β2-Integrin Adhesive Bond Tension under Shear Stress Modulates Cytosolic Calcium Flux and Neutrophil Inflammatory Response

• Published in: Cells (Basel, Switzerland) Vol. 11; no. 18; p. 2822
• Main Authors: Morikis, Vasilios Aris, Chen, Szu Jung, Madigan, Julianna, Jo, Myung Hyun, Werba, Lisette Caroline, Ha, Taekjip, Simon, Scott Irwin
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 09.09.2022; MDPI
• Subjects: Affinity; Allosteric properties; Antibodies; Calcium influx; Calcium signalling; Conformation; Cooperation; Glass substrates; Immunological tolerance; Inflammation; Intercellular adhesion molecule 1; Leukocytes (neutrophilic); LFA-1 antigen; Mechanical stimuli; Neutrophils; Nucleotides; Proteins; Reactive oxygen species; Shear stress; T cell receptors; tension gauge tethers; β2-integrin; United States > US
• DOI: 10.3390/cells11182822
• ISSN: 2073-4409

On arrested neutrophils a focal adhesive cluster of ~200 high affinity (HA) β2-integrin bonds under tension is sufficient to trigger Ca2+ flux that signals an increase in activation in direct proportion to increments in shear stress. We reasoned that a threshold tension acting on individual β2-integrin bonds provides a mechanical means of transducing the magnitude of fluid drag force into signals that enhance the efficiency of neutrophil recruitment and effector function. Tension gauge tethers (TGT) are a duplex of DNA nucleotides that rupture at a precise shear force, which increases with the extent of nucleotide overlap, ranging from a tolerance of 54pN to 12pN. TGT annealed to a substrate captures neutrophils via allosteric antibodies that stabilize LFA-1 in a high- or low-affinity conformation. Neutrophils sheared on TGT substrates were recorded in real time to form HA β2-integrin bonds and flux cytosolic Ca2+, which elicited shape change and downstream production of reactive oxygen species. A threshold force of 33pN triggered consolidation of HA β2-integrin bonds and triggered membrane influx of Ca2+, whereas an optimum tension of 54pN efficiently transduced activation at a level equivalent to chemotactic stimulation on ICAM-1. We conclude that neutrophils sense the level of fluid drag transduced through individual β2-integrin bonds, providing an intrinsic means to modulate inflammatory response in the microcirculation.