Effects of cigarette smoke on degranulation and NO production by mast cells and epithelial cells

Exhaled nitric oxide levels in COPD patients who use electronic cigarettes

Emerging data from clinical studies have shown pro-inflammatory effects associated with e-cigarette use. Fractional exhaled nitric oxide (FeNO) is a biomarker of pulmonary type 2 (T2) inflammation. The effect of chronic e-cigarette use on FeNO is unclear. The aim of this study was to compare FeNO levels in COPD ex-smokers who use e-cigarettes (COPDE + e-cig) to COPDE ex-smokers (COPDE) and COPD current smokers (COPDS). FeNO levels were significantly higher in COPDE + e-cig (median 16.2 ppb) and COPDE (median 18.0 ppb) compared to COPDS (median 7.6 ppb) (p = 0.0003 and p < 0.0001 respectively). There was no difference in FeNO levels between COPDE + e-cig compared to COPDE (p > 0.9). The importance of our results is that electronic cigarette use does not alter the interpretation of FeNO results, and so does not interfere with the use of FeNO as a practical biomarker of T2 inflammation, unlike current cigarette smoking in COPD. Whilst the effect of electronic cigarette use on FeNO levels is not the same as cigarette smoke, this cannot be taken as evidence that electronic cigarettes are harmless. These differential pulmonary effects can be attributed to differences in the chemical composition of the two products.

Association between Plasmodium Infection and Nitric Oxide Levels: A Systematic Review and Meta-Analysis

Nitric oxide (NO) has been implicated in the pathology of malaria. This systematic review and meta-analysis describe the association between NO levels and malaria. Embase, Ovid, PubMed, Scopus, and Google Scholar were searched to identify studies evaluating NO levels in malaria patients and uninfected controls. Meta-regression and subgroup analyses were conducted to discern differences in NO levels between the groups. Of the 4517 records identified, 21 studies were included in the systematic review and meta-analysis. The findings illustrated significant disparities in NO levels based on geographic location and study time frames. Despite the fluctuations, such as higher NO levels in adults compared to children, no significant differences in mean NO levels between patients and uninfected controls (p = 0.25, Hedge's g: 0.35, 95% confidence interval (CI): -0.25-0.96, I2: 97.39%) or between severe and non-severe malaria cases (p = 0.09, Hedge's g: 0.71, 95% CI: -0.11-1.54, I2: 96.07%) were detected. The systematic review and meta-analysis highlighted inconsistencies in NO levels in malaria patients. Given the high heterogeneity of the results, further studies using standardized metrics for NO measurements and focusing on biochemical pathways dictating NO responses in malaria are imperative to understand the association between NO and malaria.

Taxifolin Suppresses Inflammatory Responses of High-Glucose-Stimulated Mouse Microglia by Attenuating the TXNIP-NLRP3 Axis

Type 2 diabetes mellitus is associated with an increased risk of dementia, potentially through multifactorial pathologies, including neuroinflammation. Therefore, there is a need to identify novel agents that can suppress neuroinflammation and prevent cognitive impairment in diabetes. In the present study, we demonstrated that a high-glucose (HG) environment elevates the intracellular reactive oxygen species (ROS) levels and triggers inflammatory responses in the mouse microglial cell line BV-2. We further found that thioredoxin-interacting protein (TXNIP), a ROS-responsive positive regulator of the nucleotide-binding oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, was also upregulated, followed by NLRP3 inflammasome activation and subsequent interleukin-1beta (IL-1β) production in these cells. Conversely, caspase-1 was not significantly activated, suggesting the involvement of noncanonical pathways in these inflammatory responses. Moreover, our results demonstrated that taxifolin, a natural flavonoid with antioxidant and radical scavenging activities, suppressed IL-1β production by reducing the intracellular ROS levels and inhibiting the activation of the TXNIP-NLRP3 axis. These findings suggest the novel anti-inflammatory effects of taxifolin on microglia in an HG environment, which could help develop novel strategies for suppressing neuroinflammation in diabetes.

PI3K signalling in chronic obstructive pulmonary disease and opportunities for therapy

Chronic obstructive pulmonary disease (COPD) is a chronic lung disease characterised by airway inflammation and progressive obstruction of the lung airflow. Current pharmacological treatments include bronchodilators, alone or in combination with steroids, or other anti-inflammatory agents, which have only partially contributed to the inhibition of disease progression and mortality. Therefore, further research unravelling the underlying mechanisms is necessary to develop new anti-COPD drugs with both lower toxicity and higher efficacy. Extrinsic signalling pathways play crucial roles in COPD development and exacerbations. In particular, phosphoinositide 3-kinase (PI3K) signalling has recently been shown to be a major driver of the COPD phenotype. Therefore, several small-molecule inhibitors have been identified to block the hyperactivation of this signalling pathway in COPD patients, many of them showing promising outcomes in both preclinical animal models of COPD and human clinical trials. In this review, we discuss the critically important roles played by hyperactivated PI3K signalling in the pathogenesis of COPD. We also critically review current therapeutics based on PI3K inhibition, and provide suggestions focusing on PI3K signalling for the further improvement of the COPD phenotype. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Impact of fossil fuel emissions and particulate matter on pulmonary health

In recent decades, several national and international legislative efforts have aimed to improve air quality standards and limit major pollutants, such as carbon monoxide, sulfur dioxide, and nitrogen dioxide, linked to several public health problems. In recent years, particulate matter sources have become an important cause of several pulmonary and systemic diseases. Specifically, several studies examining cigarette smoke particulates have discovered the important contribution that mast cells play in the pathogenesis and progression of smoking-related lung disease and other particulate matter-related lung injury. By understanding the mechanisms of activation and signaling cascades involved in cigarette smoke and mast cell activation, novel pharmacological therapies for particulate matter-induced lung diseases could be developed.

Respiratory Protection Behavior and Respiratory Indices among Poultry House Workers on Small, Family-Owned Farms in North Carolina: A Pilot Project

The aim of this pilot study was to evaluate respiratory behavior and respiratory indices of poultry workers on family-owned, poultry farms with 10 or less employees in North Carolina. A field study was conducted to collect data on participants (N = 24) using spirometry, fractional exhaled nitric oxide (Feno), and an interviewer-administered questionnaire. The majority of workers (76%) ranked respiratory protection as being important, yet 48% reported never or rarely wearing respiratory protection when working in dusty conditions. A large percent of workers reported eye (55%) and nasal (50%) irritation and dry cough (50%). On average, pulmonary lung function and Feno tests were normal among nonsmokers. In bivariate analysis, significant associations were identified between working 7 days on the farm (P = .01), with eye irritation, and working 5 or fewer years in poultry farming (P = .01). Poultry workers on family-owned farms spend a considerable amount of work time in poultry houses and report acute respiratory-related health symptoms. Administrative controls among small, family-owned poultry farms are necessary to improve and promote safety and health to its employees.

Effect of nanoparticles exposure on fractional exhaled nitric oxide (FENO) in workers exposed to nanomaterials

Fractional exhaled nitric oxide (FENO) measurement is a useful diagnostic test of airway inflammation. However, there have been few studies of FENO in workers exposed to nanomaterials. The purpose of this study was to examine the effect of nanoparticle (NP) exposure on FENO and to assess whether the FENO is increased in workers exposed to nanomaterials (NM). In this study, both exposed workers and non-exposed controls were recruited from NM handling plants in Taiwan. A total of 437 subjects (exposed group = 241, non-exposed group = 196) completed the FENO and spirometric measurements from 2009–2011. The authors used a control-banding (CB) matrix to categorize the risk level of each participant. In a multivariate linear regression analysis, this study found a significant association between risk level 2 of NP exposure and FENO. Furthermore, asthma, allergic rhinitis, peak expiratory flow rate (PEFR), and NF-κB were also significantly associated with FENO. When the multivariate logistic regression model was adjusted for confounders, nano-TiO₂ in all of the NM exposed categories had a significantly increased risk in FENO > 35 ppb. This study found associations between the risk level of NP exposure and FENO (particularly noteworthy for Nano-TiO₂). Monitoring FENO in the lung could open up a window into the role nitric oxide (NO) may play in pathogenesis.

Normal values and thresholds for the clinical interpretation of exhaled nitric oxide levels in the US general population: results from the National Health and Nutrition Examination Survey 2007-2010

BACKGROUND

Elevated fractional excretion of exhaled nitric oxide (FENO) reflects airway inflammation, but few studies have established its normal values. This study aims to establish the normal values and thresholds for the clinical interpretation of FENO in the US general population.

METHODS

Thirteen thousand two hundred seventy-five subjects aged 6 to 80 years sampled for the National Health and Nutrition Examination Survey (NHANES) 2007-2010 underwent interviews, physical examination, and FENO analysis at 50 mL/s using an online chemiluminescence device according to American Thoracic Society/European Respiratory Society guidelines. After excluding subjects with self-reported asthma and subjects with wheeze in the prior 12 months, prediction equations for the natural logarithm (ln) of FENO were constructed using age, sex, ethnicity, height, BMI, active/passive smoke exposure, and hay fever episodes as covariates.

RESULTS

The fifth to 95th percentile values of FENO were 3.5 to 36.5 parts per billion (ppb) for children < 12 years of age and 3.5 to 39 ppb for subjects 12 to 80 years of age. Using multiple linear regression, prediction equations explained only 10.3% to 15.7% of the variation in the general population. In the general population, 39% to 45% had ln(FENO) levels > 2 SD of the predicted means. When applied to the general population inclusive of subjects who reported asthma but who did not have attacks within the past year, nearly identical results were obtained.

CONCLUSIONS

Assuming 95% of the healthy US general population had no clinically significant airway inflammation as assessed by FENO, values exceeding the 95th percentiles indicated abnormality and a high risk of airway inflammation. A large variation of normal FENO values existed in the general population, which was poorly predicted by multiple linear regression models.

High-risk human papillomavirus-induced expression of endothelial and inducible nitric oxide synthase in human uterine cervix

INTRODUCTION

Levels of nitric oxide metabolites are elevated in the cervical fluid of women with high-risk human papillomavirus (hrHPV). To elucidate the origin of this elevation we studied the cervical expression and localization of endothelial and inducible nitric oxide synthases (eNOS, iNOS) in women.

MATERIAL AND METHODS

Expression of eNOS and iNOS was studied by Western blotting in the uterine cervixes of 86 women with (n = 41) and without (n = 45) hrHPV infection. The localization of eNOS and iNOS in cervical cells was studied by immunohistochemistry in 32 randomly selected women.

RESULTS

Expression of eNOS and iNOS (in mean [95% CI] density units relative to actin) was higher in women with hrHPV versus those without (eNOS: 33.8 [22.5-45.1] versus 20.2 [6.1-34.3], P = 0.007; iNOS: 12.0 [7.1-16.9]) versus 5.6 [2.0-9.2], P = 0.003). Smoking reduced 64% eNOS (P = 0.001) and 68% iNOS (P = 0.008) in women with hrHPV. Endothelial NOS was localized in the vascular endothelium, while iNOS was present in basal squamous epithelial cells. Low-grade histological lesions were accompanied by elevated expression of both eNOS and iNOS.

CONCLUSIONS

High-risk HPV-associated elevation in cervical fluid nitric oxide metabolites results from both eNOS and iNOS stimulation. However, smoking seems to suppress this stimulation in hrHPV-infected women.

A relation between TGF-β and mast cell tryptase in experimental emphysema models

Chronic obstructive pulmonary disease (COPD) is a multicomponent disease characterized by emphysema and/or chronic bronchitis. The aim of this study was to investigate the effect of cigarette smoke exposure on mast cells and mast cell function in vitro and in vivo in order to get further insight in the role of mast cells in the pathogenesis of emphysema. Cigarette smoke conditioned medium (CSM) induced the expression of mast cell tryptase (MMCP-6) in primary cultured mast cells. This tryptase expression was caused by the CSM-stimulated production of TGF-β in culture and neutralization of TGF-β suppressed the CSM-induced expression of tryptase in mast cells. An increase in mast cell tryptase expression was also found in an experimental model for emphysema. Exposure of mice to cigarette smoke increased the number of mast cells in the airways and the expression of mast cell tryptase. In accordance with the in vitro findings, TGF-β in bronchoalveolar lavage fluid of smoke-exposed animals was significantly increased. Our study indicates that mast cells may be a source of TGF-β production after cigarette smoke exposure and that in turn TGF-β may change the tryptase expression in mast cells.

Mast cells and COPD

The pathogenesis of chronic obstructive pulmonary disease (COPD) is based on the innate and adaptive inflammatory immune response to the inhalation of toxic particles and gases. Although tobacco smoking is the primary cause of this inhalation injury, many other environmental and occupational exposures contribute to the pathology of COPD. The immune inflammatory changes associated with COPD are linked to a tissue-repair and -remodeling process that increases mucus production and causes emphysematous destruction of the gas-exchanging surface of the lung. The common form of emphysema observed in smokers begins in the respiratory bronchioles near the thickened and narrowed small bronchioles that become the major site of obstruction in COPD. The inflamed airways of COPD patients contain several inflammatory cells including neutrophils, macrophages, T lymphocytes, and dendritic cells. The relative contribution of mast cells to airway injury and remodeling is not well documented. In this review, an overview is given on the possible role of mast cells and their mediators in the pathogenesis of COPD. Activation of mast cells and mast cell signaling in response to exposure to cigarette smoke is further discussed.

L-arginine reverses cigarette-induced reduction of fractional exhaled nitric oxide in asthmatic smokers

INTRODUCTION

Complex mechanisms regulate nitric oxide (NO) synthesis. Cigarette smoking decreases fractional exhaled NO (FE(NO)), while asthmatic inflammation increases FE(NO). To assess whether the smoking-induced decrease in FE(NO) levels was reversible, asthmatic and non-asthmatic smokers inhaled the NO synthase (NOS) substrate, L-arginine. Aminoguanidine, a relatively selective Type II NOS inhibitor, was used also to assess the role of NOS subtypes in these changes of FE(NO).

METHODS

The study was a single-blinded, placebo-controlled, cross-over design in two parts. Part I: smoking asthmatic and non-asthmatic smoking subjects smoked one cigarette and then inhaled nebulised L-arginine or L-alanine (control). Spirometry, FE(NO), nasal NO (FN(NO)), FE(CO), were measured for 4 h. Part II: subjects inhaled nebulised aminoguanidine prior to an identical protocol as in Part I. Change in FE(NO) was assessed as area under the curve (AUC).

RESULTS

Part I: In asthmatic smokers, cigarette smoking followed by L-arginine caused a significant median increase in AUC of 29.2(17)% FE(NO) change/hour (p = 0.04), which did not occur in non-asthmatic smokers (baseline FE(NO) 12.7(7.1-18) vs. 6.7(4-9.2) ppb, respectively). Part II: Aminoguanidine prior to smoking caused a significant fall in FE(NO) in both asthmatic and non-asthmatic smokers. L-arginine showed significant reversal of this effect in both asthmatic and non-asthmatic subjects.

CONCLUSIONS

In asthmatic smokers, L-arginine increases FE(NO) after cigarette smoking but not in non-asthmatic smokers. The decrease in FE(NO) after aminoguanidine and subsequent partial reversal by L-arginine in both groups, suggests that Type II NOS contributes to the FE(NO) in both.

Cigarette smoke suppresses in vitro allergic activation of mouse mast cells

BACKGROUND

Mast cells are important effector cells in innate or acquired immunity that contribute to host defence. Excessive activation of mast cells can result in the development of allergic diseases, including atopic asthma. Mast cell activation by IgE and specific antigen induces the cells to release spasmogenic, vasoactive and pro-inflammatory mediators, which enhance airway smooth muscle contraction, vascular permeability and inflammatory cell recruitment. Recently, we have demonstrated that exposure of mast cells to cigarette smoke medium (CSM) triggered mast cells to produce chemokines. On the other hand, smoking may decrease the risk of allergic sensitization, which could be explained by a reduced IgE production or a diminished response of mast cells to activation of the IgE receptor.

OBJECTIVE

In this study, we investigated the effect of CSM on the allergic activation of mast cells through IgE and antigen.

METHODS

Primary cultured murine mast cells were exposed to CSM and activated with IgE and antigen or lipopolysaccharide (LPS). The release of granules, production of leukotrienes, chemokines and cytokines was determined in the supernatants by ELISA. The effect of CSM exposure on intracellular signalling, especially the nuclear factor (NF)-kappaB and extracellular signal-regulated kinase (Erk)1/2 pathways, was analysed by Western blotting.

RESULTS

CSM suppressed IgE-mediated degranulation and cytokine release, but no effect was observed on leukotriene release. CSM induced phosphorylation of Erk1/2 in mast cells. In CSM-exposed mast cells, activating transcription factor (ATF)-1 was phosphorylated after stimulation with IgE/Ag. LPS-activated mast cells were not influenced by CSM.

CONCLUSION

Our study suggests that exposure to cigarette smoke may lead to a reduced allergic activation of mast cells without affecting their response to activation via e.g. bacterial-derived LPS.

Ccn2/Ctgf overexpression induced by cigarette smoke during cutaneous wound healing is strain dependent

Cigarette smoke has been associated with poor healing in several studies, but the precise mechanisms involving this impairment are still not elucidated. The aim of this work was to investigate cigarette smoke exposure effects on initial phases of cutaneous healing in mice, focusing mainly on gene expression of two molecules involved in wound repair (Ccn2/Ctgf and Tgfb1) and to study if these effects are strain dependent. Mice were exposed to the smoke of nine cigarettes per day, three times per day, for ten days. In the eleventh day an excisional wound was made. The control group was sham-exposed. The cigarette smoke exposure protocol was performed until euthanasia, seven days after wounding. Wound contraction was evaluated. Sections were stained with hematoxylin-eosin, Sirius red, and toluidine blue, and also immunostained for alpha-smooth muscle actin. Gene expression of Ccn2/Ctgf and Tgfb1 was evaluated by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). Smoke-exposed animals presented delay in wound contraction; fibroblastic, inflammatory, and mast cell recruitment; re-epithelialization; myofibroblastic differentiation; and Ccn2/Ctgf and Tgfb1 gene expression. Those alterations were strain dependent. This work confirmed the deleterious effects of cigarette smoke exposure on mouse cutaneous healing depending on mouse strain and links these effects to an overexpression of Ccn2/Ctgf.

Nitric Oxide and Exhaled Breath Nitrite/Nitrates in Chronic Obstructive Pulmonary Disease Patients

BACKGROUND

Measurement of nitric oxide (NO) and nitrite/nitrates (NOx) levels in exhaled breath condensate (EBC) are non-invasive techniques, which can be used to monitor airway inflammatory diseases. Production of NO is often increased in inflammatory diseases of the airways, including exacerbations of chronic obstructive pulmonary disease (COPD). COPD-associated airway inflammation may be affected by multiple factors, including cigarette smoking and glucocorticosteroid (GCS) treatment.

OBJECTIVES

To test the hypothesis that total NOx levels in EBC and exhaled NO levels would be affected by cigarette smoking or the presence of COPD.

METHODS

Exhaled NO levels and NOx levels in EBC were measured in 96 COPD patients and in 80 normal subjects.

RESULTS

Exhaled NO levels in COPD patients were significantly higher than those of normal subjects when comparing either the total groups (9.8 +/- 0.7 vs. 5.5 +/- 0.4 ppb, p < 0.0005) or 2 appropriate subgroups, ex-smokers (10.3 +/- 1.0 vs. 5.4 +/- 0.6 ppb, p < 0.0005) and smokers (9.2 +/- 1.2 vs. 5.7 +/- 0.5 ppb, p = 0.002). There was no significant difference in NOx levels in EBC, however, between COPD patients and healthy subjects when analysed either together or as subgroups. No significant difference was found in either exhaled NO levels or NOx levels in EBC between GCS-naive subjects and those on GCS treatment in the ex-smoking or smoking COPD subgroups.

CONCLUSIONS

COPD patients have higher exhaled NO levels than control subjects when either combined or analysed as non-smoking, ex-smoking and smoking subgroups. GCS treatment did not appear to affect these non-invasive markers of airway inflammation in COPD.

Exhaled nitric oxide is decreased by exposure to the hyperbaric oxygen therapy environment

Exhaled nitric oxide (eNO) detects airway inflammation. Hyperbaric oxygen therapy (HBOT) is used for tissue hypoxia, but can cause lung damage. We measured eNO following inhalation of oxygen at different tensions and pressures. Methods. Part 1, eNO was measured before and after HBOT. Part 2, normal subjects breathed 40% oxygen. Results. Baseline eNO levels in patients prior to HBOT exposure were significantly higher than in normal subjects (P < .05). After HBOT, eNO significantly decreased in patients (15.4 ± 2.0 versus 4.4 ± 0.5 ppb, P < .001), but not in normal subjects, after either 100% O₂ at increased pressure or 40% oxygen, 1 ATA. In an in vitro study, nitrate/nitrite release decreased after 90 minutes HBOT in airway epithelial (A549) cells. Conclusion. HBO exposure causes a fall in eNO. Inducible nitric oxide synthase (iNOS) may cause elevated eNO in patients secondary to inflammation, and inhibition of iNOS may be the mechanism of the reduction of eNO seen with HBOT.

Smoking habit and load influence age at diagnosis and disease extent in ulcerative colitis

INTRODUCTION

Cigarette smoking affects susceptibility to ulcerative colitis (UC), but its effects on age at diagnosis, disease extent, and need for surgery are less well defined. We examined these parameters in a detailed retrospective analysis of a large cohort of well-characterized UC patients.

METHODS

499 UC patients (254 male, median age 34.3 yr) were studied. Data were collected on smoking habits, smoking load (pack-years), age at recruitment, age at diagnosis, surgery, and disease extent. Colonoscopic and histological data at both diagnosis and follow-up (median follow-up time 4.6 yr) were available on 349 patients.

RESULTS

Ex-smokers were older at diagnosis than current or nonsmokers, (46.5 yr vs 31.1 or 29.4 yr, respectively, P < 0.001). Before diagnosis, ex-smokers had a higher smoking load than current smokers (13.0 vs 6.94 pack-years, P < 0.001). A Cox model for age at diagnosis, with smoking as a time-dependent covariate, showed that at any age, ex-smokers were significantly more likely to develop UC than current smokers (hazard ratio 1.8, 95% CI 1.41-2.44, P < 0.001). For current smokers at latest colonoscopy, those with extensive disease were the lightest smokers (median 0.320 pack-years), whereas those with healthy colons were the heaviest smokers (median 9.18 pack-years, P= 0.006). At 5 yr, regression of extensive disease was more frequent in current than ex-smokers or nonsmokers (30% current smokers vs 8% nonsmokers and 5% ex-smokers, chi(2)= 30.4, P < 0.001) but these differences were not maintained over a longer time period.

CONCLUSIONS

Smoking habit influences the age at diagnosis and changes in disease extent in UC. Mechanisms are likely to be complex and require further investigation.