Reactive oxygen species signaling in vascular smooth muscle cells

The interplay of ferroptosis and oxidative stress in the pathogenesis of aortic dissection

Aortic dissection (AD) is a life-threatening vascular condition marked by the separation or tearing of the aortic media. Ferroptosis, a form of iron-dependent programmed cell death, occurs alongside lipid peroxidation and the accumulation of reactive oxygen species (ROS). The relationship between ferroptosis and AD lies in its damaging effect on vascular cells. In AD, ferroptosis worsens the damage to vascular smooth muscle cells (VSMCs) and endothelial cells (ECs), thereby weakening the vascular wall's structural integrity and accelerating the onset and progression of the condition. However, the molecular mechanisms through which ferroptosis regulates the onset and progression of AD remain poorly understood. This article explores the relationship between ferroptosis and AD.

Mechanical Activation of cPLA2 Impedes Fatty Acid β-Oxidation in Vein Grafts

High-magnitude cyclic stretch from arterial blood pressure significantly contributes to the excessive proliferation and migration of vascular smooth muscle cells (VSMCs), leading to neointima formation in vein grafts. However, the molecular mechanisms remain unclear. This study highlights the critical role of cytosolic Phospholipase A2 (cPLA2)/ Yin Yang 1 (YY1)/ carnitine palmitoyltransferase 1b (CPT1B) signaling in coordinating VSMC mechanical activation by inhibiting fatty acid β-oxidation. Metabolomic analysis showed that a 15%-1 Hz arterial cyclic stretch, compared to a 5%-1 Hz venous stretch, increased long-chain fatty acids in VSMCs. cPLA2, identified as a mechanoresponsive molecule, produces excessive arachidonic acid (ArAc) under the 15%-1 Hz stretch, inhibiting CPT1B expression, a key enzyme in fatty acid β-oxidation. ArAc promotes transcription factor YY1 degradation, downregulating CPT1B. Inadequate fatty acid oxidation caused by knockdown of CPT1B or YY1, or etomoxir treatment, increased nuclear membrane tension, orchestrating the activation of cPLA2. Overexpressing CPT1B or inhibiting cPLA2 reduced VSMC proliferation and migration in vein grafts, decreasing neointimal hyperplasia. This study uncovers a novel mechanism in lipid metabolic reprogramming in vein grafts, suggesting a new therapeutic target for vein graft hyperplasia.

Impact of Ionizing Radiation Exposure on Placental Function and Implications for Fetal Programming

Accidental exposure to high-dose radiation while pregnant has shown significant negative effects on the developing fetus. One fetal organ which has been studied is the placenta. The placenta performs all essential functions for fetal development, including nutrition, respiration, waste excretion, endocrine communication, and immunological functions. Improper placental development can lead to complications during pregnancy, as well as the occurrence of intrauterine growth-restricted (IUGR) offspring. IUGR is one of the leading indicators of fetal programming, classified as an improper uterine environment leading to the predisposition of diseases within the offspring. With numerous studies examining fetal programming, there remains a significant gap in understanding the placenta's role in irradiation-induced fetal programming. This review aims to synthesize current knowledge on how irradiation affects placental function to guide future research directions. This review provides a comprehensive overview of placental biology, including its development, structure, and function, and summarizes the placenta's role in fetal programming, with a focus on the impact of radiation on placental biology. Taken together, this review demonstrates that fetal radiation exposure causes placental degradation and immune function dysregulation. Given the placenta's crucial role in fetal development, understanding its impact on irradiation-induced IUGR is essential.

The relationship of redox signaling with the risk for atherosclerosis

Oxidative balance plays a pivotal role in physiological homeostasis, and many diseases, particularly age-related conditions, are closely associated with oxidative imbalance. While the strategic role of oxidative regulation in various diseases is well-established, the specific involvement of oxidative stress in atherosclerosis remains elusive. Atherosclerosis is a chronic inflammatory disorder characterized by plaque formation within the arteries. Alterations in the oxidative status of vascular tissues are linked to the onset, progression, and outcome of atherosclerosis. This review examines the role of redox signaling in atherosclerosis, including its impact on risk factors such as dyslipidemia, hyperglycemia, inflammation, and unhealthy lifestyle, along with dysregulation, vascular homeostasis, immune system interaction, and therapeutic considerations. Understanding redox signal transduction and the regulation of redox signaling will offer valuable insights into the pathogenesis of atherosclerosis and guide the development of novel therapeutic strategies.

Exploring the pathogenesis of pulmonary vascular disease

Pulmonary hypertension (PH) is a complex cardiopulmonary disorder impacting the lung vasculature, resulting in increased pulmonary vascular resistance that leads to right ventricular dysfunction. Pulmonary hypertension comprises of 5 groups (PH group 1 to 5) where group 1 pulmonary arterial hypertension (PAH), results from alterations that directly affect the pulmonary arteries. Although PAH has a complex pathophysiology that is not completely understood, it is known to be a multifactorial disease that results from a combination of genetic, epigenetic and environmental factors, leading to a varied range of symptoms in PAH patients. PAH does not have a cure, its incidence and prevalence continue to increase every year, resulting in higher morbidity and mortality rates. In this review, we discuss the different pathologic mechanisms with a focus on epigenetic modifications and their roles in the development and progression of PAH. These modifications include DNA methylation, histone modifications, and microRNA dysregulation. Understanding these epigenetic modifications will improve our understanding of PAH and unveil novel therapeutic targets, thus steering research toward innovative treatment strategies.

Antioxidant Systems of Plant Pathogenic Fungi: Functions in Oxidative Stress Response and Their Regulatory Mechanisms

During the infection process, plant pathogenic fungi encounter plant-derived oxidative stress, and an appropriate response to this stress is crucial to their survival and establishment of the disease. Plant pathogenic fungi have evolved several mechanisms to eliminate oxidants from the external environment and maintain cellular redox homeostasis. When oxidative stress is perceived, various signaling transduction pathways are triggered and activate the downstream genes responsible for the oxidative stress response. Despite extensive research on antioxidant systems and their regulatory mechanisms in plant pathogenic fungi, the specific functions of individual antioxidants and their impacts on pathogenicity have not recently been systematically summarized. Therefore, our objective is to consolidate previous research on the antioxidant systems of plant pathogenic fungi. In this review, we explore the plant immune responses during fungal infection, with a focus on the generation and function of reactive oxygen species. Furthermore, we delve into the three antioxidant systems, summarizing their functions and regulatory mechanisms involved in oxidative stress response. This comprehensive review provides an integrated overview of the antioxidant mechanisms within plant pathogenic fungi, revealing how the oxidative stress response contributes to their pathogenicity.

Proteasome inhibitor bortezomib prevents proliferation and migration of pulmonary arterial smooth muscle cells

Pulmonary vascular remodeling is a key pathological process of pulmonary arterial hypertension (PAH), characterized by uncontrolled proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs). Bortezomib (BTZ) is the first Food and Drug Administration (FDA)-approved proteasome inhibitor for multiple myeloma treatment. Recently, there is emerging evidence showing its effect on reversing PAH, although its mechanisms are not well understood. In this study, anti-proliferative and anti-migratory effects of BTZ on PASMCs were first examined by different inducers such as fetal bovine serum (FBS), angiotensin II (Ang II) and platelet-derived growth factor (PDGF)-BB, while potential mechanisms including cellular reactive oxygen species (ROS) and mitochondrial ROS were then investigated; finally, signal transduction of ERK and Akt was examined. Our results showed that BTZ attenuated FBS-, Ang II- and PDGF-BB-induced proliferation and migration, with associated decreased cellular ROS production and mitochondrial ROS production. In addition, the phosphorylation of ERK and Akt induced by Ang II and PDGF-BB was also inhibited by BTZ treatment. This study indicates that BTZ can prevent proliferation and migration of PASMCs, which are possibly mediated by decreased ROS production and down-regulation of ERK and Akt. Thus, proteasome inhibition can be a novel pharmacological target in the management of PAH.

Alginate oligosaccharide alleviates vascular aging by upregulating glutathione peroxidase 7

Alginate oligosaccharide (AOS) may delay aging by decreasing oxidative stress, but the effects on vascular aging remain unclear. Here, we evaluate the effect of AOS on vascular aging and investigate the underlying mechanisms. Twenty-month-old rats acted as the natural aging model in vivo. Senescence of human aortic vascular smooth muscle cells (HA-VSMCs) was induced in vitro using angiotensin II (AngII). The aging rats and senescent cells were treated with AOS, followed by assessment of aging makers, oxidative stress, and aging-induced vascular remodeling. AOS treatment alleviated vascular aging and HA-VSMC senescence and decreased the levels of oxidative stress and vascular remodeling-associated indicators. AOS upregulated the expression of glutathione peroxidase 7 (GPX7) in aging rats and GPX7 depletion disrupted the geroprotective effect of AOS. AOS increased the nuclear translocation of nuclear factor erythroid-2-related factor (Nrf2) protein, which interacts with GPX7 protein to induce its expression. In conclusion, AOS alleviates vascular aging and HA-VSMC senescence and reduces aging-related vascular remodeling via the GPX7 antioxidant pathway, which may provide new avenues for treating aging-associated diseases.

Significance of the Wnt signaling pathway in coronary artery atherosclerosis

Introduction

The progression of coronary atherosclerosis is an active and regulated process. The Wnt signaling pathway is thought to play an active role in the pathogenesis of several cardiovascular diseases; however, a better understanding of this system in atherosclerosis is yet to be unraveled.

Methods

In this study, real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and Western blotting were used to quantify the expression of Wnt3a, Wnt5a, and Wnt5b in the human coronary plaque, and immunohistochemistry was used to identify sites of local expression. To determine the pathologic significance of increased Wnt, human vascular smooth muscle cells (vSMCs) were treated with Wnt3a, Wnt5a, and Wnt5b recombinant proteins and assessed for changes in cell differentiation and function.

Results

RT-PCR and Western blotting showed a significant increase in the expression of Wnt3a, Wnt5a, Wnt5b, and their receptors in diseased coronary arteries compared with that in non-diseased coronary arteries. Immunohistochemistry revealed an abundant expression of Wnt3a and Wnt5b in diseased coronary arteries, which contrasted with little or no signals in normal coronary arteries. Immunostaining of Wnt3a and Wnt5b was found largely in inflammatory cells and myointimal cells. The treatment of vSMCs with Wnt3a, Wnt5a, and Wnt5b resulted in increased vSMC differentiation, migration, calcification, oxidative stress, and impaired cholesterol handling.

Conclusions

This study demonstrates the upregulation of three important members of canonical and non-canonical Wnt signaling pathways and their receptors in coronary atherosclerosis and shows an important role for these molecules in plaque development through increased cellular remodeling and impaired cholesterol handling.

Effect of reactive oxygen, nitrogen, and sulfur species on signaling pathways in atherosclerosis

Atherosclerosis is a chronic inflammatory disease in which fats, lipids, cholesterol, calcium, proliferating smooth muscle cells, and immune cells accumulate in the intima of the large arteries, forming atherosclerotic plaques. A complex interplay of various vascular and immune cells takes place during the initiation and progression of atherosclerosis. Multiple reports indicate that tight control of reactive oxygen species (ROS), reactive nitrogen species (RNS), and reactive sulfur species (RSS) production is critical for maintaining vascular health. Unrestricted ROS and RNS generation may lead to activation of various inflammatory signaling pathways, facilitating atherosclerosis. Given these deleterious consequences, it is important to understand how ROS and RNS affect the signaling processes involved in atherogenesis. Conversely, RSS appears to exhibit an atheroprotective potential and can alleviate the deleterious effects of ROS and RNS. Herein, we review the literature describing the effects of ROS, RNS, and RSS on vascular smooth muscle cells, endothelial cells, and macrophages and focus on how changes in their production affect the initiation and progression of atherosclerosis. This review also discusses the contribution of ROS, RNS, and RSS in mediating various post-translational modifications, such as oxidation, nitrosylation, and sulfation, of the molecules involved in inflammatory signaling.

Reactive oxygen species downregulate dystroglycans in the megakaryocytes of rats with arterial hypertension

Hypertension is a multifactorial disease characterized by vascular and renal dysfunction, cardiovascular remodeling, inflammation, and fibrosis, all of which are associated with oxidative stress. We previously demonstrated cellular reactive oxygen species (ROS) imbalances may impact the structural and biochemical functions of blood cells and reported downregulation of β-dystroglycan (β-Dg) and overexpression of the epithelial sodium channel (ENaC) contribute to the pathophysiology of hypertension. In this study, we aimed to determine the expression of dystroglycans (Dg) and ENaC in platelet progenitors (megakaryocytes) and their surrounding niches. Thin sections of bone marrow from 5- and 28-week-old spontaneous hypertensive rats (SHR) were compared to age-matched normotensive rats (WKY). Cytometry and immunohistochemical assays demonstrated an oxidative environment in SHR bone marrow, characterized by high levels of myeloperoxidase and 3-nitrotyrosine and downregulation of peroxiredoxin II. In addition, transmission electron micrography and confocal microscopy revealed morphological changes in platelets and Mgks from SHR rats, including swollen mitochondria. Quantitative qRT-PCR assays confirmed downregulation of Dg mRNA and immunohistochemistry and western-blotting validated low expression of β-Dg, mainly in the phosphorylated form, in Mgks from 28-week-old SHR rats. Moreover, we observed a progressive increase in β-1 integrin expression in Mgks and extracellular matrix proteins in Mgk niches in SHR rats compared to WKY controls. These results indicate accumulation of ROS promotes oxidative stress within the bone marrow environment and detrimentally affects cellular homeostasis in hypertensive individuals.

Chrysanthemum coronarium L. Extract Attenuates Homocysteine-Induced Vascular Inflammation in Vascular Smooth Muscle Cells

Hyperhomocysteinemia is a main risk factor for phenotypic modulation of vascular smooth muscle cells (VSMCs) and atherosclerosis. Phenotypic switching and proliferation of VSMCs are related to the progression of vascular inflammation. Chrysanthemum coronarium L. is a leafy vegetable with various biological functions, such as antioxidative, anti-inflammatory, and antiproliferative effects. In this study, we aimed to identify the mechanisms underlying the therapeutic and preventive effects of C. coronarium L. extract (CC) in regulating homocysteine (Hcy)-induced vascular inflammation in human aortic VSMCs. CC did not exhibit cytotoxicity and inhibited Hcy-stimulated VSMC proliferation and migration. In addition, CC promoted Hcy-induced expression of VSMC contractile phenotype proteins, including alpha-smooth muscle actin, calponin, and smooth muscle 22α. CC also decreased Hcy-induced accumulation of reactive oxygen species and expression of inflammatory markers nicotinamide adenine dinucleotide phosphate oxidase-4 and soluble epoxide hydrolase. These results showed that CC attenuates Hcy-induced inflammatory responses, highlighting its potential as a therapeutic or preventive target for Hcy-induced vascular inflammation.

Redox Dysregulation of Vascular Smooth Muscle Sirtuin-1 in Thoracic Aortic Aneurysm in Marfan Syndrome

BACKGROUND

Thoracic aortic aneurysms (TAAs) are abnormal aortic dilatations and a major cardiovascular complication of Marfan syndrome. We previously demonstrated a critical role for vascular smooth muscle (VSM) SirT1 (sirtuin-1), a lysine deacetylase, against maladaptive aortic remodeling associated with chronic oxidative stress and aberrant activation of MMPs (matrix metalloproteinases).

METHODS

In this study, we investigated whether redox dysregulation of SirT1 contributed to the pathogenesis of TAA using fibrillin-1 hypomorphic mice (Fbn1mgR/mgR), an established model of Marfan syndrome prone to aortic dissection/rupture.

RESULTS

Oxidative stress markers 3-nitrotyrosine and 4-hydroxynonenal were significantly elevated in aortas of patients with Marfan syndrome. Moreover, reversible oxidative post-translational modifications (rOPTM) of protein cysteines, particularly S-glutathionylation, were dramatically increased in aortas of Fbn1mgR/mgR mice, before induction of severe oxidative stress markers. Fbn1mgR/mgR aortas and VSM cells exhibited an increase in rOPTM of SirT1, coinciding with the upregulation of acetylated proteins, an index of decreased SirT1 activity, and increased MMP2/9 activity. Mechanistically, we demonstrated that TGFβ (transforming growth factor beta), which was increased in Fbn1mgR/mgR aortas, stimulated rOPTM of SirT1, decreasing its deacetylase activity in VSM cells. VSM cell-specific deletion of SirT1 in Fbn1mgR/mgR mice (SMKO-Fbn1mgR/mgR) caused a dramatic increase in aortic MMP2 expression and worsened TAA progression, leading to aortic rupture in 50% of SMKO-Fbn1mgR/mgR mice, compared with 25% of Fbn1mgR/mgR mice. rOPTM of SirT1, rOPTM-mediated inhibition of SirT1 activity, and increased MMP2/9 activity were all exacerbated by the deletion of Glrx (glutaredoxin-1), a specific deglutathionylation enzyme, while being corrected by overexpression of Glrx or of an oxidation-resistant SirT1 mutant in VSM cells.

CONCLUSIONS

Our novel findings strongly suggest a causal role of S-glutathionylation of SirT1 in the pathogenesis of TAA. Prevention or reversal of SirT1 rOPTM may be a novel therapeutic strategy to prevent TAA and TAA dissection/ruptures in individuals with Marfan syndrome, for which, thus far, no targeted therapy has been developed.

Hexahydrocurcumin mitigates angiotensin II-induced proliferation, migration, and inflammation in vascular smooth muscle cells

The proliferation and migration of vascular smooth muscle cells (VSMCs) play vital roles in the pathogenesis of atherosclerosis and hypertension. It has been proposed and verified that hexahydrocurcumin (HHC), a metabolite form of curcumin, has cardiovascular protective effects. This study examined the effect of HHC on angiotensin II (Ang II)-induced proliferation, migration, and inflammation in rat aortic VSMCs and explored the molecular mechanisms related to the processes. The results showed that HHC significantly suppressed Ang II-induced proliferation, migration, and inflammation in VSMCs. HHC inhibited Ang II-induction of the increase in cyclin D1 and decrease in p21 expression in VSMCs. Moreover, HHC attenuated the generation of reactive oxygen species (ROS), and the expression of nuclear factor kappa B (NF-κB), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and matrix metalloproteinases-9 (MMP9) in Ang II-induced VSMCs. The proliferation, migration, inflammation, and ROS production were also inhibited by GKT137831 (NADPH oxidase, NOX1/4 inhibitor) and the combination of HHC and GKT137831. In addition, HHC restored the Ang-II inhibited expression of peroxisome proliferator-activated receptor-γ (PPAR-γ) and peroxisome proliferator activated receptor-γ coactivator-1α (PGC-1α). These findings indicate that HHC may play a protective role in Ang II-promoted proliferation, migration, and inflammation by suppressing NADPH oxidase mediated ROS generation and elevating PPAR-γ and PGC-1α expression. See also Figure 1(Fig. 1).

Thoracic aortopathy in Marfan syndrome overlaps with mechanisms seen in bicuspid aortic valve disease

Background

Thoracic aortopathy is a serious complication which is more often seen in patients with Marfan syndrome (MFS) and patients with a bicuspid aortic valve (BAV) than in individuals with a tricuspid aortic valve (TAV). The identification of common pathological mechanisms leading to aortic complications in non-syndromic and syndromic diseases would significantly improve the field of personalized medicine.

Objective

This study sought to compare thoracic aortopathy between MFS, BAV, and TAV individuals.

Materials and methods

Bicuspid aortic valve (BAV; n = 36), TAV (n = 23), and MFS (n = 8) patients were included. Ascending aortic wall specimen were studied for general histologic features, apoptosis, markers of cardiovascular ageing, expression of synthetic and contractile vascular smooth muscle cells (VSMC), and fibrillin-1 expression.

Results

The MFS group showed many similarities with the dilated BAV. Both patient groups showed a thinner intima (p < 0.0005), a lower expression of contractile VSMCs (p < 0.05), more elastic fiber thinning (p < 0.001), lack of inflammation (p < 0.001), and a decreased progerin expression (p < 0.05) as compared to the TAV. Other features of cardiovascular ageing differed between the BAV and MFS. Dilated BAV patients demonstrated less medial degeneration (p < 0.0001), VSMC nuclei loss (p < 0.0001), apoptosis of the vessel wall (p < 0.03), and elastic fiber fragmentation and disorganization (p < 0.001), as compared to the MFS and dilated TAV.

Conclusion

This study showed important similarities in the pathogenesis of thoracic aortic aneurysms in BAV and MFS. These common mechanisms can be further investigated to personalize treatment strategies in non-syndromic and syndromic conditions.

Natural Monoterpenes as Potential Therapeutic Agents against Atherosclerosis

Traditional herbal medicines based on natural products play a pivotal role in preventing and managing atherosclerotic diseases, which are among the leading causes of death globally. Monoterpenes are a large class of naturally occurring compounds commonly found in many aromatic and medicinal plants. Emerging evidence has shown that monoterpenes have many biological properties, including cardioprotective effects. Remarkably, an increasing number of studies have demonstrated the therapeutic potential of natural monoterpenes to protect against the pathogenesis of atherosclerosis. These findings shed light on developing novel effective antiatherogenic drugs from these compounds. Herein, we provide an overview of natural monoterpenes' effects on atherogenesis and the underlying mechanisms. Monoterpenes have pleiotropic and multitargeted pharmacological properties by interacting with various cell types and intracellular molecular pathways involved in atherogenesis. These properties confer remarkable advantages in managing atherosclerosis, which has been recognized as a multifaceted vascular disease. We also discuss limitations in the potential clinical application of monoterpenes as therapeutic agents against atherosclerosis. We propose perspectives to give new insights into future preclinical research and clinical practice regarding natural monoterpenes.

Non-heme iron overload impairs monocyte to macrophage differentiation via mitochondrial oxidative stress

Iron is a key element for systemic oxygen delivery and cellular energy metabolism. Thus regulation of systemic and local iron metabolism is key for maintaining energy homeostasis. Significant changes in iron levels due to malnutrition or hemorrhage, have been associated with several diseases such as hemochromatosis, liver cirrhosis and COPD. Macrophages are key cells in regulating iron levels in tissues as they sequester excess iron. How iron overload affects macrophage differentiation and function remains a subject of debate. Here we used an in vitro model of monocyte-to-macrophage differentiation to study the effect of iron overload on macrophage function. We found that providing excess iron as soluble ferric ammonium citrate (FAC) rather than as heme-iron complexes derived from stressed red blood cells (sRBC) interferes with macrophage differentiation and phagocytosis. Impaired macrophage differentiation coincided with increased expression of oxidative stress-related genes. Addition of FAC also led to increased levels of cellular and mitochondrial reactive oxygen species (ROS) and interfered with mitochondrial function and ATP generation. The effects of iron overload were reproduced by the mitochondrial ROS-inducer rotenone while treatment with the ROS-scavenger N-Acetylcysteine partially reversed FAC-induced effects. Finally, we found that iron-induced oxidative stress interfered with upregulation of M-CSFR and MAFB, two crucial determinants of macrophage differentiation and function. In summary, our findings suggest that high levels of non-heme iron interfere with macrophage differentiation by inducing mitochondrial oxidative stress. These findings might be important to consider in the context of diseases like chronic obstructive pulmonary disease (COPD) where both iron overload and defective macrophage function have been suggested to play a role in disease pathogenesis.

Induction of ferroptosis promotes vascular smooth muscle cell phenotypic switching and aggravates neointimal hyperplasia in mice

BACKGROUND

Stent implantation-induced neointima formation is a dominant culprit in coronary artery disease treatment failure after percutaneous coronary intervention. Ferroptosis, an iron-dependent regulated cell death, has been associated with various cardiovascular diseases. However, the effect of ferroptosis on neointima formation remains unclear.

METHODS

The mouse common right carotid arteries were ligated for 16 or 30 days, and ligated tissues were collected for further analyses. Primary rat vascular smooth muscle cells (VSMCs) were isolated from the media of aortas of Sprague-Dawley (SD) rats and used for in vitro cell culture experiments.

RESULTS

Ferroptosis was positively associated with neointima formation. In vivo, RAS-selective lethal 3 (RSL3), a ferroptosis activator, aggravated carotid artery ligation-induced neointima formation and promoted VSMC phenotypic conversion. In contrast, a ferroptosis inhibitor, ferrostatin-1 (Fer-1), showed the opposite effects in mice. In vitro, RSL3 promoted rat VSMC phenotypic switching from a contractile to a synthetic phenotype, evidenced by increased contractile markers (smooth muscle myosin heavy chain and calponin 1), and decreased synthetic marker osteopontin. The induction of ferroptosis by RSL3 was confirmed by the increased expression level of ferroptosis-associated gene prostaglandin-endoperoxide synthase 2 (Ptgs2). The effect of RSL3 on rat VSMC phenotypic switching was abolished by Fer-1. Moreover, N-acetyl-L-cysteine (NAC), the reactive oxygen species inhibitor, counteracted the effect of RSL3 on the phenotypic conversion of rat VSMCs.

CONCLUSIONS

Ferroptosis induces VSMC phenotypic switching and accelerates ligation-induced neointimal hyperplasia in mice. Our findings suggest inhibition of ferroptosis as an attractive strategy for limiting vascular restenosis.

Agonist-induced Piezo1 activation promote mitochondrial-dependent apoptosis in vascular smooth muscle cells

OBJECTIVE

Mechanical damage plays an essential role in the progression of atherosclerosis. Piezo1 is a new mechanically sensitive ion channel. The present study investigated the vascular smooth muscle cells (VSMCs) apoptosis induced by Piezo1 activation and explored its underlying mechanism.

METHODS

We evaluated cell viability and apoptosis rate with cell counting kit-8 (CCK-8) and Annexin V-FITC/PI flow cytometry assay, respectively. And then Western blot was performed to measure the relative protein. Reactive oxygen species (ROS) and intracellular Ca²⁺ were assessed via fluorescence microscope, and the mitochondrial transmembrane potential was monitored by JC-10 staining.

RESULTS

Our in vitro study revealed that mice in the ApoE-/- group compared with control mice showed higher Piezo1 expression(P < 0.05). Besides, Yoda1, a Piezo1 agonist, triggered Ca²⁺ overload, mitochondrial damage, accumulation of ROS, and VSMCs apoptosis in a dose-depend manner. Furthermore, BAPT-AM (an intracellular Ca²⁺ chelator) and NAC (an antioxidant) suppressed the mitochondrial damage and attenuated the VSMCs apoptosis.

CONCLUSION

Our study suggested that Piezo1 induced VSMCs apoptosis because of Ca²⁺ overload, excessive ROS generation, and mitochondrial dysfunction, which indicated that Piezo1 has potential value in treating vascular diseases.

Radiation-induced C-reactive protein triggers apoptosis of vascular smooth muscle cells through ROS interfering with the STAT3/Ref-1 complex

Damage to normal tissue can occur over a long period after cancer radiotherapy. Free radical by radiation can initiate or accelerate chronic inflammation, which can lead to atherosclerosis. However, the underlying mechanisms remain unclear. Vascular smooth muscle cells (VSMCs) proliferate in response to JAK/STAT3 signalling. C-reactive protein (CRP) can induce VSMCs apoptosis via triggering NADPH oxidase (NOX). Apoptotic VSMCs promote instability and inflammation of atherosclerotic lesions. Herein, we identified a VSMCs that switched from proliferation to apoptosis through was enhanced by radiation-induced CRP. NOX inhibition using lentiviral sh-p22^phox prevented apoptosis upon radiation-induced CRP. CRP overexpression reduced the amount of STAT3/Ref-1 complex, decreased JAK/STAT phosphorylation and formed a new complex of Ref-1/CRP in VSMC. Apoptosis of VSMCs was further increased by CRP co-overexpressed with Ref-1. Functional inhibition of NOX or p53 also prevented apoptotic activity of the CRP-Ref-1 complex. Immunofluorescence showed co-localization of CRP, Ref-1 and p53 with α-actin-positive VSMC in human atherosclerotic plaques. In conclusion, radiation-induced CRP increased the VSMCs apoptosis through Ref-1, which dissociated the STAT3/Ref-1 complex, interfered with JAK/STAT3 activity, and interacted with CRP-Ref-1, thus resulting in transcription-independent cell death via p53. Targeting CRP as a vascular side effect of radiotherapy could be exploited to improve curability.

PLD1 promotes reactive oxygen species production in vascular smooth muscle cells and injury-induced neointima formation

Phospholipase D (PLD) generates the signaling lipid phosphatidic acid (PA) and has been known to mediate proliferation signal in vascular smooth muscle cells (VSMCs). However, it remains unclear how PLD contributes to vascular diseases. VSMC proliferation directly contributes to the development and progression of cardiovascular disease, such as atherosclerosis and restenosis after angioplasty. Using the mouse carotid artery ligation model, we find that deletion of Pld1 gene inhibits neointima formation of the injuried blood vessels. PLD1 deficiency reduces the proliferation of VSMCs in both injured artery and primary cultures through the inhibition of ERK1/2 and AKT signals. Immunohistochemical staining of injured artery and flow cytometry analysis of VSMCs shows a reduction of the levels of reactive oxygen species (ROS) in Pld1-/- VSMCs. An increase of intracellular ROS by hydrogen peroxide stimulation restored the reduced activities of ERK and AKT in Pld1-/- VSMCs, whereas a reduction of ROS by N-acetyl-l-cysteine (NAC) scavenger lowered their activity in wild-type VSMCs. These results indicate that PLD1 plays a critical role in neointima, and that PLD1 mediates VSMC proliferation signal through promoting the production of ROS. Therefore, inhibition of PLD1 may be used as a therapeutic approach to suppress neointimal formation in atherosclerosis and restenosis after angioplasty.

Multi-Omics Profiling in Marfan Syndrome: Further Insights into the Molecular Mechanisms Involved in Aortic Disease

Thoracic aortic aneurysm is a potentially life-threatening disease with a strong genetic contribution. Despite identification of multiple genes involved in aneurysm formation, little is known about the specific underlying mechanisms that drive the pathological changes in the aortic wall. The aim of our study was to unravel the molecular mechanisms underlying aneurysm formation in Marfan syndrome (MFS). We collected aortic wall samples from FBN1 variant-positive MFS patients (n = 6) and healthy donor hearts (n = 5). Messenger RNA (mRNA) expression levels were measured by RNA sequencing and compared between MFS patients and controls, and between haploinsufficient (HI) and dominant negative (DN) FBN1 variants. Immunohistochemical staining, proteomics and cellular respiration experiments were used to confirm our findings. FBN1 mRNA expression levels were highly variable in MFS patients and did not significantly differ from controls. Moreover, we did not identify a distinctive TGF-β gene expression signature in MFS patients. On the contrary, differential gene and protein expression analysis, as well as vascular smooth muscle cell respiration measurements, pointed toward inflammation and mitochondrial dysfunction. Our findings confirm that inflammatory and mitochondrial pathways play important roles in the pathophysiological processes underlying MFS-related aortic disease, providing new therapeutic options.

An update on the phenotypic switching of vascular smooth muscle cells in the pathogenesis of atherosclerosis

Vascular smooth muscle cells (VSMCs) are involved in phenotypic switching in atherosclerosis. This switching is characterized by VSMC dedifferentiation, migration, and transdifferentiation into other cell types. VSMC phenotypic transitions have historically been considered bidirectional processes. Cells can adopt a physiological contraction phenotype or an alternative "synthetic" phenotype in response to injury. However, recent studies, including lineage tracing and single-cell sequencing studies, have shown that VSMCs downregulate contraction markers during atherosclerosis while adopting other phenotypes, including macrophage-like, foam cell, mesenchymal stem-like, myofibroblast-like, and osteochondral-like phenotypes. However, the molecular mechanism and processes regulating the switching of VSMCs at the onset of atherosclerosis are still unclear. This systematic review aims to review the critical outstanding challenges and issues that need further investigation and summarize the current knowledge in this field.

Coronary Large Conductance Ca2+-Activated K+ Channel Dysfunction in Diabetes Mellitus

Diabetes mellitus (DM) is an independent risk of macrovascular and microvascular complications, while cardiovascular diseases remain a leading cause of death in both men and women with diabetes. Large conductance Ca2+-activated K+ (BK) channels are abundantly expressed in arteries and are the key ionic determinant of vascular tone and organ perfusion. It is well established that the downregulation of vascular BK channel function with reduced BK channel protein expression and altered intrinsic BK channel biophysical properties is associated with diabetic vasculopathy. Recent efforts also showed that diabetes-associated changes in signaling pathways and transcriptional factors contribute to the downregulation of BK channel expression. This manuscript will review our current understandings on the molecular, physiological, and biophysical mechanisms that underlie coronary BK channelopathy in diabetes mellitus.

Oxidative Stress-Related Susceptibility to Aneurysm in Marfan's Syndrome

The involvement of highly reactive oxygen-derived free radicals (ROS) in the genesis and progression of various cardiovascular diseases, including arrhythmias, aortic dilatation, aortic dissection, left ventricular hypertrophy, coronary arterial disease and congestive heart failure, is well-established. It has also been suggested that ROS may play a role in aortic aneurysm formation in patients with Marfan's syndrome (MFS). This syndrome is a multisystem disorder with manifestations including cardiovascular, skeletal, pulmonary and ocular systems, however, aortic aneurysm and dissection are still the most life-threatening manifestations of MFS. In this review, we will concentrate on the impact of oxidative stress on aneurysm formation in patients with MFS as well as on possible beneficial effects of some agents with antioxidant properties. Mechanisms responsible for oxidative stress in the MFS model involve a decreased expression of superoxide dismutase (SOD) as well as enhanced expression of NAD(P)H oxidase, inducible nitric oxide synthase (iNOS) and xanthine oxidase. The results of studies have indicated that reactive oxygen species may be involved in smooth muscle cell phenotype switching and apoptosis as well as matrix metalloproteinase activation, resulting in extracellular matrix (ECM) remodeling. The progression of the thoracic aortic aneurysm was suggested to be associated with markedly impaired aortic contractile function and decreased nitric oxide-mediated endothelial-dependent relaxation.

Human Vascular Smooth Muscle Function and Oxidative Stress Induced by NADPH Oxidase with the Clinical Implications

Among reactive oxygen species, superoxide mediates the critical vascular redox signaling, resulting in the regulation of the human cardiovascular system. The reduced form of nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase, NOX) is the source of superoxide and relates to the crucial intracellular pathology and physiology of vascular smooth muscle cells, including contraction, proliferation, apoptosis, and inflammatory response. Human vascular smooth muscle cells express NOX1, 2, 4, and 5 in physiological and pathological conditions, and those enzymes play roles in most cardiovascular disorders caused by hypertension, diabetes, inflammation, and arteriosclerosis. Various physiologically active substances, including angiotensin II, stimulate NOX via the cytosolic subunits’ translocation toward the vascular smooth muscle cell membrane. As we have shown, some pathological stimuli such as high glucose augment the enzymatic activity mediated by the phosphatidylinositol 3-kinase-Akt pathway, resulting in the membrane translocation of cytosolic subunits of NOXs. This review highlights and details the roles of human vascular smooth muscle NOXs in the pathophysiology and clinical aspects. The regulation of the enzyme expressed in the vascular smooth muscle cells may lead to the prevention and treatment of human cardiovascular diseases.

Ambient Particulate Matter Induces Vascular Smooth Muscle Cell Phenotypic Changes via NOX1/ROS/NF-κB Dependent and Independent Pathways: Protective Effects of Polyphenols

Epidemiological studies have demonstrated an association between ambient particulate matter (PM) exposure and vascular diseases. Here, we observed that treatment with ambient PM increased cell migration ability in vascular smooth muscle cells (VSMCs) and pulmonary arterial SMCs (PASMCs). These results suggest that VSMCs and PASMCs transitioned from a differentiated to a synthetic phenotype after PM exposure. Furthermore, treatment with PM increased intracellular reactive oxygen species (ROS), activated the NF-κB signaling pathway, and increased the expression of proinflammatory cytokines in VSMCs. Using specific inhibitors, we demonstrated that PM increased the migration ability of VSMCs via the nicotinamide–adenine dinucleotide phosphate (NADPH) oxidase 1 (NOX1)/ROS-dependent NF-κB signaling pathway, which also partially involved in the induction of proinflammatory cytokines. Finally, we investigated whether nature polyphenolic compounds prevent PM-induced migration and proinflammatory cytokines secretion in VSMCs. Curcumin, resveratrol, and gallic acid prevented PM_2.5-induced migration via the ROS-dependent NF-κB signaling pathway. However, honokiol did not prevent PM_2.5-induced migration or activation of the ROS-dependent NF-κB signaling pathway. On the other hand, all polyphenols prevented PM_2.5-induced cytokines secretion. These data indicated that polyphenols prevented PM-induced migration and cytokine secretion via blocking the ROS-dependent NF-κB signaling pathway in VSMCs. However, other mechanisms may also contribute to PM-induced cytokine secretion.

Decline in endothelial function across the menopause transition in healthy women is related to decreased estradiol and increased oxidative stress

Endothelial function declines progressively across stages of the menopause transition; however, the mechanisms contributing to this decline are unknown. We hypothesized that differences in endothelial function among pre-, peri, and postmenopausal women are related to differences in estradiol and oxidative stress. Brachial artery flow-mediated dilation (FMD) was measured in 87 healthy women categorized by menopause stage (24 premenopausal, 17 early and 21 late perimenopausal, and 25 postmenopausal) before and after 3 days of ovarian hormone suppression (gonadotropin releasing hormone antagonist [GnRHant]) alone, and an additional 3 days of GnRHant with concurrent transdermal estradiol or placebo add-back treatment. In 82 women, FMD during acute vitamin C (antioxidant) infusion was measured before and after GnRHant + add-back. Before GnRHant, FMD was different among groups (p < 0.005; reduced across stages of menopause). Vitamin C increased FMD in late peri- and post- (p < 0.005) but not pre- or early perimenopausal women (p > 0.54). After GnRHant alone, FMD decreased in pre- and peri- (p < 0.01), but not postmenopausal women, and was restored to premenopausal levels by estradiol add-back in the pre- and perimenopausal groups. Vitamin C improved FMD in pre-, peri-, and postmenopausal women on GnRHant + placebo. There was no effect of vitamin C on FMD in women on GnRHant + estradiol. These observations support the concept that the decline in endothelial function across the menopause transition is related to the loss of ovarian estradiol. The decline in estradiol may alter redox balance, thereby increasing oxidative stress and impairing endothelial function.

Reactive Oxygen Species: Modulators of Phenotypic Switch of Vascular Smooth Muscle Cells

Reactive oxygen species (ROS) are natural byproducts of oxygen metabolism in the cell. At physiological levels, they play a vital role in cell signaling. However, high ROS levels cause oxidative stress, which is implicated in cardiovascular diseases (CVD) such as atherosclerosis, hypertension, and restenosis after angioplasty. Despite the great amount of research conducted to identify the role of ROS in CVD, the image is still far from being complete. A common event in CVD pathophysiology is the switch of vascular smooth muscle cells (VSMCs) from a contractile to a synthetic phenotype. Interestingly, oxidative stress is a major contributor to this phenotypic switch. In this review, we focus on the effect of ROS on the hallmarks of VSMC phenotypic switch, particularly proliferation and migration. In addition, we speculate on the underlying molecular mechanisms of these cellular events. Along these lines, the impact of ROS on the expression of contractile markers of VSMCs is discussed in depth. We conclude by commenting on the efficiency of antioxidants as CVD therapies.

Aortic "Disease-in-a-Dish": Mechanistic Insights and Drug Development Using iPSC-Based Disease Modeling

Thoracic aortic diseases, whether sporadic or due to a genetic disorder such as Marfan syndrome, lack effective medical therapies, with limited translation of treatments that are highly successful in mouse models into the clinic. Patient-derived induced pluripotent stem cells (iPSCs) offer the opportunity to establish new human models of aortic diseases. Here we review the power and potential of these systems to identify cellular and molecular mechanisms underlying disease and discuss recent advances, such as gene editing, and smooth muscle cell embryonic lineage. In particular, we discuss the practical aspects of vascular smooth muscle cell derivation and characterization, and provide our personal insights into the challenges and limitations of this approach. Future applications, such as genotype-phenotype association, drug screening, and precision medicine are discussed. We propose that iPSC-derived aortic disease models could guide future clinical trials via “clinical-trials-in-a-dish”, thus paving the way for new and improved therapies for patients.

Deficiency of peroxiredoxin 2 exacerbates angiotensin II-induced abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is an inflammatory vascular disease characterized by structural deterioration of the aorta caused by inflammation and oxidative stress, leading to aortic dilatation and rupture. Peroxiredoxin 2 (PRDX2), an antioxidant enzyme, has been reported as a potential negative regulator of inflammatory vascular diseases, and it has been identified as a protein that is increased in patients with ruptured AAA compared to patients with nonruptured AAA. In this study, we demonstrated that PRDX2 was a pivotal factor involved in the inhibition of AAA progression. PRDX2 levels were increased in AAA compared with those in normal aortas in both humans and mice. Ultrasound imaging revealed that the loss of PRDX2 accelerated the development of AAA in the early stages and increased AAA incidence in mice infused with angiotensin II (Ang II). Prdx2^−/− mice infused with Ang II exhibited increased aortic dilatation and maximal aortic diameter without a change in blood pressure. Structural deterioration of the aortas from Prdx2^−/− mice infused with Ang II was associated with increases in the degradation of elastin, oxidative stress, and intramural thrombi caused by microhemorrhages, immature neovessels, and the activation of matrix metalloproteinases compared to that observed in controls. Moreover, an increase in inflammatory responses, including the production of cell adhesion molecules and the accumulation of inflammatory cells and proinflammatory cytokines due to PRDX2 deficiency, accelerated Ang II-induced AAA progression. Our data confirm that PRDX2 plays a role as a negative regulator of the pathological process of AAA and suggest that increasing PRDX2 activity may be a novel strategy for the prevention and treatment of AAA.

An enzyme with antioxidant properties may provide a biomarker and therapeutic agent to help treat abdominal aortic aneurysm (AAA). AAA involves the structural deterioration of the aorta through chronic inflammation and oxidative stress, and can trigger life-threatening artery rupture. An antioxidant enzyme called peroxiredoxin 2 (PRDX2) is increased in patients with ruptures, but whether its role in AAA is beneficial or detrimental is unclear. Goo Taeg Oh at the Ewha Womans University in Seoul, Jong-Gil Park at the Korea Research Institute of Bioscience and Biotechnology, Daejeon, South Korea, and co-workers examined the effect of PRDX2 on AAA progression. PRDX2 suppressed structural damage in mice, limiting artery dilation and protein degradation. Loss of PRDX2 accelerated AAA development. Measuring levels of PRDX2 may indicate AAA severity in patients, while boosting the enzyme could repair aortic damage.

EPAC in Vascular Smooth Muscle Cells

Vascular smooth muscle cells (VSMCs) are major components of blood vessels. They regulate physiological functions, such as vascular tone and blood flow. Under pathological conditions, VSMCs undergo a remodeling process known as phenotypic switching. During this process, VSMCs lose their contractility and acquire a synthetic phenotype, where they over-proliferate and migrate from the tunica media to the tunica interna, contributing to the occlusion of blood vessels. Since their discovery as effector proteins of cyclic adenosine 3′,5′-monophosphate (cAMP), exchange proteins activated by cAMP (EPACs) have been shown to play vital roles in a plethora of pathways in different cell systems. While extensive research to identify the role of EPAC in the vasculature has been conducted, much remains to be explored to resolve the reported discordance in EPAC’s effects. In this paper, we review the role of EPAC in VSMCs, namely its regulation of the vascular tone and phenotypic switching, with the likely involvement of reactive oxygen species (ROS) in the interplay between EPAC and its targets/effectors.

Redox signaling modulates Rho activity and tissue contractility in the Caenorhabditis elegans spermatheca

Actomyosin-based contractility in smooth muscle and nonmuscle cells is regulated by signaling through the small GTPase Rho and by calcium-activated pathways. We use the myoepithelial cells of the Caenorhabditis elegans spermatheca to study the mechanisms of coordinated myosin activation in vivo. Here, we show that redox signaling modulates RHO-1/Rho activity in this contractile tissue. Exogenously added as well as endogenously generated hydrogen peroxide decreases spermathecal contractility by inhibition of RHO-1, which depends on a conserved cysteine in its nucleotide binding site (C20). Further, we identify an endogenous gradient of H₂O₂ across the spermathecal tissue, which depends on the activity of cytosolic superoxide dismutase, SOD-1. Collectively, we show that SOD-1-mediated H₂O₂ production regulates the redox environment and fine tunes Rho activity across the spermatheca through oxidation of RHO-1 C20.

Identification of ambient fine particulate matter components related to vascular dysfunction by analyzing spatiotemporal variations

Exposure to ambient fine particulate matter (PM_2.5) has been associated with vascular diseases in epidemiological studies. We have demonstrated previously that exposure to ambient PM_2.5 caused pulmonary vascular remodeling in mice and increased vascular smooth muscle cells (VSMCs) viability. Here, we further demonstrated that exposure of mice to ambient PM_2.5 increased urinary 8‑hydroxy‑2'‑deoxyguanosine (8-OHdG) and cytokines concentrations in the broncheoalveolar lavage. The objective of the present study was to identify the PM_2.5 components related to vascular dysfunction. Exposure to PM_2.5 collected from various areas and seasons in Taiwan significantly increased viability, oxidative stress, and inflammatory cytokines secretion in VSMCs. The mass concentrations of benz[a]anthracene (BaA), benzo[e]pyrene (BeP), perylene, dibenzo[a,e]pyrene, molybdenum, zinc (Zn), vanadium (V), and nickel in the PM_2.5 were significantly associated with increased viability of VSMCs. These components, except BaA and BeP, also were significantly associated with chemokine (CC motif) ligand 5 (CCL5) concentrations in the VSMCs. The effects of V and Zn on cell viability and CCL5 expression, respectively, were verified. In addition, the mass concentrations of sulfate and manganese (Mn) in PM_2.5 were significantly correlated with increased oxidative stress; this correlation was also confirmed. After extraction, the inorganic fraction of PM_2.5 increased cell viability and oxidative stress, but the organic fraction of PM_2.5 increased only cell viability, which was inhibited by an aryl hydrocarbon receptor antagonist. These data suggest that controlling the emission of Zn, V, Mn, sulfate, and PAHs may prevent the occurrence of PM_2.5-induced vascular diseases.

The Role of Hydrogen Peroxide and Peroxiredoxins throughout the Cell Cycle

Hydrogen peroxide (H₂O₂) is an oxidizing agent that induces cellular damage at inappropriate concentrations and gives rise to an arrest during cell cycle progression, causing cell death. Recent evidence indicates that H₂O₂ also acts as a promoter for cell cycle progression by oxidizing specific thiol proteins. The intracellular concentration of H₂O₂ is regulated tightly, enabling its use as a cellular signaling molecule while minimizing its potential to cause cellular damage. Peroxiredoxins (Prxs) have peroxidase activity toward H₂O₂, organic hydroperoxides, and peroxynitrite for protecting cells from oxidative stress. They are suggested to work as signaling mediators, allowing the local accumulation of H₂O₂ by inactivating their peroxidase activity uniquely compared with other antioxidant proteins such as catalase and glutathione peroxidase. Given that Prxs are highly sensitive to oxidation by H₂O₂, they act as sensors and transducers of H₂O₂ signaling via transferring their oxidation state to effector proteins. The concentrations of intracellular H₂O₂ increase as the cell cycle progresses from G₁ to mitosis. Here, we summarize the roles of Prxs with regard to the regulation of cell cycle-dependent kinase activity and anaphase-promoting complex/cyclosome in terms of changes in H₂O₂ levels. Protection of the cell from unwanted progression of the cell cycle is suggested to be a role of Prx. We discuss the possible roles of Prxs to control H₂O₂ levels.

The Diabetes Mellitus-Atherosclerosis Connection: The Role of Lipid and Glucose Metabolism and Chronic Inflammation

Diabetes mellitus comprises a group of carbohydrate metabolism disorders that share a common main feature of chronic hyperglycemia that results from defects of insulin secretion, insulin action, or both. Insulin is an important anabolic hormone, and its deficiency leads to various metabolic abnormalities in proteins, lipids, and carbohydrates. Atherosclerosis develops as a result of a multistep process ultimately leading to cardiovascular disease associated with high morbidity and mortality. Alteration of lipid metabolism is a risk factor and characteristic feature of atherosclerosis. Possible links between the two chronic disorders depending on altered metabolic pathways have been investigated in numerous studies. It was shown that both types of diabetes mellitus can actually induce atherosclerosis development or further accelerate its progression. Elevated glucose level, dyslipidemia, and other metabolic alterations that accompany the disease development are tightly involved in the pathogenesis of atherosclerosis at almost every step of the atherogenic process. Chronic inflammation is currently considered as one of the key factors in atherosclerosis development and is present starting from the earliest stages of the pathology initiation. It may also be regarded as one of the possible links between atherosclerosis and diabetes mellitus. However, the data available so far do not allow for developing effective anti-inflammatory therapeutic strategies that would stop atherosclerotic lesion progression or induce lesion reduction. In this review, we summarize the main aspects of diabetes mellitus that possibly affect the atherogenic process and its relationship with chronic inflammation. We also discuss the established pathophysiological features that link atherosclerosis and diabetes mellitus, such as oxidative stress, altered protein kinase signaling, and the role of certain miRNA and epigenetic modifications.

TGF-β3 Induces Autophagic Activity by Increasing ROS Generation in a NOX4-Dependent Pathway

Higher concentrations of reactive oxygen species (ROS) have been associated with epithelial cell damage, cell shedding, and airway hyperresponsiveness. Previous studies have indicated that transforming growth factor-beta (TGF-β) mediates ROS production and NADPH oxidase (NOX) activity. In our previous study, we also observed that TGF-β3 increases mucus secretion in airway epithelial cells in an autophagy-dependent fashion. Although it is well known that the relationship between ROS and autophagy is cell context-dependent, the exact mechanism of action remains unclear. The following study examined whether ROS act as upstream of autophagy activation in response to TGF-β3 induction. Using an allergic inflammation mouse model induced by house dust mite (HDM), we observed elevated lung amounts of TGF-β3 accompanied by increased ROS levels. And we found that ROS levels were elevated and NOX4 expression was increased in TGF-β3-induced epithelial cells, while the lack of NOX4 in the epithelial cells could reduce ROS generation and autophagy-dependent MUC5AC expression treated with TGF-β3. Furthermore, our studies demonstrated that the Smad2/3 pathway was involved in TGF-β3-induced ROS generation by promoting NOX4 expression. The inhibition of ROS generation by N-Acetyl-L-cysteine (NAC) resulted in a decrease in mucus expression and autophagy activity in vivo as well as in vitro. Finally, TGF-β3-neutralizing antibody significantly reduced the ROS generation, mucus expression, and autophagy activity and also decreased the phosphorylation of Smad2 and Smad3. Taken together, the obtained results revealed that persistent TGF-β3 activation increased ROS levels in a NOX4-dependent pathway and subsequently induced autophagy as well as MUC5AC expression in the epithelial cells.

Redox Regulation of the Microcirculation

The microcirculation maintains tissue homeostasis through local regulation of blood flow and oxygen delivery. Perturbations in microvascular function are characteristic of several diseases and may be early indicators of pathological changes in the cardiovascular system and in parenchymal tissue function. These changes are often mediated by various reactive oxygen species and linked to disruptions in pathways such as vasodilation or angiogenesis. This overview compiles recent advances relating to redox regulation of the microcirculation by adopting both cellular and functional perspectives. Findings from a variety of vascular beds and models are integrated to describe common effects of different reactive species on microvascular function. Gaps in understanding and areas for further research are outlined. © 2020 American Physiological Society. Compr Physiol 10:229-260, 2020.

Vanadium Derivative Exposure Promotes Functional Alterations of VSMCs and Consequent Atherosclerosis via ROS/p38/NF-κB-Mediated IL-6 Production

Vanadium is a transition metal widely distributed in the Earth’s crust, and is a major contaminant in fossil fuels. Its pathological effect and regulation in atherosclerosis remain unclear. We found that intranasal administration of the vanadium derivative NaVO₃ significantly increased plasma and urinary vanadium levels and induced arterial lipid accumulation and atherosclerotic lesions in apolipoprotein E-deficient knockout mice (ApoE^−/−) murine aorta compared to those in vehicle-exposed mice. This was accompanied by an increase in plasma reactive oxygen species (ROS) and interleukin 6 (IL-6) levels and a decrease in the vascular smooth muscle cell (VSMC) differentiation marker protein SM22α in the atherosclerotic lesions. Furthermore, exposure to NaVO₃ or VOSO₄ induced cytosolic ROS generation and IL-6 production in VSMCs and promoted VSMC synthetic differentiation, migration, and proliferation. The anti-oxidant N-acetylcysteine (NAC) not only suppresses IL-6 production and VSMC pathological responses including migration and proliferation but also prevents atherosclerosis in ApoE^−/− mice. Inhibition experiments with NAC and pharmacological inhibitors demonstrated that NaVO₃-induced IL-6 production is signaled by ROS-triggered p38-mediated NF-κB-dependent pathways. Neutralizing anti-IL-6 antibodies impaired NaVO₃-mediated VSMC migration and proliferation. We concluded that NaVO₃ exposure activates the ROS-triggering p38 signaling to selectively induce NF-κB-mediated IL-6 production. These signaling pathways induce VSMC synthetic differentiation, migration, and proliferation, leading to lipid accumulation and atherosclerosis.

Reactive Oxygen Species-Dependent Calpain Activation Contributes to Airway and Pulmonary Vascular Remodeling in Chronic Obstructive Pulmonary Disease

Aims: Airway and pulmonary vascular remodeling is an important pathological feature in the pathogenesis of chronic obstructive pulmonary disease (COPD). Tobacco smoke (TS) induces the production of large amounts of reactive oxygen species (ROS) in COPD lungs. We investigated how ROS lead to airway and pulmonary vascular remodeling in COPD. Results: We used in vitro bronchial and pulmonary artery smooth muscle cells (BSMCs and PASMCs), in vivo TS-induced COPD rodent models, and lung tissues of COPD patients. We found that H2O2 and TS extract (TSE) induced calpain activation in BSMCs and PASMCs. Calpain activation was elevated in smooth muscle of bronchi and pulmonary arterioles in COPD patients and TS-induced COPD rodent models. Calpain inhibition attenuated H2O2- and TSE-induced collagen synthesis and proliferation of BSMCs and PASMCs. Exposure to TS causes increases in airway resistance, right ventricular systolic pressure (RVSP), and thickening of bronchi and pulmonary arteries. Calpain inhibition by smooth muscle-specific knockout of calpain and the calpain inhibitor MDL28170 attenuated increases in airway resistance, RVSP, and thickening of bronchi and pulmonary arteries. Moreover, smooth muscle-specific knockout of calpain did not reduce TS-induced emphysema in the mouse model, but MDL28170 did reduce TS-induced emphysema in the rat model. Innovation: This study provides the first evidence that ROS-induced calpain activation contributes to airway and pulmonary vascular remodeling in TS-induced COPD. Calpain might be a novel therapeutic target for the treatment of COPD. Conclusion: These results indicate that ROS-induced calpain activation contributes to airway and pulmonary vascular remodeling and pulmonary hypertension in COPD.

Sauchinone inhibits angiotensin II-induced proliferation and migration of vascular smooth muscle cells

Hypertension is a common type of cardiovascular disease that remains a major cause of death in the world. Vascular remodelling is an important complication of hypertension, and vascular smooth muscle cells (VSMCs) play a major role in vascular remodelling. Sauchinone is one of the active lignins which has been found to possess vascular protective effects. However, the functional role of sauchinone in hypertension has not been investigated. The aim of this study was to evaluate the role of sauchinone in the angiotensin II (Ang II)-induced vascular remodelling model in VSMCs. The results showed that treatment of sauchinone inhibited Ang II-induced VSMCs proliferation and migration in VSMCs. Sauchinone treatment suppressed the reactive oxygen species (ROS) production and NADPH oxidase (NOX) activity in Ang II-induced VSMCs. The inhibitory effects of Ang II on expressions of VSMCs phenotype markers including α-smooth muscle actin (α-SMA), calponin, osteopontin were mitigated by sauchinone treatment. Furthermore, sauchinone inhibited Ang II-induced over-activation of TGF-β1/Smad3 signalling pathway in VSMCs. Taken together, this study identified sauchinone as a potential agent for preventing vascular remodelling in hypertension.

Protective Effects and Mechanisms of Vaccarin on Vascular Endothelial Dysfunction in Diabetic Angiopathy

Cardiovascular complications are a major leading cause of mortality in patients suffering from type 2 diabetes mellitus (T2DM). Vascular endothelial dysfunction is a core pathophysiological event in the early stage of T2DM and eventually leads to cardiovascular disease. Vaccarin (VAC), an active flavonoid glycoside extracted from vaccariae semen, exhibits extensive biological activities including vascular endothelial cell protection effects. However, little is known about whether VAC is involved in endothelial dysfunction regulation under high glucose (HG) or hyperglycemia conditions. Here, in an in vivo study, we found that VAC attenuated increased blood glucose, increased glucose and insulin tolerance, relieved the disorder of lipid metabolism and oxidative stress, and improved endothelium-dependent vasorelaxation in STZ/HFD-induced T2DM mice. Furthermore, in cultured human microvascular endothelial cell-1 (HMEC-1) cells, we showed that pretreatment with VAC dose-dependently increased nitric oxide (NO) generation and the phosphorylation of eNOS under HG conditions. Mechanistically, VAC-treated HMEC-1 cells exhibited higher AMPK phosphorylation, which was attenuated by HG stimulation. Moreover, HG-triggered miRNA-34a upregulation was inhibited by VAC pretreatment, which is in accordance with pretreatment with AMPK inhibitor compound C (CC). In addition, both reactive oxygen species (ROS) scavenger N-acetyl-L-cysteine (NAC) and VAC abolished HG-evoked dephosphorylation of AMPK and eNOS, increased miRNA-34a expression, and decreased NO production. These results suggest that VAC impedes HG-induced endothelial dysfunction via inhibition of the ROS/AMPK/miRNA-34a/eNOS signaling cascade.

Tumour necrosis factor-alpha in uraemic serum promotes osteoblastic transition and calcification of vascular smooth muscle cells via extracellular signal-regulated kinases and activator protein 1/c-FOS-mediated induction of interleukin 6 expression

Background

Vascular calcification is enhanced in uraemic chronic haemodialysis patients, likely due to the accumulation of midsize uraemic toxins, such as interleukin 6 (IL-6) and tumor necrosis factor-alpha (TNF-α). Here we have assessed the impact of uraemia on vascular smooth muscle cell (VSMC) calcification and examined the role of IL-6 and TNF-α as possible mediators and, most importantly, its underlying signalling pathway in VSMCs.

Methods

VSMCs were incubated with samples of uraemic serum obtained from patients treated with haemodialysis for renal failure in the Permeability Enhancement to Reduce Chronic Inflammation-I clinical trial. The VSMCs were assessed for IL-6 gene regulation and promoter activation in response to uraemic serum and TNF-α with reporter assays and electrophoretic mobility shift assay and for osteoblastic transition, cellular calcification and cell viability upon osteogenic differentiation.

Results

Uraemic serum contained higher levels of TNF-α and IL-6 compared with serum from healthy individuals. Exposure of VSMCs to uraemic serum or recombinant TNF-α lead to a strong upregulation of IL-6 mRNA expression and protein secretion, which was mediated by activator protein 1 (AP-1)/c-FOS-pathway signalling. Uraemic serum induced osteoblastic transition and calcification of VSMCs could be strongly attenuated by blocking TNF-α, IL-6 or AP-1/c-FOS signalling, which was accompanied by improved cell viability.

Conclusion

These results demonstrate that uraemic serum contains higher levels of uraemic toxins TNF-α and IL-6 and that uraemia promotes vascular calcification through a signalling pathway involving TNF-α, IL-6 and the AP-1/c-FOS cytokine-signalling axis. Thus treatment modalities aiming to reduce systemic TNF-α and IL-6 levels in chronic haemodialysis patients should be evaluated in future clinical trials.

Involvement of the Akt-dependent CREB signaling pathway in hydrogen-peroxide-induced early growth response protein-1 expression in rat vascular smooth muscle cells

Increased generation of reactive oxygen species is believed to play a key role in the pathophysiology of cardiovascular diseases. Excessive growth and proliferation of vascular smooth muscle cells (VSMCs) have been suggested to be major contributors to vascular dysfunction. Potential involvement of early growth response protein-1 (Egr-1), a zinc finger transcription factor, in the development of vascular diseases has been suggested. Recent studies have shown that the reactive oxygen species hydrogen peroxide (H2O2) increases Egr-1 expression in VSMCs; however, signaling events leading to H2O2-induced Egr-1 expression are not fully understood. Therefore, we aimed to determine the signaling pathways implicated in H2O2-induced Egr-1 expression in rat VSMCs. Pharmacological blockade of the phosphatidylinositol 3-kinase/Akt pathway by wortmannin or SC66 significantly inhibited the protein and mRNA levels of Egr-1 induced by H2O2. H2O2-induced Egr-1 expression was associated with increased phosphorylation of cyclic AMP response element-binding (CREB) protein, and pharmacological inhibition or silencing of Akt attenuated both H2O2-induced CREB phosphorylation and Egr-1 expression. Moreover, RNA interference-mediated depletion of CREB almost completely suppressed the stimulatory effect of H2O2 on Egr-1 expression. Pharmacological blockade or silencing of c-Src resulted in significant suppression of H2O2-induced Egr-1 expression as well as Akt and CREB phosphorylation. These data show that H2O2 enhances the expression of Egr-1, which was associated with increased phosphorylation of Akt, and H2O2 triggers its effects on Egr-1 expression through c-Src–mediated Akt and CREB-dependent signaling events in VSMCs.

RAS/MAPK signaling functions in oxidative stress, DNA damage response and cancer progression

Mitogen-activated protein kinase (MAPK) signaling pathways organize a great constitution network that regulates several physiological processes, like cell growth, differentiation, and apoptotic cell death. Due to the crucial importance of this signaling pathway, dysregulation of the MAPK signaling cascades is involved in the pathogenesis of various human cancer types. Oxidative stress and DNA damage are two important factors which in common lead to carcinogenesis through dysregulation of this signaling pathway. Reactive oxygen species (ROS) are a common subproduct of oxidative energy metabolism and are considered to be a significant physiological modulator of several intracellular signaling pathways including the MAPK pathway. Studies demonstrated that the MAP kinases extracellular signal-regulated kinase (ERK) 1/2 and p38 were activated in response to oxidative stress. In addition, DNA damage is a partly common circumstance in cell life and may result in mutation, cancer, and even cell death. Recently, accumulating evidence illustrated that the MEK/ERK pathway is associated with the suitable performance of cellular DNA damage response (DDR), the main pathway of tumor suppression. During DDR, the MEK/ERK pathway is regularly activated, which contributes to the appropriate activation of DDR checkpoints to inhibit cell division. Therefore, the aim of this review is to comprehensively discuss the critical function of MAPK signaling in oxidative stress, DNA damage, and cancer progression.

Anatomically specific reactive oxygen species production participates in Marfan syndrome aneurysm formation

Marfan syndrome (MFS) is a connective tissue disorder that results in aortic root aneurysm formation. Reactive oxygen species (ROS) seem to play a role in aortic wall remodelling in MFS, although the mechanism remains unknown. MFS Fbn1^C1039G/+ mouse root/ascending (AS) and descending (DES) aortic samples were examined using DHE staining, lucigenin‐enhanced chemiluminescence (LGCL), Verhoeff's elastin‐Van Gieson staining (elastin breakdown) and in situ zymography for protease activity. Fbn1^C1039G/+ AS‐ or DES‐derived smooth muscle cells (SMC) were treated with anti‐TGF‐β antibody, angiotensin II (AngII), anti‐TGF‐β antibody + AngII, or isotype control. ROS were detected during early aneurysm formation in the Fbn1^C1039G/+ AS aorta, but absent in normal‐sized DES aorta. Fbn1^C1039G/+ mice treated with the unspecific NADPH oxidase inhibitor, apocynin reduced AS aneurysm formation, with attenuated elastin fragmentation. In situ zymography revealed apocynin treatment decreased protease activity. In vitro SMC studies showed Fbn1^C1039G/+‐derived AS SMC had increased NADPH activity compared to DES‐derived SMC. AS SMC NADPH activity increased with AngII treatment and appeared TGF‐β dependent. In conclusion, ROS play a role in MFS aneurysm development and correspond anatomically with aneurysmal aortic segments. ROS inhibition via apocynin treatment attenuates MFS aneurysm progression. AngII enhances ROS production in MFS AS SMCs and is likely TGF‐β dependent.

GPCR transactivation signalling in vascular smooth muscle cells: role of NADPH oxidases and reactive oxygen species

The discovery and extension of G-protein-coupled receptor (GPCR) transactivation-dependent signalling has enormously broadened the GPCR signalling paradigm. GPCRs can transactivate protein tyrosine kinase receptors (PTKRs) and serine/threonine kinase receptors (S/TKRs), notably the epidermal growth factor receptor (EGFR) and transforming growth factor-β type 1 receptor (TGFBR1), respectively. Initial comprehensive mechanistic studies suggest that these two transactivation pathways are distinct. Currently, there is a focus on GPCR inhibitors as drug targets, and they have proven to be efficacious in vascular diseases. With the broadening of GPCR transactivation signalling, it is therefore important from a therapeutic perspective to find a common transactivation pathway of EGFR and TGFBR1 that can be targeted to inhibit complex pathologies activated by the combined action of these receptors. Reactive oxygen species (ROS) are highly reactive molecules and they act as second messengers, thus modulating cellular signal transduction pathways. ROS are involved in different mechanisms of GPCR transactivation of EGFR. However, the role of ROS in GPCR transactivation of TGFBR1 has not yet been studied. In this review, we will discuss the involvement of ROS in GPCR transactivation-dependent signalling.