Mineralocorticoid Receptor Antagonism by Eplerenone and Arterial Inflammation in HIV: The MIRABELLA HIV Study

Importance

The risk for atherosclerotic disease is increased 1.5- to 2.0-fold among persons with HIV (PWH). Increased activation of the renin-angiotensin-aldosterone system may contribute to increased arterial inflammation in this population.

Objective

To determine the effects of eplerenone on arterial inflammation among well-treated PWH without known cardiovascular disease (CVD).

Design, Setting, and Participants

Well-treated PWH who participated in the double-blinded, placebo-controlled, Mineralocorticoid Receptor Antagonism for Cardiovascular Health in HIV (MIRACLE HIV) study between February 2017 and March 2022 assessing the effects of eplerenone on myocardial perfusion were invited to participate in the Mineralocorticoid Receptor Antagonism By Eplerenone to Lower Arterial Inflammation in HIV (MIRABELLA) substudy if there was no current statin use. Participants were enrolled in the MIRABELLA study and underwent additional 18F-fludeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET/CT) imaging of the aorta and carotid arteries to assess arterial inflammation over 12 months of treatment with eplerenone vs placebo.

Interventions

Eplerenone, 50 mg, twice a day vs identical placebo.

Main Outcomes and Measures

The primary outcome was change in target to background ratio (TBR), a measure of arterial wall inflammation, in the index vessel after 12 months of treatment. The index vessel was defined as the vessel (aorta, left carotid artery, or right carotid artery) with the highest TBR at baseline in each participant.

Results

A total of 26 participants (mean [SD] age, 54 [7] years; 18 male [69%]) were enrolled in the study. Treatment groups (eplerenone, 13 vs placebo, 13) were of similar age, sex, and body mass index. Eplerenone was associated with a reduction in TBR of the primary end point, the index vessel (eplerenone vs placebo: model treatment effect, -0.31; 95% CI, -0.50 to -0.11; P = .006; percentage change, -12.4% [IQR, -21.9% to -2.6%] vs 5.1% [IQR, -1.6% to 11.0%]; P = .003). We further observed a significant reduction of the TBR of the most diseased segment (MDS) of the index vessel (eplerenone vs placebo: -19.1% [IQR, -27.0% to -11.9%] vs 6.8% [IQR, -9.1% to 12.1%]; P = .007). A similar result was seen assessing the index vessel of the carotids (eplerenone vs placebo: -10.0% [IQR, -21.8% to 3.6%] vs 9.7% [IQR, -9.8% to 15.9%]; P = .046). Reduction in the TBR of MDS of the index vessel on 18F-FDG PET/CT correlated with improvement in the stress myocardial blood flow on cardiac magnetic resonance imaging (Spearman ρ = -0.67; P = .01).

Conclusion and Relevance

In this small randomized clinical trial, eplerenone was associated with reduction in arterial inflammation among well-treated PWH without known CVD. In addition, reductions in arterial inflammation as measured by 18F-FDG PET/CT were related to improvements in stress myocardial perfusion. Further larger studies should explore whether eplerenone is a potential treatment strategy for inflammatory-mediated CVD in PWH.

Trial Registration

ClinicalTrials.gov Identifier: NCT02740179.

Striatin Gene Variants Are Associated With Salt Sensitivity of Blood Pressure by Mechanisms That Differ in Women and Men

BACKGROUND

Salt sensitivity of blood pressure (SSBP) is a substantial risk factor for cardiovascular morbidity and mortality. Striatin (STRN) is critical for estrogen and aldosterone nongenomic signaling. However, the role of biological sex on the SSBP phenotype associated with STRN gene variants remains unexplored.

METHOD

Data from 1306 subjects participating in the Hypertensive Pathotype (HyperPATH) Consortium were used to identify STRN gene single-nucleotide variants associated with SSBP. Haploblock analysis revealed a novel diplotype in the upstream regulatory region of STRN (rs888083 and rs6744560), with 31% of subjects being homozygous for the risk diplotype.

RESULTS

Individuals homozygous for the risk diplotype had significantly greater SSBP than nonrisk diplotypes (P<0.009). While a significant genotype/SSBP association was present in both sexes, their potential mechanisms differed. Women, but not men homozygous risk diplotypes, had significantly greater aldosterone levels than nonrisk diplotypes (5.8±0.4 versus 3.2±0.7 ng/dl; P=0.01; liberal Na+ diet, adjusted). Men, but not women, homozygous risk diplotypes, had significantly reduced renal plasma flow response to Angiotensin II than nonrisk diplotypes (delta 95.2±5.2 versus 122.9±10.2 mL/min per 1.73 m2; P=0.01; liberal Na+ diet, adjusted). The single-nucleotide variants composing the risk diplotype were associated with lower STRN mRNA expression in human tissues (in silico).

CONCLUSION

In women, the primary driver of SSBP is increased aldosterone, while in men, it is reduced renal plasma flow responses. Thus, despite a common hypertensive phenotype (SSBP) in both sexes, the specific treatment approaches might differ to increase therapeutic gain and mitigate adverse effects. These genetic- and sex-based observational results require confirmation in a prospective clinical study.

Protocol for a randomized placebo-controlled clinical trial using pure palmitoleic acid to ameliorate insulin resistance and lipogenesis in overweight and obese subjects with prediabetes

Palmitoleic acid (POA), a nonessential, monounsaturated omega-7 fatty acid (C16:1n7), is a lipid hormone secreted from adipose tissue and has beneficial effects on distant organs, such as the liver and muscle. Interestingly, POA decreases lipogenesis in toxic storage sites such as the liver and muscle, and paradoxically increases lipogenesis in safe storage sites, such as adipose tissue. Furthermore, higher POA levels in humans are correlated with better insulin sensitivity, an improved lipid profile, and a lower incidence of type-2 diabetes and cardiovascular pathologies, such as myocardial infarction. In preclinical animal models, POA improves glucose intolerance, dyslipidemia, and steatosis of the muscle and liver, while improving insulin sensitivity and secretion. This double-blind placebo-controlled clinical trial tests the hypothesis that POA increases insulin sensitivity and decreases hepatic lipogenesis in overweight and obese adult subjects with pre-diabetes. Important to note, that this is the first study ever to use pure (>90%) POA with < 0.3% palmitic acid (PA), which masks the beneficial effects of POA. The possible positive findings may offer a therapeutic and/or preventative pathway against diabetes and related immunometabolic diseases.

Elevated Blood Pressure and Aldosterone Dysregulation in Young Black Women Versus White Women on Controlled Sodium Diets

CONTEXT

Black women have a higher prevalence of hypertension as compared to White women. Differences in dietary sodium intake have been implicated as a contributing factor for the disparities in hypertension.

OBJECTIVE

Our objective was to understand whether young Black women would have higher systolic blood pressure (SBP) than White women even on controlled sodium diets and to determine whether SBP differences were due to differences in dietary sodium intake and/or aldosterone regulation.

DESIGN

The analyses included 525 hypertensive and normotensive women (ages 18-71) from the International Hypertensive Pathotype consortium, who were maintained on liberal sodium (LIB; >200 mEq sodium/day) and restricted sodium (RES; 10 mEq sodium/day) diets.

RESULTS

Multivariate regression analyses (adjusted for age, race, study site, body mass index) found that Black women (ages 18-50) had significantly higher SBP than White women on both sodium diets: +8.7 ± 2.7 mmHg (P-value = .002) on a LIB diet and +8.5 ± 2.5 mmHg (P-value = .001) on a RES diet. Even among 18- to 35-year-olds-who were normotensive and nonobese-Black women had higher SBP: +7.9 ± 2.4 mmHg (P-value = .001) on a LIB diet and +7.6 ± 2.7 mmHg (P-value = .005) on a RES diet. Younger Black women also had higher plasma aldosterone concentration to plasma renin activity ratio (ARR) on both LIB and RES diets as well as a higher sodium-modulated aldosterone suppression-stimulation index-an indicator of aldosterone dysregulation. In younger Black women-but not in White women-there was a significant association between SBP and ARR on both LIB and RES diets.

CONCLUSION

Young Black women had increased SBP and ARR as compared to White women on LIB and RES diets, which offers insights into the possible mechanisms for the increased hypertension and cardiovascular disease risk in an at-risk and understudied population.

Effect of hypoglycemia on baroreflex sensitivity in individuals with type 2 diabetes: implications for autonomic control of cardiovascular function in diabetes

PURPOSE

Hypoglycemia is associated with increased mortality, though the mechanisms underlying this association are not established. Hypoglycemia impairs the counterregulatory hormonal and autonomic responses to subsequent hypoglycemia. It is unknown whether hypoglycemia elicits a generalized impairment in autonomic control of cardiovascular function in individuals with type 2 diabetes. We tested the hypothesis that in individuals with type 2 diabetes, hypoglycemia impairs a key measure of cardiovascular autonomic homeostasis, baroreflex sensitivity.

METHODS

Sixteen individuals with well-controlled type 2 diabetes and without known cardiovascular disease were exposed to two 90-min episodes of experimental hypoglycemia (2.8 mmol/L, 50 mg/dL) on the same day. All individuals experienced a hypoglycemic-hyperinsulinemic clamp in the morning (AM clamp) and again in the afternoon (PM clamp). Baroreflex sensitivity was assessed using the modified Oxford method before the initiation of each hypoglycemic-hyperinsulinemic clamp, during the last 30 min of hypoglycemia, and the following morning. A mixed effects model adjusting for sex, age, BMI, and insulin level, demonstrated a significant effect of hypoglycemia on baroreflex sensitivity. The study is registered at ClinicalTrials.gov (NCT03422471).

RESULTS

Baroreflex sensitivity during PM hypoglycemia was reduced compared to baseline, during AM hypoglycemia, and the next day. Insulin levels positively correlated with baroreflex sensitivity at baseline and during AM hypoglycemia.

CONCLUSION

Exposure to hypoglycemia impairs a key measure of autonomic control of cardiovascular function and, thus, may increase the risk of cardiac arrhythmias and blood pressure lability in individuals with type 2 diabetes. This effect is attenuated in part by increased insulin levels.

CACNA1D Gene Polymorphisms Associate With Increased Blood Pressure and Salt Sensitivity of Blood Pressure in White Individuals

BACKGROUND

Disease-causing mutations in CACNA1D gene occur in aldosterone-producing adenomas and familial hyperaldosteronism. We determined whether single nucleotide polymorphisms in CACNA1D gene associate with higher aldosterone resulting in salt sensitivity of blood pressure (BP) and increased BP in men and women.

METHODS

Data were obtained from the HyperPATH (International Hypertension Pathotypes) cohort, where participants completed a cross-over intervention of liberal and restricted sodium diets. Multi-Ethnic Genotyping Array identified 104 CACNA1D single nucleotide polymorphisms that met quality control. Single nucleotide polymorphism is rs7612148 strongly associated with systolic BP and was selected for study in 521 White participants in 3 scenarios ([1] hypertensives; [2] normotensives; [3] total population=hypertensives+normotensives) using multivariate regression analysis.

RESULTS

In the total population and hypertensives, but not normotensives, risk allele carriers (CC, GC), as compared with nonrisk allele homozygotes (GG), exhibited higher salt sensitivity of BP and, on liberal sodium diet, higher systolic BP, lower baseline and angiotensin II-stimulated aldosterone, and lower plasma renin activity. On restricted sodium diet, BP was similar across genotypes, suggesting sodium restriction corrected/neutralized the genotype effect on BP. Because increased aldosterone did not seem to drive the increased salt sensitivity of BP and increased BP on liberal sodium diet, we assessed renal plasma flow. Renal plasma flow increase from restricted to liberal sodium diets was blunted in risk allele homozygotes in the total population and in hypertensives. A replication study in another cohort HyperPATH B (International Hypertension Pathotypes Cohort B) confirmed BP-genotype associations.

CONCLUSIONS

CACNA1D rs7612148 risk allele associated with increased BP and salt sensitivity of BP, likely due to an impaired ability to increase renal plasma flow in response to a liberal sodium diet and not to excess aldosterone.

Randomized Placebo-Controlled Trial to Evaluate Effects of Eplerenone on Myocardial Perfusion and Function Among Persons With Human Immunodeficiency Virus (HIV)-Results From the MIRACLE HIV Study

BACKGROUND

Increased renin angiotensin aldosterone system (RAAS) activity may contribute to excess cardiovascular disease in people with HIV (PWH). We investigated how RAAS blockade may improve myocardial perfusion, injury, and function among well-treated PWH.

METHODS

Forty PWH, on stable ART, without known heart disease were randomized to eplerenone 50 mg PO BID (n = 20) or identical placebo (n = 20) for 12 months. The primary endpoints were (1) myocardial perfusion assessed by coronary flow reserve (CFR) on cardiac PET or stress myocardial blood flow (sMBF) on cardiac MRI or (2) myocardial inflammation by extracellular mass index (ECMi) on cardiac MRI.

RESULTS

Beneficial effects on myocardial perfusion were seen for sMBF by cardiac MRI (mean [SD]: 0.09 [0.56] vs -0.53 [0.68] mL/min/g; P = .03) but not CFR by cardiac PET (0.01 [0.64] vs -0.07 [0.48]; P = .72, eplerenone vs placebo). Eplerenone improved parameters of myocardial function on cardiac MRI including left ventricular end diastolic volume (-13 [28] vs 10 [26] mL; P = .03) and global circumferential strain (GCS; median [interquartile range 25th-75th]: -1.3% [-2.9%-1.0%] vs 2.3% [-0.4%-4.1%]; P = .03), eplerenone versus placebo respectively. On cardiac MRI, improvement in sMBF related to improvement in global circumferential strain (ρ = -0.65, P = .057) among those treated with eplerenone. Selecting for those with impaired myocardial perfusion (CFR <2.5 and/or sMBF <1.8), there was a treatment effect of eplerenone versus placebo to improve CFR (0.28 [0.27] vs -0.05 [0.36]; P = .04). Eplerenone prevented a small increase in troponin (0.00 [-0.13-0.00] vs 0.00 [0.00-0.74] ng/L; P = .03) without effects on ECMi (0.9 [-2.3-4.3] vs -0.7 [-2.2--0.1] g/m2; P = .38). CD4+ T-cell count (127 [-38-286] vs -6 [-168-53] cells/μL; P = .02) increased in the eplerenone- versus placebo-treated groups.

CONCLUSIONS

RAAS blockade with eplerenone benefitted key indices and prevented worsening of myocardial perfusion, injury, and function among PWH with subclinical cardiac disease when compared with placebo.

CLINICAL TRIALS REGISTRATION

NCT02740179 (https://clinicaltrials.gov/ct2/show/NCT02740179?term=NCT02740179&draw=2&rank=1).

Visceral Adiposity Index as a Measure of Cardiovascular Disease in Persons With Human Immunodeficiency Virus

Background

Persons with well-treated human immunodeficiency virus (HIV) demonstrate a 2-fold higher risk of cardiovascular disease (CVD), which may be related to excess visceral adipose tissue (VAT). The visceral adiposity index (VAI) is a score to approximate VAT by combining biochemical measures with anthropometrics without quantification by imaging. We evaluated VAI in association with cardiometabolic factors among persons with HIV (PWH).

Methods

Forty-five PWH on antiretroviral therapy and virologically controlled with increased abdominal VAT (VAT area >110 cm2 on CT) and no known CVD were included. VAI was calculated using standard sex-specific formulas. Coronary plaque was assessed using coronary CT angiography.

Results

Participants were predominantly male (73%), white (53%), and non-Hispanic (84%), with a mean age of 55 (standard deviation, 7) years. Among PWH, median VAI was calculated to be 4.9 (interquartile range [IQR], 2.8-7.3). Log VAI correlated with log VAT (r = 0.59, P < .0001) and anthropometric measures (body mass index: r = 0.36, P = .02; waist circumference: r = 0.43, P = .004; waist-to-hip ratio: r = 0.33, P = .03). Participants with coronary plaque had a higher VAI compared to those without coronary plaque (median, 5.3 [IQR, 3.4-10.5] vs 2.8 [IQR, 1.8-5.0]; P = .004). VAI (area under the curve = 0.760, P = .008) performed better than the atherosclerotic CVD risk score to predict the presence of plaque in receiver operating characteristic analyses.

Conclusions

VAI may be a useful biomarker of metabolic dysfunction and increased CVD risk that may occur with VAT accumulation in PWH.

Clinical Trials Registration

NCT02740179.

Association Between Life's Simple 7 and Biomarkers of Cardiovascular Disease: Aldosterone, Interleukin-6, C-Reactive Protein

Background To promote ideal cardiovascular health, the American Heart Association recommends adhering to Life's Simple 7 (LS7)-achieving healthy targets for body mass index, physical activity, dietary intake, blood pressure, fasting plasma glucose, and cholesterol, along with smoking abstinence. Poorer achievement of LS7 (lower score) has been associated with the development of hypertension and cardiovascular disease. However, less is known about the associations between LS7 and specific biomarkers linked to cardiovascular health: aldosterone, CRP (C-reactive protein), and IL-6 (interleukin-6). Methods and Results We analyzed 379 individuals (age 18-66 years) from the HyperPATH (International Hypertensive Pathotype), who were maintained on ≥200 mEq of sodium daily for 1 week. We calculated a 14-point summative LS7 score according to participants' baseline data. Based on the range of LS7 score in this population (3-14), we classified participants as "inadequate" (3-6), "average" (7-10), and "optimal" (11-14). Regression analyses found that a higher LS7 score group was associated with lower levels of serum and urinary aldosterone (Ptrend<0.001 and Ptrend=0.001, respectively), lower plasma renin activity (Ptrend<0.001), and a blunted increase in serum aldosterone with angiotensin II infusion (Ptrend=0.023). Being in the "optimal" LS7 score group was associated with lower serum CRP (Ptrend=0.001) and IL-6 (Ptrend=0.001). Conclusions A higher LS7 score was associated with a lower activity of the renin-angiotensin-aldosterone system and lower levels of the inflammatory markers CRP and IL-6. These findings offer a possible link between ideal cardiovascular health targets and biomarkers known to play a central role in the development of cardiovascular disease.

Effects of Mineralocorticoid Receptor Blockade and Statins on Kidney Injury Marker 1 (KIM-1) in Female Rats Receiving L-NAME and Angiotensin II

Kidney injury molecule-1 (KIM-1) is a biomarker of renal injury and a predictor of cardiovascular disease. Aldosterone, via activation of the mineralocorticoid receptor, is linked to cardiac and renal injury. However, the impact of mineralocorticoid receptor activation and blockade on KIM-1 is uncertain. We investigated whether renal KIM-1 is increased in a cardiorenal injury model induced by L-NAME/ANG II, and whether mineralocorticoid receptor blockade prevents the increase in KIM-1. Since statin use is associated with lower aldosterone, we also investigated whether administering eiSther a lipophilic statin (simvastatin) or a hydrophilic statin (pravastatin) prevents the increase in renal KIM-1. Female Wistar rats (8-10 week old), consuming a high salt diet (1.6% Na+), were randomized to the following conditions for 14 days: control; L-NAME (0.2 mg/mL in drinking water)/ANG II (225 ug/kg/day on days 12-14); L-NAME/ANG II + eplerenone (100 mg/kg/day p.o.); L-NAME/ANG II + pravastatin (20 mg/kg/day p.o.); L-NAME/ANG II + simvastatin (20 mg/kg/day p.o.). Groups treated with L-NAME/ANG II had significantly higher blood pressure, plasma and urine aldosterone, cardiac injury/stroke composite score, and renal KIM-1 than the control group. Both eplerenone and simvastatin reduced 24-h urinary KIM-1 (p = 0.0046, p = 0.031, respectively) and renal KIM-1 immunostaining (p = 0.004, p = 0.037, respectively). Eplerenone also reduced renal KIM-1 mRNA expression (p = 0.012) and cardiac injury/stroke composite score (p = 0.04). Pravastatin did not affect these damage markers. The 24-h urinary KIM-1, renal KIM-1 immunostaining, and renal KIM-1 mRNA expression correlated with cardiac injury/stroke composite score (p < 0.0001, Spearman ranked correlation = 0.69, 0.66, 0.59, respectively). In conclusion, L-NAME/ANG II increases renal KIM-1 and both eplerenone and simvastatin blunt this increase in renal KIM-1.

Role of renin-angiotensin-aldosterone system activation and other metabolic variables in relation to arterial inflammation in HIV

BACKGROUND

Arterial inflammation remains increased among persons with HIV (PWH) compared with persons without HIV (PWOH) even when controlling for traditional risk factors. We sought to understand whether increased renin-angiotensin-aldosterone system (RAAS) activation may be related to arterial inflammation in PWH and when compared with PWOH.

DESIGN

Twenty PWH and 9 PWOH followed a controlled, standardized low and liberal sodium diet to simulate a RAAS-activated and RAAS-suppressed state, respectively. We measured serum lipoprotein-associated phospholipase A2 (LpPLA2) concentrations following both conditions to assess the physiologic dynamics of aldosterone in relation to arterial inflammation.

RESULTS

LpPLA2 levels were significantly higher among PWH versus PWOH during both the RAAS-activated state[5.3(4.2, 6.1) versus 4.0(3.0, 4.8)nmol/L, median(interquartile range),p = .01]) and RAAS-suppressed state[4.4(3.9, 5.3) versus 3.8(3.4, 4.1)nmol/L,p = .01]. Among PWH, but not PWOH, LpPLA2 increased significantly with RAAS activation(p = .03). LpPLA2 levels measured during the RAAS-suppressed state among PWH remained relatively higher than LpPLA2 levels under both conditions among PWOH. Log LpPLA2 was related to log aldosterone during the RAAS-activated state(r = .39,p = .04) among all participants. Log LpPLA2 was correlated with visceral fat(r = .46,p = .04) and log systolic blood pressure(r = .57,p = .009) during a RAAS-activated state when an increase in aldosterone was stimulated in HIV.

CONCLUSION

LpPLA2 is increased during a RAAS-activated state among PWH, but not among PWOH. Further, LpPLA2 was increased in both RAAS-activated and suppressed states in PWH compared with PWOH. These data suggest a biological link between increased aldosterone and arterial inflammation in this population. Future studies should test RAAS blockade on arterial inflammation as a targeted treatment approach in HIV.

Evaluation of Mineralocorticoid Receptor Antagonism on Changes in NT-proBNP Among Persons With HIV

Subclinical myocardial dysfunction is prevalent among well-treated persons with HIV (PWH). We have previously demonstrated unique renin-angiotensin-aldosterone system physiology among PWH with metabolic dysregulation. Mineralocorticoid receptor blockade may be a targeted treatment strategy for subclinical heart disease in PWH. Forty-six PWH were randomized to receive either eplerenone 50 mg daily or placebo in a 6-month randomized, double-blinded, placebo-controlled trial. We assessed changes in N-terminal pro-B-type natriuretic peptide (NT-proBNP), a biomarker of cardiac stretch, under controlled posture and dietary conditions. The eplerenone- and placebo-treated groups demonstrated a long duration of HIV with good immunological control. NT-proBNP levels were similar between the groups at baseline (41.1 [20.2, 97.9] vs 48.9 [29.2, 65.4] ng/L, P = .80) and decreased significantly more in the eplerenone- vs placebo-treated groups after 6 months (change NT-proBNP -9.6 [-46.8, 0.3] vs -3.0 [-17.0, 39.9] ng/L, P = .02 for comparison of change between groups). Decreases in NT-proBNP were independent of changes in systolic and diastolic blood pressure, and related to decreases in high-sensitivity C-reactive protein (ρ = 0.32, P = .05) and inversely to increases in serum aldosterone (ρ = -0.33, P = .04) among all participants. Treatment with eplerenone for 6 months vs placebo significantly decreases NT-proBNP levels among PWH, independent of eplerenone’s known blood pressure-lowering effects. Further studies should elucidate whether lowering NT-proBNP in this at-risk metabolic population with subclinical heart disease will offer cardioprotection.

Effect of adrenocorticotropic hormone infusion on circulating sclerostin levels

Glucocorticoid use is the most common cause of secondary osteoporosis. Poor skeletal health related to glucocorticoid use is thought to involve inhibition of the Wnt/β-catenin signaling pathway, a key pathway in osteoblastogenesis. Sclerostin, a peptide produced primarily by osteocytes, is an antagonist of the Wnt/β-catenin signaling pathway, raising the possibility that sclerostin is involved in glucocorticoids' adverse effects on bone. The aim of this study was to determine whether an acute infusion of cosyntropin (i.e. ACTH(1-24)), which increases endogenous cortisol, increases serum sclerostin levels as compared to a placebo infusion. This study was performed using blood samples obtained from a previously published, double-blind, placebo-controlled, randomized, cross-over study among healthy men and women who received infusions of placebo or cosyntropin after being supine and fasted overnight (ClinicalTrials.gov NCT02339506). A total of 17 participants were analyzed. There was a strong correlation (R2 = 0.65, P < 0.0001) between the two baseline sclerostin measurements measured at the start of each visit, and men had a significantly higher average baseline sclerostin compared to women. As anticipated, cosyntropin significantly increased serum cortisol levels, whereas cortisol levels fell during placebo infusion, consistent with the diurnal variation in cortisol. There was no significant effect of cosyntropin as compared to placebo infusions on serum sclerostin over 6-24 h (P = 0.10). In conclusion, this randomized, placebo-controlled study was unable to detect a significant effect of a cosyntropin infusion on serum sclerostin levels in healthy men and women.

Daytime eating prevents internal circadian misalignment and glucose intolerance in night work

Night work increases diabetes risk. Misalignment between the central circadian “clock” and daily behaviors, typical in night workers, impairs glucose tolerance, likely due to internal misalignment between central and peripheral circadian rhythms. Whether appropriate circadian alignment of eating can prevent internal circadian misalignment and glucose intolerance is unknown. In a 14-day circadian paradigm, we assessed glycemic control during simulated night work with either nighttime or daytime eating. Assessment of central (body temperature) and peripheral (glucose and insulin) endogenous circadian rhythms happened during constant routine protocols before and after simulated night work. Nighttime eating led to misalignment between central and peripheral (glucose) endogenous circadian rhythms and impaired glucose tolerance, whereas restricting meals to daytime prevented it. These findings offer a behavioral approach to preventing glucose intolerance in shift workers.

Biological sex modifies aldosterone's secretion at a cellular level

Inconsistencies have been reported on the effect of sex on aldosterone (ALDO) levels leading to clinical confusion. The reasons for these inconsistencies are uncertain but include estrogen and/or its receptor modulating target gene responses to mineralocorticoid receptor activation and ALDO secretagogues' levels. This study's goal was to determine whether ALDO's biosynthesis also differed by sex. Two approaches were used. First, plasma renin activity and aldosterone were measured in rats. Both were significantly higher in males. Secondly, using rat zona glomerulosa (ZG) cells, we assessed three ex vivo areas: (1) activity/levels of early steps in ALDO's biosynthesis (StAR and CYP11A1); (2) activity/levels of a late step (CYP11B2); and (3) the status of the mineralocorticoid receptor (MR)-mediated, ultrashort feedback loop. Females had higher expression of CYP11A1 and StAR and increased CYP11A1 activity (increased pregnenolone/corticosterone levels) but did not differ in CYP11B2 expression or activity (ALDO levels). Activating the ZG's MR (thereby activating the ultrashort feedback loop) reduced CYP11B2's activity similarly in both sexes. Exvivo, these molecular effects were accompanied, in females, by lower ALDO basally but higher ALDO with angiotensin II stimulation. In conclusion, we documented that not only was there a sex-mediated difference in the activity of ALDO's biosynthesis but also these differences at the molecular level help explain the variable reports on ALDO's circulating levels. Basally, both in vivo and ex vivo, males had higher ALDO levels, likely secondary to higher ALDO secretagogue levels. However, in response to acute stimulation, ALDO levels are higher in females because of the greater levels and/or activity of their StAR/CYP11A1.

Coronary Vasculature and Myocardial Structure in HIV: Physiologic Insights From the Renin-Angiotensin-Aldosterone System

The landscape of HIV medicine dramatically changed with the advent of contemporary antiretroviral therapies, which has allowed persons with HIV (PWH) to achieve good virologic control, essentially eliminating HIV-related complications and increasing life expectancy. As PWH are living longer, noncommunicable diseases, such as cardiovascular disease (CVD), have become a leading cause of morbidity and mortality in PWH with rates that are 50% to 100% higher than in well-matched persons without HIV. In this review, we focus on disease of the coronary microvasculature and myocardium in HIV. We highlight a key hormonal system important to cardiovascular endocrinology, the renin-angiotensin-aldosterone system (RAAS), as a potential mediator of inflammatory driven-vascular and myocardial injury and consider RAAS blockade as a physiologically targeted strategy to reduce CVD in HIV.

Genetic Predictors of Salt Sensitivity of Blood Pressure: The Additive Impact of 2 Hits in the Same Biological Pathway

[Figure: see text].

Myeloid Mineralocorticoid Receptor Transcriptionally Regulates P-Selectin Glycoprotein Ligand-1 and Promotes Monocyte Trafficking and Atherosclerosis

Objective

MR (mineralocorticoid receptor) activation associates with increased risk of cardiovascular ischemia while MR inhibition reduces cardiovascular-related mortality and plaque inflammation in mouse atherosclerosis. MR in myeloid cells (My-MR) promotes inflammatory cell infiltration into injured tissues and atherosclerotic plaque inflammation by unclear mechanisms. Here, we examined the role of My-MR in leukocyte trafficking and the impact of sex.

Approach and Results

We confirm in vivo that My-MR deletion (My-MR-KO) in ApoE-KO mice decreased plaque size. Flow cytometry revealed fewer plaque macrophages with My-MR-KO. By intravital microscopy, My-MR-KO significantly attenuated monocyte slow-rolling and adhesion to mesenteric vessels and decreased peritoneal infiltration of myeloid cells in response to inflammatory stimuli in male but not female mice. My-MR-KO mice had significantly less PSGL1 (P-selectin glycoprotein ligand 1) mRNA in peritoneal macrophages and surface PSGL1 protein on circulating monocytes in males. In vitro, MR activation with aldosterone significantly increased PSGL1 mRNA only in monocytes from MR-intact males. Similarly, aldosterone induced, and MR antagonist spironolactone inhibited, PSGL1 expression in human U937 monocytes. Mechanistically, aldosterone stimulated MR binding to a predicted MR response element in intron-1 of the PSGL1 gene by ChIP-qPCR. Reporter assays demonstrated that this PSGL1 MR response element is necessary and sufficient for aldosterone-activated, MR-dependent transcriptional activity.

Conclusions

These data identify PSGL1 as a My-MR target gene that drives leukocyte trafficking to enhance atherosclerotic plaque inflammation. These novel and sexually dimorphic findings provide insight into increased ischemia risk with MR activation, cardiovascular protection in women, and the role of MR in atherosclerosis and tissue inflammation.

Associations of trauma and posttraumatic stress disorder with aldosterone in women

BACKGROUND

Posttraumatic stress disorder (PTSD) has been associated with increased cardiovascular risk, however, underlying mechanisms have not been fully specified. PTSD is associated with stress-related hormones, including dysregulated glucocorticoid activity. Dysregulation of aldosterone, a mineralocorticoid activated by psychological stress and implicated in cardiovascular damage, may be a relevant pathway linking PTSD and cardiovascular risk. Few studies to date have evaluated the association between PTSD and aldosterone, none with repeated measures of aldosterone. We examined if trauma and PTSD were associated with altered aldosterone levels relative to women unexposed to trauma.

METHODS

The association of trauma exposure and chronic PTSD with plasma aldosterone levels was investigated in 521 middle-aged women in the Nurses' Health Study II. Aldosterone was assessed at two time points, 10-16 years apart, and trauma exposure and PTSD were also ascertained for both time points. Regarding exposure assessment, women were characterized based on a structured diagnostic interview as: having chronic PTSD (PTSD at both time points; n = 174); being trauma-exposed (trauma exposure at first time point but no PTSD; n = 174); and being unexposed (no trauma exposure at either time point; reference group for all analyses; n = 173). Linear mixed models examined associations of trauma and PTSD status with log-transformed aldosterone levels, adjusting for covariates and health-related variables that may confound or lie on the pathway between PTSD and altered aldosterone levels.

RESULTS

Across the sample, mean aldosterone concentration decreased over time. Adjusting for covariates, women with chronic PTSD had significantly lower aldosterone levels averaged over time, compared to women unexposed to trauma (β = - 0.08, p = 0.04). Interactions between trauma/PTSD group and time were not significant, indicating change in aldosterone over time did not differ by trauma/PTSD status. Post-hoc exploratory analyses suggested that menopausal status partially mediated the relationship between chronic PTSD status and aldosterone level, such that postmenopausal status explained 7% of the effect of PTSD on aldosterone.

CONCLUSIONS

These findings indicate that PTSD is associated with lower levels of aldosterone. Further work is needed to understand implications of this type of dysregulation in a key biological stress system for cardiovascular and other health outcomes previously linked with PTSD.

Abstract P237: Alterations In Renal Sodium Handling Proteins Determined By Urinary Extracellular Vesicle Analysis During Dietary Sodium Modulation And In Primary Aldosteronism

Sodium handling is altered during extremes in dietary sodium intake or in pathologic conditions such as primary aldosteronism. Urinary extracellular vesicles (uEVs) are excreted by all cell types along the nephron, are enriched for membrane proteins, and could provide insight into renal physiology in humans. We assessed uEV protein excretion of renal epithelial proteins relevant to sodium handling from 54 volunteers with pre-hypertension on high (HS, 200 mmol/d) and low (LS, 10 mmol/d) sodium diet for 5-7 days. To compare pathologic versus physiologic responses to aldosterone excess, samples were collected from 9 patients with primary aldosteronism (PA). uEVs were isolated by ultracentrifugation and trypsin digested proteins were quantified using multiple reaction monitoring mass spectrometry using isotopically labeled standards, normalized to the uEV-specific marker CD9. Wilcoxon signed rank and rank sum tests were used for within-subject and between-subject comparisons, respectively. LS diet altered uEV excretion of pendrin (4.0, expressed as fold-change vs HS), aquaporin-2 (-2.03), TRPV5 (-1.91), NCC (1.51), OSR1 (1.42; P <0.01 for all), and SGLT2 (1.20, P =0.042). In primary aldosteronism, expression of ENaC-α, ENaC-β, and ENaC-γ, NCC, SGLT2, and OSR-1 were increased to a greater extent compared to during LS diet ( P <0.05 for each), whereas AQP2 and TRPV5 were similar to HS diet ( Figure ). Expression of uEV proteins relevant to renal tubular sodium handling are dynamically altered by dietary sodium restriction and aldosterone excess. Further studies could identify patterns specific to pathologic versus physiologic aldosterone responses.

The Role of Thyroid in Renovascular Function: Independent Association of Serum TSH With Renal Plasma Flow

CONTEXT

There are well-established interactions between the thyroid and the kidney. Thyroid hypofunction is associated with reduced renal plasma flow (RPF), and hypothyroidism is highly prevalent in chronic kidney disease; however, less is known about the thyroid-kidney axis in the euthyroid state.

OBJECTIVE

This work aimed to study the association of thyroid function with renovascular parameters in a well-phenotyped cohort of euthyroid normotensive and hypertensive individuals.

METHODS

This cross-sectional, multicenter study of the HyperPATH Consortium took place in 5 US and European academic institutions. A total of 789 individuals, aged 18 to 65 years, with serum thyrotropin (TSH) 0.4 to 5.5 mIU/L, participated; individuals with uncontrolled or secondary hypertension or on medication affecting the hypothalamus-pituitary-thyroid axis were excluded. Hemodynamic parameters including RPF, thyroid function testing, and the Thr92Ala deiodinase 2 (D2) polymorphism were assessed in the setting of a liberal and restricted salt diet. We searched for associations between thyroid function and renovascular parameters and accounted for confounding factors, such as older age, hypertension, and diabetes.

RESULTS

Serum TSH was inversely associated with RPF assessed in the setting both of liberal and restricted salt diets. This association remained significant and independent when accounting for confounding factors, whereas free thyroxine index (fTI) and the Thr92Ala polymorphism, associated with lower D2 catalytic activity and disrupted thyroid hormone tissue availability, were not independently associated with RPF. Serum TSH remained an independent predictor of RPF on a liberal salt diet when the analysis was restricted to healthy young individuals.

CONCLUSION

Serum TSH levels, but not fTI nor the Thr92Ala D2 polymorphism, were independently inversely associated with RPF in individuals of the HyperPATH Consortium. These findings suggest a direct interconnection between TSH and renovascular dynamics even with TSH within reference range, warranting further investigation.

Acute effects of the food preservative propionic acid on glucose metabolism in humans

INTRODUCTION

Propionic acid (PA) is a common food preservative generally recognized as safe by the US Food and Drug Administration; however, exogenous PA has effects on glucose metabolism that are not fully understood. Our preclinical studies demonstrated exogenous PA increases glucagon, norepinephrine, and endogenous glucose production (EGP).

RESEARCH DESIGN AND METHODS

We performed a randomized, placebo-controlled, crossover study in 28 healthy men and women to determine the effect of PA (1500 mg calcium propionate) on these factors. Subjects had two study visits, each preceded by a 1 week, PA-free diet. During each visit, glucose, insulin, glucagon, norepinephrine, epinephrine, and EGP were assessed for 2 hours after oral administration of PA/placebo under resting conditions (protocol 1) and during either a euglycemic (~85-90 mg/dL) or hypoglycemic (~65-70 mg/dL) hyperinsulinemic clamp (protocol 2).

RESULTS

PA, as compared with placebo, significantly increased: (1) glucagon and norepinephrine during protocol 1; (2) glucagon, norepinephrine, and epinephrine under euglycemic conditions in protocol 2; and (3) norepinephrine, epinephrine, and EGP under hypoglycemic conditions in protocol 2.

CONCLUSION

Oral consumption of PA leads to inappropriate activation of the insulin counterregulatory hormonal network. This inappropriate stimulation highlights PA as a potential metabolic disruptor.

Striatin genotype-based, mineralocorticoid receptor antagonist-driven clinical trial: study rationale and design

OBJECTIVES

In human studies and genetically altered mouse studies, variants in the striatin gene (STRN) are associated with increased blood pressure (BP) and aldosterone on a liberal salt diet. This clinical trial is based on the presumed mechanism for striatin-associated HTN - increased aldosterone. It is designed to determine if participants with the STRN risk alleles will have a greater BP reduction on a liberal salt diet with a specific, mechanism-based therapy - a mineralocorticoid receptor antagonist, eplerenone - as compared with a nonspecific anti-hypertensive therapy - amlodipine.

METHODS

One hundred five hypertensive adults with the STRN risk alleles (SNP rs2540923 carriers or rs888083 homozygotes) will be enrolled in a 12-week, double-blind, dose-escalation, clinical trial. After a minimum 2-week washout period and baseline assessment of BP on a liberal salt diet, participants will be randomized to either daily eplerenone or amlodipine. Participants will take daily at-home BP recordings as a safety check. After 4 and 8 weeks of drug therapy, BP will be measured by the study team and medication will be increased, if needed, to achieve a participant goal BP of <140/90 mmHg.Anticipated results We anticipate that STRN risk allele carriers will demonstrate a greater reduction in BP with eplerenone and will require a lower dose of eplerenone to reach goal BP as compared with amlodipine.

CONCLUSION

This is a proof-of-concept clinical trial. Positive results support the feasibility of performing genetically-defined, mechanistically-driven trials in HTN. Clinically, it would suggest that genetic biomarkers can identify individuals highly responsive to specific treatment.

Treatment of Primary Aldosteronism Increases Plasma Epoxyeicosatrienoic Acids

[Figure: see text].

Abstract P235: The Additive Genetic Association of Beta-2 Adrenergic Receptor and Serum-and-Glucocorticoid-Inducible Kinase 1 on Salt-Sensitive Hypertension

Salt sensitivity of blood pressure (SSBP) is associated with increased cardiovascular morbidity. A diplotype on the beta 2 adrenergic receptor (β2AR) gene (rs1042713, rs1042714)—associated with increased aldosterone (ALDO)—and a polymorphism in the serum-and-glucocorticoid-inducible kinase 1 (SGK1) gene (rs2758151)—an ALDO target that increases sodium reabsorption—are each associated with SSBP. We hypothesized that SSBP will be increased in homozygotes for both β2AR and SGK1 (Combo) when compared to non-risk homozygotes and homozygotes in either gene alone.

The HyperPATH database includes individuals who completed 7 days of both restricted and liberal sodium diets to determine systolic SSBP. We conducted a gene association study in 329 individuals: 42 were homozygotes for Combo; 242 were homozygotes for β2AR or SGK1; and 45 were non-carriers.

Multivariate regression analyses (adjusted for age, sex, BMI, race, hypertension) found a significantly higher SSBP in the Combo homozygotes when compared to non-carriers and homozygotes for either β2AR or SGK1(p<0.001, 95% CI: 2.35, 7.56) (Figure 1). Serum ALDO levels were higher in Combo homozygotes than in the other groups (p=0.035, CI: 0.069,1.87). Additionally, analyses of either gene alone with SSBP (β2AR: p=0.056, CI: -0.038, 2.89; SGK1: p=0.003, CI: 0.87, 4.35) was less than what was observed in the Combo. In sum, Combo homozygotes for SGK1 and β2AR substantially increased the level of SSBP compared to that observed in risk allele homozygotes in each gene alone. Thus, hypertensive Combo homozygotes are likely candidates for mineralocorticoid receptor antagonist therapy—gene driven, personalized medicine.

Figure 1.

Abstract P228: Mineralocorticoid Receptor Antagonist And Lipophilic Statin Reduce Urinary Kidney Injury Marker 1 (Kim-1) In Female Rats Receiving L-NAME And Angiotensin II

Statins have beneficial cardiovascular effects some of which appear to be cholesterol-independent and the mechanisms for these latter effects are still unclear. Urinary kidney injury molecule-1 (Kim-1) is a sensitive biomarker of acute renal injury and in clinical studies predicts cardiovascular disease. Aldosterone causes both cardiac and renal injury and a few studies suggest that aldosterone is associated with increased Kim-1. Therefore, in this study we used the N omega-nitro-L-arginine methyl ester (L-NAME)/Angiotensin II (AngII) model of cardiorenal injury to determine whether urinary Kim-1 correlates with the degree of cardiac injury/stroke and whether blockade of the mineralocorticoid receptor prevents increases in urinary Kim-1. Further, since our group reported previously that lipophilic statins, but not hydrophilic statins reduce aldosterone levels, we also asked whether administration of either a lipophilic or a hydrophilic statin affects Kim-1 levels.

To test the hypothesis, 8-10 week-old, female Wistar rats consuming liberal salt diet (1.6% Na + ) were randomized to the following conditions for 14 days: control; L-NAME (0.2 mg/ml in drinking water)/AngII (225ug/kg/day for days 12-14 only); L-NAME/AngII + eplerenone (100 mg/kg/day p.o.); L-NAME/Ang II + pravastatin (hydrophilic statin-20 mg/kg/day p.o.); L-NAME/Ang II + simvastatin (lipophilic statin-20 mg/kg/day p.o.) groups.

Groups treated with L-NAME/AngII had significantly higher blood pressure, urine aldosterone and plasma aldosterone levels compared to control. L-NAME/AngII treatment increased cardiac injury/stroke composite score, including cardiac histopathology evaluation and stroke status, and

24 hour-urinary Kim-1 compared to control. Eplerenone reduced cardiac injury/stroke composite score (p=0.04) and both eplerenone and simvastatin reduced urinary Kim-1 (p=0.0046, p=0.031, respectively). Pravastatin had no effect on these damage markers. Urinary Kim-1 correlated with cardiac injury/stroke composite score (p<0.0001, spearman ranked correlation=0.67).

In conclusion, in a rat model of L-NAME/AngII induced cardiovascular injury, urinary Kim-1 predicts cardiac/stroke injury; eplerenone and simvastatin reduced urinary Kim-1.

Interplay Between Statins, Cav1 (Caveolin-1), and Aldosterone

Statin use is associated with lower aldosterone levels. We hypothesized that caveolin-1 may be important for the uptake of statins into the adrenal gland and would affect statin’s aldosterone-lowering effects. The aim of this study was to test whether the caveolin-1 risk allele (rs926198) would affect aldosterone levels associated with statin use. The Hypertensive Pathotype database includes healthy and hypertensive individuals who have undergone assessment of adrenal hormones. Individuals were studied off antihypertensive medications but were maintained on statins if prescribed by their personal physician. Adrenal hormones were measured at baseline and after 1 hour of angiotensin II stimulation on both high- and low-sodium diets. A mixed-model repeated-measures analysis was employed with a priori selected covariates of age, sex, body mass index, and protocol (low versus high sodium, baseline versus angiotensin II stimulated aldosterone). A total of 250 individuals were included in the study; 31 individuals were taking statins (12.4%) and 219 were not. Among statin users, carrying a caveolin-1 risk allele resulted in a 25% (95% CI, 1–43.2) lower aldosterone level (P=0.04). However, among nonstatin users, carrying a caveolin-1 risk allele resulted in no significant effect on aldosterone levels (P=0.38). Additionally, the interaction between caveolin-1 risk allele and statin use on aldosterone levels was significant (P=0.03). These findings suggest caveolin-1 risk allele carrying individuals are likely to receive the most benefit from statin’s aldosterone-lowering properties; however, due to the observational nature of this study, these findings need further investigation.

A clinical trial to evaluate the effect of statin use on lowering aldosterone levels

BACKGROUND

Statins are the first-line pharmaceutical agent in the management of hypercholesterolemia and cardiovascular (CV) risk reduction, and the most commonly prescribed class of drugs worldwide. Studies describing CV risk reduction independent of LDL-cholesterol lowering have evoked an interest in the pleiotropic mechanisms of statins' benefits. We recently demonstrated that administration of statins in animal models lowers aldosterone levels and observed an association between statin use and reduced aldosterone levels in two human cohorts, with lipophilic statins displaying a greater effect than hydrophilic statins. Therefore, we designed a randomized, placebo-controlled, double-blinded intervention study to assess whether statin treatment lowers aldosterone in a type-dependent manner in humans, with simvastatin (lipophilic) showing a greater effect than pravastatin (hydrophilic).

METHODS/DESIGN

One hundred five healthy participants will be recruited from the general population to enroll in a 12-week, randomized, placebo-controlled, double-blinded, 3-arm clinical trial. Ninety participants are anticipated to complete the protocol. After baseline assessment of aldosterone levels, participants will be randomized to daily simvastatin, pravastatin, or placebo. Aldosterone levels will be assessed after 2 days on study drug and again after 6 weeks and 12 weeks on study drug. Prior to each aldosterone assessment, participants will consume an isocaloric sodium and potassium-controlled run-in diet for 5 days. Assessments will occur on an inpatient research unit to control for diurnal, fasting, and posture conditions. The primary outcome will compare 12-week angiotensin II-stimulated serum aldosterone by study drug. Secondary outcomes will compare baseline and 12-week 24-h urine aldosterone by study drug.

DISCUSSION

Results from this rigorous study design should provide strong support that statins lower aldosterone levels in humans. These results may explain some of the beneficial effects of statins that are not attributed to the LDL-lowering effect of this important class of medications. Results would demonstrate that statin lipophilicity is an important attribute in lowering aldosterone levels. The outcomes of this program will have implications for the design of studies involving statin medications, as well as for the differential use of classes of statins.

TRIAL REGISTRATION

ClinicalTrials.gov; NCT02871687 ; First Posted August 18, 2016.

ACTH Infusion Impairs Baroreflex Sensitivity-Implications for Cardiovascular Hypoglycemia-Associated Autonomic Failure

CONTEXT

Hypoglycemia attenuates cardiovascular homeostatic autonomic control. This attenuation, known as the cardiovascular component of hypoglycemia-associated autonomic failure (HAAF), is characterized most notably by decreased baroreflex sensitivity (BRS) that begins during hypoglycemia and persists until at least the next day, despite return to euglycemia. Understanding the mechanisms underlying this reduction in BRS is important because BRS attenuation is associated with increased morbidity and mortality.

OBJECTIVE

The objective of this work is to investigate the role of the adrenocorticotropin (ACTH)-adrenal axis in decreasing BRS. We tested the hypothesis that infusion of ACTH 1-24 (cosyntropin), as compared to placebo, would acutely suppress BRS, and that this decrease in BRS would be present the next day.

DESIGN

A double-blind, placebo-controlled, random-order, cross-over study was conducted.

SETTING

This study took place in a clinical research center.

PARTICIPANTS

Participants included healthy men and women.

INTERVENTIONS

Interventions included an intravenous infusion of cosyntropin (70 μg/hour for 2.5 hours in the morning and again in the early afternoon) vs normal saline placebo.

MAIN OUTCOME MEASURES

Outcome measures included BRS during and 16 hours after cosyntropin vs placebo infusions.

RESULTS

Cosyntropin infusion attenuated BRS (mm Hg/ms) as compared to placebo (baseline 17.8 ± 1.38 vs 17.0 ± 2.07; during 14.4 ± 1.43 vs 17.3 ± 1.65; and next day 14.8 ± 1.42 vs 18.9 ± 2.04; P < .05, time by treatment, analysis of variance). BRS was decreased during the final 30 minutes of the morning cosyntropin infusion as compared to baseline (P < .01) and remained suppressed the next day (16 hours after afternoon infusion) (P < .025). Placebo infusion did not significantly change BRS. Corrected QT interval was not affected.

CONCLUSIONS

ACTH attenuates BRS, raising the possibility that hypoglycemia-induced increases in ACTH may contribute to the cardiovascular component of HAAF.

Striatin heterozygous mice are more sensitive to aldosterone-induced injury

Aldosterone modulates the activity of both epithelial (specifically renal) and non-epithelial cells. Binding to the mineralocorticoid receptor (MR), activates two pathways: the classical genomic and the rapidly activated non-genomic that is substantially modulated by the level of striatin. We hypothesized that disruption of MR's non-genomic pathway would alter aldosterone-induced cardiovascular/renal damage. To test this hypothesis, wild type (WT) and striatin heterozygous knockout (Strn+/-) littermate male mice were fed a liberal sodium (1.6% Na+) diet and randomized to either protocol one: 3 weeks of treatment with either vehicle or aldosterone plus/minus MR antagonists, eplerenone or esaxerenone or protocol two: 2 weeks of treatment with either vehicle or L-NAME/AngII plus/minus MR antagonists, spironolactone or esaxerenone. Compared to the WT mice, basally, the Strn+/- mice had greater (~26%) estimated renal glomeruli volume and reduced non-genomic second messenger signaling (pAkt/Akt ratio) in kidney tissue. In response to active treatment, the striatin-associated-cardiovascular/renal damage was limited to volume effects induced by aldosterone infusion: significantly increased blood pressure (BP) and albuminuria. In contrast, with aldosterone or L-NAME/AngII treatment, striatin deficiency did not modify aldosterone-mediated damage: in the heart and kidney, macrophage infiltration, and increases in aldosterone-induced biomarkers of injury. All changes were near-normalized following MR blockade with spironolactone or esaxerenone, except increased BP in the L-NAME/AngII model. In conclusion, the loss of striatin amplified aldosterone-induced damage suggesting that aldosterone's non-genomic pathway is protective but only related to effects likely mediated via epithelial, but not non-epithelial cells.

Serum Lipocalin 2 (Neutrophil Gelatinase-Associated Lipocalin) in Relation to Biomarkers of Inflammation and Cardiac Stretch During Activation of the Renin-Angiotensin-Aldosterone System in Human Immunodeficiency Virus

PURPOSE

To evaluate the relationship of lipocalin 2 to inflammation and cardiac injury with increased aldosterone in human immunodeficiency virus (HIV).

METHODS

A standardized 6-day low-sodium diet was used to stimulate renin-angiotensin-aldosterone system (RAAS) activation, and serum lipocalin 2 and biomarkers of inflammation and cardiac stretch were assessed among persons with or without HIV.

RESULTS

Lipocalin 2 levels increased with RAAS activation compared with suppression in the HIV group (median level [interquartile range], 71.3 [59.2-99.7] vs 67.0 [51.8-86.3] ng/mL; P = .01). During RAAS activation, lipocalin 2 was related to biomarkers of inflammation (tumor necrosis factor α [P = .007]), monocyte/macrophage activation (soluble CD163 [P = .005] and chemokine [C-C motif] ligand 2 [P = .03]), and markers of cardiac stretch (brain natriuretic peptide [P < .001] and N-terminal fragment of the prohormone brain natriuretic peptide [P = .001]) in HIV.

CONCLUSION

Lipocalin 2 may be important in modulating aldosterone-induced inflammation, monocyte activation, and cardiac stretch during RAAS activation in HIV.

CLINICAL TRIAL REGISTRATION

NCT01407237.

mTORC1 Deficiency Modifies Volume Homeostatic Responses to Dietary Sodium in a Sex-Specific Manner

The mechanistic target of the rapamycin (mTOR) pathway plays a role in features common to both excess salt/aldosterone and cardiovascular/renal diseases. Dietary sodium can upregulate mTORC1 signaling in cardiac and renal tissue, and the inhibition of mTOR can prevent aldosterone-associated, salt-induced hypertension. The impact of sex and age on mTOR's role in volume homeostasis and the regulation of aldosterone secretion is largely unknown. We hypothesize that both age and sex modify mTOR's interaction with volume homeostatic mechanisms. The activity of 3 volume homeostatic mechanisms-cardiovascular, renal, and hormonal (aldosterone [sodium retaining] and brain natriuretic peptide [BNP; sodium losing])-were assessed in mTORC1 deficient (Raptor+/-) and wild-type male and female littermates at 2 different ages. The mice were volume stressed by being given a liberal salt (LibS) diet. Raptor+/-mice of both sexes when they aged: (1) reduced their blood pressure, (2) increased left ventricular internal diameter during diastole, (3) decreased renal blood flow, and (4) increased mineralocorticoid receptor expression. Aldosterone levels did not differ by sex in young Raptor+/- mice. However, as they aged, compared to their littermates, aldosterone decreased in males but increased in females. Finally, given the level of Na+ intake, BNP was inappropriately suppressed, but only in Raptor+/- males. These data indicate that Raptor+/- mice, when stressed with a LibS diet, display inappropriate volume homeostatic responses, particularly with aging, and the mechanisms altered, differing by sex.

Primary Aldosteronism Decreases Insulin Secretion and Increases Insulin Clearance in Humans

Primary aldosteronism is a frequent cause of resistant hypertension and is associated with an increased risk of developing diabetes mellitus. Aldosterone impairs insulin secretion in isolated islets, and insulin secretion is increased in aldosterone synthase-deficient mice. We hypothesized that treatment for primary aldosteronism increases insulin secretion and insulin sensitivity in humans. We conducted a prospective cohort study in patients with primary aldosteronism, with assessment of glucose metabolism before and 3 to 12 months after treatment. Participants underwent treatment for primary aldosteronism with adrenalectomy or a mineralocorticoid receptor antagonist at the discretion of their treating physician. We assessed insulin secretion and insulin sensitivity by hyperglycemic and hyperinsulinemic-euglycemic clamps, respectively, on 2 study days after a 5-day standardized diet. After treatment, the C-peptide and insulin response during the hyperglycemic clamp increased compared with pretreatment (ΔC-peptide at 90-120 minutes +530.5±384.1 pmol/L, P=0.004; Δinsulin 90-120 minutes +183.0±122.6, P=0.004). During hyperinsulinemic-euglycemic clamps, insulin sensitivity decreased after treatment (insulin sensitivity index 30.7±6.2 versus 18.5±4.7 nmol·kg^-1·min^-1·pmol^-1·L; P=0.02). Insulin clearance decreased after treatment (872.8±207.6 versus 632.3±178.6 mL/min; P=0.03), and disposition index was unchanged. We conclude that the insulin response to glucose increases and insulin clearance decreases after treatment for primary aldosteronism, and these effects were not due to alterations in creatinine clearance or plasma cortisol. These studies may provide further insight into the mechanism of increased diabetes mellitus risk in primary aldosteronism.

Impact of circadian disruption on glucose metabolism: implications for type 2 diabetes

The circadian system generates endogenous rhythms of approximately 24 h, the synchronisation of which are vital for healthy bodily function. The timing of many physiological processes, including glucose metabolism, are coordinated by the circadian system, and circadian disruptions that desynchronise or misalign these rhythms can result in adverse health outcomes. In this review, we cover the role of the circadian system and its disruption in glucose metabolism in healthy individuals and individuals with type 2 diabetes mellitus. We begin by defining circadian rhythms and circadian disruption and then we provide an overview of circadian regulation of glucose metabolism. We next discuss the impact of circadian disruptions on glucose control and type 2 diabetes. Given the concurrent high prevalence of type 2 diabetes and circadian disruption, understanding the mechanisms underlying the impact of circadian disruption on glucose metabolism may aid in improving glycaemic control.

Sex-specific differences in endoplasmic reticulum aminopeptidase 1 modulation influence blood pressure and renin-angiotensin system responses

Salt sensitivity of blood pressure (SSBP) and hypertension are common, but the underlying mechanisms remain unclear. Endoplasmic reticulum aminopeptidase 1 (ERAP1) degrades angiotensin II (ANGII). We hypothesized that decreasing ERAP1 increases BP via ANGII-mediated effects on aldosterone (ALDO) production and/or renovascular function. Compared with WT littermate mice, ERAP1-deficient (ERAP1+/-) mice had increased tissue ANGII, systolic and diastolic BP, and SSBP, indicating that ERAP1 deficiency leads to volume expansion. However, the mechanisms underlying the volume expansion differed according to sex. Male ERAP1+/- mice had increased ALDO levels and normal renovascular responses to volume expansion (decreased resistive and pulsatility indices and increased glomerular volume). In contrast, female ERAP1+/- mice had normal ALDO levels but lacked normal renovascular responses. In humans, ERAP1 rs30187, a loss-of-function gene variant that reduces ANGII degradation in vitro, is associated with hypertension. In our cohort from the Hypertensive Pathotype (HyperPATH) Consortium, there was a significant dose-response association between rs30187 risk alleles and systolic and diastolic BP as well as renal plasma flow in men, but not in women. Thus, lowering ERAP1 led to volume expansion and increased BP. In males, the volume expansion was due to elevated ALDO with normal renovascular function, whereas in females the volume expansion was due to impaired renovascular function with normal ALDO levels.

Higher urinary cortisol levels associate with increased cardiovascular risk

There are conflicting data on whether variations of physiologic cortisol levels associated with cardiovascular risk. We hypothesize that prior discordant findings are related to problems associated with varying sample size, techniques for assessing cardiovascular risk and failure to adequately account for environmental factors. To address these issues, we utilized a large sample size, selected the Framingham risk score to compute cardiovascular risk and performed the study in a highly controlled setting. We had two main objectives: determine whether higher, yet physiologic, cortisol levels associated with increased cardiovascular risk and determine whether caveolin-1 (rs926198) risk allele carriers associated with increased cardiovascular risk. This was a cross-sectional study of 574 non-diabetic individuals who completed a common protocol. Data collection included fasting blood samples, blood pressure measurements and a 24-h urine-free cortisol collection. Five hundred seventeen of these participants also completed caveolin-1 genotyping. Subjects were classified as belonging to either the low-mode or high-mode urine-free cortisol groups, based on the bimodal distribution of urine-free cortisol. In multivariate analysis, Framingham risk score was statistically higher in the high-mode cortisol group (10.22 (mean) ± 0.43 (s.e.m.)) compared to the low-mode cortisol group (7.73 ± 0.34), P < 0.001. Framingham risk score was also statistically higher in the caveolin-1 risk allele carriers (8.91 ± 0.37) compared to caveolin-1 non-risk allele carriers (7.59 ± 0.48), P = 0.034. Overall, the estimated effect on Framingham risk score of carrying the caveolin-1 risk allele was 1.33 ± 0.61, P = 0.029. Both urinary cortisol and caveolin-1 risk allele status are independent predictors of Framingham risk score.

Aldosterone Modulates the Mechanistic Target of Rapamycin Signaling in Male Mice

Both mechanistic target of rapamycin (mTOR) pathway and aldosterone are implicated in the development of cardiovascular and renal disease. However, the interaction between aldosterone and the mTOR pathway is unknown. We hypothesized the following: that (i) increased aldosterone will modulate the activity of the mTORC1 and mTORC2 molecular pathways in the heart and kidney; (ii) a physiologic increase in aldosterone will affect these pathways differently than a pathophysiologic one; and (iii) the changes in the mTOR level/activity will differ between the heart and kidney. In both kidney and heart tissues, phosphorylation of mTOR is significantly decreased when aldosterone levels are physiologically increased (by dietary sodium restriction), followed by a decrease in phosphorylated p70S6K1 in cardiac, but not renal, tissue. Sirtuin 1, an epigenetic modulator, is decreased in the heart but increased in the kidney. Conversely, pathophysiologic aldosterone levels (an infusion for 3 weeks) had divergent effects on phosphorylated mTOR and the downstream substrates of mTORC1 and mTORC2 in cardiac and renal tissues. Increased aldosterone levels significantly alter mTOR activity in the heart and kidney. In the kidney, substantial differences were noted if the increase was produced physiologically vs pathophysiologically, suggesting that mTOR activity, in part, may mediate aldosterone-induced renal damage. Thus, modulating mTOR activity may reduce aldosterone-dependent renal damage similar to mineralocorticoid receptor blockade but potentially with less adverse side effects.

Sex Differences in Coronary Microvascular Function in Individuals With Type 2 Diabetes

Cardiovascular (CV) disease fatality rates are higher for women compared with men with diabetes despite lower rates of obstructive coronary artery disease (CAD). Impaired coronary flow reserve (CFR), the ratio of adenosine-stimulated to rest myocardial blood flow (MBF), is an indicator of coronary microvascular dysfunction and predicts major adverse CV events. We performed a post hoc analysis to determine whether there was a sex disparity in coronary microvascular dysfunction among 46 men and 27 women with well-controlled type 2 diabetes and without clinical evidence of obstructive CAD. We found that women had a higher rest MBF, lower CFR, and worse diastolic function compared with men. In addition, rest MBF was positively correlated with worse diastolic function in women. We previously showed that mineralocorticoid blockade improved CFR in men and women with type 2 diabetes, implicating aldosterone in the pathophysiology of coronary microvascular dysfunction. We therefore examined aldosterone levels and found that women had larger increases in aldosterone in response to an angiotensin-II infusion than did men. In conclusion, among individuals with type 2 diabetes and good cardiometabolic control, women had worse myocardial perfusion and diastolic function compared with men. The greater aldosterone responsivity in women may be a mechanism for this sex effect.

Histone demethylase LSD1 deficiency and biological sex: impact on blood pressure and aldosterone production

Human risk allele carriers of lysine-specific demethylase 1 (LSD1) and LSD1-deficient mice have salt-sensitive hypertension for unclear reasons. We hypothesized that LSD1 deficiency causes dysregulation of aldosterone's response to salt intake resulting in increased cardiovascular risk factors (blood pressure and microalbumin). Furthermore, we determined the effect of biological sex on these potential abnormalities. To test our hypotheses, LSD1 male and female heterozygote-knockout (LSD1+/-) and WT mice were assigned to two age groups: 18 weeks and 36 weeks. Plasma aldosterone levels and aldosterone production from zona glomerulosa cells studied ex vivo were greater in both male and female LSD1+/- mice consuming a liberal salt diet as compared to WT mice consuming the same diet. However, salt-sensitive blood pressure elevation and increased microalbuminuria were only observed in male LSD1+/- mice. These data suggest that LSD1 interacts with aldosterone's secretory response to salt intake. Lack of LSD1 causes inappropriate aldosterone production on a liberal salt diet; males appear to be more sensitive to this aldosterone increase as males, but not females, develop salt sensitivity of blood pressure and increased microalbuminuria. The mechanism responsible for the cardiovascular protective effect in females is uncertain but may be related to estrogen modulating the effect of mineralocorticoid receptor activation.

The Expanding Spectrum of Primary Aldosteronism: Implications for Diagnosis, Pathogenesis, and Treatment

Primary aldosteronism is characterized by aldosterone secretion that is independent of renin and angiotensin II and sodium status. The deleterious effects of primary aldosteronism are mediated by excessive activation of the mineralocorticoid receptor that results in the well-known consequences of volume expansion, hypertension, hypokalemia, and metabolic alkalosis, but it also increases the risk for cardiovascular and kidney disease, as well as death. For decades, the approaches to defining, diagnosing, and treating primary aldosteronism have been relatively constant and generally focused on detecting and treating the more severe presentations of the disease. However, emerging evidence suggests that the prevalence of primary aldosteronism is much greater than previously recognized, and that milder and nonclassical forms of renin-independent aldosterone secretion that impart heightened cardiovascular risk may be common. Public health efforts to prevent aldosterone-mediated end-organ disease will require improved capabilities to diagnose all forms of primary aldosteronism while optimizing the treatment approaches such that the excess risk for cardiovascular and kidney disease is adequately mitigated. In this review, we present a physiologic approach to considering the diagnosis, pathogenesis, and treatment of primary aldosteronism. We review evidence suggesting that primary aldosteronism manifests across a wide spectrum of severity, ranging from mild to overt, that correlates with cardiovascular risk. Furthermore, we review emerging evidence from genetic studies that begin to provide a theoretical explanation for the pathogenesis of primary aldosteronism and a link to its phenotypic severity spectrum and prevalence. Finally, we review human studies that provide insights into the optimal approach toward the treatment of primary aldosteronism.

Oxytocin response to controlled dietary sodium and angiotensin II among healthy individuals

Oxytocin, while classically known for its role in parturition, lactation, and social behavior, also has been implicated in the control of sodium homeostasis in animal models. To improve our understanding of oxytocin physiology in humans, we measured basal oxytocin levels under low- and liberal-dietary-sodium conditions and following a peripheral angiotensin II (ANG II) infusion. Ten healthy individuals underwent a 6-day standardized low-sodium diet and a 6-day liberal-sodium diet. Each diet was followed by a graded ANG II infusion for 30-min sequential intervals at doses of 0.3, 1.0, and 3.0 ng·kg^-1·min^-1. Fasting serum oxytocin was assessed before and after ANG II infusion. Basal oxytocin levels (1,498.5 ± 94.7 vs. 1,663.3 ± 213.9 pg/ml, P = 0.51) did not differ after the low- and liberal-sodium diets. Following the ANG II infusion, ANG II levels and mean arterial pressure significantly increased as expected. In contrast, the ANG II infusion significantly lowered oxytocin levels from 1,498.5 ± 94.7 vs. 1,151.7 ± 118.1 pg/ml ( P < 0.001) on the low-sodium diet and from 1,663.3 ± 213.9 vs. 1,095.2 ± 87.4 pg/ml ( P = 0.03) on the liberal-sodium diet. The percent change in oxytocin following the ANG II infusion did not differ by sodium diet (-25 ± 5% vs. -28 ± 7% low- vs. liberal-sodium conditions, P > 0.99). Dietary sodium intake did not affect circulating oxytocin levels among healthy individuals. Systemic oxytocin levels were significantly suppressed following a peripheral ANG II infusion independent of dietary sodium conditions.

A randomized intervention study to evaluate the effect of calcitriol therapy on the renin-angiotensin system in diabetes

Background:

Prior studies suggest that vitamin D therapy may decrease cardiovascular disease risk in type 2 diabetes (T2DM) by lowering renin-angiotensin system (RAS) activity. However, randomized human intervention studies to evaluate the effect of vitamin D receptor (VDR) agonists on RAS activity are lacking.

Objective:

The objective of this article is to investigate the effect of direct VDR activation with calcitriol on circulating RAS activity and vascular hemodynamics in T2DM.

Methods:

A randomized, double-blinded, and placebo-controlled study wherein 18 participants with well-controlled T2DM without chronic kidney disease (CKD) were administered calcitriol or placebo for three weeks was conducted. Outcome measures included plasma renin activity (PRA), serum and urinary aldosterone, mean arterial pressure (MAP) before and after an infusion of angiotensin II, and renal plasma flow (RPF) via para-aminohippurate clearance.

Results:

Despite an increase in 1,25(OH)₂D with calcitriol administration (45.4 to 61.8 pg/ml, p = 0.03) and no change with placebo, there were no significant differences in PRA, serum or urinary aldosterone, baseline and angiotensin II-stimulated MAP, or basal and angiotensin II-stimulated RPF between interventions.

Conclusion:

In this randomized and placebo-controlled study in participants with T2DM without CKD, calcitriol therapy to raise 1,25(OH)₂D levels, when compared with placebo, did not significantly change circulating RAS activity or vascular hemodynamics.

Significant Association of Aldosterone and Liver Fat Among HIV-Infected Individuals With Metabolic Dysregulation

Objective

Fatty liver disease is increased among individuals with HIV. We sought to explore how aldosterone, a key hormone linked to insulin resistance and inflammation, relates to liver fat in the large population of individuals with HIV and metabolic abnormalities.

Methods

Forty-six individuals with HIV and increased waist circumference and dysglycemia were assessed for liver fat using proton magnetic resonance spectroscopy. Serum aldosterone level was obtained following strictly controlled posture conditions and a standardized sodium diet and was related to liver fat.

Results

Among the entire group [median (interquartile range) liver fat: 5% (3%, 12%) and homeostatic model assessment of insulin resistance: 1.74 (1.21, 2.83)], serum aldosterone significantly correlated with liver fat (r = 0.31; P = 0.049). Liver fat level was significantly higher in those with aldosterone above vs below the median [8% (3%, 20%) vs 4% (2%, 10%); P = 0.02]. In the presence of metabolic syndrome, individuals with aldosterone levels above vs below the median had markedly elevated liver fat values [14% (9%, 23%) vs 5% (3%, 12%); P = 0.005] and increased presence of fatty liver disease (FLD; 92% vs 50%; P = 0.02). Controlling for metabolic syndrome, hepatitis C virus, and alcohol use, aldosterone was a significant and independent predictor of liver fat (β estimate: 0.6038, P = 0.01; overall model r² = 0.41, P = 0.0005) and FLD (OR: 1.38, P = 0.02; overall model r² = 0.28, P = 0.002).

Conclusion

These data highlight a robust association between aldosterone and liver fat among individuals with HIV and metabolic dysregulation. Increased aldosterone may be a risk factor for liver fat accumulation among the population with HIV.

Caloric restriction improves glucose homeostasis, yet increases cardiometabolic risk in caveolin-1-deficient mice

BACKGROUND AND PURPOSE

The plasma membrane protein caveolin-1 (CAV-1) has been shown to be involved in modulating glucose homeostasis and the actions of the renin-angiotensin-aldosterone system (RAAS). Caloric restriction (CR) is widely accepted as an effective therapeutic approach to improve insulin sensitivity and reduce the severity of diabetes. Recent data indicate that polymorphisms of the CAV-1 gene are strongly associated with insulin resistance, hypertension and metabolic abnormalities in non-obese individuals. Therefore, we sought to determine whether CR improves the metabolic and cardiovascular (CV) risk factors in the lean CAV-1 KO mice.

MATERIALS/METHODS

Twelve- to fourteen-week-old CAV-1 knockout (KO) and genetically matched wild-type (WT) male mice were randomized by genotype to one of two dietary regimens: ad libitum (ad lib) food intake or 40% CR for 4 weeks. Three weeks following the onset of dietary restriction, all groups were assessed for insulin sensitivity. At the end of the study, all groups were assessed for fasting glucose, insulin, HOMA-IR, lipids, corticosterone levels and blood pressure (BP). Aldosterone secretion was determined from acutely isolated Zona Glomerulosa cells.

RESULTS

We confirmed that the CAV-1 KO mice on the ad lib diet display a phenotype consistent with the cardiometabolic syndrome, as shown by higher systolic BP (SBP), plasma glucose, HOMA-IR and aldosterone levels despite lower body weight compared with WT mice on the ad lib diet. CAV-1 KO mice maintained their body weight on the ad lib diet, but had substantially greater weight loss with CR, as compared to caloric restricted WT mice. CR-mediated changes in weight were associated with dramatic improvements in glucose and insulin tolerance in both genotypes. These responses to CR, however, were more robust in CAV-1KO vs. WT mice and were accompanied by reductions in plasma glucose, insulin and HOMA-IR in CAV-1KO but not WT mice. Surprisingly, in the CAV-1 KO, but not in WT mice, CR was associated with increased SBP and aldosterone levels, suggesting that in CAV-1 KO mice CR induced an increase in some CV risk factors.

CONCLUSIONS

CR improved the metabolic phenotype in CAV-1 KO mice by increasing insulin sensitivity; nevertheless, this intervention also increased CV risk by inappropriate adaptive responses in the RAAS and BP.

Randomized, Placebo-Controlled Trial to Evaluate Effects of Eplerenone on Metabolic and Inflammatory Indices in HIV

CONTEXT

HIV-infected individuals demonstrate increased renin-angiotensin-aldosterone system activation in association with visceral adiposity, insulin resistance, and inflammation. A physiologically based treatment approach targeting mineralocorticoid receptor (MR) blockade may improve metabolic and inflammatory indices in HIV.

OBJECTIVE

To investigate effects of eplerenone on insulin sensitivity, inflammatory indices, and other metabolic parameters in HIV.

DESIGN

Six-month, double-blind, randomized, placebo-controlled trial.

SETTING

Academic clinical research center.

PARTICIPANTS

HIV-infected individuals with increased waist circumference and abnormal glucose homeostasis.

INTERVENTION

Eplerenone 50 mg or placebo daily.

OUTCOME

The primary end point was change in insulin sensitivity measured by the euglycemic-hyperinsulinemic clamp technique. Secondary end points included change in body composition and inflammatory markers.

RESULTS

Forty-six individuals were randomized to eplerenone (n = 25) vs placebo (n = 21). Eplerenone did not improve insulin sensitivity [0.48 (-1.28 to 1.48) vs 0.43 (-1.95 to 2.55) mg/min/μIU/mL insulin; P = 0.71, eplerenone vs placebo] when measured by the gold standard euglycemic-hyperinsulinemic clamp technique. Intramyocellular lipids (P = 0.04), monocyte chemoattractant protein-1 (P = 0.04), and high-density lipoprotein (P = 0.04) improved among those randomized to eplerenone vs placebo. Trends toward decreases in interleukin-6 (P = 0.10) and high-sensitivity C-reactive protein (P = 0.10) were also seen with eplerenone vs placebo. Plasma renin activity and aldosterone levels increased in the eplerenone vs placebo-treated group, demonstrating expected physiology. MR antagonism with eplerenone was well tolerated among the HIV population, with no considerable changes in blood pressure or potassium.

CONCLUSION

MR blockade may improve selected metabolic and inflammatory indices in HIV-infected individuals. Further studies are necessary to understand the clinical potential of MR antagonism in HIV.

Biological Sex Modulates the Adrenal and Blood Pressure Responses to Angiotensin II

The relationship between biological sex and aldosterone on blood pressure (BP) is unclear. We hypothesized that sex would modify the interaction between aldosterone and vascular responses to salt intake and angiotensin II (AngII). To test this hypothesis, in 1592 subjects from the well-controlled Hypertensive Pathotype cohort, we compared responses of women and men to chronic (BP and aldosterone levels in response to dietary salt) and acute (BP, renal plasma flow, and aldosterone responses to AngII infusion) manipulations. Women had a 30% higher salt sensitivity of BP than men (P<0.0005) regardless of age or hypertension status, a greater BP response to AngII, and a 15% greater aldosterone response to AngII on both restricted and liberal salt diets (P<0.005). Furthermore, there was an interaction (P=0.003) between sex and aldosterone on BP response to AngII. Women also had a greater (P<0.01) increment in renal plasma flow in response to AngII than men. To assess potential mechanisms for this sex effect, we compared aldosterone responses to AngII or potassium from rat zona glomerulosa cells and observed greater aldosterone production in female than male zona glomerulosa cells basally and in response to both agonists (P<0.0001). In a rodent model of aldosterone-mediated cardiovascular disease induced by increased AngII and low NO, circulating aldosterone levels (P<0.01), myocardial damage (P<0.001), and proteinuria (P<0.05) were greater in female than male rats despite having similar BP responses. Thus, increased aldosterone production likely contributes to sex differences in cardiovascular disease, suggesting that women may be more responsive to mineralocorticoid receptor blockade than men.

Excessive Adiposity and Metabolic Dysfunction Relate to Reduced Natriuretic Peptide During RAAS Activation in HIV

PURPOSE

Natriuretic peptides (NPs) negatively feedback on the renin-angiotensin-aldosterone system (RAAS) and play a critical role in preserving cardiac structure and maintaining metabolic homeostasis. Well-treated HIV-infected individuals are at risk for fat redistribution and demonstrate evidence of RAAS dysregulation, which relates to metabolic dysfunction. We investigated circulating NPs in relation to RAAS physiology and metrics of body composition in HIV.

METHODS

We assessed atrial natriuretic peptide, brain natriuretic peptide (BNP), and amino terminal pro B-type natriuretic peptide (NT-proBNP) during acute activation of the RAAS using a low-sodium controlled diet among 20 HIV-infected and 10 non-HIV-infected individuals well phenotyped for body composition.

RESULTS

BNP was significantly lower [median, 60 (interquartile range, 44, 152) pg/mL vs 196 (91, 251) pg/mL, respectively; P = 0.04], and serum aldosterone was higher, among HIV-infected than among non-HIV-infected individuals. BNP was significantly and inversely associated with body composition [waist circumference: r = -0.46 (P = 0.04); BMI: r = -0.55 (P = 0.01); body adiposity index: r = -0.49 (P = 0.03)], metabolic indices [total cholesterol: r = -0.44 (P = 0.05), insulin resistance calculated by using homeostatic model assessment: r = -0.44 (P = 0.05); mean arterial pressure: r = -0.44 (P = 0.05)], and serum aldosterone (r = -0.49; P = 0.03) among the HIV-infected group. These relationships were not demonstrated in the non-HIV-infected group. In a four-group comparison stratifying by HIV serostatus and above or below a body mass index (BMI) of 25 kg/m2, BNP decreased significantly across groups; it was highest in non-HIV-infected patients with a BMI <25 kg/m2 and lowest in HIV-infected patients with a BMI ≥25 kg/m2 (overall P = 0.01).

CONCLUSION

Relatively reduced NP, particularly BNP, among HIV-infected individuals with excess adiposity may contribute to reduced suppression of aldosterone and potentially drive aldosterone-mediated metabolic complications. Strategies that target RAAS blockade and/or augment NPs may be useful to reduce cardiometabolic disease among HIV-infected individuals in whom these systems are perturbed.