title: Cigarette smoke-induced disruption of bronchial epithelial tight junctions is prevented by transforming growth factor-β.
abstract: The airway epithelium constitutes an essential immunological and cytoprotective barrier to inhaled insults, such as cigarette smoke, environmental particles, or viruses. Although bronchial epithelial integrity is crucial for airway homeostasis, defective epithelial barrier function contributes to chronic obstructive pulmonary disease (COPD). Tight junctions at the apical side of epithelial cell-cell contacts determine epithelial permeability. Cigarette smoke exposure, the major risk factor for COPD, is suggested to impair tight junction integrity; however, detailed mechanisms thereof remain elusive. We investigated whether cigarette smoke extract (CSE) and transforming growth factor (TGF)-β1 affected tight junction integrity. Exposure of human bronchial epithelial cells (16HBE14o(-)) and differentiated primary human bronchial epithelial cells (pHBECs) to CSE significantly disrupted tight junction integrity and barrier function. Specifically, CSE decreased transepithelial electrical resistance (TEER) and tight junction-associated protein levels. Zonula occludens (ZO)-1 and ZO-2 protein levels were significantly reduced and dislocated from the cell membrane, as observed by fractionation and immunofluorescence analysis. These findings were reproduced in isolated bronchi exposed to CSE ex vivo, as detected by real-time quantitative reverse-transcriptase PCR and immunohistochemistry. Combined treatment of 16HBE14o(-) cells or pHBECs with CSE and TGF-β1 restored ZO-1 and ZO-2 levels. TGF-β1 cotreatment restored membrane localization of ZO-1 and ZO-2 protein and prevented CSE-mediated TEER decrease. In conclusion, CSE led to the disruption of tight junctions of human bronchial epithelial cells, and TGF-β1 counteracted this CSE-induced effect. Thus, TGF-β1 may serve as a protective factor for bronchial epithelial cell homeostasis in diseases such as COPD.
authors.affiliation: Comprehensive Pneumology Center, Institute of Lung Biology and Disease, University Hospital, Ludwig-Maximilians-University and Helmholtz Zentrum München, Member of the German Center for Lung Research, Munich, Germany.
authors.forename: Andrea C
authors.initials: AC
authors.lastname: Schamberger
authors.forename: Nikica
authors.initials: N
authors.lastname: Mise
authors.forename: Jie
authors.initials: J
authors.lastname: Jia
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Genoyer
authors.forename: Ali Ö
authors.initials: AÖ
authors.lastname: Yildirim
authors.forename: Silke
authors.initials: S
authors.lastname: Meiners
authors.forename: Oliver
authors.initials: O
authors.lastname: Eickelberg
mesh_terms: D000818:Animals; D001980:Bronchi / Q000187:drug effects* / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005260:Female; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D020545:Respiratory Mucosa / Q000378:metabolism; D012906:Smoke / Q000009:adverse effects*; D012907:Smoking / Q000009:adverse effects; D019108:Tight Junctions / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000009:adverse effects*; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*; D015854:Up-Regulation; D062826:Zonula Occludens-1 Protein / Q000235:genetics / Q000378:metabolism; D062827:Zonula Occludens-2 Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D012906:Smoke; C569042:TJP1 protein, human; C569046:TJP2 protein, human; D053773:Transforming Growth Factor beta1; D062826:Zonula Occludens-1 Protein; D062827:Zonula Occludens-2 Protein