Sex and the renin angiotensin system: implications for gender differences in the progression of kidney disease

Thymosin alpha1 use in adult COVID-19 patients: A systematic review and meta-analysis on clinical outcomes

OBJECTIVE

Thymosin alpha1 (Ta1) is widely used to treat patients with coronavirus disease 2019 (COVID-19), however, its effect remains unclear. This systematic review and meta-analysis aimed to evaluate the effect of Ta1 as a COVID-19 therapy.

METHODS

PubMed, EMBASE, the Cochrane library, Web of Science, and the reference lists of relevant articles were searched to identify eligible studies. Assessment of heterogeneity was done using the I-squared (I²) test and random/fixed effect analysis was done to determine the risk ratio (RR). We polled the data related to mortality mainly by using Review Manager 5.4. Predefined subgroup analyses and sensitivity analyses were also performed.

RESULTS

A total of 9 studies were included, on a total of 5352 (Ta1 = 1152, control = 4200) patient outcomes. Meta-analysis results indicated that Ta1 therapy had no statistically significant effect on mortality [RR 1.03 (0.60, 1.75), p = 0.92, I² = 90 %]. Subgroup analyses demonstrated that the beneficial effect in mortality was associated with mean age＞60 years in the Tα1 group [RR 0.68 (0.58, 0.78), p < 0.0000.1, I² = 0 %], the proportion of female ≤ 40 % in the Tα1 group [RR 0.67 (0.58, 0.77), p < 0.0000.1, I² = 0 %], and severe/critical COVID-19 patients [RR 0.66 (0.57, 0.76), p < 0.0000.1, I² = 0 %]. Sensitivity analysis further demonstrated the results to be robust.

CONCLUSIONS

The results of this meta-analysis do not support the use of Ta1 in hospitalized adult COVID-19 patients.

SARS-CoV-2 Infection, Sex-Related Differences, and a Possible Personalized Treatment Approach with Valproic Acid: A Review

Sex differences identified in the COVID-19 pandemic are necessary to study. It is essential to investigate the efficacy of the drugs in clinical trials for the treatment of COVID-19, and to analyse the sex-related beneficial and adverse effects. The histone deacetylase inhibitor valproic acid (VPA) is a potential drug that could be adapted to prevent the progression and complications of SARS-CoV-2 infection. VPA has a history of research in the treatment of various viral infections. This article reviews the preclinical data, showing that the pharmacological impact of VPA may apply to COVID-19 pathogenetic mechanisms. VPA inhibits SARS-CoV-2 virus entry, suppresses the pro-inflammatory immune cell and cytokine response to infection, and reduces inflammatory tissue and organ damage by mechanisms that may appear to be sex-related. The antithrombotic, antiplatelet, anti-inflammatory, immunomodulatory, glucose- and testosterone-lowering in blood serum effects of VPA suggest that the drug could be promising for therapy of COVID-19. Sex-related differences in the efficacy of VPA treatment may be significant in developing a personalised treatment strategy for COVID-19.

Association of the angiotensin I converting enzyme (ACE) gene polymorphisms with recurrent aphthous stomatitis in the Czech population: case–control study

Background

Recurrent aphthous stomatitis (RAS) is multifactorial disease with unclear etiopathogenesis. The aim of this study was to determine distribution of the angiotensin I converting enzyme (ACE) gene polymorphisms and their influence on RAS susceptibility in Czech population.

Methods

The study included 230 subjects (143 healthy controls and 87 patients with RAS) with anamnestic, clinical and laboratory data. Five ACE gene polymorphisms (rs4291/rs4305/rs4311/rs4331/rs1799752 = ACE I/D) were determined by TaqMan technique.

Results

The allele and genotype distributions of the studied ACE I/D polymorphisms were not significantly different between subjects with/without RAS (P_corr > 0.05). However, carriers of II genotype were less frequent in the RAS group (OR = 0.48, 95% CI = 0.21–1.12, P = 0.059). Stratified analysis by sex demonstrated lower frequency of II genotype in women (OR = 0.33, 95% CI = 0.09–1.17, P < 0.035, P_corr > 0.05, respectively) than in men with RAS (P > 0.05). Moreover, the frequency of AGTGD haplotype was significantly increased in RAS patients (OR = 13.74, 95% CI = 1.70–110.79, P = 0.0012, P_corr < 0.05). In subanalysis, TGD haplotype was significantly more frequent in RAS patients (P < 0.00001) and CGI haplotype was less frequent in RAS patients (P < 0.01), especially in women (P = 0.016, P_corr > 0.05).

Conclusions

Our study indicates that while the AGTGD and TGD haplotypes are associated with increased risk of RAS development, CGI haplotype might be one of protective factors against RAS susceptibility in Czech population.

Gender differences in new hypoglycemic drug effects on renal outcomes: a systematic review

INTRODUCTION

Lifetime diabetes risk is greater in women than in men. Women with diabetes mellitus (DM) have a greater prevalence of diabetic kidney disease (DKD) risk factors. The diagnosis of DM is often delayed in women, with poorer outcomes and with expected therapeutic goals missed.

AREA COVERED

A systematic literature review following PRISMA guidelines was conducted in the PubMed gateway of the MEDLINE database and Clinicaltrials.gov. The purpose of our research was to establish the sex differences on renal outcomes in users of the new hypoglycemic drugs: sodium-glucose transport protein 2 inhibitors (SGLT-2i), dipeptidyl peptidase-IV Inhibitors (DPP-IVi) and glucagon-like peptide-1 inhibitors (GLP-1i).

EXPERT OPINION

New hypoglycemic drugs represent promising tools in the treatment and prevention of severe complications of diabetes, cardiovascular diseases and chronic kidney disease. Even if renal outcomes are investigated in both randomized controlled trials and cardiovascular outcome trials, gender-based analysis is not always performed. This may lead to relevant information for risk-benefit evaluation and therapeutic choices being missed, with gender-based equality in outcomes lacking. Our systematic review demonstrated that the gap among sexes in DKD can be partially filled using new hypoglycemic drugs. Sexual dimorphism analysis could represent a keystone for the development of adequate gender-specific therapies.

Sex and Gender Related Differences in Diabetic Kidney Disease

Diversity in sex and gender are important considerations in the pathogenesis, prognostication, research, and management of diabetic kidney disease (DKD). Sex and gender differences in the disease risk, disease-specific mechanisms, and outcomes in DKD may be attributed to biological differences between males and females at the cellular and tissue level, inconsistencies in the diagnostic and assessment tools used in chronic kidney disease and DKD, as well societal differences in the way men, women, and gender-diverse individuals self-manage and interact with health care systems. This review outlines key considerations related to the impact of sex on DKD, specifically elaborating on how they contribute to observed differences in disease epidemiology, pathogenesis, and treatment strategies. We also highlight the effect of gender on DKD progression and care.

Alterations in renin-angiotensin receptors are not responsible for exercise preconditioning of skeletal muscle fibers

Endurance exercise training promotes a protective phenotype in skeletal muscle known as exercise preconditioning. Exercise preconditioning protects muscle fibers against a variety of threats including inactivity-induced muscle atrophy. The mechanism(s) responsible for exercise preconditioning remain unknown and are explored in these experiments. Specifically, we investigated the impact of endurance exercise training on key components of the renin-angiotensin system (RAS). The RAS was targeted because activation of the classical axis of the RAS pathway via angiotensin II type I receptors (AT1Rs) promotes muscle atrophy whereas activation of the non-classical RAS axis via Mas receptors (MasRs) inhibits the atrophic signaling of the classical RAS pathway. Guided by prior studies, we hypothesized that an exercise-induced decrease in AT1Rs and/or increases in MasRs in skeletal muscle fibers is a potential mechanism responsible for exercise preconditioning. Following endurance exercise training in rats, we examined the abundance of AT1Rs and MasRs in both locomotor and respiratory muscles. Our results indicate that endurance exercise training does not alter the protein abundance of AT1Rs or MasRs in muscle fibers from the diaphragm, plantaris, and soleus muscles compared to sedentary controls (p ​> ​0.05). Furthermore, fluorescent angiotensin II (AngII) binding analyses confirm our results that exercise preconditioning does not alter the protein abundance of AT1Rs in the diaphragm, plantaris, and soleus (p ​> ​0.05). This study confirms that exercise-induced changes in RAS receptors are not a key mechanism that contributes to the beneficial effects of exercise preconditioning in skeletal muscle fibers.

Sex differences in solute and water handling in the human kidney: Modeling and functional implications

The kidneys maintain homeostasis by controlling the amount of water and electrolytes in the blood. That function is accomplished by the nephrons, which transform glomerular filtrate into urine by a transport process mediated by membrane transporters. We postulate that the distribution of renal transporters along the nephron is markedly different between men and women, as recently shown in rodents. We hypothesize that the larger abundance of a renal Na+ transport in the proximal tubules in females may also better prepare them for the fluid retention adaptations required during pregnancy and lactation. Also, kidneys play a key role in blood pressure regulation, and a popular class of anti-hypertensive medications and angiotensin converting enzymes (ACE) inhibitors have been reported to be less effective in women. Model simulations suggest that the blunted natriuretic and diuretic effects of ACE inhibition in women can be attributed, in part, to their higher distal baseline transport capacity.

SARS CoV2 infection _The longevity study perspectives

Like other infectious diseases, COVID-19 shows a clinical outcome enormously variable, ranging from asymptomatic to lethal. In Italy, like in other countries, old male individuals, with one or more comorbidity, are the most susceptible group, and show, consequently, the highest mortality, and morbidity, including lethal respiratory distress syndrome, as the most common complication. In addition, another extraordinary peculiarity, that is a surprising resistance to COVID-19, characterizes some Italian nonagenarians/centenarians. Despite having the typical COVID-19 signs and/or symptoms, such exceptional individuals show a surprising tendency to recover from illness and complications. On the other hand, long-lived people have an optimal performance of immune system related to an overexpression of anti-inflammatory variants in immune/inflammatory genes, as demonstrated by our and other groups. Consequently, we suggest long-lived people as an optimal model for detecting genetic profiles associated with the susceptibility and/or protection to COVID-19, to utilize as potential pharmacological targets for preventing or reducing viral infection in more vulnerable individuals.

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.

Protective Role of Angiotensin II Type 1 Receptor Blocker on Short Time Effect of Oleic Acid Induced Lung and Kidney Injury

Backgrounds:

Acute respiratory distress syndrome (ARDS) causes high mortality rate in clinic, and the pathogenesis of this syndrome may interact with renin angiotensin system (RAS) components. The main objective of this study was to determine the protective role of AT1R antagonist (losartan) on oleic acid (OA) induced ARDS and kidney injury.

Methods:

The animal model of ARDS was performed by intravenous administration of 250 μl/kg oleic acid (OA). Male and female rats were subjected to received intravenously vehicle (saline, groups 1 and 4), OA (groups 2 and 5), or losartan (10 mg/kg) plus OA (groups 3 and 6), and six hour later, the measurements were performed.

Results:

Co-treatment of OA and losartan increased the serum levels of blood urea nitrogen significantly (P < 0.05) and creatinine insignificantly in both gender. However, the OA induced kidney damage was decreased by losartan significantly in male (P < 0.05) and insignificantly in female rats. In addition, co-treatment of OA and losartan decreased lung water content significantly in male rats (P < 0.05). Based on tissue staining, no significant difference in lung tissue damages were observed between the groups, however some exudate were observed in lung male rats treated with OA alone which were abolished by losartan.

Conclusions:

Losartan may protect the kidney and lung against OA induced tissue injury in male rats. This protective action is not certain in female rats.

Association of Predicted Lean Body Mass and Fat Mass With Incident Diabetic Nephropathy in Participants With Type 2 Diabetes Mellitus: A Post Hoc Analysis of ACCORD Trial

BACKGROUND

Lean body mass (LBM) and fat mass (FM) have been shown to have different associations with several chronic diseases but little is known about the sex-specific association of LBM and FM with diabetic nephropathy (DN) risk among participants with diabetes.

METHODS

Participants from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) study was used in a post hoc analysis to examine the association of predicted LBM index (LBMI) and FM index (FMI) with incident DN risk (defined as a composite outcome of three types of predefined DN). Because of sex differences in body composition, analyses were conducted separately using sex-specific quartiles of predicted LBMI and FMI.

RESULTS

Of the 9,022 participants with type 2 diabetes (5,575 men and 3,447 women) included in this study, 5,374 individuals developed DN (3,396 in men and 1,978 in women). Higher quartiles of LBMI were associated with a reduced risk of DN while higher quartiles of FMI were associated with an increased higher risk of DN among men but not women. Compared with the lowest quartile, the fully adjusted hazard ratios (HRs) and 95% confidence intervals (CIs)for the highest quartile of predicted LBMI and FMI were respectively 0.83 (95% CI 1.71 - 0.96) and 1.23 (95% CI 1.06-1.43) among men; and 0.92 (95% CI 0.63 - 1.33) and 1.14 (95% CI 0.79 - 1.63) among women.

CONCLUSIONS

Among participants with diabetes, predicted LBMI was inversely associated with risk of DN while predicted FMI was positively associated with an increased risk of incident DN among men but not women. Trial registration: ClinicalTrials.gov., no. NCT00000620.

Involvement of sex hormones, oxidative stress, ACE and ACE2 activity in the impairment of renal function and remodelling in SHR

AIMS

Hypertension is a relevant sex and sex hormones-dependent risk factor where the cardiovascular and renal health of the population are concerned. Men experience greater losses of renal function (RF) than women, but the mechanisms remain somewhat unclear. Our goal was to evaluate the relationship between oxidative stress (OS), angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2) activities and RF in male and female SHR.

MAIN METHODS

Twelve-week-old spontaneously hypertensive rats (SHR) were submitted to either castration or SHAM surgery and divided into 4 groups, SHAM or Castrated (CAST) males or females. After 51 days we evaluated RF (inulin and sodium para-aminohippurate), ACE and ACE2 activities (fluorimetry), OS (flow cytometry), collagen deposition (picrosirius red) and protein expression (western blot).

KEY FINDINGS

Males presented lower RF than females and castration impaired this parameter in both groups. Sexual dimorphism was not observed regarding OS and inflammation; however, castration increased this parameter more severely in males than in females. SHAM males exhibited higher collagen deposition than females, though castration increased it in both sexes, eliminating the difference. We found sexual dimorphism regarding renal ACE and ACE2 activities, which were lower in males than in females. Although castration did not alter ACE activity, it reduced ACE2 activity in females and increased it in males.

SIGNIFICANCE

These results indicate that sex hormones affect RF in SHR. As alterations in the oxidative system were capable of promoting podocyte injury, inflammation, and collagen deposition, we put forward that these effects are differently modulated by ACE and ACE2.

The renin angiotensin aldosterone system and COVID-19

The ongoing pandemic has stimulated study of the Renin Angiotensin Aldosterone System (RAAS), and how it can be manipulated to treat COVID-19. Studies are examining whether drugs that act on the RAAS system might be useful to treat COVID-19. COVID-19 and the RAAS are closely linked both in infection and in possible post-infection inflammatory cascades. We detail the Physiology and Pharmacology of the RAAS including the effects of aldosterone and atrial natriuretic peptide. It is appropriate that the theoretical benefits of modulation of the RAAS should be considered based on available knowledge of the complexity of the system. In this short review we have tried to explain the actions of the angiotensin family of peptides and produce a relatively simple model and diagrammatic summary of the RAAS and the possible sites of intervention.

Systematic Review and Meta-Analysis of Sex-Specific COVID-19 Clinical Outcomes

To successfully mitigate the extraordinary devastation caused by the Coronavirus disease 2019 (COVID-19) pandemic, it is crucial to identify important risk factors for this disease. One such neglected health determinant is the sex of the patient. This is an essential clinical characteristic, as it can factor into a patient's clinical management and preventative measures. Some clinical studies have shown disparities in the proportion between males and females that have more severe clinical outcomes or, subsequently, die from this disease. However, this association has not been unequivocally established. Thus, the purpose of this investigation was to examine the association between male sex and COVID-19 severity. We systematically reviewed the literature, identified studies that matched predetermined selection criteria, and performed a meta-analysis to evaluate the proportion of males among four disease severity categories. Appropriate assessment strategies were implemented to assess and minimize potential biases. The results of this meta-analysis indicated that males constituted a significantly higher proportion of those who had adverse clinical outcomes and died from COVID-19. As the coronavirus spread from the East to the West, male sex remained a consistent risk factor. Our results support the establishment of the male sex as an important risk factor for this disease. Early identification and appropriate medical care for males with lab-confirmed COVID-19 may substantially change the course of clinical prognosis, resulting in greater numbers of lives saved.

Effects of Estrogen in Gender-dependent Fetal Programming of Adult Cardiovascular Dysfunction

BACKGROUND

Epidemiological studies and experimental studies have demonstrated that intrauterine adverse environment increases the risk of Cardiovascular Disease (CVD) in adulthood. However, whether an individual develops a cardiovascular dysfunctional phenotype may depend on genetic background, age, and sex.

METHODS

In this review, we summarize some of the recent experimental animal studies in the developmental programming of adult CVD with an emphasis on sex differences and the potential role of estrogen in mediating sexual dimorphism.

RESULTS

Few epidemiological studies report the effect of sex on the developmental programming of CVD. However, numerous experimental animal studies have shown a sex difference in fetal programming of adult cardiovascular dysfunction. Most of the animal studies indicate that male offspring develop cardiovascular dysfunction and CVD in adulthood, whereas adult females appear to be protected. Estrogen is one of the key factors that contributes to the sex difference of adult CVD. Estrogen/its Receptor (ER) may interact with the RAS system by changes of DNA methylation patterns at the target gene promoter, serve as an antioxidant to counteract the prenatal insults-induced heightened ROS, and function as an eNOS activator to increase vasodilation, resulting in the protection of female offspring from the development of hypertension and other CVDs.

CONCLUSION

These studies suggest that estrogen/ER may contribute to sex differences in cardiovascular response to an adverse intrauterine environment and play a significant role in modulating the cardiovascular response in adulthood.

ACE2 activation protects against cognitive decline and reduces amyloid pathology in the Tg2576 mouse model of Alzheimer's disease

Mid-life hypertension and cerebrovascular dysfunction are associated with increased risk of later life dementia, including Alzheimer’s disease (AD). The classical renin–angiotensin system (cRAS), a physiological regulator of blood pressure, functions independently within the brain and is overactive in AD. cRAS-targeting anti-hypertensive drugs are associated with reduced incidence of AD, delayed onset of cognitive decline, and reduced levels of Aβ and tau in both animal models and human pathological studies. cRAS activity is moderated by a downstream regulatory RAS pathway (rRAS), which is underactive in AD and is strongly associated with pathological hallmarks in human AD, and cognitive decline in animal models of CNS disease. We now show that enhancement of brain ACE2 activity, a major effector of rRAS, by intraperitoneal administration of diminazene aceturate (DIZE), an established activator of ACE2, lowered hippocampal Aβ and restored cognition in mid-aged (13–14-month-old) symptomatic Tg2576 mice. We confirmed that the protective effects of DIZE were directly mediated through ACE2 and were associated with reduced hippocampal soluble Aβ₄₂ and IL1-β levels. DIZE restored hippocampal MasR levels in conjunction with increased NMDA NR2B and downstream ERK signalling expression in hippocampal synaptosomes from Tg2576 mice. Chronic (10 weeks) administration of DIZE to pre-symptomatic 9–10-month-old Tg2576 mice, and acute (10 days) treatment in cognitively impaired 12–13-month-old mice, prevented the development of cognitive impairment. Together these data demonstrate that ACE2 enhancement protects against and reverses amyloid-related hippocampal pathology and cognitive impairment in a preclinical model of AD.

Sex and the kidneys: current understanding and research opportunities

Concerns regarding sex differences are increasingly pertinent in scientific and societal arenas. Although biological sex and socio-cultural gender are increasingly recognized as important modulators of renal function under physiological and pathophysiological conditions, gaps remain in our understanding of the mechanisms underlying sex differences in renal pathophysiology, disease development, progression and management. In this Perspectives article, we discuss specific opportunities for future research aimed at addressing these knowledge gaps. Such opportunities include the development of standardized core data elements and outcomes related to sex for use in clinical studies to establish a connection between sex hormones and renal disease development or progression, development of a knowledge portal to promote fundamental understanding of physiological differences between male and female kidneys in animal models and in humans, and the creation of new or the development of existing resources and datasets to make them more readily available for interrogation of sex differences. These ideas are intended to stimulate thought and interest among the renal research community as they consider sex as a biological variable in future research projects.

Functional implications of the sex differences in transporter abundance along the rat nephron: modeling and analysis

The goal of the present study was to investigate the functional implications of sexual dimorphism in the pattern of transporters along the rodent nephron as reported by Veiras et al. (J Am Soc Nephrol 28: 3504-3517, 2017). To do so, we developed sex-specific computational models of water and solute transport along the superficial nephrons from male and female rat kidneys. The models account for the sex differences in the abundance of apical and basolateral transporters, single nephron glomerular filtration rate, and tubular dimensions. Model simulations predict that ~70% and 60% of filtered Na⁺ is reabsorbed by the proximal tubule of male and female rat kidneys, respectively. The lower fractional Na⁺ reabsorption in female kidneys is due primarily to their smaller transport area, lower Na⁺/H⁺ exchanger activity, and lower claudin-2 abundance, culminating in significantly larger fractional delivery of water and Na⁺ to the downstream nephron segments in female kidneys. Conversely, the female distal nephron exhibits a higher abundance of key Na⁺ transporters, including Na⁺-K⁺-Cl^- cotransporters, Na⁺-Cl^- cotransporters, and epithelial Na⁺ channels. The higher abundance of transporters accounts for the enhanced water and Na⁺ transport along the female, relative to male, distal nephron, resulting in similar urine excretion between the sexes. Consequently, in response to a saline load, the Na⁺ load delivered distally is greater in female rats than male rats, overwhelming transport capacity and resulting in higher natriuresis in female rats.

Protective Role of Angiotensin Type 1 Receptor Blockade in 4/6 Nephrectomized Male and Female Rats

Background

Chronic kidney disease associated with serious morbidity and mortality rate while it is affected by renin-angiotensin system. The effects of losartan as angiotensin II Type 1 receptor antagonist on renal functional in 4/6 nephrectomized rats was evaluated.

Methods

Twenty-six male and female Wistar rats underwent 4/6 nephrectomy, and the animals from each gender were randomly divided into two groups which treated with vehicle and losartan (10 mg/kg/day for 1 week). The parameters related to kidney function were measured.

Results

Creatinine (Cr) clearance and urine flow were improved in losartan-treated group significantly (P < 0.05). The serum level of blood urea nitrogen and Cr and kidney tissue damage score and sodium urinary output (U_NaV) did not alter. However, losartan decreased percentage of sodium excretion (E_Na%) in both genders insignificantly.

Conclusions

Losartan may improve renal function in 4/6 nephrectomized male rats.

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.

Sex Differences in Hypertension: Where We Have Been and Where We Are Going

While it has been known since the 1940s that men have greater increases in blood pressure (BP) compared with women, there have been intense efforts more recently to increase awareness that women are also at risk for developing hypertension and that cardiovascular diseases (CVDs) are the leading causes of death among both men and women in the United States. With the release of the 2017 Hypertension Clinical Guidelines, 46% of adults in the United States are now classified as hypertensive, and hypertension is the primary modifiable risk factor for the development of CVD. This increase in the prevalence of hypertension is reflected in an increase in prevalence among both men and women across all demographics, although there were greater increases in the prevalence of hypertension among men compared with women. As a result, the well-established gender difference in the prevalence of hypertension is even more pronounced and now extends into the sixth decade of life. The goals of this review are to (i) review the historical clinical trial data and hypertension guidelines from the perspective of both genders and then (ii) review the role of the renin-angiotensin system and T-cell activation in contributing to sex differences in BP control.

Sex Differences in the Behavioral Desensitization of Water Intake Observed After Repeated Central Injections of Angiotensin II

Previous in vivo and in vitro studies demonstrate that the angiotensin type 1 receptor rapidly desensitizes after exposure to angiotensin II (AngII). Behaviorally, this likely underlies the reduced drinking observed after acute repeated central injections of AngII. To date, this phenomenon has been studied exclusively in male subjects. Because there are sex differences in the dipsogenic potency of AngII, we hypothesized that sex differences also exist in desensitization caused by AngII. As expected, when male rats were pretreated with AngII, they drank less water after a test injection of AngII than did rats pretreated with vehicle. Intact cycling female rats, however, drank similar amounts of water after AngII regardless of the pretreatment. To probe the mechanism underlying this sex difference, we tested the role of gonadal hormones in adult and developing rats. Gonadectomy in adults did not produce a male-like propensity for desensitization of water intake in female rats, nor did it produce a female-like response in male rats. To test if neonatal brain masculinization generated a male-like responsiveness, female pups were treated at birth with vehicle, testosterone propionate (TP), or dihydrotestosterone (DHT). When tested as adults, TP-treated female rats showed a male-like desensitization after repeated AngII that was not found in vehicle- or DHT-treated rats. Together, these data reveal a striking sex difference in the behavioral response to elevated AngII that is mediated by organizational effects of gonadal hormones and provide an example of one of the many ways that sex influences the renin-angiotensin-aldosterone system.

The Association between Sex and Long-Term Pediatric Cardiovascular Morbidity

OBJECTIVE

To evaluate the association between sex and long-term pediatric cardiovascular morbidity.

STUDY DESIGN

A population-based cohort study was performed that compared the risk of long-term cardiovascular morbidity (up to the age of 18 years) of children according to sex. Deliveries occurred between the years 1991 and 2013 in a tertiary medical center. Multiple pregnancies and fetal congenital malformations were excluded. Kaplan-Meier survival curves were constructed to compare cumulative cardiovascular morbidity incidence. A Cox proportional hazards model was used to control for confounders, including gestational age at birth, birth weight, and maternal factors.

RESULTS

During the study period, 240 953 newborns met the inclusion criteria and were included in the long-term analysis. Of them, 51.0% (n = 122 840) were male and 49.0% (n = 118 113) female. Cardiovascular morbidity up to the age of 18 years was significantly more common in male as compared with female newborns (0.3% vs 0.2%, OR 1.33, 95% CI 1.12-1.57, P = .001). In the Cox regression model, male sex exhibited an independent association with long-term cardiovascular morbidity with an adjusted hazard ratio of 1.37 (95% CI 1.16-1.63, P <.001).

CONCLUSION

Male newborns are at an increased risk for pediatric cardiovascular morbidity independent of gestational age at birth and birth weight.

Association between Urine Albumin-to-Creatinine Ratio within the Normal Range and Incident Hypertension in Men and Women

PURPOSE

There have been few studies on gender difference in the impact of a urine albumin-to-creatinine ratio (UACR) within the normal range on the risk of hypertension. We evaluated whether the association between the UACR below the microalbuminuria range and the incident risk of hypertension is different between men and women.

MATERIALS AND METHODS

A total of 1173 individuals (442 men and 731 women) aged 40 to 70 years without hypertension was examined at baseline (2005-2008) and followed (2008-2011). We defined the UACR as the amount of albumin (mg/dL) divided by creatinine (g/dL) in randomly voided urine. The subjects were classified according to UACR tertile.

RESULTS

During an average of 2.6 years of follow-up, 57 men (12.9%) and 66 women (9.0%) developed hypertension. In multivariable-adjusted models, the odds ratio for new-onset hypertension comparing the highest and lowest tertiles of UACR was 1.83 [95% confidence interval (CI) 0.85-3.94] in men and 2.69 (95% CI 1.27-5.73) in women. In stratified analyses by menopausal status, higher tertiles of UACR were associated with an increased risk of incident hypertension in postmenopausal women.

CONCLUSION

Higher normal UACR levels were associated with an increased risk of incident hypertension in women. The UACR could have a clinical role in predicting the development of hypertension.

Menopause and Parkinson's disease. Interaction between estrogens and brain renin-angiotensin system in dopaminergic degeneration

The neuroprotective effects of menopausal hormonal therapy in Parkinson's disease (PD) have not yet been clarified, and it is controversial whether there is a critical period for neuroprotection. Studies in animal models and clinical and epidemiological studies indicate that estrogens induce dopaminergic neuroprotection. Recent studies suggest that inhibition of the brain renin-angiotensin system (RAS) mediates the effects of estrogens in PD models. In the substantia nigra, ovariectomy induces a decrease in levels of estrogen receptor-α (ER-α) and increases angiotensin activity, NADPH-oxidase activity and expression of neuroinflammatory markers, which are regulated by estrogen replacement therapy. There is a critical period for the neuroprotective effect of estrogen replacement therapy, and local ER-α and RAS play a major role. Astrocytes play a major role in ER-α-induced regulation of local RAS, but neurons and microglia are also involved. Interestingly, treatment with angiotensin receptor antagonists after the critical period induced neuroprotection.

Effects of aging on the function of the urinary system: longitudinal changes with age in selected urine parameters in a hospitalized population of older adults

Although normal aging does not have a pernicious effect on the homeostasis of fluids, renal reserve in elderly people can be depleted. The purpose of the present study was to assess the relationship between longitudinal changes with age in basic urine parameters (specific gravity and pH) in older men and women, depending on their body height and relative body weight. Longitudinal data on these two quantitative traits of the urine were available for 142 physically healthy individuals, including 68 men and 74 women. All subjects were 45 years of age at the beginning and 70 at the end of the period under investigation. All measurements were taken in accordance with internationally accepted requirements. Specific gravity was assessed using a hydrometer, and pH was measured using a pH meter. ANOVA, t-test, and regression analysis were performed. No significant sex differences in specific gravity or urine pH were observed. In both sexes, urine specific gravity decreased with age according to exponential model of regression. In men, there was a gradual increase in the pH of the urine until age 65, and the best fitting regression model was polynomial. In women, on the other hand, there was an exiguous decrease in urine pH throughout the period under study, and the best fitting regression model proved to be exponential. As the process of renal aging commences relatively early in ontogeny and manifests itself in many structural and functional changes, urinalysis and other more sophisticated methods of diagnosis of renal diseases are essential for proper assessment of health status of adults and older individuals. The rate of age-related changes in the analyzed traits of the urine was commensurate in both sexes, thereby revealing no evidence of significant sex differences in terms of renal aging in the period between 45 and 70 years of age.

Adjusting the 17β-Estradiol-to-Androgen Ratio Ameliorates Diabetic Nephropathy

Diabetes is manifested predominantly in males in experimental models, and compelling evidence suggests that 17β-estradiol (E2) supplementation improves hyperglycemia in humans. We previously generated a severely diabetic transgenic (Tg) mouse model by β-cell–specific overexpression of inducible cAMP early repressor (ICER) and found that male but not female ICER-Tg mice exhibit sustained hyperglycemia and develop major clinical and pathologic features of human diabetic nephropathy (DN). Thus, we hypothesized that differences in circulating hormone levels have a key role in determining susceptibility to diabetes. Here, we examined whether DN in male ICER-Tg mice is rescued by adjusting the androgen-to-E2 ratio to approximate that in normoglycemic female ICER-Tg mice. We treated hyperglycemic male ICER-Tg mice with orchiectomy (ORX), E2 pellet implantation, or both. E2 pellet implantation at an early stage of DN with or without ORX caused a rapid drop in blood glucose and a dramatic increase in β-cell number, and it markedly inhibited DN progression [namely, E2 reduced glomerulosclerosis, collagen 4 deposition and albuminuria, and prevented hyperfiltration]. Furthermore, E2 pellet implantation was more effective than ORX alone and induced a remarkable improvement, even when initiated at advanced-stage DN. In contrast, induction of normoglycemia by islet transplant in ICER-Tg mice eliminated albuminuria but was less effective than E2 + ORX in reducing glomerulosclerosis, collagen 4 deposition, and hyperfiltration. These findings indicate that E2 treatment is effective, even after establishment of DN, whereas glucose normalization alone does not improve sclerotic lesions. We propose that E2 intervention is a potential therapeutic option for DN.

Hemodynamic responses to acute angiotensin II infusion are exacerbated in male versus female spontaneously hypertensive rats

We previously reported that male spontaneously hypertensive rats (SHRs) are more sensitive to chronic angiotensin (Ang) II‐induced hypertension compared with female rats. This study was designed to test the hypothesis that anesthetized male SHRs are also more responsive to acute Ang II‐induced increases in blood pressure and renal hemodynamic changes when compared with female SHRs. Baseline mean arterial pressure (MAP) was higher in male SHRs than in female SHRs (135 ± 2 vs. 124 ± 4 mmHg, P < 0.05). Acute intravenous infusion of Ang II (5 ng/kg/min) for 60 minutes significantly increased MAP to 148 ± 2 mmHg in male SHRs (P < 0.05) without a significant change in MAP in female SHRs. Baseline glomerular filtration rate (GFR) was also higher in male SHRs than in female SHRs (2.6 ± 0.3 vs. 1.3 ± 0.1 mL/min, P < 0.05). Ang II infusion for 60 min significantly decreased GFR in male SHRs (2.0 ± 0.2 mL/min; P < 0.05) without significant changes in urine flow rate, sodium, or chloride excretion. In contrast, Ang II infusion increased GFR in female SHRs (1.9 ± 0.2 mL/min; P < 0.05). The increase in GFR upon Ang II infusion in female SHRs was associated with increases in urine flow rate (4.3 ± 0.3 to 7.1 ± 0.9 μL/min), sodium excretion (0.16 ± 0.04 to 0.4 ± 0.1 μmol/min), and chloride excretion (0.7 ± 0.08 to 1.1 ± 0.1 μmol/min; for all P < 0.05). These findings support the hypothesis that there is sex difference in response to acute Ang II infusion in SHRs with females being less responsive to Ang II‐induced elevations in blood pressure and decreases in GFR relative to male SHRs.

Social Determinants of Racial Disparities in CKD

Significant disparities in CKD rates and outcomes exist between black and white Americans. Health disparities are defined as health differences that adversely affect disadvantaged populations, on the basis of one or more health outcomes. CKD is the complex result of genetic and environmental factors, reflecting the balance of nature and nurture. Social determinants of health have an important role as environmental components, especially for black populations, who are disproportionately disadvantaged. Understanding the social determinants of health and appreciating the underlying differences associated with meaningful clinical outcomes may help nephrologists treat all their patients with CKD in an optimal manner. Altering the social determinants of health, although difficult, may embody important policy and research efforts, with the ultimate goal of improving outcomes for patients with kidney diseases, and minimizing the disparities between groups.

Sex Differences in Renal Proximal Tubular Cell Homeostasis

Studies in human patients and animals have revealed sex-specific differences in susceptibility to renal diseases. Because actions of female sex hormones on normal renal tissue might protect against damage, we searched for potential influences of the female hormone cycle on basic renal functions by studying excretion of urinary marker proteins in healthy human probands. We collected second morning spot urine samples of unmedicated naturally ovulating women, postmenopausal women, and men daily and determined urinary excretion of the renal tubular enzymes fructose-1,6-bisphosphatase and glutathione-S-transferase-α Additionally, we quantified urinary excretion of blood plasma proteins α1-microglobulin, albumin, and IgG. Naturally cycling women showed prominent peaks in the temporal pattern of urinary fructose-1,6-bisphosphatase and glutathione-S-transferase-α release exclusively within 7 days after ovulation or onset of menses. In contrast, postmenopausal women and men showed consistently low levels of urinary fructose-1,6-bisphosphatase excretion over comparable periods. We did not detect changes in urinary α1-microglobulin, albumin, or IgG excretion. Results of this study indicate that proximal tubular tissue architecture, representing a nonreproductive organ-derived epithelium, undergoes periodical adaptations phased by the female reproductive hormone cycle. The temporally delimited higher rate of enzymuria in ovulating women might be a sign of recurring increases of tubular cell turnover that potentially provide enhanced repair capacity and thus, higher resistance to renal damage.

Sex differences in the association between obesity and albuminuria among Korean adults: a cross-sectional study using the Korea National Health and Nutrition Examination Survey data

Background

The association between obesity and albuminuria in the general population remains unclear. We aimed to identify the association between obesity and albuminuria as well as sex differences regarding the associations using several obesity indices, including waist circumference (WC), body mass index (BMI), and waist-to-height ratio (WHR).

Methods

This study included 3841 subjects (1730 males and 2111 females; age 20–80 years) who participated in the Fifth Korea National Health and Nutrition Examination Survey conducted in 2011. Subjects with hypertension, diabetes, renal failure, or a malignant tumor and those who were pregnant or menstruating were excluded. Albuminuria was defined as a urinary albumin-to-creatinine ratio ≥30 mg/g. Anthropometric parameters were categorized into sex-specific quartiles. Logistic regression models were used to assess the associations between each anthropometric parameter and albuminuria.

Results

All of the obesity indices of the fourth quartile group of females showed a twofold higher risk for albuminuria than the second quartile group, and it was persistently significant after adjusting for age, smoking, and physical activity. After further adjustment for high blood pressure and impaired fasting glucose and triglyceride levels, WC and BMI of the fourth quartile group of females still showed a significantly higher risk for albuminuria than the second quartile group (odds ratios 1.96 and 2.24; 95 % confidence intervals 1.03–3.74 and 1.15–4.37). None of the associations between albuminuria and the obesity indices were significant in males.

Conclusion

Higher WC and BMI were significantly associated with the risk of albuminuria among females, but not males.

Electronic supplementary material

The online version of this article (doi:10.1007/s10157-016-1238-z) contains supplementary material, which is available to authorized users.

Nonpreventive Role of Aerobic Exercise Against Cisplatin-induced Nephrotoxicity in Female Rats

Background:

Cisplatin (CP) is a chemotherapy drug and nephrotoxicity is a major concern for CP therapy. CP-induced nephrotoxicity is gender-dependent, and the effect of aerobic exercise in females has not been reported yet while it has a beneficial effect in males. Hence, this study was designed to determine the protective role of aerobic exercise against CP-induced nephrotoxicity in female rats.

Methods:

Twenty-eight adult female rats were divided into four groups. Groups I and II had aerobic exercise on a treadmill for 8 weeks. Then, the exercise protocol was continued for another week in group I and stopped in group II. All animals in these groups received CP (2.5 mg/kg/day; i.p.) for 1-week. Groups III and IV were treated with CP and vehicle, respectively, without exercise. Finally, the animals were sacrificed for biochemical measurements and tissue histopathology investigations.

Results:

CP alone without exercise increased serum levels of blood urea nitrogen (BUN) and creatinine (Cr), kidney weight, and kidney tissue damage score (KTDS); while exercise could not attenuate these parameters in female rats. Exercise in females increased the serum levels of BUN and Cr and KTDS and weight loss (P < 0.05). Kidney nitrite levels reduce significantly in group I in compared to positive and negative control groups. Exercise also did not have beneficial effects on malondialdehyde levels in plasma and kidney.

Conclusions:

Aerobic exercise cannot reduce CP-induced nephrotoxicity in female rats. Increasing the damage in female rats may be related to female sex hormone estrogen or gender differences in renal hemodynamic and renin-angiotensin system activity in the presence of exercise. In general, it is recommended that the females under CP chemotherapy avoid exercising during treatment.

Sex differences in the developmental origins of cardiovascular disease

The Developmental Origins of Health and Disease (DOHaD) proposes that adverse events during early life program an increased risk for cardiovascular disease. Experimental models provide proof of concept but also indicate that insults during early life program sex differences in adult blood pressure and cardiovascular risk. This review will highlight the potential mechanisms that contribute to the etiology of sex differences in the developmental programming of cardiovascular disease.

Female spontaneously hypertensive rats have a compensatory increase in renal regulatory T cells in response to elevations in blood pressure

Female spontaneously hypertensive rats (SHR) have more regulatory T cells (Tregs) in their kidneys than males. The goal of this study was to determine the impact of blood pressure (BP) on the renal immune profile. We hypothesize that increases in BP promote a proinflammatory renal T cell and cytokine profile in SHR, although females will have greater hormone-dependent increases in Tregs and males will have greater increases in Th17 cells. Renal T cell and cytokine profiles were assessed in male and female Wistar-Kyoto rats and male and female SHR treated with vehicle or hydrochlorothiazide and reserpine (HCTZ) from 6 to 12 (6-HCTZ) or 11 to 13 weeks of age (2-HCTZ). Regardless of sex, SHR had a more proinflammatory renal immune profile than Wistar-Kyoto rats. 6-HCTZ attenuated age-related increases in BP and 2-HCTZ reversed hypertension compared with vehicle-treated SHR. Neither 6-HCTZ nor 2-HCTZ altered CD3(+), CD4(+), or CD8(+) T cells in either sex. Both treatments decreased Tregs only in female SHR abolishing sex differences in Tregs. 6-HCTZ has no impact on Th17 cells in either sex and 2-HCTZ had a minimal impact on renal Th17 cells. To further assess mechanisms mediating sex differences in the renal immune profile, male and female SHR were gonadectomized to determine the impact of sex hormones. Gonadectomy increased proinflammatory markers in both sexes, suggesting that both male and female sex hormones are anti-inflammatory. In conclusion, BP contributes to sex differences in the renal T-cell profile of SHR; female SHR increase renal Tregs in response to increases in BP.

The "his and hers" of the renin-angiotensin system

Sex differences exist in the regulation of arterial pressure and renal function by the renin-angiotensin system (RAS). This may in part stem from a differential balance in the pressor and depressor arms of the RAS. In males, the ACE/AngII/AT(1)R pathways are enhanced, whereas, in females, the balance is shifted towards the ACE2/Ang(1-7)/MasR and AT(2)R pathways. Evidence clearly demonstrates that premenopausal women, as compared to aged-matched men, are protected from renal and cardiovascular disease, and this differential balance of the RAS between the sexes likely contributes. With aging, this cardiovascular protection in women is lost and this may be related to loss of estrogen postmenopause but the possible contribution of other sex hormones needs to be further examined. Restoration of these RAS depressor pathways in older women, or up-regulation of these in males, represents a therapeutic target that is worth pursuing.

Female spontaneously hypertensive rats have greater renal anti-inflammatory T lymphocyte infiltration than males

T cells contribute to hypertension in male experimental models; data in females is lacking even though women are more likely to develop immune disorders. The goal of this study was to determine whether immune cells contribute to hypertension in female spontaneously hypertensive rats (SHR) and define the T cell profile in whole blood and kidneys of male and female SHR. We hypothesized that inflammatory cells contribute to hypertension in female SHR; however, male SHR have a higher blood pressure so we hypothesize they will have a heightened inflammatory profile. The lymphocyte inhibitor mycophenolate mofetil (MMF) was administered in a dose-dependent manner to SHR. At the highest dose (50 mg·kg(-1)·day(-1)), blood pressure was significantly decreased in both sexes, yet the percent decrease in blood pressure was greater in females (female: 12 ± 1%; males: 7 ± 1%, P = 0.01). Circulating and renal T cell profiles were defined using analytical flow cytometry. Female SHR had more circulating CD3(+), CD4(+), and pro-inflammatory CD3(+)CD4(+)RORγ(+) Th17 cells, whereas males had more immune-suppressive CD3(+)CD4(+)Foxp3(+) T regulatory cells. In the kidney, females had greater numbers of CD8(+) and T regulatory cells than males, whereas males had greater CD4(+) and Th17 cell infiltration. MMF decreased circulating and renal T cells in both sexes (P < 0.0001), although the effect of MMF on T cell subtypes was sex specific with females having greater sensitivity to MMF-induced decreases in lymphocytes. In conclusion, there is a lymphocyte contribution to the maintenance of hypertension in the female SHR and sex of the animal impacts the T cell profile.

Melatonin prevents oxidative stress in ovariectomized rats treated with aluminium

This study is designed to determine the simultaneous effect of aluminium (Al) and melatonin (Mel) treatment in intact and ovariectomized (Ovx) female rats on oxidative stress and their inter-organ relationship in the kidney and liver. Al-treated rats received an intra-peritoneal injection of solution of aluminium lactate (0.575 mg Al/100 g of body weight, three times a week), during 12 weeks. Mel groups received intra-peritoneal injections of melatonin at a dose of 10 mg/kg/day, 5 days/week, during 12 weeks. The results of this study showed that Al treatment in female rats modifies homeostasis of glutathione and the antioxidant capacity of the rat liver and kidney. The alteration of glutathione homeostasis and oxidative status was not associated with an increased lipid peroxidation in both organs with the exception of the increase observed in the liver of Ovx rats. Al also induced modifications in the activity of some enzymes related to the glutathione cycle: GSH-Px in the liver and kidney and glutathione reductase only in the kidney. Al exposure decreased CAT activity in both the kidney and liver of intact and Ovx groups. The administration of Mel in the intact and castrated females treated with Al seems to reduce oxidative changes in the liver and kidney of intact and Ovx rats.

Sex differences in the pressor and tubuloglomerular feedback response to angiotensin II

Awareness of sex differences in the pathology of cardiovascular disease is increasing. Previously, we have shown a role for the angiotensin type 2 receptor (AT(2)R) in the sex differences in the arterial pressure response to Ang II. Tubuloglomerular feedback (TGF) contributes in setting pressure-natriuresis properties, and its responsiveness is closely coupled to renal Ang II levels. We hypothesize that, in females, the attenuated pressor response to Ang II is mediated via an enhanced AT(2)R mechanism that, in part, offsets Ang II-induced sensitization of the TGF mechanism. Mean arterial pressure was measured via telemetry in male and female wild-type (WT) and AT(2)R knockout (AT(2)R-KO) mice receiving Ang II (600 ng/kg per minute SC). Basal 24-hour mean arterial pressure did not differ among the 4 groups. After 10 days of Ang II infusion, mean arterial pressure increased in the male WT (28±6 mm Hg), male AT(2)R-KO (26±2 mm Hg), and female AT(2)R-KO (26±4 mm Hg) mice, however, the response was attenuated in female WT mice (12±4 mm Hg; P between sex and genotype=0.016). TGF characteristics were determined before and during acute subpressor Ang II infusion (100 ng/kg per minute IV). Basal TGF responses did not differ between groups. The expected increase in maximal change in stop-flow pressure and enhancement of TGF sensitivity in response to Ang II was observed in the male WT, male AT(2)R-KO, and female AT(2)R-KO but not in the female WT mice (P between sex and genotype <0.05; both). In conclusion, these data indicate that an enhanced AT(2)R-mediated pathway counterbalances the hypertensive effects of Ang II and attenuates the Ang II-dependent resetting of TGF activity in females. Thus, the enhancement of the AT(2)R may, in part, underlie the protection that premenopausal women demonstrate against cardiovascular disease.

Renin angiotensin system and gender differences in dopaminergic degeneration

BACKGROUND

There are sex differences in dopaminergic degeneration. Men are approximately two times as likely as premenopausal women of the same age to develop Parkinson's disease (PD). It has been shown that the local renin angiotensin system (RAS) plays a prominent role in sex differences in the development of chronic renal and cardiovascular diseases, and there is a local RAS in the substantia nigra and dopaminergic cell loss is enhanced by angiotensin via type 1 (AT1) receptors.

RESULTS

In the present study, we observed that intrastriatal injection of 6-hydroxydopamine induced a marked loss of dopaminergic neurons in the substantia nigra of male rats, which was significantly higher than the loss induced in ovariectomized female rats given estrogen implants (i.e. rats with estrogen). However, the loss of dopaminergic neurons was significantly lower in male rats treated with the AT1 antagonist candesartan, and similar to that observed in female rats with estrogen. The involvement of the RAS in gender differences in dopaminergic degeneration was confirmed with AT1a-null mice lesioned with the dopaminergic neurotoxin MPTP. Significantly higher expression of AT1 receptors, angiotensin converting enzyme activity, and NADPH-oxidase complex activity, and much lower levels of AT2 receptors were observed in male rats than in female rats with estrogen.

CONCLUSIONS

The results suggest that brain RAS plays a major role in the increased risk of developing PD in men, and that manipulation of brain RAS may be an efficient approach for neuroprotective treatment of PD in men, without the feminizing effects of estrogen.

Identification of cathepsin L as a potential sex-specific biomarker for renal damage

The renin-angiotensin system is a well-known regulator of blood pressure and plays an important role in the pathogenesis of cardiovascular disease and renal damage. Genetic factors, including single nucleotide polymorphisms and sex, are increasingly recognized as potential risk factors for the development of cardiovascular disease. Double transgenic rats (dTGRs), harboring human renin and angiotensinogen genes, were used in this study to investigate potential sex differences influencing renal function and renal gene expression. dTGR males and females had comparable increases in blood pressure, whereas body weight, albuminuria/proteinuria, and urine flow rate were higher in males. At 8 weeks of age, renal plasma flow and glomerular filtration rate were proportionally lower in males, and renal vascular resistance tended to be higher. Males developed more severe tubulointerstitial and vascular lesions. By the end of week 8, 40%of the males but none of the females had died. Genome expression studies were performed with RNA from kidneys of 7-week-old male and female dTGRs and control rats to further investigate the sex-related differences on a molecular level. Forty-five genes showed sex-dependent expression patterns in dTGRs that were significantly different compared to controls. Cathepsin L, one of the genes differentially expressed between the sexes, was also shown to be strongly associated with the degree of renal injury. In dTGRs, urinary cathepsin L at week 7 was higher in males (nanograms per 24 hours: male, 512±163; female, 132±70). These results reveal a potential new biomarker for the personalized diagnosis and management of chronic kidney disease.

Sex differences in renal angiotensin converting enzyme 2 (ACE2) activity are 17β-oestradiol-dependent and sex chromosome-independent

Background

Angotensin converting enzyme 2 (ACE2) is a newly discovered monocarboxypeptidase that counteracts the vasoconstrictor effects of angiotensin II (Ang II) by converting Ang II to Ang-(1-7) in the kidney and other tissues.

Methods

ACE2 activity from renal homogenates was investigated by using the fluorogenic peptide substrate Mca-YVADAPK(Dnp)-OH, where Mca is (7-methoxycoumarin-4-yl)-acetyl and Dnp is 2,4-dinitrophenyl.

Results

We found that ACE2 activity expressed in relative fluorescence units (RFU) in the MF1 mouse is higher in the male (M) compared to the female (F) kidney [ACE2 (RFU/min/μg protein): M 18.1 ± 1.0 versus F 11.1 ± 0.39; P < 0.0001; n = 6]. Substrate concentration curves revealed that the higher ACE2 activity in the male was due to increased ACE2 enzyme velocity (V_max) rather than increased substrate affinity (K_m). We used the four core genotypes mouse model in which gonadal sex (ovaries versus testes) is separated from the sex chromosome complement enabling comparisons among XX and XY gonadal females and XX and XY gonadal males. Renal ACE2 activity was greater in the male than the female kidney, regardless of the sex chromosome complement [ACE2 (RFU/min/μg protein): intact-XX-F, 7.59 ± 0.37; intact-XY-F, 7.43 ± 0.53; intact-XX-M, 12.1 ± 0.62; intact-XY-M, 12.7 ± 1.5; n = 4-6/group; P < 0.0001, F versus M, by two-way ANOVA]. Enzyme activity was increased in gonadectomized (GDX) female mice regardless of the sex chromosome complement whereas no effect of gonadectomy was observed in the males [ACE2 (RFU/min/μg protein): GDX-XX-F, 12.4 ± 1.2; GDX-XY-F, 11.1 ± 0.76; GDX-XX-M, 13.2 ± 0.97; GDX-XY-M, 11.6 ± 0.81; n = 6/group]. 17β-oestradiol (E₂) treatment of GDX mice resulted in ACE2 activity that was only 40% of the activity found in the GDX mice, regardless of their being male or female, and was independent of the sex chromosome complement [ACE2 (RFU/min/μg protein): GDX+E₂-XX-F, 5.56 ± 1.0; GDX+E₂-XY-F, 4.60 ± 0.52; GDX+E₂-XX-M, 5.35 ± 0.70; GDX+E₂-XY-M, 5.12 ± 0.47; n = 6/group].

Conclusions

Our findings suggest sex differences in renal ACE2 activity in intact mice are due, at least in part, to the presence of E₂ in the ovarian hormone milieu and not to the testicular milieu or to differences in sex chromosome dosage (2X versus 1X; 0Y versus 1Y). E₂ regulation of renal ACE2 has particular implications for women across their life span since this hormone changes radically during puberty, pregnancy and menopause.

Metabolic syndrome and the development of chronic kidney disease among 118 924 non-diabetic Taiwanese in a retrospective cohort

AIM

Metabolic syndrome (MetS) is a common risk factor for cardiovascular and chronic kidney disease (CKD) in Western populations; however, no prospective studies have examined MetS as a risk factor for CKD in Chinese adults.

METHODS

The incidence of CKD and the prospective link between MetS (defined by two criteria: modified Adult Treatment Panel III (ATP-III) and the International Diabetes Federation (IDF)) and CKD among 118,924 Taiwanese participants without baseline diabetes, aged 20-74 years with a mean 3.7 years follow up, was examined. CKD was measured by using estimated glomerular filtration rate or dipstick proteinuria (1+). The association between MetS or combination patterns of MetS abnormalities and CKD was evaluated using Cox models with adjustment for confounders.

RESULTS

The incidence of CKD was 288/10,000 person-years (95% confidence interval (CI), 283-293). The findings showed that central obesity (OB), high blood pressure (BP) and high triglyceride were considered to be the major metabolic events in the study cohort. Incidences and hazard ratios (HR) on CKD had evidently increasing trends with the number of MetS components. The multivariable-adjusted HR for CKD associated with ATP-III-MetS was 1.30 (95% CI, 1.24-1.36). Equivalent HR for IDF-MetS were 1.37 (95% CI, 1.30-1.44). The associations were still observed when analyzing by stratifying incident diabetes and adjusting hypertension status.

CONCLUSION

MetS induces an increased risk for CKD independent of baseline confounding factors and subsequent incident diabetes modified the associations lightly. The mechanism through which MetS may cause CKD in this population likely is the development of multiple metabolic pathogenic processes together.

Sex differences in acute ANG II-mediated hemodynamic responses in mice

Male sex is associated with higher blood pressure and greater renal injury, perhaps related to greater sensitivity to ANG II. In anesthetized male and female C57BLK/6 mice, we assessed responses of mean arterial pressure (MAP) and renal vascular resistance (RVR; Transonic flow probe) to acute bolus injections of ANG II (0.3-3.0 microg/kg iv) and phenylephrine (PE; 30-300 microg/kg) during low-, normal-, and high-sodium diets. The role of reactive oxygen species was determined by coadministration of tempol. ANG II type 1 and type 2 (AT1 and AT2) receptor and endothelial nitric oxide synthase (NOS3) expression were determined in dissected kidney vessels. While no difference was found on the low-sodium (LS) diet, MAP and RVR responses to ANG II were greater in males during the normal-sodium (NS) and high-sodium (HS) diets (e.g., RVR response at ANG II 3.0 microg/kg during NS: +329 +/- 22 vs. +271 +/- 28 mmHg.ml(-1).min, P = 0.029, effect size = 0.75). Tempol had no effect on the sex-dependent responses on any of the diets. On the LS diet, AT1 and AT2 receptor expression was higher in males. No sex differences were found on the NS diet. On the HS diet, AT1 was higher, and NOS3 expression was lower in males. Acute responses to ANG II are greater in male mice during NS and HS diets, which is, in part, related to differences in AT1, AT2, and NOS3 expression in kidney vessels. Mouse models will be useful to study the role of sex differences in ANG II sensitivity for cardiovascular and renal disease.

Effects of estradiol on renal cyclic guanosine monophosphate and oxidative stress in spontaneously hypertensive rats

BACKGROUND

Evidence suggests that estradiol offers protection against the development of cardiovascular and renal pathologies, although the mechanisms involved are still under investigation. The nitric oxide (NO) pathway regulates blood pressure and kidney function, and estradiol is associated with increases in NO bioavailability. We hypothesized that in female spontaneously hypertensive rats (SHRs), estra-diol increases NO bioavailability, activates the NO synthase (NOS) pathway, and suppresses superoxide production compared with rats that underwent ovariectomy (OVX).

OBJECTIVE

The goal of this study was to determine whether estradiol regulates the NO/cyclic guanosine monophosphate (cGMP) pathway and superoxide levels in the kidneys of female SHR.

METHODS

Three types of SHRs were studied: gonad-intact females, OVX rats, and OVX rats with estra-diol replacement (OVX+E). Renal cortical cGMP levels were measured to assess NO bioavailability. NOS enzymatic activity, NOS protein expression, basal superoxide production, and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity were measured in the renal cortex.

RESULTS

Fifty-six SHRs were included in the study (17 intact females, 21 OVX rats, 18 OVX+E rats). Mean (SEM) cGMP levels were significantly lower in the renal cortex of OVX rats (0.03 [0.008] pmol/mg, n = 5) than in intact females (0.1 [0.02] pmol/mg, n = 6; P < 0.05), and estradiol restored cGMP levels to those seen in intact females (0.1 [0.01] pmol/mg, n = 5; P < 0.05). Despite a decrease in cGMP following OVX, renal cortical NOS activity, NOS1 and NOS3 protein expression, and the phosphorylation status of NOS3 were comparable among the 3 groups (n = 7-9 per group). However, mean basal superoxide production in the renal cortex was higher in OVX rats (3.2 [0.3] cpm/mg, n = 12) than in intact females (1.9 [0.3] cpm/mg, n = 8; P < 0.05) and lower in OVX+E rats (1.3 [0.3] cpm/mg, n = 9; P < 0.05). Mean NADPH oxidase activity was comparable in the renal cortex of intact females and OVX rats (81 [4] and 83 [12] cpm/35 microg, respectively [n = 5 per group]). OVX+E rats had significantly lower mean renal cortical NADPH oxidase activity than did rats in the other groups (45 [6] cpm/35 microg, n = 6; P < 0.05), and the decrease in activity was accompanied by a decrease in p22(phox) protein expression.

CONCLUSIONS

In vivo manipulations of estradiol levels influenced renal cortical NO bioavailability, as assessed indirectly by cGMP measurements. The decrease in cGMP following OVX was not due to alterations in the activity or expression of NOS.

Sex differences in the developmental origins of hypertension and cardiorenal disease

The "developmental origins of health and disease" (DOHAD) hypothesis derives from clinical observations, indicating long-term health consequences for persons of low birth weight. There is growing evidence, primarily from animal studies, that supports the idea that processes put in motion during development that contribute to DOHAD do not necessarily reflect as significantly compromised growth and altered birth weight. Throughout the body of work investigating the DOHAD hypothesis, several themes have emerged; the importance of the placenta, the presence of critical periods of vulnerability, the involvement of the kidney in programmed hypertension, the presence of sex differences in the progression and development of adult diseases. Despite compelling findings in recent studies, much remains unclear regarding the impact of biological sex in the progression of human diseases, in general, and in the mechanisms underlying developmentally programmed responses, in particular. Although the contribution of biological sex to DOHAD is increasingly recognized, it also appears that it may exert distinctly different influences during fetal and adult life. The mechanisms by which biological sex contributes to these processes remains nebulous at present; nevertheless, several intriguing mechanistic candidates have been proposed ranging from differences in the amounts of sex hormones (e.g., estrogens, androgens) to recently described sexual dimorphism in the transcriptome of a variety of mammalian tissues. Recognizing the influences of biological sex or sex hormones on DOHAD uniquely situates research in this area to provide significant insights into the development and progression of many diseases, recent examples of which are the subject of this review.

[Difference in urine concentration according to gender and ethnicity: possible involvement in the different susceptibility to various renal and cardiovascular diseases]

Men and African-Americans are known to be at greater risk of urolithiasis and cardiovascular and renal diseases than women and Caucasians. Previous studies suggest that the antidiuretic effects of vasopressin and/or a greater urine concentration are associated with the rate of progression of these diseases. The present review addresses possible sex and ethnic-related differences in urine volume and osmolality which could participate in this male and black higher predominance. We reanalyzed 24h-urine data collected previously by different investigators for other purposes. In studies concerning healthy subjects (six studies) or patients with chronic kidney disease or Diabetes mellitus (three studies), men excreted a larger osmolar load than women, with a 15 to 30% higher urinary osmolality (or another index of urine concentration based on the urine/plasma creatinine concentration ratio) and a similar 24h urine volume than in women. In two American studies, African-Americans showed a significantly higher urinary concentration than Caucasians and a lower 24h-urine volume. Sex and ethnic differences in thirst threshold, vasopressin level, or other regulatory mediators may contribute to the higher urinary concentration of men and of African Americans. These differences could play a role in the greater susceptibility of these subjects to these pathologies. New prospective studies should take into account the antidiuretic effects of vasopressin as a potential risk factor in the initiation and progression of cardiovascular and renal diseases.

Sex and the renin-angiotensin system: inequality between the sexes in response to RAS stimulation and inhibition

The purpose of this review is to examine sex differences in response to stimulation and inhibition of the renin-angiotensin system (RAS). The RAS plays a prominent role in the development of chronic renal disease, and there are known sex differences not only in the expression level of components of the RAS but also in how males and females respond to perturbations of the RAS. In men, renal injury increases in parallel with increased activation of the RAS, while in women, increases in ANG II do not necessarily translate into increases in renal injury. Moreover, both epidemiological and experimental studies have noted sex differences in the therapeutic benefits following angiotensin-converting enzyme inhibitor and angiotensin receptor blocker treatment. Despite these differences, RAS inhibitors are the most commonly prescribed drugs for the treatment of chronic renal disease, irrespective of sex. This review will examine how males and females respond to stimulation and inhibition of the RAS, with a focus on renal disease.

Sex and sex hormones influence the development of albuminuria and renal macrophage infiltration in spontaneously hypertensive rats

There is a sex difference in hypertensive renal injury, with men experiencing greater severity and a more rapid progression of renal disease than women; however, the molecular mechanisms protecting against renal injury in women are unknown. The goal of this study was to determine whether sex hormones modulate blood pressure and the progression of albuminuria during the developmental phase of hypertension in male and female spontaneously hypertensive rats (SHR). Studies were also performed to examine how sex and sex hormones influence two major risk factors for albuminuria, overactivation of the renin-angiotensin system and oxidative stress. Blood pressure was measured by telemetry in gonad-intact and gonadectomized male and female SHR. Microalbumin excretion, measured over time, and macrophage infiltration were used to assess renal health. Male SHR had significantly higher blood pressures than female SHR, and gonadectomy decreased blood pressures in males with no effect in females. Male SHR displayed a gonad-sensitive increase in albuminuria over time, and female SHR had a gonad-sensitive suppression in macrophage infiltration. Female SHR had greater plasma ANG II levels and similar levels of renal cortical ANG II vs. levels shown in males but less AT(1)-receptor protein expression in the renal cortex. Female SHR also had a gonad-sensitive decrease in renal oxidative stress. Therefore, the renal protection afforded to female SHR is associated with lower blood pressure, decreased macrophage infiltration, and decreased levels of oxidative stress.