Project description:Rationale: Even after quitting smoking, the risk of the development of chronic obstructive pulmonary disease (COPD) and lung cancer remains significantly higher compared to never-smokers. Objectives: 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. Methods: SAE was collected from 10th to 12th order bronchi using fiberoptic bronchoscopy. Affymetrix miRNA 2.0 arrays were used to assess miRNA expression in the SAE from 10 healthy never-smokers and 10 healthy smokers, before and after they quit for 3 months. Smoking status was determined by urine nicotine and cotinine measurement. Results: There were significant differences in the expression of 34 miRNAs between healthy smokers and healthy never-smokers (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 the top enriched pathway of the target genes of the persistent deregulated miRNAs. Conclusions: In the context that many of these persistent smoking-dependent miRNAs are associated with differentiation, inflammation diseases or lung cancer, it is likely that persistent smoking-related changes in small airway epithelium miRNAs play a role in the subsequent development of these disorders. MicroRNA profiling identified 34 miRNAs up-regulated by cigarette smoking in human small airway epithelium. Even after quitting smoking for 3 months, 12 miRNAs didnât return to normal level.
Project description:Rationale: Even after quitting smoking, the risk of the development of chronic obstructive pulmonary disease (COPD) and lung cancer remains significantly higher compared to never-smokers. Objectives: 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. Methods: SAE was collected from 10th to 12th order bronchi using fiberoptic bronchoscopy. Affymetrix miRNA 2.0 arrays were used to assess miRNA expression in the SAE from 10 healthy never-smokers and 10 healthy smokers, before and after they quit for 3 months. Smoking status was determined by urine nicotine and cotinine measurement. Results: There were significant differences in the expression of 34 miRNAs between healthy smokers and healthy never-smokers (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 the top enriched pathway of the target genes of the persistent deregulated miRNAs. Conclusions: In the context that many of these persistent smoking-dependent miRNAs are associated with differentiation, inflammation diseases or lung cancer, it is likely that persistent smoking-related changes in small airway epithelium miRNAs play a role in the subsequent development of these disorders.
Project description:The initial site of smoking-induced lung disease is the small airway epithelium, which is difficult and time consuming to sample by fiberoptic bronchoscopy. We developed a rapid, office-based procedure to obtain trachea epithelium without conscious sedation from healthy nonsmokers (n=26) and healthy smokers (n=19, 27 ± 15 pack-yr). Gene expression differences [fold-change >1.5, p< 0.01, Benjamini-Hochberg correction] were assessed with Affymetrix microarrays. 1,057 probe sets were differentially expressed in healthy smokers vs nonsmokers, representing >500 genes. Trachea gene expression was compared to an independent group of small airway epithelial samples (n=23 healthy nonsmokers, n=19 healthy smokers, 25 ± 12 pack-yr). The trachea epithelium is more sensitive to smoking, responding with 3-fold more differentially-expressed genes than small airway epithelium. The trachea transcriptome paralleled the small airway epithelium, with 156 of 167 (93%) genes that are significantly up- and down-regulated by smoking in the small airway epithelium showing similar direction and magnitude of response to smoking in the trachea. Trachea epithelium can be obtained without conscious sedation, representing a less invasive surrogate “canary” for smoking-induced changes in the small airway epithelium. This should prove useful in epidemiologic studies correlating gene expression with clinical outcome in assessing smoking-induced lung disease.
Project description:The initial site of smoking-induced lung disease is the small airway epithelium, which is difficult and time consuming to sample by fiberoptic bronchoscopy. We developed a rapid, office-based procedure to obtain trachea epithelium without conscious sedation from healthy nonsmokers (n=26) and healthy smokers (n=19, 27 ± 15 pack-yr). Gene expression differences [fold-change >1.5, p< 0.01, Benjamini-Hochberg correction] were assessed with Affymetrix microarrays. 1,057 probe sets were differentially expressed in healthy smokers vs nonsmokers, representing >500 genes. Trachea gene expression was compared to an independent group of small airway epithelial samples (n=23 healthy nonsmokers, n=19 healthy smokers, 25 ± 12 pack-yr). The trachea epithelium is more sensitive to smoking, responding with 3-fold more differentially-expressed genes than small airway epithelium. The trachea transcriptome paralleled the small airway epithelium, with 156 of 167 (93%) genes that are significantly up- and down-regulated by smoking in the small airway epithelium showing similar direction and magnitude of response to smoking in the trachea. Trachea epithelium can be obtained without conscious sedation, representing a less invasive surrogate “canary” for smoking-induced changes in the small airway epithelium. This should prove useful in epidemiologic studies correlating gene expression with clinical outcome in assessing smoking-induced lung disease. Experiment Overall Design: Tracheal gene expression: matched group of small airway epithelial samples (n=23 healthy non-smokers, n= 19 healthy smokers)
Project description:The Wnt pathway plays a central role in controlling differentiation of epithelial tissues; when Wnt is on, differentiation is suppressed, but when Wnt is off, differentiation is allowed to proceed. Based on this concept, we hypothesized that expression of key genes in the Wnt pathway are suppressed in the human airway epithelium under the stress of cigarette smoking, a stress associated with dysregulation of the differentiated state of the airway epithelium. For this purpose, HG-U133 Plus 2.0 microarrays were used to assess the expression of Wnt-related genes in the small airway (10th-12th generation) epithelium (SAE) obtained via bronchoscopy and brushing of healthy nonsmokers (n=47), healthy smokers (n=58), and smokers with established COPD (n=22). With expression defined as present in >20% of samples, microarray analysis demonstrated that 35 of 57 known Wnt-related genes are expressed in the adult SAE. Wnt pathway downstream targets β-catenin (p<0.05) and the transcription factor 7-like 1 were down-regulated in healthy smokers, and smokers with COPD, as were a number of Wnt target genes, including VEGFA, CCND1, MMP7, CLDN1, SOX9, RHOU (all p<0.05 compared to healthy nonsmokers). As a mechanism to explain this broad, smoking-induced suppression of the Wnt pathway, we assessed expression of the DKK and SFRP families, extracellular regulators that suppress the Wnt pathway. Among these, secreted frizzled-related protein 2 (SFRP2), was up-regulated 4.3-fold (p<0.0001) in healthy smokers and 4.9-fold (p<0.0001) in COPD smokers, an observation confirmed by TaqMan Real-time PCR. AT the protein levels, Western analysis demonstrated SFRP2 up-regulation, and immunohistochemistry demonstrated that the smoking-induced SFRP2 upregulation occurred in differentiated ciliated cells. Finally, cigarette smoke extract mediated up-regulation of SFRP2 and downregulation of Wnt target genes in airway epithelial cells in vitro. These observations are consistent with the hypothesis that the Wnt pathway plays a role in airway epithelial cell differentiation in the adult human airway epithelium, with smoking associated with down-regulation of Wnt pathway, contributing to the dysregulation of airway epithelial differentiation observed in the smoking-related airway disorders. Affymetrix arrays were used to assess gene expression data of genes in the Wnt pathway in small airway epithelium obtained by fiberoptic bronchoscopy of 47 healthy non-smokers and 58 healthy smokers and 22 smokers with COPD.
Project description:The apical junctional complex (AJC), composed of tight junctions and adherens junctions, is essential for maintaining epithelial barrier function. Since cigarette smoking and chronic obstructive pulmonary disease (COPD), the major smoking-induced disease, are both associated with increased lung epithelial permeability, we hypothesized that smoking alters the transcriptional program regulating AJC integrity in the small airway epithelium (SAE), the primary site of pathological changes in COPD. Transcriptome analysis revealed a global down-regulation of physiological AJC gene expression in the SAE of healthy smokers (n=53) compared to healthy nonsmokers (n=59), an observation associated with changes in molecular pathways regulating epithelial differentiation such as PTEN signaling and accompanied by induction of cancer-related AJC genes. Genome-wide co-expression analysis identified a smoking-sensitive AJC transcriptional network. The overall expression of AJC-associated genes was further decreased in COPD smokers (n=23). Exposure of human airway epithelial cells to cigarette smoke extract in vitro resulted in down-regulation of several AJC-related genes, accompanied by decreased transepithelial resistance. Thus, cigarette smoking alters the AJC gene expression architecture in the human airway epithelium, providing a molecular basis for the dysregulation of airway epithelial barrier function during the development of smoking-induced lung disease. The apical junctional complex (AJC), composed of tight junctions and adherens junctions, is essential for maintaining epithelial barrier function. Since cigarette smoking and chronic obstructive pulmonary disease (COPD), the major smoking-induced disease, are both associated with increased lung epithelial permeability, we hypothesized that smoking alters the transcriptional program regulating AJC integrity in the small airway epithelium (SAE), the primary site of pathological changes in COPD. In this study, microarray analysis of the SAE obtained from 53 healthy nonsmokers, 59 healthy smokers, and 23 smokers with COPD was performed to determine physiological AJC gene expression architecture in the SAE and its modification by cigarette smoking and during the development of COPD.
Project description:The earliest morphologic evidence of changes in the airways associated with chronic cigarette smoking is in the small airways. To help understand how smoking modifies small airway structure and function, we developed a strategy using fiberoptic bronchoscopy and brushing to sample the human small airway (10th-12th order) bronchial epithelium to assess gene expression (Affymetrix HG-U133A array) in phenotypically normal smokers (n=6, 24 ± 4 pack-yr) compared to matched non-smokers (n=5). Compared to samples from the large (2nd to 3rd order) bronchi, the small airway samples had a higher proportion of ciliated cells, but less basal, undifferentiated, and secretory cells. The small, but not large, airway samples included Clara cells, a cell found only in the small airway epithelium, and the small, but not the large, airway epithelium expressed genes for the surfactant apoproteins. Despite the fact that the smokers were phenotypically normal, analysis of the small airway epithelium of the smokers compared to the non-smokers demonstrated up- and -down-regulation of genes in multiple categories relevant to the pathogenesis of chronic obstructive lung disease (COPD), including genes coding for cytokines/innate immunity, apoptosis, pro-fibrosis, mucin, responses to oxidants and xenobiotics, antiproteases and general cellular processes. In the context that COPD starts in the small airways, these changes in gene expression in the small airway epithelium in phenotypically normal smokers are candidates for the development of therapeutic strategies to prevent the onset of COPD. Keywords: response to cigarette smoking
Project description:Although smoking-induced lung disease tends to be more common in the upper lobe, it is not known if this results from the skewed distribution of inhaled cigarette smoke or increased susceptibility of the upper lobes to these disorders. The distribution of inhaled cigarette smoke within the lung is complex, depending on lung pressure-volume relationships, gravity, individual smoking habits and the properties of the individual components of cigarette smoke. With the knowledge that the small airway epithelium is the earliest site of smoking-induced lung disease, and that the small airway epithelium is acutely sensitive to inhaled cigarette smoke with significant changes in the up- and down-regulation of hundreds of genes, we compared upper vs lower lobe gene expression in the small airway epithelium of the same cigarette smokers to determine if the gene expression patterns were similar or different. Active smokers (n=11) with early evidence of smoking-induced lung disease (normal spirometry but low diffusing capacity) underwent bronchoscopy and brushing of the small airway epithelium to compare upper vs lower lobe genome-wide gene expression assessed by microarray. Interestingly, cluster and principal component analysis demonstrated that, for each individual, the expression of the known small airway epithelium smoking-responsive genes were remarkably similar as upper vs lower lobe pairs, although, as expected, there were differences in the smoking-induced changes in gene expression from individual to individual. Thus, while there may be topographic differences in the distribution of cigarette smoke, sufficient smoke reaches the upper vs lower lobe small airway epithelium so that, within each smoker, the upper vs lower lobe gene expression are similar. These observations support the concept that the topographic differences in the occurrence of the smoking-induced lung diseases are likely secondary to topographic differences in the susceptibility of the upper vs lower lobes to cigarette smoke, not the topographic differences in distribution of inhaled cigarette smoke.
Project description:Smoking-induced lung disease is one of the most prevalent forms of lung disease but also one of the more diverse. Based on the phenotypic diversity caused by the same environmental stress, we hypothesized that smoking may induce changes in lung cell expression of genes that, with specific variants, are causative of monogenic lung disease, i.e., not that smoking induces a phenocopy of a genetic disease, but smoking may subtly modify the expression of genes known to be associated with genetic disorders with distinct lung disease phenotypes. To assess this hypothesis, and based on the knowledge that most smoking-related disease phenotypes start in the small airway epithelium, we asked: are the genes associated with the monogenic lung disorders expressed in the small airway epithelium, and if so, does smoking alter the expression of these genes? To accomplish this, we examined small airway epithelium expression of 92 genes known to be associated with 17 monogenic lung disorders in 230 samples of small airway epithelium (SAE) obtained from healthy nonsmokers and healthy smokers without any clinical evidence of disease. Of the 86 monogenic disorder-related genes we found expressed in the SAE, strikingly, 37 were significantly differentially expressed in normal smokers compared to normal nonsmokers (p<0.05, Benjamini-Hochberg correction for multiple comparisons). The data demonstrates that the effect of smoking on the transcriptome of small airway epithelium includes significantly altered regulation of the genes responsible for known monogenic disorders.
Project description:Disparate Oxidant-related Gene Expression of Human Small Airway Epithelium Compared to Autologous Alveolar Macrophages in Response to the In Vivo Oxidant Stress of Cigarette Smoking The oxidant burden of cigarette smoking induces lung cell dysfunction, and play a significant role in the pathogenesis of lung disease. Two cell populations directly exposed to the oxidants in cigarette smoke are the small airway epithelium and alveolar macrophages. Of these, the epithelium appears to be more vulnerable to smoking, becoming disordered in differentiation, repair and function, while alveolar macrophages become activated, without becoming diseased. In this context, we asked: for the same individuals, what is the baseline trancriptome of oxidant-related genes in small airway epithelium compared to alveolar macrophages and do the responses of the transcriptome of these 2 cell populations differ substantially to inhaled cigarette smoke? To address these questions we used microarray gene expression and TaqMan analysis to assess the gene expression profile of known oxidant-related genes in paired samples recovered by bronchoscopy from small airway epithelium and alveolar macrophages from the same healthy nonsmokers and normal smokers. Of the 155 oxidant-related genes surveyed, 122 (77%) were expressed in both cell populations in nonsmokers. However, of the genes expressed by both cell populations, oxidant related gene expression levels were higher in alveolar macrophages (67 genes, 43%) than small airway epithelium (37 genes, 24%). There were more oxidant-related genes uniquely expressed in the small airway epithelium (17%), than in alveolar macrophages (5%). In healthy smokers, the majority of oxidant-related genes were expressed in both cell populations, but there were marked differences in the numbers of oxidant-related genes that smoking up- or down-regulated. While smoking up-regulated 15 genes (10%) and down-regulated 7 genes (5%) in the small airway epithelium, smoking had far less effect on alveolar macrophages [only 4 (3%) genes up-regulated, and only 1 (0.6%) down-regulated]. Only a small number of smoking responsive oxidant-related genes overlapped between the two cell types (2 up-regulated, and no down-regulated genes). Consistent with this observation, pathway analysis of smoking-responsive genes in the small airway epithelium showed oxidant-related pathways dominated, but in alveolar macrophages immune-response pathways dominated. Thus, the responses of the oxidant-related transcriptome of cells with an identical genome and exposed to the same oxidant stress of cigarette smoking are very different, with responses of oxidant-related genes of alveolar macrophages far more subdued than that of small airway epithelium, consistent with the clinical observation that, while the small airway epithelium is vulnerable, alveolar macrophages are not "diseased" in response to the oxidant stress of cigarette smoking. Gene expression profiles of known oxidant-related genes in paired samples recovered by bronchoscopy from small airway epithelium and alveolar macrophages from the same healthy nonsmokers and normal smokers.