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

The Role of Oxidative Stress and Antioxidants in Cardiovascular Comorbidities in COPD

Oxidative stress driven by several environmental and local airway factors associated with chronic obstructive bronchiolitis, a hallmark feature of COPD, plays a crucial role in disease pathomechanisms. Unbalance between oxidants and antioxidant defense mechanisms amplifies the local inflammatory processes, worsens cardiovascular health, and contributes to COPD-related cardiovascular dysfunctions and mortality. The current review summarizes recent developments in our understanding of different mechanisms contributing to oxidative stress and its countermeasures, with special attention to those that link local and systemic processes. Major regulatory mechanisms orchestrating these pathways are also introduced, with some suggestions for further research in the field.

m6A Modification Mediates Endothelial Cell Responses to Oxidative Stress in Vascular Aging Induced by Low Fluid Shear Stress

N6-methyladenosine (m6A) is one of the most prevalent, abundant, and internal transcriptional modification and plays essential roles in diverse cellular and physiological processes. Low fluid shear stress (FSS) is a key pathological factor for many cardiovascular diseases, which directly forces on the endothelial cells of vessel walls. So far, the alterations and functions of m6A modifications in vascular endothelial cells at the low FSS are still unknown. Herein, we performed the transcriptome-wide m6A modification profiling of HUVECs at different FSS. We found that the m6A modifications were altered earlier and more sensitive than mRNA expressions in response to FSS. The low FSS increased the m6A modifications at CDS region but decreased the m6A modifications at 3' UTR region and regulated both the mRNA expressions and m6A modifications of the m6A regulators, such as the RBM15 and EIF3A. Functional annotations enriched by the hypermethylated and hypomethylated genes at low FSS revealed that the m6A modifications were clustered in the aging-related signaling pathways of mTOR, PI3K-AKT, insulin, and ERRB and in the oxidative stress-related transcriptional factors, such as HIF1A, NFAT5, and NFE2L2. Our study provided a pilot view of m6A modifications in vascular endothelial cells at low FSS and revealed that the m6A modifications driven by low FSS mediated the cellular responses to oxidative stress and cell aging, which suggested that the m6A modifications could be the potential targets for inhibiting vascular aging at pathological low FSS.

Cigarette smoking and erectile dysfunction: an updated review with a focus on pathophysiology, e-cigarettes, and smoking cessation

Introduction

Cigarette smoking has major health implications and causes substantial damage to all organ systems. Approximately one-third of men are active smokers worldwide, and most men are unaware that cigarette smoking can contribute to erectile dysfunction (ED).

Objectives

This article aims to provide a comprehensive overview of research conducted on cigarette smoking and ED, with a particular focus on pathophysiology, electronic cigarettes (e-cigarettes), and smoking cessation.

Methods

A manual literature search was conducted on all research conducted on cigarette smoking and ED up to October 2022.

Results

Substantial evidence is now available showing that past and current cigarette smoking has dose-dependent associations with ED in studies controlling for age and important health comorbidities. Cigarette smoke contains nicotine, carbon monoxide, oxidant chemicals, and metals that can damage the endothelium and disrupt erectile processes. For current smokers, smoking abstinence can strengthen the endothelium and reverse diminished erectile function. The effect of e-cigarettes on endothelial damage and ED remains largely untested. E-cigarettes expose users to fine and ultrafine particles and toxins that can increase risk of cardiovascular injury, but these acute effects appear less potent than conventional cigarettes (long-term cardiovascular effects are still unknown). E-cigarettes are therefore likely to have less harmful effects on ED than conventional cigarettes.

Conclusions

Smoking cessation programs that focus on nicotine replacement therapy (transdermal patches, gum, or inhalers), behavioral counseling, social support, and education programs can be effective approaches to ED treatment in active smokers. Temporarily transferring from regular cigarettes to e-cigarettes—which transmit some of the same carcinogens as conventional cigarettes and are likely to have some long-term cardiovascular effects that disrupt erectile function—might also be useful for long-term smoking cessation and treatment of ED.

Cinnamaldehyde Supplementation Reverts Endothelial Dysfunction in Rat Models of Diet-Induced Obesity: Role of NF-E2-Related Factor-2

Cinnamaldehyde (CN) is an activator of NF-E2-related factor 2 (Nrf2), which has the potential to reduce endothelial dysfunction, oxidative stress and inflammation in metabolic disorders. Our main purpose was to evaluate the effects of CN on vascular dysfunction in metabolic syndrome rats. Normal Wistar (W) rats were divided into eight groups: (1) Wistar (W) rats; (2) W rats fed with a high-fat diet (WHFD); (3) W rats fed with a sucrose diet (WS); (4) WHFD fed with a sucrose diet (WHFDS); (5) W treated with CN (WCn); (6) WS treated with CN (WSCn); (7) WHFD treated with CN (WHFDCn); (8) WHFDS treated with CN (WHFDSCn). CN treatment with 20 mg/kg/day was administered for 8 weeks. Evaluation of metabolic profile, inflammation, endothelial function, oxidative stress, eNOS expression levels and Nrf2 activation was performed. The metabolic dysfunction was greatly exacerbated in the WHFDS rats, accompanied by significantly higher levels of vascular oxidative stress, inflammation, and endothelial dysfunction. In addition, the WHFDS rats displayed significantly reduced activity of Nrf2 at the vascular level. CN significantly reverted endothelial dysfunction in the aortas and the mesenteric arteries. In addition, CN significantly decreased vascular oxidative damage, inflammation at vascular and perivascular level and up-regulated Nrf2 activity in the arteries of WHFDS rats. Cinnamaldehyde, an activator of Nrf2, can be used to improve metabolic profile, and to revert endothelial dysfunction in obesity and metabolic syndrome.

Chronic infusion of ELABELA alleviates vascular remodeling in spontaneously hypertensive rats via anti-inflammatory, anti-oxidative and anti-proliferative effects

Inflammatory activation and oxidative stress promote the proliferation of vascular smooth muscle cells (VSMCs), which accounts for pathological vascular remodeling in hypertension. ELABELA (ELA) is the second endogenous ligand for angiotensin receptor-like 1 (APJ) receptor that has been discovered thus far. In this study, we investigated whether ELA regulated VSMC proliferation and vascular remodeling in spontaneously hypertensive rats (SHRs). We showed that compared to that in Wistar-Kyoto rats (WKYs), ELA expression was markedly decreased in the VSMCs of SHRs. Exogenous ELA-21 significantly inhibited inflammatory cytokines and NADPH oxidase 1 expression, reactive oxygen species production and VSMC proliferation and increased the nuclear translocation of nuclear factor erythroid 2-related factor (Nrf2) in VSMCs. Osmotic minipump infusion of exogenous ELA-21 in SHRs for 4 weeks significantly decreased diastolic blood pressure, alleviated vascular remodeling and ameliorated vascular inflammation and oxidative stress in SHRs. In VSMCs of WKY, angiotensin II (Ang II)-induced inflammatory activation, oxidative stress and VSMC proliferation were attenuated by pretreatment with exogenous ELA-21 but were exacerbated by ELA knockdown. Moreover, ELA-21 inhibited the expression of matrix metalloproteinase 2 and 9 in both SHR-VSMCs and Ang II-treated WKY-VSMCs. We further revealed that exogenous ELA-21-induced inhibition of proliferation and PI3K/Akt signaling were amplified by the PI3K/Akt inhibitor LY294002, while the APJ receptor antagonist F13A abolished ELA-21-induced PI3K/Akt inhibition and Nrf2 activation in VSMCs. In conclusion, we demonstrate that ELA-21 alleviates vascular remodeling through anti-inflammatory, anti-oxidative and anti-proliferative effects in SHRs, indicating that ELA-21 may be a therapeutic agent for treating hypertension.

Galangin Mitigates DOX-induced Cognitive Impairment in Rats: Implication of NOX-1/Nrf-2/HMGB1/TLR4 and TNF-α/MAPKs/RIPK/MLKL/BDNF

The cognitive and behavioral decline observed in cancer survivors who underwent doxorubicin (DOX)-based treatment raises the need for therapeutic interventions to counteract these complications. Galangin (GAL) is a flavonoid-based phytochemical with pronounced protective effects in various neurological disorders. However, its impact on DOX-provoked neurotoxicity has not been clarified. Hence, the current investigation aimed to explore the ability of GAL to ameliorate DOX-provoked chemo-brain in rats. DOX (2mg/kg, once/week, i.p.) and GAL (50mg/kg, 5 times/week., via gavage) were administered for four successive weeks. The MWM and EPM tests were used to evaluate memory disruption and anxiety-like behavior, respectively. Meanwhile, targeted biochemical markers and molecular signals were examined by the aid of ELISA, Western blotting, and immune-histochemistry. In contrast to DOX-impaired rats, GAL effectively preserved hippocampal neurons, improved cognitive/behavioral functions, and enhanced the expression of the cell repair/growth index and BDNF. The antioxidant feature of GAL was confirmed by the amelioration of MDA, NO and NOX-1, along with restoring the Nrf-2/HO-1/GSH cue. In addition, GAL displayed marked anti-inflammatory properties as verified by the suppression of the HMGB1/TLR4 nexus and p-NF-κB p65 to inhibit TNF-α, IL-6, IL-1β, and iNOS. This inhibitory impact extended to entail astrocyte activation, as evidenced by the diminution of GFAP. These beneficial effects were associated with a notable reduction in p-p38^MAPK, p-JNK1/2, and p-ERK1/2, as well as the necroptosis cascade p-RIPK1/p-RIPK3/p-MLKL. Together, these pleiotropic protective impacts advocate the concurrent use of GAL as an adjuvant agent for managing DOX-driven neurodegeneration and cognitive/behavioral deficits. DATA AVAILABILITY: The authors confirm that all relevant data are included in the supplementary materials.

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.

The Interplay Between Mitochondrial Reactive Oxygen Species, Endoplasmic Reticulum Stress, and Nrf2 Signaling in Cardiometabolic Health

Significance: Mitochondria-derived reactive oxygen species (mtROS) are by-products of normal physiology that may disrupt cellular redox homeostasis on a regular basis. Nonetheless, failure to resolve sustained mitochondrial stress to mitigate high levels of mtROS might contribute to the etiology of numerous pathological conditions, such as obesity, insulin resistance, and cardiovascular disease (CVD). Recent Advances: Notably, recent studies have demonstrated that moderate mitochondrial stress might result in the induction of different stress response pathways that ultimately improve the organism's ability to deal with subsequent stress, a process termed mitohormesis. mtROS have been shown to play a key role in regulating this adaptation. Critical Issue: mtROS regulate the convergence of different signaling pathways that, when disturbed, might impair cardiometabolic health. Conversely, mtROS seem to be required to mediate activation of prosurvival pathways, contributing to improved cardiometabolic fitness. In the present review, we will primarily focus on the role of mtROS in the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant pathway and examine the role of endoplasmic reticulum (ER) stress in coordinating the convergence of ER stress and oxidative stress signaling through activation of Nrf2 and activating transcription factor 4 (ATF4). Future Directions: The mechanisms underlying cardiometabolic protection in response to mitochondrial stress have only started to be investigated. Integrated understanding of how mtROS and ER stress cooperatively promote activation of prosurvival pathways might shed mechanistic insight into the role of mitohormesis in mediating cardiometabolic protection and might inform future therapeutic avenues for the treatment of metabolic diseases contributing to CVD. Antioxid. Redox Signal. 35, 252-269.

Melatonin attenuates restenosis after vascular injury in diabetic rats through activation of the Nrf2 signaling pathway

Diabetes is a major risk factor for the development of cardiovascular disease. Diabetic patients have a higher incidence of restenosis following endovascular therapy than non-diabetic patients. Melatonin is primarily synthesized and secreted by the pineal gland and plays an important protective anti-inflammatory and antioxidant role in a variety of cardiovascular diseases. However, no studies to date have evaluated the underlying effects and molecular mechanisms of melatonin on diabetes-related restenosis. Herein, we used an in vivo model of diabetes-related restenosis and an in vitro model of high glucose-cultured vascular smooth muscle cells to investigate the anti-restenosis effect and signaling mechanisms induced by melatonin treatment. The present study provides the first evidence that melatonin attenuates restenosis following vascular injury in diabetic rats. We further investigated the underlying molecular mechanisms both in vivo and in vitro. The data suggest that the Nrf2 signaling pathway is an important molecular target for melatonin-mediated inhibition of diabetes-related restenosis after vascular injury. These findings indicate that melatonin may represent a potential candidate for the prevention or treatment of vascular diseases and restenosis following endovascular therapy, especially in diabetic patients.

Vascular Stress Signaling in Hypertension

Cells respond to stress by activating a variety of defense signaling pathways, including cell survival and cell death pathways. Although cell survival signaling helps the cell to recover from acute insults, cell death or senescence pathways induced by chronic insults can lead to unresolved pathologies. Arterial hypertension results from chronic physiological maladaptation against various stressors represented by abnormal circulating or local neurohormonal factors, mechanical stress, intracellular accumulation of toxic molecules, and dysfunctional organelles. Hypertension and aging share common mechanisms that mediate or prolong chronic cell stress, such as endoplasmic reticulum stress and accumulation of protein aggregates, oxidative stress, metabolic mitochondrial stress, DNA damage, stress-induced senescence, and proinflammatory processes. This review discusses common adaptive signaling mechanisms against these stresses including unfolded protein responses, antioxidant response element signaling, autophagy, mitophagy, and mitochondrial fission/fusion, STING (signaling effector stimulator of interferon genes)-mediated responses, and activation of pattern recognition receptors. The main molecular mechanisms by which the vasculature copes with hypertensive and aging stressors are presented and recent advancements in stress-adaptive signaling mechanisms as well as potential therapeutic targets are discussed.

Hypertension and Erectile Dysfunction: Breaking Down the Challenges

A diagnostic of hypertension increases the risk of erectile dysfunction (ED); likewise, ED can be an early sign of hypertension. In both cases, there is evidence that endothelial dysfunction is a common link between the 2 conditions. During hypertension, the sustained and widespread release of procontractile factors (e.g., angiotensin II, endothelin 1, and aldosterone) impairs the balance between vasoconstrictors and vasodilators and, in turn, detrimentally impacts vascular and erectile structures. This prohypertensive state associates with an enhancement in the generation of reactive oxygen species, which is not compensated by internal antioxidant mechanisms. Recently, the innate immune system, mainly via Toll-like receptor 4, has also been shown to actively contribute to the pathophysiology of hypertension and ED not only by inducing oxidative stress but also by sustaining a low-grade inflammatory state. Furthermore, some drugs used to treat hypertension can cause ED and, consequently, reduce compliance with the prescribed pharmacotherapy. To break down these challenges, in this review, we focus on discussing the well-established as well as the emerging mechanisms linking hypertension and ED with an emphasis on the signaling network of the vasculature and corpora cavernosa, the vascular-like structure of the penis.

The near-infrared dye IR-61 restores erectile function in a streptozotocin-induced diabetes model via mitochondrial protection

This study aimed to evaluate the therapeutic effect of IR-61, a novel mitochondrial heptamethine cyanine dye with antioxidant effects, on diabetes mellitus-induced erectile dysfunction (DMED). Eight-week-old male Sprague-Dawley rats were intraperitoneally injected with streptozotocin (STZ) to induce type 1 diabetes. Eight weeks after STZ injection, all rats were divided into three groups: the control group, DM group, and DM + IR-61 group. In the DM + IR-61 group, the rats were administered IR-61 (1.6 mg kg^-1) twice a week by intravenous injection. At week 13, erectile function was evaluated by determining the ratio of the maximal intracavernous pressure to mean arterial pressure, and the penises were then harvested for fluorescent imaging, transmission electron microscopy, histological examinations, and Western blot analysis. Whole-body imaging suggested that IR-61 was highly accumulated in the penis after intravenous injection. IR-61 treatment significantly improved the maximal ICP of diabetic rats. Additionally, IR-61 ameliorated diabetes-induced inflammation, apoptosis, and phenotypic transition of corpus cavernosum smooth muscle cells (CCSMCs) in penile tissue. IR-61 also attenuated mitochondrial damage, reduced reactive oxygen species production in the corpus cavernosum and upregulated sirtuin1 (SIRT1), sirtuin3 (SIRT3), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), and heme oxygenase expression in penile tissue. In conclusion, IR-61 represents a potential therapeutic option for DMED by protecting the mitochondria of CCSMCs, which may be mediated by activation of the SIRT1, SIRT3, and Nrf2 pathways.

Activation of M3AChR (Type 3 Muscarinic Acetylcholine Receptor) and Nrf2 (Nuclear Factor Erythroid 2-Related Factor 2) Signaling by Choline Alleviates Vascular Smooth Muscle Cell Phenotypic Switching and Vascular Remodeling

OBJECTIVE

Phenotypic switching of vascular smooth muscle cells (VSMCs) plays a critical role in atherosclerosis, vascular restenosis, and hypertension. Choline exerts cardioprotective effects; however, little is known about its effects on VSMC phenotypic switching and vascular remodeling. Here, we investigated whether choline modulates VSMC phenotypic changes and explored the underlying mechanisms. Approach and Results: In cultured VSMCs, choline promoted Nrf2 (nuclear factor erythroid 2-related factor 2) nuclear translocation, inducing the expression of HO-1 (heme oxygenase-1) and NQO-1 (NAD[P]H quinone oxidoreductase-1). Consequently, choline ameliorated Ang II (angiotensin II)-induced increases in NOX (NAD[P]H oxidase) expression and the mitochondrial reactive oxygen species level, thereby attenuating Ang II-induced VSMC phenotypic switching, proliferation, and migration, presumably via M3AChRs (type 3 muscarinic acetylcholine receptors). Downregulation of M3AChR or Nrf2 diminished choline-mediated upregulation of Nrf2, HO-1, and NQO-1 expression, as well as inhibition of VSMC phenotypic transformation, suggesting that M3AChR and Nrf2 activation are responsible for the protective effects of choline. Moreover, activation of the Nrf2 pathway by sulforaphane suppressed Ang II-induced VSMC phenotypic switching and proliferation, indicating that Nrf2 is a key regulator of VSMC phenotypic switching and vascular homeostasis. In a rat model of abdominal aortic constriction in vivo, choline attenuated VSMC phenotypic transformation and vascular remodeling in a manner related to activation of the Nrf2 pathway.

CONCLUSIONS

These results reveal that choline impedes VSMC phenotypic switching, proliferation, migration, and vascular remodeling by activating M3AChR and Nrf2-antioxidant signaling and suggest a novel role for Nrf2 in VSMC phenotypic modulation.

Sulforaphane improves vascular reactivity in mouse and human arteries after "preeclamptic-like" injury

INTRODUCTION

The widespread maternal endothelial dysfunction that underlies the manifestations of preeclampsia is thought to arise from excessive placental production of antiangiogenic factors and enhanced oxidative stress. Therefore, we assessed whether the natural antioxidant sulforaphane could improve vascular function.

METHODS

Cell viability of human umbilical vein endothelial cells (HUVECs) was assessed after 24 or 48 h in normoxia (20% O₂) or hypoxia (1% O₂) with or without sulforaphane. To model vascular dysfunction associated with preeclampsia, mouse mesenteric arteries were incubated in trophoblast conditioned media (TCM), and human omental arteries incubated in preeclamptic explant media (PEM) with or without sulforaphane. Both media are rich in antiangiogenic compounds associated with preeclampsia. TCM was generated from primary cytotrophoblast cells from term placentae of normotensive, while PEM was generated from explants from preeclamptic women. Reactivity was assessed by wire myography. sulforaphane's actions as a vasodilator were also investigated.

RESULTS

Under conditions of hypoxia, sulforaphane improved HUVEC viability. In mouse mesenteric arteries, sulforaphane reduced contraction evoked by potassium (p < 0.001), phenylephrine and endothelin 1 (all p < 0.001). Sulforaphane also inhibited Ca²⁺-induced contraction (p = 0.014). Sulforaphane prevented TCM-induced augmentation of phenylephrine and angiotensin II-mediated contraction of mouse mesenteric arteries. In human omental arteries, sulforaphane induced vasodilation (p < 0.001), and prevented PEM-induced endothelial dysfunction by restoring arterial sensitivity to the endothelium-dependent vasodilator bradykinin (p = 0.008).

DISCUSSION

Sulforaphane causes relaxation in arteries and protects against arterial dysfunction induced by placental-derived antiangiogenic factors, which are known to contribute to the preeclampsia.

A Systematic Review on Rho-Kinase as a Potential Therapeutic Target for the Treatment of Erectile Dysfunction

Background

Erectile dysfunction (ED) is a common clinical condition with limited treatment options. The main aim of the present systematic review was to synthesize information on Rho-kinase as a novel therapeutic approach for the treatment of ED.

Methods

We performed a systematic literature study in PubMed, Google Scholar and Scopus. Included studies were original articles studied the role of Rho-kinase in the pathogenesis and/or new treatment approach for ED in animal models and clinical studies, published between 2014 and 2019. Data derived from each study were study design used, interventions applied and main treatment outcomes. The quality of the selected articles was assessed by CAMARADES criteria and data were analyzed using descriptive statistics.

Results

A total of 1067 original articles were retrieved in the given period and eighteen papers met our inclusion criteria. Five articles explain the role of Rho-kinase in ED pathogenesis using different models such as cavernous nerve crush injury, heart failure-induced ED, vasculogenic and post-radical prostatectomy ED, diabetes-induced ED and age-related ED. Other ten papers explain the role of novel drugs evaluated for ED treatment by targeting Rho-kinase as a new approach for ED therapy. The rest three papers discuss the role of plant extracts used by traditional society for the treatment of ED and assess their potential function in targeting Rho-kinase in animal models. The penile erectile functional index has shown that the ratio of intracavernosal pressure to mean arterial pressure (ICP/MAP) was decreased due to age and various chronic diseases. Whilst, ROCK I and ROCK II expression were increased. Western blot findings have also shown that ROCK II and MYPT-1 phosphorylation rates increased in cavernous tissue after ED induction. Besides, compounds which can inhibit the action of Rho-kinase activity showed relaxation of the corpus cavernosum, decrease in corporal fibrosis, and alleviate increased apoptosis and caspase-3 activity in an NO-independent manner. Moreover, histological and molecular dysregulation have been improved by inhibition of Rho-kinase.

Conclusion

Targeting Rho-kinase may be a possible target for the treatment of ED secondary to specific causes, and Rho-kinase inhibitors may be a new drug family for the treatment of ED. However, this requires further studies for in-depth understanding.

Baicalein Alleviates Erectile Dysfunction Associated With Streptozotocin-Induced Type I Diabetes by Ameliorating Endothelial Nitric Oxide Synthase Dysfunction, Inhibiting Oxidative Stress and Fibrosis

BACKGROUND

Management of diabetes mellitus induced-erectile dysfunction (DMED) is challenging because of its poor responses to phosphodiesterase type 5 inhibitors. Increasingly important roles of 12-lipoxygenase (12-LOX) have been proven in diabetes mellitus.

AIM

To investigate 12-LOX activity and therapeutic effect of its inhibitor, baicalein (BE), on DMED.

METHODS

Intraperitoneal streptozotocin injection was used to induce type I DM, and an apomorphine test was used to evaluate erectile function. In experiment A, we assessed 12-LOX expression alteration in the corpus cavernosum (CC) of rats with DMED of different levels of severity. In experiment B, rats with DMED were intraperitoneally injected with BE for 4 weeks, and control rats were injected with vehicles. The erectile function was tested by cavernous nerve stimulation before penile tissue was harvested. We performed Western blot, immunohistochemistry, immunofluorescence, Masson trichrome staining, and enzyme-linked immunosorbent assays to measure related proteins in CC.

MAIN OUTCOME MEASURE

The main outcome measures included rectile response, histologic examination, and expression alteration of related proteins.

RESULTS

12-LOX upregulation was associated with the progression of type I DMED. After 4 weeks treatment, compared with the DMED group, the DMED + BE group showed better erectile responses to cavernous nerve stimulation. In the DMED + BE group, significantly enhanced endothelial nitric oxide synthase/nitric oxide/cyclic guanosine monophosphate pathway, reduced 12-LOX expression, and inhibited p38 mitogen-activated protein kinase/arginase II/L-arginine pathway were showed in CC relative to the DMED group. In addition, overactivated oxidative stress and fibrosis in the DMED group were both partially ameliorated in the DMED + BE group.

CLINICAL IMPLICATIONS

BE may be considered as an effective therapy for DMED, but needs to be verified in future human investigations.

STRENGTHS & LIMITATIONS

The role of 12-LOX and its inhibitor, BE, is firstly demonstrated in rats with type I DMED. However, the experimental data are derived from animal models with without evidences from cellular-based experiments.

CONCLUSION

12-LOX might serve as an important factor in the pathogenesis of type I DMED. BE alleviated erectile dysfunction in rats with type I DMED probably by inhibiting 12-LOX expression, ameliorating endothelial nitric oxide synthase dysfunction, as well as suppressing oxidative stress and fibrosis. Chen Y, Zhou B, Yu Z, et al. Baicalein Alleviates Erectile Dysfunction Associated With Streptozotocin-Induced Type I Diabetes by Ameliorating Endothelial Nitric Oxide Synthase Dysfunction, Inhibiting Oxidative Stress and Fibrosis. J Sex Med 2020;17:1434-1447.

ER stress and Rho kinase activation underlie the vasculopathy of CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) leads to premature stroke and vascular dementia. Mechanism-specific therapies for this aggressive cerebral small vessel disease are lacking. CADASIL is caused by NOTCH3 mutations that influence vascular smooth muscle cell (VSMC) function through unknown processes. We investigated molecular mechanisms underlying the vasculopathy in CADASIL focusing on endoplasmic reticulum (ER) stress and RhoA/Rho kinase (ROCK). Peripheral small arteries and VSMCs were isolated from gluteal biopsies of CADASIL patients and mesentery of TgNotch3R169C mice (CADASIL model). CADASIL vessels exhibited impaired vasorelaxation, blunted vasoconstriction, and hypertrophic remodeling. Expression of NOTCH3 and ER stress target genes was amplified and ER stress response, Rho kinase activity, superoxide production, and cytoskeleton-associated protein phosphorylation were increased in CADASIL, processes associated with Nox5 upregulation. Aberrant vascular responses and signaling in CADASIL were ameliorated by inhibitors of Notch3 (γ-secretase inhibitor), Nox5 (mellitin), ER stress (4-phenylbutyric acid), and ROCK (fasudil). Observations in human CADASIL were recapitulated in TgNotch3R169C mice. These findings indicate that vascular dysfunction in CADASIL involves ER stress/ROCK interplay driven by Notch3-induced Nox5 activation and that NOTCH3 mutation-associated vascular pathology, typical in cerebral vessels, also manifests peripherally. We define Notch3-Nox5/ER stress/ROCK signaling as a putative mechanism-specific target and suggest that peripheral artery responses may be an accessible biomarker in CADASIL.

The Role of NADPH Oxidases in the Etiology of Obesity and Metabolic Syndrome: Contribution of Individual Isoforms and Cell Biology

Significance: Highly prevalent in Western cultures, obesity, metabolic syndrome, and diabetes increase the risk of cardiovascular morbidity and mortality and cost health care systems billions of dollars annually. At the cellular level, obesity, metabolic syndrome, and diabetes are associated with increased production of reactive oxygen species (ROS). Increased levels of ROS production in key organ systems such as adipose tissue, skeletal muscle, and the vasculature cause disruption of tissue homeostasis, leading to increased morbidity and risk of mortality. More specifically, growing evidence implicates the nicotinamide adenine dinucleotide phosphate oxidase (NOX) enzymes in these pathologies through impairment of insulin signaling, inflammation, and vascular dysfunction. The NOX family of enzymes is a major driver of redox signaling through its production of superoxide anion, hydrogen peroxide, and attendant downstream metabolites acting on redox-sensitive signaling molecules. Recent Advances: The primary goal of this review is to highlight recent advances and survey our present understanding of cell-specific NOX enzyme contributions to metabolic diseases. Critical Issues: However, due to the short half-lives of individual ROS and/or cellular defense systems, radii of ROS diffusion are commonly short, often restricting redox signaling and oxidant stress to localized events. Thus, special emphasis should be placed on cell type and subcellular location of NOX enzymes to better understand their role in the pathophysiology of metabolic diseases. Future Directions: We discuss the targeting of NOX enzymes as potential therapy and bring to light potential emerging areas of NOX research, microparticles and epigenetics, in the context of metabolic disease.

Impact of Immune System Activation and Vascular Impairment on Male and Female Sexual Dysfunction

INTRODUCTION

Male and female sexual dysfunction (SD) is considered a multifactorial condition. Numerous studies have shown the involvement of inflammatory processes in this pathological condition. Sexual intercourse requires healthy and functioning vessels to supply the pelvic region in both males and females, generating penile erection and clitoral and vaginal lubrication, respectively. Cardiovascular diseases and associated risk factors may contribute negatively to pelvic blood flow, possibly through immune system activation.

AIM

The study aimed to address the correlation between vascular inflammation driven by immune system activation and SD in males and females.

METHODS

A literature review was performed to identify articles addressing male and female SD and vascular inflammation. Key words included "male and female sexual dysfunction," "vascular inflammation," "iliac and pudendal arteries dysfunction," "genitourinary tract," and "blood flow."

MAIN OUTCOME MEASURES

Management of systemic and local inflammation may be a useful alternative to improve SD and reduce the risk of cardiovascular diseases in the future.

RESULTS

Increased levels of cytokines and chemokines have been detected in humans and animals with hypertension, obesity, and diabetic conditions. Chronic activation of the innate immune system, especially by pathogen- or damage-associated molecular patterns, and metabolic-related disorders may act as triggers further contributing to an increased inflammatory condition. Due to the reduced size of vessels, SD and retinal vascular impairments have been shown to be predictive factors for cardiovascular diseases. Therefore, considering that blood flow to the genitalia is essential for sexual function, endothelial dysfunction and vascular remodeling, secondary to chronic immune system activation, may be implicated in male and female vasculogenic SD.

CONCLUSIONS

Several conditions appear to play a role in SD. In the present review, we have identified a role for the immune system in generating vascular and tissue impairments contributing to erectile dysfunction and female SD. Calmasini FB, Klee N, Webb RC, et al. Impact of Immune System Activation and Vascular Impairment on Male and Female Sexual Dysfunction. Sex Med Rev 2019;7:604-613.

Short-term pharmacological activation of Nrf2 ameliorates vascular dysfunction in aged rats and in pathological human vasculature. A potential target for therapeutic intervention

Oxidative stress contributes to endothelial dysfunction, a key step in cardiovascular disease development. Ageing-related vascular dysfunction involves defective antioxidant response. Nuclear factor erythroid 2-like-2 (Nrf2), orchestrates cellular response to oxidative stress. We evaluated the impact of Nrf2-activation on endothelium-dependent and H₂O₂-mediated vasodilations in: aorta (RA), mesenteric artery (RMA), coronary artery (RCA) and corpus cavernosum (RCC) from ageing rats and in human penile arteries (HPRA) and corpus cavernosum (HCC) from erectile dysfunction (ED) patients. Relaxant responses were evaluated in organ chambers and wire myographs. Nrf2 content and heme oxygenase-1 (HO-1) were determined by ELISA. Superoxide and Nrf2 were detected by immunofluorescence. Pharmacological activation of Nrf2 with sulforaphane (SFN) improved NO- and endothelium-derived hyperpolarizing factor-mediated endothelium-dependent vasodilation and H₂O₂-induced relaxation in vascular beds from aging rats. SFN-induced effects were associated with increased Nrf2 (RMA, RCA) and reduced superoxide detection in RCA. Improvement of vascular function was confirmed in HPRA and HCC from ED patients and mimicked by another Nrf2 activator, oltipraz. Nrf2 increase and superoxide reduction together with HO-1 increase by Nrf2 activation was evidenced in HCC from ED patients. PDE5 inhibitor-induced relaxations of HPRA and HCC from ED patients were enhanced by SFN. Nrf2 short-term pharmacological activation attenuates age-related impairment of endothelium-dependent and reactive oxygen species (ROS)-induced vasodilation in different rat and human vascular territories by upregulation of Nrf2-related signaling and decreased oxidative stress. In ED patients target tissues, Nrf2 potentiates the functional effect of ED conventional pharmacological therapy suggesting potential therapeutic implication.

Nrf2 as a Potential Mediator of Cardiovascular Risk in Metabolic Diseases

Free radicals act as secondary messengers, modulating a number of important biological processes, including gene expression, ion mobilization in transport systems, protein interactions and enzymatic functions, cell growth, cell cycle, redox homeostasis, among others. In the cardiovascular system, the physiological generation of free radicals ensures the integrity and function of cardiomyocytes, endothelial cells, and adjacent smooth muscle cells. In physiological conditions, there is a balance between free radicals generation and the activity of enzymatic and non-enzymatic antioxidant systems. Redox imbalance, caused by increased free radical's production and/or reduced antioxidant defense, plays an important role in the development of cardiovascular diseases, contributing to cardiac hypertrophy and heart failure, endothelial dysfunction, hypertrophy and hypercontractility of vascular smooth muscle. Excessive production of oxidizing agents in detriment of antioxidant defenses in the cardiovascular system has been described in obesity, diabetes mellitus, hypertension, and atherosclerosis. The transcription factor Nrf2 (nuclear factor erythroid 2-related factor 2), a major regulator of antioxidant and cellular protective genes, is primarily activated in response to oxidative stress. Under physiological conditions, Nrf2 is constitutively expressed in the cytoplasm of cells and is usually associated with Keap-1, a repressor protein. This association maintains low levels of free Nrf2. Stressors, such as free radicals, favor the translocation of Nrf2 to the cell nucleus. The accumulation of nuclear Nrf2 allows the binding of this protein to the antioxidant response element of genes that code antioxidant proteins. Although little information on the role of Nrf2 in the cardiovascular system is available, growing evidence indicates that decreased Nrf2 activity contributes to oxidative stress, favoring the pathophysiology of cardiovascular disorders found in obesity, diabetes mellitus, and atherosclerosis. The present mini-review will provide a comprehensive overview of the role of Nrf2 as a contributing factor to cardiovascular risk in metabolic diseases.

Upregulation of Nrf2 and Decreased Redox Signaling Contribute to Renoprotective Effects of Chemerin Receptor Blockade in Diabetic Mice

Chemerin, acting through its receptor ChemR23, is an adipokine associated with inflammatory response, glucose and lipid metabolism and vascular function. Although this adipokine has been associated with the development and progression of kidney disease, it is not clear whether the chemerin/ChemR23 system plays a role in renal function in the context of diabetes. Therefore, we sought to determine whether ChemR23 receptor blockade prevents the development and/or progression of diabetic nephropathy and questioned the role of oxidative stress and Nrf2 in this process. Renal redox state and function were assessed in non-diabetic lean db/m and diabetic obese db/db mice treated with vehicle or CCX832 (ChemR23 antagonist). Renal reactive oxygen species (ROS) production, which was increased in diabetic mice, was attenuated by CCX832. This was associated with an increase in Nox 4 expression. Augmented protein oxidation in db/db mice was not observed when mice were treated with CCX832. CCX832 also abrogated impaired Nrf2 nuclear activity and associated downregulation in antioxidants expression in kidneys from db/db mice. Our in vivo findings highlight the role of the redox signaling and Nrf2 system as renoprotective players during chemerin receptor blockade in diabetic mice. The chemerin/ChemR23 system may be an important target to limit renal dysfunction associated with obesity-related diabetes.

Vascular Nox (NADPH Oxidase) Compartmentalization, Protein Hyperoxidation, and Endoplasmic Reticulum Stress Response in Hypertension

Vascular Nox (NADPH oxidase)-derived reactive oxygen species and endoplasmic reticulum (ER) stress have been implicated in hypertension. However, relationships between these processes are unclear. We hypothesized that Nox isoforms localize in a subcellular compartment-specific manner, contributing to oxidative and ER stress, which influence the oxidative proteome and vascular function in hypertension. Nox compartmentalization (cell fractionation), O₂^- (lucigenin), H₂O₂ (amplex red), reversible protein oxidation (sulfenylation), irreversible protein oxidation (protein tyrosine phosphatase, peroxiredoxin oxidation), and ER stress (PERK [protein kinase RNA-like endoplasmic reticulum kinase], IRE1α [inositol-requiring enzyme 1], and phosphorylation/oxidation) were studied in spontaneously hypertensive rat (SHR) vascular smooth muscle cells (VSMCs). VSMC proliferation was measured by fluorescence-activated cell sorting, and vascular reactivity assessed in stroke-prone SHR arteries by myography. Noxs were downregulated by short interfering RNA and pharmacologically. In SHR, Noxs were localized in specific subcellular regions: Nox1 in plasma membrane and Nox4 in ER. In SHR, oxidative stress was associated with increased protein sulfenylation and hyperoxidation of protein tyrosine phosphatases and peroxiredoxins. Inhibition of Nox1 (NoxA1ds), Nox1/4 (GKT137831), and ER stress (4-phenylbutyric acid/tauroursodeoxycholic acid) normalized SHR vascular reactive oxygen species generation. GKT137831 reduced IRE1α sulfenylation and XBP1 (X-box binding protein 1) splicing in SHR. Increased VSMC proliferation in SHR was normalized by GKT137831, 4-phenylbutyric acid, and STF083010 (IRE1-XBP1 disruptor). Hypercontractility in the stroke-prone SHR was attenuated by 4-phenylbutyric acid. We demonstrate that protein hyperoxidation in hypertension is associated with oxidative and ER stress through upregulation of plasmalemmal-Nox1 and ER-Nox4. The IRE1-XBP1 pathway of the ER stress response is regulated by Nox4/reactive oxygen species and plays a role in the hyperproliferative VSMC phenotype in SHR. Our study highlights the importance of Nox subcellular compartmentalization and interplay between cytoplasmic reactive oxygen species and ER stress response, which contribute to the VSMC oxidative proteome and vascular dysfunction in hypertension.

Increased O-GlcNAcylation of Endothelial Nitric Oxide Synthase Compromises the Anti-contractile Properties of Perivascular Adipose Tissue in Metabolic Syndrome

Under physiological conditions, the perivascular adipose tissue (PVAT) negatively modulates vascular contractility. This property is lost in experimental and human obesity and in the metabolic syndrome, indicating that changes in PVAT function may contribute to vascular dysfunction associated with increased body weight and hyperglycemia. The O-linked β-N-acetylglucosamine (O-GlcNAc) modification of proteins (O-GlcNAcylation) is a unique posttranslational process that integrates glucose metabolism with intracellular protein activity. Increased flux of glucose through the hexosamine biosynthetic pathway and the consequent increase in tissue-specific O-GlcNAc modification of proteins have been linked to multiple facets of vascular dysfunction in diabetes and other pathological conditions. We hypothesized that chronic consumption of glucose, a condition that progresses to metabolic syndrome, leads to increased O-GlcNAc modification of proteins in the PVAT, decreasing its anti-contractile effects. Therefore, the current study was devised to determine whether a high-sugar diet increases O-GlcNAcylation in the PVAT and how increased O-GlcNAc interferes with PVAT vasorelaxant function. To assess molecular mechanisms by which O-GlcNAc contributes to PVAT dysfunction, thoracic aortas surrounded by PVAT were isolated from Wistar rats fed either a control or high sugar diet, for 10 and 12 weeks. Rats chronically fed a high sugar diet exhibited metabolic syndrome features, increased O-GlcNAcylated-proteins in the PVAT and loss of PVAT anti-contractile effect. PVAT from high sugar diet-fed rats for 12 weeks exhibited decreased NO formation, reduced expression of endothelial nitric oxide synthase (eNOS) and increased O-GlcNAcylation of eNOS. High sugar diet also decreased OGA activity and increased superoxide anion generation in the PVAT. Visceral adipose tissue samples from hyperglycemic patients showed increased levels of O-GlcNAc-modified proteins, increased ROS generation and decreased OGA activity. These data indicate that O-GlcNAcylation contributes to metabolic syndrome-induced PVAT dysfunction and that O-GlcNAcylation of eNOS may be targeted in the development of novel therapies for vascular dysfunction in conditions associated with hyperglycemia.

The Sulforaphane and pyridoxamine supplementation normalize endothelial dysfunction associated with type 2 diabetes

In this study we investigate pyridoxamine (PM) and/or sulforaphane (SFN) as therapeutic interventions to determine whether activators of NFE2-related factor 2 (Nrf2) can be used in addition with inhibitors of advanced glycation end products (AGE) formation to attenuate oxidative stress and improve endothelial dysfunction in type 2 diabetes. Goto-kakizaki (GK) rats, an animal model of non-obese type 2 diabetes, were treated with or without PM and/or SFN during 8 weeks and compared with age-matched Wistar rats. At the end of the treatment, nitric oxide (NO)-dependent and independent vasorelaxation in isolated aorta and mesenteric arteries were evaluated. Metabolic profile, NO bioavailability and vascular oxidative stress, AGE and Nrf2 levels were also assessed. Diabetic GK rats presented significantly lower levels of Nrf2 and concomitantly exhibited higher levels of oxidative stress and endothelial dysfunction. PM and SFN as monotherapy were capable of significantly improving endothelial dysfunction in aorta and mesenteric arteries decreasing vascular oxidative damage, AGE and HbA1c levels. Furthermore, SFN + PM proved more effective reducing systemic free fatty acids levels, normalizing endothelial function, NO bioavailability and glycation in GK rats. Activators of Nrf2 can be used therapeutically in association with inhibitors of AGE and cross-linking formation to normalize endothelial dysfunction in type 2 diabetes.

Macro- and microvascular endothelial dysfunction in diabetes

Endothelial cells, as well as their major products nitric oxide (NO) and prostacyclin, play a key role in the regulation of vascular homeostasis. Diabetes mellitus is an important risk factor for cardiovascular disease. Diabetes-induced endothelial dysfunction is a critical and initiating factor in the genesis of diabetic vascular complications. The present review focuses on both large blood vessels and the microvasculature. The endothelial dysfunction in diabetic macrovascular complications is characterized by reduced NO bioavailability, poorly compensated for by increased production of prostacyclin and/or endothelium-dependent hyperpolarizations, and increased production or action of endothelium-derived vasoconstrictors. The endothelial dysfunction of microvascular complications is primarily characterized by decreased release of NO, enhanced oxidative stress, increased production of inflammatory factors, abnormal angiogenesis, and impaired endothelial repair. In addition, non-coding RNAs (microRNAs) have emerged as participating in numerous cellular processes. Thus, this reviews pays special attention to microRNAs and their modulatory role in diabetes-induced vascular dysfunction. Some therapeutic strategies for preventing and restoring diabetic endothelial dysfunction are also highlighted.

Targeting the NF-E2-Related Factor 2 Pathway: a Novel Strategy for Traumatic Brain Injury

As an essential component of cellular defense against a variety of endogenous and exogenous stresses, nuclear factor erythroid 2-related factor 2 (Nrf2) has received increased attention in the past decades. Multiple studies indicate that Nrf2 acts not only as an important protective factor in injury models but also as a downstream target of therapeutic agents. Activation of Nrf2 has increasingly been linked to many human diseases, especially in central nervous system (CNS) injury such as traumatic brain injury (TBI). Several researches have deciphered that activation of Nrf2 exerts antioxidative stress, antiapoptosis, and antiinflammation influence in TBI via different molecules and pathways including heme oxygenase-1 (HO-1), NADPH:quinine oxidoreductase-1 (NQO-1), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2). Hence, Nrf2 shows great promise as a molecular target in TBI. In the present article, we provide an updated review of the current state of our knowledge about relationship between Nrf2 and TBI, highlighting the specific roles of Nrf2 in TBI.