Impact of tobacco smoke on interleukin-16 protein in human airways, lymphoid tissue and T lymphocytes

LincRNA-Cox2 Regulates Smoke-induced Inflammation in Murine Macrophages

Cigarette smoke (CS) exposure is a risk factor for many chronic diseases, including chronic obstructive pulmonary disease, but the mechanism by which smoke exposure can alter homeostasis and bring about chronic inflammation is poorly understood. Here, we showcase a novel role for smoke in regulating long noncoding RNAs, showing that it activates lincRNA-Cox2, which we previously characterized as functional in inflammatory regulation. Exposing lincRNA-Cox2 murine models to smoke in vivo confirmed lincRNA-Cox2 as a regulator of inflammatory gene expression in response to smoke both systemically and within the lung. We also report that lincRNA-Cox2 negatively regulates genes in smoked bone marrow-derived macrophages exposed to LPS stimulation. In addition to the effects on long noncoding RNAs, we also report dysregulated transcription and splicing of inflammatory protein-coding genes in the bone marrow niche after CS exposure in vivo. Collectively, this work provides insights into how innate immune signaling from gene expression to splicing is altered after in vivo exposure to CS and highlights an important new role for lincRNA-Cox2 in regulating immune genes after smoke exposure.

Chronic Obstructive Pulmonary Disease in Women: A Biologically Focused Review with a Systematic Search Strategy

Purpose

Evidence suggests that chronic obstructive pulmonary disease (COPD) symptoms and progression may differ between men and women. However, limited information is currently available on the pathophysiological and biological factors that may underlie these sex-related differences. The objective of this review is to systematically evaluate reports of potential sex-related differences, including genetic, pathophysiological, structural, and other biological factors, that may influence COPD development, manifestation, and progression in women.

Patients and Methods

A PubMed literature search was conducted from inception until January 2020. Original reports of genetic, hormonal, and physiological differences, and biological influences that could contribute to COPD development, manifestation, and progression in women were included.

Results

Overall, 491 articles were screened; 29 articles met the inclusion criteria. Results from this analysis demonstrated between-sex differences in inflammatory, immune, genetic, structural, and physiological factors in patients with COPD.

Conclusion

Various biological differences are observed between men and women with COPD including differences in inflammatory and metabolic pathways related to obesity and fat distribution, immune cell function and autophagy, extent and distribution of emphysema and airway wall remodeling. An enhanced understanding of these differences has the potential to broaden our understanding of how COPD develops and progresses, thereby providing an opportunity to ultimately improve diagnosis, treatment, and monitoring of COPD in both men and women.

Cardiovascular Disease-Related Serum Proteins in Workers Occupationally Exposed to Polycyclic Aromatic Hydrocarbons

Chimney sweeps have higher incidence and mortality of cardiovascular disease (CVD), likely related to their exposure to polycyclic aromatic hydrocarbons (PAH). In order to identify underlying mechanisms of PAH-related CVD, we here investigated whether PAH exposure was associated with levels of putative CVD-related proteins in serum among currently working chimney sweeps. We enrolled 116 chimney sweeps and 125 unexposed controls, all nonsmoking male workers from Sweden. We measured monohydroxylated PAH metabolites in urine by liquid chromatography coupled to tandem mass spectrometry and a panel of 85 proteins in serum using proximity extension assay. Linear regression analysis adjusted for age and body mass index showed that 25 proteins were differentially expressed between chimney sweeps and the controls (p < .05, adjusted for false discovery rate). Of the 25 proteins, follistatin (FS), prointerleukin-16 (IL-16), and heat shock protein beta-1 (HSP 27) showed positive associations with the monohydroxylated metabolites of PAH in a dose-response manner (p < .05). Pathway and gene ontology analyses demonstrated that the differentially expressed proteins were mainly involved in inflammatory response and immunological functions, such as leukocyte migration, cell movement of leukocytes, and adhesion of immune cells. In conclusion, we found a number of putative CVD-related proteins differentially expressed, between PAH-exposed and unexposed individuals, and mainly involved in inflammation and immune function. Our data warrant protective measures to reduce PAH exposure and longitudinal investigations of the protein profile in chimney sweeps and other occupational groups exposed to PAH.

Long-term consumption of fruits and vegetables and risk of chronic obstructive pulmonary disease: a prospective cohort study of women

Background

Fruits and vegetables, due to high antioxidant capacity, may protect the lung from oxidative damage caused by tobacco smoke and potentially prevent chronic obstructive pulmonary disease (COPD). Only one study based on baseline diet has examined fruit and vegetable consumption in relation to risk of COPD, and no previous studies have examined long-term diet.

Methods

We investigated whether long-term fruit and vegetable consumption was associated with COPD incidence among 34 739 women (age 48-83 years) in the population-based prospective Swedish Mammography Cohort. Fruit and vegetable consumption was assessed twice (1987, 1997) with a self-administered questionnaire. Cases of COPD were identified by linkage to the Swedish health register. Cox proportional hazard regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

During follow-up from 2002 to 2014, 1512 women were diagnosed with COPD. Long-term fruit was associated with lower risk of COPD; women in the highest vs lowest quintile of consumption (≥2.5 vs <0.8 servings/day) had a 37% lower risk of COPD (95% CI: 25-48%; P-trend < 0.0001). No association was observed with long-term vegetable intake. Current and ex-smokers with low long-term consumption of fruits (<1 serving/day) in comparison to never smokers with high consumption (≥3 servings/day) had a 38-fold (HR: 38.1; 95% CI: 20.2-71.7) and 13-fold (HR: 12.5, 95% CI: 6.5-24.1) higher risk of COPD, respectively. However, no significant interaction between smoking status and fruit intake in relation to COPD incidence was observed (P-interaction = 0.95).

Conclusions

In this prospective cohort of middle-age and older women, long-term consumption of fruits but not vegetables was inversely associated with COPD incidence.

Activating transcription factor 3 represses cigarette smoke-induced IL6 and IL8 expression via suppressing NF-κB activation

Airway and lung inflammation is a fundamental hallmark of chronic obstructive pulmonary disease (COPD). Activating transcription factor 3 (ATF3) has been reported to negatively regulate many pro-inflammatory cytokines and chemokines. However, little is known about the impact of ATF3 on the inflammatory response of COPD. Since cigarette smoke (CS) is considered to be the most important risk factor in the etiology of COPD, we attempted to investigate the effects and molecular mechanisms of ATF3 in CS-induced inflammation. We observed an increase in the expression of ATF3 in the lung tissues of CS-exposed mice and CS extract (CSE)-treated human bronchial epithelial (HBE) cells. In vitro results indicated that ATF3 inhibition significantly increased the expression of proinflammatory cytokines interleukin 6 (IL6) and interleukin 8 (IL8) in CSE-stimulated HBE cells. Furthermore, in vivo data verified that CS induced inflammatory cell recruitment around the bronchus. In addition, neutrophil infiltration in bronchoalveolar lavage fluid (BALF) of CS-exposed Atf3^-/- mice was markedly higher than in stimulated WT mice. Finally, ATF3 deficiency increased the in vitro and in vivo expression and phosphorylation of nuclear factor-κB (NF-κB), a positive mediator of inflammation. Thus, this study shows that ATF3 plays an important role in the negative regulation of CS-induced pro-inflammatory gene expression through downregulating NF-κB phosphorylation.

Interleukin-16-producing NK cells and T-cells in the blood of tobacco smokers with and without COPD

Background

Long-term exposure to tobacco smoke causes local inflammation in the airways that involves not only innate immune cells, including NK cells, but also adaptive immune cells such as cytotoxic (CD8⁺) and helper (CD4⁺) T-cells. We have previously demonstrated that long-term tobacco smoking increases extracellular concentration of the CD4⁺-recruiting cytokine interleukin (IL)-16 locally in the airways. Here, we hypothesized that tobacco smoking alters IL-16 biology at the systemic level and that this effect involves oxygen free radicals (OFR).

Methods

We quantified extracellular IL-16 protein (ELISA) and intracellular IL-16 in NK cells, T-cells, B-cells, and monocytes (flow cytometry) in blood samples from long-term tobacco smokers with and without chronic obstructive pulmonary disease (COPD) and in never-smokers. NK cells from healthy blood donors were stimulated with water-soluble tobacco smoke components (cigarette smoke extract) with or without an OFR scavenger (glutathione) in vitro and followed by quantification of IL-16 protein.

Results

The extracellular concentrations of IL-16 protein in blood did not display any substantial differences between groups. Notably, intracellular IL-16 protein was detected in all types of blood leukocytes. All long-term smokers displayed a decrease in this IL-16 among NK cells, irrespective of COPD status. Further, both NK and CD4⁺ T-cell concentrations displayed a negative correlation with pack-years. Moreover, cigarette smoke extract caused release of IL-16 protein from NK cells in vitro, and this was not affected by glutathione, in contrast to the decrease in intracellular IL-16, which was prevented by this drug.

Conclusion

Long-term exposure to tobacco smoke does not markedly alter extracellular concentrations of IL-16 protein in blood. However, it does decrease the intracellular IL-16 concentrations in blood NK cells, the latter effect involving OFR. Thus, long-term tobacco smoking exerts an impact at the systemic level that involves NK cells; innate immune cells that are critical for host defense against viruses and tumors – conditions that are overrepresented among smokers.

24 year outcomes of hepatitis B vaccination in Hangzhou, China

To evaluate the impact of the universal infant HepB vaccination program on hepatitis B virus infection in Hangzhou, China. Hepatitis B incidences and HepB vaccination rates of Hangzhou from 1990 to 2003 were acquired from the historical paper-documents, while which were derived from China Information System for Diseases Control and Prevention and Zhejiang Information System for Immunization Program respectively from 2004 to 2013. A serology survey among person aged 0-59 y was conducted in Hangzhou in 2006. Participants were selected by stratified, multi-stage random sampling. Serum specimens were tested for HBsAg, anti-HBs , anti-HBc , HBeAg and anti-HBe by ELISA. For the past 24 years, hepatitis B incidence and mortality of Hangzhou declined dramatically (χ(2) = 3.2 × 10(4); χ(2) = 172.443; both P for trend < 0.001). Both urban and rural incidence descended (χ(2)urban = 1.904 × 10(4); χ(2)rural = 1.633 × 10(4) ; both P for trend < 0.001).Hepatitis B patients mainly concentrated in 20-40 y old; workers and farmers were the main infection occupations, which was varies in different years (χ(2) = 1.619 × 10(3), P < 0.001). Significant association was found between incidence of hepatitis B and HepB vaccination rate (r = 0 .946, χ(2) = 11.813, Pfor trend = 0.001). A total of 5605 participants aged 0-59 y included in this serological survey. The prevalence of HBsAg, anti-HBs, anti-HBc, HBeAg and anti-HBe were 6.19%, 45.83%, 57.25%, 0.62%, and 4.37%, respectively. Hangzhou has successfully integrated the HepB into routine immunization programs and this has had a significant impact on decreasing the incidence of hepatitis B infection.

p38 Mitogen-activated protein kinase accelerates emphysema in mouse model of chronic obstructive pulmonary disease

CONTEXT

There are few short-term mouse models of chronic obstructive pulmonary disease (COPD) mimicking the human disease. In addition, p38 is recently recognized as a target for the treatment of COPD. However, the precise mechanism how p38 contributes to the pathogenesis of COPD is still unknown.

OBJECTIVE

We attempted to create a new mouse model for COPD by intra-tracheal administration of a mixture of lipopolysaccharide (LPS) and cigarette smoke solution (CSS), and investigated the importance of the p38 mitogen-activated protein kinase (p38) pathway in the pathogenesis of COPD.

METHODS

Mice were administered LPS + CSS once a day on days 0-4 and 7-11. Thereafter, CSS alone was administered to mice once a day on days 14-18. On day 28, histopathological changes of the lung were evaluated, and bronchoalveolar lavage fluid (BALF) was subjected to western blot array for cytokines. Transgenic (TG) mice expressing a constitutive-active form of MKK6, a p38-specific activator in the lung, were subjected to our experimental protocol of COPD model.

RESULTS

LPS + CSS administration induced enlargement of alveolar air spaces and destruction of lung parenchyma. BALF analyses of the LPS + CSS group revealed an increase in expression levels of several cytokines involved in the pathogenesis of human COPD. These results suggest that our experimental protocol can induce COPD in mice. Likewise, histopathological findings of the lung and induction of cytokines in BALF from MKK6 c.a.-TG mice were more marked than those in WT mice.

CONCLUSION

In a new experimental COPD mouse model, p38 accelerates the development of emphysema.

Nicotine impairs cyclooxygenase-2-dependent kinin-receptor-mediated murine airway relaxations

INTRODUCTION

Cigarette smoke induces local inflammation and airway hyperreactivity. In asthmatics, it worsens the symptoms and increases the risk for exacerbation. The present study investigates the effects of nicotine on airway relaxations in isolated murine tracheal segments.

METHODS

Segments were cultured for 24h in the presence of vehicle, nicotine (10 μM) and/or dexamethasone (1 μM). Airway relaxations were assessed in myographs after pre-contraction with carbachol (1 μM). Kinin receptors, cyclooxygenase (COX) and inflammatory mediator expressions were assessed by real-time PCR and confocal-microscopy-based immunohistochemistry.

RESULTS

The organ culture procedure markedly increased bradykinin- (selective B₂ receptor agonist) and des-Arg⁹-bradykinin- (selective B₁ receptor agonist) induced relaxations, and slightly increased relaxation induced by isoprenaline, but not that induced by PGE₂. The kinin receptor mediated relaxations were epithelium-, COX-2- and EP2-receptor-dependent and accompanied by drastically enhanced mRNA levels of kinin receptors, as well as inflammatory mediators MCP-1 and iNOS. Increase in COX-2 and mPGES-1 was verified both at mRNA and protein levels. Nicotine selectively suppressed the organ-culture-enhanced relaxations induced by des-Arg⁹-bradykinin and bradykinin, at the same time reducing mPGES-1 mRNA and protein expressions. α7-nicotinic acetylcholine receptor inhibitors α-bungarotoxin and MG624 both blocked the nicotine effects on kinin B₂ receptors, but not those on B₁. Dexamethasone completely abolished kinin-induced relaxations.

CONCLUSION

It is tempting to conclude that a local inflammatory process per se could have a bronchoprotective component by increasing COX-2 mediated airway relaxations and that nicotine could impede this safety mechanism. Dexamethasone further reduced airway inflammation together with relaxations. This might contribute to the steroid resistance seen in some patients with asthma.

Integrative omics approach identifies interleukin-16 as a biomarker of emphysema

Interleukin-16 (IL-16) is a multifunctional cytokine that has been associated with autoimmune and allergic diseases. To investigate comprehensively whether IL-16 is also associated with chronic obstructive pulmonary disease (COPD) and emphysema, we performed an integrated analysis of multiple "omics" data. Over 500 subjects participating in the COPDGene® study donated blood and were clinically characterized and genetically profiled. IL-16 mRNA levels were measured in peripheral blood mononuclear cells (PBMC), and protein levels were measured in fresh frozen plasma. A multivariate analysis found plasma IL-16 positively associated with age and body mass index, and negatively associated with current smoking and emphysema in the upper lobes. PBMC IL-16 expression was positively associated with gender and a composite score for airflow obstruction, emphysema, and gas trapping. Whole-genome expression quantitative trait locus (eQTL) analysis identified a novel IL-16 missense SNP (rs11556218) associated with lower IL-16 in plasma. In summary, an integrated "omics" analysis in a very large cohort identified an association between decreased IL-16 and emphysema and discovered a novel IL-16 cis-eQTL. Thus IL-16 plasma levels and IL-16 genotyping may be useful in a personalized medicine approach for lung disease.

IL-16 effects on A549 lung epithelial cells: dependence on CD9 as an IL-16 receptor?

Interleukin-16 (IL-16) is a pro-inflammatory cytokine released by many types of cells found in the lungs, including normal airway and alveolar epithelial cells. Though a chemotactin for CD4(+) cells and eosinophils, IL-16 also modulates their production of factors that influence inflammatory lung diseases, e.g., asthma and allergic rhinitis. To date, little is known about any potential autocrine-like regulatory effects of IL-16. Using a model human alveolar basal epithelial A549 cell line, the present study sought to assess lung epithelial cell responses to IL-16. Potential induced effects on cell growth/function were assessed using MTT reduction, lactate dehydrogenase release, and 5-bromo-2-deoxyuridine incorporation assays. As IL-16 (at locally high levels) can induce CD4(+) cell death via apoptosis, this potential outcome among the A549 cells was also evaluated using TUNEL and changes in expression of caspase-3 and the pro-apoptotic and anti-apoptotic proteins of Bcl-2 family. The data here indicated that IL-16 inhibited A549 cell growth/function and this was associated with a marked increase in apoptosis characterized by DNA fragmentation, activation of caspase-3, and altered pro-apoptotic protein expression. Since lung epithelial cells lack the CD4 that may bind IL-16, it has been suggested that CD9 may act as an alternate receptor for this cytokine (i.e., an IL-16R). Thus, these studies also sought to determine the extent of CD9 expression on A549 cells and if any/all observed IL-16-induced changes were mediated by CD9. Flow cytometric analyses revealed the cells to be CD9(+)CD4(-). However, neutralization of the purported IL-16R with anti-CD9 antibody could not block the cytotoxic/growth inhibiting effects of IL-16. The only exception appeared to be a mitigation of a chemotactic effect of IL-16; however, studies with an equal amount of non-specific antibody (of same isotype as the anti-CD9) revealed this effect to be artefactual. The neutralization study results thus suggest to us that as-yet undefined pathway(s) exist through which IL-16 may act to exert growth inhibiting/apoptosis-inducing effects on A549 cells, a cell line routinely used as a model for lung epithelial cells.

Effects of tobacco smoke on IL-16 in CD8+ cells from human airways and blood: a key role for oxygen free radicals?

Chronic exposure to tobacco smoke leads to an increase in the frequency of infections and in the number of CD8(+) and CD4(+) cells as well as the CD4(+) chemoattractant cytokine IL-16 in the airways. Here, we investigated whether tobacco smoke depletes intracellular IL-16 protein and inhibits de novo production of IL-16 in CD8(+) cells from human airways and blood while increasing extracellular IL-16 and whether oxygen free radicals (OFR) are involved. Intracellular IL-16 protein in CD8(+) cells and mRNA in all cells was decreased in bronchoalveolar lavage (BAL) samples from chronic smokers. This was also the case in human blood CD8(+) cells exposed to water-soluble tobacco smoke components in vitro, in which oxidized proteins were markedly increased. Extracellular IL-16 protein was increased in cell-free BAL fluid from chronic smokers and in human blood CD8(+) cells exposed to water-soluble tobacco smoke components in vitro. This was not observed in occasional smokers after short-term exposure to tobacco smoke. A marker of activation (CD69) was slightly increased, whereas other markers of key cellular functions (membrane integrity, apoptosis, and proliferation) in human blood CD8(+) cells in vitro were negatively affected by water-soluble tobacco smoke components. An OFR scavenger prevented these effects, whereas a protein synthesis inhibitor, a β-adrenoceptor, a glucocorticoid receptor agonist, a phosphodiesterase, a calcineurin phosphatase, and a caspase-3 inhibitor did not. In conclusion, tobacco smoke depletes preformed intracellular IL-16 protein, inhibits its de novo synthesis, and distorts key cellular functions in human CD8(+) cells. OFR may play a key role in this context.

Lung tissue and tumour-infiltrating T lymphocytes in patients with non-small cell lung carcinoma and chronic obstructive pulmonary disease (COPD): moderate/severe versus mild stage of COPD

Cytotoxic CD8+ T cells have been suggested to be key players in the pathogenesis of chronic obstructive pulmonary disease (COPD). We wanted to investigate the phenotype of lung tissue T lymphocytes (LTL) and tumour-infiltrating T lymphocytes (TIL) in smokers with peripheral non-small cell lung carcinoma (NSCLC) with moderate/severe versus mild COPD. Lung tissue and tumour samples were obtained from patients with moderate/severe stage of COPD (n = 10) and from patients with mild stage of COPD (n = 7) at lung resection for a solitary peripheral NSCLC, processed and analysed by flow cytometry. The flow-cytometric results showed that lung tissue T cells, regardless of the severity of COPD, were mostly of the activated phenotype, expressed the CXCR3 chemokine receptor characteristic of type 1 T cells, and did neither significantly differ in the expression of activation markers (CD69, CD25 and HLA-DR), differentiation markers (CD27 and CD28) and chemokine receptors (CXCR3 and CCR4) between the selected groups, nor showed any significant correlation with lung function measured as forced expiratory volume in 1 s (FEV1) or TLCO. Compared with LTL, a significantly greater proportion of TIL expressed the activation markers CD69 and CD25, but a lower proportion showed a fully differentiated CD27- 28- phenotype. We conclude that lung LTL patterns are similar in NSCLC patients with moderate/severe or mild stages of COPD, and are not significantly related to lung function. LTL and TIL possess different phenotype characteristics. The majority of tumour tissue T cells are activated, but it seems that their process of differentiation is incomplete.

Correlates of CD4+ and CD8+ lymphocyte counts in high-risk immunodeficiency virus (HIV)-seronegative women enrolled in the women's interagency HIV study (WIHS)

Studies of human immunodeficiency virus (HIV) infection often compare values from HIV-uninfected controls, including CD4 and CD8 lymphocyte counts. Nonetheless, little is known regarding factors associated with CD4 and CD8 cell numbers in HIV-uninfected individuals. To ascertain potential factors associated with differences in CD4 and CD8 cells among HIV negative women, we studied these cells in a group of 953 women, enrolled as HIV-negative comparators in the Women's Interagency HIV Study. Using standard techniques, we measured CD4 and CD8 cells obtained during study-related visits every six months through visit 20 (maximum of 9.5 years). Results were correlated with demographic and behavioral factors, and data were analyzed using a multiple linear regression approach with generalized estimating equations. At baseline, the median age was 32.4 years, body mass index (BMI) was 26.4 kg/m(2), CD4 cell count was 1010 (range 214-2705)/microL, and CD8 cell count was 542 (range 72-2448)/microL. African-Americans comprised 54%, 24% were Hispanic, and 19% were Caucasian. In multivariate analysis, increasing age (p = 0.0006), increasing BMI (p = 0.001), and current smoking status (p = 0.03) were independent predictors of higher CD4 counts. Multivariate analyses of CD8 cells revealed that lower age (p = 0.001), higher BMI (p = 0.03), Hispanic race/ethnicity (p = 0.01); current smoking (p = 0.006), injection drug use (p = 0.02), and Hepatitis C infection (p = 0.01) were independent predictors of higher CD8 cell counts. Multiple demographic and behavioral factors may influence CD4 and CD8 counts in HIV negative women. These factors must be considered in future analyses comparing lymphocyte subsets in HIV positive and negative women.

Gene expression profiles of T lymphocytes are sensitive to the influence of heavy smoking: A pilot study

Cigarette smoke components have a proven negative influence on human health. Adverse metabolic effects were observed in tissues and single cells. T lymphocytes get in contact with affected organs (e.g., lung) or cells (e.g., erythrocytes), as well as with smoke components and bioactive molecules, whose production is triggered by tobacco smoke. We therefore compared the gene expression profiles in these cells of the adaptive immune system of three male heavy smokers and three male nonsmokers using rapid T cell isolation and Affymetrix GeneChip HG U133A 2.0 microarray analysis. Eighty-eight genes were found to be significantly (t test) differentially expressed by a factor of 1.5-fold or larger between smokers and nonsmokers. Using the gene function groups of the gene ontology consortium to categorize the functions of the differentially expressed genes, the group termed "response to stimulus" was found to be most significantly affected by smoking. Our data indicate a prominent role of cytotoxic T lymphocytes in response to smoking. Several genes that are typically expressed in these cells were found regulated although the ratio of cytotoxic and helper T lymphocytes remained unchanged in smokers. Our data show that, in principle, it might be possible to identify health-related biomarkers in the transcriptome of T lymphocytes.

Cigarette smoke extract modulates respiratory defence mechanisms through effects on T-cells and airway epithelial cells

Chronic obstructive pulmonary disease (COPD) is a disease primarily caused by cigarette smoking, which in turn has been shown to affect the susceptibility to and progression of airway infections. The question addressed in this study was how components from cigarette smoke could affect the defence mechanisms of T-cells and epithelial cells, and thereby contribute to the development of the COPD pathology. T-cells and monocytes were isolated from buffycoats from healthy donors and T-cell responses studied in response to cigarette smoke extract (CSE). Activation level (CD25 expression), proliferation (BrdU incorporation) and intracellular expression of the cytotoxic markers granzyme-b and TIA-1 were determined using flowcytometry. Normal human bronchial epithelial cells were obtained from Cambrex and differentiated in air-liquid interface cultures. After exposure to CSE barrier function (trans-epithelial electric resistance, TEER), MUC5AC and interleukin-8 production were measured. T-cell activation, proliferation and expression of the cytotoxic proteins granzyme-b and TIA-1 were significantly reduced in response to 0.5-1% of CSE. The epithelial cells were more resistant to CSE and responded at doses 20 times higher than T-cells. The expression of interleukin-8 and MUC5AC was significantly increased after exposure to 15% and 30% CSE and TEER was largely unaffected at 30% CSE but clearly reduced at 40% CSE. This study shows that mechanisms, in both T-cells and airway epithelial cells, involved in the defence against infectious agents are modulated by CSE.