Angiotensin II enhances AT1-Nox1 binding and stimulates arterial smooth muscle cell migration and proliferation through AT1, Nox1, and interleukin-18

Immunomodulatory Activity of Cytokines in Hypertension: A Vascular Perspective

Cytokines play a crucial role in the structure and function of blood vessels in hypertension. Hypertension damages blood vessels by mechanisms linked to shear forces, activation of the renin-angiotensin-aldosterone and sympathetic nervous systems, oxidative stress, and a proinflammatory milieu that lead to the generation of neoantigens and damage-associated molecular patterns, ultimately triggering the release of numerous cytokines. Damage-associated molecular patterns are recognized by PRRs (pattern recognition receptors) and activate inflammatory mechanisms in endothelial cells, smooth muscle cells, perivascular nerves, and perivascular adipose tissue. Activated vascular cells also release cytokines and express factors that attract macrophages, dendritic cells, and lymphocytes to the blood vessels. Activated and differentiated T cells into Th1, Th17, and Th22 in secondary lymphoid organs migrate to the vessels, releasing specific cytokines that further contribute to vascular dysfunction and remodeling. This chronic inflammation alters the profile of endothelial and smooth muscle cells, making them dysfunctional. Here, we provide an overview of how cytokines contribute to hypertension by impacting the vasculature. Furthermore, we explore clinical perspectives about the modulation of cytokines as a potential therapeutic intervention to specifically target hypertension-linked vascular dysfunction.

Protein disulfide isomerase-mediated transcriptional upregulation of Nox1 contributes to vascular dysfunction in hypertension

Nox1 signaling is a causal key element in arterial hypertension. Recently, we identified protein disulfide isomerase A1 (PDI) as a novel regulatory protein that regulates Nox1 signaling in VSMCs. Spontaneously hypertensive rats (SHR) have increased levels of PDI in mesenteric resistance arteries compared with Wistar controls; however, its consequences remain unclear. Herein, we investigated the role of PDI in mediating Nox1 transcriptional upregulation and its effects on vascular dysfunction in hypertension. We demonstrate that PDI contributes to the development of hypertension via enhanced transcriptional upregulation of Nox1 in vascular smooth muscle cells (VSMCs). We show for the first time that PDI sulfenylation by hydrogen peroxide contributes to EGFR activation in hypertension via increased shedding of epidermal growth factor-like ligands. PDI also increases intracellular calcium levels, and contractile responses induced by ANG II. PDI silencing or pharmacological inhibition in VSMCs significantly decreases EGFR activation and Nox1 transcription. Overexpression of PDI in VSMCs enhances ANG II-induced EGFR activation and ATF1 translocation to the nucleus. Mechanistically, PDI increases ATF1-induced Nox1 transcription and enhances the contractile responses to ANG II. Herein we show that ATF1 binding to Nox1 transcription putative regulatory regions is augmented by PDI. Altogether, we provide evidence that HB-EGF in SHR resistance vessels promotes the nuclear translocation of ATF1, under the control of PDI, and thereby induces Nox1 gene expression and increases vascular reactivity. Thus, PDI acts as a thiol redox-dependent enhancer of vascular dysfunction in hypertension and could represent a novel therapeutic target for the treatment of this disease.

Immune and inflammatory mechanisms in hypertension

Hypertension is a global health problem, with >1.3 billion individuals with high blood pressure worldwide. In this Review, we present an inflammatory paradigm for hypertension, emphasizing the crucial roles of immune cells, cytokines and chemokines in disease initiation and progression. T cells, monocytes, macrophages, dendritic cells, B cells and natural killer cells are all implicated in hypertension. Neoantigens, the NLRP3 inflammasome and increased sympathetic outflow, as well as cytokines (including IL-6, IL-7, IL-15, IL-18 and IL-21) and a high-salt environment, can contribute to immune activation in hypertension. The activated immune cells migrate to target organs such as arteries (especially the perivascular fat and adventitia), kidneys, the heart and the brain, where they release effector cytokines that elevate blood pressure and cause vascular remodelling, renal damage, cardiac hypertrophy, cognitive impairment and dementia. IL-17 secreted by CD4+ T helper 17 cells and γδ T cells, and interferon-γ and tumour necrosis factor secreted by immunosenescent CD8+ T cells, exert crucial effector roles in hypertension, whereas IL-10 and regulatory T cells are protective. Effector mediators impair nitric oxide bioavailability, leading to endothelial dysfunction and increased vascular contractility. Inflammatory effector mediators also alter renal sodium and water balance and promote renal fibrosis. These mechanisms link hypertension with obesity, autoimmunity, periodontitis and COVID-19. A comprehensive understanding of the immune and inflammatory mechanisms of hypertension is crucial for safely and effectively translating the findings to clinical practice.

Vascular Inflammation and Smooth Muscle Contractility: The Role of Nox1-Derived Superoxide and LRRC8 Anion Channels

Vascular inflammation underlies the development of hypertension, and the mechanisms by which it increases blood pressure remain the topic of intense investigation. Proinflammatory factors including glucose, salt, vasoconstrictors, cytokines, wall stress, and growth factors enhance contractility and impair relaxation of vascular smooth muscle cells. These pathways share a dependence upon redox signaling, and excessive activation promotes oxidative stress that promotes vascular aging. Vascular smooth muscle cell phenotypic switching and migration into the intima contribute to atherosclerosis, while hypercontractility increases systemic vascular resistance and vasospasm that can trigger ischemia. Here, we review factors that drive the initiation and progression of this vasculopathy in vascular smooth muscle cells. Emphasis is placed on the contribution of reactive oxygen species generated by the Nox1 NADPH oxidase which produces extracellular superoxide (O2•-). The mechanisms of O2•- signaling remain poorly defined, but recent evidence demonstrates physical association of Nox1 with leucine-rich repeat containing 8 family volume-sensitive anion channels. These may provide a pathway for influx of O2•- to the cytoplasm, creating an oxidized cytoplasmic nanodomain where redox-based signals can affect both cytoskeletal structure and vasomotor function. Understanding the mechanistic links between inflammation, O2•- and vascular smooth muscle cell contractility may facilitate targeting of anti-inflammatory therapy in hypertension.

Immune cells and hypertension

Hypertension is one of the leading causes of death due to target organ injury from cardiovascular disease. Although there are many treatments, only one-sixth of hypertensive patients effectively control their blood pressure. Therefore, further understanding the pathogenesis of hypertension is essential for the treatment of hypertension. Much research shows that immune cells play an important role in the pathogenesis of hypertension. Here, we discuss the roles of different immune cells in hypertension. Many immune cells participate in innate and adaptive immune responses, such as monocytes/macrophages, neutrophils, dendritic cells, NK cells, and B and T lymphocytes. Immune cells infiltrate the blood vessels, kidneys, and hearts and cause damage. The mechanism is that immune cells secrete cytokines such as interleukin, interferon, and tumor necrosis factor, which affect the inflammatory reaction, oxidative stress, and kidney sodium water retention, and finally aggravate or reduce the dysfunction, remodeling, and fibrosis of the blood vessel, kidney, and heart to participate in blood pressure regulation. This article reviews the research progress on immune cells and hypertension.

Transcription factors: key regulatory targets of vascular smooth muscle cell in atherosclerosis

Atherosclerosis (AS), leading to gradual occlusion of the arterial lumen, refers to the accumulation of lipids and inflammatory debris in the arterial wall. Despite therapeutic advances over past decades including intervention or surgery, atherosclerosis is still the most common cause of cardiovascular diseases and the main mechanism of death and disability worldwide. Vascular smooth muscle cells (VSMCs) play an imperative role in the occurrence of atherosclerosis and throughout the whole stages. In the past, there was a lack of comprehensive understanding of VSMCs, but the development of identification technology, including in vivo single-cell sequencing technology and lineage tracing with the CreERT2-loxP system, suggests that VSMCs have remarkable plasticity and reevaluates well-established concepts about the contribution of VSMCs. Transcription factors, a kind of protein molecule that specifically recognizes and binds DNA upstream promoter regions or distal enhancer DNA elements, play a key role in the transcription initiation of the coding genes and are necessary for RNA polymerase to bind gene promoters. In this review, we highlight that, except for environmental factors, VSMC genes are transcriptionally regulated through complex interactions of multiple conserved cis-regulatory elements and transcription factors. In addition, through a series of transcription-related regulatory processes, VSMCs could undergo phenotypic transformation, proliferation, migration, calcification and apoptosis. Finally, enhancing or inhibiting transcription factors can regulate the development of atherosclerotic lesions, and the downstream molecular mechanism of transcriptional regulation has also been widely studied.

Can iron, zinc, copper and selenium status be a prognostic determinant in COVID-19 patients?

In severe COVID-19, the levels of iron (Fe), copper (Cu), zinc (Zn) and selenium (Se), do not only regulate host immune responses, but modify the viral genome, as well. While low serum Fe concentration is an independent risk factor for the increased death rate, Zn controls oxidative stress, synthesis of inflammatory cytokines and viral replication. Therefore, Zn deficiency associates with a worse prognosis. Although Cu exposure inactivates the viral genome and exhibits spike protein dispersal, increase in Cu/Zn due to high serum Cu levels, are correlated with enhanced risk of infections. Se levels are significantly higher in surviving COVID-19 patients. Meanwhile, both Zn and Se suppress the replication of SARS-CoV-2. Since the balance between the deficiency and oversupply of these metals due to a reciprocal relationship, has decisive effect on the prognosis of the SARS-CoV-2 infection, monitoring their concentrations may facilitate improved outcomes for patients suffering from COVID-19.

Distinct pathophysiological pathways in women and men with heart failure

AIMS

Clinical differences between women and men have been described in heart failure (HF). However, less is known about the underlying pathophysiological mechanisms. In this study, we compared multiple circulating biomarkers to gain better insights into differential HF pathophysiology between women and men.

METHODS AND RESULTS

In 537 women and 1485 men with HF, we compared differential expression of a panel of 363 biomarkers. Then, we performed a pathway over-representation analysis to identify differential biological pathways in women and men. Findings were validated in an independent HF cohort (575 women, 1123 men). In both cohorts, women were older and had higher left ventricular ejection fraction (LVEF). In the index and validation cohorts respectively, we found 14/363 and 12/363 biomarkers that were relatively up-regulated in women, while 21/363 and 14/363 were up-regulated in men. In both cohorts, the strongest up-regulated biomarkers in women were leptin and fatty acid binding protein-4, compared to matrix metalloproteinase-3 in men. Similar findings were replicated in a subset of patients from both cohorts matched by age and LVEF. Pathway over-representation analysis revealed increased activity of pathways associated with lipid metabolism in women, and neuro-inflammatory response in men (all p < 0.0001).

CONCLUSION

In two independent cohorts of HF patients, biomarkers associated with lipid metabolic pathways were observed in women, while biomarkers associated with neuro-inflammatory response were more active in men. Differences in inflammatory and metabolic pathways may contribute to sex differences in clinical phenotype observed in HF, and provide useful insights towards development of tailored HF therapies.

Fibrotic Signaling in Cardiac Fibroblasts and Vascular Smooth Muscle Cells: The Dual Roles of Fibrosis in HFpEF and CAD

Patients with heart failure with preserved ejection fraction (HFpEF) and atherosclerosis-driven coronary artery disease (CAD) will have ongoing fibrotic remodeling both in the myocardium and in atherosclerotic plaques. However, the functional consequences of fibrosis differ for each location. Thus, cardiac fibrosis leads to myocardial stiffening, thereby compromising cardiac function, while fibrotic remodeling stabilizes the atherosclerotic plaque, thereby reducing the risk of plaque rupture. Although there are currently no drugs targeting cardiac fibrosis, it is a field under intense investigation, and future drugs must take these considerations into account. To explore similarities and differences of fibrotic remodeling at these two locations of the heart, we review the signaling pathways that are activated in the main extracellular matrix (ECM)-producing cells, namely human cardiac fibroblasts (CFs) and vascular smooth muscle cells (VSMCs). Although these signaling pathways are highly overlapping and context-dependent, effects on ECM remodeling mainly act through two core signaling cascades: TGF-β and Angiotensin II. We complete this by summarizing the knowledge gained from clinical trials targeting these two central fibrotic pathways.

COVID-19, Oxidative Stress, and Neuroinflammation in the Depression Route

COVID-19 is associated with oxidative stress, peripheral hyper inflammation, and neuroinflammation, especially in individuals with a more severe form of the disease. Some studies provide evidence on the onset or exacerbation of major depressive disorder (MDD), among other psychiatric disorders due to COVID-19. Oxidative stress and neuroinflammation are associated conditions, especially in the more severe form of MDD and in refractoriness to available therapeutic strategies. Inflammatory cytokines in the COVID-19 hyper inflammation process can activate the hypothalamic–pituitary–adrenal (HPA) axis and the indoleamine-2,3-dioxygenase (IDO) enzyme. IDO activation can reduce tryptophan and increase toxic metabolites of the kynurenine pathway, which increases glial activation, neuroinflammation, toxicity, and neuronal death. This review surveyed a number of studies and analyzed the mechanisms of oxidative stress, inflammation, and neuroinflammation involved in COVID-19 and depression. Finally, the importance of more protocols that can help elucidate the interaction between these mechanisms underlying COVID-19 and MDD and the possible therapeutic strategies involved in the interaction of these mechanisms are highlighted.

Common Inflammatory Mechanisms in COVID-19 and Parkinson's Diseases: The Role of Microbiome, Pharmabiotics and Postbiotics in Their Prevention

In the last decade, metagenomic studies have shown the key role of the gut microbiome in maintaining immune and neuroendocrine systems. Malfunction of the gut microbiome can induce inflammatory processes, oxidative stress, and cytokine storm. Dysfunction of the gut microbiome can be caused by short-term (virus infection and other infectious diseases) or long-term (environment, nutrition, and stress) factors. Here, we reviewed the inflammation and oxidative stress in neurodegenerative diseases and coronavirus infection (COVID-19). Here, we reviewed the renin-angiotensin-aldosterone system (RAAS) involved in the processes of formation of oxidative stress and inflammation in viral and neurodegenerative diseases. Moreover, the coronavirus uses ACE2 receptors of the RAAS to penetrate human cells. The coronavirus infection can be the trigger for neurodegenerative diseases by dysfunction of the RAAS. Pharmabiotics, postbiotics, and next-generation probiotics, are considered as a means to prevent oxidative stress, inflammatory processes, neurodegenerative and viral diseases through gut microbiome regulation.

Targeting purinergic receptors to suppress the cytokine storm induced by SARS-CoV-2 infection in pulmonary tissue

The etiological agent of coronavirus disease (COVID-19) is the new member of the Coronaviridae family, a severe acute respiratory syndrome coronavirus 2 virus (SARS-CoV-2), responsible for the pandemic that is plaguing the world. The single-stranded RNA virus is capable of infecting the respiratory tract, by binding the spike (S) protein on its viral surface to receptors for the angiotensin II-converting enzyme (ACE2), highly expressed in the pulmonary tissue, enabling the interaction of the virus with alveolar epithelial cells promoting endocytosis and replication of viral material. The infection triggers the activation of the immune system, increased purinergic signaling, and the release of cytokines as a defense mechanism, but the response can become exaggerated and prompt the so-called “cytokine storm”, developing cases such as severe acute respiratory syndrome (SARS). This is characterized by fever, cough, and difficulty breathing, which can progress to pneumonia, failure of different organs and death. Thus, the present review aims to compile and correlate the mechanisms involved between the immune and purinergic systems with COVID-19, since the modulation of purinergic receptors, such as A2A, A2B, and P2X7 expressed by immune cells, seems to be effective as a promising therapy, to reduce the severity of the disease, as well as aid in the treatment of acute lung diseases and other cases of generalized inflammation.

Resveratrol as an Adjunctive Therapy for Excessive Oxidative Stress in Aging COVID-19 Patients

The coronavirus disease 2019 (COVID-19) pandemic continues to burden healthcare systems worldwide. COVID-19 symptoms are highly heterogeneous, and the patient may be asymptomatic or may present with mild to severe or fatal symptoms. Factors, such as age, sex, and comorbidities, are key determinants of illness severity and progression. Aging is accompanied by multiple deficiencies in interferon production by dendritic cells or macrophages in response to viral infections, resulting in dysregulation of inflammatory immune responses and excess oxidative stress. Age-related dysregulation of immune function may cause a more obvious pathophysiological response to SARS-CoV-2 infection in elderly patients and may accelerate the risk of biological aging, even after recovery. For more favorable treatment outcomes, inhibiting viral replication and dampening inflammatory and oxidative responses before induction of an overt cytokine storm is crucial. Resveratrol is a potent antioxidant with antiviral activity. Herein, we describe the reasons for impaired interferon production, owing to aging, and the impact of aging on innate and adaptive immune responses to infection, which leads to inflammation distress and immunosuppression, thereby causing fulminant disease. Additionally, the molecular mechanism by which resveratrol could reverse a state of excessive basal inflammatory and oxidative stress and low antiviral immunity is discussed.

An Antioxidant Sesquiterpene Inhibits Osteoclastogenesis Via Blocking IPMK/TRAF6 and Counteracts OVX-Induced Osteoporosis in Mice

Excessive bone resorption induced by increased osteoclast activity in postmenopausal women often causes osteoporosis. Although the pharmacological treatment of osteoporosis has been extensively developed, a safer and more effective treatment is still needed. Here, we found that curcumenol (CUL), an antioxidant sesquiterpene isolated from Curcuma zedoaria, impaired receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclastogenesis in vitro, whereas the osteoblastogenesis of MC3T3-E1 cells was not affected. We further demonstrated that CUL treatment during RANKL-induced osteoclastogenesis promotes proteasomal degradation of TRAF6 by increasing its K48-linked polyubiquitination, leading to suppression of mitogen-activated protein kinases (MAPKs) and NF-κB pathways and the production of reactive oxygen species (ROS). We also showed that inositol polyphosphate multikinase (IPMK) binds with TRAF6 to reduce its K48-linked polyubiquitination under RANKL stimulation. Concurrently, IPMK deficiency inhibits osteoclast differentiation. The binding between IPMK and TRAF6 blocked by CUL treatment was found in our study. Finally, we confirmed that CUL treatment prevented ovariectomy (OVX)-induced bone loss in mice. In summary, our study demonstrates that CUL could impair the stability of TRAF6 enhanced by IPMK and suppress excessive osteoclast activity in estrogen-deficient mice to treat osteoporosis. © 2021 American Society for Bone and Mineral Research (ASBMR).

Changes in blood levels of IL1 family cytokines in patients with essential hypertension after having COVID-19

Pathogenetic progression mechanisms in the SARS-CoV-2–essential hypertension (EAH) system are more complex than interaction at the level of angiotensinconverting enzyme 2 (ACE2). The study was aimed to assess the dynamic changes of the IL1 members (IL1β, IL1α, IL1ra, IL18, IL18BP, IL37) blood levels in patients with EAH 10, 30, and 180 days after having COVID-19 in order to define cytokine-mediated mechanisms of EAH progression during the period following infection. The study involved four groups of patients: with a history of EAH and COVID-19 (pneumonia/no pneumonia), with a history of COVID-19 (pneumonia/no pneumonia) and no EAH. Cytokine levels were determined by enzyme immunoassay. The study results demonstrate the prolonged proinflammatory immune response during the period following infection in patients with EAH (retaining higher levels of IL1β, IL1α, and IL18 on days 10, 30, and 180 after recovery (р < 0.001) compared to levels measured prior to SARS-CoV-2 infection). In the group with no EAH, the balance of assayed cytokines was restored on day 30 of follow-up. The two-fold increase of blood IL18 levels in patients, having a history of EAH and COVID-19 and showing no increase in the IL18ВР levels after 30 days of follow up compared to the values measured prior to infection, is associated with cardiovascular complications occurring during the first six months of follow-up. This makes it possible to hypothesize the importance of these immunoregulatory peptides for the pathogenesis of complications and enhances the relevance of further scientific research.

Gene Polymorphisms of the Renin-Angiotensin-Aldosterone System as Risk Factors for the Development of In-Stent Restenosis in Patients with Stable Coronary Artery Disease

This study investigated the renin-angiotensin-aldosterone system (RAAS) gene polymorphisms as possible genetic risk factors for the restenosis development in patients with drug-eluting stents. 113 participants had coronary artery disease and underwent stenting. The control group consisted of 62 individuals with intact coronary arteries. Patients were divided into two groups: with in-stent restenosis (ISR) and without it. The patients with ISR were classified into subgroups by the terms of the restenosis development and age. Real-time PCR and Restriction Fragment Length Polymorphism-PCR were used to genotype the study participants for RAAS gene polymorphisms. We found that the development of restenosis is generally associated with the minor A allele for renin (REN) rs2368564 and the major TT genotype for angiotensinogen (AGT) rs699. The heterozygous genotype for AGT rs4762 acts as a protective marker. A minor A allele for angiotensin II type 2 receptor (AGTR2) rs1403543 is associated with a risk of restenosis in people under 65 years old. Among patients with the early ISR, heterozygotes for angiotensin II type 1 receptor (AGTR1) rs5186 are more frequent, as well as A allele carriers for AGTR2 rs1403543. A minor homozygous genotype for REN rs41317140 and heterozygous genotype for aldosterone synthase (CYP11B2) rs1799998 are predisposed to the late restenosis. Thus, to choose the effective treatment tactics for patients with coronary artery disease, it is necessary to genotype patients for the RAAS polymorphisms, which, along with age and clinical characteristics, will allow a comprehensive assessment of the risk of the restenosis development after stenting.

The Role of Interleukin-18 in the Development and Progression of Atherosclerosis

Atherosclerosis (AS), as a chronic inflammatory disorder of the cardiovascular system, is one of the leading causes of ischemic heart disease, stroke and peripheral vascular disease. There is growing evidence on the role of innate and adaptive immunity in the pathogenesis of atherosclerosis. Interleukin-18 is one of the novel proinflammatory cytokines involved in atherogenesis, atherosclerotic plaque instability and plaque rupture. In this review, we overview the findings of preclinical and clinical studies about the role and mechanism of action of IL-18 in the pathogenesis of AS, which could offer novel prognostic and therapeutic approaches.

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.

Serum interleukin-18 levels are associated with non-dipping pattern in newly diagnosed hypertensive patients

BACKGROUND

Interleukin-18 (IL-18), a pro-inflammatory cytokine, increases inflammation in the endothelium. Increased inflammation plays an important role in the development of hypertension (HT). IL-18 level is higher in hypertensives than normotensives.

OBJECTIVE

To investigate the relationship between IL-18 level and diurnal blood pressure (BP) variations in newly diagnosed HT patients.

METHODS

This prospective study included 130 subjects referred to outpatient cardiology clinic with an initial diagnosis of HT. The patients were classified as dipper HT (n = 40), non-dipper HT (n = 50), and normotensive (control, n = 40) according to 24-hour ambulatory BP monitoring. All subjects underwent blood sampling after 12 hours of fasting and transthoracic echocardiography.

RESULTS

The serum IL-18 level was significantly higher in the patient group compared with the controls (195.17 ± 93.00 mg/dl vs. 140.75 ± 71.11 mg/dl, P < 0.01) and also in the non-dipper group than in the dipper group (217.3 ± 96.90 mg/dl, 167.5 ± 80.79 mg/dl, P = 0.011). IL-18 level was positively correlated both the night-time SBP and DBP levels (r = 0.29, P = 0.02 and r = 0.34, P < 0.01, respectively). On multivariate linear regression analysis, left atrium diameter, left ventricular mass index, and serum IL-18 level were independent predictors of non-dipping pattern in newly diagnosed HT patients.

CONCLUSION

Higher IL-18 level was particularly associated with an increase in the night-time BP levels. IL-18 can be used as a predictor for non-dipper HT in newly diagnosed HT patients.

The Endothelium as a Target for Anti-Atherogenic Therapy: A Focus on the Epigenetic Enzymes EZH2 and SIRT1

Endothelial cell inflammatory activation and dysfunction are key events in the pathophysiology of atherosclerosis, and are associated with an elevated risk of cardiovascular events. Yet, therapies specifically targeting the endothelium and atherosclerosis are lacking. Here, we review how endothelial behaviour affects atherogenesis and pose that the endothelium may be an efficacious cellular target for antiatherogenic therapies. We discuss the contribution of endothelial inflammatory activation and dysfunction to atherogenesis and postulate that the dysregulation of specific epigenetic enzymes, EZH2 and SIRT1, aggravate endothelial dysfunction in a pleiotropic fashion. Moreover, we propose that commercially available drugs are available to clinically explore this postulation.

Oxidative Stress and Inflammation in COVID-19-Associated Sepsis: The Potential Role of Anti-Oxidant Therapy in Avoiding Disease Progression

Since the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak emerged, countless efforts are being made worldwide to understand the molecular mechanisms underlying the coronavirus disease 2019 (COVID-19) in an attempt to identify the specific clinical characteristics of critically ill COVID-19 patients involved in its pathogenesis and provide therapeutic alternatives to minimize COVID-19 severity. Recently, COVID-19 has been closely related to sepsis, which suggests that most deceases in intensive care units (ICU) may be a direct consequence of SARS-CoV-2 infection-induced sepsis. Understanding oxidative stress and the molecular inflammation mechanisms contributing to COVID-19 progression to severe phenotypes such as sepsis is a current clinical need in the effort to improve therapies in SARS-CoV-2 infected patients. This article aims to review the molecular pathogenesis of SARS-CoV-2 and its relationship with oxidative stress and inflammation, which can contribute to sepsis progression. We also provide an overview of potential antioxidant therapies and active clinical trials that might prevent disease progression or reduce its severity.

NADPH Oxidases and Their Role in Atherosclerosis

The current view on atherosclerosis positions it as a multifactorial disorder that results from the interplay between lipid metabolism disturbances and inflammatory processes. Oxidative stress is proven to be one of the initiating factors in atherosclerosis development, being implicated both in the inflammatory response and in atherogenic modifications of lipoproteins that facilitate lipid accumulation in the arterial wall. The hallmark of oxidative stress is the elevated level of reactive oxygen species (ROS). Correspondingly, the activity of major ROS-generating enzymes, including nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, xanthine oxidases, and cyclooxygenases, is an important element in atherosclerosis development. In particular, the role of NADPH oxidases in atherosclerosis development has become a subject of intensive research. Aberrant activity of NADPH oxidases was shown to be associated with cardiovascular disease in humans. With regard to atherosclerosis, several important pathological components of the disease development, including endothelial dysfunction, inflammation, and vascular remodeling, involve aberrations in NADPH oxidases functioning. In humans, NADPH oxidases are represented by four isoforms expressed in vascular tissues, where they serve as the main source of ROS during atherogenesis. Moreover, recent studies have demonstrated their impact on vascular remodeling processes. Interestingly, one of the NADPH oxidase isoforms, NOX4, was shown to have an atheroprotective effect. Despite the growing evidence of the crucial involvement of NADPH oxidases in atherosclerosis pathogenesis, the available data still remains controversial. In this narrative review, we summarize the current knowledge of the role of NADPH oxidases in atherosclerosis and outline the future directions of research.

Diabetes Mellitus and Vitamin D Deficiency:Comparable Effect on Survival and a DeadlyAssociation after a Myocardial Infarction

Survivors after a myocardial infarction (MI), especially those with diabetes mellitus (DM), remain at high risk of further events. Identifying and treating factors that may influence survival may open new therapeutic strategies. We assessed the impact on prognosis of DM and hypovitaminosis D (hypovitD), alone or combined. In this prospective, observational study, 1081 patients were enrolled surviving an MI and divided into four groups according to their diabetic and VitD status. The primary end-point was composite of all-cause mortality, angina/MI and heart failure (HF). Secondary outcomes were mortality, HF and angina/MI. During a follow-up of 26.1 months (IQR 6.6–64.5), 391 subjects experienced the primary end-point. Patients with DM or hypovitD had similar rate of the composite end-point. Patients with only hypovitD or DM did not differ regarding components of composite end-point (angina p = 0.97, HF p = 0.29, mortality p = 0.62). DM and VitD deficiency had similarly adjusted risks for primary end-point (HR 1.3, 95%CI 1.05–1.61; HR 1.3, 95% CI 1.04–1.64). The adjusted HR for primary composite end-point for patients with hypovitD and DM was 1.69 (95%CI 1.25–2.29, p = 0.001) in comparison to patients with neither hypoD nor DM. In conclusion, DM and hypovitD, individually and synergistically, are associated with a worse outcome after MI.

Oxidative stress induced pyroptosis leads to osteogenic dysfunction of MG63 cells

Periodontitis is characterized by alveolar bone destruction and is one of the most common chronic oral diseases. Inflammatory cytokines released by pyroptosis, which can be triggered by oxidative stress, are critical in the development of periodontitis. This study aims to clarify whether oxidative stress causes osteoblast dysfunction by inducing pyroptosis in the process of periodontitis. We found that treatment with lipopolysaccharide (LPS) led to NLRP3 inflammasome-mediated pyroptosis of MG63 cells as well as decreased cell migration. Of note, LPS stimulation increased LDH release in a time- and dose-dependent manner. However, inhibition of reactive oxygen species with N-acetyl-L-cysteine attenuated oxidative stress-mediated pyroptosis and improved migration injury in osteoblasts treated with LPS. Further, inhibition of the NLRP3 inflammasome with MCC950 improved osteoblast migration and restored the expression of osteogenic differentiation-related proteins such as COL 1, RUNX 2 and ALP. In conclusion, oxidative stress caused by LPS induces pyroptosis in osteoblasts, leading to osteogenic dysfunction.

Renoprotective effect of irbesartan in a rat model of gentamicin-induced nephrotoxicity: Role of oxidative stress

BACKGROUND:

The renin–angiotensin system (RAS) is essential in renal physiology; however, disturbance of the RAS is one of the chief pathways involved in renal injury. Dysregulation of RAS may result in both glomerular and tubulointerstitial injuries through direct effects of angiotensin II (Ang II) type 1 receptor. Irbesartan and other Ang II blockers have renoprotective effect through reduction of on renal inflammations. Therefore, the aim of the present study was to demonstrate the renoprotective effect of irbesartan on gentamicin-induced nephrotoxicity in rats concerning the oxidative stress.

MATERIALS AND METHODS:

Thirty Sprague-Dawley Male rats divided into three groups, Group I (10 rats) treated with distilled water, Group II (10 rats) treated with gentamicin, and Group III (10 rats) treated with gentamicin plus irbesartan for 12 days. Blood urea, serum creatinine, serum malondialdehyde (MDA), superoxide dismutase (SOD), glutathione reductase (GSH), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecules (KIM-1), and cystatin-c were measured in each group.

RESULTS:

Irbesartan significantly reduced blood urea, serum creatinine, serum MDA, NGAL, KIM-1, and cystatin-c P < 0.05. Irbesartan significantly increases SOD P < 0.05 without significant effect in elevation of GSH serum levels.

CONCLUSION:

Irbesartan has renoprotective effect in attenuation of acute nephrotoxicity through modulation of oxidative stress and antioxidant capacity in rats.

Gender differences in the effect of blackberry supplementation in vascular senescence and atherosclerosis in ApoE-/- mice

As the cardiovascular system ages, it becomes more vulnerable to the effects of oxidative stress and inflammation. The aging process, along with external factors such as radiation exposure and lifestyle, induces vascular senescence and accelerates atherosclerotic plaque accumulation. Expression of nicotinamide adenine dinucleotide phosphate oxidase 1 (Nox1), which produces superoxide, is associated with senescence in vascular smooth muscle cells in vitro and atherosclerosis in ApoE^-/- mice in vivo. However, it is unknown whether Nox1 could be down-regulated by nutritional interventions aimed to reduce atherosclerosis. Here we study the effect of blackberry supplementation in Nox1 expression and atherosclerosis. Four-month-old ApoE^-/- male and female mice were fed low-fat, high-fat or high-fat supplemented with 2% freeze-dried blackberry powder diets for 5 weeks. Analysis of the aorta showed that diet supplemented with blackberry significantly decreased plaque accumulation, senescence associated-β-galactosidase and Nox1 expression in the aorta of male but not female mice. The lipid profile was unchanged by blackberry in both female and male animals. Thus, the known role of Nox1 in atherosclerosis suggests that the atheroprotective effect of blackberry is mediated by Nox1 down-regulation in male mice and that Nox1 is regulated in a gender-dependent manner in females.

Irbesartan Attenuates Gentamicin-induced Nephrotoxicity in Rats through Modulation of Oxidative Stress and Endogenous Antioxidant Capacity

Background:

Overproduction of reactive oxygen species and free radicals is the main mechanism beyond gentamicin-induced nephrotoxicity. Irbesartan and other angiotensin II blockers offer significant nephroprotective effect through improvement of renal function and reduction of renal inflammation. Therefore, the objective of this study was to illustrate the nephroprotective effect of irbesartan in rats regarding the oxidative stress of irbesartan biomarkers.

Methods:

Thirty male Sprague–Dawley rats were used; they were divided into three groups: Group I (10 rats) treated with distilled water, Group II (10 rats) treated with gentamicin, and Group III (10 rats) treated with gentamicin plus irbesartan for 12 days. Blood urea, serum creatinine, serum malondialdehyde (MDA), superoxide dismutase (SOD), glutathione reductase (GSH), neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule (KIM-1), and cystatin-c were measured in each group.

Results:

Irbesartan significantly reduced blood urea, serum creatinine, serum MDA, NGAL, KIM-1, and cystatin-c [P < 0.05]. Irbesartan significantly increases SOD [P < 0.05] without significant effect in elevation of GSH serum levels.

Conclusions:

This study concluded that irbesartan has a nephroprotective effect in attenuation of acute nephrotoxicity through modulation of oxidative stress and antioxidant capacity in rats.

Angiotensin II receptor agonist antibodies are associated with microvascular damage in lupus nephritis

Angiotensin II type 1 receptor agonist antibodies (AT1R-AAs) have been associated with hypertension, atherosclerosis and vascular inflammation in human diseases. The aim of the study was to evaluate the prevalence of AT1R-AAs in active lupus nephritis (LN) patients and their association with vascular damage. One hundred and seven active LN patients underwent a complete clinical examination, measurement of AT1R-AAs, ambulatory blood pressure monitoring, carotid intima-media thickness measurement and morphometric analysis of subintimal fibrosis and medial hyperplasia of the vessels in the kidney tissue. Plasma AT1R-AAs were positive in 58 (54.2%) patients. The Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) score, complement C3 and C4 levels and titers of anti-dsDNA antibodies were higher in the group with positive AT1R-AAs compared with those with negative AT1R-AAs. The AT1R-AA titers correlated with anti-dsDNA antibody titers and with complement C3 and C4 serum levels. In the kidney biopsy, the percentage of subintimal fibrosis and the area of medial hyperplasia were greater in the AT1R-AA-positive patients. No differences in arterial pressure, carotid intima-media thickness and response to therapy were detected. In conclusion, AT1R-AAs are prevalent in active LN patients and are associated with histologic features of microvascular damage.

Nox1 downregulators: A new class of therapeutics

Chronic non-communicable diseases share the pathomechanism of increased reactive oxygen species (ROS) production by nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, known as Nox. The recent discovery that expression of Nox1, a Nox isoform that has been implicated in the pathogenesis of cardiovascular and kidney disease and cancer is regulated by the expression and activity of G protein-coupled estrogen receptor (GPER) led to the identification of orally active small-molecule GPER blockers as selective Nox1 downregulators (NDRs). Preclinical studies using NDRs have demonstrated beneficial effects in vascular disease, hypertension, and glomerular renal injury. These findings suggest the therapeutic potential of NDRs, which reduce Nox1 protein levels, not only for cardiovascular disease conditions including arterial hypertension, pulmonary hypertension, heart failure with preserved ejection fraction (HFpEF), and chronic renal disease, but also for other non-communicable diseases, such as cerebrovascular disease and vascular dementia, Alzheimer's disease, autoimmune diseases and cancer, in which elevated Nox1-derived ROS production plays a causal role.

Blockade of AT1 receptor restore the migration of vascular smooth muscle cells in high sodium medium

The present study aimed to test the hypothesis that increased sodium concentration affects the migratory phenotype of vascular smooth muscle cells (VSMCs) independently of the haemodynamic factors. Cell migration was evaluated by wound-healing assay under the following conditions: high sodium (HS, 160 mM) and control (CT, 140 mM). Cell viability was assessed by annexin V and propidium iodide labeling. Cyclooxygenase-2 (COX-2) gene expression was analysed by reverse transcription polymerase chain reaction. ERK1/2 phosphorylation was assessed by western blot. Exposure of VSMCs to HS reduced migration, and AT1R blockade prevented this response. HS increased COX-2 gene expression, and COX-2 blockade prevented the reduction in VSMC migration induced by HS. HS also increased ERK1/2 phosphorylation, and ERK1/2 inhibition recovered VSMC migration as well as blocked COX-2 gene expression. The TXA₂ receptor blocker, but not the prostacyclin receptor blocker, prevented the HS-induced VSMCs migration decrease. HS reduces the migration of VSMCs by increasing COX-2 gene expression via AT1R-ERK1/2 phosphorylation. In addition, increased COX-2 by HS seems to modulate the reduction of VSMCs migration by the TXA₂ receptor.

Identification of platelet-derived growth factor C as a mediator of both renal fibrosis and hypertension

Platelet-derived growth factors (PDGF) have been implicated in kidney disease progression. We previously found that PDGF-C is upregulated at sites of renal fibrosis and that antagonism of PDGF-C reduces fibrosis in the unilateral ureteral obstruction model. We studied the role of PDGF-C in collagen 4A3^-/- ("Alport") mice, a model of progressive renal fibrosis with greater relevance to human kidney disease. Alport mice were crossbred with PDGF-C^-/- mice or administered a neutralizing PDGF-C antibody. Both PDGF-C deficiency and neutralization reduced serum creatinine and blood urea nitrogen levels and mitigated glomerular injury, renal fibrosis, and renal inflammation. Unexpectedly, systolic blood pressure was also reduced in both Alport and wild-type mice treated with a neutralizing PDGF-C antibody. Neutralization of PDGF-C reduced arterial wall thickness in the renal cortex of Alport mice. Aortic rings isolated from anti-PDGF-C-treated wildtype mice exhibited reduced tension and faster relaxation than those of untreated mice. In vitro, PDGF-C upregulated angiotensinogen in aortic tissue and in primary hepatocytes and induced nuclear factor κB (NFκB)/p65-binding to the angiotensinogen promoter in hepatocytes. Neutralization of PDGF-C suppressed transcript expression of angiotensinogen in Alport mice and angiotensin II receptor type 1 in Alport and wildtype mice. Finally, administration of neutralizing PDGF-C antibodies ameliorated angiotensin II-induced hypertension in healthy mice. Thus, in addition to its key role in mediating renal fibrosis, we identified PDGF-C as a mediator of hypertension via effects on renal vasculature and on the renin-angiotensin system. The contribution to both renal fibrosis and hypertension render PDGF-C an attractive target in progressive kidney disease.

Netrin-1 plays a role in the effect of moderate exercise on myocardial fibrosis in rats

INTRODUCTION

This study aimed to investigate the effect of aerobic exercise on the expression of neitrin-1,DCC receptor and myocardial fibrosis in rats with acute myocardial infarction.

METHODS

Twenty-four rats were randomly divided into three groups: the sham group (n = 8), the acute myocardial infarction (AMI) model group (n = 8), and the aerobic exercise treatment after acute myocardial infarction group (ET) (n = 8). After 10 weeks, the serum levels of netrin-1, tumor necrosis factor alpha α (TNF-α), and interleukin 6 (IL-6) were measured. The expression of matrix metalloproteinase 2 and 9 (MMP2, 9), and their inhibitor, tissue inhibitor of metalloproteinase 2 (TIMP2), myocardial netrin-1, and the deleted in colorectal cancer (DCC) receptor were evaluated. Histopathological results were also evaluated. The collagen volume fraction of the myocardial tissues was also calculated.

RESULTS

Compared with the sham group, in the AMI and ET groups, left ventricular end diastolic pressure (LVEDP) were increased, while left ventricular systolic pressure (LVSP), and left ventricular pressure maximal rate of rise and fall (± dp/dtmax) were significantly decreased (P<0.05,). Compared with the AMI group, in the ET group, LVSP, and ±dp/dtmax were significantly increased while LVEDP was decreased (P<0.05). Compared with the sham group, the AMI group and ET groups showed increased levels of serum TNF-α, IL-6 and significantly reduced levels of netrin-1. Levels of TNF-α and IL-6 were significantly reduced in the ET group compared with the AMI group, whereas the level of netrin-1 was increased. The expression of myocardial MMP2 and MMP9 was significantly increased in the AMI group compared with the sham group, whereas that of myocardial netrin-1, TIMP2 and the DCC receptor, was significantly reduced. Compared with the AMI group, the ET group showed reduced expression of myocardial MMP2 and MMP9 proteins, whereas expression of myocardial netrin-1, TIMP2 and the DCC receptor, was significantly increased. The collagen volume fraction of the myocardial tissues was significantly increased in the AMI group and the ET group compared with the sham group, with a greater increase in the AMI group.

CONCLUSIONS

Aerobic exercise increased levels of serum netrin-1, myocardial netrin-1, and the DCC receptor and reduced the expression of myocardial MMP2 and MMP9 proteins, to improve the degree of fibrosis following myocardial infarction in rats.

NLRP3 Inflammasome Is Involved in Calcium-Sensing Receptor-Induced Aortic Remodeling in SHRs

Increasing evidence suggests that the NLRP3 (nucleotide oligomerization domain-like receptor family, pyrin domain containing 3) inflammasome participates in cardiovascular diseases. However, its role and activation mechanism during hypertension remains unclear. In this study, we tested the role and mechanism of calcium-sensing receptor (CaSR) in NLRP3 inflammasome activation during hypertension. We observed that the expressions of CaSR and NLRP3 were increased in spontaneous hypertensive rats (SHRs) along with aortic fibrosis. In vascular smooth muscle cells (VSMCs), the activation of NLRP3 inflammasome associated with CaSR and collagen synthesis was induced by angiotensin II (Ang II). Furthermore, inhibition of CaSR and NLRP3 inflammasome attenuated proinflammatory cytokine release, suggesting that CaSR-mediated activation of the NLRP3 inflammasome may be a therapeutic target in aortic dysfunction and vascular inflammatory lesions.

The effect of Telmisartan on the expression of connexin43 and neointimal hyperplasia in a rabbit iliac artery restenosis model

We established a rabbit iliac artery restenosis model to explore the impact of Telmisartan on the expression of Connexin43 (Cx43) and neointimal hyperplasia. Thirty New Zealand white rabbits were randomly divided into three groups: control group (n = 10), restenosis group (n = 10), and Telmisartan group (n = 10). The restenosis model was established by high-cholesterol diet combined with double-balloon injury of iliac arteries. In addition, Telmisartan at 5 mg/(kg day) was administered to the rabbits of Telmisartan group on the second day after the second balloon injury. All rabbits were killed at the end of the experiment followed by institution policy. Before sacrifice, blood samples were obtained to test serum angiotensinII (AngII). Iliac arteries were isolated for morphological analysis and determining the expression of Cx43 by HE staining, immunohistochemical analysis, reverse transcription-polymerase chain reaction (RT-PCR), and Western Blotting analysis. Then, the local AngII levels of arteries were measured by radioimmunoassay. As compared with controls, the expression of Cx43 mRNA (0.98 ± 0.08) vs. (1.27 ± 0.17), P < 0.01), and Cx43 protein [(0.75 ± 0.08) vs. (0.90 ± 0.08), P < 0.05] of restenosis group were increased, which were significantly higher than those of Telmisartan group [Cx43 mRNA: (1.27 ± 0.17) vs. (1.00 ± 0.20), P < 0.01; Cx43 protein: (0.90 ± 0.08) vs. (0.82 ± 0.05), P < 0.05]. Furthermore, The intima thickness [(266.12 ± 70.27) vs. (2.85 ± 0.19) μm, P < 0.01] and the local AngII [(115.6 ± 15.7) vs. (90.1 ± 7.7), P < 0.05] of restenosis group were raised when compared with controls. Telmisartan group exhibited thinner intima compared with restenosis group [(68.22 ± 24.37) vs. (266.12 ± 70.27), P < 0.01]. However, the local AngII levels between these two groups were approximate. In addition, the plasma concentration of AngII was not significantly different among three groups. In conclusion, Telmisartan can inhibit the expression of connexin43 and neointimal hyperplasia in iliac artery restenosis model.

Docosahexaenoic acid suppresses angiotensin II-induced A7r5 vascular smooth muscle cell proliferation and migration under pulsatile pressure stress

Elevated mechanical stress applied to vascular walls is well known to modulate vascular remodeling and plays a part in the pathogenesis of atherosclerosis. On the other hand, docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid, has been shown to protect against several types of cardiovascular diseases including atherosclerosis and hypertension. The aim of this study was to clarify the effect of pulsatile pressure stress and DHA on angiotensin II-induced proliferation and migration in A7r5 vascular smooth muscle cells (VSMCs). Pulsatile pressure of between 80 and 160 mmHg was repeatedly applied to VSMCs at a frequency of 4 cycles per min using an apparatus that we developed. Cell proliferation and migration were evaluated using a live cell movie analyzer. Application of pulsatile pressure stress for 24 h significantly increased cell proliferation. Angiotensin II also significantly increased cell proliferation in the presence or absence of pressure stress. DHA significantly inhibited angiotensin II-induced cell proliferation regardless of the pressure load. Angiotensin II significantly induced cell migration regardless of the pulsatile pressure load. Pulsatile pressure stress alone slightly, but not significantly, induced cell migration. DHA inhibited angiotensin II-induced VSMC proliferation and migration under abnormal pressure conditions. Pressure stress tended to induce extracellular signal-regulated kinase (ERK) phosphorylation in the absence of angiotensin II, whereas it significantly induced ERK phosphorylation in the presence of angiotensin II. However, the pressure-induced ERK phosphorylation was not observed in the DHA-treated VSMCs. Our findings may contribute to the understanding of the beneficial effect of DHA on various cardiovascular disorders.

NLRP6 Induces Pyroptosis by Activation of Caspase-1 in Gingival Fibroblasts

NLRP6, a member of the nucleotide-binding domain, leucine-rich repeat-containing (NLR) innate immune receptor family, has been reported to participate in inflammasome formation. Activation of inflammasome triggers a caspase-1-dependent programming cell death called pyroptosis. However, whether NLRP6 induces pyroptosis has not been investigated. In this study, we showed that NLRP6 overexpression activated caspase-1 and gasdermin-D and then induced pyroptosis of human gingival fibroblasts, resulting in release of proinflammatory mediators interleukin (IL)-1β and IL-18. Moreover, NLRP6 was highly expressed in gingival tissue of periodontitis compared with healthy controls. Porphyromonas gingivalis, which is a commensal bacterium and has periodontopathic potential, induced pyroptosis of gingival fibroblasts by activation of NLRP6. Together, we, for the first time, identified that NLRP6 could induce pyroptosis of gingival fibroblasts by activation of caspase-1 and may play a role in periodontitis.

Zinc-finger protein 418 overexpression protects against cardiac hypertrophy and fibrosis

Background

This study aimed to investigated the effect and mechanism of zinc-finger protein 418 (ZNF418) on cardiac hypertrophy caused by aortic banding (AB), phenylephrine (PE) or angiotensin II (Ang II) in vivo and in vitro.

Methods

The expression of ZNF418 in hearts of patients with dilated cardiomyopathy (DCM) or hypertrophic cardiomyopathy (HCM) and AB-induced cardiac hypertrophy mice, as well as in Ang II- or PE-induced hypertrophic primary cardiomyocytes was detected by western blotting. Then, the expression of ZNF418 was up-regulated or down-regulated in AB-induced cardiac hypertrophy mice and Ang II -induced hypertrophic primary cardiomyocytes. The hypertrophic responses and fibrosis were evaluated by echocardiography and histological analysis. The mRNA levels of hypertrophy markers and fibrotic markers were detected by RT-qPCR. Furthermore, the phosphorylation and total levels of c-Jun were measured by western blotting.

Results

ZNF418 was markedly down-regulated in hearts of cardiac hypertrophy and hypertrophic primary cardiomyocytes. Down-regulated ZNF418 exacerbated the myocyte size and fibrosis, moreover increased the mRNA levels of ANP, BNP, β-MHC, MCIP1.4, collagen 1a, collagen III, MMP-2 and fibronection in hearts of AB-treated ZNF418 knockout mice or Ang II-treated cardiomyocytes with AdshZNF418. Conversely, these hypertrophic responses were reduced in the ZNF418 transgenic (TG) mice treated by AB and the AdZNF418-transfected primary cardiomyocytes treated by Ang II. Additionally, the deficiency of ZNF418 enhanced the phosphorylation level of c-jun, and overexpression of ZNF418 suppressed the phosphorylation level of c-jun in vivo and in vitro.

Conclusion

ZNF418 maybe attenuate hypertrophic responses by inhibiting the activity of c-jun/AP-1.

Role of the Immune System in Hypertension

High blood pressure is present in more than one billion adults worldwide and is the most important modifiable risk factor of death resulting from cardiovascular disease. While many factors contribute to the pathogenesis of hypertension, a role of the immune system has been firmly established by a large number of investigations from many laboratories around the world. Immunosuppressive drugs and inhibition of individual cytokines prevent or ameliorate experimental hypertension, and studies in genetically-modified mouse strains have demonstrated that lymphocytes are necessary participants in the development of hypertension and in hypertensive organ injury. Furthermore, immune reactivity may be the driving force of hypertension in autoimmune diseases. Infiltration of immune cells, oxidative stress, and stimulation of the intrarenal angiotensin system are induced by activation of the innate and adaptive immunity. High blood pressure results from the combined effects of inflammation-induced impairment in the pressure natriuresis relationship, dysfunctional vascular relaxation, and overactivity of the sympathetic nervous system. Imbalances between proinflammatory effector responses and anti-inflammatory responses of regulatory T cells to a large extent determine the severity of inflammation. Experimental and human studies have uncovered autoantigens (isoketal-modified proteins and heat shock protein 70) of potential clinical relevance. Further investigations on the immune reactivity in hypertension may result in the identification of new strategies for the treatment of the disease.

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

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

NADPH oxidases and vascular remodeling in cardiovascular diseases

Reactive oxygen species (ROS) are key signaling molecules that regulate vascular function and structure in physiological conditions. A misbalance between the production and detoxification of ROS increases oxidative stress that is involved in the vascular remodeling associated with cardiovascular diseases such as hypertension by affecting inflammation, hypertrophy, migration, growth/apoptosis and extracellular matrix protein turnover. The major and more specific source of ROS in the cardiovascular system is the NADPH oxidase (NOX) family of enzymes composed of seven members (NOX1-5, DUOX 1/2). Vascular cells express several NOXs being NOX-1 and NOX-4 the most abundant NOXs present in vascular smooth muscle cells. This review focuses on specific aspects of NOX-1 and NOX-4 isoforms including information on regulation, function and their role in vascular remodeling. In order to obtain a more integrated view about the role of the different NOX isoforms in different types of vascular remodeling, we discuss the available literature not only on hypertension but also in atherosclerosis, restenosis and aortic dilation.

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

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

NAD(P)H

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

The renin angiotensin system, oxidative stress and mitochondrial function in obesity and insulin resistance

Obesity is a complex disease characterized by excessive expansion of adipose tissue and is an important risk factor for chronic diseases such as cardiovascular disorders, hypertension and type 2 diabetes. Moreover, obesity is a major contributor to inflammation and oxidative stress, all of which are key underlying causes for diabetes and insulin resistance. Specifically, adipose tissue secretes bioactives molecules such as inflammatory hormone angiotensin II, generated in the Renin Angiotensin System (RAS) from its precursor angiotensinogen. Accumulated evidence suggests that RAS may serve as a strong link between obesity and insulin resistance. Dysregulation of RAS also occurs in several other tissues including those involved in regulation of glucose and whole body homeostasis as well as insulin sensitivity such as muscle, liver and pancreas and heart. Here we review the scientific evidence for these interactions and potential roles for oxidative stress, inflammation and mitochondrial dysfunction in these target tissues which may mediate effects of RAS in metabolic diseases. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.

Peroxiredoxin 6 (Prdx6) supports NADPH oxidase1 (Nox1)-based superoxide generation and cell migration

Nox1 is an abundant source of reactive oxygen species (ROS) in colon epithelium recently shown to function in wound healing and epithelial homeostasis. We identified Peroxiredoxin 6 (Prdx6) as a novel binding partner of Nox activator 1 (Noxa1) in yeast two-hybrid screening experiments using the Noxa1 SH3 domain as bait. Prdx6 is a unique member of the Prdx antioxidant enzyme family exhibiting both glutathione peroxidase and phospholipase A2 activities. We confirmed this interaction in cells overexpressing both proteins, showing Prdx6 binds to and stabilizes wild type Noxa1, but not the SH3 domain mutant form, Noxa1 W436R. We demonstrated in several cell models that Prdx6 knockdown suppresses Nox1 activity, whereas enhanced Prdx6 expression supports higher Nox1-derived superoxide production. Both peroxidase- and lipase-deficient mutant forms of Prdx6 (Prdx6 C47S and S32A, respectively) failed to bind to or stabilize Nox1 components or support Nox1-mediated superoxide generation. Furthermore, the transition-state substrate analogue inhibitor of Prdx6 phospholipase A2 activity (MJ-33) was shown to suppress Nox1 activity, suggesting Nox1 activity is regulated by the phospholipase activity of Prdx6. Finally, wild type Prdx6, but not lipase or peroxidase mutant forms, supports Nox1-mediated cell migration in the HCT-116 colon epithelial cell model of wound closure. These findings highlight a novel pathway in which this antioxidant enzyme positively regulates an oxidant-generating system to support cell migration and wound healing.

Nox1 in cardiovascular diseases: regulation and pathophysiology

Since its discovery in 1999, a number of studies have evaluated the role of Nox1 NADPH oxidase in the cardiovascular system. Nox1 is activated in vascular cells in response to several different agonists, with its activity regulated at the transcriptional level as well as by NADPH oxidase complex formation, protein stabilization and post-translational modification. Nox1 has been shown to decrease the bioavailability of nitric oxide, transactivate the epidermal growth factor receptor, induce pro-inflammatory signalling, and promote cell migration and proliferation. Enhanced expression and activity of Nox1 under pathologic conditions results in excessive production of reactive oxygen species and dysregulated cellular function. Indeed, studies using genetic models of Nox1 deficiency or overexpression have revealed roles for Nox1 in the pathogenesis of cardiovascular diseases ranging from atherosclerosis to hypertension, restenosis and ischaemia/reperfusion injury. These data suggest that Nox1 is a potential therapeutic target for vascular disease, and drug development efforts are ongoing to identify a specific bioavailable inhibitor of Nox1.

Valsartan attenuates intimal hyperplasia in balloon-injured rat aortic arteries through modulating the angiotensin-converting enzyme 2-angiotensin-(1-7)-Mas receptor axis

The role of the Mas receptor in the activity of valsartan against intimal hyperplasia is unclear. Herein, we investigated the role of the angiotensin-converting enzyme 2 (ACE2)-angiotensin-(1-7)-Mas receptor axis on the activity of valsartan against intimal hyperplasiain balloon-injured rat aortic arteries. Wistar rats were randomized equally into the sham control group, injured group, and injured plus valsartan (20 mg/kg/d)-treated group. Valsartan significantly attenuated the vascular smooth muscle cell proliferation and intimal and medial thickening on days 14 and 28 after injury. The angiotensin-(1-7) levels as well as ACE2 and Mas receptor mRNA/protein expression were significantly decreased in the injured rats, compared to the uninjured rats; meanwhile, the angiotensin II level as well as the ACE and AT1 receptor mRNA/protein expression were increased (all P < 0.05 or < 0.01). Additionally, the p-ERK protein expression was increased (P < 0.01). Treatment with valsartan significantly increased the angiotensin-(1-7) levels as well as ACE2 and Mas receptor mRNA/protein expression but decreased the angiotensin II level, ACE and AT1 receptor mRNA/protein expression, as well as the p-ERK protein expression, compared to the injured group (all P < 0.05 or < 0.01). These results suggest that valsartan attenuates neointimal hyperplasiain balloon-injured rat aortic arteries through activation of the ACE2-angiotensin-(1-7)-Mas axis as well as inhibition of the ACE-angiotensin II-AT1 and p-ERK pathways.

Regulation of mitochondrial morphology by positive feedback interaction between PKCδ and Drp1 in vascular smooth muscle cell

Dynamin-related protein-1 (Drp1) plays a critical role in mitochondrial fission which allows cell proliferation and Mdivi-1, a specific small molecule Drp1 inhibitor, is revealed to attenuate proliferation. However, few molecular mechanisms-related to Drp1 under stimulus for restenosis or atherosclerosis have been investigated in vascular smooth muscle cells (vSMCs). Therefore, we hypothesized that Drp1 inhibition can prevent vascular restenosis and investigated its regulatory mechanism. Angiotensin II (Ang II) or hydrogen peroxide (H2 O2 )-induced proliferation and migration in SMCs were attenuated by down-regulation of Drp1 Ser 616 phosphorylation, which was demonstrated by in vitro assays for migration and proliferation. Excessive amounts of ROS production and changes in mitochondrial membrane potential were prevented by Drp1 inhibition under Ang II and H2 O2 . Under the Ang II stimulation, activated Drp1 interacted with PKCδ and then activated MEK1/2-ERK1/2 signaling cascade and MMP2, but not MMP9. Furthermore, in ex vivo aortic ring assay, inhibition of the Drp1 had significant anti-proliferative and -migration effects for vSMCs. A formation of vascular neointima in response to a rat carotid artery balloon injury was prevented by Drp1 inhibition, which shows a beneficial effect of Drp1 regulation in the pathologic vascular condition. Drp1-mediated SMC proliferation and migration can be prevented by mitochondrial division inhibitor (Mdivi-1) in in vitro, ex vivo and in vivo, and these results suggest the possibility that Drp1 can be a new therapeutic target for restenosis or atherosclerosis.

Gene and microRNA transcriptional signatures of angiotensin II in endothelial cells

Growth of atherosclerotic plaque requires neovascularization (angiogenesis). To elucidate the involvement of angiotensin II (Ang II) in angiogenesis, we performed gene microarray and microRNA (miRNA) polymerase chain reaction array analyses on human coronary artery endothelial cells exposed to moderate concentration of Ang II for 2 and 12 hours. At 12, but not 2, hours, cultures treated with Ang II exhibited shifts in transcriptional activity involving 267 genes (>1.5-fold difference; P < 0.05). Resulting transcriptome was most significantly enriched for genes associated with blood vessel development, angiogenesis, and regulation of proliferation. Majority of upregulated genes implicated in angiogenesis shared a commonality of being either regulators (HES1, IL-18, and CXCR4) or targets (ADM, ANPEP, HES1, KIT, NOTCH4, PGF, and SOX18) of STAT3. In line with these findings, STAT3 inhibition attenuated Ang II-dependent stimulation of tube formation in Matrigel assay. Expression analysis of miRNAs transcripts revealed that the pattern of differential expression for miRNAs was largely consistent with proangiogenic response with a prominent theme of upregulation of miRs targeting PTEN (miR-19b-3p, miR-21-5p, 23b-3p, and 24-3p), many of which are directly or indirectly STAT3 dependent. We conclude that STAT3 signaling may be an intrinsic part of Ang II-mediated proangiogenic response in human endothelial cells.

Change of concept about the regulation of angiotensin II-induced monocyte chemoattractant protein-1 production in human endothelial cells

AIMS

Some intriguing clinical observations about the anti-inflammatory effects of angiotensin type 1 (AT1) receptor blockers and angiotensin converting enzyme inhibitors in cardiovascular patients brought us to study the signalling pathways which lead to angiotensin II (ANG)-induced monocyte chemoattractant protein-1 (MCP-1) production in human endothelial cells.

METHODS

MCP-1 production in human umbilical vein endothelial cells (HUVECs) under treatments with ANG, AT1 and angiotensin type 2 (AT2) receptor blockers and pravastatin was measured by ELISA. The expression of AT1 and AT2 receptors and NADPH oxidase catalytic subunits (NOX 1-5) was analysed at mRNA and protein levels. Nuclear factor-kappa B (NF-κB) activation was studied by p65 subunit translocation to the cellular nucleus. Cell viability was tested by the MTT method. Nox4 subcellular distribution was analysed by subcellular protein fractionation and by immunoprecipitation followed by matrix-assisted laser desorption/ionization mass spectrometry analysis.

RESULTS

ANG-induced MCP-1 production was mediated by AT2 receptor, but not AT1 receptor in HUVECs in culture, which in turn activated NF-κB, promoting p65 subunit translocation to the nucleus. Reactive oxygen species produced by NADPH oxidase participated in this activation, mainly by the Nox4 subunit, ubiquitously expressed in all the compartments of HUVECs. Pravastatin inhibited ANG-induced MCP-1 production.

CONCLUSIONS

Our results support that ANG-induced MCP-1 production in HUVECs is mediated by AT2 instead AT1 receptor activation, which in turn activates NF-κB involving reactive oxygen species produced by the NADPH oxidase complex. Statins can also block ANG-induced MCP-1 production, probably by their inhibitory effects on NADPH oxidase activity.

The Nox1/4 Dual Inhibitor GKT137831 or Nox4 Knockdown Inhibits Angiotensin-II-Induced Adult Mouse Cardiac Fibroblast Proliferation and Migration. AT1 Physically Associates With Nox4

Both oxidative stress and inflammation contribute to chronic hypertension-induced myocardial fibrosis and adverse cardiac remodeling. Here we investigated whether angiotensin (Ang)-II-induced fibroblast proliferation and migration are NADPH oxidase (Nox) 4/ROS and IL-18 dependent. Our results show that the potent induction of mouse cardiac fibroblast (CF) proliferation and migration by Ang-II is markedly attenuated by Nox4 knockdown and the Nox inhibitor DPI. Further, Nox4 knockdown and DPI pre-treatment attenuated Ang-II-induced IL-18, IL-18Rα and collagen expression, and MMP9 and LOX activation. While neutralization of IL-18 blunted Ang-II-induced CF proliferation and migration, knockdown of MMP9 attenuated CF migration. The antioxidant NAC and the cell-permeable SOD mimetics Tempol, MnTBAP, and MnTMPyP attenuated oxidative stress and inhibited CF proliferation and migration. The Nox1/Nox4 dual inhibitor GKT137831 also blunted Ang-II-induced H2 O2 production and CF proliferation and migration. Further, AT1 bound Nox4, and Ang-II enhanced their physical association. Notably, GKT137831 attenuated the AT1/Nox4 interaction. These results indicate that Ang-II induces CF proliferation and migration in part via Nox4/ROS-dependent IL-18 induction and MMP9 activation, and may involve AT1/Nox4 physical association. Thus, either (i) neutralizing IL-18, (ii) blocking AT1/Nox4 interaction or (iii) use of the Nox1/Nox4 inhibitor GKT137831 may have therapeutic potential in chronic hypertension-induced adverse cardiac remodeling.