title: Cigarette smoke extract induces a phenotypic shift in epithelial cells; involvement of HIF1α in mesenchymal transition.
abstract: In COPD, matrix remodeling contributes to airflow limitation. Recent evidence suggests that next to fibroblasts, the process of epithelial-mesenchymal transition can contribute to matrix remodeling. CSE has been shown to induce EMT in lung epithelial cells, but the signaling mechanisms involved are largely unknown and subject of this study. EMT was assessed in A549 and BEAS2B cells stimulated with CSE by qPCR, Western blotting and immunofluorescence for epithelial and mesenchymal markers, as were collagen production, cell adhesion and barrier integrity as functional endpoints. Involvement of TGF-β and HIF1α signaling pathways were investigated. In addition, mouse models were used to examine the effects of CS on hypoxia signaling and of hypoxia per se on mesenchymal expression. CSE induced EMT characteristics in A549 and BEAS2B cells, evidenced by decreased expression of epithelial markers and a concomitant increase in mesenchymal marker expression after CSE exposure. Furthermore cells that underwent EMT showed increased production of collagen, decreased adhesion and disrupted barrier integrity. The induction of EMT was found to be independent of TGF-β signaling. On the contrary, CS was able to induce hypoxic signaling in A549 and BEAS2B cells as well as in mice lung tissue. Importantly, HIF1α knock-down prevented induction of mesenchymal markers, increased collagen production and decreased adhesion after CSE exposure, data that are in line with the observed induction of mesenchymal marker expression by hypoxia in vitro and in vivo. Together these data provide evidence that both bronchial and alveolar epithelial cells undergo a functional phenotypic shift in response to CSE exposure which can contribute to increased collagen deposition in COPD lungs. Moreover, HIF1α signaling appears to play an important role in this process.
authors.affiliation: Department of Respiratory Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Irene M J
authors.initials: IM
authors.lastname: Eurlings
authors.affiliation: Department of Respiratory Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Niki L
authors.initials: NL
authors.lastname: Reynaert
authors.affiliation: Department of Radiation Oncology, GROW School for Oncology and Developmental Biology, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Twan
authors.initials: T
authors.lastname: van den Beucken
authors.affiliation: Department of Respiratory Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Harry R
authors.initials: HR
authors.lastname: Gosker
authors.affiliation: Department of Respiratory Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: C C
authors.initials: CC
authors.lastname: de Theije
authors.affiliation: Laboratory for Translational Research in Obstructive Pulmonary Diseases, Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium.
authors.forename: Fien M
authors.initials: FM
authors.lastname: Verhamme
authors.affiliation: Laboratory for Translational Research in Obstructive Pulmonary Diseases, Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium.
authors.forename: Ken R
authors.initials: KR
authors.lastname: Bracke
authors.affiliation: Department of Respiratory Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Emiel F M
authors.initials: EF
authors.lastname: Wouters
authors.affiliation: Department of Respiratory Medicine, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center, Maastricht, the Netherlands.
authors.forename: Mieke A
authors.initials: MA
authors.lastname: Dentener
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001980:Bronchi / Q000166:cytology; D015687:Cell Hypoxia / Q000187:drug effects; D002460:Cell Line; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects*; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects*; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D051379:Mice; D010641:Phenotype; D011650:Pulmonary Alveoli / Q000166:cytology; D015398:Signal Transduction / Q000187:drug effects; D012906:Smoke / Q000009:adverse effects*; D014026:Nicotiana / Q000737:chemistry*; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D015415:Biomarkers; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012906:Smoke; D016212:Transforming Growth Factor beta