Apical rigidity of an epithelial cell monolayer evaluated by magnetic twisting cytometry: ICAM-1 versus integrin linkages to F-actin structure

Abstract

Using Magnetic Twisting Cytometry (MTC) technique, we attempted to characterize in vitro the rigidity of the lining tissue covering the lung alveolar wall from its apical face. We purposely used a cellular model constituted by a monolayer of human alveolar epithelial cell (A549) over which microbeads, fixed to InterCellular Adhesion Molecule (ICAM-1), exert a controlled mechanical stress. ICAM-1 expression was induced by Tumor Necrosis Factor-α (TNF-α). Rigidity measurements, performed in the course of cytochalasin D depolymerization, reveal the force transmitter role of the transmembrane receptor ICAM-1 and demonstrate that ICAM-1 and F-actin linkages confers mechanical rigidity to the apical face of the epithelial cell monolayer resembling that provided by integrins. These results confirm the ability of MTC in identifying transmembrane mechanoreceptors in relation with F-actin. Molecular linkages between ICAM-1 and F-actin were observed by spatial visualisations of the structure after double staining of F-actin and anti ICAM-1 antibody through confocal microscopy.