CONGENITAL DIAPHRAGMATIC HERNIA INCREASES THE SENSITIVITY OF PULMONARY ARTERIES TO NITRIC OXIDE

Left congenital diaphragmatic hernia (CDH) can lead to pulmonary arteries abnormalities in the contralateral and ipsilateral sides of the diaphragm. Nitric oxide (NO) is the main therapy used to attenuate the vascular effects of CDH, but it is not always effective. We hypothesized that the left and right pulmonary arteries do not respond similarly to NO donors during CDH. Therefore, vasorelaxant responses of the left and right pulmonary arteries to sodium nitroprusside (SNP, a NO donor) were determined in a rabbit experimental model of left CDH. CDH was surgically induced in the fetuses of rabbits on the 25^th day of pregnancy. On the 30^th day of pregnancy, a midline laparotomy was performed to access the fetuses. The fetuses' left and right pulmonary arteries were isolated and mounted in myograph chambers. Vasodilation was evaluated by cumulative concentration-effect curves to SNP. Protein expression of guanylate cyclase isoforms (GCα, GCβ) and the α isoform of cGMP-dependent protein kinase 1 (PKG1α), and the concentration of NO and cGMP were determined in the pulmonary arteries. The left and right pulmonary arteries of newborns with CDH exhibited increased vasorelaxant responses to SNP (i.e. the potency of SNP was increased) compared to the control group. GCα, GCβ, and PKG1α expression were decreased, while NO and cGMP concentrations were increased in the pulmonary arteries of newborns with CDH compared to the control group. The increased cGMP mobilization may be responsible for the increased vasorelaxant responses to the SNP in the pulmonary arteries during left CDH.

Th17 cells-linked mechanisms mediate vascular dysfunction induced by testosterone in a mouse model of gender-affirming hormone therapy

Clinical data point to adverse cardiovascular events elicited by testosterone replacement therapy. Testosterone is the main hormone used in gender-affirming hormone therapy (GAHT) by transmasculine people. However, the cardiovascular impact of testosterone in experimental models of GAHT remains unknown. Sex hormones modulate T cells activation, and immune mechanisms contribute to cardiovascular risk. The present study evaluated whether testosterone negatively impacts female cardiovascular function by enhancing Th17 cells-linked effector mechanisms. Female (8 weeks-old) C57BL/6J mice received testosterone (48 mg.Kg^-1.week^-1) for 8 weeks. Male mice were used for phenotypical comparisons. The hormone-treatment in female mice increased circulating testosterone to levels observed in male mice. Testosterone increased lean body mass and body mass index, and decreased perigonadal fat mass, mimicking clinical findings. After 8 weeks, testosterone decreased endothelium-dependent vasodilation and increased circulating Th17 cells. After 24 weeks, testosterone increased blood pressure in female mice. Ovariectomy did not intensify phenotypical or cardiovascular effects by testosterone. Female mice lacking T and B cells [Rag1 knockout (^-/-)], as well as female mice lacking IL-17 receptor (IL-17Ra^-/-), did not exhibit vascular dysfunction induced by testosterone. Testosterone impaired endothelium-dependent vasodilation in female mice lacking γδ T cells, similarly to the observed in wild type female mice. Adoptive transfer of CD4⁺ T cells restored testosterone-induced vascular dysfunction in Rag1^-/- female mice. Together, these data suggest that CD4⁺ T cells, most likely Th17 cells, are central to vascular dysfunction induced by testosterone in female mice, indicating that changes in immune cells balance are important in the GAHT in transmasculine people.

Testosterone Contributes to Vascular Dysfunction in Young Mice Fed a High Fat Diet by Promoting Nuclear Factor E2-Related Factor 2 Downregulation and Oxidative Stress

Obesity, an important risk factor for cardiovascular disease, promotes vascular oxidative stress. Considering that free testosterone levels remain within the reference range, especially in obese young men and that testosterone stimulates reactive oxygen species (ROS) generation, we sought to investigate whether testosterone interferes with obesity-associated oxidative stress and vascular dysfunction in male mice. We hypothesized that testosterone favors ROS accumulation and vascular dysfunction in high fat diet (HFD)-fed obese mice. We also questioned whether testosterone downregulates the nuclear factor E2–related factor 2 (Nrf2), one of the major cellular defense mechanisms against oxidative stimuli. Male C57Bl/6J mice were submitted to orchiectomy or sham-operation. Mice received either a control diet (CD) or HFD for 18 weeks. Vascular function was assessed in thoracic aortic rings and molecular mechanisms by which testosterone contributes to vascular dysfunction were determined. HFD reduced acetylcholine-induced vasodilation and increased vascular ROS generation in sham mice. Castration prevented these effects. Treatment of castrated mice fed either the CD or HFD with testosterone propionate decreased acetylcholine vasodilation. HFD decreased Nrf2 nuclear accumulation, events linked to decreased mRNA expression and activity of Nrf2-regulated enzymes (catalase, heme oxygenase-1, peroxiredoxin, and thioredoxin). These events were prevented in HFD-fed castrated mice. Bardoxolone, a Nrf2 activator, increased nuclear accumulation of Nrf2, decreased ROS generation and improved acetylcholine vasodilation in HFD-fed sham mice. In vitro, testosterone increased ROS generation and decreased Nrf2 nuclear accumulation. These effects were prevented in the presence of an androgen receptor antagonist, an inhibitor of gene transcription and an inhibitor of the pro-oxidant enzyme NOX-1. These results indicate that testosterone downregulates Nrf2, leading to oxidative stress and vascular dysfunction in HFD-fed obese young mice.

Aryl-hydrocarbon receptor (AhR) activation contributes to high-fat diet-induced vascular dysfunction

BACKGROUND AND PURPOSE

Metabolic and vascular dysfunction are common features of obesity. Aryl hydrocarbons receptors (AhR) regulate lipid metabolism and vascular homeostasis, but whether vascular AhR are activated in obesity or if AhR have protective or harmful effects on vascular function in obesity are not known. Thus, our study addressed whether AhR activation contributes to obesity-associated vascular dysfunction and the mechanisms involved in the AhR effects.

EXPERIMENTAL APPROACH

Male AhRKO (AhR knockout) and WT (wild type) mice were fed either a control or a HF (high-fat) diet for ten weeks. Metabolic and inflammatory parameters were measured in serum and adipose tissue. Vascular reactivity (isometric force) was evaluated using a myography. eNOS and AhR protein expression was determined by Western blot; Cyp1A1 and eNOS gene expression by RT-PCR. Nitric oxide (NO) production was quantified by DAF fluorescence.

KEY RESULTS

HF diet increased serum total, HDL, and LDL cholesterol, as well as vascular AhR protein expression and proinflammatory cytokines in the adipose tissue. HF diet decreased endothelium-dependent vasodilation. AhR deletion protected mice from HF diet-induced dyslipidemia, weight gain, and inflammatory processes. HF diet-induced endothelial dysfunction was attenuated in AhRKO mice. Vessels from AhRKO mice exhibited a greater NO reserve. In cultured endothelial cells, lysophosphatidylcholine (LPC, a major component of LDL and oxLDL) reduced eNOS gene expression and NO production. Antagonism of AhR abrogated LPC effects on endothelial cells and LPC-induced decreased endothelium-dependent vasodilation.

CONCLUSION AND IMPLICATIONS

AhR deletion attenuates HF diet-induced dyslipidemia and vascular dysfunction by improving eNOS/NO signalling. Targeting AhR may prevent obesity-associated vascular dysfunction.

Mitochondrial DNA and TLR9 activation contribute to SARS-CoV-2-induced endothelial cell damage

Background and purpose

Mitochondria play a central role in the host response to viral infection and immunity, being key to antiviral signaling and exacerbating inflammatory processes. Mitochondria and Toll-like receptor (TLR) have been suggested as potential targets in SARS-CoV-2 infection. However, the involvement of TLR9 in SARS-Cov-2-induced endothelial dysfunction and potential contribution to cardiovascular complications in COVID-19 have not been demonstrated. This study determined whether infection of endothelial cells by SARS-CoV-2 affects mitochondrial function and induces mitochondrial DNA (mtDNA) release. We also questioned whether TLR9 signaling mediates the inflammatory responses induced by SARS-CoV-2 in endothelial cells.

Experimental approach

Human umbilical vein endothelial cells (HUVECs) were infected by SARS-CoV-2 and immunofluorescence was used to confirm the infection. Mitochondrial function was analyzed by specific probes and mtDNA levels by real-time polymerase chain reaction (RT-PCR). Inflammatory markers were measured by ELISA, protein expression by western blot, intracellular calcium (Ca²⁺) by FLUOR-4, and vascular reactivity with a myography.

Key results

SARS-CoV-2 infected HUVECs, which express ACE2 and TMPRSS2 proteins, and promoted mitochondrial dysfunction, i.e. it increased mitochondria-derived superoxide anion, mitochondrial membrane potential, and mtDNA release, leading to activation of TLR9 and NF-kB, and release of cytokines. SARS-CoV-2 also decreased nitric oxide synthase (eNOS) expression and inhibited Ca²⁺ responses in endothelial cells. TLR9 blockade reduced SARS-CoV-2-induced IL-6 release and prevented decreased eNOS expression. mtDNA increased vascular reactivity to endothelin-1 (ET-1) in arteries from wild type, but not TLR9 knockout mice. These events were recapitulated in serum samples from COVID-19 patients, that exhibited increased levels of mtDNA compared to sex- and age-matched healthy subjects and patients with comorbidities.

Conclusion and applications

SARS-CoV-2 infection impairs mitochondrial function and activates TLR9 signaling in endothelial cells. TLR9 triggers inflammatory responses that lead to endothelial cell dysfunction, potentially contributing to the severity of symptoms in COVID-19. Targeting mitochondrial metabolic pathways may help to define novel therapeutic strategies for COVID-19.

Angiotensin (1-7)-attenuated vasoconstriction is associated with the Interleukin-10 signaling pathway

AIMS

Angiotensin-1-7 [Ang-(1-7)] is an essential peptide of the renin-angiotensin system that promotes benefits modulating effects in different tissues. Similarly, interleukin-10 (IL-10) exhibits an immunomodulatory action on the vasculature. This study aimed to evaluate whether Ang-(1-7) levels attenuates vascular contractile response, mediated by IL-10-pathway (JAK1/STAT3/IL-10).

MAIN METHODS

Aortas from male mice C57BL/6J and knockout for IL-10 (IL-10^-/-) were incubated with Ang-(1-7) [10 μM] or vehicle, during 5 min, 1 h, 6 h, 12 h, and 24 h. Concentration-response curves to phenylephrine, western blotting, and flow cytometry analysis was performed to evaluate the contractile response, protein expression, and IL-10 levels, respectively.

KEY FINDINGS

Incubation with Ang-(1-7) produced a time-dependent increase in Janus kinases 1 (JAK1) expression, as well as increased expression and activity of the signal transducer and activator of transcription 3 (STAT3) protein. However, this effect was not observed in knockout animals for IL-10. After 12 h of Ang-(1-7) treatment, arteries from control mice displayed decreased vascular reactivity to phenylephrine, but this effect was not observed in the absence of endogenous IL-10. Additionally, incubation with Ang-(1-7) augments IL-10 levels after 6 h, 12 h, and 24 h of incubation.

SIGNIFICANCE

These results demonstrated the role of Ang-(1-7) in the IL-10 signaling pathway and its effects in the vascular contractility response. Thus, these findings suggest a new synergic action where Ang-(1-7) and IL-10 converge into a protective mechanism against vascular dysfunction.

The inflammasome NLRP3 plays a dual role on mouse corpora cavernosa relaxation

NLRP3 plays a role in vascular diseases. Corpora cavernosa (CC) is an extension of the vasculature. We hypothesize that NLRP3 plays a deleterious role in CC relaxation. Male C57BL/6 (WT) and NLRP3 deficient (NLRP3^−/−) mice were used. Intracavernosal pressure (ICP/MAP) measurement was performed. Functional responses were obtained from CC strips of WT and NLRP3^−/− mice before and after MCC950 (NLRP3 inhibitor) or LPS + ATP (NLRP3 stimulation). NLRP3, caspase-1, IL-1β, eNOS, nNOS, guanylyl cyclase-β1 (GCβ1) and PKG1 protein expressions were determined. ICP/MAP and sodium nitroprusside (SNP)-induced relaxation in CC were decreased in NLRP3^−/− mice. Caspase-1, IL-1β and eNOS activity were increased, but PKG1 was reduced in CC of NLRP3^−/−. MCC950 decreased non-adrenergic non-cholinergic (NANC), acetylcholine (ACh), and SNP-induced relaxation in WT mice. MCC950 did not alter NLRP3, caspase-1 and IL-1β, but reduced GCβ1 expression. Although LPS + ATP decreased ACh- and SNP-, it increased NANC-induced relaxation in CC from WT, but not from NLRP3^−/− mice. LPS + ATP increased NLRP3, caspase-1 and interleukin-1β (IL-1β). Conversely, it reduced eNOS activity and GCβ1 expression. NLRP3 plays a dual role in CC relaxation, with its inhibition leading to impairment of nitric oxide-mediated relaxation, while its activation by LPS + ATP causes decreased CC sensitivity to NO and endothelium-dependent relaxation.

Abstract P124: Nlrp3 Activation by Endothelin-1 Mediates Neutrophil Recruitment in Cavernosal Tissue of DOCA/salt Mice

Introduction: Endothelin-1 (ET-1) induces penile detumescence and acts as an important mediator of chronic inflammation. NACHT, leucine reach repeat (LRR) and PYD domain-containing protein 3 (NLRP3) releases the active form of IL-1β. This cytokine is involved in neutrophil recruitment from the circulation to the tissues. Increasing evidence shows that neutrophil infiltration is involved in the genesis and aggravation of various cardiovascular diseases.

Hypothesis: NLRP3 activation by ET-1 mediates neutrophil infiltration in the corpora cavernosa (CC) of DOCA/salt hypertensive mice.

Methods: All protocols were approved by the Animals Use Ethics Committee (CEUA 213/2016). Male C57BL/6 (WT) and NLRP3 deficient mice (NLRP3 -/- ) were either induced to DOCA/salt hypertension or SHAM and treated with bosentan or vehicle. Caspase-1 and IL-1β activities were determined in CC. NF-κB, ICAM-1 and VCAM-1 expressions in CC were determined by immunohistochemistry. Flow cytometry was performed to evaluate the infiltration of myeloid cells into CC.

Results: DOCA/salt hypertension increased caspase-1 and IL-1β activities in CC. NF-κB, ICAM-1, VCAM-1 and neutrophil infiltration were increased in CC of DOCA/salt mice. The treatment with bosentan or the absence of NLRP3 prevented all these alterations in DOCA/salt mice.

Conclusion: ET-1-induced NLRP3 activation is involved in neutrophil recruitment in CC of DOCA/salt hypertensive mice.

Hepatic injury induced by thioacetamide causes aortic endothelial dysfunction by a cyclooxygenase-dependent mechanism

Liver cirrhosis is associated with a wide range of cardiovascular abnormalities including hyperdynamic circulation and cirrhotic cardiomyopathy. The pathogenic mechanisms of these cardiovascular changes are multifactorial and include vascular dysregulations.

AIM

The present study tested the hypothesis that the systemic vascular hyporesponsiveness in thioacetamide (TAA)-induced liver injury model is dependent on nitric oxide (NO) and cyclooxygenase (COX) derivatives.

MAIN METHODS

Wistar rats were treated with TAA for eight weeks to induce liver injury.

KEY FINDINGS

The maximal contractile response in concentration-effect curves to phenylephrine was decreased in aorta from TAA-treated rats, but no differences were found in aorta without endothelium, suggesting an endothelium-dependent mechanism in decreased contractile response. There was no difference in the contractile response with and without L-NAME (N(ω)-nitro-l-arginine methyl ester) in rats with liver injury, showing that the TAA treatment impairs NO synthesis. Pre-incubation of the aorta with indomethacin, a COX-inhibitor, normalized the reduced contractile response to phenylephrine in arteries from TAA group. Also, COX-2 and iNOS (inducible nitric oxide syntase) protein expression was increased in aorta from TAA group compared to control group. Animals submitted to TAA treatment had a reduction in systolic blood pressure. Our findings demonstrated that liver injury induced by TAA caused a decrease in aortic contractile response by a COX-dependent mechanism but not by NO release. Also, it was demonstrated an inflammatory process in the aorta of TAA-treated rats by increased expression of COX-2 and iNOS.

SIGNIFICANCE

Therefore, there is an essential contribution of COX-2 activation in extra-hepatic vascular dysfunction and inflammation present in cirrhosis induced by TAA.

Hypertension: a new treatment for an old disease? Targeting the immune system

Arterial hypertension represents a serious public health problem, being a major cause of morbidity and mortality worldwide. The availability of many antihypertensive therapeutic strategies still fails to adequately treat around 20% of hypertensive patients, who are considered resistant to conventional treatment. In the pathogenesis of hypertension, immune system mechanisms are activated and both the innate and adaptive immune responses play a crucial role. However, what, when and how the immune system is triggered during hypertension development is still largely undefined. In this context, this review highlights scientific advances in the manipulation of the immune system in order to attenuate hypertension and end-organ damage. Here, we discuss the potential use of immunosuppressants and immunomodulators as pharmacological tools to control the activation of the immune system, by non-specific and specific mechanisms, to treat hypertension and improve end-organ damage. Nevertheless, more clinical trials should be performed with these drugs to establish their therapeutic efficacy, safety and risk-benefit ratio in hypertensive conditions. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

O-linked N-acetyl-glucosamine deposition in placental proteins varies according to maternal glycemic levels

AIMS

Hyperglycemia increases glycosylation with O-linked N-acetyl-glucosamine (O-GlcNAc) contributing to placental dysfunction and fetal growth impairment. Our aim was to determine how O-GlcNAc levels are affected by hyperglycemia and the O-GlcNAc distribution in different placental regions.

MAIN METHODS

Female Wistar rats were divided into the following groups: severe hyperglycemia (>300 mg/dL; n = 5); mild hyperglycemia (>140 mg/dL, at least than two time points during oral glucose tolerance test; n = 7) or normoglycemia (<120 mg/dL; n = 6). At 21 days of pregnancy, placental tissue was collected and processed for morphometry and immunohistochemistry analyses, or properly stored at -80 °C for protein quantification by western blot.

KEY FINDINGS

Placental index was increased only in severe hyperglycemic rats. Morphometric analysis showed increased junctional zone and decreased labyrinth region in placentas exclusively from the severe hyperglycemic group. Proteins targeted by O-GlcNAc were detected in all regions, with increased O-GlcNAc levels in the hyperglycemic group compared to control and mild hyperglycemic rats. Proteins in endothelial and trophoblast cells were the main target for O-GlcNAc. Whereas no changes in O-GlcNAc transferase (OGT) expression were detected, O-GlcNAcase (OGA) expression was reduced in placentas from the severe hyperglycemic group and augmented in placentas from the mild hyperglycemic group, compared with their respective control groups.

SIGNIFICANCE

Placental O-GlcNAc overexpression may contribute to placental dysfunction, as indicated by the placental index. Additionally, morphometric alterations, occurring simultaneously with increased O-GlcNAc accumulation in the placental tissue may contribute to placental dysfunction during hyperglycemia.

Mesenteric arteries from stroke-prone spontaneously hypertensive rats exhibit an increase in nitric-oxide-dependent vasorelaxation

The endothelium is crucial for the maintenance of vascular tone by releasing several vasoactive substances, including nitric oxide (NO). Systemic mean arterial pressure is primarily regulated by the resistance vasculature, which has been shown to exhibit increased vascular reactivity, and decreased vasorelaxation during hypertension. Here, we aimed to determine the mechanism for mesenteric artery vasorelaxation of the stroke-prone spontaneously hypertensive rat (SHRSP). We hypothesized that endothelial NO synthase (eNOS) is upregulated in SHRSP vessels, increasing NO production to compensate for the endothelial dysfunction. Concentration-response curves to acetylcholine (ACh) were performed in second-order mesenteric arteries; we observed decreased relaxation responses to ACh (maximum effect elicited by the agonist) as compared with Wistar-Kyoto (WKY) controls. Vessels from SHRSP incubated with N^ω-nitro-l-arginine methyl ester and (or) indomethacin exhibited decreased ACh-mediated relaxation, suggesting a primary role for NO-dependent relaxation. Vessels from SHRSP exhibited a significantly decreased relaxation response with inducible NO synthase (iNOS) inhibition, as compared with WKY vessels. Western blot analysis showed increased total phosphorylated NF-κB, and phosphorylated and total eNOS in SHRSP vessels. Overall, these data suggest a compensatory role for NO by increased eNOS activation. Moreover, we believe that iNOS, although increasing NO bioavailability to compensate for decreased relaxation, leads to a cycle of further endothelial dysfunction in SHRSP mesenteric arteries.

Abstract P422: Two-kidney One Clip (2k1c) Hypertension Reduces Complexity of Heart Rate Variability in Mice

Introduction: Hypertension is the most common chronic cardiovascular disease, being multifactorial in origin and an important cause of morbidity and mortality worldwide. Complex behaviors of heart rate series have been widely recognized and the loss of complexity in heart rate variability (HRV) has been shown to predict adverse cardiovascular outcomes. We hypothesized that two-kidney one clip (2K1C) hypertension reduces the HRV complexity in mice.

Methods and Results: C57BL/6 mice were anesthetized with isoflurane and submitted to 2K1C hypertension by placing a silver clip (0.12 mm) around left renal artery. After 4 weeks, mice were implanted with subcutaneous electrocardiogram (ECG) electrodes and allowed to recover for 48 h. On the day of the experiment, the ECG was recorded for 30 minutes in conscious, unrestrained mice. At the end of the recording, arterial pressure (AP) was directly measured in each mouse under isoflurane anesthesia. RR interval time series were generated and the complexity of HRV was determined using detrending fluctuation analysis (DFA) and multiscale entropy (MSE). Mean AP was higher in 2K1C mice (133±2 vs 93±4 mmHg) while the HR was similar between groups. DFA scaling exponents were calculated in short (5 to 15), mid (30 to 200) and long (200 to 1500) window sizes, but only the long-term exponent was different between groups (1.27±0.09 vs 0.89±0.08 in 2K1C and sham mice, respectively). MSE was calculated up to scale 20 and averaged in short (1 to 5) and long (6 to 20) time scales. In both short (0.75±0.16 vs 1.25±0.11) and long (0.76±0.17 vs 1.22±0.09) ranges, entropy is lower in hypertensive mice.

Conclusions: The complexity of HRV dynamics was found lower in renovascular hypertensive mice. Both sympathetic and vagal control of the heart seems to be involved in this process, as predictability (MSE) and fractality (DFA) is affected in various temporal scales. Nevertheless, the greatest entropy difference between groups is found at scale 6, which is closely related to respiration.

Erectile Dysfunction in Wistar Audiogenic Rats Is Associated With Increased Cavernosal Contraction and Decreased Neuronal Nitric Oxide Synthase Protein Expression

OBJECTIVE

To test the hypothesis that naive Wistar audiogenic rats (WARs) display erectile dysfunction (ED), which is associated with increased sympathetic-mediated contractile tone and decreased nitric oxide-mediated relaxation responses of the cavernous tissue.

METHODS

Changes in the ratio of the maximal intracavernosal pressure-mean arterial pressure after the electrical stimulation of the right major pelvic ganglion were determined in vivo. Cavernosal contractility was induced by electrical field stimulation and phenylephrine. In addition, nonadrenergic-noncholinergic (NANC)-induced relaxation was determined. Rho-kinase (ROCK) pathway proteins, neuronal nitric oxide synthase (nNOS) protein expression, and endothelial nitric oxide synthase (eNOS) and extracellular signal-regulated kinase 1/2 activities were determined by Western blot.

RESULTS

WARs display a significant decrease in maximal intracavernosal pressure-mean arterial pressure responses suggesting ED in this strain. Sympathetic-mediated contractile responses were increased in WARs and contractile responses to phenylephrine were not changed. The increased sympathetic-mediated contractile responses were not associated with changes in the ROCK pathway. On the other hand, NANC-mediated relaxation responses were significantly reduced in WARs. This functional response was accompanied by decreased nNOS and total eNOS protein expressions, augmented phosphorylated eNOS, and decreased extracellular signal-regulated kinase 1/2 phosphorylation levels.

CONCLUSION

Our data have demonstrated that naive WARs display ED in vivo that is associated with increased sympathetic-mediated contractile responses and decreased NANC-mediated relaxation responses. The increase in contractile responses is independent of the ROCK pathway, and the changes in relaxation responses are associated with a decrease in nNOS protein expression, which may activate compensatory mechanisms in the cavernous tissue.

Mitochondrial DNA Activates the NLRP3 Inflammasome and Predisposes to Type 1 Diabetes in Murine Model

Although a correlation between polymorphisms of NOD-like receptor family-pyrin domain containing 3 (NLRP3) and predisposition to type 1 diabetes (T1D) has been identified, the potential function and activation of the NLRP3 inflammasome in T1D have not been clarified. The present study shows that non-obese diabetic mice exhibited increased NLRP3, and pro-IL-1β gene expression in pancreatic lymph nodes (PLNs). Similar increases in gene expression of NLRP3, apoptosis associated speck like protein (ASC) and pro-IL-1β were induced by multiple low doses of streptozotocin (STZ) in C57BL/6 mice. In addition, diabetic C57BL/6 mice also exhibited increased IL-1β protein expression in the pancreatic tissue at day 7, which remained elevated until day 15. Diabetic mice also showed increased positive caspase-1 macrophages in the PLNs, which were decreased in NLRP3^-/- mice, but not in ASC^-/- mice, after STZ treatment. NLRP3- and IL-1R-deficient mice, but not ASC-deficient mice, showed reduced incidence of diabetes, less insulitis, lower hyperglycemia, and normal insulin levels compared to wild-type (WT) diabetic mice. Notably, these mice also displayed a decrease in IL-17-producing CD4 and CD8 T cells (Th17 and Tc17) and IFN-γ-producing CD4 and CD8 T cells (Th1 and Tc1) in the PLNs. Following STZ treatment to induce T1D, NLRP3-deficient mice also exhibited an increase in myeloid-derived suppressor cell and mast cell numbers in the PLNs along with a significant increase in IL-6, IL-10, and IL-4 expression in the pancreatic tissue. Interestingly, diabetic mice revealed increased circulating expression of genes related to mitochondrial DNA, such as cytochrome b and cytochrome c, but not NADH dehydrogenase subunit 6 (NADH). Mitochondrial DNA (mDNA) from diabetic mice, but not from non-diabetic mice, induced significant IL-1β production and caspase-1 activation by WT macrophages, which was reduced in NLRP3^-/- macrophages. Finally, mDNA administration in vivo increased Th17/Tc17/Th1/Tc1 cells in the PLNs and precipitated T1D onset, which was abolished in NLRP3^-/- mice. Overall, our results demonstrate that mDNA-mediated NLRP3 activation triggers caspase-1-dependent IL-1β production and contributes to pathogenic cellular responses during the development of STZ-induced T1D.

Are the innate and adaptive immune systems setting hypertension on fire?

Hypertension is the most common chronic cardiovascular disease and is associated with several pathological states, being an important cause of morbidity and mortality around the world. Low-grade inflammation plays a key role in hypertension and the innate and adaptive immune systems seem to contribute to hypertension development and maintenance. Hypertension is associated with vascular inflammation, increased vascular cytokines levels and infiltration of immune cells in the vasculature, kidneys and heart. However, the mechanisms that trigger inflammation and immune system activation in hypertension are completely unknown. Cells from the innate immune system express pattern recognition receptors (PRR), which detect conserved pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) that induce innate effector mechanisms to produce endogenous signals, such as inflammatory cytokines and chemokines, to alert the host about danger. Additionally, antigen-presenting cells (APC) act as sentinels that are activated by PAMPs and DAMPs to sense the presence of the antigen/neoantigen, which ensues the adaptive immune system activation. In this context, different lymphocyte types are activated and contribute to inflammation and end-organ damage in hypertension. This review will focus on experimental and clinical evidence demonstrating the contribution of the innate and adaptive immune systems to the development of hypertension.

Internal Pudental Artery Dysfunction in Diabetes Mellitus Is Mediated by NOX1-Derived ROS-, Nrf2-, and Rho Kinase-Dependent Mechanisms

Oxidative stress plays an important role in diabetes mellitus (DM)-associated vascular injury. DM is an important risk factor for erectile dysfunction. Functional and structural changes in internal pudendal arteries (IPA) can lead to erectile dysfunction. We hypothesized that downregulation of nuclear factor E2-related factor 2 (Nrf2), consequent to increased nicotinamide adenine dinucleotide phosphate oxidase 1 (NOX1)-derived reactive oxygen species (ROS), impairs IPA function in DM. IPA and vascular smooth muscle cells from C57BL/6 (control) and NOX1 knockout mice were used. DM was induced by streptozotocin in C57BL/6 mice. Functional properties of IPA were assessed using a myograph, protein expression and peroxiredoxin oxidation by Western blot, RNA expression by polymerase chain reaction, carbonylation by oxyblot assay, ROS generation by lucigenin, nitrotyrosine, and amplex red, and Rho kinase activity and nuclear accumulation of Nrf2 by ELISA. IPA from diabetic mice displayed increased contractions to phenylephrine (control 138.5±9.5 versus DM 191.8±15.5). ROS scavenger, Nrf2 activator, NOX1 and Rho kinase inhibitors normalized vascular function. High glucose increased ROS generation in IPA vascular smooth muscle cell. This effect was abrogated by Nrf2 activation and not observed in NOX1 knockout vascular smooth muscle cell. High glucose also increased levels of nitrotyrosine, protein oxidation/carbonylation, and Rho kinase activity, but reduced Nrf2 activity and expression of Nrf2-regulated genes (catalase [25.6±0.05%], heme oxygenase-1 [21±0.1%], and

NAD(P)H

quinone oxidoreductase 1 [22±0.1%]) and hydrogen peroxide levels. These effects were not observed in vascular smooth muscle cell from NOX1 knockout mice. In these cells, high glucose increased hydrogen peroxide levels. In conclusion, Rho kinase activation, via NOX1-derived ROS and downregulation of Nrf2 system, impairs IPA function in DM. These data suggest that Nrf2 is vasoprotective in DM-associated erectile dysfunction.

There is a link between erectile dysfunction and heart failure: it could be inflammation

The rates of erectile dysfunction (ED) in heart failure (HF) are extremely high. Limited capacity of patients with HF to exercise and coronary artery disease are considered to be the main causative mechanisms. Both HF and ED are associated with increased levels of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6) and interleukin-8 (IL- 8). The increased levels of proinflammatory cytokines in ED suggest that inflammatory markers act as important active agents in ED development. The innate immune system also reacts to danger signals released by damaged cells. Damage-associated molecular patterns (DAMPs) are molecules released as a result of tissue injury acting on immune activation during non-infectious inflammation. DAMPs may also reach the circulation and mediate pathophysiological processes that occur in distant organs to the injured site. Cardiomyocytes possess abundant mitochondria and during tissue damage, it is likely that the heart releases high amounts of mitochondrial DNA (mtDNA), which acts as a potent ligand for Toll-like receptor 9 (TLR9). Accordingly, in the present manuscript we review the literature pertaining the relationship between HF and ED and the subjacent inflammatory process associated to both diseases. In addition, we propose the hypothesis that TLR9 activation by DAMPs released in HF leads to inflammation, vascular dysfunction and functional changes in cavernosal tissue, providing an additional mechanism that connects HF to ED. Since TNF-α usually is a product of TLRs activation and seems to be a common link between HF and ED, our hypothesis provide two possible targets to treat the ED associated to HF and may have important preventative and therapeutic implications.

Reactive oxygen species: players in the cardiovascular effects of testosterone

Androgens are essential for the development and maintenance of male reproductive tissues and sexual function and for overall health and well being. Testosterone, the predominant and most important androgen, not only affects the male reproductive system, but also influences the activity of many other organs. In the cardiovascular system, the actions of testosterone are still controversial, its effects ranging from protective to deleterious. While early studies showed that testosterone replacement therapy exerted beneficial effects on cardiovascular disease, some recent safety studies point to a positive association between endogenous and supraphysiological levels of androgens/testosterone and cardiovascular disease risk. Among the possible mechanisms involved in the actions of testosterone on the cardiovascular system, indirect actions (changes in the lipid profile, insulin sensitivity, and hemostatic mechanisms, modulation of the sympathetic nervous system and renin-angiotensin-aldosterone system), as well as direct actions (modulatory effects on proinflammatory enzymes, on the generation of reactive oxygen species, nitric oxide bioavailability, and on vasoconstrictor signaling pathways) have been reported. This mini-review focuses on evidence indicating that testosterone has prooxidative actions that may contribute to its deleterious actions in the cardiovascular system. The controversial effects of testosterone on ROS generation and oxidant status, both prooxidant and antioxidant, in the cardiovascular system and in cells and tissues of other systems are reviewed.

Abstract 014: Nox1-derived ROS Impairs Internal Pudendal Artery Function via Nrf2 and Rho Kinase in Diabetic Mice

Oxidative stress plays an important role in vascular dysfunction in diabetes, an important risk factor for erectile dysfunction (ED). Functional and structural changes in internal pudendal arteries (IPAs), which provide blood supply to the corpus cavernosum, can lead to ED. We hypothesized that downregulation of Nrf2-regulated enzymes, consequent to increased NOX1-derived ROS, impairs IPAs function in diabetic mice. IPAs and cultured vascular smooth muscle cells (VSMC) from C57BL/6 (control) and NOX1 knockout (KO) mice were used; diabetes (DM) was induced by streptozotocin in C57BL/6 mice. Vascular function assessment, by wire myography, demonstrated that IPAs from diabetic mice displayed increased contractility to phenylephrine (Phe, Emax: control 138.5±9.5 vs. DM 191.8±15.5) and decreased endothelial-dependent relaxation to acetylcholine (ACh, Emax: control 98.3±2.65 vs. DM 76.1±4.5). These responses were corrected by incubation of IPAs with tiron (ROS scavenger), bardoxolone (Nrf2 activator), ML171 (NOX1 inhibitor) and Y27632 (Rho Kinase inhibitor). IPAs from diabetic mice exhibited decreased Y276732-induced vasodilatation (LogEC50: control 5.8±0.1 vs. DM 5.3±0.1). Cultured VSMC from IPAs, maintained in high glucose (HG) medium, displayed increased levels of superoxide anion (59.6%±10.43) and nitrotyrosine (40.8%±9.8), as well as decreased NO production (37.7%±10.42) and nuclear accumulation of Nrf2 (20.42%±3.6), effects not observed in VSMC from IPAs isolated from NOX1 KO mice. The expression of Nrf2-regulated genes was also decreased in VSMC from IPAs maintained in HG [catalase (25.6%±0.05), HO-1 (21%±0.1) and NQO-1 (22%±0.1)], an effect prevented by the incubation with ML171. HG decreased H2O2 levels in control VSMC (29%±5.0), but increased H2O2 in NOX1 KO VSMC (45.8%±7.1), effects not observed when cells were pre-incubated with GKT 137831 (NOX1/4 inhibitor). In conclusion, diabetes-associated IPAs dysfunction involves increased NOX-1 derived ROS, decreased expression of Nrf2-regulated enzymes and activation of the Rho kinase pathway. These data suggest that Nrf2 may be vasoprotective in diabetes-associated ED. Financial Support: FAPESP, Brazil.

Diabetes impairs the vascular effects of aldosterone mediated by G protein-coupled estrogen receptor activation

Aldosterone promotes non-genomic effects in endothelial and vascular smooth muscle cells via activation of mineralocorticoid receptors (MR) and G protein-coupled estrogen receptors (GPER). GPER activation is associated with beneficial/protective effects in the vasculature. Considering that vascular dysfunction plays a major role in diabetes-associated complications, we hypothesized that the beneficial effects mediated by vascular GPER activation, in response to aldosterone, are decreased in diabetes. Mesenteric resistance arteries from female, 14-16 weeks-old, control and diabetic (db/db) mice were used. Phenylephrine (PhE)-induced contractions were greater in arteries from db/db vs. control mice. Aldosterone (10 nM) increased maximal contractile responses to PhE in arteries from control mice, an effect elicited via activation of GPER. Although aldosterone did not increase PhE responses in arteries from db/db mice, blockade of GPER, and MR decreased PhE-induced contractile responses in db/db mesenteric arteries. Aldosterone also reduced the potency of acetylcholine (ACh)-induced relaxation in arteries from both control and db/db mice via MR-dependent mechanisms. GPER antagonism further decreased ACh-induced relaxation in the control group, but did not affect ACh responses in the diabetic group. Aldosterone increased extracellular signal-regulated kinase 1/2 phosphorylation in arteries from control and db/db mice by a GPER-dependent mechanism. GPER, but not MR, gene, and protein expression, determined by RT-PCR and immunoblotting/immunofluorescence assays, respectively, were increased in arteries from db/db mice vs. control arteries. These findings indicate that aldosterone activates both vascular MR and GPER and that the beneficial effects of GPER activation are decreased in arteries from diabetic animals. Our results further elucidate the mechanisms by which aldosterone influences vascular function and contributes to vascular dysfunction in diabetes. Financial Support: FAPESP, CNPq, and CAPES, Brazil.

Toll-like receptor 9 plays a key role in the autonomic cardiac and baroreflex control of arterial pressure

The crosstalk between the immune and the autonomic nervous system may impact the cardiovascular function. Toll-like receptors are components of the innate immune system and play developmental and physiological roles. Toll-like receptor 9 (TLR9) is involved in the pathogenesis of cardiovascular diseases, such as hypertension and heart failure. Since such diseases are commonly accompanied by autonomic imbalance and lower baroreflex sensitivity, we hypothesized that TLR9 modulates cardiac autonomic and baroreflex control of arterial pressure (AP). Toll-like receptor 9 knockout (TLR9 KO) and wild-type (WT) mice were implanted with catheters into carotid artery and jugular vein and allowed to recover for 3 days. After basal recording of AP, mice received methyl-atropine or propranolol. AP and pulse interval (PI) variability were evaluated in the time and frequency domain (spectral analysis), as well as by multiscale entropy. Spontaneous baroreflex was studied by sequence technique. Behavioral and cardiovascular responses to fear-conditioning stress were also evaluated. AP was similar between groups, but TLR9 KO mice exhibited lower basal heart rate (HR). AP variability was not different, but PI variability was increased in TLR9 KO mice. The total entropy was higher in TLR9 KO mice. Moreover, baroreflex function was found higher in TLR9 KO mice. Atropine-induced tachycardia was increased in TLR9 KO mice, whereas the propranolol-induced bradycardia was similar to WT mice. TLR9 KO mice exhibit increased behavioral and decreased tachycardia responses to fear-conditioning stress. In conclusion, our findings suggest that TLR9 may negatively modulate cardiac vagal tone and baroreflex in mice.

Abstract 337: G Protein-coupled Estrogen Receptor Contributes To The Vascular Effects Of Aldosterone And Type Two Diabetes-associated Vascular Dysfunction

Aldosterone (Aldo) excess aggravates endothelial dysfunction in diabetes. Aldo exerts its effects via activation of both mineralocorticoid receptors (MR) and G protein-coupled estrogen receptors (GPER). Considering that GPER activation has beneficial effects in the vasculature, we hypothesized that GPER-mediated vascular effects of aldosterone are decreased/abrogated in diabetes. Second-order mesenteric arteries from control (B6BKS-Leprdb/+) and diabetic (db/db) female mice were incubated with 10 nM Aldo, in the presence of either vehicle (veh), the MR antagonist eplerenone (Eple, 10 μM) or the GPER antagonist G15 (1μM), and the effects on phenylephrine (Phe) vascular reactivity were determined. Aldo increased Phe maximal response (Emax, % of KCl contraction) in arteries from control (veh: 112.5±3.2 vs. Aldo: 129.1±2.8 p0.05). In control vessels, Eple did not alter Phe Emax either in the presence of Aldo or veh (p>0.05), whereas G15 abrogated Aldo-induced increase in Phe Emax (Aldo: 129.1±2.8 vs. G15+Aldo: 110.3±3.6 p<0.05). In db/db arteries, the MR and GPER antagonist decreased Phe Emax both in the presence of veh and Aldo (veh: 143.8±4.9 vs Aldo: 136.0±5.2 vs. Eple+veh: 105.4±4.8 vs. Eple+Aldo: 94.6±4.4 vs. G15+veh: 96.4±4.2 vs. G15+Aldo: 104.3±4.1 p<0.05). Arteries from diabetic mice exhibited increased ERK1/2 activation vs. control [arbitrary units (Au), 229.4±3 vs. 100.0±11.8, respectively, p<0.05]. Aldo increased ERK1/2 activation in control (Au, 99.8±0.4 vs. 272.2±58.0 p<0.05) and db/db mice (Au, 99.7±4.0 vs. 162.4±28.2 p<0.05). Eple and G15 reduced Aldo-induced ERK 1/2 activation in control arteries (p<0.05). In db/db arteries, G15 decreased ERK1/2 activation both in the presence of veh and Aldo (Au, Aldo: 162.4±28.2 vs. G15+veh: 81.1±9.1 vs. G15+aldo: 82.7±7.5 p<0.05). In summary, Aldo acutely increases contractile responses to PhE in mesenteric arteries from control animals by GPER-dependent mechanisms. In diabetic animals, both MR and GPER seem to contribute to Aldo effects in the vasculature. Contrary to our hypothesis, GPER contributes to the vascular effects of Aldo in diabetic animals as well as to diabetes-associated vascular dysfunction.

Abstract 339: Chronic Treatment With Fluoxetine Increases Relaxation Of Rat Resistance Mesenteric Arteries Via Atp-sensitive Potassium Channels Activation

Fluoxetine, a selective serotonin reuptake inhibitor (SSRI) has properties that go beyond its antidepressant effects and alters mechanisms involved in the regulation of vasomotor tone. While there are many studies demonstrating the acute effects of fluoxetine in the vasculature, studies on the chronic effects of this SSRI are still limited. Here we postulated that chronic treatment with fluoxetine enhances vascular reactivity to vasodilator stimuli by increasing nitric oxide (NO) signaling. The effects of chronic treatment with fluoxetine on vascular reactivity were determined in resistance mesenteric arteries from Wistar rats, which were treated with (I) vehicle (water for 21 days) or (II) fluoxetine (10 mg/kg/day for 21 days in the drinking water). Fluoxetine treatment increased endothelium-dependent (pEC50, Veh = -7.08±0.07; Fluox = -7.4±0.11, p<0.05) and -independent relaxant response (pEC50, Veh = -7.75±0.08; Fluox = -8.5 ± 0.11, p<0.05). Fluoxetine also increased vascular NOx (NO metabolites) levels (Veh = 1.2±0.13 μM/μg; Fluox = 2.0 ± 0.13 μM/μg, p <0.05), nitric oxide sintase (NOS) activity (Fluox = 76%) and phosphorylation of endothelial NOS (eNOS) at serine1177 [arbitrary units (a.u.), Veh = 0.36±0.10; Fluox = 1.2 ± 0.08, p <0.05]. Fluoxetine treatment did not change neuronal NOS (nNOS) or soluble guanylate cyclase (sGC) expression neither vascular responses to cyclic guanosine monophosphate (cGMP) or sGC activators. However, pinacidil- (KATP channels activator)-induced relaxation was increased by fluoxetine treatment (pEC50, Veh = -5.9±0.12; Fluox = -6.5±0.17, p>0.05). In conclusion, chronic treatment with fluoxetine increases endothelium-dependent and -independent relaxation response in resistance mesenteric arteries by mechanisms that involve increased NOS activity, NO generation and KATP channels activation. These effects may contribute to the cardiovascular side effects associated with fluoxetine treatment.

Abstract 353: Castration Impairs Rat Internal Pudendal Artery Reactivity And Structure

Testosterone deficiency is strongly associated with erectile dysfunction (ED). Inadequate penile arterial flow is one of the major causes of ED. Considering that blood flow to the corpus cavernosum is derived from the internal pudendal arteries (IPA), we hypothesized that castration induces impairment of IPAs reactivity and structure, contributing to ED. Male Wistar rats were studied 30 days after castration (Cast). Functional and structural properties of rat IPA were determined in wire and pressure myograph systems, respectively. Castrated rats exhibited impaired erectile function, represented by decreased intracavernosal pressure/mean arterial pressure ratio [ICP/MAP (sham = 0.5 ± 0.1; castrated = 0.2 ± 0.1; 20 Hz. p <0.05)]. Castrated rats exhibited decreased phenylephrine (Phe)- [(% Kcl) Control: 175.4 ± 4.6 vs Cast: 134,9 ± 11; Emax] and electrical field stimulation (EFS)-induced contraction [(% Kcl) Control: 213,0 ± 7.1 vs Cast: 137 ± 6.1; 12Hz] and decreased acetylcholine (ACh)- (Control: 79.7 ± 2.2 vs Cast: 49.8 ± 2.8; Emax) and EFS-induced vasodilatation (Control: 54.6 ± 2.1 vs Cast: 35.5 ± 1.6; 12hz). IPAs from Cast rats exhibited decreased internal diameter [Control (μm): 499.9 ± 35.9 vs Cast: 413.0 ± 14.8; 60 mmHg], external diameter [Control (μm): 669.4 ± 40.1 vs Cast: 552.0 ± 30.0; 60 mmHg], thickness of the arterial wall [Control (μm): 81.2 ± 6.4 vs Cast: 55.8 ± 7.5; 80 mmHg] and cross-sectional area [Control (μm2): 157217 ± 12533 vs Cast: 116383 ± 12424; 30 mmHg]. Castration decreased nNOS expression (60%) and increased p38 (Thr180/Tyr182) phosphorylation (450%), as well as cleavage of caspase 3 (270%). In conclusion, testosterone deficiency is associated with impairment of IPA reactivity and structure and increased apoptosis signalling markers. Our findings suggest that hypogonadism may contribute to IPA dysfunction, which can leads to ED. Financial support: FAPESP and CNPq.

Abstract 268: Toll-like Receptor 9 (TLR9) Plays a Key Role in the Autonomic Cardiac and Baroreflex Control of Arterial Pressure

Introduction: The crosstalk between the immune and nervous system can impact cardiovascular regulation. Toll-like receptor 9 (TLR9) is expressed in immune cells, peripheral nerves and vascular smooth muscle cells. TLR9 is involved in hypertension and cholinergic stimulation suppresses immune responses mediated by TLR9. Based on that, we hypothesized that TLR9 plays a role in cardiac autonomic and baroreflex control of arterial pressure (AP).

Methods and Results: TLR9 knockout (KO) and WT mice were anesthetized with isoflurane, implanted with catheters into left carotid artery and right jugular vein and allowed to recovery for 3 days. After basal recording of AP, mice received cardiac autonomic receptor blockers methyl atropine or propranolol. AP and pulse interval (PI) variability were evaluated using the symbolic analysis (non-linear method). Spontaneous baroreflex was evaluated by sequence technique. Mean AP was slightly higher in TLR9 KO (TLR9 KO: 126±2.8 vs WT: 115±4.4 mmHg). In the symbolic analysis the 0V pattern was lower (TLR9 KO: 20±5.4 vs WT: 35±5.0 %) and 2LV pattern was higher in the TLR9 KO (TLR9 KO: 6±1.6 vs WT: 2±0.5 %), an indication of sympathetic and parasympathetic activity, respectively. AP/PI sequences were similar between groups. However, the gain of AP/PI sequences was increased in TLR9 KO (TLR9 KO: 5±1.4 vs WT: 2±0.4 ms/mmHg). Atropine-induced tachycardia was increased in TLR9 KO (TLR9 KO: 23±8.0 vs WT: 2±0.7 ms), whereas propranolol-induced bradycardia was decreased (28±11.0 vs WT: 56±7.6 ms).

Conclusions: Our findings demonstrate that TLR9 negatively modulates cardiac vagal tone, and consequently the baroreflex control of AP.

Pyk2 mediates increased adrenergic contractile responses in arteries from DOCA-salt mice - VASOACTIVE PEPTIDE SYMPOSIUM

BACKGROUND

The calcium-dependent proline-rich tyrosine kinase (Pyk2), a nonreceptor protein activated by tyrosine phosphorylation, links G protein-coupled receptors to vascular responses. We tested the hypothesis that enhanced vascular reactivity in DOCA-salt hypertensive mice are due to increased activation of Pyk2.

METHODS AND RESULTS

Aorta and small mesenteric arteries from DOCA-salt and uninephrectomized (UNI) male C57Bl/6 mice were used. Systolic blood pressure (mmHg) was higher in DOCA (126+/-3) vs. UNI (100+/-4) mice. Vascular responses to phenylephrine (1nM to 100muM) were greater both in aorta and small mesenteric arteries from DOCA-salt than UNI, but treatment with Tyrphostin A-9 (0.1muM, Pyk2 inhibitor) abolished the difference among the groups. Pyk2 levels, as well as phospho-Pyk2(Tyr402), paxillin and phospho-paxillin(Tyr118) were increased in DOCA-salt aorta. Incubation of vessels with Tyrphostin A-9 restored phosphorylation of Pyk2 and paxillin.

CONCLUSION

Increased activation of Pyk2 contributes to increased vascular contractile-responses in DOCA-salt mice.

Increased vascular O-GlcNAcylation augments reactivity to constrictor stimuli - VASOACTIVE PEPTIDE SYMPOSIUM

BACKGROUND

O-Linked N-acetylglucosaminylation (O-GlcNAcylation) plays a role in many aspects of protein function. Whereas elevated O-GlcNAc levels contribute to diabetes related end-organ damage, O-GlcNAcylation is also physiologically important. Because proteins that play a role in vascular tone regulation can be O-GlcNAcylated, we hypothesized that O-GlcNAcylation increases vascular reactivity to constrictor stimuli.

METHODS AND RESULTS

Aortas from male Sprague-Dawley rats and C57BL/6 mice were incubated for 24 h with vehicle or PugNAc (O-GlcNAcase inhibitor, 100muM). PugNAc incubation significantly increased O-GlcNAc-proteins, as determined by Western blot. PugNAc also increased vascular contractions to phenylephrine and serotonin, an effect not observed in the presence of L-NAME or in endothelium-denuded vessels. Acetylcholine-induced relaxation, but not that to sodium nitroprusside was decreased by PugNAc treatment, an effect accompanied by decreased levels of phosphorylated eNOS(Ser-1177) and Akt(Ser-473).

CONCLUSION

Augmented O-GlcNAcylation increases vascular reactivity to constrictor stimuli, possibly due to its effects on eNOS expression and activity, reinforcing the concept that O-GlcNAcylation modulates vascular reactivity and may play a role in pathological conditions associated with abnormal vascular function.

Mendelian inheritance, linkage and genotypic disequilibrium in microsatellite loci isolated from Hymenaea courbaril (Leguminosae)

The Neotropical tree Hymenaea courbaril, locally known as Jatobá, is a valuable source of lumber and also produces comestible and medicinal fruit. We characterized Mendelian inheritance, linkage and genotypic disequilibrium at nine microsatellite loci isolated from H. courbaril, in order to determine if they would provide accurate estimates of population genetic parameters of this important Amazon species. The study was made on 250 open-pollinated offspring originated from 14 seed trees. Only one of nine loci presented significant deviation from the expected Mendelian segregation (1:1). Genotypic disequilibrium between pairwise loci was investigated based on samples from 55 adult and 56 juvenile trees. No genetic linkage between any paired loci was observed. After Bonferroni's corrections for multiple tests, we found no evidence of genotypic disequilibrium between pairs of loci. We conclude that this set of loci can be used for genetic diversity/ structure, mating system, gene flow, and parentage analyses in H. courbaril populations.

Differential modulation of nitric oxide synthases in aging: therapeutic opportunities

Vascular aging is the term that describes the structural and functional disturbances of the vasculature with advancing aging. The molecular mechanisms of aging-associated endothelial dysfunction are complex, but reduced nitric oxide (NO) bioavailability and altered vascular expression and activity of NO synthase (NOS) enzymes have been implicated as major players. Impaired vascular relaxation in aging has been attributed to reduced endothelial NOS (eNOS)-derived NO, while increased inducible NOS (iNOS) expression seems to account for nitrosative stress and disrupted vascular homeostasis. Although eNOS is considered the main source of NO in the vascular endothelium, neuronal NOS (nNOS) also contributes to endothelial cells-derived NO, a mechanism that is reduced in aging. Pharmacological modulation of NO generation and expression/activity of NOS isoforms may represent a therapeutic alternative to prevent the progression of cardiovascular diseases. Accordingly, this review will focus on drugs that modulate NO bioavailability, such as nitrite anions and NO-releasing non-steroidal anti-inflammatory drugs, hormones (dehydroepiandrosterone and estrogen), statins, resveratrol, and folic acid, since they may be useful to treat/to prevent aging-associated vascular dysfunction. The impact of these therapies on life quality in elderly and longevity will be discussed.

Testosterone and vascular function in aging

Androgen receptors are widely distributed in several tissues, including vascular endothelial and smooth muscle cells. Through classic cytosolic androgen receptors or membrane receptors, testosterone induces genomic and non-genomic effects, respectively. Testosterone interferes with the vascular function by increasing the production of pro-inflammatory cytokines and arterial thickness. Experimental evidence indicates that sex steroid hormones, such as testosterone modulate the synthesis and bioavailability of NO and, consequently, endothelial function, which is key for a healthy vasculature. Of interest, aging itself is accompanied by endothelial and vascular smooth muscle dysfunction. Aging-associated decline of testosterone levels is accompanied by age-related diseases, such as metabolic and cardiovascular diseases, indicating that very low levels of androgens may contribute to cardiovascular dysfunction observed in these age-related disorders or, in other words, that testosterone may have beneficial effects in the cardiovascular system. However, testosterone seems to play a negative role in the severity of renal disease. In this mini-review, we briefly comment on the interplay between aging and testosterone levels, the vascular actions of testosterone and its implications for vascular aging. Renal effects of testosterone and the use of testosterone to prevent vascular dysfunction in elderly are also addressed.

STIM1/Orai1-mediated store-operated Ca2+ entry: the tip of the iceberg

Highly efficient mechanisms regulate intracellular calcium (Ca2+) levels. The recent discovery of new components linking intracellular Ca2+ stores to plasma membrane Ca2+ entry channels has brought new insight into the understanding of Ca2+ homeostasis. Stromal interaction molecule 1 (STIM1) was identified as a Ca2+ sensor essential for Ca2+ store depletion-triggered Ca2+ influx. Orai1 was recognized as being an essential component for the Ca2+ release-activated Ca2+ (CRAC) channel. Together, these proteins participate in store-operated Ca2+ channel function. Defective regulation of intracellular Ca2+ is a hallmark of several diseases. In this review, we focus on Ca2+ regulation by the STIM1/Orai1 pathway and review evidence that implicates STIM1/Orai1 in several pathological conditions including cardiovascular and pulmonary diseases, among others.

Emerging role for TNF-α in erectile dysfunction

INTRODUCTION

A role for cytokines in the pathophysiology of erectile dysfunction (ED) has emerged. Cytokines induce genes that synthesize other peptides in the cytokine family and several mediators, such as prostanoids, leukotrienes, nitric oxide, bradykinin, reactive oxygen species, and platelet-activating factor, all of which can affect vascular function. Consistent with the fact that the cavernosal tissue is a complex extension of the vasculature, risk factors that affect the vasculature have been shown to affect cavernosal function as well. Accordingly, the penile tissue has been recognized as an early sentinel for atherosclerosis that underlies coronary artery disease and cardiovascular diseases (CVD).

AIM

To review the literature pertaining to the role of tumor necrosis factor-alpha (TNF-α) in ED.

METHODS

PubMed search for pertinent publications on the role of cytokines, particularly TNF-α, in CVD and ED.

MAIN OUTCOME MEASURES

Clinical and experimental evidence demonstrates that TNF-α may play a role in ED.

RESULTS

TNF-α has been shown to play an important role in CVD, mainly due to its direct effects on the vasculature. In addition, high levels of TNF-α were demonstrated in patients with ED. In this review, we present a short description of the physiology of erection and the cytokine network. We focus on vascular actions of TNF-α that support a role for this cytokine as a potential candidate in the pathophysiology of ED, particularly in the context of CVD. A brief overview of its discovery, mechanisms of synthesis, receptors, and its main actions on the systemic and penile vasculature is also presented.

CONCLUSIONS

Considering that ED results from a systemic arterial defect not only confined to the penile vasculature, implication of TNF-α in the pathophysiology of ED offers a humoral linking between CVD and ED.

Decreased cGMP level contributes to increased contraction in arteries from hypertensive rats: role of phosphodiesterase 1

Recent evidence suggests that angiotensin II (Ang II) upregulates phosphodiesterase (PDE) 1A expression. We hypothesized that Ang II augmented PDE1 activation, decreasing the bioavailability of cyclic guanosine 3' 5'-monophosphate (cGMP), and contributing to increased vascular contractility. Male Sprague-Dawley rats received mini-osmotic pumps with Ang II (60 ng·min(-1)) or saline for 14 days. Phenylephrine (PE)-induced contractions were increased in aorta (E(max)168% ± 8% vs 136% ± 4%) and small mesenteric arteries (SMA; E(max)170% ± 6% vs 143% ± 3%) from Ang II-infused rats compared to control. PDE1 inhibition with vinpocetine (10 μmol/L) reduced PE-induced contraction in aortas from Ang II rats (E(max)94% ± 12%) but not in controls (154% ± 7%). Vinpocetine decreased the sensitivity to PE in SMA from Ang II rats compared to vehicle (-log of half maximal effective concentration 5.1 ± 0.1 vs 5.9 ± 0.06), but not in controls (6.0 ± 0.03 vs 6.1 ± 0.04). Sildenafil (10 μmol/L), a PDE5 inhibitor, reduced PE-induced maximal contraction similarly in Ang II and control rats. Arteries were contracted with PE (1 μmol/L), and concentration-dependent relaxation to vinpocetine and sildenafil was evaluated. Aortas from Ang II rats displayed increased relaxation to vinpocetine compared to control (E(max)82% ± 12% vs 445 ± 5%). SMA from Ang II rats showed greater sensitivity during vinpocetine-induced relaxation compared to control (-log of half maximal effective concentration 6.1 ± 0.3 vs 5.3 ± 0.1). No differences in sildenafil-induced relaxation were observed. PDE1A and PDE1C expressions in aorta and PDE1A expression in SMA were increased in Ang II rats. cGMP production, which is decreased in arteries from Ang II rats, was restored after PDE1 blockade. We conclude that PDE1 activation reduces cGMP bioavailability in arteries from Ang II, contributing to increased contractile responsiveness.

O-GlcNAcylation contributes to the vascular effects of ET-1 via activation of the RhoA/Rho-kinase pathway

AIMS

Glycosylation with β-N-acetylglucosamine (O-GlcNAcylation) is one of the most complex post-translational modifications. The cycling of O-GlcNAc is controlled by two enzymes: UDP-NAc transferase (OGT) and O-GlcNAcase (OGA). We recently reported that endothelin-1 (ET-1) augments vascular levels of O-GlcNAcylated proteins. Here we tested the hypothesis that O-GlcNAcylation contributes to the vascular effects of ET-1 via activation of the RhoA/Rho-kinase pathway.

METHODS AND RESULTS

Incubation of vascular smooth muscle cells (VSMCs) with ET-1 (0.1 μM) produces a time-dependent increase in O-GlcNAc levels. ET-1-induced O-GlcNAcylation is not observed when VSMCs are previously transfected with OGT siRNA, treated with ST045849 (OGT inhibitor) or atrasentan (ET(A) antagonist). ET-1 as well as PugNAc (OGA inhibitor) augmented contractions to phenylephrine in endothelium-denuded rat aortas, an effect that was abolished by the Rho kinase inhibitor Y-27632. Incubation of VSMCs with ET-1 increased expression of the phosphorylated forms of myosin phosphatase target subunit 1 (MYPT-1), protein kinase C-potentiated protein phosphatase 1 inhibitor protein (protein kinase C-potentiated phosphatase inhibitor-17), and myosin light chain (MLC) and RhoA expression and activity, and this effect was abolished by both OGT siRNA transfection or OGT inhibition and atrasentan. ET-1 also augmented expression of PDZ-Rho GEF (guanine nucleotide exchange factor) and p115-Rho GEF in VSMCs and this was prevented by OGT siRNA, ST045849, and atrasentan.

CONCLUSION

We suggest that ET-1 augments O-GlcNAcylation and this modification contributes to increased vascular contractile responses via activation of the RhoA/Rho-kinase pathway.

Erectile dysfunction in young non-obese type II diabetic Goto-Kakizaki rats is associated with decreased eNOS phosphorylation at Ser1177

INTRODUCTION

Diabetes mellitus (DM) is a risk factor for erectile dysfunction (ED). Although type 2 DM is responsible for 90-95% diabetes cases, type 1 DM experimental models are commonly used to study diabetes-associated ED.

AIM

Goto-Kakizaki (GK) rat model is relevant to ED studies since the great majority of patients with type 2 diabetes display mild deficits in glucose-stimulated insulin secretion, insulin resistance, and hyperglycemia. We hypothesized that GK rats display ED which is associated with decreased nitric oxide (NO) bioavailability.

METHODS

Wistar and GK rats were used at 10 and 18 weeks of age. Changes in the ratio of intracavernosal pressure/mean arterial pressure (ICP/MAP) after electrical stimulation of cavernosal nerve were determined in vivo. Cavernosal contractility was induced by electrical field stimulation (EFS) and phenylephrine (PE). In addition, nonadrenergic-noncholinergic (NANC)- and sodium nitroprusside (SNP)-induced relaxation were determined. Cavernosal neuronal nitric oxide synthase (nNOS) and endothelial nitric oxide synthase (eNOS) mRNA and protein expression were also measured.

MAIN OUTCOME MEASURE

GK diabetic rats display ED associated with decreased cavernosal expression of eNOS protein.

RESULTS

GK rats at 10 and 18 weeks demonstrated impaired erectile function represented by decreased ICP/MAP responses. Ten-week-old GK animals displayed increased PE responses and no changes in EFS-induced contraction. Conversely, contractile responses to EFS and PE were decreased in cavernosal tissue from GK rats at 18 weeks of age. Moreover, GK rats at 18 weeks of age displayed increased NANC-mediated relaxation, but not to SNP. In addition, ED was associated with decreased eNOS protein expression at both ages.

CONCLUSION

Although GK rats display ED, they exhibit changes in cavernosal reactivity that would facilitate erectile responses. These results are in contrast to those described in other experimental diabetes models. This may be due to compensatory mechanisms in cavernosal tissue to overcome restricted pre-penile arterial blood supply or impaired veno-occlusive mechanisms.

O-GlcNAcylation contributes to augmented vascular reactivity induced by endothelin 1

O-GlcNAcylation augments vascular contractile responses, and O-GlcNAc-proteins are increased in the vasculature of deoxycorticosterone-acetate salt rats. Because endothelin 1 (ET-1) plays a major role in vascular dysfunction associated with salt-sensitive forms of hypertension, we hypothesized that ET-1-induced changes in vascular contractile responses are mediated by O-GlcNAc modification of proteins. Incubation of rat aortas with ET-1 (0.1 mumol/L) produced a time-dependent increase in O-GlcNAc levels and decreased expression of O-GlcNAc transferase and beta-N-acetylglucosaminidase, key enzymes in the O-GlcNAcylation process. Overnight treatment of aortas with ET-1 increased phenylephrine vasoconstriction (maximal effect [in moles]: 19+/-5 versus 11+/-2 vehicle). ET-1 effects were not observed when vessels were previously instilled with anti-O-GlcNAc transferase antibody or after incubation with an O-GlcNAc transferase inhibitor (3-[2-adamantanylethyl]-2-[{4-chlorophenyl}azamethylene]-4-oxo-1,3-thiazaperhyd roine-6-carboxylic acid; 100 mumol/L). Aortas from deoxycorticosterone-acetate salt rats, which exhibit increased prepro-ET-1, displayed increased contractions to phenylephrine and augmented levels of O-GlcNAc proteins. Treatment of deoxycorticosterone-acetate salt rats with an endothelin A antagonist abrogated augmented vascular levels of O-GlcNAc and prevented increased phenylephrine vasoconstriction. Aortas from rats chronically infused with low doses of ET-1 (2 pmol/kg per minute) exhibited increased O-GlcNAc proteins and enhanced phenylephrine responses (maximal effect [in moles]: 18+/-2 versus 10+/-3 control). These changes are similar to those induced by O-(2-acetamido-2-deoxy-d-glucopyranosylidene) amino-N-phenylcarbamate, an inhibitor of beta-N-acetylglucosaminidase. Systolic blood pressure (in millimeters of mercury) was similar between control and ET-1-infused rats (117+/-3 versus 123+/-4 mm Hg; respectively). We conclude that ET-1 indeed augments O-GlcNAc levels and that this modification contributes to the vascular changes induced by this peptide. Increased vascular O-GlcNAcylation by ET-1 may represent a mechanism for hypertension-associated vascular dysfunction or other pathological conditions associated with increased levels of ET-1.

Extracellular signal-regulated kinase 1/2 activation, via downregulation of mitogen-activated protein kinase phosphatase 1, mediates sex differences in desoxycorticosterone acetate-salt hypertension vascular reactivity

Extracellular signal-regulated kinase (ERK)1/2 has been reported to play a role in vascular dysfunction associated with mineralocorticoid hypertension. We hypothesized that, compared with female rats, an upregulation of ERK1/2 signaling in the vasculature of male rats contributes to augmented contractile responses in mineralocorticoid hypertension. Uninephrectomized male and female Sprague-Dawley rats received desoxycorticosterone acetate (DOCA) pellets (200 mg per animal) and saline to drink for 3 weeks. Control uninephrectomized rats received tap water to drink. Blood pressure, measured by telemetry, was significantly higher in male DOCA rats (191+/-3 mm Hg) compared with female DOCA rats (172+/-7 mm Hg; n=5). DOCA treatment resulted in augmented contractile responses to phenylephrine in aorta (22+/-3 mN; n=6) and small mesenteric arteries (13+/-2 mN; n=6) from male DOCA rats versus uninephrectomized male rats (16+/-3 and 10+/-2 mN, respectively; P<0.05) and female DOCA rats (15+/-1 and 11+/-1 mN, respectively). ERK1/2 inhibition with PD-98059 (10 micromol/L) abrogated increased contraction to phenylephrine in aorta (14+/-2 mN) and small mesenteric arteries (10+/-2 mN) from male DOCA rats, without any effects in arteries from male uninephrectomized or female animals. Compared with the other groups, phosphorylated ERK1/2 levels were increased in the aorta from male DOCA rats, whereas mitogen-activated protein kinase phosphatase 1 expression was decreased. Interleukin-10 plasma levels, which positively regulate mitogen-activated protein kinase phosphatase 1 activity, were reduced in male DOCA-salt rats. We speculate that augmented vascular reactivity in male hypertensive rats is mediated via activation of the ERK1/2 pathway. In addition, mitogen-activated protein kinase phosphatase 1 and interleukin 10 play regulatory roles in this process.

A key role for Na+/K+-ATPase in the endothelium-dependent oscillatory activity of mouse small mesenteric arteries

Oscillatory contractile activity is an inherent property of blood vessels. Various cellular mechanisms have been proposed to contribute to oscillatory activity. Mouse small mesenteric arteries display a unique low frequency contractile oscillatory activity (1 cycle every 10-12 min) upon phenylephrine stimulation. Our objective was to identify mechanisms involved in this peculiar oscillatory activity. First-order mesenteric arteries were mounted in tissue baths for isometric force measurement. The oscillatory activity was observed only in vessels with endothelium, but it was not blocked by L-NAME (100 microM) or indomethacin (10 microM), ruling out the participation of nitric oxide and prostacyclin, respectively, in this phenomenon. Oscillatory activity was not observed in vessels contracted with K+ (90 mM) or after stimulation with phenylephrine plus 10 mM K+. Ouabain (1 to 10 microM, an Na+/K+-ATPase inhibitor), but not K+ channel antagonists [tetraethylammonium (100 microM, a nonselective K+ channel blocker), Tram-34 (10 microM, blocker of intermediate conductance K+ channels) or UCL-1684 (0.1 microM, a small conductance K+ channel blocker)], inhibited the oscillatory activity. The contractile activity was also abolished when experiments were performed at 20 degrees C or in K+-free medium. Taken together, these results demonstrate that Na+/K+-ATPase is a potential source of these oscillations. The presence of alpha-1 and alpha-2 Na+/K+-ATPase isoforms was confirmed in murine mesenteric arteries by Western blot. Chronic infusion of mice with ouabain did not abolish oscillatory contraction, but up-regulated vascular Na+/K+-ATPase expression and increased blood pressure. Together, these observations suggest that the Na+/K+ pump plays a major role in the oscillatory activity of murine small mesenteric arteries.

Upregulation of intermediate calcium-activated potassium channels counterbalance the impaired endothelium-dependent vasodilation in stroke-prone spontaneously hypertensive rats

Endothelial dysfunction has been linked to a decrease in nitric oxide (NO) bioavailability and attenuated endothelium-derived hyperpolarizing factor (EDHF)-mediated relaxation. The small (SK(Ca)) and intermediate (IK(Ca)) calcium-activated potassium channels play a key role in endothelium-dependent relaxation. Because the repressor element 1-silencing transcription factor (REST) negatively regulates IK(Ca) expression, we hypothesized that augmented REST and decreased IK(Ca) expression contributes to impaired endothelium-dependent vasodilation associated with hypertension. Acetylcholine (ACh) responses were slightly decreased in small mesenteric arteries from male stroke-prone spontaneously hypertensive rats (SHRSPs) versus arteries from Wistar Kyoto (WKY) rats. Incubation with N-nitro-L-arginine methyl ester (L-NAME; 100mumol/L) and indomethacin (100mumol/L) greatly impaired ACh responses in vessels from SHRSP. Iberiotoxin (0.1mumol/L), which is a selective inhibitor of large-conductance K(Ca) (BK(Ca)) channels, did not modify EDHF-mediated vasodilation in SHRSP or WKY. UCL-1684 (0.1mumol/L), which is a selective inhibitor of SKCa channels, almost abolished EDHF-mediated vasodilation in WKY and decreased relaxation in SHRSP. 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34; 10mumol/L) and charybdotoxin (0.1mumol/L), which are both IKCa inhibitors, produced a small decrease of EDHF relaxation in WKY but completely abrogated EDHF vasodilation in SHRSP. EDHF-mediated relaxant responses were completely abolished in both groups by simultaneous treatment with UCL-1684 and TRAM-34 or charybdotoxin. Relaxation to SK(Ca)/IK(Ca) channels agonist NS-309 was decreased in SHRSP arteries. The expression of SK(Ca) was decreased, whereas IK(Ca) was increased in SHRSP mesenteric arteries. REST expression was reduced in arteries from SHRSP. Vessels incubated with TRAM-34 (10mumol/L) for 24h displayed reduced REST expression and demonstrated no differences in IK(Ca). In conclusion, IK(Ca) channel upregulation, via decreased REST, seems to compensate deficient activity of SK(Ca) channels in the vasculature of spontaneously hypertensive rats.

TNF-alpha infusion impairs corpora cavernosa reactivity

INTRODUCTION

Erectile dysfunction (ED), as well as cardiovascular diseases (CVDs), is associated with endothelial dysfunction and increased levels of proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha).

AIM

We hypothesized that increased TNF-alpha levels impair cavernosal function.

METHODS

In vitro organ bath studies were used to measure cavernosal reactivity in mice infused with vehicle or TNF-alpha (220 ng/kg/min) for 14 days. Gene expression of nitric oxide synthase isoforms was evaluated by real-time polymerase chain reaction.

MAIN OUTCOME MEASURES

Corpora cavernosa from TNF-alpha-infused mice exhibited decreased nitric oxide (NO)-dependent relaxation, which was associated with decreased endothelial nitric oxide synthase (eNOS) and neuronal nitric oxide synthase (nNOS) cavernosal expression.

RESULTS

Cavernosal strips from the TNF-alpha-infused mice displayed decreased nonadrenergic-noncholinergic (NANC)-induced relaxation (59.4 +/- 6.2 vs. control: 76.2 +/- 4.7; 16 Hz) compared with the control animals. These responses were associated with decreased gene expression of eNOS and nNOS (P < 0.05). Sympathetic-mediated, as well as phenylephrine (PE)-induced, contractile responses (PE-induced contraction; 1.32 +/- 0.06 vs. control: 0.9 +/- 0.09, mN) were increased in cavernosal strips from TNF-alpha-infused mice. Additionally, infusion of TNF-alpha increased cavernosal responses to endothelin-1 and endothelin receptor A subtype (ET(A)) receptor expression (P < 0.05) and slightly decreased tumor necrosis factor-alpha receptor 1 (TNFR1) expression (P = 0.063).

CONCLUSION

Corpora cavernosa from TNF-alpha-infused mice display increased contractile responses and decreased NANC nerve-mediated relaxation associated with decreased eNOS and nNOS gene expression. These changes may trigger ED and indicate that TNF-alpha plays a detrimental role in erectile function. Blockade of TNF-alpha actions may represent an alternative therapeutic approach for ED, especially in pathologic conditions associated with increased levels of this cytokine.

TNF-alpha knockout mice have increased corpora cavernosa relaxation

INTRODUCTION

Erectile dysfunction is considered an early clinical manifestation of vascular disease and an independent risk factor for cardiovascular events associated with endothelial dysfunction and increased levels of pro-inflammatory cytokines. Tumor necrosis factor-alpha (TNF-alpha), a pro-inflammatory cytokine, suppresses endothelial nitric oxide synthase (eNOS) expression.

AIM

Considering that nitric oxide (NO) is of critical importance in penile erection, we hypothesized that blockade of TNF-alpha actions would increase cavernosal smooth muscle relaxation.

METHODS

In vitro organ bath studies were used to measure cavernosal reactivity in wild type and TNF-alpha knockout (TNF-alpha KO) mice and NOS expression was evaluated by western blot. In addition, spontaneous erections (in vivo) were evaluated by videomonitoring the animals (30 minutes). Collagen and elastin expression were evaluated by Masson trichrome and Verhoff-van Gieson stain reaction, respectively.

MAIN OUTCOME MEASURES

Corpora cavernosa from TNF-alpha KO mice exhibited increased NO-dependent relaxation, which was associated with increased eNOS and neuronal NOS (nNOS) cavernosal expression.

RESULTS

Cavernosal strips from TNF-alpha KO mice displayed increased endothelium-dependent (97.4 +/- 5.3 vs.

CONTROL

76.3 +/- 6.3, %) and nonadrenergic-noncholinergic (93.3 +/- 3.0 vs.

CONTROL

67.5 +/- 16.0; 16 Hz) relaxation compared to control animals. These responses were associated with increased protein expression of eNOS and nNOS (P < 0.05). Sympathetic-mediated (0.69 +/- 0.16 vs.

CONTROL

1.22 +/- 0.22; 16 Hz) as well as phenylephrine-induced contractile responses (1.6 +/- 0.1 vs.

CONTROL

2.5 +/- 0.1, mN) were attenuated in cavernosal strips from TNF-alpha KO mice. Additionally, corpora cavernosa from TNF-alpha KO mice displayed increased collagen and elastin expression. In vivo experiments demonstrated that TNF-alpha KO mice display increased number of spontaneous erections.

CONCLUSION

Corpora cavernosa from TNF-alpha KO mice display alterations that favor penile tumescence, indicating that TNF-alpha plays a detrimental role in erectile function. A key role for TNF-alpha in mediating endothelial dysfunction in ED is markedly relevant since we now have access to anti-TNF-alpha therapies.