Unknown,Transcriptomics,Genomics,Proteomics

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Chronic Cigarette Smoke Exposure Results in Coordinated Methylation and Gene Expression Changes in Human Alveolar Macrophages

ABSTRACT: Cigarette smoking is the leading cause of emphysema in the United States. Alveolar macrophages play a critical role in the inflammation-mediated remodeling of the lung parenchyma in emphysema. However, the exact gene pathways and the role of DNA methylation in moderating this pathological transformation are not known. In order to more exactly understand this process, we compared genome-wide expression and methylation signatures of alveolar macrophages isolated from heavy smokers with those isolated from non-smoking controls. We found enrichment of differential methylation in genes from immune system and inflammatory pathways as determined by standard pathway analysis. Consistent with recent findings, significant methylation changes were particularly enriched in the areas flanking CpG islands (CpG shores). Analysis of matching gene expression data demonstrated a parallel enrichment for changes in immune system and inflammatory pathways. We conclude that alveolar macrophages from the lungs of smokers demonstrate coordinated changes in DNA methylation and gene expression that link to inflammation pathways. We suggest that further studies of DNA methylation in immune and inflammation-related gene expression are needed to understand the pathogenesis of emphysema and other smoking-related diseases. Expression analysis of 13 smokers vs. 10 non-smokers on the Affymetrix Exon Array. This submission represents the expression component of the study.

ORGANISM(S): Homo sapiens

SUBMITTER: Thomas Bair

PROVIDER: E-GEOD-27002 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Cigarette smoking is the leading cause of the respiratory diseases collectively known as chronic obstructive pulmonary disease (COPD). While the pathogenesis of COPD is complex, there is abundant evidence that alveolar macrophages (AM) play an important role. Based on the concept that COPD is a slow-progressing disorder likely involving multiple mediators released by AM activated by cigarette smoke, the present study focuses on the identification of previously unrecognized genes that may be linked to early events in the molecular pathogenesis of COPD, as opposed to factors associated with the presence of disease. To accomplish this, microarray analysis using Affymetrix microarrays was used to carry out an unbiased survey of the differences in gene expression profiles in the AM of phenotypically normal, ~20 pack-yr smokers compared to healthy non-smokers. Although smoking did not alter the global gene expression pattern of AM, 75 genes were modulated by smoking, with 40 genes up-regulated and 35 down-regulated in the AM of smokers compared to non-smokers. Most of these genes belong to the functional categories of immune/inflammatory response, cell adhesion and extracellular matrix, proteolysis and antiproteolysis, lysosomal function, antioxidant-related, signal transduction and regulation of transcription. Of these 75 genes, 69 have not been previously recognized to be up- or down-regulated in alveolar macrophages in association with smoking or COPD, including genes coding for proteins belonging to all of the above categories, and others belonging to various functional categories or of unknown function. These observations suggest that gene expression responses of alveolar macrophages associated with the stress of cigarette smoking are more complex than previously thought, and offer a variety of new insights into the complex pathogenesis of smoking-induced lung diseases. Experiment Overall Design: 5 non smokers and 5 smokers Experiment Overall Design: Alveolar macrophages were obtained from bronchoalveolar lavage

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.

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Chronic Cigarette Smoke Exposure Results in Coordinated Methylation and Gene Expression Changes in Human Alveolar Macrophages

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