CD 18-mediated adhesion is required for the induction of a proinflammatory phenotype in lung epithelial cells by mononuclear cell-derived extracellular vesicles

Publication date: Available online 21 February 2018
Source:Experimental Cell Research
Author(s): Tommaso Neri, Valentina Scalise, Ilaria Passalacqua, Ilaria Giusti, Stefania Lombardi, Cristina Balia, Delfo D’Alessandro, Stefano Berrettini, Roberto Pedrinelli, Pierluigi Paggiaro, Vincenza Dolo, Alessandro Celi
Extracellular vesicles are submicron vesicles that upregulate the synthesis of proinflammatory mediators by lung epithelial cells.We investigated whether these structures adhere to lung epithelial cells, and whether adhesion is a prerequisite for their proinflammatory activity.Extracellular vesicles were generated by stimulation of normal human mononuclear cells with the calcium ionophore A23187, and labelled with carboxyfluorescein diacetate succinimidyl ester. Adhesion of vesicles to monolayers of immortalized bronchial epithelial (16HBE) and alveolar (A549) cells was analysed by fluorescence microscopy. The role of candidate adhesion receptors was evaluated with inhibitory monoclonal antibodies and soluble peptides. The synthesis of proinflammatory mediators was assessed by ELISA.Transmission electron microscopy confirmed the generation of closed vesicles with an approximate size range between 50 and 600nm. Adhesion of extracellular vesicles to epithelial cells was upregulated upon stimulation of the latter with tumour necrosis factor-α. Adhesion was blocked by an anti-CD18 antibody, by peptides containing the sequence RGD and, to a lesser extent, by an antibody to ICAM-1. The same molecules also blocked the upregulation of the synthesis of interleukin-8 and monocyte chemotactic protein-1 induced by extracellular vesicles.CD18-mediated adhesion of extracellular vesicles is a prerequisite for their proinflammatory activity.



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