Current concepts of redox signaling in the lungs

GSTP alleviates acute lung injury by S-glutathionylation of KEAP1 and subsequent activation of NRF2 pathway

Oxidative stress plays an important role in the pathogenesis of acute lung injury (ALI). As a typical post-translational modification triggered by oxidative stress, protein S-glutathionylation (PSSG) is regulated by redox signaling pathways and plays diverse roles in oxidative stress conditions. In this study, we found that GSTP downregulation exacerbated LPS-induced injury in human lung epithelial cells and in mice ALI models, confirming the protective effect of GSTP against ALI both in vitro and in vivo. Additionally, a positive correlation was observed between total PSSG level and GSTP expression level in cells and mice lung tissues. Further results demonstrated that GSTP inhibited KEAP1-NRF2 interaction by promoting PSSG process of KEAP1. By the integration of protein mass spectrometry, molecular docking, and site-mutation validation assays, we identified C434 in KEAP1 as the key PSSG site catalyzed by GSTP, which promoted the dissociation of KEAP1-NRF2 complex and activated the subsequent anti-oxidant genes. In vivo experiments with AAV-GSTP mice confirmed that GSTP inhibited LPS-induced lung inflammation by promoting PSSG of KEAP1 and activating the NRF2 downstream antioxidant pathways. Collectively, this study revealed the novel regulatory mechanism of GSTP in the anti-inflammatory function of lungs by modulating PSSG of KEAP1 and the subsequent KEAP1/NRF2 pathway. Targeting at manipulation of GSTP level or activity might be a promising therapeutic strategy for oxidative stress-induced ALI progression.

D-cysteine ethyl ester and D-cystine dimethyl ester reverse the deleterious effects of morphine on arterial blood-gas chemistry and Alveolar-arterial gradient in anesthetized rats

We determined whether intravenous injections of the membrane-permeable ventilatory stimulants, D-cysteine ethyl ester (ethyl (2 S)– 2-amino-3-sulfanylpropanoate) (D-CYSee) and D-cystine dimethyl ester (methyl (2 S)– 2-amino-3-[[(2 S)– 2-amino-3-methoxy-3-oxopropyl]disulfanyl] propanoate) (D-CYSdime), could overcome the deleterious actions of intravenous morphine on arterial blood pH, pCO₂, pO₂ and sO₂, and Alveolar-arterial (A-a) gradient (i.e., the measure of exchange of gases in the lungs) in Sprague Dawley rats anesthetized with isoflurane. Injection of morphine (2 mg/kg, IV) caused pronounced reductions in pH, pO₂ and sO₂ accompanied by elevations in pCO₂, all which are suggestive of diminished ventilation, and elevations in A-a gradient, which suggests a mismatch of ventilation-perfusion. Subsequent boluses of D-cysteine ethyl ester (2 × 100 μmol/kg, IV) or D-cystine dimethyl ester (2 ×50 μmol/kg, IV) rapidly reversed of the negative actions of morphine on pH, pCO₂, pO₂ and sO₂, and A-a gradient. Similar injections of D-cysteine (2 × 100 μmol/kg, IV) were without effect, whereas injections of D-cystine (2 × 50 μmol/kg, IV) produced a modest reversal. Our data show that D-cysteine ethyl ester and D-cystine dimethyl ester readily overcome the deleterious effects of morphine on arterial blood gas (ABG) chemistry and A-a gradient by mechanisms that may depend upon their ability to rapidly enter cells. As a result of their known ability to enter the brain, lungs, muscles of the chest wall, and most likely the major peripheral chemoreceptors (i.e., carotid bodies), the effects of the thiolesters on changes in ABG chemistry and A-a gradient elicited by morphine likely involve central and peripheral mechanisms. We are employing target prediction methods to identify an array of in vitro and in vivo methods to test potential functional proteins by which D-CYSee and D-CYSdime modulate the effects of morphine on breathing.

The Impact of Alcohol Use Disorder on Tuberculosis: A Review of the Epidemiology and Potential Immunologic Mechanisms

Globally, an estimated 107 million people have an alcohol use disorder (AUD) leading to 2.8 million premature deaths each year. Tuberculosis (TB) is one of the leading causes of death globally and over 8% of global TB cases are estimated to be attributable to AUD. Social determinants of health such as poverty and undernutrition are often shared among those with AUD and TB and could explain the epidemiologic association between them. However, recent studies suggest that these shared risk factors do not fully account for the increased risk of TB in people with AUD. In fact, AUD has been shown to be an independent risk factor for TB, with a linear increase in the risk for TB with increasing alcohol consumption. While few studies have focused on potential biological mechanisms underlying the link between AUD and TB, substantial overlap exists between the effects of alcohol on lung immunity and the mechanisms exploited by Mycobacterium tuberculosis (Mtb) to establish infection. Alcohol misuse impairs the immune functions of the alveolar macrophage, the resident innate immune effector in the lung and the first line of defense against Mtb in the lower respiratory tract. Chronic alcohol ingestion also increases oxidative stress in the alveolar space, which could in turn facilitate Mtb growth. In this manuscript, we review the epidemiologic data that links AUD to TB. We discuss the existing literature on the potential mechanisms by which alcohol increases the risk of TB and review the known effects of alcohol ingestion on lung immunity to elucidate other mechanisms that Mtb may exploit. A more in-depth understanding of the link between AUD and TB will facilitate the development of dual-disease interventions and host-directed therapies to improve lung health and long-term outcomes of TB.

Cigarette smoke and glutathione: Focus on in vitro cell models

Cigarette smoke (CS) is one of the most important preventable risk factors for the development of respiratory diseases, cardiovascular diseases, stroke, and various types of cancer. Due to its high intracellular concentration and central role in maintaining the cellular redox state, glutathione (GSH) is one of the key players in several enzymatic and non-enzymatic reactions necessary for protecting cells against CS-induced oxidative stress. A plethora of in vitro cell models have been used over the years to assess the effects of CS on intracellular GSH and its disulphide forms, i.e. glutathione disulphide (GSSG) and S-glutathionylated proteins. In this review, we described the effects of cell exposure to CS on cellular GSH and formation of its oxidized forms and adducts (GSH-conjugates). We also discussed the limitations and relevance of in vitro cell models of exposure to CS and critically assessed the congruence between smokers and in vitro cell models. What emerges clearly is that results obtained in vitro should be interpreted with extreme caution, bearing in mind the limitations of the specific cell model used. Despite this, in vitro cell models remain important tools in the assessment of CS-induced oxidative damage.

Regulation of the Proteolytic Activity of Cysteine Cathepsins by Oxidants

Besides their primary involvement in the recycling and degradation of proteins in endo-lysosomal compartments and also in specialized biological functions, cysteine cathepsins are pivotal proteolytic contributors of various deleterious diseases. While the molecular mechanisms of regulation via their natural inhibitors have been exhaustively studied, less is currently known about how their enzymatic activity is modulated during the redox imbalance associated with oxidative stress and their exposure resistance to oxidants. More specifically, there is only patchy information on the regulation of lung cysteine cathepsins, while the respiratory system is directly exposed to countless exogenous oxidants contained in dust, tobacco, combustion fumes, and industrial or domestic particles. Papain-like enzymes (clan CA, family C1, subfamily C1A) encompass a conserved catalytic thiolate-imidazolium pair (Cys25-His159) in their active site. Although the sulfhydryl group (with a low acidic pKa) is a potent nucleophile highly susceptible to chemical modifications, some cysteine cathepsins reveal an unanticipated resistance to oxidative stress. Besides an introductory chapter and peculiar attention to lung cysteine cathepsins, the purpose of this review is to afford a concise update of the current knowledge on molecular mechanisms associated with the regulation of cysteine cathepsins by redox balance and by oxidants (e.g., Michael acceptors, reactive oxygen, and nitrogen species).

Effect of Pycnogenol® on attention-deficit hyperactivity disorder (ADHD): study protocol for a randomised controlled trial

BACKGROUND

Methylphenidate (MPH), the first choice medication for attention-deficit hyperactivity disorder (ADHD), is associated with serious adverse effects like arrhythmia. Evidence on the association of ADHD with immune and oxidant-antioxidant imbalances offers potential for antioxidant and/or immunomodulatory nutritional supplements as ADHD therapy. One small randomised trial in ADHD suggests, despite various limitations, therapeutic benefit from Pycnogenol®, a herbal, polyphenol-rich extract.

METHODS

This phase III trial is a 10-week, randomised, double-blind, placebo and active treatment controlled multicentre trial with three parallel treatment arms to compare the effect of Pycnogenol® to MPH and placebo on the behaviour of 144 paediatric ADHD and attention-deficit disorder (ADD) patients. Evaluations of behaviour (measured by the ADHD-Rating Scale (primary endpoint) and the Social-emotional Questionnaire (SEQ)), immunity (plasma cytokine and antibody levels, white blood cell counts and faecal microbial composition), oxidative stress (erythrocyte glutathione, plasma lipid-soluble vitamins and malondialdehyde and urinary 8-OHdG levels, as well as antioxidant enzyme activity and gene expression), serum zinc and neuropeptide Y level, urinary catecholamines and physical complaints (Physical Complaints Questionnaire) will be performed in week 10 and compared to baseline. Acceptability evaluations will be based on adherence, dropouts and reports of adverse events. Dietary habits will be taken into account.

DISCUSSION

This trial takes into account comorbid behavioural and physical symptoms, as well as a broad range of innovative immune and oxidative biomarkers, expected to provide fundamental knowledge on ADHD aetiology and therapy. Research on microbiota in ADHD is novel. Moreover, the active control arm is rather unseen in research on nutritional supplements, but of great importance, as patients and parents are often concerned with the side effects of MPH.

TRIAL REGISTRATION

Clinicaltrials.gov number: NCT02700685 . Registered on 18 January 2016. EudraCT 2016-000215-32 . Registered on 4 October 2016.

Redox-Dependent Calpain Signaling in Airway and Pulmonary Vascular Remodeling in COPD

The calcium-dependent cytosolic, neutral, thiol endopeptidases, calpains, perform limited cleavage of their substrates thereby irreversibly changing their functions. Calpains have been shown to be involved in several physiological processes such as cell motility, proliferation, cell cycle, signal transduction, and apoptosis. Overactivation of calpain or mutations in the calpain genes contribute to a number of pathological conditions including neurodegenerative disorders, rheumatoid arthritis, cancer, and lung diseases. High concentrations of reactive oxygen and nitrogen species (RONS) originated from cigarette smoke or released by numerous cell types such as activated inflammatory cells and other respiratory cells cause oxidative and nitrosative stress contributing to the pathogenesis of COPD. RONS and calpain play important roles in the development of airway and pulmonary vascular remodeling in COPD. Published data show that increased RONS production is associated with increased calpain activation and/or elevated calpain protein level, leading to epithelial or endothelial barrier dysfunction, neovascularization, lung inflammation, increased smooth muscle cell proliferation, and deposition of extracellular matrix protein. Further investigation of the redox-dependent calpain signaling may provide future targets for the prevention and treatment of COPD.

Role of reactive oxygen species and TRP channels in the cough reflex

The cough reflex is evoked by noxious stimuli in the airways. Although this reflex is essential for health, it can be triggered chronically in inflammatory and infectious airway disease. Neuronal transient receptor potential (TRP) channels such as ankyrin 1 (TRPA1) and vanilloid 1 (TRPV1) are polymodal receptors expressed on airway nociceptive afferent nerves. Reactive oxygen species (ROS) and other reactive compounds are associated with inflammation, from either NADPH oxidase or mitochondria. These reactive compounds cause activation and hyperexcitability of nociceptive afferents innervating the airways, and evidence suggests key contributions of TRPA1 and TRPV1.

Air pollution, physical activity, and markers of acute airway oxidative stress and inflammation in adolescents

BACKGROUND

The airway inflammatory response is likely the mechanism for adverse health effects related to exposure to air pollution. Increased ventilation rates during physical activity in the presence of air pollution increases the inhaled dose of pollutants. However, physical activity may moderate the relationship between air pollution and the inflammatory response. The present study aimed to characterize, among healthy adolescents, the relationship between dose of inhaled air pollution, physical activity, and markers of lung function, oxidative stress, and airway inflammation.

METHODS

With a non-probability sample of adolescents, this observational study estimated the association between air pollution dose and outcome measures by use of general linear mixed models with an unstructured covariance structure and a random intercept for subjects to account for repeated measures within subjects.

RESULTS

A one interquartile range (IQR) (i.e., 345.64 μg) increase in ozone (O3) inhaled dose was associated with a 29.16% average decrease in the percentage of total oxidized compounds (%Oxidized). A one IQR (i.e., 2.368E+10 particle) increase in total particle number count in the inhaled dose (PNT) was associated with an average decrease in forced expiratory flow (FEF25-75) of 0.168 L/second. Increasing activity levels attenuated the relationship between PNT inhaled dose and exhaled nitric oxide (eNO). The relationship between O3 inhaled dose and percent oxidized exhaled breath condensate cystine (%CYSS) was attenuated by activity level, with increasing activity levels corresponding to smaller changes from baseline for a constant O3 inhaled dose.

CONCLUSIONS

The moderating effects of activity level suggest that peaks of high concentration doses of air pollution may overwhelm the endogenous redox balance of cells, resulting in increased airway inflammation. Further research that examines the relationships between dose peaks over time and inflammation could help to determine whether a high concentration dose over a short period of time has a different effect than a lower concentration dose over a longer period of time.

Oxygen differentially affects the hox proteins Hoxb5 and Hoxa5 altering airway branching and lung vascular formation

Hoxb5 and Hoxa5 transcription factor proteins uniquely impact lung morphogenesis at the developmental time point when extremely preterm infants are born. The effect of O2 exposure (0.4 FiO2) used in preterm infant care on these Hox proteins is unknown. We used ex vivo fetal mouse lung organ cultures to explore the effects of 0.4 FiO2 on lung airway and vascular formation in the context of Hoxb5 and Hoxa5 expression and regulation. Compared to room air, 48 h (h) 0.4 FiO2 adversely attenuated airway and microvasculature formation while reducing lung growth and epithelial cell volume, and increasing mesenchymal volume. 0.4 FiO2 decreased pro-angiogenic Hoxb5 and VEGFR2 while not altering protein levels of angiostatic Hoxa5. Lungs returned to RA after 24 h 0.4FiO2 had partial structural recovery but remained smaller and less developed. Mesenchymal cell apoptosis increased and proliferation decreased with time in O2 while epithelial cell proliferation significantly increased. Hoxb5 overexpression led to prominent peri-airway VEGFR2 expression and promoted lung vascular and airway patterning. Hoxa5 overexpression had the opposite effects. We conclude that 0.4 FiO2 exposure causes a profound loss of airway and lung microvascular development that occurs partially via reduction in pro-angiogenic Hoxb5 while angiostatic Hoxa5 expression is maintained.

The adjuvant effect induced by di-(2-ethylhexyl) phthalate (DEHP) is mediated through oxidative stress in a mouse model of asthma

Di-(2-ethylhexyl) phthalate, as the most commonly used plasticizer, is considered to be related to the asthma prevalence. There are studies affirming that the DEHP has an adjuvant effect in the pathogenesis of allergy asthma. Oxidative stress is one possible pathway for DEHP-adjuvant effect. Thus, this study explored whether DEHP could induce adjuvant effect in mouse asthma model via oxidative stress pathway. Male BALB/c mice were randomly divided into six groups: (1) saline group, (2) DEHP group, (3) ovalbumin (OVA) group, (4) DEHP+OVA group, (5) OVA+vitamin E (Vit E) group, (6) DEHP+OVA+Vit E group. The exposure dose of DEHP was 30 mg/kg body weight (bw)/day. After 18 days of the exposure protocol. Reactive oxygen species (ROS), glutathione (GSH) and malonaldehyde (MDA) levels and biomarkers related to asthma model were measured. Collectively, these data indicated higher ROS and MDA levels and lower GSH contents in DEHP+OVA group than that in OVA group, while Vit E, an antioxidant, could restore ROS, MDA and GSH levels to control levels and attenuate the DEHP and/or OVA effects. Our observations suggested that there was a relationship between oxidative stress and the adjuvant effect induced by DEHP in this mouse asthma model.

The thioredoxin reductase-1 inhibitor aurothioglucose attenuates lung injury and improves survival in a murine model of acute respiratory distress syndrome

AIMS

Inflammation and oxygen toxicity increase free radical production and contribute to the development of acute respiratory distress syndrome (ARDS), which is a significant cause of morbidity and mortality in intensive care patients. We have previously reported increased glutathione (GSH) levels in lung epithelial cells in vitro and attenuated adult murine hyperoxic lung injury in vivo after pharmacological thioredoxin reductase-1 (TrxR1) inhibition. Using a murine ARDS model, we tested the hypothesis that aurothioglucose (ATG) treatment increases pulmonary GSH levels, attenuates lung injury, and decreases mortality in a GSH-dependent manner.

RESULTS

Adult mice received a single intratracheal dose of 0.375 μg/g lipopolysaccharide (LPS) 12 h before a single intraperitoneal injection of 25 mg/kg ATG. Control mice received intratracheal and/or intraperitoneal saline. Mice were then exposed to room air or hyperoxia (>95% O2). Lung injury was assessed by bronchoalveolar lavage protein concentrations. Expression of glutamate-cysteine ligase modifier subunit (GCLM), GSH, cytokines, and chemokines was determined. Exposure to LPS/hyperoxia induced inflammation and lung injury. ATG treatment significantly attenuated lung injury, increased lung GCLM expression and GSH levels, and decreased mortality. GSH depletion completely prevented the protective effects of ATG in LPS/hyperoxia-exposed mice.

INNOVATION

ATG treatment significantly attenuates lung injury and enhances survival in a clinically relevant murine model of ARDS. The protective effects of ATG are GSH dependent.

CONCLUSION

Augmentation of GSH systems by TrxR1 inhibition could represent a promising therapeutic approach to attenuate oxidant-mediated lung injury and improve patient outcomes.

The Ethanol Extract of Osmanthus fragrans Flowers Reduces Oxidative Stress and Allergic Airway Inflammation in an Animal Model

The Osmanthus fragrans flower, a popular herb in Eastern countries, contains several antioxidant compounds. Ben Cao Gang Mu, traditional Chinese medical literature, describes the usefulness of these flowers for phlegm and stasis reduction, arrest of dysentery with blood in the bowel, and stomachache and diarrhea treatment. However, modern evidence regarding the therapeutic efficacy of these flowers is limited. This study was aimed at assessing the antioxidative effects of the ethanol extract of O. fragrans flowers (OFE) in vivo and evaluating its antioxidant maintenance and therapeutic effect on an allergic airway inflammation in mice. After OFE's oral administration to mice, the values obtained in the oxygen radical absorbance capacity assay as well as the glutathione concentration in the lungs and spleens of mice increased while thiobarbituric acid reactive substances decreased significantly, indicating OFE's significant in vivo antioxidant activity. OFE was also therapeutically efficacious in a mouse model of ovalbumin-induced allergic airway inflammation. Orally administered OFE suppressed ovalbumin-specific IgE production and inflammatory cell infiltration in the lung. Moreover, the antioxidative state of the mice improved. Thus, our findings confirm the ability of the O. fragrans flowers to reduce phlegm and suggest that OFE may be useful as an antiallergic agent.

Nebulized and oral thiol derivatives for pulmonary disease in cystic fibrosis

BACKGROUND

Cystic fibrosis is an inherited condition resulting in thickened, sticky respiratory secretions. Respiratory failure, due to recurrent pulmonary infection and inflammation, is the most common cause of mortality. Muco-active therapies (e.g. dornase alfa and nebulized hypertonic saline) may decrease sputum viscosity, increase airway clearance of sputum, reduce infection and inflammation and improve lung function. Thiol derivatives, either oral or nebulized, have shown benefit in other respiratory diseases. Their mode of action is likely to differ according to the route of administration. There are several thiol derivatives, and it is unclear which of these may be beneficial in cystic fibrosis.

OBJECTIVES

To evaluate the efficacy and safety of nebulized and oral thiol derivatives in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches, hand searches of relevant journals, abstract books and conference proceedings.Most recent search: 13 June 2013.We also conducted a PubMed search on 26 February 2013 for relevant published articles.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing nebulized or oral thiol derivatives to placebo or another thiol derivative in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The authors independently assessed trials for inclusion, analysed risk of bias and extracted data.

MAIN RESULTS

Searches identified 23 trials; nine trials (255 participants) are included, of these seven trials are more than 10 years old. Three trials of nebulized thiol derivatives were identified (one compared 20% N-acetylcysteine to 2% N-acetylcysteine; another compared sodium-2-mercaptoethane sulphonate to 7% hypertonic saline; and another compared glutathione to 4% hypertonic saline). Although generally well-tolerated with no significant adverse effects, there was no evidence of significant clinical benefit in our primary outcomes in participants receiving these treatments.Six trials of oral thiol derivatives were identified. Three trials compared N-acetylcysteine to placebo; one compared N-acetylcysteine, ambroxol and placebo; one compared carbocysteine to ambroxol; and one compared low and high-dose N-acetylcysteine. Oral thiol derivatives were generally well-tolerated with no significant adverse effects, however there was no evidence of significant clinical benefit in our primary outcomes in participants receiving these treatments.

AUTHORS' CONCLUSIONS

We found no evidence to recommend the use of either nebulized or oral thiol derivatives in people with cystic fibrosis. There are very few good quality trials investigating the effect of these medications in cystic fibrosis, and further research is required to investigate the potential role of these medications in improving the outcomes of people with cystic fibrosis.

Grape seed proanthocyanidin extract attenuates allergic inflammation in murine models of asthma

BACKGROUND

Antioxidants have been suggested to alleviate the pathophysiological features of asthma, and grape seed proanthocyanidin extract (GSPE) has been reported to have powerful antioxidant activity.

PURPOSE

This study was performed to determine whether GSPE has a therapeutic effect on allergic airway inflammation in both acute and chronic murine model of asthma.

METHODS

Acute asthma model was generated by intraperitoneal sensitization of ovalbumin (OVA) with alum followed by aerosolized OVA challenges, whereas chronic asthma model was induced by repeated intranasal challenges of OVA with fungal protease twice a week for 8 weeks. GSPE was administered by either intraperitoneal injection or oral gavage before OVA challenges. Airway hyperresponsiveness (AHR) was measured, and airway inflammation was evaluated by bronchoalveolar lavage (BAL) fluid analysis and histopathological examination of lung tissue. Lung tissue levels of various cytokines, chemokines, and growth factors were analyzed by quantitative polymerase chain reaction and ELISA. Glutathione assay was done to measure oxidative burden in lung tissue.

RESULTS

Compared to untreated asthmatic mice, mice treated with GSPE showed significantly reduced AHR, decreased inflammatory cells in the BAL fluid, reduced lung inflammation, and decreased IL-4, IL-5, IL-13, and eotaxin-1 expression in both acute and chronic asthma models. Moreover, airway subepithelial fibrosis was reduced in the lung tissue of GSPE-treated chronic asthmatic mice compared to untreated asthmatic mice. Reduced to oxidized glutathione (GSH/GSSG) ratio was increased after GSPE treatment in acute asthmatic lung tissue.

CONCLUSION

GSPE effectively suppressed inflammation in both acute and chronic mouse models of asthma, suggesting a potential role of GSPE as a therapeutic agent for asthma.

Oxidative stress-induced biomarkers for stem cell-based chemical screening

Stem cells have been considered for their potential in pharmaceutical research, as well as for stem cell-based therapy for many diseases. Despite the potential for their use, the challenge remains to examine the safety and efficacy of stem cells for their use in therapies. Recently, oxidative stress has been strongly implicated in the functional regulation of cell behavior of stem cells. Therefore, development of rapid and sensitive biomarkers, related to oxidative stress is of growing importance in stem cell-based therapies for treating various diseases. Since stem cells have been implicated as targets for carcinogenesis and might be the origin of "cancer stem cells", understanding of how oxidative stress-induced signaling, known to be involved in the carcinogenic process could lead to potential screening of cancer chemopreventive and chemotherapeutic agents. An evaluation of antioxidant states reducing equivalents like GSH and superoxide dismutase (SOD), as well as reactive oxygen species (ROS) and nitric oxide (NO) generation, can be effective markers in stem cell-based therapies. In addition, oxidative adducts, such as 4-hydroxynonenal, can be reliable markers to detect cellular changes during self-renewal and differentiation of stem cells. This review highlights the biomarker development to monitor oxidative stress response for stem cell-based chemical screening.

Interaction with CREB binding protein modulates the activities of Nrf2 and NF-κB in cystic fibrosis airway epithelial cells

Cystic fibrosis (CF) is characterized by inflammatory lung disease that significantly contributes to morbidity and mortality. Airway epithelial cells play a role in the inflammatory signaling in CF and have been reported to exhibit a number of dysfunctions in signaling cascades that modulate inflammation. Previously, we reported that the activity of nuclear factor erythroid-derived-like 2 (Nrf2), a transcription factor that regulates antioxidant and cytoprotective protein expression, is diminished in CF epithelia (7). In this report, we examined the mechanism of Nrf2 dysregulation in vitro in human airway epithelial cell lines and primary cells and in vivo in nasal epithelia excised from ΔF508 CF mutant mice. We found that cAMP-mediated signaling markedly reduces Nrf2 activity in CF vs. non-CF cells. Rp-cAMPS, a cAMP competitor, significantly corrected Nrf2 activity in CF cells, predominantly by increasing the nuclear accumulation of the transcription factor. Furthermore, we found that Rp-cAMPS significantly decreased NF-κB activation following inflammatory stimulation of CF cells. Further investigation revealed that Nrf2 and NF-κB compete for the transcriptional coactivator cAMP responsive element-binding protein (CREB) binding protein (CBP) and that Rp-cAMPS shifts CBP association in favor of Nrf2. Thus our findings provide a link between feedback to CF transmembrane regulator dysfunction and dysregulation of an inflammatory signaling pathway that modulates the coordinated activities of Nrf2 and NF-κB. Furthermore, our studies suggest that strategies that shift CBP association away from NF-κB and toward Nrf2 could have potential therapeutic efficacy for reducing inflammation in patients with CF.

A computable cellular stress network model for non-diseased pulmonary and cardiovascular tissue

Background

Humans and other organisms are equipped with a set of responses that can prevent damage from exposure to a multitude of endogenous and environmental stressors. If these stress responses are overwhelmed, this can result in pathogenesis of diseases, which is reflected by an increased development of, e.g., pulmonary and cardiac diseases in humans exposed to chronic levels of environmental stress, including inhaled cigarette smoke (CS). Systems biology data sets (e.g., transcriptomics, phosphoproteomics, metabolomics) could enable comprehensive investigation of the biological impact of these stressors. However, detailed mechanistic networks are needed to determine which specific pathways are activated in response to different stressors and to drive the qualitative and eventually quantitative assessment of these data. A current limiting step in this process is the availability of detailed mechanistic networks that can be used as an analytical substrate.

Results

We have built a detailed network model that captures the biology underlying the physiological cellular response to endogenous and exogenous stressors in non-diseased mammalian pulmonary and cardiovascular cells. The contents of the network model reflect several diverse areas of signaling, including oxidative stress, hypoxia, shear stress, endoplasmic reticulum stress, and xenobiotic stress, that are elicited in response to common pulmonary and cardiovascular stressors. We then tested the ability of the network model to identify the mechanisms that are activated in response to CS, a broad inducer of cellular stress. Using transcriptomic data from the lungs of mice exposed to CS, the network model identified a robust increase in the oxidative stress response, largely mediated by the anti-oxidant NRF2 pathways, consistent with previous reports on the impact of CS exposure in the mammalian lung.

Conclusions

The results presented here describe the construction of a cellular stress network model and its application towards the analysis of environmental stress using transcriptomic data. The proof-of-principle analysis described here, coupled with the future development of additional network models covering distinct areas of biology, will help to further clarify the integrated biological responses elicited by complex environmental stressors such as CS, in pulmonary and cardiovascular cells.

Hydrogen peroxide in exhaled breath condensate in patients with asthma: a promising biomarker?

BACKGROUND

The measurement of hydrogen peroxide (H(2)O(2)) in exhaled breath condensate (EBC) has been proposed as a noninvasive way of monitoring airway inflammation. However, results from individual studies on EBC H(2)O(2) evaluation of asthma are conflicting. The purpose of this study was to explore whether EBC H(2)O(2) is elevated in people with asthma and whether it reflects disease severity and disease control or responds to corticosteroid treatment.

METHODS

Studies were identified by searching PubMed, Embase, Cochrane Database, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and www.controlled-trials.com for relevant reports published before September 2010. Observational studies comparing levels of EBC H(2)O(2) between patients with asthma who were nonsmokers and healthy subjects were included. Data were independently extracted by two investigators and analyzed using Stata 10.0 software.

RESULTS

Eight studies (involving 728 participants) were included. EBC H(2)O(2) concentrations were significantly higher in patients with asthma who were nonsmokers compared with healthy subjects, and higher values of EBC H(2)O(2) were observed at each level of asthma, classified either by severity or control level, and the values were negatively correlated with FEV(1). In addition, EBC H(2)O(2) concentrations were lower in patients with asthma treated with corticosteroids than in patients with asthma not treated with corticosteroids.

CONCLUSIONS

H(2)O(2) might be a promising biomarker for guiding asthma treatment. However, further investigation is needed to establish its role.

Glutathione oxidation is associated with airway macrophage functional impairment in children with severe asthma

Airway cellular dysfunction is a differentiating feature of severe asthma in children that may be related to an imbalance of the antioxidant, glutathione (GSH). We hypothesized that oxidation of GSH to glutathione disulfide (GSSG) in the epithelial lining fluid (ELF) of children with severe asthma would contribute to altered airway macrophage (AM) GSH homeostasis and AM cellular dysfunction. Bronchoalveolar lavage (BAL) was performed in 64 asthmatic children (severe asthma, n = 43). GSH, GSSG, markers of lipid peroxidation and DNA oxidation, and IL-8 were quantified in the BAL supernatant. GSH, GSSG, activities of histone deacetylase (HDAC) and histone acetyltransferase, apoptosis, and phagocytosis were assessed in isolated AMs. Children with severe asthma had increased GSSG, lipid peroxidation, byproducts of DNA oxidation, and inflammation in the ELF. This imbalance of GSH homeostasis was also noted intracellularly within the AMs and was associated with decreased HDAC activities, increased apoptosis, and impaired phagocytosis. In vitro GSH supplementation inhibited apoptosis and rescued phagocytosis in children with severe asthma. Severe asthma in children is characterized by altered airway and intracellular AM GSH homeostasis that translates to impaired AM function. Interventions to restore airway GSH homeostasis may be warranted in children with severe asthma.

Tumor necrosis factor expression is ameliorated after exposure to an acidic environment

BACKGROUND

It has been well established that laparoscopic surgery presents several clinical benefits, including reduced pain and a shorter hospital stay. These effects have been associated with a decrease in the inflammatory response. Previous studies have demonstrated that reduced inflammation after laparoscopic surgery is the product of carbon dioxide insufflation, which decreases peritoneal pH. The objective of this study was to investigate the cellular and molecular mechanisms responsible for the reduced response after exposure to acidic environments.

MATERIALS AND METHODS

A murine macrophage line (J744) was incubated in culture medium at pH 6.0 or pH 7.4 for 3 h at 37°C. Then, cells were stimulated with lipopolysaccharide (LPS) at pH 7.4, the expression of TNF-α (qRT-PCR or enzyme-linked immunosorbent assay (ELISA) and intracellular pH were measured. In addition, CD14 and Toll-like receptor 4 expression and NF-κB nuclear translocation were analyzed.

RESULTS

A significant decrease in LPS-induced TNF-α expression levels was observed in cells pre-incubated at pH 6.0 in comparison with cells at neutral pH conditions. This decrease in TNF-α levels was not associated with a reduction in cell surface expression of CD14 and Toll-like receptor 4. Exposure to an extracellular acidic environment resulted in a reduction of IκB phosphorylation and NF-κB nuclear translocation, secondary to a significant drop in cytosolic pH.

CONCLUSIONS

These observations provide a potential mechanism for the reduced expression of TNF-α after exposure to low extracellular pH, which may be related to acidification after CO(2) insufflation during laparoscopic surgery. In addition, extracellular acidic pH environments could emerge as an important regulator of macrophage function.

Epithelial-mesenchymal transition: from molecular mechanisms, redox regulation to implications in human health and disease

Epithelial to mesenchymal transition (EMT) is a fundamental process, paradigmatic of the concept of cell plasticity, that leads epithelial cells to lose their polarization and specialized junctional structures, to undergo cytoskeleton reorganization, and to acquire morphological and functional features of mesenchymal-like cells. Although EMT has been originally described in embryonic development, where cell migration and tissue remodeling have a primary role in regulating morphogenesis in multicellular organisms, recent literature has provided evidence suggesting that the EMT process is a more general biological process that is also involved in several pathophysiological conditions, including cancer progression and organ fibrosis. This review offers first a comprehensive introduction to describe major relevant features of EMT, followed by sections dedicated on those signaling mechanisms that are known to regulate or affect the process, including the recently proposed role for oxidative stress and reactive oxygen species (ROS). Current literature data involving EMT in both physiological conditions (i.e., embryogenesis) and major human diseases are then critically analyzed, with a special final focus on the emerging role of hypoxia as a relevant independent condition able to trigger EMT.

The role of oxidative stress in the pathogenesis of asthma

Oxidative stress plays a critical role in the pathogenesis of asthma. To effectively control oxidative stress in asthmatics, it is important to investigate the precise intracellular mechanism by which the development of immunity, rather than immune tolerance and progression of airway inflammation, is induced. In this article, we suggest that protein tyrosine phosphatases, as intracellular negative regulators, and intracellular antioxidant enzymes such as peroxiredoxins can be regulated by oxidative stress during intracellular signaling.

Glutathione deficient C57BL/6J mice are not sensitized to ozone-induced lung injury

In this study we examined the role of the antioxidant glutathione (GSH) in pulmonary susceptibility to ozone toxicity, utilizing GSH deficient C57BL/6J mice that lack the expression of glutamate-cysteine ligase modifier subunit (GCLM). Gclm(-/-) knockout mice had 70% GSH depletion in the lung. Gclm(+/+) wild-type and Gclm(-/-) mice were exposed to either 0.3 ppm ozone or filtered air for 48h. Ozone-induced lung hyperpermeability, as measured by total protein concentration in bronchoalveolar lavage fluid, was surprisingly lower in Gclm(-/-) mice than in wild-type mice. Lung hyperpermeability did not correlate with the degree of neutrophilia or with inflammatory gene expression. Pulmonary antioxidant response to ozone, assessed by increased mRNA levels of metallothionein 1 and 2, alpha-tocopherol transporter protein, and solute carrier family 23 member 2 (sodium-dependent vitamin C transporter) was greater in Gclm(-/-) mice than in Gclm(+/+) mice. These results suggest that compensatory augmentation of antioxidant defenses in Gclm(-/-) mice may confer increased resistance to ozone-induced lung injury.

Roles of oxidative stress in signaling and inflammation induced by particulate matter

This review reports the role of oxidative stress in impairing the function of lung exposed to particulate matter (PM). PM constitutes a heterogeneous mixture of various types of particles, many of which are likely to be involved in oxidative stress induction and respiratory diseases. Probably, the ability of PM to cause oxidative stress underlies the association between increased exposure to PM and exacerbations of lung disease. Mostly because of their large surface area, ultrafine particles have been shown to cause oxidative stress and proinflammatory effects in different in vivo and in vitro studies. Particle components and surface area may act synergistically inducing lung inflammation. In this vein, reactive oxygen species elicited upon PM exposure have been shown to activate a number of redox-responsive signaling pathways and Ca(2+) influx in lung target cells that are involved in the expression of genes that modulate relevant responses to lung inflammation and disease.

Dosimetry and toxicology of inhaled ultrafine particles

Both epidemiological and toxicological studies indicate that inhalation and subsequent deposition of airborne particles into the lungs have adverse health effects. Recently, the ultrafine particle (UfP) fraction (diameter < 100 nm) has received particular attention, as their small size may lead to more toxic properties. In this study we summarize the current knowledge on the dosimetry of inhaled particles (including UfPs) with a focus on recent data on translocation of UfPs into secondary target organs (such as brain and heart) suggesting that the lifetime dose of ambient UfPs in secondary target organs is about 10(11) particles. Furthermore, we highlight the main pathways of particle induced toxicity and the reasons for the potentially higher toxicity of UfPs. Finally, we discuss recent evidence indicating that (BET) surface area is the single most relevant dose metric for the toxicity of UfPs, which has important implications for regulatory measures on the toxicity of ambient and engineered particles.

Redox control of the cell cycle in health and disease

The cellular oxidation and reduction (redox) environment is influenced by the production and removal of reactive oxygen species (ROS). In recent years, several reports support the hypothesis that cellular ROS levels could function as ''second messengers'' regulating numerous cellular processes, including proliferation. Periodic oscillations in the cellular redox environment, a redox cycle, regulate cell-cycle progression from quiescence (G(0)) to proliferation (G(1), S, G(2), and M) and back to quiescence. A loss in the redox control of the cell cycle could lead to aberrant proliferation, a hallmark of various human pathologies. This review discusses the literature that supports the concept of a redox cycle controlling the mammalian cell cycle, with an emphasis on how this control relates to proliferative disorders including cancer, wound healing, fibrosis, cardiovascular diseases, diabetes, and neurodegenerative diseases. We hypothesize that reestablishing the redox control of the cell cycle by manipulating the cellular redox environment could improve many aspects of the proliferative disorders.

Increased oxidative stress in the airway and development of allergic inflammation in a mouse model of asthma

BACKGROUND

The exact pathogenic role of oxidative stress in the development of allergic airway inflammation is still largely unknown.

OBJECTIVE

To investigate a possible link between increased pulmonary oxidative stress and the pivotal features of asthma during the mounting of an allergic inflammatory response.

METHODS

To determine the relationship between oxidative stress and allergic inflammatory responses, we evaluated the sequential kinetics of oxidative stress in the lung, the development of airway inflammation, mucin hypersecretion, and airway hyperresponsiveness (AHR) in an ovalbumin (OVA)-sensitized and challenged mouse with and without antioxidant. Parameters were measured at 9 points for more than 28 days, starting from the first day of OVA challenge with or without antioxidant treatment. The ratio of reduced to oxidized glutathione in the lungs and levels of intracellular reactive oxygen species (ROS) in the bronchial epithelium were serially measured. Bronchoalveolar lavage fluid cells, histopathologic features, and AHR were analyzed at the same time points.

RESULTS

The reduced to oxidized glutathione ratio was reduced from immediately after OVA challenge to day 1, remained at this level until day 1, and rapidly recovered to the normal level after more than 2 days. Intracellular ROS levels in the bronchial epithelium followed similar kinetics. The inflammatory cells in bronchoalveolar lavage fluid reached a maximum of 3 days and decreased progressively thereafter. Histopathologic examination revealed that substantial airway inflammation persisted through day 28. The proportion of mucin-producing epithelial cells significantly increased after day 1, reached a maximum at day 3, and remained at this level until day 5. The AHR peaked on day 1 and normalized within 5 days. The pretreatment of antioxidant significantly reduced not only the increased ROS levels but also development of other phenotypes of asthma.

CONCLUSION

These results indicate that increased oxidative stress in the lung precedes other pivotal phenotypes of allergic airway disease, suggesting a critical role for increased oxidative stress in the induction of allergic airway inflammation.

Simultaneous detection of cysteine sulfenate, sulfinate, and sulfonate during cysteine interfacial ozonolysis

Sulfenic acids (RSOH) are reactive intermediates in the oxidation of protein cysteines. Among cysteine oxoforms, RSOH represent redox-reversible species that can thus participate in regulation and signaling mechanisms and play key roles in enzyme catalysis and antioxidant activity. How the cysteine (CyS) thiol groups of the human surfactant protein that lines the lung epithelium react with inhaled ozone is deemed critical in preserving structural integrity and immune functions. Here we report the simultaneous detection, by online thermospray ionization mass spectrometry, of cysteine sulfenate (CySO(-)) and the overoxidized cysteine sulfinate (CySO(2)(-)) and cysteine sulfonate (CySO(3)(-)) species on the surface of aqueous CyS microdroplets exposed to O(3)(g) for <1 ms. These species are produced by rapid, sequential O-atom additions whose relative rates are herein quantified for the first time. From the pH-dependence of ozonation rates, we derive pK(a)(CySOH) = 7.6 +/- 0.3 < pK(a)(CyS) = 8.3.

How phenol and alpha-tocopherol react with ambient ozone at gas/liquid interfaces

The exceptional ability of alpha-tocopherol (alpha-TOH) for scavenging free radicals is believed to also underlie its protective functions in respiratory epithelia. Phenols, however, can scavenge other reactive species. Herein, we report that alpha-TOH/alpha-TO(-) reacts with closed-shell O(3)(g) on the surface of inert solvent microdroplets in < 1 ms to produce persistent alpha-TO-O(n)(-)(n = 1-4) adducts detectable by online thermospray ionization mass spectrometry. The prototype phenolate PhO(-), in contrast, undergoes electron transfer under identical conditions. These reactions are deemed to occur at the gas/liquid interface because their rates: (1) depend on pH, (2) are several orders of magnitude faster than within microdroplets saturated with O(3)(g). They also fail to incorporate solvent into the products: the same alpha-TO-O(n)(-) species are formed on acetonitrile or nucleophilic methanol microdroplets. alpha-TO-O(n = 1-3)(-) signals initially evolve with [O(3)(g)] as expected from first-generation species, but alpha-TO-O(-) reacts further with O(3)(g) and undergoes collisionally induced dissociation into a C(19)H(40) fragment (vs C(19)H(38) from alpha-TO(-)) carrying the phytyl side chain, whereas the higher alpha-TO-O(n > or = 2)(-) homologues are unreactive toward O(3)(g) and split CO(2) instead. On this basis, alpha-TO-O(-) is assigned to a chroman-6-ol (4a, 8a)-ene oxide, alpha-TO-O(2)(-) to an endoperoxide, and alpha-TO-O(3)(-) to a secondary ozonide. The atmospheric degradation of the substituted phenols detected in combustion emissions is therefore expected to produce related oxidants on the aerosol particles present in the air we breathe.

The wanderings of a free radical

In my career I have moved from chemistry to biochemistry to plant science to clinical chemistry and back again (in a partial way) to plants. This review presents a brief history of my research achievements (ascorbate-glutathione cycle, role of iron in oxidative damage and human disease, biomarkers of free radical damage, and studies on atherosclerosis and neurodegeneration) and how they relate to my research activities today. The field of free radicals/other reactive species/antioxidants underpins all of modern Biology. These agents helped to drive human evolution and the basic principles of the field are repeatedly found to be relevant in other research areas. It was an exciting field when I started some 40 years ago, and it still is today, but some major challenges must be faced.

HIV-1 transgene expression in rats causes oxidant stress and alveolar epithelial barrier dysfunction

Background

HIV-infected individuals are at increased risk for acute and chronic airway disease even though there is no evidence that the virus can infect the lung epithelium. Although HIV-related proteins including gp120 and Tat can directly cause oxidant stress and cellular dysfunction, their effects in the lung are unknown. The goal of this study was to determine the effects of HIV-1 transgene expression in rats on alveolar epithelial barrier function. Alveolar epithelial barrier function was assessed by determining lung liquid clearance in vivo and alveolar epithelial monolayer permeability in vitro. Oxidant stress in the alveolar space was determined by measuring the glutathione redox couple by high performance liquid chromatography, and the expression and membrane localization of key tight junction proteins were assessed. Finally, the direct effects of the HIV-related proteins gp120 and Tat on alveolar epithelial barrier formation and tight junction protein expression were determined.

Results

HIV-1 transgene expression caused oxidant stress within the alveolar space and impaired epithelial barrier function even though there was no evidence of overt inflammation within the airways. The expression and membrane localization of the tight junction proteins zonula occludens-1 and occludin were decreased in alveolar epithelial cells from HIV-1 transgenic rats. Further, treating alveolar epithelial monolayers from wild type rats in vitro with recombinant gp120 or Tat for 24 hours reproduced many of the effects on zonula occludens-1 and occludin expression and membrane localization.

Conclusion

Taken together, these data indicate that HIV-related proteins cause oxidant stress and alter the expression of critical tight junction proteins in the alveolar epithelium, resulting in barrier dysfunction.

Nebulized and oral thiol derivatives for pulmonary disease in cystic fibrosis

BACKGROUND

Cystic fibrosis is an inherited condition resulting in thickened, sticky respiratory secretions. Respiratory failure, due to recurrent pulmonary infection and inflammation, is the most common cause of mortality. Muco-active therapies (e.g. dornase alfa and nebulized hypertonic saline) may decrease sputum viscosity, increase airway clearance of sputum, reduce infection and inflammation and improve lung function. Thiol derivatives, either oral or nebulized, have shown benefit in other respiratory diseases. Their mode of action is likely to differ according to the route of administration. There are several thiol derivatives, and it is unclear which of these may be beneficial in cystic fibrosis.

OBJECTIVES

To evaluate the efficacy and safety of nebulized and oral thiol derivatives in people with cystic fibrosis.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches, hand searches of relevant journals, abstract books and conference proceedings.Most recent search: November 2008.

SELECTION CRITERIA

Randomized and quasi-randomized controlled trials comparing nebulized or oral thiol derivatives to placebo or another thiol derivative in people with cystic fibrosis.

DATA COLLECTION AND ANALYSIS

The authors independently assessed trials for inclusion, analysed methodological quality and extracted data.

MAIN RESULTS

Searches identified 18 trials; eight (seven older than 10 years) (234 participants) are included. Three trials of nebulized thiol derivatives were identified (one compared 20% n-acetylcysteine to 2% n-acetylcysteine; another compared sodium-2-mercaptoethane sulphonate to 7% hypertonic saline; and another compared glutathione to 4% hypertonic saline). Although generally well-tolerated with no significant adverse effects, there was no evidence of significant clinical benefit in our primary outcomes in participants receiving these treatments.Five studies of oral thiol derivatives were identified. Three studies compared n-acetylcysteine to placebo; one compared n-acetylcysteine, ambroxol and placebo; and one compared carbocysteine to ambroxol. Oral thiol derivatives were generally well-tolerated with no significant adverse effects, however there was no evidence of significant clinical benefit in our primary outcomes in participants receiving these treatments.

AUTHORS' CONCLUSIONS

We found no evidence to recommend the use of either nebulized or oral thiol derivatives in people with cystic fibrosis. There are very few good quality trials investigating the effect of these medications in cystic fibrosis, and further research is required to investigate the potential role of these medications in improving the outcomes of people with cystic fibrosis.

Deducing in vivo toxicity of combustion-derived nanoparticles from a cell-free oxidative potency assay and metabolic activation of organic compounds

BACKGROUND

The inhalation of combustion-derived nanoparticles (CDNPs) is believed to cause an oxidative stress response, which in turn may lead to pulmonary or even systemic inflammation.

OBJECTIVE AND METHODS

In this study we assessed whether the in vivo inflammatory response--which is generally referred to as particle toxicity-of mice to CDNPs can be predicted in vitro by a cell-free ascorbate test for the surface reactivity or, more precisely, oxidative potency (OxPot) of particles.

RESULTS

For six types of CDNPs with widely varying particle diameter (10-50 nm), organic content (OC; 1-20%), and specific Brunauer, Emmett, and Teller (BET) surface area (43-800 m2/g), OxPot correlated strongly with the in vivo inflammatory response (pulmonary polymorphonuclear neutrophil influx 24 hr after intratracheal particle instillation). However, for CDNPs with high organic content, OxPot could not explain the observed inflammatory response, possibly due to shielding of the OxPot of the carbon core of CDNPs by an organic coating. On the other hand, a pathway-specific gene expression screen indicated that, for particles rich in polycyclic aromatic hydrocarbon (PAHs), cytochrome P450 1A1 (CYP1A1) enzyme-mediated biotransformation of bio-available organics may generate oxidative stress and thus enhance the in vivo inflammatory response.

CONCLUSION

The compensatory nature of both effects (shielding of carbon core and biotransformation of PAHs) results in a good correlation between inflammatory response and BET surface area for all CDNPs. Hence, the in vivo inflammatory response can either be predicted by BET surface area or by a simple quantitative model, based on in vitro OxPot and Cyp1a1 induction.

Redox mechanisms in hepatic chronic wound healing and fibrogenesis

Reactive oxygen species (ROS) generated within cells or, more generally, in a tissue environment, may easily turn into a source of cell and tissue injury. Aerobic organisms have developed evolutionarily conserved mechanisms and strategies to carefully control the generation of ROS and other oxidative stress-related radical or non-radical reactive intermediates (that is, to maintain redox homeostasis), as well as to 'make use' of these molecules under physiological conditions as tools to modulate signal transduction, gene expression and cellular functional responses (that is, redox signalling). However, a derangement in redox homeostasis, resulting in sustained levels of oxidative stress and related mediators, can play a significant role in the pathogenesis of major human diseases characterized by chronic inflammation, chronic activation of wound healing and tissue fibrogenesis. This review has been designed to first offer a critical introduction to current knowledge in the field of redox research in order to introduce readers to the complexity of redox signalling and redox homeostasis. This will include ready-to-use key information and concepts on ROS, free radicals and oxidative stress-related reactive intermediates and reactions, sources of ROS in mammalian cells and tissues, antioxidant defences, redox sensors and, more generally, the major principles of redox signalling and redox-dependent transcriptional regulation of mammalian cells. This information will serve as a basis of knowledge to introduce the role of ROS and other oxidative stress-related intermediates in contributing to essential events, such as the induction of cell death, the perpetuation of chronic inflammatory responses, fibrogenesis and much more, with a major focus on hepatic chronic wound healing and liver fibrogenesis.

Cytoprotective roles of senescence marker protein 30 against intracellular calcium elevation and oxidative stress

Senescence marker protein 30 (SMP30) is identified as an important aging marker molecule and known to play multifunctional roles as an intracellular calcium regulatory protein in the signaling process. To elucidate the functional significance of SMP30, we established the stably transfected P19 cell line with SMP30 expression vector. Overexpression of SMP30 slightly suppressed the proliferation of P19 cells. However, SMP30 overexpression was cytoprotective against calcium-mediated stress such as calcium ionophore (A23187), and thapsigargin. We found that SMP30 overexpression reduced the elevated intracellular calcium levels induced by A23187, but not by thapsigargin. In addition, SMP30 transfected P19 cells were more protective to tert-butylhydroperoxide induced cytotoxicity, indicating the antioxidative properties of SMP30. Taken together, our results suggest that external calcium regulation and antioxidant properties are involved in the cytoprotective mechanism of SMP30.

PMX464, a thiol-reactive quinol and putative thioredoxin inhibitor, inhibits NF-kappaB-dependent proinflammatory activation of alveolar epithelial cells

BACKGROUND AND PURPOSE

Subtle changes in the intracellular reduction-oxidation (redox) state can modulate nuclear factor-kappaB (NF-kappaB) activity. Thioredoxin-1 (Trx) is a small, ubiquitous, redox-active thiol (-SH) protein that, with thioredoxin reductase-1 (TrxR), modifies the redox status of NF-kappaB pathway components. PMX464 is a novel thiol-reactive quinol thought to inhibit the Trx/TrxR system. The aim of this work was to investigate whether PMX464 inhibited NF-kappaB-mediated proinflammatory activation of human type II alveolar epithelial cells (A549).

EXPERIMENTAL APPROACH

Intercellular adhesion molecule-1 (ICAM-1), granulocyte-macrophage colony-stimulating factor (GM-CSF) and CXCL8, NF-kappaB DNA binding, nuclear translocation of NF-kappaB p65 subunit, IkappaBalpha degradation, IkappaB phosphorylation and IkappaB kinase (IKK) activity were assessed in A549 cells stimulated with IL-1beta with or without PMX464 pretreatment. Effects of PMX464 on ICAM-1 expression in human lung microvascular endothelial cells (HLMVEC) were also investigated. For comparison, selected measurements (ICAM-1 and IkappaB-alpha phospho-IkappaB-alpha) were made on A549 cells after RNA interference-mediated silencing (siRNA) of Trx.

KEY RESULTS

PMX464 reduced ICAM-1, GM-CSF and CXCL8 expression in IL-1beta-stimulated A549 cells and ICAM-1 in HLMVEC. PMX464 inhibited IL-1beta-induced NF-kappaB DNA binding, nuclear translocation of NF-kappaB p65 subunit and factors involved in NF-kappaB activation; specifically, IkappaBalpha degradation, IkappaB phosphorylation and IkappaB kinase (IKK) activity in A549. By contrast, Trx siRNA did not alter ICAM-1 expression or IkappaBalpha degradation/phosphorylation in IL-1beta-stimulated A549 cells.

CONCLUSION AND IMPLICATIONS

PMX464 inhibits a proinflammatory response in A549 cells targeting the NFkappaB pathway above IKK. The lack of effect with Trx siRNA suggests that PMX464 acts on thiol proteins, in addition to Trx, to elicit anti-inflammatory responses in lung epithelial cells.

Relative contributions of TRPA1 and TRPV1 channels in the activation of vagal bronchopulmonary C-fibres by the endogenous autacoid 4-oxononenal

Transient receptor potential (TRP) A1 channels are cation channels found preferentially on nociceptive sensory neurones, including capsaicin-sensitive TRPV1-expressing vagal bronchopulmonary C-fibres, and are activated by electrophilic compounds such as mustard oil and cinnamaldehyde. Oxidative stress, a pathological feature of many respiratory diseases, causes the endogenous formation of a number of reactive electrophilic alkenals via lipid peroxidation. One such alkenal, 4-hydroxynonenal (4HNE), activates TRPA1 in cultured sensory neurones. However, our data demonstrate that 100 microm 4HNE was unable to evoke significant action potential discharge or tachykinin release from bronchopulmonary C-fibre terminals. Instead, another endogenously produced alkenal, 4-oxononenal (4ONE, 10 microm), which is far more electrophilic than 4HNE, caused substantial action potential discharge and tachykinin release from bronchopulmonary C-fibre terminals. The activation of mouse bronchopulmonary C-fibre terminals by 4ONE (10-100 microm) was mediated entirely by TRPA1 channels, based on the absence of responses in C-fibre terminals from TRPA1 knockout mice. Interestingly, although the robust increases in calcium caused by 4ONE (0.1-10 microm) in dissociated vagal neurones were essentially abolished in TRPA1 knockout mice, at 100 microm 4ONE caused a large TRPV1-dependent response. Furthermore, 4ONE (100 microm) was shown to activate TRPV1 channel-expressing HEK cells. In conclusion, the data support the hypothesis that 4-ONE is a relevant endogenous activator of vagal C-fibres via an interaction with TRPA1, and at less relevant concentrations, it may activate nerves via TRPV1.

Tyrosine phosphatase SHP-1 in oxidative stress and development of allergic airway inflammation

Oxidative stress has been implicated in allergic responses. SHP-1 is a target of oxidants and has been reported as a negative regulator in a mouse model of asthma. We investigated the effect of oxidative stress on the development of allergic airway inflammation in heterozygous viable motheaten (mev/+) mice deficient of SHP-1. Wild-type (WT) and mev/+ mice were compared in this study. Human alveolar epithelial cells (A549) transfected with mutant SHP-1 gene were used to evaluate the role of SHP-1 in lung epithelial cells. Hydrogen peroxide (H(2)O(2)) and Paraquat were used in vitro and in vivo, respectively. We also investigated whether mev/+ mice can break immune tolerance when exposed to aeroallergen intranasally. Compared with WT mice, bronchoalveolar lavage (BAL) cells and splenocytes from mev/+ mice showed a different response to oxidant stress. This includes a significant enhancement of intracellular reactive oxygen species and STAT6 phosphorylation in vitro and increased CCL20, decreased IL-10, and increased number of dendritic cells in BAL fluid in vivo. Mutant SHP-1-transfected epithelial cells secreted higher levels of CCL20 and RANTES after exposure to oxidative stress. Furthermore, break of immune tolerance, as development of allergic airway inflammation, was observed in mev/+ mice after allergen exposure, which was suppressed by antioxidant N-acetylcystein. These data suggest that SHP-1 plays an important role in regulating oxidative stress. Thus, increased intracellular oxidative stress and lack of SHP-1 in the presence of T helper cell type 2-prone cellular activation may lead to the development of allergic airway inflammation.

Transforming growth factor-beta activation in the lung: focus on fibrosis and reactive oxygen species

Transforming growth factor-betas (TGF-beta) regulate a wide variety of cellular functions in normal development and are involved in both tissue homeostasis and disease pathogenesis. The regulation of the TGF-beta family of growth factors is unique because they are targeted to the extracellular matrix in a biologically inactive form. The release from pericellular matrices and the activation of TGF-beta are important mechanisms in several pathophysiologic conditions. Reactive oxygen species (ROS) can activate TGF-beta either directly or indirectly via the activation of proteases. In addition, TGF-beta itself induces ROS production as part of its signal-transduction pathway. The lung is a unique organ, because its structures act as boundaries between gaseous and aqueous phases, allowing the utilization of inhaled oxygen. However, this renders pulmonary tissues vulnerable to the toxic effects of inhaled air. The oxidant pathways are especially relevant in the lung, where TGF-beta is known to have a role in tissue repair and connective tissue turnover. In pulmonary fibrosis, TGF-beta activation is considered as a hallmark of disease progression. More recently, the oxidative effects of cigarette smoking have been found to activate TGF-beta in chronic obstructive pulmonary disease (COPD), a disease consisting of emphysema, airway fibrosis, and focal lung fibrosis.