Effect of neutrophil adhesion on the mechanical properties of lung microvascular endothelial cells.

Neutrophil adhesion to pulmonary microvascular endothelial cells (ECs) initiates intracellular signaling, resulting in remodeling of F-actin cytoskeletal structure of ECs. The present study determined the mechanical properties of ECs and the changes induced by neutrophil adhesion by atomic force microscopy. The elastic moduli of ECs were compared before neutrophils were present, as soon as neutrophil adhesion was detected, and 1 minute later. ECs that were adjacent to those with adherent neutrophils were also evaluated. Neutrophil adhesion induced a decrease in the elastic moduli in the 6.25-μm rim of ECs surrounding adherent neutrophils as soon as firmly adherent neutrophils were detected, which was transient and lasted less than 1 minute. Adjacent ECs developed an increase in stiffness that was significant in the central regions of these cells. Intercellular adhesion molecule-1 crosslinking did not induce significant changes in the elastic modulus of ECs in either region, suggesting that crosslinking intercellular adhesion molecule-1 is not sufficient to induce the observed changes. Our results demonstrate that neutrophil adhesion induces regional changes in the stiffness of ECs.