Down-regulation of the Notch Pathway in Human Airway Epithelium in Association with Smoking and Chronic Obstructive Pulmonary Disease

• Published in: American journal of respiratory and critical care medicine Vol. 179; no. 6; pp. 457 - 466
• Main Authors: Tilley, Ann E, Harvey, Ben-Gary, Heguy, Adriana, Hackett, Neil R, Wang, Rui, O'Connor, Timothy P, Crystal, Ronald G
• Format: Journal Article
• Language: English
• Published: New York, NY Am Thoracic Soc 15.03.2009; American Thoracic Society
• Subjects: Adult; Adults; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; B. Chronic Obstructive Pulmonary Disease; Basic Helix-Loop-Helix Transcription Factors - genetics; Basic Helix-Loop-Helix Transcription Factors - metabolism; Biological and medical sciences; Calcium-Binding Proteins - genetics; Calcium-Binding Proteins - metabolism; Case-Control Studies; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Chronic obstructive pulmonary disease; Chronic obstructive pulmonary disease, asthma; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Down-Regulation; Epithelium - metabolism; Female; Gene Expression; Homeodomain Proteins - genetics; Homeodomain Proteins - metabolism; Humans; Immunohistochemistry; Intensive care medicine; Intercellular Signaling Peptides and Proteins - genetics; Intercellular Signaling Peptides and Proteins - metabolism; Jagged-1 Protein; Ligands; Male; Medical sciences; Membrane Proteins - genetics; Membrane Proteins - metabolism; Middle Aged; Pneumology; Polymerase chain reaction; Proteins; Pulmonary Disease, Chronic Obstructive - genetics; Pulmonary Disease, Chronic Obstructive - metabolism; Receptors, Notch - genetics; Receptors, Notch - metabolism; Repressor Proteins - genetics; Repressor Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Serrate-Jagged Proteins; Smoking; Smoking - genetics; Smoking - metabolism; Stem cells; Transcription Factor HES-1; Transcription factors; Transcription Factors - genetics; Transcription Factors - metabolism; Human; Lung disease; Intensive care; microarray analysis; Respiratory disease; Tobacco smoking; basic helix-loop-helix transcription factors; Epithelium; Gene expression; delta-like ligand; Notch receptors; Bronchus disease; Chronic obstructive pulmonary disease; Transcription factor; Resuscitation
• ISSN: 1073-449X; 1535-4970; 1535-4970
• DOI: 10.1164/rccm.200705-795OC

The airway epithelium of smokers is subject to a variety of mechanisms of injury with consequent modulation of epithelial regeneration and disordered differentiation. Several signaling pathways, including the Notch pathway, control epithelial differentiation in lung morphogenesis, but little is known about the role of these pathways in adults. We tested the hypotheses that Notch-related genes are expressed in the normal nonsmoker small airway epithelium of human adults, and that Notch-related gene expression is down-regulated in healthy smokers and smokers with chronic obstructive pulmonary disease (COPD). We used microarray technology to evaluate the expression of 55 Notch-related genes in the small airway epithelium of nonsmokers. We used TaqMan quantitative polymerase chain reaction (PCR) to confirm the expression of key genes and we used immunohistochemistry to assess the expression of Notch-related proteins in the airway epithelium. Changes in expression of Notch genes in healthy smokers and smokers with COPD compared with nonsmokers were evaluated by PCR. Microarray analysis demonstrated that 45 of 55 Notch-related genes are expressed in the small airway epithelium of adults. TaqMan PCR confirmed the expression of key genes with highest expression of the ligand DLL1, the receptor NOTCH2, and the downstream effector HES1. Immunohistochemistry demonstrated the expression of Jag1, Notch2, Hes1, and Hes5 in airway epithelium. Several Notch ligands, receptors, and downstream effector genes were down-regulated in smokers, with more genes down-regulated in smokers with COPD than in healthy smokers. These observations are consistent with the hypothesis that the Notch pathway likely plays a role in the human adult airway epithelium, with down-regulation of Notch pathway gene expression in association with smoking and COPD.