Inhibition of endothelial vascular cell adhesion molecule-1 expression by nitric oxide involves the induction and nuclear translocation of IkappaBalpha

[Immunomodulation by nutritional intervention in critically ill patients]

Critically ill patients often suffer from a complex and severe immunological dysfunction. The differentiation and function of human immune cells are fundamentally controlled through metabolic processes. New concepts of immunonutrition therefore try to use enteral and parenteral nutrition to positively impact on the immune function of intensive care unit patients. This review article concisely presents the currently available evidence on the commonly used isolated supplements (anti-oxidative substances, amino acids, essential fatty acids) and difficulties related to their clinical use. The second part presents new and more comprehensive concepts of immunonutrition to influence the intestinal microbiome and to modulate the macronutrient composition. Immunonutrition of critically ill patients bears enormous potential and could become a valuable clinical tool for modulation of the immunometabolism of intensive care unit patients.

The Role of Sildenafil in Treating Brain Injuries in Adults and Neonates

Sildenafil is a recognized treatment for patients suffering from erectile dysfunction and pulmonary hypertension. However, new evidence suggests that it may have a neuroprotective and a neurorestorative role in the central nervous system of both adults and neonates. Phosphodiesterase type 5-the target of sildenafil-is distributed in many cells throughout the body, including neurons and glial cells. This study is a comprehensive review of the demonstrated effects of sildenafil on the brain with respect to its function, extent of injury, neurons, neuroinflammation, myelination, and cerebral vessels.

Intracellular and extracelluar cyclic GMP in the brain and the hippocampus

Cyclic Guanosine-Monophosphate (cGMP) is implicated as second messenger in a plethora of pathways and its effects are executed mainly by cGMP-dependent protein kinases (PKG). It is involved in both peripheral (cardiovascular regulation, intestinal secretion, phototransduction, etc.) and brain (hippocampal synaptic plasticity, neuroinflammation, cognitive function, etc.) processes. Stimulation of hippocampal cGMP signaling have been proved to be beneficial in animal models of aging, Alzheimer's disease or hepatic encephalopathy, restoring different cognitive functions such as passive avoidance, object recognition or spatial memory. However, even when some inhibitors of cGMP-degrading enzymes (PDEs) are already used against peripheral pathologies, their utility as neurological treatments is still under clinical investigation. Additionally, it has been demonstrated a list of cGMP roles as not second but first messenger. The role of extracellular cGMP has been specially studied in hippocampal function and cognitive impairment in animal models and it has emerged as an important modulator of neuroinflammation-mediated cognitive alterations and hippocampal synaptic plasticity malfunction. Specifically, it has been demonstrated that extracellular cGMP decreases hippocampal IL-1β levels restoring membrane expression of glutamate receptors in the hippocampus and cognitive function in hyperammonemic rats. The mechanisms implicated are still unclear and might involve complex interactions between hippocampal neurons, astrocytes and microglia. Membrane targets for extracellular cGMP are still poorly understood and must be addressed in future studies.

Mechanosensitive molecular interactions in atherogenic regions of the arteries: development of atherosclerosis

A terrible disease of the cardiovascular system, atherosclerosis, develops in the areas of bends and branches of arteries, where the direction and modulus of the blood flow velocity vector change, and consequently so does the mechanical effect on endothelial cells in contact with the blood flow. The review focuses on topical research studies on the development of atherosclerosis – mechanobiochemical events that transform the proatherogenic mechanical stimulus of blood flow – low and low/oscillatory arterial wall shear stress in the chains of biochemical reactions in endothelial cells, leading to the expression of specific proteins that cause the progression of the pathological process. The stages of atherogenesis, systemic risk factors for atherogenesis and its important hemodynamic factor, low and low/oscillatory wall shear stress exerted by blood flow on the endothelial cells lining the arterial walls, have been described. The interactions of cell adhesion molecules responsible for the development of atherosclerosis under low and low/oscillating shear stress conditions have been demonstrated. The activation of the regulator of the expression of cell adhesion molecules, the transcription factor NF-κB, and the factors regulating its activation under these conditions have been described. Mechanosensitive signaling pathways leading to the expression of NF-κB in endothelial cells have been described. Studies of the mechanobiochemical signaling pathways and interactions involved in the progression of atherosclerosis provide valuable information for the development of approaches that delay or block the development of this disease. Key words: atherogenesis; shear stress; transcription factor NF-κB; RelA expression; mechanosensitive receptors; cell adhesion molecules; signaling pathways; mechanotransduction.

Nutrient regulation of inflammatory signalling in obesity and vascular disease

Despite obesity and diabetes markedly increasing the risk of developing cardiovascular diseases, the molecular and cellular mechanisms that underlie this association remain poorly characterised. In the last 20 years it has become apparent that chronic, low-grade inflammation in obese adipose tissue may contribute to the risk of developing insulin resistance and type 2 diabetes. Furthermore, increased vascular pro-inflammatory signalling is a key event in the development of cardiovascular diseases. Overnutrition exacerbates pro-inflammatory signalling in vascular and adipose tissues, with several mechanisms proposed to mediate this. In this article, we review the molecular and cellular mechanisms by which nutrients are proposed to regulate pro-inflammatory signalling in adipose and vascular tissues. In addition, we examine the potential therapeutic opportunities that these mechanisms provide for suppression of inappropriate inflammation in obesity and vascular disease.

Nitric Oxide and Immune Responses in Cancer: Searching for New Therapeutic Strategies

In recent years, there has been an increasing interest in understanding the mysterious functions of nitric oxide (NO) and how this pleiotropic signaling molecule contributes to tumorigenesis. This review attempts to expose and discuss the information available on the immunomodulatory role of NO in cancer and recent approaches to the role of NO donors in the area of immunotherapy. To address the goal, the following databases were searched to identify relevant literature concerning empirical evidence: The Cochrane Library, Pubmed, Medline, EMBASE from 1980 through March 2020. Valuable attempts have been made to develop distinctive NO-based cancer therapy. Although the data do not allow generalization, the evidence seems to indicate that low / moderate levels may favor tumorigenesis while higher levels would exert anti-tumor effects. In this sense, the use of NO donors could have an important therapeutic potential within immunotherapy, although there are still no clinical trials. The emerging understanding of NO-regulated immune responses in cancer may help unravel the recent features of this "double-edged sword" in cancer physiological and pathologic processes and its potential use as a therapeutic agent for cancer treatment. In short, in this review, we discuss the complex cellular mechanism in which NO, as a pleiotropic signaling molecule, participates in cancer pathophysiology. We also debate the dual role of NO in cancer and tumor progression, and clinical approaches for inducible nitric oxide synthase (iNOS) based therapy against cancer.

Cellular response to chemicals present in air pollution in occupationally exposed workers and its potential cancer susceptibility

The study aimed to evaluate the potential effects of the chronic exposure to chemical agents from air pollution on phenotypic and genotypic expressions of peripheral biomarkers and tumor-related proteins in mononuclear cells. This study evaluates 85 taxi drivers (outdoor workers) and 55 non-occupationally exposed persons (NOE) to air pollution (indoor workers). The biomarkers were urinary 1-hydroxypyrene (1-OHP), for organic agents, and blood As and Ni, for inorganic agents. Oxidative stress biomarkers; protein expression of ICAM-1 (CD54), β2-integrin, L-selectin (CD62-L), and MCP1; gene expression of ICAM-1, p53 and CD26 were performed. Urinary 1-OHP and blood As and Ni levels were increased in taxi drivers and were associated with inflammatory and oxidative stress biomarkers. These exposure biomarkers were also associated with each other, suggesting a common source of exposure. The gene expression of p53, CD26 and ICAM-1 were decreased in taxi drivers and were strongly associated between them, indicating a commom regulation point. The antioxidant non-protein thiols and lycopene were negatively associated with inflammatory biomarkers, maybe regulating the immune-response. We demonstrated, for the first time, that in occupational exposure to air pollution chemicals, oxidative and inflammatory processes are involved in the immune-regulatory process, and indirectly contribute to suppressing the p53 and CD26 expressions, increasing the risk of cancer development. On the other hand, antioxidants could contribute to improving the immune-regulation, but more studies are needed.

Disturbed flow-induced Gs-mediated signaling protects against endothelial inflammation and atherosclerosis

Atherosclerosis develops preferentially in areas of the arterial system, in which blood flow is disturbed. Exposure of endothelial cells to disturbed flow has been shown to induce inflammatory signaling, including NF-κB activation, which leads to the expression of leukocyte adhesion molecules and chemokines. Here, we show that disturbed flow promotes the release of adrenomedullin from endothelial cells, which in turn activates its G_s-coupled receptor calcitonin receptor–like receptor (CALCRL). This induces antiinflammatory signaling through cAMP and PKA, and it results in reduced endothelial inflammation in vitro and in vivo. Suppression of endothelial expression of Gα_s, the α subunit of the G-protein G_s; CALCRL; or adrenomedullin leads to increased disturbed flow–induced inflammatory signaling in vitro and in vivo. Furthermore, mice with induced endothelial-specific deficiency of Gα_s, CALCRL, or adrenomedullin show increased atherosclerotic lesions. Our data identify an antiinflammatory signaling pathway in endothelial cells stimulated by disturbed flow and suggest activation of the endothelial adrenomedullin/CALCRL/G_s system as a promising approach to inhibit progression of atherosclerosis.

Disturbed flow promotes the release of adrenomedullin from endothelial cells and activates Gs-mediated signaling, which reduces endothelial inflammation in vitro and in vivo.

Role of Melanin Chemiexcitation in Melanoma Progression and Drug Resistance

Melanoma is the deadliest type of skin cancer. Human melanomas often show hyperactivity of nitric oxide synthase (NOS) and NADPH oxidase (NOX), which, respectively, generate nitric oxide (NO ^· ) and superoxide (O₂ ^·- ). The NO ^· and O₂ ^- react instantly with each other to generate peroxynitrite (ONOO^-) which is the driver of melanin chemiexcitation. Melanoma precursors, the melanocytes, are specialized skin cells that synthesize melanin, a potent shield against sunlight's ultraviolet (UV) radiation. However, melanin chemiexcitation paradoxically demonstrates the melanomagenic properties of melanin. In a loop, the NOS activity regulates melanin synthesis, and melanin is utilized by the chemiexcitation pathway to generate carcinogenic melanin-carbonyls in an excited triplet state. These carbonyl compounds induce UV-specific DNA damage without UV. Additionally, the carbonyl compounds are highly reactive and can make melanomagenic adducts with proteins, DNA and other biomolecules. Here we review the role of the melanin chemiexcitation pathway in melanoma initiation, progression, and drug resistance. We conclude by hypothesizing a non-classical, positive loop in melanoma where melanin chemiexcitation generates carcinogenic reactive carbonyl species (RCS) and DNA damage in normal melanocytes. In parallel, NOS and NOX regulate melanin synthesis generating raw material for chemiexcitation, and the resulting RCS and reactive nitrogen species (RNS) regulate cellular proteome and transcriptome in favor of melanoma progression, metastasis, and resistance against targeted therapies.

Nitroxyl: A Novel Strategy to Circumvent Diabetes Associated Impairments in Nitric Oxide Signaling

Diabetes is associated with an increased mortality risk due to cardiovascular complications. Hyperglycemia-induced oxidative stress underlies these complications, leading to an impairment in endogenous nitric oxide (NO•) generation, together with reductions in NO• bioavailability and NO• responsiveness in the vasculature, platelets and myocardium. The latter impairment of responsiveness to NO•, termed NO• resistance, compromises the ability of traditional NO•-based therapeutics to improve hemodynamic status during diabetes-associated cardiovascular emergencies, such as acute myocardial infarction. Whilst a number of agents can ameliorate (e.g. angiotensin converting enzyme [ACE] inhibitors, perhexiline, statins and insulin) or circumvent (e.g. nitrite and sGC activators) NO• resistance, nitroxyl (HNO) donors offer a novel opportunity to circumvent NO• resistance in diabetes. With a suite of vasoprotective properties and an ability to enhance cardiac inotropic and lusitropic responses, coupled with preserved efficacy in the setting of oxidative stress, HNO donors have intact therapeutic potential in the face of diminished NO• signaling. This review explores the major mechanisms by which hyperglycemia-induced oxidative stress drives NO• resistance, and the therapeutic potential of HNO donors to circumvent this to treat cardiovascular complications in type 2 diabetes mellitus.

Arctium lappa root extract containing L-arginine prevents TNF-α-induced early atherosclerosis in vitro and in vivo

Atherosclerosis is a chronic inflammatory disease affecting the aorta and is a major cause of cardiovascular disease. Arctium lappa root is a plant widely used in traditional Chinese medicine (TCM), and Arctium lappa root extract (ALE) has been reported to exhibit anti-inflammatory capacity and to ameliorate endothelial dysfunction. Thus, we hypothesized that ALE would inhibit the early atherosclerotic stage. In this study, we evaluated the inhibitory effect of ALE on early arteriosclerosis and its mechanisms of action. ALE suppressed TNF-α-induced monocyte adhesion to the vascular endothelium by suppressing NF-κB signaling in HUVECs. In an acute mouse model of atherosclerosis, ALE suppressed TNF-α-induced monocyte infiltration of the vascular endothelium and the expression of genes encoding inflammatory cytokines including IL-1β, IL-6, TNF-α, and MCP-1 in the mouse aorta. Moreover, inulin-type fructan and amino acids, especially L-aspartate and L-arginine (60.27 and 42.17 mg/g, respectively) were detected by NMR, MALDI-TOF MS, and HPLC analysis as the main components of ALE. Notably, L-arginine suppressed TNF-α-induced monocyte adhesion to HUVECs. Therefore, these results suggest that ALE may be a functional food for the suppression or prevention of early stages of atherosclerosis.

Proteomic and transcriptomic changes in rat liver following oral feeding of formaldehyde

Formaldehyde (FA), a ubiquitous volatile organic compound present in a wide range of resources, is a hazardous chemical and human carcinogen. Contamination of FA in food, especially perishable commodities like fish and meat, is a major source of exposure, although it is not recommended for use in food and food products owing to its carcinogenicity. Effects of oral feeding of FA have been studied by evaluating general health, haematology and clinical chemistry in rat. Recent studies have shown that FA exposure leads to detrimental cardiovascular effects. It regulates vascular tensions through nitric oxide-cGMP signalling pathway and ion channels in rats. Although FA is an established carcinogen, molecular studies on carcinogenic potential with dose dependency are meagre. In this context, the present study was undertaken to investigate the toxicogenomic and proteomic alterations in liver of rats fed FA through drinking water. By proteomic analysis, 621 proteins/protein-subunits showed differential abundance (proteome data available via ProteomeXchange with identifier PXD010534), whereas 536 differentially-expressed-genes were identified by transcriptome analysis (data available via Sequence Read Archive with identifier SRR7974113). Gene ontology analysis showed that binding, catalysis, signal transduction were affected in formaldehyde-fed rats. Pathway analysis revealed that formaldehyde-exposure activated PI3K-AKT pathway that leads to inhibition of caspase activity thereby assisting cells to survive against apoptosis. Decreased abundance/down-regulation of ANGPT, eNOS, STAT3 proteins/transcripts and increased abundance of EDN1 indicated decrease in angiogenesis and vasodilatation that restricted hepatic cells from becoming tumorigenic; thus, indicating FA could be less toxic and non-tumorigenic at low concentrations.

Inflammation in Hypertension

For more than 50 years, evidence has accumulated that inflammation contributes to the pathogenesis of hypertension. Immune cells have been observed in vessels and kidneys of hypertensive humans. Biomarkers of inflammation, including high sensitivity C-reactive protein, various cytokines, and products of the complement pathway are elevated in humans with hypertension. Emerging evidence suggests that hypertension is accompanied and indeed initiated by activation of complement, the inflammasome, and by a change in the phenotype of circulating immune cells, particularly myeloid cells. High-dimensional transcriptomic analyses are providing insight into new subclasses of immune cells that are likely injurious in hypertension. These inflammatory events are interdependent and there is ultimately engagement of the adaptive immune system through mechanisms involving oxidative stress, modification of endogenous proteins, and alterations in antigen processing and presentation. These observations suggest new therapeutic opportunities to reduce end organ damage in hypertension might be used and guided by levels of inflammatory biomarkers.

Molecular Mechanisms of Nitric Oxide in Cancer Progression, Signal Transduction, and Metabolism

SIGNIFICANCE

Cancer is a complex disease, which not only involves the tumor but its microenvironment comprising different immune cells as well. Nitric oxide (NO) plays specific roles within tumor cells and the microenvironment and determines the rate of cancer progression, therapy efficacy, and patient prognosis. Recent Advances: Key understanding of the processes leading to dysregulated NO flux within the tumor microenvironment over the past decade has provided better understanding of the dichotomous role of NO in cancer and its importance in shaping the immune landscape. It is becoming increasingly evident that nitric oxide synthase 2 (NOS2)-mediated NO/reactive nitrogen oxide species (RNS) are heavily involved in cancer progression and metastasis in different types of tumor. More recent studies have found that NO from NOS2⁺ macrophages is required for cancer immunotherapy to be effective.

CRITICAL ISSUES

NO/RNS, unlike other molecules, are unique in their ability to target a plethora of oncogenic pathways during cancer progression. In this review, we subcategorize the different levels of NO produced by cells and shed light on the context-dependent temporal effects on cancer signaling and metabolic shift in the tumor microenvironment.

FUTURE DIRECTIONS

Understanding the source of NO and its spaciotemporal profile within the tumor microenvironment could help improve efficacy of cancer immunotherapies by improving tumor infiltration of immune cells for better tumor clearance.

L-sepiapterin restores SLE serum-induced markers of endothelial function in endothelial cells

OBJECTIVE

SLE serves as an independent risk factor` for endothelial dysfunction (ED) not explained by Framingham risk factors. We sought to understand the development of SLE-induced ED on a cellular level in order to develop strategies aimed at reversing cellular abnormalities. This study assessed the impact of SLE patient serum on endothelial nitric oxide synthase (eNOS), nitric oxide (NO) production and functional changes in the cell.

METHODS

Human umbilical vein endothelial cells (HUVECs) cultured in serum of either SLE (n=25) or healthy patients (n=14) or endothelial basal medium 2 (EBM-2) culture media supplemented with fetal bovine serum with or without L-sepiapterin were used for our studies. We applied the fluorescent probe DAF-FM diacetate for intracellular NO detection using flow cytometry. Total RNA isolates were analysed using reverse transcription PCR for eNOS mRNA expression. Oxygen consumption rate was determined using seahorse analysis. Neutrophil adhesion and migration were determined using a calcein AM microscopy assay.

RESULTS

The mRNA expression of eNOS was increased in SLE cultured HUVECs compared with healthy control (p<0.05). The SLE eNOS mRNA level correlated with SLE patient age (p=0.008); however, this trend was not observed with healthy patients. SLE serum reduced NO production in HUVECs compared with EBM-2 cultured cells (p<0.05). Co-treatment of endothelial cells with L-sepiapterin preserved HUVEC capacity to produce NO in SLE conditions (p<0.01). SLE serum enhanced neutrophil migration (p<0.01) but not neutrophil adhesion compared with healthy controls. The bioenergetic health index was not different.

CONCLUSIONS

SLE likely causes disruption of endothelial cell eNOS function and NO modulated pathways.

Inhibitory effects of sildenafil and tadalafil on inflammation, oxidative stress and nitrosative stress in animal model of bronchial asthma

BACKGROUND

Cyclic neucleotides are involved in many cellular functions including smooth muscle relaxation, inflammation, and signal transduction. Sildenafil and tadalafil are phosphodiesterase-5 (PDE-5) inhibitors which prevent the degradation of cyclic neucleotide i.e. guanosine 3',5' cyclic monophosphate (cGMP) and increase the levels of cGMP. In this study sildenafil and tadalafil were evaluated for their anti-inflammatory, anti-oxidative and anti-nitrosative stress potential in animal model of bronchial asthma.

METHODS

Wistar rats were sensitized with 10 mg intraperitoneal (ip) ovalbumin adsorbed to 10 μg of aluminum hydroxide on day 0. Animals were given sildenafil (1 and 3 mg/kg ip) and tadalafil (1 and 3 mg/kg ip) from day 1 to day 14. Also, on day 14 animals were challenged with ovalbumin (1 mg ip). After 24 h, samples were collected to analyze interleukin-4 (IL-4) and tumour necrosis factor-α (TNF-α), in serum and bronchoalveolar lavage fluid (BALF). The oxidative stress markers malondialdehyde (MDA), reduced glutathione (GSH) and nitric oxide metabolites (NO_x) were also measured in serum.

RESULTS

Pre-treatment with sildenafil (1 and 3 mg/kg ip) and tadalafil (1 and 3 mg/kg ip) significantly reduced the levels of pro-inflammatory cytokines IL-4 and TNF-α in rat serum and BALF. In addition, pre-treatment with both the drugs decreased the levels of MDA and NO_x and increased the levels of GSH in serum.

CONCLUSIONS

Sildenafil and tadalafil decreased pro-inflammatory cytokines in serum and BALF. Both drugs inhibit oxidative and nitrosative stress in animal model of bronchial asthma and could have a therapeutic potential in bronchial asthma.

Anti-inflammatory Role of Carotenoids in Endothelial Cells Derived from Umbilical Cord of Women Affected by Gestational Diabetes Mellitus

Diabetes is associated with vascular inflammation, endothelial dysfunction, and oxidative stress, promoting the development of cardiovascular diseases (CVD). Several studies showed that a carotenoid-rich diet is associated to a reduced cardiovascular risk in healthy and diabetic subjects, although the mechanisms of action are still unknown. Here, the potential role of β-carotene (BC) and lycopene (Lyc) in human endothelial cells isolated from human umbilical cord vein (HUVECs) of women with gestational diabetes (GD) and respective controls (C) has been investigated. Results showed that BC and Lyc reduced the tumor necrosis factor alpha- (TNF-α-) stimulated monocyte-endothelium interaction (adhesion assay), membrane exposure (flow cytometry), and total expression levels (Western blot) of VCAM-1 and ICAM-1 in both cell types. Moreover, the treatment with BC and Lyc reduced the TNF-α-induced nuclear translocation of NF-κB (image flow cytometry) by preserving bioavailability of nitric oxide (NO, flow cytometry, and cGMP EIA kit assay), a key vasoactive molecule. Notably, BC and Lyc pretreatment significantly reduced peroxynitrite levels (flow cytometry), contributing to the redox balance protection. These results suggest a new mechanism of action of carotenoids which exert vascular protective action in diabetic condition, thus reinforcing the importance of a carotenoid-rich diet in the prevention of diabetes cardiovascular complications.

Regulation of Cell Survival, Apoptosis, and Epithelial-to-Mesenchymal Transition by Nitric Oxide-Dependent Post-Translational Modifications

SIGNIFICANCE

Nitric oxide (NO) is a physiopathological messenger generating different reactive nitrogen species (RNS) according to hypoxic, acidic and redox conditions. Recent Advances: RNS and reactive oxygen species (ROS) promote relevant post-translational modifications, such as nitrosation, nitration, and oxidation, in critical components of cell proliferation and death, epithelial-to-mesenchymal transition, and metastasis.

CRITICAL ISSUES

The pro- or antitumoral properties of NO are dependent on local concentration, redox state, cellular status, duration of exposure, and compartmentalization of NO generation. The increased expression of NO synthase has been associated with cancer progression. However, the experimental strategies leading to high intratumoral NO generation have been shown to exert antitumoral properties. The effect of NO and ROS on cell signaling is critically altered by factors modulating tumor progression such as oxygen content, metabolism, and inflammatory response. The review describes the alteration of key components involved in cell survival and death, metabolism, and metastasis induced by RNS- and ROS-related post-translational modifications.

FUTURE DIRECTIONS

The identification of the molecular targets affected by nitrosation, nitration, and oxidation, as well as their interactions with other post-translational modifications, will improve the understanding on the complex signaling and cell fate decision in cancer. The therapeutic NO-based strategies have to address the complex crosstalk among NO and ROS with regard to critical components affecting tumor cell survival, metabolism, and metastasis in the progression of cancer, as well as close interaction with ionizing radiation and chemotherapy.

Circulating low density lipoprotein (LDL)

Low-density lipoprotein (LDL) particles are known as atherogenic agents in coronary artery diseases. They modify to other electronegative forms and may be the subject for improvement of inflammatory events in vessel subendothelial spaces. The circulating LDL value is associated with the plasma PCSK-9 level. They internalize into macrophages using the lysosomal receptor-mediated pathways. LDL uptake is related to the membrane scavenger receptors, modifications of lipid and protein components of LDL particles, vesicular maturation and lipid stores of cells. Furthermore, LDL vesicular trafficking is involved with the function of some proteins such as Rab and Lamp families. These proteins also help in the transportation of free cholesterol from lysosome into the cytosol. The aggregation of lipids in the cytosol is a starting point for the formation of foam cells so that they may participate in the primary core of atherosclerosis plaques. The effects of macrophage subclasses are different in the formation and remodeling of plaques. This review is focused on the cellular and molecular events involved in cholesterol homeostasis.

Ablation of Tacr2 in mice leads to gastric emptying disturbance

BACKGROUND

Tacr2 is one of the G protein-coupled receptors(GPCRs) that mediate the biological actions of tachykinins. It is abundantly expressed in the gastrointestinal (GI) system and is thought to play an important role in GI motility, secretion, and visceral sensitivity. Previously, the physiological and pathophysiological functions of Tacr2 were mainly studied using Tacr2 selective agonists or antagonists. Here, we seek to investigate the effect of Tacr2 disruption in mice to provide further insights.

METHODS

The Tacr2 knockout mice were generated by homologous recombination and the phenotypic changes of the Tacr2-null mice were analyzed and compared with their wild type (wt) littermates.

KEY RESULTS

Increased food retention was detected in Tacr2^-/- mice. The stomach of Tacr2^-/- mice had thinner muscularis externa and less neurons in the myenteric plexus. The stomach and small intestine exhibited longer duration of electrical field stimulation (EFS)-induced inhibition in the gastric fundus and decreased frequency of migrating motor complex (MMC), respectively. Neuronal nitric oxide synthase (nNOS) and vasoactive intestinal polypeptide (VIP) were significantly up-regulated due to Tarc2 deficiency, contributing to enhanced nitric oxide (NO) signaling in the stomach of Tacr2^-/- mice. Intraperitoneal application of 7-nitroindazole (7-NI) to Tacr2^-/- mice effectively relieved the gastric emptying disturbance. Moreover, Creb and NF-κB signalings were involved in the regulation of these physiological changes initiated by Tacr2 deficiency.

CONCLUSIONS & INFERENCES

Tacr2 negatively regulated the expression of nNOS and VIP both in vivo and in vitro. Its ablation in mice elevated the expression of nNOS and VIP, enhanced NO signaling and changed the Creb and NF-κB signalings, finally leading to the gastric emptying disturbance of Tacr2^-/- mice.

Cavin-1 regulates caveolae-mediated LDL transcytosis: crosstalk in an AMPK/eNOS/ NF-κB/Sp1 loop

Caveolae are specialized lipid rafts structure in the cell membrane and critical for regulating endothelial functions, e.g. transcytosis of macromolecules like low density lipoprotein (LDL) etc. Specifically, the organization and functions of caveolae are mediated by structure protein (caveolin-1) and adapter protein (cavin-1). The pathogenic role of caveolin-1 is well studied; nevertheless, mechanisms whereby cavin-1 regulates signaling transduction remain poorly understood. The aim of this study was designed to explore the role of cavin-1 in caveolae-mediated LDL transcytosis across endothelial cells. We reported here that cavin-1 knockdown mediated by small interfering RNA (siRNA) caused a significant decrease of LDL transcytosis. Moreover, cavin-1 knockdown increased the activity of endothelial nitric oxide synthase (eNOS) and the production of nitric oxide (NO). Consequently, an eNOS inhibitor, N-Nitro-L-Arginine Methyl Ester (L-NAME), not only suppressed the activity of specificity protein (Sp1) and nuclear factor kappa B (NF-κB), but also inhibited both activities via activating adenosine 5‘-monophosphate- activated protein kinase (AMPK). In conclusion, we proposed an AMPK/eNOS/NF-κB/Sp1 circuit loop was formed to regulate caveolae residing proteins’ expression, e.g. LDL receptor (LDLR), caveolin-1, eNOS, thereby to regulate caveolae-mediated LDL transcytosis in endothelial cells.

AMP-Activated Protein Kinase: An Ubiquitous Signaling Pathway With Key Roles in the Cardiovascular System

The AMP-activated protein kinase (AMPK) is a key regulator of cellular and whole-body energy homeostasis, which acts to restore energy homoeostasis whenever cellular energy charge is depleted. Over the last 2 decades, it has become apparent that AMPK regulates several other cellular functions and has specific roles in cardiovascular tissues, acting to regulate cardiac metabolism and contractile function, as well as promoting anticontractile, anti-inflammatory, and antiatherogenic actions in blood vessels. In this review, we discuss the role of AMPK in the cardiovascular system, including the molecular basis of mutations in AMPK that alter cardiac physiology and the proposed mechanisms by which AMPK regulates vascular function under physiological and pathophysiological conditions.

Roles of Vascular Oxidative Stress and Nitric Oxide in the Pathogenesis of Atherosclerosis

Major reactive oxygen species (ROS)–producing systems in vascular wall include NADPH (reduced form of nicotinamide adenine dinucleotide phosphate) oxidase, xanthine oxidase, the mitochondrial electron transport chain, and uncoupled endothelial nitric oxide (NO) synthase. ROS at moderate concentrations have important signaling roles under physiological conditions. Excessive or sustained ROS production, however, when exceeding the available antioxidant defense systems, leads to oxidative stress. Animal studies have provided compelling evidence demonstrating the roles of vascular oxidative stress and NO in atherosclerosis. All established cardiovascular risk factors such as hypercholesterolemia, hypertension, diabetes mellitus, and smoking enhance ROS generation and decrease endothelial NO production. Key molecular events in atherogenesis such as oxidative modification of lipoproteins and phospholipids, endothelial cell activation, and macrophage infiltration/activation are facilitated by vascular oxidative stress and inhibited by endothelial NO. Atherosclerosis develops preferentially in vascular regions with disturbed blood flow (arches, branches, and bifurcations). The fact that these sites are associated with enhanced oxidative stress and reduced endothelial NO production is a further indication for the roles of ROS and NO in atherosclerosis. Therefore, prevention of vascular oxidative stress and improvement of endothelial NO production represent reasonable therapeutic strategies in addition to the treatment of established risk factors (hypercholesterolemia, hypertension, and diabetes mellitus).

Effect of Thyrotropin on Osteopontin, Integrin αvβ3, and VCAM-1 in the Endothelium via Activation of Akt

Numerous epidemiological studies have shown that subclinical hypothyroidism (SCH) can impair endothelial function and cause dyslipidemia. Studies have evaluated the effects of thyroid stimulating hormone (TSH) on endothelial cells, but the mechanism underlying the proatherosclerotic effect of increased TSH levels remains unclear. In the present study, SCH rat models were established in thyroidectomized Wistar rats that were given l-T₄ daily. The results showed that in vivo, the expression of osteopontin (OPN) vascular cell adhesion molecule (VCAM-1), and levels of integrin α_vβ₃ in the aortic tissue in SCH and Hypothyroidism (CH) groups was higher than in the control group. However, the effect in the SCH group was higher than in the CH group. In vitro, results showed that different concentration and time gradients of TSH stimulation could increase the expression of OPN, VCAM-1, and integrin α_vβ₃, and this was accompanied by extracellular signal regulated kinase 1/2 (Erk1/2) and Akt activation in human umbilical vein endothelial cells (HUVECs). TSH induced elevation of these proatherosclerotic factors was partially suppressed by a specific Akt inhibitor but not by a specific Erk inhibitor. Findings suggested that the endothelial dysfunction caused by SCH was related to increased proatherosclerotic factors induced by TSH via Akt activation.

S-nitrosocaptopril interrupts adhesion of cancer cells to vascular endothelium by suppressing cell adhesion molecules via inhibition of the NF-кB and JAK/STAT signal pathways in endothelial cells

Inflammatory cytokines can induce the expression of cell adhesion molecules (CAMs) in endothelial cells. The induction may play an important role in attracting circulating tumor cells (CTCs) to endothelial cells. S-nitrosocaptopril (CapNO) is known to produce vasorelaxation and interfere the hetero-adhesion of CTCs to vascular endothelium via down-regulating the expression of CAMs. To elucidate the mechanisms underlying the inhibition of CapNO on CAMs, in this study, we examined the relationship between cytokines and CAMs expression and investigated the effects of CapNO on cytokine-induced NF-кB and JAK/STAT signal pathways. The activation of CAMs by cytokines was dependent on concentrations and reaction time of cytokines, and the combination of cytokines could produce a strong synergistic effect. IL-1β induced the expression of CAMs on endothelial cells by activating NF-кB and JAK/STAT pathways. CapNO inhibited IL-1β-stimulated NF-кB pathway by down-regulating IKK-α and inducing IкB-α directly. CapNO also inhibited JAK/STAT pathway by inhibiting JAK2 and STAT3 expressions. These effects bring about down-regulating CAMs expression on endothelial cells. These results suggest that CapNO may interrupt adhesion of cancer cells to endothelium by suppressing CAMs via inhibiting the NF-кB and JAK/STAT pathways in endothelial cells.

Macrophage-derived nitric oxide initiates T-cell diapedesis and tumor rejection

In tumor biology, nitric oxide (NO) is generally regarded as an immunosuppressive molecule that impedes T-cell functions and activation of endothelial cells. Contrasting with this view, we here describe a critical role for NO derived from inducible nitric oxide (iNOS)-expressing tumor macrophages in T-cell infiltration and tumor rejection as shown by iNOS gene deletion, inhibition of iNOS, or NO donors. Specifically, macrophage-derived NO was found to induce on tumor vessels adhesion molecules that were required for T-cell extravasation. Experiments with human endothelial cells revealed a bimodal dose-dependent effect of NO. High doses of NO donors were indeed suppressive but lower, more physiological concentrations, induced adhesion molecules in an NFkB-dependent pathway and preferentially activated transcription of genes involved in lymphocyte diapedesis. iNOS⁺ macrophages in tumors appear to generate precisely the amount of NO that promotes endothelial activation and T-cell infiltration. These results will be valuable for the development of strategies designed to overcome the paucity of T-cell infiltration into tumors that is a major obstacle in clinical cancer immunotherapy.

Nitroxyl (HNO) reduces endothelial and monocyte activation and promotes M2 macrophage polarization

In the present study, the effect of nitroxyl anion (HNO) donors on factors that precede atherosclerosis was examined. They reduced endothelial cell inflammation and monocyte activation and as such may be an effective treatment for coronary artery disease.

Delta- and gamma-tocotrienol isomers are potent in inhibiting inflammation and endothelial activation in stimulated human endothelial cells

Background

Tocotrienols (TCTs) are more potent antioxidants than α-tocopherol (TOC). However, the effectiveness and mechanism of the action of TCT isomers as anti-atherosclerotic agents in stimulated human endothelial cells under inflammatory conditions are not well established.

Aims

1) To compare the effects of different TCT isomers on inflammation, endothelial activation, and endothelial nitric oxide synthase (eNOS). 2) To identify the two most potent TCT isomers in stimulated human endothelial cells. 3) To investigate the effects of TCT isomers on NFκB activation, and protein and gene expression levels in stimulated human endothelial cells.

Methods

Human umbilical vein endothelial cells were incubated with various concentrations of TCT isomers or α-TOC (0.3–10 µM), together with lipopolysaccharides for 16 h. Supernatant cells were collected and measured for protein and gene expression of cytokines (interleukin-6, or IL-6; tumor necrosis factor-alpha, or TNF-α), adhesion molecules (intercellular cell adhesion molecule-1, or ICAM-1; vascular cell adhesion molecule-1, or VCAM-1; and e-selectin), eNOS, and NFκB.

Results

δ-TCT is the most potent TCT isomer in the inhibition of IL-6, ICAM-1, VCAM-1, and NFκB, and it is the second potent in inhibiting e-selectin and eNOS. γ-TCT isomer is the most potent isomer in inhibiting e-selectin and eNOS, and it is the second most potent in inhibiting is IL-6, VCAM-1, and NFκB. For ICAM-1 protein expression, the most potent is δ-TCT followed by α-TCT. α- and β-TCT inhibit IL-6 at the highest concentration (10 µM) but enhance IL-6 at lower concentrations. γ-TCT markedly increases eNOS expression by 8–11-fold at higher concentrations (5–10 µM) but exhibits neutral effects at lower concentrations.

Conclusion

δ- and γ-TCT are the two most potent TCT isomers in terms of the inhibition of inflammation and endothelial activation whilst enhancing eNOS, possibly mediated via the NFκB pathway. Hence, there is a great potential for TCT isomers as anti-atherosclerotic agents.

The role of phosphodiesterase-5 inhibitors in prostatic inflammation: a review

Clinical and basic experimental evidence indicates that chronic inflammation is the greatest factor in benign prostatic hyperplasia (BPH) progression, which is the most common cause of Lower Urinary Tract Symptoms (LUTS). The use of anti-inflammatory agents such as steroids, cyclooxygenase-2 (COX-2) and phytotherapics have been investigated as forms of treatment for various prostate diseases. Recent evidence has demonstrated that PDE5 inhibitors (PDE5Is) improve symptoms of BPH/LUTS, possibly as a result of the relaxing of the smooth muscle fibers of the bladder and prostate by NO/cGMPc signaling, or by improving RhoA/Rho-kinase (ROCK), and reduction of the hyperactivity of the autonomic nervous system. However, some results have suggested that besides vasodilatation and their anti-proliferative effect, PDE5Is exert a direct anti-inflammatory effect, by raising cGMP. Given that inflammation is major factor in benign prostatic hyperplasia (BPH) progression, PDE5Is could act also restore prostatic function as they act as potent anti-inflammatory drugs. This review aims to provide a comprehensive summary of the use of phosphodiesterase-5 inhibitors to treat prostatic inflammation.

Carotid Endothelial VCAM-1 Is an Early Marker of Carotid Atherosclerosis and Predicts Coronary Artery Disease in Swine

Objective

The aim was to determine if endothelial VCAM-1 (eVCAM-1) expression in the common carotid artery (CCA) would correlate with predictive markers of atherosclerotic disease, would precede reduction of markers of endothelial cell function and would predict coronary artery disease (CAD).

Methods and results

Carotid arterial segments (bifurcation, proximal and distal CCA) were harvested from 14 and 24 month-old male castrated familial hypercholesterolemic (FH) swine, a model of spontaneous atherosclerosis. Quantification of local expression of eVCAM-1, intimal macrophage accumulation, oxidative stress, intima-media (I/M) ratio, intima-media thickness (IMT), endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS (p-eNOS) in selected regions of the carotids revealed a relationship between local inflammation and atheroscle-rotic plaque progression. Importantly, inflammation was not uniform throughout the CCA. Endo-thelial VCAM-1 expression was the greatest at the bifurcation and increased with age. Finally, eV-CAM-1 best estimated the severity of CAD compared to blood levels of glucose, hypercholestero-lemia, carotid IMT, and p-eNOS.

Conclusion

Our data suggested that eVCAM-1 was closely associated with atherosclerotic plaque progression and preceded impairment of EDD. Thus, this study supported the use of carotid VCAM-1 targeting agents to estimate the severity of CAD.

Phosphodiesterase-5 Inhibitors: Action on the Signaling Pathways of Neuroinflammation, Neurodegeneration, and Cognition

Phosphodiesterase type 5 inhibitors (PDE5-Is) have recently emerged as a potential therapeutic strategy for neuroinflammatory, neurodegenerative, and memory loss diseases. Mechanistically, PDE5-Is produce an anti-inflammatory and neuroprotection effect by increasing expression of nitric oxide synthases and accumulation of cGMP and activating protein kinase G (PKG), the signaling pathway of which is thought to play an important role in the development of several neurodiseases, such as Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). The aim of this paper was to review present knowledge of the signaling pathways that underlie the use of PDE5-Is in neuroinflammation, neurogenesis, learning, and memory.

Bidirectional cross-regulation between the endothelial nitric oxide synthase and β-catenin signalling pathways

AIMS

β-catenin has been shown to be regulated by inducible nitric oxide synthase (NOS) in endothelial cells. We investigated here whether β-catenin interacts with and regulates endothelial NOS (eNOS) and whether eNOS activation promotes β-catenin signalling.

METHODS AND RESULTS

We identified β-catenin as a novel eNOS binding protein in human umbilical vein endothelial cells (HUVECs) by mass spectroscopy and western blot analyses of β-catenin and eNOS immunoprecipitates. This was confirmed by in situ proximity ligation assay. eNOS activity, assessed by cGMP production and eNOS phosphorylation (Ser1177), was enhanced in β-catenin(-/-) mouse pulmonary endothelial cells (MPECs) relative to wild-type MPECs. eNOS activation (using adenosine, salbutamol, thrombin, or histamine), or application of an NO donor (spermine NONOate) or cGMP-analogue (8-bromo-cGMP) caused nuclear translocation of β-catenin in HUVEC as shown by western blotting of nuclear extracts. Exposure to spermine NONOate, 8-bromo-cGMP, or sildenafil (a phosphodiesterase type 5 inhibitor) also increased the expression of β-catenin-dependent transcripts, IL-8, and cyclin D1. Stimulation of wild-type MPECs with basic fibroblast growth factor (bFGF), vascular endothelial growth factor (VEGF), spermine NONOate, 8-bromo-cGMP, or sildenafil increased tube length relative to controls in an angiogenesis assay. These responses were abrogated in β-catenin(-/-) MPECs, with the exception of that to bFGF which is NO-independent. In C57BL/6 mice, subcutaneous VEGF-supplemented Matrigel plugs containing β-catenin(-/-) MPECs exhibited reduced angiogenesis compared with plugs containing wild-type MPECs. Angiogenesis was not altered in bFGF-supplemented Matrigel.

CONCLUSION

These data reveal bidirectional cross-talk and regulation between the NO-cGMP and β-catenin signalling pathways.

Mechanisms and targets of the modulatory action of S-nitrosoglutathione (GSNO) on inflammatory cytokines expression

A number of experimental studies has documented that S-nitrosoglutathione (GSNO), the main endogenous low-molecular-weight S-nitrosothiol, can exert modulatory effects on inflammatory processes, thus supporting its potential employment in medicine for the treatment of important disease conditions. At molecular level, GSNO effects have been shown to modulate the activity of a series of transcription factors (notably NF-κB, AP-1, CREB and others) as well as other components of signal transduction chains (e.g. IKK-β, caspase 1, calpain and others), resulting in the modulation of several cytokines and chemokines expression (TNFα, IL-1β, IFN-γ, IL-4, IL-8, RANTES, MCP-1 and others). Results reported to date are however not univocal, and a single main mechanism of action for the observed anti-inflammatory effects of GSNO has not been identified. Conflicting observations can be explained by differences among the various cell types studies as to the relative abundance of enzymes in charge of GSNO metabolism (GSNO reductase, γ-glutamyltransferase, protein disulfide isomerase and others), as well as by variables associated with the individual experimental models employed. Altogether, anti-inflammatory properties of GSNO seem however to prevail, and exploration of the therapeutic potential of GSNO and analogues appears therefore warranted.

Potent stimulation of blood flow in fingers of volunteers after local short-term treatment with low-frequency magnetic fields from a novel device

A novel hand-held low-frequency magnetic stimulator (MagCell-SR) was tested for its ability to stimulate microcirculation in fingers of healthy volunteers. Blood flow during and after 5 minutes exposure was quantified using Laser Doppler Perfusion Imaging Technique. The device was positioned between the wrist and the dorsal part of the backhand. Because the increase in blood flow could be caused by a release of nitric oxide (NO) from the vascular endothelial cells we tested NO production with a fluorescence marker and quantified the measurements in cell cultures of human umbilical endothelial cells (HUVEC). Exposure increased blood flow significantly, persisted several minutes, and then disappeared gradually. In order to assess the effect of a static magnetic field, the measurements were also carried out with the device shutoff. Here, only a small increase in blood flow was noted. The application of the rotating MagCell-SR to the HUVEC cultures leads to a rapid onset and a significant increase of NO release after 15 minutes. Thus, frequencies between 4 and 12 Hz supplied by the device improve microcirculation significantly. Therefore, this device can be used in all clinical situations where an improvement of the microcirculation is useful like in chronic wound healing deficits.

Combined treatment of hydroxytyrosol with carbon monoxide-releasing molecule-2 prevents TNF α-induced vascular endothelial cell dysfunction through NO production with subsequent NFκB inactivation

This study investigated the atheroprotective properties of olive oil polyphenol, hydroxytyrosol (HT), in combination with carbon monoxide-releasing molecule-2 (CORM-2) that acts as a carbon monoxide donor using vascular endothelial cells (VECs). Our results showed that CORM-2 could strengthen the cytoprotective and anti-apoptotic effects of HT against TNFα-induced cellular damage by enhancing cell survival and the suppression of caspase-3 activation. While HT alone attenuated NFκBp65 phosphorylation and IκBα degradation triggered by TNFα in a dose-dependent manner, combined treatment of HT with CORM-2 but not iCORM-2 nearly completely blocked these TNFα effects. Furthermore, combined action of both compounds results in the inhibition of NFκB nuclear translocation. Results also indicate that both compounds time-dependently increased eNOS phosphorylation levels and the combination of HT with CORM-2 was more effective in enhancing eNOS activation and NO production in VECs. The NOS inhibitor, L-NMMA, significantly suppressed the combined effects of HT and CORM-2 on TNFα-triggered NFκBp65 and IκBα phosphorylation as well as decreased cell viability. Together, these data suggest that carbon monoxide-dependent regulation of NO production by the combination of HT with CORM-2 may provide a therapeutic benefit in the treatment of endothelial dysfunction and atherosclerosis.

Interference with akt signaling protects against myocardial infarction and death by limiting the consequences of oxidative stress

The intricacy of multiple feedback loops in the pathways downstream of Akt allows this kinase to control multiple cellular processes in the cardiovascular system and precludes inferring consequences of its activation in specific pathological conditions. Akt1, the major Akt isoform in the heart and vasculature, has a protective role in the endothelium during atherosclerosis. However, Akt1 activation may also have detrimental consequences in the cardiovascular system. Mice lacking both the high-density lipoprotein receptor SR-BI (scavenger receptor class B type I) and ApoE (apolipoprotein E), which promotes clearance of remnant lipoproteins, are a model of severe dyslipidemia and spontaneous myocardial infarction. We found that Akt1 was activated in these mice, and this activation correlated with cardiac dysfunction, hypertrophy, and fibrosis; increased infarct area; cholesterol accumulation in macrophages and atherosclerosis; and reduced life span. Akt1 activation was associated with inflammation, oxidative stress, accumulation of oxidized lipids, and increased abundance of CD36, a major sensor of oxidative stress, and these events created a positive feedback loop that exacerbated the consequences of oxidative stress. Genetic deletion of Akt1 in this mouse model resulted in decreased mortality, alleviation of multiple complications of heart disease, and reduced occurrence of spontaneous myocardial infarction. Thus, interference with Akt1 signaling in vivo could be protective and improve survival under dyslipidemic conditions by reducing oxidative stress and responses to oxidized lipids.

Role of caveolin-1 and caveolae signaling in endotoxemia and sepsis

Caveolae, plasma membrane invaginations of 60-80nm in diameter, are a subset of lipid rafts enriched in cholesterol and sphingolipids. Caveolae are expressed in various tissues and cell types, such as endothelial cells, macrophages, neutrophils and adipocytes. The functions of caveolae are diverse and include endocytosis, transcytosis, potocytosis, calcium signaling, and regulation of various signaling events. Although growing evidence has increased our understanding of caveolae function, the role of caveolae in sepsis is still a controversial issue. In this review, we present a number of studies addressing caveolae and sepsis and describe the signaling pathways involved, including the LPS-eNOS-TLR4-NFκB, MKK3/p38 MAPK, cPLA2/p38 MAPK, STAT3/NFκB and IL-1β-IL-1R1 pathways. Different studies using endotoxemia and bacteremia animal models have provided distinct conclusions about the function of caveolae, and we discuss these inconsistencies. Taken together, the current data suggest that the function of caveolae in sepsis, which involves a number of signaling pathways, is complex and warrants further studies.

Bile acid receptor TGR5 agonism induces NO production and reduces monocyte adhesion in vascular endothelial cells

OBJECTIVE

TGR5 is a G-protein-coupled receptor for bile acids. So far, little is known about the function of TGR5 in vascular endothelial cells.

APPROACH AND RESULTS

In bovine aortic endothelial cells, treatment with a bile acid having a high affinity to TGR5, taurolithocholic acid (TLCA), significantly increased NO production. This effect was abolished by small interfering RNA-mediated depletion of TGR5. TLCA-induced NO production was also observed in human umbilical vein endothelial cells measured via intracellular cGMP accumulation. TLCA increased endothelial NO synthase(ser1177) phosphorylation in human umbilical vein endothelial cells. This response was accompanied by increased Akt(ser473) phosphorylation and intracellular Ca(2+). Inhibition of these signals significantly decreased TLCA-induced NO production. We next examined whether TGR5-mediated NO production affects inflammatory responses of endothelial cells. In human umbilical vein endothelial cells, TLCA significantly reduced tumor necrosis factor-α-induced adhesion of monocytes, vascular cell adhesion molecule-1 expression, and activation of nuclear factor-κB. TLCA also inhibited lipopolysaccharide-induced monocyte adhesion to mesenteric venules in vivo. These inhibitory effects of TLCA were abrogated by NO synthase inhibition.

CONCLUSIONS

TGR5 agonism induces NO production via Akt activation and intracellular Ca(2+) increase in vascular endothelial cells, and this function inhibits monocyte adhesion in response to inflammatory stimuli.

Pharmacologic inhibition of CXCL10 in combination with anti-malarial therapy eliminates mortality associated with murine model of cerebral malaria

Despite appropriate anti-malarial treatment, cerebral malaria (CM)-associated mortalities remain as high as 30%. Thus, adjunctive therapies are urgently needed to prevent or reduce such mortalities. Overproduction of CXCL10 in a subset of CM patients has been shown to be tightly associated with fatal human CM. Mice with deleted CXCL10 gene are partially protected against experimental cerebral malaria (ECM) mortality indicating the importance of CXCL10 in the pathogenesis of CM. However, the direct effect of increased CXCL10 production on brain cells is unknown. We assessed apoptotic effects of CXCL10 on human brain microvascular endothelial cells (HBVECs) and neuroglia cells in vitro. We tested the hypothesis that reducing overexpression of CXCL10 with a synthetic drug during CM pathogenesis will increase survival and reduce mortality. We utilized atorvastatin, a widely used synthetic blood cholesterol-lowering drug that specifically targets and reduces plasma CXCL10 levels in humans, to determine the effects of atorvastatin and artemether combination therapy on murine ECM outcome. We assessed effects of atorvastatin treatment on immune determinants of severity, survival, and parasitemia in ECM mice receiving a combination therapy from onset of ECM (day 6 through 9 post-infection) and compared results with controls. The results indicate that CXCL10 induces apoptosis in HBVECs and neuroglia cells in a dose-dependent manner suggesting that increased levels of CXCL10 in CM patients may play a role in vasculopathy, neuropathogenesis, and brain injury during CM pathogenesis. Treatment of ECM in mice with atorvastatin significantly reduced systemic and brain inflammation by reducing the levels of the anti-angiogenic and apoptotic factor (CXCL10) and increasing angiogenic factor (VEGF) production. Treatment with a combination of atorvastatin and artemether improved survival (100%) when compared with artemether monotherapy (70%), p<0.05. Thus, adjunctively reducing CXCL10 levels and inflammation by atorvastatin treatment during anti-malarial therapy may represent a novel approach to treating CM patients.

Propofol protects against high glucose-induced endothelial adhesion molecules expression in human umbilical vein endothelial cells

BACKGROUND

Hyperglycemia could induce oxidative stress, activate transcription factor nuclear factor kappa B (NF-κB), up-regulate expression of endothelial adhesion molecules, and lead to endothelial injury. Studies have indicated that propofol could attenuate oxidative stress and suppress NF-κB activation in some situations. In the present study, we examined whether and how propofol improved high glucose-induced up-regulation of endothelial adhesion molecules in human umbilical vein endothelial cells (HUVECs).

METHODS

Protein expression of endothelial adhesion molecules, NF-κB, inhibitory subunit of NF-κBα (IκBα), protein kinase Cβ2 (PKCβ2), and phosphorylation of PKCβ2 (Ser(660)) were measured by Western blot. NF-κB activity was measured by electrophoretic mobility shift assay. PKC activity was measured with SignaTECT PKC assay system. Superoxide anion (O(2)(.-)) accumulation was measured with the reduction of ferricytochrome c assay. Human peripheral mononuclear cells were prepared with Histopaque-1077 solution.

RESULTS

High glucose induced the expression of endothelial selectin (E-selectin), intercellular adhesion molecule 1 (ICAM-1), vascular cell adhesion molecule 1 (VCAM-1), and increased mononuclear-endothelial adhesion. High glucose induced O(2)(.-) accumulation, PKCβ2 phosphorylation and PKC activation. Further, high glucose decreased IκBα expression in cytoplasm, increased the translocation of NF-κB from cytoplasm to nuclear, and induced NF-κB activation. Importantly, we found these high glucose-mediated effects were attenuated by propofol pretreatment. Moreover, CGP53353, a selective PKCβ2 inhibitor, decreased high glucose-induced NF-κB activation, adhesion molecules expression, and mononuclear-endothelial adhesion.

CONCLUSION

Propofol, via decreasing O(2)(.-) accumulation, down-regulating PKCβ2 Ser(660) phosphorylation and PKC as well as NF-κB activity, attenuated high glucose-induced endothelial adhesion molecules expression and mononuclear-endothelial adhesion.

Nitric oxide and cell death in liver cancer cells

Nitric oxide (NO) is a lipophillic, highly diffusible, and short-lived physiological messenger which regulates a variety of physiopathological responses. NO may exert its cellular action through cGMP-dependent and cGMP-independent pathways which includes different postranslational modifications. The effect of NO in cancer depends on the activity and localization of NOS isoforms, concentration and duration of NO exposure, cellular sensitivity, and hypoxia/re-oxygenation process. NO regulates critical factors such as the hypoxia inducible factor-1 (HIF-1) and p53 generally leading to growth arrest, apoptosis or adaptation. NO sensitizes hepatoma cells to chemotherapeutic compounds probably through increased p53 and cell death receptor expressions.

Effect of new thiazolidine derivatives LPSF/GQ-02 and LPSF/GQ-16 on atherosclerotic lesions in LDL receptor-deficient mice (LDLR(-/-))

BACKGROUND

Atherosclerotic cardiovascular disease is a chronic inflammatory condition. Thiazolidinediones (TZDs) are used to enhance sensitivity to insulin and have demonstrated a protective effect over a variety of cardiovascular markers and risk factors. Controversially, the TZDs are associated with the development of heart failure. Thus, lines of research have invested in the search for new molecules in order to obtain more selective and less harmful treatment alternatives for the pathogenesis of atherosclerosis and its risk factors.

METHODS

Animals were fed a diet rich in fat for 10 weeks. In the last 2 weeks, animals received either pioglitazone, LPSF/GQ-02, or LPSF/GQ-16 daily through gavage. At the end of the treatment, blood was collected for biochemical analysis and the aortas were dissected for subsequent analyses.

RESULTS

No changes in the blood lipid profile were found following the use of the drugs in comparison to the control. However, the new thiazolidine derivatives were more efficient in improving insulin resistance in comparison to pioglitazone and the control group. Morphometric analyses revealed that neither pioglitazone nor LPSF/GQ16 led to satisfactory effects over atherosclerosis. However, LPSF/GQ-02 led to a reduction in area of the atherosclerotic lesions. Ultrastructural analyses revealed extensive degeneration of the endothelium and an increase in apoptotic cells in the subendothelial space following the use of pioglitazone and LPSF/GQ-16. However, LPSF/GQ-02 caused minimal cell alterations in the aortic endothelium. Regarding markers, endothelial nitric oxide synthase (eNOS) and matrix metalloproteinase 9 (MMP-9), LPSF/GQ-16, and pioglitazone exerted similar effects, increasing the expression of MMP-9, and had no effect on the expression of eNOS compared with the control group. On the other hand, LPSF/GQ-02 was effective in reducing the expression of MMP-9 and increased eNOS significantly.

CONCLUSIONS

The results suggest that the new thiazolidine derivative LPSF/GQ-02 is a promising candidate for the treatment of atherosclerosis.

Alpha-tocopherol and BAY 11-7082 reduce vascular cell adhesion molecule in human aortic endothelial cells

BACKGROUND

In endothelial dysfunction, vascular cell adhesion molecule-1 (VCAM-1), E-selectin and intercellular adhesion molecule-1 (ICAM-1) expression (collectively termed cell adhesion molecules; CAMs) increase at sites of atherosclerosis and are stimulated by proinflammatory cytokines such as tumor necrosis factor-α (TNF-α).

METHODS

We evaluated the effect of alpha-tocopherol (AT; 10-150 µM) and BAY 11-7082 (BAY; 0.1 or 1 µM) on CAMs mRNA expression as well as their protein in soluble release form (sCAMs) in human aortic endothelial cells (HAECs) activated by TNF-α (1 or 10 ng/ml). Also, we determined the extent of lymphocyte adhesion to activated HAECs.

RESULTS

BAY reduced VCAM-1, E-selectin and ICAM-1 mRNA expression by 30, 30 and 10%, respectively. Furthermore, protein reduction of sVCAM-1 by 70%, sE-selectin by 51% and sICAM-1 by 25% compared to HAECs stimulated by TNF-α was observed (p < 0.05). AT (50, 75 and 150 µM) decreased VCAM-1 mRNA expression by 30% and sVCAM-1 protein by 33% compared to HAECs stimulated by TNF-α (p < 0.05). TNF-α-activated HAEC adhesion to human Jurkat T lymphocytes was higher compared to nonactivated HAECs (p < 0.05). BAY (2 and 5 µM) reduced this lymphocyte adhesion (p < 0.05).

CONCLUSION

BAY reduces all the CAMs studied as well as cell adhesion, while AT selectively inhibits VCAM-1; both induce endothelial dysfunction improvement.

β-Carotene and lycopene affect endothelial response to TNF-α reducing nitro-oxidative stress and interaction with monocytes

SCOPE

Cardiovascular disease (CVD) is associated with vascular oxidative imbalance and inflammation. Increased reactive oxygen species (ROS) generation is associated with a functional inactivation of nitric oxide (NO) due to the reaction with O₂⁻, leading to peroxynitrite (ONOO⁻) formation and subsequent reduction in the beneficial effect of vascular NO bioavailability. Carotenoids'-rich diets have been associated with decreased risk of CVD, but the underlying mechanism is still unknown.

METHODS AND RESULTS

In human umbilical vein endothelial cells (HUVECs), both β-carotene (BC) or lycopene (Lyc) significantly affected tumor necrosis factor-α (TNF-α)-induced inflammation, being associated with a significant decrease in the generation of ROS (spectrofluorometry) and nitrotyrosine (an index of ONOO⁻ formation, cytofluorimetry), an increased NO/cGMP (cyclic guanosine monophosphate) levels (EIA), and a down-regulation of NF-κB-dependent adhesion molecule expression (Western blot and EMSA) and monocyte-HUVEC interaction (adhesion assay). Our results indicate that BC or Lyc treatment reduce the inflammatory response in TNF-α-treated HUVECs. This is due to the redox balance protection and to the maintenance of NO bioavailability.

CONCLUSION

Our observations provide background for a novel mechanism for carotenoids' anti-inflammatory activity in the vasculature and may contribute to a better understanding of the protective effects of carotenoid-rich diets against CVD risk.