Renin system activity as a determinant of response to treatment in hypertension and heart failure

Gender-affirming hormone therapy induces specific DNA methylation changes in blood

Background

DNA methylation is an epigenetic mark that is influenced by underlying genetic profile, environment, and ageing. In addition to X-linked DNA methylation, sex-specific methylation patterns are widespread across autosomal chromosomes and can be present from birth or arise over time. In individuals where gender identity and sex assigned at birth are markedly incongruent, as in the case of transgender people, feminization or masculinization may be sought through gender-affirming hormone therapy (GAHT). GAHT is a cornerstone of transgender care, yet no studies to date have investigated its effect on genome-wide methylation. We profiled genome-wide DNA methylation in blood of transgender women (n = 13) and transgender men (n = 13) before and during GAHT (6 months and 12 months into feminizing or masculinizing hormone therapy).

Results

We identified several thousand differentially methylated CpG sites (DMPs) (Δβ ≥ 0.02, unadjusted p value < 0.05) and several differentially methylated regions (DMRs) in both people undergoing feminizing and masculinizing GAHT, the vast majority of which were progressive changes over time. X chromosome and sex-specific autosomal DNA methylation patterns established in early development are largely refractory to change in association with GAHT, with only 3% affected (Δβ ≥ 0.02, unadjusted p value < 0.05). The small number of sex-specific DMPs that were affected by GAHT were those that become sex-specific during the lifetime, known as sex-and-age DMPs, including DMRs in PRR4 and VMP1 genes. The GAHT-induced changes at these sex-associated probes consistently demonstrated a shift towards the methylation signature of the GAHT-naïve opposite sex, and we observed enrichment of previously reported adolescence-associated methylation changes.

Conclusion

We provide evidence for GAHT inducing a unique blood methylation signature in transgender people. This study advances our understanding of the complex interplay between sex hormones, sex chromosomes, and DNA methylation in the context of immunity. We highlight the need to broaden the field of ‘sex-specific’ immunity beyond cisgender males and cisgender females, as transgender people on GAHT exhibit a unique molecular profile.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-022-01236-4.

Loop Diuretics in the Treatment of Hypertension

Loop diuretics are not recommended in current hypertension guidelines largely due to the lack of outcome data. Nevertheless, they have been shown to lower blood pressure and to offer potential advantages over thiazide-type diuretics. Torsemide offers advantages of longer duration of action and once daily dosing (vs. furosemide and bumetanide) and more reliable bioavailability (vs. furosemide). Studies show that the previously employed high doses of thiazide-type diuretics lower BP more than furosemide. Loop diuretics appear to have a preferable side effect profile (less hyponatremia, hypokalemia, and possibly less glucose intolerance). Studies comparing efficacy and side effect profiles of loop diuretics with the lower, currently widely prescribed, thiazide doses are needed. Research is needed to fill gaps in knowledge and common misconceptions about loop diuretic use in hypertension and to determine their rightful place in the antihypertensive arsenal.

Antihypertensive pharmacogenetics: getting the right drug into the right patient

Pharmacogenetic investigation seeks to identify genetic factors that contribute to interpatient and interdrug variation in responses to antihypertensive drug therapy. Classical studies have characterized single gene polymorphisms of drug metabolizing enzymes that are responsible for large interindividual differences in pharmacokinetic responses to several antihypertensive drugs. Progress is being made using candidate gene and genome scanning approaches to identify and characterize many additional genes influencing pharmacodynamic mechanisms that contribute to interindividual differences in responses to antihypertensive drug therapy. Knowledge of polymorphic variation in these genes will help to predict individual patients' blood pressure responses to antihypertensive drug therapy and may also provide new insights into molecular mechanisms responsible for elevation of blood pressure.

ACE (I/D) genotype as a predictor of the magnitude and duration of the response to an ACE inhibitor drug (enalaprilat) in humans

BACKGROUND

We have investigated the possible effects of contrasting ACE (I/D) genotypes on the responses to the ACE inhibitor enalaprilat in normotensive men.

METHODS AND RESULTS

Subjects with DD (n=12) and II (n=11) ACE genotypes received an intravenous infusion of enalaprilat or placebo. Pressor responses to stepwise, incremental doses of angiotensin I were measured at 1 and 10 hours after dosing. The dose required to raise mean blood pressure by 20 mm Hg (PD20) was calculated individually, and the ratio of PD20 during enalaprilat to that during placebo (dose ratio, DR) was used for assessment of the extent of ACE inhibition. The pressor response was significantly attenuated at 1 hour after enalaprilat in both groups, but significant attenuation was evident at 10 hours after dose only in the II subjects. The DRs at both 1 hour (median, 5.43 versus 2.82, P=0.0035) and 10 hours (2.06 versus 0.84, P=0.0008) after enalaprilat were significantly higher in II subjects than in DD subjects.

CONCLUSIONS

The effect of enalaprilat was significantly greater and lasted longer in normotensive men homozygous for the II ACE genotype. By multivariate analysis, ACE (I/D) genotype and plasma angiotensin II levels were predictive of >50% of the variation in response to ACE inhibition.

Renal hemodynamic response to an angiotensin II antagonist, eprosartan, in healthy men

In view of the vasodilator potential of angiotensin-converting enzyme (ACE) inhibition via prostaglandins and kinins, we asked why renin inhibition induces a larger renal vasodilator response than ACE inhibitors in healthy humans in earlier studies. One possibility was that there was a more complete blockade of the renin system, which could also be achieved by an angiotensin II antagonist, eprosartan. We measured the hormonal and renal hemodynamic responses to eprosartan doses, from 10 to 400 mg in 9 healthy young men in balance on a 10-mmol/d sodium intake. The threshold eprosartan dose to influence renal perfusion was <10 mg, and the 100-mg dose induced a near-maximal vasodilator response of 135+/-19.7 mL x min(-1) x 1.73 m2. When the dose was increased to 400 mg, there was a modest additional increase of 147+/-57 mL x min(-1) x 1.73 m(-2). A highly significant dose-related fall in arterial blood pressure occurred (r=-.97; P<.001), with no indication of a maximal response at 400 mg. In 6 additional subjects, we compared responses to eprosartan on a high salt and a low salt diet. The renal response to 200 mg eprosartan on a high salt diet, 26.0+/-6.6 mL x min(-1) x 1.73 m(-2), was significantly less than that seen with the low salt diet (P<.001). There was no renal partial agonist angiotensin-like effect of eprosartan. Eprosartan reduced sharply the pressor, renal vascular, and hormonal responses to exogenous angiotensin II. The renal vasodilator response to the angiotensin II antagonist eprosartan closely resembles responses to renin inhibition and exceeds previously reported responses to ACE inhibitors. Thus, eprosartan probably exerted its effect via the angiotensin receptor. More complete blockade of the renin system can be achieved by pharmacological interruption at this level, a finding that could have therapeutic implications.

Differential effects of chronic oral antihypertensive therapies on systemic arterial circulation and ventricular energetics in African-American patients

BACKGROUND

A comprehensive evaluation of arterial load characteristics and left ventricular energetics in systemic hypertension has been limited by the need for invasive techniques to access instantaneous aortic pressure and flow. As a consequence of this methodological limitation, no data exist on the effects of long-term antihypertensive therapy on global arterial impedance properties and indexes of myocardial oxygen consumption (MVO2). Using recently validated noninvasive techniques, we compared in hypertensive patients the effects of chronic oral treatment with ramipril, nifedipine, and atenolol on arterial impedance and mechanical power dissipation as well as indexes of MVO2.

METHODS AND RESULTS

Sixteen African-American subjects with systemic hypertension were studied with a randomized, double-blind, crossover protocol. Instantaneous central aortic pressure and flow, from which arterial load characteristics can be derived, were estimated from calibrated subclavian pulse tracings (SPTs) and continuous-wave aortic Doppler velocity in conjunction with two-dimensional (2D) echocardiographic measurements of the aortic annulus, respectively. To derive ventricular wall stress and indexes of MVO2, left ventricular short- (M-mode) and long-axis (2D echo) images were acquired simultaneously with SPTs. Data were collected at the end of a 2-week washout period (predrug control) and after 6 weeks of treatment with each agent. Although all three agents reduced diastolic blood pressure to the same extent, different effects on mean and systolic pressures and vascular impedance properties were noted. Nifedipine reduced total peripheral resistance (TPR; 1744 +/- 398 versus 1290 +/- 215 dyne-s/cm5) and increased arterial compliance (ACL; 1.234 +/- 0.253 versus 1.776 +/- 0.415 mL/mm Hg). This improvement in arterial compliance was not entirely accounted for by the reduction in distending pressure. Ramipril also decreased TPR (1740 +/- 292 versus 1437 +/- 290 dyne-s/cm5) and increased ACL (1.214 +/- 0.190 versus 1.569 +/- 0.424 mL/mm Hg), but with this agent, the change in arterial compliance was explained solely on the basis of a reduction in distending pressure. Atenolol, in contrast, did not affect either TPR or ACL. In agreement with the compliance results, nifedipine and ramipril significantly lowered the first two harmonics of the impedance spectrum, but atenolol did not. None of these agents resulted in a significant change in characteristic impedance or in the relative amplitude of the reflected pressure wave. Total vascular mechanical power and percent of oscillatory power remained unaltered with all antihypertensive treatments. Only ramipril and nifedipine reduced the integral of both meridional and circumferential systolic wall stresses, indicating that MVO2 per beat was reduced with these agents. Stress-time index, a measure of MVO2 per unit time, decreased significantly with ramipril but not with nifedipine because of an increase in heart rate noted in 10 of 16 patients (mean increase, 10 beats per minute). Thus, a reduction in MVO2 coupled with unchanged total vascular mechanical power suggests improved efficiency of ventriculoarterial coupling with ramipril and with nifedipine in the subset of patients in whom heart rate remained unchanged. In contrast, there was no evidence of a reduction in wall stress, stress integral, or stress-time index with atenolol.

CONCLUSIONS

The noninvasive methodology used in this study constitutes a new tool for serial and simultaneous evaluation of arterial hemodynamics and left ventricular energetics in systemic hypertension. In this study, we demonstrate the differential effects of chronic antihypertensive therapies on systemic arterial circulation and indexes of MVO2 in African-American subjects. Consideration of drug-induced differential responses of arterial load and indexes of MVO2 with each drug may provide a more physiological approach to the treatment of systemic hypertension in indivi

Different peripheral vasodilator effects of isradipine in sodium-loaded and sodium-depleted rabbits

1. The influence of acute changes in salt balance on the cardiovascular effects of the calcium antagonist isradipine were investigated in two groups of 6 rabbits pretreated 24 hr before an acute experiment, one by substituting 0.45% NaCl for drinking water, the other one with a subcutaneous injection of 20 mg kg-1 furosemide. 2. On the next day the animals were anaesthetized with barbiturates and 10 ml kg-1 0.9% NaCl or 5% glucose were infused into the salt loaded and salt depleted animals respectively. 3. Regional blood flows were then measured with microspheres before and after i.v. administration of 3 and 10 micrograms kg-1 isradipine (PN200-110). 4. Salt depleted animals had a lower cardiac output and lower flows to several regional vascular beds including the kidneys. 5. The isradipine effects on systemic haemodynamic variables were not different in the two groups. 6. However, the effects on regional blood flows were modified. In salt loaded animals skeletal muscle flow increased more, starting from a higher baseline, yet flow to the kidneys, pancrease and spleen was higher before and decreased significantly more after the calcium antagonist. 7. The results suggest that an alteration in the sodium balance selectively affects the mechanism responsible for vascular tone in a few vascular beds.

Clinical pharmacokinetics of the angiotensin converting enzyme inhibitors. A review

The angiotensin converting enzyme inhibitors are an important therapeutic advance in the treatment of patients with hypertension and congestive heart failure. In addition, they are useful pharmacological probes to assess the contribution of the renin-angiotensin system to circulatory homeostasis. Captopril was the first angiotensin converting enzyme inhibitor approved for use in patients with hypertension and congestive heart failure. It is rapidly absorbed from the gastrointestinal tract, with detectable plasma concentrations apparent as early as 15 minutes. The extent of absorption is between 60 and 75% of an oral dose and peak plasma concentrations occur after approximately one hour. Captopril is primarily excreted by the kidneys via renal tubular secretion. Renal excretion is rapid, with 90% completed in the first 4 hours. The elimination half-life for unchanged captopril is about 1.7 hours and is markedly increased in the presence of renal insufficiency. Once absorbed, captopril is extensively metabolised to several forms, including a disulphide dimer of captopril, a captopril-cysteine disulphide, and other mixed disulphides with endogenous thiol compounds. It is probable that captopril and its pool of metabolites undergo reversible interconversions. Pharmacokinetic properties of captopril in patients with uncomplicated hypertension appear to be the same as in healthy subjects. However, long term administration of captopril leads to increased concentrations of total captopril, probably from the accumulation of captopril metabolites. Despite the number of potential influences on pharmacokinetic properties in patients with congestive heart failure, due to the many abnormalities in gastrointestinal tract oedema and reductions in splanchnic and renal blood flow, the available data suggest that its pharmacokinetic properties in patients with congestive heart failure resemble those in healthy subjects. However, additional data are necessary to confirm this. Enalapril is the second angiotensin converting enzyme inhibitor to become available. Enalapril is a prodrug that is well absorbed from the gastrointestinal tract, with 60 to 70% of an oral dose being absorbed. However, enalapril must be converted by hepatic esterases to the active form, enalaprilat. After the oral administration of enalapril, the tmax for enalapril is one hour, but for enalaprilat it is 4 hours. There is a prolonged terminal elimination phase with enalaprilat being detectable as late as 96 hours after dosing. Thus, enalapril has a much longer duration of action than captopril. Like captopril, enalapril is primarily excreted by the kidneys.(ABSTRACT TRUNCATED AT 400 WORDS)

Black-white contrasts as determinants of cardiovascular risk in childhood: precursors of coronary artery and primary hypertensive diseases

Atherosclerosis and hypertension begin in childhood. Studies of children have identified black-white differences in anthropometric, hormonal, enzymatic, and renal mechanisms related to the development of coronary artery disease and hypertension. Black children have greater body density, higher blood pressure, and higher serum total cholesterol, alpha-lipoprotein cholesterol, and insulin levels, whereas white children have a higher percentage of body fat, a faster heart rate, and higher hemoglobin, serum triglyceride, pre-beta-lipoprotein cholesterol, plasma renin, and dopamine-beta-hydroxylase levels. At puberty, white male children have decreased high-density lipoprotein (HDL) levels and increased low-density lipoprotein/HDL ratios. Black children have lower urinary K+ excretion and demonstrate natriuresis when K+ is administered orally. These black-white contrasts provide clues for studying disease development early in life. Rational approaches to primary prevention of atherosclerosis and hypertension may require a diversity of strategies because of these black-white differences.