Cellular crosstalk between airway epithelial and endothelial cells regulates barrier functions during exposure to double‐stranded RNA

• Published in: Immunity, Inflammation and Disease Vol. 5; no. 1; pp. 45 - 56
• Main Authors: Blume, Cornelia, Reale, Riccardo, Held, Marie, Loxham, Matthew, Millar, Timothy M., Collins, Jane E., Swindle, Emily J., Morgan, Hywel, Davies, Donna E.
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.03.2017; John Wiley and Sons Inc
• Subjects: Airway epithelial barrier; Asthma; Bronchi - cytology; Cell Communication; Cell culture; Cell Line; Cells, Cultured; cellular crosstalk; Chemokine CX3CL1 - metabolism; Chronic obstructive pulmonary disease; Coculture Techniques; Communication; Disease; Drugs; E-Selectin - metabolism; endothelial barrier; Epithelial Cells - physiology; Experiments; fractalkine (CX3CL1); Homeostasis; Human Umbilical Vein Endothelial Cells - physiology; Humans; Infections; Inflammation; Inflammatory diseases; Intercellular Adhesion Molecule-1 - metabolism; Metabolites; Microfluidics; Microscopy; Original Research; Penicillin; Poly I-C - pharmacology; RNA, Double-Stranded - pharmacology; tumor necrosis factor alpha; Tumor Necrosis Factor-alpha - metabolism; Umbilical cord; Viral infections; United Kingdom > UK; Airway epithelial barrier; endothelial barrier; fractalkine (CX3CL1); tumor necrosis factor alpha; cellular crosstalk
• ISSN: 2050-4527; 2050-4527
• DOI: 10.1002/iid3.139

Introduction The epithelial and endothelial barriers of the airway mucosa are critical for regulation of tissue homeostasis and protection against pathogens or other tissue damaging agents. In response to a viral infection, epithelial cells must signal to the endothelium to initiate immune cell recruitment. This is a highly temporal regulated process; however, the mechanisms of this cross‐talk are not fully understood. Methods In a close‐contact co‐culture model of human airway epithelial and endothelial cells, cellular crosstalk was analyzed using transepithelial electrical resistance (TER) measurements, immunofluorescence, electron microscopy, and ELISA. Viral infections were simulated by exposing airway epithelial cells apically to double‐stranded RNA (Poly(I:C)). Using a microfluidic culture system, the temporal release of mediators was analyzed in the co‐culture model. Results Within 4 h of challenge, double‐stranded RNA induced the release of TNF‐α by epithelial cells. This activated endothelial cells by triggering the release of the chemoattractant CX3CL1 (fractalkine) by 8 h post‐challenge and expression of adhesion molecules E‐selectin and ICAM‐1. These responses were significantly reduced by neutralising TNF‐α. Conclusion By facilitating kinetic profiling, the microfluidic co‐culture system has enabled identification of a key signaling mechanism between the epithelial and endothelial barriers. Better understanding of cell–cell cross‐talk and its regulatory mechanisms has the potential to identify new therapeutic strategies to control airway inflammation. Using a microfluidic in vitro co‐culture model we show that human airway epithelial cells activate the endothelial barrier by releasing TNF‐α resulting in CX3CL1 release and expression of adhesion molecules. By facilitating kinetic profiling, the microfluidic co‐culture system has enabled identification of temporal signaling events between the epithelial and endothelial barriers. Better understanding of cell–cell cross‐talk and its regulatory mechanisms has the potential to identify new therapeutic strategies to control airway inflammation.