Androgens, angiogenesis and cardiovascular regeneration

Endometriosis-Associated Angiogenesis and Anti-angiogenic Therapy for Endometriosis

Endometriosis is a known estrogen-dependent inflammatory disease affecting reproductive-aged women. Common symptoms include pelvic pain, dysmenorrhea, dyspareunia, heavy menstrual bleeding, and infertility. The exact etiology of endometriosis is largely unknown, and, thus, the diagnosis and treatment of endometriosis are challenging. A complex interplay of many molecular mechanisms is thought to aid in the progression of endometriosis, most notably angiogenesis. This mini-review examines our current knowledge of the molecular etiology of endometriosis-associated angiogenesis and discusses anti-angiogenic therapy, in the blockade of endometriosis-associated angiogenesis, as potential non-hormonal therapy for the treatment of endometriosis.

Assessment of androgen receptor, IGF-IR and insulin receptor expression in male patients with severe peripheral artery disease

Background

Peripheral artery disease (PAD) of the lower limbs is a common condition that can affect quality of life. Androgen receptor (AR) can exert sex-specific effects on metabolic system, endothelial function and vascular tone. IGF-I receptor (IGF-IR) and insulin receptor (IR) may also be involved in the aforementioned functions. The aim of this study was to evaluate AR, IGF-IR and IR expression in the arterial vessel walls of PAD patients.

Results

This is a cross-sectional study examining 30 males with PAD undergoing open surgery procedures. Mean age was 75.9 ± 8.8y. All patients belonged to Rutherford stage 4–6. Median expression levels of IR, IGF-IR and AR significantly decreased from stage 4–6 (p < 0.05).

Significance

The study evidenced a progressive decrease of IR, IGF-IR and AR expression as the severity of disease increased. Altered levels of IR, IGF-IR and AR following PAD may be useful for the clinical evaluation of these patients.

Involvement of Testosterone Signaling in the Integrity of the Neurovascular Unit in the Male: Review of Evidence, Contradictions, and Hypothesis

Age-related central nervous system function decline and increased susceptibility of females compared to males with respect to prevalence of several neurodegenerative and neuropsychiatric diseases are both based on the principle that hormonal factors could be involved. These cerebral disorders are characterized by an alteration of blood-brain barrier (BBB) properties and chronic neuroinflammation, which lead to disease progression. Neuroinflammation, in turn, contributes to BBB dysfunction. The BBB and its environment, called the neurovascular unit (NVU), are crucial for cerebral homeostasis and neuronal function. Interestingly, sex steroids influence BBB properties and modulate neuroinflammatory responses. To date however, the majority of work reported has focused on the effects of estrogens on BBB function and neuroinflammation in female mammals. In contrast, the effects of testosterone signaling on the NVU in males are still poorly studied. The aim of this review was to summarize and discuss the literature, providing insights and contradictions to highlight hypothesis and the need for further investigations.

Evaluation the effect of testosterone on the number of endothelial progenitor cells and amount of SDF-1α, PDGF, bFGF, and NO

Background:

Recent therapeutic advances in cardiovascular disease, thanks to the discovery of endothelial progenitor cells (EPCs). Stromal cell-derived factor-1α (SDF-1α), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF), and nitric oxide (NO) play a role in migration, homing, and differentiation of EPCs into mature endothelial cells. The incidence of cardiovascular disease is higher in men than in women. This fact suggests the influence of sex hormones on incidence of cardiovascular disease.

Methods:

Twenty-four female wistar rats weighing 160–180 g were randomly divided into four groups (N = 6): 1. sham-treated by sesame oil, 2. ovariectomized (OVX)-treated by sesame oil, 3. OVX-treated by 10 μg/kg/day testosterone, and 4. OVX-treated by 100 μg/kg/day testosterone. After 21 days, the animals were euthanized and blood samples were saved for determination of EPC count and serum levels of SDF-1α, PDGF, bFGF, and NO production.

Results:

High-dose testosterone induced significant increase in EPC count in OVX rats (P < 0.05). Also 100 μg/kg/day testosterone increased serum level of SDF-1α more than OVX-treated by 10 μg/kg/day testosterone (P < 0.05). But 10 μg/kg/day testosterone increased significantly the serum level of PDGF >100 μg/kg/day testosterone-treated group (P < 0.05). The serum level of bFGF in sham-treated by sesame oil was equal with its concentration in OVX-treated by 100 μg/kg/day testosterone. And the serum concentration of NO production in testosterone-treated groups were significantly less than other groups (P < 0.05).

Conclusions:

This study suggests that testosterone might be effective on cardiovascular disease in females by increasing EPC count through SDF-1α and PDGF mechanisms which are some of the vascular healing factors.

Role of androgens for urethral homeostasis

Background

We observed that patients with hypogonadism are at higher risk to experience artificial urinary sphincter cuff erosion. Sphincter erosions have been found to be associated with urethral atrophy or compromised urethras subsequent to events limiting its blood supply. We therefore analyzed possible mechanisms how a decrease in testosterone serum levels can result decreased urethral blood flow.

Methods

In a cohort of >1,200 urethroplasties, tissue specimens obtained during surgeries were analyzed for expression of androgen receptor (AR), AR-responsive TIE-2 associated with angiogenesis, and the endothelial cell marker CD31 for determination of vessel counts were analyzed immunohistochemically. A total of 11 patients were included in whom both tissue and serum testosterone levels within 2 years of the urethroplasty was available. Low serum testosterone level defined as <280 ng/dL. Image J software was used to analyze expression profiles.

Results

Mean serum testosterone level was significant lower in hypogonadal patients (179.4 ng/dL) compared to eugonadal patients (375.0 ng/dL, P=0.003). Urethral tissue of hypogonadal patients showed decreased AR expression [1.11% high power field (HPF)] compared to eugonadal patients (1.62%, P=0.016), decreased TIE-2 expression (1.84% HPF vs. 3.08%, P=0.006), and also decreased vessel counts (44.47 vessels/HPF vs. 98.33, P=0.004). There was a direct correlation of AR and TIE-2 expression levels with serum testosterone levels (rho 0.685, P=0.029, and rho 0.773, P=0.005, respectively). Of note, we did not detect a difference in age, prior radiation, coronary artery disease or hypertension among hypo- or eugonadal patient. However, higher body mass index was associated with low serum testosterone levels.

Conclusions

Hypogonadal status is associated with decreased expression of AR and TIE-2 and also reduced vessel count in urethral tissue. We believe that the resulting decreased urethral vascularity subsequent to a hypogonadal state may be an important risk factor for complications of urethral surgery.

Internal Jugular Vein Cross-Sectional Area and Cerebrospinal Fluid Pulsatility in the Aqueduct of Sylvius: A Comparative Study between Healthy Subjects and Multiple Sclerosis Patients

Objectives

Constricted cerebral venous outflow has been linked with increased cerebrospinal fluid (CSF) pulsatility in the aqueduct of Sylvius in multiple sclerosis (MS) patients and healthy individuals. This study investigates the relationship between CSF pulsatility and internal jugular vein (IJV) cross-sectional area (CSA) in these two groups, something previously unknown.

Methods

65 relapsing-remitting MS patients (50.8% female; mean age = 43.8 years) and 74 healthy controls (HCs) (54.1% female; mean age = 43.9 years) were investigated. CSF flow quantification was performed on cine phase-contrast MRI, while IJV-CSA was calculated using magnetic resonance venography. Statistical analysis involved correlation, and partial least squares correlation analysis (PLSCA).

Results

PLSCA revealed a significant difference (p<0.001; effect size = 1.072) between MS patients and HCs in the positive relationship between CSF pulsatility and IJV-CSA at C5-T1, something not detected at C2-C4. Controlling for age and cardiovascular risk factors, statistical trends were identified in HCs between: increased net positive CSF flow (NPF) and increased IJV-CSA at C5-C6 (left: r = 0.374, p = 0.016; right: r = 0.364, p = 0.019) and C4 (left: r = 0.361, p = 0.020); and increased net negative CSF flow and increased left IJV-CSA at C5-C6 (r = -0.348, p = 0.026) and C4 (r = -0.324, p = 0.039), whereas in MS patients a trend was only identified between increased NPF and increased left IJV-CSA at C5-C6 (r = 0.351, p = 0.021). Overall, correlations were weaker in MS patients (p = 0.015).

Conclusions

In healthy adults, increased CSF pulsatility is associated with increased IJV-CSA in the lower cervix (independent of age and cardiovascular risk factors), suggesting a biomechanical link between the two. This relationship is altered in MS patients.

Internal Jugular Vein Cross-Sectional Area Enlargement Is Associated with Aging in Healthy Individuals

Background

Internal jugular vein (IJV) narrowing has been implicated in central nervous system pathologies, however normal physiological age- and gender-related IJV variance in healthy individuals (HIs) has not been adequately assessed.

Objectives

We assessed the relationship between IJV cross-sectional area (CSA) and aging.

Materials and Methods

This study involved 193 HIs (63 males and 130 females) who received 2-dimensional magnetic resonance venography at 3T. The minimum CSA of the IJVs at cervical levels C2/C3, C4, C5/C6, and C7/T1 was obtained using a semi-automated contouring-thresholding technique. Subjects were grouped by decade. Pearson and partial correlation (controlled for cardiovascular risk factors, including hypertension, heart disease, smoking and body mass index) and analysis of variance analyses were used, with paired t-tests comparing side differences.

Results

Mean right IJV CSA ranges were: in males, 41.6 mm² (C2/C3) to 82.0 mm² (C7/T1); in females, 38.0 mm² (C2/C3) to 62.3 mm² (C7/T1), while the equivalent left side ranges were: in males, 28.0 mm² (C2/C3) to 52.2 mm² (C7/T1); in females, 27.2 mm² (C2/C3) to 47.8 mm² (C7/T1). The CSA of the right IJVs was significantly larger (p<0.001) than the left at all cervical levels. Controlling for cardiovascular risk factors, the correlation between age and IJV CSA was more robust in males than in the females for all cervical levels.

Conclusions

In HIs age, gender, hand side and cervical location all affect IJV CSA. These findings suggest that any definition of IJV stenosis needs to account for these factors.

Cardiovascular risk with androgen deprivation therapy for prostate cancer: potential mechanisms

Androgen deprivation therapy (ADT) is frequently used for the treatment of advanced prostate cancer. ADT is associated with numerous side effects related to its mode of action, namely the suppression of testosterone to castrate levels. Recently, several large retrospective studies have also reported an increased risk of diabetes and cardiovascular disease in men receiving ADT, although these risks have not been confirmed by prospective randomized trials. We review the literature to consider the risk of cardiovascular disease with different forms of ADT and examine in detail potential mechanisms by which any such risk could be mediated. Mechanisms discussed include the metabolic syndrome resulting from low testosterone level and the potential roles of testosterone flare, gonadotropin-releasing hormone receptors outside the pituitary gland, and altered levels of follicle-stimulating hormone. Finally, the clinical implications for men prescribed ADT for the treatment of advanced prostate cancer are considered.

Androgen receptor in human endothelial cells

Androgen receptor (AR) is a ligand-inducible transcription factor, and a member of the steroid-thyroid-retinoid receptor superfamily, that mediates the biological effects of androgens in a wide range of physiological and pathological processes. AR expression was identified in vascular cells nearly 20 years ago, and recent research has shown that AR mediates a variety of actions of androgens in endothelial and vascular smooth muscle cells. In this mini-review, we review evidence indicating the importance of AR in human endothelial cell (HUVEC) homeostatic and pathogenic processes. Although a role for AR in the modulation of HUVEC biology is evident, the molecular mechanisms by which AR regulates HUVEC homeostasis and disease processes are not fully understood. Understanding these mechanisms could provide critical insights into the processes of pathogenesis of diseases ranging from cardiovascular disease to cancer that are major causes of human morbidity and mortality.

Aging impairs VEGF-mediated, androgen-dependent regulation of angiogenesis

There is a progressive impairment of vascular repair mechanisms with advancing age concomitant with a steady decline in circulating androgen levels in men. Emerging evidence indicates androgens regulate angiogenesis; however, little research has focused on the impact of age upon androgen-mediated regulation of angiogenic mechanisms. Human dermal fibroblasts from young (<30 years) and older (>65 years) men were incubated with DHT, with or without androgen receptor antagonist hydroxyflutamide, or phosphoinositide 3-kinase inhibitor. Fibroblast-conditioned medium was used to stimulate angiogenic functions in human umbilical vein endothelial cells. Nuclear fractionation and fluorescence microscopy were used to study androgen receptor (AR) distribution. Conditioned medium from fibroblasts of young men, but not old men, treated with DHT produced a 3-fold increase in human umbilical vein endothelial cell tubulogenesis and 2-fold increase in migration via increased vascular endothelial growth factor (VEGF) expression and secretion, predominantly of VEGF145. DHT-induced VEGF secretion from fibroblasts of young men was AR-dependent and increased AKT phosphorylation, which was abrogated by phosphoinositide 3-kinase inhibition. By contrast, fibroblasts from older men were unresponsive to DHT and lacked androgen-mediated enhancement in VEGF production. These findings were associated with reduced AR nuclear translocation in old fibroblasts. The failure of DHT-induced paracrine stimulation of angiogenesis in fibroblasts from older men is likely due to defective nuclear translocation of AR. This first demonstration of androgen resistance (or insensitivity) acquired by human fibroblasts with aging suggests that pharmacological testosterone therapy for old men may be less effective in enhancing angiogenesis and facilitating tissue regeneration mechanisms reliant on paracrine release of VEGF.

Regeneration of breeding tubercles on zebrafish pectoral fins requires androgens and two waves of revascularization

Sexually dimorphic breeding tubercles (BTs) are keratinized epidermal structures that form clusters on the dorsal surface of the anterior rays of zebrafish male pectoral fins. BTs appear during sexual maturation and are maintained through regular shedding and renewal of the keratinized surface. Following pectoral fin amputation, BT clusters regenerate after the initiation of revascularization, but concomitantly with a second wave of angiogenesis. This second wave of regeneration forms a web-like blood vessel network that penetrates the supportive epidermis of BTs. Upon analyzing the effects of sex steroids and their inhibitors, we show that androgens induce and estrogens inhibit BT cluster formation in intact and regenerating pectoral fins. Androgen-induced BT formation in females is accompanied by the formation of a male-like blood vessel network. Treatment of females with both androgens and an angiogenesis inhibitor results in the formation of undersized BT clusters when compared with females treated with androgens alone. Overall, the growth and regeneration of large BTs requires a hormonal stimulus and the presence of an additional blood vessel network that is naturally found in males.

High serum testosterone is associated with reduced risk of cardiovascular events in elderly men. The MrOS (Osteoporotic Fractures in Men) study in Sweden

OBJECTIVES

We tested the hypothesis that serum total testosterone and sex hormone-binding globulin (SHBG) levels predict cardiovascular (CV) events in community-dwelling elderly men.

BACKGROUND

Low serum testosterone is associated with increased adiposity, an adverse metabolic risk profile, and atherosclerosis. However, few prospective studies have demonstrated a protective link between endogenous testosterone and CV events. Polymorphisms in the SHBG gene are associated with risk of type 2 diabetes, but few studies have addressed SHBG as a predictor of CV events.

METHODS

We used gas chromatography/mass spectrometry to analyze baseline levels of testosterone in the prospective population-based MrOS (Osteoporotic Fractures in Men) Sweden study (2,416 men, age 69 to 81 years). SHBG was measured by immunoradiometric assay. CV clinical outcomes were obtained from central Swedish registers.

RESULTS

During a median 5-year follow-up, 485 CV events occurred. Both total testosterone and SHBG levels were inversely associated with the risk of CV events (trend over quartiles: p = 0.009 and p = 0.012, respectively). Men in the highest quartile of testosterone (≥550 ng/dl) had a lower risk of CV events compared with men in the 3 lower quartiles (hazard ratio: 0.70, 95% confidence interval: 0.56 to 0.88). This association remained after adjustment for traditional CV risk factors and was not materially changed in analyses excluding men with known CV disease at baseline (hazard ratio: 0.71, 95% confidence interval: 0.53 to 0.95). In models that included both testosterone and SHBG, testosterone but not SHBG predicted CV risk.

CONCLUSIONS

High serum testosterone predicted a reduced 5-year risk of CV events in elderly men.

Intracavernous administration of bone marrow mononuclear cells: a new method of treating erectile dysfunction?

While PDE5 inhibitors have revolutionized treatment of ED, approximately 30% of patients are non-responsive. A significant cause of this is vascular and smooth muscle dysfunction, as well as nerve atrophy. Autologous administration of bone marrow mononuclear cells (BMMC) has been performed in over 2000 cardiac patients without adverse effects, for stimulation of angiogenesis/regeneration. Despite its ease of access, and dependence on effective vasculature for function, comparatively little has been perform in terms of BMMC therapy for ED. Here we outline the rationale for use of autologous BMMC in patients with ED, as well as provide early safety data on the first use of this procedure clinically.

Effects of androgens on cardiovascular remodeling

Androgens, the male sex hormones, exert various biological effects on many target organs through the transcriptional effects of the nuclear androgen receptor (AR). ARs are expressed not only in classical target organs, such as the brain, genital organs, bone, and skeletal muscles, but also in the cardiovascular system. Because the female sex hormones estrogens are well-known to protect against cardiovascular disease, sex has been considered to have a significant clinical impact on cardiovascular mortality. However, the influence of androgens on the cardiovascular system has not been fully elucidated. To clarify this issue, we analyzed the effects of administration of angiotensin II and doxorubicin, an anticancer agent, in a loading model in male wild-type and AR-deficient mice. In this review, we focus on the actions of androgens as potential targets for the prevention of cardiovascular diseases in males.

Effects of aging on angiogenesis

Aging is a dominant risk factor for most forms of cardiovascular disease. Impaired angiogenesis and endothelial dysfunction likely contribute to the increased prevalence of both cardiovascular diseases and their adverse sequelae in the elderly. Angiogenesis is both an essential adaptive response to physiological stress and an endogenous repair mechanism after ischemic injury. In addition, induction of angiogenesis is a promising therapeutic approach for ischemic diseases. For these reasons, understanding the basis of age-related impairment of angiogenesis and endothelial function has important implications for understanding and managing cardiovascular disease. In this review, we discuss the molecular mechanisms that contribute to impaired angiogenesis in the elderly and potential therapeutic approaches to improving vascular function and angiogenesis in aging patients.

Angiogenesis is a link between atherosclerosis and tumorigenesis: role of LOX-1

Angiogenesis is defined as the formation of new blood vessels sprouting from pre-existing vessels. It plays an important role not only in physiological situations such as embryonic vascular development and wound healing, but also in pathological conditions including atherogenesis and evolution and spread of certain tumors. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), a receptor for oxidized low density lipoprotein (ox-LDL), is mainly expressed in endothelial cells. It has diverse physiological functions and it could be a link between atherogenesis and tumorigenesis. The risk factors for atherosclerosis like hypertension, diabetes mellitus and hyperlipidemia are associated with LOX-1. Dyslipidemia and obesity are also being recognized as risk factor for certain tumors. LOX-1 is also found to be important for maintaining the transformed state in developmentally diverse cancer cell lines and for tumor growth. There is emerging evidence that LOX-1 plays an important role in the angiogenesis process. In this review, we outline the roles of angiogenesis in atherogenesis and tumorigenesis, and describe the role of LOX-1 as a potential molecular target for blocking angiogenesis.

Gender-specific differences in the urinary expression of aldosterone, IL-1α and IL-1β

Aims: This pilot investigation examined the possibility of using urine specimens to explore the difference between the expression of several biomarkers based on gender. These biomarkers include several associated with cardiac damage, oxidative stress and inflammation. Materials & methods: Urine specimens were assayed for total protein, aldosterone, high-sensitivity C-reactive protein, myeloperoxidase and IL-1α and -1β using ELISA. Results: We observed significant differences between the sexes for aldosterone and IL-1α and -1β. Conclusion: The presence of gender-based differences in the urinary expression of these biomarkers may be important for establishing normal baseline values in males and females, and may prove to be of value in the development of rapid noninvasive ways to assess inflammatory and oxidative injury during routine urinalysis.