Cigarette smoke extract induces cytotoxicity on human nasal epithelial cells

Mucociliary Clearance of Different Respiratory Conditions: A Clinical Study

Introduction  Mucociliary clearance (MCC) is the first line of defense of the pulmonary system. Mucociliary clearance impairment may lead to increased risk of respiratory infections, lung injury, pulmonary repair problems, chronic dysfunctions and progression of respiratory diseases. Objective  To characterize the MCC of active and passive smokers and individuals with chronic obstructive pulmonary disease (COPD) and compare the MCC behaviors between men and women of different age groups. Methods  Patients with COPD (current smokers and ex-smokers) and apparently healthy individuals (current smokers, passive smokers and nonsmokers) were evaluated. All of the subjects underwent lung function and MCC evaluation (saccharin transport test [STT]). Smokers (with or without COPD) were questioned about the smoking history. Results  A total of 418 individuals aged 16 to 82 years old, of both genders, were evaluated. The STT values of active and passive smokers were statistically higher than those of the control group ( p  < 0.01). Men of the control group had lower values of STT than active smokers (9.7 ± 7.1 and 15.4 ± 10.1 minute, respectively, p  < 0.01). In addition, higher MCC velocity was observed in women that are current smokers (11.7 ± 6.8 minute) compared with men (15.4 ± 10.1 minute) in this group ( p  = 0.01). Among the younger age groups (< 50 years old), only passive smokers presented higher STT in relation to the control group. Conclusion  Passive and active smoking are factors that influence negatively the MCC, and passive smokers may present losses of this mechanism at a younger age. Additionally, male smokers present worse MCC than male nonsmokers.

Protective Effect of Aerobic Exercise on the Nasal Mucosa of Rats Against the Histopathologic Changes in Cigarette Smoke Exposure

INTRODUCTION

Smoking is a public health problem that has been proven to have adverse effects on human health. Aerobic exercise has positive effects on the human body, especially on the respiratory system.

OBJECTIVE

The aim of this experimental animal model study was to determine whether regular aerobic exercise has a protective effect against the harmful effects of cigarette smoke on the nasal mucosa of rats.

METHODS

A total of 24 male Wistar albino rats were randomly separated into 3 groups of 8: group 1 (cigarette smoking), group 2 (cigarette smoking and exercise), and group 3 (control group). At the end of the experiment period, histopathological (light and electron microscopy) and immunohistochemical (GSTA 1, CYP1A1, and CYP2E1) evaluations were made of the nasal mucosa of the animals.

RESULTS

Goblet cell loss and basal membrane thickening were significantly lower in group 2 and group 3 compared to group 1. In the electron microscope evaluation, the inflammatory expressions of the goblet cells were observed in a very small area in group 2. In group 1, these were distributed over large areas between the mucosal cells. There was seen to be significant swelling of the mitochondria in group 1 compared to the other groups. No statistically significant difference was determined between the groups with respect to GSTA1, CYP2E1, and CYP1A1 scores (P > .05).

CONCLUSION

The results of this study showed that regular aerobic exercise has a protective effect against the harmful effects of smoking on the nasal mucosa of rats.

SIRT5 prevents cigarette smoke extract-induced apoptosis in lung epithelial cells via deacetylation of FOXO3

Cigarette smoking plays an important role in increased incidence of chronic obstructive pulmonary disease (COPD). The underlying mechanism in which cigarette smoking induced impairment of lung epithelial cells is still unknown. SIRT5 is a nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylase, which has been implicated in the regulation of metabolism, stress responses, and aging. Forkhead box O3 (FOXO3) belongs to the O subclass of the forkhead family of transcription factors. It is also involved in protection from oxidative stress by upregulating antioxidants in epithelial cells. Here, we show that cigarette smoke extract (CSE) induces SIRT5 to deacetylate FOXO3 at K271 and K290. Deacetylation of FOXO3 promotes its nuclear localization. Notably, transfection with FOXO3 K271R- or K290R-attenuated CSE-induced apoptosis in SIRT5 knocked down cells, suggesting the protective effects of SIRT5, is mediated by FOXO3. In contrast, CSE stress upregulates SIRT5, which activates FOXO3α leading to rescuing apoptosis. Thus, SIRT5 constitutes a determinant of apoptosis by CSE in lung epithelial cells.

Rapid shedding of proinflammatory microparticles by human mononuclear cells exposed to cigarette smoke is dependent on Ca2+ mobilization

OBJECTIVES

Microparticles are membrane vesicles shed by cells upon activation and apoptosis. Agonists capable of inducing microparticle generation include cytokines, bacterial products, P-selectin, histamine. Cigarette smoke extract has also been recognized as an agonist involved in microparticle generation with an apoptosis-dependent mechanism. We investigated the possibility that cigarette smoke extract induces the rapid generation of proinflammatory microparticles by human mononuclear cells with a calcium-dependent mechanism.

MATERIALS AND METHODS

Human mononuclear cells were exposed to cigarette smoke extract. [Ca(2+)]i mobilization was assessed with the fluorescent probe Fluo-4 NW. Microparticles were quantified with a prothrombinase assay and by flow cytometry. Normal human bronchial epithelial cells and A549 alveolar cells were incubated with cigarette smoke extract-induced microparticles and the generation of ICAM-1, IL-8, and MCP-1 was assessed by ELISA.

RESULTS

Exposure to cigarette smoke extract induced a rapid increase in [Ca(2+)]i mobilization. Microparticle generation was also increased. EGTA, verapamil and the calmodulin inhibitor, W-7, inhibited microparticle generation. Incubation of lung epithelial cells with cigarette smoke extract-induced microparticles increased the expression of proinflammatory mediators.

CONCLUSIONS

Exposure of mononuclear cells to cigarette smoke extract causes a rapid shedding of microparticles with a proinflammatory potential that might add to the mechanisms of disease from tobacco use.

Inflammatory and cytotoxic effects of acrolein, nicotine, acetylaldehyde and cigarette smoke extract on human nasal epithelial cells

BACKGROUND

Cigarette smoke induces a pro-inflammatory response in airway epithelial cells but it is not clear which of the various chemicals contained within cigarette smoke (CS) should be regarded as predominantly responsible for these effects. We hypothesised that acrolein, nicotine and acetylaldehyde, important chemicals contained within volatile cigarette smoke in terms of inducing inflammation and causing addiction, have immunomodulatory effects in primary nasal epithelial cell cultures (PNECs).

METHODS

PNECs from 19 healthy subjects were grown in submerged cultures and were incubated with acrolein, nicotine or acetylaldehyde prior to stimulation with Pseudomonas aeruginosa lipopolysaccharide (PA LPS). Experiments were repeated using cigarette smoke extract (CSE) for comparison. IL-8 was measured by ELISA, activation of NF-κB by ELISA and Western blotting, and caspase-3 activity by Western blotting. Apoptosis was evaluated using Annexin-V staining and the terminal transferase-mediated dUTP nick end-labeling (TUNEL) method.

RESULTS

CSE was pro-inflammatory after a 24 h exposure and 42% of cells were apoptotic or necrotic after this exposure time. Acrolein was pro-inflammatory for the PNEC cultures (30 μM exposure for 4 h inducing a 2.0 fold increase in IL-8 release) and also increased IL-8 release after stimulation with PA LPS. In contrast, nicotine had anti-inflammatory properties (0.6 fold IL-8 release after 50 μM exposure to nicotine for 24 h), and acetylaldehyde was without effect. Acrolein and nicotine had cellular stimulatory and anti-inflammatory effects respectively, as determined by NF-κB activation. Both chemicals increased levels of cleaved caspase 3 and induced cell death.

CONCLUSIONS

Acrolein is pro-inflammatory and nicotine anti-inflammatory in PNEC cultures. CSE induces cell death predominantly by apoptotic mechanisms.

Comparison of nasal and bronchial epithelial cells obtained from patients with COPD

For in vitro studies of airway pathophysiology, primary epithelial cells have many advantages over immortalised cell lines. Nasal epithelial cells are easier to obtain than bronchial epithelial cells and can be used as an alternative for in vitro studies. Our objective was to compare nasal and bronchial epithelial cells from subjects with COPD to establish if these cells respond similarly to pro-inflammatory stimuli. Cell cultures from paired nasal and bronchial brushings (21 subjects) were incubated with cigarette smoke extract (CSE) prior to stimulation with Pseudomonas aeruginosa lipopolysaccharide. IL-6 and IL-8 were measured by ELISA and Toll-like receptor 4 (TLR-4) message and expression by RT-PCR and FACS respectively. IL-8 release correlated significantly between the two cell types. IL-6 secretion was significantly less from bronchial compared to nasal epithelial cells and secreted concentrations did not correlate. A 4 h CSE incubation was immunosuppressive for both nasal and bronchial cells, however prolonged incubation for 24 h was pro-inflammatory solely for the nasal cells. CSE reduced TLR-4 expression in bronchial cells only after 24 h, and was without effect on mRNA expression. In subjects with COPD, nasal epithelial cells cannot substitute for in vitro bronchial epithelial cells in airway inflammation studies.

Whole cigarette smoke promotes human gingival epithelial cell apoptosis and inhibits cell repair processes

BACKGROUND AND OBJECTIVE

Smoking cigarettes increases the risk of developing various types of human diseases, including cancers and periodontitis. As gingival epithelial cells are known to play an active role in innate immunity via the secretion of a wide variety of mediators, and as these cells are the first ones exposed to environmental stimuli such as cigarette smoke, we sought to investigate the effects of whole cigarette smoke on normal human gingival epithelial cells and tissue.

MATERIAL AND METHODS

Human gingival epithelial cells were extracted from healthy nonsmokers and used either as a monolayer or as an engineered human oral mucosa to investigate the effect of whole cigarette smoke on cell growth, apoptosis and wound repair/migration.

RESULTS

Our findings show that when gingival epithelial cells were exposed once to whole cigarette smoke, this resulted in a significant inhibition of cell growth through an apoptotic pathway, as confirmed by an increase of Bax and a decrease of Bcl-xL and caspase-3 activity. Cigarette smoke also inhibited epithelial cell migration. These effects may explain the disorganization of the engineered human oral mucosa tissue when exposed to whole cigarette smoke.

CONCLUSION

Exposure to whole cigarette smoke markedly inhibits epithelial cell growth through an apoptosis/necrosis pathway that involves Bax and Bcl-xL proteins and caspase-3 activity. Cigarette smoke also disrupts epithelial cell migration, which may negatively affect periodontal wound healing.

Tobacco smoke mediated induction of sinonasal microbial biofilms

Cigarette smokers and those exposed to second hand smoke are more susceptible to life threatening infection than non-smokers. While much is known about the devastating effect tobacco exposure has on the human body, less is known about the effect of tobacco smoke on the commensal and commonly found pathogenic bacteria of the human respiratory tract, or human respiratory tract microbiome. Chronic rhinosinusitis (CRS) is a common medical complaint, affecting 16% of the US population with an estimated aggregated cost of $6 billion annually. Epidemiologic studies demonstrate a correlation between tobacco smoke exposure and rhinosinusitis. Although a common cause of CRS has not been defined, bacterial presence within the nasal and paranasal sinuses is assumed to be contributory. Here we demonstrate that repetitive tobacco smoke exposure induces biofilm formation in a diverse set of bacteria isolated from the sinonasal cavities of patients with CRS. Additionally, bacteria isolated from patients with tobacco smoke exposure demonstrate robust in vitro biofilm formation when challenged with tobacco smoke compared to those isolated from smoke naïve patients. Lastly, bacteria from smoke exposed patients can revert to a non-biofilm phenotype when grown in the absence of tobacco smoke. These observations support the hypothesis that tobacco exposure induces sinonasal biofilm formation, thereby contributing to the conversion of a transient and medically treatable infection to a persistent and therapeutically recalcitrant condition.

Innate immunity

Innate immunity is an exciting area of research in rhinology because emerging evidence suggests that abnormal local immune responses, rather than pathogen-specific adaptive immunity, may play a more important role in the pathogenesis of chronic rhinosinusitis (CRS). This article reviews important recent research regarding the innate immune system and CRS, with particular focus on the role of pattern recognition receptors, antimicrobial peptides and biofilms, epithelial ciliary function, cystic fibrosis, and cigarette smoking, and on areas for future research and therapy.

Involving stakeholders to optimize a study protocol on secondhand tobacco smoke and chronic rhinosinusitis in adults

BACKGROUND

Epidemiological evidence evaluating the association between secondhand smoke exposure and diseases of the upper airway in adults is limited by a small number of studies and a lack of established protocols. This study was designed to optimize a research protocol on secondhand tobacco smoke exposure and chronic rhinosinusitis for a future population-based case-control study in Washington County, Maryland, using a participatory research model.

METHODS

We conducted three focus groups with health professionals, community members, and research practitioners for protocol development; 10 one-on-one cognitive testings with community members for protocol refinement; and a pilot testing of the full study protocol (10 cases and 10 controls) for full evaluation of the study protocol.

RESULTS

Health professionals recommended, among other themes, enrolling patients with confirmed chronic rhinosinusitis (minimum 12-week symptom duration and objective inflammation). Community members and research practitioners discussed optimal strategies for participant recruitment and interviewing. The protocol, revised with the focus group's feedback, was further evaluated in one-on-one sessions with 10 Washington County residents (3 with chronic rhinosinusitis). In the pilot study, 10 nonsmoking chronic rhinosinusitis cases (5 clinic based and 5 community based) and their community-based age, sex, and former/never smoking-matched controls were recruited. Sinonasal symptoms scores were higher in cases than controls but similar for clinic versus community-based cases.

CONCLUSION

This protocol development framework involving stakeholders resulted in a comprehensive questionnaire that was successfully evaluated during a pilot study and is now ready to be used in population-based and clinical epidemiological studies of chronic rhinosinusitis in adults.

Secondhand tobacco smoke exposure and chronic rhinosinusitis: a population-based case-control study

BACKGROUND

Rhinosinusitis is a costly disease that adversely affects quality of life (QOL). It is known to be influenced by environmental factors, but few studies have evaluated the association between secondhand tobacco smoke (SHS) exposure and chronic rhinosinusitis (CRS). To address this evidence gap, we evaluated the association of SHS and CRS risk in a community-based case-control study of adult nonsmokers.

METHODS

In Washington County, MD, 100 cases with a confirmed diagnosis of CRS and 100 controls matched for age, sex, and smoking status (former-never) were recruited and interviewed. A validated questionnaire was used to assess past and present SHS exposure as well as disease-specific QOL.

RESULTS

Compared with those who reported no SHS exposure, current or childhood SHS exposure was associated with significantly increased risk of CRS (odds ratio, 2.33; 95% CI, 1.02, 5.34). CRS cases exposed to SHS (n = 39) had worse mean scores in nasal obstruction/blockage (3.1 versus 2.5; p = 0.02), nasal discharge (3.3 versus 2.7; p = 0.03), headaches (2.4 versus 1.5; p = 0.01), and cough (2.1 versus 1.5; p = 0.04) than cases without SHS exposure (n = 61). Cases exposed to SHS were also more likely to use nasal decongestants (53.9% versus 34.4%; p = 0.05).

CONCLUSION

Exposure to SHS during childhood and adulthood may be a risk factor for CRS. Furthermore, compared with unexposed CRS cases, SHS exposed cases reported worse nasal symptoms and used more nasal decongestants compared with unexposed cases, suggesting SHS exposure is related to exacerbation and more severe symptoms.

Chronic cigarette smoke extract treatment selects for apoptotic dysfunction and mitochondrial mutations in minimally transformed oral keratinocytes

Cigarette smoke demonstrates a carcinogenic effect through chronic exposure, not acute exposures. However, current cell line models study only the acute effects of cigarette smoke. Using a cell line model, we compared the effects of acute versus chronic cigarette smoke extract (CSE) on mitochondria in minimally transformed oral keratinocytes (OKF6). OKF6 cells were treated with varying concentrations of CSE for 6 months. Cells were analyzed monthly by flow cytometry for mitochondrial membrane potential (MMP), cytochrome c release, caspase 3 activation and viability after CSE exposure. At each time point, the same assays were performed after 24 hr of valinomycin (MMP-depolarizing agent) treatment. The mitochondrial DNA of chronically CSE-treated cells was sequenced. After 6 months of CSE treatment, the cells were increasingly resistant to CSE-mediated and valinomycin-induced cell death. In addition, chronic CSE treatment caused chronic depolarization of MMP, cytochrome c release and caspase activation. Cells grown in the presence of only CSE vapor also exhibited the same resistance and chronic baseline apoptotic activation. Mitochondrial DNA sequencing found that chronic CSE-treated cells had more amino acid-changing mitochondrial mutations than acutely treated cells. CSE treatment of normal cells select for apoptotic dysfunction as well as mitochondrial mutations. These findings suggest that chronic tobacco exposure induces carcinogenesis via selection of apoptosis resistance and mitochondrial mutation in addition to previously known genotoxic effects that were found by acute treatments. Chronic models of tobacco exposure on upper aerodigestive epithelia may be more insightful than models of acute exposure in studying head and neck carcinogenesis.

Effects of cigarette smoking on the respiratory epithelium and its role in the pathogenesis of chronic rhinosinusitis

The increasing consumption of cigarettes has aroused concerns about the development and worsening of diseases, particularly those related to the respiratory tract.

Aim

In this paper we review the evidence suggesting the effects of cigarette smoking on the respiratory epithelium and its role in the pathogenesis in chronic rhinosinusitis.

Conclusions

Although there is evidence supporting a link between smoking and CRS, studies suggest that there might be individual susceptibility to cigarette smoking causing the development and/or maintenance of CRS. Proper patient educations to quit smoking as well as reinforcement of antismoking campaigns are extremely important to control this disease of major socio-economic impact.

Cigarette smoke extract enhances rhinovirus-induced toll-like receptor 3 expression and interleukin-8 secretion in A549 cells

BACKGROUND

Using A549 alveolar epithelial type II-like cells, we investigated the effects of cigarette smoke on the expression of rhinovirus (RV)-induced Toll-like receptor (TLR) 3, interleukin (IL)-6, and IL-8 secretion and viral replication.

METHODS

Cigarette smoke extract (CSE) was prepared by smoking two commercial cigarettes with filters (0.9-mg of nicotine and 8.5-mg of tar per cigarette). Cells were infected with RV serotype 16 (RV-16) and cultured for 2 days (RV group), pretreated with 1, 2.5, or 5% CSE for 1 day before RV infection, and culture with CSE for 2 days after infection (RV plus CSE group), or were cultured in medium for 3 days (control group), treated with 1, 2.5, or 5% CSE for 3 days (CSE group). Changes in TLR3, IL-6, and IL-8 mRNA expression were assayed by real-time polymerase chain reaction and TLR3 protein expression were assessed by flow cytometry; IL-6 and IL-8 secretions were measured by ELISA; and RV replication was assessed by viral culture.

RESULTS

CSE increased RV-induced TLR3 expression and RV-induced IL-8 secretion at lower concentrations in A549 cells. On the contrary, CSE dose dependently inhibited RV-induced IL-6 secretions and had no effect on RV replications.

CONCLUSION

Our results suggest that cigarette smoke may potentiate viral common cold symptoms by enhancing IL-8 secretion at lower concentrations, but not by increasing viral replication.

Bronchial airway epithelial cell damage following exposure to cigarette smoke includes disassembly of tight junction components mediated by the extracellular signal-regulated kinase 1/2 pathway

BACKGROUND

Through a variety of biochemical mechanisms, cigarette smoke (CS) may damage airway epithelium, altering its normal structure and function. Injury to epithelium may include changes in tight junction (TJ) integrity with impairment of epithelial barrier function.

METHODS AND RESULTS

To study the effect of the exposure to CS condensate (CSC) on TJ integrity, two human bronchial epithelial cell lines (HBECs), BEAS-2B and 16HBE14o-, were used. Exposure of the two HBECs to CSC resulted in a time-dependent and concentration-dependent disassembly of TJs, which were already detectable at 24 h at all the CSC concentrations tested (5%, 10%, and 20%), associated with changes in cell shape, suggesting cell damage. However, a significant inhibition of cell growth and an increase in DNA fragmentation were detected only at the highest CSC concentration tested (20%) at 48 and 72 h, respectively. The involvement of epidermal growth factor receptor (EGFR)-extracellular signal-regulated kinase (ERK) 1/2 cascade in CSC-induced damage was shown by the observation that exposure to CSC (5%) induced a marked phosphorylation of ERK1/2, already detectable after 5-min incubation and confirmed by the demonstration that not only ERK1/2 phosphorylation but also CSC-induced TJ disassembly and DNA fragmentation were partially inhibited by a mitogen-activated protein kinase kinase inhibitor (U0126) and completely blocked by a EGFR inhibitor (AG1478).

CONCLUSION

CSC-induced damage to airway epithelium includes disassembly of TJs, modulated through the EGFR-ERK1/2 signaling pathway.

Cigarette Smoke Exposure Impairs Respiratory Epithelial Ciliogenesis

Background

Cigarette smoke exposure is considered an important negative prognostic factor for chronic rhinosinusitis (CRS) patients. However, there is no clear mechanistic evidence implicating cigarette smoke exposure in the poor clinical evolution of the disease or in the maintenance of the inflammatory state characterizing CRS. This study aimed to evaluate the effects of cigarette smoke exposure on respiratory cilia differentiation.

Methods

Mouse nasal septal epithelium cultures grown at an air-liquid interface were used as a model of respiratory epithelium. After 5 days of cell growth, cultures were exposed to air on the apical surface. Additionally, cigarette smoke condensate (CSC; the particulate phase of tobacco smoke) or cigarette smoke extract (CSE; the volatile phase) were diluted in the basolateral compartment in different concentrations. After 15 days of continuous exposure, scanning electron microscopy and immunofluorescence for type IV tubulin were used to determine presence and maturation of cilia. Transepithelial resistance was also recorded to evaluate confluence and physiological barrier integrity.

Results

CSC and CSE impair ciliogenesis in a dose-dependent manner with notable effects in concentrations higher than 30 μg/mL, yielding >70% nonciliation and shorter cilia compared with control. No statistical difference on transepithelial resistance was evident.

Conclusion

CSC and CSE exposure negatively impacts ciliogenesis of respiratory cells at concentrations not effecting transepithelial resistance. The impairment on ciliogenesis reduces the mucociliary clearance apparatus after injury and/or infection and may explain the poor response to therapy for CRS patients exposed to tobacco smoke.

The cigarette smoke component acrolein inhibits expression of the innate immune components IL-8 and human beta-defensin 2 by sinonasal epithelial cells

BACKGROUND

Tobacco use is associated with poorer outcomes of medical and surgical therapy for chronic rhinosinusitis (CRS), although the underlying mechanism is unknown. Acrolein (AC) is a major component of cigarette smoke that has been shown to suppress innate immune gene expression by human bronchial epithelial cells and murine macrophages. In this study, we explore whether exposure of human sinonasal epithelial cells (HSNECs) to AC similarly reduces their innate immune gene expression.

METHODS

Primary HSNECs from CRS patients were grown in culture, either differentiated or submerged. HSNECs were treated for 30 minutes with 0-50 microM of AC and were subsequently analyzed by real-time polymerase chain reaction and ELISA to determine IL-8 and human beta-defensin (HBD) 2 expression. Total glutathione was measured to see the oxidative stress within the treatment range.

RESULTS

In primary HSNEC, IL-8 mRNA levels decreased dose dependently in the range of 10-50 microM of AC with an eightfold decrease at 50 microM. In addition, a 125-fold decrease at 50 microM for IL-8 protein was observed. HBD-2 mRNA decreased twofold and HBD-2 protein decreased fourfold at 50 microM of AC in primary HSNEC. However, differentiated HSNEC showed a marginal decrease in a dose-dependent manner for both IL-8 and HBD-2 within the range of 10-50 microM of AC. There was no oxidative stress observed over this range of AC concentration.

CONCLUSION

The tobacco smoke component AC has the capacity to suppress the inflammatory and innate immune function of sinonasal epithelial cells. Whether this effect contributes to the negative clinical impact of smoking on CRS outcomes merits additional investigation.