Interaction of cigarette exposure and airway epithelial cell gene expression

Relationship between triglyceride-glucose index and endometriosis: a cross-sectional analysis

BACKGROUND

The link between insulin resistance and endometriosis is not well established. The triglyceride-glucose (TyG) index serves as a straightforward and economical indicator of insulin resistance. This study examines the link between the TyG index and the prevalence of endometriosis in a U.S.

COHORT

METHODS

This cross-sectional study analyzed data from the NHANES conducted between 1999 and 2006. Reproductive health was assessed through questionnaires, and the TyG index was derived from fasting triglyceride and glucose measurements. Weighted logistic regression models were used to analyze the relationship between the TyG index and endometriosis. Restricted cubic spline (RCS) curves explored the linear relationship, while stratified and sensitivity analyses assessed potential interactions and the robustness of the findings.

RESULTS

The study included 2,346 women, with 176 diagnosed with endometriosis and 2,170 without. Women with endometriosis exhibited an elevated TyG index compared to those without the condition. The weighted logistic regression analysis revealed that the TyG index is an independent risk factor for endometriosis (OR = 1.58, 95% CI 1.17-2.14, p = 0.004). RCS analysis indicated a significant positive linear association between the TyG index and endometriosis, with a turning point at 8.51. Subgroup analysis indicated a stronger association in certain populations. The post-propensity score matching analysis confirmed the robustness of these findings.

CONCLUSION

In the U.S. population, a higher TyG index is positively and linearly associated with endometriosis prevalence. Effective management of blood glucose and lipid levels may reduce the prevalence of endometriosis.

Secretome profiling of human epithelial cells exposed to cigarette smoke extract and their effect on human lung microvascular endothelial cells

Cigarette smoke (CS) is one of the leading causes of pulmonary diseases and can induce lung secretome alteration. CS exposure-induced damages to human pulmonary epithelial cells and microvascular endothelial cells have been extensively demonstrated; however, the effects of the secretome of lung epithelial cells exposed to CS extracts (CSE) on lung microvascular endothelial cells are not fully understood. In this study, we aimed to determine the effects of the secretome of lung epithelial cells exposed to CSE on lung microvascular endothelial cells. Human lung epithelial cells, A549, were exposed to CSE, and the secretome was collected. Human lung microvascular endothelial cells, HULEC-5a, were used to evaluate the effect of the secretome of A549 exposed to CSE. Secretome profile, endothelial cell death, inflammation, and permeability markers were determined. CSE altered the secretome expression of A549 cells, and secretome derived from CSE-exposed A549 cells caused respiratory endothelial cell death, inflammation, and moderately enhanced endothelial permeability. This study demonstrates the potential role of cellular interaction between endothelial and epithelial cells during exposure to CSE and provides novel therapeutic targets or beneficial biomarkers using secretome analysis for CSE-related respiratory diseases.

Whole transcriptome analyis of human lung tissue to identify COPD-associated genes

Identification of the dysfunctional genes in human lung from patients with Chronic obstructive pulmonary disease (COPD) will help understand the pathology of this disease. Here, using transcriptomic data of lung tissue for 91 COPD cases and 182 matched healthy controls from the Genotype-Tissue Expression (GTEx) database. we identified 1359 significant differentially expressed genes (DEG) with 707 upregulated and 602 downregulated respectively. We evaluated the identified DEGs in an independent microarray cohort of 219 COPD and 108 controls, demonstrating the robustness of our result. Functional annotation of COPD-associated genes highlighted the activation of complement cascade, dysregulation of inflammatory response and extracellular matrix organization in the COPD patients. In addition, we identified several novel key-hub genes involved in the COPD pathogenesis using a network analysis method. To our knowledge, our analysis is currently the largest RNA-seq based COPD transcriptomic analyses, providing great resource for the molecular research in the COPD community.

Tumor secreted ANGPTL2 facilitates recruitment of neutrophils to the lung to promote lung pre-metastatic niche formation and targeting ANGPTL2 signaling affects metastatic disease

The pre-metastatic niche (PMN) represents an abnormal microenvironment devoid of cancer cells, but favoring tumor growth. Little is known about the mechanisms that generate the PMN or their effects on host cells within metastasis-prone organs. Here, we investigated by using spontaneous metastatic models whether lung epithelial cells are essential for primary tumor induced neutrophil recruitment in lung and subsequently initiating PMN formation in osteosarcoma. We found that serum levels of ANGPTL2 in osteosarcoma patients are significantly higher compared to those in healthy controls and that ANGPTL2 secretion by tumor cells plays an essential role in osteosarcoma metastasis. We determined that tumor-derived ANGPTL2 stimulates lung epithelial cells, which is essential for primary tumor-induced neutrophil recruitment in lung and subsequent pre-metastatic niche formation. Lastly, we identified that a p63 isoform, ΔNp63, drives high level of ANGPTL2 secretion and pharmaceutical inhibition of ANGPTL2 signaling by a non–RGD-based integrin binding peptide (ATN-161) diminished metastatic load in lungs likely due to reduction of the lung pre-metastatic niche formation.

The Protective Effect of HBO1 on Cigarette Smoke Extract-Induced Apoptosis in Airway Epithelial Cells

Purpose

Epigenetic modification is one of most important mechanisms underlying the pathogenesis of chronic obstructive pulmonary disease (COPD). The purpose of this study was to determine whether histone acetyltransferase binding to ORC1 (HBO1) can protect against cigarette smoke (CS)-induced cell apoptosis and sustain normal histone acetylation in COPD.

Methods

Human lung tissue samples were obtained from patients who underwent lung resection. The emphysema mouse model and HBO1 overexpressing mice were each established by intraperitoneal injection with cigarette smoke extract (CSE) or intratracheal lentiviral vectors instillation. TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assays were used to assess apoptotic ratio in mice. The apoptosis of human bronchial epithelial cells (HBECs) was assayed by flow cytometry. HBO1, B-cell lymphoma-2 (BCL-2), and H3K14ac protein expression were detected by Western blotting. HBO1 mRNA expression was measured by quantitative real-time polymerase chain reaction.

Results

Protein expression of HBO1 was decreased significantly in lung tissue from COPD patients and CSE-treated emphysema mouse models. Overexpression of HBO1 attenuated CSE-induced emphysematous changes, as well as apoptosis in the lungs of COPD mice. In vitro, the HBO1 protein degraded in a time- and dose-dependent course with CSE treatment. With flow cytometry, we proved that HBO1 could reverse the apoptosis of HBECs induced by CSE. Furthermore, HBO1 overexpression promoted the expression of anti-apoptotic BCL-2 protein and enhanced H3K14 acetylation in airway epithelial cells.

Conclusion

These findings demonstrate that the key histone modulator HBO1 plays a protective role in COPD pathogenesis that may shed light on potential therapeutic targets to inhibit the progress of COPD.

A Device for measuring the in-situ response of Human Bronchial Epithelial Cells to airborne environmental agents

Measuring the time evolution of response of Normal Human Bronchial Epithelial (NHBE) cells to aerosols is essential for understanding the pathogenesis of airway disease. This study introduces a novel Real-Time Examination of Cell Exposure (RTECE) system, which enables direct in situ assessment of functional responses of the cell culture during and following exposure to environmental agents. Included are cell morphology, migration, and specialised responses, such as ciliary beat frequency (CBF). Utilising annular nozzles for aerosol injection and installing windows above and below the culture, the cells can be illuminated and examined during exposure. The performance of RTECE is compared to that of the commercial Vitrocell by exposing NHBE cells to cigarette smoke. Both systems show the same mass deposition and similar trends in smoke-induced changes to monolayer permeability, CBF and transepithelial resistance. In situ measurements performed during and after two exposures to smoke show that the CBF decreases gradually during both exposures, recovering after the first, but decreasing sharply after the second. Using Particle image velocimetry, the cell motions are monitored for twelve hours. Exposure to smoke increases the spatially-averaged cell velocity by an order of magnitude. The relative motion between cells peaks shortly after each exposure, but remains elevated and even increases further several hours later.

Deregulation of Biologically Significant Genes and Associated Molecular Pathways in the Oral Epithelium of Electronic Cigarette Users

We have investigated the regulation of genes and associated molecular pathways, genome-wide, in oral cells of electronic cigarette (e-cigs) users and cigarette smokers as compared to non-smokers. Interrogation of the oral transcriptome by RNA-sequencing (RNA-seq) analysis showed significant number of aberrantly expressed transcripts in both e-cig users (vapers) and smokers relative to non-smokers; however, smokers had ~50% more differentially expressed transcripts than vapers (1726 versus 1152). Whereas the deregulated transcripts in smokers were predominately from protein-coding genes (79% versus 53% in vapers), nearly 28% of the aberrantly expressed transcripts in vapers (versus 8% in smokers) belonged to regulatory non-coding RNAs, including long intergenic non-coding, antisense, small nucleolar and misc RNA (P < 0.0001). Molecular pathway and functional network analyses revealed that "cancer" was the top disease associated with the deregulated genes in both e-cig users and smokers (~62% versus 79%). Examination of the canonical pathways and networks modulated in either e-cig users or smokers identified the "Wnt/Ca⁺ pathway" in vapers and the "integrin signaling pathway" in smokers as the most affected pathways. Amongst the overlapping functional pathways impacted in both e-cig users and smokers, the "Rho family GTPases signaling pathway" was the top disrupted pathway, although the number of affected targets was three times higher in smokers than vapers. In conclusion, we observed deregulation of critically important genes and associated molecular pathways in the oral epithelium of vapers that bears both resemblances and differences with that of smokers. Our findings have significant implications for public health and tobacco regulatory science.

Temporal differentiation of bovine airway epithelial cells grown at an air-liquid interface

There is an urgent need to develop improved, physiologically-relevant in vitro models of airway epithelia with which to better understand the pathological processes associated with infection, allergies and toxicological insults of the respiratory tract of both humans and domesticated animals. In the present study, we have characterised the proliferation and differentiation of primary bovine bronchial epithelial cells (BBECs) grown at an air-liquid interface (ALI) at three-day intervals over a period of 42 days from the introduction of the ALI. The differentiated BBEC model was highly representative of the ex vivo epithelium from which the epithelial cells were derived; a columnar, pseudostratified epithelium that was highly reflective of native airway epithelium was formed which comprised ciliated, goblet and basal cells. The hallmark defences of the respiratory tract, namely barrier function and mucociliary clearance, were present, thus demonstrating that the model is an excellent mimic of bovine respiratory epithelium. The epithelium was fully differentiated by day 21 post-ALI and, crucially, remained healthy and stable for a further 21 days. Thus, the differentiated BBEC model has a three-week window which will allow wide-ranging and long-term experiments to be performed in the fields of infection, toxicology or general airway physiology.

MicroRNA expression profiling defines the impact of electronic cigarettes on human airway epithelial cells

While all forms of tobacco exposure have negative health effects, the significance of exposure to electronic cigarettes (eCig) is not fully understood. Here, we studied the global effects of eCig on the micro RNA (miRNA) transcriptome in human lung epithelial cells. Primary human bronchial epithelial (NHBE) cells differentiated at air-liquid interface were exposed to eCig liquid. Exposure of NHBE to any eCig liquid resulted in the induction of oxidative stress-response genes including GCLM, GCLC, GPX2, NQO1 and HO-1. Vaporization of, and/or the presence of nicotine in, eCig liquid was associated with a greater response. We identified 578 miRNAs dysregulated by eCig exposure in NHBE, and 125 miRNA affected by vaporization of eCig liquid. Nicotine containing eCig vapor displayed the most profound effects upon miRNA expression. We selected 8 miRNAs (29A, 140, 126, 374A, 26A-2, 147B, 941 and 589) for further study. We validated increased expression of multiple miRNAs, including miR126, following eCig exposure. We also found significant reduction in the expression of two miR126 target genes, MYC and MRGPRX3, following exposure. These data demonstrated that eCig exposure has profound effects upon gene expression in human lung epithelial cells, some of which are epigenetically programmed at the level of miRNA regulation.

MicroRNA expression profiling defines the impact of electronic cigarettes on human airway epithelial cells

While all forms of tobacco exposure have negative health effects, the significance of exposure to electronic cigarettes (eCig) is not fully understood. Here, we studied the global effects of eCig on the micro RNA (miRNA) transcriptome in human lung epithelial cells. Primary human bronchial epithelial (NHBE) cells differentiated at air-liquid interface were exposed to eCig liquid. Exposure of NHBE to any eCig liquid resulted in the induction of oxidative stress-response genes including GCLM, GCLC, GPX2, NQO1 and HO-1. Vaporization of, and/or the presence of nicotine in, eCig liquid was associated with a greater response. We identified 578 miRNAs dysregulated by eCig exposure in NHBE, and 125 miRNA affected by vaporization of eCig liquid. Nicotine containing eCig vapor displayed the most profound effects upon miRNA expression. We selected 8 miRNAs (29A, 140, 126, 374A, 26A-2, 147B, 941 and 589) for further study. We validated increased expression of multiple miRNAs, including miR126, following eCig exposure. We also found significant reduction in the expression of two miR126 target genes, MYC and MRGPRX3, following exposure. These data demonstrated that eCig exposure has profound effects upon gene expression in human lung epithelial cells, some of which are epigenetically programmed at the level of miRNA regulation.

Molecular Impact of Electronic Cigarette Aerosol Exposure in Human Bronchial Epithelium

Little evidence is available regarding the physiological effects of exposure to electronic cigarette (ECIG) aerosol. We sought to determine the molecular impact of ECIG aerosol exposure in human bronchial epithelial cells (HBECs). Gene-expression profiling was conducted in primary grown at air liquid interface and exposed to 1 of 4 different ECIG aerosols, traditional tobacco cigarette (TCIG) smoke, or clean air. Findings were validated experimentally with quantitative polymerase chain reaction and a reactive oxygen species immunoassay. Using gene set enrichment analysis, signatures of in vitro ECIG exposure were compared with those generated from bronchial epithelial brushings of current TCIG smokers and former TCIG smokers currently using ECIGs. We found 546 genes differentially expressed across the ECIG, TCIG, and air-exposed groups of HBECs (ANOVA; FDR q < .05; fold change > 1.5). A subset of these changes were shared between TCIG- and ECIG-exposed HBECs. ECIG exposure induced genes involved in oxidative and xenobiotic stress pathways and increased a marker of reactive oxygen species production in a dose-dependent manner. ECIG exposure decreased expression of genes involved in cilia assembly and movement. Furthermore, gene-expression differences observed in vitro were concordant with differences observed in airway epithelium collected from ECIG users (q < .01). In summary, our data suggest that ECIG aerosol can induce gene-expression changes in bronchial airway epithelium in vitro, some of which are shared with TCIG smoke. These changes were generally less pronounced than the effects of TCIG exposure and were more pronounced in ECIG products containing nicotine than those without nicotine. Our data further suggest that the gene-expression alterations seen with the in vitro exposure system reflects the physiological effects experienced in vivo by ECIG users.

Identification of gene expression signature for cigarette smoke exposure response--from man to mouse

Gene expression profiling data can be used in toxicology to assess both the level and impact of toxicant exposure, aligned with a vision of 21st century toxicology. Here, we present a whole blood-derived gene signature that can distinguish current smokers from either nonsmokers or former smokers with high specificity and sensitivity. Such a signature that can be measured in a surrogate tissue (whole blood) may help in monitoring smoking exposure as well as discontinuation of exposure when the primarily impacted tissue (e.g., lung) is not readily accessible. The signature consisted of LRRN3, SASH1, PALLD, RGL1, TNFRSF17, CDKN1C, IGJ, RRM2, ID3, SERPING1, and FUCA1. Several members of this signature have been previously described in the context of smoking. The signature translated well across species and could distinguish mice that were exposed to cigarette smoke from ones exposed to air only or had been withdrawn from cigarette smoke exposure. Finally, the small signature of only 11 genes could be converted into a polymerase chain reaction-based assay that could serve as a marker to monitor compliance with a smoking abstinence protocol.

Tumor Exosomal RNAs Promote Lung Pre-metastatic Niche Formation by Activating Alveolar Epithelial TLR3 to Recruit Neutrophils

The pre-metastatic niche educated by primary tumor-derived elements contributes to cancer metastasis. However, the role of host stromal cells in metastatic niche formation and organ-specific metastatic tropism is not clearly defined. Here, we demonstrate that lung epithelial cells are critical for initiating neutrophil recruitment and lung metastatic niche formation by sensing tumor exosomal RNAs via Toll-like receptor 3 (TLR3). TLR3-deficient mice show reduced lung metastasis in the spontaneous metastatic models. Mechanistically, primary tumor-derived exosomal RNAs, which are enriched in small nuclear RNAs, activate TLR3 in lung epithelial cells, consequently inducing chemokine secretion in the lung and promoting neutrophil recruitment. Identification of metastatic axis of tumor exosomal RNAs and host lung epithelial cell TLR3 activation provides potential targets to control cancer metastasis to the lung.

Transcriptome sequencing reveals e-cigarette vapor and mainstream-smoke from tobacco cigarettes activate different gene expression profiles in human bronchial epithelial cells

Electronic cigarettes (e-cigarettes) generate an aerosol vapor (e-vapor) thought to represent a less risky alternative to main stream smoke (MSS) of conventional tobacco cigarettes. RNA-seq analysis was used to examine the transcriptomes of differentiated human bronchial epithelial (HBE) cells exposed to air, MSS from 1R5F tobacco reference cigarettes, and e-vapor with and without added nicotine in an in vitro air-liquid interface model for cellular exposure. Our results indicate that while e-vapor does not elicit many of the cell toxicity responses observed in MSS-exposed HBE cells, e-vapor exposure is not benign, but elicits discrete transcriptomic signatures with and without added nicotine. Among the cellular pathways with the most significantly enriched gene expression following e-vapor exposure are the phospholipid and fatty acid triacylglycerol metabolism pathways. Our data suggest that alterations in cellular glycerophopholipid biosynthesis are an important consequences of e-vapor exposure. Moreover, the presence of nicotine in e-vapor elicits a cellular response distinct from e-vapor alone including alterations of cytochrome P450 function, retinoid metabolism, and nicotine catabolism. These studies establish a baseline for future analysis of e-vapor and e-vapor additives that will better inform the FDA and other governmental bodies in discussions of the risks and future regulation of these products.

Persistence of smoking-induced dysregulation of miRNA expression in the small airway epithelium despite smoking cessation

Even after quitting smoking, the risk of the development of chronic obstructive pulmonary disease (COPD) and lung cancer remains significantly higher compared to healthy nonsmokers. Based on the knowledge that COPD and most lung cancers start in the small airway epithelium (SAE), we hypothesized that smoking modulates miRNA expression in the SAE linked to the pathogenesis of smoking-induced airway disease, and that some of these changes persist after smoking cessation. SAE was collected from 10^th to 12^th order bronchi using fiberoptic bronchoscopy. Affymetrix miRNA 2.0 arrays were used to assess miRNA expression in the SAE from 9 healthy nonsmokers and 10 healthy smokers, before and after they quit smoking for 3 months. Smoking status was determined by urine nicotine and cotinine measurement. There were significant differences in the expression of 34 miRNAs between healthy smokers and healthy nonsmokers (p<0.01, fold-change >1.5), with functions associated with lung development, airway epithelium differentiation, inflammation and cancer. After quitting smoking for 3 months, 12 out of the 34 miRNAs did not return to normal levels, with Wnt/β-catenin signaling pathway being the top identified enriched pathway of the target genes of the persistent dysregulated miRNAs. In the context that many of these persistent smoking-dependent miRNAs are associated with differentiation, inflammatory diseases or lung cancer, it is likely that persistent smoking-related changes in SAE miRNAs play a role in the subsequent development of these disorders.

Airway epithelium interactions with aeroallergens: role of secreted cytokines and chemokines in innate immunity

Airway epithelial cells are the first line of defense against the constituents of the inhaled air, which include allergens, pathogens, pollutants, and toxic compounds. The epithelium not only prevents the penetration of these foreign substances into the interstitium, but also senses their presence and informs the organism’s immune system of the impending assault. The epithelium accomplishes the latter through the release of inflammatory cytokines and chemokines that recruit and activate innate immune cells at the site of assault. These epithelial responses aim to eliminate the inhaled foreign substances and minimize their detrimental effects to the organism. Quite frequently, however, the innate immune responses of the epithelium to inhaled substances lead to chronic and high level release of pro-inflammatory mediators that may mediate the lung pathology seen in asthma. The interactions of airway epithelial cells with allergens will be discussed with particular focus on interactions-mediated epithelial release of cytokines and chemokines and their role in the immune response. As pollutants are other major constituents of inhaled air, we will also discuss how pollutants may alter the responses of airway epithelial cells to allergens.

Biomarkers of tobacco smoke exposure

Diseases and death caused by exposure to tobacco smoke have become the single most serious preventable public health concern. Thus, biomarkers that can monitor tobacco exposure and health effects can play a critical role in tobacco product regulation and public health policy. Biomarkers of exposure to tobacco toxicants are well established and have been used in population studies to establish public policy regarding exposure to second-hand smoke, an example being the nicotine metabolite cotinine, which can be measured in urine. Biomarkers of biological response to tobacco smoking range from those indicative of inflammation to mRNA and microRNA patterns related to tobacco use and/or disease state. Biomarkers identifying individuals with an increased risk for a pathological response to tobacco have also been described. The challenge for any novel technology or biomarker is its translation to clinical and/or regulatory application, a process that requires first technical validation of the assay and then careful consideration of the context the biomarker assay may be used in the regulatory setting. Nonetheless, the current efforts to investigate new biomarker of tobacco smoke exposure promise to offer powerful new tools in addressing the health hazards of tobacco product use. This review will examine such biomarkers, albeit with a focus on those related to cigarette smoking.

Application of a modified gaseous exposure system to the in vitro toxicological assessment of tobacco smoke toxicants

Tobacco smoke is a complex mixture of over 6,000 individual chemical constituents. Approximately 150 of these have been identified as 'tobacco smoke toxicants' due to their known toxicological effects. A number of these toxicants are present in the gaseous phase of tobacco smoke. This presents a technical challenge when assessing the toxicological effects of these chemicals in vitro. We have adapted a commercially available tobacco smoke exposure system to enable the assessment of the contribution of individual smoke toxicants to the overall toxicological effects of whole mainstream cigarette smoke (WS). Here we present a description of the exposure system and the methodology used. We use the example of a gaseous tobacco smoke toxicant, ethylene oxide (EtO), a Group 1 IARC carcinogen and known mutagen, to illustrate how this methodology can be applied to the assessment of genotoxicity of gaseous chemicals in the context of WS. In the present study we found that EtO was positive in Salmonella typhimurium strain YG1042, a strain that is sensitive to tobacco smoke. However, EtO did not increase the mutagenicity of the WS mixture when it was added at greatly higher concentrations than those found typically in WS. The findings presented here demonstrate the suitability of this exposure system for the assessment of the mutagenic potential of gases in vitro. Whilst we have focused on tobacco smoke toxicants, this system has broad application potential in studying the biological effects of exposure to a wide range of gaseous compounds that are present within complex aerosol mixtures.

A review of in vitro cigarette smoke exposure systems

In vitro test methods may be vital in understanding tobacco smoke, the main toxicants responsible for adverse health effects, and elucidating disease mechanisms. There is a variety of 'whole smoke' exposure systems available for the generation, dilution and delivery of tobacco smoke in vitro; these systems can be procured commercially from well-known suppliers or can be bespoke set-ups. These exposure technologies aim to ensure that there are limited changes in the tobacco smoke aerosol from generation to exposure. As the smoke aerosol is freshly generated, interactions in the smoke fractions are captured in any subsequent in vitro analysis. Of the commercially available systems, some have been characterised more than others in terms of published scientific literature and developed biological endpoints. Others are relatively new to the scientific field and are still establishing their presence. In addition, bespoke systems are widely used and offer a more flexible approach to the challenges of tobacco smoke exposure. In this review, the authors present a summary of the major tobacco smoke exposure systems available and critically review their function, set-up and application for in vitro exposure scenarios. All whole smoke exposure systems have benefits and limitations, often making it difficult to make comparisons between set-ups and the data obtained from such diverse systems. This is where exposure and dose measurements can add value and may be able to provide a platform on which comparisons can be made. The measurement of smoke dose, as an emerging field of research, is therefore also discussed and how it may provide valuable and additional data to support existing whole smoke exposure set-ups and aid validation efforts.

Transcriptome alterations induced by cigarette smoke

Cigarette smoke alters the transcriptome of multiple tissues; those directly exposed to toxic products and those exposed to circulating components and metabolic products of tobacco smoke. In most tissues and organs that have been studied, the smoking transcriptome is characterized by increased expression of antioxidant and xenobiotic genes as well as a wide spectrum of inflammation-related genes, and potential oncogenic genes. Smoking is associated with an increased incidence of cancer in a number of organs both those directly exposed (lungs and airways) and those indirectly exposed (bladder, liver, pancreas). Individual transcriptomic responses vary, based to some degree on as yet to be clarified genetic factors, and likely how and what the individual has smoked. The complexity of individual responses to tobacco exposure and of smoking-related cancers in various organs is beginning to be revealed in transcriptomic and whole genome sequencing studies, of both tumors and cytologically normal appearing cells that have been exposed to cigarette smoke or its products creating a genomic "field of injury." The recent application of next generation sequencing to defining the transcriptome alterations induced by cigarette smoke holds the promise of discovering new approaches to personalized prevention and treatment of smoking-related lung diseases in the future.

Acute effects of cigarette smoke on three-dimensional cultures of normal human oral mucosa

CONTEXT

Human oral mucosa is the combustion chamber of cigarette, but scanty evidence is available about the early smoke effects.

OBJECTIVE

The present work aimed at evaluating from a morphological point of view whole smoke early effects on epithelial intercellular adhesion and keratinocyte terminal differentiation in a three-dimensional model of human oral mucosa.

MATERIALS AND METHODS

Biopsies of keratinized oral mucosa of healthy nonsmoking women (n = 5) were collected. After culturing in a Transwell system, one fragment of each biopsy was exposed to the smoke of one single cigarette; the remnant represented the internal control. The distribution of epithelial differentiation markers (keratin-10, K10, and keratin-14, K14, for suprabasal and basal cells respectively), desmosomes (desmoglein-1, desmoglein-3), tight junctions (occludin), adherens junctions (E-cadherin, β-catenin), and apoptotic cells (p53, caspase 3) were evaluated by immunofluorescence.

RESULTS

Quantitative analysis of K14 immunolabeling revealed an overexpression in the suprabasal layers as early as 3 h after smoke exposure, without impairment of the epithelial junctional apparatus and apoptosis induction.

DISCUSSION AND CONCLUSION

These results suggested that the first significant response to cigarette smoke came from the basal and suprabasal layers of the human oral epithelium. The considered model maintained the three-dimensional arrangement of the human mucosa in the oral cavity and mimicked the inhalation/exhalation cycle during the exposure to cigarette smoke, offering a good possibility to extrapolate the reported observations to humans.

Cigarette smoke exposure induces CFTR internalization and insolubility, leading to airway surface liquid dehydration

Cigarette smoke (CS) exposure induces mucus obstruction and the development of chronic bronchitis (CB). While many of these responses are determined genetically, little is known about the effects CS can exert on pulmonary epithelia at the protein level. We, therefore, tested the hypothesis that CS exerts direct effects on the CFTR protein, which could impair airway hydration, leading to the mucus stasis characteristic of both cystic fibrosis and CB. In vivo and in vitro studies demonstrated that CS rapidly decreased CFTR activity, leading to airway surface liquid (ASL) volume depletion (i.e., dehydration). Further studies revealed that CS induced internalization of CFTR. Surprisingly, CS-internalized CFTR did not colocalize with lysosomal proteins. Instead, the bulk of CFTR shifted to a detergent-resistant fraction within the cell and colocalized with the intermediate filament vimentin, suggesting that CS induced CFTR movement into an aggresome-like, perinuclear compartment. To test whether airway dehydration could be reversed, we used hypertonic saline (HS) as an osmolyte to rehydrate ASL. HS restored ASL height in CS-exposed, dehydrated airway cultures. Similarly, inhaled HS restored mucus transport and increased clearance in patients with CB. Thus, we propose that CS exposure rapidly impairs CFTR function by internalizing CFTR, leading to ASL dehydration, which promotes mucus stasis and a failure of mucus clearance, leaving smokers at risk for developing CB. Furthermore, our data suggest that strategies to rehydrate airway surfaces may provide a novel form of therapy for patients with CB.