Endothelial function in patients with metabolic syndrome and erectile dysfunction: a question of Angiopoietin imbalance?

ROUX-en-Y gastric bypass surgery improves metabolic syndrome-related erectile dysfunction in mice via the IRS-1/PI3K/AKT/eNOS pathway

Objective

Although many clinical studies have shown that ROUX-en-Y gastric bypass (RYGB) surgery significantly improves metabolic syndrome-related erectile dysfunction (MED), the role and mechanism are unclear.

Aim

In this study we used a mouse model to explore how RYGB improves MED induced by a high-fat diet (HFD).

Methods

We established a mouse model of metabolic syndrome by feeding an HFD for 16 weeks. The mice were randomly assigned to the standard chow diet (SCD), HFD, or RYGB groups. Body weight, fasting blood glucose, plasma insulin, and total plasma cholesterol were analyzed. Erectile responses were evaluated by determining the mean systolic blood pressure and the intracavernosal pressure (ICP). Penile histologic examination (Masson's trichrome and immunohistochemical stain) and Western blot were performed.

Result

Compared with the SCD group, the ICP in the sham group was significantly lower, and the ICP of the RYGB was significantly increased. Masson's trichrome and immunohistochemical staining showed that the content of endothelium and smooth muscle in the corpus cavernosum of mice with MED was significantly reduced. Western blot analysis showed a significant decrease in α-smooth muscle actin and a significant increase in osteopontin in penile tissue in the sham group, which was improved by RYGB surgery. Furthermore, RYGB significantly increased IRS-1/PI3K/Akt/eNOS phosphorylation.

Clinical Translation

In this study we explored the mechanism of bariatric surgery to improve erectile dysfunction associated with metabolic syndrome and provided a theoretical basis for clinical research.

Strengths and Limitations

First, we did not investigate the mechanism by which RYGB affects the IRS-1/PI3K/Akt/eNOS signaling pathway. Second, the effect of the IRS-1/PI3K/Akt/eNOS signaling pathway on the function of corpus cavernosum endothelial cells and smooth muscle cells remains to be investigated in cellular studies.

Conclusion

This study demonstrated that RYGB may not only improve metabolic parameters but also restore erectile function in MED patients. The mechanism of the therapeutic effect of RYGB may be reactivation of the IRS-1/PI3K/Akt/eNOS pathway.

Altered brain activity in diabetic patients with erectile dysfunction revealed by fractional amplitude of low-frequency fluctuation: A resting-state fMRI study

INTRODUCTION

Diabetes mellitus is one of the major chronic diseases, which enhances the risk of erectile dysfunction. However, the central pathological mechanisms of erectile dysfunction in diabetes mellitus patients are still unclear.

METHODS

Resting-state functional magnetic resonance imaging data were acquired in 30 type-2 diabetes mellitus, 31 type-2 diabetes mellitus with erectile dysfunction patients, and 31 healthy controls. The measure of fractional amplitude of low-frequency fluctuation was calculated and compared among groups.

RESULTS

Differences of fractional amplitude of low-frequency fluctuation values were found in the left superior frontal gyrus (medial) and middle temporal gyrus among three groups. Compared with healthy controls group, type-2 diabetes mellitus group exhibited lower fractional amplitude of low-frequency fluctuation values in the left superior frontal gyrus (dorsolateral), anterior cingulate gyrus, calcarine fissure, and increased fractional amplitude of low-frequency fluctuation values in the left post-central gyrus. Compared with healthy controls group, erectile dysfunction with type-2 diabetes mellitus group exhibited lower fractional amplitude of low-frequency fluctuation values in the left superior frontal gyrus (medial), middle temporal gyrus, temporal middle (pole), and increased fractional amplitude of low-frequency fluctuation values in the right post-central gyrus. Compared with type-2 diabetes mellitus group, erectile dysfunction with type-2 diabetes mellitus group exhibited increased fractional amplitude of low-frequency fluctuation values in the right median cingulum gyrus and left calcarine fissure.

CONCLUSION

Erectile dysfunction with type-2 diabetes mellitus patients showed functional changes in brain regions that were closely correlated with sexual dysfunction, which suggested that altered regional brain activity might be related to the pathophysiology of erectile dysfunction with type-2 diabetes mellitus.

Chronic liver diseases and erectile dysfunction

Chronic liver diseases (CLDs) are characterized by progressive necrosis of hepatocytes, which leads to liver fibrosis and cirrhosis, and ultimately liver dysfunction. The statistics of 2020 shows that the number of patients with CLDs, including chronic hepatitis, fatty liver, and cirrhosis, may exceed 447 million in China. The liver is a crucial organ for the metabolism of various substances, including sex hormones and lipids. CLDs frequently result in abnormalities in the metabolism of sex hormones, glucose, and lipids, as well as mental and psychological illnesses, all of which are significant risk factors for erectile dysfunction (ED). It has been reported that the prevalence of ED in male patients with CLDs ranges from 24.6 to 85.0%. According to a survey of Caucasians, liver transplantation may improve the erectile function of CLDs patients with ED. This finding supports the link between CLDs and ED. In addition, ED is often a precursor to a variety of chronic diseases. Given this correlation and the significant prevalence of CLDs, it is important to evaluate the epidemiology, risk factors, etiology, and treatment outcomes of ED in male patients with CLDs, expecting to attract widespread attention.

The influence of metabolic profile of obese men on the severity of erectile dysfunction: are metabolically healthy obese individuals protected?

OBJECTIVE

To determine the prevalence of erectile dysfunction (ED) in metabolically healthy obese (MHO) individuals, and to compare ED severity and hypogonadism prevalence in MHO, metabolically unhealthy obese (MUO) and metabolically healthy non-obese individuals.

MATERIAL AND METHODS

ED patients (n=460) were evaluated by standardized protocol, that included clinical evaluation, abridged 5-item version of the International Index of Erectile Function (IIEF-5) questionnaire survey, and Penile Duplex Doppler Ultrasound (PDDU) exam. Patients were classified as obese [body mass index (BMI) ≥30.0 kg/m²] and non-obese (BMI <30.0 kg/m²), and metabolic health status was defined by National Cholesterol Education Program Adult Treatment Panel III (NCEP ATPIII) criteria. Statistical analysis was performed and statistical significance was considered at p-level <0.05.

RESULTS

The mean age of the subjects was 56.2±10.5 years. MHO was present in 40% of obese individuals (n=37). MUO had lower mean peak systolic velocity (mPSV) compared to MHO (28.1 cm/s vs. 36.9 cm/s; p=0.005), and IIEF-5 scores were also lower in MUO compared to MHO patients (10.2 vs. 13.1; p=0.018). No statistical differences in IIEF-5 score, mPSV and hypogonadism prevalence between MHO and metabolically healthy non-obese (MHNO) patients were observed.

CONCLUSION

Our results lead us to conclude that healthy metabolic profile protects obese individuals from severity of ED. The strong association between obesity and ED may be otherwise attributed to metabolic abnormalities present in the obese.

Serum Biomarkers of Erectile Dysfunction in Diabetes Mellitus: A Systematic Review of Current Literature

INTRODUCTION

Erectile dysfunction (ED) is a common complication in patients with diabetes mellitus (DM). However, the utility of serum biomarkers as clinical surrogates for the development and/or progression of ED is unknown.

AIM

To summarize the current literature for serum biomarkers for ED in DM and emphasize areas for future research.

MAIN OUTCOME MEASURES

Human subject data demonstrating the utility of serum markers for the development and progression of ED in patients with DM.

METHODS

We performed a systematic PubMed-Medline search in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement using Medical Subject Headings (MeSH) for articles published from January 1, 2000 through December 31, 2016 of serum biomarkers for development or progression of ED in patients with DM using erectile dysfunction [MeSH] AND (biomarkers [MeSH] or inflammation mediators [MeSH] or intercellular signaling peptides and proteins [MeSH] or cell adhesion molecules [MeSH]). A thorough review of these studies was completed.

RESULTS

Of the 327 abstracts screened, 12 full-text studies were assessed and 1 study was excluded. Eleven studies assessing serum biomarkers for ED in patients with DM were included in this review. The most studied serum biomarkers for ED in men with DM included endothelial dysfunction markers such as serum E-selectin, endothelial progenitor cells, and endothelial microparticles and specific markers of inflammation such as interleukin-10, ratio of tumor necrosis factor-α to interleukin-10, and reactive oxygen species such as nitric oxide and malondialdehyde. Reliable serum biomarkers will enable earlier diagnosis and objective monitoring of disease progression and responses to treatment in patients with ED.

CONCLUSION

Serum biomarkers for ED in men with DM are very limited. Future longitudinal studies with uniform patient characteristics are needed to evaluate the potential clinical use of serum biomarkers in men with DM for the development and progression of ED. Patel DP, Craig JR, Myers JB, et al. Serum Biomarkers of Erectile Dysfunction in Diabetes Mellitus: A Systematic Review of Current Literature. Sex Med Rev 2017:5:339-348.

Angiopoietin-2, its soluble receptor Tie-2, and metabolic syndrome components in a population-based sample

OBJECTIVE

Since angiopoietin-2 (Ang-2) levels strongly correlate with cardiovascular mortality and subclinical cardiovascular disease, it was hypothesized that levels of Ang-2 and its soluble receptor (sTie-2) were associated with the metabolic syndrome (MetS) and individual MetS components.

METHODS

Within the population-based Study of Health in Pomerania, two sets of analyses were performed. First, Ang-2 and sTie-2 were related to the prevalence of MetS and its components cross-sectionally (n = 3,205). Second, the association between baseline Ang-2 and sTie-2 and incident MetS or longitudinal changes in its components in 1,295 individuals was investigated.

RESULTS

High Ang-2 levels (90th percentile), compared with low Ang-2 levels (10th percentile), were positively associated with MetS (OR: 1.78) and with the following MetS criteria: increased triglycerides, lower HDL cholesterol, and higher non-fasting glucose. Furthermore, high sTie-2 levels (90th percentile), compared with low levels (10th percentile), were positively related to MetS (OR: 1.58) and most of its components. However, Ang-2 and sTie-2 levels were not associated with incident MetS or longitudinal change in components of MetS.

CONCLUSIONS

Ang-2 and sTie-2 levels were cross-sectionally associated with MetS and several of its components. However, Ang-2 and sTie-2 levels were not associated with incident MetS or changes in individual MetS components during follow-up.

Association of erectile dysfunction with depression in patients with chronic viral hepatitis

AIM: To investigate the prevalence of erectile dysfunction (ED) and its association with depression in patients with chronic viral hepatitis.

METHODS: This single center cross-sectional study was conducted from August 2013 through January 2014. All outpatients with chronic viral hepatitis in our liver clinic between 18 and 80 years of age were considered eligible for this study. The exclusion criteria included well-established causes of ED, such as diabetes, hypertension, hyperlipidemia, alcohol abuse, liver cirrhosis, ischemic heart disease, renal disease, neurologic disease, and malignancy. We also excluded the patients who had incompletely answered the questionnaires. ED was assessed using the validated Korean version of the International Index of Erectile Function (IIEF-5) scale. The Korean version of the self-administered Beck Depression Inventory (BDI) scale was used to assess depression in the patients. Demographic and medical data were obtained from the patients’ medical records. Current or past history of psychiatric diagnosis and drug history including the use of an antiviral agent and an antidepressant were also recorded.

RESULTS: A total of 727 patients met the initial eligibility criteria. Six hundred seventeen patients were excluded because their medical records contained one or more of the previously determined exclusion criteria. The remaining 110 patients were assessed based on the BDI and IIEF-5 questionnaires. Based on the IIEF-5 scale, the prevalence of ED among patients with chronic viral hepatitis was 40%. Compared with the non-ED group, patients in the ED group were older. The proportion of patients in the ED group who had a job or who were naïve peg-interferon users was lower than that in patients in the non-ED group. Patients with ED had significantly lower scores on the IIEF-5 scale than patients without ED (11.75 ± 4.88 vs 21.33 ± 1.86, P = 0.000). Patients with ED rated significantly higher scores on the BDI scale compared with patients without ED (12.59 ± 7.08 vs 5.30 ± 4.00, P = 0.000). Also, the IIEF-5 scores were negatively correlated with age, employment, and BDI scores. In the multiple logistic regression analysis, age and depression were independently associated with erectile dysfunction (P = 0.019 and 0.000, respectively).

CONCLUSION: Patients with chronic viral hepatitis have a high prevalence of ED. Age and depression are independent factors for ED in male patients with chronic viral hepatitis.

Erectile dysfunction, metabolic syndrome and arterial disease. Clinical-pathological relation by carotid ultrasonography

INTRODUCTION

Different studies have shown the relationship between erectile dysfunction, metabolic syndrome and cardiovascular disease. The objective of this study was to evaluate the presence of arteriopathy performing carotid ultrasound in patients with and without erectile dysfunction.

MATERIAL AND METHODS

We conducted a case-control study with 44 patients consulting for erectile dysfunction and 20 controls. All subjects completed the IIEF-5 test and we studied the criteria for metabolic syndrome, and a carotid ultrasound to study the intima-media thickness and the presence of atherosclerotic plaques was performed.

RESULTS

Mean intima-media thickness was .71mm±.21 for the right and of .71±.17 for the left carotid in patients with erectile dysfunction. In the control group, the means were .54±0.11 and 0.59±0.15mm respectively, statistically significant differences (P=.02 and P=.05 respectively). No plaque was found in any control, but in 25% of both carotid arteries of patients with erectile dysfunction (P=.01). As metabolic syndrome, according to the American Heart Association, were diagnosed 52.8% of patients with erectile dysfunction, and 16.7% of controls, and according to the International Diabetes Federation, 52.3% of patients with erectile dysfunction and 25% of controls met diagnostic criteria. In both cases there were significant differences (P<.01 and P=.02 respectively). We found a positive linear correlation between waist circumference and the intima-media thickness in both carotid (P<.05).

CONCLUSIONS

Patients with erectile dysfunction may be at increased risk of cardiovascular disease, as determined by the presence of arterial disease in the carotid arteries, which indicates that we should made a more thorough and comprehensive study of patients with erectile dysfunction.

Angiopoietin-1 regulates microvascular reactivity and protects the microcirculation during acute endothelial dysfunction: role of eNOS and VE-cadherin

The growth factor angiopoietin-1 (Ang-1) plays an essential role in angiogenesis and vascular homeostasis. Nevertheless, the role of Ang-1 in regulating vascular tone and blood flow is largely unexplored. Endothelial nitric oxide synthase (eNOS) and the junctional protein VE-cadherin are part of the complex signalling cascade initiated by Ang-1 in endothelial cells. In this study, we aimed to investigate the mechanisms underlying acute effects of Ang-1 on microvascular reactivity, permeability and blood flow, and hypothesise that eNOS and VE-cadherin underpin Ang-1 mediated vascular effects that are independent of angiogenesis and proliferation. Myography of isolated microarterioles from male C3H/HeN mice (7-10 weeks) was employed to measure vascular reactivity in vitro. Microcirculatory function in vivo was evaluated by intravital microscopy and Doppler fluximetry in dorsal window chambers. Ang-1 and its stable variant MAT.Ang-1 induced a concentration-dependent vasodilation of arterioles in vitro, which was blocked with nitric oxide (NO) synthesis inhibitor l-NAME. In vivo, MAT.Ang-1 restored to control levels l-NAME induced peripheral vasoconstriction, decreased blood flow and microvascular hyperpermeability. Tissue protein expression of VE-cadherin was reduced by NOS inhibition and restored to control levels by MAT.Ang-1, whilst VE-cadherin phosphorylation was increased by l-NAME and subsequently reduced by MAT.Ang-1 administration. Moreover, MAT.Ang-1 alone did not modulate systemic levels of angiogenetic factors. Our novel findings report that Ang-1 induces arteriolar vasodilation via release of NO, suggesting that Ang-1 is an important regulator of microvascular tone. As MAT.Ang-1 ameliorates detrimental effects on the microcirculation induced by inhibition of NO synthesis and stabilizes the endothelial barrier function through VE-cadherin, we propose that this Ang-1 variant may serve as a novel therapeutic agent to protect the microcirculation against endothelial dysfunction.

Androgens modulate endothelial function and endothelial progenitor cells in erectile physiology

The incidence of erectile dysfunction (ED) increases with age and cardiovascular disease risk factors, such as hypertension, hyperlipidemia, insulin resistance, obesity, and diabetes. These risk factors are thought to contribute to endothelial dysfunction and atherosclerosis, thus contributing to the pathophysiology of ED. The role of the endothelium in regulating erectile physiology is well established. However, the role of androgens in modulating endothelial function and endothelial repair mechanisms subsequent to vascular injury in erectile tissue remains a subject of intensive research. The clinical and preclinical evidence discussed in this review suggests that androgens regulate endothelial function and also play an important role in the development and maturation of endothelial progenitor cells (EPCs), which are thought to play a critical role in repair of endothelial injury in vascular beds. In this review, we discuss the data available on the effects of androgens on endothelial function and EPCs in the repair of vascular injury. Indeed, more research is needed to fully understand the molecular and cellular basis of androgen action in regulating the development, differentiation, maturation, migration, and homing of EPCs to the site of injury. A better understanding of these processes will be critical to the development of new therapeutic approaches to the treatment of vascular ED.