Oxidant--antioxidant imbalance in asthma: scientific evidence, epidemiological data and possible therapeutic options

β-Endorphin (an endogenous opioid) inhibits inflammation, oxidative stress and apoptosis via Nrf-2 in asthmatic murine model

Asthma, a chronic respiratory disease is characterized by airway inflammation, remodelling, airflow limitation and hyperresponsiveness. At present, it is considered as an umbrella diagnosis consisting several variable clinical presentations (phenotypes) and distinct pathophysiological mechanisms (endotypes). Recent evidence suggests that oxidative stress participates in airway inflammation and remodelling in chronic asthma. Opioids resembled by group of regulatory peptides have proven to act as an immunomodulator. β-Endorphin a natural and potent endogenous morphine produced in the anterior pituitary gland play role in pain modulation. Therapeutic strategy of many opioids including β-Endorphin as an anti‑inflammatory and antioxidative agent has not been yet explored despite its promising analgesic effects. This is the first study to reveal the role of β-Endorphin in regulating airway inflammation, cellular apoptosis, and oxidative stress via Nrf-2 in an experimental asthmatic model. Asthma was generated in balb/c mice by sensitizing with 1% Toulene Diisocyanate on day 0, 7, 14 and 21 and challenging with 2.5% Toulene Diisocyanate from day 22 to 51 (on every alternate day) through intranasal route. β-Endorphin (5 µg/kg) was administered through the nasal route 1 h prior to sensitization and challenge. The effect of β-Endorphin on pulmonary inflammation and redox status along with parameters of oxidative stress were evaluated. We found that pre-treatment of β-Endorphin significantly reduced inflammatory infiltration in lung tissue and cell counts in bronchoalveolar lavage fluid. Also, pre-treatment of β-Endorphin reduced reactive oxygen species, Myeloperoxidase, Nitric Oxide, Protein and protein carbonylation, Glutathione Reductase, Malondialdehyde, IFN-γ, and TNF-α. Reversely, β-Endorphin significantly increased Superoxide dismutase, Catalase, glutathione, Glutathione-S-Transferase, and activation of NF-E2-related factor 2 (Nrf-2) via Kelch-like ECH-associated protein 1 (Keap1), independent pathway in the lung restoring architectural alveolar and bronchial changes. The present findings reveal the therapeutic potency of β-END in regulating asthma by Keap-1 independent regulation of Nrf-2 activity. The present findings reveal the therapeutic potency of β-Endorphin in regulating asthma.

Short-term exposure to ozone and asthma exacerbation in adults: A longitudinal study in China

Background

The relationships between short-term ozone exposure and the acute exacerbations of asthma in adults have not been fully studied. Existing studies commonly ignored the effects of ozone on mild or early asthma exacerbations.

Objective

To investigate the associations between short-term ozone exposure and asthma exacerbations in Chinese adults.

Methods

We administered health management for adult asthma patients through the Respiratory Home Platform and required them to monitor their lung function every morning and evening by themselves. Finally, a total of 4,467 patients in 18 Chinese cities were included in the current analyses, with 79,217 pairs of lung function records. The maximum daily 8-h average ozone concentrations were collected from fixed-site air quality monitoring stations. We calculated diurnal peak expiratory flow (PEF) variation using morning and evening measurements of PEF and then defined different severity of asthma exacerbations with diurnal PEF variations >10, 15, and 20%, respectively. A binomial distributed generalized additive mixture model combined with distribution non-linear models was applied to examine the association of ozone with asthma exacerbations. We further conducted stratified analyses by sex, age, season of lung function tests, and region.

Measurements and results

We found that short-term ozone exposure was independently associated with an elevated risk of asthma exacerbations defined by lung function and the effects could last for about 2 days. At lag 0-2 days, each 10 μg/m3 increment in ozone concentration was associated with odds ratios of 1.010 [95% confidence interval (CI): 1.003, 1.017], 1.014 (95% CI: 1.005, 1.023), and 1.017 (95% CI: 1.006, 1.028) for asthma exacerbations that were defined by diurnal PEF variation over 10, 15, and 20%, respectively. The associations remained significant after adjusting for other pollutants, and became unstable when using 24-h average ozone concentration. We also found that the associations were relatively stronger in males, those aged 45 years and older, and in the warm season.

Conclusions

Our results suggest that short-term ozone exposure can increase the risk of asthma exacerbations, even in the early stage of exacerbation. Male and older asthma patients may be more vulnerable to ozone air pollution, especially in the warm season.

The protective effect of butylated hydroxytoluene and 3-hydroxytyrosol on food allergy in mice

OBJECTIVE

To test the effect of two dietary antioxidants: butylated hydroxytoluene (BHT) and 3-hydroxytyrosol (3-HT) in experimental food allergy.

METHODS

BALB/c mice maintained on control diet or diet with BHT or 3-HT were sensitized with ovalbumin (OVA) or saline through transdermal exposure. Plasma OVA-specific IgE (OVA-IgE) and IgG1 (OVA-IgG1) antibody levels were determined using ELISA. Sensitized mice were challenged by oral gavage with OVA. Rectal temperature (RT) was measured before and after challenge. Mast cell degranulation was quantified by measuring the plasma levels of mouse mucosal mast cell protease-1 (mMCP-1). Flow cytometry was carried out to evaluate the percentage Th2 cells from the spleen.

RESULTS

Mice on either a 3-HT or BHT diet showed a significantly decreased IgE response to OVA sensitization and less severe anaphylaxis, as evidenced by a diminished drop in body temperature, attenuated clinical signs, a more rapid recovery and decreased mast cell degranulation (as determined by lower plasma mMCP-1 levels).

CONCLUSION

The present study indicates two dietary antioxidants: BHT and 3-HT may be protective against experimental food allergy. These results suggest 3-HT and BHT could potentially be useful for prevention of food allergy.

N-acetylcysteine decreases lung inflammation and fibrosis by modulating ROS and Nrf2 in mice model exposed to particulate matter

Background and Objectives: Air pollutants can induce and incite airway diseases such as asthma. N-acetylcysteine (NAC) affects signaling pathways involved in apoptosis, angiogenesis, cell growth and arrest, redox-regulated gene expression, and the inflammatory response. However, it is not known how NAC change redox-regulated gene expression in asthma mouse model exposed to particulate matter (PM). To investigate the effects of NAC on asthma mice exposed to PM through Reactive oxygen species (ROS), nuclear factor erythroid 2-related factor 2 (Nrf2), and mucin 5 (Muc5).Methods: To investigate the effects of NAC (100 mg/kg) on redox-regulated gene expression and lung fibrosis in a mouse model of asthma exposed to PM. A mice model of asthma induced by ovalbumin (OVA) or OVA plus titanium dioxide (OVA + TiO₂) was established using wild-type BALB/c female mice, and the levels of Nrf2 and mucin 5AC (Muc5ac) proteins following NAC treatment were examined by Western blotting and immunostaining. In addition, the protein levels of ROS were checked.Results: Airway hyperresponsiveness and inflammation, goblet cell hyperplasia, and lung fibrosis were higher in OVA, OVA + TiO₂ mice than in control mice. NAC diminished OVA + TiO₂-induced airway hyperresponsiveness and inflammation, goblet cell hyperplasia, and lung fibrosis. Levels of ROS, Nrf2, and Muc5ac protein were higher in lung tissue from OVA + TiO₂ mice than that from control mice and were decreased by treatment with NAC.Conclusions: NAC reduce airway inflammation and responsiveness, goblet cell hyperplasia, and lung fibrosis by modulating ROS and Nrf2.

Overview of the Mechanisms of Oxidative Stress: Impact in Inflammation of the Airway Diseases

Inflammation of the human lung is mediated in response to different stimuli (e.g., physical, radioactive, infective, pro-allergenic or toxic) such as cigarette smoke and environmental pollutants. They often promote an increase in inflammatory activities in the airways that manifest themselves as chronic diseases (e.g., allergic airway diseases, asthma, chronic bronchitis/chronic obstructive pulmonary disease (COPD) or even lung cancer). Increased levels of oxidative stress (OS) reduce the antioxidant defenses, affect the autophagy/mitophagy processes, and the regulatory mechanisms of cell survival, promoting inflammation in the lung. In fact, OS potentiate the inflammatory activities in the lung, favoring the progression of chronic airway diseases. OS increases the production of reactive oxygen species (ROS), including superoxide anions (O₂^-), hydroxyl radicals (OH) and hydrogen peroxide (H₂O₂), by the transformation of oxygen through enzymatic and non-enzymatic reactions. In this manner, OS reduces endogenous antioxidant defenses in both nucleated and non-nucleated cells. The production of ROS in the lung can derive from both exogenous insults (cigarette smoke or environmental pollution) and endogenous sources such as cell injury and/or activated inflammatory and structural cells. In this review, we describe the most relevant knowledge concerning the functional interrelation between the mechanisms of OS and inflammation in airway diseases.

Aryl Hydrocarbon Receptor in Oxidative Stress as a Double Agent and Its Biological and Therapeutic Significance

The aryl hydrocarbon receptor (AhR) has long been implicated in the induction of a battery of genes involved in the metabolism of xenobiotics and endogenous compounds. AhR is a ligand-activated transcription factor necessary for the launch of transcriptional responses important in health and disease. In past decades, evidence has accumulated that AhR is associated with the cellular response to oxidative stress, and this property of AhR must be taken into account during investigations into a mechanism of action of xenobiotics that is able to activate AhR or that is susceptible to metabolic activation by enzymes encoded by the genes that are under the control of AhR. In this review, we examine various mechanisms by which AhR takes part in the oxidative-stress response, including antioxidant and prooxidant enzymes and cytochrome P450. We also show that AhR, as a participant in the redox balance and as a modulator of redox signals, is being increasingly studied as a target for a new class of therapeutic compounds and as an explanation for the pathogenesis of some disorders.

Serum Myeloperoxidase as a Biomarker of Asthma Severity Among Adults: A Case Control Study

Background

The contribution of neutrophils is still indistinct in the inflammatory response of bronchial asthma (BAs). Myeloperoxidase (MPO) is an enzyme released from the primary azurophilic granules of the neutrophils. The study aimed to evaluate the levels of serum MPO as a biomarker for the assessment of the level of asthma control.

Methods

The study participants included 94 asthmatic patients and 86 healthy controls. The identification of asthma severity had assessed using the ''Global Initiative for Asthma guidelines''. Asthmatic adults had divided into three groups: Good (n= 22), partial (n= 30), and poor control (n= 44). Also, patients have been divided again into two groups (treated and untreated) for BAs.

Results

The predicted FEV1% and the peak expiratory flow (PEF/L) of all participants had verified by spirometry. The mean patients' age was 31.9±15.1 year, with a predominance of females. The mean asthma duration was 10.5±8.6 years. Mean spirometric parameters (FEV1 and PEF) were significantly lower among the patients (0.00). Significant higher MPO levels had observed among BAs patients (p-0.00). The MPO levels have not differed significantly with asthma levels and had significant differences with the history of treatment. There was a nonsignificant negative correlation between the mean MPO levels and the spirometry variables among the patients. ROC curves revealed a sensitivity, specificity, accuracy for MPO (80.9%, 72.1%, and 84.3%), respectively to predict asthmatic severity.

Conclusion

There were significantly higher MPO levels compared to healthy controls. Levels of serum MPO had a non-significant positive correlation with levels of asthma control, but a negative non-significant correlation with spirometric results.

Antioxidant for Neurological Diseases and Neurotrauma and Bioengineering Approaches

Antioxidants are a class of molecules with an innate affinity to neutralize reactive oxygen species (ROS), which are known to cause oxidative stress. Oxidative stress has been associated with a wide range of diseases mediated by physiological damage to the cells. ROS play both beneficial and detrimental roles in human physiology depending on their overall concentration. ROS are an inevitable byproduct of the normal functioning of cells, which are produced as a result of the mitochondrial respiration process. Since the establishment of the detrimental effect of oxidative stress in neurological disorders and neurotrauma, there has been growing interest in exploring antioxidants to rescue remaining or surviving cells and reverse the neurological damage. In this review, we present the survey of different antioxidants studied in neurological applications including neurotrauma. We also delve into bioengineering approaches developed to deliver antioxidants to improve their cellular uptake in neurological applications.

Apremilast mitigates interleukin (IL)-13-induced inflammatory response and mucin production in human nasal epithelial cells (hNECs)

Interleukin (IL)-13-associated inflammatory response is important for the pathogenesis of allergic rhinitis (AR). Apremilast is a phosphodiesterase-4 (PDE4) inhibitor approved for psoriasis treatment. Here, we investigated the potential effects of Apremilast against IL-13-induced injury in human nasal epithelial cells (hNECs). Firstly, Apremilast ameliorated oxidative stress in IL-13-challenged cells by decreasing the levels of reactive oxygen species (ROS) and the production of malondialdehyde (MDA). Secondly, Apremilast inhibited the expressions of IL-6 and IL-8. Moreover, Apremilast inhibited the expressions of the chemokines colony-stimulating factor 2 (CSF2) and chemokine ligand 11 (CCL11). Interestingly, exposure to IL-13 increased the expressions of mucin 4 and mucin 5AC (MUC5AC), which was ameliorated by treatment with Apremilast. Interestingly, we found that Apremilast inhibited the phosphorylation of c-Jun-N-terminal kinase (JNK). Importantly, Apremilast reduced the levels of c-fos and c-Jun, the two AP-1 subfamilies. The luciferase reporter assay demonstrates that Apremilast reduced the transcriptional activity of activator protein 1 (AP-1). Lastly, we found that Apremilast prevented the activation of nuclear factor kappa-B (NF-κB) by decreasing the levels of nuclear NF-κB p65 and the luciferase activity of the NF-κB reporter. In summary, we conclude that Apremilast possesses a protective effect against IL-13-induced inflammatory response and mucin production in hNECs by inhibiting the activity of AP-1 and NF-κB.

Early Elevation of Thioredoxin-1 Serum Levels Predicts 28-Day Mortality in Patients with Sepsis

Background

Sepsis is the leading cause of death in critically ill patients, and the prevention of which requires precise outcome prediction and early intervention. We evaluated the prognostic prediction value of serum thioredoxin-1 (Trx-1) as an anti-inflammatory factor in patients with sepsis.

Methods

As a prospective study, patients with sepsis admitted to the intensive care unit (ICU) of our hospital during 2020 were recruited. Medical history collection, sequential organ failure assessment (ΔSOFA), and laboratory tests were performed within 24 h of admission. Serum levels of Trx-1 and other inflammatory biomarkers were detected with samples dynamically collected before, during, and after septic shock. Patients were categorized as survivors and non-survivors according to survival status on day 28. Correlation between Trx-1 and other sepsis-associated parameters as well as the correlation of Trx-1 and other sepsis-associated parameters with 28-day mortality were evaluated. Prognostic factors were identified by Cox regression analyses.

Results

A total of 187 patients were recruited. Serum Trx-1 level was positively correlated with inflammatory factors (interleukin-6, C-reactive protein, procalcitonin) and index of sepsis severity (ΔSOFA score, partial pressure of oxygen/fraction of inspired oxygen), all of which were significantly higher in non-survivors than survivors. While Trx-1 level at different timepoints and its evolution over time significantly differed between survivors and non-survivors, the initial Trx-1 level outperformed the other parameters in predicting 28-day survival. With 38.27 ng/mL as the cutoff value, serum Trx-1 predicted 28-day survival with optimal sensitivity and specificity.

Conclusion

Early increases in serum levels of Trx-1 can predict 28-day mortality in sepsis patients in the ICU.

Oxido-inflammatory responses and histological alterations in rat lungs exposed to petroleum product fumes

Petroleum products-petrol, kerosene, and diesel-composed of volatile organic constituents contribute to air pollution. Exposure of gas station attendants (GSAs) to petroleum products fumes (PPFs) may account for occupation-related predisposition to respiratory toxicity and disease pathogenesis. We simulated GSA exposure to PPF inhalation and examined their effect on oxido-inflammatory responses, toxicity, and histopathological alterations in rat lungs, following 8-hours daily exposure for 60 and 90 days. Reactive oxygen and nitrogen species (RONS), oxidative stress and inflammatory biomarkers, namely: superoxide dismutase (SOD), reduced glutathione (GSH), glutathione peroxidase (GPx), glutathione-S-transferase (GST), TNF-α, IL-1β, xanthine oxidase (XO), nitric oxide (NO) activity were evaluated. Besides, histopathological examination of the lungs and trachea of exposed rats, PPF exposure resulted in significant (P < .05) increases in RONS, biomarkers of oxidative stress, pro-inflammation cytokines, and reduced (P < .05) GSH levels in rats, secondary to histopathological alteration in lungs and trachea cytoarchitecture examined in an exposure-duration-dependent manner. We conclude, therefore, that the observed biochemical and histological changes create a microenvironment that is permissive to diseases pathogenesis of the respiratory system via oxido-inflammatory mechanistic pathways.

Regulatory Effects of Nur77 on Airway Remodeling and ASMC Proliferation in House Dust Mite-Induced Asthma

Airway remodeling played a vital role in the development of asthma, and airway smooth muscle (ASM) mass was its hallmark. However, few strategies targeting ASM remodeling were developed in treating asthma. Nur77 was the transcription factor nuclear receptor involved in the pathogenesis of several lung diseases. Nur77 distribution and expression were determined in an HDM-mediated allergic asthma model. Its effect on airway hyperresponsiveness (AHR), chronic inflammation, and ASM remodeling in asthmatic mice was evaluated using a lentivirus-mediated shRNA. Possible mechanisms were explored by examining Nur77 actions and its underlying pathways in primary human AMC cells (ASMCs). In this study, we reported that Nur77 expression was mainly distributed along ASM and increased in lungs of HDM-challenged mice. Nur77 depletion by lentivirus-mediated shRNA ameliorated AHR, chronic inflammation, goblet cell hyperplasia, and airway remodeling in the asthmatic mouse model. By means of primary human ASMC, we discovered that Nur77 upregulation by HDM stimulation promoted cell proliferation and ROS production, as well as reduced antioxidant gene expression. These alterations might associate with MFN2/MAPK/AKT pathways. These findings broadened our understanding of airway remodeling and ASMC proliferation, which might provide a novel therapeutic target for asthma patients.

Neonatal Jaundice: The Other Side of the Coin in the Development of Allergy

OBJECTIVE

The current study aims to assess the association between different characteristics of neonatal jaundice and common types of allergic diseases in childhood (as bronchial asthma, acute urticaria, and allergic rhinitis).

STUDY DESIGN

A case-control study is conducted on 300 allergic children and 300 healthy children as a control group at Fayoum University Hospital. The study was conducted over a span of 2 years, from May 2016 to May 2018. Bronchial asthma, allergic rhinitis, and acute urticaria diagnoses were based on physician clinical examination using specific guidelines for each. For the data regarding children's demographic and maternal characteristics, a structured questionnaire was used. Regarding neonatal jaundice, data were collected from the patients' hospital records.

RESULTS

Children with neonatal jaundice are more likely to develop allergy with 57% higher than neonates without jaundice. Early onset jaundice and treatment by phototherapy have statistically significant association with the development of allergic diseases.

CONCLUSION

Different aspects of neonatal jaundice are associated with the development of common allergic diseases in children.

Serum Zinc, Selenium and Total Antioxidant Contents of Nigerian Children with Asthma: Association with Disease Severity and Symptoms Control

BACKGROUND

Micronutrients and antioxidants may ameliorate oxidative stress. This study aimed to determine the serum Zinc (Zn), Selenium (Se) and Total Antioxidant Contents (TAC) of Nigerian children with asthma and relate these to disease severity and symptoms control.

METHODS

Children aged 2-15 years with asthma and age and sex matched controls were consecutively recruited. The children's serum Zn, Se and TAC were assayed and compared.

RESULTS

Eighty children each with asthma and controls participated in the study. Serum Zn (71.0 ± 30.3 µg/dl vs. 84.2 ± 31.7 µg/dl; p = 0.008), Se (67.3 ± 29.8 µg/l vs. 80.0 ± 31.7 µg/l; p = 0.033) and TAC [median (interquartile range) 5.2 (3.8-6.8) ng/dl vs. 6.2 (4.3-8.0) ng/dl; p = 0.019] were lower in children with asthma. Serum Se (65.7 ± 29.1 µg/l vs. 92.4 ± 28.6 µg/l; p = 0.001) was lower in those with moderate/severe than mild disease, but no association with symptoms control (p > 0.05).

CONCLUSION

Micronutrient supplementation may be beneficial in Nigerian children with asthma as they have relatively lower antioxidant micronutrients than nonasthmatics.

Lindera obtusiloba Attenuates Oxidative Stress and Airway Inflammation in a Murine Model of Ovalbumin-Challenged Asthma

Lindera obtusiloba is widespread in northeast Asia and used for treatment of improvement of blood circulation and anti-inflammation. In this study, we investigated anti-inflammatory and anti-oxidant effects of the methanolic extract of L. obtusiloba leaves (LOL) in an ovalbumin (OVA)-challenged allergic asthma model and tumor necrosis factor (TNF)-α-stimulated NCI-H292 cell. Female BALB/c mice were sensitized with OVA by intraperitoneal injection on days 0 and 14, and airway-challenged with OVA from days 21 to 23. Mice were administered 50 and 100 mg/kg of LOL by oral gavage 1 h before the challenge. LOL treatment effectively decreased airway hyper-responsiveness and inhibited inflammatory cell recruitment, Th2 cytokines, mucin 5AC (MUC5AC) in bronchoalveolar lavage fluid in OVA-challenged mice, which were accompanied by marked suppression of airway inflammation and mucus production in the lung tissue. LOL pretreatment inhibited the phosphorylation of mitogen-activated protein kinases (MAPKs) and nuclear factor-kappa B (NF-κB) with suppression of activator protein (AP)-1 and MUC5AC in the lung tissue. LOL also down-regulated expression of inflammatory cytokines, and inhibited the activation of NF-κB in TNF-α-stimulated NCI-H292 cells. LOL elevated the translocation of nuclear factor-erythroid 2-related factor (Nrf-2) into nucleus concurrent with increase of heme oxyngenase-1 (HO-1) and NAD(P)H quinine oxidoreductase 1 (NQO1). Moreover, LOL treatment exhibited a marked increase in the anti-oxidant enzymes activities, whereas effectively suppressed the production of reactive oxygen species and nitric oxide, as well as lipid peroxidation in lung tissue of OVA-challenged mice and TNF-α-stimulated NCI-H292 cells. These findings suggest that LOL might serve as a therapeutic agent for the treatment of allergic asthma.

Effect of Lavandula dentata extract on Ovalbumin-induced Asthma in Male Guinea Pigs

Asthma is an inflammatory disease of the lungs, and it causes oxidative stress. Lavandula dentata is an aromatic herb with anti-oxidative and anti-inflammatory activities. This study examined the activity of L. dentata extract on a guinea pig model of asthma. Adult males were divided into five groups: First group was control, second was asthma model induced by OVA, third was treated with L. dentata extract orally (300 mg/kg) for 21 days; the fourth was an asthma model with L. dentata extract (300 mg/kg) and fifth was treated with Tween 80 for 21 days. OVA treatment increased IgE, triglycerides, total cholesterol, glucose levels in serum, WBC count in blood and MDA in lungs. Also, OVA reduced SOD activity, GSH content in lungs, and GGT activity in serum (p<0.05). L. dentata extract treatment in asthma model reduced elevated IgE, triglycerides, total cholesterol, glucose levels in serum, and MDA in lungs (p<0.05), while it increased GSH content in lungs (p<0.05). These results suggest the possibility that L . dentata extract can exert suppressive effects on asthma, and may provide evidence that it is a useful agent for the treatment of allergic airway disease, it also limits oxidative stress induced by OVA. L. dentata extract appears to have hypolipidemic and hypoglycemic activities.

Mechanisms of ultrafine particle-induced respiratory health effects

Particulate matter (PM) is the principal component of air pollution. PM includes a range of particle sizes, such as coarse, fine, and ultrafine particles. Particles that are <100 nm in diameter are defined as ultrafine particles (UFPs). UFPs are found to a large extent in urban air as both singlet and aggregated particles. UFPs are classified into two major categories based on their source. Typically, UFPs are incidentally generated in the environment, often as byproducts of fossil fuel combustion, condensation of semivolatile substances or industrial emissions, whereas nanoparticles are manufactured through controlled engineering processes. The primary exposure mechanism of PM is inhalation. Inhalation of PM exacerbates respiratory symptoms in patients with chronic airway diseases, but the mechanisms underlying this response remain unclear. This review offers insights into the mechanisms by which particles, including UFPs, influence airway inflammation and discusses several mechanisms that may explain the relationship between particulate air pollutants and human health, particularly respiratory health. Understanding the mechanisms of PM-mediated lung injury will enhance efforts to protect at-risk individuals from the harmful health effects of air pollutants.

Imperatorin alleviates ROS-mediated airway remodeling by targeting the Nrf2/HO-1 signaling pathway

In this study, we investigated the role and mechanism of imperatorin (IMP) in chronic inflammation and airway remodeling. The levels of TNF-α, IL-1β, IL-6, IL-8, VEGF, α-SMA, and ROS were detected by ELISA, immunohistochemistry (IHC), immunofluorescence, and Western blot. In addition, we evaluated the effect of IMP on MAPK, PI3K/Akt, NF-κB, and Nrf2/HO-1 signaling pathways. IMP treatment obviously attenuated the production of inflammatory cytokines and inflammatory cells in bronchoalveolar lavage fluid of OVA-induced airway remodeling model. Meanwhile, it significantly inhibited inflammatory cell infiltration, goblet cell hyperplasia, collagen deposition, VEGF production, α-SMA, and ROS expression. Our study has shown that IMP could regulate the signaling pathways including MAPK, PI3K/Akt, NF-κB, and Nrf2/HO-1 to release the inflammatory responses. IMP might attenuate airway remodeling by the down-regulation of Nrf2/HO-1/ROS/PI3K/Akt, Nrf2/HO-1/ROS/MAPK, and Nrf2/HO-1/ROS/NF-κB signaling pathways.

Chemical composition, antioxidant activities, in an allergic asthma model, of Olea europaea L. leaf extracts from Collo (Skikda, Algeria)

This study is an attempt to characterize the chemical composition and antioxidant activity of olive leaves variety (namely Bouricha variety) that is very widespread in the East of Algeria. The aqueous extract (AE) of leaves was initially analyzed for its phenolic profile. Using the liquid chromatography coupled to tandem mass spectrometry analysis, it was possible to identify the predominant components in the AE of the leaves. This extract was hydrolyzed with acid and gave hydroxytyrosol (HT). AE and HT were evaluated for their 1,1-diphenyl-2-picrylhydrazyl radical scavenging capacity, ferric reducing antioxidant power and total antioxidant activity by phosphomolybdenum method. The antioxidant and anti-asthmatic activities of these extracts were examined in a model of experimental asthma in Wistar rats. For measuring the intensity of the airway inflammation, oxidative stress parameters were analyzed in lungs and a histological study of this tissue was performed. The obtained results showed that the sensitization of the ovalbumin (OVA) group induced lung inflammation and severe lipid peroxidation (LPO) revealed by a significant increase in malondialdehyde (MDA) levels and a decrease in the non-enzymatic and enzymatic antioxidant systems. However, the administration of AE and HT extracts significantly improved the antioxidant state in asthma disease and provided evidence for the relation between phenolic compounds and the high antioxidant activity of olive leaves extracts, especially HT more than AE.

Function of cAMP scaffolds in obstructive lung disease: Focus on epithelial-to-mesenchymal transition and oxidative stress

Over the past decades, research has defined cAMP as one of the central cellular nodes in sensing and integrating multiple pathways and as a pivotal role player in lung pathophysiology. Obstructive lung disorders, such as chronic obstructive pulmonary disease (COPD), are characterized by a persistent and progressive airflow limitation and by oxidative stress from endogenous and exogenous insults. The extent of airflow obstruction depends on the relative deposition of different constituents of the extracellular matrix, a process related to epithelial-to-mesenchymal transition, and which subsequently results in airway fibrosis. Oxidative stress from endogenous and also from exogenous sources causes a profound worsening of COPD. Here we describe how cAMP scaffolds and their different signalosomes in different subcellular compartments may contribute to COPD. Future research will require translational studies to alleviate disease symptoms by pharmacologically targeting the cAMP scaffolds. LINKED ARTICLES: This article is part of a themed section on Adrenoceptors-New Roles for Old Players. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.14/issuetoc.

The role of serum nuclear factor erythroid 2-related factor 2 in childhood bronchial asthma

Background: Asthma is one of the most common chronic airway disease of childhood. Poor asthma control has been associated with antioxidant deficiencies. Objective: To assess the association of bronchial asthma in Egyptian children with serum nuclear factor erythroid 2-related factor2 (NRF2) and its relation to disease severity. Subjects and methods: The study included 60 asthmatic children with comparable 60 controls (age ranged from 6-16 years). Subjects were classified according to the severity of asthma into mild or moderate asthma in group I, and severe asthma in group II. Antioxidant markers including superoxide-dismutase (SOD), glutathione peroxidase (GPX) and NRF2 were assessed once in blood and serum of both subjects and controls. Results: Mean serum NRF2 and GPX were significantly lower in asthmatic group than controls group (26.36 ± 4.18 pg/mL and 5.76 ± 0.81 mU/mL vs 29.05 ± 3.87 and 6.23 ± 0.97 respectively, p < 0.05). No significant difference was detected regarding SOD (p > 0.05). In severe bronchial asthma, mean serum NRF2 and GPX were significantly lower than in mild and moderate asthma (24.29 ± 1.86 pg/mL and 5.56 ± 0.67 mU/mL vs 27.95 ± 4.77 and 6.03 ± 0.90 respectively, p < 0.05). No significant difference was found in SOD regarding severity of bronchial asthma. Low NRF2 was the only predictor of the severity of bronchial asthma (OR = 0.749 and 95% CI 0.595 - 0.942). Conclusion: The pathogenesis of childhood bronchial asthma may be associated with low serum NRF2 which may be a strong predictor of the disease severity.

Cystine-based MBioF for Maintaining the Antioxidant-Oxidant Balance in Airway Diseases

Reactive oxygen species, contributing to oxidant-antioxidant imbalance, initiate damage to the airways cells, inflammatory processes, and further pathophysiological effects. Enhancing antioxidant properties is the main prophylactic and therapeutic challenge. In this work, a newly synthesized and biocompatible structure of the metal-biomolecule frameworks (MBioF) harnessing cystine as a linker and magnesium as metal nodes is presented. This structure provides crucial sulfhydryl groups of cysteine, with antioxidant activity, released stepwise in the site of delivery. We prove that once released, the compounds of MBioF increase the intracellular level of cysteine and total antioxidative capability of airway cells. Presented MBioF structures offer new perspectives for clinical applications as therapeutics or preventatives maintaining the antioxidant-oxidant balance.

Hyperbilirubinemia, Phototherapy, and Childhood Asthma

OBJECTIVES

Our aim was to quantify the associations of both hyperbilirubinemia and phototherapy with childhood asthma using a population-based cohort with total serum bilirubin (TSB) levels.

METHODS

Retrospective cohort study of infants born at ≥35 weeks' gestation in the Kaiser Permanente Northern California health system (n = 109 212) from 2010 to 2014. Cox models were used to estimate hazard ratios (HRs) for a diagnosis of asthma.

RESULTS

In the study, 16.7% of infants had a maximum TSB level of ≥15 mg/dL, 4.5% of infants had a maximum TSB level of ≥18 mg/dL, and 11.5% of infants received phototherapy. Compared with children with a maximum TSB level of 3 to 5.9 mg/L, children with a TSB level of 9 to 11.9 mg/dL, 12 to 14.9 mg/dL, and 15 to 17.9 mg/dL were at an increased risk for asthma (HR: 1.22 [95% confidence interval (CI): 1.11-1.3], HR: 1.18 [95% CI: 1.08-1.29], and HR: 1.30 [95% CI: 1.18-1.43], respectively). Children with a TSB level of ≥18 mg/dL were not at an increased risk for asthma (HR: 1.04; 95% CI: 0.90-1.20). In propensity-adjusted analyses, phototherapy was not associated with asthma (HR: 1.07; 95% CI: 0.96-1.20).

CONCLUSIONS

Modest levels of hyperbilirubinemia were associated with an increased risk of asthma, but an association was not seen at higher levels. No dose-response relationship was seen. Using phototherapy to prevent infants from reaching these modest TSB levels is unlikely to be protective against asthma.

Inhibition of phosphodiesterase 2 reverses gp91phox oxidase-mediated depression- and anxiety-like behavior

Phosphodiesterase 2 (PDE2) plays an important role in treatment of stress-related depression through regulation of antioxidant defense and neuroprotective mechanisms. However, the causal relationship between PDE2 and the prevalence of depression and anxiety upon exposure to oxidative stress has not been investigated. The present study examined whether the effects of PDE2 inhibition on oxidative stress were directly involved in reduced ROS by regulating NADPH subunits gp91phox oxidase. The results suggested that the PDE2 inhibitor Bay 60-7550 reversed oxidative stress-induced behavioral signature, i.e. depression and anxiety. Pretreatment with the oxidizing agent DTNB completely blocked, while the reducing agent DTT and the NADPH oxidase inhibitor apocynin potentiated the effects of Bay 60-7550 on behavioral abnormalities, demonstrating the relationship between PDE2 and oxidative stress. Consistently, an in vitro test revealed the positive correlation between ROS and PDE2 levels. Moreover, Bay 60-7550 decreased corticosterone-induced gp91phox expression, which is the source of ROS. The subsequent study suggested that Bay 60-7550 induced decrease in ROS and increase in cAMP/cGMP, pVASP, pCREB, and the neurotrophic factor BDNF levels, which were completely blocked by CRISPR/Cas9-mediated gp91phox overexpression and potentiated by gp91phox siRNA-based antioxidant strategies. The in vivo test in stressed mice further suggested that gp91phox overexpression completely blocked the antidepressant- and anxiolytic-like effects of Bay 60-7550, while gp91phox knockdown enhanced such effects. These results provide solid evidence that the antidepressant- and anxiolytic-like effects of Bay 60-7550 against stress are causally related to down-regulation of gp91phox and activation of the cAMP/cGMP-pVASP-CREB-BDNF signaling pathway.

Oxidative stress in chronic lung disease: From mitochondrial dysfunction to dysregulated redox signaling

The lung is a delicate organ with a large surface area that is continuously exposed to the external environment, and is therefore highly vulnerable to exogenous sources of oxidative stress. In addition, each of its approximately 40 cell types can also generate reactive oxygen species (ROS), as byproducts of cellular metabolism and in a more regulated manner by NOX enzymes with functions in host defense, immune regulation, and cell proliferation or differentiation. To effectively regulate the biological actions of exogenous and endogenous ROS, various enzymatic and non-enzymatic antioxidant defense systems are present in all lung cell types to provide adequate protection against their injurious effects and to allow for appropriate ROS-mediated biological signaling. Acute and chronic lung diseases are commonly thought to be associated with increased oxidative stress, evidenced by altered cellular or extracellular redox status, increased irreversible oxidative modifications in proteins or DNA, mitochondrial dysfunction, and altered expression or activity of NOX enzymes and antioxidant enzyme systems. However, supplementation strategies with generic antioxidants have been minimally successful in prevention or treatment of lung disease, most likely due to their inability to distinguish between harmful and beneficial actions of ROS. Recent studies have attempted to identify specific redox-based mechanisms that may mediate chronic lung disease, such as allergic asthma or pulmonary fibrosis, which provide opportunities for selective redox-based therapeutic strategies that may be useful in treatment of these diseases.

TH17-Induced Neutrophils Enhance the Pulmonary Allergic Response Following BALB/c Exposure to House Dust Mite Allergen and Fine Particulate Matter From California and China

Asthma is a global and increasingly prevalent disease. According to the World Health Organization, approximately 235 million people suffer from asthma. Studies suggest that fine particulate matter (PM2.5) can induce innate immune responses, promote allergic sensitization, and exacerbate asthmatic symptoms and airway hyper-responsiveness. Recently, severe asthma and allergic sensitization have been associated with T-helper cell type 17 (TH17) activation. Few studies have investigated the links between PM2.5 exposure, allergic sensitization, asthma, and TH17 activation. This study aimed to determine whether (1) low-dose extracts of PM2.5 from California (PMCA) or China (PMCH) enhance allergic sensitization in mice following exposure to house dust mite (HDM) allergen; (2) eosinophilic or neutrophilic inflammatory responses result from PM and HDM exposure; and (3) TH17-associated cytokines are increased in the lung following exposure to PM and/or HDM. Ten-week-old male BALB/c mice (n = 6-10/group) were intranasally instilled with phosphate-buffered saline (PBS), PM+PBS, HDM, or PM+HDM, on days 1, 3, and 5 (sensitization experiments), and PBS or HDM on days 12-14 (challenge experiments). Pulmonary function, bronchoalveolar lavage cell differentials, plasma immunoglobulin (Ig) protein levels, and lung tissue pathology, cyto-/chemo-kine proteins, and gene expression were assessed on day 15. Results indicated low-dose PM2.5 extracts can enhance allergic sensitization and TH17-associated responses. Although PMCA+HDM significantly decreased pulmonary function, and significantly increased neutrophils, Igs, and TH17-related protein and gene levels compared with HDM, there were no significant differences between HDM and PMCH+HDM treatments. This may result from greater copper and oxidized organic content in PMCA versus PMCH.

miR-155 Modulates Cockroach Allergen- and Oxidative Stress-Induced Cyclooxygenase-2 in Asthma

Exposure to cockroach allergen is a strong risk factor for developing asthma. Asthma has been associated with allergen-induced airway epithelial damage and heightened oxidant stress. In this study, we investigated cockroach allergen-induced oxidative stress in airway epithelium and its underlying mechanisms. We found that cockroach extract (CRE) could induce reactive oxygen species (ROS) production, particularly mitochondrial-derived ROS, in human bronchial epithelial cells. We then used the RT² Profiler PCR array and identified that cyclooxygenase-2 (COX-2) was the most significantly upregulated gene related to CRE-induced oxidative stress. miR-155, predicted to target COX-2, was increased in CRE-treated human bronchial epithelial cells, and was showed to regulate COX-2 expression. Moreover, miR-155 can bind COX-2, induce COX-2 reporter activity, and maintain mRNA stability. Furthermore, CRE-treated miR-155^-/- mice showed reduced levels of ROS and COX-2 expression in lung tissues and PGE₂ in bronchoalveolar lavage fluid compared with wild-type mice. These miR-155^-/- mice also showed reduced lung inflammation and Th2/Th17 cytokines. In contrast, when miR-155^-/- mice were transfected with adeno-associated virus carrying miR-155, the phenotypic changes in CRE-treated miR-155^-/- mice were remarkably reversed, including ROS, COX-2 expression, lung inflammation, and Th2/Th17 cytokines. Importantly, plasma miR-155 levels were elevated in severe asthmatics when compared with nonasthmatics or mild-to-moderate asthmatics. These increased plasma miR-155 levels were also observed in asthmatics with cockroach allergy compared with those without cockroach allergy. Collectively, these findings suggest that COX-2 is a major gene related to cockroach allergen-induced oxidative stress and highlight a novel role of miR-155 in regulating the ROS-COX-2 axis in asthma.

Overexpression of Annexin A1 protects against benzo[a]pyrene‑induced bronchial epithelium injury

The incidence of asthma is increasing worldwide. Bronchial epithelium injury is common in asthma. The regulatory role of Annexin A1 (ANXA1) in bronchial epithelium injury is currently not well understood. The aim of the present study was to evaluate the role of ANXA1 on bronchial epithelium injury. The cell viability and levels of apoptosis were respectively tested by Cell Counting Kit-8 and flow cytometry. Reactive oxygen species (ROS) content and the activity of oxidative indicators were assessed by commercial kits. Enzyme linked immunosorbent assay was performed to detect the activity of active caspase-3. Reverse transcription-quantitative polymerase chain reaction and western blot assays were used to determine the expression levels of the target factors. The results demonstrated that ANXA1 improved the viability of benzo[a]pyrene (Bap)-treated bronchial epithelial cells. The Bap-induced oxidative stress was mitigated by the reduction in ROS generation, and the regulation of the activity of superoxide dismutase, glutathione peroxidases, malondialdehyde and lactic dehydrogenase. In addition, apoptosis was decreased by ANXA1 via the reduction of the expression of B-cell lymphoma 2 (Bcl-2), and the increase in the expression of Bcl-2-associated X protein and cyclin D1. Furthermore, the expression of phosphatase and tensin homolog (PTEN) and focal adhesion kinase (FAK) was rescued and the phosphorylation of phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) was depressed by ANXA1, when compared with the Bap group. SF1670 treatment reversed the anti-apoptotic effect of ANXA1. In conclusion, the results highlighted the protective effects of ANXA1 on bronchial epithelium injury, which most likely occurred via the PTEN/FAK/PI3K/Akt signaling pathway. Thus, the present study contributes to a potential therapeutic strategy for asthma patients.

Serum Zinc Level in Asthmatic and Non-Asthmatic School Children

Asthma is one of the most common chronic disorders among children. Zinc (Zn) is an essential dietary antioxidant and may have a special role in assisting the airways of asthmatic subjects. The primary objective of this study was to measure serum Zn levels among asthmatic school children and to compare this to the serum Zn level in non-asthmatic children. The secondary objective was to investigate the relationship between Zn levels and the degree of asthma control. A cross-sectional study following forty asthmatic children and forty matched non-asthmatic children of both genders was conducted. Weight, height, body mass index (BMI), BMI Z-scores, serum Zn, hemoglobin, total protein, and albumin concentrations were measured in both groups. Serum immunoglobulin E (IgE) levels, the forced expiratory volume in 1 second (FEV1), and dosage of inhaled steroids were measured in asthmatic school children. The results show the mean Zn level among asthmatic children was 12.78 ± 1.8 μmol/L. Hypozincemia was detected in four asthmatic children. Asthma and control groups were matched in age, gender, and BMI Z score (p > 0.05). No significant difference was observed in Zn levels, hemoglobin, albumin, and total protein between both groups (p > 0.05). Among asthmatics, Zn levels were not significantly associated with the degree of asthma control (well controlled, mean Zn = 12.9 ± 1.5, partially controlled, mean Zn = 11.9 ± 1.6, and uncontrolled, mean Zn = 3.62 ± 2.2) (p = 0.053). The Zn level was not correlated with the FEV1 Z score. There was no significant association between Zn level and the dosage of inhaled steroids or IgE concentrations (p > 0.05). The findings show that Zn may not play a major role in the degree of asthma control. Larger studies are needed to confirm these results.

Inhalation of hydrogen gas attenuates airway inflammation and oxidative stress in allergic asthmatic mice

Background

Asthma is a worldwide common chronic airway disease that cannot be cured and results in the huge burden in public health. Oxidative stress was considered an important mechanism in the pathogenesis of asthma. Hydrogen gas been demonstrated to function as a novel antioxidant and exert therapeutic antioxidant activity in a number of diseases and the function of this nontoxic gas in asthma was unclear. The purpose of the study aims to examine the effect of inhalation hydrogen gas on the pathophysiology of a mouse model of asthma.

Methods

A murine model of ovalbumin (OVA)-induced allergic airway inflammation was used in this study. Briefly, Mice were sensitized to ovalbumin and received inhalation of 67% high concentration of hydrogen gas for 60 min once a day for 7 consecutive days after OVA or PBS challenge respectively. Lung function was assessed in the apparatus with 4 channels of biological signal system. Morphology and goblet cell hyperplasia were stained by H/E and Periodic acid-Schiff staining. Cytologic classification in the bronchial alveolar lavage fluid (BALF) was analyzed by Wright Giemsa staining. Serum, BALF and lung tissue were collected for biochemical assay. One-way analysis of variance (ANOVA) was used to determine statistical significance between groups. Multiple comparisons were made by Bonferroni’s Multiple Comparison Test by using GraphPad Prism 5 software.

Results

Inhalation of hydrogen gas abrogated ovalbumin-induced the increase in lung resistance. Concomitantly, the asthmatic mice showed severe inflammatory infiltration and goblet cell hyperplasia which were reversed by hydrogen gas inhalation. Hydrogen gas inhalation reduced significantly the number of total cells, eosinophils and lymphocytes in BALF. Increased level of IL-4, IL-13, TNF-α and CXCL15 in the BALF and IL-4 in the serum were decreased significantly after inhalation. Hydrogen gas inhalation markedly upregulated the activity of decreased superoxide dismutase and significantly attenuated the increased level of malondialdehyde and myeloperoxidase.

Conclusions

Hydrogen gas inhalation improves lung function and protects established airway inflammation in the allergic asthmatic mice model which may be associated with the inhibition of oxidative stress process. This study provides a potential alternative therapeutic opportunity for the clinical management of asthma.

The effects of exercise on depressive- and anxiety-like behaviors as well as lung and hippocampus oxidative stress in ovalbumin-sensitized juvenile rats

Allergic asthma during early life period has been reported to be associated with neurochemical and behavioral disorders, including anxiety and depression. We aimed to determine the effects of exercise on depressive- and anxiety-like behaviors as well as lung and hippocampus oxidative stress in ovalbumin (OVA)-sensitized juvenile rats. Animals were divided into 4 groups including control (non-exercised and non-sensitized), Exe (exercise and non-sensitized); OVA (non-exercised and OVA-sensitized); and OVA+Exe (exercised and OVA-sensitized). The rats were subjected to chronic OVA sensitization followed by 4 weeks of treadmill exercise training. Compared to the control group, the OVA group had an increase in anxiety- and depressive-like behavior, lung inflammation, and oxidative stress index in the lung and hippocampus. Compared to the OVA group, the OVA+Exe group had a decline in anxiety- and depressive-like behavior, lung inflammation, and oxidative stress index in the lung and hippocampus. No significant difference in terms of the above-mentioned parameters, were found between the control group and the Exe group. Exercise decreased depressive- and anxiety-like behaviors in OVA-sensitized juvenile rats; this effect might have been mainly mediated by improvement in antioxidant system.

Leptin positively regulates MUC5AC production and secretion induced by interleukin-13 in human bronchial epithelial cells

Mucus hypersecretion and plugging of lower respiratory tract airways due to mucus plugs have long been recognized as the leading cause of the morbidity and mortality in asthma. MUC5AC protein is a major component of airway mucus. Here, we showed that interleukin (IL)-13 induced MUC5AC production and secretion, and leptin expression in the human bronchial epithelial cell line-16 (HBE16) cells in a concentration-dependent manner. Leptin knockdown suppressed MUC5AC production and secretion induced by IL-13. We further investigated the molecular mechanism by which leptin functioned, and found that leptin regulated IL-13-induced MUC5AC production and secretion via the JAK2-STAT3 pathway. Subsequently, Munc18b, a limiting component of the exocytic machinery of airway epithelial and mast cells, was found that when knockdown, MUC5AC secretion was significantly inhibited. SABiosciences ChIP search tool identified three STAT3 binding sites with Munc18b promoter. Chromatin immunoprecipitation analysis further confirmed that Stat3 upregulated Munc18b expression by directly binding to its promoter. These data suggested that leptin promotes MUC5AC secretion via JAK2-STAT3-MUNC18b regulatory network. Taken together, our data highlight a positive feedback role and molecular mechanism for leptin in the control of MUC5AC production and secretion from airway epithelial cells stimulated by IL-13, which encourage further exploration of the therapeutic potentials of manipulating leptin in the treatment of mucus hypersecretion in chronic inflammation lung diseases.

Increased antioxidant activity after exposure of ozone in murine asthma model

Background

Ozone is well known as an important component of ambient air pollutants. Ozone can aggravate respiratory symptoms in patients with bronchial asthma, but, not in healthy person. We hypothesized asthma itself may show different response to ozone compared to nonasthma.

Objective

This study was performed to evaluate the differences of response to ozone between normal and asthmatic mice model in terms of status of oxidant injury and antioxidant activity.

Methods

Three parts per million of ozone was exposed to ovalbumin (OVA)-induced murine asthma model for 3 hours at 3, 7, 14, 21 days after completion of asthma model. Airway responsiveness to methacholine was measured after completion of asthma model. Bronchoalveolar lavage (BAL), protein extraction from lung for Western blot and immunohistochemistry of 4-hydroxy-2-nonenal (4-HNE), proliferating cell nuclear antigen (PCNA), NF-E2 related factor 2 (Nrf-2), and activity of glutathione were performed at before and each ozone exposure day.

Results

Airway hyper-responsiveness and increased eosinophils in BAL fluid were observed in asthma model. In asthma model, the expression of 4-HNE already more increased at baseline (without ozone) compared to those in sham model. This increased expression is more enhanced at 3 days after ozone exposure. The expression of PCNA was significantly increased in OVA-model compared to those in sham model. The expression of Nrf-2 was observed at baseline, and 3 and 7 days after exposure ozone in asthma model, but not in sham model. The activity of glutathione increased significantly after exposure of ozone, but not in sham model.

Conclusion

Murine asthma model has enhanced oxygen toxicity and antioxidant activity response to ozone.

Ablation of Glutaredoxin-1 Modulates House Dust Mite-Induced Allergic Airways Disease in Mice

Protein S-glutathionylation (PSSG) is an oxidant-induced post-translational modification of protein cysteines that impacts structure and function. The oxidoreductase glutaredoxin-1 (Glrx1) under physiological conditions catalyzes deglutathionylation and restores the protein thiol group. The involvement of Glrx1/PSSG in allergic inflammation induced by asthma-relevant allergens remains unknown. In the present study, we examined the impact of genetic ablation of Glrx1 in the pathogenesis of house dust mite (HDM)-induced allergic airways disease in mice. Wild-type (WT) or Glrx1(-/-) mice were instilled intranasally with HDM on 5 consecutive days for 3 weeks. As expected, overall PSSG was increased in Glrx1(-/-) HDM mice as compared with WT animals. Total cells in bronchoalveolar lavage fluid were similarly increased in HDM-treated WT and Glrx1(-/-) mice. However, in response to HDM, mice lacking Glrx1 demonstrated significantly more neutrophils and macrophages but fewer eosinophils as compared with HDM-exposed WT mice. mRNA expression of the Th2-associated cytokines IL-13 and IL-6, as well as mucin-5AC (Muc5ac), was significantly attenuated in Glrx1(-/-) HDM-treated mice. Conversely, mRNA expression of IFN-γ and IL-17A was increased in Glrx1(-/-) HDM mice compared with WT littermates. Restimulation of single-cell suspensions isolated from lungs or spleens with HDM resulted in enhanced IL-17A and decreased IL-5 production in cells derived from inflamed Glrx1(-/-) mice compared with WT animals. Finally, HDM-induced tissue damping and elastance were significantly attenuated in Glrx1(-/-) mice compared with WT littermates. These results demonstrate that the Glrx1-PSSG axis plays a pivotal role in HDM-induced allergic airways disease in association with enhanced type 2 inflammation and restriction of IFN-γ and IL-17A.

Recent developments in the role of reactive oxygen species in allergic asthma

Allergic asthma has a global prevalence, morbidity, and mortality. Many environmental factors, such as pollutants and allergens, are highly relevant to allergic asthma. The most important pathological symptom of allergic asthma is airway inflammation. Accordingly, the unique role of reactive oxygen species (ROS) had been identified as a main reason for this respiratory inflammation. Many studies have shown that inhalation of different allergens can promote ROS generation. Recent studies have demonstrated that several pro-inflammatory mediators are responsible for the development of allergic asthma. Among these mediators, endogenous or exogenous ROS are responsible for the airway inflammation of allergic asthma. Furthermore, several inflammatory cells induce ROS and allergic asthma development. Airway inflammation, airway hyper-responsiveness, tissue injury, and remodeling can be induced by excessive ROS production in animal models. Based on investigations of allergic asthma and ROS formation mechanisms, we have identified several novel anti-inflammatory therapeutic treatments. This review describes the recent data linking ROS to the pathogenesis of allergic asthma.

Zinc Supplementation in Children with Asthma Exacerbation

Zinc deficiency has demonstrated an association with the risk of asthma. This study aimed to evaluate the efficacy of zinc supplementation in reducing the severity of childhood asthma exacerbation. A number of 42 children with asthma exacerbation admitted to the hospital were randomized to receive either zinc bis-glycinate (30 mg elemental zinc/day) or a placebo in adjuvant to the standard treatment. The pediatric respiratory assessment measure (PRAM) was used to measure the asthma severity. The primary outcome was a change in asthma severity from the baseline to the end of study. The study found that PRAM score in the zinc group showed a more rapid decrease compared to the control group at the 24-hour (2.2±1.3 vs. 1.2±1.3; P = 0.015) and 48-hour (3.4±2.0 vs. 2.2±1.8; P = 0.042) intervals. At admission, overall mean serum zinc level was 63.8 mg/dL and 57.1% of children had zinc deficiency with no difference in prevalence between groups. PRAM scores did not differ between children with low and normal zinc status. In conclusion, zinc supplementation as the adjuvant therapy to the standard treatment during asthma exacerbation resulted in rapid lessening of severity.

Psoriatic inflammation enhances allergic airway inflammation through IL-23/STAT3 signaling in a murine model

Psoriasis is an autoimmune inflammatory skin disease characterized by activated IL-23/STAT3/Th17 axis. Recently psoriatic inflammation has been shown to be associated with asthma. However, no study has previously explored how psoriatic inflammation affects airway inflammation. Therefore, this study investigated the effect of imiquimod (IMQ)-induced psoriatic inflammation on cockroach extract (CE)-induced airway inflammation in murine models. Mice were subjected to topical and intranasal administration of IMQ and CE to develop psoriatic and airway inflammation respectively. Various analyses in lung/spleen related to inflammation, Th17/Th2/Th1 cell immune responses, and their signature cytokines/transcription factors were carried out. Psoriatic inflammation in allergic mice was associated with increased airway inflammation with concurrent increase in Th2/Th17 cells/signature cytokines/transcription factors. Splenic CD4+ T and CD11c+ dendritic cells in psoriatic mice had increased STAT3/RORC and IL-23 mRNA expression respectively. This led us to explore the effect of systemic IL-23/STAT3 signaling on airway inflammation. Topical application of STA-21, a small molecule STAT3 inhibitor significantly reduced airway inflammation in allergic mice having psoriatic inflammation. On the other hand, adoptive transfer of IL-23-treated splenic CD4+ T cells from allergic mice into naive recipient mice produced mixed neutrophilic/eosinophilic airway inflammation similar to allergic mice with psoriatic inflammation. Our data suggest that systemic IL-23/STAT3 axis is responsible for enhanced airway inflammation during psoriasis. The current study also suggests that only anti-asthma therapy may not be sufficient to alleviate airway inflammatory burden in asthmatics with psoriasis.

Tiron ameliorates oxidative stress and inflammation in a murine model of airway remodeling

Airway remodeling includes lung structural changes that have a role in the irreversibility of pulmonary dysfunction shown in chronic bronchial asthmatics. The current experiment investigated the effect of the mitochondrial antioxidant, tiron in comparison with dexamethasone (DEXA) on airway remodeling in chronic asthma. Sensitized BALB/c mice were challenged with ovalbumin (OVA) aerosol for 8weeks, OVA sensitized-challenged mice were treated with either DEXA or tiron, respectively. After that, lung tissue and bronchoaveolar lavage fluid (BALF) were used for measurement of different biological markers. Lungs were examined for histopathological changes and immunohistochemistry. Upon comparing with vehicle treated animals, trion or DEXA treatment significantly reduced eosinophils, lymphocytes, neutrophils and macrophages count in the BALF. Both drugs significantly alleviated chronic OVA-induced oxidative stress as illustrated by decreased pulmonary malondialdenhyde (MDA) and increased glutathione (GSH) and superoxide dismutase (SOD) levels. Asthmatic mice exhibited elevated levels of NOx, IL-13 and TGF-β1 that were reduced by DEXA and tiron. Histopathological changes and increased immunoreactivity of nuclear factor-Kappa B (NF-κ B) in OVA-challenged mice were minimized by tiron and DEXA treatment. In conclusion, in this model of chronic asthma DEXA and tiron ameliorated airway remodeling and inflammation in experimental chronic asthma with no difference between the effect of tiron and DEXA. Tiron has a potential role as adjuvant treatment in chronic asthma.

Airway oxidative stress causes vascular and hepatic inflammation via upregulation of IL-17A in a murine model of allergic asthma

Oxidants are generated in asthmatic airways due to infiltration of inflammatory leukocytes and resident cells in the lung. Reactive oxygen species (ROS) such as hydrogen peroxide and superoxide radical may leak into systemic circulation when generated in uncontrolled manner and may impact vasculature. Our previous studies have shown an association between airway inflammation and systemic inflammation; however so far none has investigated the impact of airway oxidative inflammation on hepatic oxidative stress and Th1/Th2/Th17 cytokine markers in liver/vasculature in a murine model of asthma. Therefore, this study investigated the contribution of oxidative stress encountered in asthmatic airways in modulation of systemic/hepatic Th1/Th2/Th17 cytokines balance and hepatic oxidative stress. Mice were sensitized intraperitoneally with cockroach extract (CE) in the presence of aluminum hydroxide followed by several intranasal (i.n.) challenges with CE. Mice were then assessed for systemic/hepatic inflammation through assessment of Th1/Th2/Th17 cytokines and oxidative stress (iNOS, protein nitrotyrosine, lipid peroxides and myeloperoxidase activity). Challenge with CE led to increased Th2/Th17 cytokines in blood/liver and hepatic oxidative stress. However, only Th17 related pro-inflammatory markers were upregulated by hydrogen peroxide (H2O2) inhalation in vasculature and liver, whereas antioxidant treatment, N-acetyl cysteine (NAC) downregulated them. Hepatic oxidative stress was also upregulated by H2O2 inhalation, whereas NAC attenuated it. Therefore, our study shows that airway oxidative inflammation may contribute to systemic inflammation through upregulation of Th17 immune responses in blood/liver and hepatic oxidative stress. This might predispose these patients to increased risk for the development of cardiovascular disorders.

TLR-7 agonist attenuates airway reactivity and inflammation through Nrf2-mediated antioxidant protection in a murine model of allergic asthma

Toll-like receptors (TLRs) through innate immune system recognize pathogen associated molecular patterns and play an important role in host defense against bacteria, fungi and viruses. TLR-7 is responsible for sensing single stranded nucleic acids of viruses but its activation has been shown to be protective in mouse models of asthma. The NADPH oxidase (NOX) enzymes family mainly produces reactive oxygen species (ROS) in the lung and is involved in regulation of airway inflammation in response to TLRs activation. However, NOX-4 mediated signaling in response to TLR-7 activation in a mouse model of allergic asthma has not been explored previously. Therefore, this study investigated the role TLR-7 activation and downstream oxidant-antioxidant signaling in a murine model of asthma. Mice were sensitized with ovalbumin (OVA) intraperitoneally and treated with TLR-7 agonist, resiquimod (RSQ) intranasally before each OVA challenge from days 14 to 16. Mice were then assessed for airway reactivity, inflammation, and NOX-4 and nuclear factor E2-related factor 2 (Nrf2) related signaling [inducible nitric oxide synthase (iNOS), nitrotyrosine, lipid peroxides and copper/zinc superoxide dismutase (Cu/Zn SOD)]. Treatment with RSQ reduced allergen induced airway reactivity and inflammation. This was paralleled by a decrease in ROS which was due to induction of Nrf2 and Cu/Zn SOD in RSQ treated group. Inhibition of MyD88 reversed RSQ-mediated protective effects on airway reactivity/inflammation due to reduction in Nrf2 signaling. SOD inhibition produced effects similar to MyD88 inhibition. The current study suggests that TLR-7 agonist is beneficial and may be developed into a therapeutic option in allergic asthma.

Recombinant human deoxyribonuclease attenuates oxidative stress in a model of eosinophilic pulmonary response in mice

The inflammatory cells infiltrating the airways produce several mediators, such as reactive oxygen species (ROS). ROS and the oxidant-antioxidant imbalance might play an important role in the modulation of airways inflammation. In order to avoid the undesirable effects of ROS, various endogenous antioxidant strategies have evolved, incorporating both enzymatic and non-enzymatic mechanisms. Recombinant human deoxyribonuclease (rhDNase) in clinical studies demonstrated a reduction in sputum viscosity, cleaving extracellular DNA in the airways, and facilitating mucus clearance, but an antioxidant effect was not studied so far. Therefore, we evaluated whether the administration of rhDNase improves oxidative stress in a murine model of asthma. Mice were sensitized by two subcutaneous injections of ovalbumin (OVA), on days 0 and 7, followed by three lung challenges with OVA on days 14, 15, and 16. On days 15 and 16, after 2 h of the challenge with OVA, mice received 1 mg/mL of rhDNase in the lungs. Bronchoalveolar lavage fluid and lung tissue were obtained on day 17, for inflammatory and oxidative stress analysis. We showed that rhDNase did not alter the population of inflammatory cells, such as eosinophil cells, in OVA-treated rhDNase group but significantly improved oxidative stress in lung tissue, by decreasing oxygen reactive species and increasing superoxide dismutase/catalase ratio, glutathione peroxidase activity, and thiol content. Our data provide the first evidence that rhDNase decreases some measures of oxidative stress and antioxidant status in a murine model of asthma, with a potential antioxidant effect to be further studied in human asthma.

Evaluation of multidrug resistance-1 gene C>T polymorphism frequency in patients with asthma

OBJECTIVES

Asthma is a chronic inflammatory lung disease characterized by bronchial hyperresponsiveness and airflow obstruction. Genetic and oxidative stress factors, in addition to pulmonary and systemic inflammatory processes, play a pivotal role in the pathogenesis of asthma. The products of the multidrug resistance-1 gene protect lung tissue from oxidative stress. Here, we aimed to evaluate the association between the multidrug resistance-1 gene C>T polymorphism and asthma with regard to oxidative stress-related parameters of asthmatic patients.

METHODS

Forty-five patients with asthma and 27 healthy age-matched controls were included in this study. Blood samples were collected in tubes with ethylenediaminetetraacetic acid. DNA was extracted from the blood samples. The multidrug resistance-1 gene polymorphism was detected by polymerase chain reaction and a subsequent enzyme digestion technique. The serum levels of total oxidant status and total antioxidant status were determined by the colorimetric measurement method.

RESULTS

The heterozygous polymorphic genotype was the most frequent in both groups. A significant difference in the multidrug resistance-1 genotype frequencies between groups indicated an association of asthma with the TT genotype. A significant difference between groups was found for wild type homozygous participants and carriers of polymorphic allele participants. The frequency of the T allele was significantly higher in asthmatic patients. The increase in the oxidative stress index parameter was significant in the asthma group compared with the control group.

CONCLUSIONS

The multidrug resistance-1 gene C/T polymorphism may be an underlying genetic risk factor for the development of asthma via oxidant-antioxidant imbalance, leading to increased oxidative stress.

Proteinase activated receptor-2-mediated dual oxidase-2 up-regulation is involved in enhanced airway reactivity and inflammation in a mouse model of allergic asthma

Airway epithelial cells (AECs) express a variety of receptors, which sense danger signals from various aeroallergens/pathogens being inhaled constantly. Proteinase-activated receptor 2 (PAR-2) is one such receptor and is activated by cockroach allergens, which have intrinsic serine proteinase activity. Recently, dual oxidases (DUOX), especially DUOX-2, have been shown to be involved in airway inflammation in response to Toll-like receptor activation. However, the association between PAR-2 and DUOX-2 has not been explored in airways of allergic mice. Therefore, this study investigated the contribution of DUOX-2/reactive oxygen species (ROS) signalling in airway reactivity and inflammation after PAR-2 activation. Mice were sensitized intraperitoneally with intact cockroach allergen extract (CE) in the presence of aluminium hydroxide followed by intranasal challenge with CE. Mice were then assessed for airway reactivity, inflammation, oxidative stress (DUOX-2, ROS, inducible nitric oxide synthase, nitrite, nitrotyrosine and protein carbonyls) and apoptosis (Bax, Bcl-2, caspase-3). Challenge with CE led to up-regulation of DUOX-2 and ROS in AECs with concomitant increases in airway reactivity/inflammation and parameters of oxidative stress, and apoptosis. All of these changes were significantly inhibited by intranasal administration of ENMD-1068, a small molecule antagonist of PAR-2 in allergic mice. Administration of diphenyliodonium to allergic mice also led to improvement of allergic airway responses via inhibition of the DUOX-2/ROS pathway; however, these effects were less pronounced than PAR-2 antagonism. The current study suggests that PAR-2 activation leads to up-regulation of the DUOX-2/ROS pathway in AECs, which is involved in regulation of airway reactivity and inflammation via oxidative stress and apoptosis.