Dietary sodium restriction prevents vascular endothelial growth factor inhibitor-induced hypertension.

BACKGROUND: Vascular endothelial growth factor inhibitors (VEGFIs) are effective anticancer agents which often induce hypertension. VEGFI-induced hypertension is sodium-sensitive in animal studies. Therefore, the efficacy of dietary sodium restriction (DSR) to prevent VEGFI-induced hypertension in cancer patients was studied. METHODS: Cancer patients with VEGFI-induced hypertension (day mean >135/85 mmHg or a rise in systolic and/or diastolic BP ≥ 20 mmHg) were treated with DSR (aiming at <4 g salt/day). The primary endpoint was the difference in daytime mean arterial blood pressure (MAP) increase between the treatment cycle with and without DSR. RESULTS: During the first VEGFI treatment cycle without DSR, mean daytime MAP increased from 95 to 110 mmHg. During the subsequent treatment cycle with DSR, mean daytime MAP increased from 94 to 102 mmHg. Therefore, DSR attenuated the increase in mean daytime MAP by 7 mmHg (95% CI 1.3-12.0, P = 0.009). DSR prevented the rise in the endothelin-1/renin ratio that normally accompanies VEGFI-induced hypertension (P = 0.020) and prevented the onset of proteinuria: 0.15 (0.10-0.25) g/24 h with DSR versus 0.19 (0.11-0.32) g/24 h without DSR; P = 0.005. DISCUSSION: DSR significantly attenuated VEGFI induced BP rise and proteinuria and thus is an effective non-pharmacological intervention.

The sFlt-1 to PlGF ratio in pregnant women with rheumatoid arthritis: impact of disease activity and sulfasalazine use.

OBJECTIVES: An elevated sFlt-1/PlGF ratio has been validated as a significant predictor of preeclampsia, but has not been established in women with RA. We explored whether the sFlt-1/PlGFratio could be altered due to disease activity in RA, and could be applied in this population to predict preeclampsia. Since SSZ has been suggested to improve the angiogenic imbalance in preeclampsia, we also aimed to examine whether SSZ could affect sFlt-1 or PlGF levels. METHODS: Making use of a nationwide, observational, prospective cohort study on pregnant women with RA, sFlt-1 and PlGF were measured in the third trimester. A total of 221 women, aged 21-42 years, were included, with a median gestational age of 30 + 3 weeks. RESULTS: No differences in sFlt-1 or PlGF were observed between women with high, intermediate or low disease activity (P = 0.07 and P = 0.41), whereas sFlt-1 and PlGF did not correlate with DAS28-CRP score (r = -0.01 and r = -0.05, respectively). Four (2%) women with a sFlt-1/PlGF ratio ≤38 developed preeclampsia in comparison to three (43%) women with a ratio > 38, corresponding to a negative predictive value of 98.1%. SSZ users (n = 57) did not show altered levels of sFlt-1 or PlGF in comparison to non-SSZ users (n = 164, P = 0.91 and P = 0.11). CONCLUSION: Our study shows that in pregnant women with RA, the sFlt-1/PlGF ratio is not altered due to disease activity and a cut-off ≤38 can be used to exclude preeclampsia. Additionally, SSZ use did not affect sFlt-1 or PlGF levels in this population.

Reproducibility and agreement of different non-invasive methods of endothelial function assessment.

Flow-mediated dilatation (FMD) is an established, but investigator-demanding method, used to non-invasively determine nitric oxide (NO)-dependent endothelial function in humans. Local thermal hyperemia (LTH) or post-occlusive reactive hyperemia (PORH) of the skin measured with a laser Doppler flow imager may be a less demanding alternative of FMD. We investigated the reproducibility of the different measures of vascular function, their interrelationship and the NO-dependency of LTH. Measurements were performed twice in 27 healthy men (8 smokers), one week apart. Local application of NG-monomethyl-l-arginine (L-NMMA) by means of iontophoresis was used to determine the NO-dependency of LTH. Using L-NMMA, the peak and plateau responses of LTH were reduced by 31% (p < .001) and 65% (<0.001), respectively. For all measurements the coefficient of variation (CV) was higher in smokers than in non-smokers. For non-smokers the CV of FMD was 12%, of LTH peak response 17%, of LTH plateau response 12%, of PORH peak response 14% and of PORH area under the curve response 11%. FMD correlated weakly with the PORH peak and area under the curve response (r = 0.39 and 0.43, p < .05), whereas the LTH-plateau response correlated with the PORH peak response (r = 0.68, p < .01) in non-smokers, but FMD and LTH peak or plateau responses were unrelated. In conclusion, the LTH plateau response is for two-third NO-dependent, but unrelated to FMD. Furthermore, despite easy to perform the LTH responses are not more reproducible than FMD. Given the weak associations, the different methods of vascular function assessment are not interchangeable.

Altered purinergic signaling in uridine adenosine tetraphosphate-induced coronary relaxation in swine with metabolic derangement.

We previously demonstrated that uridine adenosine tetraphosphate (Up4A) induces potent and partially endothelium-dependent relaxation in the healthy porcine coronary microvasculature. We subsequently showed that Up4A-induced porcine coronary relaxation was impaired via downregulation of P1 receptors after myocardial infarction. In view of the deleterious effect of metabolic derangement on vascular function, we hypothesized that the coronary vasodilator response to Up4A is impaired in metabolic derangement, and that the involvement of purinergic receptor subtypes and endothelium-derived vasoactive factors (EDVFs) is altered. Coronary small arteries, dissected from the apex of healthy swine and swine 6 months after induction of diabetes with streptozotocin and fed a high-fat diet, were mounted on wire myographs. Up4A (10-9-10-5 M)-induced coronary relaxation was maintained in swine with metabolic derangement compared to normal swine, despite impaired endothelium-dependent relaxation to bradykinin and despite blunted P2X7 receptor and NO-mediated vasodilator influences of Up4A. Moreover, a thromboxane-mediated vasoconstrictor influence was unmasked. In contrast, an increased Up4A-mediated vasodilator influence via P2Y1 receptors was observed, while, in response to Up4A, cytochrome P450 2C9 switched from producing vasoconstrictor to vasodilator metabolites in swine with metabolic derangement. Coronary vascular expression of A2A and P2X7 receptors as well as eNOS, as assessed with real-time PCR, was reduced in swine with metabolic derangement. In conclusion, although the overall coronary vasodilator response to Up4A was maintained in swine with metabolic derangement, the involvement of purinergic receptor subtypes and EDVF was markedly altered, revealing compensatory mechanisms among signaling pathways in Up4A-mediated coronary vasomotor influence in the early phase of metabolic derangement. Future studies are warranted to investigate the effects of severe metabolic derangement on coronary responses to Up4A.

Optimum AT1 receptor-neprilysin inhibition has superior cardioprotective effects compared with AT1 receptor blockade alone in hypertensive rats.

Neprilysin inhibitors prevent the breakdown of bradykinin and natriuretic peptides, promoting vasodilation and natriuresis. However, they also increase angiotensin II and endothelin-1. Here we studied the effects of a low and a high dose of the neprilysin inhibitor thiorphan on top of AT1 receptor blockade with irbesartan versus vehicle in TGR(mREN2)27 rats with high renin hypertension. Mean arterial blood pressure was unaffected by vehicle or thiorphan alone. Irbesartan lowered blood pressure, but after 7 days pressure started to increase again. Low- but not high-dose thiorphan prevented this rise. Only during exposure to low-dose thiorphan plus irbesartan did heart weight/body weight ratio, cardiac atrial natriuretic peptide expression, and myocyte size decrease significantly. Circulating endothelin-1 was not affected by low-dose thiorphan with or without irbesartan, but increased after treatment with high-dose thiorphan plus irbesartan. This endothelin-1 rise was accompanied by an increase in renal sodium-hydrogen exchanger 3 protein abundance, and an upregulation of constrictor vascular endothelin type B receptors. Consequently, the endothelin type B receptor antagonist BQ788 no longer enhanced endothelin-1-induced vasoconstriction (indicative of endothelin type B receptor-mediated vasodilation), but prevented it. Thus, optimal neprilysin inhibitor dosing reveals additional cardioprotective effects on top of AT1 receptor blockade in renin-dependent hypertension.

Phosphodiesterase-5 activity exerts a coronary vasoconstrictor influence in awake swine that is mediated in part via an increase in endothelin production.

Nitric oxide (NO)-induced coronary vasodilation is mediated through production of cyclic guanosine monophosphate (cGMP) and through inhibition of the endothelin-1 (ET) system. We previously demonstrated that phosphodiesterase-5 (PDE5)-mediated cGMP breakdown and ET each exert a vasoconstrictor influence on coronary resistance vessels. However, little is known about the integrated control of coronary resistance vessel tone by these two vasoconstrictor mechanisms. In the present study, we investigated the contribution of PDE5 and ET to the regulation of coronary resistance vessel tone in swine both in vivo, at rest and during graded treadmill exercise, and in vitro. ETA/ETB receptor blockade with tezosentan (3 mg/kg iv) and PDE5 inhibition with EMD360527 (300 µg·min(-1)·kg(-1) iv) each produced coronary vasodilation at rest and during exercise as well as in preconstricted isolated coronary small arteries. In contrast, tezosentan failed to produce further coronary vasodilation in the presence of EMD360527, both in vivo and in vitro. Importantly, EMD360527 (3 µM) and cGMP analog 8-Br-cGMP (100 µM) had no significant effects on ET-induced contractions of isolated porcine coronary small arteries, suggesting unperturbed ET receptor responsiveness. In contrast, PDE5 inhibition and cGMP blunted the contractions produced by the ET precursor Big ET, but only in vessels with intact endothelium, suggesting that PDE5 inhibition limited ET production in the endothelium of small coronary arteries. In conclusion, PDE5 activity exerts a vasoconstrictor influence on coronary resistance vessels that is mediated, in part, via an increase in endothelial ET production.

Combining renin-angiotensin system blockade and sodium-glucose cotransporter-2 inhibition in experimental diabetes results in synergistic beneficial effects.

BACKGROUND: Sodium-glucose cotransporter-2 (SGLT2) inhibition exerts cardioprotective and renoprotective effects, often on top of renin-angiotensin system (RAS) blockade. We investigated this in diabetic hypertensive (mREN2)27 rats. METHODS: Rats were made diabetic with streptozotocin and treated with vehicle, the angiotensin receptor blocker valsartan, the SGLT2 inhibitor empagliflozin, or their combination. Blood pressure (BP) was measured by telemetry. RESULTS: Diabetes resulted in albuminuria, accompanied by glomerulosclerosis, without a change in glomerular filtration rate. Empagliflozin did not lower BP, while valsartan did, and when combined the BP drop was largest. Only dual blockade reduced cardiac hypertrophy and prevented left ventricular dilatation. Valsartan, but not empagliflozin, increased renin, and the largest renin rise occurred during dual blockade, resulting in plasma angiotensin II [but not angiotensin-(1-7)] upregulation. In contrast, in the kidney, valsartan lowered angiotensin II and angiotensin-(1-7), and empagliflozin did not alter this. Although both valsartan and empagliflozin alone tended to diminish albuminuria, the reduction was significant only when both drugs were combined. This was accompanied by reduced glomerulosclerosis, no change in glomerular filtration rate, and a favorable expression pattern of fibrosis and inflammatory markers (including SGLT2) in the kidney. CONCLUSION: RAS blockade and SGLT2 inhibition display synergistic beneficial effects on BP, kidney injury and cardiac hypertrophy in a rat with hypertension and diabetes. The synergy does not involve upregulation of angiotensin-(1-7), but may relate to direct RAS-independent effects of empagliflozin in the heart and kidney.

The interplay between tamoxifen and endoxifen plasma concentrations and coagulation parameters in patients with primary breast cancer.

BACKGROUND: Tamoxifen is an effective treatment for primary breast cancer but increases the risk for venous thromboembolism. Tamoxifen decreases anticoagulant proteins, including antithrombin (AT), protein C (PC) and tissue factor (TF) pathway inhibitor, and enhances thrombin generation (TG). However, the relation between plasma concentrations of both tamoxifen and its active metabolite endoxifen and coagulation remains unknown. METHODS: Tamoxifen and endoxifen were measured in 141 patients from the prospective open-label intervention TOTAM-study after 3 months (m) and 6 m of tamoxifen treatment. Levels of AT and PC, the procoagulant TF, and TG parameters were determined at both timepoints if samples were available (n = 53-135 per analysis). Levels of coagulation proteins and TG parameters were correlated and compared between: 1) quartiles of tamoxifen and endoxifen levels, and 2) 3 m and 6 m of treatment. RESULTS: At 3 m, levels of AT, PC, TF and TG parameters were not associated with tamoxifen nor endoxifen levels. At 6 m, median TF levels were lower in patients in the 3rd (56.6 [33] pg/mL), and 4th (50.1 [19] pg/mL) endoxifen quartiles compared to the 1st (lowest) quartile (76 [69] pg/mL) (P=0.027 and P=0.018, respectively), but no differences in anticoagulant proteins or TG parameters were observed. An increase in circulating TF levels (3 m: 46.0 [15] versus 6 m: 54.4 [39] pg/mL, P < 0.001) and TG parameters was observed at the 6 m treatment timepoint, while AT and PC levels remained stable. CONCLUSIONS: Our results indicate that higher tamoxifen and endoxifen levels are not correlated with an increased procoagulant state, suggesting tamoxifen dose escalation does not further promote hypercoagulability.

Uridine adenosine tetraphosphate is a novel vasodilator in the coronary microcirculation which acts through purinergic P1 but not P2 receptors.

Uridine adenosine tetraphosphate (Up4A) has been identified as an endothelium-derived contracting factor, which acts through purinergic P2X and P2Y receptors. Since the coronary vascular actions of Up4A are unknown, we investigated the vasoactive profile of Up4A in coronary microvessels, and studied the involvement of purinergic receptor subtypes. Studies were performed in isolated porcine coronary small arteries (diameter∼250 µm), with and without endothelial denudation, mounted on a Mulvany wire myograph. Purinergic receptor expression was assessed by real-time PCR. Up4A (10(-9)-10(-5) M) failed to induce contraction at basal tone, but produced concentration-dependent vasorelaxation in precontracted microvessels. Up4A was slightly less potent than adenosine, ATP, and ADP in producing vasorelaxation, but significantly more potent than UTP and UDP. mRNA expression of P2X(4), P2Y(1), P2Y(2), P2Y(4), P2Y(6) and A(2A), but not P2X(1), receptors was observed. Up4A-induced vasodilation was unaffected by non-selective P2 receptor antagonist PPADS, P2X(1) antagonist MRS2159, P2Y(1) antagonist MRS2179 and P2Y(6) antagonist MRS2578, but was markedly attenuated by non-selective P1 receptor antagonist 8PT and A(2A) antagonist SCH58261. Up4A-induced vasodilation was not affected by ectonucleotidase inhibitor ARL67156, suggesting that A(2A) stimulation was not the result of Up4A breakdown to adenosine. Up4A-induced vasodilation was blunted in denuded vessels; additional A(2A) receptor blockade further attenuated Up4A-induced vasodilation, suggesting that A(2A) receptor-mediated vasodilation is only partly endothelium-dependent. In conclusion, Up4A exerts a vasodilator rather than a vasoconstrictor influence in coronary microvessels, which is mediated via A(2A) receptors and is partly endothelium-dependent.

Blunted coronary vasodilator response to uridine adenosine tetraphosphate in post-infarct remodeled myocardium is due to reduced P1 receptor activation.

We previously demonstrated that uridine adenosine tetraphosphate (Up4A) exerts a potent vasodilator effect in the healthy porcine coronary vasculature. Since the coronary microvascular effects of Up4A after myocardial infarction (MI) are unknown, the present study investigated the response to Up4A in coronary microvessels from post-MI remodeled porcine myocardium, and the involvement of purinergic receptor subtypes. Coronary small arteries (diameter ∼150 µm) were dissected from the apex of Sham-operated swine and swine in which MI had been produced 5 weeks earlier by transient (2h) occlusion of the left circumflex coronary artery, and mounted on Mulvany wire myographs. Up4A (10(-9)-10(-5)M) produced coronary vasodilation that was reduced in MI as compared to Sham-operated swine. Up4A-induced vasodilation was reduced by P1 blockade with 8-phenyltheophylline in Sham-operated swine and to a lesser extent in MI, while the attenuation by the A2A receptor blocker SCH58261 was similar in Sham-operated and MI swine. Up4A-induced vasodilation remained unaffected by non-selective P2 receptor antagonist PPADS, but was attenuated by selective P2X1 and P2Y1 receptor antagonists MRS2159 and MRS2179, albeit to a similar extent in Sham-operated and MI swine. These responses were paralleled by similar mRNA expression levels of A2A, P2X1 and P2Y1 receptors in MI compared to slaughterhouse control swine. Finally, attenuation of Up4A-induced coronary vasodilation by nitric oxide synthase inhibition was not attenuated in MI as compared to Sham-operated swine. In conclusion, blunted coronary vasodilation in response to Up4A in MI swine is most likely due to reduced activation of P1, rather than P2, receptors and does not involve a loss of NO bioavailability.

Renin and prorenin as biomarkers in hypertension.

PURPOSE OF REVIEW: This review examines the evidence that plasma renin and/or prorenin level may be used to guide therapy in hypertension and as an independent risk factor for future cardiovascular events. RECENT FINDINGS: A large number of retrospective analyses of patient populations in clinical trials, in whom 'baseline' renin measurements were available, supports that high renin, but not high prorenin levels, are indicative of future cardiovascular disease and death, particularly in patients with kidney dysfunction and/or hypertension. The relationship is not affected by the use of renin-angiotensin system (RAS) blockers. High renin levels also tend to support the use of RAS inhibitors as first-choice antihypertensive agents. However, the added value of a renin measurement on top of traditional risk factors is modest, and the pressure response to RAS blockade, even in high-renin patients, varies widely. SUMMARY: Measuring 'baseline' renin as a marker of future cardiovascular events or to determine the choice of drug is of limited value in an individual patient.

The importance of the nitric oxide-cGMP pathway in age-related cardiovascular disease: Focus on phosphodiesterase-1 and soluble guanylate cyclase.

Among ageing-related illnesses, cardiovascular disease (CVD) remains the leading cause of morbidity and mortality causing one-third of all deaths worldwide. Ageing evokes a number of functional, pharmacological and morphological changes in the vasculature, accompanied by a progressive failure of protective and homeostatic mechanisms, resulting in target organ damage. Impaired vasomotor, proliferation, migration, antithrombotic and anti-inflammatory function in both the endothelial and vascular smooth muscle cells are parts of the vascular ageing phenotype. The endothelium regulates these functions by the release of a wide variety of active molecules including endothelium-derived relaxing factors such as nitric oxide, prostacyclin (PGI2 ) and endothelium-derived hyperpolarization (EDH). During ageing, a functional decay of the nitric oxide pathway takes place. Nitric oxide signals to VSMC and other important cell types for vascular homeostasis through the second messenger cyclic guanosine monophosphate (cGMP). Maintenance of proper cGMP levels is an important goal in sustainment of proper vascular function during ageing. For this purpose, different components can be targeted in this signalling system, and among them, phosphodiesterase-1 (PDE1) and soluble guanylate cyclase (sGC) are crucial. This review focuses on the role of PDE1 and sGC in conditions that are relevant for vascular ageing.

Determinants of Maternal Renin-Angiotensin-Aldosterone-System Activation in Early Pregnancy: Insights From 2 Cohorts.

CONTEXT: The corpus luteum (CL) secretes prorenin, renin's inactive precursor. It may thus contribute to the renin-angiotensin-aldosterone-system (RAAS) activation that is required for maternal adaptation in pregnancy. Whether this activation is disturbed in pregnancies lacking a CL is unknown. OBJECTIVE: The objective of this work is to investigate maternal RAAS determinants in early pregnancy. DESIGN AND SETTING: Two observational prospective cohort studies. TOOK PLACE AT: 2 tertiary referral hospitals. PATIENTS AND INTERVENTION(S): Pregnancies (n = 277) were stratified by CL number and in vitro fertilization (IVF) protocol: 0 CL (programmed cycle frozen embryo transfer [FET], n = 28), 1 CL (natural cycle FET, n = 41 and spontaneous conceptions, n = 139), and more than 1 CL (ovarian stimulation and fresh embryo transfer, n = 69). METHODS: Quantification was performed for maternal prorenin, renin, and aldosterone blood levels at 5, 9, and 11 weeks of gestation. RESULTS: Prorenin and renin were lower in the absence of a CL at all time points when compared to 1 CL, whereas prorenin, renin, and aldosterone were higher in the presence of more than 1 CL vs 1 CL (P < .05). Ovarian stimulation with menopausal gonadotropin resulted in higher prorenin, renin, and aldosterone concentrations during the late first trimester than recombinant follicle-stimulating hormone (P < .05). Prorenin, and to a lesser degree renin, correlated positively with serum progesterone and relaxin, but not serum estradiol. Total follicle diameter, body mass index (BMI), polycystic ovary syndrome (PCOS), and antimüllerian hormone (AMH) were additional determinants of circulating prorenin. Finally, pregnancies conceived in the absence of a CL were more disposed to develop preeclampsia. CONCLUSIONS: CL number, IVF protocol, BMI, PCOS, and AMH affect maternal RAAS activation in early pregnancy, and may thus contribute to pregnancy complications.

Renal and hormonal responses to direct renin inhibition with aliskiren in healthy humans.

BACKGROUND: Pharmacological interruption of the renin-angiotensin system focuses on optimization of blockade. As a measure of intrarenal renin activity, we have examined renal plasma flow (RPF) responses in a standardized protocol. Compared with responses with angiotensin-converting enzyme inhibition (rise in RPF approximately 95 mL x min(-1) x 1.73 m(-2)), greater renal vasodilation with angiotensin receptor blockers (approximately 145 mL x min(-1) x 1.73 m(-2)) suggested more effective blockade. We predicted that blockade with the direct oral renin inhibitor aliskiren would produce renal vascular responses exceeding those induced by angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. METHODS AND RESULTS: Twenty healthy normotensive subjects were studied on a low-sodium (10 mmol/d) diet, receiving separate escalating doses of aliskiren. Six additional subjects received captopril 25 mg as a low-sodium comparison and also received aliskiren on a high-sodium (200 mmol/d) diet. RPF was measured by clearance of para-aminohippurate. Aliskiren induced a remarkable dose-related renal vasodilation in low-sodium balance. The RPF response was maximal at the 600-mg dose (197+/-27 mL x min(-1) x 1.73 m(-2)) and exceeded responses to captopril (92+/-20 mL x min(-1) x 1.73 m(-2); P<0.01). Furthermore, significant residual vasodilation was observed 48 hours after each dose (P<0.01). The RPF response on a high-sodium diet was also higher than expected (47+/-17 mL x min(-1) x 1.73 m(-2)). Plasma renin activity and angiotensin levels were reduced in a dose-related manner. As another functional index of the effect of aliskiren, we found significant natriuresis on both diets. CONCLUSIONS: Renal vasodilation in healthy people with the potent renin inhibitor aliskiren exceeded responses seen previously with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. The effects were longer lasting and were associated with significant natriuresis. These results indicate that aliskiren may provide more complete and thus more effective blockade of the renin-angiotensin system.

Impact of left ventricular assist device (LVAD) support on the cardiac reverse remodeling process.

With improved technology and expanding indications for use, left ventricular assist devices (LVADs) are assuming a greater role in the care of patients with end-stage heart failure. Following LVAD implantation with the intention of bridge to transplant, it became evident that some patients exhibit substantial recovery of ventricular function. This prompted explantation of some devices in lieu of transplantation, the so-called bridge-to-recovery (BTR) therapy. However, clinical outcomes following these experiences are not always successful. Patients treated in this fashion have often progressed rapidly back to heart failure. Special knowledge has emerged from studies of hearts supported by LVADs that provides insights into the basic mechanisms of ventricular remodeling and possible limits of ventricular recovery. In general, it was these studies that spawned the concept of reverse remodeling now recognized as an important goal of many heart failure treatments. Important examples of myocardial and/or ventricular properties that do not regress towards normal during LVAD support include abnormal extracellular matrix metabolism, increased tissue angiotensin levels, myocardial stiffening and partial recovery of gene expression involved with metabolism. Nevertheless, studies of LVAD-heart interactions have led to the understanding that although we once considered the end-stage failing heart of patients near death to be irreversibly diseased, an unprecedented degree of myocardial recovery is possible, when given sufficient mechanical unloading and restoration of more normal neurohormonal milieu. Evidence supporting and unsupporting the notion of reverse remodeling and clinical implications of this process will be reviewed.

The role of DNA methylation and histone modifications in blood pressure: a systematic review.

Epigenetic mechanisms might play a role in the pathophysiology of hypertension, a major risk factor for cardiovascular disease and renal failure. We aimed to systematically review studies investigating the association between epigenetic marks (global, candidate-gene or genome-wide methylation of DNA, and histone modifications) and blood pressure or hypertension. Five bibliographic databases were searched until the 7th of December 2018. Of 2984 identified references, 26 articles based on 25 unique studies met our inclusion criteria, which involved a total of 28,382 participants. The five studies that assessed global DNA methylation generally found lower methylation levels with higher systolic blood pressure, diastolic blood pressure, and/or presence of hypertension. Eighteen candidate-gene studies reported, in total, 16 differentially methylated genes, including renin-angiotensin-system-related genes (ACE promoter and AGTR1) and genes involved in sodium homeostasis and extracellular fluid volume maintenance system (NET promoter, SCNN1A, and ADD1). Between the three identified epigenome-wide association studies (EWAS), lower methylation levels of SULF1, EHMT2, and SKOR2 were found in hypertensive patients as compared with normotensive subjects, and lower methylation levels of PHGDH, SLC7A11, and TSPAN2 were associated with higher systolic and diastolic blood pressure. In summary, the most convincing evidence has been reported from candidate-gene studies, which show reproducible epigenetic changes in the interconnected renin-angiotensin and inflammatory systems. Our study highlights gaps in the literature on the role of histone modifications in blood pressure and the need to conduct high-quality studies, in particular, hypothesis-generating studies that may help to elucidate new molecular mechanisms.

Ultrafine particles and ozone perturb norepinephrine clearance rather than centrally generated sympathetic activity in humans.

Cardiovascular risk rapidly increased following exposure to air pollution. Changes in human autonomic regulation have been implicated based on epidemiological associations between exposure estimates and indirect autonomic nervous system measurements. We conducted a mechanistic study to test the hypothesis that, in healthy older individuals, well-defined experimental exposure to ultrafine carbon particles (UFP) increases sympathetic nervous system activity and more so with added ozone (O3). Eighteen participants (age >50 years, 6 women) were exposed to filtered air (Air), UFP, and UFP + O3 combination for 3 hours during intermittent bicycle ergometer training in a randomized, crossover, double-blind fashion. Two hours following exposure, respiration, electrocardiogram, blood pressure, and muscle sympathetic nerve activity (MSNA) were recorded at supine rest, during deep breathing, and during a Valsalva manoeuvre. Catechols and inflammatory marker levels were measured in venous blood samples. Induced sputum was obtained 3.5 h after exposure. Combined exposure to UFP + O3 but not UFP alone, caused a significant increase in sputum neutrophils and circulating leucocytes. Norepinephrine was modestly increased while the ratio between plasma dihydroxyphenylglycol (DHPG) and norepinephrine levels, a marker for norepinephrine clearance, was reduced with UFP + O3. Resting MSNA was not different (47 ± 12 with Air, 47 ± 14 with UFP, and 45 ± 14 bursts/min with UFP + O3). Indices of parasympathetic heart rate control were unaffected by experimental air pollution. Our study suggests that combined exposure to modest UFP and O3 levels increases peripheral norepinephrine availability through decreased clearance rather than changes in central autonomic activity. Pulmonary inflammatory response may have perturbed pulmonary endothelial norepinephrine clearance.

Different contributions of the angiotensin-converting enzyme C-domain and N-domain in subjects with the angiotensin-converting enzyme II and DD genotype.

BACKGROUND: Angiotensin-converting enzyme (ACE) insertion/deletion (I/D) polymorphism-related differences in ACE concentration do not result in differences in angiotensin levels. METHODS AND RESULTS: To investigate whether this relates to differences in the contribution of the ACE C-domain and N-domain, we quantified, using the C-domain-selective inhibitors quinaprilat and RXPA380, and the N-domain-selective inhibitor RXP407, the contribution of both domains to the metabolism of angiotensin I, bradykinin, the C-domain-selective substrate Mca-BK(1-8), and the N-domain-selective substrate Mca-Ala in serum of IIs, DDs, and 'hyperACE' subjects (i.e., subjects with increased ACE due to enhanced shedding). During incubation with angiotensin I, the highest angiotensin II levels were observed in sera with the highest ACE activity. This confirms that ACE is rate-limiting with regard to angiotensin II generation. C-domain-selective concentrations of quinaprilat fully blocked angiotensin I-II conversion in DDs, whereas additional N-domain blockade was required to fully block conversion in IIs. Both domains contributed to bradykinin hydrolysis in all subjects, and the inhibition profile of RXP407 when using Mca-Ala was identical in IIs and DDs. In contrast, the RXPA380 concentrations required to block C-domain activity when using Mca-BK (1-8) were three-fold higher in IIs than DDs. CONCLUSION: The contributions of the C-domain and N-domain differ between DDs and IIs, and RXPA380 is the first inhibitor capable of distinguishing D-allele ACE from I-allele ACE. The lack of angiotensin II accumulation in DDs in vivo is not because of the often quoted concept that ACE is a nonrate-limiting enzyme. It may relate to the fact that in IIs both the N-domain and C- domain generate angiotensin II, whereas in DDs only the C-domain converts angiotensin I.

The (pro)renin receptor: a new addition to the renin-angiotensin system?

The renin-angiotensin system is still incompletely understood. In particular, the function of prorenin, the inactive precursor of renin, is unknown. Yet, prorenin levels are >10-fold higher than renin levels, and prorenin increases even further in subjects with diabetes mellitus displaying microvascular complications. The recent discovery of a (pro)renin binding receptor may shed light on the role of prorenin. This review discusses the possibility that prorenin binding to this receptor results in prorenin activation, thereby allowing angiotensin generation, and that prorenin simultaneously acts as an agonist of this receptor, inducing angiotensin-independent effects. Transgenic animals overexpressing the receptor, as well as a receptor antagonist are now available, and future studies should reveal to what degree this concept is applicable to humans as well.