Cigarette smoke suppresses in vitro allergic activation of mouse mast cells

The impact of smoking and alcohol consumption on rosacea: a multivariable Mendelian randomization study

Backgrounds

Observational studies have shown that cigarette smoking is inversely associated with risk of rosacea, However, it remains uncertain whether this association is causal or it is a result of reverse causation, and whether this association is affected by drinking behaviors.

Methods

This study utilized the summary-level data from the largest genome-wide association study (GWAS) for smoking, alcohol consumption, and rosacea. The objective was to investigate the effect of genetically predicted exposures to smoking and alcohol consumption on the risk of developing rosacea. Two-sample bidirectional Mendelian randomization (MR) was applied, accompanied by sensitive analyses to validate the robustness of findings. Furthermore, multivariable MR was conducted to evaluate the direct impact of smoking on rosacea.

Results

A decreased risk of rosacea was observed in individuals with genetically predicted lifetime smoking [odds ratio (OR)MR - IVW = 0.53; 95% confidence interval (CI), 0.318-0.897; P = 0.017], and number of cigarettes per day (ORMR - IVW = 0.55; 95% CI, 0.358-0.845; P = 0.006). However, no significant associations were found between initiation of regular smoking, smoking cessation, smoking initiation, alcohol consumption and rosacea. Reverse MR analysis did not show any associations between genetic liability toward rosacea and smoking or alcohol drinking. Importantly, the effect of lifetime smoking and the number of cigarettes per day on rosacea remained significant even after adjusting for alcohol consumption in multivariable MR analysis.

Conclusion

Smoking was causally related to a lower risk of rosacea, while alcohol consumption does not appear to be associated with risk of rosacea.

Clinical Response to Low-dose Omalizumab Treatment in Chronic Spontaneous Urticaria: A Retrospective Study of 179 Patients

Omalizumab is effective in chronic spontaneous urticaria unresponsive to antihistamines. Of the licensed dosing schedules, Korean patients prefer a low dose, of 150 mg/month, for financial reasons. However, real-world experiences of low-dose omalizumab consumption have not been reported. The aim of this retrospective study was to assess the treatment outcomes and long-term clinical course of patients with chronic spontaneous urticaria who were treated with low-dose omalizumab. The study included 179 patients aged ≥ 20 years who were treated with omalizumab 150 mg/month for ≥ 12 weeks. Baseline disease activity was mild, moderate, and severe in 54.7%, 35.2%, and 10.1% of patients, respectively. A complete response was observed in 133 patients at 12 weeks, among whom 88 patients showed early responses within 4 weeks. Overall, 158 patients finally achieved a complete response. Multivariate analyses revealed that baseline disease activity is more likely to be mild in patients who experience early and final complete responses. The absence of atopic comorbidities correlated with an early response. Smoking was associated with a final complete response. This study shows that low-dose omalizumab provides favourable treatment outcomes in antihistamine-refractory chronic spontaneous urticaria. Disease severity, atopic comorbidity, and smoking may be predictive factors for studying the response to omalizumab.

Lifetime Smoking and Asthma: A Mendelian Randomization Study

Evidence from clinical and epidemiological studies indicates that asthma is associated with allergic diseases including hay fever, allergic rhinitis, and eczema. Genetic analysis demonstrated that asthma had a positive genetic correlation with allergic diseases. A Mendelian randomization (MR) analysis using the rs16969968 single-nucleotide variant as the instrumental variable indicated that smoking was associated with increased risk of asthma. However, in a different MR analysis, smoking was significantly associated with reduced hay fever and reduced allergic sensitization risk. These findings revealed inconsistencies in the association of smoking with asthma and allergic diseases. Hence, we conducted an updated MR analysis to investigate the causal association between lifetime smoking and asthma risk by using 124 genetic variants as the instrumental variables. No significant pleiotropy was detected using the MR-Egger intercept test. We found that increased lifetime smoking was significantly associated with decreased asthma risk by using the inverse variance weighted (IVW) method (OR = 0.97, 95% CI 0.956-0.986, and P = 1.77E-04), the weighted median regression method (OR = 0.976, 95% CI 0.96-0.994, and P = 8.00E-03), and the MR-Egger method (OR = 0.919, 95% CI 0.847-0.998, and P = 4.5E-02). Importantly, MR pleiotropy residual sum and outlier (MR-PRESSO) MR analysis also indicated a significant association between increased lifetime smoking and decreased asthma risk with OR = 0.971, 95% CI 0.956-0.986, and P = 2.69E-04. After the outlier was removed, MR-PRESSO outlier test further supported the significant association with OR = 0.971, 95% CI 0.959-0.984, P = 1.57E-05.

The Association between Tobacco Smoke and Serum Immunoglobulin E Levels in Korean Adults

Objective Smoking is common in patients with allergic diseases. The aim of this study was to evaluate the cross-sectional association between the current smoking status and total and specific Immunoglobulin E (IgE) levels in Korean adults. Methods Data were obtained from the 2010 Korean National Health and Nutrition Examination Survey, a national cross-sectional study. We analyzed the data of subjects whose smoking status and serum IgE levels were of acceptable quality. Results A total of 1,963 subjects (1,118 never smokers, 340 ex-smokers, and 505 current smokers) were included. The total IgE levels and specific IgE levels to house dust mite Dermatophagoides farinae (Df), cockroach, and dog allergens in never smokers were significantly (p<0.0001) lower than in ex-smokers or current smokers. After adjusting for other variables, current smokers independently had significantly higher levels of total IgE and cockroach-specific IgE than ex-smokers or never smokers. The proportions of subjects with total IgE ≥150 kU/L and specific IgE ≥0.35 kU/L to Df-specific IgE were significantly (p value for trend <0.05) increased in ex-smokers and current smokers. The total IgE levels and IgE levels specific to Df, cockroaches, and dogs significantly (p value for trend <0.05) and proportionally increased with increasing numbers of cigarettes smoked daily. Conclusion Smoking was associated with elevated total IgE levels and IgE levels specific to Df, cockroach, and dog allergens in a cumulative, dose-dependent manner. Furthermore, current smoking status was an independent risk factor for elevated total IgE levels and IgE levels specific to cockroach allergen.

Water-pipe smoke condensate increases the internalization of Mycobacterium Bovis of type II alveolar epithelial cells (A549)

BACKGROUND

Tuberculosis (TB) is a major global health problem, and there is an association between tobacco smoke and TB. Water pipe smoking has become an increasing problem not only in Middle Eastern countries but also globally because users consider it as safer than cigarettes. The presence of high levels of toxic substances in water-pipe smoke may be a predisposing factor that enhances the incidence of pulmonary disorders. For example, uncontrolled macropinocytosis in alveolar epithelial cells following exposure to water-pipe smoke may predispose subjects to pulmonary infection. Here, we studied the effects of water-pipe condense (WPC) on the internalization of Mycobacterium Bovis BCG by macropinocytosis in the alveolar epithelial cell line A549.

METHODS

A549 cells were exposed to WPC (4 mg/ml) for 24, 48, 72 and 96 h. Cell viability was studied using the methyl thiazolyldipenyl-tetrazolium bromide (MTT) reduction assay and proliferation by bromodeoxyUridine (BrdU) incorporation. Cells were exposed to FITC-Dextran (1 mg/ml) (as a control) and FITC-BCG (MOI = 10) for 20 min at 37 °C before cells were collected and the uptake of BCG-FITC determined by flow cytometry. Similar experiments were performed at 4 °C as a control. The Rho-associated protein kinase (ROCK) inhibitor Y-27632 (1 μM) was used to assess the mechanism by which WPC enhanced BCG uptake.

RESULTS

WPC (4 mg/ml) increased the uptake of BCG-FITC after 72 (1.3 ± 0.1 fold, p < 0.05) and 96 (1.4 ± 0.05 fold, p < 0.05) hours. No effect on BCG-FITC uptake was observed at 24 or 48 h. WPC also significantly increased the uptake of FITC-Dextran (2.9 ± 0.3 fold, p < 0.05) after 24 h. WPC significantly decreased cell viability after 24 (84 ± 2%, p < 0.05), 48 (78±, 3%, p < 0.05), 72 (64 ± 2%, p < 0.05) and 96 h (45 ± 2%, p < 0.05). Y-27632 completely attenuated the increased uptake of BCG by WPC. Cell proliferation showed a decreasing trend in a time-dependent manner with WPC exposure.

CONCLUSION

WPC exposure increased epithelial cell endocytosis activity and death as well as enhancing their capacity for macropinocytosis. Our in vitro data indicates possible harmful effects of WPC on the ability of lung epithelial cells to phagocytose mycobacterium.

Cigarette smoke extract-treated mast cells promote alveolar macrophage infiltration and polarization in experimental chronic obstructive pulmonary disease

OBJECTIVE

Cigarette smoking is the main cause of chronic obstructive pulmonary disease (COPD) and may modulate the immune response of exposed individuals. Mast cell function can be altered by cigarette smoking, but the role of smoking in COPD remains poorly understood. The current study aimed to explore the role of cigarette smoke extract (CSE)-treated mast cells in COPD pathogenesis.

METHODS

Cytokine and chemokine expression as well as degranulation of bone marrow-derived mast cells (BMMCs) were detected in cells exposed to immunoglobulin E (IgE) and various doses of CSE. Adoptive transfer of CSE-treated BMMCs into C57BL/6J mice was performed, and macrophage infiltration and polarization were evaluated by fluorescence-activated cell sorting (FACS). Furthermore, a coculture system of BMMCs and macrophages was established to examine macrophage phenotype transition. The role of protease serine member S31 (Prss31) was also investigated in the co-culture system and in COPD mice.

RESULTS

CSE exposure suppressed cytokine expression and degranulation in BMMCs, but promoted the expressions of chemokines and Prss31. Adoptive transfer of CSE-treated BMMCs induced macrophage infiltration and M2 polarization in the mouse lung. Moreover, CSE-treated BMMCs triggered macrophage M2 polarization via Prss31 secretion. Recombinant Prss31 was shown to activate interleukin (IL)-13/IL-13Rα/Signal transducers and activators of transcription (Stat) 6 signaling in macrophages. Additionally, a positive correlation was found between Prss31 expression and the number of M2 macrophages in COPD mice.

CONCLUSION

In conclusion, CSE-treated mast cells may induce macrophage infiltration and M2 polarization via Prss31 expression, and potentially contribute to COPD progression.

Tobacco Smoking as a Risk Factor for Increased Antibiotic Prescription

INTRODUCTION

Antibiotic resistance is rapidly spreading, affecting millions of people and costing billions of dollars. Potential factors affecting antibiotic prescription, such as tobacco use, could dramatically influence this public health crisis. The study determined the magnitude of impact that tobacco use has on antibiotic prescribing patterns.

METHODS

Pooled data were analyzed in 2015 from the 2006-2010 National Ambulatory Medical Care Survey, a cross-sectional survey describing use of ambulatory medical services in the U.S. via healthcare provider-patient encounters. Patients aged >18 years with documented tobacco use status diagnosed with an infection were included (i.e., all encounters in the analysis included an infectious diagnosis of interest). The analytic sample included 8,307 visits, representing 294 million visits nationally.

RESULTS

Half (49.9%) of encounters that included any infection had an antibiotic prescribed. Adjusted odds of receiving antibiotics among current tobacco users was 1.20 (95% CI=1.02, 1.42), and even higher for encounters of respiratory infections (AOR=1.31, 95% CI=1.05, 1.62). Antibiotic prescription rates were lower among patients aged >65 years, those with comorbid asthma or cancer, non-whites, and those covered by Medicaid and higher for primary care physicians.

CONCLUSIONS

Despite lack of evidence-based rationale, among a national sample of patients with an infectious diagnosis, tobacco users had 20%-30% higher odds of receiving antibiotics than non-tobacco users. This is the first U.S. study to quantify the magnitude of this unsubstantiated practice. Prescribers should understand that tobacco use could be associated with higher antibiotic prescription, which may subsequently increase antimicrobial resistance in the community.

Effects of conventional tobacco smoke and nicotine-free cigarette smoke on airway inflammation, airway remodelling and lung function in a triple allergen model of severe asthma

BACKGROUND

Patients with asthma who smoke have reduced lung function, increased exacerbation rates and increased steroid resistance compared to non-smoking asthmatics. In mice, cigarette smoke has been reported to have both pro- and anti-Th2 response effects.

OBJECTIVE

We hypothesized that combining tobacco cigarette smoke (tCS) with allergen exposure increases inflammation, airway remodelling and lung function in mice. To test this hypothesis, we combined a severe triple allergen model with tCS exposure and investigated whether effects were due to Toll-like receptor 4 signalling and/or nicotine and also observed when nicotine-free cigarettes were used.

METHODS

Mice were sensitized with ovalbumin, cockroach and house dust mite allergen in alum followed by intratracheal challenges with allergen twice a week for 6 weeks or additionally exposed to tCS during the allergen challenge period. Nicotine or nicotine-free herbal cigarette smoke was also applied to allergen challenged mice.

RESULTS

tCS significantly reduced eosinophil numbers, IL-4 and IL-5 concentrations in the lung, total and allergen-specific IgE in serum, improved lung function and reduced collagen I levels. With the exception of collagen I all parameters reduced by tobacco cigarette smoke were also reduced in Toll-like receptor 4-deficient mice. Nicotine-free cigarette smoke also had significant anti-inflammatory effects on eosinophils, IL-4 and IL-5 concentrations in the lung and reduced airway hyperreactivity, albeit weaker than tobacco smoke. Applying nicotine alone also reduced Th2 cytokine levels and eosinophil numbers in the airways.

CONCLUSION

Our experiments show that tCS exposure reduces allergen-induced Th2 response in the lung and associated collagen I production and development of airway hyperreactivity. With the exception on collagen I formation, these effects were not dependent on Toll-like receptor 4. The observed anti-Th2 effects of both nicotine and nicotine-free herbal cigarette smoke together suggests that tCS reduces the Th2 responses through nicotine and other products released by burning tobacco.

The effects of alcohol consumption and smoking on allergy risk in Korean adults

BACKGROUND

The immune-modulating effects of alcohol and smoking are well known through a great body of research. Furthermore, many studies have been performed on the influence of alcohol and smoking on the development of allergic disease. However, previous studies have reported conflicting results with associations between alcohol intake or smoking and risk of allergy. The purpose of this study was to evaluate the effects of alcohol consumption and smoking on total serum immunoglobulin E (TIgE) and prevalence of sensitization to Dermatophagoides farinae in a representative sample of Korean adults.

METHODS

TIgE levels and IgE levels specific to D. farinae were measured. Alcohol, smoking habit, and other influencing variables were obtained from the 2010 Korean National Health and Nutrition Examination.

RESULTS

Smoking (smoked five packs or more in lifetime) was independently associated with increased risk of sensitization to D. farinae (odds ratio [OR], 1.439; 95% CI, 1.075-1.927). Frequent alcohol drinking (more than four times a week) also showed similar association when compared with subjects who drank less than once per month (OR, 2.052; 95% CI, 1.257-3.350). TIgE levels were also increased along with increased frequency of alcohol drinking. However, smoking habit was not related to TIgE levels.

CONCLUSION

These findings suggest that history of smoking and frequent alcohol consumption are significantly associated with increased prevalence of sensitization to D. farinae. In addition, frequency of alcohol drinking was also related to a moderate increase in TIgE levels in Korean adults.

Pneumocystis jirovecii colonization in Chronic Obstructive Pulmonary Disease (COPD)

Chronic obstructive pulmonary disease (COPD) is associated with a chronic inflammatory response in airways and lung parenchyma that results in significant morbidity and mortality worldwide. Cigarette smoking considered as an important risk factor plays a role in pathogenesis of disease. Pneumocystis jirovecii is an atypical opportunistic fungus that causes pneumonia in immunosuppressed host, although the low levels of its DNA in patients without signs and symptoms of pneumonia, which likely represents colonization. The increased prevalence of P. jirovecii colonization in COPD patients has led to an interest in understanding its role in the disease. P. jirovecii colonization in these patients could represent a problem for public health since colonized patients could act as a major reservoir and source of infection for susceptible subjects. Using sensitive molecular techniques, low levels of P. jirovecii DNA have been detected in the respiratory tract of certain individuals. It is necessary to elucidate the role of P. jirovecii colonization in the natural history of COPD patients in order to improve the clinical management of this disease. In the current review paper, we discuss P. jirovecii colonization in COPD patients.

Increased numbers of tryptase-positive mast cells in the healthy and sun-protected skin of tobacco smokers

BACKGROUND

Tobacco smoking may cause skin aging through mast cell proteinases.

OBJECTIVE

To compare the numbers of mast cells showing tryptase and chymase in the healthy-looking skin of smokers and non-smokers.

METHODS

The study subjects consisted of 80 males, 42 of whom were smokers and 38 non-smokers. A skin biopsy from the medial arm was processed for immunohistochemical staining of tryptase and chymase, as well as chymase inhibitors alpha-1-proteinase inhibitor (alpha-1-PI) and alpha-1-antichymotrypsin (alpha-1-AC).

RESULTS

The number of tryptase(+) mast cells was significantly higher in the smoker group (84 ± 32 cells/mm(2)) than in the non-smoker group (70 ± 32 cells/mm(2)) (p = 0.044). Likewise, the number of chymase(+) mast cells was higher in the smoker group (89 ± 20 vs. 80 ± 22 cells/mm(2)), though statistical significance was not reached (p = 0.07). No significant difference was observed in alpha-1-PI(+) and alpha-1-AC(+) cells.

CONCLUSION

Especially tryptase, but probably also chymase, may have an influence on the skin of smokers, such as wrinkling and aging.

Tobacco smoke exposure and allergic sensitization in children: a propensity score analysis

BACKGROUND AND OBJECTIVE

There is conflicting evidence of the effect of environmental tobacco smoke (ETS) on the development of allergic diseases in children. Studies have shown that this relationship differs depending on maternal history of the disease. We employed the rigour of propensity score methods to assess this relationship using data from a birth cohort.

METHODS

Using n = 662 children from the Wayne County Health, Environment, Allergy and Asthma Longitudinal Study, we assessed the relationship between early-life ETS and subsequent allergic sensitization via a positive skin prick test (SPT+) or at least one specific immunoglobulin E (IgE) ≥ 0.35 (sIgE+) in children aged 2-3 years. Propensity score estimation followed by full and nearest neighbour matching was compared with standard multivariable regression models.

RESULTS

Among children without a maternal history of allergic disease, ETS was positively associated with allergic sensitization in children with an adjusted odds ratio (aOR) for SPT+ of 2.32 (95% confidence interval (CI): 1.28-4.22) and the aOR for sIgE+ was 2.53 (95% CI: 1.43-4.48). Contrarily, for children with a positive maternal history, the aOR for SPT+ and sIgE+ was 0.56 (95% CI: 0.24-1.32) and 0.43 (95% CI: 0.20-0.91), respectively.

CONCLUSIONS

Using propensity score methods to rigorously control for confounding factors, ETS exposure was found to reduce the risk of allergic sensitization in children with a positive maternal history. There is a strong association between early-life ETS and the development of allergic sensitization for children aged 2-3 years without maternal history.

Cigarette smoke suppresses the surface expression of c-kit and FcεRI on mast cells

Chronic obstructive pulmonary disease (COPD) is a multicomponent disease characterized by emphysema and/or chronic bronchitis. COPD is mostly associated with cigarette smoking. Cigarette smoke contains over 4,700 chemical compounds, including free radicals and LPS (a Toll-Like Receptor 4 agonist) at concentrations which may contribute to the pathogenesis of diseases like COPD. We have previously shown that short-term exposure to cigarette smoke medium (CSM) can stimulate several inflammatory cells via TLR4 and that CSM reduces the degranulation of bone-marrow-derived mast cells (BMMCs). In the current study, the effect of CSM on mast cells maturation and function was investigated. Coculturing of BMMC with CSM during the development of bone marrow progenitor cells suppressed the granularity and the surface expression of c-kit and Fc ε RI receptors. Stimulation with IgE/antigen resulted in decreased degranulation and release of Th1 and Th2 cytokines. The effects of CSM exposure could not be mimicked by the addition of LPS to the culture medium. In conclusion, this study shows that CSM may affect mast cell development and subsequent response to allergic activation in a TLR4-independent manner.

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.

Cigarette smoke exacerbates mouse allergic asthma through Smad proteins expressed in mast cells

Background

Many studies have found that smoking reduces lung function, but the relationship between cigarette smoke and allergic asthma has not been clearly elucidated, particularly the role of mast cells. This study aimed to investigate the effects of smoke exposure on allergic asthma and its association with mast cells.

Methods

BALB/c mice were sensitized and challenged by OVA to induce asthma, and bone marrow-derived mast cells (BMMCs) were stimulated with antigen/antibody reaction. Mice or BMMCs were exposed to cigarette smoke or CSE solution for 1 mo or 6 h, respectively. The recruitment of inflammatory cells into BAL fluid or lung tissues was determined by Diff-Quik or H&E staining, collagen deposition by Sircol assay, penh values by a whole-body plethysmography, co-localization of tryptase and Smad3 by immunohistochemistry, IgE and TGF-β level by ELISA, expressions of Smads proteins, activities of signaling molecules, or TGF-β mRNA by immunoblotting and RT-PCR.

Results

Cigarette smoke enhanced OVA-specific IgE levels, penh values, recruitment of inflammatory cells including mast cells, expressions of smad family, TGF-β mRNA and proteins, and cytokines, phosphorylations of Smad2 and 3, and MAP kinases, co-localization of tryptase and Smad3, and collagen deposition more than those of BAL cells and lung tissues of OVA-induced allergic mice. CSE solution pretreatment enhanced expressions of TGF-β, Smad3, activities of MAP kinases, NF-κB/AP-1 or PAI-1 more than those of activated-BMMCs.

Conclusions

The data suggest that smoke exposure enhances antigen-induced mast cell activation via TGF-β/Smad signaling pathways in mouse allergic asthma, and that it exacerbates airway inflammation and remodeling.

Impact of smoking on inflammation: overview of molecular mechanisms

BACKGROUND

Inflammation is a critical component of normal tissue repair, as well as being fundamental to the body's defense against infection. Environmental factors, such as smoking, have been reported to modify the host response and hence modify inflammation progression, severity and outcome. Therefore, a comprehensive understanding of the molecular mechanisms by which smoking affects inflammation is vital for preventive and therapeutic strategies on a clinical level.

AIM

The purpose of the present article is to review the potential biological mechanisms by which smoking affects inflammation, emphasizing recent developments.

RESULTS

Smoking is reported to effect a number of biological mediators of inflammation through its effect on immune-inflammatory cells, leading to an immunosuppressant state. Recent evidence strongly suggests that the molecular mechanisms behind the modulation of inflammation by smoking mainly involve the nuclear factor-kappa B (NF-kB) family, through the activation of both an inhibitor of IkB kinase (IKK)-dependent and -independent pathway. In addition to NF-kB activation, a number of transcriptional factors including GATA, PAX5 and Smad 3/4, have also been implicated.

CONCLUSION

Multiple mechanisms may be responsible for the association of smoking and inflammation, and the identification of potential therapeutic targets should guide future research.

High-affinity immunoglobulin E receptor expression is increased in large and small airways in fatal asthma

BACKGROUND

IgE and its high-affinity receptor FcɛRI play an important role in allergy and asthma. The distribution of FcɛRI expression in the airways and within the airway wall, however, is largely unknown.

OBJECTIVE

In this study, we aimed to map the distribution of FcɛRI in different layers of large airways (LA) and small airways (SA) in lung tissue from non-smoking and smoking patients who died of asthma [fatal asthma (FA)] and non-smoking controls (CTR).

METHODS

Postmortem lung tissue from 24 cases of non-smoking FA, 13 smoking FA patients and from 19 subjects who died of non-pulmonary causes (CTR) was immunohistochemically stained for FcɛRI and AA1 (mast cell tryptase marker). The expression of these markers was analysed in inner, muscle, and outer layers of both LA and SA by image analysis.

RESULTS

FcɛRI expression was higher in non-smoking and smoking FA compared with CTR in the inner and outer layer of SA. In the outer layer of LA, FcɛRI expression was higher in non-smoking FA compared with CTR. AA1 was higher in non-smoking FA compared with smoking FA and CTR in the outer layer of the SA, which was correlated with FcɛRI in this layer.

CONCLUSION

Our results show that the expression of FcɛRI is higher in both LA and SA in FA compared with CTR. These differences are predominantly found in the outer layer where they can be attributed in part to the increased mast cell numbers. These results indicate an increased capacity to mount IgE-mediated reactions in FA, both in LA and SA.

Challenges of treating asthma in people who smoke

Cigarette smoking is common in asthma and is associated with poor symptom control and a reduced therapeutic response to inhaled and oral corticosteroids as compared with nonsmokers with asthma. This review examines the range of adverse health effects of smoking in asthma, the inflammatory mechanisms that may influence the efficacy of current drugs and discusses potential future therapeutic directions.