Adenosine-Dependent Induction of Glutathione Peroxidase 1 in Human Primary Endothelial Cells and Protection Against Oxidative Stress

ROS regulation in gliomas: implications for treatment strategies

Gliomas are one of the most common primary malignant tumours of the central nervous system (CNS), of which glioblastomas (GBMs) are the most common and destructive type. The glioma tumour microenvironment (TME) has unique characteristics, such as hypoxia, the blood-brain barrier (BBB), reactive oxygen species (ROS) and tumour neovascularization. Therefore, the traditional treatment effect is limited. As cellular oxidative metabolites, ROS not only promote the occurrence and development of gliomas but also affect immune cells in the immune microenvironment. In contrast, either too high or too low ROS levels are detrimental to the survival of glioma cells, which indicates the threshold of ROS. Therefore, an in-depth understanding of the mechanisms of ROS production and scavenging, the threshold of ROS, and the role of ROS in the glioma TME can provide new methods and strategies for glioma treatment. Current methods to increase ROS include photodynamic therapy (PDT), sonodynamic therapy (SDT), and chemodynamic therapy (CDT), etc., and methods to eliminate ROS include the ingestion of antioxidants. Increasing/scavenging ROS is potentially applicable treatment, and further studies will help to provide more effective strategies for glioma treatment.

Eldecalcitol inhibits the progression of oral cancer by suppressing the expression of GPx-1

OBJECTIVES

This study aimed to investigate the role of eldecalcitol in the progression of oral squamous cell carcinoma and to explore the related mechanism.

MATERIALS AND METHODS

The effects of eldecalcitol on the proliferation, cell cycle, apoptosis, and migration of oral cancer cells (SCC-15 and CAL-27) were evaluated with cell counting kit-8, flow cytometry, quantitative real-time polymerase chain reaction, western blotting, and scratch assay. Mouse xenograft tumor model was established to further confirm the role of eldecalcitol in the progression of oral cancer. Immunohistochemistry, quantitative real-time polymerase chain reaction, and western blotting were used to detect glutathione peroxidase-1 expression in oral cancer tissue and cells treated with eldecalcitol.

RESULTS

Eldecalcitol was found to inhibit the proliferation and migration of SCC-15 and CAL-27 cells significantly, block the cell cycle in the G0/G1 phase, and enhance the apoptosis. In addition, glutathione peroxidase-1 was downregulated by eldecalcitol and acted as an important medium of eldecalcitol in inhibiting the proliferation and migration of SCC-15 and CAL-27 cells, as well as promoting their apoptosis.

CONCLUSIONS

Eldecalcitol may inhibit the progression of oral cancer by suppressing the expression of glutathione peroxidase-1, which may provide new insight into the application of eldecalcitol as a potential anti-cancer drug.

Adenosine protects D-galactose induced alterations in rat model of aging via attenuating neurochemical profile and redox status

Aging is the process that every organism faces. The aging model of brain has been developed by the use of d-galactose (d-Gal). Adenosine (Ad) being a neuroprotective agent that has been utilized in treatment of various neurological disorders. The aim of current study is to evaluate the outcome of Ad on d-Gal induced neurotoxicity which caused behavioral deficits, memory impairment and oxidative stress. Rats were treated with d-Gal at a dose of 300 mg/ml/kg and Ad 1 mg/ml/kg; intraperitoneally for 28 days. Behavioral assessment was performed after the treatment period. Animals were sacrificed after behavioral tests and their brains were collected, hippocampus were removed for biochemical and neurochemical analysis. The results showed that administration of Ad ameliorates the negative effects of d-Gal induced aging in various behavioral tests and increased the time spent in the open arm and light box in elevated plus maze (EPM) and light dark activity (LDA) tests respectively indicate anxiolytic effect; increased the mobility time in tail suspension test (TST) shows antidepressant effect; decreased escape latencies in Morris water maze (MWM) acquisition trials, increase entries and time spent in the target quadrant suggests improvement in learning ability of animals. Administration of Ad also decreased malondialdehyde (MDA) levels, increased antioxidant enzymes activity; decreased acetylcholinesterase (AChE) activity, increased 5-hydroxytryptamine (5-HT, serotonin) metabolism and normalized histopathological alteration in the hippocampus. It is concluded that anxiety, depression and memory impairment induced by d-Gal were protected by Ad through its antioxidant and neuro-modulatory effects.

Mechanism of Cordyceps sinensis and its Extracts in the Treatment of Diabetic Kidney Disease: A Review

Diabetic kidney disease (DKD) is the major reason of chronic kidney disease (CKD)-caused end-stage renal failure (ESRF), and leads to high mortality worldwide. At present, the treatment of DKD is mainly focused on controlling the hyperglycemia, proteinuria, and hypertension, but is insufficient on the effective delay of DKD progression. Cordyceps sinensis is a kind of wild-used precious Chinese herb. Its extracts have effects of nephroprotection, hepatoprotection, neuroprotection, and protection against ischemia/reperfusion-induced injury, as well as anti-inflammatory and anti-oxidant activities. According to the theory of traditional Chinese medicine, Cordyceps sinensis can tonify the lung and the kidney. Several Chinese patent medicines produced from Cordyceps sinensis are often used to treat DKD and achieved considerable efficacy. This review summarized the clinical usage of Cordyceps sinensis, as well as its mainly biological activities including anti-hyperglycemic, anti-inflammatory, immunomodulatory, anti-oxidant, anti-fibrotic activities and regulation of apoptosis.

Human glutathione peroxidase codon 198 variant increases nasopharyngeal carcinoma risk and progression

PURPOSE

Glutathione peroxidase 1 (GPx-1) is a selenium-dependent detoxifying enzyme involved in the protection of cells against oxidative damage. Some genetic association studies reported significant associations between GPx-1 Pro198Leu variant and carcinogenesis across different populations; however, the impact of this variant on nasopharyngeal carcinoma (NPC) has not been explored. Therefore, the present study was planned to evaluate the potential involvement of the GPx-1 Pro198Leu variant and plasma GPx activity in the risk of developing NPC in a Tunisian population.

METHODS

The GPx-1 Pro198Leu genotype was determined in 327 NPC patients and 150 healthy controls by the RFLP-PCR analysis. The correlation between the GPx-1 variant and the clinicopathological parameters was examined. GPx activity was assessed in the plasma of 119 NPC patients and 58 healthy control subjects and according to GPx-1 genotypes and clinicopathological characteristics of NPC patients.

RESULTS

A significant association was found between GPx-1 Pro198Leu variant and NPC risk in a Tunisian population. The allelic frequencies of Pro and Leu alleles were 32% versus 68% and 41% versus 59% in NPC cases and controls, respectively. Thus, the minor 198 Leu allele increased significantly in NPC patients and appeared as a potential risk factor for NPC occurrence (OR = 1.48, CI 95% = 1.14-1.91, p = 0.002). The plasma GPx activity was significantly higher in NPC patients than in controls (p = 0.03). According to the clinicopathological characteristics of NPC patients, GPx activity decreased significantly in patients with lymph node metastasis (p = 0.004).

CONCLUSION

This is the first study showing a strong association between GPx-1 Pro198Leu genetic variant and NPC risk. GPx-1 Pro198Leu variant increased the development of regional lymph node metastasis. Plasma GPx activity was higher in NPC patients. Thus, GPx-1 gene could be considered as a determinant factor influencing NPC risk and progression.

Suppression of apoptosis in vascular endothelial cell, the promising way for natural medicines to treat atherosclerosis

Atherosclerosis, a chronic multifactorial disease, is closely related to the development of cardiovascular diseases and is one of the predominant causes of death worldwide. Normal vascular endothelial cells play an important role in maintaining vascular homeostasis and inhibiting atherosclerosis by regulating vascular tension, preventing thrombosis and regulating inflammation. Currently, accumulating evidence has revealed that endothelial cell apoptosis is the first step of atherosclerosis. Excess apoptosis of endothelial cells induced by risk factors for atherosclerosis is a preliminary event in atherosclerosis development and might be a target for preventing and treating atherosclerosis. Interestingly, accumulating evidence shows that natural medicines have great potential to treat atherosclerosis by inhibiting endothelial cell apoptosis. Therefore, this paper reviewed current studies on the inhibitory effect of natural medicines on endothelial cell apoptosis and summarized the risk factors that may induce endothelial cell apoptosis, including oxidized low-density lipoprotein (ox-LDL), reactive oxygen species (ROS), angiotensin II (Ang II), tumor necrosis factor-α (TNF-α), homocysteine (Hcy) and lipopolysaccharide (LPS). We expect this review to highlight the importance of natural medicines, including extracts and monomers, in the treatment of atherosclerosis by inhibiting endothelial cell apoptosis and provide a foundation for the development of potential antiatherosclerotic drugs from natural medicines.

Protein network analyses of pulmonary endothelial cells in chronic thromboembolic pulmonary hypertension

Chronic thromboembolic pulmonary hypertension (CTEPH) is a vascular disease characterized by the presence of organized thromboembolic material in pulmonary arteries leading to increased vascular resistance, heart failure and death. Dysfunction of endothelial cells is involved in CTEPH. The present study describes for the first time the molecular processes underlying endothelial dysfunction in the development of the CTEPH. The advanced analytical approach and the protein network analyses of patient derived CTEPH endothelial cells allowed the quantitation of 3258 proteins. The 673 differentially regulated proteins were associated with functional and disease protein network modules. The protein network analyses resulted in the characterization of dysregulated pathways associated with endothelial dysfunction, such as mitochondrial dysfunction, oxidative phosphorylation, sirtuin signaling, inflammatory response, oxidative stress and fatty acid metabolism related pathways. In addition, the quantification of advanced oxidation protein products, total protein carbonyl content, and intracellular reactive oxygen species resulted increased attesting the dysregulation of oxidative stress response. In conclusion this is the first quantitative study to highlight the involvement of endothelial dysfunction in CTEPH using patient samples and by network medicine approach.

Regulation of Mitochondrial Dynamics in Parkinson's Disease-Is 2-Methoxyestradiol a Missing Piece?

Mitochondria, as "power house of the cell", are crucial players in cell pathophysiology. Beyond adenosine triphosphate (ATP) production, they take part in a generation of reactive oxygen species (ROS), regulation of cell signaling and cell death. Dysregulation of mitochondrial dynamics may lead to cancers and neurodegeneration; however, the fusion/fission cycle allows mitochondria to adapt to metabolic needs of the cell. There are multiple data suggesting that disturbed mitochondrial homeostasis can lead to Parkinson's disease (PD) development. 2-methoxyestradiol (2-ME), metabolite of 17β-estradiol (E2) and potential anticancer agent, was demonstrated to inhibit cell growth of hippocampal HT22 cells by means of nitric oxide synthase (NOS) production and oxidative stress at both pharmacologically and also physiologically relevant concentrations. Moreover, 2-ME was suggested to inhibit mitochondrial biogenesis and to be a dynamic regulator. This review is a comprehensive discussion, from both scientific and clinical point of view, about the influence of 2-ME on mitochondria and its plausible role as a modulator of neuron survival.

Acetate causes renoprotection like androgen and mineralocorticoid receptors blockade in testosterone-exposed pregnant rats

The kidney plays a critical role in human health and deviation from its normal function can lead to severe morbidity and mortality. Exposure to excess testosterone in women has been linked to several disorders, including kidney disorder and acting undoubtedly through androgen receptor (AR), whereas the involvement of mineralocorticoid receptor (MR) is unclear. Likewise, the renal effect of sodium acetate (SAc) during late gestational exposure to testosterone is not well known. We hypothesized that SAc or MR blockade would protect the kidney of testosterone-exposed pregnant rats against glutathione and adenosine depletion. Twenty-five pregnant Wistar rats were treated (sc) with olive oil, testosterone propionate (0.5 mg/kg) singly or in combination with SAc (200 mg/kg; p.o.), androgen receptor (AR) blocker, flutamide (Flu; 7.5 mg/kg; p.o.) or (MR) blocker, eplerenone (Eple; 0.5 mg/kg) between gestational days 14 and 19. Glutathione, adenosine and nitric oxide were decreased while uric acid (UA), xanthine oxidase (XO), malondialdehyde (MDA), lactate dehydrogenase activity and free fatty acids were increased in the kidneys of gestational rats exposed to testosterone. Also, plasma urea and creatinine were elevated. SAc and Eple reversed tested testosterone-induced effects in gestational rats. The exposure to testosterone impairs renal antioxidant defense via AR and MR during late gestation in pregnant rats. The study also provides evidence that sodium acetate protects the kidneys of gestational testosterone-exposed rats against defective antioxidant defense in like manner as MR or AR antagonist.

Suppression of uric acid and lactate production by sodium acetate ameliorates hepatic triglyceride accumulation in fructose-insulin resistant pregnant rats

High fructose intake has been associated with perturbed lipid, uric acid and lactate homeostasis. However, consumption of fructose-sweetened beverages is not usually regulated during pregnancy. The effect of short-chain fatty acid (acetate) on the metabolic effects of high fructose intake during pregnancy is not known. We hypothesized that acetate prevents gestational fructose-induced hepatic triglyceride (TG) accumulation by suppressing uric acid and lactate production. Pregnant Wistar rats were randomly separated into three groups (n = 6/group) receiving drinking water (CON), 10 % (w/v) fructose drink (FRU) and 10 % (w/v) fructose with 200 mg/kg (w/w; p.o.) sodium acetate (FRU + ACE) daily for nineteen days. Fructose intake resulted in increased body weight gain, liver weight, fluid intake, visceral fat, insulin resistance, fasting blood glucose, insulin, plasma and hepatic TG, total cholesterol, free fatty acid, lipid peroxidation, adenosine deaminase, xanthine oxidase, uric acid, lactate, lactate dehydrogenase, and liver injury marker enzymes. However, gestational high fructose intake led to depressed plasma and hepatic glucose-6-phosphate dehydrogenase (G6PD)-dependent antioxidant barrier, adenosine and food intake. All these effects except water intake and food intake were abated by sodium acetate. These results demonstrate that maternal fructose-enriched drink would cause hepatic TG accumulation that is associated with perturbed glucose, uric acid, lactate homeostasis, and G6PD-dependent antioxidant barrier. These results also demonstrate that acetate protects the liver against gestational fructose-induced TG accumulation by inhibiting uric acid and lactate production. Thus, acetate may be useful in the treatment of hyperuricemia- and hyperlactatemia-related disorders.

Seleno-l-methionine suppresses copper-enhanced zinc-induced neuronal cell death via induction of glutathione peroxidase

Excessive zinc ion (Zn²⁺) release is induced in pathological situations and causes neuronal cell death. Previously, we have reported that copper ions (Cu²⁺) markedly exacerbated Zn²⁺-induced neuronal cell death by potentiating oxidative stress, the endoplasmic reticulum (ER) stress response, and the activation of the c-Jun amino-terminal kinase (JNK) signaling pathway. In contrast, selenium (Se), an essential trace element, and amino acids containing selenium (such as seleno-l-methionine) have been reported to inhibit stress-induced neuronal cell death and oxidative stress. Thus, we investigated the effect of seleno-l-methionine on Cu²⁺/Zn²⁺-induced neuronal cell death in GT1-7 cells. Seleno-l-methionine treatment clearly restored the Cu²⁺/Zn²⁺-induced decrease in the viable cell number and attenuated the Cu²⁺/Zn²⁺-induced cytotoxicity. Accordingly, the levels of ER stress-related factors (especially, CHOP and GADD34) and of phosphorylated JNK increased upon CuCl₂ and ZnCl₂ co-treatment, whereas pre-treatment with seleno-l-methionine significantly suppressed these upregulations. Analysis of reactive oxygen species (ROS) as upstream factors of these pathways revealed that Cu²⁺/Zn²⁺-induced ROS production was clearly suppressed by seleno-l-methionine treatment. Finally, we found that seleno-l-methionine induced the antioxidative protein, glutathione peroxidase. Taken together, our findings suggest that seleno-l-methionine suppresses Cu²⁺/Zn²⁺-induced neuronal cell death and oxidative stress via induction of glutathione peroxidase. Thus, we think that seleno-l-methionine may help prevent refractory neurological diseases.

The role of diabetes in the onset and development of endothelial dysfunction

The vascular endothelium performs many functions. It is a key regulator of vascular homeostasis, maintains a balance between vasodilation and vasoconstriction, inhibition and stimulation of smooth muscle cell migration and proliferation, fibrinolysis and thrombosis, and is involved to regulation of platelet adhesion and aggregation. Endothelial dysfunction (ED) plays the critical role in pathogenesis of diabetes mellitus (DM) vascular complications. The purpose of this review was to consider the mechanisms leading to the occurrence of ED in DM. The paper discusses current literature data concerning the role of hyperglycemia, oxidative stress, advanced glycation end products in endothelial alteration. A separate section is devoted to the particularities of the functioning of the antioxidant system and their significance in the development of ED in DM. The analysis of the literature allows to conclude that pathological activation of glucose utilization pathways causes damage of endothelial cells, which is accompanied by disorders of all their basic functions. Metabolic disorders in DM cause a pronounced imbalance of free radical processes and antioxidant defense, accompanied by oxidative stress of endotheliocytes, which contributes to the progression of ED and the development of vascular complications. Many aspects of multicomponent regulatory reactions in the pathogenesis of the development of ED in DM have not been sufficiently studied.

Early morphological changes in cardiac mitochondria after subcutaneous administration of trastuzumab in rabbits: possible prevention with oral selenium supplementation

Trastuzumab-mediated cardiotoxicity poses a significant challenge in the treatment of human epidermal growth factor receptor 2-positive breast cancer. To understand the underlying mechanisms, we conducted experiments to determine ultrastructural changes of rabbit cardiac tissue under different experimental conditions, including differing doses of trastuzumab and supplementation with oral sodium selenite, an antioxidant. Histopathology revealed lymphocyte and macrophage infiltration in myocardium of rabbits receiving four doses of trastuzumab. Transmission electron microscopy showed substantial changes with trastuzumab, including edema with separation of myofibril bundles and rupture of sarcomeres. Within mitochondria, edema resulted in disorganization of the cristae. Some mitochondria exhibited eccentric projections of their membranes with disruption of both inner and outer membranes. These changes were seen to a lesser extent in rabbits who received oral sodium selenite prior to trastuzumab. Selenium is integral to functioning of mitochondrial glutathione peroxidases, important antioxidants that also maintain membrane integrity. If mitochondria are disrupted as part of trastuzumab cardiac toxicity, selenium supplementation might be an important therapeutic or preventive consideration. Larger studies to explore this hypothesis are warranted.

Peptides from Cauliflower By-Products, Obtained by an Efficient, Ecosustainable, and Semi-Industrial Method, Exert Protective Effects on Endothelial Function

The large amount of cauliflower industry waste represents an unexplored source of bioactive compounds. In this work, peptide hydrolysates from cauliflower leaves were characterized by combined bioanalytical approaches. Twelve peptide fractions were studied to evaluate unexplored biological activities by effect-based cellular bioassays. A potent inhibition of intracellular xanthine oxidase activity was observed in human vascular endothelial cells treated with one fraction, with an IC50 = 8.3 ± 0.6 μg/ml. A different fraction significantly induced the antioxidant enzyme superoxide dismutase 1 and decreased the tumor necrosis factor α-induced VCAM-1 expression, thus leading to a significant improvement in the viability of human vascular endothelial cells. Shotgun peptidomics and bioinformatics were used to retrieve the most probable bioactive peptide sequences. Our study shows that peptides from cauliflower waste should be recycled for producing valuable products useful for the prevention of endothelial dysfunction linked to atherogenesis progression.

Enhanced hepatic glycogen synthesis and suppressed adenosine deaminase activity by lithium attenuates hepatic triglyceride accumulation in nicotine-exposed rats

Reduced liver glycogen synthesis might signify increased glucose flux towards fat synthesis and triggers hepatic triglyceride accumulation and dysmetabolism. Adenosine deaminase (ADA) reduces adenosine content which increases glycogenolysis. In the present study, we evaluate the effect of modulating glycogen synthesis and ADA by lithium chloride (LiCl) on nicotine-induced dysmetabolism. Twenty four male Wistar rats (n = 6/group) were allotted into four groups namely; vehicle-treated (po), nicotine-treated (1.0 mg/kg; po), LiCl-treated (5.0 mg/kg; po) and nicotine + LiCl-treated groups. The treatments lasted for 8 weeks. Nicotine exposure resulted in reduced body weight gain, liver weight, visceral adiposity, glycogen content and synthase. Along with increased insulin resistance (IR), fasting plasma glucose, lactate, plasma and hepatic ADA, XO, UA, and triglyceride (TG), total cholesterol (TC), free fatty acid, lipid peroxidation and liver injury markers. However, plasma and hepatic glucose-6-phosphate dehydrogenase-dependent antioxidant defenses were not affected by nicotine exposure. Concurrent treatment with LiCl normalizes all alterations with exception of hepatic TC. This result shows that enhancement of hepatic glycogen synthesis and suppression of ADA/XO/uric acid pathway by lithium can salvage the liver from nicotine-induced TG accumulation.

Endoglin inhibition by sodium acetate and flutamide ameliorates cardiac defective G6PD-dependent antioxidant defense in gestational testosterone-exposed rats

Gestational androgen excess has been implicated in the development of cardiac dysfunction with poor mechanistic delineation. The role of sodium acetate on cardiac uric acid (UA) production and glucose-6-phosphate dehydrogenase (G6PD)-dependent antioxidant defense in pregnancy is not known. The study therefore sought to test the hypothesis that rats exposed to elevated testosterone in late pregnancy would have increased cardiac UA production and defective G6PD-dependent antioxidant defense. We also hypothesized that sodium acetate (SAc) or androgen receptor blocker, flutamide (Flu) would ameliorate these effects through endoglin inhibition. Twenty-four pregnant Wistar rats were treated (sc) with olive oil, testosterone propionate (0.5 mg/kg) singly or in combination with SAc (200 mg/kg; po) or Flu (7.5 mg/kg; po) in the late gestation between gestational day 14 and 19. The results showed that in the late gestation, testosterone exposure led to increased plasma and cardiac endoglin. In the heart of rats exposed to gestational testosterone there were elevated lactate dehydrogenase, adenosine deaminase, xanthine oxidase, uric acid (UA), cardiac injury markers and decreased G6PD-dependent antioxidant defense. However, either SAc or Flu comparably ameliorated these testosterone-induced effects. The data from the present study revealed that testosterone exposure in the late gestation causes elevated cardiac Eng that is accompanied by increased UA production and defective G6PD-dependent anti-oxidant defenses. Besides, the findings also suggest that the inhibitory effect of SAc or Flu on endoglin attenuates UA production and enhances the G6PD-dependent anti-oxidant barrier, thereby implying that endoglin may be a potentially novel therapeutic intervention for cardiac dysfunction particularly in pregnancy.

Sodium acetate and androgen receptor blockade improve gestational androgen excess-induced deteriorated glucose homeostasis and antioxidant defenses in rats: roles of adenosine deaminase and xanthine oxidase activities

Nutritional challenges and androgen excess have been implicated in the development of gestational diabetes and poor fetal outcome, but the mechanisms are not well delineated. The effects of short chain fatty acid (SCFA) on glucose dysmetabolism and poor fetal outcome induced by gestational androgen excess is also not known. We tested the hypothesis that blockade of androgen receptor (AR) and suppression of late gestational androgen excess prevents glucose dysmetabolism and poor fetal outcome through suppression of adenosine deaminase (ADA)/xanthine oxidase (XO) pathway. Twenty-four pregnant Wistar rats were treated (sc) with olive oil, testosterone propionate (0.5 mg/kg) singly or in combination with SCFA (sodium acetate; 200 mg/kg; p.o.) or AR blocker (flutamide; 7.5 mg/kg; p.o.) between gestational days 14 and 19. The results showed that late gestational androgen excess led to glucose deregulation, poor fetal outcome, increased plasma and hepatic free fatty acid and lactate dehydrogenase, liver function marker enzymes, malondialdehyde, uric acid, ADA and XO activities. Conversely, gestational androgen excess resulted in reduced body weight gain, visceral adiposity, plasma and hepatic anti-oxidant defenses (glutathione peroxidase, reduced glutathione/glutathione disulphide ratio, glucose-6-phosphate dehydrogenase, adenosine and nitric oxide). However, all these effects were ameliorated by either sodium acetate or flutamide treatment. The study demonstrates that suppression of testosterone by SCFA or AR blockade protects against glucose deregulation and poor fetal outcome by improvement of anti-oxidant defenses and replenishment of hepatic oxidative capacity through suppression of ADA/XO pathway. Hence, utility of SCFA should be encouraged for prevention of glucose dysmetabolism and poor fetal outcome.

Impacts of selenium and vitamin E supplementation on mRNA of heat shock proteins, selenoproteins and antioxidants in broilers exposed to high temperature

The study was carried out to investigate the effect of dietary selenium (Se) and vitamin E (VE) supplementation on mRNA level of heat shock proteins, selenoproteins, and antioxidant enzyme activities in the breast meat of broilers under summer heat stress conditions. A total of 200 male broilers (Ross 308) of 1 day age were randomly separated into 4 groups in a complete randomized design and were given a basal diet (Control, 0.08 mg Se/kg diet) or basal diet supplemented with VE (250 mg/kg VE), sodium selenite (0.2 mg/kg Se), or Se + VE (0.2 mg/kg Se + 250 mg/kg VE) to investigate the expression of key antioxidant and heat shock protein (HSP) genes under high temperature stress. Dietary Se, VE and Se + VE significantly enhanced the activities and mRNA levels of catalase as well as superoxide dismutase (SOD) but decreased the mRNA levels of HSP70 and HSP90. Se alone or combined with VE increased the concentration of selenoprotein P and selenoproteins mRNA level and decreased the expression of HSP60. In addition, Se and Se + VE significantly enhanced the glutathione peroxidase (GPx) activity and the expression of GPx1 and GPx4 in breast muscle tissues. It is noteworthy that all the treatments significantly decreased malondialdehyde (MDA) level in the breast meat. Overall results showed that Se in combination with VE has maximal effects to mitigate heat stress. Based on given results it can be recommended that Se + VE are a suitable dietary supplement for broilers to ameliorate the negative effects of summer heat stress conditions.

Impact of carbonylation on glutathione peroxidase-1 activity in human hyperglycemic endothelial cells

AIMS

High levels of glucose and reactive carbonyl intermediates of its degradation pathway such as methylglyoxal (MG) may contribute to diabetic complications partly via increased generation of reactive oxygen species (ROS). This study focused on glutathione peroxidase-1 (GPx1) expression and the impact of carbonylation as an oxidative protein modification on GPx1 abundance and activity in human umbilical vein endothelial cells (HUVEC) under conditions of mild to moderate oxidative stress.

RESULTS

High extracellular glucose and MG enhanced intracellular ROS formation in HUVECs. Protein carbonylation was only transiently augmented pointing to an effective antioxidant defense in these cells. Nitric oxide synthase expression was decreased under hyperglycemic conditions but increased upon exposure to MG, whereas superoxide dismutase expression was not significantly affected. Increased glutathione peroxidase (GPx) activity seemed to compensate for a decrease in GPx1 protein due to enhanced degradation via the proteasome. Mass spectrometry analysis identified Lys-114 as a possible carbonylation target which provides a vestibule for the substrate H2O2 and thus enhances the enzymatic reaction.

INNOVATION

Oxidative protein carbonylation has so far been associated with functional inactivation of modified target proteins mainly contributing to aging and age-related diseases. Here, we demonstrate that mild oxidative stress and subsequent carbonylation seem to activate protective cellular redox signaling pathways whereas severe oxidative stress overwhelms the cellular antioxidant defense leading to cell damage.

CONCLUSIONS

This study may contribute to a better understanding of redox homeostasis and its role in the development of diabetes and related vascular complications.

Antipurinergic therapy for autism-An in-depth review

Are the symptoms of autism caused by a treatable metabolic syndrome that traces to the abnormal persistence of a normal, alternative functional state of mitochondria? A small clinical trial published in 2017 suggests this is possible. Based on a new unifying theory of pathogenesis for autism called the cell danger response (CDR) hypothesis, this study of 10 boys, ages 5-14years, showed that all 5 boys who received antipurinergic therapy (APT) with a single intravenous dose of suramin experienced improvements in all the core symptoms of autism that lasted for 5-8weeks. Language, social interaction, restricted interests, and repetitive movements all improved. Two children who were non-verbal spoke their first sentences. None of these improvements were observed in the placebo group. Larger and longer studies are needed to confirm this promising discovery. This review introduces the concept of M2 (anti-inflammatory) and M1 (pro-inflammatory) mitochondria that are polarized along a functional continuum according to cell stress. The pathophysiology of the CDR, the complementary functions of M1 and M2 mitochondria, relevant gene-environment interactions, and the metabolic underpinnings of behavior are discussed as foundation stones for understanding the improvements in ASD behaviors produced by antipurinergic therapy in this small clinical trial.

Oxidative Stress in Cardiovascular Diseases: Involvement of Nrf2 Antioxidant Redox Signaling in Macrophage Foam Cells Formation

Oxidative stress is an important risk factor contributing to the pathogenesis of cardiovascular diseases. Oxidative stress that results from excessive reactive oxygen species (ROS) production accounts for impaired endothelial function, a process which promotes atherosclerotic lesion or fatty streaks formation (foam cells). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor involved in cellular redox homeostasis. Upon exposure to oxidative stress, Nrf2 is dissociated from its inhibitor Keap-1 and translocated into the nucleus, where it results in the transcriptional activation of cell defense genes. Nrf2 has been demonstrated to be involved in the protection against foam cells formation by regulating the expression of antioxidant proteins (HO-1, Prxs, and GPx1), ATP-binding cassette (ABC) efflux transporters (ABCA1 and ABCG1) and scavenger receptors (scavenger receptor class B (CD36), scavenger receptor class A (SR-A) and lectin-type oxidized LDL receptor (LOX-1)). However, Nrf2 has also been reported to exhibit pro-atherogenic effects. A better understanding on the mechanism of Nrf2 in oxidative stress-induced cardiac injury, as well as the regulation of cholesterol uptake and efflux, are required before it can serve as a novel therapeutic target for cardiovascular diseases prevention and treatment.

Oxidative Stress in Cardiovascular Diseases: Involvement of Nrf2 Antioxidant Redox Signaling in Macrophage Foam Cells Formation

Oxidative stress is an important risk factor contributing to the pathogenesis of cardiovascular diseases. Oxidative stress that results from excessive reactive oxygen species (ROS) production accounts for impaired endothelial function, a process which promotes atherosclerotic lesion or fatty streaks formation (foam cells). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor involved in cellular redox homeostasis. Upon exposure to oxidative stress, Nrf2 is dissociated from its inhibitor Keap-1 and translocated into the nucleus, where it results in the transcriptional activation of cell defense genes. Nrf2 has been demonstrated to be involved in the protection against foam cells formation by regulating the expression of antioxidant proteins (HO-1, Prxs, and GPx1), ATP-binding cassette (ABC) efflux transporters (ABCA1 and ABCG1) and scavenger receptors (scavenger receptor class B (CD36), scavenger receptor class A (SR-A) and lectin-type oxidized LDL receptor (LOX-1)). However, Nrf2 has also been reported to exhibit pro-atherogenic effects. A better understanding on the mechanism of Nrf2 in oxidative stress-induced cardiac injury, as well as the regulation of cholesterol uptake and efflux, are required before it can serve as a novel therapeutic target for cardiovascular diseases prevention and treatment.

Endothelial adenosine A2a receptor-mediated glycolysis is essential for pathological retinal angiogenesis

Adenosine/adenosine receptor-mediated signaling has been implicated in the development of various ischemic diseases, including ischemic retinopathies. Here, we show that the adenosine A2a receptor (ADORA2A) promotes hypoxia-inducible transcription factor-1 (HIF-1)-dependent endothelial cell glycolysis, which is crucial for pathological angiogenesis in proliferative retinopathies. Adora2a expression is markedly increased in the retina of mice with oxygen-induced retinopathy (OIR). Endothelial cell-specific, but not macrophage-specific Adora2a deletion decreases key glycolytic enzymes and reduces pathological neovascularization in the OIR mice. In human primary retinal microvascular endothelial cells, hypoxia induces the expression of ADORA2A by activating HIF-2α. ADORA2A knockdown decreases hypoxia-induced glycolytic enzyme expression, glycolytic flux, and endothelial cell proliferation, sprouting and tubule formation. Mechanistically, ADORA2A activation promotes the transcriptional induction of glycolytic enzymes via ERK- and Akt-dependent translational activation of HIF-1α protein. Taken together, these findings advance translation of ADORA2A as a therapeutic target in the treatment of proliferative retinopathies and other diseases dependent on pathological angiogenesis.Pathological angiogenesis in the retina is a major cause of blindness. Here the authors show that adenosine receptor A2A drives pathological angiogenesis in the oxygen-induced retinopathy mouse model by promoting glycolysis in endothelial cells via the ERK/Akt/HIF-1α pathway, thereby suggesting new therapeutic targets for disease treatment.

High glucose-induced p53 phosphorylation contributes to impairment of endothelial antioxidant system

High levels of glucose (HG) induce reactive oxygen species-mediated oxidative stress in endothelial cells (ECs), which leads to endothelial dysfunction and tissue damage. However, the molecular mechanisms involved in HG-induced endothelial oxidative stress and damage remain elusive. Here we show that cellular ATP level-modulated p53 Thr55 phosphorylation plays a critical role in the process. Upon HG exposure, the elevated ATP levels induced the kinase activity of TAF1 (TBP-associated factor 1), which leads to p53 Thr55 phosphorylation. The phosphorylation dissociates p53 from the glutathione peroxidase 1 (GPX1) promoter and results in reduction of GPX1 expression. Inhibition of TAF1-mediated p53 Thr55 phosphorylation abolished those events, supporting the role of TAF1 in sensing cellular ATP elevation and in regulating GPX1 expression under the HG condition. Importantly, treating cells with HG increased intracellular H₂O₂ and cell apoptosis, as well as suppressed nitric oxide (NO) bioavailability and tube network formation. These effects were also remarkably reversed by inhibition of TAF1 and p53 Thr55 phosphorylation. We conclude that HG leads to endothelial dysfunction via TAF1-mediated p53 Thr55 phosphorylation and subsequent GPX1 inactivation. Our study thus revealed a novel mechanism by which HG induces endothelial oxidative stress and damage and possibly provided an avenue for targeted therapy for diabetes-associated cardiovascular diseases.

Oxidative stress and reactive oxygen species in endothelial dysfunction associated with cardiovascular and metabolic diseases

Reactive oxygen species (ROS) are reactive intermediates of molecular oxygen that act as important second messengers within the cells; however, an imbalance between generation of reactive ROS and antioxidant defense systems represents the primary cause of endothelial dysfunction, leading to vascular damage in both metabolic and atherosclerotic diseases. Endothelial activation is the first alteration observed, and is characterized by an abnormal pro-inflammatory and pro-thrombotic phenotype of the endothelial cells lining the lumen of blood vessels. This ultimately leads to reduced nitric oxide (NO) bioavailability, impairment of the vascular tone and other endothelial phenotypic changes collectively termed endothelial dysfunction(s). This review will focus on the main mechanisms involved in the onset of endothelial dysfunction, with particular focus on inflammation and aberrant ROS production and on their relationship with classical and non-classical cardiovascular risk factors, such as hypertension, metabolic disorders, and aging. Furthermore, new mediators of vascular damage, such as microRNAs, will be discussed. Understanding mechanisms underlying the development of endothelial dysfunction is an important base of knowledge to prevent vascular damage in metabolic and cardiovascular diseases.

Glutathione Peroxidase-1 Suppresses the Unfolded Protein Response upon Cigarette Smoke Exposure

Oxidative stress provokes endoplasmic reticulum (ER) stress-induced unfolded protein response (UPR) in the lungs of chronic obstructive pulmonary (COPD) subjects. The antioxidant, glutathione peroxidase-1 (GPx-1), counters oxidative stress induced by cigarette smoke exposure. Here, we investigate whether GPx-1 expression deters the UPR following exposure to cigarette smoke. Expression of ER stress markers was investigated in fully differentiated normal human bronchial epithelial (NHBE) cells isolated from nonsmoking, smoking, and COPD donors and redifferentiated at the air liquid interface. NHBE cells from COPD donors expressed heightened ATF4, XBP1, GRP78, GRP94, EDEM1, and CHOP compared to cells from nonsmoking donors. These changes coincided with reduced GPx-1 expression. Reintroduction of GPx-1 into NHBE cells isolated from COPD donors reduced the UPR. To determine whether the loss of GPx-1 expression has a direct impact on these ER stress markers during smoke exposure, Gpx-1-/- mice were exposed to cigarette smoke for 1 year. Loss of Gpx-1 expression enhanced cigarette smoke-induced ER stress and apoptosis. Equally, induction of ER stress with tunicamycin enhanced antioxidant expression in mouse precision-cut lung slices. Smoke inhalation also exacerbated the UPR response during respiratory syncytial virus infection. Therefore, ER stress may be an antioxidant-related pathophysiological event in COPD.

Role of adipokinetic hormone and adenosine in the anti-stress response in Drosophila melanogaster

The role of adipokinetic hormone (AKH) and adenosine in the anti-stress response was studied in Drosophila melanogaster larvae and adults carrying a mutation in the Akh gene (Akh(1)), the adenosine receptor gene (AdoR(1)), or in both of these genes (Akh(1) AdoR(1) double mutant). Stress was induced by starvation or by the addition of an oxidative stressor paraquat (PQ) to food. Mortality tests revealed that the Akh(1) mutant was the most resistant to starvation, while the AdoR(1) mutant was the most sensitive. Conversely, the Akh(1) AdoR(1) double mutant was more sensitive to PQ toxicity than either of the single mutants. Administration of PQ significantly increased the Drome-AKH level in w(1118) and AdoR(1) larvae; however, this was not accompanied by a simultaneous increase in Akh gene expression. In contrast, PQ significantly increased the expression of the glutathione S-transferase D1 (GstD1) gene. The presence of both a functional adenosine receptor and AKH seem to be important for the proper control of GstD1 gene expression under oxidative stress, however, the latter appears to play more dominant role. On the other hand, differences in glutathione S-transferase (GST) activity among the strains, and between untreated and PQ-treated groups were minimal. In addition, the glutathione level was significantly lower in all untreated AKH- or AdoR-deficient mutant flies as compared with the untreated control w(1118) flies and further declined following treatment with PQ. All oxidative stress characteristics modified by mutations in Akh gene were restored or even improved by 'rescue' mutation in flies which ectopically express Akh. Thus, the results of the present study demonstrate the important roles of AKH and adenosine in the anti-stress response elicited by PQ in a D. melanogaster model, and provide the first evidence for the involvement of adenosine in the anti-oxidative stress response in insects.

CUEDC2 modulates cardiomyocyte oxidative capacity by regulating GPX1 stability

The irreversible loss of cardiomyocytes due to oxidative stress is the main cause of heart dysfunction following ischemia/reperfusion (I/R) injury and ageing-induced cardiomyopathy. Here, we report that CUEDC2, a CUE domain-containing protein, plays a critical role in oxidative stress-induced cardiac injury. Cuedc2(-/-) cardiomyocytes exhibited a greater resistance to oxidative stress-induced cell death. Loss of CUEDC2 enhanced the antioxidant capacity of cardiomyocytes, promoted reactive oxygen species (ROS) scavenging, and subsequently inhibited the redox-dependent activation of signaling pathways. Notably, CUEDC2 promoted E3 ubiquitin ligases tripartite motif-containing 33 (TRIM33)-mediated the antioxidant enzyme, glutathione peroxidase 1 (GPX1) ubiquitination, and proteasome-dependent degradation. Ablation of CUEDC2 upregulated the protein level of GPX1 in the heart significantly. Strikingly, in vivo, the infarct size of Cuedc2(-/-) heart was significantly decreased after I/R injury, and aged Cuedc2(-/-) mice preserved better heart function as the overall ROS levels in their hearts were significantly lower. Our results demonstrated a novel role of CUEDC2 in cardiomyocyte death regulation. Manipulating CUEDC2 level might be an attractive therapeutic strategy for promoting cardiomyocyte survival following oxidative stress-induced cardiac injury.

Involvement of the Antioxidant Effect and Anti-inflammatory Response in Butyrate-Inhibited Vascular Smooth Muscle Cell Proliferation

Epigenetic mechanisms by altering the expression and, in turn, functions of target genes have potential to modify cellular processes that are characteristics of atherosclerosis, including inflammation, proliferation, migration and apoptosis/cell death. Butyrate, a natural epigenetic modifier and a histone deacetylase inhibitor (HDACi), is an inhibitor of vascular smooth muscle cell (VSMC) proliferation, a critical event in atherogenesis. Here, we examined whether glutathione peroxidases (GPxs), a family of antioxidant enzymes, are modulated by butyrate, contributing to its antiproliferation action on VSMC through the regulation of the inflammatory response by using western blotting, immunostaining methods and activity assay. Treatment of VSMC with butyrate not only upregulates glutathione peroxidase (GPx) 3 and GPx4, but also increases the overall catalytic activity of GPx supporting involvement of antioxidant effect in butyrate arrested VSMC proliferation. Moreover, analysis of the redox-sensitive NF-κB transcription factor system, the target of GPx, reveals that butyrate causes downregulation of IKKα, IKKβ, IkBα and NF-κBp65 expression and prevents NF-κBp65 phosphorylation at serine536 causing inhibition of the expression NF-κB target inflammatory genes, including inducible nitric oxide synthase, VCAM-1 and cyclooxygenase-2. Overall, these observations suggest a link between the antioxidant effect and anti-inflammatory response in butyrate-arrested VSMC proliferation, accentuating the atheroprotective and therapeutic potential of natural products, like butyrate, in vascular proliferative diseases.

PTEN phosphorylation and nuclear export mediate free fatty acid-induced oxidative stress

AIM

Oxidative stress induced by free fatty acids (FFA) contributes to metabolic syndrome-associated development of cardiovascular diseases, yet molecular mechanisms remain poorly understood. This study aimed at establishing whether phosphatase and tensin homolog deleted on chromosome 10 (PTEN) and its subcellular location play a role in FFA-induced endothelial oxidative stress.

RESULTS

Exposing human endothelial cells (ECs) with FFA activated mammalian target of rapamycin (mTOR)/S6K pathway, and upon activation, S6K directly phosphorylated PTEN at S380. Phosphorylation of PTEN increased its interaction with its deubiquitinase USP7 in the nucleus, leading to PTEN deubiquitination and nuclear export. The reduction of PTEN in the nucleus, in turn, decreased p53 acetylation and transcription, reduced the expression of the p53 target gene glutathione peroxidase-1 (GPX1), resulting in reactive oxygen species (ROS) accumulation and endothelial damage. Finally, C57BL/6J mice fed with high-fat atherogenic diet (HFAD) showed PTEN nuclear export, decreased p53 and GPX1 protein expressions, elevated levels of ROS, and significant lesions in aortas. Importantly, inhibition of mTOR or S6K effectively blocked these effects, suggesting that mTOR/S6K pathway mediates HFAD-induced oxidative stress and vascular damage via PTEN/p53/GPX1 inhibition in vivo.

INNOVATION

Our study demonstrated for the first time that S6K directly phosphorylated PTEN at S380 under high FFA conditions, and this phosphorylation mediated FFA-induced endothelial oxidative stress. Furthermore, we showed that S380 phosphorylation affected PTEN monoubiquitination and nuclear localization, providing the first example of coordinated regulation of PTEN nuclear localization via phosphorylation and ubiquitination.

CONCLUSION

Our studies provide a novel mechanism by which hyperlipidemia causes vascular oxidative damage through the phosphorylation of PTEN, blocking of PTEN nuclear function, and inhibition of p53/GPX1 activity.

Activation of adenosine receptors improves renal antioxidant status in diabetic Wistar but not SHR rats

BACKGROUND

Diabetes and hypertension independently contribute to renal injury, and the major mechanisms involved are increased reactive oxygen species (ROS) bioavailability and renin-angiotensin system (RAS) activation. We investigated the role of adenosine in controlling ROS production and RAS activation associated with renal dysfunction in hypertension and diabetes.

METHODS

Fourteen days after induction of diabetes with streptozotocin in 12-week-old male Wistar and spontaneously hypertensive (SHR) rats, animals were treated during 7 days with 2-chloroadenosine (CADO group, 5 mg/kg/d), a stable analogue of adenosine, or underwent a sham operation procedure. At the end of the study (day 21), intra-arterial systolic blood pressure (SBP) was measured, and 24-h urine and plasma samples and renal tissue were collected.

RESULTS

CADO treatment decreased the plasma glucose concentration and glucose and protein excretion by more than 30% in both strains. CADO treatment decreased SBP in diabetic SHR rats (143 ± 8 versus 114 ± 4 mmHg, p < 0.05), but not in diabetic Wistar rats. The hypotensive effect of CADO was associated to a ∼70% increase in plasma angiotensinogen (AGT) concentration and a ∼50% decrease in urinary AGT excretion. CADO also caused a decrease in medullary and cortical hydrogen peroxide production of about 40%, which was associated with a proportional increase in glutathione peroxidase (GPx) activity in diabetic Wistar but not in diabetic SHR animals.

CONCLUSIONS

These results suggest that activation of adenosine receptors improves renal antioxidant capacity in diabetic Wistar but not SHR rats, although it improves glucose metabolism in both strains. Furthermore, activation of adenosine receptors does not seem to be directly influencing AGT production.

Endothelial dysfunction - a major mediator of diabetic vascular disease

The vascular endothelium is a multifunctional organ and is critically involved in modulating vascular tone and structure. Endothelial cells produce a wide range of factors that also regulate cellular adhesion, thromboresistance, smooth muscle cell proliferation, and vessel wall inflammation. Thus, endothelial function is important for the homeostasis of the body and its dysfunction is associated with several pathophysiological conditions, including atherosclerosis, hypertension and diabetes. Patients with diabetes invariably show an impairment of endothelium-dependent vasodilation. Therefore, understanding and treating endothelial dysfunction is a major focus in the prevention of vascular complications associated with all forms of diabetes mellitus. The mechanisms of endothelial dysfunction in diabetes may point to new management strategies for the prevention of cardiovascular disease in diabetes. This review will focus on the mechanisms and therapeutics that specifically target endothelial dysfunction in the context of a diabetic setting. Mechanisms including altered glucose metabolism, impaired insulin signaling, low-grade inflammatory state, and increased reactive oxygen species generation will be discussed. The importance of developing new pharmacological approaches that upregulate endothelium-derived nitric oxide synthesis and target key vascular ROS-producing enzymes will be highlighted and new strategies that might prove clinically relevant in preventing the development and/or retarding the progression of diabetes associated vascular complications.

Cardiovascular protection and antioxidant activity of the extracts from the mycelia of Cordyceps sinensis act partially via adenosine receptors

Mycelia of cultured Cordyceps sinensis (CS) is one of the most common substitutes for natural CS and was approved for arrhythmia in China. However, the role of CS in ameliorating injury during ischemia-reperfusion (I/R) is still unclear. We examined effects of extracts from CS on I/R and investigated the possible mechanisms. Post-ischemic coronary perfusion pressure, ventricular function, and coronary flow were measured using the Langendorff mouse heart model. Oxidative stress of cardiac homogenates was performed using an ELISA. Our results indicate that CS affords cardioprotection possibly through enhanced adenosine receptor activation. Cardioprotection was demonstrated by reduced post-ischemic diastolic dysfunction and improved recovery of pressure development and coronary flow. Treatment with CS largely abrogates oxidative stress and damage in glucose- or pyruvate-perfused hearts. Importantly, observed reductions in oxidative stress [glutathione disulfide (GSSG)]/[GSSG + glutathione] and [malondialdehyde (MDA)]/[superoxide dismutase + MDA] ratios as well as the resultant damage upon CS treatment correlate with functional markers of post-ischemic myocardial outcome. These effects of CS were partially blocked by 8-ρ-sulfophenyltheophylline, an adenosine receptor antagonist. Our results demonstrate a suppressive role of CS in ischemic contracture. Meanwhile, the results also suggest pre-ischemic adenosine receptor activation may be involved in reducing contracture in hearts pretreated with CS.

Involvement of P2Y receptors in the protective effect of ATP towards the cell damage in HaCaT cells exposed to H₂O₂

It has recently been reported that activation of P2Y(1) receptor, one of the purine receptors, by extracellular nucleotides induces cytoprotection against oxidative stress. In this study, we examined the protective effect of ATP on the cell damage in human epidermal keratinocyte HaCaT cells exposed to H(2)O(2) via the P2Y receptor-mediated induction of intracellular antioxidants. The cells were damaged by exposure to H(2)O(2) in a dose- and time-dependent manner. The damage induced by 7.5 mM H(2)O(2) was blocked by pretreatment of the cells with ATP (1-10 µM). The protective effect of ATP was significantly reduced by P2Y receptor antagonists. Exogenously added ATP induced various intracellular antioxidants, including thiol-containing proteins, Cu/Zn superoxide dismutase (SOD) and thioredoxin-1, in HaCaT cells. In conclusion, it was found that ATP protected the cells from the H(2)O(2)-induced cell damages via the P2Y receptor-mediated induction of intracellular antioxidants.

Effect of selenium supplementation on glutathione peroxidase and catalase activities in senescent cultured human fibroblasts

AIMS

To investigate the effect of senescence and selenium supplementation on glutathione peroxidase (cGPx) and catalase (CAT) activities, and concurrent hydrogen peroxide (H(2)O(2)) generation in subcultured human fibroblasts.

METHODS

cGPx and CAT activities and H(2)O(2) levels were assayed in presenescent passage 5 and 10 cells, and in senescent passage 20, 25, 30 and 35 cells cultured in routine medium (MEM1) and supplemented media MEM2 and MEM3 containing normal and triple human plasma levels of Se, respectively. Senescent cells were identified by studying their growth and replication states, and by monitoring their activity of key glucose and glycogen degradative enzymes.

RESULTS

cGPx activity showed moderate increases in senescent cells at passages 20-35 subcultured in MEM1 or MEM2. This activity underwent highly significant progressive increases in the same senescent cells subcultured in MEM3. In contrast, CAT activity showed progressive, highly significant increases in senescent cells at passages 20-35 regardless of the culture medium type. Concurrent H(2)O(2) generation was significantly increased in passage 15-25 cells and peaked to higher levels in passage 30 and 35 cells cultured in MEM1 or MEM2. These rates, however, were significantly reduced in senescent passage 20-35 cells cultured in MEM3.

CONCLUSIONS

The highest cGPx activity and coupled lower H(2)O(2) generation were achieved in senescent cells cultured in MEM3.

Glutathione peroxidase-1 deficiency augments proinflammatory cytokine-induced redox signaling and human endothelial cell activation

Glutathione peroxidase-1 (GPx-1) is a crucial antioxidant enzyme, the deficiency of which promotes atherogenesis. Accordingly, we examined the mechanisms by which GPx-1 deficiency enhances endothelial cell activation and inflammation. In human microvascular endothelial cells, we found that GPx-1 deficiency augments intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression by redox-dependent mechanisms that involve NFκB. Suppression of GPx-1 enhanced TNF-α-induced ROS production and ICAM-1 expression, whereas overexpression of GPx-1 attenuated these TNF-α-mediated responses. GPx-1 deficiency prolonged TNF-α-induced IκBα degradation and activation of ERK1/2 and JNK. JNK or NFκB inhibition attenuated TNF-α induction of ICAM-1 and VCAM-1 expression in GPx-1-deficient and control cells, whereas ERK1/2 inhibition attenuated only VCAM-1 expression. To analyze further signaling pathways involved in GPx-1-mediated protection from TNF-α-induced ROS, we performed microarray analysis of human microvascular endothelial cells treated with TNF-α in the presence and absence of GPx-1. Among the genes whose expression changed significantly, dual specificity phosphatase 4 (DUSP4), encoding an antagonist of MAPK signaling, was down-regulated by GPx-1 suppression. Targeted DUSP4 knockdown enhanced TNF-α-mediated ERK1/2 pathway activation and resulted in increased adhesion molecule expression, indicating that GPx-1 deficiency may augment TNF-α-mediated events, in part, by regulating DUSP4.

Glutathione peroxidase-1 in health and disease: from molecular mechanisms to therapeutic opportunities

Reactive oxygen species, such as superoxide and hydrogen peroxide, are generated in all cells by mitochondrial and enzymatic sources. Left unchecked, these reactive species can cause oxidative damage to DNA, proteins, and membrane lipids. Glutathione peroxidase-1 (GPx-1) is an intracellular antioxidant enzyme that enzymatically reduces hydrogen peroxide to water to limit its harmful effects. Certain reactive oxygen species, such as hydrogen peroxide, are also essential for growth factor-mediated signal transduction, mitochondrial function, and maintenance of normal thiol redox-balance. Thus, by limiting hydrogen peroxide accumulation, GPx-1 also modulates these processes. This review explores the molecular mechanisms involved in regulating the expression and function of GPx-1, with an emphasis on the role of GPx-1 in modulating cellular oxidant stress and redox-mediated responses. As a selenocysteine-containing enzyme, GPx-1 expression is subject to unique forms of regulation involving the trace mineral selenium and selenocysteine incorporation during translation. In addition, GPx-1 has been implicated in the development and prevention of many common and complex diseases, including cancer and cardiovascular disease. This review discusses the role of GPx-1 in these diseases and speculates on potential future therapies to harness the beneficial effects of this ubiquitous antioxidant enzyme.

Adenosine deaminase activity in patients with Crohn's disease: distinction between active and nonactive disease

BACKGROUND

Crohn's disease (CD) is a common chronic inflammatory bowel disease. During the disease a cascade of immunologic events occur including mucosal influx of inflammatory cells like neutrophils. Adenosine deaminase (ADA) is important in inflammatory responses and serves as a marker of activated leukocytes.

MATERIALS AND METHODS

In this study, we investigated the activity of total ADA (tADA) and its isoenzymes, ADA1 and ADA2, in serum and neutrophils derived from 20 active patients with CD, 20 patients in remission, as well as in 15 healthy controls.

RESULTS

Patients with active disease had significantly (P<0.001) higher levels of tADA in serum (22.9±4.9 U/l) than patients in remission or healthy controls (14.0±3.4 U/l and 13.2±2.4 U/l respectively). ADA2, the main isoenzyme in the serum was higher in active patients by 60% as compared with patients in remission and healthy controls (19.7±1.9 U/l, 12.3±1.2 U/l, and 12.2±0.9 U/l respectively). We did not find a significant difference in these parameters between healthy controls and stable patients. There was a positive correlation (R=0.516) between tADA activity and C-reactive protein levels in patients with CD. Enhanced activity in tADA was also detected in neutrophils that were obtained from all patients with CD as compared with healthy controls (15.3±2.9 U/g, 14.1±2.3 U/g, and 9.4±2.9 U/g protein, respectively). This is mainly due to a significant increment (up to 51%) in ADA1 activity, the main isoenzyme in the neutrophils (84% out of the tADA). The cause of this increment remains to be elucidated.

CONCLUSION

The results obtained in this study demonstrated elevated levels of tADA and ADA2 in patients with active disease. As the patient improves and becomes clinically stable these levels decrease, approaching normal values. tADA and ADA2 can be used as markers of inflammation, and provide a supportive indicator of CD activity.

Glutathione peroxidase-1 modulates lipopolysaccharide-induced adhesion molecule expression in endothelial cells by altering CD14 expression

CD14 contributes to LPS signaling in leukocytes through formation of toll-like receptor 4/CD14 receptor complexes; however, a specific role for endogenous cell-surface CD14 in endothelial cells is unclear. We have found that suppression of glutathione peroxidase-1 (GPx-1) in human microvascular endothelial cells increases CD14 gene expression compared to untreated or siControl (siCtrl)-treated conditions. Following LPS treatment, GPx-1 deficiency augmented LPS-induced intracellular reactive oxygen species accumulation, CD14 expression, and intercellular adhesion molecule-1 (ICAM-1) mRNA and protein expression compared to LPS-treated control cells. GPx-1 deficiency also transiently augmented LPS-induced vascular cell adhesion molecule-1 (VCAM-1) expression. Adenoviral overexpression of GPx-1 significantly diminished LPS-mediated responses in adhesion molecule expression. Consistent with these findings, LPS responses were also greater in endothelial cells derived from GPx-1-knockout mice, whereas adhesion molecule expression was decreased in cells from GPx-1-overexpressing transgenic mice. Knockdown of CD14 attenuated LPS-mediated up-regulation of ICAM-1 and VCAM-1 mRNA and protein, and it mitigated the effects of GPx-1 deficiency on LPS-induced adhesion molecule expression. Taken together, these data suggest that GPx-1 modulates the endothelial cell response to LPS, in part, by altering CD14-mediated effects.

Involvement of reductive stress in the cardiomyopathy in transgenic mice with cardiac-specific overexpression of heat shock protein 27

Oxidative stress plays an important role in cardiac diseases, which has been well demonstrated, whereas the role of reductive stress has been poorly investigated. We and others have shown previously that heat shock protein 27 (Hsp27) plays a role as an antioxidant. To investigate whether overexpression of Hsp27 could lead to reductive stress and result in cardiomyopathy, we generated transgenic mice with different expression levels of Hsp27. We observed that transgenic mice with high levels of Hsp27 developed cardiomyopathy. The myopathic hearts were under reductive stress, which was evidenced by an increased ratio of reduced glutathione/oxidized glutathione and a decreased level of reactive oxygen species. In addition, upregulated glutathione peroxidase 1 and decreased iron content were revealed in the myopathic hearts. More importantly, inhibition of glutathione peroxidase 1 significantly attenuated the development of cardiomyopathy. The data indicate that the Hsp27-induced cardiomyopathy could be attributed to, at least in part, upregulation of glutathione peroxidase 1. Our findings suggest that reductive stress plays an important role in the development of cardiomyopathy and that Hsp27 may serve as a potential target for the treatment of patients with cardiomyopathy.

Glutathione peroxidases in different stages of carcinogenesis

Cancer cells produce high amounts of reactive oxygen species (ROS) and evade apoptosis. Hydroperoxides support proliferation, invasion, migration and angiogenesis, but at higher levels induce apoptosis, thus being pro- and anti-carcinogenic. Accordingly, glutathione peroxidases (GPxs) regulating hydroperoxide levels might have dual roles too. GPx1, clearly an antioxidant enzyme, is down-regulated in many cancer cells. Its main role would be prevention of cancer initiation by ROS-mediated DNA damage. GPx2 is up-regulated in cancer cells. GPx1/GPx2 double knockout mice develop colitis and intestinal cancer. However, GPx2 knockdown cancer cells grow better in vitro and in vivo probably reflecting the physiological role of GPx2 in intestinal mucosa homeostasis. GPx2 counteracts COX-2 expression and PGE(2) production, which explains its potential to inhibit migration and invasion of cultured cancer cells. Overexpression of GPx3 inhibits tumor growth and metastasis. GPx4 is decreased in cancer tissues. GPx4-overexpressing cancer cells have low COX-2 activity and tumors derived therefrom are smaller than from control cells and do not metastasize. Collectively, GPxs prevent cancer initiation by removing hydroperoxides. GPx4 inhibits but GPx2 supports growth of established tumors. Metastasis, but also apoptosis, is inhibited by all GPxs. GPx-mediated regulation of COX/LOX activities may be relevant to early stages of inflammation-mediated carcinogenesis.

Glutathione peroxidase-1 regulates mitochondrial function to modulate redox-dependent cellular responses

Glutathione peroxidase-1 (GPx-1) is a selenocysteine-containing enzyme that plays a major role in the reductive detoxification of peroxides in cells. In permanently transfected cells with approximate 2-fold overexpression of GPx-1, we found that intracellular accumulation of oxidants in response to exogenous hydrogen peroxide was diminished, as was epidermal growth factor receptor (EGFR)-mediated Akt activation in response to hydrogen peroxide or EGF stimulation. Knockdown of GPx-1 augmented EGFR-mediated Akt activation, whereas overexpression of catalase decreased Akt activation, suggesting that EGFR signaling is regulated by redox mechanisms. To determine whether mitochondrial oxidants played a role in these processes, cells were pretreated with a mitochondrial uncoupler prior to EGF stimulation. Inhibition of mitochondrial function attenuated EGF-mediated activation of Akt in control cells but had no additional effect in GPx-1-overexpressing cells, suggesting that GPx-1 overexpression decreased EGFR signaling by decreasing mitochondrial oxidants. Consistent with this finding, GPx-1 overexpression decreased global protein disulfide bond formation, which is dependent on mitochondrially produced oxidants. GPx-1 overexpression, in permanently transfected or adenovirus-treated cells, also caused overall mitochondrial dysfunction with a decrease in mitochondrial potential and a decrease in ATP production. GPx-1 overexpression also decreased EGF- and serum-mediated [(3)H]thymidine incorporation, indicating that alterations in GPx-1 can attenuate cell proliferation. Taken together, these data suggest that GPx-1 can modulate redox-dependent cellular responses by regulating mitochondrial function.

Redox control of endothelial function and dysfunction: molecular mechanisms and therapeutic opportunities

The endothelium is essential for the maintenance of vascular homeostasis. Central to this role is the production of endothelium-derived nitric oxide (EDNO), synthesized by the endothelial isoform of nitric oxide synthase (eNOS). Endothelial dysfunction, manifested as impaired EDNO bioactivity, is an important early event in the development of various vascular diseases, including hypertension, diabetes, and atherosclerosis. The degree of impairment of EDNO bioactivity is a determinant of future vascular complications. Accordingly, growing interest exists in defining the pathologic mechanisms involved. Considerable evidence supports a causal role for the enhanced production of reactive oxygen species (ROS) by vascular cells. ROS directly inactivate EDNO, act as cell-signaling molecules, and promote protein dysfunction, events that contribute to the initiation and progression of endothelial dysfunction. Increasing data indicate that strategies designed to limit vascular ROS production can restore endothelial function in humans with vascular complications. The purpose of this review is to outline the various ways in which ROS can influence endothelial function and dysfunction, describe the redox mechanisms involved, and discuss approaches for preventing endothelial dysfunction that may highlight future therapeutic opportunities in the treatment of cardiovascular disease.

Assessment of genetic risk factors for thoracic aortic aneurysm in hypertensive patients

BACKGROUND

Conventional risk factors for thoracic aortic aneurysm including dissection (TAA) are thought to include age, arteriosclerosis, and hypertension. In addition, evidence suggests that genetic factors play a role in the development of this condition. The purpose of the present study was to identify genetic variants that confer susceptibility to TAA in hypertensive subjects.

METHODS

Study subjects comprised 1,351 hypertensive individuals: 88 patients with TAA and 1,263 subjects without this condition. The genotypes for 142 polymorphisms of 119 candidate genes were determined by a method that combines the PCR and sequence-specific oligonucleotide probes with suspension array technology.

RESULTS

Evaluation of genotype distributions by the chi2-test and subsequent multivariable logistic regression analysis with adjustment for covariates revealed that the 3949T-->G (3' untranslated region) polymorphism of the thrombospondin-2 gene (THBS2; odds ratio, 4.6), the -110A-->C polymorphism of the heat shock 70-kDa protein 8 gene (HSPA8; odds ratio, 0.4), the C-->T (Pro198Leu) polymorphism of the glutathione peroxidase 1 gene (GPX1; odds ratio, 0.3), the -6G-->A polymorphism of the angiotensinogen gene (AGT; odds ratio, 0.3), and the -850C-->T polymorphism of the tumor necrosis factor gene (TNF; odds ratio, 0.5) were significantly (P < 0.05) associated with TAA.

CONCLUSIONS

The variant allele of THBS2 is a risk factor for TAA in hypertensive patients, whereas the variant alleles of HSPA8, GPX1, AGT, and TNF are protective against this condition. Determination of genotypes for these polymorphisms may prove informative for assessment of the genetic risk for TAA.

A2B adenosine receptor gene deletion attenuates murine colitis

BACKGROUND & AIMS

The A(2B) adenosine receptor (A(2B)AR) is the predominant adenosine receptor expressed in the colonic epithelia. We have previously shown that A(2B)AR mRNA and protein levels are up-regulated during colitis. In this study, we addressed the role of the A(2B)AR in the development of murine colitis and the potential mechanism underlying its effects.

METHODS

Dextran sodium sulfate (DSS), 2,4,6-trinitrobenzene sulfonic acid (TNBS), and Salmonella typhimurium were used to induce colitis in A(2B)AR-null mice (A(2B)AR(-/-)). Colitis was determined using established clinical and histologic scoring. Keratinocyte-derived chemokine (KC) measurements were performed using an enzyme-linked immunosorbent assay.

RESULTS

Colonic inflammation induced by DSS, TNBS, or S typhimurium was attenuated in A(2B)AR(-/-) compared with their wild-type counterparts. Clinical features, histologic score, and myeloperoxidase activity were significantly decreased in A(2B)AR(-/-) mice. However, A(2B)AR(-/-) showed increased susceptibility to systemic Salmonella infection. Tissue levels of the neutrophil chemokine, KC was decreased in colitic A(2B)AR(-/-) mice. In addition, flagellin-induced KC levels were attenuated in A(2B)AR(-/-) mice. Neutrophil chemotaxis in response to exogenous interleukin-8 was preserved in A(2B)AR(-/-) mice, suggesting intact neutrophil migration in response to appropriate stimuli.

CONCLUSIONS

These data demonstrate, for the first time, that the A(2B)AR plays a proinflammatory role in colitis. A(2B) receptor antagonism may be an effective treatment for acute inflammatory intestinal diseases such as acute flare of inflammatory bowel disease.

Role of superoxide and hydrogen peroxide in hypertension induced by an antagonist of adenosine receptors

Treatment of Wistar rats for 7 days with 1,3-dipropyl-8-sulfophenylxanthine (DPSPX), an antagonist of adenosine receptors, induces long-lasting hypertension associated with marked changes in vascular structure and reactivity and renin-angiotensin system activation. This study aimed at evaluating the role of oxidative stress in the development of DPSPX-induced hypertension and also at identifying the relative contribution of superoxide radical (O2.-) vs hydrogen peroxide (H2O2). Vascular and systemic prooxidant/antioxidant status was evaluated in sham (saline, i.p., 7 days) and DPSPX (90 microg/kg/h, i.p., 7 days)-treated rats. Systolic blood pressure was determined by invasive and non-invasive methods. The activity of vascular NADPH oxidase, superoxide dismutase (SOD), catalase and glutathione peroxidase was assayed by fluorometric/spectrophotometric methods. H2O2 levels were measured using an Amplex Red Hydrogen Peroxide kit. Plasma thiobarbituric acid reactive substances and plasma antioxidant capacity were also measured. In addition we tested the effects of antioxidants or inhibitors of reactive oxygen species generation on blood pressure, vascular hyperplasia and oxidative stress parameters. DPSPX-hypertensive rats showed increased activity of vascular NADPH oxidase, SOD, catalase and glutathione peroxidase, as well as increased H2O2 generation. DPSPX-hypertensive rats also had increased plasma lipid peroxidation and decreased plasma antioxidant capacity. Treatment with apocynin (1.5 mmol/l, per os, 14 days), or with polyethylene glycol (PEG)-catalase (10,000 U/kg/day, i.p., 8 days), prevented the DPSPX-induced effects on blood pressure, vascular structure and H2O2 levels. Tempol (3 mmol/l, per os, 14 days) failed to inhibit these changes, unless PEG-catalase was co-administered. It is concluded that O2.- generation with subsequent formation of H2O2 plays a major role in the development of DPSPX-induced hypertension.