Tissue-specific regulation of ACE/ACE2 and AT1/AT2 receptor gene expression by oestrogen in apolipoprotein E/oestrogen receptor-alpha knock-out mice

Sex and sex steroids as determinants of cardiovascular risk

There are considerable sex differences regarding the risk of cardiovascular disease (CVD), including arterial hypertension, coronary artery disease (CAD) and stroke, as well as chronic renal disease. Women are largely protected from these conditions prior to menopause, and the risk increases following cessation of endogenous estrogen production or after surgical menopause. Cardiovascular diseases in women generally begin to occur at a later age than in men (on average with a delay of 10 years). Cessation of estrogen production also impacts metabolism, increasing the risk of developing obesity and diabetes. In middle-aged individuals, hypertension develops earlier and faster in women than in men, and smoking increases cardiovascular risk to a greater degree in women than it does in men. It is not only estrogen that affects female cardiovascular health and plays a protective role until menopause: other sex hormones such as progesterone and androgen hormones generate a complex balance that differentiates heart and blood vessel function in women compared to men. Estrogens improve vasodilation of epicardial coronary arteries and the coronary microvasculature by augmenting the release of vasodilating factors such as nitric oxide and prostacyclin, which are mechanisms of coronary vasodilatation that are more pronounced in women compared to men. Estrogens are also powerful inhibitors of inflammation, which in part explains their protective effects on CVD and chronic renal disease. Emerging evidence suggests that sex chromosomes also play a significant role in shaping cardiovascular risk. The cardiovascular protection conferred by endogenous estrogens may be extended by hormone therapy, especially using bioidentical hormones and starting treatment early after menopause.

The Molecular Basis of the Augmented Cardiovascular Risk in Offspring of Mothers with Hypertensive Disorders of Pregnancy

The review examines the impact of maternal preeclampsia (PE) on the cardiometabolic and cardiovascular health of offspring. PE, a hypertensive disorder of pregnancy, is responsible for 2 to 8% of pregnancy-related complications. It significantly contributes to adverse outcomes for their infants, affecting the time of birth, the birth weight, and cardiometabolic risk factors such as blood pressure, body mass index (BMI), abdominal obesity, lipid profiles, glucose, and insulin. Exposure to PE in utero predisposes offspring to an increased risk of cardiometabolic diseases (CMD) and cardiovascular diseases (CVD) through mechanisms that are not fully understood. The incidence of CMD and CVD is constantly increasing, whereas CVD is the main cause of morbidity and mortality globally. A complex interplay of genes, environment, and developmental programming is a plausible explanation for the development of endothelial dysfunction, which leads to atherosclerosis and CVD. The underlying molecular mechanisms are angiogenic imbalance, inflammation, alterations in the renin-angiotensin-aldosterone system (RAAS), endothelium-derived components, serotonin dysregulation, oxidative stress, and activation of both the hypothalamic-pituitary-adrenal axis and hypothalamic-pituitary-gonadal axis. Moreover, the potential role of epigenetic factors, such as DNA methylation and microRNAs as mediators of these effects is emphasized, suggesting avenues for future research and therapeutic interventions.

Estrogen-mediated mechanisms in hypertension and other cardiovascular diseases

Cardiovascular disease (CVD) is the leading cause of death globally for men and women. Premenopausal women have a lower incidence of hypertension and other cardiovascular events than men of the same age, but diminished sex differences after menopause implicates 17-beta-estradiol (E2) as a protective agent. The cardioprotective effects of E2 are mediated by nuclear estrogen receptors (ERα and ERβ) and a G protein-coupled estrogen receptor (GPER). This review summarizes both established as well as emerging estrogen-mediated mechanisms that underlie sex differences in the vasculature during hypertension and CVD. In addition, remaining knowledge gaps inherent in the association of sex differences and E2 are identified, which may guide future clinical trials and experimental studies in this field.

Impact of puberty, sex determinants and chronic inflammation on cardiovascular risk in young people

Worrying trends of increased cardiovascular disease (CVD) risk in children, adolescents and young people in the Modern Era have channelled research and public health strategies to tackle this growing epidemic. However, there are still controversies related to the dynamic of the impact of sex, age and puberty on this risk and on cardiovascular health outcomes later in life. In this comprehensive review of current literature, we examine the relationship between puberty, sex determinants and various traditional CVD-risk factors, as well as subclinical atherosclerosis in young people in general population. In addition, we evaluate the role of chronic inflammation, sex hormone therapy and health-risk behaviours on augmenting traditional CVD-risk factors and health outcomes, ultimately aiming to determine whether tailored management strategies for this age group are justified.

Appraising the Preclinical Evidence of the Role of the Renin-Angiotensin-Aldosterone System in Antenatal Programming of Maternal and Offspring Cardiovascular Health Across the Life Course: Moving the Field Forward: A Scientific Statement From the American Heart Association

There is increasing interest in the long-term cardiovascular health of women with complicated pregnancies and their affected offspring. Emerging antenatal risk factors such as preeclampsia appear to increase the risk of hypertension and cardiovascular disease across the life course in both the offspring and women after pregnancy. However, the antenatal programming mechanisms responsible are complex and incompletely understood, with roots in alterations in the development, structure, and function of the kidney, heart, vasculature, and brain. The renin-angiotensin-aldosterone system is a major regulator of maternal-fetal health through the placental interface, as well as kidney and cardiovascular tissue development and function. Renin-angiotensin-aldosterone system dysregulation plays a critical role in the development of pregnancy complications such as preeclampsia and programming of long-term adverse cardiovascular health in both the mother and the offspring. An improved understanding of antenatal renin-angiotensin-aldosterone system programming is crucial to identify at-risk individuals and to facilitate development of novel therapies to prevent and treat disease across the life course. Given the inherent complexities of the renin-angiotensin-aldosterone system, it is imperative that preclinical and translational research studies adhere to best practices to accurately and rigorously measure components of the renin-angiotensin-aldosterone system. This comprehensive synthesis of preclinical and translational scientific evidence of the mechanistic role of the renin-angiotensin-aldosterone system in antenatal programming of hypertension and cardiovascular disease will help (1) to ensure that future research uses best research practices, (2) to identify pressing needs, and (3) to guide future investigations to maximize potential outcomes. This will facilitate more rapid and efficient translation to clinical care and improve health outcomes.

Impacts of COVID-19 in Breast Cancer: From Molecular Mechanism to the Treatment Approach

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has already infected more than 272 million people, resulting in 5.3 million deaths worldwide from COVID-19. Breast tumors are considered the world's most commonly diagnosed cancer. Both breast cancer and COVID-19 share common pathogenic features, represented by inflammatory mediators and the potential of SARS-CoV-2 replication in metastatic cancer cells. This may intensify viral load in patients, thereby triggering severe COVID-19 complications. Thus, cancer patients have a high risk of developing severe COVID-19 with SARS-CoV-2 infection and a higher rate of complications and death than non-cancer patients. The present review discusses common mechanisms between COVID-19 and breast cancer and the particular susceptibility to COVID-19 in breast cancer patients. We describe the effects of chemotherapeutic agents that are used against this cancer, which should be considered from the perspective of susceptibility to SARS-CoV-2 infection and risk of developing severe events. We also present potential drug interactions between chemotherapies that are used to treat breast cancer and drugs that are applied for COVID-19. The drugs that are identified as having the most interactions are doxorubicin and azithromycin. Both drugs can interact with each other and with other drugs, which likely requires additional drug monitoring and changes in drug dosage and timing of administration. Further clinical and observational studies involving breast cancer patients who acquire COVID-19 are needed to define the best therapeutic approach when considering the course of both diseases.

Similarities between maternal and fetal RR interval tachograms and their association with fetal development

An association between maternal and fetal heart rate (HR) has been reported but, so far, little is known about its physiological implication and importance relative to fetal development. Associations between both HRs were investigated previously by performing beat-by-beat coupling analysis and correlation analysis between average maternal and fetal HRs. However, studies reporting on the presence of similarities between maternal and fetal HRs or RR intervals (RRIs) over the short term (e.g., 5-min) at different gestational ages (GAs) are scarce. Here, we demonstrate the presence of similarities in the variations exhibited by maternal and fetal RRl tachograms (RRITs). To quantify the same similarities, a cross-correlation (CC) analysis between resampled maternal and fetal RRITs was conducted; RRITs were obtained from non-invasive electrocardiogram (ECG). The degree of similarity between maternal and fetal RRITs (bmfRRITs) was quantified by calculating four CC coefficients. CC analysis was performed for a total of 330 segments (two 5-min segments from 158 subjects and one 5-min from 14 subjects). To investigate the association of the similarity bmfRRITs with fetal development, the linear correlation between the calculated CC coefficients and GA was calculated. The results from the latter analysis showed that similarities bmfRRITs are common occurrences, they can be negative or positive, and they increase with GA suggesting the presence of a regulation that is associated with proper fetal development. To get an insight into the physiological mechanisms involved in the similarity bmfRRITs, the association of the same similarity with maternal and fetal HR variability (HRV) was investigated by comparing the means of two groups in which one of them had higher CC values compared to the other. The two groups were created by using the data from the 158 subjects where fetal RRI (fRRI) calculation from two 5-min ECG segments was feasible. The results of the comparison showed that the maternal very low frequency (VLF) HRV parameter is potentially associated with the similarity bmfRRITs implying that maternal hormones could be linked to the regulations involved in the similarity bmfRRITs. Our findings in this study reinforce the role of the maternal intrauterine environment on fetal development.

Premenopausal and postmenopausal women during the COVID-19 pandemic

The current global COVID-19 mortality rate is estimated to be around 3.4%; however, it is dependent on age, sex, and comorbidities. Epidemiological evidence shows gender disparities in COVID-19 severity and fatality, with non-menopausal females having milder severity and better outcomes than age-matched males. However, the difference vanishes when comparing postmenopausal women with age-matched men. It has been suggested that, to some extent, this is due to the protective role of female hormones, such as anti-Müllerian hormone and oestradiol (E2), in non-menopausal women. Oestrogens have been hypothesized to be crucial in modulating viral infection and the progression of the disease via an action on immune/inflammatory responses and angiotensin-converting enzyme type 2 expression. Hence, the most likely explanation is that, because the levels of oestrogen in females after menopause decrease, oestrogen no longer offers a beneficial effect as seen in younger females. The COVID-19 pandemic has highlighted the serious negative effects arising from the state of E2 deficiency. Therefore, hormone replacement therapy gains further support as the damaging effect of the decline in ovarian function affects many biological systems, and recently with the COVID-19 pandemic, oestrogen's vital role within the immune system has become quite clear. However, additional clinical investigations regarding hormone replacement therapy are urgently needed to further verify the protective and therapeutic effects of E2 on menopausal women with COVID-19.

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.

Sex differences in electrolyte imbalances caused by SARS-CoV-2: A cross-sectional study

BACKGROUND

Since SARS-CoV-2 spread, evidence regarding sex differences in progression and prognosis of COVID-19 have emerged. Besides this, studies on patients' clinical characteristics have described electrolyte imbalances as one of the recurrent features of COVID-19.

METHODS

We performed a cross-sectional study on all patients admitted to the emergency department (ED) from 1 March to 31 May 2020 who had undergone a blood gas analysis and a nasopharyngeal swab test for SARS-CoV-2 by rtPCR. We defined positive patients as cases (n = 710) and negatives as controls (n = 619), for a total number of patients of 1.329. The study was approved by the local ethics committee Area 3 Milan. Data were automatically extracted from the hospital laboratory SQL-based repository in anonymised form. We considered as outcomes potassium (K⁺ ), sodium (Na⁺ ), chlorine (Cl^- ) and calcium (Ca⁺⁺ ) as continuous and as categorical variables, in their relation with age, sex and SARS-CoV-2 infection status.

RESULTS

We observed a higher prevalence of hypokalaemia among patients positive for SARS-CoV-2 (13.7% vs 6% of negative subjects). Positive patients had a higher probability to be admitted to the ED with hypokalaemia (OR 2.75, 95% CI 1.8-4.1, P < .0001) and women were twice as likely to be affected than men (OR 2.43, 95% CI 1.67-3.54, P < .001). Odds ratios for positive patients to manifest with an alteration in serum Na⁺ was (OR 1.6, 95% CI 1.17-2.35, P < .001) and serum chlorine (OR 1.6, 95% CI 1.03-2.69, P < .001). Notably, OR for positive patients to be hypocalcaemic was 7.2 (95% CI 4.8-10.6, P < .0001) with a low probability for women to be hypocalcaemic (OR 0.63, 95% CI 0.4-0.8, P = .005).

CONCLUSIONS

SARS-CoV-2 infection is associated with a higher prevalence of hypokalaemia, hypocalcaemia, hypochloraemia and sodium alterations. Hypokalaemia is more frequent among women and hypocalcaemia among men.

Feminising hormone therapy reduces testicular ACE-2 receptor expression: Implications for treatment or prevention of COVID-19 infection in men

It has been proposed that men hospitalised with COVID-19 be treated with oestrogen or progesterone to improve COVID-19 outcomes. Transgender women (male-to-female) are routinely treated with oestrogen or oestrogen +progesterone for feminisation which provides a model for the effect of feminising hormones on testicular tissue. Our goal was to analyse differences in ACE-2 expression in testicles of trans-women taking oestrogen or oestrogen +progesterone. Orchiectomy specimens were collected from trans-women undergoing gender-affirming surgery, who were taking oestrogen or oestrogen+progesterone preoperatively. For controls, we used benign orchiectomy specimens from cis-gender men. All specimens were stained with H&E, Trichrome (fibrosis), insulin-like 3 antibody (Leydig cell) and ACE-2 IHC. Cells per high-powered field were counted by cell type (Leydig, Sertoli and Germ). Stain intensity was rated on a 0-2 scale. On immunohistochemistry staining for Leydig cells and ACE-2 staining, the oestrogen+progesterone cohort had fewer Leydig cells compared with controls. The oestrogen+progesterone cohort also had greater degree of tissue fibrosis compared with controls and the oestrogen cohort. This work supports the hopeful possibility that a short course of progesterone (or oestrogen+progesterone) could downregulate ACE-2 to protect men from COVID-19 infection.

Benefits of the Phytoestrogen Resveratrol for Perimenopausal Women

Endometriosis, characterized by macroscopic lesions in the ovaries, is a serious problem for women who desire conception. Damage to the ovarian cortex is inevitable when lesions are removed via surgery, which finally decreases the ovarian reserve, thereby accelerating the transition to the menopausal state. Soon after cessation of ovarian function, in addition to climacteric symptoms, dyslipidemia and osteopenia are known to occur in women aged >50 years. Epidemiologically, there are sex-related differences in the frequencies of dyslipidemia, hypertension, and osteoporosis. Females are more susceptible to these diseases, prevention of which is important for healthy life expectancy. Dyslipidemia and hypertension are associated with the progression of arteriosclerosis, and arteriosclerotic changes in the large and middle blood vessels are one of the main causes of myocardial and cerebral infarctions. Osteoporosis is associated with aberrant fractures in the spine and hip, which may confine the patients to the bed for long durations. Bone resorption is accelerated by activated osteoclasts, and rapid bone remodeling reduces bone mineral density. Resveratrol, a plant-derived molecule that promotes the function and expression of the sirtuin, SIRT1, has been attracting attention, and many reports have shown that resveratrol might exert cardiovascular protective effects. Preclinical reports also indicate that it can prevent bone loss and endometriosis. In this review, I have described the possible protective effects of resveratrol against arteriosclerosis, osteoporosis, and endometriosis because of its wide-ranging functions, including anti-inflammatory and antioxidative stress functions. As ovarian function inevitably declines after 40 years, intake of resveratrol can be beneficial for women with endometriosis aged <40 years.

Role of ACE2 in pregnancy and potential implications for COVID-19 susceptibility

In times of coronavirus disease 2019 (COVID-19), the impact of severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 infection on pregnancy is still unclear. The presence of angiotensin-converting enzyme (ACE) 2 (ACE2), the main receptor for SARS-CoV-2, in human placentas indicates that this organ can be vulnerable for viral infection during pregnancy. However, for this to happen, additional molecular processes are critical to allow viral entry in cells, its replication and disease manifestation, particularly in the placenta and/or feto-maternal circulation. Beyond the risk of vertical transmission, COVID-19 is also proposed to deplete ACE2 protein and its biological actions in the placenta. It is postulated that such effects may impair essential processes during placentation and maternal hemodynamic adaptations in COVID-19 pregnancy, features also observed in several disorders of pregnancy. This review gathers information indicating risks and protective features related to ACE2 changes in COVID-19 pregnancies. First, we describe the mechanisms of SARS-CoV-2 infection having ACE2 as a main entry door and current evidence of viral infection in the placenta. Further, we discuss the central role of ACE2 in physiological systems such as the renin-angiotensin system (RAS) and the kallikrein-kinin system (KKS), both active during placentation and hemodynamic adaptations of pregnancy. Significant knowledge gaps are also identified and should be urgently filled to better understand the fate of ACE2 in COVID-19 pregnancies and the potential associated risks. Emerging knowledge will be able to improve the early stratification of high-risk pregnancies with COVID-19 exposure as well as to guide better management and follow-up of these mothers and their children.

Potential Influence of Menstrual Status and Sex Hormones on Female Severe Acute Respiratory Syndrome Coronavirus 2 Infection: A Cross-sectional Multicenter Study in Wuhan, China

BACKGROUND

Recent studies have indicated that females with coronavirus disease 2019 (COVID-19) have a lower morbidity, severe case rate, and mortality and better outcome than those of male individuals. However, the reasons remained to be addressed.

METHODS

To find the factors that potentially protect females from COVID-19, we recruited all confirmed patients hospitalized at 3 branches of Tongji Hospital (N = 1902), and analyzed the correlation between menstrual status (n = 509, including 68 from Mobile Cabin Hospital), female hormones (n = 78), and cytokines related to immunity and inflammation (n = 263), and the severity/clinical outcomes in female patients <60 years of age.

RESULTS

Nonmenopausal female patients had milder severity and better outcome compared with age-matched men (P < .01 for both). Menopausal patients had longer hospitalization times than nonmenopausal patients (hazard ratio [HR], 1.91 [95% confidence interval {CI}, 1.06-3.46]; P = .033). Both anti-Müllerian hormone (AMH) and estradiol (E2) showed a negative correlation with severity of infection (adjusted HR, 0.146 [95% CI, .026-.824], P = .029 and 0.304 [95% CI, .092-1.001], P = .05, respectively). E2 levels were negatively correlated with interleukin (IL) 2R, IL-6, IL-8, and tumor necrosis factor alpha in the luteal phase (P = .033, P = .048, P = .054, and P = .023) and C3 in the follicular phase (P = .030).

CONCLUSIONS

Menopause is an independent risk factor for female COVID-19 patients. AMH and E2 are potential protective factors, negatively correlated with COVID-19 severity, among which E2 is attributed to its regulation of cytokines related to immunity and inflammation.

ACE2, TMPRSS2 and L-SIGN expression in placentae from HIV-positive pregnancies exposed to antiretroviral therapy-implications for SARS-CoV-2 placental infection

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binding receptor ACE2 and the spike protein priming protease TMPRSS2 are coexpressed in human placentae. It is unknown whether their expression is altered in the context of HIV infection and antiretroviral therapy (ART).

Methods

We compared mRNA levels of SARS-CoV-2 cell-entry mediators ACE2, TMPRSS2, and L-SIGN by quantitative polymerase chain reaction in 105 placentae: 45 from pregnant women with HIV (WHIV) on protease inhibitor (PI)-based ART, 17 from WHIV on non-PI–based ART, and 43 from HIV-uninfected women.

Results

ACE2 levels were lower, while L-SIGN levels were higher, in placentae from WHIV on PI-based ART compared to those on non-PI–based ART and to HIV-uninfected women. TMPRSS2 levels were similar between groups. Black race was significantly associated with lower expression of ACE2 and higher expression of L-SIGN. ACE2 levels were significantly higher in placentae of female fetuses.

Conclusions

We identified pregnant women of black race and WHIV on PI-based ART to have relatively lower expression of placental ACE2 than those of white race and HIV-uninfected women. This may potentially contribute to altered susceptibility to COVID-19 in these women, favorably by reduced viral entry or detrimentally by loss of ACE2 protection against hyperinflammation.

Physiological implications of COVID-19 in reproduction: angiotensin-converting enzyme 2 a key player

The COVID-19 outbreak, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), was first identified in China, and it has quickly become a global threat to public health due to its rapid rate of transmission and fatalities. Angiotensin-converting enzyme 2 (ACE2) has been identified as a receptor that mediates the entry of SARS-CoV-2 into human cells, as in the case of severe acute respiratory syndrome coronavirus (SARS-CoV). Several studies have reported that ACE2 expression is higher in Leydig, Sertoli and seminiferous ductal cells of males, as well as in ovarian follicle cells of females, suggesting possible potential pathogenicity of the coronavirus in the reproductive system. Higher ACE2 expression in the human placenta and reports of vertical transmission of SARS-CoV-2 among clinical cases have increased the relevance of further studies in this area. This review focuses on the interaction between SARS-CoV-2 and the ACE2 receptor and speculates on the mechanistic interplay in association with male and female reproductive physiology. In addition, based on the available literature, we discuss the alleged sex differences in terms of the infectivity of SARS-CoV-2, which is claimed greater among males, and further explore the physiological role of ACE2 and 17β-oestradiol for the same.

Angiotensin II Type 2 Receptor: A Target for Protection Against Hypertension, Metabolic Dysfunction, and Organ Remodeling

The renin-angiotensin system is of vital significance not only in the maintenance of blood pressure but also because of its role in the pathophysiology of different organ systems in the body. Of the 2 Ang II (angiotensin II) receptors, the AT₁R (Ang II type 1 receptor) has been extensively studied for its role in mediating the classical functions of Ang II, including vasoconstriction, stimulation of renal tubular sodium reabsorption, hormonal secretion, cell proliferation, inflammation, and oxidative stress. The other receptor, AT₂R (Ang II type 2 receptor), is abundantly expressed in both immune and nonimmune cells in fetal tissue. However, its expression is increased under pathological conditions in adult tissues. The role of AT₂R in counteracting AT₁R function has been discussed in the past 2 decades. However, with the discovery of the nonpeptide agonist C21, the significance of AT₂R in various pathologies such as obesity, hypertension, and kidney diseases have been examined. This review focuses on the most recent findings on the beneficial effects of AT₂R by summarizing both gene knockout studies as well as pharmacological studies, specifically highlighting its importance in blood pressure regulation, obesity/metabolism, organ protection, and relevance in the treatment of coronavirus disease 2019 (COVID-19).

Gender disparity in COVID-19: Role of sex steroid hormones

The emerging pandemic of COVID-19 caused by the novel pathogenic human coronavirus SARS-CoV-2 has caused significant morbidity and mortality across the globe, prompting the scientific world to search for preventive measures to interrupt the disease process. Demographic data indicates gender-based differences in COVID-19 morbidity with better outcome amongst females. Disparity in sex-dependent morbidity and mortality in COVID-19 patients may be attributed to difference in levels of sex steroid hormones -androgens and estrogens. Evidence suggests that apart from the regulation of viral host factors, immunomodulatory and cardioprotective roles exerted by estrogen and progesterone may provide protection to females against COVID-19. Exploring the underlying mechanisms and beneficial effects of these hormones as an adjuvant to existing therapy may be a step towards improving the outcomes. This article aims to review studies demonstrating the role of sex steroidal hormones in modulating SARS-CoV-2 host factors and summarize plausible biological reasons for sex-based differences seen in COVID-19 mortality.

Assessing COVID-19 susceptibility through analysis of the genetic and epigenetic diversity of ACE2-mediated SARS-CoV-2 entry

There is considerable variation in disease course among individuals infected with SARS-CoV-2. Many of them do not exhibit any symptoms, while some others proceed to develop COVID-19; however, severity of COVID-19 symptoms greatly differs among individuals. Focusing on the early events related to SARS-CoV-2 entry to cells through the ACE2 pathway, we describe how variability in (epi)genetic factors can conceivably explain variability in disease course. We specifically focus on variations in ACE2, TMPRSS2 and FURIN genes, as central components for SARS-CoV-2 infection, and on other molecules that modulate their expression such as CALM, ADAM-17, AR and ESRs. We propose a genetic classifier for predicting SARS-CoV-2 infectivity potential as a preliminary tool for identifying the at-risk-population. This tool can serve as a dynamic scaffold being updated and adapted to validated (epi)genetic data. Overall, the proposed approach holds potential for better personalization of COVID-19 handling.

Should ACE2 be given a chance in COVID-19 therapeutics: A semi-systematic review of strategies enhancing ACE2

The severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) has resulted in almost 28 million cases of COVID-19 (Corona virus disease-2019) and more than 900000 deaths worldwide since December 2019. In the absence of effective antiviral therapy and vaccine, treatment of COVID-19 is largely symptomatic. By making use of its spike (S) protein, the virus binds to its primary human cell receptor, angiotensin converting enzyme 2 (ACE2) which is present in the pulmonary epithelial cells as well as other organs. SARS-CoV-2 may cause a downregulation of ACE2. ACE2 plays a protective role in the pulmonary system through its Mas-receptor and alamandine-MrgD-TGR7 pathways. Loss of this protective effect could be a major component of COVID-19 pathogenesis. An attractive strategy in SARS-CoV-2 therapeutics would be to augment ACE2 either directly by supplementation or indirectly through drugs which increase its levels or stimulate its downstream players. In this semi-systematic review, we have analysed the pathophysiological interplay between ACE and ACE2 in the cardiopulmonary system, the modulation of these two proteins by SARS-CoV-2, and potential therapeutic avenues targeting ACE-Ang II and ACE2-Ang (1-7) axes, that can be utilized against COVID-19 disease progression.

Angiotensin-converting enzyme as a new immunologic target for the new SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic has affected the daily lives of millions of people worldwide and had caused significant mortality; hence, the assessment of therapeutic options is of great interest. The leading cause of death among COVID-19 patients is acute respiratory distress syndrome caused by hyperinflammation secondary to cytokine release syndrome (CRS). Cytokines, such as tumor necrosis factor-α, interleukin-6, interferon-γ and interleukin-10, are the main mediators of CRS. Based on recent evidence, the angiotensin-converting enzyme (ACE) II is known to be the target of the COVID-19 spike protein, which enables the virus to penetrate human cells. ACE II also possesses an anti-inflammatory role in many pathologies such as cardiovascular disease, hypertension, diabetes mellitus and other conditions, which are the main risk factors of poor prognosis in COVID-19 infection. Changes in tissue ACE II levels are associated with many diseases and hyperinflammatory states, and it is assumed that elevated levels of ACE II could aggravate the course of COVID-19 infection. Therefore, the use of renin-angiotensin-aldosterone system inhibitors (RASis) in COVID-19 patients could be hypothetically considered, though sufficient evidence is not presented by the scientific community. In this work, based on the most recent pieces of evidence, the roles of RAS and RASi in immunologic interactions are addressed. Furthermore, the molecular and immunologic aspects of RASi and their potential significance in COVID-19 are discussed.

Immune monitoring of a child with autoimmune hepatitis and type 1 diabetes during COVID-19 infection

Immunocompromised patients may be at increased risk to develop COVID-19 during the 2019 β-coronavirus infection. We present the unique opportunity we had to monitor the liver, IL-6 and immune cell course before, during and after COVID-19 in a boy with autoimmune hepatitis (AIH) and type 1 diabetes (T1D). CD4 and CD8 T cells frequencies decreased because of prednisolone, followed by a plateauing increase whereas CD19CD20 B cell increased strongly and was unaffected by COVID-19 infection. Moreover, the percentage of activated CD8 T cells expressing HLA-DR (CD8HLA-DR) increased during COVID-19 and subsided after its clearance. Total regulatory T cells (Tregs: CD4CD25CD127FOXP3) remained stable. Although activated Tregs (CD4CD45RAFOXP3) strongly increased upon prednisolone, it decreased afterwards. Furthermore, regulatory B cells (Bregs: CD19CD20CD24CD38) declined sharply owing to prednisolone. Serum IL-6 remained undetectable at all times. We demonstrated for the first time immune monitoring in a child with AIH and T1D before, during and after COVID-19. We hypothesize that continuing with low level of prednisolone without azathioprine may have abrogated activated Tregs, Bregs and IL-6 production and therefore permitting the activation of CD8 T cells, clearing the virus.

The Role of Sex in the Risk of Mortality From COVID-19 Amongst Adult Patients: A Systematic Review

A worldwide outbreak of coronavirus disease 2019 (COVID-19), identified as being caused by the severe acute respiratory syndrome coronavirus 2 (SARS-COV-2), was classified as a Public Health Emergency of International Concern by the World Health Organisation (WHO) on January 30, 2020. Initial sex-disaggregated mortality data emerging from the Wuhan province of China identified male sex as a risk factor for increased COVID-19 mortality.   In this systematic review, we aimed to assess the role of sex in the risk of mortality from COVID-19 in adult patients through comparison of clinical markers and inflammatory indexes.   A systematic search was conducted on the following databases: PubMed, WHO COVID-19 database, Ovid MEDLINE, and Web of Science between the dates of June 15, 2020, and June 30, 2020. Key search terms used included: "sex", "gender", "SARS-COV-2", "COVID" and "mortality". We accepted the following types of studies concerning adult COVID-19 patients: retrospective cohort, observational cohort, case series, and applied research. Further studies were extracted from reference searching. The risk of bias was determined using the National Institutes of Health Quality Assessment Tool for Observational Cohort, Cross-Sectional Studies, and Case Series.  We identified a total of 16 studies published between January 2020 and June 2020 for analysis in this systematic review. Our study population consisted of 11 cohort studies, four case series, and one genetic study, including a total of 76,555 participants. Ten of the studies included in this review observed a higher risk of mortality among males compared to females, and eight of these studies found this risk to be statistically significant.    Sex-disaggregated COVID-19 mortality data identifies male patients with comorbidities as being at an increased risk of mortality worldwide. Further investigation revealed differences in immune response regulated by sex hormones, angiotensin-converting enzyme 2 (ACE2) expression, and health behaviours as contributing factors to increased risk of mortality from COVID-19 among males.    Nine out of the 16 studies included were conducted in China. In order to comprehensively assess sex-differences in the risk of mortality from COVID-19, more studies will need to be conducted worldwide. Sex-disaggregated COVID-19 data published in the medical literature is limited, however it has become evident that male sex is an important risk factor for mortality. Further exploration into the impact of sex on this pandemic is required in order to develop targeted therapies, as well as public health policies, and to prevent sex bias in treatment.

Sex differences in cardiovascular actions of the renin-angiotensin system

Cardiovascular disease (CVD) remains a worldwide public health concern despite decades of research and the availability of numerous targeted therapies. While the intrinsic physiological mechanisms regulating cardiovascular function are similar between males and females, marked sex differences have been established in terms of CVD onset, pathophysiology, manifestation, susceptibility, prevalence, treatment responses and outcomes in animal models and clinical populations. Premenopausal females are generally protected from CVD in comparison to men of similar age, with females tending to develop cardiovascular complications later in life following menopause. Emerging evidence suggests this cardioprotection in females is, in part, attributed to sex differences in hormonal regulators, such as the renin-angiotensin system (RAS). To date, research has largely focused on canonical RAS pathways and shown that premenopausal females are protected from cardiovascular derangements produced by activation of angiotensin II pathways. More recently, a vasodilatory arm of the RAS has emerged that is characterized by angiotensin-(1-7) [(Ang-(1-7)], angiotensin-converting enzyme 2 and Mas receptors. Emerging studies provide evidence for a shift towards these cardioprotective Ang-(1-7) pathways in females, with effects modulated by interactions with estrogen. Despite well-established sex differences, female comparison studies on cardiovascular outcomes are lacking at both the preclinical and clinical levels. Furthermore, there are no specific guidelines in place for the treatment of cardiovascular disease in men versus women, including therapies targeting the RAS. This review summarizes current knowledge on sex differences in the cardiovascular actions of the RAS, focusing on interactions with gonadal hormones, emerging data for protective Ang-(1-7) pathways and potential clinical implications for established and novel therapies.

Is Sex a Determinant of COVID-19 Infection? Truth or Myth?

Purpose of Review

Angiotensin-converting enzyme 2 (ACE2), a specific high-affinity angiotensin II-hydrolytic enzyme, is the vector that facilitates cellular entry of SARS-CoV-1 and the novel SARS-CoV-2 coronavirus. SARS-CoV-2, which crossed species barriers to infect humans, is highly contagious and associated with high lethality due to multi-organ failure, mostly in older patients with other co-morbidities.

Recent Findings

Accumulating clinical evidence demonstrates that the intensity of the infection and its complications are more prominent in men. It has been postulated that potential functional modulation of ACE2 by estrogen may explain the sex difference in morbidity and mortality.

Summary

We review here the evidence regarding the role of estrogenic hormones in ACE2 expression and regulation, with the intent of bringing to the forefront potential mechanisms that may explain sex differences in SARS-CoV-2 infection and COVID-19 outcomes, assist in management of COVID-19, and uncover new therapeutic strategies.

A gendered magnifying glass on COVID-19

COVID-19 pandemia is affecting Countries worldwide with a gendered death excess as being a male represents, especially in the 50-69 years age group, an unfavourable factor. Females are constitutionally prone to defend themselves against pathogens with a stronger efficiency than males. As a fact, several genes involved into the regulation of the innate and adaptive immune response are strategically placed on the X-chromosome and, among them, pathogen-related receptors (PRRs), such as Toll-like receptor 7, suitable to recognize ssRNAs and trigger a gendered successful anti-viral fight. On the other hand, a more regulated IL-6 production and a more contained inflammation after the encounter of a pathogen supply score points in favour of the female sex in the view that an abnormal and exaggerated cytokine release does represent the hallmark of the deathful SARS-CoV-2 infection. The sex-prevalent expression of the attachment and permissive molecules ACE2 and TMPRSS2 further supports the concept of a male-oriented vulnerability. In this review, the possible role of biological and immunological sex differences into the higher morbidity and mortality of SARS-CoV-2 between females and males are discussed.

The Resilient Child: Sex-Steroid Hormones and COVID-19 Incidence in Pediatric Patients

Coronavirus disease–2019 (COVID-19), a disease caused by Severe Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, has become an unprecedented global health emergency, with fatal outcomes among adults of all ages in the United States, and the highest incidence and mortality in adult men. As the pandemic evolves there is limited understanding of a potential association between symptomatic viral infection and age. To date, there is no knowledge of the role children (prepubescent, ages 9-13 years) play as “silent” vectors of the virus, with themselves being asymptomatic. Throughout different time frames and geographic locations, the current evidence on COVID-19 suggests that children are becoming infected at a significantly lower rate than other age groups—as low as 1%. Androgens upregulate the protease TMPRSS2 (type II transmembrane serine protease-2), which facilitates efficient virus-host cell fusion with the epithelium of the lungs, thus increasing susceptibility to SARS-CoV-2 infection and development of severe COVID-19. Owing to low levels of steroid hormones, prepubertal children may have low expression of TMPRSS2, thereby limiting the viral entry into host cells. As the world anticipates a vaccine against SARS-CoV-2, the role of prepubescent children as vectors transmitting the virus must be interrogated to prepare for a potential resurgence of COVID-19. This review discusses the current evidence on the low incidence of COVID-19 in children and the effect of sex-steroid hormones on SARS-CoV-2 viral infection and clinical outcomes of pediatric patients. On reopening society at large, schools will need to implement heightened health protocols with the knowledge that children as the “silent” viral transmitters can significantly affect the adult populations.

Racial and Gender-Based Differences in COVID-19

The novel coronavirus disease (COVID-19) has become a global health crisis since its first appearance in Wuhan, China. Current epidemiological studies suggest that COVID-19 affects older patients with multiple comorbidities, such as hypertension, obesity, and chronic lung diseases. The differences in the incidence and severity of COVID-19 are likely to be multifaceted, depending on various biological, social, and economical factors. Specifically, the socioeconomic differences and psychological impact of COVID-19 affecting males and females are essential in pandemic mitigation and preparedness. Previous clinical studies have shown that females are less susceptible to acquire viral infections and reduced cytokine production. Female patients have a higher macrophage and neutrophil activity as well as antibody production and response. Furthermore, in-vivo studies of the angiotensin-converting enzyme 2 (ACE2) showed higher expression in the kidneys of male than female patients, which may explain the differences in susceptibility and progression of COVID-19 between male and female patients. However, it remains unknown whether the expression of ACE2 differs in the lungs of male or female patients. Disparities in healthcare access and socioeconomic status between ethnic groups may influence COVID-19 rates. Ethnic groups often have higher levels of medical comorbidities and lower socioeconomic status, which may increase their risk of contracting COVID-19 through weak cell-mediated immunity. In this article, we examine the current literature on the gender and racial differences among COVID-19 patients and further examine the possible biological mechanisms underlying these differences.

Inhibition of SARS-CoV-2 entry through the ACE2/TMPRSS2 pathway: a promising approach for uncovering early COVID-19 drug therapies

AIM

The COVID-19 pandemic caused by infection with the novel coronavirus SARS-CoV-2 is urging the scientific community worldwide to intense efforts for identifying and developing effective drugs and pharmacologic strategies to treat the disease. Many of the drugs that are currently in (pre)clinical development are addressing late symptoms of the disease. This review focuses on potential pharmacologic intervention at an early stage of infection which could result in less-infected individuals and less cases with severe COVID-19 disease due to reduced virus entry into the cells.

METHOD

We scanned the literature for evidence on drugs that target the virus entry machinery into host cells and consist mainly of ACE2 and TMPRSS2, as well as other cellular molecules regulating ACE2 expression, such as ADAM-17 and calmodulin.

RESULTS

Several drugs/drug classes have been identified. Most of them are already used clinically for other indications. They include recombinant soluble ACE2, indirect ACE2 modulators (angiotensin receptor blockers, calmodulin antagonists, selective oestrogen receptor modifiers), TMPRSS2 inhibitors (camostat mesylate, nafamostat mesylate, antiandrogens, inhaled corticosteroids) and ADAM-17 enhancers (5-fluorouracil).

CONCLUSION

Several agents have potential for prophylactic and therapeutic intervention at the early stages of SARS-CoV-2 infection and COVID-19 disease and they should be urgently investigated further in appropriate preclinical models and clinical studies.

[SARS-CoV-2 pandemic and assisted reproduction]

La pandemia por el nuevo virus SARS-CoV-2 ha provocado un proceso de adaptación a la nueva situación por parte de toda de la sociedad y, con ello, los centros de reproducción asistida. Tras la fase aguda de la crisis sanitaria, en la que se redujo de forma drástica la actividad, se han reanudado los ciclos, guiados por las recomendaciones de las sociedades científicas.

En este artículo revisamos toda la información publicada respecto al virus y el sistema reproductivo, señalando la presencia de enzima convertidora de angiotensina tipo ii(angiotensin-converting enzyme 2, ACE2) en el sistema reproductivo femenino y masculino, a nivel testicular, ovárico, endometrial y a nivel embrionario. Además, realizamos un análisis comparativo entre las recomendaciones de las sociedades científicas en cuanto al cribado de la infección, las normas de funcionamiento y las medidas generales de laboratorio.

Let's talk about sex in the context of COVID-19

In recent months, the coronavirus disease 2019 (COVID-19) pandemic has sent many countries into crisis. Studies have shown that this virus causes worse outcomes and a higher mortality in men than in women. It has been recognized that sex can affect the immune response to a pathogenic agent, as well as the susceptibility for some respiratory diseases. These different responses in males and females may be related to the actions of sex hormones. Angiotensin-converting enzyme 2 (ACE2) acts as the receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19. The expression of ACE2 is influenced by sex hormones; therefore, we discuss in this article that this could be one of the reasons why COVID-19 is more prevalent in men than in women.

Hyperglycemia, hydroxychloroquine, and the COVID-19 pandemic

Coronavirus disease‐2019 (COVID‐19) infection and its severity can be explained by the concentration of glycosylated severe acute respiratory syndrome‐coronavirus 2 (SARS‐CoV‐2) viral particles in the lung epithelium, the concentration of glycosylated angiotensin‐converting enzyme receptor 2 (ACE2) in the lung epithelium, and the degree and control of the pulmonary immune response to the SARS‐CoV‐2 spike protein at approximately day 8 to 10 after symptom onset, which may be related to both. Binding of ACE2 by SARS‐CoV‐2 in COVID‐19 also suggests that prolonged uncontrolled hyperglycemia, and not just a history of diabetes mellitus, may be important in the pathogenesis of the disease. It is tempting to consider that the same mechanism acts in COVID‐19 as in SARS, where an overactive macrophage M1 inflammatory response, as neutralizing antibodies to the SARS‐CoV‐2 spike protein form at day 7 to 10, results in acute respiratory distress syndrome (ARDS) in susceptible patients. It also allows consideration of agents, such as hydroxychloroquine, which may interfere with this overly brisk macrophage inflammatory response and perhaps influence the course of the disease, in particular, those that blunt but do not completely abrogate the M1 to M2 balance in macrophage polarization, as well as viral load, which in SARS appears to be temporally related to the onset of ARDS.

(1)

Aberrant glycosylation of SARS‐CoV‐2, ACE2, and various immunoregulatory proteins such as the Fc gamma receptor may impact the severity of COVID‐19 disease.

(2)

Hyperglycemia, and not simply diabetes, may increase glycosylation of these proteins and lead to more severe COVID‐19 disease.

(3)

Agents that block glycosylation may blunt the severity of COVID‐19.

Sex-specific clinical characteristics and prognosis of coronavirus disease-19 infection in Wuhan, China: A retrospective study of 168 severe patients

To confirm the relationship between sex and the progression of Coronavirus Disease-19 (COVID-19), and its potential mechanism, among severe patients. For this retrospective study, we included 168 consecutive severe patients with pathogen-confirmed COVID-19 who were hospitalized between January 16th and February 4th, 2020, at Tongji Hospital in Wuhan, China. Clinical characteristics, laboratory parameters, and outcomes were compared and analyzed between males and females. In the present study, we analyzed 168 severe patients with COVID-19, including 86 males and 82 females, and 48 patients (28.6%) were diagnosed as critically ill. Of 86 male patients, 12.8% (11/86) died and 75.6% (65/86) were discharged; of 82 female patients, 7.3% (6/82) died and 86.6% (71/82) were discharged. Eleven laboratory parameters showed significant differences between male and female patients, and six of them were higher during the whole clinical course in patients who died than in patients who were discharged. In adjusted logistic regression analysis, males with comorbidities presented a higher risk of being critically ill than males without comorbidities (OR = 3.824, 95% CI = 1.279-11.435). However, this association attenuated to null in female patients (OR = 2.992, 95% CI = 0.937-9.558). A similar sex-specific trend was observed in the relation between age and critically ill conditions. We highlighted sex-specific differences in clinical characteristics and prognosis. Male patients appeared to be more susceptible to age and comorbidities. Sex is an important biological variable that should be considered in the prevention and treatment of COVID-19.

Androgen Receptor Blockade Differentially Regulates Blood Pressure in Growth-Restricted Versus Ovarian Deficient Rats

Low birth weight is associated with a greater prevalence of hypertension in women by age 60; yet, the mechanisms involved are unknown. We previously reported that hypertension in female growth-restricted offspring that is associated with early reproductive senescence and a shift in the testosterone-to-estradiol ratio at 12 months of age is abolished by AR (androgen receptor) blockade in conjunction with downregulation of renal AT1aR (angiotensin type 1a receptor) mRNA expression. These data suggest androgen-mediated activation of the renin-angiotensin system contributes to the pathogenesis of hypertension that develops in female growth-restricted offspring with aging. Thus, this study tested the hypothesis that androgen-mediated increased blood pressure is specific to female growth-restricted offspring. Control and growth-restricted rats underwent sham or ovariectomy at 10 months of age. Vehicle or flutamide (8 mg/kg/day; subcutaneous), an AR antagonist, was administered at 11.5 months of age for 2 weeks followed by measurement of blood pressure. Loss of ovarian hormones was associated with a 10 mm Hg increase in blood pressure in control compared with intact counterparts accompanied by a 1.8-fold increase in renal AT1aR mRNA expression. Treatment with flutamide had no effect on blood pressure or renal AT1aR mRNA expression in ovariectomized controls. Although blood pressure was significantly decreased in flutamide-treated ovariectomized growth-restricted, flutamide had no effect on the increase in renal AT1aR mRNA expression. Therefore, these findings suggest the effect of AR blockade on blood pressure is specific to intact growth-restricted offspring and that mechanisms of postmenopausal hypertension may differ between normal and low birth weight women.

Pregnancy upregulates angiotensin type 2 receptor expression and increases blood flow in uterine arteries of rats

Normal pregnancy is associated with decreased uterine vascular contraction and increased blood flow even though angiotensin II (AngII) levels are increased. AngII not only activates the angiotensin type 1 receptor (AT1R) to mediate vasoconstriction but also angiotensin type 2 receptor (AT2R) to cause vasodilation. We hypothesized that upregulation of AT2R expression and function accounts for increased uterine artery blood flow during pregnancy. Virgin, pregnant (at different days of gestation) and post-partum Sprague-Dawley rats were used to determine uterine artery hemodynamics using micro ultrasound and plasma angiotensin II levels by ELISA. Isolated uterine arteries were examined for AT1R and AT2R expression and isometric contraction/relaxation. Plasma AngII levels were steady up to mid-pregnancy, increased as pregnancy advanced, reaching a peak in late pregnancy, and then restored to pre-pregnant levels after delivery. The pattern of increase in AngII levels mirrored a parallel increase in uterine blood flow. AT1R expression did not change, but AT2R expression increased during pregnancy correlating with uterine blood flow increase. Treatment with the AT2R antagonist PD123319 reduced uterine arterial blood flow. Vasoconstriction to angiotensin II was blunted in pregnant rats. Treatment with PD123319 caused greater enhancement of AngII contraction in pregnant than virgin rats. Ex vivo exposure of estradiol to uterine arterial rings dose dependently upregulated AT2R expression, that was inhibited by estrogen receptor antagonist. These results demonstrate that elevated AngII levels during gestation induce an increase in uterine blood flow via heightened AT2R-mediated signaling. Estrogens appear to directly upregulate uterine vascular AT2R independent of any endogenous factors.

Prolonged Exposure to Alcohol Vapor Causes Change in Cardiovascular Function in Female but not in Male Rats

BACKGROUND

Alcohol abuse is a health concern worldwide. Studies have associated alcohol abuse with cardiovascular impairments. In this study, we investigated differences in the effects of chronic alcohol vapor exposure on cardiovascular function between male and female rats by using the alcohol vapor chamber method to induce alcohol addiction-like behaviors in rats.

METHODS

We exposed male and female Long-Evans rats to alcohol vapor for 14 hours, followed by ethanol withdrawal for 10 hours, for 30 consecutive days or room air (control groups). The animals underwent preparation for the surgical implantation of cannulas into femoral vessels, for allowing the assessment of the basal arterial pressure and heart rate values, baroreflex function, and autonomic activity.

RESULTS

Female control rats showed higher basal heart rate compared to male control rats. Chronic alcohol vapor inhalation reduced basal heart rate in females, but not in males; this effect was followed by an increase in the parasympathetic tone of the heart. Further, female rats subjected to alcohol vapor showed an increase in the baroreflex activity.

CONCLUSIONS

These findings suggest that females are more sensitive to chronic alcohol vapor exposure than males because they had a reduction in basal heart rate and changes in the baroreflex activity.

Regulation of blood pressure is influenced by gender: A study in obese Zucker rats

AIM

The present study determined the role of renin-angiotensin system (RAS), endothelin system, and eicosanoid system in the blood pressure (BP) regulation in male and female Zucker rats, and whether the pressor response change similarly in lean and obese animals.

MATERIAL AND METHODS

In female (f) and male (m), lean (L) and obese (O) Zucker rats (ZR) at 22 weeks old, we evaluated the role of the 3 mentioned systems using the following treatments: 1) enalapril (angiotensin I converting enzyme inhibitor), 2) the ABT-627 (endothelin receptor A (ET_A) antagonist), and 3) the 1-aminobenzotriazol (1-ABT: eicosanoid synthesis inhibitor).

KEY FINDINGS

MAP by radiotelemetry was similar and significantly higher in mOZR (120 ± 2 mm Hg) and fOZR (116 ± 4 mm Hg) (p < 0.05 vs. m-, fLZR), than mLZR (105 ± 3 mm Hg) and fLZR (106 ± 1 mm Hg), that were also similar. Enalapril reduced MAP more in mOZR (23%) and mLZR (26%), than fLZR (20%, p < 0.905 vs. mLZR) or fOZR (9%; p < 0.05 vs. other groups). After 10 days of drug-free and recovery period, ABT-627 reduced MAP in fLZR and mLZR by similar amounts (102 ± 4 to 92 ± 3 mm Hg, n = 6; p < 0.05 and 105 ± 2 vs. 92 ± 3 mm Hg, n = 6; p < 0.05, respectively), but did not affect either fOZR or mOZR. After another 10 days of drug-free and recovery period, 1-ABT reduced MAP in fOZR (116 ± 4 to 95 ± 2, n = 6; p < 0.05), and did not affect all other groups.

SIGNIFICANCE

We show that the mechanisms responsible for elevated BP in male and female OZR and LZR are different, and suggest that obesity may cause an increase in BP via different mechanisms in men and women as well.

Blunting of cardioprotective actions of estrogen in female rodent heart linked to altered expression of cardiac tissue chymase and ACE2

Background:

Diastolic dysfunction develops in response to hypertension and estrogen (E2) loss and is a forerunner to heart failure (HF) in women. The cardiac renin–angiotensin system (RAS) contributes to diastolic dysfunction, but its role with respect to E2 and blood pressure remain unclear.

Methods:

We compared the effects of ovariectomy (OVX) or sham surgery on the cardiac RAS, left ventricular (LV) structure/function, and systemic/intracardiac pressures of spontaneously hypertensive rats (SHRs: n = 6 intact and 6 OVX) and age-matched Wistar-Kyoto (WKY: n = 5 intact and 4 OVX) controls.

Results:

WKY rats were more sensitive to OVX than SHRs with respect to worsening of diastolic function, as reflected by increases in Doppler-derived filling pressures (E/e′) and reductions in myocardial relaxation (e′). This pathobiologic response in WKY rats was directly linked to increases in cardiac gene expression and enzymatic activity of chymase and modest reductions in ACE2 activity. No overt changes in cardiac RAS genes or activities were observed in SHRs, but diastolic function was inversely related to ACE2 activity.

Conclusion:

Endogenous estrogens exert a more significant regulatory role upon biochemical components of the cardiac RAS of WKY versus SHRs, modulating the lusitropic and structural components of its normotensive phenotype.

Sex-specific differences in hypertension and associated cardiovascular disease

Although intrinsic mechanisms that regulate arterial blood pressure (BP) are similar in men and women, marked variations exist at the molecular, cellular and tissue levels. These physiological disparities between the sexes likely contribute to differences in disease onset, susceptibility, prevalence and treatment responses. Key systems that are important in the development of hypertension and cardiovascular disease (CVD), including the sympathetic nervous system, the renin-angiotensin-aldosterone system and the immune system, are differentially activated in males and females. Biological age also contributes to sexual dimorphism, as premenopausal women experience a higher degree of cardioprotection than men of similar age. Furthermore, sex hormones such as oestrogen and testosterone as well as sex chromosome complement likely contribute to sex differences in BP and CVD. At the cellular level, differences in cell senescence pathways may contribute to increased longevity in women and may also limit organ damage caused by hypertension. In addition, many lifestyle and environmental factors - such as smoking, alcohol consumption and diet - may influence BP and CVD in a sex-specific manner. Evidence suggests that cardioprotection in women is lost under conditions of obesity and type 2 diabetes mellitus. Treatment strategies for hypertension and CVD that are tailored according to sex could lead to improved outcomes for affected patients.

Angiotensin II AT2 Receptors Contribute to Regulate the Sympathoadrenal and Hormonal Reaction to Stress Stimuli

Angiotensin II, through AT1 receptor stimulation, mediates multiple cardiovascular, metabolic, and behavioral functions including the response to stressors. Conversely, the function of Angiotensin II AT2 receptors has not been totally clarified. In adult rodents, AT2 receptor distribution is very limited but it is particularly high in the adrenal medulla. Recent results strongly indicate that AT2 receptors contribute to the regulation of the response to stress stimuli. This occurs in association with AT1 receptors, both receptor types reciprocally influencing their expression and therefore their function. AT2 receptors appear to influence the response to many types of stressors and in all components of the hypothalamic-pituitary-adrenal axis. The molecular mechanisms involved in AT2 receptor activation, the complex interactions with AT1 receptors, and additional factors participating in the control of AT2 receptor regulation and activity in response to stressors are only partially understood. Further research is necessary to close this knowledge gap and to clarify whether AT2 receptor activation may carry the potential of a major translational advance.

Ovariectomy modify local renin-angiotensin-aldosterone system gene expressions in the heart of ApoE (-/-) mice

AIMS

The evaluation of the local Renin-Angiotensin-Aldosterone system (RAAS) gene expressions in the heart of ovariectomized (OVX) apolipoprotein E deficient mice (ApoE).

METHODS

Four-months old C57BL/6 female mice (wild-type, wt, n=20), and ApoE female mice (n=20), were submitted to OVX or a surgical procedure without ovary removal (SHAM) and formed four groups (n=10/group): SHAM/wt, SHAM/ApoE, OVX/wt, and OVX/ApoE.

KEY FINDINGS

OVX led to greater body mass, plasma triglycerides (TG) and total cholesterol, and resulted in insulin resistance and altered RAAS gene expressions in the heart tissue. The gene expression of angiotensin-converting enzyme (ACE)-2 was lower in OVX/wt than in SHAM/wt (P=0.0004), Mas receptor (MASr) was lower in OVX/wt compared to SHAM/wt (P<0.0001). Also, angiotensin II receptor type 1 (AT1r) was higher in OVX/wt than in SHAM/wt (P=0.0229), and AT2r was lower in OVX/wt than in SHAM/wt (P=0.0121). OVX and ApoE deficiency showed interaction potentializing the insulin resistance, increasing TG levels and altering ACE and MASr gene expressions. ACE gene expression was higher in OVX/ApoE than in OVX/wt (P<0.0001), and MASr gene expression was lower in OVX/ApoE than in OVX/wt (P<0.0001).

SIGNIFICANCE

The impact of OVX on local RAAS cascade in the heart of ApoE deficient animals, besides the metabolic changes culminating with insulin resistance, involves an upregulation of renin, ACE, and AT1r gene expressions. The findings may contribute to clarify the mechanisms of development of postmenopausal hypertension and the link between RAAS and apolipoprotein E.

Sex differences in vascular physiology and pathophysiology: estrogen and androgen signaling in health and disease

Sex differences between women and men are often overlooked and underappreciated when studying the cardiovascular system. It has been long assumed that men and women are physiologically similar, and this notion has resulted in women being clinically evaluated and treated for cardiovascular pathophysiological complications as men. Currently, there is increased recognition of fundamental sex differences in cardiovascular function, anatomy, cell signaling, and pathophysiology. The National Institutes of Health have enacted guidelines expressly to gain knowledge about ways the sexes differ in both normal function and diseases at the various research levels (molecular, cellular, tissue, and organ system). Greater understanding of these sex differences will be used to steer future directions in the biomedical sciences and translational and clinical research. This review describes sex-based differences in the physiology and pathophysiology of the vasculature, with a special emphasis on sex steroid receptor (estrogen and androgen receptor) signaling and their potential impact on vascular function in health and diseases (e.g., atherosclerosis, hypertension, peripheral artery disease, abdominal aortic aneurysms, cerebral aneurysms, and stroke).

Low-dose exposure to bisphenol A in combination with fructose increases expression of genes regulating angiogenesis and vascular tone in juvenile Fischer 344 rat cardiac tissue

OBJECTIVES

Epidemiological studies report associations between exposure to the high-volume chemical and endocrine disruptor bisphenol A (BPA) and cardiovascular disorders, but there is a lack of experimental studies addressing the mechanisms of action of BPA on the cardiovascular system. In the present study, effects on markers for cardiovascular function of exposure to BPA and fructose in vivo in rat cardiac tissues, and of BPA exposure in human cardiomyocytes in vitro, were investigated.

MATERIALS

Juvenile female Fischer 344 rats were exposed to 5, 50, and 500 μg BPA/kg bodyweight/day in their drinking water from 5 to 15 weeks of age, in combination with 5% fructose. Further, cultured human cardiomyocytes were exposed to 10 nM BPA to 1 × 104 nM BPA for six hours. Expression of markers for cardiovascular function and BPA target receptors was investigated using qRT-PCR.

RESULTS

Exposure to 5 μg BPA/kg bodyweight/day plus fructose increased mRNA expression of Vegf, Vegfr2, eNos, and Ace1 in rat heart. Exposure of human cardiomyocytes to 1 × 104 nM BPA increased mRNA expression of eNOS and ACE1, as well as IL-8 and NFκβ known to regulate inflammatory response.

CONCLUSIONS

. Low-dose exposure of juvenile rats to BPA and fructose induced up-regulation of expression of genes controlling angiogenesis and vascular tone in cardiac tissues. The observed effects of BPA in rat heart were in line with our present and previous studies of BPA in human endothelial cells and cardiomyocytes. These findings may aid in understanding the mechanisms of the association between BPA exposure and cardiovascular disorders reported in epidemiological studies.

Angiotensin receptor blockade mediated amelioration of mucopolysaccharidosis type I cardiac and craniofacial pathology

Mucopolysaccharidosis type I (MPS IH) is a lysosomal storage disease (LSD) caused by inactivating mutations to the alpha-L-iduronidase (IDUA) gene. Treatment focuses on IDUA enzyme replacement and currently employed methods can be non-uniform in their efficacy particularly for the cardiac and craniofacial pathology. Therefore, we undertook efforts to better define the pathological cascade accounting for treatment refractory manifestations and demonstrate a role for the renin angiotensin system (RAS) using the IDUA^-/- mouse model. Perturbation of the RAS in the aorta was more profound in male animals suggesting a causative role in the observed gender dimorphism and angiotensin receptor blockade (ARB) resulted in improved cardiac function. Further, we show the ability of losartan to prevent shortening of the snout, a common craniofacial anomaly in IDUA^-/- mice. These data show a key role for the RAS in MPS associated pathology and support the inclusion of losartan as an augmentation to current therapies.

Effects of estrogen replacement on stress-induced cardiovascular responses via renin-angiotensin system in ovariectomized rats

The purpose of this study was to determine whether chronic estrogen replacement in ovariectomized rats inhibits the pressor response to psychological stress by attenuating the activation of the renin-angiotensin system. Female Wistar rats aged 9 wk were ovariectomized. After 4 wk, the rats were randomly assigned to be implanted subcutaneously with pellets containing either 17β-estradiol (E2) or placebo (Pla). After 4 wk of treatment, the rats underwent cage-switch stress and, in a separate experiment, a subset received an infusion of angiotensin II. The cage-switch stress rapidly elevated blood pressure (BP) and heart rate (HR) as measured by radiotelemetry in both groups. However, the BP and HR responses to the stress were significantly attenuated in the E2 group compared with the Pla group. An angiotensin II type 1 receptor blocker, losartan, given in drinking water, abolished the difference in the pressor response to stress between the two groups. Moreover, the stress-induced elevation in plasma renin activity and angiotensin II concentration was significant in the Pla group, but not in the E2 group. In addition, the expression of renin mRNA in the kidney was lower in the E2 group relative to the Pla group. Finally, we found that intravenous angiotensin II infusion increased BP and decreased HR to a similar degree in both groups. These results suggest that the inhibitory effects of estrogen on psychological stress-induced activation of the renin-angiotensin system could be at least partially responsible for the suppression of the pressor responses to psychological stress seen in estrogen-replaced ovariectomized rats.

Testosterone downregulates angiotensin II type-2 receptor via androgen receptor-mediated ERK1/2 MAP kinase pathway in rat aorta

Introduction:

Blood pressure is lower in females than males. Angiotensin II type-2 receptor (AT₂R) induces vasodilation. This study determined whether sex differences in vascular AT₂R expression occur and if androgens exert control on AT₂R expression in the vasculature.

Methods:

AT₂Rs in the aorta of male and female Sprague-Dawley rats were examined following alteration in androgen levels by gonadectomy or hormone supplementation.

Results:

AT₂R mRNA and protein expression levels were lower in the aortas of males than females. In males, testosterone withdrawal by castration significantly elevated AT₂R mRNA and protein levels and testosterone replacement restored them. In females, increasing androgen levels decreased AT₂R mRNA and protein expression and this was attenuated by androgen receptor blocker flutamide. Ex vivo, dihydrotestosterone downregulated AT₂R in endothelium-intact but not endothelium-denuded aorta. Dihydrotestosterone-induced AT₂R downregulation in isolated aorta was blocked by an androgen receptor antagonist. Furthermore, blockade of ERK1/2 but not p38 MAP kinase or TGFβ signaling with specific inhibitors abolished dihydrotestosterone-induced AT₂R downregulation.

Conclusion:

Androgens downregulate AT₂R expression levels in aorta, in vivo and ex vivo. The androgen receptor-mediated ERK1/2 MAP kinase-signaling pathway may be a key mechanism by which testosterone downregulates AT₂R expression, implicating androgens’ contributing role to gender differences in vascular AT₂R expression.

Renal water molecular diffusion characteristics in healthy native kidneys: assessment with diffusion tensor MR imaging

Background

To explore the characteristics of diffusion tensor imaging (DTI) and magnetic resonance (MR) imaging in healthy native kidneys.

Methods

Seventy-three patients without chronic kidney disease underwent DTI-MRI with spin echo-echo planar (SE-EPI) sequences accompanied by an array spatial sensitivity encoding technique (ASSET). Cortical and medullary mean, axial and radial diffusivity (MD, AD and RD), fractional anisotropy (FA) and primary, secondary and tertiary eigenvalues (λ₁, λ₂, λ₃) were analysed in both kidneys and in different genders.

Results

Cortical MD, λ₂, λ₃, and RD values were higher than corresponding medullary values. The cortical FA value was lower than the medullary FA value. Medullary λ₁ and RD values in the left kidney were lower than in the right kidney. Medullary λ₂, and λ₃ values in women were higher than those in men. Medullary FA values in women were lower than those in men. Medullary FA (r = 0.351, P = 0.002) and λ₁ (r = 0.277, P = 0.018) positively correlated with eGFR. Medullary FA (r = −0.25, P = 0.033) negatively correlated with age.

Conclusions

Renal water molecular diffusion differences exist in human kidneys and genders. Age and eGFR correlate with medullary FA and primary eigenvalue.