Angiotensin II modulates interleukin-1β-induced inflammatory gene expression in vascular smooth muscle cells via interfering with ERK-NF-κB crosstalk

New Dawn for Atherosclerosis: Vascular Endothelial Cell Senescence and Death

Endothelial cells (ECs) form the inner linings of blood vessels, and are directly exposed to endogenous hazard signals and metabolites in the circulatory system. The senescence and death of ECs are not only adverse outcomes, but also causal contributors to endothelial dysfunction, an early risk marker of atherosclerosis. The pathophysiological process of EC senescence involves both structural and functional changes and has been linked to various factors, including oxidative stress, dysregulated cell cycle, hyperuricemia, vascular inflammation, and aberrant metabolite sensing and signaling. Multiple forms of EC death have been documented in atherosclerosis, including autophagic cell death, apoptosis, pyroptosis, NETosis, necroptosis, and ferroptosis. Despite this, the molecular mechanisms underlying EC senescence or death in atherogenesis are not fully understood. To provide a comprehensive update on the subject, this review examines the historic and latest findings on the molecular mechanisms and functional alterations associated with EC senescence and death in different stages of atherosclerosis.

Characterization of a murine model of endothelial dysfunction induced by chronic intraperitoneal administration of angiotensin II

Endothelial dysfunction (ED) is a key factor for the development of cardiovascular diseases. Due to its chronic, life-threatening nature, ED only can be studied experimentally in animal models. Therefore, this work was aimed to characterize a murine model of ED induced by a daily intraperitoneal administration of angiotensin II (AGII) for 10 weeks. Oxidative stress, inflammation, vascular remodeling, hypertension, and damage to various target organs were evaluated in treated animals. The results indicated that a chronic intraperitoneal administration of AGII increases the production of systemic soluble VCAM, ROS and ICAM-1 expression, and the production of TNFα, IL1β, IL17A, IL4, TGFβ, and IL10 in the kidney, as well as blood pressure levels; it also promotes vascular remodeling and induces non-alcoholic fatty liver disease, glomerulosclerosis, and proliferative retinopathy. Therefore, the model herein proposed can be a representative model for ED; additionally, it is easy to implement, safe, rapid, and inexpensive.

Aging-Induced Impairment of Vascular Function: Mitochondrial Redox Contributions and Physiological/Clinical Implications

Significance: The vasculature responds to the respiratory needs of tissue by modulating luminal diameter through smooth muscle constriction or relaxation. Coronary perfusion, diastolic function, and coronary flow reserve are drastically reduced with aging. This loss of blood flow contributes to and exacerbates pathological processes such as angina pectoris, atherosclerosis, and coronary artery and microvascular disease. Recent Advances: Increased attention has recently been given to defining mechanisms behind aging-mediated loss of vascular function and development of therapeutic strategies to restore youthful vascular responsiveness. The ultimate goal aims at providing new avenues for symptom management, reversal of tissue damage, and preventing or delaying of aging-induced vascular damage and dysfunction in the first place. Critical Issues: Our major objective is to describe how aging-associated mitochondrial dysfunction contributes to endothelial and smooth muscle dysfunction via dysregulated reactive oxygen species production, the clinical impact of this phenomenon, and to discuss emerging therapeutic strategies. Pathological changes in regulation of mitochondrial oxidative and nitrosative balance (Section 1) and mitochondrial dynamics of fission/fusion (Section 2) have widespread effects on the mechanisms underlying the ability of the vasculature to relax, leading to hyperconstriction with aging. We will focus on flow-mediated dilation, endothelial hyperpolarizing factors (Sections 3 and 4), and adrenergic receptors (Section 5), as outlined in Figure 1. The clinical implications of these changes on major adverse cardiac events and mortality are described (Section 6). Future Directions: We discuss antioxidative therapeutic strategies currently in development to restore mitochondrial redox homeostasis and subsequently vascular function and evaluate their potential clinical impact (Section 7). Antioxid. Redox Signal. 35, 974-1015.

Quzhou Fructus Aurantii Extract suppresses inflammation via regulation of MAPK, NF-κB, and AMPK signaling pathway

The anti-inflammatory activity of Quzhou Fructus Aurantii Extract (QFAE) has been reported recently. Thus, present study aims to explore the mechanism of anti-inflammation of QFAE in vitro and in vivo to develop a lung phylactic agent. The anti-inflammatory mechanism of QFAE in RAW 264.7 cells and acute lung injury (ALI) mice model was determined by cytokines analysis, histopathological examination, Western blot assay, immunofluorescence, and immunohistochemistry analysis. The results showed that QFAE restrained mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways in LPS-induced RAW 264.7 cells, whereas AMP-activated protein kinase (AMPK) signaling pathways were activated, as revealed by prominent attenuation of phosphorylation of ERK, JNK, p38, p65, IκBα, RSK and MSK, and overt enhancement of phosphorylation of ACC and AMPKα. The levels of pro-inflammatory cytokines TNF, IL-6, and IL-1β were suppressed, whereas the level of anti-inflammatory cytokine IL-10 increased after pretreatment with QFAE in vivo and in vitro. Moreover, QFAE prevented mice from LPS-provoked ALI, bases on alleviating neutrophils, and macrophages in bronchoalveolar lavage fluid (BALF) and mitigatingpulmonary histological alters, as well as hematological change. The MAPK and NF-κB signaling pathways in LPS-stimulated ALI mice were dampened by QFAE pretreatment, whereas AMPK signaling pathways were accelerated, as testify by significant restraint of phosphorylation of ERK, JNK, p38, p65, and IκBα, and distinct elevation of phosphorylation of ACC and AMPKα. The remarkable anti-inflammatory effect of QFAE is associated with the suppression of MAPK and NF-κB signaling pathways and the initiation of AMPK signaling pathway.

Angiotensin II Causes Neuronal Damage in Stretch-Injured Neurons: Protective Effects of Losartan, an Angiotensin T1 Receptor Blocker

Angiotensin II (Ang II) is a mediator of oxidative stress via activation/induction of reactive oxygen and nitrogen species-generating enzymes, NADPH oxidase (NOX) and inducible nitric oxide synthase (iNOS). We investigated the hypothesis that overproduction of Ang II during traumatic brain injury (TBI) induces the activation of the oxidative stress, which triggers neuroinflammation and cell apoptosis in a cell culture model of neuronal stretch injury. We first established that stretch injury causes a rapid increase in the level of Ang II, which causes the release of pro-inflammatory cytokines, IL-1β and TNF-α, via the induction of oxidative stress. Since angiotensin-converting enzyme (ACE) mediates the production of Ang II via the conversion of Ang I into Ang II, we analyzed the expression of ACE by western blotting. Further, we analyzed caspase-3-mediated apoptosis by TUNEL staining and annexin V western blotting. Angiotensin type I (AT₁) receptor antagonist losartan attenuated Ang II-induced oxidative stress and associated neuroinflammation and cell death in cultured neurons. Remarkably, we noticed that the expression of Ang II type 1 receptor (AngT₁R) upregulated in neuronal stretch injury; losartan mitigates this upregulation. Findings from this study significantly extend our understanding of the pathophysiology of TBI and may have significant implications for developing therapeutic strategies for TBI-associated brain dysfunctions.

Analysis of Vascular Cell Response to Hypertension Induced by Pressure Loading and Its Application as a Tool for Exploring Pharmacological Modes of Action

Inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expression is induced by interleukin-1β (IL-1β) stimulation in vascular smooth muscle cells (VSMCs), resulting in the production of nitric oxide and prostaglandins such as PGI₂. The expression of iNOS and COX-2 in cultured VSMCs isolated from 6-7-week-old stroke-prone spontaneously hypertensive rats (SHRSP) is significantly lower than in cells of normotensive Wistar Kyoto rats (WKY). These reductions are also found in cells exposed to pulsatile atmospheric pressure between 80-160 mmHg at a rate of 4 cycles/min, which simulates systolic hypertension. Docosahexaenoic acid (DHA), an n-3 polyunsaturated fatty acid, potentiates IL-1β-induced iNOS and COX-2 expression in VSMCs isolated from WKY, but not those from SHRSP. In response to endothelial injury at a local site, iNOS and COX-2 induction in VSMCs may function primarily as a defensive and compensatory mechanism for endothelial dysfunction by preventing the development of pathological conditions. Thus, in certain pathological conditions associated with hypertension, vascular walls with reduced iNOS and COX-2 expression may aggravate or initiate further vascular injury. In this situation, DHA may contribute to maintaining homeostasis in VSMCs by potentiating iNOS and COX-2 expression. Using cells isolated from a genetic pathological animal model alongside cells exposed to experimental pathological conditions can be an effective tool for the analysis of cell response to hypertension and exploring pharmacological modes of action in vitro.

Oxidative stress and vascular inflammation in aging

Vascular aging, a determinant factor for cardiovascular disease and health status in the elderly, is now viewed as a modifiable risk factor. Impaired endothelial vasodilation is a early hallmark of arterial aging that precedes the clinical manifestations of vascular dysfunction, the first step to cardiovascular disease and influencing vascular outcomes in the elderly. Accordingly, the preservation of endothelial function is thought to be an essential determinant of healthy aging. With special attention on the effects of aging on the endothelial function, this review is focused on the two main mechanisms of aging-related endothelial dysfunction: oxidative stress and inflammation. Aging vasculature generates an excess of the reactive oxygen species (ROS), superoxide and hydrogen peroxide, that compromise the vasodilatory activity of nitric oxide (NO) and facilitate the formation of the deleterious radical, peroxynitrite. Main sources of ROS are mitochondrial respiratory chain and NADPH oxidases, although NOS uncoupling could also account for ROS generation. In addition, reduced antioxidant response mediated by erythroid-2-related factor-2 (Nrf2) and downregulation of mitochondrial manganese superoxide dismutase (SOD2) contributes to the establishment of chronic oxidative stress in aged vessels. This is accompanied by a chronic low-grade inflammatory phenotype that participates in defective endothelial vasodilation. The redox-sensitive transcription factor, nuclear factor-κB (NF-κB), is upregulated in vascular cells from old subjects and drives a proinflammatory shift that feedbacks oxidative stress. This chronic NF-κB activation is contributed by increased angiotensin-II signaling and downregulated sirtuins and precludes adequate cellular response to acute ROS generation. Interventions targeted to recover endogenous antioxidant capacity and cellular stress response rather than exogenous antioxidants could reverse oxidative stress-inflammation vicious cycle in vascular aging. Lifestyle attitudes such as caloric restriction and exercise training appear as effective ways to overcome defective antioxidant response and inflammation, favoring successful vascular aging and decreasing the risk for cardiovascular disease.

The Role of Mitogen-Activated Protein Kinase-Activated Protein Kinases (MAPKAPKs) in Inflammation

Mitogen-activated protein kinase (MAPK) pathways are implicated in several cellular processes including proliferation, differentiation, apoptosis, cell survival, cell motility, metabolism, stress response and inflammation. MAPK pathways transmit and convert a plethora of extracellular signals by three consecutive phosphorylation events involving a MAPK kinase kinase, a MAPK kinase, and a MAPK. In turn MAPKs phosphorylate substrates, including other protein kinases referred to as MAPK-activated protein kinases (MAPKAPKs). Eleven mammalian MAPKAPKs have been identified: ribosomal-S6-kinases (RSK1-4), mitogen- and stress-activated kinases (MSK1-2), MAPK-interacting kinases (MNK1-2), MAPKAPK-2 (MK2), MAPKAPK-3 (MK3), and MAPKAPK-5 (MK5). The role of these MAPKAPKs in inflammation will be reviewed.

ERK inhibition enhances TSA-induced gastric cancer cell apoptosis via NF-κB-dependent and Notch-independent mechanism

AIMS

To analyze the combined impact of the histone deacetylase inhibitor (HDACI) Trichostatin A (TSA) and the extracellular-signal-regulated kinase 1/2 (ERK1/2) inhibitor PD98059 on gastric cancer (GC) cell line SGC7901 growth.

MAIN METHODS

SGC7901 cells were treated with TSA, PD98059 or with a TSA-PD98059 combination. Effects of drug treatment on tumor cell proliferation, apoptosis, cell cycle progression, and cell signaling pathways were investigated by MTS assay, flow cytometry, Western blotting, chromatin immunoprecipitation (ChIP) assay, electrophoretic mobility shift assay (EMSA), and luciferase reporter assay, respectively.

KEY FINDINGS

PD98059 enhanced TSA-induced cell growth arrest, apoptosis and activation of p21(WAF1/CIP1), but reversed TSA-induced activation of ERK1/2 and nuclear factor-κB (NF-κB). TSA alone up-regulated Notch1 and Hes1, and down-regulated Notch2, but PD98059 did not affect the trends of Notch1 and Notch2 induced by TSA. Particularly, PD98059 did potentiate the ability of TSA to down-regulate phospho-histone H3 protein, but increased levels of the acetylated forms of histone H3 bound to the p21(WAF1/CIP1) promoter, leading to enhanced expression of p21(WAF1/CIP1) in SGC7901 cells.

SIGNIFICANCE

PD98059 synergistically potentiates TSA-induced GC growth arrest and apoptosis by manipulating NF-κB and p21(WAF1/CIP1) independent of Notch. Therefore, concomitant administration of HDACIs and ERK1/2 inhibitors may be a promising treatment strategy for individuals with GC.

Inflammation and metabolic dysfunction: links to cardiovascular diseases

Abdominal obesity is a major risk factor for cardiovascular disease, and recent studies highlight a key role of adipose tissue dysfunction, inflammation, and aberrant adipokine release in this process. An increased demand for lipid storage results in both hyperplasia and hypertrophy, finally leading to chronic inflammation, hypoxia, and a phenotypic change of the cellular components of adipose tissue, collectively leading to a substantially altered secretory output of adipose tissue. In this review we have assessed the adipo-vascular axis, and an overview of adipokines associated with cardiovascular disease is provided. This resulted in a first list of more than 30 adipokines. A deeper analysis only considered adipokines that have been reported to impact on inflammation and NF-κB activation in the vasculature. Out of these, the most prominent link to cardiovascular disease was found for leptin, TNF-α, adipocyte fatty acid-binding protein, interleukins, and several novel adipokines such as lipocalin-2 and pigment epithelium-derived factor. Future work will need to address the potential role of these molecules as biomarkers and/or drug targets.