Airway Oxidative Stress Research Articles

Elevated Ambient PM10 Levels Affecting Respiratory Health of Schoolchildren in Chiang Mai, Thailand

The health effects from exposure to particulate air pollution during the dry season (February-March) in northern Thailand, a longstanding problem, have become particularly acute since 2007. Although several studies have reported the effect of ambient PM 10 levels on airway oxidative stress and pulmonary function among respiratory disease patients, few studies have focused on healthy children, especially in Thailand. We conducted a prospective follow-up study to assess the respiratory health among schoolchildren exposed to different levels of ambient PM 10 by comparing exhaled malondialdehyde (MDA) concentrations and pulmonary function indices. Exhaled breath condensate (EBC) samples were obtained from individual participants. MDA in EBC has been proposed as a biomarker of airway oxidative stress. The participants were 54 healthy schoolchildren with median (min-max) age of 11 (10-12) years old from a pri- mary school in Chiang Mai City, Thailand. Questionnaires and EBC samples were collected twice, in the rainy season (July 2011, low PM 10 level) and the dry season (March 2012, high PM 10 level). It required about 10 minutes to collect EBC samples of 1-3 mL from individual participants, using an EBC-collect- ing apparatus that was modified specifically for this research from a standard hospital-use apparatus. MDA concentration in EBC was analyzed using HPLC- UV detection. Trained public health personnel performed the pulmonary function tests. The median of exhaled MDA concentrations in the rainy and dry seasons was 0.17 and 0.22 µM, respectively. Mean ± SD of forced expiratory volume in one-second/forced vital capacity ratios (FEV 1 /FVC) in the rainy and dry seasons was 94.6 ± 4.4 and 91.3 ± 4.7 percent predicted, respectively. Exhaled MDA concentration significantly increased and the FEV 1 /FVC ratio significantly decreased in the dry season (p<0.05). This results shows that elevated ambient

Oxidative Stress in Airway Diseases

Airway oxidative stress is broadly defined as an imbalance between prooxidative and antioxidative processes in the airway. Given its direct exposure to the environment, the lung has several mechanisms to prevent an excessive degree of oxidative stress. Both enzymatic and nonenzymatic systems can buffer a wide range of reactive oxidative species and other compounds with oxidative potential. In diseases like asthma and chronic obstructive lung disease, airway oxidative stress can occur from a number of sources, including greater exposure to environmental prooxidants, airway infiltration of inflammatory cells, metabolic deregulation, and reduced levels of antioxidants. Airway oxidative stress has been associated with worse disease severity, reduced lung function, and epigenetic changes that can diminish response to steroids. Although oxidative stress has been linked to a wide range of adverse biological effects, it has also been associated with adaptive responses and with resolution of inflammation. Therefore, more than being an imbalance with a predictable threshold after which disease or injury ensues, oxidative stress is a dynamic and continuous process. This might explain why supplementing antioxidants has largely failed to improve diseases such as asthma and chronic obstructive pulmonary disease. However, the therapeutic potential of antioxidants could be greatly improved by taking an approach that considers individual and environmental risk factors, instead of treating oxidative airway stress broadly.

Serum concentrations of club cell secretory protein (Clara) and cancer mortality in adults: a population-based, prospective cohort study

Club cell secretory protein (Clara) (CC16) is produced mainly by bronchiolar club cells and has been shown to have protective effects against airway inflammation and oxidative stress from cigarette smoking and related carcinogens. The goal of this study was to establish whether serum CC16 concentrations predict all-cause and cancer-specific mortality in adults. We used data from the population-based Tucson Epidemiological Study of Airway Obstructive Diseases (TESAOD), a prospective cohort study of respiratory health initiated in Tucson, AZ, USA, in 1972, that recruited a multistage stratified cluster sample of non-Hispanic white households. We measured serum CC16 concentrations in cryopreserved serum samples and reviewed vital status up to Jan 1, 2011, through contact with next of kin, collection of death certificates, and searches of the National Death Index. Our primary analysis was the relation of baseline serum CC16 to all-cause mortality or cause-specific mortality risk, analysed by adjusted Cox proportional hazards models. 1086 TESAOD participants aged 21-70 years at enrolment were eligible for inclusion. Of these, 653 (60%) had died by 2011, and cause of death was ascertained for 649 (99%). When adjusted for sex, age, education, body-mass index, smoking and pack-years, and baseline levels of lung function, serum CC16 concentrations at baseline were inversely associated with mortality risk over the study follow-up. Mortality risk increased for each 1-SD decrease in CC16 (adjusted hazard ratio [HR] 1·16 [95% CI 1·06-1·26]; p=0·0007). For cause-specific mortality, each 1-SD decrease in serum CC16 was associated with an increased risk of dying of cancer (adjusted HR 1·41 [1·19-1·67]; p<0·0001). In the subset of smokers, the corresponding adjusted HR for mortality by lung cancer was 1·52 (1·14-2·03; p=0·004). Serum CC16 concentrations can predict mortality risk in the general adult population. The excess risk associated with lower CC16 concentrations is predominantly driven by cancer, particularly lung cancer. National Heart, Lung, and Blood Institute.

Thioredoxin-1 Protects against Neutrophilic Inflammation and Emphysema Progression in a Mouse Model of Chronic Obstructive Pulmonary Disease Exacerbation

BackgroundExacerbations of chronic obstructive pulmonary disease (COPD) are characterized by acute enhancement of airway neutrophilic inflammation under oxidative stress and can be involved in emphysema progression. However, pharmacotherapy against the neutrophilic inflammation and emphysema progression associated with exacerbation has not been established. Thioredoxin-1 has anti-oxidative and anti-inflammatory properties and it can ameliorate neutrophilic inflammation through anti-chemotactic effects and prevent cigarette smoke (CS)-induced emphysema. We aimed to determine whether thioredoxin-1 can suppress neutrophilic inflammation and emphysema progression in a mouse model of COPD exacerbation and if so, to reveal the underlying mechanisms.ResultsMice were exposed to CS and then challenged with polyinosine-polycytidylic acid [poly(I:C)], an agonist for virus-induced innate immunity. Airway neutrophilic inflammation, oxidative stress and lung apoptosis were enhanced in smoke-sensitive C57Bl/6, but not in smoke-resistant NZW mice. Exposure to CS and poly(I:C) challenge accelerated emphysema progression in C57Bl/6 mice. Thioredoxin-1 suppressed neutrophilic inflammation and emphysema progression. Poly(I:C) caused early neutrophilic inflammation through keratinocyte-derived chemokine and granulocyte-macrophage colony-stimulating factor (GM-CSF) release in the lung exposed to CS. Late neutrophilic inflammation was caused by persistent GM-CSF release, which thioredoxin-1 ameliorated. Thioredoxin-1 enhanced pulmonary mRNA expression of MAP kinase phosphatase 1 (MKP-1), and the suppressive effects of thioredoxin-1 on prolonged GM-CSF release and late neutrophilic inflammation disappeared by inhibiting MKP-1.ConclusionUsing a mouse model of COPD exacerbation, we demonstrated that thioredoxin-1 ameliorated neutrophilic inflammation by suppressing GM-CSF release, which prevented emphysema progression. Our findings deepen understanding of the mechanisms underlying the regulation of neutrophilic inflammation by thioredoxin-1 and indicate that thioredoxin-1 could have potential as a drug to counteract COPD exacerbation.

Pepsin levels and oxidative stress markers in exhaled breath condensate of patients with gastroesophageal reflux disease

AimTo evaluate the pepsin and oxidative stress markers in exhaled breath condensate (EBC) in patients with gastroesophageal reflux disease (GERD). Patients and MethodPatients with a presumptive diagnosis of GERD with recurrent respiratory and gastrointestinal problems aged between 2 and 14years were included in the study. All patients underwent pH monitoring. Patients with a reflux index (RI) ≥4 were assessed as the reflux group, and those with an RO <4 were assessed as the non-reflux group. Pepsin levels and oxidative stress markers [NO metabolites (NOX) and total sulphydrile (TSH) levels] were measured in the EBC. ResultsThere were 24 patients in the reflux group [RI 17.6 (6.6–46.4)] [median, interquartile range] and 23 in the non-reflux group [RI 0.8 (0.5–1.9) (p<0.001). Pepsin levels in the EBC were below the level of detection. The median levels of NOx in the EBC of children with reflux [13.7μmol/L (7.3–24.5)] were lower in than non-reflux group [21.0μmol/L (14.0–25.2)] (p=0.034). There was a negative correlation between reflux index and NOX levels in EBC (rs: −0.331, p=0.023). In contrast, there was no difference in TSH levels between the reflux and non-reflux groups [37.4μmol/L (30.2–44.6) vs 40.1μmol/L (37.4–44.9), respectively, (p>0.05)]. ConclusionDecreased levels of NOX in patients with GER disease suggest increased oxidative stress in airways of these patients.

Effects of long‐term azithromycin therapy on airway oxidative stress markers in non‐cystic fibrosis bronchiectasis

To explore the effect of long-term therapy with azithromycin in regards to airway oxidative stress markers in exhaled breath condensate (EBC) of adult patients with stable non-cystic fibrosis (CF) bronchiectasis. Open-label prospective study of 30 patients randomized to azithromycin 250 mg three times per week during 3 months (16 patients) or control (14 patients). Primary outcome were changes in nitric oxide, 8-isoprostane, pH, nitrites and nitrates in EBC. Secondary outcomes were changes in exacerbation rates, dyspnoea (Borg scale), sputum volume (cc), sputum colour (15-point scale), bacterial infection, health-related quality of life (St George's Respiratory Questionnaire), lung function and radiological extension. Azithromycin produced a significant decrease in sputum volume (8.9 (1.8) mL vs 2.1 (3.4) mL) and number of exacerbations (0.1 (0.6) vs 1.2 (0.9)). Dyspnoea (0.4 (0.1) vs 0.1 (0.2)) and health-related quality of life also improved after therapy. However, oxidative stress markers in EBC, systemic inflammatory markers as well as functional respiratory tests did not differ from the control group after therapy. A post-hoc analysis comparing patients infected or not with Pseudomonas aeruginosa revealed that these effects were more pronounced in infected patients. In this subgroup, treatment was followed by a significant reduction in sputum volume, number of exacerbations, dyspnoea and St George's Respiratory Questionnaire total score. Of all airway oxidative stress markers, only nitrates in EBC were reduced after therapy. Long-term azythromicin treatment has some clinical benefits in patients with non-CF stable bronchiectasis, but it does not affect airway oxidative stress markers.

Exposure during short-lived air pollution events is more predictive of airway oxidative stress than mean concentration

Exposure during short-lived air pollution events is more predictive of airway oxidative stress than mean concentration

Chronic Alcohol Ingestion Primes the Lung for Bleomycin-Induced Fibrosis in Mice

Alcohol abuse increases the risk for acute lung injury (ALI). In both experimental models and in clinical studies, chronic alcohol ingestion causes airway oxidative stress and glutathione depletion and increases the expression of transforming growth factor beta-1 (TGFβ1), a potent inducer of fibrosis, in the lung. Therefore, we hypothesized that alcohol ingestion could promote aberrant fibrosis following experimental ALI and that treatment with the glutathione precursor s-adenosylmethionine (SAMe) could mitigate these effects. Three-month-old C57BL/6 mice were fed standard chow±alcohol (20% v/v) in their drinking water for 8weeks and ±SAMe (4% w/v) during the last 4weeks. ALI was induced by intratracheal instillation of bleomycin (2.5 units/kg), and lungs were assessed histologically at 7 and 14days for fibrosis and at 14days for the expression of extracellular matrix proteins and TGFβ1. Alcohol ingestion had no apparent effect on lung inflammation at 7days, but at 14days after bleomycin treatment, it increased lung tissue collagen deposition, hydroxyproline content, and the release of activated TGFβ1 into the airway. In contrast, SAMe supplementation completely mitigated alcohol-induced priming of these aberrant fibrotic changes through decreased TGFβ1 expression in the lung. In parallel, SAMe decreased alcohol-induced TGFβ1 and Smad3 mRNA expressions by lung fibroblasts in vitro. These new experimental findings demonstrate that chronic alcohol ingestion renders the experimental mouse lung susceptible to fibrosis following bleomycin-induced ALI, and that these effects are likely driven by alcohol-mediated oxidative stress and its induction and activation of TGFβ1.

Bronchopulmonary dysplasia: The earliest and perhaps the longest lasting obstructive lung disease in humans

Bronchopulmonary dysplasia (BPD) is one of the most important sequelae of premature birth and the most common form of chronic lung disease of infancy. From a clinical standpoint BPD subjects are characterized by recurrent respiratory symptoms, which are very frequent during the first years of life and, although becoming less severe as children grow up, they remain more common than in term-born controls throughout childhood, adolescence and into adulthood. From a functional point of view BPD subjects show a significant airflow limitation that persists during adolescence and adulthood and they may experience an earlier and steeper decline in lung function during adulthood. Interestingly, patients born prematurely but not developing BPD usually fare better, but they too have airflow limitations during childhood and later on, suggesting that also prematurity per se has life-long detrimental effects on pulmonary function. For the time being, little is known about the presence and nature of pathological mechanisms underlying the clinical and functional picture presented by BPD survivors. Nonetheless, recent data suggest the presence of persistent neutrophilic airway inflammation and oxidative stress and it has been suggested that BPD may be sustained in the long term by inflammatory pathogenic mechanisms similar to those underlying COPD. This hypothesis is intriguing but more pathological data are needed. A better understanding of these pathogenetic mechanisms, in fact, may be able to orient the development of novel targeted therapies or prevention strategies to improve the overall respiratory health of BPD patients.

Nose-only water-pipe smoking effects on airway resistance, inflammation, and oxidative stress in mice

Water-pipe smoking (WPS) is a common practice in the Middle East and is now gaining popularity in Europe and the United States. However, there is a limited number of studies on the respiratory effects of WPS. More specifically, the underlying pulmonary pathophysiological mechanisms related to WPS exposure are not understood. Presently, we assessed the respiratory effects of nose-only exposure to mainstream WPS generated by commercially available honey flavored "moasel" tobacco. The duration of the session was 30 min/day and 5 days/wk for 1 mo. Control mice were exposed to air only. Here, we measured in BALB/c mice the airway resistance using forced-oscillation technique. Lung inflammation was assessed histopathologically and by biochemical analysis of bronchoalveolar lavage (BAL) fluid, and oxidative stress was evaluated biochemically by measuring lipid peroxidation, reduced glutathione and several antioxidant enzymes. Pulmonary inflammation assessment showed an increase in neutrophil and lymphocyte numbers. Likewise, airway resistance was significantly increased in the WPS group compared with controls. Tumor necrosis factor α and interleukin 6 concentrations were significantly increased in BAL fluid. Lipid peroxidation in lung tissue was significantly increased whereas the level and activity of antioxidants including reduced glutathione, glutathione S transferase, and superoxide dismutase were all significantly decreased following WPS exposure, indicating the occurrence of oxidative stress. Moreover, carboxyhemoglobin levels were significantly increased in the WPS group. We conclude that 1-mo nose-only exposure to WPS significantly increased airway resistance, inflammation, and oxidative stress. Our results provide a mechanistic explanation for the limited clinical studies that reported the detrimental respiratory effects of WPS.

Long-Term Continuous Positive Airway Pressure Therapy Normalizes High Exhaled Nitric Oxide Levels in Obstructive Sleep Apnea

Upper airway inflammation and oxidative stress have been implicated in the pathogenesis of obstructive sleep apnea (OSA) and may be linked to cardiovascular consequences. We prospectively examined fraction of exhaled nitric oxide (FENO), a surrogate marker of upper airway inflammation using a portable nitric oxide analyzer (NIOX MINO). In consecutive adult nonsmokers with suspected OSA, FENO was measured immediately before and after polysomnographic studies, and within 1-3 months following continuous positive airway pressure (CPAP) therapy. FENO levels were increased in the 75 patients with OSA compared to the 29 controls, both before sleep (13.4 ± 6.5 ppb vs. 6.5 ± 3.5; p < 0.001) and after sleep (19.0 ± 7.7 ppb vs. 6.9 ± 3.7; p < 0.001). Furthermore, in patients with OSA, FENO levels were significantly higher post-sleep than pre-sleep (19.0 ± 7.7 ppb vs. 13.4 ± 6.5; p < 0.001), while there was no significant overnight change in patients without OSA. The rise in FENO correlated with the apnea-hypopnea index (r = 0.65, p < 0.001), nadir oxygen saturation (r = 0.54, p < 0.001), and arousal index (r = 0.52, p < 0.001). Thirty-seven of these patients underwent CPAP titration and treatment. Successful titration was associated with a lower overnight increase in FENO (7.2 ± 3.3 vs. 11.0 ± 4.3, p = 0.02). FENO levels declined after 1-3 months of CPAP therapy (11.7 ± 4.4 ppb, p < 0.001). FENO levels are elevated in OSA, correlate with severity, and decrease after positive pressure therapy. This study supports the role of upper airway inflammation in OSA pathogenesis and a possible role for FENO in monitoring CPAP therapy.

Airway inflammation and oxidative potential of air pollutant particles in a pediatric asthma panel

Airborne particulate matter (PM) components from fossil fuel combustion can induce oxidative stress initiated by reactive oxygen species (ROS). Reported associations between worsening asthma and PM2.5 mass could be related to PM oxidative potential to induce airway oxidative stress and inflammation (hallmarks of asthma pathology). We followed 45 schoolchildren with persistent asthma in their southern California homes daily over 10 days with offline fractional exhaled nitric oxide (FENO), a biomarker of airway inflammation. Ambient exposures included daily average PM2.5, PM2.5 elemental and organic carbon (EC, OC), NO2, O3, and endotoxin. We assessed PM2.5 oxidative potential using both an abiotic and an in vitro bioassay on aqueous extracts of daily particle filters: (1) dithiothreitol (DTT) assay (abiotic), representing chemically produced ROS; and (2) ROS generated intracellularly in a rat alveolar macrophage model using the fluorescent probe 2'7'-dicholorohidroflourescin diacetate. We analyzed relations of FENO to air pollutants in mixed linear regression models. FENO was significantly positively associated with lag 1-day and 2-day averages of traffic-related markers (EC, OC, and NO2), DTT and macrophage ROS, but not PM2.5 mass. DTT associations were nearly twice as strong as other exposures per interquartile range: median FENO increased 8.7-9.9% per 0.43 nmole/min/m(3) DTT. Findings suggest that future research in oxidative stress-related illnesses such as asthma and PM exposure would benefit from assessments of PM oxidative potential and composition.

Glutathione S‐transferase P1 Ile105Val polymorphism modulates allergen‐induced airway inflammation in human atopic asthmatics in vivo

Glutathione S-transferase P1 is a Phase II cytoprotective and detoxifying enzyme that is widely expressed in human airways. The glutathione S-transferase P1 Ile105Val polymorphism has been linked with atopic disorders and asthma. Yet, little remains known about the regulation of allergic inflammation by glutathione S-transferase P1 in human asthmatics. To establish the effect of the glutathione S-transferase P1 Ile105Val polymorphism on allergen-induced airway inflammation and oxidant stress, and non-specific bronchial hyperresponsiveness to methacholine and reactivity to specific allergen in mild human atopic asthmatics in vivo. Five Val(105)/Val(105) , twelve Val(105)/Ile(105) and twenty Ile(105)/Ile(105) mild atopic asthmatics underwent methacholine challenge, inhaled allergen challenge and endobronchial allergen provocation through a bronchoscope. A panel of inflammatory cytokines and chemokines, F2 -isoprostanes and isofuranes, markers of oxidative stress, thromboxane B2 and immunoglobulin E were measured in bronchoalveolar lavage fluid at baseline and 24 h after allergen instillation. Asthmatics with glutathione S-transferase P1 Val(105)/Val(105) compared with asthmatics with the glutathione S-transferase P1 Val(105)/Ile(105) and Ile(105)/Ile(105) had greater generation of acute phase cytokines (TNF-α, IL-6, CXCL8), IL-12, CCL11, thromboxane B2 and immunoglobulin E at 24 h after local allergen challenge. The GSTP1 genotype had no effect on airway hyperresponsiveness to methacholine and the reactivity to specific allergen. The glutathione S-transferase P1 Ile105Val polymorphism markedly modifies allergen-provoked airway inflammation in atopic asthmatics in vivo. Modulation of the biochemical milieu in response to allergen provides a mechanistic explanation for regulatory effects of glutathione S-transferase P1 polymorphism on airway pathophysiology, and may guide improvement of future therapeutic methods in human atopic asthmatics. These findings must me confirmed in a larger study population of asthmatics with various ethnicities.

Airway oxidative stress in chronic cough

BackgroundThe mechanisms of chronic cough are unclear. Many reactive oxygen species affect airway sensory C-fibres which are capable to induce cough. Several chronic lung diseases are characterised by cough and oxidative stress. In asthma, an association between the cough severity and airway oxidative stress has been demonstrated. The present study was conducted to investigate whether airway oxidative stress is associated with chronic cough in subjects without chronic lung diseases.MethodsExhaled breath condensate samples were obtained in 43 non-smoking patients with chronic cough and 15 healthy subjects. Exclusion criteria included a doctor’s diagnosis of any lung disorders and any abnormality in lung x-ray. The concentration of 8-isoprostane was measured. In addition, the patients filled in Leicester Cough Questionnaire and underwent hypertonic saline cough provocation test, spirometry, ambulatory peak flow monitoring, nitric oxide measurement, and histamine airway challenge. In a subgroup of patients the measurements were repeated during 12 weeks’ treatment with inhaled budesonide, 800 ug/day.ResultsThe 8-isoprostane concentrations were higher in the cough patients than in the healthy subjects (24.6 ± 1.2 pg/ml vs. 10.1 ± 1.7 pg/ml, p = 0.045). The 8-isoprostane concentration was associated with the Leicester Cough Questionnaire total score (p = 0.044) but not with the cough sensitivity to saline or other tests. Budesonide treatment did not affect the 8-isoprostane concentrations.ConclusionsChronic cough seems to be associated with airway oxidative stress in subjects with chronic cough but without chronic lung diseases. This finding may help to develop novel antitussive drugs.Trial registrationThe study was registered in ClinicalTrials.gov database (KUH5801112), identifier NCT00859274.

Effect of high-dose N-acetylcysteine on airway geometry, inflammation, and oxidative stress in COPD patients

BackgroundPrevious studies have demonstrated the potential beneficial effect of N-acetylcysteine (NAC) in chronic obstructive pulmonary disease (COPD). However, the required dose and responder phenotype remain unclear. The current study investigated the effect of high-dose NAC on airway geometry, inflammation, and oxidative stress in COPD patients. Novel functional respiratory imaging methods combining multislice computed tomography images and computer-based flow simulations were used with high sensitivity for detecting changes induced by the therapy.MethodsTwelve patients with Global Initiative for Chronic Obstructive Lung Disease stage II COPD were randomized to receive NAC 1800 mg or placebo daily for 3 months and were then crossed over to the alternative treatment for a further 3 months.ResultsSignificant correlations were found between image-based resistance values and glutathione levels after treatment with NAC (P = 0.011) and glutathione peroxidase at baseline (P = 0.036). Image-based resistance values appeared to be a good predictor for glutathione peroxidase levels after NAC (P = 0.02), changes in glutathione peroxidase levels (P = 0.035), and reduction in lobar functional residual capacity levels (P = 0.00084). In the limited set of responders to NAC therapy, the changes in airway resistance were in the same order as changes induced by budesonide/formoterol.ConclusionA combination of glutathione, glutathione peroxidase, and imaging parameters could potentially be used to phenotype COPD patients who would benefit from addition of NAC to their current therapy. The findings of this small pilot study need to be confirmed in a larger pivotal trial.

Reducing Agents Decrease the Oxidative Burst and Improve Clinical Outcomes in COPD Patients: A Randomised Controlled Trial on the Effects of Sulphurous Thermal Water Inhalation

Background. Inhalation of thermal water with antioxidant properties is empirically used for COPD. Aims. To evaluate the effects of sulphurous thermal water (reducing agents) on airway oxidant stress and clinical outcomes in COPD. Methods. Forty moderate-to-severe COPD patients were randomly assigned to receive 12-day inhalation with sulphurous thermal water or isotonic saline. Patients were assessed for superoxide anion (O2 −) production in the exhaled breath condensate and clinical outcomes at recruitment, the day after the conclusion of the 12-day inhalation treatment, and one month after the end of the inhalation treatment. Results. Inhalation of reducing agents resulted in a significant reduction of O2 − production in exhaled breath condensate of COPD patients at the end of the inhalatory treatment and at followup compared to baseline. A significant improvement in the COPD assessment test (CAT) questionnaire was shown one month after the end of the inhalatory treatment only in patients receiving sulphurous water. Conclusion. Thermal water inhalation produced an in vivo antioxidant effect and improvement in health status in COPD patients. Larger studies are required in order to evaluate whether inhalation of thermal water is able to modify relevant clinical outcomes of the disease (the study was registered at clinicaltrial.gov—identifier: NCT01664767).

Evaluation of cytotoxic, genotoxic and inflammatory responses of nanoparticles from photocopiers in three human cell lines

BackgroundPhotocopiers emit nanoparticles with complex chemical composition. Short-term exposures to modest nanoparticle concentrations triggered upper airway inflammation and oxidative stress in healthy human volunteers in a recent study. To further understand the toxicological properties of copier-emitted nanoparticles, we studied in-vitro their ability to induce cytotoxicity, pro-inflammatory cytokine release, DNA damage, and apoptosis in relevant human cell lines.MethodsThree cell types were used: THP-1, primary human nasal- and small airway epithelial cells. Following collection in a large volume photocopy center, nanoparticles were extracted, dispersed and characterized in the cell culture medium. Cells were doped at 30, 100 and 300 μg/mL administered doses for up to 24 hrs. Estimated dose delivered to cells, was ~10% and 22% of the administered dose at 6 and 24 hrs, respectively. Gene expression analysis of key biomarkers was performed using real time quantitative PCR (RT-qPCR) in THP-1 cells at 5 μg nanoparticles/mL for 6-hr exposure for confirmation purposes.ResultsMultiple cytokines, GM-CSF, IL-1β, IL-6, IL-8, IFNγ, MCP-1, TNF-α and VEGF, were significantly elevated in THP-1 cells in a dose-dependent manner. Gene expression analysis confirmed up-regulation of the TNF-α gene in THP-1 cells, consistent with cytokine findings. In both primary epithelial cells, cytokines IL-8, VEGF, EGF, IL-1α, TNF-α, IL-6 and GM-CSF were significantly elevated. Apoptosis was induced in all cell lines in a dose-dependent manner, consistent with the significant up-regulation of key apoptosis-regulating genes P53 and Casp8 in THP-1 cells. No significant DNA damage was found at any concentration with the comet assay. Up-regulation of key DNA damage and repair genes, Ku70 and Rad51, were also observed in THP-1 cells, albeit not statistically significant. Significant up-regulation of the key gene HO1 for oxidative stress, implicates oxidative stress induced by nanoparticles.ConclusionsCopier-emitted nanoparticles induced the release of pro-inflammatory cytokines, apoptosis and modest cytotoxicity but no DNA damage in all three-human cell lines. Taken together with gene expression data in THP-1 cells, we conclude that these nanoparticles are directly responsible for inflammation observed in human volunteers. Further toxicological evaluations of these nanoparticles, including across different toner formulations, are warranted.

Supplementation of antioxidants glutathione and α-lipoic acid attenuates oxidative stress and Th2 response in allergic airway inflammation

Background: Inflammatory lung diseases such as asthma are characterized by chronic inflammation, oxidative stress, and altered antioxidant defenses. Increased levels of reactive oxygen species (ROS) contribute to asthma exacerbation and cell damage. Exogenous supplementation of antioxidant combinations has shown potential in asthma management. Previously, a hypoallergenic mutated glutathione S-transferase (mGST) singly or in combination with reduced glutathione (GSH) showed reduction in airway inflammation in mice model. Objective: The present study evaluates the effects of antioxidants α-lipoic acid and α-tocopherol in combination with mGST or GSH in neutralizing the oxidative stress and reducing the inflammatory responses in a mouse model. Materials and Methods: BALB/c mice were immunized and challenged with ovalbumin, treated with different antioxidant combinations by inhalation, and sacrificed to evaluate inflammation and oxidative stress parameters. Result: Treatment with GSH + α-lipoic acid showed significantly reduced total cell and eosinophil counts in bronchoalveolar lavage fluid (BALF) and decreased infiltration of cells into lung interstitium, compared to ovalbumin group. Also, the treatment reduced interleukin (IL)-4 and ovalbumin-specific IgE levels possibly through modulation of redox-sensitive transcription factor nuclear factor-kappa B (NF-κB) levels. Administration of all antioxidant combinations decreased the ROS compared to ovalbumin group as indicated by reduced thiobarbituric acid reactive substance (TBARS) and 8-isoprostane levels in BALF. Conclusion: All antioxidant combinations of α-lipoic acid and α-tocopherol in combination with mGST or GSH showed reduction in airway inflammation and oxidative stress in vivo, but maximum therapeutic efficacy was observed in GSH + α-lipoic acid group. Therefore, a combination of antioxidants may prevent allergic inflammation in the best possible way.

Effect of pigeon pea (Cajanus cajan L.) on high-fat diet-induced hypercholesterolemia in hamsters

Obesity is associated with increased systemic and airway oxidative stress, which may result from a combination of adipokine imbalance and antioxidant defenses reduction. Obesity-mediated oxidative stress plays an important role in the pathogenesis of dyslipidemia, vascular disease, and nonalcoholic hepatic steatosis. The antidyslipidemic activity of pigeon pea were evaluated by high-fat diet (HFD) hamsters model, in which the level of high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), total cholesterol (TC), and total triglyceride (TG) were examined. We found that pigeon pea administration promoted cholesterol converting to bile acid in HFD-induced hamsters, thereby exerting hypolipidemic activity. In the statistical results, pigeon pea significantly increased hepatic carnitine palmitoyltransferase-1 (CPT-1), LDL receptor, and cholesterol 7α-hydroxylase (also known as cytochrome P450 7A1, CYP7A1) expression to attenuate dyslipidemia in HFD-fed hamsters; and markedly elevated antioxidant enzymes in the liver of HFD-induced hamsters, further alleviating lipid peroxidation. These effects may attribute to pigeon pea contained large of unsaturated fatty acids (UFA; C18:2) and phytosterol (β-sitosterol, campesterol, and stigmasterol). Moreover, the effects of pigeon pea on dyslipidemia were greater than β-sitosterol administration (4%), suggesting that phytosterone in pigeon pea could prevent metabolic syndrome.

Secondhand smoke exposure induces acutely airway acidification and oxidative stress

Previous studies have shown that secondhand smoke induces lung function impairment and increases proinflammatory cytokines. The aim of the present study was to evaluate the acute effects of secondhand smoke on airway acidification and airway oxidative stress in never-smokers. In a randomized controlled cross-over trial, 18 young healthy never-smokers were assessed at baseline and 0, 30, 60, 120, 180 and 240min after one-hour secondhand smoke exposure at bar/restaurant levels. Exhaled NO and CO measurements, exhaled breath condensate collection (for pH, H(2)O(2) and NO(2)(-)/NO(3)(-) measurements) and spirometry were performed at all time-points. Secondhand smoke exposure induced increases in serum cotinine and exhaled CO that persisted until 240min. Exhaled breath condensate pH decreased immediately after exposure (p<0.001) and returned to baseline by 180min, whereas H(2)O(2) increased at 120min and remained increased at 240min (p=0.001). No changes in exhaled NO and NO(2)/NO(3) were observed, while decreases in FEV(1) (p<0.001) and FEV(1)/FVC (p<0.001) were observed after exposure and returned to baseline by 180min. A 1-h exposure to secondhand smoke induced airway acidification and increased airway oxidative stress, accompanied by significant impairment of lung function. Despite the reversal in EBC pH and lung function, airway oxidative stress remained increased 4h after the exposure. Clinical trial registration number (EudraCT): 2009-013545-28.