertension (median follow-up, 4 years; range, 1-15 years), eGFR decline was greater among the LSS rs2254524 AA genotype group (−4.39 ± 1.18 mL/min/1.73 m2 per year) than in the AC or CC genotype groups (−1.07 ± 0.55 and −2.00 ± 0.45 mL/min/1.73 m2 per year respectively; P = 0.03). Limitations: These associations do not necessarily represent causal relationships; LSS rs2254524 variants may have effects on other steroid hormones. Conclusions: These findings support the potential value of LSS rs2254524 genotype–based risk stratification to identify patients at high risk for AKI before cardiovascular surgery, as well as predict accelerated eGFR in the setting of hypertension. These findings also suggest that LSS may in part drive EO-mediated kidney damage. EO may represent a new potential therapeutic target for the prevention of AKI and slowing of kidney damage in the setting of hypertension.

Background In mice MEOX2/TCF15 heterodimers are highly expressed in heart endothelial cells and are involved in the transcriptional regulation of lipid transport. In a general population, we investigated whether genetic variation in these genes predicted coronary heart disease (CHD). Results In 2027 participants randomly recruited from a Flemish population (51.0 % women; mean age 43.6 years), we genotyped six SNPs in MEOX2 and four in TCF15. Over 15.2 years (median), CHD, myocardial infarction, coronary revascularisation and ischaemic cardiomyopathy occurred in 106, 53, 78 and 22 participants. For SNPs, we contrasted CHD risk in minor-allele heterozygotes and homozygotes (variant) vs. major-allele homozygotes (reference) and for haplotypes carriers (variant) vs. non-carriers. In multivariable-adjusted analyses with correction for multiple testing, CHD risk was associated with MEOX2 SNPs (P ≤ 0.049), but not with TCF15 SNPs (P ≥ 0.29). The MEOX2 GTCCGC haplotype (frequency 16.5 %) was associated with the sex- and age-standardised CHD incidence (5.26 vs. 3.03 events per 1000 person-years; P = 0.036); the multivariable-adjusted hazard ratio [HR] of CHD was 1.78 (95 % confidence interval, 1.25–2.56; P = 0.0054). For myocardial infarction, coronary revascularisation, and ischaemic cardiomyopathy, the corresponding HRs were 1.96 (1.16–3.31), 1.87 (1.20–2.91) and 3.16 (1.41–7.09), respectively. The MEOX2 GTCCGC haplotype significantly improved the prediction of CHD over and beyond traditional risk factors and was associated with similar population-attributable risk as smoking (18.7 % vs. 16.2 %). Conclusions Genetic variation in MEOX2, but not TCF15, is a strong predictor of CHD. Further experimental studies should elucidate the underlying molecular mechanisms. Electronic supplementary material The online version of this article (doi:10.1186/s12863-015-0272-2) contains supplementary material, which is available to authorized users.

Matrix Gla-protein is a vitamin K–dependent protein that strongly inhibits arterial calcification. Vitamin K deficiency leads to production of inactive nonphosphorylated and uncarboxylated matrix Gla protein (dp–ucMGP). The risk associated with dp–ucMGP in the population is unknown. In a Flemish population study, we measured circulating dp–ucMGP at baseline (1996–2011), genotyped MGP , recorded adverse health outcomes until December 31, 2012, and assessed the multivariable-adjusted associations of adverse health outcomes with dp–ucMGP. We applied a Mendelian randomization analysis using MGP genotypes as instrumental variables. Among 2318 participants, baseline dp–ucMGP averaged 3.61 μg/L. Over 14.1 years (median), 197 deaths occurred, 58 from cancer and 70 from cardiovascular disease; 85 participants experienced a coronary event. The risk of death and non-cancer mortality curvilinearly increased ( P ≤0.008) by 15.0% (95% confidence interval, 6.9–25.3) and by 21.5% (11.1–32.9) for a doubling of the nadir (1.43 and 0.97 μg/L, respectively). With higher dp–ucMGP, cardiovascular mortality log-linearly increased (hazard ratio for dp–ucMGP doubling, 1.14 [1.01–1.28]; P =0.027), but coronary events log-linearly decreased (0.93 [0.88–0.99]; P =0.021). dp–ucMGP levels were associated ( P ≤0.001) with MGP variants rs2098435 , rs4236 , and rs2430692. For non-cancer mortality and coronary events ( P ≤0.022), but not for total and cardiovascular mortality ( P ≥0.13), the Mendelian randomization analysis suggested causality. Higher dp–ucMGP predicts total, non-cancer and cardiovascular mortality, but lower coronary risk. For non-cancer mortality and coronary events, these associations are likely causal.

Hypertension is a prevalent disorder in the world representing one of the major risk factors for heart attack and stroke. These risks are increased in salt sensitive individuals. Hypertension and salt sensitivity are complex phenotypes whose pathophysiology remains poorly understood and, remarkably, salt sensitivity is still laborious to diagnose. Here we present a urinary proteomic study specifically designed to identify urinary proteins relevant for the pathogenesis of hypertension and salt sensitivity. Despite previous studies that underlined the association of UMOD gene variants with hypertension, this work provides novel evidence showing different uromodulin protein level in the urine of hypertensive patients compared to healthy individuals. Notably, we also show that patients with higher level of uromodulin are homozygous for UMOD risk variant and display a decreased level of salt excretion, highlighting the essential role of UMOD in the regulation of salt reabsorption in hypertension. Additionally, we found that urinary nephrin 1, a marker of glomerular slit diaphragm, may predict a salt sensitive phenotype and positively correlate with increased albuminuria associated with this type of hypertension., Highlights • We identified urinary proteins differently excreted in hypertensive patients. • Nephrin 1 might predict salt sensitive phenotype and glomerular complications. • Uromodulin impacts salt homeostasis in hypertension. • We provide new insights into the pathogenesis of hypertension and salt sensitivity.

Twenty years of genetic studies have not contributed to improvement in the clinical management of primary arterial hypertension. Genetic heterogeneity, epistatic-environmental-biological interactions, and the pathophysiological complexity of hypertension have hampered the clinical application of genetic findings. In the companion article, we furnished data from rodents and human cells demonstrating two hypertension-triggering mechanisms-variants of adducin and elevated concentrations of endogenous ouabain (within a particular range)-and their selective inhibition by the drug rostafuroxin. Here, we have investigated the relationship between variants of genes encoding enzymes for ouabain synthesis [LSS (lanosterol synthase) and HSD3B1 (hydroxy-δ-5-steroid dehydrogenase, 3β- and steroid δ-isomerase 1)], ouabain transport {MDR1/ABCB1 [ATP-binding cassette, sub-family B (MDR/TAP), member 1]}, and adducin activity [ADD1 (adducin 1) and ADD3], and the responses to antihypertensive medications. We determined the presence of these variants in newly recruited, never-treated patients. The genetic profile defined by these variants predicted the antihypertensive effect of rostafuroxin (a mean placebo-corrected systolic blood pressure fall of 14 millimeters of mercury) but not that of losartan or hydrochlorothiazide. The magnitude of the rostafuroxin antihypertensive effect was twice that of antihypertensive drugs recently tested in phase 2 clinical trials. One-quarter of patients with primary hypertension display these variants of adducin or concentrations of endogenous ouabain and would be expected to respond to therapy with rostafuroxin. Because the mechanisms that are inhibited by rostafuroxin also underlie hypertension-related organ damage, this drug may also reduce the cardiovascular risk in these patients beyond that expected by the reduction in systolic blood pressure alone. ispartof: Science Translational Medicine vol:2 issue:59 ispartof: location:United States status: published

Objective: Endogenous Ouabain (EO) has been demonstrated to modulate the activity of Na+, K+-ATPase. Our purpose was to measure plasma levels of EO in Meniere's Disease (MD) subjects as a possible predisposing factor to developing and maintaining hydrops. Study Design: Case-control study. Settings: University hospital. Patients: Thirty-nine MD subjects and 29 controls with a lifetime negative history for vertigo and dizziness. Main Outcome Measures: Plasma levels of EO. Results: Plasma EO in MD subjects was in the range between 33 and 504 pmol/L (median, 135.5 pmol/L), whereas in the control group, plasma EO varied between 70 and 724 pmol/L (median, 205 pmol/L). The Mann-Whitney U test detected a statistically significant difference (p = 0.0001). Conclusion: Low plasma levels of EO have been proposed to augment Na-K pump activity, whereas high EO levels show an inhibitory effect on the pump activity. A proper pump activity may be necessary to keep the right ionic amount and osmolarity in endolymph. Although other possibilities may be considered, we suggest that altered control mechanisms of pump activity may be related to the pathogenesis and maintenance of MD.

The importance of excess salt intake in the pathogenesis of hypertension is widely recognized. Blood pressure is controlled primarily by salt and water balance because of the infinite gain property of the kidney to rapidly eliminate excess fluid and salt. Up to fifty percent of patients with essential hypertension are salt-sensitive, as manifested by a rise in blood pressure with salt loading. We conducted a two-stage genetic analysis in hypertensive patients very accurately phenotyped for their salt-sensitivity. All newly discovered never treated before, essential hypertensives underwent an acute salt load to monitor the simultaneous changes in blood pressure and renal sodium excretion. The first stage consisted in an association analysis of genotyping data derived from genome-wide array on 329 subjects. Principal Component Analysis demonstrated that this population was homogenous. Among the strongest results, we detected a cluster of SNPs located in the first introns of PRKG1 gene (rs7897633, p = 2.34E-05) associated with variation in diastolic blood pressure after acute salt load. We further focused on two genetic loci, SLC24A3 and SLC8A1 (plasma membrane sodium/calcium exchange proteins, NCKX3 and NCX1, respectively) with a functional relationship with the previous gene and associated to variations in systolic blood pressure (the imputed rs3790261, p = 4.55E-06; and rs434082, p = 4.7E-03). In stage 2, we characterized 159 more patients for the SNPs in PRKG1, SLC24A3 and SLC8A1. Combined analysis showed an epistatic interaction of SNPs in SLC24A3 and SLC8A1 on the pressure-natriuresis (p interaction = 1.55E-04, p model = 3.35E-05), supporting their pathophysiological link in cellular calcium homeostasis. In conclusions, these findings point to a clear association between body sodium-blood pressure relations and molecules modulating the contractile state of vascular cells through an increase in cytoplasmic calcium concentration.

Defective pressure-natriuresis related to abnormalities in the natriuretic response has been associated with hypertension development. A major signaling pathway mediating pressure natriuresis involves the cGMP-dependent protein kinase 1 (PRKG1) that, once activated by Src kinase, inhibits renal Na + reabsorption via a direct action on basolateral Na-K ATPase and luminal Na–H exchanger type 3, as shown in renal tubuli of animals. Because a clear implication of PRKG1 in humans is still lacking, here we addressed whether PRKG1 polymorphisms affect pressure-natriuresis in patients. Naive hypertensive patients (n=574), genotyped for PRKG1 rs1904694, rs7897633, and rs7905063 single nucleotide polymorphisms (SNPs), underwent an acute Na + loading, and the slope of the pressure–natriuresis relationship between blood pressure and Na + excretion was calculated. The underlying molecular mechanism was investigated by immunoblotting protein quantifications in human kidneys. The results demonstrate that the PRKG1 risk haplotype GAT (rs1904694, rs7897633, rs7905063, respectively) associates with a rightward shift of the pressure–natriuresis curve (0.017±0.004 μEq/mm Hg per minute) compared with the ACC (0.0013±0.003 μEq/mm Hg per minute; P =0.001). In human kidneys, a positive correlation of protein expression levels between PRKG1 and Src ( r =0.83; P r =0.557; P r =0.584; P r =0.691; P + reabsorption, suggestive of a blunt pressure–natriuresis response.