Nicola Glorioso

Effect of the HMG-CoA Reductase Inhibitors on Blood Pressure in Patients With Essential Hypertension and Primary Hypercholesterolemia

Certain hydroxymethylglutaryl coenzyme A reductase inhibitors, ie, statins, may cause vasodilation by restoring the endothelial dysfunction that frequently accompanies hypertension and hypercholesterolemia. Several studies have found that a blood pressure reduction is associated with the use of statins, but conclusive evidence from controlled trials is lacking. After an 8-week placebo and diet run-in period, 30 persons with moderate hypercholesterolemia and untreated hypertension (total cholesterol 6.29+/-0.52 mmol/L, systolic and diastolic blood pressure 149+/-6 and 97+/-2 mm Hg) were randomized in a double-blind manner to placebo or pravastatin (20 to 40 mg/d) in a crossover design. In 25 participants who completed the 32-week trial, pravastatin decreased total and LDL cholesterol (both -1.09 mmol/L, P=0.001), systolic and diastolic blood pressure (-8 and -5 mm Hg, both P=0.001), and pulse pressure (-3 mm Hg, P=0.011) and blunted the blood pressure increase caused by the cold pressor test (-4 mm Hg, P=0.005) compared with placebo. It also reduced the level of circulating endothelin-1 (P=0.001). The blood pressure results were virtually unchanged in stratified analyses according to gender and age and in intention-to-treat analyses that included the 5 patients who dropped out of the study. When the participants were taking either placebo or pravastatin, blood pressure was not significantly correlated with total or LDL cholesterol or with circulating endothelin-1. Pravastatin decreases systolic, diastolic, and pulse pressures in persons with moderate hypercholesterolemia and hypertension. This antihypertensive effect may contribute to the documented health benefits of certain statins.

Cardiovascular Phenotype of a Mouse Strain With Disruption of Bradykinin B2-Receptor Gene

BACKGROUND To evaluate the role of kinins in the regulation of cardiovascular function, we studied the phenotype of a mouse strain with disruption of the bradykinin B2-receptor gene (Bk 2r-/-). METHODS AND RESULTS Under basal conditions, tail-cuff blood pressure was higher in Bk2r-/- than in wild-type Bk2r+/+ and heterozygous Bk2r+/- mice (124+/-1 versus 109+/-1 and 111+/-2 mm Hg, respectively; P<.01 for both comparisons), a difference that was confirmed by measurements of intra-arterial blood pressure in unanesthetized mice. Heart weight was greater in Bk2r-/- than in Bk2r+/+ and Bk2r+/- mice (505+/-10 versus 449+/-12 and 477+/-10 mg/100 g body wt, P<.05). Chronic blockade of B2-receptors by Icatibant (50 nmol/100 g body wt twice a day S.C.) or inhibition of nitric oxide synthase by nitro-L-arginine-methyl ester (0.14 mmol/100 g body wt orally) increased the blood pressure of Bk2r+/+ to the levels of Bk2r-/- mice. Compared with the wild-type strain, both Bk2r-/- and Bk2r+/- mice showed exaggerated vasopressor responses to angiotensin II. In addition, chronic administration of an angiotensin AT1-receptor antagonist reduced the basal blood pressure of Bk2r-/- by 21+/-3 mmHg (P<.05) to the levels of Bk2r+/+. No difference was detected between strains as far as plasma renin activity and the expression of renin and AT1-receptor genes are concerned. Chronic salt loading (0.84 mmol/g chow for 15 days) increased the blood pressure of Bk2r-/- and Bk2r+/- by 34+/-3 and 14+/-6 mm Hg, respectively, whereas it was ineffective in Bk2r+/+. CONCLUSIONS Our results suggest that a normally functioning B2-receptor is essential for the maintenance of cardiovascular homeostasis in mice. Dysfunction of the kallikrein-kinin system could contribute to increase blood pressure levels by leaving the activity of vasoconstrictor agents unbalanced.

Adducin- and Ouabain-Related Gene Variants Predict the Antihypertensive Activity of Rostafuroxin, Part 2: Clinical Studies

Five genetic variants that affect Na,K-ATPase interactions predict the blood pressure response to rostafuroxin but not to losartan and hydrochlorothiazide. Help for Hypertension As if changing its mind about how best to detoxify the body, the kidney first secretes a filtrate that contains almost everything in the blood but then recaptures much of it by pumping essential water, salts, and other molecules back in. The Na+, K+-ATPase, or sodium pump, recaptures sodium salts, and because Na+ is the prime determinant of extracellular fluid volume in the body, regulation of this pump controls blood pressure. Now a pair of papers describes how an antihypertension drug can correct abnormal sodium pumping and how this understanding of the drug’s mechanism points to a genetic signature that can predict whether a patient will respond to the drug. One cause of hypertension is a particular variant(s) of the protein adducin, a modulator of protein exposure on the cell surface that stimulates the sodium pump; a second is high concentrations of endogenous ouabain, an activating ligand for the pump. Both factors abnormally enhance the pump function through the triggering of the Src signaling pathway. Rostafuroxin, a derivative of digitoxigenin, acts as an antihypertensive agent by interfering with both of these ways to activate the sodium pump, preventing an increase in renal tubular Na+ transport and the resulting hypertension. In the first of the companion papers (Ferrandi et al.), the authors explore how rostafuroxin accomplishes its pressure-lowering feat. They show that the drug inhibits the Na+, K+ ATPase-Src-EGFR-ERK signaling activated by mutant adducin or ouabain, normalizing renal cell sodium transport, in two different rodent models of hypertension and in human cells. Upon closer examination of rostafurotoxin’s effects on Src-related phosphorylation in vitro, it became clear that the drug disrupts the ability of the variant adducin and the oubain-bound sodium pump to bind and activate Src at its SH2 domain. In the second of the companion papers (Lanzani et al.), the authors apply these results to patients by examining genetic variants that control the mechanisms of hypertension explored in the first paper. Lanzani et al. inspected genetic alterations in genes that encode enzymes that control ouabain synthesis and transport as well as two variants of adducin. They then tested the ability of these genetic variants to predict the response to rostafuroxin in a group of never-before treated patients with hypertension. Individuals who carried certain combinations of these genetic variants responded well to rostofuroxin, displaying a mean drop in the placebo-corrected blood pressure of about 14 mmHg, a clinically meaningful value. The same genetic signature did not predict the blood pressure response to other antihypertensive drugs with different mechanisms of action. The authors suggest that this genetic signature may exist in about a quarter of hypertensive patients. Finally, rostfuroxin may do more than lower blood pressure. Organ damage is known to be a downstream effect of an overactive Src signaling pathway—one of the byproducts of the hypertension mechanisms studied in this pair of papers. Because rostafuroxin interferes with Src signaling, the drug may curb the secondary damage to the heart, kidney, and brain caused by high blood pressure. Thus the kidney’s seemingly schizophrenic filtering actually represents a multilevel, fine-tuned control of the sodium pump as a means of managing blood pressure. Rostafuroxin can selectively correct hypertension in patients whose pumping mechanism is out of kilter, an advance toward personalized treatment of high blood pressure. 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.

Autosomal recessive hypercholesterolaemia in Sardinia, Italy, and mutations in ARH: A clinical and molecular genetic analysis

BACKGROUND Autosomal recessive hypercholesterolaemia (ARH) is caused by mutations in a putative adaptor protein called ARH. This recessive disorder, characterised by severe hypercholesterolaemia, xanthomatosis, and premature coronary artery disease, is rare except on the island of Sardinia, Italy. Our aim was to ascertain why ARH is more common on Sardinia than elsewhere. METHODS We obtained detailed medical histories, did physical examinations, measured concentrations of lipoproteins, and harvested genomic DNA from 28 Sardinians with ARH from 17 unrelated families. We sequenced the coding regions and consensus splice sites of ARH in probands from these families, and from 40 individuals of non-Sardinian origin who had an autosomal recessive form of hypercholesterolaemia of unknown cause. FINDINGS Two ARH mutations, a frameshift mutation (c432insA) in exon 4 (ARH1) and a nonsense mutation (c65G-->A) in exon 1 (ARH2), were present in all of the 17 unrelated families with ARH. Three of the ARH alleles contained both mutations, as a result of an ancient recombination between ARH1 and ARH2. No regional clustering of the three mutant alleles within Sardinia was apparent. Furthermore, four Italians from the mainland with autosomal recessive hypercholesterolaemia were homozygous for ARH1. INTERPRETATION The small number, high frequency, and dispersed distribution of ARH mutations on Sardinia are consistent with these mutations being ancient and maintained in the Sardinian population because of geographic isolation.

Genomewide association study using a high-density single nucleotide polymorphism array and case-control design identifies a novel essential hypertension susceptibility locus in the promoter region of endothelial NO synthase

Essential hypertension is a multifactorial disorder and is the main risk factor for renal and cardiovascular complications. The research on the genetics of hypertension has been frustrated by the small predictive value of the discovered genetic variants. The HYPERGENES Project investigated associations between genetic variants and essential hypertension pursuing a 2-stage study by recruiting cases and controls from extensively characterized cohorts recruited over many years in different European regions. The discovery phase consisted of 1865 cases and 1750 controls genotyped with 1M Illumina array. Best hits were followed up in a validation panel of 1385 cases and 1246 controls that were genotyped with a custom array of 14 055 markers. We identified a new hypertension susceptibility locus (rs3918226) in the promoter region of the endothelial NO synthase gene (odds ratio: 1.54 [95% CI: 1.37–1.73]; combined P=2.58 · 10−13). A meta-analysis, using other in silico/de novo genotyping data for a total of 21 714 subjects, resulted in an overall odds ratio of 1.34 (95% CI: 1.25–1.44; P=1.032 · 10−14). The quantitative analysis on a population-based sample revealed an effect size of 1.91 (95% CI: 0.16–3.66) for systolic and 1.40 (95% CI: 0.25–2.55) for diastolic blood pressure. We identified in silico a potential binding site for ETS transcription factors directly next to rs3918226, suggesting a potential modulation of endothelial NO synthase expression. Biological evidence links endothelial NO synthase with hypertension, because it is a critical mediator of cardiovascular homeostasis and blood pressure control via vascular tone regulation. This finding supports the hypothesis that there may be a causal genetic variation at this locus.

Genetic polymorphism of the renin-angiotensin-aldosterone system and arterial hypertension in the Italian population: The GENIPER Project

Objective To detect the association of single polymorphisms of the renin–angiotensin–aldosterone system (RAAS), or different combinations thereof, with hypertension. Design and methods The GENIPER database is the result of a collaborative effort of 13 Italian research centres to collect genomic DNA in subjects well characterized in terms of blood pressure status. A total of 2461 subjects (normotensive = 611; hypertensive = 1850) were selected and genotyped for the angiotensin-converting enzyme insertion/deletion (ACE I/D), angiotensinogen (AGT) T/C704, angiotensin receptor type 1 (AT1) A/C1166 and aldosterone synthase (ALDO) T/C−344 genetic variants. Results Allele frequencies were homogeneous over the Italian territory, with the relevant exception of the ACE I/D, the D allele being significantly less frequent in the northern region (61%) than in the rest of the country (67%; P < 0.0001). When comparing allele and genotype distributions in normotensives and hypertensives, the latter presented a small but statistically significant increase of the C allele of AGT T/C704, the A allele of AT1 A/C1166 and the T allele of ALDO T/C−344 polymorphisms (P = 0.018, P = 0.037 and P = 0.015, respectively), with similar trends all over the country. A step-wise logistic regression analysis confirmed these findings, by entering in the model as independent predictors of blood pressure status of AGT T/C704 (P = 0.013), ALDO T/C−344 (P = 0.032) and AT1 A/C1166 polymorphisms (P = 0.075), but not ACE I/D (P = 0.996). We also found some evidence of an additive effect of individual genetic variants of the RAAS, modulating at different levels the same functional pathway, on the risk of developing hypertension, but no synergistic interaction was observed. Conclusions Our results suggest that some allelic variants of RAAS genes carry a small but identifiable risk of developing arterial hypertension.

Early Blockade of Bradykinin B2-Receptors Alters the Adult Cardiovascular Phenotype in Rats

We evaluated whether long-term inhibition of bradykinin B2-receptors by the long-acting antagonist Hoe 140 (D-Arg,[Hyp3,Thi5,D-Tic7,Oic8]-bradykinin) affects the blood pressure of normotensive rats. Neither Hoe 140 (at 75 nmol/d for 8 weeks) nor its vehicle altered systolic pressure of adult rats on a normal or high sodium intake. In further experiments, pairs of Hoe 140-treated rats were mated and their offspring maintained on Hoe 140 and a normal sodium diet. Controls were given vehicle instead of Hoe 140. At 9 weeks of age, rats given Hoe 140 during prenatal and postnatal phases of life showed greater systolic pressures, heart rates, and body weights than controls (122 +/- 1 versus 113 +/- 1 mm Hg, 444 +/- 6 versus 395 +/- 8 beats per minute, 258 +/- 7 versus 213 +/- 3 g, respectively, P < .01), whereas urinary creatinine excretion was reduced (1.13 +/- 0.05 versus 1.36 +/- 0.04 mumol/100 g body wt in controls, P < .05). The difference in blood pressure (confirmed by direct intra-arterial measurement) persisted after 20 days of dietary sodium loading, whereas it was nullified by sodium restriction. In additional experiments, the offspring of untreated rats received Hoe 140 or vehicle from 2 days to 11 weeks of age. At this stage, systolic pressure and body weight were significantly greater in Hoe 140-treated rats compared with controls, and heart rate was similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Hoe 140, a bradykinin B2‐receptor antagonist, on renal function in conscious normotensive rats

1 . The present study was designed to determine if endogenous kinins are involved in the regulation of arterial blood pressure and renal function in conscious rats given deoxycorticosterone enantate (DOC, 25 mg kg−1, s.c., weekly) or vehicle for two weeks. 2 . The bradykinin B2‐receptor antagonist, d‐Arg[Hyp3,Thi5,d‐Tic7,Oic8]‐bradykinin (Hoe 140), at a dose of 300 μg kg−1, s.c., blocked the hypotensive effect of 300 ng kg−1 bradykinin i.a., but it did not alter the blood pressure lowering action of 300 ng kg−1 acetylcholine or prostaglandin E2. Inhibition of the response to bradykinin persisted up to 6 h after the administration of Hoe 140. 3 . Administration of 300 μg kg−1 Hoe 140 s.c. four times a day did not alter mean blood pressure, renal blood flow, or renal function in rats given DOC‐vehicle. However, it decreased urinary volume by 70% (from 48.2 ± 3.8 to 14.3 ± 3.7 ml 24 h−1, P < 0.01) and urinary secretion of sodium by 54% (from 1.02 ± 0.05 to 0.47 ± 0.16 mmol 24 h−1, P < 0.01) and potassium by 30% (from 2.93 ± 0.15 to 2.04 ± 0.15 mmol 24 h−1, P < 0.05) in DOC‐treated rats. Mean blood pressure, glomerular filtration rate and total renal blood flow remained unchanged. 4 . Our results suggest that endogenous kinins play a role in the regulation of renal excretion of water and sodium in the presence of elevated levels of DOC.

Controlled study of the effect of angiotensin converting enzyme inhibition versus calcium-entry blockade on insulin sensitivity in overweight hypertensive patients : Trandolapril Italian Study (TRIS)

OBJECTIVE The aim of this study was to evaluate the effect of trandolapril, an angiotensin converting enzyme inhibitor, on blood pressure, forearm blood flow and insulin sensitivity in comparison with nifedipine gastrointestinal therapeutic system. PATIENTS AND METHODS This is a multicentre, two-way parallel-group, open-label comparative study in 90 overweight hypertensive patients, who were randomly assigned to treatment for 8 weeks with either trandolapril or nifedipine. At baseline and after treatment, all patients underwent an oral glucose tolerance test, an evaluation of their metabolic profiles and a euglycaemic hyperinsulinaemic clamp test. In a subgroup of 18 patients, a forearm study was carried out. RESULTS Blood pressure fell by the second week of treatment and remained significantly reduced compared with baseline in both treatment groups. Plasma triglyceride levels were also significantly reduced after trandolapril therapy, but no significant changes occurred in the other metabolic parameters during treatment with either drug. During the euglycaemic hyperinsulinaemic clamp, whole-body glucose use was similar in the two treatment groups at baseline, and a moderate but statistically significant increase in insulin sensitivity was observed after trandolapril treatment (trandolapril: 5.0 +/- 0.2 versus 4.5 +/- 0.2 mg/kg per min; nifedipine: 4.1 +/- 0.3 versus 4.2 +/- 0.3 mg/kg per min; P < 0.05, versus baseline and trandolapril versus nifedipine treatment). Skeletal muscle glucose uptake was significantly higher after trandolapril than after nifedipine therapy (5.0 +/- 0.7 and 3.0 +/- 0.4 mg/min, respectively; P < 0.01). As forearm blood flow was similar in the two treatment groups at baseline and was unchanged after 8 weeks of therapy, skeletal muscle glucose extraction was significantly greater in the ACE inhibitor treated-group than in the nifedipine comparative group (trandolapril: baseline 21 +/- 2, treatment 24 +/- 3 mg/dl; nifedipine: baseline 18 +/- 3, treatment 16 +/- 2 mg/dl; P < 0.05, trandolapril versus nifedipine treatment). CONCLUSIONS During short-term treatment, ACE inhibition with trandolapril was able to moderately improve insulin sensitivity, in comparison with calcium blockade, and this effect appeared to be independent of the haemodynamic action of the drug.

Chronic inhibition of bradykinin B2-receptors enhances the slow vasopressor response to angiotensin II.

The contribution of endogenous kinins in the regulation of blood pressure of angiotensin-treated rats was evaluated using the new bradykinin B2-receptor antagonist Hoe 140 (D-Arg,[Hyp3,Thi5,D-Tic7, Oic8]-bradykinin). Chronic infusion of Hoe 140 at 75 nmol/d (a dose able to inhibit the vasodepressor effect of an intra-aortic bolus injection of 0.85 nmol/kg bradykinin) did not alter systolic blood pressure (tail-cuff plethysmography). Chronic infusion of angiotensin II (Ang II) induced a dose-related increase in systolic blood pressure and plasma Ang II levels. The vasopressor effect of 40 or 100 nmol/d Ang II was enhanced in rats given chronic infusion of Hoe 140 (by 12 and 14 mm Hg, respectively), whereas the increase in plasma Ang II levels remained unaltered. Furthermore, a low nonpressor dose of Ang II (20 nmol/d) was then able to increase blood pressure during chronic blockade of bradykinin receptors by Hoe 140 (from 126 +/- 3 to 137 +/- 3 mm Hg, P < .05). Combined infusion of 20 nmol Ang II and Hoe 140 did not alter the urinary excretion of sodium and water despite the fact that blood pressure was increased. Potentiation of the pressure effect of Ang II by Hoe 140 was confirmed by direct measurement of mean blood pressure (125 +/- 2 versus 108 +/- 2 mm Hg at 20 nmol, 123 +/- 2 versus 110 +/- 2 mm Hg at 40 nmol, and 139 +/- 2 versus 125 +/- 3 mm Hg at 100 nmol Ang II, P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)