Understanding sex differences in long-term blood pressure regulation: insights from experimental studies and computational modeling

Mineralocorticoid Receptor and Aldosterone: Interaction Between NR3C2 Genetic Variants, Sex, and Age in a Mixed Cohort

CONTEXT

Hypertension, a prevalent cardiovascular risk, often involves dysregulated aldosterone and its interaction with the mineralocorticoid receptor (MR). Experimental designs in animal models and human cohorts have demonstrated a sex and age dependency of aldosterone secretion that expands our pathophysiologic understanding.

OBJECTIVE

This study explores the genetic variation of NR3C2, which encodes MR, in relation to aldosterone, considering age, sex, and race.

METHODS

Incorporating 720 Caucasians and 145 Africans from the HyperPATH cohort, we investigated the impact of rs4835490, a single nucleotide risk allele variant, on aldosterone levels and vasculature.

RESULTS

Notably, a significant association between rs4835490 and plasma aldosterone under liberal salt conditions emerged in individuals of European ancestry (P = .0002). Homozygous carriers of the risk A allele exhibited elevated plasma aldosterone levels (AA = 8.1 ± .9 vs GG = 4.9 ± .5 ng/dL). Additionally, aldosterone activation through posture (P = .025) and urinary excretion (P = .0122) showed notable associations. Moreover, genetic interactions with race, sex, and age were observed. Caucasian females under 50 years displayed higher plasma aldosterone, urine aldosterone, and posture aldosterone with the AA genotype compared to females over 50 years, suggesting a potential connection with menopausal or estrogen influences. Interestingly, such age-dependent interactions were absent in the African cohort.

CONCLUSION

Our study highlights the significance of the NR3C2 genetic variation and its interplay with age, sex, and race in aldosterone activation. The findings point toward an estrogen-modulating effect on MR activation, particularly in women, underlining the role of aldosterone dysregulation in hypertension development. This insight advances our comprehension of hypertension's complexities and opens avenues for personalized interventions. Clinical Trial Registration Number: NCT03029806 (registered January 24, 2017).

Salt-Responsive Gut Microbiota Induces Sex-Specific Blood Pressure Changes

BACKGROUND

Tryptophan metabolism is important in blood pressure regulation. The tryptophan-indole pathway is exclusively mediated by the gut microbiota. ACE2 (angiotensin-converting enzyme 2) participates in tryptophan absorption, and a lack of ACE2 leads to changes in the gut microbiota. The gut microbiota has been recognized as a regulator of blood pressure. Furthermore, there is ample evidence for sex differences in the gut microbiota. However, it is unclear whether such sex differences impact blood pressure differentially through the tryptophan-indole pathway.

METHODS

To study the sex-specific mechanisms of gut microbiota-mediated tryptophan-indole pathway in hypertension, we generated a novel rat model with Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats-associated protein 9)-targeted deletion of Ace2 in the Dahl salt-sensitive rat. Cecal microbiota transfers from donors of both sexes to female S recipients were performed. Also, Dahl salt-sensitive rats of both sexes were orally gavaged with indole to investigate blood pressure response.

RESULTS

The female gut microbiota and its tryptophan-indole pathway exhibited greater buffering capacity when exposed to tryptophan, due to Ace2 deficiency, and salt. In contrast, the male gut microbiota and its tryptophan-indole pathway were more vulnerable. Female rats with male cecal microbiota responded to salt with a higher blood pressure increase compared with those with female cecal microbiota. Indole, a tryptophan-derived metabolite produced by gut bacteria, increased blood pressure in male but not in female rats. Moreover, salt altered host-mediated tryptophan metabolism, characterized by reduced serum serotonin of both sexes and higher levels of kynurenine derivatives in the females.

CONCLUSIONS

We uncovered a novel sex-specific mechanism in the gut microbiota-mediated tryptophan-indole pathway in blood pressure regulation. Salt tipped the tryptophan metabolism between the host and gut microbiota in a sex-dependent manner. Our study provides evidence for a novel concept that gut microbiota and its metabolism play sex-specific roles in the development of salt-sensitive hypertension.

We are all different: Modeling key individual differences in physiological systems

Mathematical models of whole-body dynamics have advanced our understanding of human integrative systems that regulate physiological processes such as metabolism, temperature, and blood pressure. For most of these whole-body models, baseline parameters describe a 35-year-old young adult man who weighs 70 kg. As such, even among adults those models may not accurately represent half of the population (women), the older population, and those who weigh significantly more than 70 kg. Indeed, sex, age, and weight are known modulators of physiological function. To more accurately simulate a person who does not look like that "baseline person," or to explain the mechanisms that yield the observed sex or age differences, these factors should be incorporated into mathematical models of physiological systems. Another key modulator is the time of day, because most physiological processes are regulated by the circadian clocks. Thus, ideally, mathematical models of integrative physiological systems should be specific to either a man or woman, of a certain age and weight, and a given time of day. We illustrate the importance of capturing these individual differences, using the blood pressure regulatory system as an example, and explain how that such models can be built.

A modeling analysis of whole body potassium regulation on a high-potassium diet: proximal tubule and tubuloglomerular feedback effects

Potassium (K+) is an essential electrolyte that plays a key role in many physiological processes, including mineralcorticoid action, systemic blood-pressure regulation, and hormone secretion and action. Indeed, maintaining K+ balance is critical for normal cell function, as too high or too low K+ levels can have serious and potentially deadly health consequences. K+ homeostasis is achieved by an intricate balance between the intracellular and extracellular fluid as well as balance between K+ intake and excretion. This is achieved via the coordinated actions of regulatory mechanisms such as the gastrointestinal feedforward effect, insulin and aldosterone upregulation of Na+-K+-ATPase uptake, and hormone and electrolyte impacts on renal K+ handling. We recently developed a mathematical model of whole body K+ regulation to unravel the individual impacts of these regulatory mechanisms. In this study, we extend our mathematical model to incorporate recent experimental findings that showed decreased fractional proximal tubule reabsorption under a high-K+ diet. We conducted model simulations and sensitivity analyses to investigate how these renal alterations impact whole body K+ regulation. Model predictions quantify the sensitivity of K+ regulation to various levels of proximal tubule K+ reabsorption adaptation and tubuloglomerular feedback. Our results suggest that the reduced proximal tubule K+ reabsorption under a high-K+ diet could achieve K+ balance in isolation, but the resulting tubuloglomerular feedback reduces filtration rate and thus K+ excretion.NEW & NOTEWORTHY Potassium homeostasis is maintained in the body by a complex system of regulatory mechanisms. This system, when healthy, maintains a small extracellular potassium concentration, despite large fluctuations of dietary potassium. The complexities of the system make this problem well suited for investigation with mathematical modeling. In this study, we extend our mathematical model to consider recent experimental results on renal potassium handling on a high potassium diet and investigate the impacts from a whole body perspective.

The long and the short of it: Salivary telomere length as a candidate biomarker for hypertension and age-related changes in blood pressure

Hypertension becomes more prevalent with increasing age. Telomere length (TL) has been proposed as a candidate biomarker and can be accessibly extracted from saliva. However, clarity is needed to evaluate the suitability of using TL as a predictor in such instances. This study investigated salivary TL in a cohort of older adults from the 2008 Health and Retirement Study (n = 3329; F: 58%, mean age: 69.4, SD: 10.3 years) to examine any associations with blood pressure (BP). A Bayesian robust regression model was fit using weakly informative priors to predict the effects of TL with age, sex, systolic BP (SBP), diastolic BP (DBP), and treatment status. There were small effects of treatment (β: -0.07, 95% CrI [-0.33, 0.19], pd: 71.91%) and sex (β: -0.10, 95% CrI [-0.27, 0.07], pd: >86.78%). Population effects showed a reduction of 0.01 log2 units in TL with each year of advancing age (95% CrI [-0.01, -0.00]). Conditional posterior predictions suggest that females, and treated individuals, experience greater change in TL with increasing age. Bayes R2 was ~2%. TL declines with increasing age, differs between sexes, and appears to be influenced by antihypertensive drugs. Overall, all effects were weak. The data do not currently support the suitability of salivary TL as a biomarker to predict or understand any age-related changes in BP.

MicroRNA-19 is regulated by aldosterone in a sex-specific manner to alter kidney sodium transport

A key regulator of blood pressure homeostasis is the steroid hormone aldosterone, which is released as the final signaling hormone of the renin-angiotensin-aldosterone-signaling (RAAS) system. Aldosterone increases sodium (Na+) reabsorption in the kidney distal nephron to regulate blood volume. Unregulated RAAS signaling can lead to hypertension and cardiovascular disease. The serum and glucocorticoid kinase (SGK1) coordinates much of the Na+ reabsorption in the cortical collecting duct (CCD) tubular epithelial cells. We previously demonstrated that aldosterone alters the expression of microRNAs (miRs) in CCD principal cells. The aldosterone-regulated miRs can modulate Na+ transport and the cellular response to aldosterone signaling. However, the sex-specific regulation of miRs by aldosterone in the kidney distal nephron has not been explored. In this study, we report that miR-19, part of the miR-17-92 cluster, is upregulated in female mouse CCD cells in response to aldosterone activation. Mir-19 binding to the 3'-untranslated region of SGK1 was confirmed using a dual-luciferase reporter assay. Increasing miR-19 expression in CCD cells decreased SGK1 message and protein expression. Removal of this cluster using a nephron-specific, inducible knockout mouse model increased SGK1 expression in female mouse CCD cells. The miR-19-induced decrease in SGK1 protein expression reduced the response to aldosterone stimulation and may account for sex-specific differences in aldosterone signaling. By examining evolution of the miR-17-92 cluster, phylogenetic sequence analysis indicated that this cluster arose at the same time that other Na+-sparing and salt regulatory proteins, specifically SGK1, first emerged, indicating a conserved role for these miRs in kidney function of salt and water homeostasis.NEW & NOTEWORTHY Expression of the microRNA-17-92 cluster is upregulated by aldosterone in mouse cortical collecting duct principal cells, exclusively in female mice. MiR-19 in this cluster targets the serum and glucocorticoid kinase (SGK1) to downregulate both mRNA and protein expression, resulting in a decrease in sodium transport across epithelial cells of the collecting duct. The miR-17-92 cluster is evolutionarily conserved and may act as a novel feedback regulator for aldosterone signaling in females.

Oat Beta-Glucan Alone and in Combination with Hydrochlorothiazide Lowers High Blood Pressure in Male but Not Female Spontaneously Hypertensive Rats

Oats are considered a functional food due to the beneficial health effects associated with their consumption and are suitable to be explored for their ability to prevent or manage chronic disease, such as hypertension. Here, we examined the cardiovascular benefits of an oat beta-glucan extract in male and female spontaneously hypertensive rats (SHRs) to unravel its sex-specific roles when used with an anti-hypertensive medication, hydrochlorothiazide. Five-week-old male and female SHRs and Wistar-Kyoto (WKY) rats were treated with oat beta-glucan and hydrochlorothiazide for 15 weeks. Twenty-week-old male and female SHRs showed high blood pressure (BP), cardiac remodeling, and cardiac dysfunction. These animals also had significantly increased levels of malondialdehyde (MDA), angiotensin II, and norepinephrine. Treatments with beta-glucan and hydrochlorothiazide were able to differentially prevent high BP, cardiac dysfunction, and alterations in malondialdehyde (MDA), angiotensin II, and norepinephrine in 20-week-old male and female SHRs. To conclude, beta-glucan alone and in combination with hydrochlorothiazide may be a promising a strategy for managing hypertension and related cardiac complications.

Possibilities of Interpreting the Night-to-Day Ratio Specified by 24-Hour Blood Pressure Monitoring

Aim

Specify the risk rate of incorrect patient classification based on the night-to-day ratio specification from singular 24-h ABPM in comparison to the results of 7-day ABPM monitoring.

Materials and Methods

1197 24 h cycles were enrolled in 171 subjects in the study and divided into 4 groups: group 1 (40 healthy men and women without exercise), group 2 (40 healthy exercise-training men and women), group 3 (40 patients with ischemic coronary artery disease without exercise), and group 4 (51 patients with ischemic coronary artery disease following cardiovascular rehabilitation). The subject of the evaluation was the percentage rate of incorrect subject classification (dipper, nondipper, extreme dipper, and riser) based on the mean blood pressure values for 7 days and from seven independent 24-hour cycles (the mean value mode).

Results

In the case of the individuals included in the monitored groups, the mean night-to-day ratio-based (mode for the 7 days versus the individual days of 24-hour monitoring) classification accordance ranged between 59% and 62%. Only in singular cases did the accordance reach 0% or 100%. The accordance size was not dependent on the health or cardiovascular disease (p < 0.594; 56% vs. 54%) or physical activity (p < 0.833; 55% vs. 54%) of the monitored individuals.

Conclusion

The specification of the night-to-day ratio of each individual for each day of the 7-day ABPM monitoring would be the most convenient option. In many patients, diagnosing could thus be based on the most frequently occurring values (mode specification).

Sex differences in hypertension among people living with HIV after initiation of antiretroviral therapy

Background

Hypertension is common in people living with HIV (PLWH) on antiretroviral therapy (ART). In the general population and in experimental animal models, the incidence of hypertension is greater in males than in females, especially during the premenopausal period. However, it is not known whether there are sex differences in hypertension associated with HIV and ART, and the factors contributing to incident hypertension among PLWH have not been well characterized. In this study, we aimed to determine the time course, sex differences and factors associated with incident hypertension in PLWH initiating ART.

Methods and results

We conducted a retrospective study in which we used programmatic data from the ART registry to identify sex differences in the determinants of incident hypertension among PLWH initiating the ART regimen from Livingstone University Teaching Hospital in Zambia and followed for 8 years. Males developed hypertension earlier, 2 years after initiating ART, compared to 6 years in females. In multivariable analysis, increasing age, baseline systolic blood pressure and baseline mean arterial pressure (MAP) were associated with increased risk for developing incident hypertension. Also, participants who switched to the integrase strand transfer inhibitor, dolutegravir (DTG) or the protease inhibitor, lopinavir boosted with ritonavir were 2 and 3 times more likely to develop hypertension when compared to those on non-nucleoside reverse transcriptase inhibitors (NNRTIs). However, these relationships were abrogated by sex, as self-reported male sex was the major contributor in predicting incident hypertension. While none of the factors remained significantly associated with incident hypertension upon multivariate analysis among females, body mass index (BMI), and use of protease inhibitors remained strongly associated with hypertension among males.

Conclusion

Our results indicate that the use of protease inhibitors and BMI are important predictors of incident hypertension among males. Thus, blood pressure and BMI should be closely monitored, particularly in males living with HIV on protease inhibitors. In addition, identifying specific factors that protect females from developing hypertension early is important but remains to be determined.

Prevalence of Prehypertension among Saudi Adults: A Narrative Review

Background:

Prehypertension is a pre-disease state wherein an individual has a blood pressure (BP) measurement above normal (≥120/80 mmHg) but below the hypertensive range (<140/90 mmHg). Large population-based studies have shown that individuals with a BP in the prehypertensive range have an increased risk of developing hypertension and cardiovascular events. Despite these risks and high mortality rates associated with pre-hypertension, there are currently no reviews that define the prevalence of pre-hypertension in the Saudi population.

Objective:

To determine the magnitude of the pre-hypertension problem among Saudi adults and identify areas for future research based on the current gaps in the literature.

Methods:

This narrative review considers studies addressing the prevalence of pre-hypertension among Saudi adults; 8 studies were identified for this review.

Results:

In total, 14,782 men and women participated in these studies. The overall prevalence of pre-hypertension in both sexes ranged from 18.5-54.9%. Men had higher rates of pre-hypertension (24.7-66.1%) than women (7-48.1%).A modifiable risk factor reported in the majority of the studies was increased adiposity.

Conclusion:

Lifestyle changes to reduce weight may be effective in preventing or at least delaying the progression to hypertension and its associated cardiovascular events. Large, prospective, epidemiological studies are needed to estimate the risk of incident hypertension and cardiovascular events in pre-hypertension patients. Randomized clinical trials are also needed to evaluate the effectiveness of lifestyle modification and/or pharmacotherapy in reducing the risk of incident hypertension.

Salt Sensitivity of Blood Pressure and Aldosterone: Interaction Between the Lysine-specific Demethylase 1 Gene, Sex, and Age

CONTEXT

Salt sensitivity of blood pressure (SSBP) is associated with increased cardiovascular risk, especially in individuals of African descent, although the underlying mechanisms remain obscure. Lysine-specific demethylase 1 (LSD1) is a salt-sensitive epigenetic regulator associated with SSBP and aldosterone dysfunction. An LSD1 risk allele in humans is associated with SSBP and lower aldosterone levels in hypertensive individuals of African but not European descent. Heterozygous knockout LSD1 mice display SSBP and aldosterone dysregulation, but this effect is modified by age and biological sex. This might explain differences in cardiovascular risk with aging and biological sex in humans.

OBJECTIVE

This work aims to determine if LSD1 risk allele (rs587618) carriers of African descent display a sex-by-age interaction with SSBP and aldosterone regulation.

METHODS

We analyzed 297 individuals of African and European descent from the HyperPATH cohort. We performed multiple regression analyses for outcome variables related to SSBP and aldosterone.

RESULTS

LSD1 risk allele carriers of African (but not European) descent had greater SSBP than nonrisk homozygotes. Female LSD1 risk allele carriers of African descent had greater SSBP, mainly relationship-driven by women with low estrogen (postmenopausal). There was a statistically significant LSD1 genotype-sex interaction in aldosterone response to angiotensin II stimulation in individuals aged 50 years or younger, with female carriers displaying decreased aldosterone responsiveness.

CONCLUSION

SSBP associated with LSD1 risk allele status is driven by women with a depleted estrogen state. Mechanisms related to a resistance to develop SSBP in females are uncertain but may relate to an estrogen-modulating effect on mineralocorticoid receptor (MR) activation and/or LSD1 epigenetic regulation of the MR.

Understanding the dynamics of SARS-CoV-2 variants of concern in Ontario, Canada: a modeling study

A year after the initial wild-type Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) strains began their devastation of the world, they were supplanted by new variants of concern (VOC). In Ontario, Canada, the wild type was overtaken first by the Alpha/B1.1.17 variant, and then by the Delta/B.1.617 variant. The principal objective of the present study is to develop and apply a much expanded Susceptible-Infection-Recovered-type model to better understand the spread of multiple VOC, and assess the effectiveness of vaccination and non-pharmaceutical interventions (NPI). The model represents competition among VOC, and reveals their mutual inhibitory effects. By separately tracking asymptomatic and symptomatic infections, model simulations identify a significant role of vaccine breakthrough in the spread of Delta. Furthermore, the severity of a Delta outbreak depends not only on the NPI and vaccination rate but also on the vaccine types. Alarmingly, despite Ontario's existing NPI and relatively successful vaccine rollout, a future, more dangerous VOC could potentially infect a significant fraction of the province's population and overwhelm the health care system. To stop that VOC, the province may need the simultaneous and rapid deployment of a third booster vaccine and stringent NPI.

Adaptive Changes in single-nephron GFR, Tubular Morphology, and Transport in a Pregnant Rat Nephron: Modeling and Analysis

Normal pregnancy is characterized by massive increases in plasma volume and electrolyte retention. Given that the kidneys regulate homeostasis of electrolytes and volume, the organ undergoes major adaptations in morphology, hemodynamics, and transport to achieve the volume and electrolyte retention required in pregnancy. These adaptations are complex, sometimes counterintuitive, and not fully understood. In addition, the demands of the developing fetus and placenta change throughout the pregnancy. For example, during late pregnancy, K⁺ retention and thus enhanced renal K⁺ reabsorption is required despite many kaliuretic factors. The goal of this study is to unravel how known adaptive changes along the nephrons contribute to the ability of the kidney to meet volume and electrolyte requirements in mid- and late pregnancy. We developed computational models of solute and water transport in the superficial nephron of the kidney of a rat in mid- and late pregnancy. The mid-pregnant and late-pregnant rat superficial nephron models predict that morphological adaptations and increased activity of the sodium hydrogen exchanger 3 (NHE3) and epithelial sodium channel (ENaC) are essential for enhanced Na⁺ reabsorption observed during pregnancy. Model simulations showed that for sufficient K⁺ reabsorption, increased H ⁺-K ⁺-ATPase activity and decreased K⁺ secretion along the distal segments is required in both mid- and late-pregnancy. Furthermore, certain known sex differences in renal transporter pattern (e.g., the higher NHE3 protein abundance but lower activity in the proximal tubules of virgin female rats compared to male) may serve to better prepare the female for the increased transport demand in pregnancy.

The sympathies of the body: functional organization and neuronal differentiation in the peripheral sympathetic nervous system

During the last 30 years, our understanding of the development and diversification of postganglionic sympathetic neurons has dramatically increased. In parallel, the list of target structures has been critically extended from the cardiovascular system and selected glandular structures to metabolically relevant tissues such as white and brown adipose tissue, lymphoid tissues, bone, and bone marrow. A critical question now emerges for the integration of the diverse sympathetic neuron classes into neural circuits specific for these different target tissues to achieve the homeostatic regulation of the physiological ends affected.

Modeling within-Host SARS-CoV-2 Infection Dynamics and Potential Treatments

The goal of this study was to develop a mathematical model to simulate the actions of drugs that target SARS-CoV-2 virus infection. To accomplish that goal, we have developed a mathematical model that describes the control of a SARS-CoV-2 infection by the innate and adaptive immune components. Invasion of the virus triggers the innate immunity, whereby interferon renders some of the target cells resistant to infection, and infected cells are removed by effector cells. The adaptive immune response is represented by plasma cells and virus-specific antibodies. The model is parameterized and then validated against viral load measurements collected in COVID-19 patients. We apply the model to simulate three potential anti-SARS-CoV-2 therapies: (1) Remdesivir, a repurposed drug that has been shown to inhibit the transcription of SARS-CoV-2, (2) an alternative (hypothetical) therapy that inhibits the virus' entry into host cells, and (3) convalescent plasma transfusion therapy. Simulation results point to the importance of early intervention, i.e., for any of the three therapies to be effective, it must be administered sufficiently early, not more than a day or two after the onset of symptoms. The model can serve as a key component in integrative platforms for rapid in silico testing of potential COVID-19 therapies and vaccines.

His and her mathematical models of physiological systems

Beyond the reproductive system and reproductive behaviors, men and women exhibit major differences in many organ systems, including the anatomy of the brain, the activities of the stress and immune systems, and the metabolic and cardiovascular functions. A comprehensive understanding of the impact of these sex differences on health and disease is crucial to the development of effective sex-based therapies. Mathematical modeling has the potential of facilitating and contributing to advancing the understanding of sex differences in health and disease. Indeed, explosion of mathematical models have been developed in recent decades for different aspects of human physiology and pathophysiology. This review contains a survey of sex-specific mathematical models of physiological systems, describe insights that have been revealed in those modeling studies, and discuss future opportunities.

Sex differences associated with adverse drug reactions resulting in hospital admissions

Background

Adverse drug events, including adverse drug reactions (ADRs), are responsible for approximately 5% of unplanned hospital admissions: a major health concern. Women are 1.5–1.7 times more likely to develop ADRs. The main objective was to identify sex differences in the types and number of ADRs leading to hospital admission.

Methods

ADR-related hospital admissions between 2005 and 2017 were identified from the PHARMO Database Network using hospital discharge diagnoses. Patients aged ≥ 16 years with a drug possibly responsible for the ADR and dispensed within 3 months before admission were included. Age-adjusted odds ratios (OR) with 95% CIs for drug-ADR combinations for women versus men were calculated.

Results

A total of 18,469 ADR-related hospital admissions involving women (0.35% of all women admitted) and 14,678 admissions involving men (0.35% of all men admitted) were included. Most substantial differences were seen in ADRs due to anticoagulants and diuretics. Anticoagulants showed a lower risk of admission with persistent haematuria (ORadj 0.31; 95%CI 0.21, 0.45) haemoptysis (ORadj 0.47, 95%CI 0.30,0.74) and subdural haemorrhage (ORadj 0.61; 95%CI 0.42,0.88) in women than in men and a higher risk of rectal bleeding in women (ORadj 1.48; 95%CI 1.04,2.11). Also, there was a higher risk of admission in women using thiazide diuretics causing hypokalaemia (ORadj 3.03; 95%CI 1.58, 5.79) and hyponatraemia (ORadj 3.33, 95%CI 2.31, 4.81) than in men.

Conclusions

There are sex-related differences in the risk of hospital admission in specific drug-ADR combinations. The most substantial differences were due to anticoagulants and diuretics.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13293-021-00377-0.

Impact of sex and pathophysiology on optimal drug choice in hypertensive rats: quantitative insights for precision medicine

Less than half of all hypertensive patients receiving treatment are successful in normalizing their blood pressure. Despite the complexity and heterogeneity of hypertension, the current antihypertensive guidelines are not tailored to the individual patient. As a step toward individualized treatment, we develop a quantitative systems pharmacology model of blood pressure regulation in the spontaneously hypertensive rat (SHR) and generate sex-specific virtual populations of SHRs to account for the heterogeneity between the sexes and within the pathophysiology of hypertension. We then used the mechanistic model integrated with machine learning tools to study how variability in these mechanisms leads to differential responses in rodents to the four primary classes of antihypertensive drugs. We found that both the sex and the pathophysiological profile of the individual play a major role in the response to hypertensive treatments. These results provide insight into potential areas to apply precision medicine in human primary hypertension.

Sex- and Gender-Based Pharmacological Response to Drugs

In humans, the combination of all sex-specific genetic, epigenetic, and hormonal influences of biologic sex produces different in vivo environments for male and female cells. We dissect how these influences of sex modify the pharmacokinetics and pharmacodynamics of multiple drugs and provide examples for common drugs acting on specific organ systems. We also discuss how gender of physicians and patients may influence the therapeutic response to drugs. We aim to highlight sex as a genetic modifier of the pharmacological response to drugs, which should be considered as a necessary step toward precision medicine that will benefit men and women. SIGNIFICANCE STATEMENT: This study discusses the influences of biologic sex on the pharmacokinetics and pharmacodynamics of drugs and provides examples for common drugs acting on specific organ systems. This study also discusses how gender of physicians and patients influence the therapeutic response to drugs.

Sex-Specific Differences in Related Indicators of Blood Pressure in School-Age Children With Overweight and Obesity: A Cross-Sectional Study

Objective: The objective of this study is to further explore the difference between elevated blood pressure (EBP), elevated pulse pressure (EPP), and elevated mean arterial pressure (EMAP) and obesity in Chinese school-age children by sex. Methods: We performed a cross-sectional study of 935 children between 7 and 12 years old. Overweight and obesity were defined by body mass index and body composition. The multivariate logistic regression and the adjusted population attributable risk were used to assess the effects of obesity on pre-EBP/EBP, EPP, and EMAP. The interactions were used to identify the modification of obese on the relationship between related indicators of blood pressure and height or age. Results: The average age of the children included in the study was 10. Boys with overweight and obesity had higher pre-EBP/EBP, EPP, and EMAP (p < 0.05). The multivariate logistic regression analysis showed that overweight and obesity had a greater impact on BP and MAP than PP, especially in boys [odds ratio (OR) > 1]. Pre-EBP/EBP in 79% of boys and 76% of girls could be attributable to the visceral fat level. The interaction between BP, PP, MAP, and height or age was modestly increased in children with overweight and obesity, especially in boys. Conclusions: Independent of age and height, obesity not only increases blood pressure, it also increases mean arterial pressure and pulse pressure, and this effect is more pronounced in boys.

Sexual Dimorphism of Metabolomic Profile in Arterial Hypertension

Metabolomic studies have demonstrated the existence of biological signatures in blood of patients with arterial hypertension, but no study has hitherto reported the sexual dimorphism of these signatures. We compared the plasma metabolomic profiles of 28 individuals (13 women and 15 men) with essential arterial hypertension with those of a healthy control group (18 women and 18 men), using targeted metabolomics. Among the 188 metabolites explored, 152 were accurately measured. Supervised OPLS-DA (orthogonal partial least squares-discriminant analysis) showed good predictive performance for hypertension in both sexes (Q2cum = 0.59 in women and 0.60 in men) with low risk of overfitting (p-value-CV ANOVA = 0.004 in women and men). Seventy-five and 65 discriminant metabolites with a VIP (variable importance for the projection) greater than 1 were evidenced in women and men, respectively. Both sexes showed a considerable increase in phosphatidylcholines, a decrease in C16:0 with an increase in C28:1 lysophosphatidylcholines, an increase in sphingomyelins, as well as an increase of symmetric dimethylarginine (SDMA), acetyl-ornithine and hydroxyproline. Twenty-nine metabolites, involved in phospholipidic and cardiac remodeling, arginine/nitric oxide pathway and antihypertensive and insulin resistance mechanisms, discriminated the metabolic sexual dimorphism of hypertension. Our results highlight the importance of sexual dimorphism in arterial hypertension.

Sex-specific computational models for blood pressure regulation in the rat

In the past decades, substantial effort has been devoted to the development of computational models of the cardiovascular system. Some of these models simulate blood pressure regulation in humans and include components of the circulatory, renal, and neurohormonal systems. Although such human models are intended to have clinical value in that they can be used to assess the effects and reveal mechanisms of hypertensive therapeutic treatments, rodent models would be more useful in assisting the interpretation of animal experiments. Also, despite well-known sexual dimorphism in blood pressure regulation, almost all published models are gender neutral. Given these observations, the goal of this project is to develop the first computational models of blood pressure regulation for male and female rats. The resulting sex-specific models represent the interplay among cardiovascular function, renal hemodynamics, and kidney function in the rat; they also include the actions of the renal sympathetic nerve activity and the renin-angiotensin-aldosterone system as well as physiological sex differences. We explore mechanisms responsible for blood pressure and renal autoregulation and notable sexual dimorphism. Model simulations suggest that fluid and sodium handling in the kidney of female rats, which differs significantly from males, may contribute to their observed lower salt sensitivity as compared with males. Additionally, model simulations highlight sodium handling in the kidney and renal sympathetic nerve activity sensitivity as key players in the increased resistance of females to angiotensin II-induced hypertension as compared with males.

Analyse biochimique multi-paramétrique révélant une augmentation de l'homocystéinémie et du NT-ProBNP chez les patients hypertendus à Bamako (Mali)

Introduction

L'hypertension artérielle est un problème majeur de santé publique en Afrique subsaharienne par sa fréquence élevée et le risque cardiovasculaire qu'elle entraine. L'objectif de cette étude était d'évaluer la prévalence des facteurs de risques cliniques et biologiques de l'hypertension artérielle à Bamako (Mali).

Méthodes

Il s'agit d'une étude cas-témoin, stratifiée en fonction du sexe, portant sur 72 participants dont 36 hypertendus et 36 contrôles. Vingt-deux paramètres biochimiques plasmatiques ont été mesurés et analysés par des tests univariés et multivariés.

Résultats

Une hyperhomocystéinémie a été retrouvée chez 55,6% des femmes (p = 0,03) et 100% des hommes (p = 0,007) hypertendus. Le N-terminal pro B-type natriuretic peptide (NT-Pro-BNP) était également augmenté chez 16,7% des femmes (VIP > 1 dans le modèle multivarié) et des hommes hypertendus (p = 0,00006). Un bon modèle multivarié prédictif (OPLS-DA) a uniquement été obtenu chez les femmes hypertendues, avec un Q²cum = 0,73, attestant ainsi d'un important dimorphisme sexuel associé à l'hypertension artérielle. Ce modèle impliquait huit paramètres dont la concentration plasmatique était modifiée (homocystéine, NT-Pro-BNP, potassium, urée, glycémie, sodium, chlore et protéines totales).

Conclusion

Nous avons noté une association significative entre l'hyperhomocystéinémie et l'hypertension artérielle. Par conséquent, le dosage de l'homocystéine associé à une bonne prise en charge diminuerait le risque cardiovasculaire tout en améliorant la qualité de vie des patients hypertendus.

Sex differences in the metabolic effects of the renin-angiotensin system

Obesity is a global epidemic that greatly increases risk for developing cardiovascular disease and type II diabetes. Sex differences in the obese phenotype are well established in experimental animal models and clinical populations. While having higher adiposity and obesity prevalence, females are generally protected from obesity-related metabolic and cardiovascular complications. This protection is, at least in part, attributed to sex differences in metabolic effects of hormonal mediators such as the renin-angiotensin system (RAS). Previous literature has predominantly focused on the vasoconstrictor arm of the RAS and shown that, in contrast to male rodent models of obesity and diabetes, females are protected from metabolic and cardiovascular derangements produced by angiotensinogen, renin, and angiotensin II. A vasodilator arm of the RAS has more recently emerged which includes angiotensin-(1-7), angiotensin-converting enzyme 2 (ACE2), mas receptors, and alamandine. While accumulating evidence suggests that activation of components of this counter-regulatory axis produces positive effects on glucose homeostasis, lipid metabolism, and energy balance in male animal models, female comparison studies and clinical data related to metabolic outcomes are lacking. This review will summarize current knowledge of sex differences in metabolic effects of the RAS, focusing on interactions with gonadal hormones and potential clinical implications.