Androgen receptor promotes abdominal aortic aneurysm development via modulating inflammatory interleukin-1α and transforming growth factor-β1 expression

Sex Differences Define the Vulnerability to Atherosclerosis

For several decades, atherosclerosis has attracted the attention of researchers around the world. Even being a major cause of serious cardiovascular disease and events, atherosclerosis is still not fully understood. Despite the fact that the main players in the pathogenesis of atherosclerosis are well known, many mechanisms of their implementation and interactions remain unknown. The same can be said about the risk factors for atherosclerosis. Many of them are known, but exactly how they work remains to be seen. The main objective of this review is to summarize the latest data on sex as a biological variable in atherosclerosis in humans and animals; to determine what we do not still know about how sex affects the process of growth and complications of atherosclerosis. In this review, we summarized data on sex differences at 3 atherosclerotic aspects: inflammation, vascular remodeling, and plaque morphology. With all overviewed data, we came to the conclusion on the atheroprotective role of female sex.

Androgen aggravates aortic aneurysms via suppressing PD-1 in mice

Androgen has long been recognized for its pivotal role in the sexual dimorphism of cardiovascular diseases, including aortic aneurysms, a devastating vascular disease with a higher prevalence and mortality rate in men than women. However, the molecular mechanism by which androgen mediates aortic aneurysms is largely unknown. Here, we report that male but not female mice develop aortic aneurysms in response to aldosterone and high salt (Aldo-salt). We demonstrate that both androgen and androgen receptors (AR) are crucial for the sexually dimorphic response to Aldo-salt. We identify T cells expressing programmed cell death protein 1 (PD-1), an immune checkpoint molecule important in immunity and cancer immunotherapy, as a key link between androgen and aortic aneurysms. We show that intraperitoneal injection of anti-PD-1 antibody reinstates Aldo-salt-induced aortic aneurysms in orchiectomized mice. Mechanistically, we demonstrate that AR binds to the PD-1 promoter to suppress its expression in the spleen. Hence, our study reveals an important but unexplored mechanism by which androgen contributes to aortic aneurysms by suppressing PD-1 expression in T cells. Our study also suggests that cancer patients predisposed to the risk factors of aortic aneurysms may be advised to screen for aortic aneurysms during immune checkpoint therapy.

Establishment of a meta-analysis based novel aortic dissection mouse model

Aortic dissection (AD) is a life-threatening disease and the detailed mechanism remains unclear. Thus, proper animal models are urgently required to better understand its pathogenesis. Our current study aims to establish a reliable, time and cost-effective mouse AD model. To conduct the meta-analysis, we searched PubMed for related studies up to 2021 and statistical analysis was conducted using Review Manager 5.4. For the animal experiment, 6-week-old male ApoE^-/- mice were given β-aminopropionitrile (BAPN) at a concentration of 1 g/L for 3 weeks before being infused with saline, 1000 ng/kg/min or 2500 ng/kg/min angiotensin II (AngII) via osmotic mini pumps for 2 or 4 weeks. To determine the presence of AD, we performed B-ultrasonography, hematoxylin and eosin (H&E) staining, and van Gieson staining. The result of the meta-analysis showed that the use of BAPN and more than 2000 ng/kg/min AngII can increase the rate of AD formation, whereas administrating Ang II for more than 28 days has no significant effect on the rate of AD formation when compared with the less than 14 days group. In the present study, mice treated with BAPN combined with 2500 ng/kg/min AngII for 2 weeks (12/20) had a significantly higher AD formation rate than mice treated with BAPN combined with 1000 ng/kg/min Ang II for 4 weeks (2/10), and had a similar model formation rate compared with the mice treated withβ-aminopropionitrile combined with 2500 ng/kg/min AngII for 4 weeks (6/10). There were 3 mice (3/10) and 6 mice (6/20) who died in the group treated with β-aminopropionitrile combined with 2500 ng/kg/min AngII for 4 weeks and 2 weeks respectively, and only one mouse (1/10) died in the group treated with β-aminopropionitrile combined with 1000 ng/kg/min AngII for 4 weeks. In 6-week-old male ApoE^-/- mice that received with 1 g/L BAPN in the drinking water for 3 weeks along with 2500 ng/kg/min AngII infusion via osmotic mini pumps for 2 weeks, the highest model formation rate and relative lower cumulative mortality were noted.

Low Progesterone and Low Estradiol Levels Associate With Abdominal Aortic Aneurysms in Men

CONTEXT

Male sex is a major risk factor for abdominal aortic aneurysms (AAA) but few studies have addressed associations between sex hormone levels and AAA.

OBJECTIVE

We aimed to describe the associations between serum sex steroids and early, screening-detected AAA in men.

METHODS

We validated a high-sensitivity liquid chromatography-tandem mass spectrometry assay for comprehensive serum sex hormone profiling. This assay was then employed in a case-control study including 147 men with AAA (infrarenal aorta ≥ 30 mm) and 251 AAA-free controls recruited at the general population-based ultrasound screening for AAA in 65-year-old Swedish men.

OUTCOMES INCLUDED

associations between dehydroepiandrosterone, progesterone, 17α-hydroxyprogesterone, androstenedione, estrone, testosterone, dihydrotestosterone, and estradiol and AAA presence.

RESULTS

Dehydroepiandrosterone, progesterone, 17α-hydroxyprogesterone, testosterone, and estradiol, but not the other hormones, were lower in men with AAA. In models with adjustments for known AAA risk factors and comorbidity, only progesterone (odds ratio per SD decrease 1.62 [95% CI, 1.18-2.22]) and estradiol (1.40 [95% CI, 1.04-1.87]) remained inversely associated with the presence of AAA. Progesterone and estradiol contributed with independent additive information for prediction of AAA presence; compared with men with high (above median) levels, men with low (below median) levels of both hormones had a 4-fold increased odds ratio for AAA (4.06 [95% CI, 2.25-7.31]).

CONCLUSION

Measured by a high-performance sex steroid assay, progesterone and estradiol are inversely associated with AAA in men, independent of known risk factors. Future studies should explore whether progesterone and estradiol, which are important reproductive hormones in women, are protective in human AAA.

Sex Differences in Inflammation During Venous Remodeling of Arteriovenous Fistulae

Vascular disorders frequently have differing clinical presentations among women and men. Sex differences exist in vascular access for hemodialysis; women have reduced rates of arteriovenous fistula (AVF) maturation as well as fistula utilization compared with men. Inflammation is increasingly implicated in both clinical studies and animal models as a potent mechanism driving AVF maturation, especially in vessel dilation and wall thickening, that allows venous remodeling to the fistula environment to support hemodialysis. Sex differences have long been recognized in arterial remodeling and diseases, with men having increased cardiovascular events compared with pre-menopausal women. Many of these arterial diseases are driven by inflammation that is similar to the inflammation during AVF maturation. Improved understanding of sex differences in inflammation during vascular remodeling may suggest sex-specific vascular therapies to improve AVF success.

H2S alleviates aortic aneurysm and dissection: Crosstalk between transforming growth factor 1 signaling and NLRP3 inflammasome

BACKGROUND

Vascular remodeling and inflammation are involved in aortic aneurysm (AA) and aortic dissection (AD). TGF-β1 signaling is involved in tissue fibrosis, extracellular matrix remodeling and inflammation, which are linked with AA and AD. The inhibition of NLRP3 inflammasome suppresses AA and AD. Hydrogen sulfide (H₂S) exerts anti-vascular remodeling and anti-inflammatory properties, but little is known about its action on AA and AD progression.

METHODS

The effect of H₂S on AA and AD formation was investigated in Sprague-Dawley (SD) rat fed a normal diet supplemented with 0.25% β-aminopropionitrile (BAPN). HE staining, Masson's trichrome staining, Picrosirius red staining and EVG staining were to evaluate vascular remodeling in the aortic wall. Western blotting and IHC were to detect the expression of TGF-β1 and matrix metalloproteinases (MMPs) and NLRP3 inflammasome-associated proteins. The interaction between TGF-β1 signaling and NLRP3 inflammasome was explored in Human aortic vascular smooth muscle cells (HA-VSMCs).

RESULTS

H₂S alleviated AA and AD progression. Specifically, it improved irregular tissue arrangement and vascular fibrosis, increased the expression of elastin fibers, decreased collagen deposition and the expression of TGF-β1 and matrix metalloproteinases (MMP-2/9). In addition, H₂S inhibited the expression of proteins involved in NLRP3 inflammasome. Furthermore, H₂S down-regulated TGF-β1 signaling and then ameliorated vascular fibrosis by preventing NLRP3 inflammasome activation. Finally, H₂S inhibited NLRP3 inflammasome activation and decreased the level of IL-1β by disrupting TGF-β1 signaling.

CONCLUSIONS

These data support a crosstalk between TGF-β1 signaling and NLRP3 inflammasome. H₂S inhibits AA and AD progression via blocking the crosstalk.

A review of the effects and molecular mechanisms of dimethylcurcumin (ASC-J9) on androgen receptor-related diseases

Dimethylcurcumin (ASC-J9) is a curcumin analogue capable of inhibiting prostate cancer cell proliferation. The mechanism is associated with the unique role of ASC-J9 in enhancing androgen receptor (AR) degradation. So far, ASC-J9 has been investigated in typical AR-associated diseases such as prostate cancer, benign prostatic hypertrophy, bladder cancer, renal diseases, liver diseases, cardiovascular diseases, cutaneous wound, spinal and bulbar muscular atrophy, ovarian cancer and melanoma, exhibiting great potentials in disease control. In this review, the effects and molecular mechanisms of ASC-J9 on various AR-associated diseases are summarized. Importantly, the effects of ASC-J9 and AR antagonists enzalutamide/bicalutamide on prostate cancer are compared in detail and crucial differences are highlighted. At last, the pharmacological effects of ASC-J9 are summarized and the future applications of ASC-J9 in AR-associated disease control are discussed.

Androgens Accentuate TGF-β Dependent Erk/Smad Activation During Thoracic Aortic Aneurysm Formation in Marfan Syndrome Male Mice

Background Male patients with Marfan syndrome have a higher risk of aortic events and root dilatation compared with females. The role androgens play during Marfan syndrome aneurysm development in males remains unknown. We hypothesized that androgens potentiate transforming growth factor beta induced Erk (extracellular-signal-regulated kinase)/Smad activation, contributing to aneurysm progression in males. Methods and Results Aortic diameters in Fbn1C1039G/+ and littermate wild-type controls were measured at ages 6, 8, 12, and 16 weeks. Fbn1C1039G/+ males were treated with (1) flutamide (androgen receptor blocker) or (2) vehicle control from age 6 to 16 weeks and then euthanized. p-Erk1/2, p-Smad2, and matrix metalloproteinase (MMP) activity were measured in ascending/aortic root and descending aorta specimens. Fbn1C1039G/+ male and female ascending/aortic root-derived smooth muscle cells were utilized in vitro to measure Erk/Smad activation and MMP-2 activity following dihydrotestosterone, flutamide or transforming growth factor beta 1 treatment. Fbn1C1039G/+ males have increased aneurysm growth. p-Erk1/2 and p-Smad2 were elevated in ascending/aortic root specimens at age 16 weeks. Corresponding with enhanced Erk/Smad signaling, MMP-2 activity was higher in Fbn1C1039G/+ males. In vitro smooth muscle cell studies revealed that dihydrotestosterone potentiates transforming growth factor beta-induced Erk/Smad activation and MMP-2 activity, which is reversed by flutamide treatment. Finally, in vivo flutamide treatment reduced aneurysm growth via p-Erk1/2 and p-Smad2 reduction in Fbn1C1039G/+ males. Conclusions Fbn1C1039G/+ males have enhanced aneurysm growth compared with females associated with enhanced p-Erk1/2 and p-Smad2 activation. Mechanistically, in vitro smooth muscle cell studies suggested that dihydrotestosterone potentiates transforming growth factor beta induced Erk/Smad activation. As biological proof of concept, flutamide treatment attenuated aneurysm growth and p-Erk1/2 and p-Smad2 signaling in Fbn1C1039G/+ males.

Non-coding RNAs in aortic dissection: From biomarkers to therapeutic targets

Aortic dissection (AD) is the rupture of the aortic intima, causing the blood in the cavity to enter the middle of the arterial wall. Without urgent and proper treatment, the mortality rate increases to 50% within 48 hours. Most patients present with acute onset of symptoms, including sudden severe pain and complex and variable clinical manifestations, which can be easily misdiagnosed. Despite this, the molecular mechanisms underlying AD are still unknown. Recently, non‐coding RNAs have emerged as novel regulators of gene expression. Previous studies have proven that ncRNAs can regulate several cardiovascular diseases; therefore, their potential as clinical biomarkers and novel therapeutic targets for AD has aroused widespread interest. To date, several studies have reported that microRNAs are crucially involved in AD progression. Additionally, several long non‐coding RNAs and circular RNAs have been found to be differentially expressed in AD samples, suggesting their potential roles in vascular physiology and disease. In this review, we discuss the functions of ncRNAs in AD pathophysiology and highlight their potential as biomarkers and therapeutic targets for AD. Meanwhile, we present the animal models previously used for AD research, as well as the specific methods for constructing mouse or rat AD models.

Metabolism of vascular smooth muscle cells in vascular diseases

Vascular smooth muscle cells (VSMCs) are the fundamental component of the medial layer of arteries and are essential for arterial physiology and pathology. It is becoming increasingly clear that VSMCs can alter their metabolism to fulfill the bioenergetic and biosynthetic requirements. During vascular injury, VSMCs switch from a quiescent "contractile" phenotype to a highly migratory and proliferative "synthetic" phenotype. Recent studies have found that the phenotype switching of VSMCs is driven by a metabolic switch. Metabolic pathways, including aerobic glycolysis, fatty acid oxidation, and amino acid metabolism, have distinct, indispensable roles in normal and dysfunctional vasculature. VSMCs metabolism is also related to the metabolism of endothelial cells. In the present review, we present a brief overview of VSMCs metabolism and how it regulates the progression of several vascular diseases, including atherosclerosis, systemic hypertension, diabetes, pulmonary hypertension, vascular calcification, and aneurysms, and the effect of the risk factors for vascular disease (aging, cigarette smoking, and excessive alcohol drinking) on VSMC metabolism to clarify the role of VSMCs metabolism in the key pathological process.

Supraphysiological Levels of Testosterone Induce Vascular Dysfunction via Activation of the NLRP3 Inflammasome

Background: Both supraphysiological and subphysiological testosterone levels are associated with increased cardiovascular risk. Testosterone consumption at supraphysiological doses has been linked to increased blood pressure, left ventricular hypertrophy, vascular dysfunction, and increased levels of inflammatory markers. Activation of the NLRP3 inflammasome contributes to the production of proinflammatory cytokines, leading to cardiovascular dysfunction. We hypothesized that supraphysiological levels of testosterone, via generation of mitochondrial reactive oxygen species (mROS), activates the NLRP3 inflammasome and promotes vascular dysfunction. Methods: Male, 12 week-old C57Bl/6J (WT) and NLRP3 knockout (NLRP3-/-) mice were used. Mice were treated with testosterone propionate [TP (10 mg/kg) in vivo] or vehicle for 30 days. In addition, vessels were incubated with testosterone [Testo (10-6 M, 2 h) in vitro]. Testosterone levels, blood pressure, vascular function (thoracic aortic rings), pro-caspase-1/caspase-1 and interleukin-1β (IL-1β) expression, and generation of reactive oxygen species were determined. Results: Testosterone increased contractile responses and reduced endothelium-dependent vasodilation, both in vivo and in vitro. These effects were not observed in arteries from NLRP3-/- mice. Aortas of TP-treated WT mice (in vivo), as well as aortas from WT mice incubated with testo (in vitro), exhibited increased mROS levels and increased caspase-1 and IL-1β expression. These effects were not observed in arteries from NLRP3-/- mice. Flutamide [Flu, 10-5 M, androgen receptor (AR) antagonist], carbonyl cyanide m-chlorophenyl hydrazone (CCCP, 10-6 M, mitochondrial uncoupler) and MCC950 (MCC950, 10-6 M, a NLRP3 receptor inhibitor) prevented testosterone-induced mROS generation. Conclusion: Supraphysiological levels of testosterone induce vascular dysfunction via mROS generation and NLRP3 inflammasome activation. These events may contribute to increased cardiovascular risk.

The Effects of Androgens on Cardiometabolic Syndrome: Current Therapeutic Concepts

INTRODUCTION

Cardiometabolic syndrome (CMS), as a bunch of metabolic disorders mainly characterized by type 2 diabetes mellitus (T2DM), hypertension, atherosclerosis, central adiposity, and abdominal obesity triggering androgen deficiency, is one of the most critical threats to men. Although many significant preclinical and clinical findings explain CMS, new approaches toward common pathophysiological mechanisms and reasonable therapeutic targets are lacking.

AIM

To gain a further understanding of the role of androgen levels in various facets of CMS such as the constellation of cardiometabolic risk factors including central adiposity, dyslipidemia, insulin resistance, diabetes, and arterial hypertension and to define future directions for development of effective therapeutic modalities.

METHODS

Clinical and experimental data were searched through scientific literature databases (PubMed) from 2009 to October 2019.

MAIN OUTCOME MEASURE

Evidence from basic and clinical research was gathered with regard to the causal impact and therapeutic roles of androgens on CMS.

RESULTS

There are important mechanisms implicated in androgen levels and the risk of CMS. Low testosterone levels have many signs and symptoms on cardiometabolic and glycometabolic risks as well as abdominal obesity in men.

CLINICAL IMPLICATIONS

The implications of the findings can shed light on future improvements in androgen levels and add potentially predictive risk for CMS, as well as T2DM, abdominal obesity to guide clinical management in the early stage.

STRENGTHS & LIMITATIONS

This comprehensive review refers to the association between androgens and cardiovascular health. A limitation of this study is the lack of large, prospective population-based studies that analyze the effects of testosterone treatment on CMS or mortality.

CONCLUSION

Low testosterone levels have several common features with metabolic syndrome. Thus, testosterone may have preventive role in the progress of metabolic syndrome and subsequent T2DM, abdominal obesity, and cardiovascular disease and likely affect aging men's health mainly through endocrine and vascular mechanisms. Further studies are necessary to evaluate the therapeutic interventions directed at preventing CMS in men. Kirlangic OF, Yilmaz-Oral D, Kaya-Sezginer E, et al. The Effects of Androgens on Cardiometabolic Syndrome: Current Therapeutic Concepts. Sex Med 2020;8:132-155.

Nuclear receptors in abdominal aortic aneurysms

Abdominal aortic aneurysms (AAA) pose a considerable health burden and at present are only managed surgically since there is no proven pharmacotherapy that will retard their expansion or reduce the incidence of fatal rupture. This pathology shares several pathophysiological mechanisms with atherosclerosis, such as macrophage infiltration, inflammation, and degradation of extracellular matrix. Therefore, therapeutic targets proven effective in the treatment of atherosclerosis could also be considered for treatment of AAA. Different members of the nuclear receptor (NR) superfamily have been extensively studied as potential targets in the treatment of cardiovascular disease (CVD) and therefore might also be suited for AAA treatment. In this context, this review summarizes the role of different NRs in CVD, mostly atherosclerosis, and discusses in detail the current knowledge of their implications in AAA. From this overview it becomes apparent that NRs that were attributed a beneficial or adverse role in CVD have similar roles in AAA. Together, this overview provides compelling evidence to consider several NRs as attractive targets for future treatment of AAA.

Targetable cellular signaling events mediate vascular pathology in vascular Ehlers-Danlos syndrome

Vascular Ehlers-Danlos syndrome (vEDS) is an autosomal-dominant connective tissue disorder caused by heterozygous mutations in the COL3A1 gene, which encodes the pro-α 1 chain of collagen III. Loss of structural integrity of the extracellular matrix is believed to drive the signs and symptoms of this condition, including spontaneous arterial dissection and/or rupture, the major cause of mortality. We created 2 mouse models of vEDS that carry heterozygous mutations in Col3a1 that encode glycine substitutions analogous to those found in patients, and we showed that signaling abnormalities in the PLC/IP3/PKC/ERK pathway (phospholipase C/inositol 1,4,5-triphosphate/protein kinase C/extracellular signal-regulated kinase) are major mediators of vascular pathology. Treatment with pharmacologic inhibitors of ERK1/2 or PKCβ prevented death due to spontaneous aortic rupture. Additionally, we found that pregnancy- and puberty-associated accentuation of vascular risk, also seen in vEDS patients, was rescued by attenuation of oxytocin and androgen signaling, respectively. Taken together, our results provide evidence that targetable signaling abnormalities contribute to the pathogenesis of vEDS, highlighting unanticipated therapeutic opportunities.

Acute aortic dissection and pregnancy: Review and meta-analysis of incidence, presentation, and pathologic substrates

OBJECTIVES

Pregnancy has been recognized as a predisposing factor for acute aortic dissection (AAD) although its occurrence is quite rare. Currently, no trial and few prospective studies exist about this catastrophic event. The present review and meta-analysis aims to update information on clinical presentation, potential risk factors, treatment, and outcome of acute dissection during pregnancy and puerperium.

METHODS

A comprehensive search of three databases was performed to identify all patients reported in articles published from January 1987. A proportional single-arm meta-analysis with random-effects model was used to pool these variables: risk factors, pregnancy/postpartum occurrence, surgical characteristics, and outcomes.

RESULTS

A total of 11 reports and 85 patients with pregnancy-related AAD were available for this study. The prevalence of connective tissue disorders was 62%, Marfan syndrome being the most common. Out of 76 patients, 46 (61%) had dissection during pregnancy and 30 (39%) during puerperium; 40% of events occurred in primigravidae and 60% in multigravidae. Type A and type B dissection occurred in 67% vs 33% of patients. Surgery was performed in 73% of cases with a maternal and fetal mortality of 23% and 27%, respectively.

CONCLUSIONS

Throughout pregnancy, AAD is quite rare but fatal, especially in Marfan and Loeys-Dietz syndromes, while isolated bicuspid aortic valve is not a risk factor. Even in Marfan syndrome, pathogenesis and evolution of the disease are still unclear. Occurrence of dissection also during puerperium indicates the need for continuous counselling and aortic size monitoring in women at-risk.

Undernutrition and hyperandrogenism during pregnancy: Role in programming of cardiovascular disease and infertility

Maternal nutritional status programs the development of several systems in female offspring, with effects that depend on the severity, duration, and window of development when the nutritional perturbation is imposed. On the basis of the developmental origins of health and disease concept, we hypothesize that gestational low caloric intake may induce maternal subclinical hyperandrogenism during early pregnancy and compromise cardiovascular health and fertility in the female offspring. To examine this possibility, a literature search for human and animal studies was conducted using two electronic databases, PubMed and Cochrane until April 2019 to address the following questions: (a) Do androgens have a developmental role in cardiovascular and ovarian development? (b) Is excess maternal testosterone linked to cardiovascular disease and infertility? and (c) Could early pregnancy undernutrition enhance maternal androgen production and compromise health and fertility in female offspring? The observations reviewed, establish a potential causative link between maternal undernutrition and subclinical hyperandrogenism with hypertension and reduced ovarian reserve in the progeny. Further studies in appropriate models are needed to better understand whether low energy intake and subclinical maternal hyperandrogenism during early pregnancy can negatively affect the health of the female offspring.

Interleukin-12 and -23 blockade mitigates elastase-induced abdominal aortic aneurysm

Macrophages play an important role in the inflammatory process that contributes to the development of abdominal aortic aneurysm (AAA). Studies of human and mouse AAA tissue reveal expanded populations of macrophages producing an abundance of pro-inflammatory cytokines, including TNF-α, IL-12p40 and high level of metalloprotease 9 (MMP-9) at the late stages of disease. Herein, we show that blockade of IL-12p40 in the early phase of aneurysm development suppresses macrophage expansion, inflammatory cytokine and MMP-9 production and mitigates AAA development. Since IL-12 and IL-23 are related cytokines that share the common p40 subunit, we also evaluate the effect of direct IL-23 blockade on the development of AAA. Specific IL-23p19 blockade prevents AAA progression with the same efficiency as IL-12p40 antagonism, suggesting that the efficacy of anti-IL-12p40 treatment may reflect IL-23 blockade. IL-12p40 and IL-23p19 are also abundantly expressed in human AAA tissue. Our findings have potential translational value since IL-12p40 and IL-23p19 antagonists already exist as FDA-approved therapeutics for various chronic inflammatory conditions.

Androgen receptor deficiency in monocytes/macrophages does not alter adiposity or glucose homeostasis in male mice

Androgen deprivation in men leads to increased adiposity, but the mechanisms underlying androgen regulation of fat mass have not been fully defined. Androgen receptor (AR) is expressed in monocytes/macrophages, which are resident in key metabolic tissues and influence energy metabolism in surrounding cells. Male mice bearing a cell-specific knockout of the AR in monocytes/macrophages (M-ARKO) were generated to determine whether selective loss of androgen signaling in these cells would lead to altered body composition. Wild-type (WT) and M-ARKO mice (12–22 weeks of age, n = 12 per group) were maintained on a regular chow diet for 8 weeks and then switched to a high-fat diet for 8 additional weeks. At baseline and on both the regular chow and high-fat diets, no differences in lean mass or fat mass were observed between groups. Consistent with the absence of differential body weight or adiposity, no differences in food intake (3.0 ± 0.5 g per day for WT mice vs 2.8 ± 0.4 g per day for M-ARKO mice) or total energy expenditure (0.6 ± 0.1 Kcal h⁻¹ for WT mice vs 0.5 ± 0.1 Kcal h⁻¹ for M-ARKO mice) were evident between groups during high-fat feeding. Liver weight was greater in M-ARKO than that in WT mice (1.5 ± 0.1 g vs 1.3 ± 0.0 g, respectively, P = 0.02). Finally, M-ARKO mice did not exhibit impairments in glucose tolerance or insulin sensitivity relative to WT mice at any study time point. In aggregate, these findings suggest that AR signaling specifically in monocytes/macrophages does not contribute to the regulation of systemic energy balance, adiposity, or insulin sensitivity in male mice.

Testosterone inhibits aneurysm formation and vascular inflammation in male mice

Abdominal aortic aneurysm (AAA), one of the pathological phenotypes of vascular aging, is characterized by aortic dilation with impaired arterial wall integrity. Recent epidemiologic studies have shown that men with AAA have lower serum testosterone compared to men without. However, the underlying mechanisms remain unclear. In this study, we investigated the effects of testosterone on AAA formation using a murine AAA model under the conditions of depletion and administration of testosterone. In wild-type male mice (C57BL/6J), AAA was induced by CaCl2 application and angiotensin II infusion at 5 weeks after castration. Exacerbated AAA formation was seen in castrated mice, compared with sham-operated mice. Histological analysis revealed marked infiltration of macrophages in the destroyed aorta and IL-6/pSTAT3 expression was significantly elevated, suggesting that AAA development by castration is attributable to pronounced inflammation. Conversely, both 4-week and 9-week administration of testosterone significantly prevented AAA formation, and improvement of histological findings was confirmed. Aortic F4/80, Il-1b and Il-6 expression were significantly inhibited both by testosterone administration. Indeed, mice with implanted flutamide exhibited exacerbated AAA formation and aortic F4/80, Il-1b and Il-6 expression were significantly increased. Taken together, these results demonstrate that testosterone depletion and AR blockade precede AAA formation, and conversely, testosterone administration could suppress AAA formation by regulating macrophage-mediated inflammatory responses. This anti-inflammatory action of testosterone/AR on AAA formation might provide a mechanistic insight into the vascular protective actions of testosterone and suggest that its proper administration or selective AR modulators might be novel therapeutic strategies for this aortic pathology.

Loss of the androgen receptor suppresses intrarenal calcium oxalate crystals deposition via altering macrophage recruitment/M2 polarization with change of the miR-185-5p/CSF-1 signals

Crystals can trigger a wide range of kidney injuries that may link to the development of kidney stones. Infiltrating macrophages may influence hyperoxaluria-induced intrarenal calcium oxalate (CaOx) crystals deposition, yet their linkage to sex hormones remains unclear. Here we demonstrated that suppressing the androgen receptor (AR) expression in renal tubular epithelial cells increased the macrophage recruitment/M2 polarization that may result in enhancing the phagocytosis of intrarenal CaOx crystals. Mechanism dissection suggested that AR can suppress macrophage colony-stimulating factor 1 (CSF-1) expression via increasing miRNA-185-5p expression to suppress the M2 macrophage polarization-mediated intrarenal CaOx crystals phagocytosis. The preclinical study using glyoxylate-induced intrarenal CaOx crystals deposition mouse model revealed that renal tubule-specific AR knockout mice have less intrarenal CaOx crystals deposition with more recruited M2 macrophages in the kidney compared with the wild-type mice. Results from the in vivo rat model using hydroxy-L-proline-induced CaOx crystals deposition also demonstrated that targeting the AR with ASC-J9® suppressed the intrarenal CaOx crystals deposition via increasing the renal macrophage recruitment/M2 polarization. Together, results from multiple preclinical studies using multiple in vitro cell lines and in vivo mouse/rat models all demonstrated that targeting the AR with a small molecule ASC-J9® may function via altering macrophage recruitment/M2 polarization to decrease the intrarenal CaOx crystals deposition, a key phenotype seen in many kidney stone disease patients with hyperoxaluria.

Suppressed androgen receptor expression promotes M2 macrophage reprogramming through the STAT3/SOCS3 pathway

Macrophages are important mediators of inflammatory cardiovascular diseases, and various macrophage phenotypes exert opposite effects during inflammation. In our previous study, we proved that suppressed androgen receptor (AR) alleviated inflammation during experimental autoimmune myocarditis (EAM). As anti-inflammatory cells, whether M2 macrophages are involved in this process remains unclear. Here, we showed that anti-inflammatory cytokines and M2 macrophages were elevated when AR was suppressed during EAM. In IL-4 stimulation-induced M2 macrophages, impaired AR with ASC-J9 increased the expression of M2 macrophage-related factors. Moreover, suppressed AR expression resulted in macrophage M2 polarization by reducing SOCS3 production and enhancing STAT3 activation. Taken together, our data suggest that AR plays a critical role in macrophage polarization and suppressed redundant AR expression promotes anti-inflammatory M2 macrophages reprogramming. This study suggests a potential therapeutic agent for inflammatory cardiomyopathy through the use of ASC-J9.

Embelin inhibits abdominal aortic aneurysm through decreasing IL‑6‑induced STAT3 and NF‑κB inactivation

The aim of the present study was to investigate the effect of embelin on abdominal aortic aneurysm (AAA). AAA model mice were induced by chronic infusion of 1,000 ng/kg/min Angiotensin II. AAA model mice were treated with 25, 50 or 100 mg/kg embelin for 28 days. Embelin inhibited tumor necrosis factor‑α, interleukin (IL)‑1β, IL‑6, IL‑18 and malondialdehyde (MDA) level activities, increased superoxide dismutase, glutathione (GSH) and GSH peroxidase level activities and inhibited MDA level activities in AAA mice Embelin suppressed the secretion of matrix metalloproteinase‑9 protein expression, monocyte chemoattractant protein‑2 activity and epithelial neutrophil‑activating peptide expression levels in AAA mice. Embelin suppressed phosphorylated‑signal transducer and activator of transcription (STAT) 3, phosphorylated‑p38 mitogen‑activated protein kinase and nuclear factor (NF)‑κB protein expression in AAA mice. These findings indicate that embelin inhibits AAA through decreasing IL‑6‑induced STAT3, and NF‑κB inactivation.

The diagnostic value of microRNA-4787-5p and microRNA-4306 in patients with acute aortic dissection

Acute aortic dissection (AAD) is a life-threatening cardiovascular disease with the high morbidity and mortality. Imaging modalities are the gold standard for the diagnosis of AAD; however, they are not always available in emergency department. Biomarker-assisted diagnosis is important for the early treatment of AAD. The aim of the present study was to identify potential microRNA (miRNA) biomarkers for AAD. Differentially expressed plasma miRNAs between AAD patients and age-matched healthy volunteers were analyzed by miRNA microarray. Quantitative RT-PCR was further performed to verify the expression of selected miRNAs (miR-4787-5p and miR-4306) with an increased number of samples. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic value of miR-4787-5p and miR-4306 as biomarkers for distinguishing AAD. Using TargetScan and miRanda, miR-4787-5p and miR-4306 were selected to predict target gene related to cytokines detecting by dual luciferase assay and western blotting. Nine upregulated and twelve downregulated miRNAs were identified in the circulating plasma of AAD patients. qRT-PCR verified statistically consistent expression of two selected miRNAs with microarray analysis. ROC analyses demonstrated that miR-4787-5p and miR-4306 were specific and sensitive for the early diagnosis of AAD. Bioinformatic predictions and dual luciferase assay suggested that polycystin-1 (PKD1) and transforming growth factor-β1 (TGF-β1) were respectively direct target of miR-4787-5p and miR-4306. Furthermore, the protein expression of the downstream targets of PKD1 and TGF-β1 were significantly reduced following overexpression of miR-4787-5p and miR-4306. These results revealed that miR-4787-5p and miR-4306 could be developed as diagnostic potential biomarkers for AAD, and they could be involved in the pathogenesis of AAD.

Biological and pharmacological evaluation of dimethoxycurcumin: A metabolically stable curcumin analogue with a promising therapeutic potential

Dimethoxycurcumin (DiMC) is a synthetic analog of curcumin with superior inter-related pro-oxidant and anti-cancer activity, and metabolic stability. Numerous studies have shown that DiMC reserves the biologically beneficial features, including anti-inflammatory, anti-carcinogenic, and cytoprotective properties, almost to the same extent as curcumin exhibits. DiMC lacks the phenolic-OH groups as opposed to curcumin, dimethoxycurcumin, and bis-demethoxycurcumin that all vary in the number of methoxy groups per molecule, and has drawn the attentions of researchers who attempted to discover the structure-activity relationship (SAR) of curcumin. In this regard, tetrahydrocurcumin (THC), the reduced and biologically inert metabolite of curcumin, denotes the significance of the conjugated α,β diketone moiety for the curcumin activity. DiMC exerts unique molecular activities compared to curcumin, including induction of androgen receptor (AR) degradation and suppression of the transcription factor activator protein-1 (AP-1). The enhanced AR degradation on DiMC treatment suggests it as a novel anticancer agent against resistant tumors with androgenic etiology. Further, DiMC might be a potential treatment for acne vulgaris. DiMC induces epigenetic alteration more effectively than curcumin, although both showed no direct DNA hypomethylating activity. Given the metabolic stability, nanoparticulation of DiMC is more promising for in vivo effectiveness. However, studies in this regard are still in its infancy. In the current review, we portray the various molecular and biological functions of DiMC reported so far. Whenever possible, the efficiency is compared with curcumin and the reasons for DiMC being more metabolically stable are elaborated. We also provide future perspective investigations with respect to varying DiMC-nanoparticles.

Differential expression of sex hormone receptors in abdominal aortic aneurysms

OBJECTIVE

Male sex is a significant risk factor for abdominal aortic aneurysm (AAA). Female sex hormones have been reported to prevent aneurysm formation in animal models. The study aims to describe the expression profile of sex hormone receptors in the aneurysm wall of men and women with AAA and compare with unaffected controls.

METHODS

Aneurysm wall biopsies were obtained during elective open repair of AAA in men and women (n=16+16). Aortic vessel wall from controls were obtained at organ donation (n=6). Western blot-, mRNA expression- and immunohistochemical analyses were performed to assess the expression profile of the sex hormone receptors - androgen receptor (AR), progesterone receptor (PR), estrogen receptor α (ERα) and β (ERβ).

RESULTS

The mRNA- and protein expression levels of AR were higher in AAA compared with control aorta (7.26 vs. 5.14, P=0.001). mRNA- and protein expression levels of ERβ were lower in AAA compared with control aorta (9.15 vs. 12.29, P<0.001). mRNA expression levels of PR were higher in AAA compared with control aorta (8.73 vs. 6.21, P=0.003), but could not be confirmed on protein level. The expression profile of sex hormone receptors in men and women with AAA was similar.

CONCLUSION

Expression of sex hormone receptors differs in the aneurysmal aorta compared with unaffected aorta in men and women. A higher expression of AR and a lower expression of ERβ suggest that sex hormone activity could be associated with aneurysm development.

Increased Intimal Hyperplasia After Vascular Injury in Male Androgen Receptor-Deficient Mice

Intimal hyperplasia is a vascular pathological process involved in the pathogenesis of atherosclerosis. Data suggest that T, the most important sex steroid hormone in males, protects men from atherosclerotic cardiovascular disease. T mainly acts via the androgen receptor (AR), and in this study we evaluated formation of intimal hyperplasia in male AR knockout (ARKO) mice using a vascular injury model. Two weeks after ligation of the carotid artery, male ARKO mice showed increased intimal area and intimal thickness compared with controls. After endothelial denudation by an in vivo scraping injury, there was no difference in the reendothelialization in ARKO compared with control mice. Ex vivo, we observed increased outgrowth of vascular smooth muscle cells from ARKO compared with control aortic tissue explants; the number of outgrown cells was almost doubled in ARKO. In vitro, stimulation of human aortic vascular smooth muscle cells with a physiological T concentration inhibited both migration and proliferation of the cells. Analyzing the expression of central regulators of cell proliferation and migration, we found that mRNA and protein levels of p27 were lower in uninjured arteries from ARKO mice and that T replacement to castrated male mice increased p27 mRNA in an AR-dependent manner. In conclusion, AR deficiency in male mice increases intimal hyperplasia in response to vascular injury, potentially related to the effects of androgens/AR to inhibit proliferation and migration of smooth muscle cells.

Daidzein attenuates abdominal aortic aneurysm through NF-κB, p38MAPK and TGF-β1 pathways

The current study focuses on the protection of daidzein on nerves, as daidzein was demonstrated to have a protective effect on neurons of the central nervous system in a glutamate excitotoxicity and oxygen/glucose deprivation model. However, the effect of daidzein on the abdominal aortic aneurysm (AAA) remains unclear. The angiotensin II-induced AAA mouse model was utilized in the present study to determine the effect of daidzein on AAA. The results demonstrated that daidzein significantly attenuated incidence of AAA, max aortic aneurysm and mortality in the angiotensin II‑induced AAA mice. Daidzein had an anti‑inflammatory effect by inhibiting tumor necrosis factor α (TNF-α), interleukin 1β (IL‑1β) and nuclear factor κB (NF‑κB) protein expression. In addition, daidzein strongly suppressed the gene expression of cyclooxygenase (COX)‑2, matrix metalloproteinase 2 (MMP‑2), tissue inhibitor of metalloproteinase 1 (TIMP-1), transforming growth factor β1 (TGF‑β1), and inhibited inducible nitric oxide synthase (iNOS) protein expression in angiotensin II‑induced AAA mice. It also inhibited phosphorylation of the p38 mitogen-activated protein kinase (MAPK) signaling pathway. These results demonstrate, to the best of our knowledge for the first time, that the anti‑inflammatory effects and inhibitory mechanism of daidzein attenuates AAA in angiotensin II‑induced mice. Daidzein contains strong anti‑inflammatory activity and affects various mechanism pathways including the NF‑κB, p38MAPK and TGF-β1 pathway.

Androgen receptor (AR) in cardiovascular diseases

Cardiovascular diseases (CVDs) are still the highest leading cause of death worldwide. Several risk factors have been linked to CVDs, including smoking, diabetes, hyperlipidemia, and gender among others. Sex hormones, especially the androgen and its receptor, androgen receptor (AR), have been linked to many diseases with a clear gender difference. Here, we summarize the effects of androgen/AR on CVDs, including hypertension, stroke, atherosclerosis, abdominal aortic aneurysm (AAA), myocardial hypertrophy, and heart failure, as well as the metabolic syndrome/diabetes and their impacts on CVDs. Androgen/AR signaling exacerbates hypertension, and anti-androgens may suppress hypertension. Androgen/AR signaling plays dual roles in strokes, depending on different kinds of factors; however, generally males have a higher incidence of strokes than females. Androgen and AR differentially modulate atherosclerosis. Androgen deficiency causes elevated lipid accumulation to enhance atherosclerosis; however, targeting AR in selective cells without altering serum androgen levels would suppress atherosclerosis progression. Androgen/AR signaling is crucial in AAA development and progression, and targeting androgen/AR profoundly restricts AAA progression. Men have increased cardiac hypertrophy compared with age-matched women that may be due to androgens. Finally, androgen/AR plays important roles in contributing to obesity and insulin/leptin resistance to increase the metabolic syndrome.