title: Macrophages and dendritic cells express tight junction proteins and exchange particles in an in vitro model of the human airway wall.
abstract: The human airway epithelium serves as structural and functional barrier against inhaled particulate antigen. Previously, we demonstrated in an in vitro epithelial barrier model that monocyte derived dendritic cells (MDDC) and monocyte derived macrophages (MDM) take up particulate antigen by building a trans-epithelial interacting network. Although the epithelial tight junction (TJ) belt was penetrated by processes of MDDC and MDM, the integrity of the epithelium was not affected. These results brought up two main questions: (1) Do MDM and MDDC exchange particles? (2) Are those cells expressing TJ proteins, which are believed to interact with the TJ belt of the epithelium to preserve the epithelial integrity? The expression of TJ and adherens junction (AJ) mRNA and proteins in MDM and MDDC monocultures was determined by RT-PCR, and immunofluorescence, respectively. Particle uptake and exchange was quantified by flow cytometry and laser scanning microscopy in co-cultures of MDM and MDDC exposed to polystyrene particles (1 μm in diameter). MDM and MDDC constantly expressed TJ and AJ mRNA and proteins. Flow cytometry analysis of MDM and MDDC co-cultures showed increased particle uptake in MDDC while MDM lost particles over time. Quantitative analysis revealed significantly higher particle uptake by MDDC in co-cultures of epithelial cells with MDM and MDDC present, compared to co-cultures containing only epithelial cells and MDDC. We conclude from these findings that MDM and MDDC express TJ and AJ proteins which could help to preserve the epithelial integrity during particle uptake and exchange across the lung epithelium.
authors.affiliation: Department for Clinical Research, University of Bern, Bern, Switzerland.
authors.forename: Fabian
authors.initials: F
authors.lastname: Blank
authors.forename: Marc
authors.initials: M
authors.lastname: Wehrli
authors.forename: Andrea
authors.initials: A
authors.lastname: Lehmann
authors.forename: Oliver
authors.initials: O
authors.lastname: Baum
authors.forename: Peter
authors.initials: P
authors.lastname: Gehr
authors.forename: Christophe
authors.initials: C
authors.lastname: von Garnier
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Rothen-Rutishauser
mesh_terms: D022005:Adherens Junctions / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D056151:Airway Remodeling / Q000276:immunology; D000941:Antigens / Q000276:immunology; D002450:Cell Communication / Q000276:immunology; D018929:Cell Culture Techniques; D002454:Cell Differentiation / Q000276:immunology; D055252:Cell-Derived Microparticles / Q000276:immunology / Q000378:metabolism*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D004705:Endocytosis / Q000276:immunology; D004781:Environmental Exposure / Q000009:adverse effects; D006801:Humans; D008264:Macrophages / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D009000:Monocytes / Q000473:pathology; D052638:Particulate Matter / Q000009:adverse effects / Q000276:immunology; D020545:Respiratory Mucosa / Q000473:pathology*; D019108:Tight Junctions / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: D000941:Antigens; D052638:Particulate Matter