Oxidative stress in asthma and COPD: antioxidants as a therapeutic strategy

Physiological stress in response to multitasking and work interruptions: Study protocol

BACKGROUND

The biopsychological response patterns to digital stress have been sparsely investigated so far. Important potential stressors in modern working environments due to increased digitalization are multitasking and work interruptions. In this study protocol, we present a protocol for a laboratory experiment, in which we will investigate the biopsychological stress response patterns to multitasking and work interruptions.

METHODS

In total, N = 192 healthy, adult participants will be assigned to six experimental conditions in a randomized order (one single-task, three dual-task (two in parallel and one as interruption), one multitasking, and one passive control condition). Salivary alpha-amylase as well as heart rate as markers for Sympathetic Nervous System Activity, heart rate variability as measure for Parasympathetic Nervous System (PNS) activity, and cortisol as measure for activity of the hypothalamic-pituitary adrenal (HPA) axis will be assessed at six time points throughout the experimental session. Furthermore, inflammatory markers (i.e., IL-6, C-reactive protein (CRP), and secretory immunoglobulin-A) will be assessed before and after the task as well as 24 hours after it (IL-6 and CRP only). Main outcomes will be the time course of these physiological stress markers. Reactivity of these measures will be compared between the experimental conditions (dual-tasking, work interruptions, and multitasking) with the control conditions (single-tasking and passive control).

DISCUSSION

With this study protocol, we present a comprehensive experiment, which will enable an extensive investigation of physiological stress-responses to multitasking and work interruptions. Our planned study will contribute to a better understanding of physiological response patterns to modern (digital) stressors. Potential risks and limitations are discussed. The findings will have important implications, especially in the context of digital health in modern working and living environments.

Nutraceuticals and mitochondrial oxidative stress: bridging the gap in the management of bronchial asthma

Asthma is a chronic inflammatory disease primarily characterized by inflammation and reversible bronchoconstriction. It is currently one of the leading causes of morbidity and mortality in the world. Oxidative stress further complicates the pathology of the disease. The current treatment strategies for asthma mainly involve the use of anti-inflammatory agents and bronchodilators. However, long-term usage of such medications is associated with severe adverse effects and complications. Hence, there is an urgent need to develop newer, novel, and safe treatment modalities for the management of asthma. This has therefore prompted further investigations and detailed research to identify and develop novel therapeutic interventions from potent untapped resources. This review focuses on the significance of oxidative stressors that are primarily derived from both mitochondrial and non-mitochondrial sources in initiating the clinical features of asthma. The review also discusses the biological scavenging system of the body and factors that may lead to its malfunction which could result in altered states. Furthermore, the review provides a detailed insight into the therapeutic role of nutraceuticals as an effective strategy to attenuate the deleterious effects of oxidative stress and may be used in the mitigation of the cardinal features of bronchial asthma.

IL-25 Induced ROS-Mediated M2 Macrophage Polarization via AMPK-Associated Mitophagy

Interleukin (IL)-25 is a cytokine released by airway epithelial cells responding to pathogens. Excessive production of reactive oxygen species (ROS) leads to airway inflammation and remodeling in asthma. Mitochondria are the major source of ROS. After stress, defective mitochondria often undergo selective degradation, known as mitophagy. In this study, we examined the effects of IL-25 on ROS production and mitophagy and investigated the underlying mechanisms. The human monocyte cell line was pretreated with IL-25 at different time points. ROS production was measured by flow cytometry. The involvement of mitochondrial activity in the effects of IL-25 on ROS production and subsequent mitophagy was evaluated by enzyme-linked immunosorbent assay, Western blotting, and confocal microscopy. IL-25 stimulation alone induced ROS production and was suppressed by N-acetylcysteine, vitamin C, antimycin A, and MitoTEMPO. The activity of mitochondrial complex I and complex II/III and the levels of p-AMPK and the mitophagy-related proteins were increased by IL-25 stimulation. The CCL-22 secretion was increased by IL-25 stimulation and suppressed by mitophagy inhibitor treatment and PINK1 knockdown. The Th2-like cytokine IL-25 can induce ROS production, increase mitochondrial respiratory chain complex activity, subsequently activate AMPK, and induce mitophagy to stimulate M2 macrophage polarization in monocytes.

The nitroxide/antioxidant 3-carbamoyl proxyl attenuates disease severity in murine models of severe asthma

Asthma is characterized by airway inflammation, hyper-responsiveness, symptoms of dyspnea, wheezing and coughing. In most patients, asthma is well controlled using inhaled corticosteroids and bronchodilators. A minority of patients with asthma develop severe disease, which is frequently only partially responsive or even resistant to treatment with corticosteroids. Severe refractory asthma is associated with structural changes in the airways, termed "airway remodeling", and/or with neutrophilic rather than eosinophilic airway inflammation. While oxidative stress plays an important role in the pathophysiology of asthma, cyclic nitroxide stable radicals, which are unique and efficient catalytic antioxidants, effectively protect against oxidative injury. We have demonstrated that the nitroxide 3-carbamoyl proxyl (3-CP) attenuates airway inflammation and hyperresponsiveness in allergic asthma as well as bleomycin-induced fibrosis both using murine models, most probably through modulation of oxidative stress. The present study evaluates the effect of 3-CP on airway inflammation and remodeling using two murine models of severe asthma where mice are sensitized and challenged either by ovalbumin (OVA) or by house dust mite (HDM). 3-CP was orally administered during the entire period of the experiment or during the challenge period alone where its effect was compared to that of dexamethasone. The induced increase by OVA and by HDM of BALf cell counts, airway hyperresponsiveness, fibrosis, transforming growth factor-beta (TGF-β) levels in BALf and protein nitration levels of the lung tissue was significantly reduced by 3-CP. The effect of 3-CP, using two different murine models of severe asthma, is associated at least partially with attenuation of oxidative stress and with TGF-β expression in the lungs. The results of this study suggest a potential use of 3-CP as a novel therapeutic agent in different forms of severe asthma.

Molecular mechanisms of oxidative stress in asthma

The lungs are exposed to reactive oxygen species oxygen (ROS) produced as a result of inhalation of oxygen, as well as smoke and other air pollutants. Cell metabolism and the NADPH oxidases (Nox) generate low levels of intracellular ROS that act as signal transduction mediators by inducing oxidative modifications of histones, enzymes and transcription factors. Redox signalling is also regulated by localised production and sensing of ROS in mitochondria, the endoplasmic reticulum (ER) and inside the nucleus. Intracellular ROS are maintained at low levels through the action of a battery of enzymatic and non-enzymatic antioxidants. Asthma is a heterogeneous airway inflammatory disease with different immune endotypes; these include atopic or non-atopic Th2 type immune response associated with eosinophilia, or a non-Th2 response associated with neutrophilia. Airway remodelling and hyperresponsiveness accompany the inflammatory response in asthma. Over-production of ROS resulting from infiltrating immune cells, particularly eosinophils and neutrophils, and a concomitant impairment of antioxidant responses lead to development of oxidative stress in asthma. Oxidative stress is augmented in severe asthma and during exacerbations, as well as by air pollution and obesity, and causes oxidative damage of tissues promoting airway inflammation and hyperresponsiveness. Furthermore, deregulated Nox activity, mitochondrial dysfunction, ER stress and/or oxidative DNA damage, resulting from exposure to irritants, inflammatory mediators or obesity, may lead to redox-dependent changes in cell signalling. ROS play a central role in airway epithelium-mediated sensing, development of innate and adaptive immune responses, and airway remodelling and hyperresponsiveness. Nonetheless, antioxidant compounds have proven clinically ineffective as therapeutic agents for asthma, partly due to issues with stability and in vivo metabolism of these compounds. The compartmentalised nature of ROS production and sensing, and the role of ROS in homeostatic responses and in the action of corticosteroids and β2-adrenergic receptor agonists, adds another layer of complexity to antioxidant therapy development. Nox inhibitors and mitochondrial-targeted antioxidants are in clinical development for a number of diseases but they have not yet been investigated in asthma. A better understanding of the complex role of ROS in the pathogenesis of asthma will highlight new opportunities for more targeted and effective redox therapies.

Transcriptome-wide profiling discover: PM2.5 aggravates airway dysfunction through epithelial barrier damage regulated by Stanniocalcin 2 in an OVA-induced model

BACKGROUND

Epidemiologic evidence suggests that PM2.5 exposure aggravates asthma, but the molecular mechanisms are not fully discovered.

METHODS

Ovalbumin (OVA)-induced mice exposed to PM2.5 were constructed. Pathological staining and immunofluorescence were performed in in vivo study. Gene set enrichment analysis (GSEA) was performed to identify the pathway involved in asthma severity by using U-BIOPRED data (human bronchial biopsies) and RNA-seq data (Beas-2B cells treated with PM2.5). Lentiviruses transfection, Real-time qPCR, immunofluorescence staining and trans-epithelial electrical resistance (TEER) measurement were performed for mechanism exploration in vitro.

RESULTS

PM2.5 exposure aggravated airway inflammation and mucus secretion in OVA-induced mice. Based on transcriptome analysis of mild-to-severe asthma from human bronchial biopsies, gene set enrichment analysis (GSEA) showed that up-regulated reactive oxygen species (ROS) pathway gene set and down-regulated apical junction gene set correlated with asthma severity. Consistent with the analysis of mild-to-severe asthma, after PM2.5 exposure, the ROS pathway in Beas-2B cells was up-regulated with the down-regulation of apical junction. The expression levels of genes involved in the specific gene sets were validated by using qPCR. The mRNA levels of junction genes, ZO-1, E-cadherin and Occludin, were significantly decreased in cells exposed to PM2.5. Moreover, it confirmed that inhibition of ROS recovered the expression levels of E-cadherin, Occludin and ZO-1, and ameliorated inflammation and mucus secretion in airway in OVA-induced mice exposed to PM2.5. Meanwhile, ROS level was elevated by PM2.5. By checking trans-epithelial electrical resistance (TEER) value, we also found that epithelial barrier was damaged after PM2.5 exposure. Importantly, Stanniocalcin 2 (STC2) was identified as a key gene in regulation of epithelial barrier. It showed that STC2 expression was up-regulated by PM2.5, which was recovered by NAC as well. Over-expression of STC2 could decrease the expression levels of ZO-1, Occludin and E-cadherin. Contrarily, suppression of STC2 could increase the expression levels of ZO-1, Occludin and E-cadherin reduced by PM2.5.

CONCLUSIONS

By using transcriptome analysis, we revealed that STC2 played a key role in PM2.5 aggravated airway dysfunction through regulation of epithelial barrier in OVA-induced mice.

Exhaled volatilome analysis as a useful tool to discriminate asthma with other coexisting atopic diseases in women of childbearing age

The prevalence of asthma is considerably high among women of childbearing age. Most asthmatic women also often have other atopic disorders. Therefore, the differentiation between patients with atopic diseases without asthma and asthmatics with coexisting diseases is essential to avoid underdiagnosis of asthma and to design strategies to reduce symptom severity and improve quality of life of patients. Hence, we aimed for the first time to conduct an analysis of volatile organic compounds in exhaled breath of women of childbearing age as a new approach to discriminate between asthmatics with other coexisting atopic diseases and non-asthmatics (with or without atopic diseases), which could be a helpful tool for more accurate asthma detection and monitoring using a noninvasive technique in the near future. In this study, exhaled air samples of 336 women (training set (n = 211) and validation set (n = 125)) were collected and analyzed by thermal desorption coupled with gas chromatography-mass spectrometry. ASCA (ANOVA (analysis of variance) simultaneous component analysis) and LASSO + LS (least absolute shrinkage and selection operator + logistic regression) were employed for data analysis. Fifteen statistically significant models (p-value < 0.05 in permutation tests) that discriminated asthma with other coexisting atopic diseases in women of childbearing age were generated. Acetone, 2-ethyl-1-hexanol and a tetrahydroisoquinoline derivative were selected as discriminants of asthma with other coexisting atopic diseases. In addition, carbon disulfide, a tetrahydroisoquinoline derivative, 2-ethyl-1-hexanol and decane discriminated asthma disease among patients with other atopic disorders. Results of this study indicate that refined metabolomic analysis of exhaled breath allows asthma with other coexisting atopic diseases discrimination in women of reproductive age.

Vitamin D Supplementation: Oxidative Stress Modulation in a Mouse Model of Ovalbumin-Induced Acute Asthmatic Airway Inflammation

Asthma oxidative stress disturbances seem to enable supplementary proinflammatory pathways, thus contributing to disease development and severity. The current study analyzed the impact of two types of oral vitamin D (VD) supplementation regimens on the redox balance using a murine model of acute ovalbumin-induced (OVA-induced) asthmatic inflammation. The experimental prevention group received a long-term daily dose of 50 µg/kg (total dose of 1300 µg/kg), whereas the rescue group underwent a short-term daily dose of 100 µg/kg (total dose of 400 µg/kg). The following oxidative stress parameters were analyzed in serum, bronchoalveolar lavage fluid (BALF) and lung tissue homogenate (LTH): total oxidative status, total antioxidant response, oxidative stress index, malondialdehyde and total thiols. Results showed that VD significantly reduced oxidative forces and increased the antioxidant capacity in the serum and LTH of treated mice. There was no statistically significant difference between the two types of VD supplementation. VD also exhibited an anti-inflammatory effect in all treated mice, reducing nitric oxide formation in serum and the expression of nuclear factor kappa B p65 in the lung. In conclusion, VD supplementation seems to exhibit a protective role in oxidative stress processes related to OVA-induced acute airway inflammation.

PM2.5 aggravates NQO1-induced mucus hyper-secretion through release of neutrophil extracellular traps in an asthma model

BACKGROUND

Particulate matter of 2.5 µm or less in diameter (PM2.5) is one of the most complex pollutants in the atmospheric environment and harmful to human health. Epidemiologic evidence suggests that asthma exacerbation is associated with PM2.5 exposure. However, the molecular mechanism of PM2.5 in the development of asthma is not fully addressed.

METHODS

PM2.5 was collected from Chengdu, China, and the components were analyzed. The relationship between PM2.5 exposure and asthma severity was investigated in an Ovalbumin (OVA)-induced murine model of asthma. U-BIOPRED data from public database and our own RNA-seq data were analyzed to identify the hub genes. Real-time qPCR, immunofluorescence, immunohistochemistry and pathological staining were applied for mechanism dissection in both in vitro and in vivo studies.

RESULTS

In PM2.5 samples, a total of 11 elements including major elements and trace elements were identified, 14 of the 16 Polycyclic aromatic hydrocarbons (PAHs) were detected except Acenaphthene and Fluorene. PM2.5 exposure aggravated pulmonary inflammation, mucus secretion, and neutrophils infiltration in asthma model. Based on transcriptome analysis of mild-to-severe asthma dataset, it showed that mucus secretion and neutrophil degranulation correlated with asthma severity. Moreover, NAD(P)H:quinone oxidoreductase 1 (NQO1) was screened out as a hub gene whose expression positively correlated with MUC5AC expression in patient with asthma by performing joint analysis. Furthermore, in OVA-induced asthma model and in vitro assay, it also revealed that PM2.5-induced MU5AC expression was regulated by NQO1 through neutrophil extracellular traps (NETs) caused by oxidative stress.

CONCLUSION

Taken together, we discovered a potential relationship between asthma severity and PM2.5 exposure. In addition, neutrophil depletion, NETs inhibition or anti-NQO1 might be novel potential therapeutic options for treatment of PM2.5-induced mucus hyper-secretion.

Effects of Anacardic Acid Monoene on the Respiratory System of Mice Submitted to Acute Respiratory Distress Syndrome

The acute respiratory distress syndrome caused by viral pathogens is a worldwide public health emergency. It is suggested that patients with this condition should be screened using therapies that address the need to prevent mortality. Anacardic acids found in Anacardium species have biological activities related to the antioxidant capacity of their double bonds in the lateral alkyl chain. The present study seeks to investigate the effects of anacardic acid monoene on acute respiratory distress syndrome caused by lipopolysaccharides. Experiments were carried out on mice divided into three groups: control group, acute respiratory distress-induced group, and anacardic acid monoene pretreated group, subsequently, induced to acute respiratory distress by lipopolysaccharides. Results showed that anacardic acid moeno was able to prevent changes in lung function and preserve its mechanical properties from containing inflammatory cell infiltrate, collapse of alveoli, and decreased airway resistance, suggesting that this compound may be effective in preventing the acute respiratory distress syndrome caused by viral pathogens.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s43450-021-00151-8.

Simulated biological fluids - a systematic review of their biological relevance and use in relation to inhalation toxicology of particles and fibres

The use of simulated biological fluids (SBFs) is a promising in vitro technique to better understand the release mechanisms and possible in vivo behaviour of materials, including fibres, metal-containing particles and nanomaterials. Applications of SBFs in dissolution tests allow a measure of material biopersistence or, conversely, bioaccessibility that in turn can provide a useful inference of a materials biodistribution, its acute and long-term toxicity, as well as its pathogenicity. Given the wide range of SBFs reported in the literature, a review was conducted, with a focus on fluids used to replicate environments that may be encountered upon material inhalation, including extracellular and intracellular compartments. The review aims to identify when a fluid design can replicate realistic biological conditions, demonstrate operation validation, and/or provide robustness and reproducibility. The studies examined highlight simulated lung fluids (SLFs) that have been shown to suitably replicate physiological conditions, and identify specific components that play a pivotal role in dissolution mechanisms and biological activity; including organic molecules, redox-active species and chelating agents. Material dissolution was not always driven by pH, and likewise not only driven by SLF composition; specific materials and formulations correspond to specific dissolution mechanisms. It is recommended that SLF developments focus on biological predictivity and if not practical, on better biological mimicry, as such an approach ensures results are more likely to reflect in vivo behaviour regardless of the material under investigation.

Pirfenidone mediates cigarette smoke extract induced inflammation and oxidative stress in vitro and in vivo

BACKGROUND

Antioxidant and anti-inflammatory effects are two main pharmacological mechanisms of pirfenidone (PFD) besides the anti-fibrotic effect. This study aims to investigate whether PFD could mediate cigarette smoke extract (CSE) induced inflammation and oxidative stress in vitro and in vivo.

METHODS

BALB/C mice and alveolar epithelial (A549) cells treated with CSE were established as disease models in vivo and in vitro. Effects of PFD treatment on disease models were further measured. Hematoxylin and eosin (HE) staining was used to evaluate the pathological changes in lung tissues of mice. CCK-8 assay kit was applied to measure the viability of A549 cells treated by different concentrations of PFD. Inflammation cytokine expression in cell supernatants was measured with ELISA kits. The mRNA and protein levels of inflammation and oxidative stress-related factors were determined by real-time quantitative polymerase chain reaction analysis (RT-qPCR) and Western blotting. Furthermore, myeloperoxidase (MPO), malondialdehyde (MDA), and total antioxidant capacity (T-AOC) were measured to detect the antioxidative activity of lung tissues. Moreover, an assay kit with fluorescent probe 2',7'-dichlorofluorescin diacetate (DCFH-DA) was used to evaluate the intracellular reactive oxygen species (ROS) generation.

RESULTS

In vitro and in vivo, PFD significantly reversed TNF-α, IL-6, CCL2, SOD1, and CAT mRNA level changes led by CSE; in addition, PFD significantly decreased the ratios of p-p65 to p65, p-ikBα to ikBα and increased Nrf-2 protein level compared with CSE group. In mice, high-dose (100 mg/kg/d) PFD significantly reversed MPO and MDA increases induced by CSE. However, PFD didn't significantly reverse T-AOC decrease induced by CSE. In A549 cell supernatant, PFD dramatically reversed the elevated levels of TNF-α and IL-1β induced by CSE. Furthermore, PFD could significantly reverse the increased level of ROS induced by CSE in A549 cells.

CONCLUSION

Our study reveals the potential role of PFD in regulating inflammatory response and oxidative stress induced by CSE.

The Association between Vigorous Physical Activity and Stress in Adolescents with Asthma

Asthma is a very common condition that affects 5-10% of the global population, and its prevalence is increasing. Vigorous physical activity (PA) is effective in improving cardiorespiratory fitness and managing stress. This study aimed to investigate the association between vigorous PA and stress among Korean adolescents with asthma using large-scale survey data. The questionnaire data of 57,303 adolescents were analyzed using raw data from the 2019 Korea Youth Risk Behavior Web-Based Survey. We performed logistic regression analysis to calculate the stress odds ratios (ORs) and 95% confidence intervals (CIs) for asthma and non-asthma groups using models 1 and 2. We also performed logistic regression analysis to calculate the stress OR for the asthma group with vigorous PA and non-vigorous PA using models 1, 2, and 3. Model 1 was adjusted for age, sex, obesity, smoking, and alcohol status; model 2 was further adjusted for household income, academic achievement, and comorbidities. Model 3 was further adjusted for moderate activity and resistance exercise. The OR of stress was 20% higher in the asthma group than in the non-asthma group (p < 0.05). In the fully adjusted models, the OR for the non-asthma group with vigorous PA versus non-vigorous PA was 0.89 (95% CI: 0.84-0.94). However, the OR for the asthma group with vigorous PA versus non-vigorous PA was 0.70 (95% CI: 0.57-0.86), indicating that adolescents who engage in vigorous PA had lower stress in the asthma group (p < 0.05). This study demonstrated that adolescents with asthma had higher stress levels than those without asthma; however, vigorous PA was associated with lower stress. These effects were more pronounced in adolescents with asthma.

Effects of E-Cigarette Aerosols with Varying Levels of Nicotine on Biomarkers of Oxidative Stress and Inflammation in Mice

To provide insights into the cause of e-cigarette (e-cig) associated lung injury, we examined the effects of propylene glycol (PG) and glycerol (G), two common solvent carriers used to deliver nicotine/flavor, on markers of oxidative stress and inflammation in female B6C3F1 mice which had been used successfully in tobacco smoke (TS)-induced lung carcinogenesis. Mice exposed to air and TS were used as negative and positive controls, respectively. Using LC-MS/MS, we showed that PG/G alone, in the absence of nicotine, significantly increased the levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG or its tautomer 8-oxodG), a biomarker of DNA oxidative damage, in lung and plasma of mice; moreover, addition of nicotine (12 and 24 mg/mL) in e-cig liquid appears to suppress the levels of 8-oxodG. Exposure to e-cig aerosols or TS induced nonsignificant increases of plasma C-reactive protein (CRP), a biomarker of inflammation; nonetheless, the levels of fibronectin (FN), a biomarker of tissue injury, were significantly increased by e-cig aerosols or TS. Although preliminary, our data showed that exposure to e-cig aerosols induced a higher score of lung injury than did control air or TS exposure. Our results indicate that the B6C3F1 mouse model may be suitable for an in-depth examination of the impact of e-cig on lung injury associated with oxidative stress and inflammation and this study adds to the growing evidence that the use of e-cig can lead to lung damage.

Acrylamide Induces Mitophagy and Alters Macrophage Phenotype via Reactive Oxygen Species Generation

Acrylamide is a readily exposed toxic organic compound due to its formation in many carbohydrate rich foods that are cooked at high temperatures. Excessive production of reactive oxygen species (ROS), which is an important factor for mitophagy, has been reported to lead to airway inflammation, hyper-responsiveness, and remodeling. Epigenetic regulation is an important modification affecting gene transcription. In this study, the effects of acrylamide on ROS productions and mitophagy were investigated. The human monocytic cell line THP-1 was treated with acrylamide, and ROS productions were investigated by flow cytometry. The mitochondrial and epigenetic involvement was evaluated by quantitative real-time PCR. Histone modifications were examined by chromatin immunoprecipitation assays. Mitophagy was detected by Western blotting and confocal laser microscopy. Acrylamide promoted mitochondria-specific ROS generation in macrophages. The gene expression of mitochondrial respiratory chain complex II SDHA was increased under acrylamide treatment. Acrylamide induced histone H3K4 and H3K36 tri-methylation in an SDHA promoter and increased mitophagy-related PINK1 expression, which promoted a M2-like phenotypic switch with increase TGF-β and CCL2 levels in THP-1 cells. In conclusion, acrylamide induced ROS production through histone tri-methylation in an SDHA promoter and further increased the expression of mitophagy-related PINK-1, which was associated with a macrophage M2 polarization shift.

Gymnema inodorum (Lour.) Decne. Extract Alleviates Oxidative Stress and Inflammatory Mediators Produced by RAW264.7 Macrophages

Gymnema inodorum (Lour.) Decne. (G. inodorum) is widely used in Northern Thai cuisine as local vegetables and commercial herb tea products. In the present study, G. inodorum extract (GIE) was evaluated for its antioxidant and anti-inflammatory effects in LPS plus IFN-γ-induced RAW264.7 cells. Major compounds in GIE were evaluated using GC-MS and found 16 volatile compounds presenting in the extract. GIE exhibited antioxidant activity by scavenging the intracellular reactive oxygen species (ROS) production and increasing superoxide dismutase 2 (SOD2) mRNA expression in LPS plus IFN-γ-induced RAW264.7 cells. GIE showed anti-inflammatory activity through suppressing nitric oxide (NO), proinflammatory cytokine production interleukin 6 (IL-6) and also downregulation of the expression of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), and IL-6 mRNA levels in LPS plus IFN-γ-induced RAW264.7 cells. Mechanism studies showed that GIE suppressed the NF-κB p65 nuclear translocation and slightly decreased the phosphorylation of NF-κB p65 (p-NF-κB p65) protein. Our studies applied the synchrotron radiation-based FTIR microspectroscopy (SR-FTIR), supported by multivariate analysis, to identify the FTIR spectral changes based on macromolecule alterations occurring in RAW264.7 cells. SR-FTIR results demonstrated that the presence of LPS plus IFN-γ in RAW264.7 cells associated with the increase of amide I/amide II ratio (contributing to the alteration of secondary protein structure) and lipid content, whereas glycogen and other carbohydrate content were decreased. These findings lead us to believe that GIE may prevent oxidative damage by scavenging intracellular ROS production and activating the antioxidant gene, SOD2, expression. Therefore, it is possible that the antioxidant properties of GIE could modulate the inflammation process by regulating the ROS levels, which lead to the suppression of proinflammatory cytokines and genes. Therefore, GIE could be developed into a novel antioxidant and anti-inflammatory agent to treat and prevent diseases related to oxidative stress and inflammation.

Cellular and Biochemical Analysis of Bronchoalveolar Lavage Fluid from Murine Lungs

Bronchoalveolar lavage (BAL) is a technique used to collect the contents of the airways. The fluid recovered, called BAL fluid (BALF), serves as a dynamic tool to identify various disease pathologies ranging from asthma to infectious diseases to cancer in the lungs. A wide array of tests can be performed with BALF, including total and differential leukocyte counts (DLC), enzyme-linked immunosorbent assays (ELISA) or flow-cytometric quantitation of inflammatory mediators, such as cytokines, chemokines and adhesion molecules, and assessment of nitrate and nitrite content for estimation of nitric oxide synthase (NOS) activity. Here, we describe a detailed procedure for the collection of BALF for a variety of downstream usages, including DLC by cytological and flow-cytometry-based methods, multiplex cytokine analysis by flow cytometry, and NOS activity analysis by determining nitrate and nitrite levels.

Casticin Improves Respiratory Dysfunction and Attenuates Oxidative Stress and Inflammation via Inhibition of NF-ĸB in a Chronic Obstructive Pulmonary Disease Model of Chronic Cigarette Smoke-Exposed Rats

Objective

The present study was conducted to elucidate the protective effect of Casticin against chronic obstructive pulmonary disease (COPD) in rats.

Methods

The COPD in rats was induced by the controlled cigarette smoke, and CST (10, 20, and 30 mg/kg) was injected into the cigarette-smoke exposed rats. Blood was taken from the abdominal vein and centrifuged (1500×g, 4°C, 15min); plasma was collected and used for the determination of various biochemical parameters.

Results

The results of the study suggested that CST significantly improved the lung functions of the rats in a dose-dependent manner. It also causes a reduction of white blood cells, neutrophils, and macrophages in BALF of rats. The plasma level of leptin and C-reactive protein together with pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) were also significantly restored to near to normal in CST-treated group. In Western blot analysis, CST causes significant inhibition of the NF-ĸB and iNOS pathway.

Conclusion

Our study demonstrated that the CST protects lungs against COPD via improving lung functions and inhibition of oxidative stress and inflammation.

Formononetin Attenuates Airway Inflammation and Oxidative Stress in Murine Allergic Asthma

Allergic asthma has been considered as a respiratory disorder with pathological features of airway inflammation and remodeling, which involves oxidative stress. Formononetin (FMT) is a bioactive isoflavone obtained from Chinese herb Radix Astragali, and has been reported to have notable anti-inflammatory and antioxidant effects in several diseases. The purpose of our study was to elaborate the effects of FMT on asthma and the underlying mechanisms. To establish allergic asthma model, BALB/c mice were given ovalbumin (OVA) sensitization and challenge, treated with FMT (10, 20, 40 mg/kg) or dexamethasone (2 mg/kg). The effects of FMT on lung inflammation and oxidative stress were assessed. In OVA-induced asthmatic mice, FMT treatments significantly ameliorated lung function, alleviated lung inflammation including infiltration of inflammatory cells, the elevated levels of interleukin (IL)-4, IL-5, and IL-13, immunoglobulin (Ig) E, C-C motif chemokine ligand 5 (CCL5, also known as RANTES), CCL11 (also called Eotaxin-1), and IL-17A. In addition, FMT treatments eminently blunted goblet cell hyperplasia and collagen deposition, and remarkably reduced oxidative stress as displayed by decreased reactive oxygen species (ROS), and increased superoxide diamutase (SOD) activity. Furthermore, to clarify the potential mechanisms responsible for the effects, we determined the inflammation and oxidation-related signaling pathway including nuclear factor kappa β (NF-κB), c-Jun N-terminal kinase (JNK), and the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2). FMT treatments appeared to dramatically inhibit the activation of NF-κB and JNK, significantly elevated the expression of heme oxygenase 1 (HO-1) but failed to activate expression of Nrf2. In conclusion, our study suggested that FMT had the therapeutic effects in attenuating airway inflammation and oxidative stress in asthma.

Free Radical and Nicotine Yields in Mainstream Smoke of Chinese Marketed Cigarettes: Variation with Smoking Regimens and Cigarette Brands

Free radicals and nicotine are components of cigarette smoke that are thought to contribute to the development of smoking-induced diseases. China has the largest number of smokers in the world, yet little is known about the yields of tobacco smoke constituents in different Chinese brands of cigarettes. In this study, gas-phase and particulate-phase free radicals as well as nicotine yields were quantified in mainstream cigarette smoke from five popular Chinese brands and two research cigarettes (3R4F and 1R6F). Mainstream smoke was generated under International Organization of Standardization (ISO) and Canadian Intense (CI) smoking regimens using a linear smoking machine. Levels of free radicals and nicotine were measured by electron paramagnetic resonance spectroscopy (EPR) and gas chromatography with flame-ionization detection, respectively. Under the ISO puffing regimen, Chinese brand cigarettes produced an average of 3.0 ± 1.2 nmol/cig gas-phase radicals, 118 ± 44.7 pmol/cig particulate-phase radicals, and 0.6 ± 0.2 mg/cig nicotine. Under the CI puffing regimen, Chinese brand cigarettes produced an average of 5.6 ± 1.2 nmol/cig gas-phase radicals, 282 ± 92.1 pmol/cig particulate-phase radicals, and 2.1 ± 0.4 mg/cig nicotine. Overall, both gas- and particulate-phase free radicals were substantially lower compared to the research cigarettes under both regimens, whereas no significant differences were observed for nicotine levels. When Chinese brands were compared, the highest free radical and nicotine yields were found in "LL" and "BS" brands, while lowest levels were found in "YY". These results suggested that the lower radical delivery by Chinese cigarettes compared to United States reference cigarettes may be associated with reductions in oxidant-related harm.

Thymoquinone (Tq) protects necroptosis induced by autophagy/mitophagy-dependent oxidative stress in human bronchial epithelial cells exposed to cigarette smoke extract (CSE)

Chronic obstructive pulmonary disease (COPD) is characterized by cigarette smoke-induced emphysema. Herein, we demonstrate protective effects of Thymoquinone (Tq), an active constituent from Nigella sativa, against cigarette smoke extract (CSE)-induced abnormalities in bronchial epithelial cells. Dose-dependent reduction in cell viability was observed in BEAS-2B cells when exposed to different CSE concentrations, which was significantly reversed by Tq evident by LDH release. Levels of SOD, CAT, G_R , GSH, and mitochondrial membrane ATPases were significantly reduced upon CSE exposure, an event, again, antagonized in presence of Tq. Similarly, Tq treatment significantly blocked CSE-induced 4HNE elevations. Further, Tq-improved mitochondrial dysfunction caused by CSE and significantly decreased autophagy/mitophagy markers like LC3II and p-Drp. Tq also reduced necroptosis markers such as p-MLKL, RIP-1, and RIP-3, by stabilizing PINK-1 levels. In summary, Tq possesses protective properties against human bronchial epithelial cell autophagy/mitophagy-dependent necroptosis caused by CSE, which warrants considerable attention for further preclinical evaluations. PRACTICAL APPLICATIONS: This study demonstrates Thymoquinone (Tq), a natural plant extract to possess protective properties against human bronchial epithelial cell autophagy/mitophagy-dependent necroptosis caused by cigarette smoke extract. The demonstrated efficacy of Tq will throw light for further preclinical evaluation of this molecule in CSE-mediated complications. A detailed in vivo research is recommended.

Biomarkers of Oxidative Stress and Inflammation in Chronic Airway Diseases

Introduction: The global burden of chronic airway diseases represents an important public health concern. The role of oxidative stress and inflammation in the pathogenesis of these diseases is well known. The aim of this study is to evaluate the behavior of both inflammatory and oxidative stress biomarkers in patients with chronic bronchitis, current asthma and past asthma in the frame of a population-based study. Methods: For this purpose, data collected from the Gene Environment Interactions in Respiratory Diseases (GEIRD) Study, an Italian multicentre, multicase-control study, was evaluated. Cases and controls were identified through a two-stage screening process of individuals aged 20-65 years from the general population. Out of 16,569 subjects selected from the general population in the first stage of the survey, 2259 participated in the clinical evaluation. Oxidative stress biomarkers such as 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG), 8-isoprostane and glutathione and inflammatory biomarkers such as Fractional Exhaled Nitric Oxide (FENO) and white blood cells were evaluated in 1878 subjects. Results: Current asthmatics presented higher levels of FENO (23.05 ppm), leucocytes (6770 n/µL), basophils (30.75 n/µL) and eosinophils (177.80 n/µL), while subjects with chronic bronchitis showed higher levels of GSH (0.29 mg/mL) and lymphocytes (2101.6 n/µL). The multivariable multinomial logistic regression confirmed high levels of leucocytes (RRR = 1.33), basophils (RRR = 1.48), eosinophils (RRR = 2.39), lymphocytes (RRR = 1.26) and FENO (RRR = 1.42) in subjects with current asthma. Subjects with past asthma had a statistically significant higher level of eosinophils (RRR = 1.78) with respect to controls. Subjects with chronic bronchitis were characterized by increased levels of eosinophils (RRR = 2.15), lymphocytes (RRR = 1.58), GSH (RRR = 2.23) and 8-isoprostane (RRR = 1.23). Conclusion: In our study, current asthmatics show a greater expression of the inflammatory profile compared to subjects who have had asthma in the past and chronic bronchitis. On the other hand, chronic bronchitis subjects showed a higher rate of expression of oxidative stress biomarkers compared to asthmatic subjects. In particular, inflammatory markers such as circulating inflammatory cells and FENO seem to be more specific for current asthma, while oxidative stress biomarkers such as glutathione and 8-isoprostane appear to be more specific and applicable to patients with chronic bronchitis.

Theophylline and dexamethasone in combination reduce inflammation and prevent the decrease in HDAC2 expression seen in monocytes exposed to cigarette smoke extract

Lung and systemic inflammation are associated with impaired lung function and increased mortality in patients with chronic obstructive pulmonary disease (COPD). Theophylline and glucocorticoids have been shown to have an anti-inflammatory effect in some respiratory diseases. However, corticosteroid insensitivity is a major barrier to the anti-inflammatory management of COPD. This study aimed to explore whether a combined treatment of theophylline and dexamethasone (Dex) could decrease cigarette smoke extract (CSE)-induced inflammation via prevention of a reduction in histone deacetylase 2 (HDAC2) expression and through inhibition of the PI3K/Akt pathway, which may be related to corticosteroid sensitivity. The half-maximal inhibitory concentration (IC50) of Dex (IC50-Dex) was used to as a marker of corticosteroid sensitivity. IC50-Dex was determined through observation of Dex inhibition of tumor necrosis factor-α (TNF-α)-induced interleukin (IL)-8 release. Using reverse transcription quantitative PCR and western blotting, U937 cells treated with CSE were assessed for HDAC2 expression levels and phosphorylation levels of Akt. Theophylline and Dex pre-treatment was shown to significantly reduce the CSE-induced release of IL-8 and TNF-α. The combination of theophylline and Dex pretreatment also reversed corticosteroid insensitivity in CSE-induced U937 cells and inhibited the PI3K/AKT pathway to a greater extent than theophylline treatment alone. CSE-treated U937 cells showed a reduction in HDAC2 mRNA and protein expression compared with the control group. However, this effect was reduced after pre-incubation with the combined therapy or theophylline alone. In conclusion, pretreatment with theophylline and Dex decreased CSE-induced inflammation via inhibition of the PI3K/Akt pathway and increase in HDAC2 protein expression.

Free Radical, Carbonyl, and Nicotine Levels Produced by Juul Electronic Cigarettes

INTRODUCTION

Free radicals and carbonyls produced by electronic cigarettes (e-cigs) have the potential to inflict oxidative stress. Recently, Juul e-cigs have risen drastically in popularity; however, there is no data on nicotine and oxidant yields from this new e-cig design.

METHODS

Aerosol generated from four different Juul flavors was analyzed for carbonyls, nicotine, and free radicals. The e-liquids were analyzed for propylene glycol (PG) and glycerol (GLY) concentrations. To determine the effects of e-liquid on oxidant production, Juul pods were refilled with nicotine-free 30:70 or 60:40 PG:GLY with or without citral.

RESULTS

No significant differences were found in nicotine (164 ± 41 µg/puff), free radical (5.85 ± 1.20 pmol/puff), formaldehyde (0.20 ± 0.10 µg/puff), and acetone (0.20 ± 0.05 µg/puff) levels between flavors. The PG:GLY ratio in e-liquids was ~30:70 across all flavors with GLY being slightly higher in tobacco and mint flavors. In general, when Juul e-liquids were replaced with nicotine-free 60:40 PG:GLY, oxidant production increased up to 190% and, with addition of citral, increased even further.

CONCLUSIONS

Juul devices produce free radicals and carbonyls, albeit, at levels substantially lower than those observed in other e-cig products, an effect only partially because of a low PG:GLY ratio. Nicotine delivery by these devices was as high as or higher than the levels previously reported from cigarettes.

IMPLICATIONS

These findings suggest that oxidative stress and/or damage resulting from Juul use may be lower than that from cigarettes or other e-cig devices; however, the high nicotine levels are suggestive of a greater addiction potential.

A prenatally disrupted airway epithelium orchestrates the fetal origin of asthma in mice

BACKGROUND

Prenatal challenges such as maternal stress perception increase the risk and severity of asthma during childhood. However, insights into the trajectories and targets underlying the pathogenesis of prenatally triggered asthma are largely unknown. The developing lung and immune system may constitute such targets.

OBJECTIVE

Here we have aimed to identify the differential sex-specific effects of prenatal challenges on lung function, immune response, and asthma severity in mice.

METHODS

We generated bone marrow chimeric (BMC) mice harboring either prenatally stress-exposed lungs or a prenatally stress-exposed immune (hematopoietic) system and induced allergic asthma via ovalbumin. Next-generation sequencing (RNA sequencing) of lungs and assessment of airway epithelial barrier function in ovalbumin-sensitized control and prenatally stressed offspring was also performed.

RESULTS

Profoundly enhanced airway hyperresponsiveness, inflammation, and fibrosis were exclusively present in female BMC mice with prenatally stress-exposed lungs. These effects were significantly perpetuated if both the lungs and the immune system had been exposed to prenatal stress. A prenatally stress-exposed immune system alone did not suffice to increase the severity of these asthma features. RNA sequencing analysis of lungs from prenatally stressed, non-BMC, ovalbumin-sensitized females unveiled a deregulated expression of genes involved in asthma pathogenesis, tissue remodeling, and tight junction formation. It was also possible to independently confirm a tight junction disruption. In line with this, we identified an altered perinatal and/or postnatal expression of genes involved in lung development along with an impaired alveolarization in female prenatally stressed mice.

CONCLUSION

Here we have shown that the fetal origin of asthma is orchestrated by a disrupted airway epithelium and further perpetuated by a predisposed immune system.

Dataset on part replacement of dipalmitoylphophatidylcholine with locust bean on stimulated tracheobronchial fluid, in vitro bioaccessibility test and modeling of lung deposition of trace elements bound to airborne particulates

The data presented in this article are related to our work on development of tracheobronchial fluid, in vitro bioaccessibility test and modeling of lung deposition of trace elements bound to airborne particulates [1]. In this article, a neutral modeled tracheobronchial fluid was formulated by partial replacement of some constituents in recipes of previously used lung epithelium fluids with local materials and was used in in vitro bioaccessibility extraction of elements-bound to airborne particulates. Dataset of particulate matters-bound trace elements collected in selected locations Ado - Ekiti is presented and the deposition of elements in different regions of respiratory tracts is estimated using Multiple-path particle deposition (MPPD) mathematic model. The data reveals that the formulated fluid has physical characteristics with superior properties to the existing fluids. The data also shows that bioaccessibility of elements were generally low (<30%) except for Cd and As with relatively moderate values (between 45 and 50%). Additionally, the lung deposition modeling shows that greater percentage of Cd (about 40% of inhaled dose) deposition in the lower alveolar part of the respiratory tract while tracheobronchial and extra-thoracic had 33% and 27% respectively. The data sets can be used as references to analyze data obtained using other formulation.

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.

Aqueous Pyrostegia venusta (Ker Gawl.) Miers extract attenuates allergen-induced asthma in a mouse model via an antioxidant mechanism

Objective: Pyrostegia venusta (Ker-Gawl.) Miers (Bignoniaceae) is a perennial invasive vine, distributed worldwide. In folk medicine, its parts are used for the treatment of inflammatory respiratory diseases. Extracts of P. venusta have antioxidant, antimicrobial, and antinociceptive properties. The aim of this study was to evaluate the effects of two extracts (aqueous and hydroethanolic) of P. venusta in the treatment of asthma in an animal model.Methods: Balb/c mice were sensitized twice with ovalbumin (OVA) intraperitoneally (ip), one week apart, and after one week, challenged with OVA intranasally on four alternate days. Mice were treated ip with 300 mg/kg of aqueous or hydroethanolic extracts for seven consecutive days. Control groups received saline on the same days. Bronchial hyperresponsiveness, production of Th1 and Th2 cytokines, lung and airway inflammation, and antioxidant activity in lung tissue were assessed.Results: Treatment with aqueous extract significantly decreased bronchial hyperresponsiveness, measured by total and tissue resistance and elastance. The administration of hydroethanolic extract did not reduce bronchial hyperresponsiveness. In addition, both extracts significantly reduced total cell and eosinophil counts in bronchoalveolar lavage. Both extracts did not change significantly IL-4, IL-5, IL-9, IL-13, IFN-gamma, and TGF-beta levels. Of note, only the aqueous extract significantly increased the total antioxidant activity and reduced lung inflammation.Conclusion: Aqueous extract of P. venusta reduced bronchial hyperresponsiveness, lung and airway inflammation, probably via an antioxidant mechanism. These results demonstrate that P. venusta may have potential for asthma treatment.

Dietary Advanced Glycation Endproducts Decrease Glucocorticoid Sensitivity In Vitro

Glucocorticoids are very effective anti-inflammatory drugs and widely used for inflammatory bowel disease (IBD) patients. However, approximately 20% of IBD patients do not respond to glucocorticoids and the reason for this is largely unknown. Dietary advanced glycation endproducts (AGEs) are formed via the Maillard reaction during the thermal processing of food products and can induce a pro-inflammatory reaction in human cells. To investigate whether this pro-inflammatory response could be mitigated by glucocorticoids, human macrophage-like cells were exposed to both LPS and AGEs to induce interleukin-8 (IL8) secretion. This pro-inflammatory response was then modulated by adding pharmacological compounds interfering in different steps of the anti-inflammatory mechanism of glucocorticoids: rapamycin, quercetin, and theophylline. Additionally, intracellular reactive oxygen species (ROS) were measured and the glucocorticoid receptor phosphorylation state was assessed. The results show that AGEs induced glucocorticoid resistance, which could be mitigated by quercetin and rapamycin. No change in the phosphorylation state of the glucocorticoid receptor was observed. Additionally, intracellular ROS formation was induced by AGEs, which was mitigated by quercetin. This suggests that AGE-induced ROS is an underlying mechanism to AGE-induced glucocorticoid resistance. This study shows for the first time the phenomenon of dietary AGE-induced glucocorticoid resistance due to the formation of ROS. Our findings indicate that food products with a high inflammatory potential can induce glucocorticoid resistance; these results may be of great importance to IBD patients suffering from glucocorticoid resistance.

Andrographolide attenuates oxidative stress injury in cigarette smoke extract exposed macrophages through inhibiting SIRT1/ERK signaling

Andrographolide (AG), an ingredient extracted from traditional Chinese herbal medicine Andrographis paniculata, has been demonstrated to have potent anti-inflammatory and anti-oxidative stress properties. The purpose of this study was to investigate whether and how AG attenuated CSE-induced mitochondrial dysfunction, inflammation and oxidative stress in RAW 264.7 cells (a mouse macrophages line). The results showed that AG significantly reduced CSE-induced upregulation of pro-inflammatory cytokines (i.e., TNF-α and IL-1β) in the RAW 264.7 cells. AG inhibited CSE-induced production of reactive oxygen species (ROS) and prevented the reduction of superoxide dismutase (SOD) and glutathione/oxidized glutathione (GSH/GSSG) ratio, indicating the anti-oxidative stress effects of AG in macrophages. AG also improved mitochondrial function and mitochondrial membrane potential. In addition, AG inhibited CSE-induced increase of heme oxygenase (HO)-1, matrix metalloproteinase (MMP)-9 and MMP-12. Moreover, AG increased SIRT1 transcription and expression, suggesting AG inhibits mitochondrial dysfunction, inflammation and oxidative stress via a SIRT1 dependent signaling. We also demonstrated that AG inhibited CSE-induced ERK phosphorylation, and treatment with PD980589, a ERK inhibitor, reversed CSE-induced inflammation and oxidative stress. These results indicated that AG may prevent COPD via the inhibition of SIRT1/ERK signaling pathway, and subsequently inhibition of mitochondrial dysfunction, inflammation, and oxidative stress in macrophages.

CD44 Loss Disrupts Lung Lipid Surfactant Homeostasis and Exacerbates Oxidized Lipid-Induced Lung Inflammation

Alveolar macrophages (AMs) are CD44 expressing cells that reside in the alveolar space where they maintain lung homeostasis by serving critical roles in immunosurveillance and lipid surfactant catabolism. AMs lacking CD44 are unable to bind the glycosaminoglycan, hyaluronan, which compromises their survival and leads to reduced numbers of AMs in the lung. Using RNA sequencing, lipidomics and multiparameter flow cytometry, we demonstrate that CD44^−/− mice have impaired AM lipid homeostasis and increased surfactant lipids in the lung. CD44^−/− AMs had increased expression of CD36, a lipid scavenger receptor, as well as increased intracellular lipid droplets, giving them a foamy appearance. RNA sequencing revealed the differential expression of genes associated with lipid efflux and metabolism in CD44^−/− AMs. Lipidomic analysis showed increased lipids in both the supernatant and cell pellet extracted from the bronchoalveolar lavage of CD44^−/− mice. Phosphatidylcholine species, cholesterol, oxidized phospholipids and levels of reactive oxygen species (ROS) were increased in CD44^−/− AMs. Oxidized phospholipids were more cytotoxic to CD44^−/− AMs and induced greater lung inflammation in CD44^−/− mice. Reconstitution of CD44^+/+ mice with CD44^−/− bone marrow as well as adoptive transfer of CD44^−/− AMs into CD44^+/+ mice showed that lipid accumulation in CD44^−/− AMs occurred irrespective of the lung environment, suggesting a cell intrinsic defect. Administration of colony stimulating factor 2 (CSF-2), a critical factor in AM development and maintenance, increased AM numbers in CD44^−/− mice and decreased phosphatidylcholine levels in the bronchoalveolar lavage, but was unable to decrease intracellular lipid accumulation in CD44^−/− AMs. Peroxisome proliferator-activated receptor gamma (PPARγ), downstream of CSF-2 signaling and a regulator of lipid metabolism, was reduced in the nucleus of CD44^−/− AMs, and PPARγ inhibition in normal AMs increased their lipid droplets. Thus, CD44 deficiency causes defects in AMs that lead to abnormal lipid accumulation and oxidation, which exacerbates oxidized lipid-induced lung inflammation. Collectively, these findings implicate CD44 as a regulator of lung homeostasis and inflammation.

Eucalyptol reduces airway hyperresponsiveness in rats following cigarette smoke-exposed

BACKGROUND

Cigarette smoke is the major cause of airway inflammatory disease, including airway hyperresponsiveness. Eucalyptol (EUC), also named 1.8-cineole, is a monoterpenoid found in essential oil of medicinal plants, showing several biological effects.

HYPOTHESIS/PURPOSE

Based in the eucalyptol protective activity in respiratory diseases as asthma, our hypothesis is that eucalyptol is able to reduce the airway hyperresponsiveness and the respiratory mechanic parameters in rats exposed to cigarette smoke.

STUDY DESIGN

Wistar rats were divided into control and cigarettes smoke (CS) groups. CS group was daily subjected to cigarette smoke and treated by inhalation for 15 min/day with EUC (1 mg/mL) or vehicle during 30 days. After treatment, bronchoalveolar lavage (BAL) was collected to analyze the inflammatory profile, and tracheal rings were isolated for evaluation of the airway smooth muscle hyperresponsiveness. Lung function was analyzed in vivo.

METHODS

The inflammatory profile was evaluated by optical microscopy performing total (Neubauer chamber) and differential leukocyte count (smear slides stained in H&E). The hyperresponsiveness was evaluated in tracheal rings contracted with potassium chloride (KCl) carbamoylcholine (CCh), or Barium chloride (BaCl₂) in presence or absence of nifedipine. The lung function (Newtonian resistance-R_N) was evaluated by bronco stimulation with methacholine (MCh).

RESULTS

BAL from CS group increased the influx of leukocyte, mainly neutrophils and macrophages compared to control group. EUC reduced by 71% this influx. The tracheal contractions induced by KCl, CCh or BaCl₂ were reduced by EUC in 59%, 42% and 26%, respectively. The last one was not different of nifedipine activity. Newtonian resistance (R_N) was also reduced in 37% by EUC compared to CS group. 
 CONCLUSION: EUC reduces the hyperresponsiveness and the airway inflammatory profile, recovering the lung function.

Biotransformation of Piceatannol, a Dietary Resveratrol Derivative: Promises to Human Health

SCOPE

To evaluate the health-promoting potentials of piceatannol (PIC), a dietary resveratrol derivative, its biotransformation is examined.

METHODS AND RESULTS

The biotransformation is tested in human/rat hepatic microsomes and cytosols; its pharmacokinetic profiles are assessed in rats. Although limited phase I metabolism exists in microsomes, PIC is rapidly converted to two pharmacologically active metabolites, namely rhapontigenin (RHA) and isorhapontigenin (ISO) in cytosols. Such biotransformation is completely blocked by entacapone, a well-known catechol-O-methyltransferase (COMT) inhibitor, demonstrating that the O-methylation is mediated by COMT. Moreover, PIC is identified as a substrate inhibitor of COMT, suggesting its potential benefits in Alzheimer's disease. Due to extensive phase II metabolism including glucuronidation, sulfation, and O-methylation, PIC displays rapid clearance and at least 4.02% ± 0.61% and 17.70% ± 0.91% of PIC is converted to RHA and ISO, respectively, in rats after intravenous administration. Similarly, PIC serves as an effective precursor of ISO upon oral administration.

CONCLUSION

Since PIC and its metabolites possess pleiotropic health-promoting activities, it has emerged as a promising nutraceutical candidate for further development. This study also reinforces the importance of in vivo testing in nutritional researches as the active metabolite(s) may be absent from the in vitro system.

TGF-β3 Induces Autophagic Activity by Increasing ROS Generation in a NOX4-Dependent Pathway

Higher concentrations of reactive oxygen species (ROS) have been associated with epithelial cell damage, cell shedding, and airway hyperresponsiveness. Previous studies have indicated that transforming growth factor-beta (TGF-β) mediates ROS production and NADPH oxidase (NOX) activity. In our previous study, we also observed that TGF-β3 increases mucus secretion in airway epithelial cells in an autophagy-dependent fashion. Although it is well known that the relationship between ROS and autophagy is cell context-dependent, the exact mechanism of action remains unclear. The following study examined whether ROS act as upstream of autophagy activation in response to TGF-β3 induction. Using an allergic inflammation mouse model induced by house dust mite (HDM), we observed elevated lung amounts of TGF-β3 accompanied by increased ROS levels. And we found that ROS levels were elevated and NOX4 expression was increased in TGF-β3-induced epithelial cells, while the lack of NOX4 in the epithelial cells could reduce ROS generation and autophagy-dependent MUC5AC expression treated with TGF-β3. Furthermore, our studies demonstrated that the Smad2/3 pathway was involved in TGF-β3-induced ROS generation by promoting NOX4 expression. The inhibition of ROS generation by N-Acetyl-L-cysteine (NAC) resulted in a decrease in mucus expression and autophagy activity in vivo as well as in vitro. Finally, TGF-β3-neutralizing antibody significantly reduced the ROS generation, mucus expression, and autophagy activity and also decreased the phosphorylation of Smad2 and Smad3. Taken together, the obtained results revealed that persistent TGF-β3 activation increased ROS levels in a NOX4-dependent pathway and subsequently induced autophagy as well as MUC5AC expression in the epithelial cells.

Potential anti-inflammatory and immunomodulatory effects of carvacrol against ovalbumin-induced asthma in rats

BACKGROUND

Asthma is a complex inflammatory disease which affects multiple individuals worldwide especially pediatric ages.

AIMS

This study aimed to assess the possible protective effect of carvacrol, as natural antioxidant anti-inflammatory drug, against bronchial asthma induced experimentally in rats.

MAIN METHODS

Rats were randomly allocated into 5 groups; a normal control group, control drug group received only carvacrol, an asthma control group, a standard treatment group receiving dexamethasone (DEXA) and carvacrol treatment group. Bronchial asthma was induced by sensitization with i.p dose followed by challenge with intranasal dose of ovalbumin (OVA). 24 h after the last challenge, absolute eosinophil count (AEC) were determined in bronchoalveolar lavage fluids (BALF). Immunoglobulin E (IgE) was determined in serum. Inflammatory biomarkers like Interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin 13 (IL-13), tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) were also measured in BALF. Nitrosative stress biomarker namely inducible nitric oxide synthase (iNOS) was determined in BALF as well as oxidative stress biomarkers namely superoxide dismutase (SOD), glutathione (GSH) and malondialdehyde (MDA) were determined in lung tissue. Additionally, histopathological study, immunohistochemical study of UCN and western blot analysis of SP-D were performed.

KEY FINDINGS

Carvacrol administration significantly reduced the values of AEC, IgE, IL-4, IL-5, IL-13, TNF-α, IFN-γ, iNOS and MDA, while it significantly increased the values of SOD and GSH as compared to the asthmatic group. Histopathological, immunohistochemical and western blot study reinforced the biochemical results.

SIGNIFICANCE

Carvacrol may be a promising protective agent against bronchial asthma induced experimentally in rats.

Mitigation of Hydrochloric Acid (HCl)-Induced Lung Injury in Mice by Aerosol Therapy of Surface-Active Nanovesicles Containing Antioxidant and Anti-inflammatory Drugs

Acute lung injury leading to alveolar inflammation and surfactant dysfunction remains a medical challenge. Surface-active lipid nanovesicles of 200-250 nm size with antioxidant D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS) and anti-inflammatory drug dexamethasone disodium phosphate (DXP) dual combination (Dual-NV) were developed for delivery as aerosols by nebulization in acid lung injury models. Drug deposition studies showed Dual-NV deposited ∼2.5 times more DXP compared to equivalent DXP solution. Nanovesicles are actively internalized by A549 cells through ATP- and clathrin-dependent pathways. The nanovesicles could be phagocytosed by RAW 264.7 macrophages and were nonimmunogenic and did not elicit overproduction of TNF-α, IL-1β, and IL-6. Dual-NV aerosol therapy at 200 mg/kg body weight, in HCl acid-induced lung injury in mice, markedly reduced pulmonary hemorrhage and protein leakage and improved capillary (airway) patency to ∼96%. Dual-NV aerosol therapy also significantly lowered production of inflammatory cytokine IL-1β, IL-6, and TNF-α and reduced oxidative stress by ∼95% in the injured group. Surface-active Dual-NV aerosol therapy is promising for replenishing the dysfunctional surfactant pool and mitigating inflammation and oxidative stress in lung injuries.

The influence of weather and climate on patients with respiratory diseases in Vladivostok as a global health implication

PURPOSE

To identify the formation of meteopathic reactions in patients with respiratory diseases under the influence of extreme weather changes in Vladivostok.

METHODS

The short-term meteopathic reaction in patients with respiratory diseases to the impact of "Weather Complex", consisting of nine weather parameters, on the day of patient's examination and on 1 and 2 days before the examination, was assessed. 146 acclimatized residents of Vladivostok (29 patients with chronic bronchitis, 51 patients with controlled asthma, 39 patients with uncontrolled asthma and 27 healthy volunteers) were examined. Pulmonary function (PF) was studied by spirography and by body plethysmography.

RESULTS

The adaptive-compensatory response of PF in patients with respiratory diseases to weather decreases depending on the disease severity, resulting in the development of meteodependence. The impact of "Weather Complex" on a human body is primarily reflected in PF, and the reaction of metabolic parameters is manifested with a 1-2 days time lag. Glutathione peroxidase and glutathione reductase, key factors in maintaining oxidative cell balance, play the most important role in the formation of a compensatory response to weather. In the light of the global health implication, recommendations are suggested to adjust the treatment of patients with respiratory pathology in specific conditions of abruptly changeable weather.

CONCLUSIONS

The maritime monsoon climate creates an additional strain on both respiratory system and systems that ensure the peroxidation balance worsening bronchopulmonary pathology.

Impact of electronic cigarette heating coil resistance on the production of reactive carbonyls, reactive oxygen species and induction of cytotoxicity in human lung cancer cells in vitro

Electronic cigarette (e-cigarette; e-cig) use has grown exponentially in recent years despite their unknown health effects. E-cig aerosols are now known to contain hazardous chemical compounds, including carbonyls and reactive oxygen species (ROS), and these compounds are directly inhaled by consumers during e-cig use. Both carbonyls and ROS are formed when the liquid comes into contact with a heating element that is housed within an e-cig's atomizer. In the present study, the effect of coil resistance (1.5 Ω and 0.25 Ω coils, to obtain a total wattage of 8 ± 2 W and 40 ± 5 W, respectively) on the generation of carbonyls (formaldehyde, acetaldehyde, acrolein) and ROS was investigated. The effect of the aerosols generated by different coils on the viability of H1299 human lung carcinoma cells was also evaluated. Our results show a significant (p < 0.05) correlation between the low resistance coils and the generation of higher concentrations of the selected carbonyls and ROS in e-cig aerosols. Moreover, exposure to e-cig vapor reduced the viability of H1299 cells by up to 45.8%, and this effect was inversely related to coil resistance. Although further studies are needed to better elucidate the potential toxicity of e-cig emissions, our results suggest that these devices may expose users to hazardous compounds which, in turn, may promote chronic respiratory diseases.

Reactive Oxygen Species-Dependent Calpain Activation Contributes to Airway and Pulmonary Vascular Remodeling in Chronic Obstructive Pulmonary Disease

Aims: Airway and pulmonary vascular remodeling is an important pathological feature in the pathogenesis of chronic obstructive pulmonary disease (COPD). Tobacco smoke (TS) induces the production of large amounts of reactive oxygen species (ROS) in COPD lungs. We investigated how ROS lead to airway and pulmonary vascular remodeling in COPD. Results: We used in vitro bronchial and pulmonary artery smooth muscle cells (BSMCs and PASMCs), in vivo TS-induced COPD rodent models, and lung tissues of COPD patients. We found that H2O2 and TS extract (TSE) induced calpain activation in BSMCs and PASMCs. Calpain activation was elevated in smooth muscle of bronchi and pulmonary arterioles in COPD patients and TS-induced COPD rodent models. Calpain inhibition attenuated H2O2- and TSE-induced collagen synthesis and proliferation of BSMCs and PASMCs. Exposure to TS causes increases in airway resistance, right ventricular systolic pressure (RVSP), and thickening of bronchi and pulmonary arteries. Calpain inhibition by smooth muscle-specific knockout of calpain and the calpain inhibitor MDL28170 attenuated increases in airway resistance, RVSP, and thickening of bronchi and pulmonary arteries. Moreover, smooth muscle-specific knockout of calpain did not reduce TS-induced emphysema in the mouse model, but MDL28170 did reduce TS-induced emphysema in the rat model. Innovation: This study provides the first evidence that ROS-induced calpain activation contributes to airway and pulmonary vascular remodeling in TS-induced COPD. Calpain might be a novel therapeutic target for the treatment of COPD. Conclusion: These results indicate that ROS-induced calpain activation contributes to airway and pulmonary vascular remodeling and pulmonary hypertension in COPD.

Protein carbonylation in human bronchial epithelial cells exposed to cigarette smoke extract

Cigarette smoke is a well-established exogenous risk factor containing toxic reactive molecules able to induce oxidative stress, which in turn contributes to smoking-related diseases, including cardiovascular, pulmonary, and oral cavity diseases. We investigated the effects of cigarette smoke extract on human bronchial epithelial cells. Cells were exposed to various concentrations (2.5-5-10-20%) of cigarette smoke extract for 1, 3, and 24 h. Carbonylation was assessed by 2,4-dinitrophenylhydrazine using both immunocytochemical and Western immunoblotting assays. Cigarette smoke induced increasing protein carbonylation in a concentration-dependent manner. The main carbonylated proteins were identified by means of two-dimensional electrophoresis coupled to MALDI-TOF mass spectrometry analysis and database search (redox proteomics). We demonstrated that exposure of bronchial cells to cigarette smoke extract induces carbonylation of a large number of proteins distributed throughout the cell. Proteins undergoing carbonylation are involved in primary metabolic processes, such as protein and lipid metabolism and metabolite and energy production as well as in fundamental cellular processes, such as cell cycle and chromosome segregation, thus confirming that reactive carbonyl species contained in cigarette smoke markedly alter cell homeostasis and functions.

Oxidative CaMKII as a potential target for inflammatory disease (Review)

CaMKII is a calcium‑activated kinase, proved to be modulated by oxidation. Currently, the oxidative activation of CaMKII exists in several models of asthma, chronic rhinosinusitis with nasal polyps, cardiovascular disease, diabetes mellitus, acute ischemic stroke and cancer. Oxidized CaMKII (ox‑CaMKII) may be important in several of these diseases. The present review examines the mechanism underlying the oxidative activation of CaMKII and summarizes the current findings associated with the function of ox‑CaMKII in inflammatory diseases. Taken together, the findings of this review aim to improve current understanding of the function of ox‑CaMKII and provide novel insights for future research.

Xanthine oxidase activity in type 2 diabetic Nigerians

AIM

This study evaluated the activity of xanthine oxidase in Nigerians with type 2 diabetic mellitus as well as its relationship with lipid peroxidation, inflammatory bio markers and glycemic control indices.

METHODS

Two hundred and thirty seven (237) subjects, comprising of one hundred and fifty seven (157) DM subjects and eighty (80) aged matched controls participated in this study. Blood samples were collected from the participants for the estimations of xanthine oxidase activity, uric acid, malon diadehyde (MDA), erythrocyte sedimentation rate (ESR), high sensitive c - reactive protein (hs CRP), glucose, fructosamine and glycosylated hemoglobin by standard methods.

RESULTS

The results of this study showed a significantly increased activity of xanthine oxidase in DM (0.044 ± 0.05μ/mg) compared with apparently healthy controls (0.028 ± 0.00 μ/mg). The mean plasma levels of MDA (42.40 ± 2.50μmol/l) and uric acid (7.22 ± 0.20 mg/dl) in DM were significantly higher (p ≤ 0.05) than healthy non DM group. The mean levels of hs CRP in DM (4.09 ± 0.91μg/ml) was significantly higher than controls (1.30 ± 0.50μg/ml, p = 0.009). While no association of xanthine oxidase was observed with glycemic control indices and hs CRP, a negative association of xanthine oxidase was observed with MDA (r = -0.514, p = 0.000).

CONCLUSION

Increased activity of xanthine oxidase in DM was associated with increased lipid peroxidation and could be a salient entity towards the onset on complications.

Eucalyptol promotes lung repair in mice following cigarette smoke-induced emphysema

BACKGROUND

Eucalyptol is a monoterpenoid oil present in many plants, principally the Eucalyptus species, and has been reported to have anti-inflammatory and antioxidative effects.

HYPOTHESIS/PURPOSE

Since the potential effect of eucalyptol on mouse lung repair has not yet been studied, and considering that chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide, the aim of this study was to investigate eucalyptol treatment in emphysematous mice.

STUDY DESIGN

Male mice (C57BL/6) were divided into the following groups: control (sham-exposed), cigarette smoke (CS) (mice exposed to 12 cigarettes a day for 60 days), CS + 1 mg/ml (CS mice treated with 1 mg/ml eucalyptol for 60 days), and CS + 10 mg/ml (CS mice treated with 10 mg/ml eucalyptol for 60 days). Mice in the CS and control groups received vehicle for 60 days. Eucalyptol (or the vehicle) was administered via inhalation (15 min/daily). Mice were sacrificed 24 h after the completion of the 120-day experimental procedure.

METHODS

Histology and additional lung morphometric analyses, including analysis of mean linear intercept (Lm) and volume density of alveolar septa (Vv[alveolar septa]) were performed. Biochemical analyses were also performed using colorimetric assays for myeloperoxidase (MPO), malondialdehyde (MDA), and superoxide dismutase (SOD) activity, in addition to using ELISA kits for the determination of inflammatory marker levels (tumor necrosis factor alpha [TNF-α], interleukin-1 beta [IL-1β], interleukin 6 [IL-6], keratinocyte chemoattractant [KC], and tumor growth factor beta 1 [TGF-β1]). Finally, we investigated protein levels by western blotting (nuclear factor (erythroid-derived 2)-like 2 [Nrf2], nuclear factor kappa B [NF-κB], matrix metalloproteinase 12 [MMP-12], tissue inhibitor of matrix metalloproteinase 1 [TIMP-1], neutrophil elastase [NE], and elastin).

RESULTS

Eucalyptol promoted lung repair at the higher dose (10 mg/ml), with de novo formation of alveoli, when compared to the CS group. This result was confirmed with Lm and Vv[alveolar septa] morphometric analyses. Moreover, collagen deposit around the peribronchiolar area was reduced with eucalyptol treatment when compared to the CS group. Eucalyptol also reduced all inflammatory (MPO, TNF-α, IL-1β, IL-6, KC, and TGF-β1) and redox marker levels (MDA) when compared to the CS group (at least p < 0.05). In general, 10 mg/ml eucalyptol was more effective than 1 mg/ml and, at both doses, we observed an upregulation of SOD activity when compared to the CS group (p < 0.001). Eucalyptol upregulated elastin and TIMP-1 levels, and reduced neutrophil elastase (NE) levels, when compared to the CS group.

CONCLUSION

In summary, eucalyptol promoted lung repair in emphysematous mice and represents a potential therapeutic phytomedicine in the treatment of COPD.

Phosphodiesterases as therapeutic targets for respiratory diseases

Chronic respiratory diseases, such as chronic obstructive pulmonary disease (COPD) and asthma, affect millions of people all over the world. Cyclic adenosine monophosphate (cAMP) which is one of the most important second messengers, plays a vital role in relaxing airway smooth muscles and suppressing inflammation. Given its vast role in regulating intracellular responses, cAMP provides an attractive pharmaceutical target in the treatment of chronic respiratory diseases. Phosphodiesterases (PDEs) are enzymes that hydrolyze cyclic nucleotides and help control cyclic nucleotide signals in a compartmentalized manner. Currently, the selective PDE4 inhibitor, roflumilast, is used as an add-on treatment for patients with severe COPD associated with bronchitis and a history of frequent exacerbations. In addition, other novel PDE inhibitors are in different phases of clinical trials. The current review provides an overview of the regulation of various PDEs and the potential application of selective PDE inhibitors in the treatment of COPD and asthma. The possibility to combine various PDE inhibitors as a way to increase their therapeutic effectiveness is also emphasized.

Combination Therapy with Curcumin Alone Plus Piperine Ameliorates Ovalbumin-Induced Chronic Asthma in Mice

Allergic asthma is an inflammatory condition accompanied by inflammation as well as oxidative stress. Supplementation of an anti-inflammatory agent having antioxidant properties may have therapeutic effects against this disease. Over the recent decades, the interest in combination therapy as new alternative medication has increased and it offers numerous benefits along with noticeable lack of toxicity as well as side effects. In this study, protective effects of curcumin alone and in combination with piperine were evaluated in mouse model of allergic asthma. Balb/c mice were sensitized on days 0, 7, and 14 and challenged from days 16-30 on alternate days with ovalbumin (OVA). Mice were pretreated with curcumin (Cur; 10 and 20 mg/kg) and piperine (Pip; 5 mg/kg) alone and in combination via the intraperitoneal route on days 16-30 and compared with intranasal curcumin (5 mg/kg) treatment. Blood, bronchoalveolar lavage fluid (BALF), and lungs were collected after mice were sacrificed on day 31st. Mice immunized with OVA have shown significant increase in airway inflammation and oxidative stress as determined by oxidative stress markers. A significant suppression was observed with all the treatments, but intranasal curcumin treatment group has shown maximum suppression. So, among all the treatment strategies utilized, intranasal curcumin administration was most appropriate in reducing inflammation and oxidative stress and possesses therapeutic potential against allergic asthma. Present study may prove the possibility of development of curcumin nasal drops towards treatment of allergic asthma.

Oxidative Stress and Neonatal Respiratory Extracorporeal Membrane Oxygenation

Oxidative stress is a frequent condition in critically ill patients, especially if exposed to extracorporeal circulation, and it is associated with worse outcomes and increased mortality. The inflammation triggered by the contact of blood with a non-endogenous surface, the use of high volumes of packed red blood cells and platelets transfusion, the risk of hyperoxia and the impairment of antioxidation systems contribute to the increase of reactive oxygen species and the imbalance of the redox system. This is responsible for the increased production of superoxide anion, hydrogen peroxide, hydroxyl radicals, and peroxynitrite resulting in increased lipid peroxidation, protein oxidation, and DNA damage. The understanding of the pathophysiologic mechanisms leading to redox imbalance would pave the way for the future development of preventive approaches. This review provides an overview of the clinical impact of the oxidative stress during neonatal extracorporeal support and concludes with a brief perspective on the current antioxidant strategies, with the aim to focus on the potential oxidative stress-mediated cell damage that has been implicated in both short and long-term outcomes.

Effect of Charcoal in Cigarette Filters on Free Radicals in Mainstream Smoke

The addition of charcoal in cigarette filters may be an effective means of reducing many toxicants from tobacco smoke. Free radicals are a highly reactive class of oxidants abundant in cigarette smoke, and here we evaluated the effectiveness of charcoal to reduce free radical delivery by comparing radical yields from commercially available cigarettes with charcoal-infused filters to those without and by examining the effects of incorporating charcoal into conventional cigarette filters on radical production. Commercial cigarettes containing charcoal filters produced 40% fewer gas-phase radicals than did regular cellulose acetate filter cigarettes when smoked using the International Organization of Standardization (ISO, p = 0.07) and Canadian Intense (CI, p < 0.01) smoking protocols. While mean-particulate-phase radicals were 25-27% lower in charcoal cigarettes, differences from noncharcoal products were not significant ( p = 0.06-0.22). When cellulose acetate cigarette filters were modified to incorporate different types and amounts of activated charcoal, reductions in gas-phase (>70%), but not particulate-phase, radicals were observed. The reductions in gas-phase radicals were similar for the three types of charcoal. Decreases in radical production were dose-responsive with increasing amounts of charcoal (25-300 mg) with as little as 25 mg of activated charcoal reducing gas-phase radicals by 41%. In all studies, charcoal had less of an effect on nicotine delivery, which was decreased 33% at the maximal amount of charcoal tested (300 mg). Overall, these results support the potential consideration of charcoal in cigarette filters as a means to reduce exposure to toxic free radicals from cigarettes and other combustible tobacco products.