RESUMO
Waterpipe (also called hookah, shisha, or narghile) smoking is a common form of tobacco use in the Middle East. Its use is becoming more prevalent in Western societies, especially among young adults as an alternative form of tobacco use to traditional cigarettes. While the risk to cigarette smoking is well documented, the risk to waterpipe smoking is not well defined with limited information on its health impact at the epidemiologic, clinical and biologic levels with respect to lung disease. Based on the knowledge that airway epithelial cell DNA methylation is modified in response to cigarette smoke and in cigarette smoking-related lung diseases, we assessed the impact of light-use waterpipe smoking on DNA methylation of the small airway epithelium (SAE) and whether changes in methylation were linked to the transcriptional output of the cells. Small airway epithelium was obtained from 7 nonsmokers and 7 light-use (2.6 ± 1.7 sessions/wk) waterpipe-only smokers. Genome-wide comparison of SAE DNA methylation of waterpipe smokers to nonsmokers identified 727 probesets differentially methylated (fold-change >1.5, p<0.05) representing 673 unique genes. Dominant pathways associated with these epigenetic changes include those linked to G-protein coupled receptor signaling, aryl hydrocarbon receptor signaling and xenobiotic metabolism signaling, all of which have been associated with cigarette smoking and lung disease. Of the genes differentially methylated, 11.3% exhibited a corresponding significant (p<0.05) change in gene expression with enrichment in pathways related to regulation of mRNA translation and protein synthesis (eIF2 signaling and regulation of eIF4 and p70S6K signaling). Overall, these data demonstrate that light-use waterpipe smoking is associated with epigenetic changes and related transcriptional modifications in the SAE, the cell population demonstrating the earliest pathologic abnormalities associated with chronic cigarette smoking.
Assuntos
Epigênese Genética , Epitélio/metabolismo , Fumar , Adulto , Brônquios/metabolismo , DNA/genética , DNA/isolamento & purificação , DNA/metabolismo , Metilação de DNA , Regulação para Baixo , Feminino , Genoma Humano , Humanos , Masculino , RNA/genética , RNA/isolamento & purificação , RNA/metabolismo , Receptores de Hidrocarboneto Arílico/metabolismo , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Regulação para CimaRESUMO
Basal cells (BC) are the stem/progenitor cells of the human airway epithelium capable of differentiating into secretory and ciliated cells. Notch signaling activation increases BC differentiation into secretory cells, but the role of individual Notch ligands in regulating this process in the human airway epithelium is largely unknown. The objective of this study was to define the role of the Notch ligand JAG1 in regulating human BC differentiation. JAG1 over-expression in BC increased secretory cell differentiation, with no effect on ciliated cell differentiation. Conversely, knockdown of JAG1 decreased expression of secretory cell genes. These data demonstrate JAG1-mediated Notch signaling regulates differentiation of BC into secretory cells.
Assuntos
Diferenciação Celular/genética , Epitélio/metabolismo , Proteína Jagged-1/genética , Receptores Notch/genética , Mucosa Respiratória/metabolismo , Transdução de Sinais/genética , Western Blotting , Células Epiteliais/citologia , Células Epiteliais/metabolismo , Imunofluorescência , Perfilação da Expressão Gênica/métodos , Humanos , Proteína Jagged-1/metabolismo , Interferência de RNA , Receptores Notch/metabolismo , Mucosa Respiratória/citologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de RNA/métodos , Células-Tronco/citologia , Células-Tronco/metabolismoRESUMO
BACKGROUND: Aging involves multiple biologically complex processes characterized by a decline in cellular homeostasis over time leading to a loss and impairment of physiological integrity and function. Specific cellular hallmarks of aging include abnormal gene expression patterns, shortened telomeres and associated biological dysfunction. Like all organs, the lung demonstrates both physiological and structural changes with age that result in a progressive decrease in lung function in healthy individuals. Cigarette smoking accelerates lung function decline over time, suggesting smoking accelerates aging of the lung. Based on this data, we hypothesized that cigarette smoking accelerates the aging of the small airway epithelium, the cells that take the initial brunt of inhaled toxins from the cigarette smoke and one of the primary sites of pathology associated with cigarette smoking. METHODS: Using the sensitive molecular parameters of aging-related gene expression and telomere length, the aging process of the small airway epithelium was assessed in age matched healthy nonsmokers and healthy smokers with no physical manifestation of lung disease or abnormalities in lung function. RESULTS: Analysis of a 73 gene aging signature demonstrated that smoking significantly dysregulates 18 aging-related genes in the small airway epithelium. In an independent cohort of male subjects, smoking significantly reduced telomere length in the small airway epithelium of smokers by 14% compared to nonsmokers. CONCLUSION: These data provide biologic evidence that smoking accelerates aging of the small airway epithelium.
